JP2019178433A - Modified cellulose fiber - Google Patents

Abstract

To provide a modified cellulose fiber that has a high hygroscopicity, a high deodorant property and a high washing durability.SOLUTION: The modified cellulose fiber according to the present invention is obtained by graft-polymerizing a vinyl monomer to a cellulose-based fiber and has a microvoid in the inside of the fiber, and in which, the area ratio of the microvoid in a cross section perpendicular to the fiber length direction is 0.01% or more and 5.00% or less.SELECTED DRAWING: Figure 1-2

Description

  The present invention relates to a modified cellulose fiber in which a vinyl monomer is graft-polymerized on a cellulosic fiber.

  Conventionally, many methods have been proposed in which vinyl monomers are graft-polymerized on cellulose fibers such as cotton, hemp and rayon to improve the hygroscopicity and deodorant properties of the cellulose fibers. Cellulosic fibers are widely used, for example, in general clothing applications. However, in recent years, further improvements in functionality have been demanded by consumers.

  In order to meet such a demand for improving functionality, for example, Patent Document 1 discloses a fiber obtained by graft polymerization of a polymerizable vinyl monomer using radiation graft polymerization. Patent Document 2 discloses a grafting process including a polymerization process in which a monomer having a polymerizable group is graft-polymerized to the cellulose fiber in the presence of a water-soluble radical generator and a dispersing agent in an aqueous dispersion of cellulose fiber. A method for producing polymer-modified cellulose fibers is disclosed. Furthermore, Patent Document 3 discloses a hygroscopic cellulose comprising a step of irradiating natural cellulose fibers with an electron beam, a step of bringing a compound containing a carboxylic acid group into contact with the fibers and chemically bonding them, and a mercerizing process with an alkaline aqueous solution. A method for producing a fiber is disclosed.

JP 2002-339187 A JP 2013-234283 A JP 2014-133963 A

  However, in the method described in Patent Document 1, since radiation graft polymerization is used, not only the process is troublesome, such as repeating degassing and nitrogen purging before irradiation, but also handling of various types of radiation requires attention. It is not suitable for commercial production because qualified personnel are required for operation. Furthermore, in the method described in Patent Document 1, since the polymerization reaction of the polymerizable vinyl monomer proceeds preferentially on the fiber surface, it is difficult to carry out the modification at a higher level.

  In addition, in the method described in Patent Document 2, since polyvinyl pyrrolidone is used as a dispersant, the preparation liquid not only thickens, but also hardens into a film after drying, which is preferable as a modified fiber for clothing use. Absent. Moreover, since the polymerization reaction preferentially proceeds on the fiber surface in the method described in Patent Document 2, it is difficult to carry out the modification at a higher level.

  Furthermore, in the method described in Patent Document 3, it is necessary to use high concentration sodium hydroxide in order to promote mercerization of natural cellulose fibers (especially cotton). However, hydrolysis of the graft chain proceeds. Therefore, the fiber surface is gelled, and the washing durability of the fiber is poor.

  Under such circumstances, in the present invention, the provision of a modified cellulose fiber having high hygroscopicity, high deodorizing property, and high washing durability is listed as an object of the invention.

  As a result of intensive studies to solve the above problems, the present inventors have obtained a modified cellulose fiber in which a vinyl monomer is graft-polymerized on a cellulosic fiber, has a microvoid inside the fiber, and the length of the fiber. The present invention has been completed by finding that the above-mentioned problems can be solved if the modified cellulose fiber has an area ratio of the microvoids in a cross section perpendicular to the direction of 0.01% to 5.00%.

