JP3369940B2 - Manufacturing method of electrical steel sheet for bonded iron core with excellent adhesive strength, corrosion resistance and blocking resistance - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to punching, shearing,
The present invention relates to a method for producing an electromagnetic steel sheet for an adhesive iron core, which is used by adhering by pressure / heating (thermocompression bonding) after processing such as press working.

[0002]

2. Description of the Related Art Iron cores generally used in electric equipment such as motors and transformers are manufactured by punching or shearing a magnetic steel sheet having an insulating coating on the surface to reduce eddy current loss. , Laminated and then fixed by welding, caulking or adhesive.

However, in the fixing method by welding or caulking, the insulating film is destroyed and the iron core is electrically short-circuited, which causes an increase in eddy current loss, and mechanical or thermal strain deteriorates the magnetic characteristics. It has the drawback of being prone to occur. In addition, in the fixing method using an adhesive, it is necessary to apply the adhesive to each of the punched or sheared steel sheets, which requires a lot of time and labor, resulting in poor work efficiency.

In contrast to the above-mentioned conventional technique, an adhesive type insulating film capable of obtaining an adhesive action by pressurizing and heating (thermocompression bonding) is formed on the surface of the magnetic steel sheet in advance, thereby omitting the adhesive applying step. An electromagnetic steel sheet for an adhesive iron core made possible is known, and the following techniques have been proposed for this. (1) Japanese Patent Publication No. 52-8988 discloses a surface-coated steel sheet for laminated iron core, which is obtained by applying a treatment liquid obtained by emulsifying a solvent-type thermoplastic resin and a thermosetting resin with an emulsifier to a steel sheet surface and then drying it. Has been done.

(2) Japanese Patent No. 2574698 discloses a thermoplastic acrylic resin emulsion (A) having a glass transition point of 60 ° C. or higher, an epoxy resin emulsion (B), an amine-based epoxy resin curing agent and a specific film-forming aid. A water-based adhesive type insulation coating composition containing an agent as a main component and having a resin solid content weight ratio of component (A) and component (B) of (A) / (B) = 70/30 to 95/5 is applied to a steel plate surface. A coated and dried magnetic steel sheet for a bonded iron core is shown.

(3) Japanese Patent Laid-Open No. 7-308990 discloses that
The main components are an acrylic emulsion resin (A) having a glass transition point of 80 to 130 ° C. and a functional group capable of reacting with an epoxy group in the molecule, and an epoxy resin emulsion (B) having a melting point or softening point of 70 to 140 ° C. And ingredient (A)
And the resin solid content weight ratio of the component (B) is (A) / (B) = 9.
Heating having a mixed resin film of 5/5 to 70/30 and having a gelation rate of the mixed resin film in the range of 10 to 90% by weight and showing sufficient adhesive strength even in a high temperature environment of 150 ° C. or higher. A surface coated electrical steel sheet for bonding is shown.

(4) Japanese Patent Application Laid-Open No. 7-268307 discloses that
A water-based heat-adhesive coating composition comprising a thermoplastic resin emulsion having a glass transition point of 80 ° C. or higher, an epoxy resin emulsion, and an aqueous phenol resin and having excellent high-temperature adhesive strength is disclosed. (5) In Japanese Patent No. 2529053, an acrylic resin emulsion and an epoxy resin emulsion which do not contain a nitrogen atom and a sulfur atom in a monomer, and an acid anhydride type epoxy curing agent which reacts with an epoxy resin or a methylol group-containing initial condensation A method for producing a surface-coated magnetic steel sheet for adhesion, which has less odor during coating and drying or aluminum die-casting, is characterized in that a mixed solution containing a substance as a main component is applied to the surface of the steel sheet and dried.

