Method for producing metal carboxylate-grafted cellulose fiber and method for producing moisture-absorbing and heat-generating fiber structure

Abstract

To provide a manufacturing method of carboxylic acid metal salt grafted cellulose fiber, which suppresses carboxyl groups introduced into sliver-like cellulose fiber from turning into alkali metal salts such as Na salts having high affinity with water.SOLUTION: A manufacturing method of carboxylic acid metal salt grafted cellulose fiber includes: a grafting step of grafting a carboxyl group-containing compound containing ethylenic unsaturated double bonds onto a sliver-like cellulose fiber to introduce carboxyl groups; and a blocking step of bringing the grafted cellulose fibers into contact with a treatment liquid containing at least one metal ion selected from Ca, Mg, and Zn to convert the carboxyl groups into metal salts thereof.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a metal carboxylate-grafted cellulosic fiber and a method for producing a moisture-absorbing and heat-generating fiber structure. [Background technology]

[0002] Hygroscopic heat generation is the property of dry fibers that generate heat when they absorb moisture (water). For example, if you bring a futon that has been exposed to the sun during the day into a room, even if it has cooled to the same temperature as the room after a few hours, it will still feel warm when you put your skin against it.

[0003] The present applicant has proposed a method for imparting moisture-absorbing and heat-generating properties to cellulosic fibers by grafting a compound containing an ethylenically unsaturated double bond onto the cellulosic fibers and introducing a carboxyl group (-COOH) or its sodium salt derived from the compound into the cellulosic fibers (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-127545 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the sodium salt of the carboxyl group introduced into the cellulosic fiber has a high affinity for water, which causes the cellulosic fiber to become sticky when wet.

[0006] In order to solve the above problems, the present invention provides a method for producing metal carboxylate-grafted cellulosic fibers, in which the carboxyl groups introduced into sliver-like cellulosic fibers are prevented from converting into alkali metal salts such as Na salts, which have a high affinity for water. The present invention also provides a method for producing a moisture-absorbing and heat-generating fiber structure using the metal carboxylate-grafted cellulosic fiber of the present invention. [Means for solving the problem]

[0007] The present invention, in one aspect, comprises: a grafting step of grafting a carboxyl group-containing compound having an ethylenically unsaturated double bond onto a sliver-like cellulosic fiber to introduce a carboxyl group; and a blocking step of contacting the grafted cellulosic fiber with a treatment liquid containing at least one metal ion selected from Ca, Mg, and Zn to convert the carboxyl groups into metal salts thereof.

[0008] In another aspect, the present invention comprises: a step of preparing a metal carboxylate-grafted cellulose fiber by the method of producing a metal carboxylate-grafted cellulose fiber of the present invention; preparing a fiber structure comprising the metal carboxylate-grafted cellulosic fiber; a moisture-absorbing and heat-generating processing step of subjecting the fiber structure to a moisture-absorbing and heat-generating processing; The present invention relates to a method for producing a moisture-absorbing and heat-generating fiber structure comprising the above-mentioned compound. [Effects of the Invention]

[0009] In the method for producing a metal carboxylate-grafted cellulosic fiber of the present invention, a carboxyl group-containing compound having an ethylenically unsaturated double bond is grafted onto a sliver of cellulosic fiber to introduce a carboxyl group, and then the fiber is brought into contact with a treatment liquid containing at least one metal ion selected from Ca, Mg, and Zn, thereby converting the carboxyl group into its metal salt. Therefore, during the manufacturing process of the moisture-absorbing and heat-generating fiber structure containing the metal carboxylate-grafted cellulose fiber of the present invention, the carboxyl groups can be prevented from converting into alkali metal salts such as sodium salts, which have a high affinity for water, thereby reducing the problem of stickiness due to contact with moisture.

[0010] Furthermore, in the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention, since the metal carboxylate-grafted cellulosic fiber of the present invention is included, the stickiness problem is reduced, and processability can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a flow diagram showing the flow of steps in a method for producing a metal carboxylate-grafted cellulosic fiber according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flow diagram showing the process flow of a method for producing a moisture-absorbing and heat-generating fiber structure (fabric) according to one embodiment of the present invention. [Figure 3] FIG. 3 is a flow diagram showing the flow of steps in a method for producing a moisture-absorbing and heat-generating fiber structure (spun yarn) according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Production of cellulose-based fibers grafted with metal carboxylates] In one embodiment of the method for producing a metal carboxylate-grafted cellulosic fiber of the present invention, as shown in Figure 1, a sliver of cellulosic fiber is prepared, and a carboxyl group-containing compound containing an ethylenically unsaturated double bond is grafted onto the cellulosic fiber to introduce carboxyl groups derived from the carboxyl group-containing compound (grafting step). Next, the cellulosic fiber to which the carboxyl group-containing compound has been grafted and into which carboxyl groups have been introduced is contacted with a treatment solution containing at least one metal ion selected from Ca, Mg, and Zn to convert some or all of the introduced carboxyl groups into their metal salts (blocking step).

