Patent US3608058A successfully refreshed from Google Patents.
US3608058A
Expired / Lapsed
US
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Method for manufacture of void-free and warp-free slab stock
Assignee: Shell USA Inc
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Filing: 1969-09-11
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Granted: 1971-09-21
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Expires: 1989-09-11
Abstract
Abstract Void-free slabs or billets of thermoplastic polymer are produced by cooling polymer melt in a mold under pressure while keeping part of the melt in contact with a heat-insulating deformable surface of the mold cavity.
Inventors
- 👤 Paul M Coffman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:33
CPC Classifications
B; B29; B29C; B29C43/00; B29C43/32; B29C43/54; B29B; B29B11/00; B29B11/06; B29B11/12
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
27 words
The method according to claim 1 wherein said polymer is crystallizable polyolefin and the thickness of said article is in the range from one-fourth to 2 inches.
Claim 2
Dependent Claim
27 words
The method according to claim 2 wherein said polymer is polypropylene and said molten polymer is at a temperature in the range from 385* to 535* F.
Claim 3
Dependent Claim
108 words
The method according to claim 1 wherein said heat-insulating body is an elastomer ring having flat top and bottom surfaces, a height 1.15 to 1.35 times that of said molded article, a concave inner wall, a straight outer wall, at least four grooves in its upper surface, spaced about equally from each other and having a depth no more than 15 percent of the height of said molded article, said elastomer ring being supported by a concentric outer rigid backup ring which has a height one-fourth to three-fourths that of said molded article and is centered substantially equidistant from the Top and bottom surfaces of said elastomer ring.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |