Paper yarn and paper yarn manufacturing method

Abstract

To provide a paper yarn that is excellent in abrasion resistance in wet state and hard to be torn, and allows acquisition of a woven or knitted fabric causing less shape change after being washed with water.SOLUTION: Fine cellulose fibers are adsorbed to a paper yarn.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a paper yarn and a method for producing the paper yarn. [Background technology]

[0002] In recent years, woven and knitted fabrics made from natural fibers derived from plant-based materials, instead of petroleum-derived chemical fibers, have been attracting attention as being sustainable because they are biodegradable and do not cause marine or environmental pollution when washed or disposed of.

[0003] As a woven or knitted fabric using natural fibers made from plant-derived raw materials, there have been known woven or knitted fabrics using paper yarn (also called "twisted yarn") obtained by twisting paper slit tape or paper slit yarn (for example, Patent Document 1, etc.). Paper yarn is made from paper and is mainly composed of cellulose, so it has moisture absorption properties similar to cotton, feels good to the touch, and is lighter than cotton, making it suitable for use in clothing and the like.

[0004] Patent Document 1 describes that in order to give the paper yarn elasticity (stretchability), it contains a core yarn, a covering yarn, and a holding yarn, and that the core yarn contains an elastic yarn that shrinks highly in hot water, and the covering yarn is a paper slit yarn. It also describes that when a woven fabric obtained using this paper yarn was sewn into pants and worn, the pants were stretchy and moisture-absorbent, making them comfortable to wear as summer clothing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-140488 Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, woven and knitted fabrics using paper yarn have problems such as being easily worn when wet, breaking when stretched, and being prone to stretching and wrinkling when washed in water.

[0007] Therefore, the object of the present invention is to provide a paper yarn that can be used to obtain woven or knitted fabrics that have excellent abrasion resistance in a wet state, are resistant to tearing, and undergo little change in shape after washing in water, and a method for producing this paper yarn. [Means for solving the problem]

[0008] As a result of extensive research into achieving this object, the present inventors have discovered that it is extremely effective to adsorb specific fine fibers onto paper yarn, and have completed the present invention.

[0009] The present invention provides the following: (1) Paper yarn with fine cellulose fibers adsorbed. (2) The paper yarn according to (1), wherein the fine cellulose fibers are anion-modified fine cellulose fibers. (3) A method for producing paper yarn, comprising the following steps: Process A: Treating paper thread with caustic Process B: The process of adsorbing fine cellulose fibers onto paper threads (4) The method for producing paper yarn according to (3), wherein the step B is carried out after the step A. (5) The method for producing paper yarn according to (3) or (4), wherein the fine cellulose fibers are anion-modified fine cellulose fibers. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a paper yarn that can be used to obtain woven or knitted fabrics that have excellent abrasion resistance in a wet state, are resistant to tearing, and undergo little change in shape after washing in water, and a method for producing this paper yarn. [Brief explanation of the drawings]

[0011] [Figure 1]1 shows the results of observing the surface of the fabrics obtained in Comparative Example 2 and Example 2 after a home washing test (repeated 10 times). DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. In the present invention, "to" includes the extreme values. That is, "X to Y" includes the values ​​X and Y at both ends.

[0013] The present invention is a paper yarn having fine cellulose fibers adsorbed thereon.

[0014] (paper thread) In the present invention, paper thread means thread obtained by cutting paper (mainly Japanese paper) into thin strips and twisting them. Japanese paper is made by filtering raw materials for Japanese paper, which consist of fibers obtained by beating plants suitable for Japanese paper, such as paper mulberry, mitsumata, hemp, coniferous trees, and bamboo grass. The basis weight of Japanese paper is approximately 10 to 30 g / m 2 This range is preferable from the viewpoint of manufacturing technology, but a fabric having a basis weight greater than this range or a fabric having a basis weight less than this range may also be used.

[0015] The paper thread can be obtained, for example, by slitting a roll of base paper into widths of about 0.8 to 10 mm using a slitter or the like, and then twisting the slit paper.

[0016] In the present invention, the woven or knitted fabric means a fabric such as a woven fabric, a knitted fabric, or a nonwoven fabric, and a molded article obtained by sewing or the like from such a fabric.

[0017] In this specification, when the term "paper yarn, etc." is mentioned, it means the above-mentioned paper yarn as well as woven or knitted fabrics containing the paper yarn.

[0018] When producing woven or knitted fabrics using the paper yarn of the present invention, it is preferable that the paper yarn component be contained in a proportion of 1 wt% or more of the total fiber weight, from the viewpoint of obtaining the effects of the present invention. Furthermore, it is more preferable that the paper yarn component be contained in 10 wt% or more, more preferably 30 wt% or more, more preferably 50 wt% or more, and even more preferably 70 wt% or more. When producing woven or knitted fabrics using the paper yarn of the present invention, it is sufficient that the paper yarn of the present invention is used in part thereof. For example, when producing a woven fabric, the paper yarn of the present invention can be used as the warp or weft. It is also possible to produce woven or knitted fabrics using only the paper yarn of the present invention.

[0019] (fine cellulose fiber) The microfibrillated cellulose fibers used in the present invention are fine fibers made from cellulose, and are a general term for cellulose nanofibers (hereinafter sometimes referred to as "CNF") with an average fiber diameter of less than 500 nm and microfibrillated cellulose (hereinafter sometimes referred to as "MFC") with an average fiber diameter of 500 nm or more. The average fiber diameter is a length-weighted average fiber diameter, and can be measured by observing the microfibrillated cellulose fibers using, for example, a fractionator manufactured by Valmet Co., Ltd. or an atomic force microscope (AFM). The average fiber diameter of the microfibrillated cellulose fibers is not particularly limited, but is about 1 nm to 60 μm. The microfibrillated cellulose fibers can be produced by defibrating cellulose.

