JP2018128391A - Oxygen detecting agent and manufacturing method of oxygen detecting agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oxygen detecting agent capable of ensuring sharp color change and satisfactory discoloration response with satisfactory adhesion even on the surface of hydrophobic base material, and manufacturing method of the oxygen detecting agent.SOLUTION: The oxygen detecting agent has a binder layer which contains magnesium hydroxide and binding agent on a base material and an oxygen sensing layer which contains redox dye which changes the color tone depending on the presence or absence of oxygen in the atmosphere, which are laminated in this order from the base material side. When preparing the oxygen detecting agent, the binder layer and the oxygen sensing layer are laminated in order on the base material.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to an oxygen detector and a method for producing the oxygen detector that make it possible to visually recognize a change in the amount of oxygen in the atmosphere by a change in color tone, and in particular, an oxygen detector having a laminated structure and a method for producing the oxygen detector. About.

  When storing foods and medicines, oxygen in the atmosphere oxidizes the foods and medicines and degrades the quality of the foods and medicines. Therefore, in order to prevent quality degradation during storage, food and pharmaceuticals etc. are put in a container package together with an oxygen scavenger and sealed, and oxygen in the container pack is absorbed by the oxygen scavenger etc. Preserving foods, pharmaceuticals, etc. (refers to a state where the oxygen concentration is 0.1% or less).

  In recent years, it has been performed to enclose an oxygen detector together with an oxygen scavenger in a container package and detect the presence or absence of oxygen in the container package with the oxygen detector. The oxygen detector makes it possible to visually recognize the presence or absence of oxygen in the hermetic container packaging by changing the color tone. The user can easily confirm whether or not foods, medicines, and the like are stored in a deoxygenated state based on the color tone exhibited by the oxygen detector.

  This type of oxygen detector is generally configured to include a reducing agent, a basic substance, and a redox dye having different colors in an oxidized state and a reduced state. The reducing agent is used to keep the redox dye in a reduced state when the atmosphere is in a deoxygenated state. As described above, the oxygen detector detects oxygen using a mechanism in which the redox dye held in a reduced state is oxidized by oxygen in the atmosphere and changes its color tone. Therefore, the oxygen detecting agent is required to have a clear color tone change and a good color change responsiveness accompanying a change in the amount of oxygen in the atmosphere.

  Conventionally, as such an oxygen detector, a tablet-type oxygen detector formed into a tablet or a sheet-type oxygen detector obtained by impregnating a sheet-like carrier such as paper with an oxygen detection composition solution is used. I came. In such a conventional oxygen detection agent, since it is necessary to individually wrap the oxygen detection agent in the form of a tablet or a sheet, there is a problem that the manufacturing process of the oxygen detection agent is complicated. Moreover, when using an oxygen detection agent, it is necessary to enclose an oxygen detection agent in a container package with a deoxidation agent, and the effort is required. In view of this, a product that integrates the oxygen scavenger and the oxygen detector by attaching an oxygen detector individually wrapped on the surface of the packaging material of the oxygen scavenger has been proposed. However, in this case, there is a problem that the manufacturing process of the product becomes very complicated.

  On the other hand, in recent years, so-called printing type oxygen detectors have been proposed (see, for example, Patent Document 1). A printing type oxygen detector may be realized by, for example, applying or printing an oxygen detection composition on a container / wrapping material itself such as food or medicine, so that individual packaging of the oxygen detector is not required. In addition, the process of encapsulating the oxygen detection agent in the container package can be reduced. It can also be realized by applying or printing the oxygen detector composition on the packaging material of the oxygen absorber, which greatly simplifies the manufacturing process of the product integrating the oxygen absorber and the oxygen detector. it can.

Japanese Patent Laid-Open No. 2006-75546

  Here, the color tone change accompanying the redox reaction of the redox dye is performed in a system using water as a medium. Therefore, the oxygen detector composition contains moisture. Since the oxygen detection agent described in Patent Document 1 uses a paper base material, the oxygen detection agent composition is impregnated into the base material. However, when a base material that does not have water absorption, such as a plastic film, is used, it is difficult to apply or print the oxygen detector composition on the surface of the substrate when the water content in the oxygen detector composition increases. Thus, it becomes difficult to produce a printing type oxygen detector having good adhesion to the substrate.

  An object of the present invention is to provide an oxygen detector having good adhesion even on the surface of a hydrophobic substrate and a method for producing the oxygen detector, while ensuring a clear color change and good discoloration response. It is in.

  In order to solve the above problems, an oxygen detector according to the present invention is a redox that changes a color tone depending on the presence or absence of oxygen in the atmosphere, a binder layer containing magnesium hydroxide and a binder on a base material. An oxygen detection layer containing a sex pigment is laminated in that order from the substrate side.

  In the oxygen detecting agent according to the present invention, the oxygen detecting layer includes a basic substance layer containing a basic substance, a reducing agent, and a redox dye layer containing the redox dye on the binder layer. It is preferable to have a two-layer structure laminated in this order from the substrate side.

  In the oxygen detection agent according to the present invention, the base material is preferably a transparent resin base material.

  In the oxygen detection agent according to the present invention, the binder is preferably polyvinyl alcohol.

