The PVC plastic profile is mainly composed of PVC resin […]
The PVC plastic profile is mainly composed of PVC resin and additives. The additives are further divided into: heat stabilizer, lubrication agent, processing modifier, impact modifier, filler, ageing agent and colorant. Wait. Before designing a PVC formulation, you should first understand the properties of PVC resin and various additives.
Raw materials and additives
The resin for producing PVC plastic profiles is polyvinyl chloride resin (PVC). Polyvinyl chloride is a polymer made of vinyl chloride monomer. The output is second only to PE.
The PVC resin can be classified into two types, a loose type (XS) and a compact type (XI), 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, not easy to absorb Plasticizers are currently used more loosely.
PVC can be further divided into ordinary grade (toxic PVC) and sanitary grade (non-toxic PVC). Hygienic grade requires vinyl chloride (VC) content lower than lOXl0-6, 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-SGl to PVC-SG8Jk kinds of resins, wherein the smaller the number, the greater the degree of polymerization and the higher the molecular weight. Large, the higher the strength, but the more difficult the melt flow, the more difficult the processing. For specific selection, when using soft products, PVC-SGl, PVC-SG2, and PVC-SG3 are generally used, and a large amount of plasticizer is required. 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 added with little or no amount, so PVC-SG4, VC-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. The emulsion method PVC paste is mainly used for artificial leather, wallpaper, floor leather and plastic products. Some PVC resin manufacturers ship PVC resin according to the degree of polymerization (degree of polymerization is the number of unit links, polymerization degree multiplied by the molecular weight of the chain is equal to the molecular weight of the polymer), such as PVC resin produced by Shandong Qilu Petrochemical Plant, the factory products For SK-700; SK-800; SK-1000; SK-1100; SK-1200. The SG-5 resin has a polymerization degree of 1000-1100. The physical and chemical properties of PVC resin are shown in the fourth chapter.
The PVC powder is a white powder having a density between 1.35 and 1.45 g/cm3 and an apparent density of 0.4 to 0.5 g/cm3. The plasticizer content may be a soft or hard product. Generally, the plasticizer content is 0-5 parts as a hard product, 5-25 parts are semi-hard products, and more than 25 parts are soft products.
PVC is a non-crystalline, polar polymer with high softening temperature and melting temperature. Pure PVC generally needs to be plasticized at 160-210~C. Due to the polar bond between macromolecules, PVC is used. Shows hard and brittle performance. Moreover, the chlorine molecules in the PVC molecule, when the temperature reaches 120 ~ C, pure PVC will begin to dehydrogenation reaction, which will lead to thermal degradation of PVC. Therefore, it is necessary to add various additives to the processing and modification of the PVC and impact modification during processing, so that it can be processed into a useful product.
PVC resin is mainly used in the production of various types of film (such as daily printing film, industrial packaging film, agricultural greenhouse film and heat shrinkable film, etc.), various types of plates, sheets (the sheet can be used for plastic products), all kinds of pipes (such as non-toxic water pipes, construction threading pipes, transparent hoses, etc.), various profiles (such as doors, windows, decorative panels), hollow blowing bottles (for cosmetics and beverages), cables, all kinds of injection molded products and artificial leather , floor leather, plastic toys, etc.