STEEL SHEET FOR CONTAINER AND METHOD OF MANUFACTURING THE
SAME
Technical Field -
[0001]
The present invention relates to a steel sheet for a container used as a material
in can-making, and in particular, exhibiting excellent can-making workability,
weldability, film adhesive properties, primary-paint adhesive properties,
secondary-paint adhesive properties, resistance to dorrosion under a coated film,
non-lacquering corrosion resistance, sulphide staining resistance, after-retort rust
resistance, and wettability.
The present application claims priority based on Japanese Patent Application
No. 2010-147860 filed in Japan on June 29, 2010, the disclosures of which are
incorporated herein by reference in their entirety.
Background Art
[0002]
Metal containers used for beverage or food can be broadly categorized into a
two-piece can and a three-piece can. For the two-piece can, which is typified by a DI
can, drawing and ironing are performed, then, lacquering is applied on the inner surface
side of the can, and lacquering and printing are applied on the outer surface side of the
can. For the three-piece can, lacquering is applied on a surface corresponding to the
inner surface of the can, printing is performed on a surface corresponding to the outer
surface of the can, and then, welding is app lied to a body portion of the can.
For both types of cans, the lacquering process is a necessary process performed
before or after the can-making. With regard to lacquering, a solvent-based lacquer or
water-based lacquer is used, and then, baking is performed. Through this lacquering
process, waste materials such as waste solvents resulting from these lacquers are
produced as industrial wastes, and exhaust gas (mainly carbon dioxide) is emitted to the
atmosphere. In recent years, effcrts for reducing these industrial'wastes and exhaust
gas have been undertaken with the aim of achieving global envirp9mental protection.
Among them, attention has been paid to a teclmique of laminating films as an
1/39.
alternative to the lacquers, and this technique is spreading rapidly.
[0003]
For the two-piece can, there have been provided a large number of inventions
concerning a method of manufacturing a can by laminating films, or other related
methods. These inventions include, for example:
Patent Document 1 "Method of Manufacturing a Drawn and Ironed Can";
Patent Document 2 "Drawn and honed C,an";
Patent Document 3 "Method of Manufacturing a Deep-drawn Thinned Can"; and
Patent Document 4 "Coated Steel Sheet for a Drawn and Ironed Can".
For the three-piece can, there have been proposed:
Patent Document 5 "Film-layered Steel Strip for Three-piece Can, and a Method of
Manufacturing the Same";
Patent Document 6 "Three-piece Can Having Multiple-layered Organic Film on the
Outer Surface of the Can";
Patent Document 7 "Steel Sheet for a Three-piece Can Having Striped Multiple-layered
Organic Film"; and
Patent Document 8 "Method of Manufacturing a Striped Laminate Steel Sheet for a
Three-piece Can".
[0004]
In many cases, a chromate film subjected to an electrolysis chromate treatment
is used for a steel sheet used as a base for the laminate film. The chromate film has a
two-layered structure including a hydrated Cr oxide layer provided on the upper layer of
a metal Cr layer.' This provides the laminate film (adhesive layer in the case where the
film has adhesive agent) with adhesiveness to the steel sheet by way of the hydrated Cr
oxide layer of the chromate film. It is said that this appearance of adhesiveness results
from a hydrogen bond between a hydroxy group of the hydrated Cr oxide and a function
group such as a carbonyl group and an ester group of the laminate film, although details
of a mechanism thereof are not clearly found.
[0005]
Further, a technique employing a Zr compound film in place of the
conventional chromate film includes: y
Patent Document 9 "Steel Sheet for a Container Exhibiting Excellent Can -making
2/39
Workability";
Patent Document 10 "Steel Sheet for a Container";
Patent Document 11 "Steel Sheet for a Container"; and
Patent Document 12 "Steel Sheet for a Container Exhibiting Excellent Organic Film
Property, and a Method of Manufacturing the Same".
Related Art Documents
Patent Documents
[0006]
Patent Document 1: Japanese Patent No. 1571783
Patent Document 2: Japanese Patent No: 1670957
Patent Document 3: Japanese Unexamined Patent Application, First Publication
''No. H02-263523
Patent Document 4: Japanese Patent No. 1601937
Patent Document 5: Japanese Unexamined Patent Application, First Publication
No. H03-236954
Patent Document 6 : Japanese Unexamined Patent Application, First
Publication No. H05-124648
Patent Document 7 : Japanese Unexamined Patent Application, First
Publication No. H05-111979
Patent Document 8 : Japanese Unexamined Patent Application, First
Publication No. H05-147181
Patent Document 9 : Jap
Publication No. 2007-284789
ese Unexamined Patent Application, First
c
Patent Document 10 : Japanese Unexamined Patent Application, First
Publication No. 2009-1852
Patent Document 11: Japanese Unexamined Patent Application, First
Publication No. 2009-1854
Patent Document 12 : Japanese Unexamined Patent Application, First
Publication No. 2010-13728
Disclosure of the Invention
3/39
Problems to be Solved by the Invention
[0007]
It is true that the above-described inventions are effective in achieving the
global environmental protection. However; in recent years, in the beverage container
industry, competition is fierce among a PET bottle, a glass bottle, paper, and other
materials in terms of cost and quality. Under such a circumstance, there is an
increasing demand for a conventional lacquer applied to the above-described laminate
steel sheet for a container and capable of providing excellent film adhesive properties,
primary-paint adhesive properties, secondary-paint' adhesive properties, resistance to
corrosion under a coated film, and non-lacquering corrosion resistance, and providing
further improved can-making workability, film adhesive properties, in particular, film
adhesive properties after working, resistance to corrosion under a coated film, and
non-lacquering corrosion resistance.
[0008]
In particular, for a Zr film, which is a new film and is alternative to the
chromate film, Ni plating or Sn plating is applied, and then, a rinsing treatment for
cleaning a plating solution is applied in a conventional manufacturing method, which
results in formation of hydroxide of Ni or Sn on an Ni- or Sn-plated layer.' Thus, even
if the Zr film is formed thereafter, the formed hydroxide film inhibits bonding of the Zr
film with the plating metal, which makes it impossible to achieve sufficient
performances. Further, this phenomenon employs an increase in pH caused by a
hydrogen ion consumption during cathode electrolysis to change a Zr ion into Zr
hydrate, thereby forming the Zr film. Thus, this method does not have any effect of
cleaning the surface of the plated material, which is an inevitable principle problem.
[0009]
In view of the circumstances described above, the present invention has been
made and an object of the present invention is to provide a steel sheet for a container
formed mainly by a Zr film, which exhibits excellent can-making workability,
weldability, film adhesive properties, primary-paint adhesive properties,
secondary-paint adhesive properties, resistance to corrosion under a coated film,
non-lacquering corrosion resistance, sulphide staining resistance,. after-retort rust
resistance, and wettability.
4/39.
Means for Solving the Problems
[0010]
The present invention has been made to solve the above-described problem,
and has the following modes.
(1) A first mode of the present invention provides a steel sheet for a container,
including a cold-roiled steel sheet; and a composite film formed on the cold-rolled steep
sheet through an electrolysis process in a solution containing: at least one metal ion of
an Sn ion, an Fe ion, and an Ni ion; a Zr ion; a nitric acid ion; and an ammonium ion, in
which the composite film contains at least one element of: Zr of 0.1 to 100 mg/m2 in
equivalent units of metal Zr: Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn; Fe of
5 to 2000 mg/m2 in equivalent units of metal Fe; and Ni of 5 to 2000 mg/m2 in
'equivalent units of metal Ni.
a
(2) According to the steel sheet for a container described in (1) above, the solution
may further contain at least one of a phosphoric acid ion and a phenolic resin, and the
composite film may further contain at least one of a phosphoric acid compound of 0.1 to
50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50 mg/m2 in equivalent
units of C.
(3) According to the steel sheet for a container described in (2) above, the solution
may further contain a fluorine ion, and the composite film may further contain a
fluorine compound of not more than 0.1 mg/m2 in equivalent units of F.
(4) According to the steel sheet for a container described in any one of (1) to (3)
above, the cold-rolled steel sheet may have, at least one side surface including at least
one of an Sn-plated layer containing Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn,
a
and an Ni-plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
^5) According to the steel sheet for a container described in (4) above, the at least
one side surface of the cold-rolled steel sheet may have the Sn-plated layer, and at least
part of the Sn-plated layer may be alloyed with the cold-rolled steel sheet through a
tin-reflow treatment.
(6) According to the steel sheet for a container described in (4) above, the at least
one side surface of the cold-rolled steel sheet may have the Sn-plated layer, and there
a
may be provided, below the Sn-plated layer, a Ni-plated layer, an Fe-Ni alloy plated
5/39
layer, or a Ni-diffusion plated layer obtained through a thermal treatment after Ni
plating.
(7) According to the steel sheet for a container described in (6) above, the at least
one side surface of the cold-rolled steel sheet may have the Sn-plated layer, and all or
part of the Sn-plated layer may be alloyed with the cold-rolled steel sheet through a
tin-reflow treatment.
(8) A second mode of the present inyention provides a method of manufacturing a
steel sheet for a container, including: applying an electrolysis process to a cold-rolled
steel sheet in a solution containing: at least one metal ion of an Sn ion, an Fe ion, and an
Ni ion; a Zr ion; a nitric acid ion, and an ammonium ion, to precipitate on the
cold-rolled steel sheet, and forming a composite film containing at least one element of:
Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr; Sn of 0.3 to 20 g/mz in
equivalent units of metal Sn; Fe of 5 to 2000 mg/ nz in equivalent units of metal Fe; and
s
Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
(9) According to the method of manufacturing a steel sheet described in (8) above,
the cold-rolled steel sheet may have at least one side surface including at least one of an
Sn-plated layer containing Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn, and an
Ni-plated layer containing Ni of 5 to 2000 mg/mz in equivalent units of metal Ni.
(10) According to the method of manufacturing a steel sheet described in (8) above,
the solution may further contain at least one of a phosphoric acid ion and a phenolic
resin, and the composite film may further contain at least one of a phosphoric acid
compound of 0.1 to 50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50
mg/m2 in equivalent units of C.
(11) According to the method of manufacturing a steel sheet described in any one of
e
(8) to (10) above, it may be possible to applya cleaning process of an immersion
process or spray process with hot water at not less than 40°C for not less than 0.5
second after the composite film is formed on the cold-rolled steel sheet.
Effects of the Invention
[0011]
According to the present invention; it is possible to obtain a steel sheet for a
container having excellent properties suitable for a can, and exhibiting excellent
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can-making workability, weldability, film adhesive properties, primary-paint adhesive
properties, secondary-paint adhesive properties, resistance to corrosion under a coated
film, non-lacquering corrosion resistance, sulphide staining resistance, after-retort rust
resistance, and wettability.
Brief Description of the Drawings
[0012]
FIG. I is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet I.
FIG. 2 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 2.
FIG. 3 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 3.
FIG. 4 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 4.
FIG. 5 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 5.
FIG. 6 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 6:=
FIG. 7 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 7.
FIG. 8 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 8.
FIG. 9 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 9.
Embodiments of the Invention
[0013]
The present inventors made a keen study of how to make full use of a Zr film,
which is a new film alternative to a chromate film. As a result, the present inventors
found that by applying an electrolysis process with a treatment solution containing, for
example, an Sn ion or an Ni ion to form a Zr film or a Zr film having a phosphoric acid
7/39
film or phenolic resin film combined with the Zr film, it is possible to simultaneously
precipitate the Zr film and the film of Sn or Ni, thereby significantly improving
properties for a can such as a film adhesive properties and resistance to corrosion under
a coated film. It is considered that this is because the bonding with the surface of a
material to be treated is strengthened, by precipitating, along with the Zr film, a metal
existing in the surface of a plating layer formed by Ni or Sn.
The present inventors also found that, with the presence of a Cr ion in a
treatment solution, a chromate film is formed before the simultaneous precipitation of
the Zr film and Sn or Ni through the electrolysis process, inhibiting the formation of the
Zr film. Thus, it is necessary to remove the Cr ion in the treatment solution.
[0014]
Hereinbelow, a steel sheet for a can according to an embodiment of the present
invention based on the above-described findings will be described.
[0015]
The steel sheet for a container according to this embodiment provides a steel
sheet for a can obtained by plating a cold-rolled steel sheet or a steel sheet with at least
one metal of Sn, Fe and Ni (hereinafter, collectively referred to as "base sheet'), and
subjecting the base sheet to an electrolysis process in a solution containing: at least one
metal ion of an Sn ion, an Fe ion, and an Ni ion; a Zr ion; a nitric acid ion; and an
ammonium ion, thereby forming a composite film containing the above-described
metallic element on the base sheet. The composite film contains:
(1) Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr, and
(2) at least one element of Sn of 0.3 to 20g/mz in equivalent units of metal Sn, Fe of 5 to
2000 mg/m2 in equivalent units of metal Fe, and Ni of 5 to 2000 mg/m2 in equivalent
units of metal Ni.
[0016]
The steel sheet for a container according to this embodiment has, on the base
sheet, a composite film containing (I) predetermined amount of Zr and (2)
predetermined amount of at least one element of Sn, Fe, and Ni. More specifically, as
described later, each of the elements constituting the composite film contributes to
improving at least one properties of the can-making workability, the weldability, the
film adhesive properties, the primary-paint adhesive properties, the secondary-paint
8/39
adhesive properties,=the resistance to corrosion under a coated film, the non-lacquering
corrosion resistance, the sulphide staining resistance, the after-retort rust resistance, and
the wettability.
It should be noted that it is only necessary that the "composite film" contains
the above-described metallic elements, and fonnation thereof is not limited. In other
words, each of the metallic elements may be contained as a single-element metal, or
may be contained as alloys of the metallic elements, or as a compound such as oxide,
hydroxide, halide, and phosphoric acid compounds partially containing the metallic
element.
Further, the composition of the composite film may not be uniform. The
composite film may have a layered structure in which each constituent element or part
of the constituent elements is separated, or constituent elements may form a gradation in
a film-thickness direction.
[0017]
According to the present invention, there is not any particular limitation to the
base sheet. It may be possible to use a steel sheet normally used as a material for a
container. Further, there is not any particular limitation to a material or a method for
manufacturing the base sheet. The base sheet is manufactured through normal
processes used for manufacturing the steel sheet, and then applying hot rolling, pickling,
cold rolling, annealing; temper rolling, or other processes. In the case where a
surface-treated layer containing one or more elements of Ni and Sn is added to the base
sheet, there is not any particular limitation to the addition method For example, it
may be possible to use a publicly known technique such as electroplating, vacuum
deposition and sputtering, or use a combination of heating treatments for adding a
diffusion layer. Further, the nature of the present invention remains unchanged if
Fe-Ni alloy plating is applied for Ni.
In order to form a high-quality composition layer, it is preferable that the base
sheet is a steel sheet obtained by, before Sn plating, applying an Ni-plated layer, an
Fe-Ni alloy plated layer, and an Ni-diffusion plated layer through a thermal treatment
applied after the Ni plating, and it is more preferable that the base sheet is obtained by,
after the Sn plating, alloying all or part of the Sn plating with a base metal through a
tin-reflow treatment.
9/39
[0018]
According to the steel sheet for a container according to this embodiment, a
composite film is formed on the upper layer of the above-described steel sheet (base
sheet). The thickness of the base sheet (base steel sheet) is determined depending on
applications.
