US 6,806,316 B2 · Propylene polymers for oriented films

Abstract

This invention relates generally to crystalline polypropylene polymers and methods for their production. Specifically, this invention relates to crystalline polypropylene polymer compositions comprising both propylene homopolymers and propylene copolymers. The compositions are prepared using metallocene catalyst systems comprising at least two metallocenes in a polymerization process that involves the sequential or parallel polymerization of propylene homopolymers and copolymers using propylene with a small amount of comonomer, preferably ethylene. The resulting polymers are excellent for use in the production of biaxially oriented films. Films prepared with these propylene polymers have a significantly broader processability range and can be evenly stretched at lower temperature compared to films prepared from traditional polypropylene polymers.

Claims16

Dependent claims

A crystalline propylene polymer composition comprising:

(a) from 10 to 90 weight percent of a crystalline propylene homopolymer composition comprising a first propylene homopolymer and a second propylene homopolymer;
and
(b) from 90 to 10 weight percent of a crystalline propylene copolymer composition comprising a first propylene copolymer and a second propylene copolymer, the first propylene copolymer and second propylene copolymer comprising from 0.05 to 15 weight percent of a comonomer based on the total weight of the crystalline propylene polymer composition;
wherein the crystalline propylene polymer composition has a molecular weight distribution (Mw/Mn) in the range of from 2.1 to 10;
and
wherein the propylene homopolymer composition and the propylene copolymer composition are obtained in separate stages using a single metallocene catalyst system comprising two different metallocene catalyst components.

3 more elements

Dependencies are inferred from the claim text.

Propylene polymers for oriented films

Life of this patent

Propylene polymers for oriented films

Life of this patent

Abstract

Claims16