Degradable epoxy resin precursor, insulating material composition and application

Abstract

The invention discloses a degradable epoxy resin precursor. The structure of the degradable epoxy resin precursor is shown as a formula (I) to a formula (III). Polyhydroxy benzaldehyde from a bio-based source is used as a raw material, a tri-functionality acetal type degradable epoxy resin precursor is developed, and an acetal structure can be hydrolyzed under an acidic condition, so that the epoxy resin material is endowed with good degradation performance. In the curing process, a side epoxy group is subjected to a ring-opening reaction and forms a highly-crosslinked network structure with a curing agent, and the special crosslinked structure endows a cured product with excellent thermal stability and mechanical properties, is suitable for supporting, insulation and sealing of electrical equipment, and provides a new way for green and sustainable development of electrical insulation equipment. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the technical field of degradable epoxy resins, and specifically relates to a degradable epoxy resin precursor, an insulating material composition and applications thereof. Background Art

[0002] Epoxy resins have excellent thermal stability, creep resistance, electrical insulation, chemical stability and mechanical properties, and are crucial basic raw materials in the manufacturing of advanced power equipment and electronic packaging fields. However, since epoxy resins react with curing agents to form a structurally stable three-dimensional crosslinked network, it is difficult to recycle and reuse electrical equipment and electronic devices after retirement.

[0003] In recent years, it has been found that the degradation of epoxy resins under specific stimuli (including heating, light, pH and catalysts) can be achieved based on dynamic covalent chemistry, enabling the repeated processing and self-healing of materials. Inspired by this, domestic and foreign scholars have introduced dynamic covalent bonds into the epoxy resin crosslinked network to prepare a series of new materials with excellent degradation properties (Peng Lei, et al. Research progress on environmentally friendly epoxy resin materials [J]. Insulating Materials, 2024, 57(08): 1-16. doi: 10.16790 / j.cnki.1009-9239.im.2024.08.001). The acetal structure is formed by the condensation reaction of aldehydes and alcohols. Compared with other degradable structures, the acetal structure is more unstable under acidic conditions and can be hydrolyzed into corresponding aldehydes and alcohols in a weakly acidic aqueous solution. Moreover, studies have confirmed that the introduction of acetal bonds neither affects the curing of epoxy resins nor impairs the original mechanical properties of the resin (Ma Songqi, et al. Readily recyclable, high-performance thermosetting materials based on alignin-derived spiro diacetal trigger. Journal of Materials Chemistry A, 2019, 7(3): 1233-1243. doi: 10.1039 / C8TA07140C.). However, the acetal structure belongs to a reversible dynamic bond structure, and its anhydride-based cured products have a lower glass transition temperature than those of traditional bisphenol A epoxy resin cured products due to the lower bond energy of the dynamic bonds, which limits its application in the fields of electrical equipment and electronic packaging. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a trifunctional degradable epoxy resin precursor, which has good degradation properties, and the glass transition temperature after curing is higher than that of a difunctional epoxy resin precursor, simultaneously improving the thermal performance and insulation performance and broadening the application scope.

[0005] A degradable epoxy resin precursor has a structure as shown in Formula (Ⅰ) - Formula (Ⅲ):

[0006]

[0007] Wherein, R is the connection position.

[0008] In the present invention, the trifunctional acetal - type degradable epoxy resin precursor can maintain a stable structure under non - acidic conditions, while under acidic conditions, it can undergo a reverse reaction and hydrolyze into aldehydes and alcohols. Therefore, the acetal structure can endow the epoxy resin precursor with good degradation performance. During the curing process, the side - chain epoxy functional groups of the trifunctional epoxy precursor can react with the curing agent, resulting in an increase in the cross - linking degree of the cured product's cross - linked network, making the mechanical strength and glass transition temperature of the material greater than those of the cured product of the bifunctional epoxy precursor - based insulating material. After the glass transition temperature is increased, the breakdown strength of the material also increases. Therefore, due to the special structure of the epoxy precursor, the thermal performance and insulating performance of the insulating material composition are improved synchronously, which broadens its application range and meets the usage requirements of solid insulating materials in the fields of electrical equipment and electronic packaging.

