THERMAL STABILIZER FOR SYNTHETIC RESIN AND ITS USE

PURPOSE:To obtain a stabilizer useful for a synthetic resin containing a vinyl chloride polymer, having safety to environment, retarding yellowing and blackening development during heating, showing excellent thermal stabilization effect, by blending specific plural compounds in a prescribed ratio. CONSTITUTION:In mixing a polyvinyl chloride synthetic resin with compounds of formula I and II in the presence or absence of another additive and using the compounds as an improver for thermal stability, the blending ratio of the compound of formula I/II is selected in the range of 2.4-0.25 and the mixture is used. The total of the mixture of the compounds of formula I and II is preferably 0.1-9.0 pts.wt. based on 100 pts.wt. of the polyvinyl chloride synthetic resin raw material (plasticizer is included when exists).