Oxidation process for producing regenerated cellulose yarn derived from recycled waste supply raw materials

Abstract

A method for producing cellulose yarn from recycled cellulose material, comprising: (a) dissolving the recycled cellulose material in a solution containing at least a fused ionic liquid, wherein the solution containing the ionic liquid preferably contains less than 5% by weight of a protic liquid; (a1) adding at least one active substance or its precursor to the solution and dissolving and / or dispersing it; (b) adjusting conditions such that the active substance, dissolved or dispersed in the solution containing the fused ionic liquid, or generated in situ in the solution containing the fused ionic liquid, is initially present in the recycled cellulose material and acts to decompose non-cellulose material contained in the solution containing the fused ionic liquid by dissolving the recycled cellulose material; and (c) extruding the fused ionic liquid cellulose material solution through at least one spinning nozzle, wherein the fused ionic liquid cellulose material solution being extruded through at least one spinning nozzle contains less than 5% by weight of a protic liquid, wherein step (a) is preferably carried out at least partially under an oxidizing atmosphere.

Description

[Technical Field]

[0001] The present invention relates to a process for conditioning recycled materials containing cellulose, based on dissolution in an ionic liquid and the addition of an active substance, in order to decompose and remove color and / or alter the molecular weight distribution of the cellulose polymer. The process enables the direct treatment of recycled materials and subsequent spinning into fibers. The process is advantageous in enabling the treatment of a wide range of post-consumer and post-industrial recycled articles for reuse in the production of regenerated cellulose fibers. [Background technology]

[0002] While recycling in the textile sector is becoming increasingly important, its implementation and impact are still far from reaching its ultimate potential. In reality, most recycled textiles are not recycled back to the same level (like-to-like), but rather are downgraded to lower-level uses after recycling, such as building materials (insulation). Ideally, there is a need to provide a circular method that enables textile recycling so that recycled materials can be reused at the highest possible level, so that recycled materials can be produced to create the same type of textile that was used as input for recycling.

[0003] The sustainability profile of regenerated cellulose yarn can be further improved by using cellulose sources based on recycled cellulose raw materials. Examples include post-industrial fabrics and post-consumer apparel such as articles containing cotton, viscose, lyocell, and other forms of cellulose. Additional cellulose-containing streams (e.g., agricultural waste, lignocellulose extract pulp, bacterial cellulose, algal cellulose, etc.) can also be used as cellulose sources.

[0004] Key challenges regarding the use of post-consumer goods include: ○ A wide range of colors using dyes in apparel products. ○ Impurities such as fat, oil, and minerals that adhere to the item during use. ○ Presence of non-cellulose components in the article (e.g., synthetic blend components, sewing threads, surface treatments, fasteners, buttons, etc.) ○ Differences in the molecular weight distribution or degree of polymerization (DP) distribution of cellulose due to differences in polymer origin (for example, cotton has a higher DP compared to cellulose found in late-life textiles such as viscose). It includes.

[0005] Conventional processing techniques to address the above challenges include thorough scouring and bleaching steps that consume a significant amount of water and energy to obtain clean, uncolored cellulose.

[0006] Conventional approaches to removing non-cellulose components include macroscopic mechanical decomposition or selective dissolution of different fibrous components.

[0007] Patent Document 1 discloses how cellulose can be dissolved in an ionic liquid without derivatization and regenerated in various structural forms without the need for the use of harmful or volatile organic solvents. Cellulose solubility and solution properties can be controlled by the selection of ionic liquid components, with small cations and halides or pseudohalide anions assisting the solution.

[0008] Patent Document 2 discloses a regenerated cellulose encapsulation active substance and a method for encapsulating the active substance in a regenerated cellulose matrix. The distribution of the active substance is preferably substantially homogeneous within the regenerated cellulose matrix. The regenerated cellulose (i) has substantially the same molecular weight as the original cellulose from which it is prepared, and (ii) is substantially free of added substituents and substantially free of trapped ionic liquid decomposition products compared to the starting cellulose.

[0009] Patent Document 3 relates to a method for producing a regenerated biopolymer in the form of a carbohydrate using a solvent system containing a dissolved biopolymer. The solvent system is based on a molten ionic liquid and optionally a protic solvent or a mixture thereof. The biopolymer dissolved in the solvent system precipitates in a coagulation medium, the medium containing a protic coagulant or a mixture of protic coagulants. The method according to the invention of Patent Document 3 is characterized in that the surface tension σ of the coagulant or mixture of coagulants, measured according to ASTM D 1590-60 at a temperature of 50°C, is 99% to 30% of the surface tension σ of water. The method according to the invention of Patent Document 3 is economical and flexible and leads to advantageous products, particularly products in the form of staple fibers that are not fibrillated and have an advantageous wet strength-to-dry strength ratio.

[0010] Patent Document 4 proposes a solvent system for biopolymers in the form of carbohydrates based on a molten ionic liquid, in which additives are appropriately present in the solvent system. This solvent system comprises a protic solvent or a mixture of several protic solvents, and when the protic solvent is water alone, it is present in an amount of more than about 5% by weight in the solvent system. Carbohydrates can be incorporated into the solvent system, particularly in the form of starch, cellulose and their derivatives, and the solvent system can then be used to regenerate the carbohydrates dissolved therein. In addition, a particularly advantageous method for producing a solvent system containing carbohydrates and for producing regenerated carbohydrates, particularly in the form of regenerated cellulose fibers, is described. Thus, the invention of Patent Document 4 also provides spun fibers that are not fibrillated. The invention of Patent Document 4 offers economic advantages in particular compared to prior art systems.

