According to the general principle of molding process selection, realize the microphase separation of поліуретан elastomer and meet the requirements of excellent product performance. With reference to factors such as extrudability, moldability, ductility and spinnability, the molding process shall be performed according to the following principles : Поліуретан compound rubber, поліуретан cast rubber, поліуретан water emulsion and поліуретан thermoplastic four basic rubber types, respectively according to rubber, casting, coating and plastic molding processing methods; through the combination of classic molding processing methods, select the series of derived rubbers Molding processing method. Analysis of the dependence of the selection of поліуретан elastomer molding processing on deformation factors and curing factors shows that extrusion molding, injection molding and calendering are the key methods in molding processing.
1. Molding and processing method of поліуретан compound
Поліуретан compound rubber, as rubber, has high elasticity, high molecular weight and needs to be cross-linked. Therefore, the molding process is compounding, raw rubber plasticizing, rubber mixing, molding and vulcanization. The поліуретан elastomer can be molded by compression molding, extrusion molding, injection molding and calendering. The molding process is usually carried out at low temperature, which is conducive to morphological microphase separation. The vulcanization system of peroxides such as dicumyl peroxide and tert-butyl cumene can extend the time and carry out at low temperature, so that the permanent deformation of the поліуретан сполука мала, деформація стиснення невелика, а термостійкість покращена. Звичайно, вибір лиття під тиском може покращити точність розмірів виробу, а вибір пресування під тиском може поліпшити безперервність виробництва.
2. Формування та спосіб обробкиполіуретанклей для лиття
Поліуретанклей для лиття can be used as a complex product for pouring and infusion molding. The method is simple. As long as the liquid is injected into the mold, it can be cured into a product with a complex shape after heating. The one-step synthesis of поліуретанклей для лиття is to put polymer diol, diisocyanate and chain extender together, pour it into a mold and heat it to cure after being fully mixed, and perform post-vulcanization after the size is stable. Поліуретанклей для лиття is synthesized by prepolymerization method. The prepolymer and chain extender are put together and fully mixed. After vacuum degassing, it is injected into the mold to heat up and cure, and then vulcanized to obtain the product, and high-efficiency mold release agent is added for demolding. Reaction injection molding is essentially a one-step reaction or semi-prepolymerization reaction, but the reaction is carried out under high pressure and full mixing, which greatly improves the strength and adhesion properties of the product.
3. Поліуретанметод обробки водоемульсійного формування
Поліуретан water emulsion is environmentally friendly, but has poor film-forming properties. It needs to be cross-linked appropriately and can be molded by spraying.
4. Поліуретан thermoplastic molding processing method
Поліуретан thermoplastic is a kind of linear polymer, which can be used for reversible molding processes such as extrusion, injection molding, blow molding, calendering, and spinning. Semi-prepolymerization can effectively microphase separation. The calendering temperature is adjusted moderately, so that there is a balance between melt viscosity, fluidity and melt strength. In order to increase the hardness of поліуретан thermoplastics, micro-crosslinking is usually required to improve the mechanical properties of polymer materials, especially solid materials, on the basis of extrudability, moldability and ductility.
