JP2008032689A - Laminate type oxidizing-gas indicator and method of detecting oxidizing gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxidizing-gas indicator which is thin and can be relatively easily managed/stored before use. <P>SOLUTION: The oxidizing-gas indicator is a laminate comprising a color-changeable sheet and transparent sheets, and is characterized in that (1) the color-changeable sheet and the transparent sheets are superposed in such a state that the color-changeable sheet is sandwiched between the transparent sheets, (2) the color-changeable sheet is blocked from the surrounding air by the transparent sheets, and (3) the color-changeable sheet is one comprising a fibrous substrate and, formed on part or all of the surfaces thereof, a color-changeable layer which changes in color upon contact with an oxidizing gas. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel laminate-type oxidizing gas indicator and an oxidizing gas detection method.

  Detection of oxidizing gas including ozone gas is used in various fields. For example, when sterilizing an object to be processed with an oxidizing gas (for example, ozone gas), there is a method using a gas detection indicator as a method for confirming whether the object to be processed has been sterilized. That is, it is possible to confirm that the object to be processed has been exposed to the oxidizing gas by providing a gas detection indicator on the object to be processed or the sterilization apparatus and examining the discoloration state.

As a gas detection indicator, a detection method using a small indicator is particularly in the light of its simplicity and economy. For example, the gas indicator main body is formed in a substantially plate shape and a passage for introducing a specific gas to be detected is formed therein, and an indicator layer that changes color by reacting with the specific gas along the passage is formed on the inner wall of the passage. A high-sensitivity gas indicator or the like characterized by forming an opening of a predetermined area that allows a specific gas to immediately contact the indicator body and providing an indicator layer in the opening is known ( Patent Document 1 and Patent Document 2). Further, for example, a gas detection device in which a color-changing gas detection material is loaded in a container, and has a gas passage space from the opening to the bottom of the container, and the cross-sectional area of the container parallel to the opening is from the opening to the bottom There is known a gas detection device having a container shape that gradually decreases over a portion (Patent Document 3).
JP-A-8-122318 Japanese Patent Laid-Open No. 7-49342 JP 2000-303617 A

  However, in the conventional indicator, the device is relatively large, and further downsizing and thinning are required. Moreover, the conventional product must be strictly managed and stored so as not to change its color before use, and there is room for improvement in this respect.

  Accordingly, a main object of the present invention is to provide an oxidizing gas indicator that is thin and relatively easy to manage and store before use.

  As a result of intensive studies in view of the above-mentioned problems of the prior art, the present inventor has found that an indicator having a specific structure can achieve the above-mentioned purpose, and has completed the present invention.

That is, the present invention relates to the following laminate type oxidizing gas indicator and oxidizing gas detection method.
1. A laminate comprising a discoloring sheet and a transparent sheet,
(1) The color changing sheet and the transparent sheet are laminated in such a state that the color changing sheet is sandwiched between the transparent sheets,
(2) The discoloration sheet is blocked from contact with the outside air by the transparent sheet,
(3) The color-changing sheet is a sheet in which a color-changing layer that changes color by contacting an oxidizing gas is formed on a part or all of the fibrous base material.
A laminate-type oxidizing gas indicator characterized by that.
2. The laminate-type oxidizing gas indicator according to Item 1, wherein a spacer is disposed between the discoloring sheet and the transparent sheet.
3. Item 3. The laminate type oxidizing gas indicator according to Item 2, wherein the spacer is disposed between the color changing layer and the transparent sheet over the length direction of the color changing layer.
4). Item 4. The laminated oxidizing gas indicator according to Item 2 or 3, wherein an oxidizing gas passage is formed by the discoloration layer, the transparent sheet, and the spacer.
5. Item 1-5, wherein the discoloration layer is formed of an ink composition containing at least one of an anthraquinone dye, an azo dye, an oxazine dye, a thiazine dye, a methine dye, and a triarylmethane dye. The laminate type oxidizing gas indicator according to any one of the above.
6). Item 6. The laminate type oxidizing gas indicator according to Item 5, wherein the ink composition further contains at least one of a surfactant, a filler, and a binder.
7). The laminate-type oxidizing gas indicator according to any one of Items 1 to 6, wherein the discoloring sheet is rectangular.
8). The laminate-type oxidizing gas indicator according to any one of Items 1 to 7, wherein a plurality of discoloration layers are formed on the fibrous base material.
9. The laminate mold according to any one of Items 1 to 8, wherein a CT value (oxidizing gas concentration × exposure time) corresponding to the color change region of the color change layer is written on the color change sheet and / or the transparent sheet. Oxidizing gas indicator.
10. A method for detecting an oxidizing gas using the laminate type oxidizing gas indicator according to any one of Items 1 to 9,
(1) A step of cutting the end portion of the laminate type oxidizing gas indicator to expose the cross section of the discolorable sheet in an oxidizing gas atmosphere,
(2) A method for detecting an oxidizing gas including a step of confirming a color change state of a color change sheet.
11. A method of measuring a CT value by an oxidizing gas using the laminate type oxidizing gas indicator according to any one of Items 1 to 9,
(1) A step of cutting the end portion of the laminate type oxidizing gas indicator to expose the cross section of the discolorable sheet in an oxidizing gas atmosphere,
(2) a step of confirming the color change state of the color change sheet,
(3) a step of obtaining a CT value from the relationship between the CT value prepared in advance and the discoloration state;
Method for detecting oxidizing gas containing

