Biaxial orientation of thermoplastic film
Abstract
Abstract A continuous method for the production of biaxially oriented polypropylene film to produce an oriented film having uniform gauge and further characterized by having a high tensile modulus in the machine direction. The present method comprises extrusion of a molten base web into a pair of rotating nip rollers; passage of the polypropylene through the nip rollers into a quench bath whereby a solidified base film is formed, preheating the base film to an orientation temperature and thereafter stretching it in a transverse direction; subsequently stretching the transversely stretched film in the longitudinal direction. The temperature conditions during transverse direction orientation are maintained substantially isothermal as are the orientation temperatures during machine direction orientation, both transverse and machine direction orientation being accomplished within the confines of the single orientation chamber.
Inventors
- 👤 Robert E Fisher
Bibliographic Details
Claims Analysis
Total Claims: 0References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-07-11 | 1976-01-10 | 1976-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-07-11 | 1980-01-10 | 1980-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-07-11 | 1984-01-10 | 1984-07-11 | $7700.00 | Window Closed / Lapsed |