Method for processing regenerated cellulose fibers and processed fibers

Abstract

To provide a dimensionally stabilized regenerated cellulose fiber by reducing an amount of reduction after water wash cleaning, etc.SOLUTION: A fiber includes an adsorbate on a surface of a twist yarn including a basic fiber obtained by spinning a regenerated cellulose raw material. The adsorbate includes a cellulose nanofiber.SELECTED DRAWING: Figure 2A

Description

Technical Field

[0001] The present invention relates to a method for stabilizing the dimensions of regenerated cellulose fibers obtained by spinning regenerated cellulose or the like, regenerated cellulose fibers treated by the treatment method, and woven or knitted fabrics containing the regenerated cellulose fibers.

Background Art

[0002] Regenerated cellulose fibers such as rayon, polynosic, cupra, lyocell, and acetate have unique drapability, texture, luster, and slipperiness peculiar to cellulose filaments. Therefore, in addition to general women's clothing fabrics, stalls, linings for men's and women's clothing, they are used in a wide range of applications such as curtains, craft threads, furoshiki, bags, and footwear. Also, taking advantage of the heat retention and moisture absorption properties exhibited by regenerated cellulose fibers, they are widely used for underwear. In recent years, applications as functional underwear that utilize the exothermic effect of moisture absorption that occurs when moisture is adsorbed on the fiber surface have been expanding.

[0003] On the other hand, in the above-mentioned regenerated cellulose fibers, due to their high hygroscopicity, it is known that they have the characteristic of absorbing water and swelling when immersed in water by washing or the like, and then the fiber length contracts during subsequent drying. For this reason, fabrics made of regenerated cellulose fibers are generally difficult to wash by water, and have the problem that washing is required by dry cleaning.

[0004] The swelling properties and resulting shrinkage of fiber length exhibited by the regenerated cellulose fibers described above are thought to originate from the structure of the fibers, which is a consequence of the manufacturing process from cellulose raw materials. In other words, in the production of regenerated cellulose fibers, natural cellulose raw materials are dissolved in carbon disulfide or copper ammonia solution, and the resulting material is spun. It is known that the crystallinity of natural cellulose decreases during this process. As a result, regenerated cellulose fibers exhibit swelling because moisture easily penetrates between the cellulose molecules that make them up, and it is thought that shrinkage occurs after drying because the cellulose molecules rearrange within the fiber when it swells.

[0005] To address the above problems, various improvement measures have been proposed. For example, Patent Document 1 describes a method for suppressing damage to textiles caused by washing, etc., by applying a long-chain hydrocarbon compound to the surface of regenerated cellulose fibers, etc. Patent Document 2 describes a method for enabling water washing by coating the surface of regenerated cellulose fibers, etc., with amino-modified silicone. On the other hand, Patent Document 3 describes a method for suppressing shrinkage caused by water washing, etc., by applying a predetermined crosslinking agent that reacts with hydroxyl groups in cellulose molecules to regenerated cellulose fibers to form crosslinked structures between and between cellulose molecules, thereby suppressing the rearrangement of cellulose molecules within the fiber. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-6808 [Patent Document 2] Japanese Patent Publication No. 2012-1830 [Patent Document 3] Japanese Patent Publication No. 2005-113333 [Patent Document 4] Japanese Patent Publication No. 2008-1728 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to improve upon the problems of the above-mentioned regenerated cellulose fibers and, in particular, to provide a novel treatment method for reducing shrinkage after washing and stabilizing the dimensions of woven or knitted fabrics containing regenerated cellulose fibers. Furthermore, the invention aims to provide regenerated cellulose fibers treated by this method, and woven or knitted fabrics containing these regenerated cellulose fibers. [Means for solving the problem]

[0008] To solve the above problems, the present invention provides the following means. (1) A fiber having adsorbent material on the surface of a twisted yarn containing raw fibers obtained by spinning regenerated cellulose raw material, wherein the adsorbent material contains cellulose nanofibers. (2) A method for processing fibers, comprising a cellulose nanofiber adsorption step in which fibers containing raw fibers obtained by spinning a regenerated cellulose raw material are immersed in a cellulose nanofiber dispersion in which cellulose nanofibers are dispersed, thereby adsorbing adsorbent material containing cellulose nanofibers, and a drying step in which the fibers on which the adsorbent material containing cellulose nanofibers has been adsorbed are dried. Furthermore, the present invention further includes the following means. (3) The above-mentioned fiber having a weight percentage of cellulose nanofiber of 0.01 wt% or more. (4) The above-mentioned fibers further containing resin in the adsorbent. (5) Woven or knitted fabrics containing the above-mentioned fibers. (6) The above treatment method wherein the cellulose nanofiber dispersion contains a resin component. (7) The above processing method, further comprising a resin adsorption step of immersing the regenerated cellulose fibers in a solution containing resin components after the drying step. (8) The above processing method, wherein the above fibers are processed into a woven or knitted fabric. [Effects of the Invention]

