Novel TPU film

Abstract

The invention relates to the field of TPU (thermoplastic polyurethane) films, in particular to a novel TPU film which is prepared from the following raw materials in parts by mass: 60-80 parts of TPU raw material particles with the shore hardness of 85A, 50-70 parts of modified nitrile rubber, 3-7 parts of modified nano silicon dioxide, 2-3 parts of hollow glass beads and the like. Efficient compounding and interface fusion of TPU and a rubber material are achieved on the molecular level, functional filler is introduced to optimize the processability, compared with the prior art, the production cost is remarkably reduced, meanwhile, the mechanical strength, wear resistance and forming quality of the film are greatly improved, the problems that a traditional material is poor in compatibility and performance is degraded are solved, and the application prospect is wide. Wide application prospects are realized in the fields of high-end packaging, industrial protection, special composite materials and the like.

Description

Technical Field

[0001] This invention relates to the field of TPU films, and more particularly to a novel TPU film. Background Technology

[0002] Thermoplastic polyurethane (TPU) film is a high-molecular functional material made from TPU particles through processes such as casting. Its molecular chains are usually arranged linearly. Due to its excellent elasticity, abrasion resistance, cold resistance and high tensile strength, TPU film is widely used in many fields such as clothing bonding, inflatable products, medical devices, automotive interiors and electronic product protection.

[0003] In existing technologies, TPU films are mainly produced directly from pure TPU particles through a casting process. Due to the linear arrangement of TPU molecules and its inert nature, it has poor affinity with other materials, which limits its application range. Furthermore, the polyols in TPU are mainly derived from petroleum, resulting in persistently high raw material costs. In order to cope with cost pressures, the market has tried adding recycled TPU materials during the casting process. However, TPU materials are prone to performance degradation after repeated high-temperature processing, which seriously affects the performance indicators of the final film product.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a new type of TPU film. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a novel TPU film to solve the problems of high cost, poor compatibility, performance degradation and insufficient oil resistance in the prior art.

[0006] To achieve the above objectives, the present invention provides a novel TPU film.

[0007] A novel TPU film is composed of the following components in parts by weight: 60-80 parts of TPU raw material particles with a Shore hardness of 85A, 50-70 parts of modified nitrile rubber, 3-7 parts of modified nano-silica, 2-3 parts of hollow glass microspheres, 15-25 parts of 1,4-butanediol, and 5-10 parts of modified TPU-based prepolymer. The modified nitrile rubber is a nitrile rubber with high acrylonitrile content; The modified nano-silica is nano-silica with surface modification by silane coupling agent KH-550; The modified TPU-based prepolymer is an isocyanate-terminated TPU-based prepolymer.

[0008] Preferably, the preparation steps of the modified nitrile rubber are as follows: Butadiene, potassium disproportionated rosinate soap as emulsifier, acrylonitrile, and tert-dodecyl mercaptan are added to deionized water, heated to 20-30℃, rotated at 60-80 rpm, and emulsified for 50-70 minutes. The temperature is then raised to 35-45℃, potassium persulfate as initiator is added, and the reaction is carried out for 10-12 hours. Sodium dimethyl dithiocarbamate as terminator is added. Once the reaction is complete, impurities are removed, the mixture is washed, dehydrated, and dried to obtain modified nitrile rubber.

[0009] By introducing lower-priced nitrile rubber to partially replace TPU and utilizing its inherent oil and abrasion resistance, the raw material cost is directly reduced while ensuring performance. At the same time, the composite modification strategy effectively avoids the performance degradation problem caused by the use of recycled materials, achieving a balance between low cost and high performance.

[0010] Preferably, the mass ratio of butadiene, emulsifier, acrylonitrile, tert-dodecyl mercaptan, initiator and terminator is 1:0.04-0.06:0.65-0.67:0.0065-0.0067:0.004-0.006:0.0015-0.0017.

[0011] Preferably, the preparation steps of the modified nano-silica are as follows: Step A1: Add silica to anhydrous ethanol, stir at 400-600 rpm for 20-40 min, increase the speed to 8000-10000 rpm, and shear disperse for 30-40 min to obtain a suspension; Step A2: Add the hydrolysate of silane coupling agent KH-550 to the suspension, heat to 55-65℃, rotate at 300-500 rpm, reflux for 4-6 hours. After the reaction is complete, cool to 20-30℃, filter and dry, pulverize and sieve to obtain modified nano-silica.

