TW201840966A - Oxygen detecting agent and method for producing oxygen detecting agent capable of ensuring obvious color tone change and good color change reactivity - Google Patents

Abstract

The object of the present invention is to provide an oxygen detecting agent which ensures obvious color tone change and good color change reactivity and is excellent in surface adhesion even on a hydrophobic substrate, and a method for producing the oxygen detecting agent. In order to achieve such purpose, the present invention provides an oxygen detecting agent having a substrate on which an adhesive layer containing magnesium hydroxide and adhesive, and an oxygen detecting layer containing a redox pigmet that changes color tone depending on the presence or absence of oxygen in the ambient gas are sequentially laminated from the substrate side. In addition, when the oxygen detecting agent is manufactured, the adhesive layer and the oxygen detecting layer are sequentially laminated on the substrate.

Description

 Oxygen detecting agent and method for producing oxygen detecting agent  

The present invention relates to a method for producing an oxygen detecting agent and an oxygen detecting agent which can visually recognize a change in the amount of oxygen in an ambient gas by a change in color tone, and more particularly relates to an oxygen detecting agent having a laminated structure and A method of producing the oxygen detecting agent.

When preserving foods, pharmaceuticals, etc., oxygen in the environmental gas oxidizes foods, pharmaceuticals, etc., and the quality of foods, pharmaceuticals, etc. falls. Therefore, in order to prevent deterioration in quality during storage, foods, pharmaceuticals, and the like are placed in a container package together with a deoxidizer, and the oxygen in the container package is absorbed by a deoxidizer or the like to deoxidize (referred to as oxygen). Foods, pharmaceuticals, etc. are stored in a state where the concentration is 0.1% or less.

In recent years, an oxygen detecting agent is enclosed in a container package together with a deoxidizing agent, and the presence or absence of oxygen in the container package is detected by an oxygen detecting agent. The oxygen detecting agent can visually recognize the presence or absence of oxygen in the sealed container package by the change in color tone. The user can easily confirm whether the food or the medicine is stored in a deoxidized state based on the color tone exhibited by the oxygen detecting agent.

Such an oxygen detecting agent is usually composed of a reducing agent, a basic substance, and a redox dye having a color difference in an oxidized state and a reduced state. The reducing agent is used to maintain the redox dye in a reduced state when the ambient gas is in a deoxidized state. In this manner, the oxygen detecting agent detects the oxygen by utilizing a design in which the redox dye maintained in the reduced state is oxidized by the oxygen in the ambient gas to change the color tone. Therefore, it is required for the oxygen detecting agent system to have a clear color tone change and a good color change reactivity as the amount of oxygen in the ambient gas changes.

In the past, as such an oxygen detecting agent, a tablet type oxygen detecting agent formed into a tablet form or a sheet type oxygen detecting agent in which an oxygen detecting composition solution is impregnated on a sheet-shaped carrier such as paper can be used. As a result, in the past, the oxygen detecting agent has to package the tablet-shaped or sheet-shaped oxygen detecting agent individually, so that the manufacturing process of the oxygen detecting agent is complicated. Further, when an oxygen detecting agent is used, it is necessary to enclose the deoxidizing agent together with the oxygen detecting agent into the container package, which takes time and labor. Therefore, there has been proposed a product in which a deoxidizing agent and an oxygen detecting agent are integrated by attaching an oxygen detecting agent or the like which is individually packaged to the surface of a packaging material of a deoxidizing agent. However, in this case, there is a problem that the manufacturing steps of the product are very complicated.

On the other hand, in recent years, there has been proposed a so-called printing type oxygen detecting agent (for example, see Japanese Patent Application Laid-Open No. Hei. No. Hei. The printed oxygen detecting agent can be realized, for example, by coating or printing an oxygen detecting composition on a container packaging material such as food or medicine, so that in addition to the individual packaging which does not require an oxygen detecting agent, the container can be omitted. The step of enclosing the oxygen detecting agent in the package. Further, since it can be realized by coating or printing an oxygen detecting agent composition on a packaging material of a deoxidizing agent, the manufacturing steps of the product in which the deoxidizing agent and the oxygen detecting agent are integrated can be greatly simplified.

Here, the change in color tone accompanying the redox reaction of the redox dye is carried out in a system using water as a medium. Therefore, the oxygen detecting agent composition contains moisture. The oxygen detecting agent described in Japanese Laid-Open Patent Publication No. 2016-75546 uses a paper substrate, so that the oxygen detecting agent composition is impregnated into the substrate. However, when a substrate having no water absorbability such as a plastic film is used, the moisture content in the oxygen detecting agent composition increases, and it becomes difficult to apply or print the oxygen detecting agent composition on the surface of the substrate, and it becomes difficult to manufacture. A printed oxygen detecting agent having good adhesion to a substrate.

An object of the present invention is to provide an oxygen detecting agent and a method for producing the oxygen detecting agent which are excellent in surface color adhesion of a hydrophobic substrate, which ensures a remarkable color tone change and good color change reactivity.

In order to solve the above problems, the oxygen detecting agent of the present invention is applied to a substrate to form an adhesive layer containing magnesium hydroxide and an adhesive, and an oxygen detecting agent containing a redox dye which changes color tone depending on the presence or absence of oxygen in the ambient gas. The layer is laminated in this order from the substrate side.

In the oxygen detecting agent of the present invention, the oxygen detecting layer has a basic substance layer containing a basic substance, and a redox pigment layer containing a reducing agent and the redox dye, and the substrate is formed on the adhesive layer. The two-layer structure in which the side layers are laminated in this order is preferable.

In the oxygen detecting agent according to the invention of the present invention, the substrate is preferably a transparent resin substrate.

