Thermal insulation fiber structure, and cold weather gear and disaster preparedness blanket containing said fiber structure

Abstract

To provide a heat-retaining fiber structure that enables a high heat retention to last and provide a cold protection product or a blanket for disaster stockpiling that utilize the fiber structure, so as to solve the problems of, for example, insufficient heat retention and a lack of focus on the lasting of the heat retention, by offering improvements for problems with conventional fiber products such as clothes and bedding that have been proposed to have a heat retention by attempts including using fibers that absorb moisture and generate heat in knitted fabric, forming a metal layer on one side of nonwoven fabric, and reflecting infrared rays constantly emitted from the surface of the human body to create a heat retention effect.SOLUTION: A heat-retaining fiber structure is obtained by laminating a knitted, woven or nonwoven fabric containing a fiber having a high moisture absorption rate and a moisture-absorbing, heat-generation lasting fiber, and a knitted, woven or nonwoven fabric at least part of which is coated with a metal.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermally insulating fiber structure and to a cold weather product and a disaster preparedness blanket containing the fiber structure. [Background technology]

[0002] Conventionally, attempts have been made to impart more effective heat retention to textile products such as clothing and bedding. For example, Patent Document 1 reports a knitted or woven fabric using a fiber that generates heat when it absorbs moisture, a so-called moisture-absorbing and heat-generating fiber.

[0003] Furthermore, the nonwoven fabric reported in Patent Document 2 has a metal layer formed on one side of the nonwoven fabric, which reflects infrared rays that are constantly emitted from the surface of the human body, thereby creating a heat-retaining effect.

[0004] Furthermore, Patent Document 3 reports cold weather clothing that aims to achieve even greater heat retention by combining a moisture-absorbing and heat-generating fiber with a metal layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-31796 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-241292 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-192547 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the heat retention properties obtained in Patent Documents 1 and 2 are not sufficient, and Patent Document 3 does not consider the sustainability of heat generation, so there is room for improvement. An object of the present invention is to provide a heat-retaining fiber structure that can maintain high heat retention properties, and cold weather gear and disaster preparedness blankets that utilize said fiber structure. [Means for solving the problem]

[0007] As a result of intensive research conducted by the inventors to achieve the above-mentioned objectives, they have succeeded in achieving immediate and sustained moisture absorption and heat generation by combining a fiber with a high moisture absorption rate with a fiber with sustained moisture absorption and heat generation properties, and in providing an even greater heat retention effect by layering a metal-coated fiber structure on a fiber structure containing these two types of moisture absorption and heat generation fibers.

[0008] That is, the present invention is achieved by the following means. (1) Contains fibers with high moisture absorption rate and moisture-absorbing and heat-generating fibers Moisture-absorbing and heat-generating layer and a heat-retaining fiber structure obtained by laminating a knitted fabric, a woven fabric, or a nonwoven fabric at least partly coated with a metal. The heat-retaining fiber structure is characterized in that the moisture-absorbing and heat-generating layer is formed as a single layer of knitted fabric, woven fabric, or nonwoven fabric, or is formed by laminating these. . (2) A heat-retaining fiber structure according to (1), characterized in that the fiber having a high moisture absorption rate includes an acrylate fiber and / or a cellulose fiber. (3) A heat-retaining fiber structure according to (2), characterized in that the cellulosic fiber contains flame-retardant rayon. (4) The heat-retaining fiber structure according to any one of (1) to (3), wherein the moisture-absorbing, heat-generating, and sustained fiber contains an acrylate fiber having an Mg and / or Ca salt type carboxyl group. (5) A heat-retaining fiber structure according to any one of (1) to (4), characterized in that the metal used for the coating contains aluminum. (6) The heat-retaining fiber structure according to any one of (1) to (5), characterized in that the thickness is 6 mm or less. (7) Weight is 500g / m 2 The heat-retaining fiber structure according to any one of (1) to (6), characterized in that: (8) A cold weather item or a blanket for disaster preparedness, containing the heat-retaining fiber structure according to any one of (1) to (7). [Effects of the Invention]

