GB2528494A

GB2528494A - Recycling process

Info

Publication number: GB2528494A
Application number: GB1413117.1A
Authority: GB
Inventors: Adam Walker
Original assignee: WORN AGAIN FOOTWEAR AND ACCESSORIES Ltd
Current assignee: WORN AGAIN FOOTWEAR AND ACCESSORIES Ltd
Priority date: 2014-07-24
Filing date: 2014-07-24
Publication date: 2016-01-27
Anticipated expiration: 2034-07-24
Also published as: GB2528494B; GB201413117D0

Abstract

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. The process comprises (a) contacting the fabric 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. The second temperature is greater than the first temperature when the two solvent systems are the same. A number of solvents are mentioned, including 1,3-dimethyl-2-imidazolinone (DMI).

Description

Recycling Process

Field of Invention

The invention relates to a process for extracting polyester from fahric. In particular, labric compnsmg polyester and one or more dyes.

Background to the Invention

Plastics are versatile materials that have revolutionised many sectors of industry over thc last 50 ycars. 1-lowever, thc high demand for plastics coupled with thcir poor biodegradability has led to large amounts of plastic waste which is not easy to dispose of. often ending up in landfill. Although recycling processes have been adopted to convert, these waste materials into new production materials, there are still many problems associated with plastics recycling.

One particular industry where plastics are prevalent is the textile industry. Polyesters are used extensively in many garments and these articles are regularly replaced creating waste that would ideally he recycled. Polyester fabrics often include additives which complicate the recycling process as these must be separated from the polyester. In particular. polyesters are often modified to include dyes to add colour to labries. Further, it is frequently the case that many diflerent dyes are used to provide different patterns of colour which makes extracting clean polyesters from these garments difficult.

In view of the difficulty with removing additives from polyester containing garments, recycling processes have been developed which separate garments into dilTerent colours and process each particular type of coloured fabric separately. However, this is a very labour intensive process and requires multiple recycling processes to be performed in parallel, each process producing recycled polyester of a single colour.

The demand for colourless polyester (i.e. without any dye) is greater than that for dyed plastics as these materials can he coloured as required, and so if possible colour should be removed.

Accordingly, what is desired is a process for recycling mixtures of dye containing polyester fabrics into usable clear polyester. The invention is intended to solve or at least amehorate this proNem.

Summary of the Invention

There is provided in a first aspect of the invention, a process for extracting polyester from fabric containing one or more dyes comprising the steps of: a) contacting the fabric with a first solvent system to form a mixture: h) 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 second solvent system are the same; and wherein the first andlor second solvent systems are selected from: amides; esters; arenes; heteroarenes; haloalkanes: haloalkenes; cycloaWanes; cyclic ethers; aldehydes; ketones; carbonates; sulfoxides; nitriles; phosphorus containing compounds; ionic liquids or combinations thereof.

The term "solvent system" is intended to mean a homogeneous or heterogeneous combination of one or more solvents. These solvents may or may not be miscible with one another. Typically, homogeneous systems will be used as this removes the need for apparatus to allow extraction of separated solvent layers.

The term "fabric" is intended to mean any material comprising a matrix of woven and/or non-woven fibres. A "polyester fabric" is intended to mean a fabric in which at least one of the fibres contains polyester. Fabrics are included in a range of consumer products, such as furniture, clothing and offeuts created during the clothing manufacturing process, and a great deal of fabric is frequently discarded along with the associated product. As such, the invention allows polyester to be readily extracted from these fabncs in a cost cffectivc manner which would otherwise simply be disposed of akin to conventional waste.

It is often the case that the fabric is clothing. The term "clothing" is intended to encompass all forms of apparel. Most clothing is used regularly and is washed frequently. This typically causes clothing to become damaged and no longer useable more quickly than other products containing fabric. In view of the low cost to manufacture polyester clothing, the expense of conventional recycling techniques and high demand for new clothing (for example from the fashion industry), the established practise in the art is to simp'y dispose ol waste clothing with conventional rubbish although energetic recycling techniques have been used.

The teim "dye" or "dyes" is intended to refer to compounds incorporated into materials, polyester containing fabrics in the present situation, to imbue said materials with a particular colour. In the textile industry, these dyes are typically organic dyes hut some inorganic dyes and salts of organic dyes are also used. However, sonic colouring agents are very insoluble, typically pure inorganic materials such as titania or carbon black. These insoluble materials can often he removed using sinipk filtration techniques as they form precipitates. Therefore, reference in the specification to "dyes" is intended to refer to cheniical colouring agents, typically organic dyes, excluding insoluble coloured matter such as titania or carbon black.

Further, the "dyes" referred to herein are considered to he separate from other additives which do not modify the optical properties of the plastics with which they are combined.

Although the reaction is typically performed under atmospheric pressure, the process can be performed under higher pressures in order to superheat one or both of the first or second solvent systenis. However, this is typically avoided as this usually requires specialised reaction vessels and higher energy conditions which increases the overall cost of the recycbng process.

The term alkyl' is intended to encompass aliphatic, linear and cyclic saturated carbon chains as well as branched saturated carbon chains. Typically, the alkyl groups used in the invention are in the range Ci to Cio. more typically in the range Ci to Cg and even more typically Ci to C5. Thc tcrm aryl' is intended to refcr to an aromatic ring structure. This may include onc or more fused rings and thc ring or rings may each independently be 5-, 6-. 7-, 8-or 9-menibered rings. Typically, the aryl groups will be a single aromatic ring and even more typically. the ring may he a 5-. or 6-memhered ring.

The term alkenyl' is intended to refer to linear or cyclic carbon chains as well as branched carbon chains having at east one unsaturated carbon-carbon double bond.

Typically, the alkenyl groups used in the invention arc in the range Ci to Cio, more typically in the range Ci to Cs and even more typically Ci to Cs. The term alkynyl' is intended to refer to linear or cyclic carbon chains as well as branched carbon chains having at least one unsaturated carbon-carbon triple bond. Typically, the alkynyl groups used in the invention are in the range Ci to Cm, more typically in the range Ci to Cs and even more typically Ci to C5.

The term alkoxy' is intended to mean an alkyl group as defined above, which is bonded via an oxygen atom.

In a first embodiment on the invention the first solvent system and the second solvent are different. This allows each solvent system to be tailored to either one or more of the dyes and to the polyester respectively. According'y, by using two solvent systems, each adapted for dissolving a specific component of the fabrics, the temperature required to extract dye-free polyester can be minirnised.

The first solvent system is selected to dissolve the dyes but not the polyester at the first temperature. Further, the first solvent system is typically selected so that dissolution of the dye can occur at a reasonable rate at low temperature. Complete dissolution of the dye would eventually occur ii the reaction mixture was maintained at room temperaturc. Howcver, this typically takes a long tinic (potentially days) which is often not suitable for commercial recycling. Therefore, it is often the case that the first solvent system is heated to speed up this process. A balance is required between raising the temperature to a level sufficient to dissolve the (lye at an acceptable rate without increasing die temperature so much that (lie polyester becomes soluble in the first solvent system or that the first solvent system is evaporated.

Typically. the first temperature is in the range 70 °C -120°C, more typically 80°C - 110°C or even more typically 90°C -100°C.

In one example, the second solvent system may be heated. This encourages polyester to dissolve in the second solvent system. Usually, the second solvent system is heated to a temperature in the range 50°C to 150°C, or more typically in the range 60°C to 130°C, or even more typically in the range 70°C to 110°C. These temperatures maxirnise the amount and rate of dissolution of polyester whilst minimising the energy required to raise awl sustain the temperature of the solvent system. Once a sufficient quantity of polyester has been dissolved, the solvent system may be separated and can he cooled and extracted to precipitate (lie polyester.

It is usually the case that the first solvent system comprises one or more solvents selected from: ketones, haloaWanes, haloalkenes, arenes, substituted cycloalkanes, esters, carbonates or combinations thereof. Typically, the first solvent system comprises ketones.

The ketones used in the present invention may be linear or cyclic ketones. Typical ketones that are used in the invention are selected from: menthone; fenehone: carvone; acetophcnone; methoxyacetophenone; propiophenonc; butyrophenone; cyclohexyl methyl ketone; cyclopentylcyclopentanone; thujone; valerophenone; henylacetone; benzophenone; acetonaphthone; acetyltetralin; dibenzoylbenzene; alpha-tetralone; bicyclopentanone; bicyclohexanone; or combinations thereof.

Usually, the first solvent system comprises cyclic ketones. Typical examples of cyclic ketones include: pi valone; cyclopentyl methyl ketone; cycloliexanone; cyeloheptanone; cyclopentanone; or combinations thereof These compounds are relatively inexpensive and have boiling points which allow them to be easily separated from dye mixtures without requiring excessively high temperatures.

In particular. the cyclic ketones used in the first solvent may comprise cyclohexanone.

Cyclohexanone has a high boiling point, is relatively inexpensive and is uselul in dissolving many common organic dyes found in fabrics.

The haloalkanes and haloalkenes are typically selected from chloro and/or bromo alkanes and alkenes. It is often the case that the haloalkanes and haloalkenes are selected from: dichloromethane; chloroform; dichloroethane; trichloroethane; tetraehloroethane; dichloroethene; dibromomethane; bromopropane; dibromopropane; or combinations thereof.

Thc arenes are typically substitutcd arcncs and morc typically include alkyl arenes, amino-substituted arenes and substituted heterocyclic arenes. The alkyl arenes are typically selected from: benzene; toluene; xylene; ethylbenzene. Typical amino substituted henzenes include: aniline; N,N-dimethylaniline; N,N-diethylaniline; pyridine; or combinations thereof.

Usually, the substituted cycloalkanes are substituted heterocycloalkanes. Examples ol typical substituted heterocycloalkanes include: tetrahydrofuran: tetrahydrosilvan; tetrahydropyr2m; dimethoxyethane; dioxol2me; anisole; morpholine; or combinations thereof. Cycloalkenes may also be used such as limonene.

Esters used in the invention are typically alkyl esters. The alkyl esters are typically selected from: ethyl acetate; propyl acetate; butyl acetate; isobutyl acetate; tert-butyl acetate; amyl acetate; isoamyl acetate; ethyl propionate; ethyl butyrate; ethyl isobutyrate; propyl propionate; propyl butyrate; butyl butyrate; isobutyl butyrate; butyl isobutyrate; isobutyl isobutyrate; ethyl valerate; propyl valerate; butyl valerate; amyl valerate; or combinations thereof.

Where carbonates are used in the Iirst solvent system, it is typically ihe ease that the carbonates are selected from: dimethyl carbonate: diethyl carbonate: or combinations thereof.

It is often the case that the second solvent system comprises: arnides; heteroarenes; cyclic ethers; aldehydes; ketones; esters; arenes; sulfoxides; nitriles; imidazoliurn compounds; phosphates; or combinations thereol.

Typically, the second solvent system comprises amides. This includes linear and cyclic amides. Typically, linear arnides are selected from: dimethylformamide; diethylformamide: ethyl methylformamide: dipropylformamide; dihutylformamide; dimethylacetarnide; diethylacetamide; dimethylpropionarnide; dimethylbutyrarnide; or combinations thereof.

It is often the case that cychc aniidcs are used and typical examples of cyclic amides are selected from compounds according to any of general Formula I

NNNV Rb

R6 /C\

R R

Formula I wherein R' and R2 are each independently selected from: hydrogen, alkyl. alkenyL alkynyl, aryl or alkoxy groups; R3 to R'2 are each independently sdected from: hydrogen, alkyl, alkcnyl. alkynyl, aryl or alkoxy groups; wherein each of a to c is a carbon atom, wherein the total linear chain length of a-b-c-d-e is in the range 2 to 5 carbons.

The total linear chain length of a-h-c-d-e is often in the range 2 to 4 carbons.

Typically, the total linear chain length of a-b-c-d-e is in the range 2 to 3 carbons, and more typically the total linear chain length of a-b-c-d-e is 2 carbons. So. for instance, in a five membered ring, a and b could arbitrarily be present, and e, d and e arbitrarily absent. Each of a to e are equivalent in terms of possible substituents. and the identifiers a to e and R3 to R'2 allow for the independent substitution of each ring carbon with each of the options for substituent as defined above. Accordingly. the total ring size may be five membered (2 carbons, for instance a and b present and c. d and e absent), six membered (3 carbons, for instance a-c present and d and e absent), seven mernhcrcd (4 carbons, for instance a-d present and c absent) or eight mcmhcred (all of a-c present). However, often the ring will be five or six membered, often five membered. 3 1'

R to R may he alkyl, particularly short chain alkyl such as methyl. ethyl or n-propyl. Often, each carbon will carry only one substituent, so that on each carbon one of the R groups will be H. For instance, R3 may be hydrogen and R4 selected from alkyl, alkenyl, alkynyl, aryl and alkoxy groups. Similar patterns may be found for b S 6 7 8 9 10 11 12 withR andR.cwithR andR,dwithR andR, andewithR andR Often one or more of a-c will have the associated R groups as H, so that not all ring carbon atoms are substituted. For instance, R3 and/or R4 may be selected from alkyl.

alkenyl. alkynyl. aryl and aWoxy hut the others of R5-R'2 maybe 1-I. Having offly one suhstituent (R!= H) on some or all carbon atoms and/or having substituents on some carbon atoms only, ensures that solubility is retained.

Typically, the cyclic amides comprise: N-methyl-2-pynolidinone; N-ethyl-2- pyrrolidinone; N-acetyl-2-pyrrolidinone; dclta-vakrolactam; cpsilon-caprolaetani: N- methyl-epsilon-caprolactam; N-acetyl-epsilon-eaprolactam; N-phenyl-2- pyrrolidinone; N-benzyl-2-pyrrolidinone; 1,3-dirnethyltetrahydro-2-pyrimidone; 1,3- dieihyllelrahydro-2-pyrimidone; 1.3-dimelhyl-2-iniidaiolidinone; 1.3-dieihyl-2-imidaz.olidinone; or combinations thereof.

It is often the case that the second solvent system comprises l,3-dimethyl-2-imidazolidinone (DM1). The inventors have found that DM1 is an especially effective solvent for not only dissolving polyester but also for leaching dyes from polyester fabrics.

Typically, the arenes are substituted arenes, such as alkyl arenes, ailcoxy arenes.

haloalkyl arenes, nitroarenes or combinations thereof. Typical a1ky arenes are selected from: p-cymene; diethylbenzene; trimethythenzene; mesitylene; durene; cumene; propylbenzene; butylbenzene; isobutylbenzene; tcrt-butylbenzene; butyltoluene; amylbenzene; hexylbenzene; tetrahydronaphthalene; 1-methylnaphthalene: diphenylmethane; or combinations thereof Typically alkoxy arenes are selected from: dimethoxybenzene; veratrole; anethole; phenetole; vanillyl butyl ether; 4-(p-methoxyphenyl)-2-butanone; hydroquinone diethyl ether; propyl phenyl ether: hutyl phenyl ether: henzyl methyl ether; henzyl ethyl ether; benzyl propyl cther; benzyl butyl ethcr; diphenyl ether; dibcnzyl ethcr; eugenol methyl ether; isoeugenol methyl ether; methyichavicol; or combinations thereof.

