The production process of SG-7/SG-8 and SG-5 resins is basically the same, and the production equipment is exactly the same. The main differences are additive formula, polymerization temperature, reaction pressure and so on. The reaction temperature and pressure of SG-8 resin have basically reached the working pressure limit of polymerization kettle, and the reaction requirements are more stringent, and the requirements for operation, safety, technology and personnel quality 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 resins is the viscosity number, and there is little difference in other indexes, which is more dangerous than SG-7 resin in production.
The production cost of SG-8 resin SG-7 resin is basically the same, which will be slightly higher than that of SG-7 resin and not more than 15 yuan/ton. Most enterprises say that the cost of SG-8 is slightly higher than that of SG-5, but the cost spread of different enterprises is slightly different. Enterprises that need to switch to other models say that the cost of SG-8 model is slightly higher than that of SG-5 model 100- 150 yuan/ton, but enterprises with dedicated lines say that the cost of SG-8 and SG-5 is not much different.
In principle, the higher the model, the greater the hardness of the product:
PVC resin is an amorphous linear polymer compound. The higher the relative molecular weight, the higher the viscosity, the higher the molecular weight, the higher the tensile strength, impact strength and elastic modulus, but the fluidity and plasticity of the resin melt decrease. Viscosity number is usually used to represent the molecular weight of polymers, and polymer types are classified.
SG5(K-65, S 1000): pipes, profiles, plates, etc.
SG3(K-70, S 1300): Most of them are soft products, such as hoses, wires and cables, films, shoes, toys and auto parts.
SG7, SG8(K-60, S800, S700): pipe fittings, plates, containers, etc.