Nitrogen-phosphorus flame-retardant epoxy resin curing agent, epoxy resin prepreg and carbon fiber composite material

Abstract

The invention discloses a nitrogen-phosphorus flame-retardant epoxy resin curing agent, an epoxy resin prepreg and a carbon fiber composite material. The nitrogen-phosphorus flame-retardant epoxy resin curing agent contains benzene ring groups and nitrogen and phosphorus elements; by adopting the curing agent with a specific structure, the curing time of the epoxy resin at normal temperature is relatively long, the epoxy resin can be rapidly cured at high temperature, the operability time of preparing the carbon fiber composite material is prolonged, and nitrogen and phosphorus elements in the molecular structure of the curing agent can improve the flame retardant property of the epoxy resin; the prepared epoxy resin prepreg has high fire resistance.

Description

Technical Field

[0001] The invention belongs to the field of epoxy resin curing agents, and in particular relates to a nitrogen-phosphorus flame-retardant epoxy resin curing agent, an epoxy resin prepreg and a carbon fiber composite material. Background Art

[0002] The power batteries of new energy vehicles have the risk of spontaneous combustion, which is characterized by rapid combustion, high heat, unpredictability and difficulty in extinguishing. The fire protection of new energy vehicle battery packs mainly relies on fireproof felt materials, such as insulation blankets, mica boards, etc. Although these materials can effectively insulate and control fire, they also have problems such as increased vehicle weight, poor heat dissipation and construction limitations. Therefore, in order to meet the safety and lightweight requirements of power batteries, prepregs with excellent flame retardant properties are becoming the first choice.

[0003] Traditional prepregs use halogen-type flame retardants, which have the characteristics of good flame retardant effect, low dosage, and little impact on mechanical properties. They have always been the main flame retardant for flame retardant materials. However, halogen flame retardants are prone to produce thick smoke, dioxins and hydrogen halides when burned, which limits their application in new energy vehicles. Therefore, it is an urgent problem to develop an environmentally friendly and highly fireproof prepreg for battery box covers and energy storage battery boxes of electric vehicles to meet the growing safety needs. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a nitrogen-phosphorus flame-retardant epoxy resin curing agent, an epoxy resin prepreg and a carbon fiber composite material. The present invention adopts a curing agent with a specific structure. The curing agent can cure the epoxy resin for a long time at room temperature and can quickly cure the epoxy resin at a high temperature, thereby extending the operability time for preparing the carbon fiber composite material. In addition, the nitrogen and phosphorus elements in the molecular structure of the curing agent can improve the flame retardant properties of the epoxy resin, so that the prepared epoxy resin prepreg has high fire resistance.

[0005] The object of the present invention is to provide a nitrogen-phosphorus flame-retardant epoxy resin curing agent, the structure of the nitrogen-phosphorus flame-retardant epoxy resin curing agent is as follows:

[0006] .

[0007] Another object of the present invention is to provide a method for preparing the nitrogen-phosphorus flame-retardant epoxy resin curing agent, comprising the following steps:

[0008] The 3-dimethoxyphosphorylbenzoic acid is amidated and then reacted with 4-aminophthalic anhydride to obtain the nitrogen-phosphorus flame-retardant epoxy resin curing agent.

[0009] In some embodiments of the present invention, the chlorination reagent is SOCl2.

[0010] In some embodiments of the present invention, the mass ratio of 3-dimethoxyphosphorylbenzoic acid to SOCl2 is 1:1.1~1.5.

[0011] In some embodiments of the present invention, the temperature of the acyl chlorination is 80-100° C. and the time is 15-20 h.

[0012] In some embodiments of the present invention, the mass ratio of 3-dimethoxyphosphorylbenzoic acid to 4-aminophthalic anhydride is 1:1-1.2.

[0013] In some embodiments of the present invention, the reaction temperature is 100-120° C. and the reaction time is 10-15 h.

[0014] Another object of the present invention is a method for preparing an epoxy resin prepreg, comprising the following steps:

[0015] The carbon fiber fabric is added into an acetone mixture of epoxy resin and the nitrogen-phosphorus flame-retardant epoxy resin curing agent for immersion, and the acetone is removed to obtain an epoxy resin prepreg.

