Reactive dye interface modification-based flame-retardant epoxy resin composite material and preparation method thereof

Abstract

The invention discloses a flame-retardant epoxy resin composite material based on reactive dye interface modification and a preparation method thereof.The flame-retardant epoxy resin composite material is prepared by filling 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide into mesoporous silica channels through the design thought of channel confinement loading-surface reactive blocking, and then conducting surface reactive blocking on the surfaces of the mesoporous silica channels to obtain the flame-retardant epoxy resin composite material based on reactive dye interface modification. A multi-active-group reactive dye is used for surface functional modification, integrated flame-retardant pigment particles with flame-retardant, coloring and reactive functions are constructed, and synergistic improvement of flame-retardant performance, coloring stability and dispersing performance is achieved.

Description

Technical Field

[0001] This application belongs to the field of polymer composite materials technology, specifically relating to a flame-retardant epoxy resin composite material based on reactive dye interface modification and its preparation method. Background Technology

[0002] Epoxy resins hold a core position in coatings, electronic packaging, and aerospace composite materials due to their excellent mechanical properties, strong adhesion, chemical corrosion resistance, and electrical insulation. However, their inherent flammability and the problem of releasing large amounts of smoke and producing molten droplets during combustion severely limit their application in high-end fields with high flame retardancy requirements. To overcome this deficiency, existing technologies often modify epoxy resins by adding flame retardants. Among them, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives are considered highly efficient flame retardant modifiers for epoxy resins because they can exert both gas-phase and condensed-phase flame retardant mechanisms due to their high phosphorus content and excellent thermal stability. However, as a small-molecule flame retardant, DOPO is prone to migration and volatilization when directly added to the epoxy resin matrix, and its compatibility with the matrix is ​​limited, making it difficult to guarantee the long-term flame retardant effect and stability of the material. To address the problem of easy migration of small-molecule flame retardants, researchers have introduced porous materials for loading. Mesoporous silica, with its high specific surface area, good thermal stability, and regular pore structure, is an ideal carrier. Liquid flame retardants or phase change flame retardants can be effectively loaded using vacuum-assisted impregnation. While some research has attempted to introduce flame retardant-loaded mesoporous silica into epoxy resins, this method often leads to nanoparticle agglomeration and uneven dispersion in the matrix, resulting in stress concentration and a significant decrease in the mechanical properties of the composite material. Meanwhile, with increasing market demands for diverse coating colors, the limited color options of epoxy resin coatings are becoming increasingly apparent. Although reactive dyes offer vibrant colors, their application in flame retardant systems often faces challenges such as interactions between dyes and flame retardants affecting stability, and the increased complexity and cost of multi-component systems. Multi-functional reactive dyes can be combined with mesoporous silica using silane coupling agents and simultaneously added to the epoxy resin prepolymer for co-curing. The remaining reactive groups after the reaction can undergo cross-linking reactions with the curing agent or epoxy resin, and the resulting covalent bonds can significantly improve the uniformity of particle dispersion in the epoxy resin. However, current research focuses on the synthesis of single flame-retardant particles without fully considering multifunctional integration and the simplification of the synthesis process. At the same time, the synthesized particles do not have reactive groups and fail to combine with epoxy resin. They are prone to particle aggregation due to van der Waals forces, which in turn damages the mechanical properties of epoxy resin. Some studies use liquid flame retardants with room temperature stirring and loading, which is not only inefficient, but also more prone to leakage than phase change flame retardants.

[0003] Taking existing patents as examples, CN103788408A discloses a DOPO-modified inorganic flame retardant and its preparation method. This invention uses a silicon-oxygen coupling agent as a "bridge" to combine DOPO with silicon dioxide. Although the flame-retardant material prepared by this invention has good flame-retardant and mechanical properties when applied to glass fiber, its synthesis process is cumbersome and the heat treatment time is too long, resulting in a lack of integrated color and flame retardancy and economic benefits. At the same time, the particles themselves do not have groups that react with epoxy resin, which easily leads to particle agglomeration during the epoxy resin curing process, thus affecting the dispersion performance. CN120441988A discloses a flame-retardant modified ABS plastic and its preparation method. The synthesized metal-organic framework ZIF-67 has a complete pore structure. The flame-retardant material is synthesized by continuously stirring the flame retardant dimethyl methylphosphonate at room temperature for 48 hours and changing the impregnation solution multiple times. However, its synthesis time is relatively long, and dimethyl methylphosphonate, as a liquid flame retardant, is loaded in the pores. Compared with phase change flame retardants, it has a higher risk of precipitation and is prone to leakage during use, causing environmental pollution. Summary of the Invention

