DESCRIPTION
ELECTRICAL STEEL SHEET
TECHNICAL FIELD
[0001]
The present invention relates to an electrical steel sheet.
BACKGROUNDART
[0002]
ln general, when electrical apparatus such as a motor and a kansformer is to be
produced using an electrical steel sheet, firstly a coiled electrical steel sheet is blanked
into a predetermined shape, and then the blanked electrical steel sheets are laminated to
form an iron core and a copper wire is wound around the teeth and others of the iron core.
Subsequently, a terminal for copper wire connection, a flange, and others are attached to
the iron core after it is subjected to impregnation with a vamish and other processes, and
then the iron core is secured to a casing. In this manner, motors, transformers, and others
are produced.
[0003]
For iron core production processes as described above, there is a recent trend
toward eliminating the securement of the iron core to a casing but instead applyrng, to the
outside of the laminated iron core, a powder coating, an electrodeposition coating, or an
aqueous coating so as to enhance corrosion resistance and durability.
[0004]
Powder coating is a type of coating applied by electrostatically depositing, onto
an iron core, a coating powder dispersed in powdered fonn and then drying and curing
the coating so as to coat the iron core entirely. Electrodeposition coating is a type of
coating applied by electrically depositing, onto an iron core, coating particles dispersed
in water and then drying and curing the coating so as to coat the iron core entirely.
Aqueous coating is a type of coating applied by depositing a coating solution onto an iron
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core by spraying of the coating solution or immersion in the coating solution and then
drying and curing the coating so as to coat the iron core entirely.
[000s]
With regard to powder coating, electrodeposition coating, aqueous coating, or
other coatings, there is a possibility that rust may occur in a gap between the coating and
the iron core if adhesion between the coating and the iron core is low, and therefore
adhesion with the iron core is important.
[0006]
The upper and lower surfaces of the laminated iron core are constituted by
surfaces of a surface-treated steel sheet, whereas the side surface portions of the laminated
iron core are constituted by the steel itself, which has been exposed by blanking, and
therefore have different properties from those of the upper and lower surfaces of the iron
core.
[0007]
ln general, electrical steel sheets are provided with an insulating coating on the
surface to reduce eddy current loss. The insulating coating needs to have good coating
properties in terms of not only insulating properties but also corrosion resistance,
adhesion with the steel sheet, punchability, and thermal resistance.
[0008]
As is known, such insulating coatings are typically fonned from a constituent
based on a salt such as a chromate salt and a phosphate salt, an oxide such as colloidal
silica and mica, an organic resin such as an acrylic resin and an epoxy resin, and a mixture
thereof.
[000e]
Examples of technologies related to the insulating coating of an electrical steel
sheet are as follows. JP50-15013, listed below, discloses a technique for forming an
insulating coating using a treafrnent solution based on a bichromate salt and an emulsion
of an organic resin such as a vinyl acetate-acrylic resin copolymer, a butadiene-styrene
copolymer, or an acrylic resin. JP03-36284, listed below, discloses a technique for
forrning an insulating coating using a treatnent solution including a chromic acid aqueous
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solution, an emulsion type resin, and an organic reducing agent, and further including a
readily soluble aluminum compound, an oxide or another compound of a divalent metal
(Me), and H¡BOs, wherein, in the chromic acid solution, the molar ratio of Me2* to Al3*
ranges from 0 to 7 .O,the molar ratio of (Al¡* + Me2*) to CrOs ranges from 0.2 to 0.5, and
the molar ratio of H¡BO¡ to CrO¡ ranges from 0.1 to 1.5.
[0010]
In recent years, with increasing awareness of environmental issues, technologies
have been developed for forrning an insulating coating without using an aqueous solution
of a chromium compound containing hexavalent chromium. Examples of such
technologies are as follows. JP06-330338, listed below, discloses a technique'for
mixing, at a specific ratio, a phosphate salt having a specific composition, at least one
selected from a boric acid and colloidal silica, and an emulsion of an organic resin having
a specific particle size, and baking the mixture onto a steel sheet. This technique uses a
treatment solution free of a chromium compound but can achieve good coating properties
comparable to those of conventional chromium compound-containing insulating coatings,
and in addition, can retain excellent slipperiness after stress relief annealing.
[0011]
JP09-323066, listed below, discloses an electrical steel sheet having, on the
surface, an insulating coating containing an ethylene-unsaturated carboxylic acid
copolymer, an epoxy resin, a silane coupling agent, and silioa at'a specific ratio.
[0012]
JP2002-309379, listed below, discloses an electrical steel sheet for blanking
having excellent slipperiness and adhesion. This electrical steel sheet includes a top
layer coating free of a chromium compound and which contains 40 to 90%o by mass of a
fluorocarbon resin, and an organic resin. JP2002-309379 also discloses that the
fluorocarbon resin contained in the top layer coating is polytetrafluoroethylene, and the
organic resin contained in the top layer coating is one selected from, or a mixture of two
or more selected from a polyethersulfone resin, a polyphenylenesulfide resin,
polyetherketone, and a polysulfone resin.
[0013]
l+
With regard to fluorocarbon resins, JP05-98207 discloses a technique related to
an aqueous coating çemposition containing a fluorine-containing copolymer. This
fluorine-containing copolymer is a copolymer of a fluoroolefin and an ethylenically
unsaturated compound, and includes 30 to 70o/o of fluoroolef,rn-based units. The
fluorine-containing copolymer has a hydroxyl value of 30 to 200 mg KOFVg, an acid
number of 2 to 200 mg KOWç, and a number average molecular weight of 3000 to 40000.
[0014]
JP07-4I913 discloses a technique related to an electrical steel sheet including an
insulating coating formed of a phosphate salt and an organic resin. WO 2012/57168
discloses a technique for fonning an insulating coating with good adhesion to an electrical
steel sheet by mixing, at a specific ratio, a copolymer of a fluoroolefin and an
ethylenically unsaturated compound with a mixture of a metal phosphate and an acrylic
resin, an epoxy resin, or a polyester resin, having a specific particle size.
[001s]
WO 20I2/0II442 discloses a technique related to an electrical steel sheet
provided with an insulating coating including a first component, which includes a metal
phosphæe and an acrylic resin, an epoxy resin, or a polyester resin, or a mixture or a
copolymer thereof, having a specific particle size, and a second component, which
includes a dispersion or a powder of a fluorocarbon resin having a specific particle size.
