A self-adhesive coating for amorphous silicon steel sheets and its preparation method

Abstract

This invention discloses a self-adhesive coating for amorphous silicon steel sheets and its preparation method, belonging to the field of coating preparation technology. First, an epoxy resin is generated by polymerizing epichlorohydrin with 4-aminoquinoline, improving thermal stability and effectively reducing mechanical losses after coating. Then, it is reacted with phloroglucinol to obtain a modified epoxy resin, which exhibits tight inward molecular aggregation, increasing crosslinking density. Next, the ring-opening reaction of ethylene glycol diglycidyl ether with 3,5-dichloroaniline enhances crosslinking properties, followed by a reaction with lacquer resin to improve coating stability. The resulting self-adhesive coating can bond tightly to the iron core, reducing NVH levels, decreasing eddy current losses and iron losses, improving the energy conversion efficiency of the motor, and enhancing hydrophobicity.

Description

Technical Field

[0001] This invention relates to the field of coating preparation technology, specifically to a self-adhesive coating for amorphous silicon steel sheets and its preparation method. Background Technology

[0002] Self-adhesive iron cores are a crucial component of drive motors in new energy vehicles. Their primary function is to tightly bond the stator core laminations together using a special functional coating, achieving a unified connection. This structure not only improves the motor's electromagnetic performance but also optimizes its heat dissipation, thereby enhancing overall motor performance. In new energy electric drive systems, the application of self-adhesive iron cores makes motors more compact and efficient, reduces vibration and noise, and improves the overall driving experience. In recent years, with the rapid development of the new energy vehicle industry, countries such as Europe, the United States, and Japan have begun to apply this technology to drive motors. During the core manufacturing process, amorphous silicon steel sheets, due to their unique internal structure, offer advantages over silicon steel sheets, including lower losses, lower coercivity, and higher resistivity. They are increasingly used in transformer and motor core applications. However, amorphous silicon steel sheets are hard, brittle, and not heat-resistant, making welding or riveting impossible. Applying a self-adhesive coating to the surface of amorphous silicon steel sheets, under specific process conditions, allows for the firm bonding of the amorphous wafers together to form the core. This solves the problems of welding or riveting amorphous wafers and also addresses issues arising from impregnation and cutting.

[0003] However, existing solvent-based self-adhesive coatings suffer from solvent evaporation, which poses a significant health risk. All-organic coatings or self-adhesive coatings doped with inorganic nanoparticles have relatively low thermal conductivity. When used to fabricate motor lamination cores, the poor thermal conductivity of the coating hinders heat dissipation from the core, limiting the application of self-adhesive coatings. Furthermore, most existing self-adhesive coatings use dicyandiamide as a curing agent, with a small number using systems incorporating imidazole, amino resins, or isocyanates. Since curing epoxy resin with dicyandiamide requires high temperatures (above 150°C), it is difficult to control during production. Therefore, inventing a solvent-free self-adhesive coating with high thermal conductivity, good adhesion, and improved mechanical properties is crucial to address these issues. Summary of the Invention

[0004] The purpose of this invention is to provide a self-adhesive coating for amorphous silicon steel sheets and its preparation method, so as to solve the problems existing in the prior art.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a self-adhesive coating for amorphous silicon steel sheets, wherein the self-adhesive coating for amorphous silicon steel sheets comprises component A and component B.

[0006] Furthermore, component A includes modified epoxy resin, nano titanium dioxide, BYK-A530, and propylene oxide benzyl ether.

[0007] Furthermore, the modified epoxy resin is prepared from epichlorohydrin, 4-aminoquinoline, and phloroglucinol.

[0008] Furthermore, component B includes a modified curing agent.

[0009] Furthermore, the modified curing agent is prepared from ethylene glycol diglycidyl ether, 3,5-dichloroaniline, and lacquer resin.