[0011] Patent Document 5 discloses a method for recovering waste textiles with the help of an ionic liquid. The method includes the following steps: 1) Pretreatment of waste textiles: The waste textiles are crushed to obtain pretreated waste textiles; 2) Water swelling and dissolution in an ionic liquid: The pretreated waste textiles, the ionic liquid, and water are mixed and stirred under vacuum conditions to obtain a liquid containing cellulose. After the waste textiles are pretreated and swelled in water, the dissolution process is uniform and gentle, the dissolution efficiency is high, the effect is good, and the waste textiles are completely separated from the insoluble material. The cellulose solution obtained by dissolution can be used to prepare a regenerated cellulose material with excellent performance, and the polyester obtained by separation can be used as a recycled polyester raw material.

[0012] Patent Document 6 presents a process for producing cellulose filaments or films, comprising the steps of: dissolving a cellulose substrate in an ionic liquid comprising a superbase cation 7-methyl-1,5,7-triazabicyclo[4.4.0]deca-5-enium[mTBDH]+ and an anion, for the purpose of producing a solution for generating spinning dope, wherein the anion is derived from an acid present in stoichiometric excess relative to the superbase; extruding the spinning dope from the solution through a spinneret into a coagulation bath containing water to form a filament or film; removing the ionic liquid in an aqueous mixture containing water from the coagulation bath; recovering the ionic liquid [mTBDH][OAc] from the aqueous mixture by removing the water; and optionally recycling the recovered ionic liquid to the dissolution step.

[0013] Patent Document 7 discloses a method and system for using a mixed textile feedstock that may include post-consumer waste clothing, scrap fabric, and / or other textile materials as raw feed materials to produce isolated cellulose and other isolated molecules having desirable characteristics that can be used in the textile and apparel industries, as well as other industries. A multi-stage process is provided where the mixed textile feed material is subjected to one or more pretreatment stages followed by at least two pulping processes to isolate cellulose molecules and other molecular components such as polyester. The isolated cellulose and polyester molecules can be used in various downstream applications. In one application, the isolated cellulose and polyester molecules are extruded to provide regenerated cellulose fibers and regenerated polyester fibers having desirable (and selectable) characteristics that can be used in various industrial applications including textile manufacturing.

Prior Art Documents

Patent Documents

[0014]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Patent Document 7

Summary of the Invention

[0015] The object of the present invention is to provide an improved method for producing cellulose yarn from recycled cellulose material.

[0016] The object of the present invention is the corresponding improved method described in claim 1.

[0017] Specifically, the present invention is a method for producing cellulose yarn from recycled cellulose material, (a) A step of dissolving a recycled cellulose material in a solution containing at least a fused ionic liquid, wherein the solution containing the ionic liquid preferably contains less than 5% by weight of a protic liquid, (a1) Adding at least one active substance or its precursor to the solution and dissolving and / or dispersing it, (b) The steps of adapting the conditions (for example, by heating, UV, VIS, IR or other radiation, or by pressure changes) such that the active substance, which is dissolved or dispersed in a solution containing a molten ionic liquid, or which is generated in situ in a solution containing a molten ionic liquid, is initially present in the recycled cellulose material and acts to decompose the non-cellulose material contained in the solution containing the molten ionic liquid by dissolving the recycled cellulose material, (c) A step of extruding a fused ionic liquid cellulose material solution through at least one spinning nozzle, wherein the fused ionic liquid cellulose material solution being extruded through at least one spinning nozzle contains less than 5% by weight of a protic liquid. This includes methods.

[0018] Surprisingly, contrary to expectations, it was found that a protic liquid content of less than 5 weight percent of the ionic liquid cellulose material solution at the moment of extrusion was possible and acceptable.

[0019] Generally, when we speak of the presence of a protic liquid below a certain value, in this context, this means that a protic liquid is present in the corresponding solution, and therefore, it should be noted that the expression should be interpreted as excluding situations where a protic liquid is not present.

[0020] The solution containing at least one fused ionic liquid used in step (a) may be a fresh ionic liquid or an ionic liquid recycled from the process. As stated, preferably, the initial fused ionic liquid in step (a) and / or the fused ionic liquid solution produced by step (a) and / or step (a1) and / or step (b) preferably contain less than 5 weight percent of protic liquid. However, higher percentages are also possible, provided that during the extrusion in step (c), the protic liquid content in the ionic liquid solution is ensured to be less than 5 weight percent.

[0021] It should be noted that in many cases, for example, when hydrogen peroxide is used, the active substance in step (b) releases water, further increasing the water content of the initial solution obtained in step (a) and / or (a1). The protic liquid content in the corresponding solution can be adjusted by degassing (e.g., by applying low pressure or vacuum), which also removes protic liquids, particularly water, contained in the solution. This is possible to establish a desired protic liquid content, i.e., to establish a desired protic liquid content in the initial molten ionic liquid as the starting material in step (a), especially when using a molten ionic liquid recycled from the same process, or to control the protic liquid content further downstream in the process. In particular, it can be used to adjust the conditions of step (c) where a specific protic liquid content is required.

[0022] Here, the active substance acts to decompose the non-cellulose material initially present in the recycled cellulose material. This is in contrast to the solutions of prior art, for example, in International Publication No. 2021 / 234226, only substances that react with ionic liquids are used.

[0023] Here, an ionic liquid bath is used to simultaneously decompose non-cellulose components and prepare the spinning process. This is in contrast to the solutions of the prior art, for example, in International Publication No. 2017 / 019802, where the ionic liquid is used only in an intermediate step in the preparation of cellulose-based material for spinning, and separate steps of pretreatment and dissolution exist, but no active substance is used to decompose the non-cellulose material in the ionic liquid. In any case, pulping agents are not typically used in the processes proposed herein, whereas this is important in the process of International Publication No. 2017 / 019802.

[0024] Therefore, according to yet another preferred embodiment, the method includes, prior to step (c), reducing the protic liquid content in the fused ionic liquid cellulose solution to a desired level, for example, by degassing, particularly if the protic liquid is water.

[0025] Preferably, step (a) is carried out at least partially under an oxidizing atmosphere.

[0026] According to a first preferred embodiment, the oxidizing atmosphere in step (a) is an oxygen-containing atmosphere, more preferably air, and more preferably atmospheric conditions.

