Preparation process of toughened modified epoxy resin

Abstract

The invention relates to the technical field of epoxy resin, and discloses a preparation process of toughened modified epoxy resin, tetravinyl cyclotetrasiloxane reacts under epoxidation of m-chloroperoxybenzoic acid to obtain tetraepoxy cyclotetrasiloxane, the tetraepoxy cyclotetrasiloxane and amino in naphthylamine are subjected to ring-opening reaction to obtain tetra (hydroxy naphthylamine) cyclotetrasiloxane, and the tetra (hydroxy naphthylamine) cyclotetrasiloxane is subjected to ring-opening reaction to obtain the toughened modified epoxy resin. Carrying out cross-linking polymerization reaction on four hydroxyl groups contained in the hyperbranched polymer and isophorone diisocyanate to obtain a hyperbranched polymer containing naphthalene rings and organic silicon; and adding the hyperbranched polymer containing the naphthalene ring and the organic silicon into the epoxy resin for curing to obtain the toughened modified epoxy resin. When the hyperbranched polymer prepared by the method is applied to epoxy resin, the mechanical properties such as thermal stability and toughness of an epoxy resin material can be effectively improved.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resins, in particular to a preparation process of a toughened modified epoxy resin. Background Art

[0002] Epoxy resin is a high molecular polymer with two or more epoxy groups. It has excellent adhesive properties, electrical insulation and chemical stability and is widely used in machinery, electronics, chemical industry and other fields. However, epoxy resin has poor impact resistance and toughness, and its application range is limited. Therefore, how to improve its toughness and impact resistance in order to expand its application range has become one of the current research hotspots. Hyperbranched polymers have the characteristics of low viscosity, high functionality and good solubility. They are widely used in various fields and have become a method of toughening epoxy resin.

[0003] In the prior art, the toughening methods of epoxy resin mainly include toughening with core-shell polymer, IPN, thermotropic liquid crystal polymer, rubber elastomer, nanoparticle, etc. However, these toughening methods, while improving the toughness of the resin, will cause a significant decrease in the tensile strength and bending strength of the resin; Patent application number CN112920678B discloses a method for preparing a hyperbranched polymer grafted graphene modified epoxy resin coating, and a pyridine-based hyperbranched polymer grafted graphene is prepared, which is blended with epoxy resin to prepare a coating having excellent mechanical properties and anti-corrosion properties, but poor thermal stability.

[0004] Organic silicon refers to a compound containing a silicon-carbon bond and at least one organic group directly connected to a silicon atom. The siloxane structure has low surface tension, high and low temperature resistance, oxidation resistance, and corrosion resistance, and is widely used in the fields of electronics, construction, chemicals, and textiles. Naphthalene is a simple condensed aromatic hydrocarbon, which is widely used in the fields of dyes, resins, and solvents. For example, the patent application number CN109651596B reports an epoxy resin containing a naphthalene ring structure and a preparation method thereof. The prepared epoxy resin has excellent heat resistance, but its mechanical properties are poor. Summary of the invention

[0005] The technical problem solved by the present invention is: to provide a preparation process of a toughened modified epoxy resin, wherein a new type of hyperbranched polymer with excellent mechanical and thermal stability is prepared, and the polymer is applied to the epoxy resin to solve the problem of poor mechanical and thermal stability of the epoxy resin.

[0006] The technical solution of the present invention is: A preparation process of a toughened modified epoxy resin, the preparation process comprising: (1) Dissolve isophorone diisocyanate in N,N-dimethylformamide solution, add tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and dibutyltin dilaurate catalyst thereto under nitrogen environment, raise the temperature to 55-70°C, react for 2-5h, and after the reaction is completed, obtain a hyperbranched polymer containing naphthalene rings and organosilicon.

[0007] (2) Add the hyperbranched polymer containing naphthalene rings and silicone to the epoxy resin, stir evenly, add a curing agent and a defoaming agent, stir for 15-30 minutes, vacuum degas, pour into a mold, and cure to obtain a toughened modified epoxy resin.

[0008] Furthermore, in step (1), the molar ratio of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane, isophorone diisocyanate, and dibutyltin dilaurate is 1:2-2.5:0.08-0.15.

[0009] Furthermore, in step (2), the mass of the hyperbranched polymer containing naphthalene rings and organosilicon is 1-10% of the mass of the epoxy resin.

