Heating device

Abstract

To provide a heating implement which is good in recovery of bulkiness after unsealing and is high in fitness and feel of use immediately after use.SOLUTION: The heating implement (1) includes a surface sheet (5) positioned on a side close to the skin of a user, a back sheet (6) positioned on a side far from the skin of the user, and a heating element (3) held between the sheets (5, 6). The heating element (3) contains an oxidizable metal, a carbon material, an electrolyte and water and is constituted so as to generate steam from the heating element itself accompanied by heat generation. The surface sheet (5) is composed of an air-permeable fiber sheet. The surface sheet (5) comprises fibers containing at least a PET resin. In addition, the top sheet contains first fibers having a fiber diameter of more than 15 μm as measured by scanning electron microscope observation in a plan view thereof.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heating device. [Background technology]

[0002] The present applicant has previously proposed a water vapor generating thermal sheet for eyes that can supply warm water vapor to the eyes and the area around the eyes (see Patent Document 1). This water vapor generating thermal sheet for eyes has a first moisture-permeable sheet and a second moisture-permeable sheet on the side facing the wearer's skin, and a water vapor-generating composition is sequentially covered by the first moisture-permeable sheet and the second moisture-permeable sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US2004 / 035410A1 Summary of the Invention

[0004] The present invention relates to a heating device. The heating device preferably comprises a top sheet located closer to the user's skin, a back sheet located farther from the user's skin, and a heating element held between the top sheet and the back sheet. The heating element preferably contains an oxidizable metal, a carbon material, an electrolyte, and water. The heating element is preferably configured to generate steam from the heating element itself as it generates heat. The surface of the topsheet facing the skin is preferably made of a breathable fiber sheet containing fibers containing at least polyethylene terephthalate resin. The topsheet preferably contains first fibers having a fiber diameter of more than 15 μm when measured in plan view by scanning electron microscope observation. [Brief explanation of the drawings]

[0005] [Figure 1]FIG. 1 is a plan view showing an embodiment of the heating device of the present invention. [Figure 2] FIG. 2 is an exploded perspective view of the heating device shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the horizontal direction, which is the longitudinal direction, of the heating implement shown in FIG. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the heating device shown in FIG. [Figure 5] FIG. 5 is an enlarged cross-sectional view of another embodiment of the heating device taken along the lateral direction. [Figure 6] FIG. 6 is a schematic diagram of a device for measuring the amount of steam generated from a heating device. [Figure 7] FIG. 7 is a plan view showing another embodiment of the heating device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0006] The heating device described in Patent Document 1 is typically packaged in a compressed state within a packaging material, which means that the sheet material that makes up the heating device is crushed, leaving room for improvement in terms of the recovery of the bulkiness that appears in the sheet material immediately after production. As a result, there is also room for further improvement in the fit and feel of the heating device when in use, which are due to the bulkiness of the sheet material.

[0007] Therefore, the present invention relates to a heating implement that has good bulk recovery after opening, and provides a good fit and comfortable feel immediately after use.

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on preferred embodiments with reference to the drawings. The heating device of the present invention is used to apply heat to an object to be heated by contacting the object to be heated during use.

[0009] One embodiment of the heating device of the present invention is shown in Figure 1. The heating device 1 shown in the figure is a so-called eye mask type, which is placed in contact with both eyes of a person to be heated when in use, to apply heat to the eyes and the surrounding area. The heating device 1 is designed to generate steam heated to a predetermined temperature, which can provide heat to the object to be heated. In the following explanation, unless otherwise specified, the object to be heated will be the user's skin or eyes.

[0010] As shown in Figure 1, the heating device 1 comprises a main body 2 that is elongated in the horizontal direction X and has a shape that covers both eyes of the user when in use, a heating element 3 held within the main body 2, and a pair of ear loops 4, 4. The ear hooks 4 are provided at both outer end regions of the main body 2 in the lateral direction X and can be turned outward in the lateral direction X. This allows the ear hooks 4, 4 to be hung on the user's ears, respectively, so that the main body 2 can keep covering both of the user's eyes. From the viewpoint of improving wearability, it is preferable that the sheet material constituting the ear hook part 4 is a stretchable sheet. In the following explanation, the direction corresponding to the longitudinal direction of the heating device 1 is also referred to as the horizontal direction X, and the direction perpendicular to the horizontal direction X is also referred to as the vertical direction Y.

[0011] Figure 2 shows an exploded perspective view of the heating device 1. Figure 3 shows a cross-sectional view along the lateral direction X (longitudinal direction) of the heating device 1. The main body 2 of the heating device 1 shown in these figures has a long dimension in one direction. The main body 2 is flat and includes a top sheet 5 located on the side closest to the user's skin and a back sheet 6 located on the side farther from the user's skin. The top sheet 5 preferably constitutes the surface that comes into contact with the object to be heated, such as both eyes of a human, when the heating device 1 is in use. The back sheet 6 is the surface farthest from the user's skin and forms the outer surface of the heating device 1. That is, in Figures 2 and 3, the upper side is the side closer to the user's skin, and the lower side is the side farthest from the user's skin.

[0012] The top sheet 5 and the back sheet 6 shown in Figures 2 and 3 are superimposed and bonded to each other with an adhesive 7 such as a hot melt adhesive, so that two heating elements 3, 3 are housed between the two sheets 5, 6 spaced apart from each other in the lateral direction X. Of the top sheet 5 and the back sheet 6, at least the surface of the top sheet 5 that faces the object to be heated, such as the skin (hereinafter also referred to as the "skin-facing surface"), is preferably made of a breathable fiber sheet, and it is more preferable that the entire top sheet 5 is made of a fiber sheet. Furthermore, the top sheet 5 and the back sheet 6 may each independently have a single-layer structure or a multi-layer structure. A detailed description will be given later of each of the sheets 5 and 6. The fiber sheet is an assembly of constituent fibers that are maintained in a sheet shape by at least one of entanglement, fusion, and bonding.

[0013] The heating element 3 held between the top sheet 5 and the back sheet 6 in the main body 2 is configured to react with oxygen in the air to generate heat, and as the heat is generated, generate water vapor heated to a predetermined temperature. In other words, the heating element 3 of the present disclosure generates steam from the heating element 3 itself as it generates heat. Specifically, the heating element 3 includes a heating portion 3a containing an oxidizable metal that generates heat through an oxidation reaction with oxygen in the air, a carbon material such as activated carbon that serves as a catalyst for the oxidation reaction, an electrolyte, and water. The oxidizable metal and the carbon material are preferably both in the form of powder.

[0014] The heat generating portion 3a may be, for example, a heat generating sheet made of a fiber sheet containing a fiber material in addition to an oxidizable metal, a carbon material, an electrolyte, and water, or one having a layer of a paste-like or powder-like heat generating composition containing an oxidizable metal, a carbon material, an electrolyte, and water. From the viewpoint of retaining a sufficient amount of water that can increase the amount of water vapor generated by the heat generated by the heat generating element 3, the heat generating element 3 preferably further comprises a water retention agent layer containing a water-retaining agent such as a water-absorbent polymer adjacent to the heat generating portion 3a. Alternatively, it is also preferable that a water retention agent be mixed into the heat generating sheet or the heat generating composition.

[0015] The heat-generating sheet and heat-generating composition may be used alone, or at least one of the heat-generating sheet and heat-generating composition may be contained in a bag made of multiple sheets bonded together. Materials for the heat-generating sheet and heat-generating composition include, for example, materials described in JP-A Nos. 2003-102761 and 2006-340928.

[0016] The cross-sectional view in Figure 3 shows the fixed state of the flat heating element 3 formed by housing the heating part 3a in a bag 3b. The heating element 3 shown in the figure is fixed by adhesive fixing parts 7a, 7a formed by adhesive 7 between the outer surface of the bag 3b and the inner surface of the back sheet 6 of the heating device 1, and other surfaces are not fixed to the back sheet 6. Each adhesive fixing part 7a, 7a is provided in the central region of the heating device 1 in the horizontal direction X and extends along the vertical direction Y of the heating device 1. With this configuration, when using the heating device 1, the heating element 3 is arranged so as to be highly flexible and in close contact with the heating target, such as the user's eyes and the vicinity thereof, allowing heat to be efficiently applied to the heating target.

[0017] Returning to Figure 2, the ear hooking part 4 shown in the figure is made of a sheet material, and the sheet material has an insertion part 4A formed therein that extends in the lateral direction X. The insertion part 4A is a hole through which the ear passes when the ear hooking part 4 is hung on the ear. Alternatively, the insertion part 4A may be formed as a through slit or the like through which the ear can be passed. 2 and 4, the ear hooks 4 are joined at both outer edge regions in the lateral direction X to the outer surface of the topsheet 5 of the main body 2, thereby forming a joining region 9 where the main body 2 and the ear hooks 4 are joined. The joining region 9 also functions as a folding region when the ear hooks 4 are turned over around the joining end 9s.

[0018] 4 is a cross-sectional view showing one embodiment of the arrangement of the heating element 3, top sheet 5, back sheet 6, and joint area 9. The joint area 9 between the main body 2 and the ear hooking part 4 shown in FIGS. 2 and 4 is continuously joined from the joint end 9s, which is the inner end of the joint area 9 in the horizontal direction X, to the outer end of the main body 2 in the horizontal direction X, and has a semi-elliptical shape. As shown in Fig. 4, the bonded region 9 is formed by bonding the topsheet 5 and the ear hooking portion 4. The bonded region 9 also functions as a folding portion when the ear hooking portion 4 is turned over around the bonded end 9s. The bonded region 9 shown in Figs. 2 and 4 is formed by continuous bonding, but may instead be formed by intermittent bonding.

[0019] In the heating device 1 having the above-mentioned configuration, the top sheet 5, which is the part that comes into contact with the object to be heated during use, preferably contains fibers having a predetermined configuration. In the following explanation, a breathable fiber sheet, which is a suitable embodiment of the top sheet 5, will be used as an example.

[0020] Specifically, it is preferable that the fibers constituting the topsheet 5 contain at least polyethylene terephthalate (PET) resin. In other words, the topsheet 5 is an aggregate of fibers that contain at least PET resin as one of the constituent fibers. Fibers containing at least PET resin tend to be more rigid than fibers containing other thermoplastic resins, so by using a surface sheet 5 containing fibers containing at least PET resin, even if the heating device 1 is compressed in the sheet thickness direction during pre-use processes such as packaging and distribution, the bulk of the surface sheet 5 will easily and quickly recover when the packaging bag is opened and the compressed state is released, resulting in high flexibility, fit and feel immediately after use.

[0021] The topsheet 5 contains first fibers having a predetermined fiber diameter. Specifically, the first fibers contained in the topsheet 5 preferably have a fiber diameter of more than 15 μm, more preferably 20 μm or more, even more preferably 25 μm or more, and preferably 60 μm or less, more preferably 50 μm or less, even more preferably 45 μm or less, and even more preferably 40 μm or less. In another embodiment, the diameter can be even more preferably 30 μm or less. By having the first fibers have such a fiber diameter, even if the heating device is compressed in the thickness direction, for example when it is contained in a packaging bag, the bulk of the surface sheet that makes up the heating device will recover immediately after the compression is released, for example by removing it from the packaging bag, improving the fit when in use.

[0022] The "constituent fibers containing at least PET resin" may be the first fibers themselves having the above-mentioned fiber diameter, or may be fibers other than the first fibers constituting the topsheet, or may be all of the first fibers and other fibers constituting the topsheet. From the viewpoint of improving flexibility, fit, and usability, it is preferable that at least the first fibers contain PET resin. In this case, the proportion of PET resin contained in the first fibers is preferably 20% by mass or more, more preferably 40% by mass or more, even more preferably 70% by mass or more, and most preferably 100% by mass.

[0023] The fiber diameter of the first fibers contained in the topsheet 5 can be measured, for example, by observing the topsheet in a plan view with a scanning electron microscope (SEM) as follows. This fiber diameter measurement method is commonly applied as a method for measuring the fiber diameter of all fibers described in this specification. First, a histogram (hereinafter simply referred to as a "histogram") of the frequency of the number of fibers and the distribution of fiber diameters is created to determine whether the topsheet contains fibers of only one type of fiber diameter or whether it also contains fibers of multiple fiber diameters. Specifically, a measurement sample of the surface sheet to be measured is obtained by spraying a cold spray onto the heating implement to solidify the adhesive and then carefully peeling it off, or by cutting it directly from the heating implement. This measurement sample should be 2 cm x 2 cm in size. The measurement sample should be designed so that the skin-facing side and the side facing away from the user's skin (hereinafter also referred to as the "non-skin-facing side") can be distinguished by any method. The method of removing the measurement sample from the surface sheet described above is common to other methods in this disclosure.

[0024] Next, the fiber diameter and number of fibers are measured from this measurement sample to create a histogram. The fiber diameter and number of fibers are derived from a two-dimensional image obtained by observing the fibers in a plan view of one side of the measurement sample using an SEM at a magnification of, for example, 2000 times. The number of fibers is measured by counting each continuous fiber within the obtained two-dimensional image as one fiber. The SEM observation position is then changed and repeated observations are made until the number of fibers reaches 100 or more. Note that this observation can also be performed using image analysis software. For example, Photoshop (manufactured by Adobe Inc.) can be used as the image analysis software. The fiber diameter is the maximum diameter measured when a line perpendicular to the longitudinal direction of the fiber is drawn on the fiber, excluding defects such as fiber clumps, fiber intersections, and polymer droplets.

[0025] The above-mentioned measurements are carried out on the skin-facing surface of the measurement sample, the width of the fiber diameter classes for creating the histogram is selected from the range of 0.1 to 0.5 μm, and a histogram of the frequency of the number of fibers and the distribution of fiber diameters is created based on the measurement results. If the created histogram shows only one peak in the fiber diameter distribution, it is determined that the measurement side of the topsheet is composed of only a single type of fiber. Alternatively, if the fiber diameter distribution shows two or more peaks, it is determined that the measurement side of the topsheet is composed of multiple types of fiber. The peak is the position of the fiber diameter at the apex where the frequency of the fiber count changes from positive to negative.

[0026] Whether the surface sheet has a single or multiple fiber layers can be determined, for example, by observing the cross section of the measurement sample using a microscope or SEM, and checking the presence or absence of fiber layers and their boundaries based on differences in fiber diameter and fiber structure, or by dyeing the fibers, etc. If it is difficult to visually confirm whether or not there are multiple fiber layers, a histogram is also created on the other side (non-skin-facing side) of the measurement sample using the above method, and the shape of the histogram on one side (skin-facing side) of the measurement sample is compared with the shape of the histogram on the other side of the measurement sample. If the number of peaks or the positions of their appearance are different, it is determined that there are multiple fiber layers. On the other hand, if the number of peaks and the positions of their appearance are the same, it is determined that there is a single fiber layer.

[0027] Using the method described above, it is determined whether the topsheet contains only the first fibers or whether it further contains fibers other than the first fibers. If there is only one peak in the fiber diameter distribution, the position of the fiber diameter at which the peak occurs in the histogram is determined as the fiber diameter of the first fibers. If there are two or more peaks in the fiber diameter distribution, the position of the fiber diameter indicated by the peak located on the side with the largest fiber diameter is determined as the fiber diameter of the first fibers.

[0028] Generally, heating devices that utilize the heat generated by the oxidation reaction of iron are sealed in a packaging bag that blocks the intrusion of outside air in an oxygen-free and compressed state before use, in order to block contact with oxygen and prevent the unintended oxidation reaction of iron from progressing. In this case, even if the top sheet is configured to exhibit flexibility and fit during production, the sheet is likely to be compressed in the thickness direction when or after the heating device equipped with the top sheet is sealed in the packaging bag, or during distribution of the heating device sealed in the packaging bag, and the flexibility and fit due to the top sheet may not be exhibited as designed, leaving room for improvement.

[0029] According to this embodiment, by using fibers having a predetermined fiber diameter and containing PET resin as the constituent fibers of the top sheet 5, the high rigidity of PET exhibits compression resistance, and even if the sheet is compressed in the thickness direction during pre-use processes such as packaging and distribution, the bulk of the top sheet easily recovers when the packaging bag is opened and the compressed state is released, resulting in a high fit and feel immediately after use, and a pleasant texture against the skin. In addition, the heat and steam generated during use, as well as the air warmed by the heat, further increase the interfiber distances of the fibers that make up the topsheet 5, efficiently increasing the bulk of the sheet. As a result, the heating device 1 maintains a high level of flexibility and fit over a long period of time, from the start to the end of use.

[0030] In order to combine the quick recovery of bulkiness of the topsheet 5 with flexibility, fit, and feel during use, while suppressing fiber fuzzing and improving the feel of the surface that comes into contact with the skin, it is preferable that the topsheet 5 further contain, in addition to the above-mentioned first fibers, one or more types of other fibers that are different in type from the first fibers.

[0031] Examples of the fiber configuration of the topsheet 5 include the following: (i) a configuration in which the first fibers and fibers other than the first fibers are uniformly mixed in the area that contacts the heated object such as the skin, (ii) a configuration in which, when the area that contacts the heated object such as the skin is viewed from above, the area is composed of an area where only the first fibers are present and an area where only fibers other than the first fibers are present, or (iii) a configuration in which the topsheet 5 has a multilayer structure having two or more fiber layers, and the first fibers are contained in only one of the fiber layers.

[0032] Of these, from the viewpoint of suppressing fiber fuzzing, improving the feel of the sheet, and more effectively exhibiting flexibility and fit, it is preferable that the topsheet 5 be in the form shown in (iii) above. From a similar viewpoint, it is preferable that the fiber sheet constituting the top sheet is in a state in which the sheet form is maintained by at least one of fusion and entanglement of the fibers so that the constituent fibers have contact portions where they are in contact with each other. In particular, the above-mentioned sheet form is preferably made of a nonwoven fabric. Examples of nonwoven fabrics with entangled fibers include spunlace nonwoven fabrics, air-through nonwoven fabrics, needle-punched nonwoven fabrics, chemically bonded nonwoven fabrics, and thermally bonded nonwoven fabrics. To achieve the above-mentioned embodiment (iii), a method can be used in which two or more fiber webs or nonwoven fabrics are entangled or fused together. For example, in the case of an air-through nonwoven fabric, the contact areas described above include not only areas where the constituent fibers are simply in contact with each other and entangled, but also areas where some of the fibers are fused together, which makes it easier for the constituent fibers to be fixed together, and is advantageous in that fluffing and shedding of the constituent fibers are reduced. In addition, the nonwoven fabric or its constituent fibers may be surface-treated with silicone, a surfactant, or the like.

[0033] In addition to the nonwoven fabrics described above, foam sheets made from thermoplastic resins such as polyethylene and polyurethane can also be used. These sheet materials can also be used by mixing multiple fibers with different fiber materials, fiber diameters, degrees of crimp, etc., or by combining multiple sheet materials to achieve desired properties.

[0034] In a preferred embodiment of the topsheet 5, when the topsheet 5 has a multi-layer structure having two or more fiber layers, it preferably has at least a first fiber layer 51 containing first fibers and a second fiber layer 52 containing fibers other than the first fibers that have a fiber diameter different from that of the first fibers, as shown in Fig. 5. Specifically, as in this embodiment, it is preferable to have a second fiber layer 52 containing second fibers that are fibers with a smaller fiber diameter than the first fibers. In addition, it is preferable that the first fiber layer 51 does not contain the second fibers, and the second fiber layer 52 does not contain the first fibers. That is, it is preferable that the topsheet 5 has at least a fiber layer containing the first fibers and a fiber layer containing fibers other than the first fibers. By providing multiple fiber layers containing fibers of different fiber diameters in this way, the heating device can provide the desired function for each fiber layer, with the fiber layer containing the first fiber providing the function of restoring sheet bulkiness and the fiber layer containing the second fiber providing the topsheet with a good feel and texture. As a result, the topsheet 5 can be configured to efficiently and simultaneously provide the multiple functions described above, and the manufacturing efficiency of such topsheets is further improved.

[0035] For ease of explanation, the following description will be given taking as an example the form of a two-layer topsheet 5 (see FIG. 5) in which a first fiber layer 51 and a second fiber layer 52 are arranged adjacent to each other as shown in FIG. 5 . However, the number of fiber layers is not particularly limited as long as the effects of the present invention are achieved. For example, in an example embodiment (Example 1), the first fiber layer 51 and the second fiber layer 52 are arranged adjacent to each other, and one or more other fiber layers can be provided on the outer surface of at least one of the first fiber layer 51 and the second fiber layer. Alternatively, in another example embodiment (Example 2), one or more other fiber layers can be further provided between the first fiber layer 51 and the second fiber layer 52. The fibers contained in adjacent fiber layers preferably have different fiber diameters. Therefore, in Example 1, when the third fiber layer is provided on the outer surface of the first fiber layer 51, the fiber diameter of the third fiber layer may be the same as the fiber diameter of the second fiber layer, or may be different from the fiber diameters of the first and second fiber layers.

[0036] For ease of explanation, the topsheet 5 shown in Figure 5 is illustrated with clear boundaries between the fiber layers that make up the topsheet 5, but this is not limited to this. In other words, when the topsheet has a multi-layer structure, the boundaries between the fiber layers may be clear, or the boundaries between the fiber layers may be unclear. In either case, when the topsheet 5 is viewed along the thickness direction, it is preferable that the proportion of the constituent fibers in each fiber layer changes stepwise, continuously, or a combination thereof, from the standpoint of ease of handling during the manufacture and use of the topsheet.

[0037] In the present disclosure, "not containing fibers" means that the fibers are not intentionally contained in the fiber layer, and encompasses both the complete absence of the fibers in the fiber layer and the unavoidable inclusion of fibers in the fiber layer. In the latter case, for example, a first fiber constituting the first fiber layer 51 crosses the boundary between the fiber layers and unintentionally penetrates into the second fiber layer, resulting in the unavoidable inclusion of other fibers.

[0038] When the topsheet 5 has at least a first fiber layer 51 and a second fiber layer 52, the fiber diameter of the second fibers constituting the second fiber layer 52 is preferably 6 μm or more, more preferably 10 μm or more, even more preferably 13 μm or more, and is preferably 30 μm or less, more preferably 25 μm or less, even more preferably 20 μm or less, and particularly preferably 17 μm or less. It is also preferable that the fiber diameter of the second fibers is smaller than the fiber diameter of the first fibers. By allowing the second fibers to have such a fiber diameter, the stiffness of the fibers is reduced, and when the topsheet comes into contact with the skin, a pleasant feel and smooth texture are achieved. The fiber diameter of the second fibers can be measured in the same manner as for the fiber diameter of the first fibers by observing the topsheet in a plan view with a scanning electron microscope.

[0039] Furthermore, when the topsheet 5 has at least a first fiber layer 51 and a second fiber layer 52, it is preferable that the first fiber layer 51 be arranged on the side farthest from the user's skin when the heating device is in use, as shown in Figure 5. Also, as shown in the same figure, it is preferable that the second fiber layer 52 be arranged on the skin-contacting side, which is the side that comes into direct contact with the user's skin when in use. That is, the second fiber layer 52 constitutes the skin-facing surface and is preferably disposed so as to abut against the skin of the user. In addition, the first fiber layer 51 is preferably disposed in a position that does not contact the user's skin. In the embodiment shown in Figure 5, the first fiber layer 51 forms the non-skin-facing surface of the topsheet 5, and is disposed in a position closest to the heating element 3 and adjacent to the heating element 3. By arranging each fiber layer in this manner, direct contact of the first fiber, which has a relatively high rigidity due to the inclusion of PET resin, with the user's skin is reduced, allowing the user to perceive the softness and smooth texture of the surface sheet.

[0040] When the topsheet 5 has a first fiber layer 51, the first fiber layer 51 preferably further contains, in addition to the first fibers, third fibers that are thinner than the first fibers and thicker than the second fibers. That is, the first fiber layer 51 preferably contains a plurality of fibers including at least the first fibers and the third fibers, and more preferably is made up of only the first fibers and the third fibers, excluding fibers that are inevitably mixed in, and does not contain the second fibers. By including third fibers having such a predetermined fiber diameter relationship in the first fiber layer 51, the flexibility of the surface sheet can be increased compared to a configuration consisting only of the highly rigid first fibers, further improving the fit during use.

[0041] When the first fiber layer 51 further contains third fibers, the fiber diameter of the third fibers is preferably 15 μm or more, more preferably 18 μm or more, even more preferably 20 μm or more, provided that the fiber diameter is smaller than the fiber diameter of the first fibers and larger than the fiber diameter of the second fibers, and is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and even more preferably 24 μm or less. By having such a fiber diameter, the third fibers have lower rigidity than the first fibers, which have a relatively large fiber diameter, and this increases the flexibility of the topsheet, further improving the feel and comfort of the heating device. The fiber diameter of the third fibers can be measured in the same manner as for the fiber diameter of the first fibers by observing the topsheet in a plan view with a scanning electron microscope. When the first fiber layer 51 contains the first fibers and the third fibers, the two fibers may be present in a mixed state, or the first fiber layer 51 may have a multilayer structure consisting of a layer essentially consisting of the first fibers and a layer essentially consisting of the third fibers.

[0042] In the following, as a preferred embodiment of the topsheet 5, when it has a two-layer structure consisting of a first fiber layer 51 constituting the non-skin-facing side and a second fiber layer 52 constituting the skin-facing side, the fiber diameters of the constituent fibers can be measured, for example, by the following method. First, confirm that there are two fiber layers using the measurement method described above, and create a histogram. For example, when the first fiber layer 51 is composed only of the first fiber, the histogram on the skin-facing surface of the measurement sample has only one peak, and the position of the fiber diameter indicated by the apex of the peak is the fiber diameter of the first fiber. On the other hand, when the first fiber layer 51 is composed of the first fiber and the third fiber, the histogram on the skin-facing surface of the measurement sample has two peaks, and the position of the fiber diameter indicated by the peak on the larger fiber diameter side is the fiber diameter of the first fiber, and the position of the fiber diameter indicated by the peak on the smaller fiber diameter side is the fiber diameter of the third fiber. Furthermore, when the second fiber layer 52 is composed only of the second fiber, the histogram on the non-skin-facing side of the measurement sample has only one peak, and the position of the fiber diameter indicated by the apex of that peak is taken as the fiber diameter of the second fiber.

[0043] From the viewpoint of improving flexibility and fit due to the recovery of bulkiness when the heating device 1 is in use, the mass ratio of the third fiber to the first fiber layer 51 in the surface sheet is preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 40% by mass or more, and is preferably 90% by mass or less, more preferably 75% by mass or less, even more preferably 60% by mass or less. From a similar viewpoint, the mass ratio of the first fibers to the first fiber layer 51 in the top sheet is preferably 10 mass% or more, more preferably 25 mass% or more, even more preferably 40 mass% or more, and preferably 90 mass% or less, more preferably 75 mass% or less, even more preferably 60 mass% or less.

[0044] On the other hand, the mass ratio of the second fibers to the second fiber layer 52 in the topsheet is preferably 80 mass% or more, more preferably 90 mass% or more, even more preferably 95 mass% or more, and even more preferably 100 mass%. In other words, the second fiber layer 52 is preferably composed only of the second fibers, excluding fibers that are unavoidably mixed in. With this configuration, when the topsheet comes into contact with the skin, the second fibers, which have a relatively low rigidity, tend to come into contact with the skin, effectively achieving a pleasant feel and smooth texture.

[0045] The proportions of the first fibers, the second fibers, and the third fibers that make up the topsheet 5 can be measured, for example, as follows. The ratios of the first and third fibers were determined by randomly selecting 100 fibers from the first fiber layer 51 using a digital microscope and measuring their widths in a planar view as fiber diameters. The arithmetic mean of the 100 fiber diameters was calculated, and fibers whose fiber diameters differed from the arithmetic mean by 2 μm or more were determined to be different fibers. Fibers whose fiber diameters were larger than the arithmetic mean were designated as first fibers, and fibers whose fiber diameters were smaller than the arithmetic mean were designated as third fibers. Fibers whose fiber diameters were less than 2 μm smaller than the mean were designated as first fibers. After measuring the fiber diameters, the fibers were sorted into first and third fibers, and the weights of each were measured to calculate the ratios of the first and third fibers per 100 randomly selected fibers. Next, the first fiber layer 51 and the second fiber layer 52 were each cut into 1 cm x 1 cm pieces, and the weights of each were measured to calculate the ratios of the first fiber layer 51 and the second fiber layer 52. The ratios of the first fiber, second fiber, and third fiber were calculated from the above measurements.

[0046] Preferred constituent materials for the first, second, and third fibers are described below. From the viewpoints of convenience and cost in manufacturing the heating device, it is preferable that the first, second, and third fibers each contain a thermoplastic resin.

[0047] Thermoplastic resins used for each fiber include, independently, polyester resins such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polybutylene terephthalate (PBT); ethylene-α-olefin copolymers such as ethylene-propylene copolymers; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, and polystyrene; acrylic resins such as polyacrylic acid, polyacrylic acid esters, polymethacrylic acid, and polymethacrylic acid esters; polyamide resins; and combinations thereof. Other examples include those described in JP-A-9-296325.

[0048] When the above-mentioned thermoplastic resins are used in combination, two or more thermoplastic resins having different constituent components may be present in the fiber in a mixed state, or the thermoplastic resins may be present in the fiber in a state where the boundary between them is clear, such as in the case of a concentric sheath-core or eccentric sheath-core composite fiber or a side-by-side composite fiber containing two types of thermoplastic resins having different constituent components. Examples of the core / sheath combination in core-sheath fibers or the first resin / second resin combination in side-by-side composite fibers include fibers made of combinations of polypropylene / polyethylene, polypropylene / ethylene-propylene copolymer, polyethylene terephthalate / polyethylene, polyethylene terephthalate / polypropylene, etc. These can be used alone or in combination. In the present invention, the type of thermoplastic resin constituting the fiber can be determined by measuring the melting point by differential scanning calorimetry (DSC).

