Fiber-reinforced flame-retardant plastic and preparation method thereof

Abstract

The present invention relates to a fiber-reinforced flame-retardant plastic and a preparation method thereof, and belongs to the technical field of polymer materials. The fiber-reinforced flame-retardant plastic comprises, by weight, 60-80 parts of polycarbonate, 20-30 parts of titanium dioxide, 20-30 parts of glass fiber, 2-8 parts of heat-resistant modifier, 0.1-2 parts of modified flame retardant, and 1-3 parts of lubricant; the pyrophosphate piperazine compound in the modified flame retardant plays a carbon source role, collaborates with the phosphorus-nitrogen flame retardant, constructs an expanded carbon layer, effectively blocks oxygen and fire sources, and the phosphorus element of dimethyl chlorophosphate forms a phosphate protective layer to inhibit the spread of flame; the maleimide group in the heat-resistant modifier enhances intermolecular interaction, increases the glass transition temperature and melting point, and improves toughness; the sulfone group of the intermediate absorbs electrons, enhances thermal stability, and collaborates with phosphite to improve heat resistance; the fiber-reinforced flame-retardant plastic prepared by the present invention not only has excellent flame retardant and high temperature resistance, but also has a good toughening effect.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a fiber-reinforced flame-retardant plastic and a preparation method thereof. Background Art

[0002] At present, a large number of electrical components are made of flame-retardant plastics. With the improvement of environmental awareness and the rapid progress of science and technology, the market demand for high-strength, flame-retardant and durable plastics is growing.

[0003] Polycarbonate, a thermoplastic engineering plastic with excellent comprehensive performance, has high transparency, good toughness and weather resistance at room temperature due to the carbonate-based structure in its molecular chain. It is widely used in automobile manufacturing, electronic equipment, medical devices and other fields. However, when the temperature changes, the molecular chain activity of traditional polycarbonate materials is restricted, and they will transform from a highly elastic state to a glassy state, resulting in a significant decrease in toughness and susceptibility to embrittlement and cracking, thus limiting their application under high temperature conditions. In addition, although polycarbonate plastic has certain flame retardant properties, its own electrical conductivity no longer meets the requirements as the actual application requirements increase. Therefore, the development of a fiber-reinforced flame-retardant plastic with excellent performance has important practical significance and application value. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a fiber-reinforced flame-retardant plastic and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A fiber-reinforced flame-retardant plastic, comprising the following raw materials in parts by weight: 60-80 parts of polycarbonate, 20-30 parts of titanium dioxide, 20-30 parts of glass fiber, 2-8 parts of a heat-resistant modifier, 0.1-2 parts of a modified flame retardant, and 1-3 parts of a lubricant;

[0007] The lubricant is pentaerythritol stearate.

[0008] The modified flame retardant is prepared by the following method:

[0009] Step A1: Anhydrous sodium carbonate and deionized water were stirred uniformly, heated to 80°C, and then anhydrous piperazine and dimethyl chlorophosphate were added and mixed. The mixture was reacted for 8 hours, allowed to stand, filtered, washed, and dried in vacuo. Under a nitrogen atmosphere, 1,3-propylenediamine was added, stirred at 100°C for 30 minutes, condensed and refluxed at 140°C for 8 hours, and rotary evaporated to obtain the compound;

[0010] Furthermore, the usage ratio of anhydrous sodium carbonate, deionized water, anhydrous piperazine, dimethyl chlorophosphate, and 1,3-propylenediamine is 5.3-10.6 g: 20-50 mL: 2.15-4.3 g: 7.47-14.94 g: 7.41-14.82 g;

[0011] First, anhydrous piperazine reacts with the chlorine atom of dimethyl chlorophosphate, and the amino group of 1,3-propylenediamine reacts with dimethyl chlorophosphate to generate a compound;

[0012] Step A2: 3-Butenetriethoxysilane and ethanol were mixed, stirred at 80° C. for 10 h, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, stirred for 12 h, cooled to room temperature, filtered, and washed to obtain a pre-product;

[0013] Furthermore, the usage ratio of 3-butenetriethoxysilane, ethanol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 0.04-0.08 mol: 100-200 mL: 0.04-0.08 mol;

