Absorbent article, method of manufacturing same, and moisture detection system including same

Abstract

To provide an absorbent article that can appropriately detect water generation with a simple configuration and provides little discomfort for a wearer.SOLUTION: An absorbent article includes at least a top sheet, an absorber, a back sheet, and a sensor having a water detection unit. The absorber is composed of a core for absorbing water and a wrap sheet wrapping the core. The sensor is disposed between the wrap sheet of the absorber and the back sheet. The sensor's thickness is equal to or smaller than 1 mm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an absorbent article, a method for manufacturing the same, and a moisture sensing system including the same. [Background technology]

[0002] Conventionally, systems using RFID (Radio Frequency Identification) have been known as technologies for detecting the presence of moisture in absorbent articles. In particular, for nursing care applications, a technology is known in which a wireless communication device such as an IC tag is embedded in a diaper to detect moisture generated due to urination or the like of a care recipient.

[0003] For example, Non-Patent Document 1 discloses a technology in which a reader transmits a radio wave signal with a frequency of 950 MHz (UHF band) to an IC tag and detects moisture using the reflected signal. This technology detects the occurrence of moisture by utilizing the change in the reflection coefficient when the antenna gets wet.

[0004] Furthermore, Patent Document 1 discloses a technology in which an IC tag equipped with a wetness detection terminal is attached to a diaper, and the presence or absence of moisture is detected according to fluctuations in the voltage value of the wetness detection terminal. With this technology, when the wetness detection terminal detects wetness, the IC tag emits a signal different from that in a dry state, or does not emit a signal at all, so a reader that communicates with the IC tag detects the wetness state of the IC tag according to the type of signal received or the presence or absence of a signal.

[0005] Furthermore, Patent Document 2 discloses a structure for a diaper that detects urination using an attached sensor device, which includes a guide portion for attaching the sensor device to the crotch portion of the diaper in order to accurately detect urination while reducing discomfort to the wearer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-349418 [Patent Document 2] Japanese Patent Application Publication No. 2019-130244 [Non-patent literature]

[0007] [Non-Patent Document 1] Hiromasa Nakajima and three others, "Development of a Urination Detection System Using RFID Technology," IEICE Transactions on Electronics, Information and Communication Engineers, Vol. J96-B, No. 12, pp. 1378-1385, December 1, 2013. Summary of the Invention [Problem to be solved by the invention]

[0008] However, with the technology described in Non-Patent Document 1, radio waves are absorbed as moisture is generated, and the antenna impedance changes significantly, causing the receiving sensitivity of the IC tag to drop significantly and making it impossible to communicate with the reader, which means that the reader cannot determine whether the IC tag has malfunctioned.

[0009] Furthermore, the technology described in Patent Document 1 changes the state or function of the IC chip depending on the detection result of the wetness detection terminal, but this requires a relatively expensive IC chip and technology to mount the IC chip with high precision, which poses many cost issues. Furthermore, mounting an IC chip also poses the issue of weak mechanical strength as an IC tag.

[0010] Furthermore, in the technology described in Patent Document 2, although the sensor device is positioned at a predetermined position by providing a guide part, the thickness dimension of the sensor device is usually 1 to 30 mm, preferably 1 to 20 mm, and more preferably 1 to 15 mm, and the discomfort felt by the wearer is not sufficiently reduced.

[0011] The present invention has been made in view of the above, and aims to provide an absorbent article that can accurately detect the generation of moisture with a simple configuration and that causes little discomfort to the wearer. [Means for solving the problem]

[0012] In order to solve the above-mentioned problems and achieve the objectives, the absorbent article of the present invention is an absorbent article comprising at least a top sheet, an absorbent body, a back sheet, and a sensor having a moisture detection unit, wherein the absorbent body consists of a core that absorbs moisture and a wrap sheet that covers the core, and the sensor is disposed between the wrap sheet and the back sheet of the absorbent body, and the thickness of the sensor is 1 mm or less.

[0013] In the absorbent article according to the present invention, the moisture detector includes a conductor, and at least a portion of the conductor is in contact with the wrap sheet.

[0014] Furthermore, in the absorbent article according to the present invention, the moisture detecting part has a thickness of 200 μm or less.

[0015] Furthermore, in the absorbent article according to the present invention, the moisture detecting section includes a conductor, and the conductor has a thickness of 100 μm or less.

[0016] Further, in the absorbent article according to the present invention, in the above invention, the sensor is configured so that no part other than the moisture detection portion comes into contact with moisture.

[0017] Further, in the absorbent article according to the present invention, the sensor has an antenna portion.

[0018] In addition, in the absorbent article according to the present invention, in the above invention, at least a part of the antenna section is arranged in a portion where the top sheet and the back sheet face each other without sandwiching the absorbent body therebetween.

[0019] Further, in the absorbent article according to the present invention, in the above invention, the conductor of the moisture detecting portion comprises one or more pairs of opposing patterns that contain at least a metal element and an organic component and are not directly connected to each other.

[0020] Furthermore, in the absorbent article according to the present invention, in the above invention, the resistance between one or more pairs of opposing patterns of the moisture detecting section that are not directly connected to each other becomes 10 MΩ or less upon contact with moisture.

