High-strength and high-flame-retardant TPU composite material and preparation method thereof

Abstract

The invention provides a high-strength and high-flame-retardant TPU composite material and a preparation method thereof, relates to the technical field of TPU composite materials, and aims to solve the problems that a traditional TPU material is inflammable and generates toxic smoke during combustion. The method comprises the following three main steps: S1, mixing TPU particles with a plurality of flame retardants and reinforcing materials, heating and stirring in a rotary drying and stirring tank, and preparing composite TPU particles through a twin-screw extruder; s2, the obtained particles are mixed with other auxiliaries, and the high-strength and high-flame-retardant TPU composite material is prepared after vacuum drying; s3, the high-strength and high-flame-retardant TPU composite material and the polyester yarn subjected to chemical treatment are heated and attached, and finally the high-strength and high-flame-retardant TPU composite material is obtained. According to the material, by adding the environment-friendly flame retardant and the reinforced fibers, the flame retardant property is remarkably improved, meanwhile, the elasticity and flexibility of TPU are kept, and the material has excellent mechanical properties and meets strict fireproof safety requirements.

Description

Technical Field

[0001] The invention relates to the technical field of TPU composite materials, in particular to a high-strength and high-flame-retardant TPU composite material and a preparation method thereof. Background Art

[0002] In the current field of TPU composite technology, thermoplastic polyurethane (TPU) is widely used in footwear, automobile, construction and electronics industries due to its excellent physical properties and processing convenience. However, pure TPU materials are flammable under high temperature conditions, and produce molten droplets and toxic smoke when burning, which limits its use in application scenarios with higher performance requirements. In order to improve the flame retardant properties of TPU, traditional methods usually involve adding halogen-containing flame retardants, but these additives produce toxic gases when burned, posing a serious threat to the environment and human health, and do not meet modern environmental protection requirements. Therefore, the development of a TPU composite material that is both environmentally friendly and has excellent flame retardant properties has become a research focus in this field.

[0003] In this context, researchers at home and abroad began to explore halogen-free, environmentally friendly flame retardants, such as phosphorus, nitrogen and metal hydroxides, to replace traditional halogen-containing flame retardants. At the same time, in order to further improve the mechanical properties of composite materials, reinforcing fibers are introduced into the TPU matrix, in order to obtain high-strength, high-wear-resistant composite materials through the synergistic effect of reinforcing fibers and TPU. These studies provide a theoretical basis and technical support for the development of halogen-free flame-retardant TPU composite materials. The present invention is based on such background technology, and aims to develop a new type of TPU composite material that meets flame retardant requirements and has high strength and high wear resistance through a combination of specific environmentally friendly flame retardants and reinforcing fibers, as well as a sophisticated preparation process, in order to achieve wider application in the fields of construction, industry, etc. The proposal of this scheme not only responds to the market demand for environmental protection and safety, but also provides a new direction for the technological progress and industrial upgrading of TPU composite materials. Summary of the invention

[0004] In view of the above problems, the present invention provides a high-strength and high-flame-retardant TPU composite material and a preparation method thereof.

[0005] To achieve the above objectives, the present invention is implemented by the following technical scheme: a high-strength and high-flame-retardant TPU composite material and a preparation method thereof, comprising the following steps:

[0006] S1: 90-100 parts of TPU particles, 10-15 parts of aluminum hypophosphite, 100-15 parts of ammonium polyphosphate, 7-10 parts of diethyl aluminum phosphite, 2-5 parts of ultra-high molecular weight polyethylene, 4-7 parts of phosphazene, 1-3 parts of expanded graphite and 1-3 parts of aramid fiber are put into a rotary drying stirring tank according to their mass proportions. After being stirred and heated at 55°C for 6 hours to ensure that all components are evenly mixed, they are sucked into a twin-screw extruder under negative pressure. After being continuously heated at 160-210°C to liquefy and flow, they are extruded, pulled and stretched into fine plastic strips through a 5 mm thick die hole. After being cooled, pelletized, screened, dehumidified and dried, composite TPU particles with high strength, high wear resistance and high flame retardancy are obtained.

