JP3217824B2 - Packaging material with oxygen detection function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packaging material capable of easily detecting oxygen inside a package.

[0002]

2. Description of the Related Art Conventionally, as a packaging method for preventing the contents inside a package from being oxidized, a method of vacuum packaging in a bag made of a vinylidene chloride resin-coated film having excellent gas barrier properties, or a similar bag is used. A method of simultaneously sealing the contents and the oxygen scavenger to eliminate the oxygen inside has been performed. 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 enters the bag, the pigment in a reduced state is oxidized to form a color, and a bag is formed. It has the effect that the presence of oxygen inside can be detected with the naked eye.

However, in the case of the above-mentioned conventional tablet-type oxygen indicator, it is difficult to fix the tablet to the inner surface of the bag or the surface of the non-packaged article, so that the tablet moves in the bag and becomes invisible from the outside. There are various problems, for example, tablet may be broken and powder may be generated. Therefore, an object of the present invention is to form a packaging material in a layered form, and by providing an oxygen indicator layer in the layer, it is easy to detect the presence or absence of oxygen due to discoloration of the oxygen indicator, which adversely affects the contents in hygiene. An object of the present invention is to provide a packaging material having an oxygen detecting function without any problem.

[0004]

The above objects are achieved by the present invention described below. That is, the present invention provides a primer coat layer on a gas-impermeable transparent resin sheet as a packaging material.
An oxygen indicator layer is provided via a sealant layer formed by laminating a sealant layer with a gas-permeable resin via an adhesive layer so as to cover the oxygen indicator layer. Packaging bag.

[0005]

An oxygen indicator layer is provided on a gas-impermeable transparent resin sheet, and a sealant layer is laminated with a gas-permeable resin via an adhesive layer so as to cover the oxygen indicator layer. It is possible to provide a packaging material having an oxygen detecting function that can easily detect the presence or absence of oxygen due to the discoloration of the indicator and does not adversely affect the contents on hygiene.

[0006]

The present invention will now be described in more detail with reference to the drawings illustrating preferred embodiments. FIG.
It is a figure which illustrates the partial cross section of one Example of the packaging material which has the oxygen detection function of this invention graphically. In the packaging material having an oxygen detecting function of the present invention, an oxygen indicator layer (3) is preferably formed on a transparent resin sheet (1) via a primer coat layer (2) as shown in FIG. This is a configuration in which a sealant layer (5) is laminated via a layer (4). In the present invention, the transparent resin sheet (1) to be used has gas impermeability and the discoloration of the oxygen indicator layer must be visually confirmed from the surface side. Examples thereof include polyvinyl alcohol, polyethylene terephthalate, nylon, and other polymers coated with polyvinylidene chloride.

It is preferable to form a primer coat layer (2) on the transparent resin sheet (1) in order to improve the adhesion of the oxygen indicator layer (3). Examples of primers that can be used include polyester polyurethane, vinyl chloride-vinyl acetate copolymer, chlorinated polypropylene, chlorinated ethylene / vinyl acetate copolymer, and the like.
Any general one can be used, but it is necessary to select which one to use depending on the material of the transparent resin sheet and the like. Examples of the method for forming the primer coat layer (2) include a printing method such as gravure printing or a coating method. The oxygen indicator layer (3) formed on the primer coat layer (2) is formed from an oxygen indicator ink or paint. One example of an oxygen indicator ink or paint contains a pigment that changes color upon oxidation or reduction.

[0008] Dyes used in oxygen indicator inks or paints are discolored (colored, decolored) in an oxidized state and a reduced state.
Any known dye may be used as long as it is a dye, but a preferable dye is a dye that is colored in an oxidized state and is colorless or pale in a reduced state. Specific examples of preferable dyes include the following dyes. . (1) As basic structure

Embedded image A thiazine dye having; for example, methylene blue or the like;
(2) As a basic structure

Embedded image Indigo dyes having the following formulas: for example, potassium indigo sulfonate;

Embedded image (4) As a basic structure, such as a thioindigoid dye having the formula:

Embedded image (R represents -H, an alkyl group or an allyl group); I. Sulfur Blue 7 and the like, and a particularly preferred dye is the thiazine dye of the above (1). The dyes described above can be used in an oxidized state or a reduced state.

