Claims
- 1. A process comprising:
- contacting contaminated post consumer polyester with at least one extraction solvent selected from the group consisting of acetone, butanone, ethyl acetate, n-propyl acetate, corn oil and a mixed acid triglyceride of fractionated coconut fatty acids C.sub.8 -C.sub.10, having a fatty acid composition of up to 2% caproic acid (C.sub.6), 50-65% caprylic acid (C.sub.8), 30-45% capric acid (C.sub.10) and up to 3% lauric acid (C.sub.12), at a temperature sufficient to allow rapid diffusion of contaminant from said polyester; and
- separating said extraction solvent containing said contaminants from said polyester to produce a polyester which is suitable for food contact applications.
- 2. The process of claim 1 wherein said temperature is above the glass transition temperature for the polymer solvent mixture.
- 3. The process of claim 1 wherein said contacting and removing steps are repeated until the amount of said contaminant remaining in said polymer is less than about 220 ppb.
- 4. The process of claim 1 wherein said contacting step is conducted in a counter or cross current system.
- 5. The process of claim 4 wherein said system is a continuous countercurrent multistage system or a batch countercurrent multiple stage system.
- 6. The process of claim 1 wherein said extraction solvent is selected from the group consisting of ketones, alcohols, glycol, fatty acid triglycerides, mixtures thereof and mixtures with water.
- 7. The process of claim 1 wherein said extraction solvent is selected from the group consisting of ketones, fatty acid triglycerides, mixtures thereof and mixtures with water.
- 8. The process of claim 1 wherein said polyester is polyethylene terephthalate and said temperature is greater than about 80.degree. C.
- 9. The process of claim 8 wherein said temperature is between about 80.degree. C. and about 125.degree. C.
- 10. The process of claim 1 further comprising extruding and pelletizing said decontaminated polyester flake.
- 11. The process of claim 10 further comprising crystallizing said decontaminated polyester pellets.
- 12. The process of claim 10 further comprising solid-stating said decontaminated polyester pellets to increase molecular weight of said decontaminated polyester pellets.
- 13. The process of claim 10 wherein said extruding step is conducted in a vented extruder wherein residual solvent and/or polycondensation byproducts are removed thereby increasing molecular weight of said polyester flake to a desired level.
- 14. The process of claim 1 further comprising the step of feeding decontaminated polyester flake to melt phase production of polyester material.
- 15. The process of claim 1 wherein said polyester is formed from at least one glycol and at least one aromatic dicarboxylic acid, ester of said aromatic dicarboxylic acid or mixture thereof.
- 16. The process of claim 15 wherein said dicarboxylic acid is selected from the group consisting of terephthalic acid, isophthalic acid; said ester of said aromatic dicarboxylic acid is selected from the group consisting of dimethyl terephthalate and dimethyl isophthalate; and said at least one glycol is selected from the group consisting of ethylene glycol, diethylene glycol, cyclohexane dimethanol and mixtures thereof.
- 17. The process of claim 1 wherein said post consumer polyester is in flake form.
Parent Case Info
This is a continuation of application Ser. No. 08/386,243 filed on Feb. 9, 1995 now abandoned.
US Referenced Citations (10)
Non-Patent Literature Citations (1)
Entry |
Points to Consider for the Use of Recycled Plastics in Food Packaging: Chemistry Considerations, U.S. Food & Drug Administration, May, 1992. |
Continuations (1)
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Number |
Date |
Country |
Parent |
386243 |
Feb 1995 |
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