[0020] (Cellulose nanofiber (CNF)) The average fiber diameter of the CNF that can be used in the present invention is preferably 100 nm or less, more preferably 50 nm or less. The average fiber length is preferably 5 μm or less, more preferably 3 μm or less. The lower limit of the average fiber length is approximately 0.1 μm or more. The average fiber length can be measured by analyzing 200 randomly selected fibers using an atomic force microscope (AFM) when the diameter is less than 20 nm, or a field emission scanning electron microscope (FE-SEM) when the diameter is 20 nm or more, and calculating the average. The average aspect ratio of the CNF that can be used in the present invention is preferably 50 or more. There is no particular upper limit, but it is usually 1000 or less. The average aspect ratio can be calculated using the following formula: Aspect ratio = average fiber length / average fiber diameter

[0021] (Microfibrillated cellulose (MFC)) The average fiber length of the MFC that can be used in the present invention is preferably 5 μm or more, more preferably 200 μm or more. The upper limit of the average fiber length is preferably 2.0 mm or less, more preferably approximately 1.5 mm or less. The average fiber length (length-weighted average fiber length) can be determined by measurement using a fractionator manufactured by Valmet or the like.

[0022] The cellulose raw material is not particularly limited as long as it contains cellulose, and examples thereof include plants (e.g., wood, bamboo, hemp, jute, kenaf, agricultural waste, cloth, pulp (e.g., unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), bleached kraft pulp (BKP), unbleached softwood sulfite pulp (NUSP), bleached softwood sulfite pulp (NBSP), thermomechanical pulp (TMP), recycled pulp, waste paper, etc.), animals (e.g., ascidians), algae, microorganisms (e.g., acetic acid bacteria (Acetobacter)), microbial products, and the like. The cellulose raw material may be any one of these or a combination of two or more types. Preferably, the cellulose raw material is derived from a plant or a microorganism (e.g., cellulose fiber), and more preferably from a plant.

[0023] The number average fiber diameter of the cellulose raw material is not particularly limited, but is about 30 to 60 μm for softwood kraft pulp, which is a common pulp, and about 10 to 30 μm for hardwood kraft pulp. Other pulps that have undergone general refinement have a diameter of about 50 μm. For example, when chips or other pulps several centimeters in size are refined, they are preferably mechanically treated with a disintegrator such as a refiner or beater to be adjusted to about 50 μm.

[0024] The microfibrillated cellulose fibers used in the present invention can be used without particular restrictions, as long as they are dispersible in a dispersion medium such as water, regardless of the production method used to obtain the microfibrillated cellulose fibers from a cellulose raw material. For example, microfibrillated cellulose fibers produced by mechanically defibrating a cellulose raw material, microfibrillated cellulose fibers produced by acid hydrolysis or alkali treatment of a cellulose raw material, and microfibrillated cellulose fibers produced by defibrating chemically modified cellulose obtained by chemically modifying the hydroxyl groups contained in cellulose can be used. Furthermore, microfibrillated cellulose fibers commercially available in powder form or in the form of an aqueous dispersion can be used by adjusting the concentration to the desired level.

[0025] When using fine cellulose fibers obtained by defibrating chemically modified cellulose as the fine cellulose fibers, it is preferable to use anionically modified fine cellulose fibers produced by defibrating a cellulose raw material (anionically modified cellulose) obtained by anionically modifying cellulose among chemical modifications, from the viewpoint of promoting the progress of defibration. It is also possible to use regenerated fine cellulose fibers obtained by defibrating the chemically modified cellulose raw material to obtain chemically modified fine cellulose fibers, and then subjecting these to a regeneration treatment.

[0026] (anion-modified) In the present invention, anionic modification refers to the introduction of anionic groups into cellulose, specifically the introduction of anionic groups into the pyranose ring of cellulose by oxidation or substitution reaction. In the present invention, the oxidation reaction refers to a reaction in which a methylol group or the like on the pyranose ring is directly oxidized to a carboxyl group. In addition, in the present invention, substitution reaction refers to a reaction in which anionic groups are introduced into the pyranose ring by a substitution reaction other than the oxidation.

[0027] Examples of anionic modification include oxidation (carboxylation), carboxymethylation, etherification, and esterification such as phosphate esterification, phosphite esterification, xanthate esterification, and sulfate esterification. Among these, oxidation (carboxylation) and carboxymethylation are more preferred, and oxidation (carboxylation) is particularly preferred. Note that xanthated cellulose (xanthate cellulose) obtained by xanthate esterification can be easily restored to unmodified cellulose by undergoing a regeneration treatment.

[0028] (oxidation) Oxidized (carboxylated) cellulose can be used as anion-modified cellulose. Oxidized cellulose (also called "carboxylated cellulose") can be obtained by oxidizing (carboxylating) the above-mentioned cellulose raw material using a known method. Although not particularly limited, the amount of carboxyl groups is preferably 0.6 to 3.0 mmol / g, more preferably 1.0 to 2.0 mmol / g, based on the bone-dry weight of the anion-modified cellulose. One example of the oxidation (carboxylation) method is a method in which the cellulose raw material is oxidized in water using an oxidizing agent in the presence of an N-oxyl compound and a compound selected from the group consisting of bromides, iodides, and mixtures thereof. This oxidation reaction selectively oxidizes the primary hydroxyl group at the C6 position of the glucopyranose ring on the cellulose surface, leaving aldehyde groups and carboxyl groups (-COOH) or carboxylate groups (-COO) on the surface. ― The cellulose concentration during the reaction is not particularly limited, but is preferably 5% by weight or less.

[0029] An N-oxyl compound refers to a compound capable of generating a nitroxy radical. Any compound that promotes the target oxidation reaction can be used as the N-oxyl compound. Examples include 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and its derivatives (e.g., 4-hydroxyTEMPO). The amount of the N-oxyl compound used is not particularly limited, as long as it is a catalytic amount capable of oxidizing the cellulose raw material. For example, 0.01 to 10 mmol is preferred, 0.01 to 1 mmol is more preferred, and 0.01 to 0.5 mmol is even more preferred, per 1 g of bone-dry cellulose raw material. The concentration of the N-oxyl compound in the reaction system is preferably about 0.1 to 4 mmol / L.

[0030] Bromides are compounds containing bromine, examples of which include alkali metal bromides that can dissociate and ionize in water. Iodides are compounds containing iodine, examples of which include alkali metal iodides. The amount of bromide or iodide used can be selected within a range that can promote the oxidation reaction. The total amount of bromide and iodide is, for example, preferably 0.1 to 100 mmol, more preferably 0.1 to 10 mmol, and even more preferably 0.5 to 5 mmol, per 1 g of bone-dry cellulose raw material. The modification is a modification due to an oxidation reaction.

[0031] Known oxidizing agents can be used, such as halogens, hypohalous acids, halous acids, perhalogen acids or their salts, halogen oxides, and peroxides. Among these, sodium hypochlorite is preferred because it is inexpensive and environmentally friendly. The appropriate amount of oxidizing agent used is, for example, preferably 0.5 to 500 mmol, more preferably 0.5 to 50 mmol, and even more preferably 2.5 to 25 mmol, per 1 g of bone-dry cellulose raw material. Furthermore, for example, 1 to 40 mol is preferred per 1 mol of the N-oxyl compound.

[0032] The oxidation process of cellulose raw materials can proceed efficiently even under relatively mild conditions. Therefore, the reaction temperature is preferably 4 to 40°C, or may be room temperature, about 15 to 30°C. As the reaction proceeds, carboxyl groups are generated in the cellulose, causing the pH of the reaction solution to decrease. To efficiently proceed with the oxidation reaction, it is preferable to add an alkaline solution such as an aqueous sodium hydroxide solution to the reaction system as needed to maintain the pH of the reaction solution at about 9 to 12, preferably about 10 to 11. Water is preferred as the reaction medium because it is easy to handle and does not easily cause side reactions. The reaction time in the oxidation reaction can be appropriately set depending on the degree of oxidation progress and is usually 0.5 to 6 hours, for example, about 0.5 to 4 hours.

[0033] Alternatively, the oxidation reaction may be carried out in two stages. For example, the oxidized cellulose obtained by filtration after the first stage of the reaction can be oxidized again under the same or different reaction conditions, thereby efficiently introducing carboxyl groups into the cellulose raw material without reaction inhibition by salts produced as by-products in the first stage of the reaction.

[0034] Another example of an oxidation (carboxylation) method is a method in which oxidation is performed by ozone treatment. In the present invention, it is preferable to use TEMPO-oxidized cellulose fine fibers obtained by defibrating oxidized cellulose obtained by a method in which cellulose is oxidized with TEMPO (TEMPO oxidation).

[0035] The amount of carboxyl groups contained in oxidized cellulose fine fibers obtained by modifying a cellulose raw material by oxidation, relative to the bone dry weight of the cellulose fine fibers, is preferably 0.6 mmol / g or more, more preferably 0.8 mmol / g or more, and even more preferably 1.0 mmol / g or more. The upper limit is preferably 2.2 mmol / g or less, more preferably 2.0 mmol / g or less, and even more preferably 1.8 mmol / g or less. Therefore, it is preferably 0.6 mmol / g to 2.2 mmol / g, more preferably 0.8 mmol / g to 2.0 mmol / g, and even more preferably 1.0 mmol / g to 1.8 mmol / g.

[0036] The amount of carboxyl groups in the oxidized cellulose can be adjusted by controlling the reaction conditions, such as the amount of oxidizing agent added, reaction time, etc. The amount of carboxyl groups in the oxidized cellulose and the amount of carboxyl groups in the fine fibers are usually the same.

[0037] In the present invention, in the oxidized cellulose obtained by the above process, the carboxyl groups introduced into the cellulose raw material are usually in the form of a salt, such as an alkali metal salt such as a sodium salt. Prior to the defibration step, the alkali metal salt of the oxidized cellulose may be substituted with another cationic salt such as a phosphonium salt, an imidazolinium salt, an ammonium salt, or a sulfonium salt. The substitution can be carried out by a known method.

[0038] (carboxymethylation) Preferred anionic groups include carboxyalkyl groups such as carboxymethyl groups. Carboxyalkylated cellulose may be obtained by known methods, or commercially available products may be used. The degree of carboxyalkyl substitution per anhydroglucose unit of cellulose is preferably less than 0.60. Furthermore, when the anionic group is a carboxymethyl group, the degree of carboxymethyl substitution is preferably less than 0.60. If the degree of substitution is 0.60 or more, crystallinity decreases and the proportion of soluble components increases, resulting in a loss of function as fine fibers. Furthermore, the lower limit of the degree of carboxyalkyl substitution is preferably 0.01 or more. In consideration of operability, the degree of substitution is particularly preferably 0.02 to 0.50, and more preferably 0.10 to 0.30. An example of a method for producing such carboxyalkylated cellulose includes a method comprising the following steps. The modification is a modification by substitution reaction. This will be explained using carboxymethyl cellulose as an example. i) mixing the starting material with a solvent and a mercerizing agent, and subjecting the mixture to mercerization at a reaction temperature of 0 to 70°C, preferably 10 to 60°C, for a reaction time of 15 minutes to 8 hours, preferably 30 minutes to 7 hours; ii) Subsequently, a step of adding a carboxymethylating agent in an amount of 0.05 to 10.0 times the moles per glucose residue, and carrying out an etherification reaction at a reaction temperature of 30 to 90°C, preferably 40 to 80°C, for a reaction time of 30 minutes to 10 hours, preferably 1 hour to 4 hours.

[0039] The above-mentioned cellulose raw material can be used as the starting material. As the solvent, 3 to 20 times by weight of water or a lower alcohol, specifically water, methanol, ethanol, N-propyl alcohol, isopropyl alcohol, N-butanol, isobutanol, tertiary butanol, etc., can be used alone or in combination. When a lower alcohol is mixed, the mixing ratio is 60 to 95% by weight. As the mercerizing agent, 0.5 to 20 times by mole of an alkali metal hydroxide, specifically sodium hydroxide or potassium hydroxide, can be used per anhydrous glucose residue of the starting material.

[0040] As mentioned above, the degree of carboxymethyl substitution per glucose unit of cellulose is less than 0.06, and preferably 0.01 or more and less than 0.60. Introducing carboxymethyl substituents into cellulose causes electrical repulsion between cellulose molecules. Therefore, cellulose with carboxymethyl substituents introduced can be easily defibrated. Note that if the carboxymethyl substituents per glucose unit are less than 0.02, defibration may be insufficient. The degree of substitution in carboxymethylated cellulose and the degree of substitution when converted into fine fibers are usually the same.

