Opaque polymeric films and processes for making same
US6183856A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 25, 1996 |
| Grant date | Feb 6, 2001 |
| Priority date | — |
| Expiry date | Jul 25, 2016 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/249993
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A process for making an opaque, oriented polymeric film structure and the resultant film structures. The process comprises preparing a melt containing a crystallizable polymeric matrix material at a temperature of at least above the melting point of the polymeric matrix material and thereafter forming the melt into a sheet containing molten polymeric matrix material. The sheet containing molten material is then cooled to form a sheet containing amorphous polymeric matrix material and crystallites of the polymeric matrix material. The sheet while containing the amorphous polymeric matrix material is then formed into a film by stretching the sheet in at least one direction so as to form voids adjacent to at least some of the crystallites and thereby impart opacity to the film. Film structures made by the above process have a plurality of voids, at least some of the voids not containing a void-initiating particle and at least some of the voids being interconnected with an adjacent void in the polymeric matrix material, the number of voids being sufficient to impart a significant degree of opacity in the film structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.