High-strength post-consumer recycled TPU / PET alloy material and its preparation method

Abstract

The present invention discloses a high-strength post-consumer recycled TPU / PET blend alloy material and a preparation method thereof. By mass, the raw material composition of the high-strength post-consumer recycled TPU / PET blend alloy material includes: 60-80 parts of post-consumer recycled TPU, 20-40 parts of post-consumer recycled PET, 3-10 parts of compatibilizer, and 0.03-0.1 part of acetate; the compatibilizer is obtained by reacting and polymerizing polyethylene terephthalate, adipic acid, and butanediol. The preparation method includes: mixing the post-consumer recycled TPU, post-consumer recycled PET, compatibilizer, and acetate, and adding them through the feeding port of a twin-screw extruder into the twin-screw extruder for melt extrusion to obtain the high-strength post-consumer recycled TPU / PET blend alloy material.

Description

Technical Field

[0001] The present invention relates to the technical field of TPU / PET blend alloy materials, and particularly relates to a high-strength post-consumer recycled TPU / PET blend alloy material and a preparation method thereof. Background Art

[0002] With the continuous progress of human society, the use of plastic products by people has also increased significantly. Therefore, a large amount of waste plastics have flooded into people's lives, polluting the land, air, and ocean. Millions of tons of plastics are ultimately buried and incinerated every year. Most plastic products are extremely difficult to degrade, and they will seriously pollute the atmosphere after incineration. The environmental problem is becoming increasingly serious, and people's awareness of environmental protection is also becoming stronger and stronger.

[0003] Thermoplastic polyurethane elastomer (TPU) is a type of polyurethane that can be plasticized by heating and has no or very few chemical cross-links in its chemical structure. It has high strength, high modulus, and rubber-like elasticity within a wide range of hardnesses and is widely used in the injection molding and extrusion fields. However, TPU will age and degrade after use, seriously affecting the performance of recycled materials.

[0004] Polybutylene terephthalate (PET) has good mechanical properties, solvent resistance, heat resistance, and good hygienic safety, and is widely used in the food packaging field. The performance of PET is relatively stable, and recycled materials still have high performance.

[0005] Blending recycled TPU and recycled PET can obtain an alloy with excellent performance. PET can endow the alloy with good mechanical properties, and using TPU as the matrix can ensure that the alloy has good elasticity. However, recycled TPU ages and degrades severely, with poor performance, and the melting points of the two differ greatly, and their compatibility is poor. Therefore, a certain compatibilizer needs to be introduced to make the two fully mixed in order to obtain a high-strength post-consumer recycled TPU / PET alloy.

[0006] The patent specification with the publication number CN 104419128 A discloses a recycled PET alloy and a preparation method thereof. Its components are proportioned by mass percentage as follows: 40% - 70% of PET recycled material, 10% - 40% of ABS, 15% - 25% of glass fiber, 3% - 10% of toughening agent, 2% - 8% of compatibilizer, 0.5% - 1% of lubricant, and 0.1% - 1% of antioxidant. This patented technology takes PET recycled material as the main body, uses ABS as the modified matrix, and adds glass fiber and toughening agent for modification, making a recycled PET alloy prepared thereby significantly improve the properties such as tensile strength, impact strength, elongation at break, and glow wire temperature of the PET recycled material. Among them, maleic anhydride grafted thermoplastic polyurethane rubber (TPU-g-MAH) used is used as a toughening agent, and the dosage is very small.