[0009] According to the present invention, the dimensional stability of regenerated cellulose fibers can be improved, and the amount of shrinkage of regenerated cellulose fibers or woven or knitted fabrics containing regenerated cellulose fibers after washing can be reduced. [Brief explanation of the drawing]

[0010] [Figure 1A] This is a photograph showing an example of the state in which CNF has been precipitated from a CNF dispersion. [Figure 1B] This photograph shows an example of the state in which CNF has precipitated from a CNF dispersion after shrinkage prevention treatment of regenerated cellulose fibers. [Figure 2A] This is a SEM image of cupro fiber with adsorbed CNF. [Figure 2B] This is a SEM image of cupro fiber. [Modes for carrying out the invention]

[0011] The present invention is preferably applied to fibers known as regenerated cellulose fibers. In the present invention, regenerated cellulose refers to cellulose and cellulose derivatives that exhibit higher hygroscopicity than natural cellulose, and includes hydrated cellulose (cellulose II) obtained by dissolving natural cellulose (cellulose I) in a predetermined solvent such as carbon disulfide or copper ammonia solution and then reprecipitation, as well as cellulose derivatives that have undergone certain chemical modifications in that process. Furthermore, it also includes hydrated cellulose obtained by alkali treatment or the like, even if natural cellulose is not dissolved.

[0012] Examples of the above-mentioned regenerated cellulose include rayon, polynosic, cupro, lyocell, fortisan, mercerized cotton, acetate, and the like. Furthermore, in this invention, regenerated cellulose fiber means a raw fiber obtained by spinning the above-mentioned regenerated cellulose raw material, and a fiber obtained by twisting only the raw fiber or by blending it with fibers made from other raw materials. Furthermore, in this invention, woven or knitted fabric means a fabric-like material such as a woven fabric, knitted fabric, or nonwoven fabric, and a molded article obtained by sewing such fabric.

[0013] The present invention is widely applicable to regenerated cellulose fibers and knitted or woven fabrics containing the regenerated cellulose fibers. By performing the treatment according to the present invention, it is possible to suppress the shrinkage of the knitted or woven fabric during washing such as water washing, and also to suppress the generation of "wrinkles" in the knitted or woven fabric due to partial shrinkage of the regenerated cellulose fibers or the like. In this specification, when referring to regenerated cellulose fibers or the like, it shall mean the knitted or woven fabric containing the regenerated cellulose fibers together with the above-mentioned regenerated cellulose fibers.

[0014] Among regenerated cellulose fibers or the like, particularly in the case of regenerated cellulose fibers or the like containing a regenerated cellulose component at a ratio of 1 wt% or more based on the total fiber weight, effective effects can be produced by the treatment according to the anti-shrinkage treatment method of the present invention. Further, in the case of regenerated cellulose fibers or the like containing a regenerated cellulose component at a ratio of 10 wt% or more, 30 wt% or more, or 50 wt% or more, or in the case of fibers or knitted or woven fabrics substantially composed of regenerated cellulose by containing 70 wt% or more, 90 wt% or more of the regenerated cellulose component, by performing the treatment according to the treatment method of the present invention, the swelling of the regenerated cellulose fibers when hydrated by water washing or the like is reduced, and thus it becomes possible to effectively reduce the shrinkage when dried thereafter.

[0015] The regenerated cellulose fibers according to the present invention and the knitted or woven fabric containing the regenerated cellulose fibers are characterized in that an adsorbate containing cellulose nanofibers (hereinafter sometimes referred to as "CNF") is adsorbed on the fiber surface.

[0016] The above CNF is a general term for fine cellulose fibers obtained by extracting cellulose microfibrils, which are bundles of highly crystalline cellulose molecules contained in plant cell walls and the like, by various treatment methods (see, for example, Patent Document 4, etc.). CNF typically has an average fiber diameter of about 2 to 150 nm and an aspect ratio (fiber length / fiber diameter) of about 100 to 10,000, and is a very fine fibrous substance compared to the elementary fibers of regenerated cellulose (with a diameter of about 10 μm), and is also said to be a tough fibrous cellulose with a strength per unit cross-sectional area greater than that of steel.

[0017] In the regenerated cellulose fibers and the like according to the present invention, the mechanism by which the dimensional stability is improved compared to untreated regenerated cellulose fibers is not necessarily clear. On the other hand, as shown in the examples, in the regenerated cellulose fibers treated by the anti-shrinkage treatment method according to the present invention, it is observed that they have a structure in which fine fibrous CNF or an aggregate of CNF in which the CNF is aggregated in a fibrous form is adsorbed on the regenerated cellulose fibers. From this, it is推测 that tough CNF entangles and adsorbs to the regenerated cellulose fibers, physically constraining the regenerated cellulose fibers, and as a result, inhibiting an increase in the fiber diameter and the like when the regenerated cellulose fibers absorb water and swell, thereby improving the swelling resistance. Also, it is considered that the rearrangement of cellulose molecules in the regenerated cellulose fibers is hindered by the physical constraint by the CNF, thereby suppressing the shrinkage after drying.

[0018] The CNF used in the present invention can be used without particular limitation regardless of the method for producing CNF when obtaining CNF from a cellulose raw material, as long as it can be dispersed in a dispersion medium such as an aqueous solution. For example, CNF produced by mechanically defibrating cellulose fibers, CNF produced by subjecting cellulose fibers to acid hydrolysis or alkali treatment, CNF commercially available in a powdery form, or CNF commercially available in the form of an aqueous dispersion, etc., can be used, and a dispersion containing this at an appropriate concentration can be used as a treatment liquid.

[0019] The shrinkage prevention treatment method according to the present invention allows CNF to adsorb onto regenerated cellulose fibers, thereby limiting the volume increase due to water absorption of the regenerated cellulose fibers and suppressing their swelling. Even a small amount of CNF adsorbed onto the regenerated cellulose fibers can produce the effects of the present invention. On the other hand, when 0.01 wt% or more of CNF is adsorbed onto and coated on the surface of the regenerated cellulose fiber, the spacing between CNF particles on the surface of the regenerated cellulose fiber becomes smaller, making it possible to effectively suppress swelling when the regenerated cellulose fiber absorbs water. Furthermore, by adsorbing CNF at a rate of 0.05 wt% or 0.1 wt% or more and coating the fibers, it is possible to significantly improve the swelling properties of the fibers. Moreover, by adsorbing 0.5 wt% or 1.0 wt% or more of CNF onto the regenerated cellulose fiber, it is possible to substantially coat the entire surface of the regenerated cellulose fiber with CNF.

[0020] Furthermore, while there is no upper limit to the amount of CNF used for coating in terms of improving the swelling properties of the fibers, excessive amounts of CNF adsorbed onto regenerated cellulose fibers tend to impair the flexibility of the fibers, resulting in what is known as "paperization." Therefore, in order to maintain the texture of the regenerated cellulose fibers coated with CNF, it is desirable to limit the amount of adsorbed CNF to 5 wt% or less, based on the fiber weight.

[0021] Considering that the diameter of the raw fibers of commonly used regenerated cellulose fibers is about 10 μm, for example, when a fiber is coated with about 0.1 wt% CNF, the average thickness of the CNF coating layer is estimated to be about 2.5 nm. Since this value is less than the diameter of commonly known CNF, it is thought that this amount of CNF does not cover the entire surface of the regenerated cellulose fiber, but rather is adsorbed randomly at predetermined intervals. In other words, the fiber surface treated by the method according to the present invention does not necessarily need to be completely covered with CNF, and when the fiber absorbs water, the swelling property can be improved by adsorbing CNF onto the fiber surface at a density that can suppress volume increase due to swelling.

[0022] Specifically, CNF adsorbing and covering 10% or more of the fiber surface area improves the swelling properties of regenerated cellulose fibers, and adsorbing CNF over 30% or 50% of the surface area can produce a significant improvement in swelling properties. Furthermore, even in configurations where the entire surface of the regenerated cellulose fiber is substantially covered by CNF, and even further covered by multiple layers of CNF, a significant improvement in swelling properties can be produced. The CNF adsorbed on the surface of the regenerated cellulose fiber can be observed, for example, using a scanning electron microscope, and the coverage rate of the regenerated cellulose fiber can be evaluated.

[0023] The CNF adsorption treatment of regenerated cellulose fibers can be carried out by a CNF adsorption step in which the regenerated cellulose fibers are immersed in a CNF dispersion containing CNF in an appropriate proportion to impregnate and adsorb the CNF into the regenerated cellulose fibers, followed by a drying step in which the regenerated cellulose fibers are dried. Furthermore, after the drying step, the regenerated cellulose fibers can be set (shape stabilization treatment) at a temperature of approximately 150 to 200°C while maintaining the regenerated cellulose fibers in a predetermined shape, thereby imparting the initial shape to the regenerated cellulose fibers on which CNF has been adsorbed.

[0024] The treatment for adsorbing CNF onto the above-mentioned regenerated cellulose fibers may, for example, involve adsorbing CNF onto single regenerated cellulose fibers before spinning, or onto regenerated cellulose fibers after scouring or bleaching, or onto woven or knitted fabrics obtained using such fibers.

[0025] Furthermore, the processing method according to the present invention involves immersing regenerated cellulose fibers, etc., in a dispersion of CNF to impregnate and adsorb the CNF onto the regenerated cellulose fibers, etc., and is similar to the dyeing process for textile products. Therefore, it can be performed as part of a dyeing process for textiles or woven / knitted fabrics. In other words, to the extent that it does not hinder the effects of the present invention, CNF may be adsorbed onto textiles or woven / knitted fabrics before or after dyeing, or CNF may be mixed with dyes, etc., to adsorb CNF onto regenerated cellulose fibers, etc., at the same time as dyeing.

[0026] Furthermore, it is possible to use a combination of resin-based processing, which is performed to impart various properties to regenerated cellulose fibers, etc., and processing using CNF according to the present invention. In other words, various combinations of resin-based processing are possible, such as performing resin processing on regenerated cellulose fibers, etc. that have undergone CNF processing according to the present invention, performing CNF processing and resin processing simultaneously using a processing solution in which resin components, etc., are mixed with a dispersion liquid containing CNF, and performing CNF processing according to the present invention on regenerated cellulose fibers, etc. that have undergone resin processing.

[0027] As a means of adsorbing CNF onto regenerated cellulose fibers, for example, a method classified as so-called immersion dyeing, in which the fibers are immersed in a bath containing a dissolved dye and the dye is absorbed by the fibers, can be used as appropriate. By using a dispersion of CNF as the bath, CNF can be easily adsorbed. For example, by using a high-pressure immersion dyeing process in which regenerated cellulose fibers are immersed in a dispersion of CNF, sealed in a container, heated to about 120°C and maintained under high temperature and pressure, it is possible to efficiently adsorb the CNF contained in the dispersion onto the regenerated cellulose fibers.

[0028] Furthermore, in a padding process performed as a finishing step after dyeing of woven or knitted fabrics containing regenerated cellulose fibers, the woven or knitted fabric containing regenerated cellulose fibers may be immersed in a treatment solution containing CNF to adsorb the CNF, and then the CNF may be adsorbed onto the regenerated cellulose fibers by processes such as dewatering with rollers, drying, and heat treatment (curing).

[0029] Furthermore, CNF can also be adsorbed onto the surface of regenerated cellulose fibers by simply immersing them in a CNF dispersion to adsorb CNF onto the fiber surface, followed by drying or heat treatment, thereby producing a shrinkage-preventing effect. In addition, CNF can be adsorbed onto the surface of regenerated cellulose fibers using methods such as spraying, coating, and printing. Furthermore, by applying CNF adsorption treatment to woven or knitted fabrics, particularly those containing regenerated cellulose fibers, CNF is expected to adsorb to the intersecting points of the fibers within the fabric, thereby suppressing slippage between fibers and more effectively producing shrinkage prevention effects.

[0030] In the processing method according to the present invention, the dispersion medium for dispersing CNF can be any suitable dispersion medium within a range that does not particularly harm the regenerated cellulose fibers, etc. being processed. As a CNF dispersion, a CNF-containing aqueous solution in which CNF is dispersed in an aqueous solution is commercially available, and it is possible to perform the processing according to the present invention using a CNF aqueous dispersion obtained by appropriately diluting such a CNF-containing aqueous solution. On the other hand, it is preferable to perform the processing according to the present invention using a dispersion obtained by dispersing CNF in an organic solvent that has low aggressiveness towards regenerated cellulose fibers, etc., such as those used in general dry cleaning, etc., in order to prevent swelling of the regenerated cellulose fibers, etc., due to water absorption that occurs during the processing.

[0031] In the processing method according to the present invention, it is desirable to determine the amount (concentration) of CNF in the CNF dispersion used, taking into consideration the amount of CNF adsorbed onto the regenerated cellulose fibers, etc., after processing. When CNF is adsorbed onto regenerated cellulose fibers, etc., by the above immersion dyeing process, it is possible to adsorb almost the entire amount of CNF in the CNF dispersion onto the regenerated cellulose fibers, etc. Therefore, a treatment solution can be used in which an amount of CNF is dispersed according to the amount of regenerated cellulose fibers, etc. to be treated and the target amount of CNF adsorption.

[0032] Furthermore, when CNF is adsorbed onto regenerated cellulose fibers by padding or other processes, which involve immersing regenerated cellulose fibers in a treatment solution containing CNF under predetermined conditions and then dehydrating them, it is desirable to determine the CNF concentration in the treatment solution so that the desired amount of CNF is adsorbed onto the regenerated cellulose fibers after treatment. For example, by immersing regenerated cellulose fibers in a treatment solution containing approximately 0.001% or more CNF, or by performing padding using the said treatment solution, it is possible to reduce the swelling properties of the regenerated cellulose fibers and reduce the amount of shrinkage after washing.

[0033] When regenerated cellulose fibers are immersed in a dispersion of CNF, the CNF, or its fibrous aggregates, that come into contact with the regenerated cellulose fibers become entangled with and adhere to the surface of the fibers. Furthermore, it is believed that the CNF is effectively adsorbed onto the surface of the regenerated cellulose fibers mainly because the two have the same molecular structure. It is then inferred that the adsorption of high-strength CNF suppresses subsequent changes in shape due to swelling of the regenerated cellulose fibers, and as a result, shrinkage during washing is suppressed.

