US4220683A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of thermoforming and product made therefrom
Assignee: Imperial Chemical Industries Ltd
•
Filing: 1978-11-02
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Granted: 1980-09-02
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Expires: 1998-11-02
Abstract
Abstract A method of thermoforming a thermo-plastics sheet carrying a protective layer of polyethylene on at least one of the surfaces of the sheet comprising heating the assembly of sheet together with its protective layer to above the softening point of the thermoplastic and subsequently stretching the assembly to a desired shape.
Inventors
- 👤 Peter J. Barker
- 👤 Gerald R. Cheal
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:08
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/002; B29C51/14; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1043; Y10T156/1044; Y10T156/1048; Y10T428/00; Y10T428/13; Y10T428/1352; Y10T428/24; Y10T428/24942; Y10T428/2495; Y10T428/24967; Y10T428/31504; Y10T428/31786; Y10T428/31797; Y10T428/31855; Y10T428/31909; Y10T428/31913; Y10T428/31928
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
77 words
A shaped article which has been shaped from a sheet of poly(methyl methacrylate) having a thickness of at least 3.0 mm, a reduced viscosity of at least 1.5 and carrying an adhered protective layer of polyethylene having a melt flow index as measured by ASTM Method 1238-70 of between 1 and 4 and having a thickness of at least 40 microns wherein the polyethylene is in intimate contact with at least one surface of the shaped article.
Claim 2
Dependent Claim
77 words
A shaped article which has been shaped from a sheet of poly(methyl methacrylate) having a thickness of at least 3.0 mm, a reduced viscosity of at least 1.5 and carrying an adhered protective layer of polyethylene having a melt flow index as measured by ASTM Method 1238-70 of between 1 and 4 and having a thickness of at least 40 microns wherein the polyethylene is in intimate contact with at least one surface of the shaped article.
Claim 3
Dependent Claim
20 words
A shaped article according to claim 1 in which the reduced viscosity of the poly(methyl methacrylate) is at least 3.0.
Claim 4
Dependent Claim
24 words
A shaped article according to claim 1 in which the article is an article of sanitaryware such as a bath, shower-tray or wash basin.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-09-02 | 1984-03-03 | 1984-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-02 | 1988-03-03 | 1988-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-02 | 1992-03-03 | 1992-09-02 | $7700.00 | Window Closed / Lapsed |