Method for treating regenerated cellulose fibers and treated regenerated cellulose fibers

Abstract

To provide a regenerated cellulose fiber which is stabilized in size by reducing the shrinkage after water washing and the like. A regenerated cellulose fiber characterized in that a surface of the regenerated cellulose fiber has an adsorbate containing cellulose nanofiber.

Description

Technical Field

[0001] This invention relates to a method for dimensionally stabilizing regenerated cellulose fibers obtained by spinning or the like, as well as the regenerated cellulose fibers treated by this method and a fabric containing the regenerated cellulose fibers. This application claims priority to Japanese Patent Application No. 2020-10451, filed on January 25, 2020, the disclosure of which is incorporated herein by reference. Background Technology

[0002] Regenerated cellulose fibers such as rayon, polynosic fiber, cupra, lyocell, and acetate are widely used in curtains, handcrafted fabrics, wrapping cloths, handbags, and footwear due to their unique drape, the distinctive feel and luster of cellulose filaments, and their ease of movement. In addition to being used in general women's clothing and / or stole, and as linings for men's and women's wear, they also possess excellent heat retention and moisture absorption properties. Furthermore, their use in underwear is expanding in recent years, leveraging the moisture-absorbing and heat-generating effects of regenerated cellulose fibers on their surface for functional underwear.

[0003] On the other hand, the aforementioned regenerated cellulose fibers are known to have the following characteristics: due to their high hygroscopicity, when immersed in water and swollen during washing, the fiber length shrinks during the subsequent drying process. Therefore, fabrics using regenerated cellulose fibers are generally difficult to wash and require dry cleaning.

[0004] The swelling and accompanying shrinkage of the regenerated cellulose fibers described above are considered to be caused by the process of manufacturing regenerated cellulose fibers from cellulose raw materials and originate from the structure of the fibers themselves. Specifically, it is known that in the manufacturing of regenerated cellulose fibers, the crystallinity of natural cellulose is reduced during the spinning process, which involves dissolving natural cellulose raw materials in carbon disulfide, copper ammonia solution, etc. Therefore, it can be considered that in regenerated cellulose fibers, swelling occurs because moisture easily penetrates between the cellulose molecules constituting the fibers, and shrinkage occurs after drying due to the rearrangement of cellulose molecules within the fibers during swelling.

[0005] To address the aforementioned problems, various improvement measures have been proposed. For example, Patent Document 1 describes a method that suppresses fabric damage caused by washing by applying a long-chain hydrocarbon compound to the surface of regenerated cellulose fibers, etc. Furthermore, Patent Document 2 describes a method that allows the coated regenerated cellulose fibers, etc., to be washed with water by coating the surface with an amino-modified silicone. On the other hand, Patent Document 3 describes a method that applies a specific crosslinking agent that reacts with the hydroxyl groups in cellulose molecules to regenerated cellulose fibers, forming crosslinked structures between and within cellulose molecules, thereby suppressing the rearrangement of cellulose molecules within the fiber and thus suppressing shrinkage caused by washing.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2011-6808

[0009] Patent Document 2: Japanese Patent Application Publication No. 2012-1830

[0010] Patent Document 3: Japanese Patent Application Publication No. 2005-113333

[0011] Patent Document 4: Japanese Patent Application Publication No. 2008-1728 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] The objective of this invention is to provide a novel treatment method that improves upon the problems associated with the aforementioned regenerated cellulose fibers, particularly for reducing shrinkage after washing of fabrics containing regenerated cellulose fibers to achieve dimensional stability. Furthermore, another objective of this invention is to provide regenerated cellulose fibers treated by this method, and a fabric containing the regenerated cellulose fibers.

[0014] Methods for solving problems

[0015] To address the aforementioned issues, the present invention provides the following means.

[0016] (1) A regenerated cellulose fiber, wherein the surface of the regenerated cellulose fiber has an adsorbent containing cellulose nanofibers.

[0017] (2) In the above-mentioned regenerated cellulose fibers, the weight ratio of cellulose nanofibers is more than 0.01 wt%.

[0018] (3) The above-mentioned regenerated cellulose fibers also contain resin.

[0019] (4) A fabric comprising the above-mentioned regenerated cellulose fibers.

[0020] (5) A shrinkage prevention treatment method for regenerated cellulose fibers, comprising: a cellulose nanofiber adsorption step, wherein the regenerated cellulose fibers are immersed in a cellulose nanofiber dispersion in which cellulose nanofibers are dispersed, thereby causing the regenerated cellulose fibers to adsorb cellulose nanofibers; and a drying step, wherein the regenerated cellulose fibers adsorbed with the cellulose nanofibers are dried.

[0021] (6) In the above-mentioned shrinkage prevention treatment method for regenerated cellulose fibers, the cellulose nanofiber dispersion contains resin components.

