RECYCLING PROCESS

Abstract

The invention relates to a process for extracting polyester from packaging. In particular, the invention relates to packaging comprising one or more dyes such as black packaging. The claim process uses a two stage extraction process to convert waste polyester in clean, reusable polyester.

The invention relates to a process for extracting polyester from fabric. In particular, fabric comprising polyester and one or more dyes. The claimed process uses a multistage mechanism to separate dyes from polyester containing garments and reconstitute the polyester.

Claims

1. A process for extracting polyester from fabric and/or packaging containing one or more dyes comprising the steps of: a) contacting the fabric and/or packaging with a first solvent system to form a mixture; b) maintaining the mixture at a first temperature for a first period of time until substantially all of the dye has been dissolved; c) removing the first solvent system containing the dissolved dye; d) contacting the remaining mixture with a second solvent system in order to dissolve the polyester; e) maintaining the remaining mixture at the second temperature for a second period of time until substantially all of the polyester has been dissolved; f) removing the second solvent system containing the dissolved polyester; and g) recovering the polyester from the second solvent system; wherein the second temperature is greater than the first temperature when the first solvent system and the second solvent system are the same, and wherein the second dolvant system comprises a cylic amide.

2.-145. (canceled)

146. The process according to claim 1, wherein the first and second solvent systems are the same.

147. The process according to claim 146, wherein the cyclic amide is selected from compounds according to general Formula I ##STR00004## wherein R.sup.1 and R.sup.2 are each independently selected from: hydrogen, alkyl, alkenyl, alkynyl, aryl or alkoxy groups; R.sup.3 to R.sup.12 are each independently selected from: hydrogen, alkyl, alkenyl, alkynyl, aryl or alkoxy groups; wherein each of a to e, if present, is a carbon atom, wherein the total linear chain length of a to e is in the range 2 to 5 carbons.

148. The process according to claim 1, wherein the cyclic amide comprises: N-methyl-2-pyrrolidinone; N-ethyl-2-pyrrolidinone; N-acetyl-2-pyrrolidinone; delta-valerolactam; epsilon-caprolactam; N-methyl-epsilon-caprolactam; N-acetyl-epsilon-caprolactam; N-phenyl-2-pyrrolidinone; N-benzyl-2-pyrrolidinone; 1,3-dimethyltetrahydro-2-pyrimidone; 1,3-diethyltetrahydro-2-pyrimidone; 1,3-dimethyl-2-imidazolidinone; 1,3-diethyl-2-imidazolidinone; or combinations thereof.

149. The process according to claim 148, wherein the cyclic amide comprises 1,3-dimethyl-2-imidazolidinone.

150. The process according to claim 1, wherein the first solvent system and the second solvent system are different.

151. The process according to claim 150, wherein the first solvent system comprises one or more solvents selected from: ketones, haloalkanes, haloalkenes, arenes, substituted cycloalkanes, esters, carbonates or combinations thereof.

152. The process according to claim 150, wherein the cyclic amide is selected from compounds according to general Formula I ##STR00005## wherein R.sup.1 and R.sup.2 are each independently selected from: hydrogen, alkyl, alkenyl, alkynyl, aryl or alkoxy groups; R.sup.3 to R.sup.12 are each independently selected from: hydrogen, alkyl, alkenyl, alkynyl, aryl or alkoxy groups; wherein each of a to e, if present, is a carbon atom, wherein the total linear chain length of a to e is in the range 2 to 5 carbons.

153. The process according to claim 150, wherein the cyclic amide comprises: N-methyl-2-pyrrolidinone; N-ethyl-2-pyrrolidinone; N-acetyl-2-pyrrolidinone; delta-valerolactam; epsilon-caprolactam; N-methyl-epsilon-caprolactam; N-acetyl-epsilon-caprolactam; N-phenyl-2-pyrrolidinone; N-benzyl -2-pyrrolidinone; 1,3-dimethyltetrahydro-2-pyrimidone; 1,3-diethyltetrahydro-2-pyrimidone; 1,3-dimethyl-2-imidazolidinone; 1,3-diethyl-2-imidazolidinone; or combinations thereof.

154. The process according to claim 153, wherein the cyclic amide comprises 1,3-dimethyl-2-imidazolidinone.

155. The process according to claim 1, wherein the polyester is selected from the group consisting of: Polyglycolic acid (PGA), Polylactic acid (PLA), Polycaprolactone (PCL), Polyethylene adipate (PEA), Polyhydroxyalkanoate (PHA), Polyethylene terephthalate (PET), Polybutylene terephthalate (PBT), Polytrimethylene terephthalate (PTT), Polyethylene naphthalate (PEN) and combination thereof.