[0009] The present invention also provides a preparation method of the above - mentioned degradable epoxy resin precursor, comprising the following steps:

[0010] (1) Under the action of an acidic catalyst, polyhydroxybenzaldehyde and polyhydric alcohol are subjected to a condensation reaction to prepare an intermediate, and the structure of the intermediate is selected from any one of the following structures:

[0011]

[0012] Wherein, R is the connection position;

[0013] (2) The intermediate obtained in step (1), epichlorohydrin, a phase - transfer catalyst, and sodium hydroxide are mixed and reacted to obtain a degradable epoxy resin precursor.

[0014] In the present invention, using polyhydroxybenzaldehyde as a raw material, first an intermediate containing an acetal group is prepared, and then after an epoxidation reaction, a degradable epoxy resin precursor is obtained. By replacing the types of polyhydroxybenzaldehyde and polyhydric alcohol, different types of acetal - substituted intermediates are obtained. This method is simple, the reaction conditions are controllable, it is easy to implement, and is suitable for large - scale industrial production.

[0015] Preferably, in step (1), the polyhydroxybenzaldehyde is one of 2,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, and 2,3-dihydroxybenzaldehyde.

[0016] Preferably, in step (1), the polyol is one of trimethylolpropane, 2-methyl-1,2,3-propanetriol, and glycerol.

[0017] Preferably, in step (1), the acidic catalyst is at least one of acetic acid, phosphoric acid, sulfuric acid, nitric acid, hydrochloric acid, and solid acid.

[0018] In the present invention, the solid acid can be one of strong acid type ion exchange resin, p-toluenesulfonic acid, and dinitrobenzoic acid.

[0019] Preferably, in step (1), the molar ratio of the polyhydroxybenzaldehyde, polyol, and acidic catalyst is 1:1-1.5:0.1-0.5.

[0020] Preferably, in step (1), the condensation reaction conditions are 120-160 °C and 6-24 h.

[0021] Preferably, in step (2), the phase transfer catalyst is at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, tetradecyltrimethylammonium chloride, tetrabutylammonium hydrogensulfate, trioctylmethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium iodide, and benzyltriethylammonium bromide.

[0022] Preferably, in step (2), the molar ratio of the intermediate, epichlorohydrin, phase transfer catalyst, and sodium hydroxide is 1:10-20:0.03-0.06:10-20.

[0023] Preferably, in step (2), the reaction conditions are 80-120 °C and 6-24 h.

[0024] The present invention also provides an insulating material composition, comprising the above-mentioned degradable epoxy resin precursor, curing agent, epoxy diluent, accelerator, and inorganic filler.

[0025] In the insulating material composition of the present invention, an insulating material cured product with excellent thermodynamic properties and electrical properties can be obtained after curing. During the curing process of the trifunctional epoxy resin precursor, the epoxy groups on the side react with the curing agent to form a highly crosslinked network structure of the cured product, and this crosslinked structure endows the cured product with excellent thermal stability and mechanical properties. The acetal structure in the precursor endows the cured product with good degradation properties.

[0026] Preferably, the curing agent is an acid anhydride curing agent.

[0027] The curing agent of the present invention is an acid anhydride curing agent. Compared with amine curing agents, the acid anhydride curing agent has a lower viscosity after being mixed with the epoxy resin precursor, and the cured product has excellent electrical properties and heat resistance. Among them, the acid anhydride curing agent can be methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methylnadic anhydride, pyromellitic anhydride, biphenyl anhydride, phenylmaleic anhydride, trimellitic anhydride, phthalic anhydride, phenylsuccinic anhydride, pyromellitic dianhydride, 1,8-naphthalic anhydride, 1,2-naphthalic anhydride, 2,3-pyrazinedicarboxylic anhydride, 3-hydroxyphthalic anhydride, 2,3-naphthalenedicarboxylic anhydride, 2,3-pyridinedicarboxylic anhydride, etc.

[0028] Preferably, the epoxy diluent is at least one of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, C12-14 fatty glycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether.

[0029] Preferably, the accelerator is at least one of tertiary amines, tertiary amine salts, quaternary ammonium salts, imidazole compounds, organophosphorus compounds, metal acetylacetonates, metal carboxylates, boron trifluoride amine complexes.

[0030] Preferably, the inorganic filler is at least one of talc, wollastonite, microsilica, barium sulfate, aluminum hydroxide, alumina, boron nitride.

[0031] Preferably, the mass ratio of the degradable epoxy resin precursor, curing agent and accelerator is 1:0.6-1.0:0.001-0.006.

[0032] More preferably, the mass ratio of the degradable epoxy resin precursor, curing agent, epoxy diluent, accelerator and inorganic filler is 1:0.6-1.0:0.1-0.2:0.001-0.006:0.3-0.8.

[0033] The present invention also provides a cured insulating material, which is obtained by pre-curing the above-mentioned insulating material composition through stirring and mixing, and then post-curing.

[0034] The cured insulating material in the present invention has both excellent thermodynamic properties and electrical properties. The cured product can be completely degraded within 1-24 h in an acidic solution (0.1-0.5 M H + ) at 50-120 °C, and has excellent degradable characteristics.

[0035] Preferably, the temperature of the pre-curing is 80-100 °C, and the time is 2-4 h.

[0036] Preferably, the post-curing temperature is 120 - 160 °C and the time is 12 - 24 h.

[0037] Preferably, the glass transition temperature of the cured product of the insulating material is 100 - 180 °C, the tensile strength is 70 - 100 MPa, the thermal conductivity coefficient ≥ 0.5, and the electrical strength ≥ 32 kV / mm; the cured product of the insulating material is completely degraded in an acidic solution at 50 - 120 °C, the concentration of the acidic solution is 0.1 - 0.5 M, and the complete degradation time is 1 - 24 h.

[0038] The present invention also provides the application of the above-mentioned cured product of the insulating material in the fields of power equipment and electronic packaging. The cured product of the insulating material prepared by the present invention has excellent thermodynamic properties and degradable characteristics, and its electrical strength ≥ 32 kV / mm. The insulating material formed by curing the trifunctional precursor and the cured product, due to the reaction of the epoxy functional groups on the side chain with the curing agent, has a higher crosslinking density of the three-dimensional network structure, so its glass transition temperature is higher than that of the cured product obtained by curing the difunctional acetal epoxy resin precursor and the curing agent, which expands its application range. Its electrical strength greater than 32 kV / mm enables it to meet the usage requirements of breakdown-resistant insulating materials in the fields of power equipment and electronic packaging.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) Using bio-based polyhydroxybenzaldehyde as a raw material, a trifunctional acetal-type degradable epoxy resin precursor is developed. The acetal structure can be hydrolyzed under acidic conditions, thereby endowing the epoxy resin material with good degradation performance.

[0041] (2) The cured product of the insulating material prepared from the degradable epoxy resin precursor of the present invention has both excellent thermodynamic properties and electrical properties, and the glass transition temperature of the cured product is 120 - 180 °C; the cured product can be completely degraded within 1 - 24 h in an acidic solution (0.1 - 0.5 M H + ) at 50 - 120 °C, has excellent degradable characteristics, and is suitable for the support, insulation and sealing of power equipment, providing a new way for the green and sustainable development of electrical insulation equipment. Description of the Drawings

[0042] Figure 1 It is the infrared spectrum diagram of the degradable epoxy resin precursor 1 obtained in Example 1.

[0043] Figure 2 It is the thermal conductivity coefficient diagram of the cured products 1 - 3 of the insulating materials in Examples 1 - 3.

[0044] Figure 3DMA curve of the cured product 1 of the insulating material obtained in Example 1.

[0045] Figure 4 Weibull distribution diagram of the AC breakdown strength of the cured product 1 of the insulating material obtained in Example 1.

[0046] Figure 5 Degradation effect diagram of the cured product 1 of the insulating material obtained in Example 1. Detailed implementation manners

[0047] The following further describes the present invention in detail in conjunction with embodiments, but the implementation manners of the present invention are not limited to the following embodiments.

[0048] The raw materials used in the present invention are all commercially available.