[0010] Furthermore, in step (2), the stirring temperature is 35-45° C., and the stirring time is 50-80 min.

[0011] Furthermore, in step (2), the curing process is curing at 80°C for 4 hours, curing at 120°C for 2 hours, curing at 150°C for 4 hours, and curing at 180°C for 2 hours.

[0012] Furthermore, the preparation process of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane in step (1) is as follows: (3) Dissolve m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Add dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at -5 to 0°C for 8 to 15 hours. After the reaction is completed, tetraepoxycyclotetrasiloxane is obtained.

[0013] (4) Under nitrogen protection, naphthylamine, tetraepoxycyclotetrasiloxane and tetrahydrofuran solvent are placed in a flask and reacted at 25-40°C for 4-10 hours to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane; the preparation route is as follows:

[0014] Furthermore, in step (3), the molar concentration of tetravinylcyclotetrasiloxane and m-chloroperoxybenzoic acid is 1:4.5-5.

[0015] Furthermore, in the step (4), the molar ratio of tetraepoxycyclotetrasiloxane to naphthylamine is 1:4-5.

[0016] The beneficial technical effects of the present invention are: Tetravinylcyclotetrasiloxane is epoxidized by m-chloroperoxybenzoic acid to obtain tetraepoxycyclotetrasiloxane, which is then subjected to a ring-opening reaction with the amino group in naphthylamine to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane, and the four hydroxyl groups contained in the tetrakis(hydroxynaphthylamine)cyclotetrasiloxane undergo a cross-linking polymerization reaction with isophorone diisocyanate to obtain a hyperbranched polymer containing naphthalene rings and silicone; the hyperbranched polymer containing naphthalene rings and silicone is then added to an epoxy resin for curing to obtain a toughened modified epoxy resin.

[0017] The hyperbranched polymer containing naphthalene rings and organosilicon prepared by the present invention has a naphthalene ring in a plane rigid structure with highly conjugated double bonds, and molecules are closely arranged and stacked with each other, so that the crosslinking density is increased and the thermal stability is enhanced. In addition, the hyperbranched polymer also has a siloxane structure, and can form a glass layer on the surface when heated to block heat transfer and energy transfer, and the two assist each other to jointly improve the thermal stability of the material. In addition, the hyperbranched polymer itself has a huge network structure and a cavity structure, and has good compatibility with epoxy resin. When the hyperbranched polymer is added into the epoxy resin, the epoxy resin is used as a continuous phase, and the hyperbranched polymer is used as a dispersed phase and is dispersed in the matrix of the epoxy resin. When impacted, the self-yield deformation of the dispersed phase of the hyperbranched polymer can effectively absorb external energy. In addition, the hyperbranched polymer can also serve as a stress concentrator to further prevent the generation of cracks. The bond energy of the silicon-oxygen bond in the siloxane structure is larger than that of the carbon-carbon bond, and the impact energy can also be absorbed when impacted. The two act synergistically to improve the mechanical properties of the material such as toughness. The hyperbranched polymer prepared by the present invention is applied to epoxy resin, and can effectively improve mechanical properties such as thermal stability and toughness of the epoxy resin material. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a test chart of the mechanical properties of epoxy resin.

[0019] Figure 2 This is a test chart of thermal decomposition temperature of epoxy resin. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. 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.

[0021] The present invention is further described below in conjunction with specific embodiments and drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. Example 1

[0022] (1) Dissolve 0.045 mol of m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Then add 0.01 mol of dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at -5°C for 10 hours. After the reaction is completed, extract and wash with sodium sulfite and deionized water in sequence. The organic phase is rotary evaporated, washed with petroleum ether and dried to obtain tetraepoxycyclotetrasiloxane.

[0023] (2) Under nitrogen protection, 0.75 mol of naphthylamine, 0.015 mol of tetracyclylcyclotetrasiloxane and tetrahydrofuran solvent were placed in a flask, reacted at 30°C for 8 h, rotary evaporated, washed with petroleum ether and dried to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

[0024] (3) Dissolve 0.2 mol of isophorone diisocyanate in N,N-dimethylformamide solution, add 0.1 mol of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and 0.01 mol of dibutyltin dilaurate catalyst thereto under nitrogen environment, raise the temperature to 70°C, react for 4 hours, and after the reaction is completed, centrifuge, wash with ethanol, and dry to obtain a hyperbranched polymer containing naphthalene rings and silicone.