[0049] As described above, the first fiber preferably contains at least PET resin, more preferably is a fiber made of only PET resin, or is a fiber made of only PET resin and a thermoplastic resin other than PET resin, and even more preferably is a fiber made of only PET resin. With this configuration, when the heating device is released from its compressed state, the bulk of the topsheet easily recovers due to the rigidity of the first fibers, and a thickness suitable for effective softness can be maintained. In addition, the amount of change in the thickness of the topsheet increases, improving the fit during use.

[0050] The second fibers preferably contain PE resin, more preferably contain PET resin or PP resin in addition to PE resin, and further preferably are fibers made only of PE resin and PET resin or PP resin. This configuration reduces fiber fuzzing in the topsheet, providing a pleasant feeling of smoothness to the skin and further improving the feel. This is also advantageous in that when heat is applied during the manufacturing process of the topsheet, such as by air-through processing, the second fibers having the above-mentioned configuration heat-fuse to each other, reducing fiber fuzzing in the resulting sheet. Furthermore, even when the topsheet is transported during the manufacturing process of the heating device, the generation of peeled fiber fragments and fallen fiber fragments from the topsheet, as well as fine particles derived from the constituent fibers (hereinafter collectively referred to as "paper dust"), and the adhesion of paper dust to the sheet surface can be reduced, preventing the sheet surface from becoming rough and resulting in a heating device with a pleasant feel. In addition, it is possible to reduce the amount of sheet waste and increase production efficiency.

[0051] When the first fibers further contain a thermoplastic resin other than PET resin, it is more preferable that the first fibers be core-sheath fibers made of PET resin and another thermoplastic resin, from the viewpoint of further improving the feel of the sheet and the usability of the heating device due to improved flexibility and reduced fiber fuzzing, while reducing the generation and adhesion of paper dust. Furthermore, from the viewpoint of further improving the feel of the sheet and the comfort of the heating device due to improved flexibility and reduced fiber fuzzing while reducing the generation and adhesion of paper dust, it is even more preferable that the second fiber be a core-sheath fiber made of PE resin and other thermoplastic resin.

[0052] The third fibers preferably contain a thermoplastic resin other than PET resin, more preferably PE resin, even more preferably PET resin or PP resin in addition to PE resin, and even more preferably consist of only PP resin and PE resin. It is also preferable that the second fibers and the third fibers contain resins whose components are different from each other. This configuration reduces fiber fuzzing in the topsheet, providing a pleasant feeling of smoothness to the skin and further improving the feel when used. This is also advantageous in that when heat is applied during the topsheet manufacturing process, such as by air-through processing, the second fibers having the above-mentioned configuration are thermally fused together, reducing fiber fuzzing in the resulting sheet. Furthermore, even when the topsheet is transported during the manufacturing process of the heating device, the generation of paper dust and its adhesion to the sheet surface can be reduced, preventing the sheet surface from becoming rough and resulting in a heating device with a pleasant feel. In addition, it is possible to reduce the amount of sheet waste and increase production efficiency.

[0053] When the third fibers further contain a thermoplastic resin other than PET resin, the third fibers are more preferably core-sheath fibers made of PP resin and another thermoplastic resin, from the viewpoint of further improving the feel of the sheet and the comfort of the heating device due to improved flexibility and reduced fiber fuzzing while reducing the generation and adhesion of paper dust. In this case, it is preferable that the third fibers have a core made of PP resin and a sheath made of PE resin.

[0054] As long as the effects of the present invention are achieved, in addition to or instead of the above-mentioned fibers, the topsheet 5 may contain fibers other than the fibers containing thermoplastic resin. Examples of such other fibers include natural fibers such as wood pulp, cotton, and hemp, and regenerated fibers such as rayon and cupra, etc. These may be used alone or in combination.

[0055] The following describes matters that are commonly applicable to the heating devices of the present disclosure. The sheet materials that can be used for the heating element 3, ear loops 4, top sheet 5, and back sheet 6 can be appropriately selected taking into consideration their breathability, moisture permeability, texture, stretchability, strength, and properties such as prevention of leakage of the constituent materials of the heat-generating sheet and heat-generating composition. For example, fiber sheets such as nonwoven fabric, woven fabric, and paper, resin foam sheets, metal sheets, or combinations of these may be used.

[0056] As a sheet material with high breathability, a meltblown nonwoven fabric is preferably used, and as a sheet material for improving the texture, an air-through nonwoven fabric or a thermal bond nonwoven fabric is preferably used. Examples of sheet materials used to achieve stretchability include air-through nonwoven fabrics, spunbond nonwoven fabrics, and thermal-bond nonwoven fabrics containing synthetic fibers such as polyesters such as polyethylene terephthalate, polyethylene, and polypropylene. As the sheet material used for the purpose of imparting strength, spunbond nonwoven fabric, spunlace nonwoven fabric, needle-punched nonwoven fabric, chemical-bond nonwoven fabric, etc. are preferably used.

[0057] In addition to or instead of the nonwoven fabrics described above, it is possible to use nonwoven fabrics that have been surface-treated with silicone, surfactants, etc., or foam sheets made from thermoplastic resins such as polyethylene or polyurethane. These sheet materials can also be used by mixing multiple fibers with different fiber materials, fiber diameters, degrees of crimp, etc., or by combining multiple sheet materials to achieve desired properties. The heating element 3, ear hook portion 4, top sheet 5 and back sheet 6 may be a single structure consisting of only one sheet material, whether single-layer or multi-layer, or may be a laminated structure consisting of two or more types of sheet material layered on top of each other.

[0058] As described above, a fiber sheet is preferably used for the topsheet 5, and from the viewpoint of easily obtaining a fiber sheet containing a thermoplastic resin, at least one of a needle-punched nonwoven fabric, an air-through nonwoven fabric, a spunbonded nonwoven fabric, and a chemical-bonded nonwoven fabric can be preferably used. When the topsheet 5 is a laminate of sheet materials and each sheet material contains crimped fibers, the above-mentioned crimp percentage and number of crimps must be satisfied independently for each sheet material.

[0059] When a breathable fiber sheet is used as the topsheet 5, the air permeability of the topsheet 5 is preferably 0.01 sec / 100 mL or more, more preferably 50 sec / 100 mL or more, and even more preferably 2000 sec / 100 mL or more. The air permeability of the topsheet 5 is preferably 15000 sec / 100 mL or less, more preferably 50000 sec / 100 mL or less, and even more preferably 10000 sec / 100 mL or less. Air permeability is measured according to the method described in JIS P8117. Low air permeability means that it takes less time for air to pass through, and therefore indicates high breathability.

[0060] When a nonwoven fabric is used as the backsheet 6, it is preferable to use a fiber sheet having higher breathability than the topsheet 5. That is, the backsheet 6 preferably has a higher breathability as measured by the method described in JIS P8117 than the topsheet 5. In particular, the higher the breathability of the backsheet 6, the better, and provided that the breathability is higher than that of the topsheet 5, it is preferably 50 sec / 100 mL or more, more preferably 4000 sec / 100 mL or more, and even more preferably 20000 sec / 100 mL or more, and it is even more preferable that the backsheet 6 be a non-breathable sheet.

[0061] When nonwoven fabrics are used as the top sheet 5 and the back sheet 6, the basis weight of the top sheet 5 is 10 g / m2 as the basis weight of the entire sheet. 2 It is preferable that the content is 20 g / m or more. 2More preferably, it is 30 g / m or more. 2 The surface sheet 5 preferably has a basis weight of 200 g / m or more. 2 Preferably, it is 130 g / m or less. 2 More preferably, it is 90 g / m or less. 2 It is more preferable that the following is true: With this configuration, it is possible to achieve both thickness and flexibility of the sheet, and to achieve a good feel and fit.

[0062] When the topsheet 5 has the first fiber layer 51, the basis weight of the first fiber layer 51 is 10 g / m 2 It is preferable that the content is 15 g / m or more. 2 More preferably, it is 20 g / m or more. 2 The basis weight of the first fiber layer 51 is preferably 100 g / m or more. 2 Preferably, it is 80 g / m or less. 2 More preferably, it is 60 g / m or less. 2 It is more preferable that: With this configuration, when the packaging bag is opened and the compressed state is released, the bulkiness of the surface sheet is easily restored, the amount of change in thickness is large immediately after use, and the sheet has a good fit and feel when used, and is pleasant to the touch.

[0063] When the topsheet 5 has the second fiber layer 52, the basis weight of the second fiber layer 52 is 5 g / m 2 It is preferable that the content is 10 g / m or more. 2 More preferably, it is 15 g / m or more. 2 The basis weight of the second fiber layer 52 is preferably 50 g / m or more. 2 Preferably, it is 40 g / m or less. 2 More preferably, it is 30 g / m or less. 2It is more preferable that the following holds true: With this configuration, highly rigid fibers such as the first fibers constituting the first fiber layer 51 are prevented from unintentionally protruding toward the second fiber layer 52 or the skin-facing surface, and a good smoothness of the sheet surface can be obtained at the surface that comes into contact with the heated object such as the skin.

[0064] When the topsheet 5 has the first fiber layer 51, the density of the fibers in the first fiber layer 51 is preferably 1500 fibers / cm 2 Less than 1000 fibers / cm, preferably 1000 fibers / cm 2 More preferably, 700 fibers / cm or less 2 less than 150 lines / cm 2 The above is realistic. With this configuration, the thickness of the sheet increases, and a good fit can be obtained.

