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WO2019189245A1 - Gas adsorbent, gas sensor, and method for manufacturing gas adsorbent - Google Patents

Gas adsorbent, gas sensor, and method for manufacturing gas adsorbent Download PDF

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Publication number
WO2019189245A1
WO2019189245A1 PCT/JP2019/012979 JP2019012979W WO2019189245A1 WO 2019189245 A1 WO2019189245 A1 WO 2019189245A1 JP 2019012979 W JP2019012979 W JP 2019012979W WO 2019189245 A1 WO2019189245 A1 WO 2019189245A1
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WO
WIPO (PCT)
Prior art keywords
gas
gas adsorbent
organic material
molded body
conductive particles
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Application number
PCT/JP2019/012979
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French (fr)
Japanese (ja)
Inventor
篤 守法
厚夫 中尾
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パナソニック株式会社
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Publication of WO2019189245A1 publication Critical patent/WO2019189245A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/20—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising free carbon; comprising carbon obtained by carbonising processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
    • G01N27/04—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance
    • G01N27/12—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating resistance of a solid body in dependence upon absorption of a fluid; of a solid body in dependence upon reaction with a fluid, for detecting components in the fluid

Definitions

  • the present disclosure relates to a gas adsorber, a gas sensor, and a method for manufacturing the gas adsorber, and more specifically, includes a gas adsorber including an organic material and conductive particles, a gas sensor including the gas adsorber, and an organic material and conductive particles.
  • the present invention relates to a method for manufacturing a gas adsorbent.
  • a gas sensor including a gas adsorbing organic material and conductive particles dispersed in the organic material.
  • an electrically insulating substrate including a pair of conductive wires arranged in a circular shape so as to be parallel to each other, a chemically sensitive polymer in contact with the pair of conductive wires, and dispersed in the chemically sensitive polymer
  • a chemi-resistor is disclosed that includes carbon particles that perform.
  • a chemically sensitive polymer adsorbs a volatile organic compound or the like in a gas, a change in electric resistance value occurs.
  • volatile organic compounds in the gas can be detected based on a change in the electrical resistance value of the chemi-resistor.
  • the change in electrical resistance value that occurs when exposed to gas is less likely to be disturbed, and the change in electrical resistance value occurs when exposed to gas.
  • An easy-to-use gas adsorber, a gas sensor including the gas adsorber, and a method for manufacturing the gas adsorber are provided.
  • the gas adsorbent according to one embodiment of the present disclosure includes conductive particles and an organic material that covers at least a part of the conductive particles.
  • the gas adsorbent is porous.
  • a gas sensor includes the gas adsorber and an electrode that is electrically connected to the gas adsorber.
  • a method for producing a gas adsorbent according to an aspect of the present disclosure includes preparing a mixed liquid containing an organic material, conductive particles, and a solvent, forming a molded body from the mixed liquid, Volatilizing the solvent and thermally decomposing part of the organic material in the molded body.
  • FIG. 1A is a schematic cross-sectional view showing a molded body produced in the manufacturing process of a gas adsorbent according to an embodiment of the present disclosure
  • FIG. 1B is a schematic view showing a state after the solvent is volatilized from the molded body shown in FIG. 1A.
  • Sectional drawing and FIG. 1C are schematic sectional drawings which show the gas adsorber in one Embodiment of this invention.
  • 2A, 2B, 2C, and 2D are transmission electron micrographs of cut surfaces of Sample 1, Sample 2, Sample 3, and Sample 4, respectively.
  • 3A, FIG. 3B, FIG. 3C, and FIG. 3D are transmission electron micrographs of cut surfaces of Sample 1, Sample 2, Sample 3, and Sample 4, respectively.
  • FIG. 1A is a schematic cross-sectional view showing a molded body produced in the manufacturing process of a gas adsorbent according to an embodiment of the present disclosure
  • FIG. 1B is a schematic view showing a state after the solvent is volatilized from the molded
  • FIG. 4 is a plan view schematically showing the configuration of a test gas sensor used in the evaluation of responsiveness and noise in Examples.
  • FIG. 5 is a graph showing the results of evaluation of responsiveness and noise in the example, in which the horizontal axis represents the elapsed time, and the vertical axis represents the normalized electric resistance values of Samples 1 and 2.
  • FIG. 6 is a plan view schematically illustrating the configuration of a test gas sensor used in the evaluation of responsiveness and noise in Examples.
  • FIG. 7 is a graph showing the results of sensitivity evaluation in Examples, in which the horizontal axis represents elapsed time and the vertical axis represents normalized electrical resistance values of Samples 2 and 4.
  • a change in electric resistance value occurs in the gas adsorber.
  • One cause of the change in the electrical resistance value is presumed that the distance between the conductive particles in the gas adsorbent changes due to the organic material adsorbing the chemical substance and expanding.
  • a chemical substance in the gas can be detected using the change in the electric resistance value of the gas adsorbent. That is, a chemical substance in the gas can be detected using a gas sensor including a gas adsorbent.
  • the inventors have developed a gas adsorbent that is less likely to be disturbed in the change in electrical resistance value when exposed to a gas containing a chemical substance and that is likely to change in electrical resistance value when exposed to a gas. Therefore, as a result of earnest research, the present disclosure has been completed.
  • FIGS. 1A, 1B, and 1C An embodiment of the present disclosure will be described with reference to FIGS. 1A, 1B, and 1C.
  • the manufacturing method of the gas adsorbent 1 according to the present embodiment includes the following steps.
  • the formed body 4 is formed from the mixed solution.
  • the solvent in the molded body 4 is volatilized.
  • the gas adsorbent 1 includes conductive particles 2 and an organic material 3 that covers at least a part of the conductive particles 2.
  • the gas adsorbent 1 is porous.
  • the gas adsorbent 1 can be manufactured by the above manufacturing method.
  • the gas adsorbent 1 When the gas adsorbent 1 according to the present embodiment adsorbs a chemical substance in the gas by being exposed to the gas, the electric resistance value changes. In the present embodiment, when the gas adsorbent 1 is exposed to gas and adsorbs a chemical substance in the gas, the gas adsorbent 1 is likely to change in electric resistance value. Furthermore, in this embodiment, the change in the electric resistance value of the gas adsorbent 1 is not easily disturbed.
  • the gas sensor 10 includes the gas adsorbent 1 described above and an electrode 5 in contact with the gas adsorbent 1. If this gas sensor 10 is used, the chemical substance in gas can be detected accurately.
  • a mixed solution containing an organic material 3, conductive particles 2, and a solvent is prepared.
  • the organic compound preferably has gas adsorbability.
  • Gas adsorbability refers to the property of adsorbing chemical substances contained in gas when exposed to gas.
  • chemical substances include volatile organic compounds and inorganic compounds.
  • volatile organic compounds include ketones, amines, alcohols, aromatic hydrocarbons, aldehydes, esters, organic acids, methyl mercaptans, and disulfides.
  • inorganic compounds include hydrogen sulfide, sulfur dioxide, and carbon disulfide.
  • the organic material 3 preferably has a property of adsorbing at least one kind of chemical substance. It can be judged based on technical common sense that the organic material 3 has gas adsorbability.
  • the organic material 3 when the organic material 3 is exposed to gas and then analyzed by a gas chromatograph mass spectrometer, if a chemical substance derived from gas is detected, the organic material 3 is determined to have gas adsorbability. Is done.
  • the organic material 3 preferably has a property of adsorbing at least one volatile organic compound.
  • the organic material 3 is selected according to the type of chemical substance to be adsorbed by the gas adsorbent 1 and the type of conductive particles 2 in the gas adsorbent 1.
  • the organic material 3 includes, for example, at least one material selected from the group consisting of a polymer and a low molecule.
  • the organic material 3 particularly preferably contains a polymer. When the organic material 3 contains a polymer, the gas adsorbent 1 can have heat resistance.
  • a preferable example of the organic material 3 includes a material that is commercially available as a stationary phase of a column in a gas chromatograph. More specifically, the organic material 3 is, for example, at least one material selected from the group consisting of polyalkylene glycols, polyesters, silicones, glycerols, nitriles, dicarboxylic acid monoesters, and aliphatic amines. including. In this case, the organic material 3 can easily adsorb chemical substances in the gas, particularly volatile organic compounds.
  • Polyalkylene glycols include, for example, polyethylene glycol (heat resistant temperature: 170 ° C.).
  • Polyesters include, for example, at least one material selected from the group consisting of poly (diethylene glycol adipate) and poly (ethylene succinate).
  • the silicones include, for example, at least one material selected from the group consisting of dimethylsilicone, phenylmethylsilicone, trifluoropropylmethylsilicone, and cyanosilicone (heat-resistant temperature 275 ° C.).
  • Glycerols include, for example, diglycerol (heat resistant temperature 150 ° C.).
  • Nitriles are selected from the group consisting of, for example, N, N-bis (2-cyanoethyl) formamide (heat resistant temperature 125 ° C.) and 1,2,3-tris (2-cyanoethoxy) propane (heat resistant temperature 150 ° C.).
  • the dicarboxylic acid monoesters include, for example, at least one material selected from the group consisting of nitroterephthalic acid-modified polyethylene glycol (heat resistant temperature 275 ° C.) and diethylene glycol succinate (heat resistant temperature 225 ° C.).
  • Aliphatic amines include, for example, tetrahydroxyethylethylenediamine (heat resistant temperature 125 ° C.).
  • the conductive particles 2 include, for example, at least one material selected from the group consisting of carbon materials, conductive polymers, metals, metal oxides, semiconductors, superconductors, and complex compounds.
  • the carbon material includes, for example, at least one material selected from the group consisting of carbon black, graphite, coke, carbon nanotube, graphene, and fullerene.
  • the conductive polymer includes, for example, at least one material selected from the group consisting of polyaniline, polythiophene, polypyrrole, and polyacetylene.
  • the metal includes, for example, at least one material selected from the group consisting of silver, gold, copper, platinum, and aluminum.
  • the metal oxide includes, for example, at least one material selected from the group consisting of indium oxide, tin oxide, tungsten oxide, zinc oxide, and titanium oxide.
  • the semiconductor includes, for example, at least one material selected from the group consisting of silicon, gallium arsenide, indium phosphide, and molybdenum sulfide.
  • the superconductor includes, for example, at least one material selected from the group consisting of YBa 2 Cu 3 O 7 and Tl 2 Ba 2 Ca 2 Cu 3 O 10 .
  • Complex compounds include, for example, complex compounds of tetramethylparaphenylenediamine and chloranil, complex compounds of tetracyanoquinodimethane and alkali metals, complex compounds of tetrathiafulvalene and halogen, complex compounds of iridium and halocarbonyl compounds. And at least one material selected from the group consisting of tetracyanoplatinum.
  • the conductive particles 2 preferably contain a carbon material. It is particularly preferable that the conductive particles 2 contain carbon black. When the conductive particles 2 contain a carbon material, particularly carbon black, the electric resistance value of the gas adsorbent 1 is particularly likely to change when exposed to gas.
  • the average particle diameter of the conductive particles 2 is, for example, 10 nm or more and 300 nm or less. In this case, it is easy to make the gas adsorbent 1 porous when the gas adsorbent 1 is manufactured.
  • the average particle diameter of the conductive particles 2 is an arithmetic average value based on the number of particle diameters obtained from an electron micrograph of the conductive particles 2. Specifically, the area of each of the conductive particles 2 appearing in the electron micrograph is derived by performing image processing on the electron micrograph, and from the area of the conductive particle 2, each of the conductive particles 2 is converted into a perfect circle. The average particle diameter is obtained by calculating the diameter and obtaining the average value of the diameters.
  • the solvent is not limited as long as the organic material 3 can be dissolved or dispersed and can be volatilized from the molded body 4.
  • the solvent contains at least one component selected from the group consisting of dimethyl sulfoxide, dimethylformamide, toluene, chloroform, acetone, acetonitrile, methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, and butyl acetate, for example.
  • a molded body 4 is formed from the mixed solution.
  • the molded body 4 is preferably in the form of a film.
  • the film-like gas adsorbent 1 can be manufactured.
  • seat, a layer, etc. may be contained in a film
  • the molded body 4 can be formed by applying the mixed liquid by a method such as an inkjet method or a dispensing method.
  • the thickness of the molded body 4 is, for example, 0.1 ⁇ m or more and 10 ⁇ m or less.
  • the molded body 4 has a structure in which conductive particles 2 are dispersed in a liquid 7 containing a solvent and an organic material 3.
  • the solvent in the molded body 4 is volatilized.
  • the solvent can be volatilized from the molded body 4 by subjecting the molded body 4 to a heat treatment (hereinafter also referred to as a first heat treatment).
  • a first heat treatment By disposing the molded body 4 under reduced pressure, the solvent can be volatilized from the molded body 4.
  • the solvent can be volatilized from the molded body 4 by subjecting the molded body 4 to a first heat treatment under reduced pressure.
  • the temperature of the first heat treatment is appropriately set so as to promote the volatilization of the solvent according to the type of the solvent.
  • the temperature of 1st heat processing is 30 degreeC or more and 90 degrees C or less, for example.
  • the temperature of the first heat treatment is designed so that the organic material 3 is not thermally decomposed or hardly thermally decomposes. Therefore, for example, the temperature of the first heat treatment is preferably less than 30 ° C. lower than the heat resistant temperature of the organic material 3.
  • the time for the first heat treatment is preferably designed so that all or most of the solvent in the molded body 4 is volatilized by the first heat treatment. The time for the first heat treatment is, for example, not less than 10 minutes and not more than 60 minutes.
  • the conductive particles 2 in the molded body 4 move, the interval between adjacent particles becomes smaller, and the conductive particles 2 are connected. Is easily formed. It is surmised that this is because the volatilization of the solvent causes the flow, shape change, volume change, etc. of the molded body 4 to promote the movement of the conductive particles 2.
  • the solvent is volatilized by subjecting the molded body 4 to the first heat treatment, the movement of the conductive particles 2 in the molded body 4 is promoted, and a structure in which the conductive particles 2 are continuous is particularly easily formed.
  • a part of the organic material 3 in the molded body 4 is thermally decomposed. That is, the remaining part of the organic material 3 that has not been thermally decomposed is left in the molded body 4.
  • a second heat treatment it is preferable to heat-treat the molded body 4 (hereinafter also referred to as a second heat treatment).
  • the temperature of the second heat treatment is appropriately designed so that the thermal decomposition of the organic material 3 can be promoted.
  • the temperature of the second heat treatment is, for example, not less than a temperature 30 ° C. lower than the heat resistant temperature of the organic material 3 and not higher than 30 ° C. higher than the heat resistant temperature.
  • the time of the second heat treatment is designed so that the thermal decomposition of a part of the organic material 3 in the molded body 4 is completed by the second heat treatment, that is, the remainder of the organic material 3 remains without being thermally decomposed. It is preferred that The time for the second heat treatment is, for example, not less than 10 minutes and not more than 120 minutes.
  • the thermally decomposed organic material 3 is removed from the molded body 4, and a void 11 is generated.
  • the remaining part of the organic material 3 that remains in the molded body 4 without being thermally decomposed is easily disposed so as to cling to the conductive particles 2.
  • the gas adsorbent 1 is obtained by thermally decomposing a part of the organic material 3 in this manner.
  • the gas adsorbent 1 includes conductive particles 2 and an organic material 3 that covers at least a part of the conductive particles 2.
  • the gas adsorbent 1 is porous by having a void 11 formed by removing a part of the organic material 3.
  • the step of volatilizing the solvent in the molded body 4 and the step of thermally decomposing a part of the organic material 3 in the molded body 4 may be completely separated in time series or completely separated. You don't have to. That is, in the step of volatilizing the solvent in the molded body 4, the thermal decomposition of a part of the organic material 3 may proceed incompletely. Further, in the step of thermally decomposing a part of the organic material 3 in the molded body 4, a solvent may remain in the molded body 4 and the volatilization of the solvent may proceed. However, in the step of volatilizing the solvent in the molded body 4, it is preferable that the thermal decomposition of a part of the organic material 3 does not proceed.
  • volatilizing the solvent in the molded body 4 it is preferable to volatilize the solvent in the molded body 4 by applying a first heat treatment to the molded body 4. Furthermore, in thermally decomposing a part of the organic material 3 in the molded body 4, the molded body 4 is subjected to a second heat treatment at a higher temperature than in the case of the first heat treatment. It is preferable to thermally decompose a part. In this case, by adjusting the temperature of the first heat treatment and the temperature of the second heat treatment, when the solvent is volatilized in the first heat treatment, thermal decomposition of the organic material 3 does not proceed or thermal decomposition proceeds. In the second heat treatment, it is easy to efficiently thermally decompose a part of the organic material 3.
  • the gas adsorbent 1 includes the conductive particles 2 and the organic material 3 that covers at least a part of the conductive particles 2.
  • the gas adsorbent 1 is porous.
  • the gas adsorbent 1 is made porous by having the voids 11 formed by thermally decomposing and removing a part of the organic material 3.
  • the gas adsorbent 1 may be made porous by having voids 11 formed by a mechanism different from this.
  • the voids 11 may be formed at locations where the beads were present by allowing the molded body 4 to contain beads and then removing the beads from the molded body 4.
  • beads can be contained in the molded body 4 by forming the molded body from the mixed liquid by including beads in the mixed liquid for forming the molded body 4 described above.
  • beads are easily decomposed or volatilized by heating, are easily decomposed or volatilized by receiving light such as ultraviolet rays, or are easily decomposed or volatilized by reacting with a highly reactive gas such as ozone.
  • a highly reactive gas such as ozone.
  • the beads can be removed from the molded body 4 by forming the voids 11 by heating the beads, irradiating the beads with light, or reacting the beads with a highly reactive gas.
  • the beads may be removed from the molded body 4 by an appropriate method according to the characteristics of the beads.
  • the beads can be made from an appropriate organic material according to the properties required for the beads, for example.
  • the particle diameter of the beads is selected according to the size desired for the void 11 and is, for example, not less than 10 nm and not more than 1 ⁇ m.
  • the gas adsorbent 1 may be made porous by having a plurality of types of voids 11 formed by different mechanisms.
  • the amount of the organic material 3, the conductive particles 2, and the solvent in the mixed solution is appropriately set. For example, by adjusting the amount of the solvent and the amount of the conductive particles 2 in the mixed solution, it is possible to control the occurrence of a series of the conductive particles 2 when the solvent is volatilized from the molded body 4. Further, for example, by adjusting the amount of the organic material 3 in the mixed solution, the degree of the void 11 in the gas adsorbent 1, that is, the porosity can be controlled.
  • the amount of the organic material 3 in the mixed solution is, for example, 1 mg or more and 30 mg or less with respect to 1 ml of the solvent.
  • the amount of the conductive particles 2 in the mixture is, for example, 1 mg or more and 30 mg or less with respect to 1 ml of the solvent.
  • the gas adsorbent 1 is preferably in the form of a film. That is, the gas adsorbent 1 is preferably a porous film. In this case, since the specific surface area of the gas adsorbent 1 is increased, the gas adsorbent 1 can easily adsorb the chemical substance in the gas.
  • the thickness of the gas adsorbent 1 is, for example, not less than 0.1 ⁇ m and not more than 10 ⁇ m.
  • the organic material 3 adsorbs a chemical substance in the gas, and the electric resistance value of the gas adsorbent 1 changes accordingly.
  • a change in the electrical resistance value when the gas adsorbent 1 is exposed to gas is likely to occur quickly.
  • the degree of change in the electrical resistance value tends to increase.
  • the gas adsorbent 1 can adsorb chemical substances in the gas efficiently because the gas adsorbent 1 is porous.
  • another reason is that a structure in which the conductive particles 2 are continuous in the gas adsorbent 1 is formed, and this structure serves as a current path. That is, when the organic material 3 between the adjacent conductive particles 2 in the structure in which the conductive particles 2 are continuous adsorbs gas and expands, the interval between the conductive particles 2 constituting the current path is likely to change. Therefore, it is assumed that the electrical resistance value is likely to change.
  • the change in the electric resistance value of the gas adsorbent 1 is hardly disturbed. That is, the electrical resistance value is likely to change smoothly.
  • the reason is assumed to be as follows.
  • the change in the electrical resistance value of the gas adsorbent containing the organic material and the conductive particles dispersed in the organic material is disturbed because the conductive particles move in the organic material due to Brownian motion, etc. This is presumably because the positional relationship between the sex particles is likely to change.
  • the gas adsorbent 1 according to the present embodiment includes the organic material 3 and the conductive particles 2 as shown in FIG. 1C, the organic material 3 covers at least a part of the conductive particles 2.
  • the conductive particles 2 are difficult to move in the organic material 3. Therefore, the positional relationship between the conductive particles 2 is hardly changed in the gas adsorbent 1. Therefore, when the electric resistance value of the gas adsorbent 1 changes, it is considered that the change in the electric resistance value is less likely to be disturbed.
  • the porosity of the gas adsorbent 1 is preferably 10% or more.
  • the porosity is defined as the area ratio of the void 11 in the cut surface when the gas adsorbent 1 is cut. The area of the gap 11 in the cut surface can be confirmed by observing the cut surface with an electron microscope.
  • the porosity of the gas adsorbent 1 is 10% or more, when the gas adsorbent 1 is exposed to gas and adsorbs a chemical substance, the electrical resistance value is particularly likely to change. This is presumed to be because the chemical substance in the gas is efficiently adsorbed to the gas adsorbent 1 because the gas easily enters the gap 11.
  • the porosity is more preferably 15% or more. Further, the porosity is preferably 30% or less, and more preferably 25% or less.
  • the gas sensor 10 provided with the gas adsorbent 1 will be described.
  • the gas sensor 10 includes a gas adsorber 1 and an electrode 5 that is electrically connected to the gas adsorber 1.
  • the gas adsorbent 1 adsorbs the chemical substance, whereby the electric resistance value of the gas adsorbent 1 changes.
  • a chemical substance can be detected based on the change in the electrical resistance value.
  • the change in the electric resistance value generated in the gas adsorbent 1 is not easily disturbed, and the electric resistance value is likely to change when exposed to gas. For this reason, the chemical substance in gas can be detected accurately by using the gas sensor 10.
  • the gas sensor 10 includes a gas adsorbent 1 and an electrode 5.
  • the electrode 5 includes a first electrode 51 and a second electrode 52.
  • the gas sensor 10 further includes a substrate 6.
  • the base material 6 has electrical insulation.
  • the substrate 6 has one surface (hereinafter referred to as a support surface 61), and the first electrode 51, the second electrode 52, and the gas adsorbent 1 are disposed on the support surface 61.
  • the substrate 6 has, for example, a plate shape having a thickness in a direction orthogonal to the support surface 61.
  • the first electrode 51 and the second electrode 52 are arranged at an interval in a direction orthogonal to the direction in which the support surface 61 faces.
  • the gas adsorbent 1 is disposed on the support surface 61 of the substrate 6 and covers the first electrode 51 and the second electrode 52. Thereby, the gas adsorbent 1 and each of the first electrode 51 and the second electrode 52 are in contact with each other.
  • the electrical connection between the gas adsorber 1 and each of the first electrode 51 and the second electrode 52 may be achieved by any structure.
  • the gas adsorbent 1 may be in contact with the entire first electrode 51 or may be in contact with a part thereof. Further, the gas adsorbent 1 may be in contact with the entire second electrode 52 or may be in contact with a part thereof.
  • the electrical resistance value of the gas adsorbent 1 can be measured.
  • a chemical substance can be detected from the electric resistance value.
  • FIG. You may detect a chemical substance from the voltage drop amount between the 1st electrode 51 and the 2nd electrode 52 in the state which sent the constant current to the gas adsorption body 1.
  • the chemical substance may be detected based on an index that changes in accordance with a change in the electric resistance value of the gas adsorbent 1.
  • the first electrode 51 and the second electrode 52 are provided on the support surface 61 of the base 6, and then the molded body 4 is formed on the support surface 61 from the mixed liquid as described above. To do.
  • the molded body 4 is formed so as to cover the first electrode 51 and the second electrode 52. Subsequently, the gas adsorbent 1 is produced from the molded body 4 as described above.
  • test method and test results related to this embodiment will be presented. Note that the following test methods and test results do not limit the configuration of the present embodiment.
  • Carbon black having an average particle size of 44 nm was prepared as the conductive particles 2.
  • Dimethylformamide was prepared as a solvent.
  • Polyethylene glycol was prepared as the organic material 3.
  • the film-like molded body 4 was formed by applying the mixed solution by an inkjet method.
  • the molded body 4 was heat treated at 50 ° C. for 20 minutes to volatilize the solvent from the molded body 4. Thereby, Sample 1 was obtained.
  • the film-like molded body 4 was formed by applying the mixed solution by an inkjet method.
  • the solvent was volatilized from the molded body 4 by subjecting the molded body 4 to a heat treatment (first heat treatment) at 50 ° C. for 20 minutes.
  • a part of the organic material 3 in the molded body 4 was thermally decomposed by subjecting the molded body 4 to a heat treatment (second heat treatment) at 170 ° C. for 60 minutes. Thereby, Sample 2 was obtained.
  • the mixture was applied by an ink jet method to form a film-like molded body 4.
  • the molded body 4 was heat treated at 50 ° C. for 20 minutes to volatilize the solvent from the molded body 4. As a result, Sample 3 was obtained.
  • Sample 4 By adding the conductive particles 2 and the organic material 3 to the solvent and stirring, a mixed liquid containing the conductive particles 2 at a concentration of 2.5 mg / ml and the organic material 3 at a concentration of 17.5 mg / ml Prepared.
  • the film-like molded body 4 was formed by applying the mixed solution by an inkjet method.
  • the solvent was volatilized from the molded body 4 by subjecting the molded body 4 to a heat treatment (first heat treatment) at 50 ° C. for 20 minutes.
  • a part of the organic material 3 in the molded body 4 was thermally decomposed by subjecting the molded body 4 to a heat treatment (second heat treatment) at 170 ° C. for 60 minutes.
  • Sample 4 was obtained.
  • sample 1 was 7.56%
  • the porosity of sample 2 was 14.88%
  • the porosity of sample 3 was 3.59%
  • the porosity of sample 4 was 26.29%.
  • sample 1 and sample 3 have few voids 11 and are not recognized to be porous, whereas sample 2 and sample 4 are recognized to be porous.
  • sample 1 and sample 2 have the same ratio of conductive particles 2 and organic material 3 in the mixed liquid as a raw material, but sample 2 is porous by the second heat treatment in the manufacturing process. In contrast, the manufacturing process of Sample 1 does not include the second heat treatment, and Sample 1 is not made porous.
  • the outline of the structure of the test gas sensor 10 is as shown in FIG.
  • a first electrode 51 arranged in a ring shape and a second electrode 52 arranged in a ring shape are provided concentrically on the electrically insulating base 6.
  • an electrically insulating film (insulating film 9) was provided on the substrate 6 so as to cover the first electrode 51 and the second electrode 52.
  • eight first openings 71 having a diameter of 5 ⁇ m were provided on the circumference of a virtual circle having a diameter D1 of 600 ⁇ m so as to communicate with the first electrode 51.
  • Eight second openings 72 having a diameter of 5 ⁇ m were provided on the circumference of a virtual circle having a diameter D2 of 800 ⁇ m so as to communicate with the second electrode 52. Furthermore, each sample as the gas adsorbent 1 was provided on the base material 6 so as to cover the insulating film 9 so as to have a thickness of 1 ⁇ m. Therefore, the gas adsorbent 1 comes into contact with each of the first electrode 51 and the second electrode 52 through the first opening 71 and the second opening 72.
  • the diameter D3 of the gas adsorbent 1 shown in FIG. 4 is 900 ⁇ m.
  • the gas sensor 10 includes a first terminal 81 that extends from one end of the first electrode 51 and protrudes outside the gas adsorbent 1, and a first terminal that extends from one end of the second electrode 52 and protrudes outside the gas adsorbent 1. Two terminals 82 were provided.
  • the gas sensor 10 was placed in a nitrogen stream, and then nonanal was mixed into the stream for about 15 seconds. In this process, the current flowing between the first terminal 81 and the second terminal 82 was measured, and the electric resistance value of each sample as the gas adsorbent 1 was calculated from the result.
  • FIG. 5 shows the change over time in the electrical resistance value of each sample.
  • the horizontal axis represents the elapsed time, and nonanal was mixed in the airflow from the time point of about 30 seconds to the time point of about 45 seconds on the scale of the horizontal axis.
  • the vertical axis represents the normalized electrical resistance value of each sample.
  • the standardized electrical resistance value was defined as 1 as a result of measuring the electrical resistance value of each sample in a nitrogen stream in advance.
  • the electrical resistance value of sample 2 quickly increased when nonanal was mixed in the air stream, and rapidly decreased when nonanal disappeared from the air stream. Moreover, the change in electrical resistance value was smooth, and no significant disturbance was observed.
  • the electrical resistance value of sample 1 gradually increased from the time when nonanal was mixed in the air stream, and gradually decreased when nonanal disappeared from the air stream. In addition, a slight vertical movement was observed in the change in the electrical resistance value. For this reason, it can be said that the gas sensor 10 including the sample 2 has better responsiveness and less noise than the gas sensor 10 including the sample 1.
  • the outline of the structure of the test gas sensor 10 is as shown in FIG.
  • the first electrode 51 and the second electrode 52 are provided on the electrically insulating base 6 so as to constitute a comb-shaped electrode system.
  • the dimension L1 of the comb electrode system in the direction along the comb-shaped teeth is 520 ⁇ m, and the dimension L2 in the direction perpendicular to the comb-shaped teeth is 500 ⁇ m.
