Anti-yellowing composition

Claim 1

An anti-yellowing additive for minimizing the yellowing tendency when heated at 190° C. of environmentally acceptable stabilized vinyl chloride polymer compositions from which arsenic, cadmium, lead, mercury, and thallium are substantially excluded, comprising in combination (A) at least one basic inorganic oxide, hydroxide, phosphate, phosphite, nitrate, nitrite, or sulfate of at least one of the metals lithium, sodium, potassium, magnesium, calcium, strontium, barium, zinc, titanium, aluminum, zirconium, or tin having in the presence of 100 parts of water per part a pH in the range of 7.4 to 13; and (B) for each part by weight of basic inorganic compound 0.01 to 1 part by weight of a 1,3-diketone compound represented by the formula ##STR52## in which R is a hydrocarbon group, a halohydrocarbon group, an alkoxyhydrocarbon group or an alkylenedioxyhydrocarbon group or an alkylenedioxyhydrocarbon group having 1 to 18 carbon atoms; R' is a hydrogen atom, an acyl group ##STR53## where R"' is alkyl or a hydrocarbon group having 1 to 18 carbon atoms; R" is a hydrogen atom or a hydrocarbon group, a halohydrocarbon group, an alkoxyhydrocarbon group, or an alkylenedioxyhydrocarbon group having 1 to 18 carbon atoms; M is hydrogen or a metal selected from the group consisting of lithium, sodium, potassium, strontium, barium, zinc, aluminum, and antimony; and n is an integer from 1 to 3 depending on the valence of M.