JP4760383B2 - Oxygen indicator and packaging material containing oxygen indicator - Google Patents

Description

  The present invention relates to an oxygen indicator for determining a deoxygenated state by an oxygen absorbent, and an oxygen indicator and a packaging material containing the oxygen indicator, which can improve printability, extend the life of an ink, and prevent poor color development. It is about.

  Oxygen is known to oxidize foods and pharmaceuticals due to its high reactivity and to denature and degrade the active ingredients of products. For this reason, many foods and pharmaceuticals prevent the oxidation by reducing the oxygen concentration in the package by coexisting an oxygen absorbent in the package, or by replacing the inert gas when filling the contents. In addition, an oxygen indicator is simultaneously placed inside the package so that there is no oxygen ingress due to the capacity of the oxygen absorbent, pinholes in the package, or poor sealing, and the contents are stored in a deoxygenated state. It has been thrown.

  Currently, several types of oxygen indicators are available on the market, with different combinations of redox dyes, reducing agents, binder resins, etc. Many oxygen indicators make use of the property that the redox dye exhibits different colors between the reduced and oxidized types. In particular, there are many that use methylene blue, and the oxygen indicator using methylene blue exhibits a reduced type, that is, colorless by the action of a reducing agent under deoxygenation, and is oxidized by oxygen in the atmosphere and exhibits blue. (For example, refer to Patent Document 1.) In addition to tablets, the oxygen indicator has been developed in liquid, ink, sheet, and paper types, and further integrated with oxygen absorbers and packaging materials. Have been developed to save labor at the time of input and facilitate detection discrimination.

  The reducing agents generally used are mostly those in which an alkaline substance coexists with reducing sugars such as glucose, or ascorbic acid from the viewpoint of safety and health. However, when a packaging body provided with an indicator function is subjected to high-temperature sterilization treatment, the above-mentioned reducing agent usually used has a drawback that it has poor heat resistance and decomposes by heat. Therefore, there is a possibility that the function may be deactivated, and it is necessary to change the reducing agent. Suitable reducing agents include alcohol amines and polyhydric alcohols having a relatively high boiling point. If these are mixed with a redox dye and sterilized at a high temperature, the color tone can be changed from an oxidized color to a reduced color.

  When applying an ink composition for oxygen indicator to a substrate, reducing agents such as alcohol amines and polyhydric alcohols with high viscosity and relatively high boiling point will significantly reduce the ink adhesion to the substrate if the amount added is large. It has the property to make. Therefore, there is a high possibility that problems such as ink removal occur at the time of printing or unwinding in the next process or contact with the guide roll.

  Furthermore, in the ink composition for oxygen indicator, the redox dye and the reducing agent are mixed as one component, and when the state is long-term, depending on the storage environment, part of the reducing ability is deactivated, or This causes poor coloring of the redox dye.

Prior art documents are shown below.
JP-A 61-144568

  The present invention is intended to solve such problems of the prior art, and in an oxygen indicator for determining a deoxygenated state by an oxygen absorbent, improvement in printability, extension of ink life, and color development. An object of the present invention is to provide an oxygen indicator and a packaging material containing the oxygen indicator that can prevent defects.

The present invention has been made to solve the above problems, and the invention according to claim 1 of the present invention includes an ink composition containing at least a redox dye and an ink composition containing N-methyldiethanolamine . Is an oxygen indicator formed by being applied or printed on a support.

  The invention according to claim 2 of the present invention is the packaging material containing an oxygen indicator according to claim 1, wherein the support is separate from the outer package forming the package.

  The invention according to claim 3 of the present invention is the packaging material containing the oxygen indicator according to claim 1, wherein the support is an outer package forming a package.

According to the invention of claim 1, the oxygen indicator of the present invention is obtained by applying or printing an ink composition containing at least a redox dye and an ink composition containing N-methyldiethanolamine on a support. As a result, it is possible to maintain each state as independent as possible until immediately before the high-temperature sterilization treatment, so that it is possible to suppress the deactivation of the oxygen indicator function due to long-term storage before heat treatment, and prevent poor coloring during long-term storage. become able to. Moreover, the adhesion defect to the base material of the ink composition for oxygen indicators can be improved by limiting the printing order. That is, if a reducing agent (alcohol amines, polyhydric alcohols, etc.) that causes poor adhesion is applied after the second printing, sufficient adhesion strength required for processing can be obtained.

  According to the invention of claim 2, the size of the oxygen indicator is determined by making the support separate from the exterior body forming the package, and simultaneously packaging the contents and enclosing the oxygen indicator in the exterior body. Can be freely changed, and can also be used as a packaging material for an oxygen absorbent, saving space in the packaging container.

