阅读说明：本技术 一种电工钢用自粘接性绝缘涂层液 (Self-adhesive insulating coating liquid for electrical steel ) 是由 唐永明 周雨 周真菊 于 2020-03-19 设计创作，主要内容包括：本发明公开了一种电工钢用自粘接性绝缘涂层液,其各组分的重量百分比为：环氧树脂15～60％、马来酸酐聚合物1～20％、助溶剂1％～20％、乳化剂1％～40％、余量为去离子水。本发明的自粘接性绝缘涂层液应用于制备电工钢表面绝缘涂层,经加压加温后即可实现电工钢片之间的粘接叠装,无需进行焊接、栓接或铆接；而且本发明的自粘接性绝缘涂层液为乳液,不含不溶性固体微粒,储存稳定性好。(The invention discloses a self-adhesive insulating coating liquid for electrical steel, which comprises the following components in percentage by weight: 15-60% of epoxy resin, 1-20% of maleic anhydride polymer, 1-20% of cosolvent, 1-40% of emulsifier and the balance of deionized water. The self-adhesive insulating coating liquid is applied to preparing an insulating coating on the surface of electrical steel, and can realize the adhesive lamination between electrical steel sheets after pressurization and heating without welding, bolting or riveting; the self-adhesive insulating coating liquid is emulsion, does not contain insoluble solid particles and has good storage stability.)

1. A self-adhesive insulating coating liquid for electrical steel is characterized in that the coating liquid comprises the following components in percentage by weight: 15-60% of epoxy resin, 1-20% of maleic anhydride polymer, 1-20% of cosolvent, 1-40% of emulsifier and the balance of deionized water.

2. The self-adhesive insulating coating liquid for electrical steel according to claim 1, characterized in that: the epoxy resin is one or more of bisphenol A type glycidyl ether, bisphenol F type glycidyl ether, bisphenol S type glycidyl ether, polyphenol type glycidyl ether and aliphatic glycidyl ether.

3. The self-adhesive insulating coating liquid for electrical steel according to claim 1 or claim 2, characterized in that: the epoxy value of the epoxy resin is 0.06-0.51.

4. The self-adhesive insulating coating liquid for electrical steel according to claim 1, characterized in that: the maleic anhydride polymer has the following structure:

wherein R is a monomer copolymerized with maleic anhydride, and comprises one or more of acrylic acid, acrylate, styrene, methyl vinyl ether and vinyl acetate.

5. The self-adhesive insulation coating liquid for electrical steel according to claim 1 or claim 4, characterized in that: the m value of the maleic anhydride polymer ranges from 4 to 20, and the n value ranges from 0 to 20.

6. The self-adhesive insulating coating liquid for electrical steel according to claim 1, characterized in that: the cosolvent has the following structure:

wherein p is 1 or 2, and the value range of q is 0-4.

7. The self-adhesive insulating coating liquid for electrical steel according to claim 1, characterized in that: the anionic emulsifier is sodium (potassium) alkylbenzene sulfonate.

8. The self-adhesive insulating coating liquid for electrical steel according to claim 1, characterized in that: the nonionic polyether nonionic emulsifier has the following structure:

wherein R' is a polyether initiator group and comprises one or more of hydrogen group, fatty alcohol group, alkylphenol group, castor oil group, fatty acid group, fatty amine group, sorbitol ester group and fatty acid ester group, the s value range is 4-30, and the t value range is 0-20.

Technical Field

The invention relates to a self-adhesive insulating coating liquid for electrical steel.

Background

An electrical steel sheet is mainly used for manufacturing an iron core of a motor, and in order to reduce eddy current loss of the iron core, an electrical silicon steel sheet needs to be subjected to insulation treatment before use, and a common method is to coat a layer of high-impedance insulating coating on the surface of the electrical silicon steel sheet so as to enable the silicon steel sheet to have higher interlayer resistivity and minimize interlayer power loss, and meanwhile, the surface coating of the silicon steel sheet is required to have good heat resistance and corrosion resistance and can work in a high-temperature and corrosive environment. In addition, since the electrical silicon steel sheet is subjected to processes such as slitting and punching before use, the coating layer is required to have high adhesion and not to be easily peeled off in punching and shearing or bending.

