Flame-retardant PET / PUR composite material and preparation method thereof

Abstract

The invention discloses a flame-retardant PET / PUR composite material and a preparation method thereof in the technical field of composite materials. The flame-retardant PET / PUR composite material comprises the following components in parts by weight: 16-20 parts of polyethylene glycol terephthalate, 130-150 parts of modified polyurethane and 1.3-1.6 parts of a high-nitrogen synergistic flame retardant. The nitrogen-silicon flame retardant is prepared in the mode that silicon dioxide and an organic metal frame are sequentially loaded on the carbon nanotubes, integration of nitrogen-silicon flame retardant components is achieved, the dispersity of the nitrogen-silicon flame retardant components in the composite material is improved, polyurethane is modified with melamine polyphosphate, and then the technical effect of nitrogen-phosphorus-silicon synergistic flame retardance is achieved.

Description

Technical Field

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

[0002] PET, or polyethylene terephthalate, is widely used in disposable beverage bottles and food packaging due to its non-toxic, durable and transparent properties. It is also widely used in many fields due to its excellent mechanical properties, wear resistance and chemical stability. However, it is flammable, has droplets, and produces harmful gases when burned, posing a significant risk to people's lives and property safety. PUR, or polyurethane, refers to a class of polymer compounds containing repeating carbamate units in the main chain. It is generally prepared by the reaction of polyvalent organic isocyanates and polyols. Based on the excellent performance of various polyurethane materials, its products have been widely used in both military and civilian industries, and have developed into an indispensable material in people's daily clothing, food, housing and transportation.

[0003] Flame retardants, also known as fire-resistant agents, are a class of compounds that act at multiple stages of the combustion process. They effectively prevent or slow combustion, thereby enhancing the fire resistance of polymer materials. Their mechanisms of action primarily include absorbing heat, forming a protective layer, and interrupting chemical reaction chains.

[0004] Halogen flame retardants can effectively reduce heat release during material combustion. However, such flame retardants will release a large amount of toxic gases such as hydrogen halide or organic halide during combustion, greatly increasing the amount of smoke released and the toxicity of the smoke, which is very detrimental to fire escape and the environment. Organophosphorus flame retardants can produce phosphorus volatiles during heating, which can effectively extinguish flames, but have poor stability and cause environmental pollution. Nitrogen-containing flame retardants have problems such as easy thermal decomposition during mixing and poor compatibility with elastomer materials.

[0005] Several methods can be used to improve the flame retardancy of materials. First, inhibit free radical reactions, for example by decomposing substances that can terminate polyurethane free radical reactions. Second, lower the system temperature, for example by allowing endothermic decomposition at or near the ignition temperature of rigid polyurethane foam to produce non-flammable substances. Third, reduce the concentration of combustible gases and dilute the concentration of oxygen in the environment, for example by allowing it to react with polyurethane degradation products to produce non-flammable gases.

[0006] The existing technologies currently have the following main problems: PET / PUR composite materials are flammable and halogen flame retardants are highly toxic. Summary of the Invention

[0007] In view of the above situation, in order to overcome the defects of the prior art, the present invention provides a flame-retardant PET / PUR composite material and a preparation method thereof. In order to solve the problems that the PET / PUR composite material is flammable and the toxicity of halogen flame retardants is high, the present invention proposes to prepare a nitrogen-silicon flame retardant by sequentially loading silica and an organic metal framework on carbon nanotubes, thereby realizing the integration of nitrogen-silicon flame retardant components and improving their dispersibility in the composite material. At the same time, polyurethane is modified with melamine polyphosphate, thereby achieving the technical effect of nitrogen-phosphorus-silicon synergistic flame retardancy.

[0008] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: The present invention proposes a flame-retardant PET / PUR composite material, which includes the following components in parts by weight: 16-20 parts of polyethylene terephthalate, 130-150 parts of modified polyurethane, and 1.3-1.6 parts of high-nitrogen synergistic flame retardant.

