TPU has advantages of good mechanical strength, wear resistance, oil resistance, low temperature resistance, high elasticity, etc. At same time, raw material is environmentally friendly and environmentally friendly, and has a wide range of applications. With development of social needs, traditional single TPU material can no longer meet needs of production and household, so it is necessary to modify TPU to improve its heat resistance, aging resistance, fire resistance, anti-static effect and other shortcomings.
TPU modification type
1. Brief introduction to TPU
TPU is a polymeric synthetic material that has both elasticity of rubber and plastic rigidity. It usually consists of a polyol compound, a diisocyanate, a chain extender and a small amount of additives. It consists of a soft segment and a hard segment as a result of a polyaddition reaction. Block polymers, consisting of segments. The structure, ratio, ability to form hydrogen bonds and crystallization properties of soft segment and hard segment in macromolecule determine elasticity, strength, elongation, water resistance, wear resistance, high and low temperature properties of TPU.
2. Mixed Alloy TPU
Modifying blending of TPU and other high polymer polymers can integrate performance advantages of each polymer component and compensate for performance defects and disadvantages of any individual component. The cost of TPU is relatively high, by mixing it with other materials, it can also reduce cost of raw materials and improve economic benefits without affecting overall performance. Commonly used resins mixed with TPU include POM, PA, PP, PVC, ABS, etc. TPU materials have advantages of high elasticity, high strength and high modulus, and are often used as stiffeners for other polymers in blending process.
Table 2-1 Type of TPU blend
3. Anti-static TPU modification
TPU is also a kind of plastic and has good electrical insulation. It is easy to generate static electricity during use. The accumulation of static electricity adversely affects processing and production of products. Therefore, in order to obtain products from TPU with antistatic properties, it is necessary to carry out an antistatic modification of TPU. Commonly used antistatic agents include DE-8A, carbon nanotubes, and conductive carbon black.
Fourth, flame retardant modification of TPU
TPU is highly flammable and has an oxygen limit of 18-20%. Once ignited, it releases toxic gas accompanied by a lot of smoke, severe melting and dripping occurs, which can easily lead to secondary combustion. ignition causing high losses.
At present, widely used additive flame retardants mainly include halogen flame retardants, phosphorus flame retardants, nitrogen flame retardants, intumescent flame retardants, synergistic flame retardants, etc. There are two main ways to improve fire resistance of TPU: synthesis of reactive flame retardants, which graft flame retardants to hard and soft segments of TPU molecular chain to obtain TPU with highest fire resistance; mixing method to uniformly mix flame retardant with TPU matrix to obtain TPU composite material with good flame retardant properties.
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