Process for the preparation of biaxially oriented polyester film
US5534215A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 1995 |
| Grant date | Jul 9, 1996 |
| Priority date | — |
| Expiry date | Oct 4, 2015 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2367/02
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A biaxially oriented polyester film with excellent levelling property is produced by the inventive process which comprises: (a) melt-extruding and extending biaxially a polyester resin to shape it into a film; (b) treating the film thermally under a condition that formulae (1), (2) and (3) are satisfied; and (c) relaxing the film at a temperature range of Tm-60.degree. C. to Tm-140.degree. C. during the step (b): EQU Tm-60.degree. C.<T1<Tm-10.degree. C. (1) EQU 50<T1-T2<100 (2) EQU 5<(T1-T2)/t<25 (3) wherein: PA1 Tm represents the melting point of the film (.degree.C.), PA1 T1 represents the initial temperature for the thermal treatment of the film (.degree.C.), PA1 T2 represents the terminal temperature for the thermal treatment of the film (.degree.C.), and PA1 t represents time for the thermal treatment (sec.).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.