  According to the invention of claim 3, since the support body is an exterior body that forms a package, an exterior body with an oxygen indicator can be produced, so that the production process can be streamlined and the total saving of materials can be achieved. As a result, the cost can be reduced. Furthermore, the process of enclosing the oxygen indicator in the exterior body is eliminated and labor is saved.

  The present invention is an oxygen indicator for determining a deoxygenated state by an oxygen absorbent. In order to improve printability and extend the life of the ink, the active ingredient in the ink composition for the oxygen indicator is separated and the printing order is limited. This is an improvement. More specifically, a reducing agent that causes poor adhesion to the substrate is added to the ink that is applied after the second printing to improve printability, and the oxidation-reduction dye and the reducing agent are subjected to high-temperature sterilization treatment. By maintaining the separated state as much as possible until just before, it is possible to extend the life of the ink and to prevent poor coloring. The best mode for carrying out the present invention will be specifically described below.

The ink composition constituting the oxygen indicator of the present invention contains at least a redox dye in the ink applied to the first printing on the substrate, and in the ink applied on the second printing on the substrate, It contains a reducing agent that is stable at least at room temperature. Other ink components include a binder resin and a solvent. For example, when ink is applied using a multicolor printing press, the ink composition constituting the oxygen indicator of the present invention has the same effect even when a continuous printing unit is applied more than once, that is, a plurality of times. Obtainable. However, in practice, it is preferable to apply two inks containing a redox dye and a reducing agent by using two continuous printing units. In the ink composition, a metal catalyst such as a metal oxide or a transition metal complex may be added for the purpose of further promoting the reduction reaction. In addition to promoting the reduction reaction, the metal catalyst can be expected to have an effect of preventing blocking.

  The redox dye used in the present invention is not particularly limited as long as it is a dye that exhibits different colors in an oxidized state and a reduced state, and any known dye can be used. Specifically, in addition to methylene blue, new methylene blue, neutral red, indigo carmine, indigo sulfonic acid potassium salt, safranin T, phenosafranine, capri blue, nile blue, diphenylamine, diphenylamine sulfonic acid, xylene cyanol, nitrodiphenylamine, ferroin, Nitroferroin, N-phenylanthranilic acid and the like can be used.

  As the reducing agent used in the present invention, any reducing agent that exhibits a reducing action when subjected to heat treatment can be used. However, a strong reducing agent such as metal hydride is preferable because it changes the dye. Absent. In addition, reducing sugars that coexist with alkaline substances that exhibit a reducing action at room temperature and ascorbic acid may react with oxygen in the atmosphere and cause a decrease in the capacity of the oxygen indicator, so select a combination of redox dye and reducing agent. It is very important to do. From such a viewpoint, it is preferable to use a mild reducing agent that does not reduce the dye at room temperature, exists stably, and does not react with oxygen in the atmosphere.

  Specifically preferred as such mild reducing agents are n-dibutylamine, n-tributylamine, diisobutylamine, diamylamine, triamylamine, n-heptylamine, 2-ethylhexylamine, dioctylamine, diethylenetriamine, tetraethylene. Alkylamines such as pentamine and cyclohexylamine, 3-amino-1,2-propanediol, 3-amino-1-propanol, 3-amino-2-propanol, aminophenol, monoethanolamine, diethanolamine, triethanolamine , Alcohol amines such as 2-dimethylethanolamine and N-methyldiethanolamine, reducing sugars such as maltose, galactose, glucose, fructose, and lactose (no alkaline substances coexist) Alternatively higher alcohol, ethylene glycol, glycerol, propylene glycol, polyhydric alcohols such as polyvinyl alcohol is generally susceptible to oxidation at high temperature material, such as. Considering safety and hygiene and thermal stability in particular, it is preferable to use N-methyldiethanolamine or glycerol having a high boiling point, and the amount used is 1 to 100 parts by weight with respect to 1 part by weight of the dye. preferable.

  The binder resin is used for fixing the redox dye, the reducing agent, the metal catalyst, and the solvent on the support. Specific examples of binder resins suitable for ink production include cellulose derivatives such as ethyl cellulose, hydroxyl ethyl cellulose, and cellulose acetate, butyral resins, acetal resins, polyester resins having a hydrophilic group introduced therein, acrylic resins, and urethane-ureas. Examples thereof include resins and urethane resins. In particular, in consideration of the solubility of the redox dye and high temperature sterilization treatment such as boiling and retort, it is preferable to use an aqueous resin having heat resistance.

The binder resin is used by being dissolved or dispersed in an organic solvent typified by toluene, xylene, methyl ethyl ketone or ethyl acetate, or an aqueous solvent typified by water, methanol, ethanol or isopropyl alcohol. These solvents may be used alone or in combination with a plurality of solvents.

