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US5134291A
Expired / Lapsed
US
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Method for sorting used plastic containers and the like
Assignee: Dow Chemical Co
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Filing: 1991-04-30
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Granted: 1992-07-28
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Expires: 2011-04-30
Abstract
Abstract A method for sorting a plurality of diverse objects into groups, each such object being made predominately from at least polyethylene terephthalate and polystyrene and at least two of polyvinyl chloride, polyethylene and polypropylene, the groups consisting at least of objects of like type of polymer identified to be polyethylene terephthalate and polystyrene and at least two of polyvinyl chloride, polyethylene and polypropylene. The method includes three steps. The first step is to irradiate the objects to be sorted with near-infrared radiation. The second step is to measure the diffuse reflectance of the irradiated objects in the near-infrared region to identify the objects as to the type of polymer used to make them. The third step is to direct the objects to their respective groups according to the measurement and identification of the second step.
Inventors
- 👤 Harry D. Ruhl, Jr.
- 👤 Kenneth R. Beebe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:06
CPC Classifications
B; B07; B07C; B07C5/00; B07C5/34; B07C5/342; G; G01; G01N; G01N21/00; G01N21/17; G01N21/25; G01N21/31; G01N21/35; G01N21/3563; G01N21/359; B29; B29B; B29B17/00; B29B17/02; B29B2017/0213; B29B2017/0279; Y; Y02; Y02W; Y02W30/00; Y02W30/50; Y02W30/62
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
123 words
A method for sorting a plurality of diverse objects into groups, each such object being made predominately from at least polyethylene terephthalate and polystyrene and at least two of polyvinyl chloride, polyethylene and polypropylene, the groups consisting at least of objects of like type of polymer identified to be polyethylene terephthalate and polystyrene and at least two of polyvinyl chloride, polyethylene and polypropylene, the method comprising the steps of: (a) irradiating the objects to be sorted with near-infrared radiation; (b) measuring the diffuse reflectance of the irradiated objects in the near-infrared region to identify the objects as to the type of polymer used to make them; (c) directing the objects to their respective groups according to the measurement and identification of step (b).
Claim 2
Independent Claim
123 words
A method for sorting a plurality of diverse objects into groups, each such object being made predominately from at least polyethylene terephthalate and polystyrene and at least two of polyvinyl chloride, polyethylene and polypropylene, the groups consisting at least of objects of like type of polymer identified to be polyethylene terephthalate and polystyrene and at least two of polyvinyl chloride, polyethylene and polypropylene, the method comprising the steps of: (a) irradiating the objects to be sorted with near-infrared radiation; (b) measuring the diffuse reflectance of the irradiated objects in the near-infrared region to identify the objects as to the type of polymer used to make them; (c) directing the objects to their respective groups according to the measurement and identification of step (b).
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein in step (b) a first derivative is made of a diffuse reflectance spectra of the objects in the near-infrared region.
Claim 4
Dependent Claim
26 words
The method of claim 1 wherein in step (b) a second derivative is made of a diffuse reflectance spectra of the objects in the near-infrared region.
Claim 5
Dependent Claim
30 words
The method of claim 1 wherein in step (b) at least one ratio is made of the diffuse reflectance measurement at at least two different wavelengths in the near-infrared region.
Claim 6
Dependent Claim
29 words
The method of claim 1 wherein in step (b) a diffuse reflectance spectra of the objects in the near-infrared region is positioned in multidimensional space using a digital computer.
Claim 7
Dependent Claim
27 words
The method of claim 1 wherein in step (b) a photodiode array detector is used to measure the diffuse reflectance of the objects in the near-infrared region.
References Cited (Backward Citations)
US3747755A
Cited
US4915827A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-07-28 | 1996-01-27 | 1996-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-07-28 | 2000-01-27 | 2000-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-07-28 | 2004-01-27 | 2004-07-28 | $7700.00 | Window Closed / Lapsed |