Epoxy powder composition for micromotor as well as preparation method and application of epoxy powder composition

Abstract

The invention relates to the technical field of electronic component packaging materials, and discloses an epoxy powder composition for a micromotor, a preparation method and application, the composition comprises solid bisphenol A epoxy resin, polyfunctionality epoxy resin with functionality greater than 2, crystalline epoxy resin, an anhydride curing agent, a curing accelerator, a filler and an adhesion promoter, and other auxiliary agents such as a flexibilizer, a pigment and the like. Through the synergistic effect of specific components, the defects in the prior art are overcome, and the composition is high in curing speed and high in heat resistance; the cured coating is high in hardness, good in toughness and strong in adhesive force to a metal base material, and can effectively resist winding impact and cold and hot impact without cracking; the powder has excellent recycling performance in electrostatic fluidized bed coating, stability of coating parameters of an automatic production line can be guaranteed, and the powder utilization rate is remarkably increased; and meanwhile, the product meets the environmental protection requirements of no halogen, RoHS2.0 and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic component packaging materials, and in particular to an epoxy powder composition for micromotors, a preparation method and applications thereof. Background Art

[0002] Electrical insulation powder coatings are widely used for insulation protection of electronic components such as magnetic rings, busbars, and micromotors. With the rise of new energy electric vehicles, intelligent mechanical automation, robotics, and low-altitude economy industries, the demand for various micromotors is increasing.

[0003] A micro motor refers to a motor with a diameter of less than 160mm or a rated power of less than 750W. Micro motors are often used in control systems or transmission mechanical loads to realize functions such as detection, analytical calculation, amplification, execution or conversion of electromechanical signals or energy.

[0004] At present, the main functional requirements of electrical insulation powder coatings for micro motors are: 1. Higher curing speed to meet the needs of online curing; 2. After curing, the higher coating hardness and adhesion to the silicon steel sheet ensure that the coating will not crack during winding and ensure insulation; 3. The coating extracted by the coating machine must be recyclable to improve the utilization efficiency of the insulating powder and save costs; 4. Has high heat resistance.

[0005] Currently, electrical insulation powders for micromotors can only meet part of the above requirements.

[0006] Therefore, the market is in urgent need of a powder composition and a preparation method thereof that can simultaneously meet the main functions of the above-mentioned electrical insulating powder coating for micromotors.

[0007] The applicant's prior patent application, CN115948097A, primarily addresses the issue of magnetic rings' resistance to double-85 humidity. However, the performance of the composition falls short of the requirements for electrical insulation powder coatings for motors. Powder recycling presents challenges, and the hardness after in-line curing is unsatisfactory. Building on this existing technical solution, the applicant conducted in-depth research and proposed an improved epoxy powder composition for micromotors and its preparation method. Summary of the Invention

[0008] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the present invention provides an epoxy powder composition for micro motors, a preparation method and an application thereof.

[0009] An epoxy powder composition for micro motors, Its components and weight parts are: Epoxy resin - 35-50 parts; Epoxy resin 2-10 parts; Epoxy resin 1-5 parts; 4-10 parts of anhydride curing agent; 0.05-2 parts of curing accelerator; 30-55 parts of filler; 1 to 5 parts of adhesion promoter; 0.5-2 parts of charge enhancer; 1 to 6 parts of toughening agent; Pigment 0.05-5 parts; 0.5-2 parts of leveling agent; Add 0.1-0.5 parts of thixotropic agent; Epoxy resin 1 is a solid bisphenol A type epoxy resin with a softening point of 60-130°C and an epoxy equivalent weight of 450-1800 g / eq; The second epoxy resin is a multifunctional epoxy resin having a functionality greater than 2; The epoxy resin is a crystalline epoxy resin. Furthermore, after curing, the epoxy powder composition for micromotors has a coating with a Barcol hardness of ≥50 and no cracking, a glass transition temperature of ≥110°C, an electrical strength of ≥30 kV / mm, thermal shock resistance of ≥500 times, a chlorine content of ≤900 ppm, a bromine content of ≤900 ppm, and a total chlorine and bromine content of ≤1500 ppm.

[0010] Furthermore, the epoxy resin 1 is one or more of E12, NPES907, GESR907, NPES904, GESR904, GESR903, CYD-014U, CYD-014, CYD-012, and CYD-011; The second epoxy resin is one or more of novolac epoxy resin, o-cresol novolac epoxy resin, bisphenol A novolac epoxy resin, dicyclopentadiene epoxy resin, trifunctional epoxy resin, and tetrafunctional epoxy resin; The epoxy resin three is a crystalline epoxy resin containing a biphenyl structure, a sulfide structure, a phenylene structure, and a naphthalene structure, and one or more of them are selected.

