Continuous fiber reinforced material and preparation method thereof

Abstract

The invention relates to the technical field of fiber reinforced materials, and discloses a continuous fiber reinforced material and a preparation method thereof, and the method comprises the following steps: preparing a smoke suppressant compound composition, and carrying out surface hydrophobic modification treatment on metal hydroxide; preparing phase-change heat-absorbing material microcapsules, and adding hydrophobic inorganic nanoparticles into a shell material to enhance the compactness; preparing a catalytic char-forming synergist composition, and carrying out anti-hydrolysis stabilizer end-capping treatment on the organic phosphorus compound; the components and the moisture absorption regulating agent are jointly dispersed in the matrix resin to form the flame-retardant matrix resin composition; and compounding the continuous fibers and the flame-retardant matrix resin composition, and carrying out curing molding. The comprehensive fireproof safety is improved by 4-6 times compared with that of a traditional flame-retardant material through triple synergistic effects of smoke suppression, heat absorption and charring, and meanwhile, the initial flame-retardant performance of the material can still be kept at 85% or above in a high-humidity and high-temperature environment for 6-12 months through multiple damp-heat-aging-resistant improvement measures.

Description

Technical Field

[0001] This invention relates to the field of fiber-reinforced materials technology, and more specifically, to a continuous fiber-reinforced material and its preparation method. Background Technology

[0002] Continuous fiber reinforced composites are widely used in fields with high material performance requirements, such as aerospace, civil engineering, transportation, and marine engineering, due to their excellent mechanical properties, including high specific strength and high specific modulus. However, traditional continuous fiber reinforced composites generally have flammability issues, easily burning rapidly and releasing large amounts of toxic fumes under fire conditions, posing a serious threat to personnel and property safety.

[0003] While existing flame-retardant composite materials improve their flame retardancy rating by adding flame retardants to the matrix, significant technical drawbacks remain: First, the smoke produced during combustion is highly concentrated and toxic, hindering personnel evacuation and firefighting efforts; second, the rapid accumulation of heat during combustion accelerates the spread of fire; and third, the char layer forms slowly and is not dense enough to effectively isolate oxygen and heat transfer. More seriously, existing flame-retardant composite materials face severe performance degradation issues under long-term use in high-humidity and high-temperature environments: metal hydroxide smoke suppressants agglomerate and fail due to moisture absorption; the microcapsule shells of phase change endothermic materials crack during humid and hot cycles, leading to core leakage; organophosphorus charring agents undergo hydrolysis under humid conditions, losing their catalytic activity; and there is also competitive adsorption of moisture among various flame-retardant components, further disrupting the synergistic effect. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a continuous fiber reinforced material and its preparation method.

[0005] A method for preparing a continuous fiber reinforced material includes the following steps: Step 1: Preparation of smoke suppressant compound composition: After compounding metal hydroxide with a molybdenum-boron composite catalyst, the surface of the metal hydroxide is modified by hydrophobic treatment using a silane coupling agent or fatty acid to obtain a surface-hydrophobic modified smoke suppressant compound composition. Step 2: Preparation of phase change endothermic material microcapsules: Microcapsules of phase change endothermic materials were prepared by in-situ polymerization using organic phase change materials or inorganic salt phase change materials as the core material and organic-inorganic hybrid materials containing hydrophobic inorganic nanoparticles, composed of urea-formaldehyde resin prepolymer and inorganic fillers, as the shell material. Step 3: Preparation of catalytic char formation synergist composition: After the organophosphorus compound and the epoxy group end-capping agent are subjected to anti-hydrolysis stabilization treatment, they are compounded with a catalytic synergist to obtain a catalytic char formation synergist composition; Step 4: Preparation of flame-retardant matrix resin composition: Molecular sieve microspheres are added to the matrix resin as a moisture-absorbing regulator, and the components prepared in steps 1-3 are dispersed in the matrix resin to obtain a flame-retardant matrix resin composition. Step 5: Preparation of continuous fiber-reinforced materials: A continuous fiber reinforced material is obtained by combining a continuous fiber with a flame-retardant matrix resin composition and then curing it.

[0006] Preferably, the metal hydroxide comprises aluminum hydroxide and magnesium hydroxide, mixed in a mass ratio of 2:1 to 1:2; the molybdenum-boron composite catalyst is prepared by mixing ammonium molybdate and boric acid in a mass ratio of 1:0.5 to 1:2; and the metal hydroxide mixture is compounded with the molybdenum-boron composite catalyst in a mass ratio of 10:1 to 5:1.

[0007] Preferably, the surface hydrophobic modification treatment involves heating the smoke suppressant compound composition at 80-120°C, adding 2-5% by mass of a silane coupling agent or fatty acid of the total metal hydroxide content, and reacting at a rotation speed of 300-800 r / min for 60-120 min, so that the modifier forms a hydrophobic molecular layer on the surface of the metal hydroxide.

[0008] Preferably, the organic phase change material is selected from one or more of n-eicosane, n-docosahexanes, palmitic acid, stearic acid, and polyethylene glycol, with a phase change temperature of 50-90℃; the inorganic salt phase change material is selected from sodium acetate trihydrate or potassium nitrate-sodium nitrate eutectic system, with a phase change temperature of 120-180℃.

[0009] Preferably, the hydrophobic inorganic nanoparticles are selected from one or more of hydrophobic nano-silica, hydrophobic nano-alumina, and hydrophobic nano-zinc oxide, and the amount added is 5-15% of the total amount of shell material, with a particle size of 10-50 nanometers.

[0010] Preferably, the in-situ polymerization method involves mixing an organic phase change material with a hybrid shell precursor solution composed of urea-formaldehyde resin prepolymer and inorganic filler at a core-shell mass ratio of 1:0.3-1:1, and allowing the urea-formaldehyde resin prepolymer to undergo polycondensation reaction for 2-4 hours at a temperature of 60-80℃ and a pH of 6.0-8.0 under the action of an emulsifier concentration of 0.5-2.0 wt%, to obtain microcapsules with a particle size of 5-50 micrometers and an encapsulation rate greater than 85%.

[0011] Preferably, the organophosphorus compound is selected from one or more of triphenyl phosphate, tricresyl phosphate, and ammonium polyphosphate; the epoxy end-capping agent is selected from epichlorohydrin or bisphenol A diglycidyl ether; the hydrolysis stabilization treatment is to mix the organophosphorus compound and the epoxy end-capping agent in a molar ratio of 1:0.1-1:0.5 and react them at 60-100°C for 2-4 hours in the presence of an alkaline catalyst.

[0012] Preferably, the catalytic synergist is selected from one or more transition metal compounds among iron oxide, zinc oxide, and nickel oxide, or from one or more organometallic compounds among tetrabutyl titanate and tetraisopropyl titanate; the hydrolysis-resistant and stabilized organophosphorus compound is mixed with the catalytic synergist in a mass ratio of 5:1 to 10:1.

[0013] Preferably, the molecular sieve microspheres are selected from type A or type X molecular sieves with a pore size of 3-5 angstroms and a particle size of 1-10 micrometers, and the addition amount is 1-5% of the mass of the matrix resin; the smoke suppressant compound composition, the phase change heat endothermic material microcapsule, and the catalytic char formation synergist composition are added to the matrix resin in proportions of 10-25%, 5-15%, and 8-20% of the mass of the matrix resin, respectively.

[0014] Preferably, the continuous fiber is selected from one or more of carbon fiber, glass fiber, aramid fiber, and basalt fiber; after pretreatment, the continuous fiber is impregnated and compounded with a flame-retardant matrix resin composition for 30-60 minutes, and then cured at 120-180℃ and 0.2-1.0MPa for 2-4 hours.

[0015] The beneficial effects of this invention are as follows: Significantly enhanced synergistic flame retardant effect: Through the synergistic effect of the smoke suppressant compound composition, phase change heat-absorbing material microcapsules, and catalytic char-forming synergist composition, a three-dimensional protection system of "rapid char formation to isolate oxygen - phase change heat absorption and cooling - continuous smoke suppression and toxicity reduction" is formed. Metal hydroxides decompose at 300-450℃, releasing water vapor (aluminum hydroxide's initial decomposition temperature is approximately 200℃, and its complete decomposition temperature is approximately 300-350℃; magnesium hydroxide's initial decomposition temperature is approximately 340℃, and its complete decomposition temperature is approximately 430-450℃. Furthermore, their decomposition is an endothermic process, and the flame-retardant alumina and magnesium oxide products can deposit on the surface of combustibles, isolating air and thus achieving flame retardancy), diluting the concentration of combustible gases; molybdenum-boron compounds catalyze the agglomeration of smoke particles at 400-500℃, reducing the smoke density level from Ds≥450 to Ds≤75; phase change materials, in the early stages of a fire, at 50℃... The latent heat is absorbed in stages within a temperature range of -180℃ (organic phase change materials such as n-eicosane absorb 246kJ / kg of latent heat of fusion at 50-90℃, and inorganic salt phase change materials such as sodium acetate trihydrate absorb 265kJ / kg of heat through phase change at 120-180℃), which reduces the temperature rise rate of the combustion zone by 40-60% and extends the effective action time of the smoke suppressant by 30-50%; the catalytic charring agent promotes the formation of a dense char layer at 250-300℃, with a char layer thickness of 2-5mm, and reduces the oxygen permeability to less than 1 / 10 of the original substrate. The three promote each other, increasing the oxygen index of the material from 22-24 to 32-35.

[0016] Excellent resistance to humid and hot environments: Through the comprehensive application of surface hydrophobic modification technology, shell reinforcement technology, hydrolysis stabilization treatment, and moisture regulation and balance technology, the performance degradation problem of traditional flame retardant materials in humid and hot environments is effectively solved. The hydrophobic modification layer blocks the diffusion of moisture to the hydroxide surface, the microcapsule shell reinforced with hydrophobic nanoparticles prevents cracking during humid and hot cycles, the epoxy end-capping treatment fundamentally blocks the hydrolysis reaction of organophosphorus compounds, and the selective adsorption of molecular sieve microspheres maintains the moisture balance of the multi-component system, ensuring the long-term stability of the material in high humidity and high temperature environments.

[0017] Comprehensive improvement in fire safety: Compared to traditional single flame-retardant methods, the multi-component synergistic flame-retardant system constructed in this implementation not only upgrades the material's flame-retardant rating from B1 to A, but more importantly, significantly reduces secondary fire hazards. A char layer forms within 3-5 minutes, effectively isolating oxygen and heat transfer; phase change endothermics reduce the flame surface temperature from 800-1000℃ to 600-700℃; smoke generation rate is reduced by 50-70%, and CO production is reduced by 40-60%, significantly improving the evacuation environment and firefighting conditions under fire circumstances.

[0018] The process is highly operable: the surface modification, microcapsule preparation, and compound dispersion technologies employed in this invention are innovative combinations of existing industrial technologies. The required equipment consists of standard, conventional equipment such as high-speed mixers, planetary mixers, and ball mills. The process temperature does not exceed 180℃, and the pressure is between atmospheric pressure and 0.5MPa, avoiding extreme process conditions. The process parameters for each step are within a moderate range, quality control points are clearly defined, and the production cycle is 8-12 hours, making it suitable for mass implementation on existing composite material production lines. Attached Figure Description

[0019] Figure 1 This is a bar chart comparing the oxygen index of the present invention; Figure 2 This is a bar chart comparing the smoke density levels of the present invention; Figure 3 This is a bar chart comparing the thickness of the char layer after combustion according to the present invention. Detailed Implementation

[0020] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples. Example

[0021] This embodiment proposes a method for preparing a continuous fiber reinforced material, including the following steps: Step 1: Preparation of smoke suppressant compound composition: After compounding metal hydroxide with a molybdenum-boron composite catalyst, the surface of the metal hydroxide was modified by a silane coupling agent to obtain a surface-hydrophobic smoke suppressant compound composition. Step 2: Preparation of phase change endothermic material microcapsules: Microcapsules of phase change endothermic materials were prepared by in-situ polymerization using organic phase change materials or inorganic salt phase change materials as the core material and organic-inorganic hybrid materials containing hydrophobic inorganic nanoparticles, composed of urea-formaldehyde resin prepolymer and inorganic fillers, as the shell material. Step 3: Preparation of catalytic char formation synergist composition: After the organophosphorus compound and the epoxy group end-capping agent are subjected to anti-hydrolysis stabilization treatment, they are compounded with a catalytic synergist to obtain a catalytic char formation synergist composition; Step 4: Preparation of flame-retardant matrix resin composition: Molecular sieve microspheres are added to the matrix resin as a moisture-absorbing regulator, and the components prepared in steps 1-3 are dispersed in the matrix resin to obtain a flame-retardant matrix resin composition. Step 5: Preparation of continuous fiber-reinforced materials: A continuous fiber reinforced material is obtained by combining a continuous fiber with a flame-retardant matrix resin composition and then curing it.

[0022] in: Metal hydroxides include aluminum hydroxide and magnesium hydroxide, mixed in a 1:1 mass ratio; The molybdenum-boron composite catalyst was prepared by mixing ammonium molybdate and boric acid in a mass ratio of 1:1.2. The metal hydroxide mixture and the molybdenum-boron composite catalyst were compounded at a mass ratio of 7:1.

[0023] The surface hydrophobic modification treatment involves heating the smoke suppressant compound at 100°C, adding 3.5% by mass of silane coupling agent of the total metal hydroxide, and reacting at 550 r / min for 90 min to form a hydrophobic molecular layer on the surface of the metal hydroxide.

[0024] The organic phase change material is selected from n-eicosane, with a phase change temperature of 70℃; The inorganic salt phase change material is selected from sodium acetate trihydrate, with a phase change temperature of 150℃.

[0025] The hydrophobic inorganic nanoparticles are selected from hydrophobic nano-silica, and the amount added is 10% of the total shell material, with a particle size of 30 nanometers.

[0026] The in-situ polymerization method involves mixing an organic phase change material with a hybrid shell precursor solution composed of urea-formaldehyde resin prepolymer and inorganic filler at a core-shell mass ratio of 1:0.7. Under the action of an emulsifier concentration of 1.3wt%, the urea-formaldehyde resin prepolymer undergoes a polycondensation reaction at a temperature of 70℃ and a pH of 7.0 for 3 hours to obtain microcapsules with a particle size of 30 micrometers and an encapsulation rate greater than 85%.

[0027] Organophosphorus compounds are selected from triphenyl phosphates; The epoxy group terminator is selected from epichlorohydrin; The hydrolysis stabilization treatment involves mixing an organophosphorus compound with an epoxy end-capping agent in a molar ratio of 1:0.3 and reacting the mixture at 80°C for 3 hours in the presence of an alkaline catalyst.

[0028] The catalytic synergist is selected from iron oxide transition metal compounds; The hydrolysis-resistant and stabilized organophosphorus compound and the catalytic synergist were mixed in a mass ratio of 8:1.

[0029] The molecular sieve microspheres were selected from type A molecular sieves with a pore size of 4 Å and a particle size of 6 μm, and the addition amount was 3% of the mass of the matrix resin. The smoke suppressant compound composition, the phase change heat endothermic material microcapsule, and the catalytic char formation synergist composition were added to the matrix resin in proportions of 18%, 10%, and 14% of the matrix resin mass, respectively.

[0030] Continuous fibers are selected from carbon fibers; After pretreatment, the continuous fibers were impregnated with a flame-retardant matrix resin composition for 45 minutes, and then cured at 150°C and 0.6 MPa for 3 hours. Example

[0031] The difference between this embodiment and Embodiment 1 is that: After compounding metal hydroxide with a molybdenum-boron composite catalyst, the surface of the metal hydroxide was modified with fatty acids to obtain a surface-hydrophobic smoke suppressant compound composition. Metal hydroxides include aluminum hydroxide and magnesium hydroxide, mixed in a mass ratio of 2:1; The molybdenum-boron composite catalyst was prepared by mixing ammonium molybdate and boric acid in a mass ratio of 1:0.5. The metal hydroxide mixture and the molybdenum-boron composite catalyst were compounded in a mass ratio of 10:1.

[0032] The surface hydrophobic modification treatment involves heating the smoke suppressant compound at 80°C, adding fatty acids at 2% of the total mass of the metal hydroxide, and reacting at 300 r / min for 60 min to form a hydrophobic molecular layer on the surface of the metal hydroxide.

[0033] The organic phase change material is selected from n-dodecane, and the phase change temperature is 50℃; The inorganic salt phase change material is selected from the potassium nitrate-sodium nitrate eutectic system, with a phase change temperature of 120℃.

[0034] The hydrophobic inorganic nanoparticles are selected from hydrophobic nano-alumina, with an addition amount of 5% of the total shell material and a particle size of 10 nanometers.

[0035] The in-situ polymerization method involves mixing a hybrid shell precursor solution composed of organic phase change material, urea-formaldehyde resin prepolymer, and inorganic filler at a core-shell mass ratio of 1:0.3. Under the action of an emulsifier concentration of 0.5wt%, the urea-formaldehyde resin prepolymer undergoes a polycondensation reaction at a temperature of 60℃ and a pH of 6.0 for 2 hours to obtain microcapsules with a particle size of 5 micrometers and an encapsulation rate greater than 85%.

[0036] The organophosphorus compound is selected from tricresyl phosphate; The epoxy group terminator is selected from bisphenol A diglycidyl ether; The hydrolysis stabilization treatment involves mixing an organophosphorus compound with an epoxy end-capping agent in a molar ratio of 1:0.1 and reacting the mixture at 60°C for 2 hours in the presence of an alkaline catalyst.

[0037] The catalytic synergist is selected from tetrabutyl titanate and tetraisopropyl titanate; The hydrolysis-resistant and stabilized organophosphorus compound and the catalytic synergist were mixed in a mass ratio of 5:1.

[0038] The molecular sieve microspheres were selected from X-type molecular sieves with a pore size of 3 Å and a particle size of 1 μm, and the addition amount was 1% of the mass of the matrix resin. The smoke suppressant compound composition, the phase change heat endothermic material microcapsule, and the catalytic char formation synergist composition were added to the matrix resin at proportions of 10%, 5%, and 8% of the matrix resin mass, respectively.

[0039] Continuous fibers are selected from glass fibers; After pretreatment, the continuous fibers were impregnated with a flame-retardant matrix resin composition for 30 minutes, and then cured at 120℃ and 0.2MPa for 2 hours. Example

[0040] The difference between this embodiment and Embodiment 1 is that: Metal hydroxides include aluminum hydroxide and magnesium hydroxide, mixed in a mass ratio of 1:2; The molybdenum-boron composite catalyst was prepared by mixing ammonium molybdate and boric acid in a mass ratio of 1:2. The metal hydroxide mixture and the molybdenum-boron composite catalyst were compounded at a mass ratio of 5:1.

[0041] The surface hydrophobic modification treatment involves heating the smoke suppressant compound at 120°C, adding a silane coupling agent at 5% of the total mass of the metal hydroxide, and reacting for 120 minutes at a rotation speed of 800 r / min, so that the modifier forms a hydrophobic molecular layer on the surface of the metal hydroxide.

[0042] The organic phase change material is selected from n-eicosane, n-docosane, palmitic acid, stearic acid, and polyethylene glycol, and the phase change temperature is 50℃. The phase transition temperature of inorganic salt phase change materials is 180℃.

[0043] The hydrophobic inorganic nanoparticles are selected from hydrophobic nano-alumina and hydrophobic nano-zinc oxide, with an addition amount of 15% of the total shell material and a particle size of 50 nanometers.

[0044] The in-situ polymerization method involves mixing an organic phase change material with a hybrid shell precursor solution composed of urea-formaldehyde resin prepolymer and inorganic filler at a core-shell mass ratio of 1:1. Under the action of an emulsifier concentration of 2.0 wt%, the urea-formaldehyde resin prepolymer undergoes a polycondensation reaction at a temperature of 80°C and a pH of 8.0 for 4 hours to obtain microcapsules with a particle size of 50 micrometers and an encapsulation rate greater than 85%.

[0045] Organophosphorus compounds are selected from triphenyl phosphate, tricresyl phosphate, and ammonium polyphosphate; The hydrolysis stabilization treatment involves mixing an organophosphorus compound with an epoxy end-capping agent in a molar ratio of 1:0.5 and reacting the mixture at 100°C for 4 hours in the presence of an alkaline catalyst.

[0046] The catalytic synergists are selected from iron oxide, zinc oxide, and nickel oxide; The hydrolysis-resistant and stabilized organophosphorus compound and the catalytic synergist were mixed in a mass ratio of 10:1.

[0047] The molecular sieve microspheres were selected from type A molecular sieves with a pore size of 5 Å and a particle size of 10 μm, and the addition amount was 5% of the mass of the matrix resin. The smoke suppressant compound composition, the phase change heat endothermic material microcapsule, and the catalytic char formation synergist composition were added to the matrix resin in proportions of 25%, 15%, and 20% of the matrix resin mass, respectively.

[0048] The continuous fibers are selected from carbon fiber, glass fiber, aramid fiber, and basalt fiber; After pretreatment, the continuous fibers were impregnated with a flame-retardant matrix resin composition for 60 minutes, and then cured at 180℃ and 1.0MPa for 4 hours. Example

[0049] This embodiment proposes a method for preparing a continuous fiber reinforced material, comprising the following steps: Step 1: Preparation of smoke suppressant compound composition Aluminum hydroxide and magnesium hydroxide are mixed in a mass ratio of 2:1 to 1:2, preferably 1.5:1, to obtain a metal hydroxide mixture.

[0050] Ammonium molybdate and boric acid are mixed in a mass ratio of 1:0.5-1:2, preferably 1:1, to obtain a molybdenum-boron composite catalyst.

[0051] The metal hydroxide mixture and the molybdenum-boron composite catalyst are mixed in a mass ratio of 10:1-5:1, preferably 7:1, and stirred in a high-speed mixer (1000-3000 r / min, 1-5 kW) for 30-60 min, preferably 45 min, to obtain the smoke suppressant compound composition.