That is, the modified cellulose fiber according to the present invention has the gist in the following points.
[1] A modified cellulose fiber obtained by graft-polymerizing a vinyl monomer to a cellulosic fiber,
Have microvoids inside the fiber,
A modified cellulose fiber, wherein the area ratio of the microvoids in a cross section perpendicular to the length direction of the fiber is 0.01% or more and 5.00% or less.
[2] The modified cellulose fiber according to [1], wherein an official moisture content measured according to JIS L 0105 5-6 (2015) is 12.0% or more and 20.0% or less.
[3] The modified cellulose fiber according to [1] or [2], wherein the ammonia odor component reduction rate measured based on the following method is 80.0% or more and 100% or less.
<Ammonia odor component reduction rate>
Ammonia odor of modified cellulose fiber in accordance with “21. Deodorization test” of “SEK Mark Textile Product Certification Criteria (revised on April 1, 2017)” stipulated by the Japan Fiber Evaluation Technology Council The component reduction rate is measured. In the measurement, the test sample size is 0.3 g, and the measurement time (standing time) is 20 minutes. In addition, the ammonia odor component generation method uses a permeator to evaluate the ammonia odor component reduction rate by a detection tube method using a modified cellulose fiber that has been conditioned and humidified at 20 ° C. and 65% RH for 24 hours or more. The initial concentration of the ammonia odor component is 100 mg / kg.
[4] The modified cellulose fiber according to any one of [1] to [3], wherein the fiber cross section does not have a skin core structure.
[5] The modified cellulose fiber according to any one of [1] to [4], wherein the vinyl monomer is a monomer having a vinyl group and a carboxy group.
[6] The modified cellulose fiber according to any one of [1] to [5], wherein the vinyl monomer is acrylic acid, methacrylic acid, or maleic acid.

  ADVANTAGE OF THE INVENTION According to this invention, the modified cellulose fiber which has high hygroscopicity, high deodorizing property, and high washing durability is provided.

FIG. 1-1 is a cross-sectional photograph (magnification: 2000 times) of a cellulosic fiber before modification having microvoids inside the fiber. FIG. 1-2 is a cross-sectional photograph (magnification: 2000 times) of a modified cellulose fiber having microvoids inside the fiber. FIG. 2-1 is a cross-sectional photograph (magnification: 5000 times) of a cellulosic fiber before modification that does not have microvoids inside the fiber. FIG. 2-2 is a cross-sectional photograph (magnification: 5000 times) of the modified cellulose fiber having no microvoids inside the fiber.

<Modified cellulose fiber>
The modified cellulose fiber according to the present invention is a modified cellulose fiber obtained by graft-polymerizing a vinyl monomer to a cellulosic fiber, and has a microvoid inside the fiber. The presence of microvoids inside the fiber allows the vinyl monomer to diffuse faster at the site where the microvoids are present, and the graft polymerization proceeds even inside the cellulosic fiber, resulting in a higher grafting rate and higher than before. The modified cellulose fiber has a high official moisture content and a high ammonia odor component reduction rate. Further, the graft polymerization also proceeds inside the modified cellulose fiber, so that the washing durability of the modified cellulose fiber is also improved.

  In the present specification, the term “microvoid” refers to a cavity having an inner diameter of 50 to 300 nm existing in a fiber (however, the cavity contains a polymer produced by grafting), and the cavity has a long diameter in a fiber cross section. Is confirmed by a circular object of 50 to 300 nm (in many cases, an ellipse). FIG. 1-2 shows a cross-sectional photograph (magnification: 2000 times) of the modified cellulose fiber having microvoids inside the fiber. As shown in FIG. 1-2, the microvoids are preferably present in a substantially uniformly dispersed manner inside the fiber. Moreover, as shown to FIGS. 1-2, it is a more preferable aspect that a micro void exists more in a fiber center part compared with a fiber surface layer part inside a fiber.

  In the modified cellulose fiber, the area ratio of the microvoids in a cross section perpendicular to the length direction of the fiber is 0.01% or more, more preferably 1.00% or more, and further preferably 1.50% or more, Preferably it is 5.00% or less, More preferably, it is 4.50% or less, More preferably, it is 4.00% or less. If the area ratio of the microvoids is below the above range, graft polymerization inside the modified cellulose fiber is not sufficient, and there is a possibility that the desired high hygroscopicity, high deodorizing property, and high washing durability may not be obtained. It is not preferable. On the other hand, when the area ratio of the microvoids exceeds the above range, although the modification is promoted, the breaking strength of the modified cellulose fiber is lowered, so that the fiber cannot withstand actual use.