156. The process according to claim 155, wherein the polyester is polyethylene terephthalate.

157. The process according to claim 1, wherein the second temperature is greater than the first temperature.

158. The process according to claim 1, further comprising the step of recovering the dye from the first solvent system.

159. The process according to claim 1, further comprising repeating steps a) through g).

160. The process according to claim 159, wherein the first solvent system is reused as the first solvent system in step a) and/or wherein the first solvent system is reused as the second solvent system in step d).

161. The process according to claim 160, wherein the first solvent system is reused as the first solvent system in step a).

162. The process according to claim 159, wherein the second solvent system is reused as the first solvent system in step a) and/or wherein the second solvent system is reused as the second solvent system in step d).

163. The process according to claim 162, wherein the second solvent system is reused as the second solvent system in step d).

164. The process according to claim 1, wherein the first and/or second solvent systems are homogeneous.

165. The process according to claim 1, wherein the first period of time is in the range of 5 minutes to 120 minutes.

166. The process according to claim 165, wherein the first period of time is in the range of 5 minutes to 20 minutes.

167. The process according to claim 1, further comprising a filtration step to remove undissolved impurities from the second solvent system comprising the dissolved polyester.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0105] FIGS. 1 and 2 show schematic diagrams of a typical embodiment of the process of the invention wherein the first solvent system and the second solvent system are the same.

[0106] FIGS. 3 and 4 show schematic diagrams of a typical embodiment of the process of the invention wherein the first solvent system and the second solvent system are different.

DESCRIPTION

[0107] FIG. 1 shows an example of the recycling process of the invention, wherein the solvent used for both the dye extraction step and polyester extraction steps is methyl benzoate. Packaging containing polyesters are comminuted and mixed with an excess of methyl benzoate and the reaction mixture is heated to a temperature in the range 90 C. to 100 C. for approximately 10 minutes in step i). The reaction material is then filtered and the dye containing methyl benzoate solution is isolated from the polyester mixture in step ii). The dye solution is evaporated under vacuum to separate the methyl benzoate solvent from the dissolved dyes in step vi). The extracted methyl benzoate is then available for recycling into the initial reaction vessel in step vii) or can be incorporated into the reaction mixture in step viii).

[0108] The polyester mixture is then reacted with methyl benzoate at a temperature of 120 C. to 130 C. for two hours until all at least 95% of the polyester has been dissolved in step iii). The resulting mixture is then filtered in step iv) to separate the methyl benzoate/polyester mixture from the remaining insoluble impurities. The polyester is the isolated by evaporating the methyl benzoate under vacuum in step v). The evaporated methyl benzoate is condensed and can then be reintroduced into the reaction mixture at step vii) or alternatively can be introduced into the reaction mixture at step viii).

[0109] FIG. 2 shows an example of the recycling process of the invention, wherein the solvent used for both the dye extraction step and polyester extraction steps is 1,3-dimethylimidazolidinone (hereafter referred to as DMI). Packaging containing polyesters are comminuted and mixed with an excess of DMI and the reaction mixture is heated to a temperature in the range 90 C. to 100 C. for approximately 10 minutes in step i). The reaction material is then filtered and the dye containing DMI solution is isolated from the polyester mixture in step ii). The dye solution is evaporated under vacuum to separate the DMI solvent from the dissolved dyes in step vi). The extracted DMI is then available for recycling into the initial reaction vessel in step vii) or can be incorporated into the reaction mixture in step viii).

[0110] The polyester mixture is then reacted with DMI at a temperature in the range 120 C. to 130 C. for two hours until all at least 95% of the polyester has been dissolved in step iii). The resulting mixture is then filtered in step iv) to separate the DMI/polyester mixture from the remaining insoluble impurities. The polyester is then isolated by evaporating the DMI under vacuum in step v). The evaporated DMI is condensed and can then be reintroduced into the process in step vii) or alternatively can be introduced into the reaction mixture in step viii).

[0111] FIG. 3 shows an example of the recycling process of the invention wherein the solvent used to extract the dyes is different to the solvent used to extract the polyester from the packaging. Packaging containing polyester are comminuted and mixed with an excess of ethyl acetate and the reaction mixture is heat to a temperature in the range 90 C. to 100 C. for approximately 10 minutes in step i). The reaction material is then filtered and the dye containing ethyl acetate solution is isolated from the polyester mixture in step ii). The dye solution is evaporated under vacuum to separate the ethyl acetate solvent from the dissolved dyes in step vi). The extracted ethyl acetate is then available for recycling into the initial reaction vessel in step vii).

