Carbon dioxide gas detector

Abstract

This carbon dioxide gas detector is obtained by impregnating a carrier with an ink composition. The ink composition contains a pH indicator, an alkali agent, a water retention agent, a silver-based antimicrobial agent, and water. The content of the silver-based antimicrobial agent in terms of silver is 0.001-0.02 mass% with respect to the total amount of the carbon dioxide gas detector.

Description

Carbon dioxide detector

[0001] The present invention relates to a carbon dioxide gas detector.

[0002] To preserve foods, beverages, and medicines that may deteriorate when exposed to oxygen, inert gases that do not react with the contents are sealed inside packaging. Carbon dioxide is a widely used gas for such purposes. Carbon dioxide is also used to preserve foods, beverages, and medicines that may deteriorate in quality or lose their medicinal properties due to the release of carbon dioxide. However, damage to the packaging can reduce the carbon dioxide concentration inside, leading to deterioration of the contents.

[0003] In particular, bicarbonate-containing medicinal solutions are drugs that lose their efficacy by releasing carbon dioxide gas. Therefore, by packaging a container containing a bicarbonate-containing medicinal solution together with carbon dioxide gas in a gas-barrier packaging container, the release of carbon dioxide gas is prevented during storage. However, if a pinhole or poor seal occurs due to a defect in the packaging material itself, a mistake in sealing the contents, or impact during transportation (e.g., distribution) or handling at home or in a hospital, the atmosphere in the gas-exchange package may change, resulting in deterioration of the contents. Furthermore, there is a risk that the change in the atmosphere in the gas-exchange package may be unaware and the product may be distributed. A simple method to prevent this situation is to simultaneously enclose a carbon dioxide gas detector in the packaging container, and studies are being conducted to more easily and accurately confirm the presence of carbon dioxide gas.

[0004] For example, Patent Document 1 discloses a carbon dioxide gas detector package having a breathable substrate as a detector package that requires no handling during use and is free from the risk of the contents scattering. Patent Document 2 also discloses a carbon dioxide gas detector that changes color even in a low-concentration carbon dioxide atmosphere and allows for visual detection of carbon dioxide generation. The carbon dioxide detector comprises a substrate impregnated with an alkaline aqueous solution containing a pH indicator and a water-retaining agent and adjusted so that the pH indicator exhibits an alkaline color, and the substrate is sealed in a small bag with a specific water vapor permeability. Patent Document 3 also discloses a carbon dioxide gas detector ink composition that allows for easily visible color changes, the carbon dioxide gas detector ink containing a pH indicator, a binder, and a solvent.

[0005] JP 2015-219084 A JP 2008-224579 A International Publication No. 2001 / 044385

[0006] As described above, foods, beverages, and pharmaceuticals are examples of products in which carbon dioxide gas is sealed and preserved. Carbon dioxide gas detectors are also sealed in packaging containers along with these products. Because these products contain moisture, mold and other factors can grow on the carbon dioxide gas detector, reducing visibility and making it difficult to determine the hue change of detectors using pH indicators. Furthermore, using antifungal agents or other additives in the detector to prevent mold can change the pH or be affected by the pH, thereby affecting the color development of the pH indicator in the detector. Therefore, there has been a demand for a carbon dioxide gas detector using a pH indicator that suppresses mold and other factors and does not affect hue change or visibility even when used in products such as foods, beverages, and pharmaceuticals. Therefore, an objective of the present invention is to provide a carbon dioxide gas detector that suppresses mold and other factors, has excellent visibility of hue change, and can accurately detect changes in carbon dioxide concentration.

[0007] As a result of intensive research in light of the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a carbon dioxide gas detector in which a carrier is impregnated with an ink composition containing a pH indicator, an alkaline agent, a water-retaining agent, a specific amount of a silver-based antibacterial agent, and water, and have completed the present invention. The present invention provides the following [1] to

[12] .