(6) Japanese Patent No. 2613725 discloses that an acrylic-modified epoxy resin emulsion in which a latent curing agent is preliminarily blended on the surface of a steel sheet (after the latent curing agent is blended in the epoxy resin, it is reacted with the acrylic resin to form an epoxy resin). It is characterized by coating the periphery of resin and latent curing agent, then applying a mixed solution containing the emulsion as the main component, and baking it in an incomplete state. A method for producing a surface-coated magnetic steel sheet for adhesion with low odor is shown.

[0009]

However, the surface-coated magnetic steel sheet for an adhesive iron core obtained by these conventional techniques has the following problems.
There are the following problems. The surface-coated steel sheet of (1) above,
About 40% or more of the base resin in the coating consists of a thermoplastic resin, so some adhesive strength at room temperature can be obtained, but under high temperature environment the thermoplastic resin softens and a sufficient level of adhesive strength is obtained. Absent. In addition, since a large amount of emulsifier is used for making it aqueous, it is also inferior in corrosion resistance.

In the above-mentioned (2) electromagnetic steel sheet for an adhesive iron core, 70% or more of the base resin in the coating is made of a thermoplastic resin.
Although the adhesive strength at room temperature can be obtained to some extent, a sufficient level of adhesive strength cannot be obtained due to softening of the thermoplastic resin in a high temperature environment. The surface-coated electromagnetic steel sheet in (3) above has 15
Although the adhesive strength in a high temperature environment of 0 ° C. or higher is improved, as is clear from the examples, the epoxy resin emulsion is emulsified by the forced emulsification method using an emulsifier, so that the emulsifier is formed in the film. The hydrophilic groups remaining in the emulsifier component cause a hygroscopic effect,
It has the disadvantage of poor corrosion resistance.

The adhesive type insulating film obtained by the water-based heat-adhesive type coating composition of the above (4) can provide sufficient adhesive strength when the film thickness is relatively thick, about 10 μm (dry film thickness). In the case of a relatively thin film thickness of 5 to 6 μm (dry film thickness) or less, sufficient adhesive strength cannot be obtained. Surface-coated electromagnetic steel sheet obtained by the manufacturing method of (5) above,
Although the generation of odor during coating and drying or during aluminum die casting is improved, a sufficient level of adhesive strength in a high temperature environment cannot be obtained. The surface-coated electrical steel sheet of (6) above is excellent in adhesive strength at room temperature and after long-term storage, but inferior in high temperature environment.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and to have sufficient adhesive strength not only at room temperature but also at a high temperature of about 150 ° C. after being heat-pressed as an iron core material, Another object of the present invention is to provide a method for producing an electromagnetic steel sheet for an adhesive iron core, which is excellent in blocking resistance and corrosion resistance as the electromagnetic steel sheet for an adhesive iron core.

[0013]

[Means for Solving the Problems] The inventors of the present invention have keenly studied the relationship between the coating composition of an electrical steel sheet for an adhesive iron core and the manufacturing conditions thereof, and the adhesive strength, corrosion resistance, blocking resistance, etc. under normal temperature and high temperature environments. As a result of repeated studies, the following findings were obtained. 1) By using a water-based epoxy resin as the main component of the base resin that constitutes the coating composition, it is possible to obtain excellent adhesive strength under normal temperature and high temperature environments. In particular,
The morphology of the base resin in the coating composition has a great influence on the performance of the electromagnetic steel sheet for an adhesive iron core, and the average particle size of the epoxy resin in the coating composition is 0.05 to 2 μm, Excellent adhesive strength and good corrosion resistance and blocking resistance are obtained.

2) By using a phenol resin as an epoxy resin curing agent constituting the coating composition,
The high temperature adhesive strength can be effectively improved without deteriorating the blocking resistance and the corrosion resistance. further,
High-temperature adhesive strength is further improved by adding a phenolic resin and a latent curing agent as a curing agent.