  According to the laminate type oxidizing gas indicator of the present invention, since it is composed of a laminate of a color changing sheet and a transparent sheet, a small and thin indicator can be provided. In particular, it is possible to provide a thin indicator that has not existed so far, with a thickness of 3 mm or less (particularly 0.5 to 2 mm).

  Moreover, since the indicator of the present invention is placed in a state in which the color-changing sheet is sealed with a transparent sheet before use, it can be stored easily and reliably. Unlike conventional indicators, it does not change color during storage.

  Furthermore, the indicator of the present invention can be used to detect oxidizing gases of various concentrations by adjusting the degree of adhesion between the color changing sheet and the transparent sheet, the size of the gap, and the like. In particular, it is useful for detecting an oxidizing gas having a high concentration of 100 to 1000 ppm. In addition, as a CT value, it is possible to detect a relatively large region of usually 10,000 to 300,000 ppm · min.

  In the present invention, the passage of the oxidizing gas can be formed by interposing a spacer between the discoloration layer and the transparent sheet (in some cases, removing the spacer intervened during production in use). As a result, the oxidizing gas can be circulated more reliably to the back of the indicator. As a result, the color change width can be increased to further increase the sensitivity.

  The laminate type oxidizing gas indicator of the present invention can be widely used for applications in the medical field, food field, precision instrument field, life hygiene field, electrical appliance field, and the like.

1. Laminate-type oxidizing gas indicator The laminate-type oxidizing gas indicator of the present invention is a laminate comprising a discoloring sheet and a transparent sheet,
(1) The color changing sheet and the transparent sheet are laminated in such a state that the color changing sheet is sandwiched between the transparent sheets,
(2) The discoloration sheet is blocked from contact with the outside air by the transparent sheet,
(3) The color-changing sheet is a sheet in which a color-changing layer that changes color by contacting an oxidizing gas is formed on a part or all of the fibrous base material.
It is characterized by that.

  The laminate type oxidizing gas indicator of the present invention will be described with reference to the drawings. FIG. 1 shows a plan view of an example of the indicator of the present invention. Moreover, the A-A 'cross section is shown in FIG.

  As shown in FIG. 2, the color-changing sheet 1 is laminated in a state where it is sandwiched between the transparent sheets 2 and 2. That is, the transparent sheet has an area larger than that of the color-changing sheet, and the transparent sheets are in a state of being laminated and adhered to each other in the peripheral region of the color-changing sheet. In FIG. 2, the boundary line 3 between the transparent sheets exists, but may be integrally formed by heat fusion or the like. As described above, since the transparent sheet is in close contact with the peripheral region of the color changing sheet, the color changing sheet is in a state in which the contact with the outside air is blocked. Thereby, discoloration before use can be effectively prevented.

  The present invention is not limited to the structure of FIG. 1 as long as it has the features (1) to (3). For example, as shown in FIG. 7, a disk-shaped discoloration sheet (not shown) may be sandwiched between two disk-shaped transparent sheets 2. In this case, the discoloration layer can be exposed to the oxidizing gas by opening a hole penetrating to the discoloration layer in the X portion. In this case, the color change from X to a concentric circle occurs.