[0012] The combined use of modified nano-silica and hollow glass microspheres effectively adjusts the melt index of the blend system, stabilizing it within a range suitable for casting. During the casting process, the system maintains stable pre-cast pressure and uniform melt flow, significantly reducing surface defects such as crystal points and bubbles, and improving the film forming quality, surface smoothness, and yield.

[0013] Preferably, the mass ratio of silicon dioxide to anhydrous ethanol in step A1 is 1:3.8-4.2.

[0014] Preferably, the mass ratio of the hydrolysate to the suspension in step A2 is 0.12-0.15:1.

[0015] Preferably, the preparation steps of the modified TPU-based prepolymer are as follows: Under a nitrogen atmosphere, 4,4'-diphenylmethane diisocyanate was added to poly(1,4-butanediol adipate), the temperature was raised to 55-65°C, the rotation speed was 150-250 rpm, dibutyltin dilaurate was added as a catalyst, the temperature was raised to 75-85°C, and the reaction was carried out for 2-3 hours. After the reaction was completed, the temperature was lowered to 20-30°C to obtain the modified TPU-based prepolymer.

[0016] Since the isocyanate-terminated TPU prepolymer acts as a macromolecular chain extender, it generates a "TPU-g-NBR" graft copolymer in situ in the system, which greatly improves the interfacial compatibility between the two phases. At the same time, the nano-silica modified with silane coupling agent KH-550 is firmly bonded to the polymer matrix through chemical bonding, resulting in a significant synergistic enhancement effect.

[0017] Preferably, the mass ratio of 4,4'-diphenylmethane diisocyanate, poly(1,4-butanediol adipate) to catalyst is 1:4.54-4.55:0.0013-0.0014.

[0018] Preferably, the specific preparation steps are as follows: Step S1: Add TPU particles with a Shore hardness of 85A, modified nitrile rubber, modified nano silica, hollow glass microspheres, 1,4-butanediol and modified TPU-based prepolymer to a high-speed mixer, heat to 180-200℃, rotate at 300-400 rpm, mix for 3-5 minutes, reduce pressure to -0.08 to -0.1 MPa, react for 2-3 minutes, after the reaction is complete, cool to 20-30℃ to obtain modified TPU composite particles; Step S2: Add the modified TPU composite particles into a single-screw casting machine, set the pre-cast pressure to 7-12 kPa, heat to 80-100℃, dry for 3-4 hours, with screw zone 1 at 180-190℃, screw zone 2 at 185-195℃, screw zone 3 at 190-200℃, screw speed at 40-60 rpm, front roller at 25-35℃, middle roller at 40-50℃, rear roller at 20-30℃, and cool to crystallize at 8-12℃ to obtain a novel TPU film.

[0019] Preferably, the particle size of the hollow glass microspheres is 10-50 μm.

[0020] The beneficial effects of this invention are: This invention provides a novel TPU film. By employing a special composite additive and modified material system, this invention achieves efficient composite and interfacial fusion of TPU and rubber materials at the molecular level, and introduces functional fillers to optimize processing performance. Compared with existing technologies, this invention significantly reduces production costs while greatly improving the mechanical strength, wear resistance, and molding quality of the film. It solves the problems of poor compatibility and performance degradation of traditional materials, and has broad application prospects in high-end packaging, industrial protection, and special composite materials. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0022] Example 1: Preparation of a modified nitrile rubber.

[0023] 100g of butadiene, 4g of emulsifier potassium disproportionated rosinate soap, 65g of acrylonitrile, and 0.65g of tert-dodecyl mercaptan were added to 200mL of deionized water. The mixture was heated to 20℃, rotated at 80rpm, and emulsified for 50min. The temperature was then raised to 45℃, and 0.4g of initiator potassium persulfate was added. The reaction was allowed to proceed for 10h. Finally, 0.15g of terminator sodium dimethyl dithiocarbamate was added. Once the reaction was complete, impurities were removed, the mixture was washed, dehydrated, and dried to obtain modified nitrile rubber.

[0024] Example 2: Preparation of a modified nitrile rubber.