The present invention has been made on the basis of such findings, and its features are as follows. [1] As a resin component, 1 to 40 parts by weight of a curing agent is added to 100 parts by weight of an epoxy resin having an average particle size of 0.05 to 2 μm.
A water-based coating composition mixed in a ratio of parts by weight (solid content) was applied to at least one surface of an electromagnetic steel sheet in a dry film thickness of 1.0.
~ 12 μm, and reach a plate temperature of 100 ~ 3
A method for producing an electromagnetic steel sheet for an adhesive iron core, which is excellent in adhesive strength, corrosion resistance, and blocking resistance, which is characterized by baking at a temperature of 00 ° C.

[2] In the manufacturing method of the above-mentioned [1], at least a part of the curing agent is a phenol resin, which is excellent in adhesive strength, corrosion resistance and blocking resistance. Method. [3] In the production method of the above [1] or [2], the curing agent is composed of a phenol resin and a latent curing agent, and the amount of the latent curing agent is 2 relative to 100 parts by weight of the phenol resin in terms of solid content. To 200 parts by weight, a method for producing an electromagnetic steel sheet for an adhesive iron core, which is excellent in adhesive strength, corrosion resistance and blocking resistance.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below together with the reasons for limitation. The object of the production according to the method of the present invention is an electromagnetic steel sheet for an adhesive iron core having an insulating film (adhesive insulating film) capable of obtaining an adhesive action by pressurizing and heating (thermocompression bonding). In the present invention, the steel plate serving as the substrate on which the adhesive insulating film is to be formed is an electromagnetic steel plate for iron core used in electric equipment such as motors and transformers. As such an electromagnetic steel sheet, a non-oriented electrical steel sheet or a grain-oriented electrical steel sheet is generally used, but in addition to this, a mild steel sheet, a stainless steel sheet, other special steel sheet, etc. may be used, and the steel sheet serving as a substrate is not limited. . The effects of the present invention can be obtained when any of these steel plates is used as the substrate.

The electromagnetic steel sheet used as the substrate has one or two kinds of surface treatment such as a zinc-based plating or other metal plating film, a chemical conversion film, an inorganic or inorganic-organic insulating film, etc. on its surface. In the present invention, the surface of the electrical steel sheet refers to the surface of the uppermost coating when these surface-treated coatings are provided.

In the production method of the present invention, a film is formed by applying an aqueous coating composition containing an aqueous resin and a curing agent as the main components on the surface of the above electromagnetic steel sheet and baking it to form a film. An epoxy resin having a diameter of 0.05 to 2 μm is used. First, the present inventors examined the relationship between various water-based resins that are base resins for water-based coating compositions and adhesive strength, and found that epoxy-based resins were the most suitable as the base resin for water-based coating compositions. .

The coating composition No. of the examples described later 38,
No. As shown in the comparative example using No. 39, when acrylic resin or urethane resin is used as the base resin of the water-based coating composition, the adhesive strength at room temperature is obtained, but the sufficient adhesive strength in a high temperature environment is obtained. Can't get
This is because the acrylic resin is a thermoplastic resin, which causes the film to soften at high temperatures, resulting in poor high-temperature adhesive strength, and the urethane resin tends to dissociate urethane bonds at high temperatures. It is considered that this is because sufficient high temperature adhesive strength cannot be obtained.

On the other hand, a film made of an epoxy resin and its curing agent exhibits excellent adhesive strength under both normal temperature and high temperature environments. This is because the epoxy resin and the curing agent form a three-dimensional crosslinked structure by thermocompression bonding during iron core production,
It is considered that this crosslinked structure is unlikely to cause softening of the film even in a high temperature environment, and thereby excellent high temperature adhesive strength can be obtained.

Further, it is necessary to use an epoxy resin having an average particle diameter of 0.05 to 2 μm, and this makes it possible to obtain a film excellent in both adhesive strength, blocking resistance and corrosion resistance for the first time. it can. That is, even if the average particle size of the epoxy resin particles in the coating composition exceeds 2 μm or is less than 0.05 μm, a film satisfying all of the adhesive strength, blocking resistance and corrosion resistance cannot be obtained. From the viewpoint of obtaining these properties in a well-balanced manner, the epoxy resin particles have a more preferable average particle diameter of 0.05 to 1 μm, and further, by setting the average particle diameter of 0.1 to 0.5 μm, particularly excellent adhesion is obtained. Strength, blocking resistance and corrosion resistance are obtained.

