Toughening modified flame-retardant epoxy resin composition, prepreg and preparation method thereof

Abstract

The invention discloses a toughened modified flame-retardant epoxy resin composition which is prepared by the following steps: S11, performing thermal reaction on 50-90 parts by weight of flame-retardant epoxy resin, 5-20 parts by weight of an epoxy diluent and 10-25 parts by weight of a toughening agent under the action of 0.01-0.5 part by weight of a catalyst to prepare toughened modified flame-retardant epoxy resin A; s12, heating and mixing 0-5 parts of an auxiliary agent, 10-40 parts of a flame retardant, 3-15 parts of a pigment and the toughened modified flame-retardant epoxy resin A, and then adding a chain extender for thermal reaction copolymerization to obtain toughened modified flame-retardant epoxy resin B; s13, mixing 1-10 parts of a latent curing agent and 1-6 parts of an accelerant with the toughening modified flame-retardant epoxy resin B to prepare a toughening modified flame-retardant epoxy resin composition; a composite material product prepared from the toughened modified flame-retardant epoxy resin composition and a fiber reinforcement can meet airworthiness standard requirements such as BMS8-2 Class3 Grade A TYPE 45 and the like, and is suitable for manufacturing of aircraft cargo hold wallboards.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials, specifically to a toughened modified flame-retardant epoxy resin composition, its preparation method, and a prepreg made from the composition. Background Technology

[0002] As a crucial component of the cargo hold structure, aircraft cargo hold bulkheads not only need to be lightweight and high-strength, but also must meet stringent requirements for flame retardancy and impact resistance. Cargo hold bulkheads are typically between 0.18mm and 1.78mm thick and are used for linings, panels, and other areas within the cargo hold; their performance directly affects the safety and service life of the aircraft.

[0003] Currently, commercial aircraft cargo hold panel materials must meet airworthiness standards such as BMS8-2 Class 3 Grade A Type 45, requiring materials to possess excellent mechanical properties while also exhibiting high flame retardancy and high impact resistance. While traditional epoxy resins possess excellent mechanical properties, they are brittle, have poor impact resistance, and do not inherently possess flame retardant characteristics. To improve flame retardancy, flame retardants, such as phosphorus-containing or phosphorus-nitrogen-based flame retardants, are typically added to epoxy resins, but this often further reduces the material's toughness. On the other hand, adding toughening agents (such as rubber-like materials) to improve impact resistance may compromise the material's flame retardant properties. Therefore, balancing flame retardancy and impact resistance has become a key challenge in the technological development of this field. Summary of the Invention

[0005] The present invention aims to provide a toughened modified flame-retardant epoxy resin composition and its prepreg, which solves the problem that epoxy resin materials in the prior art are difficult to simultaneously meet the requirements of high flame retardancy and high drop hammer impact resistance, so that it meets the airworthiness standards such as BMS8-2 Class 3 Grade A TYPE 45 and is suitable for the manufacture of aircraft cargo hold panels.

[0006] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution: A toughened and modified flame-retardant epoxy resin composition, comprising, by weight of raw materials: Toughened modified flame-retardant epoxy resin A, 80-120 parts; Additives, 0-5 parts; Flame retardant, 10-40 parts; Pigment: 3-15 parts; Latent curing agent, 1-10 parts; Accelerator, 1-6 parts; The toughened modified flame-retardant epoxy resin A comprises: Flame-retardant epoxy resin, 50-90 parts; Epoxy thinner, 5-20 parts; Toughening agent, 10-25 parts; Catalyst, 0.01-0.5 parts; It also includes a chain extender, wherein the chain extender comprises at least one of a monoamine and a polyamine; the monoamine is either a primary amino group or a secondary amino group; the polyamine comprises at least one primary amino group and / or one secondary amino group, and the molar ratio of the total amount of the primary amino group and / or the secondary amino group to the epoxy group in the toughened and modified flame retardant epoxy resin A is less than 0.3.

[0007] In another embodiment, the flame-retardant epoxy resin is selected from one or more of phosphorus-containing epoxy resin, phosphorus-nitrogen epoxy resin, phosphorus-containing phenolic epoxy resin, and phosphorus-nitrogen phenolic epoxy resin.

