Shrinkable polyamide film and process for its production
US4431705A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 24, 1982 |
| Grant date | Feb 14, 1984 |
| Priority date | — |
| Expiry date | Mar 24, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31938
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A shrinkable polyamide film useful for wrapping hams, sausages, etc. The shrinkable film has a hydrothermal shrinking ratio of at least 30% in both MD and TD and a hydrothermal shrinkage stress of from 300 to 700 g/mm.sup.2. The film is produced by a process which comprises biaxially stretching a substantially amorphous film composed of a copolymer of 6,6-nylon/6-nylon in a weight ratio of from 5/95 to 25/75 at a temperature of not higher than 120.degree. C. and at a stretching ratio of at least 2.5 times in both MD and TD, and subjecting the stretched film to stress relaxation at a temperature of from the stretching temperature to 170.degree. C., followed by winding it up. Further, a shrinkable film having an oxygen gas permeability of not more than 20 cc/m.sup.2 .multidot.24 hrs. atm. as well as the above properties may be obtained by coating a polyvinylidene chloride resin prior to the stretching so that its solid content after the stretching becomes to be at least 0.5 g/m.sup.2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.