JP2007131810A - Ink composition for oxygen indicator, oxygen indicator, packaging material and package - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink composition for oxygen indicator, which has an indicator function for judging the state of deoxidation by an oxygen absorbent and excellent dispersion stability and storage stability, an oxygen indicator having a display part composed of the ink composition and having fastness arranged at least at a part of a substrate, a packaging material and a package. <P>SOLUTION: In the ink composition for an oxygen indicator comprises at least an oxidation-reduction pigment, a reducing agent, a binder resin and a diluent solvent, the binder resin has an acid value of 50-200, preferably 100-200. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention has an oxygen indicator function for determining the state of deoxygenation by an oxygen absorbent or the like, and has an oxygen indicator ink composition excellent in dispersion stability and storage stability, and at least a display portion comprising this ink composition. The present invention relates to an oxygen indicator, a packaging material, and a package provided in a part.

  Conventionally, an ink composition for an oxygen indicator containing a redox dye has generally used a reducing saccharide such as glucose or fructose coexisting with a strong alkali agent such as sodium hydroxide, or ascorbic acid as a reducing agent. Thus, the change in hue exhibited when protons are added to the oxygen-reducing dyes in the oxidized state by the action of these reducing agents to enter the reduced state can be displayed as a measure for determining the deoxygenated state.

  As the vehicle of such an ink composition, cellulose derivatives such as ethyl cellulose, hydroxylethyl cellulose, cellulose acetate, butyral resin, acetal resin, polyester resin having a hydrophilic group introduced, acrylic resin, urethane-urea resin, urethane resin, etc. Is used as a binder resin, and an appropriate one is selected from these depending on the application.

  Oxygen indicator ink compositions composed of such coloring materials and vehicles are required to have long-term performance guarantees and storage stability. However, oxygen indicators having a display portion composed of an oxygen indicator ink composition are boiled. -Since it is also assumed to be used in harsh environments such as hot water treatment such as retort, further robustness in the display section is required.

  However, satisfactory water resistance and heat resistance could not be obtained in a display portion made of an ink composition for an oxygen indicator using a cellulose derivative having many hydroxyl groups or a butyral resin as a binder resin. Therefore, conventionally, a display part (indicator part) formed by using a resin containing a functional group such as a carboxyl group typified by acrylic resin or urethane resin as a binder resin and using a crosslinking agent in combination with this. Is given robustness.

  On the other hand, an ink composition for an oxygen indicator that contains a redox dye and uses the change in hue between the oxidized state and the reduced state as a measure for determining the deoxygenated state is, for example, a highly acidic reducing agent or oxidizing agent. It can be obtained by adding reducing pigments to the vehicle, but if the pH of the entire ink composition changes greatly from the alkaline side to the acidic side, the resin solids of the binder resin that makes up the vehicle will aggregate and settle, making it easier to disperse. In some cases, the stability and storage stability are deteriorated and the color development is weakened.

There is a technique (for example, see Patent Document 1) in which a binder resin having a specific acid value is selectively used to prevent precipitation of a specific blue pigment in an ink composition for ballpoint pens. Even with the technology, at least an oxygen reducing ink composition comprising an oxygen reducing dye, a reducing agent, a binder resin, and a diluent satisfies both dispersion stability, storage stability, and reliable color developability with a redox dye. I couldn't. In particular, when an acidic substance such as ascorbic acid is used as the reducing agent, it has been difficult to uniformly disperse and stabilize the ink components.
JP 2002-371218 A

  The present invention was made in view of the drawbacks of the related art, and has an indicator function for determining the state of deoxygenation by an oxygen absorbent and the like, and an oxygen indicator ink composition excellent in dispersion stability and storage stability; An object of the present invention is to provide an oxygen indicator, a packaging material, and a packaging body provided with at least a part of a fastened display portion made of the ink composition.

