Document Type] Specification
I
[Title of the Invention] CHEMICAL TREATMENT STEEL SHEET, AND METHOD
FOR PRODUCING CHEMICAL TREATMENT STEEL SHEET
[Technical Field]
5 [OOOl]
The present invention relates to a chemical treatment steel sheet, and a method
for producing a chemical treatment steel sheet.
[Background Art]
[OOO2]
10 There is mctal corrosion as one of variations with the lapse of time in metal in
use. In the related art, various techllologies have been suggested so as to prevent
corrosion from occurring in a metal. Examples of the technologies which are suggested
include a technology of performing plating with respect to a metal sheet, and a
technology of performing various surface treatments with respect to a surface of a metal
15 sheet or plating.
LOO031
Here, plated steel sheets having a so-called barrier-type plating layer lormed
thereon, sl-ch as a Ni-plated steel sheet, a Sn-pl&d steel sheet, and a Sn-based
alloy-plated steel sheet, are used to manufacture a inetal container that is intended to
20 preserve drinks or food. In a case of using these plated steel sheets as a steel sheet for
metal containers (steel sheet for containers) that is intended to preserve drinks or food, a
mst proof treatment wit11 chromate using hexavalent chromium or the like is performed
so as to secure adhesion between the steel sheet and a coating or a film, and corrosion
resistance in inany cases.
25 [O004]
2
However, the hexavalent chroiniurn that is used in the chromate treatment is
harinful in an environ~nentaal spect, and thus a chemical treatment film such as a
Zr-phosphorous iilni has been developed as a substitute for the chromate treatment that is
performed for the steel sheet for containers in the related art. For example, the
5 following Patent Document 1 discloses a steel sheet for containers having a chemical
treatment film that contains Zr, phosphoric acid, a phenol resin, and the like.
[Related Art Document]
[Patent Document]
[0005]
10 [Patent Document 11 Japanese Unexamined Patent Application, First
Publication No. 2007-284789
[Summary of the Invention]
[Problems to be Solved by the Invention]
[0006]
15 Here, in a case of using a Sn-plated steel sheet using the chemical treatment film
disclosed in Patent Document 1 as a steel sheet for containers intended to store acidic
contents such as acidic fruit, ihe steel sheet for containers is used without coating in order
. . . .
to prevent the contents from being ox~dizedb y reaction between eluted Sn and ox& m
the contents. However, from a result of exanlination by the present inventors, tlie
20 inventors have obtained the following finding: since the chemical treatment film turns
yellow (yellowing) in accordance with a variation with the passage of time, there is a
problem in that the exterior appearance deteriorates.
[0007]
The invention has been made in consideration of the above-described problems,
25 and an object thereof is to provide a chemical treatnleiit steel sheet in which yellowing in
3
accordance with a variation with the passage of time is prevented and satisfactory
exterior appearance can be maintained, and a method for producing the chemical
treatment steel sheet.
[Means for Solving the Problen~]
5 [OOOS]
From a result of intensive examination by the inventors for solving the
above-described problems, the inventors have found that all of the above-described
problems can be solved by using a Zr-phosphorous film as a chemical treatment film
layer to be formed on a barrier-type plating layer and by setting the amount of the
10 Zr-phosphorous film to be adhered in a specific range, and completed the invention.
The gist of the invention is as follows.
[0009]
(1) A chemical treatment steel sheet including: a steel sheet; a plating layer
which is provided on the steel sheet and contains 0.1 to 15 g/m2 of Sn in terms of the
15 amount of metal Sn, and in which a Sn layer is formed on a Fe-Sn alloy layer fornled by
alloying a part of or all of Sn through a tin melting treatment; and a chemical treatment
film layer which is formed on the plating layer and contains at least 0.01 to 3 mg/m2 of
Zr in terms of an amolmt of mela! Z.r and 0.01 to 5 mglm 2 of pl~osphor~in~ tse rms of a.n
amount of P.
20 (2) The cheillical treatment steel sheet according to (I), in which in the chemical
treatment film layer, the content of the Zr is 2.7 mg/m2 or less in terms of the a~nounot f
metal Zr.
(3) The chemical treatment steel sheet according to (1) or (2), in which in the
chemical treatment film layer, the content of the Zr is less than 1 mg/m2 in terms of the
25 amount of metal Zr.
4
(4) The cheinicai treatment steel sheet according to any one of (I) to (3), in
which in the chemical treatment film layer, the content of the Zr is 0.05 mglm2 or greater
in tem~osf the amount of metal Zr.
(5) The chemical treatment steel sheet according to any one of (1) to (4), in
5 which in the chemical treatment film layer, the content of the phosphorus is 4 mgim2 or
less in terms of the amount of P.
(6) The chemical treatment steel sheet according to any one of (1) to (5), in
which in the chemical treatment film layer, the content of the phosphorus is less than 1
mg/m2 in terms of the amount of P.
10 (7) The chemical treatment steel sheet according to any one of (1) to (6), in
which in the chemical treatment film layer, the content of the phosphorus is 0.03 mgim2
or greater in terms of the amount of P.
(8) The chemical treatment steel sheet according to any one of (1) to (7), in
which a YI value A of the chemical treatment steel sheet after storage for four weelcs
15 under an environment of a temperature of 40°C and a humidity of 80% and a YI value B
of the chemical treatment steel sheet before storage satisfy a relationship: A-B 54.
(9) The chemical treatment steel sheet according to any one of (1) to (8), in
-w-h~ic h in the plating layer, the anmuit of riieid Sn is 0.5 to 13 g'iii2.