[0052] Surface hydrophobic modification treatment of metal hydroxides: The above-mentioned smoke suppressant compound composition is heated under nitrogen protection at 80-120°C, preferably 100°C, and 2-5% (preferably 3%) of silane coupling agent (such as KH550: γ-aminopropyltriethoxysilane, purity ≥98%; or KH560: γ-glycidoxypropyltrimethoxysilane, purity ≥98%) or fatty acid (such as stearic acid: C) is added. 18 H 36 O2, melting point 69℃, purity ≥95%; or oleic acid: C 18 H 34 O2 (iodine value 85-105, purity ≥90%) is reacted under high-speed stirring conditions (speed 300-800 r / min, preferably 500 r / min) for 60-120 min, preferably 90 min, so that the modifier forms a chemically bonded hydrophobic molecular layer on the surface of the metal hydroxide. Then, it is cooled to room temperature to obtain a surface hydrophobic modified smoke suppressant compound composition.

[0053] This hydrophobic modification layer reduces the affinity between water molecules and the particle surface by forming a low surface energy molecular film on the hydroxide particle surface. When the relative humidity reaches above 80%, the water absorption of the modified hydroxide particles is reduced by 60-80% compared to the unmodified particles, thereby preventing particle aggregation and maintaining a good dispersion state. The effect of hydrophobic modification can be characterized by contact angle testing; the water contact angle of the modified particles increases from less than 20° before modification to greater than 120°.

[0054] Step 2: Preparation of microcapsules for phase change endothermic materials Organic phase change materials with a phase change temperature of 50-90℃ are selected as the core material. The organic phase change material can be one or more of n-eicosane, n-docosahexanes, palmitic acid, stearic acid, and polyethylene glycol, or inorganic salt phase change materials with a phase change temperature of 120-180℃, such as sodium acetate trihydrate, inorganic salt eutectic systems (such as potassium nitrate-sodium nitrate eutectic, mass ratio 60:40, phase change temperature about 150-180℃), etc.

[0055] Urea-formaldehyde resin is selected as the polymerizable organic shell material precursor, wherein the urea-formaldehyde resin precursor is composed of urea (CO(NH2)2, purity ≥99%, molecular weight 60.06) and formaldehyde (HCHO, 37% aqueous solution, containing ≤15% methanol stabilizer) in a molar ratio of 1:1.2-1:2.0 (preferably 1:1.5). One of the following is selected as the inorganic reinforcing filler: silica (SiO2, particle size 20-50 nm, specific surface area 200-400 m² / g, purity ≥99%), alumina (Al2O3, particle size 30-80 nm, specific surface area 80-200 m² / g, purity ≥99%), or silicon carbide (SiC, particle size 50-100 nm, purity ≥98%), with silica being preferred.

[0056] Preparation of shell precursor solution: First, prepare the urea-formaldehyde resin prepolymer: Dissolve urea in deionized water to prepare a 20-30 wt% (preferably 25 wt%) urea aqueous solution. Slowly add formaldehyde solution under stirring, controlling the reaction temperature at 40-60℃ (preferably 50℃), adjusting the pH to 8.0-9.0 (using sodium hydroxide solution), and the reaction time at 30-60 min (preferably 45 min), to obtain a transparent urea-formaldehyde resin prepolymer solution. The viscosity of the prepolymer should be controlled in the range of 50-200 mPa·s, and the solid content should be controlled in the range of 15-25 wt%.

[0057] Then, an organic-inorganic hybrid shell material precursor solution is prepared: the obtained urea-formaldehyde resin prepolymer solution is compounded with inorganic reinforcing filler (preferably silica) at a mass ratio of 3:1-1:1 (preferably 2:1), and a dispersant is added at a mass of 0.5-2.0% (preferably 1.0%) of the total inorganic filler. The dispersant can be selected from one of polyvinylpyrrolidone (PVP, molecular weight 8000-40000), polyacrylic acid (PAA, molecular weight 2000-5000), and sodium hexametaphosphate (SHMP, purity ≥68%). Stir at 500-1000 rpm for 30-60 min at room temperature, then disperse using a high-shear disperser (8000-15000 rpm, preferably 10000 rpm) for 20-40 min (preferably 30 min), or use an ultrasonic disperser (300-800 W, 20-40 kHz) for 15-30 min to obtain a homogeneous and stable hybrid shell precursor solution. The obtained solution should show no obvious agglomeration, the inorganic filler particle size distribution D50 should be controlled within the range of 50-200 nm, and the solution pH should be adjusted to 6.5-8.5 (preferably 7.5), which can be done using dilute hydrochloric acid. The obtained shell precursor solution should be used within 4 h, or stored at 4 °C for no more than 24 h.

[0058] In the prepared hybrid shell precursor solution, 5-15% (preferably 10%) of hydrophobic inorganic nanoparticles by mass are further added to the total shell material. The hydrophobic inorganic nanoparticles are selected from one or more of the following: silane-treated hydrophobic nano-silica (particle size 10-30 nm, specific surface area 150-300 m² / g, contact angle >120° after hydrophobic treatment), hydrophobic nano-alumina (particle size 20-40 nm, specific surface area 80-150 m² / g), and hydrophobic nano-zinc oxide (particle size 15-35 nm, purity ≥99%). The nanoparticles are then ultrasonically dispersed for 10-20 min to ensure uniform dispersion.

[0059] Microcapsules are prepared by in-situ polymerization: an organic phase change material and a hybrid shell material precursor solution are mixed at a core-shell mass ratio of 1:0.3-1:1 (preferably 1:0.5). A stable emulsion is formed under the action of a nonionic emulsifier (such as polyvinyl alcohol PVA, degree of polymerization 1000-2000, degree of saponification 87-89%; or Tween-80, HLB value 15.0) at a concentration of 0.5-2.0 wt% at a temperature of 20-30℃ and a stirring speed of 800-1500 r / min. Then, by controlling the reaction temperature at 60-80℃ (preferably 70℃) and the pH value at 6.0-8.0 (preferably 7.0), the urea-formaldehyde resin prepolymer undergoes a polycondensation reaction, which is cured on the surface of the phase change material to form a composite shell structure containing inorganic fillers for 2-4 hours (preferably 3 hours). In this process, urea and formaldehyde undergo a condensation reaction to generate a three-dimensional cross-linked urea-formaldehyde resin network structure, and inorganic nanofillers are uniformly dispersed in the polymer matrix to play a reinforcing role. The particle size of the prepared microcapsules should be controlled in the range of 5-50 micrometers (preferably 10-30 micrometers), the encapsulation efficiency should be greater than 85%, and the surface morphology should be spherical and without obvious defects.

[0060] Hydrophobic inorganic nanoparticles play a triple role in the shell: First, the nanoparticles fill the molecular gaps and micropores of the polymer shell, increasing the shell density from 85% to over 95% and reducing the porosity to below 5%; Second, the surface contact angle of the hydrophobic nanoparticles is greater than 110°, forming hydrophobic channels and reducing the diffusion coefficient of water molecules in the shell by 2-3 orders of magnitude; Third, the nanoparticles, as a reinforcing phase, form a physical cross-linking network with the polymer matrix, increasing the tensile strength of the shell by 40-60% and the elastic modulus by 30-50%, and no visible cracks are generated after 500 temperature cycles from -40℃ to 80℃.

[0061] Step 3: Preparation of catalytic char formation synergist composition Organophosphorus compounds are selected as the main char-forming catalysts, and the organophosphorus compounds may be one or more of triphenyl phosphate, tricresyl phosphate, and ammonium polyphosphate.

[0062] Transition metal compounds are selected as catalytic synergists. The transition metal compounds may be one or more of iron oxide, zinc oxide, and nickel oxide, or organometallic compounds such as tetrabutyl titanate and tetraisopropyl titanate may be selected as catalytic synergists.

[0063] Hydrolysis stabilization treatment of organophosphorus compounds: Safety precautions: Due to the toxicity and carcinogenicity of epichlorohydrin (ECH) and the strong irritant and corrosive nature of triethylamine, operations must be carried out in a fume hood. Operators must wear protective eyewear, chemical-resistant gloves, and protective clothing. Reaction vessels should be made of corrosion-resistant materials (such as glass or PTFE coating), and explosion-proof thermometers should be used for temperature monitoring.

[0064] Organophosphorus compounds are mixed with epoxy-terminated agents (bisphenol A diglycidyl ether (DGEBA), with a molecular weight of 380-400, epoxy value of 0.51-0.53 mol / 100g, and purity ≥98%, which has low toxicity is recommended; if epichlorohydrin (ECH) is used, with a molecular weight of 92.52, epoxy value of 1.08 mol / 100g, and purity ≥99%, stronger protection is required) in a molar ratio of 1:0.1-1:0.5 (preferably 1:0.3), and then mixed with an alkaline catalyst (such as triethylamine (TEA), molecular formula C6H) in a molar ratio of 1:0.1-1:0.5 (preferably 1:0.3). 15 In the presence of 0.1-0.5wt% N (boiling point 89℃, purity ≥99%), the mixture is reacted at 60-100℃ (preferably 80℃) for 2-4 hours (preferably 3 hours) under nitrogen protection.

[0065] pH safety control: The pH value should be strictly controlled within the range of 8.5-9.5 during the reaction to avoid side reactions caused by excessively high pH. If the pH exceeds 10, it should be immediately adjusted to a safe range with dilute acetic acid. The temperature and pH of the reaction system should be continuously monitored. If any abnormality occurs, heating should be stopped immediately and the system cooled down. The reaction involves a ring-opening addition reaction between the epoxy group and the active groups (such as hydroxyl and amino groups) at the molecular chain end of the organophosphorus compound, forming stable ether or amine bonds, thus sealing the active end groups and obtaining a hydrolysis-resistant and stabilized organophosphorus compound.

[0066] A hydrolysis-resistant stabilized organophosphorus compound is mixed with a catalytic synergist (transition metal compound or organometallic compound) at a mass ratio of 5:1-10:1 and fully dispersed using a ball mill or high-speed shearing device to obtain a catalytic char-forming synergist composition. The chemical reaction process of epoxy end-capping treatment: The polar groups such as hydroxyl and amino groups at the molecular chain ends of organophosphorus compounds are prone to hydrolysis in the presence of moisture, leading to a decrease in catalytic activity.

[0067] The epoxy group undergoes a ring-opening addition reaction with these polar groups to form a stable COC ether bond or CNC amine bond, transforming the hydrophilic end group into a hydrophobic end group. As a result, after the modified organophosphorus compound is placed in an environment with a relative humidity of 90% for 30 days, the catalytic activity retention rate is still greater than 85%, while the unmodified organophosphorus compound retains only 40-50% of its activity under the same conditions.

[0068] Solvent recovery and waste disposal: Organic solvent recovery: The ethanol solvent used in the reaction process is recovered by vacuum distillation, with a recovery rate of over 95%. Distillation conditions: vacuum degree -0.08MPa, temperature 50-60℃. The recovered ethanol can be reused after purity testing (≥99%).

[0069] Recovery of valuable reagents: Titanate catalysts can be recovered by the following method: the mixture after reaction is extracted three times with n-hexane (each time the amount of reactants is 1 / 3), the extracts are combined, and the solvent is removed by vacuum distillation to obtain crude titanate with a purity of about 85-90% and a recovery rate of about 70-80%, which can be used for the next batch of production.

[0070] Waste disposal: Waste containing organophosphates must not be discharged directly; it should be collected and sent to a qualified hazardous waste treatment unit for treatment. Waste liquid containing triethylamine should first be neutralized to pH 6-8 with dilute hydrochloric acid, then treated with activated carbon adsorption before being discharged in compliance with standards. Solid waste should be dried and treated according to hazardous waste disposal regulations.

[0071] Intermediate product storage conditions: Hydrophobic modified smoke suppressant compound compositions should be stored in airtight containers at a temperature controlled between 5-25℃ and relative humidity <60%, protected from light, with a shelf life not exceeding 6 months. Phase change microcapsules should be stored in a dry environment (relative humidity <40%) at a temperature of 10-30℃, avoiding mechanical impact. Catalytic char formation synergist compositions should be stored in sealed containers under nitrogen protection at a storage temperature <40℃, with a shelf life of 12 months.

[0072] Step 4: Preparation of flame-retardant matrix resin composition The matrix resin can be selected from epoxy resins (such as bisphenol A type epoxy resin E51, epoxy value 0.48-0.54 mol / 100g, viscosity 10-16 Pa·s / 25℃, softening point 64-76℃), unsaturated polyester resins (such as isophthalic acid type UPR, acid value ≤25mgKOH / g, viscosity 0.4-0.8 Pa·s / 25℃, styrene content 35-45%), vinyl ester resins (VE, epoxy value ≤25mgKOH / g, viscosity 0.4-0.8 Pa·s / 25℃, styrene content 35-45%), or vinyl ester resins (VE, epoxy value ≤25mgKOH / g, viscosity 0.4-0.8 Pa·s / 25℃, styrene content 35-45%). One or more of the following: 0.22-0.26 mol / 100g, viscosity 0.45-0.65 Pa·s / 25℃; phenolic resin (PF, free phenol content ≤5%, free formaldehyde content ≤0.5%); polyamide (PA6, relative molecular weight 15000-30000, melting point 215-225℃); and polypropylene (PP, melt flow rate 10-35 g / 10 min, density 0.90-0.91 g / cm³).

[0073] Molecular sieve microspheres are added to the matrix resin as a moisture control agent. The molecular sieve microspheres are selected from type A or type X molecular sieves with a pore size of 3-5 angstroms and a particle size of 1-10 micrometers. The amount added is 1-5% of the mass of the matrix resin.

[0074] Physicochemical compatibility analysis: Solubility and dispersibility: The hydrophobically modified smoke suppressant exhibits good dispersibility in epoxy resin, with a sedimentation rate of <0.1 mm / h (24-hour standing test). The phase change microcapsules are uniformly suspended in the resin, with a particle size distribution D50 of 15-25 μm and a dispersion index PDI <0.3. The catalytic char-forming agent has a solubility of 8-15 g / 100 g (25℃) in the resin system, with the excess portion exhibiting a stable dispersion.

[0075] pH stability: The pH compatibility of each component in the resin system is as follows: the smoke suppressant compound composition is stable in the pH range of 6-9 without precipitation; the phase change microcapsules maintain shell integrity of >95% in the pH range of 5-10; the charring agent has the best catalytic activity in the pH range of 7-8.5, and partial hydrolysis will occur at pH <6.

[0076] Thermal stability matching: The thermal decomposition temperature of each component is matched with the matrix resin. The initial decomposition temperature of the smoke suppressant is 300℃, the phase change material is 50-180℃, and the activation temperature of the charring agent is 250℃, all of which are lower than the decomposition temperature of the matrix resin (>350℃), ensuring that the flame retardant function takes precedence over the decomposition of the matrix.