[0008] [1] A carbon dioxide gas detector having a carrier impregnated with an ink composition, the ink composition containing a pH indicator, an alkali agent, a water retention agent, a silver-based antibacterial agent, and water, the content of the silver-based antibacterial agent being 0.001 to 0.02 mass% of the total amount of the carbon dioxide gas detector, calculated as silver. [2] The carbon dioxide gas detector according to [1], wherein the silver-based antibacterial agent is a supported silver-based antibacterial agent in which silver ions are supported on an antibacterial agent carrier, the antibacterial agent carrier being at least one selected from the group consisting of silicate-based carriers and phosphate-based carriers. [3] The carbon dioxide gas detector according to [1] or [2], wherein the pH indicator is meta-cresol purple. [4] The carbon dioxide gas detector according to any one of [1] to [3], wherein the water retention agent is at least one selected from the group consisting of polyhydric alcohols, polyalkylene glycols, acrylic polymers, and cellulose. [5] A carbon dioxide gas detector according to any one of [1] to [4] above, wherein the mass ratio of water to the carrier (water / carrier) is 0.7 to 1.0. [6] A carbon dioxide gas detector according to any one of [1] to [5] above, wherein the mass ratio of water to the water retention agent (water / water retention agent) is 1.2 to 1.9. [7] A carbon dioxide gas detector according to any one of [1] to [6] above, further comprising a spreading agent. [8] The carbon dioxide gas detector according to [7] above, wherein the spreading agent is silica. [9] A carbon dioxide gas detector package comprising the carbon dioxide gas detector according to any one of [1] to [8] above, and a packaging material containing the carbon dioxide gas detector.

[10] A method for producing a carbon dioxide gas detector, comprising impregnating a carrier with an ink composition containing a pH indicator, an alkali agent, a water retention agent, a silver-based antibacterial agent, and water, and then mixing the ink composition with a spreading agent.

[11] A carbon dioxide-sealed package, characterized in that the carbon dioxide gas detector according to any one of [1] to [8] above or the carbon dioxide gas detector package according to [9] above is placed inside an exterior packaging in which a gas containing carbon dioxide is sealed.

[12] A method for storing a bicarbonate-containing infusion, comprising placing the carbon dioxide gas detector according to any one of [1] to [8] above or the carbon dioxide gas detector package according to [9] above and a bicarbonate-containing infusion inside an exterior packaging in which a gas containing carbon dioxide is sealed.

[0009] According to the present invention, it is possible to provide a carbon dioxide gas detector that is excellent in visibility of hue change and can accurately detect changes in carbon dioxide gas concentration while suppressing the growth of mold and the like.

[0010] [Carbon dioxide gas detector] The carbon dioxide gas detector of the present invention is a carbon dioxide gas detector in which a carrier is impregnated with an ink composition, wherein the ink composition contains a pH indicator, an alkali agent, a water retention agent, a silver-based antibacterial agent, and water, and the content of the silver-based antibacterial agent is 0.001 to 0.02 mass % in terms of silver relative to the total mass of the carbon dioxide gas detector. In the present invention, when the term "carrier" is used simply, it refers to a carrier impregnated with the ink composition, and a carrier that supports silver ions contained in the silver-based antibacterial agent described below is referred to as an "antibacterial agent carrier."

[0011] <Ink Composition> The ink composition contained in the carbon dioxide gas detector contains a pH indicator, an alkaline agent, a water retention agent, a silver-based antibacterial agent, and water.

[0012] (pH indicator) pH indicators are used to detect carbon dioxide gas. By utilizing the pH change caused by the neutralization reaction of alkali with carbon dioxide gas, carbon dioxide gas can be clearly detected even in low concentration ranges. The pH indicator used in the carbon dioxide gas detector of the present invention is preferably an indicator that changes color in a neutral to alkaline range, more preferably an indicator that changes color in a pH range of 7.0 to 10.0, and even more preferably an indicator that changes color in a pH range of 7.2 to 9.6. Indicators that change color in a clearly different range so that a clear determination can be made are also preferred. Furthermore, indicators with high thermal stability so that they can be used even at high temperatures are preferred.

[0013] Examples of pH indicators that change color in a neutral to alkaline range include phenol red, cresol red, curcumin, cyanine, α-naphtholphthalein, metacresol purple, thymol blue, o-cresolphthalein, and phenolphthalein. These can be used alone or in combination of two or more, but when combining two or more, it is preferable to combine indicators that change color to a similar hue. Among these, metacresol purple is preferred as the pH indicator because it changes color in an alkaline range, changes color from purple to yellow at pH 9.0, has a large color change, and is highly chemically stable.

[0014] The amount of the pH indicator is preferably an amount that clearly colors the ink and allows a visually confirmable color change, and is preferably 0.001 to 0.1 mass %, more preferably 0.005 to 0.05 mass %, in the ink composition, and is preferably 0.0005 to 0.05 mass %, more preferably 0.001 to 0.01 mass %, in the carbon dioxide gas detector.

