An epoxy powder composition for micro-machines, a preparation method and applications thereof

Abstract

The present application relates to the technical field of electronic component packaging materials, and discloses an epoxy powder composition for micro-machines, a preparation method and application, which comprises the following components: solid bisphenol A type epoxy resin, multifunctional epoxy resin with functionality greater than 2, crystalline epoxy resin, acid anhydride curing agent, curing accelerator, filler, adhesion promoter, electric strength improver, and other additives such as toughening agent and pigment. The present application solves the problems of the prior art through the synergistic effect of specific components, and has the advantages that the composition has fast curing speed and high heat resistance; the cured coating has high hardness, good toughness, and strong adhesion to metal substrates, and can effectively resist winding impact and cold and hot impact without cracking; the composition has excellent recycling performance in electrostatic fluidized bed coating, can guarantee the stability of the coating parameters of the automatic production line, and significantly improves the utilization rate of the powder; and the product meets the environmental protection requirements of halogen-free and RoHS 2.0.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic component packaging materials, in particular to an epoxy powder composition for micro-motors, a preparation method and application. BACKGROUND

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

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

[0004] The main functional requirements of the electrical insulation powder coating for micro-motors at present are:

[0005] 1. High curing speed to meet the needs of online curing;

[0006] 2. High coating hardness and adhesion to silicon steel sheets after curing to ensure that the coating does not break during winding and to ensure insulation;

[0007] 3. The coating extracted by the coated machine should meet the characteristics of recycling to improve the utilization efficiency of the insulation powder and save costs;

[0008] 4. High heat resistance.

[0009] The electrical insulation powder for micro-motors at present can only meet part of the above requirements.

[0010] Therefore, there is an urgent need in the market for a powder composition that can simultaneously meet the main functions of the electrical insulation powder coating for micro-motors and a preparation method thereof.

[0011] The technical solution of the applicant's prior application patent CN115948097A mainly solves the problem of resistance to double 85 humidity of magnetic rings. The application performance of this composition has certain gaps with the demand of electrical insulation powder coating for motors, and there are certain difficulties in recycling the powder. The hardness after online curing is not ideal. The applicant has conducted in-depth research on the basis of the existing technical solution and proposes an improved epoxy powder composition for micro-motors and a preparation method thereof. SUMMARY

[0012] The present application aims to at least solve one of the technical problems in the related art. To this end, the present application provides an epoxy powder composition for micro-motors, a preparation method and application.

[0013] An epoxy powder composition for micro-motor,

[0014] The composition components and weight parts are as follows:

[0015] Epoxy resin I 35-50 parts;

[0016] Epoxy resin II 2-10 parts;

[0017] Epoxy resin III 1-5 parts;

[0018] Anhydride curing agent 4-10 parts;

[0019] Curing accelerator 0.05-2 parts;

[0020] Filler 30-55 parts;

[0021] Adhesion promoter 1-5 parts;

[0022] Electricity increasing agent 0.5-2 parts;

[0023] Toughening agent 1-6 parts;

[0024] Pigment 0.05-5 parts;

[0025] Leveling agent 0.5-2 parts;

[0026] External thixotropic agent 0.1-0.5 parts;

[0027] The epoxy resin I is a solid bisphenol A type epoxy resin, the softening point is 60-130℃, and the epoxy equivalent weight is 450-1800g / eq;

[0028] The epoxy resin II is a multifunctional epoxy resin with a functionality greater than 2;

[0029] The epoxy resin III is a crystalline epoxy resin. Further, the epoxy powder composition for micro-motor has a cured coating with a Barcol hardness ≥50 and no cracking, a glass transition temperature ≥110℃, an electrical strength ≥30kV / mm, a cold-heat shock resistance ≥500 times, a chlorine content ≤900ppm, a bromine content ≤900ppm, and a total content of chlorine and bromine ≤1500ppm.

[0030] Further, the epoxy resin I is one or more of E12, NPES907, GESR907, NPES904, GESR904, GESR903, CYD-014U, CYD-014, CYD-012, CYD-011;

[0031] The epoxy resin II is one or more of a phenolic epoxy resin, an o-cresol novolac epoxy resin, a bisphenol A type phenolic epoxy resin, a dicyclopentadiene type epoxy resin, a trifunctional epoxy resin, and a tetrafunctional epoxy resin.

[0032] The epoxy resin three is a crystalline epoxy resin containing a biphenyl structure, a thioether structure, a phenylene structure, and a naphthalene structure, and one or more of the epoxy resins is selected.

[0033] Further, the acid 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;

[0034] The curing accelerator is one or more of a quaternary ammonium salt, a quaternary phosphonium salt, an organic phosphine, an imidazole, and a derivative thereof; the imidazole is one or more of 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazolium-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'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4'-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine; 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.

[0035] Further, the filler is one or more of silicon powder, talc powder, mica powder, calcium silicate, zirconium silicate, calcium carbonate, barium sulfate, kaolin, montmorillonite, aluminum oxide, aluminum hydroxide, and brucite.

[0036] The adhesion promoter is one or more of aluminum tripolyphosphate, modified aluminum tripolyphosphate, and aluminum dihydrogen tripolyphosphate.

[0037] Further, the toughening agent is a core-shell particle, and one or more of an organic silicon core-shell particle, a polyacrylate core-shell particle, and an MBS core-shell particle is selected.