  It is a preferred embodiment that the modified cellulose fiber does not have a skin core structure in the fiber cross section. In this specification, “does not have a skin core structure” means that there is no skin core structure in the fiber cross section observed by carbon deposition after dyeing an ultrathin section of fiber in ruthenium tetroxide vapor for 30 minutes. Say. In general, many cellulose fibers, particularly cellulose fibers obtained by a wet spinning method such as viscose rayon, have a clear skin core structure. Amorphous portions tend to be formed more in the skin portion (that is, the fiber surface layer portion), and crystal portions tend to be formed more in the core portion (that is, the fiber center portion). If the boundary between the amorphous part and the crystal part is clear, the modification proceeds mainly with respect to the amorphous part, and the properties of the modified cellulose fiber are greatly different between the skin part and the core part. Then, since it becomes difficult to exhibit the desired high hygroscopicity, high deodorizing property, and high washing durability, the modified cellulose fiber according to the present invention may not have a clear boundary between the skin portion and the core portion. desirable. The fact that the modified cellulose fiber does not have a skin core structure in the cross section of the fiber means that the vinyl monomer easily penetrates and diffuses into the inside of the cellulosic fiber, and the modification is substantially inside the fiber. It means to reach.

  The reason for using ruthenium tetroxide is that ruthenium tetroxide causes ruthenium tetroxide to be introduced in the amorphous part of the fiber crystalline polymer, so that ruthenium tetroxide is introduced. This is to utilize the fact that electron beam contrast is formed.

  The official moisture content measured according to JIS L 0105 5-6 (2015) of the modified cellulose fiber according to the present invention is preferably 12.0% or more, more preferably 13.0% or more, and still more preferably 15 0.0% or more, more preferably 17.0% or more, preferably 20.0% or less, and may be 19.0% or less. Since the modified cellulose fiber of the present invention has microvoids, the official moisture content can be made higher than that of the conventional one. On the other hand, in the range where the official moisture content significantly exceeds the upper limit, there is a concern that the reforming progresses too much and the mechanical strength of the modified cellulose fiber decreases, and the production cost increases, New problems may arise, such as concerns about safety such as residual unreacted monomers.

The ammonia odor component reduction rate measured based on the following method of the modified cellulose fiber according to the present invention is preferably 80.0% or more, more preferably 88.0% or more, and further preferably 92.0% or more. The upper limit is not particularly limited, but is preferably 100% or less and may be 98.0% or less. Since the modified cellulose fiber of the present invention has microvoids, the ammonia odor component reduction rate can be further increased as compared with the conventional one.
<Ammonia odor component reduction rate>
Ammonia odor of modified cellulose fiber in accordance with “21. Deodorization test” of “SEK Mark Textile Product Certification Criteria (revised on April 1, 2017)” stipulated by the Japan Fiber Evaluation Technology Council The component reduction rate is measured. In the measurement, the test sample size is 0.3 g, and the measurement time (standing time) is 20 minutes. In addition, the ammonia odor component generation method uses a permeator to evaluate the ammonia odor component reduction rate by a detection tube method using a modified cellulose fiber that has been conditioned and humidified at 20 ° C. and 65% RH for 24 hours or more. The initial concentration of the ammonia odor component is 100 mg / kg.

  The graft ratio of the modified cellulose fiber is preferably 11.0% or more, more preferably 13.0% or more, still more preferably 15.0% or more, still more preferably 20.0% or more, and particularly preferably 23.%. Although it is 0% or more and an upper limit is not specifically limited, Generally it is 40.0%. Since the modified cellulose fiber of the present invention has microvoids, the graft rate can be increased as compared with the conventional one. The method for measuring the graft ratio will be described in detail in the Examples section.

  In addition, the modified cellulose fiber according to the present invention includes matting agents (dull agents) such as titanium dioxide, barium sulfate, silicon dioxide, and kaolinite; organic pigments; inorganic pigments; An additive such as an antioxidant may be contained. The addition of the additive to the modified cellulose fiber may be performed by appropriately using a known method such as mixing of the cellulose fiber into a spinning dope, an exhaust method, a pad method, and the like.

  The fineness of the modified cellulose fiber is not particularly limited, and is preferably 0.5 to 5.0 dtex, more preferably 0.6 to 4.0 dtex, and still more preferably 0.3 to 3.0 dtex.

  The modified cellulose may be long fibers or short fibers, but short fibers are preferable, and the fiber length is preferably 10 to 60 mm, more preferably 20 to 50 mm.

  The cross-sectional shape of the modified cellulose is not particularly limited, and may be either a round cross section or a modified cross section. Examples of the atypical cross section include a polygonal cross section such as a triangle; a multi-leaf cross section such as a Y shape, a cross, a six leaf, and an eight leaf;

<Method for producing modified cellulose fiber>
The modified cellulose fiber according to the present invention is produced by graft polymerization of a vinyl monomer to a cellulosic fiber.

