Cellulosic Textile Fibers

Abstract

According to an exemplary embodiment of the present invention, there is provided an artificial cellulosic textile fiber having a linear density of 0.8-1.8 dtex, a tensile strength / elongation of 2.0-2.9 cN / dtex, and an initial modulus of elasticity of 50-120 cN / dtex. The cellulosic textile fiber comprises a cellulosic material, at least 50 wt% of the raw material of the textile fiber is cellulose-containing waste, and at least 50 wt% of the cellulose-containing waste is textile waste.

Description

[Technical field]

[0001] The present invention relates to cellulosic textile fibers. Additionally, the present invention relates to a method for making the cellulosic textile fibers. Uses of the cellulosic textile fibers and articles comprising the cellulosic textile fibers are also disclosed. [Background technology]

[0002] Cellulose, the most abundant renewable organic material on earth, exhibits excellent properties for textile applications. The viscose process remains the most widely used technique for producing regenerated cellulose fibres and films, despite environmental challenges. There is therefore a need to develop simpler, more sustainable fibres with improved properties compared to traditional production processes.

[0003] EP 1509548 and EP 1470162 both describe the production of cellulose carbamate from high-quality cellulose solutions. Cellulose carbamate is known as an environmentally friendly alternative for the production of man-made cellulose-based fibers. WO 2021 / 038136 also describes the spinning of fibers from cellulose carbamate. However, cellulose carbamate technology has not been able to produce textile-quality fibers so far, although it has, for example, acceptable strength properties. Summary of the Invention

[0004] It is an object of the present invention to overcome at least some of the problems associated with the prior art and provide textile-quality man-made cellulosic fibers. In accordance with embodiments, it has surprisingly been found that by modifying the spin bath and the conditions under which the fibers are drawn, man-made cellulosic fibers having improved properties can be obtained. In particular, the method of the present invention allows the production of cellulosic fibers at least partially from waste materials, and yet provides fibers having sufficient strength for use in the textile industry.

[0005] The invention is defined by the features of the independent claims. Some particular embodiments are defined in the dependent claims.

[0006] According to a first aspect of the present invention, there is provided an artificial cellulose fiber having a linear density of 0.8-1.8 dtex, a tensile strength and elongation of 2.0-2.9 cN / dtex, and an initial modulus of elasticity of 50-120 cN / dtex. The artificial cellulose fiber is such that at least 50 wt% of the raw material is cellulose-containing waste, and at least 50 wt% of the cellulose-containing waste is textile waste.

[0007] According to a second aspect of the present invention, there is provided a method for producing a cellulosic textile fiber, comprising the steps of pretreating a cellulosic material comprising at least 50 wt. % cellulose-containing waste, at least 50 wt. % of the cellulose-containing waste being textile waste; cellulose carbamation to form cellulose carbamate; dissolving the cellulose carbamate in an aqueous alkaline medium to form a cellulose carbamate dope; and spinning the cellulose carbamate dope in an aqueous spinning medium to form a filament or filament tow, while drawing the filament or filament tow by at least 70% in length when the temperature of the drawing bath is 75-100°C, to obtain a cellulose carbamate fiber having a linear density of 0.8-1.8 dtex, a tensile strength and elongation of 2.0-2.9 cN / dtex, and an initial modulus of 50-120 cN / dtex.

[0008] According to a third aspect of the present invention, there is provided a cellulosic fibre obtainable according to the second aspect of the present invention.

[0009] According to a fourth aspect of the invention there is provided the use of a cellulosic textile fibre according to any of the above aspects of the invention in an article.

[0010] According to a fifth aspect of the present invention, there is provided an article comprising a cellulosic textile fiber of any of the above aspects of the present invention. [Brief description of the drawings]

[0011] [Figure 1] 1 shows tensile strength elongation strain curves for a reference material and a man-made cellulosic textile fiber according to at least some embodiments of the present invention. [Diagram 2] 1 is a light microscope photograph illustrating a fiber according to at least some embodiments of the present invention. [Diagram 3] 1 is a light microscope photograph illustrating a cross-section of a man-made cellulosic fiber according to at least some embodiments of the present invention. [Figure 4] 1 is an electron microscope photograph showing a cross section of a reference fiber sample. [Diagram 5] 1 is an electron micrograph showing a cross-section of a fiber sample according to at least some embodiments of the present invention. [Figure 6] 1A-1C are optical micrographs comparing the uniformity and brightness of fibers according to at least some embodiments of the present invention to a reference fiber. [Figure 7] 1A-1C are optical micrographs illustrating structural differences between fibers according to at least some embodiments of the present invention and reference fibers. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Man-made cellulose fibers are fibers whose structure and properties are altered during the manufacturing process. Man-made fibers are distinct from natural fibers such as silk, cotton, and wool. Man-made cellulose fibers are made of the same cellulose polymers that make up the structural fibers of cotton, hemp, flax, and wood. In man-made cellulose fibers, the cellulose is either obtained in a modified state, such as cellulose obtained from wood pulping operations, or modified to regenerate into usable cellulosic fibers.

[0013] Linear density, a measure of the mass per unit length of a fiber, is used by textile manufacturers as a measure of fineness. Linear density in decitex is the weight in grams of a 10,000 m length of fiber. Decitex is recognized as the SI unit of linear density. Linear density in dtex is measured according to ISO1973:2021.

[0014] Tensile strength is a measure of the strength of a fiber. It is usually defined as the ultimate (breaking) force of the fiber (in gram-force) divided by the linear density. Tensile strength is defined as the ratio of the ultimate (breaking) force / load to the linear density of the sample. The tensile strength of a sample can be expressed in units such as cN / dtex, grams / tex, grams / denier, or Newtons / tex. The tensile strength of a fiber (cN / dtex) is measured according to ISO5079:2020.

[0015] In textiles, the term initial modulus is used to describe the resistance of textile fibers to initial elongation and is measured using ISO5079:2020. In other words, it is a measure of the fiber's resistance to a small initial elongation. If a fiber has a high resistance to stretching, it has a high modulus. The tangent of the angle the initial curve makes with the horizontal axis is equal to the ratio of stress to strain. This ratio is called the initial modulus, but in textiles it is called the initial Young's modulus. The initial modulus of a textile fiber depends on the chemical structure, the degree of crystallinity, the orientation of the fiber, etc. The initial modulus is tan α = stress / strain.

[0016] Breaking elongation is the elongation of the fiber caused by the breaking force. Breaking elongation (%) = breaking elongation x 100 / original length of the test piece. Measured using ISO5079:2020.

[0017] Nitrogen content in cellulosic textile fibers or in cellulose carbamates means the amount of nitrogen bound to the cellulose as carbamate groups, expressed as a percentage by weight of the total weight of the fiber or cellulose carbamate (depending on the time of measurement), measured according to SFS 5505:1988.

[0018] In the present invention, cellulosic fibers refer to fibers in the form of staple fibers, short cut fibers, flock, filament yarns, and filament tows. In the present invention, cellulosic textile fibers also refer to fibers used in nonwoven applications. The term filaments in this specification should be understood to include filament tows.

[0019] The feedstock can be different types of cellulose-rich textile waste, such as post-consumer waste, pre-consumer waste, industrial textile waste or side streams from textile manufacturing. The textile waste can be collected and sorted. The terms recycled waste material and waste material can also be used interchangeably.

[0020] In this specification, when weight percent (wt%) is used, it means weight percent within the relevant material, unless otherwise indicated.

[0021] Unless otherwise specified, the term heat bath shall mean a bath having a temperature in the range of 75 degrees Celsius to 100 degrees Celsius.

[0022] As mentioned above, embodiments of the present invention relate to man-made cellulosic textile fibers, and in particular to wet-spun man-made cellulosic textile fibers.

[0023] In an embodiment, the man-made cellulosic textile fibers have a linear density of 0.8-1.8 dtex, a tensile strength of 2.0-2.9 cN / dtex, an initial modulus of 50-120 cN / dtex, and include cellulosic materials. Fibers with dtex at the lower end of the range, such as 0.8-1.3, are suitable for providing lightweight textile products, for example, from fibers with titers typically of about 1.5 or less. Cotton fibers typically have tensile strengths at the upper and higher ends of this range, while conventional wet-spun man-made cellulosic fibers typically have tensile strengths at the lower end of this range. The cN / dtex values ​​of man-made cellulosic textile fibers according to the embodiment are measured in the dry, i.e. conditioned, state. Values ​​in the range of 50 to 120 cN / dtex are higher than those of conventional artificial viscose, which typically has a modulus measured in the dry state, for example in the range of 20 to 40 cN / dtex.

[0024] The cellulosic textile fibers comprise a cellulosic material, in which at least 50 wt.% of the raw material of the textile fibers is cellulose-containing waste, and at least 50 wt.% of the cellulose-containing waste is textile waste. According to an embodiment, the raw material of the textile fibers is 100% textile waste, i.e. only textile waste is used as raw material.

[0025] In an embodiment, the fibers have a content of p-terephthalate and / or p-terephthalic acid, and / or unhydrolyzed or partially unhydrolyzed polyester, in particular polyethylene terephthalate, of 0.00005-0.5 wt %, as determined by gas chromatography-mass spectrometry (GC-MS), as described in more detail below in the examples. The amount may be, for example, less than 0.2 wt %, preferably less than 0.1 wt %. The presence of p-terephthalate and / or p-terephthalic acid, and / or unhydrolyzed or partially unhydrolyzed polyester is an indication that textile waste was used as a raw material in the production of cellulose carbamate.

[0026] The cellulosic materials may include virgin cellulose and / or recycled cellulose from sources such as jute, hemp, kenaf, cotton, bagasse, etc. Man-made cellulosic fibers according to embodiments of the invention have good resistance to abrasion, i.e., good strength properties. The fibers have an initial modulus similar to cotton, thereby providing the fibers of the embodiments described herein with good strength properties for threads, yarns and fabrics made from a combination of virgin cellulose, e.g., cotton, entangled with the fibers of the invention.

[0027] The cellulosic textile fiber of the present invention is such that at least 50 wt% of the raw material of the textile fiber is cellulose-containing waste, and at least 50 wt% of the cellulose-containing waste is textile waste. Thus, the fiber of the present invention and the method for its production make it possible to produce a textile fiber containing recycled materials, and still have properties that allow it to be used in the textile industry, such as in weaving.

[0028] According to an embodiment of the present technology, a cotton-like artificial fiber is provided. The elongation of the fiber of the present invention can be adjusted, for example, by drawing and by modifying the carbamate content so that the fiber generally exhibits an elongation in the range of about 5-20%, preferably about 7-19%. Thus, the present technology can provide a fiber having elongation properties similar to cotton. According to an embodiment of the present technology, for example, the above-mentioned type of fiber is provided, which is flexible enough to be easily used in the yarn manufacturing process.

[0029] Specialty rayon fibers such as Modal have improved mechanical wettability properties, however the cellulosic textile fibers of the present invention are more economically viable and more similar to cotton while still possessing the above improved properties.

[0030] In one embodiment, the cellulosic textile fibers comprise 90 wt% or more, in particular 95 wt% or more, cellulose by dry weight. Small amounts of non-cellulosic components such as plastics, nylon, polyethylene, polypropylene, elastane, and possibly nitrogen-containing impurities such as biuret may also be present. In addition, spin finishes are used to improve processability, for example in carding and / or yarn manufacturing. Optionally, other additives can be incorporated into the cellulosic textile fibers. Optional chemicals can be used to modify processability and / or to modify physical properties such as tensile strength, modulus or stretchability of the final product. Optional chemicals may act as tracers. Processing aids, surfactants, lubricants, wetting agents, stability, color and brightness modifiers, titanium dioxide, for example anatase or rutile titanium dioxide, dyes, pigments, flame retardants, fillers, antistatic agents and aids to reduce fiber friction may also be present in the cellulosic textile fibers.

[0031] In a further embodiment, the cellulosic material comprises recycled waste material, and suitably at least 25 wt%, preferably at least 50 wt%, of the cellulose of said cellulosic material is formed by recycled textile waste.As mentioned above, at least 50 wt% of the raw material of the textile fiber is cellulose-containing waste, and at least 50 wt% of the cellulose-containing waste is textile waste.It is also possible to use at least 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 wt% of the cellulose-containing waste as raw material.Of this cellulose-containing waste, at least 50 wt% is textile waste, and the textile waste can be at least 55, 60, 65, 70, 75, 80, 85, 90, 95 or 100 wt% of the cellulose-containing waste.As will be described below, the cellulose-containing waste can also comprise, for example, paper or cardboard waste.

[0032] The man-made fibers obtained by the process of the present invention can be combined with cotton fibers and intertwined with the cotton fibers to provide threads or yarns with interesting properties. The cotton fibers can be virgin cotton fibers or recycled cotton fibers, such as mechanically recycled cotton fibers, or blends containing virgin cotton fibers and mechanically recycled cotton fibers can be used with the fibers of the present invention. Thus, man-made fibers, such as, optionally, made from recycled cotton, can be used to replace at least a portion of the virgin cotton in threads, yarns and textile products, as well as other articles containing cellulosic fibers.

[0033] In a further embodiment, the cellulosic textile fibers are cellulose carbamate fibers. In one embodiment, the cellulosic textile fibers have an elongation of 7-19% of the fiber length before break and a nitrogen content of 0.10-1.2 wt%, preferably 0.15-1.0 wt%, in particular 0.3-0.9 wt%, based on the dry weight of the fiber. In one embodiment, the cellulosic textile fibers have a wet strength of at least 0.9 cN / dtex and a relative wet strength of 40-80%, preferably 45-80% (wet tensile strength / dry tensile strength).

[0034] In a particular embodiment, the cellulosic textile fibers exhibit a linear density of 1.1 to 1.5 dtex, preferably 1.2 to 1.4 dtex. The cellulosic textile fibers may also have a tensile strength and elongation of 2.1 to 2.8 cN / dtex, preferably 2.4 to 2.7 cN / dtex. According to another embodiment, the cellulosic textile fibers have an initial modulus of 60 to 120 cN / dtex, preferably 70 to 115 cN / dtex, more preferably 90 to 120 cN / dtex.

