Flame-retardant regenerated PET composite material and preparation method thereof

Abstract

The invention discloses a flame-retardant regenerated PET composite material and a preparation method thereof.The composite material is prepared from, 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 burns, the modified filler can absorb heat, so that a metal complex on the surface is decomposed into metal oxide, flame-retardant gas and crystal water, and the flame-retardant regenerated PET composite material is obtained; the density and the strength of a dehydrated carbon layer generated by organic phosphorus are enhanced by the metal oxide and an organic silicon chain segment, the concentration of combustible gas can be reduced by generated refractory gas, and the temperature of a condensed phase can be reduced by absorption and evaporation of crystal water, so that the combustion of the composite material is inhibited, and the release of smoke and toxic gas is reduced; the internal sepiolite can be decomposed at high temperature to form a porous and compact silicate ceramic layer, so that oxygen and heat are effectively prevented from permeating inwards, combustible gas is prevented from escaping, and the flame-retardant effect is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of PET flame retardant material preparation, and 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. Both 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, making PET composite materials, as one of the five major engineering plastics, widely used in electronics, electrical appliances, communications, and automotive parts. However, with the use of a large amount 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 will produce a lot of black smoke when burned, and the flame retardant effect is not good, which increases 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 generates a large amount of black smoke when burned.

[0004] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a flame retardant recycled PET composite material comprises the following steps: Step A1: Mix waste PET material, zinc acetate and ethylene glycol uniformly, introduce nitrogen protection, react for 2-3 hours at a speed of 150-200 r / min and a temperature of 195-200° C. to obtain alcoholysis solution, mix the alcoholysis solution, methanol and sodium hydroxide uniformly, react for 2-4 hours at a speed of 120-150 r / min and a temperature of 65-70° C. to obtain dimethyl terephthalate; Step A2: octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 10-12 hours at a speed of 120-150 r / min and a temperature of 90-95° C. to obtain a dihydrogen-terminated polysiloxane; the dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid and DMF are mixed uniformly, nitrogen is introduced for protection, and the reaction is carried out for 4-6 hours at a speed of 200-300 r / min and a temperature of 80-90° C. to obtain a modified monomer; Step A3: dimethyl terephthalate, modified monomer, ethylene glycol and manganese acetate are uniformly mixed, reacted at a temperature of 160-180° C. for 2-3 hours, antimony trioxide is added, and the reaction is carried out 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 reaction is carried out at a pressure of 50-80 Pa for 20-30 minutes to obtain 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, and the raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0005] 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.

[0006] Furthermore, the molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane described 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 dihydrogen-terminated polysiloxane.

[0007] Furthermore, the dosage ratio of dimethyl terephthalate, modified monomer and ethylene glycol in step A3 is 6:1:8, the dosage of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the dosage of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0008] Further, the modified filler is prepared by the following steps: 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., reacting for 3-5 hours to obtain pretreated sepiolite, and uniformly mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone and tetrahydrofuran, 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; Step B2: uniformly mix the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide, stir and add phosphorus oxychloride at a speed of 150-200 r / min and a temperature of 60-65° C., react for 10-15 hours, cool to 20-25° C., add ammonium fluoride, and continue to react for 20-25 hours to obtain a precursor, mix the precursor, pyridine-4-carboxaldehyde and tetrahydrofuran, stir for 3-5 hours at a speed of 500-600 r / min and a temperature of 30-40° C. to obtain a modified precursor; Step B3: Disperse the modified precursor in ethanol, stir and add nickel acetate tetrahydrate at a speed of 300-500 r / min and a temperature of 70-75°C, react for 2-3 hours, filter and remove the filtrate, disperse the substrate in DMF, pass nitrogen protection, stir and add DOPO at a speed of 600-800 r / min and a temperature of 90-95°C, react for 3-5 hours, and obtain a modified filler.

[0009] Furthermore, the amount of 3-methacryloxypropyltrimethoxysilane 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 is 5‰ of the mass of 3-mercaptopropyltrimethoxysilane.

[0010] Furthermore, the amount ratio of the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 is 4g:2mL:4mL:1mL:0.6g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0011] 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.

[0012] The invention has the beneficial effects as follows: a flame-retardant recycled PET composite material disclosed by the invention comprises the following raw materials: modified PET, 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 phosphoric acid amide. The modified PET is firstly alcoholyzed with waste PET material as raw material to obtain 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, and the dimethyl terephthalate, the modified monomer and ethylene glycol are ester-exchanged and then polycondensed to obtain the modified PET.

[0013] The modified filler is prepared by treating sepiolite as a raw material with 3-methacryloxypropyltrimethoxysilane so that double bonds are grafted on the surface to obtain pretreated sepiolite. The pretreated sepiolite is reacted with 3-mercaptopropyltrimethoxysilane so that the double bonds on the pretreated sepiolite react with the mercapto groups on the 3-mercaptopropyltrimethoxysilane to obtain modified sepiolite. The modified sepiolite, 3-aminopropyltriethoxysilane and methyltriethoxysilane are hydrolyzed so that the siloxane is converted into a silanol group. Then phosphorus oxychloride is added so that the chlorine on the phosphorus oxychloride is reacted with the silanol group. The atomic site reacts with the silanol group and condenses on the surface of the modified sepiolite to obtain 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 obtain a modified precursor, the modified precursor is dispersed in ethanol, nickel acetate tetrahydrate is added to complex the pyridine and nickel ions on the modified precursor 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 obtain a modified filler.

[0014] When the PET composite material burns, the modified filler will absorb 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

[0015] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0016] Embodiment 1: A method for preparing a flame retardant recycled PET composite material, comprising the following steps: Step A1: Mix waste PET material, zinc acetate and ethylene glycol uniformly, introduce nitrogen protection, react for 2 hours at a speed of 150 r / min and a temperature of 195° C. to obtain an alcoholysis solution, mix the alcoholysis solution, methanol and sodium hydroxide uniformly, react for 2 hours at a speed of 120 r / min and a temperature of 65° C. to obtain dimethyl terephthalate; Step A2: octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 10 hours at a speed of 120 r / min and a temperature of 90° C. to obtain a dihydrogen-terminated polysiloxane; the dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, nitrogen is introduced for protection, and the reaction is carried out for 4 hours at a speed of 200 r / min and a temperature of 80° C. to obtain a modified monomer; 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, and the raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0017] 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.

[0018] The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane described 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 dihydrogen-terminated polysiloxane.

[0019] The dosage ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the dosage of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the dosage of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0020] The modified filler is prepared by the following steps: Step B1: Disperse sepiolite in ethanol, stir and add deionized water and 3-methacryloxypropyltrimethoxysilane at a speed of 200 r / min and a temperature of 60° C., and react for 3 hours to obtain pretreated sepiolite; mix the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone and tetrahydrofuran evenly, and react for 10 seconds at a speed of 120 r / min, a temperature of 20° C. and irradiation with 365 nm ultraviolet light to obtain modified sepiolite; Step B2: uniformly mix the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide, stir and add phosphorus oxychloride at a speed of 150 r / min and a temperature of 60° C., react for 10 h, cool to 20° C., add ammonium fluoride, and continue to react for 20 h to obtain a precursor, mix the precursor, pyridine-4-carboxaldehyde and tetrahydrofuran, stir for 3 h at a speed of 500 r / min and a temperature of 30° C. to obtain a modified precursor; Step B3: The modified precursor is dispersed in ethanol, stirred and nickel acetate tetrahydrate is added at a speed of 300 r / min and a temperature of 70°C, and the reaction is carried out for 2 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 r / min and a temperature of 90°C. The reaction is carried out for 3 hours to obtain a modified filler.

[0021] 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.

[0022] The amount ratio of the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 is 4g:2mL:4mL:1mL:0.6g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0023] 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.

[0024] Embodiment 2: A method for preparing a flame retardant recycled PET composite material, comprising the following steps: Step A1: Mix waste PET material, zinc acetate and ethylene glycol uniformly, introduce nitrogen protection, react for 2 hours at a speed of 150 r / min and a temperature of 200° C. to obtain an alcoholysis solution, mix the alcoholysis solution, methanol and sodium hydroxide uniformly, react for 3 hours at a speed of 120 r / min and a temperature of 70° C. to obtain dimethyl terephthalate; Step A2: octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 10-12 hours at a speed of 120 r / min and a temperature of 95° C. to obtain a dihydrogen-terminated polysiloxane; the dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, nitrogen is introduced for protection, and the reaction is carried out for 5 hours at a speed of 200 r / min and a temperature of 85° C. to obtain a modified monomer; 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, and the raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0025] 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.