In the oxygen detecting agent according to the invention of the present invention, the above-mentioned adhesive is preferably polyvinyl alcohol.

In the oxygen detecting agent according to the invention of the present invention, the alkaline substance is preferably sodium carbonate.

In the oxygen detecting agent according to the invention of the present invention, the reducing agent is preferably a reducing sugar.

In order to solve the problem, the method for producing an oxygen detecting agent according to the present invention is a method for producing an oxygen detecting agent capable of detecting the presence or absence of oxygen in an ambient gas by a change in color tone of a redox dye, and comprises: forming a substrate on a substrate a step of adhering a layer of magnesium hydroxide and an adhesive; and forming an oxygen detecting layer containing a redox dye having a change in color tone depending on the presence or absence of oxygen in the ambient gas on the adhesive layer.

According to the invention of the present invention, it is possible to provide an oxygen detecting agent and a method for producing the oxygen detecting agent which ensure excellent color tone change and good color change reactivity even in the surface of the hydrophobic substrate.

1‧‧‧Substrate

2‧‧‧Adhesive layer

3‧‧‧Alkaline material layer

4‧‧‧redox pigment layer

Fig. 1 is a schematic view showing the layer constitution of an oxygen detecting agent according to an embodiment of the present invention.

Fig. 2 is a schematic view showing the layer constitution of an oxygen detecting agent of another embodiment of the present invention.

Fig. 3 is a view showing a change in reflectance spectrum of the oxygen detecting agent of Example 1 from a deoxidized state to an aerobic state with time.

Fig. 4 is a view showing a change in the reflectance spectrum of the oxygen detecting agent of Comparative Example 1 from the deoxidized state to the aerobic state with time.

Fig. 5 is a view showing a change in the reflectance spectrum of the oxygen detecting agent of Comparative Example 2 from the deoxidized state to the aerobic state with time.

Fig. 6 is a view showing a change in coloration when the oxygen detecting agent of Example 1 was repeatedly used.

Hereinafter, preferred embodiments of the oxygen detecting agent and the method for producing an oxygen detecting agent of the present invention will be described.

 【Symbol Description】  

Oxygen detector

The layer configuration of the oxygen detecting agent of the present embodiment is shown in Fig. 1. As shown in Fig. 1, the oxygen detecting agent of the present embodiment has an adhesive layer 2 containing magnesium hydroxide and an adhesive, a basic substance layer 3 containing a basic substance, and a reducing agent and oxidation on the substrate 1. The redox pigment layer 4 of the reducing dye is laminated in this order from the side of the substrate 1 described above. The oxygen detecting agent can visually recognize the change in the amount of oxygen in the environmental gas in the container package containing the food or the pharmaceutical product (hereinafter referred to as "the oxygen detecting environment") by the change in the color tone of the redox dye. By. In the oxygen detecting agent of the present embodiment, the oxygen detecting function is exhibited by the two layers of the basic substance layer 3 and the redox pigment layer 4. However, the oxygen detecting agent of the present invention is provided with a redox dye containing a change in color tone depending on the presence or absence of oxygen in the ambient gas, or by maintaining the reducing dye on the substrate 1 via the adhesive layer 2. The oxygen detecting layer composed of the oxygen detecting composition such as the reducing agent in the state may be used, and the components constituting the oxygen detecting composition of the present embodiment may be partitioned into a plurality of layers, or the oxygen detecting composition may be formed. All the components are disposed on one layer, and the specific configuration thereof is not particularly limited. Hereinafter, each layer will be described. Further, in the following, two layers of the basic substance layer 3 and the redox pigment layer 4 are referred to as an oxygen detecting layer.

(1) Substrate 1

In the present invention, the substrate 1 is not particularly limited. For example, a paper base material 1, a resin base material 1 and the like can be used, and the shape thereof is not particularly limited. In particular, a paper container packaging material or a resin container packaging material formed into various shapes such as a film shape, a packaging bag shape, and a packaging container shape is preferable as the substrate 1 . The oxygen detecting agent of the present invention can be formed on the surface of the substrate 1, for example, by coating or printing an ink-like composition for forming the oxygen detecting layer. Therefore, since the container packaging material is used as the substrate 1, the container packaging material with the oxygen detecting function can be easily obtained by a printing method or the like.

Further, in the oxygen detecting agent of the present invention, the substrate 1 is more preferably a transparent resin substrate 1. Since the oxygen detecting layer is provided on the transparent resin substrate 1 via the adhesive layer 2, the change in color tone of the redox dye can be visually recognized from the side of the transparent resin substrate 1. Therefore, when the oxygen detecting agent is used, the substrate 1 side can prevent the oxygen detecting composition such as foods and pharmaceuticals in the oxygen detecting environment from being subjected to an oxygen detecting composition such as a redox dye. The constituents are in contact.

As the transparent resin substrate 1, for example, a resin substrate 1 composed of polyester, polyethylene, polypropylene, polyamide or the like can be used. The presence or absence of oxygen in the oxygen detecting environment is detected via the substrate 1, and the substrate 1 must have oxygen permeability. Therefore, when a transparent resin substrate 1 composed of a polyester having a small amount of oxygen permeation, polyamide or the like is used, an extremely small hole having a degree of ensuring gas permeability and having both water repellency and oil repellency is used. The porous transparent resin substrate 1 is preferred. In such a transparent resin substrate 1, more specifically, polyethylene terephthalate (PET) can be used as the polyester, and low density polyethylene (LDPE), linear low density polyethylene can be used as the polyethylene. (LLDPE), as the polypropylene, unstretched polypropylene (CPP), biaxially oriented polypropylene (OPP), or the like can be used. These synthetic resin films are used not only as a single layer film but also as a laminated film in which a film of a different material is laminated.

