Method of producing an acylated cellulose film
US5695694A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 6, 1995 |
| Grant date | Dec 9, 1997 |
| Priority date | — |
| Expiry date | Jun 6, 2015 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC09K2323/06
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
An acylated cellulose film having a high optical isotropy and uniformity is produced by dissolving an acylated cellulose in a solvent substantially free from water and including, as a principal component, 1,3-dioxolane in a ratio in weight of the acylated cellulose to the solvent of 10/250 to 10/15; spreading the acylated cellulose solution on a film-forming surface of a support; and drying, for example, initially drying the spread solution layer on film-forming surface so as to reduce the content of the residual solvent in the resultant film to 5 to 30% by weight; removing the resultant residual solvent-containing film from the film-forming surface; and finally drying the removed film, while allowing the film to shrink in the transversal direction thereof, at a drying temperature controlled continuously or intermittently to a level satisfying the relationship (I): (Tg'-50.degree. C.).ltoreq.T.ltoreq.(Tg'+20.degree. C.) (I), wherein T is the drying temperature (.degree.C.) and Tg' is a glass transition temperature (.degree.C.) of the solvent-containing film, the temperature Tg' varying in response to the solvent content in the film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.