KR100698431B1 - Flat Rolled Magnetic Steel Sheet or Strip Having its Surface Coated for Bonding - Google Patents

Abstract

The present invention provides a surface-coated electronic steel sheet that is adhered to the entire steel sheet even when it is a thin film, the adhesion strength is less reduced, and is bonded by heating and pressing. The adhesive surface-coated electronic steel sheet of the present invention has an insulating film that exerts adhesive performance by heating under pressure on the surface of the electronic steel sheet, and the film has an epoxy resin or epoxy resin modified body having a glass transition point (Tg) of 80 ° C to 150 ° C. And it is characterized in that the mixture of the epoxy resin curing agent and the particulate polymer having a particle diameter of 0.01 to 0.5 ㎛. In addition, the particulate polymer has a Tg of 10 ° C. to 80 ° C. and the particulate polymer is an acrylic polymer.

Surface-coated electronic steel sheets, insulating films, glass transition points, epoxy resins, particulate polymers.

Description

Flat Rolled Magnetic Steel Sheet or Strip Having its Surface Coated for Bonding}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to surface coated electrical steel sheets for bonding by heating and / or pressing after punching or shearing.

In general, when assembling a laminated iron core such as a motor or a transformer using an electronic steel sheet, it is made of unit iron cores by shearing or punching, and then laminated and fixed by bolting, caulking, welding, or bonding. Subsequently, it is followed by a subsequent process such as an assembly process of the winding coil.

By the way, as a method of fixing a laminated iron core, an insulating coating called a coating film, which exhibits adhesiveness by heating and / or pressing, is applied to the surface of the steel sheet, punched and laminated on a unit iron core, and then pressurized heating. Thereby, there is also a method of obtaining a laminated iron core having no rigidity or mechanical distortion and excellent rigidity by making it into a fixing core.

The adhesive film requires a function as an adhesive for fixing the core and a function as an insulating film formed on the surface of the electrical steel sheet. However, there are many cases in which the adhesive film is incompatible with the properties required as the adhesive and the property required as the insulating film. Technology is required. For example, as the adhesive, it is considered that a soft one is preferred in order to easily achieve a uniform adhesive state. On the other hand, when the punching process is performed on the unit iron core, the insulating film is preferably a hard coating so as not to cause scratches on the surface. In addition, as adhesive, it is good to have high wettability on the surface of an adhesive film in order to bond unit iron cores firmly, but as an insulating film, the wettability is good in order to maintain corrosion resistance.

In order to satisfy such opposing properties, Japanese Patent Laid-Open Publication No. Hei 6-182296 uniformly applies a mixed liquid containing an acrylic modified epoxy resin emulsion containing a latent curing agent on the surface of a steel sheet in advance to bake in an incomplete state. The technique to which it is proposed is obtained, The surface coating steel sheet for adhesion | attachment which the stability of a process liquid is favorable and coating | coating workability is favorable and long-term storage is obtained was obtained.

However, the technique described in Japanese Unexamined Patent Publication No. Hei 6-182296 has a problem in that it is difficult to adhere the entire surface of the unit iron core when the unit iron cores are laminated, pressurized and fixed. That is, the latent curing agent formulated in advance is to chemically react with the epoxy resin by heating to cure and bond the coating, but the adhesive coatings applied to the surface of the unit core by heating are mixed with each other, melted, and at the same time, the epoxy resin and epoxy Since the hardening | curing agent hardens | cures reaction, the hardening reaction may precede partially and the whole steel plate may not adhere | attach. In the state where the entire surface of the steel sheet is not fixed but partially fixed, the adhesion strength between the steel sheets is unbalanced, and the weak adhesive strength is generated. Therefore, the core is decomposed during manufacturing or the motor may cause abnormal vibration during rotation. There was a problem.

Therefore, Japanese Patent Application Laid-Open No. 10-343276 discloses a technique in which an epoxy resin curing agent is mixed with a resin composition obtained by esterifying an acrylic resin and an epoxy resin, and the peak temperature of the logarithmic susceptibility of the resin composition is 80 to 200 ° C. It is. After the adhesive films on the surface of the steel sheet were melted and mixed with each other by this technique, curing of the resin composition proceeded, thereby enabling full-surface adhesion.

In recent years, with increasing interest in global environmental issues, high efficiency for motors and transformers has been highly demanded, and in order to improve the efficiency of motors and transformers, improvement of the spot ratio has also been required for electronic steel sheets. Also, it is required to reduce the film thickness to 3 µm or less. However, in the technique described in Japanese Patent Application Laid-open No. Hei 10-343276, it has been found that the problem that it is difficult to adhere the entire surface of the unit iron core is still not solved when the thickness of the adhesive film is reduced.

That is, in general, an electronic steel sheet coated with an adhesive film has a thickness of 3 to 8 µm, while an organic-inorganic mixed insulating film coated on the non-oriented electrical steel sheet maintains a film thickness of about 1 to 2 µm. It is common to apply thick. The reason for this is that when the film thickness is thin, even a subtle surface irregularities such as rolling scratches generated when the steel sheet is rolled, a portion which does not come into contact with the surface is generated, and a portion to be bonded and a portion that is not bonded are generated.

That is, although the surface roughness of the steel plate surface is naturally present in the setting of the rolling mill, the difference (Rmax) between the highest point and the lowest point in the predetermined measurement range is about 1 to 5 µm, and therefore, it is necessary to apply the coating thickness more than this difference. In particular, a phenomenon that becomes remarkable when the film thickness is thin is that when the adhesive strength is measured using a single plate, the adhesive strength is relatively secured, but when the laminated iron core is used, the phenomenon in which the strength in the direction in which the laminated surface is pushed open is lowered. have. As a result, even in the adhesive strength test using a single plate, even if the level is not a problem, when the laminated iron core is used, a gap occurs in the laminated surface, or in severe cases, the laminated iron core is decomposed due to the impact during handling.

Moreover, when apply | coating a heat resistant adhesive film to the electrical steel plate with which the normal organic-inorganic mixed insulating film and the inorganic insulating film were applied, peeling will generate | occur | produce between a normal insulating film and an electrical steel sheet, and adhesive strength will fall. It turns out that problems sometimes arise.

As a technique for reducing the internal stress of an epoxy resin, various methods have been disclosed and suggested so far, but, for example, Japanese Patent Laid-Open No. 62-50361 discloses microparticles of a polymer whose glass transition temperature does not reach room temperature. There exists a technique using the epoxy resin composition characterized by the above-mentioned. Since the adhesive coating is used as an iron core of a motor or a transformer, heat resistance against temperature rise due to generation of joule heat is required. In the invention described in the above publication, the internal stress can be reduced after maintaining the heat resistance.

However, the technique disclosed in Japanese Patent Application Laid-Open No. 62-50361 is a very useful technique with respect to the effect of lowering the internal stress of the epoxy resin, but it is an adhesive that requires the characteristics of both the adhesive and the insulating film of the electrical steel sheet. Since the coating is not considered and it is not a technique that satisfies various characteristics such as corrosion resistance and blocking properties that the adhesive coating requires, there are many problems as an adhesive coating.

The present inventors have found that the problem of thinning these film thicknesses in various experiments is that the so-called internal stress caused by applying the adhesive film is large, and that the problem can be solved by lowering the internal stress of the adhesive film. .

The present inventors have found a method necessary for reducing the internal stress of the adhesive film, improving the adhesive strength in the direction of pushing open the adhesive surface of the adhesive film at the time of thin film, and forming the adhesive film after carrying out the usual insulating film. The adhesive film which can prevent the fall of the adhesive strength in the case was found, and this invention was completed.

That is, this invention makes the following structure a summary.

(1) An electrical steel sheet having an insulating film that exhibits adhesive performance by heating and / or reduced pressure on its surface, wherein the film has an epoxy resin or epoxy resin modified body and epoxy having a glass transition point (Tg) of 80 ° C to 150 ° C. A surface-coated electronic steel sheet for bonding, characterized in that a mixture of a resin curing agent and a particulate polymer having a particle diameter of 0.01 µm to 0.5 µm is dispersed.

(2) The surface-coated electrical steel sheet for adhesion according to (1) above, wherein the particulate polymer has a Tg of 10 ° C to 80 ° C.

(3) The surface-coated electrical steel sheet for adhesion according to (1), wherein the particulate polymer is an acrylic resin.

(4) The surface-coated electronic steel sheet for adhesion according to (1), wherein 1 to 30 parts by weight of the particulate polymer is contained with respect to 100 parts by weight of the epoxy resin.

(5) The surface-coated electronic steel sheet for adhesion according to (1), wherein the epoxy resin is modified by an esterification reaction with an acrylic resin in advance.

