TPU Chinese name is thermoplastic polyurethane elastomer, which is formed by the co-reaction and polymerization of diisocyanate molecules such as diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) and macromolecular polyols and low molecular polyols (chain extenders). of polymer compounds. TPU can be heated and plasticized, and has no or little cross-linking in its chemical structure. Its molecules are basically linear, but there are certain physical cross-linking, mainly divided into polyester type and polyether type. It is a new type of organic Polymer compound materials. It has a wide range of hardness (60HA-85HD), wear resistance, oil resistance, transparency, and good elasticity. It is a kind of excellent performance and can replace rubber and soft PVC materials. Its excellent physical properties, such as wear resistance and resilience, are better than ordinary polyurethane and PVC, and its aging resistance is better than rubber. It is a kind of polymer material between rubber and plastic. It is used in daily necessities, sporting goods, toys, decorative materials, etc. It can be said that it is the most ideal material to replace PVC and PU to meet the environmental protection requirements of more and more fields. Internationally known as a new type of environmentally friendly polymer material.

1. The origin of TPU

TPU was first successfully developed by the German Bayer company and started industrial production, and then other major companies began to produce it one after another. It has a history of more than 50 years. In Asia, Japan was the first region to introduce German TPU production technology, and then in the 1980s, Taiwan introduced this technology from Japan and began industrial production. From the 1970s and 1980s, our mainland area has initially mastered the continuous production and synthesis technology of TPU twin-screw method through the "Seventh Five-Year Research" in the last century. Therefore, production in our mainland has been hovering at a low level, and research has not made much progress, and the level of R&D and production has been lagging behind that of foreign-funded enterprises and Taiwan-funded enterprises. After this century, with the landing of major Taiwanese companies, TPU production in the mainland has been vigorously developed.

2. Development of technology and applications

The structural formula of TPU consists of two parts, one part is a rigid block obtained by the reaction of diisocyanate molecules with a chain extender, and the other part is a flexible block obtained by the reaction between diisocyanate molecules and macromolecular polyols. The two parts are alternately inlaid with each other to form the whole TPU. TPU material has strong high tension, high tensile force, toughness and aging resistance, and it can produce various products by general plastic processing methods, waste can be recycled, and additives and fillers can be widely used to improve Certain physical properties, processing properties or cost reduction, it is an environmentally friendly new material with a wide range of practicability. At present, TPU has been used in medical and health, electronic appliances, industry and sports, etc. It has the characteristics of high strength, toughness, wear resistance, cold resistance, oil resistance, water resistance, aging resistance and climate change resistance that other plastic materials cannot reach. , At the same time, it also has many excellent functions of high waterproof and moisture permeability, windproof, coldproof, antibacterial, mildewproof, warm, anti-ultraviolet and energy release.

TPU can be mainly divided into polyester type and polyether type according to the soft segment structure. Polyester type contains ester group with higher cohesive energy, the product has higher mechanical properties, moderate cost, but poor water resistance. The polyether type has no ester group and contains free-placed ether bonds, showing good low temperature flexibility and water resistance, but poor mechanical strength and heat resistance. The polyglycolactone type is between polyester and polyether, and has good comprehensive performance, but the price is relatively high. According to our own needs, we can change the formula configuration to make TPU with required performance. The existing TPU production technology has developed rapidly, and the original TPU raw materials have been modified in various ways to make it more and more widely used.

The synthesis reaction of TPU materials is relatively complicated, but the most basic reaction for synthesizing TPU is the reaction of polyols and isocyanates to generate urethane groups. The structural segment containing urethane group is a repeating unit, and long-chain polyol and short-chain polyol are combined to form a molecular chain structure with hard segments and soft segments, which is the basic structure of TPU. The macromolecular polyol is connected with the isocyanate to form a long molecular chain. Because the molecular chain is long and flexible, it becomes a soft segment structure in the entire molecular chain. Short-chain diols and isocyanates are connected to form a short-chain structure, and similarly, they become a hard segment structure in the molecular chain. Such a special structure between hard and soft endows TPU with both elasticity and good mechanical properties, as well as the special properties of thermoplastic processing. It can be seen that for different macromolecular polyols, the selection of chain extenders and polyisocyanates can produce a wide variety of TPU products with different properties.

