TPU (thermoplastic polyurethane) film as well as preparation method and application thereof

Abstract

The invention discloses a TPU (thermoplastic polyurethane) film as well as a preparation method and application thereof. The TPU film comprises a base cloth layer, a bonding layer and a functional layer, the bonding layer is prepared from the following components: a first TPU base material, polymethyl methacrylate, a compatilizer and an antioxidant; the functional layer comprises the following components: a second TPU base material, fluorocarbon betaine, silicone, an ultraviolet absorbent and a coupling agent. The TPU film disclosed by the invention can also realize better water resistance and pollution resistance on the premise of keeping better adhesive property and better aging resistance.

Description

Technical Field

[0001] This invention relates to a TPU film, its preparation method, and its applications. Background Technology

[0002] Thermoplastic polyurethane elastomer (TPU) possesses excellent mechanical strength, flexibility, abrasion resistance, and chemical resistance, and is widely used in automotive interiors, outdoor products, bags, and footwear. As the automotive industry upgrades towards lightweighting, intelligentization, and greening, automotive interior leather materials are gradually shifting from traditional PVC leather and solvent-based PU leather to environmentally friendly TPU synthetic leather. This places more stringent requirements on the weather resistance, abrasion resistance, stain resistance, and long-term dimensional stability of TPU synthetic leather.

[0003] Currently, automotive TPU synthetic leather still faces several technical bottlenecks in practical applications:

[0004] 1. Insufficient resistance to yellowing: Ordinary aromatic TPU is prone to molecular chain oxidative degradation under the combined action of ultraviolet light, high temperature and oxygen, generating chromophores that cause the material to yellow and darken. After long-term use, the appearance deteriorates significantly and the mechanical properties decline, making it difficult to meet the color stability requirements of automotive interiors under long-term light exposure.

[0005] 2. Shortcomings in wear resistance and stain resistance: Conventional TPU has a relatively high coefficient of friction and high surface energy, making it easy to get scratched and stained during daily contact, and the stains are difficult to wipe off; high-frequency use areas (such as seat side wings and door armrests) are prone to wear, fuzzing, and whitening, affecting the feel and service life.

[0006] 3. Interlayer bonding and process defects: Existing TPU synthetic leathers mostly use adhesives for bonding, which has problems such as low interlayer peel strength, poor heat aging resistance, and easy aging and failure of adhesive layers; at the same time, traditional processes are cumbersome and have low production efficiency, making it difficult to meet the needs of large-scale, high-quality automotive interior manufacturing.

[0007] Although the industry has improved individual properties through methods such as selecting aliphatic TPU, adding light stabilizers, antioxidants, or surface modification, it still lacks a technical solution that integrates and synergistically improves yellowing resistance, abrasion and stain resistance, and strong interlayer bonding, failing to simultaneously meet the comprehensive requirements of automotive interiors for appearance, environmental protection, feel, and durability. Therefore, developing a TPU synthetic leather with excellent yellowing resistance, high abrasion and stain resistance, and strong interlayer bonding, along with its efficient preparation process, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] The technical problem this invention aims to solve is to overcome the shortcomings of existing TPU films in simultaneously achieving excellent adhesion, aging resistance, and water and stain resistance, and to provide a TPU film, its preparation method, and its applications. The TPU film of this invention achieves excellent water and stain resistance while maintaining good adhesion and aging resistance.

[0009] The present invention solves the above-mentioned technical problems through the following technical solution:

[0010] This invention provides a TPU film comprising a base fabric layer, an adhesive layer, and a functional layer;

[0011] The adhesive layer comprises the following components: a first TPU base material, polymethyl methacrylate, a compatibilizer, and an antioxidant;

[0012] The functional layer comprises the following components: a second TPU base material, fluorobetaine, silicone, ultraviolet absorber, and coupling agent.

[0013] In this invention, the first TPU base material can be a conventional thermoplastic polyurethane material in the art, preferably a polyether-type TPU or a polyester-type TPU, such as a polyether-type TPU.

[0014] In this invention, the Shore hardness of the first TPU base material can be 60A-70A, for example 70A.

[0015] In a preferred embodiment, the grade of the first TPU base material is preferably BASF-manufactured model 1170.

[0016] In this invention, the weight percentage of the first TPU base material can be 74-90 parts, for example 74, 80 or 84 parts.