[0015] (Alkaline Agent) Since carbon dioxide gas is detected using a pH indicator, the ink composition used in the carbon dioxide gas detector of the present invention contains an alkaline agent. The alkaline agent is preferably a compound that is highly soluble in water. Examples of alkaline agents include metal phosphates, metal hydroxides, metal silicates, metal sulfites, and metal carbonates, with metal phosphates and metal hydroxides being preferred, and metal phosphates being more preferred. Metal phosphates and metal hydroxides are preferred because they have particularly high solubility in water. Examples of metal phosphates include phosphates of alkali metals, preferably trisodium phosphate. Examples of metal hydroxides include hydroxides of alkali metals, preferably sodium hydroxide and potassium hydroxide, and more preferably sodium hydroxide.

[0016] The amount of the alkaline agent is preferably adjusted depending on the pH of the aqueous solution, and is preferably 0.02 to 1.0% by mass, more preferably 0.1 to 0.5% by mass, in the ink composition, and is preferably 0.01 to 0.5% by mass, more preferably 0.05 to 0.2% by mass, in the carbon dioxide gas detector.

[0017] (Water retention agent) In order to retain moisture, the ink composition used in the carbon dioxide gas detector of the present invention contains a water retention agent. The type of water retention agent is not particularly limited as long as it has the effect of reducing water activity when added to the carbon dioxide gas detector, but the following agents are preferably used. The water retention agent is preferably at least one selected from the group consisting of polyhydric alcohols, polyalkylene glycols, acrylic polymers, and cellulose, and polyhydric alcohols are more preferred. Examples of polyhydric alcohols include glycerin, ethylene glycol, and propylene glycol, and among these, glycerin is preferred. Examples of polyalkylene glycols include polyethylene glycol. Examples of acrylic polymers include polyacrylates and polyacrylic acid esters.

[0018] The amount of the water retention agent in the ink composition is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, from the viewpoint of quickly detecting the carbon dioxide concentration and effectively reducing water activity, and is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, in the carbon dioxide gas detector.

[0019] (Silver-Based Antibacterial Agent) The ink composition used in the carbon dioxide gas detector of the present invention contains a silver-based antibacterial agent, and the content of the silver-based antibacterial agent is 0.001 to 0.02 mass % of the total mass of the carbon dioxide gas detector, calculated as silver. By incorporating the above amount of silver-based antibacterial agent into the carbon dioxide gas detector of the present invention, the carbon dioxide gas detector can be made to have excellent visibility of hue change and accurately detect changes in carbon dioxide concentration while suppressing the growth of mold and other microorganisms. The silver-based antibacterial agent is preferably a supported silver-based antibacterial agent in which silver ions are supported on an antibacterial carrier. The carrier in the silver-based antibacterial agent is referred to as the "antibacterial carrier." Examples of the antibacterial carrier supporting the silver ions include silicate-based carriers and phosphate-based carriers, and are at least one selected from the group consisting of silicate-based carriers and phosphate-based carriers, with silicate-based carriers being more preferred. Examples of silicate-based carriers include zeolite, magnesium aluminometasilicate, calcium silicate, etc., with zeolite being preferred. Examples of phosphate-based carriers include zirconium phosphate and calcium phosphate, with zirconium phosphate being preferred. Among these, the antibacterial agent carrier supporting the silver ions is preferably at least one selected from the group consisting of zeolite and zirconium phosphate, with zeolite being more preferred from the viewpoint of safety. The content of silver ions in the silver-based antibacterial agent is preferably 1 to 20% by mass, more preferably 1 to 15% by mass, even more preferably 1 to 10% by mass, still more preferably 1 to 5% by mass, and even more preferably 2 to 3% by mass, based on the total amount of the silver-based antibacterial agent.

[0020] The content of the silver-based antibacterial agent in the carbon dioxide gas detector is 0.001 to 0.02 mass% in terms of silver, relative to the total mass of the carbon dioxide gas detector. The content of the silver-based antibacterial agent in the carbon dioxide gas detector is preferably 0.0015 to 0.02 mass%, more preferably 0.0015 to 0.01 mass%, even more preferably 0.0015 to 0.009 mass%, still more preferably 0.002 to 0.006 mass%, even more preferably 0.002 to 0.005 mass%, still more preferably 0.002 to 0.004 mass%, and even more preferably 0.002 to 0.003 mass%. More specifically, the content of the silver-based antibacterial agent in the carbon dioxide gas detector is preferably 0.0010 to 0.020 mass%, relative to the total mass of the carbon dioxide gas detector, relative to the total mass of the carbon dioxide gas detector, relative to the total mass of the carbon dioxide gas detector. The content of the silver-based antibacterial agent in the carbon dioxide gas detector, calculated as silver, is preferably 0.0015 to 0.020 mass%, more preferably 0.0015 to 0.010 mass%, even more preferably 0.0015 to 0.0090 mass%, even more preferably 0.0020 to 0.0060 mass%, even more preferably 0.0020 to 0.0050 mass%, even more preferably 0.0020 to 0.0040 mass%, and even more preferably 0.0020 to 0.0030 mass%, relative to the total mass of the carbon dioxide gas detector. When the content of the silver-based antibacterial agent in the carbon dioxide gas detector is within the above range, the growth of mold and other growths can be effectively suppressed, and a carbon dioxide gas detector with excellent visibility of the hue change can be obtained. Therefore, the resulting carbon dioxide gas detector can accurately detect changes in carbon dioxide gas concentration. Even after long-term storage, the visibility of the hue change can be excellent, allowing accurate detection of changes in carbon dioxide gas concentration. They also tend to offer a good balance between cost and performance.

[0021] The amount of the silver-based antibacterial agent is, in terms of silver, preferably 0.002 to 0.04 mass%, more preferably 0.003 to 0.025 mass%, even more preferably 0.003 to 0.02 mass%, still more preferably 0.003 to 0.018 mass%, even more preferably 0.004 to 0.008 mass%, and still more preferably 0.004 to 0.007 mass%, relative to the total amount of the ink composition.

[0022] The amount of the silver-based antibacterial agent is preferably 0.005 to 2 mass %, more preferably 0.01 to 1 mass %, even more preferably 0.03 to 1 mass %, still more preferably 0.03 to 0.5 mass %, even more preferably 0.05 to 0.3 mass %, and still more preferably 0.05 to 0.2 mass %, relative to the total mass of the carbon dioxide gas detector.

[0023] The amount of the silver-based antibacterial agent is preferably 0.01 to 4 mass%, more preferably 0.02 to 2 mass%, even more preferably 0.05 to 2 mass%, still more preferably 0.05 to 1 mass%, even more preferably 0.1 to 0.5 mass%, and still more preferably 0.1 to 0.3 mass%, based on the total amount of the ink composition.

[0024] When the amount of silver-based antibacterial agent is within the above range, it is possible to efficiently suppress the growth of mold and the like and obtain a carbon dioxide gas detector with excellent visibility of the hue change. Therefore, the obtained carbon dioxide gas detector can accurately detect changes in carbon dioxide gas concentration. In particular, even after long-term storage, the visibility of the hue change is excellent and changes in carbon dioxide gas concentration can be accurately detected. In addition, there is a tendency for the detector to have an excellent balance between cost and performance.

[0025] (Water) From the viewpoint of rapid carbon dioxide concentration detection, the water content in the ink composition is preferably 40 to 75% by mass, more preferably 50 to 65% by mass. Furthermore, the water content in the carbon dioxide gas detector is preferably 30 to 40% by mass, more preferably 30 to 38% by mass, even more preferably 32 to 38% by mass, and even more preferably 32 to 36% by mass. From the viewpoint of rapid carbon dioxide concentration detection, the mass ratio of water to the water retention agent (water / water retention agent) is preferably 1.0 to 2.0, more preferably 1.2 to 1.9. By maintaining the mass ratio of water to the water retention agent within the above range, a carbon dioxide gas detector with no unevenness can be obtained during production. This ensures thorough mixing, resulting in a uniform, particulate carbon dioxide gas detector. Furthermore, from the viewpoint of rapid carbon dioxide concentration detection and improved fluidity, the mass ratio of water to the carrier (water / carrier), described below, is preferably 0.5 to 2.0, more preferably 0.7 to 1.0. By setting the mass ratio of water to the carrier within the above range, color development is improved and the composition can be easily filled into packaging materials.

[0026] <Carrier> The carbon dioxide gas detector of the present invention is obtained by impregnating a carrier with the ink composition, and by impregnating the carrier and forming it into a particulate form, the detector has excellent fluidity. Porous particles are preferred as the carrier, and porous inorganic particles are more preferred. Examples of porous inorganic particles include silica gel, diatomaceous earth, zeolite, and porous silicates, with porous silicates being preferred. Among porous silicates, magnesium aluminometasilicate is preferred because it is also suitable for use in food and pharmaceutical products. Furthermore, the carrier is preferably colorless or white so that the color change is clear. The pH of the carrier is preferably neutral to alkaline. From the viewpoints of fluidity and blendability, the average particle size of the carrier is preferably 1 to 500 μm, more preferably 100 to 300 μm. From the viewpoint of fluidity, the shape of the carrier is preferably spherical or approximately spherical, more preferably spherical.

