Polyurethane oil seal

Polyurethane oil seal 1. The concept of polyurethane oil seal. Polyurethane oil seal is a seal made of polyurethane oil seal material. Sealing refers to the fact that at least a pair of end faces perpendicular to the axis of rotation are kept close to each other under the action of fluid pressure and the elastic force (or magnetic force) of the compensation mechanism and the auxiliary seal to prevent fluid leakage. installation. 2. Polyurethane oil seal material Polyurethane material is currently the best imported mechanical seal thermal insulation material in the world. The main chain contains -NHCOO- repeating structural unit of a type of polymer. The English abbreviation PU. It is formed by polymerization of isocyanate (monomer) and hydroxyl compound. Due to the strong polar urethane group, it is insoluble in non-polar groups and has good oil resistance, toughness, abrasion resistance, aging resistance and adhesion. Different raw materials can be used to produce materials suitable for a wide temperature range (-50～150℃), including cartridge mechanical seal elastomers, thermoplastic resins and thermosetting resins. It is not resistant to hydrolysis at high temperature, nor is it resistant to alkaline media. Commonly used monomers such as toluene diisocyanate, diisocyanate diphenylmethane and so on. Polyols are divided into 3 categories: simple polyols (ethylene glycol, glycerol, etc.); polyester oligomers containing terminal hydroxyl groups, used to prepare polyester polyurethane; polyether oligomers containing terminal hydroxyl groups, used Preparation of polyether polyurethane. The polymerization method varies with the nature of the material. When synthesizing elastomers, first prepare low molecular weight diols, and then react with excess aromatic isocyanates to form isocyanate-terminated prepolymers, and then chain extension with butanediol to obtain thermoplastic elastomers; if aromatic diamines are used The chain is extended and further cross-linked to obtain a cast elastomer. The prepolymer is chain-extended with hydrazine or diamine to obtain elastic fibers; the prepolymer with a large excess of isocyanate is mixed with catalyst and blowing agent to directly obtain rigid foam. If monomer, polyether, water, catalyst, etc. are mixed, the flexible foam can be obtained in one step reaction. Monomers and polyols react in solution to obtain coatings; adhesives use polyisocyanate monomers and low-molecular-weight polyesters or polyethers to mix and react during use. 3. The role of polyurethane oil seals. Polyurethane elastomers are used as rollers, conveyor belts, hoses, auto parts, shoe soles, synthetic leather, wires and cables, and medical artificial organs, etc.; soft foams are used as pads for vehicles, rooms, and clothing. Rigid foam is used for heat insulation, sound absorption, packaging, insulation, and low-foaming synthetic wood. Coatings are used for high-end vehicles, furniture, wood and metal protection, pools, dams and construction anti-leakage materials, and fabric coatings. Adhesives have good adhesion to metals, glass, ceramics, leather, fibers, etc. In addition, polyurethane can also be made into emulsions and magnetic materials. 4. The composition of mechanical seals: There are mainly the following four types of components: a. Main seals: moving and static rings; b. Auxiliary seals: sealing rings; c. Compression parts: springs, push rings; d. Transmission parts ：Bounce skip seat and key or fixed screw. Keywords: Grundfos mechanical seal, imported mechanical seal, cartridge mechanical seal