[0007] S2: Put 150-180 parts of the composite TPU particles prepared in S1, 5-15 parts of masterbatch particles, 2-5 parts of ultraviolet absorbers, 1-2 parts of stabilizers, 0.1-0.3 parts of antioxidants, and 3-6 parts of hydrolysis resistance agents into a vacuum dryer according to their mass proportions, and heat and dehydrate at 75°C. The dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, and after heating and mixing evenly, it flows into a T-die and flows out from the lip gap of the T-die. The fluid is rolled into a film, and then rolled up after embossing, cooling, trimming, and obtaining a high-strength and high-flame-retardant TPU composite material.

[0008] Preferably, the molecular weight of the ultra-high molecular weight polyethylene is between 2 million and 4 million.

[0009] The ultra-high molecular weight polyethylene has excellent wear resistance and impact resistance due to its large molecular weight. When blended with TPU, the wear resistance and impact resistance of TPU can be improved while maintaining the elasticity and flexibility of TPU.

[0010] Preferably, the heat stabilizer is zinc stearate.

[0011] The zinc stearate acts as a heat stabilizer to prevent thermal degradation of TPU during processing and maintain stable performance of the material.

[0012] Preferably, the antioxidant is bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite.

[0013] Preferably, the anti-hydrolysis agent is any one of phenyl glycidyl ether and tetrakis(phenyl glycidyl ether)ethane.

[0014] Preferably, the polyester yarn is a polyester yarn with a linear density of 1000D.

[0015] Preferably, the mass ratio of deionized water, anhydrous ethanol and tetrahydrofuran in the mixed solution of deionized water, anhydrous ethanol and tetrahydrofuran is 5:2:1.

[0016] Preferably, the weight ratio of the polyester yarn, tetrabutyl titanate and the mixed solution of ionized water, anhydrous ethanol and tetrahydrofuran is 5-7:1:16-20.

[0017] The aluminum hypophosphite, ammonium polyphosphate and aluminum diethylphosphinate are used as flame retardants, which react chemically with TPU particles during heat treatment to form phosphorus-carbon bonds, thereby enhancing the flame retardant properties of TPU. These phosphorus-containing compounds decompose at high temperatures to produce phosphoric acid, thereby forming a carbon layer on the surface of the material, isolating oxygen and heat, and improving the flame retardant effect of the material; expanded graphite can be used as a flame retardant and heat insulation reinforcement material for TPU due to its rapid expansion at high temperatures; under high temperature conditions, expanded graphite can form a dense carbon layer, isolating heat and oxygen, and improving the flame retardant properties of TPU; phosphazene, as a flame retardant, can react chemically with TPU particles to further enhance the flame retardant properties of TPU; nitrogen and phosphorus compounds produced by the decomposition of phosphazene can promote the formation of a carbon layer and improve the flame retardant effect of the material; under the synergistic effect of aluminum hypophosphite, ammonium polyphosphate, aluminum diethylphosphinate, phosphazene and expanded graphite, a dense carbon layer is formed to isolate oxygen and heat, thereby enhancing the fireproof and heat insulation properties of the TPU material.

[0018] The aramid fiber has the characteristics of high strength and high modulus. When blended with TPU, it can significantly improve the mechanical properties of the composite material, and improve the strength and wear resistance of the material. The glass transition temperature of the aramid fiber is about 275°C, the thermal decomposition temperature is between 400 and 430°C, and no melting droplets occur in the flame; when the aramid fiber is heated to above 400°C, it begins to carbonize and form a tough coke layer. Beneficial Effects

[0019] The present invention provides a high-strength and high-flame-retardant TPU composite material and a preparation method thereof. It has the following beneficial effects:

[0020] 1. The high-strength and high-flame-retardant TPU composite material prepared by the present invention significantly improves the flame retardant properties of the material by adding flame retardants such as aluminum hypophosphite, ammonium polyphosphate, aluminum diethylphosphinate, phosphazene and expanded graphite. These flame retardants react chemically with TPU particles during heat treatment to form phosphorus-carbon bonds and carbon layers, effectively isolating oxygen and heat, improving the flame retardant effect of the material, and enabling the composite material to reach V-0 flame retardant grade and meet strict fire safety requirements.

[0021] 2. The high-strength and high-flame-retardant TPU composite material prepared by the present invention has excellent mechanical properties while maintaining the elasticity and flexibility of TPU, which makes the material have better durability and reliability in practical applications. DETAILED DESCRIPTION

[0022] 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.

[0023] Embodiment 1:

[0024] A method for preparing a high-strength and high-flame-retardant TPU composite material comprises the following steps:

[0025] S1: 95 parts of TPU particles, 12 parts of aluminum hypophosphite, 12 parts of ammonium polyphosphate, 8 parts of diethyl aluminum phosphite, 3 parts of ultra-high molecular weight polyethylene, 5 parts of phosphazene, 2 parts of expanded graphite and 2 parts of aramid fiber are put into a rotary drying stirring tank according to their mass proportions. After being stirred and heated at 55°C for 6 hours to ensure that all components are evenly mixed, they are sucked into a twin-screw extruder under negative pressure. After being continuously heated at 160-210°C to liquefy and flow, they are extruded, pulled and stretched into fine plastic strips through a 5mm thick die hole. After being cooled, pelletized, screened, dehumidified and dried, composite TPU particles with high strength, high wear resistance and high flame retardancy are obtained.

[0026] S2: 165 parts of the composite TPU particles prepared in S1, 10 parts of masterbatch particles, 3 parts of ultraviolet absorbers, 1.5 parts of stabilizers, 0.2 parts of antioxidants and 4.5 parts of hydrolysis resistance agents are put into a vacuum dryer according to their mass proportions, heated and vacuum dehydrated at 75°C. The dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, heated and mixed evenly, and then flows into a T-die, flows out from the lip gap of the T-die, and the fluid is rolled into a film, which is then embossed, cooled, trimmed, and rolled up to obtain a high-strength and high-flame-retardant TPU composite material.

[0027] Embodiment 2:

[0028] A method for preparing a high-strength and high-flame-retardant TPU composite material comprises the following steps:

[0029] S1: 90 parts of TPU particles, 10 parts of aluminum hypophosphite, 10 parts of ammonium polyphosphate, 7 parts of diethyl aluminum phosphite, 2 parts of ultra-high molecular weight polyethylene, 4 parts of phosphazene, 1 part of expanded graphite and 1 part of aramid fiber are put into a rotary drying stirring tank, stirred and heated at 55°C for 6 hours to ensure that all components are evenly mixed, and then sucked into a twin-screw extruder under negative pressure. After continuous heating and liquefaction at 160-210°C, they are extruded, pulled and stretched into fine plastic strips through a 5mm thick die hole. After cooling, pelletizing, screening, dehumidification and drying, composite TPU particles with high strength, high wear resistance and high flame retardancy are obtained.

[0030] S2: 150 parts of the composite TPU particles prepared in S1, 5 parts of masterbatch particles, 2 parts of ultraviolet absorbers, 1 part of stabilizers, 0.1 parts of antioxidants and 3 parts of hydrolysis resistance agents are put into a vacuum dryer according to their mass proportions for heating and vacuum dehydration at 75°C. The dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, and after being heated and mixed evenly, it flows into a T-die and flows out from the lip gap of the T-die. The fluid is rolled into a film, and then rolled up after embossing, cooling and trimming to obtain a high-strength and high-flame-retardant TPU composite material.

[0031] Embodiment 3:

[0032] A method for preparing a high-strength and high-flame-retardant TPU composite material comprises the following steps:

[0033] S1: 100 parts of TPU particles, 15 parts of aluminum hypophosphite, 15 parts of ammonium polyphosphate, 10 parts of diethyl aluminum phosphite, 5 parts of ultra-high molecular weight polyethylene, 7 parts of phosphazene, 3 parts of expanded graphite and 3 parts of aramid fiber are put into a rotary drying stirring tank, stirred and heated at 55°C for 6 hours to ensure that all components are evenly mixed, and then sucked into a twin-screw extruder under negative pressure. After continuous heating and liquefaction at 160-210°C, they are extruded, pulled and stretched into fine plastic strips through a 5mm thick die hole. After cooling, pelletizing, screening, dehumidification and drying, composite TPU particles with high strength, high wear resistance and high flame retardancy are obtained.

[0034] S2: 180 parts of the composite TPU particles prepared in S1, 15 parts of masterbatch particles, 5 parts of ultraviolet absorbers, 2 parts of stabilizers, 0.3 parts of antioxidants and 6 parts of hydrolysis resistance agents are put into a vacuum dryer according to their mass proportions, heated and vacuum dehydrated at 75°C. The dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, heated and mixed evenly, and then flows into a T-die, flows out from the lip gap of the T-die, and the fluid is rolled into a film, which is then embossed, cooled, trimmed, and rolled up to obtain a high-strength and high-flame-retardant TPU composite material.

[0035] Embodiment 4:

[0036] A method for preparing a high-strength and high-flame-retardant TPU composite material comprises the following steps:

[0037] S1: 95 parts of TPU particles, 13 parts of aluminum hypophosphite, 13 parts of ammonium polyphosphate, 8.5 parts of diethyl aluminum phosphite, 4 parts of ultra-high molecular weight polyethylene, 6 parts of phosphazene, 2.5 parts of expanded graphite and 2.5 parts of aramid fiber were put into a rotary drying stirring tank, stirred and heated at 55°C for 6 hours to ensure that all components were evenly mixed, and then sucked into a twin-screw extruder under negative pressure. After continuous heating and liquefaction at 160-210°C, they were extruded, pulled and stretched into fine plastic strips through a 5mm thick die hole. After cooling, pelletizing, screening, dehumidification and drying, composite TPU particles with high strength, high wear resistance and high flame retardancy were obtained.

[0038] S2: 165 parts of the composite TPU particles prepared in S1, 10 parts of masterbatch, 3.5 parts of UV absorber, 1.75 parts of stabilizer, 0.25 parts of antioxidant and 4.75 parts of hydrolysis resistance agent are put into a vacuum dryer according to their mass proportions, heated and dehydrated at 75°C, and the dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, heated and mixed evenly, and then flows into a T-die, flows out from the lip gap of the T-die, and the fluid is rolled into a film, and then rolled up after embossing, cooling, trimming, and obtaining a high-strength and high-flame-retardant TPU composite material.

[0039] Embodiment 5:

[0040] A method for preparing a high-strength and high-flame-retardant TPU composite material comprises the following steps:

[0041] S1: 92 parts of TPU particles, 11 parts of aluminum hypophosphite, 11 parts of ammonium polyphosphate, 8 parts of diethyl aluminum phosphite, 3 parts of ultra-high molecular weight polyethylene, 5 parts of phosphazene, 2 parts of expanded graphite, and 2 parts of aramid fiber; put them into a rotary drying stirring tank, stir and heat at 55°C for 6 hours to ensure that all components are evenly mixed, and then suck them into a twin-screw extruder under negative pressure, and after continuous heating at 160-210°C to liquefy and flow, they are extruded, pulled and stretched into fine plastic strips through a 5mm thick die hole, and after cooling, pelletizing, screening, dehumidification and drying, composite TPU particles with high strength, high wear resistance and high flame retardancy are obtained.

[0042] S2: 155 parts of the composite TPU particles prepared in S1, 7 parts of masterbatch particles, 2.5 parts of ultraviolet absorbers, 1.25 parts of stabilizers, 0.15 parts of antioxidants and 3.5 parts of hydrolysis resistance agents are put into a vacuum dryer according to their mass proportions, heated and dehydrated at 75°C. The dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, heated and mixed evenly, and then flows into a T-die, flows out from the lip gap of the T-die, and the fluid is rolled into a film, which is then embossed, cooled, trimmed, and rolled up to obtain a high-strength and high-flame-retardant TPU composite material.

[0043] Embodiment 6:

[0044] A method for preparing a high-strength and high-flame-retardant TPU composite material comprises the following steps:

[0045] S1: 98 parts of TPU particles, 14 parts of aluminum hypophosphite, 14 parts of ammonium polyphosphate, 9 parts of diethyl aluminum phosphite, 4 parts of ultra-high molecular weight polyethylene, 6 parts of phosphazene, 2.8 parts of expanded graphite, and 2.5 parts of aramid fiber; put them into a rotary drying stirring tank, stir and heat at 55°C for 6 hours to ensure that all components are evenly mixed, and then suck them into a twin-screw extruder under negative pressure, and after continuous heating at 160-210°C to liquefy and flow, they are extruded, pulled and stretched into fine plastic strips through a 5mm thick die hole, and after cooling, pelletizing, screening, dehumidification and drying, composite TPU particles with high strength, high wear resistance and high flame retardancy are obtained.

[0046] S2: 175 parts of the composite TPU particles prepared in S1, 12 parts of masterbatch particles, 4 parts of ultraviolet absorbers, 1.8 parts of stabilizers, 0.3 parts of antioxidants and 5 parts of hydrolysis resistance agents are put into a vacuum dryer according to their mass proportions for heating and vacuum dehydration at 75°C. The dew point needs to reach below -20DP before subsequent processing can begin. After drying, the mixture is sent to a screw extruder, and after being heated and mixed evenly, it flows into a T-die and flows out from the lip gap of the T-die. The fluid is rolled into a film, and then rolled up after embossing, cooling and trimming to obtain a high-strength and high-flame-retardant TPU composite material.

[0047] Comparative Example 1:

[0048] In Comparative Example 1, except that no expanded graphite was added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those of Example 1.

[0049] Comparative Example 2:

[0050] In Comparative Example 2, except that no ammonium polyphosphate was added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those in Example 1.

[0051] Comparative Example 3:

[0052] In Comparative Example 3, except that aramid fiber was not added, the rest of the raw material ratios, preparation methods, and operating conditions were the same as those in Example 1.

[0053] The high-strength and high-flame-retardant TPU composite materials prepared in Examples 1-6 and Comparative Examples 1-3 were subjected to tensile strength test (GBT528-2009), elongation at break (T529-2008), flame retardancy grade (GB / T2408-2008), oxygen index test (GB / T2406), and dripping test (GB / T 8626). The detailed results are shown in Table 1:

[0054] Table 1

[0055] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-strength and high-flame-retardant TPU composite material, characterized in that: The steps include: S1: 90-100 parts of TPU particles, 10-15 parts of aluminum hypophosphite, 100-15 parts of ammonium polyphosphate, 7-10 parts of diethyl aluminum phosphite, 2-5 parts of ultra-high molecular weight polyethylene, 4-7 parts of phosphazene, 1-3 parts of expanded graphite, and 1-3 parts of aramid fiber are put into a rotary drying stirring tank according to the mass fraction, and after being stirred and heated at 55°C for 6 hours, the mixture is sucked into a twin-screw extruder under negative pressure, and after being continuously heated at 160-210°C and liquefied and flowed, the mixture is extruded, pulled, and stretched into fine plastic strips through a 5mm thick die hole, and after being cooled, pelletized, screened, dehumidified, and dried, composite TPU particles with high strength, high wear resistance, and high flame retardancy are obtained; S2: 150-180 parts of the composite TPU particles prepared in S1, 5-15 parts of masterbatch particles, 2-5 parts of ultraviolet absorbers, 1-2 parts of stabilizers, 0.1-0.3 parts of antioxidants, and 3-6 parts of hydrolysis resistance agents are put into a dryer according to their mass proportions, heated and vacuum dehydrated at 75°C, and the dew point needs to reach below -20DP before subsequent processing can begin; after drying, the extruder is sent to a screw extruder, and after heating and mixing evenly, it flows into a T-die, and flows out from the lip gap of the T-die. The fluid is rolled into a film, and then rolled up after embossing, cooling, trimming, and obtaining a high-strength and high-flame-retardant TPU composite material.

2. The method for preparing a high-strength and high-flame-retardant TPU composite material according to claim 1, characterized in that: The molecular weight of the ultra-high molecular weight polyethylene is between 2 million and 4 million.

3. The method for preparing a high-strength and high-flame-retardant TPU composite material according to claim 1, characterized in that: The heat stabilizer is zinc stearate.

4. The method for preparing a high-strength and high-flame-retardant TPU composite material according to claim 1, characterized in that: The antioxidant is bis(2.4-di-tert-butylphenyl)pentaerythritol diphosphite.

5. The method for preparing a high-strength and high-flame-retardant TPU composite material according to claim 1, characterized in that: The anti-hydrolysis agent is any one of phenyl glycidyl ether and tetrakis(phenyl glycidyl ether)ethane.

6. The method for preparing a high-strength and high-flame-retardant TPU composite material according to claim 1, characterized in that: The polyester yarn is a polyester yarn with a linear density of 1000D.

7. A high-strength and high-flame-retardant TPU composite material, characterized in that: The high-strength and high-flame-retardant TPU composite material is obtained by the preparation method of any one of claims 1 to 6.

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