Method and apparatus for removing dye from textile waste

Abstract

To recover a dye from textile waste containing at least 50 mass% of polyester fibers by a safe, easy and environmentally clean means.SOLUTION: A textile waste batch is extracted with a circulating solvent in an extraction chamber, the solution comprising the solvent and the extracted material is used as a dye extraction solvent from another textile waste batch, and the extraction process is repeated until the amount of extracted material in the solution reaches a concentration that impairs further dye extraction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method and plant for removing dyes from textile waste in order to recycle textile materials such as fabrics, yarns, filaments, and garments. More particularly, the present invention relates to a method for recovering polyester material from dyed fabric and garment waste. [Background technology]

[0002] Recycling pre-consumer, post-industrial, post-consumer, and post-consumer textiles (also known as "textile scrap" or "fabric scrap") has become a primary goal in the textile industry: new and efficient recycling methods are being actively investigated. One goal is to provide a method to ensure "fabric-to-fabric" recycling of materials present in widely used textiles and textiles, especially polyester. In other words, the industry is striving to produce polyester filaments from textile scrap rather than from discarded water bottles.

[0003] The challenges of using post-consumer textiles in these processes include residues of contaminants that cause chemical reactions that reduce the molecular weight of the polyester and other materials that weaken the fiber. The challenge in recycling fabrics containing polyester or cotton is essentially removing contaminants such as dyes and polyurethane materials (e.g., elastin filaments) from the polyester or cotton fibers and filaments of the fabric.

[0004] WO2022 / 118244 discloses the recycling of waste polyester materials (including textile scraps) by dissolving the polyester in a solution comprising hexafluoroisopropyl alcohol and chlorinated hydrocarbons and / or aromatic hydrocarbons. Prior to dissolution, a pretreatment using dichloromethane (DCM) is carried out to remove colorants and impurities from the PET bottles and textile scraps. This method does not provide efficient and complete removal of dyes.

[0005] US2022169786 discloses a method for producing decolorized polyester by removing colorant from polyester with a decolorizing agent containing a glycol ether type compound having a boiling point of 160°C or higher at atmospheric pressure while heating the decolorizing agent to a temperature at or below the melting point of the polyester.

[0006] EP3699355 discloses a method and system for decolorizing textile waste dyed with disperse dyes using a magnetically charged dye-absorbing material in a hydrothermal environment. The textile material is treated under agitation in a decolorizing reactor containing water and magnetically activated carbon as the dye-absorbing material, under autogenous pressure, such as that obtained when heated to approximately 100-170°C. An ultrasonic generator is used to promote the release of dye molecules from the textile into the water. The dye released from the polyester fibers is adsorbed by the magnetically charged carbon (which is collected at the end of the process by activating a magnetic field). Summary of the Invention [Problem to be solved by the invention]

[0007] Generally, known methods result in partial degradation of the polyester polymer material and / or cotton fibers and often only partial removal of the dye; in particular, Applicant has recognized that operation under mild conditions is necessary to reduce degradation of the polyester and / or cotton. Degradation of the polyester is detrimental to the reusability of the recovered polyester material. Similarly, degradation of the cotton fibers compromises the mechanical properties and possibly the appearance of yarns made from recycled cotton fibers.

[0008] In particular, it would be extremely useful to have a method that can remove all dyes (e.g., disperse and vat dyes), elastane filaments and decorations from dyed or printed / decorated textile materials in a short time without degrading or damaging the polyester and / or cotton fibers contained in the textile.

[0009] A further challenge is that polyester-based fabrics and garments often contain polyurethane materials (either as elastane-type filaments in fabric yarns or as printed layers on garments as decoration, for example in sports apparel). The presence of elastomeric materials presents a problem when polyester and / or cotton fibers are recycled. [Means for solving the problem]

[0010] It is an object of the present invention to solve the above problems and to provide a method for recycling polyester-containing textile waste, in particular a method for recovering dyes from waste comprising polyester fibers, which method provides a safe, easy, and environmentally clean means of recovering polyester material from textile waste. Another object of the present invention is to provide a method for removing dyes from polyester-containing textile waste with reduced or no degradation of the polyester material. A particular object of the present invention is to provide a method for removing dyes from polyester-containing textile waste that reliably achieves "fabric-to-fabric" recycling in an environmentally friendly (i.e., "clean") manner.

[0011] The bleached material is then recycled by methods known in the art. For example, bleached polyester material can be further recycled by depolymerizing the polyester material or recovering the polyester as staple fibers. Preferably, the bleached polyester material is converted into PET chips or beads for use in fiber spinning and / or molding processes, depending on the intended application. Cellulose fibers, such as cotton fibers, that may be present in the blended textile are processed together with the polyester fibers to remove dyes from the cotton fibers. The bleached cotton fibers are then removed, for example, by chemical or enzymatic digestion of the cellulosic fibers. Preferably, for example, if the textile material contains less than 30% by weight, preferably less than 20% by weight, of cotton, the textile material is pretreated to reduce the amount of cotton or to remove the cotton component in the textile material to be extracted.

[0012] Similarly, decolorized cotton or cellulosic material can be recycled in a manner known per se, for example by mechanically providing cellulose staple fibers (including regenerated cellulose fibers, e.g., cotton fibers or regenerated cotton fibers) (the staple fibers being processed into yarns).

[0013] In the case of pre-consumer materials, particularly those present in clothing or fabrics, the clothing or fabrics are recycled by bleaching them to a raw (undyed) state and subsequently dyeing or printing or both of the treated clothing.

[0014] The problem is solved by a method according to claim 1 and by an apparatus according to claim 15. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram of an embodiment of the method and apparatus of the present invention comprising one extraction chamber and one centrifuge. [Figure 2] FIG. 1 is a schematic diagram of an embodiment of the method and apparatus of the present invention comprising two extraction chambers and two centrifuges. [Figure 3] FIG. 1 is a schematic diagram of an embodiment of the method of the present invention comprising four extraction chambers and four centrifuges. [Figure 4] Photograph showing the appearance of a textile material (a small piece of polyester fabric) after the size reduction process and before the extraction process. [Figure 5] Photograph showing the appearance of the textile material (a small piece of polyester fabric) at the end of the process. DETAILED DESCRIPTION OF THE INVENTION

[0016] Thus, one object of the present invention is a method for removing dyes from textile materials, in particular textile waste, the textile materials comprising at least 50%, preferably at least 60%, more preferably at least 70% by weight of polyester fibres, said method comprising the following steps: a) providing a batch of textile material to an extraction chamber; b) extracting the textile material batch with a solvent to provide a solution comprising the solvent and extracted substances, the extracted substances including at least the dye, wherein the solvent is circulated into the extraction chamber, through the textile material, and out of the extraction chamber to extract the textile material, and wherein the textile material is stationary or substantially stationary during at least a portion of the extraction step, preferably during the entire extraction step; c) removing the solution comprising the solvent and extracted substances from the fabric. wherein the solution comprising the solvent and the extracted substances obtained in steps b) and / or c) is used as a solvent for extracting dye from another batch of textile material (denoted "another textile material batch"), and steps b) and c) are preferably repeated until the amount of extracted substances in the solution comprising the solvent and the extracted substances reaches a concentration that impairs further dye extraction.

[0017] Advantageously, it has been observed that the method of the present invention allows for the recycling of textile waste comprising polyester, e.g., polyester fibers, and particularly the removal of dyes from waste textile materials comprising polyester fibers, to be carried out in a safe, rapid, easy, and environmentally friendly manner. The method of the present invention also allows for the removal of dyes from textile waste comprising polyester fibers with reduced or no degradation of the polyester material in the textile waste. The method of the present invention allows for the effective removal of dyes from textiles containing both polyester and cotton. Advantageously, even when the textile waste also contains polyurethane materials (e.g., elastane) or polyurethane prints or coatings, the polyurethane materials are effectively removed. The method of the present invention allows for the effective isolation and recovery of polyester materials (e.g., polyester fibers and filaments) along with cellulosic materials from textile waste, e.g., textile waste containing multiple different dyes. Furthermore, it allows for the recovery of substantially all of the solvent used. In particular, the method of the present invention allows for solvent recovery rates of at least 99% and even 99.9% or more.

[0018] As used herein, the term "extracted material" refers to material, including dyes and possibly other components, that has been removed from waste textile material by treating the waste textile material in accordance with this specification, i.e., by extracting the waste textile material with a solvent.

[0019] According to a specific example, the extraction chamber (or extractor) is a device known in the art. For example, the extraction chamber (extractor) may be in accordance with the reactor disclosed in commonly owned pending application EP24157391 (the structure of the reactor is incorporated herein by reference). The reactor preferably comprises an openable reaction chamber configured to contain textile waste; the reactor is also connected to at least one tank containing at least one of fresh solvent and contaminated solvent, and a pump or other circulation means for circulating the solvent through the chamber and the textile contained therein. The reactor generally comprises a cargo or basket with perforated walls for containing the textile waste within the chamber, the basket being removable from the chamber. Preferably, the chamber comprises at least one perforated separation element housed within the basket to keep the textile stationary. Preferably, the extraction chamber is equipped with insulation to help maintain the solvent at the temperature required for optimal dye removal.

