DESCRIPTION
TITLE OF INVENTION: ELECTRICAL STEEL SHEET AND METHOD
OF MANUFACTURING THE SAME
TECHNICAL FIELD
[0001] The present invention relates to an
electrical steel sheet used as an iron core material
of an electric apparatus, for example, and a method
of manufacturing the same, and relates to an
electrical steel sheet having an insulating coating
film having good insulation performance, particularly
having good corrosion resistance under a wet
environment and adhesiveness and containing no
chromic acid, and a method of manufacturing the same.
This application is based upon and claims the benefit
of priority of the prior Japanese Patent Application
No. 2010-244030, filed on October 29, 2010, the
entire contents of which are incorporated herein by
reference.
BACKGROUND ART
[0002] When a motor or a transformer is manufactured,
first, a hoop-shaped electrical steel sheet is
punched into a predetermined shape and hoop-shaped
electrical steel sheets are laminated and fixed to
thereby manufacture an iron core. Then, a copper
wire is wound around teeth or/and the like to then be
immersed in a varnish and has powdered paint sprayed
thereon. Thereafter, the iron core has terminals for
connecting the copper wire, flanges, bearings, and so
on attached thereto and is fixed to a case.
- 1 -
[0003] In such a manufacturing process of the iron
core, a facility restriction of a press or the like
is large, and thus there is often a case that a lot
of time is taken for the process in which the
electrical steel sheet is punched into a
predetermined shape.
[0004] Thus, for efficiently performing the punching
process, the hoop-shaped electrical steel sheet is
well prepared beforehand and the process of winding
the copper wire after the punching is performed
collectively, resulting in that an increase in
efficiency is achieved.
[0005] In the case when the hoop-shaped electrical
steel sheets are stored, it is general to use a
depository for preventing rusting, but there is often
a case that the hoop-shaped electrical steel sheets
are left outside the depository for efficiently
performing the punching process, and in this case, it
is necessary to pay attention to rusting particularly.
[0006] Further, in recent years, a process base of
the iron core is shifted to China and Southeast Asia,
and thereby a cost reduction is generally performed.
In such countries, there is often a case that
factories are established under a wet environment
rather than in Japan, and corrosion resistance under
a wet environment is needed rather than in Japan.
[0007] Normally, on the surface of the electrical
steel sheet used for the iron core of an electric
apparatus, an insulating coating film for reducing
- 2 -
eddy current loss is applied, and the insulating
coating film is required to have coating film
properties such as corrosion resistance, adhesiveness,
a punching property, and heat resistance in addition
to insulation performance.
[0008] In this insulating coating film, a mixture
having an inorganic acid salt such as chromate or
phosphate and an organic resin as its main component
is generally contained. In recent years, due to the
environmental concern, an insulating coating film
containing no chromium is required.
[0009] With the progress of an increase in
efficiency of the manufacturing process of the iron
core of an electric apparatus, the insulating coating
film of the electrical steel sheet is required to
have more corrosion resistance than ever, and the
improvement of the corrosion resistance under a wet
environment in particular is required.
[0010] That is, it is sufficient for an insulating
coating film for a conventional electrical steel
sheet to have corrosion resistance enough to be able
to suppress rusting in a depository before the
punching process, but in recent years, corrosion
resistance enough to prevent rusting even under the
wet environment is required.
[0011] Further, it is possible to improve the
corrosion resistance by applying the insulating
coating film thickly, but there are problems that a
space factor decreases and adhesiveness decreases.
- 3 -
- •
[0012] Further, an electrical steel sheet having a
coating material having a fluorocarbon resin as its
main component applied on a surface thereof as the
insulating coating film has problems that cost is
increased and a varnish after the punching does not
adhere to the electrical steel sheet.
CITATION LIST
PATENT LITERATURE
[0013] Patent Literature 1: Japanese Examined Patent
Application Publication No. 50-15016
Patent Literature 2: Japanese Laid-open Patent
Publication No. 03-36284
Patent Literature 3: Japanese Examined Patent
Application Publication No. 49-19078
Patent Literature A: Japanese Laid-open Patent
Publication No. 06-330338
Patent Literature 5: Japanese Laid-open Patent
Publication No. 09-323066
Patent Literature 6: Japanese Laid-open Patent
Publication No. 2002-309379
Patent Literature 7: Japanese Laid-open Patent
Publication No. 05-98207
Patent Literature 8: Japanese Laid-open Patent
Publication No. 07-41913
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0014] Thus, the present invention has been made in
consideration of The above-described problems, and an
object of the present invention is to provide an
- A -
*
electrical steel sheet having more excellent
corrosion resistance under a wet environment and
having good coating film properties, and a method of
manufacturing the same.
SOLUTION TO PROBLEM
[0015] The gist of the present invention is as
follows.
(1} An electrical steel sheet having a surface
thereof coated with an insulating coating film
obtained by mixing
100 parts by mass of a mixture composed of 100
parts by mass of a metal phosphate and 1 part by mass
to 50 parts by mass of an organic resin made of a
mixture or copolymer of one type or two or more types
selected from a group consisting of an acryl-based
resin, an epoxy-based resin, and a polyester-based
resin that have an average particle size of 0.05 /urn
to 0.50 fj. m and
0.5 parts by mass to 10 parts by mass of a
copolymer of a fluoroolefin and an ethylenically
unsaturated compound as a solid content.