[0011] Furthermore, the anhydride curing agent is one or more of phthalic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, benzophenone tetracarboxylic dianhydride, and ethylene glycol trimellitic anhydride; The curing accelerator is one or a combination of two or more of quaternary ammonium salts, quaternary phosphonium salts, organic phosphines, imidazoles and their derivatives; wherein the imidazole substances are 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-undecyl imidazolium-trimellitate, 1-cyanoethyl-2-phenylimidazolium-trimellitate, 1-cyanoethyl-2-phenylimidazolium-trimellitate powder, 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine powder, 2,4'-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4'-diamino-6-[2 '-Undecyl imidazolyl-(1 ')]-ethyl-s-triazine, 2,4'-diamino-6-[2'-methylimidazolyl-(1 ')]-ethyl-s-triazine; one or more of 2-phenylimidazole isocyanuric acid adduct, 2,4'-diamino-6-[2'-methylimidazolyl-(1 ')]-ethyl-s-triazine isocyanuric acid adduct dehydrate, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole powder, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole powder.

[0012] Furthermore, the filler is one or more of silicon micropowder, talc, mica powder, calcium silicate, zirconium silicate, calcium carbonate, barium sulfate, kaolin, montmorillonite, alumina, aluminum hydroxide, and boehmite; The adhesion promoter is one or more of aluminum tripolyphosphate, modified aluminum tripolyphosphate, and aluminum dihydrogen tripolyphosphate.

[0013] Furthermore, the toughening agent is a core-shell particle, and one or more of silicone core-shell particles, polyacrylate core-shell particles, and MBS core-shell particles are selected; The pigment is one or more of rutile titanium dioxide, anatase titanium dioxide, phthalocyanine blue, iron red, iron yellow, organic yellow pigment, organic red pigment, organic orange pigment, carbon black, and inorganic black pigment; The added thixotropic agent is one or more of fumed silica and fumed alumina; The leveling agent is a polybutyl acrylate leveling agent.

[0014] Furthermore, the charge enhancer is one or more of a compound of hindered amine and alkanolamine, a quaternary ammonium salt, an imidazoline compound, a polar fatty acid ester or a metal salt thereof; The leveling agent is GLP588 or GLP701.

[0015] Application of the aforementioned epoxy powder composition for micro motors in micro motor insulation protection, The epoxy powder composition for micro motors is applied to micro motor silicon steel sheets through an electrostatic fluidized bed coating process to form a coating. After curing, the coating does not crack during the winding process and has a thermal shock resistance of ≥500 times; and the powder recycling time is ≥12 hours.

[0016] A method for preparing the aforementioned epoxy powder composition for micro motors, comprising the steps of: S1, weighing epoxy resin 1, epoxy resin 2, epoxy resin 3, anhydride curing agent, curing accelerator, filler, adhesion promoter, charge enhancer, toughening agent, pigment and leveling agent according to a proportion and placing them in a high-speed mixer, mixing at a speed of 500-1500 rpm for 5-15 minutes to obtain a premixed dry powder; S2, adding the premixed dry powder obtained in S1 into a twin-screw extruder, setting the temperature to 80-120°C, and melting the resin by screw shearing and uniformly mixing it with other components to obtain a molten mixture; S3, cooling the molten mixture obtained in S2 through a cooling roller and pressing it into a thin sheet to obtain a sheet; S4, feeding the sheet obtained in S3 into an ACM mill for pulverization, and collecting powder particles with a particle size of 45 microns, accounting for 30% to 45% through air separation and screening processes; S5, mixing the powder particles obtained in S4 with an external thixotropic agent to make the powder fluidizable and fluffy, thereby obtaining the epoxy powder composition for the micromotor.

[0017] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1. By adding a charge enhancer, this invention improves the charge consistency between coarse and fine particles, resolving the problem of powder recycling during electrostatic fluidized bed coating. It also reduces the Faraday cage effect and improves powder uniformity within the V-groove of the micromotor. This technical approach enhances the stability of coating parameters in fully automated coating lines, increases powder utilization, and saves costs.

[0018] 2. The present invention increases the curing speed of the system and the glass transition temperature of the cured product by adding a multifunctional epoxy resin and coordinating it with an acid anhydride curing agent, thereby improving the heat resistance of the coating.

[0019] 3. By adding a crystalline epoxy resin, the present invention reduces the viscosity of the melt system and improves the wettability of the melt on the micromotor silicon steel sheet, thereby enhancing the adhesion of the coating to the micromotor. A polyaluminum phosphate-based inorganic adhesion promoter is also added. Its function is to react with the metal substrate via phosphorus hydroxyl groups to form a phosphate ester iron salt compound, which becomes a component of the phosphate film. Furthermore, the phosphorus hydroxyl groups form a strong chelating effect with the metal substrate surface, thereby interacting with the polyvalent metal to form a complex, firmly connecting the polymer to the metal substrate via a covalent bond. This adhesion, generated by the formation of chemical bonds, is not reduced by moisture. The combination of the crystalline epoxy resin and the polyaluminum phosphate-based inorganic adhesion promoter solves the coating's adhesion issues in both dry and wet states.

[0020] 4. The present invention can absorb the impact stress from the winding by adding core-shell polymer particles. At the same time, epoxy resin 1, epoxy resin 2, epoxy resin 3 and acid anhydride curing agent are combined to give the coating higher strength, so that the cured coating can resist high and low temperature impact, prevent the coating from cracking, and improve the insulation reliability of the coating.

[0021] 5. The epoxy powder composition of the present invention can meet the halogen-free environmental protection requirements (Cl≤900ppm, Br≤900ppm, Cl+Br≤1500ppm), meets ROHS2.0, and is a green environmentally friendly product.

