Infrared Radiation-Emitting Resin Composition

Abstract

Disclosed is an infrared radiation-emitting resin composition including an infrared radiation-emitting material and a resin, in which the infrared radiation-emitting material includes a titanium dioxide, a calcined hydrotalcite-like compound, and a nano-sized diamond, and in the infrared radiation-emitting material, the mass ratio between the titanium dioxide and the calcined hydrotalcite-like compound is 60:40 to 90:10, while the content of the nano-sized diamond is 0.01 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of the sum of the titanium dioxide and the calcined hydrotalcite-like compound.

Description

1. Field of the Invention

[0001] The present invention relates to an infrared radiation-emitting resin composition.More particularly, the present invention relates to an infrared radiation-emitting resincomposition that is utilized for imparting functionality such as drying of various materialsand heat retention in clothing materials, for heating and cooling, and for hairdressing, andthe like.2. Description of the Related Art

[0002] As infrared radiation-emitting materials, ceramics including alumina, titania,zirconia, silica, and the like have been hitherto suggested. Such materials emit far-infraredradiation, and as far-infrared radiation is absorbed by a substance, the substance is heated.

[0003] Water molecules exhibit vibration such as stretching and bending, and when watermolecules absorb far-infrared radiation, the water molecules are excited and then broughtinto a highly vibrational state. As a result, the temperature of the water molecules isincreased. Therefore, when substances including water molecules, human bodies, animals,plants, and the like absorb far-infrared radiation, temperature is increased.

[0004] Therefore, in order to efficiently warm up substances including water molecules,human bodies, animals, plants, and the like, it is necessary to use an infrared radiationemitting material that emits far-infrared radiation having a wavelength capable of excitingthe vibration of water molecules. As such an infrared radiation-emitting material, theinventors of the present invention have proposed, in Japanese Patent No. 2137667, aninfrared radiation-emitting material capable of emitting far-infrared radiation that is easilyabsorbed by animals and plants, such as human bodies.SUMMARY OF THE INVENTION

[0006] When an infrared radiation-emitting material is applied to, for example, a fiberthat is used for a garment, the infrared radiation-emitting material absorbs far-infraredradiation emitted from the human body wearing the garment to accumulate heat, and it isnecessary to emit the accumulated thermal energy to the human body as far-infraredradiation. That is, an infrared radiation-emitting material is required to absorb far-infraredradiation emitting from another substance to thereby accumulate heat, and to emit theaccumulated thermal energy efficiently as far-infrared radiation.

[0007] However, the infrared radiation-emitting material described in Japanese Patent No.2137667 has a problem that, for example, the efficiency of absorbing far-infraredradiation emitting from a human body and the like and accumulating heat is not sufficient.As a result, there is a problem that when the accumulated thermal energy is emitted asfar-infrared radiation, the emission efficiency in a wavelength range (for example, 4 to 20μm) that is easily absorbed by animals and plants, such as a human body, is not uniform,and absorption and emission of far-infrared radiation by animals and plants, such as ahuman body, occur insufficiently.

[0008] The present invention was achieved in view of such circumstances, and it is anobject of the invention to provide an infrared radiation-emitting resin compositionincluding an infrared radiation-emitting material having a high average value ofemissivity in a predetermined wavelength range.

[0009] Thus, embodiments of the present invention are as follows.

[0010] [1] An infrared radiation-emitting resin composition including an infraredradiation-emitting material and a resin,wherein the infrared radiation-emitting material includes a titanium dioxide, acalcined hydrotalcite-like compound, and a nano-sized diamond,in the infrared radiation-emitting material, a mass ratio between the titaniumdioxide and the calcined hydrotalcite-like compound is 60:40 to 90:10, and a content ofthe nano-sized diamond is 0.01 parts by mass or more and 0.5 parts by mass or less withrespect to 100 parts by mass of a total amount of the titanium dioxide and the calcinedhydrotalcite-like compound.

[0011] [2] The infrared radiation-emitting resin composition according to [1], in whichthe infrared radiation-emitting resin composition has a plate shape, a tubular shape, asheet shape, or a fibrous shape, in all of which the infrared radiation-emitting material isdispersed in the resin.

[0012] [3] The infrared radiation-emitting resin composition according to [1] or [2], inwhich an average particle size of the titanium dioxide is 10 nm or more and 1000 nm orless.

[0013] [4] The infrared radiation-emitting resin composition according to any one of [1]to [3], in which an average particle size of the calcined hydrotalcite-like compound is 10nm or more and 1000 nm or less.

[0014] [5] The infrared radiation-emitting resin composition according to any one of [1]to [4], in which an average particle size of secondary particles of the nano-sized diamondis 5 nm or more and 200 nm or less.