[0007] The patent specification with the publication number CN 114249977 A discloses a PET / TPU alloy material with excellent mechanical properties and its preparation method. The raw material composition of the alloy material includes PET, hydroxyl-terminated TPU, and a compatibilizer; based on the total mass of PET and hydroxyl-terminated TPU being 100%, the mass ratio of PET is 10% - 40%, and the mass ratio of hydroxyl-terminated TPU is 60% - 90%; the compatibilizer is an isocyanate group-terminated polyurethane, and the dosage is 2% - 10% of the total mass of PET and hydroxyl-terminated TPU. The preparation method includes: mixing PET and hydroxyl-terminated TPU into a uniform melt through the heating and shearing of a twin-screw in a reactive twin-screw extruder; feeding the compatibilizer into the reactive twin-screw extruder through a melt pump at the first exhaust port; after the melt and the compatibilizer are fully mixed and reacted under the action of the screw, they are extruded through a die head, and after water cooling, pelletizing, dehydration, and drying, a PET / TPU alloy material with excellent mechanical properties is obtained. Summary of the Invention

[0008] The present invention provides a high-strength post-consumer recycled TPU / PET blend alloy material, which adds a compatibilizer PEBAT made of specific raw materials and an acetate transesterification catalyst. On the one hand, the compatibilizer PEBAT contains both AA-EG (ethylene glycol)-BDO segments, making it have good compatibility with TPU, and also contains EG-PTA (terephthalic acid) segments, making it have good compatibility with PET. Therefore, the compatibility between TPU and PET is greatly improved during the blending process. On the other hand, during the melt blending process, the transesterification catalyst acetate can promote the transesterification reaction of a large number of ester bonds existing in TPU and PET, further improving the compatibility between TPU and PET.

[0009] The specific technical solutions are as follows:

[0010] A high-strength post-consumer recycled TPU / PET blend alloy material, in parts by mass, the raw material composition includes:

[0011]

[0012] The compatibilizer is obtained by the reaction polymerization of polyethylene terephthalate, adipic acid (AA), and butanediol (BDO).

[0013] The present invention uses acetate as a transesterification catalyst, which can still exhibit high catalytic efficiency at low addition amounts. The inventor has tried catalysts such as tetrabutyl titanate, dibutyltin oxide, dioctyltin oxide, and bismuth titanate. The results show that there is no catalytic effect at the low addition amounts of the present invention. Secondly, the above-mentioned tin / bismuth catalysts are prone to complex reactions with some additives such as some UV-resistant additives and some antioxidants, reducing the effect of the additives and showing obvious color reactions, affecting the performance and appearance of the material.

[0014] The melting points of PET and TPU differ greatly. Low-viscosity substances will weaken the screw shear, reducing the plasticizing ability of PET and causing unmelted materials or uneven dispersion. If the temperature is significantly increased to completely plasticize PET, TPU will degrade severely, affecting the material properties. Therefore, the compatibilizer PEBAT used in this invention is preferably a high-molecular substance with a number-average molecular weight of 40,000 - 120,000 g / mol, and its melt index is close to that of TPU, so it will not cause weakening of the screw shear.

[0015] Preferably, the number-average molecular weight of the compatibilizer is 40,000 - 120,000 g / mol, and the melt index under the conditions of 190°C and 5 kg pressure is 1 - 30 g / 10 min. If the molecular weight of the compatibilizer is too low and the melt index is too large, problems such as migration and precipitation will occur when added to the alloy. The melt viscosity is low, which will play a lubricating role during the screw extrusion process, reducing the screw shear and causing insufficient mixing of the PET and TPU alloy, resulting in problems such as unmelted materials. The compatibilizer of the present invention has, first, a structure similar to both PET and TPU, and second, there are also a large number of ester bonds in the compatibilizer, which can also undergo partial transesterification reactions with PET and TPU under the catalytic effect of acetate during processing to further improve compatibility.

[0016] In a preferred example, the preparation method of the compatibilizer includes: reacting polyethylene terephthalate, adipic acid, and butanediol at 140 - 280°C for 0.5 - 12 h, then evacuating, and reacting at 200 - 300°C and a vacuum degree of 100 - 500 Pa for 0.5 - 12 h to obtain the compatibilizer.

[0017] In a preferred example, in the compatibilizer, the ratio of the sum of the amounts of substance of adipic acid and terephthalic acid in polyethylene terephthalate to the amount of substance of butanediol is 1:1 - 2. Based on the sum of the amounts of substance of adipic acid and terephthalic acid in polyethylene terephthalate, the molar proportion of adipic acid does not exceed 90%.

[0018] In a preferred example, for the high-strength post-consumer recycled TPU / PET blend alloy material, the sum of the mass parts of the post-consumer recycled TPU and the post-consumer recycled PET is 100 parts.

[0019] The acetate preferably includes at least one of sodium acetate, potassium acetate, calcium acetate, magnesium acetate, and zinc acetate in the present invention.

[0020] The present invention also provides a method for preparing the high-strength post-consumer recycled TPU / PET alloy material, which includes: uniformly mixing post-consumer recycled TPU, post-consumer recycled PET, a compatibilizer, and acetate, and adding the mixture into a twin-screw extruder through a feeding port of the twin-screw extruder for melt extrusion to obtain the high-strength post-consumer recycled TPU / PET alloy material.

[0021] In a preferred example, in the preparation method, the post-consumer recycled TPU and the post-consumer recycled PET are granular materials with a particle size less than 5 mm.

[0022] In a preferred example, in the preparation method, both the feeding port and the exhaust port of the twin-screw extruder are protected by dry nitrogen.

[0023] In a preferred example, in the preparation method, the length-diameter ratio of the screw of the twin-screw extruder is 44-56:1.

[0024] In a preferred example, in the preparation method, the twin-screw extruder has 13 heating zones, and the temperatures of each zone from the feeding port to the head are as follows: the temperature of the first zone is 175-195 °C, the temperature of the second zone is 215-235 °C, the temperature of the third zone is 235-255 °C, the temperature of the fourth zone is 235-255 °C, the temperature of the fifth zone is 220-240 °C, the temperature of the sixth zone is 185-205 °C, the temperature of the seventh zone is 185-205 °C, the temperature of the eighth zone is 175-195 °C, the temperature of the ninth zone is 175-195 °C, the temperature of the tenth zone is 175-195 °C, the temperature of the eleventh zone is 175-195 °C, the temperature of the twelfth zone is 175-195 °C, and the temperature of the thirteenth zone is 220-240 °C.

[0025] In a preferred example, in the preparation method, the screw speed of the twin-screw extruder is 200-300 rpm.

[0026] In a preferred example, in the preparation method, after melt extrusion, it is subjected to strand pelletizing or underwater pelletizing, and then dried to obtain high-strength post-consumer recycled TPU / PET alloy material particles.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) In the compatibilizer PEBAT of the present invention, it contains both AA-EG (ethylene glycol)-BDO segments, making it have good compatibility with TPU, and also contains EG-PTA (terephthalic acid) segments, making it have good compatibility with PET. Therefore, during the blending process, the compatibility between TPU and PET is greatly improved.

[0029] 2) A large number of ester bonds exist in TPU, PET, and compatibilizer PEBAT. During the melt blending process, transesterification reactions will occur under the catalysis of a small amount of acetate, further improving their compatibility without affecting the color and appearance of the product.

[0030] 3) The introduction of the PET component can greatly improve the modulus, strength, and molding rate of the alloy, overcoming the problems of low modulus and low strength caused by severe degradation of recycled TPU. As the matrix, the TPU component can ensure that the alloy has good elasticity.

[0031] 4) This alloy is prepared from 100% post-consumer recycled materials, which are widely sourced and have excellent performance. It reprocesses and utilizes waste plastics in current society, reducing plastic pollution. Specific Embodiments

[0032] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0033] For the operation methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer.

[0034] Unless otherwise specified, the dosage "parts" of each component in the following examples and comparative examples all refer to parts by mass. The post-consumer recycled TPU is recycled waste TPU mobile phone cases, and the post-consumer recycled PET is recycled waste PET plastic bottles. The preparation method of the compatibilizer PEBAT is as follows: React ethylene glycol terephthalate, adipic acid, and butanediol at 220 °C for 4 h, then evacuate, and react at 220 °C and a vacuum degree of 300 Pa for 2 h to obtain the compatibilizer PEBAT. In the compatibilizer PEBAT, the ratio of the sum of the amounts of substance of adipic acid and terephthalic acid in ethylene glycol terephthalate to the amount of substance of butanediol is 1:1.6. Based on the sum of the amounts of substance of adipic acid and terephthalic acid in ethylene glycol terephthalate, the molar proportion of adipic acid is 40%. The number average molecular weight of the obtained compatibilizer PEBAT is 60000 g / mol, and the melt index at 190 °C and a pressure of 5 kg is 21.78 g / 10 min.

[0035] In the following embodiments and comparative examples, the twin-screw extruder has 13 heating zones, and the temperatures of the zones from the feed port to the die are: the temperature of zone 1 is 175-195°C, the temperature of zone 2 is 215-235°C, the temperature of zone 3 is 235-255°C, the temperature of zone 4 is 235-255°C, the temperature of zone 5 is 220-240°C, the temperature of zone 6 is 185-205°C, the temperature of zone 7 is 185-205°C, the temperature of zone 8 is 175-195°C, the temperature of zone 9 is 175-195°C, the temperature of zone 10 is 175-195°C, the temperature of zone 11 is 175-195°C, the temperature of zone 12 is 175-195°C, and the temperature of zone 13 is 220-240°C. The screw speed of the twin-screw extruder is 300rpm. The screw aspect ratio of the twin-screw extruder is 50:1. The feeding port and exhaust port of the twin-screw extruder are protected by dry nitrogen.

[0036] In the following embodiments and comparative examples, the hardness test adopts the standard ASTM D2240-2015, and the Shore A hardness tester is selected for testing; the tensile strength, 100% modulus and elongation at break are tested using the standard experimental method for tensile properties of vulcanized rubber and thermoplastic elastomer rubber GB-T 528-2009, wherein the gauge length is 25 mm, the tensile rate is 500 mm / min, and the test specimens are 5 dumbbell-shaped specimens with a thickness of 2±0.1 mm and a width of 6±0.1 mm, and the median value is taken; the above test environments are all carried out at 23±1°C and 50±5%RH.

[0037] Example 1

[0038] Weigh 0.06 parts of zinc acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0039] Place 3 parts of compatibilizer PEBAT and the above materials in a mixer and mix thoroughly, and feed the mixture into a twin-screw extruder through a feed port;

[0040] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain high-strength post-consumer recycled TPU / PET blend alloy material particles.

[0041] The post-consumer recycled TPU / PET blend alloy material prepared in this embodiment has a hardness of 95A, a tensile strength of 18.18 MPa, a 100% modulus of 17.19, and an elongation at break of 260.6%.

[0042] Example 2

[0043] Weigh 0.06 parts of zinc acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0044] Mix 6 parts of compatibilizer PEBAT with the above materials in a blender, and feed them into a twin-screw extruder through the feeding port;

[0045] After exiting the die head, it is pelletized by strand pelletizing and dried at 100 °C to obtain high-strength post-consumer recycled TPU / PET alloy material particles.

[0046] The post-consumer recycled TPU / PET alloy material prepared in this example has a hardness of 95A, a tensile strength of 20.09 MPa, a 100% modulus of 17.93, and an elongation at break of 304.22%.

[0047] Example 3

[0048] Weigh 0.06 parts of zinc acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size less than 5 mm;

[0049] Mix 9 parts of compatibilizer PEBAT with the above materials in a blender, and feed them into a twin-screw extruder through the feeding port;

[0050] After exiting the die head, it is pelletized by strand pelletizing and dried at 100 °C to obtain high-strength post-consumer recycled TPU / PET alloy material particles.

[0051] The post-consumer recycled TPU / PET alloy material prepared in this example has a hardness of 96A, a tensile strength of 23.57 MPa, a 100% modulus of 18.93, and an elongation at break of 331.5%.

[0052] Example 4

[0053] Weigh 0.06 parts of sodium acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size less than 5 mm;

[0054] Mix 9 parts of compatibilizer PEBAT with the above materials in a blender, and feed them into a twin-screw extruder through the feeding port;

[0055] After exiting the die head, it is pelletized by strand pelletizing and dried at 100 °C to obtain high-strength post-consumer recycled TPU / PET alloy material particles.

[0056] The post-consumer recycled TPU / PET alloy material prepared in this example has a hardness of 96A, a tensile strength of 22.3 MPa, a 100% modulus of 16.99, and an elongation at break of 315.7%.

[0057] Example 5

[0058] Weigh 0.06 parts of potassium acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0059] 9 parts of compatibilizer PEBAT and the above materials were placed in a mixer and mixed thoroughly, and then fed into a twin-screw extruder through a feeding port;

[0060] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain high-strength post-consumer recycled TPU / PET blend alloy material particles.

[0061] The post-consumer recycled TPU / PET blend alloy material prepared in this embodiment has a hardness of 96A, a tensile strength of 22.71 MPa, a 100% modulus of 18.21, and an elongation at break of 329.36%.

[0062] Example 6

[0063] Weigh 0.06 parts of calcium acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0064] 9 parts of compatibilizer PEBAT and the above materials were placed in a mixer and mixed thoroughly, and then fed into a twin-screw extruder through a feeding port;

[0065] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain high-strength post-consumer recycled TPU / PET blend alloy material particles.

[0066] The post-consumer recycled TPU / PET blend alloy material prepared in this embodiment has a hardness of 96A, a tensile strength of 23.93 MPa, a 100% modulus of 19.00, and an elongation at break of 343.2%.

[0067] Example 7

[0068] Weigh 0.06 parts of magnesium acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0069] 9 parts of compatibilizer PEBAT and the above materials were placed in a mixer and mixed thoroughly, and then fed into a twin-screw extruder through a feeding port;

[0070] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain high-strength post-consumer recycled TPU / PET blend alloy material particles.

[0071] The post-consumer recycled TPU / PET blend alloy material prepared in this embodiment has a hardness of 96A, a tensile strength of 22.86 MPa, a 100% modulus of 18.11, and an elongation at break of 337.2%.

[0072] Comparative Example 1

[0073] Weigh 0.06 parts of zinc acetate, 70 parts of post-consumer recycled TPU, and 30 parts of post-consumer recycled PET, place them in a mixer and mix them thoroughly, and feed them into a twin-screw extruder through a feed port; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0074] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain post-consumer recycled TPU / PET blend alloy material particles.

[0075] The post-consumer recycled TPU / PET blend alloy material prepared in this comparative example has a hardness of 95A, a tensile strength of 16.58 MPa, a 100% modulus of 15.46, and an elongation at break of 179.39%.

[0076] Comparative Example 2

[0077] Weigh 70 parts of post-consumer recycled TPU and 30 parts of post-consumer recycled PET, place them in a mixer and mix them thoroughly, and feed them into a twin-screw extruder through a feed port; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0078] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain post-consumer recycled TPU / PET blend alloy material particles.

[0079] The post-consumer recycled TPU / PET blend alloy material prepared in this comparative example has a hardness of 95A, a tensile strength of 14.36 MPa, a 100% modulus of 14.17, and an elongation at break of 117.35%.

