A flame-retardant recycled PET composite material and preparation method thereof

Abstract

The invention discloses a flame-retardant recycled PET composite material and a preparation method thereof. The composite material comprises the following raw materials in parts by weight: 100-120 parts of modified PET, 20-25 parts of modified filler, 10-15 parts of pyrophosphoric acid, and 2-5 parts of calcium hydroxide. When the PET composite material is burned, the modified filler absorbs heat, causing metal complexes on the surface to decompose into metal oxides, flame-retardant gases, and crystal water. The metal oxides react with organic silicon segments to enhance the density and strength of a dehydrated carbon layer generated by organic phosphorus. The generated flame-retardant gases can reduce the concentration of combustible gases. The absorption and evaporation of crystal water can reduce the temperature of a condensed phase, thereby inhibiting the combustion of the composite material and reducing the release of smoke and toxic gases. In addition, the sepiolite inside the composite material can decompose at high temperatures to form a porous, dense silicate ceramic layer, effectively isolating oxygen and heat from penetrating inward, while preventing the escape of combustible gases, thereby further improving the flame retardant effect.

Description

Technical Field

[0001] The present invention relates to the technical field of PET flame retardant material preparation, in particular to a flame retardant recycled PET composite material and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET) is a semi-crystalline polyester with a benzene ring, an ester group and a flexible alkane chain structure in its molecular chain. The two ends of the benzene ring are connected to the ester group to form a conjugated structure with extremely rigid chains. The products have excellent wear resistance, heat resistance, and chemical resistance. This makes PET composite materials, as one of the five major engineering plastics, widely used in electronics, electrical appliances, communications, and automotive parts. However, with the large-scale use of PET materials, a lot of waste has appeared. In order to solve this problem, a process of secondary processing of waste PET materials to prepare recycled PET has emerged. However, due to insufficient impurity removal, recycled PET produces a large amount of black smoke when burned, and the flame retardant effect is poor, increasing safety hazards. Summary of the Invention

[0003] The purpose of the present invention is to provide a flame-retardant recycled PET composite material and a preparation method thereof, which solves the problem that the current recycled PET material has poor flame retardant effect and produces a large amount of black smoke when burned.

[0004] The purpose of the present invention can be achieved through the following technical solutions:

[0005] A method for preparing a flame-retardant recycled PET composite material comprises the following steps:

[0006] Step A1: waste PET material, zinc acetate, and ethylene glycol are uniformly mixed, nitrogen protection is introduced, and the reaction is carried out at a speed of 150-200 r / min and a temperature of 195-200° C. for 2-3 hours to obtain an alcoholysis solution. The alcoholysis solution, methanol, and sodium hydroxide are uniformly mixed, and the reaction is carried out at a speed of 120-150 r / min and a temperature of 65-70° C. for 2-4 hours to obtain dimethyl terephthalate;

[0007] Step A2: Octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane, and dimethyl sulfoxide are mixed, nitrogen is introduced, and the reaction is carried out at a speed of 120-150 r / min and a temperature of 90-95° C. for 10-12 hours to obtain a dihydrogen-terminated polysiloxane. The dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid, and DMF are uniformly mixed, nitrogen is introduced, and the reaction is carried out at a speed of 200-300 r / min and a temperature of 80-90° C. for 4-6 hours to obtain a modified monomer.

[0008] Step A3: Dimethyl terephthalate, a modified monomer, ethylene glycol, and manganese acetate are uniformly mixed and reacted at a temperature of 160-180° C. for 2-3 hours. Antimony trioxide is then added and reacted at a temperature of 230-240° C. and a pressure of 0.3-0.5 MPa for 3-5 hours. The temperature is raised to 280-285° C. and the pressure is 50-80 Pa, and the reaction is carried out for 20-30 minutes to obtain a modified PET. The following raw materials are weighed in parts by weight: 100-120 parts of modified PET, 20-25 parts of modified filler, 10-15 parts of pyrophosphoric acid, and 2-5 parts of calcium hydroxide. The raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0009] Furthermore, the mass ratio of the waste PET material and ethylene glycol described in step A1 is 2:1, the amount of zinc acetate used is 2‰ of the mass of the waste PET material, and the mass ratio of the alcoholysis solution, methanol and sodium hydroxide is 500:1500:1.