[0035] Further embodiments relate to the manufacture of cellulosic textile fibers. In one embodiment, the method includes the steps of pretreating a cellulosic material, carrying out cellulose carbamate formation to form cellulose carbamate, dissolving the cellulose carbamate in an aqueous alkaline medium to form a dope, spinning the cellulose carbamate dope in an aqueous spinning medium to form filaments or filament tows, and drawing and optionally cutting the filaments or filament tows to obtain cellulose carbamate fibers having a tensile strength of 0.8-1.8 dtex, a tensile strength of 2.0-2.9 cN / dtex, and an initial modulus of 50-120 cN / dtex. The cellulosic textile fibers produced by the method may be in the form of filaments or staple fibers. The cellulosic material comprises at least 50 wt% cellulose-containing waste, and at least 50 wt% of the cellulose-containing waste is textile waste. During spinning, the filaments or filament tows are stretched at least 70% in length when the temperature of the stretching bath is between 75 and 100°C.

[0036] The embodiments and variations disclosed above in relation to man-made cellulosic textile fibers apply mutatis mutandis to the present method.

[0037] An embodiment includes preparing a cellulose carbamate dope, feeding the dope to a spinning unit exhibiting an aqueous spin bath, coagulating the cellulose carbamate from the dope into the aqueous spin bath to form cellulose carbamate filaments, subjecting the cellulose carbamate filaments to drawing in one or more drawing units, and optionally washing in one or more washing units, and optionally cutting the filaments into fibers to obtain cellulose carbamate filaments or stable fibers. Such spinning is known to those skilled in the art.

[0038] In certain embodiments, the method includes chemically modifying the pretreated cellulosic material in addition to or in place of cellulose carbamate, dissolved cellulose carbamate, or spun cellulosic textile fibers, which may also be referred to as modification by chemical treatment.

[0039] Cellulosic textile fibers can be modified by applying a spin finish with spin finishes such as antistatic agents, flocculants and lubricants.

[0040] As mentioned above, the cellulosic material is pretreated before carbamate formation. In an embodiment, the cellulosic textile material is pretreated by mechanically processing it to a predetermined particle size, and the mechanically processed material is subjected to an acid treatment and an alkali treatment in a cooking liquor, in a desired order, and optionally to a bleaching treatment. In an embodiment, the pretreatment of the cellulose can include the steps of preparing a mixture comprising cellulose and a liquor, and mechanically processing the mixture, for example by shear mixing in a continuous mechanical mixer. Such pretreatment is disclosed, for example, in WO 2021 / 181007.

[0041] During the pretreatment of cellulose, a mixture having a solid content is prepared, said mixture comprising cellulose and a liquid, said mixture preferably having an initial solid content of at least 50% by weight of the mixture, preferably the initial solid content is equal to or greater than 50% by weight of the mixture, for example more than 50% by weight of the mixture, for example 51% by weight of the mixture, 52% by weight of the mixture or for example 55% by weight of the mixture, suitably at least 65% by weight of the mixture, in particular up to 75% by weight of the mixture, most preferably up to 71% or 72% or 73% or 74% by weight of the mixture. Mechanical processing of such ultra-high consistency pulps as these improves the rearrangement of the lamellae of the fiber cell walls and improves the absorption of chemicals such as urea at the molecular level in the mixture or pulp, as compared to low consistency pulps. An initial solid content of at least 50 wt% of the mixture ensures efficient handling of the cellulose, i.e. sufficient shear forces are exerted on the cellulose walls to effectively break them and improve the accessibility of the cellulose fibers to solvents and chemicals. If the initial solids content is less than 50 wt%, for example less than about 45 wt%, the cellulose becomes difficult to handle, so if urea is added, it is advantageous to have a solids content of 50-75 wt%.

[0042] In an embodiment, it is preferred that the solids content does not exceed 90% by weight of the mixture, preferably the solids content does not exceed 75% by weight of the mixture. By maintaining a high consistency pulp with a solids content of not exceeding 90% by weight of the mixture, preferably the solids content does not exceed 75% by weight of the mixture, it is ensured that keratinization or recrystallization due to deactivation by loss of free hydroxyl groups does not occur, and therefore the cell wall structure does not close down to absorb chemicals.

[0043] There is enough space between the above limits that shear forces can act on the cellulose without tearing the fibrils from the cellulose surface, making the fibrils on the fiber cell walls more accessible to solvents and chemicals, which is optimal. Mixtures with solids content at the above limits are optimal for cotton, for example, because the six-layer fibril structure does not become soaked at such solids content. If cotton becomes soaked, the fibril structure will be locked, making it even more difficult to break the fibril structure and increase the accessibility of the cellulose fibers.

[0044] The cellulose can be obtained from various sources and in the form of various pulps. In one embodiment, the cellulose is selected from the group consisting of chemical pulp, mechanical pulp, thermomechanical pulp, chemi-thermomechanical pulp, and mixtures thereof.

[0045] In further embodiments, the chemical pulp is selected from the group consisting of organic sorbent pulp, soda pulp, dissolving pulp, kraft pulp, sulfite pulp, hot water extracted pulp, and mixtures thereof. In embodiments, paper pulp is used. In further embodiments, dissolving grade pulp is used. Recycled pulp, such as deinked pulp, is also useful in embodiments. In certain embodiments, the cellulose is dry dissolving pulp.

[0046] The origin of the raw material is either virgin forms of chemical or dissolving pulp, or recycled raw materials such as recycled paper and / or cardboard containing chemical or dissolving pulp.

[0047] Natural plant fibers, either as is or in the form of chemical pulp or dissolving pulp, are also useful as raw materials. The origin of natural plant fibers may be either in virgin form, or in textile products containing natural plant fibers or textile products containing recycled natural fibers. Natural plant fibers include seed fibers such as cotton and kapok, bast fibers such as hemp, jute, kenaf, ramie, abaca, and linen, leaf fibers such as abaca, sisal, pineapple, and banana, and fruit fibers such as coir.

[0048] In one embodiment, the cellulose is obtained from recycled cellulose selected from the group consisting of paper, cardboard, cotton, cotton linters, wheat straw, rice straw, corn stover, hemp, kenaf, bagasse, bamboo, flax, jute and mixtures thereof. This embodiment of the method is particularly useful for pretreatment of such demanding pulps having multiple fibril layers, such as cotton, cotton linters, hemp, flex, linen and other stem and seed fibers. The cellulose can also be obtained from polycotton blends, in which case the cellulosic component is separated from the non-cellulosic component before pretreatment of the cellulose.

[0049] Likewise, virgin sources of cellulose are suitable as well. Thus, in one embodiment, the cellulose is obtained from virgin cotton, virgin cotton linters, virgin wheat straw, virgin rice straw, virgin corn stover, virgin hemp, virgin kenaf, virgin bagasse, virgin bamboo, virgin flax, virgin jute, and mixtures thereof.

[0050] After pretreatment and carbamate to provide cellulose carbamate, the carbamate is dissolved in an alkaline aqueous medium of the dope in one embodiment to provide a cellulose carbamate dope. In one embodiment, the cellulose carbamate is dissolved in an alkaline aqueous solution containing sodium hydroxide and zinc, such as zinc oxide and / or zinc hydroxide. The addition of zinc has been shown to improve the solubility of the cellulose carbamate and improve the stability of the cellulose carbamate solution. The alkaline solution is made from sodium hydroxide and zinc, thereby forming a zincate salt. Thus, in an embodiment, the alkaline solution includes sodium zincate.

[0051] According to one embodiment, there is provided a method of producing cellulose carbamate filaments or fibers, the method comprising the steps of providing a cellulose carbamate dope comprising cellulose carbamate dissolved in aqueous sodium hydroxide, the dope further exhibiting dissolved zinc compounds, and feeding the dope to a coagulation unit.