[0041] In the present invention, in the carboxyalkylated cellulose obtained by the above process, the carboxyalkyl group introduced into the cellulose raw material is usually in the form of a salt, such as an alkali metal salt such as a sodium salt. Prior to the defibration process, the alkali metal salt of the carboxyalkylated cellulose may be substituted with another cation salt such as a phosphonium salt, an imidazolinium salt, an ammonium salt, or a sulfonium salt. The substitution can be carried out by a known method.

[0042] (esterification) Esterified cellulose can also be used as anion-modified cellulose. Examples of methods include mixing a powder or aqueous solution of phosphoric acid compound A with a cellulose raw material, or adding an aqueous solution of phosphoric acid compound A to a slurry of the cellulose raw material. Examples of phosphoric acid compound A include phosphoric acid, polyphosphoric acid, phosphorous acid, hypophosphorous acid, phosphonic acid, polyphosphonic acid, or esters thereof. These may be in the form of salts. Among the above, compounds containing phosphoric acid groups are preferred because of their low cost, ease of handling, and the ability to introduce phosphoric acid groups into the cellulose of pulp fibers to improve defibration efficiency. Examples of compounds containing phosphoric acid groups include phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium phosphite, potassium phosphite, sodium hypophosphite, potassium hypophosphite, sodium pyrophosphate, sodium metaphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, potassium metaphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium metaphosphate. Phosphate groups can be introduced using one or more of these compounds. Among these, phosphoric acid, sodium salts of phosphoric acid, potassium salts of phosphoric acid, and ammonium salts of phosphoric acid are preferred from the viewpoints of high efficiency of phosphate group introduction, ease of defibration in the defibration step described below, and ease of industrial application. Sodium dihydrogen phosphate and disodium hydrogen phosphate are particularly preferred. Furthermore, it is desirable to use the phosphoric acid compound A as an aqueous solution, as this allows the reaction to proceed uniformly and increases the efficiency of phosphate group introduction. The pH of the aqueous solution of phosphoric acid compound A is preferably 7 or less, as this increases the efficiency of phosphate group introduction, but a pH of 3 to 7 is preferred from the viewpoint of suppressing hydrolysis of pulp fibers.

[0043] The following method can be mentioned as an example of a method for producing phosphated cellulose. A phosphoric acid compound A is added to a suspension of a cellulose raw material having a solids concentration of 0.1 to 10% by weight while stirring, to introduce phosphate groups into the cellulose. When the cellulose raw material is taken as 100 parts by weight, the amount of phosphoric acid compound A added is preferably 0.2 to 500 parts by weight, and more preferably 1 to 400 parts by weight, in terms of the amount of phosphorus element. If the proportion of phosphoric acid compound A is equal to or greater than the lower limit, the yield of cellulose fine fibers can be further improved. However, if the proportion exceeds the upper limit, the effect of improving the yield reaches a plateau, which is not preferable from a cost perspective.

[0044] In addition to the phosphoric acid compound A, a powder or aqueous solution of compound B may be mixed. Compound B is not particularly limited, but is preferably a nitrogen-containing compound exhibiting basicity. "Basicity" here is defined as the color of the aqueous solution exhibiting pink to red in the presence of a phenolphthalein indicator, or the pH of the aqueous solution being greater than 7. The nitrogen-containing compound exhibiting basicity used in the present invention is not particularly limited as long as it exhibits the effects of the present invention, but is preferably a compound having an amino group. Examples include urea, methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, and hexamethylenediamine. Among these, urea is preferred because of its low cost and ease of handling. The amount of compound B added is preferably 2 to 1,000 parts by weight, more preferably 100 to 700 parts by weight, per 100 parts by weight of the solid content of the cellulose raw material. The reaction temperature is preferably 0 to 95°C, more preferably 30 to 90°C. The reaction time is not particularly limited, but is approximately 1 to 600 minutes, more preferably 30 to 480 minutes. When the esterification reaction conditions are within these ranges, it is possible to prevent the cellulose from being excessively esterified and becoming more soluble, resulting in a good yield of phosphated cellulose. After dehydrating the resulting phosphated cellulose suspension, it is preferable to heat-treat it at 100 to 170°C in order to suppress hydrolysis of the cellulose. Furthermore, it is preferable to heat the suspension at 130°C or lower, preferably 110°C or lower, while it contains water, and then, after removing the water, heat-treat it at 100 to 170°C.

[0045] The degree of phosphate substitution per glucose unit of the phosphated cellulose is preferably 0.001 or more and less than 0.40. Introducing phosphate group substituents into cellulose causes electrical repulsion between cellulose molecules. Therefore, cellulose with phosphate groups introduced can be easily defibrated. If the degree of phosphate substitution per glucose unit is less than 0.001, it cannot be sufficiently defibrated. On the other hand, if the degree of phosphate substitution per glucose unit is greater than 0.40, it may swell or dissolve, making it impossible to obtain fine fibers. To efficiently defibrate, the phosphated cellulose raw material obtained above is preferably subjected to a washing treatment, such as boiling and washing with cold water. The modification by these esterifications is a modification by a substitution reaction. The degree of substitution in the phosphated cellulose and the degree of substitution when made into fine fibers are usually the same.

[0046] In the present invention, in the cellulose phosphate obtained by the above process, the phosphate group introduced into the cellulose raw material is usually in the form of a salt, such as an alkali metal salt such as a sodium salt. Prior to the defibration step, the alkali metal salt of the cellulose phosphate may be substituted with another cationic salt such as a phosphonium salt, an imidazolinium salt, an ammonium salt, or a sulfonium salt. The substitution can be carried out by a known method.

[0047] In the present invention, carbon disulfide is added to alkali-treated cellulose to form xanthate groups (-OCSS - Xanthated cellulose into which xanthate groups have been introduced can be used. After the xanthated cellulose is subjected to the defibration treatment described below, it can be subjected to acid treatment or heat treatment to convert the xanthate groups back into hydroxyl groups, and can be used as regenerated fine cellulose fibers.