(6) Epoxy resin or an epoxy resin modified body, an epoxy resin curing agent, and a particulate form in the electrical steel sheet according to any one of (1) to (5), wherein an organic inorganic mixed insulating film or an inorganic insulating film is formed on the surface. A surface-coated electronic steel sheet for adhesion, wherein an insulating film having adhesion is formed in which a polymer is dispersed.

FIG. 1 shows that a sample plate punched into a shape of 2 cm × 3 cm is heated and pressurized at 200 ° C. × 10 kgf / cm 2 × 30 minutes, followed by a pressure division test at room temperature, and each sample is collected and broken. It is a photograph of the state which observed the surface state with the scanning electron microscope about the adhesive surface. 1A is a photograph of a broken state of a conventional adhesive surface, and FIG. 1B is a photograph of a broken state of an adhesive surface according to the present invention.

Fig. 2 shows the concept of the peel test method which has been used as one of the methods for measuring the adhesive strength and the conceptual diagram of the pressure division test method newly devised in carrying out the present invention. All of these methods are peel strength measurement methods for pulling down a steel sheet bonded by an adhesive or an adhesive film. However, in the peel test method, since the steel sheet is greatly deformed, the influence of the properties of the steel sheet itself is very large. By laminating and fixing every steel plate, the influence of a steel plate can be suppressed to the minimum, and the characteristic of an adhesive member can be evaluated in detail.

Best Mode for Carrying Out the Invention

EMBODIMENT OF THE INVENTION Hereinafter, the specific form which implements this invention is demonstrated.

In the film of this invention, it is necessary to disperse | distribute the specific organic resin particle of the range which is 0.01-0.5 micrometer of epoxy resin hardeners and particle size in an epoxy resin or an epoxy resin modified body.

The epoxy resin used in the present invention is a glass transition point (Tg) after curing in the range of 80 ° C to 150 ° C, and is a liquid, preferably a solid at room temperature before the curing reaction, and an average of one in monomers. Although it will not specifically limit, if it has the above epoxy group, It is preferable that epoxy equivalent is 100-5000.

Specifically, there are bisphenol A, F, AD type, phenol novolak type, orthocresol novolak type, phenol compound modified type, and the like, and those having an aromatic ring structure in the monomer are preferable.

In the film of this invention, not only an epoxy resin but the modified body of an epoxy resin can also be used. Although it does not specifically limit about the method of making an epoxy resin into a modified body, A specific substituent is used for a main chain, or various compounds are couple | bonded with the epoxy group of the epoxy resin terminal, or the hydroxyl group of a side chain. In particular, as the adhesive coating, it is preferable that the curing reaction of the epoxy resin proceeds after the resin component is melted. As the modified body, an acrylic modified epoxy resin obtained by esterifying an acrylic resin to an epoxy resin is preferable.

As acrylic resin used for the said epoxy resin modified body, the polymer of the polymerizable monomer containing a carboxyl group-containing vinyl polymer is preferable. Specifically, α, β-ethylenically unsaturated monomers and styrene having one monomer selected from alkyl esters, hydroxylalkyl esters of α, β-ethylenically unsaturated carboxylic acids and N-hydroxyalkylamides and carboxyl groups It is a system containing a vinyl monomer, and these mixtures can be obtained by copolymerizing in a organic solvent using a normal radical polymerization initiator.

As alkyl ester of the (alpha), (beta)-ethylenically unsaturated carboxylic acid used by this invention, acrylic ester (for example, methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n butyl acrylate, n amyl acrylate, acrylic acid is mentioned, for example. nhexyl, isooctyl acrylate, n octyl acrylate, methoxy ethyl acrylate, ethoxy ethyl acrylate, 2 ethyl butyl acrylate, 2 ethyl hexyl acrylate, decyl acrylate, etc., methacrylic acid esters (methyl methacrylate, methacrylic acid) Ethyl, propyl methacrylate, isobutyl methacrylate, n butyl methacrylate, n amyl methacrylate, n hexyl methacrylate, lauryl methacrylate, stearyl methacrylate, n octyl methacrylate, methacrylate Decyl octyl, 2 ethylhexyl methacrylate, decyl methacrylate, and the like.