[0013] <Grafting process> In one embodiment of the method for producing a metal carboxylate-grafted cellulosic fiber of the present invention, a carboxyl group-containing compound containing an ethylenically unsaturated double bond (hereinafter sometimes abbreviated as "carboxyl group-containing compound") is grafted onto a cellulosic fiber such as cotton in the form of a sliver (fiber bundle), thereby introducing a carboxyl group derived from the carboxyl group-containing compound.

[0014] Examples of carboxyl group-containing compounds include compounds containing one ethylenically unsaturated double bond and one or two carboxyl groups. Specific examples of the carboxyl group-containing compound include at least one carboxylic acid selected from acrylic acid, methacrylic acid, itaconic acid, maleic acid, and fumaric acid. Grafting these compounds onto the surface of cellulosic fibers such as cotton can impart wash-resistant moisture-absorbing and heat-generating properties during the production of moisture-absorbing and heat-generating fiber structures.

[0015] Grafting of a carboxyl group-containing compound onto a cellulosic fiber can be carried out by a conventional method. The graft bond is formed through various reactions, such as a reaction in which a sliver of cellulosic fiber is irradiated with an electron beam to generate radicals on the surface of the cellulosic fiber, and a reaction in which the generated radicals are brought into contact with a carboxyl group-containing compound to graft carboxylic acid groups as graft chains onto the surface of the cellulosic fiber, as compound groups derived from the carboxyl group-containing compound. This introduces carboxyl groups into the cellulosic fiber.

[0016] The amount of the carboxyl group-containing compound added is preferably 1 to 30% by mass, more preferably 5 to 20% by mass, relative to the cellulosic fiber. The mass proportion of carboxylic acid groups, which are graft chains, in the cellulosic fiber into which carboxyl groups have been introduced is preferably 1 to 30% by mass, more preferably 5 to 30% by mass. When the amount added is within the above range, even when blended with untreated fibers such as ungrafted untreated cotton, excellent moisture-absorbing and heat-generating properties can be exhibited after the moisture-absorbing and heat-generating processing step in the method for producing a moisture-absorbing and heat-generating fiber structure described below.

[0017] Next, an example of a treatment for graft bonding will be described using cotton (natural cellulose fiber) as an example of the cellulosic fiber. In the case of a continuous method, cotton sliver for spinning is irradiated with an electron beam in a nitrogen atmosphere to generate radicals on the surface of the cotton fiber, and immediately thereafter, the cotton fiber is continuously contacted with a carboxyl group-containing compound containing an ethylenically unsaturated double bond. The reason for contacting the carboxyl group-containing compound with the surface of the cotton fiber immediately after electron beam irradiation is to prevent the radicals generated by electron beam irradiation from decaying. Because radicals are deactivated over time, it is preferable to contact the carboxyl group-containing compound with the surface of the cotton fiber immediately after electron beam irradiation.

[0018] Furthermore, it is preferable to continuously contact the carboxyl group-containing compound with the surface of the cotton fiber after electron beam irradiation, since this allows the carboxyl group-containing compound to efficiently contact the radicals generated on the surface of the cotton fiber. Furthermore, continuously contacting the carboxyl group-containing compound with the surface of the cotton fiber is advantageous for graft bonding to a long spinning sliver. Furthermore, it is preferable to irradiate with an electron beam under a nitrogen atmosphere, since the generated radicals are less likely to be deactivated. Note that with regard to the electron beam irradiation method, a so-called simultaneous irradiation method is also possible, in which the carboxyl group-containing compound is irradiated simultaneously with the contact with the surface of the cotton fiber.

[0019] In the case of continuous processing, the shape of the cellulosic fibers to be irradiated with the electron beam is preferably a continuous sheet such as a sliver or wrap, but in the case of batch processing, it is not limited to such a continuous shape.

[0020] The method for contacting the carboxyl group-containing compound with the surface of cellulosic fibers such as cotton may be any method such as immersion or spraying. For example, a method in which an aqueous solution of the carboxyl group-containing compound is prepared and a sliver is immersed in the aqueous solution, or a method in which the aqueous solution is sprayed onto the sliver is preferred.

[0021] As described above, after the carboxyl group-containing compound is grafted onto the sliver-like cellulosic fiber in the grafting step, the resulting fiber is preferably washed with water and then dried to obtain the cellulosic fiber into which the carboxyl group has been introduced.

