JP4831293B2 - Oxygen indicator and packaging material using the same - Google Patents

Description

  The present invention relates to an oxygen indicator and a packaging material using the oxygen indicator, and more particularly, an oxygen indicator for determining the deoxygenation state in the presence of oxygen, for example, deoxygenation packaging of foods and pharmaceuticals with an oxygen absorbent. It is related to the packaging material.

  Oxygen is known to oxidize food and pharmaceutical cosmetics due to its high reactivity and cause deterioration. Many foods and pharmaceutical cosmetics prevent deterioration by encapsulating an oxygen scavenger in the package to maintain the freshness of food and the quality of pharmaceutical cosmetics. And the oxygen indicator is enclosed simultaneously for the confirmation of the capability of the enclosed oxygen scavenger, and the confirmation of oxygen intrusion due to the sealing failure of the packaging material, damage during handling operations such as pinholes and transportation.

  Conventionally, oxygen indicators using redox dyes that reversibly change color by redox have been proposed, and several types of oxygen indicators with different combinations of redox dyes, reducing agents, binders, etc. have been put on the market. These oxygen indicators are based on the property that the redox indicator exhibits a different color tone between the reduced type and the oxidized type, and methylene blue, which is generally used, is reduced by the action of the reducing agent in the absence of oxygen. That is, it is colorless and is oxidized by oxygen under aerobic conditions to exhibit a blue color (see, for example, Patent Document 1).

  An oxygen indicator has also been developed that can easily confirm discoloration by mixing two or more types of pigments (see, for example, Patent Document 2).

  In fact, the composition of oxygen detectors has been studied and oxygen indicators with light resistance are being developed. Also, since the oxygen indicator is usually provided at a position where it can be seen from the outside of the packaging material, the oxygen indicator is more likely to be deteriorated by light when the content is distributed for a long time. In addition, an oxygen indicator in which a layered silicate selected from the smectite group is mixed with an oxygen detection composition has been developed as a highly light-resistant indicator (see, for example, Patent Document 3).

JP 56-84772 A JP-A-5-209871 JP 2004-45365 A

  Although several types of oxygen indicators using the oxidation-reduction type dye as described above have been put on the market, there is a drawback that a sufficient indicator function is not exhibited due to fading and decomposition caused by light irradiation. In particular, when an indicator layer is provided by applying processing such as printing or coating to a substrate such as paper or plastic film, the indicator layer becomes a thin film.

  Moreover, in the oxygen indicator regarding patent document 3, this oxygen indicator has the fault that it takes comparatively time before exhibiting an oxygen detection function.

  The present invention has been made to solve the above-described problems of the conventional oxygen indicator, and is a highly light-resistant oxygen indicator that does not deteriorate even under long-time light irradiation, and is a plastic film or paper. It is possible to provide an indicator layer on a substrate such as by printing, coating, etc., and an object of the present invention is to provide an oxygen indicator in which light resistance does not decrease.

The present invention has been made to solve the above-described problems of the prior art. The invention of claim 1 comprises a substrate, a first oxygen indicator layer and the second oxygen indicator layer from the substrate side becomes disposed in this order, a layered silicate, wherein the first oxygen indicator layer is selected from the smectite group salt, an oxygen detecting agent composition comprising a redox dye and a reducing agent, to an oxygen indicator, wherein the second oxygen indicator layer is an oxygen detecting agent composition comprising a redox dye and a reducing agent .

Further, an invention according to claim 2, wherein, in said second oxygen indicator layer surface of the oxygen indicator according to claim 1, Ri name is laminated a layer containing a redox dye and, oxygen indicator according to claim 1 between the substrate and the first oxygen indicator layer, it relates to an oxygen indicator layer containing a reducing agent, characterized in Rukoto such are stacked.

A fourth aspect of the present invention relates to the oxygen indicator according to any one of the first to third aspects, wherein the second oxygen indicator layer contains a dye that does not change color by oxidation-reduction .

According to a fifth aspect of the present invention , there is provided an oxygen permeable resin layer comprising a thermoadhesive resin on the second oxygen indicator layer of the oxygen indicator according to any one of the first to fourth aspects or a layer surface containing a redox dye. It is related with the packaging material with an oxygen indicator characterized by being laminated | stacked .

  By adopting the configuration of the present invention, the first oxygen indicator layer including the oxygen detector composition obtained by mixing a layered silicate selected from the smectite group, a redox dye, and a reducing agent has light resistance. On the other hand, since the second oxygen indicator layer has a high reaction speed for exhibiting an oxygen detection function, it has light resistance and can provide an oxygen indicator with a high reaction speed for exhibiting an oxygen detection function.

  Further, a layer containing a redox dye is laminated on the second oxygen indicator layer, and a layer containing at least a reducing agent, a first oxygen indicator layer, and a second indicator layer are laminated in this order on the substrate. Accordingly, the second oxygen indicator layer can contain a dye that does not change color due to oxidation and reduction, and the color change as an oxygen indicator can be clarified.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Explanation of FIG. 1]
FIG. 1 is a cross-sectional view of one embodiment of the oxygen indicator of the present invention. The oxygen indicator of the present invention comprises an oxygen detector composition obtained by mixing a redox pigment, a reducing agent and a layered silicate selected from the smectite group on the substrate layer (1) as shown in FIG. A second oxygen indicator layer (4) comprising an oxygen detector composition comprising a first oxygen indicator layer (3) comprising an anchor coat layer (2) and further comprising at least a redox dye and a reducing agent mixed. The oxygen permeable resin layer (7) is laminated by the dry lamination method through the overcoat layer (5) and the adhesive layer (6).

Hereinafter, each layer will be described in detail.
[Base material layer]
Since the base material layer (1) has an oxygen gas barrier property and the discoloration of the oxygen indicator layer must be visually confirmed from the base material side, a resin film having transparency is used. For example, polyethylene terephthalate (hereinafter referred to as polyethylene terephthalate) "PET"), nylon, polypropylene, and films thereof coated with a substance having an oxygen gas barrier property, such as polyvinylidene chloride, or a film coextruded with ethylene vinyl alcohol copolymer resin or the like, or And a film on which a metal oxide such as silicon oxide is deposited. Synthetic paper can also be used.

[Anchor coat layer]
The anchor coat layer (2) is preferably formed on the base material layer (1) in order to improve the adhesion of the first oxygen indicator layer (3). As anchor coats that can be used, polyester polyurethane, vinyl chloride / vinyl acetate copolymer, chlorinated polypropylene, chlorinated ethylene / vinyl acetate copolymer, etc. can be used. Need to be used. The anchor coat layer (2) is provided by a printing method such as gravure printing or a coating method.

[First oxygen indicator layer]
The first oxygen indicator layer (3) is composed of an oxygen indicator ink containing an oxygen detector composition obtained by mixing a redox dye and a reducing agent and a layered silicate selected from the smectite group, The indicator layer is constructed by various printing methods such as offset printing, letterpress printing, screen printing, and coating methods. Next, the oxygen indicator ink will be described. As a suitable binder for converting the oxygen detector composition into an ink, for example, suitable examples include cellulose derivatives such as ethyl cellulose, ethyl hydroxyethyl cellulose, cellulose acetylpropionate, butyral resin, polyester resin, acrylic resin, One or more of a polyether resin, a polyamide resin, a petroleum resin, and the like can be given. These binders are preferably aromatics such as toluene and xylene, esters such as ethyl acetate and butyl acetate, ketones such as methyl ethyl ketone and methyl isobutyl ketone, alcohols such as methanol, ethanol and isopropyl alcohol, It is used by dissolving or dispersing in an organic solvent such as ethylene glycol monoethers or glycols such as ethylene glycol, or water. The binder is preferably used by dissolving or dispersing 5 to 100 parts by weight with respect to 100 parts by weight of the solvent. Furthermore, it is obtained by dissolving or dispersing the oxygen detector composition in a ratio of 5 to 40 parts by weight with respect to 100 parts by weight of the resin solution. As a method of dissolving or dispersing, all components may be mixed and kneaded by a general method such as a sand mill, ball mill, roll mill, attritor, etc. In order to maintain long performance as an ink, the ink must be sealed in a sealed state. It is desirable to make it. Various additives such as nonionic surfactants and auxiliaries can be added to the ink.

[Second oxygen indicator layer]
The second oxygen indicator layer (4) is composed of an oxygen indicator ink containing an oxygen detection agent composition formed by mixing at least a redox dye and a reducing agent, and, like the first oxygen indicator layer (3), gravure printing, The indicator layer is constructed by various printing methods such as offset printing, letterpress printing, screen printing, and coating methods. The oxygen indicator ink is converted into an ink by the above-described method.

  As the redox dye of the oxygen detector composition used in the first oxygen indicator layer (3) and the second oxygen indicator layer (4) of the present invention, in addition to methylene blue, new methylene blue, neutral red, indigo carmine, acid red, Safranin T, phenosafranine, capri blue, Nile blue, diphenylamine, xylene cyanol, nitrodiphenylamine, ferroin, N-phenylanthranilic acid and the like can be used.

  In addition to ascorbic acid, as a reducing agent for the oxygen detector composition, erythorbic acid and its salt, ascorbate, D-arabinose, D-erythrose, D-galactose, D-xylose, D-glucose, D -Reducing sugars such as mannose, D-fructose, D-lactose, metal salts such as stannous salts, and the like can be used.

  The type of layered silicate used in the present invention is selected from the smectite group, for example, montmorillonite, and layered silicates belonging to natural smectite groups such as beidellite, saponite, hectorite, and soconite. Examples include salt (natural smectaite). In addition, a layered silicate (synthetic smectite) belonging to the smectite group synthesized hydrothermally using an inorganic compound as a starting material can also be used. Among them, a preferred layered silicate is synthetic smectite.

  The oxygen detector composition of the present invention is a composite in which an aqueous dispersion of a layered silicate, a cationic surfactant, an organic dye, a reducing agent, and an optional basic substance are inserted between the layers of the layered silicate. Although it is preferable that it is a body, it is not necessarily limited to this. Whether or not a dye or the like is inserted between the layers of the layered silicate is determined by X-ray diffraction or discoloration based on the proximity of the dye and the reducing agent by a cationic surfactant inserted between the layers of the layered silicate. This can be confirmed by the expression of the function.

  In this invention, when forming the layer containing a reducing agent on a base material, it is desirable to laminate | stack in order of the layer containing a reducing agent, the 1st oxygen indicator layer, and the 2nd oxygen indicator layer. Further, when forming a layer containing a redox dye, the stacking order can be arbitrarily set. For example, it may be configured as a layer containing a reducing agent / a first oxygen indicator layer / a layer containing a redox dye / a second oxygen indicator layer.

[Overcoat layer]
The overcoat layer (5) is preferably formed in order to improve the adhesion between the second oxygen indicator layer (4) and the adhesive layer (6). As the overcoat that can be used, polyester polyurethane, vinyl chloride / vinyl acetate copolymer, chlorinated polypropylene, chlorinated ethylene / vinyl acetate copolymer, etc. can be used. It is necessary to select and use. The overcoat layer (5) is provided by a printing method such as gravure printing or a coating method.

[Adhesive layer]
As the adhesive to be used, any of vinyl-based, acrylic-based, polyamide-based, epoxy-based, rubber-based, urethane-based and the like can be used, but a urethane-based solvent-based adhesive is particularly preferable from the viewpoint of adhesive strength. The adhesive is applied on the base material layer (1) and the overcoat layer (5) by gravure coating, roll coating, etc., the adhesive layer (6) is provided, and the oxygen permeable resin layer (7) and dry lamination are provided. And the oxygen indicator of the present invention is formed.

(Oxygen permeable resin layer)
The oxygen permeable resin layer (7) protects the formed oxygen indicator layer and is a film having oxygen permeability, such as low density polyethylene (hereinafter referred to as “PE”), linear low density polyethylene, And ethylene / vinyl acetate copolymer, ionomer, polypropylene (hereinafter referred to as “PP”), and the like. Furthermore, by laminating the oxygen permeable resin layer (7) with a heat-adhesive film, PE, unstretched PP, linear low density polyethylene, ethylene / vinyl acetate copolymer, ionomer, etc. The inventive oxygen indicator itself can be integrated with the packaging material. This packaging material can be formed into a bag shape by a normal technique. In this way, it is possible to save the trouble of individually putting the oxygen indicator into the package.

  Next, a method for laminating each layer will be described. First, an anchor coat layer (2) is provided on the base material layer (1) by a printing method such as gravure printing or a coating method, and further, a first oxygen indicator layer (3), a second indicator layer (4), and an overcoat layer (5) is provided in order by a printing method or a coating method. Next, the oxygen permeable resin layer (7) is formed through the adhesive layer (6), and may be carried out by a conventionally known dry lamination method. Moreover, there is no problem even if pasting is performed by a solvent-free lamination method using a solvent-free adhesive, and it may be appropriately selected depending on the required performance of the product.

  Next, the present invention will be described in more detail with reference to examples and comparative examples.

First oxygen indicator ink: synthetic smectite (trade name: Smecton SA, manufactured by Kunimine Kogyo Co., Ltd., hereinafter abbreviated as “smectite”), 20 ml of 0.5 g / l aqueous dispersion, methylene blue 01 g, 5 g of an aqueous solution in which 1.0 g of D-(+)-glucose and 0.36 g of cetyltrimethylammonium bromide are dissolved, 0.1 N sodium hydroxide is added dropwise to adjust the pH to 11.0, and the binder 51 g of resin, 7.5 g of glycerin, 0.6 g of synthetic silica, 0.8 g of acid red, 87 g of water and 42 g of propanol were added and finely dispersed using a paint conditioner to prepare an oxygen detection ink composition.
Second oxygen indicator ink: 5 g of aqueous solution in which 0.01 g of methylene blue, 1.0 g of D-(+)-glucose and 0.36 g of cetyltrimethylammonium bromide are dissolved, 0.1N sodium hydroxide is added dropwise. To pH 11.0, add 51 g of binder resin, 7.5 g of glycerin, 0.6 g of synthetic silica, 0.8 g of acid red, 87 g of water and 42 g of propanol, and finely disperse using a paint conditioner. A detection ink composition was prepared.
Anchor coat: Urethane resin, diluent solvent Overcoat: Urethane resin, diluent solvent

  After the anchor coat (2) having the above composition is printed on the PET film (1) on which the metal oxide is vapor-deposited and dried, the first oxygen indicator ink and the second oxygen indicator ink prepared with the above ink composition are separated. And printing continuously. After drying again to form the first oxygen indicator layer and the second oxygen indicator layer, the overcoat (5) is printed and dried, and a two-component curable urethane-based adhesive (6) is used on the surface. Dry laminate the oxygen permeable PE film (7). (Laminated structure: PET with metal oxide deposited / anchor coat / first oxygen indicator layer / second oxygen indicator layer / overprint layer / adhesive / PE)

[Comparative Example 1]
After the anchor coat (2) having the above composition is printed and dried on the PET film (1) on which the metal oxide is deposited, the first oxygen indicator ink prepared with the above ink composition is printed and dried to obtain the first oxygen After the indicator layer (3) is formed, the above overcoat (5) is printed and dried, and an oxygen permeable PE film (7) using a two-component curable urethane adhesive (6) on the surface. Dry lamination. (Laminated structure: PET with metal oxide deposited thereon / anchor coat / first oxygen indicator layer / overprint layer / adhesive / PE)

[Comparative Example 2]
After the anchor coat (2) having the above composition is printed and dried on the PET film (1) on which the metal oxide is deposited, the second oxygen indicator ink prepared with the above ink composition is printed and dried to obtain the second oxygen. After the indicator layer (4) is formed, the above overcoat (5) is printed and dried, and an oxygen permeable PE film (7) using a two-component curable urethane adhesive (6) on the surface. Dry lamination. (Lamination structure: PET / anchor coat / second oxygen indicator layer / overprint layer / adhesive / PE deposited with metal oxide).

[Experiment 1]
After manufacturing the above oxygen indicator, the adhesive is cured in an atmosphere at 25 ° C., and then encapsulated with a deoxidizer in a packaging material made of PET / PE on which a metal oxide is vapor-deposited to make an oxygen-free state. The container was opened and brought into an aerobic state, and the color change was observed. Table 1 shows the results. The oxygen-free color indicates the color tone when about 0.5 days have passed after each adhesive is cured under the above-mentioned conditions under deoxidation (at 25 ° C. atmosphere). The aerobic color indicates a color tone when the packaging material is opened and left in the atmosphere (at 25 ° C. atmosphere) for one day.

[Experiment 2]
After producing the above oxygen indicator, the adhesive is cured in an atmosphere at 25 ° C., and then sealed with a deoxidant in a PET / PE packaging material on which a metal oxide is deposited, and 10000 lux fluorescent lamp in the absence of oxygen. Were irradiated for 5 consecutive days. Thereafter, the color tone in the absence of oxygen was observed. Then, the packaging material was opened and the color tone when 3 days passed was observed. The results are shown in Table 2.

  From the results of Experiment 1, Comparative Example 2 and Example are pink, indicating that the oxygen detection function is exhibited. On the other hand, Comparative Example 1 exhibits a reddish purple color and indicates that the oxygen detection function is not sufficiently exhibited. That is, the second oxygen indicator layer has a faster reaction speed for oxygen detection than the first oxygen indicator layer.

  From the results of Experiment 2, Comparative Example 1 and Example changed color to blue in the aerobic state, but Comparative Example 2 did not change color and did not show aerobic color. That is, it was shown that the first oxygen indicator layer has light resistance than the second oxygen indicator layer. Therefore, by stacking the first oxygen indicator layer with light resistance and the second oxygen indicator layer with fast reaction speed to detect oxygen, it is possible to make an oxygen indicator with light resistance and fast reaction speed to detect oxygen. became.

  In the above embodiment, the oxygen indicator printed on the PET film vapor-deposited with the metal oxide has been described. However, the present invention is not limited to this, so long as the selection of the anchor coat or the binder of the oxygen indicator ink is considered. It can also be applied to biaxially oriented polypropylene (OPP), nylon, and the like. And when it is set as the packaging material with an oxygen indicator, what is necessary is just to make the layer which has a certain amount of oxygen barrier property into a base material layer. Alternatively, a layer having a certain degree of oxygen barrier property may be provided on the surface of the base material layer, and laminated as an oxygen barrier property layer / base material layer / oxygen indicator layer / oxygen permeable resin layer.

  The use of the oxygen indicator of the present invention and the packaging material using the oxygen indicator is mainly deoxygenation packaging for foods, pharmaceuticals and cosmetics, but it can be used for deoxygenation packaging in other fields, and there is no particular limitation. In addition, the deoxygenation packaging is not particularly limited by a technique such as gas replacement with an inert gas such as an oxygen absorbent or nitrogen.

1 shows one form of an oxygen indicator according to the present invention.

Explanation of symbols

1: Base material layer 2: Anchor coat layer 3: First oxygen indicator layer 4: Second oxygen indicator layer 5: Overcoat layer 6: Adhesive layer 7: Oxygen permeable resin layer

Claims (4)

  A base material, a first oxygen indicator layer and a second oxygen indicator layer are provided in this order from the base material side, and the first oxygen indicator layer is a layered silicate, redox dye and reduction selected from the smectite group An oxygen indicator comprising an oxygen detector, wherein the second oxygen indicator layer is an oxygen detector composition containing a redox dye and a reducing agent. In the second oxygen indicator layer surface of the oxygen indicator according to claim 1, Ri Na with a layer containing a redox dye are laminated, and the substrate and the first oxygen indicator layer of an oxygen indicator according to claim 1 An oxygen indicator , wherein a layer containing a reducing agent is laminated between the two . Oxygen indicator according to any one of claims 1 to 2, characterized in that the second oxygen indicator layer contains a dye that does not discolor by oxidation-reduction. An oxygen-permeable resin layer made of a heat-adhesive resin is laminated on the second oxygen indicator layer of the oxygen indicator according to any one of claims 1 to 3 or a layer surface containing a redox dye. Packaging material with oxygen indicator.

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