[0022] 6. This epoxy powder composition is mainly used for insulation protection of various micromotors and can meet the requirements of fully automatic electrostatic fluidized bed coating process. It can also be used for insulation protection of electronic components such as busbars and magnetic rings.

[0023] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0025] An epoxy powder composition for micro motors, comprising the following components in parts by weight: Epoxy resin - 35-50 parts; Epoxy resin 2-10 parts; Epoxy resin 1-5 parts; 4-10 parts of anhydride curing agent; 0.05-2 parts of curing accelerator; 30-55 parts of filler; 1 to 5 parts of adhesion promoter; 0.5-2 parts of charge enhancer; 1 to 6 parts of toughening agent; Pigment 0.05-5 parts; 0.5-2 parts of leveling agent; Add 0.1 to 0.5 parts of thixotropic agent.

[0026] The existing epoxy powder composition for micromotors has a slow curing speed during use and does not meet the requirements of online curing. In this embodiment, high-speed online curing is achieved by combining epoxy resin with an anhydride curing agent and a curing accelerator.

[0027] To prevent cracking during winding due to low hardness and poor adhesion of the cured coating, epoxy resins 1, 2, and 3 are combined with an anhydride curing agent to increase hardness. Epoxy resin 3 is combined with an adhesion promoter and a toughening agent to improve adhesion and resist cracking.

[0028] The insulating powder of the original formula cannot be recycled and needs to be replaced frequently, resulting in great waste. The inventors have greatly improved the recycling rate by adding a charge enhancer and an appropriate amount of the charge enhancer.

[0029] The original formula produced a low Tg (glass transition temperature) for the cured product, resulting in poor heat resistance. By combining epoxy resins 1, 2, and 3 with an anhydride curing agent, the Tg of the cured product can be effectively increased. Tg is the glass transition temperature.

[0030] The first epoxy resin is a solid bisphenol A epoxy resin with a softening point of 60-130°C and an epoxy equivalent weight of 450-1800 g / eq. Examples include E12, NPES907, GESR907, NPES904, GESR904, GESR903, CYD-014U, CYD-014, CYD-012, and CYD-011. The first epoxy resin used in the present invention may be one or a mixture of two or more.

[0031] The second epoxy resin is a multifunctional epoxy resin having a functionality greater than 2, such as a novolac epoxy resin, an o-cresol epoxy resin, a bisphenol A novolac epoxy resin, a dicyclopentadiene epoxy resin, a trifunctional epoxy resin, or a tetrafunctional epoxy resin. The second epoxy resin used in the practice of the present invention may be one or a mixture of two or more.

[0032] Epoxy resin three is a crystalline epoxy resin. Crystalline epoxy resins are highly crystalline, meaning that at temperatures below their melting point, the polymer chains are regularly arranged in a solid state. When temperatures exceed their melting point, they melt into a low-viscosity liquid. Examples include crystalline epoxy resins containing biphenyl structures, sulfide structures, phenylene structures, and naphthalene structures. The epoxy resin three used in the present invention may be one or a mixture of two or more.

[0033] Anhydride curing agents are commonly used curing agents for epoxy resins, such as phthalic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, benzophenone tetracarboxylic dianhydride, ethylene glycol trimellitic anhydride, etc. The anhydride curing agent used in the present invention is one or a mixture of two or more.

[0034] A curing accelerator selected from the group consisting of quaternary ammonium salts, quaternary phosphonium salts, organic phosphines, imidazoles and derivatives thereof, or a combination of two or more thereof; wherein the imidazole substances (2-methylimidazole (2MZ), or 2-phenylimidazole (2PZ), or 2-phenyl-4-methylimidazole (2P4MZ)), 1-cyanoethyl-2-undecylimidazolium-trimellitate (C11Z-CNS), 1-cyanoethyl-2-phenylimidazolium-trimellitate (2PZCNS), 1-cyanoethyl-2-phenylimidazolium-trimellitate powder (2PZCNS-PW), 2,4'-diamino-6-[2'-methylimidazol-(1')]-ethyl-s-triazine (2MZ-A), 2,4'-diamino-6-[2'-methylimidazol-(1')]-ethyl-s-triazine powder (2MZA-PW), 2,4 '-Diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine (2E4MZ-A), 2,4'-diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine (C11Z-A), 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine (2MZ-A); 2-phenylimidazole isocyanuric acid adduct (2PZ-OK), 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct dehydrate (2MA-OK), 2-phenyl-4,5-dihydroxymethylimidazole (2PHZ), 2-phenyl-4 ,5-dihydroxymethylimidazole micropowder (2PHZ-PW), 2-phenyl-4-methyl-5-hydroxymethylimidazole (2P4MHZ), 2-phenyl-4-methyl-5-hydroxymethylimidazole micropowder (2P4MHZ-PW).

