Patent ID: 7550525

Claim:
A method of diminishing the tendency to cause discoloration on heating at 177° C. of an aluminum hydroxide-containing polyvinyl chloride composition, comprising the steps of: (A) mixing polyvinyl chloride with a masterbatch comprising aluminum hydroxide and at least one inorganic perchlorate salt selected from the group consisting of alkali metal perchlorates and alkaline earth metal perchlorates, said masterbatch containing from 7 parts by weight to 500 parts by weight of said perchlorate salt, calculated on a dry basis, per 100 parts by weight of aluminum hydroxide, and (B) adding to the mixture formed in (A) additional aluminum hydroxide such that the composition contains: (i) from 15 parts by weight to 150 parts by weight of aluminum hydroxide per 100 parts by weight of polyvinyl chloride, and (i) from 0.03 parts by weight to 3 parts by weight of said inorganic perchlorate salt per 100 parts by weight of aluminum hydroxide.