Process for fabrication of cellulose yarns derived from cellulose feedstocks

Abstract

Method for the production of cellulose yarns from a feedstock cellulose material, and yarns obtained using said method, wherein the method comprises the following steps: (a) dissolution of the feedstock cellulose material in a solution containing at least a molten ionic liquid, wherein the solution containing ionic liquid with dissolved cellulose material comprises a protic liquid in an amount of less than 5 wt. % and wherein at the end of dissolution the solution containing ionic liquid with dissolved cellulose material and a protic liquid is at a temperature in the range of 50-120°C; (b) maintaining the solution containing ionic liquid with dissolved cellulose material and a protic liquid at a temperature in the range of 40-95°C for a time span in the range of 3-18 hours essentially without stirring; (c) extruding the solution containing ionic liquid with dissolved cellulose material and a protic liquid through at least one spinning nozzle, wherein the solution containing ionic liquid with dissolved cellulose material and a protic liquid during extrusion through at least one spinning nozzle comprises a protic liquid in an amount of less than 5 wt. %.

Description

[0001] TITLE

[0002] PROCESS FOR FABRICATION OF CELLULOSE YARNS DERIVED FROM CELLULOSE FEEDSTOCKS

[0003] TECHNICAL FIELD

[0004] The present invention relates to a process for conditioning cellulose feedstock, including recycled materials containing cellulose, based on dissolution in ionic liquids and, if needed, addition of active substances to degrade and remove colors and / or if needed modify the molecular weight distribution of the cellulose polymers. The process enables direct processing of recycled materials and subsequent spinning into high tenacity low fibrillation fibers. Also, the invention relates to high-tenacity, high-elongation, low-fibrillation fibres, in particular such fibres obtained using such a process.

[0005] PRIOR ART

[0006] Recycling in the textile field has become increasingly important, however its implementation and impact remains far from reaching its ultimate potential. In fact, most of the recycled textiles are not recycled to the same level again (like to like), but rather used after recycling for low level applications, e.g. for use as construction materials (insulation), et cetera (downgrading). There is a need to provide for circular methods which allow the recycling of textiles in a way which allows the recycled material to be reused at an as high as possible level, ideally for producing the same kind of textiles as used as input for the recycling.

[0007] The sustainability profile of regenerated cellulose yarns can be further improved when cellulose sources based on recycled cellulose raw materials are used. Examples include post-industrial fabrics and post-consumer apparel such as articles that contain cotton, viscose, lyocell and other forms of cellulose. Additional cellulose-containing streams (e.g. agricultural waste, lignocellulose extracted pulp, bacteria-derived cellulose, algae-derived cellulose etc.) may also be used as sources of cellulose.

[0008] Key challenges of using post-consumer articles include the following: o Wide assortment of colors due to dyestuffs in apparel items; o Impurities such as fats, oils, mineral matter picked up during the use of the articles; o Presence of non-cellulose components in the articles (e.g. synthetic blend components, sewing thread, surface treatments, zippers, buttons etc.). o Different distribution of cellulose molecular weight distribution or degree of polymerization (DP), due to the different origin of the polymer (e.g. cotton has. A larger DP compared with man-made cellulosic that might be found in end of life textiles based on viscose yarns). Conventional processing techniques to address the above challenges involve intensive scouring and bleaching steps that involve significant consumption of water and energy to provide clean and color-free cellulose.

[0009] Conventional approaches to remove non-cellulose components involve mechanical disassembly for macro items or selective dissolution for different fiber components.

[0010] WO-A-03029329 discloses how cellulose is dissolved in an ionic liquid without derivatization, and is regenerated in a range of structural forms without requiring the use of harmful or volatile organic solvents. Cellulose solubility and the solution properties can be controlled by the selection of the ionic liquid constituents, with small cations and halide or pseudohalide anions favoring solution.

[0011] WO-A-2004084627 discloses a regenerated cellulose-encapsulated active substance and a method for encapsulating an active substance in a regenerated cellulose matrix. The distribution of the active substance is preferably substantially homogeneous within the matrix of regenerated cellulose. The regenerated cellulose (i) has about the same molecular weight as the original cellulose from which it is prepared (ii) is substantially free of added substituent groups relative to the starting cellulose and is also substantially free of entrapped ionic liquid degradation products.

[0012] WO-A-2009062723 relates to a method for producing regenerated biopolymers in the form of carbohydrates, using a solvent system that contains the biopolymers dissolved therein. The solvent system is based on a melted ionic liquid and optionally a protic solvent or a mixture thereof. The biopolymers dissolved in the solvent system are precipitated in a coagulation medium, said medium comprising a protic coagulant or a mixture of protic coagulants. The method according to the invention is characterized in that the surface tension o of the coagulant or the mixture of coagulants is 99% to 30% of the surface tension o of water, the surface tension being measured according to ASTM D 1590-60 at a temperature of 50° C. The method according to the invention is economical and flexible and leads to advantageous products, especially in the form of staple fibers which are especially not fibrillated and have an advantageous wet to dry strength ratio.

[0013] WO-A-2007076979 proposes a solvent system for biopolymers in the form of carbohydrates which is based on a molten ionic liquid, with additives being present in the solvent system if appropriate. This solvent system comprises a protic solvent or a mixture of a plurality of protic solvents, and if the protic solvent is water alone, this is present in the solvent system in an amount of more than about 5% by weight. Carbohydrates can be incorporated into the solvent system, in particular in the form of starch, cellulose and derivatives thereof, and the solvent system can then be employed for regenerating the carbohydrates dissolved therein. In addition, a particularly advantageous method of producing the solvent system containing the carbohydrates and for producing regenerated carbohydrates, in particular in the form of regenerated cellulose fibres, is described. The invention accordingly also provides such spinning fibres which are nonfibrillating. The invention offers, in particular, economic advantages over the systems of the prior art.

[0014] CN-A-106146877 discloses a method for recovering waste textile by the aid of an ionic liquid. The method comprises steps as follows: 1) pretreatment of the waste textile: the waste textile is crushed, and pretreated waste textile is obtained; 2) water swelling and dissolution in the ionic liquid: the pretreated waste textile, the ionic liquid and water are mixed and stirred under the vacuum condition, and a liquid containing cellulose is obtained. After the waste textile is pretreated and swollen in water, the dissolution process is uniform and mild, the dissolution efficiency is high, the effect is good, and the waste textile is thoroughly separated from insoluble matters. A cellulose solution obtained through dissolution can be used for preparing a regenerated cellulose material with excellent performance, and polyester obtained through separation can serve as a polyester raw material to be recycled.

[0015] WO-A-2021234226 provides a process for the production of a cellulose filaments or films, comprising the steps of dissolving a cellulose substrate in an ionic liquid consisting of the superbase cation 7-methyl-l,5,7-triazabicyclo[4.4.0]dec-5-enium [mTBDH]+ and an anion to produce a solution forming a spinning dope, said anion being derived from an acid which is present at a stoichiometric excess to the superbase, extruding the spinning dope through a spinneret in a coagulation bath containing water to form filaments or films from the solution, withdrawing ionic liquid in an aqueous mixture with water from the coagulation bath, recovering the ionic liquid [mTBDH][OAc] from the aqueous mixture by removing water and optionally recycling the recovered ionic liquid to the dissolution step.