[0052] According to a specific embodiment, the cellulose carbamate dope comprises: 6 to 10 wt %, preferably 8 to 10 wt %, of cellulose carbamate (CCA); 5 to 10 wt %, preferably 5 to 7 wt % sodium hydroxide (NaOH); 0.1 to 2 wt %, preferably 0.1 to 1.5 wt %, of zinc oxide (ZnO), and Optionally, processing aids and / or other additives; The weight percentage (wt%) is calculated from the total weight of the cellulose carbamate dope. As mentioned above, zinc can be used in a form other than zinc oxide, and the amount of zinc ranges from 0.08 to 1.6 wt%.

[0053] Thus, each embodiment relates to a cellulose carbamate fiber, in which the cellulose carbamate has an average degree of polymerization (DP) of 180-500, preferably 200-500, in particular 230-350. This degree of polymerization corresponds to an intrinsic viscosity of 146-368 ml / g, 161-368 ml / g and 182-267 ml / g, respectively, based on CED viscosity measurement according to ISO5351:2010 (by dissolving the cellulose carbamate according to the standard, measuring the intrinsic viscosity of the cellulose and calculating the degree of polymerization). The DP is calculated by the following formula: DP 0.905 =0.75[η], where 0.905 and 0.75 are constants characteristic of the cellulose-solvent system, and [η] is the intrinsic viscosity (ml / g). In order to obtain a cellulose carbamate suitable for wet spinning of fibers, it is preferable to reduce the degree of polymerization of the cellulose carbamate from conventional values ​​to the range of values ​​described herein. The cellulose carbamate according to the embodiment has a nitrogen content of 0.3 to 3.0 wt. % of the cellulose carbamate, measured according to the above-mentioned SFS5505:1988.

[0054] Carbamate groups are stable under weakly alkaline conditions, neutral conditions and acidic conditions (e.g., under acidic spinning and drawing conditions). Carbamate groups are hydrolyzed under strong alkaline conditions (e.g., dissolved cellulose carbamate is hydrolyzed in an alkaline aqueous solution with a NaOH content of at least, for example, 6.5% by weight based on the dope). Cellulose carbamate starts hydrolysis instantly after dissolving under alkaline conditions for producing dope. The higher the temperature of the dope and the longer the time from dissolution to coagulation, the faster the hydrolysis rate and the lower the amount of carbamate groups bound in cellulose, i.e., the lower the nitrogen content bound in cellulose. The rate of hydrolysis determines the degree of substitution of cellulose carbamate. Different spinning baths, such as alkaline spinning baths and acidic spinning baths in a wet spinning process, followed by a drawing process, further washing, different finishing and further post-treatment steps, can be used to produce fibers with preferred or more suitable properties. Those skilled in the art can easily determine the appropriate conditions based on this specification and the following examples.

[0055] The post-treatment process may optionally include one or more of the following process steps: a) post-hydrolysis of carbamate groups with hot alkaline solution (e.g., fibers coagulated in an alkaline coagulation bath and with a nitrogen content of 0.8 wt% were subjected to post-hydrolysis in a post-treatment by treatment with a post-hydrolysis solution containing Na2CO3 and NaOH at 95 degrees Celsius for 3 minutes, and the nitrogen content of the recovered fibers was 0.17 wt%); b) acidic and / or neutral and / or alkaline bleaching steps; and / or c) spin finishing. Carbamate groups are stable in acidic systems and hydrolyze in alkaline baths. Thus, fiber properties can be manipulated during coagulation, drawing, further washing and further post-treatment regeneration depending on the alkalinity, temperature and residence time at each step. In particular, such post-treatment conditions are selected and conditioned drawing is used to adjust the hydrolysis rate of cellulose carbamate. The tow of cellulosic filaments is drawn in the first spin bath or immediately after the first spin bath to improve the final initial modulus and tensile strength of the fiber. The shape of the fiber can be controlled by adjusting the degree of substitution of the cellulose carbamate entering the spinning and drawing conditions, for example, rounded oval, bean or leaf-shaped fibers can be obtained as a result of the spinning and drawing of the controlled nitrogen-containing cellulose carbamate, and a smooth surface can be formed.

[0056] In one embodiment, the cellulose carbamate dope is fed to the spinning unit, which shows an aqueous spinning bath containing sulfuric acid and a dissolved aluminum compound. Preferably, the cellulose carbamate dope is fed to the spinning unit through one or more spinnerets. The dope is fed to the spinning unit at a suitable flow rate. According to one embodiment, when the cellulose carbamate dope is fed to the spinning unit, the sulfuric acid reacts with the sodium hydroxide and zinc dissolved in the sodium hydroxide to form sodium sulfate, zinc sulfate and water, so that the spinning bath contains sulfuric acid, zinc sulfate, aluminum sulfate, sodium sulfate and water. The cellulose carbamate coagulates and becomes filament-like while being extruded through the spinnerets.

[0057] In the spin bath, the cellulose carbamate is preferably solidified into cellulose carbamate filaments through one or more spinnerets. Such filaments can be withdrawn from the spin bath and subjected to drawing, optional cutting into fibers, and optional post-treatment in which the filaments or fibers are washed, bleached, and / or spin-finished.

[0058] According to one embodiment, the drawing bath is a hot drawing bath, and the filaments or tows of filaments are immersed in the drawing bath solution. The temperature of the drawing bath is typically in the range of 75-100° C., preferably 85-95° C., more preferably about 90° C. The drawing bath may be the same bath as the spinning bath.

[0059] The method may also include a cutting step after the drawing step, whereby the drawn filaments or filament tows are cut.

[0060] After drawing and optionally cutting, the filaments or fibers may be subjected to post-treatment in a post-treatment device. According to a preferred embodiment, the post-treatment comprises washing, optional post-hydrolysis, bleaching, spin finishing or any combination thereof. In one embodiment, the washing is carried out as a countercurrent wash using water or the effluent of a preceding or subsequent process step. In a preferred embodiment, the post-treatment device operates in a countercurrent principle.

[0061] Finally, the resulting filaments or fibers are dried by known drying methods. As mentioned above, the dissolved cellulose carbamate is spun in an aqueous medium. In addition to spinning in an acidic bath, in another alternative embodiment, the dissolved cellulose carbamate is spun in an alkaline spinning bath, i.e., the aqueous spinning medium is an alkaline spinning bath. In one embodiment, the spinning bath contains sodium carbonate and less than 3 wt%, preferably 0.4-2.99 wt%, in particular less than 2 wt%, for example 1.0-1.99 wt% sodium hydroxide.

[0062] In a further embodiment, the dissolved cellulose carbamate is subjected to spinning in an alkaline spin bath containing sodium hydroxide and sodium carbonate in a weight ratio of 1:9 to 1:30 (i.e. calculated as wt%), preferably in a spin bath (coagulation bath) having a pH above 7.0, in particular a pH of at least 10.

[0063] To produce fibers with improved properties, different spinning baths and different finishing processes can be used. Carbamate groups are stable in acidic systems and hydrolyze in alkaline baths. Thus, in one embodiment, the regeneration of carbamate cellulose occurs during coagulation, drawing and / or post-treatment, so that fiber properties can be manipulated during regeneration, particularly using conditioned drawing and / or conditioned post-treatment.

