Multi-layer, white cavitated bioriented polyethylene film with a high water vapor transmission rate
US6824864B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 23, 2001 |
| Grant date | Nov 30, 2004 |
| Priority date | — |
| Expiry date | Jan 25, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31938
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The present invention relates to bioriented polyethylene films having high water vapor transmission rates (WVTR) and methods for preparing the same. The film comprises a base layer and skin layers. The base layer comprises highly cavitated polyethylene, such as medium density polyethylene (MDPE) or high density polyethylene (HDPE). The cavitating agent in the base layer may be calcium carbonate. At least one skin layer comprises (i) a copolymer of ethylene and at least one other monomer and (ii) a hydrocarbon resin, such as a cyclopentadiene resin. This copolymer (i) may be an ethylene-propylene copolymer or an ethylene-propylene-butene-1 terpolymer. The film may have unidirectional tear properties in the machine direction. This film is particularly useful for packaging food products, such as pieces of candy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.