JPH04151554A - Oxygen indicator label - Google Patents

Abstract

PURPOSE:To make it possible to detect oxygen sensitivity from the outside by laminating a filler agent layer, an oxygen indicator layer and an over-print layer in this sequence on the surface of a sheet-shaped substrate, and fixing the label to the inner surface of a packing bag and the non-packed article. CONSTITUTION:A filler agent layer 2 comprising neutral - alkali resin, an oxygen indicator layer 3 and an over-print layer 4 comprising neutral - alkali resin are laminated in this sequence on a sheet-shaped substrate 1. As the sheet-shaped substrate 1, any of neutral paper, alkali paper, acidic paper, synthetic paper, plastic film, metal foil and the like can be used. The filler agent layer 2 is formed by adding a suitable additive into the solution or the dispersing liquid of the neutral - alkali resin as required and by, e.g. photogravure printing. The oxygen indicator layer 3 is formed of oxygen indicator ink containing a coloring matter which is discolored by oxidation and reduction such as, e.g. methylene blue. The over-print layer 4 can be formed by the same way as the formation of the filling agent layer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an oxygen indicator label, and more specifically, provides an oxygen indicator label that is easy to handle and has excellent oxygen detectability.

(Prior art and its problems) Conventionally, packaging methods for products that are easily deteriorated by oxygen, such as foods, include vacuum packaging in bags made of vinylidene chloride resin coated film, which has excellent gas barrier properties, and similar bags. A method of sealing food, etc. and an oxygen absorber at the same time is used to eliminate the oxygen inside.

In these packaging methods, even if the bag has excellent gas barrier properties, oxygen may permeate inside the bag over a long period of time, or if the bag is accidentally damaged, oxygen may enter the bag, causing damage to the packaged goods. There is a problem of deteriorating the quality of

In such cases, an oxygen indicator containing a dye that develops or changes color depending on the presence of oxygen is used as a method for determining the presence or absence of oxygen inside the bag. The oxygen indicator is made up of a tablet consisting mainly of a pigment in a reduced state and a filler, which is enclosed in a bag, and when oxygen permeates or penetrates into the bag, the pigment in a reduced state is oxidized. It develops a color and has the ability to detect with the naked eye the presence of oxygen within the bag.

However, in the case of the above-mentioned conventional tablet-shaped indicators, it is difficult to fix them to the inner surface of the bag or the surface of non-packaged items, so the tablets move within the bag and cannot be seen from the outside.
There are various problems such as the tablets crumbling into powder, or being accidentally ingested by young children.

As a means to solve the above-mentioned problems, the present inventor previously proposed a label-type oxygen indicator. This label-type oxygen indicator is very easy to use and has no risk of being accidentally ingested, but the color developed inside the gas barrier bag may change over time.
There was a problem that the coloring became pale, resulting in poor color development stability and reduced function as an indicator.

Therefore, an object of the present invention is to provide an oxygen indicator that has the advantages of a label type and also has excellent color stability.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, in the present invention, a plug layer, an oxygen indicator layer, and an overprint layer are laminated on the surface of a sheet-like base material in the order described above, and the plug layer and the overprint layer are made of a neutral to alkaline resin. It is an oxygen indicator label characterized in that:

(Function) By making the oxygen indicator in the form of a label, it can be easily fixed to the inner surface of packaging bags or the surface of non-packaged items, and oxygen detection is sensitive and can be easily detected from the outside, as well as preventing accidental ingestion. Such problems do not occur.

In addition, by forming an oxygen indicator layer on a plug layer made of a neutral to alkaline resin and laminating an overprint layer made of a neutral to alkaline resin on the surface of the oxygen indicator layer, gas barrier properties can be improved. It neutralizes acidic components such as carbon dioxide gas in the bag and/or the acidity of the paper used as the base material, so the developed color remains clear for a long period of time.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

As shown in the first diagram, the oxygen indicator label of the present invention comprises a sheet-like base material 1, an eye cream layer 2 made of a neutral to alkaline resin, an oxygen indicator layer 3, and an overprint made of a neutral to alkaline resin. It is characterized in that the layers 4 are laminated in the order described.

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

The eye cream layer 2 formed on the sheet-like base material 1 is particularly useful when paper is used as the sheet-like base material, 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 for the ink described below.On the other hand, the alkaline resin includes an alkaline substance such as the one described below in addition to the above neutral resin. Examples include those added.

Examples of particularly preferred alkaline substances include alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide, and barium hydroxide. Examples of other alkaline resins include acrylic acid resins, maleic acid resins, etc. (alkali metal salts of resins having carboxyl groups in the molecule, resins having phenolic hydroxyl groups such as phenolic resins, and amines). Examples include cationic resins having primary to quaternary nitrogen atoms such as salt, polyethyleneimine, polyvinylcarbazole, polyvinylpyridine, and poly(aminoalkyl acrylate).

The filler layer is formed by adding appropriate additives as necessary to the solution or dispersion of the above-mentioned neutral to alkaline resin, and printing this by, for example, gravure printing, offset printing, letterpress printing,
By printing methods such as screen printing or coating methods,
It is formed by applying it to the surface of the sheet-like base material and then drying it. The mouth sealant layer has a ratio of 1 to Log/rr? (during drying).

The oxygen indicator layer formed on the sealant layer is formed from an oxygen indicator ink.

One example of an oxygen indicator ink contains a pigment that changes color upon oxidation and reduction.

The pigment used in the indicator ink may be any known pigment as long as it changes color (coloring, decoloring) in the oxidized state and reduced state, but preferred pigments are colored in the oxidized state and colorless or colorless in the reduced state. It is a dye that gives a light color,
Specific examples of preferred dyes include the following dyes.

For example, methylene blue, etc.; Indigoid dyes having, for example, sulfonic acid potassium salt, etc.; Thioindigoid dyes having indigo; Mikethrene Brilliant Pink R, etc. (R is -H, alkyl group, allyl Examples include C,1, sulfur-proof, etc. Particularly preferred dyes are the thiazine dyes mentioned in (1) above. Dyes such as those mentioned above can be used in either the oxidized state or the reduced state.

The above dyes can be used alone as long as they are in a reduced state, but
It is preferable to use a reducing agent in combination in order to improve the stability during inventory during label manufacture.

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, the label is colored due to the presence of oxygen in the air, but when it is sealed in a bag together with an oxygen absorber, the reducing agent used in conjunction with the label acts to reduce the pigment and change the color. If oxygen enters the bag which is maintained in this state, the dye will be oxidized again and change 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, but in the case of a strong reducing agent such as hydrosulfide, the reducing agent may over-reduce the dye. It may reduce the pigment and make it incapable of producing color.
Furthermore, when storing the label, the reducing agent itself may be oxidized by oxygen in the air, and the resulting label may not have sufficient shelf life, so it is necessary to select a dye.

From this point of view, it is preferable to use a reducing agent that has a low reducing property of the dye at room temperature and is not easily oxidized by oxygen in the air at room temperature.

Preferable such weak reducing agents are reducing saccharides, and examples of such reducing saccharides include D-maltose, D-
Glucose, D-Fructose, D~Ethasulose, D
- Monosaccharides such as arabinose; examples include reducing oligosaccharides consisting of glycosidic bonds of monosaccharide molecules such as maltose and lactose; fatty acids having hydroxyl groups such as ascorbic acid can also be used. The amount used is 1 of the above pigments.
It is preferably 1 to 100 parts by weight.

In addition, it is preferable to coexist an appropriate alkaline substance in the indicator ink. As such an alkaline substance, any substance that has a pH of 8 or higher upon contact with water may be used, such as sodium hydroxide, water, etc. Potassium oxide, sodium carbonate, potassium carbonate, calcium hydroxide, calcium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate, magnesium hydroxide, sodium acetate, potassium acetate, potassium sodium tartrate, potassium 2-ethylhexanoate salt, etc. Examples include hydroxides, carboxylates, and various salts. Magnesium hydroxide is particularly preferred from the viewpoint of long-term stability. The amount used is preferably 1 to 500 parts by weight per 1 part by weight of the above dye.