[0038] 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.

[0039] The additional thixotropic agent is one or more of fumed silica, fumed alumina;

[0040] The leveling agent is a polybutyl acrylate leveling agent.

[0041] Further, the electric strength 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;

[0042] The leveling agent is GLP588 or GLP701.

[0043] Application of the aforementioned epoxy powder composition for micro-machines in the insulation protection of micro-machines,

[0044] The epoxy powder composition for micro-machines is applied to a micro-machine silicon steel sheet through an electrostatic fluidized bed coating process to form a coating, and after curing, the coating has no cracking during the winding process, and the cold and hot impact resistance is ≥ 500 times; the powder recycling time is ≥ 12 hours.

[0045] A method for preparing the aforementioned epoxy powder composition for micro-machines, comprising the steps of,

[0046] S1, epoxy resin I, epoxy resin II, epoxy resin III, anhydride curing agent, curing accelerator, filler, adhesion promoter, electric strength enhancer, toughening agent, pigment and leveling agent are weighed according to the proportion and placed in a high-speed mixer, mixed at a speed of 500-1500 rpm for 5-15 minutes to obtain a premixed dry powder;

[0047] S2, the premixed dry powder obtained in S1 is added to a twin-screw extruder, and the temperature is set to 80-120℃, the resin is melted and uniformly mixed with other components by screw shearing to obtain a molten mixture;

[0048] S3, the molten mixture obtained in S2 is cooled and pressed into a sheet by a cooling press roller to obtain a sheet;

[0049] S4, the sheet obtained in S3 is sent into an ACM powder mill for grinding, and the powder particles with a particle size of 45 microns accounting for 30-45% are collected through the processes of air separation and screening;

[0050] S5, the powder particles obtained in S4 are mixed with an additional thixotropic agent to make the powder have fluidity and fluffiness to obtain the epoxy powder composition for micro-machines.

[0051] The aforementioned one or more technical solutions in the embodiments of the present application have at least one of the following technical effects:

[0052] 1. The present application improves the consistency of the charging of coarse particles and fine particles by adding a charge enhancer, solves the problem of powder recycling during electrostatic fluidized bed coating, reduces the Faraday cage effect and improves the uniformity of powder application in the V-shaped slot of a micro motor. Through this technical means, the stability of the coating parameters of the full-automatic coating production line is improved, the utilization rate of the powder is improved, and the cost is saved.

[0053] 2. The present application improves the curing speed of the system and the glass transition temperature of the cured product by adding a multifunctional epoxy resin and an acid anhydride curing agent, thereby improving the heat resistance of the coating.

[0054] 3. The present application reduces the viscosity of the melting system by adding a crystalline epoxy resin, improves the wettability of the melting system to the silicon steel sheet of the micro motor, thereby improving the adhesion of the coating to the micro motor. At the same time, an inorganic adhesion promoter of polyaluminum phosphate is added, which functions in that the phosphorus hydroxyl reacts with the metal substrate to form a phosphoric acid ester iron salt compound, which becomes one of the components of the phosphating film; further, the phosphorus hydroxyl forms a strong chelation with the surface of the metal substrate, thereby forming a complex with the polyvalent metal, and covalently bonding the polymer to the metal substrate, and the adhesion formed by the chemical bond will not be reduced due to moisture. The crystalline epoxy resin and the inorganic adhesion promoter of polyaluminum phosphate cooperate to solve the adhesion problem of the coating in dry and wet states.

[0055] 4. The present application can absorb impact stress from the coil by adding core-shell polymer particles, and the epoxy resin I, epoxy resin II, epoxy resin III and acid anhydride curing agent cooperate to give the coating a high 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.

[0056] 5. The epoxy powder composition of the present application can meet the requirements of halogen-free environmental protection (Cl≤900ppm, Br≤900ppm, Cl+Br≤1500ppm), meet ROHS2.0, and belong to green environmental protection products.

[0057] 6. The epoxy powder composition is mainly used for the insulation protection of various micro motors, and can meet the full-automatic electrostatic fluidized bed coating process. It can also be applied to the insulation protection of busbars, magnetic rings and other electronic components.

[0058] Additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the present application. DETAILED DESCRIPTION

[0059] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application. The following embodiments are used to illustrate the present application, but cannot be used to limit the scope of the present application.

[0060] An epoxy powder composition for micro-motor, the composition components and weight parts are as follows:

[0061] Epoxy resin one 35-50 parts;

[0062] Epoxy resin two 2-10 parts;

[0063] Epoxy resin three 1-5 parts;

[0064] Anhydride curing agent 4-10 parts;

[0065] Curing accelerator 0.05-2 parts;

[0066] Filler 30-55 parts;

[0067] Adhesion promoter 1-5 parts;

[0068] Electricity increasing agent 0.5-2 parts;

[0069] Toughening agent 1-6 parts;

[0070] Pigment 0.05-5 parts;

[0071] Leveling agent 0.5-2 parts;

[0072] External thixotropic agent 0.1-0.5 parts.

[0073] The original epoxy powder composition for micro-motor has slow curing speed in use, which cannot meet the online curing requirement. In the present embodiment, the combination of epoxy resin two, anhydride curing agent and curing accelerator realizes high-speed online curing.