[0016] WO-A-2017019802 discloses methods and systems which use mixed textile feedstock, which may include post-consumer waste garments, scrap fabric and / or other textile materials as a raw feed material to produce isolated cellulose and other isolated molecules having desirable properties that can be used in the textile and apparel industries, and in other industries. A multi-stage process is provided, in which mixed textile feed material is subjected to one or more pretreatment stages, followed by at least two pulping treatments for isolating cellulose molecules and other molecular constituents, such as polyester. The isolated cellulose and polyester molecules may be used in a variety of downstream applications. In one application, isolated cellulose and polyester molecules are extruded to provide regenerated cellulose fibers and regenerated polyester fibers having desirable (and selectable) properties that are usable in various industrial applications, including textile production.

[0017] WO-A-2023104635 discloses a method for the production of cellulose yarns from recycling cellulose material, wherein the method comprises the following steps: (a) dissolution of the recycling cellulose material in a molten ionic liquid; (b) adapting the conditions such that active substances dissolved or dispersed in the molten ionic liquid or generated in situ in the molten ionic liquid act to degrade non-cellulose material initially contained in the recycling cellulose material and contained in the molten ionic liquid due to the dissolution of the recycling cellulose material, wherein the active substances can already be present during (a) or can be added after (a) and before or during (b).

[0018] SUMMARY OF THE INVENTION

[0019] It is the object of the present invention to propose a new method for the production of cellulose yarns from cellulose feedstock, and to propose high tenacity and high elongation fibres in particular combined with a low fibrillation.

[0020] Object of the present invention is correspondingly a method as claimed and fibers as claimed as well as uses of the fibers as claimed.

[0021] More specifically, according to a first aspect of the invention, it relates to a method for the production of cellulose yarns from a feedstock cellulose material, wherein the method comprises the following steps:

[0022] (a) mixing (including pre-mixing) and dissolution of the feedstock cellulose material in a solution containing at least a molten ionic liquid (or even more generally in an organic solvent), wherein the solution containing ionic liquid with dissolved cellulose material comprises a protic liquid in an amount of less than 5 wt. % and wherein at the end of dissolution the solution containing ionic liquid with dissolved cellulose material and a protic liquid is at a temperature in the range of 50-120°C (this step may include contact with air or no contact with air);

[0023] (b) maintaining the solution containing ionic liquid with dissolved cellulose material and a protic liquid at a temperature in the range of 40-95°C for a time span in the range of 3-18 hours essentially without stirring and preferably essentially without contact with air;

[0024] (c) extruding the solution containing ionic liquid with dissolved cellulose material and a protic liquid through at least one spinning nozzle, wherein the solution containing ionic liquid with dissolved cellulose material and a protic liquid during extrusion through at least one spinning nozzle comprises a protic liquid in an amount of less than 5 wt. %.

[0025] Note that generally when talking about a protic liquid presence of less than a certain value, in the present context this means that there is protic liquid in the corresponding solution, so the wording is to be construed as excluding the situation where there is no protic liquid. The solution containing at least one molten ionic liquid used for step (a) can be fresh ionic liquid or can be ionic liquid recycled from the process. As mentioned, the initial molten ionic liquid for step (a) and / or the molten ionic liquid solution resulting from step (a) and / or step (b) preferably comprises a protic liquid in an amount of less than five weight percent.

[0026] The problems associated with the prior art processes, in particular those as disclosed for example in the above-mentioned document WO-A-2023104635 is the stability of the fibre extrusion process. It was found that no stable extrusion is possible using the information as available in the prior art documents.

[0027] It was then surprisingly found that step (b), i.e. to have a step of maintaining the heated solution with the dissolved cellulose material in a resting state, so essentially without stirring and preferably essentially without contact with air, leads to a stable process. The corresponding resting time is usually implemented by a corresponding buffer tank for realizing step (b), so it is possible to have a first container for mixing and carrying out step (a), the output thereof is then transferred to a buffer container to implement step (b) and output of that buffer container is then used for step (c).

[0028] It was found that using that process sequence enables to carry out a stable extrusion for at least 10 minutes, or at least 20 minutes, or at least 30 minutes or even 2 or more hours. Expressed in terms of length of extruded fibers, this corresponds to a minimum extrusion length of the corresponding fibers of more than 15,000 m, preferably at least 20,000 m or at least 30,000 m (these values are given e.g. for an extrusion speed of 1500 m / min, the extrusion speed can also be higher or lower, e.g. 750 m / min or 500 m / min, and the figures then scale accordingly). Expressed in terms of weight of extruded fiber, this can also be expressed as a minimum weight of extruded fiber of at least 12.5 g (e.g. for 25 dtex, and an extrusion speed expressed in weight of 0.12 g / min), or at least 25 g (e.g. for 50 dtex, and an extrusion speed expressed in weight of 0,25 g / min) or at least 37.5 g (e.g. for 75 dtex, and an extrusion speed expressed in weight of 0,375 g / min).

[0029] As pointed out above, it is preferred to avoid contact with air during the resting step (b), and therefore contact with air in step (b), while the solution is in a resting tank, is preferably avoided. This can be implemented by having an inert gas atmosphere above the liquid solution. This avoids oxidation of the material in the top layers of the liquid in the resting tank, which adds to reducing the stability problems of the extrusion process. When stating that step (b) is carried out "essentially without stirring", this means that except for motion initiated by filling solution obtained in step (a) and motion generated by taking out solution for carrying out step (c) there is preferably no active stirring in step (b) at all, so for example in a corresponding buffer tank. Preferably if there is some fluid movement it is in the laminar flow regime with the fluid experiencing low-shear conditions (defined as lower dimensionless Reynolds number Re < 2000). There can be, in order to provide homogeneous temperature conditions, however a slight stirring in a corresponding buffer tank, the corresponding energy input per unit volume (time average equivalent or continuously at this level) provided by corresponding stirring should however preferably not be above 1 W / m3, preferably not be above 0.5 W / m3, and most preferably not be above 0.1 W / m3.

[0030] According to a preferred embodiment the method includes a step before step (c), which reduces the protic liquid content in the molten ionic liquid cellulose solution to the desired level, e.g. by evaporation and degassing, in particular if the protic liquid is water.

[0031] In step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is preferably maintained at a temperature in the range of 60-90°C, preferably in the range of 70-90°C or 80-90°C.

[0032] Or in step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is preferably maintained for a time span in the range of 5-15 hours, preferably in the range of 7-10 hours.

[0033] During step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is preferably heated to maintain, during step (b), a constant temperature around a fixed value, preferably a fixed value in the range of 75-90°C, with a deviation of less than 10°C, preferably of less than 5°C above and below that fixed value.

[0034] The zero shear viscosity of the solution containing ionic liquid with dissolved cellulose material and a protic liquid preferably is in the range of 1 ,000-50,000 Pa.s at 50°C, preferably in the range of 2,000-10,000 Pa.s at 50°C during step (b). These values were determined with a Rheometer MCR 302e from Anton Paar using a 25 mm plate. A force- controlled frequency sweep was used with frequency range from 100 rad / s to 0.1 rad / s.

[0035] The cellulose content of the solution containing ionic liquid with dissolved cellulose material and a protic liquid during step (b) and / or step (c) is preferably in the range of 2-20% by weight, preferably in the range of 5-18% by weight.

[0036] The protic liquid of the solution containing ionic liquid with dissolved cellulose material and a protic liquid during step (b) and / or step (c) is preferably selected to be, preferably solely, water and the content thereof is in the range of 1.5-4.5% by weight, preferably in the range of 2-4% by weight.

[0037] For step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is preferably maintained essentially without stirring in a storage vessel or a section of a storage tube or cavity, and wherein at least for transferring the solution containing ionic liquid with dissolved cellulose material and a protic liquid into said storage vessel or section of a storage tube, a pump is used, if need be assisted with negative headspace pressure, wherein preferably in the headspace above said solution a pressure in the range of 5-200 mbar, preferably in the range of 10-50 mbar is established.

[0038] For transferring the solution containing ionic liquid with dissolved cellulose material and a protic liquid after step (b) for step (c) to the spinning beam a pump is used, if need be assisted by an inert gas, preferably nitrogen gas, preferably in the atmosphere above the solution containing ionic liquid with dissolved cellulose material and a protic liquid, preferably at an overpressure, in particular in the range of 1.5-4 bars, preferably in the range of 2-3.5 bars.

[0039] For step (c) the temperature of the solution containing ionic liquid with dissolved cellulose material and a protic liquid can be reduced to a value in the range of 70-90°C, preferably in the range of 75-85°C.

[0040] Step (a) can incorporate or be followed by the following steps:

[0041] (a1) adding and dissolving and / or dispersing at least one active substance or a precursor thereof in said solution;

[0042] (a2) adapting the conditions such that said active substances dissolved or dispersed in the solution containing molten ionic liquid or generated in situ in the solution containing molten ionic liquid act to degrade non-cellulose material initially contained in the recycling cellulose material and contained in the solution containing molten ionic liquid due to the dissolution of the recycling cellulose material,

[0043] The approach with active substances provides a means of directly processing recycled cellulose-containing articles in a medium containing ionic liquid to achieve the following:

[0044] • Direct dissolution of recycled cellulose-containing articles to prepare a dope for subsequent fiber spinning;

[0045] • The dissolution firstly acts to separate out the non-soluble components e.g. synthetic fibers, mineral matter;

[0046] • Active substances dispersed in the ionic liquid (or generated in-situ) act to degrade the diverse dyestuffs associated with the cellulose, and also to degrade fatty and other organic impurities;

[0047] • Absorbents (inert and inorganic) may be homogeneously dispersed in the IL to specifically absorb impurities e.g. dyes and other unwanted ingredients. The loaded absorbents are filtered off from the cellulose-IL solution and may be reused after a suitable regeneration process.

[0048] Active substances may also be chosen in such a way to reduce the molecular weight of the cellulose polymer chains to assist in subsequent fiber spinning. Reduction of molecular weight can be achieved through exposure to short wavelength radiation e.g. UV light or photocatalysis in the presence of a catalyst. Following dissolution of the cellulose materials in the ionic liquid and exposure to the oxidative atmosphere the active reagents (e.g. hydrogen peroxide and / or enzymes and / or catalyst salts) are added and the mixture is heated while stirring to a temperature between 40 and 120 °C and maintained at temperature for 0.5 to 24 hours duration to achieve the desired decolorization. The resulting solution may then be heated / cooled to achieve the desired target temperature and then may be used directly to the fiber spinning process.

[0049] Key advantages for the proposed method include:

[0050] 1. Degradation of diverse dyestuffs directly and / or removal by a specific absorbents in the ionic liquid processing medium that can be directly used in subsequent fiber spinning. Enables a wide range of recycled sources to be used to generate fresh non-colored yarn.

[0051] 2. Degradation of fats, oils and other organic impurities that would otherwise impact yarn quality.

[0052] 3. Selective dissolution of cellulose and separation of insoluble components (e.g. synthetic polymer components, mineral matter).

[0053] 4. Processing directly within the ionic liquid medium used for subsequent fiber spinning avoids intensive conventional pre-processing steps that would otherwise require intensive water and energy use, further improving the sustainability profile of the recycling path. The resulting processing path requires less processing steps and enables a more direct utilization of recycled waste materials containing cellulosic components.

[0054] 5. Use of ionic liquids and fiber spinning process as described by W02007076979 and W02009062723 (the disclosure of which is included) provides a basis for achieving favorable regenerated cellulose fibers with ionic liquids that are tolerant to significant presence of protic components including water. The process advantageously enables the pre-processing active substances that provide the in-situ decolorization and impurity degrading / absorbing actions without impacting the performance of the subsequent fiber spinning. This pre-processing would otherwise not be feasible with ionic liquid systems and fiber spinning processes that are less tolerant of water content.

[0055] 6. Use of catalytic chemistry (enzymes, ozone, short wavelength radiation) vs. stoichiometrical chemistry currently used for the adjusting of cellulose degree of polymerisation (DP) (e.g. NaOH), in situ generation of H2O2 in direct proximity to the substances to bleach reduces the amount of H2O2 required vs. a dosing in the bulk phase translates in less chemicals needed.

[0056] Ionic liquids can be used for dissolving under oxidative atmosphere for the dissolution of the cellulose and also for the dissolution or dispersion of active substances, and can tolerate water or other protic solvents up to certain amount for the dissolution of cellulose and spinning while achieving excellent fiber properties, allowing at the same time for the introduction of catalytic components which do not increase the water or other protic solvents levels to a level that would adversely impact proper fiber spinning and consequently the fiber properties.

[0057] Degradation / absorbing of dyestuffs and organic impurities is possible as follows:

[0058] • Bleaching / decolorization of dyestuffs associated with recycled cellulose directly within the ionic liquid medium used to dissolve the cellulose components.

[0059] • Possible approaches include:

[0060] Addition of (in)organic absorbents, which will be filtered off after absorbing the impurities and can be subjected to a recycling process;

[0061] Addition of hydrogen peroxide or ozone to the ionic liquid solution of cellulose or exposed to short wavelength light or photocatalysis;

[0062] In situ generation of bleaching active substances like hydrogen peroxide through addition of enzymes to the ionic liquid solution of cellulose (e.g. cellobiose dehydrogenase for the localized generation of H2O2, but also peroxidases can take H2O2 and produce radicals able to bleach);

[0063] Addition of enzymes e.g. Laccases to decolorize and destroy impurities.