  In the oxygen detection agent according to the present invention, the basic substance is preferably sodium carbonate.

  In the oxygen detection agent according to the present invention, the reducing agent is preferably a reducing saccharide.

  In order to solve the above-mentioned problem, a method for producing an oxygen detector according to the present invention is a method for producing an oxygen detector capable of detecting the presence or absence of oxygen in an atmosphere by a change in color tone of a redox dye, On top, a step of forming a binder layer containing magnesium hydroxide and a binder, and an oxygen detection layer containing a redox dye that changes color depending on the presence or absence of oxygen in the atmosphere are formed on the binder layer. And a step of performing.

  According to the present invention, it is possible to provide an oxygen detector having good adhesion even on the surface of a hydrophobic substrate and a method for producing the oxygen detector while ensuring a clear color tone change and good discoloration response. Can do.

It is a schematic diagram which shows the layer structure of the oxygen detection agent of embodiment of this invention. It is a schematic diagram which shows the layer structure of the oxygen detection agent of the other form of this invention. It is a figure which shows the time-dependent change of the reflection spectrum when the oxygen detection agent of Example 1 is made into an aerobic state from a deoxygenation state. It is a figure which shows a time-dependent change of the reflection spectrum when the oxygen detection agent of the comparative example 1 is made into an aerobic state from a deoxygenation state. It is a figure which shows a time-dependent change of the reflection spectrum when the oxygen detection agent of the comparative example 2 is made into an aerobic state from a deoxygenation state. It is a figure which shows the color change when the oxygen detection agent of Example 1 is used repeatedly.

  Hereinafter, preferred embodiments of the oxygen detector and the method for producing the oxygen detector according to the present invention will be described.

1. Oxygen detection agent The layer structure of the oxygen detection agent of this Embodiment is typically shown in FIG. As shown in FIG. 1, the oxygen detector according to the present embodiment includes a binder layer 2 containing magnesium hydroxide and a binder, a basic substance layer 3 containing a basic substance, and a base material 1. The redox dye layer 4 containing the reducing agent and the redox dye is laminated in this order from the substrate 1 side. The oxygen detector can visually recognize a change in the amount of oxygen in an atmosphere (hereinafter referred to as “oxygen-detected atmosphere”) in a container / package containing food, medicine, etc., by changing the color tone of the redox dye. It is a thing. In the oxygen detection agent of the present embodiment, the oxygen detection function is expressed by the two layers of the basic substance layer 3 and the redox dye layer 4. However, the oxygen detector according to the present invention is a redox dye that changes its color tone depending on the presence or absence of oxygen in the atmosphere via the binder layer 2 on the substrate 1 or a reduction that keeps the reducing dye in a reduced state. As long as an oxygen detection layer composed of an oxygen detection composition containing an agent or the like is provided, each component constituting the oxygen detection composition may be divided into a plurality of layers as in the present embodiment, All components constituting the oxygen detection composition may be arranged in one layer, and the specific configuration is not particularly limited. Hereinafter, each layer will be described. Hereinafter, the two layers of the basic substance layer 3 and the redox dye layer 4 may be referred to as an oxygen detection layer.

(1) Base material 1
In this invention, although the base material 1 is not specifically limited, For example, the paper base material 1, the resin base material 1 etc. can be used, The shape is not specifically limited. In particular, the substrate 1 is preferably a paper container packaging material or a resin container packaging material molded into various shapes such as a film shape, a packaging bag shape, and a packaging container shape. The oxygen detection agent according to the present invention can be formed on the surface of the substrate 1 by, for example, applying or printing an ink-like composition for forming the oxygen detection layer. Therefore, the container packaging material with an oxygen detection function can be easily obtained by the printing method etc. by using the container packaging material as the base material 1.

  In the oxygen detector according to the present invention, the base material 1 is more preferably a transparent resin base material 1. By providing the oxygen detection layer via the binder layer 2 on the transparent resin substrate 1, the color tone change of the redox dye can be visually recognized from the transparent resin substrate 1 side. Therefore, when the oxygen detection agent is used, if the base material 1 side faces the oxygen detection atmosphere, the oxygen detection of the stored product such as food and medicine in the oxygen detection atmosphere and the redox dye and the like. Contact with the components of the composition can be prevented.

  As the transparent resin base material 1, for example, a resin base material 1 made of polyester, polyethylene, polypropylene, polyamide or the like can be used. In order to detect the presence or absence of oxygen in the oxygen-detecting atmosphere via the base material 1, the base material 1 is required to have oxygen permeability. Therefore, when using the transparent resin substrate 1 made of polyester, polyamide, or the like having a small oxygen permeation amount, a perforated transparent resin having very small pores capable of ensuring waterproofness and oilproofness while ensuring air permeability. The substrate 1 is preferably used. More specifically, for such a transparent resin substrate 1, as polyester, polyethylene terephthalate (PET), as polyethylene, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), as polypropylene, unstretched Polypropylene (CPP), biaxially oriented polypropylene (OPP), or the like can be used. These synthetic resin films may be used not only as a single layer film but also as a laminated film in which films of different materials are laminated.