[0017] In this invention, the Shore hardness of the polymethyl methacrylate is preferably 50A-65A, for example 60A.

[0018] In this invention, the melt index of the polymethyl methacrylate can be 3-6 g / 10 min, for example 4 g / 10 min. The melt index is measured at 190°C and 2.16 kg.

[0019] In this invention, the weight-average molecular weight of the polymethyl methacrylate can be 30,000-50,000, for example, 35,000-45,000.

[0020] In a preferred embodiment, the polymethyl methacrylate has a Shore hardness of 60A, a melt index of 4 g / 10 min, and a weight-average molecular weight of 35,000-45,000.

[0021] In a more preferred embodiment, the polymethyl methacrylate is preferably of the grade SA-CW001 manufactured by Kuraray, Japan.

[0022] In this invention, the polymethyl methacrylate is preferably 10-20 parts by weight, for example 10, 12, 15, 17, 19 or 20 parts.

[0023] In this invention, the Shore hardness of the first TPU base material, the second TPU base material, and the polymethyl methacrylate is measured according to ASTM D2240.

[0024] In this invention, the compatibilizer can be of the conventional type in the art, preferably including maleic anhydride grafted polymers, such as polyurethane elastomer-maleic anhydride (TPU-g-MAH).

[0025] The grafting rate of the maleic anhydride grafted polymer can be greater than 0.6%, for example, 0.6%, 0.8% or 1.2%.

[0026] In this invention, the compatibilizer is preferably expressed in 1-8 parts by weight, for example, 3 or 6 parts.

[0027] In this invention, the antioxidant is preferably a composite antioxidant. The composite antioxidant may include a primary antioxidant and a secondary antioxidant.

[0028] The primary antioxidant is preferably a hindered phenolic compound. The hindered phenolic compound is preferably pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. The secondary antioxidant is preferably a phosphite compound. The phosphite compound is preferably tris[2,4-di-tert-butylphenyl]phosphite. When the antioxidant is a hindered phenolic compound and a phosphite compound, the mass ratio of the hindered phenolic compound to the phosphite compound is preferably (0.5-1.5):1, for example, 1:1.

[0029] In a preferred embodiment, the antioxidant is a composite antioxidant comprising pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and tris[2,4-di-tert-butylphenyl] phosphite in a mass ratio of 1:1.

[0030] In this invention, the antioxidant is preferably 0.1-0.5 parts by weight, for example 0.2 or 0.5 parts.

[0031] In this invention, the second TPU base material can be a conventional thermoplastic polyurethane material in the art, preferably a polyether-type TPU or a polyester-type TPU, such as a polyether-type TPU.

[0032] In this invention, the Shore hardness of the second TPU base material can be 85A-90A, for example 85A.

[0033] In a preferred embodiment, the grade of the second TPU base material is preferably BASF-manufactured model 1185.

[0034] In this invention, the weight percentage of the second TPU base material is preferably 90-95 parts, for example 91.5 parts.

[0035] In this invention, the fluorobetaine is preferably present in 1-5 parts by weight, for example, 1.5 or 3 parts.

[0036] In a preferred embodiment, the fluorobetaine is of the grade CF167M produced by Jinan Qifu New Materials.

[0037] In this invention, the particle size of the silicone is preferably 10-15 μm, for example 12 μm.

[0038] In this invention, the silicone is preferably expressed in 1-5 parts by weight, for example, 3 or 4 parts.

[0039] In a preferred embodiment, the silicone is of grade S201 produced by Chengdu Silike Technology Co., Ltd.

[0040] In this invention, the type of ultraviolet absorber can be selected according to conventional methods in the art, preferably including benzophenone-based ultraviolet absorbers and / or benzotriazole-based ultraviolet absorbers.

[0041] Among them, the benzophenone-based ultraviolet absorber is preferably a 2-hydroxybenzophenone-based ultraviolet absorber, such as BSF Chimassorb 81. The benzotriazole compound is preferably a benzotriazole compound containing hydroxyphenyl, such as 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (BASF Tinuvin 234).

[0042] When the ultraviolet absorber is preferably a benzophenone-based ultraviolet absorber or a benzotriazole-based ultraviolet absorber, the mass ratio of the benzophenone-based ultraviolet absorber to the benzotriazole-based ultraviolet absorber is (0.5-1.5):1, for example, 1:1.