  The cellulosic fiber is preferably a cellulosic fiber having microvoids inside the fiber. If microvoids are present inside the fiber at the raw cotton stage, the graft polymerization can proceed even inside the fiber during the graft polymerization. FIG. 1-1 shows a cross-sectional photograph (magnification: 2000 times) of a cellulosic fiber before modification having microvoids inside the fiber. As shown in FIG. 1-1, microvoids may exist in a substantially uniformly dispersed manner inside the fiber, and in particular, in the inside of the fiber, the microvoid should be present more in the fiber center than in the fiber surface layer. Is a preferred embodiment. On the other hand, FIG. 2-1 shows a cross-sectional photograph (magnification: 5000 times) of a cellulosic fiber before modification without microvoids inside the fiber. In the case of cellulosic fibers that do not have microvoids inside the fibers, graft polymerization may proceed only at the surface layer of the fibers, and a high graft ratio may not be achieved.

  Cellulosic fibers are preferably regenerated cellulose fibers such as high wet modulus (HWM) rayon such as modal and polynosic, viscose rayon, cupra and tencel (Lyocell). Microvoids are easily formed at the interface between a polymer and fine particles typified by a catalyst, a matting agent, and the like when producing cellulosic fibers.

  In particular, in the regenerated cellulose fiber produced by the wet spinning method, microvoids tend to be formed during the liquid-liquid exchange reaction between the cellulose-dissolving solution and the coagulation liquid. Therefore, the raw cotton may contain microvoids. Selection of regenerated cellulose fibers produced by a high wet spinning method is desirable. As such a regenerated cellulose fiber, HWM rayon is particularly preferable. HWM rayon is a kind of modified rayon, and is characterized by a higher wet strength than rayon. Specifically, the tensile strength of the HWM rayon (staple) when wet is 2.3 to 3.7 cN / dtex.

  The average degree of polymerization of the regenerated cellulose fiber is not particularly limited, and is preferably 300 to 600, more preferably 350 to 550.

  Although it will not specifically limit if it is a monomer which has a vinyl group as a vinyl monomer, Preferably it is a monomer which has a vinyl group and a carboxy group. Examples of the monomer having a vinyl group and a carboxy group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, butenetricarboxylic acid, and derivatives thereof, preferably acrylic acid, methacrylic acid or maleic acid. Yes, more preferably acrylic acid or methacrylic acid. Each of these can be used alone or in a mixture of two or more for graft polymerization. In the graft polymerization, a hydrophilic monomer typified by acrylamide or a derivative thereof, or a hydrophobic monomer typified by styrene or methyl (meth) acrylate may be copolymerized to such an extent that the object of the present invention is not impaired. Is possible.

  The amount of the vinyl monomer used is not particularly limited, but is preferably 5 to 50% o.d. w. f, more preferably 10-40% o. w. f. The graft ratio tends to increase as the amount of vinyl monomer used increases.

  At the time of graft polymerization, various auxiliary agents for the purpose of promoting the reaction and stabilizing the quality may be used as necessary. Examples of the auxiliary agent include a polymerization initiator, a metal ion sealing agent (chelating agent), a pH adjuster (for example, sulfuric acid, sodium carbonate, etc.), a dispersing agent, a cellulose fiber swelling agent, and the like.

  Examples of the polymerization initiator include peroxides such as benzoyl peroxide, potassium persulfate, and ammonium persulfate; azo compounds such as azobisisobutyronitrile; redox initiators; and the like. In particular, in redox initiators, divalent iron salts capable of releasing divalent iron ions in water, such as iron (II) sulfate, iron (II) chloride, iron (II) ammonium sulfate, iron (II) nitrate, etc. And a method of reacting hydrogen peroxide to generate a hydroxy radical is preferably used because the graft copolymerization can proceed under relatively low temperature conditions.

  Examples of the metal ion sealing agent include condensed phosphates such as sodium pyrophosphate, sodium triphosphate, sodium trimetaphosphate, sodium tetrametaphosphate, sodium polyphosphate, disodium salt of ethylenediaminetetraacetic acid, and 3 of ethylenediaminetetraacetic acid. Examples thereof include sodium salts, ethylenediaminetetraacetic acid tetrasodium salt, ethylenediaminetetraacetic acid diammonium salt, ethylenediaminetetraacetic acid tetraammonate, and other ethylenediaminetetraacetic acid salts, and nitrilotriacetic acid such as nitrilotriacetic acid disodium salt.