[0009] The thermal insulation fiber structure of the present invention provides an excellent thermal insulation effect immediately and continuously. The thermal insulation fiber structure of the present invention, which has such properties, can be used, for example, in clothing or bedding to produce cold weather gear with effective thermal insulation. Furthermore, blankets using the thermal insulation fiber structure are thin and lightweight yet exhibit sufficient thermal insulation properties, making them suitable for use as simple blankets (disaster prevention blankets) that are stockpiled in large quantities during normal times and used in evacuation shelters during disasters. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a graph showing the measurement results of moisture absorption and heat generation properties of fiber structures of each example and comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. The fiber having a high moisture absorption rate (hereinafter also referred to as "fiber A") of the present invention is a fiber that absorbs a large amount of moisture at the initial stage of moisture absorption and therefore generates a large amount of heat at the initial stage of moisture absorption. Specifically, it is a moisture-absorbing and heat-generating fiber that has a temperature of 22.0°C or higher, preferably 22.5°C or higher, 5 minutes after the start of moisture absorption, as measured by the measurement method described below. When the temperature is 22.0°C or higher, the heat-retaining effect of the present invention can be obtained immediately. Examples of such fiber A include cellulosic fibers (e.g., cotton, rayon, etc.), synthetic fibers (e.g., acrylate fibers, etc.), and animal fibers (e.g., wool, etc.). Among these, acrylate fibers having a crosslinked structure and a carboxyl group are preferred because of their high saturated moisture absorption, and acrylate fibers having a sodium or potassium salt-type carboxyl group are particularly preferred because of their high moisture absorption rate. Furthermore, flame-retardant rayon, a cellulosic fiber, can be suitably used when the heat-retaining fiber structure of the present invention is used in applications requiring fire resistance. These fibers may be used in combination as fiber A, if necessary.

[0012] An example of such an acrylate fiber is a crosslinked acrylonitrile fiber disclosed in Japanese Patent Laid-Open No. 2000-314082, which is a moisture-absorbing and desiccant fiber in which an increase in nitrogen content introduced by crosslinking an acrylonitrile fiber having an acrylonitrile content of 85 to 95% by weight with a hydrazine compound is 1.0 to 5.0% by weight, in which a portion of the remaining nitrile groups are converted into alkali metal salt-type carboxy groups of 3.0 to 6.0 mmol / g by hydrolysis, and in which the difference in moisture absorption rate between the conditions of 20°C × 50% RH and 20°C × 95% RH is 50 to 150% by weight.

[0013] In addition, commercially available acrylate fibers having a crosslinked structure and a carboxyl group may be used, such as Ex (registered trademark), Dismel (registered trademark), Moisfine (registered trademark), and Moiscare (registered trademark) manufactured by Toyobo Co., Ltd., and Sunburner (registered trademark) manufactured by Teijin Frontier Co., Ltd.

[0014] The moisture-absorbing and heat-generating fiber of the present invention (hereinafter also referred to as "fiber B") is a fiber that continues to absorb moisture and generate heat for a long period of time, and has a temperature drop rate of 40% or less, preferably 30% or less, more preferably 10% or less, and even more preferably 5% or less at 60 minutes after the start of moisture absorption compared to the temperature at 5 minutes, as measured by the measurement method described below. Therefore, the heat-retaining fiber structure of the present invention, which uses fiber A and fiber B in combination, can achieve excellent heat retention by achieving both immediate heat generation and sustained heat generation.

[0015] Examples of such fiber B include Mg salt-type or Ca salt-type acrylate fibers in which the counter ion of the carboxyl group is a magnesium ion or a calcium ion. Among these, Mg salt-type acrylate fibers have high flame retardancy and are therefore suitable for use in applications where fire resistance is required for the heat-retaining fiber structure of the present invention.

[0016] Examples of such Mg salt-type or Ca salt-type acrylate fibers include those in which the counter ions of the carboxyl groups of the above-mentioned known or commercially available acrylate fibers have been converted to magnesium ions or calcium ions. Examples of the conversion method include a method in which the known or commercially available acrylate fibers are immersed in an aqueous solution of magnesium or calcium sulfate or nitrate to perform ion exchange. Furthermore, in the case of a manufacturing method such as that described in JP 2000-314082 A, a method in which an alkaline magnesium compound or calcium compound is used in the hydrolysis treatment can also be employed.

[0017] The amount of salt-type carboxyl groups contained in such Mg salt-type or Ca salt-type acrylate fibers may be any amount that can realize the above-mentioned temperature reduction rate, and is preferably 2.0 to 10.0 mmol / g, more preferably 2.5 to 8.0 mmol / g, and even more preferably 3.0 to 7.0 mmol / g.

[0018] The knitted, woven or nonwoven fabric containing the fiber having a high moisture absorption rate and the moisture-absorbing and heat-generating sustaining fiber of the present invention (hereinafter also referred to as "moisture-absorbing and heat-generating layer") preferably contains 30 to 70 wt %, more preferably 35 to 65 wt %, of the fiber A and preferably 10 to 50 wt %, more preferably 15 to 45 wt %, of the fiber B, from the viewpoint of obtaining excellent heat retention that combines the above-mentioned rapid heat generation and sustained heat generation. In addition to these two types of fiber, the moisture-absorbing and heat-generating layer may also contain other types of fiber, such as acrylic fiber, polyester fiber or polyamide fiber, depending on the purpose.

[0019] The moisture-absorbing and heat-generating layer can be manufactured by conventional methods such as knitting, weaving, needle punching, spun lace, stitch bonding, thermal bonding, and other nonwoven fabric manufacturing methods using yarns obtained by blending, spinning and twisting, core yarn, uniformly mixed composite spinning, twisting, blending, etc.

[0020] The yarn may be a blend of fiber A and fiber B, or a yarn containing fiber A and a yarn containing fiber B may be separately produced. In the latter case, a single knitted or woven fabric may be produced by interlacing or interweaving, or separate knitted or woven fabrics may be produced from the respective yarns and then laminated. In the nonwoven fabric production method described above, fiber A and fiber B may both be blended together and then made into a nonwoven fabric, or a nonwoven fabric containing fiber A and a nonwoven fabric containing fiber B may be laminated together to form a single nonwoven fabric.

[0021] The basis weight of the moisture absorbing and heat generating layer is not particularly limited, but from the viewpoint of achieving sufficient heat retention for practical use while reducing weight, the lower limit is preferably 30 g / m 2 More preferably, 50 g / m 2 The upper limit is preferably 400 g / m 2 Less than 300 g / m 2 The following is the result.

[0022] The knitted fabric, woven fabric, or nonwoven fabric (hereinafter also referred to as "infrared reflective layer") of the present invention, at least partially coated with a metal, has the function of reflecting heat emitted from the above-mentioned moisture-absorbing and heat-generating layer or the human body, thereby suppressing heat dissipation to the outside and improving heat retention. Examples of such infrared reflective layers include those formed by forming a metal layer on at least a portion of one side of a knitted fabric, woven fabric, or nonwoven fabric by a method such as vapor deposition or sputtering, using a metal that reflects infrared rays, such as aluminum, stainless steel, titanium, gold, silver, copper, tin, platinum, chromium, nickel, or an alloy thereof. Among these, aluminum or an alloy of aluminum and another metal is preferred from the standpoint of cost, and vacuum vapor deposition, ion beam vapor deposition, or the like is preferred as the coating method from the standpoint of production efficiency.

[0023] The thickness of the metal film to be formed is preferably 10 nm or more, more preferably 30 nm or more, and preferably 500 nm or less, more preferably 200 nm or less, as a lower limit. If the thickness is too thin, the heat retention effect due to infrared reflection and blocking, and durability in actual use may be insufficient. Furthermore, if the thickness is too thick, the texture and breathability of the substrate may deteriorate, and phenomena such as discoloration of the metal may easily occur.

[0024] The knitted, woven, or nonwoven fabric to be coated with the metal is not particularly limited and can be selected depending on the required performance, such as breathability, texture, and stretchability. Woven fabrics, knitted fabrics such as circular knitting and warp knitting, and nonwoven fabrics obtained by the above-mentioned conventional nonwoven fabric manufacturing methods can be used. The weave of the knitted or woven fabric is also not particularly limited, but a smooth, non-irregular surface is preferred from the viewpoint of the durability of the metal film. Examples of smooth weaves include plain weave and smooth weave for knitted fabrics, and plain weave, rip weave, and satin weave for woven fabrics.