[0010] Furthermore, the molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane in step A2 is 2:2:3, the molar ratio of dihydrogen-terminated polysiloxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of the dihydrogen-terminated polysiloxane.

[0011] Furthermore, the amount ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the amount of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the amount of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0012] Furthermore, the modified filler is prepared by the following steps:

[0013] Step B1: Dispersing sepiolite in ethanol, stirring and adding deionized water and 3-methacryloxypropyltrimethoxysilane at a speed of 200-300 r / min and a temperature of 60-70°C, and reacting for 3-5 hours to obtain pretreated sepiolite; uniformly mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone, and tetrahydrofuran, and reacting for 10-15 seconds at a speed of 120-150 r / min, a temperature of 20-25°C, and irradiating with 365 nm ultraviolet light to obtain modified sepiolite;

[0014] Step B2: The modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide are uniformly mixed, and phosphorus oxychloride is added at a speed of 150-200 r / min and a temperature of 60-65° C., and the reaction is carried out for 10-15 hours. The temperature is lowered to 20-25° C., ammonium fluoride is added, and the reaction is continued for 20-25 hours to obtain a precursor. The precursor, pyridine-4-carboxaldehyde and tetrahydrofuran are mixed, and the mixture is stirred at a speed of 500-600 r / min and a temperature of 30-40° C. for 3-5 hours to obtain a modified precursor;

[0015] Step B3: The modified precursor is dispersed in ethanol, stirred at a speed of 300-500 r / min and a temperature of 70-75°C, and nickel acetate tetrahydrate is added. After reacting for 2-3 hours, the filtrate is filtered to remove the filtrate, and the substrate is dispersed in DMF. Nitrogen is introduced for protection, and DOPO is added at a speed of 600-800 r / min and a temperature of 90-95°C. The reaction is carried out for 3-5 hours to obtain a modified filler.

[0016] Furthermore, the amount of 3-methacryloxypropyltrimethoxysilane described in step B1 is 5% of the mass of sepiolite, the molar ratio of the double bonds on the pretreated sepiolite and 3-mercaptopropyltrimethoxysilane is 1:1, and the amount of benzophenone is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane.

[0017] Furthermore, the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 are used in a ratio of 4 g:2 mL:4 mL:1 mL:0.6 g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0018] Furthermore, the amount ratio of the modified precursor, ethanol and nickel acetate tetrahydrate described in step B3 is 1 g:100 mL:0.2 g, and the mass ratio of the substrate and DOPO is 1:2.

[0019] The invention has the beneficial effects as follows: a flame-retardant recycled PET composite material disclosed in the invention comprises the following raw materials: modified PET, a modified filler, pyrophosphoric acid and calcium hydroxide; when the raw materials are blended, the pyrophosphoric acid and the amino groups on the surface of the modified filler react under the action of calcium hydroxide to form phosphoamide; the modified PET is first alcoholyzed with waste PET material as raw material to obtain an alcoholysis solution; the alcoholysis solution is treated with sodium hydroxide to obtain dimethyl terephthalate; octamethylcyclotetrasiloxane is ring-opened and polycondensed, and then end-capped with tetramethyldisiloxane to obtain dihydrogen-terminated polysiloxane; the dihydrogen-terminated polysiloxane is reacted with allyl alcohol, so that the Si-H bond on the dihydrogen-terminated polysiloxane reacts with the double bond on the allyl alcohol to form a diol end-capping to obtain a modified monomer; the dimethyl terephthalate, the modified monomer and ethylene glycol are ester-exchanged and then polycondensed to obtain the modified PET.