Next, roles of the metals constituting the composite film will be described.
[0019]
Zr is an essential component for the composite film of the steel sheet for a
container according to this embodiment.
In the composite film, Zr contributes to obtaining the film adhesive properties,
the primary-paint adhesive properties, the secondary-paint adhesive properties, the
resistance to corrosion under a coated film, and the non-lacquering corrosion resistance.
Additionally, Zr also contributes to preventing sulfuration and blackening with which a
sulfur compound existing in contents reacts with the base steel, Sn and Ni to form black
sulfides. Zr forms Zr oxide, Zr hydroxide, Zr fluoride, Zr phosphate or other Zr
compound, or composites thereof. These Zr compounds exhibit excellent film
adhesive properties, primary-paint adhesive properties, secondary-paint adhesive
properties, resistance to corrosion under a coated film, non-lacquering corrosion
resistance, and sulphide staining resistance.
When Zr in the composite film reaches 0.1 mg/m2 or more in terms of metal Zr
amount, the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, the resistance to corrosion under a coated film, and
the non-lacquering corrosion resistance start to improve. However, in practice, it is
preferable to set Zr to 1 mg/m2 or more in equivalent units of metal Zr to obtain the
stable and adequate corrosion resistance and the adhesiveness.
Further, with the increase in the amount of Z in the composite film, the effect
of improving the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, the resistance to corrosion under a coated film, and
the non-lacquering corrosion resistance increases. However, in the case where the
amount of Zr exceeds 100 mg/m2 in equivalent units of metal Zr, the film adhesive
properties, the primary-paint adhesive properties, and the secondary-paint adhesive
properties of the composite film itself deteriorate, and the electric resistance increases,
10/39
deteriorating weldability. Further, the excellent non-lacquering corrosion resistance
resulting from the sacrificial protection by metal Sn is impaired, and uniform solubility
of So in the contents containing organic acid is inhibited. For these reasons, it is
necessary to set the amount of attached Zr film to be in the range of 0.1 to 100 mg/m2 in
terms of metal Zr amount.
[0020]
As described above, the composite film contains at least one element of Sn, Fe,
and Ni. Next, preferable amount of each of the elements contained will be described.
[0021]
[Sn: 0.3 to 20 g/m2 in equivalent units of metal Sn]
So is normally contained in the composite film in a form of a metal or alloy.
However, Sn may be contained in a form of a compound such as an oxide. Sn
provides excellent can-making workability, resistance to corrosion under a coated film,
non-lacquering corrosion resistance, and weldability. To achieve these effects, it is
necessary for the composite film to contain Sn of 0.3 g/m2 or more in the form of metal
Sn. It is desirable for the composite film to contain Sn of 0.5 g/m2 or more in
equivalent units of metal Sn to obtain rapid and sufficient weldability, and Sn of 2 g/m2
or more in equivalent units of metal Sn to obtain sufficient non-lacquering corrosion
resistance. With the increase in the amount of Sn attached, the effects obtained from
Sn of providing improved can-making workability, resistance to corrosion under a
coated film, non-lacquering corrosion resistance, and weldability increase. However,
in the case where the amount of Sn exceeds 20 g/m2, the effect of Sn saturates, and the
excessive amount of Sn leads to an economic disadvantage. Thus, the amount of Sn
attached may be set to 20 g/m2 or less in equivalent units of metal Sn. Further, by
applying So reflow treatment (tin-reflow treatment) after the Sn plating, an Sn alloy
layer is formed, thereby further improving the corrosion resistance.
[0022]
[Fe: 5 to 2000 mg/m2 in equivalent units of metal Fe]
Fe is normally contained in the composite film in a form of a metal or alloy.
However, Fe may be contained in a form of a compound such as an oxide. Fe provides
excellent weldability. To obtain this effect, it is necessary for the composite film to
contain Fe of 5 mg/m2 or more in equivalent units of metal Fe. With the increase in
11/39
the amount of Fe attached, the effect of improving the weldability increases. However,
in the case where the amount of Fe exceeds 2000 mg/m2, the effect of improving the
weldability saturates, and the excessive amount of Fe leads to an economic
disadvantage. Thus, the amount of Fe attached is set to be not less than 5 mg/m2 and
not more than 2000 mg/m2 in equivalent units of metal Fe.
[0023]
[Ni: 5 to 2000 mg/m2 in equivalent units of metal Ni]
Ni is normally contained in the composite film in a form of a metal or alloy.
However, Ni may be contained in a form of a compound such as an oxide. Ni has an
effect on the primary-paint adhesive properties, the secondary-paint adhesive properties,
the film adhesive properties, the resistance to corrosion under a coated film, and the
weldability. To achieve these effects, it is necessary for the composite film to contain
Ni of 5 mg/m2 or more in equivalent units of metal Ni. To obtain rapid and sufficient
weldability and sufficient resistance to corrosion under a coated film, it is desirable to
add Ni of 150 mg/m2 or more. With the increase in the amount of Ni attached, the
excellent effect obtained from Ni of improving the film adhesive properties, the
resistance to corrosion under a coated film, and the weldability increases. However, in
the case where the amount of Ni exceeds 2000 mg/m2 or more, the effect of improving
these properties saturates, and the excessive amount of Ni leads to an economic
disadvantage. Thus, the amount of Ni attached is set to be not less than 5 mg/m2 and
not more than 2000 mg/m2 in equivalent units of metal Ni.
[0024]
It should be noted that, in the case where the composite film contains Cr, an
improvement in the resistance to corrosion under a coated film can be expected.
However, as described above, with the existence of a Cr ion in the treatment solution,
before the Zr film and Sn, Ni, or other element are simultaneously precipitated, a
chromate film is formed through the electrolysis process, whereby the formation of the
Zr film is inhibited. This leads to a deterioration in performances such as weldability.
Thus, according to the present invention, it is preferable that the composite film does
not contain Cr.
[0025]
As a method for adding the composite film described above on the base sheet,
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there is a method of'applying a cathodic electrolysis process (hereinafter, also simply
referred to as "electrolysis process") in a solution containing: at least one metal ion of
an Sn ion, an Fe ion, and an Ni ion; a Zr ion; a nitric acid ion; and an ammonium ion.
It is preferable that, in particular, the electrolysis process is performed under conditions
in which these elements are precipitated simultaneously.
It should be noted that there is a method of simply immersing the steel sheet in
the solution described above to form the film. However, with this immersion method,
the base is subjected to etching to form the fiZr film, and attachment does not uniformly
occur, which makes it difficult to form the composite film of the steel sheet for a
container according to this embodiment.
With the cathodic electrolysis process, electric charges are forcibly moved, pH
increases due to hydrogen ion consumption at an interface of the steel sheet. Further,
the Zr film has an attachment-facilitating effect. These make it possible to obtain an
uniform film through a process applied within a short period of time ranging from
several seconds to several tens of seconds, which provides significant industrial
advantage. Further, a nitric acid ion is reduced through the cathode electrolysis, a
hydroxide ion is discharged, whereby pH of the interface of the steel sheet is more
likely to increase. When insoluble anode is used, an ammonium ion is reduced to be a
nitrous acid ion or nitric acid ion to supply the nitric acid ion consumed at the cathode,
and pH is made stable, which are also advantages of the cathodic electrolysis process.
[0026]
It should be noted that, according to the steel sheet for a container according to
this embodiment, it is preferable that the composite film is formed by:
(1) a Zr film layer formed mainly by Zr, and
(2) a film layer formed mainly by at least one element of Sri, Fe, and Ni, and,
the surface of the composite film is formed by the (1) Zr film layer formed mainly by
Zr.
More specifically, it is preferable that, by applying an electrolysis process to a
base sheet in a solution containing: at least one metal ion of Sri ion, Fe ion, and Ni ion;
Zr ion; nitric acid ion; and ammonium ion to form a composite film containing
compounds of the metals described above on the base sheet, the steel sheet for a
container has the composite film configured such that a film layer formed mainly by at
13/39
least one element of Sn, Fe, and Ni is formed on a base sheet, and above the film layer,
a Zr film layer formed mainly by Zr is formed, in other words, the composite film has a
gradation of metal elements constituting the film.
[0027]
Further, in the steel sheet for a container according to the present invention,
from the viewpoint of enhancing the film adhesive properties between the composite
film and the base sheet after working, it is preferable that the composite film contains:
(1) Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr,
(2) Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn, Fe of 5 to 2000 mg/m2 in terms
of metal Fe amount, and Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni, and
(3) at least one of a phosphoric acid compound of 0.1 to 50 mg/m2 in equivalent units of
P and a phenolic resin of 0.1 to 50 mg/m2 in equivalent units of C.
The composite film containing (3) at least one of the phosphoric acid and the
phenolic resin can be obtained by applying an electrolysis process to a steel sheet in a
solution in which at least one of fluorine ion, phosphoric acid ion, and phenolic resin is
further added to the above-described solution.
It should be noted that the composite film containing (3) at least one of the
phosphoric acid and the phenolic resin can be formed by applying the electrolysis
process in a similar manner as described above.
[0028]
The fluorine ion forms a complex, and contributes to stabilization of the Zr ion.
Thus, by adding the fluorine ion for the purpose of stabilizing Zr in an electrolyte
solution (forming chelate and diffusing), the allowable range of pH, concentration and
temperature increases, which makes operations easy.
However, when absorbed in the composite film, F causes a deterioration in the
adhesiveness (secondary adhesive properties) or after-retort rust resistance in a
high-temperature sterilization process such as a retort process, or resistance to corrosion
under a coated film, although not having any effect on the normal adhesiveness
(primary adhesive properties) of paint or film. It is considered that this is because the
fluorine ion in the film elutes to steam or etching solution, decomposes the bonding
with the organic film or corrodes the base steel sheet. Thus, in the case where the
amount of fluorine compound contained in the composite film exceeds 0.1 mg/m2 in
14/39
equivalent units of F, the deterioration in these properties becomes apparent. For these
reasons, the amount of fluorine compound contained in the composite film is set
preferably to 0.1 mg/m2 or less in equivalent units of F.
[0029]
It should be noted that, in the case where the fluorine remains in the composite
film as described above, the film adhesive properties, the secondary-paint adhesive
properties and other properties deteriorate. Thus, when used, the fluorine needs to be
removed as much as possible with hot-water cleaning. The fluorine needs to be
removed as much as possible with hot-water cleaning immediately after the composite
film is formed. The purpose of cleaning with the hot water is to clean the treatment
solution and improve the wettability. In particular, cleaning with the hot water
improves the wettability, and hence, suppresses occurrence of pinholes caused by
repellence of lacquer. This significantly improves the lacquering properties,
contributing to securing quality of the lacquered steel sheet. In order to sufficiently
obtain the wettability, the surface tension of 31 mN/m or more is necessary, and the
surface tension of 35 mN/m or more is preferable. The surface tension in this
specification is a value measured with a method specified in JIS K 6768. Under this
standard, test solutions having various surface tensions are applied, and measurement is
performed in a wet condition with the test solutions. Thus, if the wet condition with
the test solution having high surface tension is favorable, the composite film has
excellent wettability. Thus, the wettability can be evaluated in association with the
surface tension of the test solution.
[0030]
Although details of how this hot-water cleaning improves the wettability are
not known, it is considered that this is because hydrophilic functional groups increase in
the outermost layer of the film. To achieve these effects, it is necessary to apply a
cleaning process including an immersion process or spray process with hot water at
40°C or more for 0.5 sec or more. From the industrial viewpoint, it is preferable to
apply the spray process from which the cleaning-facilitating effect resulting from
flowing of liquid is expected, or a combination of the spray process and the immersion
process.
[0031]
15 / 39
Further, the effect of the hot-water cleaning includes removal of the fluorine
ion entering the composite film in the case where the solution contains the fluorine ion.
As described above, fluorine entering the composite film may deteriorate the film
adhesive properties, the secondary-paint adhesive properties and the after-retort rust
resistance, or the resistance to corrosion under a coated film of the composite film. To
set the amount of fluorine compound contained to be not more than 0.1 mg/m2 in
equivalent units of F to avoid such a deterioration, it is only necessary to apply the
cleaning process including the immersion process and/or spray process using the hot
water after the formation of the composite film. Further, by setting the process
temperature higher or setting the process duration longer, it is possible to reduce the
amount of F. Thus, to set the amount of fluorine compound contained in the film to be
not more than 0.1 mg/m2 in equivalent units of F, it is only necessary to apply the
immersion process or spray process with hot water at 40°C or more for 0.5 sec or more.
In the case where the water temperature is less than 40°C or the process duration is less
than 0.5 sec, the amount of fluorine compound contained in the composite film cannot
be reduced to be 0.1 mg/m2 or less in equivalent units of F, so that the properties
described above cannot be achieved.
[0032]
The purpose of adding the phosphoric acid compound to the composite film is
to obtain the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, and in particular, the film adhesive properties after
working. The phosphoric acid. compound includes Fe phosphate which is formed
through reaction with the base sheet, Sn phosphate, Ni phosphate and Zr phosphate, a
film such as the phosphate-phenolic resin film, and a composite thereof These
phosphoric acid compounds have excellent resistance to corrosion under a coated film,
film adhesive properties, primary-paint adhesive properties, and secondary-paint
adhesive properties. Thus, with the increase in the phosphoric acid compound, the
resistance to corrosion under a coated film, the film adhesive properties, primary-paint
adhesive properties, and the secondary-paint adhesive properties increase. Then, if the
phosphoric acid compound in the composite film reaches 0.1 mg/in2 or more in
equivalent units of P, it is possible to obtain the practically adequate level of the
resistance to corrosion under a coated film, the film adhesive properties, the
16/39
primary-paint adhesive properties, and the secondary-paint adhesive properties.
Further, with the increase in the amount of phosphoric acid compound, the effect of
improving the resistance to corrosion under a coated film, the film adhesive properties,
the primary-paint adhesive properties, and the secondary-paint adhesive properties also
further increases. However, in the case where the amount of phosphoric acid
compound exceeds 50 mg/m2 in equivalent units of P, the amount of phosphoric acid
compound is undesirably high, deteriorating the film adhesive properties, the
primary-paint adhesive properties, and the secondary-paint adhesive properties of the
composite film. Further, the electrical resistance increases, deteriorating the
weldability. For these reasons, it is preferable to set the amount of phosphate in the
range of 0.1 to 50 mg/m2 in equivalent units of P.
[0033]
In the composite film, the phenolic resin film contributes to obtaining the film
adhesive properties, the primary-paint adhesive properties, the secondary-paint adhesive
properties, and in particular, the film adhesive properties after working. Since the
phenolic resin is an organic substance, the phenolic resin itself has extremely excellent
adhesiveness to the paint and the laminate film. In the case where the surface-treated
layer is subjected to working such that the surface-treated layer largely deforms,
cohesive failure occurs in the surface-treated layer itself due to the working, possibly
deteriorating the adhesiveness. However, the phenolic resin has an effect of
significantly improving the adhesiveness after the working of the composite film.