As a hydroxyalkyl ester of (alpha), (beta)-ethylenically unsaturated carboxylic acid, For example, 2 hydroxyethyl acrylate, hydroxypropyl acrylate, 3 hydroxybutyl acrylate, 2,2 bis (hydroxymethyl) ethyl, Methacrylic acid 2 hydroxyethyl, methacrylic acid 3 hydroxybutyl, methacrylic acid hydroxypropyl, methacrylic acid 2,3 dihydroxypropyl and the like.

As N-hydroxyalkylamide of (alpha), (beta)-ethylenically unsaturated carboxylic acid, it is N-methylol acrylamide, N-methylol methacrylamide, N-butoxymethyl acrylamide, N-butoxymethyl, for example. N substituted acrylic monomers such as methacrylamide and the like.

In this invention, it is preferable to contain 1 or more types of monomers chosen from the said (alpha), (beta)-ethylenically unsaturated carboxylic monomer.

Subsequently, examples of the α, β-ethylenically unsaturated monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, and the like. .

As a styrene-type vinyl monomer, styrene, vinyltoluene, t-butyl styrene, etc. are mentioned, for example.

Although it does not specifically limit in the manufacturing method of the said carboxyl group-containing vinyl polymer, The (alpha), (beta)-ethylenically unsaturated monomer which has a carboxyl group is 10-60 mass% with respect to all monomers, Especially preferably, it is 15-30 mass%, and copolymerization is carried out. As temperature, it is good to carry out at 50-150 degreeC, Especially preferably, it is 60-90 degreeC.

The reason why the Tg of the epoxy resin or the epoxy resin modified product after curing is limited to 80 ° C. to 150 ° C. is lower than 80 ° C. because the heat resistance after adhesion is poor, and heat generation at the time of driving a motor or transformer cannot be tolerated. This is because when the film is exceeded, the coating becomes too hard and the adhesive strength is lowered, or the deterioration proceeds excessively due to vibration or the like when used as a motor or a transformer. Especially preferably, it is the range of 90-120 degreeC, More preferably, it is 110-120 degreeC. In this range, the particulate polymer is dispersed in the epoxy resin, thereby reducing the internal stress.

Subsequently, the particulate polymer used in the present invention has a particle size in the range of 0.01 μm to 0.5 μm, and can be used in the epoxy resin in a dispersed state stably. As a kind of particulate polymer which can be used by this invention, acrylic resin, vinyl acetate, polyester, polyurethane, polyethylene, polypropylene, polycarbonate, etc. are preferable.

Specific examples of acrylic resins include acrylic acid esters (methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n butyl acrylate, n amyl acrylate, n hexyl acrylate, isooctyl acrylate, n octyl acrylate, methoxyethyl acrylate, and acrylic acid. Methoxyethyl, 2ethylbutyl acrylate, 2ethylhexyl acrylate, decyl acrylate, etc., methacrylic acid esters (methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate) N amyl methacrylate, n hexyl methacrylate, lauryl methacrylate, stearyl methacrylate, n octyl methacrylate, decyl octyl methacrylate, 2 ethylhexyl methacrylate, decyl methacrylate, etc.), 2 hydroxyethyl acrylate, hydroxypropyl acrylate, 3 hydroxybutyl acrylate, 2,2 bis (hydroxymethyl) ethyl acrylate, 2 hydroxyethyl methacrylate, 3 hydroxy methacrylate , Methacrylic acid hydroxypropyl, methacrylic acid 2,3 dihydroxypropyl, N-methylol acrylamide, N-methylol methacrylamide, N-butoxymethyl acrylamide, N-butoxymethyl methacrylamide 1 to 2 steps of monomers such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, styrene, vinyltoluene, t-butylstyrene, etc. By emulsion polymerization.

Examples of vinyl acetate include vinyl acetate, vinyl acetate-beova copolymers, vinyl acetate-ethylene copolymers, and the like.

As a polyurethane, what has a urethane bond in a monomer, The thing obtained by the chemical reaction of an isocyanate compound, a polyol, or a polyether can be used mainly, Tolylene diisocyanate, diphenylmethane 4, 4- diisocyanate, hexamethylene diisocyanate Isocyanate compounds such as trimethylpropane 1-methyl2-isocyano4-carbamate, polymethylenepolyphenylisocyanate, methaxylylene diisocyanate and the like, polyols such as polyethylene glycol, polypropylene glycol, polyethertriol, and the like, It is a combination of polyethers.

As polyester, the general thing which reacted dibasic acid and dihydric alcohol can be used, Specifically, as dibasic acid, maleic anhydride, fumaric acid, adipic acid, a phthalic anhydride, isophthalic acid, a dihydric alcohol is ethylene glycol, propylene glycol, Diethylene glycol, 1, 3- butylene glycol, dipropylene glycol, neopentyl glycol, bisphenol dioxyethyl ether, etc. can be used.

The particulate polymer used in the present invention needs to have a particle size in the range of 0.01 μm to 0.5 μm. This is because when the particle diameter is less than 0.01 µm, the effect of improving the adhesive strength is not obtained even when the film thickness of the present invention is thin. When the particle diameter is larger than 0.5 µm, the adhesion strength is inhibited by lowering the melting of the epoxy resins.

The inventors of the present invention have a more important function in the case of dispersing the particulate polymer in the adhesive film, and by using a very narrow range of the particulate polymer of 0.01 μm to 0.5 μm to satisfy various characteristics required for the adhesive film. Found that it can.

The reason for this is that in the adhesive film, the film thickness is very thin, even if it is several micrometers, even if it is thick, it is very thin. Therefore, in order to uniformly disperse the fine particles in the epoxy resin, the size is naturally limited, for example, the fine particles having a particle size larger than the film thickness. Is added, it is assumed that the effect of the present invention cannot be obtained because the "island-sea structure" cannot be formed by the region of only the constituents of the fine particles appearing at the time of application drying. Therefore, the particle diameter of the particulate polymer from which the effect is obtained is limited to a very narrow range, and in the results examined by the present inventors, it is preferably 0.05 µm or more, more preferably 0.1 µm or more, particularly preferably 0.2 µm to 0.4 µm to be.

It is preferable that the particulate polymer used in the present invention has a glass transition point of 10 ° C to 80 ° C. If the glass transition point is less than 10 ° C, scratches tend to occur in the film during slit work or punching, and if the glass transition point is more than 80 ° C, the film may be whitened. More preferable glass transition points are 25 degreeC or more, 35 degreeC or more, 45 degreeC or more, 55 degreeC or more about the minimum, and 70 degrees C or less and 65 degrees C or less about the upper limit.

The method of dispersing the particulate polymer of the present invention in an epoxy resin is not particularly limited, and acrylics may be obtained by mechanically mixing the resins, mixing each of them into an emulsion, or emulsion polymerization in an acrylic modified epoxy resin solution. The resin may be made into a particulate polymer.

Although a spherical form is generally preferable as a form of a particulate polymer, what is called a hybrid type | mold which differs in composition from a mold release, such as a hollow form, an egg form, etc. in the inside and an outer peripheral side may be sufficient. Moreover, depending on compatibility with an epoxy resin, it may not show a clear external appearance. Considering the possibility of excessively partial pressure applied during processing such as slits, the higher the interfacial adhesion between the epoxy resin and the particulate polymer, the better the processability, so that it does not matter even if the appearance is not obvious.

As addition amount of a particulate-form polymer, 1-30 weight part is suitable with respect to 100 weight part of epoxy resins. It is because when it is less than 1 weight part, the effect of this invention will not appear, and when it exceeds 30 weight part, aggregation and precipitation of particulate polymers will arise easily, and trouble will arise in handling.

The epoxy resin hardening | curing agent used by this invention is what can harden | cure an epoxy resin, and usually starts hardening reaction by heating at predetermined temperature. Specifically, acid anhydride type curing agents (phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, pyromellitic anhydride, pyromellitic anhydride, etc.), aliphatic amines (diethylenetriamine, triethylenetetramine, polyamide, 2 ethyl 4 methylimidazole, etc.), metaphenylenediamine, dicyandiamide, organic acid dihydrazide, amineimide, ketamine, tertiary amine salt, boron trifluoride amine salt, nylon, melamine resin, phenol resin, Xylene resin, NBR, polysulfide, aniline resin, block isocyanate, acrylic resin, etc. are mentioned. Particularly favorable properties are melamine resin, resol type phenol resin, block isocyanate, acrylic resin and the like.

The weight ratio of the epoxy resin curing agent is preferably 1 to 30 parts by weight based on 100 parts by weight of the esterification reaction product with the epoxy resin. When the epoxy resin curing agent is less than 1 part by weight, the heat resistance of the film after adhesion tends to be poor. When the epoxy resin curing agent is more than 30 parts by weight, the curing agent tends to be concentrated in the vicinity of the surface of the coating and become cloudy after application drying.