  The color changing sheet and the transparent sheet may be in close contact (adhesion) or may not be in close contact. Further, there may be a gap between the color changing sheet and the transparent sheet, or there may be no gap. In the gap, for example, a transparent sheet or other resin sheet processed into a rod shape or a strip shape, a wood material processed into a rod shape, or the like may be interposed as a spacer. The passage of the oxidizing gas can be formed by interposing the spacer. FIG. 4 shows a cross-sectional view when a spacer is arranged. In FIG. 4, the spacer 4 is disposed on the color changing layer 3. At this time, as shown in FIG. 5, the passage 5 can be efficiently formed if the transparent sheet 2 is designed not to follow the corner 5 completely.

  In the case of using a spacer, it is particularly preferable that the spacer is disposed across the length direction of the color changing layer between the color changing layer and the transparent sheet. In FIG. 6, the spacer 4 is designed to have substantially the same length as the length of the color changing layer 3.

  When using the indicator of the present invention, the spacer may be used with it attached, or may be used after the spacer is removed. When the spacer is removed, a larger passage can be formed. The spacer can be removed by pulling out the end of the laminate type oxidizing gas indicator during use and exposing the cross section of the discolorable sheet in an oxidizing gas atmosphere.

  When a gap (space) is provided between the color changing sheet and the transparent sheet, the distance between the two may be usually 1 mm or less (particularly 0 to 1 mm).

  In the present invention, even if there is no gap (space) between the color-changing sheet and the transparent sheet, the oxidizing gas permeates through the fibrous base material, so that a desired detection effect is obtained. be able to.

  The presence / absence of adhesion between the color-changing sheet and the transparent sheet may be appropriately designed depending on the concentration of the oxidizing gas to be detected, CT value (oxidizing gas concentration × oxidizing gas exposure time), and the like. If adhesion is required, a heat-sealable transparent sheet or the like may be used.

  The transparent sheet (film) is not limited as long as it is transparent and can be laminated. For example, a transparent resin such as vinyl chloride resin, polyethylene terephthalate (PET), or acrylic resin can be suitably used.

  The color-changing sheet is a sheet in which a color-changing layer that changes color with an oxidizing gas is formed on a fibrous base material.

  The fibrous base material may be any material that can support the discoloration layer, and examples thereof include papers (Kent paper, plain paper, drawing paper, Japanese paper, high-quality paper, etc.), non-woven fabric, and woven fabric.

  The discoloration layer is not limited as long as it is discolored (including decoloration, fading, etc.) by contact with an oxidizing gas, but in particular, anthraquinone dyes, azo dyes, oxazine dyes, thiazine dyes And an ink composition containing at least one methine dye and triarylmethane dye (color-changing dye).

  The anthraquinone dye is not particularly limited 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 a known anthraquinone disperse dye or the like can also be used. The amino group may have two or more, and these may be the same or different from each other. Examples of such anthraquinone dyes include 1,4-diaminoanthraquinone (CIDisperse Violet 1), 1-amino-4-hydroxy-2-methoxyanthraquinone (CIDisperse Red 4), 1-amino-4-methylamino Anthraquinone (CIDisperse Violet 4), 1,4-diamino-2-methoxyanthraquinone (CIDisperse Red 11), 1-amino-2-methylanthraquinone (CIDisperseOrange 11), 1-amino-4-hydroxyanthraquinone (CIDisperse) Red15), 1,4,5,8-tetraaminoanthraquinone (CIDisperse Blue 1), 1,4-diamino-5-nitroanthraquinone (CIDisperse Violet 8) and the like (dye number in parentheses) . CISolvent Blue 14, CISolvent Blue 63, CISolvent Violet 13, CISolvent Violet 14, CISolvent Red 52, CISolvent Red 114, CIVat Blue 21, CIVat Blue 30, CIVat Violet 15, CIVat Violet 17, CIVat Red 19, CIVat Red 28, CIAcid Blue 23, CIAcid Blue 80, CIAcid Violet 43, CIAcid Violet48, CIAcid Red 81, CIAcid Red 83, CIReactive Blue 4, CIReactiveBlue 19, A dye known as CIDisperse Blue 7 can also be used. These anthraquinone dyes can be used alone or in combination of two or more. Among these anthraquinone dyes, C.I Disperse Blue 7, C.I Disperse Violet 1 and the like are preferable. In the present invention, the detection sensitivity of ozone can also be controlled by changing the type (molecular structure, etc.) of these anthraquinone dyes.

