Heat-shrinkable multilayer film
US6565985B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 26, 2001 |
| Grant date | May 20, 2003 |
| Priority date | — |
| Expiry date | Sep 26, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31746
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A polyamide resin-based heat-shrinkable multilayer film is caused to satisfy various properties required of a packaging material, especially a food packaging material, at high levels, and particularly exhibit a highest level of heat-shrinkability. The multilayer film comprises at least three layers including an outer surface layer (a) which comprises a polyester resin or a polyolefin resin; an intermediate layer (b) which comprises a mixture of 85-60 wt. % of an aliphatic polyamide resin, and 15-40 wt. % of an aromatic copolyamide resin which is a copolymer of aliphatic diamine/isophthalic acid and aliphatic diamine/terephthalic acid, and an inner surface layer (c) which essentially comprises a copolymer of ethylene and &agr;-olefin having a density below 0.915. The heat-shrinkable multilayer film has been biaxially stretched and then heat-treated to have hot-water shrinkabilities at 80° C. of at least 30% in each of longitudinal/transverse directions and at least 35% in at least one of longitudinal/transverse directions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.