[0043] In this invention, the coupling agent can be of a type conventional in the art, such as a titanate coupling agent.

[0044] In this invention, the coupling agent is preferably 1-5 parts by weight, for example 0.5 or 0.8 parts.

[0045] In this invention, color masterbatch is preferably also added to the functional layer. The color masterbatch refers to a masterbatch that can impart color to the TPU film, and different colors of color masterbatch can be selected according to actual needs, such as brown color masterbatch. The weight percentage of the color masterbatch is preferably 0.5-2 parts, for example 1.2 or 1.8 parts.

[0046] In a preferred embodiment 1, the adhesive layer comprises 74 parts of a first TPU base material, 20 parts of polymethyl methacrylate, 6 parts of compatibilizer, and 0.5 parts of antioxidant; the functional layer comprises 90 parts of a second TPU base material, 3 parts of fluorobetaine, 4 parts of silicone, 1 part of ultraviolet absorber, 0.8 parts of coupling agent, and 1.2 parts of color masterbatch.

[0047] In a preferred embodiment 2, the adhesive layer comprises 84 parts of a first TPU base material, 10 parts of polymethyl methacrylate, 6 parts of compatibilizer, and 0.5 parts of antioxidant; the functional layer comprises 90 parts of a second TPU base material, 3 parts of fluorobetaine, 4 parts of silicone, 1 part of ultraviolet absorber, 0.8 parts of coupling agent, and 1.2 parts of color masterbatch.

[0048] In a preferred embodiment 3, the adhesive layer comprises 74 parts of a first TPU base material, 20 parts of polymethyl methacrylate, 6 parts of compatibilizer, and 0.5 parts of antioxidant, and the functional layer comprises 91.5 parts of a second TPU base material, 1.5 parts of fluorobetaine, 4 parts of silicone, 1 part of ultraviolet absorber, 0.8 parts of coupling agent, and 1.2 parts of color masterbatch.

[0049] In this invention, the thickness of the adhesive layer can be 0.15 mm.

[0050] In this invention, the thickness of the functional layer can be 0.05 mm.

[0051] In this invention, the thickness ratio of the adhesive layer to the functional layer can be (1-5):1, for example 2:1, 3:1 or 4:1.

[0052] In a preferred embodiment, the thickness of the adhesive layer is 0.15 mm; the thickness of the functional layer is 0.05 mm.

[0053] In this invention, the base fabric layer component preferably includes polyethylene terephthalate (PET).

[0054] In this invention, the TPU film preferably comprises a base fabric layer, an adhesive layer, and a functional layer arranged sequentially from bottom to top.

[0055] In this invention, the TPU film preferably does not include an adhesive. The adhesive is preferably a polyurethane-based adhesive.

[0056] In this invention, the TPU film is preferably TPU leather.

[0057] In this invention, the inventors discovered during the research and development process that the combination of silicone and fluorobetaine in the functional layer has a significant synergistic effect in reducing surface energy. After the combination, adding a small amount of silicone and fluorobetaine can achieve the effects of superhydrophobicity, low surface energy, and high antifouling. If fluorobetaine is used alone, even if the amount of fluorobetaine is doubled, it is difficult to reduce the surface energy of the resulting TPU film to below 25. If silicone is used alone, it is also difficult to reduce the surface energy of the resulting TPU film.

[0058] This invention provides a method for preparing a TPU film, which includes the following steps:

[0059] The adhesive layer mixture and the functional layer mixture are melt-blended separately, and then co-extruded and cast into films using a multi-layer co-extrusion die to obtain the adhesive layer and the functional layer; at the same time, the adhesive layer is combined with the base fabric layer to obtain the TPU film;

[0060] The adhesive layer mixture comprises: a first TPU base material, polymethyl methacrylate, a compatibilizer, and an antioxidant; the functional layer mixture comprises a second TPU base material, fluorobetaine, silicone, an ultraviolet absorber, and a coupling agent.

[0061] In this invention, the adhesive layer mixture is obtained by mixing the raw materials of the adhesive layer. The mixing is preferably carried out in a high-speed mixer. The mixing speed is 1000-1200 rpm, for example, 1100 rpm.