[0035] The filler is one or a combination of two or more of silicon micropowder, talc, mica powder, calcium silicate, zirconium silicate, calcium carbonate, barium sulfate, kaolin, montmorillonite, aluminum oxide, aluminum hydroxide, and boehmite; The adhesion promoter is one of aluminum tripolyphosphate, modified aluminum tripolyphosphate, and aluminum dihydrogen tripolyphosphate, or a combination of two or more thereof; The charge enhancer is one or a combination of two or more of a hindered amine and alkanolamine compound, a quaternary ammonium salt, an imidazoline compound, a polar fatty acid ester, or a metal salt thereof; The toughening agent is a core-shell particle, generally a soft core and a hard shell with good stress absorption, such as one or a combination of two or more of silicone core-shell particles, polyacrylate core-shell particles, and MBS core-shell particles; The pigment is one or a combination of two or more of rutile titanium dioxide, anatase titanium dioxide, phthalocyanine blue, iron red, iron yellow, organic yellow pigment, organic red pigment, organic orange pigment, carbon black, and inorganic black pigment; The leveling agent is a polybutyl acrylate leveling agent, such as GLP588, GLP701, etc.; The added thixotropic agent is one of fumed silica and fumed alumina, or a combination of the two; The preparation method of the oxygen powder composition for micro motors comprises the following steps: The various raw materials except the added thixotropic agent are pre-mixed in a high-speed mixer at a rotation speed of 500-1500 rpm for 5-15 minutes, and then added to a twin-screw extruder at a temperature set at 80-120°C. The resin is melted under the shearing state of the screw and then uniformly mixed with the other raw materials. The melt is cooled by a cooling roller and then enters an ACM mill for crushing. After air separation and screening, particles of the desired particle size are collected. Finally, the added thixotropic agent is added to make the powder fluidized and fluffy, thereby preparing an epoxy powder composition for micromotors.

[0036] The names of the specific raw material models selected in the embodiments and comparative examples are as follows: Epoxy resin one is CYD-012, epoxy resin two is HP7200, epoxy resin three is YX-4000, the anhydride curing agent is trimellitic anhydride or a combination of trimellitic anhydride and phthalic anhydride, the curing accelerator is triphenylphosphine or 2E4MZ-A, the filler is silica powder or wollastonite or calcium carbonate, the charge enhancer is TEHA triisooctylamine, the toughening agent is Mitsubishi Midabron S-2030, the pigments are titanium dioxide and phthalocyanine blue, the leveling agent is GLP588, and the external thixotropic agent is fumed silica or fumed alumina or a combination of the two.

[0037] The following describes in detail the formulations of the examples. These examples represent successful or optimized variations of the present invention and are intended to demonstrate various approaches to achieving target properties (such as moisture and heat resistance, mechanical strength, and process suitability) through the synergistic effects of different components.

[0038] Example 1 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: triphenylphosphine, 0.15 parts; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0039] Manufacturing method: Various raw materials except fumed alumina are pre-mixed in a high-speed mixer with a rotation speed of 500-1500rpm for 5-15 minutes, and then added to a twin-screw extruder with the temperature set at 80-120°C. The resin is melted under the shearing state of the screw and then mixed evenly with other raw materials. The melt is cooled by a cooling roller and then enters an ACM grinder for crushing. After air separation and screening, particles of the required particle size are collected. Finally, an external thixotropic agent is added to make the powder fluidized and fluffy, thereby obtaining a moisture-heat-resistant epoxy powder composition for magnetic rings.

[0040] Example 2 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0041] The manufacturing method is the same as that of Example 1.

[0042] Example 3 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: wollastonite, 40 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0043] The manufacturing method is the same as that of Example 1.

[0044] Example 4 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: calcium carbonate, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0045] The manufacturing method is the same as that of Example 1.

[0046] Example 5 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 6 parts; Anhydride curing agent: tetrahydrophthalic anhydride, 1.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0047] The manufacturing method is the same as that of Example 1.

[0048] Example 6 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 6 parts; Anhydride curing agent: tetrahydrophthalic anhydride, 1.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed silica, 0.2 parts.

[0049] The manufacturing method is the same as that of Example 1.

[0050] Example 7 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 6 parts; Anhydride curing agent: tetrahydrophthalic anhydride, 1.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.1 part; Additional thixotropic agent: fumed silica, 0.1 part.

[0051] The manufacturing method is the same as that of Example 1.

[0052] Comparative Example 1 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Phenolic hydroxy resin curing agent: 15 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0053] The manufacturing method is the same as that of Example 1.

[0054] Comparative Example 2 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0055] The manufacturing method is the same as that of Example 1.

[0056] Comparative Example 3 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0057] The manufacturing method is the same as that of Example 1.

[0058] Comparative Example 4 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Charge enhancer: TEHA triisooctylamine, 1 part; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0059] The manufacturing method is the same as that of Example 1.

[0060] Comparative Example 5 Epoxy resin 1: CYD012, 40 parts; Epoxy resin 2: HP7200, 8 parts; Epoxy resin 3: YX4000, 2 parts; Anhydride curing agent: trimellitic anhydride, 7.5 parts; Curing accelerator: 2E4MZ-A, 1 part; Filler: silicon micropowder, 50 parts; Adhesion promoter: aluminum tripolyphosphate, 3 parts; Toughening agent: Mitsubishi Meida Brun S-2030, 4 parts; Pigment: titanium dioxide, 2 parts; Pigment: Phthalocyanine blue, 0.3 parts; Leveling agent: GLP588, 1 part; Additional thixotropic agent: fumed alumina, 0.2 parts.