  In the oxygen detector according to the present invention, even when a hydrophobic base material 1 such as polyester is used, the basic substance layer 3 and the redox dye layer 4 are separated from each other through the binder layer 2 described below. The oxygen detection layer to be formed can be provided on the substrate 1 with good adhesion. In the present embodiment, the oxygen detector according to the present invention will be described mainly using the case where the transparent resin substrate 1 is used as an example. However, as described above, the base material 1 is not particularly limited in the present invention. The base material 1 is not limited to the transparent resin base material 1, and an opaque resin base material 1 may be used. May be. In addition, the hydrophilic treatment may be given to the surface by which the oxygen detection layer of the base material 1 is provided.

(2) Binder layer 2
Next, the binder layer 2 will be described. The binder layer 2 is a layer containing magnesium hydroxide and a binder. The binder layer 2 is preferably made of a mixture of magnesium hydroxide fine particles and a binder, and the magnesium hydroxide fine particles are preferably dispersed in the binder. By dispersing particulate magnesium hydroxide in the binder, the binder layer 2 exhibits a white color. By providing a white layer on the base material 1, the color tone change of the redox dye can be clearly visible.

  A binder is a component for making the base material 1 and each component which comprises an oxygen detection layer closely_contact | adhere. As will be described later, the oxygen detector according to the present invention can be produced by a method of applying or printing an aqueous ink-like composition dissolved or dispersed in an aqueous solvent containing the constituent components of each layer on the substrate 1. . When the base material 1 is a hydrophobic transparent resin base material 1, when the aqueous ink-like composition is directly applied or printed on the base material 1, the wettability of the aqueous ink-like composition with respect to the base material 1 is poor, It becomes difficult to apply or print the water-based ink-like composition on the substrate 1 with a uniform thickness. However, according to the present invention, by providing the binder layer 2 on the base material 1, the wettability of the aqueous ink-like composition on the surface of the base material 1 can be improved.

  Therefore, the aqueous ink-like composition can be satisfactorily applied or printed on the surface of the binder layer 2 with a uniform thickness, and the basic substance layer 3 having good adhesion via the binder layer 2 on the substrate 1. In addition, a redox dye layer 4 can be provided. Therefore, the redox dye can be uniformly distributed over the entire coloring region on the substrate 1, and uniform color development can be realized without color unevenness.

  Here, it is preferable to use a water-soluble resin as a binder. Examples of water-soluble resins include polyvinyl alcohol (PVA), acrylic resins, and various modified resins into which hydrophilic groups such as hydroxyl groups have been introduced. By using a water-soluble resin as a binder, water can be used as a solvent when the binder layer 2 is formed. If there is a step of using an organic solvent in the production process of the oxygen detector, the remaining organic solvent may volatilize in the storage container and adhere to food or medicine. If a water-soluble resin is used as a binder, it is not necessary to use an organic solvent.

  Further, the color tone change accompanying the redox reaction of the redox dye is performed in a system using water as a medium. By providing the binder layer 2 containing a water-soluble resin as a binder, it is possible to easily retain the moisture necessary for the redox reaction of the redox dye on the substrate 1. Therefore, unlike the prior art, an oxygen detector having a good color change responsiveness can be realized on the hydrophobic substrate 1 without using a carrier such as the hydrous substrate 1 or porous silica. In particular, since polyvinyl alcohol has a high proportion of hydroxyl groups contained in the molecular structure, if polyvinyl alcohol is used as a binder, the water required for the oxidation-reduction reaction can be easily held in the binder layer 2, and quick discoloration response. It is possible to obtain an oxygen detector having

  On the other hand, when a water-soluble resin is used as a binder, the water-soluble resin in the binder layer 2 is contained in the water-based ink composition when the water-based ink composition is applied or printed on the binder layer 2. There is a risk of dissolution. However, in the present invention, by dispersing magnesium hydroxide in the binder layer 2, compared with the case where magnesium hydroxide is not included, the redox reaction of the redox dye can be performed well, It is considered that the water retention of the binder layer is improved because the color change responsiveness is obtained. In addition, when a water-based ink composition is applied or printed on the surface of the binder layer 2, an effect of preventing the water-soluble resin constituting the binder layer 2 from being dissolved in water contained in the water-based ink composition is expected. it can.

  In addition, it is good also as a structure containing glycerin from a viewpoint of raising the water retention of the binder layer 2, for example. When the glycerin content increases, it becomes difficult to solidify the binder layer. Therefore, it is necessary to adjust the glycerin content to an amount that does not hinder the solidification of the binder layer.

(3) Basic substance layer 3
In the oxygen detector of the present embodiment, reducing saccharide is used as a reducing agent for maintaining the redox dye in a reduced state in an oxygen-free atmosphere. The reducing saccharide is ring-opened in an aqueous solution, and an aldehyde having a reducing group becomes a ring-opened product. However, this ring-opened compound does not act as a reducing agent for redox dyes in a neutral aqueous solution, but acts as a reducing agent for redox dyes under alkaline conditions. Therefore, a basic substance (alkaline agent) is required to reduce the redox pigment by the reducing saccharide. Therefore, the oxygen detection agent of the present embodiment is provided with a basic substance layer 3 containing a basic substance on the substrate 1.

