TPU material from SIKO
TPU (thermoplastic polyurethane) is a kind of polyurethane that can be plasticized by heating and dissolved by solvent. Thermoplastic polyurethanes have little or no chemical cross linking in their chemical structures compared with mixed and castable polyurethanes. Their molecules are almost linear, but there is a certain amount of physical exchange.
What is the classification of TPU?
For example, according to the soft segment structure can be divided into polyester type, polyether type and butadiene type, they contain ester group, ether group or butadiene group respectively. According to the hard segment structure, it can be divided into ammonia ester type and ammonia ester urea type, which are obtained by diol chain extender or diamine chain extender respectively. The common division is divided into polyester type and polyether type.
It can be divided into pure thermoplastic and semi-thermoplastic with or without cross linking. The former is a pure linear structure without cross linked bonds. The latter contains a small amount of urea formate cross linked bonds. According to the use of finished products can be divided into special-shaped parts (various mechanical parts), pipe (sheath, bar profile) and film (thin, thin) as well as adhesives, coatings and fibers.
How is TPU SYNTHESIZED?
Although there are many categories of TPU, but from the molecular structure, is polyurethane. So how does it come together? According to the different synthesis process, it can be divided into bulk polymerization and solution polymerization.
In bulk polymerization, it can be divided into pre-polymerization and one-step polymerization according to whether there is pre-reaction. The pre-polymerization method is to react diisoc yanate and macromolecule diol for a certain time, and then add chain extension to produce TPU. TPU is synthesized by mixing macromolecules of diol, diiso-acid ester and chain extender in one step.
Solution polymerization is to dissolve diisocyanate in solvent first, then add macromolecule diol to make it react for a certain time, and finally add chain extender to generate TPU
Soft segment type, molecular weight, hard segment or soft segment content and TPU aggregation state affect the density of TPU, and the density is about 1.10 ~ 1.25, no significant difference from other rubber and plastics. The density of polyether TYPE TPU is lower than that of polyester type TPU at the same hardness.
The performance of the TPU
Like castable polyurethanes (liquid) and blended polyurethanes (solid), TPU has high modulus, high strength, high elongation and high elasticity, excellent wear resistance, oil resistance, low temperature resistance, and aging resistance. Among them, high tensile strength, high elongation and low permanent deformation rate under long-term compression are the significant advantages of TPU.
1, high tensile strength, large elongation
2. Resilience is very sensitive to temperature
3. The hardness range is Shaul A60~D80
Application areas of TPU
TPU is used for shoe material mainly because of its excellent elasticity and wear resistance. Footwear products containing TPU are much superior to ordinary footwear products in terms of comfort, so they are widely used in high-grade footwear products, especially some sports shoes and casual shoes.
2, the hose
Because of its softness, good tensile strength, impact strength and high and low temperature resistance, TPU hose is widely used as gas and oil hose for aircraft, tanks, automobiles, motorcycles, machine tools and other mechanical equipment in China.
TPU provides tear resistance, wear resistance and bending characteristics, high and low temperature resistance is the key to cable performance. Therefore, in the Chinese market, advanced cables such as control cables and power cables with TPU, used to protect the design of complex cable coating materials, the use is increasingly widespread.