[0010] Furthermore, a method for preparing a self-adhesive coating for amorphous silicon steel sheets includes the following preparation steps:

[0011] (1) Mix 23-45 parts of epichlorohydrin and 16-38 parts of 4-aminoquinoline evenly, heat to 80℃ and react for 6-8 hours, then add 7-29 parts of 10%wt potassium hydroxide aqueous solution and continue to react for 5-7 hours. Separate the liquid to remove the bottom salt water, add 134-356 parts of toluene and 107-221 parts of water to extract three times, take the organic phase and add 15-53 parts of 10%wt phosphoric acid to the pH value of 7-8, wash three times with 80-176 parts of water, concentrate and dry to obtain composite epoxy resin;

[0012] (2) 22-50 parts of composite epoxy resin and 6-14 parts of phloroglucinol are heated to 100-140°C under nitrogen protection and completely dissolved. Then, 0.01-0.03 parts of catalyst T are added and reacted for 1-3 hours. After reacting for 2-4 hours, the temperature is raised to 150°C and the reaction is carried out for 2-4 hours. The temperature is then cooled to 20-30°C to obtain modified epoxy resin.

[0013] (3) Heat 14 to 33 parts of 3,5-dichloroaniline to 70 to 90°C, melt it, and then add 10 to 24 parts of ethylene glycol diglycidyl ether within a certain time. React for 1 to 3 hours to obtain a composite curing agent.

[0014] (4) Add 17-33 parts of lacquer tree acid and 8-24 parts of triethylamine to 85-165 parts of ethanol, heat to 60-70℃ and then add 12-28 parts of composite curing agent, react for 7-11 hours, concentrate and dry to obtain modified curing agent.

[0015] (5) Mix 50-80 parts of modified epoxy resin, 13-21 parts of nano titanium dioxide, 5-9 parts of BYK-A530 and 2-4 parts of epoxy propylene phenyl ether, stir for 15-45 minutes, and then grind until the slurry particle size is qualified to obtain component A.

[0016] (6) Mix 21-27 parts of component A with 19-31 parts of component B to obtain a self-adhesive coating.

[0017] Furthermore, the concentration in step (1) is as follows: vacuum degree -0.1MPa~-0.05MPa, concentration time 1~5h; drying is as follows: drying at 50~70℃ for 2~10h.

[0018] Furthermore, the certain time mentioned in step (3) is 1~2h.

[0019] Furthermore, the concentration in step (4) is: vacuum degree -0.08MPa~-0.04MPa, concentration time 1~7h; drying is: drying at 60~70℃ for 2~8h.

[0020] Furthermore, the qualified particle size in step (5) is: D50 in the range of 0.1μm to 0.5μm.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0022] This invention uses a mixture of modified epoxy resin and modified curing agent to form an oil-based, solvent-free self-adhesive coating, which adheres tightly to the stator core to optimize the NVH performance and improve efficiency of the self-adhesive core.

[0023] First, the modified epoxy resin is prepared from epichlorohydrin, 4-aminoquinoline, and phloroglucinol. Epoxy resin is generated by polymerizing epichlorohydrin and 4-aminoquinoline, utilizing the strong conjugation of benzene rings and nitrogen heterocycles to improve the resin's thermal stability. After coating, it effectively reduces mechanical losses and improves motor efficiency. Then, it reacts with phloroglucinol, resulting in tight inward molecular aggregation, enhancing flexibility and increasing crosslinking density. Based on this, it tightly bonds with the iron core, reducing the overall NVH level of the vehicle, improving driving comfort, and reducing noise pollution to the environment during vehicle operation.