[0065] When the topsheet 5 has the second fiber layer 52, the density of the fibers in the second fiber layer 52 is preferably 200 fibers / cm 2 More preferably, 300 fibers / cm 2 More preferably, 400 fibers / cm 2 or more, and preferably 1500 fibers / cm 2 Less than or equal to 1200 fibers / cm, more preferably 2 More preferably, 1000 fibers / cm or less 2 The following is the result. This configuration prevents relatively rigid fibers such as the first and third fibers that make up the first fiber layer 51 from unintentionally protruding toward the second fiber layer 52 or the skin-facing surface, thereby achieving good smoothness on the sheet surface at the contact surface with the heated object such as the skin. In order to obtain such an effect, the density of the fibers in the second fiber layer 52 is preferably higher than the density of the fibers in the first fiber layer.

[0066] The density of the fibers present in the topsheet 5 can be measured by the following method. First, the cross section of the measurement sample obtained by the above method is observed using a microscope or SEM to confirm the difference in fiber diameter and fiber structure, and to confirm that there are two fiber layers. Then, the first fiber layer and the second fiber layer are separated from the measurement sample, and the number of fibers present in the sheet cut into a 1 cm x 1 cm square is observed with an SEM and counted. The number of fibers counted is then divided into 1 cm squares. 2 It is calculated as the density of fibers per unit area.

[0067] In addition, the basis weight of the back sheet 6 is set to 10 g / m2 as a total basis weight from the viewpoint of improving the heat retention of the applicable area during use. 2 It is preferable that the content is 30 g / m or more. 2 The basis weight of the back sheet 6 is more preferably 200 g / m or more. 2 Preferably, it is 150 g / m or less. 2 It is more preferable that:

[0068] It is also preferable that the thickness of the topsheet 5 is within a predetermined range at the start of heat generation. In detail, the thickness of the topsheet 5 at the start of heat generation of the heating device is preferably 1.8 mm or more, more preferably 2.5 mm or more, even more preferably 3.5 mm or more, and preferably 6.0 mm or less, more preferably 5.5 mm or less, even more preferably 5.0 mm or less. Such a thickness means that the bulkiness of the surface sheet 5 can be restored immediately after use, making it possible to improve the flexibility and feel of the heating device immediately after use, as well as improving the fit to the object to be heated.

[0069] Furthermore, the thickness of the surface sheet 5 10 minutes after the heating device starts to generate heat is preferably 1.7 mm or more, more preferably 3.0 mm or more, even more preferably 4.0 mm or more, still more preferably 4.5 mm or more, and preferably 8.0 mm or less, more preferably 7.0 mm or less, even more preferably 6.5 mm or less. Such a thickness means that the bulkiness of the surface sheet 5 can be restored and maintained during use, which allows the heating device to maintain good flexibility and feel on the skin for a long period of time while in use, and improves its fit to the object to be heated.

[0070] The thickness of the topsheet 5 and the amount of increase thereof can be measured by the following method using an unheated heating device 1 that is sealed in a packaging bag or the like. For unheated heating devices that are sealed in a package, etc., 3.7 gf / cm 2 Apply a load of this magnitude to the sheet, measure at least three locations using a constant pressure thickness gauge, etc., and use the arithmetic mean value of the thickness as the sheet thickness T1 (mm) at the start of heat generation. Similarly, measure the sheet thickness after 10 minutes under the same load, and use the arithmetic mean value of the thickness as the sheet thickness T2 (mm) at the end of 10 minutes. At this time, the time required from the start of opening the packaging bag, etc., to bringing the heating device 1 into contact with an oxygen-containing atmosphere such as air, and from the start of opening until the topsheet 5 is spread and placed on a flat table, in other words, the time 30 seconds after the start of opening, is defined as the "start of heat generation time." At this time, it is preferable that the thickness of the topsheet 5 of this embodiment is increased or maintained.

[0071] In this disclosure, "steam is generated" means that the total amount of water vapor generated in 10 minutes, as measured by the following method, is 10 mg / 10 minutes or more. This amount of water vapor can be easily achieved by using, for example, a paste containing an oxidizable metal, a carbon material, and water as the heat generating part 3a. The amount of water vapor generated can be measured using an apparatus 100 having the configuration shown in FIG. 5 . The apparatus 100 includes an aluminum measurement chamber 101 (volume: 4.2 L), an inlet channel 102 communicating with the lower part of the measurement chamber 101, and an outlet channel 103 communicating with the upper part of the measurement chamber 101. The inlet channel 102 allows dehumidified air (humidity less than 2% RH, flow rate: 2.1 L / min) supplied from an air supply unit (not shown) to flow into the measurement chamber 101. In addition, the apparatus 100 includes an inlet thermo-hygrometer 104 and an inlet flowmeter 105 provided in the inlet channel 102, an outlet thermo-hygrometer 106 and an outlet flowmeter 107 provided in the outlet channel 103, and a thermometer (thermistor) 108 provided in the measurement chamber 101. The thermometer 108 preferably has a temperature resolution of approximately 0.01°C.

[0072] The method for measuring the total amount of water vapor generated using the device 100 is as follows. First, the oxygen-shielding bag is opened for the heating device to be measured, which is sealed and housed in the oxygen-shielding bag, and one heating element is removed. If the heating element is housed in a bag, the heating element is removed together with the bag. The removed bag of the heating element is placed in the measurement chamber 101 with one side facing outward, and the thermometer 108 is placed on top of it. If one side of the bag and the other side are made of sheet materials with different breathability, the bag is placed in the measurement chamber 101 with the side of the sheet material with higher breathability facing outward, and the thermometer 108 is placed on that side. In this state, dehumidified air is flowed from the bottom of the measurement chamber 101 through the inlet channel 102, and the difference in absolute humidity before and after the air flow in the measurement chamber 101 is determined from the temperatures and humidities measured by the inlet thermo-hygrometer 104 and outlet thermo-hygrometer 106. Furthermore, the amount of water vapor released from the heating tool is calculated from the air flow rate measured by the inlet flow meter 105 and outlet flow meter 107. The total amount of water vapor is calculated as the total amount (mg / 10 min) measured over 10 minutes from the start of measurement, which is the time when the heating tool is removed from the oxygen-shielding bag and the heating element is brought into contact with air.

[0073] The shape of the ear hooks 4 in the heating device 1 is not limited to the sheet-like material shown in Figures 1 and 2, as long as it is possible to fix the main body 2 to both eyes of the user. For example, as shown in Figure 6, ear hooks 4 made of a string-like material or thread- or band-like material may be used. From the perspective of improving the fit of the heating device, it is preferable to use an elastic material such as rubber to make the ear hooks 4 stretchable.

[0074] The heating element 3 in the heating device 1 described above has been described as having two heating elements 3 held at a distance from each other, but the shape of the heating device is not particularly limited as long as it can provide a warming sensation to the user's eyes and the areas surrounding them. For example, one heating element having a shape and size that can cover the user's eyes and the areas surrounding them may be held between the top sheet 5 and the back sheet 6, or three or more heating elements may be held between the top sheet 5 and the back sheet 6.

[0075] 2 and 3, only a portion of the heating element 3 is fixed in the central region in the lateral direction X of the heating device 1, but this is not limited to this configuration. For example, the heating element 3 and the back sheet 6 may be bonded continuously or intermittently with an adhesive in the central region and regions other than the central region, or may be bonded by applying an adhesive to the entire surface of the back sheet 6 at the position where the heating element 3 is located.

[0076] The present disclosure also provides a packaging body for a heating device, which has a packaging bag and a heating device packaged in the packaging bag. The packaging bag is made of, for example, an oxygen-impermeable sheet material, and examples of such sheet material include a resin film alone or a resin film laminated with a thin metal film such as aluminum, which can improve light blocking and airtightness when the heating device is packaged.

[0077] When the heating implement is in the form of a package, the heating implement 1 is preferably contained in a packaging bag with a predetermined pressure applied thereto. In detail, the pressure applied to the heating device in the package is preferably 500 Pa or more, more preferably 1000 Pa or more, and even more preferably 2000 Pa or more, from the viewpoint of saving space in the package during storage and distribution. From the viewpoint of easily restoring the bulkiness of the sheet laminate after the packaging bag is opened, the pressure is preferably 5000 Pa or less, more preferably 4000 Pa or less, and even more preferably 3000 Pa or less.

[0078] The above-mentioned heating implement can be manufactured, for example, by the following method: The manufacturing method of the heating implement includes the step of manufacturing a topsheet. One embodiment of the process for producing the topsheet is a method in which a fibrous web containing any fibers is subjected to a step of blowing hot air onto the fibrous web to form the fibrous web into a nonwoven fabric. This step is known as air-through processing.

[0079] In a preferred embodiment of the topsheet, when manufacturing a topsheet having a two-layer structure consisting of a first fiber layer 51 containing first fibers and a second fiber layer 52 containing second fibers, the following method can be used, for example. First, a fiber web (hereinafter also referred to as the "first fiber web") composed solely of the first fibers or a mixture of the first fibers and the third fibers is laminated with a fiber web (hereinafter also referred to as the "second fiber web") composed solely of the second fibers to obtain a laminate. Then, hot air is blown onto this laminate to perform an air-through process, thereby obtaining the desired topsheet. This topsheet is classified as a so-called air-through nonwoven fabric, and is a breathable fiber sheet. Furthermore, the topsheet thus produced is generally in the form of a long strip, but may be cut to a predetermined size as needed.

[0080] As in the preferred embodiment described above, when heat is applied by air-through processing or the like during the manufacturing process of the topsheet, if the topsheet contains second or third fibers, the fibers, including the first fibers containing PET resin, are thermally fused together, which is advantageous in that it reduces fiber fuzzing in the resulting sheet. Furthermore, because many fusion points are formed between the fibers that make up the topsheet, even when the topsheet is transported to the subsequent manufacturing process of the heating device, the generation of paper dust is reduced, preventing the sheet surface from becoming rough and allowing for the production of heating devices with a good feel with high productivity. In addition, it reduces the amount of sheets discarded that no longer meet the required quality due to paper dust, thereby reducing the environmental impact.