[0020] The textile material is held in a stationary (i.e., static) state within the extraction chamber. The terms "stationary" or "static" state define that the textile is contained within the extraction chamber and held there while the solvent is pumped through the textile material. The textile fills the chamber and therefore does not move with the solvent, i.e., does not move under the action of the solvent flow.

[0021] Preferred solvents are DMF (dimethylformamide) or DMAC (dimethylacetamide) or a mixture of DMF or DMAC with alkaline water, or mixtures thereof. Preferably, the solvent is DMF. In an embodiment for bleaching textiles containing or consisting of dyed cotton fibers, the solvent comprises DMF and alkaline water, preferably a reducing agent for the dye. As used herein, the term "alkaline water" refers to water having a pH of at least 10, e.g., in the range of 10 to 13.5. The pH is adjusted by adding a base, e.g., NaOH and KOH, to the water.

[0022] The solvent is heated to a temperature suitable for removing the dye from the fabric.

[0023] According to a specific embodiment, step c) comprises separating the solution comprising the solvent and the extracted substances from the textile material by centrifugation. Advantageously, after the extraction step is completed, the use of centrifugation (especially applied to textile materials impregnated with the solution comprising the solvent and the extracted substances) allows for effective separation of the textile material from the solution comprising the solvent and the extracted substances (which was trapped by the textile material), thus achieving particularly effective removal of the dye and residual solvent from the textile material. This further results in less energy consumption for drying the textile material recovered at the end of the method, since most of the solvent and / or the solution comprising the solvent and the extracted substances has already been removed. In addition, the use of centrifugal force also allows for a reduction in the number of extractions (step b)) required to remove the dye (and optionally other substances) from the textile material. Centrifugation is also a particularly safe technique for removing residual solvent from textiles. According to a specific embodiment, the centrifugation step is carried out in an extraction chamber; in other words, according to a specific embodiment, the extraction chamber is suitable for use as a centrifuge.

[0024] According to a specific embodiment, the extraction step b) lasts for a period of 2 to 20 minutes, preferably 5 to 15 minutes, more preferably 7.5 to 12.5 minutes, and most preferably 10 minutes. According to a specific embodiment, the centrifugation step of the method is preferably carried out for a period of 1 to 5 minutes; this results in a total process time of about 25 to 35 minutes to complete the removal of the dye from the textile pieces. The short time required by the present invention is a surprising result when compared to the time required by conventional methods.

[0025] According to a specific example, the temperature of the solvent (or the solution comprising the solvent and the extracted substance) in the extraction chamber is in the range of 80 to 140°C, preferably 82 to 135°C. The temperature is selected depending on the solvent used and the dye to be removed. For example, if the polyester is not dope-dyed, the maximum temperature is about 110°C. For example, when DMF is used as the solvent, the temperature of the solvent (or the solution comprising the solvent and the extracted substance) in the extraction chamber is about 90°C.

[0026] Advantageously, the solvent in contact with the textile material, i.e. the mixture of solvent and textile pieces, is maintained at a temperature according to the above disclosure. For this purpose, the parts of the device for containing the textile and the solvent are preferably thermally insulated; in particular, at least the ducts supplying the solvent / textile mixture to the extraction chamber and the centrifuge are thermally insulated. In a preferred embodiment of the plant, all ducts, pipes and tanks and reservoirs for containing the solvent are thermally insulated by means known per se in the art.

[0027] According to a specific embodiment, step b) is repeated at least twice, and preferably, between each repetition, recovery of the solution comprising the solvent and the extracted substances according to step c) is performed, preferably by centrifugation. In a specific embodiment, centrifugation is performed in an extraction chamber. For example, if the extraction chamber is a washer or solvent purifier, the extraction chamber can be centrifuged, optionally washed, and optionally dried. According to a specific embodiment, the extraction chamber is suitable for use as a centrifuge. According to a specific embodiment, centrifugation is performed at a force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1200, for a time in the range of 0.5 to 10 minutes, preferably 1 to 5 minutes. For example, centrifugation is performed at a force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for example 1200. In a specific embodiment, after each centrifugation, the solution of solvent and extracted substances is reused to process another batch of textile material.

[0028] According to an embodiment, a portion of the solution comprising the solvent and extracted substances obtained during step b) is removed from the extraction chamber before step c), in other words, in an embodiment, the solution comprising the solvent and extracted substances obtained during step b) is removed from the extraction chamber before step c).

[0029] According to a specific embodiment, step c) is carried out in a centrifuge. For example, the centrifuge is selected from a vertical peeler-type bottom discharge centrifuge, a horizontal peeler-type centrifuge, a horizontal pusher-type centrifuge, and a decanter-type centrifuge. According to a specific embodiment, the centrifuge comprises a filter and a scraper. According to a specific embodiment, the extraction chamber is suitable for use as a centrifuge.

[0030] In a specific embodiment, the centrifugation is followed by a washing step. Preferably, the washing step is carried out in a centrifuge. Preferably, washing is carried out in the centrifuge (e.g., in the extraction chamber, if the extraction chamber is suitable for use as a centrifuge). In this case, the centrifuged textile material is washed using fresh solvent supplied to the interior of the centrifuge via a solvent supply line; during the washing step, the centrifuge is rotated at a reduced speed, i.e., a speed effective for washing the textile pieces, preferably in the range of 300 to 700 rpm, more preferably 400 to 600 rpm. According to a specific embodiment, hot washing is carried out, i.e., the temperature of the solvent supplied to the centrifuge for the washing step is high enough to quickly raise the temperature of the mixture of textile pieces and solvent to a temperature equal to or higher than the temperature of the solvent used for extracting the textile material. The washing step is carried out for a time period ranging from 3 to 10 minutes, and more preferably, about 5 to 6 minutes is sufficient to remove residual dye. After washing, the textile is centrifuged again to remove any remaining solvent on the textile used in the washing step. The final content of solvent in the fabric pieces is generally 4-7% by weight; this has the advantage that a "ring cake" is formed at the end of the centrifugation process, i.e., a thin layer of small fabric pieces that adhere to the side walls of the centrifuge. Such a cake can be easily removed from the wall by a scraper.

[0031] After centrifugation and optional washing (usually with a solvent), the textile may be washed with water. In a specific embodiment, the washing with water is carried out in a centrifuge (e.g., in the extraction chamber, if the extraction chamber is suitable for use as a centrifuge). After centrifugation, optional washing (usually with a solvent), and optional washing with water, the textile is dried. For example, the centrifuged textile is transferred from the centrifuge to a drying device and dried. Advantageously, for example, during the drying process, the solvent and water are also recovered, recovered, and collected. According to a specific embodiment, after centrifugation and before drying, a sample of the textile, typically a treated textile piece, is checked in a quality control unit, where the amount of dye in the textile is measured according to techniques known in the art, for example, color measurement using a spectrophotometer, i.e., Datacolor. If the dye is still present in the textile in an unacceptable amount, the textile material is returned to the extraction chamber and extracted again according to step b) of the method of the present invention. If the dye has been sufficiently removed from the textile, the textile is removed from the quality control unit and dried. In a specific example, the fabric is subjected to a water wash to remove the original solvent, ie, DMF or DMAC, before being sent to a drying step.

[0032] According to a specific embodiment, the textile material obtained in step b) is preferably transferred from the extraction chamber to a storage tank before being transferred to the centrifuge. Advantageously, the textile material obtained in step b) is transferred from the extraction chamber to a storage tank, for example, when the centrifuge does not hold the entire amount of textile material processed in the extraction chamber. The textile material obtained in step b) is transferred from the extraction chamber to a storage tank, so that the textile material obtained in step b) is centrifuged while another batch of textile material is being extracted in the extraction chamber.

[0033] According to a specific example, if the amount of extracted substances in the solution comprising the solvent and extracted substances is at a concentration that would impair further dye extraction, the solution comprising the solvent and extracted substances is fed to a distillation apparatus, thereby separating the solvent from the extracted substances. In this case, the solvent is advantageously recovered and reused. Also, the extracted substances, such as dyes, elastane and / or other polyurethane materials, are recovered and further processed. For example, if all the textiles to be processed are dyed with the same dye (disperse or vat dye), the dye is also recovered and reused without further treatment or processing.

[0034] According to a specific example, the distillation, in particular the distillation of DMF, is carried out at a temperature ranging from 70 to 100°C, preferably from 75 to 95°C, more preferably from 80 to 90°C, and at a pressure ranging from 15 to 90 mbar, preferably from 20 to 85 mbar, more preferably from 40 to 80 mbar.

[0035] According to an embodiment, the textile material is provided to the extraction chamber in a form selected from powder, fibers, filaments, yarns, fabrics, fabric clippings (e.g., pieces), garments, garment clippings (e.g., pieces), and mixtures thereof. The powdered textile material can be obtained by grinding other forms of textile waste, such as fabrics or garments. According to an embodiment, the method of the present invention further comprises the step of grinding the textile waste to obtain a powder, preferably a polyester powder.