  When carrying out the graft polymerization, the form of the cellulosic fiber may be any of a fibrous form, a thread form, a woven form, a knitted form, and a non-woven form. When graft polymerization is performed in a fibrous state, it is preferable to advance the modification after removing the oil agent on the fiber surface by scouring. In addition, after the modification, an antistatic agent and a friction inhibitor may be appropriately added to the modified cellulose fiber in consideration of the spinning property after the spinning step. Similarly, in the case of graft polymerization in a yarn state, an antistatic agent, a friction inhibitor, a bundling agent, and a smoothing agent are appropriately added to the modified yarn in consideration of the subsequent weaving process and knitting process. May be.

  When graft polymerization is performed in a fibrous state, it is desirable from the viewpoint of achieving a stable graft ratio to perform the graft polymerization in a high-pressure sealed container such as an Overmeier dyeing machine. In the overmeyer dyeing machine, it is desirable to replace the air in the container with an inert gas such as nitrogen. Furthermore, after charging the high-pressure container, the air in the container is replaced with an inert gas such as nitrogen. It is good to leave. In the case of overmeier treatment, the reaction proceeds more evenly, so the modifying agent can be supplied to the over dyeing machine alternately from the inside to the outside (in-out) and from the outside to the inside (out-in). desirable.

  The modified cellulose fiber after graft polymerization may be appropriately subjected to alkali metal chloride. In particular, when the vinyl monomer is a monomer having a carboxy group, the hygroscopic performance is enhanced by alkali metal chloride replacing a hydrogen atom in the carboxy group with a metal ion (particularly a cation). Examples of the metal ions include alkali metal ions such as sodium ions and potassium ions; alkaline earth metal ions such as calcium ions and magnesium ions. These metal ions may be used alone or in combination of two or more. Moreover, it is good to use the salt containing the said metal ions, such as sodium carbonate (soda ash), for the treatment of alkali metal chloride.

<Use of modified cellulose fiber>
Since the modified cellulose fiber according to the present invention has both high hygroscopicity and high deodorizing properties, it can be preferably applied to apparel applications such as sports shirts and innerwear. In particular, since the modified cellulose fiber has excellent washing durability, it can continuously enjoy high hygroscopicity and high deodorizing property until the product lifetime. Moreover, since the ammonia odor component reduction rate of the modified cellulose fiber according to the present invention is good, it exhibits excellent performance not only for clothing but also for household materials, interiors, pet goods and the like.

  The form of the fiber product using the modified cellulose fiber according to the present invention may be any of a fibrous form, a thread form, a woven form, a knitted form, and a non-woven form. In addition, textile products using the modified cellulose fibers according to the present invention were dyed such as clothing, bedding, interior goods, and other small articles sewn using woven fabrics, knitted fabrics, nonwoven fabrics, etc. containing modified cellulose fibers. Products are also included.

  The mixing ratio of the modified cellulose fiber to the fiber product is preferably 5 to 100% by mass, and more preferably 15 to 90% by mass with respect to the entire fiber mass. When the mixing ratio is lower than the lower limit value, the effect of the modified cellulose fiber hardly appears in the fiber product.

  In the fiber product, as components other than the modified cellulose fiber, polyester fibers such as polyethylene terephthalate fiber, polybutylene terephthalate fiber and polylactic acid fiber; polyamide fibers such as nylon 6 and nylon 66; rayon, polynosic, cupra, lyocell, etc. Regenerated fibers; semi-synthetic fibers such as acetate fibers and triacetate fibers; natural fibers such as cotton and hemp may be included. These fibers may be either modified or unmodified.

Since the modified cellulose fiber according to the present invention is excellent in high hygroscopicity, for example, the mixing ratio of the modified cellulose fiber is 5 to 50% by mass (preferably 10 to 40% by mass, based on the entire fiber mass, If the textile product is preferably cotton), the remainder of the textile product is preferably 12.0-20.0%, more preferably 13.0-18.0% when not washed. Official moisture content can be achieved. Further, the official moisture content of the textile product after washing 10 times is preferably 10.0 to 18.0%, more preferably 13.0 to 17.0%.
In particular, since the modified cellulose fiber according to the present invention has high washing durability, the change rate of the official moisture content of the textile product after washing 10 times, preferably 15.0% or less, more Preferably, it can be suppressed to 10.0% or less, more preferably 5.0% or less. The rate of change in the official moisture content of the textile after the tenth washing can be calculated based on the following formula (c).
Change rate of official moisture content of textile products after 10 washings (%)
= {(M0−M10) / M0} × 100 (c)
[In the formula (c),
M0 is the official moisture content of the textile when not being washed,
M10 represents the official moisture content of the textile product after 10 washes. ]
In addition, the procedure regarding the measurement of the official moisture content of a textile product and washing | cleaning is the same as that of the case of the dyed fabric described in an Example.

