Dimensionally stable polyimide film and process for preparation thereof
US4725484A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 1986 |
| Grant date | Feb 16, 1988 |
| Priority date | — |
| Expiry date | May 16, 2006 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/31721
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A dimensionally stable polyimide film and processes for the preparation thereof. The polyimide film is composed of an aromatic polyimide obtained from a solution of a polymer formed by polymerization of a biphenyl-tetracarboxylic acid and a phenylene diamine, wherein the average linear expansion coefficient of the polyimide film in the temperature range of from 50.degree. C. to 300.degree. C. is 0.1.times.10.sup.-5 to 2.5.times.10.sup.-5 cm/cm..degree.C., the ratio of the linear expansion coefficient in the machine direction of the film to the linear expansion coefficient in the transverse direction of the film is in the range of from 1/5 to 4, and the thermal dimension stability expressed by the ratio of the change of the size of the film at normal temperature after the heat treatment where the temperature is elevated to 400.degree. C. from normal temperature and the film is maintained at 400.degree. C. for 2 hours is less than 0.3%.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.