(2) An electrical steel sheet having a surface
thereof coated with an insulating coating film
obtained by mixing
100 parts by mass of a mixture composed of 100
parts by mass of colloidal silica and 40 parts by
mass to 400 parts by mass of an organic resin made of
a mixture or copolymer of one type or two or more
types selected from a group consisting of an acryl-
- 5 -
based resin, an epoxy-based resin, and a polyesterbased
resin that have an average particle size of
0.05 y. m to 0.50 fim and
0.5 parts by mass to 10 parts by mass of a
copolymer of a fluoroolefin and an ethylenically
unsaturated compound as a solid content.
(3) A method of manufacturing an electrical steel
sheet includes:
mixing 1 part by mass to 50 parts by mass in
solid content of an organic resin made of a mixture
or copolymer of one type or two or more types
selected from a group consisting of an acryl-based
resin, an epoxy-based resin, and a polyester-based
resin that have an average particle size of 0.05 nm
to 0.50 /i m with 100 parts by mass of a metal
phosphate;
making a treatment solution obtained by mixing
0.5 parts by mass to 10 parts by mass of a copolymer
of a fluoroolefin and an ethylenically unsaturated
compound when converted into a solid content with 100
parts by mass in solid content of a mixture of the
metal phosphate and the organic resin;
applying the made treatment solution on a surface
of the steel sheet; and
baking and drying the steel sheet having had the
treatment solution applied thereon at an ultimate
temperature of 200 CC to 38 0°C for 15 seconds and 60
seconds.
(4) A method of manufacturing an electrical steel
- 6 -
sheet includes:
mixing 40 parts by mass to 400 parts by mass in
solid content of an organic resin made of a mixture
or copolymer of one type or two or more types
selected from a group consisting of an acryl-based
resin, an epoxy-based resin, and a polyester-based
resin that have an average particle size of 0.05 ju m
to 0.50 (jm with 100 parts by mass of colloidal
silica;
making a treatment solution obtained by mixing
0.5 parts by mass to 10 parts by mass of a copolymer
of a fluoroolefin and an ethylenically unsaturated
compound when converted into a solid content with 100
parts by mass in solid content of a mixture of the
colloidal silica and the organic resin;
applying the made treatment solution on a surface
of the steel sheet; and
baking and drying the steel sheet having had the
treatment solution applied thereon at an ultimate
temperature of 200°C to 380°C for 15 seconds and 60
seconds.
ADVANTAGEOUS EFFECTS OF INVENTION
[0016] According to the present invention, it is
possible to obtain an electrical steel sheet coated
with an insulating coating film having good corrosion
resistance under a wet environment and maintaining
coating film properties necessary as an electrical
steel sheet such as adhesiveness, a space factor, and
a punching property.
- 7 -
DESCRIPTION OF EMBODIMENTS
[0017] Hereinafter, a concrete embodiment
implementing the present invention will be explained.
First, as for a steel sheet used in this
embodiment, a steel sheet for a non-oriented
electrical steel sheet containing Si: 0.1 mass% or
more and Al: 0.05 mass% or more is suitable. As for
Si, as the content is increased, electrical
resistance becomes large and a magnetic property
improves, but at the same time, brittleness increases
and a rolling property decreases, and thus less than
4.0 mass% is favorable. Similarly, as the content of
Al is increased, the magnetic property improves, but
the rolling property decreases, and thus less than
3.0 mass% is favorable. In the steel sheet used in
this embodiment, in addition to Si and Al, Mn, Sn, Cr,
and P may also be contained to fall within a range of
0.01 mass% to 1.0 mass%. Further, other
representative elements such as S, N, and C may also
be contained, and the contents of these elements are
preferably less than 100 ppm, and are further
preferably less than 20 ppm.
[0018] In this embodiment, a slab is heated to 1000°C
to 1250°C and is hot rolled to be wound in a coil
shape, and is annealed in a range of 800°C to 1050°C
in a state of a hot-rolled sheet according to need,
and then is cold rolled to be 0.15 mm to 0.5 mm and
further is annealed at 750^ to llOOt, and thereby
the steel sheet having the above-described components
- 8 -
is manufactured.
[0019] Further, on the surface of the steel sheet
where an insulating coating film is formed, before
applying a later-described treatment solution,
arbitrary pretreatments such as a degreasing
treatment by alkali or the like and a pickling
treatment by hydrochloric acid, sulfuric acid,
phosphoric acid, or the like may be performed, or a
surface state obtained after finish annealing may
also be kept without the pretreatments being
performed thereon.
[0020] In the steel sheet used in this embodiment,
it is preferred to finish surface roughness so that
centerline average roughness (Ra) in a rolling
direction and in a direction perpendicular to the
rolling direction may become 1.0 /.i m or less and may
further suitably become not less than 0.1 p. m nor more
than 0.5 M m.
