Various types of heat stabilizers heat discoloration Comment

Ideal thermal stabilizer should also absorb HCL, remove the active site, the addition of a conjugated polyene chain, destruction carbenium salts and prevent auto-oxidation, etc., which does not produce a product of catalytic degradation of PVC. The actual result of  Circuit breaker  have different functions and behave in a different thermal stability characteristics, can be divided into early-type, long type, intermediate type and versatile four categories.

1) cadmium, zinc soap is typical of early-type heat stabilizers, can quickly absorb HCL, and Cd, Zn in the catalyst to effectively replace PVC chain carboxylate unstable chlorine atom, thereby effectively suppressing the initial degradation and coloring , but because of consumption of fast transformation products CdC12, ZnC12, but also off the HCL PVC efficient catalysts, which will lead to degradation of the material PVC vicious suddenly darkened, so long-term thermal stability.

2) barium, calcium soap is a typical long-term thermal stabilizers, only the function of absorbing HCL, PVC can not effectively suppress coloration, but the transformation products BaC12, CaC12 non-catalytic activity, does not cause a sudden black PVC, long-term heat stability better.

3) fatty acids, organic tin are intermediate, both absorbs HCL, can effectively replace PVC with chain carboxylate unstable chlorine atoms, and transformation products do not have catalytic activity.

4) an organotin mercaptide is a all-round characteristics in various mechanisms simultaneously stabilize PVC, transformation products nor a catalytic activity, thus both excellent initial and long-term thermal stability results.

3 is a kind of heat stabilizers to prevent or reduce the polymer in the course of processing by heat degradation or crosslinking, additives to extend the life of the composite material. Stabilizers commonly be divided into categories according to the main component base, fatty acid soaps, organic tin compounds, composite heat stabilizer and pure organic compounds.

1) base heat stabilizers: base with stabilizers is the "base" of the lead salt of inorganic and organic acids, such stabilizer having excellent heat resistance, weather resistance and electrical insulation properties, low cost , poor transparency, toxicity, the dosage is generally 0.5% to 5.0%.

2) fatty acid-based heat stabilizer: These heat stabilizers is defined by the fatty acid composition of roots and metal ion compounds, also known as metal soap-based heat stabilizer, and its performance with the radical species and metal ions, generally an amount of 0.1% ~ 3.0%.

3) Organic tin-based heat stabilizer: These heat stabilizers may be unstable PVC and chlorine atoms in the molecule to form a ligand, the ligand and the organic tin carboxylate group and a chlorine  circuit breakers replacement. Such heat stabilizers are characterized by high stability, good transparency, heat resistance, deficiencies are more expensive.

4) composite heat stabilizer: This class is the base class of heat stabilizers or metal soap-based compound and a liquid or solid organic tin-based compound, wherein the metal salts of calcium - magnesium - zinc, barium - calcium - zinc, barium - zinc and barium - cadmium; commonly used organic acids such as organic acids, naphthenic acid, oleic acid, benzoic acid and salicylic acid.

5) organic heat stabilizers: These heat stabilizers can be used alone except for a few main stabilizers (mainly nitrogen-containing organic compounds), but also includes high boiling polyols and phosphite, phosphite often associated with metal stabilizers used, composite materials can improve the weather resistance, transparency, improve the surface color.