US3640790A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sealing plastic film
Assignee: NATIONAL TRUST Co A TRUST Co OF ONTARIO
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Filing: 1970-04-23
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Granted: 1972-02-08
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Expires: 1990-04-23
Abstract
Abstract A method of heat sealing layers of plastic film wherein the film layers are heated in contact until the plastic attains a flowable state, and the area of flowable plastic is then extended until the plastic separates. The molten plastic then retracts towards the unheated flank of the seal area to form matching bead seals. The method is applicable to automatic bagmaking machines.
Inventors
- 👤 Edward Kenneth Rowley
- 👤 Clayton Thomas Waugh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 10:12
CPC Classifications
B; B29; B29C; B29C66/00; B29C66/01; B29C66/05; B29C66/10; B29C66/13; B29C66/137; B29C65/00; B29C65/02; B29C65/18; B29C65/74; B29C65/743; B29C65/747; B29C65/7473; B29C66/11; B29C66/112; B29C66/1122; B29C66/40; B29C66/41; B29C66/43; B29C66/80; B29C66/83; B29C66/832; B29C66/8322; B65; B65B; B65B51/00; B65B51/10; B65B51/24; B29C66/70; B29C66/71; B29C66/81; B29C66/818; B29C66/8182; B29C66/81821; B29C66/90; B29C66/91; B29C66/914; B29C66/9161; B29C66/93; B29C66/934; B29C66/94; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1052; Y10T156/1054; Y10T156/12; Y10T156/1313
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
16 words
A method as claimed in claim 1 wherein the film is formed from polyethylene or polypropylene.
Claim 2
Dependent Claim
26 words
A method as claimed in claim 1 wherein the heated plastic at the seal position is extended by means engaging the unheated flanks of the seal.
Claim 3
Dependent Claim
20 words
A method as claimed in claim 1 which constitutes a steP in a process for the manufacture of plastic bags.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-07 | 1975-08-09 | 1976-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-07 | 1979-08-09 | 1980-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-07 | 1983-08-09 | 1984-02-08 | $7700.00 | Window Closed / Lapsed |