Moreover, as a film amount, 1-6 g / m <2> is preferable and 1-3 g / m <2> is especially preferable. It is because there exists a tendency for adhesive strength to fall that it is less than 1 g / m <2>, and when it exceeds 6 g / m <2>, a spot ratio will tend to become inferior.

Subsequently, baking setting conditions at the time of forming a film in an electronic steel plate are not specifically limited, It can be 100-300 degreeC at plate temperature in a short time in the drying furnace set to 150-800 degreeC as usual.

Although the mechanism of the present invention is considered to be due to the reduction of internal stress, it is not disclosed in detail, and although the glass transition point below room temperature is effective in the technique disclosed in Japanese Patent Laid-Open No. 62-50361, in the adhesive coating, it is in the form of fine particles. The glass transition point of the polymer may rather be in the range of 10 ° C. to 80 ° C., and the reason why the particle diameter of the particulate polymer greatly affects the adhesive strength is not known in detail. However, in the case of the adhesive film, the thermal expansion coefficient is very small and the epoxy resin layer is formed very thinly on the surface of the steel sheet having high rigidity, and the internal stress reduction mechanism of the general organic resin has different factors. It is assumed to work.

BRIEF DESCRIPTION OF THE DRAWINGS The sample (No.2) which adhere | attached the surface-coated steel plate for adhesion | coating and baking which apply | coated-baked the resin composition based on this invention on 200 degreeC x 10 kgf / cm <2> conditions for 30 minutes, and the sample based on a prior art example The bonding part fracture surface of the sample (No. 1) bonded to each other was observed with a scanning electron microscope. Sample based on the conventional example In FIG. 1A, the broken part showed the smooth surface, and it can be said that the propagation of the crack generate | occur | produced rapidly.

On the other hand, in the sample based on this invention, fine unevenness | corrugation generate | occur | produced in the broken part in FIG. 1B, and the propagation path | route of a crack is entangled.

From these observation results, in the case of the resin composition based on this invention, the so-called "sea-sea structure" by which the acrylic resin microparticles were uniformly dispersed in the epoxy resin continuous phase is formed, the propagation of a crack is delayed, and therefore adhesive strength is improved. It is also estimated to have improved.

In addition, the shear bond strength and the adhesive strength of the pressure division test performed in the present invention show different behavior. In other words, in the shear strength test, the force in the vertical direction does not act on the adhesive surface of the steel sheet, whereas in the pressure division test, there is a component that acts in the vertical direction on the adhesive surface, and of course, the peeling behavior of the adhesive film changes. In consideration of the electromagnetic force acting on the laminated iron core, such as a motor, the pressure division test is considered to be the strength required for the actual laminated iron core.

Usually, as a measuring method of the intensity | strength of a pressurization division direction, a peel strength measuring method is common. By the way, as a result of the present inventor's examination, when peeling strength is measured using an electronic steel plate, since the bending generate | occur | produces in a sample, it is difficult to peel peeled adhered samples smoothly, and an imbalance becomes very large and difficult to measure.

Moreover, in the method of manufacturing a thin steel plate for peel strength measurement, since the surface state differs from the electrical steel plate which adds various steel components, there exists a possibility that it will become a different behavior from an actual laminated iron core.

Therefore, the present inventors have found that the adhesive strength in the pressure-dividing direction can be measured by injecting a wedge into the iron core sample laminated by lamination as a method of measuring the adhesive strength in the pressure-dividing direction. In Japanese Patent Laid-Open No. 62-50361, the peel test method (ASTM D1876) is used as a method for measuring the adhesive strength. However, in the present invention, a pressure-dividing test method was devised for use in electronic steel sheets and compared with the conventional example. 2 shows a peel test method and a pressure division test method measured in the present invention, which are conventional methods.

The coil of the non-oriented electrical steel sheet (plate thickness 0.5mm, silicon amount 0.5%) after finishing annealing processed by the well-known method was supplied as a test material as it is, without apply | coating a normal insulating film. Next, the epoxy resin emulsion shown in following Table 1, an epoxy resin hardening | curing agent, and the particulate-form polymer shown in following Table 2 were mixed in order, and the process liquid shown in following Table 3 was produced. After apply | coating each process liquid with the application | coating device of a rubber roll system, it baked at the plate temperature of 160 degreeC so that the application amount of a film might be the quantity described in the table.

Samples were taken from this coil to evaluate various properties of the coating. The results are shown in Table 4 below. Next, Table 5 shows the case where the coil baked by apply | coating and baking the organic-inorganic mixed film of magnesium chromium-acrylate resin system apply | coated to a normal electrical steel sheet to 1 g / m <2> was supplied as a test material. In addition, in order to convert the coating amount into a film thickness, it is necessary to change the conversion formula, for example, when the coating amount is large and when the coating amount is small or when the surface roughness of the steel sheet is different, but when applied in the present invention, 1 g / m 2 From about 0.6 μm to 1 μm.

Regarding the adhesive strength in the direction in which the adhesive surface is pushed open, after depositing 40 samples extracted in a size of 2 cm x 3 cm from a coil coated with a predetermined amount of each solution, it is fixed with an exclusive jig and fixed at 200 ° C. After manufacturing the laminated iron core bonded by heat press bonding for 10 * 10 kgf / cm <2> * 30 minutes, the wedge-shaped indenter was pressed to the center part of the laminated surface, and the load when the laminated iron core was isolate | separated was measured.

*: Since epoxy 3 modified | denatured acrylic resin functions as a hardening | curing agent, hardening | curing agent was not added.

*: Explanation of symbols in Tables 1 and 2

BPA: bisphenol A type epoxy, NR: novolak type epoxy, PR: phenol resol type curing agent, AR: amino resin curing agent, EA: ethyl acrylate, MMA: methyl methacrylate, St: styrene, BA: butyl acrylate, PVA: Vinyl acetate, PA: polyethylene, PU: polyurethane, HPMA: methacrylate hydroxypropyl, MA: acrylic acid, EHMA: 2-ethylhexyl methacrylate

*: Parts in the table are parts by weight in terms of resin solids.

(Note) a: Shear adhesive force is measured at normal temperature after crimping | bonding for 60 second at the pressure of 10 kg / cm <2>, temperature 200 degreeC.

b: The adhesive strength is measured in the state heated at 150 degreeC after adhere | attaching on the said a conditions.

c: 40 sheets of samples sheared at 2 cm × 3 cm were laminated, adhered under conditions of 200 ° C. × 10 kgf / cm 2 × 30 minutes, and then a wedge (tip 7 °) was pressed into the center of the laminated surface, Measure the maximum load at that time.

d: After pressing at 20 kg / cm 2 for 72 hours at room temperature, the degree of adhesion was evaluated. ◎ What was not adhered at all, 약간 which was slightly adhered, △ which was adhered, but which did not require a force to peel by hand, △, which required a force to peel by hand were called ×, and ○ was said to pass.

According to the present invention, even if a thin coating is applied by using a mixture of an epoxy resin or an epoxy resin modified body having a glass transition point (Tg) of 80 ° C to 150 ° C, an epoxy resin curing agent and a particulate polymer having a particle size of 0.01 to 0.5 µm The fall of adhesive strength can be reduced, the adhesive strength in the direction to push an adhesive surface can also be fully ensured, and also the adhesive strength fall can be reduced also when apply | coating on a normal insulating film.

Claims (6)

Epoxy resin or epoxy resin modified body and epoxy which have an insulating film which exerts the adhesive ability by heating, pressurization, or both on the surface of an electrical steel plate, and the said film has a glass transition point (Tg) of 80 degreeC-150 degreeC A surface-coated electronic steel sheet for bonding, characterized in that a mixture of a resin curing agent and a particulate polymer having a particle diameter of 0.01 µm to 0.5 µm is dispersed. The surface-coated electronic steel sheet for bonding according to claim 1, wherein the particulate polymer has a Tg of 10 ° C to 80 ° C. The adhesive coated surface steel sheet according to claim 1, wherein the particulate polymer is an acrylic resin. The adhesive coated surface steel sheet according to claim 1, wherein 1 to 30 parts by weight of the particulate polymer is contained per 100 parts by weight of the epoxy resin. The adhesive coated surface steel sheet according to claim 1, wherein the epoxy resin is modified in advance by esterification with an acrylic resin. The electronic steel sheet according to any one of claims 1 to 5, wherein an epoxy resin or an epoxy resin modified body, an epoxy resin curing agent, and a particulate polymer are dispersed in an electronic steel sheet having an organic inorganic mixed insulating film or an inorganic insulating film formed on a surface thereof. The insulating coated steel sheet for adhesion | attachment was formed, The insulating coating film which has an adhesive ability was formed.

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