A representative variety of electrical steel sheet insulating coatings are semi-organic coatings. The coating liquid of the coating consists of chromate or phosphate, organic resin, other inorganic salt and the like, and the formed coating has good adhesive force, insulating property and impact resistance and is widely applied to the insulating coating of electrical steel. However, in manufacturing the core, electrical steel sheets need to be stacked together. For the semi-inorganic coating, the electrical steel sheets are stacked by welding, bolting or riveting. Welding, bolting or riveting inevitably damages the insulating coating, causing short-circuiting of the core edges, degrading insulation and corrosion resistance, and these stacking methods are not suitable for precision micro-motors. In contrast, if the insulating coating of the electrical steel has self-adhesion, the self-adhesion coating can be coated in the production process of the electrical steel strip, and when the iron core is manufactured, the electrical steel strips coated with the self-adhesion coating are only required to be laminated together, and then the bonding and stacking between the electrical steel strips can be realized by heating and pressurizing. This approach does not destroy the coating, has no effect on the insulating and corrosion protective properties of the coating, and is therefore very attractive.

Chinese patent CN 1690199 discloses a composition and a preparation method of an electrical steel self-adhesive coating liquid, which is characterized in that a resin component is an epoxy resin emulsion with the epoxy equivalent of 200-4000, 0.07-17% of dicyandiamide is added as a latent curing agent, and the coating liquid is coated on the surface of the electrical steel to form a self-adhesive coating after being baked in the presence of a small amount of curing accelerator; chinese patent CN 105131750 discloses an environment-friendly self-adhesive coating for electrical steel, which is characterized in that 15-50% of water-soluble acrylic resin and 30-70% of water-based epoxy resin are taken as main resin components, 1-10% of dicyandiamide is added as a curing agent, and other auxiliary agents are added for obtaining a suspension type coating liquid after sanding; chinese patent CN 110099980 discloses a non-oriented electrical steel sheet adhesive coating composition, which is characterized in that the coating liquid contains 40-99% of a first component containing water-soluble resin and 1-60% of a second component containing complex metal phosphate, wherein the water-soluble resin is selected from more than one of epoxy resin, siloxane-based resin, acrylic resin, phenolic resin, styrene resin, vinyl resin and polyurethane resin. Chinese patent CN 110382223 discloses a polymer composition consisting of a high molecular weight acrylate-based copolymer and a cross-linking agent as a resin component of an electrical steel coating liquid; chinese patent CN101040022 discloses a heat-resistant adhesive coating liquid, which is characterized in that the resin component is one or more of epoxy resin, acrylic resin, phenol resin, acryl-modified epoxy resin emulsion, incompletely cured resin containing a latent curing agent, and siloxane polymer, and the suspension coating liquid is formed after glass frit is added.

The common characteristics of the coating liquids are that a suspension containing solid particles is formed, the stability of the coating liquid is poor, precipitates are easy to generate in the storage process, the use of the coating liquid is influenced, the coating is easy to cause non-uniformity due to poor compatibility of the solid particles and other components of the coating liquid, and the peeling strength and the shearing strength of the coating are reduced.

Disclosure of Invention

The invention aims to provide a self-adhesive insulating coating liquid for electrical steel, which is coated on the surface of the electrical steel, is baked and dried for a short time, and then is in a dormant state, and after the electrical steel sheets with the coating are stacked, the coating can be activated only by heating and pressurizing, so that the self-adhesion of the electrical steel sheets is realized, and the damage of stacking modes such as welding, bolting or riveting to the insulating coating is avoided; the coating liquid is in an emulsion type and does not contain solid particles, and a coating formed by using the coating liquid has the characteristics of uniform coating, good insulativity, high peel strength and high shear strength, has excellent punching performance, is high in storage stability, and overcomes the defect that the existing coating liquid is not resistant to storage.