  As the basic substance, for example, an alkali metal salt can be used, and in particular, an alkali metal carbonate such as sodium carbonate or potassium carbonate is preferably used. Alkali metal hydroxides such as sodium hydroxide and potassium hydroxide can also be used. However, these are strong bases, so that the browning reaction of the reducing saccharide is easily caused. Therefore, it is more preferable to use an alkali metal carbonate which is a weak base. Further, in the oxygen detection agent of the present embodiment, the oxygen detection layer has a two-layer structure of the basic substance layer 3 and the redox dye layer 4, and the redox dye layer 4 contains the reducing dye. By doing so, the browning reaction of a reducing pigment can be made harder to occur.

(4) Redox dye layer 4
In the oxygen detection agent of the present embodiment, the redox dye layer 4 includes a reducing agent and the redox dye.

  A redox dye is a dye that is reduced by a reducing agent and reversibly changes color between an oxidized state and a reduced state. Examples of such pigments include methylene blue, new methylene blue, phenosafranine, rous violet, and methylene green. For example, in the case of methylene blue, when the oxygen detection atmosphere is in a deoxygenated state, it has a reduced structure (leucomethylene blue) and exhibits colorlessness. On the other hand, when the oxygen sensing atmosphere is in an aerobic state, methylene blue has an oxidized structure and exhibits blue.

  As the reducing agent, reducing saccharides can be used. Specifically, monosaccharides such as D-mannose, D-glucose, D-fructose, D-erythrose and D-altrose, reducing disaccharides such as maltose and lactose, maltotriose, cellotriose, manninotri Reducing trisaccharides such as ose and vanose can be used. Among these, it is particularly preferable to use a monosaccharide as compared with the reducing disaccharide and the reducing trisaccharide from the viewpoint of high reactivity and high reduction power for the redox dye. Among monosaccharides, D-glucose can be used more preferably. This is because D-glucose can easily obtain a product with high purity (for example, a purity of 99% or more) at low cost on the market. In addition to reducing sugars, ascorbic acid or the like can also be used as the reducing agent.

  The oxygen detector of the present embodiment includes, for example, the binder layer 2, the basic substance layer 3, and the redox dye layer 4 only on a predetermined color development region such as letters or symbols on the substrate 1. It is intended to make it possible to visually recognize the presence or absence of oxygen by changing the color tone of a color-developing region having a predetermined shape depending on the presence or absence of oxygen. For example, if a coloring matter that is colorless in a reduced state such as methylene blue or phenosafranine is used, characters or symbols can appear only when oxygen is present in the oxygen detection atmosphere.

  However, the oxygen detector according to the present invention adds a dye that is not reduced by the reducing agent to the oxygen detection layer, like a conventional type oxygen detector formed in a tablet or sheet form, Different colors may be exhibited depending on the presence or absence of oxygen. For example, when methylene blue is used as the redox dye, it may be possible to add food red to the oxygen detection layer. In that case, when the oxygen detection atmosphere is in a deoxygenated state, the oxygen detection layer exhibits red due to red food, and when the oxygen detection atmosphere is in an aerobic state, the oxygen detection layer exhibits blue to bluish purple. In this way, the color may be changed depending on the presence or absence of oxygen in the oxygen detection atmosphere.

(5) Second substrate 5
The oxygen detector of the present embodiment described above may be used in another form, for example, with the redox dye layer 4 side in close contact with the second substrate 5 as shown in FIG. . As the second substrate 5, the same material as the substrate 1 described above can be used. As the second substrate 5, for example, a packaging material for oxygen scavengers, a packaging material for foods and pharmaceuticals, and the like can be used.

  At this time, if an adhesive layer is provided on the surface of the redox dye layer 4 and the oxygen detector is processed into a seal shape, the oxygen detector cut out to a predetermined size is used as a packaging material for the oxygen absorber. It can be easily affixed to packaging materials such as foods and pharmaceuticals. By using the oxygen detector processed into a seal in this way, a product in which the oxygen scavenger and the oxygen detector are integrated can be easily manufactured. In addition, if the oxygen detection agent is affixed to a packaging material such as food or medicine in advance, it is possible to reduce the trouble of enclosing the oxygen detection agent in the packaging container when packaging food or medicine.

2. Next, an embodiment of a method for producing an oxygen detector according to 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 atmosphere by a change in the color tone of a redox dye. And a step of forming a binder layer 2 containing a binder, and a step of forming on the binder layer 2 an oxygen detection layer containing an oxidation-reduction dye that changes color tone depending on the presence or absence of oxygen in the atmosphere. It is characterized by providing.

  The binder layer 2 and the oxygen detection layer are as described above, and in the present embodiment, the oxygen detection layer has the two-layer structure of the basic substance layer 3 and the redox dye layer 4 as described above. .

Hereinafter, the formation method of each layer is demonstrated concretely.
(1) Binder layer 2
First, the binder layer 2 forming solution is applied onto the substrate 1 and dried using a bar coater or the like so as to have a predetermined thickness. The binder layer 2 forming solution can be prepared by dissolving a binder in a solvent and dispersing magnesium hydroxide in the solvent. The mixing ratio (mass mixing ratio) of the binder and magnesium hydroxide is preferably 100 to 2000 when the binder amount (solid content) is 100, and 400 to 1500. More preferably, it is more preferably 600-1200. As described above, it is preferable to use a water-soluble resin, particularly polyvinyl alcohol, as the binder. At this time, it is preferable to use water as a solvent. In addition, it is preferable to adjust suitably the viscosity of the binder layer 2 formation solution in view of workability at the time of coating on the substrate 1.