[0048] (defibration) In the present invention, the device for defibrating the cellulose raw material is not particularly limited. It is preferable to apply a strong shear force to the aqueous dispersion of the cellulose raw material using a device such as a high-speed rotary device, a colloid mill device, a high-pressure device, a roll mill device, or an ultrasonic device.

[0049] The paper yarn of the present invention is thought to have microfibrillated cellulose fibers adsorbed thereto, which limits the volume increase of the paper yarn due to water absorption, thereby suppressing its swelling; the effect of the present invention can also be achieved by a small amount of microfibrillated cellulose fibers adsorbed to the paper yarn. On the other hand, by adsorbing and covering the surface of the fibers with 0.01 wt% or more of microfibrillated cellulose fibers based on the paper yarn, the spacing between the microfibrillated cellulose fibers on the surface of the paper yarn becomes smaller, making it possible to effectively suppress swelling when the paper yarn absorbs water. Furthermore, by adsorbing and covering the paper yarn with microfibrillated cellulose fibers at a rate of 0.05 wt% or 0.1 wt% or more, it becomes possible to significantly improve the swelling property of the paper yarn.

[0050] Furthermore, from the viewpoint of improving the swelling properties of the paper yarn, there is no upper limit to the amount of fine cellulose fibers to be coated, but from the viewpoint of maintaining the texture of the paper yarn coated with fine cellulose fibers, it is desirable to keep the amount of adsorbed fine cellulose fibers to 5 wt% or less based on the paper yarn.

[0051] The surface of the paper yarn to which the fine cellulose fibers of the present invention are adsorbed does not necessarily have to be covered entirely with fine cellulose fibers such as CNF, and when the paper yarn absorbs water, the swelling properties can be improved by having the fine cellulose fibers adsorbed to the surface of the paper yarn to an extent that the increase in volume due to swelling can be suppressed.

[0052] Specifically, from the viewpoint of producing an effect of improving the swelling property of the paper yarn, it is preferable that the fine cellulose fibers are adsorbed and covered over an area of ​​10% or more of the paper yarn surface, and from the viewpoint of producing a significant effect of improving swelling property, it is preferable that the fine cellulose fibers are adsorbed and covered over an area of ​​preferably 30% or more, more preferably 50% or more of the paper yarn surface. Furthermore, from the viewpoint of producing a significant effect of improving swelling property, it is also preferable that the entire surface of the paper yarn is covered by the fine cellulose fibers, and further, that the entire surface of the paper yarn is covered by multi-layered fine cellulose fibers. The fine cellulose fibers adsorbed on the surface of the paper yarn can be observed, for example, using a scanning electron microscope, and it is possible to evaluate the coverage rate of the paper yarn, etc.

[0053] The paper yarn with the fine cellulose fibers of the present invention adsorbed thereon may be processed into a woven or knitted fabric as is, or may be twisted together with a yarn made of a fiber of a material different from that of paper (hereinafter sometimes referred to as "different material yarn") to form a double-twisted yarn, which may then be processed into a woven or knitted fabric.

[0054] Filament yarns (long fibers) and spun yarns can be used as the mixed material yarns. Examples of filament yarns include polyurethane elastic yarns, polyester fibers, polyamide fibers, acrylic fibers, polypropylene fibers, and regenerated cellulose fibers. Examples of spun yarns include natural fibers such as cotton, wool, silk, and hemp, as well as polyester fibers, polyamide fibers, acrylic fibers, polypropylene fibers, and regenerated cellulose fibers.

[0055] Furthermore, water-soluble yarn can be used as the different material yarn. It is desirable that the water-soluble yarn dissolves quickly when immersed in water at a temperature lower than the boiling point. Specifically, when the water-soluble yarn is immersed alone in water at a temperature of 90°C and left for 30 minutes, it is desirable that the water-soluble yarn exhibits a water solubility such that 85% or more by weight of the water-soluble yarn before immersion is dissolved, and more desirable that 95% or more by weight is dissolved. Examples of such water-soluble yarn include water-soluble polyvinyl alcohol fibers, water-soluble ethylene-vinyl alcohol copolymer fibers, and water-soluble polyamide fibers. The water-soluble yarn may be a filament yarn or a spun yarn.

[0056] As the different material yarn, only one or more different material yarns that are not water-soluble may be used, only water-soluble yarns may be used, or a combination of water-soluble yarns and one or more different material yarns that are not water-soluble may be used.

[0057] When knitting or weaving a plied or twisted yarn using only water-soluble yarn as the different material yarn, or when knitting or weaving a plied or twisted yarn using two or more different material yarns and including a water-soluble yarn, the water-soluble yarn is dissolved and removed with water before or after knitting or weaving. In the plied or twisted yarn, the paper yarn is twisted and compressed by the water-soluble yarn, so when the water-soluble yarn is dissolved and removed from the plied or twisted yarn, a force acts on the paper yarn trying to return to its original state from its previously compressed state. Therefore, when the water-soluble yarn is dissolved and removed before knitting or weaving, the stretchability developed in the paper yarn makes knitting and weaving easier, and a woven or knitted fabric with excellent stretchability is produced. On the other hand, when the water-soluble yarn is dissolved and removed after knitting or weaving, a woven or knitted fabric with excellent stretchability is produced, and the voids formed after the water-soluble yarn dissolves result in a woven or knitted fabric with a fluffy texture and high breathability.

[0058] (Method of manufacturing paper yarn adsorbed with fine cellulose fibers) An example of a method for producing paper yarn having microfibrillated cellulose fibers adsorbed thereon according to the present invention is a production method comprising step A: treating paper yarn with caustic, and step B: adsorbing microfibrillated cellulose fibers onto the paper yarn. In this production method, the order of steps A and B does not matter, but it is preferable to perform step B after step A.

