Method and apparatus for recycling textiles

Abstract

A method of treating a waste blended textile comprising polyester fibers and cotton fibers, the method depolymerizing the polyester in a controlled environment to obtain a treated textile comprising cotton staple fibers, suitable for recovery to form cotton yarns.

Description

Technical Field

[0001] The present invention relates to a method and apparatus for recycling textiles. More specifically, the present invention relates to a method for recycling textiles containing cellulose staple fibers and polyester. The method can remove polyester from polyester blended textiles, i.e., textiles such as fabrics, garments, yarns and fibers containing polyester filaments or polyester fibers and cellulose staple fibers (especially cotton staple fibers), and recover and recycle the cellulose staple fibers.

[0002] The cotton fibers and cellulose fibers recovered according to the method are suitable for use as staple fibers for yarn production without the need for dissolution and regeneration into man-made cellulose fibers. Technical Background

[0003] Recycling of textile waste, especially fabrics and used clothing and apparel, has become a major goal of the textile industry. Textile waste includes pre-consumer textiles, such as waste fabrics and yarns or filaments obtained during the production of fabrics, clothing and yarns, defective fabrics, and post-consumer textiles, such as waste or defective clothing and upholstery fabrics. New and efficient methods for recycling textile waste are currently being actively researched.

[0004] One of the objects of the present invention is to recycle and recycle cellulose fibers, in particular cotton fibers in yarns, and to recover polyester in blended textiles and textiles (i.e., fabrics and textiles commonly referred to as poly-cotton or polyester-cotton fabrics) as the corresponding monomer. Poly-cotton fabrics include yarns containing cellulose staple fibers and polyester filaments or fibers. Blended textiles as defined in the present application may include yarns containing cotton yarns and polyester yarns and / or cotton yarns that do not contain polyester and polyester yarns that do not contain cotton fibers. These yarns are woven or knitted into a fabric structure. Garments processed according to the present invention may also include non-woven elements, typically made of metal or plastic materials, such as zippers, rivets, labels, etc.

[0005] Methods for recycling polyester-containing fabrics are well known in the art. Some methods involve depolymerizing the polyester component of the fabric to obtain the starting monomers terephthalic acid (TPA) and ethylene glycol (EG). Such known recycling methods require pre-cutting or shredding of the fabric before treating the fabric with the depolymerization solution. The final products include cellulose pulp, TPA and EG; the TPA and EG can be used to produce polyester or for other purposes.

[0006] WO 2019 / 140245 discloses a method and system for recycling polycotton fabrics, wherein shredded fabrics are treated in an aqueous solution with a pH value of 10-14 under subcritical conditions, at a temperature of 105°C to 190°C, a pressure of 40 to 300 psi, and a time of 0 to 90 minutes. The polyester component is depolymerized into TPA and EG, and the cotton fiber is degraded into cellulose pulp, which is then recovered into man-made cellulose fibers, i.e., regenerated cellulose materials, including rayon, viscose, lyocell or cellulose acetate through additional processing.

[0007] The known methods have the disadvantage of involving expensive and time-consuming steps, such as shredding the fabric before the depolymerization step and processing the cellulose pulp obtained at the end of the depolymerization step, in order to obtain usable regenerated cellulose fibers after dissolution of the pulp and several additional processing steps. In particular, as discussed in the experimental part of the present application, the method of WO2019 / 140245 leads to a significant loss of degree of polymerization (DP loss) of the cotton fibers; this loss has a negative impact on the possibility of recovering the cotton fibers in cotton yarn using known mechanical processes. In addition, referring to Examples 7-8 of WO2019 / 140245, WO 2019 / 140245 teaches that the complete depolymerization of polyester in a small portion of poly-cotton fabric requires the use of a catalyst, a process that results in a solution containing the catalyst that is very difficult to handle or recover, or requires the use of MeOH as a co-solvent, which results in a sharp loss of DP in the cotton fibers of the fabric after the depolymerization of the polyester.

[0008] Another problem is that, for example according to the teachings of WO2019 / 140245, known garment recycling processes only allow for the recycling of parts of garments, since parts of garments with zippers, rivets, labels, buttons and similar elements are cut out of the garments before the garments are processed. As an example, the upper part of jeans containing rivets and zippers is removed from the garment, so that only the leg part is recycled. This step results in a lower percentage of garment fabric being recycled and incurs additional processing costs.

[0009] Therefore, an object of the present invention is to address the above-mentioned deficiencies in known methods of recycling polyester-cotton textiles and to provide a recycling method which provides a safe, low-cost, simple and environmentally clean method for recycling waste polyester-cotton textiles, fabrics, garments, yarns and fibers by recycling cotton (or cellulose) fibers in a state suitable for use in yarn production, i.e. as staple fibers. In other words, an object of the present invention is to mechanically recycle cotton fibers into yarn.

[0010] Another object of the present invention is to avoid the step of treating the cellulose pulp obtained from cotton (or cellulose) staple fibers from waste polyester-cotton fabrics.Another object of the present invention is to recycle garments without the need to previously remove zippers and similar non-woven elements. Summary of the invention

[0011] The above objects of the invention are achieved by the method means of independent claims 1 and 17, and by the apparatus of independent claim 15. Textiles obtainable by the method of the invention are the subject matter of claims 20 and 21. Preferred aspects of the invention are recited in the respective dependent claims.

[0012] The method relates to the recycling of waste "blended textiles", i.e. textiles comprising polyester and cotton, such as so-called "poly-cotton" textiles, or textiles comprising polyester and other cellulosic fibers different from cotton. Typically, the polyester is in the form of filaments; it can also be in the form of polyester staple fibers, for example, in yarn. The polyester can also be in the form of sewing yarns for sewing together parts of a garment to be treated. In view of the aim of the present invention to recover the valuable cotton content in a reusable form, preferably, the amount of polyester in the textile according to the invention is from 1% to 60% by weight of the weight of the textile, more preferably, the amount of polyester is from 4% to 50% by weight.

[0013] In one embodiment of the invention, the method is intended to recycle garments in the form of "one-piece garments"; the term "one-piece" garment is used herein to define a garment containing non-textile elements, such as buttons, rivets, zippers, etc., as described above. The method for recycling garments relates to garments made of or containing blended textiles, and also to garments in which the fabric is made of 100% cotton or cellulose fibers, and the polyester is present only as a sewing thread or yarn, used to sew the parts of the garment together.

[0014] The applicant has found that by applying the method / process of the present invention to clothing with polyester sewing thread, the sewing thread can be dissolved so that the treated clothing becomes the part of separation. The part of separation obtained after the process includes, for example, in jeans, trousers, including pocket parts, leg parts and non-textile parts (such as buttons, zippers, rivets, etc.) that are also separated from clothing at the end of the process. Therefore, after the process of the present invention, the non-textile parts can be removed from the treated clothing to obtain a plurality of treated clothing parts made of the fabric composed of cotton fiber (or cellulose fiber). The cotton fabric thus obtained can therefore be processed into loose cotton fibers in a manner known per se in the art, which is suitable for being recycled into cotton yarn by spinning and similar processes.

[0015] The term "textile" refers to fabric, clothing, yarn and fiber here. Fabric can be woven fabric, knitted fabric and nonwoven fabric. Clothing includes any clothing items, such as T-shirts, pants, jeans, jackets, shirts, sportswear, etc. In some embodiments, clothing can be used as is for the method, that is, clothing can include non-woven elements, such as zippers, rivets, buttons (these elements are usually made of metal or plastic) and labels. Exemplary poly-cotton yarn is a core-spun yarn, which has a polyester core and a cotton sheath comprising cotton staple fibers. Non-woven blended textiles can include non-woven polyester filaments on cotton or cellulose substrates.

[0016] The term "cellulose fibers" herein defines cotton fibers, cotton derivative fibers, modified cotton fibers, and other fibers commonly used in yarns, such as linen fibers, flax fibers, jute fibers, hemp fibers, ramie fibers, kenaf fibers, sisal fibers, henna fibers, and similar fibers. The cotton and cellulose fibers in the textiles to be recycled are generally in the form of staple fibers in the yarn. Viscose fibers and other man-made cellulose-based fibers fall within the definition of cellulose fibers of the present application. In both cases, the cotton fibers or cellulose fibers are recycled as is (e.g., in the original form of staple fibers of the yarn), rather than becoming pulp. For example, a polycotton core-spun yarn is made of a cotton sheath and a polyester core, which is treated according to the method of the present invention, and will ultimately result in a yarn in which only the sheath is present at the end of the method, while the polyester has been depolymerized and dissolved into the disodium salt of TPA and EG during the method.

[0017] The term "bath ratio" is intended to define the ratio between the dry weight of the textile to be recycled and the weight of the solution, wherein the solution is a depolymerization solution according to the stage of the process of the invention, or a bleaching solution or a washing solution used in the further steps of the process as described in the following description.

[0018] The terms "dissolve" or "dissolve out" when referring to polyesters are intended to define the result of depolymerization of the polyester into its monomers, whereby, following the process of the invention, substantially no polyester filaments or fibers are present in the treated textile.

[0019] The term "circulation" when referring to the depolymerization solution is intended to define a flow that the solution undergoes, forced through the textile and through the reaction chamber containing the textile. The flow is preferably generated by a pump that feeds the solution into the reaction chamber and through the textile and the reaction chamber. The solution leaves the reaction chamber and is subsequently fed back to the reaction chamber to circulate again through the textile and the reaction chamber. The bleaching and washing solutions are also circulated several times through the textile in the same way as the depolymerization solution. The apparatus for carrying out the method of the invention comprises a fluid circuit, which generally comprises an inlet and an outlet for the reaction chamber.