[0027] According to yet another preferred embodiment, 30 g / m 3 Humidity below 15 g / m² is preferable. 3 Humidity less than zero, most preferably zero or 10 or 5 g / m² 3 Oxidizing atmosphere with humidity below a certain level.

[0028] Preferably, the exposure to the oxidizing atmosphere in step (a) is carried out for a period of time of at least 10 minutes, preferably at least 30 minutes, or within the range of 40 to 300 minutes, or within the range of 60 to 120 minutes.

[0029] Typically, exposure is carried out under ambient temperature conditions.

[0030] Oxidation as a chemical reaction is a function of temperature and time, and its kinetics are also controlled by temperature. Therefore, given conditions of temperature and time apply equally to situations where equivalent oxidation occurs, for example, at lower temperatures over longer periods of time, or at higher temperatures over shorter periods of time.

[0031] In fact, surprisingly, and contrary to expectations, it was found that maintaining a mixture of cellulose in an ionic liquid under an oxidizing atmosphere had a beneficial effect, leading to the initial decomposition of cellulose. Unexpectedly, neither the ionic liquid, nor the cellulose, nor the subsequent treatment with the activator were adversely affected by exposure of the cellulose-containing ionic liquid to an oxidizing atmosphere. In fact, the opposite was true: the oxidizing environment during or after the mixing and dissolution processes initiated the oxidative decomposition of cellulose, further preparing it for subsequent treatment with the activator. It had been thought that exposure to an oxidizing agent would be problematic for the stability of the ionic liquid, but this proved incorrect.

[0032] This exposure to an oxidizing atmosphere can be carried out simply by exposing the corresponding container with the liquid on its surface to the oxidizing atmosphere, but it can also be enhanced by actively stirring the solution under this atmosphere, and the process can be further forcibly accelerated by bubbling the oxidizing atmosphere into the solution. It is also possible to circulate the ionic liquid cellulose solution through a specific gas / liquid mixing device to increase the efficiency of the process.

[0033] In the context of this disclosure, the terms “atmospheric pressure” and “ambient temperature” refer to the pressure and temperature conditions to which the reactor is typically exposed, namely, typically atmospheric pressure refers to a pressure in the range of 0.8 to 1.1 bar (absolute pressure), and typically ambient temperature refers to a temperature in the range of 10 to 60°C, more typically 20 to 35°C. The gas mixture used as the input to the process is preferably ambient atmospheric air, i.e., air at ambient atmospheric pressure and ambient temperature, which usually means a CO2 concentration in the range of 0.03 to 0.06 volume%. However, air with lower or higher CO2 concentrations, e.g., air with a concentration of 0.1 to 0.5 volume%, can also be used as the input to the process, and therefore, generally speaking, the input CO2 concentration of the input gas mixture is preferably in the range of 0.01 to 0.5 volume%. The oxidizing atmosphere is a gas containing oxidizing species, preferably oxygen. Typically, the oxidizing species are present in the oxidizing atmosphere at a percentage of at least 10%, preferably at least 15%, or in the range of 15 to 99%. As stated, the oxidizing atmosphere is preferably air, i.e., a mixture of 20-25% oxygen with nitrogen and less than 1% of other gases added. This composition is present at least at the beginning of exposure of the ionic liquid solution to that oxidizing atmosphere when speaking of air as an oxidizing atmosphere, and during the process, the oxygen content in the oxidizing atmosphere may decrease due to oxygen consumption.

[0034] Regenerated cellulose yarn produced using ionic liquids (ILs) offers attractive fiber properties and a better sustainability profile (e.g., lower global warming potential, energy use, and biodegradability) compared to fibers made from synthetic polymers such as polyester and polyamide.

[0035] Conventional approaches to address the aforementioned critical challenges for recycling would involve separate, preceding processing steps, distinct from the preparation of ionic liquid cellulose dope and subsequent fiber spinning.

[0036] The approach presented herein provides means for directly processing recycled cellulose-containing articles in a medium containing an ionic liquid in order to achieve the following: • Direct dissolution of recycled cellulose-containing articles for preparing dopes for subsequent fiber spinning. • Dissolution acts first to separate insoluble components, such as synthetic fibers and minerals. • An active substance dispersed in an ionic liquid (or generated in situ) acts to decompose a variety of cellulose-related dyes, as well as fats and other organic impurities. • The absorbent (inert and inorganic) is homogeneously dispersed in the IL, allowing it to specifically absorb impurities, such as dyes and other undesirable components. The loaded absorbent can be filtered out of the cellulose-IL solution and reused after a suitable regeneration process.

[0037] The active substance may also be selected to reduce the molecular weight of the cellulose polymer chain to support subsequent fiber spinning. This reduction in molecular weight can be achieved by exposure to short-wavelength radiation, such as UV light, or by photocatalysis in the presence of a catalyst.

[0038] Following the dissolution of the cellulose material in an ionic liquid and exposure to an oxidizing atmosphere, an active reagent (e.g., hydrogen peroxide and / or enzyme and / or catalyst salt) is added, and the mixture is heated to a temperature between 40 and 120°C while being stirred, and held at this temperature for 0.5 to 24 hours to achieve the desired decolorization. The resulting solution can then be heated / cooled to achieve the desired target temperature and can then be used directly in the fiber spinning process.