(10) The chemical treatment steel sheet according to any one of (1) to (9), which
20 is used without performing a coating treatment on the chemical treatment film layer.
(1 1) Amethod for producing a chemical treatment steel sheet, including: treating
a plated steel sheet having a plating layer, which contains 0.1 to 15 of Sn in terms of
the amount of metal Sn and in which a Sn layer is formed on a Fe-Sn alloy layer formed
by alloying a part of or all of Sn through a tin melting treatment, on a steel sheet in a
5
chemical treatment bath containing 10 to 20000 ppm of Zr ions, 10 to 20000 ppm of
fluoride ions, 10 to 3000 ppm of phosphate ions, and 100 to 30000 ppm olnitrate ions
andlor sulfate ions to form a chemical treatment film layer on the plating layer, in which
a temperature ofthe chemical treatment bath is equal to or higher than 5°C and lower
5 than 90°C, and the treatment which is performed on the plated steel sheet is an electric
field treatment which is performed for 0.05 to 10 seconds using a cuilent of 0.5 to 20
I .Wdm2 or ail immersion treatment which is performed for 0.2 to 100 seconds
(1 2) The method for producing a chemical treatment steel sheet according to
(1 I), in which the content of the Zr ions in the chemical treatment bath is 100 to 17000
10 ppm, the content of the fluoride ions in the chemical treatment bath is 100 to 17000 ppm,
tlie content of the phosphate ions in the cheinical treatment bath is 20 to 2000 ppn~a, nd
the content of the nitrate ions ai~diors ulfate ions ill the chemical treat~nenbt ath is 1000 to
20000 ppm.
[Effect of the Invention]
15 [OOl 01
As described above, according to the invention, it is possiblc to prevent
yellowing in accordance with a variation with the passage of time in a steel sheet for
Zr-phosphorous film to be adhered and provided as a chemical treatment film layer in a
20 specific range.
[Brief Description of the Drawings]
[OOll]
[Figure lh] FIG. 1A is a view schematically showing a layer structure of a
chemical treatment steel sheet according to an embodiment ofthe invei-ition.
6
[Figure 1 B] FIG 113 is a view schematically showing a layer structure of the
chemical treatment steel sheet according to the embodiment.
[Figure 21 FIG. 2 is a view schematically showing an example ofthe chemical
treatment steel sheet according to the embodiment.
[Figure 31 FIG. 3 is a flowchafi showing an example of a flow of a method for
producing the chemical treatment steel sheet according to the embodiment.
[Figure 41 FIG. 4 is a graph for illustrating Test Example 1.
[Embodiment of the Invention]
[0012]
Hereinafter, a preferred embodiment of the invention will be described in detail
with reference to the accompanying drawings. Furthermore, in this specification and
drawings, the same reference numeral will be given to constituent elements having
substai~tiallyth e same configuration, and overlapping description thereof will be omitted.
[OOI 31

First, a configuration of a chemical treatment steel sheet according to an
embodiment of the invention will be described in detail with reference to FIG. 1A and
FIG 1R. FIG !A and FIG !R schematical!y show a !ayer structure of the chemical
treatment steel sheet according to this embodiment when seen from a lateral side.
[0014]
As shown in FIG. 1A and FIG. lB, a chemical treatment steel sheet 10 according
to this embodiment includes a plated steel sheet 101 and a chemical treatment film layer
107. Here, the plated steel sheet 101 has a steel sheet 103 as a base material and a
plating layer 105 formed on the steel sheet 103. The plating layer 105 and the chemical
treatment film layer 107 may be formed on only one surface of the steel sheet 103 as
shown in FIG. IA, or may he fonned on both surfaces of the steel sheet 103 opposed to
each other as shown in FIG. 1B.
[0015]
[With Respect to Steel Sheet I031
5 The steel sheet 103 is used as a base material of the chemical treatment steel
sheet 10 according to this embodiment. The steel sheet 103 that is used in this
embodiment is not particularly limited, and in general, a known steel sheet that is used as
a steel sheet for containers can be used. A method for producing the known steel sheet
and a material thereof are also not particularly limited, and a steel sheet which is
10 produced through from a typical billet producing process to a known process such as
hot-rolling, pickling, cold-rolling, annealing, and temper rolling may be used.
[00 161
[With Respect to Plating Layer 1051
The barrier-type plating layer 105 containing at least Sn is for~nedo n a surface
15 of the steel sheet 103. Here, the barrier-type plating layer is a plating layer that
suppresses corrosion of the steel sheet 103 by forming a metal film of Sn on the surface
of the steel sheet 103 by using Sn that is a more electrochemically noble metal in
. .
complrison to Fe tha? constitl~testh e steel sheet I03 that is a base mzteria! In order for a
corrosion factor not to act on the base material.
20 [00 171
Hereinafter, an example of the plating layer 105 according to this embodiment
will be described in detail with reference to FIG. 2. For thc sake of convenience, FIG. 2
shows a case where the plating layer 105 and the chemical treatment film layer 107 are
formed on only one surface of the stcel sheet 103. However, it is indisputable that the
25 plating layer 105 and the cheinicai ireatment film layer 107 may be formed on both
8
surfaces of the steel sheet 103 opposed to each other
[0018]
This plating layer 105 includes a Fe-Sn alloy layer 105a which is formed on at
least one surface of the steel sheet 103 and formed of a Fe-Sn alloy, and a Sn plating
5 layer 105b which is fonned on the Fe-Sn alloy layer 105a. Here, the Fe-Sn alloy layer
105a is formed by alloying a part of the Sn plating layer 105b with Fe of the steel sheet
103 through a tin melting treatment (reflow treatment) to be described later.
