JP2000146944A - Gas detection device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and accurately detect a specific gas by essentially isolating a colored layer to be colored by the specific gas from the fresh air excluding a fresh air introduction part and a fresh air unloading part. SOLUTION: A gas detection device essentially isolate the fresh air from a discolored layer excluding a fresh air introduction part and a fresh air unloading part. For example, a disk type gas detection device laminates the discolored layer 2 that is impregnated with an ink for detecting gas in a base (paper), a porous base 3, and a gas impermeable material 4 and connect them with a support 5. The porous base 3 is provided with an open pore at the side surface part of an outer end and a connection hole inside for permeating a specific gas, and each open pore becomes the introduction part and the unloading part of the fresh air. When the device is installed in an atmosphere containing the specific gas, the fresh air enters through the open pore of the side surface part of the outer end of the porous base 3, touches the specific gas from the outside of the disk-shaped colored layer 2, and starts discoloration from a circumferential part to a central part. The penetration fresh air is transmitted through the open pore and is unloaded from other open pores, thus detecting gas accurately without being affected by the fresh air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a gas detection device and a gas detection method.

[0002]

2. Description of the Related Art In recent years, awareness of environmental issues, hygiene issues, etc. has increased, and for example, ozone (oxidant), CO, CO
_{2. In} addition to NO _x and SO _x , there is an increasing demand for detection of various gases such as sulfur compounds, nitrogen compounds, carbon compounds, and chlorine compounds.

[0003] For example, ozone is used for sterilization / disinfection or disinfection or deodorization of foods, utensils and the like, or sterilization / disinfection or deodorization in a certain atmosphere, such as an operating room of a hospital, because of its excellent sterilization property. I have. On the other hand, ozone is extremely toxic and has an adverse effect on the human body, so its allowable concentration is limited. On the other hand, in the photochemical smog forecast,
The oxidant concentration in the atmosphere is an important factor.

[0004] Therefore, in order to monitor the ozone concentration, various detection methods have been developed. As a conventional ozone detection method, color change due to the reaction of the following formula (1) is mainly used.

[0005] As a detection method utilizing this principle, for example, a method of introducing a gas containing ozone into a potassium iodide solution and optically measuring the degree of discoloration in proportion to the amount of iodine generated by a colorimeter, or a simple type A method using a detection tube has been conventionally known.

[0006]

However, in the above-described optical detection method, the method is complicated, and it takes some time until a detection result is obtained. Also, the equipment for performing this method is very expensive. In particular, when trying to measure the ozone concentration at a plurality of locations at the same time, a large cost is required because a plurality of devices are required.

The method using the detection tube is simpler than the optical detection method, but is still expensive, and requires manual or automatic suction of the oxidant every time measurement is performed.

On the other hand, for example, there is known a gas indicator or the like in which an indicator layer which changes color by reacting with a specific gas and a diffusion layer which diffuses the specific gas are provided in a bag-shaped transparent member (Japanese Patent Laid-Open No. 7-1995). 49342, JP-A-7-72137
No., JP-A-8-122318, etc.). According to these indicators, it is possible to detect ozone and the like by a relatively simple method.

However, these gas indicators have only one vent, so that the atmospheric gas is difficult to circulate, and it is difficult to detect the gas quickly. Further, the gas indicator is susceptible to the influence of the gas flow of the atmosphere gas, and the degree of contact between the atmosphere gas and the indicator layer is not constant, so that ozone cannot be detected more accurately. In particular, it is necessary to develop a new technology in order to quantitatively detect ozone.

Thus, as is apparent from the example of ozone, a method for accurately detecting a specific gas by a relatively easy method has not yet been established.

Accordingly, an object of the present invention is to provide an apparatus and a method capable of easily and accurately detecting a specific gas.

[0012]

Means for Solving the Problems The present inventor has made intensive studies to solve the problems of the prior art, and as a result, has found that the above object can be achieved by employing an apparatus having a specific configuration. The present invention has been completed.

That is, the present invention relates to a gas detection device and a gas detection method described below.

1. It has a discoloration layer that changes color by a specific gas, an outside air introduction part for introducing outside air to the discoloration layer, and an outside air discharge part for discharging the introduced outside air, and the outside air and the discoloration layer except for the outside air introduction part and the outside air discharge part. And a gas detector substantially isolated from the gas detector.