[0061] The manufacturing method is the same as that of Example 1.

[0062] In order to verify the beneficial effects of the invention, relevant project inspections are carried out.

[0063] The test results of the specific embodiments and comparative examples are listed in Table 1 and Table 2, respectively.

[0064] The inspection items and methods related to the present invention are as follows: Powder properties: horizontal flow rate, gel time, 45 micron laser particle size; Powder cycling resistance: electrostatic fluidized bed coating; Barcol hardness: Verify the quick reactivity of the coating: Cured material properties: electrical strength, cured material Tg, resistance to cold and hot shock; Environmentally friendly substances: chlorine (Cl), bromine (Br), RoHS2.0 test items.

[0065] The performance index test method is as follows: (1) Horizontal flow rate: According to 5.1.6 of GB / T28859-2012 "Epoxy Powder Encapsulant for Electronic Components", the temperature is set at 150±2℃ and the holding time is 30 minutes.

[0066] (2) Gelation time: According to the method in GB / 16995-1997 "Determination of gelation time of thermosetting powder coatings at a given temperature", the temperature is set at 160±2℃.

[0067] (3) 45 μm laser particle size, based on GBT19077-2016 “Particle size distribution by laser diffraction method”.

[0068] (4) Cycling resistance of electrostatic fluidized bed coating powder.

[0069] (5) Barcol hardness: Silicon steel sheet spray coating, coating thickness 0.2 ~ 0.4mm, 230℃ / 90 seconds after curing, use Barcol hardness tester to test Barcol hardness.

[0070] (6) Electrical strength: According to GB / T1408.1-2016 "Electrical strength test methods for insulating materials - Part 1: Tests at power frequency", test specimens with a diameter of approximately 100 mm and a thickness of approximately 0.5 mm were pressed into a mold, with 5 pieces per group. After curing, the electrical strength of the specimens was tested in insulating oil.

[0071] (7) Tg of cured product: According to GB / T 36800.2 "Thermomechanical analysis (TMA) of plastics - Part 2: Determination of linear thermal expansion coefficient and glass transition temperature", the coating is sampled after being cured at 230℃ / 90 seconds and tested by TMA method.

[0072] (8) Resistance to thermal shock: According to TCSTM 00971 "Thermosetting powder coatings for electrical insulation", the tinplate spray coating thickness is 0.18~0.22mm, after curing at 200℃ / 1H, the test is carried out at -40±2℃ to + (85±2)℃ for 10 minutes each, and the conversion time is less than 5 minutes, which is resistant to thermal shock.

[0073] (9) Environmentally friendly substances: ① Chlorine (Cl), bromine (Br), in accordance with IEC 61249-2-21.

[0074] ②RoHS2.0 test items, based on RoHS2.0.

[0075] Beneficial effects of the present invention: 1. Comparing Example 2 with Comparative Example 1, the use of a phenolic hydroxyl curing agent in Comparative Example 1 resulted in a slower reaction rate, resulting in cracking of the coating on the silicon steel sheet after curing at 230°C for 90 seconds, making hardness measurement impossible. Therefore, an anhydride curing agent with a faster cure speed and higher crosslink density was selected.

[0076] 2. Comparing Example 2 with Comparative Example 2, the omission of epoxy resin II in Comparative Example 2 resulted in a slower cure rate and lower crosslink density after curing at 230°C for 90 seconds. This resulted in cracking and detachment of the coating during hardness testing. Therefore, the addition of a multifunctional epoxy resin was necessary to increase the crosslink density and improve the coating's Barcol hardness.

[0077] 3. Comparing Example 2 with Comparative Example 3, the omission of epoxy resin III in Comparative Example 3 resulted in poor adhesion to the silicon steel sheet after curing at 230°C for 90 seconds. The crosslink density of the cured product decreased, and the coating cracked and fell off during hardness testing. Therefore, the addition of a bonding epoxy was necessary to reduce the melt viscosity, improve wettability of the melt with the micromotor silicon steel sheet, and enhance adhesion.

[0078] 4. Comparing Example 2 with Comparative Example 4, the core-shell toughening agent was omitted from Comparative Example 4. This resulted in insufficient toughness and cracking of the coating on the silicon steel sheet after curing at 230°C for 90 seconds. Furthermore, the coating cracked during thermal shock resistance testing. Therefore, the addition of a core-shell toughening agent was necessary to counteract stress damage.

[0079] 5. Comparing Example 2 with Comparative Example 5, the removal of the charge enhancer in Comparative Example 5 resulted in poor powder recyclability in the electrostatic fluidized bed coating system, failing to meet recycling requirements. Therefore, the addition of a charge enhancer was necessary to improve the charge consistency between coarse and fine particles and address powder recyclability issues during electrostatic fluidized bed coating. During use, the coating became thinner after each cycle, requiring frequent adjustment of coating parameters.