LIST OF PRIORART DOCUMENTS
PATENT DOCUMENT
[0016]
Patent Document 1: JP50-15013
Patent Document 2: JP03-36284
Patent Document 3: JP06-330338
Patent Document 4: JP09-323066
Patent Document 5: JP2002-309379
Patent Document 6: JP05-98207
Patent Document 7: JP07-4I913
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Patent Document 8: WO 2012157168
Patent Document 9: WO 2012/011442
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0017]
In production processes for iron cores for eleckical apparatus, it is necessary that
good adhesion be ensured for powder coating, electrodeposition coating, and aqueous
coating, and also necessary that the side surfaces of the lamination of the iron core and
the upper and lower steel sheet surface portions of the iron core have comparable coating
compatibilities.
[0018]
However, in conventional electrical steel sheets fonned using the techniques
disclosed in JP50-15013, JP03-36284, JP06-330338, JP09-323066, JP2002-309379,
JP05-98207, JP07-41913,'WO 2012157t68, and, WO 2012/011442, mentioned above,
there are difflerences between the coating compatibilities of the insulating coatings and
the coating compatibilities of the metal exposed side surface portions of the laminations.
This can result in an extremely thin thickness of a coating on the insulating coating
portions, which leads to a low corrosion resistance, or can result in an exfremely large
thickness of a coating on the side surfaces of the laminations, which leads to a low
adhesion, and furthermore can result in non-uniforrrity of the coating on the insulating
coating portions, which leads to the occurrence of uneven coating, and even further, can
result in failure to produce practically any corrosion resistance improvement effect of
powder coating, electrodeposition coating, or aqueous coating.
[001e]
Furthermore, when the insulating coating on the surface of an elecfrical steel
sheet is formed using a high molecular weight fluorocarbon resin as a base component,
as disclosed n JP2002-309379, JP05-98207, and Vy'O 2012/011442 descnbed above,
problems arise, for example, of high costs and low adhesion of a coating after blankingln
addition, high molecular weight fluorocarbon resins have poor dispersibility. Thus,
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there is a problem in that stirring for a long time causes the fluorocarbon resin to form
large clusters and this results in non-uniform concentration of the fluorocarbon resin in
the surface of the insulating coating.
[0020]
The present invention has been made in view of the problems described above,
and accordingly, an object of the present invention is to provide an electrical steel sheet
having improved coating compatibility and improved corrosion resistance in wet
environments and also having good coatingproperties interms of, for example, insulating
properties, adhesion, appearance, and thermal resistance.
SOLUTION TO PROBLEM
[0021]
The present inventors have solved the problems described above by including a
low molecular weight fluorine-containing compound in the base component of the
insulating coating. The gist thereof lies in the electrical steel sheet set forth below.
[00221
(1) An electrical steel sheet having an insulating coating on a steel sheet"surface,
wherein the insulating coating çsmFrises one or more selected from an inorganic salt, an
oxide and an organis resin, wherein
the insulating coating contains, based on a total qass.of the insulating coating,
50o/o or more by mass in total of: the inorganic salt and/or the oxide,
has a fluorine concentration ranging from 2 ppm to 130 ppm,,and
is free of a chromilm compound.
[0023]
(2) The electrical steel sheet according to the item (1), wherein the insulating
coating contains, based on a total mass of the insulating coating, 500/o or more by mass in
total of: a metal phosphate, and; one selected from, or a mixture or a copolymer of two or
more selected from an acrylic resin, an epoxy resin, and a polyester resin.
100241
(3) The elechical steel sheet according to the item (1), wherein the insulating
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coating contains, based on a total mass of the insulating coating, 50Yo or more by mass in
total of, the oxide, and; one selected from, or a mixture or a copollmrer of two or more
selected from an acrylic resin, an epoxy resin, and a polyester resin.
[002s]
(a) The electrical steel sheet according to the item (2), wherein the insulating
coating contains, based on a total mass of the insulating coating, 50% or more by mass in
total of:
100 parts by mass of the metal phosphate including one or more metal elements
selected from aluminum, zinc, calcium, cobalt, strontium, zirconium, titanium, nickel,
barium, magnesium and manganese, and;
1 to 50 parts by mass of one selected from, or a mixture or a copolymer of two
or more selected from the acrylic resin, the epoxy resin, and the polyester resin.
100261
(5) The elechical steel sheet according to the item (3), wherein the insulating
coating contains, based on a total mass of the insulating coating, 50olo or more by mass in
total of:
100 parts by mass of the oxide including one or more selected from colloidal
silica, zinc oxide, calcium oxide, cobalt oxide, zirconium oxide, titanium oxide and
magnesium oxide and;
1 to 100 parts bymass of one selected from, or a mixture or a copolyner of two
or more selected from the acrylic resin, the epoxy resin, and the polyester resin.
ADVANTAGEOUS EFFECTS OF INVENTION
100271
As described above, in the present invention, a specific fluorine concentation is
given to the insulating coating that contains 50%o or more by mass in total of an inorganic
salt and/or an oxide based on the total mass of the inzulating coating or contains 50o/o or
more by mass in total of a metal phosphate and an organic resin based on the total mass
of the insulating coating. By this means, the present invention provides an electrical
steel sheet having an insulating coating that shows good coating compatibility for
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electrodeposition coating, powder coating, and aqueous coating and also shows good
properties in terms of corrosion resistance in wet environments, insulating properties,
adhesion, appearance, thermal resistance, and other properties.
DESCRIPTION OF EMBODIMENTS
[0028]
A specific embodiment of the present invention will be described.
Io02e]
The present invention relates to an electrical steel sheet that can be used as a
material for iron cores of, for example, electrical apparatus. In particular, the present
invention relates to an electrical steel sheet including an insulating coating that is free of
a chromium compound and showing good insulating properties, adhesion, and corrosion
resistance in wet environments, and also having suitable coating compatibility.
[0030]
An electrical steel sheet according to the present embodiment has, on the steel
sheet surface, an insulating coating that is free of a chromium compound and in which
the fluorine concentation ranges from 2 ppm to 130 ppm. The insulating coating
includes, for example, a mixture of an inorganic salt and/or an oxide in an amount of 50%
or more by mass in total based on the total mass of the insulating coating, or includes, for
example, a metal phosphate and an organic resin, such as an acrylic resin, an epoxy resin,
and a polyester resin, in an amount of 50% or more by mass in total based on the total
mass of the insulating coating.
[0031]
Firstly, the following description is given of an elecüical steel sheet on which
the insulating coating is formed in the present embodiment.