[0026] The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane described 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 dihydrogen-terminated polysiloxane.

[0027] The dosage ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the dosage of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the dosage of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0028] The modified filler is prepared by the following steps: Step B1: Disperse sepiolite in ethanol, stir and add deionized water and 3-methacryloxypropyltrimethoxysilane at a speed of 200 r / min and a temperature of 65° C., and react for 4 hours to obtain pretreated sepiolite; mix the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone and tetrahydrofuran evenly, and react 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; Step B2: uniformly mix the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide, stir and add phosphorus oxychloride at a speed of 200 r / min and a temperature of 60°C, react for 15 hours, cool to 20°C, add ammonium fluoride, and continue to react for 25 hours to obtain a precursor, mix the precursor, pyridine-4-carboxaldehyde and tetrahydrofuran, stir for 4 hours at a speed of 500 r / min and a temperature of 35°C to obtain a modified precursor; Step B3: Disperse the modified precursor in ethanol, stir and add nickel acetate tetrahydrate at a speed of 300 r / min and a temperature of 75°C, react for 2 hours, filter and remove the filtrate, disperse the substrate in DMF, pass nitrogen protection, stir and add DOPO at a speed of 800 r / min and a temperature of 90°C, react for 4 hours to obtain a modified filler.

[0029] 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.

[0030] The amount ratio of the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 is 4g:2mL:4mL:1mL:0.6g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0031] 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.

[0032] Embodiment 3: A method for preparing a flame retardant recycled PET composite material, comprising the following steps: Step A1: Mix waste PET material, zinc acetate and ethylene glycol uniformly, introduce nitrogen protection, react for 3 hours at a speed of 200 r / min and a temperature of 200° C. to obtain an alcoholysis solution, mix the alcoholysis solution, methanol and sodium hydroxide uniformly, react for 4 hours at a speed of 150 r / min and a temperature of 70° C. to obtain dimethyl terephthalate; Step A2: octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the reaction is carried out for 12 hours at a speed of 150 r / min and a temperature of 95° C. to obtain a dihydrogen-terminated polysiloxane; the dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid and DMF are mixed evenly, nitrogen is introduced for protection, and the reaction is carried out for 6 hours at a speed of 300 r / min and a temperature of 90° C. to obtain a modified monomer; Step A3: dimethyl terephthalate, modified monomer, ethylene glycol and manganese acetate are uniformly mixed, reacted at a temperature of 180° C. for 3 hours, antimony trioxide is added, and the reaction is carried out at a temperature of 240° C. and a pressure of 0.5 MPa for 5 hours. The temperature is raised to 285° C. and the reaction is carried out at a pressure of 80 Pa for 30 minutes to obtain modified PET. The following raw materials are weighed in parts by weight: 120 parts of modified PET, 25 parts of modified filler, 15 parts of pyrophosphate and 5 parts of calcium hydroxide, and the raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

[0033] 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.

[0034] The molar ratio of octamethylcyclotetrasiloxane, tetramethylammonium hydroxide and tetramethyldisiloxane described 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 dihydrogen-terminated polysiloxane.

[0035] The dosage ratio of dimethyl terephthalate, modified monomer and ethylene glycol described in step A3 is 6:1:8, the dosage of manganese acetate is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol, and the dosage of antimony trioxide is 2% of the total mass of dimethyl terephthalate, modified monomer and ethylene glycol.

[0036] The modified filler is prepared by the following steps: Step B1: Disperse sepiolite in ethanol, stir and add deionized water and 3-methacryloxypropyltrimethoxysilane at a speed of 300 r / min and a temperature of 70°C, and react for 5 hours to obtain pretreated sepiolite; mix the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone and tetrahydrofuran evenly, and react for 15 seconds at a speed of 150 r / min, a temperature of 25°C and irradiation with 365 nm ultraviolet light to obtain modified sepiolite; Step B2: uniformly mix the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide, stir and add phosphorus oxychloride at a speed of 200 r / min and a temperature of 65° C., react for 15 h, cool to 25° C., add ammonium fluoride, and continue to react for 25 h to obtain a precursor, mix the precursor, pyridine-4-carboxaldehyde and tetrahydrofuran, stir for 5 h at a speed of 600 r / min and a temperature of 40° C. to obtain a modified precursor; 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, and the reaction was carried out for 3 hours. The filtrate was filtered to remove the filtrate, and the substrate was dispersed in DMF. Nitrogen was introduced for protection, and DOPO was added at a speed of 800 r / min and a temperature of 95°C. The reaction was carried out for 5 hours to obtain a modified filler.