2. When contacting the specific gas with the color-changing layer, contact the outside air with the color-changing layer so that the degree of contact with the outside air on the color-changing layer is continuously different, and observe the degree of color change of the color-changing layer due to the contact with the specific gas. Characteristic gas detection method.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION (1) Gas detection device In general, the discoloration layer in the present invention is formed by applying an ink (gas detection ink) capable of forming a coating film that changes color upon contact with a specific gas to a substrate. , Impregnated or the like, and can be appropriately formed according to the type of the specific gas.

The specific gas is not particularly limited as long as there is a gas detection ink corresponding to the gas. Therefore, for example, ozone (oxidant), nitrogen oxide (NO _x ),
Oxides of sulfur oxides (SO _x ), carbon oxides (CO, CO ₂ ), sulfur compounds (H ₂ S, CH ₃ SH), nitrogen compounds (NH ₃ ), chlorine compounds (Cl ₂ , CCl ₄ ) And various gases such as carbon compounds (CH ₄ , HCHO, CH ₃ CHO, C ₂ H ₂ ).

The substrate is not particularly limited as long as it can form a color change layer. For example, metals and alloys, wood materials, paper, ceramics, glass, concrete, plastics, fibers (nonwoven fabric, woven fabric, other fiber sheets), composite materials thereof, and the like can be used. In the present invention, in the case where the gas detection ink is directly applied to a component (for example, a container or the like) of the gas detection device itself to form the discoloration layer, the component can be a base material.

The gas detection device of the present invention has an outside air introduction section and an outside air discharge section. The outside air introduction part may have one or two or more. Similarly, one or more outside air discharge units may be provided. The configurations of the outside air introduction section and the outside air discharge section are not particularly limited as long as the discoloration layer can be prevented from being directly affected by the outside air flow. For example, an air vent provided with a windshield member such as a hood, a mesh sheet, a mesh board, or a porous material can be employed. In addition, a vent having a tapered shape toward the outside and a vent having a large number of fine pores can be used as the outside air introducing portion or the outside air discharging portion in the present invention.

As the outside air introducing section, a means for forcibly sending a certain amount of outside air can be adopted as necessary. As this means, for example, an electric fan can be used. The above-mentioned electric fan is not particularly limited as long as a constant air volume can be blown to the discoloration layer, a known electric fan can be used as it is, and a known electric fan / blower, a hair dryer, or the like, or has a function similar thereto. A gas detector can also be used, and may be appropriately selected and used according to the type, size, and the like of the gas detector of the present invention.
For example, after the electric fan is provided in the ventilation hole, the above-mentioned windshield member can be used together if necessary. Further, if necessary, the vent itself can be processed into a predetermined shape as described above.

As the outside air discharging section, means capable of forcibly discharging a certain amount of outside air can be employed as required. As this means, for example, an electric fan can be used. The above-mentioned electric fan is not particularly limited as long as a constant air volume can be blown to the discoloration layer, a known electric fan can be used as it is, and a known electric fan / blower, a hair dryer, or the like, or has a function similar thereto. A gas detector can also be used, and may be appropriately selected and used according to the type, size, and the like of the gas detector of the present invention.
For example, after the electric fan is provided in the ventilation hole, the above-mentioned windshield member can be used together if necessary. Further, if necessary, the vent itself can be processed into a predetermined shape as described above.

In the gas detection device of the present invention, the outside air and the discoloration layer are substantially isolated except for the outside air introduction section and the outside air discharge section. The form is not particularly limited as long as the discoloration layer can be prevented from being directly affected by the airflow of the outside air. For example, as shown in FIG. 1, even when the side surface (the portion corresponding to the thickness) of the color-changing layer is exposed to the outside air, the influence of the airflow of the outside air is extremely small, and such an embodiment is also included in the present invention.

The location, size, shape, and the like of the discoloration layer can be determined as appropriate in accordance with the positions of the outside air introduction section and the outside air discharge section. The means for forming (fixing) the color changing layer is not particularly limited as long as the color changing performance is not impaired. In addition to being able to be formed by directly applying the specific gas detection ink to the components of the gas detection device, the discoloration layer formed by applying or impregnating the specific gas detection ink to the base material can be formed with an adhesive tape, an adhesive, a binding device ( Screws, screws,
(For example, a stapler or a clip).

The gas detecting device of the present invention is preferably provided with a monitoring window so that the color change state of the color change layer can be recognized from the outside. Thus, the degree of color change of the color changing layer can be known without removing the color changing layer from the gas detection device. The material and shape of the monitoring window are not particularly limited as long as the degree of discoloration can be recognized from the outside. Therefore, the material may be a transparent material, and for example, an organic or inorganic material such as an acrylic resin, a celluloid resin, and glass can be used. The above material may be any of colorless and transparent, colored and transparent, translucent, etc., as long as it can be recognized from the outside. Further, in the present invention, for example, in a container type gas detection device as shown in FIG. 2, a container itself may be made of a transparent material.

Further, in the present invention, it is desirable that the color change layer is provided so that the degree of contact with the outside air is continuously different. This is particularly effective when quantitatively detecting the gas concentration. Therefore, if the degree of contact with the outside air is continuously changed in order from the end of the color changing layer to the other end, quantitative detection of the gas concentration can be performed more reliably and precisely.

The method of providing the discoloration layer so that the degree of contact with the outside air is continuously different is not particularly limited.
Basically, the outside air introduction section and the outside air discharge section may be appropriately provided so that the entire surface of the discoloration layer is not discolored at a time. For example, as shown in FIG. 1, the degree of contact with the outside air on the color changing layer is continuously different by providing an outside air introducing portion (also serving as an outside air discharging portion) so that the outside air comes into contact with the periphery of the color changing layer. Alternatively, as shown in FIG. 2, an outside air introduction portion can be provided so that the outside air comes into contact with the end portion of the discoloration layer. By installing the outside air introduction unit and the outside air discharge unit in such a state, it becomes possible to detect the specific gas qualitatively or quantitatively accurately and quickly.

(2) Gas Detection Method In the gas detection method of the present invention, when a specific gas is brought into contact with the color-change layer, the outside air is brought into contact with the color-change layer such that the degree of contact with the outside air on the color-change layer is continuously different. In addition, the degree of discoloration of the discoloration layer due to contact with a specific gas is observed. In carrying out this gas detection method, for example, the gas detection device of the present invention can be suitably used.

According to the method of the present invention, the gas concentration and the CT value (gas concentration × exposure time) can be detected more accurately and quickly. From this point, the indicator of the present invention can be used in various atmospheres such as a place where an air conditioner, a circulator and the like are used, a place where no external influence is cut off, and the like.

In the present invention, based on known data such as the relationship between the CT value and the color difference (ΔE) and the relationship between the CT value and the color gamut, the gas concentration is determined from the detected color difference and the size of the color gamut. , CT value, etc. can be qualitatively or quantitatively detected. For example, by providing a scale corresponding to the CT value along the color changing layer, the CT value can be quantitatively measured based on the size of the color changing area of the color changing layer. Further, the gas concentration or the exposure time can be measured quantitatively or qualitatively based on the obtained CT value.

(3) Ozone Detecting Ink In the present invention, when ozone (oxidant) is used as the specific gas, it is desirable to form a color change layer using the ozone detecting ink.

The ink for detecting ozone is not particularly limited as long as its color changes when the coating film comes into contact with ozone, and known inks or commercially available inks can be used.
For example, an ink using potassium iodide, a triphenylmethane-based leuco body, pn-butoxyaniline, or the like can be used. In the present invention, "discoloration"
This concept encompasses all phenomena in which the initial color (lightness, hue, etc.) changes, and includes, for example, fading, decoloring, coloring, and the like.

In particular, in the present invention, at least one of a primary amino group and a secondary amino group is used as an ozone detecting ink.
It is desirable to use an ink containing an anthraquinone dye having a kind of amino group.

The anthraquinone dye used in the present invention is
There is no particular limitation as long as it has anthraquinone as a basic skeleton and has at least one amino group of a primary amino group and a secondary amino group, and known anthraquinone-based disperse dyes can be used. The amino group may have two or more,
These may be the same or different from each other.

Examples of such anthraquinone dyes include 1,4-diaminoanthraquinone (CIDisp).
erse Violet 1), 1-amino-4-hydroxy-2-
Methoxyanthraquinone (CIDisperse Red 4), 1-
Amino-4-methylaminoanthraquinone (CIDisper
se Violet 4), 1,4-diamino-2-methoxyanthraquinone (CIDisperse Red 11), 1-amino-2
-Methylanthraquinone (CIDisperse Orange 11),
1-amino-4-hydroxyanthraquinone (CIDisp
erse Red 15), 1,4,5,8-tetraaminoanthraquinone (CIDisperse Blue 1), 1,4-diamino-5-nitroanthraquinone (CIDisperseViolet 8)
(The number in parentheses is the dye number). In addition, CISolvent Blue 14, CISolvent Blue 63,
CISolvent Violet 13, CISolventViolet 14, CIS
olvent Red 52, CISolvent Red 114, CIVat Blue 2
1, CIVat Blue 30, CIVat Violet 15, CIVat Vio
let 17, CIVat Red 19, CIVat Red 28, CIAcid B
lue 23, CIAcid Blue 80, CIAcid Violet 43, CI
Acid Violet 48, CIAcid Red 81, CIAcid Red 83,
CIReactive Blue 4, CIReactive Blue 19, CIDis
Dyes known as perse Blue 7 and the like can also be used. These anthraquinone dyes can be used alone or in combination of two or more. Among these anthraquinone dyes, CI Disperse Blue7, CI Dispere
se Violet 1 and the like are preferred. In the present invention, the detection sensitivity of ozone can be controlled by changing the type (molecular structure and the like) of these anthraquinone dyes.

In the present invention, it is more preferable that the ink containing the anthraquinone dye further contains a quaternary ammonium salt type cationic surfactant.

The quaternary ammonium salt-type cationic surfactant (hereinafter, also simply referred to as "cationic surfactant") is not particularly limited, and usually an alkyl ammonium salt can be used, which is commercially available. Goods can also be used. These can be used alone or in combination of two or more. In the present invention, more excellent ozone detection sensitivity can be obtained by using these cationic surfactants in combination with the anthraquinone dye.

Among these cationic surfactants, alkyltrimethylammonium salts, dialkyldimethylammonium salts and the like are preferable. Specifically, coconut alkyltrimethylammonium chloride, tallowalkyltrimethylammonium chloride, behenyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, lauryltrimethylammonium chloride, octadecyltrimethylammonium chloride, dioctyldimethylammonium chloride, distearyldimethylammonium chloride, chloride Alkylbenzyldimethylammonium and the like,
Particularly, lauryltrimethylammonium chloride is preferred.

In the ink of the present invention, if necessary, components used in known inks such as a resin binder, an extender, and a solvent can be appropriately compounded.

The resin binder may be appropriately selected depending on the type of the base material and the like. For example, a known resin component used for an ink composition for writing or printing can be used as it is. Specifically, for example, maleic acid resin,
Examples include amide resins, ketone resins, alkylphenol resins, rosin-modified resins, polyvinyl butyral, polyvinyl pyrrolidone, and cellulose resins.

The extender is not particularly restricted but includes, for example, bentonite, activated clay, aluminum oxide, silica gel and the like. In addition, a material known as a known extender can be used. Among them, porous ones are preferred, and silica gel is more preferred. By adding such an extender, the detection sensitivity can be mainly increased.

As the solvent that can be used in the present invention,
Any solvent can be used as long as it is a solvent used for ink compositions for printing, writing and the like. For example, various solvents such as alcohols, esters, ethers, ketones, and hydrocarbons can be used, and they may be appropriately selected according to the solubility of the dye and resin binder to be used.

These mixing ratios may be set as appropriate according to the type of the components used, the application, and the like. For example, when an ink containing the above anthraquinone dye is used as the ozone detection ink, the anthraquinone dye is usually 0.05 to 5% by weight (preferably 0.1 to 1% by weight) in the ink, and the resin binder is used. It may be adjusted to 50% by weight or less (preferably 5 to 35% by weight), 1 to 30% by weight of an extender (preferably 2 to 20% by weight), or the like.

When a cationic surfactant is further added, an anthraquinone dye is usually added in the ink at a concentration of 0.1%.
05 to 10% by weight (preferably 0.1 to 1% by weight), 0.2 to 30% by weight (preferably 0.5 to 10% by weight) of the cationic surfactant,
0% by weight or less (preferably 5-35% by weight), extender 1
It may be adjusted to 30% by weight (preferably 2 to 20% by weight) or the like.

These components may be blended simultaneously or sequentially and uniformly mixed using a known stirrer such as a homogenizer or a dissolver. For example, an anthraquinone-based dye, a cationic surfactant, a resin-based binder, an extender, and the like may be mixed in a solvent in order, followed by mixing and stirring.

The formation of the discoloration layer in the present invention can be carried out by using a known printing method such as silk screen printing, gravure printing, offset printing, letterpress printing, flexographic printing, etc., using each ink. The order of printing the color-change layer and the non-color-change layer is not particularly limited, and may be appropriately selected according to the design to be printed. Alternatively, each layer can be formed by immersing the base material in the ink. It is particularly suitable for a material into which the ink penetrates, such as paper and nonwoven fabric.