[0025] The fibers constituting the knitted, woven, or nonwoven fabrics are not particularly limited, but include polyester fibers such as polyethylene terephthalate, polytrimethylene terephthalate, and polybutylene terephthalate; polyamide fibers such as nylon 6 and nylon 66; acrylic fibers; polyolefin fibers such as polypropylene and polyethylene; polyurethane fibers; and synthetic fibers such as polyimide fibers. These fibers may be used alone or in combination. Among these, polyester fibers, polyamide fibers, acrylic fibers, polyolefin fibers, and polyurethane fibers are particularly preferred due to their low hygroscopicity. On the other hand, natural fibers, recycled fibers, and semi-synthetic fibers can make the vacuum required during the physical vapor deposition process difficult due to their inherent hygroscopicity, resulting in failure of vapor deposition or insufficient adhesion of the metal thin film. However, blending is possible to the extent that it does not significantly impede vacuumization. For example, when using cotton as the natural fiber, a blend of polyester staple fibers and cotton may be interwoven or interknitted into a woven or knitted fabric. Alternatively, 100% cotton spun yarn may be used and arranged as part of the warp and weft yarns of the fabric.

[0026] The basis weight of the knitted fabric, woven fabric or nonwoven fabric is not particularly limited, but the lower limit is preferably 15 g / m 2 More preferably, 20 g / m 2 The upper limit is preferably 300 g / m 2 or less, more preferably 250 g / m 2 By setting the basis weight within this range, the fabric can be suitably used for applications that come into contact with the skin, such as general clothing and bedding.

[0027] The method for producing the knitted fabric, knitted fabric, or nonwoven fabric is not particularly limited, and can be any of the conventionally known methods described above, and it is preferred that the knitted fabric or nonwoven fabric is thoroughly dried after undergoing general steps such as scouring, bleaching, dyeing, drying, and heat setting, etc. Drying the knitted fabric or nonwoven fabric prevents the evacuation required for the physical vapor deposition step from being hindered.

[0028] Furthermore, Metal Gear (registered trademark) manufactured by Toyobo Co., Ltd. is commercially available as a nonwoven fabric having metallic aluminum vapor-deposited on one side, and can be suitably used as the infrared reflective layer of the present invention.

[0029] The heat-retaining fiber structure of the present invention is characterized by comprising the above-mentioned moisture-absorbing and heat-generating layer and infrared-reflective layer laminated together, and the contents of the moisture-absorbing and heat-generating layer and the infrared-reflective layer in the heat-retaining fiber structure are preferably 60 to 90% by weight and 10 to 40% by weight, respectively, and more preferably 65 to 85% by weight and 15 to 35% by weight.

[0030] In addition, the heat-retaining fiber structure of the present invention may have a two-layer structure in which one moisture-absorbing heat-generating layer and one infrared-reflecting layer are laminated, or may have a three-layer structure in which infrared-reflecting layers are laminated on both sides of a moisture-absorbing heat-generating layer, a three-layer structure in which moisture-absorbing heat-generating layers are laminated on both sides of an infrared-reflecting layer, or a structure in which an additional layer is added to the above two layers, as long as the object of the present invention is not impaired.

[0031] There are no particular restrictions on the thickness of the heat-retaining fiber structure of the present invention, as long as it is within a range that does not impair the texture or functionality, but when the fiber structure is used in products where storability (lightness, ease of folding, etc.) is important, such as disaster preparedness blankets that are stored in large quantities, the thickness is preferably 6 mm or less, more preferably 5 mm or less, and even more preferably 4 mm or less.

[0032] The basis weight of the heat-retaining fiber structure of the present invention is not particularly limited as long as it does not impair the function or texture, as with the thickness. However, when considering the ease of handling and storage, the basis weight of the fiber structure is preferably 500 g / m 2 or less, more preferably 450 g / m 2 or less, more preferably 400 g / m 2 The following is the result.

[0033] The heat-retaining fiber structure of the present invention may be subjected to a surface resin treatment to prevent deterioration of the texture and appearance due to fuzzing. In this case, it is desirable to use a flame-retardant resin to prevent a decrease in the flame retardancy of the heat-retaining fiber structure.

[0034] There are no particular limitations on the method for manufacturing the heat-retaining fiber structure of the present invention, and any method can be used in which the layers, including the moisture-absorbing and heat-generating layer and the infrared-reflective layer, are laminated together using conventional methods such as bonding with a heat-sealing resin, sewing, or needle punching.

