Use of a deep eutectic solvent for discolouring at least one coloured textile material and method for discolouring at least one coloured textile material using a deep eutectic solvent

Abstract

The present invention relates to the use of a deep eutectic solvent for discolouring at least one coloured textile material and to a method for discolouring at least one coloured textile material using a deep eutectic solvent.

Description

Use of a deep eutectic solvent for bleaching at least one colored textile material and method for bleaching at least one colored textile material using a deep eutectic solvent

[0001] The present invention relates to the use of a deep eutectic solvent for bleaching at least one colored textile material and to a method for bleaching at least one colored textile material using a deep eutectic solvent.

[0002] The technical field of the invention is in particular that of processes for bleaching textile fibers without degrading them, while allowing the recovery of the dyes.

[0003] Polyester materials such as polyethylene terephthalate (PET) were developed to be the main constituent of fabrics. In 2018, global textile production reached 107 million tons, with an estimated 55.1 million tons of PET fibers. Currently, global PET fiber production exceeds 70 million tons, requires a large amount of non-renewable petroleum, and PET is resistant to biodegradation. It is estimated that by 2050, textile production will consume 300 million tons of petroleum and account for 26% of carbon emissions, an increase of 206% and 1200% from 2015, respectively. Furthermore, the textile industry generates large volumes of waste, making it one of the most polluting industries. However, the large amount of non-degradable textile fiber waste can lead to serious environmental and health problems.In particular, fiber-based products more easily generate micro- and nanoparticles due to their large specific surface area. The long-term accumulation of these synthetic polymer micro- and nanoparticles in the atmosphere and oceans poses a risk to the environment and human health. In addition, textile fibers are usually colored. However, dyes derived from such fibers can also cause serious environmental problems. On the one hand, the dyes used are often toxic, or even classified as CMR (substances). carcinogenic, mutagenic and toxic for reproduction). On the other hand, the structures of synthetic dyes have been designed to be difficult to degrade in order to ensure good color fastness. This raises the problem of both the recycling of textile fibers; and their bleaching and / or the treatment of colored effluents.

[0004] Several chemical and physical methods have been developed for PET recycling. For example, polyester is depolymerized using various chemical processes, particularly glycolysis, and the monomers are then purified. However, this type of process is very expensive and difficult to industrialize. Furthermore, textile recycling has encountered difficulties when processing fabrics made from mixed and colored fibers. During depolymerization, large quantities of dyes, often toxic, are released into the effluent. Cotton is most often ground and then subjected to a bleaching process before weaving new fibers. Mechanical recycling of cotton must be adapted to the color of the original fabric, and this complicates the color weaving of new fibers. The presence of dyes and / or auxiliaries can also accelerate the loss of quality of finished products.As a result, most PET textiles are ultimately landfilled or incinerated at the end of their life; and less than 1% of the fibers used in clothing are recycled for clothing production.

[0005] Furthermore, while technologies are being developed to regenerate single fibers, bleaching rarely allows the dyes to be recovered in their original state. They are often considered contaminants and are then degraded during bleaching. In particular, it is known to bleach PET by oxidation-reduction in an aqueous medium, notably using sodium hydrosulfite, sodium formaldehyde sulfoxylate or sodium hypochlorite. However, these aqueous oxidation-reduction methods destroy the dyes. In addition, they affect the fiber structure and / or their strength, and alter the colorability of the regenerated fibers. In addition, they are a significant source of effluent containing sometimes toxic chemicals, which must subsequently be treated. In particular, the high oxygen content of the wastewater produced can lead to serious environmental pollution.

[0006] Other methods tending to preserve the structure of the dyes have been proposed. For example, patent application CN116289167A describes the bleaching of polyester fibers with a solvent comprising trifluoroacetic acid and water, the water content being 5 to 20% by mass relative to the total mass of the solvent. However, this method is not entirely satisfactory in that it does not allow the fibers to be completely bleached. Furthermore, the method involves the adsorption of the dyes, which requires the use of a significant quantity of solid material (activated carbon and other porous solids) to remove all the dyes. The solid material must be treated in order to be reused, which generates a new colored effluent.

[0007] Emerging processes use ionic liquid / water mixtures. Ionic liquids used for bleaching are mostly prepared from hazardous chemicals, such as strong acids, and the presence of water limits processing temperatures above 100°C at normal pressure conditions. Furthermore, the description of ionic liquids for bleaching is made only for textile materials dyed with disperse dyes. Enzymatic methods are expensive and require very specific conditions for the enzymes to be active, while degrading the dyes. In most cases, water is the bleaching medium, with the disadvantages already mentioned, or else organic, highly volatile and sometimes toxic solvents are used.

[0008] Therefore, there is a need to develop a simple and environmentally friendly bleaching method that allows, on the one hand, the recovery of textile fibers without damaging them, and on the other hand, the recovery of dyes as much as possible.

[0009] The first subject of the invention is the use of a deep eutectic solvent for bleaching a colored textile material, said deep eutectic solvent comprising at least one hydrogen bond donor compound and at least one hydrogen bond acceptor compound different from the hydrogen bond donor compound, at least one of said hydrogen bond donor compound or hydrogen bond acceptor compound being an organic compound and at least one of said hydrogen bond donor compound hydrogen bond(s) or hydrogen bond acceptor compound being a non-ionic compound.

[0010] By using a deep eutectic solvent, the colored textile material can be bleached while avoiding the degradation of said textile material and preserving the properties of the dyes initially present in the colored textile material. Said use thus makes it possible to recycle both the textile material and the dye(s). The deep eutectic solvent is inexpensive, stable, low volatile, liquid in a wide temperature range, has a low environmental impact, is capable of solubilizing both organic and inorganic compounds and has good biodegradability. Furthermore, it is adjustable in that it is capable of being applied to very different compounds (depending on the textile material to be bleached and the dye(s) it contains).

[0011] The deep eutectic solvent

[0012] Deep eutectic solvent (also referred to as DES) is a mixture of two or more compounds for which the eutectic point temperature is lower than that of an ideal mixture, exhibiting significant negative deviations from ideality. The temperature depression is such that the mixture is liquid at operating temperature for a certain composition range. Once the compounds are combined in specific proportions to form a deep eutectic solvent, the melting temperature of the mixture of said compounds is lowered, which allows it to be used under acceptable temperature conditions (i.e. less than or equal to 150°C).

[0013] A deep eutectic solvent is particularly distinguished from an ionic liquid because an ionic liquid corresponds to a single compound.

[0014] The deep eutectic solvent used for bleaching a colored textile material comprises at least one hydrogen bond donor compound and at least one hydrogen bond acceptor compound different from the hydrogen bond donor compound, at least one of said hydrogen bond donor compound or hydrogen bond acceptor compound being an organic compound and at least one of said hydrogen bond donor compound hydrogen bond(s) or hydrogen bond acceptor compound being a non-ionic compound.

[0015] In the invention, the term “organic compound” means a compound comprising one or more carbon atom(s) bonded to one or more hydrogen or halogen atom(s) (i.e. a compound comprising at least one CH or CX bond, X being a halogen). Said organic compound is in particular free of metal(s) and metalloid(s). Said organic compound may comprise one or more heteroatoms chosen from an oxygen atom, a nitrogen atom, and their mixture.

