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

据pvc行业人士称：乙烯法PVC和电石法PVC应用领域没有太大区别，只是生产工艺不同。电石法PVC主要用于管材、建材，而乙烯法PVC主要用于高档型材、透明片材、膜及汽车工业内装制品（如车顶内衬、地毯、车内蒙皮、绝缘管道、加油漏斗、车门饰条、波纹管、密封条、座椅、仪表板表皮等制品）乙烯法VCM 含杂质种类比电石法VCM 稍多一些，但行业公认为乙烯法聚氯乙烯在质量上优于电石法聚氯乙烯。

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.

乙烯法PVC和电石法PVC区别的原因

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

VCM中杂质对聚氯乙烯质量的影响

Impurities in VCM  effect the quality of PVC

电石法PVC所得VCM中的杂质显著降低电石法PVC树脂质量的热稳定性、白度及耐老化性，进而影响到PVC制品的色泽度等质量问题。

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.

材料本身性能方面的影响

The performance of the material’s affection

电石法PVC树脂的分子质量比乙烯法PVC树脂低，其分子质量分布比乙烯法PVC树脂宽。PVC料的加工及制品性能不仅取决于平均分子量的高低，也与PVC的分子量分布有密切关系。一般地说，分子量分布较窄的PVC树脂成型加工性能好，这不仅因为要保持加工性能和制品性能的均匀性，而且还因为双键等异常结构大多集中在低分子量级分。因电石法PVC分子量分布宽将显著降低其热稳定性、耐热变形温度、电气绝缘性、力学强度和耐老化性；另外还可使PVC树脂在通常的加工条件下不易塑化均匀，使制品存在严重的内在质量问题。

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.

PVC树脂加工水平的影响

Influence of PVC resin processing level

我国PVC树脂加工生产小作坊、 小企业比较多，生产加工技术水平比较低。研发方面投入力量非常少，在生产加工过程中不能及时解决电石法PVC树脂自身存在的缺陷，导致电石法PVC树脂制品档次不高，影响了电石法PVC树脂在高档次制品中的应用。

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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