[0077] The regulatory function of molecular sieve microspheres: Utilizing their 3-5 Å microporous structure, they selectively adsorb water molecules (water molecules are approximately 2.8 Å in diameter). Within a relative humidity range of 50-90%, molecular sieve microspheres can adsorb 15-25% of their own mass in water. When the ambient humidity increases, the molecular sieve preferentially adsorbs excess water; when the ambient humidity decreases, the molecular sieve releases the stored water. Through this dynamic adsorption-release process, the local relative humidity around each flame-retardant component is maintained within a suitable range of 60±10%, ensuring that the hydroxide smoke suppressant remains well dispersed, the phase change microcapsule interface is stably bonded, and the catalytic activity of the charring agent does not decrease due to excessive drying.

[0078] The smoke suppressant compound composition prepared in step one, the phase change heat-absorbing material microcapsules prepared in step two, and the catalytic char-forming synergist composition prepared in step three are added to the matrix resin in the following proportions: 10-25%, 5-15%, and 8-20% of the matrix resin mass, respectively. The mixture is stirred for 60-120 minutes using a planetary mixer at a speed of 200-500 r / min to ensure that each component is uniformly dispersed in the matrix, thereby obtaining the flame-retardant matrix resin composition.

[0079] Step 5: Preparation of continuous fiber reinforced materials Select continuous fibers, which may be selected from one or more of the following: carbon fiber (T300 grade, tensile strength 3530MPa, tensile modulus 230GPa, fiber diameter 7μm, number of monofilaments 3000-12000 / bundle), glass fiber (E glass fiber, tensile strength 3400-4800MPa, tensile modulus 72-75GPa, fiber diameter 10-24μm), aramid fiber (Kevlar49, tensile strength 3600-4100MPa, tensile modulus 112-120GPa, fiber diameter 12μm), and basalt fiber (continuous basalt fiber, tensile strength 3000-4840MPa, tensile modulus 79-93GPa, fiber diameter 9-15μm).

[0080] To improve the bonding strength between the continuous fibers and the matrix, the surface oil is first removed by ultrasonic cleaning with acetone or ethanol for 15-30 minutes. Then, surface activation is performed using a silane coupling agent (KH550, 0.5-2.0 wt% ethanol solution) or plasma treatment (100-500W power, 30-180s). The contact angle of the pretreated fiber surface should be less than 30°, and the surface energy should be greater than 40 mN / m. The pretreated continuous fibers are then impregnated in the aforementioned flame-retardant matrix resin composition for 30-60 minutes (preferably 45 minutes) at a temperature between room temperature and 60°C, ensuring that the resin fully penetrates the fiber bundle. The resin content should be controlled within the range of 25-45 wt%.

[0081] After impregnation, the fibers are laid up. Depending on the flame retardant performance requirements, an additional smoke suppressant compound coating can be applied between the key fiber layers, with a coating thickness of 50-200 micrometers. The function of this interlayer coating is to form a high-concentration smoke suppressant enrichment zone at the interlayer interface. When a fire occurs, it preferentially produces a smoke suppressant effect between the layers, preventing the spread of flames between the layers. It forms a dual protective structure of "matrix dispersion + interface enrichment" with the uniformly dispersed flame retardant components in the matrix resin. The smoke suppressant compound composition used in the interlayer coating can be the product prepared in step one, or the content of the molybdenum-boron composite catalyst can be adjusted as needed.

[0082] The laid-up material is cured using processes such as compression molding, pultrusion molding, or filament winding. Curing conditions are determined based on the type of matrix resin, typically 120-180℃ (preferably 150℃) for 2-4 hours (preferably 3 hours), with a curing pressure of 0.2-1.0 MPa (preferably 0.5 MPa). Criteria for determining complete curing include: a smooth, bubble-free material surface; a Barcol hardness of 35-45; and a glass transition temperature 50-80℃ higher than before curing. After curing, the material is demolded to obtain a continuous fiber-reinforced material.

[0083] Specific examples: Example 1 (Example of the present invention): 30g of aluminum hydroxide (particle size 3 μm, purity 99.2%) and 20g of magnesium hydroxide (particle size 2 μm, purity 96%) were mixed at a mass ratio of 1.5:1 to obtain a metal hydroxide mixture. 3g of ammonium molybdate (purity 99.5%) and 3g of boric acid (purity 99.8%) were mixed at a mass ratio of 1:1 to obtain a molybdenum-boron composite catalyst. The above two components were mixed at a mass ratio of 7:1 and stirred for 45 min using a high-speed mixer (2000 r / min) to obtain a smoke suppressant composite composition. Under nitrogen protection, the mixture was heated to 100°C, and 1.5g of KH550 (purity 98.5%) was added. The mixture was stirred at 500 r / min for 90 min and cooled to room temperature to obtain a hydrophobic modified smoke suppressant composite composition with a water contact angle of 126°.

[0084] Preparation of phase change microcapsules: 10g of n-eicosane (98% purity) was used as the core material, 5g of silica precursor was used as the shell material, and 0.5g of hydrophobic nano silica was used. The mixture was polymerized for 3h at 70℃ and pH=7.0 under the action of PVA emulsifier (1.0wt%) to obtain phase change microcapsules with a microcapsule size of 25 micrometers and an encapsulation rate of 89%.

[0085] Preparation of catalytic char-forming agent: 15g of ammonium polyphosphate (phosphorus content 31.5%) and 2.25g of DGEBA (epoxide value 0.52mol / 100g) were mixed at a molar ratio of 1:0.3, and 0.15g of triethylamine was added. The mixture was reacted at 80℃ for 3h, and the conversion rate of epoxy groups was 92% as determined by infrared spectroscopy. Then, 2g of iron oxide nanoparticles (particle size 100 nm) were mixed at a mass ratio of 7.5:1 and dispersed by ball milling to obtain the catalytic char-forming synergist.

[0086] Preparation of flame-retardant matrix resin: Take 100g of epoxy resin E51 (epoxy value 0.51mol / 100g), add 3g of molecular sieve microspheres (type A, pore size 4 Å), then add 18g of smoke suppressant compound composition, 10g of phase change microcapsules, and 12g of catalytic charring agent in sequence. Mix in a planetary mixer at 300r / min for 90min to obtain the flame-retardant matrix resin composition.

[0087] Carbon fibers (T300, 3K) were selected and treated with KH550. The resin was impregnated for 45 minutes, and after layup, the fibers were cured at 150°C and 0.5 MPa for 3 hours to obtain a continuous fiber-reinforced material.

[0088] Comparison Example: Comparative Example 1 (with only smoke suppressant): The material was prepared using the same method, but only 18g of the smoke suppressant compound was added; phase change microcapsules and catalytic charring agents were not added. Test results: Oxygen index 28.5, smoke density grade Ds=120, tensile strength 835MPa, flexural strength 1180MPa.

[0089] Comparative Example 2 (with only phase change material added): The material was prepared using the same method, but only 10g of phase change microcapsules were added, without smoke suppressants or charring catalysts. Test results: Oxygen index 26.8, smoke density grade Ds=380, tensile strength 850MPa, flexural strength 1200MPa.

[0090] Comparative Example 3 (with only catalytic charring agent added): The material was prepared using the same method, but only 12g of catalytic charring agent was added; no smoke suppressant or phase change material was added. Test results: Oxygen index 30.1, smoke density grade Ds=280, tensile strength 840MPa, flexural strength 1190MPa.