[0064] • In each case the hydrogen peroxide breaks down into residual water (ionic liquid process is tolerant to presence of remaining water), oxygen and non-colored residual degradation by-products. The residual by-products may optionally be removed directly without degradation or through use of sorbent materials after its breakdown in contact with the ionic liquid processing medium.

[0065] Reduction in molecular weight of cellulose is advantageous and possible as follows:

[0066] • The molecular weight of the cellulose polymer has a direct impact on the fiber spinning performance and also the mechanical properties of the resulting yarn;

[0067] • For some recycled cellulose raw materials (e.g. cotton-rich apparel) it may be advantageous to reduce the molecular weight distribution of the cellulose to enable improved rheology, fiber spinning performance and fiber properties;

[0068] • Homogenisation of the DP of different streams to a more constant DP cellulose stream which increases the stability of the spinning process ensuring more steady state process conditions.

[0069] • Reduction of the molecular weight may occur through action of hydrogen peroxide alone and / or with addition of other components e.g. ozone or UV light or photocatalysis selected to cleave the cellulose polymer resulting in reduced average molecular weight;

[0070] • Such additives may include enzymes and / or salts. The action of such additives in the ionic liquid medium is facilitated by the presence of water in the ionic liquid that is a feature of W02007076979 and W02009062723 (the disclosure of which is included).

[0071] The use of enzymes (e.g. Laccases) to decolorize dyestuffs is established art in detergents and laundry processing. The use of active substances like for example enzymes to achieve decolorization effect in ionic liquid processing medium is a new feature of the present invention.

[0072] The use of hydrogen peroxide in ionic liquid for oxidative conversion of lignocellulosic feedstock is described in US10724060 however the patent instructs that the action of the hydrogen peroxide is targeting degradation of lignin - degradation of color components such as dyestuffs associated with recycled cellulose materials is not addressed. US10724060 also mentions use of cellulases and / or hemicellulases however the enzyme components are specifically selected to convert the biomass into sugar components from cellulose rather than reducing the molecular weight while maintaining the cellulose polymer character. It is important to note that US10724060 contacts oxidizing substances and enzymatic substances in aqueous medium prior to a subsequent process step for the addition of ionic liquids.

[0073] WO2016087186A1 and US8445704 describe use of ionic liquids as a processing medium for chemical modification and transformation of polysaccharides however there is no use of hydrogen peroxide / ozone, short wavelength radiation, photocatalysis and / or enzymes to address colors and impurities or to address the molecular weight of the cellulose.

[0074] US11168196 describes an approach to facilitate separation of blended cellulose / polyester waste however there is no provision for actively addressing colors, impurities, and / or molecular weight within the ionic liquid used to dissolve the cellulose component.

[0075] The adaptation of the conditions according to step (a2) can be carried out in different ways, for example by changing the solvent composition, by adding said active substances (alone or in a carrier solvent), by activating said active substances, by changing the temperature, the pH or by changing the pressure, or by introducing activation energy for example by irradiation, or a combination of such adaptations.

[0076] The term active substance in the context of (a2) includes substances which are suitable and adapted to fulfil the function to degrade non-cellulose material initially contained in the recycling cellulose material, and examples thereof are given further below.

[0077] The recycling cellulose material is preferably selected from at least one of cellulose containing streams such as waste, recycling yarns, recycling fabrics, recycling tissue, recycling clothing.

[0078] The non-cellulose material is typically selected from at least one of non-cellulosic material, including non-cellulosic fibres (e.g. PET, PA, elastane, PE, etc. or mixtures thereof), dyestuffs, fatty and other organic impurities, including oils, waxes and detergent residues, inorganic substances such as sand or clay, water soluble and water insoluble pigments. After step (a) and before or after step (b) there can be and preferably there is a step (c) of separation of non-dissolved or non-dissolvable impurities due to the dissolution of the recycling cellulose material or of absorbents, wherein preferably this step includes at least one of filtration, decanting, centrifugation, sieving.

[0079] The ionic liquid solution comprises a protic liquid, preferably water.

[0080] The active substance is preferably selected from the group of absorbents, cleaving agents, including biological cleaving agents, physical cleaving agents and chemical cleaving agents, wherein preferably absorbents are selected from the group of substances adsorbing at least one of dyestuffs, fatty impurities and other organic impurities, and wherein preferably cleaving agents are selected from the group of direct cleaving agents or activatable cleaving agents, preferably activated by irradiation of electromagnetic irradiation, wherein the cleaving agents can be selected from the group of enzymatic systems including proteases, oxidoreductases, amylases, laccases and lipases, ozone, peroxides, photocatalysts, and a combination thereof. In the examples given further below for the active substance hydrogen peroxide is used. However, this is just one possibility and the above-mentioned substances can fulfil the function of the active substance in a complementary and / or alternative way to this example with hydrogen peroxide. Preferably the active substance is a substance with acts as an oxidizer and has a bleaching effect.

[0081] Preferably, the ionic liquid from the beginning comprises or is supplemented after step (a2) or after (c), if present, with a system to reduce the molecular weight of the cellulose polymer, preferably selected from the group of enzymatic systems including cellulases or hemicellulases or cellulose oxidases, in particular endoglucanases, exoglucanases or cleaving agents activated by irradiation of electromagnetic irradiation, or strong bases, or a combination thereof.

[0082] In step (a2) the temperature is preferably increased to a range of 40-120°C, and preferably maintained at this temperature for a timespan in the range of 0.5-24 hours.

[0083] After step (a2) or after step (c) the cellulose yarn can directly be spun from the cellulose dissolved in the ionic liquid.

[0084] Said molten ionic liquid further comprises a protic solvent or a mixture of several protic solvents, wherein, in the case where the protic solvent is solely water, the cellulose dissolved in the molten ionic liquid, during or downstream of step (c), are precipitated in a coagulation medium, the coagulation medium comprising a solvent which does not dissolve the cellulose and is miscible with the molten ionic liquid, wherein preferably the molten ionic liquid is comprising a cation that is formed from compounds which contain at least one five- to six membered heterocyclic ring and a protic solvent, and the process involves precipitating dissolved cellulose in the form of carbohydrates in a coagulation medium, comprising a solvent which does not dissolve the cellulose and is miscible with the molten ionic liquid, wherein said protic solvent is selected from the group consisting of

[0085] 1) water as the sole protic solvent which is present in said solution system in an amount of less than 5 wt. %,

[0086] 2) at least 0.1 wt. % based on said solution system of at least one protic solvent selected from the group consisting of alcohols such as methanol, ethanol, 1 -propanol, 2-propanol 1- butanol, amylalcohol and linear and branched alcohols and higher linear and branched alcohols; and

[0087] 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, amylalcohol and linear and branched alcohols and higher linear and branched alcohols.

[0088] Suitable systems acting as ionic liquids are for example those, which are described in US8163215 or in US8841441 or as in WO-A-03029329, the disclosure of which is included into this specification as concerns the ionic liquid systems.