[0081] Each of the above-mentioned fiber webs can be produced by a known web forming method such as a carding method. When the fibrous layer is a single layer (single layer structure), the above-mentioned method can be carried out using only the first fibrous web. When the fibrous layer is three or more layers, other fibrous webs made of other fibers can be laminated in addition to the first and second fibrous webs to form a laminate, and hot air can be blown onto this laminate. Alternatively, the topsheet can be obtained by needle-punching a fiber web or a laminate thereof, in which case the topsheet obtained is classified as a needle-punched nonwoven fabric, and is a breathable fiber sheet.

[0082] The topsheet thus produced is transported to be subjected to subsequent processes, and undergoes predetermined processing steps to produce the heating implement. For example, a method for manufacturing a heating device involves first conveying the top sheet and back sheet in the same direction, while applying adhesive to one side of at least one of the top sheet or back sheet. The adhesive may be applied continuously or intermittently in the sheet conveyance direction, or continuously or intermittently in a direction perpendicular to the conveyance direction. Additionally, the adhesive may be applied so as to leave areas where the adhesive is not applied. Next, the heating element 3 manufactured in a separate process is laminated on the adhesive-coated surface of the sheet to which the adhesive has been applied. After that, another sheet is further laminated on the heating element 3, and the two sheets 5, 6 are bonded together via the adhesive. Through this process, the main body 2 is formed, in which the top sheet 5 and the back sheet 6 are bonded together with the heating element 3 held between them. When bonding the two sheets 5, 6, for example, the bondability may be improved by introducing the laminate including the first sheet 5, heating element 3, and second sheet 6 between a pair of press rolls and pressing them.

[0083] Although the present invention has been described above based on the preferred embodiments, the present invention is not limited to the above embodiments.

[0084] In relation to the above-described embodiment of the present invention, the following heating device is further disclosed.

[0085] <1> The device comprises a top sheet positioned closer to the user's skin, a back sheet positioned farther from the user's skin, and a heating element held between the top sheet and the back sheet, the heating element contains an oxidizable metal, a carbon material, an electrolyte, and water; The heating element is configured to generate steam from the heating element itself as it generates heat, the top sheet is made of a breathable fiber sheet including fibers containing at least polyethylene terephthalate resin, The heating device wherein the topsheet comprises first fibers having a fiber diameter of more than 15 μm when measured by scanning electron microscope observation in a plan view.

[0086] <2> The fiber diameter of the first fibers is more preferably 20 μm or more, even more preferably 25 μm or more, and is preferably 60 μm or less, more preferably 50 μm or less, even more preferably 45 μm or less, even more preferably 40 μm, and even more preferably 30 μm or less. <1> The heating device described in <3> The first fibers are more preferably fibers made only of polyethylene terephthalate resin, or fibers made only of polyethylene terephthalate resin and a thermoplastic resin other than polyethylene terephthalate resin, More preferably, the fiber is made of polyethylene terephthalate resin alone. <1> or <2> The heating device described in

[0087] <4> The first fibers are core-sheath fibers having a core made of polyethylene terephthalate resin and a sheath made of polyethylene resin. <1> ~ <3> 10. The heating device according to claim 9, wherein <5> the topsheet has a multilayer structure including a first fiber layer and a second fiber layer, The first fibers are contained in only one of the fiber layers, The fiber layer not including the first fibers contains fibers having a different fiber diameter from the first fibers. <1> ~ <4> 10. The heating device according to claim 9, wherein <6> The top sheet has a two-layer structure having only a first fiber layer and a second fiber layer. <5> The heating device described in

[0088] <7> the first fiber layer includes the first fibers; the second fiber layer includes second fibers having a fiber diameter smaller than that of the first fibers and having a fiber diameter of 6 μm or more and 30 μm or less; <5> or <6> The heating device described in <8> The fiber diameter of the second fibers is smaller than the fiber diameter of the first fibers, and The thickness is more preferably 10 μm or more, even more preferably 13 μm or more, and more preferably 25 μm or less, even more preferably 20 μm or less, and particularly preferably 17 μm or less. <7> The heating device described in <9> The second fibers preferably contain a polyethylene resin, more preferably contain a polyethylene resin and a polyethylene terephthalate resin or a polypropylene resin, and further preferably consist of only a polyethylene resin and a polyethylene terephthalate resin or a polypropylene resin, and The fiber diameter of the second fibers is 6 μm or more and 30 μm or less. <7> or <8> The heating device described in <10> The second fibers are core-sheath fibers having a core made of polyethylene terephthalate resin or polypropylene resin and a sheath made of polyethylene resin. <7> ~ <9> 10. The heating device according to claim 9, wherein

[0089] <11> the first fiber layer is disposed on a surface farther from the user's skin during use; The second fiber layer is disposed on the skin contact surface during use. <5> ~ <10> 10. The heating device according to claim 9, wherein <12> the first fiber layer further includes third fibers having a fiber diameter smaller than that of the first fibers and larger than that of the second fibers; <5> ~ <11> 10. The heating device according to claim 9, wherein <13> The fiber diameter of the third fibers is preferably 15 μm or more, more preferably 18 μm or more, even more preferably 20 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, and even more preferably 24 μm or less, provided that the fiber diameter of the third fibers is smaller than the fiber diameter of the first fibers and larger than the fiber diameter of the second fibers. <12> The heating device described in

[0090] <14> The third fibers preferably contain a thermoplastic resin other than polyethylene terephthalate resin, more preferably contain polyethylene resin, further preferably contain polyethylene resin and PET resin or PP resin, and further preferably consist of only PP resin and PE resin, and The fiber diameter is smaller than the fiber diameter of the first fibers and larger than the fiber diameter of the second fibers, <12> or <13> The heating device described in <15> The third fiber is a core-sheath fiber having a core made of polyethylene terephthalate resin or polypropylene resin and a sheath made of polyethylene resin. <12> ~ <14> 10. The heating device according to claim 9, wherein <16> the second fibrous layer includes second fibers; The second fibers and the third fibers contain resins whose components are different from each other. <12> ~ <15> 10. The heating device according to claim 9, wherein <17> the first fibers are fibers made only of polyethylene terephthalate resin and a thermoplastic resin other than polyethylene terephthalate resin, The third fiber is a fiber containing a thermoplastic resin other than polyethylene terephthalate resin. <12> ~ <16> 10. The heating device according to claim 9, wherein

[0091] <18> The mass ratio of the third fibers to the total mass of the first fiber layer is preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 40% by mass or more, and is preferably 90% by mass or less, more preferably 75% by mass or less, even more preferably 60% by mass or less. <12> ~ <17> 10. The heating device according to claim 9, wherein <19> The mass ratio of the first fibers to the total mass of the first fiber layer is preferably 10% by mass or more, more preferably 25% by mass or more, even more preferably 40% by mass or more, and is preferably 90% by mass or less, more preferably 75% by mass or less, even more preferably 60% by mass or less. <12> ~ <18> 10. The heating device according to claim 9, wherein <20> The first fiber layer includes first fibers including polyethylene terephthalate resin and polyethylene resin. <5> ~ <19> 10. The heating device according to claim 9, wherein <21> the second fibrous layer includes second fibers; The content of the second fibers in the second fiber layer is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and even more preferably 100% by mass. <5> ~ <20> 10. The heating device according to claim 9, wherein

[0092] <22> The density of the fibers in the first fiber layer is preferably 1500 fibers / cm 2 Less than 1000 fibers / cm, preferably 1000 fibers / cm 2 More preferably, 700 fibers / cm or less 2 less than 150 lines / cm 2 The above <5> ~ <21> 10. The heating device according to claim 9, wherein <23> The fiber density of the second fiber layer is 200 fibers / cm 2 Over 1500 pieces / cm 2 The above-mentioned <5> ~ <22> 10. The heating device according to claim 9, wherein <24> The density of the fibers in the second fiber layer is preferably 300 fibers / cm 2 More preferably, 400 fibers / cm 2 or more, and preferably 1200 fibers / cm 2 Less than 1000 fibers / cm, preferably 1000 fibers / cm 2 The above-mentioned <5> ~ <23> 10. The heating device according to claim 9, wherein

[0093] <25> the first fiber layer is composed only of first fibers and third fibers having a fiber diameter smaller than that of the first fibers, excluding other fibers that are inevitably mixed in; the second fiber layer is made only of second fibers having a fiber diameter smaller than that of the first fibers and having a fiber diameter of 6 μm or more and 30 μm or less, excluding other fibers that are inevitably mixed in; The fiber diameter of the third fibers is larger than the fiber diameter of the second fibers. <5> ~ <24> 10. The heating device according to claim 9, wherein <26> The basis weight of the first fiber layer is 10 g / m 2 It is preferable that the content is 15 g / m or more. 2 More preferably, it is 20 g / m or more.2 More preferably, 100g / m 2 Preferably, it is 80 g / m or less. 2 More preferably, it is 60 g / m or less. 2 It is more preferable that the following is true: <5> ~ <25> 10. The heating device according to claim 9, wherein <27> The basis weight of the second fiber layer is 5 g / m 2 It is preferable that the content is 10 g / m or more. 2 More preferably, it is 15 g / m or more. 2 More preferably, 50g / m 2 Preferably, it is 40 g / m or less. 2 More preferably, it is 30 g / m or less. 2 It is more preferable that the following is true: <5> ~ <26> 10. The heating device according to claim 9, wherein

[0094] <28> The top sheet is a fiber sheet in which the sheet shape is maintained by at least one of fusion and entanglement of constituent fibers, The constituent fibers have contact portions where they are in contact with each other. <1> ~ <27> 10. The heating device according to claim 9, wherein <29> The fiber sheet is an air-through nonwoven fabric or a needle-punched nonwoven fabric. <28> The heating device described in <30> The thickness of the surface sheet at the start of heat generation of the heating device is 1.8 mm or more and 6.0 mm or less. <1> ~ <29> 10. The heating device according to claim 9, wherein <31> The heating element includes a layer containing an oxidizable metal, a carbon material, an electrolyte, and water, and a water retention agent layer containing a water-absorbent polymer disposed adjacent to the layer. <1> ~ <30> 10. The heating device according to claim 9, wherein <32> The aforementioned <2> ~ <27> A method for producing a heating implement according to any one of the above, The manufacturing method includes a step of manufacturing a topsheet, In the above step, a laminate obtained by laminating a web of fibers containing polyethylene terephthalate resin and a web containing fibers other than said fibers is subjected to an air-through treatment. [Example]

[0095] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples. The fiber diameter and fiber count were determined by SEM observation of the sample topsheet in plan view, with the fibers magnified 2000 times. The SEM observation position was then changed and repeated until the number of fibers reached 100 or more to confirm the number of layers in the topsheet. This observation was performed using image analysis software (Photoshop, Adobe Inc.) to color-code the fibers and measure their lengths. The fiber diameter range was then selected from 0.1 to 0.5 μm. Based on the measurement results, a histogram of the fiber count frequency and fiber diameter distribution was created, and the number of peaks determined whether the topsheet contained a single type of fiber or multiple types. The fiber type and mass fraction of the fiber in each fiber layer were calculated from the number of layers and the fiber diameter of each layer in each example and comparative example. Unless otherwise specified, "%" in the following description means "% by mass."