[0035] The thermal insulation fiber structure of the present invention can be used in clothing and bedding to produce cold weather gear with effective thermal insulation. Furthermore, when acrylate-based fibers are used in the moisture-absorbing and heat-generating layer, not only thermal insulation but also various functions inherent to acrylate-based fibers, such as deodorizing and antibacterial properties, can be added, thereby suppressing unpleasant sweat odors and the growth of bacteria. Furthermore, blankets using the thermal insulation fiber structure can exhibit sufficient thermal insulation even when they are thin and lightweight. Therefore, the thermal insulation fiber structure of the present invention can be suitably used as a simple blanket (disaster prevention blanket) to be used in evacuation shelters during disasters, and is effective in improving the hygienic environment of evacuation shelters and providing protection against the cold. [Example]

[0036] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The measurement methods used for evaluation in the examples are as follows.

[0037] (1) Amount of salt-type carboxyl groups Approximately 1 g of thoroughly dried sample was weighed (X [g]), 200 ml of water was added, and then 1 mol / l hydrochloric acid solution was added while heating to 50°C to adjust the pH to 2. Next, a titration curve was obtained using a 0.1 mol / l sodium hydroxide solution according to the usual method. From the titration curve, the amount of sodium hydroxide solution consumed by the carboxyl groups (Y [ml]) was determined, and the amount of carboxyl groups was calculated using the following formula. Carboxylic acid amount [mmol / g] = 0.1Y / X Separately, the amount of H-type carboxyl groups was determined by similarly obtaining a titration curve without adjusting the pH to 2 by adding 1 mol / L hydrochloric acid during the above-mentioned carboxyl group amount measurement procedure. From these results, the amount of salt-type carboxyl groups was calculated using the following formula. Amount of salt-type carboxyl groups [mmol / g] = (amount of carboxyl groups) - (amount of H-type carboxyl groups)

[0038] (2) Moisture absorption and heat generation A sample (a carded web in the case of raw cotton) was dried in a 105°C hot air dryer for 16 hours or more, and then 7.0 g of the sample was weighed out and left in a thermo-hygrostat at 20°C and 40% RH for 24 hours or more. The sample was then placed in a moisture absorption heat generation measuring sensor inside the thermo-hygrostat at 20°C and 90% RH, and the moisture absorption heat generation temperature was measured over time using a moisture absorption heat generation measuring instrument. The sample temperatures (T0 [°C], T5 [°C], and T60 [°C], respectively) at 0, 5, and 60 minutes after the start of moisture absorption were calculated. The temperature drop rate was calculated from the results of these measurements using the following formula: Temperature reduction rate [%]={(T5-T60) / (T5-T0)}×100 Note that "RH" above means relative humidity, and "40% RH" indicates that the relative humidity is 40%.

[0039] Example 1 (1) Preparation of Mg salt-type acrylate fibers A spinning dope was prepared by dissolving an acrylonitrile-based polymer (90% acrylonitrile and 10% methyl acrylate) in a 48% aqueous solution of sodium rhodanate. This was spun, washed, drawn, crimped, and heat-treated according to conventional methods to obtain a 0.9 (dtex) x 70 (mm) raw fiber. 5 kg of 30 wt% hydrazine hydrate was added to 1 kg of this raw fiber, and crosslinked at 98°C for 3 hours. After washing the crosslinked fiber, 9 kg of a 3 wt% aqueous sodium hydroxide solution was added, and the fiber was hydrolyzed at 92°C for 5 hours. The carboxyl groups were then converted to the H-type by treatment with a 1 mol / L aqueous nitric acid solution. After washing, the pH was adjusted to 12 with a 1 mol / L aqueous sodium hydroxide solution, and the fiber was washed to obtain a sodium salt-type acrylate fiber. After that, 8 kg of 10% magnesium nitrate aqueous solution was added, and the fiber was converted to the Mg salt type at 60°C for 2 hours. After thorough rinsing with water, the fiber was dehydrated and dried to obtain the desired Mg salt type acrylate fiber. The amount of Mg salt type carboxyl groups in this acrylate fiber was 5.2 mmol / g. Furthermore, the temperature drop rate after moisture absorption and heat generation measurement was -5.3%.