[0039] Key advantages of the proposed method include: 1. Removal of various dyes by special absorbents in an ionic liquid treatment medium that can be directly used for decomposition and / or subsequent fiber spinning. This makes it possible to produce fresh, uncolored yarn using a wide range of recycled sources. 2. Breakdown of fats, oils, and other organic impurities that would normally affect yarn quality. 3. Selective dissolution of cellulose and separation of insoluble components (e.g., synthetic polymer components, mineral substances). 4. Direct treatment in an ionic liquid medium used for subsequent fiber spinning avoids the thorough conventional pretreatment steps that would normally require intensive water and energy use, further improving the sustainability profile of the recycling pathway. The resulting treatment pathway requires fewer treatment steps and enables more direct utilization of recycled waste materials containing cellulosic components. 5. The use of ionic liquids and fiber spinning processes described in International Publication No. 2007 / 076979 and International Publication No. 2009 / 062723 (including its disclosure) provides a basis for achieving advantageous regenerated cellulose fibers using ionic liquids resistant to the significant presence of protic components, including water. The process advantageously enables pretreatment active substances that achieve in situ decolorization and impurity decomposition / absorption without affecting subsequent fiber spinning. Otherwise, this pretreatment would not be possible with ionic liquid systems and fiber spinning processes that are less resistant to moisture. 6. The use of catalytic chemistry (enzymes, ozone, short-wavelength radiation) instead of the stoichiometric chemistry (e.g., NaOH) currently used to adjust the degree of polymerization (DP) of cellulose, and the in situ generation of H2O2 in close proximity to the bleaching agent, reduces the amount of H2O2 required for the bulk phase dosing, and consequently reduces the amount of chemicals needed.

[0040] One of the key features of the present invention is that, surprisingly, ionic liquids can be used for dissolving cellulose and active substances under an oxidizing atmosphere, and have been found to be able to withstand a certain amount of water or other protic solvents for cellulose dissolution and spinning while achieving excellent fiber properties, and at the same time, enabling the introduction of catalytic components without raising the level of water or other protic solvents to a level that would adversely affect proper fiber spinning and thus fiber properties.

[0041] Decomposition / absorption of dyes and organic impurities is possible as follows: • Bleaching / decolorization of dyes related to direct recycled cellulose in an ionic liquid medium used to dissolve cellulose components. Possible approaches include: Addition of organic (inorganic) absorbents that can be filtered out after absorption of impurities and used in a recycling process. Addition of hydrogen peroxide or ozone to an ionic liquid solution of cellulose, or exposure to short-wavelength light or photocatalytic action, In situ production of bleaching active substances such as hydrogen peroxide by adding enzymes to an ionic liquid solution of cellulose (e.g., cellobiose dehydrogenase for localized production of H2O2, but also peroxidase can take up H2O2 and produce radicals that can bleach), Addition of enzymes, such as laccase, to decolorize and destroy impurities. In any case, hydrogen peroxide decomposes into residual water (ionic liquid processes are resistant to the presence of residual water), oxygen, and uncolored residual decomposition byproducts. The residual byproducts may optionally be removed without decomposition or directly by the use of a post-decomposition sorbent in contact with the ionic liquid processing medium.

[0042] Lowering the molecular weight of cellulose is advantageous and can be done as follows: The molecular weight of the cellulose polymer directly affects the process of fiber spinning and the mechanical properties of the resulting yarn. • For some recycled cellulose raw materials (e.g., cotton-rich apparel), it may be advantageous to reduce the molecular weight distribution of cellulose to enable fiber spinning and improve fiber properties. • Homogenization of DP from different flows into a more constant DP cellulose flow to improve spinning process stability and ensure more steady-state process conditions. • A decrease in molecular weight can occur by the action of hydrogen peroxide alone, and / or by the addition of other components selected to cleave the cellulose polymer and consequently reduce the average molecular weight, such as ozone, UV light, or photocatalytic action. Such additives may include enzymes and / or salts. The action of such additives in an ionic liquid medium is facilitated by the presence of water in the ionic liquid, which is one feature of International Publication No. 2007 / 076979 and International Publication No. 2009 / 062723 (in which disclosure is included).

[0043] The use of enzymes (e.g., laccase) to decolorize dyes is an established technique in detergents and laundry processes. The use of active substances, such as enzymes, to achieve a decolorizing effect in an ionic liquid treatment medium is a novel feature of the present invention.

[0044] The use of hydrogen peroxide in an ionic liquid for the oxidative conversion of lignocellulosic feedstocks is described in U.S. Patent No. 10724060, but the patent teaches that the action of hydrogen peroxide targets the decomposition of lignin and does not address the decomposition of color components such as dyes associated with recycled cellulose materials. U.S. Patent No. 10724060 also describes the use of cellulase and / or hemicellulase, but the enzymatic components are specifically selected to convert biomass from cellulose to sugar components rather than reducing the molecular weight while maintaining the properties of the cellulose polymer. It is important to note in U.S. Patent No. 10724060 that the oxidizing substance and the enzymatic substance are brought into contact in an aqueous medium before the subsequent process step for adding the ionic liquid.

[0045] International Publication No. 2016 / 087186 and U.S. Patent No. 8445704 describe the use of ionic liquids as processing media for the chemical modification and transformation of polysaccharides, but hydrogen peroxide / ozone, short-wavelength radiation, photocatalysis and / or enzymes are not used to address color and impurities or the molecular weight of cellulose.

[0046] U.S. Patent No. 11168196 describes an approach to facilitate the separation of blended cellulose / polyester waste, but it does not provide provisions for proactively addressing color, impurities, and / or molecular weight in the ionic liquid used to dissolve the cellulose component.

[0047] The conditions in step (b) can be adapted in different ways, for example, by changing the solvent composition, by adding the active substance (alone or in a carrier solvent), by activating the active substance, by changing the temperature, pH, or pressure, or by introducing activation energy, for example, by radiation, or in combination of such adaptations.

[0048] In the context of (b), the term "active substance" includes suitable substances that are appropriate for performing the function of breaking down the non-cellulose material initially present in recycled cellulose material, examples of which are further shown below.

[0049] The recycled cellulose material is preferably selected from at least one of cellulose-containing streams such as waste, recycled yarn, recycled fabric, recycled tissue, and recycled clothing.

[0050] Non-cellulose materials are typically selected from at least one of the following: non-cellulose materials containing non-cellulose fibers (e.g., PET, PA, elastane, PE, etc., or mixtures thereof), dyes, fats and other organic impurities including oils, waxes and detergent residues, sand or clay, and inorganic substances such as water-soluble and water-insoluble pigments.