[0021] In the absorbent article according to the present invention, the sensor has a circuit portion.

[0022] Further, in the absorbent article according to the present invention, in the above invention, the sensor has a circuit section and an antenna section, and the conductive section of the circuit section and the antenna section are not in contact with each other.

[0023] In addition, in the absorbent article according to the present invention, the moisture detection section and the circuit section are formed on the same surface of the same substrate.

[0024] In the absorbent article according to the present invention, the circuit section includes a thin film transistor containing carbon nanotubes.

[0025] Furthermore, the absorbent article according to the present invention is manufactured using a method that uses printing technology in any of its manufacturing steps.

[0026] A moisture detection system according to the present invention includes an absorbent article according to any one of the above-described inventions, and a transceiver device having means for wirelessly communicating with the absorbent article. [Effects of the Invention]

[0027] According to the present invention, it is possible to provide an absorbent article that can accurately detect the generation of moisture with a simple configuration and that causes little discomfort to the wearer, and a moisture detection system using the same. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a plan view showing an absorbent article according to a first embodiment of the present invention. [Figure 2]FIG. 2 is a cross-sectional view showing the absorbent article according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a schematic diagram showing a moisture detection unit in a sensor in an absorbent article according to an embodiment of the present invention. [Figure 4] FIG. 4 is a plan view showing an absorbent article according to a modified example of the first embodiment of the present invention. [Figure 5] FIG. 5 is a schematic diagram showing a first modification of the sensor in the absorbent article according to the embodiment of the present invention. [Figure 6] FIG. 6 is a schematic diagram showing a second modification of the sensor according to the embodiment of the present invention. [Figure 7] FIG. 7 is a schematic cross-sectional view showing a thin film transistor according to an embodiment of the present invention. [Figure 8] FIG. 8 is a plan view showing an absorbent article according to a second modification of the first embodiment of the present invention. [Figure 9] FIG. 9 is a schematic diagram showing a third modification of the sensor according to the embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing a fourth modification of the sensor according to the embodiment of the present invention. [Figure 11] FIG. 11 is a schematic diagram showing a moisture detection system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, modes for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the accompanying drawings.

[0030] (Embodiment 1) FIG. 1 is a plan view schematically showing an absorbent article according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line XX' of FIG.

[0031] The absorbent article 10 according to the first embodiment includes a top sheet 12 on the human body side and a back sheet 11 on the clothing side, with an absorbent body 20 sandwiched between the top sheet 12 and the back sheet 11. The absorbent body 20 has a core 21 covered with a wrap sheet 22. A sensor 30 is disposed between the back sheet 11 and the wrap sheet 22 that covers the absorbent body 20.

[0032] The absorbent article 10 is not particularly limited in its use or shape, as long as it is an absorbent article designed and manufactured to absorb moisture excreted from the human body. Specific examples of the absorbent article 10 include disposable diapers, feminine hygiene products, and incontinence products. The absorbent article 10 may also be a moisture-absorbing pad. A pants-type diaper, reusable pants, or the like can be worn over such a pad.

[0033] The top sheet 12 is not particularly limited in terms of material or configuration, as long as it is permeable to moisture absorbed by the absorbent article 10. Specific examples of the top sheet 12 include liquid-permeable nonwoven fabrics, three-dimensional perforated films, and laminates thereof. It may also be a sheet made by combining various materials and having different properties in terms of moisture permeability or surface condition in parts. Because the top sheet 12 comes into direct contact with the human body, it is preferably made of a nonwoven fabric or the like that feels pleasant against the skin.

[0034] The backsheet 11 is not particularly limited in terms of material or configuration, as long as it is configured to prevent the permeation of moisture absorbed by the absorbent article 10. Specific examples of the backsheet 11 include nonwoven fabrics, non-porous films, porous films, and laminates thereof. It may also be a composite of various materials, resulting in a sheet that is partially moisture-impermeable or has different surface properties. While the backsheet 11 is configured to prevent moisture from passing through, it is desirable for it to be vapor-permeable to improve comfort for the wearer.

[0035] There are no particular limitations on the material or configuration of the core 21 as long as it is capable of absorbing and retaining moisture. Specific examples of the core 21 include absorbent materials made of cellulose fibers or water-absorbent polymers.

[0036] The wrap sheet 22 is not particularly limited in material or configuration as long as it is a moisture-permeable material and can hold the core 21. Specific examples of the wrap sheet 22 include paper, nonwoven fabric, perforated film, and laminates and composites thereof.

[0037] The top sheet 12, absorbent body 20 and back sheet 11 are bonded together to form the absorbent article 10, but the bonding method, materials used for bonding, bonding area, bonding range, etc. are not particularly limited, and any suitable method or configuration can be used for each as long as it can achieve the function of the absorbent article.

[0038] In the first embodiment, the top sheet 12 may have upright gathers near the long side edges to prevent moisture leakage. Also, the back sheet 11 may have tapes near the short side edges to form a pants-type diaper.

[0039] Furthermore, in order to improve the wearing comfort of the wearer, the outer shape of the absorbent article 10 according to the first embodiment may be shaped to fit the human body.

[0040] Furthermore, a nonwoven fabric or the like may be disposed on the side of the backsheet 11 opposite to the topsheet 12 (the side that comes into contact with clothing) to improve the feel.

[0041] Although not shown, the sensor 30 has a configuration in which a moisture detection unit is formed on a substrate, and the moisture detection unit detects moisture excreted from the human body. Moisture excreted from the human body passes through the top sheet 12 and is absorbed by the absorbent body 20. By arranging the sensor 30 between the absorbent body 20 and the back sheet 11, moisture absorbed by the absorbent body 20 comes into contact with the moisture detection unit of the sensor 30, making it possible to detect moisture excreted from the human body. Furthermore, because the sensor 30 is arranged on the back sheet 11 side of the absorbent body 20 rather than the top sheet 12 side, this reduces any discomfort felt by the wearer when wearing the absorbent article 10 and does not impair comfort when wearing the absorbent article 10.

[0042] The moisture detection unit is not particularly limited in its structure, materials constituting it, or method of detecting moisture, as long as it has the function of changing its state depending on the presence or absence of moisture and being able to detect the presence of moisture.Specific configurations of the moisture detection unit include, for example, (1) a configuration in which a pair of conductors are arranged with a certain spatial distance between them and moisture adheres between them to change the conductivity between the conductors, (2) a configuration in which a pattern of multiple independent conductors is arranged and moisture adheres between the conductors to detect a change in the conductivity between the conductors, (3) a configuration in which a pattern of multiple independent conductors is arranged and moisture adheres to a moisture-impermeable insulating material arranged on the conductors to change the capacitance between the conductors, and (4) a configuration in which a conductor pattern formed in a loop shape to obtain a specific inductance is included and the proximity of moisture to the conductor changes the capacitance value generated in the conductor, and so on.

[0043] The conductor is not particularly limited in material or composition as long as it has electrical conductivity, but it is preferable that it has low corrosion resistance due to moisture and high conductivity. Specific examples of the conductor include inorganic substances containing at least one element selected from the group consisting of gold, copper, silver, nickel, tin, bismuth, lead, zinc, palladium, platinum, aluminum, tungsten, molybdenum, and carbon, mixtures or laminates of the above inorganic substances and organic substances, and conductive organic substances.

[0044] A preferred shape of the moisture detector is shown in Fig. 3. The moisture detector 60 shown in the figure has a pattern of a first electrode 61 and a second electrode 62 on an electrically insulating substrate 63. These electrodes may be connected to an external power source or the like via wiring (not shown).

[0045] 3, the first electrode 61 and the second electrode 62 are formed of a pair of opposing patterns that contain at least a metal element and an organic component and are not directly connected to each other. When moisture adheres to any part between the first electrode 61 and the second electrode 62, the first electrode 61 and the second electrode 62 are electrically connected via the moisture, and the resistance between the first electrode 61 and the second electrode 62 decreases. Moisture can be detected by reading the change in resistance.

[0046] The metal element is preferably one that has high conductivity and excellent processability, and examples thereof include gold, silver, copper, nickel, tin, bismuth, lead, zinc, palladium, platinum, aluminum, tungsten, molybdenum, and carbon. These metals may be used alone or as alloys. The metal element is preferably contained in particulate form, and may be a mixture of two or more types of metal particles.

[0047] The organic component is not particularly limited, but examples thereof include monomers, oligomers, polymers, photopolymerization initiators, compounds having a carboxyl group, polymerization inhibitors, plasticizers, leveling agents, surfactants, silane coupling agents, antifoaming agents, and pigments.

[0048] When the first electrode 61 and the second electrode 62 contain a mixture or laminate of a metal element and an organic component, the electrodes have excellent adhesion to the substrate and are easy to process.

[0049] In FIG. 3, a comb-shaped pattern is shown as the shape of the opposing pattern, but the shape of the opposing pattern is not limited to this as long as the first electrode and the second electrode are in a shape that faces each other.

[0050] The opposing patterns formed by the first electrode 61 and the second electrode 62 determine the presence or absence of moisture by the decrease in resistance between the opposing patterns due to the adhesion of moisture. However, from the viewpoint of ease of determining the presence or absence of moisture using a circuit, it is preferable that the resistance between the opposing patterns due to contact with moisture be 10 MΩ or less.

[0051] The thickness of the sensor 30 is 1 mm or less. This is thin enough not to impair the wearing comfort of the wearer. From the viewpoint of both ease of handling during manufacturing of the sensor 30 and improving the wearing comfort of the absorbent article for the wearer, the thickness of the sensor is preferably 10 μm or more as a lower limit, more preferably 50 μm or more, and preferably 500 μm or less as an upper limit.

[0052] By adjusting the moisture absorption characteristics of the absorbent body 20, it is possible to control the time it takes for moisture excreted from the human body to reach the sensor 30 and the amount of moisture that reaches the sensor 30. This makes it possible to realize an absorbent article in which the sensor 30 detects moisture at a desired time or moisture absorption amount. Methods for adjusting the moisture absorption characteristics of the absorbent body 20 include adjusting the thickness of the core 21 and adjusting the material and composition of the core 21 (for example, changing the composition of the core 21 in the thickness direction).