[0021] Next, the insulating coating film to be
formed on the surface of the steel sheet will be
explained. The insulating coating film has a metal
phosphate or colloidal silica as its main component.
[0022] Here, the metal phosphate is one to be a
solid content when an aqueous solution having a
phosphoric acid and metal ions as its main component
is dried, and types of the phosphoric acid are not
limited in particular, but an orthophosphoric acid, a
metaphosphoric acid, a polyphosphoric acid, and the
like are favorable.
- 9 -
[0023] Further, as types of the metal ions, ions
such as Li, Al, Mg, Ca, Sr, Ti, Ni, Mn, and Co are
favorable, and in particular, Al, Ca, Mn, and Ni ions
are favorable. When a metal phosphate solution is
prepared, it is preferably prepared by mixing, for
example, an oxide of metal ion, a carbonate, or a
hydroxide in an orthophosphoric acid.
[0024] The metal phosphate may be used solely or two
or more types may also be mixed and used. Further,
the metal phosphate only is also acceptable, or one
to which an additive such as phosphonic acid or boric
acid is added may also be used.
[0025] On the other hand, as for the colloidal
silica, one having an average particle size of 5 nm
to 40 nm and having an Na content of 0.5 mass% or
less is suitable, and more suitably, the Na content
is 0.01 mass? to 0.3 mass% .
[0026] The average particle size of the colloidal
silica used in this embodiment is.a number average
particle size and is measured by a nitrogen
adsorption method.
[0027] The metal phosphate or colloidal silica, and
an organic resin made of a mixture or copolymer of
one type or two or more types selected from a group
consisting of an acryl-based resin, an epoxy-based
resin, and a polyester-based resin that have an
average particle size of 0.05 ^m to 0.50 ju m, which
will be explained later, are thinly formed on the
surface of the steel sheet as the insulating coating
- 10 -
*
film. Note that the film thickness of the insulating
coating film is preferably 0.3 ti m to 3.0 y.m or so,
and is more suitably 0.5 [i m to 1.5 fi m.
[0028] For the acryl-based resin, the epoxy-based
resin, and the polyester-based resin used in this
embodiment, an organic resin emulsion commercially
available in general may be used. As for suitable
ones, with regard to the acryl-based resin, there can
be cited methyl acrylate, ethyl acrylate, n-butyl
acrylate, i-butyl acrylate, n-octyl acrylate, i-octyl
acrylate, 2-ethylhexyl acrylate, n-nonyl acrylate, ndecyl
acrylate, n-dodecyl acrylate, and the like as a
normal monomer. Additionally, as a monomer having a
functional group, ones obtained by copolymerizing
acrylic acid, methacrylic acid, maleic acid, maleic
anhydride, fumaric acid, crotonic acid, and itaconic
acid are suitable. Further, as a monomer having a
hydroxyl group, ones obtained by copolymerizing 2-
hydroxylethyl (metha) acrylate, 2-hydroxylpropyl
(metha) acrylate, 3-hydroxylbutyl (metha) acrylate,
2-hydroxylethyl (metha) allyl ether, and the like are
suitable.
[0029] In the case of the epoxy-based resin, for
example, there can be cited one obtained by making a
carboxylic anhydride react with an amine-modified
epoxy resin, and concretely, bisphenol A-diglycidyl
ether, a ring-opening adduct of caprolactone of
bisphenol A-diglycidyl ether, bisphenol F-diglycidyl
ether, bisphenol S-diglycidyl ether, novolac glycidyl
- 11 -
•
ether, dimer acid glycidyl ether, and the like are
suitable. Here, as the amine to be modified,
isopropanolamine, monopropanolamine, monobutanolamine,
monoethanolamine, diethylenetriamine, ethylenediamine,
butalamine, propylamine, isophoronediamine,
tetrahydrofurfurylamine, xylenediamine, hexylamine,
nonylamine, triethylenetetramine,
tetramethylenepentamine, diaminodiphenylsulfone, and
the like are suitable. Further, as the carboxylic
anhydride, ones obtained by reaction with succinic
anhydride, itaconic anhydride, maleic anhydride,
citraconic anhydride, phthalic anhydride, trimellitic
anhydride, and the like are suitable.
[0030] As examples of the polyester-based resin,
ones obtained by making dicarboxylic acid such as
terephthalic acid, isophthalic acid, orthophthalic
acid, naphthalene dicarboxylic acid, biphenyl
dicarboxylic acid, succinic acid, adipic acid,
sebacic acid, fumaric acid, maleic acid, maleic
anhydride, itaconic acid, or citraconic acid, and
glycol such as ethylene glycol, 1,2-propylene glycol,
1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
neopentyldiol 1, 6-hexanediol, triethylene glycol,
dipropylene glycol, or polyethylene glycol react with
each other, are suitable. Moreover, acrylic acid,
methacrylic acid, maleic acid, fumaric acid, itaconic
acid, citraconic acid, methacrylic acid anhydride, or
the like may also be graft polymerized with these
polyester-based resins.
- 12 -
[0031] The above-described organic resin emulsion
may be a mixture of one type or two or more types
selected from the group consisting of the abovedescribed
acryl-based resin, epoxy-based resin, and
polyester-based resin, or may also be a copolymer of
these resins. Further, an average particle size of
the above-described organic resin emulsion falls
within a range of 0.05 p. m to 0.50 p. m. Incidentally,
the average particle size of the organic resin
emulsion is a number average particle size and is
measured by a laser diffractometry. This is because
when the average particle size is 0.05 p or less,
the organic resin emulsion aggregates easily in the
treatment solution and the evenness of the insulating
coating film is likely to decrease, and when the
average particle size is larger than 0.50 jum, the
stability of the solution is likely to decrease. If
the stability of the solution deteriorates, there is
sometimes a case that aggregates are generated in the
solution and pipes and pumps are clogged when the
solution is disposed of. Further, when the
aggregates enter the insulating coating film, a
defect is likely to occur in the insulating coating
film. The average particle size of the abovedescribed
organic resin emulsion more suitably falls
within a range of 0.1 /urn to 0.3 um.
[0032] As for a mixing ratio of the metal phosphate
and the organic resin made of the mixture or
copolymer of one type or two or more types selected
- 13 -
from the group consisting of the previously-described
acryl-based resin, epoxy-based resin, and polyesterbased
resin, the above-described organic resin is set
to 1 part by mass to 50 parts by mass relative to 100
parts by mass of the metal phosphate. This is
because when the mixing ratio of the above-described
organic resin is less than 1 part by mass, the
concentration of the resin is too small and thus
aggregates are generated easily and the stability of
the solution deteriorates, and when the mixing ratio
is larger than 50 parts by mass, there is a
possibility that the insulating coating film
deteriorates in heat resistance.
[0033] Further, as for a mixing ratio of the
colloidal silica and the above-described organic
resin, the above-described organic resin is set to 40
parts by mass to 400 parts by mass relative to 100
parts by mass of the colloidal silica. This is
because when the mixing ratio of the above-described
organic resin is less than 40 parts by mass, a film
forming property is poor and the insulating coating
film is likely to generate powder, and when the
mixing ratio is larger than 400 parts by mass, there
is a possibility that the insulating coating film
deteriorates in heat resistance.
[0034] In this embodiment, other than the aboveexplained
components, a copolymer of a fluoroolefin
and an ethylenically unsaturated compound is
contained in the insulating coating film.
- 14 -
[0035] The copolymer of the fluoroolefin and the
ethylenically unsaturated compound to be used in this
embodiment is one obtained by copolymerizing a
fluoroolefin with a monomer, an oligomer, or a lowmolecular
polymer having a radical polymerizable
unsaturated group. Here, the fluoroolefin has an
unsaturated hydrocarbon structure in which fluorine
atoms are directly bonded to a carbon skeleton of
olefin, and is a compound in which at least one of
groups bonded to carbon forming an unsaturated bond
is a fluorine atom. Concretely, there can be cited
tetrafluoroethylene, trifluoroethylene,
hexafluoropropylene, vinylidene fluoride, vinyl
fluoride, trichlorofluoroethylene, and the like. In
this embodiment, one type or two or more types of
them can be used.
[0036] Further, the ethylenically unsaturated
compound has a vinyl group in its structure, can form
a copolymer with a fluoroolefin, is generally called
vinyl ether, and is a monomer, an oligomer, or a lowmolecular
polymer having various functional groups.
As an example of the monomer, for example, styrene,
vinyl acetate, polypropylene glycol acrylate, methoxy
polyethylene methacry1 ate, vinyl alkyl ether, vinyl
alkylene ether, isoprene, acrylonitrile, and the like
are suitable. In addition to these monomers,
oligomers or low-molecular polymers having a similar
structure are also favorable. In this embodiment,
one obtained by introducing various functional groups
- 15 -
into such a monomer, oligomer, or low-molecular
polymer may also be used. As an example of such a
functional group, an alkyl group, a hydroxyl
substituted alkylene group, a phenyl group, a benzyl
group, a cyclic aliphatic group, and an acetyl group
are favorable, or crosslinkable reaction groups such
as a carboxyl group, a hydroxyl group, an epoxy group,
and an amino group are also favorable. Examples of
the alkyl group and the alkylene group are a
straight-chain alkyl group with 1 to 10 chained
carbons (C), and an example of the alkylene group is
a hydroxyl straight-chain alkylene group with 1 to 14
chained C and a hydroxyl group at its terminal, or
the like. Incidentally, it is set that as the
functional groups in this embodiment, a fluoro group
and other functional groups having fluorine atoms are
not included.
[0037] Further, as the ethylenically unsaturated
compound, it is also possible to use ones obtained by
making the monomer, the oligomer, or the lowmolecular
polymer having these functional groups
react with glycidyl methacrylate, hydroxymethyl
acrylate, N,Ndimethylaminoethyl methacrylate,
diacetone acrylamide, butadiene, chloroprene, or the
like.