[0074] In order to avoid low hardness and poor adhesion of the coating after curing, which leads to cracking during winding. The hardness is improved by the cooperation of epoxy resin one, epoxy resin two, epoxy resin three and anhydride curing agent; the adhesion is improved by the cooperation of epoxy resin three, adhesion promoter and toughening agent to resist cracking.

[0075] The original formula of the insulation powder cannot be recycled, and the powder needs to be replaced frequently, which causes great waste. The inventor adds the electricity increasing agent and the appropriate amount of the electricity increasing agent to greatly improve the recycling rate.

[0076] The cured product of the original formula has a low Tg and poor heat resistance. The Tg of the cured product can be effectively improved by using epoxy resin 1, epoxy resin 2, epoxy resin 3 and an acid anhydride curing agent. Tg is the glass transition temperature.

[0077] 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. For example, E12, NPES907, GESR907, NPES904, GESR904, GESR903, CYD-014U, CYD-014, CYD-012, CYD-011, etc. The epoxy resin 1 used in the present application is one or a mixture of two or more.

[0078] Epoxy resin 2 is a multifunctional epoxy resin with a functionality greater than 2, such as phenolic epoxy resin, o-cresol novolac epoxy resin, bisphenol A type phenolic epoxy resin, dicyclopentadiene type epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin. The epoxy resin 2 used in the present application is one or a mixture of two or more.

[0079] Epoxy resin 3 is a crystalline epoxy resin. Crystalline epoxy resin means a strong crystalline epoxy resin, which refers to a high molecular chain arranged in a solid state at a temperature below the melting point, and when the temperature exceeds the melting point, it melts into a low viscosity liquid. For example, crystalline epoxy resins containing biphenyl structure, thioether structure, phenylene structure, naphthalene structure, etc. The epoxy resin 3 used in the present application is one or a mixture of two or more.

[0080] An acid anhydride curing agent is a commonly used curing agent for epoxy resins, such as phthalic anhydride, pyromellitic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, trimellitic anhydride, benzophenone tetracarboxylic dianhydride, ethylene glycol trimellitic anhydride, etc. The acid anhydride curing agent used in the present application is one or a mixture of two or more.

[0081] Curing accelerator: one or more than two combinations of quaternary ammonium salt, quaternary phosphonium salt, organic phosphine, imidazole and its derivatives; wherein imidazole (2-methyl imidazole (2MZ), or 2-phenyl imidazole (2PZ), or 2-phenyl-4-methyl imidazole (2P4MZ)), 1-cyanoethyl-2-undecyl imidazolium-citraconic acid ester (C11Z-CNS), 1-cyanoethyl-2-phenyl imidazolium-citraconic acid ester (2PZCNS), 1-cyanoethyl-2-phenyl imidazolium-citraconic acid ester powder (2PZCNS-PW), 2,4'-diamino-6-[2'-methyl imidazolyl-(1')]-ethyl-s-triazine (2MZ-A), 2,4'-diamino-6-[2'-methyl imidazolyl-(1')]-ethyl-s-triazine powder (2MZA-PW), 2,4'-diamino-6-[2'-ethyl-4'-methyl imidazolyl-(1')]-ethyl-s-triazine (2E4MZ-A), 2,4'-diamino-6-[2'-undecyl imidazolyl-(1')]-ethyl-s-triazine (C11Z-A), 2,4'-diamino-6-[2'-methyl imidazolyl-(1')]-ethyl-s-triazine (2MZ-A); 2-phenyl imidazole isocyanuric acid adduct (2PZ-OK), 2,4'-diamino-6-[2'-methyl imidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct dehydrate (2MA-OK), 2-phenyl-4,5-dihydroxymethyl imidazole (2PHZ), 2-phenyl-4,5-dihydroxymethyl imidazole powder (2PHZ-PW), 2-phenyl-4-methyl-5-hydroxymethyl imidazole (2P4MHZ), 2-phenyl-4-methyl-5-hydroxymethyl imidazole powder (2P4MHZ-PW).

[0082] Filler: one or more than two combinations of silicon powder, talc powder, mica powder, calcium silicate, zirconium silicate, calcium carbonate, barium sulfate, kaolin, montmorillonite, aluminum oxide, aluminum hydroxide, and bohemite;

[0083] Adhesion promoter: one or more than two combinations of aluminum tripolyphosphate, modified aluminum tripolyphosphate, and aluminum dihydrogen tripolyphosphate;

[0084] Electricity increasing agent: one or more than two combinations of hindered amine and alkanol amine compound, quaternary ammonium salt, imidazoline compound, polar fatty acid ester, or metal salt thereof;

[0085] Toughening agent: one or more than two combinations of core-shell particles, generally soft core and hard shell have good stress absorption, such as silicone core-shell particles, polyacrylate core-shell particles, and MBS core-shell particles;

[0086] 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.

[0087] The leveling agent is a polybutyl acrylate leveling agent, such as GLP588, GLP701, etc.

[0088] The external thixotropic agent is one or a combination of two of fumed silica and fumed alumina.

[0089] The preparation method of the above-mentioned oxygen powder composition for micro-machines is as follows:

[0090] The various raw materials except the external thixotropic agent are pre-mixed in a high-speed mixer with a rotation speed of 500-1500 rpm for 5-15 minutes, then added to a twin-screw extruder with a temperature setting of 80-120°C, and the resin is melted under the shearing state of the screw to mix uniformly with other raw materials. The melt is cooled by a cooling roller, then crushed by an ACM mill, and then subjected to a winnowing process and sieving to collect particles of the desired particle size. Finally, the external thixotropic agent is added to make the powder fluidized and fluffy, thereby obtaining the epoxy powder composition for micro-machines.