It is often the case that the haloallcyl arenes are selected from: chloroanisole; bromoanisole; diphenychloromethane; I -chloro-2-phenylethane; hentyl bromide; chlorohenzene; dichlorohenzene; chlorotoluene; hromohenzene; iodohenzene; henzyl chloride; or combinations thereof Where nitroarenes are used, it is typically the case that the nitroarene is nitrobenLene.

The heteroarenes used in the invention typica'ly comprise one or more substitutions of a carbon atom with a nitrogen or oxygen atom. Typically only a single substitution is present and also most commonly nitrogen is the substituting element. Typical heteroarenes are selected from: N-acetylmorpholine; N-propionylmorpholine; N-methylformanilide; N-ethylformanilide; N-acctylhoniopiperazinc; acetylpyridine; N,N'-diacetylpiperazine; or combinations thereof.

The cyclic ethers may he selected from: cineoe; apha-pinene oxide; or combinations thereof. Where aldehydes are used, these may he selected from: hcnzaldehyde; anisaldehyde; 2-phenylacetaldehyde; cinnamaldehyde; 2-phenyl-2-butenal; or combinations thereof.

Esters used in the present invention may include: acetyl tributyl citrate; menthyl acetate; lenchyl acetate; horny] acetate; gamma-hutyrolactone; gamnia-valerolactone; gamma-caprolactone; aipha-angelicalactone; alkyl benzoate; methyl bcnzoate; ethyl bcnzoate; propyl benzoatc: isopropyl benzoate: butyl benzoate; isobutyl benzoatc; see-butyl henzoate; tert-butyl benzoate; amyl benzoate; isoamyl benzoate; hexyl benzoate; henzyl acetate; henzyl propionate; henzyl hutyrate; henzyl isohutyrate; henzyl 2-methylbutyrate; benzyl valerate; benzyl benzoate; methyl phenylacetate; methyl cinnamate; ethyl cinnamate; propyl cinnamate; cinnamyl acetate; cinnamyl propionate; phenyl benzoate; anisyl acetate; 2-phenethyl 2-methylbutyrate; methyl salicylate; ethyl salicylate; methyl o-anisate; methyl m-anisate; methyl p-anisate; ethyl anisate; cthylcnc glycol phcnyl ether acetatc; ethylene glycol 2-phcnethyl ether acetate; propylene glycol phenyl ether acetate; propylene glycol benzyl ether acetate; diethylene glycol methyl ether benzoate; diethylene glycol benzyl ether acetate; dipropylene glycol methyl ether acetate: dipropylene glycol ethy' ether acetate; dipropylene glyeol propyl ether acetate; dipropylene glyeol butyl ether acetate; dipropylene glycol phenyl ether acetate; dipropylene glycol henzyl ether acetate; cyclohexyl henzoate; dimethyl phthalate; diethyl phthalate; dipropyl phthalate; dihutyl phthalate; diarnyl phthalate: methyl ethyl phthalate: methyl ethyl phthalate; methyl propyl phthalate; methyl butyl phthalate; dimethyl isophthalate; diethyl isophthalate; dimethyl terephthalate; diethyl terephthalate; dipropyl terephthalate; dibutyl terephthalate; diisopropyl terephthalate; diisobutyl terephthalate; diethylene glycol dihenzoate; dipropylene glycol dihenzoate; trimethyl orthohcnzoate; triethyl orthobenzoatc; or combinations thereof.

Most typically, the esters comprise compounds according to general formulae IV and V: [R19ooAR14 R14kOOR1 Formula V Formula IV wherein R'4 is an aryl group and wherein R'7 to R'9 are each independently selected from hydrogen, alkyl, alkenyl, alkynyl or ary groups; n is an integer in the range I to 8 and mis 3.

The sulfoxides used in the invention may be selected from: dimethylsulfoxide; methyl ethyl sulfoxide; diethylsulfoxide; dipropylsulfoxide; dihutylsulfoxide; diisopropylsulfoxide; diisobutylsulfoxide; tetramethylenesulfoxide; or combinations thereof. Other sulfur containing compounds, other than sulfoxides, that may be employed include: Tetramethylene sulfide; methylsufate; or combinations therof.

Thc nitrilc compounds may be sclectcd from: bcnzonitrilc; phcnylacctonitrilc; cinnamonitrile; or combinations thereof.

Furthermore, the second solvent system may include a phosphorus containing compound selected from: triethyl phosphite; triethyl phosphate; tripropyl phosphate; trihutyl phosphate; dimethylphosphate; hexamethyiphosphoramide; or combinations thereof.

In addition, supercritical carbon dioxide can also serve as a useful second solvent system. The second solvent system may also comprise an ionic liquid. Typically the ionic liquids comprise a compound according to general formula VI R15O _ç3,Rj Formula VI wherein R'5 is an aryl groups and R'6 is selected from hydrogen, alkyl. alkenyl.

alkynyl or aryl groups; and I is an integer in the range I to 3. The ionic liquid may comprise imidazolium cations selected from: 1,3-dimethylimidazolium; l-ethyl-3-methylimidazolium; I -hutyl-3-mcthylimidazolinrn; or combinations thereof. Typical counter ions used with these ionic liquids include acetate and bcnzoate. Other examples of ionic liquids include tris(2-(2-methoxyethoxy)ethyl)amrnoniurn benzoate.

The inventors have found that the above mentioned first and second solvent systems are particular effective at dissolving dyes and polyesters respectively. Without being bound by theory, it is believed that the first solvent system at the first temperature promotes swelling of the polyester which encourages the leaching of dye from the polyester into the first solvent system. The first solvent system can then be removed using conventional filtration processes leaving the uridissolved. dye-free polyester. It is desirable that the polyester does not dissolve in the first solvent system at the first tempcrature.

In a second embodiment of the invention, the first solvent system and the second solvent system are the same. ffi this situation the second temperature is greater than the first temperature. The solvent system is selected so that, at the first temperature, the solvent system dissolves dyes but does not substantially dissolve polyester and at the second temperature. which is higher than the first temperature, the solvent system dissolves polyester. This aflows one solvent system to he used to remove dyes and dissolve the polyester. This simplifies the polyester extraction process.

It is usually the case that the first temperature is in the range 70 °C -120°C, more typically 80°C -110°C or even more typically 90°C -100°C. The second temperature is typically 100'C -200°C, more typically 110°C -180°C and even more typically 120°C -150°C.

In this embodiment, it is often the case that the first and second solvent systems both comprise: amides; heteroarenes; cyclic ethers; aldehydes; ketones; esters; ardnes; sulfoxides; nitriles; irnidazolium compounds; phosphates; or combinations thereof.

Typically, the second solvent system comprises amides. This includes linear and cyclic amides. Typically, hnear aniides are selected from: dimethylformamide; diethylformamide: ethyl methylformamide: dipropylformamide; dibutylformamide; dimethylacetarnide; diethylacetamide; dimethylpropionamide; dimethylbutyrarnide; or combinations thereof.

It is often the case that cyclic arnides are used and typical examples of cyclic arnides are selected from compounds according to any of general Formula I R/\/R12 4-a SRll Rb d-R R6 /C\

R R

FonnWa I wherein R' and R2 are each independently selected from: hydrogen. ailcyl, alkenyl, alkynyl, aryl or alkoxy groups; R3 to R'2 are each independently sdected from: hydrogen, alkyL alkenyl. alkynyl, aryl or alkoxy groups; wherein each of a to e is a carbon atom, wherein the total linear chain length of a-h-c-d-e is in the range 2 to S carbons.