[0015] According to the present invention, an infrared radiation-emitting resincomposition including an infrared radiation-emitting material having a high average valueof emissivity in a predetermined wavelength range can be provided.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a graph showing a far-infrared radiation emissivity at a wavelength of 5to 20 μm for a blank sample.FIG. 2 is graphs showing the far-infrared radiation emissivity at a wavelength of5 to 20 μm for samples of Examples 1A-1 to 1A-3.FIG. 3 is graphs showing the far-infrared radiation emissivity at a wavelength of5 to 20 μm for samples of Examples 1A-4 to 1A-6.FIG. 4 is graphs showing the far-infrared radiation emissivity at a wavelength of5 to 20 μm for samples of Comparative Examples 1B-1 to 1B-3.FIG. 5 is graphs showing the far-infrared radiation emissivity at a wavelength of5 to 20 μm for samples of Comparative Examples 1B-4 to 1B-6.FIG. 6 is graphs showing the far-infrared radiation emissivity at a wavelength of5 to 20 μm for samples of Comparative Examples 1B-7 and 1B-8.FIG. 7 is a graph showing the body surface temperatures of the thigh beforewearing leggings of Example AMF-1, Comparative Example BMF-1, and Blank L-1 and20 minutes after wearing the leggings.FIG. 8 is a graph showing the temperature changes in nonwoven fabric sheetsfrom the initiation of heating to the time point of 140 seconds after heating of thenonwoven fabric sheets of Example NWA-1, Comparative Example NWB-1, and BlankBL-1.FIG. 9 is a graph showing changes in the water content of wood in a dryingexperiment of using a drying apparatus provided with a nonwoven fabric board ofExample NHA-1 and a drying apparatus that was not provided with the nonwoven fabricboard of Example NHA-1.DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, the present invention will be described in detail in the following orderbased on specific embodiments.1. Infrared radiation-emitting resin composition1.1. Infrared radiation-emitting material1.2. Titanium dioxide1.3. Calcined hydrotalcite-like compound1.4. Nano-sized diamond2. Method for producing infrared radiation-emitting resin composition

[0018] (1. Infrared radiation-emitting resin composition)The infrared radiation-emitting resin composition according to the presentembodiment has an infrared radiation-emitting material and a resin. It is preferable thatthe infrared radiation-emitting material is in a powder form, and it is preferable that aninfrared radiation-emitting material powder is dispersed in the resin in the infraredradiation-emitting resin composition. The infrared radiation-emitting material will bedescribed below.

[0019] As the resin, known resins can be used according to the use applications of theinfrared radiation-emitting resin composition. Examples of the known resins includethermoplastic resins such as a polyester, a polyethylene, a polypropylene, a polystyrene,a polycarbonate, a polyurethane, an acrylic resin, a nylon, and a polylactic acid-basedresin; thermosetting resins such as an epoxy resin, a melamine resin and a urea resin;rubbers such as a natural rubber and a synthetic rubber; and regenerated resins such as arayon. In the present embodiment, polyolefin series such as polypropylene andpolyethylene; polyester series such as polyethylene terephthalate; nylon; and the like aresuitably used.

[0020] The infrared radiation-emitting resin composition is used after being molded intovarious shapes according to the use applications. In the present embodiment, the infraredradiation-emitting resin composition preferably has a plate shape, a tubular shape, a sheetshape, or a fibrous shape, and more preferably a fibrous shape. In a fibrous-shapedinfrared radiation-emitting resin composition, an infrared radiation-emitting material isdispersed in a fibrous-shaped resin.

[0021] A fibrous-shaped infrared radiation-emitting resin composition is fiberized by aspinning process. Such a fiber is a chemical fiber artificially produced by using a chemicaltechnique. Chemical fibers include fibers other than natural fibers, and examples includesynthetic fibers (polyester-based and polyamide-based fibers), semisynthetic fibers(cellulose-based fibers), and regenerated fibers (cellulose-based fibers).

[0022] The mixing ratio of the infrared radiation-emitting material and the resin may beset according to the use application. In the present embodiment, when the infraredradiation-emitting resin composition has a plate shape, a tubular shape, or a sheet shape,it is preferable that the amount of the infrared radiation-emitting material is 10 parts bymass or more and 20 parts by mass or less with respect to 100 parts by mass of the resin.Furthermore, when the infrared radiation-emitting resin composition has a fibrous shape,it is preferable that the amount of the infrared radiation-emitting material is 0.5 parts bymass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the resin.

[0023] (1.1. Infrared radiation-emitting material)The infrared radiation-emitting material is a material that emits far-infraredradiation. In the present embodiment, it is particularly preferable that the infraredradiation-emitting material is a material that emits far-infrared radiation having awavelength suitable for exciting water molecules included in substances, human bodies,animals, plants, and the like. Furthermore, it is preferable that this infrared radiationemitting material is a material having a high far-infrared radiation emissivity at awavelength in the range of from 5 μm to 20 μm, and particularly preferably in the rangeof from 7 μm to 14 μm. The far-infrared radiation emissivity can be measured by using aFourier Transform Infrared Spectroscopy (FTIR) based on, for example, a measurementmethod approved by the Japan Far Infrared Rays Association.