[0038] In the one obtained by copolymerizing the
fluoroolefin and the ethylenically unsaturated
compound, a portion containing fluorine atoms and a
portion containing no fluorine atoms exist. Thus, by
- 16 -
-
the portion containing fluorine atoms, the heat
resistance and water resistance are maintained, and
at the same time, by functional groups introduced
into the portion containing no fluorine atoms, the
adhesiveness with a base material and flexibility are
maintained. Further, it is designed to prevent a
fluoro group and functional groups having fluorine
atoms from being contained in the portion of the
ethylenically unsaturated compound, thereby making it
possible to obtain the insulating coating film having
improved dispersibility and having excellent evenness.
[0039] These copolymers of the fluoroolefin and the
ethylenically unsaturated compound may be used solely,
or a mixture of two or more types of ones having
different functional groups or ones having different
molecular weights is also favorable.
[0040] A particle size of the copolymer of the
fluoroolefin and the ethylenically unsaturated
compound is not defined in particular, but suitably
falls within a range of 0.05 ju m to 0.50 /im, and more
suitably falls within a range of 0.05 ju m to 0.20 ju m.
When the particle size is less than 0.05 \i m, the
copolymer aggregates easily in the solution and the
stability of the solution is likely to deteriorate.
As described previously, if the stability of the
solution deteriorates, there is sometimes a case that
aggregates are generated in the solution and pipes
and pumps are clogged when the solution is disposed
of. Further, when the aggregates enter the
- 17 -
insulating coating film, a defect is likely to occur
in the insulating coating film. When the particle
size is larger than 0.50 ju m, the insulating coating
film is easily peeled off when being formed and is
likely to generate powder. ' Further, when the
particle size is 0.20 fi m or less, a beautiful
appearance can be obtained easily.
[0041] Next, a mixing ratio of the copolymer of the
fluoroolefin and the ethylenically unsaturated
compound to the mixture of the metal phosphate and
the previously-described organic resin is set to 0.5
parts by mass to 10 parts by mass when converted into
a solid content relative to 100 parts by mass in
solid content of the above-described mixture. This 1
is because when the mixing ratio of the copolymer is
less than 0.5 parts by mass, there is a risk that an
effect of improving the corrosion resistance does not
appear sufficiently, and when the mixing ratio is
larger than 10 parts by mass, the stability of the
solution deteriorates and workability is likely to
decrease.
[0042] Further, a mixing ratio of the copolymer of
the fluoroolefin and the ethylenically unsaturated
compound to the mixture of the colloidal silica and
the previously-described organic resin is also set to
0.5 parts by mass to 10 parts by mass when converted
into a solid content relative to 100 parts by mass in
solid content of the above-described mixture. This
is because when the mixing ratio of the copolymer is
- 18 -
less than 0.5 parts by mass, the effect of improving
the corrosion resistance does not appear sufficiently,
and when the mixing ratio is larger than 10 parts by
mass, the stability of the solution deteriorates.
[0043] Further, in the insulating coating film,
components other than the mixture of the metal
phosphate or the colloidal silica and the previouslydescribed
organic resin, and the copolymer of the
fluoroolefin and the ethylenically unsaturated
compound may also be contained. For example, an
inorganic compound such as carbonate, hydroxide,
oxide, titanate, or tungstate, or an organic lowmolecular
compound such as polyol, cellosolve,
carboxylic acids, ethers, or esters may also be added
as an addi tive.
[0044] Next, in the case when the treatment solution
containing the above-explained components is applied
on the surface of the electrical steel sheet, the
application method is not limited in particular, and
a roll coater method may be used, or an application
method such as a spray method or a dip method may
also be used.
[0045] Further, in the case when a heating method of
drying and baking the treatment solution is used, an
ordinary radiation furnace or air heating furnace can
be used, or an induction heating method, a highfrequency
heating method, or the like may also be
used .
[0046] As drying conditions, for example, the range
- 19 -
of 200°C to 380^ and a baking time from 15 seconds to
60 seconds are appropriate. In the case of the
insulating coating film containing the metal
phosphate, the range of 260°C to 330^ is more
suitable. On the other hand, in the case of the
insulating coating film containing the colloidal
silica, the range of 200t to 300°C is appropriate,
and the range of 240°C to 280t is more suitable.
[0047] Further, an additive such as a surface-active
agent may also be added to the above-described
treatment solution. As the surface-active agent, an
aliphatic polyoxyalkylene ether surface-active agent
is appropriate, and additionally, a brightener, an
antiseptic, an antioxidant, and/or the like may also
be added.
[0048] In the insulating coating film composed of
the above-described copolymer of the fluoroolefin and
the ethylenically unsaturated compound and the
mixture of the metal phosphate or colloidal silica
and the specific organic resin, the copolymer is
dispersed in the insulating coating film. The
dispersed copolymer of the fluoroolefin and the
ethylenically unsaturated compound is concentrated in
the vicinity of a surface layer of the insulating
coating film and surface tension of the insulating
coating film is substantially optimized. As a result,
it is conceivable that the adhesiveness is maintained
and the corrosion resistance under the wet
environment is improved.