[0025] (4) Add 5 g of a hyperbranched polymer containing naphthalene rings and silicone to 500 g of an epoxy resin, stir at 40°C for 60 min, add 4 g of a DF-6500 defoamer and a diethyltoluenediamine curing agent, wherein the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin is 0.8, stir for 20 min, degas in a vacuum, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain a toughened modified epoxy resin. Example 2

[0026] (1) Dissolve 0.05 mol of m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Then add 0.01 mol of dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at 0°C for 12 hours. After the reaction is completed, extract and wash with sodium sulfite and deionized water in sequence. The organic phase is rotary evaporated, washed with petroleum ether and dried to obtain tetraepoxycyclotetrasiloxane.

[0027] (2) Under nitrogen protection, 0.07 mol of naphthylamine, 0.015 mol of tetracyclylcyclotetrasiloxane and tetrahydrofuran solvent were placed in a flask, reacted at 40°C for 5 h, rotary evaporated, washed with petroleum ether and dried to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

[0028] (3) Dissolve 0.2 mol of isophorone diisocyanate in N,N-dimethylformamide solution, add 0.1 mol of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and 0.008 mol of dibutyltin dilaurate catalyst thereto under nitrogen environment, raise the temperature to 70°C, react for 4 hours, and after the reaction is completed, centrifuge, wash with ethanol, and dry to obtain a hyperbranched polymer containing naphthalene rings and silicone.

[0029] (4) Add 16 g of a hyperbranched polymer containing naphthalene rings and silicone to 500 g of an epoxy resin, stir at 35°C for 80 min, add 4 g of a DF-6500 defoamer and a diethyltoluenediamine curing agent, wherein the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin is 0.8, stir for 20 min, degas in a vacuum, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain a toughened modified epoxy resin. Example 3

[0030] (1) Dissolve 0.048 mol of m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Then add 0.01 mol of dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at -3°C for 10 hours. After the reaction is completed, extract and wash with sodium sulfite and deionized water in sequence. The organic phase is rotary evaporated, washed with petroleum ether and dried to obtain tetraepoxycyclotetrasiloxane.

[0031] (2) Under nitrogen protection, 0.065 mol of naphthylamine, 0.015 mol of tetracyclylcyclotetrasiloxane and tetrahydrofuran solvent were placed in a flask, reacted at 30°C for 8 h, and then rotary evaporated, washed with petroleum ether and dried to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

[0032] (3) 0.24 mol of isophorone diisocyanate was dissolved in N,N-dimethylformamide solution, and 0.1 mol of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and 0.015 mol of dibutyltin dilaurate catalyst were added thereto under nitrogen environment. The temperature was raised to 60°C and the reaction was carried out for 4 hours. After the reaction was completed, the mixture was centrifuged, washed with ethanol, and dried to obtain a hyperbranched polymer containing naphthalene rings and silicone.

[0033] (4) Add 27 g of a hyperbranched polymer containing naphthalene rings and silicone to 500 g of an epoxy resin, stir at 40°C for 50 min, add 4 g of a DF-6500 defoamer and a diethyltoluenediamine curing agent, wherein the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin is 0.8, stir for 15 min, degas in a vacuum, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain a toughened modified epoxy resin. Example 4

[0034] (1) Dissolve 0.05 mol of m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Then add 0.01 mol of dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at -5°C for 15 hours. After the reaction is completed, extract and wash with sodium sulfite and deionized water in sequence. The organic phase is rotary evaporated, washed with petroleum ether and dried to obtain tetraepoxycyclotetrasiloxane.

[0035] (2) Under nitrogen protection, 0.075 mol of naphthylamine, 0.015 mol of tetracyclylcyclotetrasiloxane and tetrahydrofuran solvent were placed in a flask, reacted at 40°C for 4 h, rotary evaporated, washed with petroleum ether and dried to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

[0036] (3) Dissolve 0.25 mol of isophorone diisocyanate in N,N-dimethylformamide solution, add 0.1 mol of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and 0.012 mol of dibutyltin dilaurate catalyst thereto under nitrogen environment, raise the temperature to 60°C, react for 5 hours, and after the reaction is completed, centrifuge, wash with ethanol, and dry to obtain a hyperbranched polymer containing naphthalene rings and silicone.