  The present invention has been made to solve the above problems, and is an ink composition for an oxygen indicator comprising at least a redox dye, a reducing agent, a binder resin, and a diluent solvent, and the acid value of the binder resin is 50. Is an ink composition for an oxygen indicator characterized by being in the range of from 200 to 200.

  The invention according to claim 2 is the oxygen indicator ink composition according to claim 1, wherein the reducing agent is contained in a ratio of 1 to 100 parts by weight with respect to 1 part by weight of the redox dye. It is characterized by.

  Furthermore, the invention according to claim 3 is the oxygen indicator ink composition according to claim 1 or 2, wherein the binder resin is contained in a ratio of 1 to 100 parts by weight with respect to 1 part by weight of the reducing agent. It is characterized by being.

  Furthermore, the invention according to claim 4 is the ink composition for an oxygen indicator according to any one of claims 1 to 3, wherein the binder resin is either an acrylic resin or a urethane resin. .

  Furthermore, the invention described in claim 5 is characterized in that the oxygen indicator ink composition described in claim 4 contains a carbodiimide-based curing agent as a curing agent.

  Furthermore, the invention described in claim 6 is an oxygen indicator characterized in that a display part made of the ink composition according to any one of claims 1 to 5 is provided on a support.

  Furthermore, the invention described in claim 7 is a packaging member having an oxygen barrier function, and at least a part thereof is provided with a display portion made of the ink composition according to any one of claims 1 to 5. It is the packaging material characterized by this.

  Furthermore, the invention described in claim 8 is a package having an oxygen barrier function and capable of preventing the entry of oxygen from the outside. It is a package characterized by the display part which consists of an ink composition in any one of these being provided.

  The ink composition for an oxygen indicator of the present invention has an indicator function for determining the state of deoxygenation by an oxygen absorbent or the like, and is excellent in dispersion stability and storage stability. In addition, the oxygen indicator, the packaging material, and the packaging body of the present invention having the display portion made of the oxygen indicator ink composition having such characteristics are excellent in the fastness of the display portion.

  As described above, the oxygen indicator ink composition of the present invention contains an oxidation-reduction pigment, and uses the change in hue between its oxidation state and reduction state as a measure for determining the deoxygenation state. And at least a redox dye, a reducing agent, a binder resin, and a diluent solvent.

  Any oxidation-reduction dye can be used as long as it exhibits a different hue in the oxidation state and the reduction state. Specifically, methylene blue, new methylene blue, methylene green, neutral red, indigo carmine, indigo sulfonic acid potassium salt, safranin T, phenosafranine, toluidine blue, capri blue, nile blue, thionine acetate, diphenylamine, diphenylaminesulfonic acid, xylenesia Examples thereof include diol, nitrodiphenylamine, ferroin, nitroferroin, and N-phenylanthranilic acid.

  Any reducing agent can be used as long as it is a compound capable of reducing the above-mentioned redox dye. However, a substance having a too strong reducing ability or a substance decomposed by heat is oxidized in the presence of oxygen. The color or the reduced color after the heat treatment may not be maintained, which is not preferable.

  Particularly preferred as the reducing agent are ascorbic acid and rosemary extract having high acidity. In addition, a compound containing a carboxyl group or a phenolic hydroxyl group can be used as a proton supply source to the redox dye. More specifically, there are tocopherols, polyphenols such as quercetin and anthocyanins, tea catechins, gallic acid derivatives, amino acids such as caffeic acid, ferulic acid and glutathione, and carotenoids such as β-carotene and lycopene. The mixing ratio of the redox dye and the reducing agent is very important, and the amount used is preferably 1 to 100 parts by weight with respect to 1 part by weight of the redox dye. When the ratio of the reducing agent to 1 part by weight of the redox dye is smaller than 1 part by weight, the redox dye does not change from the oxidized color to the reduced color. In order to change color, it is essential to be a redox dye << reducing agent. Further, if the ratio of the reducing agent to 1 part by weight of the redox dye is larger than 100 parts by weight, the ratio of the reactive sites (in this case, carboxyl groups) in the binder resin is deactivated, so that the ink solids are precipitated. It is easy to do and it becomes lacking in stability.