[0019]
In this specification, "Sn plating" includes not only plating with metal Sn, but
10 also metal Sn including impurities and metal Sn including a small amount of eleinents
added thereto. The Sn plating method is not particularly limited, and for exan~plea,
known electroplating method is preferably used. A method for plating by in~n~ersina g
steel sheet in molten Sn or the like may also be used.
[0020]
15 The plating layer 105 provided by the Sn plating is formed to secure corrosion
resistance and weldability. Since Sn itself has high corrosion resistance, it exhibits
excellent corrosion resistance and weldability as metal Sn or a Sn alloy formed through a
tin me!ting treatnxnt to be described !ater.
[0021]
20 In the whole plating layer 105 including the Fe-Sn alloy layer 105a and the Sn
plating layer 105b provided as described above, Sn is contained in a range of 0.1 to 15
g/m2 in terms of the amount of metal Sn.
LO0221
Sn has excellent workability, weldability, and coi~osionre sistance. When the
25 tin melting treailnent is performed after Sn plating, it is possible to further improve the
9
corrosion resistance and surface exterior appearance (mirror surface cxtcrior appearance).
In order to obtain such effects, 0.1 g/m2 of Sn is required to be contained in terms of the
amount of metal Sn in the whole plating layer 105. In addition, the greater the amount
of metal $11, the furlher the corrosion resistai~ceis in~proved. However, when the
5 amount of metal Sn is greater than 15 g/m2, the corrosion resistance improving effect is
saturated. Therefore, from the economic viewpoint, the amount of metal Sn is set to 15
g/m2 or less. The Sn content in the whole plating layer 105 is more preferably 0.5 to 13
g/m2 in terms of the amount of metal $11. When 0.5 g/m2 or greater of Sn is contained
in terms of the amount of metal Sn, it is possible to more reliably realize the effects. In
10 addition, when the amount of metal Sn is set to 13 g/m2 or less, the plating layer
production cost can be further reduced.
[0023]
For the tin melting treatment (reflow treatment) for fornling the Fe-Sn alloy
layer 105a, the Sn plating formed by performing Sn plating on the steel sheet 103 and by
15 then setting the temperature to 200°C or lower may be melted and then rapidly cooled
Through this tin melting treatment, Sn in the Sn plating positioned on the steel sheet 103
is alloyed with Fe in the steel sheet, and thus a Fe-Sn alloy is formed.
[!I024]
The thick ratio between the Fe-Sn alloy layer 105a and ihe Sn plating layer 105b
20 is not particularly limited. The amount to be adhered may be secured in the whole
plating layer 105 in terms of the amount of metal Sn.
100251
Hereinafter, a speciiic example of the plating layer 105 will be described with
reference to FIG. 2
25 I00261
10
The plating layer 105 is preferably fomled 011 both surfaces of the steel sheet
103 from the viewpoint of improvement in corrosion resistance and the like. However,
in a case where a surface treatment layer other than the plating layer 105 for improving
corrosion resistance and the like is formed on one surface of the steel sheet 103 from the
5 viewpoint of reduction of the production cost and the like, the plating layer 105 may be
formed at least on the other surface of the steel sheet 103. I11 a case where a chemical
treatment steel sheet in which the plating layer 105 is formed on only one surface of the
steel sheet 103 as described above is subjected to can malting, it is performed such that
for example, the surface on which the plating layer 105 is formed is on the inside of a
10 container.
[0027]
However, in a case of using the steel sheet, on which the plating layer 105 is
formed, as a steel sheet for containers which store acidic contents such as acidic fruits, a
coating treatment is not performed on a surface that comes into contact with the acidic
15 contents. This is because, when the plating layer 105 and the acidic coiltents come into
direct contact with each other, Sn in the plating layer 105 is eluted and preferentially
reacts with 0 2 in the contents, thereby preventing oxidation of the acidic contents.
EIo~vevert, in oxide (EnO), which is generated though a reaction between Sn in the
plating layer 105 and 01, is a yellow conlpound. Accordingly, the plated steel sheet
20 which comes into contact with the acidic contents tunls yellow with the passage of time.
The yellowing deteriorates the exterior appearance of the container using the plated steel
sheet, and does not give a favorable impression to consunlers of the contents.
Accordingly, the inventors have thought of a configuration in which a chemical treatment
film that contains Zr as described in Patent Document 1 is foinled on a plating layer in
25 order to suppress the yellowing of the surface of the plated steel sheet.
11
lo0281
However, it has been obvious that in a case where the chemical treatmeill film
that contains Zr as described in Patent Document 1 is formed on the plating layer 105 and
a variation of the chemical treatment film with thc passage of time is investigated, when
5 the amount of the chemical treatment film to be adhered that contains Zr is equal to or
greater than a predetermined amount, the chemical treatment film itself turns yellow in
accordance wit11 a variation wit11 the passage of time.
[0029]
Accordingly, the inventors have performed further examination, and completed a
10 technology of suppressing yellowing of a chemical treatment film itself that contains Zr
and of maintaining satisfactory exterior appearance.
[0030]
That is, in the invention, a Zr-containing chemical treatment film, of which an
amount to be adhered is in a specific range, is fonned on the plating layer 105.
