The PVC resin can be classified into two types, a loose […]
The PVC resin can be classified into two types, a loose type (XS) and a compact type (XJ), depending on the dispersant in the polymerization. The loose particle size is 0.1-0.2mm, the surface is irregular, porous, cotton-like, easy to absorb plasticizer, compact particle size is less than 0.1mm, surface is regular, solid, table tennis, difficult to absorb plasticizer, At present, more loose types are used. PVC can be divided into ordinary grade (toxic PVC) and sanitary grade (non-toxic PVC). Hygienic grade requires a vinyl chloride (VC) content of less than 10 × 10-6, which can be used in food and medicine. Different synthetic processes, PVC can be divided into suspension PVC and emulsion PVC.
According to the national standard GB/T5761-93 "Inspection standard for general-purpose polyvinyl chloride resin for suspension method", the suspension method PVC is divided into PVC-SG1 to PVC-SG8 eight kinds of resins, wherein the smaller the number, the greater the degree of polymerization, the molecular weight is also The larger the strength, the higher the melt flow and the more difficult the processing.
In the specific selection, when making soft products, PVC-SG1, PVC-SG2, and PVC-SG3 are generally used, and a large amount of plasticizer needs to be added. For example, a polyvinyl chloride film is made of SG-2 resin, and 50 to 80 parts of a plasticizer is added. When processing hard products, plasticizers are generally not added or added in small amounts, so PVC-SG4, PVC-SG5, PVC-SG6, PVC-SG7, and PVC-SG8 are used. For example, SG-4 resin is used for PVC hard pipe, SG-5 resin is used for plastic door and window profile, SG-6 resin is used for hard transparent film, and SG-7 and SG-8 resin are used for hard foamed profile.