Process for producing thermoplastic resin films having reduced thickness unevenness
US4129630A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 1976 |
| Grant date | Dec 12, 1978 |
| Priority date | — |
| Expiry date | Mar 29, 1996 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB29C2948/92904
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A process for producing a film of reduced thickness unevenness which comprises extruding a thermoplastic resin from an extrusion die into a film form, exposing the extrudate to an electric field induced by an electrostaticity applying electrode, and then pinning it to the surface of a cooling drum, wherein a shielding object is disposed between the extrusion surface of the die and the electrostaticity applying electrode thereby to maintain the applied voltage constant in the widthwise direction of the extrudate and to enable the extrudate to adhere intimately to the surface of the cooling drum, and an apparatus for producing a film of reduced thickness unevenness comprising an extrusion die equipped with means for adjusting the thickness unevenness of the film by temperature control, an electrode for applying electrostaticity, a cooling drum and a shielding object, said shielding object being a conductive object, a non-conductive object or a combination of these, and being disposed between the extrusion surface of the die and the electrostaticity applying electrode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.