Patent ID: 8426636

Claim:
A sterically bulky stabilizer of the formula: wherein R 1 to R 6 can be the same or different and represent H, —NH—(C═O)—R′, —(C═O)—NH—R′, —NH—R′, —NH—(C═O)—NH—R′, —O—(C═O)—R′, branched or linear alkyleneoxy chains, or —OR′, wherein R′ is predominantly a linear or branched alkyl or cycloaliphatic group that may contain heteroatoms within the alkyl groups, provided that at least one of R 1 to R 6 represents —COOH or —CONH 2 , at least one of R 1 to R 6 is hydrogen, and at least one of R 1 to R 6 represents a sterically bulky group comprising a moiety selected from the group consisting of: