US4264553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of underwater granulation
Assignee: Shell USA Inc
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Filing: 1978-03-03
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Granted: 1981-04-28
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Expires: 1998-03-03
Abstract
Abstract A process for extruding and granulating thermoplastic material comprises passing a thermoplastic melt through a face-cut extruder or melt pump having an insulated die plate where the insulated die plate consists of a die plate having on its face or as an integral part of the die plate which is in contact with the cooling liquid a member or portion having a plurality of cavities or pores which surround the extrusion holes, the cavities or pores being of a type that communicate with the cooling liquid. Also disclosed is the thermoplastic processing apparatus.
Inventors
- 👤 Hans K. Loo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 19:44
CPC Classifications
B; B29; B29B; B29B9/00; B29B9/02; B29B9/06; B29B9/065; B29B7/00; B29B7/30; B29B7/58; B29B7/582; B29C; B29C48/00; B29C48/03; B29C48/05; B29C48/25; B29C48/30; B29C48/345; B29B7/80; B29B7/82; B29B7/826; B29C48/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
118 words
A method for pelletizing a thermoplastic material which comprises: (a) heating the thermoplastic material to a melt, (b) extruding the melt into a cooling liquid through nozzles penetrating a die plate, maintaining the temperature of the portion of the die plate surrounding said nozzles at a sufficiently high temperature, above the boiling temperature of said cooling liquid, to prevent chilling the thermoplastic below its solidification temperature by maintaining vapor of said cooling liquid in a plurality of small cavities, not contiguous to said nozzles, in said die plate, said cavities being in communication with said cooling liquid, and (c) slicing the thermoplastic material exiting through said nozzles by a knife means which periodically moves across the die face.
Claim 2
Independent Claim
118 words
A method for pelletizing a thermoplastic material which comprises: (a) heating the thermoplastic material to a melt, (b) extruding the melt into a cooling liquid through nozzles penetrating a die plate, maintaining the temperature of the portion of the die plate surrounding said nozzles at a sufficiently high temperature, above the boiling temperature of said cooling liquid, to prevent chilling the thermoplastic below its solidification temperature by maintaining vapor of said cooling liquid in a plurality of small cavities, not contiguous to said nozzles, in said die plate, said cavities being in communication with said cooling liquid, and (c) slicing the thermoplastic material exiting through said nozzles by a knife means which periodically moves across the die face.
Claim 3
Dependent Claim
45 words
The process of claim 1, wherein said small cavities are open pores having a maximum diameter ranging from about 1 to about 3 millimeters and are present around said extrusion nozzles at a concentration of from about 10 to about 100 cavities per square centimeter.
Claim 4
Dependent Claim
17 words
The process of claim 1 where the part of the die face containing the cavities is metal.
Claim 5
Dependent Claim
10 words
The process of claim 3 where the coolant is water.
Claim 6
Dependent Claim
29 words
The process of claim 4 where the thermoplastic material is selected from the group consisting of polystyrene, polypropylene, polyvinylchloride, polyethylene and polystyrene/butadiene block copolymers or their partially hydrogenated derivatives.
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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) | 1984-04-27 | 1984-10-27 | 1985-04-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-04-27 | 1988-10-27 | 1989-04-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-04-27 | 1992-10-27 | 1993-04-28 | $7700.00 | Window Closed / Lapsed |