[0046]

According to the gas detecting apparatus and the gas detecting method of the present invention, the specific gas can be detected more accurately because the gas detecting apparatus and the gas detecting method are in contact with the specific gas almost without being affected by the outside air. it can. Further, the gas detection speed can be increased by forcibly sending or discharging the outside air.

Further, when an ozone detecting ink containing a specific anthraquinone dye is used in the formation of the color-change layer, low-concentration ozone (for example, an ozone concentration of 0.05 p
pm) can be reliably detected, and an excellent sensitivity not available in the prior art can be achieved.

[0048]

EXAMPLES Examples and comparative examples are shown below to further clarify the features of the present invention. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG. 1 shows a disk type gas detector as an example of the gas detector of the present invention. In this disc-shaped device, a transparent material is brought into contact with the color changing layer as a monitoring window, a porous substrate is brought into contact with the other surface of the color changing layer, and the other surface of the porous substrate is isolated from the outside air. In addition, the gas detection device has a monitoring window, a color change layer, and a porous substrate connected via a support.

More specifically, a transparent substrate (1), a discoloration layer (2) in which a substrate (paper) is impregnated with a gas detection ink,
A porous substrate (3) and a gas impermeable material (4) are laminated, and each is connected via a support (5). The porous base material has open pores on the outer edge side surface and has a communication hole inside so that a specific gas can be transmitted.

In this apparatus, the porous substrate corresponds to the air volume adjusting means, and each open hole also serves as an outside air introduction section and an outside air discharge section. The gas impermeable material is not particularly limited as long as the back surface of the porous substrate does not come into direct contact with the specific gas, and may be, for example, a resin film, a metal film, or the like, or a resin-coated gas. Impermeableness can also be imparted.

In FIG. 1, each member has a disk shape, but may have another shape (square, rectangle, ellipse, triangle, polygon, etc.). Further, the size of each member may be the same as or larger or smaller than the color changing layer. Normally, they should be the same size. The porous substrate is not particularly limited as long as it is gas-permeable, and for example, a porous material such as various inorganic materials and resin materials may be appropriately selected.

When this device is installed in an atmosphere containing a specific gas, the outside air enters through the pores (open pores) on the side surface of the outer edge of the porous substrate, and comes into contact with the specific gas from outside the disc-shaped discoloration layer. Discoloration starts from the circumference to the center of the discoloration layer. The invading outside air passes through the pores and is discharged from other pores.

Embodiment 2 FIG. 2 shows a container type gas detector. In this device, a color change layer is formed on at least a part of the inner wall surface of the container provided with the electric fan on at least one of the outside air introduction portion and the outside air discharge portion so that the color change state of the color change layer can be recognized from the outside. This is a gas detection device provided with a monitoring window in a container.

More specifically, a discoloration layer (1) is formed on one surface of the rectangular container (2), and a ventilation port (3) and an electric fan (4) are provided as an outside air introduction portion, A slit-shaped vent (5) is provided as an outside air discharge part.
In addition, a monitoring window (6) is provided on a surface opposite to the surface on which the discoloration layer is formed. The electric fan is installed slightly downward so that the outside air comes into contact in order from the end of the discoloration layer.

Although the container of this apparatus is rectangular, the present invention is not limited to a rectangular, and a container having a known form such as a cube, a rectangular parallelepiped, or a cylindrical body can be used. The material of the container may be appropriately selected according to the measurement purpose, the measurement environment, and the like. For example, if a transparent material such as an acrylic resin, a celluloid resin, or glass is used, the color change range, color difference, and the like in the color change layer can be easily recognized from the outside.

The outside air is forcibly introduced by the electric fan, and the specific gas comes into contact in order from the end of the color changing layer, and the color changing portion gradually spreads toward the slit-shaped vent. Thus, the specific gas (concentration) can be detected quickly and reliably.

Example 3 An ozone detecting device was prepared in the same manner as in Example 1, except that an ozone detecting ink was used to form the color changing layer. Ozone detection was performed using this device.

(1) Preparation of ink for detecting ozone and formation of discoloration layer First, 0.20 parts by weight of an anthraquinone-based disperse dye (“Miketone Fast Red Violet R” manufactured by Mitsui BASF) and ethyl cellulose-based resin as a resin-based binder (“Ethocel 10” manufactured by Dow Chemical Company) 7.35 parts by weight, silica gel (“Aerosil R-972” manufactured by Nippon Aerosil Co., Ltd.) 9.80 parts by weight, cocoalkyltrimethylammonium chloride (“CA-
2.96 parts by weight of 2150 (manufactured by NIKKOL) and 80.69 parts by weight of ethyl cellosolve ("Shifosol MG" manufactured by Nippon Shokubai Co., Ltd.) as a solvent were uniformly mixed with a stirrer to prepare an ozone detection ink.

This ozone detecting ink was applied to the entire surface of a disk-shaped substrate (Kent paper) and dried to form a color-change layer. In this ozone detection device, an acrylic resin was used as a transparent substrate and a support, and foamed polyurethane was used as a porous substrate.

(2) Ozone detection The above-mentioned ozone detection device was left in an ozone atmosphere of 0.3 ppm for about 15 minutes. As a result, it was visually observed that the color of the color-changing layer was faded or erased in order from the outer periphery to the center of the color-changing layer.

Example 4 0.25 parts by weight of an anthraquinone-based disperse dye (“Miketone Fast Red Violet R” manufactured by Mitsui BASF)
2.25 parts by weight of an ethylcellulose-based resin (“Ethocel 10” manufactured by Dow Chemical Co., Ltd.) and a maleic acid resin (“Marquid 33” manufactured by Arakawa Chemical Co., Ltd.)
13 parts by weight, 6.25 parts by weight of silica gel as a bulking agent,
In addition, 84.12 parts by weight of ethyl cellosolve as a solvent were uniformly mixed to prepare an ink for detecting ozone. An ozone detector was prepared in the same manner as in Example 4 except that this ink was used, and the ozone was detected by this. As a result, it was visually observed that the color of the color-changing layer was faded or erased in order from the outer periphery to the center of the color-changing layer.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example (disk type) of a gas detection device of the present invention.

FIG. 2 is a view showing an example (container type) of the gas detection device of the present invention.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G042 AA01 BA02 BB10 BE03 CA01 CB01 DA08 EA20 FA11 FA17 FB05 HA07 2G054 AA01 AB10 BA10 BB06 CA08 CB02 CE01 EA06 EA07 EB20 FA01 FA15 GB04 GE01

Claims (12)

[Claims] 1. A discoloring layer which changes color by a specific gas, an external air introducing portion for introducing outside air to the discoloring layer, and an external air discharging portion for discharging the introduced external air, excluding the external air introducing portion and the external air discharging portion. A gas detection device, wherein the outside air and the discoloration layer are substantially isolated from each other. 2. The gas detecting device according to claim 1, further comprising a monitoring window so that the color change state of the color change layer can be recognized from outside. 3. A discoloration layer is formed on at least a part of an inner wall surface of a container provided with an electric fan on at least one of an outside air introduction portion and an outside air discharge portion so that a discoloration state of the discoloration layer can be recognized from outside. 2. A monitoring window is provided on the container.
The gas detection device according to any one of the preceding claims. 4. A transparent material is brought into contact with the color-changing layer as a monitoring window, a porous substrate is brought into contact with the other surface of the color-changing layer, and the other surface of the porous substrate is isolated from the outside air. The gas detection device according to claim 1, wherein the monitoring window, the color changing layer, and the porous substrate are connected via a support. 5. A monitoring window, wherein a transparent member is in contact with the color-changing layer, and a gap is formed between the transparent member and the color-changing layer, and the monitoring window and the color-changing layer are connected via a support. The gas detection device according to claim 1, wherein 6. The gas detection device according to claim 1, wherein a color change layer is provided so that the degree of contact with the outside air is continuously different. 7. The gas detector according to claim 1, wherein the color change layer is formed by applying or impregnating the substrate with an ink for detecting ozone. 8. The gas detection device according to claim 7, wherein the ozone detection ink contains an anthraquinone dye having at least one amino group of a primary amino group and a secondary amino group. 9. The ink for detecting ozone according to claim 8, further comprising a quaternary ammonium salt type cationic surfactant.
The gas detection device according to any one of the preceding claims. 10. The gas detector according to claim 9, wherein the quaternary ammonium salt type cationic surfactant is an alkyltrimethylammonium salt. 11. When contacting a specific gas with a color-changing layer,
A gas detection method comprising: bringing outside air into contact with a color change layer such that the degree of contact with the outside air on the color change layer is continuously different; and observing the degree of color change of the color change layer due to contact with a specific gas. 12. The gas detection method according to claim 11, wherein the CT value is obtained from a color difference or a color change range due to the color change of the color change layer.