The direction of production and improvement of existing TPU materials is mostly the difference in raw materials, proportions, or the addition of some auxiliary materials. At present, the best way to produce ordinary TPU materials is to use a twin-screw extruder in one step. The TPU prepared by the one-step method is basically a block linear polymer. The process steps are composed of four parts: raw material preparation, metering and conveying, mixing reaction, extrusion and granulation. The advantages of this method are accurate metering of raw materials, uniform mixing, uniform reaction temperature and uniform residence time of materials in the machine. In the production process, the control of raw material moisture, measurement accuracy, transportation, temperature distribution and pelletizing technology must be strictly controlled. At the same time, according to the needs, through the adjustment of the formula, the TPU with the required physical properties can be obtained. The main consideration for the improvement of the original TPU technology now is the physical and mechanical properties of the TPU material, various resistances, environmental protection and cost savings. The physical and mechanical properties of TPU materials are directly related to the quality and proportion of raw materials. Before the raw materials are melted at high temperature, the purity, temperature, dryness, uniformity of mixing, proportion, and synthetic hard and soft segment content of the raw materials must be guaranteed. The mechanical design requirements for production are very high. In addition, the addition of various additives is also an important technical means to improve the performance of TPU materials. The choice of catalyst has a huge impact on the performance of TPU materials. Different types of catalysts are selected, different amounts of catalysts are added, and different addition times and temperatures have been proved to have a huge impact on the performance of TPU. Various other fillers will also have a huge impact on the performance of TPU. With the continuous development of TPU production technology, the market will have higher and higher requirements for cost control and appearance of TPU products, as well as higher and higher performance requirements, which also makes TPU production technology continue to develop.

The development of TPU production technology, the maturity of production technology, and the continuous improvement of TPU performance have made it available in different fields. Then, since PVC and other polyvinyl chloride polymers were banned by the European Union and other developed countries, TPU, as an alternative with excellent performance, environmental protection and pollution-free, gained a larger application market.

The application of TPU materials has penetrated into almost every industrial field, such as construction, automobile manufacturing, shock-proof buffer materials, paving materials, tanning, medical and health care, etc., and there are many potential fields to be developed.

TPU materials are mainly used in the following aspects:

