Processes and apparatus for making transversely drawn films with substantially uniaxial character
US7740470B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 18, 2007 |
| Grant date | Jun 22, 2010 |
| Priority date | — |
| Expiry date | Jul 20, 2027 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S425/041
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A stretcher for substantially uniaxially orienting a film includes a plurality of gripping members to hold opposing edge portions of the film, paths along which the gripping members travel to stretch the film in a stretching region, and a drive mechanism to convey the film and gripping members along a machine direction. At least a portion of the paths in the stretching region define diverging, curvilinear courses disposed in-plane. The paths are configured such that during the stretching an extent of uniaxial character, U, is between zero and unity and a minimum value of an extent of uniaxial character, U, is at least 0.70 over a final portion of the stretching after achieving a TDDR of 2.5. U is defined as U=(1/MDDR−1)/(TDDR1/2−1), wherein TDDR is greater than 4 at an end of the stretching region.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.