[0053] There is no particular limitation on the method for communicating the detection of moisture to the wearer or the person changing the absorbent article after the sensor 30 detects moisture. Examples of such methods include a method in which the color of the sensor 30 changes, a method in which the sensor 30 emits light and / or sound, a method in which communication is performed between the sensor 30 and a reader by means of a magnetic field, an electric field, radio waves, ultrasonic waves, etc.

[0054] The substrate on which the moisture detection unit of the sensor 30 is formed is not particularly limited in material or configuration, as long as it has electrical insulation properties and can be processed to a thickness of 1 mm or less. A flexible substrate is preferred to allow the absorbent article to conform to the human body when worn. Furthermore, a substrate that is impermeable to moisture is also preferred. Specific examples of substrates include PET (polyethylene terephthalate) film, PP (polypropylene) film, PVC (polyvinyl chloride) film, and laminates thereof.

[0055] The thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of industrial processability, while it is preferably 1 mm or less, more preferably 500 μm or less, from the viewpoint of not reducing the wearing comfort of the absorbent article to the wearer.

[0056] Furthermore, when moisture adheres to a portion between the first electrode 61 and the second electrode 62, the moisture detection unit detects moisture by electrically connecting the first electrode 61 and the second electrode 62 via the moisture and reducing the resistance between the first electrode 61 and the second electrode 62. To properly allow moisture to adhere between the first electrode 61 and the second electrode 62, it is desirable that at least one of the first electrode 61 and the second electrode 62, and preferably both, be in contact with the wrap sheet. In other words, it is preferable that at least a portion of the conductor of the moisture detection unit be in contact with the wrap sheet.

[0057] Furthermore, in order to more appropriately attach moisture between the first electrode 61 and the second electrode 62, when the absorbent article is worn on the body and the wrap sheet deforms, it is preferable that the moisture detection unit also deforms along the shape of the wrap sheet. To achieve this, it is desirable that the moisture detection unit be no thicker than a certain thickness. The thickness of the moisture detection unit is preferably no thicker than 200 μm, more preferably no thicker than 100 μm.

[0058] Furthermore, the thickness of the first electrode 61 and the second electrode 62 is preferably thin, preferably 100 μm or less. This is because if the first electrode 61 and / or the second electrode 62 are thick, the aspect ratio of the space formed by the distance between the first electrode 61 and the second electrode 62 and the thickness of the first electrode 61 and the second electrode 62 becomes large, which may make it difficult for moisture to penetrate between the first electrode 61 and the second electrode 62. Having the thickness of the first electrode 61 and the second electrode 62 be 100 μm or less has the effect of making it easier for moisture to adhere between the first electrode 61 and the second electrode 62.

[0059] In the present embodiment 1, the sensor 30 is attached at approximately the center of the absorbent article 10 on a plane. This position corresponds to the crotch area of ​​the wearer. However, the attachment position of the sensor 30 is not particularly limited as long as the object of the present invention can be achieved. From the viewpoint of increasing the reliability of the sensor and minimizing discomfort felt by the wearer of the absorbent article, it is preferable that the sensor be placed in a part other than approximately the center of the absorbent article.

[0060] For example, in a modification of the first embodiment shown in Figure 4, the sensor 30 disposed between the back sheet 11 and the absorbent body 20 of the absorbent article 15 is positioned not in the approximate center on the plane of the absorbent article 15 but at a position shifted in the long side direction. In this embodiment, the stress applied to the sensor 30 is smaller than when the sensor 30 is positioned in the approximate center. This makes it possible to provide an absorbent article equipped with a more reliable sensor.

[0061] As described above, according to the first embodiment of the present invention, it is possible to provide an absorbent article that can accurately detect the generation of moisture with a simple configuration and that causes little discomfort to the wearer.

[0062] (Variation 1) Next, modified examples of the sensor used in the absorbent article according to the embodiment of the present invention will be described. Fig. 5 is a diagram schematically illustrating sensor modification 1. The sensor 32 shown in the figure includes an antenna unit 70 in addition to a moisture detection unit 60 on a substrate 40, but otherwise has the same configuration as the sensor 30 included in the absorbent article according to the first embodiment.

[0063] The antenna unit 70 has the function of communicating the state of the moisture detector 60 to a reading device external to the absorbent article 10 without being directly connected by wire to the reading device. As long as this function is possible, the material, shape, and method of the antenna unit 70 are not particularly limited.

[0064] 5, the shape of the antenna unit 70 is schematically illustrated as a so-called dipole antenna intended for communication with the outside world via radio waves, but is not limited to this. The antenna unit 70 can have an antenna shape suitable for various communication methods, such as using a loop antenna when communicating with the outside world via a magnetic field, as will be described later.

[0065] Regarding the method of communication with the outside, for example, when radio waves are used as a method of communication with the outside of the absorbent article 10, the following method can be used as an example. A reading device is placed outside the absorbent article 10, and the reading device irradiates the sensor with radio waves of a specific frequency, which are then received by the antenna unit 70. Therefore, by utilizing the fact that the state of the radio waves output from the antenna unit 70 changes depending on the state of the moisture detection unit 60, the state of the moisture detection unit 60 can be recognized.