[0009] Preferably, the modified polyurethane is prepared with the following components by weight: 80-120 parts of polyether polyol, 100-130 parts of polymethylene polyphenyl polyisocyanate, 0.4-0.5 parts of dibutyltin dilaurate, 1.9-2.2 parts of silicone oil foam stabilizer, 0.8-1.2 parts of triethylenediamine, 2.6-3.1 parts of triethanolamine, 1.8-2 parts of water, and 0.8-1.1 parts of melamine polyphosphate.

[0010] Preferably, the preparation method of the modified polyurethane comprises the following steps:

[0011] (1) adding polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, silicone oil foam stabilizer, triethylenediamine, triethanolamine and water into a reactor and mixing them uniformly to obtain a mixture;

[0012] (2) Add melamine polyphosphate to the mixture, mix evenly, and then react in a water bath to obtain modified polyurethane.

[0013] Preferably, in step (2), the reaction is carried out in a water bath at a temperature of 80-90° C. for 8-10 h.

[0014] Preferably, the high nitrogen synergistic flame retardant is prepared with the following components by weight: 8-12 parts of carbon nanotubes, 65-70 parts of tetraethyl orthosilicate, 45-56 parts of zinc nitrate hexahydrate, 13-16 parts of 3-aminopropyltriethoxysilane, 52-59 parts of 2-methylimidazole, and 120-140 parts of 1,2,3-triazole.

[0015] Preferably, the preparation method of the high nitrogen synergistic flame retardant specifically comprises the following steps:

[0016] S1. Adding carbon nanotubes at an addition amount of 2-3 mg / mL to a mixture of sulfuric acid and nitric acid in a molar ratio of 3:1, stirring in a water bath, and then washing and drying to obtain acidified carbon nanotubes;

[0017] S2. Add the acidified carbon nanotubes obtained in S1 to anhydrous ethanol at an addition amount of 0.14-0.16 mg / mL, then add 10% ammonia water, mix well, add ethyl orthosilicate, stir for 10 hours, centrifuge to obtain the precipitate, wash, and dry to obtain modified carbon nanotubes;

[0018] S3, adding the modified carbon nanotubes obtained in S2 to a methanol solution at an addition amount of 0.12-0.14 mg / mL, adding zinc nitrate hexahydrate, ultrasonically dispersing for 0.5 h, adding 3-aminopropyltriethoxysilane, then stirring in a water bath, adding 2-methylimidazole, and standing at room temperature for 12 h to obtain a flame retardant;

[0019] S4. Add the flame retardant obtained in S3 to methanol at an addition amount of 1.2-1.6 mg / mL, add 1,2,3-triazole, ultrasonically disperse, then stir in a water bath, wash, and dry to obtain a high-nitrogen synergistic flame retardant.

[0020] Preferably, in S1, the water bath is stirred at a temperature of 55-65°C, a speed of 50-60 rpm, and a time of 2-3 h.

[0021] Preferably, in S2, the amount of 10% ammonia water added is 0.35-0.45 times the volume of anhydrous ethanol.

[0022] Preferably, in S3, the water bath is stirred at a temperature of 35-40°C, a speed of 100-120 rpm, and a time of 1.5-2.5 h.

[0023] Preferably, in S4, stirring is performed in a water bath at a temperature of 35-45° C., a speed of 40-60 rpm, and a time of 30-40 h.

[0024] The present invention also provides a method for preparing a flame retardant PET / PUR composite material, which specifically comprises the following steps:

[0025] The modified polyurethane and polyethylene terephthalate were dried at 80°C for 10 hours, and then a high-nitrogen synergistic flame retardant was added. The mixture was transferred to a high-speed mixer for mixing, and then poured into a twin-screw extruder for melt extrusion. Finally, the mixture was hot-pressed to obtain a flame-retardant PET / PUR composite material.