  The azo dye is not limited as long as it has an azo group —N═N— as a chromophore. Examples thereof include monoazo dyes, polyazo dyes, metal complex azo dyes, stilbene azo dyes, thiazole azo dyes, and the like. More specifically, the dye numbers indicate CIDisperse Red 13, CIDisperse Red 52, CIDisperse Violet 24, CIDisperse Blue, 44, CIDisperse Red 58, CIDisperse Red 88, CIDisperse Yellow 23, CIDisperse Orange 1, CIdisperse Orange 5, CISolvent Red 1, CISolvent Red 3, CISolvent Red 23, and the like. These can be used alone or in combination of two or more.

  The methine dye may be a dye having a methine group. Therefore, in the present invention, polymethine dyes, cyanine dyes and the like are also included in the methine dyes. These can be appropriately selected from known or commercially available methine dyes. Specifically, CIBasic Red 12, CIBasic Red 13, CIBasic Red 14, CIBasic Red 15, CIBasic Red 27, CIBasic Red 35, CIBasic Red 36, CIBasic Red 37, CIBasic Red 45, CIBasic Red 48, CIBasic Yellow 11, CIBasic Yellow 12, CIBasic Yellow 13, CIBasic Yellow 14, CIBasic Yellow 21, CIBasic Yellow 22, CIBasic Yellow 23, CIBasic Yellow 24, CIBasic Violet 7, CIBasic Violet 15, CIBasic Violet 16, CIBasic Violet 20, CIBasic Violet 21, CIBasic Violet 39, CIBasic Blue 62, CIBasic Blue 63, and the like. These can be used alone or in combination of two or more.

  The triarylmethane dye is not limited, and known or commercially available dyes can be used. For example, CIBasic Blue 1, CIBasic Blue 26, CIBasic Blue 5, CIBasic Blue 8, CIBasic Green 1, CIBasic Red 9, CIBasic Violet 12, CIBasic Violet 14, CIBasic Violet 3, CISolvent Green 15, CISolvent Violet 8, etc. These can be used alone or in combination of two or more. Among these triarylmethane dyes, C.I.Solvent Violet 8, C.I.Basic Green 1, C.I.Basic Red 9, C.I.Basic Blue 1, and the like can be suitably used.

  The thiazine dye is not particularly limited and can be selected from known or commercially available ones. Examples thereof include C.I.Basic Blue 9, C.I.Basic Blue 25, C.I.Basic Blue 24, C.I.Basic Blue 17, C.I.Basic Green 5, C.I.Solvent Blue 8, and the like. These can be used alone or in combination of two or more. Among these thiazine dyes, C.I.Basic Blue 9 and the like can be suitably used.

  The oxazine-based dye is not particularly limited as long as it has at least one oxazine ring represented by the following formulas (I) to (III). For example, a monooxazine dye having one oxazine ring and a dioxazine dye having two oxazine rings are also included.

  In the present invention, any of a basic dye having at least one substituted or unsubstituted amino group as an auxiliary color group, a chromium mordant dye having an OH group, a COOH group, or the like as a substituent can be used. .

  These oxazine dyes can be used alone or in combination of two or more. These may be known or commercially available. In terms of dye numbers, it is particularly desirable to use oxazine dyes such as C.I. Basic Blue 3, C.I. Basic Blue 12, C.I. Basic Blue 6, C.I. Basic Blue 10, and C.I. Basic Blue 96. Furthermore, C.I. Basic Blue 3 etc. are more desirable.

  In the present invention, the content of these color-changing dyes is not limited, but generally it is preferably about 0.1 to 10% by weight, particularly 1 to 5% by weight in the ink composition.

  In the present invention, it is more preferable that the ink composition further contains a quaternary ammonium salt type cationic surfactant as required.

  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 also a commercially available product. it can. Moreover, these can be used by 1 type (s) or 2 or more types. In the present invention, a better ozone detection sensitivity can be obtained by using these cationic surfactants in combination with the anthraquinone dyes.

