WO2018180629A1

WO2018180629A1 - Antenna, wireless communication device, biometric signal measurement device, and garment

Info

Publication number: WO2018180629A1
Application number: PCT/JP2018/010556
Authority: WO
Inventors: 典子長井; 潤史脇田; 応明高橋
Original assignee: 東レ株式会社; 国立大学法人千葉大学
Priority date: 2017-03-30
Filing date: 2018-03-16
Publication date: 2018-10-04
Also published as: JPWO2018180629A1; JP6999139B2; TW201841129A

Abstract

The purpose of the present invention is to provide an antenna which is flexible and of which performance is not decreased after bending or repeated washing, a wireless communication device, a biometric signal measurement device, and a garment. The antenna of the present invention comprises, at least, an electrically conductive fiber structure in which an electrically conductive polymer including carbon atoms is carried on a surface and/or in a monofilament gap of fibers with a diameter of not less than 100 nm and not more than 1000 nm. The antenna is characterized in that a mixture of the electrically conductive polymer and an olefin-based resin is used as a primary component, and that a conductive resin observed in a region of 15 to 30 μm from an upper layer is impregnated with an area ratio of not less than 15%.

Description

Antenna, wireless communication device, biological signal measuring device, and clothes

The present invention relates to an antenna, a wireless communication device using the antenna, a biological signal measuring device, and clothes. Specifically, the present invention relates to an antenna having a conductive fiber structure in which a conductive polymer containing at least a carbon atom is supported on a fiber.

In recent years, the development of smart textiles that incorporate electronic devices such as sensor devices (biological signal sensors, environmental sensors, acceleration sensors, etc.), signal processing devices, and wireless communication devices into clothing has been promoted. A wide range of development is expected, such as watching systems for family members and family members, and entertainment.

Among the electronic devices, in recent years, wireless communication devices used for data transmission / reception have attracted attention. The wireless communication device is provided with an antenna for transmitting and receiving radio waves, and the structure of a conventional antenna is that a conductive material such as a metal foil or conductive ink is formed on an insulating substrate such as a plastic film. The thing in which the formed conductive pattern was formed is mentioned.

In recent years, as an antenna for smart textiles, flexibility is required for conductive patterns and base materials from the viewpoint of conformity to the expansion and contraction of clothes, and antennas using conductive cloth have been studied. For example, Patent Document 1 proposes an RFID (Radio Frequency IDentification) tag for 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 including an antenna (hereinafter referred to as a cloth antenna) using a conductive cloth made of a conductive fiber such as a metal-plated fiber.

JP 2013-171430 A Special table 2011-523820

However, in the techniques described in

Patent Documents

1 and 2, since the adhesion between the fiber and the metal is weak and the metal is a hard material, there is a problem that the antenna material changes when the conductive material is peeled or broken during bending. there were. Furthermore, there has been a problem that the performance decreases after repeated washing.

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

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

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 to 1000 nm and / or a single fiber gap.

According to the present invention, it is possible to provide an antenna, a wireless communication device, a biological signal measuring device, and clothes that have flexibility and whose performance does not deteriorate after bending or repeated washing.

FIG. 1A is a diagram illustrating an example of an 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 for explaining an example of the antenna of the present invention. FIG. 5 is a cross-sectional view showing an embodiment of the antenna of the present invention. FIG. 6 is a schematic view showing a measurement system for the XZ plane radiation pattern of the antenna of the present invention. FIG. 7 is a diagram showing the measurement result of the XZ plane radiation pattern of the antenna of the present invention. FIG. 8 is a diagram showing a human phantom used for measurement of the antenna of the present invention. FIG. 9 is a diagram showing the measurement result of the XZ plane radiation pattern of the antenna of the present invention. FIG. 10 is a scanning probe microscope observation photograph of the conductive fiber structure used in 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 a carbon atom is supported on the surface of a fiber having a diameter of 100 nm to 1000 nm and / or a single fiber gap.

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

As a diameter of the fiber which comprises the electroconductive fiber structure of this invention, 100 nm or more and 1000 nm or less are preferable. By setting it to 1000 nm or less, the surface area of the single fiber in the fiber structure is increased, so that the adhesion between the conductive resin and the fiber is improved. As a result, peeling of the conductive resin when the antenna is bent and performance deterioration after repeated washing can be suppressed.
From the viewpoint of supporting the conductive resin on the surface and / or the single fiber gap, it 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, but more preferably 900 nm or less.

In the conductive fiber structure of the present invention, from the viewpoint of conductivity, flexibility, and high washing durability, the 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, it is preferable in that the washing durability is more excellent when the area ratio of the conductive resin existing in the region of 15 to 30 μm from the surface layer is 15% or more. When conductive resin is carried in the gap between single fibers, it can be impregnated deeply to obtain a conductive fiber structure with even higher performance and excellent washing durability. It is. More preferably, the area ratio is 20% or more, which makes the repeated washing durability extremely excellent. As an upper limit, the area ratio is preferably 30% from the viewpoint of flexibility.

The fibers constituting the conductive fiber structure of the present invention are multifilament yarns made of a thermoplastic polymer from the viewpoints of uniformity and fineness of the fineness of the fibers and the adhesion between the fibers and the conductive resin. Preferably there is.

The thermoplastic polymer is not particularly limited as long as it is a polymer that can be made into a fiber. Polyolefin fiber mainly composed of polyethylene, polypropylene, etc., fiber for chemical fiber such as acetate imparted with thermoplasticity, and polyester, Examples thereof include, but are not limited to, polymers for synthetic fibers such as nylon. Especially, it is important from the point of the moldability that it is a thermoplastic polymer represented by polyester and polyamide. Many polyesters and polyamides have a high melting point, and are more preferable. The melting point of the polymer is preferably 165 ° C. or higher because the heat resistance is good. For example, polyethylene terephthalate (PET) is 255 ° C., nylon 6 (N 6) is 220 ° C., and 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. The polyester here refers to terephthalic acid as the main acid component, and alkylene glycol having 2 to 6 carbon atoms, that is, ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, preferably Examples include polyesters having at least one glycol selected from ethylene glycol and tetramethylene glycol as a main glycol component, particularly preferably ethylene glycol.

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

Examples of the bifunctional carboxylic acid other than terephthalic acid used here include isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, adipic acid, sebacic acid, and 1,4-cyclohexanedicarboxylic acid. Examples thereof include aromatic, aliphatic and alicyclic bifunctional 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, when describing polyethylene terephthalate, terephthalic acid and ethylene glycol are usually esterified directly, or a lower alkyl ester of terephthalic acid such as dimethyl terephthalate is transesterified with ethylene glycol, or A first stage reaction in which terephthalic acid and ethylene oxide are reacted to form a glycol ester of terephthalic acid and / or a low polymer thereof, and the reaction product of the first stage is heated 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 achieved.

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

The number of island components is 5 or more, preferably 24 or more, and more preferably 50 or more, although there is a relationship with the single fiber fineness or the presence or absence of twisted yarns on single fibers. As the number of single fibers increases, voids composed of a plurality of single fibers, that is, portions where the conductive resin is supported are re-differentiated so that the conductive resin is supported on the fiber structure. In addition, the continuity of the conductive resin is maintained even if the fiber diameter is reduced to be finely divided.

The cross-sectional shape of the single fiber is not particularly limited even if it is a round cross-section, a triangular cross-section, or any other irregular cross-section having a high degree of deformity.

Furthermore, in the present invention, it is also preferable to mix single fibers having different finenesses. The cross-sectional form of the entire multicomponent fiber is not limited to a round hole, but includes cross-sections of all known fibers 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 forms such as mesh, papermaking, woven fabric, knitted fabric, nonwoven fabric, ribbon, and string. Used in various forms according to the purpose of use.

These fiber structures are not limited to implementation unless the performance as an antenna such as dyeing and functional processing is impaired by ordinary methods and means. The surface physical processing such as raising of the antenna surface shape, calendering, embossing, water jet punching is not limited in the same manner.

In the conductive fiber structure of the present invention, the conductive resin containing at least carbon atoms is supported on the fiber surface and / or on the single fiber gap, and preferably on the single fiber gap. Furthermore, it is preferable that the conductive resin is in a form that is substantially continuously present in the fiber axis direction in the gap between the single fibers constituting the multifilament yarn. In the case of this aspect, the adhesion between the conductive resin and the single fiber is even higher, and the conductivity is even higher, so the gain is extremely higher than the antenna using the conventional conductive cloth, and as a result, The communication distance is further increased. 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 becomes small. Whether or not 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 in the fiber axis direction of the conductive fiber structure with a scanning electron microscope (SEM). ), And the overlapping of the conductive resin existing in the gap between the five single fibers randomly selected from the obtained cross-sectional photograph is observed, and if there is an overlap, it is determined that there is continuity. When the conductive fiber structure is a woven fabric, the fracture surface in the fiber axis direction is the warp direction, and when the conductive fiber structure is a knitted fabric, the fracture surface in the fiber axis direction is a direction in which the loop is split at the apex of the loop when a loop exists in the stitch ( When the loop does not exist in the knitted fabric, the nonwoven fabric or the like breaks in any direction along the fiber axis direction. In addition, if other materials are also attached to the conductive fiber structure along with the conductive resin, perform analysis that allows elemental analysis of the elements that make up the conductive resin, and identify the presence of the conductive resin. To do. As a method of elemental analysis, the 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 accessory device of a scanning electron microscope (SEM) device, 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 this is not a limitation.

Examples of the conductive resin containing carbon atoms used in the present invention include carbon black, carbon nanotubes, graphene, metal particles, etc., in a resin having a relatively low conductivity (hereinafter sometimes referred to as a low conductive resin). Examples thereof include, but are not limited to, a conductive resin such as a conductive resin imparted with conductivity and a conductive polymer in which the resin itself has conductivity. These conductive resins have higher flexibility than metal materials, and deformation due to bending of the antenna does not remain after bending, and are excellent in resistance to bending and characteristics after repeated washing. Furthermore, since the flexibility is high, there is also an effect that the comfort is good when wearing the clothes equipped with the antenna of the present invention.

Note that a conductive polymer is preferable from the viewpoint of stability of antenna characteristics during expansion and contraction and bending. When a conductive polymer is used as the conductive resin, the conductivity of the conductive resin changes due to the deformation of the conductive resin caused by expansion / contraction or bending of the antenna. As a result, the antenna characteristics may change. It is.

The conductive polymer is not particularly limited as long as it is a polymer exhibiting conductivity. For example, acetylene-based, 5-membered heterocyclic ring (as monomer, pyrrole, 3-methylpyrrole, 3-ethylpyrrole) 3-alkylpyrrole such as 3-dodecylpyrrole; 3,4-dialkylpyrrole such as 3,4-dimethylpyrrole and 3-methyl-4-dodecylpyrrole; N-alkyl such as N-methylpyrrole and N-dodecylpyrrole Pyrrole; N-alkyl-3-alkylpyrrole such as N-methyl-3-methylpyrrole and N-ethyl-3-dodecylpyrrole; pyrrole polymer obtained by polymerizing 3-carboxypyrrole, etc. Molecules, isothianaphthene-based polymers, etc.), phenylene-based and aniline-based conductive polymers and their copolymers, Such as emissions liquid, and the like.

Furthermore, in conductive polymers, dopants have an effect on the conductivity. The dopants used here include halide ions such as chloride ions and bromide ions, perchlorate ions, tetrafluoroborate ions, hexafluoride ions and hexafluoride ions. Arsenate ion, sulfate ion, nitrate ion, thiocyanate ion, hexafluorosilicate ion, phosphate ion, phenylphosphate ion, hexafluorophosphate ion, trifluoroacetate ion, tosylate ion, ethylbenzene Alkyl benzene sulfonate ion such as sulfonate ion, dodecylbenzene sulfonate ion, alkyl sulfonate ion such as methyl sulfonate ion, ethyl sulfonate ion, polyacrylate ion, polyvinyl sulfonate ion, polystyrene sulfonate ion, poly Among polymer ions such as (2-acrylamido-2-methylpropanesulfonic acid) ion, at least one ion is used. The amount of dopant added is particularly limited as long as it is an amount that has an effect on conductivity. It is not a thing.

Examples of the conductive polymer include polypyrrole, PEDOT (poly3,4-ethylenedioxythiophene), and the like, and poly-4-styrene sulfonate (PSS), polyaniline, and polyparaphenylene vinylene. An embodiment in which a dopant selected from (PPV) is used in combination is easy to resinize and is preferably used as a conductive polymer. Hereinafter, the case of using in combination in this manner may be represented by “/”, for example, PEDOT / PSS.

In particular, PEDOT / PSS (Denatron (registered trademark) manufactured by Nagase ChemteX Corporation) in which PEDOT of thiophene-based conductive polymer is doped with poly 4-styrenesulfonate PSS is particularly suitable from the viewpoint of safety and workability. .

It is preferable from the viewpoint of durability that the conductive resin contains a binder resin. The binder resin is preferably at least one selected from the group consisting of an olefin resin, a polyester resin, polyurethane, an epoxy resin, and an acrylic resin. As the binder resin, an olefin resin is most preferable from the viewpoint of bringing the compound 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, it is preferable to use a conductive resin having an average particle diameter of 20 nm or less in dynamic light scattering measurement as the conductive resin to be carried on the fiber structure. Among these, when using a conductive resin whose main component is a mixture of a conductive polymer and an olefin resin, it is preferable to use a conductive resin having an average particle diameter of 20 nm or less. If the average particle diameter 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 is supported on the surface of the single fibers, and easily peeled off by physical impact, High conductivity after repeated washing cannot be maintained. If the average particle size of the conductive polymer is 20 nm or less, it is supported on the surface of the single fiber and on the gap between the single fiber and the single fiber, hardly peels off by physical impact, and maintains high conductivity after repeated washing. it can. Here, the “main component” means to occupy a mass ratio of 50% or more of the constituent materials other than the fibers of the conductive fiber structure.

By using the conductive polymer and the olefin resin in combination, the compound in the conductive fiber structure can be brought into close contact with each other, and the conductive fiber structure can be formed more reliably. The olefin resin is preferably a nonpolar olefin resin from the viewpoint of 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 6 to less than 10, preferably 7 to 9. This SP value is a value determined by solubility.

The non-polar olefin resin preferably has an SP value of 6 to less than 10. A nonpolar olefin resin may be used independently and may use 2 or more types together.

Examples of the olefin resin include polyethylene, polypropylene, cycloolefin polymer (cyclic polyolefin), and polymers obtained by modifying them. In the fiber structure having conductivity, these may be used as an olefin resin, or those obtained by modifying polyvinyl chloride, polystyrene or the like with an olefin may be used as the olefin 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 fiber structure, a solvent may be added to form a treatment liquid, which may be used for processing. The solvent is not particularly limited. 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 ethers such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate, dipropylene glycol monoethyl ether acetate, etc .; 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, those provided with glycerol, physiological saline, or the like can be suitably used from the viewpoint of improving and stabilizing the conductivity, but are not limited thereto.

The conductive fiber structure of the present invention uses a precursor of the exemplified conductive resin or a treatment liquid such as a conductive resin solution, emulsion, or dispersion obtained by adding the above solvent to the conductive resin. The fiber structure can be supported by a known method such as dipping, coating, or spraying. The method for supporting the fiber structure is not particularly limited, but in order to support the conductive resin on the surface of the fiber and the gap between the single fiber and the single fiber, a conductive resin solution (emulsion, It is desirable to repeat immersion or spraying a plurality of times (including the dispersion). 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, as described above, it is preferable that the treatment agent containing the conductive resin is supported on the fiber structure and then heated. When heating, giving a thermal history not lower than the softening point of the component contained in the conductive resin and not higher than the decomposition temperature causes the component to melt and penetrate more into the single fiber gap and firmly adhere to it. It is preferable at the point which can provide the further washing resistance. The heating temperature is preferably 180 ° C. or lower, more preferably 80 ° C. to 180 ° C., and still more preferably 100 ° C. to 150 ° C. When the heating temperature is within the above range, the adhesion between the compounds constituting the conductive resin is good, and the fiber structure can be more reliably imparted with conductivity.

The antenna of the present invention preferably has a resin layer laminated on one side of a conductive fiber structure containing a conductive resin. By covering one surface of the conductive fiber structure with the resin layer, it is possible to greatly suppress the durability of the antenna, particularly the decrease in conductivity due to the dropping of the conductive resin due to washing. The type and shape of the polymer constituting the resin layer are not limited, but a waterproof and moisture-permeable layer having insulating properties is preferable in terms of required characteristics as an antenna.

Examples of waterproof and moisture-permeable layers include PTFE (polytetrafluoroethylene) porous membranes, non-porous membranes made of hydrophilic elastomers such as hydrophilic polyester resins and polyurethane resins, polyurethane resin microporous membranes, and other known membranes, films and laminates. In addition, a form in which a resin or the like is laminated by a coating or laminating method is exemplified, but the invention is not limited thereto. The waterproof / moisture permeable layer is preferably one in which a polyurethane resin microporous film having stretchability is laminated and adhered by lamination from the viewpoint of followability to a conductive fiber structure as a base material.

The performance of the antenna is related to the surface resistivity of the conductive fiber structure with respect to an alternating current having the same frequency as that used for communication, and the surface resistivity is preferably 0.01 to 0.1Ω / □. Although there is no restriction on the frequency used for communication, 100 MHz to 5 GHz is preferable from the viewpoint of communication performance such as communication distance, and 920 MHz and 2.45 GHz are particularly preferable from the viewpoint of easy availability of communication equipment. When the surface resistivity is greater than 0.1Ω / □, the current value flowing through the antenna is small, and stable communication is difficult.

The configuration of the antenna of the present invention includes a laminate of a conductor and a dielectric made of the conductive fiber structure processed into the shape of the antenna. There is no restriction | limiting in particular as said dielectric material, Fiber structures, such as a mesh, papermaking, a textile fabric, a knitted fabric, a nonwoven fabric, polymer films, such as a polyethylene terephthalate, and ceramic substrates, such as an alumina, can be used. However, generally, when the relative permittivity of the dielectric is high, loss when an alternating current flows through the antenna becomes large, and the frequency band becomes narrow, and stable communication becomes difficult. Therefore, the dielectric constant of the dielectric is preferably low. As the dielectric, an insulating base material is preferably used. Among the insulating base materials, since the fiber structure contains air in the gap between the fibers and has a low relative dielectric constant and a high flexibility, it can be suitably used for an antenna for smart textiles. For example, the relative dielectric constant of a polyethylene terephthalate film, which is a typical polymer film, is about 3.0, and the relative dielectric constant of polytetrafluoroethylene, which is a surface low dielectric polymer, is about 2.0. The relative dielectric constant of the nonwoven fabric is as low as 1.4. Below, the case where an insulating fiber structure is used for a dielectric material is mainly demonstrated. Note that the number of laminated layers is not particularly limited, and a two-layer structure composed of a conductive fiber structure and a conductor, a first conductor composed of a conductive fiber structure, a dielectric, and a conductive fiber. A three-layer structure composed of a second conductor composed of a structure, a first conductor composed of a conductive fiber structure, a first dielectric, a second conductor composed 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, a six-layer structure made of a third dielectric, and the like.

There are no particular restrictions on the type of antenna of the present invention. For example, a loop antenna (see FIG. 1A) used for communication in the HF (High Frequency) band, a spiral antenna, or communication in the UHF (Ultra High Frequency) band. Examples thereof 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.

In the loop antenna shown in FIG. 1A, an antenna 2 made of a conductive fiber structure is formed in a loop shape 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. 1B illustrates a meander-shaped antenna, but the shape is not limited as long as it has antenna performance, and a linear structure as shown in FIG. 2 may be used. Also, the width of the pattern is not particularly limited, and is designed from the viewpoint of antenna performance, pattern processability, and the like.

The patch antenna shown in FIGS. 1C and 1D is 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. And 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, or the circle shown in FIG. A replacement structure may be used. On the other hand, the second conductor 3B absorbs radio waves radiated from the first conductor 3A and prevents radio waves from being radiated to the back surface of the antenna. Note that 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 disposing a conductive fiber structure in the dielectric 2, a method of piercing a metal pin, Examples include a method using a metal button. As the metal button, a male button or a female button of a dot button is used. By engaging the male button disposed on the first conductor 3A and the second conductor 3B with the female button disposed 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 disposed on the first conductor 3A and the second conductor 3B and a male button is disposed on the dielectric 2 may be employed.

The method for processing the conductive fiber structure into a predetermined pattern is not particularly limited, and known techniques such as laser cutting, heat cutting, and die cutting can be used. Moreover, there is no restriction | limiting in particular as a method of bonding an electroconductive fiber structure to an insulating fiber structure, Well-known techniques, such as using sewing, the heat seal using an adhesive sheet, and a button, can be used. In addition, when attaching the antenna of the present invention to clothes, the antenna with the conductive fiber structure attached to the insulating fiber structure may be attached to the clothes, or the conductive fiber structure may be directly attached to the clothes. From the viewpoints of comfort, design, etc., it is preferable to apply the conductive fiber structure directly to the clothes.

By combining the antenna of the present invention and a semiconductor circuit having a communication function, it can be used as a wireless communication device. There is no restriction | limiting in particular as a wireless communication apparatus, An RFID tag, a beacon, a BlueTooth (trademark) communication apparatus etc. are mentioned. For example, by attaching these wireless communication devices to uniforms, it can be used for individual tracking of students, confirmation of attendance, etc. at school. Moreover, by attaching these wireless communication devices to hospitalized patients' inpatients, it can be used for inpatient individual tracking, individual authentication, and the like.

In the wireless communication apparatus of the present invention, the number of antennas and semiconductor circuits is not limited, and one antenna and one semiconductor circuit may be connected to each other, or two or more antennas may be connected to one semiconductor circuit. In particular, a blind spot of communication can be reduced by attaching a wireless communication device having two or more antennas to clothes. For example, by attaching the antenna of the present invention to the chest and back, stable communication is possible regardless of the body orientation with respect to the radio wave transmitter / receiver.

There are no particular restrictions on the connection method between the antenna and the semiconductor circuit. For example, metal wires, conductive yarns woven with metal wires, and the like are connected as wires, and connection using the conductive fiber structure according to the present invention can be mentioned. From the viewpoint of reducing the contact resistance by connecting the wiring between the antenna and the semiconductor circuit, the conductive fiber structure of the present invention is preferably used 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 communication distance can be increased by reducing the loss when a high-frequency signal is input from the semiconductor circuit 5 to the antenna.

It can also be used as a sensing device by combining the wireless communication device and various sensors. The type of sensor is not particularly limited. Sensors for acquiring environmental information such as temperature, humidity, illuminance, impact, and position, such as heart rate, electrocardiogram waveform, respiratory rate, blood pressure, brain potential, and myoelectric potential Examples include a bioelectrode for acquiring a biosignal, a biosensor for acquiring a blood glucose level, a cholesterol level, a hormone level, and the like. The wireless communication device and the sensor may be connected using wiring or may be connected by wireless communication. By using these sensing devices, health management in daily life, monitoring of workers in factories, etc., leisure management, health management during exercise, remote management of heart disease, hypertension, sleep apnea syndrome, etc. are possible However, it is not limited to these.

In addition, the wireless communication device combining the antenna of the present invention and a semiconductor circuit can be used as a reader / writer antenna for an RFID tag. For example, when an RFID system is used for detecting urination of hospitalized patients, it is necessary to install a reader / writer antenna on the bed. Since the hospital bed needs to be folded 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 hospitalized beds.

Hereinafter, the present invention will be described more specifically based on examples. In addition, this invention is not limited to the following Example.

(1) Method for producing conductive fiber structure 75T- of an alkali hot water soluble polyester comprising an island component of polyethylene terephthalate and a sea component of polyester as a polyester acid component of terephthalic acid and 5-sodium sulfoisophthalic acid. 100T-136F, which is a mixture of 112F (sea-island ratio 30%: 70%, 127 islands / F) nanofibers with a single fiber diameter of 700 nm and 22T-24F single-fiber diameter 22.85 μm polyethylene terephthalate high shrink yarn A circular knitted fabric was knitted with a smooth structure using the polyester nanofiber mixed yarn. Next, the fabric was dipped in a 3% by weight aqueous solution of sodium hydroxide (75 ° C., bath ratio 1:30) to remove easily soluble components, and a knitted fabric using mixed fibers of nanofibers and high shrinkage yarns was obtained. The density of the knitted fabric is 58 × 78 (lines / in), and the basis weight is 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, and the conductive polymer is applied by a known knife coating method. And heated to a temperature in the range of 120 ° C to 130 ° C. The conductive resin adhered amount of the obtained conductive structure was 12.3 g / m ² . In addition, it will be described later that the conductive resin exists substantially continuously in the fiber axis direction in the gap between the single fibers constituting the multifilament yarn. (3) Confirmed by the conductive resin-containing area ratio did. FIG. 10 is a cross-sectional photograph using the conductive resin impregnated area ratio of the conductive fiber structure for evaluation. FIG. 10 shows that the surface layer is impregnated with a low resistance, that is, a conductive resin from 30 μm. Furthermore, the surface resistivity of the manufactured conductive fiber structure was 0.045Ω / □.

(2) Fiber diameter The multifilament extracted from the fiber was embedded with epoxy resin, frozen with a Reichert FC-4E cryosectioning system, and cut with a Reichert-Nissei ultracut N equipped with a diamond knife. Thereafter, the cut surface was photographed with a VE-7800 scanning electron microscope (SEM) manufactured by Keyence Corporation at a magnification of 5000 times for nanofibers, 1000 times for microfibers, and 500 times for others. 150 ultrafine fibers randomly selected from the obtained photographs were extracted, and all circumscribed circle diameters (fiber diameters) were measured for the photographs using image processing software (WINROOF).

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

(4) Conductive polymer dispersed particle diameter Whether the conductive polymer dispersed particle diameter is less than 200 nm by filtering the conductive polymer dispersed in the dispersion with a Miniart 0.2 μm syringe filter manufactured by Sartorius. Was measured. It was confirmed that the dispersed particle diameter of the conductive polymer in “Denatron FB408B” used in (1) was less than 200 nm.

(5) Average particle diameter of conductive polymer (dynamic light scattering method)
The average particle diameter 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 volume resistance diameter was measured to obtain the particle diameter distribution, and the hydrodynamic diameter median diameter was calculated as the average particle diameter. The average particle diameter of the conductive polymer in “Denatron FB408B” used in (1) was 20 nm or less.

(6) Method for measuring electrical conductivity of conductive fiber structure The conductive fiber structure produced by the method described in (1) as a strip conductor is made of polytetrafluoroethylene having a thickness of 2 mm as 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. Excitation was performed from one coaxial cable of the half-wavelength microstrip line resonator A, a network analyzer was connected to the other coaxial cable, and an unloaded Q value (Q _A ) was measured. A half-wavelength microstrip line resonator B was prepared in the same manner as the half-wavelength microstrip line resonator A except that copper foil was used as the strip conductor, and the unloaded Q value (Q _B ) was measured. When Q _Sample is a Q value resulting from the loss of the conductive fiber structure strip and Q _Cu is a Q value resulting from the loss of the copper foil strip, 1 / Q _A −1 / Q _B = 1 / Q _Sample −1 / Q _Cu relation holds. Q _Cu was calculated from the surface resistivity of the copper foil, Q _Sample was calculated by applying the value to the above formula, and the surface resistivity and conductivity of the conductive fiber structure were calculated using the results. .

(7) Measuring method of reflection coefficient At 2.4 GHz shown in FIG. 5 using a conductive fiber structure or a conductive fiber structure made of silver-plated fibers and a non-woven fabric produced by the method described in (1). A radiating measurement antenna was produced. In addition, the dielectric 2 made of a nonwoven fabric is disposed between the first conductor 3A made of a conductive fiber structure and the second conductor 3B, and the first conductor 3A and the second conductor 3B Were electrically connected using a metal button 7. Using the coaxial cable terminal 6, the produced antenna was connected to a network analyzer (manufactured by Agilent Technologies, N5230C), and the reflection coefficient was measured.

(8) XZ plane radiation pattern measurement method As shown in FIG. 6, the measurement antenna prepared in (7) was installed on a turntable, and a network analyzer (N5230C, manufactured by Agilent Technologies) was used. 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, and the gain was measured. The radiation pattern was measured in an anechoic chamber using two types of horizontal polarization and vertical polarization.

(9) Conductive resin adhesion amount The conductive resin adhesion amount was measured by the mass change of the fiber structure which is the test cloth before and after application of the conductive resin dispersion in the standard state (20 ° C. × 65% RH). The calculation formula is as follows.
Conductive resin adhesion amount (g / m ² ) =
(Test cloth mass after processing (g) -Test mass before processing (g)) / Area coated with a dispersion of test cloth (m ² )

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

Comparative Example 1
Circular knitted fabrics were knitted using nickel / copper-plated fibers (manufactured by Tanimura Co., Ltd., MK-KTN260). The surface resistivity and conductivity measured by the method described in (6) are 0.050Ω / □ and 3.84 μS / m, respectively, and the reflection coefficient measured by the method described in (7) is −15.2 dB. there were. Moreover, the XZ plane radiation pattern measured by the method described in (8) is shown by the 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 XZ plane radiation pattern were measured in the same manner as in Example 1 except that the measurement antenna produced in (7) was attached to the human 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 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 increased by 6%.

DESCRIPTION OF SYMBOLS 1 Conductor 2 Dielectric 3A 1st conductor 3B 2nd conductor 4 Wiring 5 Semiconductor circuit 6 Coaxial cable terminal 7 Metal button

Claims

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 and / or a single fiber gap having a diameter of 100 nm to 1000 nm.
The conductive resin is carried in a gap between the single fibers constituting the fiber structure and the single fibers, and when the cross section in the thickness direction of the fiber structure is observed, the conductive resin exists in a region of 15 to 30 μm from the surface layer. The antenna according to claim 1, wherein the antenna has 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 contains a binder resin.
The antenna according to claim 4, wherein the binder resin is an olefin resin.
3. 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 substantially continuously present in the fiber axis direction in the 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 the conductive fiber structure has a surface resistivity of 0.01 to 0.1 Ω / □ measured at 920 MHz to 3 GHz.
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, and the second conductor made of the conductive fiber structure are laminated in this order, and the first conductor and the second conductor are laminated. The antenna of claim 9, wherein the bodies are 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 comprising 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 the antennas according to any one of claims 1 to 11, wherein at least one of them is attached to a different part from the other antennas.