PURPOSE: To obtain the titled compsn. Having excellent thermal stability during melt processing, by blending vetamin E and ethylenediaminetetraacetic acid in combination, with a vinylidene chloride copolymer obtd. by adding vitamin E to its monomer.

CONSTITUTION: 0.0005W0.01pts.wt. (per 100pts.wt. of resulting copolmer) vitamin E is added to vinylidene chloride monomer. Then said monomer and a copolymerizable unsaturated monomer such as vinyl chloride or methyl acrylate are copolymerized to prepare a vinylidene chloride copolymer. 0.0005W0.2pts.wt. (in the combined amount with vitamin E added to the above monomer) vitamin E, 0.0005W0.2pts.wt. ethylenediaminetetraacetic acid and, if necessary, 0.0005W0.2 pts.wt. alkyl thiopropionate are blended with 100pts.wt. above copolymer to obtain the desired venylidene chloride resin compsn.