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:
Jun. 30, 1998
Filed:
Dec. 19, 1995
Ronald James Hoxmeier, Houston, TX (US);
Arthur R Bean, Jr, Houston, TX (US);
Shell Oil Company, Houston, TX (US);
Abstract
In the production of 'inside-out' star polymers where a first polymer lithium chain is formed, coupled and thereafter additional monomer is introduced to produce the 'out' polymer chains, improved control over the second polymerization is obtained by coupling with a mixture of a monoalkenyl-substituted aromatic compound and a polyalkenyl-substituted aromatic compound. For example, a mixture of divinylbenzene and styrene can be used. In another embodiment, an ether is introduced after completion of the first polymer chain formation. The presence of the ether also improves the second stage chain formation. Utilization of both the mixed coupling agents and the ether, preferably a diether such as 1,2-diethoxyethane gives the greatest control over the uniformity of the second stage polymerization, making possible the production of narrower molecular weight distribution polymer having no indication of bimodal distribution. The narrow molecular weight distribution is advantageous in many applications.