  • an electrically insulating film (insulating film 9) was provided on the substrate 6 so as to cover the first electrode 51 and the second electrode 52.
  • a strip-shaped opening 70 having a width of 5 ⁇ m shown in FIG. 6 is provided so as to overlap the first electrode 51 and the second electrode 52.
  • the dimension L3 between the centers of the openings 70 shown in FIG. 6 is 60 ⁇ m. Furthermore, each sample as the gas adsorbent 1 was provided on the base material 6 so as to cover the insulating film 9 so as to have a thickness of 1 ⁇ m. Therefore, the gas adsorbent 1 comes into contact with the first electrode 51 and the second electrode 52 through the opening 70.
  • the diameter D3 of the gas adsorbent 1 shown in FIG. 6 is 900 ⁇ m.
  • the gas sensor 10 includes a first terminal 81 that extends from one end of the first electrode 51 and protrudes outside the gas adsorbent 1, and a first terminal that extends from one end of the second electrode 52 and protrudes outside the gas adsorbent 1. Two terminals 82 were provided.
  • the gas sensor 10 was placed in a nitrogen stream, and then nonanal was mixed into the stream for about 15 seconds. In this process, the current flowing between the first terminal 81 and the second terminal 82 was measured, and the electric resistance value of each sample as the gas adsorbent 1 was calculated from the result.
  • FIG. 7 shows the change over time in the electrical resistance value of each sample.
  • the horizontal axis represents the elapsed time, and nonanal was mixed in the airflow from the time point of about 30 seconds to the time point of about 45 seconds on the scale of the horizontal axis.
  • the vertical axis represents the normalized electrical resistance value of each sample.
  • the standardized electrical resistance value was defined as 1 as a result of measuring the electrical resistance value of each sample in a nitrogen stream in advance.
  • the electrical resistance values of Sample 2 and Sample 4 both increased when nonanal was mixed in the air stream and decreased when nonanal disappeared from the air stream. Further, the degree of change in the electric resistance value of Sample 4 was larger than the degree of change in the electric resistance value of Sample 2. For this reason, it can be said that the gas sensor 10 including the sample 4 that is more porous than the sample 2 has higher sensitivity than the gas sensor 10 including the sample 2.
  • the gas adsorbent (1) covers the conductive particles (2) and at least a part of the conductive particles (2).
  • the gas adsorbent (1) is porous.
  • the organic material (3) and the conductive particles (2) are included, the electrical resistance value is likely to change when exposed to gas, and the electrical resistance value changes when the electrical resistance value changes.
  • a gas adsorbent (1) is obtained in which the resistance value is less likely to be disturbed.
  • the gas adsorbent (1) in the first aspect, is a film.
  • the specific surface area of the gas adsorbent (1) can be increased, and the gas adsorbent (1) can easily adsorb the chemical substance in the gas.
  • the conductive particles (2) include a carbon material.
  • the electrical resistance value of the gas adsorbent (1) is particularly likely to change when exposed to gas.
  • the organic material (3) includes a polymer.
  • the gas adsorbent (1) can have heat resistance.
  • the porosity of the gas adsorbent (1) is 10% or more.
  • the electric resistance value of the gas adsorber (1) is particularly likely to change.
  • a gas sensor (10) includes a gas adsorbent (1) according to any one of the first to fifth aspects, and an electrode electrically connected to the gas adsorbent (1) ( 5).
  • the sixth aspect includes the gas adsorbing organic material (3) and the conductive particles (2), and the electrical resistance value is likely to change when exposed to the gas, and the electrical resistance value changes.
  • the gas sensor (10) including the gas adsorbent (1) that is less likely to cause a disturbance in the electric resistance value is obtained.
  • the manufacturing method of the gas adsorbent (1) according to the seventh aspect of the present disclosure includes preparing a mixed solution containing the organic material (3), the conductive particles (2), and a solvent, and molding from the mixed solution. Forming a body (4), volatilizing a solvent in the molded body (4), and thermally decomposing a part of the organic material (3) in the molded body (4).
  • the electrical resistance value is likely to change when exposed to the gas, and the electrical resistance value changes when the electrical resistance value changes.
  • a gas adsorbent (1) in which the resistance value is hardly disturbed can be manufactured.
  • the gas adsorbent (1) is formed into a film by forming the molded body (4) into a film. Form.
  • the specific surface area of the gas adsorber (1) can be increased, and the gas adsorber (1) can easily adsorb the chemical substance in the gas.
  • the first heat treatment is performed on the molded body (4), whereby the molded body (4) A part of the organic material (3) in the molded body (4) is thermally decomposed by volatilizing the solvent and subjecting the molded body (4) to a second heat treatment at a temperature higher than that of the first heat treatment.
  • a part of the organic material (3) in the molded body (4) is particularly easily decomposed, so that the void 11 is particularly easily formed.
  • the conductive particles (2) include a carbon material.
  • a change in the electric resistance value of the gas adsorbent (1) is particularly likely to occur when exposed to gas.
  • the organic material (3) includes a polymer.
  • the gas adsorbent (1) can have heat resistance.

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Abstract

The present disclosure provides a gas adsorbent (1) including an organic material (3) and conductive particles (2), wherein when the gas adsorbent is exposed to a gas, disorder in variation of resistance value is not easily caused, and when the gas adsorbent is exposed to a gas, variation of resistance value is easily generated. The gas adsorbent (1) includes conductive particles (2) and an organic material (3) that covers at least a portion of the conductive particles (2). The gas adsorbent (1) is porous.

Description

ガス吸着体、ガスセンサ及びガス吸着体の製造方法Gas adsorbent, gas sensor, and method of manufacturing gas adsorbent
　本開示は、ガス吸着体、ガスセンサ及びガス吸着体の製造方法に関し、詳しくは有機材料と導電性粒子とを含むガス吸着体、ガス吸着体を備えるガスセンサ、及び有機材料と導電性粒子とを含むガス吸着体の製造方法に関する。 The present disclosure relates to a gas adsorber, a gas sensor, and a method for manufacturing the gas adsorber, and more specifically, includes a gas adsorber including an organic material and conductive particles, a gas sensor including the gas adsorber, and an organic material and conductive particles. The present invention relates to a method for manufacturing a gas adsorbent.
　従来、ガス吸着性の有機材料と、有機材料中に分散する導電性粒子とを含むガスセンサが、提供されている。例えば特許文献１には、並行するように円形状に配置された一対の導電線を含む電気絶縁性基材と、前記一対の導電線に接触する化学感受性ポリマーと、この化学感受性ポリマー中に分散する炭素粒子とを含むケミレジスタが、開示されている。このケミレジスタにおいては、化学感受性ポリマーがガス中の揮発性有機化合物などを吸着すると、電気抵抗値の変化が生じる。このケミレジスタを用いると、ケミレジスタの電気抵抗値の変化に基づいて、ガス中の揮発性有機化合物などを検出できる。 Conventionally, a gas sensor including a gas adsorbing organic material and conductive particles dispersed in the organic material has been provided. For example, in Patent Document 1, an electrically insulating substrate including a pair of conductive wires arranged in a circular shape so as to be parallel to each other, a chemically sensitive polymer in contact with the pair of conductive wires, and dispersed in the chemically sensitive polymer A chemi-resistor is disclosed that includes carbon particles that perform. In this chemi-resistor, when a chemically sensitive polymer adsorbs a volatile organic compound or the like in a gas, a change in electric resistance value occurs. When this chemi-resistor is used, volatile organic compounds in the gas can be detected based on a change in the electrical resistance value of the chemi-resistor.
米国特許第７１８９３６０号明細書US Pat. No. 7,189,360
　本開示の課題は、有機材料と導電性粒子とを含み、ガスに曝露された場合に生じる電気抵抗値の変化に乱れが生じにくく、かつガスに曝露された場合に電気抵抗値の変化が生じやすいガス吸着体、ガス吸着体を備えるガスセンサ、及びガス吸着体の製造方法を、提供することである。 It is an object of the present disclosure to include an organic material and conductive particles. The change in electrical resistance value that occurs when exposed to gas is less likely to be disturbed, and the change in electrical resistance value occurs when exposed to gas. An easy-to-use gas adsorber, a gas sensor including the gas adsorber, and a method for manufacturing the gas adsorber are provided.
　本開示の一態様に係るガス吸着体は、導電性粒子と、前記導電性粒子の少なくとも一部を覆う有機材料とを含む。前記ガス吸着体は、多孔質である。 The gas adsorbent according to one embodiment of the present disclosure includes conductive particles and an organic material that covers at least a part of the conductive particles. The gas adsorbent is porous.
　本開示の一態様に係るガスセンサは、前記ガス吸着体と、前記ガス吸着体に電気的に接続する電極とを備える。 A gas sensor according to an aspect of the present disclosure includes the gas adsorber and an electrode that is electrically connected to the gas adsorber.
　本開示の一態様に係るガス吸着体の製造方法は、有機材料と、導電性粒子と、溶剤とを含有する混合液を準備し、前記混合液から成形体を形成し、前記成形体中の前記溶剤を揮発させ、前記成形体中の前記有機材料の一部を熱分解させることを含む。 A method for producing a gas adsorbent according to an aspect of the present disclosure includes preparing a mixed liquid containing an organic material, conductive particles, and a solvent, forming a molded body from the mixed liquid, Volatilizing the solvent and thermally decomposing part of the organic material in the molded body.
図１Ａは本開示の一実施形態におけるガス吸着体の製造工程で作製される成形体を示す概略の断面図、図１Ｂは図１Ａに示す成形体から溶剤が揮発した後の状態を示す概略の断面図、図１Ｃは本発明の一実施形態におけるガス吸着体を示す概略の断面図である。FIG. 1A is a schematic cross-sectional view showing a molded body produced in the manufacturing process of a gas adsorbent according to an embodiment of the present disclosure, and FIG. 1B is a schematic view showing a state after the solvent is volatilized from the molded body shown in FIG. 1A. Sectional drawing and FIG. 1C are schematic sectional drawings which show the gas adsorber in one Embodiment of this invention. 図２Ａ、図２Ｂ、図２Ｃ及び図２Ｄは、それぞれ実施例のサンプル１、サンプル２、サンプル３及びサンプル４の、切断面の透過電子顕微鏡写真である。2A, 2B, 2C, and 2D are transmission electron micrographs of cut surfaces of Sample 1, Sample 2, Sample 3, and Sample 4, respectively. 図３Ａ、図３Ｂ、図３Ｃ及び図３Ｄは、それぞれ実施例のサンプル１、サンプル２、サンプル３及びサンプル４の、切断面の透過電子顕微鏡写真である。3A, FIG. 3B, FIG. 3C, and FIG. 3D are transmission electron micrographs of cut surfaces of Sample 1, Sample 2, Sample 3, and Sample 4, respectively. 図４は、実施例における、応答性及びノイズの評価で使用した試験用のガスセンサの構成の概略を示す平面図である。FIG. 4 is a plan view schematically showing the configuration of a test gas sensor used in the evaluation of responsiveness and noise in Examples. 図５は、実施例における、応答性及びノイズの評価の結果を示すグラフであり、横軸は経過時間を、縦軸はサンプル１及び２の規格化された電気抵抗値を示す。FIG. 5 is a graph showing the results of evaluation of responsiveness and noise in the example, in which the horizontal axis represents the elapsed time, and the vertical axis represents the normalized electric resistance values of Samples 1 and 2. 図６は、実施例における、応答性及びノイズの評価で使用した試験用のガスセンサの構成の概略を示す平面図である。FIG. 6 is a plan view schematically illustrating the configuration of a test gas sensor used in the evaluation of responsiveness and noise in Examples. 図７は、実施例における、感度の評価の結果を示すグラフであり、横軸は経過時間を、縦軸はサンプル２及び４の規格化された電気抵抗値を示す。FIG. 7 is a graph showing the results of sensitivity evaluation in Examples, in which the horizontal axis represents elapsed time and the vertical axis represents normalized electrical resistance values of Samples 2 and 4.
　まず、本開示の完成に至った経緯の概略を説明する。 First, an outline of the process that led to the completion of the present disclosure will be described.
　有機材料と、有機材料中に分散する導電性粒子とを含むガス吸着体を、ガスに曝露して、ガス中の化学物質を吸着させた場合は、ガス吸着体に電気抵抗値の変化が生じる。電気抵抗値の変化の一因は、有機材料が化学物質を吸着して膨張することでガス吸着体中の導電性粒子間の距離が変化することにあると、推察される。このガス吸着体の電気抵抗値の変化を利用して、ガス中の化学物質を検出できる。すなわち、ガス吸着体を備えるガスセンサを用いて、ガス中の化学物質を検出できる。 When a gas adsorber containing an organic material and conductive particles dispersed in the organic material is exposed to a gas and a chemical substance in the gas is adsorbed, a change in electric resistance value occurs in the gas adsorber. . One cause of the change in the electrical resistance value is presumed that the distance between the conductive particles in the gas adsorbent changes due to the organic material adsorbing the chemical substance and expanding. A chemical substance in the gas can be detected using the change in the electric resistance value of the gas adsorbent. That is, a chemical substance in the gas can be detected using a gas sensor including a gas adsorbent.
　しかし、このようなガス吸着体に化学物質を吸着させた場合には、電気抵抗値の変化に乱れが生じやすい。電気抵抗値の変化の乱れとは、例えば電気抵抗値が滑らかに変化せずに細かい上下動などが生じることをいう。電気抵抗値の変化の乱れは、ガスセンサを用いて得られる化学物質の検出結果にノイズを生じさせてしまう。また、ガス吸着体をガスに曝露させた場合の、ガス吸着体の電気抵抗値の変化の程度が大きいほど、及び電気抵抗値の変化が速やかに生じるほど、化学物質を速やかにかつ正確に検出できる。しかし、有機材料及び導電性粒子の選択などによるガス吸着体の性能向上には限界があった。 However, when a chemical substance is adsorbed on such a gas adsorbent, the change in electric resistance value is likely to be disturbed. Disturbance in the change of the electric resistance value means that, for example, the electric resistance value does not change smoothly and fine vertical movement occurs. Disturbances in the change in the electrical resistance value cause noise in the detection result of the chemical substance obtained using the gas sensor. In addition, when the gas adsorber is exposed to gas, the greater the degree of change in the electric resistance value of the gas adsorber and the quicker the change in the electric resistance value, the faster and more accurately the chemical substance is detected. it can. However, there has been a limit to improving the performance of the gas adsorber by selecting an organic material and conductive particles.
　そこで、発明者らは、化学物質を含むガスに曝露された場合の電気抵抗値の変化に乱れが生じにくく、かつガスに曝露された場合に電気抵抗値の変化が生じやすいガス吸着体を開発すべく、鋭意研究の結果、本開示の完成に至った。 Therefore, the inventors have developed a gas adsorbent that is less likely to be disturbed in the change in electrical resistance value when exposed to a gas containing a chemical substance and that is likely to change in electrical resistance value when exposed to a gas. Therefore, as a result of earnest research, the present disclosure has been completed.