[0016] In some embodiments of the present invention, the epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0017] In some embodiments of the present invention, the mass ratio of the carbon fiber fabric to the epoxy resin is 1.2-1.7:1.

[0018] In some embodiments of the present invention, the mass ratio of the epoxy resin to the nitrogen-phosphorus flame-retardant epoxy resin curing agent is 8-12:1.

[0019] Another object of the present invention is to provide a method for preparing an epoxy resin prepreg, comprising the following steps:

[0020] The carbon fiber fabric is added into an acetone mixture of epoxy resin, the nitrogen-phosphorus flame-retardant epoxy resin curing agent, an inorganic flame-retardant filler and a synergistic expansion flame retardant for immersion, and the acetone is removed to obtain an epoxy resin prepreg.

[0021] In some embodiments of the present invention, the mass ratio of the epoxy resin to the inorganic flame retardant filler and the synergistic intumescent flame retardant is 8-12: 0.2-0.5: 0.3-0.5.

[0022] In some embodiments of the present invention, the mass ratio of the carbon fiber fabric to the epoxy resin is 1.2-1.7:1.

[0023] In some embodiments of the present invention, the epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0024] In some embodiments of the present invention, the inorganic flame retardant filler is selected from at least one of aluminum hydroxide, magnesium hydroxide, kaolin, clay, montmorillonite, and diatomaceous earth.

[0025] In some preferred embodiments of the present invention, the inorganic flame retardant filler is selected from montmorillonite.

[0026] In some embodiments of the present invention, the synergistic intumescent flame retardant is selected from melamine.

[0027] Another object of the present invention is to provide a method for preparing a carbon fiber composite material, comprising the following steps:

[0028] The prepregs prepared by the preparation method of the epoxy resin prepregs are laid out in layers, and hot-pressed to obtain a carbon fiber composite material.

[0029] In some embodiments of the present invention, the temperature of the hot pressing molding is 160-200° C., the pressure is 0.2-0.6 MPa, and the time is 0.5-2 hours.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The epoxy prepreg of the present invention has high fire resistance. When subjected to heat, the surface can expand rapidly and absorb heat, effectively preventing high temperature from invading the interior of the battery, thereby achieving the purpose of fire prevention.

[0032] (2) The curing agent of the present invention plays a charring role. During combustion, a charcoal layer covering the substrate is generated on the surface. The charcoal layer is difficult to burn and plays a role in isolating oxygen, isolating heat transfer, and preventing the volatilization of combustible gases, thereby achieving the purpose of flame retardancy; the inorganic flame retardant filler plays a heat absorbing role. The flame retardant undergoes an endothermic reaction at high temperature, which reduces the temperature of the combustion area and achieves the flame retardant effect; the curing agent and the synergistic expansion flame retardant can generate a free radical scavenger to capture free radicals in the air, terminate the combustion chain reaction, and play a flame retardant role in the condensed phase and the gas phase; the curing agent and the inorganic flame retardant filler play a heat absorbing role, which reduces the temperature of the combustion area; the curing agent, the inorganic flame retardant filler and the synergistic expansion flame retardant cooperate with each other. The inorganic filler absorbs heat to dehydrate and dilute the combustible gas, and the curing agent reacts under heat to expand and flame retardant. The synergistic expansion flame retardant provides part of the carbon source and gas source to the curing agent during the combustion process, thereby improving the expansion efficiency and the expansion height, and forming a more solid expansion layer, thereby achieving an excellent flame retardant effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 .The flame retardant effect of the carbon fiber composite material of Example 12.

[0034] Figure 2 .The flame retardant effect of the carbon fiber composite material of Example 14. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with 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 should fall within the scope of protection of the present invention.

[0036] The structure of 3-dimethoxyphosphorylbenzoic acid is shown below:

[0037] ;

[0038] The structure of 4-aminophthalic anhydride is shown below:

[0039] ;

[0040] Bisphenol A epoxy resin adopts SM828 from Sanmu Group;

[0041] All raw materials of the present invention are conventionally commercially available.

[0042] Example 1

[0043] This embodiment provides a nitrogen-phosphorus flame-retardant epoxy resin curing agent, and the specific preparation process is as follows:

[0044] 10 parts by mass of 3-dimethoxyphosphorylbenzoic acid and 13 parts by mass of SOCl2 were added into a reaction bottle, 50 parts by mass of N,N-dimethylformamide was added, the mixture was reacted at 90°C for 18 hours, 11 parts by mass of 4-aminophthalic anhydride was added, the mixture was stirred for 1 hour, 1 mL of triethylamine was added, the mixture was reacted at 110°C for 12 hours, and a nitrogen-phosphorus flame-retardant epoxy resin curing agent was obtained.

[0045] The NMR structure of nitrogen-phosphorus flame-retardant epoxy resin curing agent is as follows:

[0046] 1 H NMR (400 MHz, CDCl3) δ 10.05 (s, 1H, NH), 8.57 (s, 1H, Ar), 8.43(s, 1H, Ar), 8.45 (s, 1H, Ar), 8.20-8.16 (m, 2H, Ar), 7.97(s, 1H, Ar), 7.69 (m, 1H, Ar), 3.82 (s, 6H, CH3).

[0047] Example 2

[0048] This embodiment provides a preparation of an epoxy resin, and the specific preparation process is as follows:

[0049] 80 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1 and 40 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure. The pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0050] Example 3

[0051] This embodiment provides a preparation of an epoxy resin, and the specific preparation process is as follows:

[0052] 120 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1 and 60 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure. The pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0053] Example 4

[0054] This embodiment provides a preparation of an epoxy resin, and the specific preparation process is as follows:

[0055] 80 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1, 5 parts by mass of aluminum hydroxide, 3 parts by mass of melamine and 40 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure, and the pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0056] Example 5

[0057] This embodiment provides a preparation of an epoxy resin, and the specific preparation process is as follows:

[0058] 120 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1, 2 parts by mass of diatomaceous earth, 5 parts by mass of melamine and 60 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure, and the pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0059] Example 6

[0060] This embodiment provides a preparation of an epoxy resin, and the specific preparation process is as follows:

[0061] 120 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1, 2 parts by mass of montmorillonite, 5 parts by mass of melamine and 60 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure, and the pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0062] Example 7

[0063] This embodiment provides a preparation of an epoxy resin, which differs from Embodiment 5 only in that it does not contain melamine. The specific preparation process is as follows:

[0064] 120 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1, 7 parts by mass of diatomaceous earth and 60 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure. The pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0065] Example 8

[0066] This embodiment provides a preparation of an epoxy resin, which differs from Embodiment 5 only in that diatomaceous earth is not contained. The specific preparation process is as follows:

[0067] 120 parts by mass of bisphenol A epoxy resin, 10 parts by mass of the nitrogen-phosphorus flame-retardant epoxy resin curing agent prepared in Example 1, 7 parts by mass of melamine and 60 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure. The pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0068] Example 9

[0069] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0070] The T700 carbon fiber fabric was added to the epoxy resin acetone mixture of Example 2 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.6 MPa, the hot-pressing temperature was 160°C, and the hot-pressing time was 2 hours to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.2:1 to obtain a carbon fiber composite material.

[0071] Example 10

[0072] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0073] The T700 carbon fiber fabric was added to the epoxy resin acetone mixture of Example 3 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.2 MPa, the hot-pressing temperature was 200°C, and the hot-pressing time was 0.5 hour to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.7:1 to obtain a carbon fiber composite material.

[0074] Embodiment 11

[0075] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0076] The T700 carbon fiber fabric was added to the epoxy resin acetone mixture of Example 4 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.6 MPa, the hot-pressing temperature was 160°C, and the hot-pressing time was 2 hours to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.2:1 to obtain a carbon fiber composite material.

[0077] Example 12

[0078] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0079] The T700 carbon fiber fabric was added to the epoxy resin-acetone mixture of Example 5 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.2 MPa, the hot-pressing temperature was 200°C, and the hot-pressing time was 0.5 hour to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.7:1 to obtain a carbon fiber composite material.

