JPWO2018180629A1 - Antenna, wireless communication device, biological signal measuring device, and clothing - Google Patents

Abstract

To provide an antenna, a wireless communication device, a biological signal measuring device, and clothing that have flexibility and do not deteriorate in performance after bending or repeated washing. The antenna of the present invention has a conductive fiber structure in which at least a conductive polymer containing a carbon atom is supported on the surface of a fiber having a diameter of 100 nm or more and 1000 nm or less and / or a gap between single fibers. In addition, a mixture of a conductive polymer and an olefin resin is used as a main component, and the conductive resin observed in a region of 15 to 30 μm from the surface layer is impregnated with an area ratio of 15% or more.

Description

  The present invention relates to an antenna, a wireless communication device using the same, a biological signal measuring device, and clothing. More specifically, the present invention relates to an antenna having a conductive fiber structure in which a conductive polymer containing at least carbon atoms is supported on fibers.

  In recent years, smart textiles incorporating electronic devices such as sensor devices (biological signal sensors, environmental sensors, acceleration sensors, etc.), signal processing devices, wireless communication devices, etc. in clothing have been developed, and healthcare, sports, workers A wide variety of developments are expected, such as watching systems for families and families, and entertainment.

  Among the electronic devices, a wireless communication device used for transmitting and receiving data has recently attracted attention. A wireless communication device is provided with an antenna for transmitting and receiving radio waves.A conventional antenna has a structure in which a conductive material such as a metal foil or conductive ink is formed on an insulating base material such as a plastic film. One in which the formed conductive pattern is formed can be given.

  In recent years, as an antenna for smart textiles, a flexible conductive pattern or base material is required from the viewpoint of the ability to follow the expansion and contraction of clothes, and an antenna using a conductive cloth is being studied. For example, Patent Document 1 proposes an RFID (Radio Frequency Identification) tag of an antenna in which a metal pattern is formed on an insulating cloth by vapor deposition or the like. Patent Document 2 proposes an RFID provided with an antenna using a conductive cloth made of a conductive fiber such as a metal-plated fiber (hereinafter, referred to as a cloth antenna).

JP 2013-171430 A Japanese Unexamined Patent Publication No. 2011-523820

  However, the techniques described in Patent Literatures 1 and 2 have a problem that the adhesion between the fiber and the metal is weak and the metal is a hard material, so that the conductive material is peeled or broken at the time of bending, and the antenna performance is changed. there were. Further, there is a problem that performance is deteriorated after repeated washing.

  The present invention has been made in view of the above problems, and has an object to provide an antenna, a wireless communication device, a biological signal measuring device, and clothing that have flexibility and do not deteriorate in performance after bending and repeated washing. I do.

  The inventor of the present invention has presumed that the above problem can be solved by supporting a conductive resin containing carbon atoms on a fiber having a specific diameter, and has conducted studies.

  That is, the present invention is an antenna having a conductive fiber structure in which at least a conductive resin containing a carbon atom is supported on the surface of a fiber having a diameter of 100 nm or more and 1000 nm or less and / or a gap between single fibers.

  Advantageous Effects of Invention According to the present invention, it is possible to provide an antenna, a wireless communication device, a biological signal measuring device, and clothing that have flexibility and do not deteriorate in performance after bending or repeated washing.

FIG. 1A is a diagram illustrating an example of the antenna of the present invention. FIG. 1B is a diagram illustrating an example of the antenna of the present invention. FIG. 1C is a diagram illustrating an example of the antenna of the present invention. FIG. 1D is an AA cross-sectional view of the antenna of FIG. 1C. FIG. 2 is a diagram illustrating an example of the antenna of the present invention. FIG. 3 is a diagram illustrating an example of the antenna of the present invention. FIG. 4 is a diagram illustrating an example of the antenna of the present invention. FIG. 5 is a sectional view showing an embodiment of the antenna of the present invention. FIG. 6 is a schematic diagram showing a measurement system of the XZ plane radiation pattern of the antenna of the present invention. FIG. 7 is a diagram showing the measurement results of the XZ plane radiation pattern of the antenna of the present invention. FIG. 8 is a diagram showing a human phantom used for measuring the antenna of the present invention. FIG. 9 is a diagram showing the measurement results of the XZ plane radiation pattern of the antenna according to the present invention. FIG. 10 is a scanning probe microscope photograph of the conductive fiber structure used for the antenna of the present invention.

Next, the antenna of the present invention will be described in detail.
The antenna of the present invention is an antenna having a conductive fiber structure in which at least a conductive resin containing carbon atoms is supported on the surface of a fiber having a diameter of 100 nm or more and 1000 nm or less and / or a gap between single fibers.

  The fibers constituting the conductive fiber structure of the present invention include natural fibers, synthetic or semi-synthetic fibers, and mixtures thereof. Examples of the natural fiber include cotton and silk, and examples of the synthetic fiber include polyester fiber, acrylic fiber, and nylon fiber, and examples of the semi-synthetic fiber include rayon, but are not limited thereto.

The diameter of the fiber constituting the conductive fiber structure of the present invention is preferably 100 nm or more and 1000 nm or less. When the thickness is 1000 nm or less, the surface area of the single fiber in the fiber structure is increased, and thus the adhesion between the conductive resin and the fiber is improved. As a result, it is possible to prevent the conductive resin from peeling off when the antenna is bent and to prevent performance degradation after repeated washing.
From the viewpoint of supporting the conductive resin on the surface and / or the gap between the single fibers, the thickness is more preferably 300 nm or more and 1000 nm or less, and further preferably 500 nm or more and 1000 nm or less. The upper limit is preferably 1000 nm or less, as described above, and more preferably 900 nm or less.

  In the conductive fiber structure of the present invention, from the viewpoints of conductivity, flexibility and high washing durability, a conductive resin is supported in the gap between the single fibers constituting the fiber structure and the thickness of the fiber structure. When the cross section in the direction is observed, the case where the area ratio of the conductive resin existing in the region of 15 to 30 μm from the surface layer is 15% or more is preferable because the washing durability is more excellent. When the conductive resin is carried in the gap between the single fibers, it can be impregnated to the deep part to obtain a conductive fiber structure with higher performance and better washing durability. It is. More preferably, the area ratio is 20% or more, whereby the durability of repeated washing is extremely excellent. As the upper limit, the area ratio is preferably 30% from the viewpoint of flexibility.

  The fiber constituting the conductive fiber structure of the present invention is a multifilament yarn made of a thermoplastic polymer, from the viewpoint of uniformity and fineness of the fiber fineness, and from the viewpoint of the adhesion between the fiber and the conductive resin. Preferably, there is.

  The thermoplastic polymer is not particularly limited as long as it is a polymer that can be fiberized, and polyethylene, a polyolefin-based fiber having polypropylene as a main component, a fibrous material for a chemical fiber such as acetate imparted with thermoplasticity, and a polyester, Examples include synthetic fiber polymers such as nylon, but are not limited thereto. Among them, a thermoplastic polymer represented by polyester or polyamide is important from the viewpoint of moldability. Many of polyesters and polyamides have a high melting point, and are more preferable. It is preferable that the melting point of the polymer is 165 ° C. or higher because the heat resistance is good. For example, polyethylene terephthalate (PET) has a temperature of 255 ° C. and nylon 6 (N6) has a temperature of 220 ° C. Other components may be copolymerized as long as the properties of the polymer are not impaired.

  Among thermoplastic polymers, fibers made of polyester are particularly preferable from the viewpoint of processability. As used herein, the polyester means terephthalic acid as a main acid component, and alkylene glycols having 2 to 6 carbon atoms, that is, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, preferably Examples of the polyester include at least one glycol selected from ethylene glycol and tetramethylene glycol, and particularly preferably a polyester containing ethylene glycol as a main glycol component.

  Further, a polyester in which a part of the terephthalic acid component is replaced with another difunctional carboxylic acid component may be used, and / or a polyester in which a part of the glycol component is replaced with a diol component other than the glycol component. You may.

  Examples of the bifunctional carboxylic acid other than terephthalic acid used herein include, for example, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, adipic acid, sebacic acid, and 1,4-cyclohexanedicarboxylic acid. And aromatic, aliphatic and alicyclic difunctional carboxylic acids. Examples of the diol compound other than the glycol include aromatic, aliphatic and alicyclic diol compounds such as cyclohexane-1,4-dimethanol, neopentyl glycol, bisphenol A and bisphenol S. .

  The polyester may be synthesized by any method. For example, if polyethylene terephthalate is described, usually, terephthalic acid and ethylene glycol are directly subjected to an esterification reaction, or a lower alkyl ester of terephthalic acid such as dimethyl terephthalate is subjected to a transesterification reaction with ethylene glycol, or Reacting terephthalic acid with ethylene oxide to form a glycol ester of terephthalic acid and / or a low polymer thereof, and heating the reaction product of the first step under reduced pressure. It can be produced by a second-stage reaction in which a polycondensation reaction is performed until a desired degree of polymerization is obtained.

  As a method for producing a multifilament, for example, an assembly of monofilament yarns produced by a known electrospinning method, a composite spinning method, or the like can be used. As an example of the composite spinning method, a sea-island composite fiber yarn composed of two polymers having different solubility is prepared as a nanofiber having a large number of single fibers, and the sea component of the sea-island composite fiber is removed with a solvent. , Ultrafine fibers. Although the thickness and distribution of each of the island components are not limited, a multifilament composed of nanofibers can be formed by reducing the diameter of the island components by a method such as increasing the number of the island components. In the present invention, it is preferable to include a nanofiber.

  The number of the island components is dependent on the fineness of the single fiber or the presence or absence of a twisted yarn on the single fiber, but is preferably 5 or more, preferably 24 or more, and more preferably 50 or more. As the number of single fibers increases, the space formed by a plurality of single fibers, that is, the portion where the conductive resin is supported is redifferentiated, so that the supportability of the conductive resin to the fiber structure increases. In addition, the continuity of the conductive resin is maintained even when the fiber is finely divided due to the reduced fiber diameter.

  The cross-sectional shape of the single fiber is not particularly limited to a round cross-section, a triangular cross-section, or any other shape having a high degree of irregularity.

  Further, in the present invention, it is also preferable to mix single fibers having different finenesses. Also, the cross-sectional form of the entire multicomponent fiber is not limited to a round hole, but may be any known fiber cross-section such as a trilobal type, a tetralobal type, a T type, and a hollow type.

  Examples of the fiber structure using the multifilament yarn of the present invention include those having the form of a mesh, papermaking, woven fabric, knitted fabric, nonwoven fabric, ribbon, string, or the like. It is used for those having various forms according to the purpose of use.

  The implementation of these fiber structures is not limited as long as the performance as an antenna such as dyeing and functional processing is not impaired by ordinary methods and means. Similarly, the present invention is not limited to surface physical processing such as raising the surface of the antenna, calendering, embossing, and water jet punching.

  In the conductive fiber structure of the present invention, the conductive resin containing at least carbon atoms is carried on the surface of the fiber and / or in the gap between the single fibers, and is preferably carried in the gap between the single fibers. Further, it is preferable that the conductive resin be present substantially continuously in the fiber axis direction in the gap between the single fibers constituting the multifilament yarn. In the case of this mode, the adhesion between the conductive resin and the single fiber is higher, and the conductivity is further higher, so that the gain is extremely higher than that of the antenna using the conventional conductive cloth, and as a result, The communication distance is further extended. In addition, since the conductive resin has a structure wrapped in fibers, the wavelength is shortened according to the dielectric constant of the fibers, and the antenna is reduced in size. Whether the conductive resin exists substantially continuously in the fiber axis direction in the gap between the single fibers is determined by examining the fracture surface of the conductive fiber structure in the fiber axis direction using a scanning electron microscope (SEM). ), The overlap of the conductive resin existing in the gaps of five randomly selected single fibers is observed from the obtained cross-sectional photograph, and if there is an overlap, it is determined that there is continuity. In the case where the conductive fiber structure is a woven fabric, the fracture surface in the fiber axis direction is a warp direction, and in the case of a knitted fabric, the fracture surface in the fiber axis direction is a direction in which a loop is present at a vertex of a loop when a loop exists. In the case where the loop does not exist in the knitted fabric or in the case of a non-woven fabric or the like, it is assumed that the fiber breaks in an arbitrary direction along the fiber axis direction. In addition, if other substances are attached to the conductive fibrous structure together with the conductive resin, elemental analysis of the elements constituting the conductive resin is appropriately performed to determine the presence of the conductive resin. I do. As a method of elemental analysis, a fracture surface in the fiber axis direction of the conductive fiber structure is observed with an energy dispersive X-ray (EDX) analyzer which is an auxiliary device of a scanning electron microscope (SEM), and the surface and There is a method for obtaining the amount of carbon atoms contained in the conductive resin carried in the single fiber gap, but the method is not limited thereto.

  As the conductive resin containing a carbon atom used in the present invention, for example, a resin having relatively low conductivity (hereinafter sometimes referred to as a low conductive resin) contains carbon black, carbon nanotubes, graphene, metal particles, and the like. Examples of the conductive resin include a conductive resin that has been given conductivity by conducting the treatment, and a conductive resin such as a conductive polymer in which the resin itself has conductivity, but is not limited thereto. These conductive resins have higher flexibility than metal materials, and deformation due to bending of the antenna does not remain after bending, and is excellent in bending resistance and characteristics after repeated washing. Furthermore, since the flexibility is high, an effect that the wearing comfort is good when wearing the clothes equipped with the antenna of the present invention can be obtained.

  In addition, from the viewpoint of stability of antenna characteristics at the time of expansion and contraction or bending, a conductive polymer is preferable. When a conductive polymer is used as the conductive resin, the conductivity of the conductive resin changes due to deformation of the conductive resin due to expansion and contraction or bending of the antenna, which may change the antenna characteristics. It is.

  The conductive polymer is not particularly limited as long as it is a polymer having conductivity, and examples thereof include an acetylene-based compound and a 5-membered heterocyclic ring (in addition to pyrrole, 3-methylpyrrole and 3-ethylpyrrole as monomers). 3-alkylpyrroles such as 3,4-dodecylpyrrole; 3,4-dialkylpyrroles such as 3,4-dimethylpyrrole and 3-methyl-4-dodecylpyrrole; N-alkyls such as N-methylpyrrole and N-dodecylpyrrole Pyrrole; N-alkyl-3-alkylpyrroles such as N-methyl-3-methylpyrrole and N-ethyl-3-dodecylpyrrole; pyrrole-based polymers obtained by polymerizing 3-carboxypyrrole; Molecule, isothianaphthene-based polymer, etc.), phenylene-based, aniline-based conductive polymers and their copolymers, Such as a liquid, and the like.

  Further, in a conductive polymer, a dopant has an effect on the conductivity. As the dopant used, a halide ion such as a chloride ion and a bromide ion, a perchlorate ion, a tetrafluoroborate ion, and a hexafluoride ion are used. Phosphate ions such as arsenate ion, sulfate ion, nitrate ion, thiocyanate ion, hexafluorosilicate ion, phosphate ion, phenylphosphate ion, hexafluorophosphate ion, trifluoroacetate ion, tosylate ion, ethylbenzene Sulfonate ions, alkylbenzenesulfonate ions such as dodecylbenzenesulfonate ion, alkylsulfonate ions such as methylsulfonate ion and ethylsulfonate ion, polyacrylate ion, polyvinylsulfonate ion, polystyrenesulfonate ion, poly ( -Acrylamide-2-methylpropanesulfonic acid) At least one kind of polymer ions such as ions are used. The amount of the dopant is not particularly limited as long as it has an effect on conductivity. is not.

  Examples of the conductive polymer include conductive polymers selected from polypyrrole, PEDOT (poly 3,4-ethylenedioxythiophene), and the like, as well as poly-4-styrene sulfonate (PSS), polyaniline, and polyparaphenylenevinylene. An embodiment in which a dopant selected from (PPV) is used in combination can be easily converted into a resin, and is preferably used as a conductive polymer. Hereinafter, when used together in such an embodiment, it may be represented by “/” as in PEDOT / PSS, for example.

  In particular, PEDOT / PSS (Denatron (registered trademark) manufactured by Nagase ChemteX Corporation) obtained by doping poly-4-styrene sulfonate PSS into PEDOT, a thiophene-based conductive polymer, is particularly suitable from the viewpoint of safety and processability. .

  The conductive resin preferably contains a binder resin from the viewpoint of durability. The binder resin is preferably at least one selected from the group consisting of an olefin resin, a polyester resin, a polyurethane, an epoxy resin, and an acrylic resin. As the binder resin, an olefin-based resin is most preferable in terms of bringing the components constituting the conductive resin in the conductive fiber structure into close contact with each other and more reliably imparting conductivity to the fiber structure.

  For example, from the viewpoint of repeated washing resistance, it is preferable to add an olefin resin to the conductive polymer. In particular, as the conductive resin to be supported on the fiber structure, it is preferable to use a conductive resin having an average particle diameter of 20 nm or less in dynamic light scattering measurement. Among them, when using a conductive resin mainly containing a mixture of a conductive polymer and an olefin-based resin, it is preferable to use the conductive resin having the average particle diameter of 20 nm or less. If the average particle size of the conductive polymer is too large, it is difficult to be supported in the gap between the single fibers of the fibers constituting the fiber structure and the single fibers, and is largely supported on the surface of the single fibers, and easily peeled off by physical impact, High conductivity after repeated washing cannot be maintained. When the average particle size of the conductive polymer is 20 nm or less, the conductive polymer is supported on the surface of the single fiber and the gap between the single fibers, and is less likely to be peeled off by physical impact, and retains high conductivity after repeated washing. it can. Here, the "main component" means that it occupies 50% or more of the mass ratio of the constituent materials other than the fibers of the conductive fiber structure.

  By using the conductive polymer and the olefin-based resin together, the compounds in the conductive fiber structure are brought into close contact with each other, and the conductive fiber structure can be formed more reliably. The olefin-based resin is preferably a non-polar olefin-based resin from the viewpoint of the flexibility and washing durability of the obtained conductive fiber structure. Here, in the present invention, “non-polar” means that the solubility parameter (SP) value is less than 6 to 10, preferably 7 to 9. This SP value is a value determined by the solubility.

  The non-polar olefin resin preferably has an SP value of less than 6 to 10. The nonpolar olefin-based resin may be used alone or in combination of two or more.

  Examples of the olefin-based resin include polyethylene, polypropylene, cycloolefin polymers (cyclic polyolefins), and modified polymers thereof. In a fiber structure having conductivity, these may be used as an olefin-based resin, or those obtained by modifying polyvinyl chloride, polystyrene, or the like with an olefin may be used as the olefin-based resin. These may be used alone or in combination of two or more.

  In the present invention, when the conductive resin is supported on the fibrous structure, a solvent may be added to form a treatment liquid, which may be used for processing. The solvent is not particularly limited and includes, for example, water; alcohols such as methanol, ethanol, 2-propanol, 1-propanol and glycerin; ethylene glycols such as ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol; ethylene. Glycol ethers such as glycol monomethyl ether, diethylene glycol monomethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether; glycol ether acetates such as ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate; propylene glycol, dipropylene Glycol, tripropylene Propylene glycols such as coal; propylene glycol monomethyl ether, propylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol diethyl ether Propylene glycol ether acetates such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate; tetrahydrofuran; acetone Acetonitrile. These solvents may be used alone or in combination of two or more.

  As the conductive fiber structure of the present invention, from the viewpoint of improving and stabilizing the conductivity, those further provided with glycerol, physiological saline and the like can be suitably used, but the present invention is not limited thereto.

  The conductive fiber structure of the present invention uses a precursor of the exemplified conductive resin, a solution of the conductive resin obtained by adding the above-described solvent to the conductive resin, an emulsion, and a treatment liquid such as a dispersion. It can be supported on the fiber structure by a known method such as a dipping method, a coating method, and a spray method. The method for supporting the fiber structure is not particularly limited. However, in order to support the conductive resin on the surface of the fiber and the gap between the single fibers, the conductive resin solution (emulsion, (Including a dispersion), or the number of times of spraying is preferably repeated a plurality of times. By repeatedly contacting the nanofiber with the conductive resin, the conductive resin can be filled between the single fibers so as to be continuous in the axial direction. In the present invention, it is preferable to heat the fiber structure after the treatment agent containing the conductive resin is carried on the fiber structure as described above. When heating, to give a heat history below the softening point of the component contained in the conductive resin, the decomposition temperature or less, so that the component is melted, penetrates further into the single fiber gap, and is firmly fixed. This is preferable in that further washing resistance can be imparted. The heating temperature is preferably 180C or lower, more preferably 80C to 180C, and even more preferably 100C to 150C. When the heating temperature is within the above range, the adhesiveness between the components constituting the conductive resin is good, and the conductivity can be more reliably imparted to the fibrous structure.

  In the antenna of the present invention, it is preferable that a resin layer is laminated on one surface of a conductive fiber structure containing a conductive resin. By covering one surface of the conductive fiber structure with the resin layer, the durability of the antenna, in particular, a decrease in conductivity due to the drop of the conductive resin due to washing can be significantly suppressed. The type and shape of the polymer constituting the resin layer are not limited, but are preferably a waterproof and moisture-permeable layer having insulating properties in view of required characteristics as an antenna.

  As the waterproof and moisture-permeable layer, known films, films, and laminates such as a PTFE (polytetrafluoroethylene) porous film, a nonporous film made of a hydrophilic elastomer such as a hydrophilic polyester resin and a polyurethane resin, and a microporous polyurethane resin film , A resin or the like, and a form laminated by a laminating method, but is not limited thereto. The waterproof and moisture-permeable layer is preferably formed by laminating and bonding a microporous polyurethane resin film having elasticity from a viewpoint of followability to the conductive fiber structure as a base material.

  The performance of the antenna is related to the surface resistivity of the conductive fiber structure to an alternating current having the same frequency as the frequency used for communication, and the surface resistivity is preferably 0.01 to 0.1 Ω / □. The frequency used for communication is not limited, but is preferably 100 MHz to 5 GHz from the viewpoint of communication performance such as communication distance, and particularly preferably 920 MHz or 2.45 GHz from the viewpoint of availability of communication devices. If the surface resistivity is larger than 0.1Ω / □, the current flowing through the antenna is small, and stable communication is difficult.

  Examples of the configuration of the antenna of the present invention include a laminate of a conductor and a dielectric made of the conductive fiber structure processed into an antenna shape. There is no particular limitation on the dielectric, and a fiber structure such as mesh, papermaking, woven fabric, knitted fabric, or nonwoven fabric, a polymer film such as polyethylene terephthalate, or a ceramic substrate such as alumina can be used. However, in general, when the relative dielectric constant of the dielectric is high, the loss when an alternating current flows through the antenna increases, and the frequency band becomes narrow, so that stable communication becomes difficult. Therefore, it is preferable that the relative permittivity of the dielectric be low. It is preferable to use an insulating substrate for the dielectric. Among the insulating base materials, the fibrous structure can be suitably used as an antenna for smart textiles because the fibrous structure contains air in the space between the fibers and has a low relative dielectric constant, and has a high flexibility. For example, the relative dielectric constant of a typical polymer film, polyethylene terephthalate film, is about 3.0, and the relative dielectric constant of polytetrafluoroethylene, which is a typical low dielectric polymer, is about 2.0. The relative permittivity of the nonwoven fabric shows a very low value of 1.4. Hereinafter, a case where an insulating fiber structure is used for the dielectric will be mainly described. The number of layers of the laminated body is not particularly limited, and a two-layer structure composed of a conductor composed of a conductive fiber structure and a dielectric, a first conductor composed of a conductive fiber structure, a dielectric and a conductive fiber A three-layer structure made of a second conductor made of a structure, a first conductor made of a conductive fiber structure, a first dielectric, a second conductor made of a conductive fiber structure, a second Examples include, but are not limited to, a dielectric, a third conductor made of a conductive fiber structure, and a six-layer structure made of a third dielectric.

  There is no particular limitation on the type of antenna of the present invention. For example, a loop antenna (see FIG. 1A) used for communication in an HF (High Frequency) band, a spiral antenna, and communication in a UHF (Ultra High Frequency) band. Examples include a dipole antenna (see FIG. 1B), a patch antenna (see FIGS. 1C and 1D), a microstrip antenna, a dipole array antenna, and a ring antenna.

  The loop antenna shown in FIG. 1A has an antenna 2 made of a conductive fiber structure formed in a loop on a dielectric 2 made of an insulating fiber structure. The dipole antenna shown in FIG. 1B is a laminate of a dielectric 2 made of an insulating fiber structure and a conductor 1 made of the conductive fiber structure processed into a specific pattern. Although FIG. 1B illustrates a meander-shaped antenna, the shape is not limited as long as it has antenna performance, and a linear structure as shown in FIG. 2 may be used. The width of the pattern is not particularly limited, and is designed from the viewpoint of antenna performance, pattern workability, and the like.

  The patch antenna shown in FIGS. 1C and 1D has a laminate of a first conductor 3A made of a conductive fiber structure, a dielectric 2 made of an insulating fiber structure, and a second conductor 3B made of a conductive fiber structure. The first and second conductors are electrically connected. The first conductor 3A plays a role of transmitting and receiving radio waves, and needs to be processed into a specific pattern shape. An example of the shape is the shape shown in FIG. 1C, but is not limited thereto. For example, the structure shown in FIG. 3, the square shown in FIG. 1C, and the circle shown in FIG. The replaced structure may be used. On the other hand, the second conductor 3B absorbs the radio wave radiated from the first conductor 3A and prevents the radio wave from radiating to the back of the antenna. The second conductor 3B does not need to be processed into a specific pattern shape.

  There is no particular limitation on the method of electrically connecting the first conductor 3A and the second conductor 3B. For example, a method of arranging a conductive fiber structure in the dielectric 2, a method of piercing a metal pin, A method using a metal button is exemplified. As the metal button, a male or female dot button is used. By engaging the male button arranged on the first conductor 3A and the second conductor 3B with the female button arranged on the dielectric 2, the first conductor 3A and the second conductor 3B are engaged. Are electrically connected. Note that a structure in which a female button is arranged on the first conductor 3A and the second conductor 3B and a male button is arranged on the dielectric 2 may be used.

  The method of processing the conductive fiber structure into a predetermined pattern is not particularly limited, and a known technique such as laser cutting, heat cutting, and die cutting can be used. The method of attaching the conductive fiber structure to the insulating fiber structure is not particularly limited, and a known technique such as sewing, heat sealing using an adhesive sheet, or using a button can be used. When the antenna of the present invention is attached to clothing, the antenna in which the conductive fiber structure is attached to the insulating fiber structure may be attached to the clothing, or the conductive fiber structure may be attached directly to the clothing. From the viewpoints of comfort, design, and the like, it is preferable to directly attach the conductive fiber structure to clothing.

  By combining the antenna of the present invention with a semiconductor circuit having a communication function, the antenna can be used as a wireless communication device. The wireless communication device is not particularly limited, and includes an RFID tag, a beacon, a BlueTooth (registered trademark) communication device, and the like. For example, by attaching these wireless communication devices to uniforms, it can be utilized for individual tracking of students at school, confirmation of attendance, and the like. In addition, by attaching these wireless communication devices to the hospitalization of inpatients, it can be used for individual tracking, individual authentication, and the like of inpatients.

  In the wireless communication device of the present invention, the number of antennas and semiconductor circuits is not limited, and one antenna and one semiconductor circuit may be used, or two or more antennas may be connected to one semiconductor circuit. In particular, by attaching a wireless communication device having two or more antennas to clothing, communication blind spots can be reduced. For example, by attaching the antenna of the present invention to the chest and the back, stable communication is possible regardless of the direction of the body with respect to the radio wave transceiver.

  There is no particular limitation on the method of connecting the antenna and the semiconductor circuit. Examples of the method include connecting a metal wire, a conductive yarn woven with a metal wire as a wire, and a connection using the conductive fiber structure according to the present invention. From the viewpoint of reducing the contact resistance by connecting the wiring between the antenna and the semiconductor circuit, it is preferable to use the conductive fiber structure of the present invention as the wiring. As shown in FIG. 4, it is particularly preferable that the first conductor 3A made of a conductive fiber structure functioning as an antenna and the conductive fiber structure used as the wiring 4 are integrated. By reducing the contact resistance, the loss when a high frequency signal is input from the semiconductor circuit 5 to the antenna is reduced, so that the communication distance can be increased.

  By combining the wireless communication device with various sensors, the wireless communication device can be used as a sensing device. There are no particular restrictions on the type of sensor, and sensors for acquiring environmental information such as temperature, humidity, illuminance, shock, and position, and heart rate, electrocardiographic waveform, respiratory rate, blood pressure, brain potential, myoelectric potential, etc. Examples include a biological electrode for acquiring a biological signal, and a biosensor for acquiring a blood glucose level, a cholesterol level, a hormone level, and the like. Note that the wireless communication device and the sensor may be connected using wiring or connected via wireless communication. By using these sensing devices, health management of daily life, monitoring of workers in factories, etc., leisure, exercise health management, remote management of heart disease, hypertension, sleep apnea syndrome, etc. will be possible. However, the present invention is not limited to these.

  Further, the wireless communication device in which the antenna and the semiconductor circuit of the present invention are combined can be used as a reader / writer antenna of an RFID tag. For example, when an RFID system is used to detect urination of an inpatient, it is necessary to install a reader / writer antenna on the bed. Since the hospital bed needs to be bent to wake up the body, the reader / writer antenna is required to have bending resistance. Since the antenna of the present invention is rich in flexibility and excellent in bending resistance, it can be suitably used as a reader / writer antenna for a hospital bed.

  Hereinafter, the present invention will be described more specifically based on examples. Note that the present invention is not limited to the following examples.

(1) Production method of conductive fiber structure 75T- of an alkaline hot water-soluble polyester made of polyethylene terephthalate as an island component and a copolymer of terephthalic acid and 5-sodium sulfoisophthalic acid as an acid component of a sea component as a polyester acid component 100T-136F in which nanofibers with a single fiber diameter of 700 nm of 112F (sea / island ratio: 30%: 70%, number of islands 127 / F) and high contraction yarn of polyethylene terephthalate with a single fiber diameter of 22.85 μm of 22T-24F are mixed. A circular knit was knitted with a smooth structure using the polyester nanofiber mixed yarn of the above. Next, the fabric was immersed in a 3% by mass aqueous solution of sodium hydroxide (75 ° C., bath ratio 1:30) to remove easily soluble components to obtain a knitted fabric using a mixed fiber of nanofiber and high shrinkage yarn. The knitted fabric has a density of 58 × 78 (books / in) and a basis weight of 118 (g / cm ² ). "Denatron FB408B" (manufactured by Nagase ChemteX Corporation) as a dispersion containing a conductive polymer and an olefin resin is applied to the knitted fabric as the obtained fiber structure by a known knife coating method. Then, the temperature was controlled in the range of 120 ° C to 130 ° C and heated. The conductive resin adhesion amount of the obtained conductive structure was 12.3 g / m ² . In addition, it is confirmed by (3) the conductive resin content area ratio described later that the conductive resin is substantially continuously present in the fiber axis direction in the gap between the single fibers constituting the multifilament yarn. did. FIG. 10 is a cross-sectional photograph using the conductive resin structure impregnated area ratio of the conductive fiber structure for evaluation. FIG. 10 shows that the resistance from the surface layer to 30 μm is low, that is, the conductive resin is impregnated. Further, the surface resistivity of the manufactured conductive fiber structure was 0.045Ω / □.

(2) Fiber diameter The multifilament extracted from the fiber was embedded in an epoxy resin, frozen with a Reichert FC / 4E cryosectioning system, and cut with a Reichert-Nissei ultracut N (ultramicrotome) equipped with a diamond knife. Thereafter, the cut surface was photographed at 5,000 times for the nanofiber, 1,000 times for the microfiber, and 500 times for the others with a VE-7800 scanning electron microscope (SEM) manufactured by Keyence Corporation. From the obtained photographs, 150 ultrafine fibers selected at random were extracted, and all circumscribed circle diameters (fiber diameters) of the photographs were measured using image processing software (WINROOF).

(3) Conductive resin impregnated area ratio When observing the cross section in the thickness direction of the conductive fiber structure, the area ratio of the conductive resin existing in the region of 15 to 30 μm from the surface layer (conductive resin impregnated area ratio) is It was determined as follows.
Using an argon (Ar) ion beam processing apparatus, the conductive fiber structure was cut in the thickness direction to prepare a thin-film section having a cross section, which was used as a measurement sample. A voltage is applied to the obtained sample for measurement from the back side of the sample for measurement using a scanning probe resistance microscope (hereinafter referred to as SSRM), and conduction of the surface layer of the sample is performed using a conductive probe. Was observed. In the observed image, as shown in the cross-sectional image of FIG. 10, a 30 μm × 30 μm square area is set so that the highest part of the surface layer of the fiber structure is in contact with the upper part of the visual field. A 15 μm × 30 μm area 15 μm below the highest position of the surface layer portion is set to a threshold of 60 using image processing software (GIMP 2.8 portable), and 15 to 15 μm from the surface of the conductive fiber structure in the thickness direction. The area ratio of the 30 μm region impregnated with the conductive resin was determined. At this time, the number of observations was measured at 20 randomly selected cross sections. The average value of the respective area ratios determined at the 20 locations was calculated, and this was defined as the “conductive resin-impregnated area ratio”. This confirmed that the “conductive resin impregnated area ratio” of the conductive fiber structure manufactured in (1) was 20.7%.
Observation device: NanoScope Iva AFM manufactured by Bruker AXS, Digital Instruments
Dimension 3100 stage AFM system + SSRM option SSRM scanning mode: Simultaneous measurement of contact mode and spreading resistance SSRM tip (Tip): Diamond coated silicon cantilever Tip part number: DDESP-FM (manufactured by Bruker AXS)
Ar ion beam processing equipment: IM-4000 manufactured by Hitachi High-Technologies Corporation, acceleration voltage 3kV

(4) Dispersion particle size of conductive polymer The conductive polymer dispersed in the dispersion liquid is filtered with a Sartorius Minisart 0.2 μm syringe filter to determine whether the dispersion particle size of the conductive polymer is less than 200 nm. Was measured. It was confirmed that the conductive polymer in “Denatron FB408B” used in (1) had a dispersed particle diameter of less than 200 nm.

(5) Average particle size of conductive polymer (dynamic light scattering method)
The average particle size of a 50-fold diluted conductive polymer obtained by adding 1 g of a conductive polymer to 49 g of water while stirring was measured using a Nanotrac Wave series manufactured by Microtrac. Specifically, the particle diameter distribution was determined by measuring the volume resistance diameter, and the hydrodynamic diameter median diameter was calculated to be the average particle diameter. The average particle size of the conductive polymer in “Denatron FB408B” used in (1) was 20 nm or less.

(6) Method of Measuring Conductivity of Conductive Fiber Structure Conductive fiber structure prepared by the method described in (1) as a strip conductor, and using 2 mm thick polytetrafluoroethylene for a substrate, A half-wavelength microstrip line resonator A having an impedance of 50Ω was prepared. The length of the strip conductor was 42 mm, the width was 3 mm or 6 mm, both ends were open, and the resonance frequency was about 2.4 GHz. Is excited from one of the coaxial cable of the half-wave microstrip line resonator A, connects the network analyzer unloaded Q value (Q _A) was measured in the other of the coaxial cable. Further, except for using a copper foil as a strip conductor, like the half-wave microstrip line resonator A, creating a half-wave microstrip line resonator B, the unloaded Q value (Q _B) was measured. _Assuming that Q _Sample is a Q value caused by loss of the conductive fiber structure strip and Q _Cu is a Q value caused by loss of the copper foil strip, 1 / Q _A −1 / Q _B = 1 / Q _Sample −1 / The relationship of Q _Cu holds. Q _Cu was calculated from the surface resistivity of the copper foil, the value was applied to the above equation to calculate Q _Sample , and the results were used to calculate the surface resistivity and conductivity of the conductive fiber structure. .

(7) Measurement method of reflection coefficient Using a conductive fiber structure made of the method described in (1) or a conductive fiber structure made of silver-plated fiber and a non-woven fabric, at 2.4 GHz shown in FIG. A radiating measurement antenna was fabricated. Note that a dielectric 2 made of a non-woven fabric is disposed between a first conductor 3A made of a conductive fiber structure and a second conductor 3B, and the first conductor 3A and the second conductor 3B are placed between the first conductor 3A and the second conductor 3B. Were electrically connected using a metal button 7. Using the coaxial cable terminal 6, the prepared antenna was connected to a network analyzer (N5230C, manufactured by Agilent Technologies), and the reflection coefficient was measured.

(8) Measurement method of XZ plane radiation pattern As shown in FIG. 6, the measurement antenna prepared in (7) was installed on a turntable, and used as a network analyzer (N5230C, manufactured by Agilent Technologies). The turntable was rotated by 7.5 degrees, and at each rotational position, a radio wave was transmitted from the transmitting antenna connected to the network analyzer to the measuring antenna to measure the gain. The radiation pattern was measured using an anechoic chamber for two types of horizontal polarization and vertical polarization.

(9) Amount of Conductive Resin Adhesion The amount of the conductive resin adhered was measured by a change in mass of the fibrous structure as a test cloth before and after the application of the conductive resin dispersion in a standard state (20 ° C. × 65% RH). The calculation formula is as follows.
Conductive resin adhesion amount (g / m ² ) =
(Mass of test cloth after processing (g) −Mass of test substance before processing (g)) / Area to which dispersion liquid of test cloth was applied (m ² )

Example 1
When the surface resistivity and the conductivity of the conductive fiber structure prepared by the method described in (1) were measured by the method described in (6), the surface resistivity was 0.045 Ω / □, and the conductivity was 4.76 μS / m. The reflection coefficient measured by the method described in (7) was -17.2 dB. The XZ plane radiation pattern measured by the method described in (8) is indicated by a broken line in FIG.

Comparative Example 1
A circular knit was knitted using nickel / copper plated fiber (MK-KTN260, manufactured by Tanimura Corporation). The surface resistivity and conductivity measured by the method described in (6) are 0.050 Ω / □, 3.84 μS / m, respectively, and the reflection coefficient measured by the method described in (7) is −15.2 dB. there were. The XZ plane radiation pattern measured by the method described in (8) is shown by a solid line in FIG.
From the XZ plane radiation pattern of FIG. 7, the gain of the antenna of Example 1 was 0.4 dB higher than that of Comparative Example 1, and the communication distance was increased by 6%.

Example 2
The reflection coefficient and the XZ plane radiation pattern were measured in the same manner as in Example 1 except that the measurement antenna manufactured in (7) was attached to the human body phantom shown in FIG. The reflection coefficient is -17.3 dB, and the XZ plane radiation pattern is indicated by a broken line in FIG. The human body phantom is designed with a human body having a relative dielectric constant of 53.6 and a conductivity of 1.81 S / m.

Comparative Example 2
The reflection coefficient and the XZ plane radiation pattern were measured in the same manner as in Example 2 except that the antenna manufactured in Comparative Example 1 was used. The reflection coefficient is -15.0 dB, and the XZ plane radiation pattern is shown by the solid line in FIG.
From the XZ plane radiation pattern of FIG. 9, the gain of the antenna of Example 2 was 0.4 dB higher than that of Comparative Example 2, and the communication distance was increased by 6%.

Reference Signs List 1 conductor 2 dielectric 3A first conductor 3B second conductor 4 wiring 5 semiconductor circuit 6 coaxial cable terminal 7 metal button

Claims (14)

  An antenna having a conductive fiber structure in which at least a conductive resin containing carbon atoms is supported on the surface of a fiber having a diameter of 100 nm or more and 1000 nm or less and / or a gap between single fibers.   The conductive resin is carried in the gap between the single fibers constituting the fibrous structure and the single fibers, and when the cross section in the thickness direction of the fibrous structure is observed, the conductive resin is present in a region of 15 to 30 μm from the surface layer. The antenna according to claim 1, further comprising a conductive fiber structure having a resin area ratio of 15% or more.   The antenna according to claim 2, wherein the conductive resin is a conductive resin containing a conductive polymer.   The antenna according to any one of claims 1 to 3, wherein the conductive resin further includes a binder resin.   The antenna according to claim 4, wherein the binder resin is an olefin-based resin.   The antenna according to claim 2, wherein the conductive polymer is poly (3,4-ethylenedioxythiophene) and polystyrenesulfonic acid.   The fiber is a multifilament yarn made of a thermoplastic polymer, and the conductive resin is present substantially continuously in the fiber axis direction in a gap between the single fiber and the single fiber constituting the multifilament yarn. The antenna according to any one of claims 1 to 6, wherein:   The antenna according to any one of claims 1 to 7, wherein a surface resistivity of the conductive fiber structure measured at 920 MHz to 3 GHz is 0.01 to 0.1 Ω / □.   The antenna according to any one of claims 1 to 8, comprising a laminate of a conductor and a dielectric made of the conductive fiber structure.   The first conductor made of the conductive fiber structure, the dielectric, the second conductor made of the conductive fiber structure are laminated in this order, the first conductor and the second conductor The antenna according to claim 9, wherein the body is electrically connected.   The antenna according to any one of claims 1 to 10, further comprising a wiring made of the conductive fiber structure.   A wireless communication device having at least the antenna according to any one of claims 1 to 9 and a semiconductor circuit.   A biological signal measuring device comprising at least the antenna according to any one of claims 1 to 11 and a biological electrode.   A garment comprising a plurality of antennas according to any one of claims 1 to 11, wherein at least one of the garments is attached to a portion different from other antennas.

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