Heat stabilization of vinylidene chloride resins

Polymers and copolymers of vinylidene chloride are stabilized against deterioration by heat in the presence of iron and its compounds by mixing therewith a substance selected from the group of polyglycols, primary and secondary aliphatic alcohols containing more than two hydroxyl groups and condensates thereof with themselves, with glycols and polyglycols, and partial esters and ethers of these compounds. Suitable copolymers are those of vinylidene chloride with vinyl halides, vinyl esters, acrylonitrile and its derivatives, styrene, chlorinated styrenes and methyl styrene, acrylic and methacrylic acid esters, vinyl ethers and ketones and sulphur analogues thereof, e.g. vinyl isobutyl sulphide, butadiene, isoprene and chloroprene. Among the stabilizers specified are di-, tri-, tetra- and penta-ethylene glycols, dipropylene glycol, ethylene propylene glycol; glycerine, pentaerythritol, mannitol, sorbitol; diglycerol, triglycerol and glycol ethers of glycerine, pentaerythritol and mannitol; triethylene glycol citrate, diethylene glycol tartrate, triethylene glycol glycolate, pentaerythritol ethers of ethylene glycol and sorbitol monoglycolate. At least one hydroxyl group must be present in these esters and ethers. The stabilized compositions may contain iron pigments and may be fused in iron-containing vessels in the manufacture, for example, of extruded filaments. Where pigments are used, the mixture of resin and pigment may be moistened with acetone before grinding with the stabilizer.