In the oxygen detecting agent of the present invention, even when a hydrophobic substrate 1 such as polyester is used, oxygen composed of two layers of the basic substance layer 3 and the redox pigment layer 4 can be passed through the adhesive layer 2 described below. The detection layer is adhered to the substrate 1 with good adhesion. Further, in the present embodiment, the oxygen detecting agent of the present invention will be described mainly by taking the case of using the transparent resin substrate 1. However, as described above, the substrate 1 of the present invention is not particularly limited, and is not limited to the transparent resin substrate 1, and the opaque resin substrate 1 may be used, or the paper substrate 1 may be used. Further, the surface of the substrate 1 on the side where the oxygen detecting layer is provided may be subjected to a hydrophilic treatment.

(2) Adhesive layer 2

Next, the adhesive layer 2 will be described. The adhesive layer 2 is a layer containing magnesium hydroxide and an adhesive. The adhesive layer 2 is formed of a mixture of magnesium hydroxide fine particles and an adhesive so that the magnesium hydroxide fine particles are dispersed in the adhesive. Since the particulate magnesium hydroxide is dispersed in the adhesive, the adhesive layer 2 appears white. By providing a white layer on the substrate 1, the change in color tone of the redox pigment can be clearly visually recognized.

The adhesive is a component for adhering the substrate 1 to each component constituting the oxygen detecting layer. As described below, the oxygen detecting agent of the present invention can be produced by coating or printing a water-based ink composition dissolved or dispersed therein in an aqueous solvent containing constituent components of the respective layers on the substrate 1. When the substrate 1 is a hydrophobic transparent resin substrate 1, when the direct aqueous ink-like composition is applied or printed on the substrate 1, the wetness of the aqueous ink-like composition to the substrate 1 is obtained. Poor, it is difficult to coat or print the aqueous ink composition on the substrate 1 in a uniform thickness. However, according to the present invention, by providing the adhesive layer 2 on the substrate 1, the wettability of the aqueous ink-like composition on the surface of the substrate 1 can be improved.

Therefore, it becomes possible to apply or print the aqueous ink-like composition favorably on the surface of the adhesive layer 2 with a uniform thickness, and to provide the alkaline substance layer 3 excellent in adhesion and oxidation on the substrate 1 via the adhesive layer 2. Reducing pigment layer 4. Therefore, the redox pigment can be uniformly distributed over the entire area of the color developing region on the substrate 1, and a uniform and uniform color development without color spots can be achieved.

Here, it is preferred to use a water-soluble resin as the adhesive. The water-soluble resin may be, for example, various modified resins in which a hydrophilic group such as a hydroxyl group is introduced, in addition to polyvinyl alcohol (PVA), an acrylic resin, or the like. Water can be used as a solvent when the adhesive layer 2 is formed by using a water-soluble resin as an adhesive. In the step of producing the oxygen detecting agent, if there is a step of using an organic solvent, there is a fear that the remaining organic solvent will volatilize in the storage container and adhere to the food or the pharmaceutical. If a water-soluble resin is used as the adhesive, since it is not necessary to use an organic solvent, the above-mentioned concerns are not preferable.

Further, the change in color tone accompanying the redox reaction of the redox dye is carried out in a system using water as a medium. By providing the adhesive layer 2 containing a water-soluble resin as an adhesive, it is possible to easily maintain the water necessary for the redox reaction of the redox dye on the substrate 1. Therefore, unlike the conventional one, an oxygen detecting agent having excellent discoloration reactivity can be realized on the hydrophobic substrate 1 without using a support such as the water-containing substrate 1 or the porous ceria. In particular, since polyvinyl alcohol has a high proportion of hydroxyl groups contained in the molecular structure, if polyvinyl alcohol is used as an adhesive, it is easy to maintain the necessary moisture in the above-described redox reaction in the adhesive layer 2, and it is possible to obtain a rapid A color-reactive oxygen detecting agent.

On the other hand, when a water-soluble resin is used as an adhesive, when the aqueous ink-like composition is applied or printed on the adhesive layer 2, the water-soluble resin in the adhesive layer 2 may be dissolved in the aqueous ink-like composition. In the water. However, in the present invention, by dispersing magnesium hydroxide in the adhesive layer 2, the redox reaction of the redox dye can be favorably performed as compared with the case where magnesium hydroxide is not contained, and a good color change reaction can be obtained. Sex, therefore, it is speculated that the water retention of the adhesive layer can be improved. Further, when the aqueous ink composition is applied or printed on the surface of the adhesive layer 2, the effect of preventing the water-soluble resin constituting the adhesive layer 2 from being dissolved in the water contained in the aqueous ink composition can be expected.

Further, from the viewpoint of improving the water retention property of the adhesive layer 2, for example, a composition containing glycerin may be used. The more the glycerin content, the more difficult it is to cure the adhesive layer. Therefore, the glycerin content must be appropriately adjusted so as not to hinder the curing of the adhesive layer.

(3) alkaline substance layer 3

In the oxygen detecting agent of the present embodiment, a reducing saccharide is used as a reducing agent for maintaining a redox dye in a reduced state in an oxygen-free environment. The reducing sugar is opened in an aqueous solution, and the aldehyde having a reducing group becomes a ring-opening body. However, this open-loop body does not function as a reducing agent for a redox dye in a neutral aqueous solution, but acts as a reducing agent with respect to a redox pigment system in the case of alkaline conditions. Therefore, in the case where the redox dye is reduced by the reducing saccharide, a basic substance (alkaline agent) is necessary. Therefore, the oxygen detecting agent of the present embodiment is provided on the substrate 1 with the alkaline substance layer 3 containing a basic substance.

