Polyurethane thermoplastic elastomers can be classified into two types: polyester and polyether, with white irregular spherical or columnar particles and a relative density of 1.10-1.25. The polyether type has a lower relative density than the polyester type. The glass transition temperature of polyether type is 100.6-106.1 ℃, and that of polyester type is 108.9-122.8 ℃. The brittleness temperature of polyether type and polyester type is lower than -62 ℃, while the low temperature resistance of hard ether type is better than that of polyester type.
The outstanding characteristics of polyurethane thermoplastic elastomer are excellent wear resistance, excellent ozone resistance, high hardness, high strength, good elasticity, low temperature resistance, good oil resistance, chemical resistance and environmental resistance. Polyether can be used in humid environments. The hydrolytic stability of type ester is much higher than that of polyester type.
TPU (thermoplastic polyurethane elastomer) is an emerging plastic variety. Because TPU has good processability, weather resistance, and environmental protection, it is widely used in shoe materials, pipes, films, rollers, cables and wires and other related industries. Polyurethane thermoplastic elastomer, also known as thermoplastic polyurethane rubber, referred to as TPU, is an (AB) n-type block linear polymer. A is a polyester or polyether with a high molecular weight (1000-6000), and B is a linear polymer containing 2-12 For diols with chain carbon atoms, the chemical structure between AB chain segments is connected by diisocyanate, usually MDI. The general structural formula is shown in the figure. Thermoplastic polyurethane rubber is cross-linked by hydrogen bonds between molecules or light cross-linking between macromolecular chains. As the temperature increases or decreases, these two cross-linked structures are reversible. In the molten state or solution state, the intermolecular forces weaken, but after cooling or the solvent evaporates, strong intermolecular forces connect them together, restoring the original solid properties.
Polyurethane thermoplastic elastomer is non-toxic, odorless, soluble in solvents such as cyclohexanone, tetrahydrofuran, dioxane, and dimethylformamide. It can also be dissolved in toluene, ethyl acetate, methyl ethyl ketone, and acetone in appropriate amounts. In the mixed solvent composed of the proportion, it appears colorless and transparent, and has good storage stability.
PU polyurethane is a general name for polymer compounds generated by the reaction of diisocyanate or polyisocyanate with compounds with more than two hydroxyl groups. Its main chain contains many repeating NHCOO groups. Commonly used diisocyanates include toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), dicyclohexylmethane diisocyanate (HMDI), and polyethylene diisocyanate. Methyl polyphenyl polyisocyanate (PAPI), xylylene diisocyanate (XDI), etc. According to the different hydroxyl components used, it can be divided into two types: polyester type and polyether type. It can be used to manufacture plastic products, wear-resistant synthetic rubber products, synthetic fibers, hard and soft foam plastic products, adhesives and coatings, etc.
The properties of rubber materials made from different formulas are also different. These properties refer to mechanical properties and physical properties.
TPU and PU are essentially made of the same material. But when making these two kinds of rubber materials. The formulas they use are not the same. These two types of rubber materials are divided into many types of properties.