[0024] In the present embodiment, the infrared radiation-emitting material includes atitanium dioxide, a calcined hydrotalcite-like compound, and a nano-sized diamond.Furthermore, in the infrared radiation-emitting material, the mass ratio between thetitanium dioxide and the calcined hydrotalcite-like compound is 60:40 to 90:10, and thecontent of the nano-sized diamond is 0.01 parts by mass or more and 0.5 parts by mass orless with respect to 100 parts by mass of the sum of the titanium dioxide and the calcinedhydrotalcite-like compound.

[0025] When the mass ratio between the titanium dioxide and the calcined hydrotalcitelike compound is in the above-described range, the far-infrared radiation emissionefficiency of the infrared radiation-emitting material according to the present embodimentcan be increased.

[0026] It is preferable that the mass ratio between the titanium dioxide and the calcinedhydrotalcite-like compound is 70:30 to 80:20.

[0027] Furthermore, since the nano-sized diamond has a very high thermal conductivity,the absorption and emission efficiency for infrared radiation-emitting thermal energy ofthe infrared radiation-emitting material can be increased when the infrared radiationemitting material includes the nano-sized diamond. Therefore, by adjusting the contentof the nano-sized diamond to be in the above-described range, the far-infrared radiationemission efficiency of the infrared radiation-emitting material according to the presentembodiment can be increased, and the emission efficiency at a wavelength in the rangeof from 5 μm to 20 μm can be made uniform. However, from the viewpoint of cost, theupper limit of the content of the nano-sized diamond is set to the above-described value.

[0028] It is preferable that the content of the nano-sized diamond is 0.02 parts by massor more and 0.2 parts by mass or less with respect to 100 parts by mass of the sum of thetitanium dioxide and the calcined hydrotalcite-like compound.

[0029] (1.2. Titanium dioxide)Titanium dioxide exists in the forms of anatase type (tetragonal), rutile type(tetragonal), and brookite type (orthorhombic) according to the difference in the crystalstructure. In the present embodiment, the crystal structure of titanium dioxide is notparticularly limited; however, from the viewpoint of availability as an industrial rawmaterial, the crystal structure is preferably anatase type or rutile type. Furthermore, as amethod for industrially producing titanium dioxide, a chlorine method and a sulfuric acidmethod are known; however, in the present embodiment, the method for producingtitanium dioxide is not particularly limited.

[0030] In the present embodiment, it is preferable that the titanium dioxide is in a powderform. The average particle size D50 of the titanium dioxide powder is preferably 10 nmor more and 1000 nm or less, and more preferably 100 nm or more and 700 nm or less.In the present embodiment, the average particle size D50 is a value measured by a laserdiffraction method.

[0031] Examples of commercially available products of the above-described titaniumdioxide include "CR-60" (rutile type) manufactured by ISHIHARA SANGYO KAISHA,LTD., "A-100" (anatase type) manufactured by ISHIHARA SANGYO KAISHA, LTD.,"TAF-520" (anatase type) manufactured by Fuji Titanium Industry Co., Ltd., "TA301"(anatase type) manufactured by Fuji Titanium Industry Co., Ltd., "JR-800" (rutile type)manufactured by TAYCA CORPORATION, "JA-1" (anatase type) manufactured byTAYCA CORPORATION, "SA-1" (anatase type) manufactured by SAKAI CHEMICALINDUSTRY CO., LTD., and "R-11.P" (rutile type) manufactured by SAKAI CHEMICALINDUSTRY CO., LTD.

[0032] (1.3. Calcined hydrotalcite-like compound)A hydrotalcite-like compound is a layered inorganic compound represented bychemical formula: Mg1-xAlx(OH)2(CO3)x / 2⋅mH2O. As is obvious from the chemicalformula, a hydrotalcite-like compound includes water of crystallization, and the water ofcrystallization is present between layers. When a hydrotalcite-like compound is heated,elimination of the water of crystallization occurs at around 180°C to 230°C.

[0033] On the other hand, the infrared radiation-emitting resin composition according tothe present embodiment is obtained by blending an infrared radiation-emitting materialwith a resin; however, each treatment (kneading, crosslinking, or the like) at the time ofblending may be carried out after heating to a temperature of 200°C or higher. At thistime, when the infrared radiation-emitting resin composition includes a hydrotalcite-likecompound, the water of crystallization included in the hydrotalcite-like compound maybe removed and then contaminated the infrared radiation-emitting resin composition, anddefects such as molding failure and foaming in the infrared radiation-emitting resincomposition may occur.

[0034] Thus, in the present embodiment, in order to suppress the above-described defects,a calcined hydrotalcite-like compound obtainable by removing the water of crystallizationincluded in a hydrotalcite-like compound is used. Specifically, with regard to a calcinedhydrotalcite-like compound, "m" in the above-described chemical formula is preferablyin the range of 0 ≤ m ≤ 0.05 as a result of removal of the water of crystallization.

[0035] In order to set the range of "m" to be 0 ≤ m ≤ 0.05, for example, the hydrotalcitelike compound may be dried under predetermined drying conditions. The dryingconditions are not particularly limited; however, for example, the drying temperature ispreferably 120°C to 350°C, more preferably 130°C to 340°C, and even more preferably140°C to 330°C. Furthermore, the drying time is preferably 1 to 24 hours, more preferably1.5 to 22 hours, and even more preferably 2 to 20 hours.

[0036] In the present embodiment, it is preferable that the calcined hydrotalcite-likecompound is in a powder form. The average particle size D50 of the calcined hydrotalcitelike compound powder is preferably 10 nm or more and 1000 nm or less, and morepreferably 100 nm or more and 700 nm or less. In the present embodiment, the averageparticle size D50 is a value measured by a laser diffraction method.Incidentally, it is preferable that the average particle size of the titanium dioxidepowder and the average particle size of the calcined hydrotalcite-like compound powderare similar.

[0037] Examples of commercially available products of the above-described calcinedhydrotalcite-like compound include "DHT-4C" (Mg4.3Al2(OH)12.6CO3⋅mH2O: 0 ≤ m ≤0.05) manufactured by Kyowa Chemical Industry Co., Ltd., "DHT-4A-2"(Mg4.3Al2(OH)12.6CO3⋅mH2O: 0 ≤ m ≤ 0.05) manufactured by Kyowa Chemical IndustryCo., Ltd., and "HT-9" (Mg1-xAlx(OH)x / 2CO3⋅mH2O: 0 ≤ x ≤ 0.5, 0 ≤ m ≤ 0.05)manufactured by SAKAI CHEMICAL INDUSTRY CO., LTD.

[0038] (1.4. Nano-sized diamond)Nano-sized diamond is fine particulate diamond, and the surface layer of a corehaving a diamond structure is coated with a carbon layer such as amorphous carbon,graphene, or graphite. Nano-sized diamond is excited by infrared radiation and emitsinfrared radiation having a wavelength of about 1 to 10 μm. Since the number of carriersto be excited is large as compared with oxides, even when the content of the nano-sizeddiamond is in the above-described range, the far-infrared radiation emission efficiencycan be sufficiently increased.

[0039] In the present embodiment, the nano-sized diamond is a collection of secondaryparticles composed of aggregates of diamond particles having a primary particle size ofabout 2 to 7 nm. The average particle size D50 of the secondary particles is preferably 50nm or more and 200 nm or less, and more preferably 80 nm or more and 150 nm or less.In the present embodiment, the average particle size D50 of the nano-sized diamond is avalue measured by a dynamic light scattering method using laser light.

[0040] The method for producing the nano-sized diamond is not particularly limited;however, usually, the nano-sized diamond is produced by a detonation (explosion)method. In the detonation method, detonating powder including carbon is detonated in atightly sealed state, and as the crystal structure of a portion of carbon in the detonatingpowder is changed to the diamond structure under the high temperature and high pressureobtainable at the time of detonation, fine particulate diamond is obtained.

[0041] Examples of commercially available products of the above-described nano-sizeddiamond include "SCM NANODIA" (average particle size D50: 50 to 100 nm)manufactured by Dia Materials Co., Ltd., "NanoAmando" (average particle size primaryparticles: 2.6 nm ± 0.5 nm, secondary particles: 50 nm) manufactured by NanoCarbonResearch Institute, Ltd., and "DINNOVARE" (average particle size primary particles: 4to 6 nm) manufactured by Daicel Corporation.

[0042] (2. Method for producing infrared radiation-emitting resin composition)The infrared radiation-emitting resin composition according to the presentembodiment is obtained as a mixture by mixing a resin and an infrared radiation-emittingmaterial. In the mixture, it is preferable that the infrared radiation-emitting material isdispersed in the resin.

[0043] Mixing of the resin and the infrared radiation-emitting material is carried out by,for example, melt-kneading the resin and the infrared radiation-emitting material using aknown kneading machine. Examples of the known kneading machine include a mixer, akneader, a roll, and an extruder. Furthermore, a mixture of the resin and the infraredradiation-emitting material may be obtained by producing a masterbatch including theinfrared radiation-emitting material at a high concentration and kneading the masterbatchwith the remaining resin raw material.