[0022] <Blocking process> The grafted cellulose-based fibers having the carboxyl groups introduced therein are contacted with a treatment solution containing at least one metal ion selected from Ca, Mg, and Zn. Preferably, the treatment solution contains at least one metal ion selected from Ca and Zn. This treatment converts the carboxyl groups introduced into the cellulose-based fibers into their metal salts. The metal of the metal salt is at least one selected from Ca, Mg, and Zn, preferably at least one selected from Ca and Zn. This prevents the carboxyl groups from becoming alkali metal salts such as sodium salts.

[0023] Ca carboxylates, Mg carboxylates, and Zn carboxylates, especially Ca carboxylates and Zn carboxylates, which are obtained by replacing the hydrogen atoms of one or more carboxyl groups contained in carboxylic acid groups (graft chains) on cellulosic fibers with at least one metal selected from Ca, Mg, and Zn, are more stable than sodium carboxylates, do not become sticky even when in contact with moisture, and are less likely to undergo chemical changes during various treatments and processes, such as scouring, bleaching, and dyeing, that are carried out in the manufacturing process of moisture-absorbing and heat-generating fiber structures.

[0024] The treatment solution is preferably an aqueous solution obtained by dissolving a compound of at least one metal selected from Ca, Mg, and Zn in water. The concentration of the metal compound in the aqueous solution is preferably 0.01 to 50 g / L, more preferably 0.1 to 20 g / L, even more preferably 0.5 to 20 g / L, and even more preferably 5 to 20 g / L. Examples of the metal compound that serves as a source of at least one metal ion selected from Ca, Mg, and Zn include metal compounds such as calcium chloride, calcium acetate, magnesium chloride, magnesium acetate, zinc chloride, and zinc acetate, and more preferably calcium chloride, calcium acetate, and zinc acetate. Therefore, the treatment solution is preferably an aqueous calcium chloride solution, a calcium acetate solution, a magnesium chloride solution, a magnesium acetate solution, a zinc chloride solution, a zinc acetate solution, or a combination thereof. More preferably, the treatment solution is an aqueous calcium chloride solution, a calcium acetate solution, a zinc acetate solution, or a combination thereof, and even more preferably, an aqueous calcium chloride solution, a calcium acetate solution, or a combination thereof.

[0025] The treatment solution containing at least one metal ion selected from Ca, Mg, and Zn is preferably substantially free of alkali metal ions, from the viewpoint of preventing stickiness. If alkali metal ions such as Na are contained and these ions form alkali metal salts such as sodium carboxylates, stickiness tends to occur upon contact with moisture during the production process of moisture-absorbing, heat-generating fiber structures such as yarns and fabrics. Therefore, it is not preferable to use water containing a relatively large amount of alkali metal ions such as Na as water for preparing the treatment solution or treatment solution (aqueous solution).

[0026] Here, the phrase "substantially free of alkali metals" means that the treatment solution is allowed to unavoidably contain a small amount of alkali metal ions such as Na from the viewpoint of productivity, etc. The concentration of the alkali metal ions unavoidably contained is preferably 200 mg / L or less, more preferably 100 mg / L or less, even more preferably 40 mg / L or less, and even more preferably 10 mg / L or less. There is no particular lower limit for the concentration of the alkali metal ions unavoidably contained, but it is usually 1 mg / L or more.

[0027] As described above, in the blocking step, the grafted cellulosic fibers are brought into contact with the treatment liquid to convert the carboxyl groups introduced into the cellulosic fibers into their metal salts, and then the fibers are preferably washed with water and then dried to obtain metal carboxylate-grafted cellulosic fibers.

[0028] [Manufacturing of moisture-absorbing and heat-generating fiber structures] The method for producing a moisture-absorbing and heat-generating fiber structure of the present invention includes a step of producing a fiber structure containing a metal carboxylate-grafted cellulose fiber (hereinafter also referred to as a "treated fiber") produced by the method for producing a metal carboxylate-grafted cellulose fiber of the present invention. The fiber structure is specifically a yarn or a fabric such as a knitted or woven fabric. The following description will be given taking the case where the fiber structure is a fabric as an example.

[0029] (Manufacturing moisture-absorbing and heat-generating fabrics) In one embodiment, the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention is a method for producing a moisture-absorbing and heat-generating fabric. In one embodiment, the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention includes the steps of producing a sliver of treated fiber by the method for producing a metal carboxylate-grafted cellulosic fiber of the present invention, a spinning step of converting the sliver containing the treated fiber into a treated-fiber-containing spun yarn, a step of producing a fabric using at least the treated-fiber-containing spun yarn, and a moisture-absorbing and heat-generating processing step of subjecting the fabric to a moisture-absorbing and heat-generating processing, as shown in Figure 2.

[0030] In one embodiment, the method for producing the moisture-absorbing and heat-generating fiber structure of the present invention may include a step of preparing a yarn of untreated fiber, and fabric may be produced using both the spun yarn containing treated fiber and the yarn of untreated fiber.

