Low-smoke halogen-free environment-friendly flame retardant

Abstract

The invention discloses a low-smoke halogen-free environment-friendly flame retardant, and relates to the technical field of flame retardants. The invention discloses a low-smoke halogen-free environment-friendly flame retardant. The graphene quantum dot composite material is prepared from the following raw materials in parts by weight: 8 to 12 parts of novel phosphorus-nitrogen heterocyclic compound, 5 to 9 parts of silane-terminated polyether, 2 to 5 parts of graphene quantum dot dispersion liquid, 6 to 10 parts of pentaerythritol diphosphate melamine salt, 5 to 8 parts of melamine cyanurate, 3 to 6 parts of zinc borate, 8 to 12 parts of magnesium hydroxide, 10 to 15 parts of ammonium polyphosphate, 3 to 7 parts of modified polycarbonate and 4 to 8 parts of aluminum diethylphosphinate. The invention relates to a high-temperature-resistant anti-aging coating which is prepared from the following components in parts by weight: 2-4 parts of an organic silicon elastomer, 0.2-0.5 part of triphenyl phosphate, 0.3-0.6 part of polyethylene wax, 0.3-0.8 part of a silane coupling agent KH-550 and 25-35 parts of deionized water. The low-smoke halogen-free environment-friendly flame retardant disclosed by the invention has remarkable advantages, adopts various environment-friendly raw materials, and is green, safe and free of halogen pollution. Through the unique formula design, all the components have a synergistic effect, the flame retardant property is excellent, and the fire risk can be effectively reduced. The added graphene quantum dots and other components also improve the thermal stability and mechanical properties of the product, and the application prospect is wide.

Description

Technical Field

[0001] The present invention relates to the technical field of flame retardants, in particular to a low-smoke, halogen-free and environmentally friendly flame retardant. Background Art

[0002] As modern society continues to progress, fire safety and environmental protection have become crucial issues, and people's demands on both aspects are becoming increasingly stringent. Flame retardants play an indispensable role in many key areas, such as construction, electronics, and transportation. However, while traditional halogenated flame retardants provide flame retardant benefits, they also conceal significant hidden dangers. When a fire occurs, the combustion of halogenated flame retardants releases large amounts of toxic and harmful gases, such as hydrogen halides. These gases are not only highly irritating and can cause serious damage to the human respiratory tract, eyes, and other organs, but they also severely pollute the environment and cause long-term damage to ecosystems. As a result, the use of traditional halogenated flame retardants has gradually been restricted, and halogen-free flame retardants have become a hot research topic among researchers.

[0003] Although existing halogen-free flame retardants meet the basic requirements of environmental protection, there are still many problems that are difficult to ignore. First of all, low flame retardant efficiency is a major pain point. When faced with high-temperature open flames, many halogen-free flame retardants are unable to quickly and effectively suppress the spread of flames, making it difficult to provide reliable safety guarantees. Secondly, poor thermal stability is also a common problem. Under high temperature conditions, the chemical structure of the halogen-free flame retardant itself is prone to change, resulting in a significant decrease in its flame retardant performance. Furthermore, in order to achieve a certain flame retardant level, it is often necessary to add a large amount of halogen-free flame retardant, which in turn will have an adverse effect on the original mechanical properties and processing properties of the material, such as making the material brittle, reducing flexibility, and causing difficulties in molding during processing.

[0004] For example, electronic devices are becoming increasingly miniaturized and integrated, with increasingly compact internal spaces. This requires flame retardants to possess not only excellent flame retardancy but also exceptional thermal stability and compatibility to ensure long-term stable operation in high-temperature, confined spaces without damaging electronic components. Conventional halogen-free flame retardants simply cannot meet these stringent requirements. In buildings, where densely populated areas are difficult to evacuate, flame retardants must not only effectively prevent the spread of fire but also exhibit low smoke and toxicity properties to ensure safe evacuation and minimize casualties.

[0005] In summary, the market urgently needs a low-smoke, halogen-free, environmentally friendly flame retardant with excellent comprehensive performance. It must not only achieve high flame retardancy, but also meet strict environmental standards, while also not negatively impacting the mechanical and processing properties of materials. This invention was developed precisely in response to this market gap, dedicated to filling this market gap and providing strong support for fire safety and sustainable development in various fields. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the present invention provides a low-smoke, halogen-free, and environmentally friendly flame retardant to solve the above problems.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions: A low-smoke, halogen-free, environmentally friendly flame retardant comprises the following raw materials in parts by weight: 8-12 parts of a novel phosphorus-nitrogen heterocyclic compound, 5-9 parts of a silane-terminated polyether, 2-5 parts of a graphene quantum dot dispersion, 6-10 parts of pentaerythritol diphosphate melamine salt, 5-8 parts of melamine cyanurate, 3-6 parts of zinc borate, 8-12 parts of magnesium hydroxide, 10-15 parts of ammonium polyphosphate, 3-7 parts of modified polycarbonate, 4-8 parts of aluminum diethylphosphinate, 2-4 parts of an organosilicon elastomer, 0.2-0.5 parts of triphenyl phosphite, 0.3-0.6 parts of polyethylene wax, 0.3-0.8 parts of a silane coupling agent KH-550, and 25-35 parts of deionized water.