15 [003 11
[With Respect to Chemical Treatment Film Layer 1071
As shown in FIGS. 1A to 2, the chemical treatment film layer 107 is formed on
the p!ating layer 105. The chemical treatment fi!m !ayer 107 is a co!nposi!e !!!!TI layer
that mainly contains a Zr compound, and contains 0.01 to 3 mg/i~o~f2 Z r in terms ofthe
20 amount of metal Zr and 0.01 to 5 mg/m2 of phosphorus in terms of the amount of P.
[0032]
In a case where the Zr component and the phosphorus component are
independently formed as a Zr film and a phosphate film, respectively, a certain degree of
effect is obtained on corrosion resistance or adhesion, but the effect is not sufiicient in
25 practical use. However, as is the case of the chemical treatment film layer 107
12
according to this ernbodin~entw, hen the chemical treatment film layer 107 is fonned as a
conlposite film in which a Zr component and a phosphorus component are combined, it
is possible to exhibit excellent practical performance.
[0033]
5 The Zr component contained in the chemical treatment film layer 107 according
to this embodiment has a function of improving corrosion resistance, adhesion, and
working adhesion. The Zr component according to this embodiment includes a plurality
oCZr compounds such as Zr oxide, Zr phosphate, Zr hydroxide, and Zr fluoride. The Zr
component is excellent in corrosion resistance and adhesion. Accordingly, the greater
10 the anlount of the Zr component contained in the chemical treatment film layer 107, the
further the corrosion resistance and the adhesion of the chemical treatment steel sheet 10
are improved. On the other hand, as described above, as the amount of the Zr
component increases, the yellowing occurs with the passage of time. Accordingly, in
the chemical treatment film layer 107 according to this embodiment, the content of the Zr
15 component is limited in a specific range in order to maintain the corrosion resistance,
adhesion, and working adhesion and realize yellowing resistance.
[0034]
Specifical!y, in a case where the content of the Zr component which is adhered
onto the plating layer 105 as the chemical treatment film layer 107 is 0.01 mg/m2 or
20 greater in terms of the amount of metal Zr, coil-osion resistance, adhesion of a coating
and the like, and yellowing resistance, which are suitable in practical use, are secured.
On the other hand, although corrosion resistance and adhesion of a coating and the like
are improved with an increase of the content of the Zr component, when the content of
the Zr component is greater than 3 ing/m2 in terms of the amount of metal Zr, yellowing
25 characteristics of the clie~nicatlr eatment film layer 107 in accordance with a variation
13
with the passage of time become significa~~tA. ccordingly, in the chemical treatment
steel sheet 10 according to this embodiment, the content of the Zr component (that is, Zr
content) is set to 0.01 mg/m2 to 3 mg/m2 in terms of the amount of metal Zr.
[0035]
5 Here, the content of the Zr component is preferably 2.7 mg/m2 or less in tem~sof
the amount of metal Zr, and more preferably less than 1 mg/m2 in terms of the amount of
metal Zr. In addition, the content of the Zr cornpollent is preferably 0.05 mg/m2 or
greater in terms of the amount of metal Zr. By setting the amount of metal Zr in the
above-described range, it is possible to more reliably achieve coexistence of the
10 corrosion resistance, adhesion of a coating and the like, and yellowing resistance.
[0036]
The chemical treatment film layer 107 further contains one or more kinds of
phosphate coinpounds in addition to the above-described Zr component.
[003 71
15 The phosphorus component according to this embodimeilt has a function of
improving corrosion resistance, adhesion, and working adhesion. The phosphorus
component according to this embodiment includes one kind of phosphate compound such
as Fe phosphate, Sn phosphate, and Zr phosphate which are formed through a rea.c,tion
with the base (steel sheet 103 and plating layer 105), the Zr component, or an aluminum
20 component to be described later, or a composite component including two or more kinds
of the phosphate compounds. The phosphate component is excellent in corrosion
resistance and adhesion. Accordingly, the greater the amount of the phosphate
component formed, the further the corrosion resistance and the adhesion of the chemical
treatment steel sheet 10 are improved
25 1003 81
14
Specifically, in a case where the content of the phosphorus cornpollent in the
chemical treatment film layer 107 is 0.01 ing/m2 or greater in terms of the anlount of P in
consideration of the Zr content in the above-described range, corrosion resistance,
adhesion of a coating and the like, and yellowing resistance, which are suitable in
5 practical use, are secured. On the other hand, although corrosion resistance and
adhesion of a coating and the like are iinproved with ail increase of the content of the
phosphorus component, when the content of the phosphorus co~nponentis greater than 5
mg/m2 in teims of the amount of P, yellowing characteristics of the chemical treatment
film layer 107 in accordance with a variation with the passage of time become significant
10 Accordingly, in the chemical treatment steel sheet 10 according to this embodiment, the
content of the phosphorus component is set to 0.01 mg/m2 to 5 mg/m2 in terms of the
amount of P.
100391
Here, the content of the phosphorus component is preferahly 4 mg/m2 or less in
15 terms of the amount of P,a nd more preferahly less tl~ail1 mg/m2 in terms of the amount
of P. In addition, the content of the phosphorus component is preferably 0.03 mg/in2 or
greater in terms of the amount of P. By setting the amount of P in the above-described
raEge, it is possible to more reliably achieve coexistence of the corrosion resistance,
adhesion of a coating and the like, and yellowing resistance.
20 [0040]
The chemical treatment film layer 107 containing the Zr component and the
phosphorus conlponent is formed through an electrolytic treatment (cathode electrolytic
treatment) or an immersion treatment. In order to form the chemical treatment film
layer 107 through the electrolytic treatment or the immersion treatment, it is necessary to
25 determine components in a chcmical treatment liquid in accordance with the kind of a
15
film to be formed as a chemical treatment film. Specilically, a chemical treatment
liquid containing 10 ppm to 20000 ppm of Zr ions, 10 ppm to 20000 ppln of fluoride ions
(F-), 10 ppm to 3000 ppm of phosphate ions, and 100 ppm to 30000 ppm of nitrate ions
and/or sulfate ions is used.