[0091] The specific raw material types used in the examples and comparative examples are as follows:

[0092] The epoxy resin one is CYD-012, the epoxy resin two is HP7200, the 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 triphenyl phosphine or 2E4MZ-A, the filler is silicon powder or wollastonite or calcium carbonate, the electric strength enhancer is TEHA triisooctylamine, the toughening agent is Mitsubishi Mitsui Buren S-2030, the pigment is 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.

[0093] The formulation compositions of the examples will be described in detail below. These examples represent successful or optimized variants of the present technical solution, and are intended to demonstrate various approaches to achieving target properties (such as moisture and heat resistance, mechanical strength, process suitability, etc.) through the synergistic effects of different components.

[0094] Example 1

[0095] Epoxy resin one: CYD012, 40 parts;

[0096] Epoxy resin two: HP7200, 8 parts;

[0097] Epoxy resin three: YX4000, 2 parts;

[0098] Anhydride curing agent: trimellitic anhydride, 7.5 parts;

[0099] Curing accelerator: triphenylphosphine, 0.15 parts;

[0100] Filler: silicon powder, 50 parts;

[0101] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0102] Electricity increasing agent: TEHA triisooctylamine, 1 part;

[0103] Toughening agent: Mitsubishi Mitsui Breen S-2030, 4 parts;

[0104] Pigment: titanium white, 2 parts;

[0105] Pigment: phthalocyanine blue, 0.3 parts;

[0106] Leveling agent: GLP588, 1 part;

[0107] External thixotropic agent: fumed alumina, 0.2 parts.

[0108] Manufacturing method: Pre-mixing various raw materials except for fumed alumina in a high-speed mixer at a rotation speed of 500-1500 rpm for 5-15 minutes, then adding to a twin-screw extruder, setting the temperature at 80-120°C, melting the resin under the shear state of the screw, and uniformly mixing with other raw materials, the melt is cooled by a cooling roller, then enters the ACM mill for crushing, goes through the air separation process and screening, collects the particles of the desired particle size, and finally adds an external thixotropic agent to make the powder fluidized and fluffy, thus obtaining a moisture-resistant and heat-resistant epoxy powder composition for magnetic rings.

[0109] Example 2

[0110] Epoxy resin one: CYD012, 40 parts;

[0111] Epoxy resin two: HP7200, 8 parts;

[0112] Epoxy resin three: YX4000, 2 parts;

[0113] Anhydride curing agent: trimellitic anhydride, 7.5 parts;

[0114] Curing accelerator: 2E4MZ-A, 1 part;

[0115] Filler: silicon powder, 50 parts;

[0116] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0117] Electricity increasing agent: TEHA triisooctylamine, 1 part;

[0118] Toughening agent: Mitsubishi Chemical Brun S-2030, 4 parts

[0119] Pigment: titanium white, 2 parts

[0120] Pigment: phthalocyanine blue, 0.3 parts

[0121] Leveling agent: GLP588, 1 part

[0122] External thixotropic agent: fumed alumina, 0.2 parts

[0123] Manufacturing method same as Example 1.

[0124] Example 3

[0125] Epoxy resin one: CYD012, 40 parts

[0126] Epoxy resin two: HP7200, 8 parts

[0127] Epoxy resin three: YX4000, 2 parts

[0128] Anhydride curing agent: trimellitic anhydride, 7.5 parts

[0129] Curing accelerator: 2E4MZ-A, 1 part

[0130] Filler: wollastonite, 40 parts

[0131] Adhesion promoter: aluminum tripolyphosphate, 3 parts

[0132] Electricity increasing agent: TEHA triisooctylamine, 1 part

[0133] Toughening agent: Mitsubishi Chemical Brun S-2030, 4 parts

[0134] Pigment: titanium white, 2 parts

[0135] Pigment: phthalocyanine blue, 0.3 parts

[0136] Leveling agent: GLP588, 1 part

[0137] External thixotropic agent: fumed alumina, 0.2 parts

[0138] Manufacturing method same as Example 1.

[0139] Example 4

[0140] Epoxy resin one: CYD012, 40 parts

[0141] Epoxy resin two: HP7200, 8 parts

[0142] Epoxy resin three: YX4000, 2 parts

[0143] Anhydride curing agent: trimellitic anhydride, 7.5 parts;

[0144] Curing accelerator: 2E4MZ-A, 1 part;

[0145] Filler: calcium carbonate, 50 parts;

[0146] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0147] Electrical conductivity enhancer: TEHA triisooctylamine, 1 part;

[0148] Toughening agent: Mitsubishi Rayon Buren S-2030, 4 parts;

[0149] Pigment: titanium white, 2 parts;

[0150] Pigment: phthalocyanine blue, 0.3 parts;

[0151] Leveling agent: GLP588, 1 part;

[0152] External thixotropic agent: fumed alumina, 0.2 parts.

[0153] Manufacturing method same as Example 1.

[0154] Example 5

[0155] Epoxy resin one: CYD012, 40 parts;

[0156] Epoxy resin two: HP7200, 8 parts;

[0157] Epoxy resin three: YX4000, 2 parts;

[0158] Anhydride curing agent: trimellitic anhydride, 6 parts;

[0159] Anhydride curing agent: tetrahydrophthalic anhydride, 1.5 parts;

[0160] Curing accelerator: 2E4MZ-A, 1 part;

[0161] Filler: silicon powder, 50 parts;

[0162] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0163] Electrical conductivity enhancer: TEHA triisooctylamine, 1 part;

[0164] Toughening agent: Mitsubishi Rayon Buren S-2030, 4 parts;

[0165] Pigment: titanium white, 2 parts;

[0166] Pigment: phthalocyanine blue, 0.3 parts;

[0167] Leveling agent: GLP588, 1 part;

[0168] External thixotropic agent: fumed alumina, 0.2 parts.

[0169] The manufacturing method is the same as Example 1.

[0170] Example 6

[0171] Epoxy resin one: CYD012, 40 parts;

[0172] Epoxy resin two: HP7200, 8 parts;

[0173] Epoxy resin three: YX4000, 2 parts;

[0174] Anhydride curing agent: trimellitic anhydride, 6 parts;

[0175] Anhydride curing agent: tetrahydrophthalic anhydride, 1.5 parts;

[0176] Curing accelerator: 2E4MZ-A, 1 part;

[0177] Filler: silicon micro powder, 50 parts;

[0178] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0179] Electrical enhancer: TEHA triisooctylamine, 1 part;

[0180] Toughening agent: Mitsubishi Mitsui Bren S-2030, 4 parts;

[0181] Pigment: titanium white, 2 parts;

[0182] Pigment: phthalocyanine blue, 0.3 parts;

[0183] Leveling agent: GLP588, 1 part;

[0184] External thixotropic agent: fumed silica, 0.2 parts.

[0185] The manufacturing method is the same as Example 1.

[0186] Example 7

[0187] Epoxy resin one: CYD012, 40 parts;

[0188] Epoxy resin two: HP7200, 8 parts;

[0189] Epoxy resin three: YX4000, 2 parts;

[0190] Anhydride curing agent: trimellitic anhydride, 6 parts;

[0191] Anhydride curing agent: tetrahydrophthalic anhydride, 1.5 parts;

[0192] Curing accelerator: 2E4MZ-A, 1 part;

[0193] Filler: Silica powder, 50 parts;

[0194] Adhesion promoter: Aluminum tripolyphosphate, 3 parts;

[0195] Electricity increasing agent: TEHA triisooctylamine, 1 part;

[0196] Toughening agent: Mitsubishi Mitsui Breen S-2030, 4 parts;

[0197] Pigment: Titanium white, 2 parts;

[0198] Pigment: Phthalocyanine blue, 0.3 parts;

[0199] Leveling agent: GLP588, 1 part;

[0200] External thixotropic agent: Fumed alumina, 0.1 part;

[0201] External thixotropic agent: Fumed silica, 0.1 part.

[0202] Manufacturing method same as Example 1.

[0203] Comparative Example 1

[0204] Epoxy resin one: CYD012, 40 parts;

[0205] Epoxy resin two: HP7200, 8 parts;

[0206] Epoxy resin three: YX4000, 2 parts;

[0207] Phenolic hydroxyl resin curing agent: 15 parts;

[0208] Curing accelerator: 2E4MZ-A, 1 part;

[0209] Filler: Silica powder, 50 parts;

[0210] Adhesion promoter: Aluminum tripolyphosphate, 3 parts;

[0211] Electricity increasing agent: TEHA triisooctylamine, 1 part;

[0212] Toughening agent: Mitsubishi Mitsui Breen S-2030, 4 parts;

[0213] Pigment: Titanium white, 2 parts;

[0214] Pigment: Phthalocyanine blue, 0.3 parts;

[0215] Leveling agent: GLP588, 1 part;

[0216] External thixotropic agent: Fumed alumina, 0.2 parts.

[0217] The manufacturing method is the same as Example 1.

[0218] Comparative Example 2

[0219] Epoxy resin one: CYD012, 40 parts;

[0220] Epoxy resin three: YX4000, 2 parts;

[0221] Anhydride-based curing agent: trimellitic anhydride, 7.5 parts;

[0222] Curing accelerator: 2E4MZ-A, 1 part;

[0223] Filler: silicon fine powder, 50 parts;

[0224] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0225] Electricity increasing agent: TEHA triisooctylamine, 1 part;

[0226] Toughening agent: Mitsubishi Mitsui Brun S-2030, 4 parts;

[0227] Pigment: titanium white, 2 parts;

[0228] Pigment: phthalocyanine blue, 0.3 parts;

[0229] Leveling agent: GLP588, 1 part;

[0230] External thixotropic agent: fumed alumina, 0.2 parts.

[0231] The manufacturing method is the same as Example 1.

[0232] Comparative Example 3

[0233] Epoxy resin one: CYD012, 40 parts;

[0234] Epoxy resin two: HP7200, 8 parts;

[0235] Anhydride-based curing agent: trimellitic anhydride, 7.5 parts;

[0236] Curing accelerator: 2E4MZ-A, 1 part;

[0237] Filler: silicon fine powder, 50 parts;

[0238] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0239] Electricity increasing agent: TEHA triisooctylamine, 1 part;

[0240] Toughening agent: Mitsubishi Mitsui Brun S-2030, 4 parts;

[0241] Pigment: titanium white, 2 parts;

[0242] Pigment: Phthalocyanine blue, 0.3 parts;

[0243] Leveling agent: GLP588, 1 part;

[0244] Additional thixotropic agent: fumed alumina, 0.2 parts.

