JP6805744B2 - Oxygen indicator - Google Patents

Description

The present invention relates to an oxygen indicator used to visually detect that a deoxidized state is maintained for long-term storage of the contents in a packaging bag.

Conventionally, there are many oxygen indicators that make it easy to check the oxygen exposure status when the deoxidized state in the packaging container containing the oxygen scavenger changes due to pinholes, defective seals, defective oxygen scavengers, etc. It is on the market. The oxygen indicator utilizes the property that the redox indicator exhibits different color tones between the reduced form and the oxidized form.

The oxygen indicator shows that when there is sufficient oxygen in the ambient atmosphere, oxygen suppresses the action of the reducing agent and the redox indicator takes an oxidized structure, but oxygen is present in the ambient atmosphere due to the action of the oxygen scavenger and the like. When it does not work, the reducing agent works and the redox indicator has a reduced structure. Utilizing the change in color tone at this time, the oxygen indicator using the oxygen reduction indicator visually confirms the color tone and determines whether it corresponds to either the reduced state (reduced color) or the oxidized state (oxidized color). ing.

In an oxygen indicator using such an oxygen reduction indicator, for example, oxygen is provided by changing the thickness of the oxygen indicator layer depending on the part, and the degree of change in the color tone of the oxygen indicator is different between the parts having different thicknesses. The leakage observation time can be adjusted so that changes can be confirmed over time (Patent Document 1), and the oxygen gas barrier layer is laminated on the oxygen indicator layer with different thickness for each part to allow oxygen permeation. Is changed for each part so that the change over time in the amount of oxygen can be visually confirmed (Patent Document 2) and the like.

However, when the thickness of the oxygen gas barrier layer is changed depending on the part, when the oxygen gas barrier layer is laminated by printing, a part of the dye component is transferred from the oxygen indicator layer and the barrier performance is lowered, so that an appropriate barrier performance can be obtained. The oxygen gas barrier layer required a film thickness of more than 0.5 μm. On the other hand, an inorganic layered compound is often added to the oxygen gas barrier layer, but in that case, there is a problem that the delamination strength decreases as the film thickness increases.

Japanese Unexamined Patent Publication No. 2007-183125 JP-A-2016-173345

The present invention has been made in view of the above circumstances. By providing an oil-based ink layer of urethane resin between the oxygen indicator layer and the oxygen gas barrier layer, a thin film has sufficient gas barrier properties, and delamination is performed. It is an object of the present invention to provide an oxygen indicator capable of visually confirming a change in the amount of oxygen over time without reducing the intensity.

In order to solve the above problems, the invention according to claim 1 of the present invention is
Possess oxygen sensing function on a substrate, a hydrophilic oxygen indicator layer and the oil-based ink layer and a hydrophilic oxygen gas barrier layer of are sequentially laminated, wherein the oxygen gas barrier layer covers the oil-based ink layer partially It is an oxygen indicator characterized by this.

The invention according to claim 2 of the present invention is the oxygen indicator according to claim 1, wherein the oxygen gas barrier layer has a film thickness of 0.3 μm to 0.5 μm.

The invention according to claim 3 of the present invention is the oxygen indicator according to claim 1 or 2, wherein the oil-based ink layer contains a urethane-based resin.

The invention according to claim 4 of the present invention is the oxygen indicator according to any one of claims 1 to 3, wherein the oxygen gas barrier layer contains a polyvinyl alcohol resin and an inorganic layered compound.

The invention according to claim 5 of the present invention is the oxygen indicator according to any one of claims 1 to 4, wherein the oxygen indicator layer contains a polyvinyl acetal resin and a redox dye.

According to the invention according to claim 1 of the present invention, by providing the oil-based ink layer on the oxygen indicator layer, the transfer of the dye component between the hydrophilic oxygen indicator layer and the oxygen gas barrier layer is eliminated, so that oxygen is eliminated. Sufficient oxygen gas barrier property can be obtained even if the barrier property of the gas barrier layer is not deteriorated and the oxygen gas barrier layer is made thin so that delamination does not easily occur. Also, by partially providing the oxygen gas barrier layer on the oil-based ink layer, The degree of oxygen gas permeation over time can be changed between the part with and without the oxygen gas barrier layer, and the amount of residual oxygen in the surrounding atmosphere can be visually estimated from the difference in the color tone of the resulting oxygen indicator. It can be carried out.