As the alkaline substance, for example, an alkali metal salt can be used, and in particular, a carbonate of an alkali metal such as sodium carbonate or potassium carbonate is preferably used. Although an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide can be used, since these are strong bases, browning reaction of reducing sugars is apt to occur. Therefore, it is preferred to use a carbonate which is an alkali metal of a weak base. Further, in the oxygen detecting agent of the present embodiment, the oxygen detecting layer has a two-layer structure of the basic substance layer 3 and the redox dye layer 4, and the redox pigment layer 4 contains a reducing dye. The browning reaction of the reducing pigment can be made less likely to occur.

(4) Redox pigment layer 4

In the oxygen detecting agent of the present embodiment, the redox pigment layer 4 contains a reducing agent and a redox dye.

The redox dye is a dye which is reduced by a reducing agent and which is a dye which reversibly changes color in an oxidized state and a reduced state. Examples of such a coloring matter include methylene blue, neomethylene blue, phenol red, Lauth's violet, and methylene green. For example, when methylene blue is used, when the oxygen detection environment is in a deoxidized state, it becomes a reduced structure (colorless methylene blue) and is colorless. On the other hand, when the oxygen detection environment is in an aerobic state, methylene blue is an oxidized structure and is blue.

As the reducing agent, a reducing sugar can be used. Specifically, monosaccharides such as D-mannose, D-glucose, D-fructose, D-erythritol, and D-aldose; reducing disaccharides such as maltose and lactose; maltotriose, Reducing trisaccharides such as cellulose trisaccharide, mannotriose and pannoose. Among these, in particular, from the viewpoint of high reactivity and high reductive power of the redox pigment, it is preferred to use a monosaccharide as compared with the reducing disaccharide and the reducing trisaccharide. Further, among monosaccharides, D-glucose is particularly preferred. Further, products having a high purity of D-glucose (for example, a purity of 99% or more) are easy to be put on the market at a low price. Further, as the reducing agent, ascorbic acid or the like may be used in addition to the reducing sugar.

Further, the oxygen detecting agent of the present embodiment is intended to provide, for example, only the adhesive layer 2, the basic substance layer 3, and the redox pigment layer 4 in a color developing region of a specific shape such as a character or a mark on the substrate 1. The color tone of the color-developing region of a specific shape is changed depending on the presence or absence of oxygen, thereby making it possible to visually recognize the presence or absence of oxygen. For example, when a coloring matter which is colorless in a reduced state, such as methylene blue or phenol red, is used, it can be displayed by a character or a symbol only when oxygen is present in the oxygen detecting environment.

However, the oxygen detecting agent of the present invention, such as a conventional type of oxygen detecting agent formed into a tablet form or a sheet form, may also add a dye which is not reduced by the reducing agent to the oxygen detecting layer, and may be subjected to an oxygen detecting environment. The presence or absence of oxygen, and the appearance of different colors. For example, when methylene blue is used as the redox dye, it is conceivable to add edible red pigment to the oxygen detecting layer. At this time, when the oxygen detecting environment is in the deoxidized state, the oxygen detecting layer is red due to consumption of red pigment, and when the oxygen detecting environment is in an aerobic state, the oxygen detecting layer is blue to blue-violet. In this way, the color change can also be made depending on the presence or absence of oxygen in the oxygen detecting environment.

(5) Second substrate 5

In the other aspect, the oxygen detecting agent of the present embodiment described above may be used by adhering the redox dye layer 4 to the second base material 5 as shown in FIG. The second substrate 5 can be the same as the substrate 1 described above. As the second base material 5, for example, a packaging material of a deoxidizing agent, a packaging material of a food or a pharmaceutical, or the like can be used.

In this case, an adhesive layer is provided on the surface of the redox pigment layer 4, and the oxygen detecting agent is processed into a sealed shape, and the oxygen detecting agent cut into a specific size can be easily attached to the packaging material, food, or medicine of the deoxidizing agent. Packaging materials such as products. When such an oxygen detecting agent processed into a sealed shape is used, a product in which a deoxidizing agent and an oxygen detecting agent are integrated can be easily manufactured. Further, when the oxygen detecting agent is attached to a packaging material such as a food or a pharmaceutical product, the time and labor for sealing the oxygen detecting agent into the packaging container can be omitted when packaging the food or the pharmaceutical product.

2. Method for producing oxygen detecting agent

Next, an embodiment of a method for producing an oxygen detecting agent of the present invention will be described. The method for producing an oxygen detecting agent according to the present invention is a method for producing an oxygen detecting agent capable of detecting the presence or absence of oxygen in an ambient gas by a change in color tone of a redox dye, comprising: forming magnesium hydroxide on the substrate 1 And a step of adhering the adhesive layer 2 to the adhesive; and forming, on the adhesive layer 2, a step of forming an oxygen detecting layer of a redox dye having a change in color tone depending on the presence or absence of oxygen in the ambient gas.

The adhesive layer 2 and the oxygen detecting layer are as described above, and the two-layer structure in which the oxygen detecting layer is the basic substance layer 3 and the redox pigment layer 4 in the present embodiment is also as described above.

Hereinafter, a method of forming each layer will be specifically described.

(1) Adhesive layer 2

First, the adhesive layer 2 is formed into a solution on the substrate 1 so as to have a specific thickness, and is applied by a bar coater or the like and dried. The formation of the adhesive layer 2 can be prepared by dissolving the adhesive in a solvent and dispersing the magnesium hydroxide in the solvent. The mixing ratio of the adhesive to the magnesium hydroxide (mass mixing ratio) is preferably 100 to 2,000, preferably 400 to 1,500, more preferably 600 to 1200, when the adhesive amount (solid content) is 100. . As the adhesive, as described above, the water-soluble resin is particularly preferably polyvinyl alcohol. At this time, it is preferred to use water as a solvent. Further, the viscosity of the solution forming the adhesive layer 2 is preferably adjusted in view of the workability at the time of coating on the substrate 1.

