Thermosetting insulating thin-coating encapsulating material for replacing paint in electronic industry

Abstract

The invention discloses a thermosetting insulating thin-coating encapsulating material for the electronic industry, and belongs to the technical field of insulating encapsulating materials, a modified curing agent in the raw materials of the encapsulating material is prepared from furan derivatives containing siloxy and maleic anhydride through Diels-Alder reaction; the accelerator is an isocyanate modified imidazole compound, the modified curing agent and the accelerator can be stably stored at normal temperature, acid anhydride and imidazole groups can be protected at normal temperature, the modified curing agent and the accelerator do not need to be prepared at present, the applicability is good, and the cost is low. Imidazole, isocyanate and anhydride compounds capable of participating in curing are formed through reverse reaction and decomposition in the high-temperature curing process and act together with tris (hydroxymethyl) aminomethane, multiple curing reactions are carried out synchronously, the curing process is promoted synergistically, and the curing speed is increased.

Description

Technical Field

[0001] The invention belongs to the technical field of insulating encapsulating materials, and in particular relates to a thermosetting insulating thin coating encapsulating material used in the electronics industry to replace paint. Background Art

[0002] Epoxy resin insulating thin coating encapsulation material is an important electronic packaging material, which is widely used in the field of insulating packaging of electronic components.

[0003] Epoxy resin insulation materials have good insulation performance, heat resistance, moisture resistance and mechanical strength. They can effectively protect electronic components from the influence of the external environment and extend their service life. They are used for the outer packaging of electronic components such as varistors, thermistors, ceramic capacitors, film capacitors, monolithic capacitors, resettable fuses, magnetic rings, etc., and can play the role of insulation protection. Because they do not contain any solvents, are pollution-free, have high utilization rates, low energy consumption, high production efficiency, excellent coating properties, and the encapsulation materials can be recycled and reused, the epoxy insulation thin coating encapsulation material has a thin coating after curing, low water absorption, good impact resistance, no VOC emissions, and excellent surface adhesion and hardness.

[0004] At present, insulation encapsulation materials are divided into two categories: thermosetting epoxy insulation thin coating encapsulation materials and thermosetting thin coatings. The curing temperature of existing thermosetting thin coatings is usually around 150°C, which is high and slow, and is not conducive to improving coating efficiency. Therefore, under the premise of ensuring the coating effect, developing a fast-curing thermosetting thin coating for coating on electronic components is a technical problem that needs to be solved in the industry. Summary of the invention

[0005] The purpose of the present invention is to provide a thermosetting insulating thin coating encapsulation material for replacing paint in the electronics industry, thereby accelerating the curing speed and improving the coating efficiency.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] The present invention provides a thermosetting insulating thin coating encapsulation material for the electronics industry, which comprises the following raw materials in parts by mass:

[0008] 500-550 parts of special epoxy resin, 20-40 parts of modified curing agent, 10-20 parts of accelerator, 50-66 parts of tris(hydroxymethyl)aminomethane, 10-20 parts of reactive diluent, 5-10 parts of polyethylene wax, 50-100 parts of silica powder, 50-100 parts of alumina, and 10-20 parts of pigment;

[0009] The modified curing agent is prepared by a furan derivative containing a silyl group and maleic anhydride through a Diels-Alder reaction; and the accelerator is an isocyanate-modified imidazole compound.

[0010] The product of the Diels-Alder reaction is reversible at high temperature. Furan derivatives, as conjugated diene reactants, react with maleic anhydride to generate cross-linked polymers. The polymer will reversely react under high temperature conditions and reduce to the reactant structure to participate in the curing reaction. Acid anhydrides are often used as curing agents for epoxy resins, but acid anhydrides easily absorb moisture in the air and react to generate free acids, thereby hindering the subsequent curing reaction. Through the Diels-Alder reaction, acid anhydrides exist in the form of cross-linked polymers at room temperature. The introduced aromatic rings and siloxanes are used to improve the hydrophobicity of the modified curing agent, protect the acid anhydride groups, and improve the curing effect. At the same time, the introduced siloxanes can be adsorbed on the surface of inorganic materials (silicon powder and alumina) through hydrogen bonding, and the steric hindrance formed by the aromatic rings can be used to prevent the aggregation between particles and promote the dispersion of inorganic materials.