[0112] The polyester mixture is then treated with methyl benzoate at a temperature of 120 C. to 130 C. for two hours until all at least 95% of the polyester has been dissolved in step iii). The resulting mixture is then filtered in step iv) to separate the methyl benzoate/polyester mixture from the remaining insoluble impurities. The polyester is the isolated by evaporating the methyl benzoate under vacuum in step v). The evaporated methyl benzoate is condensed and can then be reintroduced into the reaction mixture in step viii).

[0113] FIG. 4 shows an example of the recycling process of the invention wherein the solvent used to extract the dyes is different to the solvent used to extract the polyester from the garments. Garments containing polyester are comminuted and mixed with an excess of cyclohexanone and the reaction mixture is heated to a temperature in the range 90 C. to 100 C. for approximately 10 minutes in step i). The reaction material is then filtered and the dye containing cyclohexanone solution is isolated from the polyester mixture in step ii). The dye solution is evaporated under vacuum to separate the cyclohexanone solvent from the dissolved dyes in step vi). The extracted cyclohexanone is then available for recycling into the initial reaction vessel in step vii).

[0114] The polyester mixture is then reacted with 1,3-Dimethyl-2-imidazolidinone (DMI) at a temperature of 120 C. to 130 C. for two hours until all at least 95% of the polyester has been dissolved in step iii). The resulting mixture is then filtered in step iv) to separate the DMI/polyester mixture from the remaining insoluble impurities. The polyester is the isolated by evaporating the DMI under vacuum in step v). The evaporated DMI is condensed and can then be reintroduced into the reaction mixture in step viii).

EXAMPLES

Example 1

Dissolution of Bottle Grade poly(ethylene terephthalate) (PET) in ethyl benzoate

[0115] Ethyl benzoate (>99%, Sigma Aldrich, 250 mL) was placed in a 1 litre round bottomed flask equipped with reflux condenser and magnetic stirrer and heated to 120 C. with stirring on a hot plate. Mixed post-consumer PET chip from plastic bottles (10 g, mixture of colourless, blue and green) was added to the solvent and the mixture was stirred for 30 minutes at 120 C. Over this period, the solvent was observed to turn green in colour owing to the leaching of dyestuffs. The PET was heavily permeated and swollen by the solvent but did not dissolve to a significant extent. The mixture was then heated to in the range 180-200 C. for a further 2 hours, with stirring, over which period the solid PET was observed to entirely dissolve, yielding a clear green solution. Heating was discontinued and the solution was allowed to cool to room temperature, whereupon it solidified into a waxy polymer-solvent gel phase of a pale blue-green colour. This material was transferred to a filter funnel and washed with a further 250 mL cold ethyl benzoate. The solid was then triturated with a large excess of cold 50% ethanol to remove solvent and dyestuffs. This yielded a pale greenish filtrate and a damp white semicrystalline solid (14.6 g) which was ground to a powder and dried at room temperature in vacuo over MgSO.sub.4 to yield 9.62 g of white solid.

Example 2

Dye Removal and Subsequent Dissolution of Post-Consumer Coloured poly(ethylene terephthalet) (PET) Textile in 1,3-dimethyl-2-imidazolidinone (DMI)

[0116] 1,3-Dimethyl-2-imidazolidinone (DMI, >98%, FChemicals, 10 L) was placed in a 30 L glass jacketed reactor with overhead stirrer and condenser and heated to 100 C. with stirring. Mixed post-consumer 100% PET textile from shredded garments (500 g, mixture of white, red, purple, pink, blue, green and black) was added to the solvent and the mixture was stirred for 30 minutes at 100 C. Leaching of the dyestuffs into the solvent began immediately and was practically complete after 10 minutes. The textile was visibly swollen by the solvent but did not significantly dissolve, whilst the solvent became opaque and dark purple-black in colour. The hot solvent was then pumped off from the vessel, leaving the remaining textile as an off-white solid. Fresh solvent (10 L) was added to the vessel containing the polymer and heated to 160 C. with stirring for 1 hour, over which period the PET dissolved to give a pale yellow solution. This solution was hot-filtered and decanted into a 20 L Pyrex beaker, where it was allowed to return to room temperature. It was then washed with cold DMI (5 L) and subsequently with absolute ethanol (20 L) to remove residual solvent.