[0091] Comparison with Example 4 (conventional flame retardant): Using the same carbon fiber and matrix resin, an equal amount (40g) of conventional aluminum hydroxide flame retardant was added. Test results: Oxygen index 24.3, smoke density rating Ds=450, tensile strength 798MPa, flexural strength 1089MPa.

[0092] Synergistic effect verification: Example 1: Final performance test results: Oxygen index 34.2, smoke density rating Ds=68, tensile strength 862MPa, flexural strength 1256MPa. After being placed in an environment of 85℃ and 85% relative humidity for 6 months, the oxygen index retention rate was 88%.

[0093] Synergistic effect analysis: The individual effects of Examples 1, 2, and 3 were: oxygen index improvement of +6.5, +4.8, and +8.1, respectively; smoke density improvement of +330, +70, and +170, respectively. The synergistic effect of Example 1 was: oxygen index improvement of +12.2 and smoke density improvement of +382, which was significantly better than the simple sum of the three individual effects (the theoretical value of +19.4 vs. the actual value of +12.2 indicates the existence of negative synergy, but the overall performance optimization is significant).

[0094] Verification Experiment Experiment 1: Verification Experiment of the Synergistic Flame Retardant Effect of Ternary Elements 1. Experimental Objective The synergistic effect of the three-component flame retardant system, consisting of a smoke suppressant compound composition, a phase change endothermic material microcapsule, and a catalytic char-forming synergist composition, compared to a single flame retardant component was verified, and the synergistic improvement effect on oxygen index and smoke density level was tested.

[0095] 2. Preparation of experimental samples The following samples were prepared according to the method of Embodiment 1: Sample A: An embodiment of the present invention (containing all three flame-retardant components); Sample B: Contains only a smoke suppressant compound composition (18wt%). Sample C: Contains only phase change microcapsules (10wt%); Sample D: Contains only catalytic char-forming agent (12wt%); Sample E: Traditional aluminum hydroxide flame retardant (40wt%); Sample F: Blank control (no flame retardant); All samples used the same carbon fiber (T300, 3K) and epoxy resin (E51) matrix, with a fiber volume fraction of 60% and a sample size of 150mm × 6.5mm × 3.2mm.

[0096] 3. Experimental conditions Oxygen index test: According to GB / T 2406.2-2009 standard, the test environment temperature is 23±2℃ and the relative humidity is 50±5%. Smoke density test: According to GB / T 8627-2007 standard, the combustion chamber volume is 27m³ and the test time is 4min.

[0097] 4. Experimental Procedure (1) Oxygen index test: The sample is held vertically in the combustion cylinder, the concentration of oxygen-nitrogen mixture is adjusted, the top of the sample is ignited, the combustion behavior is observed, and the minimum oxygen concentration required to maintain combustion is recorded.

[0098] (2) Smoke density test: The sample is placed in the smoke density test chamber and ignited with a radiant heat source (25kW / m²). The optical density value of the smoke is measured within 4 minutes.

[0099] (3) Five parallel samples were tested for each group of samples, and the average value was taken.

[0100] 5. Experimental or test results Table 1. Test results of flame retardant properties of different samples

[0101] Figure 1 A comparison of oxygen indexes was shown; Figure 2 A comparison of smoke density levels was displayed; Figure 3 The comparison of char layer thickness after combustion is shown.

[0102] 6. Analysis and Summary Experimental results show that the ternary synergistic flame retardant system of this invention has significant advantages over single flame retardant components and traditional flame retardants: (1) Significant synergistic effect: The oxygen index of sample A of the present invention reached 34.2%, which is 4-7 percentage points higher than that of the sample containing only a single component, confirming the effectiveness of the ternary synergistic mechanism.

[0103] (2) Outstanding smoke suppression effect: The smoke density level Ds is reduced to 68, which is 85% lower than the 450 of traditional flame retardants, greatly improving visibility and safety in a fire.

[0104] (3) Significant char formation efficiency: The char layer thickness reaches 4.2 mm, which is 5.25 times that of traditional flame retardants, forming an effective oxygen barrier layer.

[0105] (4) Excellent overall performance: It has achieved synergistic optimization in three key indicators: oxygen index, smoke density and char layer formation, and has reached the Class A flame retardant standard.

[0106] Experiment 2: Long-term stability test of flame retardant performance under humid and hot conditions 1. Experimental Objective The invention verifies the technical effect of maintaining stable flame retardant performance of the material in a high humidity and high temperature environment through surface hydrophobic modification, anti-hydrolysis stabilization treatment and moisture control, and compares the performance degradation of traditional flame retardant materials.

[0107] 2. Preparation of experimental samples Prepare the following comparative samples: Sample 1: Embodiment of the present invention (containing hydrophobic modified smoke suppressant + anti-hydrolysis charring agent + molecular sieve regulator). Sample 2: Unmodified control group (containing unmodified aluminum hydroxide + uncapped organophosphorus compounds); Sample 3: Traditional flame-retardant composite material (containing only 40wt% aluminum hydroxide); All samples were flat plate specimens measuring 100mm×100mm×4mm, with 30 specimens prepared for testing at different time points in each group.

[0108] 3. Experimental conditions Damp heat aging conditions: temperature 85±2℃, relative humidity 85±5%, performed according to GB / T 2573-2008 standard. Test time points: 0, 1, 2, 3, 6, 9, and 12 months. Five parallel samples were tested at each time point, and the average value was taken.

[0109] 4. Experimental Procedure (1) Damp heat aging treatment: The samples were placed in a constant temperature and humidity chamber, and the temperature was set to 85℃ and the relative humidity to 85% for 1, 2, 3, 6, 9 and 12 months respectively.

[0110] (2) Performance testing: The samples were taken out at the specified time points and allowed to equilibrate at room temperature for 24 hours before the following tests were performed: Oxygen index test (GB / T 2406.2); Smoke density rating test (GB / T 8627).

[0111] 5. Experimental or test results Table 2 Changes in flame retardant properties during damp heat aging

[0112] Table 3 Performance retention rate after 12 months of damp heat aging

[0113] 6. Analysis and Summary The results of the damp heat aging test fully verify the long-term stability advantage of the technology of this invention: (1) Excellent performance retention rate: After 12 months of damp heat aging, the oxygen index retention rate of the sample of this invention reached 88.0% and the smoke density retention rate reached 85.2%, which is far superior to the unmodified sample and traditional flame retardant materials.

[0114] (2) Effectively suppress performance degradation: Traditional flame retardant materials show significant performance degradation after 6 months, while the material of the present invention only shows slight degradation during the same period, which proves the effectiveness of hydrophobic modification and anti-hydrolysis treatment.

[0115] (3) Molecular sieve regulation effect: Through the water regulation effect of molecular sieve microspheres, the competitive adsorption of water among multiple components is effectively avoided, and the synergistic flame retardant effect is maintained.

[0116] Experiment 3: Synergistic Cooling Effect of Rapid Carbonization and Phase Change Endothermic Effect 1. Experimental Objective The synergistic mechanism of the phase change endothermic material microcapsule and the catalytic char formation enhancer composition in this invention was verified. The temperature change, char formation rate and heat absorption effect during the combustion process were measured to demonstrate the synergistic cooling effect of rapid char formation and phase change endothermic technology.

[0117] 2. Preparation of experimental samples Prepare the following comparative samples: Sample α: Complete formulation of this invention (containing 10wt% phase change microcapsules + 12wt% catalytic charging agent); Sample β: Contains only phase change microcapsules (10wt%); Sample γ: Contains only catalytic char-forming agent (12wt%); Sample δ: Blank matrix (without flame retardant additives).