[0011] Isocyanate-modified imidazole compounds utilize the reaction between isocyanate and secondary amine on the imidazole ring to block the activity of the secondary amine of imidazole. Imidazole compounds contain secondary amine groups, which can react with the epoxy group of epoxy resin to achieve the purpose of curing. However, the chemical properties of imidazole curing agents are relatively active and are easy to volatilize at high temperatures, resulting in reduced curing effect. Through isocyanate blocking, it will only decompose into isocyanate and imidazole when the high temperature unblocking temperature is reached, avoiding the failure of the curing component of the epoxy resin encapsulation material before high temperature curing.

[0012] When the modified curing agent, accelerator and tris(hydroxymethyl)aminomethane are used in combination, the acid anhydride, imidazole and isocyanate produced by high temperature decomposition will participate in the curing reaction of the epoxy resin. There are multiple curing reactions. The acid anhydride reacts with a small amount of hydroxyl groups on the epoxy resin to open the acid anhydride ring, and the formed carboxyl group reacts with the epoxy group to open the ring. Imidazole can be used as an accelerator to promote the acid anhydride to form carboxylic acid anions to open the epoxy group, forming ester groups and oxygen anions, and the continuous reaction achieves the effect of cross-linking and curing. The tertiary nitrogen atom of imidazole acts as an anionic polymerization catalyst to promote the ring-opening polymerization reaction of the epoxy group, thereby forming a cured product with a network structure. Isocyanate reacts with the epoxy group to form a hydroxyl group to form a three-dimensional cross-linked structure. There are abundant hydroxyl and amino groups in tris(hydroxymethyl)aminomethane, and its amino group can react with the epoxy group to enhance the cross-linking density. The abundant hydroxyl groups can promote the dispersion of inorganic materials in the epoxy resin. Under the condition that multiple curing reactions exist at the same time, they promote each other, accelerate the curing process, and shorten the curing time.

[0013] Furthermore, the epoxy equivalent of the special epoxy resin is 200-300 g / eq. The epoxy equivalent of epoxy resin affects the reaction degree between epoxy resin and curing agent. The larger the epoxy equivalent, the longer the molecular chain, and the higher the viscosity. When the epoxy equivalent is small, the molecular chain is short and the viscosity is low. A higher epoxy equivalent indicates that the molecule contains more epoxy groups, thereby increasing the activity and rate of the curing reaction. However, too high an epoxy equivalent may lead to an increase in the brittleness of the cured product and a decrease in flexibility. Therefore, an epoxy resin with an appropriate epoxy equivalent is selected.

[0014] Furthermore, the special epoxy resin is at least one of o-cresol novolac epoxy resin, dicyclopentadiene phenol epoxy resin, and phenol biphenyl epoxy resin.

[0015] Furthermore, the preparation steps of the modified curing agent are as follows:

[0016] Mix trimethylsilyloxy-2-furan and maleic anhydride in a molar ratio of 4-5:1, stir and react at room temperature for 8-12 h. After the reaction, filter by suction, wash the solid product with absolute ethanol, and dry to obtain the modified curing agent.

[0017] Furthermore, the structural formula of the modified curing agent is as follows:

[0018]

[0019] The reaction route of the above preparation is as follows:

[0020]

[0021] Furthermore, the preparation steps of the accelerator are as follows:

[0022] Dissolve the imidazole compound in an organic solvent to form a 1.6-2 mol / L imidazole solution, dissolve the isocyanate in an organic solvent to form a 0.8-1 mol / L isocyanate solution, heat the imidazole solution in a water bath to 60-80 °C, and according to the number ratio of secondary amine and isocyanate group on the imidazole ring of 1-1.2:1, add the isocyanate solution dropwise to the imidazole solution. After the addition, react at a constant temperature for 3-4 h, and evaporate to remove the solvent to obtain the accelerator.

[0023] Furthermore, the imidazole compound is one of 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-isopropylimidazole.

[0024] Furthermore, the isocyanate is one of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and diphenylmethane diisocyanate.

[0025] Furthermore, the organic solvent is one of chloroform and N,N-dimethylformamide

[0026] The reaction route for the above preparation is as follows (taking 2-methylimidazole and hexamethylene diisocyanate as examples):

[0027]

[0028] Furthermore, the active diluent is one of C12-14 alkyl glycidyl ether and butyl glycidyl ether. The active diluent can reduce the viscosity of the epoxy resin, improve the fluidity of the coating after melting, and promote the formation of a thin layer coating.

[0029] Furthermore, the particle size of the silica powder is 0.1 - 0.5 μm, and the particle size of the alumina is 1 - 10 μm. As cost-effective inorganic materials, silica powder and alumina can improve the wear resistance and heat resistance of the material.

[0030] Furthermore, the preparation steps of the thermosetting insulating thin coating encapsulation material are as follows:

[0031] Step 1: Pour the raw materials into the mixing tank according to the ratio and stir evenly. Set the temperature of the melting section I of the twin-screw extruder to 70 - 80 °C, and the temperature of section II to 60 - 70 °C, and melt and extrude the materials through the twin-screw extruder.

[0032] Step 2: Press the cooled material into a thin sheet with a thickness of 0.5 - 1.5 mm. Crush, grind, and filter the thin sheet through a 250 - 300 mesh sieve to obtain the thermosetting insulating thin coating encapsulation material.

[0033] Advantages of the present invention:

[0034] (1) In the present invention, a modified curing agent, a promoter, and tris(hydroxymethyl)aminomethane act together to promote the curing of the epoxy resin. By utilizing the synergistic effect of different groups in the reaction with the epoxy group, the curing reaction process is accelerated, the curing speed is fast, and the coating efficiency is improved.

[0035] (2) The modified curing agent in the present invention is prepared by the Diels-Alder reaction of a furan derivative containing a siloxy group and maleic anhydride, and the promoter is an isocyanate-modified imidazole compound. By using the Diels-Alder reaction and the blocking reaction of isocyanate, the acid anhydride and imidazole groups are protected at room temperature, and the high-temperature decomposition and reverse reaction products participate in the curing reaction, so that the modified curing agent and the promoter do not need to be prepared immediately before use, have good applicability, and have excellent curing effects.

[0036] (3) In the present invention, silica powder and alumina are added as fillers to improve the wear resistance and heat resistance of the encapsulation material. A modified curing agent introducing siloxy groups and aromatic rings and tris(hydroxymethyl)aminomethane are used to promote the dispersion of inorganic materials in the resin system, avoiding the addition of coupling agents; and an active diluent is added to the raw materials to reduce the viscosity of the material after melting, increase the fluidity, and facilitate the formation of a flat thin layer coating. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] Preparation of modified curing agent:

[0040] Trimethylsilyloxy-2-furan and maleic anhydride were mixed in a molar ratio of 4:1, stirred and reacted at room temperature for 12 hours, and filtered after the reaction. The solid product was washed with anhydrous ethanol and dried at 60°C to obtain a modified curing agent.

[0041] Preparation of accelerator:

[0042] Dissolve 2-methylimidazole in chloroform to form a 2 mol / L imidazole solution, and dissolve hexamethylene diisocyanate in chloroform to form a 1 mol / L isocyanate solution. Heat the imidazole solution to 80°C in a water bath, and add the isocyanate solution dropwise to the imidazole solution in a ratio of 1.2:1 between the secondary amine and isocyanate groups on the imidazole ring. After the addition is completed, keep the reaction at a constant temperature for 4 hours, and evaporate the solvent to obtain the accelerator.

[0043] Preparation of thermosetting insulating thin coating encapsulation material:

[0044] Step 1: Prepare the following raw materials by weight:

[0045] 500 parts of o-cresol epoxy resin (epoxy equivalent is 200-210g / eq), 30 parts of modified curing agent, 10 parts of accelerator, 50 parts of trishydroxymethylaminomethane, 10 parts of C12-14 alkyl glycidyl ether, 5 parts of polyethylene wax, 50 parts of silicon micropowder (particle size is 0.1-0.5μm), 50 parts of aluminum oxide (particle size is 1-10μm), and 10 parts of titanium dioxide;

[0046] Pour the raw materials into a mixing tank according to the above ratio and stir evenly, set the temperature of zone I of the twin-screw extruder melting section to 70-80°C, and the temperature of zone II to 60-70°C, and melt and extrude the materials through the twin-screw extruder.

[0047] Step 2: After the material is cooled, it is pressed into thin sheets with a thickness of 0.5-1.5 mm. The thin sheets are crushed, ground and filtered through a 300-mesh screen to obtain a thermosetting insulating thin coating encapsulation material.

