Process for identifying plastics by addition of fluorescent dye

• US 5,201,921 A
• Filed: 09/06/1991
• Issued: 04/13/1993
• Est. Priority Date: 09/14/1990
• Status: Expired due to Fees

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Riess, Reinhard, Claussen, Uwe, Luttermann, Klaus, El Sayed, Aziz
• Primary Examiner(s): CLINGMAN, A
• Application Number:
  US07/756,339
• Time in Patent Office: 585 Days
• Field of Search: 8/506, 8/648, 209/3.3, 209/4, 209/579
• US Class Current: 8/506
• CPC Class Codes: B07C 5/3427 by changing or intensifying the optical properties prior to scanning, e.g. by inducing fluorescence under UV or x-radiation, subjecting the material to a chemical reaction
• CPC Class Codes: B29B 2017/0279 Optical identification, e.g. cameras or spectroscopy
• CPC Class Codes: C08J 11/06 without chemical reactions
• CPC Class Codes: C08K 5/0041 Optical brightening agents, organic pigments
• CPC Class Codes: C08L 23/02 not modified by chemical after-treatment
• CPC Class Codes: C08L 69/00 Compositions of polycarbonates; Compositions of derivatives of polycarbonates
• CPC Class Codes: Y02W 30/62 Plastics recycling; Rubber recycling
• CPC Class Codes: Y10S 209/93 Municipal solid waste sorting

Abstract

Process for rendering a plastic identifiable by adding 5 to 10,000 ppb of a fluorescent marker to the plastic during or after is manufacture.

Claims

1. Process for sorting plastic waste or plastic refuse, wherein plastics which have been rendered identifiable by adding 5 to 10,000 ppb of a fluorescent marker to the plastic during or after the manufacture of the plastic are classified according to each type of plastic based on the fluorescence radiation emitted from the plastic.

2. The process of claim 1, wherein said fluorescent marker comprises at least one fluorescent dye selected from the group consisting of coumarins, perylene dyes, benzanthrones, anthrapyrimidines and anthrapyridones.

3. The process of claim 2, wherein said fluorescent dye is either lipophilic or branch-substituted.

4. The process of claim 1, wherein said fluorescent marker comprises complexes of rare earth metals.

5. The process of claim 4, wherein said complexes of rare earth metals comprise at least one substance selected from the group consisting of Eu complexes and Tb complexes.

6. The process of claim 5, wherein said complexes demonstrate sharply defined emission bands and can be identified by irradiation with a normal lamp.

7. The process of claim 1, wherein the radiation emitted from the plastics is generated by a laser.

8. The process of claim 1, wherein the radiation emitted from the plastic is intercepted by a detector.

9. The process of claim 8, wherein the detector records the radiation emitted from the plastic as a signal and said signal is used for triggering a classifying operation.

10. The process of claim 9, wherein the plastic waste or plastic refuse comprises small particles and said classifying operation comprises electrostatic charging and deflection in an electric field.

11. The process of claim 9, wherein the classifying operation comprises mechanical separation.