[0020] The textile is held in a reaction chamber in a stationary (i.e. static) state. The term "stationary" or "static" state is intended to define that the fabric is contained in the reaction chamber and is held there while the depolymerization solution (or bleaching solution or washing solution) is fed through the textile. The textiles fill the reaction chamber so that they do not move with the solution, i.e., they are not displaced by the flow of the solution. In a preferred embodiment, the textiles are compressed in the reaction chamber. The fact that the textiles fill the chamber - they may be pressed or compressed into the chamber - also provides the advantage of greatly improving the productivity of the method. In other words, an embodiment in which the textiles are stirred or moved in the depolymerization solution is not an embodiment of the present invention, for example, by means of a drum in a washing machine.

[0021] In particular, the present invention relates to a method for recycling waste blended textiles comprising polyester and cellulose fibers, preferably cotton fibers, the method comprising depolymerizing the polyester in an alkaline aqueous solution, comprising the following steps:

[0022] a) providing a quantity of the textile in a reaction chamber;

[0023] b) providing an amount of the alkaline depolymerization solution according to a bath ratio of the textile weight to the solution weight in the range of 1 / 2 to 1 / 20;

[0024] c) circulating the amount of depolymerization solution through the textile to depolymerize the polyester into corresponding monomers, and removing the polyester monomers from the textile;

[0025] d) removing the depolymerization solution from the reaction chamber;

[0026] wherein, in step c), the temperature of the depolymerization solution is in the range of 101°C to 160°C, and wherein

[0027] e) the textile is in a resting (ie static) state and the solution is circulated through the textile to provide a treated textile substantially free of polyester material, which comprises cellulosic staple fibers, preferably cotton staple fibers.

[0028] Advantageously, in the process, a depolymerization solution is fed to the chamber so that the polyester fibers of the waste blended textiles maintained in a static state within the reaction chamber are depolymerized under reaction conditions that allow the ester bonds of the polyester to be cleaved into its monomers terephthalic acid (as disodium salt (Na2TP)) and ethylene glycol (EG) and significantly reduce the modification and depolymerization of the cellulose staple fibers.

[0029] As in Figure 1 , 27 and as explained below, a flow of depolymerization solution is fed into the chamber, it leaves the chamber through the textile and returns to the chamber again and passes through the textile several times, so that the polyester present in the textile is depolymerized. The number of times the solution is fed through the textile, i.e. the number of cycles, can be adjusted according to the amount of polyester in the textile to be treated. Advantageously, the number of times the depolymerization solution is fed through the textile or the number of cycles is in the range of 30 to 480 cycles / hour, preferably 50 to 400 cycles / hour, more preferably 60 to 300 cycles / hour, most preferably 70 to 200 cycles / hour.

[0030] Advantageously, the temperature of the depolymerization solution, and thereby the pressure, is increased in the closed chamber to a value such that the polyester filaments or fibers are depolymerized, but degradation or modification (e.g., reduction in degree of polymerization) of the cellulosic fibers (e.g., cotton staple fibers) is minimized and possibly avoided.

[0031] Advantageously, in step c), a selected amount of depolymerization solution is circulated at the claimed temperature, for example, by a pump in the chamber, and circulated through the fabric throughout the length of step c) of the process. In other words, the waste mixed textile is maintained in a substantially static state, and the waste mixed textile is contacted with the depolymerization solution several times by repeatedly passing the depolymerization solution through (i.e. circulating) the fabric) to increase the content of disodium terephthalate (Na2TP) or terephthalate ions or EG in the solution, or more generally, to increase the content of products from degraded polyester in the solution, while maintaining the cotton or cellulose fibers intact as much as possible. It was found that the combination of keeping the textile in a static or static state and circulating (i.e. flowing) the depolymerization solution through the textile allows complete depolymerization of the polyester to be achieved, while greatly reducing the depolymerization of the cotton fabric.

[0032] Advantageously, the technical effect of circulating (i.e. flowing) the depolymerization solution under mild conditions through a static (i.e. standing) textile product is to protect the cellulose polymer chains from degradation, and to recover cotton fibers and cellulose fibers suitable for processing into recycled yarn in a manner known in the art, for example, mechanically treating the yarn to recover fibers that will be spun into new yarn.

[0033] Advantageously, at the end of the process, the polyester fibers / filaments have been removed (by depolymerization) from the treated fabric, which comprises cotton or other cellulose fibers and is substantially free of polyester degradation products, in particular Na2TP, TPA and ethylene glycol (EG). The treated textile obtained by the process of the invention comprises cotton / cellulose fibers, typically in the form of yarn, which can be subjected to a cotton yarn recycling process in a manner known in the art. The cotton fibers thus obtained can be used in a spinning process that can be adjusted according to the degree of polymerization of the cellulose.

[0034] Advantageously, if the treated textile is a garment comprising non-textiles, such as metal (or plastic) parts (e.g. buttons, rivets, zippers), according to the method of the invention, the polyester sewing yarns sewing the parts of the garment together are depolymerized so that the metal or plastic elements are detached from the garment and can be removed from the garment and possibly recycled.

[0035] Advantageously, garments made from fabrics consisting of cotton yarn (100% cotton) after treatment according to the method of the invention will provide a valuable source of cotton fibers which still offer very good mechanical properties.

[0036] According to one aspect, the depolymerization solution is an alkaline solution, preferably an alkaline solution comprising sodium hydroxide or potassium hydroxide. The solution preferably contains 70 g / L to 500 g / L, more preferably 76 to 120 g / L of a sodium hydroxide solution having a Baumé degree equal to 48° Be. In other words, the NaOH concentration in the depolymerization solution is in the range of 33 g / L to 237 g / L of NaOH, preferably 36 g / L to 57 g / L of NaOH.

[0037] According to one possible aspect, the amount of depolymerization solution to be used in the method is selected according to the amount of textile to be treated. In some embodiments, the bath ratio is in the range of 1 / 2 to 1 / 20, preferably 1 / 2 to 1 / 15, most preferably 1 / 5 to 1 / 8; the bath ratio is the weight ratio between the weight of the textile to be treated and the weight of the depolymerization solution.

[0038] According to a feasible aspect, in step c), the temperature of the depolymerization solution is in the range between 101° C. and 160° C., preferably in the range of 120° C. to 160° C. Advantageously, the temperature of the depolymerization solution is in the range between 130° C. and 140° C.; the claimed range minimizes changes in the chemical and mechanical properties of the cotton or cellulose fibers, such as the length and size of the fibers, the degree of polymerization of the cellulose.

[0039] According to one possible aspect, during step c), the pressure in the chamber is in the range of 1.05 bar (0.05 bar) to 7.0 bar (6.0 bar), preferably 2.7 bar (1.7 bar) to 7 bar (6 bar), more preferably 2.7 bar (1.7 bar) to 5.5 bar (4.5 bar).

[0040] According to one possible aspect, the depolymerization in step c) is carried out for a period of 91 to 240 minutes, preferably 100 to 150 minutes, more preferably 120 minutes.

[0041] In a preferred embodiment, process step c) is carried out at 130° C. for 120 minutes, preferably at a pressure in the range of 2.7 bar (39.16 psi) to 5.5 bar (79.77 psi).

[0042] Advantageously, the bath ratio is such that when the solution is circulated through the chamber and the static textile for the time claimed, the polyester fibers are completely or substantially completely depolymerized, at the claimed bath temperature and pressure. Preferably, the direction along which the solution is circulated through the reaction chamber may be one flow direction, preferably from the center of the chamber to the sides, or the flow direction may be varied during the depolymerization process so that the flow directed from the center of the chamber to the peripheral wall alternates with the flow directed from the peripheral wall of the chamber to the center. After the time, the depolymerization solution is cooled to a temperature of 40° C. to 80° C.

[0043] As mentioned above, the textile remains stationary, in a static state, and the depolymerization solution is pumped into the reaction chamber containing the textile, through the textile and out of the reaction chamber, preferably several times until the polyester is completely depolymerized. The garment fills a portion of the reaction (i.e. depolymerization) chamber and is held in place by suitable structural elements that prevent the textile from moving inside the reaction chamber. Preferably, the textile is kept in a compressed state to completely fill the relevant portion of the chamber: this state favors the flow of the depolymerization solution through all the static garments and a high productivity of the process.

[0044] The advantage of the present invention is that during the depolymerization step, some types of dyes are removed from the textile. In fact, reactive dyes are removed from waste textiles by hydrolysis via reduction decolorization. The removal of reactive dyes can be carried out by technical means known in the art per se.

[0045] Advantageously, by circulating the depolymerization solution through the textile, indigo and indigoid dyes can be at least partially removed (ie detached) from the textile. The detached indigo dye accumulates in the solution, from which it can be recovered in a subsequent step.

[0046] According to one possible aspect, the method further comprises: a step of bleaching the treated fabric in the reaction chamber by means of a bleaching / decolorizing solution, the bleaching / decolorizing solution comprising an oxidizing agent, such as hydrogen peroxide, perborate, percarbonate, preferably hydrogen peroxide. The bleaching step is performed after the depolymerization solution is removed from the chamber; after the solution is removed, some of the depolymerization solution is typically retained in the textile. Similar to the depolymerization solution, the bleaching solution is also circulated through the static textile, for example by a pump.

[0047] Advantageously, the bleaching solution is capable of removing the color imparted by the residual indigo dye from the treated textile. The bleaching solution may include a stabilizer and a wetting agent, preferably a dispersant, for example Permulsin FF (Bozzetto Group) and / or a wetting agent, for example Sanwet NW 2109 (CHEMKO) and / or a stabilizer for an oxidizing agent, for example Sanstabil A100 (CHEMKO).