[0022] (7) In the above-mentioned method for preventing shrinkage of regenerated cellulose fibers, after the above-mentioned drying process, a resin adsorption process is further included, in which the regenerated cellulose fibers are immersed in a solution containing resin components.

[0023] (8) In the above-mentioned shrinkage prevention treatment method for regenerated cellulose fibers, the above-mentioned regenerated cellulose fibers have been processed into fabrics.

[0024] Invention Effects

[0025] According to the present invention, the size stabilization of regenerated cellulose fibers can be achieved, and the shrinkage of regenerated cellulose fibers and fabrics containing regenerated cellulose fibers after washing can be reduced. Attached Figure Description

[0026] Figure 1A This is a photograph showing an example of the state after CNF has precipitated from a CNF dispersion.

[0027] Figure 1B This is a photograph showing an example of the state after CNF has been precipitated from a CNF dispersion after shrinkage treatment of regenerated cellulose fibers.

[0028] Figure 2A This is a SEM image of cuprammonium fiber adsorbed with CNF.

[0029] Figure 2B This is an SEM image of cuprammonium fiber. Detailed Implementation

[0030] As the fiber used in this invention, it is preferably a fiber known as regenerated cellulose fiber. The regenerated cellulose in this invention refers to cellulose and cellulose derivatives that exhibit higher hygroscopicity compared to natural cellulose, and includes hydrated cellulose (cellulose II) formed by dissolving natural cellulose (cellulose I) in a specific solvent such as carbon disulfide or a copper ammonia solution and then re-precipitating it, as well as cellulose derivatives that undergo certain chemical modifications during this process. Furthermore, it also includes substances that can be produced as hydrated cellulose through alkali treatment or the like, even without dissolving natural cellulose.

[0031] Examples of regenerated cellulose fibers include rayon, polynitrocellulose (Polinosic fiber), cupro fiber, lyocell fiber, Fortisan fiber, mercerized cotton, and cellulose acetate. Furthermore, in this invention, regenerated cellulose fiber refers to the original fiber obtained by spinning the aforementioned regenerated cellulose raw materials, or the fiber obtained by twisting the original fiber or blending it with fibers composed of other raw materials. Additionally, in this invention, fabric refers to woven fabrics, braided fabrics, nonwoven fabrics, and other fabric-like articles, as well as shaped bodies formed by sewing such fabrics.

[0032] This invention can be widely applied to regenerated cellulose fibers and fabrics containing regenerated cellulose fibers. By performing the treatment involved in this invention, shrinkage of fabrics during washing and other processes can be suppressed, and wrinkles that occur on the fabric due to partial shrinkage of the regenerated cellulose fibers can be suppressed. Furthermore, in this specification, when referred to as regenerated cellulose fibers, it refers to the aforementioned regenerated cellulose fibers and fabrics containing them.

[0033] In regenerated cellulose fibers, particularly those containing 1 wt% or more of regenerated cellulose relative to the total fiber weight, the shrinkage-resistant treatment method according to the present invention can produce effective results. Furthermore, in regenerated cellulose fibers containing 10 wt% or more, 30 wt% or more, or 50 wt% or more of regenerated cellulose, or fibers or fabrics substantially composed of regenerated cellulose containing 70 wt% or more or 90 wt% or more of regenerated cellulose, treatment using the method according to the present invention reduces swelling of the regenerated cellulose fibers when wetted by washing or other processes, thereby effectively reducing shrinkage during subsequent drying.

[0034] The regenerated cellulose fiber and the fabric containing the regenerated cellulose fiber involved in this invention are characterized in that an adsorbent containing cellulose nanofibers (hereinafter, sometimes referred to as "CNF") is adsorbed onto the fiber surface of the regenerated cellulose fiber.

[0035] CNF is a general term for fine cellulose fibers obtained by extracting cellulose microfibrils through various processing methods. These cellulose microfibrils are bundles of highly crystalline cellulose molecules contained in plant cell walls, etc. (see, for example, Patent Document 4, etc.). CNF is typically a fibrous material with an average fiber diameter of about 2 to 150 nm, an aspect ratio (fiber length / fiber diameter) of about 100 to 10000, and is extremely fine compared to the original fibers of regenerated cellulose (about 10 μm in diameter). It is also known as a strong and tough fibrous cellulose with a strength of steel or higher per unit cross-sectional area.

[0036] In the regenerated cellulose fibers and the like involved in this invention, the mechanism by which dimensional stability is improved compared to untreated regenerated cellulose fibers is not clearly understood. On the other hand, as shown in the examples, it was observed that in regenerated cellulose fibers treated by the anti-shrinkage treatment method involved in this invention, there is a structure in which fine fibrous CNFs, or CNF aggregates formed by the fibrous aggregation of these CNFs, are adsorbed onto the regenerated cellulose fibers. It can be inferred that the strong CNFs entangle and adsorb onto the regenerated cellulose fibers, thereby physically binding the regenerated cellulose fibers. As a result, when the regenerated cellulose fibers swell due to water absorption, the increase in fiber diameter is hindered, thus improving swelling resistance. Furthermore, it is believed that the physical binding caused by these CNFs prevents the rearrangement of cellulose molecules within the regenerated cellulose fibers, thereby suppressing shrinkage after drying.

[0037] The CNF used in this invention can be used without being particularly limited by the CNF manufacturing method when obtaining CNF from cellulose raw materials, as long as it can be dispersed in a dispersion medium such as an aqueous solution. For example, the following CNFs can be used: CNFs manufactured by mechanically defibrating cellulose fibers, CNFs manufactured by acid hydrolysis or alkali treatment of cellulose fibers and commercially available in powder form, and CNFs commercially available in the form of aqueous dispersions, etc., and formulated into a dispersion containing CNF at an appropriate concentration for use as a treatment solution.

[0038] It can be considered that through the anti-shrinkage treatment method involved in this invention, CNF is adsorbed onto the regenerated cellulose fibers, thereby limiting the volume increase of the regenerated cellulose fibers due to water absorption, thus suppressing the swelling of the regenerated cellulose fibers. Even if only a trace amount of CNF is adsorbed onto the regenerated cellulose fibers, the effects involved in this invention can be achieved. On the other hand, based on regenerated cellulose fibers, by adsorbing and covering the surface of the fibers with 0.01 wt% or more of CNF, the spacing between CNFs on the surface of the regenerated cellulose fibers is reduced, thereby effectively suppressing the swelling of the regenerated cellulose fibers when they contain water. Furthermore, by adsorbing and covering the fibers with CNF at a ratio of 0.05 wt% or more, or 0.1 wt% or more, the swelling properties of the fibers can be significantly improved. Moreover, by adsorbing CNF at a ratio of 0.5 wt% or more, or 1.0 wt% or more relative to the regenerated cellulose fibers, the entire surface of the regenerated cellulose fibers can be substantially covered with CNF.

[0039] Furthermore, from the viewpoint of improving the swelling properties of fibers, there is no upper limit to the amount of CNF covering. However, excessive CNF adsorption and coating on regenerated cellulose fibers may result in a tendency to impair the softness of the fibers, a phenomenon known as "paper-likeness." Therefore, from the viewpoint of maintaining the hand feel of CNF-coated regenerated cellulose fibers, it is preferable to keep the amount of adsorbed CNF at 5 wt% or less based on the fiber.

[0040] Considering that the diameter of the original fibers of commonly used regenerated cellulose fibers is about 10 μm, it can be estimated that when the fibers are covered with CNF at approximately 0.1 wt% relative to the fibers, the average thickness of the CNF coating layer is about 2.5 nm. Since this value is smaller than the generally known diameter of CNF, it can be assumed that the aforementioned amount of CNF does not cover the entire surface of the regenerated cellulose fibers, but rather adsorbs randomly at specific intervals. That is, the fiber surface treated by the method of the present invention does not need to be completely covered by CNF; the CNF adsorbs onto the fiber surface at a density sufficient to suppress volume increase due to swelling when the fibers are moist, thereby improving swelling properties.

[0041] Specifically, by ensuring that CNF adsorbs and covers an area of ​​10% or more on the fiber surface, the swelling properties of regenerated cellulose fibers can be improved. Furthermore, by ensuring that the CNF adsorption area is 30% or more, or 50% or more, a significant improvement in swelling properties can be achieved. Moreover, in the case where CNF substantially covers the entire surface of the regenerated cellulose fiber, and even further, in the case where multiple layers of CNF cover the entire surface of the regenerated cellulose fiber, a significant improvement in swelling properties can also be achieved. The CNF adsorbed onto the surface of the regenerated cellulose fiber can be observed, for example, using a scanning electron microscope (SEM), thereby allowing evaluation of the coverage rate of the regenerated cellulose fiber.

[0042] The adsorption treatment of regenerated cellulose fibers by CNF can be carried out by the following method: after a CNF adsorption step in which regenerated cellulose fibers or the like are immersed in a CNF dispersion in an appropriate proportion, thereby allowing CNF to permeate into the regenerated cellulose fibers or the like and thus adsorb CNF, a drying step is performed to dry the regenerated cellulose fibers or the like. Furthermore, after this drying step, by maintaining the regenerated cellulose fibers or the like in a specific shape and performing a set treatment (shape stabilization treatment) at about 150 to 200°C, the regenerated cellulose fibers or the like with CNF adsorbed on their surface can be given an initial shape.

[0043] For example, the treatment of adsorbing CNF onto the aforementioned regenerated cellulose fibers can be to adsorb CNF onto a single fiber of the regenerated cellulose fiber before spinning, or onto a regenerated cellulose fiber after scouring or bleaching, or to adsorb CNF onto a fabric obtained using the fiber.

[0044] Furthermore, the processing method involved in this invention involves immersing regenerated cellulose fibers or the like in a dispersion of CNF, allowing CNF to permeate and adsorb onto the regenerated cellulose fibers or the like. Since this method is similar to the dyeing process for fiber products, it can be performed as part of a dyeing process for fiber materials or fabrics. That is, without impairing the effects involved in this invention, for fiber materials or fabrics undergoing a dyeing process, CNF can be adsorbed onto the fiber materials or fabrics before or after dyeing, or CNF can be mixed with dyes or the like and adsorbed onto the regenerated cellulose fibers or the like during dyeing.

[0045] Alternatively, resin processing for imparting various properties to regenerated cellulose fibers can be combined with CNF treatment according to the present invention. That is, various combinations can be made with resin processing as follows: resin processing of regenerated cellulose fibers, etc., that have undergone CNF treatment according to the present invention; simultaneous CNF treatment and resin processing using a treatment liquid in which resin components are mixed in a CNF-containing dispersion; and CNF treatment according to the present invention on regenerated cellulose fibers, etc., that have undergone resin processing.

[0046] As a means of adsorbing CNFs onto regenerated cellulose fibers, for example, a method classified as so-called impregnation can be appropriately used. That is, the fibers are immersed in a bath in which dye is dissolved and the fibers absorb the dye completely. By using a CNF dispersion as the bath, CNF adsorption can be easily achieved. For example, by sealing regenerated cellulose fibers, etc., in a container while they are immersed in a CNF dispersion, and heating them to about 120°C and maintaining them under high temperature and high pressure for impregnation and high pressure processing, the CNF contained in the dispersion can be efficiently adsorbed onto the regenerated cellulose fibers, etc.

[0047] In addition, in the padding process, which is performed as a finishing process after dyeing fabrics containing regenerated cellulose fibers, the fabric containing regenerated cellulose fibers can be immersed in a treatment solution containing CNF to allow the fabric to adsorb CNF. Then, the regenerated cellulose fibers can adsorb CNF through dehydration, drying, heat treatment (curing) processes using rollers.

[0048] In addition, CNF can also be adsorbed onto the surface of regenerated cellulose fibers simply by immersing them in a CNF dispersion, allowing CNF to adsorb onto the fiber surface, followed by drying or heat treatment, thereby producing an anti-shrinkage effect. Alternatively, CNF can be adsorbed onto the surface of regenerated cellulose fibers using spraying, coating, or printing methods.

[0049] In addition, by subjecting fabrics containing regenerated cellulose fibers to CNF adsorption treatment, it is expected that CNF can also be adsorbed onto the interlacing parts of the fibers present in the fabric, thereby inhibiting the displacement between fibers and producing a more effective anti-shrinkage effect.

[0050] In the processing method according to the present invention, a suitable dispersion medium for dispersing CNF can be used within a range that does not particularly damage the regenerated cellulose fibers being processed. As a CNF dispersion, commercially available are CNF-containing aqueous solutions in which CNF is dispersed in an aqueous solution. The CNF aqueous dispersion obtained by appropriately diluting the CNF-containing aqueous solution can be used to perform the processing according to the present invention. On the other hand, by using an organic solvent, for example, that is less aggressive to regenerated cellulose fibers and the like in general dry cleaning, and using a CNF dispersion in that organic solvent to perform the processing according to the present invention, it is possible to prevent swelling of the regenerated cellulose fibers and the like due to water content during the processing, which is preferable from this perspective.

[0051] In the processing method of the present invention, it is preferable to determine the amount (concentration) of CNF in the CNF dispersion used based on the amount of CNF adsorbed on the regenerated cellulose fibers after treatment.

[0052] When CNF is adsorbed onto regenerated cellulose fibers or the like through the above-described impregnation process, since almost all of the CNF in the CNF dispersion can be adsorbed onto the regenerated cellulose fibers or the like, a treatment solution containing CNF can be used, wherein the amount of CNF in the treatment solution corresponds to the amount of regenerated cellulose fibers or the like related to the treatment and the amount of CNF adsorbed as the target.

[0053] In addition, when regenerated cellulose fibers or the like are impregnated in a treatment solution containing CNF under specific conditions, and then CNF is adsorbed onto the regenerated cellulose fibers or the like through padding or other processing such as dehydration, it is preferable to determine the CNF concentration in the treatment solution based on the amount of CNF that needs to be adsorbed onto the regenerated cellulose fibers or the like after treatment.

[0054] For example, by immersing regenerated cellulose fibers or the like in a treatment solution containing about 0.001% or more CNF, or by using the treatment solution for padding, it is possible to reduce the swelling of regenerated cellulose fibers or the like and reduce the shrinkage after washing.