However, since the preferable range of the mixing ratio of the above-mentioned adhesive and magnesium hydroxide varies depending on the degree of polymerization of the resin used as the adhesive, etc., it is not limited to the above-described mixing ratio, and can be appropriately adjusted.

After the adhesive layer 2 forming solution is applied onto the substrate 1, a certain amount of moisture can be maintained even if it is dried. For example, when polyvinyl alcohol is used as the adhesive, it is presumed that the quality of the polyvinyl alcohol is about 5% to 15% by mass. Further, as described above, from the viewpoint of improving the water retention property of the adhesive layer 2, it may be a composition containing glycerin. However, when the content of glycerin in the solution of the adhesive layer 2 is larger, the adhesive layer 2 is not cured even after it is applied by the solution layer 2, even if it is dried. Therefore, when glycerin is added, it is preferably 5% by mass or less based on the polyvinyl alcohol (mass).

(2) alkaline substance layer 3

Next, the basic substance layer 3 is formed into a solution, and applied to the adhesive layer 2 in the same manner as described above, and dried. The basic substance layer 3 is formed in a solution, and the basic substance concentration is preferably 0.5% by mass to 3.5% by mass, preferably 1.0% by mass to 3.0% by mass. In addition, the concentration of the basic substance or the like is preferably adjusted to an appropriate value in accordance with the content of the reducing saccharide contained in the redox pigment layer 4 or the like. Water is used as a solvent. As the alkaline substance, as described above, an alkali metal salt can be used, and in particular, a carbonate using an alkali metal such as sodium carbonate or potassium carbonate is preferred.

(3) redox pigment layer 4

Next, the redox pigment layer 4 is formed into a solution, and applied to the alkaline material layer 3 in the same manner as described above, and dried. The redox pigment layer 4 forming solution can be prepared by dissolving a reducing agent in water as a solvent and dissolving or dispersing the redox dye. As described above, as the reducing agent, it is preferred to use a reducing saccharide, particularly preferably D-glucose.

In the redox dye layer 4 forming solution, the redox pigment concentration is preferably 0.1% by mass to 3.0% by mass, more preferably 0.3% by mass to 2% by mass, even more preferably 0.5% by mass to 1.5% by mass.

In the redox dye forming solution, the reducing agent may be appropriately adjusted in accordance with the content of the redox dye as long as it is sufficient to maintain the redox dye in a reduced state. When D-glucose is used as the reducing agent, it is preferably from about 1% by mass to about 25% by mass, preferably from about 3% by mass to about 20% by mass, more preferably from about 5% by mass to about 15% by mass.

Further, the redox pigment layer 4 forming solution corresponds to the above aqueous ink composition. By using a printing method, the redox pigment layer 4 is formed into a solution as an ink, and when a specific character or symbol is printed on the substrate 1, a solvent for forming a solution of the redox pigment layer 4 can be used together with water. Ethanol. Since the volatility of the ethanol is good, when the redox pigment layer 4 is formed into a solution on the substrate 1 (accurately on the chlorinated substance layer), the solvent component can be quickly volatilized. At this time, glycerin may be added to the redox pigment layer 4 forming solution as necessary. By adding glycerin, the redox pigment can be favorably dispersed in an aqueous solvent. Therefore, for example, when the redox dye solution is used as an ink, when a specific character or symbol is printed on the substrate 1 by an ink jet printer or the like, the redox pigmentation can be prevented, and the ink discharge portion can be clogged. Wait. Further, in order to suppress the sedimentation of the redox pigment, a polyvinyl alcohol or a glycerin fatty acid ester or the like may be added in a small amount as a surfactant, if necessary.

Here, in the method for producing an oxygen detecting agent of the present invention, since the adhesive layer 2 is provided on the substrate 1, even if the substrate 1 is a hydrophobic substrate 1 such as polyester, the alkaline substance layer 3 forms a solution (aqueous solution). The redox pigment layer 4 forming solution (aqueous solution) has good wettability, and the basic substance layer 3 or the redox pigment layer 4 can be formed on the adhesive layer 2 with good adhesion. Therefore, for example, in the case where the aqueous ink-like composition is applied (discharged) only in a color-developing region of a specific character or shape by the printing method, leakage can be prevented. Further, as the oxygen detecting agent produced by this method, as described above, the color tone change of the redox dye is clearly visually recognized, and good color change reactivity can be obtained. Further, according to the method for producing an oxygen detecting agent of the present invention, since the solvent for forming a solution in each layer can be entirely water, and it is not necessary to use an organic solvent, the organic solvent remaining in the oxygen detecting agent volatilizes in the storage container and adheres to the food. Or the problem of pharmaceuticals does not occur and is better.

Further, after the redox pigment layer 4 is formed, an adhesion layer is formed on the redox pigment layer 4, and it is also possible to adhere to the second substrate 5 without any doubt (see FIG. 2).

Hereinafter, the examples and comparative examples will be shown and the invention will be specifically described. However, the invention of the present invention is not limited to the following embodiments.

 [Example 1]  

An adhesive layer, a basic substance layer, and a redox pigment layer were formed on a transparent film substrate (PET film) made of polyethylene terephthalate having a size of 2.5 cm × 3 cm by the following procedure. The oxygen detecting agent of Example 1.

(1) Adhesive layer formation step

In the adhesive layer forming step, as the adhesive layer forming solution, polyvinyl alcohol having an average polymerization degree of 3,500 (Grade 1 reagent / 163-16355, manufactured by Wako Pure Chemical Industries, Ltd.) was used to prepare a 5 mass% aqueous solution of polyvinyl alcohol. . Magnesium hydroxide was added to the 5 mass% aqueous polyvinyl alcohol solution. At this time, the mixing ratio of the 5% by mass aqueous solution of polyvinyl alcohol and magnesium hydroxide was 7:3. Further, the mixing ratio of the polyvinyl alcohol (solid content) to the magnesium hydroxide was 100:857.

The adhesive layer forming solution prepared as described above was applied onto the above substrate using a bar coater. After the adhesive layer is applied to form a solution, it is dried by a dryer to form an adhesive layer. Further, the bar coater for applying the adhesive layer forming solution was No. 2 (film thickness: 4.58 μm) manufactured by Daiichi Ricoh Co., Ltd.

(2) Basic substance layer forming step

In the alkaline material layer forming step, 0.15 g of sodium carbonate was dissolved in 10.0 g of water to prepare a basic substance layer forming liquid having a sodium carbonate concentration of 1.48%. This alkaline substance layer was formed into a solution on the adhesive layer, and applied in the same manner as described above using a bar coater. Thereafter, it is dried by a dryer to become a basic substance layer.

(3) Redox pigment layer formation step

In the redox dye layer formation step, 5.0 g of ethanol was mixed with 25.0 g of water to form a water-ethanol mixed solvent. To the mixed solvent, 0.3 g of methylene blue as a redox dye and 5.0 g of D-glucose as a reducing agent were added and mixed. The methylene blue concentration was 0.85 mass%, and the D-glucose concentration was 14.16 mass%. This redox pigment layer was formed into a solution on the alkaline material layer, and coated in the same manner as described above using a bar coater. Thereafter, it was dried by a dryer to form a redox pigment layer.

(4) After that, the coated surface was turned over, and the surface of the deoxidizing agent (Powdertech Co., Ltd.: Wonderkeep (registered trademark) LP-100) was adhered and fixed to the redox dye layer side, and the transparent resin substrate side was placed. As a visual recognition surface. Then, eight x 11 columns of pinholes were opened on the transparent resin substrate to serve as an oxygen detecting agent of Example 1.

 [Example 2]  

An oxygen detecting agent was produced in the same manner as in Example 1 except that a biaxially oriented polypropylene film (OPP film) was used as the transparent resin substrate.

 [Example 3]  

An oxygen detecting agent was produced in the same manner as in Example 1 except that an OHP film (BFSA4C manufactured by Quick Art Co., Ltd.) having a thickness of 60 μm was used as the transparent resin substrate. The OHP film is subjected to a water-absorbent PET film.

 [Comparative Example 1]  

In Comparative Example 1, when an adhesive layer was formed, an oxygen detecting agent was produced in the same manner as in Example 1 except that magnesium hydroxide was not used.

 [Comparative Example 2]  

In Comparative Example 2, in the adhesive layer forming step, aluminum hydroxide was used instead of magnesium hydroxide. The mixing ratio of the 5% by mass aqueous solution of polyvinyl alcohol to the aluminum hydroxide in the adhesive layer forming solution was 8:2. Further, the mixing ratio of polyvinyl alcohol (solid content) to aluminum hydroxide is 100:500 by mass.

Further, in the redox pigment layer forming step, 5.0 g of ethanol was mixed with 10.0 g of water to form a water-ethanol mixed solvent. To the mixed solvent, 0.1 g of methylene blue as a redox dye and 1.0 g of D-glucose as a reducing agent were added. Further, as the surfactant, 0.05 g of polyvinyl alcohol having an average degree of polymerization of 500 was added. The above was mixed to prepare a redox pigment liquid forming solution having a methylene blue concentration of 0.62% by mass and a D-glucose concentration of 6.19% by mass. An oxygen detecting agent was produced in the same manner as in Example 1 except that the above-described adhesive layer forming solution and redox pigment layer forming solution were used to form an adhesive layer and a redox pigment layer.

 [Comparative Example 3]  

In Comparative Example 3, an oxygen detecting agent was produced in the same manner as in Comparative Example 2, except that the same OPP film as in Example 2 was used as the transparent resin substrate.

 [Comparative Example 4]  

In Comparative Example 4, an oxygen detecting agent was produced in the same manner as in Comparative Example 2, except that the same OHP film as in Example 3 was used as the transparent resin substrate.

 【Evaluation】  

Evaluation method

(1) Adhesion, stain

The state after the formation of the adhesive layer, the basic substance layer, and the redox pigment layer on the substrate was visually confirmed, and the adhesion of the layers to the substrate and the presence or absence of color unevenness were confirmed.

(2) Color change reactivity

The oxygen detecting agent integrated with the deoxidizing agent prepared in each of the examples and the comparative examples was placed in a polydichloroethylene-coated nylon polyethylene bag having a width of 150 mm and a length of 200 mm, and sealed in a thermostat at 35 ° C. Save for 12 hours. Then, the color change of the oxygen detecting agent over time after the opening was visually confirmed, and the reflection spectrum was measured to confirm the change in the peak intensity. Further, in the measurement of the reflection spectrum, an ultraviolet-visible spectrophotometer V-570 manufactured by JASCO Corporation was used.

(3) Reusability

The oxygen detecting agent prepared in the same manner as in Example 1 was placed in a polydivinylidene-coated nylon polyethylene bag having a width of 150 mm and a length of 200 mm, and a deoxidizing agent (Powdertech Co., Ltd.: Wonderkeep (registered trademark) LP- 100) Also loaded together, sealed, and stored in a thermostat at 35 ° C for 12 hours. Thereafter, it was opened, and the color change of the oxygen detecting agent was confirmed 5 minutes after the opening, 10 minutes later, and 30 minutes later. Until the color of the oxygen detecting agent is not changed, the oxygen detecting agent placed in an oxygen atmosphere is again placed in the bag together with the new deoxidizing agent, and the coloring of the oxygen detecting agent is confirmed by the same procedure as above. The steps to change. The number of repetitions is 9.