[0059] (Process A) Step A is a step in which the paper yarn is treated with caustic. This is generally called mercerization or mercerization, and specifically, it is a step in which the paper yarn or a woven or knitted fabric containing the paper yarn is immersed in an alkaline solution of 5 to 30 Baume, preferably 8 to 30 Baume, at 10 to 60°C, preferably 10 to 40°C. The fabric immersed in the alkaline solution is squeezed with a mangle and stretched in the warp direction for 20 to 120 seconds, after which it is washed with hot water, neutralized by passing it through a neutralizing solution containing an aqueous formic acid solution, and then preferably washed with hot water, rinsed with water, and dried. Examples of alkaline components include sodium hydroxide, lithium hydroxide, and potassium hydroxide.

[0060] (Process B) Step B is a step of adsorbing fine cellulose fibers onto paper yarn. Hereinafter, step B will also be referred to as the "adsorption step."

[0061] The adsorption treatment of the fine cellulose fibers onto the paper yarn can be carried out by a fine cellulose fiber adsorption step in which the paper yarn, etc. is immersed in a fine cellulose fiber dispersion in which the fine cellulose fibers are dispersed at an appropriate ratio to impregnate and adsorb the fine cellulose fibers into the paper yarn, etc., followed by a drying step in which the paper yarn, etc. is dried. Furthermore, after the drying step, the paper yarn, etc., can be subjected to a setting treatment (shape stabilization treatment) at about 150 to 200°C while maintaining the predetermined shape, thereby imparting the initial shape to the paper yarn, etc., with the fine cellulose fibers adsorbed on the surface.

[0062] In the process of adsorbing fine cellulose fibers onto the above-mentioned paper yarn, for example, when the paper yarn is twisted with other yarns to form a ply-twisted yarn, the fine cellulose fibers may be adsorbed onto the paper yarn before it is made into a ply-twisted yarn, or the fine cellulose fibers may be adsorbed onto paper yarn that has been refined or bleached, or the fine cellulose fibers may be adsorbed onto a woven or knitted fabric obtained using the paper yarn.

[0063] Furthermore, the treatment method according to the present invention involves immersing paper yarns or the like in a dispersion liquid in which fine cellulose fibers are dispersed, thereby impregnating and adsorbing the fine cellulose fibers into the paper yarns or the like, and is similar to the dyeing process of textile products, so it can be carried out as part of the dyeing process or the like carried out on textiles or woven or knitted fabrics. In other words, within the scope that does not impair the effects of the present invention, the fine cellulose fibers may be adsorbed onto the textiles or woven or knitted fabrics before or after dyeing in the dyeing process, or the fine cellulose fibers may be mixed with a dye or the like, and the fine cellulose fibers may be adsorbed onto the paper yarns or the like simultaneously with dyeing.

[0064] It is also possible to combine a process using resins that is carried out to impart various properties to paper yarns, etc. with a treatment using the fine cellulose fibers of the present invention. That is, various combinations with processes that use resins are possible, such as carrying out resin processing on paper yarns, etc. that have been subjected to the fine cellulose fiber processing of the present invention, carrying out fine cellulose fiber processing and resin processing simultaneously using a treatment liquid in which a resin component, etc. is mixed with a dispersion liquid containing fine cellulose fibers, and carrying out the fine cellulose fiber processing of the present invention on paper yarns, etc. that have been resin-processed.

[0065] As a means for adsorbing fine cellulose fibers onto paper yarns, etc., it is possible to appropriately use, for example, a means classified as a so-called dip dyeing process in which fibers are immersed in a bath in which a dye is dissolved to allow the fibers to absorb the dye, and the fine cellulose fibers can be easily adsorbed by using a dispersion of fine cellulose fibers as the bath. For example, by dip dyeing high-pressure processing in which paper yarns, etc. are immersed in a dispersion containing fine cellulose fibers, the dispersion is sealed in a container, heated to about 120°C, and maintained under high temperature and high pressure, it is possible to efficiently adsorb the fine cellulose fibers contained in the dispersion onto paper yarns, etc.

[0066] Furthermore, in a padding process or the like which is carried out as a finishing process after dyeing a woven or knitted fabric containing paper yarn, the woven or knitted fabric containing paper yarn may be immersed in a treatment liquid containing fine cellulose fibers to adsorb the fine cellulose fibers, and then the fine cellulose fibers may be adsorbed onto the paper yarn, etc. by dehydrating with a roll, drying, heat treatment (curing) processes, etc.

[0067] Alternatively, the fine cellulose fibers can be adsorbed onto the surface of the paper yarn by simply immersing the paper yarn or the like in a fine cellulose fiber dispersion to adsorb the fine cellulose fibers onto the surface of the fiber, followed by drying or heat treatment, thereby achieving a shape-retaining effect. In addition, the fine cellulose fibers can also be adsorbed onto the surface of the paper yarn by using a spraying method, a coating method, a printing method, etc. Furthermore, by performing a fine cellulose fiber adsorption treatment on woven and knitted fabrics, particularly those containing paper yarn, the fine cellulose fibers are also adsorbed at the intersections of fibers present in the woven and knitted fabric, which is expected to suppress misalignment between fibers and more effectively produce shape retention effects, etc.

[0068] In step B of the present invention, the dispersion medium for dispersing the microfibrillated cellulose fibers can be any appropriate dispersion medium as long as it does not particularly harm the paper yarn, etc., being treated. Microfibrillated cellulose fiber-containing aqueous solutions in which microfibrillated cellulose fibers are dispersed in an aqueous solution are commercially available as dispersions of microfibrillated cellulose fibers, and the treatment according to the present invention can be carried out using an aqueous dispersion of microfibrillated cellulose fibers obtained by appropriately diluting the aqueous solution containing microfibrillated cellulose fibers. On the other hand, it is preferable to carry out the treatment according to the present invention using a dispersion in which microfibrillated cellulose fibers are dispersed in an organic solvent that is less aggressive to paper yarn, etc., such as that used in general dry cleaning, in that swelling of the paper yarn, etc., due to water absorption that occurs during the treatment can be prevented.

[0069] In the treatment method according to the present invention, it is desirable to determine the amount (concentration) of the microfibrillated cellulose fibers in the microfibrillated cellulose fiber dispersion to be used, taking into consideration the amount of microfibrillated cellulose fibers adsorbed on the paper yarn or the like after treatment. When the fine cellulose fibers are adsorbed onto paper yarns or the like by the above-mentioned dip dyeing process, it is possible to adsorb almost the entire amount of the fine cellulose fibers in the fine cellulose fiber dispersion onto the paper yarns or the like, and therefore a treatment liquid can be used in which the amount of fine cellulose fibers dispersed corresponds to the amount of paper yarns or the like to be treated and the target amount of fine cellulose fibers to be adsorbed.

