Cellulosic textile fibre

Abstract

According to an example of the invention, a man-made cellulose fabric fiber is provided having a linear density of 0.8 to 1.8 dtex, a toughness of 2.0 to 2.9 cN / dtex, and an initial modulus of 50 to 120 cN / dtex. The cellulose fabric fiber comprises cellulose-based materials, wherein at least 50 wt% of the fabric fiber raw material is cellulose-containing waste and at least 50 wt% of the cellulose-containing waste is fabric waste.

Description

[Technical Field]

[0001] This invention relates to cellulose fabric fibers. The invention further relates to a method for manufacturing cellulose fabric fibers. It also discloses the uses of the cellulose fabric fibers and articles comprising the cellulose fabric fibers. [Previous Technology]

[0002] Cellulose, the most abundant renewable organic material on Earth, exhibits outstanding properties for fiber applications. Despite the environmental challenges of the viscous process, it remains the most widely used technology for manufacturing regenerated cellulose fibers and membranes. Therefore, there is a need to develop simpler and more sustainable fabric fibers with improved properties compared to traditional production processes.

[0003] European patent applications EP 1509548 A1 and EP 1470162 A1 both describe the production of cellulose carbamates from high-quality cellulose solutions. Cellulose carbamates are known to be an environmentally friendly alternative for the production of synthetic cellulose fibers. International patent application WO 2021 / 038136 also describes spun fibers derived from cellulose carbamates. However, despite having, for example, acceptable strength properties, cellulose carbamate technology has not yet been able to produce fibers of textile quality. [Summary of the Invention]

[0004] Purpose and Overview of the Invention

[0005] The objective of this invention is to overcome at least some of the problems associated with prior art and to provide synthetic cellulose fibers with textile quality. Through the implementation of the invention, it has been surprisingly found that synthetic cellulose fibers with improved properties can be obtained by modifying the conditions of the spinning bath and the fiber stretching. The method of this invention particularly allows for the production of cellulose fabric fibers from waste materials in at least a portion, and also yields fibers that are strong enough for the textile industry.

[0006] This invention is defined by the features of the independent items. Certain specific embodiments are defined in the appendices.

[0007] According to a first aspect of the present invention, a man-made cellulose fabric fiber is provided, the fiber having a linear density of 0.8 to 1.8 dtex, a toughness of 2.0 to 2.9 cN / dtex, and an initial modulus of 50 to 120 cN / dtex. The man-made cellulose fabric fiber is wherein at least 50 wt% of its raw material is cellulose-containing waste and at least 50 wt% of the cellulose-containing waste is fabric waste.

[0008] According to a second aspect of the present invention, a method for manufacturing cellulose fabric fibers is provided, the method comprising the following steps: pretreating a cellulose-based material containing at least 50 wt% cellulose-containing waste, wherein at least 50 wt% of the cellulose-containing waste is fabric waste; performing cellulose carbamate esterification to form cellulose carbamate; dissolving the cellulose carbamate in an aqueous alkaline medium to form a cellulose carbamate spinning solution; spinning the cellulose carbamate spinning solution in an aqueous spinning medium to form filaments or filament tows, wherein the filaments or filament tows are subjected to a stretch of at least 70% by length at a temperature of 75 to 100°C in a stretching bath to obtain cellulose carbamate fibers having a linear density of 0.8 to 1.8 dtex, a toughness of 2.0 to 2.9 cN / dtex, and an initial modulus of 50 to 120 cN / dtex.

[0009] According to the third state of the present invention, it provides cellulose fibers that are obtainable by the second state of the present invention.

[0010] According to a fourth embodiment of the present invention, the use of the cellulose fabric fibers described in any of the above embodiments of the present invention in an article is provided.

[0011] According to a fifth aspect of the present invention, an article comprising the cellulose fabric fibers described in any of the above aspects of the present invention is provided.

Implementation Method

[0019] Detailed Description

[0020] Man-made cellulose fibers are fibers whose structure and properties are modified during the manufacturing process. Man-made fibers differ from natural fibers (such as silk, cotton, and wool). Man-made cellulose fibers are made from the same cellulose polymers that constitute the structural fibers of, for example, cotton, hemp, flax, and wood. In examples of man-made cellulose fibers, the cellulose is obtained in a modified state, such as cellulose from wood pulping operations, or cellulose modified to regenerate usable cellulose-based fibers.

[0021] Linear density is a measure of the mass per unit length of fiber, used by fiber manufacturers as a measure of fineness. Linear density, expressed in decitex, is the weight in grams of 10,000 m of fiber length. Decitex is an approved SI unit for linear density. Linear density in dtex is measured according to ISO 1973:2021.

[0022] Toughness is a measure of fiber strength. It is usually defined as the fiber's ultimate (breaking) force (in grams per force) divided by its linear density. Toughness is defined as the ratio between the specimen's ultimate (breaking) force and the load, and the linear density. The toughness of a specimen can be expressed in units such as cN / dtex, grams per tex, grams per denier, and newtons per tex. Fiber toughness (cN / dtex) is measured according to ISO 5079:2020.

[0023] In textiles, the term initial modulus describes the initial tensile strength of a fabric fiber and is measured using ISO 5079:2020. In other words, it is a measure of the fiber's resistance to small initial stretch. A high modulus indicates high tensile strength. The tangent angle between the initial curve and the horizontal axis is equal to the ratio of stress to strain. This ratio is called the initial modulus, but in textile science, it is referred to as Young's modulus. The initial modulus of a fabric fiber depends on its chemical structure, crystallinity, fiber orientation, etc. The initial modulus is tan α = stress / strain.

[0024] Elongation at break is the fiber elongation caused by the breaking force. Elongation at break (%) = elongation at break x 100 / original length of the specimen. It is measured using ISO 5079:2020.

[0025] The nitrogen content in cellulose fabric fibers or cellulose carbamates refers to the amount of nitrogen in cellulose that is bound as carbamate groups. In this context, it is given as a percentage by weight of the total weight of the fibers or cellulose carbamates (depending on the measurement time) and measured in accordance with SFS 5505:1988.

[0026] In this invention, cellulose fabric fibers refer to fibers in the form of short fibers, chopped fibers, tufts, filament yarns, and filament bundles. Cellulose fabric fibers in this invention also refer to fibers used in nonwoven applications. It should also be understood that the term filament in this description encompasses filament bundles.

[0027] The raw materials can be different types of cellulose-rich textile waste, such as post-consumer waste, pre-consumer waste, industrial textile waste, or by-products (side stream) from textile manufacturing. Textile waste can be collected and sorted. The terms "recycled waste" and "waste" are also used interchangeably.

[0028] In this specification, when weight percentage (wt-%) is used, it means the weight percentage in the relevant material unless otherwise indicated.

[0029] Unless otherwise specified, the term hot bath should be understood to mean a bath with a temperature in the range of 75 degrees Celsius to 100 degrees Celsius.

[0030] As described above, the embodiments of the present invention relate to man-made cellulose fabric fibers, particularly man-made cellulose fabric fibers spun by wet spinning.