[0027] The amount of the carrier is preferably 20 to 70% by mass, more preferably 30 to 60% by mass, in the carbon dioxide gas detector element, from the viewpoint of speeding up the detection of carbon dioxide gas concentration and improving fluidity.

[0028] <Spreader> The carbon dioxide gas detector of the present invention preferably contains a spreading agent from the viewpoint of improving fluidity while maintaining the clarity of the hue change. The spreading agent is preferably attached to the outer surface of the carrier impregnated with the ink composition. Examples of spreading agents include silicon dioxide, calcium silicate hydrate, magnesium oxide, calcium hydroxide, and charcoal. The charcoal is preferably activated charcoal. The silicon dioxide is preferably silica. The spreading agent is preferably spherical fine particles, more preferably spherical silica, and even more preferably spherical hydrophobic silica.

[0029] The amount of the spreading agent in the carbon dioxide gas detector is preferably 0.1 to 5% by mass, more preferably 0.2 to 2% by mass, from the viewpoint of improving fluidity.

[0030] [Carbon dioxide gas detector package] The carbon dioxide gas detector package of the present invention comprises the carbon dioxide gas detector and a packaging material containing the carbon dioxide gas detector. The carbon dioxide gas detector is in a highly fluid particulate form and can be used as is depending on the application, but it is preferable to package it and store and use it as a carbon dioxide gas detector package. The carbon dioxide gas detector package can be in the form of a bag or box, with the bag being preferred. The packaging material used for the carbon dioxide gas detector package is preferably a transparent resin film, so that the presence or absence of carbon dioxide can be determined visually from the outside by checking the color change. Preferred packaging materials include biaxially oriented polypropylene (OPP), unoriented polypropylene (CPP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), high-density polyethylene (HDPE), polyethylene terephthalate (PET), polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), oriented polyamide (ONY), etc. These materials may be used alone or in combination of two or more. Preferred laminated packaging materials include a laminate film of biaxially oriented polypropylene (OPP) and low-density polyethylene (LDPE).

[0031] Furthermore, since it is necessary to open a portion of the packaging to expose the packaging to the external atmosphere for detecting the carbon dioxide concentration, it is preferable to provide a ventilation hole in a portion of the packaging. The ventilation hole preferably allows carbon dioxide to pass through while blocking the carbon dioxide detector of the present invention. It is preferable that the ventilation hole be formed by a filamentous material or a fine porous membrane, and more preferably by a filamentous material. Examples of porous membranes include nonwoven fabrics. A portion of the filamentous material is present inside the packaging (the carbon dioxide detector housing portion) and a portion of it extends to the outside of the packaging. When the filamentous material forms the ventilation hole, it provides breathability due to the spaces between the fibers constituting the filamentous material or between the fibers and the material used in the packaging. The filamentous material may be an aggregate of fibrous materials that form a thread, and preferably has a melting point of 80°C or higher so as to withstand the molding of the packaging. Sewing thread is a suitable example of such a filamentous material. Examples of the material of the filament include polyethylene terephthalate, cotton, polyester, vinylon, silk, and nylon, with polyethylene terephthalate, nylon, and vinylon being preferred. The thread size is preferably 1 to 100 count, more preferably 10 to 80 count, and even more preferably 15 to 60 count.

[0032] [Method for manufacturing carbon dioxide gas detector] There are no limitations on the method for manufacturing the carbon dioxide gas detector of the present invention, but it is preferable to manufacture it by impregnating a carrier with an ink composition containing a pH indicator, an alkaline agent, a water retention agent, a supported silver-based antibacterial agent, and water, and it is more preferable to manufacture it by impregnating a carrier with an ink composition containing a pH indicator, an alkaline agent, a water retention agent, a supported silver-based antibacterial agent, and water, and then mixing it with a spreading agent.

[0033] It is preferable to use a mixer to stir the ink composition so that the carrier is uniformly impregnated with the ink composition. It is also preferable to use a mixer to stir the ink composition so that the spreading agent is uniformly attached to the periphery of the carrier. The stirring conditions are preferably set at a speed of 10 to 40 rpm.