[0051] After step (a) and before or after step (b), there may be, preferably, a step (c) in which insoluble or insoluble impurities or absorbents are separated by dissolving the recycled cellulose material. Preferably, this step includes at least one of filtration, decanting, centrifugation, and sieving.

[0052] The ionic liquid solution preferably contains a protic liquid, preferably water.

[0053] The active substance is preferably selected from the group of cleaving agents, which includes absorbents, biological cleaving agents, physical cleaving agents, and chemical cleaving agents. Preferably, the absorbent is selected from the group of substances that adsorb at least one of dyes, fatty impurities, and other organic impurities. Preferably, the cleaving agent is selected from the group of direct cleaving agents or activatable cleaving agents, preferably activatable cleaving agents activated by irradiation with electromagnetic radiation. The cleaving agent can be selected from the group of enzyme systems, which include proteases, oxidoreductases, amylases, laccases, and lipases, ozone, peroxides, photocatalysts, and combinations thereof. In the examples further shown below, the active substance is hydrogen peroxide or an enzyme such as peroxidase, or a combination thereof. However, this is only one possibility, and the substances described above can perform the function of the active substance complementaryly and / or alternatively to this example using hydrogen peroxide. Preferably, the active substance is a substance that acts as an oxidizing agent and has a bleaching effect, or a decomposing agent, preferably an enzyme system such as peroxidase.

[0054] Preferably, the ionic liquid initially contains, if present, a system for reducing the molecular weight of the cellulose polymer, preferably an enzyme system including cellulase, hemicellulase, or cellulose oxidase, particularly endoglucanase, exoglucanase, or peroxidase, or a cleavage agent activated by electromagnetic radiation, or a strong base, or a system selected from the group thereof, or this system is added to the ionic liquid after step (b) or (c).

[0055] In step (b), the temperature is preferably raised to a range of 40 to 120°C and preferably held at this temperature for a time in the range of 0.5 to 24 hours.

[0056] After step (b) or after step (c), cellulose yarn can be directly spun from cellulose dissolved in an ionic liquid.

[0057] The molten ionic liquid further comprises a protic solvent or a mixture of several protic solvents, and if the protic solvent is simply water, the cellulose dissolved in the molten ionic liquid precipitates in a coagulation medium during or downstream of step (c), the coagulation medium comprising a solvent that does not dissolve the cellulose and is miscible with the molten ionic liquid, preferably the molten ionic liquid comprising a cation generated from a compound containing at least one 5-6 membered heterocyclic ring and a protic solvent, and the process comprises precipitating the dissolved cellulose in the form of carbohydrates in a coagulation medium comprising a solvent that does not dissolve the cellulose and is miscible with the molten ionic liquid. The aforementioned protic solvent is 1) Water as the only protic solvent present in the solution system in an amount of less than 5% by weight, 2) Based on the solution system, at least 0.1% by weight of at least one protic solvent selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, amyl alcohol, and alcohols such as linear and branched alcohols and higher linear and branched alcohols, and 3) Water and at least one protic solvent selected from the group consisting of alcohols, carboxylic acids, or amines, such as methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, amyl alcohol, linear and branched alcohols, and higher linear and branched alcohols. It is selected from the group consisting of the following.

[0058] Suitable systems that act as ionic liquids are, for example, systems such as those described in U.S. Patent No. 8,163,215 or U.S. Patent No. 8,841,441, the disclosures of which are incorporated herein by reference with respect to ionic liquid systems, or as in International Publication No. 03 / 029329.

[0059] The ionic liquid in the context of the present invention is preferably (A) General formula (I): [A] + n [Y] n - (I) [where n represents 1, 2, 3 or 4, and [A] + represents a quaternary ammonium cation, an oxonium cation, a sulfonium cation or a phosphonium cation, and [Y] n - represents a monovalent, divalent, trivalent or tetravalent anion] is a salt of Or, the ionic liquid in the context of the present invention is (B) General formula (II) [A 1 + [A 2 + [Y] n- (IIa) [where n = 2]; [A 1 + [A 2 [A 3 + [y] n- (IIb) [where n = 3]; or [A 1 + [A 2 + [A 3 + [A 4 + [Y] n- (IIc) [where n = 4] is a mixed salt, where [A 1 + 、[A 2 + 、[A​​​​​​​​​​3 ] + and [A 4 ] + is [A] + From the groups described, [Y] are independently selected from each other. n- (A) has the meaning described in (A).

[0060] One possible use is, for example, 1-ethyl-3-methylimidazolium chloride. This is also used in the example, but this is merely one possibility, and the ionic liquid substances described in this general section may act equally on their own, complementary (ionic liquid mixture) and / or alternative to this example using 1-ethyl-3-methylimidazolium chloride. In particular, methylimidazolium-based systems, especially those based on 1-ethyl-3-methylimidazolium, such as fluoride, acetic acid, or dicyanamide, (C2H5)(CH3)C3H3N + 2·N(CN) - Systems based on 1-butyl-2,3-dimethylimidazolium or 1-butyl-3,5-dimethylpyridinium, 1-butyl-3-methylimidazolium, or combinations thereof, such as 1-ethyl-3-methylimidazolium having different anions such as 2, as well as 1-butyl-3,5-dimethylpyridinium bromide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, clearly perform the same function.

[0061] Compounds suitable for the formation of cations [A]+ in ionic liquids are known, for example, in German Patent Application Publication No. 10202838. Such compounds may contain oxygen, phosphorus, sulfur, or especially nitrogen atoms, for example, at least one nitrogen atom, preferably 1 to 10 nitrogen atoms, particularly preferably 1 to 5, most preferably 1 to 3, and especially 1 to 2 nitrogen atoms. Such compounds may optionally also contain further heteroatoms, such as oxygen, sulfur, or phosphorus atoms. Nitrogen atoms are suitable carriers for the positive charge of cations in ionic liquids, from which protons or alkyl groups can then be transferred to anions in equilibrium to form electrically neutral molecules.

[0062] The ionic liquid system also includes, for example, the cationic 1,5,7-triazabicyclo[4.4.0]deca-5-enium[TBDH]+ portion described herein in International Publication No. 2018 / 138416, which is also included herein with respect to ionic liquid systems, and formulas a), b), and c).

[0063] [ka]

[0064] It may also be a single-base system including an anion selected from the group.

[0065] In yet another preferred embodiment, the molten ionic liquid comprises a protic solvent or a mixture thereof, the method comprising precipitating cellulose in a solidifying medium during or downstream of step (c), the protic coagulant or mixture of protic coagulants present in the solidifying medium, the surface tension σ of the protic coagulant or mixture of protic coagulants being 99% to 30% of the surface tension σ of water, and each surface tension being measured at a temperature of 50°C according to ASTM D Measured according to 1590-60, the protic coagulant is preferably selected from 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 2-ethyl-1-hexanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2,3-propanetriol, 2,2-dimethyl-1,5-propanediol, cyclohexanol, diethylene glycol, triethylene glycol, and mixtures thereof, and more preferably the coagulation medium does not contain more than 5% carboxylic acid.

[0066] According to a further aspect of the present invention, the present invention relates to cellulose yarn produced using the above method.

[0067] According to yet another aspect of the present invention, the present invention relates to the use of the above-mentioned cellulose yarn for manufacturing textiles, in particular clothing.

[0068] The manufactured cellulose yarn can be used directly in a variety of textile processes, including texturing; twisting; covered yarn (core-spun yarn); knitting; weaving; seamless; circular knitting with other yarns (cotton, nylon, polyester, polypropylene, cellulose-based materials, wool, silk, polyurethane, etc.); warp knitting; rewinding processes; staple fibers; and nonwoven fabrics. The manufactured cellulose yarn can be used directly in a variety of textile forms, including denim; knitwear; intimates; sportswear; fashion; shoes; sewing thread; upholstery; home textiles; and industrial textiles.

[0069] Further embodiments of the present invention are described in the dependent claims.

[0070] Preferred embodiments of the present invention are described below with reference to the drawings, which are for illustrative purposes only and not to limit thereto. [Brief explanation of the drawing]

[0071] [Figure 1] This is a schematic diagram showing the process steps of a conventional treatment for regenerated cellulose fibers from recycled cellulose, compared to the present invention. [Figure 2] This figure shows the UV / Vis spectra of the doped solution measured before (white circles) and after (5 min square, 30 min diamond, 60 min black circle) the addition of hydrogen peroxide. In this case, the 2-hour oxidation was carried out using an N2 atmosphere. [Figure 3] This figure shows the UV / Vis spectra of the doped solution measured before (white circles) and after (5 min square, 30 min diamond, 60 min black circle) the addition of hydrogen peroxide. In this case, the 2-hour oxidation was carried out using air. [Figure 4] This figure shows the UV / Vis spectra of the doped solution measured before (white circles) and after (5 min square, 30 min diamond, 60 min black circle) the addition of hydrogen peroxide. In this case, the 2-hour oxidation was carried out using an N2 atmosphere. [Figure 5]This figure shows the UV / Vis spectra of the doped solution measured before (white circles) and after (5 min square, 30 min diamond, 60 min black circle) the addition of hydrogen peroxide. In this case, the oxidation was carried out using air for 2 hours. [Modes for carrying out the invention]

[0072] Figure 1 shows a schematic of a conventional pretreatment process for recycled cellulose material, in the upper panel, which involves removing color and impurities, followed by dissolution in an ionic liquid and subsequent fiber spinning. In contrast, the present invention, as shown in the lower panel, involves the direct treatment of color and impurities in an ionic liquid dope, followed by the direct dissolution of recycled cellulose in an ionic liquid under an oxidizing atmosphere, and subsequent addition of activators, enabling subsequent fiber spinning. The present invention allows for a reduction in process complexity and a decrease in energy and water usage compared to conventional processes.

[0073] Regarding the definition of the direct dissolution cellulose spinning process, there is some ambiguity in the application as to whether the definition of lyocell is limited to the use of the solvent N-methylmorpholine-N-oxide (NMMO). Herein, the inventors adopt the definition of lyocell fibers in accordance with EU regulation No 1007 / 2011 of September 27, which defined the nomenclature of textile fibers. There, lyocell fibers are defined as regenerated cellulose fibers obtained by dissolution and, without limitation to NMMO, by an organic solvent (a mixture of organic compounds and water) spinning process that does not involve the formation of derivatives. Methods for producing regenerated fibers using lyocell-type processes are known to those skilled in the art and can be found in numerous publications, such as International Publication No. 2022 / 153170.

[0074] In short, the fiber spinning process typically involves the following steps: a) A step in which the cellulose pulp is cut into pieces less than 4 mm in size (this can be done with a high-speed mixer, ball mill, shredder, etc.). b) A step of preparing a premix by contacting the cut cellulose pulp (<4 mm) with an organic solvent and potentially adding H2O (apparatus selected from the group consisting of a sigma mixer, reactor kneader, wiped film evaporator, etc.). c) A step to homogenize the premix. Premixing is performed by mechanical stirring, which mixes the dope for 0 to 6 hours until a homogeneous solution is obtained. d) A step to remove excess water until the final H2O content is significantly less than 5% (using equipment selected from the group consisting of a sigma mixer, reactor kneader, wiped film evaporator, etc.). e) The doping solution is extruded through a suitable nozzle at a temperature range of 65°C ± 30°C depending on the viscosity of the solution. The extruded solution is subjected to air gap spinning and regenerated in the spinning bath. The spinning bath contains a solvent in water at a concentration ranging from 5 to 30% by weight. The fibers are drawn, optionally cut into stapled fibers, washed, bleached, finished, and dried. [Examples]

[0075] Experimental example, Part 1: Materials and methods The knitted fabric used in this study was made from cellulose fibers (viscose). The knitted fabric was dyed with a reactive dye (Robana Blue Hispasol HEGN).

