Coextrusion processes for making multilayer films and films made thereby
US9296182B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 8, 2007 |
| Grant date | Mar 29, 2016 |
| Priority date | — |
| Expiry date | Apr 21, 2030 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/263
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
The invention relates to a blown film coextrusion process. The process involves extruding core contact layers through a die exit at a specified speed and cooling, orienting and crystallizing the multi-layer film formed at a specified deformation rate to form a the frost line is a specified distance from the die exit by withdrawing film at a take up speed. The core and core contact layers are of a film forming polymer composition comprising at least 90 wt % of ethylene based polymer. The ethylene based polymer of the core layer has an average density of ethylene based polymers equal to or higher than that of ethylene based polymer of the core contact layers. The invention specifically concerns the feature that the core layer composition contains a portion of and the composition of the core contact layers contains a portion of a linear polyethylene so as to make the core layer more resistant to deformation than the skin layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.