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

Abstract

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. Figure to be published: figure 1

Description

Title of the invention: 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 was 107 million tons, with an estimated PET fiber production of 55.1 million tons. Today, global PET fiber production is over 70 million tons, requires a large consumption of non-renewable oil, and PET has resistance to biodegradation. It is estimated that by 2050, textile production will consume 300 million tons of oil 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, significant releases 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. Furthermore, 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 (carcinogenic, mutagenic, and toxic to reproduction). On the other hand, the structures of synthetic dyes have been designed to be difficult to degrade to ensure good color fastness.This raises the problem of both recycling textile fibres and bleaching them and / or treating coloured effluents.

[0004] Several chemical and physical methods have been developed for the recycling of PET. For example, polyester is depolymerized by various chemical processes, particularly by glycolysis, then the monomers are purified. This type of process is, however, very expensive and difficult to industrialize. Furthermore, difficulties have been encountered in textile recycling when it comes to processing fabrics of mixed and colored fibers. During depolymerization, large quantities of dyes, often toxic, are eliminated in the effluents. Cotton is most often ground and then subjected to a bleaching process before weaving new fibers. The mechanical recycling of cotton must adapt 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 the finished products. As a result, most PET textiles are ultimately landfilled or incinerated at the end of their life; and less than 1% of fibers used in clothing are recycled for clothing production.

[0005] Furthermore, although 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, in particular using sodium hydrosulfite, sodium formaldehyde sulfoxylate or sodium hypochlorite. However, these oxidation-reduction methods in an aqueous medium destroy the dyes. In addition, they affect the structure of the fibers and / or their strength, and alter the colorability of the regenerated fibers. In addition, they are a significant source of effluents 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 uses the adsorption of the dyes, which requires the use of a significant quantity of solid material (activated carbons 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 beyond 100°C at normal pressure conditions. By Elsewhere, 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 solvents, very volatile and sometimes toxic, are used.

[0008] Therefore, there is a need to develop a simple and environmentally friendly bleaching method which allows, on the one hand, the recovery of textile fibres 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 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 retaining 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 volatility, liquid over 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 the 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 distinguished in particular 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 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] 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.

[0018] In particular, the hydrogen bond acceptor compound / hydrogen bond donor compound molar ratio 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.

[0019] The deep eutectic solvent preferably consists of hydrogen bond acceptor compound(s) and hydrogen bond donor compound(s).

[0020] According to a particularly preferred embodiment, the deep eutectic solvent consists of one or two hydrogen bond acceptor compound(s) and one or two hydrogen bond donor compound(s).

[0021] The deep eutectic solvent may comprise at most three hydrogen bond acceptor compound(s) and / or at most three hydrogen bond donor compound(s).

[0022] 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.

[0023] 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).

[0024] In the first case, the water content in the deep eutectic solvent is lower than that of each of the hydrogen bond acceptor(s) and hydrogen bond donor(s) compounds of the deep eutectic solvent.

[0025] 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.

[0026] The hydrogen bond acceptor compound

[0027] 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.

[0028] 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%, and particularly preferably at least approximately 5 mol%, relative to the total number of moles of compounds forming the deep eutectic solvent.

[0029] 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).

[0030] According to a preferred embodiment of the invention, the hydrogen bond acceptor compound (respectively each hydrogen bond acceptor compound 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.

[0031] The hydrogen bond acceptor compound may be chosen from ammonium salts, phosphonium salts, metal salts, alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, sugars, surfactants, amines, and cyclodextrins.

[0032] 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 [N 1011 l][Br], dodecyltrimethylammonium bromide [N 1211 l][Br], tetradecyltrimethylammonium bromide [N14111][Br], diethylammonium chloride [N22][C1], tetraethylammonium bromide [N2222][Br], tetraethylammonium chloride [N2222][C1], tetraethylammonium tosylate [N2222][TsO], tetrapropylammonium chloride [N3333][C1], butyltrimethylammonium [N4111][C1], butyltriethylammonium chloride [N4222][C1], tetrabutylammonium bromide [N4444][Br], tetrabutylammonium chloride [N4444][C1], tetraheptylammonium chloride [N7777][C1], methyltrioctylammonium bromide [N8881][Br],methyltrioctylammonium chloride [N8881][C1], tetraoctylammonium bromide [N8888][Br], tetraoctylammonium chloride [N8888][C1], cholinium bromide [Ch][Br], cholinium chloride [Ch][Cl], and phosphocholinium chloride [PCh][Cl].

