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US 6,646,035 B2Granted
Synergistic combinations of phenolic antioxidants
AssigneeClariant Finance (BVI) Limited
InventorsHarald Koch, Alexander Lichtblau, Matthias Zäh, Christoph Kröhnke
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Abstract
The invention relates to synergistic combinations of certain phenolic antioxidants in thermoplastic polymers, especially in polyolefin pipes and other thermoplastic molding materials which are in prolonged contact with water. The instant combinations lead to better resistance against oxidative degradation as measured in terms of oxidation induction times (OIT), color and other technically important parameters as known in the art.
Claims8
A stabilizer composition for thermoplastic polymers comprising
- a) a phenolic antioxidant bis-[3,3-bis-(4′-hydroxy-3′-tert.butyl-phenyl)-butanoic acid]-glycolester (I), and
- b) at least one phenolic antioxidant selected from the compounds (VII) or (VIII) tetrakismethylene(3,5-di-tert.butyl-4-hydroxyphenyl)-hydrocinnamate (VII) or octadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate (VIII),
- wherein the weight ratio of component a) to component b) is from 1:10 to 10:1.
Dependencies are inferred from the claim text.