[0032]
In the present embodiment, a suitable example of the electrical steel sheet on
which the insulating coating is formed maybe a non-oriented electrical steel sheet that at
least contains, bymassTo, Si: 0.1% ormore and less tharr-4.0% andAl: 0.05% ormore
and less than3.0%o, with the balance being Fe and impurities. Si increases elecffical
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resistance and improves magnetic properties with the increase in its content, but since Si
decreases rollability, the content is preferably less than 4.0% by mass. Likewise, Al
improves magnetic properties with the increase in its content, but since Al decreases
rollability, the content is preferably less than3.0To by mass. The electrical steel sheet
used in the present embodiment may further contain elements other than Si and Al, such
as Mn, Sn, Cr, and R in an amount ranging from 0.01% by mass to 3-0%o by mass. The
electrical steel shegt used in the present embodiment may contain firrther additional
elements such as S, N, and C in an amount of less than 100 ppm, preferably in an amount
of less than 20 ppm.
[0033]
In the present embodiment, an electrical steel sheet for use may be formed, for
example, by heating a slab having the steel composition described above to 1000 to
l250"C,hot-rolling the slab and winding it into a coil, annealing as necessary the sheet
in the as-hot-rolled condition within a temperature range of 800oC to l050oC, thereafter
cold rolling the sheet to 0.15 to 0.5 mm, and further annealing the sheet at750 to 1100oC.
[0034]
The surface of the electrical steel sheet, on which the insulating coating is to be
forrred, may be subjected to an optional pretreatment prior to application of a treaûrent
solution described below. Examples of the pretreatment include degreasing treaûments
using an alkali or the like and pickling treatnents using a hydrochloric acid, a sulfuric
acid, a phosphoric acid or the like. The surface of the eleckical steel sheet, prior to
application of the treatment solution described below, may not be subjected to any of such
preteatments but maybe the surface in the as-finish-annealed condition.
[003s]
Next, described below is the insulating coating to be forrned on the surface of
the electrical steel sheet in the present embodiment.
[0036]
In the present embodiment, the inorganic salt to be included in the insulating
coating is a salt that contains an acid such as sulfiric acid, nihic acid, or carbonic acid
and metal ions in an amount of 50o/o or more by mass in total based on the total mass of
/,0
the inorganic salt. Specific examples of the inorganic salt include strontium sulfate,
aluminum sulfate, magnesium sulfate, calcium sulfate, aluminum nitrate, iron nitrate,
zirconium carbonate, a double salt of zirconium carbonate and ammonium carbonate,
barium carbonate, magnesium carbonate, zinc oxide, calcium oxide, zirconium oxide,
magnesium oxide, titanium oxide, and cobalt oxide. Specific examples of the oxide to
be included in the insulating coating include metal oxides, silica, and alumina, and more
specific examples include colloidal silica, zinc oxide, calcium oxide, cobalt oxide,
zirconium oxide, titanium oxide, and magnesium oxide.
[0037]
The inorganic salts and the oxides may each be used alone or in combination as
a mixture of two or more.
[0038]
In the present embodiment, there are no particular limitations on the t¡4pe of
phosphoric acid to be included in the metal phosphate that is included in the insulating
coating, but orthophosphoric acid, metaphosphoric acid, and polyphosphoric acid, for
s¡amFle, are preferred. The metal ions to be included in the metal phosphate described
above are preferably ions of Li, Al, Mg, Ca, Sr, Ti, Ni, Mn, Co, Zn, Zr, or Bafor example,
more preferably ions of Al, Zn, Ca, Co, Sr, Zt,Ti, Ni, Ba, Mg, or Mn, and even more
preferably ions ofAl, Ca, Mn, or Ni. Preparation of a solution of the metal phosphate is
preferably carried out, for example, by mixing an oxide, a-carbonate, or a hydroxide of
the above-mentioned metal ions with aphosphoric acid such as orthophosphoric acid and
preparing the solution
[003e]
The metal phosphate may be used as a single phosphate or as a mixture of two
or more phosphates. Furthermore, an additive such as a phosphonic acid or a boric acid
may also be used with the metal phosphate.
t00401
In the present embodiment, among the specific examples of the oxide to be
included in the insulating coating, the colloidal silica may be, for example, a colloidal
silica having an average particle size of 5 to 40 nm and a Na content of 0.5% or less by
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mass. The Na content more suitablyranges from 0.01 to O.3Yoby mass.
[0041]
As used in the present embodiment, the average particle size of the colloidal
silica and the average particle sizes of the organic resins to be described below are number
average values (number average particle sizes) of the diameters of the primary particles
provided that the particle shapes approximate spheres. The average particle size of the
colloidal silica can be measured by the nitrogen adsorption method for example, and the
average particle sizes of the organic resins can be measured by laser diffiactometry for
example.
100421
According to the present embodiment, it is necessary that the fluorine
concentration in the insulating coating range from 2 to 130 ppm. The fluorine
concentration in the insulating coating is preferably not less than 5 ppm, and more
preferably not less than 8 ppm. Furtherrrore, the fluorine concentration in the insulating
coating is preferablynot more than 100 ppm, and more preferably not more than 50 ppm,
and particularly preferably not more than 30 ppm.
[0043]
There are no particular limitations on the method for measuring the fluorine
concentration in the insulating coating, but ion chromatography may be suitably used, for
example. If an interfering element is present among the components of the insulating
coating, a high sensitivity measurement method, such as the combination of ion
chromatography and the lanthanum alizann complexone method as disclosed in JP7-
198704 may be used, for example. By the use of these analysis methods, accurate
quantitative determination of the fluorine concentration in the insulating coating can be
made.
[0044]
The present invention provides, for example, an electrical steel sheet with a thin
insulating coating on the surface, with the coating containing a mixture of an inorganic
salt and/or an oxide in an amount of 50% or more by mass in total based on the total mass
of the coating, and with the fluorine concentration in the coating being within the specifie
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range of 2 to i30 ppm. Furthermore, the present invention provides, for example, an
electrical steel sheet with a thin insulating coating on the surface, with the coating
containing a metal phosphate and an organic resin in an amount of 50o/o or more bymass
in total based on the total mass of the coating, and with the fluorine concentration in the
coating being within the specific range of 2 to 130 ppm. The thicknesses of these
insulating coatings preferably range from 0.3 to 3.0 pm, and more preferably range from
0.5 to 1.5 pm.
[004s]
ln the present embodiment, the acrylic resin, the epoxy resin, and the polyester
resin that can be included in the insulating coating may each be a cornmercially available
resin emulsion.
[0046]
The acrylic resin may be a resin formed from a monomer such as methyl acrylate,
ethyl acrylate, n-butyl acrylate, i-butyl acrylate, n-octyl acrylate, i-octyl acrylate, 2-
ethylhexyl acrylate, n-nonyl acrylate, n-decyl acrylate, and n-dodecyl acrylate, or more
suitably may be a resin formed by copolymenzingthe monomer with a functional groupcontaining
monomer such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride,
fi¡maric acid, crotonic acid, and itaconic acid or with a hydroxyl group-containing
monomer such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,3-
hydroxybutyl (meth)acrylate, and 2-hydroxyethyl (meth)allyl ether.
[0047]
The epoxy resin may be a resin formed by, for example, reacting an aminemodified
epoxy resin with a carboxylic acid anhydride. Specifically, the epoxy resin
may suitably be a resin formed by modifuing an epoxy resin of, for example, bisphenol
A diglycidyl ether, a ring-opened caprolactone adduct of bisphenol A diglycidyl ether,
bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, novolac glycidyl ether, or
dimer acid glycidyl ether, with an amine such as isopropanolamine, monopropanolamine,
monobutanolamine, monoethanolamine, diethylenetriamine, ethylenediamine,
þulalamine, propylamine, isophoronediamine, tetrahydrofurfurylamias, xylenediamine,
hexylamine, nonylamine, triethylenetetramine, tetamethylenepentamine, md
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diaminodiphenyl sulfone, and reacting the modified resin with a carboxylic acid
anhydride such as succinic anhydride, itaconic anhydride, maleic anhydride, citraconic
anhydride, phthalic anhydride, and trimellitic anhydride.
[0048]
The polyester resin may suitably be a polyester resin forrned by reacting a
dicarboxylic acid with a glycol. Examples of the dicarboxylic acid include 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, and citraconic acid, and examples of the glycol include
ethylene glycol, 1,2-propylenglycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol,
neopentyldiol, 1,6-hexanediol, triethylene glycol, dipropylene glycol, and polyethylene
glycol. Furthermore, the polyester resins described above may be graft polymerized
with, for example, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid,
citraconic acid, or methacrylic acid anhydride, and the resultant resins may be used.
[004e]
The emulsion of the organic resin may be an emulsion of one of the abovementioned
organic resins or may be an emulsion of a mixture of two or more of the abovementioned
organic resins. The emulsion of the organic resin preferably has an average
particle size of 0.05. to 0.50 pm. If the average particle size is less than 0.05 pm, the
organic resin tends to agglomerate in the treaûnent solution ard this may reduce the
uniformity ofthe insulating coating. Thus, such an average particle size is not prefened.
If the average particle size is more than 0.50 ¡rm, the stability of the treatment solution
may decrease, and therefore such an avetage particle size is not preferred. More
preferably, the average particle size of the emulsion of the organic resin ranges from 0.1
to 0.3 pm.
[00s0]
In the case where a metal phosphate and one or more organic resiis selected
from an acrylic resin, an epoxy resin, and a polyester resin are to be included in the
insulating coating, the mixing ratio of the organic resin preferably ranges from I to 50
parts by mass based on 100 parts by mass of the metal phosphate. If the mixing ratio of
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the organic resin is less than 1 part by mass, the concentration of the organic resin is
extremely low, which likely causes agglomeration of the organic resin and may result in
low stability of the treatrnent solution. Thus, such a mixing ratio is not preferred. If
the mixing ratio of the organic resin is more than 50 parts by mass, the thennal resistance
of the insulating coating may decrease, and therefore such a mixing ratio is not preferred.
More preferably, the mixing ratio of the organic resin ranges from 6 to 25 parts by mass
based on 100 parts by mass of the metal phosphate.
[00s1]
In the case where an oxide such as colloidal silica and one or more organic resins
selected from an acrylic resin, an epoxy resin, and a polyester resin are to be mixed into
the insulating coating, the mixing ratio of the organis resin preferably ranges from I to
100 parts by mass based on 100 parts by mass of the oxide. If the mixing ratio of the
organic resin is less than 1 part by mass, the film forming properties for the insulati:rg
coating are poor and chalking may occur on the insulating coating. Thus, such a mixing
ratio is not preferred. If the mixing ratio of the organic resin is more than 100 parts by
mass, the thennal resistance of the insulating coating may decrease, and therefore such a
mixing ratio is not preferred. More preferably, the mixing ratio of the organic resin
ranges from 5 to 80 parts by mass based on 100 parts by mass of the oxide.
[00s2]
The insulating coating of the electrical steel sheet.accordi.g to the present
embodiment is to contain fluorine at a concentration of 2 to 130 ppm. To accomplish
this, a fluorine-containing compound, for example, is added to the insulating coating.
Suitable examples of the fluorine-containing compound may include low molecular
weight fluorine compounds, fluorocarbon rubbers, and fluorocarbon resins, each in
emulsion forrn, finely dispersed in an aqueous solution. When a water-soluble fluorinecontaining
compound is used, the fluorine-containing compound may be simply added
and mixed without emulsification in an appropriate manner.
[00s3]
Examples of the low molecular weight fluorine compound may include a
fluorochemical surfactant and a fluorocarbon oil. Specific examples of the
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fluorochemical surfactant include salts of perfluorobutanesulfonic acid, perfluoroalkyl
ethylene oxide adducts, and perfluoroalkyl group-containing amine neutralized phosphate
esters. Exam¡les of the fluorocarbon oil include chlorotrifluoroethylene low polymers,
perfluoropolyether low polymers, perfluoroalkyl polyether low polymers, fluorinemodified
silicones.
[00s4]
Suitable examples of the fluorocarbon rubber may include a vinylidene fluoride
copolymer. Specific examples of the vinylidene fluoride copolymer may include
vinylidene fluoride-tehafluoroethylene copolymers, vinylidene fluoridehexafluoropropylene
copolymers, vinylidene fluoride-tehafluoroethylene-propylene
copolyners, md vinylidene fluoride-hexafluoropropylene{etrafluoroethylene
copolyurers.
[00ss]
Examples of the fluorocarbon resin may include pol¡etrafluoroethylene,
polychlorotrifluoroethylene, fluoroethylene-vinyl ether copolymers such âs
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-ethylene
copolyners, tetrafluoroethylene-hexafluoropropylene copolyners, polyvinylidene
fluoride, and ethylene-chlorofrifluoroethylene copolymers. h addition, various
modifications of these fluorocarbon resins and copolymers of the fluorocarbon resins with
other copolymerizable resins, for example, may also be used.