[0080] The present invention utilizes the above-mentioned technical means to prepare an epoxy powder composition for micromotors. This composition meets the requirements of a fully automated electrostatic fluidized bed coating process for micromotors, exhibits rapid curing, is recyclable, and exhibits stable coating parameters. It also meets halogen-free and RoHS 2.0 environmental protection requirements. The cured product can withstand external stress without cracking, and exhibits a high Tg that meets heat resistance requirements. This epoxy powder composition has high market application value and prospects, and deserves further promotion and use.

[0081] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

[0082] Table 1 Performance test results of the embodiment

[0083] Table 2 Performance test results of comparative examples

[0084] Comparative analysis of the above test results demonstrates that the epoxy powder composition for micromotors produced using the methods and formulations of the present invention exhibits excellent performance, meeting market demands for various properties. Furthermore, the epoxy powder composition for micromotors of the present invention exhibits a multi-component, coordinated, and complementary enhancement of its functions. Optimization of its components and formulations ensures that its functions and effects meet market demands.

[0085] The specific comparative analysis of Example 2 and the comparative examples demonstrates the function and indispensability of each key component in the following system. The "subtraction method" study not only verifies the rationality of the formulation design, but also deeply reveals that the failure of each component may lead to the collapse of the overall performance.

[0086] Example 2 and Comparative Example 1 - Curing System: Comparison of Kinetics of Acid Anhydride and Phenolic Resin.

[0087] Comparative Example 1, in which the anhydride curing agent in Example 2 was replaced with a phenolic hydroxyl resin curing agent, resulted in catastrophic mechanical failure. Data showed that the coating in Comparative Example 1 cracked directly during the Barcol hardness test, rendering a valid hardness value unobtainable. The root cause of this phenomenon lies in a mismatch in the curing reaction kinetics.

[0088] The gelation time of the anhydride system of Example 2 at 160°C is 50 seconds, while that of the phenolic system of Comparative Example 1 is as long as 70 seconds. Within the rapid curing process window of 230°C and 90 seconds, the difference of 20 seconds is decisive. The reaction speed of the phenolic resin curing system is relatively slow, and it is impossible to achieve sufficient cross-linking within 90 seconds. Incomplete curing leads to a loose polymer network structure and weak forces between molecular chains, which cannot form sufficient cohesive strength to resist external stress. Therefore, when the pressure needle of the hardness tester applies pressure, the stress inside the material cannot be effectively transmitted and dissipated, but is quickly concentrated and leads to the generation and expansion of macro cracks, which eventually manifests as brittle cracks in the coating.

[0089] It's worth noting that while the electrical strength of Comparative Example 1 is as high as 52.56 kV / mm, far exceeding the 42.8 kV / mm of Example 2, this indicator is meaningless given the complete failure of mechanical properties. An insulating coating that can't maintain its structural integrity, no matter how high its electrical performance, will be useless in practical applications. This comparison strongly demonstrates that the precise matching of the formulation's reaction kinetics with production process parameters (such as curing temperature and time) is the primary prerequisite for ensuring the performance of the final product.

[0090] Example 2 and Comparative Example 2 - Crosslink Density: Effect of Multifunctional Epoxy Resin.

[0091] Comparative Example 2 removes the multifunctional epoxy resin (HP7200) from the baseline formulation. This modification directly weakens the thermomechanical stability and structural integrity of the cured product. The most direct evidence of this is the sharp drop in the glass transition temperature (Tg), from 136.2°C in Example 2 to 108°C in Comparative Example 2.

[0092] Tg is a key indicator of the thermal stability of amorphous polymers and is closely related to the polymer's crosslink density. Multifunctional epoxy resins (such as epoxy novolac resins), due to the presence of multiple epoxy groups in their molecular structure, can form highly branched and crosslinked networks during the curing reaction. These dense chemical bonds firmly bind the polymer chains together, limiting their mobility when heated, thereby increasing the material's Tg.

[0093] After removing HP7200, the average functionality of the system decreased, resulting in a significant decrease in the density of the cross-linked network formed. This not only significantly reduced the thermal stability of the material (Tg dropped by about 28°C), but also seriously weakened its mechanical strength. A network with low cross-linking density has insufficient cohesion and rigidity to resist mechanical stress. Therefore, in the Barcol hardness test, the coating cracked at a lower hardness value (52) and was accompanied by shedding. This shows that HP7200 is not a simple additive, but a core skeleton for building the thermomechanical properties and structural integrity of the formulation.

[0094] Example 2 and Comparative Example 3 - Interface and Rheology: Functionality of Crystalline Epoxy Resins.

[0095] Comparative Example 3, in which the crystalline epoxy resin (YX4000) was removed, also resulted in cracking (hardness 55) and detachment of the coating during the hardness test. This failure mode reveals that the ultimate performance of the coating depends not only on the mechanical properties of the coating itself but also on the interfacial bonding strength between it and the substrate.

[0096] Crystalline epoxy resins serve a dual purpose in the formulation. At curing temperatures (e.g., 230°C), their crystalline structure melts, significantly reducing the viscosity of the entire melt system. According to the Wenzel and Cassie-Baxter models, this lower melt viscosity facilitates sufficient spreading and penetration of the melt onto the substrate surface, effectively wetting the microscopic pits and pores on the substrate surface, thereby maximizing the physical contact area. This excellent wettability is the foundation for a strong mechanical anchoring effect.