[0048] Example 2

[0049] The only difference from Example 1 is that the special epoxy resin in the raw material adopts dicyclopentadiene phenol epoxy resin (epoxy equivalent is 235-255g / eq), and the preparation steps of the thermosetting insulating thin coating encapsulation material are as follows. Other conditions and steps are the same as Example 1.

[0050] Step 1: Prepare the following raw materials by weight:

[0051] 500 parts of dicyclopentadiene phenol epoxy resin (epoxy equivalent is 235-255g / eq), 30 parts of modified curing agent, 10 parts of accelerator, 50 parts of trishydroxymethylaminomethane, 10 parts of C12-14 alkyl glycidyl ether, 5-10 parts of polyethylene wax, 50 parts of silicon micropowder (particle size is 0.1-0.5μm), 50 parts of aluminum oxide (particle size is 1-10μm), and 10 parts of titanium dioxide;

[0052] Pour the raw materials into a mixing tank according to the above ratio and stir evenly, set the temperature of zone I of the twin-screw extruder melting section to 70-80°C, and the temperature of zone II to 60-70°C, and melt and extrude the materials through the twin-screw extruder.

[0053] Step 2: After the material is cooled, it is pressed into thin sheets with a thickness of 0.5-1.5 mm. The thin sheets are crushed, ground and filtered through a 300-mesh screen to obtain a thermosetting insulating thin coating encapsulation material.

[0054] Example 3

[0055] The only difference from Example 1 is that the special epoxy resin in the raw material adopts phenol biphenyl epoxy resin (epoxy equivalent is 261-282g / eq), and the preparation steps of the thermosetting insulating thin coating encapsulation material are as follows. Other conditions and steps are the same as Example 1.

[0056] Step 1: Prepare the following raw materials by weight:

[0057] 500 parts of phenol biphenyl epoxy resin (epoxy equivalent is 261-282g / eq), 30 parts of modified curing agent, 10 parts of accelerator, 50 parts of trishydroxymethylaminomethane, 10 parts of C12-14 alkyl glycidyl ether, 5-10 parts of polyethylene wax, 50 parts of silicon micropowder (particle size is 0.1-0.5μm), 50 parts of aluminum oxide (particle size is 1-10μm), and 10 parts of titanium dioxide;

[0058] Pour the raw materials into a mixing tank according to the above ratio and stir evenly, set the temperature of zone I of the twin-screw extruder melting section to 70-80°C, and the temperature of zone II to 60-70°C, and melt and extrude the materials through the twin-screw extruder.

[0059] Step 2: After the material is cooled, it is pressed into thin sheets with a thickness of 0.5-1.5 mm. The thin sheets are crushed, ground and filtered through a 300-mesh screen to obtain a thermosetting insulating thin coating encapsulation material.

[0060] Example 4

[0061] The difference from Example 1 is only that 2-ethyl-4-methylimidazole is used to replace 2-methylimidazole for preparing the accelerator. The steps for preparing the accelerator are as follows, and other conditions and steps are the same as those in Example 1.

[0062] Dissolve 2-ethyl-4-methylimidazole in chloroform to form a 2 mol / L imidazole solution, dissolve hexamethylene diisocyanate in chloroform to form a 1 mol / L isocyanate solution, heat the imidazole solution to 80 °C in a water bath, and add the isocyanate solution dropwise to the imidazole solution according to the molar ratio of secondary amine to isocyanate group on the imidazole ring of 1.2:1. After the addition is completed, react at a constant temperature for 4 h, and evaporate to remove the solvent to obtain the accelerator.

[0063] Example 5

[0064] The difference from Example 1 is only that 2-isopropylimidazole is used to replace 2-methylimidazole for preparing the accelerator. The steps for preparing the accelerator are as follows, and other conditions and steps are the same as those in Example 1.

[0065] Dissolve 2-isopropylimidazole in chloroform to form a 2 mol / L imidazole solution, dissolve hexamethylene diisocyanate in chloroform to form a 1 mol / L isocyanate solution, heat the imidazole solution to 80 °C in a water bath, and add the isocyanate solution dropwise to the imidazole solution according to the molar ratio of secondary amine to isocyanate group on the imidazole ring of 1.2:1. After the addition is completed, react at a constant temperature for 4 h, and evaporate to remove the solvent to obtain the accelerator.

[0066] Example 6

[0067] The difference from Example 1 is only that trimethylhexamethylene diisocyanate is used to replace hexamethylene diisocyanate for preparing the accelerator. The steps for preparing the accelerator are as follows, and other conditions and steps are the same as those in Example 1.