[0076] The UV / Vis spectra of the experimental solution were measured in a quartz cuvette (Hellma GmbH, Germany) using a U-2000 (Hitachi, Japan) device.

[0077] Bleaching step The experiment consisted of the following three steps: 1. Dope preparation: Dissolve stained cellulose in ionic liquid (IL). 2. Oxidation step: Conditioning of doped solution under different headspace gases. 3. Reaction step: Addition of hydrogen peroxide solution to bleach the cellulose.

[0078] In the first step, 1% cellulose was added to each IL at 114.76 g. To oxidize the cellulose and thus reduce its molecular weight by oxidation, the IL / cellulose mixture was heated and held in a sealable glass vial at 90°C for 2 hours with stirring. A second sample was performed as a negative control, with the air in the headspace replaced by nitrogen. After 2 hours, absorbance was measured using UV / Vis spectroscopy. Following the UV / VIS measurement, 3.47 g of hydrogen peroxide solution (30% H2O2 in water) was added to the mixture at 90°C with stirring. The concentrations after the addition of hydrogen peroxide solution are shown in Table 1.

[0079] [Table 1]

[0080] The doped mixture preparation is characterized by a water content of less than 5% w / w. The addition of hydrogen peroxide defines the start of the reaction. UV / VIS measurements were performed 5 minutes, 30 minutes, and 60 minutes after the start of the reaction.

[0081] Example 1: [EMIM]OAc Using the procedure described above, a spinning solution dope was prepared using 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc; CAS 143314-17-4) as the ionic liquid. The UV / Vis spectra were measured directly before the addition of hydrogen peroxide and at 5, 30, and 60 minutes after the start of the reaction.

[0082] In Figure 2, the [EMIM]OAc / cellulose mixture was oxidized for 2 hours using an N2 atmosphere.

[0083] In Figure 3, the [EMIM]OAc / cellulose mixture was oxidized using air for 2 hours.

[0084] In all cases, bleaching experiments were performed using a 30% hydrogen peroxide solution after the oxidation process.

[0085] Example 2: [EMIM]OPr Using the procedure described above, a spinning solution dope was prepared using 1-ethyl-3-methylimidazolium propionate ([EMIM]OPr; CAS 865627-64-1) as the ionic liquid. The UV / Vis spectra were measured directly before the addition of hydrogen peroxide and at 5, 30, and 60 minutes after the start of the reaction.

[0086] In Figure 4, the [EMIM]OPr / cellulose mixture was oxidized for 2 hours using an N2 atmosphere.

[0087] In Figure 5, the [EMIM]OPr / cellulose mixture was oxidized using air for 2 hours.

[0088] In all cases, bleaching experiments were performed using a 30% hydrogen peroxide solution after the oxidation process.

[0089] result: Direct addition of hydrogen peroxide to a cellulose-doped mixture dissolved in an ionic liquid results in a significant and rapid decomposition of color, as measured by UV / vis absorbance at a wavelength of 640 nm (Table 2).

[0090] Color decomposition proceeds rapidly under both air and nitrogen headspace conditions, with the color being clearly removed from the cellulose mixture within a contact time of 5 to 30 minutes.

[0091] [Table 2]

[0092] Experimental example, part 2: Materials and methods The knitted fabric used in this study was made from cellulose fibers (viscose). The knitted fabric was dyed with a reactive dye (Robana Blue Hispasol HEGN).

[0093] The UV / Vis spectra of the experimental solution were measured in a quartz cuvette (Hellma GmbH, Germany) using a U-2000 (Hitachi, Japan) device.

[0094] A hydrogen peroxide solution (5% in citrate buffer) was prepared from a 30% starting solution (Carl Roth).

[0095] A horseradish peroxidase (Carl Roth; >250 U / mg) solution was prepared at a final concentration of 0.176 g / L (in citrate buffer, pH=5).

[0096] Decolorization step (enzyme) The experiment involved the following two steps: 1. Dope preparation: Dissolve stained cellulose in ionic liquid (IL). 2. Reaction step: Addition of hydrogen peroxide solution and / or peroxidase solution to the cellulose / IL mixture.

[0097] In the first step, 1% of cellulosic fiber (0.15 g) was added to 14.3 g of 1-ethyl-3-methylimidazolium propionate ([EMIM]OPr; CAS 865627-64-1) as an ionic liquid. The IL / cellulose mixture was heated and the solution was kept at 45°C for at least 1 hour while stirring in a sealable glass vial. Two reference samples were prepared by adding either 600 μL of hydrogen peroxide solution or 600 μL of peroxidase solution alone. A test sample was prepared by adding 600 μL of hydrogen peroxide solution in combination with 600 μL of peroxidase solution. The samples were stirred for 16 and 65 hours, followed by absorbance measurements by UV / Vis spectroscopy.

[0098] result: Direct addition of a combination of hydrogen peroxide and peroxidase to a doped mixture of cellulose dissolved in an ionic liquid resulted in significant color degradation, as measured by UV / vis absorbance at a wavelength of 640 nm (Table 2). Enzyme activity was observed to be conserved in IL, and the hydrogen peroxide + peroxidase combination resulted in more rapid color degradation compared to blank samples with hydrogen peroxide alone or peroxidase alone.

[0099] [Table 3]

Claims

1. A method for producing cellulose yarn from recycled cellulose material, (a) A step of dissolving the recycled cellulose material in a solution containing at least a fused ionic liquid, wherein the solution containing the fused cellulose material and the ionic liquid preferably contains less than 5% by weight of a protic liquid. (a1) Adding at least one active substance or its precursor to the solution and dissolving and / or dispersing it, (b) The steps of adjusting the conditions such that the active substance, which is dissolved or dispersed in the solution containing the fused ionic liquid, or which is generated in situ in the solution containing the fused ionic liquid, is initially present in the recycled cellulose material and acts to decompose the non-cellulose material contained in the solution containing the fused ionic liquid by dissolving the recycled cellulose material, (c) A step of extruding a fused ionic liquid cellulose material solution through at least one spinning nozzle, wherein the fused ionic liquid cellulose material solution being extruded through at least one spinning nozzle contains less than 5% by weight of a protic liquid. Methods that include...

