Toughened modified epoxy resin material and preparation method thereof

Abstract

The invention relates to a toughened modified epoxy resin material and a preparation method thereof, and belongs to the technical field of high polymer materials. The toughened modified epoxy resin material comprises the following components in parts by weight: 90-120 parts of epoxy resin, 8-25 parts of a curing agent, 1-3 parts of a diluent, 0.5-5 parts of a curing accelerator, 4-18 parts of graphite, 5-15 parts of a modified toughening agent and 1-5 parts of a modified flame retardant, in the modified flexibilizer, a benzene ring and carbonyl of a polyimide structure endow the material with excellent heat resistance, intertwining between chains is avoided, embrittlement is avoided, the material and polyurethane are synergistically toughened, and a flexible-Si-O-Si-chain segment relieves thermal stress generated in the resin and improves the tensile strength; benzoxazine in the modified flame retardant contains a nitrogen element, releases non-combustible gas during combustion, forms a carbon layer at high temperature and covers the surface of the material, so that the flame retardance is improved; the toughened and modified epoxy resin material prepared by the invention not only has good toughening and heat-resisting effects, but also has an excellent flame-retardant effect.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a toughened modified epoxy resin material and its preparation method. Background Technology

[0002] Epoxy resin is an important thermosetting resin with excellent mechanical properties, adhesion, abrasion resistance, electrical insulation, as well as good dimensional and chemical stability. It is also easy to process and inexpensive, and is widely used in coatings, adhesives, machinery, construction, electrical and electronic insulation materials, and aerospace.

[0003] However, due to the high crosslinking density and three-dimensional network structure of epoxy resin after curing, it suffers from high internal stress, brittleness, poor heat resistance and impact resistance, resulting in low shear strength and low crack strain, which greatly limits its application in high-tech fields. In addition, although epoxy resin materials themselves have a certain degree of flame retardancy, with the continuous improvement of practical application requirements, their own flame retardancy is no longer sufficient to meet current needs. Therefore, the development of epoxy resin materials with excellent toughening modification has important practical significance and application value. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a toughened modified epoxy resin material and its preparation method.

[0005] The objective of this invention can be achieved through the following technical solutions: A toughened modified epoxy resin material and its preparation method, comprising the following raw materials in parts by weight: 90-120 parts epoxy resin, 8-25 parts curing agent, 1-3 parts diluent, 0.5-5 parts curing accelerator, 4-18 parts graphite, 5-15 parts modified toughening agent, and 1-5 parts modified flame retardant. The curing agent is 4,4'-diaminodiphenylmethane; The diluent is butyl glycidyl ether; The curing accelerator is 2-methylimidazole.

[0006] The modified toughening agent is prepared by the following method: Step A1: Mix 3-aminopropyltriethoxysilane and N-methylpyrrolidone at 0°C under nitrogen protection, stir until homogeneous, then add 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and stir at 0-15°C for 1 hour to obtain the intermediate. Furthermore, the ratio of 3-aminopropyltriethoxysilane, N-methylpyrrolidone, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 0.01-0.03 mol: 5 mL: 0.01-0.03 mol; The intermediate was prepared by reacting the amino groups of 3,3',4,4'-benzophenone tetracarboxylic dianhydride and 3-aminopropyltriethoxysilane. Step A2: Mix the intermediate and the ethanol-water mixture at 35°C for 10 min, then add tetrahydrofuran and triethylamine and react in an ice-water bath for 12 h. Add dichlorodiphenylsilane and mix. After the reaction is complete, filter and rotary evaporate to obtain the preproduct. Furthermore, the ratio of the intermediate, ethanol-water mixed solution, tetrahydrofuran, triethylamine, and dichlorodiphenylsilane is 0.01-0.03 mol: 150 mL: 0.01-0.03 mol: 100 mL: 14 mL, and the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Secondly, the preproduct is prepared by reacting the silanol groups generated from the hydrolysis of the intermediate with the chlorine atoms of dichlorodiphenylsilane. Step A3: Mix the preproduct and dibutyltin dilaurate evenly, stir at 100 r / min for 10 min in an oil bath at 60℃, then add isophorone diisocyanate, heat to 80-85℃, stir at 400-500 r / min for 30 min, after the reaction is complete, cool to room temperature, wash, filter, and dry to obtain the modified toughening agent. Furthermore, the ratio of the preproduct, dibutyltin dilaurate, and isophorone diisocyanate is 0.01-0.03 mol: 1-5 mL: 0.01-0.03 mol; Finally, the modified toughening agent was prepared by reacting the hydroxyl groups of the preproduct with the isocyanate groups of isophorone diisocyanate.

[0007] The modified flame retardant described above is prepared by the following method: Step B1: Eugenol, aniline and paraformaldehyde are mixed evenly, then toluene is added and mixed. The mixture is refluxed under nitrogen for 6 hours, cooled to room temperature, washed, rotary evaporated, and dried in a vacuum drying oven at 35°C for 12 hours to obtain the compound. Furthermore, the ratio of eugenol, aniline, paraformaldehyde, and toluene is 0.01-0.03 mol: 0.01-0.03 mol: 0.02-0.06 mol: 60-300 mL; The compound was prepared by first reacting eugenol with the amino group of aniline to form benzoxazine; Step B2: Mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, N,N-dimethylformamide and the compound evenly, stir at 140°C for 9 hours, filter, wash, and vacuum dry at 60°C to obtain the modified flame retardant. Furthermore, the ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, N,N-dimethylformamide, and the compound is 0.01-0.03 mol: 20-70 mL: 0.01-0.03 mol; Finally, the modified flame retardant was prepared by reacting the carbon-carbon double bond of the compound with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0008] A method for preparing a toughened modified epoxy resin material specifically includes the following steps: S1. Mix epoxy resin, diluent and curing accelerator evenly, then add graphite, modified toughening agent and modified flame retardant and mix and stir to obtain a mixture. S2. Mix the mixture and curing agent, vacuum degas the mixture, and pour it into a mold after the bubbles have completely disappeared. Heat the mixture to cure it and cool it to room temperature to obtain the toughened modified epoxy resin material.

[0009] The beneficial effects of this invention are: The toughened modified epoxy resin material of the present invention has good toughening and heat resistance effects, and also has excellent flame retardant effect, further extending its service life.

[0010] The modified toughening agent prepared in this invention reacts with the amino groups of 3-aminopropyltriethoxysilane and 3,3',4,4'-benzophenone tetracarboxylic dianhydride to form a polyimide structure. The benzene ring and carbonyl structure in the molecule endow the material with excellent heat resistance and makes it difficult to crystallize. There is no chain entanglement and the free volume is large, thus exhibiting excellent toughness and molecular mobility at high temperatures, effectively avoiding embrittlement and significantly improving the toughness of epoxy resin materials. In addition, the flexible -Si-O-Si- segments in the modified toughening agent, due to their high bond energy and large bond angle, not only maintain their own stability but also alleviate the thermal stress generated in the resin due to temperature drop, thereby improving the tensile strength of the resin and comprehensively optimizing the toughness of epoxy resin materials. Furthermore, the hydroxyl groups of the preproduct react with the isocyanate groups of isophorone diisocyanate to form polyurethane. Its unique soft and hard segment structure combines the high strength of plastics and the high elasticity of rubber. After being introduced into the epoxy resin network, it effectively solves the problems of high crosslinking density and high brittleness, significantly improving toughness.

[0011] In the modified flame retardant prepared by this invention, eugenol is a bio-based phenolic compound extracted from the natural plant clove. The benzoxazine formed by its reaction with aniline contains nitrogen and releases non-flammable gases during combustion, diluting the oxygen concentration and inhibiting flame spread. At high temperatures, benzoxazine decomposes to form a char layer that covers the material surface, isolating oxygen and heat transfer to prevent combustion. Simultaneously, the rigid benzene ring structure in the benzoxazine molecule, after participating in the cross-linking reaction, can increase the cross-linking density of the resin, giving it excellent stability and flame retardancy. Furthermore, the phosphorus-nitrogen flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, as a phosphoraphenanthrene compound with high thermal stability, promotes the formation of a dense and continuous char layer during combustion, isolating oxygen and blocking the exchange of heat and combustible gases, inhibiting combustion. It also synergistically retards with the phosphorus-oxygen double bond, further improving flame retardant efficiency. In addition, the modified flame retardant prepared by this invention is halogen-free, helping to reduce environmental pollution and ecosystem damage, is harmless to human health, and achieves sustainable development. Detailed Implementation