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EXAMPLE
[0049] Next, experiments performed by the present
inventors will be explained. Conditions and so on in
these experiments are examples employed to confirm
the applicability and effects of the present
invention, and the present invention is not limited
to these examples.
[0050] First, a steel sheet containing Si: 2.0 mass%,
Al: 0.3 mass%, and Mn: 0.3 mass%, having a sheet
thickness of 0.35 mm, and having surface roughness in
Ra (centerline average roughness) of 0.44 /zra was
prepared. Incidentally, the surface roughness of the
steel sheet was measured by using a commercially
available surface roughness measuring device based on
a JIS method (JIS B0601) .
[0051] Next, mixed solutions No. 1 to No. 15 shown
in Table 1 below were made.
[0052] [Table 1]
PART !RY MASS OP
Xo. BINDER SOLUTION NAME ORGANIC RESIN BESU, OTHER ADDITIVES
1 ALUMINUM PHOSPHATE ACRYL-BASED RESIN 1 20
2 NICKEL PHOSPHATE ACRYL-BASED RESIN 1 15
3 MANGANESE PHOSPHATE EPOXY-BASED RESIN 1 8 PHOSPHONIC ACID 1.5
4 ALUMINUM PHOSPHATE POLYESTER-BASED RESIN 40
5 COLLOIDAL SILICA ACRYL-BASED RESIN 1 100
6 COLLOIDAL SILICA EPOXY-BASED RESIN 1 80
7 ALUMINUM PHOSPHATE ACRYL-BASED RESIN 2 30
8 ALUMINUM PHOSPHATE EPOXY-BASED KESIN 2 30
9 ALUMINUM PHOSPHATE ACRYL-BASED RESIN 1 0. 5
10 CALCIUM PHOSPHATE POLYESTER-BASED RESIN 60
11 ALUMINUM PHOSPHATE AQUEOUS POLYURETHANE 30
12 COLLOIDAL SILICA EPOXY-BASKD RESIN 2 30
13 COLLOIDAL SILICA ACRYL-BASED RESIN 1 30
14 COLLOIDAL SILICA ACRYL-BASED RESIN 1 450
J5 MAGNESIUM CHROMATE ACRYL-BASED RESIN 1 30
- 21 -
[0053] As the metal phosphate, an orthophosphoric
acid and a metal hydroxide such as A1(0H)3, an oxide,
or a carbonate were mixed and stirred to thereby
prepare a metal phosphate treatment solution, which
was set to an aqueous solution of 40 mass%.
Incidentally, as a reference example, a magnesium
chromate aqueous solution of 40 mass% was also
prepared.
[0054] For the colloidal silica, commercially
available one with a concentration of 30 mass% having
an average particle size of 15 nm and having its
surface modified by aluminum was used.
[0055] Further, with regard to the organic resin,
six types of organic resins shown below were each set
as an emulsion solution with a concentration of 30
mass?. Further, proper amounts of a viscosity
modifier and a surface-active agent were added to
make the mixed solutions shown in Table 1.
[0056] (1) Acryl-based resin 1: an acryl-based resin
obtained by copolymerizing 30 mass% of methyl
methacrylate, 10 mass% of 2-hydroxyethyl raethacrylate,
30 mass% of n-butyl acrylate, 10 mass% of styrene
monomer, and 20 mass% of isobutyl acrylate
(2) Acryl-based resin 2: an acryl-based resin
obtained by copolymerizing 45 mass% of methyl
acrylate, 30 mass% of styrene monomer, 20 mass% of
isobutyl acrylate, and 15 mass% of maleic acid
(3) Epoxy-based resin 1: a carboxyl-group modified
- 22 -
epoxy-based resin obtained by modifying bisphenol A
by triethanolamine and then making succinic anhydride
react therewith
(4) Epoxy-based resin 2: an epoxy-based resin
obtained by mixing an ethylene propylene block
polymer with a phenol-novolac epoxy resin and adding
a nonylphenyl ether ethylene oxide thereto, thereby
making it a self-emulsifying type
(5) Polyester-based resin: a polyester-based resin
containing a carboxyl group obtained by
copolymerizing 35 mass% of dimethyl terephthalate and
35 mass% of neopentyl glycol and then graft
polymerizing 15 mass% of fumaric acid and 15 mass% of
trimellitic anhydride
(6) Aqueous polyurethane: aqueous polyurethane
synthesized from hexamethylene diisocyanate and
polyethylene glycol by an already-known method
[0057] Incidentally, average particle sizes of the
acryl-based resin 1 and the acryl-based resin 2 were
0.25 fi m and 0.64 ju m respectively. Further, average
particle sizes of the epoxy-based resin 1 and the
epoxy-based resin 2 were 0.33 /JHI and 0.76 p
respectively. Further, an average particle size of
the polyester-based resin was 0.35 JX m, and an average
particle size of the aqueous polyurethane was 0.12 ,u m.
Note that parts by mass of resins shown in Table 1
are values converted into a.solid content.
[0058] Further, to the mixed solution No. 3, as an
additive, 1.5 parts by mass of phosphonic acid was
- 23 -
added relative to 100 parts by mass of manganese
phosphate.