[0025] 100g of butadiene, 5g of emulsifier potassium disproportionated rosinate soap, 66g of acrylonitrile, and 0.66g of tert-dodecyl mercaptan were added to 200mL of deionized water. The mixture was heated to 25℃, rotated at 70rpm, and emulsified for 60min. The temperature was then raised to 40℃, and 0.5g of initiator potassium persulfate was added. The reaction was allowed to proceed for 11h. Finally, 0.16g of terminator sodium dimethyl dithiocarbamate was added. Once the reaction was complete, impurities were removed, the mixture was washed, dehydrated, and dried to obtain modified nitrile rubber.

[0026] Example 3: Preparation of a modified nitrile rubber.

[0027] 100g of butadiene, 6g of emulsifier potassium disproportionated rosinate soap, 67g of acrylonitrile, and 0.67g of tert-dodecyl mercaptan were added to 200mL of deionized water. The mixture was heated to 30℃, rotated at 60rpm, and emulsified for 70min. The temperature was then raised to 35℃, and 0.6g of initiator potassium persulfate was added. The reaction was allowed to proceed for 12h. Finally, 0.17g of terminator sodium dimethyl dithiocarbamate was added. Once the reaction was complete, impurities were removed, the mixture was washed, dehydrated, and dried to obtain modified nitrile rubber.

[0028] Example 4: Preparation of a modified nano-silica S1: Add 100g of silica to 380g of anhydrous ethanol, stir at 400rpm for 40min, increase the speed to 8000rpm, and shear disperse for 40min to obtain a suspension. S2: Add 12g of silane coupling agent KH-550 hydrolysate to 100g of suspension, heat to 55℃, rotate at 500rpm, reflux for 4h, after the reaction is complete, cool to 30℃, filter, dry, pulverize and sieve to obtain modified nano silica.

[0029] Example 5: Preparation of a modified nano-silica S1: Add 100g of silica to 400g of anhydrous ethanol, stir at 500rpm for 30min, increase the speed to 9000rpm, and shear disperse for 35min to obtain a suspension. S2: Add 14g of silane coupling agent KH-550 hydrolysate to 100g of suspension, heat to 60℃, rotate at 400rpm, reflux for 5h, after the reaction is complete, cool to 25℃, filter, dry, pulverize and sieve to obtain modified nano silica.

[0030] Example 6: Preparation of a modified nano-silica S1: Add 100g of silica to 420g of anhydrous ethanol, stir at 600rpm for 20min, increase the speed to 10000rpm, and shear disperse for 30min to obtain a suspension. S2: Add 15g of silane coupling agent KH-550 hydrolysate to 100g of suspension, heat to 65℃, rotate at 300rpm, reflux for 6h, after the reaction is complete, cool to 20℃, filter, dry, pulverize and sieve to obtain modified nano silica.

[0031] Example 7: Preparation of a modified TPU-based prepolymer Under a nitrogen atmosphere, 100g of 4,4'-diphenylmethane diisocyanate was added to 454g of poly(1,4-butanediol adipate), the temperature was raised to 55°C, the rotation speed was 250rpm, 0.13g of dibutyltin dilaurate catalyst was added, the temperature was raised to 75°C, and the reaction was carried out for 3 hours. After the reaction was completed, the temperature was lowered to 20°C to obtain the modified TPU-based prepolymer.

[0032] Example 8: Preparation of a modified TPU-based prepolymer Under a nitrogen atmosphere, 100g of 4,4'-diphenylmethane diisocyanate was added to 454.5g of poly(1,4-butanediol adipate), the temperature was raised to 60℃, the rotation speed was 200rpm, 0.135g of dibutyltin dilaurate catalyst was added, the temperature was raised to 80℃, and the reaction was carried out for 2.5h. After the reaction was completed, the temperature was lowered to 25℃ to obtain the modified TPU-based prepolymer.

[0033] Example 9: Preparation of a modified TPU-based prepolymer Under a nitrogen atmosphere, 100g of 4,4'-diphenylmethane diisocyanate was added to 455g of poly(1,4-butanediol adipate), the temperature was raised to 65°C, the rotation speed was 150rpm, 0.14g of dibutyltin dilaurate catalyst was added, the temperature was raised to 85°C, and the reaction was carried out for 2 hours. After the reaction was completed, the temperature was lowered to 30°C to obtain the modified TPU-based prepolymer.

