Polyurethane oil seal
Polyurethane material is a very good insulation material in the world. A class of polymers containing NHCOO repeat units in the main chain. English abbreviation PU. By the polymerization of isocyanate (monomer) and the base compound. Because of the strong polarity of the base of the acid ester, insoluble in non-polar groups, has good oil resistance, toughness, wear resistance, aging resistance and adhesion. The material can be prepared to adapt to a wide temperature range (50 to 150 DEG C) by different raw materials, which comprises an elastomer, a thermoplastic resin and a thermosetting resin. At high temperature, it is not resistant to hydrolysis and alkaline medium.
Commonly used monomers such as a diisocyanate, diisocyanate, such as two benzene, etc.. Polyols can be divided into 3 categories: simple Polyols (ethylene glycol, glycerol etc.); polyester oligomer containing end through the medium, used for the preparation of polyester polyurethane; with the end of the group polyether oligomer, used for the preparation of polyether polyurethane. The polymerization method varies with the nature of the material. Synthetic elastomer before preparation of low molecular weight diols, and aromatic isocyanate and excessive reaction, generate isocyanate terminated prepolymer, and butylene glycol chain extender, thermoplastic elastomer; if using two aromatic diamine chain extender and further crosslinked, get casting elastomer. The prepolymer is expanded with hydrazine or two amine amine to obtain the elastic fiber; and the prepolymer with a relatively large amount of isocyanate is mixed with a catalyst and a foaming agent to obtain the rigid foam plastics. For example, monomer, polyether, water, catalyst and so on can be obtained by one step reaction. The reaction of the monomer and the polyol in the solution can be obtained with the coating, and the adhesive is mixed and reacted with a polyisocyanate monomer and a low molecular weight polyester or polyether when used.
The polyurethane elastomer used for roller, conveyor belts, hoses, auto parts, shoe soles, synthetic leather, such as wire and cable; soft foam cushion for a vehicle, bedroom, clothing, rigid foam for insulation, sound-absorbing, packaging, insulation and low foaming composite wood, paint for advanced vehicle, furniture and wood and metal door, pond dam and building waterproofing materials and fabric coating etc.. Adhesive has good adhesion to metal, glass, ceramics, leather, fiber and so on. In addition, polyurethane can also be made into emulsion, magnetic materials, etc.
Two, polyurethane oil seal performance and use
The polyurethane oil seal is mainly used in hydraulic cylinder, easy to install and can scrape the dust adhered on the piston rod of the mian. Green polyurethane oil seal hardness is slightly lower, and the higher the hardness of blue and can withstand greater pressure. The polyurethane oil seal has good mechanical properties, abrasion resistance and oil resistance, suitable for the most demanding working conditions, good to prevent access to external impurities, so as to achieve excellent sealing performance, high pressure hydraulic cylinder is the most commonly used seal.
Categories include: UN, DH, UH, BS, B