The main function of PVC stabilizers is to delay or stop the degradation of plastics under the action of physical (heat, light) and chemical (oxygen, microorganisms) factors. Mainly include PVC heat stabilizer, light stabilizer and antioxidant, etc.
1. PVC heat stabilizer
Thermal stabilizers can delay or avoid plastic damage and further degradation caused by heat. Usually not stated, the heat stabilizer refers specifically to the stabilizer used in the processing of PVC and vinyl chloride copolymer, that is, the PVC heat stabilizer. PVC and vinyl chloride copolymers are heat-sensitive resins. They are very easy to release hydrogen chloride during heat processing, which in turn triggers thermal aging and degradation reactions. The types of heat stabilizers widely used in the industry generally include basic lead salts, metal soaps, organic tins, organic antimony and other main stabilizers, epoxy compounds, phosphates, polyols, and two Organic auxiliary stabilizers such as ketones.
2. Light stabilizer
Light stabilizers mainly inhibit or weaken the photodegradation of plastics and improve the weather resistance of plastic products. Ultraviolet rays in sunlight have the greatest damage to plastics. In addition, impurities or chromophores in polymers can also promote photooxidative degradation of polymers.
Light stabilizers are mainly used for polyolefins, and secondly for rubber-modified PS, PVC, PU, etc.
3. Antioxidant
Antioxidants can delay or inhibit the oxidative degradation of plastics. Antioxidants are the most important type of plastic stabilizing additives. Almost all-polymer resins involve the application of antioxidants.
Generally divided into main antioxidants and auxiliary antioxidants. The main antioxidant has the main function of capturing polymer peroxy free radicals; the auxiliary antioxidant has the function of decomposing polymer peroxy compounds, and is also called a "peroxide decomposer".