2. Evaluation results

(1) Adhesion and stain

First, the oxygen detecting agents of Example 1 and Comparative Example 1 are described. In the oxygen detecting agent of Example 1, the adhesive layer contains polyvinyl alcohol and magnesium hydroxide. In the oxygen detecting agent of Example 1, each layer was formed on the surface of the base material made of polyethylene terephthalate with good adhesion, and the color of the redox pigment layer was also excellent, and no stain was observed. . On the other hand, in the oxygen detecting agent of Comparative Example 1, the adhesive layer was formed using only a polyvinyl alcohol aqueous solution. In other words, the adhesive layer does not contain magnesium hydroxide. In the oxygen detecting agent of Comparative Example 1, although the respective layers may be formed on the surface of the polyethylene terephthalate substrate, the redox pigment layer or the like may not be formed in a uniform thickness, or may be attached. If the sex is insufficient, the stain will be observed before deoxidation.

In Comparative Example 2, aluminum hydroxide as a substituted magnesium hydroxide as an adhesive layer was contained. By adding aluminum hydroxide to the adhesive layer, the adhesion between the basic substance layer and the redox pigment layer was better than that of Comparative Example 1, and the number of spots was small. However, compared with the oxygen detecting agent of Example 1 containing magnesium hydroxide in the adhesive layer, the adhesion was low, and staining was observed.

The oxygen detecting agents of Examples 2 and 3 were produced in the same manner as in Example 1 except that the materials of the substrates were different. Each of the layers can be formed with good adhesion on each of the substrates, and the adhesive layer can be made of a structure containing polyvinyl alcohol and magnesium hydroxide, and a substrate having no water absorption such as a PET film or an OPP film can be used. In this case, it is also possible to use a redox pigment layer forming solution prepared in the form of a water-based ink on the substrate, and it is confirmed that a printed oxygen detecting agent can be produced.

On the other hand, when comparing Comparative Example 2 to Comparative Example 4, the oxygen detecting agent of Comparative Example 4 using the OHP film as the substrate was compared with the oxygen detecting agent of Comparative Example 2 and Comparative Example 3 in the adhesive layer. When magnesium hydroxide is substituted and aluminum hydroxide is added, the redox pigment layer is thin and can be formed with good adhesion. The OHP film is subjected to a water absorbing treatment on the surface of the PET film. Since the water absorption of the substrate is higher than that of the other substrate (PET film/OPP film), it is presumed that the redox pigment layer can be formed on the substrate with good adhesion.

(2) Reflection spectrum

In the third and fourth figures, the reflectance spectra measured for the oxygen detecting agents of Example 1 and Comparative Example 1 are shown. The oxygen detecting agent of Example 1 showed a blue-violet color before deoxidation, and showed a peak at a position of 588 nm and a wavelength of 663 nm. After 12 hours of storage with the deoxidizer in the sealed bag, as shown in Fig. 3f, the absorbance in the visible light region was about 0.01, which was white (color of the adhesive layer). On the other hand, the peak intensity at the same position before deoxidation was about 6.0. After the sealed bag was opened, the peak intensity after 5 minutes passed was about 1.0, which was about 15% of the peak strength before deoxidation. Further, the peak intensity after 30 minutes of unsealing was about 3.0, which was about 50% of the peak intensity before deoxidation. The peak intensity at the same position after opening for 1 hour was about 5.0, which was about 80% before deoxygenation. It was confirmed that the oxygen in the ambient gas was visually distinguishable after 5 minutes, and it was confirmed that good discoloration reactivity was ensured.

On the other hand, the oxygen detecting agent of Comparative Example 1 showed a blue color before deoxidation, and showed a peak at a position of a wavelength of 610 nm and a wavelength of 664 nm. After 12 hours of storage with the deoxidizer in the sealed bag, as shown in Fig. 4f, the absorbance in the visible light region was about 0.01, which was colorless. On the other hand, the peak intensity at the same position before deoxidation was about 8.0. After the sealed bag was opened, the peak intensity after 5 minutes passed was about 0.07, the peak intensity after 30 minutes of opening was about 0.3, and the peak intensity at the same position after opening for 1 hour was about 0.6. Even after standing for 1 hour in an oxygen atmosphere, only the peak intensity of 10% or less before deoxidation was exhibited, and it was confirmed that the oxygen detecting agent had lower discoloration reactivity than that of Example 1.

Next, Fig. 5 shows the reflection spectrum measured for the oxygen detecting agent of Comparative Example 2. The oxygen detecting agent of Comparative Example 2 showed a blue color before deoxidation, and showed a peak at a position of a wavelength of 606 nm and a wavelength of 666 nm. After 12 hours of storage with the deoxidizer in the sealed pouch, as shown in Fig. 5f, the absorbance in the visible light region was about 0.01, which was white (color of the adhesive layer). On the other hand, the peak intensity at the same position before deoxidation was about 9.0. After the sealed bag was opened, the peak intensity after 5 minutes passed was about 1.0, which was about 15% of the peak strength before deoxidation. Further, the peak intensity after 30 minutes of unsealing was about 2.0, which was about 22% of the peak intensity before deoxidation. Compared with Comparative Example 1, although the color change reactivity of the oxygen detecting agent of Comparative Example 2 was improved, the color change reactivity was lower than that of Example 1, and it was presumed that the redox reaction of the redox dye was rapid. Adequate conditions (water retention, pH, etc.) are insufficient.

