Introduction and classification of PVC resin

Introduction and classification of PVC resin

PVC resin is a non-crystalline linear polymer compound. The greater its relative molecular mass, the higher the viscosity. The higher the molecular weight, the higher the tensile strength, impact strength and elastic modulus of the product. However, the flow of the resin melt Decreased sex and plasticity. The viscosity number is usually used to express the molecular weight of the polymer and classify the polymer model.

The most common ones in China are SG-5, followed by SG-3, SG-7, SG-8, etc. Compared with type 5, the production of type 3 PVC requires a long reaction time, high polymerization temperature, and high requirements for the addition of auxiliary materials. The production cost is 50-100 yuan/ton higher than that of type 5. Type 3 PVC has high purity, few fish eyes, easy blister, high temperature resistance, insulation, and soft product texture. It is mainly used in the production of soft products such as wires and cables, agricultural films, conveyor belts, and daily plastic products.

The production process of SG-7/SG-8 and SG-5 resin is basically the same, and the production equipment is exactly the same. The main difference lies in the additive formula, polymerization reaction temperature, reaction pressure, etc. The reaction temperature and reaction pressure of SG-8 resin have basically reached the working pressure limit of the polymerization reactor. The reaction requirements are more stringent, and the requirements for operation, safety, technology, personnel quality, etc. are more stringent, and the resin quality is more difficult to control.

In terms of product quality, the main difference between SG-8 and SG-7 resin is the viscosity number, and there is not much difference in other indicators. The production risk factor is greater than the production of SG-7 resin. The production cost of SG-8 resin is basically the same as that of SG-7 resin, which is slightly higher than that of SG-7 resin. It should not exceed 15 yuan/ton per ton. Most companies say that the cost of SG-8 is slightly higher than that of SG-5, but the cost spread varies slightly among different companies. Enterprises that need to switch production with other models said that the cost of SG-8 is slightly higher than that of SG-5 at 100-150 yuan/ton, but enterprises with dedicated production lines said that the cost of SG-8 and SG-5 is not much different.

In principle, the higher the model number, the harder the product.

SG5 (K-65, S1000): pipes, profiles, plates, etc.;

SG3 (K-70, S1300): mostly soft products, hoses, wires and cables, films, shoe materials, toys, auto parts;

SG7, SG8 (K-60, S800, S700): pipe fittings, sheets, containers, etc.