[0008] In another embodiment, the epoxy diluent is a monofunctional or difunctional epoxy reactive diluent with a linear molecular structure and containing any one or more groups selected from ether, ester, and hydroxyl groups.

[0009] In another embodiment, the toughening agent is nitrile rubber, wherein the nitrile rubber contains 15% to 40% acrylonitrile; and the catalyst is an organophosphorus compound, preferably triphenylphosphine.

[0010] In another embodiment, the flame retardant is selected from one or more of phosphorus-nitrogen type flame retardants, aluminum diethylphosphinate, hexaphenoxycyclotriphosphazene, melamine cyanate, and ammonium polyphosphate, and its powder particle size is ≤3μm.

[0011] In another embodiment, the pigment has a Mohs hardness of ≤3.5, a powder particle size of ≤3μm, and the color can be selected as needed. When used to prepare aircraft cargo hold panels, white is usually used.

[0012] In another embodiment, the latent curing agent is selected from at least one of aromatic amines, dicyandiamide, organic hydrazides, modified aromatic amines, modified dicyandiamide, modified organic hydrazides, and linear phenolic resins; the accelerator is selected from at least one of organic urea, modified organic urea, imidazole, and modified imidazole.

[0013] In another embodiment, the additives include any one or more of wetting agents, viscosity reducers, defoamers, and internal release agents.

[0014] The preparation method of the above-mentioned toughened modified flame-retardant epoxy resin composition includes the following steps: S11. According to the weight of raw materials, add 50-90 parts of flame-retardant epoxy resin, 10-25 parts of toughening agent, and 5-20 parts of epoxy diluent to the reactor. Under nitrogen protection, continue to add 0.01-0.5 parts of catalyst to the reactor, heat to 120-170℃ and stir for 1-4 hours to obtain toughened modified flame-retardant epoxy resin A. S12. Cool the toughened modified flame-retardant epoxy resin A to 80-130℃, add the additives, flame retardant, and pigment in parts by weight, mix thoroughly, add the chain extender, and react for 30-120 minutes to obtain the toughened modified flame-retardant epoxy resin B; the chain extender includes at least one of monoamines and polyamines; the monoamine is either a primary amino group or a secondary amino group; the polyamine includes at least one primary amino group and / or one secondary amino group; the molar ratio of the total amount of primary amino groups and / or secondary amino groups in the chain extender to the number of epoxy groups in the toughened modified flame-retardant epoxy resin A is less than 0.3; S13. Prepare a toughened modified flame-retardant epoxy resin composition; cool the toughened modified flame-retardant epoxy resin B to 60-90℃, add 1-10 parts of latent curing agent and 1-6 parts of accelerator according to the weight of the raw materials, mix and stir for 15-60 minutes to obtain the final toughened modified flame-retardant epoxy resin composition.

[0015] In step S11, the flame-retardant epoxy resin may be selected from one or more of phosphorus-containing epoxy resin, phosphorus-nitrogen epoxy resin, phosphorus-containing phenolic epoxy resin, and phosphorus-nitrogen phenolic epoxy resin; the epoxy diluent is a monofunctional or bifunctional epoxy reactive diluent with a linear molecular structure containing ether, ester, or hydroxyl groups; the toughening agent is preferably nitrile rubber with an acrylonitrile content of 15% to 40%; and the catalyst is preferably an organophosphorus compound, such as triphenylphosphine.

[0016] In step S12, the flame retardant is selected from one or more of phosphorus-nitrogen type flame retardants, aluminum diethylphosphinate, hexaphenoxycyclotriphosphazene, melamine cyanate, and ammonium polyphosphate, with a powder particle size ≤3μm; the pigment has a Mohs hardness ≤3.5 and a powder particle size ≤3μm.

[0017] In step S13, the latent curing agent may be selected from at least one of aromatic amines, dicyandiamide, organic hydrazides, modified aromatic amines, modified dicyandiamides, modified organic hydrazides, and linear phenolic resins; the accelerator may be selected from at least one of organic urea, modified organic urea, imidazole, and modified imidazole.