[0031] In one embodiment of the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention, the fiber structure (fabric) is subjected to one treatment selected from scouring, bleaching, and dyeing. When these treatments are performed, they are preferably performed before the moisture-absorbing and heat-generating processing step.

[0032] In one embodiment, the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention includes a step of blending the treated fiber with other untreated fibers and spinning the blend to produce a spun yarn (blended yarn) containing the treated fiber. Blending of treated and untreated fibers is preferably carried out in a drawing process, which typically includes a doubling step. However, blending can also be carried out in a carding process, roving process, or spinning process. For example, blending can be carried out by aligning multiple webs, slivers, fleeces, or roving yarns and stretching them to a predetermined ratio in the roving and spinning processes. Blending can be achieved by migration of the constituent fibers during twisting in the roving and spinning processes. The treated fiber (spinning sliver) can also be blended with other untreated fibers (slivers) in a desired blending ratio in a beating process.

[0033] In one embodiment of the method for producing the moisture-absorbing and heat-generating fiber structure of the present invention, the treated fiber, for example, treated cotton, and the untreated fiber, for example, untreated cotton, are blended together, and then the blended spun yarn is produced in a conventional manner.

[0034] In one embodiment of the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention, after fabric is produced according to a conventional method, the fabric is subjected to a moisture-absorbing and heat-generating processing step, preferably at the final stage of the moisture-absorbing and heat-generating fabric manufacturing process. The moisture-absorbing and heat-generating processing step imparts moisture-absorbing and heat-generating properties to the treated fiber. Here, the final stage refers to a stage after any of the treatments selected from scouring, bleaching, and dyeing, if any of these treatments is performed, or a stage before the finishing treatment, if any finishing treatment is performed with an aqueous solution containing a water-absorbing softener.

[0035] In the moisture-absorbing heat-generating processing step, the fabric is preferably treated with an acid at a pH of 5 or less, then washed with water, then treated with an alkali at a pH of 7.5 or more, then washed with water, and then dried. This allows the fabric to stably exhibit its moisture-absorbing heat-generating function.

[0036] The acid treatment is preferably a treatment in which the fiber structure (fabric) is immersed in an aqueous solution obtained by adding citric acid, malic acid, or the like to water. Citric acid is added so that the concentration of the aqueous solution becomes about 1 to 10 g / L, preferably about 2 to 8 g / L. If the pH of the aqueous solution exceeds 5, it is preferable to add citric acid until the pH becomes 5 or less. The acid treatment conditions are preferably an aqueous solution temperature of 30 to 50°C and an immersion time of 10 to 30 minutes. After the acid treatment, the fiber structure is preferably washed with water at room temperature (25°C) for about 5 minutes. The acid treatment can remove Ca, Mg, Zn, and the like.

[0037] The alkali treatment involves immersing a fiber structure (fabric) in an aqueous solution prepared by adding a chelating agent (sequestering agent) and sodium bicarbonate (sodium bicarbonate, NaHCO3) to water. The chelating agent (sequestering agent) is preferably added to the aqueous solution at a concentration of approximately 1.0 g / L, particularly approximately 0.3 to 1.5 g / L, and sodium bicarbonate (sodium bicarbonate) is preferably added to the aqueous solution at a concentration of approximately 4 g / L. Soda ash (Na2CO3) can also be used instead of sodium bicarbonate (sodium bicarbonate, NaHCO3). If the pH of the aqueous solution is less than 7.5, sodium bicarbonate is preferably added until the pH reaches 7.5 or higher. The alkali treatment is preferably performed under conditions where the aqueous solution temperature is 30 to 50°C and the immersion time is 10 to 30 minutes. After the alkali treatment, the fiber structure is preferably washed with water twice, at room temperature (25°C), for approximately 5 minutes each time.

[0038] Examples of chelating agents (sequestering agents) that can be used include ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), hydroxyethylethylenediaminetriacetic acid (HEDTA), tetrasodium L-glutamate diacetate, glycol ether diaminetetraacetic acid, ethylenediamine, bipyridine, phenanthroline, porphyrin, and crown ether.

[0039] As described above, by performing an alkali treatment after an acid treatment, it is possible to remove Ca, Mg, and Zn from the carboxyl groups that have been converted into metal salts with at least one metal selected from Ca, Mg, and Zn in the blocking step, and to allow the carboxyl group (—COOH) or its sodium salt (—COONa) to exist in the graft chain, thereby maintaining the moisture-absorbing heat-generating properties.

