US4548778A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of producing thermoplastic resin sheet or film
Assignee: Idemitsu Petrochemical Co Ltd
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Filing: 1983-09-26
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Granted: 1985-10-22
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Expires: 2003-09-26
Abstract
Abstract A method of producing a thermoplastic sheet or film characterized in that a molten thermoplastic resin sheet extruded through a T-die is cooled by introducing it into a multi-stage slit in which a cooling water is flowing. The water level in the first slit of the multi-stage slit is maintained at as low a level as possible. The method produces various advantages over conventional methods; for example, the sheet or film is free from unevenness in thickness, wrinkles, and curls, and is of high uniformity, and the sheet or film can be formed by high-speed molding of at least 10 m/min. The sheet or film is suitable for use in wrapping of, for example, foods and medicines.
Inventors
- 👤 Atsushi Fujii
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 09:28
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/88; B29C48/919; B29C48/03; B29C48/07; B29C48/08; B29C48/911; B29C48/9135; B29C48/001; B29C48/0018; Y; Y10; Y10T; Y10T428/00; Y10T428/13; Y10T428/1352
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
199 words
A method of producing a thermoplastic sheet or film, comprising: extruding a molten thermoplastic resin through a T-die to form an extruded sheet or film; passing said extruded sheet or film through a first stationary slit in which a cooling water is flowing, such that said sheet or film is contacted with cooling water in said first slit, said cooling water flowing in cocurrent substantially nonturbulent, laminar flow with said sheet or film to cool said sheet or film, and exiting said cooled sheet or film from said first slit; and then passing said exited cooled sheet or film through at least a second stationary slit in which a cooling water is flowing, said second slit being below and spaced from said first slit such that said sheet or film is contacted with cooling water in said second slit, said cooling water flowing in cocurrent, substantially non-turbulent, laminar flow with said sheet or film to further cool said sheet or film, and then exiting said further cooled sheet or film from said second slit; the flow rate of cooling water through said slits being at least equal to the running speed of said sheet or film through said slits.
Claim 2
Independent Claim
199 words
A method of producing a thermoplastic sheet or film, comprising: extruding a molten thermoplastic resin through a T-die to form an extruded sheet or film; passing said extruded sheet or film through a first stationary slit in which a cooling water is flowing, such that said sheet or film is contacted with cooling water in said first slit, said cooling water flowing in cocurrent substantially nonturbulent, laminar flow with said sheet or film to cool said sheet or film, and exiting said cooled sheet or film from said first slit; and then passing said exited cooled sheet or film through at least a second stationary slit in which a cooling water is flowing, said second slit being below and spaced from said first slit such that said sheet or film is contacted with cooling water in said second slit, said cooling water flowing in cocurrent, substantially non-turbulent, laminar flow with said sheet or film to further cool said sheet or film, and then exiting said further cooled sheet or film from said second slit; the flow rate of cooling water through said slits being at least equal to the running speed of said sheet or film through said slits.
Claim 3
Dependent Claim
21 words
The method of claim 1, wherein said extruded sheet or film is passed substantially vertically through said first and second slits.
Claim 4
Dependent Claim
17 words
The method of claim 2, wherein said first and second slits are arranged in substantially vertical alignment.
Claim 5
Dependent Claim
46 words
The method of claim 1, comprising first and second cooling water supply means supplying cooling water to said first and second slits, respectively, and wherein the water level in said first cooling water supply means is lower than that of said second cooling water supply means.
Claim 6
Dependent Claim
23 words
The method of claim 4, wherein the water level in said first cooling water supply means ranges up to about 10 mm maximum.
Claim 7
Dependent Claim
23 words
The method of claim 5, wherein the water level in said first cooling water supply means ranges up to about 7 mm maximum.
Claim 8
Dependent Claim
21 words
The method of claim 4, wherein said extruded sheet or film is passed substantially vertically through said first and second slits.
Claim 9
Dependent Claim
14 words
The method of claim 1, wherein only said first and second slits are provided.
Claim 10
Dependent Claim
21 words
The method of claim 8, wherein said extruded sheet or film is passed substantially vertically through said first and second slits.
Claim 11
Dependent Claim
30 words
The method of claim 1, wherein the flow rate of the cooling water through said slits is higher than the running speed of said sheet or film through said slits.
Claim 12
Dependent Claim
21 words
The method of claim 1, wherein the spacing between said first and second slits ranges from about 10 to 200 mm.
Claim 13
Dependent Claim
20 words
The method of claim 11, wherein the length of said second slit ranges from between about 5 to 100 mm.
Claim 14
Dependent Claim
19 words
The method of claim 12, wherein the length of said second slit ranges from about 30 to 50 mm.
Claim 15
Dependent Claim
25 words
The method of claim 1, comprising passing said sheet or film from said second slit through a cooling water tank spaced below said second slit.
Claim 16
Dependent Claim
36 words
The method of claim 1, comprising passing said sheet or film, after it exits through said second slit, over at least one guide roll to maintain said sheet or film substantially centrally located in said slits.
Claim 17
Dependent Claim
27 words
The method of claim 1, comprising passing said sheet or film through said first and second slits at a rate of at least 10 meters per minute.
Claim 18
Dependent Claim
46 words
The method of claim 1, comprising contacting both opposite sides of said sheet or film with cooling water as it passes through said first slit, and contacting both opposite sides of said sheet or film with said cooling water as it passes through said second slit.
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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) | 1988-10-21 | 1989-04-22 | 1989-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-21 | 1993-04-22 | 1993-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-21 | 1997-04-22 | 1997-10-22 | $7700.00 | Window Closed / Lapsed |