2. At least step (a) is carried out at least partially under an oxidizing atmosphere, preferably the oxidizing atmosphere in step (a) is an oxygen-containing atmosphere, more preferably air, more preferably atmospheric conditions, and more preferably 30 g / m³ ３ Humidity less than 15 g / m², more preferably 15 g / m² ３ Humidity less than zero, most preferably zero, 10, or 5 g / m² ３ The method according to claim 1, wherein the humidity is less than [amount missing].

3. The method according to claim 2, wherein the exposure to the oxidizing atmosphere in step (a) is performed for a period of time of at least 10 minutes, preferably at least 30 minutes, or within the range of 40 to 300 minutes, or within the range of 60 to 120 minutes.

4. The method according to any one of claims 1 to 3, wherein the recycled cellulose material is selected from at least one of other cellulose streams, including cellulose waste, recycled yarn, recycled fabric, recycled tissue, recycled clothing, and cellulose-containing waste streams.

5. The method according to any one of claims 1 to 4, wherein the noncellulose material initially contained in the non-recyclable cellulose material is selected from at least one of the following noncellulose materials, the noncellulose material may be noncellulose fibers, dyes, fats, and other organic impurities including oils, waxes, and detergents and their residues, as well as inorganic substances including sand, clay, water-soluble and water-insoluble pigments.

6. The method according to any one of claims 1 to 5, wherein after step (a) and before or after step (b), there is a step (c) of separating insoluble or insoluble impurities or absorbents by the dissolution of the recycled cellulose material, preferably the step comprising at least one of filtration, decanting, centrifugation, and sieving.

7. The method according to any one of claims 1 to 6, wherein the solution containing the ionic liquid contains less than 4.5%, or less than 4%, or less than 3.5% by weight of a protic liquid, preferably in the form of water.

8. The method according to any one of claims 1 to 7, wherein the active substance is selected from the group of cleaving agents, which include absorbents, biological cleaving agents, physical cleaving agents and chemical cleaving agents, preferably the absorbent is selected from the group of substances that adsorb at least one of dyes, fatty impurities and other organic impurities, preferably the cleaving agent is selected from the group of direct cleaving agents or activatable cleaving agents, preferably activatable cleaving agents activated by irradiation with electromagnetic radiation, and the cleaving agent can be selected from the group of enzyme systems including proteases, amylases, laccases, oxidoreductases and lipases, ozone, peroxides, particularly hydrogen peroxide, photocatalysts, and combinations thereof.

9. The method according to any one of claims 1 to 8, wherein the solution containing an ionic liquid initially includes, if present, a system for reducing the molecular weight of a cellulose polymer, preferably an enzyme system comprising cellulase or hemicellulase or cellulose oxidase, particularly exoglucanase and / or endoglucanase, or a cleavage agent activated by electromagnetic radiation, or a strong base, or a system selected from the group thereof, or the system is added to the solution after step (b) or (c).

10. The method according to any one of claims 1 to 9, wherein in step (b), the temperature is raised to a range of 40 to 120°C, and preferably maintained at the temperature for a time range of 0.5 to 24 hours.

11. The method according to any one of claims 1 to 10, wherein after step (b) or after step (c), the cellulose yarn is directly spun from the cellulose dissolved in the solution containing the ionic liquid.

12. The molten ionic liquid comprises a protic solvent or a mixture of several protic solvents, wherein the protic solvent is simply water and present in the solution system in an amount of less than 5% by weight, the cellulose dissolved in the molten ionic liquid precipitates in the coagulation medium during or downstream of step (c), the coagulation medium comprises a solvent that does not dissolve the cellulose and is miscible with the molten ionic liquid, preferably the molten ionic liquid comprises a cation generated from a compound containing at least one 5-6 membered heterocyclic ring and a protic solvent, and the process comprises precipitating the dissolved cellulose in the form of carbohydrates in a coagulation medium comprising a solvent that does not dissolve the cellulose and is miscible with the molten ionic liquid, and / or, the molten ionic liquid comprises a protic solvent or a mixture thereof, the method comprising precipitating the cellulose in a solidifying medium during or downstream of step (c), a protic coagulant or a mixture of protic coagulants present in the solidifying medium, the surface tension σ of the protic coagulant or the mixture of protic coagulants being 99% to 30% of the surface tension σ of water, and each surface tension being measured at a temperature of 50°C according to ASTM D 1590-60. The method according to any one of claims 1 to 11.

13. The method according to any one of claims 10 to 12, wherein the protic coagulant is selected from 1-hexanol, 1-heptanol, 1-octanol, 1-nonanol, 1-decanol, 1-undecanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, 2-ethyl-1-hexanol, 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2,3-propanetriol, 2,2-dimethyl-1,5-propanediol, cyclohexanol, diethylene glycol, triethylene glycol, and mixtures thereof, and more preferably the coagulation medium does not contain more than 5% carboxylic acid.

14. A cellulose yarn produced using the method described in any one of claims 1 to 13.

15. Use of the cellulose yarn according to claim 14 for manufacturing textiles, particularly garments, preferably directly used in textile processes including texturing; twisting; covered yarn; knitting; weaving; seamless; circular knitting; warp knitting; rewinding processes; staple fibers; and nonwoven fabrics with other yarns including cotton, nylon, polyester, polypropylene, cellulose-based materials, wool, silk, and polyurethane, wherein the textile is preferably selected from the group of denim; knitwear; intimates; sportswear; fashion; shoes; sewing threads; upholstery; home textiles; and industrial textiles. use.

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