The self-adhesive insulating coating liquid for the electrical steel comprises the following components in percentage by weight:

the epoxy resin is a polymer oligomer which contains two or more epoxy groups, takes an organic compound such as aliphatic, alicyclic or aromatic as a framework and can form a thermal curing product through the reaction of the epoxy groups. The epoxy resin used in the invention is one or more of bisphenol A type glycidyl ether, bisphenol F type glycidyl ether, bisphenol S type glycidyl ether, polyphenol type glycidyl ether and aliphatic glycidyl ether, and the preferred epoxy resin is bisphenol A type glycidyl ether. The epoxy value of the epoxy resin used in the invention is 0.06-0.51, and the preferable epoxy value range is 0.12-0.44.

The maleic anhydride polymer is a curing agent of epoxy resin. The maleic anhydride polymer can not cure the epoxy resin at normal temperature, can coexist with the epoxy resin for a long time, ensures long-term stability of the dried coating, but can react with an epoxy group under high temperature and pressure to form a cross-linking compound to cure the epoxy resin. After the maleic anhydride polymer is used for curing the epoxy resin, the temperature resistance of the epoxy resin can be greatly improved, and the cured product can resist the high temperature of more than 300 ℃. The maleic anhydride polymer used in the present invention has the following structure:

in the formula, R is a monomer copolymerized with maleic anhydride, and can be one or more of acrylic acid, acrylate, styrene, methyl vinyl ether and vinyl acetate, and the preferable comonomer is styrene and acrylate; the m value ranges from 4 to 20, the preferable m value ranges from 4 to 10, the n value ranges from 0 to 20, and the preferable n value ranges from 2 to 8.

The cosolvent is an assistant which contains ether bonds in the structure and can increase the solubility of the epoxy resin. The cosolvent used in the invention has the following structure:

wherein p is 1 or 2, and q is in the range of 0-4. Preferred cosolvents are those corresponding to p ═ 1, q ═ 2 and p ═ 2, q ═ 1.

The emulsifier is an auxiliary agent capable of emulsifying and dispersing the epoxy resin in water to form an oil-in-water emulsion. The emulsifier is a surface active compound with both hydrophobic group and hydrophilic group, and the stability of the emulsion can be greatly improved by selecting a proper emulsifier. The emulsifier includes three types of cationic, anionic and nonionic. The emulsifier used in the invention is one or more of anionic emulsifier and polyether nonionic emulsifier, the anionic emulsifier comprises sodium (potassium) alkylbenzene sulfonate, sodium (potassium) fatty acid and the like, and the polyether nonionic emulsifier has the following structure:

in the formula, R' is a polyether initiator group and comprises one or more of hydrogen base, fatty alcohol base, alkylphenol base, castor oil base, fatty acid base, fatty amine base, sorbitol ester base and fatty acid ester base, the preferred initiator group is propylene glycol base, the range of s value is 4-30, the preferred s value is 6-20, the range of t value is 0-20, and the preferred t value is 4-10.

A preparation method of the self-adhesive insulating coating liquid for the electrical steel comprises the following steps:

step 1, mixing epoxy resin, maleic anhydride polymer, cosolvent and emulsifier, heating to 60-90 ℃, and violently stirring for 30-60 minutes;

step 2, slowly adding deionized water into the mixture obtained in the step 1 under stirring until the viscosity of the mixture is reduced to form an emulsion, continuously stirring for 20-60 minutes, and cooling to room temperature;

and 3, adding deionized water into the emulsion obtained in the step 2 to dilute the emulsion until the solid content is 30-50%, sending the emulsion into an emulsification homogenizer to homogenize the emulsion for 30-90 minutes, and discharging the emulsion to obtain the adhesive insulating coating liquid.

The insulating coating liquid is coated on the surface of the electrical steel, the electrical steel with the self-adhesive insulating coating is obtained after the electrical steel is cooled and coiled after being baked, the coating is in a dormant state and has no adhesiveness, the electrical steel with the coating is subjected to cold cutting, punching and stacking, and the self-adhesive insulating coating is activated after pressurization and temperature rise so as to bond and stack the electrical steel sheets.