Thus, with the increase in the phenolic resin, the film adhesiveness, the primary-paint
adhesive properties, and the secondary-paint adhesive properties further improve. In
the case where the amount of phenolic resin in the composite film reaches 0.1 mg/m2 or
more in equivalent units of C, it is possible to secure the practically adequate level of
adhesiveness. Further, with the increase in the amount of phenolic resin, the effect of
improving the film adhesiveness, the primary-paint adhesive properties and the
secondary-paint adhesive properties further increases. However, in the case where the
amount of phenolic resin in the composite film exceeds 50 mg/m2 in equivalent units of
C, the electrical resistance increases, deteriorating the weldability. Thus, it is
preferable to set the amount of phenolic resin to be in the range of 0.1 to 50 mg/m2 in
equivalent units of C.
17/39
[0034]
The phenolic resin used in the steel sheet for a container according to this
embodiment includes, for example, a polymer expressed by following Formula (1).
This can be manufactured by forming condensation polymer of phenolic compound,
naphthol compound or bisphenols (bisphenol A or F), and formaldehyde, and then
introducing functional groups X1 and X2 using formaldehyde and amine. Formalin is
generally used as the formaldehyde . Although the molecular weight of the polymer is
not particularly limited, the molecular weight is set generally in the range of
approximately 1000 to 1000000, preferably in the range of approximately 1000 to
100000, more preferably in the range of approximately 1000 to 10000. The molecular
weight can be measured with a gel permeation chromatography after the film is
detached.
[Formula 1]
(1)
In Formula (1), XI independently represents a hydrogen atom or Z' group
expressed by following Formula (II) in each structural unit, YI represents a hydrogen
atom, a hydroxy group, an alkyl group with CI to C5, a hydroxy alkyl group with CI to
C5, an aryl group with C6 to C12, a benzyl group, or a group expressed by following
Formula (III), and Y2 represents a hydrogen atom. Further, in the case where Y2 exists
adjacent to Y', Y' and Y2 may integrally form a condensed benzene ring including a
bonding between Y' and Y2. In this specification, the ratio of Z' group + Z2 group
introduced is 0.2 to 1.0 piece per benzene ring.
[0035]
[Formula 2]
V=-CIL -NI-r W
In Formula (II), R' and R2 independently represent a hydrogen atom, an alkyl
group with Cl to CIO or hydroxy alkyl group with CI to CIO.
18/39
[0036]
[Formula 3]
R'
I
- c -< O >--on
In Formula (III), R3 and R4 independently represent a hydrogen atom, an alkyl
group with CI to CIO, or hydroxy alkyl group with C1 to C1O. In the case where YI is a
group expressed by Formula (II1) described above, X2 represents a hydrogen atom or Z2
group expressed by General Formula (IV) in each structural unit expressed by Formula
M.
[0037]
[Formula 4]
R`
V CIL, -
Rw
(IV)
In Formula (IV), R5 and R6 independently represent a hydrogen atom, an alkyl
group with CI to CIO, or a hydroxy alkyl group with CI to C10.
[0038]
It should be noted that, for the steel sheet for a container according to this
embodiment, it maybe possible to measure the amount of Sn, the amount of Ni, the
amount of Fe, the amount of Zr, the amount of P, and the amount of F contained in the
composite film, for example, through a quantitative analysis method such as fluorescent
X-ray analysis. Further, in the case where a metal same as that forming the steel sheet
to be treated (base sheet) is attached, it is only necessary to apply the treatment to a
different metal sheet such as a copper sheet, and perform the measurement. Further,
the amount of C contained in the phenolic resin film can be measured by subtracting the
amount of C existing in the steel sheet using a total organic carbon analyzer (TOC).
[0039]
Depending on manufacturing facility or manufacturing speed (ability),
concentrations of ions in the treatment solution used in the cathodic electrolysis process
for forming the composite film may be adjusted so as to be:
concentration of Sn ion, Fe ion, and Ni ion: approximately 10 to 30000 ppm;
concentration of Zr ion: approximately 100 to 20000 ppm;
19 / 39
concentration of ammonium ion: approximately 100 to 20000 ppm;
concentration of nitric acid ion: approximately 100 to 20000 ppm;
concentration of phosphoric acid ion: approximately 100 to 50000 ppm;
concentration of phenolic resin: approximately 50 to 2000 ppm; and
concentration of fluorine ion: approximately 500 to 30000 ppm.
Examples
[0040]
Next, using Examples, the present invention will be described more in detail.
However, the present invention is not limited to these Examples, and various
modifications are possible within the scope of the present invention.
[0041]
[Manufacture of base sheet]
Table I shows methods of manufacturing base sheets 1 to 9 having a thickness
in the range of 0.15 to 0.25 mm used in Examples t to 19 and Comparative Examples I
to 8. FIG. 1 to FIG. 9 are diagrams illustrating configurations of steel sheets S for a
container used for the base sheets 1 to 9. In the drawings, numbers 1 to 9 represent a
base sheet number, A represents a cold-rolled steel sheet, B represents plating, C
represents a composite film, and S represents a steel sheet for a container. Note that, in
the drawings, at least part of an Sn-plated layer may be alloyed with a cold-rolled steel
sheet through a tin-reflow treatment.
[0042]
Further, Table 2A and Table 2B show base sheets used for Examples I to 19
and Comparative Examples 1 to 8. Note that, in Examples 9, 11 to 15, 23 to 25, 27
and 28, and Comparative Example 1 and Comparative Example 6, after the Sri plating,
electric heating was applied to melt Sri, and then a cooling treatment was applied by
immersing the sheets in hot water at 80°C.
[0043]
[Formation of composite film]
Next, a composite film was added to the surface of each of the base sheets
under conditions for treatment of composite films shown in Table 3A and Table 3B.
More specifically, in a state where the base sheets were immersed in the treatment
20/39
solution having an appropriate amount of chemical agents described below, a cathodic
electrolysis process was performed on the basis of the electrolysis process duration and
electric current density shown in Table 3A and Table 3B, thereby forming the composite
film.
The chemical agents used include commercially available Zr nitrate, Zr
ammonium fluoride, hydrofluoric acid, ammonia nitrate, Sn nitrate, Fe nitrate, Ni nitrate,
and phosphoric acid.
Further, as for a low-molecular phenolic resin, a low-molecular phenolic resin
having an average molecular weight of 3000, which is a polymer having ZI =
-CH2N(CH3)2 for X', Y' = Y2 = hydrogen atom, and a ratio of Z' group introduced of
0.5 piece per benzene ring in the general Formula (I) described above, was used in a
form of water-soluble polymer having a solid content of 2.0 g/L and pH of 6.0 (adjusted
with phosphoric acid).
[0044]
[Rinsing treatment]
After the composite film was formed through the above-described processes, a
rinsing treatment was applied through the following treatment method (a) or (b) to
control the amount of F in the composite film.
(a) Immersing the composite film in hot water at 40°C or more.
(b) Immersing the composite film in water at ordinary temperature of
approximately 15°C.
[0045]
[Performance evaluation]
For test materials having the above-described treatments applied thereto, the
amount of Zr, P, C, F, Sn, Fe, and Ni attached to the composite film was measured.
The results of the measurement are shown in Table 4A and Table 4B. Further,
performance evaluation on the following items (A) to (J) was performed. The results
of the evaluation are shown in Table 5A and Table 5B.
[0046]
(A) Can-making workability
A PET film having a thickness of 20 μm was laminated on both sides of the test
material at 200°C; can-making working was performed sequentially through drawing
21 / 39
and ironing; and formed items were evaluated in four grades (A: Excellent, B: Good, C:
Defect occurred, and D: Broken and unable to continue working).
[0047]
(B) Weldability
Under conditions of welding wire speed of 80 m/min, the test materials were
welded with a wire seam welder while electric current were varied. Then, weldability
was systematically evaluated in four grades (A: Excellent, B: Good, C: poor, and D:
Unable to weld) based on the appropriate electrical-current range including the
minimum electrical-current value at which the sufficient welding strength can be
obtained, and the maximum electrical-current value at which welding defects such as
spatter and welding spatter start to become conspicuous.
[0048]
(C) Film adhesive properties
A PET film having a thickness of 20 pm was laminated on both sides of the test
material at 200°C; the test material was subjected to drawing-ironing to form a can
body; the can body was subjected to a retort process at 125°C for 30 minutes; and the
film detachment state was evaluated in four grades (A: No detachment was found, B:
Minor detachment occurred but practically ignorable, C: Minor detachment occurred,
and D: Most part was detached).
[0049]
(D) Primary-paint adhesive properties
An epoxy-phenolic resin was applied to the test material; the rein was baked at
200°C for 30 minutes; then, cross-cut having a depth that reaches a base iron was
applied at 1 mm intervals; the resin was detached with a tape; and, a detached state was
evaluated in four grades (A: No detachment was found, B: Minor detachment occurred
but practically ignorable, C: Minor detachment occurred, and D: Most part was
detached).
[0050]
(E) Secondary-paint adhesive properties
An epoxy-phenolic resin was applied to the test material; the rein was baked at
200°C for 30 minutes; then, cross-cut having a depth that reaches a base iron was
applied at 1 mm intervals; a retort process was applied at 125°C for 30 minutes and the
22/39
test piece was dried the coated film was detached with a tape; and, a detached state was
evaluated in four grades (A: No detachment was found, B: Minor detachment occurred
but practically ignorable, C: Minor detachment occurred, and D: Mostly detached).
[0051]
(F) Resistance to corrosion under a coated film
An epoxy-phenolic resin was applied to the test materials; the rein was baked at
200°C for 30 minutes; then, cross-cut having a depth that reaches a base iron was
applied; the test material was immersed in a test solution containing a combination of
1.5% citric acid-1.5% salt at 45°C for 72 hours, and was cleaned; after the test material
was dried, tape detachment was performed; and in terms of corrosion states under
coated film at a cross-cut portion and corrosion states at a flat portion, evaluation was
performed in four grades (A: No corrosion under coated film was found, B: Minor
corrosion under coated film was found but practically ignorable, C: Minor corrosion
under coated film and minor corrosion at flat portion were found, and D: Severe
corrosion under coated film and corrosion at flat portion were found).
[0052]
(G) Non-lacquering corrosion resistance
The test materials were immersed in a 1.5% citric acid solution at 30°C for 48
hours, and uniformity of Sn melting was evaluated by judging occurrence state of tin
crystal in four grades (A: Tin crystal can be clearly found on entire surface, B: Tin
crystal can be found on almost entire surface, C: Tin crystals can partially be found, and
D: Tin crystals can hardly be found).
[0053]
(H) Sulphide staining resistance
The test materials were immersed in a test solution (0.056% cysteine
hydrochloride, 0.4% potassium dihydrogen phosphate, 0.81% sodium phosphate) at
121°C for one hour, and a discoloration (blackening) state was evaluated in four grades
(A: Almost no discoloration was found, B: Minor discoloration was found but
practically ignorable, C: Severe discoloration was partially found, and D: Severe
discoloration was found in a large part).
[0054]
(I) After-retort rust resistance
23 / 39
The test materials were subjected to a retort process at 125°C for 30 minutes,
and a rust occurrence state was evaluated in four grades (A: No rust occurred, B: Minor
rust was found but practically ignorable, C: Minor rust was found, and D: Rust occurred
in a large part).
[0055]
(J) Wettability
A commercially available test solution for wet surface -tension was applied to
the test materials ; evaluation was made on the basis of a limit tensile force of test
solution at which the test solution starts to repel was evaluated; and wettability was
evaluated in three grades (A: 35 mN/m or more, B : 31 mN/m or more, and D: 30 mN/m
or less) based on the magnitude of the tensile force.
