Method for ultrasonically sealing a plastic film composed of polypropylene
US6296727A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 17, 2000 |
| Grant date | Oct 2, 2001 |
| Priority date | — |
| Expiry date | Mar 17, 2020 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T156/108
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
Abstract
A method of making a cover comprising a pair of welded thermoplastic polymer sheets having therebetween a stiffener. A stiffener is provided such that the stiffener has a leading edge, a trailing edge, and two side edges. A pair of thermoplastic polymer sheets are positioned on opposite sides of the stiffener. The thermoplastic polymer sheets each have two side edges substantially parallel to the side edges of the stiffener. The thermoplastic polymer sheets are ultrasonically welded around the periphery of the stiffener. The polymer sheets are cut to form a leading edge and trailing edge which are substantially parallel to the leading edge and trailing edge of the stiffener. The thermoplastic polymer is typically selected from the group consisting of polypropylene and a copolymer of ethylene or butene and propylene, the weight percent of ethylene or butene being between about 1 wt. % to about 10 wt. %, and containing a sufficient amount of a nucleating agent to raise the recrystalization temperature to between about 100.degree. C. to about 140.degree. C.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.