The invention has the advantages of

The coating formed by baking the coating liquid coated on the surface of the electrical steel has good peel strength and toughness, can resist the mechanical processing of electrical steel such as curling, cold cutting, punching and the like, can realize the bonding and stacking of the steel sheets by heating and pressurizing after stacking the electrical steel sheets, avoids the damage of the connecting modes such as welding, bolting or riveting and the like to the insulating coating, has simple and convenient construction, and is convenient for continuous production.

The coating liquid is uniform emulsion liquid and does not contain insoluble solid particles, and the coating prepared by the coating liquid has good uniformity and good stability and can be stored for a long time.

Detailed Description

Example 1

Adding 340 g of E44 epoxy resin, 50 g of maleic anhydride-styrene copolymer (the molar ratio of maleic anhydride to styrene is 1: 1, the number average molecular weight is 10000), 200 g of ethylene glycol monopropyl ether and 120 g of AEO-9 emulsifier into a 1L mechanical stirring reaction kettle, heating to 65 ℃, stirring vigorously for 30 minutes, adding deionized water into the system at a speed of 20 ml per minute, observing the viscosity of the system while adding, stopping adding water when the viscosity of the system is suddenly reduced, forming milky emulsion in the reaction kettle, stirring continuously for 45 minutes, cooling to room temperature, continuously adding deionized water into the system until the total mass of the emulsion is 1000 g, stirring continuously for 30 minutes, transferring the emulsion into an emulsifying homogenizer, homogenizing for 1 hour, and discharging to obtain the self-adhesive insulating coating liquid for the electric steel.

Example 2

The raw materials comprise: 420 g of E20 epoxy resin, 36 g of maleic anhydride-vinyl acetate copolymer (monomer molar ratio 1: 1, number average molecular weight 8200), 120 g of ethylene glycol monomethyl ether, 160 g of OP-10 emulsifier, an emulsification temperature of 72 ℃, and the rest of the preparation process is the same as that of example 1.

Example 3

The raw materials comprise: 500 g of bisphenol F type epoxy resin having an epoxy value of 0.28, 66 g of maleic anhydride-methyl acrylate copolymer (monomer molar ratio 1: 1, number average molecular weight 7000), 80 g of ethylene glycol monomethyl ether, 220 g of Tween-20 emulsifier, an emulsification temperature of 75 ℃ and the same preparation process as in example 1 were carried out.

Example 4

The raw materials comprise: 100 g of E51 epoxy resin, 300 g of resorcinol bisglycidyl ether type epoxy resin with an epoxy value of 0.81, 45 g of maleic anhydride-methyl vinyl ether copolymer (monomer molar ratio 1: 1, number average molecular weight 7500), 48 g of ethylene glycol monomethyl ether, 130 g of OP-6 emulsifier, 40 g of sodium dodecyl benzene sulfonate, an emulsification temperature of 70 ℃, and the rest of the preparation process is the same as that of example 1.

Example 5

Coating the coating liquid on an electrical steel sheet (50mm multiplied by 0.5mm) by adopting a coating roller coating method, baking the coating liquid at 200 ℃ for 30 seconds, and cooling the coating liquid to room temperature to obtain a dormant self-adhesive coating, wherein the thickness of the coating is about 5-8 microns. The coated electrical steel sheet and the other uncoated electrical steel sheet were placed on a lamination frame and heated in a continuous furnace for 50 seconds, and immediately after the peak metal temperature of the electrical steel sheet reached 160 ℃, the two electrical steel sheets were laminated under a pressure of 2MPa, and after maintaining the lamination for 30 minutes, cooled in air to room temperature, and a self-adhesive insulating coating was formed between the electrical steel sheets.

Example 6

The adhesion properties (ISO 1519-2011 bending test) and corrosion resistance (GB6458-86 neutral salt spray test) of the coatings were evaluated, and the test results of the self-adhesive insulating coatings prepared from the coating liquids of examples 1 to 4 according to the method of example 5 are shown in Table 1.

TABLE 1

Examples	Storage stability (6 months)	Adhesion property	Corrosion resistance
				1	No precipitate	3mm pass through	Good effect
2	No precipitate	3mm pass through	Good effect
				3	No precipitate	3mm pass through	Good effect
4	No precipitate	3mm pass through	Good effect