Thermoplastic polyurethane, thermoplastic polyurethane film and preparation method and application thereof

Abstract

The present application relates to the technical field of polyurethane film, in particular to thermoplastic polyurethane, thermoplastic polyurethane film and its preparation method and application. The thermoplastic polyurethane is mainly made of the following components by weight fraction: polycarbonate polyol 40-60 parts, polyisocyanate 20-30 parts, chain extender 2-6 parts, reinforcing filler 0.05-0.1 parts and catalyst 0.01-0.03 parts. The soft segment obtained by the reaction of polycarbonate polyol and polyisocyanate has ultra-low resilience, the thermoplastic polyurethane has low shrinkage, and can avoid the separation of traditional polyurethane film due to shrinkage, so the thermoplastic polyurethane can be applied to large curved surface and small curved surface parts of different blades, expanding its application; at the same time, the hard segment obtained by the reaction of polyisocyanate and chain extender has high sand erosion resistance, which can ensure that the protected object is not damaged, and can be applied to the field of blade protection film with high speed operation, further expanding its application range.

Description

Technical Field

[0001] This invention relates to the field of polyurethane membrane technology, and more specifically, to thermoplastic polyurethane, thermoplastic polyurethane membranes, their preparation methods and applications. Background Technology

[0002] Polyurethane (PU), short for polyurethane, is a high-molecular-weight material with excellent mechanical properties and extremely high plasticity, formed by the condensation reaction of polyols and polyisocyanates. It is widely used in many fields, including: Packaging materials: Due to its good transparency and flexibility, polyurethane is often used in food and industrial packaging; Electronic product protection: In electronic products, polyurethane is commonly used for screen protectors and casing materials; Sports and outdoor equipment: For example, polyurethane is often used as a waterproof material in outdoor backpacks, tents, raincoats, etc.; Automotive industry: Polyurethane is used for the protection of interior and exterior parts in automobile manufacturing; Home furnishings: Polyurethane is used in curtains, bedspreads, tablecloths, and other products.

[0003] However, polyurethane produced by existing technologies has a high shrinkage rate and high resilience, which easily leads to detachment from the matrix material after shrinkage, making it unsuitable for use on curved parts of blades and limiting its applications. Furthermore, polyurethane produced by existing technologies has poor sand erosion resistance, posing a significant risk when applied to the field of protective films for high-speed blades.

[0004] Furthermore, to improve the strength of the polyurethane film, existing technologies employ interbonded polyurethane softening and hardening layers. However, this method, by bonding multiple layers together, carries the risk of poor interlayer bonding and easy delamination.

[0005] In addition, to improve the mechanical properties of polyurethane films, such as tensile strength and elongation at break, existing technologies use thermoplastic polyurethane, epoxy resin, plasticizers, fillers, and corrosion inhibitors to prepare a semi-finished product. During use, the semi-finished product is heated and melted before being sprayed onto the metal surface to form a protective film. However, this method suffers from problems such as poor spray uniformity, large thickness and high hardness of the resulting polyurethane film, and high construction difficulty, making it unsuitable for applications involving large curved surfaces such as propeller tips and radomes.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide a thermoplastic polyurethane. The soft segment obtained by reacting polycarbonate polyol with polyisocyanate exhibits ultra-low resilience. The thermoplastic polyurethane has a low shrinkage rate, which can avoid the detachment of traditional polyurethane films due to shrinkage. Therefore, this thermoplastic polyurethane can be applied to the large and small curved surfaces of different blades, expanding its applications. At the same time, the hard segment obtained by reacting polyisocyanate with chain extender has excellent sand erosion resistance, which can ensure that the protected object is not damaged. It can be applied to the field of high-speed blade protective films, expanding its application range.

[0008] The second objective of this invention is to provide a method for preparing thermoplastic polyurethane, which is simple, has a short process, and is easy to mass-produce.

[0009] A third objective of this invention is to provide a thermoplastic polyurethane film that combines ultra-low resilience with high sand erosion resistance, thereby facilitating the further promotion and application of thermoplastic polyurethane films. This solves the problem that existing thermoplastic polyurethane films suffer from high resilience and poor sand erosion resistance, which limits their application.

[0010] The fourth objective of this invention is to provide a method for preparing a thermoplastic polyurethane film. This method can obtain an integrally formed thermoplastic polyurethane film, which, while ensuring high tensile strength, solves the problems of poor interlayer bonding and easy delamination that exist in multilayer polyurethane films bonded by adhesive bonding. Furthermore, this method is simple to operate, and the thermoplastic polyurethane film prepared by this method has a low thickness, good uniformity, and high elongation at break. It solves the problems of poor spraying uniformity, high film thickness, high film hardness, and high construction difficulty that exist in the prior art of melting polyurethane semi-finished products and spraying them onto metal surfaces. It can be applied to large curved surface structural components such as propeller tips and radomes.

[0011] The fifth objective of this invention is to provide the application of thermoplastic polyurethane or thermoplastic polyurethane film in aircraft propeller blades, aircraft radomes, wind turbine blades, and front and rear bumpers of automobiles.

[0012] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0013] The present invention first provides a thermoplastic polyurethane, which is mainly composed of the following components in parts by weight: 40-60 parts of polycarbonate polyol, 20-30 parts of polyisocyanate, 2-6 parts of chain extender, 0.05-0.1 parts of reinforcing filler, and 0.01-0.03 parts of catalyst.

[0014] Furthermore, the molar mass of the polycarbonate polyol is 1000–3000 g / mol.

[0015] Furthermore, the polycarbonate polyol includes at least one of polytetramethylene carbonate diol, polyhexamethylene carbonate diol, and polycarbonate diol.

[0016] Furthermore, the median particle size of the reinforcing filler is 100–1000 μm.

[0017] Furthermore, the polyisocyanate includes diphenylmethane diisocyanate.

[0018] Furthermore, the chain extender includes at least one of ethylene glycol, 1,4-butanediol, hydroquinone, glycerol, trimethylolpropane, and sorbitol.

[0019] Furthermore, the reinforcing filler includes at least one of silica, mica powder, quartz sand, corundum, and corundum.

[0020] Furthermore, the catalyst comprises at least one of dibutyltin dilaurate, triethylenediamine, and N-dimethylethanolamine.

[0021] Furthermore, the components also include, by weight, 0.05 to 0.15 parts of antioxidant, 0.2 to 0.3 parts of ultraviolet absorber, and 0.1 to 0.2 parts of light stabilizer.

[0022] Furthermore, the antioxidant includes at least one selected from pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl)phosphite, n-octadecanoate, and N,N-bis-hexanediamine.

[0023] Furthermore, the ultraviolet absorber includes at least one of Euwint UV absorber UV1, benzotriazole UV-921, and ultraviolet absorber UV-1300.

[0024] Furthermore, the light stabilizer includes at least one of light stabilizer 770, nano-sized titanium dioxide, and hindered amine light stabilizers.

[0025] The present invention further provides a method for preparing the above-mentioned thermoplastic polyurethane, comprising the following steps: mixing the raw materials and carrying out a polycondensation reaction to obtain the thermoplastic polyurethane.

[0026] Further, the method of mixing the raw materials and carrying out the polycondensation reaction specifically includes: mixing polycarbonate polyol and chain extender and performing vacuum dehydration, wherein the vacuum dehydration temperature is 100-120°C, the vacuum dehydration time is 1-4 hours, and the vacuum degree of the vacuum dehydration is 665-1330 Pa; adding reinforcing filler, polyisocyanate and catalyst and stirring evenly; carrying out the reaction under vacuum conditions; after the reaction is completed, pouring the resulting mixture into a mold for curing, wherein the reaction temperature is 90-120°C, the reaction time is 30-60 minutes, the curing temperature is 100-120°C, and the curing time is 2-4 hours; and obtaining the polyurethane after cooling.

[0027] Further, the method of mixing the raw materials and carrying out the polycondensation reaction specifically includes: mixing polycarbonate polyol and chain extender and performing vacuum dehydration, wherein the vacuum dehydration temperature is 100-120°C, the vacuum dehydration time is 1-4 hours, and the vacuum degree of the vacuum dehydration is 665-1330 Pa; adding antioxidant, ultraviolet absorber, light stabilizer, reinforcing filler, polyisocyanate and catalyst, and stirring evenly; carrying out the reaction under vacuum conditions, and after the reaction is completed, pouring the resulting mixture into a mold for curing, wherein the reaction temperature is 90-120°C, the reaction time is 30-60 minutes, the curing temperature is 100-120°C, and the curing time is 2-4 hours; and obtaining the polyurethane after cooling.

[0028] The present invention also provides a thermoplastic polyurethane film, which is prepared from the above-described thermoplastic polyurethane, or prepared from the thermoplastic polyurethane obtained by the above-described method for preparing thermoplastic polyurethane.

[0029] Furthermore, the thickness of the thermoplastic polyurethane film is 0.3 to 0.5 mm.

[0030] The present invention also provides a method for preparing the above-mentioned thermoplastic polyurethane film, comprising the following steps: crushing the thermoplastic polyurethane and granulating it to obtain polyurethane particles; casting the polyurethane particles to obtain the thermoplastic polyurethane film.

[0031] Furthermore, the granulation temperature is 180–210°C.

[0032] Furthermore, after granulation and before casting, a vacuum drying step is included, wherein the vacuum drying temperature is 60–90°C and the vacuum drying time is 20–24 hours.

[0033] The present invention further provides the application of the above-mentioned thermoplastic polyurethane, or the thermoplastic polyurethane prepared by the above-mentioned method, or the thermoplastic polyurethane film, or the thermoplastic polyurethane film prepared by the above-mentioned method, in aircraft propeller blades, aircraft radomes, wind turbine blades, and front and rear bumpers of automobiles.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] (1) The thermoplastic polyurethane provided by the present invention has a soft segment with ultra-low resilience obtained by reacting polycarbonate polyol with polyisocyanate. The thermoplastic polyurethane has a low shrinkage rate, which can avoid the detachment of traditional polyurethane film due to shrinkage. Therefore, the thermoplastic polyurethane can be applied to the large and small curved surfaces of different blades, thus expanding its application. At the same time, the hard segment obtained by reacting polyisocyanate with chain extender has excellent sand erosion resistance, which can ensure that the protected object is not damaged. It can be applied to the field of high-speed blade protective film, thus expanding its application range.

[0036] (2) The thermoplastic polyurethane provided by the present invention can further reduce resilience by controlling the molar mass of polycarbonate polyol within a specific range.

[0037] (3) The thermoplastic polyurethane provided by the present invention can be uniformly dispersed in polyurethane by controlling the median particle size of the reinforcing filler, thereby improving the erosion resistance and toughness of the thermoplastic polyurethane film.

[0038] (4) The method for preparing thermoplastic polyurethane provided by the present invention is simple to operate, has a short process, and is easy to achieve mass production.

[0039] (5) The thermoplastic polyurethane film provided by this invention combines ultra-low resilience and high sand erosion resistance, which is conducive to the further promotion and use of thermoplastic polyurethane films. It solves the problem that the thermoplastic polyurethane film produced by the prior art has high resilience and poor sand erosion resistance, which limits its application.

[0040] (6) The method for preparing thermoplastic polyurethane film provided by the present invention can obtain an integrally formed thermoplastic polyurethane film. While ensuring high tensile strength, it solves the problems of poor interlayer bonding force and easy delamination in multilayer polyurethane films through adhesive bonding. Moreover, the method is simple to operate. The thermoplastic polyurethane film prepared by the method is thinner, more uniform, and has a higher elongation at break. It solves the problems of poor spraying uniformity, high film thickness, high film hardness, and high construction difficulty in the prior art of melting polyurethane semi-finished products and spraying them onto the metal surface. It can be applied to large curved surface structural parts such as propeller tips and radomes.

[0041] (7) The thermoplastic polyurethane and thermoplastic polyurethane film provided by the present invention can be applied to aircraft propellers, aircraft radomes, wind turbine blades and front and rear bumpers of automobiles, with a wider range of applications. Attached Figure Description

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 This is a schematic flowchart illustrating the preparation method of the thermoplastic polyurethane film provided by the present invention. Detailed Implementation

[0044] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0045] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0046] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0047] The present invention provides a thermoplastic polyurethane, which is mainly composed of the following components in parts by weight: 40-60 parts of polycarbonate polyol, 20-30 parts of polyisocyanate, 2-6 parts of chain extender, 0.05-0.1 parts of reinforcing filler, and 0.01-0.03 parts of catalyst.