[0064] The dissolved cellulose carbamate is subjected to wet spinning, while the filaments or filament tows are subjected to drawing in a drawing unit. The drawing bath is a hot bath with a temperature of 75-100°C. In a preferred embodiment, the filaments or filament tows are drawn in the drawing unit by at least 70% of the length, preferably by 90% or more, in particular by 95% or more, or by approximately 70-120% of the length, preferably by 90-120% of the length. Thus, according to an embodiment, the total drawing after solidification of the filaments in the drawing unit is 90% or more, in particular by 95% or more, or by approximately 70-120% of the length, preferably by 90-120% of the length. Stretching by length means total godet stretching by adjusting the stretching stress of the filament or tow of filaments between rotating rollers with different peripheral speeds, for example the peripheral speed of the first roller is 25 m / min and the peripheral speed of the last roller is 50 m / min, thus the resulting godet stretch is 100% by length. Such a high level of stretching contributes to providing a product with a high initial modulus when the temperature of the stretching bath is 75-100°C.

[0065] When the cellulose carbamate is dissolved, hydrolysis of the carbamate begins, and some of the carbamate groups hydrolyze during dissolution, filtration and degassing of the dope. In one embodiment, the nitrogen content of the cellulose carbamate can be adjusted by varying the dissolution conditions, such as time, temperature and / or sodium hydroxide concentration. The nitrogen content for wet spinning of the cellulose carbamate is adjusted to produce textile quality fibers. When coagulated in an acidic spin bath, carbamate hydrolysis stops. When spinning in an alkaline coagulation bath, cellulose regeneration gradually occurs during coagulation and drawing of the tow. In one embodiment, nitrogen removal can continue in the filament formation stage. Spinning parameters and drawing affect the fiber orientation, crystallinity and final shape of the fiber, and therefore the mechanical properties of the fiber. In a further embodiment, the nitrogen content of the final product can be adjusted in the washing and post-treatment stages, where a large portion of the remaining carbamate groups can be removed (hydrolyzed), especially in the alkaline washing stage. In a preferred embodiment, the nitrogen content of the final product is in the range of 0.10-1.2 wt.%, preferably 0.15-1.0 wt.%, in particular 0.2-0.9 wt.%, based on the dry weight of the fiber, which corresponds to a degree of substitution (DS) of the cellulose carbamate in the range of 0.012-0.144.

[0066] A low nitrogen content in the final product is beneficial when improved wet properties are desired, such as low wet elongation and high wet tensile strength / elongation. In one embodiment, the nitrogen content in the final product ranges from 0.10 to 0.75 wt%, corresponding to a degree of substitution of cellulose of 0.012 to 0.09.

[0067] Cellulose fibers are biodegradable, and cellulose carbamates, even when substituted, are biodegradable.

[0068] The dye uptake of cellulose carbamate fibers is very high and is also affected by the final nitrogen content.

[0069] In an acidic spinning bath, the shape of the fiber can be controlled by the amount of aluminum (sulfate) in the spinning bath in addition to the controlled drawing. The amount of aluminum allows for the formation of regular fibers in a controlled manner. In one embodiment, the aluminum sulfate concentration in the acidic spinning bath is 90 g / L or more, preferably 90 to 120 g / L. Aluminum is important because it improves the quality of the fibers produced. In particular, the shape of the fiber is controlled by the amount of aluminum (sulfate) in the spinning bath in addition to the controlled drawing. In particular, aluminum affects the shape of the fiber cross section. Furthermore, aluminum inhibits the crystallization of cellulose in the coagulation process. Amphoteric aluminum compounds affect the acid-base neutralization reaction during the coagulation process. At the same time, the tensile strength and elongation yield of the recovered fibers is improved.

[0070] For purposes of the embodiment, The draw ratio is the ratio between the take-up roller and the extrusion speed, and · The draw ratio is Dr=v, take-up / v, extrusion, where v is the velocity i.e. the velocity entering the spinneret and the velocity exiting the spinneret. Spinneret draw ratio (Dr)=π·a·b·ρ·α·φ 2 / (DTEX 1 (1+Ω / 100) 4 10 7 ) a = 1.1150(1 + fiber moisture % / (100 + fiber moisture %), which is expected to be fiber moisture % = 13.0%. b = 1.1350 (1 + % fiber shrinkage / 100), so we expect % fiber shrinkage = 13.5%. ρ = density of spinning dope at feed temperature (kg / m 3 ) α = cellulose carbamate content of the spinning dope (wt%). φ=Spinneret hole diameter (μm) DTEX = filament linear density (dtex) Ω = total godet extension (%) measured between the first and last godet.

[0071] The main purpose of drawing the filaments is to produce filaments with the desired strength by inducing sufficient orientation of the polymer molecules along the axial direction. A high degree of orientation of the cellulose molecules tends to increase the elastic modulus and tensile strength of the fibers. Surprisingly, it has been found that when spinning in an acidic spinning bath, the spinning is preferably carried out with a spinneret draw ratio in the range of 0.3 to 1.0, preferably 0.4 to 0.9, in particular 0.5 to 0.8. When the fibers of the invention are spun in an alkaline spinning bath, the optimum region of the spinneret draw ratio (Dr) is slightly different, i.e. closer to 1, for example 0.5 to 1.4, preferably 0.8 to 1.2.

[0072] Drawing under controlled process conditions allows the properties of cellulosic fibers to be tailored. The shape of the fiber cross-section can be modified by drawing under controlled process conditions. For example, rounded / elliptical, bean-shaped, or leaf-shaped fiber cross-sections can be obtained as a result of controlled drawing, creating a smooth surface with a cotton-like hand.

[0073] As an example, the fibers are more homogenous and smooth both on the surface and in the internal structure, i.e. cross section, compared to viscose fibers, which have an irregular sawtooth surface (see, for example, Figure 7). The rounded structure of elliptical, bean or leaf-shaped fibers provides a high initial modulus. Furthermore, the relative wet strength, i.e., the breaking tensile strength and elongation, is improved compared to viscose, which has a low breaking tensile strength and elongation. In particular, the relative wet elongation of the cellulosic fiber of the present invention is very good. In one embodiment, the cellulosic fiber product has a wet breaking elongation in the conditioned state of 85-110%, preferably less than 100%, for example 85-99.9%, especially 90-99.9% (wet / dry relative %) of the dry breaking elongation, a wet strength of at least 0.9 cN / dtex, preferably 1.0 cN / dtex or more, and a relative wet strength of 40-80% (wet tensile strength and elongation / dry tensile strength and elongation), preferably 45-80%. (Relative means wet breaking elongation / dry breaking elongation, and a typical wet breaking elongation / dry breaking elongation of viscose is about 120%).

[0074] In cellulosic textile fibers according to embodiments, residual sulfur is absent or essentially absent, especially when alkaline spin baths are used.

[0075] Further embodiments relate to cellulosic textile fibers obtained by the process embodiments, applications of the fibers obtained by the process embodiments, and applications of the cellulosic textile fibers. Thus, one embodiment provides cellulosic textile fibers obtained by the process embodiments described herein above.

[0076] In a further embodiment, the cellulosic textile fibers of any of the above embodiments are used in yarns, textiles, woven fabrics, knit fabrics, textile garments, or nonwoven articles, such as weave tows, flocks, filament yarns, or filament tows.

[0077] Further embodiments relate to articles comprising the cellulosic textile fibers described hereinabove. In one embodiment, the yarn comprises the cellulosic fibers as described above. In a further embodiment, the textile comprises the cellulosic textile fibers as described above. In a particular embodiment, the woven or knitted fabric comprises the cellulosic textile fibers as described above. In a suitable embodiment, the nonwoven article comprises the cellulosic textile fibers as described above. In a further embodiment, the cellulosic fibers in the yarn, textile or textile are combined with cotton fibers, in particular virgin cotton fibers. Thus, in some embodiments, it is possible to replace at least a portion of the cotton fibers, in particular virgin cotton fibers, with man-made cellulosic fibers, thereby reducing, for example, the impact of the textile industry on the environment. The man-made cellulosic fibers of the above-mentioned embodiments have an initial modulus similar to that of cotton fibers, which allows cotton to be replaced with the man-made fibers of the present invention.

[0078] Moreover, it has surprisingly been found that the presence of cellulosic textile fibers as described herein above can be determined by fluorescence detection. Thus, embodiments provide methods for determining the presence of cellulose carbamate fibers or articles containing such fibers.

[0079] In one embodiment, the method comprises exposing an article to UV light, preferably 365 nm UV light, and detecting fluorescence in the wavelength range of 400-520 nm due to said cellulose carbamate fibers. In one embodiment, the article is a yarn, a tow of filaments, a staple fiber, a short cut fiber or a flock. In a further embodiment, the article is a textile garment comprising such fibers, such as a bleached and / or colored article. In accordance with the previous embodiment, when cellulose carbamate is mixed with viscose, lyocell or modal in a fiber, filament, yarn or fabric, the presence of cellulose carbamate in the man-made cellulosic fiber blend can be detected by fluorescence, since other regenerated fibers do not exhibit fluorescence.

[0080] Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. Cellulosic textile fibers according to the embodiments fluoresce. Typically, the emission by fluorescent materials has long wavelengths. Cellulosic textile fibers according to the embodiments emit blue / turquoise light, for example at wavelengths in the range of 450-490 nm, which can be visually observed when the fibers are exposed to UV light, particularly UV light at a wavelength of 365 nm. The fluorescent emission wavelength depends on the excitation wavelength. Fibers according to the embodiments fluoresce at wavelengths in the range of 420-520 nm (blue) when excited with UV light, particularly 365 nm, and at wavelengths in the range of 600-750 nm (red) when excited with 546 nm.

[0081] Some embodiments will now be illustrated by the following examples.

[0082] Working Example Example 1. Chemical pretreatment and carbamate formation Recycled mixed color sorted cotton textile waste with a CED viscosity (ISO5351:2010) of 800±200 ml / g containing 4.0±2.8 wt% non-cellulosic fibers (mainly polyester but with traces of nylon, isoprene-containing materials (elastic bands), and polyethylene / polypropylene) was mechanically shredded to disrupt the fabric structure and form shreds with fibers of 6 mm fiber length. The shredded material was chemically pretreated using a two-stage cooking procedure and bleaching. In the first acid stage, the material was treated with sulfuric acid. In the second alkaline stage, the washed acid-treated material was chemically pretreated with sodium hydroxide to hydrolyze most of the polyester. The average yield in the alkaline stage was 92% solids for oven-dried material. The bleaching stage, which included both ozone and alkaline hydrogen peroxide bleaching stages, further adjusted the degree of polymerization and polydispersity of cellulose. The material obtained from the bleaching process was appropriately dewatered for the subsequent carbamate process. The carbamate process was carried out as described in FI Patent No. 112869, FI Patent No. 112795 and FI Patent Application Publication No. 20195717. In the carbamate stage, the degree of polymerization and the degree of substitution (carbamation level) of the cellulose were adjusted. The viscosity of the chemically pretreated cellulose carbamate material was 195-230 ml / g based on CED viscosity measurements according to ISO 5351:2010. The corresponding degree of polymerization values ​​were 248 and 297. The cellulose carbamate used for these examples has a nitrogen content of 1.6-1.9% by weight of the cellulose carbamate, measured using SFS 5505:1988.

[0083] Example 2. Wet spinning of cellulose carbamate dope in an acidic spin bath The cellulose carbamate obtained from the carbamate formation process was further dissolved and cellulose carbamate fibers were produced by a wet spinning process. That is, the milled air-dried cellulose carbamate powder was slurried and dissolved in a sodium zincate (zinc oxanate) solution (zinc amount 0.96 wt%) to achieve a target cellulose carbamate content of 6.5 wt% (samples 1 and 4) or 7.0 wt% (samples 2 and 3) and sodium hydroxide content of 6.5 wt%. The cellulose carbamate dope obtained from the dissolution process was then filtered using a two-stage back-flush filtration process with a 20 μm filter medium in the second filtration stage. The wet spinning of the filtered and degassed cellulose carbamate dope was carried out using an acid spin bath optimized for the cellulose carbamate process, for example, containing sodium sulfate, free sulfuric acid and aluminum sulfate 80 g / L or 92 g / L. The cellulose dope was coagulated in a spin bath and drawn in a hot bath. The draw ratios used were 0.58 for sample 1, 0.72 for samples 2 and 3, and 0.96 for sample 4. As a comparative example, spinning at a draw ratio of 1.07 was tested. The fibers were found to be insufficiently strong to withstand the drawing required to achieve the targeted fiber properties, with linear densities below 2.0 dtex. The spun filament tows were cut into staple fibers with a cut length of 40 mm, except for sample 4, which was used as filament. The linear density (dtex) of the fibers was measured according to ISO 1973:2021, and the tensile strength (cN / dtex), elongation (%) and initial modulus (cN / dtex) of the fibers were measured according to ISO 5079:2020. The dry fibers were conditioned for at least 24 hours at a relative humidity of 65 ± 2% and a temperature of 20 ± 2 °C. The test speed was 20 mm / min, the gauge length was 20 mm, and the average value of 20 measurements (Favigraph, Textechno) was calculated. With an aluminum sulfate concentration of 80 g / L in the spinning bath, the samples were not stable enough for conditional drawing, and sawtooth fibers were formed that solidified too quickly and did not meet the required strength of the fibers (see Figure 4). A higher amount of aluminum sulfate (92 g / L) was used in the successful samples 1-4. The fiber properties are shown for samples 1 to 4 in Table 1. Representative samples of viscose, Tencel, modal, and cotton were measured for reference.

[0084] Example 3. Wet spinning of cellulose carbamate dope in an alkaline spin bath The cellulose carbamate obtained from the carbamate formation process was further dissolved and cellulose carbamate fibers were produced by a wet spinning process. That is, the milled air-dried cellulose carbamate powder was slurried and dissolved in a sodium zincate (zinc oxanate) solution (zinc content 0.96 wt%) to achieve a target cellulose carbamate content of 6.5 wt% (samples 5, 7, 8) or 8.4 wt% (samples 6, 9), and a sodium hydroxide content of 6.5 wt%. The cellulose carbamate dope obtained from the dissolution process was then filtered using a two-stage back-flush filtration process with a 20 μm filter medium in the second filtration stage.

[0085] Wet spinning of the filtered and degassed cellulose carbamate dope was carried out using an alkaline spin bath optimized for the cellulose carbamate process, containing 24-27 wt% sodium carbonate and 1.4 wt% sodium hydroxide. The cellulose dope was coagulated in the spin bath and the applied godet stretching stress was 101%-113% ± 7% under hot bath conditions. The high stretchability of the filaments in the tow allowed the yarn to be manipulated over a wide range. The draw ratios used were 0.72 for sample 5, 0.54 for samples 6 and 8, and 0.70 for samples 7 and 9. As a comparative example, spinning at a draw ratio of 1.01 was tested (cellulose carbamate content 6.9 wt%, stretch ratio 72%, titer 1,11). It was found that under these conditions the fibers did not have enough strength to withstand the stretching required to achieve the target fiber properties. The filament tows obtained from spinning were cut into staple fibers with a cut length of 40 mm.

[0086] Fiber linear density, fiber tensile strength, elongation and initial modulus of staple fibers were measured according to ISO 1973:2021 and ISO 5079:2020 as described in Example 2. Fiber properties are shown in Table 1 for samples 5-9. Samples 8 and 9 as well as the viscose sample were also measured in the wet stage (wetting time 120 s) to investigate the wetting properties of the fresh fibers. The breaking elongation (%) of wet samples 8 and 9 was lower than that in the dry state, with relative wet elongation of 99% and 88%, respectively.

[0087] Example 4. Wet spinning of cellulose carbamate dope in an alkaline spin bath The cellulose carbamate obtained from the carbamate formation process, with an intrinsic viscosity of less than 225 ml / g, was dissolved and prepared into cellulose carbamate fibers by a wet spinning process. That is, the milled air-dried cellulose carbamate powder was slurried and dissolved in a sodium zincate (zinc oxanate) solution (zinc content 0.96 wt%) to achieve a target cellulose carbamate content of 8.0 wt% or more and a sodium hydroxide content of 6.5 wt% or more. The cellulose carbamate dope obtained from the dissolution process was then filtered using a two-stage back-flush filtration process with a 20 μm filter medium in the second filtration stage.

[0088] Wet spinning of the filtered and degassed cellulose carbamate dope was carried out using an alkaline spin bath optimized for the cellulose carbamate process, containing 25 wt% sodium carbonate and 1.5 wt% sodium hydroxide, at 45 degrees Celsius. The cellulose dope was extruded (spinning orifice diameter 50 μm) into the spin bath and coagulated in the spin bath, with the applied godet stretching stress ranging from 81% to 115% in a hot bath at 90 degrees Celsius. The high stretchability of the filament tows allowed the yarn to be manipulated over a wide range.

[0089] Samples 10-13 were prepared using the following process details.

[0090] Sample 10, cellulose carbamate, intrinsic viscosity 187 ml / g, cellulose carbamate content in the dope 8.50 wt%. The elongation stress was 81%, and the draw ratio was 1.12.

[0091] Sample 11, cellulose carbamate, inherent viscosity 224 ml / g, cellulose carbamate content in the dope 8.03 wt%. The elongation stress was 98%, and the draw ratio was 1.02.

[0092] Sample 12, cellulose carbamate, intrinsic viscosity 200 ml / g, cellulose carbamate content in the dope 9.39 wt %, elongation stress 115%, draw ratio 1.00.

[0093] Sample 13, cellulose carbamate, intrinsic viscosity 209 ml / g, cellulose carbamate content in the dope 8.55 wt%. The elongation stress was 106%, and the draw ratio was 0.93.

[0094] Fiber linear density, fiber tensile strength, elongation, and initial modulus of staple fiber were measured according to ISO 1973:2021 and ISO 5079:2020 as described in Example 2. Fiber properties are shown in Table 1, Samples 10-13.

[0095] Example 5. Preparation of nonwoven articles Nonwoven samples were prepared using Sample 1 and standard viscose with titanium dioxide (designated A in Figures 6 and 7) in a 50:50 weight ratio. An optical microscope (Zeiss Imager) was used to analyze the fibers in the composite. The cellulose carbamate fibers (CCA, designated B in Figures 6 and 7) were brighter, more uniform, and less streaked in the longitudinal direction (see Figure 6). The cellulose carbamate fibers were smooth leaf / bean shaped fibers compared to the sawtooth shaped viscose fibers (see Figure 7).

[0096] Example 6. Determination of terephthalic acid content The content of terephthalic acid in cellulose carbamate fiber, sample 2 (cut length 40 mm), produced as described in Example 2, was measured by GC / MS (gas chromatography-mass spectrometry) system. The sample was acidified with hydrochloric acid to pH<3 and dried in an oven overnight. Free terephthalic acid was extracted from the sample with pyridine / methanol solvent and concentrated to 5 ml. The extracted terephthalic acid was methylated and analyzed by GC / MS. The free terephthalic acid content in the sample was calculated against an external calibration standard. The amount of terephthalic acid was 5 mg / kg (of cellulose carbamate fiber).

[0097] Example 7. Determination of terephthalic acid content The content of terephthalic acid in cellulose carbamate fiber, sample 2 (cut length 40 mm) produced as described in Example 2, was measured by GC / MS (gas chromatography-mass spectrometry) system. The sample was first refluxed with sodium hydroxide (10 wt%) for 4 hours to hydrolyze the polyethylene terephthalate in the sample. Terephthalic acid was extracted from the sample, dissolved in pyridine / methanol solvent, and concentrated to 5 ml. The extracted terephthalic acid was methylated and analyzed by GC / MS. The terephthalic acid content was calculated against an external calibration standard. The amount of terephthalic acid was 309 mg / kg (of cellulose carbamate fiber).

[0098] Table 1 shows various strength properties of artificial cellulose carbamate fiber products spun in an acidic bath for samples 1 to 4 and in an alkaline bath for samples 5 to 13, along with reference values ​​for other artificial cellulose fiber materials.

[0099] [Table 1] Some of the samples listed in Table 1 were analyzed under a microscope, the results of which are shown in the accompanying figures.

[0100] 1 shows tensile strength elongation strain curves for reference materials and manmade cellulosic textile fibers in accordance with at least some embodiments of the present invention, read at 6% elongation from top to bottom: Tencel, cotton, Modal, Sample 5, Sample 3, Viscose, Sample 7 (wet), Viscose (wet). Tensile strength cN / dtex is shown on the y-axis and percentage elongation on the x-axis.

[0101] 2 is a light micrograph showing a fiber according to at least some embodiments of the present invention. The fiber shown in the figure was prepared as described in Example 2, Sample 2.

[0102] 3 is a light micrograph showing the cross-section of a man-made cellulosic fiber according to at least some embodiments of the present invention. The fiber having a leaf / bean cross-section was prepared as described in Example 2, Sample 2.

[0103] FIG. 4 is an electron micrograph showing the sawtooth cross section of a fiber sample.

[0104] 5 is an electron micrograph showing the cross-section of a fiber according to at least some embodiments of this invention. Fibers having an elliptical cross-section are prepared as described in Example 3, Sample 5.

[0105] FIG. 6 is a light micrograph showing that cellulose carbamate fibers according to at least some embodiments of the present invention, prepared as described in Example 3, Sample 1, have better uniformity and brightness than a reference viscose fiber.

[0106] 7 is a light micrograph showing the cross-sectional structural differences of cellulose carbamate fibers according to at least some embodiments of the present invention prepared as described in Example 2, Sample 1, compared to a reference viscose fiber. The cellulose carbamate fibers according to the embodiments are smooth and have a leafy / bean shape, whereas the reference viscose fiber has a sawtooth or jagged shape.

