Fumitoshi Kojima

Studies on polymer stabilisers: Part I—A novel thermal stabiliser for butadiene polymers☆

Abstract 2-Tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate (Sumilizer GM) is shown to be a very effective stabiliser for thermal degradation of butadiene type polymers under an oxygen-free atmosphere. The stabilising mechanism is confirmed to be a unique bifunctional mechanism, which consists of polymer radical trapping by the acrylate group, followed by fast hydrogen transfer from intramolecular hydrogen-bonded phenolic hydroxyl groups to result in stable phenoxyl radicals.

Studies on polymer stabilizers: Part II. A new concept of a synergistic mechanism between phenolic and thiopropionate type antioxidants☆☆☆

Abstract 3,9-Bis(2-(3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy)-1, 1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5] undecane (Sumitomos new antioxidant: Sumilizer GA-80) is shown to have a very effective synergistic stabilizing effect in combination with thiopropionate type antioxidants. For synergistic stabilization, association of phenolic antioxidants with thiopropionate type antioxidants through hydrogen bonding is shown, by IR analyses and estimation of association equilibrium constant of a model system, to be an important factor.

Studies on polymer stabilizers: Part IV—Prevention of oxidative discoloration☆

By a model accelerated oxidative reaction and product analysis, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate (Sumilizer® GM) was found to give a stilbene quinone-type colored product through a quinone methide-type intermediate. The resistance of GM and its analogs against oxidative discoloration was remarkably improved by substitution with a bulky group at the para position to the phenolic OH group.