[0245] The manufacturing method is the same as that of Example 1.

[0246] Comparative Example 4

[0247] Epoxy resin 1: CYD012, 40 parts;

[0248] Epoxy resin 2: HP7200, 8 parts;

[0249] Epoxy resin 3: YX4000, 2 parts;

[0250] Anhydride curing agent: trimellitic anhydride, 7.5 parts;

[0251] Curing accelerator: 2E4MZ-A, 1 part;

[0252] Filler: silicon micropowder, 50 parts;

[0253] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0254] Charge enhancer: TEHA triisooctylamine, 1 part;

[0255] Pigment: titanium dioxide, 2 parts;

[0256] Pigment: Phthalocyanine blue, 0.3 parts;

[0257] Leveling agent: GLP588, 1 part;

[0258] Additional thixotropic agent: fumed alumina, 0.2 parts.

[0259] The manufacturing method is the same as that of Example 1.

[0260] Comparative Example 5

[0261] Epoxy resin 1: CYD012, 40 parts;

[0262] Epoxy resin 2: HP7200, 8 parts;

[0263] Epoxy resin 3: YX4000, 2 parts;

[0264] Anhydride curing agent: trimellitic anhydride, 7.5 parts;

[0265] Curing accelerator: 2E4MZ-A, 1 part;

[0266] Filler: silicon micropowder, 50 parts;

[0267] Adhesion promoter: aluminum tripolyphosphate, 3 parts;

[0268] Toughening agent: Mitsubishi-Meghita Buren S-2030, 4 parts;

[0269] Pigment: titanium dioxide, 2 parts;

[0270] Pigment: phthalocyanine blue, 0.3 parts;

[0271] Leveling agent: GLP588, 1 part;

[0272] External thixotropic agent: fumed alumina, 0.2 parts.

[0273] The manufacturing method is the same as Example 1.

[0274] In order to verify the beneficial effects of the invention, relevant test items are carried out.

[0275] The test results of the specific examples and comparative examples are listed in Table 1 and Table 2, respectively.

[0276] The relevant test items and methods of the invention are as follows:

[0277] Powder properties: horizontal flow rate, gelation time, 45 micron laser particle size;

[0278] Powder cycle resistance: electrostatic fluidized bed coating;

[0279] Bar hardness: verify the rapid reactivity of the coating:

[0280] Cured product properties: electrical strength, cured product Tg, cold and hot impact resistance;

[0281] Environmental substances: chlorine element (Cl), bromine element (Br), RoHS 2.0 test items.

[0282] The performance index test methods are as follows:

[0283] (1) Horizontal flow rate: according to 5.1.6 of GB / T 28859-2012 "Epoxy powder coating for electronic components", temperature setting 150±2℃, holding time 30min.

[0284] (2) Gelation time: according to the method in GB / 16995-1997 "Determination of gelation time of thermosetting powder coatings at a given temperature", temperature setting 160±2℃.

[0285] (3) 45 micron laser particle size, according to GBT 19077-2016 "Particle size distribution - Laser diffraction method".

[0286] (4) Electrostatic fluidized bed coating powder cycle resistance.

[0287] (5) Barcol hardness: Silicon steel sheet spraying, coating thickness 0.2-0.4mm, 230℃ / 90s curing, then test the Barcol hardness with Barcol hardness tester.

[0288] (6) Electrical strength: According to GB / T 1408.1-2016 "Insulating materials - Determination of the dielectric strength in liquid", press the test sample with diameter of about 100mm and thickness of about 0.5mm in the mold, 5pcs per group. Test the electrical strength of the cured sample in insulating oil.

[0289] (7) Cured product Tg: According to GB / T 36800.2 "Plastics - Thermomechanical analysis (TMA) - Part 2: Determination of linear thermal expansion coefficient and glass transition temperature", take sample after the coating is cured at 230℃ / 90s, and test with TMA method.

[0290] (8) Cold and hot impact resistance: According to TCSTM 00971 "Thermosetting powder coatings for electrical insulation", tin plate spraying coating thickness 0.18-0.22mm, 200℃ / 1H curing, then test the cold and hot impact resistance from -40±2℃ to + (85±2) ℃ for 10 minutes each, and the conversion time is less than 5 minutes.

[0291] (9) Environmental substances:

[0292] ① Chlorine element (Cl), bromine element (Br), according to IEC 61249-2-21.

[0293] ② RoHS 2.0 test items, according to RoHS 2.0.

[0294] The beneficial effects of the present application are:

[0295] 1. Example 2 vs. Comparative Example 1, after using phenolic hydroxyl curing agent in Comparative Example 1, the reaction speed is slow, which leads to cracking of the coating on the silicon steel sheet after curing at 230℃ / 90s, and the hardness cannot be tested. Therefore, anhydride curing agent with large curing speed and crosslinking density is selected.