[0018] The present invention also provides a prepreg for aircraft cargo hold panels, which is made into a film by the above-mentioned toughened modified flame retardant epoxy resin composition and impregnated with fiber reinforcement, wherein the resin composition content is 36±3%.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) High flame retardant performance: meets the requirements of 60 seconds vertical combustion, 30 seconds 45 degrees combustion and flame penetration resistance in BMS8-2 standard, the char length is controlled within 12.7cm, and there is no dripping phenomenon; (2) Excellent resistance to falling hammer impact: while retaining flame retardant performance, the product can resist the impact of a 5.8kg falling hammer weighing more than 18 inches within a thickness range of 1.14±0.1mm, and the maximum impact height can reach 27 inches, which is significantly better than the comparative example; (3) Good mechanical properties: the tensile strength can reach 563MPa, the bending strength can reach 307MPa, the edge extrusion strength can reach 268MPa, and the comprehensive mechanical properties are excellent; (4) Strong process adaptability: adopts step reaction process, the components have good compatibility, the preparation process is stable, and it is suitable for industrial production. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0021] Unless otherwise specified, all raw materials used in this invention can be purchased commercially or prepared using conventional methods.

[0022] A toughened and modified flame-retardant epoxy resin composition, comprising, by weight of raw materials: Toughened modified flame-retardant epoxy resin A, 80-120 parts; Additives, 0-5 parts; Flame retardant, 10-40 parts; Pigment: 3-15 parts; Latent curing agent, 1-10 parts; Accelerator, 1-6 parts; The toughened modified flame-retardant epoxy resin A comprises: Flame-retardant epoxy resin, 50-90 parts; Epoxy thinner, 5-20 parts; Toughening agent, 10-25 parts; Catalyst, 0.01-0.5 parts; It also includes a chain extender, wherein the chain extender comprises at least one of a monoamine and a polyamine; the monoamine is either a primary amino group or a secondary amino group; the polyamine comprises at least one primary amino group and / or one secondary amino group, and the molar ratio of the total amount of the primary amino group and / or the secondary amino group to the epoxy group in the toughened and modified flame retardant epoxy resin A is less than 0.3.

[0023] The flame-retardant epoxy resin is selected from one or more of phosphorus-containing epoxy resin, phosphorus-nitrogen epoxy resin, phosphorus-containing phenolic epoxy resin, and phosphorus-nitrogen phenolic epoxy resin.

[0024] The epoxy diluent is a monofunctional or difunctional epoxy reactive diluent with a linear molecular structure and containing ether, ester, and hydroxyl groups.

[0025] The toughening agent is nitrile rubber, and the acrylonitrile content in the nitrile rubber is 15% to 40%; the catalyst is an organophosphorus compound.

[0026] The flame retardant is selected from one or more of phosphorus-nitrogen type flame retardants, aluminum diethylphosphinate, hexaphenoxycyclotriphosphazene, melamine cyanate, and ammonium polyphosphate, and its powder particle size is ≤3μm.

[0027] The pigment has a Mohs hardness of ≤3.5, a powder particle size of ≤3μm, and the color can be selected as needed. As a resin composition for preparing aircraft cargo hold panels, white is usually selected.

[0028] The chain extender includes at least one of monoamines and polyamines; the monoamine is either a primary amino group or a secondary amino group; the polyamine includes at least one primary amino group and / or one secondary amino group; the molar ratio of the total amount of primary amino groups and / or secondary amino groups in the chain extender to the number of epoxy groups in the toughened and modified flame-retardant epoxy resin A is less than 0.3.

[0029] The latent curing agent is selected from at least one of aromatic amines, dicyandiamide, organic hydrazides, modified aromatic amines, modified dicyandiamide, modified organic hydrazides, and linear phenolic resins; the accelerator is selected from at least one of organic urea, modified organic urea, imidazole, and modified imidazole.

[0030] The preparation method of the above-mentioned toughened modified flame-retardant epoxy resin composition includes the following steps: S11. According to the weight of raw materials, add 50-90 parts of preheated flame-retardant epoxy resin and 10-25 parts of toughening agent to the reactor, then add 5-20 parts of epoxy diluent, add 0.01-0.5 parts of catalyst under nitrogen protection, heat to 120-170℃ and stir for 1-4 hours to obtain toughened modified flame-retardant epoxy resin A. S12. Cool the toughened modified flame-retardant epoxy resin A to 80-130℃, add 0-5 parts of additives, 10-40 parts of flame retardant, and 3-15 parts of pigment according to the weight of the raw materials, mix evenly, then add chain extender, and react for 30-120 minutes to obtain toughened modified flame-retardant epoxy resin B; the chain extender includes at least one of monoamines and polyamines; the monoamine is either a primary amino group or a secondary amino group; the polyamine includes at least one primary amino group and / or one secondary amino group; the molar ratio of the total amount of primary amino groups and / or secondary amino groups in the chain extender to the epoxy groups in the toughened modified flame-retardant epoxy resin A is less than 0.3; S13. Prepare a toughened modified flame-retardant epoxy resin composition; cool the toughened modified flame-retardant epoxy resin B to 60-90℃, add 1-10 parts of latent curing agent and 1-6 parts of accelerator according to the weight of the raw materials, mix and stir for 15-60 minutes to obtain the final toughened modified flame-retardant epoxy resin composition.

[0031] In step S11, the flame-retardant epoxy resin may be selected from one or more of phosphorus-containing epoxy resin, phosphorus-nitrogen epoxy resin, phosphorus-containing phenolic epoxy resin, and phosphorus-nitrogen phenolic epoxy resin; the epoxy diluent is a monofunctional or bifunctional epoxy reactive diluent with a linear molecular structure containing ether, ester, or hydroxyl groups; the toughening agent is preferably nitrile rubber with an acrylonitrile content of 15% to 40%; and the catalyst is preferably an organophosphorus compound, such as triphenylphosphine.

[0032] In step S12, the flame retardant is selected from one or more of phosphorus-nitrogen type flame retardants, aluminum diethylphosphinate, hexaphenoxycyclotriphosphazene, melamine cyanate, and ammonium polyphosphate, with a powder particle size ≤3μm; the pigment has a Mohs hardness ≤3.5 and a powder particle size ≤3μm; the chain extender is a monoamine or polyamine having primary and / or secondary amino groups, and the molar ratio of the total amount of primary and secondary amino groups to the epoxy groups in the toughened modified flame retardant epoxy resin A is less than 0.3; In step S13, the latent curing agent may be selected from at least one of aromatic amines, dicyandiamide, organic hydrazides, modified aromatic amines, modified dicyandiamides, modified organic hydrazides, and linear phenolic resins; the accelerator may be selected from at least one of organic urea, modified organic urea, imidazole, and modified imidazole.

[0033] The present invention also provides a prepreg for aircraft cargo hold panels, which is made into a film by the above-mentioned epoxy resin composition and impregnated with fiber reinforcement, wherein the resin composition content is 36±3%.

[0034] The present invention will now be described in more detail through examples and comparative examples. Example 1

[0035] A prepreg for aircraft cargo hold wall panels is provided, comprising: S1. Preparation of toughened modified flame-retardant epoxy resin composition, specifically including the following steps: S11. Take 75g of phosphorus-containing epoxy resin A2334, 12g of epoxy diluent XY-622, and 13g of toughening agent CTBN and place them in a reaction vessel. Turn on the stirring and introduce nitrogen gas for protection. Then add 0.05g of triphenylphosphine catalyst. Raise the temperature of the reaction vessel to 130℃ and react for 3 hours to obtain toughened modified flame retardant epoxy resin A. S12. After cooling the toughened modified flame retardant epoxy resin A to 100℃, add 0.5g of additive BYK-W9010, 20g of flame retardant and 10g of pigment and mix evenly. After there is no obvious particle feel, add 1g of chain extender D230 and continue to react for 1 hour to obtain toughened modified flame retardant epoxy resin B. S13. Cool the toughened and modified flame-retardant epoxy resin to 70°C, add 5g of latent curing agent DICY and 2g of accelerator UR-500, mix and stir for 30 minutes to obtain the toughened and modified flame-retardant epoxy resin composition. Step S2: Prepreg preparation. Specifically, the toughened modified flame-retardant epoxy resin composition is placed in a coating machine at a coating temperature of 70°C to prepare a 78.75 g / m² film. The resulting film is drawn out from the upper and lower unwinding devices of the prepreg laminating machine and forms a sandwich structure with SW280 high-strength glass fiber. It is then impregnated by a composite heating roller at a composite temperature of 85°C. After impregnation, it is cooled and covered with a PE film. The film is then wound up to obtain a prepreg with a resin content of 36% and a fiber basis weight of 280 g / m².