5 [0041]
The chen~icatlr eatment liquid preferably contains 100 ppm to 17000 ppln of Zr
ions, 100 ppm to 17000 ppm of fluoride ions, 20 ppm to 2000 ppm of phosphate ions,
and 1000 ppm to 20000 ppm of nitrate ions and/or sulfate ions. A decrease in the
amount of Zr to bc adhered can be more reliably prevented by setting the amount of Zr
10 ions to be added to 100 ppm or greater. In addition, white turbidity of the chemical
treatment film in accordance with precipitation of a phosphate can bc more reliably
prevented by setting the amount of fluoride ions to be added to 100 ppm or greater.
Similarly, white turbidity of the chemical treatment film in accordance with precipitation
of a phosphate can be more reliably prevented by setting the amount of phosphate ions to
15 be added to 20 ppm or greater. In addition, a decrease in adhesion efficiency of the
chemical treatment film can be more reliably prevented by setting the amount of nitrate
ions and/or sulfate ions to be added to 1000 ppm or greater. When the upper limits of
t!~e amoi.~nis of the respective components to be added are set to the above-desc,ribed
values, the production cost of the chemical treatment film layer 107 can be more securely
20 reduced.
[0042]
Here, it is not preferable that the amount of fluoride ions to be added is less than
100 ppm, because the amount of fluorine surrounding Zr ions as a complex decreases,
and thus Zr does not adhere. In addition, it is not preferable that the amount of fluoride
25 ions to be added is greater than 17000 ppm, because the amount of fluorine surrounding
I6
Zr ions as a complex increases, and thus Zr excessively adheres.
[0043]
It is not preferable ihat the amount of nitrate ions to be added is less than 1000
ppm, because the amount of nitric acid that increases the adhesion eff~cieilcyo f Zr ions
5 decreases, and thus Zr does not adhere. In addition, it is not preferable that the amouilt
of nitrate ions to be added is greater than 20000 ppm, because the amount of nitric acid
that increases the adhesion efficiency of Zr ions increases, and thus Zr excessively
adheres.
[0044]
10 It is not preferable that the amount of sulfate ions to be added is less than 1000
ppm, because the amount of sulfuric acid that increases the adhesion efficiency of Zr ions
decreases, and thus Zr does not adhere. In addition, it is not preferable that the amount
of sulfate ions to be added is greater than 20000 ppm, because the amount of sulfuric acid
that increases the adhesion efficiency of Zr ions increases, and thus Zr excessively
15 adheres.
[0045]
If necessary, a phenolic resin and the like may be further added to the chemical
. . treatme!?l !iqu.!d.
[0046]
20 The pH of the chemical treatment liquid is preferably in a range of 3.1 to 3.7,
and more preferably about 3.5. If necessary, nitric acid, ammonia, or the like may be
added to adjust the pH.
[0047]
The temperature of the chemical treatment liquid is equal to or higher than 5°C
17
and lower than 90°C. It is not preferable that the temperature of the chemical treatment
liquid is lower than 5"C, because the film formation efficiency is poor, and is not
economically efficient. In addition, it is not preferable that the temperature of the
chemical treatment liquid is 90°C or higher, because the structure of a film that is formed
5 is not uniform, defects, breaking, microcracks, and the like occur, and thus it becomes
difficult to form a dense film and the defects and the like become the origin of corrosio~~
and the like.
[0048]
In a case where the chemical treatment film layer 107 is formed using the
10 chemical treatment liquid through an electrolytic treatment (cathode electrolytic
treatment), the electrolytic treatment is performed at a current density of 0.5 ~ l d m ' to 20
.4/dm2 for an electrolytic treatment time of 0.05 seconds to 10 seconds. It is not
preferable that the current density is lower than 0.5 ~ l d m lb,e cause the amount of the
cltemical treatment film layer to be adhered decreases, and productivity is reduced since
15 a long electrolytic treatment time may be required. In addition, it is not preferable that
the current density is higher than 20 A/dm2, because the amount of the chemical
treatment film layer to be adhered is greater than a predetermined amount and saturated,
and thus in some cases, a fiim which is not sufficientiy adhcred washes off (peeis offj
during a washing process by water washing or the like after the electrolytic chemical
20 treatment. Thus, tics case is not economically efficient. It is not preferable that the
electrolytic treatment time is shorter than 0.05 seconds, because the amount ofthe film to
be adhered decreases, and thus corrosion resistance, adhesion of a coating, and the like
inay decrease. In addition, it is not preferable that the electrolytic treatment time is
longer than 10 seconds, because the amount of the film to be adhered is greater than a
18
predetermined amount and saturated, and thus in some cases, a Glin which is not
sufficiently adhered washes off (peels off) during the washing process by water washing
or the like after the electrolytic chemical treatment. Thus, this case is not econoinically
efficient.
5 [0049]
By performing the electrolytic treatment at the above-described electrolytic
current density for the above-described energization time, it is possible to form an
appropriate amount of a film on the surface of the steel sheet.
[0050]
10 As described above, the chemical treatment film layer 107 according to this
embodiment contains a small amount of the Zr component and the phosphorus
component. Accordingly, the chemical treatment film layer 107 according to this
embodiment can also be formed through an immersion treatment other than the
above-described electrolytic treatment.