[0014] Secondly, the carbon-carbon double bond of 3-butenetriethoxysilane is reacted with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to generate a pre-product;

[0015] Step A3: After mixing the pre-product and the ethanol-water mixed solution at 35° C. for 10 minutes, the compound is added, and the mixture is reacted at 100° C. for 5 hours. The heating is stopped, and the mixture is naturally cooled to room temperature while stirring, filtered, washed, and dried to obtain a modified flame retardant;

[0016] Furthermore, the ratio of the pre-product, the ethanol-water mixed solution, and the compound is 0.04-0.08 mol:150 mL:0.03-0.06 mol, and the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:1;

[0017] Finally, the silanol group after hydrolysis of the pre-product is reacted with the amino group of the compound to generate a modified flame retardant.

[0018] The heat-resistant modifier is prepared by the following method:

[0019] Step B1: maleic anhydride was placed in a flask, sealed, and ammonia gas was introduced. When the flask was cooled to room temperature, the ammonia gas was stopped, and the temperature was raised to 180°C for reaction for 6 hours. After cooling to room temperature, tetrahydrofuran, formaldehyde, and sodium hydroxide were added and mixed evenly. The mixture was reacted at 30°C for 4 hours, rotary evaporated, washed, centrifuged, and dried at 45°C for 24 hours. The temperature was then adjusted to 15°C, and triethylamine, toluene, and diphenylphosphine chloride were added dropwise. After the addition was complete, the temperature was slowly raised to 80°C, kept at this temperature for reaction for 3 hours, cooled, and dried to obtain an intermediate.

[0020] Furthermore, the usage ratio of maleic anhydride, tetrahydrofuran, formaldehyde, sodium hydroxide, triethylamine, toluene, and diphenylphosphine chloride is 0.164-0.328 g: 3.27-3.63 g: 0.05-0.1 g: 0.25-0.32 mL: 4.5 g: 50 g: 0.53-1.06 g;

[0021] First, ammonia is introduced to imide maleic anhydride, then formaldehyde is added to hydroxymethylate it, and then it reacts with the chlorine atom of diphenylphosphine chloride to form an intermediate;

[0022] Step B2: Mix 4-hydroxyanisylsulfone, acryloyl chloride and tetrabutylammonium bromide, stir for 20 minutes, heat to 80°C and react for 1 hour, cool to room temperature, wash, rotary evaporate, and dry at 60°C to obtain the intermediate product;

[0023] Furthermore, the mass ratio of 4-hydroxyanisylsulfone, acryloyl chloride and tetrabutylammonium bromide is 0.86-1.72 g: 0.45-0.9 g: 0.001 g;

[0024] Secondly, the hydroxyl group of 4-hydroxyphenyl sulfone reacts with the acyl chloride of acryloyl chloride to generate an intermediate product;

[0025] Step B3: The intermediate and benzoyl peroxide are evenly dispersed in xylene, and the intermediate product is added and stirred evenly. Under nitrogen protection, the mixture is heated to 90° C. and reacted for 4.5 hours. The mixture is then distilled under reduced pressure, cooled, washed, filtered, and vacuum dried to obtain a heat-resistant modifier.

[0026] Furthermore, the usage ratio of the intermediate, benzoyl peroxide, xylene, and intermediate product is 0.01-0.02 mol: 0.16 g: 70 mL: 0.01-0.02 mol;

[0027] Finally, the carbon-carbon double bonds of the intermediate and the intermediate product are copolymerized to generate a heat-resistant modifier.

[0028] A method for preparing a fiber-reinforced flame-retardant plastic comprises the following steps:

[0029] S1. Fully mixing polycarbonate, titanium dioxide, heat-resistant modifier, modified flame retardant and lubricant in a mixer to prepare a premixed material;

[0030] S2. The premixed material is added to a twin-screw extruder granulator for melting at a processing temperature of 200-280°C and a screw speed of 350-380 r / min. Glass fiber is then added and extruded and pelletized into uniform pellets through the twin-screw extruder granulator to obtain fiber-reinforced flame-retardant plastic.

