JP2000173816A - Surface covered electromagnetic steel sheet for sticking and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable surface sticking by making esterification reaction product of acrylic resin and epoxy resin and epoxy resin hardener main components and setting the peak temperature of logarithmic attenuation factor of a covering film in a specified temperature range. SOLUTION: In this manufacturing method of a surface covered electromagnetic steel sheet for sticking, the peak temperature of logarithmic attenuation factor of a covering film is set to 80-200 deg.C, and an adhesive covering film is formed of epoxy resin whose surface is covered with vinyl polymer containing carboxyl group, and epoxy resin hardener. Three-dimensional mesh structure is formed of resin reaction product where acrylic resin and epoxy resin are subjected to esterification reaction. In the vinyl polymer containing carboxyl group, at least one kind of monomer out of alkylester of α,β-ethylenic unsaturated carboxylic acid, hydroxylalkylester and N-hydroxyalkylamide, α,β-ethylenic unsaturated monomer having carboxyl group and styrene based vinyl monomer are subjected to copolymerization in organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface-coated electromagnetic steel sheet for bonding by heating and pressing after punching or shearing, and a method for producing the same.

[0002]

2. Description of the Related Art An electromagnetic steel sheet is usually formed into a unitary iron core by shearing or punching, then laminated, fixed by bolting, caulking, welding or bonding to form a laminated iron core, and then assembled into a winding coil. After that, it is finally assembled into a motor and transformer. However, as a method of fixing the laminated iron core, an insulating film which exhibits adhesiveness by heating and pressing is applied to the surface of the steel sheet in advance, punched or sheared, laminated, and then pressed and heated and fixed. There is also a method using an iron core.

In order to cope with such an iron core manufacturing technique, Japanese Patent Publication No. 55-9815 discloses a treatment liquid obtained by adding a water-soluble styrene-maleic acid copolymer to an acrylic resin emulsion, A technique for forming an incompletely baked adhesive film on the surface has been proposed.

However, the technique disclosed in Japanese Patent Publication No. 55-9815 has a problem that a strong odor is generated during coating and drying. That is, according to this publication,
When an adhesive film in an incompletely baked state is formed on the surface of a steel sheet with a processing solution obtained by adding a water-soluble styrene-maleic acid copolymer to an acrylic resin emulsion, ammonia is used when the styrene-maleic acid copolymer is solubilized. And a water-soluble amine. Thereafter, the ammonia is scattered during the drying by heating and dried. Therefore, a strong ammonia smell is generated during drying, and there is a problem in terms of worker hygiene.

Therefore, Japanese Patent Application Laid-Open No. 06-182296 discloses a technique in which a mixture mainly composed of an acrylic-modified epoxy resin emulsion containing a latent curing agent in advance is uniformly applied to the surface of a steel sheet, and the steel sheet is baked in an incomplete state. Was proposed. According to this, the problem of the odor was solved, the stability of the treatment liquid was improved, the workability was greatly improved, and a surface coated steel sheet for bonding which could be stored for a long time was obtained.

[0006]

However, Japanese Patent Laid-Open Publication No.
The technique described in Japanese Patent No. 182296 has a problem that it is difficult to adhere the entire surface of the unit iron core when laminating the unit iron core and fixing the unit iron core by pressing and heating. In other words, the latent curing agent, which has been previously compounded, chemically reacts with the epoxy resin by heating to cure and adhere the coating, but at the same time as the adhesive coatings applied to the surface of the unit iron core intermingle and fuse by heating, Since the epoxy resin and the epoxy curing agent undergo a curing reaction, the curing reaction partially precedes and the entire surface of the steel sheet may not be adhered. If the entire surface of the steel sheet is not adhered, but partially adhered, the strength of adhesion between the steel sheets will vary, resulting in a part with a weak adhesive strength. There is a problem of causing abnormal vibration.

[0007] The present inventors have disclosed the above-mentioned Japanese Patent Application Laid-Open No. 06-1822.
As a result of intensive studies to solve the problem of JP-A-96, an epoxy resin curing agent was mixed with a resin composition obtained by esterifying an acrylic resin and an epoxy resin, and the peak temperature of the logarithmic decrement of the resin composition was determined. 80 to 200 ° C., the resin composition is melted, and the coatings on the steel sheet surface are intermingled with each other, and thereafter the curing reaction of the resin composition proceeds, whereby the entire surface can be bonded, and furthermore, the adhesive strength can be improved. The inventors have found that it is possible to reduce variations, and have completed the present invention.

[0008]

That is, the gist of the present invention is as follows. (1) An electromagnetically coated electromagnetic coating having an insulating coating on the surface of an electromagnetic steel sheet that exhibits an adhesive ability by applying heat and pressure, wherein the peak temperature of the logarithmic decay rate of the coating is 80 to 200 ° C. steel sheet. (2) The insulating film on the surface of the magnetic steel sheet, which exhibits an adhesive ability by heating and pressing, is made of an esterification reaction product of an acrylic resin and an epoxy resin, and an epoxy resin curing agent. The surface-coated electromagnetic steel sheet for bonding according to (1).