15 [0051]
In a case where the chemical treatment film layer 107 is formed using the
chemical treatment liquid through an immersion treatment, the immersion time for
immersing the plated steel sheet in the chemical treatment lin,~idis ret to 0.2 to 100
seconds. It is not preferable that the immersion time is shorter than 0.2 seconds,
20 because the amount of the chemical treatment film layer to be adhered decreases, and
productivity is reduced since a long immersion treatment time may be required. In
addition, it is not preferable that the immersion time is longer than 100 seconds, because
the amount of the chemical treatment film layer to be adhered is greater than a
predetermined amount and saturated, and thus in some cases, a film which is not
25 suficicntly adhered washes off (peels off) during a washing process by water washing or
19
the like after the immersion treatment. Tlius, this case is not economically efficient.
[0052]
In the formation of the chemical treatment film layer according to this
embodiment, tannic acid may be further added to an acidic solution to be used in the
5 treatment. When i11e tannic acid is added to the acidic solution, the tannic acid reacts
with iron (Fe) in the steel sheet during the treatment, and a film of tannic acid Fe is
fonned on the surface of the steel sheet. The fill11 of tannic acid Fe improves rust
resistance and adhesion. Accordingly, if necessary, the chemical treatment film layer
may be formed in the acidic solution containing tannic acid added thereto.
10 [0053]
As a solvent of the chemical treatment liquid which is used in the formation of
the chemical treatment fihn according to this embodiment, for example, deionized water,
distilled water, or the like can be used. In a case where the chemical treatment film is
formed through an electrolytic treatment, electric conductivity of the solvent is preferably
15 considered, and it is preferably 10 pS/cm or less, more preferably 5 pS/cm or less, and
still more preferably 3 pS/cm or less. However, the solvent of the chemical treatment
liquid is not limited thereto, and can be appropriately selected in accordance with a
--,.A 2 - 1 A- LA A:""-?-.-> ula~ellaLU~ VC: UA:I"~"-~?V-.-I>Y CU, a clu--l-l lidt:io n method, foiination conditioiis of the chemical
treatment film, and the like. However, it is preferable to use deionized water or distilled
20 water from aspects of industrial productivity based on stability in the amount of each
conlponent to be adhered, cost, and environment.
[0054]
For example, a Zr complex such as HzZrF6 can be used as a supply source of Zr
in the chemical treatment liquid which is uscd in the foimation of the chemical treatment
20
film layer 107 according to this embodiment. Zr in the Zr complex exists as zr4+ in the
chemical solution through a hydrolysis reaction. The Zr ions further rapidly react in the
cheinical treatment liquid and form a compound such as ZrOl and Zr3(P04)4, whereby a
Zr film can be formed through a dehydration and condensatioil reaction with a hydroxyl
5 group (-OH) that exists on a metal surface.
loo551
When a phenolic resin is added to the chemical treatment liquid, the phenolic
resin may be amino alcohol modified to be water-soluble.
[0056]
10 The above-described chemical treatment steel sheet 10 according to this
embodiment exhibits excellent yellowing resistance by setting the amount of the
chemical treatment film layer 107 to be adhered in the above-described range. For
example, the chemical treatment steel sheet 10 is stored for four weeks under an
environment of a temperature of 40 degrees and a humidity of 80%. In such a case, a
15 YI value (yellowness index) A of the chemical treatment steel sheet after storage and a YI
value B of the chemical treatment steel sheet before storage satisfy a relationship:
(A-B)54 (that is, a AYI value which is a difference in the YI value before and after
storage is 4 or less).
I00571
20 Here, the YI value (yellowness index) is a degree of departure of color from
colorless or white to yellow, and is displayed as a positive value. Accordingly, when
the Y1 value is displayed as a negative value, this case represents that the color turns blue.
As a method for measuring the YI value, the YI value is calculated by substituting
tristimulus values X, Y, and Z obtained by using a white measurement meter into the
25 following (Formula 100).
2 1
[OOSS]
YI Value=l00(1.28X-1.06Z)+Y . . .. (Fom~ula1 00)
[0059]
The YI value (j~ellownessin dex) is a value obtained by digitizing tristimulus
5 values (perceiving sensitivity of red, blue, and yellow which are sensed by eyes of human
beings) of a color. The higher the YI value on a positive side, the deeper the yellow
color. The higher the YI value on a negative side, the deeper the bluish white color.
[0060]
Accordingly, in a case where the AYI value is a positive value due to the storage
10 under the above-described environment, this case represents an increase in the
yellowness index, and in a casc where the AYI value is a negative value, this case
represents a decrease in the yellowness index and an increase in the degree of
bluish-whiteness.
[0061]
15 Here, in a case where the variation (A-B) in the YI value is greater than 4, cyes
of human beings perceive that ail object turns yellow. Accordingly, when the variation
in the YI value is 4 or less in the chemical treatment steel sheet 10 according to this
embodimenr, human beings do nor perceive yeiiowing ofrhe cheinicai ueannenr steei
sheet in accordance with a variation with the passage of time, and thus satisfactory
20 exterior appearance of the chernical treatment steel sheet I0 can be maintained.
[0062]

Here, the amount of metal Sn in the plating layer 105 can be measured tluough,
for exa~nplea, fluorescent X-ray inetllod. In this case, a calibration curve with respect
22
to the amount of metal Sn is specified in advance using a known sample for measurement
of the amount of metal Sn to be adhered, and the amount of metal Sn is relatively
specified by using the calibration curve that is created.