[0031] Beneficial effects of the present invention:

[0032] The fiber-reinforced flame-retardant plastic of the present invention not only has good flame retardancy and high-temperature resistance, effectively extending the service life of the material, but also has excellent toughening effect and reduces brittleness.

[0033] The compound containing piperazine pyrophosphate in the modified flame retardant prepared by the present invention effectively acts as a carbon source in polycarbonate plastic, synergistically acts with the phosphorus-nitrogen flame retardant to form an expanded carbon layer, effectively blocks oxygen and fire sources, and achieves synergistic flame retardancy. During combustion, the nitrogen element is converted into an inert gas, diluting oxygen and combustible gases and reducing combustion intensity. At the same time, the phosphorus element in dimethyl chlorophosphate forms a phosphate protective layer to inhibit flame spread, thereby achieving a flame retardant effect. In addition, the phosphorus-nitrogen flame retardant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide in the preproduct, as a phosphaphenanthrene compound with high thermal stability, can effectively flame retard in the condensed phase and gas phase, promote the formation of a dense and continuous carbon layer, isolate oxygen and heat exchange, and further enhance the flame retardant effect. In addition, the flame retardant prepared by the present invention is halogen-free, helps reduce environmental pollution and damage to the ecosystem, is harmless to human health, and achieves sustainable development.

[0034] The heat-resistant modifier prepared by the present invention has an intermediate maleimide group with a dipole moment perpendicular to the main axis of the molecular chain, which effectively enhances the interaction between molecules, significantly improves the glass transition temperature and melting point of the material, increases the heat resistance, effectively prevents the material from embrittlement in a high-temperature environment, and prolongs the service life. At the same time, due to the flexibility of the group, the flexibility of the plastic molecular chain is enhanced, an interpenetrating network structure is constructed, stress concentration is relieved, and the toughness of the material is improved. In addition, the intermediate phosphite compound can decompose hydroperoxides, prevent free radical oxidation, and improve the stability of the plastic. Through its strong redox property, it inhibits yellowing at high temperature and maintains the good appearance of the plastic. The sulfone group of the intermediate product, as a powerful electron-withdrawing group, can reduce the electron cloud density of the connected carbon atoms, enhance the molecular thermal stability, further restrict the movement of the molecular chain through chain extension, and improve the heat resistance. In addition, the heat-resistant modifier is compatible with polycarbonate and effectively prevents migration. DETAILED DESCRIPTION

[0035] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0036] Example 1: A method for preparing a fiber-reinforced flame-retardant plastic, comprising the following steps:

[0037] S1. Weigh the raw materials by weight: 60 parts of polycarbonate, 20 parts of titanium dioxide, 20 parts of glass fiber, 2 parts of a heat-resistant modifier (prepared in this example), 0.1 parts of a modified flame retardant (prepared in this example), and 1 part of a lubricant; fully mix the polycarbonate, titanium dioxide, heat-resistant modifier, modified flame retardant, and pentaerythritol stearate in a mixer to prepare a premixed material;

[0038] S2, adding the premixed material to a twin-screw extruder granulator for melting, with a processing temperature of 200°C and a screw speed of 350 r / min, then adding glass fiber, extruding and pelletizing into uniform pellets through the twin-screw extruder granulator, and obtaining a fiber-reinforced flame-retardant plastic;

[0039] The modified flame retardant is prepared by the following method:

[0040] Step A1: 5.3 g of anhydrous sodium carbonate and 20 mL of deionized water were stirred evenly, and the mixture was heated to 80°C. Then, 2.15 g of anhydrous piperazine and 7.47 g of dimethyl chlorophosphate were added and mixed. The mixture was reacted for 8 h, allowed to stand, filtered, washed, and dried in vacuo. Under a nitrogen atmosphere, 7.41 g of 1,3-propylenediamine was added. The mixture was stirred at 100°C for 30 min, refluxed at 140°C for 8 h, and rotary evaporated to obtain the compound;

[0041] Step A2: 0.04 mol of 3-butylenetriethoxysilane and 100 mL of ethanol were mixed, stirred at 80° C. for 10 h, and then 0.04 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, stirred for 12 h, cooled to room temperature, filtered, and washed to obtain a pre-product;

[0042] Step A3: 0.04 mol of the pre-product and 150 mL of an ethanol-water mixed solution were mixed at 35° C. for 10 minutes, and then 0.03 mol of the compound was added. The mixture was reacted at 100° C. for 5 hours, and then heating was stopped. The mixture was naturally cooled to room temperature while stirring, filtered, washed, and dried to obtain a modified flame retardant. The volume ratio of ethanol to water in the ethanol-water mixed solution was 4:1.