[0059] Next, treatment solutions obtained by adding
predetermined amounts of copolymers of a fluoroolefin
and an ethylenically unsaturated compound or
fluorocarbon resins shown in Table 2 below to these
mixed solutions shown in Table 1, and treatment
solutions obtained by adding nothing to the mixed
solutions shown in Table 1 were made. Note that the
fluorocarbon resin added amounts (parts by mass)
shown in Table 2 are values converted into a solid
content.
[0060] [Table 2]
- 24 - I
MIXED TYPE OF FLOOROCAKBOH ,„„,, rgmaxr^ X
% SOLUTION FLUOROCARBON "ESIH AnDED TIME NOTE
No. RESIN STar^s) « - « « »>
1 I COPOLYMER l 2 320t;x20 SS^r"
2 1 COPOLYMER 2 ,\ 280'C X 3 0 ^ ^ °K
3 2 COPOLYMER 3 8 280CC x 20 S£S°N
4 2 COPOLYMER 2 4 330°Cx15 SSS™
5 3 COPOLYMER 2 0.8 260CC x 40 S^S°H
6 4 COPOLYMER 2 6 330^x35 5 ^ °"
7 5 COPOLYMER 2 1 200t: x 4 0 g^0N
8 5 COPOLYMER 2 6 280*Cx30 ££!£°B
9 6 COPOLYMER 2 3 350cCx20 gEg"
10 1 FLUOROCARBON RESIN 1 \ 200^X40 SS^S*1™
11 1 FLUOROCARBON RESIN 2 \ 280CC x 3 0 g^SS"1*
12 7 COPOLYMER 4 2 300t: x 1 5 £££TIVE
13 8 COPOLYMER 4 2 280tx40 g^gS"1"5
14 9 COPOLYMER 2 4 330T; x 2 0 gggS"™
15 10 COPOLYMER 3 6 400^ x 5 g£!f "*
1 6 II COPOLYMER 2 4 260^x20 SSSS"*1
17 12 COPOLYMER 2 6 330^x40 £^STIVE
18 13 COPOLYMER 2 4 260°Cx35 ^ ^ I TC
19 14 COPOLYMER 3 2 300CC x 2 0 g ^ "™
20 1 NONE 320X: x 2 0 gSS'"'
21 2_ COPOLYMER l 0. 2 200t: x 2 5 ^SSS"™
2 2 2 COPOLYMER 1 14 180^x70 £EE"™
23 3 FLUOROCARBON RESIN 3 20 280°C X 3 0 %£££™
24 5 COPOLYMER 2 0. 4 250'C x 5Q ££££""*
25 5 COPOLYMER 2 12 250'C x 2 0 S ^ "™
26 I 15 | NONE 330tx30 S ^ (
[0061] The copolymer 1 shown in Table 2 is one
obtained by copolymerizing tetrafluoroethylene and
straight-chain alkyl vinyl ether with a carbon number
of 6, and the copolymer 2 is one obtained by
copolymerizing tetrafluoroethylene and methyl vinyl
ether. The copolymer 3 is one obtained by
- 25 -
copolymerizing chlorotrifluoroethylene, propylene
alkyl vinyl ether, and hydroxyhexyl vinyl ether and
then substituting a hydroxyl group with a carboxyl
group. The copolymer 4 is one obtained by
copolymerizing each of chlorotrifluoroethylene and
hydroxydodecyl vinyl ether by an already-known method.
As the already-known method of copolymerization, for
example, the method disclosed in Japanese Patent No.
3117511 is suitable, and further as the method of
substituting a hydroxyl group with a carboxyl group,
the method disclosed in Japanese Examined Patent
Application Publication No. 58-136605 can be used.
The fluorocarbon resin 1 is polytetrafluoroethylene,
and the fluorocarbon resin 2 is polyvinylidene
fluoride. Further, the fluorocarbon resin 3 is
perfluoro alkoxy alkane.
[0062] A roll coater method was used for applying
the treatment solutions, and a roll reduction amount
and so on were adjusted so that the film thickness of
the insulating coating film might become about 0.8 urn.
The drying was performed by using a radiation furnace,
and furnace temperature setting was adjusted so that
the predetermined heating conditions shown in Table 2
could be obtained. Ultimate sheet temperatures and
baking times differ depending on samples, but a
heating temperature was adjusted to fall within a
range of 180°C to 400°C and the baking time was
adjusted to be 5 seconds to 70 seconds.
[0063] On the other hand, the average particle size
- 26 -
was measured beforehand. The organic resin emulsion
was diluted with distilled water, and a fluorocarbon
resin powder was dispersed in distilled water for
about one minute by an ultrasonic cleaner, and then a
number average particle size was measured with a
commercially available particle size measuring device
using a laser diffractometry based on a JIS method
(JIS Z8826).
[0064] Hereinafter, a method of evaluating
manufactured samples No. 1 to No. 26 will be
explained in detail.