[0068] Dissolve 2-methylimidazole in chloroform to form a 2 mol / L imidazole solution, dissolve trimethylhexamethylene diisocyanate in chloroform to form a 1 mol / L isocyanate solution, heat the imidazole solution to 80 °C in a water bath, and add the isocyanate solution dropwise to the imidazole solution according to the molar ratio of secondary amine to isocyanate group on the imidazole ring of 1.2:1. After the addition is completed, react at a constant temperature for 4 h, and evaporate to remove the solvent to obtain the accelerator.

[0069] Example 7

[0070] The difference from Example 1 is only that diphenylmethane diisocyanate is used to replace hexamethylene diisocyanate for preparing the accelerator, and other conditions and steps are the same as those in Example 1.

[0071] Dissolve 2-methylimidazole in chloroform to form a 2 mol / L imidazole solution, dissolve diphenylmethane diisocyanate in N,N-dimethylformamide (DMF) to form a 1 mol / L isocyanate solution, heat the imidazole solution to 80 °C in a water bath, and add the isocyanate solution dropwise to the imidazole solution according to the molar ratio of secondary amine to isocyanate group on the imidazole ring of 1.2:1. After the addition is completed, react at a constant temperature for 4 h, and evaporate to remove the solvent to obtain the accelerator.

[0072] Example 8

[0073] The difference from Example 1 is only that the raw material ratio is different. The mass ratio of the modified curing agent to the accelerator is controlled to be 5:3, and other conditions and steps are the same as those in Example 1. The specific ratio is as follows:

[0074] 500 parts of o-cresol novolac epoxy resin (epoxy equivalent 200 - 210 g / eq), 25 parts of modified curing agent, 15 parts of accelerator, 50 parts of tris(hydroxymethyl)aminomethane, 10 parts of C12-14 alkyl glycidyl ether, 5 parts of polyethylene wax, 50 parts of silica powder (particle size 0.1 - 0.5 μm), 50 parts of alumina (particle size 1 - 10 μm), 10 parts of titanium dioxide.

[0075] Example 9

[0076] The difference from Example 1 is only that the raw material ratio is different. The mass ratio of the modified curing agent to the accelerator is controlled to be 1:1, and other conditions and steps are the same as those in Example 1. The specific ratio is as follows:

[0077] 500 parts of o-cresol novolac epoxy resin (epoxy equivalent 200 - 210 g / eq), 20 parts of modified curing agent, 20 parts of accelerator, 50 parts of tris(hydroxymethyl)aminomethane, 10 parts of C12-14 alkyl glycidyl ether, 5 parts of polyethylene wax, 50 parts of silica powder (particle size 0.1 - 0.5 μm), 50 parts of alumina (particle size 1 - 10 μm), 10 parts of titanium dioxide.

[0078] Example 10

[0079] The difference from Example 8 is only that the raw material ratio is different. The mass fraction of tris(hydroxymethyl)aminomethane is adjusted to 55 parts, and other conditions and steps are the same as those in Example 8.

[0080] Example 11

[0081] The difference from Example 8 is only that the raw material ratio is different. The mass fraction of tris(hydroxymethyl)aminomethane is adjusted to 60 parts, and other conditions and steps are the same as those in Example 8.

[0082] Comparative Example 1

[0083] The difference from Example 1 is only that the accelerator is replaced with an equal mass of modified curing agent in the raw materials.

[0084] Preparation of modified curing agent:

[0085] Mix trimethylsilyloxy-2-furan and maleic anhydride in a molar ratio of 4:1, stir and react at room temperature for 12 h. After the reaction, filter by suction. Wash the solid product with absolute ethanol and dry at 60 °C to obtain the modified curing agent.

[0086] Preparation of thermosetting insulating thin coating encapsulation material:

[0087] Step 1: Prepare the following raw materials by mass parts:

[0088] 500 parts of o-cresol novolac epoxy resin (epoxy equivalent: 200 - 210 g / eq), 40 parts of modified curing agent, 50 parts of tris(hydroxymethyl)aminomethane, 10 parts of C12-14 alkyl glycidyl ether, 5 parts of polyethylene wax, 50 parts of silica powder (particle size: 0.1 - 0.5 μm), 50 parts of alumina (particle size: 1 - 10 μm), 10 parts of titanium dioxide;

[0089] Pour the raw materials into a mixing tank according to the above ratio and stir evenly. Set the temperature of the melting section I of the twin-screw extruder to 70 - 80 °C and the temperature of section II to 60 - 70 °C, and melt and extrude the materials through the twin-screw extruder.

[0090] Step 2: After the materials are cooled, press them into thin sheets with a thickness of 0.5 - 1.5 mm. Crush, grind the thin sheets and filter them through a 300-mesh sieve to obtain the thermosetting insulating thin coating encapsulation material.

[0091] Comparative Example 2

[0092] The difference from Example 1 is only that the modified curing agent in the raw materials is replaced with an accelerator of equal mass.

[0093] Preparation of accelerator:

[0094] Dissolve 2-methylimidazole in chloroform to form a 2 mol / L imidazole solution, and dissolve hexamethylene diisocyanate in chloroform to form a 1 mol / L isocyanate solution. Heat the imidazole solution to 80 °C in a water bath. According to the molar ratio of secondary amine to isocyanate group on the imidazole ring of 1.2:1, add the isocyanate solution dropwise to the imidazole solution. After the addition, react at a constant temperature for 4 h, and evaporate to remove the solvent to obtain the accelerator.

[0095] Preparation of thermosetting insulating thin coating encapsulation material:

[0096] Step 1: Prepare the following raw materials by mass parts:

[0097] 500 parts of o-cresol novolac epoxy resin (epoxy equivalent: 200 - 210 g / eq), 40 parts of accelerator, 50 parts of tris(hydroxymethyl)aminomethane, 10 parts of C12 - 14 alkyl glycidyl ether, 5 parts of polyethylene wax, 50 parts of silica powder (particle size: 0.1 - 0.5 μm), 50 parts of alumina (particle size: 1 - 10 μm), 10 parts of titanium dioxide;

[0098] Pour the raw materials into a mixing tank according to the above ratios and stir evenly. Set the temperature of the melting zone I of the twin-screw extruder to 70 - 80 °C and the temperature of zone II to 60 - 70 °C, and melt and extrude the materials through the twin-screw extruder.

[0099] Step 2: After the material is cooled, press it into a thin sheet with a thickness of 0.5 - 1.5 mm. The thin sheet is crushed, ground, and filtered through a 300-mesh sieve to obtain a thermosetting insulating thin coating encapsulation material.

[0100] Comparative Example 3

[0101] The difference from Example 1 is only that tris(hydroxyethyl)aminomethane is replaced with a modified curing agent and an accelerator in the raw materials.

[0102] Prepare the modified curing agent:

[0103] Mix trimethylsilyloxy-2-furan and maleic anhydride in a molar ratio of 4:1, stir and react at room temperature for 12 h. After the reaction, filter by suction, wash the solid product with absolute ethanol, and dry at 60 °C to obtain the modified curing agent.

[0104] Prepare the accelerator:

[0105] Dissolve 2-methylimidazole in chloroform to form a 2 mol / L imidazole solution, and dissolve hexamethylene diisocyanate in chloroform to form a 1 mol / L isocyanate solution. Heat the imidazole solution to 80 °C in a water bath. According to the molar ratio of secondary amine to isocyanate group on the imidazole ring of 1.2:1, dropwise add the isocyanate solution to the imidazole solution. After the addition, react at a constant temperature for 4 h, and evaporate to remove the solvent to obtain the accelerator.

[0106] Prepare the thermosetting insulating thin coating encapsulation material:

[0107] Step 1: By mass, prepare the following raw materials:

[0108] 500 parts of o-cresol novolac epoxy resin (epoxy equivalent: 200 - 210 g / eq), 67.5 parts of modified curing agent, 22.5 parts of accelerator, 10 parts of C12 - 14 alkyl glycidyl ether, 5 parts of polyethylene wax, 50 parts of silica powder (particle size: 0.1 - 0.5 μm), 50 parts of alumina (particle size: 1 - 10 μm), 10 parts of titanium dioxide;

[0109] Pour the raw materials into the mixing tank according to the above ratios and stir evenly. Set the temperature of the melting zone I of the twin-screw extruder to 70-80 °C and the temperature of zone II to 60-70 °C, and melt and extrude the materials through the twin-screw extruder.

[0110] Step 2: After the material is cooled, press it into a thin sheet with a thickness of 0.5-1.5 mm. The thin sheet is crushed, ground, and filtered through a 300-mesh sieve to obtain a thermosetting insulating thin coating encapsulation material.

[0111] The materials prepared in Examples 1-11 and Comparative Examples 1-3 are coated on the surface of electronic components by electrostatic spraying, and then melted and leveled by high-frequency baking to form a cured film. The results of performance tests are shown in Table 1.

[0112] The adhesion detection refers to the standard of "GBT 9286-2021 Paints and varnishes - Cross-cut test".

[0113] The abrasion resistance detection refers to "GB / T 1768-2006 Paints and varnishes - Determination of abrasion resistance - Rotating rubber wheel method"

[0114] Table 1

[0115]

[0116] As can be seen from Table 1, the thermosetting insulating thin coating encapsulation material prepared in the examples of the present invention has a fast spraying and curing speed on the surface of electronic components, can significantly improve the coating efficiency in actual applications, and its abrasion resistance and adhesion are more excellent than those of the comparative examples, and a flat thin layer coating can be formed on the surface of electronic components.

[0117] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variation thereof are intended to cover a non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0118] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A thermosetting insulating thin coating encapsulation material for the electronics industry, characterized in that, By mass parts, it includes the following raw materials: 500 - 550 parts of special epoxy resin, 20 - 40 parts of modified curing agent, 10 - 20 parts of accelerator, 50 - 66 parts of tris(hydroxymethyl)aminomethane, 10 - 20 parts of reactive diluent, 5 - 10 parts of polyethylene wax, 50 - 100 parts of silica powder, 50 - 100 parts of alumina, 10 - 20 parts of pigment; The modified curing agent is prepared by the Diels - Alder reaction of a furan derivative containing a siloxy group and maleic anhydride; the accelerator is an isocyanate - modified imidazole compound.

2. The thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, wherein The epoxy equivalent of the special epoxy resin is 200 - 300 g / eq; The special epoxy resin is at least one of o - cresol novolac epoxy resin, dicyclopentadiene phenol epoxy resin, and phenol - biphenyl epoxy resin.

3. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, characterized in that, The preparation steps of the modified curing agent are as follows: Mix trimethylsilyloxy - 2 - furan and maleic anhydride in a molar ratio of 4 - 5:1, stir and react at room temperature for 8 - 12 h. After the reaction, filter by suction, wash the solid product with absolute ethanol, and dry to obtain the modified curing agent.

4. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, wherein The structural formula of the modified curing agent is as follows:

5. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, characterized in that, The preparation steps of the accelerator are as follows: Dissolve the imidazole compound in an organic solvent to form a 1.6 - 2 mol / L imidazole solution, dissolve the isocyanate in an organic solvent to form a 0.8 - 1 mol / L isocyanate solution, heat the imidazole solution in a water bath to 60 - 80 °C, and add the isocyanate solution dropwise to the imidazole solution according to the molar ratio of secondary amine and isocyanate group on the imidazole ring of 1 - 1.2:

1. After the dropwise addition, react at a constant temperature for 3 - 4 h, and evaporate to remove the solvent to obtain the accelerator.

6. The thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 5, characterized in that, The imidazole compound is one of 2 - methylimidazole, 2 - ethyl - 4 - methylimidazole, and 2 - isopropylimidazole.

7. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 5, characterized in that, The isocyanate is one of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and diphenylmethane diisocyanate.

8. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, characterized in that, The reactive diluent is one of C12 - 14 alkyl glycidyl ether and butyl glycidyl ether.

9. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, characterized in that, The particle size of the silica powder is 0.1 - 0.5 μm, and the particle size of the alumina is 1 - 10 μm.

10. A thermosetting insulating thin coating encapsulation material for the electronics industry according to claim 1, characterized in that, The preparation steps of the thermosetting insulating thin coating encapsulation material are as follows: Step 1: Pour the raw materials into a mixing tank according to the ratio and stir evenly. Set the temperature of the melting section I of the twin - screw extruder to 70 - 80 °C and the temperature of section II to 60 - 70 °C, and melt - extrude the materials through the twin - screw extruder; Step 2: After the materials are cooled, press them into thin sheets with a thickness of 0.5 - 1.5 mm. The thin sheets are crushed, ground, and filtered through a 250 - 300 - mesh sieve to obtain the thermosetting insulating thin coating encapsulation material.

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