US3622657A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming and cooling thermoplastic film
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1969-09-24
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Granted: 1971-11-23
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Expires: 1989-09-24
Abstract
Abstract A method for forming and cooling thermoplastic film. The film is extruded downwardly in a molten condition and passed through a cooling cell containing a cooling liquid. A first stream of cooling liquid is passed in contact with lower part of the film at a high velocity in countercurrent turbulent flow. A second stream of cooling fluid is passed in contact with the upper part of the film at a low velocity in cocurrent laminar flow. The first and second streams are withdrawn from a transistion zone adjacent to the surface of the film at a medial point of the film. The film may be in tubular form and passed over a cooling mandrel positioned within the cooling cell. Cooling air is passed upwardly through the inside of the film to expand the film and prevent condensation of volatiles on the mandrel.
Inventors
- 👤 Howard C North
- 👤 Charles W Williamson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 14:47
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/88; B29C48/90; B29C48/901; B29C48/903; B29C48/03; B29C48/09; B29C48/10; B29C48/902; B29C48/91; B29C48/911; B29C48/9115; B29C48/912; B29C48/9135; B29C48/914; B29C48/918; B29C48/9185; B29C2948/00; B29C2948/92; B29C2948/92504; B29C2948/9258; B29C2948/92704; B29C48/001; B29C48/0018; B29C48/0019; B29C48/07; B29C48/08; B29C48/885; B29C48/919
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
271 words
A process for the formation of a tubular thermoplastic film comprising: a. extruding a thermoplastic resin generally downwardly in the form of a molten, thermoplastic substantially tubular film body; b. passing said film body downwardly around a cooling mandrel positioned in a cell containing cooling liquid; c. directing cooling gas upwardly through an inside portion of said downwardlY moving film body prior to contact with said mandrel thereby partially cooling and simultaneously expanding said film body to a diameter larger than the diameter of said mandrel and preventing the condensation of volatile products on said mandrel at the point where the film contacts said mandrel; d. sliding the inside surface of said partially cooled, expanded tubular film body downwardly over the outer surface of said cooling mandrel whereby the inside surface of said tubular film is maintained in contact with at least a portion of said mandrel by pressure exerted by the cell cooling liquid and is cooled through contact with said mandrel; e. passing a first stream of cooling liquid in a turbulent zone in said cell at high relative velocity in countercurrent flow in contact with the lower portion of the outer surface of said film body; f. passing a second stream of cooling liquid in a quiescent zone in said cell at moderate relative velocity in cocurrent flow in contact with the upper portion of the outer surface of said film body; g. withdrawing said first stream and said second stream from a transition zone adjacent to the outer surface of said film body at a medial point on said mandrel, and h. thereafter recovering said tubular film.
Claim 2
Dependent Claim
28 words
A process for the formation of tubular thermoplastic film as claimed in claim 2 wherein said thermoplastic resin is selected from the group consisting of polypropylene and polyethylene.
Claim 3
Dependent Claim
33 words
A process for the formation of tubular thermoplastic film as claimed in claim 2 wherein said thermoplastic resin is polypropylene and the quiescent zone is at a cooler temperature than the turbulent zone.
Claim 4
Dependent Claim
33 words
A process for the formation of tubular thermoplastic film as claimed in claim 2 wherein said thermoplastic resin is polyethylene and the quiescent zone is at a warmer temperature than the turbulent zone.
Claim 5
Dependent Claim
30 words
A process for the formation of tubular thermoplastic film as claimed in claim 2 wherein said film body passes through a static zone prior to admission to said quiescent zone.
Claim 6
Dependent Claim
301 words
A process as claimed in claim 2 for the formation of a tubular polyethylene film comprising: a. extruding polyethylene generally downwardly in the form of a molten, thermoplastic substantially tubular film body; b. passing said film body at 160* C. to 235* C. downwardly around a cooling mandrel positioned in a cell containing cooling liquid; c. directing cooling gas upwardly through an inside portion of said downwardly moving film body prior to contact with said mandrel thereby partially cooling and simultaneously expanding said film body to a diameter larger than the diameter of said mandrel and preventing the condensation of volatile products on said mandrel at the point where the film contacts said mandrel; d. sliding the inside surface of said partially cooled, expanded tubular film body downwardly over the outer surface of said cooling mandrel whereby the inside surface of said tubular film is maintained in contact with at least a portion of said mandrel by pressure exerted by the cell cooling liquid and is cooled through contact with said mandrel; e. passing a first stream of cooling liquid in a turbulent zone in said cell at high relative velocity in countercurrent flow in contact with the lower portion of outer surface of said film body thereby cooling said polyethylene film to 3* C. to 60* C. f. passing a second stream of cooling liquid in a quiescent zone in said cell at moderate relative velocity in cocurrent flow in contact with the upper portion of the outer surface of said film body thereby cooling said polyethylene film to 30* C. to 95* C. g. withdrawing said first stream and said second stream from a transition zone adjacent to the outer surface of said film body at a medial point on said mandrel, and h. thereafter recovering said tubular film.
Claim 7
Dependent Claim
303 words
A process as claimed in claim 2 for the formation Of a tubular polypropylene film comprising: a. extruding a thermoplastic resin generally downwardly in the form of a molten, thermoplastic substantially tubular film body; b. passing said film body at 180* C. to 280* C. downwardly around a cooling mandrel positioned in a cell containing cooling liquid; c. directing cooling gas upwardly through an inside portion of said downwardly moving film body prior to contact with said mandrel thereby partially cooling and simultaneously expanding said film body to a diameter larger than the diameter of said mandrel and preventing the condensation of volatile products on said mandrel at the point where the film contacts said mandrel; d. sliding the inside surface of said partially cooled, expanded tubular film body downwardly over the outer surface of said cooling mandrel whereby the inside surface of said tubular film is maintained in contact with at least a portion of said mandrel by pressure exerted by the cell cooling liquid and is cooled through contact with said mandrel; e. passing a first stream of cooling liquid in a turbulent zone in said cell at high relative velocity in countercurrent flow in contact with the lower portion of outer surface of said film body thereby cooling said polypropylene film to 15* C. to 95* C. f. passing a second stream of cooling liquid in a quiescent zone in said cell at moderate relative velocity in cocurrent flow in contact with the upper portion of the outer surface of said film body thereby cooling said polypropylene film to 5* C. to 80* C. g. withdrawing said first stream and said second stream from a transition zone adjacent to the outer surface of said film body at a medial point on said mandrel, and h. thereafter recovering said tubular film.
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) | 1974-11-22 | 1975-05-24 | 1975-11-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-22 | 1979-05-24 | 1979-11-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-22 | 1983-05-24 | 1983-11-23 | $7700.00 | Window Closed / Lapsed |