[0008] Furthermore, the modified polycarbonate is specifically prepared by the following steps: A1. Slowly add dry polycarbonate to a reactor filled with toluene, heat to 60°C and stir until completely dissolved. Stop heating, wait for the solution to cool to room temperature, then add maleic anhydride and furan in sequence, and stir at an accelerated rate for 30 minutes. Raise the temperature of the reactor to 100°C and stir for 6 hours. After the reaction is complete, stop heating, cool naturally to room temperature, pour the reaction solution into methanol for precipitation while stirring, filter, wash, and dry to obtain a polycarbonate containing furan rings. A2, after grinding the product of A1, add it into a quartz glass container filled with anhydrous ethanol, heat it to 40 ° C and stir until it dissolves, pass high-purity nitrogen into the reaction container, add mercaptopropyltrimethoxysilane and benzoin dimethyl ether to the solution in sequence under light-proof conditions, and stir at an increased speed for 30 minutes; keep the nitrogen flow, irradiate the reaction solution with ultraviolet light and stir; after the reaction is completed, stop the illumination and nitrogen flow, pour the reaction solution into deionized water for precipitation, stir while pouring, filter, wash, and dry to obtain a thiol-ene modified polycarbonate; A3. Add 2,2-dihydroxymethylpropionic acid and toluene into a four-necked flask, heat to 80°C and stir to dissolve, then add p-toluenesulfonic acid and hydroquinone, stir evenly, add glycidyl acrylate dropwise, and after the addition is complete, heat to 110°C and react for 4 hours to obtain monomer 1; introduce nitrogen into another reactor, then add N,N-dimethylformamide, then add A2 product and monomer 1, heat and stir to dissolve, then add dibutyltin dilaurate, speed up the stirring reaction for 30 minutes, heat the reactor to 120°C, and stir the reaction for 6 hours; after the reaction is completed, stop heating, let the reactor cool naturally to room temperature, pour the reaction solution into methanol for precipitation, filter the precipitate, collect the solid product, wash and dry to obtain a hyperbranched polymer grafted polycarbonate.

[0009] Furthermore, in step A1, the amount ratio of polycarbonate, toluene, maleic anhydride, and furan is 10 g:50 mL:5 g:3 g; the initial stirring speed is 200 r / min, and the speed after acceleration is 400 r / min; the reactor heating rate is 5°C / min; the precipitate is washed with methanol and then dried in a vacuum drying oven at 70°C for 24 hours.

[0010] Furthermore, in the A2 step, the amount ratio of A1 product, anhydrous ethanol, mercaptopropyl trimethoxysilane, and benzoin dimethyl ether is 8g:40mL:4g:0.5g; the A product is ground through an 80-mesh sieve and stirred at a speed of 300r / min, and the speed is increased to 600r / min; the flow rate of nitrogen is 100mL / min, and the flow time is 15min; the wavelength is 365nm, 10mW / cm 2 The product was irradiated with strong ultraviolet light for 3 h; after filtering, it was washed with deionized water and then dried in a vacuum drying oven at 50°C for 24 h.

[0011] Furthermore, in step A3, the amount ratio of 2,2-dihydroxymethylpropionic acid, glycidyl acrylate, p-toluenesulfonic acid, hydroquinone, and toluene is 10g:11g:0.5g:0.4g:50mL; the amount ratio of N,N-dimethylformamide, A2 product, monomer 1, and dibutyltin dilaurate is 40mL:6g:5g:0.3g; the initial stirring speed is 400r / min, and the speed after speed increase is 600r / min; the nitrogen flow rate is 100mL / min, and the introduction time is 15min; the reactor heating rate is 5°C / min; the product after filtration is washed with methanol, and then dried in a vacuum drying oven at 80°C for 24h.

[0012] In step A1, a Diels-Alder reaction occurs, with maleic anhydride acting as a dienophile and furan as a diene, and the two undergo a [4+2] cycloaddition reaction, introducing a furan ring into the polycarbonate molecular chain. This changes the structure of the polycarbonate, provides active sites for subsequent reactions, and may enhance intermolecular interactions and improve the performance of the material.

[0013] Benzoin dimethyl ether acts as a photoinitiator, generating free radicals under UV light. The mercapto group in mercaptopropyltrimethoxysilane undergoes a thiol-ene click reaction with the carbon-carbon double bond in the A1 product molecule, grafting mercaptopropyltrimethoxysilane onto the polycarbonate molecular chain, further altering the structure and properties of the polycarbonate. The introduced siloxane groups enhance the material's water resistance, flexibility, and interfacial compatibility.

[0014] The carboxyl group of 2,2-dimethylolpropionic acid undergoes a ring-opening esterification reaction with the epoxy group of glycidyl acrylate to produce Monomer 1, which contains a double bond and a hydroxyl group. The double bond in Product A2 undergoes free radical polymerization with the double bond of Monomer 1. Simultaneously, the hydroxyl group of Monomer 1 reacts with reactive groups on other monomers or Product A2 to form a hyperbranched structure that is grafted onto the polycarbonate, improving the material's thermal stability, mechanical properties, and flame retardancy.

[0015] Furthermore, the graphene quantum dot dispersion is specifically prepared in the following steps: B1. Add concentrated sulfuric acid and concentrated nitric acid to a three-necked flask and stir in an ice bath. While stirring, add graphite powder to the mixed acid and stir for 15 minutes. Then, add potassium permanganate dropwise. After the addition is complete, continue stirring for 1.5 hours. Heat the system to 40°C and continue the reaction for 4 hours. B2. After the reaction is completed, heating is stopped, the reaction solution is cooled to room temperature, hydrogen peroxide is added until the reaction solution has no bubbles, the reaction solution is transferred to a centrifuge tube and centrifuged, the supernatant is poured out, and the precipitate is washed with hydrochloric acid solution. After the reaction solution is centrifuged, the collected precipitate is washed with deionized water, and finally, the washed graphene oxide is dried to obtain graphene oxide solid; B3. Add graphene oxide to deionized water, ultrasonically disperse for 1 hour, and then hydrothermally react at 200°C for 10 hours. After the reaction is completed, cool to room temperature to obtain a graphene quantum dot dispersion; add ammonia water to adjust the pH value of the dispersion to 10, then add silane coupling agent KH-560 to the dispersion and continue to stir evenly; place the reaction vessel in a constant temperature water bath at 70°C and stir the reaction for 4 hours; after the reaction is completed, transfer the reaction solution to a dialysis bag and dialyze with deionized water for 5 days, changing the dialysate 3 times a day to obtain a surface-modified graphene quantum dot dispersion.

[0016] Concentrated sulfuric acid and nitric acid provide a highly acidic environment, while potassium permanganate acts as a strong oxidant, causing the graphite powder to undergo an oxidation reaction. During this reaction, oxygen-containing functional groups, such as hydroxyl and carboxyl groups, are inserted between the graphite layers, increasing the interlayer spacing and forming graphene oxide. This alters the structure and properties of the graphite, creating conditions for the subsequent preparation of graphene quantum dots.

[0017] Under the hydrothermal environment, the graphene oxide sheets undergo fracture, recombination, and reduction reactions under high temperature and pressure. Some oxygen-containing functional groups are removed, and the sheet size is reduced, forming graphene quantum dots. After the reaction is completed, the solution is cooled to room temperature to obtain a graphene quantum dot dispersion. Under alkaline conditions, the siloxane groups of the silane coupling agent KH-560 hydrolyze to form silanol groups. These silanol groups react with the hydroxyl groups on the surface of the graphene quantum dots, grafting silane coupling agent molecules onto the graphene quantum dots. This results in surface modification, improving the dispersibility of the graphene quantum dots in the polymer matrix and their compatibility with other components.

[0018] Furthermore, in step B1, the ratio of concentrated sulfuric acid, concentrated nitric acid, graphite powder, and potassium permanganate is 30 mL: 10 mL: 5 g: 7 g; the stirring speed is 300 r / min; in step B2, the centrifugal speed is 2000 r / min, each centrifugation is 15 minutes, the supernatant is discarded, and the precipitate is washed three times with 5% hydrochloric acid solution, and the remaining reaction solution is added and this operation is repeated; after the reaction solution is centrifuged, the collected precipitate is washed with deionized water until neutral, and the precipitate is dried in a vacuum drying oven at 70°C for 12 hours.

[0019] Furthermore, in step B3, the usage ratio of graphene oxide, deionized water, and silane coupling agent KH-560 is 1 g:100 mL:3 g; and the stirring speed is 400 r / min.

[0020] A method for preparing a low-smoke, halogen-free, environmentally friendly flame retardant comprises the following steps: S1. Add zinc borate and magnesium hydroxide to a high-speed mixer and stir for 5 minutes. Then add pentaerythritol diphosphate melamine salt, melamine cyanurate, ammonium polyphosphate and aluminum diethylphosphinate, and stir at an increased speed for 5 minutes. Then add the novel phosphorus-nitrogen heterocyclic compound, silane-terminated polyether and graphene quantum dot dispersion, and stir at a maintained speed for 5 minutes. Finally, add triphenyl phosphite, polyethylene wax and silane coupling agent KH-550, and stir at an increased speed for 10 minutes. S2. Add modified polycarbonate and silicone elastomer to the pre-dispersed mixture, continue stirring for 20 minutes, then slowly add deionized water and stir for 15 minutes to form a uniform slurry; S3. Preheat the drying tower of the spray granulator, and form the slurry into granules through spray granulation; dry the granulated flame retardant particles in an oven at 80° C. for 12 hours to obtain a low-smoke halogen-free and environmentally friendly flame retardant.

[0021] Furthermore, in the step S1, the initial stirring speed is 1000 r / min, the stirring speed after accelerating is 1200 r / min, and the stirring speed after adding the additive to increase the speed is 1500 r / min; in the step S2, the stirring speed is 2000 r / min; in the step S3, the drying tower is preheated to 150°C, the feed rate is 8 L / h, the spray pressure is 0.5 MPa, the atomizer speed is 12000 r / min, and the hot air temperature is 150°C.

[0022] The present invention provides a low-smoke, halogen-free, environmentally friendly flame retardant, which has the following beneficial effects: 1. Highly Efficient Flame Retardancy: The flame retardant of this invention contains multiple flame-retardant ingredients, such as pentaerythritol diphosphate melamine salt and ammonium polyphosphate. These decompose upon heating to produce phosphoric acid and metaphosphoric acid. These substances form a dense carbonized layer on the surface of the material, isolating it from oxygen and heat and preventing further combustion. Simultaneously, inorganic flame retardants such as zinc borate and magnesium hydroxide decompose at high temperatures, absorbing heat and lowering the surface temperature of the material, thereby inhibiting combustion. The synergistic effect of these multiple flame retardants significantly improves flame retardancy, effectively reducing the likelihood of fire and protecting life and property.

[0023] 2. Low-smoke, halogen-free, and environmentally friendly: This product eliminates traditional halogen-containing flame retardants, preventing the release of toxic gases such as hydrogen halides during combustion, reducing environmental pollution and harm to humans. Furthermore, the amount of smoke produced during combustion is minimal, preventing dense smoke from forming at the fire scene to hinder evacuation and fire rescue efforts, thus buying more time for escape and meeting current environmental and safety requirements.

[0024] 3. Improved Material Performance: Added ingredients such as silane-terminated polyether and silicone elastomer enhance the material's flexibility and mechanical properties, allowing the flame retardant-added material to possess improved impact resistance and tensile strength while maintaining its original functionality. Furthermore, the addition of a graphene quantum dot dispersion improves the material's thermal stability, enhancing its performance in high-temperature environments and broadening its application range.

[0025] 4. Good dispersibility and compatibility: Through the special preparation process of modified polycarbonate and the addition of additives such as silane coupling agent KH-550, the various components have good dispersibility and compatibility. During the preparation process, the raw materials can be evenly mixed to form a stable system without agglomeration or stratification, ensuring the uniform distribution of the flame retardant in the material, thereby ensuring the consistency and stability of the overall material performance. DETAILED DESCRIPTION

[0026] 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 part of the embodiments of the present invention, not all of them. 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.

[0027] Example 1: Preparation of a low-smoke, halogen-free, environmentally friendly flame retardant. The specific preparation steps are as follows: S1, 3 parts of zinc borate and 8 parts of magnesium hydroxide were added to a high-speed mixer and stirred at 1000 r / min for 5 minutes, followed by the addition of 6 parts of pentaerythritol diphosphate melamine salt, 5 parts of melamine cyanurate, 10 parts of ammonium polyphosphate and 4 parts of diethyl aluminum phosphinate, and stirred at 1200 r / min for 5 minutes, followed by the addition of 8 parts of a novel phosphorus-nitrogen heterocyclic compound, 5 parts of a silane-terminated polyether and 2 parts of a graphene quantum dot dispersion, and the mixture was stirred at the same speed for 5 minutes, and finally, 0.2 parts of triphenyl phosphite, 0.3 parts of polyethylene wax and 0.3 parts of a silane coupling agent KH-550 were added and stirred at 1500 r / min for 10 minutes; S2. Add 3 parts of modified polycarbonate and 2 parts of silicone elastomer to the pre-dispersed mixture, stir at a speed of 2000 r / min and continue stirring for 20 minutes, then slowly add 35 parts of deionized water and stir for 15 minutes to form a uniform slurry; S3. Preheat the drying tower of the spray granulator to 150°C, set the feed rate to 8 L / h, the spray pressure to 0.5 MPa, the atomizer speed to 12000 r / min, and the hot air temperature to 150°C, and granulate the slurry by spray granulation; dry the granulated flame retardant particles in an oven at 80°C for 12 hours to obtain a low-smoke halogen-free and environmentally friendly flame retardant.