[0024] Secondly, the modified curing agent utilizes the highly reactive epoxy groups in ethylene glycol diglycidyl ether to undergo a ring-opening reaction with 3,5-dichloroaniline containing amino groups, enhancing crosslinking, improving the fluidity and coatability of the coating, and reducing the viscosity of the resin. Then, it reacts with the carboxyl groups in lacquer resin to introduce polar hydroxyl groups, which combine with iron elements on the iron core surface, reducing eddy current loss and iron loss, and improving the energy conversion efficiency of the motor. At the same time, the carbon-15 straight chain containing unsaturated double bonds has excellent hydrophobicity, low permeability, and self-drying properties, improving flexibility. On this basis, the benzene ring has good free radical scavenging and heat resistance, which can neutralize harmful free radicals and improve the stability of the coating. Detailed Implementation

[0025] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0026] To more clearly illustrate the method provided by the present invention, the following embodiments are provided in detail. The test methods for various indicators of the self-adhesive coating for amorphous silicon steel sheets prepared in the following embodiments are as follows:

[0027] Adhesion strength: The self-adhesive coatings of the examples and comparative examples were uniformly applied to the sample pieces, and after curing, the test was carried out in accordance with GB / T2791-1995 "Test method for peel strength of adhesives, flexible materials to flexible materials".

[0028] Adhesion: The self-adhesive coatings of the examples and comparative examples were uniformly coated on the sample sheets. After curing, the adhesion was tested in accordance with GB / T2522-2017 "Test Method for Insulation Resistance and Adhesion of Coatings of Electrical Steel Strips (Sheets)".

[0029] Noise generated at 1.5T: The self-adhesive coatings of the examples and comparative examples were uniformly applied to the stator core, cured, and the engine was started to measure the noise.

[0030] Example 1

[0031] (1) Mix 23 parts epichlorohydrin and 16 parts 4-aminoquinoline evenly, heat to 80℃ and react for 6 hours, add 7 parts 10%wt potassium hydroxide aqueous solution and continue to react for 5 hours, separate the bottom salt and alkaline water, add 134 parts toluene and 107 parts water to extract three times, take the organic phase and add 15 parts 10%wt phosphoric acid to the pH value 7, wash 80 parts water three times, concentrate under vacuum of -0.1MPa for 1 hour and dry at 50℃ for 2 hours to obtain composite epoxy resin;

[0032] (2) 22 parts of composite epoxy resin and 6 parts of phloroglucinol were heated to 100°C under nitrogen protection and completely dissolved. Then, 0.01 parts of catalyst T were added and reacted for 1 hour. After reacting for 2 hours, the temperature was raised to 150°C and reacted for 2 hours. The temperature was then cooled to 20°C to obtain modified epoxy resin.

[0033] (3) Heat 14 parts of 3,5-dichloroaniline to 70°C, melt it, and add 10 parts of ethylene glycol diglycidyl ether within 1 hour. React for 1 hour to obtain a composite curing agent.

[0034] (4) Add 17 parts of lacquer tree acid and 8 parts of triethylamine to 85 parts of ethanol, heat to 60°C and add 12 parts of composite curing agent, react for 7 hours, concentrate under vacuum of -0.08MPa for 1 hour and dry at 60°C for 2 hours to obtain modified curing agent.

[0035] (5) Mix 50 parts of modified epoxy resin, 13 parts of nano titanium dioxide, 5 parts of BYK-A530 and 2 parts of epoxy propylene phenyl ether, stir for 15 min, and then perform sand milling until the particle size D50 of the slurry is 0.1 μm to obtain component A.

[0036] (6) Mix 21 parts of component A with 19 parts of component B to obtain a self-adhesive coating.

[0037] Example 2

[0038] (1) Mix 34 parts of epichlorohydrin and 27 parts of 4-aminoquinoline evenly, heat to 80℃ and react for 7h, then add 18 parts of 10%wt potassium hydroxide aqueous solution and continue to react for 6h. Separate the liquid to remove the bottom salt water, add 245 parts of toluene and 164 parts of water to extract three times, take the organic phase and add 34 parts of 10%wt phosphoric acid to the pH value 7.5, wash three times with 128 parts of water, concentrate under vacuum of -0.075MPa for 3h and dry at 60℃ for 6h to obtain composite epoxy resin;

[0039] (2) 36 parts of composite epoxy resin and 10 parts of phloroglucinol were heated to 120°C under nitrogen protection and completely dissolved. Then, 0.02 parts of catalyst T were added and reacted for 2 hours. After reacting for 3 hours, the temperature was raised to 150°C and reacted for 3 hours. The temperature was then cooled to 25°C to obtain modified epoxy resin.