[0096] Example 1 A first fiber web (basis weight: 40 g / m) containing 100% first fibers by mass, the first fibers being core-sheath fibers whose core is made of PET resin and whose sheath is made of PE resin (50% by mass of each resin). 2 ) and a second fiber web containing 100% by mass of second fibers, which are core-sheath fibers having a core made of PET resin and a sheath made of PE resin (50% by mass of each resin), to form a laminate. This laminate was subjected to an air-through treatment to form a topsheet 5 (air-through nonwoven fabric, basis weight: 60 g / m) having a two-layer structure of a first fiber layer 51 and a second fiber layer 52. 2 ) was obtained. The back sheet 6 is an air-through nonwoven fabric (basis weight: 30 g / m) made of fibers containing only thermoplastic resin manufactured by Kinsei Paper Co., Ltd. 2) was used in a single layer. Number of surface sheet layers: 2 First fiber layer: 100% fiber with a fiber diameter of 22 μm Second fiber layer: 100% fiber with a fiber diameter of 15 μm

[0097] Separately, a heat generating element 3 that generates steam when heated was manufactured. First, iron powder was added as an oxidizable metal to an aqueous solution of salt as an electrolyte and a thickener dissolved in water, and the mixture was stirred. Activated carbon was then added as a carbon material and the mixture was stirred thoroughly until it was uniformly dispersed, to obtain a paste-like heat generating composition. The heat-generating paste composition was applied to polyethylene-laminated tissue paper with a basis weight of 600 g / m. 2 Next, particles of a water-absorbing polymer (AQUALIC (registered trademark) CA, manufactured by Nippon Shokubai Co., Ltd.) were applied as a water-retaining material onto the heat-generating composition at a basis weight of 70 g / m. 2 Then, a crepe paper (basis weight 65 g / m) was placed on the water-absorbent polymer layer. 2 ) were laminated to obtain a heat generating part 3a equipped with a water-retaining material layer. The heat generating part 3a was then cut to a size of 50 mm x 50 mm. Separately, a moisture-permeable sheet cut to 63 mm x 63 mm and a moisture-impermeable sheet were placed between the heat generating element, and the four sides of these sheets were heat-sealed to obtain a heat generating element 3 in which the heat generating part 3a was housed within a bag 3b.

[0098] The topsheet 5 was arranged so that the first fiber layer 51 constituted the surface facing the heating element 3 and the second fiber layer 52 constituted the surface contacting the heated object. The moisture-permeable sheet in the bag body 3b was arranged so as to face the topsheet 5. By arranging each component in this manner and joining them so as to accommodate the heating element 3, which is designed to generate steam upon heat generation, between the above-mentioned sheets 5 and 6, a heating device having the structure shown in Figures 1 to 3 and Figure 5 was obtained.

[0099] Examples 2 to 4 As shown in Table 1 below, the types and composition ratios of the fibers constituting the topsheet 5 were changed. Specifically, a mixture of first fibers made only of PET resin and third fibers with a core of PP resin and a sheath of PE resin (Example 2) or a core of PET resin and a sheath of PE resin (Examples 3 and 4) was fed into a carding machine to form a mixed fiber web of the first fibers and third fibers, which was designated as the first fiber web. Other than this, a heating device equipped with a topsheet 5 that was a two-layered air-through nonwoven fabric was obtained in the same manner as in Example 1. <Example 2> Number of surface sheet layers: 2 First fiber layer: 30% fibers with a fiber diameter of 27 μm, 70% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm. Example 3 Number of surface sheet layers: 2 First fiber layer: 30% fibers with a fiber diameter of 27 μm, 70% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm. Example 4 Number of surface sheet layers: 2 First fiber layer: 50% fibers with a fiber diameter of 27 μm, 50% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm.

[0100] Example 5 As shown in Table 1 below, the types and composition ratios of the fibers constituting the topsheet 5 were changed. Specifically, a heating device equipped with a topsheet 5 that was a two-layer air-through nonwoven fabric was obtained in the same manner as in Example 1, except that a second fiber web was used that was 100% by mass of second fibers, which were core-sheath fibers with a core made of PP resin and a sheath made of PE resin (50% by mass of each resin). Number of surface sheet layers: 2 First fiber layer: 50% fibers with a fiber diameter of 27 μm, 50% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm.

[0101] Example 6 As shown in Table 1 below, the types and composition ratios of the fibers constituting the topsheet 5 were changed. Specifically, a mixture of first fibers having a core of PET resin and a sheath of PE resin and third fibers having a core of PP resin and a sheath of PE resin was fed into a carding machine to form a mixed fiber web of the first fibers and third fibers, which was designated as the first fiber web. Other than this, a heating device equipped with a topsheet 5 that was a two-layer air-through nonwoven fabric was obtained in the same manner as in Example 1. Example 6 Number of surface sheet layers: 2 First fiber layer: 50% fibers with a fiber diameter of 27 μm, 50% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm.

[0102] Example 7 As shown in Table 1 below, the heating device was obtained in the same manner as in Example 1, except that the type and composition ratio of the fibers constituting the surface sheet 5 were changed, core-sheath fibers of PET resin / PE resin having a fiber diameter different from that of Example 5 were used as the first fibers, and a single-layer air-through nonwoven fabric consisting only of the first fibers was used as the surface sheet 5. Example 7 Number of surface sheet layers: 1 First fiber layer: 100% fiber with a fiber diameter of 22 μm.

[0103] Example 8 As shown in Table 1 below, the first fiber (basis weight: 20 g / m) was a core-sheath fiber (50% by mass of each resin) in which the core was made of PET resin and the sheath was made of PE resin. 2 ) and a third fiber (basis weight: 20 g / m) with a core made of PP resin and a sheath made of PE resin. 2 ) to form a first fiber web (total basis weight: 40 g / m 2 The first fibers used in this example had a fiber diameter different from that used in Example 1. Separately, a second fiber web (basis weight: 20 g / m) containing 100% second fiber by mass was prepared, the second fiber being a core-sheath fiber with a core made of PP resin and a sheath made of PE resin (50% by mass of each resin). 2 ) was used. Heating devices having a surface sheet 5 that was a two-layered air-through nonwoven fabric were obtained in the same manner as in Example 1, except that these fiber webs were used. Example 8 Number of surface sheet layers: 2 First fiber layer: 50% fibers with a fiber diameter of 40 μm, 50% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm.

[0104] Example 9 As shown in Table 1 below, the type and composition ratio of the fibers constituting the topsheet 5 were changed, and a first fiber web consisting only of first fibers, which are core-sheath fibers made only of PET resin, was needle-punched to obtain a single-layer topsheet 5 as a needle-punched nonwoven fabric. Other than this, the heating device was obtained in the same manner as in Example 1. Example 9 Number of surface sheet layers: 1 First fiber layer: 100% fiber with a fiber diameter of 19 μm.

[0105] Example 10 As shown in Table 1 below, the types and composition ratios of the fibers constituting the topsheet 5 were changed. Specifically, a mixture of first fibers made only of PET resin and third fibers with a PP resin core and a PE resin sheath was fed into a carding machine to form a mixed fiber web of the first fibers and third fibers, which was designated the first fiber web. Other than this, a heating device equipped with a topsheet 5 that was a two-layer air-through nonwoven fabric was obtained in the same manner as in Example 1. Example 10 Number of surface sheet layers: 2 First fiber layer: 60% fibers with a fiber diameter of 27 μm, 40% fibers with a fiber diameter of 22 μm. Second fiber layer: 100% fiber with a fiber diameter of 15 μm.

[0106] Comparative Example 1 As shown in Table 1 below, a fiber web was produced from a mixture of first fibers, which were core-sheath fibers with a core of PP resin and a sheath of PE resin, and third fibers consisting only of PP resin, and this fiber web was needle-punched to obtain a single-layer surface sheet 5 as a needle-punched nonwoven fabric. Other than this, the heating device was obtained in the same manner as in Example 1. <Comparative Example 1> Number of surface sheet layers: 1 First fiber layer: 30% fibers with a fiber diameter of 22 μm, 70% fibers with a fiber diameter of 12 μm.

[0107] [Measurement of sheet thickness and thickness increase] For each of the heating devices of the Examples and Comparative Examples, the thickness T1 (mm) of the topsheet 5 at the start of heat generation and the thickness T2 (mm) of the sheet 10 minutes after the start of heat generation were measured and calculated. The measurement environment was an indoor environment with a temperature of 26°C and a relative humidity of 50%.