Typically, the total linear chain length of a-h-c-d-e is in the range 2 to 3 carbons, and more typically the total linear chain length of a-b-c-d-e is 2 carbons. So, for instance, in a five membered ring, a and b could arbitrarily be present, and c. d and e arbitrarily absent. Each of a to e are equivalent in terms of possihk substituents. and the identifiers a to e and R3 to R'2 allow for the independent substitution of each ring carbon with each of the options for substituent as defined above. Accordingly, the total ring size may he live membered (2 carbons, !èr instance a and h present and c, d and e absent), six membered (3 carbons, for instance a-c present and d and e absent).

seven membered (4 carbons, for instance a-d present and e absent) or eight membered (all of a-c present). However, often the ring will be five or six membered, often five membered.

R3 to R'2 may be alkyl. particularly short chain alkyl such as methyl, ethyl or n-propyl. Often, each carbon will carry only one substituent, so that on each carbon one ol the R groups will he H. For instance, R3 may he hydrogen and R4 selected from alkyl. alkenyl. alkynyl. aryl and alkoxy groups. Similar patterns may be found for b with R5 and R6. e with R7 and R8. d with R9 and R'°, and e with R" and R'2.

Often one or more of a-c will have the associated R groups as H. so that not all ring carbon atoms are substituted. For instance. R3 and/or R4 may be selected from alkyl, alkenyl, alkynyl, aryl and alkoxy but the others of R5-R'2 may be H. Having only one suhstituent (R!= H) on some or all carbon atoms and/or having suhstituents on some carbon atoms only, ensures that soluhility is retained.

Typically. the cyclic amides comprise: N-methyl-2-pyrrolidinone; N-ethyl-2- pyrrolidinone; N-acetyl-2-pylTolidinone; delta-valerolactam; epsilon-caprolactarn; 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; l,3-diethyl-2-imidaolidinone; or combinations thereof.

It is often the case that the second solvent system comprises l,3-dimethyl-2-imidaz.olidinone (DM1). The inventors have found that DM1 is an especially effective solvent for not only dissolving polyester but also for leaching dyes from polyester fabrics.

Typically. the arenes are substituted arenes. such as alkyl arenes. alkoxy arenes, haloalkyl arenes. nitroarenes or combinations thereof. Typical alkyl arenes are selected from: p-eymene: diethylbenzene: trimethylbenzene: mesitylene; durene; eumenc; propylhcnzcnc; hutylhcnzcnc; isohutylhcnzcnc; tcrt-hutylhcnzene; butyltoluene; amylbenzene; hexylbenzene; tetrahydronaphthalene; 1-methylnaphthalene; diphenylmethane; or combinations thereof.

Typically alkoxy arenes are selected from: dimethoxyhcnzcne; veratrole; anethole; phenetole; vanillyl butyl ether; 4-(p-methoxyphenyl)-2-butanone; hydroquinone diethyl ether; propyl phenyl ether; butyl phenyl ether; benzyl methyl ether; benzyl ethyl ether; benzyl propyl ether; benzyl butyl ether; diphenyl ether; dibenzyl ether; eugenol methyl ether: isoeugenol methy' ether; methylchavicol; or combinations thereof.

It is often the case that the haloalkyl arenes are selected from: chloroanisole; bromoanisole; diphenylchloromethane; I -chloro-2-phenylethane; henzyl bromide; chlorobenzene; dichlorobenzene; chlorotoluene; bromobenzene; iodobenzene; benzyl chloride; or combinations thereof.

Where nitroarenes are used, it is typically the casc that the nitroarenc is nitrohenzene.

The heteroarenes used in the invention typically comprise one or more substitutions of a carbon atom with a nitrogen or oxygen atom. Typically only a single substitution is present and also most commonly nitrogen is the substituting element. Typica' heteroarenes are selected from: N-acetylmorpholine; N-propionylmorpholine; N-methylloimanilide; N-ethylformanilide; N-acetylhomopiperazine; acetylpyridine; N,N'-diacetylpiperazine; or combinations thereof.

The cyclic ethers may be selected from: cineole; alpha-pinene oxide; or combinations thereof. Where aldehydes are used, these may be selected from: benLaldehyde; anisaldehyde; 2-phenylacetaldehyde; cinnamaldehyde; 2-phenyl-2-butenal; or combinations thereof.

Esters used in the present invention may include: acetyl tributyl citrate; menthyl acetate; fenchyl acetate; bornyl acetate; gamma-butyrolactone; gamma-valerolactone; gamma-caprolactone; alpha-angelicalactonc; alkyl benzoate; methyl bcnzoate; ethyl benzoate; propyl benzoate; isopropyl benzoate; butyl benzoate; isobutyl benzoate; sec-hutyl henzoate; tert-hutyl henioate; amyl henioate; isoamyl henioate; hexy henzoate; henzyl acetate; henzyl propionate; benzyl butyrate; benzyl isobutyrate; henzyl 2-methylbutyrate: henzyl valerate; henzyl henzoate; methyl phenylacetate; methyl cinnamate; ethyl cinnamate; propyl cinnamate; cinnamyl acetate; cinnarnyl propionate; phenyl benzoate; anisyl acetate; 2-phenethyl 2-methylbutyrate; methyl salicylatc; ethyl salicylate; methyl o-anisate; methyl m-anisate; methyl p-anisate; ethyl anisate; ethylene glyeol phenyl ether acetate; ethylene glycol 2-phenethyl ether acetate; propylene glycol phenyl ether acetate; propylene gycol henzyl ether acetate; diethylcnc glycol methyl ether benzoate; diethylene glycol benzyl ether acetate; dipropylenc glycol methyl ether acetate: dipropylcne glycol ethyl ether acetate; dipropylene glycol propyl ether acetate; dipropylene glyeol butyl ether acetate; dipropylcnc glycol phcnyl ether acetate; dipropylcnc glycol hcnzyl ether acetate; cyclohexyl benzoate; dimethyl phthalate; diethyl phthalate; dipropyl phthalate; dibutyl phthalate; diamyl phthalate; methyl ethyl phthalate; methyl ethyl phthalate; methyl propyl phthalate; methyl butyl phthalate; dimethyl isophthalate; diethyl isophthalate; di methyl tcrcphthalate: diethyl tcrcphthalatc; dipropyl tcrephthalatc; dihutyl terephthalate; diisopropyl tcrephthalatc; diisobutyl terephthalate; diethylene glycol dibenzoate; dipropylene glycol dibenzoate; tnimethyl orthobenzoate; triethyl orthobenzoate; or combinations thereof.

Most typically, the esters comprise compounds according to general formulae IV and [R19ooAR14 R14OORI9 Formula. V Fonnula IV wherein R'4 is an aryl group and wherein R'7 to R'9 are each independently selected from hydrogen. alkyl, alkenyl. alkynyl or aryl groups; n is an integer in the range 1 to 8 and mis 3.

The sulfoxides used in the invention may he selected from: dimethylsulfoxide; methyl ethyl sulfoxide; diethysulfoxide; dipropylsulfoxide; dihutylsulfoxide; diisopropylsulfoxidc; diisohutylsulfoxidc: tctramcthylcncsulfoxidc: or combinations thereof. Other sulfur containing compounds. other than sulfoxides, that may be employed include: Tetramethylene sulfide; methylsufate; or combinations therof.