With regard to the insulation performance, based
on interlayer resistance measured based on a JIS
method (JIS C2550), the interlayer resistance of
lower than 5 Q •cm2/piece was evaluated as X, the
interlayer resistance of 5 Q • cm2/piece to 10 Q •
cm2/piece was evaluated as A. Then, the interlayer
resistance of 10 Q ' cm'/piece to 50 Q • cm2/piece was
evaluated as O , and the interlayer resistance of 50
Q • cm2/piece or more was evaluated as ®.
[0065] With regard to the adhesiveness, the samples
with an adhesive tape put thereon were wrapped around
metal bars having a diameter of 10 mm, 20 mm, 30 mm,
and then the adhesive tape was peeled off, and the
adhesiveness was evaluated from the peeled state.
One that did not peel even when being bent with 10 mm
was evaluated as 10 mm 0 OK, and hereinafter, one
that did not peel with 20 mm (/> was evaluated as 20 mm
<$> OK, one that did not peel with 30 mm <£ was
- 27 -
4 1
evaluated as 30 mm $ OK, and one that peeled off was
evaluated as OUT.
[0066] With regard to the corrosion resistance under
the wet environment, first, a 5% NaCl aqueous
solution was designed to fall down onto the samples
naturally for one hour in an atmosphere at 35°C based
on a salt spray test of a JIS method {JIS Z2371).
Next, the samples were maintained for three hours at
a temperature of 60°C and a humidity of 40%, and were
maintained for three hours at a temperature of 40°C
and a humidity of 95%, and this was set as one cycle
and was performed repeatedly for five cycles. Then,
a rusted area of each of the samples was evaluated by
10 points. Criteria of evaluation are as follows.
[0067] 10: No rust occurred
9: A quite small amount of rust occurrence (0.1%
or less in area ratio)
8: Area ratio of rust occurred = larger than 0.1%
and 0.25% or less
7: Area ratio of rust occurred = larger than
0.25% and 0.50% or less
6: Area ratio of rust occurred = larger than
0.50% and 1% or less
5: Area ratio of rust occurred = larqer than 1%
and 2.5% or less
4: Area ratio of rust occurred = larger than 2.5%
and 5% or less
3: Area ratio of rust occurred = larger than 5%
and 10% or less
- 28 - ft
2: Area ratio of rust occurred = larger than 10%
and 25% or less
1: Area ratio of rust occurred = larger than 25%
and 50 % or less
[0068] A contact angle was measured by using a
contact angle meter PG-X manufactured by MATSUBO
Corporation. A measurement value is an average value
obtained by the measurement being performed 10 times.
[0069] With regard to the appearance, one being
glossy, smooth, and even was evaluated as 5, and
hereinafter, one being glossy but slightly poor in
evenness was evaluated as 4, one being slightly
glossy and smooth but poor in evenness was evaluated
as 3, one having low gloss, being slightly poor in
smoothness and poor in evenness was evaluated as 2,
and one being poor in all of gloss, evenness, and
smoothness was evaluated as 1.
[0070] with regard to the heat resistance, after
stress relief annealing at 750CC for two hours in a
nitrogen atmosphere being performed, a 2 mm X 30 mm
gauze was rubbed on the surface of the steel sheet
with a load of 100 gf (about 0.98 N), and a peeled
state of the insulating coating film was evaluated.
As a result, one that did not peel was evaluated as 5,
one that slightly peeled was evaluated as 4, one that
clearly peeled off was evaluated as 3, one having a
severe peeled state was evaluated as 2, and one that
peeled off even without being rubbed with the gauze
was evaluated as 1. These evaluation results are
- 29 -
shown in Table 3.
[0071] [Table 3]
CORROSION RESISTANCE IHSBLAHOH CONTACT „ HBAT „„„„
N ° - UNDER WET ENVIRONMENT PERFOSMMCE ADHESIVENESS ^ g ^ . APPEARANCE M S I S T M C E NOTE
1 H) ~" O 20mm i> OK 84° 5 5 HEEF~
2 10 @ 20mm 0 OK 76* 5 4 £%£?"
3 8® 20mm <> OK 72" 4 5 JS^""
4 9 ""O^ 20mmpOK 81° 5 t l ^T
5 8~ Q 20mm ,i)0K""~ 74° 4 4 g^0"
6 _J0 @ 20mm ^ OK 89° 5 4 £££""
7 8 ® 20mns»0K 82° 5 4 S£T
8 7 Q 20nim»0K 71° 4_ 4 g^"*
9 7 O 20mratfOK 72° 4 4 S^°"'
10 3 Q 30nm.o0llT 7]° 4 4 jgSS7™
11 3 @ 30mm e» OUT 68° 1__ _ _ ? ^ _ J ™ ? L ! I _
12 2 @ 30mm»OK 64° 4 2 JS""*
13 6 A 30mm OK 65° 5 5 SSST™
21 3 A 30mnn>0K 57° 2 2 ^^T I T l:
22 6 O 30wmo0l'T 66° 1 4 tZ^1™
23 5 Q 30mm 0OLT 68° 3 4 S^S"1™
24 3 A 30mrodOK 54° 3 2 ££££"'*
25 7 O 20imn