[0107] It is to be understood that the disclosed embodiments of the invention are not limited to the particular structures, process steps, or materials disclosed herein, but extend to equivalents thereof that would be recognized by one of ordinary skill in the relevant arts. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0108] Throughout this specification, reference to an embodiment or an embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, although the phrases "in one embodiment" or "in an embodiment" appear in various places throughout this specification, they do not necessarily all refer to the same embodiment. For example, when referring to a numerical value using terms such as about, substantially, etc., the exact numerical value is also disclosed.

[0109] As used herein, a plurality of items, structural elements, components, and / or materials may be presented in a common list for convenience. However, these lists should be construed as if each member of the list were individually identified as a separate and unique member. Thus, the individual members of such lists should not be construed as de facto equivalents of other members of the same list solely based on their presentation in a common group, absent indication to the contrary. Furthermore, various embodiments and examples of the invention may be referred to herein along with alternatives for the various components thereof. Such embodiments, examples, and alternatives are not to be construed as de facto equivalents of each other, but rather as being considered as separate and autonomous representations of the invention.

[0110] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as example lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. However, those skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0111] While the above-described examples illustrate the principles of the present invention in one or more particular applications, it will be apparent to those skilled in the art that numerous changes in form, use and details of implementation may be made without the exercise of inventive faculty and without departing from the principles and concepts of the present invention. Accordingly, it is not intended that the present invention be limited except as by the scope of the claims which follow.

[0112] In this specification, the verbs "comprise" and "include" are used as open-ended limitations that do not exclude or require the presence of any unrecited features. Features recited in the dependent claims may be freely combined with each other, unless otherwise expressly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e., the singular form, throughout this specification does not exclude the plural form. [Industrial Applicability]

[0113] At least some embodiments of the present invention find industrial application in the production of man-made fibers for the textile industry. Fibers with elongation properties similar to cotton can be provided by the present technology. In embodiments of the present technology, fibers are provided that are soft enough to be easily used in yarn manufacturing processes. Cellulosic textile fibers, optionally in combination with cotton fibers, such as virgin cotton fibers, can generally be used in yarns, textiles, woven or knitted fabrics, textile garments, and nonwoven fabrics.

Claims

1. An artificial cellulosic textile fiber, comprising: A linear density of 0.8 to 1.8 dtex; A tensile strength and elongation of 2.0 to 2.9 cN / dtex; and an initial modulus of 50 to 120 cN / dtex; A cellulosic textile fiber, wherein at least 50 wt. % of the raw material of the textile fiber is cellulose-containing waste, and at least 50 wt. % of the cellulose-containing waste is textile waste.

2. 2. The cellulosic textile fiber according to claim 1, wherein the cellulosic textile fiber comprises, by dry weight, at least 90 wt.%, in particular at least 95 wt.%, of cellulose.

3. 3. The cellulosic textile fiber of claim 1 or 2, wherein the raw material of the textile fiber is 100% textile waste.

4. The cellulosic textile fiber of any one of claims 1 to 3, wherein the cellulosic textile fiber is a cellulose carbamate fiber.

5. 5. The cellulosic textile fibres according to any one of claims 1 to 4, wherein the cellulosic textile fibres have a breaking elongation of 7 to 19% and a nitrogen content of 0.10 to 1.2 wt.-%, preferably 0.15 to 1.0 wt.-%, in particular 0.2 to 0.9 wt.-%, based on the dry weight of the fibre.

6. 6. The cellulosic textile fiber according to any one of claims 1 to 5, wherein the cellulosic textile fiber has a wet breaking elongation in the conditioned state of 85 to 110%, preferably less than 100%, for example 85 to 99.9%, in particular 99.9% (wet / dry relative %) of the dry breaking elongation.

7. The cellulosic textile product fiber according to any one of claims 1 to 6, having a wet tensile strength / elongation of at least 0.9 cN / dtex, preferably 1.0 cN / dtex or more, and a relative wet tensile strength / elongation (wet tensile strength / dry tensile strength / elongation) of 40 to 80%, preferably 45 to 80%.

8. The cellulosic textile fiber is a linear density of 1.1 to 1.5 dtex, preferably 1.2 to 1.4 dtex; A tensile strength and elongation of 2.1 to 2.8 cN / dtex, preferably 2.2 to 2.7 cN / dtex; The cellulosic textile fibres according to any one of claims 1 to 7, exhibiting an initial modulus of 60 to 120 cN / dtex, preferably 70 to 150 cN / dtex.

9. 1. A method for producing cellulosic textile fibers, comprising: pre-treating a cellulosic material comprising at least 50 wt. % cellulose-containing waste, at least 50 wt. % of which is textile waste; Carrying out cellulose carbamation to form cellulose carbamate; dissolving cellulose carbamate in an aqueous alkaline medium to form a cellulose carbamate dope; spinning the cellulose carbamate dope in an aqueous spinning medium to form filaments or filament tows while drawing the filaments or filament tows at least 70% in length when the temperature of the drawing bath is between 75 and 100° C.; The method of the present invention provides a cellulose carbamate fiber having a linear density of 0.8 to 1.8 dtex, a tensile strength and elongation of 2.0 to 2.9 cN / dtex, and an initial modulus of 50 to 120 cN / dtex.

10. 10. The method of claim 9, wherein the pretreated cellulosic material, cellulose carbamate, dissolved cellulose carbamate or spun cellulosic textile fibers are modified by chemical treatment.

11. 11. The method of claim 9 or 10, wherein the cellulosic material is pretreated by mechanically treating it to a predetermined particle size, and then the mechanically treated material is subjected to, in a desired order, acid and alkali treatments in a cooking liquor, and optionally a bleaching treatment.

12. The method according to any one of claims 9 to 11, wherein the aqueous alkaline medium of the dope is an alkaline solution containing sodium hydroxide and zinc.

13. The method according to any one of claims 9 to 12, wherein the aqueous spinning medium is an alkaline spinning bath.

14. 14. The method according to claim 13, wherein the alkaline spin bath comprises sodium carbonate and less than 3 wt. %, preferably 0.4 to 2.99 wt. %, in particular less than 2 wt. % sodium hydroxide.

15. The method according to claim 13 or 14, wherein the alkaline spin bath comprises sodium hydroxide and sodium carbonate in a weight ratio of 1:9 to 1:

30.

16. The method according to any one of claims 9 to 12, wherein the aqueous spinning medium is an acidic spinning bath containing aluminium sulphate in a concentration of at least 90 g / L, preferably between 90 and 120 g / L.

17. The method according to any one of claims 9 to 16, wherein the spinning has a spinneret draw ratio in the range of 0.3 to 1.0, preferably 0.4 to 0.9, in particular 0.5 to 0.

8.

18. 18. The method according to claim 9, wherein the total stretching of the filaments after solidification in the stretching unit is at least 90% in length, in particular at least 95% in length, generally between 70 and 120%, preferably between 90 and 120% in length.

19. Cellulosic textile fibres obtainable by the method according to any one of claims 9 to 18.

20. Use of cellulosic textile fibres as claimed in claims 1 to 8 or 19, or as obtained by the method according to any one of claims 9 to 18, in yarns, textiles, woven or knitted fabrics, textile garments or nonwoven fabrics.

21. 20. A yarn, textile, woven or knitted fabric, textile garment or nonwoven article comprising a cellulosic textile fibre as defined in any one of claims 1 to 8 or 19, or as obtained by the method of any one of claims 9 to 18.

22. 22. The yarn, textile, woven or knitted fabric, or textile garment of claim 21 , wherein the fibers are combined with cotton fibers, in particular virgin cotton fibers.

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