[0048] According to a feasible aspect, the bleaching solution is provided in a certain amount according to a bath ratio of the textile (dry) to the bleaching solution of 1 / 2 to 1 / 20 by weight, preferably 1 / 7 to 1 / 9, more preferably 1 / 8. The pH of the bleaching solution is alkaline; the alkali concentration of the bleaching solution is at least 10 g / L of 48°Be NaOH solution, preferably 20 g / L to 30 g / L, more preferably 25 g / L.

[0049] According to one possible aspect, the amount of oxidant present in the bleaching solution is effective to remove the indigo color from the textile. In a preferred embodiment, the bleaching solution comprises 1 g / L to 7 g / L, preferably 4 to 7 g / L, and even more preferably 5 g / L of a 50 wt% (weight / weight) hydrogen peroxide solution. In other words, the concentration of H2O2 in the bleaching solution is in the range of 0.5 g / L to 3.5 g / L, preferably 2 g / L to 3.5 g / L, more preferably 2.5 g / L. The bleaching solution is heated to a temperature between 100°C and 110°C, preferably 105°C, and maintained at said temperature for a period of 100 minutes to 150 minutes, preferably 120 minutes. After said time, the bleaching solution is cooled to a temperature of 40°C to 80°C, preferably 50°C, and finally the bleaching solution is removed from the reaction chamber.

[0050] Advantageously, the bleaching solution is maintained at a temperature of 100°C to 110°C to minimize alteration and degradation of the cotton or cellulose fibers.

[0051] According to a possible aspect, the oxidant is gradually poured into the bleaching solution in the chamber for a period of time, for example, 2 to 7 minutes, preferably 5 minutes. Advantageously, the oxidant is gradually poured into the bleaching solution to control the presence of undesirable gas content in the chamber, which is produced by the reaction between the bleaching solution and the oxidant. Controlling the amount of gas content in the chamber prevents an undesirable increase in the pressure in the chamber and improves the efficiency of the hydrogen peroxide.

[0052] According to one possible aspect, the method further comprises a step of washing the treated fabric with a washing solution, wherein the washing solution preferably comprises a dispersant at a concentration of 1 g / L to 5 g / L; in the washing step, TPA salt and EG that may be present in the textile are removed from the textile.

[0053] Examples of dispersants are Permulsin FF (Purset Group) or Develope JFR NB (MKS DEVO).

[0054] Advantageously, the mass concentration of sodium hydroxide in the washing solution is less than 20% by weight in order to avoid tearing or breaking of the cellulose fibers.

[0055] According to a feasible aspect, the bath ratio of the washing solution is in the range of 1 / 2 to 1 / 20, preferably 1 / 7 to 1 / 9, more preferably 1 / 8. Similar to the steps of depolymerization and bleaching of the textile, the washing step is also carried out on the static textile in the reaction chamber by circulating the washing solution stream through the textile.

[0056] According to one possible aspect of the invention, after depolymerization and removal of polyester monomers, the treated fabric comprises cotton fibers having a degree of polymerization between 600 and 3500 and having detectable mechanical properties such as breaking strength and tearing strength making said fibers suitable for further use in yarn production.

[0057] The degree of polymerization can be calculated by measuring the relative viscosity with a capillary viscometer, then calculating the corresponding intrinsic viscosity according to the ISO5351 standard, and then calculating according to equations known in the art, such as the modified Mark-Houwink-Sakurada equation for cellulose-solvents described in the literature Sihtola H, Kyrklund B, Laamanen L, Palenius I (1963)-Comparison and conversion ofviscosity and DP-values ​​determined by different methods, Paperi Ja Puu, 45:225-232. In detail, the viscosity can be calculated from the equation [η] = 954 x log [η rel ]-325, which is also mentioned in WO2019 / 140245. DP is given as the range of the following equation: DP 0.905 =0.75x[n]; and DP=1.9[n].

[0058] According to a preferred embodiment of the method of the present invention, for example, see Figure 7, the depolymerization solution obtained after the depolymerization cycle is reused in a subsequent depolymerization cycle for a new batch of textiles to be treated. The same aspect applies to the bleaching solution and, possibly, to the washing solution, so that they can be reused in subsequent bleaching cycles and washing cycles, respectively. This aspect of the invention offers the advantage of a significant reduction in water consumption. The applicant has found that the depolymerization solution can be used several times, for example at least twenty times or even more, without losing its properties, provided that the NaOH content is restored to the initially required amount before being reused in a continuous treatment cycle for a new batch to be depolymerized. Moreover, it has been found that the increase in the content of TPA salts and EG occurring in each cycle does not impair the chemical properties and depolymerization capacity of the solution.

[0059] The number of times the depolymerization solution can be reused in another depolymerization cycle depends on the initial amount of polyester present in the textile to be treated. In other words, the greater the amount of polyester present in the textile to be treated, the fewer the number of cycles the depolymerization solution can be reused for a new batch of textile to be treated. This can also apply to the bleaching solution and / or the washing solution.

[0060] The depolymerization solution, bleaching solution and washing solution can be set to their required initial state (e.g., to an initial NaOH concentration) and reused 1 to 100 times, preferably 10 to 100 times, typically 10 to 40 times in further cycles of the process of the invention.

[0061] One advantage of the present invention is that after the depolymerization step, the cotton or cellulose textile, in particular the fabric, does not become a cellulose pulp as occurs in the prior art when a complete depolymerization is carried out. On the contrary, thanks to the present invention, the reduction in the DP (degree of polymerization) of the cellulose fibers is kept at a completely acceptable level and in any case renders the cotton fibers of the textile suitable for recovery as short fibers after depolymerization and after the entire process (i.e. including bleaching and washing) and for recycling and for the production of yarns and fabrics (without chemical pretreatment). In fact, the treated blended fabric, i.e. the blended fabric after depolymerization according to the present invention, retains detectable and useful mechanical properties, such as breaking strength or tear strength, as shown in Example 3 and Table 1.

[0062] The breaking strength of the fabric in the warp and weft directions obtainable after the method of the present invention can be measured according to ASTM D5034. The final result of the test provides the weight (kilograms, Kg) required to break the textile before and after the method.

[0063] The tear strength of the fabric in the warp and weft directions obtainable after the method of the present invention can be calculated according to ASTM D 1424. The final result of the test provides the weight (in grams, gr) required to tear the textile before and after the method.

[0064] According to a feasible aspect, if the textile, i.e. fabric and clothing, contains one or more optical brighteners, the method further comprises a pretreatment step of removing the optical brightener from the textile with a suitable solvent before the depolymerization step of the method. In this step, the solution removes the brightener and / or inhibitor and / or quencher; the removal of the brightener is carried out at a bath ratio of 1 / 2 to 1 / 20, preferably 1 / 10, at a temperature between 30°C and 40°C for a period of 10 minutes to 30 minutes.

[0065] Optical brighteners are chemical compounds that can be added to fabrics to provide a whiter or brighter effect in areas where the optical brightener is present than in areas of the fabric where the optical brightener is not present.

[0066] The optical brightener present in the textile blend should be removed prior to step a) above, in order to obtain in step e) a treated textile comprising cellulosic fibers having a uniform color or a uniform brightness level.

[0067] Advantageously, the pretreatment step for removing the optical brightener can be achieved with an aqueous solution comprising a decolorizing agent for the optical brightener [e.g. Fluorex DEL (CHT Group)] and preferably also a wetting agent [e.g. Sanwet M30 (CHEMKO)]. Preferably, the mass concentration of the decolorizing agent is between 0.2 g / L and 1.2 g / L.

[0068] The present invention also relates to an apparatus for recycling blended textiles comprising polyester fibers and cotton or cellulose fibers, the apparatus comprising a reaction chamber configured to contain waste textiles, a tank for containing a depolymerization solution and optionally any of a bleaching solution or a washing solution, a pump for feeding the depolymerization solution from the tank to the reaction chamber and circulating it through the reaction chamber, and control means, typically comprising heating means and cooling means, for controlling the temperature of the depolymerization solution inside the chamber.

[0069] The chamber is configured to hold the textile to be recycled. Typically, the chamber is made of a material suitable for contact with the depolymerization solution, the bleaching solution and the washing solution. Examples of such materials are steel metal, preferably stainless steel, more preferably stainless steel such as AISI 316 and AISI 316 / 316L.

[0070] A plurality of tanks containing depolymerization solution, bleaching solution and washing solution are fluidly connected to the chamber to feed or remove the solution from the chamber. Typically, the plurality of tanks are made of a material suitable for contacting with the depolymerization solution, bleaching solution and washing solution.

[0071] Advantageously, the pumps allow controlling the flow of the depolymerization solution, the bleaching solution and the washing solution from the plurality of tanks to the chambers. Typically, the pumps may be selected from centrifugal pumps, positive displacement pumps, axial flow pumps or similar pumps; the preferred pumps are centrifugal pumps. Advantageously, the device may also allow reversing the flow direction of the solutions in the chambers in a manner known per se, for example by means of alternating switching means connected to the pumps.

[0072] As mentioned previously, the depolymerization solution is circulated through the textile (and the chamber) by the pump until the polyester material in the textile has been depolymerized and completely or substantially completely removed from the textile (removed as monomers).

[0073] The chamber is equipped with a heating device to increase the temperature of the depolymerization solution. The heating device can be placed inside the chamber, for example, at the bottom of the chamber. The heating device can be a coil through which superheated steam is supplied to heat the depolymerization solution. Means for cooling the solution are also provided, for example, in the form of another coil connected to a cooling fluid source (e.g., cold water). Advantageously, the same coil can be used as a heating and cooling device by selectively connecting to a heating or cooling fluid source.

[0074] Typically, the heating and cooling means are connected to a control means which is further connected to a sensing means which detects the temperature of the depolymerization solution inside the chamber.