[0016] According to a preferred embodiment of the invention, the hydrogen bond acceptor compound is an organic compound and the hydrogen bond donor compound is an organic compound.

[0017] In the invention, the term “ionic compound” means a compound comprising at least one ionic bond, i.e. a non-covalent bond. The ionic compound may be in the form of a salt such as an ammonium salt, a phosphonium salt, a metal salt (metal halide), or a surfactant.

[0018] The molar ratio of hydrogen bond acceptor compound / hydrogen bond donor compound in the deep eutectic solvent is chosen so as to obtain the properties of a deep eutectic solvent as described above. In other words, outside of this molar ratio, the composition formed by the association of said hydrogen bond acceptor compound and said hydrogen bond donor compound does not form a deep eutectic solvent but a simple mixture of compounds.

[0019] In particular, the molar ratio of hydrogen bond acceptor compound / hydrogen bond donor compound ranges from approximately 1 / 30 to 16 / 1, and preferably from 1 / 7 to 7 / 1. This molar ratio is specific to each mixture of hydrogen bond acceptor compound(s) and hydrogen bond donor compound(s) to form the deep eutectic solvent.

[0020] The deep eutectic solvent preferably consists of hydrogen bond acceptor compound(s) and hydrogen bond donor compound(s).

[0021] According to a particularly preferred embodiment, the deep eutectic solvent consists of one or two acceptor compound(s) of hydrogen bond(s) and one or two hydrogen bond donor compound(s).

[0022] The deep eutectic solvent may comprise at most three hydrogen bond acceptor compound(s) and / or at most three hydrogen bond donor compound(s).

[0023] In the deep eutectic solvent, said at least one hydrogen bond acceptor compound is preferentially different from water and said at least one hydrogen bond donor is preferentially different from water. Water is in particular not part of the hydrogen bond acceptor and hydrogen bond donor compounds of the deep eutectic solvent.

[0024] The deep eutectic solvent may further comprise water as an additive or due to a possible hygroscopic nature of one or more of the compounds of said deep eutectic solvent. The water content may be determined by coulometric titration, or by a spectroscopic method (e.g. infrared).

[0025] In the first case, the deep eutectic solvent has a water content lower than the content of each of the hydrogen bond acceptor(s) and hydrogen bond donor(s) compounds of the deep eutectic solvent.

[0026] In the second case, the deep eutectic solvent comprises at most 5% by mass of water, and preferably at most 3% by mass of water, relative to the total mass of the deep eutectic solvent.

[0027] The hydrogen bond acceptor compound

[0028] The bond acceptor compound preferably has a molar mass ranging from approximately 15 to 1500 g / mol, and particularly preferably ranging from approximately 40 to 650 g / mol.

[0029] The hydrogen bond acceptor compound (respectively each hydrogen bond acceptor compound if there are several) present in the deep eutectic solvent preferably represents at least approximately 3 mol%, particularly preferably at least approximately 5 mol%, more particularly preferably at least approximately 8 mol%, and even more particularly preferably at least approximately 10 mol%, by relative to the total number of moles of compounds forming the deep eutectic solvent.

[0030] The hydrogen bond acceptor compound (respectively each hydrogen bond acceptor compound if there are several) present in the deep eutectic solvent preferably has a boiling point greater than or equal to approximately 1.5 that of water, and particularly preferably greater than approximately 1.5, the boiling point being measured at a saturated vapor pressure of 1 bar (normal boiling point).

[0031] According to a preferred embodiment of the invention, the hydrogen bond acceptor compound(s) (respectively each hydrogen bond acceptor compound(s) if there are several) present in the deep eutectic solvent has any one of the following characteristics: - a melting temperature greater than or equal to approximately 20°C, and particularly preferably greater than approximately 20°C, - a dynamic viscosity greater than or equal to approximately 5 mPa.s, and particularly preferably greater than approximately 5 mPa.s.

[0032] The hydrogen bond acceptor compound may be selected from ammonium salts, phosphonium salts, metal salts, alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, sugars, surfactants, amines, and cyclodextrins.

[0033] Examples of ammonium salts as hydrogen bond acceptor compounds include ammonium sulfonates and ammonium halides, and preferably ammonium tosylates, ammonium bromides and ammonium chlorides, such as decyltrimethylammonium bromide [N10111][Br], dodecyltrimethylammonium bromide [N12111][Br], tetradecyltrimethylammonium bromide [N14111][Br], diethylammonium chloride [N22][Cl], tetraethylammonium bromide [N2222][Br], tetraethylammonium chloride [N2222][Cl], tetraethylammonium tosylate [N2222][TsO], tetrapropylammonium chloride [N3333][Cl], butyltrimethylammonium chloride [N4111][Cl], butyltriethylammonium [N4222][CI], tetrabutylammonium bromide [N4444][Br], tetrabutylammonium chloride [N4444][CI], tetraheptylammonium chloride [N7777][CI], methyltrioctylammonium bromide [N8881][Br], methyltrioctylammonium chloride [N8881][CI], tetraoctylammonium bromide [N8888][Br], tetraoctylammonium chloride [N8888][CI], cholinium bromide [Ch][Br], cholinium chloride [Ch][CI], and phosphocholinium chloride [PCh][CI].

[0034] Examples of phosphonium salts as hydrogen bond acceptor compounds include phosphonium halides, and preferably phosphonium bromides, phosphonium chlorides, and phosphonium iodides, such as tetradecyltrihexylphosphonium chloride [P66614][Cl], [P888]O, allyltriphenyl phosphonium bromide [PPh3AII][Br], benzyltriphenyl phosphonium chloride [PPh3Bz][Cl], methyltriphenyl phosphonium bromide [PPh3Me][Br], tetrabutylphosphonium bromide [P4444][Br], and ethyltriphenylphosphonium iodide. [PPh3Et][I].

[0035] Examples of metal salts as hydrogen bond acceptor compounds include transition metal chlorides such as ZnC , ZrOC , CrCh, and FeCh and alkali and alkaline earth metal carbonates such as potassium carbonate.

[0036] Examples of alcohols as hydrogen bond acceptor compounds include phenols and alcohols (eg - CHOH function) such as carvacrol, borneol, menthol, and thymol.

[0037] In the invention, fatty alcohols are defined as alcohols which comprise at least one linear aliphatic hydrocarbon chain having at least 6 carbon atoms.

[0038] Examples of fatty alcohols as hydrogen bond acceptor compounds include tetradecanol, octanol, decanol, and dodecanol.

[0039] Examples of carboxylic acids as hydrogen bond acceptor compounds include citric acid and malic acid.

[0040] In the invention, fatty acids are defined as carboxylic acids which comprise at least one linear aliphatic hydrocarbon chain having at least 6 carbon atoms.

[0041] Examples of fatty acids as hydrogen bond acceptor compounds include decanoic acid, dodecanoic acid, nonanoic acid, and octanoic acid.

[0042] Examples of amino acids as hydrogen bond acceptor compounds include proline, alanine, betaine, and carnitine.

[0043] Examples of sugars as hydrogen bond acceptor compounds include fructose, glucose, sucrose, and xylose.