[0036] In the above steps, for raw materials with high viscosity that are difficult to transfer (such as phosphorus-containing epoxy resins, toughening agents, etc.), the viscosity can be reduced by preheating, thus reducing the difficulty of transfer.

[0037] Examples 2-6 The prepreg materials for aircraft cargo hold panels provided in Examples 2-6 are prepared using the same steps as those in Example 1. The difference lies in the adjustment of process parameters such as raw material composition and weight parts, as well as reaction conditions. See Table 1 for details.

[0038] Table 1 Comparative Examples 1-6 As comparative examples, Comparative Examples 1-6 used commercially available toughened modified epoxy resins and flame-retardant resins to prepare toughened and flame-retardant epoxy resin compositions. The formulations of each component are shown in Table 2. The preparation steps are as follows: Step 1: According to the weight of the raw materials, place the flame-retardant epoxy resin, toughening agent, and epoxy diluent into a 130℃ reaction vessel, mix and stir thoroughly for 1 hour, add the additives, stir for 1 minute, then add the flame retardant and pigments, and continue mixing and stirring for 2 hours to ensure that the flame retardant is fully mixed, without powder agglomeration or other phenomena, and the texture is uniform. Step 2: After cooling the mixture from Step 1 to 70°C, add the latent curing agent and accelerator, and mix thoroughly for 30 minutes to obtain the toughened flame-retardant epoxy resin composition. Step 3: Prepreg preparation. Specifically, the toughened modified flame-retardant epoxy resin composition is placed in a coating machine at a coating temperature of 70℃ to prepare a 78.75 g / ㎡ film. The obtained film is drawn out from the upper and lower film devices of the prepreg laminating machine and forms a sandwich structure with high-strength glass fiber. It is then impregnated by a composite heating roller at a composite temperature of 85℃. After impregnation, it is cooled and covered with a PE film. The film is then wound up to obtain a prepreg with a resin content of 36% and a fiber basis weight of 280 g / ㎡.

[0039] Table 2 The prepregs prepared in Examples 1-6 and Comparative Examples 1-6 were cut and prepared into test panels. Specifically, each test panel consisted of five layers of prepreg. After being bagged and sealed, the panels were placed in an autoclave for curing. The curing process involved increasing the temperature at 10°C / min until it reached 125°C, maintaining a pressure of 6 Bar, and holding the pressure for 120 minutes to cure. After demolding, the test panels were machined with test strips according to BMS8-2 standards and then tested. The test data for the test panels prepared with the prepregs of Examples 1-6 are shown in Table 3, and the test data for the test panels prepared with the prepregs of Comparative Examples 1-6 are shown in Table 4.

[0040] Table 3 The data in Table 3 show that the test results of Examples 1-6 all meet the performance requirements of BMS8-2 Class 3 Grade A TYPE 45.

[0041] Table 4 Table 4 shows that, in Comparative Example 1, with the addition of high toughening materials, the combined EW300 glass fiber did not meet the standard requirements for drop hammer impact resistance and flame retardancy. In Comparative Example 2, with the addition of a large amount of toughening resin, the drop hammer impact resistance of more than 18 inches could be met, but due to the addition of a large amount of toughening materials, the rigidity of the composition decreased significantly, and the char length after 60s vertical burning exceeded the standard requirement of 12.7cm. In comparison examples 3-6, with the addition of less toughening resin and the increase of flame retardant resin content, the flame retardant performance was significantly improved, and the 60s vertical burning was passed, but the toughness was insufficient, and the drop hammer impact resistance decreased significantly, failing to meet the 18-inch requirement.