The above dye can be used alone in a reduced state, but it is preferable to use a reducing agent in combination to enhance the stability of the oxygen indicator layer (3). In addition, the dye can be used in an oxidized state, and in this case, a combined use of a reducing agent is essential. That is, in this case, the color development state is caused by 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. 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 form color due to over-reduction, and the dye may be insufficiently retained, for example, the reducing agent itself may be oxidized by oxygen in the air. Need to do.
From such a viewpoint, it is preferable to use a reducing agent which has low reducibility of the dye at room temperature and is hardly oxidized by oxygen in air at room temperature.

Preferred as such a weak reducing agent are reducing saccharides. Examples of such reducing saccharides include monosaccharides such as D-maltose, D-glucose, D-fructose, D-esulose and D-arabinose. Maltose;
A reducing saccharide comprising a glycosidic bond of a monosaccharide molecule such as lactose can be mentioned, and a resin acid having a hydroxyl group such as ascorbic acid can also be used. The use amount thereof is preferably 1 to 100 parts by weight based on 1 part by weight of the dye. It is preferable that an appropriate alkaline substance is present in the indicator ink or paint, and any such alkaline substance may be used as long as it comes to pH 8 or more upon contact with water. , Potassium hydroxide, 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-ethylhexanoate Examples include hydroxides such as salts, carboxylate salts, various salts, and the like. Magnesium hydroxide is particularly preferred from the viewpoint of long-term stability. The amount used is 1 to 1 part by weight of the dye.
500 parts by weight are preferred.

Examples of suitable binders for converting the above dyes and the like into inks or coatings include, for example, ethyl cellulose, ethyl hydroxyethyl cellulose, and ethyl cellulose.
One or more kinds of cellulose derivatives such as cellulose acetyl propionate, butyral resin, polyester resin, acrylic resin, polyether resin, 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,
Ketones such as methyl isobutyl ketone, alcohols such as methanol, ethanol and isopropyl alcohol,
Further, 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 solvent 10
It is preferable to dissolve or disperse 5 to 100 parts by weight with respect to 0 parts by weight. The ink or paint for forming the oxygen indicator layer is obtained by dissolving or dispersing the above-mentioned component system at 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 means such as a sand mill, a ball mill, a roll mill, and an attritor. It is desirable to make it into an ink or a paint.

[0012] By adding a polyhydric alcohol such as glycerin or ethylene glycol in the above-mentioned ink or paint in an amount of about 5% by weight based on the whole, when the oxygen indicator layer comes into contact with oxygen, It is effective in accelerating the discoloration or decoloration of the dye. In addition, various additives and auxiliaries such as nonionic surfactants can be added to the ink or paint. The ink or paint is prepared in a two-pack type, that is, a dye A and a reducing agent are added to a binder liquid to prepare a liquid A, while an alkaline substance is added to a binder liquid to prepare a liquid B. By mixing and using both solutions immediately before forming the oxygen indicator layer, the storage stability of the ink or paint can be improved. Further, the above-mentioned ink or paint is not reduced in the system of the composition, 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 or paint.