[0043] The heat-resistant modifier is prepared by the following method:

[0044] Step B1: 0.164 g of maleic anhydride was placed in a flask, which was sealed and ammonia gas was introduced. When the flask was cooled to room temperature, the ammonia gas was stopped and the temperature was raised to 180° C. for reaction for 6 h. After cooling to room temperature, 3.27 g of tetrahydrofuran, 0.05 g of formaldehyde and 0.25 mL of sodium hydroxide were added and mixed evenly. The mixture was reacted at 30° C. for 4 h, rotary evaporated, washed, centrifuged, and dried at 45° C. for 24 h. The temperature was then adjusted to 15° C., 4.5 g of triethylamine, 50 g of toluene and 0.53 g of diphenylphosphine chloride were added dropwise. After the addition was complete, the temperature was slowly raised to 80° C., the mixture was kept at this temperature for reaction for 3 h, cooled and dried to obtain an intermediate.

[0045] Step B2: Mix 0.86 g of 4-hydroxyanisylsulfone, 0.45 g of acryloyl chloride, and 0.001 g of tetrabutylammonium bromide, stir for 20 min, heat to 80°C, react for 1 h, cool to room temperature, wash, rotary evaporate, and dry at 60°C to obtain the intermediate product;

[0046] Step B3: Disperse 0.01 mol of the intermediate and 0.16 g of benzoyl peroxide in 70 mL of xylene, then add 0.01 mol of the intermediate product and stir evenly. Under nitrogen protection, heat to 90°C and react for 4.5 hours. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain a heat-resistant modifier.

[0047] Example 2: A method for preparing a fiber-reinforced flame-retardant plastic, comprising the following steps:

[0048] S1. Weigh the raw materials by weight: 70 parts of polycarbonate, 25 parts of titanium dioxide, 25 parts of glass fiber, 6 parts of heat-resistant modifier (prepared in this example), 1 part of modified flame retardant (prepared in this example), and 2 parts of lubricant; fully mix the polycarbonate, titanium dioxide, heat-resistant modifier, modified flame retardant, and pentaerythritol stearate in a mixer to prepare a premixed material;

[0049] S2, adding the premixed material to a twin-screw extruder granulator for melting, with a processing temperature of 240°C and a screw speed of 365 r / min, then adding glass fiber, extruding through the twin-screw extruder granulator, and pelletizing into uniform pellets to obtain a fiber-reinforced flame-retardant plastic;

[0050] The modified flame retardant is prepared by the following method:

[0051] Step A1: 7.95 g of anhydrous sodium carbonate and 35 mL of deionized water were stirred evenly, and the mixture was heated to 80°C. Then, 3.225 g of anhydrous piperazine and 12.7 g of dimethyl chlorophosphate were added and mixed. The mixture was reacted for 8 h, allowed to stand, filtered, washed, and dried in vacuo. Under a nitrogen atmosphere, 11.12 g of 1,3-propylenediamine was added, and the mixture was stirred at 100°C for 30 min. The mixture was condensed and refluxed at 140°C for 8 h, and rotary evaporated to obtain the compound;

[0052] Step A2: 0.06 mol of 3-butylenetriethoxysilane and 150 mL of ethanol were mixed, stirred at 80° C. for 10 h, and then 0.06 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, stirred for 12 h, cooled to room temperature, filtered, and washed to obtain a pre-product;

[0053] Step A3: 0.06 mol of the pre-product and 150 mL of an ethanol-water mixed solution were mixed at 35°C for 10 minutes, and then 0.045 mol of the compound was added. The mixture was reacted at 100°C for 5 hours, and then heating was stopped. The mixture was naturally cooled to room temperature while stirring, filtered, washed, and dried to obtain a modified flame retardant. The volume ratio of ethanol to water in the ethanol-water mixed solution was 4:1.

[0054] The heat-resistant modifier is prepared by the following method:

[0055] Step B1: 0.246 g of maleic anhydride was placed in a flask, which was sealed and ammonia gas was introduced. When the flask was cooled to room temperature, the ammonia gas was stopped and the temperature was raised to 180°C for reaction for 6 h. After cooling to room temperature, 3.45 g of tetrahydrofuran, 0.075 g of formaldehyde and 0.285 mL of sodium hydroxide were added and mixed evenly. The mixture was reacted at 30°C for 4 h, rotary evaporated, washed, centrifuged, and dried at 45°C for 24 h. The temperature was then adjusted to 15°C, and 4.5 g of triethylamine, 50 g of toluene and 0.795 g of diphenylphosphine chloride were added dropwise. After the addition was complete, the temperature was slowly raised to 80°C, kept for reaction for 3 h, cooled and dried to obtain an intermediate.

[0056] Step B2: Mix 1.29 g of 4-hydroxyanisylsulfone, 0.675 g of acryloyl chloride, and 0.001 g of tetrabutylammonium bromide, stir for 20 min, heat to 80°C, react for 1 h, cool to room temperature, wash, rotary evaporate, and dry at 60°C to obtain the intermediate product;

[0057] Step B3: Disperse 0.015 mol of the intermediate and 0.16 g of benzoyl peroxide in 70 mL of xylene, then add 0.015 mol of the intermediate product and stir evenly. Under nitrogen protection, heat to 90°C and react for 4.5 hours. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain a heat-resistant modifier.

[0058] Example 3: A method for preparing a fiber-reinforced flame-retardant plastic, comprising the following steps:

[0059] S1. Weighing raw materials by weight: 80 parts of polycarbonate, 30 parts of titanium dioxide, 30 parts of glass fiber, 8 parts of heat-resistant modifier (prepared in this example), 2 parts of modified flame retardant (prepared in this example), and 3 parts of lubricant; fully mixing the polycarbonate, titanium dioxide, heat-resistant modifier, modified flame retardant, and pentaerythritol stearate in a mixer to prepare a premixed material;

[0060] S2, adding the premixed material to a twin-screw extruder granulator for melting, with a processing temperature of 280°C and a screw speed of 380 r / min, then adding glass fiber, extruding through the twin-screw extruder granulator, and pelletizing into uniform pellets to obtain a fiber-reinforced flame-retardant plastic;

[0061] The modified flame retardant is prepared by the following method:

[0062] Step A1: 10.6 g of anhydrous sodium carbonate and 50 mL of deionized water were stirred evenly, and the mixture was heated to 80°C. Then, 4.3 g of anhydrous piperazine and 14.94 g of dimethyl chlorophosphate were added and mixed. The mixture was reacted for 8 h, allowed to stand, filtered, washed, and dried in vacuo. Under a nitrogen atmosphere, 14.82 g of 1,3-propylenediamine was added, and the mixture was stirred at 100°C for 30 min. The mixture was condensed and refluxed at 140°C for 8 h, and rotary evaporated to obtain the compound;

[0063] Step A2: 0.08 mol of 3-butylenetriethoxysilane and 200 mL of ethanol were mixed, stirred at 80° C. for 10 h, and then 0.08 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, stirred for 12 h, cooled to room temperature, filtered, and washed to obtain a pre-product;

[0064] Step A3: 0.08 mol of the pre-product and 150 mL of an ethanol-water mixed solution were mixed at 35°C for 10 minutes, and then 0.06 mol of the compound was added. The mixture was reacted at 100°C for 5 hours, and then heating was stopped. The mixture was naturally cooled to room temperature while stirring, filtered, washed, and dried to obtain a modified flame retardant. The volume ratio of ethanol to water in the ethanol-water mixed solution was 4:1.