  Of the vehicles for dispersing these redox dyes and reducing agents to impart flowability and the like, the binder resin has an acid value in the range of 50 to 200, preferably 100 to 200. The Such a binder resin has a large number of reactive sites with an acidic substance, and can be stably dissolved in a solvent even when some functional groups are deactivated. That is, by using a binder resin having an acid value in the range of 50 to 200, an ink composition exhibiting dispersion stability and storage stability can be obtained even when a reducing agent having high acidity is added. If the acid value is smaller than this, not only the solubility in a dilute solvent of water / alcohol is deteriorated, but also the ink becomes extremely unstable due to pH shock. As a result, an ink component such as a resin solid content is precipitated, which causes generation of plate clogging or plate fogging during printing, which is not preferable. On the other hand, if the acid value is greater than 200, there is a concern that the water resistance and heat resistance will decrease.

  For example, when the binder resin having a large number of carboxyl groups, that is, a binder resin having a high acid value, is partially deactivated by reaction with a reducing agent, the characteristics as described above are due to the remaining functional groups. It is considered that it can be imparted because it can exist in a dilute solvent in a uniformly stabilized state. Therefore, as the binder resin, an acrylic resin or a urethane resin containing a number of carboxyl groups is preferably used. In addition, the acid value degree in this specification is the mg number of potassium hydroxide required to neutralize the carboxyl group contained in 1 g of binder resin, and shall comply with JIS standards.

  In addition, when it is necessary to consider the solubility of redox dyes, long-term performance guarantee and storage stability, and resistance to heat treatment such as boiling and retort, it is necessary to use a heat-resistant aqueous resin. preferable.

  The carboxyl group contained in the binder resin may be derived from a carboxylic acid such as acrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Moreover, the addition amount of the base added as a neutralizing agent for the carboxyl group is preferably in a range where the neutralization rate of the carboxyl group in the binder resin is from 70% to 120%. When the neutralization rate is too low, the solubility in a diluting solvent and the ability as a protective colloid are lowered, which is not preferable. On the other hand, if the neutralization rate is too high, the binder resin tends to thicken significantly, and printability cannot be obtained.

  When the weight ratio of the reducing agent to the binder resin is set to 1: 1 to 100, an oxygen indicator ink composition excellent in printability and storage stability in addition to dispersion stability can be obtained. If the amount of the reducing agent added is large relative to the binder resin, the resin solids in the ink are aggregated and easily settled. On the other hand, if the addition amount of the reducing agent is small, the redox dye may not be sufficiently reduced.

In addition, an important condition required for the oxygen indicator is that the speed of discoloration indicating a change in the deoxygenation state is fast and that the presence or absence of oxygen can be visually recognized in a short time. Therefore, it is recommended to use an acidic substance that is easy to supply H ⁺ (easily reduces the other dye) as a reducing agent. If the proton releasing ability is high, the reaction from the oxidized form to the reduced form of the redox dye proceeds rapidly. Therefore, it is preferable to employ a substance having a pH of 4.5 or less as the reducing agent. The aforementioned ascorbic acid has a pH of about 2.0, and the rosemary extract has a pH of about 4.2, which can be preferably used as a reducing agent.

  The binder resin is used by being dissolved or dispersed in a diluting solvent such as 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 singly or as a mixture of a plurality of solvents.

  In the ink composition for an oxygen indicator of the present invention, a carbodiimide-based curing agent may be added in order to impart further fastness to the display portion formed thereby. A carbodiimide group reacts with a carboxyl group contained in an acrylic resin or urethane resin to form a crosslinked structure, thereby obtaining an ink coating (display portion) with improved durability.

  In the oxygen indicator ink composition of the present invention, an auxiliary agent such as a surfactant, a dispersant, an antifoaming agent, and a colorant other than the redox dye are added as necessary within a range not inhibiting the function. May be. By adding these to the ink, the storage stability, quick drying, and visibility of the ink can be improved.