[0040] (3) Heat 23.5 parts of 3,5-dichloroaniline to 80°C, melt it, and add 17 parts of ethylene glycol diglycidyl ether within 1.5 h. React for 2 h to obtain a composite curing agent.

[0041] (4) Add 25 parts of lacquer tree acid and 16 parts of triethylamine to 125 parts of ethanol, heat to 65℃ and then add 20 parts of composite curing agent. React for 9 hours, concentrate under vacuum of -0.06MPa for 4 hours and dry at 65℃ for 5 hours to obtain modified curing agent.

[0042] (5) Mix 65 parts of modified epoxy resin, 17 parts of nano titanium dioxide, 7 parts of BYK-A530 and 3 parts of epoxy propylene phenyl ether, stir for 30 min, and then perform sand milling until the particle size D50 of the slurry is 0.3 μm to obtain component A.

[0043] (6) Mix 24 parts of component A with 25 parts of component B to obtain a self-adhesive coating.

[0044] Example 3

[0045] (1) Mix 45 parts of epichlorohydrin and 38 parts of 4-aminoquinoline evenly, heat to 80℃ and react for 8 hours, then add 29 parts of 10%wt potassium hydroxide aqueous solution and continue to react for 7 hours. Separate the liquid to remove the bottom salt water, add 356 parts of toluene and 221 parts of water to extract three times, take the organic phase and add 53 parts of 10%wt phosphoric acid to the pH value 8, wash with 176 parts of water three times, concentrate under vacuum of -0.05MPa for 5 hours and dry at 70℃ for 10 hours to obtain composite epoxy resin;

[0046] (2) 50 parts of composite epoxy resin and 14 parts of phloroglucinol were heated to 140°C under nitrogen protection and completely dissolved. Then, 0.03 parts of catalyst T were added and reacted for 3 hours. After reacting for 4 hours, the temperature was raised to 150°C and cooled to 30°C to obtain modified epoxy resin.

[0047] (3) Heat 33 parts of 3,5-dichloroaniline to 90°C, melt it, and add 24 parts of ethylene glycol diglycidyl ether within 2 hours. React for 3 hours to obtain a composite curing agent.

[0048] (4) Add 33 parts of lacquer tree acid and 24 parts of triethylamine to 165 parts of ethanol, heat to 70°C and then add 28 parts of composite curing agent. React for 11 hours, concentrate under vacuum of -0.04MPa for 7 hours and dry at 70°C for 8 hours to obtain modified curing agent.

[0049] (5) Mix 80 parts of modified epoxy resin, 21 parts of nano titanium dioxide, 9 parts of BYK-A530 and 4 parts of epoxy propylene phenyl ether, stir for 45 min, and then grind in a sand mill until the particle size D50 of the slurry is 0.5 μm to obtain component A.

[0050] (6) Mix 27 parts of component A with 31 parts of component B to obtain a self-adhesive coating.

[0051] Comparative Example 1

[0052] The difference between Comparative Example 1 and Example 2 lies only in step (1). Step (1) is changed to: (1) Mix 34 parts of epichlorohydrin and 27 parts of bisphenol A evenly, heat to 80°C and react for 7 hours, then add 18 parts of 10%wt potassium hydroxide aqueous solution and continue reacting for 6 hours. Separate the liquid to remove the bottom salt water, add 245 parts of toluene and 164 parts of water to extract three times, take the organic phase and add 34 parts of 10%wt phosphoric acid to the pH value 7.5, wash three times with 128 parts of water, concentrate under vacuum of -0.075MPa for 3 hours and dry at 60°C for 6 hours to obtain composite epoxy resin. The remaining steps are the same as in Example 2.