[0062] In this invention, the equipment used for melt blending can be conventional in the art, such as a multi-layer co-extrusion twin-screw extruder.

[0063] The main engine speed of the multi-layer co-extrusion twin-screw extruder is preferably 30-70 rpm, for example, 50 rpm.

[0064] In this invention, the processing temperature for melt blending is preferably 100-300℃, for example, 200℃.

[0065] In this invention, preferably, the adhesive layer mixture flows through the lower layer of the multilayer co-extrusion die, and the functional layer mixture flows through the upper layer of the co-extrusion die.

[0066] In this invention, preferably, the lower layer of the multi-layer co-extrusion die is provided with a base fabric layer.

[0067] In this invention, the functional layer preferably also undergoes texture transfer. The texture transfer is preferably performed using a cooled texture roller. The transfer temperature is preferably 20-40°C, for example, 30°C. The transfer pressure is preferably 0.2-0.6 MPa, for example, 0.4 MPa.

[0068] The present invention also provides an application of the TPU film as described above in the leather industry.

[0069] In this invention, the leather sector preferably includes one or more of automotive interiors, outdoor products, and bags. The automotive interiors are preferably automotive seats and / or door panels. The outdoor products preferably include outdoor tents.

[0070] The positive and progressive effects of this invention are as follows:

[0071] (1) The TPU film of the present invention can achieve better water and stain resistance (scratch resistance grade > 4 and stain resistance grade ≥ 5) while maintaining better adhesion performance (interlayer peel strength ≥ 15N / 25mm) and better aging resistance (photoaging energy level can be 4-5).

[0072] (2) The TPU film preparation method of the present invention has high production efficiency (can be increased by more than 40%), easy control of process parameters, and is more environmentally friendly (no adhesive is required). It can achieve large-scale production, and the color and texture of the TPU film can be adjusted according to the needs to adapt to different application scenarios. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of the structure of the composite layered material of the present invention.

[0074] Explanation of reference numerals in the attached figures:

[0075] 1-Base fabric layer; 2-Adhesive layer; 3-Functional layer; Detailed Implementation

[0076] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0077] The types and manufacturers of the raw materials used in the following examples and comparative examples are shown in the table below:

[0078]

[0079] Examples 1-3, Comparative Examples 1-5

[0080] The compositions of the TPU films in Examples 1-3 and Comparative Examples 1-5 are shown in Table 1 below.

[0081] The preparation methods of the TPU films in Examples 1-3 and Comparative Examples 1-5 include the following steps:

[0082] (1) Each component of the adhesive layer and each component of the functional layer in Table 1 are put into a high-speed mixer and stirred evenly at a speed of 1100 rpm to obtain adhesive layer mixture and functional layer mixture respectively.

[0083] (2) The binder mixture and the functional layer mixture are fed into a multi-layer co-extrusion twin-screw extruder respectively; the binder mixture is set to flow through the lower layer of the multi-layer co-extrusion die and the functional layer mixture is set to flow through the upper layer of the co-extrusion die; the lower layer of the multi-layer co-extrusion die is provided with a PET fiber base fabric layer. Production process parameters: the main speed of the multi-layer co-extrusion twin-screw extruder is 50 rpm, and the overall extrusion processing temperature is set to 200℃.

[0084] Two materials are co-extruded and cast into a film using a multi-layer co-extrusion die, and then laminated with a PET fiber base fabric layer to form a TPU multi-layer co-extruded substrate. At the same time, a cooling texture roller is used to cool and emboss the surface of the functional layer to transfer the texture. The roller temperature is controlled at 30°C and the pressing pressure is 0.4MPa, so that the surface layer can be accurately shaped to form the required texture.

[0085] The thickness of the adhesive layer of the obtained TPU film is 0.15 mm, the thickness of the functional layer is 0.05 mm, and the ratio of the thickness of the adhesive layer to the thickness of the functional layer is 3:1.

[0086] Table 1

[0087]

[0088]

[0089] Effect Example

[0090] Peel strength, light aging level, color difference (ΔENBS), surface energy, static friction and dynamic friction of the TPU films prepared in Examples 1-3 and Comparative Examples 1-5 were tested respectively.