　次に、本開示の一実施形態について、図１Ａ、図１Ｂ及び図１Ｃを参照して説明する。 Next, an embodiment of the present disclosure will be described with reference to FIGS. 1A, 1B, and 1C.
　本実施形態に係るガス吸着体１の製造方法は、次のステップを含む。 The manufacturing method of the gas adsorbent 1 according to the present embodiment includes the following steps.
　有機材料３と、導電性粒子２と、溶剤とを含有する混合液を準備する。 Prepare a mixed solution containing the organic material 3, the conductive particles 2, and the solvent.
　混合液から成形体４を形成する。 The formed body 4 is formed from the mixed solution.
　成形体４中の溶剤を揮発させる。 The solvent in the molded body 4 is volatilized.
　成形体４中の有機材料３の一部を熱分解させる。 ¡Part of the organic material 3 in the molded body 4 is thermally decomposed.
　本実施形態に係るガス吸着体１は、導電性粒子２と、導電性粒子２の少なくとも一部を覆う有機材料３とを含む。ガス吸着体１は、多孔質である。このガス吸着体１は、上記の製造方法で製造されうる。 The gas adsorbent 1 according to this embodiment includes conductive particles 2 and an organic material 3 that covers at least a part of the conductive particles 2. The gas adsorbent 1 is porous. The gas adsorbent 1 can be manufactured by the above manufacturing method.
　本実施形態に係るガス吸着体１は、ガスに曝露されることでガス中の化学物質を吸着すると、電気抵抗値が変化する。本実施形態では、ガス吸着体１がガスに曝露されることでガス中の化学物質を吸着した場合、ガス吸着体１に電気抵抗値の変化が生じやすい。さらに、本実施形態では、ガス吸着体１の電気抵抗値の変化に乱れが生じにくい。 When the gas adsorbent 1 according to the present embodiment adsorbs a chemical substance in the gas by being exposed to the gas, the electric resistance value changes. In the present embodiment, when the gas adsorbent 1 is exposed to gas and adsorbs a chemical substance in the gas, the gas adsorbent 1 is likely to change in electric resistance value. Furthermore, in this embodiment, the change in the electric resistance value of the gas adsorbent 1 is not easily disturbed.
　本実施形態に係るガスセンサ１０は、上記のガス吸着体１と、ガス吸着体１に接触する電極５とを備える。このガスセンサ１０を用いると、ガス中の化学物質を精度良く検出できる。 The gas sensor 10 according to the present embodiment includes the gas adsorbent 1 described above and an electrode 5 in contact with the gas adsorbent 1. If this gas sensor 10 is used, the chemical substance in gas can be detected accurately.
　ガス吸着体１の製造方法について、更に詳細に説明する。 The manufacturing method of the gas adsorbent 1 will be described in more detail.
　まず、有機材料３と、導電性粒子２と、溶剤とを含有する混合液を準備する。 First, a mixed solution containing an organic material 3, conductive particles 2, and a solvent is prepared.
　有機化合物について説明する。有機化合物は、ガス吸着性を有することが好ましい。ガス吸着性とは、ガスに曝露された場合にガス中に含まれる化学物質を吸着する性質のことをいう。化学物質の例は、揮発性有機化合物及び無機化合物を含む。揮発性有機化合物の例は、ケトン類、アミン類、アルコール類、芳香族炭化水素類、アルデヒド類、エステル類、有機酸、メチルメルカプタン、及びジスルフィドを含む。無機化合物の例は、硫化水素、二酸化硫黄、及び二硫化炭素を含む。有機材料３は、少なくとも一種の化学物質を吸着する性質を有することが好ましい。有機材料３がガス吸着性を有することは、技術常識に基づいて判断されうる。例えば、有機材料３をガスに曝露してから、有機材料３をガスクロマトグラフ質量分析計で分析すると、ガス由来の化学物質が検出される場合には、有機材料３はガス吸着性を有すると判断される。有機材料３は、少なくとも一種の揮発性有機化合物を吸着する性質を有することが好ましい。 Explanation of organic compounds. The organic compound preferably has gas adsorbability. Gas adsorbability refers to the property of adsorbing chemical substances contained in gas when exposed to gas. Examples of chemical substances include volatile organic compounds and inorganic compounds. Examples of volatile organic compounds include ketones, amines, alcohols, aromatic hydrocarbons, aldehydes, esters, organic acids, methyl mercaptans, and disulfides. Examples of inorganic compounds include hydrogen sulfide, sulfur dioxide, and carbon disulfide. The organic material 3 preferably has a property of adsorbing at least one kind of chemical substance. It can be judged based on technical common sense that the organic material 3 has gas adsorbability. For example, when the organic material 3 is exposed to gas and then analyzed by a gas chromatograph mass spectrometer, if a chemical substance derived from gas is detected, the organic material 3 is determined to have gas adsorbability. Is done. The organic material 3 preferably has a property of adsorbing at least one volatile organic compound.
　有機材料３は、ガス吸着体１が吸着すべき化学物質の種類、ガス吸着体１中の導電性粒子２の種類などに応じて、選択される。有機材料３は、例えば、高分子及び低分子からなる群より選ばれる少なくとも一種の材料を含む。有機材料３は、特に高分子を含むことが好ましい。有機材料３が高分子を含むと、ガス吸着体１は耐熱性を有することができる。 The organic material 3 is selected according to the type of chemical substance to be adsorbed by the gas adsorbent 1 and the type of conductive particles 2 in the gas adsorbent 1. The organic material 3 includes, for example, at least one material selected from the group consisting of a polymer and a low molecule. The organic material 3 particularly preferably contains a polymer. When the organic material 3 contains a polymer, the gas adsorbent 1 can have heat resistance.
　有機材料３の好ましい例は、ガスクロマトグラフにおけるカラムの固定相として市販されている材料を含む。より具体的には、有機材料３は、例えば、ポリアルキレングリコール類、ポリエステル類、シリコーン類、グリセロール類、ニトリル類、ジカルボン酸モノエステル類及び脂肪族アミン類からなる群より選ばれる少なくとも一種の材料を含む。この場合、有機材料３は、ガス中の化学物質、特に揮発性有機化合物を、容易に吸着できる。 A preferable example of the organic material 3 includes a material that is commercially available as a stationary phase of a column in a gas chromatograph. More specifically, the organic material 3 is, for example, at least one material selected from the group consisting of polyalkylene glycols, polyesters, silicones, glycerols, nitriles, dicarboxylic acid monoesters, and aliphatic amines. including. In this case, the organic material 3 can easily adsorb chemical substances in the gas, particularly volatile organic compounds.
　ポリアルキレングリコール類は、例えば、ポリエチレングリコール（耐熱温度１７０℃）を含む。ポリエステル類は、例えば、ポリ（ジエチレングリコールアジペート）及びポリ（エチレンサクシネート）からなる群より選ばれる少なくとも一種の材料を含む。シリコーン類は、例えば、ジメチルシリコーン、フェニルメチルシリコーン、トリフルオロプロピルメチルシリコーン及びシアノシリコーン（耐熱温度２７５℃）からなる群より選ばれる少なくとも一種の材料を含む。グリセロール類は、例えば、ジグリセロール（耐熱温度１５０℃）を含む。ニトリル類は、例えば、Ｎ，Ｎ－ビス（２－シアノエチル）ホルムアミド（耐熱温度１２５℃）及び１，２，３－トリス（２－シアノエトキシ）プロパン（耐熱温度１５０℃）からなる群より選ばれる少なくとも一種の材料を含む。ジカルボン酸モノエステル類は、例えば、ニトロテレフタル酸修飾ポリエチレングリコール（耐熱温度２７５℃）及びジエチレングリコールサクシネート（耐熱温度２２５℃）からなる群より選ばれる少なくとも一種の材料を含む。脂肪族アミン類は、例えば、テトラヒドロキシエチルエチレンジアミン（耐熱温度１２５℃）を含む。 Polyalkylene glycols include, for example, polyethylene glycol (heat resistant temperature: 170 ° C.). Polyesters include, for example, at least one material selected from the group consisting of poly (diethylene glycol adipate) and poly (ethylene succinate). The silicones include, for example, at least one material selected from the group consisting of dimethylsilicone, phenylmethylsilicone, trifluoropropylmethylsilicone, and cyanosilicone (heat-resistant temperature 275 ° C.). Glycerols include, for example, diglycerol (heat resistant temperature 150 ° C.). Nitriles are selected from the group consisting of, for example, N, N-bis (2-cyanoethyl) formamide (heat resistant temperature 125 ° C.) and 1,2,3-tris (2-cyanoethoxy) propane (heat resistant temperature 150 ° C.). Contains at least one material. The dicarboxylic acid monoesters include, for example, at least one material selected from the group consisting of nitroterephthalic acid-modified polyethylene glycol (heat resistant temperature 275 ° C.) and diethylene glycol succinate (heat resistant temperature 225 ° C.). Aliphatic amines include, for example, tetrahydroxyethylethylenediamine (heat resistant temperature 125 ° C.).
　導電性粒子２は、例えば、炭素材料、導電性ポリマー、金属、金属酸化物、半導体、超伝導体及び錯化合物からなる群より選ばれる少なくとも一種の材料を含む。炭素材料は、例えばカーボンブラック、グラファイト、コークス、カーボンナノチューブ、グラフェン及びフラーレンからなる群より選ばれる少なくとも一種の材料を含む。導電性ポリマーは、例えばポリアニリン、ポリチオフェン、ポリピロール及びポリアセチレンからなる群より選ばれる少なくとも一種の材料を含む。金属は、例えば、銀、金、銅、白金及びアルミニウムからなる群より選ばれる少なくとも一種の材料を含む。金属酸化物は、例えば酸化インジウム、酸化スズ、酸化タングステン、酸化亜鉛及び酸化チタンからなる群より選ばれる少なくとも一種の材料を含む。半導体は、例えば、ケイ素、ガリウムヒ素、リン化インジウム及び硫化モリブデンからなる群より選ばれる少なくとも一種の材料を含む。超伝導体は、例えば、ＹＢａ2Ｃｕ3Ｏ7及びＴｌ2Ｂａ2Ｃａ2Ｃｕ3Ｏ10からなる群より選ばれる少なくとも一種の材料を含む。錯化合物は、例えば、テトラメチルパラフェニレンジアミンとクロラニルとの錯化合物、テトラシアノキノジメタンとアルカリ金属との錯化合物、テトラチアフルバレンとハロゲンとの錯化合物、イリジウムとハロカルボニル化合物との錯化合物、及びテトラシアノ白金からなる群より選ばれる少なくとも一種の材料を含む。 The conductive particles 2 include, for example, at least one material selected from the group consisting of carbon materials, conductive polymers, metals, metal oxides, semiconductors, superconductors, and complex compounds. The carbon material includes, for example, at least one material selected from the group consisting of carbon black, graphite, coke, carbon nanotube, graphene, and fullerene. The conductive polymer includes, for example, at least one material selected from the group consisting of polyaniline, polythiophene, polypyrrole, and polyacetylene. The metal includes, for example, at least one material selected from the group consisting of silver, gold, copper, platinum, and aluminum. The metal oxide includes, for example, at least one material selected from the group consisting of indium oxide, tin oxide, tungsten oxide, zinc oxide, and titanium oxide. The semiconductor includes, for example, at least one material selected from the group consisting of silicon, gallium arsenide, indium phosphide, and molybdenum sulfide. The superconductor includes, for example, at least one material selected from the group consisting of YBa 2 Cu 3 O 7 and Tl 2 Ba 2 Ca 2 Cu 3 O 10 . Complex compounds include, for example, complex compounds of tetramethylparaphenylenediamine and chloranil, complex compounds of tetracyanoquinodimethane and alkali metals, complex compounds of tetrathiafulvalene and halogen, complex compounds of iridium and halocarbonyl compounds. And at least one material selected from the group consisting of tetracyanoplatinum.
　導電性粒子２は、炭素材料を含むことが好ましい。導電性粒子２がカーボンブラックを含むことが特に好ましい。導電性粒子２が炭素材料、特にカーボンブラックを含むと、ガスに曝露された場合にガス吸着体１の電気抵抗値の変化が特に生じやすい。 The conductive particles 2 preferably contain a carbon material. It is particularly preferable that the conductive particles 2 contain carbon black. When the conductive particles 2 contain a carbon material, particularly carbon black, the electric resistance value of the gas adsorbent 1 is particularly likely to change when exposed to gas.
　導電性粒子２の平均粒径は、例えば１０ｎｍ以上３００ｎｍ以下である。この場合、ガス吸着体１の製造時にガス吸着体１を多孔質化させやすい。導電性粒子２の平均粒径は、導電性粒子２の電子顕微鏡写真から求めた粒径の個数基準の算術平均値である。具体的には、電子顕微鏡写真を画像処理して電子顕微鏡写真に現れる導電性粒子２の各々の面積を導出し、この導電性粒子２の面積から、導電性粒子２の各々の真円換算の直径を算出し、この直径の平均値を求めることにより、平均粒径が得られる。 The average particle diameter of the conductive particles 2 is, for example, 10 nm or more and 300 nm or less. In this case, it is easy to make the gas adsorbent 1 porous when the gas adsorbent 1 is manufactured. The average particle diameter of the conductive particles 2 is an arithmetic average value based on the number of particle diameters obtained from an electron micrograph of the conductive particles 2. Specifically, the area of each of the conductive particles 2 appearing in the electron micrograph is derived by performing image processing on the electron micrograph, and from the area of the conductive particle 2, each of the conductive particles 2 is converted into a perfect circle. The average particle diameter is obtained by calculating the diameter and obtaining the average value of the diameters.
　溶剤は、有機材料３を溶解させ又は分散させることができ、かつ成形体４から揮発しうるのであれば、制限はない。溶剤は、例えばジメチルスルホキシド、ジメチルホルムアミド、トルエン、クロロホルム、アセトン、アセトニトリル、メタノール、エタノール、イソプロパノール、テトラヒドロフラン、酢酸エチル、及び酢酸ブチルからなる群から選択される少なくとも一種の成分を含有する。 The solvent is not limited as long as the organic material 3 can be dissolved or dispersed and can be volatilized from the molded body 4. The solvent contains at least one component selected from the group consisting of dimethyl sulfoxide, dimethylformamide, toluene, chloroform, acetone, acetonitrile, methanol, ethanol, isopropanol, tetrahydrofuran, ethyl acetate, and butyl acetate, for example.
