The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 01, 1994
Filed:
Sep. 10, 1993
Michael A Masse, Richmond, TX (US);
Steven S Chin, Houston, TX (US);
Craig A Stevens, Houston, TX (US);
Shell Oil Company, Houston, TX (US);
Abstract
A process for preparing a coupled asymmetric block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene which comprises: (a) adding sufficient anionic polymerization initiator to the vinyl aromatic hydrocarbon monomer to start polymerization of the vinyl aromatic hydrocarbon, (b) polymerizing the vinyl aromatic hydrocarbon for a time sufficient to form a first set of vinyl aromatic hydrocarbon blocks having a desired molecular weight, (c) adding sufficient anionic polymerization initiator to start polymerization of a second set of vinyl aromatic hydrocarbon blocks, (d) completing the polymerization of the vinyl aromatic hydrocarbon for a time such that the first set of vinyl aromatic hydrocarbon blocks continues to grow to the desired molecular weight and the second set of vinyl aromatic hydrocarbon blocks grows to a desired smaller molecular weight, (e) adding a conjugated diene and polymerizing it on the ends of the vinyl aromatic hydrocarbon blocks for a time sufficient to form vinyl aromatic hydrocarbon-conjugated diene arms of the desired molecular weight, and (f) adding a coupling agent and coupling the arms to form the asymmetric block copolymer.