Moreover, since the modified cellulose fiber which concerns on this invention is excellent in high deodorizing property, the mixing rate of the said modified cellulose fiber is 5-50 mass% (preferably 10-40 mass) with respect to the whole fiber mass, for example. %, Preferably 90.0 to 100.0%, more preferably 95.0 to 100.0% unwashed, if it is a textile product (preferably knitted), the remainder of the textile product is preferably cotton) It is possible to achieve the ammonia odor component reduction rate at the time. Furthermore, the ammonia odor component reduction rate of the textile product after 10 washings is preferably 80.0 to 100.0%, more preferably 90.0 to 98.0%.
In particular, since the modified cellulose fiber according to the present invention has high washing durability, the rate of change in the ammonia odor component reduction rate of the textile product after washing 10 times, preferably 14.0% or less , More preferably 10.0% or less, still more preferably 5.0% or less. The rate of change in the ammonia odor component reduction rate of the textile after the tenth washing can be calculated based on the following formula (d).
Change rate of decrease rate of ammonia odor component of textile after 10 times of washing (%)
= {(S0−S10) / S0} × 100 (d)
[In the formula (d),
S0 is the rate of change of the ammonia odor component reduction rate of the textile product when not being washed,
S10 represents the rate of change of the ammonia odor component reduction rate of the textile product after 10 washes. ]
In addition, the procedure regarding the measurement of the change rate of the ammonia odor component reduction rate of the textile product and the washing is the same as in the case of the dyed fabric described in the examples.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.

<Presence / absence of microvoids / area ratio of microvoids / presence / absence of skin core structure>
(1) Preparation of sample A fiber to be measured is embedded in an epoxy resin, and an ultrathin section is prepared using a microtome equipped with an ultrasonic knife. Next, the ultrathin slice is dyed in ruthenium tetroxide vapor for 30 minutes and then subjected to carbon vapor deposition. The obtained sample is used as a measurement sample.
(2) Cross-sectional observation Cross-sectional observation and photography are performed using the measurement sample prepared in (1) and a transmission electron microscope ("JEM-2100" manufactured by JEOL Ltd., acceleration voltage 200 kV). The presence or absence of microvoids and the presence or absence of a skin core structure are confirmed by cross-sectional observation.

Further, the area ratio of the microvoids in the cross section perpendicular to the fiber length direction is obtained by image analysis of the cross-sectional photograph. The area ratio can be calculated based on the following formula (a).
Area ratio of microvoids in the cross section perpendicular to the longitudinal direction of the fiber (%)
= (Cross-sectional area of microvoids / cross-sectional area of fibers) × 100 (a)
For the calculation of the area ratio, five different fiber samples are arbitrarily extracted, measurement is performed at one arbitrary measurement point for each, and an average value of the five values is used. When calculating the area ratio, the total area of the fiber cross section bordered by the fiber contour is adopted as the cross sectional area of the fiber, and the micro void (FIG. 1-2, etc.) confirmed in the fiber cross section is used as the cross sectional area of the micro void. The total area of the part that appears white in the figure is adopted.
An example of a cross-sectional photograph (magnification: 2000 times) of the modified cellulose fiber having microvoids inside the fiber is shown in FIG. As shown in FIG. 1-2, since the microvoid 1 is confirmed by a circular object having a major axis of 50 to 300 nm (in many cases, an ellipse) in the fiber cross section, when determining the cross sectional area of the microvoid, 50 nm The cross-sectional area of a circular object having a diameter less than 300 nm or more than 300 nm is not included in the total area of microvoids. Depending on conditions, not only microvoids 1 but also cracks / strains 3 may be confirmed in the cross section of the fibers 2. Although the embedding process with the epoxy resin 4 is performed in a sufficiently degassed environment, it is technically difficult to completely embed the process without removing the bubbles. A large cavity with a major axis exceeding 300 nm may be observed. In this case, the area of the portion observed as the crack / strain 3 is included in the cross-sectional area of the fiber but is not included in the cross-sectional area of the microvoid.

<Graft ratio>
The graft ratio is calculated from the mass increase rate of the fiber mass (W1) after modification with respect to the fiber mass (W0) before modification based on the following formula (b). The graft ratio is evaluated by preparing six samples in which about 30 g of cellulosic fibers before modification are encapsulated and using the average value of these six samples. The fiber mass is measured after drying the fiber to be measured at 110 ° C. and then adjusting the temperature and humidity for 24 hours under the conditions of a temperature of 20 ° C. and a relative humidity of 65%.
Graft rate (%) = {(W1-W0) / W0} × 100 (b)

<Official moisture content>
According to JIS L 0105 5-6 (2015), the official moisture content of the modified cellulose fiber (6.1 “fibrous sample”) and dyed cloth (6.3.2 “for knitted fabric”) is measured. To do.
“Unwashed” is the result when a dyed fabric before washing is used as a sample.
“After washing 10 times” means that the dyed cloth obtained by repeating washing (specifically washing-dehydrating-hanging drying) 10 times on the dyed cloth obtained in Examples and Comparative Examples is a sample. This is the result. Washing-dehydration is performed according to No. stipulated in Annex F using a C-type standard washing machine-vertical shaft / upper charging type (pulsator type). The drying is performed based on the C4M method, and the hanging drying is performed based on the method 10.1.1 A-hanging drying.

<Ammonia odor component reduction rate>
Modified cellulose fiber and dyeing processing according to “21. Deodorization test” of “SEK Mark Textile Product Certification Criteria (revised on April 1, 2017)” prescribed by the Japan Fiber Evaluation Technology Council Measure the ammonia odor component reduction rate of the fabric. In the measurement, the test sample size is 0.3 g for the modified cellulose fiber and 1.0 g for the dyed fabric, and the measurement time (standing time) is 20 minutes for the modified cellulose fiber and 2 hours for the dyed fabric. . In addition, the ammonia odor component generation method uses a permeator (“Permeator PD-1B-2” manufactured by GASTECH), modified cellulose fiber or dyed cloth that has been conditioned and humidified at 20 ° C. and 65% RH for at least 24 hours. Using the detector tube method, the ammonia odor component reduction rate is evaluated. The initial concentration of the ammonia odor component is 100 mg / kg.
“Unwashed” is the result when a dyed fabric before washing is used as a sample.
“After washing 10 times” means that the dyed cloth obtained by repeating washing (specifically washing-dehydrating-hanging drying) 10 times on the dyed cloth obtained in Examples and Comparative Examples is a sample. This is the result. Washing-dehydration is performed according to No. stipulated in Annex F using a C-type standard washing machine-vertical shaft / upper charging type (pulsator type). The drying is performed based on the C4M method, and the hanging drying is performed based on the method 10.1.1 A-hanging drying.

Example 1
Cellulosic fiber (viscose rayon bright staple fiber: “Modal (registered trademark)” manufactured by Lenzing Co., Ltd., 1.0 dtex, 39 mm cut) is used in accordance with a conventional method using a high-pressure overmeier dyeing machine (manufactured by Nisaka Seisakusho). After scouring and washing with water at a bath temperature of 70 ° C., a graft polymerization treatment was performed at a treatment temperature of 80 ° C. with the drug formulation shown in Table 1 (unit:% owf (on the weight of fiber)). A modified cellulose fiber was prepared.

  The obtained modified cellulose fibers and cotton were blended with cotton so that the mass fractions would be 30% and 70%, respectively, under the standard conditions defined in JIS L 0105 5.1.1 (2015). A spun yarn with an English cotton count of 40 was obtained by a known ring spinning method.

  100% of the obtained spun yarn is used and knitted into a tengu structure, then subjected to scouring, cotton bleaching using hydrogen peroxide and soda ash (sodium carbonate), and dyeing with a reactive dye to obtain a dyed fabric It was.

Examples 2-3
A modified cellulose fiber and a dyed cloth were obtained by the same method as in Example 1 except that the drug formulation in the graft polymerization treatment was changed as shown in the table.