[0048] The polycarbonate polyols, by weight, include but are not limited to point values ​​or ranges between any two of 40, 43, 45, 48, 50, 52, 55, 58, and 60 parts. The polyisocyanates, by weight, include but are not limited to point values ​​or ranges between any two of 20, 22, 23, 25, 26, 28, and 30 parts. The chain extenders, by weight, include but are not limited to point values ​​or ranges between any two of 2, 3, 4, 5, and 6 parts. The reinforcing fillers, by weight, include but are not limited to point values ​​or ranges between any two of 0.05, 0.06, 0.07, 0.08, 0.09, and 0.1 parts. The catalysts, by weight, include but are not limited to point values ​​or ranges between any two of 0.01, 0.02, and 0.03 parts.

[0049] The thermoplastic polyurethane provided by this invention combines ultra-low resilience and high sand erosion resistance. The soft segment obtained by reacting polycarbonate polyol with polyisocyanate exhibits ultra-low resilience, and the low shrinkage rate of the thermoplastic polyurethane avoids the detachment caused by shrinkage in traditional polyurethane films. Therefore, this thermoplastic polyurethane can be applied to both large and small curved surfaces of different blades, expanding its applications. Simultaneously, the hard segment obtained by reacting polyisocyanate with a chain extender possesses excellent sand erosion resistance, ensuring that the protected object is not damaged. This allows it to be applied to the field of high-speed blade protective films, further expanding its application range.

[0050] Specifically, polycarbonate polyols contain carbonate bonds (-O-CO-O-) in their backbone, exhibiting both high polarity and molecular chain rigidity. The polarity of the carbonate bond is stronger than that of the ether bond (-O-) in polyethers, but weaker than that of the ester bond (-COO-) in polyesters. This structure provides moderate intermolecular hydrogen bonding while reducing excessive crystallization caused by high polarity, thereby reducing volume shrinkage during curing. The carbonate bonds form a stable hydrogen bond network with the urethane groups in the hard segments of polyurethane, enhancing the compatibility between soft and hard segments, reducing microphase separation, and thus reducing volume changes caused by phase transitions. The hydrolysis resistance and oxidation resistance of the carbonate bonds are superior to those of polyesters and polyethers, reducing molecular chain breakage caused by thermal degradation during high-temperature processing or curing, thereby maintaining the stability of the crosslinked structure. By balancing polarity and flexibility, enhancing the hydrogen bond network, and optimizing the crosslinked structure, polycarbonate polyols significantly reduce the shrinkage rate of polyurethanes.

[0051] Meanwhile, the present invention uses polycarbonate polyols in combination with a specific ratio of polyisocyanates, chain extenders, reinforcing fillers and catalysts, which can also improve tensile strength, elongation at break and tensile strength in air heat aging tests.

[0052] Furthermore, the main chain of polycarbonate-type polyurethane made from polycarbonate polyols contains a large number of urethane groups (-NHCOO-) and carbonate groups (-OCOO-). These polar groups can form strong hydrogen bonds with the polar functional groups in acrylate pressure-sensitive adhesives. Therefore, this thermoplastic polyurethane has good adhesion to the backing adhesive, eliminating the need for corona treatment and avoiding the problem of brittleness after corona treatment.

[0053] In some specific embodiments, the molar mass of the polycarbonate polyol is 1000–3000 g / mol, including but not limited to values ​​of any one of 1000 g / mol, 1200 g / mol, 1500 g / mol, 1800 g / mol, 2000 g / mol, 2300 g / mol, 2500 g / mol, 2700 g / mol, and 3000 g / mol, or a range between any two. By controlling the molar mass of the polycarbonate polyol within the above range, this invention can further reduce shrinkage and improve tensile strength, elongation at break, tensile strength in air heat aging tests, and sand erosion resistance. Specifically, a molar mass of the polycarbonate polyol below 1000 g / mol will reduce tensile strength, tear strength, and abrasion resistance because high molecular weight polyols can form a stronger cross-linking network, thereby improving the load-bearing capacity of the polyurethane. However, if the molar mass of polycarbonate polyol exceeds 3000 g / mol, the high molecular weight of the polyol will lead to increased viscosity, which will reduce the fluidity during processing and make molding more difficult.

[0054] In some specific embodiments, the polycarbonate polyol includes at least one of polytetramethylene carbonate diol, polyhexamethylene carbonate diol, and polycarbonate diol. This is beneficial for reducing the shrinkage rate.

[0055] In some specific embodiments, the median particle size of the reinforcing filler is 100–1000 μm, including but not limited to a single value or a range between any two of 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, and 1000 μm. Controlling the particle size of the reinforcing filler within this range allows for uniform dispersion within the polyurethane particles. If the particle size of the reinforcing filler is too small, agglomeration is likely to occur, resulting in poor erosion resistance in localized areas of the thermoplastic polyurethane film. If the particle size of the reinforcing filler is too large, the dispersion performance will decrease, and the reinforcing filler will disrupt the cohesive forces between polyurethane molecules, leading to increased brittleness of the thermoplastic polyurethane film.

[0056] In some specific embodiments, the polyisocyanate includes diphenylmethane diisocyanate.

[0057] In some specific embodiments, the chain extender includes at least one of ethylene glycol, 1,4-butanediol, hydroquinone, glycerol, trimethylolpropane, and sorbitol.

[0058] In some specific embodiments, the reinforcing filler includes at least one of micron-sized silica, micron-sized mica powder, micron-sized quartz sand, micron-sized corundum, and micron-sized corundum.

[0059] In some specific embodiments, the catalyst includes at least one of dibutyltin dilaurate, triethylenediamine, and N-dimethylethanolamine.

[0060] Using the above-mentioned types of polyisocyanates, chain extenders, reinforcing fillers, and catalysts is beneficial to improving the overall performance of thermoplastic polyurethane films.

[0061] In some specific embodiments, the thermoplastic polyurethane composition further includes, by weight, 0.05 to 0.15 parts of antioxidant, 0.2 to 0.3 parts of ultraviolet absorber, and 0.1 to 0.2 parts of light stabilizer.

[0062] That is, thermoplastic polyurethane is made of the following components in parts by weight: 40-60 parts of polycarbonate polyol, 20-30 parts of polyisocyanate, 2-6 parts of chain extender, 0.05-0.1 parts of reinforcing filler, 0.01-0.03 parts of catalyst, 0.05-0.15 parts of antioxidant, 0.2-0.3 parts of ultraviolet absorber and 0.1-0.2 parts of light stabilizer.

[0063] The antioxidants, by weight, include, but are not limited to, point values ​​or ranges between any two of the following: 0.05 parts, 0.06 parts, 0.08 parts, 0.1 parts, 0.12 parts, 0.13 parts, and 0.15 parts. The ultraviolet absorbers, by weight, include, but are not limited to, point values ​​or ranges between any two of the following: 0.2 parts, 0.22 parts, 0.23 parts, 0.25 parts, 0.28 parts, and 0.3 parts. The light stabilizers, by weight, include, but are not limited to, point values ​​or ranges between any two of the following: 0.1 parts, 0.12 parts, 0.13 parts, 0.15 parts, 0.16 parts, 0.18 parts, and 0.2 parts.

[0064] Antioxidants can significantly improve the thermal and oxidative stability of thermoplastic polyurethane, thereby extending its service life. UV absorbers can significantly improve the light stability, durability, and service life of thermoplastic polyurethane, reducing the penetration and degradation of UV rays. Light stabilizers can prevent aging and discoloration of thermoplastic polyurethane, thus improving its light resistance.

[0065] In some specific embodiments, the antioxidant includes at least one selected from pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl)phosphite, n-octadecanoate, and N,N-bis-hexanediamine.

[0066] In some specific embodiments, the ultraviolet absorber includes at least one of Euwint UV absorber UV1, benzotriazole UV-921, and ultraviolet absorber UV-1300.

[0067] In some specific embodiments, the light stabilizer includes at least one of light stabilizer 770, nano-sized titanium dioxide, and hindered amine light stabilizer (HALS); preferably, light stabilizer 770.

[0068] The present invention further provides a method for preparing thermoplastic polyurethane, comprising the following steps: mixing the raw materials and carrying out a polycondensation reaction to obtain the thermoplastic polyurethane.

[0069] This preparation method is simple to operate, has a short process, and is easy to mass-produce.

[0070] In some specific embodiments, the method of mixing the raw materials and carrying out the polycondensation reaction specifically includes: mixing polycarbonate polyol and chain extender and performing vacuum dehydration, wherein the vacuum dehydration temperature is 100-120°C, the vacuum dehydration time is 1-4 hours, and the vacuum degree of vacuum dehydration is 665-1330 Pa; then adding reinforcing filler, polyisocyanate, and catalyst and stirring evenly; then reacting under vacuum conditions, and after the reaction is completed, pouring the resulting mixture into a mold for curing, wherein the reaction temperature is 90-120°C, the reaction time is 30-60 minutes, the curing temperature is 100-120°C, and the curing time is 2-4 hours; subsequently cooling to obtain the polyurethane. This is beneficial for improving reaction efficiency and promoting complete reaction.

[0071] In some specific embodiments, the method of mixing the raw materials and carrying out the polycondensation reaction specifically includes: mixing polycarbonate polyol and chain extender and performing vacuum dehydration, wherein the vacuum dehydration temperature is 100-120°C, the vacuum dehydration time is 1-4 hours, and the vacuum degree of vacuum dehydration is 665-1330 Pa; then adding antioxidant, ultraviolet absorber, light stabilizer, reinforcing filler, polyisocyanate, and catalyst, and stirring evenly; then reacting under vacuum conditions, and after the reaction is completed, pouring the resulting mixture into a mold for curing, wherein the reaction temperature is 90-120°C, the reaction time is 30-60 minutes, the curing temperature is 100-120°C, and the curing time is 2-4 hours; subsequently cooling to obtain the polyurethane. This is beneficial for improving reaction efficiency and promoting complete reaction.

[0072] The vacuum dehydration temperature includes, but is not limited to, any one of 100℃, 105℃, 110℃, 115℃, and 120℃, or a range between any two. The vacuum dehydration time includes, but is not limited to, any one of 1h, 2h, 3h, and 4h, or a range between any two. The vacuum degree of vacuum dehydration includes, but is not limited to, any one of 665Pa, 670Pa, 680Pa, 700Pa, 750Pa, 800Pa, 850Pa, 900Pa, 950Pa, 1000Pa, 1050Pa, 1100Pa, 1150Pa, 1200Pa, 1250Pa, 1300Pa, and 1330Pa, or a range between any two.

[0073] The reaction temperature includes, but is not limited to, any one of 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, and 120℃, or a range between any two. Within this temperature range, the reaction of the entire system can be activated, while the reaction rate can be controlled to prevent it from becoming too rapid.

[0074] The reaction time includes, but is not limited to, a point value of any one of 30 min, 40 min, 50 min, and 60 min, or a range of any two of them.

[0075] The curing temperature includes, but is not limited to, any one of 100℃, 105℃, 110℃, 115℃, and 120℃, or a range between any two. The curing time includes, but is not limited to, any one of 2h, 3h, and 4h, or a range between any two. Curing ensures complete polymerization: during curing, the chemical reactions within the polyurethane material continue, ensuring complete polymerization and forming a stable polymer structure. Curing also improves the mechanical strength of thermoplastic polyurethane.

[0076] In some specific embodiments, the vacuum dehydration is performed until the water content (i.e., the mass fraction of water) in both the polycarbonate polyol and the chain extender is less than 0.05 wt.%, including but not limited to point values ​​of any one of 0.04 wt.%, 0.03 wt.%, 0.02 wt.%, and 0.01 wt.%, or a range between any two.

[0077] The present invention further provides a thermoplastic polyurethane film prepared from the above-described thermoplastic polyurethane. Alternatively, the thermoplastic polyurethane film is prepared from thermoplastic polyurethane obtained according to the above-described method for preparing thermoplastic polyurethane.

[0078] It is understandable that thermoplastic polyurethane is in block or granular form, while thermoplastic polyurethane film is in sheet, layer, or film form.

[0079] This thermoplastic polyurethane film combines ultra-low resilience with high sand erosion resistance, which is conducive to the further promotion and application of thermoplastic polyurethane films. For example, it can be applied to the large and small curved surfaces of different blades. It solves the problem that existing thermoplastic polyurethane films have high resilience and poor sand erosion resistance, which limits their application.

[0080] In some specific embodiments, the thickness of the thermoplastic polyurethane film is 0.3 to 0.5 mm, including but not limited to any one of 0.3 mm, 0.33 mm, 0.35 mm, 0.38 mm, 0.4 mm, 0.42 mm, 0.45 mm, 0.48 mm, and 0.5 mm, or a range between any two.

[0081] The thermoplastic polyurethane film provided by this invention has a relatively thin thickness.

[0082] The present invention further provides a method for preparing the above-mentioned thermoplastic polyurethane film, comprising the following steps: crushing the thermoplastic polyurethane and granulating it to obtain polyurethane particles; casting the polyurethane particles to obtain the thermoplastic polyurethane film.

[0083] This invention involves crushing thermoplastic polyurethane into powder, granulating it, and then preparing a polyurethane film using a casting device. This method can obtain an integrally formed thermoplastic polyurethane film, which solves the problems of poor interlayer bonding and easy delamination that exist in multilayer polyurethane films due to adhesive bonding while ensuring high tensile strength.

[0084] Furthermore, this method is simple to operate, and the thermoplastic polyurethane film prepared by this method has a low thickness, good uniformity, and high elongation at break. It solves the problems of poor spraying uniformity, high film thickness, high film hardness, and high construction difficulty that exist in the existing technology of melting polyurethane semi-finished products and spraying them onto metal surfaces. It can be applied to large curved surface structural components such as propeller tips and radomes.

[0085] In some specific embodiments, the granulation temperature is 180 to 210°C, including but not limited to any one of 180°C, 190°C, 200°C, and 210°C, or a range between any two.

[0086] In some specific embodiments, a vacuum drying step is included after granulation and before casting. Vacuum drying can remove moisture from the polyurethane.

[0087] In some specific embodiments, the vacuum drying temperature is 60 to 90°C, including but not limited to any one of 60°C, 70°C, 80°C, and 90°C, or any range between two of them.

[0088] In some specific embodiments, the vacuum drying time is 20 to 24 hours, including but not limited to any one of 20 hours, 21 hours, 22 hours, 23 hours, and 24 hours, or any range between two of them.

[0089] In some specific embodiments, the preparation method of the thermoplastic polyurethane film provided by the present invention specifically includes: adding polycarbonate polyol and chain extender to a reaction vessel, heating to dehydrate under vacuum to reduce the moisture content of the raw materials; then purging nitrogen gas to release the vacuum, cooling to 70-90°C, and sequentially adding antioxidant, ultraviolet absorber, light stabilizer, and reinforcing filler, and stirring evenly; then rapidly adding diisocyanate and catalyst and stirring, followed by vacuum degassing, stirring for several minutes, and after the reaction is complete, pouring the reaction mixture into a polytetrafluoroethylene mold, curing, cooling, and removing it from the pan. The polyurethane is then mechanically crushed to obtain polyurethane flakes or powder. The polyurethane flakes or powder are then added to a twin-screw granulator for granulation to obtain functional polyurethane particles. Finally, the functional polyurethane particles are vacuum dried in an oven, and a polyurethane film with ultra-low resilience and high sand erosion resistance is prepared using a casting device. This is beneficial for improving the uniformity of the thermoplastic polyurethane film. See the schematic diagram of the preparation method. Figure 1 As shown. In some specific embodiments, the quality of the thermoplastic polyurethane film is controlled by mechanical crushing, twin-screw granulation, and casting with a casting machine.

[0090] The present invention also provides the application of the above-mentioned thermoplastic polyurethane, or the thermoplastic polyurethane prepared according to the above-mentioned method of preparing thermoplastic polyurethane, or the above-mentioned thermoplastic polyurethane film, or the thermoplastic polyurethane film prepared according to the above-mentioned method of preparing thermoplastic polyurethane film, in aircraft propeller blades, aircraft radomes, wind turbine blades, and front and rear bumpers of automobiles.

[0091] The thermoplastic polyurethane and thermoplastic polyurethane film provided by this invention, which combine ultra-low resilience and high sand erosion resistance, can be applied to drones and low-altitude aircraft in the aviation field, wind turbine blades in the wind power field, and front and rear bumper protective films in the automotive field, but are not limited thereto.

[0092] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0093] The sand erosion resistance test methods for the thermoplastic polyurethane films prepared in the following embodiments and the polyurethane films prepared in the comparative examples are as follows: Each thermoplastic polyurethane film or polyurethane film was attached to a standard plate and its performance was verified by sand erosion test. Specifically, the sand erosion conditions were defined based on the analysis of the sand erosion characteristics of low-altitude particulate matter on low-altitude aircraft in the actual environment. The conditions were: sand particle diameter of 0.2 to 0.6 mm, sand drop rate of 0.038 g / s, angle of attack of the eroded part of 10°, and sand particle velocity of 170 m / s. The state of the thermoplastic polyurethane film or polyurethane film was observed in real time. If the substrate was exposed, the test was stopped and the failure time was recorded.

[0094] The tensile strength and elongation at break of the thermoplastic polyurethane films prepared in the following examples and the polyurethane films prepared in the comparative examples were tested according to GB528-2009; the air oven aging test was conducted according to GB / T2951.11-2008, under the condition of 110℃ for 168 hours; the shrinkage rate was measured after 24 hours using a 5cm×15cm specimen at a speed of 300mm / min and a constant elongation of 200%.

[0095] Example 1

[0096] The method for preparing thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment includes the following steps:

[0097] (1) Preparation of thermoplastic polyurethane: 50 parts by weight of polyhexamethylene carbonate diol with a molar mass of 2000 g / mol and 4 parts by weight of 1,4-butanediol were added to a reaction vessel, heated to 110°C, and vacuum dehydrated for 2 h with a vacuum degree of 1000 Pa, so that the moisture content in both polytetramethylene carbonate diol and 1,4-butanediol was less than 0.05 wt.%. Nitrogen gas was then introduced to release the vacuum, and the mixture was cooled to 80°C. 0.1 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite, 0.25 parts by weight of UV absorber UV-1300, 0.15 parts by weight of light stabilizer 770, and 0.07 parts by weight of micron-sized silica (median particle size 500 μm) were added sequentially and stirred until homogeneous. Then, 25 parts by weight of diphenylmethane diisocyanate and 0.02 parts by weight of dibutyltin dilaurate were quickly added and stirred until homogeneous. The mixture was then degassed under vacuum and stirred at 100°C for 40 minutes. The resulting mixture was poured into a polytetrafluoroethylene mold and cured at 110°C for 3 hours. After cooling, the mixture was removed from the mold to obtain thermoplastic polyurethane (bulk).

[0098] (2) Preparation of thermoplastic polyurethane film: The thermoplastic polyurethane obtained in step (1) is mechanically crushed to obtain polyurethane powder, which is then added to a twin-screw granulator for granulation at a temperature of 170℃ to obtain functional polyurethane particles. The functional polyurethane particles are then vacuum dried in an oven at 80℃ for 24 hours and cast using a casting machine to prepare a thermoplastic polyurethane film with ultra-low resilience and high sand erosion resistance. The thickness of this thermoplastic polyurethane film is 0.4 mm.

[0099] Comparative Example 1

[0100] The preparation method of the polyurethane and polyurethane film provided in this comparative example is basically the same as that in Example 1, except that in step (1), polyhexamethylene carbonate diol is replaced with polycaprolactone polyol (polyester polyol) in equal parts by weight and equal molar mass.

[0101] Comparative Example 2

[0102] The preparation method of the polyurethane and polyurethane film provided in this comparative example is basically the same as that in Example 1, except that in step (1), polyhexamethylene carbonate diol is replaced with polytetrahydrofuran alcohol (polyether polyol) in equal parts by weight and equal molar mass.

[0103] The test results of the thermoplastic polyurethane film prepared in Example 1 and the polyurethane films prepared in Comparative Examples 1 and 2 are shown in Table 1 below.

[0104] Table 1 Comparison of test results of Example 1 and Comparative Examples 1-2

[0105]

[0106]

[0107] As can be seen from Table 1, under the condition that other conditions remain unchanged, the thermoplastic polyurethane films prepared by adding different types of polyols have different shrinkage rates, tensile strengths, elongation at break, tensile strength under air heat aging test, stress at 200% constant elongation, and sand erosion resistance time.

[0108] Specifically, the shrinkage rate of the thermoplastic polyurethane film prepared by polycarbonate polyol (Example 1) was significantly lower than that of polycaprolactone polyol (Comparative Example 1) and polytetrahydrofuran alcohol (Comparative Example 2); furthermore, the tensile strength, elongation at break, and tensile strength in air heat aging tests of the thermoplastic polyurethane film prepared by polycarbonate polyol were all higher than those of polycaprolactone polyol and polytetrahydrofuran alcohol. For protective films of low-altitude aircraft, the thermoplastic polyurethane film prepared by polycarbonate polyol exhibits excellent tensile strength and significantly improved sand erosion resistance.

[0109] Example 2

[0110] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 1. The difference is that in step (1), polyhexamethylene carbonate diol is replaced with an equal part by weight of polytetramethylene carbonate diol, and its molar mass is 1000 g / mol.

[0111] Example 3

[0112] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 2. The difference is that in step (1), the molar mass of polytetramethylene carbonate diol is replaced with 2000 g / mol.

[0113] Example 4

[0114] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 2. The difference is that in step (1), the molar mass of polytetramethylene carbonate diol is replaced with 3000 g / mol.

[0115] The test results of the thermoplastic polyurethane films prepared in Examples 2 to 4 are shown in Table 2 below.

[0116] Table 2 Comparison of test results in Examples 2-4

[0117]

[0118] As shown in Table 2, under otherwise constant conditions, with the increase of the molar mass of the polycarbonate polyol, the shrinkage rate increases, while the tensile strength, air-heat aging tensile strength, and sand erosion resistance increase, and the elongation at break decreases. Therefore, to balance ultra-low resilience and high sand erosion resistance, a polycarbonate polyol with a molar mass of 1500–2500 g / mol is preferred. Alternatively, a polycarbonate polyol with a lower shrinkage rate or higher sand erosion resistance can be selected as needed.

[0119] Example 5

[0120] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 1. The difference is that in step (1), polyhexamethylene carbonate diol is replaced with polycarbonate diol of equal molar mass, and the weight of polycarbonate diol is 40 parts by weight.

[0121] Example 6

[0122] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 5. The difference is that in step (1), the weight parts of polycarbonate diol are replaced with 50 parts by weight.

[0123] Example 7

[0124] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 5. The difference is that in step (1), the weight parts of polycarbonate diol are replaced with 60 weight parts.

[0125] Comparative Example 3

[0126] The preparation method of the polyurethane and polyurethane film provided in this comparative example is basically the same as that in Example 5, except that in step (1), the weight parts of polycarbonate diol are replaced with 30 parts by weight.

[0127] Comparative Example 4

[0128] The preparation method of the polyurethane and polyurethane film provided in this comparative example is basically the same as that in Example 5, except that in step (1), the weight parts of polycarbonate diol are replaced with 70 parts by weight.

[0129] The test results of the thermoplastic polyurethane films prepared in Examples 5 to 7 and the polyurethane films prepared in Comparative Examples 3 to 4 are shown in Table 3 below.

[0130] Table 3 Comparison of test results for Examples 5-7 and Comparative Examples 3-4

[0131]

[0132]

[0133] As shown in Table 3, with the increase of the weight parts of polycarbonate polyol, the shrinkage rate increases, and the tensile strength and tensile strength in the air heat aging test increase, while the elongation at break, 200% constant elongation stress, and sand erosion resistance decrease. Therefore, in order to balance ultra-low resilience, high sand erosion resistance, and high tensile strength, the weight parts of polycarbonate polyol should be controlled at 40-60 parts by weight.

[0134] Specifically, compared to Example 5, Comparative Example 3 had lower tensile strength and air-heat aging tensile strength due to the excessively low weight percentage of polycarbonate polyol. Furthermore, the residual isocyanate may release toxic substances, especially under high temperature or hydrolysis conditions, affecting the material's safety. Residual monomers can also lead to decreased material stability, potentially causing performance degradation or environmental pollution during long-term use.

[0135] Compared with Example 5, Comparative Example 4 had an excessively high weight percentage of polycarbonate polyol, resulting in an increased shrinkage rate, reduced sand erosion resistance, slower reaction rate, incomplete polymer reaction, and a softer polymer.

[0136] Example 8

[0137] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 1. The difference is that in step (1), the weight of micron-sized silica is replaced with 0.1 parts by weight.

[0138] Comparative Example 5

[0139] The preparation method of the polyurethane and polyurethane film provided in this comparative example is basically the same as that in Example 8, except that micron-sized silica is not added in step (1).

[0140] Comparative Example 6

[0141] The preparation method of the polyurethane and polyurethane film provided in this comparative example is basically the same as that in Example 8, except that in step (1), the weight parts of micron-sized silica are replaced with 0.2 parts by weight.

[0142] The test results of the thermoplastic polyurethane film prepared in Example 8 and the polyurethane films prepared in Comparative Examples 5 to 6 are shown in Table 4 below.

[0143] Table 4 Comparison of test results of Example 8 and Comparative Examples 5-6

[0144]

[0145] As shown in Table 4, with the increase of the weight fraction of micron-sized silica, the shrinkage rate decreases, the tensile strength and air heat aging test tensile strength increase, the elongation at break decreases, the 200% constant elongation stress decreases, and the sand erosion resistance increases.

[0146] Specifically, compared with Example 8, Comparative Example 5 had a higher shrinkage rate and lower sand erosion resistance due to the absence of micron-sized silica.

[0147] Compared with Example 8, Comparative Example 6 had an excessive amount of micron-sized silica, which caused the polyurethane film to become brittle and the elongation at break to decrease, making it unsuitable for application to the large curved parts of the blade.

[0148] Example 9

[0149] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 1. The difference is that in step (1), micron-sized silica is replaced with an equal weight of micron-sized mica powder, and the median particle size of the micron-sized mica powder is 100 μm.

[0150] Example 10

[0151] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 9. The difference is that in step (1), the median particle size of micron mica powder is replaced with 500 μm.

[0152] Example 11

[0153] The preparation method of thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment is basically the same as that in Example 9. The difference is that in step (1), the median particle size of micron mica powder is replaced with 1000 μm.

[0154] The test results of the thermoplastic polyurethane films prepared in Examples 9 to 11 are shown in Table 5 below.

[0155] Table 5 Comparison of test results in Examples 9-11

[0156]

[0157] As shown in Table 5, by controlling the median particle size of the reinforcing filler within the range of 100 μm to 1000 μm, this invention enables the reinforcing filler to be uniformly dispersed within the polyurethane particles, thereby improving the shrinkage rate, tensile strength, and sand erosion resistance of the thermoplastic polyurethane film. Specifically, if the median particle size of the reinforcing filler is less than 100 μm, agglomeration is likely to occur, resulting in poor erosion resistance in localized areas of the protective film. If the median particle size of the reinforcing filler is greater than 1000 μm, the dispersion performance decreases, and the reinforcing filler disrupts the cohesive forces between polyurethane molecules, leading to increased brittleness of the film.

[0158] Example 12

[0159] The method for preparing thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment includes the following steps:

[0160] (1) Preparation of thermoplastic polyurethane: 45 parts by weight of polyhexamethylene carbonate diol with a molar mass of 2000 g / mol and 2 parts by weight of hydroquinone were added to a reaction vessel, heated to 100°C, and vacuum dehydrated for 4 h with a vacuum degree of 1300 Pa, so that the moisture content in both polytetramethylene carbonate diol and hydroquinone was less than 0.05 wt.%. Nitrogen gas was then introduced to release the vacuum, and the mixture was cooled to 80°C. 0.06 parts by weight of n-octadecyl alcohol ester and N,N-bis-hexanediamine, 0.3 parts by weight of Euwende UV absorber UV1, 0.2 parts by weight of light stabilizer 770, and 0.05 parts by weight of micron-sized corundum (median particle size 700 μm) were added sequentially and stirred until homogeneous. Then, 20 parts by weight of diphenylmethane diisocyanate and 0.01 parts by weight of dibutyltin dilaurate were rapidly added and stirred until homogeneous. The mixture was then degassed under vacuum and stirred at 90°C for 30 minutes. The resulting mixture was poured into a polytetrafluoroethylene mold and cured at 100°C for 4 hours. After cooling, the mixture was removed from the mold to obtain thermoplastic polyurethane (bulk).

[0161] (2) Preparation of thermoplastic polyurethane film: The thermoplastic polyurethane obtained in step (1) is mechanically crushed to obtain polyurethane powder, which is then added to a twin-screw granulator for granulation at a temperature of 210℃ to obtain functional polyurethane particles. The functional polyurethane particles are then vacuum dried in an oven at 60℃ for 22 hours and cast using a casting machine to prepare a thermoplastic polyurethane film with ultra-low resilience and high sand erosion resistance. The thickness of this thermoplastic polyurethane film is 0.3 mm.

[0162] Example 13

[0163] The method for preparing thermoplastic polyurethane and thermoplastic polyurethane film provided in this embodiment includes the following steps:

[0164] (1) Preparation of thermoplastic polyurethane: 55 parts by weight of polyhexamethylene carbonate diol with a molar mass of 2000 g / mol and 6 parts by weight of trimethylolpropane were added to a reaction vessel, heated to 120°C, and vacuum dehydrated for 1 h, wherein the vacuum degree was 700 Pa, so that the moisture content in both polytetramethylene carbonate diol and trimethylolpropane was less than 0.05 wt.%. Nitrogen gas was then introduced to release the vacuum, and the mixture was cooled to 80°C. Then, 0.15 parts by weight of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid], 0.2 parts by weight of benzotriazole UV-921, 0.1 parts by weight of nano-sized titanium dioxide, and 0.03 parts by weight of micron-sized quartz sand (median particle size 300 μm) were added sequentially and stirred until homogeneous. Subsequently, 30 parts by weight of diphenylmethane diisocyanate and 0.03 parts by weight of dibutyltin dilaurate were quickly added and stirred until homogeneous. The mixture was then degassed under vacuum and stirred at 120°C for 60 minutes. The resulting mixture was poured into a polytetrafluoroethylene mold and cured at 120°C for 2 hours. After cooling, the mixture was removed from the mold to obtain thermoplastic polyurethane (block).

[0165] (2) Preparation of thermoplastic polyurethane film: The thermoplastic polyurethane obtained in step (1) is mechanically crushed to obtain polyurethane powder, which is then added to a twin-screw granulator for granulation at a temperature of 180℃ to obtain functional polyurethane particles. The functional polyurethane particles are then vacuum dried in an oven at 90℃ for 20 hours, and then cast using a casting machine to prepare a thermoplastic polyurethane film with ultra-low resilience and high sand erosion resistance. The thickness of this thermoplastic polyurethane film is 0.5 mm.

[0166] The test results of the thermoplastic polyurethane films prepared in Examples 12 and 13 are shown in Table 6 below.

[0167] Table 6 Comparison of test results from Examples 12-13

[0168]

[0169] As shown in Table 6, the raw material composition and preparation parameters of thermoplastic polyurethane films also have a certain impact on their performance. This invention precisely controls the film quality, such as tensile strength and elongation at break, through mechanical crushing, twin-screw granulation, and casting with a casting machine.

[0170] Comparative Example 7

[0171] The polyurethane film provided in this comparative example is 3M's polyurethane protective film 8681HS, which was tested to have a sand erosion resistance of 140 min.

[0172] Comparative Example 8

[0173] The polyurethane film provided in this comparative example is 3M's polyurethane protective film 8663, which was tested to have a sand erosion resistance of 130 minutes.

[0174] The test results of the polyurethane films of Comparative Example 7 and Comparative Example 8 are shown in Table 7 below.

[0175] Table 7 Comparison of test results for Comparative Examples 7 and 8

[0176]

[0177] By comparing the performance test data of each embodiment and comparative examples 7-8, it can be seen that, compared with existing commercial polyurethane protective films, the thermoplastic polyurethane film prepared by the present invention has both ultra-low resilience and high sand erosion resistance, wherein the shrinkage rate is no higher than 10%, the sand erosion resistance time is significantly improved, and can even reach more than 3 times. Furthermore, the functional performance of the polyurethane film prepared in each embodiment is also greatly improved, with high tensile strength, high elongation at break, and high tensile strength in air heat aging test.

[0178] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A thermoplastic polyurethane, characterized in that, It is mainly composed of the following components in parts by weight: 40-60 parts of polycarbonate polyol, 20-30 parts of polyisocyanate, 2-6 parts of chain extender, 0.05-0.1 parts of reinforcing filler, and 0.01-0.03 parts of catalyst.

2. The thermoplastic polyurethane according to claim 1, characterized in that, The molar mass of the polycarbonate polyol is 1000–3000 g / mol.

3. The thermoplastic polyurethane according to claim 1, characterized in that, The polycarbonate polyol includes at least one of polytetramethylene carbonate diol, polyhexamethylene carbonate diol, and polycarbonate diol.

4. The thermoplastic polyurethane according to claim 1, characterized in that, The median particle size of the reinforcing filler is 100–1000 μm.

5. The thermoplastic polyurethane according to claim 1, characterized in that, At least one of the following conditions must be met: (1) The polyisocyanate includes diphenylmethane diisocyanate; (2) The chain extender includes at least one of ethylene glycol, 1,4-butanediol, hydroquinone, glycerol, trimethylolpropane and sorbitol; (3) The reinforcing filler includes at least one of silica, mica powder, quartz sand, corundum and corundum; (4) The catalyst includes at least one of dibutyltin dilaurate, triethylenediamine and N-dimethylethanolamine.

6. The thermoplastic polyurethane according to any one of claims 1 to 5, characterized in that, The components also include, by weight, 0.05 to 0.15 parts of antioxidant, 0.2 to 0.3 parts of ultraviolet absorber, and 0.1 to 0.2 parts of light stabilizer.

7. The thermoplastic polyurethane according to claim 6, characterized in that, The antioxidants include at least one of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris(2,4-di-tert-butylphenyl)phosphite, n-octadecanoate, and N,N-bis-hexanediamine; The ultraviolet absorber includes at least one of Euwint UV absorber UV1, benzotriazole UV-921, and ultraviolet absorber UV-1300; The light stabilizer includes at least one of light stabilizer 770, nano-sized titanium dioxide, and hindered amine light stabilizers.

8. The method for preparing the thermoplastic polyurethane according to any one of claims 1 to 7, characterized in that, The process includes the following steps: mixing the raw materials and carrying out a polycondensation reaction to obtain the thermoplastic polyurethane.

9. The method for preparing thermoplastic polyurethane according to claim 8, characterized in that, The method of mixing the raw materials and carrying out a polycondensation reaction specifically includes: Polycarbonate polyol and chain extender are mixed and vacuum dehydrated, wherein the vacuum dehydration temperature is 100-120°C, the vacuum dehydration time is 1-4 hours, and the vacuum degree of the vacuum dehydration is 665-1330 Pa. Add reinforcing filler, polyisocyanate and catalyst to it and stir until homogeneous; The reaction is carried out under vacuum conditions. After the reaction is completed, the resulting mixture is poured into a mold for maturation. The reaction temperature is 90-120°C, the reaction time is 30-60 min, the maturation temperature is 100-120°C, and the maturation time is 2-4 h. The polyurethane is obtained after cooling.

10. The method for preparing thermoplastic polyurethane according to claim 8, characterized in that, The method of mixing the raw materials and carrying out a polycondensation reaction specifically includes: Polycarbonate polyol and chain extender are mixed and vacuum dehydrated, wherein the vacuum dehydration temperature is 100-120°C, the vacuum dehydration time is 1-4 hours, and the vacuum degree of the vacuum dehydration is 665-1330 Pa. Add antioxidants, UV absorbers, light stabilizers, reinforcing fillers, polyisocyanates, and catalysts to the mixture and stir until homogeneous; The reaction is carried out under vacuum conditions. After the reaction is completed, the resulting mixture is poured into a mold for maturation. The reaction temperature is 90-120°C, the reaction time is 30-60 min, the maturation temperature is 100-120°C, and the maturation time is 2-4 h. The polyurethane is obtained after cooling.

11. A thermoplastic polyurethane film, characterized in that, It is prepared from the thermoplastic polyurethane as described in any one of claims 1 to 7, or from the thermoplastic polyurethane prepared by the method described in any one of claims 8 to 10.

12. The thermoplastic polyurethane film according to claim 11, characterized in that, The thickness of the thermoplastic polyurethane film is 0.3 to 0.5 mm.

13. The method for preparing the thermoplastic polyurethane film as described in claim 11, characterized in that, Includes the following steps: The thermoplastic polyurethane is crushed and then granulated to obtain polyurethane particles; The polyurethane particles are cast to obtain the thermoplastic polyurethane film.

14. The method for preparing the thermoplastic polyurethane film according to claim 13, characterized in that, The granulation temperature is 180–210°C.

15. The method for preparing the thermoplastic polyurethane film according to claim 13, characterized in that, After granulation and before casting, a vacuum drying step is included; wherein the vacuum drying temperature is 60-90°C and the vacuum drying time is 20-24 hours.

16. The thermoplastic polyurethane as described in any one of claims 1 to 7, or the thermoplastic polyurethane prepared by the method of preparing the thermoplastic polyurethane as described in any one of claims 8 to 10, or the thermoplastic polyurethane film as described in any one of claims 11 to 12, or the thermoplastic polyurethane film prepared by the method of preparing the thermoplastic polyurethane film as described in any one of claims 13 to 15, in the application of aircraft propeller blades, aircraft radomes, wind turbine blades, and front and rear bumpers of automobiles.

Images