[0026] The beneficial effects achieved by the present invention are as follows: the present invention prepares nano-silicon dioxide on acidified nano-carbon tubes by using tetraethyl orthosilicate, and modifies the surface of the nano-carbon tubes with 3-aminopropyltriethoxysilane, adsorbs zinc ions on the surface of the modified nano-carbon tubes, and makes 2-methylimidazole in situ polymerize on the surface of the nano-carbon tubes to obtain a flame retardant, and increases the nitrogen content by using 1,2,3-triazole to obtain a high-nitrogen synergistic flame retardant, and at the same time modifies the polyurethane component with melamine polyphosphate, and mixes the modified polyurethane and polyethylene terephthalate with the high-nitrogen synergistic flame retardant to obtain a flame retardant containing nitrogen-phosphorus-silicon synergistic flame retardant. The flame-retardant PET / PUR composite material of the system; the high nitrogen component decomposes at high temperature to release non-combustible gases such as NH3 and N2, diluting the concentration of oxygen and combustible gases and exerting a gas-phase flame retardant effect. Silica forms a dense Si-OC carbon layer at 400-600℃, isolating heat and oxygen transfer, inhibiting further decomposition of the matrix and the phenomenon of droplet formation. Polyphosphoric acid catalyzes the dehydration of the polymer into carbon, generating a dense carbon layer to isolate heat and oxygen transfer. At the same time, polyphosphoric acid reacts with silica to form a silicophosphate glass layer, generating a nitrogen-expanded carbon layer. The silicon element strengthens the skeleton, further improving the flame retardant properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Graph showing thermal stability test results of the composite materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-3;

[0028] Figure 2 Graph showing smoke density test results of the composite materials prepared in Examples 1-3 of the present invention and Comparative Examples 1-3;

[0029] Figure 3 This is a graph showing the improvement in tensile strength of Examples 1-3.

[0030] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods and materials similar or equivalent to those described herein can be applied to the present invention. The preferred embodiments and materials described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0033] The experimental methods in the following examples are conventional methods unless otherwise specified; the experimental materials used in the following examples are purchased from commercial channels unless otherwise specified.

[0034] Example 1

[0035] A flame-retardant PET / PUR composite material comprises the following components in parts by weight: 16 parts of polyethylene terephthalate, 130 parts of modified polyurethane, and 1.3 parts of a high-nitrogen synergistic flame retardant.

[0036] The modified polyurethane was prepared with the following components by weight: 80 parts of polyether polyol, 100 parts of polymethylene polyphenyl polyisocyanate, 0.4 parts of dibutyltin dilaurate, 1.9 parts of silicone oil foam stabilizer, 0.8 parts of triethylenediamine, 2.6 parts of triethanolamine, 1.8 parts of water, and 0.8 parts of melamine polyphosphate.

[0037] The preparation method of modified polyurethane specifically comprises the following steps:

[0038] (1) adding polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, silicone oil foam stabilizer, triethylenediamine, triethanolamine and water into a reactor and mixing them uniformly to obtain a mixture;

[0039] (2) Melamine polyphosphate was added to the mixture, mixed evenly, and then reacted in a water bath at 80°C for 8 hours to obtain modified polyurethane.

[0040] The high nitrogen synergistic flame retardant is prepared with the following components by weight: 8 parts of carbon nanotubes, 65 parts of tetraethyl orthosilicate, 45 parts of zinc nitrate hexahydrate, 13 parts of 3-aminopropyltriethoxysilane, 52 parts of 2-methylimidazole, and 120 parts of 1,2,3-triazole.

[0041] The preparation method of the high nitrogen synergistic flame retardant specifically comprises the following steps:

[0042] S1. Adding carbon nanotubes at an addition amount of 2 mg / mL to a mixture of sulfuric acid and nitric acid in a molar ratio of 3:1, stirring at 50 rpm in a 55°C water bath for 2 h, then washing and drying to obtain acidified carbon nanotubes;

[0043] S2. The acidified carbon nanotubes obtained in S1 were added to anhydrous ethanol at a volume of 0.14 mg / mL, followed by the addition of 10 wt% ammonia water (0.35 times the volume of anhydrous ethanol), mixed well, and then added with tetraethyl orthosilicate. The mixture was stirred for 10 h, centrifuged, precipitated, washed, and dried to obtain modified carbon nanotubes.