[00s6]
The low molecular weight fluorine compound, the fluorocarbon rubber, the
fluorocarbon resin, and their copolyners described above refer to relatively low
molecular weight compounds, i.e., so-called oligomer compounds, .among fluorinessafainiag
compounds. The molecular weights of the low molecular weight compound,
the fluorocarbon rubber, the fluorocarbon resin, and their copolymers are preferably not
less than 200 and more preferably not less than 1,000, and preferably not more than
100,000 and more preferably not more than 20,000- The low molecular weight fluorine
compound, the fluorocarbon rubbeç the fluorocarbon resin, and their copollnners may be
used alone, or a mixture of two or more of them, with different functional groups and./or
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different molecular weights for example, tây be used.
[00s7]
Among the above-mentioned fluorine-containing compounds, water soluble
compounds may be directly mixed with the treatment solution. However, the
fluorocarbon rubber ahd the fluorocarbon resin may preferably be emulsified using, for
example, a fluorochemical surfactant before being mixed with the treatment solution.
The particle size for emulsification is not particularly limited but, for example, it is
suitably within a range of 0.05 to 0.50 pm, and more suitably within a range of 0.05 to
0.20 ¡rm. If the pârticle size of the primary particles is less than 0.05 ¡rm, the fluorinecontaining
compound tends to agglomerate in the solution, which can decrease the
stability of the solution, and therefore such a particle size is not preferred. If the particle
size of the primaryparticles is more than 0.50 ¡un, the fonned insulating coating is prone
to delamination and mayhave chalking, and therefore such aparticle size is notpreferred.
In particular, decreased solution stability is not preferred because it can cause
agglomerations in the solution and the agglomerations may clog the pipe or pump or may
be included in the insulating coating to cause coating defects. On the other hand, if the
particle size of the primary particles is not more than 0.20 pm, the resulting insulating
coating will likely have a good appearance, and therefore such a particle size is more
preferred. Specifically, the particle size of the fluorine-containing compound when it is
in emulsion form is a number average particle size and can-be nreasured, for example, in
accordance with a JIS method (JIS 28825-1) using a commercially available laser
diftaction/scattering particle size distributi on analyzer.
[00s8]
The mixing ratio of the fluorine-containing compound and the material that
forms the base component of the insulating coating (one selected from, or a mixture of
two or more selected from an inorganic material, an oxide, and an organic resin, or a metal
phosphate and an organic resin) is not particularly limited as long as the predetermined
fluorine concentration is achieved. Suitably, the fluorine-containing compound may be
mixed with the insulating coating in an amount of 0.3 to 50 parts by mass based on 100
parts by mass of the solids content of the material that fomrs the base component of the
fi:,:
i.:'
il.
H-_1
F,:
r(lï+
...;.
insulating coating. Amixing ratio of the fluorine-containing compound of less than 0.3
parts by mass is not preferred because it may lead to non-uniform distribution of fluorine
in the insulating coating,"and a mixing ratio of the fluorine-containing compound of more
than 50 parts by mass is not p*referred because it results in fomration of some high fluorine
concentration portions in the insulating coating, which may decrease the coating
compatibility. More preferably, the mixing ratio of the fluorine-containing compound
ranges from 0.5 to 5 parts by mass based on 100 parts by mass of the solids content of the
material that forms the base component of the insulating coating. Herein, by "base
component" is meant that the component is contained in an amount of 50% by mass or
more based on the total mass of the insulating coating.
[00se]
In the present embodiment, it is also possible to add, to the insulating coating, a
component other than the above-described material that forms the base component of the
insulating coating and the fluorine-containing compound. For example, low molecular
weight organic compounds of, for example, polyol, cellosolve, carboxylic acids, ethers,
or esters, may further be included as an additive in the insulating coating.
[0060]
In the present embodiment, the electrical steel sheet having the insulating coating
on the surface can be produced by using an electrical steel sheet having the composition
described above, applying thereto a treatment solution containing the components
described above, and then subjecting it to heating, and baking and drying.
[0061]
ln the present embodiment, there are no particular limitations on the coating
method for application of the teatnent solution to the surface of the electrical steel sheet.
For example, a roll coater method may be used to apply the treatment solution to the
surface of the electrical steel sheet, or a coating method such as a spray method or a dip
method may be used to apply the solution to the surface of the electrical steel sheet.
[0062]
Also, there are no particular limitations on the heating method for baking and
drying the treatrnent solution. For example, it is possible to use a coÍlmon radiation
: Ìi
ts
,ì";
s.
i":
'J
i,: . l.l
i::
.:
fumace or air heating furnace, or to use an induction heating method or a high-frequency
heating method.
[0063]
As for the conditions for baking and drying the treahent solution, for example,
the heating temperature is preferably within a range of 200 to 380"C and the baking time
preferably ranges from 15 to 60 seconds. If the heating temperature is less than 200oC,
the moisture in the insulating coating cannot be removed thoroughly, and therefore such
a temperature is not preferred. If the heating temperature is more than 380"C, the
organic resin therein begins combusting, and therefore such a temperature is not preferred.
Furthermore, if the baking time is less than 15 seconds, uniform heating is difficult and
therefore such a baking time is not preferred, and if the baking time is more than 60
seconds, the industrial costs increase greatly, and therefore such a baking time is not
preferred. Furtherrnore, in the case where the treatment solution contains a metal
phosphate, the heating temperature is more preferably within a range of 260 to 330oC,
and in the case where the treatuent solution contains colloidal silica, the heating
temperature is more preferably within a range of 200 to 300oC and even more preferably
is within a range of 240 to 280'C.
[0064]
Furthermore, additives such as a swfactant may be added to the treatment
solution. Preferred examples of the surfactant include aliphatic polyoxyalþlene ether
surfactants, and examples of other additives that may be added include brighteners,
preservatives, and antioxidants.
[006s]
In the present invention, the fluorine-containing compound is mainly present in
the surface layer in the insulating coating and thereþ imparts water and oil repellency to
the surface of the insulating coating. However, if the surface is entirely coated with the
fluorine-containing compound, a problem arises in that the compatibility with a coating
composition decreases and therefore the coating adhesion decreases. For this reason,
the present invention employs the specific range of fluorine concentration so that the
surface coating by the fluorine-containing compound constitutes part of the coating.
r1{ tî
This configuration is believed to optimize
electrodeposition coating compatibility of the
corrosion resistance in wet environments.
the powder coating compatibility or
insulating coating and also improve its
EXAMPLE
[0066]
Firstly, a non-oriented electrical steel sheet was prepared which contained, by
mass, Si: 2-4yo,Al: 0.3%, Mn:0.5Yo, and the balance: Fe and impurities and which had a
sheet thickness of 0.35 mm.
[0067]
Next, metal phosphate solutions were prepared using an orthophosphoric acid as
metal phosphate in the following manner. Hydroxides, oxides, or carbonates of metals,
e.8., Mg(OH)z and Al(OH)r, were each dissolved in water together with the
orthophosphoric acid so as to obtain a metal phosphate concentration of 40% by mass,
and each solution was mixed and stirred.
[0068]
In addition, as the inorganic salt or oxide, fine particles of titanium oxide,
magnesium oxide, and zirconium hydroxide (mass average particle size of less than 1
¡rm) (commercial products) and aluminum surface modified 30 mass % colloidal silica
with an average particle size of 15 nm (commercial product) were used. These inorganic
salts or oxides were each dispersed in water so as to obtain a concentration of 40% by
mass, and thereby inorganic solutions were prepared. It is believed that the hydroxide
(zirconium hydroxide) was partially converted to an oxide (zirconium oxide) as a result
of heating for application and drying.
[006e]
As for the organic resins, the following 4 types of 40 mass % emulsions were
used.
[0070]
(1)Acrylic Resin
An emulsion of an acrylic resin formed by copolymerizing 30% by mass of
¡,l
1."
ll
!:'
\1y2þ
methyl methacrylate, lÙYo by mass of 2-hydroxyethyl methacrylate,30o/o by mass of nbutyl
acrylate,I0o/o bymass of a styrene monomer, and20% bymass of isobutyl acryIate
(2) Epoxy Resin
An emulsion of a carboxyl group modified epoxy resin fomred by modiffing
bisphenol A with triethanoiamine and reacting it with succinic anhydride
(3) Polyester Resin
An emulsion of a carboxyl group-containing polyester resin formed by
copolymerizng35o/o by mass of dimethyl terephthalate and 35%by mass of neopentyl
glycol and then graft polym enzingthe copolymer with l5%by mass of fumaric acid and
l1%by mass of trimellitic anhydride
t00711
Furthennore, as the fluorine-containing compound, compounds listed in Table 1
were each added and mixed so as to obtain a fluorine concentration shown in Table 1.
100721
[Table 1]
!:
È
i:
l1
{u
Irventive Exanple 1
Inventive Exanple 2
r[l?
Pr
Irventive Exanpb 3
Inventive Exauple 4
Metal plnsphate softfion
or inorganic solr¡tbn
Irventive Elønpþ 5
Compound
Inventive E>ønpþ 6
Al(HuPO¿)a
Inventive Exanpb 7
A(H2PO4)3+Ni(H2PO4h
(70 :30)
Mn(H2P04)2
Inventive Exarple 8
A(H2PO4)3 + colloidal silica
(80 :20)
Ratb
þartby massl
Irventive Exanple 9
Table I
Conrparative Exarmle 1
Conparative Exanple 2
Colbidal silica
Tl),
Zr{OH) 2 + c olloft lal s ilie a
100
Cornparative Emuurle 3
100
',}rg-ty¡1"..;7'1
Organb resin
Conparative E carpb 4
Compound
Tioz+ zf(oE)z
(20 :80)
100
Acrylic Resin
Reference Exarmle
Acrylic Resin
100
MgO+TO2
(50 :50)
Ratb
þartby massl
Acrylic Resin
A(H2PO4)3+ ZnGIzPOq)z
(50 :50)
100
A(II2PO4)3
100
100
Ftrorine-containirg
compound
Poþester Resin
20
40
Compound
Epory Resin
100
Mamesinn chromiate
Al(HrPOo).
5
Acrylic Resin
100
A
Ratb
[partby mass]
Acrylic Resin
A
100
70
c
100
Acrylic Resin
Fluorine
corpentration
(ppm)
60
l0
Acrylic Resin
c
20
20
100
Epoxy Resin
B
30
100
30
E
Acrvlic Resin
25
30
F
50
J
Acrylic Resin
30
30
45
D
40
60
36
10
D
100
130
10
97
30
A
20
6
B
B
9
100
24
30
50
240
56
220
',r'-r:-:.r.i(ìt^..1:''¡-:r,'t l
il
tr
,).
[0073]
In Table 1, the letters rrArr to "F" represent the following fluorine-containing
compounds and the synbol "-" indicates that no such compound was used.
A: vinylidene fluoride-hexafluoropropylene
B : tetrafluoroethylene-vinyl ether low copolymer
C: salt of perfluorobutanesulfonic acid
D: perfluoroalkyl polyether low polym.er
E: fluorine-modifi ed silicone
F: chlorotrifluoroethylene low polyner
[0074]
ln Table 1, the metal ion fractions are mass fractions and thq contents of the
organic resins and the fluorine-containing compounds are based on the solids content.
. [007s]
Treatnent solutions having mixing ratios shown in Table 1 were each applied to
the surface of the electrical steel sheet having the composition described above, and
baking was performed at drying temperatures shown in Table 2, so as to prepare eleckical
steel sheets of Examples 1 to 9, Comparative Examples 1 to 4, and Reference Example.
A roll coater method was employed for the application of the feaûnent solution to the
surface of the electrical steel sheet, and the amount of roll pressure and others were
adjusted so as to obtain an insulating coating thickness of approximately 0.8 ¡rm. The
drying was performed using a radiation furnace. The end-point sheet temperatures and
the baking times were adjusted so that the end-point sheet temperatures were within a
range of 200 to 360'C and the baking times were within a raage of 10 to 60 seconds,
depending on the samples.
t00761
The fluorine concentration was analyzedby a combustion-ion chromatography
method. The measurement was made by an analysis technique in accordance with a JIS
method (JIS K0102) and using a commercially available ion chromatograph.
100771
In the following, the method for evaluating the produced samples will be
.:
tI
l¡
j
¿l
çe-,
g:
'î z-s
il
i
described in detail.
[0078]
The insulating properties were evaluated as follows based on interlayer
resistances measured in accordance with a JIS method (JIS C2550): less than 5
Ç).cm2lsheet as "x"; 5 O or more.cm2lsheet and less than 10 f)'cm2lsheet as "4"; 10 Q or
more.cm2lsheet and less than 50 f¿.cm2lsheet as "O"; and 50 or more O.cm2lsheet as "O".
