Basic informationPVC resin is a polar non-crystalline polymer, there is a strong force between molecules, is a hard and brittle material; Low impact strength.
After adding the impact modifier, the elastomer particles of the impact modifier can reduce the total stress induced by the silver grain, and use the deformation and shear band of the particles themselves to prevent the expansion and growth of the silver grain, and absorb the impact energy in the incoming material, so as to achieve the purpose of impact resistance. The particles of the modifier are small, so as to increase the number of modifiers per unit weight or per unit volume, so that the number of effective volumes is increased, thus enhancing the ability to disperse stress. At present, the organic impact modifier is widely used.
TYPE AND DIFFERENCEIn our country, the most common ones are SG-5, then SG-3, SG-7, SG-8, and so on. Compared with type 5, the reaction time required for the production of type 3 PVC is long, the polymerization temperature is high, the addition of auxiliary materials is high, and the production cost is 50-100 yuan/ton higher than that of type 5. Type 3 PVC purity is high, less fish eyes, easy to blister, with high temperature resistance, insulation, soft product texture and other characteristics, mainly used in the production of soft products such as wire and cable, agricultural film, conveyor belt, daily plastic products.
SG-7/SG-8 and SG-5 resin production process is basically the same, the production device is exactly the same. The main difference lies in the additive formulation, polymerization reaction temperature, reaction pressure and so on. The reaction temperature and reaction 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 quality of resin 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 the other indicators are not different, and the risk coefficient is greater than that of SG-7 resin in production. The production cost of SG-8 resin SG-7 resin is basically the same, will be slightly higher than SG-7, should not exceed 15 yuan/ton per ton. Most companies reported that the SG-8 cost was slightly higher than the SG-5, but the cost spread varied slightly between 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 between 100-150 yuan/ton, but enterprises that have dedicated lines of production said that the cost of SG-8 and SG-5 is not much different.
SG5 (K-65, S1000) : pipes, profiles, plates, etc.
SG3 (K-70, S1300) : mostly soft products, hoses, wires and cables, films, footwear, toys, auto parts;
SG7, SG8 (K-60, S800, S700) : pipe fittings, sheets, containers, etc.