[0004] This application provides a flame-retardant epoxy resin composite material based on reactive dye interface modification and its preparation method, in order to solve the technical problems in the prior art, such as the difficulty in achieving a single color of epoxy resin coating and flame-retardant function in synergy, the poor long-term flame-retardant effect caused by the easy migration and volatilization of small molecule flame retardants, the mechanical property degradation caused by uneven dispersion of supported flame retardants in the matrix, and the low loading efficiency of liquid flame retardants at room temperature and the easy leakage during use causing environmental pollution.

[0005] To solve the above-mentioned technical problems, one technical solution adopted in this application is: a method for preparing a flame-retardant epoxy resin composite material based on reactive dye interface modification, comprising:

[0006] S1. Disperse hexadecyltrimethylammonium bromide in deionized water, add sodium hydroxide solution to adjust the pH value, stir at 60-90℃ for 30 min, add tetraethyl orthosilicate dropwise, react for 1-6 h, centrifuge, wash, freeze dry to obtain hexadecyltrimethylammonium bromide@mesoporous silica;

[0007] S2. The hexadecyltrimethylammonium bromide@mesoporous silica is dispersed in a mixed solution of ethanol and hydrochloric acid, and the hexadecyltrimethylammonium bromide is removed by solvent extraction 2 to 3 times at 60 to 80°C. Then, the silica is obtained by centrifugation, washing and freeze drying.

[0008] S3. The mesoporous silica is mixed with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and stirred for 1 to 3 hours at 60 to 90°C and 60 to 100 kPa. The mixture is then heated to 120 to 150°C and reacted for 1 to 3 hours. After washing with ethanol and water, centrifuging, and freeze-drying, flame-retardant mesoporous silica is obtained.

[0009] S4. The flame-retardant mesoporous silica is dispersed in a mixed solution of ethanol and water, and a silane coupling agent is added at 30-70°C. After reacting for 1-3 hours, the silica is centrifuged, washed, and freeze-dried to obtain modified flame-retardant mesoporous silica.

[0010] S5. The modified flame-retardant mesoporous silica is dispersed in ethanol, and an aqueous solution of reactive dye is added at 30-90°C. After reacting for 1-3 hours, the mixture is centrifuged, washed, and freeze-dried to obtain flame-retardant colored mesoporous silica.

[0011] S6. Take a mixture of epoxy resin and curing agent and prepolymerize it at 60-90°C for 10-30 min, add the flame-retardant colored mesoporous silica, and continue to react at 60-90°C for 10-30 min to obtain flame-retardant colored mesoporous silica@epoxy resin prepolymer.

[0012] S7. The flame-retardant colored mesoporous silica@epoxy resin prepolymer is poured into a mold and cured in an oven to obtain the flame-retardant epoxy resin composite material.

[0013] Further, in step S1, the ratio of the amount of hexadecyltrimethylammonium bromide: sodium hydroxide: tetraethyl orthosilicate: deionized water is (0.3-0.6) g: (0.1-0.3) g: (3-6) mL: 480 mL.

[0014] Furthermore, in step S2, the ratio of hexadecyltrimethylammonium bromide@mesoporous silica: ethanol: hydrochloric acid is (0.5-1) g: 48 mL: (1-3) mL; and the solvent extraction time is 8-16 h.

[0015] Furthermore, in step S3, the mass ratio of the mesoporous silica to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1 to 3.

[0016] Further, in step S4, the silane coupling agent is KH560 or KH550; the ratio of the amount of the flame-retardant mesoporous silica: silane coupling agent: ethanol and water mixture is (1-5) g: (0.5-1) mL: 50 mL; the volume ratio of ethanol to water in the ethanol and water mixture is (1-30): 1.