The indicator ink or paint constituted as described above is applied to the transparent resin sheet, preferably the primer coat layer, by a printing method such as gravure printing, offset printing, letterpress printing, screen printing or a coating method. After that, by drying, an oxygen indicator layer is formed. The coating amount of the oxygen indicator layer is preferably about 1 to ²⁰ g / m ² (at the time of drying). If the coating amount is less than 1 g / m ² , there is a problem that the color of the oxygen indicator layer is faint and it is not easy to detect discoloration of the indicator layer due to the presence or absence of oxygen. On the other hand, the coating amount is 20 g. If it exceeds / m ² , the oxygen indicator layer rises convexly, which is not preferable in appearance. Moreover, it is not preferable in terms of cost. Further, the oxygen indicator layer may be printed twice in order to obtain an optimum coating amount. Next, a sealant layer (5) is formed via an adhesive layer (4), which may be performed by a conventionally known dry lamination method. As the adhesive to be used, any of vinyl-based, acrylic-based, polyamide-based, epoxy-based, rubber-based, and urethane-based adhesives can be used, but a urethane-based solvent-based adhesive is particularly preferable in terms of strength. A sealant layer (5) is formed on the adhesive layer (4). As the resin used for the sealant layer (5), a gas-permeable resin is used because it is necessary to allow oxygen to penetrate to the oxygen indicator layer (3). For example, low density polyethylene, linear low density polyethylene,
Examples include polypropylene, ionomer, and ethylene-vinyl acetate copolymer. Further, from the viewpoints of processing speed and cost, there is no problem even when laminating by a solventless lamination method using a solventless adhesive as an adhesive. Also, whether to select dry lamination method or solventless lamination method,
An appropriate method may be selected according to the required performance and cost of the product.

[0014]

Next, the present invention will be described more specifically with reference to examples. First, a printing ink having the following composition was prepared. A ink methylene blue 0.15 parts by weight Safranin T 0.10 parts by weight Cellulose acetate propionate 30 parts by weight Fructose 15 parts by weight Ethylene glycol 10 parts by weight Ethyl acetate 22.5 parts by weight Isopropyl alcohol 22.5 parts by weight

B ink Magnesium hydroxide 40 parts by weight Cellulose acetate propionate 25 parts by weight Ethyl acetate 17.5 parts by weight Isopropyl alcohol 17.5 parts by weight Primer solution Polyester urethane 30 parts by weight Vinyl chloride-vinyl acetate copolymer 20 Parts by weight methyl ethyl ketone 15 parts by weight toluene 15 parts by weight ethyl acetate 15 parts by weight isopropyl alcohol 5 parts by weight

The primer solution and the mixed ink of A ink and B ink (mixed immediately before printing) were applied to a polyethylene terephthalate film coated with polyvinylidene chloride having a thickness of 12 μm in a solid content of 2 g / m ² and 10 g / m, respectively, in this order. It was applied and dried at a rate of m ² . A 30 μm-thick polypropylene film was laminated on the printed matter by a dry lamination method using a urethane-based two-component curable adhesive to obtain a packaging material having an oxygen detection function of the present invention. When a bag was made using this packaging material and sealed with an oxygen scavenger, the oxygen indicator layer changed from bluish purple to vivid pink. When a needle-hole-shaped perforation was made in this packaging bag to provide oxygen permeability, the oxygen indicator layer turned blue violet. However, the rate of change is slightly slower than the conventional oxygen indicator label (time to change from blue-violet to pink: 5
Time → 24 hours).

[0017]

According to the present invention, when the packaging material having the oxygen detecting function of the present invention is used to make a bag, discoloration of the oxygen indicator layer can be easily confirmed from the outside, and the oxygen indicator layer is a constituent layer of the packaging material. Therefore, fragments of the oxygen indicator do not leak into the inside of the packaging bag and come into contact with the contents, so that there is no hygiene problem.
Further, since the discoloration speed is slightly slower than that of the conventional oxygen indicator label, it is suitable for long-term storage such as a cleaning bag (for controlling insects on clothes).

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a partial cross section of a packaging material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Permeable resin sheet which has gas impermeability 2 ... Primer coat layer 3 ... Oxygen indicator layer 4 ... Adhesive layer 5 ... Sealant layer

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 31/22 G01N 31/00

Claims (2)

(57) [Claims] 1. An oxygen indicator layer is provided on a gas-impermeable transparent resin sheet as a packaging material via a primer coat layer, and a sealant is formed of a gas-permeable resin so as to cover the oxygen indicator layer. A packaging bag comprising a packaging material having an oxygen detecting function, wherein the layers are laminated via an adhesive layer. 2. The packaging bag having an oxygen detecting function according to claim 1, wherein the oxygen indicator layer is formed from an ink or a paint containing a coloring matter and a reducing agent.