[0036] According to an embodiment, the method of the present invention further comprises the step of mechanically treating the textiles, preferably cloth and garments, to reduce their dimensions to obtain pieces of textiles, preferably cloth and garment pieces (i.e., cloth and garment clippings). In an embodiment, the material is fed to the extraction chamber after mechanical treatment in the form of cloth or garment pieces (i.e., clippings) (at least 90% of the pieces have dimensions between 1 and 50 mm).

[0037] According to a specific embodiment, the material is a polyester-based fabric, optionally containing elastane filaments, and is fed to the extraction chamber in the form of small pieces of fabric or clothing (i.e., clippings), where at least 90% of the fabric or clothing pieces have a dimension of 2-2.5 mm. Fabric and / or clothing pieces having said dimensions are obtained by techniques and means known per se in the art, for example, by cutting or shredding devices. According to another specific embodiment, the textile waste contains cotton fibers, preferably at least 50% cotton fibers; the fabric is fed to the extraction chamber in the form of pieces of fabric or clothing (i.e., clippings), where 90% of the fabric pieces have a dimension of at least 20 mm, preferably in the range of 20-50 mm.

[0038] The advantage of using textile waste, i.e., woven or knitted fabric in the form of reduced size pieces as described above, is that extraction times are dramatically reduced and the mixture of fabric pieces and hot solvent is easily transferred from one part of the equipment, i.e., plant, to another.

[0039] According to a specific example, when the textile material is 100% cotton and the textile is, for example, fabric and garment, a process of mechanically opening such textile (e.g., yarn, fabric, and garment) can be carried out to obtain fiber tufts. Methods for mechanically opening textiles are well known in the art. Machines known as tearing machines are commonly used to perform this task during the so-called tearing or unraveling process. Suitable machines are commercially available from Laroche (part of the Andritz Group (FR)) and other manufacturers, such as Dell'orco & Villani (IT) and Türzler (DE). A preferred tearing machine comprises a series of several rotating cylinders or drums covered with opening means, such as saw wires or steel pins that tear the textile, gradually opening the textile structure into fiber bundles or fiber tufts. The terms "tuft," "fiber tuft," and "tuft of fiber" thus refer to the known state of a woven fabric that is converted into a fibrous aggregate such as that obtained in a tearing machine, in which the fabric is processed through a series of rotating drums equipped with tearing means such as steel pins. Thus, the fibrous tuft obtained by the known machine is no longer in the form of a yarn, but is an aggregate or mass of fibers that is in a physical state similar to that of raw cotton and raw cotton after ginning.

[0040] According to a specific example, the textile material is mixed with the solvent in a bath ratio of textile pieces (kg):solvent (L) ranging from 1:8 to 1:20, preferably 1:10 to 1:20. The mixture (preferably having a slurry-like consistency) is then suitable for feeding along the apparatus, for example, from the extraction chamber to a centrifuge, for example, by pumping or a feeder screw or an Archimedes screw.

[0041] According to an embodiment, the textile material comprises a plurality of dyes. According to an embodiment, the polyester fibers in the textile material may comprise at least one dye selected from disperse dyes.

[0042] According to an embodiment, the textile waste may further comprise cellulose fibers, preferably cotton fibers. In an embodiment, the cellulose fibers, preferably cotton fibers, in the textile material may comprise at least one dye selected from vat dyes, reactive dyes, direct dyes, sulfur dyes, and mixtures thereof. In an embodiment, the cellulose fibers, preferably cotton fibers, in the textile material may comprise at least one vat dye, preferably indigo.

[0043] For example, fabrics recycled by the method of the present invention are polyester sports apparel (e.g., T-shirts) and garments that have decorations printed onto a thin layer or film of polyurethane material that is applied to the garment. The polyurethane layer is dissolved by a solvent, along with the ink that forms the decorative elements (e.g., logos or numbers, etc.).

[0044] As used herein, reference is made to "polyurethane materials" or PU materials; this term encompasses elastomeric materials used in yarns (e.g., elastane and spandex) and any other polyurethane materials that may be present on or in a fabric, for example, as part of a decoration (e.g., a printed decoration) or as a coating.

[0045] According to an embodiment, at least a portion of the polyester fibers are dyed, preferably with at least one disperse dye. According to an embodiment, all of the polyester fibers in the textile material are dyed, preferably with at least one disperse dye, optionally with a plurality of disperse dyes.

[0046] According to a specific embodiment, step b) is carried out one or more times, preferably each time in a different extraction chamber, and / or step c) is carried out one or more times, optionally each time in a different centrifuge. The extraction chambers are arranged in series. In one embodiment, each extraction chamber comprises a centrifuge.

[0047] According to a specific embodiment, the extraction chamber is a first extraction chamber, and after the first extraction step b), the textile material is fed from the first extraction chamber to a first centrifuge for a first removal step c). Thereafter, the textile material is fed from the first centrifuge to a second extraction chamber for a second extraction step b) and then from the second extraction chamber to a second centrifuge for a second removal step c). In a specific embodiment, the first and second extraction steps b) and the first and second removal steps c) are carried out in two different extraction chambers and two different centrifuges, respectively.

[0048] According to a specific example, several batches of textile waste are extracted with the same solvent batch. For example, after extraction in the second extraction chamber and complete removal of the dye, the solvent used in the second extraction chamber and / or the second centrifuge is preferably supplied from the second extraction chamber to the first extraction chamber for extracting the next batch of textile material. In this case, advantageously, the solvent (i.e., the solution comprising the solvent and the extracted substances) removed from the second extraction chamber and / or the second centrifuge is used to further increase the concentration of the extracted substances in the solution for extracting the next batch of textile material, thus reducing the amount of solvent required for the process. For example, the textile waste is extracted with the solvent in the first extraction chamber, centrifuged, then extracted again in the second extraction chamber, and subsequently centrifuged again, preferably in a second centrifuge. Fresh solvent may be used for the second extraction step. After the second extraction step, a solution comprising the solvent and extracted substances is obtained; the solution (including the residual solution recovered from the second centrifuge after centrifugation of the textile material after the second extraction and fed back to the second extraction chamber) is reused in the second extraction chamber for multiple extractions, for example, up to 20, preferably up to 30, and more preferably up to 40 extractions. At this point, the solution comprising the solvent and extracted substances is supplied to the first extraction chamber and reused for extracting textile waste until the extracted substances in the solution reach a concentration that impairs further dye extraction. When the extracted substances in the solution reach a concentration that impairs further dye extraction, the solution comprising the solvent and extracted substances is supplied to a distillation device, thereby distilling and recovering the solvent. In other words, when further dye extraction in the first extraction chamber is impaired, the solution comprising the solvent and extracted substances is supplied to a distillation device, and the solution comprising the solvent and extracted substances obtained in the second extraction chamber is supplied to the first extraction chamber.In this case, advantageously, the concentration of the extracted substances in the solution comprising the solvent and the extracted substances obtained in the second extraction chamber is not limiting, as long as the solution comprising the solvent and the extracted substances obtained in the second extraction chamber is suitable for carrying out extraction step b) on further textile batches in the first extraction chamber.

[0049] According to a specific example, steps b) and c) are repeated two or more times in two or more extraction chambers and centrifuges, with the solvent removed from any extraction chamber different from the first chamber being fed to the preceding extraction chamber. In this case, advantageously, the solvent (i.e., the solution comprising the solvent and the extracted substances) removed from any second or further extraction chamber is used to extract the next batch of textile material in the preceding extraction chamber, so that the concentration of the extracted substances in the solution increases whenever the solution moves from one extraction chamber to the preceding one, so that a new batch of textile material is extracted for the first time in the first extraction chamber with the solution comprising the solvent and the extracted substances, and then treated in the subsequent extraction chambers using solutions with progressively decreasing concentrations of the extracted substances.

[0050] According to a specific embodiment, the solvent (i.e., the solution comprising the solvent and extracted substances) exiting the extraction chamber is filtered to maximize the amount of fabric debris remaining in the extraction chamber and to keep the solution comprising the solvent and extracted substances solids-free.

[0051] According to an embodiment, the solvent used in step b) already contains extracted substances (the extracted substances include at least dyes) before the start of step b). In other words, according to an embodiment, the solvent used in step b) is in the form of a solution comprising the solvent and extracted substances (the extracted substances include at least dyes). In an embodiment, the solvent containing already extracted substances is supplied to the extraction chamber from a solvent storage tank. In an embodiment, such a solvent storage tank is configured to receive the solution comprising the solvent and extracted substances leaving the extraction chamber and / or the centrifuge. In an embodiment, the extracted substances in the solution may originate from other processes and / or plants. In an embodiment, the extracted substances in the solution may originate from a textile material batch already treated according to the method of the present invention.