[0089] Ionic liquids in the context of the present invention are preferably

[0090] (A) salts of the general formula (I):

[0091] [A]+n[Y]n- (I) in which n represents 1 , 2, 3 or 4, [A]+represents a quaternary ammonium cation, an oxonium cation, a sulfonium cation or a phosphonium cation and [Y]n" represents a mono-, di-, tri- or tetravalent anion; or they are (B) mixed salts of the general formulae (II)

[0092] [A1]+[A2]+[Y]n“ (Ila), wherein n=2;

[0093] [A1]+[A2][A3]+[y]n“ (Hb), wherein n=3; or

[0094] [A1]+[A2]+[A3]+[A4]+[Y]n- (He), wherein n=4; and wherein [A1]+, [A2]+, [A3]+and [A4]+independently of one another are chosen from the groups mentioned for [A]+and [Y]n" has the meaning mentioned under (A). Possible is e.g. the use of 1-ethyl-3-methylimidazolium chloride. This is also what is used in the examples, but this is just one possibility and the ionic liquid substances mentioned in this general section can act as such equally in a complementary (ionic liquid mixture) and / or alternative way to this example with 1-ethyl-3-methylimidazolium chloride. In particular systems based on methylimidazolium, in particular based on 1-ethyl-3-methylimidazolium, clearly fulfil the same function, so 1-ethyl-3-methylimidazolium with different anions such as fluoride, fatty acid anions (e.g. acetate), or dicyanamide, (C2Hs)(CH3)C3H3N+2 N(CN)_2, and also systems based on 1-butyl-2,3-dimethylimidazolium or 1-butyl-3,5-dimethylpyridinium, 1-butyl-3-methylimidazolium, such as 1-butyl-3,5-dimethylpyridinium bromide, 1-butyl-3- methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide or combinations thereof.

[0095] Compounds which are suitable for forming the cation [A]+ of ionic liquids are known e.g. from DE 102 02 838 A1. Such compounds can thus contain oxygen, phosphorus, sulfur or, in particular, nitrogen atoms, for example at least one nitrogen atom, preferably 1 to 10 nitrogen atoms, particularly preferably 1 to 5, very particularly preferably 1 to 3 and in particular 1 to 2 nitrogen atoms. They can optionally also contain further hetero atoms, such as oxygen, sulfur or phosphorus atoms. The nitrogen atom is a suitable carrier of the positive charge in the cation of the ionic liquid, from which a proton or an alkyl radical can then transfer to the anion in equilibrium in order to generate an electrically neutral molecule. The system of the ionic liquid may also be one based systems containing a cationic 1 ,5,7- triazabicyclo[4.4.0]dec-5-enium [TBDH]+ moiety and an anion selected from the group according to Formula a), Formula b) and Formula c), as for example described in WO2018 / 138416, which is also included into this specification as concerns ionic liquid systems.

[0096] According to yet another preferred embodiment, said molten ionic liquid comprises a protic solvent or a mixture thereof, and the method involves, during or downstream of step (c), precipitating the cellulose in a coagulation medium, a protic coagulation agent or a mixture of protic coagulation agents being present in the coagulation medium, and wherein the surface tension o of the protic coagulation agent or the mixture of protic coagulation agents is 99% to 30% of the surface tension o of water, each surface tension being measured in accordance with ASTM D 1590-60 at a temperature of 50° C, wherein preferably the protic coagulation agent is selected from water, water in a mixture with the ionic liquid, 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 wherein further preferably the coagulation medium does not contain more than 5% of carboxylic acid.

[0097] Preferably step (a) at least partly takes place under an oxidative atmosphere.

[0098] According to a first preferred embodiment, the oxidative atmosphere during step (a) is an oxygen containing atmosphere, more preferably air, preferably under atmospheric conditions.

[0099] According to yet another preferred embodiment, the oxidative atmosphere at a humidity of less than 30 g / m3, more preferably at a humidity of less than 15 g / m3, most preferably at a humidity of zero or less than 10 or less than 5 g / m3.

[0100] Preferably, the exposure to the oxidative atmosphere in step (a) takes place during a time span of at least 10 minutes, preferably at least 30 minutes, or in the range of 40-300 minutes, or in the range of 60-120 minutes.

[0101] Typically, the exposure takes place under ambient temperature conditions.

[0102] Oxidizing as chemical reaction is a function of temperature and time, kinetics is controlled also by temperature. So, the given conditions of temperature and time also equally extend to situations where an equivalent oxidizing effect is achieved for example at a lower temperature over a longer time span or at a higher temperature over a shorter time span. In fact, it was surprisingly found, contrary to expectations, that there is a beneficial effect associated with keeping the mixture of cellulose in the ionic liquid under an oxidative atmosphere leading to first break down of the cellulose. Unexpectedly neither the ionic liquid nor the cellulose nor the subsequent treatment with the active agent is negatively influenced by subjecting the ionic liquid with the cellulose to the oxidative atmosphere. The contrary is the case, the oxidative surrounding in the mixing process and dissolution process or after the dissolution process starts the oxidative degradation of the cellulose and prepares the cellulose even better for subsequent treatment with the active agent. It was thought that exposure to oxidants would be a problem for the stability of the ionic liquid, which was found not to be true.

[0103] This exposure to oxidative atmosphere can be carried out as just exposing the corresponding container with the liquid on the surface to the oxidative atmosphere, however it can also be strengthened by active stirring of the solution under this atmosphere, and even more can be forced by bubbling oxidative atmosphere through the solution to speed up the process. 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.

[0104] In the context of this disclosure, the expressions “atmospheric pressure” and “ambient temperature” refer to the pressure and temperature conditions to that a reactor is normally exposed to, i.e. typically atmospheric pressure stands for pressures in the range of 0.8 to 1.1 bar (absolute pressure) and typically ambient temperature refers to temperatures in the range of 10 to 60° C, more typically 20 to 35°C. The gas mixture used as input for the process is preferably ambient atmospheric air, i.e. air at ambient atmospheric pressure and at ambient atmospheric temperature, which normally implies a CO2 concentration in the range of 0.03-0.06% by volume. However, also air with lower or higher CO2 concentration can be used as input for the process, e.g. with a concentration of 0.1 -0.5% by volume, so generally speaking, preferably the input CO2 concentration of the input gas mixture is in the range of 0.01-0.5% by volume. An oxidative atmosphere is a gas which contains an oxidative species, preferably oxygen. Typically, that oxidative species is present in the oxidative atmosphere in a percentage of at least 10%, preferably at least 15% or in the range of 15-99%. As mentioned, preferably the oxidative atmosphere is air, i.e. a mixture of 20-25% oxygen, supplemented by nitrogen and less than 1% of other gases. This composition, when talking about air as oxidative atmosphere, is present at least at the beginning of the exposure of the ionic liquid solution to that oxidative atmosphere, during the process due to consumption of the oxygen the oxygen content in the oxidative atmosphere may decrease.

[0105] The feedstock cellulose can be recycling cellulose material in particular selected from at least one of cellulose waste, recycling yarns, recycling fabrics, recycling tissue, recycling clothing, other cellulose streams including cellulose containing waste streams.