[0044] In the present embodiment, it is preferable that the obtained infrared radiationemitting resin composition is molded into a predetermined shape according to the useapplication. Molding of the infrared radiation-emitting resin composition may beperformed simultaneously with the above-described mixing.

[0045] When the infrared radiation-emitting resin composition is molded into a plateshape, a tubular shape, or a sheet shape, it is preferable to use molding methods such asinjection molding, extrusion molding, T-die molding, and calendar molding. Furthermore,when the infrared radiation-emitting resin composition is molded into a fibrous shape, itis preferable to use spinning methods such as melt spinning, dry spinning, wet spinning,and centrifugal spinning. The infrared radiation-emitting resin composition that has beenmolded into a fibrous shape is processed into, for example, a woven fabric, a knitted fabric,a nonwoven fabric, a felt, a punching sheet, and the like.

[0046] Thus, embodiments of the present invention have been described; however, thepresent invention is not intended to be limited to the above-described embodiments, andvarious modifications may be made within the scope of the present invention.EXAMPLES

[0047] Hereinafter, the invention will be described in more detail by using Examples;however, the present invention is not intended to be limited to these Examples.

[0048] (Test 1)As raw materials of an infrared radiation-emitting material, a titanium dioxidepowder ("TA301" manufactured by Fuji Titanium Industry Co., Ltd.), a calcinedhydrotalcite-like compound powder ("HT-9" manufactured by SAKAI CHEMICALINDUSTRY CO., LTD.), and a nano-sized diamond powder ("NanoAmando"manufactured by NanoCarbon Research Institute, Ltd.) were prepared. The averageparticle size D50 of the titanium dioxide powder was 580 nm, the average particle sizeD50 of the calcined hydrotalcite-like compound powder was 500 nm, and the averageparticle size of secondary particles of the nano-sized diamond was 50 nm.

[0049] The prepared titanium dioxide powder, calcined hydrotalcite-like compound, andnano-sized diamond were mixed in the formulation indicated in Table 1 to obtain infraredradiation-emitting materials. Incidentally, in Comparative Example 1B-8, 90 parts bymass of the titanium dioxide powder, 10 parts by mass of a silicon dioxide powder("RHEOROSIL (registered trademark) MT-10" manufactured by Tokuyama Corporation),and 5 parts by mass of a yttrium oxide ("3NUU" manufactured by Shin-Etsu Rare EarthsCo., Ltd.) were mixed to obtain an infrared radiation-emitting material.

[0050] [Table 1]

[0051] The obtained infrared radiation-emitting material and a polyethylene resin wereblended such that the ratio between the total mass of titanium dioxide and the calcinedhydrotalcite-like compound in the infrared radiation-emitting material and the mass ofthe polyethylene resin was 1:9, and the mixture was kneaded for 10 minutes at a speed ofrotation of 50 rpm and a resin temperature of 180°C by using a kneading machine("PLASTI-CORDER LAB-STATION W50EHT type" manufactured by BrabenderGmbH & Co. KG) to obtain pellets.

[0052] The obtained pellets were subjected to hot pressing by using a press moldingmachine (manufactured by Toho Press Manufacturing, Ltd.) under the conditions of aheating temperature of 200°C and a gauge pressure of 10 MPa, and a sheet-shapedinfrared radiation-emitting resin composition having a dimension of 100 mm x 100 mmx 0.6 mm was obtained.

[0053] Incidentally, in Comparative Example 1B-7, 0.005 parts by mass of nano-sizeddiamond was blended with 100 parts by mass of a polyethylene resin, and a sheet-shapedinfrared radiation-emitting resin composition was obtained in the same manner asdescribed above. Furthermore, in Comparative Example 1B-8, the components wereblended with a polyethylene resin such that the ratio between the total mass of the titaniumdioxide and the silicon dioxide, and the mass of the polyethylene resin was 1:9, and asheet-shaped infrared radiation-emitting resin composition was obtained in the samemanner as described above. In addition, as a blank, a sheet-shaped resin compositioncomposed only of a polyethylene resin, without including an infrared radiation-emittingmaterial, was obtained in the same manner as described above.

[0054] For the obtained infrared radiation-emitting resin compositions, the far-infraredspectral emissivity was measured as follows. From an obtained sheet-shaped infraredradiation-emitting resin composition, a test specimen having a dimension of 40 mm x 40mm was cut out, and the far-infrared spectral emissivity for the wavelength range of farinfrared radiation (5 to 20 μm) was measured by an FT-IR method by using a far-infraredspectral emissivity measuring machine ("SpectrumOne Frontier T" manufactured byPerkinElmer, Inc.) under the conditions of a measurement temperature of 40°C, anenvironmental temperature of 20°C, and a humidity of 65%. Furthermore, also for theblank sample, the far-infrared spectral emissivity was measured under the abovedescribed conditions. When the average emissivity of the blank in the wavelength rangeof far-infrared radiation (7 to 14 μm) was calculated from the measurement results, theaverage emissivity was 83.375%.