[0055] By immersing regenerated cellulose fibers or the like in a dispersion containing CNF, the CNF, or its fibrous aggregates, upon contact with the regenerated cellulose fibers, is believed to entangle and adhere to the surface of the fibers. Furthermore, it is thought that CNF adsorbs well onto the surface of the regenerated cellulose fibers primarily because the regenerated cellulose fibers and CNF have the same molecular structure. Moreover, it is speculated that by using high-strength CNF for adsorption, morphological changes caused by subsequent swelling of the regenerated cellulose fibers are suppressed, and as a result, shrinkage during washing or similar processes is also suppressed.

[0056] In the shrink-proofing treatment of regenerated cellulose fibers and the like according to the present invention, depending on the purpose of imparting a desired hand feel or water resistance, an appropriate resin component may be further coated onto the regenerated cellulose fibers and the like that adsorbed with CNF. Furthermore, CNF, which is pre-mixed with a resin component, may also be used to coat the regenerated cellulose fibers and the like. In particular, in addition to CNF adsorption, coating with a resin component can improve the tear strength of fabrics containing regenerated cellulose fibers.

[0057] As the resin components used above, those primarily intended to hydrophobize the surface of regenerated cellulose fibers include fluorinated and paraffinic resins. Furthermore, glyoxal resins, typically used for wrinkle and shrinkage prevention in cellulose fibers, are preferred because they can induce cross-linking reactions between cellulose molecules contained in the fibers and CNFs, thus further enhancing the effectiveness of the CNF treatment described in this invention.

[0058] In CNF dispersions, which impregnate regenerated cellulose fibers for CNF adsorption, appropriate agents may be mixed in to facilitate CNF adsorption treatment. For example, various dispersants can be used to ensure good CNF dispersion in the CNF dispersion. Examples of dispersants include polymers that function as various surfactants and orange oil.

[0059] Furthermore, in CNF dispersions, adjusting the acidity according to the type of fiber being modified is effective in promoting CNF adhesion to regenerated cellulose fibers. As agents for adjusting acidity, sodium hydroxide or soda ash can be used for alkalization, while oxalic acid, acetic acid, or malic acid can be used for acidification.

[0060] The present invention will be described in more detail below through embodiments, but the present invention is not limited to the following embodiments.

[0061] Example 1

[0062] The following method is used to treat a fabric (44T / 24F 2330T / M) made of cupro fiber to allow CNF to be adsorbed onto the surface of the fibers constituting the fabric.

[0063] In the CNF adsorption treatment of the fiber surface, a solution obtained as the treatment liquid was used as follows: A CNF-containing aqueous solution (RHEOCRYSTA I-2SP, CNF content: 2.2 wt%, hereinafter sometimes referred to as "stock solution 1") manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd. was mixed with a dispersant (ALKOSOL GL, manufactured by Meisei Chemical Industry Co., Ltd.) at an amount equivalent to 2 wt% of stock solution 1, and then diluted with industrial water to prepare a treatment liquid (300 ml) for each treatment, such that the weight of the CNF solid component contained in the treatment liquid (300 ml) for each treatment was the amount listed in Table 1. Furthermore, as explained below, since 10 g of fabric was immersed in each treatment liquid, the weight ratio of CNF to fabric in each embodiment is the value shown in the right column of Table 1.

[0064] The treatment was performed by sealing 10g of fabric in a metal container, immersing it in 300ml of the respective treatment solution, heating it to 120°C, and maintaining the temperature for 30 minutes (impregnation high-pressure processing). It can be assumed that the fabric was maintained at a pressure of approximately 2 atmospheres during this treatment. Furthermore, for "Comparative Example 1" in Table 1, the treatment was similarly performed, maintaining the temperature at 120°C for 30 minutes, except that industrial water was used. Afterwards, the fabrics that underwent the above treatment were dried indoors and then, in their shaped state, subjected to hot air at 170°C for approximately 60 seconds (shape stabilization treatment) for the following evaluations.

[0065] [Table 1]

[0066]

[0067] In the above-described high-pressure dyeing process, to confirm the adsorption capacity of CNF contained in the treatment solution when adsorbed onto the fiber surface, the following evaluation was conducted. A treatment solution (900 ml) identical to that used in Examples 1-4 was prepared, and CNF dispersed and dissolved in the treatment solution was precipitated by electrolysis at 14V for 30 minutes. Furthermore, the same electrolysis treatment was performed on a 900 ml treatment solution equivalent to that used in Examples 1-4, to precipitate CNF remaining in the treatment solution.

[0068] Figure 1A and Figure 1B These are photographs showing the state of CNF precipitated from the treatment solution before and after the above treatment. The CNF precipitated by the above electrolytic treatment was observed as a white turbidity above its respective treatment solution. Figure 1A and Figure 1B As shown, the amount of CNF remaining in the treatment solution after use in the treatment process ( Figure 1B ) and the amount of CNF before processing ( Figure 1A Compared to the above treatment, most of the CNF contained in the treatment solution is adsorbed onto the fabric and removed from the treatment solution.

[0069] Figure 2A and Figure 2B SEM images of the fiber surfaces of the fabric before and after the above treatments (Examples 1-4) are shown. Figure 2B As shown, the fiber surface of fabrics treated in CNF-free water retained the unique surface properties formed during cuprammonium fiber spinning. On the other hand, as... Figure 2A As shown, the fiber surface of the fabric treated in the CNF-containing solution exhibits properties different from those of the cuprammonium fiber described above.

[0070] The surface properties of fibers treated in a solution containing CNF can be understood as the CNF in the solution randomly adsorbing onto the surface of the cuprammonium fiber and becoming integrated, forming a mesh-like coating on the surface of the cuprammonium fiber. Furthermore, the texture observed parallel to the fiber is presumed to be wrinkles that occur when the fiber, adsorbed by CNF under humid conditions, shrinks in volume due to drying, and the adsorbed surface cannot follow the CNF into the fiber interior.

[0071] If we consider that both cuprammonium and CNF are primarily composed of cellulose and have similar densities, then, for example, when CNF is uniformly adsorbed at 0.1–0.5% by weight relative to cuprammonium, the radius of the cuprammonium fiber increases by approximately 0.05%–0.25%, an increase equivalent to the average thickness of the CNF layer on the surface of the cuprammonium fiber. Furthermore, it can be estimated that, relative to... Figure 2A and Figure 2B The cuprammonium fiber shown has an average CNF layer thickness of approximately 2.5 to 12.5 nm when 0.1 wt% to 0.5 wt% CNF is attached. On the other hand, since this estimated average thickness corresponds to the diameter of the CNF used (approximately 3 to 10 nm), it can be inferred that the aforementioned amount of CNF is not uniformly adsorbed onto the surface of the regenerated cellulose fiber to form a coating, but rather that the CNF is adsorbed onto the surface of the regenerated cellulose fiber at predetermined intervals.

[0072] That is, it can be considered that in order to obtain the effect produced by adsorbing CNF on the surface of regenerated cellulose fibers as shown below, it is not necessary to adsorb CNF onto the fiber surface without gaps to form a coating. By adsorbing CNF to the extent that it covers part of the fiber surface, the swelling of the fiber and the degree of shrinkage during subsequent drying can also be reduced.

[0073] For each fabric treated with CNF described above, the degree of shrinkage during the process of immersing the fabric in water to moisten it and then drying it was evaluated using the method described below. The evaluation was conducted as follows: Each fabric marked at 10 cm intervals (two points) was immersed in industrial water at room temperature for approximately 12 hours to allow it to fully absorb water. The interval between the marks was then measured to evaluate the dimensional change during wetting. Next, each fabric was allowed to air dry indoors, and the dimensional change after drying was evaluated by measuring the interval between the marks after drying.

[0074] Table 2 shows the results of the above evaluation. In Table 2, shrinkage during wetting and shrinkage after drying are percentages obtained by dividing the interval between the marked wet and dry areas by 10 cm, respectively. "+" indicates expansion, and "-" indicates shrinkage. As shown in Table 2, it was observed that the fabrics treated with CNF in the above process had a lower degree of expansion when wet compared to the fabric without CNF treatment (Comparative Example 1). Furthermore, in terms of dimensional changes after drying, a significant dimensional reduction was observed in the fabric without CNF treatment (Comparative Example 1), while no substantial dimensional change was observed in the fabric treated with the CNF treatment according to the present invention.

[0075] [Table 2]

[0076]

[0077]

[0078] The differences in swelling behavior of cupro fibers due to the use of and without the CNF treatment described above were evaluated using the methods described below. The evaluation was conducted as follows: the diameter of cupro fibers in the dry state and after immersion in water for 6 hours was measured using a polarizing microscope (Nikon ECLIPSE LOV100N POL, transmission observation under orthogonal Nikkor prisms) for samples without CNF treatment (Comparative Example 1) and samples with CNF treatment (Examples 1-4).

[0079] Table 3 shows the results of the above evaluation. As shown in Table 3, in the fabric without CNF treatment (Comparative Example 1), the cross-sectional area of ​​the fibers swells to about 150% due to water absorption. In contrast, in the fabrics treated with the CNF treatment according to the present invention (Examples 1-4), the degree of swelling is suppressed to about 120%. As shown in Table 3, the reason for suppressing the degree of fiber swelling by performing CNF treatment can be cited as follows: the strong CNF binding around the fiber surface makes it difficult for the swelling due to water content to reach a certain level.

[0080] [Table 3]

[0081]

[0082] For each fabric treated with the above CNF, the tear strength was measured in both dry and wet conditions according to the JIS L 1096D method (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 the fabrics treated with the above CNF, whether in dry or wet conditions.