[0065] The heat-resistant modifier is prepared by the following method:

[0066] Step B1: 0.328 g of maleic anhydride was placed in a flask, which was sealed and then introduced with ammonia gas. When the flask was cooled to room temperature, the ammonia gas was stopped, and the temperature was raised to 180° C. for reaction for 6 h. After cooling to room temperature, 3.63 g of tetrahydrofuran, 0.1 g of formaldehyde and 0.32 mL of sodium hydroxide were added and mixed evenly. The mixture was reacted at 30° C. for 4 h, rotary evaporated, washed, centrifuged, and dried at 45° C. for 24 h. The temperature was then adjusted to 15° C., 4.5 g of triethylamine, 50 g of toluene and 1.06 g of diphenylphosphine chloride were added dropwise. After the addition was complete, the temperature was slowly raised to 80° C., the mixture was kept at this temperature for reaction for 3 h, cooled, and dried to obtain an intermediate.

[0067] Step B2: Mix 1.72 g of 4-hydroxyanisylsulfone, 0.9 g of acryloyl chloride, and 0.001 g of tetrabutylammonium bromide, stir for 20 min, heat to 80°C, react for 1 h, cool to room temperature, wash, rotary evaporate, and dry at 60°C to obtain the intermediate product;

[0068] Step B3: Disperse 0.02 mol of the intermediate and 0.16 g of benzoyl peroxide in 70 mL of xylene, then add 0.02 mol of the intermediate product and stir evenly. Under nitrogen protection, heat to 90°C and react for 4.5 hours. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain a heat-resistant modifier.

[0069] Comparative Example 1: This comparative example is a fiber-reinforced flame-retardant plastic. The difference from Example 3 is that an equal amount of magnesium hydroxide is used instead of the modified flame retardant prepared in Example 3, and the rest are the same.

[0070] Comparative Example 2: This comparative example is a fiber-reinforced flame-retardant plastic. The difference from Example 3 is that an equal amount of dibutyltin dilaurate is used instead of the heat-resistant modifier prepared in Example 3. The rest are the same.

[0071] Performance Testing: The fiber-reinforced flame-retardant plastics prepared in Examples 1-3 and Comparative Examples 1-2 were cut into standard test sizes and tested for vertical burning performance using the GB / T 2048-1996 Plastics Burning Performance Test Method; the heat deformation temperature was tested according to the GB / T 1634.2-2004 standard; the glass transition temperature was tested according to the GB / T 19466.2-2004 standard; and the flexural strength was tested using the GB1042-79 standard. The test results are shown in Table 1 below:

[0072] Table 1

[0073]

[0074] From the test data in Table 1, it can be seen that the fiber-reinforced flame-retardant plastic prepared by the present invention has excellent flame retardant and high temperature resistance effects. It can also be seen from the above table that the fiber-reinforced flame-retardant plastic prepared by the present invention has good toughening performance.

