Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Patent
1994-11-16
1996-04-02
Acquah, Samuel A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
521 40, 5283081, 5283082, 5283084, 5283086, 528481, 528495, 528499, 528503, 210767, 210772, 210908, C08J 1104
Patent
active
055041213
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates a method for the decontamination of poly ethylene terephthalate ("PET").
BACKGROUND OF THE INVENTION
PET is a thermoplastic polyester that can be formed from 1,2-dihydroxyethane ("ethanediol") and terephthalic acid by direct esterification to form bis (hydroxy ethyl) terephthalate ester ("BHT") which is then polymerised by catalysed ester exchange to useful polymers.
Traditionally, PET has been used extensively because it can be offered as an oriented film or fibre, has high tenacity, good electrical resistance and low moisture absorption together with a melting point of approximately 265 degrees Celsius.
For these reasons, its uses have been very diverse extending from being blended with cotton for wash and wear fabrics, blended with wool for worsteds and suitings, packaging films and recording tapes and containers including soft drink containers.
There are a number of applications of PET where remelting and reforming is not permissible or gives inferior properties. The reuse of PET for these applications is best achieved by degrading the polymer into the original monomers namely ethanediol and terephthalic acid then reacting the monomers together to regenerate the original PET.
The known art (British Patent No. 610135) is to hydrolyse PET with either strong alkalis or acids. The alkalis must be neutralised with acid to produce terephthalic acid resulting in a significant cost of reagents and possible contamination of the product with alkali metal ions. The strong acids must be recovered and the ethanediol separated. Further the acids dissolve paper and pigments to give by products which are difficult to separate.
It is known that PET will transesterify with ethanediol (British Patent No. 610136) but the product BHT, is not a convenient intermediate for subsequent purification to remove esters of contaminant acids such as benzoic and adipic acid.
Accordingly, the present invention is directed to an improved process of decontaminating PET.
DESCRIPTION OF THE INVENTION
Accordingly, in one form of this invention, there is provided a process for removing contaminants from PET components by depolymerising PET comprising the following steps: a temperature at or about the boiling point of ethanediol with the material for a predetermined period of time to form a solution containing soluble short chain PET polymers and/or BHT; elevated pressure and temperature for a predetermined period of time to form an ethanediol solution and crystals of terephthalic acid.
According to another form of the invention, there is provided a process for removing contaminants from PET components by depolymerising PET comprising the following steps: temperature at or about the boiling point of ethanediol with the material for a predetermined period of time to form mixture containing embrittled PET; material which contains PET; at or about the boiling point of ethanediol, with the recovered PET for a predetermined period of time to form a solution containing soluble short chain PET polymers and/or BHT; elevated pressure and temperature for a predetermined period of time to form an ethanediol solution and crystals of terephthalic acid.
According to yet another form of the invention, there is provided a process for removing contaminants from PET components by depolymerising PET comprising the following steps: having a temperature at or about the boiling point of ethanediol with the material for a predetermined period of time to form a mixture containing embrittled PET; material containing PET; for a predetermined period of time to form an ethanediol solution and crystals of terephthalic acid; to form short chain PET polymers and/or BHT; and
It has been surprisingly found that ethanediol at or near its boiling point reacts with PET but does not react significantly with products often used in PET containing products including paper, other plastics (for example, poly vinyl chloride ("PVC"), colouring dyes, pigments, mineral sands or clays ("Contaminants").
Typically the step or steps involv
REFERENCES:
patent: 3257335 (1966-06-01), Whitfield, Jr. et al.
patent: 3703488 (1972-11-01), Morton
patent: 3776945 (1973-12-01), Ligorati et al.
patent: 3814786 (1974-06-01), Gull et al.
patent: 3884850 (1975-05-01), Ostrowski
patent: 3907868 (1975-09-01), Currie et al.
patent: 4360661 (1982-11-01), Horlbeck et al.
patent: 4620032 (1986-10-01), Doerr
patent: 5073203 (1991-12-01), Al-Ghatta
patent: 5101064 (1992-03-01), Dupont et al.
patent: 5298530 (1994-03-01), Gamble et al.
Golovoy, "Hydrolysis of 1,4-Cyclohexanedimethanol-based Copolyester," Polymer Engineering and Science, 29(16), 1103-1106 (Aug. 1989).
Masi et al., "Tensile Behavior of High-Density Thermosetting Polyester Foams," Polymer Engineering and Science, 24(7), 469-472 (May 1984).
Chapter 15, "Polyester Resins (Saturated)" in Polymer Manufacturing--Technology and Health Effects, (Radiant Corporation, Noyes Data Corporation), 320-340 (1986).
"Polyester Fibres," pp. 64-65, 72-73, 82-84 (publication details unknown).
"Scrap Recovery," pp. 167-172 (publication details unknown).
"Raw Materials Manufacture and Purification," pp. 30-36 (publication details unknown).
"Polycondensation," pp 159-162 (publication details unknown).
"Heats of Mixing," pp. 1417-1418 (publication details unknown).
"Saturated Polyesters," pp. 200-223, 356-369, 530-541 (publication details unknown).
Acquah Samuel A.
Swig Pty Ltd.
LandOfFree
Polyethylene terephthalate decontamination does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyethylene terephthalate decontamination, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyethylene terephthalate decontamination will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2016695