The first generation of Cheap POLYURETHANE SEALANT FOR GENERAL USE price china is one component, without curing agent, with high Mn. It relies on the activation temperature to bond the film. However, it has poor water resistance and heat resistance, poor leveling of the rubber layer, easy clogging of the wire roller, many white spots of the composite film, easy delamination, and easy deformation during heat sealing. The second generation is a two-component one, with a curing agent added on the basis of a single component. The resin Mn of this Cheap POLYURETHANE SEALANT FOR GENERAL USE price china is high, which can improve the water resistance, heat resistance and other properties, and the heat seal is not deformed and the composite film is not delaminated. Although its Mn is lower than that of the single component, the leveling property of the adhesive layer and the degree of blocking of the net wire are not completely solved at present, and the solvent needs to be added when applying.

The commonly used acetone production process is relatively mature and is a common method in the early stage of the development of Cheap POLYURETHANE SEALANT FOR GENERAL USE in China. However, the production process uses flammable and toxic solvents such as acetone to adjust the degree of reaction system, which is neither environmentally friendly nor economical; In the later stage of the reaction, although we try to evaporate it, there are more or less residual solvents that migrate to the contents of the package, which hinders food safety. The quality of the composite film is also poor, and it is generally only used for aluminum coating composite, which has been eliminated by European and American countries.

The prepolymer dispersion method can react with a chain extender slightly soluble in water during dispersion without or with little solvent to obtain a Cheap POLYURETHANE SEALANT FOR GENERAL USE price china with higher m and higher solid content. At the same time, after chain extension, a more polar pulse bond is formed in the molecular chain, which can improve the composite strength, water resistance and solvent resistance of the composite membrane. The key is to master the competitive reaction of isocyanate vinegar with water and amine in the process of dispersion and chain extension, so as to keep the batch stability of product performance. In recent years, domestic research units and composite film factories have begun to develop and apply POLYURETHANE SEALANT FOR GENERAL USE, and its apparent consumption is estimated to be 15000 T / A.

At present, the obstacles faced by POLYURETHANE SEALANT FOR GENERAL USE in China are: I) solvent is required in the production process, resulting in adverse consequences. The Cheap POLYURETHANE SEALANT FOR GENERAL USE price china is several times higher than that of the solvent type, which is difficult for the composite membrane factory to accept for the time being, and is only used for the export of composite membrane products. 2) The particles of POLYURETHANE SEALANT FOR GENERAL USE dispersion are not uniform and stable. The experimental data show that if the particle size of polyurethane sealant is less than 100 nm and the distribution is uniform, a stable dispersion can be obtained. The particle size also directly affects the operation capacity and speed of dry compounding equipment. The transparency of the fine particle polyurethane sealant is higher than that of the solvent type composite film. 3) The properties such as initial viscosity, coating property, composite property, dryness, energy consumption, water resistance, heat resistance and solvent resistance are secondary to the solvent type.