[0108] Specifically, the heating devices of each Example and Comparative Example were sealed in a packaging bag, and then the packaging bag was opened to expose the heating devices to an oxygen-containing atmosphere such as air. The surface sheet 5 alone was carefully cut out from the heating device to a 1.5 cm square without compressing the sheet in the thickness direction. This measurement sample was placed on the flat surface of a digital microscope (VHX-1000, manufactured by KEYENCE Corporation) with the cross section of the sheet facing upward at a 90-degree angle. This operation was performed within 30 seconds after the opening of the packaging bag. 30 seconds after the opening, the length from end to end of the sheet cross section was measured at three or more locations using the digital microscope, and the average value was taken as the sheet thickness T1 (mm) at the start of fever. Using the same method, the surface sheet 5 was carefully cut out from the heating device after 10 minutes, without compressing the sheet, to the above dimensions. This was taken as the sheet thickness T2 (mm) 10 minutes after the start of fever. The smaller the change in thickness (T2-T1), the higher the bulk recovery of the topsheet 5 immediately after use, and the better the fit and feel of the heating device 1. The results are shown in Table 1 below.

[0109] [Sensory evaluation] For each example and comparative example, a specialist panel evaluated the smooth feel of the surface sheet when touched, during and after use, the flexibility of the surface sheet, and the fit when the heating device was worn over both eyes for 20 minutes, using the following criteria. The arithmetic mean scores of the specialist panelists for each evaluation are shown in Table 1 as the evaluation results. The higher the score for each evaluation result, the smoother, more flexible, and more fit the heating device has when it comes into contact with the skin.

[0110] <Evaluation criteria for surface sheet smoothness> 4 points: The texture is very smooth before use, and remains smooth even after use, with no noticeable fuzzing of the fibers even after use. 3 points: The texture is smooth before use and remains smooth during use, but some fuzziness of the fibers is observed after use. 2 points: The texture is smooth before use, but the fibers become fuzzy during and after use, making the texture less smooth. 1 point: Fuzziness of the fibers was perceived before, during and after use, and smoothness was very poor.

[0111] <Evaluation criteria for surface sheet flexibility> 5 points: The surface sheet is very soft, adheres firmly from immediately after use until the end of use, and has excellent flexibility and feel. 4 points: The surface sheet is soft, adheres tightly from immediately after use until the end of use, and has good flexibility and feel. 3 points: The surface sheet has a moderate rigidity, adheres tightly enough to feel warm during use, and feels comfortable. 2 points: The surface sheet is a little hard and has poor rigidity, but adheres well when in use. 1 point: The surface sheet is very hard and has poor rigidity, resulting in poor adhesion during use.

[0112] <Fit evaluation criteria> 5 points: The heating device adheres firmly to the eye area and surrounding areas while in use, providing an excellent fit until the end of use. 4 points: The heating device adheres to the eye area while in use and maintains a good fit until the end of use. 3 points: The heating device is held in place around the eyes and in the vicinity while in use, and fits snugly until the end of use. 2 points: While wearing the heating device, it does not adhere well to the eyes, and the fit is poor until the end of use. 1 point: While wearing the heating device, there was no adhesion between the heating device and the eyes, and the fit was very poor until the end of use.

[0113] [Productivity evaluation using paper dust] For the heating devices 1 of the examples and comparative examples, the amount of paper dust discarded when produced using an actual machine was visually judged by expert panelists. The higher the score of the evaluation results, the more productive the heating device is. <Productivity> 3. No paper dust is generated during production, no raw materials are wasted, a good manufacturing environment can be maintained, and there is no impact on the heating device. 2 points: Although a small amount of paper dust is generated during production, the manufacturing environment is such that the amount of raw material discarded is not a problem, and it does not affect the heating device. 1 point: Paper dust is generated during production and the manufacturing environment results in a large amount of raw material being discarded, but this does not affect the heating implement.

[0114] [Evaluation of 38°C duration and maximum temperature reached] The heating devices of the Examples and Comparative Examples were measured for 38°C duration and maximum temperature achieved using the following method. The longer the 38°C duration, the better the heat retention, and the higher the maximum temperature achieved, the better the heat generation characteristics. The results are shown in Table 1 below.

[0115] First, in an environment with a room temperature of 20°C and a humidity of 50%RH, the oxygen-shielding bag containing the heating device to be measured is opened, and one heating element is removed from the heating device while still contained in the bag. Separately, the temperature sensor of a data collection thermometer (LT-8, manufactured by Gram) is attached to the wearer's upper eyelid and fixed with surgical tape.Then, the heating device is worn so that the top sheet 5 is in contact with the temperature sensor. Then, with the thermometer connected to the temperature sensor, the temperature is measured over time. Measurements are started at the start of heat generation and are taken every 10 seconds, for a total of 60 minutes. The heat generation profile was plotted with the measured temperature (°C) on the vertical axis and the measurement time (seconds) on the horizontal axis, and the length of time during which a temperature of 38°C or higher was measured was defined as the 38°C or higher holding time. The maximum temperature measured from the same temperature profile was defined as the maximum reached temperature.

[0116] [Evaluation of water vapor generation amount] The total amount of water vapor over 10 minutes was measured for the heating devices of the Examples and Comparative Examples using the method described above. The higher the total amount of water vapor over 10 minutes, the better the heating characteristics and the higher the amount of water vapor generated, indicating that the heating device can provide a comfortable sensation of warmth and moisture to the heated object. The results are shown in Table 1 below.

[0117] [Table 1]

[0118] As shown in Table 1, the heating devices of each Example, which used fibers containing PET resin as the constituent fibers of the topsheet, showed that the bulk of the topsheet recovered quickly immediately after use, was flexible, felt good to the touch, and provided a good fit when in use, compared to the heating devices of the Comparative Examples. In particular, the use of a heating element configured to generate 10 mg / 10 min or more of water vapor is advantageous because it can provide good heat. Therefore, it can be seen that the heating device of the present disclosure has good bulk recovery after opening, and is excellent in both flexibility and fit to the wearer's body immediately after use.

[0119] The heating device of Example 8, a preferred embodiment of the present disclosure, has an excellent surface sheet smoothness and flexibility, and a good fit of the heating device at the same level as those of Examples 4 and 5, while generating less paper dust. This is because the first fibers used in Example 8 contain PE resin, which has a lower melting point than PET resin, and the PE resin melts due to heat from the air-through process, etc., forming more fusion points between the constituent fibers. This is thought to be because the shedding and peeling of the constituent fibers, including the first fibers, is effectively reduced. Furthermore, reducing the generation of paper dust prevents deterioration in the quality of raw materials due to the generation and adhesion of paper dust during the manufacturing of heating devices, thereby reducing the amount of unintentional waste of raw materials that do not meet the required quality during manufacturing. As a result, the heating device of the present invention is designed to reduce manufacturing costs and improve productivity during its manufacture, and is advantageous in that it can achieve a reduction in the environmental burden due to reduced waste. In addition, it is advantageous in that it can reduce contamination of the manufacturing equipment and manufacturing environment due to the generation and adhesion of paper dust, as well as the labor and costs required for maintenance and cleaning that accompany this. Furthermore, the heating device of Example 10, which is the most preferred embodiment of the present disclosure, has an excellent surface sheet flexibility at the same level as that of Example 8, while being particularly excellent in terms of the smoothness of the surface sheet, the fit of the heating device, and productivity in terms of paper dust generation. The reason for this is thought to be that, while the first fibers used in Example 8 contain PET resin and PE resin, the first fibers used in Example 10 contain only PET resin, so that when the compressed state of the heating device is released, the bulk of the surface sheet easily recovers and the preferred thickness is sufficiently maintained. [Industrial Applicability]

[0120] According to the present invention, a heating implement is provided that has good bulk recovery after opening, and provides a good fit and a comfortable feel immediately after use.

Claims

1. The device comprises a top sheet positioned closer to the user's skin, a back sheet positioned farther from the user's skin, and a heating element held between the top sheet and the back sheet, the heating element contains an oxidizable metal, a carbon material, an electrolyte, and water; The heating element is configured to generate steam from the heating element itself as it generates heat, the top sheet is made of a breathable fiber sheet including fibers containing at least polyethylene terephthalate resin, The heating device, wherein the topsheet comprises first fibers having a fiber diameter of more than 15 μm when measured by scanning electron microscope observation in a plan view.

2. the topsheet has a multi-layer structure including a first fiber layer and a second fiber layer, the first fibers are contained in only one of the fiber layers, 2. The heating implement according to claim 1, wherein fibers having a diameter different from that of the first fibers are contained in a fiber layer that does not contain the first fibers.

3. the first fiber layer includes the first fibers; 3. The heating implement according to claim 2, wherein the second fiber layer includes second fibers having a fiber diameter smaller than that of the first fibers and having a fiber diameter of 6 μm or more and 30 μm or less.

4. the first fiber layer is disposed on a surface farther from the user's skin during use; 4. The heating implement according to claim 2 or 3, wherein the second fiber layer is disposed on the surface that comes into contact with the skin during use.

5. The heating implement according to any one of claims 2 to 4, wherein the first fiber layer further comprises third fibers having a fiber diameter smaller than that of the first fibers and larger than that of the second fibers.

6. The heating device according to any one of claims 2 to 5, wherein the first fiber layer comprises first fibers containing polyethylene terephthalate resin and polyethylene resin.

7. The heating device according to any one of claims 2 to 6, wherein the first fibers contain polyethylene terephthalate resin and have a fiber diameter of more than 15 μm and not more than 60 μm.

8. The heating implement according to any one of claims 2 to 7, wherein the second fibers contain polyethylene resin and have a fiber diameter of 6 μm or more and 30 μm or less.

9. The heating device according to any one of claims 2 to 8, wherein the third fibers contain a thermoplastic resin other than polyethylene phthalate resin, and the fiber diameter is smaller than the fiber diameter of the first fibers and larger than the fiber diameter of the second fibers.

10. The fiber density of the second fiber layer is 200 fibers / cm ２ Over 1500 strands / cm ２ The heating device according to any one of claims 2 to 9, wherein:

11. The top sheet is a fiber sheet in which the sheet shape is maintained by at least one of fusion and entanglement of constituent fibers, The heating implement according to any one of claims 1 to 10, wherein the constituent fibers have contact portions where they come into contact with each other.

12. The heating implement according to any one of claims 1 to 11, wherein the thickness of the surface sheet at the start of heat generation of the heating implement is 1.8 mm or more and 6.0 mm or less.

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