The nitrile compounds may be selected from: benzonitrile; phenylacetonitrile; cmnamomtnle; or combinations thereof.

Furthermore, the second solvent system may include a phosphorus containing compound selected from: triethyl phosphite; triethyl phosphate; tripropyl phosphate; trihutyl phosphate; di methyiphosphate; hexamethyiphosphoramide; or combinations thereof.

In addition. supercritical carbon dioxide can also serve as a useful second solvent system. The second solvent system may also comprise an ionic liquid. Typically thc ionic liquids comprisc a compound according to general fommla VI Rb5O r[Q3!=Ri6] Formula I wherein R'5 is an aryl groups and R'6 is selected from hydrogen. alkyl, alkenyl, alkynyl or aryl groups; and I is an integer in the range I to 3. The ionic liquid may comprise imidazolium cations selected from: 1,3-dimethylimidazolium; l-ethyl-3-methylimidazohum; I -hutyl-3-methylimidazolium; or combinations thercof. Typical counter ions used with these ionic liquids include acetate and benzoate. Other examples of ionic liquids include tris(2-(2-methoxyethoxy)ethyl)ammonium benzoate.

It is typicahy the case that the second solvent system at the second temperature dissolves substantially all of the polyester present in the mixture of steps d) and e).

The term substantially aft' is intended to mean greater than 90% of the polyester present in the mixture (br instance 90% -100%). Typically, the second solvent dissolves at least 95% of the polyester, more typically at least 99% of the polyester.

The polyester that is extracted from fabrics is typically selected from: polyglycolic acid (PGA), polylactic acid (PLA). polycaprolactone (PCL). polyethylene aclipate (PEA), polyliydroxyalkanoate (PHA), Polyethykne terephthalate (PET), polyhutykne terephthalate (PBT), polytrirnethylenc terephthalate (PTT), polyethylene naphthalate (PEN) or combination thereof. More typically. the polyester is polyethylene terephthalate (PET). These polyesters are frequently used in the textile industry and arc often difficult to separate from the dyes they are modified with. As such, this makes them commercially very useful to recycle using the present process.

The solvent systems used in the invention may he heterogeneous systems comprising two or more immiscible solvents. In this situation, one of the solvents may he selected to dissolve polyester andlor dyes whilst another solvent or solvents may he selected to dissolve common substances found in the garments being recycled. lii use, the heterogeneous system is typically agitated in order to create a uniform mixture and the garment is exposed to the mixture. After a period of time, the agitation is halted and the solvent system is allowed to separate and one or more of the immiscible solvent phases can be extracted.

Alternatively, the solvent systems used in the invention may be homogeneous systems and the solvent systems may comprise one or more compounds as described above or combinations thereof in an amount in the range 30% to 100% by mass of the total mass of the solvent system. This upper limit of 100%, is intended to mean practically 100%' or 99% or 98%' as, in real world situations, it is never possihk to obtain absolute purity. Typically, the solvent system may comprise one or more compounds described above or combinations thereof in an amount of at least 50% by mass of the total mass of the solvent system. Even more typically. the solvent system may comprise one or more compounds described above or combinations thereof in an amount of at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95% by mass of the total mass of the solvent system so, in the range 50% -100%, 55%-100%, 60%- 100%, 65%-100%. 70%-100%. 75%-100%. 80%-100%. 85%-100%. 90%-100% or 95%-I 00% by mass of the total mass of the solvent system.

Whilst there is no particular restriction on the period of time that a garment is exposed to the solvent systems of the invention, this period may be in the range 30 minutes to 4 hours, more typically in the range 45 minutes to 3 hours, or even more typically in the range 1 to 2 hours. These durations minimise the amount of time required to dissolve a sufficient proportion of the dyes or polyester against the energy required to sustain the temperature of the solvent systems for said period of time.

The process is usually conducted at atmospheric pressure. The process can be conducted under pressurised conditions, in order to achieve superheated a solvent system with higher temperatures than those available at standard pressure and therefore faster rates of reaction. However, this often requires specific reaction chambers capable of withstanding high pressure and intensive heating. This requires a greater input, of energy and does not usually improve the energy efficiency of the process.

Not all colouring agents are readily soube. For example, carbon black is sometimes used to provide a black colour to garments which consists essentially of non-diamond carbon. This and other inorganic materials are insoluble in most solvent systems.

Further, many garments containing a Hend of polyester and other materials (such as cotton) which do not dissolve in the second solvent system. Accordingly, the process may include a filtration step wherein the dissolved polyester is filtered to remove fine particles of inorganic and other insoluble matter.

Once the polyester has been dissolved it is typically extracted from the second solvent system by evaporating the solvent. This can be done using elevated temperatures and/or using vacuum extraction to remove the solvent to leave the dye-free polyester.

It is often the case that the removed second solvent system is condensed and reused in the process. The removed second solvent system may be used either as a source of the first solvent system in step a) and/or as a source of the second solvent system which is used in step d). Typically, and necessarily where the first scAvent system is not the same as the second solvent system, the second solvent is reused as the second solvent system in step d). This reduces the aniount of waste solvent generated in the process and minimises the amount of solvent required for the reaction.

The first solvent system is also typically isolated from the dyes using elevated temperatures and/or vacuum extraction to remove the first solvent system. This can be condensed and reused in the process to further minimise the amount of waste solvent generated by the process. This also isolates the dye materials originally present in the garments which can themselves be reused, for instance in the manufacture of new clothes.

The first solvent system is often recycled and reused as the first solvent system in step a) and/or as the second solvent system used in step d) where the first. and second solvent systems are the same. Typically, the first solvent system is reused as the first solvent system in step a). This recycling of reagents reduces the reliance of the process on new solvent and reduces the amount of solvent consumed.

The invention will now he described with reference to the following figures, drawings

and examples.

Brief Description of the Drawings

Figure 1 shows a schematic diagram of a typical embodiment of the process of the invention wherein the first solvent system and the second solvent system are the same.

Figure 2 shows a schematic diagram of a typical embodiment of the process of the invention wherein the first solvent system and the second solvent system are different.

Description

Figures I 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 "DM1"). Packaging containing polyesters are comminuted and mixed with an excess of DM1 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 DM1 solution is isolated from the polyester mixture in step ii). The dye solution is evaporated under vacuum to separate the DM1 solveni from the dissolved dyes in step vi). The extracted DM1 is then available for recycling into the initial reaction vessel in step vii) or can be incorporated into the reaction mixture in step viii).

The polyester mixture is then reacted with DM1 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 DM1 I polyester mixture from the remaining insoluble impurities. The polyester is then isolated by evaporating the DM1 under vacuum in step v). The evaporated DM1 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).

Figure 2 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 eyelohexanone 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 ffltered and the dye containing cycthhexanone solution is isolated from (lie 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).

The polyester mixture is then reacted with l,3-Dimethyk2-imidazolidinone (DM1) 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 DM1/ polyester mixture from the remaining insoluble impurities. The polyester is the isolated by evaporating the DM1 under vacuum in step v). The evaporated DM1 is condensed and can then be reintroduced into the reaction mixture in step viii).

Examples

Example 1 -Dye removal and subsequent dissolution of post-consumer coloured poly(ethylene terephthalet) (PET) textile in 1,3-dimethyl-2-imidazolidinone (DM1) 1.3-Dimethyl-2-imidazolidinone (DM1, >98%. FChemicals. 1OL) was placed in a 30L glass jacketed reactor with overhead stirrer and condenser and heated to 100°C with stiiTing. Mixcd post-consumer 100% PET textile from shrcddcd garments (500g, rnixturc of white, red, purple, pink, blue. grecn 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 immediatdy and was practically complete alter 10 minutes. The textile was visibly swollen by the solvcnt 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 (1OL) 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 20L Pyrex beaker, where it was allowed to return to room temperature. It was then washed with cold DM1 (5L) and subsequenfly with absolute ethanol (20L) to remove residual solvent.