[0020] The modified filler is prepared by treating sepiolite with 3-methacryloyloxypropyltrimethoxysilane to graft double bonds on the surface to obtain pretreated sepiolite. The pretreated sepiolite is reacted with 3-mercaptopropyltrimethoxysilane to react the double bonds on the pretreated sepiolite with the mercapto groups on the 3-mercaptopropyltrimethoxysilane to obtain modified sepiolite. The modified sepiolite, 3-aminopropyltriethoxysilane and methyltriethoxysilane are hydrolyzed to convert siloxane into silanol groups. Then, phosphorus oxychloride is added to react the chlorine groups on the phosphorus oxychloride. The atomic sites react with silanol groups and condense on the surface of modified sepiolite to prepare a precursor, the precursor is reacted with pyridine-4-carboxaldehyde, so that the amino group on the precursor reacts with the aldehyde group on the pyridine-4-carboxaldehyde to form a carbon-nitrogen double bond to prepare a modified precursor, the modified precursor is dispersed in ethanol, nickel acetate tetrahydrate is added, so that the pyridine on the modified precursor is complexed with nickel ions to form a metal complex on the surface, and DOPO is added to graft the PH bond on the DOPO and the carbon-nitrogen double bond on the substrate to prepare a modified filler.

[0021] When the PET composite material burns, the modified filler absorbs heat, causing the metal complex on the surface to decompose into metal oxides, flame-retardant gases and crystal water. The metal oxides will combine with the silicone segments to enhance the density and strength of the dehydrated carbon layer produced by the organophosphorus. The flame-retardant gases produced can reduce the concentration of combustible gases. The absorption and evaporation of crystal water can lower the temperature of the condensed phase, thereby inhibiting the combustion of the composite material and reducing the release of smoke and toxic gases. The internal sepiolite can decompose at high temperatures to form a porous, dense silicate ceramic layer, which effectively isolates oxygen and heat from penetrating inward, while preventing the escape of combustible gases, further enhancing the flame retardant effect. DETAILED DESCRIPTION

[0022] 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.

[0023] Example 1: A method for preparing a flame-retardant recycled PET composite material, comprising the following steps:

[0024] Step A1: waste PET material, zinc acetate, and ethylene glycol are uniformly mixed, nitrogen protection is introduced, and the mixture is reacted at a speed of 150 r / min and a temperature of 195° C. for 2 hours to obtain an alcoholysis solution. The alcoholysis solution, methanol, and sodium hydroxide are uniformly mixed, and the mixture is reacted at a speed of 120 r / min and a temperature of 65° C. for 2 hours to obtain dimethyl terephthalate;

[0025] Step A2: Octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane, and dimethyl sulfoxide were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 120 r / min and a temperature of 90° C. for 10 hours to obtain a dihydrogen-terminated polysiloxane. The dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid, and DMF were uniformly mixed, nitrogen was introduced, and the mixture was reacted at a speed of 200 r / min and a temperature of 80° C. for 4 hours to obtain a modified monomer.

[0026] Step A3: Dimethyl terephthalate, modified monomer, ethylene glycol and manganese acetate are uniformly mixed, reacted at a temperature of 160° C. for 2 hours, antimony trioxide is added, and the reaction is carried out at a temperature of 230° C. and a pressure of 0.3 MPa for 3 hours. The temperature is raised to 280° C. and the reaction is carried out at a pressure of 50 Pa for 20 minutes to obtain modified PET. The following raw materials are weighed in parts by weight: 100 parts of modified PET, 20 parts of modified filler, 10 parts of pyrophosphoric acid and 2 parts of calcium hydroxide. The raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0027] The mass ratio of the waste PET material and ethylene glycol described in step A1 is 2:1, the amount of zinc acetate used is 2‰ of the mass of the waste PET material, and the mass ratio of the alcoholysis solution, methanol and sodium hydroxide is 500:1500:1.

[0028] The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane in step A2 is 2:2:3, the molar ratio of dihydrogen-terminated polysiloxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of the dihydrogen-terminated polysiloxane.