  Among these cationic surfactants, alkyltrimethylammonium salts and dialkyldimethylammonium salts are preferable. Specifically, palm alkyltrimethylammonium chloride, tallow alkyltrimethylammonium chloride, behenyltrimethylammonium chloride, hexadecyltrimethylammonium chloride, lauryltrimethylammonium chloride, octadecyltrimethylammonium chloride, dioctyldimethylammonium chloride, distearyldimethylammonium chloride, chloride Examples thereof include alkylbenzyldimethylammonium, and lauryltrimethylammonium chloride is particularly preferable.

  The content of the cationic surfactant is generally about 0.1 to 5% by weight, particularly preferably 0.1 to 2% by weight in the ink composition.

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

  The resin binder may be appropriately selected according to the type of the substrate and the like. For example, known resin components used in ink compositions for writing and printing can be used as they are. Specific examples include maleic acid resins, amide resins, ketone resins, alkylphenol resins, rosin-modified resins, polyvinyl butyral, polyvinyl pyrrolidone, cellulose resins, acrylic resins, vinyl acetate resins, and the like.

  The content of the resin binder is generally about 1 to 35% by weight, particularly 5 to 20% by weight in the ink composition.

  The extender is not particularly limited, and examples thereof include bentonite, activated clay, aluminum oxide, silica gel and the like. In addition, materials known as known extender pigments can be used. Among these, a porous thing is preferable and especially a silica gel is more preferable. By adding such a bulking agent, detection sensitivity can be mainly increased.

  The content of the extender is generally about 1 to 20% by weight, particularly 5 to 15% by weight in the ink composition.

  As the solvent that can be used in the present invention, any solvent that is usually used in ink compositions for printing, writing, etc. can be used. For example, various solvents such as alcohol-based, ester-based, ether-based, ketone-based and hydrocarbon-based solvents can be used, and may be appropriately selected according to the solubility of the dye used and the resin-based binder.

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

  The shape, formation pattern, size, and the like of the color changing layer can be appropriately determined according to the use, purpose of use, type of target oxidizing gas, and the like.

  As the shape, for example, a rectangle as shown in FIG. 1 can be preferably adopted. Specifically, a rectangle having a short side of about 5 to 15 mm and a long side of 50 to 100 mm can be exemplified. The long side can be appropriately changed depending on the CT value to be measured. By making the shape rectangular, the end of the indicator is cut perpendicularly to the long side as shown in FIG. 1 to form an opening (AA ′ cross section), and from the opening to the long side, the oxidizing property is formed. Gas can enter.

  As for the formation pattern of the discoloration layer, it is possible to form the discoloration layer on the entire surface of the fibrous base material as shown in FIG. 1, but in addition, a plurality of isolated discoloration layers may be formed. For example, as shown in FIG. 3, a plurality of discoloration layers can be formed on the fibrous base material 1 in a spot shape. In this case, the discoloration layer 1d may be formed from the circular discoloration layer 1a in the order from the opening. The intervals between the color changing layers may be equal, or may be formed so that the intervals gradually become smaller or larger.

  The oxidizing gas targeted by the laminate type oxidizing gas indicator of the present invention is not particularly limited, and is suitably used, for example, for ozone gas, hydrogen peroxide gas, ethylene oxide gas, nitrogen oxide gas, sulfur oxide gas, and the like. be able to. Moreover, although the density | concentration of the oxidizing gas used as application object is based also on the kind etc. of oxidizing gas, generally it is about 0.1-500 ppm, Preferably it is 500-3000 ppm. As a range of measurable CT value (oxidizing gas concentration × exposure time), about 10,000 to 300,000 ppm · min is usually preferable.

2. TECHNICAL FIELD The present invention is a method for detecting an oxidizing gas using the laminate type oxidizing gas indicator, wherein (1) the end of the laminate type oxidizing gas indicator is cut and a cross section of the discoloring sheet is taken. The method includes a step of exposing to an oxidizing gas atmosphere, and (2) a method for detecting an oxidizing gas (first method) including a step of confirming a discoloration state of the discoloring sheet.