[0055] In the Examples, in the light of the criteria for the evaluation items "emissioncharacteristics and spectral emissivity" in the "Far Infrared Radiation Textile ProductsEvaluation Criteria" specified by the Japan Far Infrared Rays Association, a samplehaving an average emissivity of 92.0% or higher in the wavelength range of far-infraredradiation (7 to 14 μm) was considered satisfactory. The results are shown in Table 2 andFIGS. 1 to 6.

[0056] [Table 2]

[0057] From Table 2 and FIGS. 1 to 6, it could be confirmed that when the infraredradiation-emitting material includes the above-mentioned components, and the contentsthereof are within the above-mentioned ranges, an infrared radiation-emitting resincomposition having a high average emissivity is obtained.

[0058] (Test 2)As raw materials of an infrared radiation-emitting material, a titanium dioxidepowder ("CR-60" manufactured by ISHIHARA SANGYO KAISHA, LTD.), a calcinedhydrotalcite-like compound powder ("HT-9" manufactured by SAKAI CHEMICALINDUSTRY CO., LTD.), and a nano-sized diamond powder ("NanoAmando"manufactured by NanoCarbon Research Institute, Ltd.) were prepared. The averageparticle size D50 of the titanium dioxide powder was 210 nm, the average particle sizeD50 of the calcined hydrotalcite-like compound powder was 500 nm, and the averageparticle size D50 of secondary particles of the nano-sized diamond was 50 nm.

[0059] 85 parts by mass of the prepared titanium dioxide powder, 15 parts by mass of thecalcined hydrotalcite-like compound powder, and 0.02 parts by mass of the nano-sizeddiamond were mixed to obtain an infrared radiation-emitting material (Example 2A-1).The infrared radiation-emitting material of Example 2A-1 and a nylon resin were blendedsuch that the mass ratio between the infrared radiation-emitting material and the nylonresin was 1:9, and the mixture was kneaded by using a resin melting and kneadingmachine ("50C type 150" manufactured by Toyo Seiki Seisaku-sho, Ltd.) under theconditions of a heating temperature of 270°C and a speed of rotation of 100 rpm toproduce a masterbatch 2AM-1.

[0060] Next, the masterbatch 2AM-1 and a nylon resin were blended such that the massratio between the masterbatch 2AM-1 and the nylon resin was 1:9, and the mixture wasmelt-spun by using a multifilament production apparatus (manufactured by MusashinoKikai Co., Ltd.) under the conditions of a heating temperature of 280°C to produce anylon multifilament yarn AMF-1 having a degree of fineness of 88 dtex and a filamentcount of 36f.

[0061] The produced nylon multifilament yarn AMF-1 was processed by a POY-DTYmethod (method of performing partial drawing by spinning at a high speed to obtain aPartially Oriented Yarn (POY) and converting the POY into a Draw Textured Yarn (DTY)through drawing and false twisting processes) under the conditions of a false twisted POYdrawing roller winding speed of 4,000 m / min to produce a POY yarn, the POY yarn wassubjected to twisting at a rate of 3,200 t / m of draw textured yarn DTY and heat-setting,and the resultant was untwisted and processed into a bulky and elastic yarn.

[0062] The processed AMF-1 was used to produce cloth by using a circular knittingmachine, and a pair of leggings (AMF-1) was produced.

[0063] A nylon multifilament yarn BMF-1 was produced by the same method asdescribed above, except that an infrared radiation-emitting material (ComparativeExample 2B-3) obtained by mixing 50 parts by mass of a titanium dioxide powder, 50parts by mass of a calcined hydrotalcite-like compound powder, and 0.005 parts by massof nano-sized diamond was used, and a pair of leggings (BMF-1) was produced by usingthe produced nylon multifilament yarn BMF-1.

[0064] In addition, a nylon multifilament yarn L-1 was produced by the same method asdescribed above, except that a resin composition composed of a nylon resin withoutincluding an infrared radiation-emitting material was used, and a pair of leggings (L-1)was produced by using the produced nylon multifilament yarn L-1.

[0065] The heat retaining property of the leggings was evaluated by wearing the obtainedleggings and measuring the body surface temperature after taking off the leggingsaccording to a testing method described below.

[0066] A test subject entered a laboratory chamber maintained at an indoor temperatureof 20°C and an indoor humidity of 65%, subsequently the test subject maintained a sittingposition in a resting state, the body surface temperature of a measurement site (thigh) wasmeasured by using a thermography (FLIR A615 manufactured by FLIR Systems, Inc.),and the body surface temperature at a stable time point was designated as body surfacetemperature before wearing. After checking, the test subject took on the leggingsproduced as described above and maintained a sitting position in a resting state, and afterminutes, the test subject took off the leggings. The body surface temperature of thethigh immediately after taking off the leggings was measured by using a thermography("FLIR A615" manufactured by FLIR Systems, Inc.). The results are shown in Table 3and FIG. 7.