[0034] In the shrink-proofing treatment of regenerated cellulose fibers, etc. according to the present invention, it is also possible to further coat the regenerated cellulose fibers, etc., on which CNF has been adsorbed with an appropriate resin component, depending on the purpose of imparting a desired texture or water repellency to the regenerated cellulose fibers, etc. It is also possible to coat the regenerated cellulose fibers, etc., using CNF that has been pre-mixed with a resin component, etc. In particular, by coating with a resin component, etc., in addition to adsorbing CNF, the tear strength of woven or knitted fabrics containing regenerated cellulose fibers can be improved.

[0035] Examples of resin components used as described above include fluorine-based and paraffin wax-based resin components, which are primarily intended to hydrophobize the surface of regenerated cellulose fibers. Furthermore, using glyoxal resin, which is commonly used to prevent wrinkles and shrinkage of cellulose fibers, is preferable because it is expected to cause cross-linking reactions between cellulose molecules contained in the fibers and CNF, thereby further enhancing the effects of the CNF treatment according to the present invention.

[0036] In CNF dispersions, in which regenerated cellulose fibers are immersed for the purpose of CNF adsorption, appropriate chemicals may be mixed in to facilitate the CNF adsorption treatment. For example, various dispersants can be used to properly disperse CNF in the CNF dispersion. Examples of dispersants include polymers that function as various surfactants, and orange oil.

[0037] Furthermore, in CNF dispersions, it is effective to adjust the acidity according to the type of fiber being modified in order to promote the adhesion of CNF to regenerated cellulose fibers. Chemicals used to adjust the acidity include sodium hydroxide or soda ash for alkalizing, and oxalic acid, acetic acid, or malic acid for acidification. The present invention will be described in more detail below using examples, but the present invention is not limited to the following examples. [Examples]

[0038] [Example 1] The following treatment was performed on a cupro fabric (44T / 24F 2330T / M) to adsorb CNF onto the surface of the fibers constituting the fabric. For the adsorption treatment of fiber surfaces with CNF, a CNF-containing aqueous solution (Reocrista I-2SP, CNF content: 2.2 wt%, hereinafter sometimes referred to as "Stock Solution 1") manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used. A dispersant (Alcosol GL, manufactured by Meisei Chemical Industry Co., Ltd.) equivalent to 2 wt% of Stock Solution 1 was added, and then the solution was diluted with industrial water so that the weight of CNF solids contained in the treatment solution (300 ml) used for each treatment amounted to the amount shown in Table 1. As explained below, 10 g of fabric was immersed in each treatment solution, so the weight ratio of CNF to fabric in each example is the value shown in the right column of Table 1.

[0039] The treatment was carried out by immersing a 10g sample of fabric in each treatment solution (300ml), sealing it in a metal container, heating it to 120°C, and holding it there for 30 minutes (high-pressure immersion dyeing). During this treatment, the fabric is thought to be maintained at a pressure of approximately 2 atmospheres. For "Comparative Example 1" in Table 1, the treatment was carried out similarly, holding it at 120°C for 30 minutes, except that industrial water was used. After the above treatment, each fabric was dried indoors, and then, in its shaped state, set with hot air at 170°C for approximately 60 seconds (shape stabilization treatment) before being used for the following evaluations.

[0040] [Table 1]

[0041] In the above-described high-pressure immersion dyeing process, the following evaluation was performed to confirm the adsorption properties of CNF contained in the processing solution when it is adsorbed onto the fiber surface. A processing solution (900 ml) similar to that used in Examples 1-4 was prepared, and electrolytic treatment was performed at 14 V for 30 minutes to precipitate CNF dispersed and dissolved in the processing solution. In addition, the processing solution (900 ml) after the adsorption treatment of the fabric corresponding to Examples 1-4 was subjected to the same electrolytic treatment to precipitate CNF remaining in the processing solution.

[0042] Figures 1A and 1B show photographs illustrating the appearance of CNF precipitated from the treatment solution before and after the above treatment. As shown in Figures 1A and 1B, the amount of CNF remaining in the treatment solution after use (Figure 1B) is only slightly more than the amount of CNF before treatment (Figure 1A), indicating that the majority of the CNF contained in the treatment solution is removed from the solution by adsorption onto the fabric or other means through the above treatment.

[0043] Figures 2A and 2B show SEM images of the fiber surfaces of the fabrics before and after the above treatment (Examples 1-4). As shown in Figure 2B, it was observed that the fiber surface of the fabric treated in water without CNF maintained the characteristic surface properties formed when cupro fibers are spun. On the other hand, as shown in Figure 2A, it was observed that the fiber surface of the fabric treated in a treatment solution containing CNF had different properties from the surface properties of the cupro fibers.