[0042] As can be seen from the above, the epoxy resin composition and prepreg provided by the present invention can achieve a balance between flame retardant properties and impact resistance, and meet the requirements of BMS8-2 Class 3 Grade A TYPE 45.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A toughened modified flame-retardant epoxy resin composition, characterized in that, By weight of raw materials, it includes: Toughened modified flame-retardant epoxy resin A, 80-120 parts; Additives, 0-5 parts; Flame retardant, 10-40 parts; Pigment: 3-15 parts; Latent curing agent, 1-10 parts; Accelerator, 1-6 parts; The toughened modified flame-retardant epoxy resin A comprises: Flame-retardant epoxy resin, 50-90 parts; Epoxy thinner, 5-20 parts; Toughening agent, 10-25 parts; Catalyst, 0.01-0.5 parts; It also includes a chain extender, wherein the chain extender comprises at least one of a monoamine and a polyamine; the monoamine is either a primary amino group or a secondary amino group; the polyamine comprises at least one primary amino group and / or one secondary amino group; and the molar ratio of the total amount of the primary amino group and / or secondary amino group in the chain extender to the number of epoxy groups in the toughened and modified flame-retardant epoxy resin A is less than 0.

3.

2. The toughened modified flame-retardant epoxy resin composition according to claim 1, characterized in that: The flame-retardant epoxy resin is selected from one or more of phosphorus-containing epoxy resin, phosphorus-nitrogen epoxy resin, phosphorus-containing phenolic epoxy resin, and phosphorus-nitrogen phenolic epoxy resin.

3. The toughened modified flame-retardant epoxy resin composition according to claim 1, characterized in that: The epoxy diluent is a monofunctional or difunctional epoxy reactive diluent with a linear molecular structure and contains any one or more groups selected from ether, ester, and hydroxyl groups.

4. The toughened modified flame-retardant epoxy resin composition according to claim 1, characterized in that: The toughening agent is nitrile rubber, and the acrylonitrile content in the nitrile rubber is 15% to 40%; the catalyst is an organophosphorus compound.

5. The toughened modified flame-retardant epoxy resin composition according to claim 1, characterized in that: The flame retardant is selected from one or more of phosphorus-nitrogen type flame retardants, aluminum diethylphosphinate, hexaphenoxycyclotriphosphazene, melamine cyanate, and ammonium polyphosphate, and its powder particle size is ≤3μm.

6. The toughened modified flame-retardant epoxy resin composition according to claim 1, characterized in that: The pigment has a Mohs hardness of ≤3.5 and a powder particle size of ≤3μm.

7. The toughened modified flame-retardant epoxy resin composition according to claim 1, characterized in that: The latent curing agent is selected from at least one of aromatic amines, dicyandiamide, organic hydrazides, modified aromatic amines, modified dicyandiamide, modified organic hydrazides, and linear phenolic resins; the accelerator is selected from at least one of organic urea, modified organic urea, imidazole, and modified imidazole.

8. A method for preparing a toughened modified flame-retardant epoxy resin composition according to any one of claims 1 to 7, characterized in that, Includes the following steps: S11. According to the weight of raw materials, add 50-90 parts of flame-retardant epoxy resin, 10-25 parts of toughening agent, and 5-20 parts of epoxy diluent to the reactor. Under nitrogen protection, add 0.01-0.5 parts of catalyst, heat to 120-170℃ and stir for 1-4 hours to obtain toughened modified flame-retardant epoxy resin A. S12. Cool the toughened modified flame-retardant epoxy resin A to 80-130℃, add 0-5 parts of additives, 10-40 parts of flame retardant, and 3-15 parts of pigment according to the weight of the raw materials, mix evenly, then add chain extender and react for 30-120 minutes to obtain toughened modified flame-retardant epoxy resin B; the chain extender includes at least one of monoamines and polyamines; the monoamine is either a primary amino group or a secondary amino group; the polyamine includes at least one primary amino group and / or one secondary amino group; the molar ratio of the total amount of primary amino groups and / or secondary amino groups in the chain extender to the epoxy groups in the toughened modified flame-retardant epoxy resin A is less than 0.3; S13. Cool the toughened and modified flame-retardant epoxy resin B to 60-90℃, add 1-10 parts of latent curing agent and 1-6 parts of accelerator, mix and stir for 15-60 minutes to obtain the toughened and modified flame-retardant epoxy resin composition.

9. A prepreg for aircraft cargo hold bulkheads, characterized in that: A film is made from the toughened modified flame-retardant epoxy resin composition according to any one of claims 1 to 8, and is impregnated with a fiber reinforcement, wherein the content of the resin composition is 36±3%.

10. An aircraft cargo hold bulkhead, characterized in that, It is prepared using the prepreg described in claim 9.

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