[0080] Comparative Example 3

[0081] Weigh 70 parts of post-consumer recycled TPU, 30 parts of post-consumer recycled PET and 9 parts of compatibilizer PEBAT, place them in a mixer and mix them thoroughly, and feed them into a twin-screw extruder through a feed port; the post-consumer recycled TPU and post-consumer recycled PET are pre-crushed into particles with a particle size of less than 5 mm;

[0082] After exiting the die head, the pellets are drawn and granulated, and then dried at 100°C to obtain post-consumer recycled TPU / PET blend alloy material particles.

[0083] The post-consumer recycled TPU / PET alloy material prepared in this comparative example has a hardness of 95A, a tensile strength of 19.88 MPa, a 100% modulus of 16.11, and an elongation at break of 297.27%.

[0084] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A high-strength post-consumer recycled TPU / PET alloy material, characterized in that, The raw material composition, by mass parts, includes: The compatibilizer is obtained by the reaction polymerization of polyethylene terephthalate, adipic acid, and butanediol; The number-average molecular weight of the compatibilizer is 40,000 - 120,000 g / mol, and the melt index at 190 °C and a pressure of 5 kg is 1 - 30 g / 10 min; In the compatibilizer, the ratio of the sum of the amounts of substance of adipic acid and terephthalic acid in polyethylene terephthalate to the amount of substance of butanediol is 1:1 - 2. Based on the sum of the amounts of substance of adipic acid and terephthalic acid in polyethylene terephthalate, the molar proportion of adipic acid does not exceed 90%; The acetate salt includes at least one of sodium acetate, potassium acetate, calcium acetate, magnesium acetate, and zinc acetate.

2. The high-strength post-consumer recycled TPU / PET alloy material according to claim 1, wherein The preparation method of the compatibilizer includes: reacting polyethylene terephthalate, adipic acid, and butanediol at 140 - 280 °C for 0.5 - 12 h, then evacuating, and reacting at 200 - 300 °C and a vacuum degree of 100 - 500 Pa for 0.5 - 12 h to obtain the compatibilizer.

3. The high-strength post-consumer recycled TPU / PET alloy material according to claim 1, wherein The sum of the mass parts of the post-consumer recycled TPU and the post-consumer recycled PET is 100 parts.

4. The preparation method of the high-strength post-consumer recycled TPU / PET alloy material according to any one of claims 1-3, characterized in that, Includes: Mix the post-consumer recycled TPU, post-consumer recycled PET, compatibilizer, and acetate salt, and add them into a twin-screw extruder through the feeding port of the twin-screw extruder for melt extrusion to obtain a high-strength post-consumer recycled TPU / PET alloy material.

5. The preparation method according to claim 4, characterized in that, The post-consumer recycled TPU and the post-consumer recycled PET are particulate materials with a particle size less than 5 mm.

6. The preparation method according to claim 4, characterized in that, Both the feeding port and the exhaust port of the twin-screw extruder are protected by dry nitrogen; The length-diameter ratio of the screw of the twin-screw extruder is 44 - 56:1; The twin-screw extruder has 13 heating zones. The temperatures of each zone from the feeding port to the head are: the temperature of the first zone is 175 - 195 °C, the temperature of the second zone is 215 - 235 °C, the temperature of the third zone is 235 - 255 °C, the temperature of the fourth zone is 235 - 255 °C, the temperature of the fifth zone is 220 - 240 °C, the temperature of the sixth zone is 185 - 205 °C, the temperature of the seventh zone is 185 - 205 °C, the temperature of the eighth zone is 175 - 195 °C, the temperature of the ninth zone is 175 - 195 °C, the temperature of the tenth zone is 175 - 195 °C, the temperature of the eleventh zone is 175 - 195 °C, the temperature of the twelfth zone is 175 - 195 °C, and the temperature of the thirteenth zone is 220 - 240 °C; The screw speed of the twin-screw extruder is 200 - 300 rpm.

7. The preparation method according to claim 4, characterized in that, After melt extrusion, it is granulated by strand pelletizing or underwater pelletizing and dried to obtain high-strength post-consumer recycled TPU / PET alloy material pellets.

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