Discussion on the quality of calcium carbide-process resins and ethylene-process resins

On this topic, Xue Zhihua from Jinxi Chemical Plant delivered a dedicated presentation at the 2007 PVC Technology Annual Conference organized by the Chlor-Alkali Industry Association.

President Xue’s insights at this year’s PVC conference sparked widespread discussion, especially the last two sentences of his summary! Almost laughed my head off: lol

At this annual conference, an expert claimed that the quality of PVC has nothing to do with the quality of the VCM monomer; there was no other content in the paper, yet it still won the second prize. That’s absolutely absurd. It seems that this expert’s organization could eliminate processes such as alkali washing and distillation in VCM production facilities – it’s utterly ridiculous

Calcium carbide-based resins and ethylene-based resins differ in quality, and the key factor is the difference in the quality of the monomers used. Ethylene-based monomers contain fewer impurities, which results in higher-quality resins; as a result, their price is also relatively higher. Of course, if the polymerization process and additives differ, the quality of the resin produced from monomers of the same quality will also vary.

Floors 1, 2, 3, and 4: Could you upload the paper you mentioned so we can discuss it together? This post was last edited by edc1233 on 2007-12-20 20:45.]

The cost of the ethylene method is much higher than that of the calcium carbide method; given that the price of the products produced is high, I don’t think it’s particularly necessary.

Strictly speaking, if the technological methods are perfect. Regardless of the raw material route, as long as 100% purity is achieved, the raw materials are not a factor affecting the quality of the resin. However, in reality, monomers are inseparable from raw materials and production processes. It is precisely because of the outdated nature of China’s calcium carbide-based production methods that there is still a significant difference in quality between monomers produced by this method and those produced by the oxychlorination method. The monomer mass of Heji is close to that of the oxychlorination monomer, making this process highly suitable for widespread adoption. It has great reference value for the current development of the calcium carbide method in China. The main methods for PVC production include the suspension method, bulk method, emulsion method, etc., among which the suspension method accounts for about 90%. The quality parameters of PVC resin produced by the suspension method include degree of polymerization, apparent density, fish-eye defects, residual VCM content, residue on sieves, volatiles, oil absorption rate, impurity particles, initial whiteness, and whiteness after thermal aging. There are many factors that affect the quality of PVC, and it cannot be simply said that the resin produced using a certain manufacturing process has better quality. Because although the mass of the monomer has a significant impact on the quality of the resin, it is not the sole determining factor. The quality of resin is also influenced by the polymerization process and post-treatment, as well as by the formula and additives, as well as by the level of automated control and management. In short, the key to improving the quality of monomers produced by the calcium carbide method lies in finding ways to enhance this process and raise its technical standards.