[0075] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a fiber-reinforced flame-retardant plastic, characterized in that: The specific steps include: S1. Weigh the raw materials by weight: 60-80 parts of polycarbonate, 20-30 parts of titanium dioxide, 20-30 parts of glass fiber, 2-8 parts of heat-resistant modifier, 0.1-2 parts of modified flame retardant, and 1-3 parts of lubricant; fully mix the polycarbonate, titanium dioxide, heat-resistant modifier, modified flame retardant, and lubricant in a mixer to prepare a premixed material; S2, adding the premixed material to a twin-screw extruder granulator for melting, with a processing temperature of 200-280°C and a screw speed of 350-380 r / min, then adding glass fiber, extruding and pelletizing into uniform particles through the twin-screw extruder granulator, and obtaining a fiber-reinforced flame-retardant plastic; The modified flame retardant is prepared by the following method: Step A1: Anhydrous sodium carbonate and deionized water were stirred evenly, heated to 80°C, and then anhydrous piperazine and dimethyl chlorophosphate were added and mixed, reacted for 8 hours, allowed to stand, filtered, washed, and dried in vacuo. Under a nitrogen environment, 1,3-propylenediamine was added, stirred at 100°C for 30 minutes, condensed and refluxed at 140°C for 8 hours, and rotary evaporated to obtain a compound. The dosage ratio of anhydrous sodium carbonate, deionized water, anhydrous piperazine, dimethyl chlorophosphate, and 1,3-propylenediamine was 5.3-10.6 g: 20-50 mL: 2.15-4.3 g: 7.47-14.94 g: 7.41-14.82 g; Step A2: 3-Butenetriethoxysilane and ethanol were mixed, stirred at 80° C. for 10 h, and then 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide was added, stirred for 12 h, cooled to room temperature, filtered, and washed to obtain a pre-product; Step A3: After mixing the pre-product and the ethanol-water mixed solution at 35° C. for 10 minutes, the compound is added, and the mixture is reacted at 100° C. for 5 hours. The heating is stopped, and the mixture is naturally cooled to room temperature while stirring, filtered, washed, and dried to obtain a modified flame retardant; The heat-resistant modifier is prepared by the following method: Step B1: maleic anhydride was placed in a flask, sealed, and ammonia gas was introduced. When the flask was cooled to room temperature, the ammonia gas was stopped, and the temperature was raised to 180°C for reaction for 6 hours. After cooling to room temperature, tetrahydrofuran, formaldehyde, and sodium hydroxide were added and mixed evenly. The mixture was reacted at 30°C for 4 hours, rotary evaporated, washed, centrifuged, and dried at 45°C for 24 hours. The temperature was then adjusted to 15°C, and triethylamine, toluene, and diphenylphosphine chloride were added dropwise. After the addition was complete, the temperature was slowly raised to 80°C, kept at this temperature for reaction for 3 hours, cooled, and dried to obtain an intermediate. Step B2: Mix 4-hydroxyanisylsulfone, acryloyl chloride and tetrabutylammonium bromide, stir for 20 minutes, heat to 80°C and react for 1 hour, cool to room temperature, wash, rotary evaporate, and dry at 60°C to obtain the intermediate product; Step B3: Disperse the intermediate and benzoyl peroxide evenly in xylene, then add the intermediate product and stir evenly. Under nitrogen protection, heat to 90°C and react for 4.5 hours. Distill under reduced pressure, cool, wash, filter, and vacuum dry to obtain a heat-resistant modifier.

2. The method for preparing a fiber-reinforced flame-retardant plastic according to claim 1, characterized in that: In step A2, the usage ratio of 3-butenetriethoxysilane, ethanol, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is 0.04-0.08 mol: 100-200 mL: 0.04-0.08 mol.

3. The method for preparing a fiber-reinforced flame-retardant plastic according to claim 1, characterized in that: In step A3, the ratio of the pre-product, ethanol-water mixed solution, and compound is 0.04-0.08 mol:150 mL:0.03-0.06 mol, and the volume ratio of ethanol to water in the ethanol-water mixed solution is 4:

1.

4. The method for preparing a fiber-reinforced flame-retardant plastic according to claim 1, characterized in that: In step B1, the usage ratio of maleic anhydride, tetrahydrofuran, formaldehyde, sodium hydroxide, triethylamine, toluene, and diphenylphosphine chloride is 0.164-0.328 g: 3.27-3.63 g: 0.05-0.1 g: 0.25-0.32 mL: 4.5 g: 50 g: 0.53-1.06 g.

5. The method for preparing a fiber-reinforced flame-retardant plastic according to claim 1, characterized in that: The mass ratio of 4-hydroxyanisylsulfone, acryloyl chloride and tetrabutylammonium bromide in step B2 is 0.86-1.72 g: 0.45-0.9 g: 0.001 g.

6. The method for preparing a fiber-reinforced flame-retardant plastic according to claim 1, characterized in that: The usage ratio of the intermediate, benzoyl peroxide, xylene, and intermediate product in step B3 is 0.01-0.02 mol: 0.16 g: 70 mL: 0.01-0.02 mol.

7. The method for preparing a fiber-reinforced flame-retardant plastic according to claim 1, characterized in that: The lubricant is pentaerythritol stearate.

8. A fiber-reinforced flame-retardant plastic, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 7.

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