[0083] [Table 4]

[0084]

[0085]

[0086] Example 2

[0087] The following method is used to treat a cuprammonium fabric (84T / 90F 1630T / M) to allow CNF to be adsorbed onto the surface of the fibers constituting the fabric.

[0088] In the adsorption treatment of fiber surfaces using CNF, a dispersant (manufactured by Meisei Chemical Industry Co., Ltd., ALKOSOL GL) in an amount of 2 wt% relative to the CNF-containing aqueous solution (CELLENPIA, CNF content: 1.0 wt%, hereinafter sometimes referred to as "stock solution 2") manufactured by Nippon Paper Co., Ltd. was added. The resulting solution was diluted with industrial water to a CNF solid content at the weight ratio shown in Table 5 and used as the treatment solution. Furthermore, for "Comparative Example 2" in Table 5, industrial water was used as the treatment solution.

[0089] The processing is carried out as follows: the fabric is immersed in each treatment liquid using a padding treatment device, then pressed with rollers to achieve a wet pick-up of 100% by weight, then dried, and finally fixed (shape stabilization treatment) with hot air at 170°C for about 60 seconds for the following evaluations.

[0090] [Table 5]

[0091]

[0092] For each fabric treated with the above CNF, the degree of shrinkage during the process of immersing it in water to moisten it, as in Example 1, and then drying it was evaluated. The results of the above evaluation are shown in Table 6.

[0093] As shown in Table 6, significant expansion during wetting and shrinkage after drying were observed in Comparative Example 2. In contrast, dimensional changes were suppressed in Examples 2-1 to 2-5, which were treated with CNF.

[0094] [Table 6]

[0095]

[0096]

[0097] Similar to Example 1, the differences in swelling behavior of cupro fibers due to and without the CNF treatment described above were evaluated. The results of the evaluation are shown in Table 7. As shown in Table 7, in the fabric without CNF treatment (Comparative Example 2), the cross-sectional area of ​​the fibers swelled to about 170% due to water absorption. In contrast, in the fabrics treated with the CNF treatment described in this invention (Examples 2-5), the degree of swelling was suppressed to about 116%.

[0098] [Table 7]

[0099]

[0100] For each fabric treated with the above CNF, the tear strength in both dry and wet conditions was measured in the same manner as in Example 1. Table 8 shows the results of these tear strength measurements. As shown in Table 8, no substantial change in tear strength was observed in the fabrics treated with the above CNF, whether dry or wet.

[0101] [Table 8]

[0102]

[0103] Example 3

[0104] The following treatment is performed: For fabrics formed by weaving a checkered pattern from polyester yarn (100 denier) into Bemberg (120 denier) fibers (approximately 35% polyester), the fiber surface of the fabric is covered with CNF pre-mixed with resin components. Bemberg is a regenerated cellulose fiber that tends to shrink after washing, while polyester yarn is a synthetic fiber that does not substantially shrink after washing.

[0105] The treatment solution used in Example 2 as the CNF source was prepared by mixing glyoxal resin (manufactured by DIC Corporation, BECKAMINE N-80) and glyoxal resin (manufactured by DIC Corporation, BECKAMINE M-3) as resin components, a catalyst (manufactured by DIC Corporation, CATALYST 376), and a dispersant (manufactured by Meisei Chemical Industry, Petrox P-200) with industrial water in the proportions shown in Table 9. The fabric was immersed in the treatment solution using a padding device, then rolled to achieve a wet pick-up rate of 100% by weight. After drying, it was cured with hot air at 170°C for approximately 60 seconds while still shaped for evaluation. The evaluation was conducted as follows: the treated and untreated fabrics were subjected to hand washing tests at 40°C and boiling tests at 100°C for 10 minutes, respectively, and the shrinkage rate after drying was evaluated.

[0106] [Table 9]

[0107]

[0108] 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 pre-set markers at 10cm intervals. As shown in Table 10, the untreated fabric shrank by approximately 5% during hand washing and approximately 10% during boiling; in contrast, this shrinkage was significantly suppressed in the CNF-treated fabric. In the untreated fabric with high shrinkage, wrinkles were observed formed by the polyester yarns, which did not shrink substantially, bulging out of the fabric.

[0109] [Table 10]

[0110]

[0111] Example 4

[0112] The tear strength of a cupro fabric (warp: 56T / 60 2000S, weft: 84T901630SZ) was investigated using the following methods, considering CNF adsorption treatment on the fiber surface and further resin processing.

[0113] CNF adsorption treatment: Under the same conditions as in Example 1-1, the above fabric was subjected to high-pressure impregnation with CNF, then dried, and then fixed with hot air at 170°C for about 60 seconds (Example 4-1).