[0044] The surface properties of the fibers treated with the treatment solution containing the CNF were understood to be due to the CNF in the treatment solution randomly adsorbing and integrating with the surface of the cupro fibers, forming a network-like coating on the surface of the cupro fibers. Furthermore, the streaks observed parallel to the fibers were presumed to be wrinkles caused when the CNF-adsorbed surface could not follow the interior of the fiber as it dried and contracted in volume under wet conditions.

[0045] Considering that both cupro and CNF are primarily composed of cellulose and have similar densities, for example, when 0.1 to 0.5 wt% of CNF is uniformly adsorbed onto cupro, the radius of the cupro fiber increases by approximately 0.05 to 0.25%, and this increase corresponds to the average thickness of the CNF layer on the surface of the cupro fiber. Thus, when 0.1 to 0.5 wt% of CNF is attached to cupro fibers with a radius of approximately 5 μm, as shown in Figures 2A and B, the average thickness of the CNF layer is estimated to be approximately 2.5 to 12.5 nm. However, since this estimated average thickness corresponds to the diameter of the CNF used (approximately 3 to 10 nm), it can be inferred that the above amount of CNF does not uniformly adsorb onto the surface of the regenerated cellulose fiber to form a film, but rather that the CNF is adsorbed at predetermined intervals on the surface of the regenerated cellulose fiber. In other words, in order to obtain the effects produced by adsorbing CNF onto the surface of regenerated cellulose fibers as shown below, it is not necessarily required that the CNF adsorb completely onto the fiber surface to form a film. It is thought that adsorption of CNF to the extent that it covers only a part of the fiber surface is sufficient to reduce the degree of swelling of the fiber and subsequent shrinkage during drying.

[0046] For each fabric treated with the above-described CNF, the degree of shrinkage during the subsequent drying process after being immersed in water and moistened was evaluated. The evaluation involved marking each fabric at 10 cm intervals (two locations) and immersing it in industrial water at room temperature for approximately 12 hours to allow it to absorb sufficient water. The dimensional change during the wet state was then evaluated by measuring the distance between the markings. Next, each fabric was air-dried indoors, and the dimensional change after drying was evaluated by measuring the distance between the markings after drying.

[0047] Table 2 shows the results of the above evaluation. In Table 2, wet shrinkage and dry shrinkage are shown as percentages obtained by dividing the distance between the wet and dry markings by 10 cm, respectively. "+" (plus) indicates expansion, and "-" (minus) indicates contraction. As shown in Table 2, it was observed that the degree of expansion that occurred when each of the CNF-treated fabrics was wet was lower compared to the fabric without CNF treatment (Comparative Example 1). Furthermore, in terms of dimensional change after drying after wetting, a clear reduction in dimensions was observed in the fabric without CNF treatment (Comparative Example 1), whereas no substantial change in dimensions was observed in the fabric treated with CNF according to the present invention.

[0048] [Table 2]

[0049] The difference in swelling behavior of cupro fibers with and without CNF treatment was evaluated using the method described below. The evaluation was performed by measuring the diameter of cupro fibers in both the dry state and after immersion in water for 6 hours, using a polarizing microscope (Nikon ECLIPSE LOV100N POL, transmission observation under crossed nicols) for both untreated (Comparative Example 1) and treated (Examples 1-4).

[0050] Table 3 shows the results of the above evaluation. As shown in Table 3, in the fabric without CNF treatment (Comparative Example 1), swelling due to water absorption occurred until the cross-sectional area of ​​the fibers reached approximately 150%, whereas in the fabric treated with CNF according to the present invention (Examples 1-4), the degree of swelling was suppressed to approximately 120%. As shown in Table 3, the reason why the degree of fiber swelling is suppressed by CNF treatment is that the fibers are constrained by the tough CNF that is entangled on the fiber surface, making it difficult for them to swell beyond a certain level due to water absorption.

[0051] [Table 3]

[0052] For each fabric treated with the above-mentioned CNF, the tear strength was measured in both dry and wet conditions according to JIS L 1096 Method D (pendulum method). Table 4 shows the results of the tear strength measurements. As shown in Table 4, no substantial change in tear strength was observed in either the dry or wet conditions for the fabrics treated with the above-mentioned CNF.

[0053] [Table 4] [Example 2]

[0054] The following treatment was performed on a cupro fabric (84T / 90F 1630T / M) to adsorb CNF onto the surface of the fibers constituting the fabric. For the adsorption treatment of fiber surfaces with CNF, a CNF-containing aqueous solution (Selenpia, CNF content: 1.0 wt%, sometimes referred to as "Stock Solution 2") manufactured by Nippon Paper Industries Co., Ltd. was used as the treatment solution. This solution was prepared by adding a dispersant (Alcosol GL, manufactured by Meisei Chemical Industry Co., Ltd.) equivalent to 2 wt% of Stock Solution 2, and then diluting it with industrial water so that the weight ratio of CNF solids met the conditions shown in Table 5. In addition, for "Comparative Example 2" in Table 5, industrial water was used as the treatment solution.