[0296] 2. Example 2 vs. Comparative Example 2, Comparative Example 2 removes epoxy resin II, which leads to slow curing speed and low crosslinking density of the cured product after curing at 230℃ / 90s, and the coating cracks and falls off during hardness testing. Therefore, multi-functional epoxy resin is added to increase the crosslinking density and improve the Barcol hardness of the coating.

[0297] 3. Example 2 vs. Comparative Example 3, Comparative Example 3 removed epoxy resin three, resulting in poor adhesion on silicon steel sheet after 230°C / 90 seconds curing, lower crosslinking density of the cured product, cracking and peeling of the coating during hardness testing. Therefore, it is necessary to add a ring-type epoxy to reduce the melt viscosity, improve the wettability of the melt and the micro motor silicon steel sheet, and improve the adhesion.

[0298] 4. Example 2 vs. Comparative Example 4, Comparative Example 4 removed the core-shell toughening agent, resulting in insufficient toughness of the coating on the silicon steel sheet after 230°C / 90 seconds curing, cracking, and cracking of the coating during cold and hot impact resistance testing. Therefore, a core-shell toughening agent is added to resist the damage of stress.

[0299] 5. Example 2 vs. Comparative Example 5, Comparative Example 5 removed the electric enhancer, resulting in poor powder circulation in the electrostatic fluidized bed equipment, which cannot meet the requirements of recycling. Therefore, an electric enhancer is added to improve the consistency of the charging of coarse and fine particles, and to solve the powder circulation problem during electrostatic fluidized bed coating. It is found that the coating becomes thinner after recycling, and the coating parameters need to be adjusted frequently.

[0300] The present application uses the above technical means to prepare an epoxy powder composition for micro motors, which meets the requirements of full-automatic electrostatic fluidized bed coating process for micro motors, can be quickly cured, and the powder can be recycled for stable coating parameters, meets the requirements of halogen-free and RoHS 2.0 environmental protection, the cured product can resist the impact of external stress without cracking, and the cured product has a high Tg to meet the heat resistance requirements. The epoxy powder composition has high market application value and prospect, and is worth further popularization and use.

[0301] Although the embodiments of the present application are disclosed for illustrative purposes, those skilled in the art can understand that various alternatives, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims, therefore, the scope of the present application is not limited to the disclosed content of the embodiments.

[0302] Table 1 Performance test results of examples

[0303]

[0304] Table 2 Performance test results of comparative examples

[0305]

[0306] By comparing and analyzing the above test results, it can be seen that the epoxy powder composition for micro-motor prepared by the method and the ratio of the present application has excellent performance and can meet the market demand for various performances. It can also be seen that the epoxy powder composition for micro-motor of the present application is a multi-component system in which the functions are coordinated and the effects are complementary. The optimization of the components and the ratio is the function and effect that meets the market demand.

[0307] By comparing and analyzing the specific comparison of Example 2 and each comparative example, the function and indispensability of each key component in the system are demonstrated. The use of "elimination method" not only verifies the rationality of the formula design, but also deeply reveals that the failure of each component may lead to the collapse of the overall performance.

[0308] Example 2 and Comparative Example 1 - Kinetics of curing system: anhydride and phenolic resin.

[0309] Comparative Example 1 replaces the anhydride curing agent in Example 2 with a phenolic curing agent, which results in a catastrophic mechanical performance failure. The data shows that the coating of Comparative Example 1 directly cracks in the bar hardness test and cannot measure the effective hardness value. The fundamental reason for this phenomenon is the mismatch of the curing reaction kinetics.

[0310] The gel time of the anhydride system of Example 2 at 160°C is 50 seconds, while the phenolic system of Comparative Example 1 is as long as 70 seconds. In the fast curing process window of 230°C, 90 seconds, this 20-second difference is decisive. The reaction speed of the phenolic resin curing system is relatively slow and cannot reach sufficient crosslinking within 90 seconds. Incomplete curing leads to a loose polymer network structure, weak intermolecular forces, and insufficient 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 propagation of macro cracks, ultimately resulting in brittle cracking of the coating.

[0311] It is worth noting that although the electrical strength of Comparative Example 1 is as high as 52.56KV / mm, far exceeding the 42.8KV / mm of Example 2, this index has no practical significance under the premise of complete mechanical performance failure. An insulating coating that cannot maintain its own structural integrity cannot function in practical applications, no matter how high its electrical performance is. This comparison strongly proves that the reaction kinetics of the formula must be precisely matched with the production process parameters (such as curing temperature and time), which is the primary prerequisite for ensuring that the performance of the final product is achieved.

[0312] Example 2 and Comparative Example 2 - Crosslinking density: the role of multifunctional epoxy resin.

[0313] Comparative Example 2 removed the multi-functional epoxy resin (HP7200) from the baseline formulation, which directly weakened the thermal mechanical stability and structural integrity of the cured product. The most direct evidence is the sharp drop in glass transition temperature (Tg), from 136.2 °C in Example 2 to 108 °C in Comparative Example 2.

[0314] Tg is a core indicator of the thermal stability of amorphous polymers, which is closely related to the crosslinking density of the polymer. Multi-functional epoxy resins (such as phenolic epoxy resins) can form highly branched and crosslinked network structures in the curing reaction due to the multiple epoxy functional groups in their molecular structure. These dense chemical bonds firmly bind polymer segments together, limiting their ability to move when heated, thereby increasing the Tg of the material.