[0075] According to one possible aspect, the chamber comprises a filter basket to contain the textiles to be treated. Advantageously, the filter basket comprises a rigid structure, for example a metal structure, generally in the form of a cylinder, provided with openings along its walls to enable the depolymerization solution to flow inside the chamber and through the textiles. Placing the waste mixed fabric in the filter basket allows the textiles to be confined in the basket during the flow of the solution; in other words, the textiles remain stationary, i.e. static, while the depolymerization solution is forced to flow through the textiles in the chamber. Advantageously, the textiles fill the entire space of the filter basket, preferably they are compressed into the basket; above the basket, the chamber is provided with an empty space, as can be seen from the figure.

[0076] Preferably, the filter basket is a perforated rigid container shaped according to the reaction chamber, including lateral perforated walls and a perforated rigid column located at the central axis of the perforated rigid basket. Advantageously, the depolymerization solution can flow from the perforated rigid column to the waste mixed fabric and flow through the lateral perforated walls, or from the lateral perforated walls to the recycled textile and flow through the recycled textile, thereby allowing the depolymerization solution to contact the waste mixed fabric evenly and uniformly over time.

[0077] According to a possible aspect, the chamber comprises at least one, preferably a plurality of perforated separation elements, which are housed in the basket and are positioned along the central column and extend transversely to the central column. The separation element comprises a perforated plate on which the textile can be placed. The perforated plate allows the solution to flow through the holes. The separation element also serves as a holding device to keep the textile in a static state.

[0078] The present invention also relates to a textile obtained by the method of the present invention, the textile comprising cotton fibers having a degree of polymerization between 600 and 3500. In some embodiments, the cotton fibers are contained in a fabric obtained by the method of the present invention, the fabric having a measurable breaking strength or tearing strength in the warp and weft directions. Since the polyester substance in the original blended textile is no longer present, the treated yarn or treated fabric has empty spaces that originally accommodated the polyester filaments, fibers or yarns.

[0079] As previously mentioned, the method of the present invention can be used to perform the treatment process of clothing without having to cut the clothing or remove parts of the clothing. In particular, the clothing can include a fabric and a reduced amount of polyester, the fabric being composed of yarn made of cotton (i.e., 100% cotton fabric), the polyester being derived from sewing thread, which is used to sew (i.e., sew) parts of the clothing together in a manner known in the art. These clothing or parts thereof can be treated according to the methods and equipment previously disclosed for treating blended textiles. The reaction conditions in the method for treating clothing in which the fabric is composed of cotton or other cellulose fibers may be milder than the conditions used in the method for treating blended textiles (e.g., having a 40-50% polyester content), such as treating blended fabrics with fibers.

[0080] Therefore, another object of the present invention is a method for recycling garments and parts thereof comprising polyester and cellulose fibers, preferably cotton fibers, wherein the garment comprises a plurality of fabric parts sewn together by sewing yarns, the fabric parts consisting of cotton yarns or cellulose yarns, preferably 100% cotton fabric parts, and the sewing yarns are polyester sewing yarns, the method comprising depolymerizing the polyester yarns in an alkaline aqueous solution, comprising the following steps:

[0081] a) providing a certain amount of the garment in a reaction chamber;

[0082] b) providing an amount of the alkaline depolymerization solution according to a bath ratio of the garment weight to the solution weight in the range of 1 / 2 to 1 / 20, preferably 1 / 4 to 1 / 8;

[0083] c) circulating the amount of depolymerization solution through the garment to depolymerize the polyester into corresponding monomers, and removing the polyester monomers from the garment;

[0084] d) removing the depolymerization solution from the reaction chamber;

[0085] wherein, in step c), the temperature of the depolymerization solution is in the range of 101°C to 160°C, and wherein

[0086] e) the garment is in a resting (ie static) state and the solution is circulated through the garment to provide a treated garment substantially free of polyester material, which comprises cellulosic staple fibers, preferably cotton staple fibers.

[0087] In this case, according to the method of the invention, sewing yarns in the form of polyester, which sew together fabric parts forming a garment, are depolymerized so that said fabric parts are detached from each other and can be separated, possibly for recycling.

[0088] According to the present specification, clothing includes any clothing item, such as T-shirts, pants, jeans, jackets, shirts, sportswear, etc. In an embodiment, clothing may contain non-textile elements, such as zippers, rivets, buttons (these elements are usually made of metal or plastic) and labels. Advantageously, if the clothing contains non-textile elements or parts (such as buttons, rivets, zippers), according to the method of the present invention, the polyester sewing yarn that sews the parts of the clothing together is depolymerized so that the parts of the clothing are separated.

[0089] It was surprisingly found that at the end of the process, in particular after the bleaching and washing steps, non-textile elements such as metal or plastic elements detach from or are loosely attached to the garment and can be easily removed from most of the treated garments.

[0090] Thus, the method for recycling a garment made of fabric consisting of cotton or cellulose fibers may provide a further step wherein, after at least part of the method has been performed, the non-textile element is removed from the treated garment.

[0091] Advantageously, in the process, a depolymerization solution is fed to the chamber so that the polyester fibers of the sewing yarn of the waste garments maintained in a stationary state within the reaction chamber are depolymerized under reaction conditions that allow the ester bonds of the polyester to be cleaved into its monomers terephthalic acid (as disodium salt (Na2TP)) and ethylene glycol (EG) and significantly reduce the modification and depolymerization of the cellulosic staple fibers.

[0092] Advantageously, the temperature of the depolymerization solution, and thereby the pressure, is increased accordingly in the closed chamber to a value such that the polyester sewing yarn is depolymerized, but degradation or alteration (e.g., reduction in degree of polymerization) of the cellulosic fibers (e.g., cotton staple fibers) in the cellulosic fabric portion of the garment from which the garment is made is minimized and possibly avoided.

[0093] Advantageously, in step c), a selected amount of depolymerization solution is circulated at the claimed temperature, preferably by means of a pump in the chamber, and through the garments throughout the length of step c) of the process. In other words, the waste garments are maintained in a substantially static state and are contacted with the depolymerization solution several times by repeatedly passing (i.e. circulating) the depolymerization solution through the garments, so as to increase the content of disodium terephthalate (Na2TP) or terephthalate ions or EG in the solution, or more generally, the content of products from degraded polyester in the solution, while maintaining the cotton or cellulose fibers as intact as possible. It was found that the combination of keeping the garments in a static or static state and circulating (i.e. flowing) the depolymerization solution through the garments allows complete depolymerization of the polyester to be achieved, while greatly reducing or possibly avoiding the depolymerization of the cellulose (preferably cotton) fabric portion forming the garment.

[0094] According to one aspect, the depolymerization solution is an alkaline solution, preferably an alkaline solution comprising sodium hydroxide or potassium hydroxide. The solution preferably contains 70 g / L to 500 g / L, more preferably 76 to 120 g / L of a sodium hydroxide solution having a Baumé degree equal to 48° Be. In other words, the NaOH concentration in the depolymerization solution is in the range of 33 g / L to 237 g / L of NaOH, preferably 36 g / L to 57 g / L of NaOH.

[0095] According to a feasible aspect, the amount of depolymerization solution to be used in the method is selected according to the amount of clothing to be treated. In some embodiments, the bath ratio is in the range of 1 / 2 to 1 / 20, preferably 1 / 2 to 1 / 15, and most preferably 1 / 5 to 1 / 8; the bath ratio is the weight ratio between the weight of the clothing and the weight of the depolymerization solution.

[0096] According to a feasible aspect, in step c), the temperature of the depolymerization solution is in the range between 101° C. and 160° C., preferably in the range of 120° C. to 160° C. Advantageously, the temperature of the depolymerization solution is in the range between 130° C. and 140° C.; the claimed range minimizes changes in the chemical and mechanical properties of the cotton or cellulose fibers, such as the length and size of the fibers, the degree of polymerization of the cellulose.

[0097] According to one feasible aspect, during step c), the pressure in the chamber is in the range of 1.05 bar (15.23 bar) to 7.0 bar (101.5 bar), preferably 1.4 bar (39.16 bar) to 3.5 bar (101.5 bar), more preferably 2.7 bar (39.16 bar) to 5.5 bar (79.77 bar).

[0098] According to one possible aspect, the depolymerization in step c) is carried out for a period of 60 to 240 minutes or 91 to 240 minutes, preferably 60 to 150 minutes, more preferably 60 to 120 minutes.

[0099] All details of the method and apparatus of the present invention discussed previously with reference to the treatment of blended fabrics are also applicable to the treatment of garments and are used to carry out the method disclosed above for treating garments or parts thereof consisting of cotton or cellulose fibers, fabrics and polyester sewing yarns. In particular, the depolymerization solution is circulated through the garment under the disclosed reaction conditions until the polyester sewing yarn is completely depolymerized; preferably, depending on the content of the textile material, the bleaching / decolorization and washing steps may be carried out under the conditions previously disclosed for treating textiles. Example 6 discloses the results of treating a garment comprising a non-woven portion and a fabric of 100% cotton (referred to as 100% cotton fabric).

[0100] In a preferred embodiment, process step c) is carried out at 130° C. for 120 minutes, preferably at a pressure of 2.7 bar (39.16 psi) to 5.5 bar (79.77 psi).

[0101] Advantageously, the flow (i.e. circulation) of the depolymerization solution at the claimed bath temperature and pressure and at the bath ratio causes complete or substantially complete depolymerization of the polyester sewing yarn. Advantageously, the cotton fibers obtained by the process of the invention are in the form of staple fibers and the degree of polymerization is high enough to allow the fibers themselves to be recovered (by mechanical means) and used for the production of yarns and fabrics without any chemical treatment.

[0102] In the following description, the invention will be disclosed by reference to fabrics and garments, in particular cotton blended fabrics and garments; it should be noted that the same steps and descriptions generally apply to textiles as described above, i.e., also to yarns and fibers and other cellulosic fibers besides cotton. BRIEF DESCRIPTION OF THE DRAWINGS

[0103] Other aspects and advantages of the invention will be discussed in more detail with reference to the enclosed drawings, given by way of non-limiting examples, in which:

[0104] Figure 1 is a schematic diagram of an apparatus for containing waste fabrics, the fabrics comprising polyester fibers and cellulose fibers;

[0105] Figure 2 Shows Figure 1 A schematic diagram of an apparatus and a treated fabric comprising cellulose fibers at the end of the method;

[0106] Figure 3a Shows Figure 1 A perspective view of a portion of a filter basket;

[0107] Figure 3b Shows Figure 1 A cross-sectional view of a filter basket and a closed reaction chamber;

[0108] Figure 4 Shows Figure 1 A perspective view of a perforated separation element;

[0109] Figure 5a An example of a fabric prior to the method is shown, wherein the fabric comprises polyester fibers and cellulose fibers;

[0110] Figure 5b The method shown in FIG. Figure 5a A fabric comprising cellulose fibers but no polyester fibers;

[0111] Figure 6a An example of a garment prior to the method is shown, wherein the garment prior to the method comprises polyester fibers and cellulose fibers and a non-woven portion;

[0112] Figure 6b The method shown in FIG. Figure 6a of clothing, wherein the clothing comprises only cellulosic fibers;

[0113] Figure 7 A schematic diagram of a process comprising a depolymerization step, a bleaching step and a washing step and possible reuse of the associated solutions is shown;

[0114] Figure 8 Shows Figure 1 A perspective view of the heating and cooling elements of the device;

[0115] Fig. 9 two photographs (a and b) showing a garment before (a) and after (b) the method of the invention; and

[0116] Fig.10 yes Fig. 9 Black and white version of the photo.

[0117] Specific implementation methods of the present invention

[0118] Figure 1 and Figure 2 An apparatus 100 is shown which can be adapted to carry out the method of the invention on waste mixed fabrics 1 and waste garments comprising polyester and cellulose fibres, preferably cotton fibres, wherein the garments comprise a plurality of fabric portions which are sewn together by means of sewing yarns, the fabric portions being 100% cellulose fabric portions, preferably 100% cotton fabric portions, and the sewing yarns being polyester sewing yarns. For the sake of simplicity, in the following description only reference will be made to mixed fabrics. Figure 1In FIG. 1 , the apparatus is shown at an initial stage of the method: it comprises a chamber 10 filled with a fabric blend to be treated, said fabric comprising polyester fibres 4 and cotton fibres 40 .

[0119] Alternatively, the chamber 10 may be filled with waste clothing comprising polyester and cellulose fibers, preferably cotton fibers, wherein the clothing comprises a plurality of fabric portions sewn together by sewing yarn, the fabric portions being 100% cellulose fabric portions, preferably 100% cotton fabric portions, and the sewing yarn being polyester sewing yarn.

[0120] Typically, the chamber is cylindrical in shape and comprises side walls, a bottom wall and a lid 91. The closed chamber is configured to withstand the pressures generated in the method of the present invention.

[0121] In the embodiment shown, the chamber 10 contains a filter basket 6 for receiving waste mixed fabrics. Figure 3a and 3b As shown, the filter basket 6 is in the form of a cylindrical container, usually made of metal, which includes perforated lateral walls 64 that allow the depolymerization solution 3 to flow within and through the chamber 10 in which the waste mixed fabric 1 is contained. Figure 3b As shown by arrows F1 and F2, the flow of the depolymerization solution 3 may be substantially along a first direction F2 from the central axis A through the perforated inner wall or column 65 toward the outer wall 64, or flow from the perforated wall 64 along a second direction F1 substantially opposite to the first flow direction.

[0122] In other words, the solution in the chamber 10 can circulate in a first direction or in a second direction. In the first direction, the flow in the chamber 10 flows from the perforated inner wall 65 of the filter basket 6 and is forced through the fabric 1 to leave the filter basket 6 from the perforated wall 64. In the second direction, the feeding direction is reversed, i.e., the solution is fed into the chamber corresponding to the perforated outer wall 64 and is forced through the fabric towards the inner perforated portion 65 and the central axis A.

[0123] If the circulation (i.e. flow) is alternating, in one embodiment, the first recirculation is preferably carried out in the first direction for 2 to 6 minutes, preferably 4 minutes. The second recirculation is carried out in the second direction for 4 to 8 minutes, preferably 6 minutes. The flow in the process can be carried out entirely in the first direction, or the flow can be carried out only in the second direction during the entire process.

[0124] Advantageously, the depolymerization solution 3 flows in a first radial direction and / or in a second radial direction through the fabric, out of the chamber and back into the chamber, which allows the depolymerization solution 3 to reach all the waste fabric 1 that remains stationary (i.e. not agitated in the solution) and ensures uniform depolymerization of the polyester in a short time. Maximizing the flow injection from the perforated walls of the filter baskets 64 and 65 provides for proper absorption of the depolymerization solution 3 in the waste fabric 1 and, therefore, maximizes the depolymerization of the polyester fibers 4.

[0125] In the illustrated embodiment, see Figure 3b and Figure 4 The chamber 10 comprises at least one, preferably a plurality of, perforated separation elements 60, which are transverse to the central column 65 and are housed in the basket 6. The diameter of the separation element 60 is smaller than the diameter of the basket 6, i.e., smaller than the distance between the inner surfaces 641 of the lateral walls 64, to allow the element 60 to be inserted into the basket without leaving too wide a gap on the sides. Figure 4 As can be seen in the figure, the element 60 is provided with a central hole 62 which allows the separation element to slide along the column 65 and the internal basket 6 without mechanical interference. The separation element 60 allows the basket 6 in the chamber 10 to be filled to the maximum extent with waste mixed fabrics and prevents the fabrics and textiles from moving in the basket. In the case where more than one separation element 60 is housed in the filter basket 6, a pile of waste mixed fabrics 1 will be housed on top of each separation element 60. Advantageously, the element 60 comprises a perforated plate 601 to ensure the flow of the depolymerization solution 3 inside the chamber 10. Figure 3b A top retaining element 603 is also shown.

[0126] The apparatus 100 also comprises a plurality of tanks or reservoirs to contain the depolymerization solution 3 in tank 7, the bleaching solution 30 in tank 7a and the washing solution in tank 7b. The tanks are connected to the chamber 10 by respective pipes and a circulation loop comprising a pump 8 connected to the chamber 10 by conduits 72 and 74 and fluid alternation means 82.

[0127] The depolymerization solution 3 can flow from the tank 7 to the chamber 10 through the conduit 71 and the conduits 72 and 74 according to the flow direction provided by the flow alternating device 82. Figure 1 and 2 As can be seen in the figure, the duct 72 is connected to the inner column 65 of the basket 6 so that it can feed the solution to the inner column 65 of the basket 6; the duct 74 is connected to the outside of the chamber corresponding to the wall 6 of the basket to receive the circulated solution in the logistics duct 74 opposite to the solution fed to the chamber, that is, the solution that has flowed through the textiles and the chamber.

[0128] The alternating device 82 provides an advantageous alternating circulation of the depolymerization solution within the chamber 10. After the depolymerization solution is fed to the chamber 10, the valves V2 and V1 are positioned so that the depolymerization solution can circulate through the conduits 72, 74, wherein the depolymerization solution recirculates in a counterclockwise direction. Alternatively, the flow direction can be reversed by means of the alternating device 82, so that the recirculation of the depolymerization solution through the conduits 72, 74 and the chamber 10 is in a clockwise direction.

[0129] Bleaching solution 30 and washing solution 80 may flow from a plurality of tanks 7a and 7b to conduits 72 and 74, respectively. Valves V1, V2 and V3 are located on the loop pipes to control the flow in the conduits. The apparatus 100 also includes a plurality of backup chemical tanks 20 to provide reagents to tank 7 through conduits 21, 22, or to tank 7a through conduits 21, 23, or to tank 7b through conduits 21, 24. The reagents may be alkaline solutions or bases, oxidants, wetting agents, dispersants, stabilizers, decolorizing agents and the like.

[0130] The apparatus 100 further comprises heating and cooling elements 9a, 9b and a temperature sensor 90 to control the temperature of the depolymerization solution 3 or the bleaching solution in the reaction chamber 10. Figure 8 The coils shown implement the heating and cooling means, and can be selectively connected to a steam source 9a or a cold water source 9b to heat or cool the solution in the chamber 10, respectively.

[0131] The present invention provides a method for recycling a waste mixed fabric 1 containing polyester 4 and cellulose staple fibers (preferably cotton staple fibers 40), the method comprising depolymerization of polyester in an alkaline aqueous solution, comprising the following steps: a) providing a certain amount of the fabric in a reaction chamber 10; b) providing a certain amount of the alkaline depolymerization solution 3 according to a bath ratio of the fabric weight to the solution weight in the range of 1 / 2 to 1 / 20; c) circulating the amount of depolymerization solution 3 through the fabric 1 at least once, preferably several times, to depolymerize the polyester fibers 4 and remove the polyester fibers 4 from the fabric; d) removing the depolymerization solution 3 from the reaction chamber 10, wherein the temperature of the depolymerization solution is in the range of 101°C to 160°C, and wherein e) circulating the solution to provide a treated textile 5 substantially free of polyester material, the treated textile 5 comprising yarn containing cellulose staple fibers, preferably cotton staple fibers 40.

[0132] In the preferred embodiment shown, waste fabric 1 is placed in a basket 6, possibly using one or more separating elements 60. Preferably, the basket is completely filled with fabric to be treated.