The epoxy resin used in the present invention is liquid or solid at room temperature and has two or more epoxy groups in the monomer, specifically bisphenol A type, bisphenol F type, bisphenol. A
Various epoxy resins such as D type, naphthalene type, phenol novolac type, orthocresol novolac type, glycidyl ester type and alicyclic type can be mentioned.

The form of the water-based epoxy resin is
Emulsion type epoxy resin obtained by performing forced emulsification in the presence of an emulsifier, after reacting the polybasic acid and the epoxy resin, water-soluble epoxy resin water-solubilized by neutralizing at least a part of the carboxyl group, There are water-dispersed epoxy resins that utilize protective colloids of acrylic resins, but any water-based epoxy resin can be used in the present invention, and as long as the average particle diameter of the epoxy resin is within the above range, these The effect of the present invention can be obtained regardless of the form. However, when particularly severe corrosion resistance is required, it is most preferable to use a water-dispersed epoxy resin.

As the curing agent used in the coating composition, a generally used epoxy resin curing agent can be used. For example, aliphatic polyamine, alicyclic polyamine, aromatic polyamine, polyamide polyamine, modified polyamine and the like can be used. Such polyamine curing agents; monofunctional acid anhydrides (phthalic anhydride, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic acid anhydride, chlorendic acid anhydride, etc.), 2
Functional acid anhydrides (pyromellitic anhydride, benzophenone tetracarboxylic acid anhydride, ethylene glycol bis (anhydrotrimate), methylcyclohexene tetracarboxylic acid anhydride, etc.), free acid anhydrides (trimellitic anhydride, poly Acid anhydride type curing agents such as azelaic acid anhydride); methylol group-containing initial condensates such as novolac or resol type phenolic resins, urea resins, melamine resins; latent curing agents, etc. At least one of the above can be used.

The amount of the curing agent compounded in the coating composition is 1 to 40 relative to 100 parts by weight of the epoxy resin in terms of solid content.
Parts by weight. If the compounding amount of the curing agent is less than 1 part by weight, sufficient curing is not performed during thermocompression bonding, resulting in poor adhesive strength. On the other hand, if the amount of the curing agent compounded exceeds 40 parts by weight, the coating composition thickens and the film-forming property deteriorates, resulting in poor corrosion resistance and adhesive strength.

As the curing agent, a phenol resin is particularly preferable because the adhesive strength in a high temperature environment is remarkably improved. It is considered that this is because the heat resistance of the coating is improved by introducing a benzene ring into the coating. Examples of the phenol resin include a resol-type phenol resin having a methylol group introduced by condensation reaction of phenols such as phenol and bisphenol A with formaldehyde in the presence of a reaction catalyst.

Further, the combined addition of the phenolic resin and the latent curing agent in a specific ratio further improves the adhesive strength of the film. That is, a phenolic resin and a latent curing agent are added together as a curing agent, and the compounding amount of the latent curing agent is 2 to 200 parts by weight, and particularly preferably 3 to 100 parts by weight based on 100 parts by weight of the phenol resin. By using the weight part, the adhesive strength is further improved.

In order to investigate the proper range of the compounding amount of the latent curing agent when the phenol resin and the latent curing agent are added in combination, the epoxy resin (shown in Table 1) is formed on the surface of the electromagnetic steel sheet having a thickness of 0.5 mm. Base resin No. 4): 100 parts by weight (solid content), phenol resin (phenol resin shown in Table 2): 5 parts by weight (solid content), and phenol resin 10
An aqueous coating composition in which the compounding amount (solid content) of the latent curing agent (latent curing agent described in Table 2) per 0 part by weight was changed was applied so that the dry film thickness was 6 μm, and the ultimate plate temperature was 200 ° C. An electromagnetic steel sheet for an adhesive iron core was prepared by baking with the above method, and the influence of the compounding amount of the latent curing agent on the high temperature adhesive strength (this high temperature adhesive strength was evaluated by the evaluation method described in Examples described later) was investigated. .

