Shell Oil Comapny

Raymond C Tsiang

Ronald J Hoxmeier

Harvey E Atwood

Arthur R Bean

Gary W Richie, Deceased

A method for preparing asymmetric radial polymers wherein the different polymeric arms are contacted sequentially with a nonpolymerizable coupling agent. Contacting of the final step in the process, which frequently but not necessarily always will be the second step in the process, will be carried out in the presence of a polar compound suitable for increasing the amount of vinyl content in a conjugated diolefin polymer during polymerization thereof. The method used narrows the relative arm distribution of the several asymmetric radial polymers produced and significantly increases the amount of total product having the desired ratio of polymeric arms and accomplishes this objective in relatively short reaction time. Any nonpolymerizable coupling agent known in the prior art to be useful in the production of asymmetric radial polymers may be used in the method of this invention but nonpolymerizable coupling agents having from 3 to about 12 functional groups are most effective and nonpolymerizable coupling agents having 2 or 3 functional groups are most preferred. Useful polar compounds are, generally, selected from the group consisting of ethers, tertiary amines, pyridine and pyrolidene compounds.

Method for preparing asymmetric radial polymers

A process is provided for removing Group VIII metal hydrogenation catalyst residue from a polymer which comprises oxidizing the hydrogenation catalyst residue in the polymer, contacting the polymer with an aqueous solution of dicarboxylic acid and separating the hydrogenation catalyst residue from the polymer. Preferred dicarboxylic acids include adipic and azelaic acids. The amount of water contacted with the polymer cement is less than that which would form an aqueous phase. Solid particulates comprising hydrogenation catalyst metal form within minutes upon the addition of the aqueous dicarboxylic acid to the polymer cement.

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Sugarland, TX, United States of America

Raymond C Tsiang