[0031] In one embodiment, the man-made cellulose fabric fiber has a linear density of 0.8 to 1.8 dtex, a toughness of 2.0 to 2.9 cN / dtex, and an initial modulus of 50 to 120 cN / dtex, and comprises cellulose-based materials. Fibers having a dtex at the lower end of this range (such as 0.8 to 1.3) are suitable for providing lightweight textiles, for example, from fibers that typically have a fineness of about 1.5 or less. Cotton fibers typically have a toughness at the upper end of this range, while conventionally wet-spun man-made cellulose fibers typically have a toughness at the lower end of this range. The cN / dtex value of the man-made cellulose fabric fiber according to the embodiment is measured in a dry state, i.e., in a conditioned state. The value range of 50 to 120 cN / dtex is higher than that of conventional viscose fibers, which typically have a modulus in the range of 20 to 40 cN / dtex when measured in a dry state.

[0032] The cellulose fabric fiber comprises cellulose-based materials, wherein at least 50 wt% of the fabric fiber raw material is cellulose-containing waste and at least 50 wt% of the cellulose-containing waste is fabric waste. According to one embodiment, the fabric fiber raw material is 100% fabric waste, that is, only fabric waste is used as raw material.

[0033] In one embodiment, the fiber has 0.00005 to 0.5 wt% of terephthalate and / or terephthalic acid and / or unhydrolyzed or partially unhydrolyzed polyester, particularly polyethylene terephthalate, which is determined by gas chromatography-mass spectrometry (GC-MS), as explained in more detail in the examples below. This amount may be, for example, less than 0.2 wt%, preferably less than 0.1 wt%. The presence of terephthalate and / or terephthalic acid and / or unhydrolyzed or partially unhydrolyzed polyester is an indication that textile waste has been used as a raw material for the manufacture of cellulose carbamate.

[0034] Cellulose-based materials may contain virgin cellulose and / or may contain recycled cellulose from sources such as jute, hemp, kenaf, cotton, bagasse, and the like. The man-made cellulose fibers of embodiments according to the invention exhibit good abrasion resistance, i.e., good strength properties. The fibers have an initial modulus similar to cotton, thereby enabling the fibers of the embodiments described herein to provide good strength properties for yarns, yarns, and fabrics made from combinations of virgin cellulose (e.g., cotton) and the fibers of the present invention.

[0035] Cellulose fabric fibers contain at least 50 wt% of the fabric fiber raw material as cellulose-containing waste and at least 50 wt% of the cellulose-containing waste as fabric waste. The fibers of the present invention and their manufacturing methods thus allow the manufacture of fabric fibers that incorporate recycled materials and still possess properties that permit their use in the textile industry (such as for woven fabrics).

[0036] Embodiments of the present invention provide cotton-like synthetic fibers. The elongation of the fibers of the present invention can be adjusted, for example, by stretching and modifying the carbamate content, so that the fibers exhibit an elongation typically in the range of about 5% to 20%, preferably about 7% to 19%. Therefore, fibers having elongation properties similar to cotton can be provided by the technology of the present invention. In embodiments of the present invention, fibers of the aforementioned types are provided, which have sufficient flexibility for easy use in yarn manufacturing processes.

[0037] Special rayon fibers (such as Modal) have improved mechanical wet properties. However, the cellulosic fabric fibers of the present invention are more economically viable and more like cotton, while still possessing the reinforcing properties described above.

[0038] In one embodiment, the cellulose fabric fibers contain 90 wt% or more, particularly 95 wt% or more, of cellulose on a dry weight basis. Non-cellulose components (such as plastics, nylon, polyethylene, polypropylene, elastane) and possible nitrogen-containing impurities (such as biuret) may also be present in small amounts. Furthermore, spinning finishing chemicals are used to modify processability in, for example, carding and / or yarn production. Other additives may be incorporated into the cellulose fabric fibers as needed. Chemicals may be used to modify processability and / or physical properties, such as the tensile strength, modulus, or elasticity of the final product. Chemicals may act as tracers as needed. Processing aids, surfactants, lubricants, wetting agents, stabilizers, color and brightness modifiers, matting agents (such as titanium dioxide, e.g., anatase or rutile titanium dioxide), dyes, pigments, flame retardants, fillers, antistatic agents, and fiber friction-reducing auxiliaries may also be present in the cellulose fabric fibers.

[0039] In a further embodiment, the cellulose-based material comprises recycled waste, wherein preferably at least 25 wt% and more preferably at least 50 wt% of the cellulose-based material is formed from recycled textile waste. As discussed above, at least 50 wt% of the textile fiber raw material 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 cellulose-containing waste as raw material. Of this cellulose-containing waste, at least 50 wt% is textile waste and the textile waste may be at least 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 wt% of cellulose-containing waste. As discussed below, the cellulose-containing waste may also include, for example, paper or paperboard waste.

[0040] The synthetic fibers obtained by the method of the present invention can be combined with cotton fibers, and they can be interwoven to provide threads or yarns with properties of interest. The cotton fibers can be virgin or recycled cotton fibers, such as mechanically recycled cotton fibers, or blends containing virgin and mechanically recycled cotton fibers can be used with the fibers of the present invention. Thus, synthetic fibers (e.g., manufactured from recycled cotton as needed) can be used to replace at least a portion of virgin cotton in threads, yarns, textiles, and other articles containing cellulose fibers.

[0041] In a further embodiment, the cellulose fabric fiber is a cellulose carbamate fiber. In one embodiment, the cellulose fabric fiber has an elongation of 7 to 19% of its fiber length before breakage and a nitrogen content of 0.10 to 1.2 wt% (preferably 0.15 to 1.0 wt%) and particularly 0.3 to 0.9 wt% based on fiber dry weight. In one embodiment, the cellulose fabric fiber has a wet strength of at least 0.9 cN / dtex and a relative wet strength (wet toughness / dry toughness) of 40 to 80%, preferably 45 to 80%.

[0042] In a specific embodiment, the cellulose fabric fibers exhibit a linear density of 1.1 to 1.5 dtex, preferably 1.2 to 1.4 dtex. The cellulose fabric fibers may also have a toughness of 2.1 to 2.8 cN / dtex, preferably 2.4 to 2.7 cN / dtex. According to another embodiment, the cellulose fabric fibers have an initial modulus of 60 to 120 cN / dtex, preferably 70 to 115 cN / dtex, and more preferably 90 to 120 cN / dtex.

[0043] A further embodiment relates to the manufacture of cellulose fabric fibers. In one embodiment, the method includes the following steps: pretreating a cellulose-based material; performing cellulose carbamate esterification to form cellulose carbamate; dissolving the cellulose carbamate in an aqueous alkaline medium to form a spinning solution; spinning the cellulose carbamate spinning solution in an aqueous spinning medium to form filaments or filament bundles; stretching the filaments or filament bundles and cutting them as needed to obtain cellulose carbamate fibers having a linear density of 0.8 to 1.8 dtex, a toughness of 2.0 to 2.9 cN / dtex, and an initial modulus of 50 to 120 cN / dtex. The cellulose fabric fibers manufactured by this method can be in the form of filaments or staple fibers. The cellulose-based material contains at least 50 wt% of cellulose-containing waste, wherein at least 50 wt% of the cellulose-containing waste is fabric waste. During spinning, the filament or filament bundle is subjected to a stretch of at least 70% by length when the temperature of the stretching bath is 75 to 100°C.

[0044] The embodiments and variations of the artificial cellulose fabric fibers disclosed above are applicable to this method after necessary modifications.

[0045] An embodiment includes providing a cellulose carbamate spinning solution, feeding the spinning solution into a spinning unit containing an aqueous spinning bath, coagulating the cellulose carbamate from the spinning solution into the aqueous spinning bath to form cellulose carbamate filaments, subjecting the cellulose carbamate filaments to stretching in one or more stretching units, washing them as needed in one or more washing units, and cutting the filaments into fibers as needed, thereby obtaining cellulose carbamate filaments or stable fibers. Spinning itself is known to those skilled in the art.

[0046] In a specific embodiment, the method comprises a pretreated cellulose material that has been chemically modified to replace or substitute for cellulose carbamate, or dissolved cellulose carbamate, or spun cellulose fabric fibers. Chemical modification may also be referred to as chemical treatment modification.

[0047] Cellulose fabric fibers can be modified by undergoing spinning finishing with spinning finishing agents (such as antistatic agents, adhesives and lubricants).

[0048] As described above, the cellulose-based material is pretreated before carbamate esterification. In one embodiment, the cellulose-based fabric material is prepared by mechanically processing it to a predetermined particle size, followed by subjecting the mechanically processed material to acidic and alkaline treatments in a cooking liquor in a desired order, and bleaching as needed. In the embodiment, the pretreatment of cellulose may include the following steps: providing a mixture comprising cellulose and a liquid and mechanically processing the mixture, for example, by shear mixing in a continuous mechanical mixing apparatus. This pretreatment is disclosed, for example, in WO 2021 / 181007.

[0049] During cellulose pretreatment comprising providing a mixture having a solids content, the mixture comprising cellulose and liquid, preferably having an initial solids content of at least 50% by weight of the mixture, preferably 50% or more by weight of the mixture, for example, more than 50% by weight of the mixture, such as 51% by weight of the mixture, 52% by weight of the mixture, or for example 55% by weight of the mixture, suitablely at least 65% by weight of the mixture, particularly at most 75% by weight of the mixture, and most preferably at most 71% or 72% or 73% or 74% by weight of the mixture. Mechanical processing of ultra-high consistency pulp (such as mechanical processing compared to low consistency pulp) provides improved lamellar dislocation in the fiber cell walls, resulting in improved absorption of molecular-level chemicals (such as urea) in the mixture or pulp. An initial solids content of at least 50 wt% of the mixture ensures effective cellulose treatment, i.e., the cellulose walls are subjected to sufficient shear force to effectively break down the cell walls and increase the affinity of solvents and chemicals for cellulose fibrils. An initial solids content of less than 50% by weight, such as less than about 45% by weight, results in lower cellulose processing efficiency. Therefore, when adding urea, a solids content of 50 to 75 wt% is advantageous.

[0050] In the embodiment, it is preferable that the solid content does not exceed 90% of the weight of the mixture, and more preferably does not exceed 75% of the weight of the mixture. Maintaining a high-consistency pulp in which the solid content does not exceed 90% of the weight of the mixture, and more preferably does not exceed 75% of the weight of the mixture, ensures that keratinization or recrystallization due to deactivation caused by the loss of free hydroxyl groups does not occur, and thus prevents the cell wall structure from closing off the absorption of chemicals.

[0051] Within the above constraints, the space is sufficient to allow shear force to act on cellulose without tearing the fibrils from the cellulose surface, and to increase the affinity of the fibrils on the cell walls for solvents and chemicals, which is optimal. A mixture with the above-mentioned solid content is optimal for, for example, cotton, because the six-layer fibril structure does not become saturated with such solid content. When cotton becomes saturated, the fibril structure is locked, and it becomes even more difficult to break the fibril structure, thus increasing the affinity of the cellulose fibers.

[0052] Cellulose can be derived from various sources and in various pulp forms. In one embodiment, cellulose is selected from the group consisting of chemimechanical pulp, mechanical pulp, thermomechanical pulp, chemimechanical pulp and mixtures thereof.

[0053] In a further embodiment, the chemical pulp is selected from the group consisting of organic solvent pulp, sodium alkali pulp, dissolving pulp, kraft pulp, sulfite pulp, hot water extraction pulp, and mixtures thereof. In the embodiment, paper-grade pulp is used. In a further embodiment, dissolving pulp is used. Recycled pulp (such as deinked pulp) may also be used in the embodiment. In a particular embodiment, the cellulose is dried dissolving pulp.

[0054] The source of the raw materials may be virgin chemical pulp or dissolving pulp, or recycled raw materials, such as recycled paper and / or paperboard containing chemical pulp or dissolving pulp.

[0055] Natural plant fibers, either in their virgin form or in the form of chemical pulp or solvent-grade pulp, are also used as raw materials. The sources of natural plant fibers can be their virgin form, or textiles containing natural plant fibers or textiles 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 flax; leaf fibers, such as Manila hemp, jute, pineapple, and banana; and fruit fibers, such as coconut fiber.

[0056] In one embodiment, cellulose is obtained from recycled cellulose selected from the group consisting of paper, paperboard, cotton, cotton linters, wheat straw, rice straw, corn stalks, hemp, kenaf, bagasse, bamboo, flax, jute, and mixtures thereof. This embodiment of the method is particularly effective in pretreating such demanding pulps having multiple fibrillary layers (such as cotton, cotton linters, hemp, flax, linen, and other stem and seed fibers). Cellulose can also be obtained from polyester cotton blends, thereby separating the cellulose component from the non-cellulose component before cellulose pretreatment.

[0057] Similarly, the original source of cellulose also applies. Thus, in one embodiment, cellulose is obtained from native cotton, native cotton linters, native wheat straw, native rice straw, native corn stalks, native hemp, native kenaf, native sugarcane bagasse, native bamboo, native flax, native jute, and mixtures thereof.

[0058] After pretreatment and carbamate esterification to provide cellulose carbamate, in one embodiment, the carbamate is dissolved in an aqueous alkaline medium of the spinning solution to provide a cellulose carbamate spinning solution. In one embodiment, the cellulose carbamate is dissolved in an aqueous alkaline solution prepared with sodium hydroxide and zinc (e.g., zinc oxide and / or zinc hydroxide). The addition of zinc has been shown to improve the solubility of cellulose carbamate and improve the stability of the cellulose carbamate solution. The alkaline solution is prepared from sodium hydroxide and zinc, thereby forming a zincate. Therefore, in the embodiment, the alkaline solution contains sodium zincate.

[0059] According to one embodiment, a method for producing cellulose carbamate filaments or fibers is provided, the method comprising the steps of: providing a cellulose carbamate spinning solution containing cellulose carbamate dissolved in aqueous sodium hydroxide, the spinning solution further comprising a dissolved zinc compound, and feeding the spinning solution into a coagulation unit.

[0060] According to a specific embodiment, the cellulose carbamate spinning solution comprises: - 6 to 10 wt-%, preferably 8 to 10 wt-%, of cellulose carbamate (CCA), - 5 to 10 wt-%, preferably 5 to 7 wt-%, of sodium hydroxide (NaOH), - 0.1 to 2 wt-%, preferably 0.1 to 1.5 wt-%, of zinc oxide (ZnO), - as needed processing aids and / or other additives, the weight percentage (wt-%) being calculated from the total weight of the cellulose carbamate spinning solution. As mentioned above, zinc in forms other than zinc oxide may be used, and the zinc content is 0.08 to 1.6 wt-%.