　次に、図１Ａに示すように、混合液から成形体４を形成する。成形体４は、膜状であることが好ましい。この場合、膜状のガス吸着体１を製造できる。なお、膜には、フィルム、シート、及び層などが、含まれうる。成形体４の形成方法に制限はない。例えば混合液をインクジェット法、ディスペンス法といった方法で塗布することで、成形体４を形成できる。成形体４の厚みは例えば０．１μｍ以上１０μｍ以下である。成形体４は、溶剤と有機材料３とを含む液７中に導電性粒子２が分散した構造を有する。 Next, as shown in FIG. 1A, a molded body 4 is formed from the mixed solution. The molded body 4 is preferably in the form of a film. In this case, the film-like gas adsorbent 1 can be manufactured. In addition, a film, a sheet | seat, a layer, etc. may be contained in a film | membrane. There is no restriction | limiting in the formation method of the molded object 4. FIG. For example, the molded body 4 can be formed by applying the mixed liquid by a method such as an inkjet method or a dispensing method. The thickness of the molded body 4 is, for example, 0.1 μm or more and 10 μm or less. The molded body 4 has a structure in which conductive particles 2 are dispersed in a liquid 7 containing a solvent and an organic material 3.
　次に、成形体４中の溶剤を揮発させる。溶剤を揮発させる方法に制限はない。例えば成形体４に熱処理（以下、第一熱処理ともいう）を施すことで、成形体４から溶剤を揮発させることができる。成形体４を減圧下に配置することで、成形体４から溶剤を揮発させることもできる。成形体４に減圧下で第一熱処理を施すことで、成形体４から溶剤を揮発させることもできる。第一熱処理の温度は、溶剤の種類に応じ、溶剤の揮発を促進できるように適宜設定される。第一熱処理の温度は、例えば３０℃以上９０℃以下である。また、第一熱処理の温度は、有機材料３が熱分解せず、又は熱分解が進行しにくいように、設計されることが好ましい。そのために、例えば第一熱処理の温度は、有機材料３の耐熱温度より３０℃低い温度未満であることが好ましい。第一熱処理の時間は、第一熱処理によって成形体４中の溶剤の全て又は殆どが揮発するように、設計されることが好ましい。第一熱処理の時間は、例えば１０分以上６０分以下である。 Next, the solvent in the molded body 4 is volatilized. There is no limitation on the method for volatilizing the solvent. For example, the solvent can be volatilized from the molded body 4 by subjecting the molded body 4 to a heat treatment (hereinafter also referred to as a first heat treatment). By disposing the molded body 4 under reduced pressure, the solvent can be volatilized from the molded body 4. The solvent can be volatilized from the molded body 4 by subjecting the molded body 4 to a first heat treatment under reduced pressure. The temperature of the first heat treatment is appropriately set so as to promote the volatilization of the solvent according to the type of the solvent. The temperature of 1st heat processing is 30 degreeC or more and 90 degrees C or less, for example. Moreover, it is preferable that the temperature of the first heat treatment is designed so that the organic material 3 is not thermally decomposed or hardly thermally decomposes. Therefore, for example, the temperature of the first heat treatment is preferably less than 30 ° C. lower than the heat resistant temperature of the organic material 3. The time for the first heat treatment is preferably designed so that all or most of the solvent in the molded body 4 is volatilized by the first heat treatment. The time for the first heat treatment is, for example, not less than 10 minutes and not more than 60 minutes.
　成形体４中から溶剤が揮発すると、図１Ｂに示すように、成形体４中の導電性粒子２が移動して、近接し合う粒子間の間隔が小さくなり、導電性粒子２が連なった構造が形成されやすい。これは、溶剤が揮発することで成形体４の流動、形状変化、体積変化などが生じ、それらによって導電性粒子２の移動が促されることが一因であると推察される。成形体４に第一熱処理を施すことで溶剤を揮発させると、成形体４中の導電性粒子２の移動が促進されて、導電性粒子２が連なった構造が特に形成されやすくなる。 When the solvent is volatilized from the molded body 4, as shown in FIG. 1B, the conductive particles 2 in the molded body 4 move, the interval between adjacent particles becomes smaller, and the conductive particles 2 are connected. Is easily formed. It is surmised that this is because the volatilization of the solvent causes the flow, shape change, volume change, etc. of the molded body 4 to promote the movement of the conductive particles 2. When the solvent is volatilized by subjecting the molded body 4 to the first heat treatment, the movement of the conductive particles 2 in the molded body 4 is promoted, and a structure in which the conductive particles 2 are continuous is particularly easily formed.
　次に、成形体４中の有機材料３の一部を熱分解させる。すなわち、有機材料３のうち熱分解しなかった残部を成形体４に残留させる。有機材料３の一部を熱分解させるためには、成形体４に熱処理（以下、第二熱処理ともいう）を施すことが好ましい。第二熱処理の温度は、有機材料３の熱分解を促進できるように適宜設計される。第二熱処理の温度は、例えば有機材料３の耐熱温度より３０℃低い温度以上、耐熱温度より３０℃高い温度以下である。第二熱処理の時間は、第二熱処理によって成形体４中の有機材料３の一部の熱分解が完了するように、すなわち、有機材料３の残部は熱分解せずに残存するように、設計されることが好ましい。第二熱処理の時間は、例えば１０分以上１２０分以下である。 Next, a part of the organic material 3 in the molded body 4 is thermally decomposed. That is, the remaining part of the organic material 3 that has not been thermally decomposed is left in the molded body 4. In order to thermally decompose a part of the organic material 3, it is preferable to heat-treat the molded body 4 (hereinafter also referred to as a second heat treatment). The temperature of the second heat treatment is appropriately designed so that the thermal decomposition of the organic material 3 can be promoted. The temperature of the second heat treatment is, for example, not less than a temperature 30 ° C. lower than the heat resistant temperature of the organic material 3 and not higher than 30 ° C. higher than the heat resistant temperature. The time of the second heat treatment is designed so that the thermal decomposition of a part of the organic material 3 in the molded body 4 is completed by the second heat treatment, that is, the remainder of the organic material 3 remains without being thermally decomposed. It is preferred that The time for the second heat treatment is, for example, not less than 10 minutes and not more than 120 minutes.
　有機材料３の一部が熱分解すると、熱分解した有機材料３は成形体４から除去されて、空隙１１が生じる。また、有機材料３のうち、熱分解せずに成形体４に残留した残部は、導電性粒子２にまとわりつくように配置されやすい。このように有機材料３の一部が熱分解することにより、図１Ｃに示すように、ガス吸着体１が得られる。ガス吸着体１は、導電性粒子２と、導電性粒子２の少なくとも一部を覆う有機材料３とを含む。このガス吸着体１は、有機材料３の一部が除去されることで形成された空隙１１を有することで、多孔質である。 When a part of the organic material 3 is thermally decomposed, the thermally decomposed organic material 3 is removed from the molded body 4, and a void 11 is generated. In addition, the remaining part of the organic material 3 that remains in the molded body 4 without being thermally decomposed is easily disposed so as to cling to the conductive particles 2. As shown in FIG. 1C, the gas adsorbent 1 is obtained by thermally decomposing a part of the organic material 3 in this manner. The gas adsorbent 1 includes conductive particles 2 and an organic material 3 that covers at least a part of the conductive particles 2. The gas adsorbent 1 is porous by having a void 11 formed by removing a part of the organic material 3.
　なお、成形体４中の溶剤を揮発させるステップと、成形体４中の有機材料３の一部を熱分解させるステップとは、時系列的に完全に分離していてもよく、完全には分離していなくてもよい。すなわち、成形体４中の溶剤を揮発させるステップにおいて、有機材料３の一部の熱分解が不完全に進行していてもよい。また、成形体４中の有機材料３の一部を熱分解させるステップにおいて、成形体４中に溶剤が残留し、かつこの溶剤の揮発が進行してもよい。ただし、成形体４中の溶剤を揮発させるステップにおいては、有機材料３の一部の熱分解は進行しないことが好ましい。 Note that the step of volatilizing the solvent in the molded body 4 and the step of thermally decomposing a part of the organic material 3 in the molded body 4 may be completely separated in time series or completely separated. You don't have to. That is, in the step of volatilizing the solvent in the molded body 4, the thermal decomposition of a part of the organic material 3 may proceed incompletely. Further, in the step of thermally decomposing a part of the organic material 3 in the molded body 4, a solvent may remain in the molded body 4 and the volatilization of the solvent may proceed. However, in the step of volatilizing the solvent in the molded body 4, it is preferable that the thermal decomposition of a part of the organic material 3 does not proceed.
　成形体４中の溶剤を揮発させるに当たって、特に成形体４に第一熱処理を施すことで、成形体４中の溶剤を揮発させることが好ましい。さらに、成形体４中の有機材料３の一部を熱分解させるに当たって、成形体４に第一熱処理の場合よりも高温の第二の熱処理を施すことで、成形体４中の有機材料３の一部を熱分解させることが好ましい。この場合、第一の熱処理の温度と第二の熱処理の温度とを調整することで、第一の熱処理では溶剤を揮発させる際に有機材料３の熱分解が進行させず又は熱分解を進行しにくくし、第二の熱処理では有機材料３の一部を効率良く熱分解させることが、容易である。 In volatilizing the solvent in the molded body 4, it is preferable to volatilize the solvent in the molded body 4 by applying a first heat treatment to the molded body 4. Furthermore, in thermally decomposing a part of the organic material 3 in the molded body 4, the molded body 4 is subjected to a second heat treatment at a higher temperature than in the case of the first heat treatment. It is preferable to thermally decompose a part. In this case, by adjusting the temperature of the first heat treatment and the temperature of the second heat treatment, when the solvent is volatilized in the first heat treatment, thermal decomposition of the organic material 3 does not proceed or thermal decomposition proceeds. In the second heat treatment, it is easy to efficiently thermally decompose a part of the organic material 3.
　上記のとおり、ガス吸着体１は、導電性粒子２と、導電性粒子２の少なくとも一部を覆う有機材料３とを含む。ガス吸着体１は、多孔質である。 As described above, the gas adsorbent 1 includes the conductive particles 2 and the organic material 3 that covers at least a part of the conductive particles 2. The gas adsorbent 1 is porous.
　上記の説明では、ガス吸着体１は、有機材料３の一部が熱分解して除去されることで形成された空隙１１を有することで、多孔質化されている。しかし、ガス吸着体１は、これとは異なる機序で形成された空隙１１を有することによって多孔質化されていてもよい。例えば、成形体４にビーズを含有させてから、このビーズを成形体４から除去することで、ビーズがあった箇所に空隙１１を形成してもよい。この場合、例えば上記の成形体４を形成するための混合液にビーズを含有させ、この混合液から成形体を形成することで、成形体４にビーズを含有させることができる。ビーズは、例えば加熱されることで分解若しくは揮発しやすい材料、紫外線などの光を受けることで分解若しくは揮発しやすい材料、又はオゾンなどの反応性が高いガスと反応することで分解若しくは揮発しやすい材料などから、作製される。その場合、ビーズを加熱し、ビーズに光を照射し、又はビーズを反応性が高いガスと反応させることで、成形体４からビーズを除去し、空隙１１を形成できる。これら以外にも、ビーズの特性に応じた適宜の方法で成形体４からビーズを除去してよい。ビーズは、例えばビーズに要求される特性に応じた適宜の有機材料から作製されうる。ビーズの粒子径は、空隙１１に望まれるサイズに応じて選択されるが、例えば１０ｎｍ以上１μｍ以下である。ガス吸着体１は、互いに異なる機序で形成された複数種の空隙１１を有することによって多孔質化されていてもよい。 In the above description, the gas adsorbent 1 is made porous by having the voids 11 formed by thermally decomposing and removing a part of the organic material 3. However, the gas adsorbent 1 may be made porous by having voids 11 formed by a mechanism different from this. For example, the voids 11 may be formed at locations where the beads were present by allowing the molded body 4 to contain beads and then removing the beads from the molded body 4. In this case, for example, beads can be contained in the molded body 4 by forming the molded body from the mixed liquid by including beads in the mixed liquid for forming the molded body 4 described above. For example, beads are easily decomposed or volatilized by heating, are easily decomposed or volatilized by receiving light such as ultraviolet rays, or are easily decomposed or volatilized by reacting with a highly reactive gas such as ozone. Made from materials. In that case, the beads can be removed from the molded body 4 by forming the voids 11 by heating the beads, irradiating the beads with light, or reacting the beads with a highly reactive gas. In addition to these, the beads may be removed from the molded body 4 by an appropriate method according to the characteristics of the beads. The beads can be made from an appropriate organic material according to the properties required for the beads, for example. The particle diameter of the beads is selected according to the size desired for the void 11 and is, for example, not less than 10 nm and not more than 1 μm. The gas adsorbent 1 may be made porous by having a plurality of types of voids 11 formed by different mechanisms.
　混合液中の有機材料３、導電性粒子２及び溶剤の量は、適宜設定される。例えば混合液中の溶剤の量及び導電性粒子２の量を調整することで、成形体４から溶剤を揮発させた場合の、導電性粒子２の連なりの発生などを、制御できる。また、例えば混合液中の有機材料３の量を調整することで、ガス吸着体１中の空隙１１の程度、すなわち空隙率、などを制御できる。混合液中の有機材料３の量は、例えば溶剤１ｍｌに対して１ｍｇ以上３０ｍｇ以下である。混合物中の導電性粒子２の量は、例えば溶剤１ｍｌに対して１ｍｇ以上３０ｍｇ以下である。 The amount of the organic material 3, the conductive particles 2, and the solvent in the mixed solution is appropriately set. For example, by adjusting the amount of the solvent and the amount of the conductive particles 2 in the mixed solution, it is possible to control the occurrence of a series of the conductive particles 2 when the solvent is volatilized from the molded body 4. Further, for example, by adjusting the amount of the organic material 3 in the mixed solution, the degree of the void 11 in the gas adsorbent 1, that is, the porosity can be controlled. The amount of the organic material 3 in the mixed solution is, for example, 1 mg or more and 30 mg or less with respect to 1 ml of the solvent. The amount of the conductive particles 2 in the mixture is, for example, 1 mg or more and 30 mg or less with respect to 1 ml of the solvent.
　ガス吸着体１は、膜状であることが好ましい。すなわち、ガス吸着体１は、多孔質な膜であることが好ましい。この場合、ガス吸着体１の比表面積が大きくなることで、ガス吸着体１がガス中の化学物質を吸着しやすくなる。ガス吸着体１の厚みは、例えば０．１μｍ以上１０μｍ以下である。 The gas adsorbent 1 is preferably in the form of a film. That is, the gas adsorbent 1 is preferably a porous film. In this case, since the specific surface area of the gas adsorbent 1 is increased, the gas adsorbent 1 can easily adsorb the chemical substance in the gas. The thickness of the gas adsorbent 1 is, for example, not less than 0.1 μm and not more than 10 μm.
　本実施形態に係るガス吸着体１がガスに曝露されると、有機材料３がガス中の化学物質を吸着し、それに伴ってガス吸着体１の電気抵抗値が変化する。 When the gas adsorbent 1 according to the present embodiment is exposed to gas, the organic material 3 adsorbs a chemical substance in the gas, and the electric resistance value of the gas adsorbent 1 changes accordingly.
　本実施形態では、ガス吸着体１がガスに曝露された際の電気抵抗値の変化が速やかに生じやすい。また、電気抵抗値の変化の程度が大きくなりやすい。その一因は、ガス吸着体１が多孔質であることで、ガス吸着体１がガス中の化学物質を効率良く吸着できることにあると、推察される。また、他の一因は、ガス吸着体１中に導電性粒子２が連なった構造が形成され、この構造が電流の径路となっていることにあると、推察される。すなわち、導電性粒子２が連なった構造中の隣り合う導電性粒子２の間にある有機材料３がガスを吸着して膨張すると、電流の径路を構成する導電性粒子２の間隔が変化しやすく、そのために電気抵抗値の変化が生じやすいと推察される。 In the present embodiment, a change in the electrical resistance value when the gas adsorbent 1 is exposed to gas is likely to occur quickly. In addition, the degree of change in the electrical resistance value tends to increase. One reason is presumed that the gas adsorbent 1 can adsorb chemical substances in the gas efficiently because the gas adsorbent 1 is porous. In addition, it is presumed that another reason is that a structure in which the conductive particles 2 are continuous in the gas adsorbent 1 is formed, and this structure serves as a current path. That is, when the organic material 3 between the adjacent conductive particles 2 in the structure in which the conductive particles 2 are continuous adsorbs gas and expands, the interval between the conductive particles 2 constituting the current path is likely to change. Therefore, it is assumed that the electrical resistance value is likely to change.
　さらに、本実施形態では、ガス吸着体１の電気抵抗値が変化する場合の、電気抵抗値の変化に乱れが生じにくい。すなわち、電気抵抗値は滑らかに変化しやすい。その理由は、次のとおりであると推察される。有機材料と有機材料中に分散している導電性粒子とを含むガス吸着体の電気抵抗値の変化に乱れが生じるのは、有機材料中で導電性粒子がブラウン運動などにより移動して、導電性粒子間の位置関係が変化しやすいからであると推察される。一方、本実施形態に係るガス吸着体１は、図１Ｃに示すように、有機材料３と導電性粒子２とを含むものの、有機材料３は導電性粒子２の少なくとも一部を覆っており、全体としては多孔質であるので、導電性粒子２が有機材料３中で移動しにくい。そのため、ガス吸着体１中で導電性粒子２同士の位置関係は変化しにくい。そのため、ガス吸着体１の電気抵抗値が変化する場合に、電気抵抗値の変化に乱れが生じにくいと考えられる。 Furthermore, in this embodiment, when the electric resistance value of the gas adsorbent 1 changes, the change in the electric resistance value is hardly disturbed. That is, the electrical resistance value is likely to change smoothly. The reason is assumed to be as follows. The change in the electrical resistance value of the gas adsorbent containing the organic material and the conductive particles dispersed in the organic material is disturbed because the conductive particles move in the organic material due to Brownian motion, etc. This is presumably because the positional relationship between the sex particles is likely to change. On the other hand, although the gas adsorbent 1 according to the present embodiment includes the organic material 3 and the conductive particles 2 as shown in FIG. 1C, the organic material 3 covers at least a part of the conductive particles 2. Since the whole is porous, the conductive particles 2 are difficult to move in the organic material 3. Therefore, the positional relationship between the conductive particles 2 is hardly changed in the gas adsorbent 1. Therefore, when the electric resistance value of the gas adsorbent 1 changes, it is considered that the change in the electric resistance value is less likely to be disturbed.
　ガス吸着体１の空隙率は、１０％以上であることが好ましい。空隙率は、ガス吸着体１を切断した場合の切断面における空隙１１の面積割合と、定義される。切断面における空隙１１の面積は、切断面を電子顕微鏡で観察することで確認できる。ガス吸着体１の空隙率が１０％以上であると、ガス吸着体１がガスに曝露されて化学物質を吸着した場合に、電気抵抗値が特に変化しやすくなる。これは、ガスが空隙１１に侵入しやすいために、ガス中の化学物質がガス吸着体１に効率良く吸着されるからであると、推察される。空隙率は１５％以上であればより好ましい。また、空隙率は３０％以下であることが好ましく、２５％以下であればより好ましい。 The porosity of the gas adsorbent 1 is preferably 10% or more. The porosity is defined as the area ratio of the void 11 in the cut surface when the gas adsorbent 1 is cut. The area of the gap 11 in the cut surface can be confirmed by observing the cut surface with an electron microscope. When the porosity of the gas adsorbent 1 is 10% or more, when the gas adsorbent 1 is exposed to gas and adsorbs a chemical substance, the electrical resistance value is particularly likely to change. This is presumed to be because the chemical substance in the gas is efficiently adsorbed to the gas adsorbent 1 because the gas easily enters the gap 11. The porosity is more preferably 15% or more. Further, the porosity is preferably 30% or less, and more preferably 25% or less.
　ガス吸着体１を備えるガスセンサ１０について説明する。ガスセンサ１０は、ガス吸着体１と、ガス吸着体１に電気的に接続する電極５とを備える。このガスセンサ１０を用いると、ガス吸着体１が化学物質を含むガスに曝露された場合に、ガス吸着体１が化学物質を吸着することで、ガス吸着体１の電気抵抗値が変化する。この電気抵抗値の変化に基づいて、化学物質を検出できる。本実施形態では、上記のとおり、ガス吸着体１に生じる電気抵抗値の変化に乱れが生じにくく、かつガスに曝露された場合に電気抵抗値の変化が生じやすい。このため、ガスセンサ１０を用いることで、ガス中の化学物質を精度良く検出できる。 The gas sensor 10 provided with the gas adsorbent 1 will be described. The gas sensor 10 includes a gas adsorber 1 and an electrode 5 that is electrically connected to the gas adsorber 1. When this gas sensor 10 is used, when the gas adsorbent 1 is exposed to a gas containing a chemical substance, the gas adsorbent 1 adsorbs the chemical substance, whereby the electric resistance value of the gas adsorbent 1 changes. A chemical substance can be detected based on the change in the electrical resistance value. In the present embodiment, as described above, the change in the electric resistance value generated in the gas adsorbent 1 is not easily disturbed, and the electric resistance value is likely to change when exposed to gas. For this reason, the chemical substance in gas can be detected accurately by using the gas sensor 10.
　ガスセンサ１０の一具体例を、図１Ｃを参照して説明する。ガスセンサ１０は、ガス吸着体１及び電極５を備える。電極５は、第一電極５１及び第二電極５２を含む。ガスセンサ１０は、更に基材６を備える。 A specific example of the gas sensor 10 will be described with reference to FIG. 1C. The gas sensor 10 includes a gas adsorbent 1 and an electrode 5. The electrode 5 includes a first electrode 51 and a second electrode 52. The gas sensor 10 further includes a substrate 6.
　基材６は電気絶縁性を有する。基材６は一つの面（以下、支持面６１という）を有し、支持面６１上に、第一電極５１、第二電極５２及びガス吸着体１が配置されている。基材６は、例えば、支持面６１と直交する方向の厚みを有する板の形状を有する。第一電極５１及び第二電極５２は、支持面６１の向く方向と直交する方向に間隔をあけて配置されている。 The base material 6 has electrical insulation. The substrate 6 has one surface (hereinafter referred to as a support surface 61), and the first electrode 51, the second electrode 52, and the gas adsorbent 1 are disposed on the support surface 61. The substrate 6 has, for example, a plate shape having a thickness in a direction orthogonal to the support surface 61. The first electrode 51 and the second electrode 52 are arranged at an interval in a direction orthogonal to the direction in which the support surface 61 faces.
　ガス吸着体１は、基材６の支持面６１上に配置され、かつ第一電極５１及び第二電極５２を覆っている。これにより、ガス吸着体１と第一電極５１及び第二電極５２の各々とが接触している。なお、ガス吸着体１と第一電極５１及び第二電極５２の各々との電気的接続は、いかなる構造によって達成されてもよい。例えばガス吸着体１は、第一電極５１の全体に接触していてもよく、一部に接触していてもよい。またガス吸着体１は、第二電極５２の全体に接触していてもよく、一部に接触していてもよい。 The gas adsorbent 1 is disposed on the support surface 61 of the substrate 6 and covers the first electrode 51 and the second electrode 52. Thereby, the gas adsorbent 1 and each of the first electrode 51 and the second electrode 52 are in contact with each other. The electrical connection between the gas adsorber 1 and each of the first electrode 51 and the second electrode 52 may be achieved by any structure. For example, the gas adsorbent 1 may be in contact with the entire first electrode 51 or may be in contact with a part thereof. Further, the gas adsorbent 1 may be in contact with the entire second electrode 52 or may be in contact with a part thereof.
　このガスセンサ１０の第一電極５１と第二電極５２との間に電圧が印加されると、ガス吸着体１に、電圧及びガス吸着体１の電気抵抗値に応じた電流が流れる。このため、ガス吸着体１の電気抵抗値を測定できる。この電気抵抗値の値から化学物質を検出できる。なお、第一電極５１と第二電極５２との間に定電圧を印加した状態での第一電極５１と第二電極５２との間に流れる電流の値から化学物質を検出してもよい。ガス吸着体１に定電流を流した状態での第一電極５１と第二電極５２との間の電圧降下量から化学物質を検出してもよい。すなわち、ガス吸着体１の電気抵抗値の変化に応じて変化する指標に基づいて化学物質を検出すればよい。 When a voltage is applied between the first electrode 51 and the second electrode 52 of the gas sensor 10, a current corresponding to the voltage and the electric resistance value of the gas adsorbent 1 flows through the gas adsorbent 1. For this reason, the electrical resistance value of the gas adsorbent 1 can be measured. A chemical substance can be detected from the electric resistance value. In addition, you may detect a chemical substance from the value of the electric current which flows between the 1st electrode 51 and the 2nd electrode 52 in the state which applied the constant voltage between the 1st electrode 51 and the 2nd electrode 52. FIG. You may detect a chemical substance from the voltage drop amount between the 1st electrode 51 and the 2nd electrode 52 in the state which sent the constant current to the gas adsorption body 1. FIG. That is, the chemical substance may be detected based on an index that changes in accordance with a change in the electric resistance value of the gas adsorbent 1.
　このガスセンサ１０を製造する場合は、例えば基材６の支持面６１上に第一電極５１及び第二電極５２を設けてから、支持面６１上に、上記のとおり混合液から成形体４を形成する。成形体４は、第一電極５１及び第二電極５２を覆うように形成する。続いて、この成形体４から、上記のとおりガス吸着体１を作製する。 When manufacturing the gas sensor 10, for example, the first electrode 51 and the second electrode 52 are provided on the support surface 61 of the base 6, and then the molded body 4 is formed on the support surface 61 from the mixed liquid as described above. To do. The molded body 4 is formed so as to cover the first electrode 51 and the second electrode 52. Subsequently, the gas adsorbent 1 is produced from the molded body 4 as described above.
　以下、本実施形態に関する試験方法及び試験結果を提示する。なお、下記の試験方法及び試験結果は、本実施形態の構成を制限するものではない。 Hereinafter, the test method and test results related to this embodiment will be presented. Note that the following test methods and test results do not limit the configuration of the present embodiment.
　１．原料の準備
　導電性粒子２として平均粒径４４ｎｍのカーボンブラックを準備した。溶剤として、ジメチルホルムアミドを準備した。有機材料３として、ポリエチレングリコールを準備した。 1. Preparation of Raw Material Carbon black having an average particle size of 44 nm was prepared as the conductive particles 2. Dimethylformamide was prepared as a solvent. Polyethylene glycol was prepared as the organic material 3.
　２．ガス吸着体のサンプルの作製
　２－１．サンプル１
　溶媒に導電性粒子２及び有機材料３を加えて撹拌することで、導電性粒子２を１０ｍｇ／ｍｌの濃度で含み、かつ有機材料３を１０ｍｇ／ｍｌの濃度で含む混合液を調製した。 2. 2. Preparation of gas adsorbent sample 2-1. Sample 1
By adding the conductive particles 2 and the organic material 3 to the solvent and stirring, a liquid mixture containing the conductive particles 2 at a concentration of 10 mg / ml and the organic material 3 at a concentration of 10 mg / ml was prepared.
　混合液をインクジェット法で塗布することで、膜状の成形体４を形成した。この成形体４に５０℃で２０分間熱処理を施すことで、成形体４から溶媒を揮発させた。これにより、サンプル１を得た。 The film-like molded body 4 was formed by applying the mixed solution by an inkjet method. The molded body 4 was heat treated at 50 ° C. for 20 minutes to volatilize the solvent from the molded body 4. Thereby, Sample 1 was obtained.
　２－２．サンプル２
　溶媒に導電性粒子２及び有機材料３を加えて撹拌することで、導電性粒子２を１０ｍｇ／ｍｌの濃度で含み、かつ有機材料３を１０ｍｇ／ｍｌの濃度で含む混合液を調製した。 2-2. Sample 2
By adding the conductive particles 2 and the organic material 3 to the solvent and stirring, a liquid mixture containing the conductive particles 2 at a concentration of 10 mg / ml and the organic material 3 at a concentration of 10 mg / ml was prepared.
　混合液をインクジェット法で塗布することで、膜状の成形体４を形成した。この成形体４に５０℃で２０分間熱処理（第一熱処理）を施すことで、成形体４から溶媒を揮発させた。続いて成形体４に１７０℃で６０分間熱処理（第二熱処理）を施すことで、成形体４中の有機材料３の一部を熱分解させた。これにより、サンプル２を得た。 The film-like molded body 4 was formed by applying the mixed solution by an inkjet method. The solvent was volatilized from the molded body 4 by subjecting the molded body 4 to a heat treatment (first heat treatment) at 50 ° C. for 20 minutes. Subsequently, a part of the organic material 3 in the molded body 4 was thermally decomposed by subjecting the molded body 4 to a heat treatment (second heat treatment) at 170 ° C. for 60 minutes. Thereby, Sample 2 was obtained.
　２－３．サンプル３
　溶媒に導電性粒子２及び有機材料３を加えて撹拌することで、導電性粒子２を２．５ｍｇ／ｍｌの濃度で含み、かつ有機材料３を１７．５ｍｇ／ｍｌの濃度で含む混合液を調製した。 2-3. Sample 3
By adding the conductive particles 2 and the organic material 3 to the solvent and stirring, a mixed liquid containing the conductive particles 2 at a concentration of 2.5 mg / ml and the organic material 3 at a concentration of 17.5 mg / ml Prepared.
　混合液をインクジェット法で塗布することで、膜状である成形体４を形成した。この成形体４に５０℃で２０分間熱処理を施すことで、成形体４から溶媒を揮発させた。これにより、サンプル３を得た。 The mixture was applied by an ink jet method to form a film-like molded body 4. The molded body 4 was heat treated at 50 ° C. for 20 minutes to volatilize the solvent from the molded body 4. As a result, Sample 3 was obtained.