[0080] Embodiment 13

[0081] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0082] The T700 carbon fiber fabric was added to the epoxy resin acetone mixture of Example 6 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.2 MPa, the hot-pressing temperature was 200°C, and the hot-pressing time was 0.5 hour to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.7:1 to obtain a carbon fiber composite material.

[0083] Embodiment 14

[0084] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0085] The T700 carbon fiber fabric was added to the epoxy resin acetone mixture of Example 7 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.2 MPa, the hot-pressing temperature was 200°C, and the hot-pressing time was 0.5 hour to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.7:1 to obtain a carbon fiber composite material.

[0086] Embodiment 15

[0087] This embodiment provides an epoxy resin prepreg and a carbon fiber composite material, and the specific preparation process is as follows:

[0088] The T700 carbon fiber fabric was added to the epoxy resin acetone mixture of Example 8 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.2 MPa, the hot-pressing temperature was 200°C, and the hot-pressing time was 0.5 hour to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.7:1 to obtain a carbon fiber composite material.

[0089] Comparative Example 1

[0090] This comparative example provides a preparation of an epoxy resin, which differs from Example 3 only in that the curing agent is different. The specific preparation process is as follows:

[0091] 120 parts by mass of bisphenol A epoxy resin, 10 parts by mass of 4-aminophthalic anhydride and 60 parts by mass of acetone were mixed and stirred evenly. The acetone was removed by distillation under reduced pressure. The pot life of the obtained epoxy resin at room temperature was tested. The results are shown in Table 1.

[0092] Comparative Example 2

[0093] This comparative example provides an epoxy resin prepreg and a carbon fiber composite material, which is different from Example 8 only in that the epoxy resin acetone mixture used is different. The specific preparation process is as follows:

[0094] The T700 carbon fiber fabric was added to the epoxy resin-acetone mixture of Comparative Example 1 for immersion, and the acetone was removed to obtain an epoxy resin prepreg. Five layers of epoxy resin prepreg were laid and hot-pressed. The hot-pressing pressure was 0.2 MPa, the hot-pressing temperature was 200°C, and the hot-pressing time was 0.5 hour to obtain a carbon fiber composite material. The mass ratio of epoxy resin to T700 carbon fiber fabric was 1.7:1 to obtain a carbon fiber composite material.

[0095] Performance Test:

[0096] The limiting oxygen index (LOI) performance test reference standard ASTMD2863-2012, the standard size of the test specimen is 130mm×6.5mm×3.2mm, and the ignition method is central top ignition.

[0097] The vertical burning test (UL-94) performance test reference standard is ASTM D3801-2010, each group of 5 vertical burning test specimens, the standard size is 130mm × 12.7mm × 3.2mm, and each specimen is subjected to two 10-second flames during the test.

[0098] The bending performance test refers to the three-point bending test in the ASTM D7264 standard.

[0099] The tensile strength test was conducted in accordance with the standard GB / T 1447-2005.

[0100] Table 1. Pot life of the epoxy resins of Examples 2 to 8 and Comparative Example 1 at room temperature.

[0101] sample Applicable period at room temperature (days) Example 2 25 Example 3 24 Example 4 23 Example 5 26 Example 6 24 Example 7 24 Example 8 25 Comparative Example 1 5

[0102] It can be seen from Table 1 that the epoxy of the present invention has a long pot life at room temperature.

[0103] Table 2. Performance test results of carbon fiber composite materials of Examples 9 to 15 and Comparative Example 2.

[0104] sample Limiting oxygen index (%) UL-94 flame retardant grade Bending strength(Mpa) Tensile strength(Mpa) Example 9 30.5 V-0 998.4 561 Example 10 30.8 V-0 100.1 556 Embodiment 11 39.2 V-0 1260.5 622 Example 12 39.4 V-0 1261.2 619 Embodiment 13 39.5 V-0 1261.6 685 Embodiment 14 36.7 V-0 1112.3 620 Embodiment 15 36.9 V-0 1113.8 612 Comparative Example 2 20.8 No level 993.7 557

[0105] It can be seen from Table 2 that the curing agent of the present invention can improve the flame retardant properties of the epoxy resin, so that the prepared epoxy resin prepreg has high fire resistance; by comparing Examples 11-12 with Examples 14-15, it can be seen that the inorganic flame retardant filler and the synergistic expansion flame retardant can synergistically enhance the flame retardant effect of the curing agent, and the three work together to make the epoxy resin prepreg of the present invention have high fire resistance.