[0033] 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][C1], [P888]O, allyltriphenylphosphonium bromide [PPh3All][Br], benzyltriphenylphosphonium chloride [PPh3Bz][Cl], methyltriphenylphosphonium bromide [PPh3Me][Br], tetrabutylphosphonium bromide [P4444][Br], and ethyltriphenylphosphonium iodide [PPh3Et][I].

[0034] Examples of metal salts as hydrogen bond acceptor compounds include transition metal chlorides such as ZnCl2, ZrOCl2, CrCl3, and FeCl3.

[0035] As examples of alcohols as hydrogen bond acceptor compounds, mention may be made of phenols and alcohols (eg -CHOH function) such as carvacrol, bomeol, menthol, and thymol.

[0036] In the invention, fatty alcohols are defined as alcohols which comprise at least one linear aliphatic hydrocarbon chain having at least 6 carbon atoms.

[0037] As examples of fatty alcohols as bond acceptor compounds: hydrogen, we can cite tetradecanol, octanol, decanol, and dodecanol.

[0038] Examples of carboxylic acids as hydrogen bond acceptor compounds include citric acid and malic acid.

[0039] 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.

[0040] Examples of fatty acids as hydrogen bond acceptor compounds include decanoic acid, dodecanoic acid, nonanoic acid, and octanoic acid.

[0041] Examples of amino acids as hydrogen bond acceptor compounds include proline, alanine, betaine, and carnitine.

[0042] Examples of sugars as hydrogen bond acceptor compounds include fructose, glucose, sucrose, and xylose.

[0043] Examples of amines as hydrogen bond acceptor compounds include diethanolamine, tetramethylguanidine, and ethanolamine.

[0044] Examples of surfactants as hydrogen bond acceptor compounds include octylphenoxypolyethoxyethanol (well known under the trade name "triton X-100"), sodium dodecyl sulfate, and sodium 1,4-bis-2-ethylhexylsulfosuccinate.

[0045] Examples of cyclodextrins as hydrogen bond acceptor compounds include α-[3- and γ-cyclodextrins.

[0046] The hydrogen bond donor compound(s)

[0047] 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.

[0048] The hydrogen bond donor compound(s) (respectively each hydrogen bond donor compound if there are several) present in the deep eutectic solvent preferably represents at least approximately 3 mol%, and particularly preferably at least approximately 5 mol%, relative to the total number of moles of compounds forming the deep eutectic solvent.

[0049] 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).

[0050] According to a preferred embodiment of the invention, the donor compound of hydrogen bond(s) (respectively each hydrogen bond donor compound if there are several) present in the deep eutectic solvent has any 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.

[0051] The hydrogen bond donor compound makes it possible to modulate the polarity, hydrophobicity, acidity and viscosity of the deep eutectic solvent, and thus to adapt to the type of fabric to be bleached.

[0052] The hydrogen bond donor compound may be chosen from ammonium salts, phosphonium salts, metal salts, alcohols, fatty alcohols, carboxylic acids, fatty acids, amino acids, amides, sugars, and amines.

[0053] Some of the aforementioned types of compounds can behave as both hydrogen bond acceptors and hydrogen bond donors depending on the chemical groups they contain.

[0054] As examples of ammonium salts as hydrogen bond donor compounds, mention may be made of ammonium halides, and preferably ammonium chlorides, such as cholinium chloride [Ch][Cl], and phospho-cholinium chloride [PCh][Cl].

[0055] Examples of phosphonium salts as hydrogen bond donor compounds include phosphonium carboxylates such as tetrabutylphosphonium acetate [P4444][OAc] and tetrabutylphosphonium levulinate [P4444][Lev],

[0056] Examples of metal salts as hydrogen bond donor compounds include transition metal, poor metal, and alkaline earth metal chlorides such as MgCl2, SnCl2, Zn(NO3), ZnBr2, ZnCl2, CrCl3, and FeCl3.