[0049] The performance test experiments of the embodiments in the present invention are as follows:

[0050] (1) Glass transition temperature: Using a TA Q800 thermomechanical analyzer from the United States, the loss factor of the material is tested in the tensile mode. The sample size is 30 mm × 10 mm × 1 mm, the temperature rising range is from -50 °C to 250 °C, the temperature rising rate is 3 °C / min, and the peak value of the loss factor is the glass transition temperature of the embodiment of this patent;

[0051] (2) Tensile strength: Using a 5567 universal testing machine produced by Instron Corporation of the United States to test the mechanical properties of the material. The tensile spline is dumbbell-shaped, the sample size is 130 mm × 10 mm × 4 mm, the tensile rate is 2 mm / min, and the gauge length is 110 mm;

[0052] (3) Thermal conductivity: Using a NETZSCH LFA467 laser thermal conductivity meter to measure the out-of-plane thermal diffusivity of composites prepared with different types and different filling amounts of fillers. The sample thickness is about 1 mm. The out-of-plane thermal diffusivity test sample is a 10 × 10 mm square piece, and the surface is evenly sprayed with graphite. After obtaining the thermal diffusivity and specific heat capacity, combined with the sample density (ρ, g cm -3 ), the thermal conductivity k of the material can be calculated by the formula k = α × ρ × C p ;

[0053] (4) Electrical strength: The electrical strength test is based on the standard of GB / T1408.1-2016;

[0054] (5) Degradation performance: Prepare 20 mL of degradation solution, put the sample into a sample bottle containing 20 mL of degradation solution, and then put it into a water bath for degradation experiment, take pictures to record the degradation state until the sample is completely degraded.

[0055] Example 1

[0056] (1) In terms of mole parts, place 1 part of 3,4-dihydroxybenzaldehyde, 1.2 parts of trimethylolpropane, and 0.2 part of phosphoric acid in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 140 °C for 12 hours to obtain Intermediate 1;

[0057] (2) In terms of mole parts, mix 1 part of Intermediate 1, 10 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide, and 10 parts of sodium hydroxide, and react at 120 °C for 8 hours to obtain a degradable epoxy resin precursor 1, the structure of which is as follows, and its infrared spectrum is as Figure 1 shown,

[0058]

[0059] (3) Mix the degradable epoxy resin precursor 1, butyl glycidyl ether, methylhexahydrophthalic anhydride, 1,2-dimethylimidazole, and boron nitride obtained in step (2) in a mass ratio of 1:0.1:0.75:0.001:0.3, pour the mixture into a mold at 80 °C for pre-curing for 4 h, and then cure in a vacuum oven at 120 °C for 12 h to obtain a cured product 1 of the insulating material.

[0060] Performance test of the cured product 1 of the insulating material: The glass transition temperature is 180 °C, the tensile strength is 95 MPa, the thermal conductivity is as Figure 2 shown, which is 0.887 (25 °C), and the electrical strength is 36.12 KV / mm ( Figure 4 ). This cured product of the composite insulating material is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 80 °C in 5 h ( Figure 5 ).

[0061] Example 2

[0062] (1) In terms of mole parts, place 1 part of 2,4-dihydroxybenzaldehyde, 1.5 parts of trimethylolpropane, and 0.5 part of phosphoric acid in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 120 °C for 24 hours to obtain Intermediate 2;

[0063] (2) In terms of mole parts, mix 1 part of Intermediate 2, 20 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide, and 20 parts of sodium hydroxide, and react at 80 °C for 24 hours to obtain a degradable epoxy resin precursor 2, the structure of which is as follows:

[0064]

[0065] (3) Mix the degradable epoxy resin precursor 2, 1,4-butanediol diglycidyl ether, methyltetrahydrophthalic anhydride, cetyl dimethyl benzyl ammonium, and alumina obtained in step (2) in a mass ratio of 1:0.1:1.0:0.006:0.8, pour the mixture into a mold at 100 °C, pre-cure for 2 h, and then cure in a vacuum oven at 160 °C for 12 h to obtain the cured product of the insulating material 2.

[0066] Performance test of the cured product of the insulating material 2: The glass transition temperature is 156 °C, the tensile strength is 82 MPa, the thermal conductivity is as Figure 2 shown, which is 1.03 (25 °C), and the electrical strength is 32.6 KV / mm. This composite insulating material cured product completely degrades in a 0.3 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 80 °C in 10 h.