[0315] After removing HP7200, the average functionality of the system decreases, leading to a significant decrease in the density of the crosslinked network formed. This not only significantly reduces the thermal stability of the material (Tg drops by about 28 °C), but also severely weakens its mechanical strength. A network with low crosslinking density lacks both cohesion and rigidity to resist mechanical stress. Therefore, in the bar hardness test, the coating cracks at a lower hardness value (52) and is accompanied by peeling. This shows that HP7200 is not a simple additive, but a core framework that builds the thermal mechanical properties and structural integrity of the formulation.

[0316] Example 2 vs. Comparative Example 3 - Interface and Rheology: The Function of Crystalline Epoxy Resin.

[0317] Comparative Example 3 removed the crystalline epoxy resin (YX4000), resulting in cracking (hardness 55) and peeling of the coating in the hardness test. This failure mode reveals that the final performance of the coating depends not only on the mechanical properties of its bulk, but also on the interfacial bonding strength between it and the substrate.

[0318] The role of the crystalline epoxy resin in the formulation is twofold. At the curing temperature (such as 230 °C), its crystal structure melts, significantly reducing the viscosity of the entire molten system. According to the Wenzel and Cassie-Baxter models, lower melt viscosity facilitates the full spreading and penetration of the melt on 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 basis for forming a strong mechanical anchoring effect.

[0319] When YX4000 was removed, the system had relatively high melt viscosity and poor flowability. Within the limited curing time, the melt could not sufficiently wet the substrate, resulting in a weakly bonded interface between the coating and the metal substrate. Although the coating body after curing might have certain hardness, under the local high stress of the hardness test, the weak interface became a stress concentration point, cracks were easily initiated and propagated along the interface, eventually leading to coating cracking and peeling from the substrate. This case clearly shows that for coating applications, optimizing the interface performance is as important as optimizing the bulk performance.

[0320] Example 2 vs. Comparative Example 4 - Toughness: the role of core-shell toughener.

[0321] Comparative Example 4 removed the core-shell toughener (S-2030) while retaining high Tg (137.4°C) and high hardness (65). As a result, the coating cracked during the hardness test and completely failed (NG) in the more severe cold-heat shock resistance test. This result perfectly illustrates the key role of toughness in high crosslinking density epoxy systems.

[0322] High crosslinking density epoxy resin is essentially a hard and brittle material. Its rigid network structure, while providing high hardness and high Tg, also makes it almost unable to deform when subjected to impact or stress, and energy cannot be effectively absorbed, leading to rapid crack propagation. The introduction of core-shell toughener disperses a large number of nanoscale "soft" phases in the rigid epoxy matrix. This toughener usually has a rubbery core (such as polybutadiene or acrylate) and a shell that is well compatible with the epoxy matrix.

[0323] When the material is subjected to stress, these nanoscale soft cores act as stress concentration points, causing local yielding and shear band formation of the matrix, or absorbing and dissipating energy through their own cavitation, thus effectively preventing microcracks from developing into catastrophic macroscopic fractures. In the hardness test, even though the hardness value is high, Comparative Example 4 without the toughener still cracks, indicating a lack of damage tolerance. The cold-heat shock resistance test magnifies this weakness: in the severe temperature cycle from -40°C to 85°C, the coating and the metal substrate generate a large internal stress due to the mismatch of the coefficient of thermal expansion (CTE). For brittle materials, this internal stress is enough to cause cracking. The failure of Comparative Example 4 in this test most directly proves the irreplaceability of the core-shell toughener in giving the coating resistance to thermal stress and mechanical impact, ensuring long-term service reliability.

[0324] Example 2 vs. Comparative Example 5 - Process stability: the role of energizer.

[0325] 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.

[0326] 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.

[0327] 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.

[0328] 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.

[0329] 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.

[0330] 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; The third epoxy resin is a crystalline epoxy resin containing a biphenyl structure, a sulfide structure, a phenylene structure, or a naphthalene structure, one or more of which are selected; The adhesion promoter is one or more of aluminum tripolyphosphate, modified aluminum tripolyphosphate, and aluminum dihydrogen tripolyphosphate; 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 charge enhancer is one or more of hindered amine compounds, alkanolamine compounds, quaternary ammonium salts, imidazoline compounds, polar fatty acid esters or metal salts of polar fatty acid esters; After the epoxy powder composition for micro motor is cured, the coating has a Barcol hardness of ≥50 and no cracks; The epoxy powder composition for micro motors can be normally coated for more than 12 hours in an electrostatic fluidized bed coating production line.

2. The epoxy powder composition for micro motor according to claim 1, characterized in that: Glass transition temperature ≥110℃, electrical strength ≥30kV / mm, thermal shock resistance ≥500 times, chlorine content ≤900ppm, bromine content ≤900ppm, total content of chlorine and bromine ≤1500ppm.

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, and dicyclopentadiene epoxy resin.

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 powder, mica powder, calcium silicate, zirconium silicate, calcium carbonate, barium sulfate, kaolin, montmorillonite, aluminum oxide, aluminum hydroxide, and boehmite.

6. The epoxy powder composition for micro motor according to claim 1, characterized in that: The pigment is one or more of rutile titanium dioxide, anatase titanium dioxide, phthalocyanine blue, iron oxide red, iron oxide yellow, organic yellow pigment, organic red pigment, organic orange pigment, 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 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.

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