[0034] Example 10: A novel TPU film S1: Add 60g of Shore A 85A TPU particles, 50g of modified nitrile rubber, 3g of modified nano silica, 2g of hollow glass microspheres, 15g of 1,4-butanediol and 5g of modified TPU-based prepolymer to a high-speed mixer, heat to 180℃, rotate at 400rpm, mix for 3min, reduce pressure to -0.08 to -0.1MPa, react for 3min, the reaction is complete, cool to 20℃ to obtain modified TPU composite particles; S2: Add 100g of modified TPU composite particles to a single-screw casting machine, set the screen pressure to 7Kpa, heat to 100℃, dry for 3 hours, set the screw zone 1 temperature to 190℃, screw zone 2 temperature to 185℃, screw zone 3 temperature to 200℃, screw speed to 40rpm, front roller temperature to 35℃, middle roller temperature to 40℃, rear roller temperature to 30℃, cool and crystallize, and cool down to 8℃ to obtain a new type of TPU film.

[0035] Example 11: A novel TPU film S1: Add 70g of Shore A 85A TPU particles, 60g of modified nitrile rubber, 5g of modified nano silica, 2.5g of hollow glass microspheres, 20g of 1,4-butanediol and 8g of modified TPU-based prepolymer to a high-speed mixer, heat to 1900℃, rotate at 350rpm, mix for 4min, reduce pressure to -0.08 to -0.1MPa, react for 2.5min, the reaction is complete, cool to 25℃ to obtain modified TPU composite particles; S2: Add 100g of modified TPU composite particles to a single-screw casting machine, set the screen pressure to 10Kpa, heat to 90℃, dry for 3.5h, screw zone 1 185℃, screw zone 2 190℃, screw zone 3 195℃, screw speed 50rpm, front roller 30℃, middle roller 45℃, rear roller 25℃, cool and crystallize, and cool down to 10℃ to obtain a new type of TPU film.

[0036] Example 12: A novel TPU film S1: Add 80g of Shore A 85A TPU particles, 70g of modified nitrile rubber, 7g of modified nano silica, 3g of hollow glass microspheres, 25g of 1,4-butanediol and 10g of modified TPU-based prepolymer to a high-speed mixer, heat to 200℃, rotate at 300rpm, mix for 5min, reduce pressure to -0.08 to -0.1MPa, react for 2min, the reaction is complete, cool to 30℃ to obtain modified TPU composite particles; S2: Add 100g of modified TPU composite particles to a single-screw casting machine, set the pre-cast pressure to 12Kpa, heat to 80℃, dry for 4 hours, set the screw zone 1 temperature to 180℃, screw zone 2 temperature to 195℃, screw zone 3 temperature to 190℃, screw speed to 60rpm, front roller temperature to 25℃, middle roller temperature to 50℃, and rear roller temperature to 20℃, cool and crystallize, and cool down to 12℃ to obtain a new type of TPU film.

[0037] Comparative Example 1: Compared with Example 10, this comparative example did not add any modified TPU-based prepolymer during the preparation of the novel TPU film. All other steps and parameters were the same, and will not be repeated here. The novel TPU film was finally obtained.

[0038] Comparative Example 2: This comparative example differs from Example 10 only in that "modified nano silica" is replaced with "nano silica". All other steps and parameters are the same, and will not be repeated here. The final result is a novel TPU film.

[0039] Comparative Example 3: This comparative example differs from Example 10 only in that "modified nitrile rubber" is replaced with "nitrile rubber". All other steps and parameters are the same, and will not be repeated here. The final result is a novel TPU film.

[0040] Performance testing: Tensile strength and elongation at break According to the ASTM D412 test standard, a UTM-2100 universal tensile testing machine was used with a tensile speed of 500 mm / min.

[0041] Tear strength test According to the ASTM D624 test standard, a UTM-2100 universal tensile testing machine was used, with right-angled specimens.

[0042] Table 1 Test data of the examples and comparative examples Oil resistance test: According to the GB / T 1690-2010 testing standard, the test liquid is IRM 903 oil; 1. Take the TPU films from Examples 10-12 and Comparative Examples 1-3 respectively, cut them into 25mm×25mm square samples, weigh them, and record them as M1; 2. Place the sample in IRM903 oil, ensuring that the sample is completely submerged, and soak at 23±2℃ for 70 hours. After soaking, clean and let stand, weigh, and record M2. 3. Calculation formula: Melt Flow Index The XNR-400A melt flow indexer was used in accordance with the GB / T 3682.1-2018 test standard. 1. Take 5.0g of each of the modified TPU composite particles from Examples 10-12 and Comparative Examples 1-3, place them in a drying oven, heat to 90℃, dry for 4 hours, and then take out the samples. 2. Place the sample in the hot furnace cylinder, heat it to 190℃, and keep it at the temperature for 15-20 minutes. Add a standard weight of 5.000 kg to the top of the piston rod. The piston rod will start to move down. When it descends to the level of the lower ring mark with the top surface of the furnace cylinder opening, immediately use a scraper to cut off the strip of material extruded from the die. Cut the strip of material every 30 seconds and weigh it. 3. Formula for calculating melt mass flow rate (MFR): The Taber 5900-Taber abrasion tester was used in accordance with the ASTM D4060 test standard. 1. Take TPU films from Examples 10-12 and Comparative Examples 1-3 respectively, cut them into 100mm×100mm samples, drill a 6.5mm round hole in the center, place them at 23±2℃ and 50±5% relative humidity for 24h, weigh them again, and record them as M1. 2. Fix the sample in the abrasion tester, use the CS-17 model friction wheel, the load of the load arm is 500g, the rotation speed is 1000 revolutions, after the test is completed, clean it, place it at a temperature of 23±2℃ and a relative humidity of 50±5% for 1 hour, and then weigh it again, and record it as M2. 3. Formula for calculating mass loss value: .

[0043] Table 2 Test data for the examples and comparative examples Data Analysis: As can be seen from Tables 1 and 2, the novel TPU film prepared by this invention has higher mechanical strength, better oil resistance, suitable processing fluidity, and superior abrasion resistance. In contrast, Comparative Example 1, lacking the addition of modified TPU-based prepolymer, exhibited a comprehensive deterioration in mechanical properties and wear resistance. The core reason for this is that relying solely on the small-molecule chain extender BDO only achieves linear elongation of the TPU molecular chains, failing to construct an effective "bridging" structure at the TPU-nitrile interface. The lack of a prepolymer acting as a macromolecular chain extender resulted in extremely low efficiency of the in-situ grafting reaction between the TPU's -NCO groups and the unsaturated bonds of the nitrile, leading to poor phase compatibility and weak interfacial bonding. This macroscopic phase separation makes the material prone to interfacial debonding under stress, rapidly initiating failure and manifesting as a significant decrease in strength, toughness, and wear resistance. Simultaneously, the insufficient number of effective physical crosslinking points between molecular chains also led to an abnormally high melt flow index, indicating a deterioration in the material's creep resistance. In Comparative Example 2, the reinforcement and toughening effect failed to meet expectations because the modified nano-silica was replaced with nano-silica. The fundamental reason is that the unmodified nano-silica has a large number of silanol groups on its surface, and the intermolecular hydrogen bonding is extremely strong. This makes it very easy to agglomerate in the non-polar polymer matrix, forming micron-sized secondary aggregates. These aggregates not only fail to provide the reinforcement effect that should be provided at the nanoscale, but also become stress concentration points. Under stress, they become crack initiation points and accelerate material failure. Therefore, the improvement of the mechanical properties of the material is limited. Moreover, due to stress concentration, micro-tears and spalling are more likely to occur during the wear process, resulting in increased wear and tear. The wear resistance is actually worse than that of the example. Comparative Example 3, by replacing the modified nitrile rubber with nitrile rubber, resulted in the complete loss of its oil resistance. The underlying mechanism is that the oil resistance of nitrile rubber originates from the polar acrylonitrile groups on its molecular chain. The lower the acrylonitrile content, the weaker the polarity of the rubber molecules. According to the principle of "like dissolves like," its resistance to non-polar oils is worse. Oil molecules are more likely to swell and even dissolve the low-polarity rubber phase, causing the blend to expand rapidly, leading to severe loss of its dimensional stability and physical properties in oil. This indicates that simple blending cannot achieve oil resistance; NBR with a high acrylonitrile content must be used as the functional component. Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0044] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A novel TPU film, characterized in that, It is composed of the following components in parts by weight: 60-80 parts of TPU raw material particles with a Shore hardness of 85A, 50-70 parts of modified nitrile rubber, 3-7 parts of modified nano-silica, 2-3 parts of hollow glass microspheres, 15-25 parts of 1,4-butanediol, and 5-10 parts of modified TPU-based prepolymer. The modified nitrile rubber is a nitrile rubber with high acrylonitrile content; The modified nano-silica is nano-silica with surface modification by silane coupling agent KH-550; The modified TPU-based prepolymer is an isocyanate-terminated TPU-based prepolymer.

2. The novel TPU film according to claim 1, characterized in that, The preparation steps of the modified nitrile rubber are as follows: Butadiene, potassium disproportionated rosinate soap as emulsifier, acrylonitrile, and tert-dodecyl mercaptan are added to deionized water, heated to 20-30℃, rotated at 60-80 rpm, and emulsified for 50-70 minutes. The temperature is then raised to 35-45℃, potassium persulfate as initiator is added, and the reaction is carried out for 10-12 hours. Sodium dimethyl dithiocarbamate as terminator is added. Once the reaction is complete, impurities are removed, the mixture is washed, dehydrated, and dried to obtain modified nitrile rubber.

3. The novel TPU film according to claim 2, characterized in that, The mass ratio of butadiene, emulsifier, acrylonitrile, tert-dodecyl mercaptan, initiator and terminator is 1:0.04-0.06:0.65-0.67:0.0065-0.0067:0.004-0.006:0.0015-0.0017.

4. The novel TPU film according to claim 1, characterized in that, The preparation steps of the modified nano-silica are as follows: Step A1: Add silica to anhydrous ethanol, stir at 400-600 rpm for 20-40 min, increase the speed to 8000-10000 rpm, and shear disperse for 30-40 min to obtain a suspension; Step A2: Add the hydrolysate of silane coupling agent KH-550 to the suspension, heat to 55-65℃, rotate at 300-500 rpm, reflux for 4-6 hours. After the reaction is complete, cool to 20-30℃, filter and dry, pulverize and sieve to obtain modified nano-silica.

5. A novel TPU film according to claim 4, characterized in that, The mass ratio of silicon dioxide to anhydrous ethanol in step A1 is 1:3.8-4.

2.

6. A novel TPU film according to claim 4, characterized in that, The mass ratio of the hydrolysate to the suspension in step A2 is 0.12-0.15:

1.

7. A novel TPU film according to claim 1, characterized in that, The preparation steps of the modified TPU-based prepolymer are as follows: Under a nitrogen atmosphere, 4,4'-diphenylmethane diisocyanate was added to poly(1,4-butanediol adipate), the temperature was raised to 55-65°C, the rotation speed was 150-250 rpm, dibutyltin dilaurate was added as a catalyst, the temperature was raised to 75-85°C, and the reaction was carried out for 2-3 hours. After the reaction was completed, the temperature was lowered to 20-30°C to obtain the modified TPU-based prepolymer.

8. A novel TPU film according to claim 7, characterized in that, The mass ratio of 4,4'-diphenylmethane diisocyanate, poly(1,4-butanediol adipate) diol, and catalyst is 1:4.54-4.55:0.0013-0.0014.

9. A novel TPU film according to claim 1, characterized in that, The specific preparation steps are as follows: Step S1: Add TPU particles with a Shore hardness of 85A, modified nitrile rubber, modified nano silica, hollow glass microspheres, 1,4-butanediol and modified TPU-based prepolymer to a high-speed mixer, heat to 180-200℃, rotate at 300-400 rpm, mix for 3-5 minutes, reduce pressure to -0.08 to -0.1 MPa, react for 2-3 minutes, after the reaction is complete, cool to 20-30℃ to obtain modified TPU composite particles; Step S2: Add the modified TPU composite particles into a single-screw casting machine, set the pre-cast pressure to 7-12 kPa, heat to 80-100℃, dry for 3-4 hours, with screw zone 1 at 180-190℃, screw zone 2 at 185-195℃, screw zone 3 at 190-200℃, screw speed at 40-60 rpm, front roller at 25-35℃, middle roller at 40-50℃, and rear roller at 20-30℃, cool and crystallize, and lower the temperature to 8-12℃ to obtain a novel TPU film.

10. A novel TPU film according to claim 9, characterized in that, The hollow glass microspheres have a particle size of 10-50 μm.

Images