[0133] Prior to the method of the present invention, Figure 5a The waste mixed fabric 1 and Figure 6aThe garment 1a made of a blended fabric comprises polyester fibers 4 and cotton fibers 40. The garment 1a comprises non-woven fabrics, i.e. non-textile parts, such as buttons 2 or rivets and zippers made of metal or plastic materials. After the method of the present invention, Figure 5b and Figure 6b , the same fabric and garment are shown in , where the polyester fibers and filaments have been depolymerized into monomers and are no longer present in the fabric 5 and garment 5a, while the cotton yarn 40 and the cotton portion of the blended yarn (e.g., the sheath of the core-spun yarn) are still present in the form of the fabric and garment. The treated garment 5a does not include the buttons 2 (nor does it include rivets and zippers) because it has been additionally treated in a destoning machine or other machine suitable for removing loose solids originating from the treated garment, as discussed below. Figure 6b A garment without buttons and without polyester warp yarn is schematically shown; it should be understood that, as explained, the depolymerization of the sewing yarn made of polyester causes the treated garment to be separated into multiple detached pieces, such as Fig. 9 shown. Fig. 9 Two photographs of a garment are shown, namely a photograph of the original garment before treatment (photo a, left) and a photograph of the original garment after depolymerization and bleaching (and final washing) treatment (photo b, right).

[0134] After filling the basket 6 with the textile, a depolymerization solution 3 containing sodium hydroxide or potassium hydroxide, preferably sodium hydroxide, is fed to the chamber. This solution is prepared by adding 70 g / L to 500 g / L of a NaOH solution in water, the NaOH solution having a Baume degree of 43 to 50 ° Be, preferably 48 ° Be. In a preferred embodiment, the amount of the 48 ° Be NaOH solution added to the water is in the range of 76 g / L to 120 g / L.

[0135] The amount of depolymerization solution 3 is selected to have a bath ratio between 1 / 2 and 1 / 20, more preferably 1 / 4 to 1 / 6 of textile weight to bath weight. The depolymerization solution is heated by coils 9 to which steam, ie superheated steam, is supplied.

[0136] The temperature of the depolymerization solution 3 in the chamber 10 is controlled to depolymerize the polyester fibers 4 while maintaining the original mechanical and chemical properties, polymerization degree and size of the cotton fibers 40 in the fabric 1 as much as possible. The temperature of the depolymerization solution 3 in the chamber 10 is controlled by a sensor 90 and maintained in the range of 101° C. to 160° C., preferably 130 to 140° C.

[0137] According to a possible aspect, in step c), the pressure in the chamber 10 is in the range of 1.05 bar (15.23 bar) to 7.0 bar (101.5 bar), preferably 2.7 bar (39.16 psi) to 7.0 bar (101.5 psi), more preferably between 2.7 bar (39.16 psi) and 5.5 bar (79.77 psi). The pressure in the closed chamber 10 may vary due to changes in the temperature of the depolymerization solution 3 or the bleaching and washing solution.

[0138] According to a preferred aspect, the temperature of the depolymerization solution 3 in the chamber 3 is maintained for a period of 91 to 240 minutes, preferably 100 to 150 minutes, more preferably 120 minutes. After said period, the depolymerization solution is cooled to a temperature of 40 to 80°C.

[0139] The depolymerization solution 3 is then removed from the chamber 10 via conduits 71, 72, 74 and control valves V1, V2.

[0140] If the treated fabric 5 is a garment equipped with metal or plastic elements such as zippers, rivets, buttons at the beginning of the process, the zippers and other metal or plastic elements can be easily separated from the treated garment after the process, due to the lack of polyester fibers and yarns resulting in a weaker final adhesion to the fabric, especially after the bleaching step. In fact, all garment seams made of polyester yarn are depolymerized and thus removed from the garment, so that metal or plastic elements can be removed from the treated fabric (i.e. the treated garment).

[0141] The reactive dye is hydrolyzed by the depolymerization solution 3 to provide a non-dyed fabric substantially free of polyester. During the depolymerization step, a portion of the indigo is also removed from the fabric.

[0142] After depolymerization and removal of the depolymerization solution 3 from the chamber 10, if the fabric comprises indigo-dyed fibers, the treated fabric 5 undergoes a bleaching step with a bleaching solution 30 in the chamber 10. The bleaching solution 30 is supplied to the chamber 10 via a conduit 73 connected to a pump 8 and conduits 72, 74, 73.

[0143] The bleaching solution 30 is provided in an amount such that the bath ratio is in the range of 1 / 2 to 1 / 20, preferably 1 / 7 to 1 / 9, more preferably 1 / 8; the bleaching solution contains an alkali, preferably NaOH, in a concentration of at least 10 g / L, preferably 20 g / L to 30 g / L, more preferably 25 g / L of a NaOH solution having a Baume degree equal to 48° Be. In other words, the concentration of NaOH in the bleaching solution is at least 4.73 g / L, preferably 9.47 g / L to 14.20 g / L of NaOH, more preferably 11.83 g / L of NaOH.

[0144] The concentration of hydrogen peroxide in the bleaching solution is in the range of 2 to 7 g / L, preferably 5 g / L, and the solution is heated to 100 to 110° C., preferably 105° C., by means of coil 9 and kept at said temperature for 60 to 150 minutes, preferably 100 to 150 minutes, preferably 120 minutes. After said time, the depolymerization solution is cooled to a temperature of 40 to 80° C. and discharged back to tank 7a.

[0145] According to one possible aspect, the oxidizing agent is gradually added to the bleaching solution 30 in the chamber 10 for a period of 2 minutes to 7 minutes, preferably about 5 minutes.

[0146] In order to avoid an undesirable increase in pressure in the closed chamber 10 and to maintain a good efficiency of the oxidizing agent, the oxidizing agent is preferably added to the bleaching solution 30 gradually.

[0147] The method further comprises the step of washing the treated fabric 5 after depolymerization or bleaching with a washing solution 80 containing a dispersant. The washing solution 80 is held in a tank 7b and supplied to the chamber 10 through a conduit 74 via a conduit 75 connected to a pump 8. The liquor ratio of the washing solution 80 is in the range of 1 / 2 to 1 / 20, preferably 1 / 7 to 1 / 9, more preferably 1 / 8.

[0148] The step of washing the treated textile 5 comprising cellulose fibers 40 may be performed after the above step e), or may be performed after the treated textile 5 has been subjected to the bleaching solution 30. In other words, the washing step may be performed after the depolymerization of the polyester fibers is completed (when no bleaching is performed) or after the treated textile 5 has been subjected to a bleaching step (in which the dye has been removed).

[0149] Advantageously, after step e), the treated fabric 5 comprises cotton fibers having a degree of polymerization of up to 3500. The product of the process of the invention does not contain cellulose pulp. In other words, the cotton yarn-containing fabric obtained by the process of the invention is still in the form of a fabric, but its initial polyester component has been removed.

[0150] Figure 5b A treated fabric 5 is shown which contains cotton fibres 40 but from which the polyester fibres 4 have been removed. Figure 6b A schematic diagram of a treated fabric 5 in the form of a garment 5a comprising cotton fibres 40 is shown, from which the polyester fibres 4 and non-fabric parts (zippers etc.) have been removed. Fig. 9 Photos of garments before (photo a) and after (photo b) complete treatment including bleaching are shown. After an additional drying step, the garment or fabric (or yarn or fiber) is suitable for recycling to cotton fiber in a manner known in the art, for example by using waste cotton open thread for re-spinning machines. The recycled cotton fiber can be used to prepare recycled cotton yarn suitable for weaving.

[0151] The textiles can be dried in a manner known per se, for example in a tumble dryer, or can be dried in a continuous dryer, for example a belt conveyor dryer.

[0152] As mentioned above, before the depolymerization step, the waste fabric 1 containing the optical brightener is subjected to a pretreatment step, i.e., the optical brightener is removed from the waste mixed fabric 1 with a solvent. The removal comprises a bath ratio of 1 / 2 to 1 / 20, preferably 1 / 10, at a temperature of 30° C. to 40° C. for a period of 10 to 30 minutes. Advantageously, the removal of the optical brightener prevents the appearance of fiber spots with different optical properties in the treated fabric 5.

[0153] According to a preferred embodiment of the method of the present invention, Figure 7 As shown, the depolymerization solution obtained after the depolymerization cycle is reused in the subsequent depolymerization cycle for a new batch of textiles. Similarly, the bleaching solution and the washing solution can be stored in tanks 7a and 7b for reuse in further processes, with the advantage that water consumption is greatly reduced.

[0154] The present invention will now be further disclosed with reference to the following examples, which are provided for illustrative and non-limiting purposes only.

[0155] Example 1

[0156] Before applying the method, the weight of the waste fabric is equal to 10 grams. The waste fabric contains cotton fibers in the warp direction and cotton fibers, rayon fibers, polyester fibers and spandex fibers in the weft direction. In addition, the waste fabric is dyed with indigo dye.

[0157] The recycled waste mixed fabric was treated in a closed reactor with a depolymerization solution containing sodium hydroxide (48° Be) at a concentration of 90 g / L. The depolymerization solution was heated to reach a temperature of 130° C. and maintained at said temperature for 120 minutes. The bath ratio was equal to 1 / 6. The depolymerization solution was circulated through the fabric.

[0158] After 120 minutes, the depolymerization solution was cooled to a temperature of 40°C.

[0159] After treating the waste fabric with the depolymerization solution, the polyester fibers are depolymerized into monomers and separated from the treated fabric.

[0160] The treated fabric is then treated with a bleaching solution comprising 25 g / L sodium hydroxide (48 Be°), 5 g / L hydrogen peroxide, 3.0 g / L stabilizer, 1 g / L dispersant and 0.5 g / L wetting agent.