Suitable binders for converting the above pigments into ink include:
For example, suitable examples include one or more of cellulose derivatives such as ethyl cellulose, ethyl hydroxyethyl cellulose, and cellulose acetyl propionate, butyral resin, polyester resin, acrylic resin, polyether resin, polyamide resin, and petroleum-based resin. It will be done.

These binders are preferably aromatic binders such as toluene and xylene, ester binders such as ethyl acetate and butyl acetate, ketone binders such as methyl ethyl ketone and methyl isobutyl ketone, alcohol binders such as methanol, ethanol and isopropyl alcohol, and even It is used after being dissolved or dispersed in an organic solvent such as ethylene glycol monoethers or glycols such as ethylene glycol, or in water.

The above binder is added in an amount of 5 to 100 parts by weight per 100 parts by weight of the solvent.
It is preferable to dissolve or disperse parts by weight before use.

The ink composition for forming the oxygen indicator layer is
5 to 4 parts of the above component system is added to 100 parts by weight of the above resin solution.
It can be obtained by dissolving or dispersing it in a proportion of 0 parts by weight. The method for dissolving or dispersing this is to mix all the ingredients and knead them using a general means such as a sand mill, ball mill, roll mill, or attritor. It is desirable to

In addition, by adding polyhydric alcohol such as glycerin or ethylene glycol to the above ink composition in an amount of about 5% by weight based on the total amount, the color change or disappearance of the pigment when the label comes into contact with oxygen is prevented. Effective in speeding up color. In addition, various additives and auxiliary agents such as nonionic surfactants can also be added to the ink composition.

Further, the above ink is prepared in a two-component type, that is, a dye and a reducing agent are added to the binder solution to prepare a solution A, and an alkaline substance is added to the binder solution to prepare a solution B, and both of these solutions are prepared. By mixing and using the dye immediately before forming the oxygen indicator layer, the storage stability of the ink can be improved. Furthermore, the above ink composition contains a dye that is not reduced within the system of the composition and that is necessary for the oxygen indicator. By separately adding other pigments of different colors, it is possible not only to develop a color from colorless to colored, but also to change from colored to a color with a different hue. As such pigments, general pigments and dyes that have been widely used as coloring agents for printing inks, paints, etc. can be used as they are. These other pigments can be added in an amount of about 0.05 to 5% by weight based on the entire ink composition.

The indicator ink composition configured as above,
For example, the oxygen indicator layer is formed by applying it to at least one side of the sheet base material by a printing method such as gravure printing, offset printing, letterpress printing, or screen printing, or by a coating method, and then drying it. The oxygen indicator layer has a content of 1 to 20 g/rrr (dry)
It is preferable to set it as approximately. If the thickness of the indicator layer is thick, it is preferable to apply or print multiple times.For example, if the thickness exceeds 5g/rrr, repeat the application or printing two or more times to ensure good ink adhesion and It is possible to form a layer in which discoloration is clearly visible.

Furthermore, in the present invention, an overprint layer 4 made of the same neutral to alkaline resin as described above is formed on the surface of the oxygen indicator layer for the purpose of preventing the ink layer from falling off, improving surface characteristics, and improving color development stability.

In this case, it is desirable that either the eyelid layer or the overprint layer be permeable to oxygen. A simple method for making oxygen permeable is to use a suitable granular additive.

The overprint layer is formed in the same way as the indicator layer by applying a suitable resin solution or dispersion to the indicator layer by a printing method such as gravure printing, offset printing, letterpress printing, or screen printing, or by a coating method. It is formed by applying it to the surface and then drying it. The overprint amount is preferably about 1 to 10 g/rrr (dry).

(Example) Next, the present invention will be explained in more detail by giving examples and comparative examples. It should be noted that unless otherwise specified, the terms in the text or % are based on weight.

A printing ink having the following composition was prepared.

Cup: Shinketsu Methylene Blue 0.15 parts Safranin T O, 10 parts Cellulose Acetate Propionate 30 parts Fructose 15 parts Ethylene Glycol 10 parts Toluene
22.5 parts isopropyl alcohol
22.5 parts Magnesium hydroxide 40 parts Cellulose acetate propionate 25 parts Toluene 17.5 parts Isopropyl alcohol 17.5 parts Fastener engineered cyclized rubber resin 20 parts Magnesium hydroxide 60 parts Toluene
60 parts cyclohexane
60 parts Overprint ID Cyclized rubber resin 20 parts Sodium carbonate 3 parts Toluene
40 parts cyclohexane
40 copies Example 1 A mixed ink of filler C1A ink and B ink (indicator ink, mixed just before printing) was applied on sterile paper (DPS, 60 g/I) manufactured by Sanyo Kokusaku Valve ■ using a gravure printing machine. and overprint agent in solid content of 2g1rd, 5.0g/r+f and 1g/rrr respectively in this order.
The mixture was coated and dried at a ratio of 1,000 ml, and cut into a predetermined size to obtain an oxygen indicator label of the present invention. Note that the indicator layer was formed by printing twice.

Replace the above label with the oxygen scavenger made by Mitsubishi Gas Chemical (Ageless Z).
-200) was sealed in a vinylidene chloride-coated bag, and the indicator layer changed from bluish-purple to bright red, and no change in the red color was observed even after one week.

Example 2 An oxygen indicator label of the present invention was obtained in the same manner as in Example 1 except that the following filler E was used instead of filler C in Example 1.

-Acrylic resin containing 2 mol% of sodium acrylate
20 parts calcium carbonate
40 parts toluene
40 parts cyclohexane 40
The above label is attached to Ageless Z-200 in the same way as in Example 1.
When sealed in a polyvinylidene chloride-coated bag containing
No change was observed even after a week.

Example 3 The present invention was carried out in the same manner as in Example 1, except that the following filler F was used instead of filler C in Example 1, and the following overprint agent G was used instead of the overprint agent. Obtained an oxygen indicator label.

Acrylic resin containing 5 mol% of N,N-dimethylaminoethyl methacrylate 20 parts barium sulfate
40 parts toluene
40 parts cyclohexane 4
0 parts Overprint agent 20 parts of acrylic resin containing 5 mol% of nylpyridine 40 parts of toluene 40 parts of cyclohexane
Similarly, when the bag was sealed in a vinylidene chloride-coated bag containing Ageless Z-200, the color changed from blue-purple to bright red, and no change in the red color was observed even after one week.

Comparative Example 1 A comparative example was carried out in the same manner as in Example 1, except that the following filler H was used instead of filler C in Example 1, and the following overprint agent was used instead of overprint agent. Obtained an oxygen indicator label.

■-Kundan acidic acrylic resin 20 parts toluene
40 parts cyclohexane
40 parts Overbrush II Acidic polyester resin 20 parts Toluene
40 parts cyclohexane
40 copies The above label was sealed in a vinylidene chloride coated bag containing Ageless 2-200 as in Example 1 (and the color changed from bluish-purple to bright red. However, the color changed from bluish-purple to bright red. As a result, the red color of the oxygen indicator layer became significantly lighter than in Examples 1 to 5, giving it a dirty appearance.

(Effects) According to the present invention as described above, since the oxygen indicator is in the form of 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, and the oxygen indicator is in the form of a label. Detection is easy and problems such as accidental ingestion do not occur.

In addition, by forming an oxygen indicator layer on a sealant layer made of a neutral to alkaline resin and laminating an overprint layer made of a neutral to alkaline resin on the surface of the oxygen indicator layer, gas barrier properties can be improved. It neutralizes acidic components such as carbon dioxide gas in the bag and/or the acidity of the paper used as the base material, so the developed color remains clear for a long period of time.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating a cross section of an oxygen indicator label of the present invention. : Sheet-like base material 2 Roll-inhibiting agent layer 3 : Oxygen indicator layer 4 Niober print layer

Claims (3)

[Claims] (1) A filler layer, an oxygen indicator layer, and an overprint layer are laminated on the surface of a sheet-like base material in the order described above, and the filler layer and overprint layer are formed from a neutral to alkaline resin. Oxygen indicator label featuring: (2) The oxygen indicator label according to claim 1, wherein the sealant layer and the overprint layer are made of an alkaline resin. (3) The oxygen indicator label according to claim 1, wherein the sheet-like base material is acidic paper.