[0029] The amount ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the amount of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the amount of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0030] The modified filler is prepared by the following steps:

[0031] Step B1: Dispersing sepiolite in ethanol, stirring at a speed of 200 r / min and a temperature of 60°C, adding deionized water and 3-methacryloxypropyltrimethoxysilane, and reacting for 3 hours to obtain pretreated sepiolite, and uniformly mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone, and tetrahydrofuran, and reacting for 10 seconds at a speed of 120 r / min, a temperature of 20°C, and irradiating with 365 nm ultraviolet light to obtain modified sepiolite;

[0032] Step B2: The modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide were mixed uniformly, stirred at a speed of 150 r / min and a temperature of 60°C, and phosphorus oxychloride was added to react for 10 hours. The temperature was lowered to 20°C, ammonium fluoride was added, and the reaction was continued for 20 hours to obtain a precursor. The precursor, pyridine-4-carboxaldehyde and tetrahydrofuran were mixed and stirred at a speed of 500 r / min and a temperature of 30°C for 3 hours to obtain a modified precursor;

[0033] Step B3: The modified precursor was dispersed in ethanol, stirred at a speed of 300 r / min and a temperature of 70°C and nickel acetate tetrahydrate was added. After reacting for 2 hours, the filtrate was filtered to remove the filtrate, and the substrate was dispersed in DMF. Nitrogen was introduced for protection. DOPO was added under stirring at a speed of 600 r / min and a temperature of 90°C, and the reaction was carried out for 3 hours to obtain a modified filler.

[0034] The amount of 3-methacryloxypropyltrimethoxysilane used in step B1 is 5% of the mass of sepiolite, the molar ratio of the double bonds on the pretreated sepiolite to 3-mercaptopropyltrimethoxysilane is 1:1, and the amount of benzophenone used is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane.

[0035] The modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 are used in a ratio of 4 g:2 mL:4 mL:1 mL:0.6 g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0036] The amount ratio of the modified precursor, ethanol and nickel acetate tetrahydrate described in step B3 is 1 g:100 mL:0.2 g, and the mass ratio of the substrate to DOPO is 1:2.

[0037] Example 2: A method for preparing a flame-retardant recycled PET composite material, comprising the following steps:

[0038] Step A1: waste PET material, zinc acetate, and ethylene glycol are uniformly mixed, nitrogen protection is introduced, and the mixture is reacted at a speed of 150 r / min and a temperature of 200° C. for 2 hours to obtain an alcoholysis solution. The alcoholysis solution, methanol, and sodium hydroxide are uniformly mixed, and the mixture is reacted at a speed of 120 r / min and a temperature of 70° C. for 3 hours to obtain dimethyl terephthalate;

[0039] Step A2: Octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane, and dimethyl sulfoxide were mixed, nitrogen was introduced, and the reaction was carried out at a speed of 120 r / min and a temperature of 95° C. for 10-12 hours to obtain a dihydrogen-terminated polysiloxane. The dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid, and DMF were mixed uniformly, nitrogen was introduced, and the reaction was carried out at a speed of 200 r / min and a temperature of 85° C. for 5 hours to obtain a modified monomer.

[0040] Step A3: Dimethyl terephthalate, modified monomer, ethylene glycol and manganese acetate are uniformly mixed, reacted at a temperature of 170° C. for 3 hours, antimony trioxide is added, and the reaction is carried out at a temperature of 235° C. and a pressure of 0.4 MPa for 4 hours. The temperature is raised to 280° C. and the reaction is carried out at a pressure of 65 Pa for 25 minutes to obtain modified PET. The following raw materials are weighed in parts by weight: 110 parts of modified PET, 25 parts of modified filler, 10 parts of pyrophosphoric acid and 3 parts of calcium hydroxide. The raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0041] The mass ratio of the waste PET material and ethylene glycol described in step A1 is 2:1, the amount of zinc acetate used is 2‰ of the mass of the waste PET material, and the mass ratio of the alcoholysis solution, methanol and sodium hydroxide is 500:1500:1.