  However, since the preferable range of the mixing ratio of the binder and magnesium hydroxide varies depending on the degree of polymerization of the resin used as the binder, the mixing ratio is not limited to the above, and can be adjusted as appropriate.

  Even if the binder layer 2 forming solution is applied onto the substrate 1 and then dried, a certain amount of moisture is retained. For example, when polyvinyl alcohol is used as the binder, it is considered that water having a mass of about 5% to 15% of the mass of polyvinyl alcohol is retained. In addition, as above-mentioned, it is good also as a structure containing glycerol from a viewpoint of raising the water retention of the binder layer 2. As shown in FIG. However, when the glycerin content in the binder layer 2 forming solution is increased, the binder layer 2 is not solidified even if the binder layer 2 forming solution is applied and dried. Therefore, when adding glycerol, it is preferable to set it as 5 mass% or less with respect to polyvinyl alcohol (mass).

(2) Basic substance layer 3
Next, the basic substance layer 3 forming solution is applied onto the binder layer 2 and dried as described above. In the basic substance layer 3 forming solution, the basic substance concentration is preferably 0.5% by mass to 3.5% by mass, and more preferably 1.0% by mass to 3.0% by mass. In addition, it is preferable to adjust basic substance density | concentration etc. to a suitable value suitably according to content etc. of the reducing saccharide contained in the redox dye layer 4. Water is used as the solvent. As described above, an alkali metal salt can be used as the basic substance, and it is particularly preferable to use an alkali metal carbonate such as sodium carbonate or potassium carbonate.

(3) Redox dye layer 4
Next, the redox dye layer 4 forming solution is applied onto the basic substance layer 3 in the same manner as described above and dried. The redox dye 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, it is preferable to use a reducing saccharide as the reducing agent, and it is particularly preferable to use D-glucose.

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

  In the redox dye forming solution, the reducing agent may be an amount sufficient to keep the redox dye in a reduced state, and can be appropriately adjusted according to the content of the redox dye. When D-glucose is used as a reducing agent, it is preferably about 1% by mass to 25% by mass, preferably about 3% by mass to 20% by mass, and preferably about 5% by mass to 15% by mass. More preferred.

  The redox dye layer 4 forming solution corresponds to the above-described aqueous ink-like composition. When printing a predetermined character or symbol on the substrate 1 by using the redox dye layer 4 forming solution as an ink by printing, ethanol is used together with water as a solvent for the redox dye layer 4 forming solution. May be. Since ethanol has good volatility, when the oxidation-reduction dye layer 4 forming solution is printed on the substrate 1 (precisely on the chlorinated substance layer), the solvent component can be volatilized quickly. In this case, glycerin may be added to the redox dye layer 4 forming solution as necessary. By adding glycerin, the redox dye can be favorably dispersed in the aqueous solvent. Therefore, for example, when a predetermined character or symbol is printed on the substrate 1 by an ink jet printer or the like using the redox dye solution as an ink, the redox dye is precipitated and the ink discharge unit is clogged. And the like can be prevented. In order to suppress precipitation of the redox pigment, a small amount of polyvinyl alcohol, glycerin fatty acid ester or the like may be added as a surfactant if necessary.

  Here, in the method for producing an oxygen detector according to the present invention, since the binder layer 2 is provided on the base material 1, even if the base material 1 is a hydrophobic base material 1 such as polyester, the basic substance layer 3. The wettability of the forming solution (aqueous solution) and the redox dye layer 4 forming solution (aqueous solution) is good, and the basic substance layer 3 and the redox dye layer 4 are formed on the binder layer 2 with good adhesion. Can do. Therefore, for example, even when a water-based ink-like composition is applied (discharged) only to a colored region having a predetermined character or shape by printing, bleeding can be prevented. In addition, as described above, the oxygen detector produced by this method can make the change in color tone of the redox dye vividly visible and obtain a good color change responsiveness. Furthermore, according to the method for producing an oxygen detector according to the present invention, the solvent of each layer forming solution can be all water, and it is not necessary to use an organic solvent, so that the organic solvent remaining in the oxygen detector is stored. This is preferable because it does not cause a problem that it volatilizes in the container and adheres to food or medicine.

  Of course, after the redox dye layer 4 is formed, an adhesive layer may be formed on the redox dye layer 4 and adhered to the second substrate 5 described above (FIG. 2). reference).

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples.

  A binder layer, a basic substance layer, and a redox dye 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 steps. This was an oxygen detector.

(1) Binder layer forming step In the binder layer forming step, 5% by mass of polyvinyl alcohol having an average polymerization degree of 3500 (first grade reagent / 163-16355 manufactured by Wako Pure Chemical Industries, Ltd.) is used as the binder layer forming solution. A polyvinyl alcohol aqueous solution having a concentration was prepared. Magnesium hydroxide was added to this 5% by mass aqueous polyvinyl alcohol solution. At this time, the mixing ratio of 5 wt% polyvinyl alcohol aqueous solution and magnesium hydroxide was set to 7: 3 by mass ratio. In addition, the mixing ratio of polyvinyl alcohol (solid content) and magnesium hydroxide is 100: 857 in mass ratio.

  The binder layer forming solution prepared as described above was applied onto the substrate using a bar coater. After the binder layer forming solution was applied, it was dried with a dryer to obtain a binder layer. The bar coater used to apply the binder layer forming solution is a wire No. 1 manufactured by Daiichi Rika Co., Ltd. 2 (film thickness 4.58 μm) was used.

(2) Basic substance layer forming step In the basic substance layer forming step, 0.15 g of sodium carbonate was dissolved in 10.0 g of water to prepare a basic substance layer forming solution having a sodium carbonate concentration of 1.48%. . This basic substance layer forming solution was applied onto the binder layer in the same manner as described above using a bar coater. Then, it dried with the dryer and it was set as the basic substance layer.

(3) Redox dye layer forming step In the redox pigment layer forming step, 5.0 g of ethanol was mixed with 25.0 g of water to obtain 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 is 0.85% by mass, and the D-glucose concentration is 14.16% by mass. This redox dye layer forming solution was applied on the basic material layer in the same manner as described above using a bar coater. Then, it dried with the dryer and it was set as the oxidation reduction pigment layer.

(4) Thereafter, the coated surface is turned over, and the redox dye layer side is closely fixed to the surface of the oxygen scavenger (Powder Tech Co., Ltd .: Wonderkeep (registered trademark) LP-100), and the transparent resin substrate side Was the viewing surface. Then, 8 × 11 rows of pinholes were opened in the transparent resin base material to obtain the oxygen detector of Example 1.

  In Example 2, an oxygen detector was produced in the same manner as in Example 1 except that a biaxially stretched polypropylene film (OPP film) was used as the transparent resin substrate.

  In Example 3, an oxygen detector was prepared in the same manner as in Example 1 except that an OHP film having a thickness of 60 μm (BFSA4C manufactured by Quick Art Co., Ltd.) was used as the transparent resin substrate. The OHP film is a PET film that has been subjected to water absorption treatment.

Comparative example

[Comparative Example 1]
As Comparative Example 1, an oxygen detector was prepared in the same manner as in Example 1 except that magnesium hydroxide was not used when forming the binder layer.

[Comparative Example 2]
In Comparative Example 2, aluminum hydroxide was used in place of magnesium hydroxide in the binder layer forming step. The mixing ratio of 5 mass% polyvinyl alcohol aqueous solution and aluminum hydroxide in the binder layer forming solution was 8: 2. In addition, the mixing ratio of polyvinyl alcohol (solid content) and aluminum hydroxide is 100: 500 in mass ratio. In the oxidation-reduction pigment layer forming step, 10.0 g of water was mixed with 5.0 g of ethanol to obtain 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. Moreover, 0.05 g of polyvinyl alcohol having an average degree of polymerization of 500 was added as a surfactant. These were mixed to prepare a redox dye-forming solution having a methylene blue concentration of 0.62% by mass and a D-glucose concentration of 6.19% by mass. An oxygen detector was prepared in the same manner as in Example 1 except that the binder layer and the redox dye layer were formed using the binder layer forming solution and the redox dye layer forming solution.

[Comparative Example 3]
In Comparative Example 3, an oxygen detection 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 detector 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]
1. Evaluation method (1) Adhesion, color unevenness
The state after forming the binder layer, the basic substance layer, and the redox dye layer on the base material was confirmed by visual observation, and the adhesion of these layers to the base material and the presence or absence of color unevenness were confirmed.

(2) Discoloration response The oxygen detector integrated with the oxygen scavenger prepared in each Example and each Comparative Example was placed in a vinylidene chloride-coated nylon polyethylene bag having a width of 150 mm and a length of 200 mm, sealed, and 35 ° C. In a constant temperature bath for 12 hours. Then, the change in color of the oxygen detector with the passage of time after opening was visually confirmed, the reflection spectrum was measured, and the change in peak intensity was confirmed. In addition, the ultraviolet visible spectrophotometer V-570 by JASCO Corporation was used for the measurement of a reflection spectrum.

(3) Repeatability The oxygen detector prepared in the same manner as in Example 1 was placed in a vinylidene chloride-coated nylon polyethylene bag having a width of 150 mm and a length of 200 mm in an oxygen scavenger (Powdertech Co., Ltd .: Wonderkeep (registered trademark) ) LP-100), sealed and stored in a constant temperature bath at 35 ° C. for 12 hours. Thereafter, the container was opened, and the change in color of the oxygen detector was confirmed 5 minutes, 10 minutes, and 30 minutes after opening. The oxygen detector left in the oxygen atmosphere is put in the bag again with a new oxygen absorber until the color change of the oxygen detector disappears, and the color change of the oxygen detector is confirmed in the same procedure as above. It was done repeatedly. The number of repetitions was nine.

