Resin compositions for producing biaxially oriented polypropylene films
AssigneeSunoco, Inc.
InventorsSehyun Kim, Michael Robert Stephans
Life of this patent
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Abstract
Polypropylene resin compositions are provided that are useful in the production of biaxially oriented polypropylene films (BOPPs). The resins of the present invention are blends of high crystalline (low solubles) polypropylene homopolymer and an ethylene/propylene random copolymer (RCP). These blends can be used to replace standard high solubles BOPP grade polypropylene homopolymers. In addition, the use of high crystalline polypropylene homopolymers in the blends imparts improved stiffness to the finished films while maintaining good processability of the blends.
Claims17
A resin composition suitable for processing into a biaxially oriented polypropylene film, the composition comprising:
- about 70% to about 95% by weight of a polypropylene homopolymer, said polypropylene homopolymer having less than 3% by weight xylene solubles;
- and
- about 5% to about 30% by weight of an ethylene/propylene copolymer, said ethylene/propylene copolymer containing from about 0.5% to about 7.0% ethylene by weight.
A biaxially oriented polypropylene film comprising:
- about 70% to about 95% by weight of a polypropylene homopolymer, said polypropylene homopolymer having less than 3% by weight xylene solubles;
- and
- about 5% to about 30% by weight of an ethylene/propylene copolymer, said ethylene/propylene copolymer containing from about 0.5% to about 7% ethylene by weight.
A method of producing a biaxially oriented polypropylene film, the method comprising:
- providing a resin composition comprising:
- about 70% to about 95% by weight of a polypropylene homopolymer, said polypropylene homopolymer having less than about 3% by weight xylene solubles, and
- about 5% to about 30% by weight of an ethylene/propylene copolymer, said ethylene/propylene copolymer containing from about 0.5% to about 7% ethylene by weight;
- extruding said resin composition into a cast sheet;
- and
- stretching said cast sheet in a first machine direction, and stretching said cast sheet in a second transverse direction, to produce a biaxially oriented film.
A method of producing a biaxially oriented polypropylene film, the method comprising:
- providing a resin composition comprising:
- about 70% to about 95% by weight of a polypropylene homopolymer, said polypropylene homopolymer having less than about 3% by weight xylene solubles, and
- about 5% to about 30% by weight of an ethylene/propylene copolymer, said ethylene/propylene copolymer containing from about 0.5% to about 7% ethylene by weight;
- extruding said resin composition into a tube;
- and
- stretching said tube in a first machine direction, and inflating said tube with a gas to stretch said tube in a second transverse direction, to produce a biaxially oriented film.
Dependencies are inferred from the claim text.