As for the insulating properties, samples evaluated as "O" or "O" were determined to be
acceptable.
[007e]
As for the adhesion, each steel sheet sample, with an adhesive tape attached
thereto, was wound around metut U*t of 10 mm, 20 rnm,and 30 mm in diameter and then
the adhesive tape was peeled offfrom each steel sheet sample, and evaluations were made
based on the occwïence of delamination in the insulating coatings. Samples that did not
have delamination in the insulating coating at the curvature of 10 mm 0 were evaluated
as "10 mm ö OK", samples that did nothave delamination in the insulating coating at the
curvature of 20 mm $ were evaluated as "20 mm S OK", samples that did not have
delamination in the insulating coating at the curvature of 30 mm $ were evaluated as "30
mm $ OK", and samples that had delamination in the insulating coating at the curvature
of 30 rrm Q were evaluated as "30 mm 0 OUT". As forthe adhesion, samples evaluated
as "10 mm S OK", "20 mm 0 OK", or "30 mm 0 OK" were determined to be acceptable.
[0080]
Corrosion resistance in wet environments was evaluated in accordance with a
JIS salt spraytest (JIS 2237I). Firstly, a 5% NaCl aqueous solution was allowed to drop
naturally onto each sample for t hour in an atmosphere at 35oC, and thereafter the sample
was subjected to 5 cycles of holding with one cycle including 3 hours of holding at a
temperature of 60oC and a moisture content of 40% and 3 hours of holding at a
temperature of 40'C and a moisture content of 95%. Subsequently, the area of rust was
evaluated by a l0-point evaluation. The evaluation criteria are as follows. As for the
corrosion resistance, samples evaluated as 7 or higher were determined to be acceptable.
li!:
ß.'l
10: No rust forming
w
ü
ti.
ri'
'ì
:i
9: Very slight rust forrning (area fraction of not more than 0.1%)
8: Area fraction of rust : more tban}.IYo and not more than 0.25%
7: Areafraction of rust: more than}.25Yo and not more than 0.50%
6: Area fraction of rust: more than 0.50% and not motelhanl/o
5: Area fraction of rust: more thanl%o and not morethanZ.S%o
4: Area fraction of rust: more than2-5Yo and not more than 5%
3: Area fraction of rust : more than SYo and not more than 10%
2; Area fraction of rust: more than 10% and not morcthan21Yo
l: Area fraction of rust : more thanZí%o and not more than 50%
[0081]
As for the powder coating compatibility, firstly, a commercially available low
temperature cwe polyester powder coating solution was sprayed onto each sample using
a tribo gun so as to obtain an average coating thickness of 50 pm, and each sample was
heat cured at 160'C for 15 minutes. Subsequently, each coated sample was subjected to
salt spraying over 100 hours and then a cross-cut adhesion test was conducted to evaluate
the powder coating compatibility. ln the cross-cut adhesion test, samples in which the
powder coating did not delaminate were evaluated as "O", samples in which the powder
coating slightly delaminated were evaluated as "O ", samples in which the powder coating
partially delaminated but adhered were evaluated as "4", and samples in which the
powder coating was corroded and had blistering were evaluated as "x". As for the
powder coating compatibility, samples evaluated as "O" or "O" were determined to be
acceptable.
[0082]
As for the electrodeposition coating, ñrstly, a surface pretreaûnent was
performed using a commercially available degreasing solution, and then, a high
weatherability electodeposition coating solution of epoxy-acrylic type was applieil onto
each sample in a bath at 25oC so as to obtain an average coating thickness of 20 pm.
The coated samples were rinsed with water to clean off an excess of the coating
composition and then heat dried at 160"C for 20 minutes. Subsequently, each coated
sample was subjected to salt spraying over 80 hours and then a cross-cut adhesion test
[.
:.': ù:
2,4>ç
was conducted to evaluate the electrodeposition coating compatibility. In the cross-cut
adhesion test, samples in which the electodeposition coating did not delaminate were
evaluated as "O", samples in which the electrodeposition coating slightly delaminated
were evaluated as "O", samples in which the electrodeposition coating partially
delaminated but adhered were evaluated as "4", and samples in which the
electodeposition coating was corroded and had blistering were evaluated as "x". As for
the elecfodeposition coating compatibility, samples evaluated as "O" or "O" were
determined to be acceptable.
[0083]
As for aqueous coating compatibility, firstly, a commercially available acrylic
resin aqueous coating composition was sprayed to obtain an average coating thickness of
10 pm, and then the coating was dried at room temperature and visually evaluated.
Samples in which the aqueous coating was glossy and uniform were evaluated as "5",
samples in which the aqueous coating was glossy but slightly less uniform were evaluated
as "4", samples in which the aqueous coating was less uniform but was totally applied
were evaluated as "3", samples in which the aqueous coating was less unifomr and
partially thin were evaluated as "2", and samples in which the aqueous coating was
entirely non-uniform were evaluated as "f i. As for the aqueous coating,compatibility,
samples evaluated as "3" or higher were deterrnined to be acceptable.
[0084]
As for the appearance, samples whose insulating coating was glossy, smooth,
and uniforrr were evaluated as "5", samples whose insulating coating was glossy but
slightly less unifomr were evaluated as "4", samples whose insulating coating was
somewhat glossy and smooth but less unifomr were evaluated as "3", samples whose
insulating coating was less glossy, somewhat less smooth, and less uniforrn were
evaluated as "2",and samples whose insulating coating was less glossy, less uniform, and
less smooth were evaluated as "1". As for the appearance, samples evaluated as "4" or
higher were determined to be acceptable.
[0085]
As for the thermal resistance, after the electical steel sheet was subjected to
I
21
2-6
stress relief annealing at 7 50"C for 2 hours in a nitrogen atmosphere, the surface thereof
was rubbed with a gauze measuring 2 mm x 30 mm at a loading of 100 gf (approximately
0.98 N), and then evaluations were made based on the occlurence of delamination in the
insulating coating. Samples that did not have delamination after rubbing with the gauze
were evaluated as "5", samples that had slight delamination were evaluated as "4",
samples that had apparent delamination were evaluated as "3", samples that had severe
delamination v/ere evaluated as "2", and samples that had delamination even without
rubbing with the garrze were evaluated as "1". As for the therrral resistance, samples
evaluated as "4" or higher were determined to be acceptable.