[0042] The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane in step A2 is 2:2:3, the molar ratio of dihydrogen-terminated polysiloxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of the dihydrogen-terminated polysiloxane.

[0043] The amount ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the amount of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the amount of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0044] The modified filler is prepared by the following steps:

[0045] Step B1: Dispersing sepiolite in ethanol, stirring at a speed of 200 r / min and a temperature of 65° C., adding deionized water and 3-methacryloxypropyltrimethoxysilane, and reacting for 4 hours to obtain pretreated sepiolite, and uniformly mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone, and tetrahydrofuran, and reacting for 10 seconds at a speed of 120 r / min, a temperature of 25° C., and irradiation with 365 nm ultraviolet light to obtain modified sepiolite;

[0046] Step B2: Modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, and dimethyl sulfoxide were uniformly mixed, stirred at a speed of 200 r / min and a temperature of 60°C, and phosphorus oxychloride was added to react for 15 hours. The temperature was lowered to 20°C, ammonium fluoride was added, and the reaction was continued for 25 hours to obtain a precursor. The precursor, pyridine-4-carboxaldehyde, and tetrahydrofuran were mixed and stirred at a speed of 500 r / min and a temperature of 35°C for 4 hours to obtain a modified precursor;

[0047] Step B3: The modified precursor was dispersed in ethanol, stirred at a speed of 300 r / min and a temperature of 75°C, and nickel acetate tetrahydrate was added. After reacting for 2 hours, the filtrate was filtered to remove the filtrate, and the substrate was dispersed in DMF. Nitrogen was introduced for protection. DOPO was added with stirring at a speed of 800 r / min and a temperature of 90°C, and the reaction was carried out for 4 hours to obtain a modified filler.

[0048] The amount of 3-methacryloxypropyltrimethoxysilane used in step B1 is 5% of the mass of sepiolite, the molar ratio of the double bonds on the pretreated sepiolite to 3-mercaptopropyltrimethoxysilane is 1:1, and the amount of benzophenone used is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane.

[0049] The modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 are used in a ratio of 4 g:2 mL:4 mL:1 mL:0.6 g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0050] The amount ratio of the modified precursor, ethanol and nickel acetate tetrahydrate described in step B3 is 1 g:100 mL:0.2 g, and the mass ratio of the substrate to DOPO is 1:2.

[0051] Example 3: A method for preparing a flame-retardant recycled PET composite material, comprising the following steps:

[0052] Step A1: waste PET material, zinc acetate, and ethylene glycol were uniformly mixed, nitrogen protection was introduced, and the reaction was carried out at a speed of 200 r / min and a temperature of 200° C. for 3 hours to obtain an alcoholysis solution. The alcoholysis solution, methanol, and sodium hydroxide were uniformly mixed, and the reaction was carried out at a speed of 150 r / min and a temperature of 70° C. for 4 hours to obtain dimethyl terephthalate;

[0053] Step A2: Octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane, and dimethyl sulfoxide were mixed, nitrogen was introduced, and the mixture was reacted at a speed of 150 r / min and a temperature of 95° C. for 12 hours to obtain a dihydrogen-terminated polysiloxane. The dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid, and DMF were mixed uniformly, nitrogen was introduced, and the mixture was reacted at a speed of 300 r / min and a temperature of 90° C. for 6 hours to obtain a modified monomer.

[0054] Step A3: Dimethyl terephthalate, a modified monomer, ethylene glycol, and manganese acetate were uniformly mixed, reacted at a temperature of 180° C. for 3 hours, and then antimony trioxide was added. The reaction was carried out at a temperature of 240° C. and a pressure of 0.5 MPa for 5 hours. The temperature was raised to 285° C. and the reaction was carried out at a pressure of 80 Pa for 30 minutes to obtain modified PET. The following raw materials were weighed in parts by weight: 120 parts of modified PET, 25 parts of modified filler, 15 parts of pyrophosphoric acid, and 5 parts of calcium hydroxide. The raw materials were melt-extruded to obtain a flame-retardant recycled PET composite material.

