Plastic additives, also called plastic additives, are polymers (synthetic resins) Some compounds must be added during molding to improve its processing performance or to improve the insufficient performance of the resin itself. There are many ways to classify plastic additives, and the more popular method is to classify them according to their functions and effects. In categories with the same function, they are often further subdivided according to the mechanism of action or type of chemical structure.
Today I will give you a brief introduction to heat stabilizer, one of the plastic processing additives:
Heat stabilizer: During the processing and molding process of plastics, heat will be generated due to heating, friction or shearing, or the performance of plastic products will change due to heating during use. Go bad. In order to prevent the degradation and aging of plastics when heated, it is necessary to add a substance that prevents the plastic from decomposing and changing when heated. This substance is called a heat stabilizer. Mainly used for the processing of PVC resin.
Pure PVC resin is extremely sensitive to heat. When the heating temperature reaches above 90℃, slight thermal decomposition will occur; when the temperature reaches 120℃, That is, obvious thermal decomposition occurs, causing the color of the PVC resin to gradually deepen. The thermal degradation mechanism of PVC is very complex, but the essence of the thermal decomposition reaction of PVC is a series of reactions caused by the HCl removal reaction, which ultimately leads to the breakage of macromolecules.
Commonly used types of heat stabilizers: lead salt heat stabilizers (tribasic lead sulfate, dibasic lead phosphite, dibasic lead stearic acid Lead, basic lead carbonate, etc.); Metal soap heat stabilizers (zinc stearate, calcium stearate, magnesium stearate, etc.); Organotin heat stabilizers (sulfur-containing organotins, organotin carboxylic acids salt, etc.); rare earth heat stabilizer.
Common composite plastic heat stabilizers include: liquid barium zinc complex; the main components of non-toxic liquid calcium zinc stabilizer are calcium stearate, castorum Calcium sesoleate, zinc stearate, zinc ricinoleate, epoxidized soybean oil, UV absorbers, etc. Liquid calcium and zinc stabilizers generally use fatty acid calcium salts and zinc salts with fewer carbon atoms that are more soluble in organic solvents; liquid barium cadmium and liquid barium cadmium zinc composite stabilizers are mainly used for soft PVC products. of processing
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