[0044] Examples of amines as hydrogen bond acceptor compounds include diethanolamine, tetramethyl guanidine, and ethanolamine.

[0045] Examples of surfactants as hydrogen bond acceptor compounds include octylphenoxypolyethoxyethanol (commonly known under the trade name "triton X-100"), sodium dodecyl sulfate, and sodium l,4-bis-2-ethylhexylsulfosuccinate.

[0046] Examples of cyclodextrins as hydrogen bond acceptor compounds include o- p- and y-cyclodextrins.

[0047] The hydrogen bond donor compound(s)

[0048] The bond donor compound(s) preferably has a molar mass ranging from approximately 15 to 1500 g / mol, and particularly preferably ranging from approximately 40 to 650 g / mol.

[0049] The hydrogen bond donor compound(s) (respectively each hydrogen bond donor compound(s) if there are several) present in the deep eutectic solvent preferably represents at least approximately 3 mol%, particularly preferably at least approximately 5 mol%, more particularly preferably at least approximately 8 mol%, and even more particularly preferably at least approximately 10 mol%, by relative to the total number of moles of compounds forming the deep eutectic solvent.

[0050] The hydrogen bond donor compound (respectively each hydrogen bond donor compound if there are several) present in the deep eutectic solvent preferably has a boiling point greater than or equal to approximately 1.5 that of water, and particularly preferably greater than approximately 1.5, the boiling point being measured at a saturated vapor pressure of 1 bar (normal boiling point).

[0051] According to a preferred embodiment of the invention, the hydrogen bond donor compound(s) (respectively each hydrogen bond donor compound(s) if there are several) present in the deep eutectic solvent has any one of the following characteristics: - a melting temperature greater than or equal to approximately 20°C, and particularly preferably greater than approximately 20°C, - a dynamic viscosity greater than or equal to approximately 5 mPa.s, and particularly preferably greater than approximately 5 mPa.s.

[0052] The hydrogen bond donor compound allows the polarity, hydrophobicity, acidity and viscosity of the deep eutectic solvent to be modulated, and thus to adapt to the type of fabric to be bleached.

[0053] The hydrogen bond donor compound(s) may be selected from ammonium salts, phosphonium salts, metal salts, alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, amides, sugars, and amines.

[0054] Some of the above types of compounds can behave as both hydrogen bond acceptors and hydrogen bond donors depending on the chemical groups they contain.

[0055] Examples of ammonium salts as hydrogen bond donor compounds include ammonium halides, and preferably ammonium chlorides, such as cholinium chloride [Ch][CI], and phosphocholinium chloride [PCh][CI].

[0056] Examples of phosphonium salts as hydrogen bond donor compounds include carboxylates of phosphonium such as tetrabutylphosphonium acetate [P4444][OAc] and tetrabutylphosphonium levulinate [P4444][Lev].

[0057] Examples of metal salts as hydrogen bond donor compounds include transition metal, low metal, and alkaline earth metal chlorides such as MgCI2, SnCI2, Zn(NO3), ZnBr2, ZnCI2, CrCI3, and FeCI3.

[0058] Examples of alcohols as hydrogen bond donor compounds include phenols, primary (-CH2OH functions) and secondary alcohols, and polyols, such as borneol, menthol, thymol, 1,2-butanediol, 1,2-decanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1-butanol, 1-propanol, cyclohexanol, diethylene glycol, D-sorbitol, ethylene glycol, furfuryl alcohol, glycerol, hexafluoroisopropanol, hexanediol, linalool, octanol, polyethylene glycol (eg PEG-200, PEG-400, PEG-600), pentaerythritol, alcohol phenethyl, sobrerol, sorbitol, tetraethylene glycol, triethylene glycol, xylenol, xylitol, 4-chlorophenol, m-cresol, o-cresol, sesamol, phenol, 4-phenylphenol, 4-cyanophenol, and hydroquinone.

[0059] Examples of fatty alcohols as hydrogen bond donor compounds include octanol, decanol, dodecanol, hexadecanol, hexanol, and tetradecanol.

[0060] Examples of carboxylic acids as hydrogen bond donor compounds include citric acid, malic acid, 4-hydroxybenzoic acid, 5-sulfosalicylic acid, acetic acid, acrylic acid, adipic acid, benzoic acid, butyric acid, caffeic acid, cinnamic acid, formic acid, gallic acid, glutaric acid, glycolic acid, itaconic acid, ibuprofen, lactic acid, levulinic acid, malonic acid, mandelic acid, methacrylic acid, oxalic acid, p-aminosalicylic acid, p-coumaric acid, phenylacetic acid, phenylpropionic acid, propanoic acid, p-toluenesulfonic acid, pyruvic acid, suberic acid, succinic acid, tartaric acid, tricarballylic acid, trifluoromethanesulfonic acid, and valeric acid.

[0061] Examples of fatty acids as hydrogen bond donor compounds include decanoic acid, dodecanoic acid, nonanoic acid, octanoic acid, cis-9-octadecenoic acid, heptanoic acid, hexadecanoic acid, hexanoic acid, octadecanoic acid, oleic acid, ricinoleic acid, tetradecanoic acid, and undecenoic acid.

[0062] Examples of amino acids as hydrogen bond donor compounds include proline, alanine, glycine, and serine.

[0063] Examples of sugars as hydrogen bond donor compounds include fructose, glucose, sucrose, xylose, and maltose.

[0064] Examples of amides as hydrogen bond donor compounds include urea, methylurea, acetamide, N,N-dimethylurea, 2,2,2-trifluoroacetamide, thiourea, and lidocaine.

[0065] Examples of amines as hydrogen bond donor compounds include ethanolamine, imidazole, and triethanolamine.

[0066] The deep eutectic solvent

[0067] The deep eutectic solvent preferably comprises an ionic compound as the hydrogen bond acceptor compound and a non-ionic compound as the hydrogen bond donor compound.

[0068] According to this embodiment, the hydrogen bond acceptor(s) may be chosen from ammonium salts, phosphonium salts and metal salts, and preferentially from ammonium salts and phosphonium salts; and the hydrogen bond donor compound may be chosen from alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, amides, sugars, and amines, and preferentially from alcohols, carboxylic acids, and amines.

[0069] According to a particularly preferred embodiment of the invention, the hydrogen bond acceptor / hydrogen bond donor pairs are as follows: - ammonium salt or phosphonium salt / alcohol, - ammonium salt or phosphonium salt / carboxylic acid, - ammonium salt or phosphonium salt / amine, - ammonium or phosphonium / amide salt.

[0070] The deep eutectic solvent is preferably liquid at a temperature greater than or equal to approximately 60°C.

[0071] The textile material

[0072] The textile material is preferably in the form of fibers. In other words, the textile material is preferably a fibrous material.

[0073] The textile material may be one or more fibers, one or more yarns, one or more fabrics, or a mixture thereof.

[0074] Preferably, the textile material comprises (or is made of) polyester, viscose, acrylic, wool, silk, cotton, polyamide (e.g. Nylon), or a mixture thereof.

[0075] The deep eutectic solvent can be chosen according to the type of textile material to be bleached and the type of dyes used to color the textile material. Therefore, it offers great modularity.

[0076] The textile material is dyed (colored) with one or more dyes.

[0077] The dyes are preferably organic dyes. Those skilled in the art know organic dyes which are distinguished from inorganic dyes or pigments in that they have at least one organic part responsible for the coloring. Organic dyes can be either organic molecules or salts composed of an organic anion or cation (coloring organic part) whose charge is compensated by a metal cation such as sodium Na +or by a halide anion such as chloride Cl' respectively. Organic dyes are in fact preferentially made up of an organic chromophore-auxochrome pair, a chromophore being a coloring brick and an auxochrome being a possibly ionizable functionalization. When the organic dye contains one or more ionized auxochrome(s), it is also made up of one or more counter-ions, most often one or more metal cations or halide anions such as sodium cations Na + or chloride anions Cl' respectively. The dyes of the invention may be disperse dyes, vat dyes, reactive dyes, direct dyes, acid dyes, or basic dyes (these are all organic dyes), and preferably disperse dyes, vat dyes, reactive dyes, acid dyes, or basic dyes.

[0078] Reactive dyes are widely used in dyeing cellulosic fabrics, such as cotton or viscose, and fabrics of animal origin such as wool or silk.

[0079] Vat dyes and direct dyes are also used to dye cellulosic textile materials.

[0080] Disperse dyes allow the dyeing of hydrophobic thermoplastic fibers, including nylon, polyester, acrylic, and other synthetic fibers.

[0081] Acid dyes are widely used in dyeing wool, silk, and polyamide fibers.

[0082] Basic dyes are used in dyeing wool, silk, and acrylic fibers.

[0083] The dyes of the invention may be luminescent dyes, such as fluorescent, phosphorescent or chemiluminescent dyes.

[0084] According to a first variant, the textile material comprises cotton or viscose (or is made of cotton and / or viscose) and it is colored with at least one reactive dye or a vat dye or the textile material comprises at least one basic dye.

[0085] According to this first variant, the deep eutectic solvent preferably has a pH ranging from approximately 9 to 13.

[0086] In the invention, the pH of the deep eutectic solvent is measured with a pH indicator paper at ambient conditions (i.e. temperature of 18-25°C, atmospheric pressure).

[0087] According to this first variant, the hydrogen bond acceptor compound is preferably an ammonium salt or a phosphonium salt. The hydrogen bond donor compound is preferably an alcohol such as a polyol, an amine, an amide, or a fatty acid.

[0088] According to a second variant, the textile material comprises polyester or acrylic (or is made of polyester and / or acrylic) and is colored with at least one disperse dye.

[0089] According to this second variant, the deep eutectic solvent preferably has a pH ranging from approximately 2 to 9.

[0090] According to this second variant, the hydrogen bond acceptor compound is preferably a phosphonium salt or an ammonium salt. The hydrogen bond donor compound is preferably an alcohol such as a primary alcohol, a polyol such as a diol, a carboxylic acid, or a fatty acid.

[0091] According to a third variant, the textile material comprises wool, silk, or polyamide (or is made of wool, silk and / or polyamide), and it is colored with at least one acid dye.

[0092] According to this third variant, the deep eutectic solvent preferably has a pH ranging from approximately 2 to 6.

[0093] According to this third variant, the hydrogen bond acceptor compound is preferably a phosphonium salt or an ammonium salt. The hydrogen bond donor is preferably a carboxylic acid, an amino acid, an alcohol such as a polyol, or a sugar.

[0094] The deep eutectic solvent is used as such for the decolorization of the colored textile material. In other words, the decolorization of the colored textile material is not carried out with ingredients other than a deep eutectic solvent. In particular, the decolorization of the colored textile material is not carried out with a composition comprising ingredients other than a deep eutectic solvent (e.g. as defined in paragraph

[0012] ).

[0095] The second subject of the invention is a method for bleaching at least one colored textile material, characterized in that it comprises at least the following steps: i) bringing at least one colored textile material into contact with a deep eutectic solvent to form a resulting composition comprising said colored textile material and said deep eutectic solvent, and ii) heating said resulting composition to a heating temperature ranging from approximately 50 to 150°C, said deep eutectic solvent being as defined in the first subject of the invention.

[0096] The method of the invention is simple, easy to implement, and allows the non-destructive bleaching of the textile material and the dye(s), and in particular the recovery of both the bleached textile material without degradation; and the dye(s) initially present in said colored textile material. The method has a high modularity in that it is possible to adapt the deep eutectic solvent to the nature of the colored textile materials and / or to the nature of the dyes they contain. The recovery of the dyes in the solid state makes it possible to limit potentially polluting effluents and they can be reused for other applications. Furthermore, energy costs are reduced by the thermal properties of the solvents, and by the absence of pressurized equipment for the steps of the process which can rise above 100°C.

[0097] Step i)

[0098] Step i) involves bringing at least one colored textile material into contact with a deep eutectic solvent to form a resulting composition comprising said colored textile material and said deep eutectic solvent.

[0099] The colored textile material is preferably as defined in the first subject of the invention.

[0100] Step i) can be carried out by immersing the colored textile material in the deep eutectic solvent. This allows the entire surface and volume of the textile material to be covered and completely impregnated with the deep eutectic solvent.

[0101] Step i) may be preceded by a step iO) in which the colored textile material is broken down, in particular cut into pieces. This thus promotes the bleaching reaction.

[0102] Step i) is preferably carried out at a temperature ranging from approximately 18°C ​​to 60°C, and more preferably at room temperature (i.e. 18-25°C).

[0103] Step i) is preferably carried out at atmospheric pressure.

[0104] Step i) is preferably carried out with a mass ratio of colored textile material / deep eutectic solvent ranging from approximately 1 / 80 to 1 / 10, and particularly preferably from approximately 1 / 50 to 1 / 10. These value ranges make it possible both to promote bleaching and to avoid excessive solvent consumption for environmental reasons, while having sufficient solvent to wet the fabrics to be bleached.

[0105] At the end of step i), the resulting composition preferably consists of the colored textile material and the deep eutectic solvent.

[0106] The bleaching is preferably carried out in a medium comprising at most 5% by mass of water, and preferably at most 3% by mass of water, relative to the total mass of the medium. In other words, the composition resulting from step i) and implemented in step ii) is preferably free of water or having a very low water content.

[0107] Step ii)

[0108] Step ii) involves heating the resulting composition to a heating temperature ranging from approximately 50 to 150°C.

[0109] Step ii) may be carried out by heating the resulting composition from room temperature (i.e. approximately 18-25°C) to the heating temperature as defined in the invention, then maintaining this heating temperature.

[0110] According to the first variant of the invention, step ii) is preferably carried out at a heating temperature ranging from 50°C to 100°C. [YES] According to the second variant of the invention, step ii) is preferably carried out at a heating temperature ranging from 100°C to 150°C, and particularly preferably from 120°C to 140°C.

[0112] According to the third variant of the invention, step ii) is preferably carried out at a heating temperature ranging from 60°C to 110°C, and particularly preferably from 90°C to 110°C.

[0113] Step ii) can last from approximately 1 hour to 48 hours, and preferably from approximately 1 hour to 10 hours.

[0114] Step ii) is preferably carried out with stirring.

[0115] Step ii) is preferably carried out at atmospheric pressure.

[0116] At the end of step ii), a composition is obtained comprising the bleached textile material and a colored composition (solution of the deep eutectic solvent and the dissolved dye).

[0117] Step iii)

[0118] The method may further comprise a step iii) of separating the bleached textile material. The method of the invention thus makes it possible to recover the textile material and the dyes without degradation.

[0119] The textile material is then recovered in solid state at the end of step iii).

[0120] Step iv)

[0121] The method may further comprise a step iv) of washing, preferably at ambient conditions (i.e. temperature of 18-25°C, atmospheric pressure), the bleached textile material, for example with water or a protic solvent such as a C1-C4 alcohol, and preferably ethanol.

[0122] The textile material is then recovered in solid state at the end of step iv).

[0123] Step iv) may be followed by a step v) of drying the bleached textile material, in particular using any method known to those skilled in the art, more particularly using an oven or in air.

[0124] The method may comprise a step vi) of recovering the dyes, preferably in solid form, in particular using an antisolvent. This may then make it possible to recover the dyes in the solid state.

[0125] The antisolvent may be water, an organic compound, a salt, or one of the hydrogen bond acceptor or hydrogen bond donor compounds initially forming the deep eutectic solvent.

[0126] The anti-solvent allows the dye(s) to precipitate.

[0127] As explained above, the method of the invention can be adapted to any type of textile material and any type of dye with which the textile material is dyed.

[0128] The method according to the second subject of the invention can in particular make it possible to separate different types of textile materials into modifying one or more parameters, for example chosen from temperature and deep eutectic solvent, and their combination.

[0129] The invention thus relates to a method for selectively bleaching a colored textile material MT comprising at least two different types of colored textile fibers FA and FB, said method comprising at least the following steps: i) bringing at least one colored textile material MT comprising FA and FB into contact with a first deep eutectic solvent to form a resulting composition, and ii) heating said resulting composition to a first heating temperature ranging from approximately 50 to 150°C, so as to selectively bleach FA, said first deep eutectic solvent being a deep eutectic solvent as defined in the first subject of the invention, iii) separating the textile material MT comprising bleached FA and colored FB from the resulting composition, i') bringing the textile material MT comprising bleached FA and colored FB into contact with a second deep eutectic solvent to form a resulting composition,and ii') heating said resulting composition to a second heating temperature ranging from approximately 50 to 150°C, so as to decolorize FB, said second deep eutectic solvent being a deep eutectic solvent as defined in the first subject of the invention, iii') separating the textile material comprising decolorized FA and decolorized FB from the resulting composition, it being understood that at least the second eutectic solvent is different from the first eutectic solvent or the second heating temperature is different from the first heating temperature.,

[0130] The MT textile material comprising bleached FA and colored FB can be washed and dried, especially after separation step iii).

[0131] The textile material MT comprising bleached FA and bleached FB can be washed and dried, in particular after the separation step iii').

[0132] The invention thus relates to a process for selectively bleaching at least two different colored textile materials MTA and MTB, said process comprising at least the following steps: i) bringing at least two colored textile materials MTA and MTB into contact with a first deep eutectic solvent to form a resulting composition, and ii) heating said resulting composition to a first heating temperature ranging from approximately 50 to 150°C, so as to selectively bleach MTA, said first deep eutectic solvent being a deep eutectic solvent as defined in the first subject of the invention, iii) optionally separating the bleached MTA textile material and the colored MTB textile material from the resulting composition, i') contacting the colored MTB textile material, optionally mixed with bleached MTA, with a second deep eutectic solvent to form a resulting composition, and ii') heating said resulting composition to a second heating temperature ranging from approximately 50 to 150°C, so as to selectively bleach MTB, said second deep eutectic solvent being a deep eutectic solvent as defined in the first subject of the invention, iii') separating the decolorized MTB textile material, and optionally the MTA textile material, from the resulting composition, it being understood that at least the second eutectic solvent is different from the first eutectic solvent or the second heating temperature is different from the first heating temperature.

[0133] The bleached MTA textile material can be washed and dried, especially after separation step iii).

[0134] The bleached MTB textile material can be washed and dried, especially after separation step iii').

[0135] The present invention is illustrated by the following exemplary embodiments, to which it is however not limited.

[0136] Brief description of the drawings

[0137] The invention is illustrated by the following figures and examples.

[0138] Figure 1 shows the discoloration of several textile materials according to a method according to the invention.

[0139] Figure 2 shows optical microscopy images of the fibers before and after bleaching.

[0140] Figure 3 shows the discoloration of a textile material according to a method according to the invention.

[0141] Figure 4 shows an image of the recovery of a dye in the solid state.

[0142] Figure 5 shows the stability of the dye during bleaching according to a process according to the invention.

[0143] Figure 6 shows the selective bleaching of textile materials according to a method according to the invention.

[0144] Examples

[0145] The raw materials used in the examples are listed below: - textile material MT1: polyester dyed by TAD in orange color, code DO30, - MT2 textile material: green Recyc'Elit polyester, RcE code 3, - MT3 textile material: TAD-dyed polyester in red, code DR167, - MT4 textile material: pink Recyc'Elit polyester, RcE code 4, - MT5 textile material: TAD polyamide scraps, blue in color, code PA-B, - MT6 textile material: TAD polyamide scraps, green color, code PA-V, - MT7 textile material: TAD cotton scraps, green color, Co-V code, - MT8 textile material: viscose and polyester scraps from TAD, dark blue, code V / PES-B, - MT9 textile material: cotton and polyester scraps from TAD, dark grey, code Co / PES-G, - MT10 textile material: TAD-dyed polyester in blue, code DB60, - tetraethylammonium chloride - tetrabutylammonium chloride, - choline chloride, - 1,4-butanediol, - levulinic acid, - ethanolamine.

[0146] Unless otherwise stated, all materials were used as received from the manufacturers, without purification.

[0147] Colorimetry measurements

[0148] Colorimetric measurements were carried out on the textile materials before and after bleaching with a KONICA MINOLTA CM-23d portable spectrophotometer, with a Xenon source, under illuminant D65, a standard observation of 10° and specular reflection included.

[0149] The device was connected to SpectraMagic NX Pro v3.4 software during measurements.

[0150] The color of a reference material (colored textile material before contact with a deep eutectic solvent) and the color of a material obtained at the end of the method of the invention (decolorized textile material after contact with a deep eutectic solvent) were successively measured once for each experiment. The color depth of a colored surface can be estimated from the K / S value resulting from the Kubelka-Munk approximation and obtained by the software. The K / S values ​​associated with each measurement were extracted and their sums were calculated over the wavelength range 400-740 nm in 10 nm intervals. The decolorization rate (%D) was calculated by relative deviation of the K / S values ​​before and after decolorization according to the following equation: %D = 100

[0151] Measurements of UV-Visible absorption of dyes

[0152] UV-Visible spectroscopy measurements were performed for selected examples of textile materials. The measurements were carried out on the resulting compositions after bleaching, comprising the dyes extracted from the textile materials and solubilized in deep eutectic solvents. The absence of degradation was verified by comparing the UV-Visible absorption spectra with those of the respective commercial dyes.

[0153] UV-Visible absorption spectra were measured with a JASCO V-770 spectrophotometer controlled by Spectra Manager software version 2.15.01, over a wavelength range of 350–750 nm, with a measurement step of 1 nm. Two quartz cuvettes with a 1 cm optical path were used as reference and sample cuvettes.

[0154] For each sample, a baseline was first measured by adding the same reference solvent to both cuvettes and measuring the UV-Visible absorption spectrum. The UV-Visible absorption spectra of the samples were then measured by replacing the reference solvent in the sample cuvette with a solution containing the colored sample, diluted with the reference solvent.

[0155] The wavelength in nm of the UV-Visible absorption maximum of the extracted and commercial dyes was read directly from the corresponding spectra. Example 1: Process for bleaching a textile material MT1

[0156] In this example 1, the textile material MT1 is in the form of fabric squares of size 1.5x1.5 cm. It comprises a disperse dye well known under the name Disperse Orange 30 (2-[ / V-(2-cyanoethyl)-4-[(2,6-dichloro-4-nitrophenyl)azo]anilino]ethyl acetate). It has an azo-type chemical structure. 52.04 mg of the textile material MT1 is introduced into a 4 ml container and then 1.56 g of a deep eutectic solvent SI is added to form a resulting composition comprising MT1 immersed in SI. The deep eutectic solvent SI comprises tetrabutylammonium chloride as a hydrogen bond acceptor and 1,4-butanediol as a hydrogen bond donor, with a molar ratio of tetrabutylammonium chloride / 1,4-butanediol of 1 / 3. The solid (MT1) / liquid (SI) mass ratio is 1 / 30.

[0157] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 24 hours.

[0158] The obtained bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. It has a white appearance and the bleaching rate %D is 98.4%.

[0159] The resulting colored composition comprising the deep eutectic solvent SI and the dye extracted from the textile material MT1 is filtered with a polytetrafluoroethylene (PTFE) and glass fiber syringe filter, with a diameter of 13 mm and a pore size of 22 μm. 100 μl of the resulting colored composition are introduced into a 0.5 ml microtube and mixed with 400 μl of distilled water as an anti-solvent. The resulting colored composition / water volume ratio is 1 / 4. The mixture is placed in an ice bath until spontaneous return to room temperature. Precipitation of the dye extracted from the textile material MT1 is observed after 20 h. The mixture is centrifuged at ambient conditions for 1 h 30 min, at 9500 rotations per minute, to separate the liquid (deep eutectic solvent SI and water) and solid (dye extracted from the textile material MT1) phases. The use of an anti-solvent such as water thus allows the recovery of the dye in solid state.

[0160] UV-Visible spectroscopy of the resulting colored composition (dye extracted from the textile material MT1 dissolved in SI)

[0161] A stock solution of the commercial dye Disperse Orange 30 is prepared by solubilizing 0.91 mg of solid dye in 8.99 g (8.1 ml) of dimethyl sulfoxide (DMSO), previously acidified with sulfuric acid to a level of 0.5% by volume of total liquid. The stock solution is diluted by mixing 0.33 g (300 μl) of stock solution with 8.97 g (8.1 ml) of acidified DMSO. The UV-Visible absorption spectrum is measured according to the method described previously, using acidified DMSO as the reference solvent. The wavelength of the UV-Visible absorption maximum of the commercial dye is 428 nm.

[0162] The absence of degradation of the dye extracted from the MT1 textile material is verified by measuring the UV-Visible absorption maximum of the colored solution resulting from the bleaching cycle. 72.6 mg (75 μl) of the resulting filtered colored composition is diluted with 4.50 g (4.1 ml) of acidified DMSO. The dilution mass ratio is 1 / 62.

[0163] The UV-Visible absorption spectrum of the dye extracted from the textile material MT1 is then measured, the reference solvent used being the deep eutectic solvent SI diluted in acidified DMSO at a mass ratio of 1 / 62. The wavelength of the UV-Visible absorption maximum of the dye extracted is 435 nm. This confirms the absence of color degradation during the bleaching process of the invention. Example 2: process for bleaching a textile material MT2

[0164] In this example 2, the textile material MT2 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a green dye of unknown type. Its chemical structure is not known. 63.21 mg of the textile material MT2 is introduced into a 4 ml container and then 1.90 g of a deep eutectic solvent SI as defined in example 1 is added to form a resulting composition comprising MT2 immersed in SI. The solid (MT1) / liquid (SI) mass ratio is 1 / 30.

[0165] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 24 hours.

[0166] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. It has a white appearance and the bleaching rate %D is 95.7%. Example 3: Process for bleaching a textile material MT3

[0167] In this example 3, the textile material MT3 is in the form of fabric squares of size 1.5x1.5 cm. It comprises a disperse dye well known under the name Disperse Red 167:1 (2-[2-acetamido-N-(2-acetyloxyethyl)-4-[(2-chloro-4-nitrophenyl)diazenyl]anilino]ethyl acetate). It has an azo-type chemical structure. 57.50 mg of the textile material MT3 is introduced into a 4 ml container and then 1.73 g of a deep eutectic solvent S2 is added to form a resulting composition comprising MT3 immersed in S2. The deep eutectic solvent S2 comprises tetraethylammonium chloride as a hydrogen bond acceptor and 1,4-butanediol as a hydrogen bond donor, with a molar ratio of tetraethylammonium chloride / 1,4-butanediol of 1 / 2. The solid (MT3) / liquid (S2) mass ratio is 1 / 30.

[0168] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 19 hours. It has a pink appearance and the discoloration rate %D is 96.9%.

[0169] A new bleaching cycle is carried out with the obtained pink textile material (56.74 mg) and 1.70 g of a deep eutectic solvent S2 as defined above. The solid (decolorized MT3) / liquid (S2) mass ratio is 1 / 30.

[0170] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 21 hours.

[0171] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. The bleaching rate %D is 99.2%. Example 4: Process for bleaching a textile material MT4

[0172] In this example 4, the textile material MT4 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a pink dye of unknown type. Its chemical structure is not known. 63.04 mg of the textile material MT4 is introduced into a 4 ml container and then 1.89 g of a deep eutectic solvent S2 as defined in example 3 is added to form a resulting composition comprising MT4 immersed in S2. The solid (MT4) / liquid (S2) mass ratio is 1 / 30.

[0173] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 19 hours. It has a white appearance.

[0174] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 5: Process for bleaching a textile material MT3

[0175] In this example 5, the textile material MT3 is in the form of fabric squares of size 1.5x1.5 cm. It comprises a disperse dye well known under the name Disperse Red 167:1 (2-[2-acetamido-N-(2-acetyloxyethyl)-4-[(2-chloro-4-nitrophenyl)diazenyl]anilino]ethyl acetate). Its chemical structure is of the azo type. 59.78 mg of the textile material MT3 is introduced into a 4 ml container and then 1.80 g of a deep eutectic solvent S3 is added to form a resulting composition comprising MT3 immersed in S3. The deep eutectic solvent S3 comprises choline chloride as a hydrogen bond acceptor and levulinic acid as a hydrogen bond donor with a choline chloride / levulinic acid molar ratio of 1 / 2. The solid (MT3) / liquid (S3) mass ratio is 1 / 30.

[0176] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 21h30. It has a white appearance and the discoloration rate %D is 97.5%.

[0177] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 6: Process for bleaching a textile material MT5

[0178] In this example 6, the textile material MT5 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a mixture of acid dyes. The chemical structures are of the anionic, azo and anthaquinone type. 81.53 mg of the textile material MT5 is introduced into a 4 ml container and then 2.45 g of a deep eutectic solvent S3 as defined in example 5 is added to form a resulting composition comprising MT5 immersed in S3. The solid (MT5) / liquid (S3) mass ratio is 1 / 30.

[0179] The resulting composition is heated to 100°C with stirring (rotation at 100 revolutions per minute) for 3 hours 30 minutes. It has a white appearance.

[0180] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 7: Process for bleaching a textile material MT6

[0181] In this example 7, the textile material MT6 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a mixture of acid dyes. The chemical structures are of the anionic, azo and anthaquinone type. 86.05 mg of the textile material MT6 is introduced into a 4 ml container and then 2.58 g of a deep eutectic solvent S3 as defined in example 5 is added to form a resulting composition comprising MT6 immersed in S3. The solid (MT6) / liquid (S3) mass ratio is 1 / 30.

[0182] The resulting composition is heated to 100°C with stirring (rotation at 100 revolutions per minute) for 6 hours. It has a white appearance.

[0183] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 8: Process for bleaching a textile material MT7

[0184] In this example 8, the textile material MT7 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a mixture of reactive dyes. The chemical structures are anionic, azo, double azo, and anthaquinone. 66.87 mg of the textile material MT7 is introduced into a 4 ml container and then 2.02 g of a deep eutectic solvent S4 is added to form a resulting composition comprising MT7 immersed in S4. The deep eutectic solvent S4 comprises choline chloride as a hydrogen bond acceptor and ethanolamine as a hydrogen bond donor with a choline chloride / ethanolamine molar ratio of 1 / 6. The solid (MT7) / liquid (S4) mass ratio is 1 / 30.

[0185] The resulting composition is heated at 80°C with stirring (rotation at 100 revolutions per minute) for 16 hours. It has a white appearance and the discoloration rate %D is 95.4%.

[0186] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 9: Process for bleaching a textile material MT8

[0187] In this example 9, the textile material MT8 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a mixture of reactive dyes for viscose and disperse dyes for polyester. The chemical structures are anionic, double azo, and anthaquinone for viscose and azo for polyester. 82.63 mg of the textile material MT8 is introduced into a 4 ml container and then 2.46 g of a deep eutectic solvent S4 as defined in example 8 is added to form a resulting composition comprising MT8 immersed in S4. The solid (MT8) / liquid (S4) mass ratio is 1 / 30.

[0188] The resulting composition is heated to 80°C with stirring (rotation at 100 revolutions per minute) for 16 hours. It has a white appearance. The polyester is dissolved and the viscose intact. The discoloration rate %D is 96.2%.

[0189] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 10: Process for bleaching a textile material MT9

[0190] In this example 10, the textile material MT9 is in the form of fabric squares of size 1.5x1.5 cm. It comprises a mixture of vat dyes for cotton and disperse dyes for polyester. The chemical structures are anthaquinone type for cotton and azo for polyester. 74.83 mg of the textile material MT9 is introduced into a 4 ml container and then 2.24 g of a deep eutectic solvent S4 as defined in example 8 is added to form a resulting composition comprising MT9 immersed in S4. The solid (MT9) / liquid (S4) mass ratio is 1 / 30.

[0191] The resulting composition is heated to 80°C with stirring (rotation at 100 revolutions per minute) for 16 hours. It has a white appearance. The polyester is dissolved and the cotton intact. The discoloration rate %D is 96.8%.

[0192] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. Example 11 of characterization of discolored textile materials of examples 1-10

[0193] Figure 1 shows: - the MT1 textile material before discoloration then after discoloration (figure 1a), - the MT2 textile material before discoloration then after discoloration (figure lb), - the MT3 textile material before discoloration then after discoloration (figure 1c), - the MT4 textile material before discoloration then after discoloration (figure 1d), - the MT3 textile material before discoloration then after discoloration (figure 1c), - the MT5 textile material before discoloration then after discoloration (figure lf), - the MT6 textile material before discoloration then after discoloration (figure lg), - the MT7 textile material before discoloration then after discoloration (figure lh), - the MT8 textile material before discoloration then after discoloration (figure 11), - the MT9 textile material before discoloration then after discoloration (figure lj).

[0194] Figure 2 shows images with a Leica DM 2500M optical microscope, in unpolarized light by placing some fibers of the textile materials on a glass slide and glued with ethanol then covered with a coverslip. The objective has a magnification of 10x.

[0195] Figure 2 represents in particular: - the MT1 textile material before discoloration (figure 2a) then after discoloration (figure 2b), - the MT6 textile material before discoloration (figure 2c) then after discoloration (figure 2d), and - the MT7 textile material before discoloration (figure 2e) then after discoloration (figure 2f).

[0196] Figure 2 shows that textile materials are intact after discoloration. Example 12: Process for bleaching a textile material MT10

[0197] In this example 12, the textile material MT10 is in the form of fabric squares of dimension 1.5x1.5 cm. It comprises a disperse dye well known under the name Disperse Blue 60 (4,11-diamino-2-(3-methoxypropyl)naphtho[2,3-f]isoindole-1,3,5,10-tetrone). It has an anthraquinone type chemical structure. 65.17 mg of the textile material MT10 is introduced into a 4 ml container and then 1.95 g of a deep eutectic solvent SI as defined in example 1 is added to form a resulting composition comprising MT10 immersed in SI. The solid (MT10) / liquid (SI) mass ratio is 1 / 30.

[0198] The resulting composition is heated at 130°C with stirring (rotation at 100 rpm) for 19 hours. The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. It has a blue appearance and the bleaching rate %D is 84.3%.

[0199] A new bleaching cycle is carried out with the obtained blue textile material (63.89 mg) and 1.93 g of a deep eutectic solvent SI as defined in Example 1. The solid (decolorized MT10) / liquid (SI) mass ratio is 1 / 30.

[0200] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 20 hours.

[0201] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. The bleaching rate %D is 96.7%.

[0202] Figure 3 shows the MT10 textile material before bleaching (Figure 3a) and then after bleaching (Figure 3b).

[0203] Recovery of the dye in the solid state

[0204] The resulting colored composition comprising the deep eutectic solvent SI and the dye extracted from the textile material MT10 obtained after the first bleaching cycle is filtered with a syringe filter made of polytetrafluoroethylene (PTFE) and glass fibers, with a diameter of 13 mm and a pore size of 22 μm. 131 mg of the resulting colored composition is introduced into a 0.5 mL microtube and mixed with 254 mg of distilled water as an anti-solvent. The mass ratio of the resulting colored composition to water is 1 / 2. Precipitation of the dye extracted from the textile material MT10 is observed after a maximum of 48 h. The mixture is left for sedimentation.

[0205] Figure 4 shows an image of the recovery of Disperse Blue 60 dye in the solid state (precipitation).

[0206] UV-Visible spectroscopy of the resulting colored composition (dye extracted from MT10 textile material dissolved in SI)

[0207] A stock solution of the commercial dye Disperse Blue 60 is prepared by solubilizing 3.13 mg of solid dye in 9.99 g (9 ml) of dimethyl sulfoxide (DMSO), previously acidified with sulfuric acid to a level of 0.5% by volume of total liquid. The stock solution is diluted by mixing 0.22 g (200 μl) of stock solution with 9.99 g (9 ml) of acidified DMSO. The UV-Visible absorption spectrum is measured according to the method described previously, using acidified DMSO as the reference solvent. The wavelength of the UV-Visible absorption maximum of the commercial dye is 680 nm.

[0208] The absence of degradation of the dye extracted from the MT10 textile material is verified by measuring the UV-Visible absorption maximum of the resulting colored composition obtained after the first bleaching cycle. 0.20 g (200 μl) of the filtered resulting colored composition is diluted with 9.98 g (9 ml) of acidified DMSO. The dilution mass ratio is 1 / 50.

[0209] The UV-Visible absorption spectrum of the dye extracted from the MT10 textile material is then measured, the reference solvent used being the deep eutectic solvent SI diluted in acidified DMSO at a mass ratio of 1 / 50. The wavelength of the UV-Visible absorption maximum of the dye extracted from the MT10 textile material is 676 nm, which confirms the absence of color degradation.

[0210] Figure 5 shows a UV-visible absorption spectrum of the commercial dye Disperse Blue 60 (solid curve) and of the resulting colored composition after bleaching using a process according to the invention (dotted curve). These curves show the stability of the dye during the bleaching process according to the invention (absence of degradation). Example 13: process for selective bleaching of textile materials MT11, MT12, MT13, MT14

[0211] In this example 13, selective discoloration of polyester was verified on fabrics composed of cotton or viscose blended with polyester.

[0212] Textile material MT11 is a two-sided cotton / polyester mixed fabric from production scraps of the “TAD” dyehouse. It is in the form of fabric squares measuring 1.5x1.5 cm. It contains a mixture of unknown disperse / reactive dyes with azo / anthraquinone chemical structures. Textile material MT12 is a two-sided cotton / polyester mixed fabric from production scraps of the “TAD” dyehouse. It is in the form of fabric squares measuring 1.5x1.5 cm. It contains a mixture of unknown disperse / vat dyes with azo / anthraquinone chemical structures. Textile material MT13 is a two-sided cotton / polyester mixed fabric from production scraps of the “TAD” dyehouse. It is in the form of fabric squares measuring 1.5x1.5 cm. It contains a mixture of unknown disperse / reactive dyes with azo / anthraquinone chemical structures.The MT14 textile material is an intimate blend of viscose and polyester from production scraps from the "TAD" dyehouse. It is in the form of fabric squares measuring 1.5x1.5 cm. It contains a mixture of unknown disperse / reactive dyes with azo / anthraquinone chemical structures.

[0213] 30 mg of the textile material MT11 (respectively 30 mg of the textile material MT12, 30 mg of the textile material MT13, 34 mg of the textile material MT14) are introduced into a 2 ml container and then 0.90 g (1.03 g for MT14) of a deep eutectic solvent SI as defined in Example 1 is added to form a resulting composition comprising MT11 immersed in SI. The mass ratio of solid (MT11) / liquid (SI) (respectively (MT12) / (SI), (MT13) / (SI), (MT14) / (SI)) is 1 / 30.

[0214] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 19 hours 30 minutes.

[0215] The partially bleached textile material obtained was washed with ethanol twice and dried at 80°C for 1 hour. The materials from MT11, MT12, MT13 were bleached on the polyester side (white appearance). The cotton side remained intact and colored, which shows the selective bleaching of these complex fabrics, without fiber degradation. The material from MT14 was partially bleached, which shows the selective bleaching of these complex fabrics, without fiber degradation.

[0216] Figure 6 shows the textile material MT11 before bleaching (top) and then after bleaching (bottom) of the cotton side (left) and the polyester side (right) (Figure 6a) and the textile material MT14 before bleaching (top) and then after bleaching (bottom) (Figure 6b).

Claims

Claims 1. Use of a deep eutectic solvent for bleaching a colored textile material, said deep eutectic solvent comprising at least one hydrogen bond donor compound and at least one hydrogen bond acceptor compound different from the hydrogen bond donor compound, at least one of said hydrogen bond donor compound or hydrogen bond acceptor compound being an organic compound and at least one of said hydrogen bond donor compound or hydrogen bond acceptor compound being a non-ionic compound.

2. Use according to claim 1, characterized in that the molar ratio of hydrogen bond acceptor compound / hydrogen bond donor compound ranges from 1 / 30 to 16 / 1.

3. Use according to any one of the preceding claims, characterized in that the hydrogen bond acceptor compound present in the deep eutectic solvent represents at least 3 mol% relative to the total number of moles of compounds forming the deep eutectic solvent; and the hydrogen bond donor compound present in the deep eutectic solvent represents at least 3 mol% relative to the total number of moles of compounds forming the deep eutectic solvent.

4. Use according to any one of the preceding claims, characterized in that the hydrogen bond(s) acceptor compound is chosen from ammonium salts, phosphonium salts, metal salts, alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, sugars, surfactants, amines, and cyclodextrins.

5. Use according to any one of the preceding claims, characterized in that the hydrogen bond donor compound is chosen from ammonium salts, phosphonium salts, metal salts, alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, amides, sugars, and amines.

6. Use according to any one of the preceding claims, characterized in that the deep eutectic solvent comprises a compound ionic as a hydrogen bond acceptor compound and a non-ionic compound as a hydrogen bond donor compound.

7. Use according to any one of the preceding claims, characterized in that the deep eutectic solvent has a water content lower than the content of each of the hydrogen bond acceptor(s) and hydrogen bond donor(s) compounds of the deep eutectic solvent; or the deep eutectic solvent comprises at most 5% by mass of water relative to the total mass of the deep eutectic solvent.

8. Use according to any one of the preceding claims, characterized in that the textile material comprises polyester, viscose, acrylic, wool, silk, cotton, polyamide, or one of their mixtures.

9. Use according to any one of the preceding claims, characterized in that the colored textile material is dyed with one or more organic dyes.

10. Use according to any one of the preceding claims, characterized in that the colored textile material is dyed with one or more dyes which are disperse dyes, vat dyes, reactive dyes, direct dyes, acid dyes, or basic dyes.

11. A method of bleaching at least one colored textile material, characterized in that it comprises at least the following steps: i) bringing at least one colored textile material into contact with a deep eutectic solvent to form a resulting composition comprising said colored textile material and said deep eutectic solvent, and ii) heating said resulting composition to a heating temperature ranging from 50 to 150°C, said deep eutectic solvent being as defined in any one of claims 1 to 7.

12. Method according to claim 11, characterized in that step i) is carried out with a mass ratio of colored textile material / deep eutectic solvent ranging from 1 / 80 to 1 / 10.

13. Method according to claim 11 or 12, characterized in that it further comprises a step iii) of separating the discolored textile material.

14. Method according to any one of claims 11 to 13, characterized in that the colored textile material is dyed with one or more organic dyes.

15. Method according to any one of claims 11 to 14, characterized in that it further comprises a step vi) of recovering the dyes, preferably in solid form.

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