[0066] Furthermore, for example, when a magnetic field is used as a method of communicating with the outside of the absorbent article 10, the following method can be used as an example. A reading device equipped with a loop-shaped antenna is placed outside the absorbent article 10, and a periodically changing magnetic field is applied from the loop-shaped antenna, causing an electromotive force to be generated in the antenna unit 70 by electromagnetic induction. The state of the current caused by this electromotive force changes depending on the moisture presence / absence state of the moisture detection unit 60, and the mutual inductance between the loop-shaped antenna of the reading device and the antenna unit 70 changes. By reading this change, the moisture presence / absence state of the moisture detection unit 60 can be recognized.

[0067] In order for the absorbent article 10 to efficiently communicate with an external reading device, it is preferable to use a material with high conductivity for the antenna portion 70. Specific examples of materials for the antenna portion 70 include the same materials as those for the conductors described above.

[0068] (Variation 2) 6 is a schematic diagram showing sensor variation 2. The sensor 34 shown in the figure includes a circuit section 80 in addition to a moisture detection section 60 and an antenna section 70, but otherwise has the same configuration as the sensor 32 shown in variation 1.

[0069] The circuit unit 80 is disposed between the moisture detection unit 60 and the antenna unit 70, and controls the moisture detection unit 60 as well as the antenna unit 70, thereby efficiently communicating between the absorbent article 10 and an external reading device. More specifically, the circuit unit 80 detects moisture by applying a DC voltage, an AC voltage, or a specific electrical signal to the moisture detection unit 60.

[0070] When, for example, a DC voltage is applied from circuit unit 80 to moisture detection unit 60, the current of the applied DC voltage source changes depending on whether moisture is present in moisture detection unit 60. By utilizing this phenomenon, the presence or absence of moisture can be recognized by circuit unit 80. Furthermore, when a specific electrical signal is applied from circuit unit 80 to moisture detection unit 60, the amount of change in that signal changes depending on whether moisture is present in moisture detection unit 60. By utilizing this phenomenon, the presence or absence of moisture can be recognized by circuit unit 80.

[0071] An example of applying a specific electrical signal from circuit unit 80 to moisture detection unit 60 is to output a square wave of a specific frequency from circuit unit 80 to moisture detection unit 60. By utilizing the phenomenon in which the square wave signal changes depending on the presence or absence of moisture in moisture detection unit 60, circuit unit 80 can recognize the presence or absence of moisture.

[0072] Furthermore, the circuit unit 80 can rectify the voltage generated by the antenna unit 70 and change the electrical characteristics of the antenna unit 70, such as the impedance, thereby enabling efficient communication between the antenna unit 70 and an external reading device.

[0073] The circuit unit 80 is preferably arranged on a substrate and is an assembly of functional elements designed to achieve a desired operation. Examples of functional elements include transistors, resistors, capacitors, and diodes, and the circuit unit 80 includes at least one of these.

[0074] The circuit unit 80 preferably includes a thin-film transistor containing carbon nanotubes, since this allows for the realization of a thin, inexpensive sensor. Figure 7 shows a schematic cross-sectional view of a thin-film transistor containing carbon nanotubes in the semiconductor layer. The thin-film transistor shown in Figure 7 includes a gate electrode 81, a gate insulating film 82, a semiconductor layer 85, a source electrode 83, and a drain electrode 84 formed on a substrate 43.

[0075] The substrate 43 may be separate from the substrate on which the sensor is formed, but is preferably common to (integrated with) the substrate on which the sensor is formed.

[0076] The material constituting the gate electrode 81 is preferably an inorganic substance containing at least one element selected from the group consisting of gold, copper, silver, nickel, tin, bismuth, lead, zinc, palladium, platinum, aluminum, tungsten, molybdenum, and carbon, but the material and the method of formation are not particularly limited as long as the desired electrical characteristics are obtained.

[0077] The material for the gate insulating film 82 is not particularly limited as long as it has the desired insulating properties. Examples include silicon oxide, siloxane, alumina, polyimide, etc. From the viewpoint of reducing manufacturing costs, it is preferable that the material for the gate insulating film 82 be a material that can be formed by printing technology.

[0078] The semiconductor layer 85 contains at least semiconducting carbon nanotubes, and controls the current between the source electrode 83 and the drain electrode 84 by an electric field from the gate electrode 81 via the gate insulating film 82. In order to control the current between the source and drain electrodes with high precision by the electric field from the gate electrode 81, it is preferable that the proportion of semiconducting carbon nanotubes is high. Specifically, it is preferable that 80% or more of the carbon nanotubes are semiconducting, and more preferably 90% or more of the carbon nanotubes are semiconducting.

[0079] More preferably, the semiconductor layer 85 includes a carbon nanotube composite having a conjugated polymer attached to at least a portion of the surface thereof. Examples of such a carbon nanotube composite include those disclosed in WO 2009 / 139339.

[0080] The material constituting the source electrode 83 and the drain electrode 84 may be any conductive material that can be generally used as an electrode. Examples include indium tin oxide (ITO), gold, silver, copper, aluminum, polysilicon, conductive polymers, and carbon materials. These electrode materials may be used alone, or multiple materials may be stacked or mixed for use. From the viewpoint of reducing manufacturing costs, it is preferable that the material constituting the source electrode 83 and the drain electrode 84 be a material that can be formed by printing technology.

[0081] With the above-described configuration, it is possible to form thin film transistors inexpensively by using methods such as screen printing, gravure printing, offset printing, inkjet printing, dispenser coating, nozzle coating, and drop cast coating in the manufacturing process of thin film transistors, which includes at least the formation of semiconductor layer 85. As a result, it is possible to realize a thin, highly functional circuit unit 80 at low cost.

[0082] In addition to thin film transistors, the circuit section 80 may also include functional elements such as diodes, resistors, and capacitors. There are no particular limitations on the type of functional element required, but from the viewpoint of manufacturing costs and not impairing the wearing comfort of the absorbent article for the wearer, it is preferable that the functional element be formed on a substrate using a printing technique.

[0083] From the viewpoint of detecting moisture with higher sensitivity, the sensor 34 is preferably a sensor that detects moisture by direct contact of the moisture detection unit 60 with moisture. On the other hand, direct contact with moisture causes deterioration of the circuit unit 80 and the antenna unit 70 due to changes in characteristics and corrosion. Therefore, it is preferable to provide a protective layer on these units to prevent direct contact with moisture.

[0084] In other words, it is preferable that the sensor 34 be configured so that no parts other than the moisture detection unit 60 come into contact with moisture. Specific examples of such configurations include a configuration in which the circuit unit 80 and the antenna unit 70 are provided with a moisture-impermeable protective layer, while the moisture detection unit 60 is provided with a moisture-permeable protective layer or no protective layer at all. By adopting such a configuration, it is possible to provide a sensor with superior durability. This point is preferably applicable not only to the sensor 34 according to this second modification, but also to sensors generally applicable to the present invention.

[0085] Furthermore, since the proximity of moisture, which is a dielectric, can cause fluctuations in the characteristics of the antenna unit 70, it is preferable that the antenna unit 70 be as far away from moisture as possible. Therefore, the antenna unit 70 is preferably disposed in a portion where the top sheet and the back sheet face each other without sandwiching an absorbent body between them. Such a portion is, for example, the peripheral portion of the absorbent article 10 according to the first embodiment of the present invention, an example of which is shown in FIG. 8. In the absorbent article 18 shown in FIG. 8, the sensor 34 is disposed across a portion where the top sheet and the back sheet face each other without sandwiching the absorbent body 20 between them, and a portion where the top sheet and the back sheet face each other with the absorbent body 20 sandwiched between them, and the antenna unit is disposed in the portion where the absorbent body 20 is not sandwiched between them. This arrangement prevents the antenna unit from coming into contact with the absorbent body 20, which absorbs and retains moisture, thereby suppressing fluctuations in the antenna unit's characteristics due to moisture.

[0086] It is not necessary that all of the antennas be positioned in opposing positions without sandwiching the absorbent body 20 between the top sheet and the back sheet; as long as the effect of moisture on the antennas can be reduced, it is acceptable for only a portion of the antennas to be positioned in opposing positions without sandwiching the absorbent body 20 between the top sheet and the back sheet.

[0087] 6 shows only one wire between the moisture detection unit 60 and the circuit unit 80, but this is for the sake of schematic illustration, and the number of wires in an actual sensor is not particularly limited. Similarly, in the following diagrams showing the sensor in a schematic manner, the number of wires between the moisture detection unit 60 and the circuit unit 80 is not limited to the number shown.

[0088] (Variation 3) 9 is a diagram schematically illustrating sensor variation 3. The sensor 36 shown in the figure has a moisture detection unit 60, an antenna unit 70, and a circuit unit 80 formed on the same surface of a substrate 40. The configuration of sensor 36 according to variation 3 is the same as that of sensors 32 and 34 shown in variations 1 and 2, except for the points described below.

[0089] In the sensor 36 according to the third modification, the moisture detection unit 60, antenna unit 70, and circuit unit 80 are formed on the same surface of the substrate 40, which reduces the thickness of the sensor compared to, for example, mounting a circuit made of an IC chip on the substrate or attaching a separately formed moisture detection sensor to the substrate. This makes it possible to provide a thin absorbent article that causes little discomfort to the wearer.

[0090] Here, for example, when we say that the moisture detection unit 60 is formed on the surface of the substrate 40, we mean that the moisture detection unit 60 is formed directly on the surface of the substrate 40, such as by printing at least one of the elements necessary to form the moisture detection unit using printing technology.

[0091] The printing technique refers to a technique for forming at least one of the materials constituting each part by printing it directly onto the substrate 40. Examples of printing methods include screen printing, gravure printing, offset printing, inkjet printing, dispenser coating, nozzle coating, and drop-cast coating.

[0092] As described above, in the method for manufacturing an absorbent article according to an embodiment of the present invention, it is preferable that the manufacturing process of the sensor includes printing technology.

[0093] Forming the moisture detection unit 60, antenna unit 70, and circuit unit 80 on the same surface allows for a simpler process for manufacturing the sensor than forming them on both sides. Furthermore, using the surface on which the moisture detection unit 60, antenna unit 70, and circuit unit 80 are not formed as the attachment portion to the absorbent article allows for a reduction in the overall sensor area. Forming the moisture detection unit 60 and circuit unit 80 on the same surface allows for integral formation of the moisture detection unit 60 and circuit unit 80, enabling more cost-effective manufacturing than when they are fabricated separately. Furthermore, using the same conductive material for at least one of the circuit unit 80 and the moisture detection unit 60 allows for the moisture detection unit 60 to be formed using one of the processes for forming the circuit unit 80. This simplifies the manufacturing process and reduces costs, and also eliminates the need for additional processes or materials for connecting the circuit unit 80 and the moisture detection unit 60.

[0094] (Variation 4) 10 is a diagram schematically illustrating sensor variation 4. Sensor 38 shown in the figure comprises a moisture detection unit 60 and a circuit unit 80 on a first substrate 41, and an antenna unit 70 on a second substrate 42. Other than that, it has the same configuration as sensor 36 shown in variation 3.

[0095] The first substrate 41 and the second substrate 42 are bonded at the portion indicated by the double-headed arrow between them. That is, the sensor 38 has a structure in which the substrate 41 on which the circuit section 80 is formed and the substrate 42 on which the antenna section 70 is formed are bonded together. The bonding area and bonding method are not particularly limited as long as electrical connection is established between the first substrate 41 and the second substrate 42 at necessary locations. For example, the substrate having the smaller area of ​​the first substrate 41 or the second substrate 42 may be bonded over its entire surface to the other substrate. Alternatively, only a portion of the substrate having the smaller area may be bonded to the other substrate. Examples of bonding methods include, but are not limited to, bonding using an adhesive or thermocompression bonding.

[0096] 10 shows a sensor in which the first substrate 41 is larger than the second substrate 42, but there is no particular limitation on the size relationship between them. Furthermore, there is no particular limitation on the relationship between the thicknesses of the first substrate 41 and the second substrate 42, but it is preferable that the second substrate 42 is thinner than the first substrate 41.

[0097] The configuration shown in Variation 4 makes it possible to fabricate some of the elements necessary for the sensor—the moisture detection unit, circuit unit, and antenna unit—on separate substrates, enabling the sensor to be manufactured with only the minimum manufacturing steps required for each element. For example, with the configuration shown in FIG. 10 , only the antenna unit needs to be manufactured on the second substrate 42, eliminating the need to go through the process of manufacturing functional elements required for the circuit unit 80, such as transistors, resistors, capacitors, and diodes. This eliminates the use of unnecessary materials during manufacturing and reduces the electricity and industrial water used in manufacturing, thereby reducing the environmental impact of sensor manufacturing.

[0098] Furthermore, the thicknesses of the first substrate 41 and the second substrate 42 can be freely selected depending on the respective functions, manufacturing process, and other conditions, making it possible to provide an absorbent article that is inexpensive and provides an improved wearing comfort for the wearer. Specifically, for example, the first substrate 41 includes the moisture detection unit 60 and the circuit unit 80, and therefore requires a relatively complex manufacturing process. To ensure smooth execution of this process and enhance control during the process, it is preferable to use a relatively thick substrate. On the other hand, the second substrate 42 includes only the antenna unit 70 and can be manufactured by simply forming a conductor pattern for the antenna. This reduces the number of manufacturing processes and heat treatment steps, allowing for the use of a relatively thin substrate. In other words, compared to when all elements are constructed from the same substrate, although the thickness of the bonded portion increases, the portion of the second substrate 42 alone can be made thinner. As a result, it is possible to provide a sensor with an improved wearing comfort as a whole.

[0099] It is desirable to manufacture the antenna unit 70 in a large size from the viewpoint of improving its characteristics such as communication distance and communication speed. On the other hand, it is desirable to manufacture the antenna unit 70 in a small size from the viewpoint of cost and comfort for the wearer. When determining the size of the antenna unit 70, it is desirable to consider these trade-off relationships and design it in light of the required characteristics.

[0100] In this case, as shown in Modification 4, a first substrate 41 is used to form the circuit section 80 and the moisture detection section 60, and a second substrate 42 is used to form the antenna section, and by thinning the second substrate 42, it is possible to reduce material costs and achieve a thickness that does not lead to increased discomfort for the wearer. In this way, restrictions on increasing the size of the antenna section 70 are reduced, and it is possible to improve the communication characteristics with the outside of the absorbent article.

[0101] When at least two substrates are bonded together as in Variation 4, electrical connection is required between the respective substrates. Therefore, it is generally preferable to achieve electrical connection by bonding the substrates together so that the conductive portions of each substrate are in physical contact with each other. Hereinafter, achieving electrical connection in this manner will be referred to as "achieving physical connection."

[0102] On the other hand, when physically connecting the substrates, it is necessary to strictly control the relative positions of the substrates before bonding them together, which is likely to increase costs. If such concerns arise, it is preferable to bond the substrates together so that the conductive portions of each substrate do not come into contact with each other. Hereinafter, achieving electrical connection in this manner will be referred to as "making a contactless connection." Making a contactless connection eliminates the need to strictly align the substrates with each other, making it possible to manufacture sensors more inexpensively.