(3) At least one monomer selected from alkyl esters, hydroxyalkyl esters and N-hydroxyalkylamides of α, β-ethylenically unsaturated carboxylic acids and a carboxyl group Using a carboxyl group-containing vinyl polymer composed of an α, β-ethylenically unsaturated monomer and a styrenic vinyl monomer having an acrylic resin as an acrylic resin, and a resin reactant 100 obtained by an esterification reaction with an epoxy resin
The surface coated electromagnetic steel sheet for bonding according to the above item (2), which has a coating mainly composed of parts by weight and 1 to 20 parts by weight of an epoxy resin curing agent. (4) The surface-coated electrical steel sheet for bonding according to the above (3), wherein the weight ratio of the carboxyl group-containing vinyl polymer is 10 to 150 parts by weight with respect to 100 parts by weight of the epoxy resin.

(5) At least one monomer selected from alkyl esters, hydroxyalkyl esters and N-hydroxyalkylamides of α, β-ethylenically unsaturated carboxylic acids and a carboxyl group 100 parts by weight of a resin reactant (solid content) obtained by an esterification reaction of a carboxyl group-containing vinyl polymer composed of an α, β-ethylenically unsaturated monomer having a A method for producing a surface-coated electromagnetic steel sheet for adhesion, comprising applying an aqueous solution mainly containing 1 to 20 parts by weight (in terms of solid content) and 1 to 20 parts by weight (in terms of solid content) of an epoxy resin curing agent. (6) The method for producing a surface-coated electrical steel sheet for bonding according to the above (5), wherein the weight ratio of the carboxyl group-containing vinyl polymer is 10 to 150 parts by weight with respect to 100 parts by weight of the epoxy resin.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments for carrying out the present invention will be described. First, in the coating of the present invention, the peak temperature of the logarithmic decay rate needs to be 80 to 200 ° C. The logarithmic decay rate referred to in the present invention means that the fulcrum of the rigid pendulum is positioned on the coating and the pendulum is vibrated, and the decay rate of the vibration amplitude is expressed in logarithm, and the viscoelastic property of the coating can be evaluated. It is. The logarithmic decay rate can be measured using a commercially available rigid pendulum type viscoelasticity meter (for example, Leo Vibron manufactured by Orientec Co., Ltd.).

When the peak temperature of the logarithmic decay rate is less than 80 ° C. in the coating film of the present invention, the flowability of the coating film at the time of bonding is large, and problems such as resin protrusion during pressurization are likely to occur. If the temperature is higher than 200 ° C., the resin hardly melts at the time of bonding,
This is because the curing reaction of the remaining epoxy groups in the esterification reaction product of the acrylic resin and the epoxy resin proceeds before the coating is melted and partially adheres to each other, thereby increasing the variation in the adhesive strength.

In the present invention, an adhesive film is formed by an epoxy resin whose surface is coated with a carboxyl group-containing vinyl polymer which is an acrylic resin and an epoxy resin curing agent. Since it is separated by vinyl polymer and the epoxy resin is esterified, it is necessary to first melt-mix the epoxy resin and the curing agent to start the curing reaction, and then the esterification By reacting the epoxy resin and the curing agent, the entire surface of the coating is intermingled and melted, and stable adhesive strength with little variation can be obtained.

In the coating of the present invention, a resin reactant obtained by esterification reaction between an acrylic resin and an epoxy resin is used. By proceeding the esterification reaction, epoxy groups in the epoxy resin are consumed, and a three-dimensional network structure is formed. To form The present inventors generally use the glass transition point (Tg) when evaluating the viscoelastic temperature characteristics of an organic resin. However, as in the resin composition of the present invention, a chemical reaction proceeds with a change in temperature and a three-dimensional network is used. The present inventors have found that proper evaluation cannot be made at the glass transition point when a structure is formed, and the present invention has been completed. Although it is desirable that the acrylic resin and the epoxy resin are esterified, even if the resins are only mixed, the epoxy resin and the epoxy resin curing agent do not come into direct contact with each other, and a curing reaction occurs after the coating is melted. If there is no problem.

The carboxyl group-containing vinyl polymer used in the present invention is at least one monomer selected from the group consisting of alkyl esters, hydroxylalkyl esters and N-hydroxyalkylamides of α, β-ethylenically unsaturated carboxylic acids. Α, β-
It can be obtained by copolymerizing an ethylenically unsaturated monomer and a styrene-based vinyl monomer with an ordinary radical polymerization initiator in an organic solvent.

