The Application field difference of PVC resin by calcium carbide method and ethylene method

According to the PVC industry, there is no big difference between the application fields of ethylene PVC and calcium carbide PVC, but the production process is different. Calcium carbide PVC is mainly used for pipes and building materials, while ethylene PVC is mainly used for high-grade profiles, transparent sheets, films and automotive interior decoration products (such as roof linings, carpets, car interior coverings, insulating pipes, refueling funnels, door trim strips, corrugated pipes, sealing strips, seats, instrument panel skins, etc.). Ethylene VCM contains slightly more impurities than calcium carbide VCM, However, it is recognized in the PVC industry that ethylene PVC is superior to calcium carbide PVC in quality.

There are following facts that can effect the calcium carbide PVC and ethylene PVC.

Impurities in VCM  effect the quality of PVC

Impurities in VCM from calcium carbide PVC significantly reduce the thermal stability, whiteness and aging resistance of PVC resin quality by calcium carbide method, thus affecting the color and luster of PVC products.

The performance of the materials affection

The molecular weight of calcium carbide PVC resin is lower than that of ethylene PVC resin, and its molecular weight distribution is wider than that of ethylene PVC resin. The processing of PVC materials and the properties of products depend not only on the average molecular weight, but also on the molecular weight distribution of PVC. Generally speaking, PVC resins with narrow molecular weight distribution have good molding and processing properties, not only because of the need to maintain the uniformity of processing properties and product properties, but also because abnormal structures such as double bonds are mostly concentrated in low molecular weight fractions. Due to the wide molecular weight distribution of PVC produced by calcium carbide process, its thermal stability, thermal deformation temperature, electrical insulation, mechanical strength and aging resistance will be significantly reduced; In addition, it can also make PVC resin difficult to plasticize uniformly under normal processing conditions, which causes serious internal quality problems of products.

Influence of PVC resin processing level

There are many small workshops and enterprises for PVC resin processing and production in China, and the level of production and processing technology is relatively low. The investment in research and development is very small, and the defects of calcium carbide PVC resin can not be solved in time during the production and processing process, which leads to the low grade of calcium carbide PVC resin products and affects the application of calcium carbide PVC resin in high-grade products.

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