[0067] [Table 3]

[0068] From Table 3 and FIG. 7, it was confirmed that the leggings (AMF-1) exhibitedgood heat retaining property.

[0069] (Test 3)As raw materials of an infrared radiation-emitting material, a titanium dioxidepowder ("A-100" manufactured by ISHIHARA SANGYO KAISHA, LTD.), a calcinedhydrotalcite-like compound powder ("DHT-4A-2" manufactured by Kyowa ChemicalIndustry Co., Ltd.), and a nano-sized diamond powder ("SCM NANODIA" manufacturedby Dia Materials Co., Ltd.) were prepared. The average particle size D50 of the titaniumdioxide powder was 100 nm, the average particle size D50 of the calcined hydrotalcitelike compound powder was 400 nm, and the average particle size D50 of secondaryparticles of the nano-sized diamond was 50 to 100 nm.

[0070] 80 parts by mass of the prepared titanium dioxide powder, 20 parts by mass of thecalcined hydrotalcite-like compound powder, and 0.03 parts by mass of the nano-sizeddiamond were mixed to obtain an infrared radiation-emitting material (Example 3A-3).The infrared radiation-emitting material of Example 3A-3 and a polyethyleneterephthalate (PET) resin were blended such that the mass ratio between the infraredradiation-emitting material and the polyethylene terephthalate resin was 1:9, and themixture was kneaded by using a resin melting and kneading machine ("50C type 150"manufactured by Toyo Seiki Seisaku-sho, Ltd.) under the conditions of a heatingtemperature of 280°C and a speed of rotation of 100 rpm to produce a masterbatch 3MA1.

[0071] Next, the obtained masterbatch 3MA-1 and the PET resin were blended such thatthe mass ratio between the master batch 3MA-1 and the PET resin was 1:9, and themixture was melt-spun by using a staple fiber spinning and drawing production apparatusunder the conditions of a heating temperature of 280°C to produce a PET resin staple yarnPSA-1 having a degree of fineness of 6.6 dtex and a fiber length of 51 mm.

[0072] The produced staple yarn PSA-1 was used as a raw material, and a web wasformed by using a carding machine ("H2DS" manufactured by Ikegami Kikai K.K.). Theformed web was laminated in layers with a layering machine ("IK30-2" manufactured byIkegami Kikai K.K.), and the laminate was produced into a PET nonwoven fabric NWA1 having a width of 1000 mm and a cloth thickness of 100 g / m2by using a nonwovenfabric needle punching machine ("NL21" manufactured by Fehrer AG).

[0073] A PET resin staple yarn PSB-1 was produced by the same method as describedabove, except that an infrared radiation-emitting material (Comparative Example 3B-4)obtained by mixing 20 parts by mass of a titanium dioxide powder and 80 parts by massof a calcined hydrotalcite-like compound powder was used, and a PET nonwoven fabricNWB-1 was produced by using the produced staple yarn PSB-1.

[0074] In addition, a PET resin staple yarn BL-1 was produced by the same method asdescribed above, except that a resin composition composed of a PET resin withoutincluding an infrared radiation-emitting material was used, and a PET nonwoven fabricBL-1 was produced by using the produced staple yarn BL-1.

[0075] The temperature changes generated when the produced PET nonwoven fabric washeated were measured as follows.

[0076] A test specimen having a dimension of 200 mm x 150 mm was cut out from theobtained PET nonwoven fabric. The cut test specimen was heated from an upwarddiagonal direction of the test specimen by using two halogen lamps ("CHP-500"manufactured by CASTER Co., Ltd.) disposed so as to face each other, with the testspecimen interposed therebetween, and the average temperature of the test specimen(PET nonwoven fabric) during a time period starting from the initiation of heating to 140seconds was measured. The power output of the halogen lamps was 500 W. The averagetemperature of the test specimen was measured by detecting a spectrum at 7.5 to 14 μmfrom above the test specimen by using an infrared camera ("FLIR SC655" manufacturedby FLIR Systems, Inc.). The results are shown in Table 4 and FIG. 8.

[0077] [Table 4]

[0078] From Table 4 and FIG. 8, it could be confirmed that the thermal energy emittedfrom the PET nonwoven fabric NWA-1 was high.

[0079] (Test 4)The infrared radiation-emitting material of Example 3A-3 and a PET resin wereblended such that the mass ratio between the infrared radiation-emitting material and thePET resin was 1:9, and the mixture was kneaded by using a resin melting and kneadingapparatus ("50C type 150" manufactured by Toyo Seiki Seisaku-sho, Ltd.) under theconditions of a heating temperature of 280°C and a speed of rotation of 100 rpm toproduce a masterbatch 3MA-1.