24/39
[0056]
[Table 1]
Type of base sheet Method of manufacturing base sheet
Base
Steel sheet Cold rolling - annealing - temper rolling - degreasing - piclding
sheet 1
Base Cold rolling - annealing -,temper rolling - degreasing - pickling
Sn-plated steel sheet
sheet 2 - Sn plating with fenostan bath (amount of Sn ion of 20 g/1)
Base Cold rolling - annealing - temper rolling - degreasing - pickling
Ni-plated steel sheet
sheet 3 - Ni plating with watts bath (amount of Ni ion of 50 g/t)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Ni + So plated steel
- Ni plating with watts bath (amount of Ni ion of 50 g/1)
sheet 4 sheet
- Sn plating with ferrostan bath (amount of Sn ion of 20 g/1)
Cold rolling
Base Ni (diffusion) plated
- Ni plating with watts bath (amount of Ni ion of 50 g/1)
sheet 5 steel sheet
- diffuse Ni through annealing - temper rolling
Cold rolling
Base Ni (diffusion) + So - Ni plating with watts bath (amount of Ni ion cif 50 g/1)
sheet 6 plated steel, sheet - diffuse Ni through annealing - temper rolling
- Sn plating with ferrostan bath (amount of Sn ion of 20 g/1)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Fe-Ni alloy plated
Fe-Ni plating with sulfuric acid-hydrochloric acid bath (amount of
sheet 7 steel sheet
Fe ion 20 g/1, amount of Ni ion 70g/1)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Fe-Ni alloy + Sn - Fe-Ni plating with sulfuric acid-hydrochloric acid bath (amount of
sheet 8 plated steel sheet Fe ion 20 g/1, amount of Ni ion 70g/I)
So plating with ferrostan bath (amount of So ion of 20 g!I)
Cold rolling -annealing -temper rolling - degreasing - pickling
Base Ni-Sn alloy plated
Ni-Sn plating with sulfuric acid-hydrochloric acid bath (amount of
sheet 9 steel sheet
Sn ion 20 g/1, amount of Ni ion 70g/1)
25 / 39
[0057]
[Table 2A]
Base sheet Type of base sheet
Electric heating
+
Hot water cooling
Example 1 Base sheet 1 Steel sheet
Example 2 Base sheet I Steel sheet
Example 3 Base sheet 1 Steel sheet
Example 4 Base sheet I Steel sheet
Example 5 Base sheet 1 Steel sheet
Example 6 Base sheet 1 Steel sheet
Example 7 Base sheet I Steel sheet
Example 8 Base sheet 1 Steel sheet
Example 9 Base sheet 2 Sn-plated steel sheet Applied
Example 10 Base sheet 2 Sn-plated steel sheet
Example 11 Base sheet 2 Sn-plated steel sheet Applied
Example 12 Base sheet 2 Sn-plated steel sheet Applied
Example 13 Base sheet 2 Sn-plated steel sheet Applied
Example 14 Base sheet 2 Sn-plated steel sheet Applied
Example 15 Base sheet 2 Sn-plated steel sheet Applied
Example 16 Base sheet 3 NI-plated steel sheet
Example 17 Base sheet 3 Ni-plated steel sheet
'Example 18 Base sheet 3 Ni-plated steel sheet
Example 19 Base sheet 5 Ni (diffused) plated steel sheet
26 / 39
[0058]
[Table 2B]
Base sheet Type of base sheet
Electric heating
+
Hot water cooling
Example 20 Base sheet 5 Ni (diffused) plated steel sheet
Example 21 Base sheet 7 Fe-Ni alloy plated steel sheet
Example 22 Base sheet 7 Fe-Ni alloy plated steel sheet
Example 23 Base sheet 4 Ni + So plated steel sheet Applied
Example 24 Base sheet 4 Ni + Sn plated steel sheet Applied
Example 25 Base sheet 6 Ni (diffuse) + Sn plated steel sheet Applied
Example 26 Base sheet 6 Ni (diffuse) + Sn plated steel sheet
Example 27 Base sheet 8 Fe-Ni alloy + Sn plated steel sheet Applied
Example 28 Base sheet 8 Fe-Ni alloy + Sn plated steel sheet Applied
Example 29 Base sheet 9 Ni-Sn alloy plated steel sheet
Comp. Example I Base sheet 2 Sn-plated steel sheet Applied
Comp. Example 2 Base sheet 4 Ni + Sn plated steel sheet
Comp. Example 3 Base sheet 1 Steel sheet
Comp. Example 4 Base sheet 3 Ni plated steel sheet
Comp. Example 5 Base sheet 5 Ni (diffused) plated steel sheet
Comp. Example 6 Base sheet 6 Ni (diffused) + Sn plated steel sheet Applied
Comp. Example 7 Base sheet 8 Fe-Ni alloy + Sn plated steel sheet
Comp. Example 8 Base sheet 3 Ni-plated steel sheet
27 / 39
[0059]
Conditions for treatment of composite film
Electrolysis process Components of treatment solution
Process
duration
Electric
current
density
Zr ion
Nitric
acid ion
Ammonium
ion
Phosphoric
acid
Phenolic
resin
Pion So ion Fe ion Ni ion
Water
cleaning
treatment
(Sec) (A/dm2) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)
Example 1 12.9 40.0 4900 17900 20000 - 10200 (a)
Example 2 10.4 16.0 14700 5500 7700 33600 78 18370 (a)
Example 3 3.2 45.0 15500 7300 15900 26800 24490 (a)
Example 4 7.4 9.0 13100 10000 13800 40400 9370 2000 (a)
Example 5 13.9 31.0 18700 13400 10900 - 1050 (a)
Example 6 14.9 16.0 6500 17000 5300 45500 380 (a)
Example 7 19.6 2.0 18200 11500 13800 - 990 10200 20920 (a)
Example 8 4.4 8.0 1900 14600 19400 4600 1500 23700 6140 20390 (a)
Example 9 12.8 9.0 2100 4400 6600 - 150 (a)
Example 10 3.7 42.0 5400 10400 6200 - 640 45 (a)
Example 11 8.9 43.0 11600 19600 13000 34700 1270 (a)
Example 12 13.2 46.0 8700 10300 2900 980 (a)
Example 13 15.4 25.0 300 10100 19500 30300 590 (a)
Example 14 0.9 50.0 10400 13200 10400 4800 700 3050 (a)
Example 15 13.3 31.0 6900 19200 11100 15200 1660 26000 350 420 (a)
Example 16 11.0 23.0 8900 8000 7200 350 (a)
Example 17 18.8 19.0 13800 4900 17100 940 (a)
Example 18 8.2 42.0 8600 4300 5100 33300 24 279 (a)
Example 19 12.6 4.0 11600 10700 7600 410 (a)
28 / 39
[0060]
Conditions for treatment of composite film
Electrolysis process Components of treatment solution
Process
duration
Electric
current
density
Zr ion
Nitric
acid ion
Ammonium
ion
Phosphoric
acid
Phenolic
resin
F ion Sn ion Fe ion Ni ion
Water
cleaning
treatment
(Sec) (A/dm2) (PPm) (ppm) (ppm) (ppm) (ppm) (PPm) (ppm) (ppm)
Example 20 15.9 37.0 15700 19000 4200 16600 190 (a)
Example 21 0.8 30.0 11100 9300 6100 5300 210 650 (a)
Example 22 8.5 19.0 18500 12300 6300 20800 230 27300 3410 22540 (a)
Example 23 17.3 30.0 11600 6700 17900 162 590 (a)
Example 24 0.7 38.0 9400 2400 18200 720 96 (a)
Example 25 14.3 16.0 3700 8000 10300 27400 1942 140 (a)
Example 26 6.6 49.0 9800 13100 2000 193 720 (a)
Example 27 19.5 -42.0 9000 1300 15000 35000 89 150 510 (a)
Example 28 8.6 37.0 4200 19400 1300 26600 1370 630 960 (a)
Example 29 3.0 5.0 11900 12900 20000 48900 1570 3200 204 160 (a)
Comp.Example 1 14.8 43.0 13600 18400 13500 710 (a)
Comp.Example 2 11.4 38.0 15400 19800 1700 83 17190 (a)
Comp.Example 3 8.0 6.0 2700 900 9000 8 (a)
Comp.Example 4 4.2 4.0 2500 5400 1700 41300 7 8 (a)
Comp.Example 5 6.5 7.0 4400 7500 2400 17400 760 9830 (a)
Comp.Example 6 13.2 36.0 16900 7900 17200 19500 12220 570 (a)
Comp.Example 7 18.5 41.0 3600 9200 800 11200 24490 (b)
Comp.Example 8 3.5 47.0 15000 10300 6700 11670 21560 (b)
29 / 39
[0061]
(Table 4A
Attached amount
Amount of Zr
attached
Amount of P
attached
Amount of C
attached
Amount of F
attached
Amount of Sn
attached
Amount of Fe
attached
Amount of Ni
attached
(mg/m2) /(
mg/m2) (mg/m2) /(mg/m2) (mg/m2) (mg/m2) (mg/ml)
Example 1 68.0 19.3
Example 2 21.8 28.4 26 1261
Example 3 61.9 24.5 17.2
Example 4 20.1 11.5 6.3 1127
Example 5 58.8 560
Example 6 35.4 40.8 4.9
Example 7 99.8 23.0 0.07 1391
Example 8 40.2 0.2 37.9 0.09 15.0 142
Example 9 48.3 12.1
Example 10 1.9 0.9 9
Example 11 13.2 1.0 19.1
Example 12 61.2 8.0
Example 13 6.6 9.8 2.3
Example 14 16.2 4.3 0.2 17.6
Example 15 24.6 11.2 12.5 0.08 5.3 1504
Example 16 0.3 1925
Example 17 63.4 51
Example 18 33.3 6.6 11 126
Example 19 1.4 751
30 / 39
[0062]
(Table 4B
Attached amount
Amount of Zr
attached
Amount of P
attached
Amount of C
attached
Amount of F
attached
Amount of Sn
attached
Amount of Fe
attached
Amount of Ni
attached
(mg/m2) (mg/m2) (mg/m) (mg/m2) (mg/mz) (mg/m2) (m€/ n2)
Example 20 6.6 3.6 612
Example 21 8.9 3.9 8.2 1601
Example 22 41.4 30.8 27.1 0.09 17.4 1864
Example 23 73.3 17.5 7.6
Example 24 65.0 3.1 3
Example 25
Example 26
7.5
60.1
2.4 16.1
11.6
7
15.9
Example 27 1.7 32.2 10.2 140 19.3
Example 28 90.2 40.1 1.8 6.5 5
Example 29 46.7 18.1 6.6 0.09 6.9 19
Comp.Fxample 1 115.0 10.5
Comp.Example 2 0.06 17.4 1886
Cornp.Example 3 55.6 0.2
Comp.Example 4 85.7 17.5 3 2
Comp.Example 5 81.8 56.0 58.0 11.1
Comp.Example 6 30.3 7.4 10.7 1789
Comp.Example 7 84.9 0.30 15.8
Comp.Example 8 43.2 9.5 1148
31/39
[0063]
Evaluation
Can-making
workability
Weldability
Film
• adhesive
property
Primary-paint
adhesive
property
Secondary-paint
adhesive
property
Resistance
to
corrosion
under a
coated film
Non-lacquering
corrosion
resistance
Sulphide
staining
resistance
After-retort
rust
resistance
Wettability
Example 1 B B B A B B A A B A
Example 2 A-B A A-B A A-B A-B - A A-B A
Example 3 A-B A A-B A A-B A-B A A A-B A
Example 4 A-B A A-B A A-B A-B A A A-B A
Example 5 A-B A A-B A A-B A-B - A A-B A
Example 6 A A A- A A A A A A A
Example 7 A A A A A A - A A A
Example 8 A A A A A A A , A A A
Example 9 B A B A B B A A B A
Example 10 B A B A B A-B B A B A
Example II A-B A A-B A A-B A-B A A A-B A
Example 12 A-B A A-B A A-B A-B A A A-B A
Example 13 A A A A A A A A A A
Example 14 A A A A A A A A A A
Example 15 A A A A A A A A A A
Example 16 B A B B B B - A B A
Example 17 B B B A B A-B - A B A
Example 18 A-B A A-B A A-B A-B - A A-B A
Example 19 A-B A A-B A A-B A-B A A-B A
32 / 39
[0064]
Evaluation
Can-making
workability
Weldability
Film
adhesive
property
Primary-paint
adhesive
property
Secondary-paint
adhesive
property
Resistance
to
corrosion
under a
coated film
Non-lacquering
corrosion
resistance
Sulphide
staining
resistance
After-retort
rust
resistance
Wettability
Example 20 A A A A A A - A A A
Example 21 A A A A A A - A A A
Example 22 A A A A A A A A A A
Example 23 A A A A A A A A A A
Example 24 A A A A A A-B A A A A
Example 25 A-B A A-B A A-B A-B A A A-B A
Example 26 A-B A A-B A A-B A-B A A A-B A
Example 27 A A A A A A A A A A
Example 28 A A A A A A A A A A
Example 29 A A A A A A A A A A
Comp.Example 1 C D A A A A C-D A A A
Comp.Example 2 D A D D D D A D B C
Comp.Example 3 D D D D D D C B B A
Comp.Example 4 C-D C-D C-D C-D C-D C-D - A A A
Comp.Example 5 D D C-D C-D C-D B C B B A
Comp.Example 6 A D A A A A A A A A
Comp.Example 7 A A A A A D A A D D
Comp. Example 8 A A A A L A A A A A D
33 / 39
[0065]
It can be found that Examples t to 29 according to the present invention
exhibited excellent can-making workability, weldability, film adhesive properties,
primary-paint adhesive properties, secondary-paint adhesive properties, resistance to
corrosion under a coated film, non-lacquering corrosion resistance, sulphide staining
resistance, after-retort rust resistance, and wettability. On the other hand, it was found
that Comparative Examples I to 8, which do not satisfy part of the requirements of the
present invention, were inferior in at least one of the can-making workability, the
weldability, the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, the resistance to "corrosion under a coated film, the
non-lacquering corrosion resistance, the sulphide staining resistance, the after-retort rust
resistance, and the wettability deteriorated.
These are detailed descriptions of preferred embodiments according to the
present invention. However, the present invention is not limited the above-described
examples. It is obvious that a person who has ordinary knowledge in a technical field
to which the present invention belongs is able to reach various modification examples or
adjustment examples within the technical scope set forth in claims, and it should be
understood that these modification examples and adjustment examples naturally belong
to the technical scope of the present invention.
Industrial Applicability
[0066]
The steel sheet for a container according to the present invention exhibits
excellent can-making workability, weldability, film adhesive properties, primary-paint
adhesive properties, secondary-paint adhesive properties, resistance to corrosion under a
coated film, non-lacquering corrosion resistance, sulphide staining resistance,
after-retort rust resistance, and wettability, and in particular, is useful as a steel sheet for
a laminate-filmed container.
Reference Signs List
[0067]
A Cold-rolled steel sheet
34 / 39
B Plating
C Composite film
S Steel sheet for a container
1-9 Base sheet
35 / 39
CLAIMS
1. A steel sheet for a container, the steel sheet comprising
a cold-rolled steel sheet, and
a composite film formed on the cold-rolled steel sheet through an electrolysis
process in a solution containing:
at least one metal ion selected from the group consisting of an Sri ion,
an Fe ion, and an Ni ion;
a Zr ion;
a nitric acid ion; and
an ammonium ion, wherein
the composite film contains at least one element selected from the group
consisting of
Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr:
Sri of 0.3 to 20 g/m2 in equivalent units of metal Sri;
Fe of 5 to 2000 mg/m2 in equivalent units of metal Fe; and
Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
2. The steel sheet for a container according to claim 1, wherein
the solution further contains at least one of a phosphoric acid ion and a
phenolic resin, and
the composite film further contains at least one of a phosphoric acid compound
of 0.1 to 50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50 mg/m2 in
equivalent units of C.
3. The steel sheet for a container according to claim 2, wherein
the solution further contains a fluorine ion, and
the composite film further contains a fluorine compound of not more than 0.1
mg/m2 in equivalent units of F.. °
4. The steel sheet for a container according to any one of claims I to 3, wherein
36 / 39
the cold-roiled steel sheet has at least one side surface including at least one of
an Sn-plated layer containing So of 0.3 to 20 g/m2 in equivalent units of metal Sn, and
an Ni-plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
5. The steel sheet for a container according to claim 4, wherein
the at least one side surface of the cold-rolled steel sheet has the Sn-plated layer,
and
at least part of the Sn-plated layer is alloyed with the cold-rolled steel sheet
through a tin-reflow treatment.
6. The steel sheet for a container according to claim 4, wherein
the at least one side surface of the cold-rolled steel sheet has the Sn-plated layer,
and
there is provided, below the Sn-plated layer, an Ni-plated layer, an Fe-Ni alloy
plated layer, or an Ni-diffusion plated layer obtained through a thermal treatment after
Ni plating.
7. The steel sheet for a container according to claim 6, wherein
the at least one side surface of the cold-rolled steel sheet has the Sn-plated layer,
and
all or part of the Sn-plated layer is alloyed with the cold-rolled steel sheet
through a tin-reflow treatment.
8. A method of manufacturing a steel sheet for a container, including:
applying an electrolysis process to a cold-rolled steel sheet in a solution
containing:
at least one metal ion of an Sn ion, an Fe ion, and an Ni ion;
a Zr ion;
a nitric acid ion, and
an ammonium ion, to precipitate on the cold-rolled steel sheet, and
forming a composite film containing at least one element of.
Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr;
37 / 39
Snof 0.3 to 20 g/m2 in equivalent units of metal Sn;
Fe of 5 to 2000 mg/m2 in equivalent units of metal Fe; and
Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
9. The method of manufacturing a steel sheet for a container according to claim 8,
wherein
the cold-rolled steel sheet has at least one side surface including at least one of
an Sn-plated layer containing Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn, and
an Ni plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
10. The method of manufacturing a steel sheet for a container according to claim 8,
wherein
the solution further contains at least one of a phosphoric acid ion and a
phenolic resin, and
the composite film further contains at least one of a phosphoric acid compound
of 0.1 to 50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50 mg/m2 in
equivalent units of C.
11. The method of manufacturing a steel sheet for a container according to any one
of claims 8 to 10, further including
after the composite film is formed on the cold-rolled steel sheet, applying a
cleaning process of an immersion process or spray process with hot water at not less
than 40°C for not less than 0.5 second.
38 / 39
ABSTRACT
The present invention provides a steel sheet for a container including a
cold-rolled steel sheet and a composite film formed on the cold-rolled steel sheet
through an electrolysis process in a solution containing: at least one metal ion of an Sn
ion, an Fe ion, and an Ni ion; Zr ion; a nitric acid ion: and an ammonium ion, in which
the composite film contains at least one element of: Zr of 0.1 to 100 mg/m2 in
equivalent units of metal Zr; Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn; Fe of
5 to 2000 mg/m2 in equivalent units of metal Fe; and Ni of 5 to 2000 mg/m2 in
equivalent units of metal Ni.