[0070] Furthermore, when paper yarns or the like are immersed in a treatment solution containing fine cellulose fibers under specified conditions and then subjected to a padding process such as dehydration to adsorb the fine cellulose fibers onto the paper yarns or the like, it is desirable to determine the concentration of fine cellulose fibers in the treatment solution so that the desired amount of fine cellulose fibers is adsorbed onto the paper yarns or the like after treatment. For example, by immersing paper yarns in a treatment solution containing about 0.001% or more of fine cellulose fibers, or by padding the paper yarns using the treatment solution, it is possible to reduce the swelling of the paper yarns and inhibit stretching after washing.

[0071] By immersing paper yarns or the like in a dispersion liquid in which fine cellulose fibers are dispersed, the fine cellulose fibers or fibrous aggregates that come into contact with the paper yarns or the like become entangled and adhere to the surface of the fibers, and it is thought that the fine cellulose fibers are well adsorbed to the surface of the paper yarns, mainly because both have the same molecular structure. It is also presumed that the adsorption of the fine cellulose fibers suppresses subsequent changes in shape of the paper yarns due to swelling, etc., and as a result, it is thought that stretching and wrinkles when washed in water, etc. are suppressed.

[0072] In the manufacturing method according to the present invention, the paper yarns adsorbed with microfibrillated cellulose fibers can be further coated with an appropriate resin component depending on the purpose, such as imparting a desired texture or water repellency to the paper yarns. It is also possible to coat the paper yarns with microfibrillated cellulose fibers pre-mixed with a resin component. In particular, coating with a resin component in addition to adsorbing microfibrillated cellulose fibers can improve the tear strength of woven or knitted fabrics containing paper yarns. Suitable resins include crosslinkable cellulose-reactive resins such as urea-formaldehyde resin, nylon resin, polyamide resin, melamine-formaldehyde resin, ethylene urea, triazone resin, propylene urea, glyoxal urea resin, polycarboxylic acid, and epoxy resin, as well as resins effective in improving the stretch recovery of knitted fabrics, such as silicone resin and polyurethane resin.

[0073] The resin components used above, which are primarily intended to hydrophobize the paper yarn surface, include fluorine-based, paraffin wax-based, etc. Furthermore, the use of glyoxal resin, which is generally used to prevent wrinkles and shrinkage of cellulose fibers, is expected to cause a crosslinking reaction between cellulose molecules contained in the fibers and fine cellulose fibers, which is preferable in that it further enhances the effect of the fine cellulose fiber treatment according to the present invention.

[0074] The glyoxal resin may be a low-formaldehyde resin or a non-formaldehyde resin, which is preferable from the standpoint of safety since it generates less formalin.

[0075] When using the resin component as described above, a catalyst can be added to enhance the reactivity of the resin component with cellulose and to rapidly promote the crosslinking reaction. The type of catalyst can be appropriately selected depending on the type of resin component used.

[0076] The microfibrillated cellulose fiber dispersion in which paper yarn or the like is immersed for the purpose of adsorbing the microfibrillated cellulose fibers can be mixed with appropriate chemicals or the like depending on the purpose, such as facilitating the adsorption process by the microfibrillated cellulose fibers. For example, various dispersants can be used to disperse the microfibrillated cellulose fibers well in the microfibrillated cellulose fiber dispersion. Examples of dispersants include various polymers that function as surfactants, orange oil, etc.

[0077] Furthermore, in the case of a microfibrillated cellulose fiber dispersion, it is effective to adjust the acidity depending on the type of fiber to be modified, etc., in order to promote adhesion of the microfibrillated cellulose fibers to the paper yarn. Chemicals that can be used to adjust the acidity include sodium hydroxide and soda ash for alkalizing, and oxalic acid, acetic acid, malic acid, etc. for acidifying.

[0078] In addition to the above-mentioned components, various additives may also be used in the fine cellulose fiber dispersion, as needed, such as a crosslinking agent such as a blocked isocyanate-based crosslinking agent, a softener for adjusting texture, a formalin catcher agent for reducing the concentration of free formalin, a surfactant as a penetrating agent, an inorganic compound as an anti-slip agent, and a processing agent (strength reduction prevention agent) for preventing a decrease in fiber strength due to resin processing.

[0079] The woven or knitted fabric obtained using the paper yarn having the fine cellulose fibers adsorbed thereon according to the present invention has excellent abrasion resistance in a wet state, is resistant to tearing, and shows little change in shape after washing in water. [Example]

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, unless the method for measuring / calculating each value in each example is specifically stated, it was measured / calculated by the method described in the specification.

[0081] (Production Example 1) (Production of oxidized cellulose nanofibers) 5.00 g (bone-dry) of bleached, unbeaten kraft pulp (85% brightness) derived from softwood was added to 500 mL of an aqueous solution containing 39 mg (0.05 mmol per g of bone-dry cellulose) of TEMPO (Sigma-Aldrich) and 514 mg (1.0 mmol per g of bone-dry cellulose) of sodium bromide, and the mixture was stirred until the pulp was uniformly dispersed. Sodium hypochlorite solution was added to the reaction system to adjust the sodium hypochlorite concentration to 6.0 mmol / g, initiating the oxidation reaction. During the reaction, the pH of the system decreased, but was gradually adjusted to 10 by the addition of 3 M sodium hydroxide solution. The reaction was terminated when the sodium hypochlorite was consumed and the pH no longer changed. The reaction mixture was acidified with hydrochloric acid, filtered through a glass filter, and thoroughly washed with water to obtain oxidized pulp (carboxylated cellulose). The pulp yield was 90%, the oxidation reaction took 90 minutes, and the carboxyl group content was 1.6 mmol / g. The mixture was adjusted to 1.0% (w / v) with water and adjusted to pH 7 with 3 M sodium hydroxide solution. The mixture was processed three times in an ultra-high-pressure homogenizer (20 °C, 150 MPa) to obtain a dispersion of TEMPO-oxidized cellulose nanofibers (CNF). The average fiber diameter was 3 nm and the average fiber length was 550 nm. The transparency was 88.9% (solid content 1.0%). Furthermore, the B-type viscosity of this oxidized CNF dispersion at 60 rpm at a solids concentration of 1 wt% was 3260 mPa·s.