[0106] Depend on Figure 1 It can be seen that by adding the synergistic intumescent flame retardant, the surface is fully expanded. According to the proportion of the compound system, the expansion height of 30-50mm can be achieved. The carbon layer fully protects the main structure, and the back temperature is about 200℃.

[0107] Depend on Figure 2 It can be seen that without the addition of a synergistic intumescent flame retardant, the surface expands slightly, the height is <10 mm, efficient fire protection cannot be achieved, the char layer cannot be protected, it is easy to burn through, and the back temperature is >400°C.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the specification of this application, the technicians can still modify or replace the specific implementation mode of the present invention with equivalents, but these modifications or changes do not deviate from the scope of protection of the pending claims of the present application.

Claims

1. A nitrogen-phosphorus flame-retardant epoxy resin curing agent, characterized in that: The structure of the nitrogen-phosphorus flame-retardant epoxy resin curing agent is as follows: 。 2. The method for preparing the nitrogen-phosphorus flame-retardant epoxy resin curing agent according to claim 1, characterized in that: The steps include: The 3-dimethoxyphosphorylbenzoic acid is amidated and then reacted with 4-aminophthalic anhydride to obtain the nitrogen-phosphorus flame-retardant epoxy resin curing agent.

3. The method for preparing the nitrogen-phosphorus flame-retardant epoxy resin curing agent according to claim 2, characterized in that: The reagent for the chlorination is SOCl2; The mass ratio of 3-dimethoxyphosphorylbenzoic acid to SOCl2 is 1:1.1-1.5; The temperature of the chlorination is 80-100°C and the time is 15-20h; The mass ratio of 3-dimethoxyphosphorylbenzoic acid to 4-aminophthalic anhydride is 1:1-1.2; The reaction temperature is 100-120° C. and the reaction time is 10-15 hours.

4. A method for preparing an epoxy resin prepreg, characterized in that: The steps include: The carbon fiber fabric is added into an acetone mixture of epoxy resin and the nitrogen-phosphorus flame-retardant epoxy resin curing agent according to claim 1 for immersion, and the acetone is removed to obtain an epoxy resin prepreg.

5. The method for preparing the epoxy resin prepreg according to claim 4, characterized in that: The epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin.

6. The method for preparing the epoxy resin prepreg according to claim 4, characterized in that: The mass ratio of the epoxy resin to the nitrogen-phosphorus flame-retardant epoxy resin curing agent is 8-12:

1.

7. A method for preparing an epoxy resin prepreg, characterized in that: The steps include: The carbon fiber fabric is added to an acetone mixture of epoxy resin, the nitrogen-phosphorus flame-retardant epoxy resin curing agent according to claim 1, an inorganic flame-retardant filler and a synergistic expansion flame retardant for immersion, and the acetone is removed to obtain an epoxy resin prepreg.

8. The method for preparing the epoxy resin prepreg according to claim 7, characterized in that: The mass ratio of the epoxy resin to the inorganic flame retardant filler and the synergistic expansion flame retardant is 8-12: 0.2-0.5: 0.3-0.

5.

9. The method for preparing the epoxy resin prepreg according to claim 7, characterized in that: The epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin and novolac epoxy resin; The inorganic flame retardant filler is selected from at least one of aluminum hydroxide, magnesium hydroxide, kaolin, clay, montmorillonite and diatomaceous earth; The synergistic intumescent flame retardant is selected from melamine.

10. A method for preparing a carbon fiber composite material, characterized in that: The steps include: The prepregs prepared by the preparation method of the epoxy resin prepregs according to any one of claims 4 to 9 are laid out in layers, and hot-pressed to obtain a carbon fiber composite material.

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