[0028] Example 2: Preparation of a low-smoke, halogen-free, environmentally friendly flame retardant. The specific preparation steps are as follows: S1, 6 parts of zinc borate and 12 parts of magnesium hydroxide were added to a high-speed mixer and stirred at 1000 r / min for 5 minutes, followed by the addition of 10 parts of pentaerythritol diphosphate melamine salt, 8 parts of melamine cyanurate, 15 parts of ammonium polyphosphate and 8 parts of diethyl aluminum phosphinate, and stirred at 1200 r / min for 5 minutes, followed by the addition of 12 parts of a novel phosphorus-nitrogen heterocyclic compound, 9 parts of a silane-terminated polyether and 5 parts of a graphene quantum dot dispersion, and the mixture was stirred at the same speed for 5 minutes, and finally, 0.5 parts of triphenyl phosphite, 0.6 parts of polyethylene wax and 0.8 parts of a silane coupling agent KH-550 were added and stirred at 1500 r / min for 10 minutes; S2. Add 7 parts of modified polycarbonate and 4 parts of silicone elastomer to the pre-dispersed mixture, stir at a speed of 2000 r / min and continue stirring for 20 minutes, then slowly add 35 parts of deionized water and stir for 15 minutes to form a uniform slurry; S3. Preheat the drying tower of the spray granulator to 150°C, set the feed rate to 8 L / h, the spray pressure to 0.5 MPa, the atomizer speed to 12000 r / min, and the hot air temperature to 150°C, and granulate the slurry by spray granulation; dry the granulated flame retardant particles in an oven at 80°C for 12 hours to obtain a low-smoke halogen-free and environmentally friendly flame retardant.

[0029] Example 3: Preparation of a low-smoke, halogen-free, environmentally friendly flame retardant. The specific preparation steps are as follows: S1. Add 4 parts of zinc borate and 10 parts of magnesium hydroxide to a high-speed stirrer and stir at 1000 r / min for 5 minutes. Then add 8 parts of pentaerythritol diphosphate melamine salt, 6 parts of melamine cyanurate, 12 parts of ammonium polyphosphate and 6 parts of diethyl aluminum phosphinate, stir at 1200 r / min for 5 minutes, then add 10 parts of a novel phosphorus-nitrogen heterocyclic compound, 7 parts of a silane-terminated polyether and 3 parts of a graphene quantum dot dispersion, keep stirring at the speed for 5 minutes, finally add 0.3 parts of triphenyl phosphite, 0.4 parts of polyethylene wax and 0.5 parts of a silane coupling agent KH-550, and stir at 1500 r / min for 10 minutes; S2. Add 5 parts of modified polycarbonate and 3 parts of silicone elastomer to the pre-dispersed mixture, stir at a speed of 2000 r / min and continue stirring for 20 minutes, then slowly add 30 parts of deionized water and stir for 15 minutes to form a uniform slurry; S3. Preheat the drying tower of the spray granulator to 150°C, set the feed rate to 8 L / h, the spray pressure to 0.5 MPa, the atomizer speed to 12000 r / min, and the hot air temperature to 150°C, and granulate the slurry by spray granulation; dry the granulated flame retardant particles in an oven at 80°C for 12 hours to obtain a low-smoke halogen-free and environmentally friendly flame retardant.

[0030] Example 4: Preparation of modified polycarbonate. The specific preparation steps are as follows: A1. Slowly add 10 g of dried polycarbonate to a reactor containing 50 mL of toluene, heat to 60 ° C and stir at 200 r / min until completely dissolved, stop heating, wait for the solution to cool to room temperature, add 5 g of maleic anhydride and 3 g of furan in sequence, and stir at a speed of 400 r / min for 30 min; raise the temperature of the reactor to 100 ° C at a heating rate of 5 ° C / min and stir for 6 h; after the reaction is completed, stop heating, cool naturally to room temperature, pour the reaction solution into methanol for precipitation, stir while pouring, filter, wash the precipitate with methanol, and then dry it in a vacuum drying oven at 70 ° C for 24 h to obtain a polycarbonate containing furan rings; A2, 8g of A1 product was ground and passed through an 80-mesh sieve, and then added to a quartz glass container filled with 40mL of anhydrous ethanol, heated to 40°C and stirred at 300r / min until dissolved, and high-purity nitrogen was introduced into the reaction vessel at a flow rate of 100mL / min for 15min. Under light-proof conditions, 4g of mercaptopropyltrimethoxysilane and 0.5g of benzoin dimethyl ether were added to the solution in sequence, and stirred at 600r / min for 30min; the reaction solution was irradiated with a wavelength of 365nm and 10mW / cm 2 Irradiate with strong ultraviolet light for 3 hours while stirring; after the reaction is completed, stop irradiation and nitrogen flow, pour the reaction solution into deionized water for precipitation, stir while pouring, filter the product, wash it with deionized water, and then dry it in a vacuum drying oven at 50°C for 24 hours; A3, 10g 2,2-dihydroxymethylpropionic acid and 50mL toluene were added to a four-necked flask, heated to 80°C and stirred to dissolve, then 0.5g p-toluenesulfonic acid and 0.4g hydroquinone were added, stirred evenly, 11g glycidyl acrylate was added dropwise, after completion of the addition, the temperature was raised to 110°C and the reaction was carried out for 4 hours to obtain monomer 1; nitrogen was introduced into another reactor at a flow rate of 100mL / min for 15min, and then 40mL N,N-dimethylformamide was added, followed by 6g A2 product The product and 5g of monomer 1 were heated and stirred at 400r / min to dissolve, and then 0.3g of dibutyltin dilaurate was added, and the reaction was stirred at 600r / min for 30min. The reactor was heated to 120°C at a heating rate of 5°C / min, and the reaction was stirred for 6h. After the reaction was completed, the heating was stopped, and the reactor was allowed to cool naturally to room temperature. The reaction solution was poured into methanol for precipitation, the precipitate was filtered, the solid product was collected, washed with methanol, and then dried in a vacuum drying oven at 80°C for 24h to obtain a hyperbranched polymer grafted polycarbonate.