[0080] Next, the obtained masterbatch 3MA-1 and the PET resin were blended such thatthe mass ratio between the masterbatch 3MA-1 and the PET resin was 1:9, and the mixturewas melt-spun by using a staple fiber spinning and drawing production apparatus underthe conditions of a heating temperature of 280°C to produce a PET resin staple yarn PSA2 having a degree of fineness of 8.8 dtex and a fiber length of 51 mm.

[0081] The produced staple yarn PSA-2 was used as a raw material, and a web wasformed by using a carding machine ("H2DS" manufactured by Ikegami Kikai K.K.). Theformed web was laminated in layers with a layering machine ("IK30-2" manufactured byIkegami Kikai K.K.), and the laminate was produced into a PET nonwoven fabric boardNHA-1 having a dimension of 900 mm x 900 mm x 5 mm and a cloth thickness of 350g / m2 by using a nonwoven fabric needle punching machine ("NL21" manufactured byFehrer AG).

[0082] The produced nonwoven fabric board NHA-1 was applied to a wood dryingapparatus to evaluate the drying of wood as follows.

[0083] An IF steam type wood drying apparatus (manufactured by HildebrandHolztechnik GmbH) was used as the wood drying apparatus. In the IF steam type wooddrying apparatus, an air blower is installed in a drying chamber, and drying isimplemented by circulating steam with its humidity controlled by a dry-wet temperaturesensor into the chamber by using the air blower.

[0084] The produced nonwoven fabric board NHA-1 was installed without gaps in theinside (wall surfaces and ceiling) of a drying chamber of an IF steam type wood dryingapparatus, 170 pieces of wood having a dimension of 2300 mm x 82 mm x 82 mm and200 pieces of wood having a dimension of 1150 mm x 82 mm x 82 mm were placed ona moisture content sensor and then installed in the drying chamber, steam drying wasperformed for 1085 hours, and the changes in the water content of the wood (material tobe dried) were measured. Steam drying was performed by combining an operation ofsupplying steam having a humidity of 100% for a predetermined time in a state in whichthe temperature was maintained at 80°C, and an operation of supplying steam having ahumidity of less than 100% for a predetermined time in a state in which the temperaturewas kept lower than 80°C.

[0085] Next, steam drying of wood was carried out under the same conditions asdescribed above, except that the nonwoven fabric board NHA-1 was removed. The resultsof changes in the moisture content are shown in FIG. 9.

[0086] Furthermore, for the wood after steam drying, the presence or absence of surfacecracking and deformation was evaluated. The results are shown in Table 5.

[0087] [Table 5]

[0088] From FIG. 9, it could be confirmed that when the nonwoven fabric board NHA-1was installed, the change in the water content was suppressed to a low level as comparedwith the case where the nonwoven fabric board NHA-1 was not installed. As a result, asshown in Table 5, it is conceived that stress attributable to the shrinkage of woodoccurring as a result of a decrease in the water content was suppressed, and damage suchas surface cracking and deformation of wood could be suppressed.

[0089] Since the infrared radiation-emitting resin composition according to the presentinvention includes an infrared radiation-emitting material having a high average value ofemissivity in a predetermined wavelength range, the infrared radiation-emitting resincomposition is suitable as a fiber that is used for clothing materials or the like required tohave heat retaining property and as a material that is used for drying of various materials.

Claims

1. An infrared radiation-emitting resin composition comprising: an infrared radiation-emitting material; and a resin, wherein the infrared radiation-emitting material includes a titanium dioxide, a calcined hydrotalcite-like compound, and a nano-sized diamond, in the infrared radiation-emitting material, a mass ratio between the titanium dioxide and the calcined hydrotalcite-like compound is 60:40 to 90:10, and a content of the nano-sized diamond is 0.01 parts by mass or more and 0.5 parts by mass or less with respect to 100 parts by mass of a sum of the titanium dioxide and the calcined hydrotalcite-like compound.

2. The infrared radiation-emitting resin composition according to claim 1, wherein the infrared radiation-emitting resin composition has a plate shape, a tubular shape, a sheet shape, or a fibrous shape, in all of which the infrared radiation-emitting material is dispersed in the resin.

3. The infrared radiation-emitting resin composition according to claim 1 or claim 2, wherein an average particle size of the titanium dioxide is 10 nm or more and 1000 nm or less.

4. The infrared radiation-emitting resin composition according to any one of claims 1 to 3, wherein an average particle size of the calcined hydrotalcite-like compound is 10 nm or more and 1000 nm or less.

5. The infrared radiation-emitting resin composition according to any one of claims 1 to 4, wherein an average particle size of secondary particles of the nano-sized diamond is 5 nm or more and 200 nm or less.