Shell Oil Comapny

Miguel Prado

Carma J Gibler

Linda R Chamberlain

A process for improving the color of selectively hydrogenated block copolymers modified with acid compound or derivatives thereof which comprises: (a) anionically polymerizing at least one conjugated diene, and, optionally, at least one vinyl aromatic hydrocarbon, to produce a block copolymer, (b) selectively hydrogenating the block copolymer, (c) subjecting the block copolymer to an acid wash, (d) subjecting the acid washed block copolymer to high efficiency water washing at a residence time of not less than 50 minutes and a water to polymer cement weight ratio of more than 0.2, and (e) grafting an acid compound or a derivative thereof onto the block copolymer.

Process for improving the color of selectively hydrogenated block

The present invention is an improvement upon a process for hydrogenating a diene polymer by contacting the polymer in the presence of hydrogen with a titanium hydrogenation catalyst. The improvement comprises preventing discoloration of the hydrogenated polymer by treating it with water, a peroxide or alcohol in the absence of oxygen and adding a non-phenolic antioxidant to the polymer.

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Sugarland, TX, United States of America

Miguel Prado