[0012] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] Example 1: A method for preparing a toughened modified epoxy resin material, specifically including the following steps: S1. Weigh the raw materials according to the following parts by weight: 90 parts epoxy resin, 8 parts curing agent, 1 part diluent, 0.5 parts curing accelerator, 4 parts graphite, 5 parts modified toughening agent (prepared in this embodiment), and 1 part modified flame retardant (prepared in this embodiment); mix the epoxy resin, butyl glycidyl ether and 2-methylimidazole evenly, then add graphite, modified toughening agent and modified flame retardant and mix and stir to obtain a mixture. S2. Mix the mixture with 4,4'-diaminodiphenylmethane, vacuum degas the mixture, and pour it into a mold after the bubbles have completely disappeared. Heat the mixture to cure it and cool it to room temperature to obtain the toughened modified epoxy resin material. The modified toughening agent is prepared by the following method: Step A1: Mix 0.01 mol of 3-aminopropyltriethoxysilane and 5 mL of N-methylpyrrolidone at 0 °C under nitrogen protection, stir until homogeneous, then add 0.01 mol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and stir at 0 °C for 1 h to obtain the intermediate. Step A2: Mix 0.01 mol of intermediate and 150 mL of ethanol-water mixture at 35 °C for 10 min, then add 0.01 mol of tetrahydrofuran and 100 mL of triethylamine and react in an ice-water bath for 12 h. Add 14 mL of dichlorodiphenylsilane and mix. After the reaction is complete, filter and rotary evaporate to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixture is 4:1. Step A3: Mix 0.01 mol of the preproduct and 1 mL of dibutyltin dilaurate evenly, stir at 100 r / min for 10 min in an oil bath at 60 °C, then add 0.01 mol of isophorone diisocyanate, heat to 80 °C, stir at 400 r / min for 30 min, after the reaction is complete, cool to room temperature, wash, filter, and dry to obtain the modified toughening agent; The modified flame retardant described above is prepared by the following method: Step B1: Mix 0.01 mol eugenol, 0.01 mol aniline and 0.02 mol paraformaldehyde evenly, then add 60 mL toluene and mix. Reflux under nitrogen for 6 h, cool to room temperature, wash, rotary evaporate, and dry in a vacuum drying oven at 35 °C for 12 h to obtain the compound. Step B2: Mix 0.01 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 20 mL of N,N-dimethylformamide and 0.01 mol of the compound evenly, stir at 140 °C for 9 h, filter, wash and dry under vacuum at 60 °C to obtain the modified flame retardant.

[0014] Example 2: A method for preparing a toughened modified epoxy resin material, specifically including the following steps: S1. Weigh the raw materials according to the following weight parts: 105 parts epoxy resin, 16 parts curing agent, 2 parts diluent, 3 parts curing accelerator, 11 parts graphite, 10 parts modified toughening agent (prepared in this embodiment), and 3 parts modified flame retardant (prepared in this embodiment); mix the epoxy resin, butyl glycidyl ether and 2-methylimidazole evenly, then add graphite, modified toughening agent and modified flame retardant and mix and stir to obtain a mixture. S2. Mix the mixture with 4,4'-diaminodiphenylmethane, vacuum degas the mixture, and pour it into a mold after the bubbles have completely disappeared. Heat the mixture to cure it and cool it to room temperature to obtain the toughened modified epoxy resin material. The modified toughening agent is prepared by the following method: Step A1: Mix 0.02 mol of 3-aminopropyltriethoxysilane and 5 mL of N-methylpyrrolidone at 0 °C under nitrogen protection, stir until homogeneous, then add 0.02 mol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and stir at 7 °C for 1 h to obtain the intermediate. Step A2: Mix 0.02 mol of intermediate and 150 mL of ethanol-water mixture at 35 °C for 10 min, then add 0.02 mol of tetrahydrofuran and 100 mL of triethylamine and react in an ice-water bath for 12 h. Add 14 mL of dichlorodiphenylsilane and mix. After the reaction is complete, filter and rotary evaporate to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixture is 4:1. Step A3: Mix 0.02 mol of the preproduct and 3 mL of dibutyltin dilaurate evenly, stir at 100 r / min for 10 min in an oil bath at 60 °C, then add 0.02 mol of isophorone diisocyanate, heat to 83 °C, stir at 450 r / min for 30 min, after the reaction is complete, cool to room temperature, wash, filter, and dry to obtain the modified toughening agent; The modified flame retardant described above is prepared by the following method: Step B1: Mix 0.02 mol eugenol, 0.02 mol aniline and 0.04 mol paraformaldehyde evenly, then add 180 mL toluene and mix. Reflux under nitrogen for 6 h, cool to room temperature, wash, rotary evaporate, and dry in a vacuum drying oven at 35 °C for 12 h to obtain the compound. Step B2: Mix 0.02 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 45 mL of N,N-dimethylformamide and 0.02 mol of the compound evenly, stir at 140 °C for 9 h, filter, wash and dry under vacuum at 60 °C to obtain the modified flame retardant.