[0017] Further, in step S5, the reactive dye is a dual reactive group reactive dye, including Reactive Yellow 145, Reactive Red 195 or Reactive Blue 194; the concentration of the reactive dye aqueous solution is 150 g / L; the ratio of the amount of modified flame-retardant mesoporous silica: ethanol: reactive dye aqueous solution is (1-5) g: 50 mL: (1-5) mL.

[0018] Further, in step S6, the epoxy resin is an E44 or E51 type epoxy resin; the curing agent is an amine curing agent; and the ratio of flame-retardant colored mesoporous silica: epoxy resin: curing agent is (0.5-5) g: 85 g: (5-15) g.

[0019] Furthermore, in step S7, the curing conditions are curing at 80–140°C for 1–4 hours.

[0020] One technical solution adopted in this application is: a flame-retardant epoxy resin composite material prepared by the above-mentioned preparation method, comprising an epoxy resin matrix, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, a silane coupling agent, a reactive dye, a curing agent, and flame-retardant colored mesoporous silica; by weight percentage, epoxy resin accounts for 81.0% to 93.9%, curing agent accounts for 5.3% to 14.9%, mesoporous silica accounts for 0.1% to 1.2%, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide accounts for 0.2% to 2.5%, silane coupling agent accounts for 0.1% to 1.05%, and reactive dye accounts for 0.05% to 0.7%.

[0021] The beneficial effects of this application are:

[0022] This application adopts the design concept of "pore confinement loading-surface reactive blocking" to fill the pores of mesoporous silica with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and uses multi-active group reactive dyes for surface functionalization modification to construct integrated flame retardant pigment particles with flame retardant, coloring and reactive functions, thereby achieving a synergistic improvement in flame retardant performance, coloring stability and dispersion performance.

[0023] This application employs vacuum-assisted melt filling technology, which utilizes capillary effect and vacuum environment to promote the entry of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide melt into mesoporous silica channels. Compared with conventional room temperature stirring impregnation method, the loading efficiency is significantly improved. Furthermore, after the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide crystallizes in a confined manner within the channels, its migration and volatilization behaviors are effectively suppressed, ensuring long-term flame retardant stability.

[0024] This application uses a silane coupling agent to covalently graft multi-reactive group reactive dyes onto the particle surface, which not only gives the particles a bright color, but also improves the dispersion stability of the particles in the epoxy resin prepolymer through electrostatic repulsion of the sulfonic acid groups. The remaining reactive groups of the dye molecules (such as vinyl sulfone group and monochlorotriazine group) can undergo cross-linking reaction with epoxy groups or amine curing agents during the curing process to form a covalent interface layer, which alleviates the problems of interface debonding and stress concentration caused by the introduction of nanoparticles.

[0025] The reactive dyes are firmly anchored to the particle surface and participate in curing and cross-linking, which effectively inhibits the migration and precipitation of dyes in the matrix and improves the coloring uniformity. At the same time, the preparation process is relatively simple and does not require complex processes, providing a feasible path for the functional integration of epoxy resin composites. Attached Figure Description

[0026] Figure 1 This is a SEM image of the mesoporous silica synthesized in Example 1 of this application; wherein, Figure 1 The synthesized mesoporous silica is shown to be uniformly spherical;

[0027] Figure 2 This is a SEM image of the flame-retardant mesoporous silica synthesized in Example 1 of this application; wherein, Figure 2 The mesoporous silica remained spherical after being melt-blended with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and no large blocks of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were observed. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0029] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification.

[0030] Example 1: Preparation of flame-retardant epoxy resin composite material - 1

[0031] (1) Disperse 0.5g of hexadecyltrimethylammonium bromide in 480mL of deionized water, add 1.75mL of 2mol / L sodium hydroxide solution to adjust the pH value, stir at 80℃ for 30min, add tetraethyl orthosilicate dropwise using a constant flow pump, and after reacting for 2h, centrifuge, wash and freeze dry to obtain hexadecyltrimethylammonium bromide@mesoporous silica;

[0032] (2) 1 g of hexadecyltrimethylammonium bromide@mesoporous silica was dispersed in 50 mL of a mixed solution of ethanol and hydrochloric acid (48 mL of ethanol + 2 mL of hydrochloric acid). The hexadecyltrimethylammonium bromide was removed by solvent extraction twice (12 h each time) at 60 °C. After multiple centrifugations, washing and freeze drying, mesoporous silica was obtained.

[0033] (3) Mix 1g of mesoporous silica with 2g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, stir for 2h at 80℃ and 80kPa, heat to 140℃ and react for 1h, wash with ethanol and water multiple times, centrifuge and freeze dry to obtain flame-retardant mesoporous silica.

[0034] (4) 3g of flame-retardant mesoporous silica was dispersed in a 50mL mixture of ethanol and water (48mL ethanol + 2mL water), and 1g of silane coupling agent KH550 was added at 70℃. After reacting for 2h, the mixture was centrifuged, washed, and freeze-dried to obtain modified flame-retardant mesoporous silica.

[0035] (5) 3g of modified flame-retardant mesoporous silica was dispersed in 50mL of ethanol, and 5mL of 150g / L active yellow 145 aqueous solution was added at 80℃. After reacting for 2h, the mixture was centrifuged, washed, and freeze-dried to obtain flame-retardant colored mesoporous silica.

[0036] (6) Take 85g of epoxy resin e44 and 12g of isophorone diamine curing agent mixture, prepolymerize at 70℃ for 15min, add 3g of flame retardant colored mesoporous silica, and continue to react at 70℃ for 15min to obtain flame retardant colored mesoporous silica@epoxy resin prepolymer.

[0037] (7) 100g of flame-retardant colored mesoporous silica@epoxy resin prepolymer was poured into a mold and placed in an oven at 120℃ for 2h to obtain flame-retardant epoxy resin composite material-1.

[0038] Example 2: Preparation of flame-retardant epoxy resin composite material - 2

[0039] The amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in step (3) of Example 1 was changed to 1g, and the remaining steps were the same as in Example 1, to obtain flame-retardant epoxy resin composite material-2.

[0040] Example 3: Preparation of flame-retardant epoxy resin composite material - 3

[0041] The amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in step (3) of Example 1 was changed to 3g, and the remaining steps were the same as in Example 1, to obtain flame-retardant epoxy resin composite material-3.

[0042] Example 4: Preparation of Flame-Retardant Epoxy Resin Composite Material - 4

[0043] The amount of active yellow 145 aqueous solution in step (5) of Example 1 was changed to 1 mL, and the remaining steps were the same as in Example 1, to obtain flame retardant epoxy resin composite material-4.

[0044] Example 5: Preparation of flame-retardant epoxy resin composite material - 5

[0045] The amount of flame-retardant colored mesoporous silica in step (6) of Example 1 was changed to 1g, and the remaining steps were the same as in Example 1, to obtain flame-retardant epoxy resin composite material-5.

[0046] Comparative Example 1: Preparation of ordinary epoxy resin

[0047] Delete steps (1)-(5) in Example 1, directly take 85g of epoxy resin e44 and 12g of isophorone diamine curing agent mixture, prepolymerize at 70℃ for 30min, pour the prepolymer into the mold, and cure at 120℃ for 2h to obtain ordinary epoxy resin.

[0048] Comparative Example 2: Preparation of mesoporous silica@epoxy resin

[0049] Steps (3)-(5) in Example 1 are deleted. In step (6), 3g of mesoporous silica is added to replace the flame-retardant colored mesoporous silica. The remaining steps are the same as in Example 1 to obtain mesoporous silica@epoxy resin.

[0050] Comparative Example 3: Preparation of Flame-Retardant Mesoporous Silica@Epoxy Resin

[0051] Steps (4)-(5) in Example 1 are deleted. In step (6), 3g of flame-retardant mesoporous silica is added to replace the flame-retardant colored mesoporous silica. The remaining steps are the same as in Example 1 to obtain flame-retardant mesoporous silica@epoxy resin.

[0052] Comparative Example 4: Preparation of Physically Mixed Flame-Retardant Epoxy Resin

[0053] Steps (3)-(5) in Example 1 were deleted. In step (6), 1g of mesoporous silica and 2g of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide were added to replace the flame-retardant colored mesoporous silica. The remaining steps were the same as in Example 1, and a physically mixed flame-retardant epoxy resin was obtained.