[0034] [Carbon dioxide gas-sealed package] The carbon dioxide gas-sealed package of the present invention is characterized in that the carbon dioxide gas sensor or the carbon dioxide gas sensor package is placed inside an outer packaging in which a gas containing carbon dioxide gas is sealed. That is, the carbon dioxide gas-sealed package of the present invention is characterized in that the carbon dioxide gas sensor or the carbon dioxide gas sensor package is placed inside an outer packaging in which a gas containing carbon dioxide gas is sealed, the carbon dioxide gas sensor comprising a carrier impregnated with an ink composition containing a pH indicator, an alkaline agent, a water retention agent, a silver-based antibacterial agent, and water, and the content of the silver-based antibacterial agent is 0.001 to 0.02 mass % in terms of silver relative to the total mass of the carbon dioxide gas sensor.

[0035] The carbon dioxide gas-sealed package of the present invention contains a gas containing carbon dioxide gas and the carbon dioxide gas detector inside the package, i.e., inside the exterior packaging, and also contains other contents such as a medicinal liquid, food, etc. The contents such as a medicinal liquid, food, etc. are preferably further contained in a container, and the container is preferably disposed inside the exterior packaging.

[0036] The exterior packaging used in the carbon dioxide gas-sealed package of the present invention is preferably made of a gas barrier material that is difficult for gases including carbon dioxide to pass through. Specific examples include resin films such as ethylene-vinyl alcohol copolymer, polyethylene terephthalate, and nylon, and composite films in which silica, alumina, or the like is vapor-deposited onto these resin films. However, part or all of the exterior packaging is transparent so that the color change of the carbon dioxide gas detector can be visually recognized from the outside of the exterior packaging. The carbon dioxide-containing gas may be composed of carbon dioxide gas alone, or may be composed of carbon dioxide gas and an inert gas such as nitrogen gas. The carbon dioxide concentration in the carbon dioxide-containing gas is preferably 1 to 50%, more preferably 1 to 15%, and even more preferably 3 to 10%.

[0037] The contents to be placed in the carbon dioxide gas-sealed package of the present invention include medicinal liquids, foods, etc., and specifically include medicinal liquids containing bicarbonate such as sodium bicarbonate, fruits and vegetables, raw meat, and confectioneries. In particular, when bicarbonate-containing infusion liquids are used as medicinal liquids, the carbon dioxide gas detector can detect the carbon dioxide gas concentration in a short time, allowing for early use or transfer and storage in a carbon dioxide gas atmosphere, thereby suppressing product deterioration, which is preferable.

[0038] [Method for Preserving Bicarbonate-Containing Infusions] The method for preserving bicarbonate-containing infusions of the present invention involves placing the carbon dioxide detector or the carbon dioxide detector package and the bicarbonate-containing infusion in an exterior package containing a gas containing carbon dioxide. Specifically, the method for preserving bicarbonate-containing infusions of the present invention involves impregnating a carrier with an ink composition containing a pH indicator, an alkaline agent, a water-retaining agent, a supported silver-based antibacterial agent, and water, and placing the carbon dioxide detector or the carbon dioxide detector package, in which the supported silver-based antibacterial agent content is 0.001 to 0.02 mass% in terms of silver relative to the total weight of the carbon dioxide detector, and the bicarbonate-containing infusion in an exterior package containing a gas containing carbon dioxide. Bicarbonate-containing infusions (bicarbonate-containing infusions) are used as extracellular fluid replacement fluids, and bicarbonate ions are used as an alkalizing agent to correct extracellular fluid. Bicarbonate-containing infusions (bicarbonate-containing infusions) have the property of losing their medicinal efficacy upon release of carbon dioxide. For this reason, a container containing bicarbonate-containing infusion (bicarbonate-containing infusion) is packaged together with carbon dioxide gas in a gas-barrier packaging container, thereby preserving the infusion while preventing the release of carbon dioxide gas.

[0039] When storing bicarbonate-containing infusion in a gas containing carbon dioxide, the use of the carbon dioxide detector allows a decrease in the carbon dioxide concentration in the gas to be detected in a short period of time, making it possible to use up the bicarbonate-containing infusion, which is prone to deterioration, early or to store it again in a carbon dioxide atmosphere, which is preferable because it allows the deterioration of the bicarbonate-containing infusion to be efficiently prevented.