[0031] Example 5: Preparation of graphene quantum dot dispersion. The specific preparation steps are as follows: B1. Add 30 mL of concentrated sulfuric acid and 10 mL of concentrated nitric acid to a three-necked flask and stir in an ice bath. While stirring, add 5 g of graphite powder to the mixed acid and stir at 300 rpm for 15 min. Then, add 7 g of potassium permanganate dropwise. After the addition is complete, continue stirring for 1.5 h. Heat the system to 40°C and continue the reaction for 4 h. B2. After the reaction is completed, stop heating, cool the reaction solution to room temperature, add hydrogen peroxide until the reaction solution has no bubbles, transfer the reaction solution to a centrifuge tube and centrifuge at a speed of 2000 r / min for 15 minutes each time, pour out the supernatant, wash the precipitate with 5% hydrochloric acid solution 3 times, add the remaining reaction solution, and repeat this operation; after the reaction solution is centrifuged, wash the collected precipitate with deionized water until neutral, and dry the precipitate in a vacuum drying oven at 70°C for 12 hours to obtain graphene oxide solid; B3. Add 1 g of graphene oxide to 100 mL of deionized water, ultrasonically disperse for 1 hour, and then hydrothermally react at 200°C for 10 hours. After the reaction is completed, cool to room temperature to obtain a graphene quantum dot dispersion; add ammonia water dropwise to adjust the pH value of the dispersion to 10, then add 3 g of silane coupling agent KH-560 to the dispersion, and continue to stir evenly; place the reaction vessel in a constant temperature water bath at 70°C, stir at a speed of 400 r / min, and react for 4 hours; after the reaction is completed, transfer the reaction solution to a dialysis bag, dialyze with deionized water for 5 days, and replace the dialysate 3 times a day to obtain a surface-modified graphene quantum dot dispersion.

[0032] Comparative Example 1: A low-smoke, halogen-free, environmentally friendly flame retardant is prepared. The specific preparation steps are as follows: The remaining steps remained unchanged, except that the modified polycarbonate in Example 2 was replaced by polycarbonate without any treatment to prepare a low-smoke, halogen-free, and environmentally friendly flame retardant.

[0033] Comparative Example 2: A low-smoke, halogen-free, environmentally friendly flame retardant is prepared in the following steps: The remaining steps remained unchanged, except that the graphene quantum dot dispersion of Example 2 was replaced by an untreated graphene oxide dispersion to prepare a low-smoke, halogen-free, and environmentally friendly flame retardant.

[0034] Test items Test Method Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Limiting oxygen index (%) According to GB / T2406.2-2009 standard, oxygen index meter is used for testing 31 33 32 28 16 Vertical combustion level According to UL94 standard, the sample is subjected to vertical combustion test V-0 V-0 V-0 V-1 V-1 Smoke density level According to GB / T8627-2007 standard, use smoke density tester to test 15 14 15 22 25 Thermal stability Using a thermogravimetric analyzer, the temperature was raised from room temperature to 800°C at a heating rate of 10°C / min under a nitrogen atmosphere to record the thermogravimetric curve. Initial decomposition temperature 350℃, 50% weight loss temperature 480℃ Initial decomposition temperature 355℃, 50% weight loss temperature 485℃ Initial decomposition temperature 352℃, 50% weight loss temperature 482℃ Initial decomposition temperature 320℃, 50% weight loss temperature 450℃ Initial decomposition temperature 300℃, 50% weight loss temperature 420℃ Dispersion uniformity Scanning electron microscopy (SEM) was used to observe the dispersion of the flame retardant in the matrix material and evaluate the degree of dispersion uniformity. Evenly dispersed, no obvious agglomeration Evenly dispersed, no obvious agglomeration Evenly dispersed, no obvious agglomeration There is a small amount of agglomeration Agglomeration phenomenon is more obvious Tensile strength (MPa) According to GB / T1040.2-2006 standard, use universal material testing machine for testing 100 105 102 85 80 Elongation at break (%) According to GB / T1040.2-2006 standard, use universal material testing machine for testing 30 32 31 25 20 Flexural strength (MPa) According to GB / T9341-2008 standard, use universal material testing machine for testing 120 125 123 100 95 Water resistance (water absorption) (%) After the sample is immersed in distilled water for 48 hours, its mass change is measured and the water absorption rate is calculated. 0.5 0.4 0.45 0.8 1 After a comprehensive performance test of the low-smoke, halogen-free, environmentally friendly flame retardant, the results show that Examples 1-3 exhibit excellent performance advantages. In terms of flame retardant properties, the limiting oxygen index of Examples 1-3 is higher, the vertical combustion level reaches V-0, and the smoke density level is low, which is significantly better than Comparative Example 1 and Comparative Example 2, greatly reducing the risk of fire. In terms of thermal stability, the initial decomposition temperature and 50% weight loss temperature of the examples are higher, and they can remain stable at high temperatures. In terms of dispersion uniformity, the examples are well dispersed in the matrix material without obvious agglomeration, while the comparative example has agglomeration problems. In terms of mechanical properties, the tensile strength, elongation at break and flexural strength of the examples are all higher than those of the comparative example, and the material is more tough and strong. In the water resistance test, the examples have lower water absorption and better moisture resistance. Overall, compared with Comparative Example 1 and Comparative Example 2, Examples 1-3 have outstanding performance, which strongly proves that the formula and preparation process of the present invention can effectively improve the comprehensive performance of flame retardants and meet the needs of actual applications.