[0091] The peel strength test method is as follows: First, the samples (TPU films prepared in Examples 1-3 and Comparative Examples 1-5) are kept at a constant temperature and balanced for more than 2 hours in an environment of 23±2℃ and 50±5% RH. The samples are then cut to a specified width (usually 25mm). When using a peel testing machine, the peel test sample ends are clamped in the upper fixture. The equipment is calibrated and zeroed, and the standard peel angle (180° / 90°) and test speed of 300mm / min are set. The machine is started and the effective stroke peel is completed at a uniform speed. The tensile force data in the stable range is collected, and the peel strength is calculated according to the sample width. Multiple sets of samples are tested in parallel, and outliers are eliminated.

[0092] The test method or standard for light aging grade and color difference (△ENBS) is ASTM G154, and then the △E value is obtained by measuring with a colorimeter.

[0093] Surface energy testing method or standard: Based on the Owens-Wendt-Rabel-Kaelble (WORK) two-liquid method calculation model, the solid surface energy is obtained by fitting the contact angle data of ultrapure water (polar liquid) and diiodomethane (non-polar liquid);

[0094] Test standards for static and dynamic friction: GB / T 10006-2021.

[0095] The test results are shown in Table 2.

[0096] Table 2

[0097]

[0098] As shown in Table 2, the TPU films of Examples 1-3 of this application can have good adhesion, yellowing resistance and water and stain resistance.

[0099] In Comparative Example 1, without the addition of an adhesive layer, the resulting TPU film exhibited poor adhesion (poor peel strength) and also poor resistance to yellowing (ΔENBS was even 1.51).

[0100] In Comparative Example 2, without the addition of fluorobetaine, the resulting TPU film exhibited poor water and stain resistance (high surface energy) and high friction.

[0101] In Comparative Example 3, without the addition of silicone, the resulting TPU film had poor water and stain resistance (high surface energy) and high friction.

[0102] In Comparative Example 4, no UV absorber was added, and the resulting TPU film had poor resistance to yellowing.

[0103] In Comparative Example 5, when fluorobetaine was replaced with fluorinated modified acrylate resin, the resulting TPU film had poor water and stain resistance (high surface energy).

[0104] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A TPU film, characterized in that, It includes a base fabric layer, an adhesive layer, and a functional layer; The adhesive layer comprises the following components: a first TPU base material, polymethyl methacrylate, a compatibilizer, and an antioxidant; The functional layer comprises the following components: a second TPU base material, fluorobetaine, silicone, ultraviolet absorber, and coupling agent.

2. The TPU film as described in claim 1, characterized in that, The TPU film satisfies one or more of the following conditions: (1) The first TPU base material is a polyether-type TPU or a polyester-type TPU, such as a polyether-type TPU; (2) The Shore hardness of the first TPU base material is 60A-70A, for example 70A; (3) The Shore hardness of the polymethyl methacrylate is 50A-65A, for example 60A; (4) The melt index of the polymethyl methacrylate is 3-6 g / 10 min, for example 4 g / 10 min; (5) The weight-average molecular weight of the polymethyl methacrylate is 30,000-50,000, for example 35,000-45,000; (6) The compatibilizers include maleic anhydride grafted polymers, such as polyurethane elastomer-maleic anhydride. The grafting rate of the maleic anhydride-grafted polymer is preferably greater than 0.6%, for example, 0.6%, 0.8%, or 1.0%. (7) The antioxidant is preferably a compound antioxidant; the compound antioxidant preferably includes a primary antioxidant and a secondary antioxidant; The primary antioxidant is preferably a hindered phenolic compound; the hindered phenolic compound is preferably pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]; the secondary antioxidant is preferably a phosphite compound; the phosphite compound is preferably tris[2,4-di-tert-butylphenyl]phosphite; when the antioxidant is a hindered phenolic compound and a phosphite compound, the mass ratio of the hindered phenolic compound to the phosphite compound is preferably (0.5-1.5):1, for example 1:

1.

3. The TPU film as described in claim 1, characterized in that, The TPU film satisfies one or more of the following conditions: (1) The first TPU base material is 74-90 parts by weight, for example 74, 80 or 84 parts; (2) The polymethyl methacrylate is 10-20 parts by weight, for example 10, 12, 15, 17, 19 or 20 parts; (3) The compatibilizer is 1-8 parts by weight, for example 3 or 6 parts; (4) The antioxidant is 0.1-0.5 parts by weight, for example 0.2 or 0.5 parts.

4. The TPU film as described in claim 1, characterized in that, The TPU film satisfies one or more of the following conditions: (1) The second TPU base material is polyether-type TPU or polyester-type TPU, such as polyether-type TPU; (2) The Shore hardness of the second TPU base material is 85A-90A, for example 85A; (3) The particle size of the silicone is 10-15 μm, for example 12 μm; (4) The types of ultraviolet absorbers include benzophenone ultraviolet absorbers and / or benzotriazole ultraviolet absorbers; Among them, the benzophenone-based ultraviolet absorber is preferably a 2-hydroxybenzophenone-based ultraviolet absorber, such as BSFChimassorb 81; the benzotriazole compound is preferably a benzotriazole compound containing hydroxyphenyl, such as 2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol (BASF Tinuvin 234). When the ultraviolet absorber is preferably a benzophenone-based ultraviolet absorber and a benzotriazole-based ultraviolet absorber, the mass ratio of the benzophenone-based ultraviolet absorber to the benzotriazole-based ultraviolet absorber is (0.5-1.5):1, for example, 1:1; (5) The coupling agent is a titanate coupling agent; (6) Color masterbatch is also added to the functional layer; The color masterbatch is preferably 0.5-2 parts by weight, for example 1.2 or 1.8 parts.

5. The TPU film as described in claim 1, characterized in that, The TPU film satisfies one or more of the following conditions: (1) The weight of the second TPU base material is 90-95 parts, for example 91.5 parts; (2) The fluorobetaine is in the form of 1-5 parts by weight, for example 1.5 or 3 parts; (3) The silicone is in parts by weight of 1-5 parts, for example 3 or 4 parts; (4) The coupling agent is 1-5 parts by weight, for example 0.5 or 0.8 parts.

6. The TPU film as described in claim 1, characterized in that, The TPU film satisfies one or more of the following conditions: (1) The thickness ratio of the adhesive layer to the functional layer is (1-5):1, for example 2:1, 3:1 or 4:1; (2) The components of the base fabric layer include polyethylene terephthalate; (3) The TPU film comprises a base fabric layer, an adhesive layer and a functional layer arranged sequentially from bottom to top; (4) The TPU film does not include adhesive; the type of adhesive is preferably a polyurethane adhesive.

7. A method for preparing a TPU film, characterized in that, It includes the following steps: The adhesive layer mixture and the functional layer mixture are melt-blended separately, and then co-extruded and cast into films using a multi-layer co-extrusion die to obtain the adhesive layer and the functional layer; at the same time, the adhesive layer is combined with the base fabric layer to obtain the TPU film; The adhesive layer mixture comprises: a first TPU base material, polymethyl methacrylate, a compatibilizer, and an antioxidant; the functional layer mixture comprises a second TPU base material, fluorobetaine, silicone, an ultraviolet absorber, and a coupling agent.

8. The method for preparing the TPU film as described in claim 7, characterized in that, The method for preparing the TPU film satisfies one or more of the following conditions: (1) The adhesive layer mixture is obtained by mixing the raw materials of the adhesive layer; The mixing is preferably carried out in a high-speed mixer; the mixing speed is 1000-1200 rpm, for example 1100 rpm; (2) The equipment for melt blending is a multi-layer co-extrusion twin-screw extruder; The main engine speed of the multi-layer co-extrusion twin-screw extruder is preferably 30-70 rpm, for example 50 rpm; (3) The processing temperature of the melt blend is 100-300℃, for example 200℃.

9. The method for preparing the TPU film as described in claim 7, characterized in that, The method for preparing the TPU film satisfies one or more of the following conditions: (1) The adhesive layer mixture flows through the lower layer of the multilayer co-extrusion die, and the functional layer mixture flows through the upper layer of the co-extrusion die; (2) The lower layer of the multi-layer co-extrusion die is provided with a base fabric layer; (3) The functional layer also performs texture transfer; the texture transfer is preferably performed by cooling texture roller; the transfer temperature is preferably 20-40℃, for example 30℃; the transfer pressure is preferably 0.2-0.6MPa, for example 0.4MPa.

10. An application of a TPU film as described in any one of claims 1-6 in the leather industry.

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