Some of the PVC heat stabilizer added in plastic processing has no lubricating effect, such as lead salt, organotin, organoantimony and rare earth, lubricant should be added in the formula. Some stabilizers themselves have lubricating effect, such as metal soap, the formula does not add or add less lubricant. Sulfur-containing organotin and organoantimony heat stabilizers cannot be used with Pb and Cd stabilizers, because sulfur contamination will occur when they are used together. Other additives used with PVC heat stabilizer are.
(1) During the processing and use of PVC antioxidant products, oxidation occurs due to the action of heat and ultraviolet light, and its oxidative degradation is related to the generation of free radicals. The main antioxidant is a chain break terminator or free group elimination agent. Its main function is to combine with the free group to form A stable compound, so that the chain reaction is terminated. The main antioxidant for PVC is generally bisphenol A. There are auxiliary antioxidants or hydrogen peroxide decomposition agents, PVC auxiliary antioxidants for triphenyl phosphite and phenyl diisooctyl phosphite. The combination of main and auxiliary antioxidants can play a synergistic role.
(2) UV absorbent PVC products used outdoors, due to its sensitive wavelength range of UV irradiation, PVC molecules into an excited state, or its chemical bonds are destroyed, causing free chain reaction, promote the degradation and aging of PVC. In order to improve the anti - UV ability, ultraviolet absorbent is often added. PVC commonly used UV absorbers are triazine -5, UV-9, UV-326, TBS, BAD, OBS. Triazine-5 is good, but the yellow color makes the film slightly yellow, which can be changed by adding a small amount of phthalocyanine blue. UV-9 is commonly used in PVC agricultural film, and the general dosage is 0.2~0.5. TBS and BAD of salicylic acid have mild effects with OBS, and good aging resistance can be obtained when combined with antioxidant. For non-transparent products, generally by adding shading rutile titanium dioxide to change the weather resistance, then if you add ultraviolet absorbent, you need a large amount, not very cost-effective.
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