[0103] For example, when a non-contact connection is made in a sensor having a circuit unit and an antenna unit, the conductive part of the circuit unit and the antenna are not in direct contact. That is, the conductive part of the circuit unit and the antenna are not in contact. Note that non-contact connection is possible not only in the sensor according to Modification 4, but also in the sensors according to Modifications 2 and 3 described above.

[0104] When a contactless connection is made, for example, in Modification 4, the electrical connection between the circuit unit 80 and the antenna unit 70 can be realized by using an electric field or a magnetic field, either singly or in combination. A method for achieving electrical connection by electric field coupling includes, for example, arranging patterns on the circuit unit 80 and the antenna unit 70 that are capacitively coupled to each other, and capacitively coupling the two via an electrically insulating material. Another method for achieving electrical connection by magnetic field coupling via the second substrate 42 includes, for example, forming loop-shaped conductor patterns on the circuit unit 80 and the antenna unit 70, and establishing an electrical connection between the two patterns by electromagnetic induction.

[0105] (Moisture detection system) Fig. 11 is a diagram schematically illustrating a moisture detection system 100 using an absorbent article 10 according to an embodiment of the present invention. The moisture detection system 100 shown in the figure is composed of the absorbent article 10 and a reading device 90, which is a means for wirelessly communicating with the absorbent article 10. The absorbent article 10 also includes the top sheet, absorbent body, back sheet, and the like shown in the embodiments so far, but these are omitted from Fig. 11.

[0106] Information on the presence or absence of moisture inside the absorbent article 10 can be communicated between the absorbent article 10 and the reading device 90 without connecting a physical line, and the moisture state of the absorbent article 10 can be detected by the reading device 90. Although not shown in Fig. 11, the reading device 90 is connected to a network line external to the device, and is equipped with a system that notifies the wearer or the worker who replaces the absorbent article as necessary.

[0107] By constructing the system described above, it becomes possible to notify the moisture status of the absorbent article, and by replacing the absorbent article when necessary, the wearer of the absorbent article can continue to feel comfortable. [Explanation of symbols]

[0108] 10 Absorbent articles 11 Back Seat 12 Topsheet 15 Absorbent articles 18 Absorbent articles 20 Absorbent 21 cores 22 Rap Sheet 30, 32, 34, 36, 38 sensors 40 Base material 41 First substrate 42 Secondary Substrate 43 Base material 60 Moisture detection unit 61 First electrode 62 Second electrode 63 Base material 70 Antenna section 80 Circuit section 81 gate electrode 82 Gate insulating layer 83 Source electrode 84 drain electrode 85 Semiconductor layer 90 Reading device 100 Moisture Detection System

Claims

1. An absorbent article comprising at least a top sheet, an absorbent body, a back sheet, and a sensor having a moisture detection unit, The absorbent body comprises a core that absorbs moisture and a wrap sheet that covers the core, the sensor is disposed between the wrap sheet and the back sheet of the absorbent body; The thickness of the sensor is 1 mm or less, the sensor has a circuit portion and an antenna portion, the circuit portion is provided on a first substrate, and the antenna portion is provided on a second substrate; An absorbent article characterized in that the conductive portion of the circuit portion and the antenna portion are configured to be out of contact with each other.

2. The absorbent article according to claim 1 , wherein the moisture detection portion includes a conductor, and at least a portion of the conductor is in contact with the wrap sheet.

3. The absorbent article according to claim 1 or 2, wherein the moisture detecting part has a thickness of 200 μm or less.

4. 4. The absorbent article according to claim 1, wherein the moisture detection part includes a conductor, and the conductor has a thickness of 100 μm or less.

5. The absorbent article according to any one of claims 1 to 4, wherein the sensor is configured so that no part other than the moisture detection portion comes into contact with moisture.

6. The absorbent article according to any one of claims 1 to 5, wherein the sensor has an antenna portion.

7. The absorbent article according to claim 6, wherein at least a part of the antenna portion is disposed in a portion where the top sheet and the back sheet face each other without sandwiching the absorbent body therebetween.

8. The absorbent article according to any one of claims 1 to 7, wherein the moisture detection unit includes a conductor, and the conductor is made up of one or more pairs of opposing patterns that contain at least a metal element and an organic component and are not directly connected to each other.

9. The absorbent article according to claim 8 , wherein the resistance between one or more pairs of opposing patterns that are not directly connected to each other of the moisture detection unit becomes 10 MΩ or less upon contact with moisture.

10. The absorbent article according to any one of claims 1 to 9, wherein the sensor has a circuit portion.

11. The absorbent article according to claim 10, wherein the sensor has the moisture detection section and the circuit section formed on the same surface of the same substrate.

12. The absorbent article according to claim 10 or 11, wherein at least one type of conductive material in the circuit portion is the same as the conductive material forming the moisture detection portion.

13. The absorbent article according to any one of claims 10 to 12, wherein the circuit portion includes a thin film transistor containing carbon nanotubes.

14. 14. The method for manufacturing an absorbent article according to claim 1, wherein a printing technique is included in the manufacturing process of the sensor.

15. A moisture detection system comprising the absorbent article according to any one of claims 1 to 13 and a transceiver device having means for wirelessly communicating with the absorbent article.

Images