Tamper-evident, differential pressure-thermoformed lidded plastic container
US4836407A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 4, 1987 |
| Grant date | Jun 6, 1989 |
| Priority date | — |
| Expiry date | Aug 4, 2007 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB65D2543/00842
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A container is provided in the form of a cup-like container body with a round mouth closed by a lid which becomes removably replaceable upon tearing away of a circumferentially extending tear strip which initially surrounds the mouth rim of the container body as a radially outer, integral part of the lid flange. As the lid is differential pressure-thermoformed, its radially outer region is formed into a generally inverted U-shaped structure which near the juncture of the base and radially outer leg of the inverted U, is provided, within the channel, with an inverted V-shaped notch of substantially diminished wall thickness to provide a line of weakness which preferably extends nearly fully around the circumference of the lid, but for at an angularly short tear-starting site. After the thermoforming step, and preferably in connection with triming the lid from the surrounding scrap portion of the sheet in which it was formed, a mechanical crimper axially collapses an initially radially outwardly concave annular portion of the radially outer leg of the inverted U, intermediate the vertical extent of that leg, with an upwardly, inwardly directed barb or hook which, cooperating with the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.