[0040] In the method for producing a moisture-absorbing heat-generating fiber structure of the present invention, if at least one of scouring, bleaching, and dyeing is performed, it is preferable to perform this treatment before the acid treatment. Among the treatments and processes performed during the production of moisture-absorbing heat-generating fiber structures, at least one of scouring, bleaching, and dyeing, in particular, may cause chemical changes in carboxyl groups. Therefore, there has been a risk that the moisture-absorbing heat-generating properties imparted to cellulosic fibers may be deteriorated by these subsequent treatments. Completing these treatments before the moisture-absorbing heat-generating processing step eliminates the risk of deterioration of the carboxyl group (-COOH) or its sodium salt (-COONa) introduced during the moisture-absorbing heat-generating processing step, thereby providing a moisture-absorbing heat-generating fiber structure with excellent moisture-absorbing heat-generating properties.

[0041] The moisture-absorbing and heat-generating fiber structure (fabric) contains cellulose fibers that have been subjected to moisture-absorbing and heat-generating processing and other fibers, and the content of the moisture-absorbing and heat-generating processed cellulose fibers is preferably 5 to 40% by mass when the fiber structure (fabric) is taken as 100% by mass. This allows the fiber structure (fabric) to have sufficient moisture-absorbing and heat-generating function, reduces the proportion of cellulosic fibers that are damaged during grafting with electron beams, and allows the fabric to maintain its overall strength.

[0042] The other fibers are preferably at least one fiber selected from the group consisting of cellulosic fibers that have not been subjected to moisture-absorbing and heat-generating treatment, polyester fibers, nylon fibers, acrylic fibers, and polyurethane elastic fibers. When elastic yarns made of polyurethane elastic fibers are used in the production of fabrics, the resulting fabrics are suitable for innerwear such as shirts and pants.

[0043] As mentioned above, it is preferable to carry out the scouring, bleaching, and dyeing processes before the moisture-absorbing and heat-generating processing step. The scouring, bleaching, and dyeing processes can each be carried out using conventional methods. Cellulosic fibers turn white through scouring and bleaching. In particular, cotton, if not scouring and bleaching, will have reduced water absorption, a dull color, and its product value will decrease regardless of whether it is dyed or not. The scouring and bleaching processes can be carried out, for example, by immersing the fiber structure (fabric) in an aqueous solution obtained by adding hydrogen peroxide (H2O2) and sodium hydroxide (NaOH) to water.

[0044] The dyeing treatment is preferably carried out as needed after the scouring treatment and bleaching treatment. If the textile structure (fabric) is white, it may not be dyed or may be treated with a fluorescent whitening agent. If the textile structure (fabric) is colored, the type of dye may be selected depending on the type of untreated fiber. If the textile structure (fabric) is made of the treated fiber (metal carboxylate-grafted cellulose fiber) and untreated cellulose fiber, it is preferable to dye it with a reactive dye. If the textile structure (fabric) is made of the treated fiber (metal carboxylate-grafted cellulose fiber) and polyurethane fiber, it is preferable to dye it with at least one dye selected from reactive dyes and disperse dyes (they may be used in combination). After dyeing, the textile is neutralized, soaped, and washed with water according to conventional methods.

[0045] In one embodiment of the method for producing a moisture-absorbing heat-generating fiber structure of the present invention, it is preferable to perform a finishing process using an aqueous solution containing a water-absorbent softener after the moisture-absorbing heat-generating processing step. The use of a water-absorbent softener can impart softness without reducing the moisture-absorbing heat-generating properties. The use of a water-repellent softener is undesirable because it reduces the water absorption and moisture-absorbing heat-generating properties.

[0046] In a moisture-absorbing and heat-generating fiber structure (fabric) containing a moisture-absorbing and heat-generating cellulosic fiber and other fibers, the moisture-absorbing and heat-generating cellulosic fiber preferably accounts for 5 to 40% by mass when the total mass of the moisture-absorbing and heat-generating fiber structure (fabric) is taken as 100% by mass. This range allows the fiber structure (fabric) to exhibit high moisture-absorbing and heat-generating properties. For the same reason, the mass proportion of the treated fiber in the fiber structure (fabric) subjected to the moisture-absorbing and heat-generating processing step is preferably 5 to 40% by mass when the total mass of the fabric is taken as 100% by mass.

[0047] When the fiber structure (fabric) is a knitted fabric suitable for innerwear, for example, three yarns are used as supply yarns, one of which is a blended spun yarn containing 30% by mass of the treated fiber (metal carboxylate-grafted cellulose fiber) and 70% by mass of conventional untreated cellulose fiber, and the remaining two are untreated cellulose spun yarns. If the total mass of the fiber structure (fabric) is taken as 100% by mass, a fiber structure (fabric) containing 10% by mass of the treated fiber is obtained. By subjecting this fiber structure (fabric) to the moisture-absorbing and heat-generating treatment described above, a moisture-absorbing and heat-generating fiber structure (fabric) containing 10% by mass of moisture-absorbing and heat-generating cellulose fiber is obtained. It is preferable that the supply yarns for producing knitted fabrics suitable for innerwear further include an elastic yarn made of an elastic fiber such as polyurethane fiber.

[0048] The fabric is preferably a knitted or woven fabric. Knitted fabrics and woven fabrics are suitable for use as innerwear. Knitted fabrics are particularly stretchy and flexible, making them suitable for use as innerwear. It is preferable that one or two out of every three yarns constituting the fabric be the blended spun yarn, and the remaining yarn be a cotton spun yarn that has not been subjected to moisture-absorbing and heat-generating processing. Knitted fabrics include circular knitting, weft knitting, warp knitting (including tricot knitting and raschel knitting), and pile knitting, and may be any of plain knitting, jersey knitting, rib knitting, smooth knitting (double knitting), rib knitting, purl knitting, Denbigh knitting, cord knitting, atlas knitting, chain knitting, insertion knitting, and knitting combinations thereof. Various interlacing methods are used to produce knitted fabrics. Interlacing knitted fabrics may be warp knitting or weft knitting, and examples include tricot, raschel knitting, and circular knitting. Furthermore, the knitting structure may be any of half knitting, reverse half knitting, double atlas knitting, double Denbigh knitting, and knitting combinations thereof. Examples of woven fabrics include plain weave, twill weave, satin weave, varied plain weave, varied twill weave, varied satin weave, variegated weave, patterned weave, single-ply weave, double weave, multi-ply weave, warp pile weave, weft pile weave, leno weave, and combinations thereof. Among these, weft knitted fabrics including circular knitting, or warp knitted fabrics are preferred.

[0049] The mass per unit area of ​​the fabric is 80 to 300 g / m 2 is preferable, and more preferably 90 to 250 g / m 2 and more preferably 100 to 200 g / m 2 If the mass per unit area of ​​the fabric is within the above range, it is suitable for use as innerwear.

[0050] (Production of moisture-absorbing heat-generating cellulose-based spun yarn) In one embodiment, the method for producing a moisture-absorbing, heat-generating fiber structure of the present invention is a method for producing a moisture-absorbing, heat-generating cellulosic spun yarn. As shown in Figure 3, the method for producing a moisture-absorbing, heat-generating fiber structure of the present invention includes a step of producing treated fiber by the method for producing a metal carboxylate-grafted cellulosic fiber of the present invention, a spinning step of converting a sliver containing the treated fiber into a treated-fiber-containing spun yarn, and a moisture-absorbing, heat-generating processing step of subjecting the treated-fiber-containing spun yarn to a moisture-absorbing, heat-generating processing.

[0051] In one embodiment of the method for producing a moisture-absorbing and heat-generating fiber structure of the present invention, the treated fiber-containing spun yarn may be a spun yarn containing 100% by mass of the treated fiber (metal carboxylate-grafted cellulose fiber), or may be a blended spun yarn of the treated fiber (metal carboxylate-grafted cellulose fiber) and untreated fiber. Preferred untreated fibers are the same as those described above in (Production of moisture-absorbing and heat-generating fabric).

[0052] In one embodiment of the method for producing a moisture-absorbing heat-generating fiber structure of the present invention, the fiber structure (spun yarn) is subjected to one treatment selected from scouring, bleaching, and dyeing. When these treatments are performed, they are preferably performed before the moisture-absorbing heat-generating processing step. Each of these treatments can be performed by a conventional method. If these treatments are completed before the moisture-absorbing heat-generating processing step, a moisture-absorbing heat-generating fiber structure (dyed yarn) with good moisture-absorbing heat-generating properties can be provided.

[0053] The moisture-absorbing and heat-generating processing step in the method for producing moisture-absorbing and heat-generating cellulose spun yarn of the present invention is the same as the method described above (production of moisture-absorbing and heat-generating fabric) except that the target of the moisture-absorbing and heat-generating processing is yarn. [Example]

[0054] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples. <Hygroscopic heat generation> (1) A sample of fabric (knitted fabric) is taken to a size of 20 cm x 20 cm, dried in a dryer for 4 hours, and left overnight in a desiccator containing silica gel. (2) After drying, the sample fabric is folded in half, a thermocouple temperature sensor is attached to the center, and the fabric is folded in half again to form a test specimen. (3) After treating the test specimen in a thermo-hygrostat at 20°C and 40% RH for 2 hours, the thermo-hygrostat settings are changed to 20°C and 90% RH, and the temperature change is measured every minute for 15 minutes. (4) A knitted fabric made from 50-count cotton yarn using untreated cotton sliver (Comparative Example 1 below) is used as the reference fabric, and the difference between the maximum temperature of the reference fabric over the 15-minute measurement period and the maximum temperature of the fabric of Example 1 is calculated as the maximum temperature difference (°C).

[0055] Example 1 <Sliver processing> Cotton sliver (mass per unit length, unit grain: 25.0 g / 6 yd (4.6 g / m)) was irradiated with an electron beam at a dose of 40 kGy and an acceleration voltage of 200 kV under a nitrogen atmosphere using an electrocurtain-type electron beam irradiation device EC250 / 30 / 90L (manufactured by Iwasaki Electric Co., Ltd.). The irradiated sliver was immediately immersed in a 16% by weight aqueous solution of acrylic acid (manufactured by Nacalai Tesque, Inc.) containing 0.5% by weight of a penetrant and squeezed with a mangle to achieve a pickup rate of approximately 100% by weight of the sliver. The amount of acrylic acid added was such that the mass ratio of acrylic acid groups (graft chains) in the carboxyl-introduced cotton sliver was 8% by weight. The sliver was then washed with water to remove unreacted acrylic acid, and then impregnated with a calcium chloride aqueous solution (CaCl2 10 g / L). This converted the carboxyl groups of the grafted acrylic acid into calcium salts. The cotton was then washed again with water, dried at 80°C, and coiled and stored in a container to obtain calcium acrylate-grafted cotton. The sliver thus obtained is called "treated cotton."

[0056] <Spun yarn production> (1) Blended yarn containing treated cotton The treated cotton and untreated cotton were blended in a blending process to spin a yarn having a cotton count of 50. The proportion of treated cotton in the blended yarn was set to 30% by mass. (2) Untreated cotton yarn Untreated cotton was used to spin a yarn with a yarn count of 50.

[0057] <Knitted fabric manufacturing> The treated cotton blended yarn, untreated cotton spun yarn, and elastic yarn were prepared. The blended yarn containing the treated cotton was fed in a ratio of two untreated cotton spun yarns to one treated cotton blended yarn, and the elastic yarn was inserted so that it accounted for 7% by mass of the fabric. The elastic yarn was a commercially available polyurethane elastic yarn, 22decitex. The elastic yarn was inserted as a plated yarn to each yarn while tension was applied so that it was stretched 2.5 times its original length. A plain knit fabric was knitted using a circular knitting machine. The knit fabric was then heat-treated at 200°C for 90 seconds.

[0058] <Scouring, bleaching, dyeing> The resulting knitted fabric was subjected to a conventional scouring treatment, a bleaching treatment, and a dyeing treatment using a reactive dye.

[0059] <Hygroscopic heat-generating processing process (calcium release process)> After the dyeing process, the following (1) acid treatment and (2) alkali treatment were carried out as moisture-absorbing and heat-generating processing steps. (1) Acid treatment An aqueous solution of 2 g / L citric acid (pH 5 or less) was prepared. The knitted fabric was immersed in this aqueous solution at a bath ratio of 1:15 and subjected to acid treatment at 40°C for 20 minutes. Thereafter, the fabric was washed with water at room temperature (25°C) for 5 minutes. (2) Alkali treatment Next, an aqueous solution containing 4 g / L of sodium bicarbonate (NaHCO3) and 1 g / L of a chelating agent (diethylenetriaminepentaacetic acid (DTPA)) was prepared to have a pH of 7.5 or higher. The knitted fabric was immersed in this aqueous solution at a bath ratio of 1:15 and subjected to an alkali treatment at 40°C for 20 minutes. The fabric was then washed twice with water at room temperature (25°C) for 5 minutes each. Thereafter, the washed knitted fabric was dried to obtain the moisture-absorbing and heat-generating fabric of Example 1.

[0060] In the moisture-absorbing and heat-generating fabric of Example 1, when the total mass of the moisture-absorbing and heat-generating fabric was taken as 100 mass%, the content of the moisture-absorbing and heat-generating processed cotton was 9 mass%, and the total content of untreated cotton was 84 mass%. In addition, the mass of the fabric was 170 g / m 2 It was. The blended yarn containing the treated cotton used in the production of the moisture-absorbing and heat-generating fabric of Example 1 has been subjected to the moisture-absorbing and heat-generating processing step (calcium release step) to become a moisture-absorbing and heat-generating cellulose-based spun yarn. If the moisture-absorbing and heat-generating cellulose-based spun yarn is taken as 100% by mass, the content of moisture-absorbing and heat-generating processed cellulose fiber contained therein is 30% by mass.

[0061] (Comparative Example 1) A fabric of Comparative Example 1 was obtained in the same manner as in Example 1, except that untreated cotton spun yarn was used instead of the blended yarn containing treated cotton.

[0062] The maximum temperature of each of the obtained moisture-absorbing and heat-generating fabric of Example 1 and the fabric of Comparative Example 1 (reference fabric) was measured according to the above <Moisture-absorbing and heat-generating properties>, and the moisture-absorbing and heat-generating properties of the moisture-absorbing and heat-generating fabric of Example 1 were evaluated.The maximum temperature difference (°C) was 0.6°C.

[0063] By performing moisture-absorbing and heat-generating processing after the dyeing process, the moisture-absorbing and heat-generating properties were stabilized, and the maximum temperature difference (℃), which is an evaluation index of moisture-absorbing and heat-generating properties, was 0.6℃, resulting in a cellulosic fiber fabric with good moisture-absorbing and heat-generating properties.

[0064] By converting the carboxyl groups of acrylic acid grafted onto the surface of cellulose fibers in the sliver state into calcium salts, the carboxyl groups are prevented from becoming alkali metal salts such as sodium salts. This means that the moisture-absorbing and heat-generating fabric does not become sticky even when it comes into contact with moisture during the manufacturing process, and it has good processability.

[0065] An inner shirt was sewn using the moisture-absorbing and heat-generating fabric of Example 1, and a wear test was conducted. It was confirmed that the shirt was warm, comfortable to wear, and gentle on the skin. [Industrial Applicability]

[0066] The moisture-absorbing heat-generating fabrics and moisture-absorbing heat-generating spun cellulosic yarns containing the metal carboxylate-grafted cellulosic fibers produced by the method for producing the metal carboxylate-grafted cellulosic fibers of the present invention are suitable for innerwear such as shirts, pants, socks, etc. They are also suitable for T-shirts, etc.

Claims

1. a grafting step of grafting a carboxyl group-containing compound having an ethylenically unsaturated double bond onto a sliver-like cellulosic fiber to introduce a carboxyl group; a blocking step of contacting the grafted cellulosic fibers with a treatment liquid containing at least one metal ion selected from Ca, Mg, and Zn to convert the carboxyl groups into metal salts thereof.

2. 2. The method for producing metal carboxylate-grafted cellulosic fibers according to claim 1, wherein the treatment liquid is substantially free of alkali metal ions.

3. 3. The method for producing a metal carboxylate-grafted cellulose fiber according to claim 1, wherein the treatment liquid is a calcium chloride aqueous solution, a calcium acetate aqueous solution, a magnesium chloride aqueous solution, a magnesium acetate aqueous solution, a zinc chloride aqueous solution, a zinc acetate aqueous solution, or a combination thereof.

4. A process for preparing a metal carboxylate-grafted cellulose fiber by the method for producing a metal carboxylate-grafted cellulose fiber according to any one of claims 1 to 3; preparing a fiber structure comprising the metal carboxylate-grafted cellulosic fiber; a moisture-absorbing and heat-generating processing step of subjecting the fiber structure to a moisture-absorbing and heat-generating processing; A method for producing a moisture-absorbing and heat-generating fiber structure, comprising:

5. Before the moisture absorption and heat generation processing step, The method for producing a moisture-absorbing and heat-generating fiber structure according to claim 4, wherein the fiber structure is subjected to a refining and bleaching treatment, and optionally a dyeing treatment.

6. 6. The method for producing a moisture-absorbing heat-generating fiber structure according to claim 4 or 5, wherein in the moisture-absorbing heat-generating processing step, the fiber structure is subjected to an acid treatment at a pH of 5 or less, followed by rinsing with water, then an alkali treatment at a pH of 7.5 or more, followed by rinsing with water, and then a drying treatment.

7. 7. The method for producing a moisture-absorbing and heat-generating fiber structure according to claim 6, wherein the acid treatment is a treatment of immersing the fiber structure in an aqueous solution containing citric acid, and the alkali treatment is a treatment of immersing the fiber structure in an aqueous solution containing a chelating agent and sodium bicarbonate (baking soda).

8. 8. The method for producing a moisture-absorbing and heat-generating fiber structure according to claim 7, wherein in both the acid treatment and the alkali treatment, the temperature of the aqueous solution is 30 to 50° C. and the immersion time is 10 to 30 minutes.

9. The method for producing a moisture-absorbing, heat-generating fiber structure according to any one of claims 4 to 8, wherein the moisture-absorbing, heat-generating fiber structure comprises graft-treated cellulose fibers that have been subjected to moisture-absorbing, heat-generating processing and other fibers, and when the total mass of the moisture-absorbing, heat-generating fiber structure is taken as 100 mass%, the content of the moisture-absorbing, heat-generating processed cellulose fibers is 5 to 40 mass%.

10. 10. The method for producing a moisture-absorbing and heat-generating fiber structure according to claim 9, wherein the other fibers are at least one type of fiber selected from cellulosic fibers, polyester fibers, nylon fibers, acrylic fibers, and polyurethane elastic fibers that have not been subjected to moisture-absorbing and heat-generating processing.

11. The method for producing a moisture-absorbing and heat-generating fiber structure according to any one of claims 4 to 10, wherein the fiber structure is a yarn, a knitted fabric, or a woven fabric.

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