[0118] All samples were prepared using the same carbon fiber and epoxy resin matrix, and were made into test specimens of 80mm×80mm×5mm.

[0119] 3. Experimental conditions Combustion test: Cone calorimeter (ISO 5660 standard), thermal radiation intensity 50kW / m²; Test environment: temperature 23±2℃, relative humidity 50±5%; Real-time monitoring: surface temperature, heat release rate, mass loss, smoke generation; Test time: 300s 4. Experimental Procedure (1) Cone calorimeter test: The sample is placed horizontally in the cone calorimeter and ignited with 50kW / m² thermal radiation. The combustion parameters are recorded in real time.

[0120] (2) Infrared thermal imaging: Infrared thermal imager is used to monitor the temperature distribution and changes on the sample surface in real time.

[0121] (3) Differential scanning calorimetry: to determine the latent heat of phase change of phase change material and the decomposition heat effect of char-forming agent.

[0122] 5. Experimental or test results Table 4 Comparison of key parameters during combustion

[0123] Table 5. Synergistic effect analysis of phase change endothermic reaction and char formation

[0124] Table 6 DSC Analysis Results of Phase Change Materials

[0125] 6. Analysis and Summary The experimental results fully demonstrate the synergistic cooling mechanism of phase change endothermic reaction and rapid char formation: (1) Significant cooling effect: The synergistic system of the present invention reduces the highest surface temperature during combustion from 950°C to 625°C, a cooling effect of 325°C, which is 41.3% better than the cooling effect of single technology.

[0126] (2) Synergistic effect mechanism: The phase change material absorbs latent heat of 232J / g in stages within the temperature range of 50-180℃, effectively delaying the temperature rise; at the same time, it creates a suitable reaction temperature environment for the catalytic carbonization agent, promoting the rapid formation of a dense carbon layer.

[0127] (3) Phase change material protection: The rapid formation of the carbonized layer protects the phase change microcapsules from high temperature damage, maintaining the latent heat utilization rate of phase change at a high level of 85.6%, and realizing a virtuous cycle of phase change heat absorption and carbonization barrier.

[0128] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A method for preparing a continuous fiber reinforced material, characterized in that, Includes the following steps: Step 1: Preparation of smoke suppressant compound composition: After compounding metal hydroxide with a molybdenum-boron composite catalyst, the surface of the metal hydroxide is modified by hydrophobic treatment using a silane coupling agent or fatty acid to obtain a surface-hydrophobic modified smoke suppressant compound composition. Step 2: Preparation of phase change endothermic material microcapsules: Microcapsules of phase change endothermic materials were prepared by in-situ polymerization using organic phase change materials or inorganic salt phase change materials as the core material and organic-inorganic hybrid materials containing hydrophobic inorganic nanoparticles, composed of urea-formaldehyde resin prepolymer and inorganic fillers, as the shell material. Step 3: Preparation of catalytic char formation synergist composition: After the organophosphorus compound and the epoxy group end-capping agent are subjected to anti-hydrolysis stabilization treatment, they are compounded with a catalytic synergist to obtain a catalytic char formation synergist composition; Step 4: Preparation of flame-retardant matrix resin composition: Molecular sieve microspheres are added to the matrix resin as a moisture-absorbing regulator, and the components prepared in steps 1-3 are dispersed in the matrix resin to obtain a flame-retardant matrix resin composition. Step 5: Preparation of continuous fiber-reinforced materials: A continuous fiber reinforced material is obtained by combining a continuous fiber with a flame-retardant matrix resin composition and then curing it.

2. The preparation method according to claim 1, characterized in that, The metal hydroxide comprises aluminum hydroxide and magnesium hydroxide, mixed in a mass ratio of 2:1 to 1:2; the molybdenum-boron composite catalyst is prepared by mixing ammonium molybdate and boric acid in a mass ratio of 1:0.5 to 1:2; the metal hydroxide mixture and the molybdenum-boron composite catalyst are compounded in a mass ratio of 10:1 to 5:

1.

3. The preparation method according to claim 1, characterized in that, The surface hydrophobic modification treatment involves heating the smoke suppressant compound at 80-120°C, adding 2-5% by mass of a silane coupling agent or fatty acid of the total metal hydroxide content, and reacting at a speed of 300-800 r / min for 60-120 min, so that the modifier forms a hydrophobic molecular layer on the surface of the metal hydroxide.

4. The preparation method according to claim 1, characterized in that, The organic phase change material is selected from one or more of n-eicosane, n-docosahexanes, palmitic acid, stearic acid, and polyethylene glycol, with a phase change temperature of 50-90℃; the inorganic salt phase change material is selected from sodium acetate trihydrate or potassium nitrate-sodium nitrate eutectic system, with a phase change temperature of 120-180℃.

5. The preparation method according to claim 1, characterized in that, The hydrophobic inorganic nanoparticles are selected from one or more of hydrophobic nano-silica, hydrophobic nano-alumina, and hydrophobic nano-zinc oxide, and the amount added is 5-15% of the total shell material, with a particle size of 10-50 nanometers.

6. The preparation method according to claim 1, characterized in that, The in-situ polymerization method involves mixing an organic phase change material with a hybrid shell precursor solution composed of urea-formaldehyde resin prepolymer and inorganic filler at a core-shell mass ratio of 1:0.3-1:

1. Under the action of an emulsifier concentration of 0.5-2.0 wt%, the urea-formaldehyde resin prepolymer undergoes a polycondensation reaction at a temperature of 60-80℃ and a pH value of 6.0-8.0 for 2-4 hours to obtain microcapsules with a particle size of 5-50 micrometers and an encapsulation rate greater than 85%.

7. The preparation method according to claim 1, characterized in that, The organophosphorus compound is selected from one or more of triphenyl phosphate, tricresyl phosphate, and ammonium polyphosphate; the epoxy end-capping agent is selected from epichlorohydrin or bisphenol A diglycidyl ether; the hydrolysis stabilization treatment is to mix the organophosphorus compound and the epoxy end-capping agent in a molar ratio of 1:0.1-1:0.5 and react them at 60-100℃ for 2-4 hours in the presence of an alkaline catalyst.

8. The preparation method according to claim 1, characterized in that, The catalytic synergist is selected from one or more transition metal compounds among iron oxide, zinc oxide, and nickel oxide, or from one or more organometallic compounds among tetrabutyl titanate and tetraisopropyl titanate; the hydrolysis-resistant and stabilized organophosphorus compound is mixed with the catalytic synergist in a mass ratio of 5:1 to 10:

1.

9. The preparation method according to claim 1, characterized in that, The molecular sieve microspheres are selected from type A or type X molecular sieves with a pore size of 3-5 angstroms and a particle size of 1-10 micrometers, and the addition amount is 1-5% of the mass of the matrix resin; the smoke suppressant compound composition, the phase change heat endothermic material microcapsule, and the catalytic char formation synergist composition are added to the matrix resin in proportions of 10-25%, 5-15%, and 8-20% of the mass of the matrix resin, respectively.

10. The preparation method according to claim 1, characterized in that, The continuous fiber is selected from one or more of carbon fiber, glass fiber, aramid fiber, and basalt fiber. After pretreatment, the continuous fiber is impregnated and compounded with a flame-retardant matrix resin composition for 30-60 minutes, and then cured at 120-180℃ and 0.2-1.0MPa for 2-4 hours.

Images