The results are shown in FIG. According to the figure, even if the compounding amount of the latent curing agent with respect to 100 parts by weight of the phenol resin is less than 2 parts by weight or exceeds 200 parts by weight,
No remarkable high temperature adhesive strength has been obtained by the combined addition of the phenolic resin and the latent curing agent. Further, particularly, the compounding amount of the latent curing agent is 3 to 100 parts by weight of the phenol resin.
The best high temperature adhesive strength is obtained in the range of 100 parts by weight.

As the latent curing agent used in the present invention,
Dicyandiamide, melamine, organic acid dihydrazide, amine imide, ketimine, tertiary amine salt, imidazole salt, boron trifluoride amine salt, microcapsule type curing agent (encapsulating the curing agent in microcapsules formed with casein, etc. A micro-capsule that breaks by pressure and undergoes a curing reaction with the resin), a molecular sieve type curing agent (a curing agent adsorbed on the surface of an adsorbing compound, which releases adsorbed molecules by heating and undergoes a curing reaction with the resin. Stuff) and the like.

The coating composition used in the present invention is mainly composed of a base resin composed of the above-mentioned specific water-based epoxy resin and an epoxy resin curing agent. , Does not interfere with the inclusion of some other base resin component, for example, acrylic resin, polyurethane resin, polyamide resin, polyimide resin, polyester resin, scree cone resin, fluorine resin, polyethylene, polypropylene 35% by weight of synthetic resin such as nylon, elastomer such as nylon, polysulfide, nitrile rubber, chloroprene rubber, polyvinyl formal, etc. in the resin component of the coating composition.
The following may be included. In addition to these, oxide fine particles such as silica and alumina, a conductive substance, a rust preventive additive such as a poorly soluble chromate, a coloring pigment (for example, a condensed polycyclic organic pigment, a phthalocyanine organic pigment, etc.), Coloring dyes (for example, azo dyes, azo metal complex salt dyes, etc.), film forming aids,
It is also possible to blend one or more kinds of dispersibility improvers, defoamers and the like.

In the production method of the present invention, the coating composition is applied to the surface of an electromagnetic steel sheet and baked to form a film for laminating adhesion.
12 μm. When the film thickness is less than 1.0 μm, the adhesive strength is insufficient, while when the film thickness exceeds 12 μm, not only the adhesive strength is saturated, but also the space factor decreases, which is not preferable. From the viewpoint of such adhesive strength and space factor, a more preferable film thickness is 3 μm to 7 μm. The method of applying the coating composition to the steel plate surface is arbitrary. Usually, it is applied by a roll coater method, but it is also possible to adjust the application amount by an air knife method or a roll drawing method after applying by a dipping method or a spray method.

The baking treatment after applying the coating composition can be carried out using a hot air oven, a high frequency induction heating oven, an infrared oven or the like. The baking temperature is 100 to 3 at the ultimate plate temperature.
Set to 00 ° C. When the reached plate temperature is less than 100 ° C., the coating film is not sufficiently hardened before thermocompression bonding for manufacturing the iron core, resulting in poor corrosion resistance and blocking resistance. On the other hand, when the reached plate temperature exceeds 300 ° C, the coating before thermocompression bonding is excessively hardened, and the coating does not sufficiently soften and melt during thermocompression bonding, so that the interfaces between the films do not melt and the adhesive strength is Will be inferior. From this point of view, a more preferable baking temperature is 130 to 230 ° C., whereby particularly excellent adhesive strength, corrosion resistance and blocking resistance can be obtained.

The temperature rising rate during the baking treatment is not particularly limited, but is preferably about 3 to 80 ° C./sec. Temperature rising rate is 3
If it is less than 80 ° C / sec, the production efficiency of the steel sheet is poor, which is not preferable. On the other hand, if it exceeds 80 ° C / sec, the coating film may be cracked, and the appearance of the coating film tends to deteriorate.

[0036]

[Example] A magnetic steel sheet having a thickness of 0.5 mm was coated with a coating composition by a roll coater and then baked to produce a magnetic steel sheet for an adhesive iron core, and the adhesive strength of the obtained electromagnetic steel sheet for an adhesive iron core was obtained. , Blocking resistance, and corrosion resistance were evaluated. The composition of the base resin used in the coating composition is shown in Table 1, the curing agent is also shown in Table 2, the composition of the coating composition is shown in Tables 3 to 5, and the production conditions (baking temperature and drying) of the magnetic steel sheet for adhesive iron core are shown. The film thickness) and the results of performance evaluation are shown in Tables 6 to 10. The method for preparing the coating composition and the method for evaluating each performance of the magnetic steel sheet for the adhesive iron core are shown below.

[Preparation of Coating Composition] The base resins (epoxy resins) shown in Table 1 and the curing agents shown in Table 2 were used, and these were mixed and stirred, and Nos. Shown in Tables 3 to 5 were used. 1-No.
37 coating compositions were obtained. The proportion of non-volatile components in these coating compositions was all 20 wt%. In addition, N shown in Table 5
o. No. 38 acrylic resin emulsion and No. 38 acrylic resin emulsion. The urethane resin emulsion of 39 is obtained by the following. (a) Acrylic resin emulsion: A monomer mixture consisting of 90 parts by weight of methyl methacrylate, 15 parts by weight of styrene, 10 parts by weight of acrylic acid and 10 parts by weight of ethyl acrylate was emulsion polymerized in water by a conventional method to prepare an acrylic resin emulsion. (b) Urethane resin emulsion: "Adeka Bonder HUX-240" manufactured by Asahi Denka Co., Ltd. was used.

[Evaluation of Performance of Electromagnetic Steel Sheet for Adhesive Iron Core] (a) Film of magnetic steel sheet for adhesive iron core cut to a size of 25 mm × 50 mm in room-temperature adhesive strength so that the overlapping portion becomes 25 mm × 12.5 mm Overlapping formation surfaces, pressure 10kgf
In the state of pressurizing at / cm ² , thermocompression bonding was performed according to the temperature rising pattern shown in FIG. This was pulled by a tensile tester in a normal temperature atmosphere, the maximum load until breaking was measured, and the adhesive strength was evaluated by the tensile shear strength obtained by dividing the maximum load by the shear cross-sectional area (bonding area). The evaluation criteria are shown below. ◎: 160 kgf / cm ² or more ○ +: 140 kgf / cm ² or more, 160 kgf / cm ²
Less than ○: 120 kgf / cm ² or more, 140 kgf / cm ²
Less than △: 100 kgf / cm ² or more, 120 kgf / cm ²
Less than ×: less than 100 kgf / cm ²

(B) High temperature adhesive strength A sample prepared by the same method as the evaluation test of room temperature adhesive strength according to the above (a) and subjected to thermocompression bonding is pulled by a tensile tester in an atmosphere of 150 ° C. and the maximum load until breaking is applied. The maximum load was measured and the adhesive strength was evaluated by the tensile shear strength obtained by dividing the maximum load by the shearing area (bonding area). The evaluation criteria are shown below. ◎: 80kgf / cm ² or more ○ +: 60kgf / cm ² or more and less than ^{80kgf / cm 2 ○: 40kgf /} cm 2 or more and less than ^{60kgf / cm 2 △: 20kgf /} cm 2 or more, 40kgf / cm ² less than ×: 20kgf </ Cm ²