39/39
STEEL SHEET FOR CONTAINER AND METHOD OF MANUFACTURING THE
SAME
Technical Field
[0001]
The present invention relates to a steel sheet for a container used as a material
in can-making, and in particular, exhibiting excellent can-making workability,
weldability, film adhesive properties, primary-paint adhesive properties,
secondary-paint adhesive properties, resistance to corrosion under a coated film,
non-lacquering corrosion resistance, sulphide staining resistance, after-retort rust
resistance, and wettability.
The present application claims priority based on Japanese Patent Application
No. 2010-147860 filed in Japan on June 29, 2010, the disclosures of which are
incorporated herein by reference in their entirety.
Background Art
[0002]
Metal containers used for beverage or food can be broadly categorized into a
two-piece can and a three-piece can. For the two-piece can, which is typified by a DI,
can, drawing and ironing are performed, then, lacquering is applied on the inner surface
side of the can, and lacquering and printing are applied on the outer surface side of the
can. For the three-piece can, lacquering is applied on a surface corresponding to the
inner surface of the can, printing is performed on a surface corresponding to the outer
surface of the can, and then, welding is applied to a body portion of the can.
For both types of cans, the lacquering process is a necessary process performed
before or after the can-making. With regard to lacquering, a solvent-based lacquer or
water-based lacquer is used, and then, baking is performed. Through this lacquering
process, waste materials such as waste solvents resulting from these lacquers are
produced as industrial wastes, and exhaust gas (mainly carbon dioxide) is emitted to the
atmosphere. In recent years, efforts for reducing these industrial wastes and exhaust
gas have been undertaken with the aim of achieving global environmental protection.
Among them, attention has been paid to a technique of laminating films as an
1/39
alternative to the lacquers, and this technique is spreading rapidly.
[0003]
For the two-piece can, there have been provided a large number of inventions
concerning a method of manufacturing a can by laminating films, or other related
methods. These inventions include, for example:
Patent Document 1 "Method of Manufacturing a Drawn and Ironed Can";
Patent Document 2 "Drawn and Ironed Can";
Patent Document 3 "Method of Manufacturing a Deep-drawn Thinned Can"; and
Patent Document 4 "Coated Steel Sheet for a Drawn and Ironed Can".
For the three-piece can, there have been proposed:
Patent Document 5 "Film-layered Steel Strip for Three-piece Can, and a Method of
Manufacturing the Same";
Patent Document 6 "Three-piece Can Having Multiple-layered Organic Film on the
Outer Surface of the Can";
Patent Document 7 "Steel Sheet for a Three-piece Can Having Striped Multiple-layered
Organic Film"; and
Patent Document 8 "Method of Manufacturing a Striped Laminate Steel Sheet for a
Three-piece Can".
[0004]
In many cases, a chromate film subjected to an electrolysis chromate treatment
is used for a steel sheet used as a base for the laminate film. The chromate film has a
two-layered structure including a hydrated Cr oxide layer provided on the upper layer of
a metal Cr layer. This provides the laminate film (adhesive layer in the case where the
film has adhesive agent) with adhesiveness to the steel sheet by way of the hydrated Cr
oxide layer of the chromate film. It is said that this appearance of adhesiveness results
from a hydrogen bond between a hydroxy group of the hydrated Cr oxide and a function
group such as a carbonyl group and an ester group of the laminate film, although details
of a mechanism thereof are not clearly found.
[0005]
Further, a technique employing a Zr compound film in place of the
conventional chromate film includes:
Patent Document 9 "Steel Sheet for a Container Exhibiting Excellent Can-making
2/39
Workability";
Patent Document 10 "Steel Sheet for a Container";
Patent Document 11 "Steel Sheet for a Container"; and
Patent Document 12 "Steel Sheet for a Container Exhibiting Excellent Organic Film
Property, and a Method of Manufacturing the Same".
Related Art Documents
Patent Documents
[0006]
Patent Document 1: Japanese Patent No. 1571783
Patent Document 2: Japanese Patent No. 1670957
Patent Document 3: Japanese Unexamined Patent Application, First Publication
No. H02-263523
Patent Document 4: Japanese Patent No. 1601937
Patent Document 5: Japanese Unexamined Patent Application, First Publication
No. H03-236954
Patent Document 6 : Japanese Unexamined Patent Application, First
Publication No. H05-124648
Patent Document 7 : Japanese Unexamined Patent Application, First
Publication No. H05-111979
Patent Document 8 : Japanese Unexamined Patent Application, First
Publication No. H05-147181
Patent Document 9 : Japanese Unexamined Patent Application, First
Publication No. 2007-284789
Patent Document 10 : Japanese Unexamined Patent Application, First
Publication No. 2009-1852
Patent Document 11 : Japanese Unexamined Patent Application, First
Publication No. 2009-1854
Patent Document 12 : Japanese Unexamined Patent Application, First
Publication No. 2010-13728
Disclosure of the Invention
3/39
Problems to be Solved by the Invention
[0007]
It is true that the above-described inventions are effective in achieving the
global environmental protection. However, in recent years, in the beverage container
industry, competition is fierce among a PET bottle, a glass bottle, paper, and other
materials in terms of cost and quality. Under such a circumstance, there is an
increasing demand for a conventional lacquer applied to the above-described laminate
steel sheet for a container and capable of providing excellent film adhesive properties,
primary-paint adhesive properties, secondary-paint adhesive properties, resistance to
corrosion under a coated film, and non-lacquering corrosion resistance, and providing
further improved can-making workability, film adhesive properties, in particular, film
adhesive properties after working, resistance to corrosion under a coated film, and
non-lacquering corrosion resistance.
[0008]
In particular, for a Zr film, which is a new film and is alternative to the
chromate film, Ni plating or Sri plating is applied, and then, a rinsing treatment for
cleaning a plating solution is applied in a conventional manufacturing method, which
results in formation of hydroxide of Ni or Sri on an Ni- or Sn-plated layer. Thus, even
if the Zr film is formed thereafter, the formed hydroxide film inhibits bonding of the Zr
film with the plating metal, which makes it impossible to achieve sufficient
performances. Further, this phenomenon employs an increase in pH caused by a
hydrogen ion consumption during cathode electrolysis to change a Zr ion into Zr
hydrate, thereby forming the Zr film.' Thus, this method does not have any effect of
cleaning the surface of the plated material, which is an inevitable principle problem.
[0009]
In view of the circumstances described above, the present invention has been
made and an object of the present invention is to provide a steel sheet for a container
formed mainly by a Zr film, which exhibits excellent can-making workability,
weldability, film adhesive properties, primary-paint adhesive properties,
secondary-paint adhesive properties, resistance to corrosion under a coated film,
non-lacquering corrosion resistance, sulphide staining resistance, after-retort rust
resistance, and wettability.
4/39
Means for Solving the Problems
[0010]
The present invention has been made to solve the above-described problem,
and has the following modes.
(1) A first mode of the present invention provides a steel sheet for a container,
including a cold-rolled steel sheet, and a composite film formed on the cold-rolled steel
sheet through an electrolysis process in a solution containing: at least one metal ion of
an Sn ion, an Fe ion, and an Ni ion; a Zr ion; a nitric acid ion; and an ammonium ion, in
which the composite film contains at least one element of Zr of 0.1 to 100 mg/m2 in
equivalent units of metal Zr: Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn; Fe of
5 to 2000 mg/m2 in equivalent units of metal Fe; and Ni of 5 to 2000 mg/m2 in
equivalent units of metal Ni.
(2) According to the steel sheet for a container described in (1) above, the solution
may further contain at least one of a phosphoric acid ion and a phenolic resin, and the
composite film may further contain at least one of a phosphoric acid compound of 0.1 to
50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50 mg/m2 in equivalent
units of C.
(3) According to the steel sheet for a container described in (2) above, the solution
may further contain a fluorine ion, and the composite film may further contain a
fluorine compound of not more than 0.1 mg/m2 in equivalent units of F.
(4) According to the steel sheet for a container described in any one of (1) to (3)
above, the cold-rolled steel sheet may have at least one side surface including at least
one of an Sn-plated layer containing So of 03 to 20 g/m2 in equivalent units of metal Sn,
and an Ni-plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
(5) According to the steel sheet for a container described in (4) above, the at least
one side surface of the cold-rolled steel sheet may have the Sn-plated layer, and at least
part of the Sn-plated layer may be alloyed with the cold-rolled steel sheet through a
tin-reflow treatment.
(6) According to the steel sheet for a container described in (4) above, the at least
one side surface of the cold-rolled steel sheet may have the Sn-plated layer, and there
may be provided, below the Sn-plated layer, a Ni-plated layer, an Fe-Ni alloy plated
5/39
layer, or a Ni-diffusion plated layer obtained through a thermal treatment after Ni
plating.
(7) According to the steel sheet for a container described in (6) above, the at least
one side surface of the cold-rolled steel sheet may have the Sn-plated layer, and all or
part of the Sn-plated layer may be alloyed with the cold-rolled steel sheet through a
tin-reflow treatment.
(8) A second mode of the present invention provides a method of manufacturing a.
steel sheet for a container, including: applying an electrolysis process to a cold-rolled
steel sheet in a solution containing: at least one metal ion of an Sn ion, an Fe ion, and an
Ni ion; a Zr ion; a nitric acid ion, and an ammonium ion, to precipitate on the
cold-rolled steel sheet, and forming a composite film containing at least one element of.
Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr; Sn of 0.3 to 20 g/m2 in
equivalent units of metal Sn; Fe of 5 to 2000 mg/m2 in equivalent units of metal Fe; and
Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
(9) According to the method of manufacturing a steel sheet described in (8) above,
the cold-rolled steel sheet may have at least one side surface including at least one of an
Sn-plated layer containing Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn, and an
Ni-plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
(10) According to the method of manufacturing a steel sheet described in (8) above,
the solution may further contain at least one of a phosphoric acid ion and a phenolic
resin, and the composite film may further contain at least one of a phosphoric acid
compound of 0.1 to 50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50
mg/m2 in equivalent units of C.
(11) According to the method of manufacturing a steel sheet described in any one of
(8) to (10) above, it may be possible to apply a cleaning process of an immersion
process or spray process with hot water at not less than 40°C for not less than 0.5
second after the composite film is formed on the cold-rolled steel sheet.
Effects of the Invention
[0011]
According to the present invention, it is possible to obtain a steel sheet for a
container having excellent properties suitable for a can, and exhibiting excellent
6/39
can-making workability, weldability, film adhesive properties, primary-paint adhesive
properties, secondary=paint adhesive properties, resistance to corrosion under a coated
film, non-lacquering corrosion resistance, sulphide staining resistance, after-retort rust
resistance, and wettability.
Brief Description of the Drawings
[0012]
FIG. 1 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 1.
FIG. 2 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 2.
FIG 3 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 3.
FIG. 4 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 4.
FIG 5 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 5.
FIG. 6 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 6.
FIG 7 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 7.
FIG. 8 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet S.
FIG. 9 is a diagram illustrating a configuration of a steel sheet S for a container
using a base sheet 9.
Embodiments of the Invention
[0013]
The present inventors made a keen study of how to make full use of a Zr film,
which is a new film alternative to a chromate film. As a result, the present inventors
found that, by applying an electrolysis process with a treatment solution containing, for
example, an Sri ion or an Ni ion to form a Zr film or a Zr film having a phosphoric acid
7/39
film or phenolic resin film combined with the Zr film, it is possible to simultaneously
precipitate the Zr filni and the film of Sn or Ni, thereby significantly improving
properties for a can such as a film adhesive properties and resistance to corrosion under
a coated film. It is considered that this is because the bonding with the surface of a
material to be treated is strengthened, by precipitating, along with the Zr film, a metal
existing in the surface of a plating layer formed by Ni or Sri.
The present inventors also found that, with the presence of a Cr ion in a
treatment solution, a chromate film is formed before the simultaneous precipitation of
the Zr film and Sri or Ni through the electrolysis process, inhibiting the formation of the
Zr film. Thus, it is necessary to remove the Cr ion in the treatment solution.
[0014]
Hereinbelow, a steel sheet for a can according to an embodiment of the present
invention based on the above-described findings will be described.
[0015]
The steel sheet for a container according to this embodiment provides a steel
sheet for a can obtained by plating a cold-rolled steel sheet or a steel sheet with at least
one metal of Sri, Fe and Ni (hereinafter, collectively referred to as "base sheet"), and
subjecting the base sheet to an electrolysis process in a solution containing: at least one
metal ion of an Sri ion, an Fe ion, and an Ni ion; a Zr ion; a nitric acid ion; and an
ammonium ion, thereby forming a composite film containing the above-described
metallic element on the base sheet. The composite film contains:
(1) Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr, and
(2) at least one element of Sri of 0.3 to 20g/m2 in equivalent units of metal Sri, Fe of 5 to
2000 mg/m2 in equivalent units of metal Fe, and Ni of 5 to 2000 mg/m2 in equivalent
units of metal Ni.
[0016]
The steel sheet for a container according to this embodiment has, on the base
sheet, a composite film containing (1) predetermined amount of Zr and (2)
predetermined amount of at least one element of Sri, Fe, and Ni. More specifically, as
described later, each of the elements constituting the composite film contributes to
improving at least one properties of the can-making workability, the weldability, the
film adhesive properties, the primary-paint adhesive properties, the secondary-paint
8/39
adhesive properties, the resistance to corrosion under a coated film, the non-lacquering
corrosion resistance, the sulphide staining resistance, the after-retort rust resistance, and
the wettability.
It should be noted that it is only necessary that the "composite film" contains
the above-described metallic elements, and formation thereof is not limited. In other
words, each of the metallic elements may be contained as a single-element metal, or
maybe contained as alloys of the metallic elements, or as a compound such as oxide,
hydroxide, halide, and phosphoric acid compounds partially containing the metallic
element.
Further, the composition of the composite film may not be uniform. The
composite film may have a layered structure in which each constituent element or part
of the constituent elements is separated, or constituent elements may form a gradation in
a film-thickness direction.
[0017]
According to the present invention, there is not any particular limitation to the
base sheet. It may be possible to use a steel sheet normally used as a material for a
container. Further, there is not any particular limitation to a material or a method for
manufacturing the base sheet. The base sheet is manufactured through normal
processes used for manufacturing the steel sheet, and then applying hot rolling, pickling,
cold rolling, annealing, temper rolling, or other processes. In the case where a
surface-treated layer containing one or more elements of Ni and Sn is added to the base
sheet, there is not any particular limitation to the addition method. For example, it
may be possible to use a publicly known technique such as electroplating, vacuum
deposition and sputtering, or use a combination of heating treatments for adding a
diffusion layer. Further, the nature of the present invention remains unchanged if
Fe-Ni alloy plating is applied for Ni.
In order to form a high-quality composition layer, it is preferable that the base
sheet is a steel sheet obtained by, before Sn plating, applying an Ni-plated layer, an
Fe-Ni alloy plated layer, and an Ni-diffusion plated layer through a thermal treatment
applied after the Ni plating, and it is more preferable that the base sheet is obtained by,
after the Sn plating, alloying all or part of the Sn plating with a base metal through a
tin-reflow treatment.
