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:
Jan. 02, 2001
Filed:
Jan. 08, 1999
Robert M. Waymouth, Palo Alto, CA (US);
Raisa L. Kravchenko, Wilmington, DE (US);
Jennifer Maciejewski Petoff, Sunnyvale, CA (US);
The Board of Trustees of the Leland Stanford Junior University, Palo Alto, CA (US);
Abstract
This invention relates to high melting polyolefin copolymers suitable as thermoplastic elastomers and catalysts and methods for their synthesis. These elastomeric olefin copolymers are characterized by a mole fraction of crystallizable component X,from about 30 to about 99%; low glass transition temperatures, below −20° C., and typically below −50° C.; melting points above about 90° C.; high molecular weights; a molecular weight distribution M,/M,</=10; and a narrow composition distribution between chains of </=15%. The novel copolymers of the invention range from reactor blends to multiblock copolymers that can be sequentially fractionated into fractions of differing crystallinities, which fractions nevertheless show compositions of comonomers which differ by less than 15% from the parent polymer (reactor product). The invention also relates to a process for producing such copolymers by utilizing an unbridged, substituted or unsubstituted cyclopentadienyl metallocene catalyst that is capable of interconverting between states with different copolymerization characteristics, which interconversion is controlled by selecting the substituents of the cyclopentadienyl ligands so that the rate of interconversion of the two states is within several orders of magnitude of the rate of formation of a single polymer chain. Where r,>r,the polymer can be characterized as multiblock; where r,<r,, the result is a polymer blend and where r,/r,is close to 1, the resulting polymer is a mixture of blend and multiblock. The metallocene catalysts of the invention are able to interconvert between more than two states, with embodiments of four states being shown in FIG.