[0057] As examples of alcohols as hydrogen bond donor compounds, mention may be made of 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, phenethyl alcohol, sobrerol, sorbitol, tetraethylene glycol, triethylene glycol, xylenol, xylitol, 4-chlorophenol, m-cresol, o-cresol, sesamol, phenol, 4-phenylphenol, 4-cyanophenol, and hydroquinone.

[0058] Examples of fatty alcohols as hydrogen bond donor compounds include octanol, decanol, dodecanol, hexadecanol, hexanol, and tetradecanol.

[0059] 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.

[0060] 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.

[0061] Examples of amino acids as hydrogen bond donor compounds include proline, alanine, glycine, and serine.

[0062] Examples of sugars as hydrogen bond donor compounds include fructose, glucose, sucrose, xylose, and maltose.

[0063] Examples of amides as hydrogen bond donor compounds include urea, methylurea, acetamide, N,N-dimethylurea, 2,2,2-trifluoroacetamide, thiourea, and lidocaine.

[0064] Examples of amines as hydrogen bond donor compounds include ethanolamine, imidazole, and triethanolamine.

[0065] The deep eutectic solvent

[0066] The deep eutectic solvent preferably comprises an ionic compound as a hydrogen bond acceptor compound and a non-ionic compound as a hydrogen bond donor compound.

[0067] 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.

[0068] 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 salt / amide.

[0069] The deep eutectic solvent is preferably liquid at a temperature greater than or equal to approximately 60°C.

[0070] The textile material

[0071] The textile material is preferably in the form of fibers. In other words, the textile material is preferably a fibrous material.

[0072] The textile material may be one or more fibers, one or more yarns, one or more fabrics, or a mixture thereof.

[0073] Preferably, the textile material comprises (or is made of) polyester, viscose, acrylic, wool, silk, cotton, polyamide (e.g. Nylon), or a mixture thereof.

[0074] 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.

[0075] The textile material is dyed (colored) with one or more dyes.

[0076] The dyes may be disperse dyes, vat dyes, reactive dyes, acid dyes, or basic dyes.

[0077] Reactive dyes are widely used in the dyeing of cellulosic fabrics, such as cotton or viscose, and fabrics of animal origin such as wool or silk.

[0078] Vat dyes are also used for dyeing cellulosic textile materials.

[0079] Disperse dyes enable the dyeing of hydrophobic thermoplastic fibers, including nylon, polyester, acrylic, and other synthetic fibers.

[0080] Acid dyes are widely used in dyeing wool, silk, and polyamide fibers.

[0081] Basic dyes are used in dyeing wool, silk, and acrylic fibers.

[0082] 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.

[0083] According to this first variant, the deep eutectic solvent preferably has a pH ranging from approximately 9 to 13.

[0084] 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).

[0085] 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.

[0086] According to a second variant, the textile material comprises polyester or acrylic (or is made of polyester and / or acrylic) and it is colored with at least one disperse dye.

[0087] According to this second variant, the deep eutectic solvent preferably has a pH ranging from approximately 2 to 9.

[0088] 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.

[0089] 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.

[0090] According to this third variant, the deep eutectic solvent preferably has a pH ranging from approximately 2 to 6.

[0091] 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.

[0092] 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.

[0093] 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 process is highly modular in that it is possible to adapt the deep eutectic solvent to the nature of the colored textile materials and / or the nature of the dyes they contain. Recovery of the dyes in the solid state limits 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 process steps that can reach temperatures above 100°C.

[0094] Step i)

[0095] 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.

[0096] The colored textile material is preferably as defined in the first subject of the invention.

[0097] Step i) can be carried out by immersing the colored textile material in the deep eutectic solvent. This makes it possible to cover the entire surface and volume of the textile material and completely impregnate it with the deep eutectic solvent.

[0098] Step i) may be preceded by a step iO) in which the colored textile material is fractionated, in particular cut into pieces. This thus makes it possible to promote the bleaching reaction.

[0099] 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).

[0100] Step i) is preferably carried out at atmospheric pressure.

[0101] Step i) is preferably implemented with a material mass ratio colored textile / deep eutectic solvent ranging from about 1 / 80 to about 1 / 10, and particularly preferably from about 1 / 50 to about 1 / 10. These value ranges both promote bleaching and avoid excessive solvent consumption for environmental reasons, while still having enough solvent to wet the fabrics to be bleached.

[0102] At the end of step i), the resulting composition preferably consists of the colored textile material and the deep eutectic solvent.

[0103] 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.

[0104] Step ii)

[0105] Step ii) involves heating the resulting composition to a temperature heating ranging from approximately 50 to 150°C.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] Step ii) can last from 1h to 48h approximately, and preferably from 1h to 10h approximately.

[0111] Step ii) is preferably carried out with stirring.

[0112] Step ii) is preferably carried out at atmospheric pressure.

[0113] 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).

[0114] Step iii)

[0115] The method may further comprise a step iii) of separating the discolored textile material. The method of the invention thus makes it possible to recover the textile material and the dyes without degradation.

[0116] The textile material is then recovered in the solid state at the end of step iii).

[0117] Step iv)

[0118] 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.

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

[0120] 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.

[0121] The method may comprise a step vi) of recovering the dyes, preferably in solid form, in particular using an anti-solvent. This may then make it possible to recover the dyes in the solid state.

[0122] The anti-solvent 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.

[0123] The anti-solvent allows the dye(s) to precipitate.

[0124] 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.

[0125] The method according to the second object of the invention can in particular make it possible to separate different types of textile materials by modifying one or more parameters, for example chosen from temperature and deep eutectic solvent, and their combination.

[0126] 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) contacting at least one colored textile material MT comprising FA and FB 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 decolorize 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) contacting the textile material MT comprising bleached FA and colored FB 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 bleached FA and bleached 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.

[0127] The textile material MT comprising bleached FA and colored FB can be washed and dried, in particular after the separation step iii).

[0128] The textile material MT comprising bleached FA and bleached FB can be washed and dried, in particular after the separation step iii').

[0129] The invention thus relates to a method for selectively bleaching at least two different colored textile materials MTA and MTB, said method comprising at least the following steps: (i) bringing into contact at least two colored textile materials MTA and MTB with a first deep eutectic solvent to form a resulting composition, and ii) heating said resulting composition to a first heating temperature ranging from about 50 to 150°C, so as to selectively decolorize MTA, said first deep eutectic solvent being a deep eutectic solvent as defined in the first subject of the invention, iii) optionally separating the decolorized MTA textile material and the colored MTB textile material from the resulting composition, i') contacting the colored MTB textile material, optionally mixed with decolorized 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 about 50 to 150°C, so as to selectively decolorize MTB, said second deep eutectic solvent being a deep eutectic solvent as defined in the first subject of the invention,iii') separating the bleached 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.

[0130] The bleached MTA textile material can be washed and dried, particularly after separation step iii).

[0131] The bleached MTB textile material can be washed and dried, particularly after separation step iii').

[0132] The present invention is illustrated by the following exemplary embodiments, to which it is however not limited. Brief description of the drawings

[0133] The invention is illustrated by the following figures and examples.

[0134] [Fig.l] shows the discoloration of several textile materials according to a method according to the invention.

[0135] [Fig.2] shows optical microscopy images of the fibers before and after bleaching.

[0136] [Fig.3] shows the discoloration of a textile material according to a method according to the invention.

[0137] [Fig.4] shows an image of the recovery of a dye in the solid state.

[0138] [Fig.5] shows the stability of the dye during bleaching according to a method according to the invention.

[0139] Examples

[0140] The raw materials used in the examples are listed below: - MT1 textile material: orange TAD-dyed polyester, code DO30, - textile material MT2: green polyester from Recyc'Elit, code RcE 3, - textile material MT3: red polyester dyed by TAD, code DR167, - textile material MT4: pink polyester from Recyc'Elit, code RcE 4, - textile material MT5: blue polyamide scraps from TAD, code PA-B, - textile material MT6: green polyamide scraps from TAD, code PA-V, - textile material MT7: green cotton scraps from TAD, code Co-V, - textile material MT8: dark blue viscose and polyester scraps from TAD, code V / PES-B, - MT9 textile material: cotton and polyester scraps from TAD, dark grey in colour, 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.

[0141] Unless otherwise stated, all materials were used as received from the manufacturers, without purification.

[0142] Colorimetry measurements

[0143] Colorimetric measurements were carried out on the textile materials before and after bleaching with a KONICA MINOLTA CM-23d portable spectrophotometer, with Xenon source, under illuminant D65, a standard observation of 10° and specular reflection included.

[0144] The device was connected to the SpectraMagic NX Pro v3.4 software during the measurements.

[0145] 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 derived 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 = iqq x

[0146] Measurements of UV-Visible absorption of dyes

[0147] UV-Visible spectroscopy measurements were carried out for some 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 the deep eutectic solvents. The absence of degradation was verified by comparing the UV-Visible absorption spectra with those of the respective commercial dyes.

[0148] 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 to 750 nm, with a measurement step of 1 nm. Two quartz cuvettes with an optical path of 1 cm were used as reference and sample cuvettes.

[0149] For each sample, a baseline was first measured by adding the same reference solvent to both tanks 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 tank with a solution containing the colored sample, diluted with the reference solvent.

[0150] The wavelength in nm of the UV-Visible absorption maximum of the extracted and commercial dyes was read directly from the corresponding spectra.

[0151] Example 1: process for bleaching a textile material MT1

[0152] In this example 1, the textile material MT1 is in the form of squares of fabric of dimension 1.5x1.5 cm. It comprises a disperse dye well known as Disperse Orange 30 (2-[N -(2-cyanoethyl)-4-[(2,6-dichloro-4-nitrophenyl)azo]anilino]ethyl acetate). It has an azo-like 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 to 1,4-butanediol of 1:3. The solid (MT1) to liquid (SI) mass ratio is 1:30.

[0153] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 24 hours.

[0154] 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%.

[0155] The resulting colored composition comprising the deep eutectic solvent SI and the dye extracted from the textile material MT1 is filtered with a polytetrafluoroethylene syringe filter. fluoroethylene (PTFE) and glass fibers, 13 mm in diameter and 22 pm in pore size. 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 MT1 textile material is observed after 20 hours. The mixture is centrifuged at room conditions for 1 hour 30 minutes, at 9500 rotations per minute, to separate the liquid (deep eutectic solvent SI and water) and solid (dye extracted from the MT1 textile material) phases. The use of an anti-solvent such as water thus allows the recovery of the dye in the solid state.

[0156] UV-Visible spectroscopy of the resulting colored composition (dye extracted from the textile material MT1 dissolved in SI)

[0157] 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.

[0158] The absence of degradation of the dye extracted from the textile material MT1 is verified by measuring the maximum UV-Visible absorption 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.

[0159] 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 extracted dye is 435 nm. This confirms the absence of degradation of the color during the bleaching process of the invention.

[0160] Example 2: process for bleaching a textile material MT2

[0161] In this example 2, the textile material MT2 is in the form of squares of fabric of dimension 1.5x1.5 cm. It includes 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.

[0162] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 24 hours.

[0163] 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%.

[0164] Example 3: process for bleaching a textile material MT3

[0165] In this example 3, the textile material MT3 is in the form of squares of fabric of dimension 1.5x1.5 cm. It comprises a disperse dye well known as 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 S 2 is added to form a resulting composition comprising MT3 immersed in S 2. The deep eutectic solvent S2 comprises tetraethylammonium chloride as a hydrogen bond acceptor and 1,4-butanediol as a hydrogen bond donor, with a tetraethylammonium chloride / 1,4-butanediol molar ratio of 1 / 2. The solid (MT3) / liquid (S2) mass ratio is 1 / 30.

[0166] 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%.

[0167] 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.

[0168] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 21 hours.

[0169] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. The bleaching rate %D is 99.2%.

[0170] Example 4: process for bleaching a textile material MT4

[0171] In this example 4, the textile material MT4 is in the form of squares of fabric of dimension 1.5x1.5 cm. It includes 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.

[0172] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 19 hours. It has a white appearance.

[0173] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour.

[0174] 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.

[0178] Example 6: process for bleaching a textile material MT5

[0179] In this example 6, the textile material MT5 is in the form of squares of fabric of dimension 1.5x1.5 cm. It comprises a mixture of acid dyes. The chemical structures are anionic, azo and anthaquinone. 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.

[0180] 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.

[0181] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour.

[0182] Example 7: process for bleaching a textile material MT6

[0183] In this example 7, the textile material MT6 is in the form of squares of fabric of dimension 1.5x1.5 cm. It comprises a mixture of acid dyes. The chemical structures are anionic, azo and anthaquinone. 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.

[0184] The resulting composition is heated to 100°C with stirring (rotation at 100 revolutions per minute) for 6 hours. It has a white appearance.

[0185] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour.

[0186] Example 8: process for bleaching a textile material MT7

[0187] In this example 8, the textile material MT7 is in the form of squares of fabric 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 molar ratio of choline chloride to ethanolamine of 1:6. The mass ratio of solid (MT7) to liquid (S4) 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 and the discoloration rate %D is 95.4%.

[0189] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour.

[0190] Example 9: process for bleaching a textile material MT8

[0191] In this example 9, the textile material MT8 is in the form of squares of fabric 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.

[0192] 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%.

[0193] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour.

[0194] Example 10: process for bleaching a textile material MT9

[0195] In this example 10, the textile material MT9 is in the form of squares of fabric of dimension 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.

[0196] 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%.

[0197] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour.

[0198] Example 11 of characterization of the discolored textile materials of examples 1-10

[0199] [Fig. 1] shows: - the textile material MT1 before discoloration then after discoloration ([Fig.l] a), - the MT2 textile material before discoloration then after discoloration ([Fig.l] b), - the MT3 textile material before discoloration then after discoloration ([Fig.l] c), - the MT4 textile material before discoloration then after discoloration ([Fig.l] d), - the MT3 textile material before discoloration then after discoloration ([Fig.l] e), - the MT5 textile material before discoloration then after discoloration ([Fig.l] f), - the MT6 textile material before discoloration then after discoloration ([Fig.l] g), - the MT7 textile material before discoloration then after discoloration ([Fig.l] h), - the MT8 textile material before discoloration then after discoloration ([Fig.l] i), - the MT9 textile material before discoloration then after discoloration ([Fig.l] j).

[0200] [Fig.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.

[0201] [Fig.2] represents in particular: - the MT1 textile material before discoloration ([Fig.2] a) then after discoloration ([Fig.2] b), - the MT6 textile material before discoloration ([Fig.2] c) then after discoloration ([Fig.2] d), and - the MT7 textile material before discoloration ([Fig.2] e) then after discoloration ([Fig.2] f).

[0202] [Fig.2] shows that the textile materials are intact after discoloration.

[0203] Example 12: process for bleaching a textile material MT10

[0204] In this example 12, the textile material MT10 is in the form of fabric squares measuring 1.5x1.5 cm. It includes 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 MT10 textile material is introduced into a 4 ml container followed by 1.95 g of a eutectic solvent deep SI as defined in Example 1 are added to form a resulting composition comprising MT10 immersed in SI. The solid (MT10) / liquid (SI) mass ratio is 1 / 30.

[0205] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) 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%.

[0206] A new bleaching cycle is carried out with the blue textile material obtained (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.

[0207] The resulting composition is heated to 130°C with stirring (rotation at 100 revolutions per minute) for 20 hours.

[0208] The bleached textile material is washed with ethanol twice and dried at 80°C for 1 hour. The bleaching rate %D is 96.7%.

[0209] [Fig.3] shows the MT10 textile material before discoloration ([Fig.3] a) and then after discoloration ([Fig.3] b).

[0210] Recovery of the dye in the solid state

[0211] 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 pm. 131 mg of the resulting colored composition are 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 hours. The mixture is left for sedimentation.

[0212] [Fig.4] shows an image of the recovery of Disperse Blue 60 dye in the solid state (precipitation).

[0213] UV-Visible spectroscopy of the resulting colored composition (dye extracted from the MT10 textile material dissolved in SI)

[0214] 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.

[0215] 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 filtered resulting colored composition is diluted with 9.98 g (9 ml) of acidified DMSO. The dilution mass ratio is 1 / 50.

[0216] 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.

[0217] [Fig. 5] shows a UV-visible absorption spectrum of the commercial dye Disperse Blue 60 (solid curve) and of the resulting colored composition after bleaching according to 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).

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 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 an ionic compound as hydrogen bond acceptor compound and a non-ionic compound as hydrogen bond donor compound.

7. Use according to any one of the preceding claims, characterized in that the textile material comprises polyester, viscose, acrylic, wool, silk, cotton, polyamide, or a mixture thereof.

8. 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 6.

9. Method according to claim 8, 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.

10. Method according to claim 8 or 9, characterized in that it further comprises a step iii) of separating the discolored textile material.

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