[0055] The mass ratio of the waste PET material and ethylene glycol described in step A1 is 2:1, the amount of zinc acetate used is 2‰ of the mass of the waste PET material, and the mass ratio of the alcoholysis solution, methanol and sodium hydroxide is 500:1500:1.

[0056] The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane in step A2 is 2:2:3, the molar ratio of dihydrogen-terminated polysiloxane and allyl alcohol is 1:2, and the amount of chloroplatinic acid used is 1‰ of the mass of the dihydrogen-terminated polysiloxane.

[0057] The amount ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the amount of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the amount of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0058] The modified filler is prepared by the following steps:

[0059] Step B1: Dispersing sepiolite in ethanol, stirring at a speed of 300 r / min and a temperature of 70°C, adding deionized water and 3-methacryloxypropyltrimethoxysilane, and reacting for 5 hours to obtain pretreated sepiolite; mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone, and tetrahydrofuran, and reacting for 15 seconds at a speed of 150 r / min, a temperature of 25°C, and irradiating with 365 nm ultraviolet light to obtain modified sepiolite;

[0060] Step B2: Modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, and dimethyl sulfoxide were uniformly mixed, stirred at a speed of 200 r / min and a temperature of 65° C., and phosphorus oxychloride was added to react for 15 hours. The temperature was lowered to 25° C., ammonium fluoride was added, and the reaction was continued for 25 hours to obtain a precursor. The precursor, pyridine-4-carboxaldehyde, and tetrahydrofuran were mixed, and stirred at a speed of 600 r / min and a temperature of 40° C. for 5 hours to obtain a modified precursor;

[0061] Step B3: The modified precursor was dispersed in ethanol, stirred at a speed of 500 r / min and a temperature of 75°C and nickel acetate tetrahydrate was added. After reacting for 3 hours, the filtrate was filtered to remove the filtrate, and the substrate was dispersed in DMF. Nitrogen was introduced for protection. DOPO was added under stirring at a speed of 800 r / min and a temperature of 95°C, and the reaction was carried out for 5 hours to obtain a modified filler.

[0062] The amount of 3-methacryloxypropyltrimethoxysilane used in step B1 is 5% of the mass of sepiolite, the molar ratio of the double bonds on the pretreated sepiolite to 3-mercaptopropyltrimethoxysilane is 1:1, and the amount of benzophenone used is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane.

[0063] The modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 are used in a ratio of 4 g:2 mL:4 mL:1 mL:0.6 g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0064] The amount ratio of the modified precursor, ethanol and nickel acetate tetrahydrate described in step B3 is 1 g:100 mL:0.2 g, and the mass ratio of the substrate to DOPO is 1:2.

[0065] Comparative Example 1: Compared with Example 1, no modifying monomer was added to this comparative example, and the remaining steps were the same.

[0066] Comparative Example 2: Compared with Example 1, this comparative example did not add pyrophosphoric acid, and the remaining steps were the same.

[0067] Comparative Example 3: Compared with Example 1, this comparative example uses graphene oxide instead of sepiolite, and the other steps are the same.

[0068] Comparative Example 4: Compared with Example 1, this comparative example uses a modified precursor instead of a modified filler, and the remaining steps are the same.

[0069] The composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were made into 125mm×13mm×10mm samples according to the standard of GB / T2408-2008, and the vertical combustion level was tested. The composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were made into 75mm×75mm×1mm samples according to the standard of ISO5659-2, and the vertical combustion level was tested. 2 Under the conditions of , the maximum smoke release rate and smoke release amount were tested, and the test results are shown in Table 1 below.