[0067] Example 3

[0068] (1) In terms of molar parts, place 1 part of 1,2-dihydroxybenzaldehyde, 1 part of trimethylolpropane, and 0.1 part of phosphoric acid in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 120 °C for 24 hours to obtain intermediate 3;

[0069] (2) In terms of molar parts, mix 1 part of intermediate 3, 10 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide, and 10 parts of sodium hydroxide, and react at 110 °C for 12 hours to obtain the degradable epoxy resin precursor 3, the structure of which is as follows:

[0070]

[0071] (3) Mix the degradable epoxy resin precursor 3, ethylene glycol diglycidyl ether, methyl nadic anhydride, 1,2-dimethylimidazole, and wollastonite obtained in step (2) in a mass ratio of 1:0.2:0.75:0.001:0.8, pour the mixture into a mold at 100 °C, pre-cure for 2 h, and then cure in a vacuum oven at 130 °C for 24 h to obtain the cured product of the insulating material 3.

[0072] Performance test of the cured product of the insulating material 3: The glass transition temperature is 145 °C, the tensile strength is 95 MPa, the thermal conductivity is as Figure 2 shown, which is 0.53 (25 °C), and the electrical strength is 33.4 KV / mm. This composite insulating material cured product completely degrades in a 0.1 mol / L hydrochloric acid tetrahydrofuran-water (1:1) solution at 60 °C in 20 h.

[0073] Example 4

[0074] (1) Take 1 part of 3,4-dihydroxybenzaldehyde, 1 part of 2-methyl-1,2,3-propanetriol and 0.1 part of p-toluenesulfonic acid in parts by mole, place them in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 160 °C for 6 hours to obtain intermediate 4;

[0075] (2) Take 1 part of intermediate 4, 15 parts of epichlorohydrin, 0.06 part of tetrabutylammonium bromide and 15 parts of sodium hydroxide in parts by mole, mix them, and react at 100 °C for 18 hours to obtain a degradable epoxy resin precursor 4, the structure of which is as follows:

[0076]

[0077] (3) Mix the degradable epoxy resin precursor 4, polypropylene glycol diglycidyl ether, methyltetrahydrophthalic anhydride, N,N-dimethylbenzylamine and microsilica powder obtained in step (2) according to a mass ratio of 1:0.1:0.6:0.002:0.75, pour them into a mold at 100 °C for pre-curing for 2 h, and then cure in a vacuum oven at 130 °C for 20 h to obtain an insulating material cured product 4.

[0078] Performance test of the insulating material cured product 4: The glass transition temperature is 130 °C, the tensile strength is 82 MPa, the thermal conductivity is 0.53 (25 °C), and the electrical strength is 33.2 KV / mm. This composite insulating material cured product is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (1:1) solution at 50 °C in 12 h.

[0079] Example 5

[0080] (1) Take 1 part of 2,4-dihydroxybenzaldehyde, 1 part of 2-methyl-1,2,3-propanetriol and 0.2 part of p-toluenesulfonic acid in parts by mole, place them in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 120 °C for 24 hours to obtain intermediate 5;

[0081] (2) Take 1 part of intermediate 5, 15 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide and 15 parts of sodium hydroxide in parts by mole, mix them, and react at 100 °C for 20 hours to obtain a degradable epoxy resin precursor 5, the structure of which is as follows:

[0082]

[0083] (3) Mix the degradable epoxy resin precursor 5, butyl glycidyl ether, methyl nadic anhydride, N,N-dimethylbenzylamine and microsilica powder obtained in step (2) according to a mass ratio of 1:0.1:1.0:0.001:0.8, pour them into a mold at 80 °C for pre-curing for 4 h, and then cure in a vacuum oven at 120 °C for 24 h to obtain an insulating material cured product 5.

[0084] Performance test of the cured product 5 of the insulating material: The glass transition temperature is 120 °C, the tensile strength is 75 MPa, the thermal conductivity is 0.545 (25 °C), and the electrical strength is 32.15 KV / mm. The cured product of this composite insulating material is completely degraded in a 0.1 mol / L hydrochloric acid tetrahydrofuran-water (1:1) solution at 50 °C for 24 h.