  The present invention also relates to a method for measuring a CT value by an oxidizing gas using the laminate type oxidizing gas indicator, wherein (1) the end of the laminated type oxidizing gas indicator is cut and a cross section of the discoloring sheet is taken. A step of exposing to an oxidizing gas atmosphere, (2) a step of confirming the discoloration state of the discoloring sheet, and (3) a step of obtaining a CT value from the relationship between the CT value prepared in advance and the discoloration state A detection method (second method) is included.

  In both the first method and the second method, the end portion of the laminate-type oxidizing gas indicator is cut to expose the cross section of the color changing sheet in an oxidizing gas atmosphere. That is, it is possible to detect the oxidizing gas by cutting the end portion of the indicator during use and bringing the cross section of the color changing sheet into contact with the oxidizing gas. For example, by cutting A-A ′ in FIG. 1 with a cutter knife, scissors or the like, an opening through which the oxidizing gas enters the indicator (the right portion in FIG. 1 is used as an indicator) is provided.

  In the first method, an oxidizing gas can be detected. In the indicator placed in an oxidizing gas atmosphere, when the oxidizing gas starts to enter from the opening, the color gradually changes from the portion near the opening of the discoloration layer. By detecting the presence or absence of the color change, the oxidizing gas can be detected.

  Further, the second method can also perform quantitative measurement. The degree of discoloration (area) gradually increases from the opening as the CT value increases. Therefore, by examining the relationship between the CT value and the color change region in advance, it is possible to quantitatively measure the CT value by looking at the color change region when the oxidizing gas is actually detected.

3. Manufacturing method of laminate type oxidizing gas indicator The manufacturing method of the indicator of the present invention is not particularly limited. For example, 1) a process for producing a color-changing sheet by forming a color-changing layer on a fibrous base material (color-changing sheet production process), 2) between two transparent sheets having a larger area than the color-changing sheet It can be suitably manufactured by a method including a step of laminating a discoloring sheet (lamination step) and 3) a step of closely adhering the portions where the transparent sheets are laminated (contact step).

  In the color-changing sheet production step, a color-changing sheet is produced by forming a color-changing layer on the fibrous base material. The discoloration layer can be formed by forming a coating film from the discolorable ink composition. The method for forming the coating film may be, for example, a method using printing (screen printing or the like), or a coating method using brush coating, spraying, rollers, or the like. In this case, the discoloration layer may be formed on the entire surface of the fibrous base material, or may be formed on a part thereof.

  In the laminating step, the color change sheet is laminated between two transparent sheets having a larger area than the color change sheet. For example, as shown in FIG. 1, the transparent sheets may be arranged so as to ensure a region (close contact) where the transparent sheets are directly laminated.

  In the adhesion step, the portions where the transparent sheets are laminated are bonded. The bonding method is not particularly limited, and for example, a method using heat fusion, a method using an adhesive, or the like can be employed.

  The present invention will be specifically described by the following examples. However, the present invention is not limited to the contents of the examples.

Example 1
A laminate type indicator as shown in FIG. 1 was produced. The components shown in Table 1 were uniformly mixed to prepare an ink. The obtained ink was screen-printed on the entire surface of one side of Kent paper (size: about 10 mm × about 50 mm) to produce a laminate 1 in which a discoloration layer (printing layer) was formed on Kent paper. The laminate was sandwiched between two OHP sheets 2 (colorless and transparent, no adhesion) (size: about 25 mm × about 65 mm) and laminated to obtain a laminate type indicator. The thickness of the obtained indicator was about 400 μm.

  The contents of each component in Table 1 are as follows.

C. I. b. red 13: methine dye butyl cellosolve: solvent microlith green GA: non-color-changing dye, manufactured by Ciba Specialty Chemicals Jonkrill 690: manufactured by Johnson Polymer, styrene acrylic acid resin, nitrified cotton HIG1 / 2: manufactured by Daicel Chemical Industries, nitrocellulose Aerosil R -972: Silica gel, manufactured by Nippon Aerosil Co., Ltd. Test Example 1
CT values (ozone concentration × exposure time) were measured using the indicators obtained in the examples.

  The broken line portion (A-A ′) in FIG. 1 was cut with a cutter knife so that at least the cross section of the laminate was in contact with the outside air, and then an ozone indicator was immediately placed in an ozone gas atmosphere having an ozone concentration of 1000 ppm. The discoloration layer on the laminate changed from purple to green by touching ozone gas. The CT value and the discolored part (distance from the broken line part) were measured. The results are shown in Table 2.