[0070] Table 1

[0071] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 3 Comparative Example 3 Comparative Example 4 Vertical combustion level V0 V0 V0 V1 V1 V0 V1 <![CDATA[Maximum smoke release rate m 2 / s]]> 0.027 0.019 0.015 0.082 0.047 0.054 0.093 <![CDATA[Smoke release amount m 2 > 12.7 11.1 10.3 23.4 21.7 18.4 24.2

[0072] It can be seen from the above table that this application has a very good flame retardant and smoke suppression effect.

[0073] 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 flame-retardant recycled PET composite material, characterized in that: The specific steps include: Step A1: uniformly mixing waste PET material, zinc acetate, and ethylene glycol, introducing nitrogen protection, and reacting to obtain an alcoholysis solution; uniformly mixing the alcoholysis solution, methanol, and sodium hydroxide, and reacting to obtain dimethyl terephthalate; Step A2: Octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane, and dimethyl sulfoxide are mixed, nitrogen is introduced, and the mixture is reacted to obtain a dihydrogen-terminated polysiloxane; the dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid, and DMF are uniformly mixed, nitrogen is introduced, and the mixture is reacted to obtain a modified monomer; Step A3: After dimethyl terephthalate, a modified monomer, ethylene glycol, and manganese acetate are mixed and reacted, antimony trioxide is added and reacted to produce modified PET. The following raw materials are weighed in parts by weight: 100-120 parts of modified PET, 20-25 parts of modified filler, 10-15 parts of pyrophosphoric acid, and 2-5 parts of calcium hydroxide. The raw materials are melt-extruded to produce a flame-retardant recycled PET composite material. The modified filler is prepared by the following steps: Step B1: dispersing sepiolite in ethanol, stirring, and adding deionized water and 3-methacryloxypropyltrimethoxysilane to react to obtain pretreated sepiolite; mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone, and tetrahydrofuran to react to obtain modified sepiolite; Step B2: uniformly mixing modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, and dimethyl sulfoxide, stirring, adding phosphorus oxychloride, reacting, cooling, adding ammonium fluoride, and continuing the reaction to obtain a precursor, and mixing the precursor, pyridine-4-carboxaldehyde, and tetrahydrofuran, stirring to obtain a modified precursor; Step B3: The modified precursor is dispersed in ethanol, stirred and nickel acetate tetrahydrate is added, and after reaction, the filtrate is filtered to remove the filtrate, and the substrate is dispersed in DMF, nitrogen is introduced, stirred and DOPO is added, and reaction is carried out to obtain a modified filler.

2. The method for preparing a flame-retardant recycled PET composite material according to claim 1, wherein: The mass ratio of the waste PET material and ethylene glycol described in step A1 is 2:1, and the mass ratio of the alcoholysis solution, methanol and sodium hydroxide is 500:1500:

1.

3. The method for preparing a flame-retardant recycled PET composite material according to claim 1, wherein: The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane described in step A2 is 2:2:3, and the molar ratio of dihydrogen-terminated polysiloxane and allyl alcohol is 1:

2.

4. The method for preparing a flame-retardant recycled PET composite material according to claim 1, wherein: The usage ratio of dimethyl terephthalate, modified monomer and ethylene glycol in step A3 is 6:1:

8.

5. The method for preparing a flame-retardant recycled PET composite material according to claim 1, wherein: The amount of 3-methacryloxypropyltrimethoxysilane used in step B1 is 5% of the mass of the sepiolite, and the molar ratio of the double bonds on the pretreated sepiolite to 3-mercaptopropyltrimethoxysilane is 1:

1.

6. The method for preparing a flame-retardant recycled PET composite material according to claim 1, wherein: The modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 are used in a ratio of 4 g:2 mL:4 mL:1 mL:0.6 g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:

1.

7. The method for preparing a flame-retardant recycled PET composite material according to claim 1, wherein: The amount ratio of the modified precursor, ethanol and nickel acetate tetrahydrate described in step B3 is 1 g:100 mL:0.2 g, and the mass ratio of the substrate to DOPO is 1:

2.

8. A flame-retardant recycled PET composite material, characterized by: Prepared according to any one of claims 1 to 7.