[0097] When YX4000 is removed, the melt viscosity of the system is relatively high and the fluidity becomes poor. Within the limited curing time, the melt cannot fully wet the substrate, resulting in a physically weak interface between the coating and the metal substrate. Although the cured coating body may have a certain hardness, under the action of local high stress in the hardness test, the weak interface becomes a stress concentration point, and cracks can easily initiate here and extend along the interface, eventually causing the coating to crack and peel off from the substrate. This case clearly shows that for coating applications, optimizing interface performance is as important as optimizing bulk performance.

[0098] Example 2 and Comparative Example 4 - Toughness: Effect of Core-Shell Tougheners.

[0099] Comparative Example 4 retained a high Tg (137.4°C) and high hardness (65) while removing the core-shell toughening agent (S-2030). As a result, the coating cracked during the hardness test and completely failed (NG) in the more stringent thermal shock resistance test. This result perfectly illustrates the key role of toughness in high-crosslink density epoxy systems.

[0100] Epoxy resins with high crosslink density are inherently hard and brittle. While their rigid network structure provides high hardness and a high Tg, it also renders them virtually indestructible when subjected to impact or stress, effectively absorbing energy and leading to rapid crack propagation. Core-shell toughening agents incorporate a large number of nanoscale "soft" phases dispersed within a rigid epoxy matrix. These toughening agents typically consist of a rubbery core (such as polybutadiene or acrylate) and a shell that exhibits excellent compatibility with the epoxy matrix.

[0101] When the material is subjected to stress, these nanoscale soft cores act as stress concentration points, inducing local yielding and shear band formation in the substrate, or absorbing and dissipating energy through cavitation, effectively preventing microcracks from developing into catastrophic macrofracture. In hardness testing, despite high hardness values, Comparative Example 4, which lacks a toughening agent, cracked, demonstrating its lack of damage tolerance. Thermal shock testing amplifies this weakness: under intense temperature cycling from -40°C to 85°C, the mismatch in the coefficient of thermal expansion (CTE) between the coating and the metal substrate generates significant internal stresses. For brittle materials, such internal stresses are sufficient to initiate cracking. The failure of Comparative Example 4 in this test directly demonstrates the irreplaceable role of core-shell toughening agents in imparting resistance to thermal stress and mechanical shock, ensuring long-term service reliability.

[0102] Example 2 and Comparative Example 5 - Process Stability: Effect of Charge Enhancer.

[0103] Comparative Example 5, which removed the charge enhancer (TEHA), exhibited excellent post-curing performance (Tg, hardness, and thermal shock resistance) comparable to Example 2. However, it failed the process-related test for "electrostatic fluidized bed coating powder cycling resistance," demonstrating thinning of the coating after cycling and the need for frequent adjustment of coating parameters. This phenomenon reveals a significant issue concerning the feasibility of industrial production, beyond laboratory performance.

[0104] In the electrostatic fluidized bed coating process, powder that does not adhere to the workpiece is recovered and recycled. Powder particles acquire an electrostatic charge during fluidization and friction. Ideally, powder particles of all sizes should have a uniform charge-to-mass ratio to ensure a stable, uniform powder cloud formed under the action of the electric field. However, in practice, due to the particle size distribution, fine and coarse powders have different specific surface areas, resulting in different charging and aerodynamic behaviors.

[0105] Without a charge enhancer, charge stratification or separation between fine and coarse powders can occur over long periods of circulation. For example, fine powder may become overcharged and be excessively repelled, or undercharged and settle, resulting in a change in the particle size distribution of the recycled powder. This instability ultimately manifests in uneven or gradually thinning coating thickness, forcing operators to frequently adjust equipment parameters, severely impacting production efficiency and consistent product quality.

[0106] The role of a charge enhancer (such as TEHA tri-isooctylamine) is to regulate and stabilize the charge properties of the entire powder system, ensuring that particles of varying sizes receive a stable and consistent charge, thereby maintaining the uniformity of the powder cloud. The failure of Comparative Example 5 eloquently demonstrates that a commercially successful formulation must not only meet performance requirements but also possess excellent process robustness and be adaptable to large-scale, long-term continuous production.

[0107] The results clearly show that the success of epoxy powder compositions for micromotors does not stem from a single "magic component," but is based on a highly synergistic, multifaceted, and balanced complex system whose success depends on the synergistic effects of its components.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An epoxy powder composition for micro motors, characterized in that: Its components and weight parts are: Epoxy resin - 35-50 parts; Epoxy resin 2-10 parts; Epoxy resin 1-5 parts; 4-10 parts of anhydride curing agent; 0.05-2 parts of curing accelerator; 30-55 parts of filler; 1 to 5 parts of adhesion promoter; 0.5-2 parts of charge enhancer; 1 to 6 parts of toughening agent; Pigment 0.05-5 parts; 0.5-2 parts of leveling agent; Add 0.1-0.5 parts of thixotropic agent; Epoxy resin 1 is a solid bisphenol A type epoxy resin with a softening point of 60-130°C and an epoxy equivalent weight of 450-1800 g / eq; The second epoxy resin is a multifunctional epoxy resin having a functionality greater than 2; Epoxy resin three is a crystalline epoxy resin.