The alkyl esters of α, β-ethylenically unsaturated carboxylic acids used in the present invention include, for example, acrylates (methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-acrylate) Butyl, n-amyl acrylate, n-hexyl acrylate, iso-octyl acrylate, n-octyl acrylate, methoxyethyl acrylate, ethoxyethyl acrylate, 2-ethylbutyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, etc.), methacrylic acid Acid esters (methyl methacrylate, ethyl methacrylate, propyl methacrylate, isobutyl methacrylate, n-butyl methacrylate, n-amyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, stearyl methacrylate, methacrylate N-octyl acrylate, decyl octyl methacrylate, 2-ethylhexyl methacrylate,
Decyl methacrylate).

Examples of the hydroxyalkyl ester of α, β-ethylenically unsaturated carboxylic acid include 2-hydroxyethyl acrylate, hydroxypropyl acrylate,
Examples include 3-hydroxybutyl acrylate, 2,2-bis (hydroxymethyl) ethyl acrylate, 2-hydroxyethyl methacrylate, 3-hydroxybutyl methacrylate, hydroxypropyl methacrylate, and 2,3 dihydroxypropyl methacrylate.

The N, of the α, β-ethylenically unsaturated carboxylic acid
Examples of the hydroxylalkylamide include N-substituted acrylic monomers such as N-methylolacrylamide, N-methylolmethacrylamide, N-butoxymethylacrylamide, and N-butoxymethylmethacrylamide. In the present invention, it is necessary to contain at least one or more monomers selected from the above α, β-ethylenically unsaturated carboxylic acid monomers.

Next, examples of the α, β-ethylenically unsaturated monomer having a carboxyl group include acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and the like.
Crotonic acid, itaconic acid, citraconic acid, cinnamic acid and the like. Examples of the styrene vinyl monomer include styrene, vinyl toluene, t-butylstyrene, and the like.

In the production of the above-mentioned carboxyl group-containing vinyl polymer, although not particularly limited, an α, β-ethylenically unsaturated monomer having a carboxyl group is added in an amount of 10 to 60% by weight based on all monomers. And particularly preferably 15
To 30% by weight, and the copolymerization temperature is 50 to 150%.
C, particularly preferably at 60 to 90C.

The epoxy resin used in the present invention is a liquid at room temperature, preferably a solid, having an average of one or more epoxy groups in a monomer. For example, bisphenol A, F, AD type Phenol novolak type, orthocresol novolak type, phenolic compound modified type, etc., and those having an aromatic ring structure in the monomer are preferable.

In the present invention, it is necessary to chemically bond the carboxyl group-containing vinyl polymer and the epoxy resin by an esterification reaction. The esterification reaction is sufficient under ordinary reaction conditions for reacting an acrylic resin monomer with an epoxy resin monomer. Specifically, it can be obtained by heating and stirring the above carboxyl group-containing vinyl polymer and epoxy resin in an alcoholic solvent at 40 to 100 ° C. in the presence of an esterification catalyst. Although not particularly limited, by performing the esterification reaction in two or more steps, the esterification reaction product can be easily converted into a resin dispersion in an aqueous solution.

As the above esterification catalyst, specifically, trimethylamine, triethylamine, dimethylaminoethanol, diethanolamine, ethylenediamine, diethylenetriamine and the like are preferable. As the alcoholic solvent, for example, ethanol, propanol,
Butanol, amyl alcohol, hexanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, dioxane,
Dimethylformamide, methyl cellosolve acetate and the like.

The aqueous solution in the present invention refers to water alone or a mixture of a hydrophilic organic solvent and water having a water content of 10% by weight or more. Examples of the hydrophilic organic solvent include methanol, Ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, methyl carbitol, ethyl carbitol, methyl carbitol acetate, ethyl carbitol acetate, dioxane, dimethylformamide, dimethyl sulfoxide and the like.

The epoxy resin curing agent used in the present invention can cure an epoxy resin, and usually initiates a curing reaction when heated to a predetermined temperature. Specifically, acid anhydride curing agents (phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, pyromellitic anhydride, pyromellitic anhydride, etc.), aliphatic amines (diethylenetriamine, triethylene Tetramine, polyamide, 2-ethyl-4-methylimidazole, etc.), metaphenylenediamine, dicyandiamide, organic acid dihydrazide, amine imide, ketamine,
Tertiary amine salt, boron trifluoride amine salt, nylon, melamine resin, phenol resin, xylene resin, NBR,
Examples thereof include polysulfide, aniline resin, blocked isocyanate, and acrylic resin. Those exhibiting particularly good characteristics include melamine resins, resole-type phenol resins, blocked isocyanates, and acrylic resins.