Comparative Example 1
A modified cellulose fiber and a dyed cloth were obtained in the same manner as in Example 1 except that cellulosic fiber (staple fiber: “Tencel (registered trademark)” manufactured by Lenzing, 1.3 dtex, 38 mm cut) was used. Obtained. In addition, the cross-sectional photograph of the cellulosic fiber before the graft polymerization treatment is shown in FIG. 2-1, and the cross-sectional photograph of the modified cellulose fiber after the graft polymerization treatment is shown in FIG.

Comparative Example 2
A modified cellulose fiber and a dyed cloth were obtained in the same manner as in Example 3 except that cellulosic fibers (staple fibers: “Lyocell (registered trademark)” manufactured by Lenzing, 0.9 dtex, 38 mm cut) were used. Obtained.

As shown in Table 1, all the modified cellulose fibers obtained in Examples 1 to 3 had microvoids. On the other hand, the modified cellulose fibers obtained in Examples 1 to 3 did not have a skin core structure. Moreover, all graft ratios were high compared with Comparative Examples 1-2, and the official moisture content and the ammonia odor component reduction rate showed the favorable result. In particular, the ammonia odor component reduction rate of the modified cellulose fiber is evaluated in a shorter time than the measurement time defined in the “SEK Mark Fiber Product Certification Criteria (April 1, 2017 revision)”, but the measurement time The ammonia odor component reduction rate of a certain level or more is exhibited even under the condition where the slag is shortened, and it can be seen how the modified cellulose fiber according to the present invention has excellent immediate deodorizing performance.
In addition, the dyed fabric including the modified cellulose fiber according to the present invention has both a soft touch and appropriate water absorption / deodorant properties. In particular, even after 10 washes, the official moisture content and ammonia odor component reduction rate were maintained high, and it was confirmed that the laundry durability was also excellent.

  On the other hand, since the modified cellulose fiber obtained in Comparative Example 1 does not have microvoids as shown in FIG. 2-2, the official moisture content and the ammonia odor component reduction rate of the modified cellulose fiber itself are insufficient. there were. In addition, the dyed fabric including the modified cellulose fiber obtained in Comparative Example 1 has a high official moisture content and ammonia odor component reduction rate at the time of non-washing, but each value greatly decreases after 10 washings, It was found that the washing durability was poor.

  Moreover, since the modified cellulose fiber obtained in Comparative Example 2 also has no microvoids, the official moisture content and the ammonia odor component reduction rate of the modified cellulose fiber itself were insufficient. Furthermore, the official moisture content and the ammonia odor component reduction rate of the dyed fabric after unwashing and after 10 washes were low and could not withstand actual use.

1 Microvoid 2 Fiber 3 Cracking / Strain 4 Epoxy resin

Claims (6)

It is a modified cellulose fiber in which a vinyl monomer is graft-polymerized on a cellulosic fiber,
Have microvoids inside the fiber,
A modified cellulose fiber, wherein the area ratio of the microvoids in a cross section perpendicular to the length direction of the fiber is 0.01% or more and 5.00% or less.   The modified cellulose fiber according to claim 1, wherein an official moisture content measured according to JIS L 0105 5-6 (2015) is 12.0% or more and 20.0% or less. The modified cellulose fiber according to claim 1 or 2, wherein the ammonia odor component reduction rate measured based on the following method is 80.0% or more and 100% or less.
<Ammonia odor component reduction rate>
Ammonia odor of modified cellulose fiber in accordance with “21. Deodorization test” of “SEK Mark Textile Product Certification Criteria (revised on April 1, 2017)” stipulated by the Japan Fiber Evaluation Technology Council The component reduction rate is measured. In the measurement, the test sample size is 0.3 g, and the measurement time (standing time) is 20 minutes. In addition, the ammonia odor component generation method uses a permeator to evaluate the ammonia odor component reduction rate by a detection tube method using a modified cellulose fiber that has been conditioned and humidified at 20 ° C. and 65% RH for 24 hours or more. The initial concentration of the ammonia odor component is 100 mg / kg.   The modified cellulose fiber according to any one of claims 1 to 3, wherein the fiber cross section does not have a skin core structure.   The modified cellulose fiber according to any one of claims 1 to 4, wherein the vinyl monomer is a monomer having a vinyl group and a carboxy group.   The modified cellulose fiber according to any one of claims 1 to 5, wherein the vinyl monomer is acrylic acid, methacrylic acid or maleic acid.