Process for making opaque polyester film
US9556540B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 20, 2009 |
| Grant date | Jan 31, 2017 |
| Priority date | — |
| Expiry date | Oct 25, 2030 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T442/30
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The invention relates to a process for making an opaque and glossy film from a thermoplastic polyester composition, comprising the steps of a) extruding the polyester composition through a slot die, and quenching to form a substantially amorphous film having a crystallinity of at most 5%; b) rapidly heating the amorphous film to a drawing temperature in the range from Tg to (Tg+50)° C. while applying a draw ratio in the range of from λinitiation to λmax. in longitudinal direction, and a drawing rate of at least 1 m/min to form an oriented film showing stress-whitening, wherein λinitiation is the draw ratio at which a transfer from a transparent product to a stress-whitened product occurs and λmax. is the draw ratio at which failure of the stress whitened film occurs; and c) heat-setting the oriented stress-whitened film; the thermoplastic polyester composition substantially consisting of at least one crystallizable polyester derived from at least one aliphatic diol and at least one aromatic dicarboxylic acid.With this process it is possible to make a unitary, glossy, opaque film from a polyester composition that does not contain void-forming additives like high amounts of fine pigm…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.