Definition and principle of PVC thermal stabilizer

Definition and principle of PVC thermal stabilizer

In a broad sense, all additives that improve the thermal stability of polymer are called thermal stabilizers. Because of the poor thermal stability of PVC, most PVC stabilizers in the world are used for PVC. Therefore, PVC stabilizers are usually referred to as the thermal stabilizers of PVC and copolymer.

It is classified according to the chemical composition of the heat stabilizer, which can be used as alkali lead salt, metal soap, organic tin, epoxide, phosphite, polyol, etc. The PVC stabilizer can be divided into stabilizing agent and adjuvant stabilizer. The auxiliary stabilizer itself has only a small stabilizing effect or no thermal stability effect, but it has synergistic effect with the main stabilizer. Primary stabilizer is generally a thermal stabilizer containing metal. And epoxides, phosphatates, polyols and other pure organic compounds are generally used as adjuvant stabilizers.

Because to achieve the good stability of polyvinyl chloride (PVC) often need to use a variety of PVC heat stabilizer at the same time, so some items of PVC stabilizer is by a variety of composition distribution, become a composite stabilizer, stabilizing agent, such as barium cadmium zinc barium stabilizer and so on, these complex stabilizer usually have joined the lubricant additives, such as PVC processing needed to facilitate users. Compound stabilizer variety many, have powdery, paste, liquid, three kinds of form.

(1) absorption of hydrogen chloride

Me (OOCR) 2 + 2 HCL = = = MeCl2 hoocr + 2

Among them: Pb, Ba, Cd, Ca, Zn, Sn, Sb, Mg, Sr, etc.

(2) remove unstable chlorine atoms and eliminate unstable chlorine atoms.

(3) it is easy to be degraded by O2 oxidation under the action of thermal oxygen and shear.

(4) adding metal salts to maleic acid can inhibit or eliminate double bonds or make them shorter and less.