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Self-bonding coating composition

A composition, self-adhesive technology, applied in the direction of coating, metal material coating process, nanotechnology for materials and surface science, etc., can solve the problem of coating without adhesion function, etc., to enhance mechanical stress resistance , excellent adhesive strength, excellent corrosion resistance effect

Inactive Publication Date: 2007-10-03
EI DU PONT DE NEMOURS & CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But such coatings have no bonding function and require additional bonding methods (welding, clamping, meshing, aluminum casting or riveting) to form a solid core

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] Preparation of coatings based on aqueous compositions according to the invention

[0058] An aqueous dispersion consisting of bisphenol A type epoxy resin with a solids content of 51% to 55% and 7% of 1-methoxy-2-propanol and less than 3% of benzyl alcohol and water was used as the adhesive. The amount of micronized dicyandiamide (calculated based on 100 parts of 100% solid epoxy resin) is shown in Table 1. Then add 2 parts by weight of flow reagent BYK  -341 and 12 parts by weight of diethylene glycol monobutyl ether. Stir the mixture until it becomes homogeneous. In the last step, add the nanoparticle Aerosil in the amount shown in Table 1  R 7200.

[0059] The coating composition was applied to electrical steel sheets by rollers and forced dried by PMT (Maximum Metal Temperature) 240 to 250°C to give an active coating with a film thickness of about 4 microns. Then, the steel sheet is divided into a certain size, at 3N / mm 2 Under the pressure and PMT condition...

Embodiment 2

[0065] Preparation of coatings based on solventborne compositions according to the invention

[0066] A solid solvent solution of high molecular weight epoxy resin based on bisphenol A was used as an adhesive. 40 to 50% solids were obtained using 1-methoxypropyl acetate-2. Novolac type phenolic resins and modified novolak resins (epoxy equivalent weight 160 to 170 g / equivalent, epoxy functionality 2.0) are used as cross-linking agents in amounts (each based on 100 parts 100% Solid epoxy resin calculation) as shown in Table 2. Then add 1 part by weight of flow reagent BYK  -310. In the final step, the nanoparticles Aerosil were added in the amount shown in Table 2.  R 7200 is added to the formula. Stir the mixture until it becomes homogeneous.

[0067] The coating composition was applied to electrical steel sheets by rollers and forced dried by a PMT (maximum metal temperature) of 220 to 230°C to give an active coating with a film thickness of about 4 microns. Then, th...

Embodiment 3

[0070] Comparison with state-of-the-art electrical steel sheet coatings

[0071] The NO.7 composition according to JPH11-193475 comprises: 100 parts by weight (solid) of water-dispersible bisphenol A type epoxy resin and 15 parts by weight (solid) of phenolic formaldehyde based on the reaction product of 1 mole of bisphenol A and 7 moles of formaldehyde The resin, the content of the methanoly component (the content is higher than that of the dimethanol component) is 98.3% by weight, mixed with water and stirred to obtain a coating composition with a solid content of 20% by weight.

[0072] Composition No. 4 of U.S. 10 / 788985 contains the same components as composition No. 4 (comprising 5 parts by weight of dicyandiamide) in Example 1 according to the present invention, but without any nanoparticles in the composition.

[0073] The application and drying procedure and the preparation of the steel sheet cores were as described in Examples 1 and 2.

[0074] combination ...

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Abstract

A self-bonding coating composition for the production of electrical steel sheets cores comprising; A) 100 parts per weight of at least one epoxy resin based on bisphenol-A-type and / or bisphenol-F-type, 100% of solids, B) 0.1 to 200 parts per weight of nano particles having an average radius ranging from 2 to 600 nm, C) 0 to 25 parts per weight of at least one curing agent selected from the group consisting of dicyandiamide, blocked isocyanate and Lewis acid or selected from the group consisting of phenolic resin, carboxylic acid, anhydride and Lewis acid, 100% of solids, D) 0.1 to 10 parts per weight of at least one additive, and E) 50 to 200 parts per weight of water or at least one organic solvent, ensuring increased re-softening temperatures as well as excellent bonding strength, corrosion resistance and electrical insulation of the coating.

Description

Background of the invention [0001] The present invention relates to self-adhesive coating compositions for the production of electrical steel sheet cores for use in electrical equipment. [0002] Self-bonding coating compositions, also called baking varnishes (enamel or coating compositions that require baking at elevated temperatures), are used to bond individual electrical steel sheets together to form a solid core for electrical equipment , such as transformers, generators and electric motors, and to provide electrical insulation between the metal sheets in the core. The coated metal sheets are bonded together by hot pressing. [0003] In general, the application of stoving lacquers is limited due to the relatively low resoftening temperature. The development of new products requires high resoftening temperatures for coatings, thereby expanding their range of applications in the field of electrical equipment. In addition, it is desirable to improve the following properti...

Claims

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Application Information

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IPC IPC(8): C08L63/02C23C22/02C09D7/62
CPCC08L63/00C08K3/22C08K3/36C08K9/08C09D7/1225C09D7/1266C09D7/1275C09D7/62C09D7/67C09D7/68C08K7/02C08K5/16B82Y30/00
Inventor M·韦默O·波戈迪纳F·-R·贝姆
Owner EI DU PONT DE NEMOURS & CO
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