100631
5 The amount of metal Zr and the amount of P in the chemical treatment film layer
107 can be measured through, for example, a quantitative analysis method such as
fluorescent X-ray analysis. In addition, it is possible to specify existence of a
compound in the chemical treatment film layer 107 by performing analysis with X-ray
photoelectron spectroscopy (XPS).
10 [0064]
Furthermore, the method for measuring each component amount is not limited to
the above-described method, and other ltnown measurement methods can be applied
thereto.
[0065]
15
Measurement of the YI value (yellowness index) may be performed by using a
spectral calorimeter based on JIS 2-8722 condition c. With regard to a measurement
type, the meast1rernent can be performed ikrough SCT (including regy!ar reflection light)
ineasurement that is less susceptible lo an effect by a surface property. In addition, with
20 regard to measurement conditions, it is important to perform the measurement under
constailt conditions such as a constant light source, constant humidity; and a constant
temperature.
[0066]
Furthermore, in measurement of the YT value, for example, it is preferable to
25 measure YI values at a plurality of measurement points such as arbitrary 20 points per 1
23
m 2 , and to use an average value thereof. Here, the measurement points represent "a
plurality of arbitrary measurement points on one surface at the outermost surface portion
of the chemical treatment film". In addition, it is preferable that the measurement
points are set to points which are spaced away from each otllcr by at least 10 em
5 Specifically, in a case of a large sheet having dimensions of I mx 1 m, it is preferable that
measurement points are sampled, and points spaced away from each other by 10 cm or
more are sampled to perform the measurement.
[0067]
Ii[ereinafter, a c ~ ~ g u r a t ioofn th e chemical treatment steel sheet 10 according to
10 this embodiment will be described in detail with reference to FIGS. lA to 2.
[0068]

Next, a method for producing the chemical treatment steel sheet 10 according to
this embodiment will be described in detail with reference to FIG. 3. FIG. 3 is a
15 flowchart for illustrating an example of a flow of the method for producing the chemical
treatment steel sheet according to this embodiment.
[0069]
In the me!hod for producing the chemical ttreatmsn? steel sheet 10 acir,cordinacr +n --
this embodiment, first, a known prel~minarytr eatment is performed with respect to the
20 steel sheet 103 as necessary (Step S101).
[0070]
Then, the plating layer 105 is formed on a surface of the steel sheet 103 using
the above-described method (Step S103). Then, the chemical treatment film layer 107
is formed through a cathode electrolytic treatment or ail immersion treatment (Step
25 S105).
24
j00711
Then, a known post-treatment is perfomled as necessary with respect to the steel
sheet 103 on which the plating layer 105 and the chemical treatment film layer 107 are
formed (Step S107).
5 [0072]
Through the treatment performed in this flow, the chemical treatment steel sheet
10 according to this embodiment is produced.
[Examples]
[0073]
10 Hereinafter, the chemical treatment steel sheet and the method for producing the
chemical treatment steel sheet according to the elubodiment of the invention will be
described in detail with reference to Test Examples. 111 addition, the following Test
Examples are examples of the chemical treatment steel sheet and the method for
producing the chemical treatment steel sheet according to the embodiment of the
I 15 invention, and the chemical treatment steel sheet and the method for producing the
chemical treatment steel sheet according to the embodiment of the invention are not
limited to the followillg examples.
[0074]
(Test Example I)
20 I{ereinafter, first, verification was made as to how the YI value varies before and
after storage for 4 weeks under an environment of a temperature of 40°C and a humidity
of 80% while varying the amount of a Zr componeilt in the chemical treatment film layer
107. The component content and the YI value were measured by the above-described
method.
25 100751
25
In the following Test Example 1, using a steel sheet, which is typically used as a
steel sheet for containers, as a base material, a plating layer 105 was formed. The
amouilt of Sn to be adhered in tlie plating layer 105 is 2.8 g/m2. Furthermore, a
plurality of samples each having a chemical treatment film layer 107, in which the
5 contents of Zr components were different from each other, were produced by changing
the amount of Zr to be adhered in a chemical treatment liquid. Ilere, in each sample,
the amount of a phosphorus component to be adhered was 3.0 mg/n12 in terms of the
amount of P.
[0076]
10 Obtained results are shown in FIG. 4.
In FIG. 4, the horizontal axis represents tlie amount of a Zr component (the
amount of metal Zr) to be adhered in the chemical treatment film layer 107, and the
vertical axis represents a difference (A-B) in the YI value before and after storage. As
is clear from FIG. 4, it is found that in a case where the amount of Zr to be adhered is 0
15 mg/m2 in tenns of the amount of metal Zr, yellowing by SnO is recognized (difference in
YI value = 5), and in a case where the amount of metal Zr is 0.08 mg/m2, the difference
in the YI value is reduced up to 1.2 and yellowing resistance is realized. In addition, it
is found that in a case where the amount of Zr to be adhered is 2.7 mg/m2. the difference
in the YI value is about 3.5, and in a case where the amount of metal Zr to be adhered is
20 4 mg/m2, the difference in the YI value is greater than 4, and the difference in the YI
value increases in accordance with aii increase in the amount of Zr to be adhered.
[0077]
As is clear from the results, it is found that yellowing resistance of the produced
cheillical treatment steel sheet 10 is remarkably improved by setting the amount of a Zr
25 component to be adhered in the chemical treatment film layer 107 in a prcdeteimined
range.