1. Film and sheet Polyurethane film is mainly prepared by extrusion, calendering and blow molding, the thickness is from a few microns to a few millimeters, and various colors can be obtained by adding pigments. Due to the characteristics of polyurethane molecular structure, people can change its elasticity, hardness and hydrophilicity by adjusting the proportion of polyurethane block components. Therefore, polyurethane film has excellent high tension, high tensile force, toughness and aging resistance like polyurethane elastomer. At the same time, it has excellent biological and blood compatibility and chemical resistance, and is widely used in medical and health, high-end textile fabrics, industry and other fields. Polyether TPU can also be used to produce waterproof, moisture-permeable and breathable films, which are environmentally friendly, breathable, and waterproof. The thickness of TPU film ranges from several microns to several millimeters, and there are high, medium and low moisture permeability films, which are widely used in various fields such as packaging, garment lamination, shoulder straps and shoe materials. Such as sports shoes, hiking shoes, snowshoes, golf shoes, roller skates and other footwear fabrics and lining materials, the breathable moisture permeability and low temperature flexibility of TPU film can give footwear unparalleled comfort. In the medical and health field, thermoplastic polyurethane films are mainly used, such as surgical gowns, medical gloves, medical mattresses, ice packs, bandages, plasma tapes, condoms, wound dressings, artificial organs, etc. Waterproof and breathable polyurethane medical gloves provide excellent water vapor permeability, bacteria resistance and comfort. Traditional wound dressings have many shortcomings, but the use of polyurethane microporous and hydrophilic membranes can make the wound dressings have good ventilation and absorption functions, and the good biocompatibility of polyurethane can also be used as transdermal dressings, which can effectively block drugs. The unnecessary diffusion of active ingredients can also ensure that the active ingredients act on the skin at a certain rate. At present, it has been used in Daliang abroad, and it is expected that we will have a huge market in the future. Polyurethane film is optically transparent, soft to the touch, highly stretchable, durable and easy to process, and waterproof and breathable. It is widely used in daily life as a high-grade or special textile fabric. The use of polyurethane film as a medical clothing fabric has the advantages of breathable, antibacterial, anti-liquid permeation, no degradation under long-term washing and steam sterilization conditions, and reasonable price. The earliest polyurethane films and coatings were first used in the clothing of outdoor workers engaged in agriculture, construction, forestry, mountaineering and marine and air rescue, and then gradually expanded to footwear. At present, polyurethane is widely used in footwear, such as all kinds of shoes, especially sports shoes or special functional footwear fabrics and lining materials; Clothing made of breathable polyurethane film material not only breathes, but also resists static electricity. 
Specialized TPU can also meet the requirements of the German Health Commission for food contact materials, as well as the relevant requirements of the US Food and Drug Administration.

2. TPU composite leather polyurethane film is used to produce composite fabrics. As a home apparel fabric, it can play a protective role at room temperature, and can have good moisture permeability above room temperature. In the industrial field, polyurethane composite leather is often used as fire protection, heat insulation, sound insulation materials, aircraft parts and decoration, auto parts and waterproof tapes, compression seals, conveyor belts, insulating panels, and safety bulletproof glass. For example, the United States makes it into a car care film product, which is used for covering the front edge of the hood, the front and rear bumpers of the car, the lower door panel, the door lock handle, etc., to avoid being hit by stones and friction to protect the surface paint of the car. TPU composite leather generally has good optical transparency and light stability. Many manufacturers in my country also use imported polyurethane films to package and protect the interior and exterior of automobiles. The United Kingdom has developed a bulletproof glass for aircraft boxes and bulletproof cars, which is composited with multiple layers of polyurethane films. In addition, polyurethane-based plastic film composite leather is also used in the mold industry, metal and weapon corrosion protection.

3. TPU pipe

TPU can be made into many different types of tubing. Polyetherester type and polyether type TPU have a series of advantages such as high elongation and good resistance to hydrolysis and microorganisms, excellent mechanical properties (tensile strength and tear strength), etc., so they are suitable for the interior of fire water pipes. lining. This kind of fire hose is lighter than the traditional fire hose and is easier to operate and use. The pipe with TPU as the inner layer is very useful when conveying sand and stone slurry. Its good wear resistance and puncture resistance make the pipe life relatively long and save materials. TPU hoses have softness, good tensile strength, impact strength and high temperature resistance, so in China, TPU hoses are mostly used for gas and oil transportation of aircraft, tanks, automobiles, motorcycles, machine tools, etc.

4. TPU shoe material

Because TPU has relatively high wear resistance, puncture resistance, longitudinal bending strength and low temperature impact strength, it is often used in the outer material of ski boots. The tear resistance and crack propagation resistance of TPU are among the best among plastic materials. For example, ski boots often use TPU with Shore hardness of 50D~66D and Young's modulus of 100~600MPa, and select appropriate TPU grades according to the performance requirements of different parts. Skating shoes are also commonly made of TPU, because TPU has high low temperature impact resistance. The soles of many sports shoes are made of TPU materials, especially in football shoes. Polyester TPU with Shore hardness 85A~90A is commonly used because of its excellent wear resistance and cutting resistance. And TPU material can also be made very soft and elastic, and the comfort of the inner lining and insole of the shoe will be higher than other materials, so it is widely used in sports shoes and casual shoes.

5. Auto parts

Because TPU has good resilience, cutting resistance, weather resistance, and oil resistance, it is very suitable for the automotive industry and has become one of the most widely used plastics in automobiles. According to different automotive components, TPU has different forms and properties such as foam plastics, elastomers, and adhesives to meet the requirements of automobiles. For example, TPU foam plastics have the advantages of light weight, heat insulation, good resilience and comfort with the change of formula. , Good low temperature performance, durability, safety and high shock absorption, its superiority is incomparable with other materials. BASF has developed Elastoskin, a TPU skin material used for automotive interior decoration, which is used for the surface layer of dashboard and door panel interior parts. The use of skin materials such as PVC is still low, and it is an ideal substitute for PVC. TPU can also be used as other components of automobiles, such as bumpers, skeleton materials, instrument panels, shock absorbers and other parts. A polyurethane structure reflection molding (SRIM) technology has been widely used in Europe and the United States, which can effectively reduce the quality of parts. The technological process is: first preform the skin, put the glass fiber mat into the mold, and then inject the polyurethane resin, and then cure and form (micro-foaming). A variety of automotive trim parts can be produced with this process, such as door trim panels, coat racks, instrument panel skeletons, and roof studs. The advantage of SRIM is that it can flexibly design wall thickness, radian or reinforcing ribs according to the different mechanical properties of the parts. Compared with products such as injection molding, SRIM has lower interior noise, and can also improve the physical properties of the product, such as lower density, higher elongation, less odor and mildew problems, etc., creating a comfortable interior. environment.

6. Medical and health care

TPU has high compatibility with human skin, and polyether TPU has good compatibility with human blood and tissue, so TPU tubes can be used to make blood vessels, and even microporous, biodegradable, Flexible, blood-compatible artificial blood vessels. Now with the development of medicine, TPU products are also used as materials for artificial organs because of their excellent properties. Its products include artificial heart valves, artificial lungs, artificial skin, burn dressings, bone adhesives, and pacemaker insulation. Threads, sutures, various splints, catheters, artificial blood vessels, trachea, intubation, dental materials, family planning supplies, etc. For example, human prostheses made of polyester TPU copolymers have good compatibility with human tissues. For example, the PU microcellular elastomer made of polyester-MDI foam can be used to make prosthetics; water-foamed TPU can be used to make prosthetic sheaths, and its wear resistance exceeds that of latex sheaths; upper limbs are made of polyether polyol and TDI in one step. Microcellular elastomer, and the palm and finger parts that require abrasion resistance and flexion resistance are prepared by semi-prepolymerization with polyester polyol and MDI as the main raw materials. Replacing the original PVC-coated latex glove material with TPU material eliminates most of the noise of the electric prosthetic hand and saves power. Fracture patients are generally fixed with plaster bandages, but plaster has disadvantages such as heavy weight, low strength, and poor air permeability. Researchers at home and abroad are committed to the study of more ideal orthopedic materials. Bandages made of polyurethane materials can not only avoid moisture and The resulting complications have the characteristics of plaster bandages, and are stronger than plaster bandages. Its strength is 20 times that of plaster bandages. It can withstand the strength of human muscle deformation due to force. Long-term bandage is not deformed, wear-resistant, the material is relatively low in density, has a certain air permeability, can pass through the water evaporated by the skin, can prevent itching, odor and infection of skin bacteria, thereby avoiding the occurrence of skin atrophy. The structure is stable, it is not afraid of water immersion and liquid erosion, it will not burn, and the molding conditions are not harsh. The scope of use and operation method are similar to those of plaster bandages. Hygienic, fast curing, light and thin, tough and tough, not easy to inflame wounds, has the characteristics of good air permeability, strong stiffness, water immersion, and X-ray penetration. It can be used as fixation in trauma orthopedic treatment and orthopedic treatment. material, its comprehensive performance is obviously better than that of plaster bandages. 

TPU material has become the best substitute for human tissue because of its breathability, high elasticity and high biocompatibility. With the advancement of medicine in the future, TPU will also play a great role in medical and health care.

7. TPU adhesive

TPU adhesive is a kind of polyurethane adhesive. It is now widely used in the surface treatment of nylon, polyester and PU fabrics and leather. It has the characteristics of chemical resistance, UV resistance, hydrolysis resistance, good low temperature flexibility, and good bending fatigue performance. TPU adhesive has excellent rubber properties and can adapt to the bonding of substrates with different thermal expansion coefficients. It forms a soft-hard transition layer between the substrates, which not only has strong adhesion, but also has excellent buffering, reducing shock function. The low temperature and ultra-low temperature properties of TPU adhesives exceed all other types of adhesives. According to different uses, TPU adhesives can be divided into polyurethane adhesives for automobiles, polyurethane adhesives for wood, polyurethane adhesives for shoes, polyurethane adhesives for packaging, polyurethane adhesives for construction, polyurethane adhesives for inks, and polyurethane adhesives for book binding, etc. It plays an important role in daily life and industrial production. TPU adhesives can also be mixed with pigments and solvents to form varnishes and inks, which can be sprayed onto different substrates. 

Waterborne polyurethane adhesives have the characteristics of low volatile organic compound content, low or no environmental pollution, and non-combustibility. They are the key development direction of polyurethane adhesives.

8. Cables and wires

High and low temperature resistance is the key to cable performance, so TPU is used as a coating material for high-grade cables. Ultra-high hardness, low temperature flexibility, abrasion resistance, environmental resistance and weather resistance, these excellent mechanical and physical properties extend the durability and service life of cables. The protective sheaths of cables, optical cables, seismic cables and aircraft cables for special terrains are generally made of TPU material. Since its resistivity is greater than 1012Ω·cm, it has the advantages of wear resistance, hydrolysis resistance, weather resistance, flexural resistance, and high hardness. . TPU material has good insulation and good protection for wires, which is safe to use and is not easy to cause fire accidents. 

9. The application of TPU in the textile industry

In industry, the melt spinning of spandex is mainly used. The excellent performance of spandex: outstanding high resilience, the high resilience of spandex is unmatched by all elastic fibers at present, its elongation at break is greater than 400%, up to 800%, even at 300% tensile deformation , the rebound recovery rate is still more than 95%; excellent tensile strength and tear strength; strong weather resistance and ultraviolet radiation resistance; chemical resistance, washing resistance; good affinity with dyes. Spandex has been widely used in textiles and is a new type of textile material with high added value. Spandex is generally not used alone, but is incorporated into the fabric in a small amount. Such as stockings, swimwear, dance clothes, Lycra (pure cotton covered spandex yarn), clothing, etc., in traditional textiles, only adding less than 10% of spandex can greatly improve the quality of traditional fabrics, showing that Soft, comfortable, beautiful and elegant style. 

For example, Lycra fabrics that have been popular in the fashion circle in recent years. Lycra is a trade name of INVISTA, the world's largest integrated fiber and polymer company. INVISTA occupies a market monopoly in the spandex field. Lycra is almost synonymous with all spandex yarns. It completely replaces the traditional elastic elastic thread, and Lycra has almost become an indispensable element in the special requirements of gym clothes and swimwear. It allows people to show their curves and stretch their limbs freely without pressure. Lycra is not only versatile in everyday clothing, it is also a pet in the popular kaleidoscope fashion designers make. Lycra has therefore been called the magic fiber by ecstatic people. When the designer talks about his work, he likes to say that he uses a little Lycra. Perhaps, not only is the clothes using Lycra quite fashionable, the word itself has a strong fashion color.

As people put forward new requirements for fabrics, such as light weight, comfortable fit, soft texture, etc., the proportion of low-denier spandex fabrics in synthetic fabrics is also increasing. It is also useful to use spandex naked yarn and twisted yarn made of spandex and other fibers combined and twisted, mainly used for various warp knitting, weft knitting fabrics, woven fabrics and elastic fabrics.

10. Application of TPU in aerospace industry

The barrier net made of TPU as raw material in my country by extrusion method has excellent characteristics such as high strength, light weight, good elasticity, not easy to mold, tear resistance, low temperature resistance, and good oil resistance. The mesh body made of fluorescent substances added to TPU can emit light at night. Its various properties are superior to the net body woven with nylon in the world. For example, the woven vertical belt of nylon has a tensile strength of 139.2 MPa, and the tensile strength of the vertical belt made of TPU reaches 186.3 MPa. Therefore, the TPU net is more effective as a blocking net. The aircraft thin-walled fuel tank made of TPU has simple process, thin wall, light weight, and long life. TPU has high radiation resistance and is suitable for making protective clothing for space flight personnel X-ray and atomic energy workers. With the continuous development of the aviation industry, the demand for aircraft maintenance technology has also increased accordingly, and the requirements will become more and more strict. The excellent performance of TPU materials will make it more valuable.

11. Application of TPU in other industries

TPU materials are widely used in refrigerator manufacturing, transportation, civil construction, electromechanical, petrochemical, mining machinery and other industries. It has the characteristics of high strength, good toughness, wear resistance, cold resistance, oil resistance, water resistance, aging resistance, and weather resistance that other plastic materials cannot match. Many unique functions such as warmth retention, UV resistance and energy release can be made into various parts and machine outer protective shells. TPU can also replace any other PU plastic box PVC plastic.

Andaluz Acessibilidade from São Paulo, Brazil, has teamed up with Bayer MaterialScience to develop a personal guidance system for the ground. This kind of system is not only very easy to lay, but also has a tactile feedback function, which can play a more ideal guiding role for pedestrians. The system consists of signs or tiles affixed to the ground, which, although only a few millimeters thick, still provide haptic feedback when people walk on the ground. These haptic elements are made of thermoplastic polyurethane (TPU) material developed by Bayer MaterialScience. Compared with other similar materials, this material has many advantages. For example, if concrete markers are used, a smaller area must be removed from the ground and the appropriate elements inserted into it. Afterwards, in order to achieve the required guiding requirements, these elements must be sprayed and coated with a colored adhesive film. Therefore, the laying process of such a system is more time-consuming. Bolts and panels made of rubber are not only far inferior to TPU markings in terms of wear resistance, but because of their thickness, they must be cut to embed into the ground.

The Lenovo TS540 server uses TPU material for shock absorption. The innovative holographic buffer technology of the Think Server family, which perfectly combines the impact resistance of zinc-magnesium alloy widely used in auto parts and the shock absorption of TPU, can cover various frequency bands of high, medium and low; Vertical shock absorption, effectively absorb vibration.

3. The future direction

Due to the rapid development of shoe materials, machinery, pipes, automobiles, construction and other industries, and more and more wear-resistant materials use TPU, the global demand for TPU is increasing, with a compound annual growth rate of 6.6%. A report shows that by 2015, the global TPU market demand will maintain an annual growth rate of 5.6%. With the gradual reduction of the unit price of TPU particles and TPU films and the restrictions on PVC and other materials in the EU, the cost performance of TPU materials has gradually emerged. At the same time, the excellent performance and environmental protection characteristics of TPU are also increasingly welcomed by consumers. The demand for materials will reach about 750,000 tons.

The development of the TPU industry is relatively unbalanced on a global scale. In developed countries in Europe and the United States, the TPU industry is relatively mature. In my country and Southeast Asia, due to industrial transfer, the rapid development of sports shoes, automobiles, machinery, clothing and other industries in these regions has gradually become a The world's processing plants, the TPU industry has developed rapidly. Among them, Asia is the world's largest TPU market, accounting for about 60% of the world's demand, and Europe, the Middle East and Africa accounted for 24% of the TPU demand. In terms of demand areas, by 2012, the footwear industry was the largest end-use area of ​​TPU, accounting for 38% of the total market, with a consumption of 133,015 tons, closely followed by engineered products (28%), with approximately 111,730 Ton. In third place is automobiles, which account for 11% of the total market. Since the 21st century, my country's TPU materials have a huge application market in the fields of shoe materials, rubber rollers, rollers, pipes, adhesives, synthetic leather, melt-spun spandex, and films. In 2012, the domestic market consumed 249,000 tons, mainly low-end products, and high-end products used in the fields of adhesives, melt-spun spandex, films, etc. At present, the quality of domestic products is still poor and unstable, and the scale is small. Imported from the United States. The overall situation of TPU is that imports from Europe and the United States, Taiwan and South Korea produce products in mainland factories and China produces three-thirds of the world, but China is in a weak position. Most foreign companies are diversified product manufacturers, and the products involve multiple links in the polyurethane industry chain. BASF provides TPU upstream raw materials such as MDI, polyols and other basic chemical materials, and also produces TPU particles and TPU film products based on TPU particles. For example: Bayer MaterialScience's TPU film is mainly produced by its North American materials company Dureflex series products, Bayer Materials also produces other polyurethane products. Huntsman's TPU film products mainly focus on TPU glass sheets, and Huntsman also provides basic chemical products such as MDI. Lubrizol manufactures a wide variety of TPU particle and TPU film products. Therefore, foreign companies have many types of products, and TPU film is one of a variety of material products, and the product structure is relatively comprehensive. The product structure of Taiwanese companies is mostly TPU film and other plastic products that constitute the company's main products. The products of enterprises in Taiwan are mainly concentrated in the markets of pneumatic tubes, shoe materials, and adhesives. In addition to the production of TPU film, Taiwan Dingji Chemical also produces TPU seals, pneumatic tubes, conveyor belts and other related TPU products. Taiwan Coating Chemical produces TPU particles and extends the TPU particle production line to TPU film. Due to the late start of Chinese TPU enterprises, few foreign-funded enterprises can break through the raw material technology monopoly. At present, only a few enterprises such as Yantai Wanhua can independently produce MDI and other raw materials, and most of them can only rely on imports, resulting in the entire industry relying heavily on imports. Moreover, domestic enterprises are also in commercial competition with foreign-funded enterprises, and advanced technology must be monopolized. Therefore, China's TPU enterprises are mainly aimed at the low-end TPU film market in China. At the same time, the technical and production experience thresholds for TPU film production are relatively high, so at this stage, the number of professional TPU film manufacturers in China is relatively small and the industry concentration is high. China's TPU film manufacturers have the highest degree of specialization. The obvious feature is that they produce many types of TPU films, covering a wide range of TPU film markets.

Due to the excess of low-end products (including by-products) in the domestic TPU market, prices continued to decrease and industry profits declined. However, the market of high-end TPU products of film grade, melt-spun spandex fiber grade, high-quality extrusion grade and calendering grade is currently basically controlled by imported products. Domestic enterprises should actively develop high-end products suitable for the domestic market. dominant position. 

With the enhancement of TPU material properties, the sports equipment and footwear industries are more and more inclined to TPU products, especially UV-resistant and transparent materials. TPU materials are very suitable for the Chinese market where sports goods and sports shoes are in high demand, and may also be used in the electronics industry in the future. Therefore, in the future, the application direction of TPU will improve the direction of TPU performance, and further expand the scope of application of TPU, mainly including biomedical equipment, industrial parts, sports shoes and other applications. Therefore, the main goal of China's TPU is to increase scientific research and development efforts, improve the level of process technology, improve the R&D and manufacturing rate of TPU products with various performances, and expand the high-end market share.