[0161] After the treated waste fabric was immersed in the bleaching solution for 5 minutes, hydrogen peroxide was gradually poured into the bleaching solution. The bath ratio of the bleaching solution was 1 / 8. The bleaching solution was then heated to 105°C for 120 minutes, and the indigo dye was removed from the treated fabric.

[0162] In the final step, the treated fabric is treated with a washing solution. The washing solution contains a dispersant (eg, Develope JFR NB-MKSDEVO) at a concentration of 3 g / L. The bath ratio is equal to 1 / 8.

[0163] The treated woven fabric was washed by heating the wash solution to 95°C for 30 minutes. The washed treated fabric was further subjected to a recovery process known in the art.

[0164] Example 2

[0165] 500 Kg of mixed waste fabrics of different types were placed in the reaction chamber. The fabric yarns included polyester filaments and cotton fibers and included indigo dyed warp and / or weft yarns.

[0166] The waste fabric was treated with 3000 L of the depolymerization solution to obtain a bath ratio of 1 / 6. The depolymerization solution contained 90 g / L of 48° Be sodium hydroxide solution, ie, the NaOH concentration was about 43 g / L.

[0167] The depolymerization solution was heated to a temperature reaching 130° C. and maintained at said temperature for a period of 120 minutes, during which the depolymerization solution was circulated through the fabric by a pump. After 120 minutes, the depolymerization solution was cooled to a temperature of 50° C. During the depolymerization step, part of the indigo dye was removed from the fabric fibers, i.e. detached.

[0168] The depolymerized fabric was then treated with 4000 L of a bleaching solution at a bath ratio of 1 / 8. The bleaching solution contained 25 g / L of sodium hydroxide (48 Be°), 5 g / L of hydrogen peroxide, 3.0 g / L of a stabilizer, 1 g / L of a dispersant, and 0.5 g / L of a wetting agent.

[0169] After the treated fabric was immersed in the bleaching solution for 5 minutes, hydrogen peroxide was gradually poured into the bleaching solution. The bleaching solution was thus heated to 105°C for 120 minutes, and after the depolymerization was removed from the treated fabric, the indigo dye remained on the fabric.

[0170] In the final step, the treated fabric is treated with 4000 L of a wash solution resulting in a bath ratio of 1 / 8. The wash solution contains a dispersant (e.g. Permulsin FF) at a concentration of 3 g / L. The treated textile is washed by heating the wash solution to a temperature of 95°C for 30 minutes.

[0171] The washed and dried treated textiles are further subjected to recycling processes known in the art.

[0172] Example 3

[0173] A woven fabric containing mixed warp and weft yarns was used, the composition of which was 13% recycled polyester, 13% recycled cotton, 74% cotton. The yarns in the fabric were indigo dyed with an indigo concentration of 1.11 wt% and provided with a sizing of 7 wt%.

[0174] 5 kg of fabric were treated with 33 liters of a depolymerization solution containing 90 g / L sodium hydroxide solution (48° Be). The solution heated at 130° C. was circulated through the stationary fabric in a closed reaction chamber for 120 minutes.

[0175] After the first cycle of treating the waste fabric with the depolymerization solution, the mass concentration of sodium hydroxide in the depolymerization solution was equal to 55.84 g / L (48°Be), the depolymerized polyester - measured according to the amount of terephthalic acid (TPA) - was 12.52 g / L, and the concentration of indigo dye was 0.244 g / L. The treated fabric was then bleached and washed according to the conditions in Example 1.

[0176] After the bleaching step, the depolymerized polyester in the bleaching solution was 4 g / L, and after the washing step, the depolymerized polyester in the washing solution was 1.35 g / L. Thus, the total amount of depolymerized polyester after the depolymerization step, the bleaching step and the washing step was equal to 17.87 g / L. Considering that the amount of each solution in the reaction chamber was equal to 33 L, the total amount of polyester removed from the waste fabric was equal to 589.71 g.

[0177] After the whole process (one batch cycle), the depolymerized, bleached and washed fabric was dried to measure its breaking and tearing strength. The degree of polymerization (DP) of the cotton fiber was calculated. As shown in Table 1, the warp breaking strength was 53.97 Kg, the weft breaking strength was 44.97 Kg, and the degree of polymerization of the cotton fiber of the treated fabric was between 908 and 1636.

[0178] The depolymerization solution obtained at the end of the first cycle was restored to the desired NaOH content and used for a second depolymerization cycle on a new second batch of the same type of blend as used for the first cycle.

[0179] The same process was carried out for four batches of the same type of blended fabrics for a total of four times, wherein for each cycle, the mass concentration of sodium hydroxide in the depolymerization solution was restored to 90 g / L.

[0180] After the fourth process, the mass concentration of depolymerized polyester in the depolymerization solution was 37.96 g / L, which was calculated based on the amount of terephthalic acid (TPA). The mass concentration of indigo dye in the solution was 0.974 g / L. In other words, after four cycles, that is, after treating 4 consecutive batches of 5 kg of fabric with the same solution (the same solution after restoring the NaOH content), the total amount of polyester removed from the 4 batches of 5 kg was equal to a cumulative amount of 2320.23 g.

[0181] The results are reported in Tables 1, 2 and 3 below.

[0182]

[0183] Table 1

[0184] Depolymerization cycle Indigo concentration after depolymerization (g / L) Cycle 1 - Batch 1 0.244 Cycle 2 - Batch 2 0.584 Cycle 3 - Batch 3 0.742 Cycle 4 - Batch 4 0.974

[0185] Table 2

[0186]

[0187] Table 3

[0188] As shown in Table 1, the depolymerized and bleached fabrics maintained detectable mechanical properties; the fiber's warp breaking strength was up to 53.97 Kg and the weft breaking strength was 44.97 Kg. The degree of polymerization of the treated fabrics was up to more than half of the original DP, even after bleaching and washing.

[0189] Table 2 shows the increase in the amount of indigo dye in the depolymerization solution used in all batches from cycle 1 (batch 1) to cycle 4 (batch 4); indigo can eventually be recovered from the solution. Thus, the process of the present invention provides a method for recovering indigo dye from waste textiles.

[0190] Table 3 shows the increase in the amount of depolymerized polyester (g / L) in the same 33 L circulating solution used for 4 cycles. In each cycle, a depolymerization step, a bleaching step, and a washing step were applied to a new batch of fabrics. The amount of depolymerized polyester in each step is provided, as well as the total amount of depolymerized polyester after depolymerization, bleaching, and washing. For each cycle, the total cumulative amount of polyester removed from each batch of fabrics is provided in grams.

[0191] Therefore, fabrics and textiles treated according to the process of the invention, ie textiles and textiles from which the polyester fraction has been removed by depolymerization, are surprisingly suitable as secondary raw materials for the production of yarns and fabrics.

[0192] Example 4 - Comparison of DP reduction using prior art conditions and conditions of the present invention.

[0193] The fabric used in Example 3 was cut into pieces of 30x30 cm and treated according to the teaching of Example 8 of WO 2019 / 140245, i.e., with the parameters mentioned therein: 150°C, 1 h, 5% (weight / volume) NaOH, with and without MeOH (WO tests 1 to 3), and then treated according to the method of the present invention (Isko tests 2 and 3). The results are summarized in Table 4. The viscosity and DP of the cellulose in the original untreated fabric and the treated fabric are reported, and the DP reduction of the treated samples is calculated.

[0194]

[0195] Table 4

[0196] In the above examples, cut fabrics were used instead of the whole garments of Example 6. In WO tests 1 to 3, the depolymerization parameters (150°C, 1 hour, 5% (weight / volume) NaOH, cut fabrics) were set according to the prior art method disclosed in Example 8 of WO'245. In Isko tests 2 and 3, the temperature was maintained at 130°C and the solution was circulated through the stationary fabric pieces according to the method of the present invention. In WO tests 1 and 2, a reactor equipped with a drum for stirring the fabric pieces was used. The fabric remained stationary in test 1 and was stirred by the rotation of the drum in test 2. WO test 3 was carried out in stationary mode (without stirring). In WO test 3 and Isko test 3, methanol (10% weight / weight) was used as a co-solvent. In addition, WO2019 / 140245 does not mention the DP (degree of polymerization) of the cotton fibers before treatment. In contrast to the examples of WO 2019 / 140245, Table 4 also provides the DP values ​​of the original cotton fibers and their DP values ​​after the depolymerization process.

[0197] According to observations in WO test 1 in static mode (i.e. without stirring), only 1.8% of the polyester was depolymerized after applying the method for 1 hour (WO 1, 1h). When the process was carried out in static mode for up to 4 hours (WO 1, 4h), the amount of polyester on the fabric was measured to be 1.40% and 89% depolymerized. Although complete depolymerization of the polyester part could not be achieved in the static mode of the 4-hour test, a huge drop in the DP of the cellulose part was observed, with a DP drop of 43.2%. It can be clearly seen that when applying the prior art parameters in static mode, a reaction time of more than 4 hours is required to completely depolymerize the polyester in the mixed fabric. The longer time required for complete depolymerization of the polyester also leads to a larger drop in DP, which exceeds 43.2% (result after 4 hours of treatment).

[0198] In view of the results of WO Test 1, another test was conducted as WO Test 2 by adding a stirring mode of the fabric to the conditions of WO Test 1. The results show that under stirring, the polyester achieved complete depolymerization, while the fiber DP in the cut fabric dropped significantly and there was a loss of fibers separated from the fabric. The DP of the separated fibers is shown as "fiber remaining" in Table 4 and is very low.

[0199] As can be seen from Table 4, after WO Test 3 in the presence of methanol according to Example 8 of WO'245, only 6.6% of the initial amount of polyester was depolymerized, even though no significant reduction in the DP drop % of the residual cellulose was observed. Furthermore, the polyester present as the core in the cotton / polyester core-spun yarn in the blend was not completely depolymerized.