The weight ratio of the epoxy resin curing agent must be 1 to 20 parts by weight based on 100 parts by weight of the esterification reaction product of the carboxyl-containing vinyl polymer and the epoxy resin. When the amount of the epoxy resin curing agent is less than 1 part by weight, the heat resistance of the film after bonding tends to be inferior. When the amount exceeds 20 parts by weight, the curing agent tends to be concentrated near the surface of the film after coating and drying, and become cloudy.

Further, as the coating amount better 1 to 15 g / m ^2, especially 3 to 8 g / m ² is preferred. If it is less than 1 g / m ² , the adhesive strength tends to decrease, and if it is 15 g / m ² or more, the space factor tends to be inferior. The baking setting conditions are not particularly limited, but it is preferable to set the plate temperature to 100 to 300 ° C. in a short time in a drying furnace set at 150 to 800 ° C. which is usually performed.

[0028]

EXAMPLES Using the monomers shown in Table 1, carboxyl group-containing vinyl polymers were prepared. Next, the carboxyl group-containing vinyl polymer and the epoxy resin were esterified in dimethylaminoethanol.
Using the epoxy resin curing agent shown therein, treatment solutions shown in Table 1 were prepared. Next, a non-oriented electrical steel sheet (final annealing 0.5 mm, surface roughness Ra) after finish annealing treated by a known method
(Center line average roughness): 0.31 μm)
Was applied with a rubber roll type coating apparatus, and then baked at a plate temperature of 150 ° C. so that the coating amount of the coating was 6 g / m ² . A sample was cut out from this coil, and various coating properties were evaluated. Table 2 shows the results. As is clear from Table 2, it can be seen that in the examples of the present invention, the adhesive strength is strong and that the steel sheets are bonded evenly over the entire surface.

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

According to the present invention, the main component is an esterification reaction product of an acrylic resin and an epoxy resin and an epoxy resin curing agent.
By setting the temperature to 200 ° C., it is possible to bond the entire surface of the steel sheet by heating and pressing, and it is possible to further reduce the variation in the bonding strength.

 ────────────────────────────────────────────────── ─── front page of continued F-term (reference) 4D075 CA13 DA06 DB03 DC19 EB22 EB33 EB45 EB56 4F100 AB03A AH02H AK12B AK12J AK24B AK24J AK25B AK25J AK26B AK26J AK53B AL01B AL06B BA02 CA02B CB03B CB05B EH462 EJ422 GB48 GB51 JA05B JG04B JG06A JK06 JL12B JL13B YY00B 5E041 AA11 BC05 CA02 CA04 HB07 HB14 HB15 NN05 NN18

Claims (6)

[Claims] 1. An adhesive surface, comprising: an insulating coating on a surface of an electromagnetic steel sheet which exhibits an adhesive ability by heating and pressing; and a peak temperature of a logarithmic decay rate of the coating is 80 to 200 ° C. Coated electromagnetic steel sheet. 2. An insulating film on a surface of an electromagnetic steel sheet which exhibits an adhesive ability by heating and pressing, comprising an esterification reaction product of an acrylic resin and an epoxy resin, and an epoxy resin curing agent. Item 2. A surface-coated electromagnetic steel sheet for bonding according to item 1. 3. A carboxyl group and at least one monomer selected from the group consisting of alkyl esters, hydroxyalkyl esters and N-hydroxyalkylamides of α, β-ethylenically unsaturated carboxylic acids, on the surface of a magnetic steel sheet. Using a carboxyl group-containing vinyl polymer composed of an α, β-ethylenically unsaturated monomer and a styrene-based vinyl monomer as an acrylic resin, a resin reactant obtained by an esterification reaction with an epoxy resin, 100 weight The coated surface-coated magnetic steel sheet according to claim 2, comprising a coating mainly composed of 1 part by weight and 1 to 20 parts by weight of an epoxy resin curing agent. 4. The weight ratio of the carboxyl group-containing vinyl polymer to 100 parts by weight of the epoxy resin is from 10 to 150.
The surface-coated electrical steel sheet for bonding according to claim 3, wherein the weight is part by weight. 5. A carboxyl group comprising at least one monomer selected from the group consisting of alkyl esters, hydroxyalkyl esters and N-hydroxyalkylamides of α, β-ethylenically unsaturated carboxylic acids on the surface of a magnetic steel sheet. A carboxyl group-containing vinyl polymer composed of an α, β-ethylenically unsaturated monomer and a styrenic vinyl monomer, and 100 parts by weight of a resin reactant obtained by an esterification reaction with an epoxy resin (in terms of solid content) ) And 1 to 20 parts by weight (in terms of solid content) of an epoxy resin curing agent, and baking the coating in an incomplete state. 6. The weight ratio of the carboxyl group-containing vinyl polymer to 100 parts by weight of the epoxy resin is from 10 to 150.
The method for producing a surface-coated electrical steel sheet for adhesion according to claim 5, wherein the amount is part by weight.