[0040] (2) Fabrication of heat-retaining fiber structures DFG (registered trademark)-1.7T51, a flame-retardant rayon manufactured by Daiwabo Rayon Co., Ltd. (the temperature 5 minutes after the start of moisture absorption in the moisture absorption heat generation measurement described above was 23.1°C), the Mg salt type acrylate fiber obtained by the above method, and K8-1.7T51, an acrylic fiber manufactured by Nippon Exlan Kogyo Co., Ltd., were uniformly mixed in a weight ratio of 50:30:20 to form a moisture absorption heat generation layer with a basis weight of 110 g / m. 2 Next, a nonwoven fabric having metal aluminum vapor-deposited thereon, METALGEAR (registered trademark, manufactured by Toyobo Co., Ltd., weight 30 g / m), was applied as an infrared reflective layer to the card web. 2 ) were laminated with the vapor-deposited surface facing inward, and then needle-punched to integrate them, yielding a nonwoven fabric. Then, vinyl chloride emulsion (Viniblan (registered trademark) 278) manufactured by Nissin Chemical Industry Co., Ltd. was applied as a flame-retardant resin at a rate of approximately 10 g / m2 on both sides of the obtained nonwoven fabric. 2 The fiber structure of Example 1 (thickness: 3 mm, basis weight: 149 g / m) was coated so as to obtain 2 The results of the flame retardancy test of the fiber structure using the 45° methenamine method showed a maximum char length of 3.9 cm and an average char length of 3.7 cm, which met the flame retardancy performance standard (for blankets) established by the Flame Retardant Product Certification Committee established by the Japan Fire Retardant Association.

[0041] Comparative Example 1 In Example 1, the moisture-absorbing and heat-generating layer was made of the Mg salt-type acrylate fiber described in Example 1 and TORCON (registered trademark), a polyphenylene sulfide fiber manufactured by Toray Industries, Inc., in a weight ratio of 30:70. The same processing as in Example 1 was carried out to obtain the fiber structure of Comparative Example 1 (thickness 3 mm, basis weight 136 g / m). 2 ) was obtained.

[0042] Comparative Example 2 Commercially available flame-retardant polyester blanket (thickness 6 mm, basis weight 517 g / m 2 ) was used as Comparative Example 2.

[0043] Comparative Example 3 A commercially available acrylic blanket was used as Comparative Example 3.

[0044] The hygroscopic heat generation properties of the fiber structures obtained in Example 1 and Comparative Examples 1 to 3 were measured by the method described above, and the measurement results are shown in the graph of FIG.

[0045] The graph in Figure 1 shows that the fiber structure of Example 1 had a high initial heat generation rate and was resistant to temperature drops. These results indicate that the fiber structure of Example 1 was excellent in both immediate heat generation and sustained heat generation. In contrast, the fiber structure of Comparative Example 1 did not contain Fiber A and therefore was inferior in immediate heat generation. Furthermore, the fiber structures of Comparative Examples 2 and 3, which are conventional examples, did not have a moisture-absorbing and heat-generating layer or an infrared-reflective layer and were therefore inferior in both immediate heat generation and sustained heat generation.

Claims

1. A heat-retaining fiber structure comprising a moisture-absorbing and heat-generating layer containing a fiber with a high moisture absorption rate and a fiber with long-lasting moisture absorption and heat generation, and a knitted fabric, woven fabric or nonwoven fabric, at least a portion of which is coated with metal, wherein the moisture-absorbing and heat-generating layer is either a single layer of knitted fabric, woven fabric or nonwoven fabric, or a laminate of these.

2. 2. The heat-retaining fiber structure according to claim 1, wherein the fiber having a high moisture absorption rate includes an acrylate-based fiber and / or a cellulosic fiber.

3. 3. The heat-retaining fiber structure according to claim 2, wherein the cellulosic fiber comprises flame-retardant rayon.

4. 4. The heat-retaining fiber structure according to claim 1, wherein the moisture-absorbing, heat-generating, and sustaining fiber contains an acrylate fiber having a Mg and / or Ca salt type carboxyl group.

5. 5. The heat-retaining fiber structure according to claim 1, wherein the metal used for the coating includes aluminum.

6. 6. The heat-retaining fiber structure according to claim 1, wherein the thickness is 6 mm or less.

7. Weight per unit area: 500g / m ２ The heat-retaining fiber structure according to any one of claims 1 to 6, characterized in that:

8. A cold weather item or a blanket for disaster preparedness, comprising the heat-retaining fiber structure according to any one of claims 1 to 7.

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