　２－４．サンプル４
　溶媒に導電性粒子２及び有機材料３を加えて撹拌することで、導電性粒子２を２．５ｍｇ／ｍｌの濃度で含み、かつ有機材料３を１７．５ｍｇ／ｍｌの濃度で含む混合液を調製した。 2-4. Sample 4
By adding the conductive particles 2 and the organic material 3 to the solvent and stirring, a mixed liquid containing the conductive particles 2 at a concentration of 2.5 mg / ml and the organic material 3 at a concentration of 17.5 mg / ml Prepared.
　混合液をインクジェット法で塗布することで、膜状の成形体４を形成した。この成形体４に５０℃で２０分間熱処理（第一熱処理）を施すことで、成形体４から溶媒を揮発させた。続いて成形体４に１７０℃で６０分間熱処理（第二熱処理）を施すことで、成形体４中の有機材料３の一部を熱分解させた。これにより、サンプル４を得た。 The film-like molded body 4 was formed by applying the mixed solution by an inkjet method. The solvent was volatilized from the molded body 4 by subjecting the molded body 4 to a heat treatment (first heat treatment) at 50 ° C. for 20 minutes. Subsequently, a part of the organic material 3 in the molded body 4 was thermally decomposed by subjecting the molded body 4 to a heat treatment (second heat treatment) at 170 ° C. for 60 minutes. As a result, Sample 4 was obtained.
　３．切断面観察
　３－１．画像観察
　画像観察用に、各サンプルを、１００ｎｍの厚みを有するように作製した。各サンプルを、厚み方向に切断し、切断面を透過電子顕微鏡で観察した。サンプル１、サンプル２、サンプル３及びサンプル４の切断面の透過電子顕微鏡画像を、それぞれ図２Ａ、図２Ｂ、図２Ｃ及び図２Ｄ示す。また、サンプル１、サンプル２、サンプル３及びサンプル４の切断面の、更に拡大した透過電子顕微鏡画像を、それぞれ図３Ａ、図３Ｂ、図３Ｃ及び図３Ｄに示す。 3. 3. Observation of cut surface 3-1. Image observation Each sample was prepared to have a thickness of 100 nm for image observation. Each sample was cut in the thickness direction, and the cut surface was observed with a transmission electron microscope. The transmission electron microscope images of the cut surfaces of Sample 1, Sample 2, Sample 3 and Sample 4 are shown in FIGS. 2A, 2B, 2C and 2D, respectively. Further, further enlarged transmission electron microscope images of cut surfaces of Sample 1, Sample 2, Sample 3, and Sample 4 are shown in FIGS. 3A, 3B, 3C, and 3D, respectively.
　サンプル１及びサンプル３については、図２Ａ及び図２Ｃからは導電性粒子２を示す濃色の部分と、白色の部分とが認められた。図３Ａ及び図３Ｃを参照すれば、白色の部分の殆どは有機材料３であることが確認でき、そのためサンプル１及びサンプル３は多孔質とは認められない。 Regarding Sample 1 and Sample 3, from FIG. 2A and FIG. 2C, a dark colored portion showing conductive particles 2 and a white portion were recognized. Referring to FIG. 3A and FIG. 3C, it can be confirmed that most of the white portion is the organic material 3, so that the samples 1 and 3 are not recognized as porous.
　サンプル２及びサンプル４については、図２Ｂ及び図２Ｄからは導電性粒子２を示す濃色の部分と、白色の部分とが認められた。図３Ｂ及び図３Ｄを参照すれば、白色の部分は空隙１１であり、そのためサンプル２及びサンプル４は多孔質であると認められる。また、図３Ｂ及び図３Ｄによれば、導電性粒子２が有機材料３に覆われていることが確認できる。 As for Sample 2 and Sample 4, from FIG. 2B and FIG. 2D, a dark colored portion showing conductive particles 2 and a white portion were recognized. Referring to FIG. 3B and FIG. 3D, the white part is the void 11, and thus it is recognized that Sample 2 and Sample 4 are porous. Further, according to FIGS. 3B and 3D, it can be confirmed that the conductive particles 2 are covered with the organic material 3.
　３－２．空隙率調査
　サンプル１、サンプル２、サンプル３及びサンプル４の各々の切断面の透過電子顕微鏡画像を撮影し、コントラストに基づいて空隙１１を特定した。さらに、切断面の面積に対する空隙１１の面積割合を算出した。これにより空隙率を測定した。各サンプルにつき、空隙率の測定を３回行い、その結果の平均値を各サンプルの空隙率として特定した。 3-2. Void ratio investigation The transmission electron microscope image of each cut surface of sample 1, sample 2, sample 3 and sample 4 was photographed, and the void 11 was specified based on the contrast. Furthermore, the area ratio of the space | gap 11 with respect to the area of a cut surface was computed. This measured the porosity. About each sample, the porosity was measured 3 times and the average value of the result was specified as the porosity of each sample.
　その結果、サンプル１の空隙率は７．５６％、サンプル２の空隙率は１４．８８％、サンプル３の空隙率は３．５９％、サンプル４の空隙率は２６．２９％であった。この結果からも、サンプル１及びサンプル３は空隙１１が僅かしかなく、多孔質とは認められないのに対して、サンプル２及びサンプル４は多孔質であると認められる。 As a result, the porosity of sample 1 was 7.56%, the porosity of sample 2 was 14.88%, the porosity of sample 3 was 3.59%, and the porosity of sample 4 was 26.29%. Also from this result, sample 1 and sample 3 have few voids 11 and are not recognized to be porous, whereas sample 2 and sample 4 are recognized to be porous.
　４．センサ特性の評価
　４－１．応答性及びノイズの評価
　サンプル１とサンプル２の各々を用いて、試験用のガスセンサ１０を作製した。なお、上記のとおり、サンプル１とサンプル２とは、原料である混合液中の導電性粒子２と有機材料３との比率は同じであるが、サンプル２は製造過程で第二熱処理によって多孔質化されているのに対し、サンプル１の製造過程には第二熱処理が含まれず、サンプル１は多孔質化していない。 4). 4. Evaluation of sensor characteristics 4-1. Evaluation of Responsiveness and Noise Using each of Sample 1 and Sample 2, a test gas sensor 10 was produced. As described above, sample 1 and sample 2 have the same ratio of conductive particles 2 and organic material 3 in the mixed liquid as a raw material, but sample 2 is porous by the second heat treatment in the manufacturing process. In contrast, the manufacturing process of Sample 1 does not include the second heat treatment, and Sample 1 is not made porous.
　試験用のガスセンサ１０の構造の概略は図４に示すとおりである。このガスセンサ１０には、電気絶縁性の基材６の上に、リング状の配置された第一電極５１と、リング状に配置された第二電極５２とを、同心円状に設けた。さらに、基材６の上に第一電極５１及び第二電極５２を覆うように電気絶縁性の膜（絶縁膜９）を設けた。絶縁膜９には、直径５μｍの八個の第一開口７１を、直径Ｄ１が６００μｍである仮想円の円周上に、第一電極５１に通じるように設けた。また、直径５μｍの八個の第二開口７２を、直径Ｄ２が８００μｍである仮想円の円周上に、第二電極５２に通じるように設けた。さらに、基材６の上に、絶縁膜９を覆うように、ガス吸着体１である各サンプルを、１μｍの厚みを有するように設けた。そのためガス吸着体１は、第一開口７１及び第二開口７２を通じて第一電極５１及び第二電極５２のそれぞれに接触する。ガス吸着体１の図４に示す径Ｄ３の寸法は９００μｍである。また、ガスセンサ１０には、第一電極５１の一端から延びてガス吸着体１の外側の突出する第一端子８１と、第二電極５２の一端から延びてガス吸着体１の外側に突出する第二端子８２とを、設けた。 The outline of the structure of the test gas sensor 10 is as shown in FIG. In the gas sensor 10, a first electrode 51 arranged in a ring shape and a second electrode 52 arranged in a ring shape are provided concentrically on the electrically insulating base 6. Furthermore, an electrically insulating film (insulating film 9) was provided on the substrate 6 so as to cover the first electrode 51 and the second electrode 52. In the insulating film 9, eight first openings 71 having a diameter of 5 μm were provided on the circumference of a virtual circle having a diameter D1 of 600 μm so as to communicate with the first electrode 51. Eight second openings 72 having a diameter of 5 μm were provided on the circumference of a virtual circle having a diameter D2 of 800 μm so as to communicate with the second electrode 52. Furthermore, each sample as the gas adsorbent 1 was provided on the base material 6 so as to cover the insulating film 9 so as to have a thickness of 1 μm. Therefore, the gas adsorbent 1 comes into contact with each of the first electrode 51 and the second electrode 52 through the first opening 71 and the second opening 72. The diameter D3 of the gas adsorbent 1 shown in FIG. 4 is 900 μm. The gas sensor 10 includes a first terminal 81 that extends from one end of the first electrode 51 and protrudes outside the gas adsorbent 1, and a first terminal that extends from one end of the second electrode 52 and protrudes outside the gas adsorbent 1. Two terminals 82 were provided.
　第一端子８１と第二端子８２との間に定電圧を印加した状態で、ガスセンサ１０を窒素気流中に配置してから、気流中にノナナールを約１５秒間混入した。この過程での、第一端子８１と第二端子８２との間に流れる電流を測定し、その結果からガス吸着体１である各サンプルの電気抵抗値を算出した。 In a state where a constant voltage was applied between the first terminal 81 and the second terminal 82, the gas sensor 10 was placed in a nitrogen stream, and then nonanal was mixed into the stream for about 15 seconds. In this process, the current flowing between the first terminal 81 and the second terminal 82 was measured, and the electric resistance value of each sample as the gas adsorbent 1 was calculated from the result.
　図５に、各サンプルの電気抵抗値の経時変化を示す。横軸は経過時間を示し、横軸の目盛りで約３０秒の時点から約４５秒の時点までの間、気流中にノナナールを混入した。また、縦軸は、各サンプルの規格化された電気抵抗値を示す。なお、規格化された電気抵抗値は、事前に各サンプルの電気抵抗値を窒素気流中で測定した結果を１として規定した。 FIG. 5 shows the change over time in the electrical resistance value of each sample. The horizontal axis represents the elapsed time, and nonanal was mixed in the airflow from the time point of about 30 seconds to the time point of about 45 seconds on the scale of the horizontal axis. The vertical axis represents the normalized electrical resistance value of each sample. The standardized electrical resistance value was defined as 1 as a result of measuring the electrical resistance value of each sample in a nitrogen stream in advance.
　図５に示す結果によると、サンプル２の電気抵抗値は、気流中にノナナールが混入された時点で速やかに上昇し、気流中からノナナールがなくなったら速やかに低下した。また、電気抵抗値の変化は滑らかであり、顕著な乱れは認められなかった。一方、サンプル１の電気抵抗値は、気流中にノナナールが混入された時点から緩やかに上昇し、気流中からノナナールがなくなったら緩やかに低下した。また、電気抵抗値の変化には細かな上下動が認められた。このため、サンプル２を備えるガスセンサ１０は、サンプル１を備えるガスセンサ１０に比べて、応答性が良好であり、かつノイズが少ないといえる。 According to the results shown in FIG. 5, the electrical resistance value of sample 2 quickly increased when nonanal was mixed in the air stream, and rapidly decreased when nonanal disappeared from the air stream. Moreover, the change in electrical resistance value was smooth, and no significant disturbance was observed. On the other hand, the electrical resistance value of sample 1 gradually increased from the time when nonanal was mixed in the air stream, and gradually decreased when nonanal disappeared from the air stream. In addition, a slight vertical movement was observed in the change in the electrical resistance value. For this reason, it can be said that the gas sensor 10 including the sample 2 has better responsiveness and less noise than the gas sensor 10 including the sample 1.
　４－２．感度の評価
　サンプル２とサンプル４の各々を用いて、試験用のガスセンサ１０を作製した。なお、上記のとおり、サンプル２とサンプル４とは、いずれも製造過程で第二熱処理によって多孔質化されている。ただし、サンプル２よりもサンプル４の方が原料である混合液中の導電性粒子２に対する有機材料３の比率が高く、サンプル２よりもサンプル４の方が空隙率が高い。 4-2. Evaluation of Sensitivity Using each of Sample 2 and Sample 4, a test gas sensor 10 was produced. As described above, both the sample 2 and the sample 4 are made porous by the second heat treatment in the manufacturing process. However, the ratio of the organic material 3 to the conductive particles 2 in the mixed liquid in which the sample 4 is a raw material is higher than that of the sample 2, and the porosity of the sample 4 is higher than that of the sample 2.
　試験用のガスセンサ１０の構造の概略は図６に示すとおりである。このガスセンサ１０には、電気絶縁性の基材６の上に、第一電極５１と第二電極５２とを、くし形電極系を構成するように設けた。くし形電極系の、くし形の歯に沿った方向の寸法Ｌ１は５２０μｍ、くし形の歯に直交する方向の寸法Ｌ２は５００μｍである。さらに、基材６の上に第一電極５１及び第二電極５２を覆うように電気絶縁性の膜（絶縁膜９）を設けた。絶縁膜９には、図６中に示す幅５μｍの帯状の開口７０を、第一電極５１及び第二電極５２に重なるように設けた。図６中に示す開口７０の中心間の寸法Ｌ３は６０μｍである。さらに、基材６の上に、絶縁膜９を覆うように、ガス吸着体１である各サンプルを、１μｍの厚みを有するように設けた。そのためガス吸着体１は、開口７０を通じて第一電極５１及び第二電極５２に接触する。ガス吸着体１の図６に示す径Ｄ３の寸法は９００μｍである。また、ガスセンサ１０には、第一電極５１の一端から延びてガス吸着体１の外側の突出する第一端子８１と、第二電極５２の一端から延びてガス吸着体１の外側に突出する第二端子８２とを、設けた。 The outline of the structure of the test gas sensor 10 is as shown in FIG. In the gas sensor 10, the first electrode 51 and the second electrode 52 are provided on the electrically insulating base 6 so as to constitute a comb-shaped electrode system. The dimension L1 of the comb electrode system in the direction along the comb-shaped teeth is 520 μm, and the dimension L2 in the direction perpendicular to the comb-shaped teeth is 500 μm. Furthermore, an electrically insulating film (insulating film 9) was provided on the substrate 6 so as to cover the first electrode 51 and the second electrode 52. In the insulating film 9, a strip-shaped opening 70 having a width of 5 μm shown in FIG. 6 is provided so as to overlap the first electrode 51 and the second electrode 52. The dimension L3 between the centers of the openings 70 shown in FIG. 6 is 60 μm. Furthermore, each sample as the gas adsorbent 1 was provided on the base material 6 so as to cover the insulating film 9 so as to have a thickness of 1 μm. Therefore, the gas adsorbent 1 comes into contact with the first electrode 51 and the second electrode 52 through the opening 70. The diameter D3 of the gas adsorbent 1 shown in FIG. 6 is 900 μm. The gas sensor 10 includes a first terminal 81 that extends from one end of the first electrode 51 and protrudes outside the gas adsorbent 1, and a first terminal that extends from one end of the second electrode 52 and protrudes outside the gas adsorbent 1. Two terminals 82 were provided.
　第一端子８１と第二端子８２との間に定電圧を印加した状態で、ガスセンサ１０を窒素気流中に配置してから、気流中にノナナールを約１５秒間混入した。この過程での、第一端子８１と第二端子８２との間に流れる電流を測定し、その結果からガス吸着体１である各サンプルの電気抵抗値を算出した。 In a state where a constant voltage was applied between the first terminal 81 and the second terminal 82, the gas sensor 10 was placed in a nitrogen stream, and then nonanal was mixed into the stream for about 15 seconds. In this process, the current flowing between the first terminal 81 and the second terminal 82 was measured, and the electric resistance value of each sample as the gas adsorbent 1 was calculated from the result.
　図７に、各サンプルの電気抵抗値の経時変化を示す。横軸は経過時間を示し、横軸の目盛りで約３０秒の時点から約４５秒の時点までの間、気流中にノナナールを混入した。また、縦軸は、各サンプルの規格化された電気抵抗値を示す。なお、規格化された電気抵抗値は、事前に各サンプルの電気抵抗値を窒素気流中で測定した結果を１として規定した。 FIG. 7 shows the change over time in the electrical resistance value of each sample. The horizontal axis represents the elapsed time, and nonanal was mixed in the airflow from the time point of about 30 seconds to the time point of about 45 seconds on the scale of the horizontal axis. The vertical axis represents the normalized electrical resistance value of each sample. The standardized electrical resistance value was defined as 1 as a result of measuring the electrical resistance value of each sample in a nitrogen stream in advance.
　図７に示す結果によると、サンプル２とサンプル４のいずれの電気抵抗値も、気流中にノナナールが混入された時点で上昇し、気流中からノナナールがなくなったら低下した。また、サンプル４の電気抵抗値の変化の程度は、サンプル２の電気抵抗値の変化の程度よりも大きかった。このため、サンプル２よりも多孔質なサンプル４を備えるガスセンサ１０は、サンプル２を備えるガスセンサ１０よりも、感度が高いといえる。 According to the results shown in FIG. 7, the electrical resistance values of Sample 2 and Sample 4 both increased when nonanal was mixed in the air stream and decreased when nonanal disappeared from the air stream. Further, the degree of change in the electric resistance value of Sample 4 was larger than the degree of change in the electric resistance value of Sample 2. For this reason, it can be said that the gas sensor 10 including the sample 4 that is more porous than the sample 2 has higher sensitivity than the gas sensor 10 including the sample 2.
　以上の実施形態及び実施例から明らかなように、本開示の第１の態様に係るガス吸着体（１）は、導電性粒子（２）と、導電性粒子（２）の少なくとも一部を覆う有機材料（３）とを含むガス吸着体（１）である。ガス吸着体（１）は多孔質である。 As is clear from the above embodiments and examples, the gas adsorbent (1) according to the first aspect of the present disclosure covers the conductive particles (2) and at least a part of the conductive particles (2). A gas adsorbent (1) containing an organic material (3). The gas adsorbent (1) is porous.
　第１の態様によれば、有機材料（３）と導電性粒子（２）とを含み、ガスに曝露された場合に電気抵抗値の変化が生じやすく、かつ電気抵抗値が変化した場合に電気抵抗値に乱れが生じにくいガス吸着体（１）が得られる。 According to the first aspect, the organic material (3) and the conductive particles (2) are included, the electrical resistance value is likely to change when exposed to gas, and the electrical resistance value changes when the electrical resistance value changes. A gas adsorbent (1) is obtained in which the resistance value is less likely to be disturbed.
　本開示の第２の態様に係るガス吸着体（１）では、第１の態様において、ガス吸着体（１）は膜状である。 In the gas adsorbent (1) according to the second aspect of the present disclosure, in the first aspect, the gas adsorbent (1) is a film.
　第２の態様によれば、ガス吸着体（１）の比表面積を大きくして、ガス吸着体（１）がガス中の化学物質を吸着しやすくできる。 According to the second aspect, the specific surface area of the gas adsorbent (1) can be increased, and the gas adsorbent (1) can easily adsorb the chemical substance in the gas.
　本開示の第３の態様に係るガス吸着体（１）では、第１又は第２の態様において、導電性粒子（２）は、炭素材料を含む。 In the gas adsorbent (1) according to the third aspect of the present disclosure, in the first or second aspect, the conductive particles (2) include a carbon material.
　第３の態様によれば、ガスに曝露された場合にガス吸着体（１）の電気抵抗値の変化が特に生じやすい。 According to the third aspect, the electrical resistance value of the gas adsorbent (1) is particularly likely to change when exposed to gas.
　本開示の第４の態様に係るガス吸着体（１）では、第１から第３のいずれか一の態様において、有機材料（３）は、高分子を含む。 In the gas adsorbent (1) according to the fourth aspect of the present disclosure, in any one of the first to third aspects, the organic material (3) includes a polymer.
　第４の態様によれば、ガス吸着体（１）は耐熱性を有することができる。 According to the fourth aspect, the gas adsorbent (1) can have heat resistance.
　本開示の第５の態様に係るガス吸着体（１）では、第１から第４のいずれか一の態様において、ガス吸着体（１）の空隙率が１０％以上である。 In the gas adsorbent (1) according to the fifth aspect of the present disclosure, in any one of the first to fourth aspects, the porosity of the gas adsorbent (1) is 10% or more.
　第５の態様によると、ガス吸着体（１）がガスに曝露されて化学物質を吸着した場合に、ガス吸着体（１）の電気抵抗値が特に変化しやすくなる。 According to the fifth aspect, when the gas adsorber (1) is exposed to gas and adsorbs a chemical substance, the electric resistance value of the gas adsorber (1) is particularly likely to change.
　本開示の第６の態様に係るガスセンサ（１０）は、第１から第５のいずれか一の態様に係るガス吸着体（１）と、ガス吸着体（１）に電気的に接続する電極（５）とを備える。 A gas sensor (10) according to a sixth aspect of the present disclosure includes a gas adsorbent (1) according to any one of the first to fifth aspects, and an electrode electrically connected to the gas adsorbent (1) ( 5).
　第６の態様によれば、ガス吸着性の有機材料（３）と導電性粒子（２）とを含み、ガスに曝露された場合に電気抵抗値の変化が生じやすく、かつ電気抵抗値が変化した場合に電気抵抗値に乱れが生じにくいガス吸着体（１）を備えるガスセンサ（１０）が得られる。 According to the sixth aspect, it includes the gas adsorbing organic material (3) and the conductive particles (2), and the electrical resistance value is likely to change when exposed to the gas, and the electrical resistance value changes. In this case, the gas sensor (10) including the gas adsorbent (1) that is less likely to cause a disturbance in the electric resistance value is obtained.
　本開示の第７の態様に係るガス吸着体（１）の製造方法は、有機材料（３）と、導電性粒子（２）と、溶剤とを含有する混合液を準備し、混合液から成形体（４）を形成し、成形体（４）中の溶剤を揮発させ、成形体（４）中の有機材料（３）の一部を熱分解させることを含む。 The manufacturing method of the gas adsorbent (1) according to the seventh aspect of the present disclosure includes preparing a mixed solution containing the organic material (3), the conductive particles (2), and a solvent, and molding from the mixed solution. Forming a body (4), volatilizing a solvent in the molded body (4), and thermally decomposing a part of the organic material (3) in the molded body (4).
　第７の態様によれば、有機材料（３）と導電性粒子（２）とを含み、ガスに曝露された場合に電気抵抗値の変化が生じやすく、かつ電気抵抗値が変化した場合に電気抵抗値に乱れが生じにくいガス吸着体（１）を製造できる。 According to the seventh aspect, when the organic material (3) and the conductive particles (2) are included, the electrical resistance value is likely to change when exposed to the gas, and the electrical resistance value changes when the electrical resistance value changes. A gas adsorbent (1) in which the resistance value is hardly disturbed can be manufactured.
　本開示の第８の態様に係るガス吸着体（１）の製造方法では、第７の態様において、成形体（４）を膜状に形成することで、ガス吸着体（１）を膜状に形成する。 In the manufacturing method of the gas adsorbent (1) according to the eighth aspect of the present disclosure, in the seventh aspect, the gas adsorbent (1) is formed into a film by forming the molded body (4) into a film. Form.
　第８の態様によれば、ガス吸着体（１）の比表面積を大きくして、ガス吸着体（１）がガス中の化学物質を吸着しやすくできる。 According to the eighth aspect, the specific surface area of the gas adsorber (1) can be increased, and the gas adsorber (1) can easily adsorb the chemical substance in the gas.
　本開示の第９の態様に係るガス吸着体（１）の製造方法では、第７又は第８の態様において、成形体（４）に第一熱処理を施すことで、成形体（４）中の溶剤を揮発させ、成形体（４）に第一熱処理の場合よりも高温の第二熱処理を施すことで、成形体（４）中の有機材料（３）の一部を熱分解させる。 In the manufacturing method of the gas adsorbent (1) according to the ninth aspect of the present disclosure, in the seventh or eighth aspect, the first heat treatment is performed on the molded body (4), whereby the molded body (4) A part of the organic material (3) in the molded body (4) is thermally decomposed by volatilizing the solvent and subjecting the molded body (4) to a second heat treatment at a temperature higher than that of the first heat treatment.
　第９の態様によれば、成形体（４）中の有機材料（３）の一部を特に熱分解させやすく、そのため空隙１１を特に形成しやすい。 According to the ninth aspect, a part of the organic material (3) in the molded body (4) is particularly easily decomposed, so that the void 11 is particularly easily formed.
　本開示の第１０の態様に係るガス吸着体（１）の製造方法では、第７から第９のいずれか一の態様において、導電性粒子（２）は、炭素材料を含む。 In the method for manufacturing the gas adsorbent (1) according to the tenth aspect of the present disclosure, in any one of the seventh to ninth aspects, the conductive particles (2) include a carbon material.
　第１０の態様によれば、ガスに曝露された場合にガス吸着体（１）の電気抵抗値の変化が特に生じやすい。 According to the tenth aspect, a change in the electric resistance value of the gas adsorbent (1) is particularly likely to occur when exposed to gas.
　本開示の第１１の態様に係るガス吸着体（１）の製造方法では、第７から第１０のいずれか一の態様において、有機材料（３）は、高分子を含む。 In the method for producing a gas adsorbent (1) according to the eleventh aspect of the present disclosure, in any one of the seventh to tenth aspects, the organic material (3) includes a polymer.
　第１１の態様によれば、ガス吸着体（１）は耐熱性を有することができる。 According to the eleventh aspect, the gas adsorbent (1) can have heat resistance.
　１　　ガス吸着体
　２　　導電性粒子
　３　　有機材料
　４　　成形体
　５　　電極
　１０　ガスセンサ DESCRIPTION OF SYMBOLS 1 Gas adsorption body 2 Conductive particle 3 Organic material 4 Molded object 5 Electrode 10 Gas sensor

Claims (11)

  1. 導電性粒子と、
    前記導電性粒子の少なくとも一部を覆う有機材料とを含むガス吸着体であり、
    前記ガス吸着体は多孔質である、
    ガス吸着体。     Conductive particles;
    A gas adsorbent comprising an organic material covering at least a part of the conductive particles,
    The gas adsorbent is porous;
    Gas adsorber.
  2. 前記ガス吸着体は膜状である、
    請求項１に記載のガス吸着体。     The gas adsorber is in the form of a film,
    The gas adsorbent according to claim 1.
  3. 前記導電性粒子は、炭素材料を含む、
    請求項１又は２に記載のガス吸着体。     The conductive particles include a carbon material,
    The gas adsorbent according to claim 1 or 2.
  4. 前記有機材料は、高分子を含む、
    請求項１から３のいずれか一項に記載のガス吸着体。     The organic material includes a polymer,
    The gas adsorbent according to any one of claims 1 to 3.
  5. 前記ガス吸着体の空隙率が１０％以上である、
    請求項１から４のいずれか一項に記載のガス吸着体。     The porosity of the gas adsorber is 10% or more,
    The gas adsorbent according to any one of claims 1 to 4.
  6. 請求項１から５のいずれか一項に記載のガス吸着体と、
    前記ガス吸着体に電気的に接続する電極とを備える、
    ガスセンサ。     A gas adsorbent according to any one of claims 1 to 5;
    An electrode electrically connected to the gas adsorber,
    Gas sensor.
  7. 有機材料と、導電性粒子と、溶剤とを含有する混合液を準備し、
    前記混合液から成形体を形成し、
    前記成形体中の前記溶剤を揮発させ、
    前記成形体中の前記有機材料の一部を熱分解させることを含む、
    ガス吸着体の製造方法。     Prepare a liquid mixture containing an organic material, conductive particles, and a solvent,
    Forming a molded body from the mixed solution;
    Volatilizing the solvent in the molded body,
    Pyrolyzing a part of the organic material in the molded body,
    A method for producing a gas adsorbent.
  8. 前記成形体を膜状に形成することで、前記ガス吸着体を膜状に形成する、
    請求項７に記載のガス吸着体の製造方法。     By forming the molded body into a film, the gas adsorbent is formed into a film.
    The method for producing a gas adsorbent according to claim 7.
  9. 前記成形体に第一熱処理を施すことで、前記成形体中の前記溶剤を揮発させ、
    前記成形体に前記第一熱処理の場合よりも高温の第二熱処理を施すことで、前記成形体中の前記有機材料の前記一部を熱分解させる、
    請求項７又は８に記載のガス吸着体の製造方法。     By subjecting the molded body to a first heat treatment, the solvent in the molded body is volatilized,
    By subjecting the molded body to a second heat treatment at a higher temperature than in the case of the first heat treatment, the part of the organic material in the molded body is thermally decomposed.
    The method for producing a gas adsorbent according to claim 7 or 8.
  10. 前記導電性粒子は、炭素材料を含む、
    請求項７から９のいずれか一項に記載のガス吸着体の製造方法。     The conductive particles include a carbon material,
    The method for producing a gas adsorbent according to any one of claims 7 to 9.
  11. 前記有機材料は、高分子を含む、
    請求項７から１０のいずれか一項に記載のガス吸着体の製造方法。     The organic material includes a polymer,
    The method for producing a gas adsorbent according to any one of claims 7 to 10.
PCT/JP2019/012979 2018-03-30 2019-03-26 Gas adsorbent, gas sensor, and method for manufacturing gas adsorbent WO2019189245A1 (en)

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