[0106] Generally speaking, said molten ionic liquid comprises a protic solvent or a mixture of several protic solvents, wherein the protic solvent is solely water and is present in the solution system in an amount of less than 5 wt. %, the cellulose dissolved in the molten ionic liquid are, during or downstream of step (c), precipitated in a coagulation medium, the coagulation medium comprising a solvent which does not dissolve the cellulose and is miscible with the molten ionic liquid, wherein preferably the molten ionic liquid is comprising a cation that is formed from compounds which contain at least one five-to six membered heterocyclic rings, preferably based on at least one of 1-ethyl-3-methylimidazolium, 1-butyl- 2,3-dimethylimidazolium, 1-butyl-3,5-dimethylpyridinium, 1-butyl-3-methylimidazolium with at least one counter ion selected from at least one of chloride, acetate, fluoride, dicyanamide or a fatty acid anion, and a protic solvent, and the process involves precipitating dissolved cellulose in the form of carbohydrates in a coagulation medium, comprising a solvent which does not dissolve the cellulose and is miscible with the molten ionic liquid.

[0107] Said molten ionic liquid preferably comprises a protic solvent or a mixture thereof, and the method, during or downstream of step (c), involves precipitating the cellulose in a coagulation medium, a protic coagulation agent or a mixture of protic coagulation agents being present in the coagulation medium, and wherein the surface tension o of the protic coagulation agent or the mixture of protic coagulation agents is 99% to 30% of the surface tension o of water, each surface tension being measured in accordance with ASTM D 1590- 60 at a temperature of 50° C.

[0108] According to a further aspect of the present invention it relates to cellulose with a tenacity of more than 30 cN / tex, preferably of more than 40 cN / tex, with an elongation of more than 5%, preferably of more than 10%, and with a low degree of fibrillation, preferably graded less than 3, preferably 1. The degree of fibrillation is is evaluated by fixing single filaments (2.5 cm length) to a frame which is then placed into a cylinder with 20 ml of distilled water and 9 g of zirconia spheres (0.75 - 1 mm). The cylinder containing the filaments, water and zirconia spheres are agitated in a Labomat at 30°C for 3 hours and a rate of 50 rpm. 16 filament pieces are tested per sample. After the defined time the yarn material assessed under the microscope and the number of fibrils standing out of the yarn filaments are counted. Fibrillation was classified according to the following scale 1 (0-5 fibrils), 2 (6-10 fibrils), 3 (11-20 fibrils), 4 (21-40 fibrils), 5 (> 40 fibrils).

[0109] Tenacity, and elongation were measured according to the BISFA standard for testing methods for viscose, cupro, acetate, triacetate and lyocell filament yarns (BISFA (2007). Testing methods for viscose, cupro, acetate, triacetate and lyocell filament yarns (2007 Edition). The International Bureau for the Standardisation of Man-Made Fibres.)

[0110] According to yet another aspect of the present invention, it relates to the use of cellulose yarn as given above for the production of textiles, in particular of clothing.

[0111] The produced cellulose yarn may be used directly in a variety of textile processes including texturizing; twisting; covered yarns (core spun yarns); knitting; weaving; seamless; circular knitting with other yarns (such as cotton, nylon, polyester, polypropylene, cellulosics, wool, silk, polyurethane); warp knitting; beaming process; staple fibers; nonwovens. The produced cellulose yarn may be used directly in a variety of textile forms including Denim; Hosiery; Intimate; Sportswear; Fashion; Shoes; Sewing threads; Upholstery; Home textiles; Industrial textiles.

[0112] Further embodiments of the invention are laid down in the dependent claims.

[0113] BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

[0115] Fig. 1 shows schematic process steps for processing of recycled cellulose into regenerated cellulose fibers compared to a process possible with the invention;

[0116] Fig. 2 shows the process scheme in particular including the step with a storage vessel for equilibration of the solution of cellulose material in ionic liquid with water.

[0117] DESCRIPTION OF PREFERRED EMBODIMENTS

[0118] Fig. 1 shows in the upper row a schematic process for conventional pre-processing of recycled cellulose materials to remove colors and impurities followed by dissolution in ionic liquid and subsequent fiber spinning. In contrast the present invention as illustrated in the lower row allows direct dissolution of the recycled cellulose in ionic liquid if need be under an oxidative atmosphere and if need be subsequent active agent addition enabling colors and impurities to be processed directly in the ionic liquid dope with subsequent fiber spinning. The present invention enables reduced process complexity and reductions in energy and water use compared to conventional processes.

[0119] There is a certain unclarity in the filed regarding the definition of direct dissolution cellulose spinning processes, whether the definition of Lyocell constrains to the use of the solvent N- methylmorpholine n-oxide (NMMO). Through the text here we adopt the Lyocell fiber definition according to the Ell regulation No 1007 / 2011 of 27th of September where the names of textile fibers are defined. There, Lyocell fibers are defined as a regenerated cellulose fibre obtained by dissolution, and an organic solvent (mixture of organic chemicals and water) spinning process without formation of derivatives, without limitation to NMMO. The method for the production of a regenerated fiber using a Lyocell type of process are known for a person skilled in the art and can be found in numerous publications such as recently WO2022153170A1.

[0120] Briefly the fiber spinning process normally contains the steps: a) Cutting the cellulose pulp into pieces < 4 mm (may be carried out in a high-speed mixer, ball mill, shredder and the like) b) Preparation of a pre-mix: by putting in contact the cut cellulose pulp (< 4 mm) with an organic solvent, potentially adding H2O. (Equipment selected from a group consisting of sigma mixer, reactor kneader, wiped film evaporator and the like) c) Homogenizing the pre-mix: The pre-mixing is homogenized through mechanical agitation mixing the dope for a time-period between 0 to 6 hours until a homogenous solution has been obtained. d) Removing the excess water until the final H2O content is significantly < 5%. (Equipment selected from a group consisting of sigma mixer, reactor kneader, wiped film evaporator and the like) e) The dope solution is extruded through suitable nozzles at a range of temperatures 65°C ± 30°C depending on the viscosity of the solution. The extruded solution is subjected to an air gap spinning and regenerated into the spinning bath. The spinning bath comprises of solvent in a concentration ranging between 5 to 30 wt% in water. The fibers are drawn off, optionally cut into staple fibers, washed, bleached, finished, dried.

[0121] Fig. 2 shows an overall view of the process which is proposed here. The key steps are defined in the claim, this figure illustrates all steps which can be carried out.

[0122] The process starts with a step of pulp preparation (A) followed by transferring the pulp into an ionic liquid in step (B). This is followed by the actual dissolution process, which is termed mash preparation (C) followed by dissolution in the dissolution unit (D). The resulting cellulose dissolved in ionic liquid with water is then transferred and filtered in step (E) and introduced into a storage vessel (F). After equilibration in the buffer tank (F) for an appropriate amount of time at the appropriate temperature, the resulting viscous material is introduced into the spinning block and airgap in unit (G) and ejected into the spin bath (H). The fibers are subjected to washing and drying in unit (I), this can be followed by a spin finish application step (J) and texturizing (K).