[0061] Therefore, the embodiment relates to cellulose carbamate fibers, wherein the cellulose carbamate has an average degree of polymerization (DP) of 180 to 500, preferably 200 to 500, and particularly 230 to 350. The degree of polymerization corresponds to intrinsic viscosity of 146 to 368 ml / g, 161 to 368 ml / g, and 182 to 267 ml / g, respectively, which is based on CED viscosity measurement according to ISO 5351:2010 (by dissolving the cellulose carbamate according to the standard method, measuring the polar viscosity of cellulose, and calculating the degree of polymerization). DP is calculated using the following formula: DP 0.905 = 0.75 [η], where 0.905 and 0.75 are characteristic constants of the cellulose-solvent system and [η] is the intrinsic viscosity (ml / g). In order to have a cellulose carbamate suitable for wet spinning of fibers, the degree of polymerization of the cellulose carbamate is preferably reduced from conventional values ​​to the range described herein. The cellulose carbamate of the embodiment has a nitrogen content of 0.3 to 3.0% by weight of cellulose carbamate (measured according to SFS 5505:1988 as described above).

[0062] Carbamate groups are stable under slightly alkaline, neutral, and acidic conditions (e.g., under acidic spinning and stretching conditions). Carbamate groups are hydrolyzed under concentrated alkaline conditions (e.g., dissolved cellulose carbamate is hydrolyzed in an alkaline aqueous solution containing at least, for example, 6.5% NaOH by weight of the spinning solution). Cellulose carbamate begins hydrolysis immediately after dissolution under alkaline conditions to prepare the spinning solution. The higher the temperature of the spinning solution and the longer the delay time between dissolution and solidification, the higher 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 hydrolysis rate determines the degree of substitution of cellulose carbamate. Different spinning baths (e.g., alkaline versus acidic spinning baths in wet spinning processes), subsequent stretching steps, further washing, different finishing processes, and further post-treatment processes can be used to produce fibers with better or more suitable properties. Those skilled in the art can easily determine suitable conditions based on this specification and the following embodiments.

[0063] The post-treatment process may, as needed, include one or more of the following steps: a) post-hydrolysis of carbamate groups with a hot alkaline solution (e.g., cellulose carbamate fibers with a nitrogen content of 0.8 wt% that have been coagulated in an alkaline coagulation bath and stretched by alkaline stretching are subjected to post-hydrolysis in the post-treatment process by treating the fibers at 95 degrees Celsius with a post-hydrolysis solution containing Na₂CO₃ and NaOH for 3 min, resulting in fibers with a nitrogen content of 0.17 wt%), b) acidic and / or neutral and / or alkaline bleaching steps, and / or c) spinning finishing. Carbamate groups are stable in acidic systems and hydrolyzed in alkaline baths. Therefore, fiber properties can be manipulated during coagulation, stretching, further washing, and further post-treatment regeneration, depending on the alkalinity, temperature, and residence time of each step. In particular, these post-treatment conditions are selected to adjust the hydrolysis rate of cellulose carbamates and to use regulated stretching. Cellulose filament bundles are drawn in the first spinning bath or directly after the first spinning bath to improve the final initial modulus and toughness of the fibers. The shape of the fibers can be controlled by adjusting the degree of substitution of the cellulose carbamate entering the spinning and drawing conditions. For example, slightly rounded oval, bean-shaped, or leaf-shaped fibers can be obtained by controlled spinning and drawing of cellulose carbamate containing controlled nitrogen, resulting in a smooth surface.

[0064] In one embodiment, a cellulose carbamate spinning solution is fed into a spinning unit containing an aqueous spinning bath containing sulfuric acid and dissolved aluminum compounds. The cellulose carbamate spinning solution is preferably fed into the spinning unit through one or more spinning nozzles. The spinning solution is fed into the spinning unit at a suitable flow rate. According to one embodiment, once the cellulose carbamate spinning solution is fed into the spinning unit, sulfuric acid reacts with sodium hydroxide and zinc dissolved in the sodium hydroxide to form sodium sulfate, zinc sulfate, and water, thereby causing the spinning bath to contain sulfuric acid, zinc sulfate, aluminum sulfate, sodium sulfate, and water. The cellulose carbamate is coagulated and simultaneously extruded through the spinning nozzles to form filaments.

[0065] In a spinning bath, cellulose carbamate is preferably coagulated into cellulose carbamate filaments through one or more spinning nozzles. These filaments can be recovered from the spinning bath and subjected to stretching, cutting into fibers as needed, and post-processing as needed, wherein the filaments or fibers are washed, bleached, and / or spun finishing.

[0066] According to one embodiment, the stretching bath is a hot stretching bath, in which the filament or filament bundle is immersed in the stretching bath solution. The temperature in the stretching bath is typically in the range of 75 to 100°C, preferably 85 to 95°C, and more preferably about 90°C. The stretching bath may be the same as the spinning bath.

[0067] The method may also include a cutting step after the stretching step, thereby cutting the stretched filament or filament bundle.

[0068] After stretching and, if necessary, cutting, the filaments or fibers can be post-treated in a post-treatment unit. According to a preferred embodiment, post-treatment includes washing, post-hydrolysis as needed, bleaching, spinning finishing, or any combination thereof. In one embodiment, if washing is performed, it is done using water or the effluent from the aforementioned or subsequent processing steps in a countercurrent washing manner. In a preferred embodiment, the post-treatment unit operates based on a countercurrent principle.

[0069] Finally, the obtained filaments or fibers are dried using any known drying method.

[0070] As described 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 to 2.99 wt%, particularly less than 2 wt%, of sodium hydroxide, such as 1.0 to 1.99 wt%.

[0071] In a further embodiment, the dissolved cellulose carbamate is spun in an alkaline spinning bath containing sodium hydroxide and sodium carbonate in a weight ratio of 1:9 to 1:30 (i.e., wt%). Preferably, the spinning bath (coagulation bath) has a pH of more than 7.0, and particularly at least 10.

[0072] Fibers with improved properties can be manufactured using various spinning baths and finishing processes. Carbamate groups are stable in acidic systems and hydrolyzed in alkaline baths. Therefore, in one embodiment, fiber properties can be manipulated during regeneration, especially by using conditioned stretching and / or conditioned post-treatment, since the regeneration of carbamate cellulose occurs during coagulation, stretching, and / or post-treatment.

[0073] The dissolved cellulose carbamate is subjected to wet spinning, while the filament or filament bundle is stretched in a stretching unit. The stretching bath is a hot bath at a temperature of 75 to 100°C. In a suitable embodiment, the filament or filament bundle is stretched in the stretching unit by at least 70% of its length, preferably greater than or equal to 90% of its length, particularly greater than or equal to 95% of its length, or typically 70 to 120% of its length, preferably 90 to 120% of its length. Thus, according to one embodiment, in the stretching unit, the total stretch after the filament solidifies is greater than or equal to 90% of its length, particularly greater than or equal to 95% of its length, or typically 70 to 120% of its length, preferably 90 to 120%. The elongation by length refers to the total elongation between guide discs by adjusting the tensile stress of the filament or filament bundle between rotating rollers at different circumferential speeds (e.g., 25 m / min for the first roller and 50 m / min for the last roller). Therefore, the resulting elongation between guide discs is 100% by length. When the stretching bath temperature is between 75 and 100°C, such high levels of elongation help to provide articles with high initial modulus.

[0074] When cellulose carbamate is dissolved, the carbamate begins to hydrolyze, and some carbamate groups are hydrolyzed during the dissolution, filtration, and degassing of the spinning solution. In one embodiment, the nitrogen content of the cellulose carbamate can be adjusted by changing the dissolution conditions, such as time, temperature, and / or sodium hydroxide concentration. The nitrogen content of the wet spinning of cellulose carbamate is adjusted to produce textile-quality fibers. When coagulation occurs in an acidic spinning bath, carbamate hydrolysis is stopped. When spinning in an alkaline coagulation bath, cellulose regeneration occurs gradually during the coagulation and stretching of the filament bundle. In one embodiment, denitrification can continue during the filament formation period. Spinning parameters and stretching affect the fiber orientation, crystallinity, and final shape of the fabric fibers, and thus affect the mechanical properties of the fibers. In a further embodiment, the nitrogen content of the final product can be adjusted during the washing and post-treatment stages, where most of the remaining carbamate groups can be removed (hydrolyzed), particularly in the alkaline washing step. In a preferred embodiment, the nitrogen content of the final product is in the range of 0.10 to 1.2 wt% based on the dry weight of the fiber, preferably 0.15 to 1.0 wt%, and particularly 0.2 to 0.9 wt%. This corresponds to a degree of substitution (DS) range of 0.012 to 0.144 for cellulose carbamate.

[0075] If improved wet properties, such as low wet elongation and high wet toughness, are desired, it is advantageous to have a low nitrogen content in the final product. In one embodiment, the nitrogen content in the final product is in the range of 0.10 to 0.75 wt%, which corresponds to a degree of substitution of cellulose of 0.012 to 0.09.

[0076] Cellulose fabric fibers are biodegradable. Even if replaced, cellulose carbamate is also biodegradable.

[0077] The coloring rate of cellulose carbamate fibers is very high, and the coloring rate may also be affected by the final nitrogen content.

[0078] In an acidic spinning bath, in addition to controlled stretching, the fiber shape can also be controlled by the amount of aluminum (sulfate) in the spinning bath. This allows for the formation of regular fibers with a controlled amount of aluminum. In one embodiment, the aluminum sulfate concentration in the acidic spinning bath is 90 g / L or higher, preferably 90 to 120 g / L. Aluminum is important because it improves the quality of the produced fibers. Besides controlled stretching, the fiber shape can also be controlled, in particular, by the amount of aluminum (sulfate) in the spinning bath. Aluminum, especially, affects the cross-sectional shape of the fibers. Furthermore, aluminum inhibits cellulose crystallization during the coagulation process. Amphoteric aluminum compounds affect the acid-base neutralization reaction during the coagulation process. This also improves the toughness gains of the recycled fibers.

[0079] For the purposes of implementation: - The elongation ratio is the ratio between the take-up roller and the extrusion rate, and - The elongation ratio is Dr = v, take-up / v, extrusion, where v is the speed, i.e., the speed at which the spinneret enters and exits. Spinneret elongation ratio (Dr) = where a = 1.1150 (1 + fiber moisture % / (100 + fiber moisture %), fiber moisture % = expected to be 13.0% b = 1.1350 (1 + fiber shrinkage % / 100), fiber shrinkage % = expected to be 13.5% ρ = density of spinning solution at feed temperature (kg / m 3) α = cellulose carbamate content of spinning solution (wt-%) = spinneret orifice diameter (µm) DTEX = linear density of filament (dtex) Ω = total inter-guide-disc elongation (%) measured between the first and last guide discs.

[0080] The main purpose of filament stretching is to produce filaments with desired strength by inducing sufficient orientation of polymer molecules along the axial direction. High cellulose molecule orientation tends to increase fiber modulus and toughness. It has been surprisingly found that spinning in an acidic spinning bath is preferably carried out at a nozzle stretch ratio in the range of 0.3 to 1.0, more preferably 0.4 to 0.9, and particularly 0.5 to 0.8. When the fibers of the present invention are spun in an alkaline spinning bath, the optimal range of the nozzle stretch ratio (Dr) is slightly different, i.e., close to 1, such as 0.5 to 1.4, more preferably 0.8 to 1.2.

[0081] Stretching under controlled process conditions can adjust the properties of cellulose fibers. The cross-sectional shape of the fiber can be modified by stretching under controlled process conditions. For example, a slightly rounded / elliptical, bean-shaped or leaf-shaped cross-section of the fiber can be obtained due to a controlled stretching rate, producing a smooth surface with a cotton-like feel.

[0082] Compared to viscous fibers with irregular serrated surfaces, the fibers used as examples are more uniform and smooth in both their surface and internal structure (i.e., cross-section), see, for example, Figure 7. The circular structure of elliptical, bean-shaped, or leaf-shaped fibers provides a high initial modulus.

[0083] Furthermore, compared to viscous fibers with low wet breaking toughness, the relative wet strength (i.e., breaking toughness) of the cellulose fabric fibers of the present invention is improved. In particular, the relative wet elongation of the cellulose fabric fibers of the present invention is very good. In one embodiment, the cellulose fabric fibers, in a conditioned state, have a wet breaking elongation of 85 to 110%, preferably less than 100%, such as 85 to 99.9%, particularly 90 to 99.9% (wet / dry relative %), and a wet strength of at least 0.9 cN / dtex, preferably greater than or equal to 1.0 cN / dtex, and a relative wet strength of 40 to 80% (wet toughness / dry toughness), preferably 45 to 80%. (Relative means wet breaking elongation / dry breaking elongation compared to the typical wet / dry breaking elongation of about 120% for viscous fibers).

[0084] In the cellulose fabric fibers according to the embodiment, there is no or substantially no residual sulfur, especially when an alkaline spinning bath is used.

[0085] Further embodiments relate to the cellulose fabric fibers obtainable by the embodiments of this method, the uses of the fibers obtainable by the embodiments of this method, and the uses of the cellulose fabric fibers. Therefore, one embodiment provides cellulose fabric fibers obtainable by the embodiments of the method described above.

[0086] In a further embodiment, the cellulose fabric fibers of any of the above embodiments are used in yarns, textiles, woven fabrics, knitted fabrics, woven garments or nonwoven items, such as woven yarn bundles, wool bundles, filament yarns or filament bundles.

[0087] Further embodiments relate to articles comprising the cellulose fabric fibers described above. In one embodiment, the yarn comprises the cellulose fabric fibers as described above. In a further embodiment, the textile comprises the cellulose fabric fibers as described above. In a particular embodiment, the woven or knitted fabric comprises the cellulose fabric fibers as described above. In a suitable embodiment, the nonwoven article comprises the cellulose fabric fibers as described above. In a further embodiment, the cellulose fibers in the yarn, textile, or woven fabric are combined with cotton fibers, particularly with virgin cotton fibers. Therefore, by means of the embodiments, it is possible to replace at least a portion of the cotton fibers, particularly virgin cotton fibers, with synthetic cellulose fibers, thereby reducing, for example, the environmental impact of the textile industry. The synthetic cellulose fibers of the above embodiments have an initial modulus similar to cotton fibers, which allows for the replacement of cotton with the synthetic fibers of the present invention.

[0088] Furthermore, it has been surprisingly discovered that the presence of the aforementioned cellulose textiles can be determined by fluorescence detection. Therefore, this embodiment provides a method for determining the presence of cellulose carbamate fibers or articles containing such fibers.

[0089] In one embodiment, the method includes subjecting the article to UV light preferably at 365 nm and detecting fluorescence induced by the cellulose carbamate fiber at wavelengths in the range of 400 to 520 nm. In one embodiment, the article is a yarn, filament bundle, staple fiber, chopped fiber, or wool bundle. In a further embodiment, the article is a fabric garment containing such fibers, such as a bleached and / or dyed article. According to the foregoing, in one embodiment, if the cellulose carbamate has been mixed with viscose fiber, lyocell, or modal in the fiber, filament, yarn, or fabric, the cellulose carbamate present in the man-made cellulose fiber mixture can be detected by fluorescence because other regenerated fibers do not emit fluorescence.

[0090] Fluorescence is light emitted by a substance that absorbs light or other electromagnetic radiation. Cellulose fabric fibers according to the embodiment exhibit fluorescence. Light emitted by fluorescent materials typically has a relatively long wavelength. Cellulose fabric fibers according to the embodiment emit blue / turquoise light, for example, at wavelengths in the range of 450 to 490 nm, which can be observed with the naked eye when the fiber is exposed to UV light, particularly UV light at a wavelength of 365 nm. The fluorescence emission wavelength depends on the excitation wavelength. When the fiber according to the embodiment is excited with UV light, particularly at 365 nm, it exhibits fluorescence (blue) at wavelengths in the range of 420 to 520 nm, and when excited at 546 nm, it exhibits fluorescence (red) at wavelengths in the range of 600 to 750 nm.

[0091] Next, some embodiments will be illustrated by the following examples. Example 1: Chemical pretreatment and carbamate esterification

[0092] Recycled, mixed-color cotton textile waste containing 4.0 ± 2.8 wt% of non-cellulose fibers (mainly polyester, but also trace amounts of nylon, isoprene-containing materials (elastic bandages), polyethylene / polypropylene) with a CED viscosity of 800 ± 200 ml / g (ISO 5351:2010) is mechanically shredded to break down the fabric structure into fragments of fibers with a length of 6 mm. The shredded material is chemically pretreated using a two-stage cooking process and bleaching: in the first acidic stage, the material is treated with sulfuric acid. In the second alkaline stage, the acid-treated material is chemically pretreated with sodium hydroxide to hydrolyze most of the polyester. The average yield through the alkaline stage is based on 92% solids of the material after oven drying. In the bleaching stage, which includes both ozone and alkaline hydrogen peroxide bleaching stages, the degree of polymerization and polydispersity of cellulose are further adjusted. The material obtained from the bleaching process was appropriately dehydrated and used in the subsequent carbamate esterification process. The carbamate esterification process was carried out as described in Finnish Patents FI 112869, FI 112795 and Finnish Patent Application FI 20195717. During the carbamate esterification stage, the degree of polymerization and degree of substitution (carbamate esterification level) of cellulose were adjusted. The viscosity of the chemically pretreated cellulose carbamate material was between 195 and 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 in these examples had a nitrogen content between 1.6% and 1.9% by weight of the cellulose carbamate (measured using SFS 5505:1988). Example 2: Wet spinning of cellulose carbamate spinning solution in an acidic spinning bath.

[0093] The cellulose carbamate obtained from the carbamate esterification process is further dissolved for use in the production of cellulose carbamate fibers by a wet spinning process: the milled and air-dried cellulose carbamate powder is liquefied and dissolved in a sodium zincate (zinc oxane) solution (zinc content is 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 a sodium hydroxide content of 6.5 wt-%. The cellulose carbamate spinning solution obtained from the dissolution process is then filtered using a two-stage backwash filtration process, with a 20 μm filter medium used in the second filtration stage. The wet spinning of the filtered and degassed cellulose carbamate spinning solution is carried out using an acidic spinning bath optimized for the cellulose carbamate process, which contains, for example, sodium sulfate, free sulfuric acid, and aluminum sulfate at 80 g / L or 92 g / L. The cellulose spinning solution was coagulated in a spinning bath and stretched in a hot bath. The elongation ratios used were 0.58 for sample 1, 0.72 for samples 2 and 3, and 0.96 for sample 4. A spinner with an elongation ratio of 1.07 was used as a comparative example for testing. It is worth noting that the fiber does not have sufficient strength to withstand the required stretching to achieve the target fiber properties, with a linear density of < 2.0 dtex.

[0094] The self-spun filament bundles were cut into short fibers with a cut length of 40 mm, except for sample 4 used as the filament. The linear density (dtex) of the fibers was measured according to ISO 1973:2021, and the fiber toughness (cN / dtex), elongation (%), and initial modulus (cN / dtex) of the fibers were measured according to ISO 5079:2020. The dried fibers were conditioned at a relative humidity of 65 ± 2% and a temperature of 20 ± 2°C for at least 24 h. The test speed was 20 mm / min and the gauge length was 20 mm. The average value of 20 measurements (in Favigraph, Textechno) was calculated. When the aluminum sulfate concentration in the spinning bath was 80 g / l, the sample did not have sufficient stability for conditioned tensile testing, and solidified too quickly to form serrated fibers, which did not have sufficient strength to meet the requirements of fabric fibers, see Figure 4. A relatively high amount of aluminum sulfate (92 g / L) was used in successful operations, for samples 1 to 4. Fiber properties are listed in Table 1, for samples 1 to 4. Typical viscose fiber, Tencel, Modal, and cotton samples were measured as references. Example 3: Wet spinning of cellulose carbamate spinning solution in an alkaline spinning bath.

[0095] The cellulose carbamate obtained from the carbamate esterification process is further dissolved for use in the production of cellulose carbamate fibers by a wet spinning process: the milled and air-dried cellulose carbamate powder is liquefied and dissolved in a sodium zincate (zinc oxocyclohexane) solution (zinc content is 0.96 wt-%) to achieve a target cellulose carbamate content of 6.5 wt-% (samples 5, 7 and 8) or 8.4 wt-% (samples 6 and 9) and a sodium hydroxide content of 6.5 wt-%. The cellulose carbamate spinning solution obtained from the dissolution process is then filtered using a two-stage backwash filtration process, with a 20 μm filter medium used in the second filtration stage.

[0096] Wet spinning of the filtered and degassed cellulose carbamate spinning solution was carried out using an alkaline spinning bath optimized for the cellulose carbamate process, containing 24 to 27 wt% sodium carbonate and 1.4 wt% sodium hydroxide. The cellulose spinning solution was solidified in the spinning bath, and the tensile stress applied between the guide discs was 101% to 113% ± 7% under hot bath conditions. The high-stretch filament bundles allowed for large-scale yarn manipulation. The elongation ratios used were 0.72 for sample 5, 0.54 for samples 6 and 8, and 0.70 for samples 7 and 9. A spin with an elongation ratio of 1.01 was used as a comparative example (6.9 wt% cellulose carbamate content, elongation 72%, fineness 1, 11). It is noteworthy that the fibers under these conditions did not possess sufficient strength to withstand the required stretch to achieve the target fiber properties. The filament bundles obtained from self-spinning are cut into short fibers with a cutting length of 40 mm.

[0097] The linear density, fiber toughness, elongation, and initial modulus of the short fibers were measured according to ISO 1973:2021 and ISO 5079:2020, as described in Example 2. Fiber properties are listed in Table 1, samples 5 to 9. Samples 8 and 9, as well as the viscous fiber samples, were also measured in a wet stage to study the wet properties of the new fibers, with a wetting time of 120 s. The elongation at break (%) of wet samples 8 and 9 was lower than that in the dry state, with relative wet elongations of 99% and 88%, respectively. Example 4: Wet spinning of cellulose carbamate spinning solution in an alkaline spinning bath.

[0098] A cellulose carbamate with an intrinsic viscosity of less than 225 ml / g obtained from the carbamate esterification process is dissolved for use in the production of cellulose carbamate fibers by a wet spinning process: the milled and air-dried cellulose carbamate powder is slurried and dissolved in a sodium zincate (zinc oxocyclohexane) solution (zinc content is 0.96 wt-%) to achieve a target cellulose carbamate content of at least 8.0 wt-% and a sodium hydroxide content of 6.5 wt-%. The cellulose carbamate spinning solution obtained from the dissolution process is then filtered using a two-stage backwash filtration process, with a 20 μm filter medium used in the second filtration stage.

[0099] The wet spinning of the filtered and degassed cellulose carbamate spinning solution is carried out using an alkaline spinning bath at 45 degrees Celsius, which is optimal for the cellulose carbamate process. This spinning bath contains 25 wt% sodium carbonate and 1.5 wt% sodium hydroxide. The cellulose spinning solution is extruded (50 µm nozzle diameter) into the spinning bath and solidified therein. The tensile stress applied between the guide discs is 81% to 115% at a 90-degree Celsius hot bath. The high-strength filament bundles allow for large-scale yarn manipulation.

[0100] Samples 10 to 13 were prepared using the following process details.

[0101] Sample 10, cellulose carbamate, with an intrinsic viscosity of 187 ml / g, and a cellulose carbamate content of 8.50 wt% in the spinning solution. Tensile stress was 81% and elongation was 1.12.

[0102] Sample 11, cellulose carbamate, with an intrinsic viscosity of 224 ml / g and a cellulose carbamate content of 8.03 wt% in the spinning solution. Tensile stress was 98% and elongation was 1.02.

[0103] Sample 12, cellulose carbamate, intrinsic viscosity of 200 ml / g, cellulose carbamate content of 9.39 wt% in spinning solution. Tensile stress of 115% and elongation of 1.00.

[0104] Sample 13, cellulose carbamate, with an intrinsic viscosity of 209 ml / g, and a cellulose carbamate content of 8.55 wt% in the spinning solution. The tensile stress was 106% and the elongation was 0.93.

[0105] The linear density, fiber toughness, elongation, and initial modulus of the short fibers were measured according to ISO 1973:2021 and ISO 5079:2020, as described in Example 2. Fiber properties are listed in Table 1, Examples 10 to 13. Example 5: Manufacturing nonwoven objects.

[0106] The nonwoven sample was prepared using a 50:50 weight ratio of Sample 1 and standard viscous fibers containing titanium dioxide (marked A in Figures 6 and 7). The fibers in the composite were analyzed using optical microscopy (Zeiss Imager). Cellulose carbamate fibers (CCA, marked B in Figures 6 and 7) were bright and more uniform from the surface, showing fewer streaks in the longitudinal view (see Figure 6). Compared to the serrated viscous fibers, cellulose carbamate fibers were smoother leaf-shaped / bean-shaped fibers (see Figure 7). Example 6: Determination of terephthalic acid content

[0107] The terephthalic acid content in sample 2 (cut length 40 mm) of cellulose carbamate fiber produced as described in Example 2 was measured using a GC / MS (gas chromatography-mass spectrometry) system. The sample was acidified with hydrochloric acid to pH < 3 and dried overnight in an oven. 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 relative to an external calibration standard. The amount of terephthalic acid was 5 mg / kg (cellulose carbamate fiber). Example 7: Determination of terephthalic acid content

[0108] The terephthalic acid content in sample 2 (cut length 40 mm) of cellulose carbamate fiber produced as described in Example 2 was measured using a GC / MS (gas chromatography-mass spectrometry) system. The sample was first refluxed in sodium hydroxide (10 wt%) for 4 hours to hydrolyze the polyethylene terephthalate in the sample. The 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 relative to an external calibration standard. The amount of terephthalic acid was 309 mg / kg (cellulose carbamate fiber).

[0109] Table 1 shows the various strength properties of the man-made cellulose carbamate fabric fibers spun in an acidic bath for samples 1 to 4 and in an alkaline bath for samples 5 to 13, with reference values ​​to other man-made cellulose fiber materials. Some of the samples mentioned in Table 1 were analyzed under a microscope. The results are shown in the accompanying figures.

[0110] Figure 1 illustrates the strain curves of the toughness of man-made cellulose fabric fibers according to at least some embodiments of the present invention; when read at 6% elongation, from top to bottom: Tencel, cotton, Modal, sample 5, sample 3, viscose fiber, sample 7 (wet) and viscose fiber (wet). Toughness in cN / dtex is plotted on the y-axis and elongation in percentage is plotted on the x-axis.

[0111] Figure 2 is an optical micrograph showing fibers according to at least some embodiments of the present invention. The fibers shown in the figure were prepared as described in Example 2, Sample 2.

[0112] Figure 3 is an optical micrograph showing a cross-section of a man-made cellulose fiber according to at least some embodiments of the present invention. The fiber system having a leaf-shaped / bean-shaped cross-section was prepared as described in Example 2, Sample 2.

[0113] Figure 4 is an electron micrograph showing the serrated cross section of the fiber sample.

[0114] Figure 5 is an optical micrograph showing a cross-section of a fiber according to at least some embodiments of the present invention. The fiber having an elliptical cross-section was prepared as described in Example 3, Sample 5.

[0115] Figure 6 is an optical micrograph showing at least some embodiments of the cellulose carbamate fiber according to the present invention, which was prepared as described in Example 3, Sample 1, and has better uniformity and brightness than the reference viscous fiber.

[0116] Figure 7 is an optical micrograph illustrating the structural differences between cross-sections of at least some embodiments of the cellulose carbamate fiber (sample 1) prepared according to the present invention as described in Example 2 and a comparative reference mucilage fiber. In contrast, the cellulose carbamate fiber according to the embodiment is smooth and has a leaf / bean shape, while the reference mucilage fiber has a serrated or jagged shape.

[0117] It should be understood that the embodiments of the present invention disclosed herein are not limited to the specific structures, process steps, or materials disclosed herein, but extend to equivalents that can be recognized by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting.

[0118] Throughout this specification, the reference to an embodiment or a particular feature, structure, or characteristic described with respect to that embodiment is included in at least one embodiment of the invention. Therefore, the phrase "in an embodiment" or "in a particular embodiment" appearing throughout this specification does not necessarily refer to the same embodiment. Where numerical values ​​are mentioned using terms such as, for example, about, or substantially, precise numerical values ​​are also disclosed.

[0119] As used herein, for convenience, a plurality of items, structural elements, constituent elements and / or materials may be presented in a common list. However, such lists should be interpreted as if each member in the list were individually identified as a separate and distinct member. Therefore, without the contrary, individual members of this list should not be interpreted as existing equivalents of any other member of the same list simply because they are presented in a common group. Furthermore, various embodiments and examples of the invention, together with alternatives to their various components, may be referenced herein. It should be understood that such embodiments, examples and alternatives should not be interpreted as existing equivalents of each other, but should be considered as independent and autonomous statements of the invention.

[0120] Furthermore, the aforementioned features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. Numerous specific details, such as examples of length, width, shape, etc., are provided in the following description to provide a thorough understanding of embodiments of the invention. However, those skilled in the art will recognize that the invention may be practiced without these specific details or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations have not been shown or described in detail to avoid obscuring the embodiments of the invention.

[0121] While the foregoing embodiments illustrate the principles of the invention in one or more specific applications, it will be apparent to those skilled in the art that many modifications in form, use, and implementation details can be made without inventiveness and without departing from the principles and concepts of the invention. Accordingly, the invention is not intended to be limited except as set forth in the claims below.

[0122] The verbs "comprising" and "including" are used in this document as open-ended restrictions, neither excluding nor requiring the presence of features not cited. Features cited in the appendix may be freely combined with each other unless otherwise expressly stated. Furthermore, it should be understood that the use of "a (or an)" (i.e., the singular form) throughout this document does not exclude the plural. Industrial Applications At least some embodiments of the invention have been found to have industrial applications in the textile industry for manufacturing synthetic fibers. Fibers having elongation properties similar to cotton can be provided by the technology of the invention. In embodiments of the technology of the invention, fibers with sufficient flexibility for easy use in yarn manufacturing processes are provided. Cellulose fabric fibers, combined as needed with cotton fibers (such as virgin cotton fibers), are generally used in yarns, textiles, woven or knitted fabrics, woven garments, and nonwovens. [Simplified Explanation of the Diagram]

[0012] [Figure 1] depicts the toughness strain curves of reference materials and at least some embodiments of the artificial cellulose fabric fibers according to the present invention.

[0013] [Figure 2] is an optical micrograph showing fibers of at least some embodiments according to the present invention.

[0014] [Figure 3] is an optical micrograph showing a cross section of a man-made cellulose fiber according to at least some embodiments of the present invention.

[0015] [Figure 4] is an electron micrograph showing a cross section of the reference fiber sample.

[0016] [Figure 5] is an electron micrograph showing a cross section of a fiber sample according to at least some embodiments of the present invention.

[0017] [Figure 6] is an optical micrograph comparing the uniformity and brightness of fibers of at least some embodiments of the present invention with reference fibers.

[0018] [Figure 7] is an optical micrograph depicting the structural differences between fibers of at least some embodiments of the present invention and reference fibers.

Claims

1. A man-made cellulose fabric fiber having a linear density of -0.8 to 1.8 dtex, measured according to ISO 1973:2021; a toughness of -2.0 to 2.9 cN / dtex, measured according to ISO 5079:2020; and an initial modulus of -50 to 120 cN / dtex, measured according to ISO 5079:2020; wherein at least 50 wt% of the fabric fiber raw material is cellulose-containing waste and at least 50 wt% of the cellulose-containing waste is fabric waste.

2. The cellulose fabric fiber according to claim 1, wherein the cellulose fabric fiber contains 90 wt% or more cellulose on a dry weight basis.

3. Cellulose fabric fibers according to claim 1 or 2, wherein the raw material for the fabric fibers is 100% fabric waste.

4. The cellulose fabric fiber according to claim 1 or 2, wherein the cellulose fabric fiber is a cellulose carbamate fiber.

5. The cellulose fabric fiber according to claim 1 or 2, wherein the cellulose fabric fiber has a breaking elongation of 7 to 19% and a nitrogen content of 0.10 to 1.2 wt% based on the dry weight of the fiber.

6. Cellulose fabric fibers according to claim 1 or 2, wherein the cellulose fabric fibers have a wet elongation at break of 85 to 110% of the dry elongation at break (wet / dry relative %) in a conditioned state.

7. The cellulose fabric fiber according to claim 1 or 2, having a wet toughness of at least 0.9 cN / dtex and a relative wet toughness of 40 to 80% (wet toughness / dry toughness).

8. Cellulose fabric fibers according to claim 1 or 2, wherein the cellulose fabric fibers exhibit a linear density of -1.1 to 1.5 dtex; a toughness of -2.1 to 2.8 cN / dtex; and an initial modulus of -60 to 120 cN / dtex.

9. A method for manufacturing cellulose fabric fibers, comprising the following steps: - pretreating a cellulose-based material containing at least 50 wt% cellulose-containing waste, wherein at least 50 wt% of the cellulose-containing waste is fabric waste; - performing cellulose carbamate esterification to form cellulose carbamate; - dissolving the cellulose carbamate in an aqueous alkaline medium to form a cellulose carbamate spinning solution; - spinning the cellulose carbamate spinning solution in an aqueous spinning medium to form filaments or filament bundles, wherein the filaments or filament bundles are subjected to a stretch of at least 70% by length at a temperature of 75 to 100°C in a stretch bath; to obtain cellulose carbamate fibers having a linear density of 0.8 to 1.8 dtex, measured according to ISO 1973:2021; and a toughness of 2.0 to 2.9 cN / dtex, measured according to ISO 1973:2021. Measurements according to ISO 5079:2020; and initial modulus of 50 to 120 cN / dtex, which are measured according to ISO 5079:2020.

10. The method according to claim 9, wherein the pretreated cellulose material, the cellulose carbamate, the dissolved cellulose carbamate, or the cellulose carbamate fiber is modified by chemical treatment.

11. The method according to claim 9 or 10, wherein the pretreatment of the cellulose material is by mechanically processing it to a predetermined particle size, and then subjecting the mechanically processed material to acidic and alkaline treatments in a cooking liquor in a desired order.

12. The method according to claim 9 or 10, wherein the aqueous alkaline medium of the spinning solution is an alkaline solution containing sodium hydroxide and zinc.

13. The method according to claim 9 or 10, wherein the aqueous spinning medium is an alkaline spinning bath.

14. The method according to claim 13, wherein the alkaline spinning bath contains sodium carbonate and less than 3 wt% sodium hydroxide.

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

30.

16. The method according to claim 9 or 10, wherein the aqueous spinning medium is an acidic spinning bath containing aluminum sulfate at a concentration of 90 g / l or higher.

17. The method according to claim 9 or 10, wherein the spinning has a nozzle extension ratio of 0.3 to 1.

0.

18. The method according to claim 9 or 10, wherein in the stretching unit, the total elongation after filament coagulation is greater than or equal to 90% in length.

19. Use of a cellulose fabric fiber according to any one of claims 1 to 8 or a cellulose fabric fiber obtained by any one of claims 9 to 18 in yarn, textiles, woven or knitted fabrics, woven garments or nonwoven fabrics.

20. An article comprising cellulose fabric fibers as defined in any one of claims 1 to 8 or cellulose fabric fibers obtained by any one of claims 9 to 18, wherein the article is yarn, textile, woven or knitted fabric, woven garment or nonwoven fabric.

21. The object according to claim 20, wherein, The cellulose fabric fibers in the object are combined with cotton fibers, and the object is yarn, textile, woven or knitted fabric, or garment.

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