2. Evaluation Results (1) Adhesion and Color Unevenness First, the oxygen detectors of Example 1 and Comparative Example 1 will be described. In the oxygen detector of Example 1, the binder layer contains polyvinyl alcohol and magnesium hydroxide. In the oxygen detector of Example 1, each layer could be formed with good adhesion on the surface of the polyethylene terephthalate substrate, the color of the redox dye layer was good, and no color unevenness was observed. On the other hand, in the oxygen detector of Comparative Example 1, the binder layer was formed using only an aqueous polyvinyl alcohol solution. That is, the binder layer does not contain magnesium hydroxide. In the oxygen detector of Comparative Example 1, although each layer could be formed on the surface of the polyethylene terephthalate substrate, it was difficult to form a redox dye layer or the like with a uniform thickness, or The color unevenness was observed before the deoxygenation because of insufficient adhesion.

  Comparative Example 2 contains aluminum hydroxide instead of magnesium hydroxide as the binder layer. By adding aluminum hydroxide to the binder layer, compared with Comparative Example 1, the adhesion between the basic substance layer and the redox dye layer was good, and there was little color unevenness. However, compared with the oxygen detector of Example 1 containing magnesium hydroxide in the binder layer, adhesion was low and color unevenness was also observed.

  The oxygen detectors of Example 2 and Example 3 were produced in the same manner as Example 1 except that the material of the base material was different. In any case, each layer was able to be formed on each substrate with good adhesion, so that the binder layer contains polyvinyl alcohol and magnesium hydroxide, thereby having water absorption properties such as PET film and OPP film. Even when a base material that is not used was used, it was confirmed that a printing type oxygen detector could be produced using a redox dye layer forming solution prepared in the form of a water-based ink on the base material.

  On the other hand, when Comparative Examples 2 to 4 are compared, the oxygen detector of Comparative Example 4 using the OHP film as a base material is hydroxylated in the binder layer when compared with the oxygen detectors of Comparative Examples 2 and 3. When aluminum hydroxide was added instead of magnesium, the redox dye layer was thin and formed with good adhesion. The OHP film is obtained by performing water absorption treatment on the surface of a PET film. Since the water absorption of the base material is higher than that of other base materials (PET film / OPP film), it is considered that the redox dye layer could be formed on the base material with good adhesion.

(2) Reflection spectrum FIGS. 3 and 4 show the reflection spectra measured for the oxygen detectors of Example 1 and Comparative Example 1. FIG. The oxygen detection agent of Example 1 exhibited a bluish purple color before deoxygenation, and peaks appeared at a wavelength of 588 nm and a wavelength of 663 nm. After being stored for 12 hours together with the oxygen scavenger in a sealed bag, the absorbance in the visible light region was about 0.01 as shown in FIG. 3f, and white color (binder layer color) was exhibited. On the other hand, the peak intensity at the same position before deoxygenation was about 6.0. After opening the sealed bag, the peak intensity after 5 minutes was about 1.0, which was about 15% of the peak intensity before deoxygenation. The peak intensity after 30 minutes of opening was about 3.0, which was about 50% of the peak intensity before deoxygenation. The peak intensity at the same position 1 hour after opening was about 5.0, and about 80% before deoxygenation. It was confirmed that good discoloration responsiveness could be secured since the color was developed to such an extent that it was visually recognized 5 minutes after detecting oxygen in the atmosphere.

  On the other hand, the oxygen detector of Comparative Example 1 exhibited a blue color before deoxygenation, and peaks appeared at positions of a wavelength of 610 nm and a wavelength of 664 nm. After being stored in the sealed bag together with the oxygen scavenger for 12 hours, the absorbance in the visible light region was about 0.01 as shown in FIG. 3f, and the color was colorless (see FIG. 4f). On the other hand, the peak intensity at the same position before deoxygenation was about 8.0. After opening the sealing bag, the peak intensity after 5 minutes is about 0.07, the peak intensity after 30 minutes of opening is about 0.3, and the peak intensity at the same position 1 hour after opening is about 0.00. 6. Even after 1 hour has passed since it was placed in an oxygen atmosphere, it showed only a peak intensity of 10% or less before deoxygenation, and it was confirmed that the color change responsiveness was lower than that of the oxygen detector of Example 1.

  Next, in FIG. 5, the reflection spectrum measured about the oxygen detection agent of the comparative example 2 is shown. The oxygen detection agent of Comparative Example 2 exhibited a blue color before deoxygenation, and peaks appeared at positions of a wavelength of 606 nm and a wavelength of 666 nm. After being stored for 12 hours together with the oxygen scavenger in a sealed bag, the absorbance in the visible light region was about 0.01 as shown in FIG. 5f, and white color (binder layer color) was exhibited. On the other hand, the peak intensity at the same position before deoxygenation was about 9.0. After opening the sealed bag, the peak intensity after 5 minutes was about 1.0, which was about 15% of the peak intensity before deoxygenation. Further, the peak intensity after 30 minutes of opening was about 2.0, which was about 22% of the peak intensity before deoxygenation. Although the discoloration response of the oxygen detector of Comparative Example 2 is improved as compared with Comparative Example 1, the discoloration response is lower than that of Example 1, and the oxidation-reduction reaction of the redox dye is rapidly performed. Therefore, it is considered that sufficient conditions (water retention amount, pH, etc.) are insufficient.