[0040] The outer packaging used in the preservation method of the present invention is preferably an outer packaging that can be suitably used for the carbon dioxide gas-sealed package. Specifically, it is preferably made of a gas barrier material that is difficult for gases including carbon dioxide to pass through, and specific examples include resin films such as ethylene-vinyl alcohol copolymer, polyethylene terephthalate, and nylon, and composite films in which silica, alumina, etc. are vapor-deposited onto these resin films. The carbon dioxide gas is preferably made of carbon dioxide gas and nitrogen gas. The carbon dioxide gas concentration in the carbon dioxide gas is preferably 1 to 50%, more preferably 1 to 15%, and even more preferably 3 to 10%.

[0041] The temperature during storage in the storage method of the present invention is preferably 5 to 40°C.

[0042] The preservation method of the present invention is particularly effective when transferring or transporting bicarbonate-containing infusions. That is, a preferred method for transferring or transporting bicarbonate-containing infusions involves placing the carbon dioxide detector and the bicarbonate-containing infusion in an exterior package containing a gas containing carbon dioxide. When transferring or transporting bicarbonate-containing infusions, external stimuli or impacts often cause damage to the exterior package that cannot be detected visually. However, the carbon dioxide detector can detect a decrease in carbon dioxide concentration in a short period of time even after storage, allowing bicarbonate-containing infusions whose exterior package has been damaged to be used up quickly or to be stored again in a carbon dioxide atmosphere, which is preferred because it efficiently prevents deterioration of the bicarbonate-containing infusion.

[0043] EXAMPLES The present invention will be explained in more detail below using examples and comparative examples, but the present invention is not limited to these examples.

[0044] [Evaluation] The carbon dioxide gas detectors obtained in the Examples and Comparative Examples were evaluated as follows. <Antibacterial Properties and Appearance of Carbon Dioxide Gas Detectors After Storage> (Preparation of Carbon Dioxide Gas Detector Package) 0.2 g of the carbon dioxide gas detectors obtained in the Examples and Comparative Examples were placed in a 2.5 cm x 3.0 cm bag (with breathable thread) made of transparent laminated film of OPP / LLDPE, and the opening was heat-sealed to seal, thereby obtaining a packaged carbon dioxide gas detector. (Test Method) [1] Evaluation of Antibacterial Properties 0.2 g of the carbon dioxide gas detectors obtained in the Examples and Comparative Examples were infected with Cladosporium bacteria and stored at 25°C for one month. The stored carbon dioxide gas detectors were then inoculated into PDA medium. The inoculated PDA medium was cultured at 25°C for five days, after which the colonies were counted. The fewer the colony counts, the better the antibacterial properties. The following evaluation was performed based on the colony count, with A being considered a pass. In the carbon dioxide gas detector with excellent antibacterial properties, mold is not visible even after storage, the appearance after storage is excellent, and the visibility of the color change accompanying the change in carbon dioxide concentration is excellent. Note that although the number of colonies was not counted in Example 1, since mold did not appear on the appearance of the carbon dioxide gas detector after storage, it was rated as A based on the following evaluation criteria. (Evaluation criteria) A: Number of colonies less than 500 B: Number of colonies 500 or more but less than 1500 C: Number of colonies 1500 or more

[0045] [2] Evaluation of the appearance of the carbon dioxide gas detector after storage (Manufacturing of carbon dioxide gas detector package) 0.2 g of the carbon dioxide gas detector obtained in the examples and comparative examples was placed in a 2.5 cm x 3.0 cm bag made of transparent OPP / LLDPE film (with breathable thread), and the opening was heat-sealed to obtain a carbon dioxide gas detector package.

[0046] (Storage and Evaluation of Carbon Dioxide Gas Detector Package) The carbon dioxide gas detector package was placed in a 250 mL bag made of gas barrier film, the opening was heat-sealed, and the carbon dioxide gas detector was stored. The appearance of the carbon dioxide gas detector was observed after 2 weeks and 6 weeks. The appearance of the carbon dioxide gas detector after 2 weeks and 6 weeks was compared with the appearance of the carbon dioxide gas detector immediately after storage, and the time when black aggregates appeared and the proportion of black aggregates after 6 weeks were evaluated. The proportion of black aggregates after 6 weeks was evaluated according to the following criteria. In Table 1, samples that did not show any black aggregates even after 6 weeks were marked "no aggregates." The slower the black aggregates appeared and the lower the proportion of black aggregates, the better the appearance after storage. Furthermore, samples that did not show any black aggregates had better appearance after storage and were extremely good at visualizing the hue change associated with changes in carbon dioxide concentration. Furthermore, the carbon dioxide gas detector of the example did not show any change in hue of the detector itself before and after 6 weeks of storage, indicating that the use of a silver-based antibacterial agent had no effect on the color development of the carbon dioxide gas detector. This demonstrates that accurate detection is possible with the carbon dioxide gas detector of the present invention. (Evaluation criteria) A: No black aggregates observed (0%) B: The proportion of black aggregates is greater than 0% and less than 30% C: The proportion of black aggregates is 30% or more and less than 50% D: The proportion of black aggregates is 50% or more and less than 70% E: The proportion of black aggregates is 70% or more and less than 90% F: The proportion of black aggregates is 90% or more