[0044] S3, adding the modified carbon nanotubes obtained in S2 to a methanol solution at an addition amount of 0.12 mg / mL, adding zinc nitrate hexahydrate, ultrasonically dispersing for 0.5 h, adding 3-aminopropyltriethoxysilane, then stirring at 100 rpm in a 35°C water bath for 1.5 h, adding 2-methylimidazole, and standing at room temperature for 12 h to obtain a flame retardant;

[0045] S4. The flame retardant obtained in S3 was added to methanol at an addition amount of 1.2 mg / mL, 1,2,3-triazole was added, and ultrasonic dispersion was performed. Then, the mixture was stirred at 40 rpm in a 35°C water bath for 30 h, and the mixture was washed and dried to obtain a high-nitrogen synergistic flame retardant.

[0046] The present invention also provides a method for preparing a flame retardant PET / PUR composite material, which specifically comprises the following steps:

[0047] The modified polyurethane and polyethylene terephthalate were dried at 80°C for 10 hours, and then a high-nitrogen synergistic flame retardant was added. The mixture was transferred to a high-speed mixer for mixing, and then poured into a twin-screw extruder for melt extrusion. Finally, the mixture was hot-pressed to obtain a flame-retardant PET / PUR composite material.

[0048] Example 2

[0049] A flame-retardant PET / PUR composite material comprises the following components in parts by weight: 20 parts of polyethylene terephthalate, 150 parts of modified polyurethane, and 1.6 parts of a high-nitrogen synergistic flame retardant.

[0050] The modified polyurethane was prepared with the following components by weight: 120 parts of polyether polyol, 130 parts of polymethylene polyphenyl polyisocyanate, 0.5 parts of dibutyltin dilaurate, 2.2 parts of silicone oil foam stabilizer, 1.2 parts of triethylenediamine, 3.1 parts of triethanolamine, 2 parts of water, and 1.1 parts of melamine polyphosphate.

[0051] The preparation method of modified polyurethane specifically comprises the following steps:

[0052] (1) adding polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, silicone oil foam stabilizer, triethylenediamine, triethanolamine and water into a reactor and mixing them uniformly to obtain a mixture;

[0053] (2) Melamine polyphosphate was added to the mixture, mixed evenly, and then reacted in a water bath at 90°C for 10 h to obtain modified polyurethane.

[0054] The high nitrogen synergistic flame retardant is prepared with the following components by weight: 12 parts of carbon nanotubes, 70 parts of tetraethyl orthosilicate, 56 parts of zinc nitrate hexahydrate, 16 parts of 3-aminopropyltriethoxysilane, 59 parts of 2-methylimidazole, and 140 parts of 1,2,3-triazole.

[0055] The preparation method of the high nitrogen synergistic flame retardant specifically comprises the following steps:

[0056] S1. Adding 3 mg / mL of carbon nanotubes to a mixture of sulfuric acid and nitric acid in a molar ratio of 3:1, stirring at 60 rpm in a 65°C water bath for 2-3 hours, then washing and drying to obtain acidified carbon nanotubes;

[0057] S2. The acidified carbon nanotubes obtained in S1 were added to anhydrous ethanol at an addition amount of 0.16 mg / mL, followed by the addition of 10 wt% ammonia water (0.45 times the volume of anhydrous ethanol), mixed well, and then added with ethyl orthosilicate. The mixture was stirred for 10 h, centrifuged to obtain a precipitate, washed, and dried to obtain modified carbon nanotubes.

[0058] S3, adding the modified carbon nanotubes obtained in S2 to a methanol solution at an addition amount of 0.14 mg / mL, adding zinc nitrate hexahydrate, ultrasonically dispersing for 0.5 h, adding 3-aminopropyltriethoxysilane, then stirring at 120 rpm in a 40°C water bath for 2.5 h, adding 2-methylimidazole, and standing at room temperature for 12 h to obtain a flame retardant;

[0059] S4. The flame retardant obtained in S3 was added to methanol at an addition amount of 1.6 mg / mL, 1,2,3-triazole was added, and ultrasonic dispersion was performed. Then, the mixture was stirred at 60 rpm in a 45°C water bath for 40 h, and the mixture was washed and dried to obtain a high-nitrogen synergistic flame retardant.

[0060] The present invention also provides a method for preparing a flame retardant PET / PUR composite material, which specifically comprises the following steps:

[0061] The modified polyurethane and polyethylene terephthalate were dried at 80°C for 10 hours, and then a high-nitrogen synergistic flame retardant was added. The mixture was transferred to a high-speed mixer for mixing, and then poured into a twin-screw extruder for melt extrusion. Finally, the mixture was hot-pressed to obtain a flame-retardant PET / PUR composite material.

[0062] Example 3

[0063] A flame-retardant PET / PUR composite material comprises the following components in parts by weight: 18 parts of polyethylene terephthalate, 140 parts of modified polyurethane, and 1.5 parts of a high-nitrogen synergistic flame retardant.

[0064] The modified polyurethane is prepared with the following components by weight: 100 parts of polyether polyol, 120 parts of polymethylene polyphenyl polyisocyanate, 0.45 parts of dibutyltin dilaurate, 2 parts of silicone oil foam stabilizer, 1 part of triethylenediamine, 2.9 parts of triethanolamine, 1.9 parts of water, and 1 part of melamine polyphosphate.

[0065] The preparation method of modified polyurethane specifically comprises the following steps:

[0066] (1) adding polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, silicone oil foam stabilizer, triethylenediamine, triethanolamine and water into a reactor and mixing them uniformly to obtain a mixture;

[0067] (2) Melamine polyphosphate was added to the mixture, mixed evenly, and then reacted in a water bath at 85°C for 9 hours to obtain modified polyurethane.

[0068] The high nitrogen synergistic flame retardant is prepared with the following components by weight: 10 parts of carbon nanotubes, 68 parts of tetraethyl orthosilicate, 50 parts of zinc nitrate hexahydrate, 15 parts of 3-aminopropyltriethoxysilane, 54 parts of 2-methylimidazole, and 130 parts of 1,2,3-triazole.

[0069] The preparation method of the high nitrogen synergistic flame retardant specifically comprises the following steps:

[0070] S1. Adding carbon nanotubes at an addition amount of 2.5 mg / mL to a mixture of sulfuric acid and nitric acid in a molar ratio of 3:1, stirring at 55 rpm in a 60°C water bath for 2.5 h, then washing and drying to obtain acidified carbon nanotubes;

[0071] S2. The acidified carbon nanotubes obtained in S1 were added to anhydrous ethanol at a volume of 0.15 mg / mL, followed by the addition of 10 wt% ammonia water (0.4 times the volume of anhydrous ethanol), mixed well, and then added with tetraethyl orthosilicate. The mixture was stirred for 10 h, centrifuged, precipitated, washed, and dried to obtain modified carbon nanotubes.

[0072] S3, adding the modified carbon nanotubes obtained in S2 to a methanol solution at an addition amount of 0.13 mg / mL, adding zinc nitrate hexahydrate, ultrasonically dispersing for 0.5 h, adding 3-aminopropyltriethoxysilane, then stirring at 110 rpm in a water bath at 38°C for 2 h, adding 2-methylimidazole, and standing at room temperature for 12 h to obtain a flame retardant;

[0073] S4. The flame retardant obtained in S3 was added to methanol at an addition amount of 1.4 mg / mL, 1,2,3-triazole was added, and ultrasonic dispersion was performed. Then, the mixture was stirred at 50 rpm in a 40°C water bath for 35 h, and the mixture was washed and dried to obtain a high-nitrogen synergistic flame retardant.

[0074] The present invention also provides a method for preparing a flame retardant PET / PUR composite material, which specifically comprises the following steps:

[0075] The modified polyurethane and polyethylene terephthalate were dried at 80°C for 10 hours, and then a high-nitrogen synergistic flame retardant was added. The mixture was transferred to a high-speed mixer for mixing, and then poured into a twin-screw extruder for melt extrusion. Finally, the mixture was hot-pressed to obtain a flame-retardant PET / PUR composite material.

[0076] Comparative Example 1

[0077] This comparative example provides a composite material, which differs from Example 1 only in that the component does not contain tetraethyl orthosilicate, and the other components and component contents are the same as those in Example 1.