[0052] According to a specific example, the solvent is DMF (dimethylformamide) or DMAC (dimethylacetamide) or a mixture of DMF or DMAC with alkaline water, or a mixture thereof. Preferably, the solvent is DMF. In a specific example, the solvent comprises DMF and alkaline water. As used herein, the term "alkaline water" refers to water having a pH of at least 10, for example, in the range of 10 to 13.5. The pH is adjusted by adding a base, for example, NaOH or KOH, to the water.

[0053] According to a specific example, the liquor ratio of fabric to solvent (kg / L) is in the range of 1 / 3 to 1 / 20, preferably 1 / 3.5 to 1 / 12, more preferably 1 / 4 to 1 / 10. In a specific example, the liquor ratio of fabric to solvent (kg / L) is in the range of 1 / 3 to 1 / 20, preferably 1 / 10 to 1 / 20. In a specific example, additional solvent and / or additional solution comprising solvent and extracted material is added to maintain the liquor ratio within the above-mentioned range.

[0054] According to a specific example, step c) is carried out in a centrifuge at a G-force in the range of 250-5000, preferably 800-2000, more preferably 900-1300, for a time in the range of 0.5-10 minutes, preferably 1-5 minutes. The force exerted on the sample in the centrifuge is a function of the rotation speed (RPM) of the centrifuge and the radius of the rotor. Knowing the radius of the rotor (cm), the formula for calculating the G-force (gravitational equivalent) is: G-force = 0.00001118 x rotor radius x (RPM) 2 According to an embodiment, the extraction chamber is suitable for use as a centrifuge.

[0055] In an embodiment, the textile waste may be pre-treated before being extracted according to step b), for example, the size of the textile waste is reduced, for example, by cutting the cloth or garment (e.g., 100% PET cloth or garment) into clippings, by cutting the clippings (e.g., 100% PET clippings) to further reduce their size, or by grinding the cloth or garment or clippings to obtain a powder (e.g., 100% PET powder).

[0056] According to a specific example, the material is pretreated to obtain pieces of fabric having dimensions of 1 to 50 mm, preferably 2 to 10 mm, and more preferably 2 to 2.5 mm. According to a specific example, when the textile material contains cotton (at least 50% cotton), the dimensions of the pieces are in the range of 20 to 50 mm. In a specific example, when the textile is 100% cotton and the textile is, for example, fabric and clothing, a step of mechanically opening such textile (e.g., yarn, fabric, and clothing) to obtain fiber tufts can be carried out. Pieces of fabric and / or clothing having the above dimensions can be obtained according to descriptions and machines known per se in the art, such as cutting devices or shredders.

[0057] In a specific example, waste textile material is reduced to fibers. For example, cloth, clothing, or clippings (e.g., 100% PET cloth, clothing, or clippings) are converted to fibers (e.g., 100% PET fibers). In a specific example, if the textile material contains 50% or less, preferably 30% by weight, cotton, the textile material is pretreated to reduce the amount of cotton in the extracted textile material. For example, the amount of cotton in the textile material is reduced by pretreating the textile scraps with cellulase enzymes or chemical reactants suitable for depolymerizing cotton (or other cellulosic materials) (e.g., treatment with inorganic or organic acids), according to techniques known in the art. In a specific example, if the textile material contains elastane fibers, the textile material can be pretreated to reduce the amount of elastane in the extracted textile material. For example, the amount of elastane in the textile is reduced by pretreating the textile scraps with DMF, according to techniques known in the art. Advantageously, the method of the present invention is particularly effective when it comprises a step of pre-treating the textile waste.

[0058] According to an embodiment, the textile material is made of polyester fibers. In other words, according to an embodiment, the textile material is selected from polyester fibers, polyester filaments, polyester yarns, polyester fabric, clippings of polyester fabric (i.e., 100% polyester fabric), polyester garment, clippings of polyester garment, and mixtures thereof. For example, the textile material is selected from polyester fibers (i.e., 100% polyester fabric), clippings made of polyester fibers (100% polyester fabric or clippings from textile), polyester fibers, and mixtures thereof. According to an embodiment, at least a portion of the polyester fibers in the textile material made of polyester fibers are dyed. According to an embodiment, all of the polyester fibers in the textile material made of polyester fibers are dyed. According to an embodiment, the textile material made of polyester fibers contains a plurality of dyes, for example, a plurality of disperse dyes.

[0059] According to a specific embodiment, the textile material is chosen from fabrics made of polyester fibers, clippings made of polyester fibers (i.e. pieces of fabric and / or clothing, optionally having the above dimensions) and mixtures thereof, at least some of the polyester fibers being dyed with at least one disperse dye. In this case, the solvent is preferably DMF, and the temperature of the solvent (or the solution comprising the solvent and the extracted substance) used in step b) in the extraction chamber is in the range of 85-105°C, preferably 95-100°C.

[0060] According to a specific example, the textile material is polyester fibers (i.e. separated fibers) and the polyester fibers are dyed with at least one disperse dye. In this case, the solvent is preferably DMF and the temperature of the solvent (or the solution comprising the solvent and the extracted substance) used in step b) in the extraction chamber is in the range of 80-110°C, preferably 85-105°C, for example 100°C.

[0061] According to a specific embodiment, the textile waste further comprises at least a polyurethane material, preferably elastane. According to a specific embodiment, the textile material comprises polyester fibers and further comprises at least one polyurethane material, preferably elastane. In this case, the polyurethane material, e.g., elastane, contained in the textile material is advantageously extracted together with the dye. For example, the textile material may comprise at least 90% by weight of polyester fibers and further comprise one or more polyurethane materials, preferably elastane, more preferably at most 10% by weight of elastane. In a specific embodiment, the textile material comprises 90% by weight of polyester fibers and 10% by weight of elastane.

[0062] According to a specific example, the textile material comprises at least 90% by weight of polyester fibres and at most 10% by weight of elastane fibres, at least some of the polyester fibres being dyed with at least one disperse dye. In this case, the solvent is preferably DMF, and the temperature of the solvent (or of the solution comprising the solvent and the extracted substance) used in step b) in the extraction chamber is in the range of 85-105°C, preferably about 95°C.

[0063] According to a specific example, the textile material comprises polyester fibers and further comprises at least one cellulose material, preferably cotton, for example, the textile material may comprise at least 50%, preferably 60%, more preferably 70% by weight of polyester fibers and further comprise cellulose fibers, for example at most 50%, preferably 40%, more preferably 30% by weight of cotton fibers.

[0064] According to embodiments, at least a portion of the cellulose fibers in the textile material are dyed. According to embodiments, all of the cellulose fibers in the textile material are dyed. According to embodiments, the textile material comprises cellulose fibers with a plurality of dyes, for example, a plurality of vat dyes.

[0065] According to a specific embodiment, the textile material comprises dyed cellulose fibers, preferably dyed cotton fibers. The dyed cellulose fibers comprise at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, sulfur dyes, and mixtures thereof. According to a specific embodiment, the textile material comprises dyed cellulose fibers, preferably dyed cotton fibers, and the solvent is preferably a mixture of DMF, water, and a base (optionally comprising a reducing agent). In other words, in a specific embodiment, the solvent is preferably a mixture of DMF and alkaline water (optionally further comprising a reducing agent). Suitable reducing agents are selected from the group consisting of alkali metal hydrosulfites, sulfites, thiosulfates, and oxalates; thiourea dioxide; alkali metal sulfoxylate formaldehyde, hydroxyacetone, and derivatives of sulfinic acid. For example, the reducing agent is NaSO. Suitable bases are NaOH, KOH, and mixtures thereof.

[0066] According to a specific example, the textile material comprises at least 50%, preferably 70%, by weight of polyester fibers and at most 50%, preferably 30%, by weight of cotton fibers, at least some of the polyester fibers being dyed with at least one disperse dye and at least some of the cotton fibers being dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulfur dyes. In this case, the solvent is preferably a mixture of DMF and water (comprising a base and optionally a reducing agent), and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in step b) and in the washing step in the centrifuge after the first centrifugation is in the range of 85-110°C, preferably about 95°C.

[0067] According to a specific example, the textile material comprises polyester fibers and further comprises at least a polyurethane material, preferably elastane, and at least one cellulose material, preferably cotton, more preferably cotton fibers. For example, the textile material may comprise at least 50%, preferably 60%, more preferably 70% by weight of polyester fibers and further comprise elastane and cellulose fibers, for example at most 50%, preferably 40%, more preferably 30% by weight of elastane fibers and cotton fibers.

[0068] According to a specific example, the textile material comprises at least 50%, preferably 70%, by weight of polyester fibers and at most 50%, preferably 30%, by weight of cotton fibers and elastane fibers, and at least some of the polyester fibers are dyed with at least one disperse dye and at least some of the cotton fibers are dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes. In this case, the solvent is preferably a mixture of DMF and water (comprising a base and optionally a reducing agent), and the temperature of the solvent (or the solution comprising the solvent and the extracted substances) used in step b) in the extraction chamber and in the washing step in the centrifuge after the first centrifugation is in the range of 95-105°C, preferably about 100°C.

[0069] According to an embodiment, the textile material may comprise cellulosic fibers dyed with at least one vat dye, and optionally with a plurality of vat dyes.

[0070] According to specific examples, the textile material may comprise a mixture of disperse and vat dyes, for example polyester fibers dyed with at least one disperse dye and cellulose fibers dyed with at least one vat dye.

[0071] According to a specific embodiment, the textile material comprises a vat dye different from indigo, and the solvent (or solution comprising the solvent and the extracted substances) further comprises water and a base, and optionally a reducing agent. Advantageously, the presence of the reducing agent allows the reduction of the vat dye to the corresponding leuco form, which allows the vat dye to be easily removed from the textile.

[0072] In a specific example, the vat dye is indigo. Advantageously, when the vat dye is indigo, it is not necessarily required that water, a base, and a reducing agent be present together with the solvent. In other words, the indigo is removed by a solvent (DMF, DMAC, or a mixture thereof) or by a solution comprising the solvent and the extracted substance, thereby not necessarily requiring the presence of water and a reducing agent. However, in a specific example, the vat dye is indigo and the solvent (or the solution comprising the solvent and the extracted substance) further comprises water, a reducing agent, and a base.

[0073] According to a specific embodiment, the textile material comprises at least one cellulosic material, preferably cotton, more preferably cotton fibers, and indigo.

[0074] In an embodiment, the solution obtained in steps b) and / or c) is used as a solvent for extracting dyes from other batches of textile material up to 20 times, preferably up to 30 times, more preferably up to 40 times.

[0075] In a specific example, when multiple extraction steps are performed (each extraction is performed in a different extraction chamber), the solvent (or a solution comprising the solvent and the extracted material) is used for up to 20, preferably up to 40, more preferably up to 60 extraction cycles, i.e., for 20 textile waste batches, preferably 40 batches, more preferably 60 batches. For example, assuming the use of three extraction chambers, the solvent will be used 20 times for the first extraction chamber (e.g., depending on the dye concentration of the textile waste), and the solvent used in the second and third extraction chambers will also be used 20 times in the second and third extraction chambers. After the dye in the solvent (i.e., the solution comprising the solvent and the extracted material) in the first extraction chamber reaches a concentration that impairs further dye extraction, the solvent in the second extraction chamber (which has already been used 20 times) is sent to the first extraction chamber and used again, for example, 20 times. Similarly, the solvent in the third chamber (which has already been used 20 times) is sent to the second extraction chamber and used again, for example, 20 times. For example, after the solvent has been used for 60 extractions, the extraction of the dye is impaired.

[0076] According to a specific example, the solution obtained in steps b) and / or c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are repeated until the amount of extracted dye in the solution comprising the solvent and the extracted substance reaches a concentration that impairs further dye extraction.

[0077] According to a specific example, the solution obtained in steps b) and / or c) is used as a solvent for extracting dyes and optionally polyurethane (preferably elastane) from another batch of textile material, and steps b) and c) are repeated until the solution comprising the solvent and the extracted substances reaches a viscosity that impairs further dye extraction.

[0078] As used herein, "dye extraction is impaired" means that the solvent used in the extraction process (i.e., in the first extraction chamber) is no longer able to reduce the amount of dye in the textile waste. This is verified by checking the concentration of the dye in the solvent (i.e., the concentration of the dye in the solution comprising the solvent, dye, and extracted materials). In other words, at this point, the solvent is saturated and has reached the limit of its extraction capacity based on the content of dye and non-PET materials. The saturation level of the solvent is measured by periodically analyzing samples taken from the non-saturated solution tank and / or along the line of the apparatus of the present invention.

[0079] According to a particular embodiment, during step b), the solvent or a solution comprising the solvent and the extracted substance enters the extraction chamber, circulates through the textile material and leaves the extraction chamber.

[0080] According to a specific example, during step b), the solvent or the solution comprising the solvent and the extracted substance circulates through the extraction chamber and the textile waste contained therein by entering the extraction chamber at an inlet, passing through the textile material to extract the textile material (while the textile material is in a stationary (i.e., static) or substantially stationary (substantially static) state), and exiting the extraction chamber at an outlet. The textile material, e.g., fabric or garment or fiber, is contained in the extraction chamber in a stationary, i.e., static state. Apart from possible movement imparted by the flow of solvent circulated through the static extraction chamber and through the textile, for example by a pump, the textile material is also in a stationary, i.e., static state.

[0081] Another object of the present invention is an apparatus for removing dyes from textile materials in a method according to the invention, comprising at least one extraction chamber adapted to treat the textile material with a solvent, at least one centrifuge for separating a solution comprising the solvent and extracted substances from the textile material, at least one fresh solvent storage tank, and at least one distillation apparatus, wherein the fresh solvent storage tank is adapted to supply clean solvent to the extraction chamber and the centrifuge and to receive solvent from the distillation apparatus, and wherein the distillation apparatus is adapted to receive the solution comprising the solvent and extracted substances from the extraction chamber and / or the centrifuge.

[0082] According to an embodiment, the fresh solvent storage tank is configured to supply fresh solvent to the centrifuge.

[0083] According to an embodiment, the extraction chamber is configured to be stationary, i.e., static, during operation, wherein the solvent (or a solution comprising the solvent and the extracted substance) is circulated through the static extraction chamber and the fabric by a circulation means, e.g., a pump. According to an embodiment, the extraction chamber is configured to also operate as a centrifuge. In this case, the extraction chamber and the centrifuge are the same device.

[0084] According to a specific embodiment, the apparatus further comprises at least one storage tank configured to receive the mixture of textile material and solvent from the extraction chamber, e.g. after step b) of the method, and to feed the textile material to the centrifuge, e.g. for carrying out step c).

[0085] According to specific examples, the apparatus may further comprise at least one solvent storage tank configured to supply the solvent or a solution comprising the solvent and the extracted substance to the extraction chamber and configured to receive the solution comprising the solvent and the extracted substance from the extraction chamber and / or from the storage tank and / or from the centrifuge.

[0086] According to an embodiment, the apparatus further comprises at least one distillation apparatus configured to receive a solution comprising the solvent and extracted substances from the extraction chamber and separate the extracted substances from the solvent. Preferably, the solution comprising the solvent and extracted substances from the extraction chamber is fed to the distillation apparatus when the amount of the solvent and extracted substances in the extracted solution reaches a concentration at which further dye extraction is impaired. In an embodiment, a suitable pressure value in the distillation apparatus is 15 to 90 mbar, preferably 20 to 85 mbar, and most preferably 40 to 80 mbar.

[0087] According to a specific example, the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, the extraction chambers and centrifuges being arranged in series, and the apparatus further comprises means for feeding the textile material along the series of extraction chambers and centrifuges to provide a flow of textile material, wherein at least one centrifuge is coupled to an extraction chamber in an upward direction with respect to the textile flow and another centrifuge is coupled to an extraction chamber in a downward direction with respect to the textile flow.

[0088] According to an embodiment, the centrifuge is selected from a vertical peeler-type bottom discharge centrifuge, a horizontal peeler-type centrifuge, a horizontal pusher-type centrifuge, and a decanter-type centrifuge. Preferably, the centrifuge comprises a filter for retaining fibers and particles exiting the centrifuge, and a scraper. The scraper is for removing wet cloth particles (which precipitate as a thin layer of chippings or as a cake after centrifugation) from the inner walls of the centrifuge. According to an embodiment, the extraction chamber is configured to also function as a centrifuge; in other words, in an embodiment, the extraction chamber is suitable for use as a centrifuge.

[0089] According to a specific embodiment, after centrifugation and optional solvent and water washing, and before drying, the textile is transferred to a quality control unit (where the amount of dye still present in the textile is measured). Thus, in a specific embodiment, the apparatus comprises a quality control unit, which measures the amount of dye present in the treated textile pieces after centrifugation and washing, but before drying. The amount of dye still present in the textile is measured according to techniques known per se in the art, for example, color measurement using a spectrophotometer, i.e., Datacolor. If the dye is still present in the textile in an unacceptable amount, the textile material is transferred to an extraction chamber and extracted again according to step b) of the method of the present invention. If the dye has been sufficiently removed from the textile, the textile is transferred to a drying unit. In a specific embodiment, the solution comprising the solvent and extracted substances leaving the centrifuge after centrifugation is filtered. Thus, according to a specific embodiment, the apparatus further comprises one or more filters configured to filter the solution comprising the solvent and extracted substances leaving the centrifuge after centrifugation. In a preferred embodiment, a washing device is provided upstream of the drying unit to remove the solvent (ie, DMF) by washing the treated fabric pieces with water.

[0090] When the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, according to a specific embodiment, each extraction chamber is connected to the next extraction chamber in a path for transporting the fabric from the first extraction chamber to the next extraction chamber by a solvent supply means, and the solvent supply means is configured to supply the solution comprising the solvent and extracted substances leaving each extraction chamber to the preceding extraction chamber.

[0091] When the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, according to an embodiment, the last extraction chamber in the series is connected to a fresh solvent storage tank, which is configured to supply fresh solvent to the last extraction chamber.

[0092] When the apparatus comprises a plurality of extraction chambers and a plurality of centrifuges, according to a specific embodiment, the apparatus may further comprise a plurality of storage tanks, each storage tank being arranged with respect to the flow of fabric facing downwards towards the extraction chamber and upwards towards the centrifuge (i.e., between the extraction chamber and the centrifuge), and / or each storage tank being arranged with respect to the centrifuge facing downwards towards the extraction chamber.

[0093] Further aspects and advantages of the present invention will be discussed in more detail with reference to the accompanying drawings, which provide non-limiting examples.

[0094] In the accompanying drawings, solid arrows generally represent the flow of textile material, and dotted arrows generally represent the flow of solvent and / or solution comprising solvent and extracted substances.

[0095] Referring to the exemplary embodiment of Figure 1, fabric waste is collected, pre-processed, and fabric size reduced in a fabric size reduction device 1. For example, the fabric size reduction device 1 may be a cutter suitable for cutting fabric and garments into pieces (i.e., clippings) or a machine suitable for converting fabric and / or garments into fibers. The fabric piece dimensions have been disclosed earlier in this specification: a light blue polyester fabric sample reduced to pieces with at least 90% having dimensions in the range of 2.0-2.5 mm is shown in Figure 4.

[0096] After size reduction pre-treatment the textile material is transferred to extraction chamber 2.

[0097] In extraction chamber 2, the textile material is extracted (treated) with a solvent to provide a solution comprising the solvent and extracted substances (the extracted substances include at least the dye). During step b), the solvent or the solution comprising the solvent and extracted substances is circulated through the textile material by entering and exiting extraction chamber 2. Extraction chamber 2 is kept stationary, i.e., static, during step b). Apart from possible movement imparted by the flow of solvent circulated through static extraction chamber 2 and through the textile, for example by a pump, the textile material contained in extraction chamber 2, e.g., fabric or garment or fiber, is also stationary, i.e., static. Preferably, the textile is maintained stationary. In a preferred embodiment, the textile material is in a compressed state; in this embodiment, the textile is preferably in the form of fibers or fiber tufts, as obtained by a textile opening method via a tearing device, for example, those commercially available from Laroche, Dell'orco & Villani (IT) and Zürzler (DE).

[0098] According to a specific example, the extraction step b) has a duration of 2 to 20 minutes, preferably 5 to 15 minutes, more preferably 7.5 to 12.5 minutes, most preferably 10 minutes.

[0099] According to a specific example, the temperature of the solvent (or solution comprising the solvent and the extracted substances) in the extraction chamber 2 ranges from 80 to 140° C., preferably from 82 to 135° C. If the polyester is not dope dyed, but is dyed, for example, with disperse dyes, the maximum temperature will be about 110° C.

[0100] Advantageously, the conditions of the extraction step b) are adjusted depending on the composition of the textile material to be treated.

[0101] For example, if the textile material is in the form of 100% PET fabric and / or clippings dyed with at least one disperse dye, the solvent is preferably DMF and the temperature of the solvent in extraction chamber 2 is in the range of 85-105°C, preferably about 100°C. For example, if the textile material is in the form of 100% PET fibers dyed with at least one disperse dye, the solvent is preferably DMF and the temperature of the solvent in extraction chamber 2 is in the range of 80-110°C, preferably about 85-105°C. For example, if the textile material comprises at least 90% by weight of polyester fibers and at most 10% by weight of elastane fibers dyed with at least one disperse dye, the solvent is preferably DMF and the temperature of the solvent in extraction chamber 2 is in the range of 85-105°C, preferably about 95°C. For example, if the textile material comprises at least 70% by weight of polyester fibers and at most 30% by weight of cotton fibers or a mixture of cotton fibers and elastane, and the polyester fibers are dyed with at least one disperse dye and the cotton fibers are dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is preferably a mixture of DMF and water (comprising a reducing agent and a base), and the temperature of the solvent in the extraction chamber 2 is in the range of 95-105°C, preferably about 100°C.

[0102] After step a), a solution comprising the solvent and the extracted substances (i.e. at least one extracted dye and optionally extracted polyurethane substances, such as elastane) is obtained together with the treated textile.

[0103] According to the present invention, the solution comprising the solvent and extracted substances is recirculated during step b) by passing it in and out of the extraction chamber 2 while maintaining both the fabric and the extraction chamber 2 in a stationary (i.e. static) state.

[0104] According to a specific embodiment, at the end of step b), the mixture of textile and solvent is transferred to a centrifuge 3 to remove the solution comprising the solvent and extracted substances remaining in the textile according to step c). In a specific embodiment, the centrifugation is carried out in an extraction chamber. For example, if the extraction chamber is a washer or solvent clarifier, the extraction chamber can be subjected to centrifugation and, optionally, washing with solvent, washing with water, and drying. In a specific embodiment, extraction, centrifugation, washing, and drying are carried out in one machine, for example, a solvent clarifier; the same machine can further comprise a distillation unit.

[0105] In a specific example, the solvent not absorbed by the fabric is removed from the extraction chamber 2 and provided to a solvent storage tank 9. The solvent storage tank 9 is further configured to receive the solvent removed from at least the centrifuge 3 and, optionally, the drying device 4. The solvent in the solvent storage tank 9 is typically a solution of the solvent and the extracted substances. The solvent (or the solution comprising the solvent and the extracted substances) is provided from the solvent storage tank 9 to the extraction chamber 2.

[0106] According to a specific embodiment, the centrifugation is carried out at a force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for example 1200, for a time in the range of 0.5 to 10 minutes, preferably 1 to 5 minutes. In a specific embodiment, after centrifugation, the solution of solvent and extracted substances is returned to the extraction chamber 2 for processing another batch of textile material, i.e. a new batch of textile material.

[0107] In a specific example, after centrifugation, the textile material may be washed in centrifuge 3. The washing is carried out, for example, using fresh solvent or a fresh mixture of solvent, water, reducing agent, and base, depending on the material to be washed. Fresh solvent or a fresh mixture of solvent, water, reducing agent, and base is supplied to centrifuge 3 by fresh solvent tank 6. The temperature of the clean solvent in the centrifuge during the washing process is in the range of 80-110°C, preferably 85-105°C, for polyester fibers, and in the range of 85-110°C, preferably about 95°C. The washed material is centrifuged to remove the solvent used for washing. The solvent or mixture of solvent, water, reducing agent, and base is recovered and preferably supplied to extraction chamber 2 for processing another batch of textile material.

[0108] According to FIG. 1, after centrifugation the textile material is dried in a drying device 4 .

[0109] When the extracted materials in the solution comprising the solvent and extracted materials reach a concentration at which further dye extraction is impaired, the solution comprising the solvent and extracted materials is fed from the extraction chamber 2 and / or centrifuge to a distillation apparatus 5, which separates the solvent from the extracted materials. The distilled solvent is then transferred to a fresh solvent tank 6 for storage. When required, fresh solvent is fed from the fresh solvent tank 6 to at least the extraction chamber 2, for example, to adjust the fabric:solvent bath ratio. As described above, fresh solvent can be fed from the fresh solvent tank 6 to the centrifuge 3 to perform the washing of the textile.

[0110] In one embodiment, the textile material is selected from polyester fibers, fabrics made of polyester fibers, cloth clippings made of polyester fibers, and polyester fibers ground to polyester powder, at least a portion of the polyester fibers are dyed with at least one disperse dye, the solvent is DMF, and the temperature of the solvent or the solution comprising the solvent and the extracted substance in the extraction chamber is in the range of 80-110°C, preferably 85-105°C, for polyester fibers, and in the range of 85-110°C, preferably about 95°C, for fabrics, cloth clippings, and polyester powder.

[0111] In one embodiment, the textile material comprises at least 90% by weight of polyester fibers and at most 10% by weight of elastane fibers, wherein at least some of the polyester fibers are dyed with at least one disperse dye, the solvent is DMF, and the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber and preferably in the washing step in the centrifuge after the first centrifugation is in the range of 85-105°C, preferably about 95°C.

[0112] In one embodiment, the textile material comprises at least 50%, preferably 70%, by weight of polyester fibers and at most 50%, preferably 30%, by weight of cotton fibers, wherein at least a portion of the polyester fibers are dyed with at least one disperse dye and at least a portion of the cotton fibers are dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes, and sulfur dyes, the solvent is a mixture of DMF and water (comprising at least one base and optionally at least one reducing agent), and the temperature of the solvent or the solution comprising the solvent and the extracted substances in the extraction chamber and preferably in the washing step in the centrifuge after the first centrifugation is in the range of 85-110°C, preferably about 95°C.

[0113] FIG. 2 shows a schematic diagram of an embodiment of the method and apparatus of the present invention, which includes two extraction chambers (2a and 2b) and two centrifuges.

[0114] Referring to the non-limiting example of Figure 2, in a textile size reduction apparatus 1, textile waste is collected and pre-treated for textile size reduction. After size reduction pre-treatment, the textile material is transferred to a first extraction chamber 2a. In extraction chamber 2a, the textile material is extracted (treated) with a solvent to provide a solution comprising the solvent and extracted substances (wherein the extracted substances include at least one dye). Preferably, when the apparatus comprises one or more extraction chambers, the solvent used in the first extraction chamber is the solution comprising the solvent and extracted substances obtained in the second extraction chamber after the second extraction step b) performed on the previous processed textile batch. The solution comprising the solvent and extracted substances is circulated in and out of the first extraction chamber 2a during step b), while both the textile and extraction chamber 2a are maintained in a stationary (i.e., static) state.

[0115] According to a specific embodiment, at the end of step b), the textile is transferred from the first extraction chamber 2a to a first centrifuge 3a in order to remove the solution comprising the solvent and extracted substances remaining in the textile according to step c). According to a specific embodiment, the centrifugation is carried out at a G-force in the range of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for a time in the range of 0.5 to 10 minutes, preferably 1 to 5 minutes. According to a specific embodiment, after centrifugation, the solution comprising the solvent and extracted substances is returned to the extraction chamber 2 for processing another batch of textile material.

[0116] After centrifugation, the textile material is transferred from the first centrifuge 3a to the second extraction chamber 2b. In the second extraction chamber 2b, the textile material is further extracted (treated) with a solvent to provide a solution comprising the solvent and extracted substances (the extracted substances include at least one dye). Preferably, if the apparatus comprises more than one extraction chamber, the solvent used in the second extraction chamber may be fresh solvent. The textile material is maintained in a static state within the extraction chamber 2b for the entire duration of the extraction process.

[0117] 1, and referring to FIG. 2, in an embodiment, solvent not captured by the fabric is recovered from extraction chambers 2a and 2b and supplied to at least one solvent storage tank (not shown). The at least one solvent storage tank is further configured to receive solvent removed from at least centrifuges 3a and 3b and, optionally, from drying device 4. The solvent in the solvent storage tanks is generally a solution comprising the solvent and the extracted substances. The solvent (or solution comprising the solvent and the extracted substances) is supplied from the at least one solvent storage tank to extraction chambers 2a and 2b.

[0118] In a specific example, in a multi-extraction method, fresh solvent is supplied to all extraction chambers at the start of the method (i.e., to process the first batch of textile waste), and the solvent is reused in the same extractor until saturation, i.e., a concentration condition in the solvent at which further solvent extraction becomes impaired, e.g., after at least 20, preferably at least 30, more preferably at least 40, e.g., 50, extraction batches, is reached. When starting with the second batch of textile waste to be treated, fresh solvent is supplied only to the last extraction chamber.

[0119] As with extraction chamber 2, the resulting solution comprising solvent and extracted substances is recirculated in and out of second extraction chamber 2b during step b), while both the fabric and extraction chamber 2b are maintained in a static (i.e., stationary) state.

[0120] At the end of step b), the textile is transferred from the second extraction chamber 2b to a second centrifuge 3b in order to remove the solution comprising the solvent and extracted substances remaining in the textile according to step c). In a specific example, after centrifugation, the solution of solvent and extracted substances is returned to the extraction chamber 2b for processing another batch of textile material.

[0121] Preferably, the solution comprising the solvent and extracted substances obtained in the second extraction chamber 2b after one or more extraction steps is fed to the first extraction chamber 2a for extracting another batch of textile.

[0122] In a specific example, after centrifugation in the second centrifuge 3b, the textile material may be washed in the second centrifuge 3b. The washed material is centrifuged to remove the solvent used for washing. The solvent, or a mixture of solvent, water, reducing agent, and base, is recovered and preferably transferred to the second extraction chamber 2b for processing another batch of textile material.

[0123] According to FIG. 2, after centrifugation in the second centrifuge 3 b the textile material is dried in a drying device 4 .

[0124] When the extracted materials in the solution comprising the solvent and extracted materials reach a concentration such that the solvent is saturated and further dye extraction is impaired, the solution comprising the solvent and extracted materials is fed to a distillation apparatus 5, which separates the solvent from the extracted materials. The distilled solvent is then transferred to a fresh solvent tank 6 for storage. If required, fresh solvent is fed from the fresh solvent tank 6 to at least the second extraction chamber 2b, for example to adjust the fabric:solvent bath ratio. As mentioned above, fresh solvent can be fed from the fresh solvent tank 6 to a second centrifuge 3b to wash the textile. Optionally, fresh solvent can be fed from the fresh solvent tank 6 to a first centrifuge 3a to wash the textile.

[0125] FIG. 3 shows a schematic diagram of an embodiment of the method including multiple (four) extraction chambers and multiple (four) centrifuges.

[0126] 3 shows a plurality of storage tanks, specifically a plurality of first storage tanks 7a, 7b, 7c, 7d and a plurality of second storage tanks 8a, 8b, 8c, 8d, one first storage tank 7a, 7b, 7c, 7d is provided after each extraction chamber 2a, 2b, 2c, 2d, and one second storage tank 8a, 8b, 8c, 8d is provided after each centrifuge 3a, 3b, 3c, 3d.

[0127] According to a specific example, the textile material obtained in step b), i.e., the textile material after extraction with the solvent, can be transferred from the extraction chambers 2a, 2b, 2c, 2d to the first storage tanks 7a, 7b, 7c, 7d, for example, when the centrifuges 3a, 3b, 3c, 3d cannot hold the entire amount of textile material to be processed in the reaction chambers 2a, 2b, 2c, 2d, the textile material obtained in step b) can be transferred from the extraction chambers 2a, 2b, 2c, 2d to the first storage tanks 7a, 7b, 7c, 7d, so that a further batch of textile material can be extracted in the extraction chambers 2a, 2b, 2c, 2d and at the same time the centrifugation of the textile material obtained in step b) can be completed.

[0128] In the embodiment of Figure 3, the textile material leaving the centrifuges 3a, 3b, 3c, 3d is transferred to second storage tanks 8a, 8b, 8c, 8d. The material in the first three second storage tanks 8a, 8b, 8c is then fed to the subsequent extraction chambers (i.e., extraction chambers 2b, 2c, 2d) for further extraction. The textile material in the last second storage tank 8d is free or substantially free of dyes and possible polyurethanes and is subjected to drying.

[0129] The resulting solution comprising the solvent and extracted substances in each extraction chamber is recirculated in and out of that extraction chamber during step b), while both the fabric and the extraction chamber are maintained in a stationary (i.e. static) state.

[0130] In a specific example, after centrifugation, the solution of solvent and extracted substances is returned to the preceding extraction chamber for processing another batch of textile material. For example, referring to Figure 3, the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3a is returned to extraction chamber 2a, the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3b is returned to extraction chamber 2b, the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3c is returned to extraction chamber 2c, and the solution of solvent and extracted substances obtained after centrifugation in centrifuge 3d is returned to extraction chamber 2d.

[0131] According to the embodiment of FIG. 3, the solvent used in the last extraction chamber 2d may be fresh solvent. After extraction, a solution containing the solvent and extracted substances is obtained. In particular, after the solvent used in the first extraction chamber 2a, i.e., the solution containing the solvent and extracted substances, reaches a concentration such that further dye extraction is impaired, and the solution containing the solvent and extracted substances is transferred from the first extraction chamber 2a to a distillation apparatus, the solution containing the solvent and extracted substances obtained in the last (fourth) extraction chamber 2d may be supplied to the preceding (third) extraction chamber 2c for the third extraction step of the next textile batch. The solution containing the solvent and extracted substances obtained in the third extraction chamber 2c may be supplied to the preceding (second) extraction chamber 2b for the second extraction step of the next textile batch. The solution containing the solvent and extracted substances obtained in the second extraction chamber 2b may be supplied to the preceding (first) extraction chamber 2a for the first extraction step of the next textile batch. Advantageously, the amount of dye in the textile gradually decreases from the first extraction chamber 2a to the last extraction chamber 2d, while the concentration of the extracted substances, in particular the dye, in the solvent used in the extraction step (i.e., the solution comprising the solvent and the extracted substances) decreases from the first extraction chamber 2a to the last extraction chamber 2d. In other words, the solution comprising the solvent and the extracted substances obtained in the last (fourth) extraction chamber 2d is sent to the third extraction chamber 2c for the third extraction step of the next textile batch, after which the solvent used in the first extraction chamber 2a is sent to a distillation apparatus, and the solvent used in the second extraction chamber 2b is sent to the first extraction chamber 2a, and the solvent used in the third extraction chamber 2c is sent to the second extraction chamber 2b.

[0132] Figures 4 and 5 visually show the reduction in dye content from the initial polyester material of reduced size (Figure 4) to the same material at the end of the process (Figure 5).

[0133] The present invention will now be further described with reference to the following non-limiting examples. [Example]

[0134] 1.5 kg of waste textile fabric (90% PET (dyed with disperse dyes) and 10% cotton (dyed with reactive dyes)) was placed in an extraction chamber. 15 L of solvent (DMF) was added to the extraction chamber and heated to 90-95°C. After 10 minutes of extraction with the circulating solvent, the textile was directly transferred to a centrifuge where the solvent was removed at 1200 G-force for 2-3 minutes. The textile was then transferred to a second extractor where 15 L of a DMF-water mixture was poured in the presence of a reducing agent (NaSO) and a base (NaOH) and the reactive dye was removed at 90-95°C for 10 minutes. The second centrifugation process was followed by a drying process at 80-90°C. The solvent was collected again and reused. [Example]

[0135] 1.5 kg of waste textile fabric (90% PET (dyed with disperse dyes) and 10% cotton (dyed with reactive dyes)) was placed in an extraction chamber. 15 L of DMF-water (in the presence of a reducing agent and base) was added to the extraction chamber and heated to 90-95°C. After 10 minutes of extraction with the circulating solvent, the textile was directly transferred to a centrifuge and centrifuged at 1200 G-force for 2-3 minutes to remove the solvent. The textile was then transferred to a second extraction chamber, where 15 L of DMF was poured and centrifuged at 90-95°C for 10 minutes to remove the dye. The second centrifugation process was followed by a drying process at 80-90°C. The solvent was collected again and reused.

[0136] The claimed method and device thus make it possible to remove dyes from textile waste, in particular disperse dyes from polyester fibres and vat, reactive, pigment, direct and sulphur dyes from cotton fibres. The resulting textiles are then recycled in a manner known per se. [Explanation of symbols]

[0137] (1) Fabric size reduction device (2) Extraction chamber (2a) First extraction chamber (2b) Second extraction chamber (2c) Third extraction chamber (2d) Fourth extraction chamber (3) Centrifuge (3a) First Centrifuge (3b) Second centrifuge (3a) No. 3 Centrifuge (3b) No. 4 centrifuge (4) Drying equipment (5) Distillation apparatus (6) Fresh solvent tank (7a)~(7c) First storage tank (8a)~(8b) Second storage tank

Claims

1. 1. A method for removing dyes from textile materials, in particular textile waste, the textile materials comprising at least 50%, preferably at least 60%, more preferably at least 70% by weight of polyester fibres, said method comprising the following steps: a) providing a batch of textile material in an extraction chamber; b) extracting the textile batch with a solvent to provide a solution comprising the solvent and extracted substances, the extracted substances including at least the dye, wherein the solvent is maintained stationary and the solvent is circulated through the textile and the extraction chamber; c) removing the solution comprising the solvent and extracted materials from the fabric. wherein the solution comprising the solvent and the extracted substances obtained in steps b) and / or c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are preferably repeated for a predetermined number of cycles or until the amount of extracted substances in the solution comprising the solvent and the extracted substances reaches a concentration at which further dye extraction is impaired.

2. 2. The method of claim 1, wherein at least a portion of the polyester is dyed, preferably dyed or dope dyed with at least one disperse dye, and the textile material is selected from fibers, fiber tufts, filaments, yarns, fabrics, fabric clippings, garments, garment clippings, and mixtures thereof, and preferably the fiber waste is compressed in an extraction chamber or in a basket contained in the extraction chamber.

3. 2. The method of claim 1, wherein step c) comprises separating the solution comprising the solvent and the extracted substances from the textile by centrifugation, wherein step c) is carried out in a centrifuge, the extraction chamber preferably being configured to operate as a centrifuge.

4. 4. The method according to claim 3, wherein after step c), a solvent, preferably fresh solvent, is supplied to the centrifuged textile present in the centrifuge, and a step of solvent washing of the textile is carried out in the centrifuge to remove the dye from the centrifuged textile.

5. 2. The method according to claim 1, wherein the extraction chamber is a first extraction chamber, and wherein after the first extraction step b), the textile material is fed from the first extraction chamber to a first centrifuge for the first removal step c), from the first centrifuge to a second extraction chamber for the second extraction step b), and from the second extraction chamber to a second centrifuge for the second extraction step c), so that the first and second extraction steps b) and the removal step c) are carried out in two different extraction chambers and two different centrifuges, respectively.

6. 6. The method according to claim 5, wherein the solvent removed from the second extraction chamber and / or the second centrifuge, preferably from the second extraction chamber, is fed to the first extraction chamber.

7. 2. The method of claim 1, wherein steps b) and c) are repeated two or more times in two or more extraction chambers and centrifuges, and the solvent removed from any extraction chamber different from the first chamber is supplied to the preceding extraction chamber, and the solvent used in step b) is in the form of a solution comprising the solvent and the extracted substance, and the extracted substance is at least one dye.

8. 2. The method according to claim 1, wherein the solvent is DMF or DMAC or a mixture of DMF or DMAC with alkaline water or a mixture thereof, and preferably the temperature of the solvent or the solution comprising the solvent and the extracted substance in the extraction chamber is in the range of 80 to 140°C, preferably 82 to 135°C, more preferably 82 to 110°C.

9. 2. The method according to claim 1, wherein the liquor ratio of fabric to solvent (kg / L) is in the range of 1 / 3 to 1 / 20, preferably 1 / 3.5 to 1 / 12, more preferably 1 / 4 to 1 / 10.

10. 2. The method of claim 1, wherein step c) is carried out in a centrifuge at a G-force of 250 to 5000, preferably 800 to 2000, more preferably 900 to 1300, for a time of 0.5 to 10 minutes, preferably 1 to 5 minutes.

11. 2. The method according to claim 1, wherein the textile comprises polyester fibres and further comprises at least one polyurethane material, preferably elastane; preferably the textile material comprises at least 90% by weight of polyester fibres and at most 10% by weight of elastane fibres; at least a portion of the polyester fibres are dyed with at least one disperse dye, the solvent is DMF, and the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber is in the range of 85 to 105°C, preferably 95°C.

12. 2. The method according to claim 1, wherein the textile comprises polyester fibres and further comprises at least one cellulosic material, preferably cotton, more preferably cotton fibres, the textile material preferably comprises at least 50%, preferably 70%, by weight of polyester fibres and at most 50%, preferably 30%, by weight of cotton fibres, at least a portion of the polyester fibres have been dyed with at least one disperse dye, and at least a portion of the cotton fibres have been dyed with at least one dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulphur dyes, the solvent is a mixture of DMF and water (comprising at least one base and optionally at least one reducing agent), and the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber and optionally throughout the process is in the range of 85 to 110°C, preferably about 95°C.

13. 2. The method according to claim 1, wherein the textile comprises polyester fibres and further comprises at least one polyurethane material, preferably elastane and at least one cellulose material, preferably cotton, more preferably cotton fibres, the textile material preferably comprises at least 50%, preferably 70%, by weight of polyester fibres and at most 50%, preferably 30%, by weight of cotton fibres and elastane fibres, at least a portion of the polyester fibres have been dyed with at least one disperse dye, and at least a portion of the cotton fibres have been dyed with a dye selected from vat dyes, reactive dyes, pigments, direct dyes and sulphur dyes, the solvent is a mixture of DMF and water (comprising at least one base and optionally at least one reducing agent), and the temperature of the solvent or of the solution comprising the solvent and the extracted substances in the extraction chamber and optionally in the washing step is in the range of 95 to 105°C, preferably about 100°C.

14. 2. The method according to claim 1, wherein the solution obtained in step b) and / or c) is used as a solvent for extracting dye from another batch of textile material, and steps b) and c) are repeated up to 20 times, preferably up to 40 times, more preferably up to 60 times using the solution as solvent.

15. 10. An apparatus for removing dyes from textiles, preferably fabrics, according to the method of claim 1, comprising at least one extraction chamber (2) configured to treat the textile material with a solvent, pumping or circulating means (P) for circulating the solvent through the extraction chamber (2) and the textile waste, at least one centrifuge (3) for separating a solution comprising the solvent and extracted substances from the textile material, at least one fresh solvent storage tank (6) and at least one distillation device (5), the fresh solvent storage tank (6) configured to supply fresh solvent to the extraction chamber, and the distillation device (5) configured to receive the solution comprising the solvent and extracted substances from the extraction chamber (2) and / or the centrifuge (3) to separate the extracted substances from the solvent; and optionally at least one storage tank (7a-7d) configured to receive the textile material from the extraction chamber (2) and to supply the textile material to the centrifuge; preferably, the extraction chamber (2) is configured to operate as the centrifuge (3).

16. 16. Apparatus according to claim 15, comprising a plurality of extraction chambers (2a-2d) and a plurality of centrifuges (3a-3d), wherein the extraction chambers and centrifuges are arranged in series, means for feeding the textile along the series of extraction chambers and centrifuges to provide a textile flow, wherein at least one centrifuge is connected, directly or indirectly, to an extraction chamber (2) above in relation to the textile flow and to another extraction chamber below in relation to the textile flow, preferably each extraction chamber being connected to the preceding extraction chamber by a solvent supply means.

17. 17. The apparatus according to claim 15 or 16, wherein each extraction chamber is connected to the preceding extraction chamber by a solvent supply means configured to supply a solution comprising solvent and extracted substances exiting each extraction chamber to the preceding extraction chamber, and only the last extraction chamber in the series is connected to a fresh solvent storage tank, which is configured to supply solvent only to the last extraction chamber.

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