[0055] The processing involved immersing the fabric in each processing solution using a padding device, then squeezing it with a roll until the wet pickup was 100% by weight, followed by drying, and finally setting it with hot air at 170°C for approximately 60 seconds (shape stabilization treatment), before using it for the following evaluations.

[0056] [Table 5]

[0057] For each fabric treated with the CNF described above, the degree of shrinkage that occurred during the process of wetting by immersion in water and then drying was evaluated, similar to Example 1. Table 6 shows the results of the evaluation. As shown in Table 6, Comparative Example 2 exhibited significant expansion when wet and shrinkage after drying, while Examples 2-1 to 2-5, which were treated with CNF, showed suppressed dimensional changes.

[0058] [Table 6]

[0059] Similar to Example 1, the difference in swelling behavior of cupro fibers with and without the CNF treatment was evaluated. Table 7 shows the results of the evaluation. As shown in Table 7, in the fabric without CNF treatment (Comparative Example 2), swelling due to water absorption occurred until the cross-sectional area of ​​the fibers was approximately 170%, whereas in the fabric treated with CNF according to the present invention (Examples 2-5), the degree of swelling was suppressed to approximately 116%.

[0060] [Table 7]

[0061] For each fabric treated with the above-described CNF, the tear strength was measured in both dry and wet conditions, as in Example 1. Table 8 shows the results of the tear strength measurements. As shown in Table 8, no substantial change in tear strength was observed in the CNF-treated fabrics, neither in dry nor wet conditions.

[0062] [Table 8] [Example 3]

[0063] In the following method, a fabric woven with a grid pattern using polyester yarn (100 denier) in the warp and weft directions (polyester ratio approximately 35%) was treated by coating the surface of the fibers constituting the fabric with CNF mixed with a resin component. Bemberg is a regenerated cellulose fiber that tends to shrink when washed with water, while polyester is a synthetic fiber that does not undergo substantial shrinkage when washed with water.

[0064] The processing solution used was the stock solution 2 used in Example 2 as the CNF source, mixed with industrial water in the proportions shown in Table 9, along with glyoxal resin (DIC Corporation, Beccamine N-80), Beccamine Corporation (DIC Corporation, Beccamine M-3) as resin components, catalyst (DIC Corporation, Catalyst 376), and dispersant (Meisei Chemical Industry Co., Ltd., Petrox P-200). The fabric was immersed in the processing solution using a padding device, then squeezed with a roll until the wet pickup was 100% by weight, dried, and then set in the shaped state with hot air at 170°C for approximately 60 seconds for evaluation. The evaluation was performed by hand washing tests at 40°C and boiling tests at 100°C for 10 minutes, followed by drying, and then evaluating the shrinkage rate.

[0065] [Table 9]

[0066] Table 10 shows the shrinkage rates after the hand washing and boiling tests described above. The shrinkage rate was calculated by measuring the distance between markings that had been set at 10 cm intervals. As shown in Table 10, untreated fabrics shrank by about 5% after hand washing and about 10% after the boiling test, while the shrinkage was significantly suppressed in the CNF-treated fabrics. In the untreated fabrics with high shrinkage rates, it was observed that polyester yarns that did not shrink substantially rose from the fabric, causing a crinkled appearance.

[0067] [Table 10] [Example 4]

[0068] The tear strength of a cupro fabric (warp: 56T / 60 2000S; weft: 84T90 1630SZ) was investigated when the following CNF was adsorbed onto the surface of the fibers constituting the fabric, and when resin processing was also performed.

[0069] CNF adsorption treatment: Under the same conditions as in Example 1-1, the above fabric was subjected to high-pressure immersion dyeing to coat it with CNF, then dried, and set with hot air at 170°C for approximately 60 seconds (Example 4-1). Resin processing treatment: The fabric that had undergone the above CNF adsorption treatment (Example 4-1) was further padded with a processing solution containing glyoxal resin (DIC Corporation, Beccamine N-80; 1 wt%, Beccamine M-3; 1 wt%), catalyst (DIC Corporation, Catalyst 376; 0.5 wt%), and 0.5 wt% CNF derived from the original solution 1. The fabric was then pressed with a roll until the wet pickup was 100% by weight, dried, and then subjected to the same setting treatment as above (Example 4-2).

[0070] Table 11 shows the tear strength (dry) for Examples 4-1 and 4-2, measured using the same method as in Example 1, in comparison with the untreated fabric (Comparative Example 4). As shown in Table 11, it was observed that the tear strength of the fabric treated with CNF adsorption was improved by further resin processing.