[0015] Example 3: A method for preparing a toughened modified epoxy resin material, specifically including the following steps: S1. Weigh the raw materials according to the following parts by weight: 120 parts epoxy resin, 25 parts curing agent, 3 parts diluent, 5 parts curing accelerator, 18 parts graphite, 15 parts modified toughening agent (prepared in this embodiment), and 5 parts modified flame retardant (prepared in this embodiment); mix the epoxy resin, butyl glycidyl ether, and 2-methylimidazole evenly, then add the graphite, modified toughening agent, and modified flame retardant and mix and stir to obtain a mixture. S2. Mix the mixture with 4,4'-diaminodiphenylmethane, vacuum degas the mixture, and pour it into a mold after the bubbles have completely disappeared. Heat the mixture to cure it and cool it to room temperature to obtain the toughened modified epoxy resin material. The modified toughening agent is prepared by the following method: Step A1: Mix 0.03 mol of 3-aminopropyltriethoxysilane and 5 mL of N-methylpyrrolidone at 0 °C under nitrogen protection, stir until homogeneous, then add 0.03 mol of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and stir at 15 °C for 1 h to obtain the intermediate. Step A2: Mix 0.03 mol of intermediate and 150 mL of ethanol-water mixed solution at 35 °C for 10 min, then add 0.03 mol of tetrahydrofuran and 100 mL of triethylamine and react in an ice-water bath for 12 h. Add 14 mL of dichlorodiphenylsilane and mix. After the reaction is complete, filter and rotary evaporate to obtain the preproduct. The volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1. Step A3: Mix 0.03 mol of the preproduct and 5 mL of dibutyltin dilaurate evenly, stir at 100 r / min for 10 min in an oil bath at 60 °C, then add 0.03 mol of isophorone diisocyanate, heat to 85 °C, stir at 500 r / min for 30 min, after the reaction is complete, cool to room temperature, wash, filter, and dry to obtain the modified toughening agent; The modified flame retardant described above is prepared by the following method: Step B1: Mix 0.03 mol eugenol, 0.03 mol aniline and 0.06 mol paraformaldehyde evenly, then add 300 mL toluene and mix. Reflux under nitrogen for 6 h, cool to room temperature, wash, rotary evaporate, and dry in a vacuum drying oven at 35 °C for 12 h to obtain the compound. Step B2: Mix 0.03 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 70 mL of N,N-dimethylformamide and 0.03 mol of the compound evenly, stir at 140 °C for 9 h, filter, wash and dry under vacuum at 60 °C to obtain the modified flame retardant.

[0016] Comparative Example 1: This comparative example is a toughened modified epoxy resin material. The difference between this example and Example 3 is that an equal amount of polybutadiene is used instead of the modified toughening agent prepared in Example 3. All other aspects are the same.

[0017] Comparative Example 2: This comparative example is a toughened modified epoxy resin material. The difference between this example and Example 3 is that an equal amount of magnesium hydroxide is used instead of the modified flame retardant prepared in Example 3. All other aspects are the same.

[0018] Performance testing: The toughened modified epoxy resin materials prepared in Examples 1-3 and Comparative Examples 1-2 were cut into standard test sizes. Tensile strength was tested according to standard GB / T 2567, and flexural strength was tested according to GB / T 9341. Flame retardancy was tested according to ASTM D63577. The test results are shown in Table 1 below.

[0019] As can be seen from the test data in Table 1, the toughened modified epoxy resin material prepared by the present invention has good toughening and heat resistance effects. Table 1 also shows that the toughened modified epoxy resin material prepared by the present invention has good flame retardant effect and extends service life.

[0020] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a toughened modified epoxy resin material, characterized in that, Specifically, the following steps are included: S1. Weigh the raw materials according to the following parts by weight: 90-120 parts epoxy resin, 8-25 parts curing agent, 1-3 parts diluent, 0.5-5 parts curing accelerator, 4-18 parts graphite, 5-15 parts modified toughening agent, and 1-5 parts modified flame retardant; mix the epoxy resin, diluent, and curing accelerator evenly, then add the graphite, modified toughening agent, and modified flame retardant and mix and stir to obtain a mixture. S2. Mix the mixture and curing agent, vacuum degas the mixture, and pour it into a mold after the bubbles have completely disappeared. Heat the mixture to cure it and cool it to room temperature to obtain the toughened modified epoxy resin material. The modified toughening agent is prepared by the following method: Step A1: Mix 3-aminopropyltriethoxysilane and N-methylpyrrolidone at 0°C under nitrogen protection, stir until homogeneous, then add 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and stir at 0-15°C for 1 hour to obtain the intermediate. Step A2: Mix the intermediate and the ethanol-water mixture at 35°C for 10 min, then add tetrahydrofuran and triethylamine and react in an ice-water bath for 12 h. Add dichlorodiphenylsilane and mix. After the reaction is complete, filter and rotary evaporate to obtain the preproduct. Step A3: Mix the preproduct and dibutyltin dilaurate evenly, stir at 100 r / min for 10 min in an oil bath at 60℃, then add isophorone diisocyanate, heat to 80-85℃, stir at 400-500 r / min for 30 min, after the reaction is complete, cool to room temperature, wash, filter, and dry to obtain the modified toughening agent.

2. The method for preparing a toughened modified epoxy resin material according to claim 1, characterized in that, In step A1, the ratio of 3-aminopropyltriethoxysilane, N-methylpyrrolidone, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride is 0.01-0.03 mol: 5 mL: 0.01-0.03 mol.

3. The method for preparing a toughened modified epoxy resin material according to claim 1, characterized in that, In step A2, the ratio of the intermediate, ethanol-water mixture, tetrahydrofuran, triethylamine, and dichlorodiphenylsilane is 0.01-0.03 mol: 150 mL: 0.01-0.03 mol: 100 mL: 14 mL, and the volume ratio of ethanol to water in the ethanol-water mixture is 4:

1.

4. The method for preparing a toughened modified epoxy resin material according to claim 1, characterized in that, In step A3, the ratio of the preproduct, dibutyltin dilaurate, and isophorone diisocyanate is 0.01-0.03 mol: 1-5 mL: 0.01-0.03 mol.

5. The method for preparing a toughened modified epoxy resin material according to claim 1, characterized in that, The modified flame retardant is prepared by the following method: Step B1: Eugenol, aniline and paraformaldehyde are mixed evenly, then toluene is added and mixed. The mixture is refluxed under nitrogen for 6 hours, cooled to room temperature, washed, rotary evaporated, and dried in a vacuum drying oven at 35°C for 12 hours to obtain the compound. Step B2: Mix 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, N,N-dimethylformamide and the compound evenly, stir at 140℃ for 9 hours, filter, wash, and vacuum dry at 60℃ to obtain the modified flame retardant.

6. The method for preparing a toughened modified epoxy resin material according to claim 5, characterized in that, In step B1, the ratio of eugenol, aniline, paraformaldehyde, and toluene is 0.01-0.03 mol: 0.01-0.03 mol: 0.02-0.06 mol: 60-300 mL.

7. The method for preparing a toughened modified epoxy resin material according to claim 5, characterized in that, In step B2, the ratio of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, N,N-dimethylformamide, and the compound is 0.01-0.03 mol: 20-70 mL: 0.01-0.03 mol.

8. The method for preparing a toughened modified epoxy resin material according to claim 1, characterized in that, The curing agent is 4,4'-diaminodiphenylmethane, the diluent is butyl glycidyl ether, and the curing accelerator is 2-methylimidazole.

9. A toughened modified epoxy resin material, characterized in that, Prepared by the preparation method according to any one of claims 1-8.

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