Claims

Claims I. A process for extracting polyester from fahric containing one or more dyes comprising the steps of: a) contacting the fabne 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 wiih a second solvent system in order to dissolve the pdlyester; e) maintaining the remaining mixture at the second temperature for a second period of time until substantially all of the polyester has been dissolved: 0 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 second solvent system are the same; and wherein the first and/or second solvent systems are selected from: amides; esters; arenes; heteroarenes; haloalkanes; haloalkenes; cycloalkanes; cyclic ethers: aklehydes: kctones; carbonates; sulfoxides; nitriles; ionic liquids; phosphorus containing compounds; or combinations thereof.
2. A process according to claim I, wherein the first solvent system and the second solvent system are different.
3. A process according to claim 2, wherein the first solvent system comprises one or more solvents selected from: ketones. haloalkanes. haloalkenes. arenes, substituted cycloalkanes, esters, carbonates or combinations thereof.
4. A process according to claim 3. wherein the first solvent system comprises ketones.
5. A process according to claim 4, wherein the ketones are cyclic ketones.
6. A process according to claim 5, wherein the cyclic kctoncs comprise: pivalone; cyclopentyl methyl ketone; cyclohexanone; cycloheptanone; cyclopentanone; or combinations thereol.
7. A process according to claim 6. wherein the cyclic ketone comprises cyclohexanone.
8. A process according to claim 3, wherein the haloalkanes and haloalkenes are selected from chioro and/or bromo alkanes and alkenes.
9. A process according to claim 8. wherein the haloalkanes and haloalkenes are selected from: dichioromethane; chloroform: dicifioroethane; trichloroethane; tetrachloroethanc; dichlorocthcnc; dibromomcthanc; bromopropanc; dibromopropanc; or combinations thereof.
10. A process according to claim 3, wherein (lie arenes are sdec(ed from: aWyl arenes; nitroarenes; amino-substituted arenes; substituted heterocyclic arenes; or comhinations thereof.
11. A process according to claim 10, wherein the alkyl arenes are selected from: henzene; toluene; xylene; ethylbenzene.
12. A process according to claim 10, wherein the amino-substituted arenes include: aniline; N.N-dimethylaniline; N,N-diethylaniline; pyridine: or combinations thereof
13. A process according to claim 3. wherein the substituted cycloalkanes are substituted heterocycloalkanes.
14. A process according to claim 13, wherein the substituted heterocycloalkanes are selected from: tetrahydrofuran; (etrahydrosilvan; tetrahydropyran; dime(hoxyethane; dioxolane; ani sole; morpholine; or combinations (hereof.
15. A process according to claim 3, wherein the esters are alkyl esters.
16. A process according to claim 15. wherein the alkyl esters are selected from: ethyl acetate; propyl acetate; butyl acetate; isobutyl acetate; tert-butyl acetate; amyl acetate; isoamyl acetate; ethyl propionate: ethyl hutyrate; ethyl isohutyrate: propyl propionate; propyl butyrate; butyl butyrate; isobutyl butyrate; butyl isobutyrate; isobutyl isobutyrate; ethyl valerate; propyl valerate: butyl valerate; amyl valerate; or combinations thereof.
17. A process according to claim 3. wherein the carbonates are selected from: dimethyl carbonate; diethyl carbonate; or combinations thereol
18. A process according to any preceding claim, wherein the second solvent system comprises: amides; heteroaitncs; cyclic ethers; aldehydes; ketones; esters; arenes; sulfoxides; nitriles; ionic liquids; phosphorus containing compounds; or combinations thereof.
19. A process according to claim 18, wherein the second solvent system comprises amides.
20. A process according to claim 19, wherein amides are selected from: dimethylformarnide; diethylfommrnide; ethylmethylformarnide; dipropylformamide; dibutylformamide; dimethylacetamide; diethylacetamide; dimethylpropionamide; dimethylbutyramide; or combinations thereof.
21. A process according to claim 19, wherein the amides arc cyclic arnidcs.
22. A process according to claim 21, wherein cyclic amides are selected from compounds according to any of general Formula I R/R12 4_-a eRll Rb R6 /C\ 8R RFormula I wherein R' and R2 are each independently selected from: hydrogen, alkyl. alkenyl.alkynyl, aryl or alkoxy groups; R1 to R'2 are each independently selected from: hydrogen, alkyl. alkenyl, aWyny, aryl or alkoxy groups; wherein each of a to e is a carbon atom, wherein the total linear chain length of a-b-c-d-e is in the range 2 to S carbons.
23. A process according to claim 22, wherein the cyclic amides include: N-methyl-2-pyrrolidinone; N-ethyl-2-pylTolidinone; N-acetyl-2-pyrrolidinone; delta-valerolactarn; epsilon-caprolactam; N-methyl-epsilon-caprolactam; N-acetyl-epsilon-caprolactam; N-phenyl-2-pyrrolidinone; N-benzyl-2-pynolidinone; 1,3-dimethyltetrahydro-2-pyrimidonc; 1.3-diethylletrahydro-2-pyrimidone: I,3-dimcthyl-2-imidazolidinonc; 1,3-diethyl-2-irnidazolidinone; or combinations thereof.
24. A process according to claim 23, wherein the second solvent system comprises 1,3-dimcthyl-2-imidazolidinone.
25. A process according to claim 18. wherein the arenes are selected from: a1ky arenes; alkoxy arenes; haloaWyl arenes; or combinations thereof.
26. A process according to claim 25, wherein the alkyl arenes are selected from: p-cymene; diethylbenzene; trimethylbenzene; mesitylene; durene; cumene; propylbcnzcnc; butylbcnzene; isobutylbcnzcne; tcrt-butylbenzenc; butyltoluene; amylbenzene; hexylbenzene; tetrahydronaphthalene; 1 -methylnaphthalene; diphenylmethane; or combinations thereol.
27. A process according to claim 25. wherein the alkoxy arenes are selected from: dimethoxybenzene; veratrole; anethole; phenetole; vanillyl butyl ether; 4-(p-methoxyphenyl)-2-hutanone; hydroquinone diethyl ether; propyl phenyl ether; hutyl phenyl ether; benzyl methyl ether; benzyl ethyl ether; benzyl propyl ether; benzyl butyl ether; diphenyl ether; dibenzyl ether; eugenol methyl ether; isoeugenol methyl ether; methylchavicol; or combinations thereof.
28. A process according to claim 25, wherein the haloalkyl arenes are selected from: chloroanisole; bromoanisole; diphenylchloromethane; 1 -ehloro-2-phenylethane; benzyl bromide; chlorobenzene; diehlorobenzene; ehlorotoluene; bromobenzene; iodohenzene; hentyl chloride; or combinations thereo 1.
29. A process according to claim 18. wherein the heteroarenes comprise one or more substitutions of a carbon atcm with a nitrogen or an oxygen atcm.
30. A process according to claim 29, wherein one carbon atom has been substituted.
31. A process according to claim 29 or 30, wherein the carbon is substituted with a nitrogen atom.
32. A process according to claim 31, wherein the heteroarenes are selected from: N-acetylmorpholine; N-propionylmorpholine; N-methylfoimanilide; N-ethylfoirnanilide; N-acetylhomopiperazine; acetylpyridine; N.N'-diacetylpiperazine; or combinations thereof.
