The key technologies to improve the performance of CPVC
February 14, 2019
Chlorinated polyvinyl chloride (CPVC) plastics are widely used in the production of various extruded products, including pipes, plates, profiles, sheets, etc. Some of the application fields of these products are chemical industry (corrosion resistance), places where fire protection is required, and places where high temperature resistance is required. The performance requirements for plastic products are relatively high. Common CPVC resins cannot meet the requirements and high performance CPVC is required. product.
However, in the chlorination process of CPVC resin, due to the difference in the PVC resin and the difference in chlorination conditions, the molecular structure of the CPVC resin may be different, especially in the chlorination process, such as breaks, branching, and cross-linking. The final performance of CPVC resin has a great influence on the molding process performance of CPVC products, so the performance and machinability of CPVC resin produced by different manufacturers are quite different.
To produce a CPVC resin with good properties, first of all pay attention to the choice of PVC resin. The PVC resin produced by the suspension polymerization method must be selected. It is also required to have a loose structure and a thin skin to facilitate the diffusion of chlorine gas in the PVC. It should be noted that the selected PVC resin must have a suitable relative molecular mass in order to control its flow parameters. .
Secondly, the chlorination pretreatment should be applied to the selected PVC resin. Since there is no special PVC resin for producing CPVC resin in the country, the PVC resin must be processed. This can increase the surface area of the PVC particles, increase the contact area with the chlorine molecules, and make the skin of the PVC resin thinner. The chlorine molecules can penetrate into the interior of the PVC resin and reduce the chlorine content on the surface of the CPVC resin, thereby achieving the purpose of reducing the melt viscosity and improving the processing performance. However, the method of adding a swelling agent should not be used in the treatment, otherwise it will bring about the difficulty of removing the swelling agent. In addition, the chlorination of PVC is an exothermic reaction. During the reaction, it is necessary to control the reaction temperature and the chlorine pressure by changing the amount of ultraviolet radiation.
In addition, when the CPVC resin is post-treated, sulphur dioxide gas may be added to the CPVC suspension water, followed by alkali neutralization and water washing and drying to improve the thermal stability of the CPVC resin. In production, depending on the molding process conditions, the addition of fillers or additives that are conducive to processing by physical methods can make the product performance of CPVC more excellent.
With many year's production experience, Novista develop and improve advanced water suspension chlorination technology to produce CPVC resin. Under this processing, the CPVC resin has excellent property of heat resistance and processing performance.
