Pretreatment of thermoplastic film for improved sealing
US4070222A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 2, 1977 |
| Grant date | Jan 24, 1978 |
| Priority date | — |
| Expiry date | Mar 2, 1997 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T156/1313
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method is provided for the pretreatment of superposed layers of thermosplastic film which are to be heat sealed together, longitudinally, along a predetermined area. The film layers to be heat sealed are preheated utilizing heated air along a defined, continuous longitudinally extending area of the film layers. The preheated area is subsequently passed through a slit-seal device which simultaneously severs the preheated film layers and seals the severed edges together. The method is particularly useful for the slit-sealing of a continuously advancing flattened tube of thermoplastic which is characterized by having a non-uniform gauge in cross-section.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.