By type and mechanism of PVC heat stabilizers brief

 Type of plastic heat stabilizer is a kind of heat stabilizers can prevent or reduce the polymer is heated in the course of processing and degradation or cross-linking additives to extend the life of the composite material. Usual stabilizers can be divided into categories according to the main component of salt, fatty acid soaps, organotin compounds, heat stabilizers, and the pure compound classes of organic compounds.
   Heat stabilizers salt: salt stabilizer is the combination of the "base" of lead salts of inorganic  acrylic processing and organic acids, such stabilizer having excellent heat resistance, weather resistance and electrical insulating properties, low cost, transparent poor, there is a certain toxicity, dosage is generally 0.5% to 5.0%. Fatty acid based heat stabilizer: Such a thermal stabilizer is a compound consisting of a fatty acid with magnesium hydroxide  a metal ion root, also known as hot metal soap stabilizers, its performance and the kind of metal ions and acid radicals, generally in an amount of 0.1% to 3.0 %.
 Composite heat stabilizer: Such a thermal stabilizer is a metal salt or soap as a kind of liquid or solid based and organic tin compound-based compound, wherein the metal salts are calcium - magnesium - zinc, barium - calcium - zinc, barium - zinc and barium - cadmium; common organic acids such as organic acids, naphthenic acid, oleic acid, benzoic acid and salicylic acid.
  Organic heat stabilizers: Except for a few of such primary heat stabilizer stabilizer may be used alone (primarily nitrogen containing organic compound), but also a high boiling point include polyhydric alcohols and phosphites, phosphates and metal stabilizers often and with agents that can improve weather resistance, transparency of the composite material, to improve the surface color of the article. Mechanism of pvc heat stabilizers and absorption HCL, inhibit autocatalysis. Such stabilizers include lead salts, organic acid metal soaps, organic tin compounds, epoxy compounds, phenol salts and metal thiolate. They can react with HCL, HCL off PVC suppression response. PVC substitution labile allylic chlorine in the molecule atom suppression de PVC. Organotin stabilizers such as ligand binding molecules and instability occurs PVC chlorine atom, a ligand, a chlorine atom with an unstable organotin substitution. An addition reaction with the polyene structure, the formation of large conjugated system damage and reduce coloration. Unsaturated acid salts or esters containing double bonds, and the PVC molecules conjugated diene double bond addition reaction, thereby destroying the structure of the conjugate, inhibiting discoloration.
Capturing free radicals and prevent the oxidation reaction. As the phenolic heat stabilizer can be added to titanium dioxide  block off the HCL, because phenol can be given by H atoms and radical degradation of PVC macromolecular radical coupling, not react with O2 forming material, and a heat stabilizing effect. Such a thermal stabilizer, one or both may have several roles. Ideal for PVC heat stabilizers should be a versatile substance, or a mixture of some of the material, they are able to perform the following functions: First, replacement lively, unstable substituents; second is to absorb and neutralize the release of PVC processing HCL, eliminating autocatalytic degradation of HCL; Third neutralize or inactivate catalytic degradation of metal ions and other harmful impurities; Fourth, through various forms of chemical reactions can be blocked unsaturated bond continues to grow, inhibiting degradation coloring; five is the best shield against ultraviolet protective effect. Generally, heat stabilizers according to their performance with the use of special, very little is used alone, but most of the species in a powder form, some of which are highly toxic chemicals. For ease of use, to prevent dust poisoning, reduce toxic substances or substitute non-toxic substances, at home and abroad in recent years developed a wide variety of composite stabilizer, for example, the world famous German brand composite stabilizer Bear series, the United States, Germany, Japan, Netherlands and other countries, or organotin compound organotin stabilizers have a considerable market in China. Therefore, the development of China's efforts to promote the use of high efficiency, low cost, no dust pollution and toxic or low toxicity of new composite stabilizer is an urgent need for the development of China's plastics industry.