Patent US4294791A successfully refreshed from Google Patents.
US4294791A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing thermoplastic resin film of markedly reduced thickness unevenness
Assignee: Teijin Ltd
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Filing: 1979-12-26
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Granted: 1981-10-13
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Expires: 1999-12-26
Abstract
Abstract A process for producing a film of a thermoplastic resin, characterized in that the rotation of a cooling drum for cooling a molten film-like extrudate is controlled such that the variation rate (%) of instantaneous rotation under no load (as defined in the specification) is less than about 1%, and that the cooled film-like extrudate is withdrawn from the cooling drum so that substantially no tension in the subsequent stretching step is exerted on the film-like extrudate on the cooling drum. The process is preferably applicable to a film-forming apparatus which operates at high speeds. A film having markedly reduced thickness unevenness is produced.
Inventors
- 👤 Hiroshi Nouda
- 👤 Yoshiaki Tanihara
- 👤 Takashi Ikeda
- 👤 Ituo Ogiuchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 17:45
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/88; B29C48/911; B29C48/9135; B29C48/915; B29C48/917; B29C48/03; B29C48/07; B29C48/08; B29C48/914; B29C48/9155; B29C48/9165
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
116 words
In a process for producing a film of a thermoplastic resin which comprises extruding a molten thermoplastic resin in film form onto a rotating cooling drum through a die slit, cooling the film-like extrudate on the cooling drum, withdrawing the cooled film-like extrudate from the cooling drum, and then stretching it, the improvement wherein the rotation of the cooling drum is controlled such that the variation rate (%) of instantaneous rotation under no load defined by the following ##EQU3## is less than about 1%, and wherein said withdrawal of the cooled film-like extrudate is carried out so that substantially no tension in the subsequent stretching step is exerted on the film-like extrudate on the cooling drum.
Claim 2
Dependent Claim
116 words
In a process for producing a film of a thermoplastic resin which comprises extruding a molten thermoplastic resin in film form onto a rotating cooling drum through a die slit, cooling the film-like extrudate on the cooling drum, withdrawing the cooled film-like extrudate from the cooling drum, and then stretching it, the improvement wherein the rotation of the cooling drum is controlled such that the variation rate (%) of instantaneous rotation under no load defined by the following ##EQU3## is less than about 1%, and wherein said withdrawal of the cooled film-like extrudate is carried out so that substantially no tension in the subsequent stretching step is exerted on the film-like extrudate on the cooling drum.
Claim 3
Dependent Claim
26 words
The process of claim 1 wherein said withdrawal of the cooled film-like extrudate is carried out while it is loosened between said cooling and said stretching.
Claim 4
Dependent Claim
38 words
The process of claim 1 wherein said withdrawal of the cooled film-like extrudate is carried out by passing it over at least two free rolls and at least one dancer roll provided between said cooling and said stretching.
Claim 5
Dependent Claim
32 words
The process of claim 1 wherein said withdrawal of the cooled film-like extrudate is carried out by passing it through nip rolls of controlled speed provided between said cooling and said stretching.
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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) | 1984-10-12 | 1985-04-13 | 1985-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-12 | 1989-04-13 | 1989-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-12 | 1993-04-13 | 1993-10-13 | $7700.00 | Window Closed / Lapsed |