Disclosed is a composition of matter which provides heat and color
stability to polyvinyl chloride resins, especially of the flexible type,
said composition consists essentially of (A) about 10 to about 40 parts by
weight of a zinc carboxylate; (B) about 50 to about 80 parts by weight of
an alkyl ester of thiodipropionic acid; and (C) abqut 5 to about 20 parts
by weight of a phenolic antioxidant. A PVC resin containing the above
composition of matter is also disclosed.