[0035] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from 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 low-smoke, halogen-free, environmentally friendly flame retardant, characterized by: The invention comprises the following raw materials in parts by weight: 8-12 parts of a novel phosphorus-nitrogen heterocyclic compound, 5-9 parts of a silane-terminated polyether, 2-5 parts of a graphene quantum dot dispersion, 6-10 parts of pentaerythritol diphosphate melamine salt, 5-8 parts of melamine cyanurate, 3-6 parts of zinc borate, 8-12 parts of magnesium hydroxide, 10-15 parts of ammonium polyphosphate, 3-7 parts of modified polycarbonate, 4-8 parts of aluminum diethylphosphinate, 2-4 parts of an organosilicon elastomer, 0.2-0.5 parts of triphenyl phosphite, 0.3-0.6 parts of polyethylene wax, 0.3-0.8 parts of a silane coupling agent KH-550, and 25-35 parts of deionized water.

2. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 1, characterized in that: The modified polycarbonate is specifically prepared in the following steps: A1. Slowly add dry polycarbonate to a reactor filled with toluene, heat to 60°C and stir until completely dissolved. Stop heating, wait for the solution to cool to room temperature, then add maleic anhydride and furan in sequence, and stir at an accelerated rate for 30 minutes. Raise the temperature of the reactor to 100°C and stir for 6 hours. After the reaction is complete, stop heating, cool naturally to room temperature, pour the reaction solution into methanol for precipitation while stirring, filter, wash, and dry to obtain a polycarbonate containing furan rings. A2, after grinding the product of A1, add it into a quartz glass container filled with anhydrous ethanol, heat it to 40 ° C and stir until it dissolves, pass high-purity nitrogen into the reaction container, add mercaptopropyltrimethoxysilane and benzoin dimethyl ether to the solution in sequence under light-proof conditions, and stir at an increased speed for 30 minutes; keep the nitrogen flow, irradiate the reaction solution with ultraviolet light and stir; after the reaction is completed, stop the illumination and nitrogen flow, pour the reaction solution into deionized water for precipitation, stir while pouring, filter, wash, and dry to obtain a thiol-ene modified polycarbonate; A3. Add 2,2-dihydroxymethylpropionic acid and toluene into a four-necked flask, heat to 80°C and stir to dissolve, then add p-toluenesulfonic acid and hydroquinone, stir evenly, add glycidyl acrylate dropwise, and after the addition is complete, heat to 110°C and react for 4 hours to obtain monomer 1; introduce nitrogen into another reactor, then add N,N-dimethylformamide, then add A2 product and monomer 1, heat and stir to dissolve, then add dibutyltin dilaurate, speed up the stirring reaction for 30 minutes, heat the reactor to 120°C, and stir the reaction for 6 hours; after the reaction is completed, stop heating, let the reactor cool naturally to room temperature, pour the reaction solution into methanol for precipitation, filter the precipitate, collect the solid product, wash and dry to obtain a hyperbranched polymer grafted polycarbonate.

3. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 2, characterized in that: In step A1, the ratio of polycarbonate, toluene, maleic anhydride, and furan is 10 g:50 mL:5 g:3 g; the initial stirring speed is 200 r / min, and the speed is 400 r / min after acceleration; the reactor heating rate is 5°C / min; the precipitate is washed with methanol and then dried in a vacuum drying oven at 70°C for 24 hours.

4. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 2, characterized in that: In the A2 step, the amount ratio of A1 product, anhydrous ethanol, mercaptopropyl trimethoxysilane, and benzoin dimethyl ether is 8g:40mL:4g:0.5g; the A product is ground through an 80-mesh sieve and stirred at a speed of 300r / min, and the speed is increased to 600r / min; the flow rate of nitrogen is 100mL / min, and the flow time is 15min; the wavelength is 365nm, 10mW / cm 2 The product was irradiated with strong ultraviolet light for 3 h; after filtering, it was washed with deionized water and then dried in a vacuum drying oven at 50°C for 24 h.

5. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 2, characterized in that: In the step A3, the amount ratio of 2,2-dihydroxymethylpropionic acid, glycidyl acrylate, p-toluenesulfonic acid, hydroquinone, and toluene is 10g:11g:0.5g:0.4g:50mL; the amount ratio of N,N-dimethylformamide, A2 product, monomer 1, and dibutyltin dilaurate is 40mL:6g:5g:0.3g; the initial stirring speed is 400r / min, and the speed after speed increase is 600r / min; the nitrogen flow rate is 100mL / min, and the introduction time is 15min; the reactor heating rate is 5°C / min; the product after filtration is washed with methanol, and then dried in a vacuum drying oven at 80°C for 24h.

6. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 1, characterized in that: The specific preparation steps of the graphene quantum dot dispersion are as follows: B1. Add concentrated sulfuric acid and concentrated nitric acid to a three-necked flask and stir in an ice bath. While stirring, add graphite powder to the mixed acid and stir for 15 minutes. Then, add potassium permanganate dropwise. After the addition is complete, continue stirring for 1.5 hours. Heat the system to 40°C and continue the reaction for 4 hours. B2. After the reaction is completed, heating is stopped, the reaction solution is cooled to room temperature, hydrogen peroxide is added until the reaction solution has no bubbles, the reaction solution is transferred to a centrifuge tube and centrifuged, the supernatant is poured out, and the precipitate is washed with hydrochloric acid solution. After the reaction solution is centrifuged, the collected precipitate is washed with deionized water, and finally, the washed graphene oxide is dried to obtain graphene oxide solid; B3. Add graphene oxide to deionized water, ultrasonically disperse for 1 hour, and then hydrothermally react at 200°C for 10 hours. After the reaction is completed, cool to room temperature to obtain a graphene quantum dot dispersion; add ammonia water to adjust the pH value of the dispersion to 10, then add silane coupling agent KH-560 to the dispersion and continue to stir evenly; place the reaction vessel in a constant temperature water bath at 70°C and stir the reaction for 4 hours; after the reaction is completed, transfer the reaction solution to a dialysis bag and dialyze with deionized water for 5 days, changing the dialysate 3 times a day to obtain a surface-modified graphene quantum dot dispersion.

7. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 6, characterized in that: In step B1, the ratio of concentrated sulfuric acid, concentrated nitric acid, graphite powder, and potassium permanganate is 30 mL: 10 mL: 5 g: 7 g; the stirring speed is 300 r / min; in step B2, the centrifugal speed is 2000 r / min, each centrifugation is 15 min, the supernatant is discarded, and the precipitate is washed three times with 5% hydrochloric acid solution, and the remaining reaction solution is added and this operation is repeated; after the reaction solution is centrifuged, the collected precipitate is washed with deionized water until neutral, and the precipitate is dried in a vacuum drying oven at 70°C for 12 h.

8. The low-smoke, halogen-free, environmentally friendly flame retardant according to claim 6, characterized in that: In step B3, the usage ratio of graphene oxide, deionized water, and silane coupling agent KH-560 is 1 g:100 mL:3 g; and the stirring speed is 400 r / min.

9. A method for preparing a low-smoke, halogen-free, environmentally friendly flame retardant, characterized by: The specific steps include: S1. Add zinc borate and magnesium hydroxide to a high-speed mixer and stir for 5 minutes. Then add pentaerythritol diphosphate melamine salt, melamine cyanurate, ammonium polyphosphate and aluminum diethylphosphinate, and stir at an increased speed for 5 minutes. Then add the novel phosphorus-nitrogen heterocyclic compound, silane-terminated polyether and graphene quantum dot dispersion, and stir at a maintained speed for 5 minutes. Finally, add triphenyl phosphite, polyethylene wax and silane coupling agent KH-550, and stir at an increased speed for 10 minutes. S2. Add modified polycarbonate and silicone elastomer to the pre-dispersed mixture, continue stirring for 20 minutes, then slowly add deionized water and stir for 15 minutes to form a uniform slurry; S3. Preheat the drying tower of the spray granulator, and form the slurry into granules through spray granulation; dry the granulated flame retardant particles in an oven at 80° C. for 12 hours to obtain a low-smoke halogen-free and environmentally friendly flame retardant.

10. The method for preparing a low-smoke, halogen-free, environmentally friendly flame retardant according to claim 9, characterized in that: In the step S1, the initial stirring speed is 1000 r / min, the stirring speed after accelerating is 1200 r / min, and the stirring speed after adding the additive to increase the speed is 1500 r / min; in the step S2, the stirring speed is 2000 r / min; in the step S3, the drying tower is preheated to 150°C, the feed rate is 8 L / h, the spray pressure is 0.5 MPa, the atomizer speed is 12000 r / min, and the hot air temperature is 150°C.