According to the invention of claim 2, when the thickness of the oxygen gas barrier layer is 0.3 μm to 0.5 μm, oxygen permeability of 3 to 5 cc / m ² · day can be obtained, so that the oxygen gas barrier layer can be obtained. The difference in color tone between the portion provided with and the portion not provided is obtained within 24 hours, which is practically suitable, and can be visually confirmed as a clear difference in color tone.

According to the invention of claim 3, since the oil-based ink layer contains a urethane-based resin, it has excellent adhesion and does not inhibit the coloration of the redox indicator in the oxygen indicator layer underneath. In addition, it is easy to prevent the transfer of components from the oxygen indicator layer to the oxygen gas barrier layer.

According to the invention of claim 4, the oxygen gas barrier layer is transparent and has excellent oxygen gas barrier property by containing a polyvinyl alcohol resin and an inorganic layered compound, and can be prepared as a composition for forming an oxygen gas barrier layer. Since it is excellent in coatability, it is easy to set the film thickness to 0.3 μm to 0.5 μm.

According to the invention of claim 5, the oxygen indicator layer contains a polyvinyl acetal resin and a redox dye, so that the color tone is excellently changed by the redox reaction, and the composition is for forming the oxygen indicator layer. Excellent coatability.

(A) It is sectional drawing which shows one Embodiment of the oxygen indicator of this invention. (B) It is a plan view of the oxygen indicator. It is sectional drawing which shows the other embodiment of the oxygen indicator of this invention. It is sectional drawing of the conventional oxygen indicator.

Hereinafter, embodiments of the present invention will be described in detail.

As shown in FIG. 1, the oxygen indicator 10 of the present invention is characterized in that the oxygen indicator layer 2, the oil-based ink layer 3, and the oxygen gas barrier layer 4 are sequentially formed on one surface of the base material 1. The sealant layer 5 is further laminated on the oil-based ink layer 3 and the oxygen gas barrier layer 4 as shown in FIG. 2 for use as the oxygen indicator packaging bag (bag-shaped form in which the periphery is heat-sealed) of the present invention. You may.

The base material 1 (support) used in the present invention is preferably one that does not react with the oxygen indicator layer forming ink composition (hereinafter referred to as indicator ink) and does not inhibit the color development of the redox indicator. .. For example, a synthetic resin film can be used, and it may be a simple substance or a laminated body. Above all, in order to impart gas barrier properties to the back side of the base material (the surface opposite to the surface forming the oxygen indicator layer 2 and the like), a synthetic resin film having a thin film layer such as a metal oxide formed on the back surface is preferable.

The oxygen indicator layer 2 used in the present invention is composed of an indicator ink containing a redox indicator, a reducing agent, a polyvinyl acetal resin and a solvent, and if necessary, an additive such as a viscosity modifier or a stabilizer such as a surfactant is added. May be added.

The redox indicator is not particularly limited as long as it is a dye that exhibits different color tones in the oxidized state and the reduced state. For example, methylene blue, neumethylene blue, neutral red, indigo carmine, acid red, safranin T, phenosafranin, capri blue, nile blue, diphenylamine, xylene cyanol, nitrodiphenylamine, ferroin, N-phenylanthranilic acid and the like can be used. ..

Further, as the reducing agent, for example, reducing sugars such as ascorbic acid, ascorbate, and D-fructose can be used.

Since the oxygen indicator layer 2 according to the present invention is formed on the base material 1 (support) with a uniform film thickness, it is required that the indicator ink is fixed to the base material 1. Examples of those satisfying such requirements include butyral resin, acetal resin, polyvinyl alcohol resin, polyvinyl acetal resin and the like, and among them, polyvinyl acetal resin having both hydrophilicity and water resistance is preferable.

Examples of the solvent used for dissolving or dispersing the resin and the redox indicator to form an ink include water-based solvents such as water, methyl alcohol, ethyl alcohol, and isopropyl alcohol. These solvents may be used alone or in admixture of a plurality of solvents.

The oil-based ink layer 3 used in the present invention is composed of an oil-based ink containing an extender pigment, a urethane-based synthetic resin, and a solvent, and additives such as a curing agent may be added if necessary.

As the extender pigment, an inorganic white pigment such as calcium carbonate, barium sulfate, or aluminum hydroxide can be used.

Examples of the solvent include organic solvents such as toluene, xylene, methyl ethyl ketone and ethyl acetate. These solvents may be used alone or in admixture of a plurality of solvents.

Since the oxygen gas barrier layer 4 according to the present invention is formed on the oxygen indicator layer 2 in addition to the excellent oxygen gas barrier property, the oxygen indicator layer 2 has transparency that does not hinder the coloration of the redox indicator. Required. Examples of those satisfying such requirements include polyvinyl alcohol resins and ethylene-vinyl alcohol copolymer resins. Among them, polyvinyl alcohol resins having excellent transparency, solubility and the like are preferable.

Further, by adding the inorganic layered compound to the oxygen gas barrier layer 4, the effect of further improving the oxygen gas barrier property in addition to the oxygen gas barrier property of the resin can be obtained. Specifically, by adding an inorganic layered mineral, it is possible to prevent the oxygen gas barrier from being lowered under high humidity.

The inorganic layered compound is preferably one that swells in a solvent, and mainly includes smectites, vermiculites, and mica. Specifically, kaolinite, antigolite, montmorillonite, synthetic mica and the like can be used. Further, scaly silica or the like can be used. These may be used alone or in combination of two or more. Of these, synthetic mica is preferable because of its gas barrier performance and coating process suitability.

The oxygen indicator layer 2, the oil-based ink layer 3, and the oxygen gas barrier layer 4 can be suitably formed by various printing methods such as known gravure printing, screen printing, and flexographic printing.

When the oxygen indicator 10 configured as described above is first placed in a deoxidizing environment (for example, a bag containing an oxygen scavenger), the color tone of the oxygen indicator layer 2 is the same for both the part with and without the oxygen gas barrier layer. It exhibits color and has a uniform color tone. After that, when placed in an aerobic environment (for example, when the air leaks into the above bag), the oxygen indicator layer 2 gradually changes its color to an oxidized color due to the action of oxygen. At this time, the oxygen gas barrier The portion A1 not covered by the layer 4 discolors faster, and the portion A2 covered by the oxygen gas barrier layer discolors relatively slowly.

As a result, a difference in color tone appears between the portions A1 and A2, and the amount of leaked oxygen and the time can be estimated by appropriately setting the characteristics of the oxygen gas barrier layer 4. Further, in FIG. 1, the shapes of A1 and A2 are simple rectangles, but this shape is not particularly limited to a rectangle, and for example, one of them can be the shape of a character or a symbol, and then the color tone. It is also possible to make letters and symbols emerge by changing. As a result, it is possible to display that oxygen leakage is occurring in a more understandable manner.

When the periphery of the oxygen indicator of the present invention is heat-sealed and used as a package, it is necessary to laminate a heat-sealing sealant layer 5 on the entire upper surface of the oil-based ink layer 3 and the oxygen gas barrier layer 4. The resin used for the sealant layer 5 in this case is not particularly limited as long as it is a heat-meltable resin. For example, polyolefin resins such as polyethylene resin and polypropylene resin can be mentioned.

As described in detail above, according to the present invention, the interlayer strength of the oxygen gas barrier layer is maintained. Therefore, when the contents and the oxygen scavenger are enclosed in the package and stored for a long period of time, delamination or the like may occur. It is possible to obtain an oxygen indicator that can easily and clearly visually detect that the deoxidized state by the oxygen scavenger is maintained without being destroyed on the way.

Hereinafter, examples of the present invention will be specifically described with reference to FIG. 1, but the present invention is not limited thereto.

<Example 1>
[Ink for indicator]
1.5 parts of methylene blue,
Ascorbic acid 4.7 parts,
22.5 parts of water,
43.6 parts of alcohol,
Binder resin 26.1 parts,
Glycerin 1.4 parts,
0.4 parts of synthetic silica The indicator ink of the above composition is applied to the base material 1 of a polyethylene terephthalate (PET) film having a thickness of 12 μm on the back surface side by a gravure printing method, and dried to dry an oxygen indicator layer. 2 was formed so as to have a film thickness of 0.8 μm.

Next, an oil-based ink having the following composition was applied onto the oxygen indicator layer 2 obtained above by a gravure printing method and dried to form an oil-based ink layer 3 having a film thickness of 0.3 μm.

[Oil-based ink]
25.5 parts of extender pigment,
Urethane synthetic resin 15.0 parts,
Solvent 59.0 parts,
0.5 part of silica

Next, an oxygen gas barrier layer ink having the following composition was applied onto the oil-based ink layer 3 obtained above by a gravure printing method, and dried to form an oxygen gas barrier layer 4 to prepare an oxygen indicator.
The oxygen gas barrier layer 4 was provided in the region A2 partially covering the oil-based ink layer 3 as shown in FIG. 1, and was formed so as to have a film thickness of 0.3 μm after drying. The oil-based ink layer 3 is the uppermost layer in the region A1.

[Oxygen gas barrier ink]
Polyvinyl alcohol resin 3.5 parts,
Synthetic mica 18.8 parts,
Barrier urethane resin 13.4 parts,
63.2 parts of water,
IPA 11.1 copies

<Comparative example 1>
In the oxygen indicator in Example 1, the oxygen indicator as shown in FIG. 3 was produced by the same method as in Example 1 except that the oil-based ink layer 3 was not formed.

<Comparative example 2>
In the oxygen indicator in Comparative Example 1 described above, the oxygen indicator was produced by the same method as in Comparative Example 1 except that the oxygen gas barrier layer was formed so that the film thickness after drying was 0.8 μm.

(Evaluation method of oxygen indicator)
[Experiment 1]
The oxygen permeability of the prepared oxygen indicators of Examples 1 and Comparative Examples 1 and 2 was measured by the MOCON method under the conditions of a temperature of 30 ° C. and a humidity of 70% RH in accordance with JIS K7126.
Next, the adhesion strength between the oxygen indicator layer 2 and the oxygen gas barrier layer 4 was measured in accordance with JIS K7127. Table 1 shows the measurement results of oxygen permeability and adhesion strength.

[Experiment 2]
The oxygen indicators of Example 1 and Comparative Examples 1 and 2 produced were stored in a deoxidized environment to be in a deoxidized state, and then stored at room temperature and in the atmosphere to be in an aerobic state. That is, the color difference (ΔE) between the adjacent regions A1 and A2 in the deoxidized environment at the initial stage and in the aerobic state was measured with a color difference meter (X-Rite). At the same time, the color tones of the areas A1 and A2 at that time were visually compared with those in the initial stage. Table 2 shows the measurement results and the comparison judgment results of the color difference (ΔE) of the regions A1 and A2.

(Evaluation results)
As can be seen from Table 1, it was confirmed that sufficient oxygen barrier performance and adhesion strength can be obtained even if the film thickness of the oxygen gas barrier layer is thin due to the presence of the oil-based ink layer.
Next, as can be seen from Table 2, the ΔE of the region A1 8 hours after the aerobic state was set to 12, and the difference from the color tone at the initial stage could be visually confirmed. On the other hand, ΔE of region A2 was 8, and the difference from the initial stage was not clear visually (○ indicates that it could be visually confirmed, and × indicates that it could not be confirmed). Further, in the measurement result of ΔE after 12 hours, the ΔE of the region A1 is 16, the ΔE of the region A2 is 12, and the color difference between the region A1 and the region A2 can be clearly confirmed visually. I was able to do it.

From this result, it can be confirmed that according to the oxygen indicator of the present invention, oxygen is leaking visually and the degree of leakage can be easily estimated from the display of the indicator even when there is no measuring instrument. It was.

1 ... Base material 2 ... Oxygen indicator layer 3 ... Oil-based ink layer 4 ... Oxygen gas barrier layer 5 ... Sealant layer 10 ... Oxygen indicator

Claims (5)

Possess oxygen sensing function on a substrate, a hydrophilic oxygen indicator layer and the oil-based ink layer and a hydrophilic oxygen gas barrier layer of are sequentially laminated, wherein the oxygen gas barrier layer covers the oil-based ink layer partially An oxygen indicator that features that. The oxygen indicator according to claim 1, wherein the oxygen gas barrier layer has a film thickness of 0.3 μm to 0.5 μm. The oxygen indicator according to claim 1 or 2, wherein the oil-based ink layer contains a urethane-based resin. The oxygen indicator according to any one of claims 1 to 3, wherein the oxygen gas barrier layer contains a polyvinyl alcohol resin and an inorganic layered compound. The oxygen indicator according to any one of claims 1 to 4, wherein the oxygen indicator layer contains a polyvinyl acetal resin and a redox dye.

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