[0082] Example 1 A woven fabric (weave density: warp 68 / 2.54 cm, weft 54 / 2.54 cm) (Tosco Corporation, GT5853) was manufactured using paper yarn (apparent count: 31.9) made from Japanese paper (100% Manila hemp) as the warp and weft. The fabric was heat-set at 170°C for 1 minute using a 5-chamber heat-setting machine, then immersed in a 5-baume sodium hydroxide solution at 20°C. After 20 seconds, the fabric was wrung out using a mangle, washed with hot water, neutralized by passing it through a neutralizing solution, and then subjected to a caustic treatment by rinsing with hot water, washing with water, and drying (Step A).

[0083] Next, the caustic-treated fabric was dyed using a reactive dye in a jet dyeing machine at 60°C, and then the microfibrillated cellulose fibers were subjected to an adsorption treatment (Step B). Specifically, to the aqueous dispersion of TEMPO-oxidized cellulose nanofibers (TEMPO-oxidized CNF) produced in Production Example 1 (CNF solids concentration: 1.0 wt%, hereinafter sometimes referred to as the "stock solution"), a dispersant (Alcosol GL, manufactured by Meisei Chemical Industry Co., Ltd.) was added in an amount equivalent to 2 wt% of the stock solution, and the mixture was then diluted with industrial water so that the weight ratio of the CNF solids was 0.02%, to obtain a treatment solution.

[0084] Using a padding treatment device, the caustic-treated and dyed fabric was immersed in the treatment solution for 5 to 6 seconds, then squeezed with a roll to achieve a wet pickup of 100% by weight. After drying, the fabric was set with hot air at 170°C for approximately 60 seconds (shape stabilization treatment) to produce a fabric adsorbed with TEMPO-oxidized CNF as fine cellulose fibers.

[0085] (Comparative Example 1) The woven fabric used in Example 1 before the steps A and B were subjected to a wet abrasion test.

[0086] (evaluation) (Wet abrasion test) The woven fabrics obtained in Example 1 and Comparative Example 1 were subjected to abrasion tests using wet test pieces according to JIS L 1096 E method (Martindale method). The pressure load was 9 kPa. The endpoint was determined as the point at which a change in appearance occurred and thread breakage occurred, and the number of frictions up to the endpoint was counted. The results are shown in Table 1. The greater the number of frictions, the better the abrasion resistance in wet conditions.

[0087] [Table 1]

[0088] As can be seen from Table 1, the fabric of Example 1, which contains paper yarn adsorbed with the fine cellulose fibers of the present invention, has superior abrasion resistance when wet compared to the fabric of Comparative Example 1, which contains paper yarn that has not been treated to adsorb the fine cellulose fibers.

[0089] Example 2 A woven fabric (weave density: 96 warp threads / 2.54 cm, 80 weft threads / 2.54 cm) was produced using a jacquard loom, with cotton yarn (80 / 1 cotton) as the warp and paper yarn (pile count: 1 / 62, manufactured by Tosco Corporation, Glasstone) as the weft. The fabric thus obtained was subjected to steps A and B in the same manner as in Example 1 to produce a fabric adsorbed with TEMPO-oxidized CNF as fine cellulose fibers. The resulting fabric was subjected to various tests.

[0090] (Comparative Example 2) The woven fabric produced in Example 2 before the steps A and B were subjected to various tests.

[0091] (evaluation) (breaking elongation) The fabrics obtained in Example 2 and Comparative Example 2 were subjected to tensile tests in standard (dry) and wet conditions using a constant-rate extension tensile tester according to JIS L 1096 Method A (strip method) and Method C (wet strip method), and the elongation at break (%) was measured. The test specimen width was 25 mm, the grip spacing was 100 mm, and the pulling speed was 100 mm / min. The tensile test was performed in the weft direction. The results are shown in Table 2.

[0092] (Home washing test) The fabrics obtained in Example 2 and Comparative Example 2 were subjected to a home laundering test in accordance with JIS L 1930 C4N. The test was repeated five times, and the length in the weft direction of the measurement section before and after the test was measured to calculate the dimensional change rate. The drying method used was Method C (flat drying). The results are shown in Table 2. Positive values ​​for the dimensional change rate indicate elongation.

[0093] In the above-mentioned home washing test, the washing was repeated 10 times, and the appearance of the woven fabric after the test was visually inspected and the state of wrinkles was evaluated. The evaluation results are shown in Table 2. Photographs of the observation results of the woven fabrics obtained in Comparative Example 2 and Example 2 after 10 repeated home washing tests are shown in Figure 1. In Figure 1, the upper side shows the observation results of the sample of Comparative Example 2, and the lower side shows the observation results of the sample of Example 2.

[0094] [Table 2]

[0095] As can be seen from Table 2, the fabric of Example 2, in which the paper yarn adsorbed with the fine cellulose fibers of the present invention was used as the weft yarn, was less likely to tear when pulled in the direction of the paper yarn (horizontal direction), and showed less stretch in the direction of the paper yarn (horizontal direction) when washed in water, resulting in less change in shape, compared to the fabric of Comparative Example 2, in which untreated paper yarn was used. In addition, the occurrence of wrinkles after washing in water was suppressed (see Figure 1).

Claims

1. Paper thread with fine cellulose fibers adsorbed.

2. The paper yarn according to claim 1, wherein the fine cellulose fibers are anion-modified fine cellulose fibers.

3. A method for producing paper yarn, comprising the following steps: Step A: Treating paper yarn with caustic Step B: A step of adsorbing fine cellulose fibers onto paper yarn

4. The method for producing paper yarn according to claim 3, wherein the step B is carried out after the step A.

5. The method for producing paper yarn according to claim 3 or 4, wherein the fine cellulose fibers are anion-modified fine cellulose fibers.

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