  In addition, the reflection spectrum shown in FIGS. 3-5 has a peak in two wavelength positions as above-mentioned. The peak on the long wavelength side is a peak of the methylene blue monomer, and appears at approximately 663 nm to 666 nm. On the other hand, the short wavelength side peak shows a dimer peak of methylene blue, and the peak position is confirmed to shift to the short wavelength side as the concentration of methylene blue increases, that is, the peak intensity increases. . When the concentration of methylene blue is increased, aggregates such as trimers and tetramers are likely to be formed. Therefore, it is considered that a peak position shift is observed.

  In preparing the binder layer forming solution, in place of magnesium hydroxide, using calcium hydroxide, magnesium oxide, sodium hydroxide, potassium hydroxide, etc., production of an oxygen detector in the same manner as in Example 1. Tried. However, when calcium hydroxide, sodium hydroxide, or potassium hydroxide is used, the browning reaction of D-glucose used as a reducing agent occurs, the redox dye layer exhibits a brown color, and the redox dye is reduced. It was difficult to maintain. Therefore, it has been difficult to obtain a practical oxygen detector. In addition, when magnesium oxide was used, when magnesium oxide was added to the polyvinyl alcohol aqueous solution, the binder layer forming solution gelled immediately, and it was difficult to apply the binder 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 polyvinyl alcohol, the binder layer forming solution does not immediately gel, and the binder layer forming solution is applied thinly on the substrate. It was possible to secure sufficient workability. In addition, the binder layer solidifies faster than when only the polyvinyl alcohol is used when drying the binder layer forming solution. From this, it is likely that the addition of magnesium hydroxide to the binder layer will increase the cross-linking density of the polyvinyl alcohol and ensure sufficient water retention to allow the redox reaction of the redox dye to be performed well. However, it is considered that the base material, the basic substance layer, and the redox dye layer are functioned as an adhesive layer for bringing them into close contact with each other.

  Further, when the oxygen detection layer is formed on the base material via the binder layer, the basic substance layer is formed on the binder layer as described in the above embodiment and this example, and then the basicity layer is formed. By forming the oxidation-reduction dye layer on the material layer, an oxygen detector having good color change responsiveness and color development could be obtained. In contrast, when a single oxygen detection layer containing all of the basic substance, the reducing agent, and the redox dye is formed on the binder layer, the color change response is compared to the case where the oxygen detection layer has a two-layer structure. In terms of color and color development, it was insufficient. This is considered to be one of the causes that the browning reaction of the reducing saccharide occurs when the reducing agent (D-glucose) is included in the basic substance layer, and the color change responsiveness and color development decrease. On the other hand, as described in the above embodiment and this example, the basic substance layer is a layer containing only a basic substance, and a redox dye layer containing a reducing agent is formed on the basic substance layer. Thus, it was possible to suppress the browning reaction of the reducing agent (D-glucose), and to obtain an oxygen detector having good color change responsiveness and good color development.

  Furthermore, the OHP film was better than the PET film and the OPP film from the viewpoint that the basic substance layer and the redox dye layer can be formed on the substrate with good adhesion. However, it was confirmed that it is most preferable to use a PET film as the substrate from the viewpoint that a clearer color tone change and quick color change responsiveness can be obtained.

(3) Repeatability When the color change of the oxygen detection agent of Example 1 was repeatedly confirmed 9 times, as shown in FIG. 6, the oxygen detection agent of Example 1 was kept at a constant temperature for 12 hours as shown in FIG. After storage, it was confirmed that the oxygen detector exhibited a white color and methylene blue had a reduced structure. In addition, when the oxygen detecting agent is placed in an oxygen atmosphere after opening the ninth time, the oxygen detecting agent becomes darker in blue with time, and the coloration after 30 minutes is about the same as the first time. Became. From this, it was found that the oxygen detector of Example 1 can detect the presence or absence of oxygen in the atmosphere without deteriorating even when used repeatedly a plurality of times.

  According to the present invention, it is possible to provide an oxygen detector having good adhesion even on the surface of a hydrophobic substrate and a method for producing the oxygen detector while ensuring a clear color tone change and good discoloration response. Can do.

Claims (7)

On the substrate
A binder layer containing magnesium hydroxide and a binder;
An oxygen detection layer containing a redox dye that changes color tone depending on the presence or absence of oxygen in the atmosphere;
Are stacked in the order from the base material side. The oxygen sensing layer is
A basic substance layer containing a basic substance;
A redox dye layer comprising a reducing agent and the redox dye;
The oxygen detector according to claim 1, wherein the oxygen detector has a two-layer structure in which the binder layer is laminated in this order from the base material side.   The oxygen detector according to claim 1, wherein the base material is a transparent resin base material.   The oxygen detection agent according to any one of claims 1 to 3, wherein the binder is polyvinyl alcohol.   The oxygen detection agent according to any one of claims 1 to 4, wherein the basic substance is sodium carbonate.   The oxygen reducing agent according to any one of claims 1 to 5, wherein the reducing saccharide is a monosaccharide. A method for producing an oxygen detector capable of detecting the presence or absence of oxygen in an atmosphere by a change in color tone of a redox dye,
Forming a binder layer containing magnesium hydroxide and a binder on the substrate;
On the binder layer, a step of forming an oxygen detection layer containing a redox dye that changes the color tone depending on the presence or absence of oxygen in the atmosphere;
A method for producing an oxygen detector, comprising: