The polyurethane material is the best international performance insulation materials. Main chain NHCOO-repeated structural unit of a class of polymers. Abbreviation. Polymerization of the isocyanate (monomer) and the polyol. Containing strong polar urethane groups, not soluble in non-polar groups, with good oil resistance, toughness, abrasion resistance, aging resistance and adhesion. Different materials can be prepared to adapt to a wide temperature range (-50 to 150 ° C) materials, including elastomers, thermoplastic resins and thermosetting resins. Impatience under high temperature hydrolysis, nor alkali medium.
Common monomers such as toluene diisocyanate, diisocyanates such as diphenylmethane. The polyol is divided into three categories: simple polyols (ethylene glycol, glycerol, etc.); polyester oligomers containing terminal hydroxyl, used for the preparation of the polyester polyurethane; polyether oligomers with terminal hydroxyl used Preparation of polyether-based polyurethane. Polymerization methods with different material properties. First synthetic elastomer preparation of low molecular weight diols, the reaction with excess aromatic isocyanate, isocyanate end groups of the prepolymer, chain extension with butanediol obtained thermoplastic elastomer; if using aromatic diamine chain extenders and crosslinking, casting elastomer. Prepolymers with hydrazine or diamine chain extender, elastic fibers; excessive more isocyanate prepolymer and a catalyst foaming agent mixed directly from the rigid foam. Such as monomer, polyether, water, catalyst, mixing, step response can be obtained by the soft foam. Monomer and polyols in the reaction solution, available coatings; adhesive while the isocyanate monomer and low molecular weight polyester or polyether mixed use and response.
The polyurethane elastomer is used as rollers, conveyor belts, hoses, automotive parts, shoe soles, synthetic leather, wire and cable and medical artificial organs, etc.; soft foam for the liner of the vehicle, room, clothing, hard foam is used as heat insulation, sound absorption, packaging, insulation, and low-foam synthetic wood, coatings for advanced vehicles, furniture, wood and metal protection, pond dams and construction of impermeable liner material, and fabric coating. Adhesives have good adhesion on metal, glass, ceramics, leather, fiber and other. In addition, the polyurethane can also be made of latex, and magnetic materials.
Polyurethane oil seals seals made of this material. Sealing means to keep the paste to merge the relative sliding constitute from at least one rotation axis perpendicular to face in the role of fluid pressure and the compensation mechanism of elastic (or magnetic) and auxiliary sealed with a device to prevent fluid leakage.