(C) Blocking resistance: The film forming surfaces of the magnetic steel sheets for the adhesive iron core cut into a size of 20 mm × 20 mm are overlapped with each other, and a pressing force of 250 k is applied.
After pressurizing with gf / cm ² and leaving it in an atmosphere of 50 ° C. for 24 hours, the presence or absence of blocking was examined. The evaluation criteria are shown below. ○: without blocking ×: with blocking

(D) Corrosion resistance A salt spray test was conducted, and the area ratio of red rust after 24 hours was evaluated. The evaluation criteria are shown below. ◎: Red rust occurrence area ratio less than 10% ○: Red rust occurrence area ratio 10% or more, less than 25% △: Red rust occurrence area ratio 25% or more, less than 50% ×: Red rust occurrence area ratio 50% or more

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

[Table 3]

[0045]

[Table 4]

[0046]

[Table 5]

[0047]

[Table 6]

[0048]

[Table 7]

[0049]

[Table 8]

[0050]

[Table 9]

[0051]

[Table 10]

[0052]

As described above, according to the present invention, a stable adhesive strength can be obtained even under the use environment of a motor or a transformer (normal temperature to high temperature), and the blocking resistance and the corrosion resistance are excellent. It is possible to manufacture a magnetic steel sheet for an adhesive iron core having a coating.

[Brief description of drawings]

FIG. 1 is a graph showing the effect of the compounding amount of a latent curing agent with respect to 100 parts by weight of a phenol resin on the high temperature adhesive strength when a phenol resin and a latent curing agent are added together as a curing agent in a coating composition.

FIG. 2 is a drawing showing a temperature rise pattern of thermocompression bonding of an electromagnetic steel sheet for an adhesive iron core performed in an example.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI H02K 15/12 H02K 15/12 A (72) Inventor Masaru Sagiyama 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Inside Nippon Kokan Co., Ltd. (72) Inventor Yoshio Imazaki 33-1 Kanzaki-cho, Amagasaki-shi, Hyogo Kansai Paint Co., Ltd. (72) Inventor Sumio Ezaki 33-1 Kanzaki-cho, Amagasaki-shi, Hyogo Kansai Paint Co., Ltd. (56) Reference Documents JP-A-57-162762 (JP, A) JP-A-5-185029 (JP, A) JP-A-5-237968 (JP, A) JP-A-6-182296 (JP, A) JP-A-6- 60443 (JP, A) JP-A-7-308990 (JP, A) JP-A-7-336969 (JP, A) JP-A-8-24779 (JP, A) JP-B-52-8998 (JP, B2) (58) Fields investigated (Int.Cl. ⁷ , DB name) B32B 1/00-35 / 00 B05D 1/00-7/26 H02K 15/00-15/16

Claims (3)

(57) [Claims] 1. The resin component has an average particle size of 0.05.
A water-based coating composition in which a curing agent is mixed in a ratio of 1 to 40 parts by weight (solid content) with respect to 100 parts by weight of an epoxy resin having a particle size of 2 μm to 1 μm in a dry film thickness on at least one surface of an electromagnetic steel sheet. A method for producing an electromagnetic steel sheet for an adhesive iron core, which is excellent in adhesive strength, corrosion resistance and blocking resistance, characterized by being applied so as to have a thickness of 0 to 12 μm and baked at an ultimate plate temperature of 100 to 300 ° C. 2. The adhesive strength according to claim 1, wherein at least a part of the curing agent is a phenol resin.
A method for producing an electromagnetic steel sheet for an adhesive iron core, which is excellent in corrosion resistance and blocking resistance. 3. The curing agent comprises a phenol resin and a latent curing agent, and the compounding amount of the latent curing agent is 2 to 200 parts by weight based on 100 parts by weight of the phenol resin in terms of solid content. A method for producing an electromagnetic steel sheet for an adhesive iron core, which has excellent adhesive strength, corrosion resistance and blocking resistance according to claim 1.