US3620368A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Classification of dry polymer beads
Assignee: Dart Industries Inc
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Filing: 1969-06-02
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Granted: 1971-11-16
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Expires: 1989-06-02
Abstract
Abstract A method for classifying dry polymer beads according to size comprises feeding the beads to a screening zone which is equipped with at least one screen having its surface composed of a material such as poly (tetrafluorethylene) which has a dielectric constant similar to that of the polymer and having openings of the desired size, passing the beads across the surface of the screen and passing a portion of the beads through the openings. As a result of this method, the beads are substantially free of a charge of static electricity and the portion passes through the openings in the screen without significantly blinding the openings.
Inventors
- 👤 William P Comis
- 👤 Lawrence E White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:14
CPC Classifications
B; B07; B07B; B07B1/00; B07B1/46
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
16 words
The method of claim 1 wherein said beads are composed of polymers of vinyl aromatic compounds.
Claim 2
Dependent Claim
12 words
The method of claim 2 wherein said beads are composed of polystyrene.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein said screen has at least its surface composed of a hydrocarbon consisting of poly (chlorotrifluoroethylene), fluorinated ethylene-propylene copolymer or poly (tetrafluoroethylene).
Claim 4
Dependent Claim
157 words
A method for classifying dry, substantially spherical polystyrene beads having an average particle size in the range from about 10 to 100 mesh which comprises the following steps: a. holding said beads in a feed chute for at least 1 minute, b. feeding said beads to a screening zone equipped with at least one screen having openings of the desired size and having at least its surface composed of a fluorinated hydrocarbon having a dielectric constant in the range of about 2 to 3, by means of an opening in said feed chute adjacent one of said screens, c. passing said beads across the upper surface of said screen; and d. passing a portion of said beads having a particle size less than 35 mesh through said openings. 6. The method of claim 5 wherein said screen has at least its surface composed of a fluorinated hydrocarbon consisting of poly (chlorotrifluoroethylene), fluorinated ethylene-propylene copolymer or poly (tetrafluoroethylene).
Claim 5
Independent Claim
156 words
A method for classifying dry, substantially spherical polystyrene beads having an average particle size in the range from about 10 to 100 mesh which comprises the following steps: a. holding said beads in a feed chute for at least 1 minute, b. feeding said polystyrene beads to a screening zone equipped with a fine mesh screen coated with poly (tetrafluoroethylene) and having openings in the range between about 35 and 60 U.S. Standard mesh and a coarse meSh screen having openings of about 20 U.S. Standard mesh by means of an opening in said feed chute immediately adjacent said fine mesh screen; c. passing said beads across the upper surface of said fine mesh screen; d. passing a portion of said beads through said openings in said fine mesh screen; e. passing the remaining portion of said beads onto said coarse mesh screen; and f. recovering a portion of said beads through said coarse mesh screen.
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) | 1974-11-15 | 1975-05-17 | 1975-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-15 | 1979-05-17 | 1979-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-15 | 1983-05-17 | 1983-11-16 | $7700.00 | Window Closed / Lapsed |