  From the results in Table 2, it can be seen that the distance from the broken line increases as the CT value increases. Thus, it can be seen that the CT value can be read quantitatively if a scale is provided on the print sheet in advance.

Example 2
An indicator was produced in the same manner as in Example 1 except that a resin square (2 mm × 2 mm × 50 mm) was interposed between the discoloration layer and the transparent sheet when the indicator was manufactured.

Example 3
An indicator was produced in the same manner as in Example 1 except that a resin square (0.8 mm × 0.8 mm × 50 mm) was interposed between the discoloration layer and the transparent sheet at the time of manufacturing the indicator.

Test example 2
The color change rate by the ozone gas of the indicator obtained in Examples 1-3 was investigated. The measurement method was the same as in Test Example 1. The results are shown in Table 3.

  As is clear from Table 3, in the range of a constant CT value (10000 to 50000 ppm · min), Example 3 had the fastest color change rate and Example 1 had the slowest rate. Thus, it can be seen that the discoloration speed can be freely controlled by changing the size of the spacer.

The top view of the laminate type indicator produced in the Example is shown. Sectional drawing of the laminate type indicator produced in the Example is shown. Another embodiment (plan view) of the laminate type indicator of the present invention is shown. Sectional drawing of the laminate type indicator which has arranged the spacer is shown. The state where the path of the oxidizing gas is formed by the spacer, the color changing layer and the transparent sheet is shown. The top view of the laminate type indicator which has arranged the spacer is shown. An embodiment (plan view) of a disk-shaped laminate type indicator of the present invention is shown.

Claims (11)

A laminate comprising a discoloring sheet and a transparent sheet,
(1) The color changing sheet and the transparent sheet are laminated in such a state that the color changing sheet is sandwiched between the transparent sheets,
(2) The discoloration sheet is blocked from contact with the outside air by the transparent sheet,
(3) The color-changing sheet is a sheet in which a color-changing layer that changes color by contacting an oxidizing gas is formed on a part or all of the fibrous base material.
A laminate-type oxidizing gas indicator characterized by that. The laminate type oxidizing gas indicator according to claim 1, wherein a spacer is disposed between the discoloring sheet and the transparent sheet. The laminate type oxidizing gas indicator according to claim 2, wherein the spacer is disposed between the color changing layer and the transparent sheet over the length direction of the color changing layer. The laminate type oxidizing gas indicator according to claim 2 or 3, wherein an oxidizing gas passage is formed by the discoloration layer, the transparent sheet and the spacer. The discoloration layer is formed of an ink composition containing at least one of an anthraquinone dye, an azo dye, an oxazine dye, a thiazine dye, a methine dye, and a triarylmethane dye. The laminate type oxidizing gas indicator according to any one of the above. The laminate type oxidizing gas indicator according to claim 5, wherein the ink composition further contains at least one of a surfactant, a filler, and a binder. The laminate type oxidizing gas indicator according to any one of claims 1 to 6, wherein the discoloring sheet is rectangular. The laminate type oxidizing gas indicator according to any one of claims 1 to 7, wherein a plurality of discoloration layers are formed on the fibrous base material. The laminate mold according to any one of claims 1 to 8, wherein a CT value (oxidizing gas concentration x exposure time) corresponding to the color change region of the color change layer is written on the color change sheet and / or the transparent sheet. Oxidizing gas indicator. A method for detecting an oxidizing gas using the laminate-type oxidizing gas indicator according to any one of claims 1 to 9,
(1) A step of cutting the end portion of the laminate type oxidizing gas indicator to expose the cross section of the discolorable sheet in an oxidizing gas atmosphere,
(2) An oxidizing gas detection method including a step of confirming a discoloration state of the discoloration sheet. A method of measuring a CT value by an oxidizing gas using the laminate type oxidizing gas indicator according to any one of claims 1 to 9,
(1) A step of cutting the end portion of the laminate type oxidizing gas indicator to expose the cross section of the discolorable sheet in an oxidizing gas atmosphere,
(2) a step of confirming the color change state of the color change sheet,
(3) a step of obtaining a CT value from the relationship between the CT value prepared in advance and the discoloration state;
Method for detecting oxidizing gas containing