Further, as shown in the above FIGS. 3 to 5, the reflection spectrum has peaks at two wavelength positions. The peak on the long wavelength side indicates the peak of the monomer of methylene blue, and appears at about 663 nm to 666 nm. On the other hand, the peak on the short-wavelength side indicates the peak of the dimer of methylene blue, and it was confirmed that the peak position changes as the concentration of methylene blue becomes higher, that is, the higher the peak intensity, the shorter the wavelength side. The higher the concentration of methylene blue, the easier it is to produce aggregates such as trimers or tetramers. Therefore, it is presumed that the shift of the peak position is observed.

Further, when the solution for forming the adhesive layer was prepared, an oxygen detecting agent was produced in the same manner as in Example 1 except that magnesium hydroxide, magnesium oxide, sodium hydroxide, potassium hydroxide or the like was used instead of magnesium hydroxide. However, when calcium hydroxide, sodium hydroxide or potassium hydroxide is used, the browning reaction of D-glucose used as a reducing agent occurs, and not only the redox pigment layer is brownish, but also the redox pigment is difficult to maintain in the reduced form. . Therefore, it is difficult to obtain a practical oxygen detecting agent. Further, when magnesium oxide is used, when the magnesium oxide is added to the aqueous polyvinyl alcohol solution, the adhesive layer forming solution is immediately gelated, and it is difficult to apply the adhesive layer forming solution thinly and uniformly on the substrate.

On the other hand, in the case of magnesium hydroxide, even if magnesium hydroxide is added to the polyvinyl alcohol, the adhesive layer forming solution does not immediately gel, and the adhesive layer forming solution can be thinly coated on the substrate, and further Ensure full operability. Further, if the polyvinyl alcohol is used only when the solution for forming the adhesive layer is dried, the adhesive layer is cured faster. Therefore, it is presumed that by adding magnesium hydroxide to the adhesive layer, the crosslinking density of the polyvinyl alcohol is slightly increased, and the redox reaction of the redox dye proceeds well, thereby ensuring sufficient water retention and at the same time It functions as a bonding layer for adhesion to a substrate and a basic substance layer and a redox pigment layer.

Further, when the oxygen detecting layer is formed on the substrate via the adhesive layer, as described in the above embodiment and the present embodiment, after the alkaline substance layer is formed on the adhesive layer, the redox dye is formed on the basic substance layer. As the layer, an oxygen detecting agent having good color change reactivity and good color development can be obtained. On the other hand, when the alkaline substance, the reducing agent, and the vaporized reducing dye are all formed on the gas detecting layer of one layer on the adhesive layer, the color change reactivity and the display are compared with the case where the oxygen detecting layer has a two-layer structure. The color features are insufficient. In the case where the reducing agent (D-glucose) is contained in the alkaline substance layer, the browning reaction of the reducing saccharide is one of the causes of the change in color change reactivity and color development. On the other hand, as described in the above embodiment and the present embodiment, the basic substance layer is a layer containing only the basic substance, and the redox pigment layer containing the reducing agent is formed on the basic substance layer, thereby suppressing A browning reaction of a reducing agent (D-glucose), and an excellent oxygen detecting agent with good color change reactivity and color development can be obtained.

Further, from the viewpoint of forming a basic substance layer and a redox pigment layer which are excellent in adhesion on a substrate, the OHP film is superior to the PET film and the OPP film. However, from the viewpoint of obtaining more pronounced color tone change and rapid color change reactivity, it was confirmed that it is most preferable to use a PET film as a substrate.

(3) Reusability

When the color change of the oxygen detecting agent of Example 1 was repeated 9 times, as shown in Fig. 6, the oxygen detecting agent of Example 1 was stored in the thermostat for 12 hours even after the ninth time, and the oxygen was confirmed. The detection agent is white, and methylene blue has a reduced structure. Further, even when the oxygen detecting agent was placed in an oxygen atmosphere after the ninth opening, the oxygen detecting agent became dark blue with time, and the coloration after 30 minutes passed was equivalent to the degree of the first time. From this, it is understood that the oxygen detecting agent of Example 1 does not deteriorate even when it is repeatedly used a plurality of times, and it is understood that it is possible to detect the presence or absence of oxygen in the ambient gas.

 (industry availability)  

According to the invention of the present invention, it is possible to provide an oxygen detecting agent and a method for producing the oxygen detecting agent which are excellent in surface color adhesion of a hydrophobic substrate while ensuring a remarkable color tone change and good color change reactivity.

Claims (7)

 An oxygen detecting agent which is attached to a substrate to form an adhesive layer containing magnesium hydroxide and an adhesive; and an oxygen detecting layer containing a redox dye which changes color tone depending on the presence or absence of oxygen in the ambient gas, from the substrate The sides are stacked in this order.    The oxygen detecting agent according to the first aspect of the invention, wherein the oxygen detecting layer has a basic substance layer containing a basic substance; and a redox coloring layer containing a reducing agent and the redox dye. A two-layer structure in which the layers are stacked in this order from the substrate side on the adhesive layer.    The oxygen detecting agent according to claim 1 or 2, wherein the substrate is a transparent resin substrate.    The oxygen detecting agent according to claim 1 or 2, wherein the adhesive is polyvinyl alcohol.    The oxygen detecting agent according to claim 2, wherein the alkaline substance is sodium carbonate.    The oxygen detecting agent according to claim 2, wherein the reducing agent is a reducing saccharide.    A method for producing an oxygen detecting agent, which is a method for producing an oxygen detecting agent capable of detecting the presence or absence of oxygen in an ambient gas by a change in color tone of a redox dye, comprising: forming magnesium hydroxide and an adhesive on a substrate a step of adhering the layer; and forming, on the adhesive layer, a step of forming an oxygen detecting layer of a redox dye having a change in color tone depending on the presence or absence of oxygen in the ambient gas.