[0114] Resin processing: The fabric that has undergone the CNF adsorption treatment described above (Example 4-1) is further impregnated with a treatment liquid containing 0.5 wt% glyoxal resin (manufactured by DIC Corporation, BECKAMINE N-80; 1 wt%, BECKAMINE M-3; 1 wt%), a catalyst (manufactured by DIC Corporation, CATALYST 376; 0.5 wt%), and CNF derived from the original solution 1. After being rolled and wet-picked to 100% by weight, it is dried and then subjected to the same curing treatment as described above (Example 4-2).

[0115] Table 11 compares the tear strength (dry) of Examples 4-1 and 4-2, measured using the same method as Example 1, with that of the untreated fabric (Comparative Example 4). As shown in Table 11, it was observed that the tear strength was improved by further resin processing of the fabric treated with CNF adsorption.

[0116] [Table 11]

[0117]

[0118] Example 5

[0119] As a means of using CNF pre-mixed with resin components and adsorbing CNF onto fabric (fiber), in order to verify the difference in effect when using high-pressure dyeing and padding, a study was conducted using a fabric (Tanaka & Co. TNK-471-A) with warp yarn: diacetate (AC: 75d S800T / M), weft yarn: cuprammonium (Cu: SB 60 / -) and a mixing ratio of AC 70% / Cu 30% was conducted using the method shown below.

[0120] In the high-pressure impregnation process, glyoxal resin (manufactured by DIC Corporation, BECKAMINE N-80) and glyoxal resin (manufactured by DIC Corporation, BECKAMINE M-3), as well as a catalyst (manufactured by DIC Corporation, CATALYST 376), were mixed in the stock solution 1 used as the CNF source in Example 1 at the proportions shown in Table 12, and industrial water was added to prepare a 300 ml solution for use as a treatment solution. The treatment was performed by sealing a 10 g piece of fabric in the treatment solution (300 ml) in a metal container, heating it to 100°C and maintaining it for 20 minutes (high-pressure impregnation process). The treated fabric was dried at room temperature and then cured with hot air at 170°C for 60 seconds (Example 5-1). In addition, for comparison, samples treated in the same manner as above were prepared (Comparative Example 5), except that industrial water was used as the treatment solution.

[0121] [Table 12]

[0122]

[0123] Furthermore, the padding process was performed as follows: using the stock solution 1 used in Example 1 as the CNF source, a solution formed by mixing glyoxal resin (manufactured by DIC Corporation, BECKAMINE N-80), glyoxal resin (manufactured by DIC Corporation, BECKAMINE M-3), and catalyst component (manufactured by DIC Corporation, CATALYST 376) with industrial water in the proportions shown in Table 13 was used as the treatment solution. In addition, in order to eliminate the influence of the hydrothermal treatment in Example 5-1 on the fibers, the fabric obtained in Comparative Example 5 above was subjected to padding processing as a sample (Example 5-2).

[0124] [Table 13]

[0125]

[0126] Table 14 shows the results of tear strength measurements in the dry state for Examples 5-1, 5-2, and Comparative Example 5, taken using the same method as in Example 1. As shown in Table 14, from the viewpoint of treated tear strength, CNF treatment via padding significantly improves tear strength. It is speculated that this result is due to changes in the morphology of CNF adsorbed on the fiber and the state of the resin, depending on the treatment method used when CNF covers the fiber.

[0127] [Table 14]

[0128]

[0129]

[0130] Industrial availability

[0131] According to the present invention, by adsorbing CNF and the like onto regenerated cellulose fibers, shrinkage of the regenerated cellulose fibers and the like during washing or other processes can be suppressed.

Claims

1. A method for preventing shrinkage of regenerated cellulose fibers, characterized in that, The shrinkage prevention treatment method includes: In the cellulose nanofiber adsorption process, a fabric containing regenerated cellulose fibers is sealed in a container in a cellulose nanofiber dispersion containing more than 0.001 wt% of the cellulose nanofibers and glyoxal resin, and then heated for high-pressure dyeing, so that the regenerated cellulose fibers adsorb the adsorbent containing the cellulose nanofibers. In a drying process, the regenerated cellulose fibers that have adsorbed the adsorbent containing the cellulose nanofibers are dried such that the weight percentage of the cellulose nanofibers is 0.05 wt% to 5 wt% of the total regenerated cellulose fibers; and The shape stabilization process, which follows the drying process, involves heating the regenerated cellulose fibers containing the adsorbent, which are adsorbed with the cellulose nanofibers, to 150°C to 200°C for shape stabilization.

2. The shrinkage prevention treatment method for regenerated cellulose fibers according to claim 1, characterized in that, The cellulose nanofiber dispersion contains a surfactant or orange oil as a dispersant.

3. The shrinkage prevention treatment method for regenerated cellulose fibers according to claim 1, characterized in that, The cellulose nanofiber dispersion contains any one of sodium hydroxide, soda ash, oxalic acid, acetic acid, and malic acid.

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