[0078] Comparative Example 2

[0079] This comparative example provides a composite material, which differs from Example 1 only in that the component does not contain 2-methylimidazole, and the other components and component contents are the same as those in Example 1.

[0080] Comparative Example 3

[0081] This comparative example provides a composite material, which differs from Example 1 only in that the component does not contain 3-aminopropyltriethoxysilane, and the other components and component contents are the same as those in Example 1.

[0082] Experimental example

[0083] 1. Thermal stability test

[0084] The thermal stability test was conducted on the samples prepared in Examples 1-3 and Comparative Examples 1-3 of the present invention using a thermogravimetric analyzer. The samples were heated from 30°C to 600°C in a nitrogen atmosphere at a heating rate of 30°C / min, and the weight residual rate was measured:

[0085] Weight residual rate = (weight after the experiment / weight before the experiment) × 100%.

[0086] Figure 1 This is a graph showing the thermal stability test results of the composite materials prepared by Examples 1-3 of the present invention and Comparative Examples 1-3. As shown in the figure, the weight residual rates of Examples 1-3 are 32.6%, 32.9%, and 33.5%, and the weight residual rates of Comparative Examples 1-3 are 20.6%, 24.5%, and 23.2%. The weight residual rates of Examples 1-3 are significantly higher than those of Comparative Examples 1-3, indicating that the use of tetraethyl orthosilicate, 2-methylimidazole, and 3-aminopropyltriethoxysilane significantly improves the thermal stability of the composite material.

[0087] 2. Smoke density test

[0088] The smoke density test was performed using a combustion smoke density tester. The composite materials obtained in Examples 1-3 and Comparative Examples 1-3 were prepared into block samples with a size of 25.4 mm × 25.4 mm × 6.0 mm. The samples were ignited with a butane flame, and the smoke density within 200 seconds was measured.

[0089] Figure 2The smoke density test results of the composite materials prepared by Examples 1-3 of the present invention and Comparative Examples 1-3 are shown in the figure. As shown in the figure, the smoke densities of Examples 1-3 are 12.2%, 13.5%, and 12.6%, and the smoke densities of Comparative Examples 1-3 are 21.2%, 26.3%, and 25.1%. The smoke density of Examples 1-3 is significantly lower than that of Comparative Examples 1-3, indicating that the use of tetraethyl orthosilicate, 2-methylimidazole, and 3-aminopropyltriethoxysilane significantly reduces the smoke density of the composite materials during combustion.

[0090] 3. Mechanical properties test

[0091] Mechanical properties were tested using a tensile testing machine. Examples 1-3 were used as the experimental group, and the composite material without the high-nitrogen synergistic flame retardant was used as the blank group. Five samples were taken for each sample, and the tensile strength was recorded each time. The average was taken as the tensile strength of the sample, and the tensile strength improvement rate was calculated using the following formula.

[0092] Tensile strength improvement rate = (tensile strength of experimental group / tensile strength of blank group) × 100%.

[0093] Figure 3 This is a result diagram of the tensile strength improvement rate of Examples 1-3. As shown in the figure, the tensile strength improvement rates of Examples 1-3 are 22.6%, 23.3%, and 23.5%; the tensile strength of Examples 1-3 is significantly improved compared with the tensile strength of the blank group, indicating that the use of high nitrogen synergistic flame retardant improves the tensile strength of the composite material.

[0094] While the embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the invention.

[0095] The present invention and its embodiments are described above. Such description is not restrictive. The drawings show only one embodiment of the present invention, and actual applications are not limited thereto. In short, if a person skilled in the art is inspired by the above, and does not deviate from the purpose of the present invention, any method and embodiment similar to the technical solution without creative design shall fall within the scope of protection of the present invention.