  The oxygen indicator ink composition may be a two-component type. That is, it may be a two-component type in which at least liquid A composed of a dye and a binder resin and liquid B composed of at least a reducing agent and a binder resin are mixed and used immediately before printing. Thereby, the storage stability of the ink can be further improved.

FIG. 1 shows a schematic cross-sectional configuration of an oxygen indicator according to the present invention. The oxygen indicator 1 is provided with a display portion 3 made of an oxygen indicator ink composition having the above-described composition and characteristics on a part of a support 2. For the purpose of improving the adhesion strength between the display unit 3 and the support 2 and preventing the redox dye from fading, an anchor coat layer for transmitting oxygen and improving the adhesion to the support, an ultraviolet absorbing material, etc. An overcoat layer or the like may be provided.

  The support 2 may be any material that does not react with the oxygen indicator ink composition and does not inhibit the coloration of the redox dye. Specifically, paper, synthetic paper, non-woven fabric, or synthetic resin film is used.

  In providing the display portion 3 made of the oxygen indicator ink composition on the support 2, printing methods such as letterpress printing method, intaglio printing method, offset printing method, screen printing method, roll coating, spraying, etc. Coating methods such as coating, dip coating, and solid coating are employed.

  On the other hand, FIG. 2 shows a schematic sectional configuration of a packaging material having an oxygen indicator function according to the present invention. The packaging material 11 is a packaging material having an oxygen barrier function, and a display portion 13 made of the ink composition having the above-described composition is provided on at least a part of the packaging base material 12 constituting a part thereof. .

  The packaging substrate 12 has oxygen barrier properties, and is typified by polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyamide 6, polyamide 6-polyamide 66 copolymer, and aromatic polyamide such as MXD6. Polyamide resin, polyacrylonitrile resin, polyvinyl alcohol resin, ethylene-vinyl alcohol copolymer resin, resin film made of polyvinylidene chloride resin, etc., metal foil such as aluminum foil, vapor deposition made of aluminum, silica, alumina, etc. It consists of a thin film layer, a laminated resin film having a vapor deposited thermoplastic resin thin film layer obtained by a CVD vapor deposition method using organosilane such as hexamethylenedisiloxane, acetylene gas, or other carbon gas source. In the figure, reference numeral 14 denotes a gas barrier layer provided on the packaging substrate 11.

  The packaging body of the present invention is a packaging body made of the packaging material as described above, having an oxygen barrier function, and capable of preventing entry of oxygen from the outside, and at least a part of the inside thereof. Are provided with a display portion made of the above-described oxygen indicator ink.

  Hereinafter, the present invention will be described in detail with reference to examples.

By adjusting an ink composition having the following composition as in Procedure 1 below, an ink composition for an oxygen indicator according to Example 1 for comparison was obtained.
<Ink composition 1>
Methylene blue ..... 2.2 parts by weight ascorbic acid ..... 5.5 parts by weight acetal resin ... 41.3 parts by weight isopropyl alcohol ... 17.0 parts by weight water ... 34.0 Part by weight <Procedure 1>
Preparation of reducing agent solution: Dissolve the reducing agent (ascorbic acid) in water.
Adjustment of resin liquid ..... Isopropyl alcohol to resin (acetal resin)
Add and dilute.
Adjustment of the reducing agent / resin solution: The resin solution is added while sufficiently stirring the reducing agent solution.
Ink adjustment .... Pre-adjusted redox dye (methylene blue) water solution
Add the solution to the reducing agent / resin solution.

  Next, on the corona-treated surface of a PET film (thickness 12 μm), use a gravure plate having 200 L, 30 μm cells, print the ink of the above composition twice in a pattern, and dry at room temperature for 12 hours. A display unit was provided. Thereafter, a sealant film is formed on the display portion forming side of the PET film, an alumina vapor-deposited film is dry-laminated on the other side, and a urethane-based two-component curable adhesive is dry-laminated. Such packaging material was obtained.

