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US3734984A Expired / Lapsed US ⏱️ 0.0 years remaining

Process of extruding melted polymeric thermoplastic materials

Assignee: Eastman Kodak Co
•
Filing: 1971-05-04
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Granted: 1973-05-22
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Expires: 1991-05-04
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Abstract

Abstract A molten polymeric plastic such as a sheet of poly(ethylene terephthalate) is extruded under pressure through an orifice while impinging a blast of clean hot air or other gas against the extruded product at the instant it leaves the orifice. Water vapor is introduced into the gas, as by steam injection or water sprays, so as to maintain its humidity at a level corresponding to a dew point of at least 35*F., and preferably 50*-80*F. When casting a sheet of film onto a wheel, die lines are avoided by this process. The apparatus comprises a humidistat for monitoring the humidity of the air fed to the blast, a valve for controlling the injection of steam into the air, and a control system between the humidistat and valve for automatically maintaining the desired humidity.

Inventors

  • 👤 E Hoffman

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-31 18:26
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; B29C48/27; B29C48/272; B29C48/914

Claims Analysis

Total Claims: 10
Claim 1
Independent Claim 16 words
In the process of claim 1, introducing said water vapor by injecting steam into said gas.
Claim 2
Dependent Claim 16 words
In the process of claim 1, introducing said water vapor by evaporating water into said gas.
Claim 3
Dependent Claim 30 words
In the process of claim 1, introducing said water vapor in amount sufficient to raise the dew point of said gas to such a desired value between 50* and 80*F.
Claim 4
Dependent Claim 10 words
In the process of claim 1, said gas being air.
Claim 5
Dependent Claim 19 words
In the process of claim 1, monitoring the humidity of said gas prior to impingement thereof against said product.
Claim 6
Dependent Claim 34 words
In the process of claim 6, in said monitoring step, generating a signal representing the dew point of said gas, and controlling the introducing of said water vapor automatically in response to said signal.
Claim 7
Dependent Claim 43 words
In the process of claim 1, extruding said thermoplastic through an elongated narrow extrusion orifice and forming said product as a sheet of film, and impinging said blast of clean gas against the full width of at least one surface of said sheet.
Claim 8
Dependent Claim 11 words
In the process of claim 8, said thermoplastic being poly(ethylene terephthalate).
Claim 9
Dependent Claim 38 words
A process in accordance with claim 1 wherein said hot gas is at a temperature between about 400*F. and 650*F., and impinges against the extruded product at a velocity of between about 4,000 and 7,000 feet per minute.
Claim 10
Dependent Claim 56 words
A process in accordance with claim 8 in which the extruded film is deposited onto and taken away from the extrusion orifice by a moving casting surface transversely of which said extrusion orifice extends, and in which the blast of clean hot gas impinges against said sheet prior to deposition thereof on said moving casting surface.

References Cited (Backward Citations)

US2878521A Cited
US3277227A Cited
US3502757A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1976-05-21 1976-11-20 1977-05-22 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1980-05-21 1980-11-20 1981-05-22 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1984-05-21 1984-11-20 1985-05-22 $7700.00 Window Closed / Lapsed

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