Status And Prospect Of TPU Film For Shoe Material Chemical Industry

　　 TPU thin films It is an important application form of TPU materials. In recent years, with the development and progress of high technology, it has been applied more and more widely. However, because of its difficulty in processing and unstable products, no manufacturers in mainland China have been able to make mass production.

　 Production and application status of 1 TPU thin films

Production analysis of 1.1 TPU film

The production of TPU materials is mainly distributed in the United States, Western Europe and Japan, and China's Taiwan area also has a certain proportion. Internationally, there are representatives of Bayer, Dow, Mobay, Dupont and so on. Among them, there are also more influential TPU producers in Taiwan, such as three sway chemical industry, Gao Ding chemical industry, Sun Sheng chemical industry, DingZing chemistry and so on. TPU thin film is an important application of TPU, and is also one of the most potential markets for TPU. Its main manufacturers include German Bayer, DingZing chemistry in Taiwan, and Jinxing Chemical in Korea. Among them, DingZing company is especially outstanding in the industry.

However, on the one hand, TPU film products have very unstable characteristics in the production process. Development and testing require advanced technology and equipment. On the other hand, due to the competition of other materials, the economic factors also make the production of TPU thin films more efficient, and can produce high-quality TPU films to reduce the cost. At the same time, the TPU film is required to be more extensive, the thickness can be thinner and thicker, and better technology can be introduced to enhance its physical properties, thereby obtaining higher added value. The above two aspects have become the bottleneck restricting the development of TPU manufacturers in China.

1.2 application status of TPU thin films

Because TPU has the characteristics of high strength, wear resistance, good elasticity and weather resistance, TPU film is widely used in the automotive industry. Shoe material Clothing, clothing, chemical industry, electronics, medical and other fields. Since many countries are paying more and more attention to environmental protection, especially since the European Union prohibits the use of PVC materials such as shoe materials, people are trying to find other suitable materials to replace them.

Because TPU is environmentally friendly, non-toxic, easy to recycle and decompose, TPU film has become the best substitute for PVC material on shoe material, and the place where PVC can be used can be replaced by TPU. As a pass to enter the European and American markets, the inspection reports of internationally renowned testing organizations such as SGS, ASTM, JIS and FDA are also very important.

For example, the famous film brand DingZing Film has already passed these certifications. Its film quality is stable, non-toxic, pollution-free and contains eight heavy metals, which can be incinerated and decomposed. This makes the brand widely recognized in the world.

TPU film is divided into two categories: polyester and polyether, among which polyester products have good heat resistance and chemical resistance, and are widely used in replacing PVC products. Polyether has better resistance to low temperature, water resistance and mildew resistance, and is widely used in products related to water.

　 The application fields of TPU films are generally summarized as follows:

(1) the introduction of high technology water affinity to waterproof and moisture permeable TPU films on textiles makes TPU film more excellent in water permeability besides high water repellency. The breakthrough of this material, combined with the technology of textile laminating, has greatly improved the added value of textiles. It is representative of DingZing's Dintex brand and Germany's Goretex brand. It is popular with consumers as a new and practical cloth.

(2) non yellowing series TPU films for UV protection.

(3) hot melt adhesive film TPU film for adhesion.

(4) the TPU film used for shoe material has good printability and workability, making TPU a special shoe material film for sports shoes, casual shoes and sandals. For example, internationally renowned sports shoes such as Nike, Reebok, Converse, Adidas and other well-known brands in China such as Anta, Lining, XTEP, Hongxing Erke are all loyal users of TPU films. In addition, TPU film is also the best choice for some three-dimensional trademarks.

(5) the TPU film on blowing products is worth pointing out, because the ratio of raw materials and the temperature of the reaction are not easy to control when the TPU is synthesized, and the instability of the TPU leads to its thickness not well controlled. Therefore, the producers usually do not use the area of the film as a yardstick of sale. The actual sale is often based on kilograms as a yardstick of sales. Only in this way can the value of material be truly reflected. And companies that need to use thin films often only consider how long and wide materials are. Therefore, the length (code) and weight (kg) of TPU film often need to be converted. The market price of TPU film is about RMB70 yuan /kg, and its price varies correspondingly with the increase or decrease of oil and its synthetic raw materials.

Study of 2 TPU thin films

2.1 raw materials for TPU films

The process is to heat three kinds of raw materials in their respective tanks. The temperature is 90, 70, 40, respectively, and the metering pump is applied to the mixing head. The rotating rotor is mixed evenly, and is injected onto the conveyor belt. The TPU liquid has been solidified into sheet metal through the drying channel, and the pieces are broken or cut into pieces, and sent to the extruder for two times at 132 degrees.

2.2 processing research

The development of TPU thin films is closely related to the processing methods of TPU materials. At the same time, some new requirements for the properties of raw materials are also proposed. Because domestic TPU grain is difficult to meet the processing requirements, even if domestic manufacturers can produce, most of them are imported TPU pellets from abroad.

The main processing methods of TPU thin films are blow molding, tape casting, T extrusion and calendering. The final product usually does not need vulcanization crosslinking reaction, which can shorten the production cycle and recycle waste materials. TPU films can be widely used as auxiliaries and fillers to improve some physical properties, processability, or reduce costs.

Points for attention in processing:

Ensure that the material is kept within 4 h in the dryer, because TPU is easy to absorb moisture.

The viscosity of material is very sensitive to temperature and its change. Attention should be paid to controlling the temperature of reaction and local temperature control of die.

In terms of thickness, the mass distribution of thin film produced by mass production is rather poor. Therefore, the thickness of TPU film should be accurately measured in the production process according to the processing method used, so as to achieve better control of film thickness.

(4) the structural design of the mold ensures the smooth passage of materials and does not allow the retention of materials.

Due to the characteristics of TPU materials, the transmission power of processing equipment is 1.5 to 2 times larger than that of some general plastics.

Blown film is a relatively new technology with little production. Before processing, the material should be dried. The TPU drying temperature range is 82~121 degrees.

Strictly speaking, TPU film can not contain plasticizer (plas - ticizer), because plasticizer itself is a toxic chemical substance. However, due to technical and equipment reasons, many companies have to use it to reduce the viscosity of particles, reduce the hardness and reduce the molecular weight to achieve the purpose of easy processing. The disadvantage is that the TPU film will produce embrittlement, odor and migration problems, thus seriously affecting the physical properties and environmental protection of the films.

At present, the thinnest thickness of the TPU film in the world is 10 um, and Japan's Mirac -tranTPU can reach dozens of um, while the DingZing TPU film can achieve 12 um, which is superior to the TPU film producers of Korea, Japan and the United States. TPU film products are very suitable for hot pressing, high frequency machining, sewing or bonding agents, and also suitable for printing ink, vacuum or high frequency to suppress stereoscopic effect.

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　　 Study on the properties of 2.3 TPU thin films

The properties of TPU thin films are mainly studied in terms of tear properties, wear resistance, flexural resistance, water resistance, yellowing resistance, low temperature resistance, heat and oxidation resistance, mildew resistance, oil resistance, gas diffusion and biomedicine. Experiments show that compared with other conventional plastic materials, TPU film has superior performance in these aspects.

　 2.4 detection of TPU thin films

At present, the thickness error of TPU thin films produced by the world is still very large. In this case, if we want to win more market share, sophisticated production lines and good measurement and control technology are necessary. There are two purposes for the detection of TPU thin films. The first is to detect holes and waste products. The second is to control the thickness of TPU films by testing. The thickness distribution of the thin film is measured by a thickness gauge around the membrane bubble.

Some sensing elements and capacitive sensors are also entering the market for thin film measurement. At present, the detection of TPU thin films in the world is that there will be 7~10 small holes in a roll of TPU film on most manufacturers. Only a small number of manufacturers can achieve only 1~2 volumes, sometimes even small holes.

Because of the poor proportion of raw materials and reaction temperature of TPU film, many customers complain and complain about the error of TPU film products. The field experience is: even on the same day, the same machine produces the same specification products sometimes there are great differences. Therefore, for the TPU manufacturers who want to be strong and big, they should invest more in production technology and measuring equipment. Only in this way can we create quality products and customer satisfaction products. But advanced TPU film detection equipment is often very expensive, so for many small and medium TPU film manufacturers, controlling the thickness and scrap rate of the film is a headache.

For customers to purchase TPU thin films, the problem should be noticed is that when observing the surface effect of TPU films, it is not possible to cut a small piece to observe, and use a large volume as a sample, so as to observe some detailed effects and differences. At present, there is no water ripple, no particles, very flat TPU film is most suitable for making Logo on clothing and shoes. In order to protect TPU films and keep them clean, PE, PET or release paper are often used as protective films. So the actual TPU film is often two layers, and the protective film can be uncovered when used.

　 Prospects for 4 TPU films

TPU film is a green material because of its excellent properties.