JP2807558B2 - Oxygen indicator label - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an oxygen indicator label, and more particularly, to an oxygen indicator label which is easy to handle and excellent in oxygen detection.

(Conventional technology and its problems) Conventionally, as a method for packaging articles easily deteriorated by oxygen, such as food, a method of vacuum packaging in a vinylidene chloride resin coated film bag having excellent gas barrier properties, or a similar bag. In addition, a method of simultaneously sealing a food or the like and an oxygen scavenger to eliminate oxygen inside has been performed.

In these packaging methods, even if the bag has excellent gas barrier properties, oxygen permeates inside for a long period of time, or oxygen enters the bag due to unexpected breakage of the bag,
There is a problem of deteriorating the packaged articles.

In such a case, as a method for determining the presence or absence of oxygen inside the bag, an oxygen indicator including a pigment that develops or changes color due to the presence of oxygen is used. The oxygen indicator is a tablet mainly composed of a pigment in a reduced state and a filler, which is enclosed in a bag, and when oxygen permeates or infiltrates into the bag, the pigment in a reduced state is oxidized. It has the effect of developing color and allowing the naked eye to detect the presence of oxygen in the bag.

However, in the case of the above-mentioned conventional tablet-type indicator, since it is difficult to fix the tablet to the inner surface of the bag or the surface of the non-packaged article, the tablet moves in the bag and becomes invisible from the outside, or the tablet collapses. There are various problems such as generation of powder and erroneous eating by infants.

As a means of solving the above problems, the present inventors have previously proposed a label type oxygen indicator.
The oxygen indicator of this label type is very easy to use and has no danger of accidental eating.However, the color developed in the gas barrier bag changes color over time, or becomes faint. There was a problem that the stability was poor and the function as an indicator was deteriorated.

Therefore, an object of the present invention is to provide an oxygen indicator which is excellent in color development stability and the like in addition to the advantages of the label type.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, in the present invention, a filler layer, an oxygen indicator layer and an overprint layer are laminated on the surface of a sheet-like substrate in the order described, and the filler layer and the overprint layer are made of a neutral to alkaline resin. It is an oxygen indicator label characterized by being formed.

(Action) By making the oxygen indicator into a label, it can be easily fixed to the inner surface of a packaging bag or the surface of a non-packaged article, oxygen detection is sensitive, external detection is easy, and accidental eating etc. Problem does not occur.

Further, by forming an oxygen indicator layer on a filler layer composed of a neutral to alkaline resin, and laminating an overprint layer composed of a neutral to alkaline resin on the surface of the oxygen indicator layer, the gas barrier property is improved. It neutralizes the acid components such as carbon dioxide in the bag and / or the acidity of the paper used as the base material, so that the developed hue is kept clear for a long time.

(Preferred Embodiment) Next, the present invention will be described in more detail with reference to preferred embodiments.

As shown in FIG. 1, the oxygen indicator label of the present invention comprises a sealing agent layer 2 composed of a neutral to alkaline resin, an oxygen indicator layer 3 and an overcoat composed of a neutral to alkaline resin on a sheet-like substrate 1. It is characterized in that the print layers 4 are laminated in the order described.

Examples of the sheet-like base material 1 used in the present invention include various types of paper such as neutral paper, alkaline paper, and acidic paper, synthetic paper, plastic film, metal foil, and composites thereof.
Any sheet-like material conventionally used in the field of printing can be used and is not particularly limited, but the present invention is useful even with acidic paper.

The filler layer 2 formed on the sheet-like substrate 1 is particularly useful when paper is used as the sheet-like substrate, and is formed from a neutral to alkaline, preferably alkaline resin.

The neutral resin used in the present invention includes the same resin as the resin used as a binder of the ink described below, while, as the alkaline resin, the neutral resin described above,
Examples include those to which an alkaline substance as described below is added. Examples of particularly preferred alkaline substances are hydroxides of alkaline earth metals such as calcium hydroxide, magnesium hydroxide and barium hydroxide. Examples of another alkaline resin include an alkali metal salt and an amine salt of a resin having a carboxyl group in a molecule such as an acrylic acid resin and a maleic acid resin, and a resin having a phenolic hydroxyl group such as a phenol resin. And cationic resins having primary to quaternary nitrogen atoms, such as polyethyleneimine, polyvinylcarbazole, polyvinylpyridine, and poly (aminoalkyl acrylate).

The formation of the filler layer is performed by adding an appropriate additive as necessary to the solution or dispersion of the neutral to alkaline resin, and adding the additive to, for example, gravure printing, offset printing, letterpress printing, screen printing, or the like. After being applied to the surface of the sheet-like substrate by a printing method or a coating method, the sheet-like substrate is formed by drying. The filler layer preferably has a thickness of about 1 to 10 g / m ² (when dried).

The oxygen indicator layer formed on the filler layer,
Formed from oxygen indicator ink. One example of the oxygen indicator ink contains a dye that changes color by oxidation and reduction.

The dye used in the indicator ink has an oxidation state
Any known dye may be used as long as it changes color (coloration or decoloration) in a reduced state, but a preferred dye is a dye which is colored in an oxidized state and which is colorless or pale in a reduced state. Examples include the following dyes.

(1) As basic structure A thiazine dye having the following formula: for example, methylene blue, etc. (2) As a basic structure Indigo dyes having the following formula: for example, potassium indigo sulfonate, etc. (3) As a basic structure (4) as a basic structure (R represents -H, an alkyl group, an allyl group); for example, CI sulfur blue 7 and the like, and a particularly preferred dye is the thiazine dye of the above (1).
The dyes as described above can be used in an oxidized state or a reduced state.

The above dye can be used alone as long as it is in a reduced state, but it is preferable to use a reducing agent in combination in order to increase the stability of the label at the time of stock.

Further, the dye can be used in an oxidized state, and in this case, it is essential to use a reducing agent in combination. That is, in this case, in the label state, the color is developed due to the presence of oxygen in the air, but when this is sealed in a bag together with the oxygen scavenger, the reducing agent used in combination acts to reduce the pigment and discolor. , Is kept in this state. Then, when oxygen enters the bag, the pigment is oxidized again and changes color.

Any reducing agent that can be used in combination with the above dye can be used as long as it can maintain the dye in a reduced state.In the case of a strong reducing agent such as hydrosulfite, the reducing agent can reduce the dye. In some cases, the dye may not be able to develop color due to overreduction, and when the label is stored, the reducing agent itself is oxidized by oxygen in the air. You have to choose.

From such a point of view, at room temperature, the reducing property of the dye is low,
A reducing agent that is not easily oxidized by oxygen in air at room temperature is preferable.

Preferred as such a weak reducing agent are reducing saccharides. Examples of such reducing saccharides include D-maltose and D-maltose.
-Glucose, D-fructose, D-esthrose,
Monosaccharides such as D-arabinose; reducing oligosaccharides comprising a glycosidic bond of a monosaccharide molecule such as maltose and lactose; and fatty acids having a hydroxyl group such as ascorbic acid can also be used. The amount used is preferably 1 to 100 parts by weight per 1 part by weight of the dye.

Further, it is preferable that an appropriate alkaline substance coexist in the indicator ink, and any such alkaline substance can be used as long as it comes to pH 8 or more upon contact with water, for example, sodium hydroxide, water Potassium oxide, sodium carbonate, potassium carbonate, calcium hydroxide, calcium carbonate, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, magnesium hydroxide, sodium acetate, potassium acetate, potassium sodium tartrate, potassium 2-ethylhexylate Hydroxides, carboxylate salts, various salts and the like. Magnesium hydroxide is particularly preferred from the viewpoint of long-term stability. The amount is preferably 1 to 500 parts by weight per 1 part by weight of the dye.

Examples of suitable binders for converting the above dyes and the like into inks include, as preferred examples, ethyl cellulose, ethyl hydroxyethyl cellulose, cellulose derivatives such as cellulose acetyllopionate, butyral resin,
Polyester resin, acrylic resin, polyether resin,
One or more of polyamide resin, petroleum resin and the like can be mentioned.

These binders are preferably aromatic, such as toluene and xylene, ethyl acetate, ester such as butyl acetate, methyl ethyl ketone, ketone such as methyl isobutyl ketone, alcohol such as methanol, ethanol, isopropyl alcohol, and more. It is used after being dissolved or dispersed 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.

The ink composition for forming the oxygen indicator layer was prepared by adding the component system to 5 to 4 parts by weight of the resin solution described above.
It is obtained by dissolving or dispersing at a ratio of 0 parts by weight. As a method of dissolving or dispersing, all the components may be mixed and kneaded by a general means such as a sand mill, a ball mill, a roll mill, an attritor, etc. Is desirable.

By adding a polyhydric alcohol such as glycerin or ethyl glycol in the above ink composition in an amount of about 5% by weight based on the total amount, the discoloration or decoloration of the dye when the label comes into contact with oxygen can be obtained. It is effective in accelerating the color. In addition, various additives such as nonionic surfactants and auxiliaries can be added to the ink composition.

The ink was prepared in a two-part ink type, that is, a dye A and a reducing agent were added to a binder liquid to prepare a liquid A, while an alkaline substance was added to a binder liquid to prepare a liquid B. Can be mixed and used immediately before the formation of the oxygen indicator layer to improve the storage stability of the ink.

Further, the above-mentioned ink composition is not reduced in the composition system, and by separately adding another dye different in color from the dye for the oxygen indicator layer, not only coloring from colorless to colored but also , It can be changed from a color to a color having a different hue. As such a dye, a general pigment or dye which has been widely used as a coloring agent for a conventional printing ink or paint can be used as it is. These other dyes can be added in an amount of about 0.05 to 5% by weight based on the whole ink composition.

The indicator ink composition configured as described above, for example, gravure printing, offset printing, letterpress printing, by a printing method or coating method such as screen printing, after applying to at least one surface of the sheet substrate,
By drying, an oxygen indicator layer is formed. The oxygen indicator layer preferably has a thickness of about 1 to ²⁰ g / m ² (when dried). It is preferable to perform a plurality of times of coating or printing in the case of increasing the thickness of the indicator layer, for example, by repeating the coating or printing more than once in the case of exceeding 5 g / m ^2, per the ink well and A layer in which discoloration is clearly visible can be obtained.

Further, in the present invention, the overprint layer 4 is formed from the same neutral to alkaline resin as described above on the surface of the oxygen indicator layer for the purpose of preventing the ink layer from falling off, improving the surface properties, and improving the coloring stability.

In this case, one of the filler phase layer and the overprint layer is desirably oxygen permeable. As a simple method for obtaining oxygen permeability, a method using an appropriate granular additive can be mentioned.

The formation of the overprint layer is performed in the same manner as the formation of the indicator layer, by applying a solution or dispersion liquid of an appropriate resin, for example, by a printing method or a coating method such as gravure printing, offset printing, letterpress printing, screen printing, or the like. Is formed by applying it to the surface and drying it. The overprint layer is 1 to 10 g / m ² (when dried)
It is preferable to set the degree.

(Examples) Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, “part” or “%” is based on weight unless otherwise specified.

 A printing ink having the following composition was prepared.

A ink composition Methylene blue 0.15 parts Safranin T 0.10 parts Cellulose acetate propionate 30 parts Fructose 15 parts Ethylene glycol 10 parts Toluene 22.5 parts Isopropyl alcohol 22.5 parts B ink composition Magnesium hydroxide 40 parts Cellulose acetate propionate 25 parts Toluene 17.5 parts Isopropyl Alcohol 17.5 parts Sealant C Cyclic rubber resin 20 parts Magnesium hydroxide 60 parts Toluene 60 parts Cyclohexane 60 parts Overprinting agent D Cyclic rubber resin 20 parts Sodium carbonate 3 parts Toluene 40 parts Cyclohexane 40 parts Example 1 Sanyo Using a gravure printing machine, on a sterilized paper (DPS, 60 g / m ² ) manufactured by Kokusaku Pulp Co., Ltd., using a gravure printing machine, a mixed ink of an ink A and an ink B (indicator ink, mixed immediately before printing) and Overprinting agent D was added in this order. It was applied and dried at a solid content of 2 g / m ² , 5.0 g / m ² and 1 g / m ² , cut into a predetermined size, and the oxygen indicator label of the present invention was obtained. The indicator layer was formed by printing twice.

When the above label is sealed in a vinylidene chloride-coated bag containing a deoxidizer (Ageless Z-200) manufactured by Mitsubishi Gas Chemical Company, the indicator layer changes from blue-violet to vivid red, This red color did not change even after one week.

Example 2 The following filler E was used in place of the filler C in Example 1.
Was used, and the oxygen indicator label of the present invention was obtained in the same manner as in Example 1 except for the above.

Sealant E 20 parts of acrylic resin containing 2 mol% of sodium acrylate 40 parts of calcium carbonate 40 parts of toluene 40 parts of cyclohexane 40 parts of vinylidene chloride-coated bag containing Ageless Z-200 in the same manner as in Example 1 When sealed inside, the color changed from blue-violet to vivid red, and this red did not change even after one week.

Example 3 The following filler F was used in place of the filler C in Example 1.
Using the following overprinting agent G instead of overprinting agent D, an oxygen indicator label of the present invention was obtained in the same manner as in Example 1.

Sealant F Acrylic resin containing 5 mol% of N, N-dimethylaminoethyl methacrylate 20 parts Barium sulfate 40 parts Toluene 40 parts Cyclohexane 40 parts Overprinting agent G Acrylic resin containing 5 mol% of vinylpyridine 20 parts Toluene 40 Part Cyclohexane 40 parts When the above label is sealed in a vinylidene chloride-coated bag containing Ageless Z-200 in the same manner as in Example 1, the color changes from blue-violet to vivid red, and this red color changes for one week. No changes were noted afterwards.

Comparative Example 1 The following plug H was used instead of plug C in Example 1.
Was prepared in the same manner as in Example 1 except that the following overprinting agent I was used in place of the overprinting agent D, and an oxygen indicator label of a comparative example was obtained.

Sealant H Acid acrylic resin 20 parts Toluene 40 parts Cyclohexane 40 parts Overprinting agent I Acid polyester resin 20 parts Toluene 40 parts Cyclohexane 40 parts The above label was coated with vinylidene chloride containing Ages Z-200 in the same manner as in Example 1. When sealed in a bag, the color changed from blue-violet to vivid red. However,
When left as it is for one week, the red color of the oxygen indicator layer became remarkably faint as compared with Examples 1 to 5, giving a dirty feeling.

(Effects) According to the present invention as described above, by making the oxygen indicator into a label shape, it can be easily fixed to the inner surface of the packaging bag or the surface of the non-packaged article, the oxygen detection is sharp, and the external detection Is easy, and problems such as incorrect colors do not occur.

Further, by forming an oxygen indicator layer on a filler layer composed of a neutral to alkaline resin, and laminating an overprint layer composed of a neutral to alkaline resin on the surface of the oxygen indicator layer, the gas barrier property is improved. It neutralizes the acid components such as carbon dioxide in the bag and / or the acidity of the paper used as the base material, so that the developed hue is kept clear for a long time.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a cross section of the oxygen indicator label of the present invention. 1: Sheet base material 2: Sealant layer 3: Oxygen indicator layer 4: Overprint layer

Claims (3)

(57) [Claims] 1. A sealing agent layer, an oxygen indicator layer and an overprint layer are laminated on the surface of a sheet-like substrate in the order described above, and the above-mentioned sealing agent layer and overprint layer are formed from a neutral to alkaline resin. An oxygen indicator label characterized by being made. 2. The oxygen indicator label according to claim 1, wherein the filler layer and the overprint layer are formed from an alkaline resin. 3. The oxygen indicator label according to claim 1, wherein the sheet-like substrate is an acidic paper.