Polypropylene composition useful for making solid state oriented film
US6037417A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 18, 1998 |
| Grant date | Mar 14, 2000 |
| Priority date | — |
| Expiry date | Aug 18, 2018 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08L2205/02
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
Disclosed is a polypropylene composition useful for making solid state oriented film. The composition comprises two predominantly isotactic polypropylenes with the melting point temperature of one of the polypropylenes being substantially lower than the melting point temperature of the other. In one embodiment of the composition the higher melting point polypropylene is made by Ziegler-Natta catalysis, while the lower melting point polypropylene is made by metallocene catalysis. Compared to polypropylene with similar melt flow rate and made by Ziegler-Natta catalysis, and solid state oriented film thereof, the composition provides a better balance of elevated temperature draw characteristics and physical properties of oriented film made therefrom. Thus, at the same or lower elevated temperature yield stress, oriented film of the composition exhibits improved properties such as stiffness, elongation-at-break, dimensional stability, and oxygen barrier. Also disclosed is a method for the manufacture of oriented, flexible packaging film. In the method a cast sheet is melt extruded from the composition, and, after cooling until it is solid, the cast sheet is stretched to the desired ext…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.