[0037] 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.

[0038] The amount ratio of the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 is 4g:2mL:4mL:1mL:0.6g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:1.

[0039] 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.

[0040] Comparative Example 1: Compared with Example 1, no modified monomer was added to this comparative example, and the remaining steps were the same.

[0041] Comparative Example 2: Compared with Example 1, pyrophosphoric acid was not added in this comparative example, and the remaining steps were the same.

[0042] Comparative Example 3: Compared with Example 1, this comparative example uses graphene oxide instead of sepiolite, and the other steps are the same.

[0043] 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.

[0044] The composite materials obtained in Examples 1-3 and Comparative Examples 1-4 were made into 125 mm × 13 mm × 10 mm 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 75 mm × 75 mm × 1 mm samples according to the standard of ISO5659-2, and the vertical combustion level was tested. 2 Under the conditions, the maximum smoke release rate and smoke release amount were tested, and the test results are shown in Table 1 below.

[0045] Table 1 Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 3 Comparative Example 3 Comparative Example 4 Vertical burning 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 It can be seen from the above table that the present invention has a good flame retardant and smoke suppression effect.

[0046] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described 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 protection scope 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: mixing waste PET material, zinc acetate and ethylene glycol uniformly, introducing nitrogen protection, reacting to obtain alcoholysis solution, and mixing the alcoholysis solution, methanol and sodium hydroxide uniformly, reacting to obtain dimethyl terephthalate; Step A2: octamethylcyclotetrasiloxane, tetramethylammonium hydroxide, tetramethyldisiloxane and dimethyl sulfoxide are mixed, nitrogen is introduced for protection, and the mixture is reacted to obtain dihydrogen-terminated polysiloxane; dihydrogen-terminated polysiloxane, allyl alcohol, chloroplatinic acid and DMF are uniformly mixed, nitrogen is introduced for protection, and the mixture is reacted to obtain a modified monomer; Step A3: After dimethyl terephthalate, modified monomer, ethylene glycol and manganese acetate are mixed and reacted, antimony trioxide is added and reacted to obtain 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, and the raw materials are melt-extruded to obtain a flame-retardant recycled PET composite material.

2. The method for preparing a flame retardant recycled PET composite material according to claim 1, characterized in that: 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, characterized in that: 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, characterized in that: 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, characterized in that: 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, and mixing the pretreated sepiolite, 3-mercaptopropyltrimethoxysilane, benzophenone and tetrahydrofuran to react to obtain modified sepiolite; Step B2: uniformly mixing the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane and dimethyl sulfoxide, stirring and adding phosphorus oxychloride to react, cooling and adding ammonium fluoride to continue the reaction to obtain a precursor, and mixing and stirring the precursor, pyridine-4-carboxaldehyde and tetrahydrofuran to obtain a modified precursor; Step B3: Disperse the modified precursor in ethanol, stir and add nickel acetate tetrahydrate, react, filter and remove the filtrate, disperse the substrate in DMF, pass nitrogen protection, stir and add DOPO, react, and obtain a modified filler.

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

1.

7. The method for preparing a flame retardant recycled PET composite material according to claim 5, characterized in that: The amount ratio of the modified sepiolite, 3-aminopropyltriethoxysilane, methyltriethoxysilane, phosphorus oxychloride and ammonium fluoride described in step B2 is 4g:2mL:4mL:1mL:0.6g, and the molar ratio of the amino group on the precursor to pyridine-4-carboxaldehyde is 2:

1.

8. The method for preparing a flame retardant recycled PET composite material according to claim 5, characterized in that: 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.

9. A flame retardant recycled PET composite material, characterized in that: Prepared according to any one of the preparation methods described in claims 1-8.