[0123] The ionic liquid which is present in the spin bath and which results from the washing step can be recycled in the IL recovery unit (L) and can be transferred to the IL supply unit (M) for recycling and reusing it in unit (B).

[0124] In the following these individual steps / units shall be detailed somewhat more.

[0125] (A): in this step the cellulose feedstock starting material is prepared. This can be recycled cellulose material (for example recycled textiles), cellulose from waste streams (agricultural or food) or original cellulose material, it can be from bacterial origin or algal origin or from plant (wood) origin. Typically, the material is cut and shredded to the appropriate size to form particles which are suitable for dissolution. The particle size should be less than 3 mm (D50), preferably less than 1 mm. Typically the starting material has a degree of polymerization in the range of 500-1500, preferably in the range of 600-800.

[0126] (B): in this step the material resulting from step (A) is transferred using pumps or pneumatic systems. If needed, in the same unit the ionic liquid can be warmed up with a heat exchanger to prepare for the dissolution.

[0127] (C): in this step the aim is to produce a homogeneous mixture of the cellulose powder with the ionic liquid, which is termed mash. Normally in this step dissolution is not substantially taking place yet, which can take place under an inert atmosphere or under oxidative conditions specifically to tune the degree of polymerization of the cellulose material. The mixing typically takes a few minutes up to hours. The incoming ionic liquid is tuned to have a water content in the range of less than 5 wt. %, the cellulose content is typically in the range of 5-25%, depending on the viscosity / degree of polymerization.

[0128] (D): in this step at elevated temperature the actual dissolution is carried out, the device used can be an extruder, a kneader or another type of mixers and evaporator systems such as falling film and wiped blade configurations. Preferably the temperature is in the range of less than 150°C, typically around 100°C, and the dissolution can be carried out while heating under negative pressure to remove evaporated water.

[0129] (E): in this step the dissolved cellulose material in the ionic liquid and water is transferred to the storage vessel. In particular if recycled feedstock is used, filtering can be important in this step, filters can be of the grid type. Optionally filtration can alternatively or additionally be employed after step F and before step G.

[0130] (F): in this step the material is prepared for the actual spinning process. To this end the solution is equilibrated, in this case in a storage vessel. The temperature during the equilibration, which typically takes place over 6-10 hours, is kept (under active heating) in the range of 80-90°C. The material is not stirred actively during that time and contact with oxidative air is avoided.

[0131] (G): in this step the cellulose solution is extruded through a nozzle plate to create the filaments to be drawn in the air gap, the process is driven by a spinning pump.

[0132] (H): in this step the resulting filaments are introduced into a spin bath, which is typically water containing the same ionic liquid as used for dissolution. The spin bath can be a static bath, but it can also be an accelerated bath.

[0133] (I): in this step the goal is to remove the ionic liquid completely from the yarn, which can be carried out countercurrent and / or at elevated temperature, followed by drying.

[0134] (J): in this step an optional spin finish is possible, for example application of water / oil emulsions etc.

[0135] (K): in this step texturizing can be carried out, possible is the application of elevated temperature and / or pressurized air. In fact, the high tenacity and elongation fibers which can be obtained using the proposed process allow for much more texturizing than using other cellulose spinning processes.

[0136] (L): in this step the ionic liquid is recovered, i.e. excess water is removed and also any residuals, in particular in case of using recycled feedstock. Possible is the use of evaporation, filtering, sedimentation, centrifugation, osmotic methods and combinations thereof.

[0137] (M): in this unit the recovered ionic liquid is supplied in a closed circle to the dissolution again. Due to the proposed method exceptionally high performance yarns can be obtained, they have a tenacity of more than 30 cN / tex in dry state, and an elongation of more than 5%.

[0138] What is observed is that the proposed process allows to maintain a high degree of polymerization throughout the whole process so there is no substantial decrease in the length of the cellulose chains. This allows to robustly reach the high tenacity and elongation values, and is in contrast to the environmentally unfriendly and unproductive viscose process, where during the production the degree of polymerization inherently undergoes significant reduction, leading to less beneficial fiber properties.

[0139] The resulting properties compared with other types of fibers are summarized in Table 2:

[0140] Tenacity, and elongation were measured according to the BISFA standard for testing methods for viscose, cupro, acetate, triacetate and lyocell filament yarns (2007 edition) Fibrillation is measured as described above.

[0141] Experimental example 1

[0142] A cellulose dope mixture was prepared by suspending cellulose powder (cut to <4mm) in a mixture of ionic liquid (1-Ethyl-3-methylimidazolium acetate) and water as protic solvent. The mixture was subsequently heated and blended in a mechanical kneader at 90°C under vacuum to achieve an output homogeneous dope mixture batch of 20 kg composed of 10% w / w cellulose, >85% ionic liquid and <5% water.

[0143] In one set of experiments (1A) the as-prepared dope mixtures were directly pumped at a rate of 0.5 kg / h to a spinning nozzle consisting of 150 holes of 0.1mm diameter, with each hole exit maintained at 20mm air-gap height above a coagulating bath consisting of water. The coagulated filaments were drawn from the bath and subsequently dried and wound onto bobbins for subsequent characterization.

[0144] In a separate set of experiments (1 B) the as-prepared dope mixture was fed to a heated storage vessel maintained at 90°C. An inert gas (nitrogen) was issued to the head space above the dope liquid to avoid oxidative conditions. The dope mixture was subsequently maintained in the storage vessel essentially without stirring for a period of 10 hours (equilibration time). After the equilibration time period was completed the dope mixture was pumped to the spinning nozzle and associated downstream systems at the same rate of 1 kg / h and otherwise identical conditions to experiment 1A.

[0145] The fiber spinning experiments were observed for spinning stability, that is the ability to achieve successful spinning of continuous filaments and collect on bobbins as a single length of contiguous multifilament yarn. A stable production process is achieved when filaments can be produced stably (spinning without interruption or filament breakage) over a prolonged period of time of at least 10 minutes. In filament production the period of stable production time can be expressed as a length of produced filament. For example, a 15km length of 150 dtex multifilament yarn produced in the 0.5kg / h spinning rate above would require >27 minutes of stable continuous production. For meaningful industrial production it is essential that the spinning process is capable of maintaining stable continuous production conditions and product properties over long periods of time, i.e. over more than 3 hours or more than 8 hours at least. For purposes of the example, stable production was assessed at achieving >15km continuous production.

[0146] The above experiments yielded the following observations:

[0147] The above experiments illustrate the industrial process stability benefit provided by maintaining the dope mixture for a period of equilibration in a vessel essentially without stirring and preferably without contact with air.

Claims

CLAIMS1. Method for the production of cellulose yarns from a feedstock cellulose material, wherein the method comprises the following steps:(a) mixing and dissolution of the feedstock cellulose material in a solution containing at least a molten ionic liquid, wherein the solution containing ionic liquid with dissolved cellulose material comprises a protic liquid in an amount of less than 5 wt. % and wherein at the end of dissolution the solution containing ionic liquid with dissolved cellulose material and a protic liquid is at a temperature in the range of 50-120°C;(b) maintaining the solution containing ionic liquid with dissolved cellulose material and a protic liquid at a temperature in the range of 40-95°C for a time span in the range of 3-18 hours essentially without stirring and preferably essentially without contact with air;(c) extruding the solution containing ionic liquid with dissolved cellulose material and a protic liquid through at least one spinning nozzle, wherein the solution containing ionic liquid with dissolved cellulose material and a protic liquid during extrusion through at least one spinning nozzle comprises a protic liquid in an amount of less than 5 wt. %.

2. Method according to claim 1 , wherein in step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is maintained at a temperature in the range of 60-90°C, preferably in the range of 70-90°C, and / or wherein in step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is maintained for a time span in the range of 5-15 hours, preferably in the range of 7-10 hours.

3. Method according to any of the preceding claims, wherein during step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is heated to maintain, during step (b), a constant temperature around a fixed value, preferably a fixed value in the range of 75-90°C, with a deviation of less than 10°C, preferably of less than 5°C above and below that fixed value.

4. Method according to any of the preceding claims, wherein the zero shear viscosity of the solution containing ionic liquid with dissolved cellulose material and a protic liquid is in the range of 1 ,000-50,000 Pa.s at 50°C, preferably in the range of 2,000-10,000 Pa.s at 50°C during step (b) and / or during step (c).

5. Method according to any of the preceding claims, wherein the cellulose content of the solution containing ionic liquid with dissolved cellulose material and a protic liquid during step (b) and / or step (c) is in the range of 2-20% by weight, preferably in the range of 5-18% by weight.

6. Method according to any of the preceding claims, wherein the protic liquid of the solution containing ionic liquid with dissolved cellulose material and a protic liquid during step (b) and / or step (c) is selected to be, preferably solely, water and the content thereof is in the range of 1.5-4.5% by weight, preferably in the range of 2-4% by weight.

7. Method according to any of the preceding claims, wherein for step (b) the solution containing ionic liquid with dissolved cellulose material and a protic liquid is maintained in a storage vessel or a section of a storage tube, and wherein at least for transferring the solution containing ionic liquid with dissolved cellulose material and a protic liquid into said storage vessel or section of a storage tube, a pump is used, if need be assisted by applying a negative headspace pressure, wherein preferably in the headspace above said solution a pressure in the range of 5-200 mbar, preferably in the range of 10-50 mbar is established.

8. Method according to any of the preceding claims, wherein for transferring the solution containing ionic liquid with dissolved cellulose material and a protic liquid after step (b) for step (c) to the spinning beam a pump is used, if need be assisted by an inert gas in the headspace, preferably nitrogen gas, is used, preferably in the headspace above the solution containing ionic liquid with dissolved cellulose material and a protic liquid, preferably at an overpressure, in particular in the range of 1.5-4 bars, preferably in the range of 2-3.5 bars, and / or wherein for step (c) the temperature of the solution containing ionic liquid with dissolved cellulose material and a protic liquid is reduced to a value in the range of 70- 90°C, preferably in the range of 75-85°C.

9. Method according to any of the preceding claims, wherein step (a) is incorporating and / or followed by the following steps(a1) adding and dissolving and / or dispersing at least one active substance or a precursor thereof in said solution;(a2) adapting the conditions such that said active substances dissolved or dispersed in the solution containing molten ionic liquid or generated in situ in the solutioncontaining molten ionic liquid act to degrade non-cellulose material initially contained in the recycling cellulose material and contained in the solution containing molten ionic liquid due to the dissolution of the recycling cellulose material,10. Method according to any of the preceding claims, wherein at least step (a) at least partly takes place under an oxidative atmosphere, wherein preferably the oxidative atmosphere during step (a) is an oxygen containing atmosphere, more preferably air, preferably under atmospheric conditions, more preferably at a humidity of less than 30 g / m3, more preferably at a humidity of less than 15 g / m3, most preferably at a humidity of zero or less than 10 or less than 5 g / m3, wherein preferably the exposure to the oxidative atmosphere in step (a) takes place during a time span of at least 10 minutes, preferably at least 30 minutes, or in the range of 40-300 minutes, or in the range of 60-120 minutes.

11. Method according to any of the preceding claims, wherein the feedstock cellulose is recycling cellulose material in particular selected from at least one of cellulose waste, recycling yarns, recycling fabrics, recycling tissue, recycling clothing, other cellulose streams including cellulose containing waste streams.

12. Method according to any of the preceding claims, wherein said molten ionic liquid comprises a protic solvent or a mixture of several protic solvents, wherein the protic solvent is solely water and is present in the solution system in an amount of less than 5 wt. %, the cellulose dissolved in the molten ionic liquid are, during or downstream of step (c), precipitated in a coagulation medium, the coagulation medium comprising a solvent which does not dissolve the cellulose and is miscible with the molten ionic liquid, wherein preferably the molten ionic liquid is comprising a cation that is formed from compounds which contain at least one five-to six membered heterocyclic rings, preferably based on at least one of 1-ethyl-3-methylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-butyl-3,5- dimethylpyridinium, 1-butyl-3-methylimidazolium with at least one counter ion selected from at least one of chloride, acetate, fluoride, dicyanamide or a fatty acid anion, and a protic solvent, and the process involves precipitating dissolved cellulose in the form of carbohydrates in a coagulation medium, comprising a solvent which does not dissolve the cellulose and is miscible with the molten ionic liquid, and / or wherein said molten ionic liquid comprises a protic solvent or a mixture thereof, and the method, during or downstream of step (c), involves precipitating the cellulose in a coagulation medium, a protic coagulation agent or a mixture of protic coagulation agents being present in the coagulation medium, and wherein the surfacetension o of the protic coagulation agent or the mixture of protic coagulation agents is 99% to 30% of the surface tension o of water, each surface tension being measured in accordance with ASTM D 1590-60 at a temperature of 50° C.

13. Method according to claim 12, wherein the protic coagulation agent is selected from water, water in a mixture with the ionic liquid, 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 wherein further preferably the coagulation medium does not contain more than 5% of carboxylic acid.

14. Cellulose yarn with a tenacity of more than 30 cN / tex, preferably of more than 40 cN / tex, with an elongation of more than 5%, preferably of more than 10%, and with a low degree of fibrillation, preferably of less than 3, preferably less than 2, most at most 1 , obtained using a method according to any of the preceding claims.

15. Use of cellulose yarn according to claim 14 for the production of textiles, in particular of clothing, preferably directly in textile processes including texturizing; twisting; covered yards; knitting; weaving; seamless; circular knitting with other yarns, including cotton, nylon, polyester, polypropylene, cellulosics, wool, silk, polyurethane; warp knitting; beaming process; staple fibers; nonwovens, wherein the textiles are preferably selected from the group of Denim; Hosiery; Intimate; Sportswear; Fashion; Shoes; Sewing threads; Upholstery; Home textiles; Industrial textiles.

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