[0200] In summary, when the process was carried out according to prior art conditions, complete depolymerization of the polyester resulted in a high DP reduction in the treated cotton fibers. In contrast, Isko Test 2 carried out according to the present invention produced a significantly smaller DP reduction, shown as 28.3% in Table 4. Isko Test 3 was carried out in the presence of 10% MeOH and was found to result in a higher DP reduction than in the absence of MeOH.

[0201] In conclusion, the process of the present invention leads to complete depolymerization of polyester and the cotton fibers obtained after depolymerization have a higher DP value (lower DP drop).

[0202] Example 5 - Depolymerization of Indigo-dyed Fibers

[0203] Indigo-dyed cotton / polyester fibers having a polyester content of about 4% by weight were treated according to the present invention. In more detail, 5 kg of fibers were treated with 33 liters of a depolymerization solution containing 90 g / L of a sodium hydroxide solution having 48°Be. The solution heated at 130°C was circulated through the fibers in a closed reaction chamber for 120 minutes. The fibers were left at rest. After the fibers were treated with the depolymerization solution according to Example 3, the mass concentration of sodium hydroxide in the depolymerization solution was equal to 52.08 g / L (48°Be), the depolymerized polyester in the depolymerization solution - measured according to the amount of terephthalic acid (TPA) - was 5.38 g / L, and the concentration of indigo dye was 1.63 g / L. The degree of polymerization of the cotton fibers was calculated. The results are shown in Table 5.

[0204]

[0205] Table 5

[0206] As can be observed from Table 5, the DP loss in the cotton fiber after depolymerization of the polyester was 24%.

[0207] Example 6

[0208] A garment (pants) made of 100% cotton fabric and containing polyester in the form of sewing yarn (i.e., the only polyester in the garment was in the form of polyester sewing yarn) was used. Specifically, the 100% cotton garment was 75% virgin cotton and 25% recycled cotton. The garment was dyed with indigo, and the concentration of indigo in the garment was 1.12% by weight.

[0209] Garments also include non-textile elements, i.e. zippers, rivets, buttons.

[0210] 5 kg of garments were treated with 33 liters of a depolymerization solution containing 90 g / L sodium hydroxide solution (48° Be). The solution heated at 130° C. was circulated through the fabric in a closed reaction chamber for 120 minutes.

[0211] The degree of polymerization of the cotton fibers was calculated. The results are shown in Table 6.

[0212]

[0213] Table 6

[0214] As can be observed from Table 6, after depolymerization of polyester, the DP loss in cotton fiber of 100% cotton garment was 31%. Fig. 9 As can be seen in FIG. 1 , the non-woven element becomes detached from the garment and is removed therefrom.

Claims

1. A method for recycling waste blended textiles (1) comprising polyester (4) and cellulose fibers, preferably cotton staple fibers (40), the method comprising depolymerizing the polyester in an alkaline aqueous solution, characterized in that The following steps are involved: a) providing an amount of said textile in a reaction chamber (10); b) providing an amount of alkaline depolymerization solution (3) according to a bath ratio of 1 / 2 to 1 / 20 of the weight of the textile relative to the weight of the solution; c) circulating the amount of depolymerization solution (3) through the textile (1) to depolymerize the polyester (4) into corresponding monomers and to remove the polyester monomers from the textile; d) removing the depolymerization solution (3) from the reaction chamber (10); Wherein, in step c), the temperature of the depolymerization solution is in the range of 101° C. to 160° C., And among them e) circulating the solution through the textile to provide a treated textile (5) substantially free of polyester material comprising cellulosic staple fibers, preferably cotton staple fibers (40).

2. The method according to claim 1, wherein: The depolymerization solution is an alkaline solution, preferably, the solution contains 70 g / L to 500 g / L of a NaOH solution with a Baume degree (°Be) of 43 to 50°Be, more preferably, the solution contains 76 g / L to 120 g / L of a NaOH solution with a Baume degree (°Be) of 48°Be.

3. A method according to any preceding claim, wherein: The bath ratio of the depolymerization solution is in the range of 1 / 2 to 1 / 20, preferably 1 / 5 to 1 / 8.

4. A method according to any preceding claim, wherein: The temperature of the depolymerization solution in step c) is in the range of 120 to 160°C, preferably 130 to 140°C.

5. A method according to any preceding claim, wherein: The pressure in the chamber (10) in step c) is in the range of 1.05 bar to 7.0 bar, preferably 2.7 bar to 7.0 bar, more preferably between 2.7 bar and 5.5 bar.

6. A method according to any preceding claim, wherein: Step c) is performed for a period of 60 to 240 minutes, preferably 91 to 240 minutes, more preferably 100 to 150 minutes, most preferably 120 minutes.

7. A method according to any preceding claim, wherein: The depolymerization solution (3) hydrolyzes the reactive dyes present in the reactively dyed textile (1) and / or removes a portion of the indigo dye from the indigo-dyed textile.

8. The method according to any of the preceding claims, further comprising a step of bleaching the wet treated textile (5) obtained after step e) in the chamber (10) by circulating a bleaching solution (30) comprising NaOH and an oxidizing agent, preferably hydrogen peroxide, through the treated textile in the chamber (10), preferably the bath ratio of the bleaching solution (30) being in the range of 1 / 2 to 1 / 20, more preferably 1 / 7 to 1 / 9, most preferably 1 / 8, based on the weight of the waste textile relative to the weight of the bleaching solution.

9. A method according to any preceding claim, wherein: The textiles fill the chamber such that they are not displaced within the chamber under the effect of the flow of the solution.

10. The method according to any of the preceding claims, further comprising the step of washing the treated textile (5) with a washing solution (80) to remove residual TPA salts, the washing solution (80) preferably comprising a dispersant, wherein The bath ratio is in the range of 1 / 2 to 1 / 20, preferably 1 / 7 to 1 / 9, more preferably 1 / 8, based on the weight of the textile relative to the weight of the washing solution.

11. A method according to any preceding claim, wherein: The number of cycles at which the depolymerization solution is fed through the textile is in the range of 30 to 480 cycles / hour, preferably 50 to 400 cycles / hour, more preferably 60 to 300 cycles / hour, most preferably 70 to 300 cycles / hour.

12. A method according to any preceding claim, wherein: The waste textile (1) comprises one or more optical brighteners, and the method further comprises a step of removing the optical brighteners from the textile (1) prior to the deagglomeration step.

13. A method according to any preceding claim, wherein: The textile is selected from fibers, yarns, fabrics and garments, preferably from fabrics and garments, the garments optionally comprising non-textile elements including zippers, buttons and rivets, wherein, after carrying out the method, the non-textile elements are detached from the garments and removed from the garments.

14. A method according to any preceding claim, wherein: Any one of the depolymerization solution, bleaching solution and washing solution is adjusted to its initial concentration and reused 1 to 100 times, preferably 10 to 100 times, more preferably 10 to 40 times in subsequent depolymerization, bleaching or washing cycles for new batches of waste mixed textiles.

15. An apparatus (100) for carrying out the method for recycling textile waste (1) comprising polyester (4) and cellulose fibers (40) according to any of the preceding claims, characterized in that The device comprises: a closable reaction chamber (10) configured to receive the waste textile (1); at least one tank (7) to hold the depolymerization solution (3), and optionally at least one of a plurality of tanks (7a, 7b) to hold at least one of a bleaching solution (30) and a washing solution (80); a pump (8) for feeding and circulating the depolymerization solution (3) from the depolymerization solution tank (7) into the chamber (10); - Means (90; 9a; 9b) for controlling the temperature of the depolymerization solution (3) in the chamber (10).

16. Apparatus according to claim 15, comprising a filter basket (6) to contain the textile (1) in the chamber, the basket being removable from the chamber (10), preferably the chamber comprising at least one perforated separation element (60) housed in the basket (6) to maintain the textile in a static state.

17. A method for recycling textile waste comprising polyester and cellulose fibers, preferably cotton fibers, selected from garments and fabrics, wherein the garments or fabrics comprise fabric portions sewn together by sewing yarns, the fabric portions consisting of cotton yarns and / or cellulose yarns, preferably 100% cotton fabric portions, the sewing yarns being polyester sewing yarns, the method comprising depolymerizing the polyester yarns in an alkaline aqueous solution, comprising the following steps: a) providing an amount of the textile in a reaction chamber; b) providing an amount of the alkaline depolymerization solution in a range of 1 / 2 to 1 / 20, preferably 1 / 4 to 1 / 8, according to a bath ratio of the textile weight to the solution weight; c) circulating the amount of depolymerization solution through the textile to depolymerize the polyester into corresponding monomers, and removing the polyester monomers from the textile; d) removing the depolymerization solution from the reaction chamber; Wherein, the temperature of the depolymerization solution in step c) is between 101°C and 160°C, and the textile machine is in a static state, the solution circulates through the garment or fabric to provide a treated garment substantially free of polyester material, which includes cellulosic staple fibers, preferably cotton staple fibers.

18. The method according to claim 17, wherein: The garment comprises a non-textile element including a zipper, a button, a label and a rivet, wherein during the method the non-textile element becomes at least partially detached from the garment.

19. The method according to claim 17 or 18, further comprising the features of claim 2 and the features of any one of claims 4 to 14.

20. A polyester-free fabric obtainable by the process according to any one of claims 1 to 14 of depolymerizing the polyester originally present in the fabric, the polyester-free fabric comprising cotton yarns in which empty spaces are provided.

21. The fabric according to claim 20, wherein The degree of polymerization of the cotton fibers of the cotton yarn is between 600 and 3500, so that the cotton fibers can be used for yarn production.

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