[0037] (4) Add 38 g of a hyperbranched polymer containing naphthalene rings and silicone to 500 g of an epoxy resin, stir at 45°C for 50 min, add 4 g of a DF-6500 defoamer and a diethyltoluenediamine curing agent, wherein the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin is 0.8, stir for 20 min, degas in a vacuum, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain a toughened modified epoxy resin. Example 5

[0038] (1) Dissolve 0.049 mol of m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Then add 0.01 mol of dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at -5°C for 15 hours. After the reaction is completed, extract and wash with sodium sulfite and deionized water in sequence. The organic phase is rotary evaporated, washed with petroleum ether and dried to obtain tetraepoxycyclotetrasiloxane.

[0039] (2) Under nitrogen protection, 0.06 mol of naphthylamine, 0.015 mol of tetracyclylcyclotetrasiloxane and tetrahydrofuran solvent were placed in a flask, reacted at 25°C for 8 h, rotary evaporated, washed with petroleum ether and dried to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

[0040] (3) Dissolve 0.25 mol of isophorone diisocyanate in N,N-dimethylformamide solution, add 0.1 mol of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and 0.008 mol of dibutyltin dilaurate catalyst thereto under nitrogen environment, raise the temperature to 70°C, react for 2 h, and after the reaction is completed, centrifuge, wash with ethanol, and dry to obtain a hyperbranched polymer containing naphthalene rings and silicone.

[0041] (4) Add 50 g of a hyperbranched polymer containing naphthalene rings and silicone to 500 g of an epoxy resin, stir at 45°C for 50 min, add 4 g of a DF-6500 defoamer and a diethyltoluenediamine curing agent, wherein the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin is 0.8, stir for 20 min, degas in a vacuum, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain a toughened modified epoxy resin.

[0042] Comparative Example 1 (1) Dissolve 0.045 mol of m-chloroperoxybenzoic acid in dichloromethane and stir to dissolve. Then add 0.01 mol of dichloromethane solution of tetravinylcyclotetrasiloxane and stir to react at -5°C for 10 hours. After the reaction is completed, extract and wash with sodium sulfite and deionized water in sequence. The organic phase is rotary evaporated, washed with petroleum ether and dried to obtain tetraepoxycyclotetrasiloxane.

[0043] (2) Under nitrogen protection, 0.075 mol of naphthylamine, 0.015 mol of tetracyclylcyclotetrasiloxane and tetrahydrofuran solvent were placed in a flask, reacted at 30°C for 8 h, and then rotary evaporated, washed with petroleum ether, and dried to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

[0044] (3) Add 5 g of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane to 500 g of epoxy resin, stir at 40°C for 60 min, add 4 g of DF-6500 defoamer and diethyltoluenediamine curing agent, the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin is 0.8, stir for 20 min, vacuum degass, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain an epoxy resin material.

[0045] Comparative Example 2 (4) Add 4 g of DF-6500 defoamer and diethyltoluenediamine curing agent to the epoxy resin, with the ratio of the active hydrogen equivalent of the curing agent to the epoxy equivalent of the epoxy resin being 0.8. Stir for 20 min, degas in vacuum, pour into a mold, and cure at 80°C for 4 h, 120°C for 2 h, 150°C for 4 h, and 180°C for 2 h to obtain an epoxy resin material.

[0046] A simply supported beam pendulum impact testing machine is used to test the impact properties of the material.

[0047] An electronic universal testing machine is used to test the bending properties of the material.

[0048] Attached to the instruction manual Figure 1 It can be seen that in the examples, the impact strength of the epoxy resin material of Example 3 is relatively large, which is 35.9 kJ / m 2 The impact strength of the epoxy resin material in Example 5 is relatively small, which is 20.6 kJ / m 2 The impact performance of the epoxy resin material in Comparative Example 2 is the smallest, which is 9.1 kJ / m 2 , the bending strength of the epoxy resin material of Example 4 is relatively large, which is 139.6MPa, the bending strength of the epoxy resin material of Example 1 is relatively small, which is 112.3MPa, and the bending strength of the epoxy resin material of Comparative Example 2 is the smallest, which is only 88.1MPa. This is because in Examples 1-5, hyperbranched polymers containing naphthalene rings and organosilicon are added, wherein the silicon oxygen bond energy is larger than the silicon carbon bond energy, and more energy can be absorbed when impacted, and due to the larger network structure and cavity structure of the hyperbranched polymer, it has a larger cross-linking density, and the hyperbranched polymer is dispersed in the epoxy resin as a dispersion, and when impacted, it can also absorb larger energy, and enhance the mechanical properties such as toughness of the epoxy resin. In Comparative Example 1, only tetrakis (hydroxynaphthylamine) cyclotetrasiloxane is added, which has a certain impact strength, while in Comparative Example 2, no toughening material is added, so its mechanical properties are the worst.

[0049] The T of epoxy resin material samples was tested by DSC. g , the heating rate is 10℃ / min, and the temperature range is 50-400℃.

[0050] The material was subjected to thermogravimetric analysis using a comprehensive thermal analyzer, with a heating rate of 10°C / min and a temperature range of 30-550°C. g is the glass transition temperature. i is the initial weight loss temperature; T 50% It is the temperature at which the thermal decomposition rate reaches the highest level.

[0051] Attached to the instruction manual Figure 2It can be seen that the T of the epoxy resin material of Example 3 g , T i The maximum values ​​are 197°C and 338°C respectively. The T 50% The maximum is 438°C, which is larger than that of Comparative Examples 1 and 2. This is because Examples 1-5 have a naphthalene ring structure and an organosilicon structure with strong thermal stability. The naphthalene ring is a rigid planar structure, which is stacked and arranged with each other, has a large cross-linking density and strong thermal stability. The organosilicon structure generates a glassy layer when heated to block heat transfer and material transfer. The two assist each other to improve the thermal stability of the epoxy resin material. Comparative Example 1 only adds an organosilicon structure, and its thermal stability effect is not as good as that of Examples 1-5. Comparative Example 2 does not add any substance, so its thermal stability is the worst.

[0052] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A process for preparing a toughened modified epoxy resin, characterized in that: The preparation process is: (1) dissolving isophorone diisocyanate in N,N-dimethylformamide solution, adding tetrakis(hydroxynaphthylamine)cyclotetrasiloxane and dibutyltin dilaurate catalyst thereto under nitrogen environment, raising the temperature to 55-70° C., reacting for 2-5 hours, and obtaining a hyperbranched polymer containing naphthalene rings and organosilicon after the reaction is completed; (2) adding a hyperbranched polymer containing naphthalene rings and organosilicon to an epoxy resin, stirring evenly, adding a curing agent and a defoaming agent thereto, stirring for 15-30 minutes, vacuum degassing, pouring into a mold, and curing to obtain a toughened modified epoxy resin; The preparation process of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane in step (1) is as follows: (3) dissolving m-chloroperoxybenzoic acid in dichloromethane, stirring to dissolve, adding dichloromethane solution of tetravinylcyclotetrasiloxane thereto, stirring and reacting at -5 to 0°C for 8 to 15 hours, and obtaining tetraepoxycyclotetrasiloxane after the reaction is completed; (4) Under nitrogen protection, naphthylamine, tetraepoxycyclotetrasiloxane and tetrahydrofuran solvent are placed in a flask and reacted at 25-40°C for 4-10 hours to obtain tetrakis(hydroxynaphthylamine)cyclotetrasiloxane.

2. The process for preparing the toughened modified epoxy resin according to claim 1, characterized in that: In the step (1), the molar ratio of tetrakis(hydroxynaphthylamine)cyclotetrasiloxane, isophorone diisocyanate and dibutyltin dilaurate is 1:2-2.5:0.08-0.

15.

3. The process for preparing the toughened modified epoxy resin according to claim 1, characterized in that: In the step (2), the mass of the hyperbranched polymer containing naphthalene rings and organosilicon is 1-10% of the mass of the epoxy resin.

4. The process for preparing the toughened modified epoxy resin according to claim 1, characterized in that: The stirring temperature in step (2) is 35-45° C. and the stirring time is 50-80 min.

5. The process for preparing the toughened modified epoxy resin according to claim 1, characterized in that: The curing process in step (2) is curing at 80°C for 4 hours, curing at 120°C for 2 hours, curing at 150°C for 4 hours, and curing at 180°C for 2 hours.

6. The process for preparing the toughened modified epoxy resin according to claim 1, characterized in that: In the step (3), the molar concentration of tetravinylcyclotetrasiloxane and m-chloroperoxybenzoic acid is 1:4.5-5.

7. The process for preparing the toughened modified epoxy resin according to claim 1, characterized in that: In the step (4), the molar ratio of tetraepoxycyclotetrasiloxane to naphthylamine is 1:4-5.

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