  And the packaging bag which concerns on Example 1 for a comparison was produced using the packaging material so that the display part which consists of an ink composition might be located inside. This packaging bag was filled with an oxygen absorbent and then purged with nitrogen and sealed.

An ink composition for an oxygen indicator according to Example 2 for comparison was obtained by adjusting an ink composition having the following composition as in Procedure 2 below.
<Ink composition 2>
Methylene blue ..... 2.2 parts by weight Ascorbic acid ..... 5.5 parts by weight aqueous acrylic resin A ... 35.8 parts by weight isopropyl alcohol 17.0 parts by weight water 34.0 Part by weight Tertiary amine: 0.5 part by weight Carbodiimide type curing agent: 5.0 parts by weight (Aqueous acrylic resin A The acid value is 35.)
<Procedure 2>
Preparation of reducing agent solution: Dissolve the reducing agent (ascorbic acid) in water.
Adjustment of resin liquid ..... Isopropyl alcohol to water-based resin (water-based acrylic resin A)
Add and dilute.
Adjustment of the reducing agent / resin solution: While thoroughly stirring the reducing agent solution, add the resin solution, and
Tertiary amine: dimethylaminoethanol with thorough stirring
Add
Ink adjustment .... Pre-adjusted redox dye (methylene blue) water solution
Add the solution to the reducing agent / resin solution.

                          A carbodiimide curing agent is added immediately before printing.

  Using the ink composition according to Example 2 for comparison that was adjusted in this manner, and the other conditions were the same as in Example 1, the packaging material and package according to Example 2 for comparison were obtained. It was.

The ink composition for the oxygen indicator of the present invention according to Example 3 was obtained by adjusting an ink composition having the following composition as in Procedure 2 above.
<Ink composition 3>
Methylene blue ............ 2.2 parts by weight ascorbic acid ............ 5.5 parts by weight aqueous acrylic resin B ... 35.8 parts by weight isopropyl alcohol 17.0 parts by weight water 34.0 Part by weight tertiary amine ············ 0.5 parts by weight Carbodiimide type curing agent ··· 5.0 parts by weight (Water-based acrylic resin B The acid value is 120.)
Thus, the ink composition which concerns on Example 3 prepared in this way was used, and others were the same conditions as Example 1, and the packaging material and package of this invention which concern on Example 3 were obtained.

By adjusting an ink composition having the following composition as in Procedure 1 above, an ink composition for an oxygen indicator according to Example 4 for comparison was obtained.
<Ink composition 4>
Methylene blue ............ 2.2 parts by weight rosemary extract ...... 4.4 parts by weight acetal resin ............ · · · 42.4 parts by weight isopropyl alcohol ················· 17.0 parts by weight water ············································································ 34.0 Part by weight Using the ink composition according to Example 4 for comparison prepared as described above, and the packaging material and the package according to Example 4 for comparison under the same conditions as in Example 1 except for the above. Got.

By adjusting an ink composition having the following composition as in Procedure 2 above, an ink composition for an oxygen indicator according to Example 5 for comparison was obtained.
<Ink composition 5>
Methylene blue ............ 2.2 parts by weight Rosemary extract ...... 4.4 parts by weight aqueous acrylic resin A ... 36.9 parts by weight isopropyl alcohol 17.0 parts by weight water 34.0 Part by weight Tertiary amine: 0.5 part by weight Carbodiimide type curing agent: 5.0 parts by weight (Aqueous acrylic resin A The acid value is 35.)
Using the ink composition according to Example 5 for comparison prepared in this manner, and the other conditions were the same as in Example 1, the packaging material and package according to Example 5 for comparison were obtained. It was.