[0053] Comparative Example 2

[0054] The difference between Comparative Example 2 and Example 2 is that step (2) is omitted. The remaining steps are the same as in Example 2.

[0055] Comparative Example 3

[0056] The difference between Comparative Example 3 and Example 2 is that step (3) is omitted, and step (4) is changed to: adding 25 parts of lacquer tree acid and 16 parts of triethylamine to 125 parts of ethanol, heating to 65°C, adding 20 parts of 3,5-dichloroaniline, reacting for 9 hours, concentrating under vacuum of -0.06 MPa for 4 hours, and drying at 65°C for 5 hours to obtain the modified curing agent. The remaining steps are the same as in Example 2.

[0057] Comparative Example 4

[0058] The difference between Comparative Example 4 and Example 2 is that step (3) is omitted, and step (4) is changed to: adding 25 parts of lacquer tree acid and 16 parts of triethylamine to 125 parts of ethanol, heating to 65°C, adding 20 parts of ethylene glycol glycidyl ether, reacting for 9 hours, concentrating under vacuum of -0.06 MPa for 4 hours, and drying at 65°C for 5 hours to obtain the modified curing agent. The remaining steps are the same as in Example 2.

[0059] Comparative Example 5

[0060] The difference between Comparative Example 5 and Example 2 is that step (4) is omitted. The remaining steps are the same as in Example 2.

[0061] Comparative Example 6

[0062] The difference between Comparative Example 6 and Example 2 lies in step (1). Step (1) is changed as follows: 34 parts of phenol and 27 parts of 4-aminoquinoline are mixed evenly, heated to 80°C and reacted for 7 hours. Then, 18 parts of 10%wt potassium hydroxide aqueous solution are added and the reaction continues for 6 hours. The bottom salt and alkaline water is removed by separation, and 245 parts of toluene and 164 parts of water are added for extraction three times. The organic phase is then treated with 34 parts of 10%wt phosphoric acid until the pH value reaches 7.5. The mixture is washed three times with 128 parts of water, concentrated under vacuum of -0.075MPa for 3 hours, and dried at 60°C for 6 hours to obtain the composite resin. The remaining steps are the same as in Example 2.

[0063] Example of effect

[0064] Table 1 below presents the performance analysis results of the self-adhesive coatings for amorphous silicon steel sheets using Examples 1 to 3 and Comparative Examples 1 to 6 of the present invention.

[0065]

[0066] A comparison of the experimental data from Examples 1, 2, and 3 with Comparative Example 1 reveals that the strong conjugation of benzene rings and nitrogen heterocycles improves the thermal stability of the resin, effectively reducing mechanical losses and improving motor efficiency after coating. A comparison of the experimental data from Examples 1, 2, and 3 with Comparative Example 2 reveals that the reaction with phloroglucinol enables the molecules to tightly aggregate, enhancing flexibility and increasing crosslinking density. Based on this, it tightly bonds with the iron core, reducing the overall NVH level of the vehicle, improving driving comfort, and reducing noise pollution during vehicle operation. A comparison of the experimental data from Examples 1, 2, and 3 with Comparative Example 3 reveals that the addition of ethylene glycol glycidyl ether improves the fluidity and coatability of the coating and reduces the viscosity of the resin. A comparison of the experimental data from Examples 1, 2, and 3 with Comparative Example 3 reveals that the addition of ethylene glycol glycidyl ether improves the fluidity and coatability of the coating and reduces the viscosity of the resin. A comparison of the experimental data from Comparative Example 4 reveals that the benzene ring in 3,5-dichloroaniline exhibits excellent free radical scavenging and heat resistance, which can neutralize harmful free radicals and improve coating stability. A comparison of the experimental data from Examples 1, 2, and 3 with Comparative Example 5 shows that the hydroxyl groups in lacquer resin can combine with iron elements on the iron core surface, reducing eddy current losses and iron losses, and improving the energy conversion efficiency of the motor. Simultaneously, the carbon-15 straight chain containing unsaturated double bonds possesses excellent hydrophobicity, low permeability, and self-drying properties, improving flexibility. A comparison of the experimental data from Examples 1, 2, and 3 with Comparative Example 6 reveals that epoxy resin has high bonding strength and cohesive strength, while also possessing good mechanical and electrical insulation properties, reducing copper losses and mechanical losses in the motor, and further improving motor efficiency.

[0067] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No markings in the claims should be construed as limiting the scope of the claims.

Claims

1. A self-adhesive coating for amorphous silicon steel sheets, characterized in that, The self-adhesive coating for amorphous silicon steel sheets comprises component A and component B; component A comprises modified epoxy resin, nano titanium dioxide, BYK-A530, and propylene oxide phenyl ether; the modified epoxy resin is prepared from epichlorohydrin, 4-aminoquinoline, and phloroglucinol; component B comprises a modified curing agent; the modified curing agent is prepared from ethylene glycol diglycidyl ether, 3,5-dichloroaniline, and lacquer resin.

2. A method for preparing a self-adhesive coating for amorphous silicon steel sheets according to claim 1, characterized in that, The preparation steps include the following: (1) Mix 23-45 parts of epichlorohydrin and 16-38 parts of 4-aminoquinoline evenly, heat to 80℃ and react for 6-8 hours, then add 7-29 parts of 10%wt potassium hydroxide aqueous solution and continue to react for 5-7 hours. Separate the liquid to remove the bottom salt water, add 134-356 parts of toluene and 107-221 parts of water to extract three times, take the organic phase and add 15-53 parts of 10%wt phosphoric acid to the pH value of 7-8, wash three times with 80-176 parts of water, concentrate and dry to obtain composite epoxy resin; (2) 22-50 parts of composite epoxy resin and 6-14 parts of phloroglucinol are heated to 100-140°C under nitrogen protection and completely dissolved. Then, 0.01-0.03 parts of catalyst T are added and reacted for 1-3 hours. After reacting for 2-4 hours, the temperature is raised to 150°C and the reaction is carried out for 2-4 hours. The temperature is then cooled to 20-30°C to obtain modified epoxy resin. (3) Heat 14 to 33 parts of 3,5-dichloroaniline to 70 to 90°C, melt it, and then add 10 to 24 parts of ethylene glycol diglycidyl ether within a certain time. React for 1 to 3 hours to obtain a composite curing agent. (4) Add 17-33 parts of lacquer tree acid and 8-24 parts of triethylamine to 85-165 parts of ethanol, heat to 60-70℃ and then add 12-28 parts of composite curing agent, react for 7-11 hours, concentrate and dry to obtain modified curing agent; (5) Mix 50-80 parts of modified epoxy resin, 13-21 parts of nano titanium dioxide, 5-9 parts of BYK-A530, and 2-4 parts of epoxy propylene phenyl ether, stir for 15-45 minutes, and then grind the slurry until the particle size is qualified to obtain component A. (6) Mix 21-27 parts of component A with 19-31 parts of component B to obtain a self-adhesive coating.

3. The method for preparing a self-adhesive coating for amorphous silicon steel sheets according to claim 2, characterized in that, The concentration in step (1) is as follows: vacuum degree -0.1MPa~-0.05MPa, concentration time 1~5h; drying is as follows: drying at 50~70℃ for 2~10h.

4. The method for preparing a self-adhesive coating for amorphous silicon steel sheets according to claim 2, characterized in that, The time period mentioned in step (3) is 1~2 hours.

5. The method for preparing a self-adhesive coating for amorphous silicon steel sheets according to claim 2, characterized in that, The concentration in step (4) is as follows: vacuum degree -0.08MPa~-0.04MPa, concentration time 1~7h; drying is as follows: drying at 60~70℃ for 2~8h.

6. The method for preparing a self-adhesive coating for amorphous silicon steel sheets according to claim 2, characterized in that, The qualified particle size in step (5) is: D50 in the range of 0.1μm to 0.5μm.

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