[0078]
(Test Example 2)
Next, using a steel sheet, which is typically used as a steel sheet for containers,
5 as a base material, plating layers 105 in which the amount of metal Sn is as shown in
Table 1 was formed through the above-described method. Subsequently, using a
chemical treatment liquid having components shown in the following Table 1, a chemical
treatment film layer 107 was formed on the plating layer 105. The production
conditions when the chemical treatment fihn layer 107 was formed are as shown in the
10 following Table 1.
[0079]
With respect to respective samples which were produced a5 described above, YI
values before and after storage for 4 weeks under an environment of a temperature of
40°C and a humidity of 80% were iitvestigated. The component content and the YI
15 value were measured by the above-described method.
[OOSO]
[Table 11

28
[OOXl]
As is clear from the above Table 1, it is found that thc variation in the YI value
of the chemical treatment steel sheet having the plating layer 105 and the chemical
treatment film layer 107 according to the embodiment of the invention is 4 or less, and
5 yellowing resistance of the chemical treatment steel sheet is reinarlcably improved.
[0082]
Hereinbefore, preferred embodiments of the invention have been described in
detail with reference to the accompanying drawings, but the invention is not limited to
the example. It should be understood by those skilled in the art that various
10 modification examples and variations may be made in a scope ofthe technical sprit
described in claims, and these also pertain to the technical scope ofthe invention.
[Description of the Reference Symbols]
[0083]
10: CHEMICAL TREATMEN r STEEL SHEET
15 101: PLATED STEEL SHEET
103: STEEL SHEET
105: PLATING LAYER
107: CI-IEMICAL TREATMENT FILM LAYER
29
llDocunlent Type] Claims
[Claim 11
A chemical treatment steel sheet comprising:
a steel shect;
5 a plating layer which is provided on the steel sheet and contains 0.1 to 15 g/m2
I of Sn in temls of the amount of metal Sn, and in which a Sn layer is formed on a Fe-Sn
alloy layer formed by alloying a part of or all of Sn ihrough a tin melting treatment; and
a chemical treatment film layer which is formed on the plating layer and
contams at least 0.01 to 3 mg/n12 of Zr in terms of an amount of metal Zr and 0.01 to 5
10 mg/in2 of phosphorus in terms of an amount of P.
[Claim 21
The chemical treatment steel sheet according to claim 1,
wherein in the chemical treatment film layer, the content of the Zr is 2.7 mg/m2
or less in terms of the amount of metal Zr.
15 [Claim 31
The chemical treatment steel sheet according to claim 1 or 2,
whercin in the chemical treatment fill11 layer, the content ofthe Zr is less than 1
ing/m2 in terms of the amount of metal Zr.
[Claim 41
20 The che~nicatlr eatment steel shect according to any one of claims 1 to 3,
wherein in the chemical treatment film layer, the content of the Zr is 0.05 mg/m2
or greater in terms of the amount of metal Zr.
[Claim 51
The chemical treatment steel shcet according to any one of claims 1 to 4,
25 wherein in the chemical treatment film layer, the content of the phosphorus is 4
30
mg/m2 or less in terms of the amount of P.
[Claim 61
The clien~icatlr eatment steel sheet according to any one of claims 1 to 5,
wherein in the chemical treatment film layer, the content of the phosphorus is
5 less than 1 mg/m2 in terms of the amount of P.
[Claim 71
The cheinical treatment steel sheet according to any one of claiins 1 to 6,
wherein in the chemical treatment film layer, the content of the phosphorus is
0.03 ~ngliiol~r g reater in terms of the amount of P.
10 [Claim 81
The chemical treatment steel sheet according to any one of claims 1 to 7,
wherein a YI value A of the chemical treatment steel sheet after storage for four
weeks under an environment of a temperature of 40°C and a l~uii~idiotyf 80% and a YI
value B of the chenlical treatment steel sheet before storage satisfy a relationship: A-B 5
15 4.
[Claim 91
The chemical treatment steel sheet according to any one of claims 1 to 8,
wherein in the plating layer, the anioiini of nieial Sn is 0.5 to 13 B1iii2.
[Claim 101
20 The chemical treatment steel sheet according to any one of claims 1 to 9, which
is used without performing a coating treatment on the chemical treatment film layer.
[Claim 111
Amethod for producing a chemical treatment steel sheet, comprising:
treating a plated steel sheet having a plating layer, which contains 0.1 to 15 g/m2
25 of Sn in terms of the amount of metal Sn and in which a Sn layer is fonned on a Fe-Sn
alloy layer fonned by alloying a part of or all of Sn through a tin melting treatment, on a
steel sheet in a chemical treatment bath containing 10 to 20000 ppln of Zr ions, 10 to
20000 ppm of fluoride ions, 10 to 3000 ppm of phosphate ions, and 100 to 30000 ppm of
nitrate ions a ~ ~ dsoulrfa te ions to form a chemical treatment film layer on the plating
5 layer,
wherein a temperature of the chemical treatment bath is equal to or higher than
5°C and lower than 90°C, and
the treatment which is performed on the plated steel sheet is an electric field
treatment which is performed for 0.05 to 10 seconds using a current of 0.5 to 20 A/dm2 or
10 an immersion treatment which is performed for 0.2 to 100 seconds.
[Claim 121
The method for producing a chemical treatment steel sheet according to claim
11,
wherein the content of the Zr ions in the chemical treatment bath is 100 to 17000
15 ppnl,
the content of the fluoride ions in the chemical treatment bath is 100 to 17000
PPm,
the cmtent of ?he phosphate ions in the chexica! treaL=ent bath is 20 to 2000
ppm, and
20 the content of the nitrate ions and/or sulfate ions in the chemical treatment bath
is 1000 to 20000 ppm.