[0047] Carbon Dioxide Gas Detector Example 1: 83 g of distilled water was mixed with 0.016 g of meta-cresol purple (pH indicator), 0.25 g of trisodium phosphate dodecahydrate (alkali agent), 59.5 g of glycerin (humectant), and 0.12 g of Zeomic (antibacterial agent carrier: zeolite, silver content: 2.5% by mass, manufactured by Sinanen Zeomic Co., Ltd.) to obtain a purple ink composition. This ink composition was impregnated into 100 g of magnesium aluminometasilicate carrier (product name: Neusilin SG2, average particle size: approximately 200 μm), and 0.75 g of hydrophobic silica (spreader) was added and stirred to obtain a purple carbon dioxide gas detector. The evaluation results are shown in Table 1.

[0048] Examples 2 to 6 and Comparative Examples 1 to 5 Purple carbon dioxide gas detectors were obtained in the same manner as in Example 1, except that the type and amount of the silver-based antibacterial agent were changed as shown in Table 1. The evaluation results are shown in Table 1.

[0049] Comparative Example 6 A purple carbon dioxide gas detector was obtained in the same manner as in Example 1, except that no silver-based antibacterial agent was used. The evaluation results are shown in Table 1.

[0050]

[0051] As shown in Table 1, the carbon dioxide gas detector of the present invention inhibits the growth of black mold even after storage and no aggregates are observed, demonstrating excellent visibility of the hue change even after storage. Therefore, it is clear that the carbon dioxide gas detector of the present invention inhibits the growth of mold and other growths while providing excellent visibility of the hue change and enabling accurate detection of changes in carbon dioxide concentration.

Claims

1. A carbon dioxide gas detector having a carrier impregnated with an ink composition, said ink composition containing a pH indicator, an alkaline agent, a water retention agent, a silver-based antibacterial agent and water, and the content of said silver-based antibacterial agent is 0.001 to 0.02 mass % in terms of silver relative to the total mass of the carbon dioxide gas detector.

2. A carbon dioxide gas detector as described in claim 1, wherein the silver-based antibacterial agent is a supported silver-based antibacterial agent in which silver ions are supported on an antibacterial agent carrier, and the antibacterial agent carrier is at least one selected from the group consisting of silicate-based carriers and phosphate-based carriers.

3. A carbon dioxide gas detector as described in claim 1 or 2, wherein the pH indicator is meta-cresol purple.

4. A carbon dioxide gas detector according to any one of claims 1 to 3, wherein the water retention agent is at least one selected from the group consisting of polyhydric alcohols, polyalkylene glycols, acrylic polymers and cellulose.

5. A carbon dioxide gas detector according to any one of claims 1 to 4, wherein the mass ratio of water to the carrier (water / carrier) is 0.7 to 1.

0.

6. A carbon dioxide gas detector according to any one of claims 1 to 5, wherein the mass ratio of water to the water retention agent (water / water retention agent) is 1.2 to 1.

9.

7. The carbon dioxide gas detector according to any one of claims 1 to 6, further comprising a spreading agent.

8. The carbon dioxide gas detector according to claim 7, wherein the spreading agent is silica.

9. A carbon dioxide gas detector package comprising the carbon dioxide gas detector according to any one of claims 1 to 8 and a packaging material containing the carbon dioxide gas detector.

10. A method for manufacturing a carbon dioxide gas detector, comprising impregnating a carrier with an ink composition containing a pH indicator, an alkaline agent, a water retention agent, a silver-based antibacterial agent and water, and then mixing it with a spreading agent.

11. A carbon dioxide gas-sealed package comprising a carbon dioxide gas detector according to any one of claims 1 to 8 or a carbon dioxide gas detector package according to claim 9, disposed within an exterior body containing a gas containing carbon dioxide gas.

12. A method for storing a bicarbonate-containing infusion, comprising placing the carbon dioxide gas detector according to any one of claims 1 to 8 or the carbon dioxide gas detector package according to claim 9 and a bicarbonate-containing infusion in an exterior packaging in which gas containing carbon dioxide is sealed.

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