  By adding a thermally stable metal oxide, an inorganic compound such as zeolite supporting the metal oxide, or a transition metal complex as a metal catalyst, the reduction reaction can be promoted. Specifically, a heterogeneous catalyst such as titanium oxide, zinc oxide, tin oxide, iron oxide or zeolite on which these are not subjected to surface treatment may be used. Furthermore, as homogeneous catalysts represented by Wilkinson complexes, rhodium, ruthenium, cobalt, chromium, molybdenum, tungsten, palladium, platinum and other phosphine complexes, amine complexes, carbonyl complexes, etc., cerium, manganese, cobalt, nickel, etc. Fatty acid salt complexes such as naphthenates, octylates, oleates, octenoates and the like can be used.

  The metal catalyst may be added to any ink composition, but when added to the ink side containing the reducing agent, there is a concern that the ability of the reducing agent may be deactivated over time. In such cases, care should be taken such as storing in a cool and dark place. Furthermore, the addition amount is preferably 20 parts by weight or less with respect to 1 part by weight of the redox dye. If the concentration of the metal catalyst is higher than this, it is not preferable because dispersion of the metal catalyst is difficult and a phenomenon that the adhesion strength with the support is lowered occurs.

  It is also possible to add a commonly used anti-blocking agent separately from the metal catalyst to the ink composition for oxygen indicator of the present invention in order to prevent winding and preventing blocking in the next process. is there. Further, if necessary, a colorant or the like may be added separately from the dispersant, the antifoaming agent, and further the redox dye. Furthermore, for the purpose of improving the adhesion strength with the support and preventing the fading of the pigment, the problem solving effect can be further enhanced by providing anchor coat layers and overcoat layers above and below the ink composition. The coating agent that can be used is not particularly limited as long as it is permeable to oxygen and has good adhesion to the support, or contains an ultraviolet absorbing material and does not interfere with the color development of the oxygen indicator. Can also be used.

  As described above, an oxygen indicator is prepared by applying the ink composition to a support. Printing and coating methods are used for application. As a printing method, a relief printing method, an intaglio printing method, an offset printing method, a screen printing method, and the like can be used. As a coating method, roll coating, spray coating, dip coating, solid coating, and the like are used.

  It is preferable that the support does not react with the ink composition and does not inhibit the coloration of the reagent. Specifically, paper, synthetic paper, non-woven fabric, or synthetic resin film is used. The support is separate from the outer packaging made of a gas barrier packaging material that wraps the contents of food, pharmaceuticals, etc., and the indicator that has the ink composition applied to the support at the same time as the packaging is packaged in the outer packaging. Encapsulate.

Further, the outer package itself for packaging the contents or a part thereof may be used as a support, the ink composition may be applied to the inner surface of the outer package, and the outer package may be used as an indicator. It is necessary to provide an oxygen barrier layer on the outside of the oxygen indicator ink composition for the purpose of preventing oxygen from entering. These materials include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide resins such as polyamide 6 and polyamide 6-polyamide 66, polyamide resins represented by aromatic polyamides such as MXD6, polyacrylonitrile resins, and polyvinyl alcohol resins. Thermoplastic resin layer selected from ethylene-vinyl alcohol copolymer resin, polyvinylidene chloride resin, metal foil layer such as aluminum foil, PVD vapor deposition method such as aluminum, silica and alumina, or organosilane such as hexamethylenedisiloxane And a vapor-deposited thermoplastic resin layer obtained by a CVD vapor deposition method using acetylene gas or other carbon gas sources.

  Examples of the present invention will be specifically described below. The present invention is not limited to this.

<Example 1>
(Ink composition 1)
Methylene blue ... 1.96 parts by weight Aqueous acrylic resin ... 27.45 parts by weight Methanol ... · · · 47.06 parts by weight water ············· 23.53 parts by weight (ink composition 2)
N-methyldiethanolamine ... 10.71 parts by weight Aqueous acrylic resin ... 25.00 parts by weight Methanol ... -42.86 parts by weight Water-21.43 parts by weight.

<Example 2>
(Ink composition 1)
N-methyldiethanolamine ... 10.71 parts by weight Aqueous acrylic resin ... 25.00 parts by weight Methanol ... -42.86 parts by weight water-21.43 parts by weight (ink composition 2)
Methylene blue ... 1.96 parts by weight Aqueous acrylic resin ... 27.45 parts by weight Methanol ... · · · 47.06 parts by weight Water · · · · · · 23.53 parts by weight.