[0054] Comparative Example 5: Preparation of Physically Mixed Colored Flame-Retardant Epoxy Resin

[0055] Steps (4)-(5) in Example 1 were deleted. In step (6), 3g of flame-retardant mesoporous silica and 5mL of 150g / L active yellow 145 aqueous solution were added to replace the flame-retardant colored mesoporous silica. The remaining steps were the same as in Example 1, and a physically mixed colored flame-retardant epoxy resin was obtained.

[0056] Performance testing

[0057] Performance tests were conducted on the products of the above embodiments and comparative examples, and the test methods are as follows:

[0058] 1. SEM characterization: The sample was diluted with ethanol and dropped onto the surface of a silicon wafer, dried at room temperature, sputtered with gold, and then its microstructure was observed by field emission scanning electron microscopy.

[0059] 2. Limiting Oxygen Index (LOI) Test: Performed according to ASTM D 2863 standard;

[0060] 3. Mechanical property testing: According to GB / T1040-2006 Standard for Tensile Properties of Plastics, flexural modulus, flexural strength, tensile strength and elongation at break are tested;

[0061] 4. Color performance test: The K / S value was measured using a colorimeter under D65 light source and 10° viewing angle conditions;

[0062] 5. Carbon residue test: determined by thermogravimetric analysis.

[0063] Test Results and Analysis

[0064] Table 1 shows the performance tests of epoxy resin composite materials.

[0065]

[0066] As shown in Table 1, the flame-retardant epoxy resin composite materials prepared in this invention (Examples 1-5) exhibit excellent comprehensive properties:

[0067] Color performance: The K / S values ​​of Examples 1-5 are significantly higher than those of Comparative Examples 1-4, indicating that the interface modification of the reactive dye achieves a good coloring effect. Among them, the K / S value of Example 2 reaches 6.46, with bright color.

[0068] Flame retardant performance: The LOI values ​​of Examples 1-5 were all above 37%, which was much higher than that of Comparative Example 1 (25.5%) and Comparative Example 2 (27.1%). The LOI value of Example 3 reached 42.7%, and the char residue was 24.2%, showing excellent flame retardant effect. This is due to the pore-confined loading of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, which effectively inhibited its migration and volatilization.

[0069] Mechanical properties: The flexural strength and tensile strength of Examples 1-5 are better than those of Comparative Examples 2-5. The flexural strength of Example 1 reaches 78.5 MPa and the tensile strength is 66.2 MPa, indicating that the covalent interface layer formed by the reactive dye modification effectively alleviates the stress concentration problem caused by particle aggregation and improves the interface compatibility.

[0070] Stability: The elongation at break of the products in the examples remained between 3.4% and 4.7%, which was more stable than that of the physically blended Comparative Example 4 (1.9%) and Comparative Example 5 (2.8%), demonstrating that chemical bonding enhanced the structural stability of the materials.

[0071] In Example 2, reducing the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide slightly decreased the flame retardant performance, but the mechanical properties remained stable. In Example 3, increasing the amount of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide improved the flame retardant performance, but the excessive flame retardant occupied the reaction sites in the pores, leading to a decrease in dye binding and a slight reduction in mechanical properties. In Example 4, reducing the amount of reactive dye significantly decreased the K / S value, while the other properties were less affected. In Example 5, reducing the amount of flame-retardant colored mesoporous silica both decreased the K / S value and the LOI value, which is consistent with the positive correlation between dosage and performance.

[0072] Comparative Example 1 (ordinary epoxy resin) had the worst flame retardant performance; Comparative Example 2 (mesoporous silica@epoxy resin) had poor flame retardant effect due to the absence of flame retardant, and uneven particle dispersion resulted in poor mechanical properties; Comparative Example 3 (flame retardant mesoporous silica@epoxy resin) had a certain flame retardant effect, but lacked reactive dye modification, resulting in poor coloring performance and poor mechanical properties.

[0073] Comparative Example 4 (physically mixed flame-retardant epoxy resin) and Comparative Example 5 (physically mixed colored flame-retardant epoxy resin) have significantly inferior mechanical properties and stability compared to the embodiments of the present invention because they did not form chemical bonds and the particles were severely agglomerated.