[0071] [Table 11] [Example 5]

[0072] To investigate the difference in effectiveness between immersion dyeing with high pressure and padding processes when adsorbing CNF (cellulose nanofiber) onto fabric (fibers) using CNF pre-mixed with resin components, the following methods were used to study a fabric (Tanaka Shokai TNK-471-A) with warp threads of diacetate (AC:75d S800T / M), weft threads of cupro (Cu:SB 60 / -), and a blend ratio of AC70% / Cu30%.

[0073] For the immersion dyeing high-pressure processing, the stock solution used in Example 1 as the CNF source was mixed with glyoxal resin (DIC Corporation, Beccamine N-80), Beccamine Corporation (DIC Corporation, Beccamine M-3), and a catalyst (DIC Corporation, Catalyst 376) in the proportions shown in Table 12, and industrial water was added to make a total volume of 300 ml, which was used as the processing solution. The processing was carried out by immersing a piece of fabric (10 g) in the processing solution (300 ml), sealing it in a metal container, heating it to 100°C, and holding it for 20 minutes (immersion dyeing high-pressure processing). After processing, the fabric was dried at room temperature, and then set with hot air at 170°C for 60 seconds (Example 5-1). For comparison, a sample was prepared that was processed in the same manner as above, except that industrial water was used as the processing solution (Comparative Example 5).

[0074] [Table 12]

[0075] Furthermore, the padding process was carried out using the stock solution 1 used in Example 1 as the CNF source, mixed with industrial water in the proportions shown in Table 13, and containing glyoxal resin (DIC Corporation, Beccamine N-80), glyoxal resin (DIC Corporation, Beccamine M-3), and catalyst component (DIC Corporation, Catalyst 376). In order to exclude the effect of the hydrothermal treatment in Example 5-1 on the fibers, the fabric obtained in Comparative Example 5 was used as a sample for padding (Example 5-2).

[0076] [Table 13]

[0077] Table 14 shows the results of measuring the tear strength in a dry state for Examples 5-1, 5-2 and Comparative Example 5 using the same method as in Example 1. As shown in Table 14, the tear strength after treatment was significantly improved when CNF treatment was performed by padding. This result is presumed to be due to changes in the form in which CNF is adsorbed to the fibers and the state of the resin, depending on the treatment method used to coat the fibers with CNF.

[0078] [Table 14] [Industrial applicability]

[0079] By adsorbing CNF or the like onto regenerated cellulose fibers, the shrinkage of regenerated cellulose fibers during washing or other processes can be suppressed.

Claims

1. A regenerated cellulose fiber having adsorbent material on the surface of a twisted yarn containing subfibers obtained by spinning a regenerated cellulose raw material, wherein the adsorbent material contains cellulose nanofibers and resin, and the resin contains at least one resin selected from fluororesins, paraffin wax resins, and glyoxal resins.

2. The regenerated cellulose fiber according to Claim 1, characterized in that the weight percentage of cellulose nanofibers is 0.01 wt% or more.

3. The regenerated cellulose fiber according to claim 1 or 2, characterized in that the adsorbent is adsorbed onto a single regenerated cellulose fiber, or onto a regenerated cellulose fiber that has undergone scouring and bleaching but has not yet been made into a woven or knitted fabric.

4. The regenerated cellulose fiber according to claim 1 or 2, characterized in that the adsorbent is adsorbed onto the regenerated cellulose fiber processed into a woven or knitted fabric.

5. A woven or knitted fabric characterized by containing the regenerated cellulose fibers described in any one of Claims 1 to 4.

6. A cellulose nanofiber adsorption step comprising immersing regenerated cellulose fibers in a cellulose nanofiber dispersion containing at least one resin component selected from fluororesin, paraffin wax resin, and glyoxal resin, and in which cellulose nanofibers are dispersed, to adsorb adsorbed material containing cellulose nanofibers, A method for preventing shrinkage of regenerated cellulose fibers, characterized by including a drying step of drying the fibers on which the adsorbed material containing the cellulose nanofibers has been adsorbed.

7. A cellulose nanofiber adsorption step in which regenerated cellulose fibers are immersed in a cellulose nanofiber dispersion in which cellulose nanofibers are dispersed, thereby adsorbing adsorbed material containing cellulose nanofibers, A drying process in which regenerated cellulose fibers on which adsorbent material containing cellulose nanofibers has been adsorbed are dried. A method for preventing shrinkage of regenerated cellulose fibers, characterized by further comprising a resin adsorption step, after the drying step, in which the regenerated cellulose fibers are immersed in a solution containing at least one resin component selected from fluororesins, paraffin wax resins, and glyoxal resins.

8. The method for preventing shrinkage of regenerated cellulose fibers according to claim 6 or 7, characterized in that the regenerated cellulose fibers are processed into a woven or knitted fabric.

9. The method for shrink-proofing regenerated cellulose fibers according to claim 6 or 7, characterized in that the regenerated cellulose fibers are single regenerated cellulose fibers, or regenerated cellulose fibers that have undergone scouring and bleaching but have not yet been made into a woven or knitted fabric.

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