9/39
[0018]
According to the steel sheet for a container according to this embodiment, a
composite film is formed on the upper layer of the above-described steel sheet (base
sheet). The thickness of the base sheet (base steel sheet) is determined depending on
applications.
Next, roles of the metals constituting the composite film will be described.
[0019]
Zr is an essential component for the composite film of the steel sheet for a
container according to this embodiment.
In the composite film, Zr contributes to obtaining the film adhesive properties,
the primary-paint adhesive properties, the secondary-paint adhesive properties, the
resistance to corrosion under a coated film, and the non-lacquering corrosion resistance.
Additionally, Zr also contributes to preventing sulfuration and blackening with which a
sulfur compound existing in contents reacts with the base steel, Sn and Ni to form black
sulfides. Zr forms Zr oxide, Zr hydroxide, Zr fluoride, Zr phosphate or other Zr
compound, or composites thereof. These Zr compounds exhibit excellent film
adhesive properties, primary-paint adhesive properties, secondary-paint adhesive
properties, resistance to corrosion under a coated film, non-lacquering corrosion
resistance, and sulphide staining resistance.
When Zr in the composite film reaches 0.1 mg/m2 or more in terms of metal Zr
amount, the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, the resistance to corrosion under a coated film, and
the non-lacquering corrosion resistance start to improve. However, in practice, it is
preferable to set Zr to 1 mg/m2 or more in equivalent units of metal Zr to obtain the
stable and adequate corrosion resistance and the adhesiveness.
Further, with the increase in the amount of Z in the composite film, the effect
of improving the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, the resistance to corrosion under a coated film, and
the non-lacquering corrosion resistance increases. However, in the case where the
amount of Zr exceeds 100 mg/m2 in equivalent units of metal Zr, the film adhesive
properties, the primary-paint adhesive properties, and the secondary-paint adhesive
properties of the composite film itself deteriorate, and the electric resistance increases,
10/39
deteriorating weldability. Further, the excellent non-lacquering corrosion resistance
resulting from the sacrificial protection by metal Sn is impaired, and uniform solubility
of Sn in the contents containing organic acid is inhibited. For these reasons, it is
necessary to set the amount of attached Zr film to be in the range of 0.1 to 100 mg/m2 in
terms of metal Zr amount.
[0020]
As described above, the composite film contains at least one element of So, Fe,
and Ni. Next, preferable amount of each of the elements contained will be described.
[0021]
[Sn: 0.3 to 20 g/m2 in equivalent units of metal Sn]
Sn is normally contained in the composite film in a form of a metal or alloy.
However, So maybe contained in a form of a compound such as an oxide. Sn
provides excellent can-making workability, resistance to corrosion under a coated film,
non-lacquering corrosion resistance, and weldability. To achieve these effects, it is
necessary for the composite film to contain So of 0.3 g/m2 or more in the form of metal
Sn. It is desirable for the composite film to contain Sn of 0.5 g/m2 or more in
equivalent units of metal Sn to obtain rapid and sufficient weldability, and So of 2 g/m2
or more in equivalent units of metal So to obtain sufficient non-lacquering corrosion
resistance. With the increase in the amount of So attached, the effects obtained from,
Sn of providing improved can-making workability, resistance to corrosion under a
coated film, non-lacquering corrosion resistance, and weldability increase. However,
in the case where the amount of Sn exceeds 20 g/m2, the effect of Sn saturates, and the
excessive amount of Sn leads to an economic disadvantage. Thus, the amount of So
attached may be set to 20 g/m2 or less in equivalent units of metal Sn. Further, by
applying Sn reflow treatment (tin-reflow treatment) after the Sn plating, an So alloy
layer is formed, thereby further improving the corrosion resistance.
[0022]
[Fe: 5 to 2000 mg/m2 in equivalent units of metal Fe]
Fe is normally contained in the composite film in a form of a metal or alloy.
However, Fe may be contained in a form of a compound such as an oxide. Fe provides
excellent weldability. To obtain this effect, it is necessary for the composite film to
contain Fe of 5 mg/m2 or more in equivalent units of metal Fe. With the increase in
11/39
the amount of Fe attached, the effect of improving the weldability increases. However,
in the case where the amount of Fe exceeds 2000 mg/M2, the effect of improving the
weldability saturates, and the excessive amount of Fe leads to an economic
disadvantage. Thus, the amount of Fe attached is set to be not less than 5 mg/m2 and
not more than 2000 mg/m2 in equivalent units of metal Fe.
[0023]
[Ni: 5 to 2000 mg/m2 in equivalent units of metal Ni]
Ni is normally contained in the composite film in a form of a metal or alloy.
However, Ni may be contained in a form of a compound such as an oxide. Ni has an
effect on the primary-paint adhesive properties, the secondary-paint adhesive properties,
the film adhesive properties, the resistance to corrosion under a coated film, and the
weldability. To achieve these effects, it is necessary for the composite film to contain
Ni of 5 mg/m2 or more in equivalent units of metal Ni. To obtain rapid and sufficient
weldability and sufficient resistance to corrosion under a coated film, it is desirable to
add Ni of 150 mg/m2 or more. With the increase in the amount of Ni attached, the
excellent effect obtained from Ni of improving the film adhesive properties, the
resistance to corrosion under a coated film, and the weldability increases. However, in
the case where the amount of Ni exceeds 2000 mg/m2 or more, the effect of improving
these properties saturates, and the excessive amount of Ni leads to an economic
disadvantage. Thus, the amount of Ni attached is set to be not less than 5 mg/m2 and
not more than 2000 mg/m2 in equivalent units of metal Ni.
[0024]
It should be noted that, in the case where the composite film contains Cr, an
improvement in the resistance to corrosion under a coated film can be expected.
However, as described above, with the existence of a Cr ion in the treatment solution,
before the Zr film and Sn, Ni, or other element are simultaneously precipitated, a
chromate film is formed through the electrolysis process, whereby the formation of the
Zr film is inhibited. This leads to a deterioration in performances such as weldability.
Thus, according to the present invention, it is preferable that the composite film does
not contain Cr.
[0025]
As a method for adding the composite film described above on the base sheet,
12/39
there is a method of applying a cathodic electrolysis process (hereinafter, also simply
referred to as "electrolysis process") in a solution containing: at least one metal ion of
an Sri ion, an Fe ion, and an Ni ion; a Zr ion; a nitric acid ion; and an ammonium ion.
It is preferable that, in particular, the electrolysis process is performed under conditions
in which these elements are precipitated simultaneously.
It should be noted that there is a method of simply immersing the steel sheet in
the solution described above to form the film. However, with this immersion method,
the base is subjected to etching to form the Zr film, and attachment does not uniformly
occur, which makes it difficult to form the composite film of the steel sheet for a
container according to this embodiment.
With the cathodic electrolysis process, electric charges are forcibly moved, pH
increases due to hydrogen ion consumption at an interface of the steel sheet. Further,
the Zr film has an attachment-facilitating effect. These make it possible to obtain an
uniform film through a process applied within a short period of time ranging from
several seconds to several tens of seconds, which provides significant industrial
advantage. Further, a nitric acid ion is reduced through the cathode electrolysis, a
hydroxide ion is discharged, whereby pH of the interface of the steel sheet is more
likely to increase. When insoluble anode is used, an ammonium ion is reduced to be a
nitrous acid ion or nitric acid ion to supply the nitric acid ion consumed at the cathode,;.
and pH is made stable, which are also advantages of the cathodic electrolysis process.
[0026]
It should be noted that, according to the steel sheet for a container according to
this embodiment, it is preferable that the composite film is formed by:
(1) a Zr film layer formed mainly by Zr, and
(2)'a film layer formed mainly by at least one element of Sri, Fe, and Ni, and,
the surface of the composite film is formed by the (1) Zr film layer formed mainly by
Zr.
More specifically, it is preferable that, by applying an electrolysis process to a
base sheet in a solution containing: at least one metal ion of Sri ion, Fe ion, and Ni ion;
Zr ion; nitric acid ion; and ammonium ion to form a composite film containing
compounds of the metals described above on the base sheet, the steel sheet for a
container has the composite film configured such that a film layer formed mainly by at
13/39
least one element of Sn, Fe, and Ni is formed on a base sheet, and above the film layer,
a Zr film layer formed mainly by Zr is formed, in other words, the composite film has a
gradation of metal elements constituting the film.
[0027]
Further, in the steel sheet for a container according to the present invention,
from the viewpoint of enhancing the film adhesive properties between the composite
film and the base sheet after working, it is preferable that the composite film contains:
(1) Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr,
(2) Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn, Fe of 5 to 2000 mg/r2 in terms
of metal Fe amount, and Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni, and
(3) at least one of a phosphoric acid compound of 0.1 to 50 mg/m2 in equivalent units of
P and a phenolic resin of 0.1 to 50 mg/m2 in equivalent units of C.
The composite film containing (3) at least one of the phosphoric acid and the
phenolic resin can be obtained by applying an electrolysis process to a steel sheet in a
solution in which at least one of fluorine ion, phosphoric acid ion, and phenolic resin is
further added to the above-described solution.
It should be noted that the composite film containing (3) at least one of the,
phosphoric acid and the phenolic resin can be formed by applying the electrolysis
process in a similar manner as described above.
[0028]
The fluorine ion forms a complex, and contributes to stabilization of the Zr ion.
Thus, by adding the fluorine ion for the purpose of stabilizing Zr in an electrolyte
solution (forming chelate and diffusing), the allowable range of pH, concentration and
temperature increases, which makes operations easy.
However, when absorbed in the composite film, F causes a deterioration in the
adhesiveness (secondary adhesive properties) or after-retort rust resistance in a
high-temperature sterilization process such as a retort process, or resistance to corrosion
under a coated film, although not having any effect on the normal adhesiveness
(primary adhesive properties) of paint or film. It is considered that this is because the
fluorine ion in the film elutes to steam or etching solution, decomposes the bonding
with the organic film or corrodes the base steel sheet. Thus, in the case where the
amount of fluorine compound contained in the composite film exceeds 0.1 mg/m2 in
14/39
equivalent units of F, the deterioration in these properties becomes apparent. For these
reasons, the amount of fluorine compound contained in the composite film is set
preferably to 0.1 mg/mz or less in equivalent units of F.
[0029]
It should be noted that, in the case where the fluorine remains in the composite
film as described above, the film adhesive properties, the secondary-paint adhesive
properties and other properties deteriorate. Thus, when used, the fluorine needs to be
removed as much as possible with hot-water cleaning. The fluorine needs to be
removed as much as possible with hot-water cleaning immediately after the composite
film is formed. The purpose of cleaning with the hot water is to clean the treatment
solution and improve the wettability. In particular, cleaning with the hot water
improves the wettability, and hence, suppresses occurrence of pinholes caused by
repellence of lacquer. This significantly improves the lacquering properties,
contributing to securing quality of the lacquered steel sheet. In order to sufficiently
obtain the wettability, the surface tension of 31 mlv/m or more is necessary, and the
surface tension of 35 mN/m or more is preferable. The surface tension in this
specification is a value measured with a method specified in JIS K 6768. Under this
standard, test solutions having various surface tensions are applied, and measurement is
performed in a Wet condition with the test solutions. Thus, if the wet condition with,
the test solution having high surface tension is favorable, the composite film has
excellent wettability. Thus, the wettability can be evaluated in association with the
surface tension of the test solution.
[0030]
Although details of how this hot-water cleaning improves the wettability are
not known, it is considered that this is because hydrophilic functional groups increase in
the outermost layer of the film. To achieve these effects, it is necessary to apply a
cleaning process including an immersion process or spray process with hot water at
40°C or more for 0.5 sec or more. From the industrial viewpoint, it is preferable to
apply the spray process from which the cleaning-facilitating effect resulting from
flowing of liquid is expected, or a combination of the spray process and the immersion
process.
[0031]
15/39
Further, the effect of the hot-water cleaning includes removal of the fluorine
ion entering the composite film in the case where the solution contains the fluorine ion.
As described above, fluorine entering the composite film may deteriorate the film
adhesive properties, the secondary-paint adhesive properties and the after-retort rust
resistance, or the resistance to corrosion under a coated film of the composite film. To
set the amount of fluorine compound contained to be not more than 0.1 mg/m2 in
equivalent units of F to avoid such a deterioration, it is only necessary to apply the
cleaning process including the immersion process and/or spray process using the hot
water after the formation of the composite film. Further, by setting the process
temperature higher or setting the process duration longer, it is possible to reduce the
amount of F. Thus, to set the amount of fluorine compound contained in the film to be
not more than 0.1 mg/m2 in equivalent units of F, it is only necessary to apply the
immersion process or spray process with hot water at 40°C or more for 0.5 sec or more.
In the case where the water temperature is less than 40°C or the process duration is less
than 0.5 sec, the amount of fluorine compound contained in the composite film cannot
be reduced to be 0.1 mg/m2 or less in equivalent units of F, so that the properties
described above cannot be achieved.
[0032]
The purpose of adding the phosphoric acid compound to the composite film is
to obtain the film adhesive properties, the primary-paint adhesive properties, the
secondary-paint adhesive properties, and in particular, the film adhesive properties after
working. The phosphoric acid compound includes Fe phosphate which is formed
through reaction with the base sheet,'Sn phosphate, Ni phosphate and Zr phosphate, a
film such as the phosphate-phenolic resin film, and a composite thereof. These
phosphoric acid compounds have excellent resistance to corrosion under a coated film,
film adhesive properties, primary-paint adhesive properties, and secondary-paint
adhesive properties. Thus, with the increase in the phosphoric acid compound, the
resistance to corrosion under a coated film, the film adhesive properties, primary-paint
adhesive properties, and the secondary-paint adhesive properties increase. Then, if the
phosphoric acid compound in the composite film reaches 0.1 mg/m2 or more in
equivalent units of P, it is possible to obtain the practically adequate level of the
resistance to corrosion under a coated film, the film adhesive properties, the
16/39
primary-paint adhesive properties, and the secondary-paint adhesive properties.
Further, with the increase in the amount of phosphoric acid compound, the effect of
improving the resistance to corrosion under a coated film, the film adhesive properties,
the primary-paint adhesive properties, and the secondary-paint adhesive properties also
further increases. However, in the case where the amount of phosphoric acid
compound exceeds 50 mg/m2 in equivalent units of P, the amount of phosphoric acid
compound is undesirably high, deteriorating the film adhesive properties, the
primary-paint adhesive properties, and the secondary-paint adhesive properties of the
composite film. Further, the electrical resistance increases, deteriorating the
weldability. For these reasons, it is preferable to set the amount of phosphate in the
range of 0.1 to 50 mg/m2 in equivalent units of P.
[0033]
In the composite film, the phenolic resin film contributes to obtaining the film
adhesive properties, the primary-paint adhesive properties, the secondary-paint adhesive
properties, and in particular, the film adhesive properties after working. Since the
phenolic resin is an organic substance, the phenolic resin itself has extremely excellent
adhesiveness to the paint and the laminate film. In the case where the surface-treated
layer is subjected to working such that the surface-treated layer largely deforms,
cohesive failure occurs in the surface-treated layer itself due to the working, possibly
deteriorating the adhesiveness. However, the phenolic resin has an effect of
significantly improving the adhesiveness after the working of the composite film.
Thus, with the increase in the phenolic resin, the film adhesiveness, the primary-paint
adhesive properties, and the secondary-paint adhesive properties further improve. In
the case where the amount of phenolic resin in, the composite film reaches 0.1 mg/m2 or
more in equivalent units of C, it is possible to secure the practically adequate level of
adhesiveness. Further, with the increase in the amount of phenolic resin, the effect of
improving the film adhesiveness, the primary-paint adhesive properties and the
secondary-paint adhesive properties further increases. However, in the case where the
amount of phenolic resin in the composite film exceeds 50 mg/m2 in equivalent units of
C, the electrical resistance increases, deteriorating the weldability. Thus, it is
preferable to set the amount of phenolic resin to be in the range of 0.1 to 50 mg/m2 in
equivalent units of C.
17/39
[0034]
The phenolic resin used in the steel sheet for a container according to this
embodiment includes, for example, a polymer expressed by following Formula (1).
This can be manufactured by forming condensation polymer of phenolic compound,
naphthol compound or bisphenols (bisphenol A or F), and formaldehyde , and then
introducing functional groups X' and X2 using formaldehyde and amine . Formalin is
generally used as the formaldehyde . Although the molecular weight of the polymer is
not particularly limited , the molecular weight is set generally in the range of
approximately 1000 to 1000000 , preferably in the range of approximately 1000 to
100000, more preferably in the range of approximately 1000 to 10000. The molecular
weight can be measured with a gel permeation chromatography after the film is
detached.
[Formula 1]
(1)
In Formula (I), X1 independently represents a hydrogen atom or Z' group
expressed by following Formula (II) in each structural unit, Y' represents a hydrogen
atom, a hydroxy group, an alkyl group with C1 to C5, a hydroxy alkyl group with C1 to
C5, an aryl group with C6 to C12, a benzyl group, or a group expressed by following
Formula (III), and Y2 represents a hydrogen atom . Further, in the case where Y2 exists
adjacent to Y1> Y' and Y2 may integrally form ;a condensed benzene ring including a
bonding between Y' and Y2. In this specification, the ratio of Z1 group + Z2 group
introduced is 0.2 to 1.0 piece per benzene ring.
[00351
[Formula 2]
Z`=-CIS.-I'
R'
In Formula (II), R1 and R2 independently represent a hydrogen atom, an alkyl
group with C1 to C i o or hydroxy alkyl group with C1 to CIo.
18139
[0036]
[Formula 3]
- c -rn --on on)
In Formula (III), R3 and R4 independently represent a hydrogen atom, an alkyl
group with Ci to Cio, or hydroxy alkyl group with C1 to Clo. In the case where Y1 is a
group expressed by Formula (111) described above, X2 represents a hydrogen atom or Z2
group expressed by General Formula (IV) in each structural unit expressed by Formula
M.
[0037]
[Formula 4]
B'
Z2 CH.- (IV)
RR
In Formula (IV), R5 and R6 independently represent a hydrogen atom, an alkyl
group with C1 to CIO, or a hydroxy alkyl group with CI to C1o.
[0038]
It should be noted that, for the steel sheet for a container according to this
embodiment, it may be possible to measure the amount of Sn, the amount of Ni, the
amount of Fe, the amount of Zr, the amount of P, and the amount of F contained in the
composite film, for example, through a quantitative analysis method such as fluorescent
X-ray analysis. Further, in the case where a metal same as that forming the steel sheet
to be treated (base sheet) is attached, it is only necessary to apply the treatment to a
different metal sheet such as a copper sheet, and perform the measurement. Further,
the: amount of C contained in the phenolic resin film can be measured by subtracting the
amount of C existing in the steel sheet using a total organic carbon analyzer (TOC).
[0039]
Depending on manufacturing facility or manufacturing speed (ability),
concentrations of ions in the treatment solution used in the cathodic electrolysis process
for forming the composite film may be adjusted so as to be:
concentration of Sn ion, Fe ion, and Ni ion: approximately 10 to 30000 ppm;
concentration of Zr ion: approximately 100 to 20000 ppm;
19/39
concentration of ammonium ion: approximately 100 to 20000 ppm;
concentration of nitric acid ion: approximately 100 to 20000 ppm;
concentration of phosphoric acid ion: approximately 100 to 50000 ppm;
concentration of phenolic resin: approximately 50 to 2000 ppm; and
concentration of fluorine ion: approximately 500 to 30000 ppm.
Examples
[0040]
Next, using Examples, the present invention will be described more in detail.
However, the present invention is not limited to these Examples, and various
modifications are possible within the scope of the present invention.
[0041]
[Manufacture of base sheet]
Table I shows methods of manufacturing base sheets 1 to 9 having a thickness
in the range of 0.15 to 0.25 mm used in Examples 1 to 19 and Comparative Examples 1
to 8, FIG. I to FIG 9 are diagrams illustrating configurations of steel sheets S for a
container used for the base sheets 1 to 9. In the drawings, numbers I to 9 represent a
base sheet number, A represents a cold-rolled steel sheet, B represents plating, C
represents a composite film, and S represents a steel sheet for a container. Note that,,in
the drawings, at least part of an Sn-plated layer may be alloyed with a cold-rolled steel
sheet through a tin-reflow treatment.
[0042]
Further, Table 2A and Table 2B show base sheets used for Examples 1 to 19
and Comparative Examples l to 8. Note that, in Examples 9, 11 to 15, 23 to 25, 27
and 28, and Comparative Example 1 and Comparative Example 6, after the Sri plating,
electric heating was applied to melt Sri, and then a cooling treatment was applied by
immersing the sheets in hot water at 80°C.
[0043]
[Formation of composite film]
Next, a composite film was added to the surface of each of the base sheets
under conditions for treatment of composite films shown in Table 3A and Table 3B.
More specifically, in a state where the base sheets were immersed in the treatment
20 / 39
solution having an appropriate amount of chemical agents described below, a cathodic
electrolysis process was performed on the basis of the electrolysis process duration and
electric current density shown in Table 3A and Table 3B, thereby forming the composite
film.
The chemical agents used include commercially available Zr nitrate, Zr
ammonium fluoride, hydrofluoric acid, ammonia nitrate, Sn nitrate, Fe nitrate, Ni nitrate,
and phosphoric acid.
Further, as for a low-molecular phenolic resin, a low-molecular phenolic resin
having an average molecular weight of 3000, which is a polymer having Z1=
-CH2N(CH3)2 for X1, Y1= Y2 = hydrogen atom, and a ratio of Z' group introduced of
0.5 piece per benzene ring in the general Formula (I) described above, was used in a
form of water-soluble polymer having a solid content of 2.0 g/L and pH of 6.0 (adjusted
with phosphoric acid).
[0044]
[Rinsing treatment]
After the composite film was formed through the above-described processes, a
rinsing treatment was applied through the following treatment method (a) or (b) to
control the amount of F in the composite film.
(a) Immersing the composite film in hot water at 40°C or more.
(b) Immersing the composite film in water at ordinary temperature of
approximately 15°C.
[0045]
[Performance evaluation]
For test materials having the above-described treatments applied thereto, the
amount of Zr, P, C, F, Sn, Fe, and Ni attached to the composite film was measured.
The results of the measurement are shown in Table 4A and Table 4B. Further,
performance evaluation on the following items (A) to (J) was performed. The results
of the evaluation are shown in Table 5A and Table 5B.
[0046]
(A) Can-making workability
A PET film having a thickness of 20 pm was laminated on both sides of the test
material at 200°C; can-making working was performed sequentially through drawing
21/39
and ironing; and formed items were evaluated in four grades (A: Excellent, B: Good, C:
Defect occurred, and D: Broken and unable to continue working).
[0047]
(B) Weldability
Under conditions of welding wire speed of 80 m/min, the test materials were
welded with a wire seam welder while electric current were varied. Then, weldability
was systematically evaluated in four grades (A: Excellent, B: Good, C: poor, and D:
Unable to weld) based on the appropriate electrical-current range including the
minimum electrical-current value at which the sufficient welding strength can be
obtained, and the maximum electrical-current value at which welding defects such as
spatter and welding spatter start to become conspicuous.
[0048]
(C) Film adhesive properties
A PET film having a thickness of 20 μm was laminated on both sides of the test
material at 200°C; the test material was subjected to drawing-ironing to form a can
body; the can body was subjected to a retort process at 125°C for 30 minutes; and the
film detachment state was evaluated in four grades (A: No detachment was found, B:
Minor detachment occurred but practically ignorable, C: Minor detachment occurred,
and D: Most part was detached).
[0049]
(D) Primary-paint adhesive properties
An epoxy-phenolic resin was applied to the test material; the rein was baked at
200°C for 30 minutes; then, cross-cut having a depth that reaches a base iron was
applied at 1 mm intervals; the resin was detached with a tape; and, a detached state was
evaluated in four grades (A: No detachment was found, B: Minor detachment occurred
but practically ignorable, C: Minor detachment occurred, and D: Most part was
detached).
[0050]
(E) Secondary-paint adhesive properties
An epoxy-phenolic resin was applied to the test material; the rein was baked at
200°C for 30 minutes; then, cross-cut having a depth that reaches a base iron was
applied at 1 mm intervals; a retort process was applied at 125°C for 30 minutes and the
22 / 39
test piece was dried; the coated film was detached with a tape; and, a detached state was
evaluated in four grades (A: No detachment was found, B: Minor detachment occurred
but practically ignorable, C: Minor detachment occurred, and D: Mostly detached).
[0051]
(F) Resistance to corrosion under a coated film
An epoxy-phenolic resin was applied to the test materials; the rein was baked at
200°C for 30 minutes; then, cross-cut having a depth that reaches a base iron was
applied; the test material was immersed in a test solution containing a combination of
1.5% citric acid-1.5% salt at 45°C for 72 hours, and was cleaned; after the test material
was dried, tape detachment was performed; and in terms of corrosion states under
coated film at a cross-cut portion and corrosion states at a flat portion, evaluation was
performed in four grades (A: No corrosion under coated film was found, B: Minor
corrosion under coated film was found but practically ignorable, C: Minor corrosion
under coated film and minor corrosion at flat portion were found, and D: Severe
corrosion under coated film and corrosion at flat portion were found).
[0052]
(G) Non-lacquering corrosion resistance
The test materials were immersed in a 1.5% citric acid solution at 30°C for 48
hours, and uniformity of Sn melting was evaluated by judging occurrence state of tin
crystal in four grades (A: Tin crystal can be clearly found on entire surface, B: Tin
crystal can be found on almost entire surface, C: Tin crystals can partially be found, and
D: Tin crystals can hardly be found).
[0053]
(H) Sulphide staining resistance
The test materials were immersed in a test solution (0.056% cysteine
hydrochloride, 0.4% potassium dihydrogen phosphate, 0.81% sodium phosphate) at
121°C for one hour, and a discoloration (blackening) state was evaluated in four grades
(A: Almost no discoloration was found, B: Minor discoloration was found but
practically ignorable, C: Severe discoloration was partially found, and D: Severe
discoloration was found in a large part).
[0054]
(I) After-retort rust resistance
23 / 39
The test materials were subjected to a retort process at 125°C for 30 minutes,
and a rust occurrence state was evaluated in four grades (A: No rust occurred, B: Minor
rust was found but practically ignorable, C: Minor rust was found, and D: Rust occurred
in a large part).
[0055]
(J) Wettability
A commercially available test solution for wet surface-tension was applied to
the test materials; evaluation was made on the basis of a limit tensile force of test
solution at which the test solution starts to repel was evaluated; and wettability was
evaluated in three grades (A: 35 mN/m or more, B: 31 mN/m or more, and D: 30 mN/m
or less) based on the magnitude of the tensile force.
24 / 39
[0056]
[Table 1]
Type of base sheet Method of manufacturing base sheet
Base
Steel sheet Cold rolling - annealing - temper rolling - degreasing - pickling
sheet I
Base Cold rolling - annealing - temper rolling - degreasing - picking
Sn-plated steel sheet
sheet 2 - Sn plating with ferrostan bath (amount of Sn ion of 20 g/1)
Base Cold rolling - annealing - temper rolling - degreasing - pickling
Ni-plated steel sheet
sheet 3 - Ni plating with watts bath (amount of Ni ion of 50 g/1)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Ni + Sn plated steel
Ni plating with watts bath (amount of Ni ion of 50 g /1)
sheet 4 sheet
- Sn plating with ferrostan bath (amount of Sn ion of 20 g/1)
Cold rolling
Base Ni (diffusion) plated
- Ni plating with watts bath (amount of Ni ion of 50 g/1)
sheet 5 steel sheet
- diffuse Ni through annealing - temper rolling
Cold rolling
Base Ni (diffusion) + Sn - Ni plating with watts bath (amount of Ni ion of 50 g/1)
sheet 6 plated steel sheet - diffuse Ni through annealing - temper rolling
- So plating with ferrostan bath (amount of Sn ion of 20 g/1)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Fe-Ni alloy plated
Fe-Ni plating with sulfuric acid-hydrochloric acid bath (amount of
sheet 7 steel sheet
Fe ionn20 g/l, amount of Ni ion 70g/1)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Fe-Ni alloy + Sn - Fe-Ni plating with sulfuric acid-hydrochloric acid bath (amount of
sheet 8 plated steel sheet Fe ion 20 gll, amount of Ni ion 70g/1)
- Sn plating with ferrostan bath (amount of Sn ion of 20 g/1)
Cold rolling - annealing - temper rolling - degreasing - pickling
Base Ni-Sn alloy plated
- NiTSn plating with sulfuric acid-hydrochloric acid bath (amount of
sheet 9 steel sheet
So ion 20 g/l, amount of Ni ion 70g/1)
25/39
[0057]
[Table 2A]
I
Base sheet Type of base sheet
Electric heating
4
Hot water cooling
Example 1 Base sheet 1 Steel sheet
Example 2 Base sheet 1 Steel sheet
Example 3 Base sheet 1 Steel sheet
Example 4 Base sheet 1 Steel sheet
Example 5 Base sheet 1 Steel sheet
Example 6 Base sheet 1 Steel sheet
Example 7 Base sheet 1 Steel sheet
Example 8 Base sheet 1 Steel sheet
Example 9 Base sheet 2 Sn-plated steel sheet Applied
Example 10 Base sheet 2 Sn-plated steel sheet
Example 11 Base sheet 2 Sn-plated steel sheet Applied
Example 12 Base sheet 2 Sn-plated steel sheet Applied
Example 13 Base sheet 2 Sn-plated steel sheet Applied
Example 14 Base sheet 2 Sn-plated steel sheet Applied
Example 15 Base sheet 2 Sn-plated steel sheet Applied
Example 16 Base sheet 3 Ni-plated steel sheet
Example 17 Base sheet 3 Ni-plated steel sheet
Example 18 Base sheet 3 Ni-plated steel sheet
Example 19 Base sheet 5 Ni (diffused) plated steel sheet
26 / 39
[0058]
[Table 2B]
Base sheet Type of base sheet
Electric heating
+
Hot water cooling
Example 20 Base sheet 5 Ni (diffused) plated steel sheet
Example 21 Base sheet 7 Fe-Ni alloy plated steel sheet
Example 22 Base sheet 7 Fe-Ni alloy plated steel sheet
Example 23 Base sheet 4 Ni + Sn plated steel sheet Applied
Example 24 Base sheet 4 Ni + Sn plated steel sheet Applied
Example 25 Base sheet 6 Ni (diffuse) + Sn plated steel sheet Applied
Example 26 Base sheet 6 Ni (diffuse) + Sn plated steel sheet
Example 27 Base sheet 8 Fe-Ni alloy + Sn plated steel sheet Applied
Example 28 Base sheet 8 Fe-Ni alloy + So plated steel sheet Applied
Example 29 Base sheet 9 Ni-Sn alloy plated steel sheet
Comp. Example 1 Base sheet 2 Sn-plated steel sheet Applied
Comp. Example 2 Base sheet 4 Ni + Sn plated steel sheet
Comp. Example 3 Base sheet 1 Steel sheet
Comp. Example 4 Base sheet 3 Ni plated steel sheet
Comp. Example 5 Base sheet 5 Ni (diffused) plated steel sheet
Comp. Example 6 Base sheet 6 Ni (diffused) -F Sn plated steel sheet Applied
Comp. Example 7 Base sheet 8 Fe-Ni alloy + Sn plated steel sheet
Comp. Example 8 Base sheet 3 Ni-plated steel sheet
27 / 39
[0059]
1QVYY JA
Conditions for treatment of composite film
Electrolysis process Components of treatment solution
Process
duration
Electric
current
density
Zr ion
Nitric
acid ion
Ammonium
ion
Phosphoric
acid
Phenolic
resin
F ion lion Fe ion Ni ion
Water
cleaninB
treatment
(Sec) (A/dm2) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppin) (ppm)
Example 1 12.9 40.0 4900 17900 20000 (a)
Example 2 10.4 16.0 14700 5500 7700 33600 78 18370 (a)
Example 3 3.2 45.0 15500 7300 15900 26800 24490 (a)
Example 4 74 9.0 13100 10000 13800 40400 9370 2000 (a)
Example 5 13. 9 31.0 18700 13400 10900 - 1050 (a)
Example 6 14.9 16.0 6500 17000 5300 45500 380 (a)
Example? 19.6 2:0 18200_. 11500 13800 - 990 10200 20920 (a)
Example 8 4.4 8.0 1900 14600 19400 4600 1500 23700 6140 20390 (a)
Example 9 12.8 9.0 2100 4400 6600 - 150 (a)
Example 10 3.7 42.0 5400 10400 6200 - 640 45 (a)
Example 11 8.9 43. 0 11600 19600 13000 34700 1270 (a)
Example 12 13.2 46.0 8700 10300 2900 980 (a)
Example 13 15.4 25.0 300 10100 19500 30300 590 (a)
Example 14 0.9 50.0 10400 13200 10400 4800 700 3050 (a)
Example 15 13.3 31,0 6900 19200 11100 15200 1660 26000 350 420 (a)
Example 16 11.0 23.0 8900 8000 7200 350 (a)
Example 17 18.8 19.0 13800 4900 17100 940 (a)
Example 18 8.2 42.0 8600 4300 5100 33300 24 279 (a)
Example 19 12 6 4.0 11600 10700 7600 410 (a)
28 / 39
[0060]
Conditions for treatment of composite film
Electrolysis process Components of treatment solution
Process
duration
Electric
current
density
Zr ion
Nitric
acid ion
Ammonium
ion
Phosphoric
acid
Phenolic
resin
F ion Sn ion Fe ion Ni ion
Water
cleaning
treatment
(Sec) (A/dm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm) (ppm)
Example 20 15.9 37.0 15700 j 19000 4200 16600 190 (a)
Example 21 0.8 30.0 11100 9300 6100 5300 210 650 (a)
Example 22 8.5 19.0 18500 12300 6300 20800 230 27300 3410 22540 (a)
Example 23 17.3 30.0 11600 6700 17900 162 590 (a)
Example 24 0.7 38A -9400 2400 18200 720 96 (a)
Example 25 14.3 16.0 3700 8000 10300 27400 1942 140 (a)
Example 26 6.6 49.0 9800 13100 2000 193 720 (a)
Example 27 19.5 42.0 9000 1300 15000 35000 89 150 510 (a)
Example 28 8.6 37.0 4200 19400 1300 26600 1370 630 960 (a)
Example 29 10 5.0 11900 12900 20000 48900 1570 3200 204 160 (a)
Comp.Example 1 14.8 43.0 13600 18400 13500 710 (a)
Comp.Example 2 11.4 38.0 15400 19800 1700 83 17190 (a)
Comp.Example 3 8.0 6.0 2700 900 9000 8 (a)
Comp.Example 4 4.2 4. 0 2500 5400 1700 41300 7 8 (a)
Comp.Example 5 6.5 7.0 4400 7500 2400 17400 760 9830 (a)
Comp.Example 6 13.2 36.0 16900 7900 17200 19500 12220 570 (a)
Comp.Example 7 18.5 410 3600 9200 800 11200 24490 (b)
Comp.Example 8
-
3.5
-
47.0
----------
15000 J 70300 6700 11670 21560 (b)
29/39
[0061]
[Table 4A]
Attached amount
Amount of Zr
attached
Amount of P
attached
Amount of C
attached
Amount of F
attached
Amount of Sn
attached
Amount of Fe
attached
Amount of Ni
attached
(mg/m2) (mg/m2) (mg/m) (mg/m2) (mg/m2) (mg/m2) (mg/m2)
Example 1 68.0 19.3
Example 2 21.8 28.4 26 1261
Example 3 61.9 24.5 17.2
Example 4 20.1 11.5 6.3 1127
Example 5 58.8 560
Example 6 35.4 40.8 4.9
Example 7 99.8 23.0 0.07 1391
Example 8 40.2 0.2 37.9 0.09 15.0 142
Example 9 48.3 12.1
Example 10 1.9 0.9 9
Example 11 13.2 1.0 19.1
Example 12 61.2 8.0
Example 13 6.6 9.8 2.3
Example 14 16.2 4.3 0.2 17.6
Example 15 24.6 11.2 12.5 0.08 5.3 1504
Example 16 0.3 1925
Example 17 63.4 51
Example 18 33.3 6.6 11 126
Example 19 1.4 751
30 / 39
[0062]
[Table
Attached amount
Amount of Zr
attached
Amount of P
attached
Amount of C
attached
Amount of F
attached
Amount of Sn
attached
Amount of Fe
attached
Amount of Ni
attached
(mg/m) (mg/m2) (mg/m2) (mWm2) (mg/m2) (mg/ln) (mg/m2)
Example 20 6 .6 3.6 612
Example 21 8.9 3.9 8.2 1601
Example 22 41.4 30.8 27.1 0.09 17.4 1864
Example 23 73.3 17.5 7.6
Example 24 651) 3.1 3
Example 25 7.5 2.4 16.1 7
Example 26 60.1 11.6 15.9
Example 27 1.7 32.2 10.2 140 19.3
Example 28 90.2 40. 1 1.8 6.5 5
Example 29 46.7 18. 1 6.6 0.09 6.9 19
Comp.Example 1 115.0 10.5
Comp.Example 2 0.06 17.4 1886
Comp. Example 3 55.6 0.2
Comp.Example 4 85.7 17.5 3 2
Comp. Example 5 81.8 56.0 58.0 11.1
Comp.Example 6 30.3 7.4 10.7 1789
Comp.Example 7 84.9 0.30 15.8
Comp.Example 8 43.2 9.5 1148
31 / 39
[0063]
[Table 5A
Evaluation
Can-making
workability
Weldability
Film
adhesive
property
Primary-paint
adhesive
property
Secondary-paint
adhesive
property
Resistance
to
corrosion
under a
coated film
Non-lacquering
corrosion
resistance
Sulphide
staining
resistance
After-retort
rust
resistance
Wettability
Example 1 B B B A B B A A B A
Example 2 A-B A A-B A A-B A-B - A A-B A
Example 3 A-B A A-B A A-B A-B A A A-B A
Example 4 A-B A A-B A A-B A-B A A A-B A
Example 5 A-B A A-B A A-B A-B - A A-B A
Example 6 A A A A A A A A A A
Example 7 A A A A A A - A A A
Example 8 A A A A A A A A A A
Example 9. B A B A B B A A B A
Example 10 B A B A B A-B B A B Ail
Example 11 A-B A A-B A A-B A-B A A A-B Ai
Example 12 A-B A A-B A A-B A-B A A A-B A
Example 13 A A A A
i
A A A A A A
Example 14 A A A A A A A A A A
Example 15 A A A A A A A A A A
Example 16 B A B B B B - A B A
Example 1.7 B B B A B A-B - A B A
Example 18 A-B A A-B A A-B A-B - A A-B A
Example 19 A-B A A-B A A-B A-B - A A-B A
32 / 39
[0064]
Evaluation
Can-mak'
makinng
workability
Weldability
Film
adhesive
property
Primary-paint
adhesive
property
Secondary-paint
adhesive
property
Resistance
to
corrosion
under a
coated film
Non-lacquering
corrosion
resistance
Sulphide
staining
resistance
After-retort
rust
resistance
Wettability
Example 20 A A A A A A - A A A
Example 21 A A A A A A - A A A
Example 22 A A A A A A A A A A
Example 23 A A A A A A A A A A
Example 24 A A A A A A-B A A A A
Example25 A-B A A-B A A-B A-B A A A-B A
Example 26 A-B A A-B A A-B A-B A A A-B A
Example 27 A A A A A A A ,. A A A
Example 28 A A A A A A A A A A
Example 29 A A A A A A A A A A
Comp.Example 1 C D A A A A C- D A A A
Comp.Exan^ple 2 D A D, D D D A D B C
Comp.Example 3 D D D D D C B B A
Comp.Example 4 C-D C-D C-D C-D C-D C-D - A A A
Comp.Example 5 D D C-D C-D C-D B C B B A
Comp.Example 6 A D A A A A A A A A
Comp.Example 7 A A A A A D A A D D
Comp.Example 8 A A A A A A A A A D
33 / 39
[0065]
It can be found that Examples 1 to 29 according to the present invention
exhibited excellent can-making workability, weldability , film adhesive properties,
primary-paint adhesive properties , secondary-paint adhesive properties, resistance to
corrosion under a coated film, non-lacquering corrosion resistance, sulphide staining
resistance, after-retort rust resistance, and wettability. On the other hand, it was found
that Comparative Examples 1 to 8, which do not satisfy part of the requirements of the
present invention, were inferior in at least one of the can-making workability, the
weldability, the film adhesive properties , the primary-paint adhesive properties, the
secondary-paint adhesive properties , the resistance to corrosion under a coated film, the
non-lacquering corrosion resistance, the sulphide staining resistance, the after-retort rust
resistance, and the wettability deteriorated.
These are detailed descriptions of preferred embodiments according to the
present invention . However, the present invention is not limited the above-described
examples. It is obvious that a person who has ordinary knowledge in a technical field
to which the present invention belongs is able to reach various modification examples or
adjustment examples within the technical scope set forth in claims, and it should be
understood that these modification examples and adjustment examples naturally belong
to the technical scope of the present invention.
Industrial Applicability
[0066]
The steel sheet for a container according to the present invention exhibits
excellent can -making workability, weldability, film adhesive properties, primary-paint
adhesive properties, secondary-paint adhesive properties , resistance to corrosion under a
coated film, non-lacquering corrosion resistance , sulphide staining resistance,
after-retort rust resistance , and wettability, and in particular, is useful as a steel sheet for
a laminate-filmed container.
Reference Signs List
[0067]
A Cold-rolled steel sheet
34 / 39
B Plating
C Compositt film
S Steel sheet for a container
1-9 Base sheet
35/39
CLAIMS
1. A steel sheet for a container, the steel sheet comprising
a cold-rolled steel sheet, and
a composite film formed on the cold-rolled steel sheet through an electrolysis
process in a solution containing:
at least one metal ion selected from the group consisting of an Sn ion,,
an Fe ion, and an Ni ion;
a Zr ion;
a nitric acid ion; and
an ammonium ion, wherein
the composite film contains at least one element selected from the group
consisting of.
Zr of 0.1 to 100 mg/m2 in equivalent units of metal Zr:
Sri of 0.3 to 20 g/m2 in equivalent units of metal Sn;
Fe of 5 to 2000 mg/m2 in equivalent units of metal Fe; and
Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
2. The steel sheet for a container according to claim 1, wherein
the solution further contains at least one of a phosphoric acid ion and a
phenolic resin, and
the composite film further contains at least one of a phosphoric acid compound
of 0.1 to 50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50 mg/m2 in
equivalent units of C.
3. The steel sheet for a container according to claim 2, wherein
the solution further contains a fluorine ion, and
the composite film further contains a fluorine compound of not more than 0.1
mg/m2 in equivalent units of F.
The steel sheet for a container according to any one of claims 1 to 3, wherein
36 / 39
the cold-rolled steel sheet has at least one side surface including at least one of
an Sn-plated layer containing Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn, and
an Ni-plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
5. The steel sheet for a container according to claim 4, wherein
the at least one side surface of the cold-rolled steel sheet has the Sn-plated layer,
and
at least part of the Sn-plated layer is alloyed with the cold-rolled steel sheet
through a tin-reflow treatment.
The steel sheet for a container according to claim 4, wherein
the at least one side surface of the cold-rolled steel sheet has the Sn-plated layer,
and
there is provided, below the Sn-plated layer, an Ni-plated layer, an Fe-Ni alloy
plated layer, or an Ni-diffusion plated layer obtained through a thermal treatment after
Ni plating.
7. The steel sheet for a container according to claim 6, wherein
the at least one side surface of the cold-rolled steel sheet has the Sn-plated layer,
and
all or part of the Sn-plated layer is alloyed with the cold-rolled steel sheet
through a tin-reflow treatment.
8. A method of manufacturing a steel sheet for a container, including:
applying an electrolysis process to a cold-rolled steel sheet in a solution
containing:
at least one metal ion of an Sn ion, an Fe ion, and an Ni ion;
a Zr ion;
a nitric acid ion, and
an ammonium ion, to precipitate on the cold-rolled steel sheet, and
forming a composite film containing at least one element of:
Zr of 0.1 to 100 mg/r2 in equivalent units of metal Zr;
37 / 39
Sn of 0.3 to 20 g/m2 in equivalent units of metal Sn;
Fe of 5 to 2000 mg/m2 in equivalent units of metal Fe; and
Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
9. The method of manufacturing a steel sheet for a container according to claim 8,
wherein
the cold-rolled steel sheet has at'least one side surface including,at least one of
an Sn-plated layer containing Sn of 0.3 to 20 g/m2 equivalent units of metal Sn, and
an Ni plated layer containing Ni of 5 to 2000 mg/m2 in equivalent units of metal Ni.
10.. The method of manufacturing a steel sheet for a container according to claim 8,
wherein
the solution further contains at least one of a phosphoric acid ion and a
phenolic resin,"' and
the composite film further contains at least one of a phosphoric acid compound
of 0.1 to 50 mg/m2 in equivalent units of P, and a phenolic resin of 0.1 to 50 mg/m2 in
equivalent units of C.
11. The method of manufacturing a steel sheet for a container according to any one
of claims 8 to 10, further including
after the composite film is formed on the cold-rolled steel sheet, applying a
cleaning process of an immersion-process or spray process with hot water at not less
than 40°C for not less than 0.5 second.