Claims

1. A flame retardant PET / PUR composite material, characterized by: The invention comprises the following components in parts by weight: 16-20 parts of polyethylene terephthalate, 130-150 parts of modified polyurethane, and 1.3-1.6 parts of high nitrogen synergistic flame retardant; The modified polyurethane is prepared from the following components by weight: 80-120 parts of polyether polyol, 100-130 parts of polymethylene polyphenyl polyisocyanate, 0.4-0.5 parts of dibutyltin dilaurate, 1.9-2.2 parts of silicone oil foam stabilizer, 0.8-1.2 parts of triethylenediamine, 2.6-3.1 parts of triethanolamine, 1.8-2 parts of water, and 0.8-1.1 parts of melamine polyphosphate; The high nitrogen synergistic flame retardant is prepared from the following components by weight: 8-12 parts of carbon nanotubes, 65-70 parts of tetraethyl orthosilicate, 45-56 parts of zinc nitrate hexahydrate, 13-16 parts of 3-aminopropyltriethoxysilane, 52-59 parts of 2-methylimidazole, and 120-140 parts of 1,2,3-triazole.

2. The method for preparing the flame-retardant PET / PUR composite material according to claim 1, wherein: The specific steps include: The modified polyurethane and polyethylene terephthalate were dried at 80°C for 10 hours, and then a high-nitrogen synergistic flame retardant was added. The mixture was transferred to a high-speed mixer for mixing, and then poured into a twin-screw extruder for melt extrusion. Finally, the mixture was hot-pressed to obtain a flame-retardant PET / PUR composite material.

3. The method for preparing the flame-retardant PET / PUR composite material according to claim 2, wherein: The preparation method of the high nitrogen synergistic flame retardant specifically comprises the following steps: S1. Adding carbon nanotubes at an addition amount of 2-3 mg / mL to a mixture of sulfuric acid and nitric acid in a molar ratio of 3:1, stirring in a water bath, and then washing and drying to obtain acidified carbon nanotubes; S2. Add the acidified carbon nanotubes obtained in S1 to anhydrous ethanol at an addition amount of 0.14-0.16 mg / mL, then add 10% ammonia water, mix well, add ethyl orthosilicate, stir for 10 hours, centrifuge to obtain the precipitate, wash, and dry to obtain modified carbon nanotubes; S3, adding the modified carbon nanotubes obtained in S2 to a methanol solution at an addition amount of 0.12-0.14 mg / mL, adding zinc nitrate hexahydrate, ultrasonically dispersing for 0.5 h, adding 3-aminopropyltriethoxysilane, then stirring in a water bath, adding 2-methylimidazole, and standing at room temperature for 12 h to obtain a flame retardant; S4. Add the flame retardant obtained in S3 to methanol at an addition amount of 1.2-1.6 mg / mL, add 1,2,3-triazole, ultrasonically disperse, then stir in a water bath, wash, and dry to obtain a high-nitrogen synergistic flame retardant.

4. The method for preparing the flame-retardant PET / PUR composite material according to claim 3, wherein: The preparation method of the modified polyurethane specifically comprises the following steps: (1) adding polyether polyol, polymethylene polyphenyl polyisocyanate, dibutyltin dilaurate, silicone oil foam stabilizer, triethylenediamine, triethanolamine and water into a reactor and mixing them uniformly to obtain a mixture; (2) Add melamine polyphosphate to the mixture, mix evenly, and then react in a water bath to obtain modified polyurethane.

5. The method for preparing the flame-retardant PET / PUR composite material according to claim 3, wherein: In S1, the water bath is stirred at a temperature of 55-65° C., a speed of 50-60 rpm, and a time of 2-3 h.

6. The method for preparing the flame-retardant PET / PUR composite material according to claim 5, characterized in that: In S2, the amount of 10% ammonia water added is 0.35-0.45 times the volume of anhydrous ethanol.

7. The method for preparing the flame-retardant PET / PUR composite material according to claim 6, wherein: In S3, the water bath is stirred at a temperature of 35-40°C, a speed of 100-120 rpm, and a time of 1.5-2.5 h.

8. The method for preparing the flame-retardant PET / PUR composite material according to claim 7, characterized in that: In S4, stir in a water bath at a temperature of 35-45°C, a speed of 40-60 rpm, and a time of 30-40 h.

9. The method for preparing the flame-retardant PET / PUR composite material according to claim 4, wherein: In step (2), the reaction is carried out in a water bath at a temperature of 80-90°C for 8-10 hours.

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