The ink composition for the oxygen indicator of the present invention according to Example 6 was obtained by adjusting an ink composition having the following composition as described in Procedure 2 above.
<Ink composition 6>
Methylene blue ... 2.2 parts by weight Rosemary extract ... 4.4 parts by weight aqueous acrylic resin B ... 36.9 parts by weight isopropyl alcohol 17.0 parts by weight water 34.0 Part by weight tertiary amine ············ 0.5 parts by weight Carbodiimide type curing agent ··· 5.0 parts by weight (Water-based acrylic resin B The acid value is 120.)
Using the thus-prepared oxygen indicator ink composition of the present invention according to Example 6 and the other conditions similar to those of Example 1, the packaging material and package of the present invention according to Example 6 were used. Obtained.

Next, stability evaluation and a storage test were performed on the ink composition according to each example, and a heat resistance test was performed on the package.
<Evaluation of stability>
The ink composition was allowed to stand for 1 week, and the dispersion stability of the ink composition was visually observed. The results are shown in Table 1.
<Storage test>
A small piece of packaging material according to each example is placed in an environmental test room at 25 ° C./40° C./60° C. and stored for 6 months. Thereafter, the appearance and color change are visually observed to evaluate the storage stability. went. The results are shown in Table 2.
<Heat resistance test>
The package according to each example was subjected to a retort treatment at 121 ° C. for 30 minutes, and changes in appearance and color tone of the oxygen indicator (display unit) were visually observed. The results are shown in Table 3.

表１からも分かるように、実施例２および実施例５に係るインキ組成物は、酸性度の高い還元剤との相互作用により、樹脂固形分が沈澱するため、グラビア印刷可能なインキを調整できなかった。

As can be seen from Table 1, the ink compositions according to Example 2 and Example 5 can adjust the gravure printable ink because the resin solids precipitate due to the interaction with the reducing agent having high acidity. There wasn't.

  In addition, as can be seen from Table 2, the packaging materials according to Example 1 and Example 4 are at 40 ° C. and 60 ° C. because the binder resin of the ink composition constituting the display unit does not have heat resistance. In the long-term storage, bleeding occurred in the outline of the display part (print coating part).

  Further, as can be seen from Table 3, the package according to Example 1 is heat-treated because the reducing agent (ascorbic acid) in the ink composition constituting the display unit located inside does not have heat resistance. It was later deactivated and the reduced color could not be maintained. Moreover, since the binder resin in the ink composition which comprises the display part does not have heat resistance, the package which concerns on Example 1 and Example 4 has the outline of a display part (print coating part) after heat processing. Bleeding was confirmed.

It is explanatory drawing which shows the general | schematic cross-section structure of the oxygen indicator which concerns on this invention. It is explanatory drawing which shows the general | schematic cross-section structure of the packaging material which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Oxygen indicator 2 ... Support body 3 ... Display part 11 ... Packaging material 12 ... Packaging base material 13 ... Display part 14 ... Gas barrier layer

Claims (8)

  An oxygen indicator ink composition comprising at least a redox dye, a reducing agent, a binder resin, and a diluting solvent, wherein the binder resin has an acid value in the range of 50 to 200. .   The ink composition for an oxygen indicator according to claim 1, wherein the reducing agent is contained in a ratio of 1 to 100 parts by weight with respect to 1 part by weight of the redox dye.   3. The oxygen indicator ink composition according to claim 1, wherein the binder resin is contained in an amount of 1 to 100 parts by weight with respect to 1 part by weight of the reducing agent.   The ink composition for an oxygen indicator according to any one of claims 1 to 3, wherein the binder resin is either an acrylic resin or a urethane resin.   The ink composition for an oxygen indicator according to claim 4, further comprising a carbodiimide-based curing agent as a curing agent.   An oxygen indicator, wherein a display unit comprising the ink composition according to claim 1 is provided on a support.   A packaging material having an oxygen barrier function, wherein a display part made of the ink composition according to any one of claims 1 to 5 is provided on at least a part thereof.   A packaging body having an oxygen barrier function and capable of preventing entry of oxygen from the outside, comprising at least a part of the inner side of the ink composition according to any one of claims 1 to 5. A package comprising a display portion.

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