[0085] Example 6

[0086] (1) In terms of molar parts, 1 part of 2,3-dihydroxybenzaldehyde, 1 part of 2-methyl-1,2,3-propanetriol, and 0.2 part of p-toluenesulfonic acid are placed in a three-necked flask equipped with mechanical stirring and nitrogen purging, and reacted at 140 °C for 6 hours to obtain intermediate 6;

[0087] (2) In terms of molar parts, 1 part of intermediate 6, 10 parts of epichlorohydrin, 0.06 part of tetrabutylammonium bromide, and 10 parts of sodium hydroxide are mixed and reacted at 120 °C for 6 hours to obtain a degradable epoxy resin precursor 6, and the structure is as follows:

[0088]

[0089] (3) The degradable epoxy resin precursor 6, 1,6-hexanediol diglycidyl ether, phthalic anhydride, N,N-dimethylbenzylamine, and alumina obtained in step (2) are mixed according to a mass ratio of 1:0.1:0.75:0.001:0.7, poured into a mold at 100 °C for pre-curing for 4 h, and then cured in a vacuum oven at 160 °C for 12 h to obtain the cured product 6 of the insulating material.

[0090] Performance test of the cured product 6 of the insulating material: The glass transition temperature is 135 °C, the tensile strength is 71 MPa, the thermal conductivity is 0.986 (25 °C), and the electrical strength is 35.6 KV / mm. The cured product of this composite insulating material is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 120 °C for 1 h.

[0091] Example 7

[0092] (1) In terms of molar parts, 1 part of 2,4-dihydroxybenzaldehyde, 1 part of glycerol, and 0.5 part of nitric acid are placed in a three-necked flask equipped with mechanical stirring and nitrogen purging, and reacted at 150 °C for 8 hours to obtain intermediate 7;

[0093] (2) In terms of molar parts, 1 part of intermediate 7, 12 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide, and 12 parts of sodium hydroxide are mixed and reacted at 120 °C for 6 hours to obtain a degradable epoxy resin precursor 7, and the structure is as follows:

[0094]

[0095] (3) Mix the degradable epoxy resin precursor 7, butyl glycidyl ether, trimellitic anhydride, N,N-dimethylbenzylamine, and aluminum nitride obtained in step (2) in a mass ratio of 1:0.1:0.75:0.001:0.6, pour the mixture into a mold at 100 °C, and pre-cure for 4 h, then cure in a vacuum oven at 150 °C for 20 h to obtain the cured product 7 of the insulating material.

[0096] Performance test of the cured product 7 of the insulating material: The glass transition temperature is 125 °C, the tensile strength is 88 MPa, the thermal conductivity is 0.61 (25 °C), and the electrical strength is 33.25 KV / mm. The cured product of this composite insulating material is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (1:1) solution at 50 °C in 12 h.

[0097] Example 8

[0098] (1) In terms of mole parts, place 1 part of 3,4-dihydroxybenzaldehyde, 1.5 parts of glycerol, and 0.1 part of strong acid type ion exchange resin in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 150 °C for 8 hours to obtain intermediate 8;

[0099] (2) In terms of mole parts, mix 1 part of intermediate 8, 12 parts of epichlorohydrin, 0.06 part of tetrabutylammonium bromide, and 12 parts of sodium hydroxide, and react at 80 °C for 24 hours to obtain the degradable epoxy resin precursor 8, the structure of which is shown as follows:

[0100]

[0101] (3) Mix the degradable epoxy resin precursor 8, butyl glycidyl ether, methylhexahydrophthalic anhydride, 2-methylimidazole, and talc powder obtained in step (2) in a mass ratio of 1:0.1:0.75:0.001:0.8, pour the mixture into a mold at 90 °C, and pre-cure for 3 h, then cure in a vacuum oven at 160 °C for 12 h to obtain the cured product 8 of the insulating material.

[0102] Performance test of the cured product 8 of the insulating material: The glass transition temperature is 120 °C, the tensile strength is 80 MPa, the thermal conductivity is 0.58 (25 °C), and the electrical strength is 35.78 KV / mm. The cured product of this composite insulating material is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 80 °C in 4 h.

[0103] Example 9

[0104] (1) In terms of mole parts, place 1 part of 2,3-dihydroxybenzaldehyde, 1 part of glycerol, and 0.5 part of phosphoric acid in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 140 °C for 12 hours to obtain intermediate 9;

[0105] (2) Mix 1 part of intermediate 9, 20 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide, and 20 parts of sodium hydroxide in terms of mole fraction, and react at 100 °C for 6 hours to obtain a degradable epoxy resin precursor 9 with the structure shown below:

[0106]

[0107] (3) Mix the degradable epoxy resin precursor 9 obtained in step (2), butyl glycidyl ether, pyromellitic dianhydride, 2-methylimidazole, and microsilica in a mass ratio of 1:0.1:1.0:0.001:0.7, pour the mixture into a mold at 90 °C for pre-curing for 4 h, and then cure in a vacuum oven at 130 °C for 24 h to obtain a cured product 9 of the insulating material.

[0108] Performance test of the cured product 9 of the insulating material: The glass transition temperature is 155 °C, the tensile strength is 100 MPa, the thermal conductivity is 0.57 (25 °C), and the electrical strength is 32.9 KV / mm. This cured product of the composite insulating material is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 120 °C in 1 h.

[0109] Example 10

[0110] (1) Place 1 part of 2,4-dihydroxybenzaldehyde, 1 part of glycerol, and 0.4 part of acetic acid in a three-necked flask equipped with mechanical stirring and nitrogen purging, and react at 150 °C for 10 hours to obtain intermediate 10;

[0111] (2) Mix 1 part of intermediate 10, 20 parts of epichlorohydrin, 0.06 part of tetrabutylammonium bromide, and 20 parts of sodium hydroxide in terms of mole fraction, and react at 100 °C for 18 hours to obtain a degradable epoxy resin precursor 10 with the structure shown below:

[0112]

[0113] (3) Mix the degradable epoxy resin precursor 10 obtained in step (2), butyl glycidyl ether, trimellitic anhydride, N,N-dimethylbenzylamine, and aluminum nitride in a mass ratio of 1:0.15:0.6:0.006:0.65, pour the mixture into a mold at 100 °C for pre-curing for 2 h, and then cure in a vacuum oven at 120 °C for 24 h to obtain a cured product 10 of the insulating material.

[0114] Performance test of the cured product 10 of the insulating material: The glass transition temperature is 100 °C, the tensile strength is 70 MPa, the thermal conductivity is 0.61 (25 °C), and the electrical strength is 32.25 KV / mm. This cured product of the composite insulating material is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (1:1) solution at 50 °C in 12 h.

[0115] Example 11

[0116] (1) Taking parts by mole, 1 part of 3,4-dihydroxybenzaldehyde, 1 part of glycerol and 0.5 part of strong acid type ion exchange resin are placed in a three-necked flask equipped with mechanical stirring and nitrogen purging, and reacted at 150 °C for 8 hours to obtain Intermediate 11;

[0117] (2) Taking parts by mole, 1 part of Intermediate 11, 12 parts of epichlorohydrin, 0.03 part of tetrabutylammonium bromide and 12 parts of sodium hydroxide are mixed, and reacted at 100 °C for 16 hours to obtain a degradable epoxy resin precursor 11, the structure of which is as follows:

[0118]

[0119] (3) The degradable epoxy resin precursor 11 obtained in step (2), butyl glycidyl ether, methyl hexahydrophthalic anhydride, 2-methylimidazole and talcum powder are mixed in a mass ratio of 1:0.2:0.75:0.001:0.8 and then poured into a mold at 90 °C for pre-curing for 2 h, and then cured in a vacuum oven at 140 °C for 15 h to obtain a cured product of insulating material 11.

[0120] Performance test of the cured product of insulating material 11: The glass transition temperature is 125 °C, the tensile strength is 80 MPa, the thermal conductivity is 0.58 (25 °C), and the electrical strength is 32.5 KV / mm. This composite insulating material cured product is completely degraded in a 0.5 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 80 °C for 8 h.

[0121] Example 12

[0122] (1) Taking parts by mole, 1 part of 2,3-dihydroxybenzaldehyde, 1 part of glycerol and 0.4 part of phosphoric acid are placed in a three-necked flask equipped with mechanical stirring and nitrogen purging, and reacted at 140 °C for 12 hours to obtain Intermediate 12;

[0123] (2) Taking parts by mole, 1 part of Intermediate 12, 20 parts of epichlorohydrin, 0.05 part of tetrabutylammonium bromide and 20 parts of sodium hydroxide are mixed, and reacted at 80 °C for 24 hours to obtain a degradable epoxy resin precursor 12, the structure of which is as follows:

[0124]

[0125] (3) Mix the degradable epoxy resin precursor 12, butyl glycidyl ether, pyromellitic dianhydride, 2-methylimidazole, and microsilica powder obtained in step (2) in a mass ratio of 1:0.2:0.6:0.005:0.65, pour the mixture into a mold at 80 °C for pre-curing for 2 h, and then cure it in a vacuum oven at 160 °C for 24 h to obtain the cured product 9 of the insulating material.

[0126] Performance test of the cured product 12 of the insulating material: The glass transition temperature is 165 °C, the tensile strength is 85 MPa, the thermal conductivity is 0.50 (25 °C), and the electrical strength is 32.9 KV / mm. The cured product of this composite insulating material is completely degraded in a 0.1 mol / L hydrochloric acid tetrahydrofuran-water (9:1) solution at 50 °C in 24 h.

[0127] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A degradable epoxy resin precursor, characterized in that, The structure of the epoxy resin precursor is shown in any one of formulas (I) to (III): wherein, R is a connection position.

2. The preparation method of the degradable epoxy resin precursor according to claim 1, wherein, It includes the following steps: (1) Under the action of an acidic catalyst, polyhydroxybenzaldehyde and polyol are subjected to a condensation reaction to prepare an intermediate, and the structure of the intermediate is selected from any one of the following structures: wherein, R is a connection position; (2) The intermediate obtained in step (1), epichlorohydrin, a phase transfer catalyst, and sodium hydroxide are mixed and reacted to obtain a degradable epoxy resin precursor.

3. The preparation method of the degradable epoxy resin precursor according to claim 2, wherein, In step (1), the polyhydroxybenzaldehyde is one of 2,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzaldehyde, and 2,3-dihydroxybenzaldehyde; The polyol is one of trimethylolpropane, 2-methyl-1,2,3-propanetriol, and glycerol; The acidic catalyst is at least one of acetic acid, phosphoric acid, sulfuric acid, nitric acid, hydrochloric acid, and solid acid; The molar ratio of the polyhydroxybenzaldehyde, polyol, and acidic catalyst is 1:1 to 1.5:0.1 to 0.

5.

4. The preparation method of the degradable epoxy resin precursor according to claim 2, wherein, In step (2), the phase transfer catalyst is at least one of tetrabutylammonium bromide, benzyltriethylammonium chloride, tetradecyltrimethylammonium chloride, tetrabutylammonium hydrogensulfate, trioctylmethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium iodide, and benzyltriethylammonium bromide; the molar ratio of the intermediate, epichlorohydrin, phase transfer catalyst, and sodium hydroxide is 1:10 to 20:0.03 to 0.06:10 to 20.

5. An insulating material composition, characterized in that, It includes the degradable epoxy resin precursor, curing agent, epoxy diluent, accelerator, and inorganic filler described in claim 1.

6. The insulating material composition according to claim 5, characterized in that, The curing agent is an acid anhydride curing agent; The epoxy diluent is at least one of butyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether, C12-14 fatty glycidyl ether, 1,4-butanediol diglycidyl ether, ethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; The accelerator is at least one of tertiary amines, tertiary amine salts, quaternary ammonium salts, imidazole compounds, organophosphorus compounds, metal acetylacetonates, metal carboxylates, and boron trifluoride amine complexes; The inorganic filler is at least one of talc, wollastonite, microsilica, barium sulfate, aluminum hydroxide, alumina, and boron nitride.

7. The insulating material composition according to claim 5, characterized in that, The mass ratio of the degradable epoxy resin precursor, curing agent, and accelerator is 1:0.6 to 1.0:0.001 to 0.

006.

8. A cured product of an insulating material, characterized in that, The cured product is obtained by stirring and mixing the insulating material composition described in any one of claims 5 to 7 for pre-curing at a temperature of 80 to 100 °C for 2 to 4 h, and then post-curing at a temperature of 120 to 160 °C for 12 to 24 h.

9. The cured product of the insulating material according to claim 8, wherein The glass transition temperature of the cured insulating material is 120 to 180 °C, the tensile strength is 70 to 100 MPa, the thermal conductivity is ≥0.5, and the electrical strength is ≥32 KV / mm; the cured insulating material is completely degraded in an acidic solution at 50 to 120 °C, the concentration of the acidic solution is 0.1 to 0.5 M, and the complete degradation time is 1 to 24 h.

10. Use of the cured insulating material according to claim 8 or 9 in the fields of electrical equipment and electronic packaging.

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