[0086]
The above results of evaluations of the electrical steel sheets are summarized in
Table2.
[0087]
fTable 2]
I':
F:?
T>+
Irwentive Exarnole I
Test No.
Inventive E>ørnple 2
Irver¡tive E>ømple 3
Ir¡ventive Example 4
Invertive Example 5
Irsulating
nronerfies
k¡ventive E>ørnole 6
Irventive Erørnple 7
\t.9
ñ{
Inver¡live Example 8
o
Irwentive Example 9
Comparative Example I
o
Adhesion
Co¡nnarative Exarnole 2
o
20mmó OK
Compa¡ative Example 3
o
20mmö OK
Comparative Example 4
o
20mmô OK
o
Refererpe Example
Conosbn
resistarce
20mm0 OK
o
20mmô OK
o
20mmô OK
o
l0
20mm0 OK
o
10
Powder coating
cornoatibilitv
20mmó OK
o
Table2
10
30mmS OK
o
1
20mmö OK
o
9
30mmó OUT
o
o
7
30mmö OK
o
8
30mmó OUT
o
ElecÍodeposfion coating
comoatibilitv
9
20mm0 OK
o
'l
o
7
o
8
o
2
o
o
9
o
o
8
o
^
o
Aqueous coating
comnafi'hilitv
A
o
o
o
^
o
o
o
5
o
5
Appearance
4
X
^
4
o
J
5
Thermal
resistance
J
^
4
5
o
5
5
5
5
5
4
5
5
5
5
2
4
5
3
4
4
,)
4
4
5
3
4
4
5
2
5
5
4
5
4
4
4
5
..', ) --1.:;¡ Q;¡)rr. n-;r¡-
[0088]
Reference to the results shown in Table 2 clarifies the advantageous effects of
the present invention.
[008e]
The results in Table 2 demonstrate that Examples 1 to 9 of the present invention
have excellent powder coating compatibility, electrodeposition coating compatibility, and
aqueous coating compatibility. The results also demonstate that Examples 1 to 9 of the
present invention have excellent insulating properties, adhesion, corosion resistance,
appearance, and thermal resistance, in addition to excellentpowder coating compatibility,
electrodeposition coating compatibility, and aqueous coating compatibility. Specifically,
it is seen that Examples I to t have insulating properties, adhesion, corrosion resistance,
powder coating compatibility, electrodeposition coating compatibility, aqueous coating
compatibility, appearance, and thermal resistance that are comparable to or better than
those of Reference Example, which includes a chromium compound-containing
insulating coating.
[00e0]
On the other hand, with regard to Comparative Examples 1 to 4, most of them
have low powder coating compatibility, electrodeposition coating compatibility, and
aqueous coating compatibility, and none of them are excellent in all the categories of
insulating properties, adhesion, corrosion resistance, powder coating compatibility,
electrodeposition coating compatibility, appearance, and thermal resistance.
[00e1]
Specifically, it is seen that Comparative Example 1, which does not include a
fluorine-containing compound, has low powder coating compatibility and
electodeposition coating compatibiliry and also does not have a good appearance.
Furthermore, it is seen that Comparative Example 2,whichhas a fluorine concentration
higher than the range of the present invention, has low powder coating compatibiliry
eleckodeposition coating compatibility, and aqueous coating compatibility and also has
low adhesion. Furthermore, it is seen that Comparative Example 3, which does not
I
t..
i,:,:1
t..;:
f-'
t. -
å-'.
i{
ii!
-ri
i::
:,r.
7a:
i...
t:
i
f
rì
t! g
Ë..
t::
t-q:i
T-1
contain an inorganic salt or oxide, or, a metal phosphate, has poor corrosion resistance
and appearance. Furthermore, it is seen that Comparative Example 4, which does not
include an organic resin, has low powder coating compatibility, electrodeposition coating
compatibility, and aqueous coating compatibility, and also has low adhesion.
[00e2]
As described in the foregoing, the electrical steel sheet according to the
embodiment of the present invention shows good coating compatibility for powder
coating, electrodeposition coating, and aqueous coating for production of laminate iron
cores, and the insulating coating shows good properties for the electrical steel sheet.
[00e3]
In the foregoing description, a preferred embodiment of the present invention
has been described in detail, but the present invention is not limited to such examples.
It will be apparent that those having general knowledge in the field to which the present
invention belongs may find various altemations and modifications within the scope of the
technical ideas described in the appended claims, and it should be understood that they
will naturally come under the technical scope of the present invention.

We claim:
l. An electrical steel sheet having an insulating coating on a steel sheet surface,
wherein the insulating coating comprises one or more selected from an inorganic salt, an
oxide and an organic resin, wherein
the insulating coating contains, based on a total mass of the insulating coating,
50%o or more by mass in total of: the inorganic salt and./or the oxidp,
has a fluorine concentration ranging &om 2 ppm to 130 ppm, and
is free of a chromium compound.
2. The electuical steel sheet according to claim 1, wherein the insulating
coating contains, based on a total mass of the insulating coating, 50olo or more by mass in
total of: a metal phosphate, and; one selected from, or a mixture or a copolymer of two or
more selected from an acrylic resin, an epoxy resin, and a polyester resin.
3. The electrical steel sheet according to claim 1, wherein the insulating
coating contains, based on a total mass of the insulating coating, 50Yo or more by mass in
total of: the oxide, and; one selected from, or a mixture or a copolymer of two or more
selected from an acrylic resin, an epoxy resin, and a polyester resin.
4. The electrical steel sheet according to claim 2, wherein the insulating
coating contains, based on a total mass of the insulating coating, 50% or more by mass in
total of:
100 parts bymass of the metal phosphate including one or more metal elements
selected from aluminum, zinc, calcium, cobalt, strontium, zirconium, titanium, nickel,
barium, magnesium and manganese, and;
1 to 50 parts by mass of one selected from, or a mixture or a copolymer of two
or more selected from the acrylic resin, the epoxy resin, and the polyester resii.
5. The electrical steel sheet according to claim 3, wherein the insulating
í-.
/3Ud
!:l
1l
coating contains, based on a total mass of the insulating coating, 50o/o or more by mass in
total of:
100 parts by mass of the oxide including one or more selected from colloidal
silica, zinc oxide, calcium oxide, cobalt oxide, zirconium oxide, titanium oxide and
magnesium oxide and;
1 to 100 parts by mass of one selected from, or a mixture or a copolymer of two
or more selected from the acrylic resin, the epoxy resin, and the polyester resin.