[0074] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for preparing a flame-retardant epoxy resin composite material based on reactive dye interface modification, characterized in that, include: S1. Disperse hexadecyltrimethylammonium bromide in deionized water, add sodium hydroxide solution to adjust the pH value, stir at 60-90℃ for 30 min, add tetraethyl orthosilicate dropwise, react for 1-6 h, centrifuge, wash, freeze dry to obtain hexadecyltrimethylammonium bromide@mesoporous silica; S2. The hexadecyltrimethylammonium bromide@mesoporous silica is dispersed in a mixed solution of ethanol and hydrochloric acid, and the hexadecyltrimethylammonium bromide is removed by solvent extraction 2 to 3 times at 60 to 80°C. Then, the silica is obtained by centrifugation, washing and freeze drying. S3. The mesoporous silica is mixed with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and stirred for 1 to 3 hours at 60 to 90°C and 60 to 100 kPa. The mixture is then heated to 120 to 150°C and reacted for 1 to 3 hours. After washing with ethanol and water, centrifuging, and freeze-drying, flame-retardant mesoporous silica is obtained. S4. The flame-retardant mesoporous silica is dispersed in a mixed solution of ethanol and water, and a silane coupling agent is added at 30-70°C. After reacting for 1-3 hours, the silica is centrifuged, washed, and freeze-dried to obtain modified flame-retardant mesoporous silica. S5. The modified flame-retardant mesoporous silica is dispersed in ethanol, and an aqueous solution of reactive dye is added at 30-90°C. After reacting for 1-3 hours, the mixture is centrifuged, washed, and freeze-dried to obtain flame-retardant colored mesoporous silica. S6. Take a mixture of epoxy resin and curing agent and prepolymerize it at 60-90°C for 10-30 min, add the flame-retardant colored mesoporous silica, and continue to react at 60-90°C for 10-30 min to obtain flame-retardant colored mesoporous silica@epoxy resin prepolymer. S7. The flame-retardant colored mesoporous silica@epoxy resin prepolymer is poured into a mold and cured in an oven to obtain the flame-retardant epoxy resin composite material.

2. The method according to claim 1, characterized in that, In step S1, the ratio of hexadecyltrimethylammonium bromide, sodium hydroxide, tetraethyl orthosilicate, and deionized water is (0.3-0.6) g: (0.1-0.3) g: (3-6) mL: 480 mL.

3. The method according to claim 1, characterized in that, In step S2, the ratio of hexadecyltrimethylammonium bromide@mesoporous silica: ethanol: hydrochloric acid is (0.5-1) g: 48 mL: (1-3) mL; the solvent extraction time is 8-16 h.

4. The method according to claim 1, characterized in that, In step S3, the mass ratio of the mesoporous silica to 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 1:1 to 3.

5. The method according to claim 1, characterized in that, In step S4, the silane coupling agent is KH560 or KH550; the ratio of the amount of the flame-retardant mesoporous silica: silane coupling agent: ethanol and water mixture is (1-5) g: (0.5-1) mL: 50 mL; the volume ratio of ethanol to water in the ethanol and water mixture is (1-30):

1.

6. The method according to claim 1, characterized in that, In step S5, the reactive dye is a dual reactive group reactive dye, including Reactive Yellow 145, Reactive Red 195 or Reactive Blue 194; the concentration of the reactive dye aqueous solution is 150 g / L; the ratio of modified flame-retardant mesoporous silica: ethanol: reactive dye aqueous solution is (1-5) g: 50 mL: (1-5) mL.

7. The method according to claim 1, characterized in that, In step S6, the epoxy resin is an E44 or E51 type epoxy resin; the curing agent is an amine curing agent; and the ratio of flame-retardant colored mesoporous silica: epoxy resin: curing agent is (0.5-5) g: 85 g: (5-15) g.

8. The method according to claim 1, characterized in that, In step S7, the curing conditions are curing at 80–140°C for 1–4 hours.

9. A composite material prepared by the preparation method according to any one of claims 1-8, characterized in that, The product comprises an epoxy resin matrix, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, a silane coupling agent, a reactive dye, a curing agent, and flame-retardant colored mesoporous silica; by weight percentage, the epoxy resin accounts for 81.0% to 93.9%, the curing agent accounts for 5.3% to 14.9%, the mesoporous silica accounts for 0.1% to 1.2%, the 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide accounts for 0.2% to 2.5%, the silane coupling agent accounts for 0.1% to 1.05%, and the reactive dye accounts for 0.05% to 0.7%.

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