TPU plastic raw material, that is, thermoplastic polyurethane. Thermoplastic TPU elastomer is made by extruding and mixing MDI containing NCO functional groups and POLYOL and 1.4BG containing OH functional groups.

Basic introduction

TPU: Chinese name is thermoplastic polyurethane. Due to its good elasticity, good physical properties, and excellent mechanical strength, it is widely used in processing methods such as injection, extrusion, calendering, and dissolving into solution-type resins. It is a plastic material frequently used by plastic processing industries, and its products cover the range of industrial applications and people's livelihood necessities.

In recent years, due to the continuous development of new products, the use of thermoplastic PU elastomers is continuing to increase, creating a new opportunity for low-cost, high-value-added industries for plastic processing industries.

It is increasingly popular because of its superior performance and environmental protection concept. At present, TPU can be a substitute for PVC wherever PVC is used. However, the advantages of TPU are far beyond the reach of PVC. TPU not only has excellent high tension, high tensile strength, toughness and aging resistance, but also is a mature environmentally friendly material.

Characteristics

Wear resistance

When the material is often subjected to mechanical effects such as friction, scraping, grinding, etc. during use, it will cause its surface to gradually wear, so the choice of material abrasion resistance is very important. TPU plastic raw materials have excellent wear resistance, more than five times that of natural rubber, and are one of the preferred materials for wear-resistant products.

Tensile properties

Tensile strength is as high as 70MPa, and elongation at break can be as high as 1000%.

Tear properties

The destruction of elastomers due to the expansion of cracks during application is called tearing, and tear strength is the ability of the material to resist tearing; generally speaking, TPU has a higher tear resistance, and its tear strength is very excellent compared with some commonly used rubber and plastics.

Flexibility

Many plastic materials are prone to breakage under repeated cyclic stress. TPU products can maintain excellent flexural resistance in different environments and are one of the best choices among polymer materials.

Hydrolysis resistance

TPU has good water resistance under turbid conditions and will not undergo significant hydrolysis within 1 to 2 years, especially the polyether series. The polyester series will completely decompose after being soaked in water at 50¡ãC for half a year, 70¡ãC for 3 weeks, or 100¡ãC for 3 to 4 days. This is one of the reasons why TPU is suitable as an environmentally friendly material. For products that need to be in frequent contact with water, it is recommended to use the polyether series.

High temperature and oxidation resistance

General plastic raw materials are easily oxidized in an environment above 70¡ãC for a long time, and TPU has good oxidation resistance; generally speaking, the temperature resistance of TPU can reach 120¡ãC.

Oil and chemical resistance

TPU is a highly polar polymer material with low affinity to non-polar mineral oils. It is almost not corroded by fuel oils (such as kerosene, gasoline) and mechanical oils (such as hydraulic oil, engine oil, lubricating oil, etc.); among them, polyester series products have better oil resistance among TPU products; the volume change of TPU film and sheet to grease is very small, and the tensile strength is even higher than the original initial value; it should be noted that if there is a small amount of water in the mineral oil, it will have different degrees of negative impact on the physical properties of the film.

Low temperature performance

TPU has very good low temperature resistance, usually up to -50¡æ, and can replace various fields where general PVC cannot be used due to low temperature embrittlement. It is particularly suitable for use in products related to cold zones.

Air tightness

TPU is very easy to weld using high frequency or hot pressing, so it is widely used in inflatable products. The gas coefficient refers to the rate at which a gas passes through a specified area of a sample at a certain temperature and pressure. The permeability of the same material to different gases sometimes varies greatly. Generally speaking, polyester series products have better air tightness than polyether series.

Biomedical performance

TPU has excellent biocompatibility, non-toxicity, no allergic reaction, no local irritation, and no pyrogen, so it is widely used in medical, health and other related products as well as sports and protective equipment.

Application range

TPU has been widely used in: footwear, clothing, inflatable toys, water and underwater sports equipment, medical equipment, fitness equipment, car seat materials, umbrellas, suitcases, bags, etc.

TPU film is widely used in sports shoes: trademark decoration on the soles and uppers, air bags, air cushions, oil bags, etc. Nowadays, there are two trends in the application of TPU film in sports shoes:

One is the popular trend caused by Nike sports shoes, that is, the TPU film is first screen-printed and colored, then formed by high frequency and bonded to the upper for decoration to achieve a special decorative effect.

The second is to use the waterproof and breathable TPU film and shoe cloth to achieve the effect of waterproof and breathable.

When TPU plastic raw materials are injected into the mold, pay attention to the following five reasons for the occurrence of various undesirable phenomena in injection molding: 1. The difference in the properties of the plastic raw materials themselves; 2. The improper setting of molding conditions such as temperature, pressure, and shooting speed; 3. The design or production of the molding mold is defective; 4. The shape and thickness of the molded product are poorly designed; 5. The improper selection of the injection molding machine and the insufficient capacity. In fact, the cause of poor injection molding is not simple. It is usually caused by the interweaving of the above factors. The judgment of the cause of the bad depends on the experience and technology of the operator. Mold filling process. It is recommended to consult relevant professionals before processing to reduce loss costs.

TPU American DuPont plastic raw material market application: From the shoes we wear to daily necessities, to electrical appliances, cars, aviation, satellites, etc., plastics are indispensable. With the development of urban construction and agricultural production factories, China's annual demand for single PC has reached about 260,000 tons. With the increasing demand for plastic raw materials for industrial and daily needs, multinational companies have invested in the construction of polycarbonate industry in China. At present, the multinational companies investing in PC production in China mainly include Bayer of Germany, Teijin of Japan, and GE of the United States. Among them, the project invested and constructed by Bayer of Germany and Shanghai Chlor-Alkali Co., Ltd. is expected to expand to 200,000 t/a.

Characteristics

The main characteristics of TPU are:

Wide hardness range: By changing the ratio of each reaction component of TPU, products with different hardness can be obtained, and as the hardness increases, the product still maintains good elasticity and wear resistance.

High mechanical strength: TPU products have outstanding bearing capacity, impact resistance and shock absorption performance.

Outstanding cold resistance: TPU has a relatively low glass transition temperature and still maintains good elasticity, flexibility and other physical properties at minus 35 degrees.

Good processing performance: TPU can be processed by common thermoplastic material processing methods, such as injection molding, extrusion, calendering, etc. At the same time, TPU and certain polymer materials can be processed together to obtain polymer alloys with complementary properties.

Oil-resistant, water-resistant, and mildew-resistant.

Good recyclability.

TPU, as an elastomer, is a material between rubber and plastic, which can be seen from its rigidity. The rigidity of TPU can be measured by the elastic modulus. The elastic modulus of rubber is usually 1~10Mpa, that of TPU is 10~1000Mpa, and that of plastic (nylon, ABS, PC, POM) is 1000~10000Mpa. TPU has a wide hardness range, from Shore A 60 to Shore D 80, and has high elasticity in the entire hardness range; TPU is flexible in a wide temperature range of -40~120¡æ without the need for plasticizers; TPU has good resistance to oils (mineral oils, animal and plant oils and lubricants) and many solvents; TPU also has good weather resistance and excellent resistance to high-energy rays. Well-known wear resistance, tear resistance, and flexural strength are excellent; high tensile strength, high elongation, and low long-term compression permanent deformation are all significant advantages of TPU.

The TPU properties introduced here include three aspects: mechanical properties, physical properties, and environmental properties.

1. Mechanical properties: The mechanical properties of TPU elastomers mainly include: hardness, tensile strength, compression performance, tear strength, resilience and wear resistance, flexural resistance, etc., and the mechanical properties of TPU elastic plastics, in addition to these properties, also include high shear strength and impact energy.

(a) Hardness: Hardness is an indicator of a material's ability to resist deformation, notches and scratches. TPU hardness is usually measured using Shore A and Shore D hardness testers, Shore A for relatively soft TPU and Shore D for harder TPU. Hardness is mainly determined by the hard segment content in the TPU structure. The higher the hard segment content, the higher the hardness of the TPU. As the hardness increases, other properties of TPU will also change, with increased tensile modulus and tear strength, increased rigidity and compressive stress (load capacity), decreased elongation, increased density and dynamic heat generation, and increased environmental resistance. TPU hardness has a certain relationship with temperature. When cooling from room temperature to the sudden change temperature (-4~-12¡æ), the hardness does not change significantly; at the sudden change temperature, the hardness of TPU suddenly increases and becomes very hard and loses elasticity, which is the result of the crystallization of the soft segment.

(b) The relationship between hardness and tensile stress and elongation, and the relationship between hardness and tear strength. As the hardness of TPU increases, the 100% modulus and 300% modulus increase rapidly, and the elongation decreases. This is because the increase in hardness is mainly due to the increase in hard segment content. The higher the hard segment content, the easier it is for the hard segment phase to form a secondary crystal or crystalline structure, which increases the number of physical crosslinks and limits material deformation. If the material is deformed, the stress must be increased, thereby increasing the modulus, while the elongation decreases. The relationship between the hardness of TPU and the tear strength is that the tear strength increases rapidly with the increase in hardness, and the reason is the same as the explanation of the modulus.

The formula and performance of TPU can be arranged and combined in a wide variety of ways. However, in the actual design of the formula and industrial production, the raw materials (polyols, polyisocyanates and chain extenders) are mutually restricted, making the research and development of high-end applications very difficult.

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