The function mechanisam of PVC Ca Zn stabilizer
The Function Mechanism of PVC Calcium and Zinc Stabilizer
An unstable chlorine atom (such as allyl chloride) on its macromolecule chain during the processing of PVC
HCL, PVC color will change from colourless (Or white) ~ light yellow ~ orange ~ red orange ~ red brown ~ brown, so that the physical and chemical properties of PVC worse. The color of the PVC is the same as that of the other. Ca Zn stabilizer mechanism of action is: Zn soap as the main stabilizer, while replacing the active chlorine and the function of absorption of HCl, followed by the formation of metal chloride is a Lewis acid, can promote the de-HCI reaction. PVC will be in a very short period of time will occur malignant degradation, leading to "zinc burning" phenomenon. The reaction is: Zn (O2C - R) 2 + 2PVC - Cl ------ ZnCl2 + 2PVC - O - CO - R Therefore, zinc soap must be combined with synergistic stabilizers, mainly including stearic acid Soap. As calcium stearate non-toxic, so zinc soap and calcium stearate complex. Calcium soap only shows the role of capture HCI, can not replace the active chlorine, the formation of metal chloride on the HCI reaction without catalytic effect, but can effectively replace the zinc soap generated chloride, so that regeneration. The reaction is: ZnCl2 + Ca (O2C - R) 2 --------- Zn (O2C-R) 2 + CaCl2 Generally speaking, the increase of calcium soap content can improve the long-term stability of the product, but In addition, the zinc soap content is high, the initial coloring property of the product can be improved, but the other "zinc burning", and the long-term stability of the decline. Therefore, in the calcium and zinc composite stabiliser by selecting a reasonable calcium soap, zinc soap ratio, the use of its synergistic effect can achieve better stability.