33. A process according to claim 18, wherein the cyclic ethers are sdected from: cineole; aipha-pinene oxide; or combinations thereof.
34. A process according to claim 18, wherein the aldehydes are selected from: benzaldehyde; anisaldehyde; 2-phenylacetaldehyde; einnamaldehyde; 2-phenyl-2-hutenal: or eomhinations thereok
35. A process according to claim 18. whernin the esters are selected from: acetyl tributyl citrate; menthyl acetate; fenchyl acetate; bornyl acetate; gamma-butyrolactone; gamma-valcrolaetone; gamma-caprolaetone; aipha-angelicalactone: alkyl henzoate; methyl benzoate; ethyl benzoate; propyl benzoate; isopropyl benzoate; butyl benzoate; isobutyl benzoate; sec-butyl benzoate; tert-butyl benzoate; amyl benzoate; isoamyl benzoate; hexyl benzoate; benzyl acetate; benzyl propionate; benzyl butyrate; benzyl isohutyrate; henzyl 2-methylhutyrate; henzyl valerate; hcnzyl henzoate; methyl phenylacetate; methyl cinnamate; ethyl cinnamate; propyl cinnamate; cinnamyl acetate; cinnamyl propionate; phenyl benzoate; anisyl acetate; 2-phenethyl 2- methylbutyrate; methyl salicylate; ethyl salicylate; methyl o-anisate; methyl m-anisate; methyl p-anisate; ethyl anisate: ethylene ycol phenyl ether acetate; ethy'ene glycol 2-phenethyl ether acetate; propylene glycol phenyl ether acetate; propylene glycol heniy ether acetate; diethyene glycol methyl ether henzoate; diethylene gycol henzyl elher acetate; dipropylene glycol methyl ether acetate; dipropylene gycol ethyl ether acetate: dipropylene glycol propyl ether acetate; dipropylene glyeol hutyl ether acetate; dipropylene glycol phenyl ether acetate; dipropylene glycol benzyl ether acetate; cyclohexyl benzoate; thmethyl phthalate; diethyl phthalate; dipropyl phthalate; dibutyl phthalate; diamyl phthalate; methyl ethyl phthalate; methyl ethyl phthal ate; methyl propyl phthalate: methy' hutyl phthalate: di methyl i sophthalate; diethyl isophthalate; dimethyl terephthalate; diethyl terephthalate; dipropyl terephthalate; dibutyl terephthalate; dnsopropyl terephthalate; diisobutyl terephthalate; diethylene glycol dibenzoate; dipropylene glycol dibenzoate; trimethyl orthobenzoate; triethyl orthobcnzoate; or combinations thereof.
36. A process according to claim 18, wherein the esters comprise compounds according to general formulae IV and V wherein R'4 is an aryl group and wherein R'7 to are each independently sdected from hydrogen, alkyl. aWeny, alkynyl or aryl groups: n is an integer in the range ito 8 and m is 3.
37. A process according to claim 18, wherein the sulfoxides are selected from: dimcthylsulfoxide: methyl ethyl sulfoxide; diethylsulfoxide: dipropylsulfoxide; dibutylsulfoxide; diisopropylsulfoxide; diisobutylsulfoxide; tetramethylenesulfoxide; or combinations thereof.
38. A process according to claim 18, the nitrile compounds are selected from: bcnzonitrile; phcnylacetonitrilc; cinnamonitnlc; or combinations thereof.
39. A process according to claim 18. wherein the phosphorus containing compounds are selected from: triethyl phosphite; triethyl phosphate; tripropyl phosphate; trihutyl phosphate; dimethylphosphate; hexamethylphosphoramide; or combinations thereof
40. A process according to claim 3, wherein the second soh'ent system comprises an ionic liqnid.
41. A process according to claim 40, wherein comprises a compound according to general formula VI R15O [J3,Rb6J Formula VI wherein R'5 is an aryl groups and R'6 is selected from hydrogen, alkyl. alkenyl.alkynyl or aryl groups; and I is an integer in the range I to 3.
42. A process according to claim 40, wherein the ionic liquid comprises an imidazolium cation.
43. A process according to claim 42, wherein the imidazolium cation is selected from: 1.3-dimethylimidazolium: l-ethyl-3-mcthylimidazolium; 1-butyl-3-methylimidazolium; or combinations thereof
44. A process according to claim 43. wherein the counter ions comprise acetate, benzoate or a combination thereof
45. A process according to claim 40, wherein the ionic liquids comprises tris(2-(2-mcthoxycthoxy)cthyl)ammonium bcnzoate.
46. A process according to claim 1. wherein the first and second solvent systems are the same.
47. A process according to claim 46, wherein the first and second solvent systems comprise: amides; heteroarenes; cyclic ethers; aldehydes; ketones; esters; arenes; sulfoxides; nitrilcs; ionic liquids; phosphorus containing compounds; or combinations thereof.
48. A process according to claim 47, wherein the second solvent system comprises amides.
49. A process according to claim 48. wherein the amides are cyclic amides.
50. A process according to claim 48, wherein ainides are selected from: dimethylformamide; diethylformamide; ethylmethylformamide; dipropylformamide; dihutylformamide; dimethylaeetamide; diethylaeetamide; dimethylpropionamide; dimethyihutyramide; or combinations thereof.
51. A process according to claim 49, wherein cyclic amides are selected from compounds according to any of general Formula I wherein R' and R2 are each independently selected from: hydrogen, alkyl. alkenyl, alkynyl. aryl or alkoxy groups; R3 to R12 are each independently selected from: hydrogen, alkyl, ailcenyl. ailcynyl, aryl or alkoxy groups; wherein each of a to e is a carbon atom, wherein the total linear chain ength of a-b-c-d-e is in the range 2 to S carbons.
52. A process according to claim 49, wherein the cyclic arnides include: N-methyl-2-pyrrolidinone; N-ethyl-2-pyrrolidinone: N-acetyl-2-pyrrolidinone; delta-valerolactam; epsilon-caprolactarn; N-methyl-epsilon-caprolactarn; N-acetyl-epsilon-caprolactam; N-phenyl-2-pyrrolidinone; N-benzyl-2-pynolidinone; l.3-dimethyltetrahydro-2-pyrimidone; 1.3-diethyltetrahydro-2-pyrirnidone; 1.3-dimethyl-2-imidazolidinone; I.3-diethyl-2-i midazolidinone; or combinations thercol
53. A process according to claim 52, wherein the second solvent system comprises 1,3-dimethyl-2-imidazolidinone.
54. A process according to claim 47, wherein the arenes are selected from: alkyl arenes; alkoxy arenes; haloaWyl arenes; or combinations thereof.
55. A process according to claim 54. wherein the ailcyl arenes arc selected from: p-cymene; diethylbenzene; trimethylbenzene; mesitylene; durene; curnene; propylbenzene; but ylbenzene; isobutylbenzene; tert-butylbenzene; butyltoluene; amylbenzene; hexylbenzene; tetrahydronaphthalene; 1 -methylnaphthalene; diphenylmethane; or combinations thereof.
56. A process according to claim 54. wherein the alkoxy arenes are selected from: dimethoxybenzene; veratrole; anethole; phenetole; vanillyl butyl ether; 4-(p-methoxyphcnyl)-2-butanonc; hydroquinone diethyl ether; propyl phenyl ether; butyl phenyl ether; benzyl methyl ether; benzyl ethyl ether; benzyl propyl ether; benzyl hutyl ether; dipheny ether; dihenzyl ether; eugenol methyl ether; isoeugenol methy' ether; methyl chavicol; or combinations thereof.
57. A process according to claim 54. wherein the haloalkyl arenes are selected from: chloroanisole; bromoanisole; diphenylchloromethane; 1 -chloro-2-phenylethane; benzyl bromide; chlorobcnzcnc; dichlorobenzcnc; chlorotolucnc; bromobcnzcnc; iodobenzene; benzyl chloride; or combinations thereof.
58. A process according to claim 47, wherein the heteroarenes comprise one or more substitutions of a carbon atom with a nitrogen or oxygen atom.
59. A process according to claim 58. wherein one carbon atom has been substituted.
60. A process according to claim 58 or 59. wherein the carbon is substituted with a nitrogen atom.
61. A process according to claim 60, whcrcin the hetcroarcncs arc sclcctcd from: N-acetylmorpholine; N-propionylmorpholine; N-methylformanilide; N-ethylformanilide; N-acetylhomopiperazine; acetylpyridine; N,N'-diacetylpiperazine; or combinations thereof.
62. A process according to claim 47. wherein the cyclic ethers are sdeeted from: cineole; aipha-pinene oxide; or combinations thereo 1.
63. A process according to claim 47, wherein the aldehydes are selected from: benzaldehyde; anisaldehyde; 2-phenylacetaldehyde; cinnamaldehyde; 2-Phenyl-2-butenal; or combinations thereof.
64. A process according to claim 47. wherein the esters arc selected from: acctyl tributyl citrate; menthyl acetate; fenchyl acetate; bornyl acetate; gamma-butyrolactone; ganima-valerolactone; gamma-caprolactone; alpha-angelicalactone; ailcyl benzoate; methyl bcnzoatc; ethyl benzoatc; propyl bcnzoatc; isopropyl bcnzoatc; butyl bcnzoatc; isobutyl benzoate; sec-butyl benzoate; tert-butyl benzoate; amyl benzoate; isoarnyl henzoate; hexyl henzoate; benzyl acetate; beniy propionate; henzyl hutyrate; beniy isohutyrate; henzyl 2-methyihutyrate; henzyl valerate; henzyl henzoate; methyl phenylacetate; methyl cinnamate; ethyl cinnamate; propyl cinnarnate: cinnamyl acetate; cinnamyl propionate; phenyl benzoate; anisyl acetate; 2-Phenethyl 2- methylbutyrate; methyl salicylate; ethyl salicylate; methyl o-anisate; methyl m-anisate; methyl p-anisatc; ethyl anisate; ethylene glyeol phenyl ether acetate; ethylene glycol 2-phenethyl ether acetate; propylene glycol phenyl ether acetate; propylene glycol heniy ether acetate; diethyene glycol methyl ether henzoate; diethylene gycol benzyl ether acetate; dipropylene glyeol methyl ether acetate; dipropylene glycol ethyl ether acetate: dipropylene glycol propyl ether acetate: dipropylene glycol butyl ether acetate; dipropylene glycol phenyl ether acetate; dipropylene glycol benzyl ether acetate; cyclohexyl henzoatc; dirnethyl phthalate: diethyl phthalatc; dipropyl phthalate; dibutyl phthalate; diamyl phthalate; methyl ethyl phthalate; methyl ethyl phthalate; methyl propyl phthalate; methyl butyl phthalate; dimethyl isophthalate; diethyl isophthalate; dimethyl terephthalate; diethyl terephthalate; dipropyl terephthalate; dihutyl terephthalate: diisopropy terephthalate; diisohutyl terephthalate; diethylcnc glycol dibenzoate; dipropylene glycol dibenzoate; trimethyl orthobenzoate; tniethyl orthobenzoate; or combinations thereof.
65. A process according to claim 47, wherein the esters comprise compounds according to general formulae IV and V wherein R'4 is an aryl group and wherein R'7 to R'9 are each independently sdected from hydrogen. alkyl. aWenyL alkynyl or aryl groups; n is an integer in the range I to 8 and m is 3.
66. A process according to claim 47, wherein the sulfoxides are selected from: dimethylsulfoxide; methyl ethyl sulfoxide; diethylsulfoxide; dipropylsulfoxide; dibutylsulfoxide; diisopropylsulfoxide; diisobutylsulfoxide; tetramethylenesulfoxide; or combinations thereof
67. A process according to claim 47. the nitrile compounds are selected from: benzonitrile; phenylacetonitrile; cinnamonitrile; nitrobenzene; or combinations thereof.
68. A process according to claim 47, wherein the phosphorus containing compound are selected from: triethyl phosphite; triethyl phosphate; tripropyl phosphate; trihutyl phosphate; dimethyiphosphate: hexaniethyiphosphoramide; or combinations thereof
69. A process according to claim 47, wherein the second solvent system comprises an ionic liquid.
70. A process according to claim 69, wherein comprises a compound according to general formula VI R15O N[)),R16J Fonaula VI wherein R'5 is an aryl groups and R'6 is selected from hydrogen, alkyl, alkenyl.alkynyl or aryl groups; and I is an integer in the range ito 3.
71. A process according to claim 69, wherein the ionic liquid comprises an imidazolium cation.
72. A process according to dairn 71, wherein the imidazolium cation is selected from: 1.3-dirnethylimidazolium; 1 -ethyl-3-methylimidazolium; I -butyl-3-methylimidazolium; or comhinations thereof
73. A process according to claim 71, wherein the counter ions comprises acetate, benzoate or a combination thereof
74. A process according to claim 69, wherein the ionic liquids comprises tris(2-(2-meihoxyelhoxy)elhyl)ammoni urn bentoaie.
75. A process according to any preceding claim, wherein the polyester is selected from: Polyglycolic acid (PGA). Polylactic acid (PLA). Polycaprolactone (PCL).Polyethylene adipate (PEA). Polyliydroxyalkanoate (PHA). Polyethykne terephthalate (PET), Polyhutylene tereplithalate (PBT), Polytrimethyene tercphthalate (PTT), Polyethylene naphthalate (PEN) or combination thereof.
76. A process according to claim 75. wherein the polyester is polyethylene terephthalate.
77. A process according to any preceding claim, wherein the first tempcrature is in the range 70°C -120°C.
78. A process according to claim 77, wherein the first temperature is in the range 90°C -100°C.
79. A process according to any preceding claim, wherein the second temperature is in the range 70°C -200°C.
80. A process according to claim 79, wherein the second temperature is in the range 80°C -150°C.
81. A process according to claim 80. wherein the second temperature is in the range 90°C -100°C.
82. A process according to any preceding claim, wherein the second temperature is greater than the first temperature.
83. A process according to any preceding claim, further comprising the step of recovering the dye from the first scAvcnt system.
84. A process according to claim 83, wherein the first solvent is reused as the first solvent system in step a) and/or wherein the first solvent system is reused as the second solvent in step d).
85. A process according to claim 84. wherein the Iirst solvent is reused as the iirst soh'ent system in step a).
86. A process according to any preceding claim, wherein the second solvent 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).
87. A process according to claim 86. wherein the second solvent is reused as the first solvent system in step d).
88. A process according to any preceding claim, wherein the first and/or the second solvent system are homogeneous.
89. A process according to any preceding claim, wherein the first period of time is in the range 5 minutes to 120 minutes.
90. A process according to claim 89, wherein the first period of time is in the range 5 minutes to 20 minutes.
91. A process according to any preceding claim, further comprising a filtration step to remove undissolved impurities from the second solvent system comprising the dissolved polyester.
92. A process as described in the description, examples and drawings disclosed herein.