JPH04151560A - Oxygen indicator label - Google Patents

Abstract

PURPOSE:To make it possible to detect oxygen sensitively from the outside by laminating 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 surface of a non-packed article. CONSTITUTION:An oxygen indicator layer 2 is provided on a sheet-shaped substrate 1, and an over-print layer 3 comprising neutral - alkali resin is further provided on the surface of the layer 2. As the sheet-shaped substrate 1, any of various kinds of papers, plastic films, metal foils and the like can be used. When the paper is used as the substrate, a filler agent layer 4 is formed, and the oxygen indicator layer 2 is formed on the layer 4. The oxygen indicator layer 2 is formed of oxygen indicator ink or paint containing a coloring matter which is discolored by oxidation and reduction. It is preferable that alkali material such as sodium hydroxide is contained in the indicator ink or paint. The over-print layer 3 is provided for preventing the falling of the ink or paint layer and for preventing the change in the hue and the hypochromatic change of the colored indicator.

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, as a packaging method for products such as foods (which are easily deteriorated by oxygen), vacuum packaging in bags made of vinylidene chloride resin-coated film, which has excellent gas barrier properties, and similar packaging methods have been used. A method of sealing food, etc. and an oxygen absorber in a bag at the same time eliminates 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 containing mainly a dye in a reduced state and a filler, which is enclosed in a bag, and when oxygen permeates or penetrates into the bag, the dye 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 may move within the bag and become invisible from the outside, or the tablets may collapse. There are various problems such as powder generation and accidental ingestion by 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 accidental ingestion, but the color developed inside the bamboo gas barrier 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, the present invention provides an oxygen indicator layer and an overprint layer laminated on the surface of a sheet-like base material in the order described above, and the overprint layer is formed from a neutral to alkaline resin. It is an indicator label.

(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 coating the oxygen indicator layer with a neutral to alkaline resin, the acid components such as carbon dioxide gas during gas barrier production and/or the acidity of the paper used as the base material are neutralized, so the color tone is reduced. Retains clarity for a long 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 includes an oxygen indicator layer 2 provided on a sheet-like base material 1,
Furthermore, it is characterized in that an overprint layer 3 made of a neutral to alkaline resin is provided on the surface thereof.

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.

In particular, when paper is used as a sheet-like base material, the indicator ink forming the indicator layer may be impregnated into the paper, but in order to improve the oxygen detectability of the oxygen indicator layer, it is preferable to use a sheet as a base material. In order to eliminate irregularities on the surface of the shaped substrate 1 and ink seepage, a sealing layer 4 is formed,
An oxygen indicator layer 2 is formed thereon.

The oxygen indicator layer formed on the sheet-like base material 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 Indigo, such as sulfonic acid potassium salt; Mikethrene Brilliant Pink R, etc. (R represents -H, an alkyl group, an allyl group) Examples include C,1, sulfur-proof, etc. Particularly preferred dyes are the thiazine dyes (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. , is kept in this state. If oxygen then enters the bag, 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 ability to reduce dyes 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.
1 to 10 parts by weight is preferred.

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, a polyhydric alcohol such as glycerin or ethylene glycol is added to the above ink composition in an amount of about 5% by weight based on the total (this prevents discoloration or discoloration of the pigment when the label comes into contact with oxygen). It is effective in accelerating color erasure.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 oxygen indicator layer immediately before forming the oxygen indicator layer, the storage stability of the ink can be improved.Furthermore, the above ink composition contains an oxygen indicator wear dye that is not reduced within the composition system and is used as an oxygen indicator wear dye. By separately adding other pigments of different colors, it is possible not only to change the color from colorless to colored, but also from colored to a color with a different hue. Common pigments and dyes that are widely used as colorants for inks and paints can be used as they are.These other pigments are added in an amount of about 0.05 to 5% by weight based on the total ink composition. You can.

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 preferably has a density of about 1 to 20 g/rd (dry). 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/rd, repeat the application or printing two or more times to improve ink adhesion.
Moreover, it is possible to form a layer in which discoloration is clearly visible.

Furthermore, in the present invention, in order to prevent the ink layer from falling off and to prevent the colored oxygen indicator from changing in hue or becoming lighter in color, a neutral to alkaline, preferably alkaline resin is added on the oxygen indicator layer. A transparent overprint layer 3 is formed. In this case, there is no problem as long as the overprint layer is oxygen permeable, but if it is oxygen impermeable, it is preferable to use a gas permeable sheet such as paper as the sheet-like base material.

The neutral resin used in the present invention includes the same resin as the resin used as the binder of the above-mentioned ink.On the other hand, the alkaline resin includes the above-mentioned alkaline substance added to the above-mentioned neutral resin. Examples include those added.

Particularly preferred examples of alkaline agents include alkaline earth metal hydroxides such as calcium hydroxide, magnesium hydroxide, and barium hydroxide. Examples of other alkaline resins include alkali metal salts and amine salts of resins having carboxyl groups in their molecules such as acrylic acid resins and maleic acid resins, and resins having phenolic hydroxyl groups such as phenolic resins. , polyethyleneimine, polyvinylcarbazole, polyvinylpyridine, poly(aminoalkyl acrylate), and other cationic resins having primary to quaternary nitrogen atoms.

In the same manner as the formation of the indicator layer, the overprint layer is formed by applying a solution or dispersion of the above-mentioned neutral to alkaline resin by a printing method such as gravure printing, offset printing, letterpress printing, or screen printing, or by a coating method. , is formed by applying it to the surface of the indicator layer and then drying it. The overprint layer is 1 to 1
It is preferable to set it to about 0 g/Ho (when dry).

In addition, in the present invention, it is preferable to provide an adhesive layer 5 on either side of the label obtained above using a conventionally known adhesive, heat-sensitive adhesive, etc. (If this is done,
When using the label, the label can be easily fixed to the inner surface of the bag or the surface of the packaged article.

When the adhesive layer 5 is made of an adhesive, it is preferable to provide a release paper 6 on its surface, and when the adhesive layer 5 is a heat-sensitive adhesive layer, the release paper 6 is not necessary.

Further, as shown in the second figure, it is also possible to provide the adhesive layer 5 on the side of the enzyme indicator layer 2, and in this way,
It has the advantage that it is easy to observe the discoloration when it is attached to the inner surface of the bag.

(Example) Next, the present invention will be described in more detail with reference to 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.

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 L Engineering 2 Tufeng Kai Magnesium Hydroxide 40 parts Cellulose Acetate Propionate 25 parts Toluene 17.5 parts Isopropyl Alcohol 17.5 parts Overprint Qi I
C Cyclized rubber resin 20 parts magnesium hydroxide 3 parts toluene
40 parts cyclohexane
40 copies Example 1 On sterile paper made by Sanyo Kokusaku Valve ■ (DPS, 60 g/I), a gravure printing machine was used to print a mixed ink (indicator ink) of Ichinawate's eye blocker, A ink and B ink. Mixed immediately before) and overprint agent C were applied and dried in this order at a solid content of 2 g/rrr, 5.0 g/rrr, and Ig/e, respectively, and cut into a predetermined size. Obtained indicator label. 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), 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 overprint agent was used instead of overprint agent C in Example 1.

Overprint Qi ID Acrylic resin containing 2 mol% of sodium acrylate
20 parts toluene
40 parts cyclohexane
40 copies When the above label is sealed in a vinylidene chloride coated bag containing Ageless 2-200 in the same way as in Example 1, the color changes from bluish-purple to bright red, and this red remains even after a week. No changes were observed.

Example 3 An oxygen indicator label of the present invention was obtained in the same manner as in Example 1 except that the following overprint agent E was used instead of overprint agent C in Example 1.

Overprint IE Acrylic resin containing 5 mol% of N,N-dimethylaminoethyl methacrylate 20 parts toluene
40 parts cyclohexane
40 copies of the above label, as in Example 1, Ageless 2
When sealed in a vinylidene chloride-coated bag containing -200, the color changed from bluish-purple to bright red, and no change in this red color was observed even after one week.

Example 4 A roll coater was used to coat the back side of the uncut printed matter obtained in Example 1 with Toyo Ink Co., Ltd.
S3233) was coated, and release paper was further attached to form an adhesive sheet. Half-cut the rowing sheet, make it into a label-like adhesive sticker, peel off the female pattern, and place it in a polyvinylidene chloride coated bag containing the same oxygen-reducing agent as in Example 1 and seal it. The color changed from purple to red, and no change in this red color was observed even after one week.

Example 5 A heat sealing agent manufactured by Seitetsu Kagaku ■ (Seiksen A
) or a heat-sealing agent (Seikadyne 1700W) manufactured by Dainichiseika Chemical Industry Co., Ltd., respectively, to make a label, heat-seal each label to the inner surface of a vinylidene chloride-coated bag, add an oxygen absorber, and seal it. The color changed from bluish-purple to red, and no change in this red color was observed even after one week.

Comparative Example 1 An oxygen indicator label of a comparative example was obtained in the same manner as in Example 1 except that the following overprint agent F was used in place of overprint agent C in Example 1.

Overprint F Acidic acrylic resin 20 parts toluene
40 parts cyclohexane
40 copies When the above label was sealed in a vinylidene chloride coated bag containing Ageless 2-200 in the same manner as in Example 1, the color changed from blue-purple to bright red. However, after being left as is for one week, 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 coating the oxygen indicator layer with a neutral to alkaline resin, acid components such as carbon dioxide gas in the air and/or
Or, since it neutralizes the acidity of the paper used as a base material, the developed color hue is maintained clearly for a long period of time.

[Brief explanation of the drawing]

FIGS. 1 and 2 are diagrams illustrating a cross section of an oxygen indicator label of the present invention. 1: Sheet-like base material 2: Oxygen indicator layer 3 Niober print layer 4: Sealing layer 5: Adhesive layer (adhesive layer) 6: M pattern diagram Figure 2

Claims (5)

[Claims] (1) An oxygen indicator label characterized in that 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 overprint layer is made of a neutral to alkaline resin. (2) The oxygen indicator label according to claim 1, wherein the overprint layer is formed of an alkaline resin. (3) The oxygen indicator label according to claim 1, wherein the sheet-like base material is acidic paper. (4) The oxygen indicator label according to claim 1, wherein a sealing layer is formed between the sheet-like base material and the printing ink layer. (5) The oxygen indicator label according to claim 1, wherein an adhesive layer or a heat-sensitive adhesive layer is formed on the front or back surface.