<Example 3>
(Ink composition 1)
Methylene blue ... 1.85 parts by weight Titanium oxide ... 5.56 parts by weight Aqueous acrylic resin ... ... 25.93 parts by weight Methanol ... 44.44 parts by weight Water ... ... 22.22 parts by weight (ink composition 2)
N-methyldiethanolamine ... 10.71 parts by weight Aqueous acrylic resin ... 25.00 parts by weight Methanol ... -42.86 parts by weight Water-21.43 parts by weight.

<Example 4>
(Ink composition 1)
Methylene blue ... 1.96 parts by weight Aqueous acrylic resin ... 27.45 parts by weight Methanol ... · · · 47.06 parts by weight water ············· 23.53 parts by weight (ink composition 2)
N-methyldiethanolamine ··· 10.17 parts by weight Titanium oxide ········ 5.08 parts by weight Aqueous acrylic resin ··· ... 23.73 parts by weight Methanol ... 40.68 parts by weight Water ... 20 34 parts by weight.

<Example 5>
(Ink composition 1)
Methylene blue ... 1.75 parts by weight N-methyldiethanolamine ... 10.53 parts by weight Aqueous acrylic resin ... 24.56 parts by weight Methanol ... 42.11 parts by weight Water ... 21.05 parts by weight Department.

<Example 6>
(Ink composition 1)
Methylene blue ... 1.67 parts by weight N-methyldiethanolamine ... 10.00 parts by weight Titanium oxide ... ... 5.00 parts by weight Aqueous acrylic resin ... 23.33 parts by weight Methanol ... 40.00 parts by weight water ... 20.00 parts by weight.

(Form)
By finely dispersing the ink composition with a paint conditioner or the like, the ink composition 1 of Examples 1 to 6 and the ink composition 2 of Examples 1 to 4 were obtained. Ink composition 1 → Ink composition 2 were printed twice on a corona-treated surface of a 12 μm thick polyester film (PET) in the order of 200 μm and 30 μm gravure plate and dried at room temperature for 12 hours. (However, in Example 5 and Example 6, ink composition 1 was printed twice).

<Experiment 1>
The printed matter for evaluation (oxygen indicator) obtained in Examples 1 to 6 was subjected to a blocking test and a cello tape (registered trademark) peel test to evaluate ink adhesion to the substrate. The results are shown in Table 1.

  A urethane-based two-component curable adhesive is used for the printed matter (oxygen indicator), and an alumina vapor-deposited film and a sealant film are laminated on the upper and lower sides of the PET respectively by a dry laminating method to obtain a packaging material containing the oxygen indicator of the present invention. It was. This packaging material was made into a bag, and an oxygen absorbent was added, and then sealed with nitrogen.

<Experiment 2>
The retort process was performed and the color tone of the oxygen indicator of Examples 1-6 was observed. The results are shown in Tables 1 and 2.

<Experiment 3>
A long-term storage test was conducted, and it was confirmed whether the reducing ability of the oxygen indicators of Examples 1 to 6 was inactivated. The results are shown in Tables 1 and 3.

表１は、酸素インジケーターの総合評価の結果を記す。

Table 1 shows the results of comprehensive evaluation of the oxygen indicator.

表２は、酸素インジケーターの色調を観察した結果を記す。

Table 2 shows the results of observation of the color tone of the oxygen indicator.

表３は、酸素インジケーターの色調を観察した結果を記す。

Table 3 shows the results of observation of the color tone of the oxygen indicator.

<Evaluation>
From Table 1 of Experiment 1, in Examples 1 and 2 and Example 5 in which the ink composition did not contain titanium oxide (TiO ₂ ), blocking due to surface tack was confirmed. Thereby, it turned out that titanium oxide has the blocking prevention effect by roughening the ink surface. In Examples 2, 5 and 6 in which an ink composition containing a reducing agent (N-methyldiethanolamine) was applied to a PET substrate for the first time of printing, a cellotape (registered trademark) peel test was performed. This occurred.

  From Table 1 and Table 2 of Experiment 2, when performing lamination, deoxygenation packaging, and retort treatment (121 ° C.-30 min) immediately after printing, it is possible to confirm a change in color tone from oxidized color to reduced color in all Examples, It was confirmed that the retort ability was satisfactory.

  From Table 1 and Table 3 in Experiment 3, in the one-component type Example 5 and Example 6 in which the redox dye and the reducing agent were mixed as one component, discoloration of the indicator due to long-term storage was confirmed. This was considered to be partly the result of the action of the reducing agent at 25 ° C.

Claims (3)

An oxygen indicator comprising: an ink composition containing at least a redox dye; and an ink composition containing N-methyldiethanolamine applied or printed on a support.   2. The packaging material containing an oxygen indicator according to claim 1, wherein the support is separate from the outer package forming the package.   The packaging material containing an oxygen indicator according to claim 1, wherein the support is an exterior body that forms a packaging body.