Study Of Polyol Co-Stabilizer And It's Mixture With Calcium Zinc Stabilizer

Polyvinyl chloride (PVC) is a heat-sensitive polymer resin, with degradation during molding. It is necessary to add some heat stabilizers to prevent or retard PVC from decomposition. Toxic lead stabilizers are widely used at present, and more and more non-toxic stabilizers such as calcium zinc stabilizers are focused on development and production to decrease the harmfulness of toxic stabilizers.This article studies the co-stabilization of polyols and their mixtures with calcium zinc stabilizers. The influence of the structure of polyol on co-stabilization was focused. Esterification on improving compatibility of polyol with PVC was studied and some other additives were added to improve the early-stage discolor and long-term stabilization of PVC. At last some new polyol co-stabilizers were designed and synthesized with better co-stabilization.The main appearance of PVC degradation is coloration from white to yellow, brown and black, caused by polyene structure of PVC and its complex with metallic ions. Polyol has excellent co-stabilization for its complexion function with metallic ions. The effect of co-stabilization of polyol was influenced by its structure and dispersion in PVC resin. Some methods of improving polyols on their compatibility, early discolor and long-term stabilization had been studied. Some results and conclusions of this article had importance for development of new polyol co-stabilizers and new non-toxic calcium zinc stabilizers. The main results and conclusions include:1. The influence of hydroxyl group number on the co-stabilizationBy evaluating the co-stabilization of different polyols with 2 to 6 hydroxyl group numbers, it had been tested that co-stabilization increases with the hydroxylgroup number increasing.2. The influence of ester structure on the co-stabilizationThe compatibility of polyol in PVC resin can be well improved by esterification, with the expensive of loses of co-stabilization. The compatibility was affected by the carbon chain length of aliphatic acid in ester. Some new esterificated polyols such as dipentaerythritol ester of mono 2-ethylheaxyl adipate are designed and synthesized with better co-stabilization, and the most improvement is on compatibility with excellent transparency.3. Improvement of Ca/Zn stabilizer on initial and long-term stabilizationIt was tested that DBM had better improvement on initial coloration and hydrotalcite had better improvement on long-term stabilization with polyol when used with calcium zinc stabilizers.4. Optimization and comparative experimentsCompared with epoxidized soybean oil and phosphite, polyols are better co-stabilizers. Compared with toxic lead stabilizer and expensive organic tin stabilizer, calcium zinc stabilizers show better total performance on stabilization, processability and price. Some stabilizer recipes for water-pipe were obtained by optimization.5. Co-stabilization mechanism of polyolPolyol is added to form complex with zinc ion, therefore retarding zinc chloride from accelerating decomposition and decreasing early coloration caused by complexion with polyene structure.