2. The epoxy powder composition for micro motor according to claim 1, characterized in that: After curing, the epoxy powder composition for micro motor has a coating with a Barcol hardness of ≥50 and no cracking, a glass transition temperature of ≥110°C, an electrical strength of ≥30 kV / mm, resistance to thermal shock of ≥500 times, a chlorine content of ≤900 ppm, a bromine content of ≤900 ppm, and a total content of chlorine and bromine of ≤1500 ppm.

3. The epoxy powder composition for micro motor according to claim 1, characterized in that: Epoxy resin 1 is one or more of E12, NPES907, GESR907, NPES904, GESR904, GESR903, CYD-014U, CYD-014, CYD-012, and CYD-011; The second epoxy resin is one or more of novolac epoxy resin, o-cresol novolac epoxy resin, bisphenol A novolac epoxy resin, dicyclopentadiene epoxy resin, trifunctional epoxy resin, and tetrafunctional epoxy resin; The epoxy resin three is a crystalline epoxy resin containing a biphenyl structure, a sulfide structure, a phenylene structure, and a naphthalene structure, and one or more of them are selected.

4. The epoxy powder composition for micro motor according to claim 1, characterized in that: The anhydride curing agent is one or more of phthalic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, benzophenone tetracarboxylic dianhydride, and ethylene glycol trimellitic anhydride; The curing accelerator is one or a combination of two or more of a quaternary ammonium salt, a quaternary phosphonium salt, an organic phosphine, an imidazole and its derivatives; wherein the imidazole substance is 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-undecyl imidazolium-trimellitate, 1-cyanoethyl-2-phenylimidazolium-trimellitate, 1-cyanoethyl-2-phenylimidazolium-trimellitate powder, 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine powder, 2,4'-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4'-diamino-6-[2 '-Undecyl imidazolyl-(1 ')]-ethyl-s-triazine, 2,4'-diamino-6-[2'-methylimidazolyl-(1 ')]-ethyl-s-triazine; one or more of 2-phenylimidazole isocyanuric acid adduct, 2,4'-diamino-6-[2'-methylimidazolyl-(1 ')]-ethyl-s-triazine isocyanuric acid adduct dehydrate, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole powder, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole powder.

5. The epoxy powder composition for micro motor according to claim 1, characterized in that: The filler is one or more of silicon micropowder, talc, mica powder, calcium silicate, zirconium silicate, calcium carbonate, barium sulfate, kaolin, montmorillonite, alumina, aluminum hydroxide, and boehmite; The adhesion promoter is one or more of aluminum tripolyphosphate, modified aluminum tripolyphosphate, and aluminum dihydrogen tripolyphosphate.

6. The epoxy powder composition for micro motor according to claim 1, characterized in that: The toughening agent is a core-shell particle, and one or more of silicone core-shell particles, polyacrylate core-shell particles, and MBS core-shell particles are selected; The pigment is one or more of rutile titanium dioxide, anatase titanium dioxide, phthalocyanine blue, iron red, iron yellow, organic yellow pigment, organic red pigment, organic orange pigment, carbon black, and inorganic black pigment; The added thixotropic agent is one or more of fumed silica and fumed alumina; The leveling agent is a polybutyl acrylate leveling agent.

7. The epoxy powder composition for micro motor according to claim 6, characterized in that: The charge enhancer is one or more of a hindered amine and alkanolamine compound, a quaternary ammonium salt, an imidazoline compound, a polar fatty acid ester or a metal salt thereof; The leveling agent is GLP588 or GLP701.

8. Use of the epoxy powder composition for micro motors according to any one of claims 1 to 7 in micro motor insulation protection, characterized in that: The epoxy powder composition for micro motor is applied to the silicon steel sheet of the micro motor through an electrostatic fluidized bed coating process to form a coating. After curing, the coating does not crack during the winding process and has a thermal shock resistance of ≥500 times; Powder recycling time ≥ 12 hours.

9. A method for preparing the epoxy powder composition for micro motors according to any one of claims 1 to 7, characterized in that: The steps include, S1, weighing epoxy resin 1, epoxy resin 2, epoxy resin 3, anhydride curing agent, curing accelerator, filler, adhesion promoter, charge enhancer, toughening agent, pigment and leveling agent according to a proportion and placing them in a high-speed mixer, mixing at a speed of 500-1500 rpm for 5-15 minutes to obtain a premixed dry powder; S2, adding the premixed dry powder obtained in S1 into a twin-screw extruder, setting the temperature to 80-120°C, and melting the resin by screw shearing and uniformly mixing it with other components to obtain a molten mixture; S3, cooling the molten mixture obtained in S2 through a cooling roller and pressing it into a thin sheet to obtain a sheet; S4, feeding the sheet obtained in S3 into an ACM mill for pulverization, and collecting powder particles with a particle size of 45 microns, accounting for 30% to 45% through air separation and screening processes; S5, mixing the powder particles obtained in S4 with an external thixotropic agent to make the powder fluidizable and fluffy, thereby obtaining the epoxy powder composition for the micromotor.

Images