JP2008069278A - Ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition which can detect existence of oxygen largely affecting to deterioration of a content in a vessel or a bag and grasp an oxygen gas in the vessel or the bag at a glance using a means such as discoloration. <P>SOLUTION: The ink composition comprising an oxidation-reduction pigment, a volatile reducing agent, a non-volatile reducing agent, an alkaline substance, a binder and a solvent is used. As the oxidation-reduction pigment, a thiazine-based pigment, an oxaline-based pigment, a lactone-based pigment, a sultone-based pigment, an azo-based pigment, an indigoid-based pigment, an anthraquinone-based pigment, a triphenylmethane-based pigment or the like can be used. Further, as the oxidation-reduction pigment, methylene blue, thionine, brilliant blue, fast green, indigocarmine, amino black or the like can be used. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink composition capable of detecting environmental changes and grasping environmental changes in a container or bag at a glance by using a means of discoloration. In particular, the present invention relates to an oxygen-detecting ink composition that can detect the presence of oxygen and grasp the presence or absence of oxygen gas in a container or bag at a glance by using a means of discoloration.

  In addition to the conventional form of purchasing ingredients at supermarkets and cooking and eating the purchased ingredients at each home, recently there is no time for cooking due to co-working, or more time for your hobbies Therefore, with the intention of performing housework easily, with regard to cooking, there are increasing forms of purchasing cooked foods cooked in a backyard such as a supermarket or a central kitchen and eating them at home.

  On the other hand, for cooked foods at supermarkets and convenience stores, products are being developed actively to suit the taste, quantity, etc. of individual foods while selling the convenience of cooked foods, and many types of foods are put on the market. Has been. In addition, side dish sellers such as supermarkets and convenience stores provide delicious foods with reduced food preservatives, etc. in order to provide the deliciousness of the ingredients themselves, which is a strong consumer demand, and to be safe, secure, and healthy. Looking for. However, when food preservatives are reduced, food starts to rot faster, so food safety measures are essential. As a method for preventing food from decaying, the influence of oxygen in the air is important for food decay. Therefore, various methods for packaging the package in an oxygen-free state have been studied.

  As a packaging method to keep the package in an oxygen-free state for the purpose of preventing food spoilage, vacuum packaging in which the package is vacuumed, oxygen-free packaging and packaging in which the package is oxygenated using an oxygen scavenger Examples include gas replacement packaging that seals the inside of the body with a desired gas.

  For example, in the case of vacuum packaging, the packaging body is kept in a vacuum state, so that it is possible to prevent the oxidation of foods due to oxygen and to determine whether the packaging body is kept in a vacuum. By visually checking whether there is an inflow, it can be determined relatively easily. Further, it is advantageous in terms of storage and display space, and is often used when relatively long-term storage is required. However, since the inside of the package is evacuated, the film or the like that packages the package by atmospheric pressure is in a packaging form that is in close contact with the food, cannot give a sense of volume, and the form of the food becomes distorted Therefore, a problem remains in terms of cosmetics.

On the other hand, oxygen-free packaging that uses an oxygen scavenger in the package, or packaging with a packaging material having an oxygen absorbing layer, and gas replacement packaging that seals the package with a desired gas, without crushing food by atmospheric pressure, Since the food can be displayed as it is, it is excellent in that the product can be differentiated by a so-called display effect such as making the product look delicious. For this reason, for relatively short-term products with a shelf life of several days to one month, studies are being made mainly on oxygen-free packaging and gas replacement packaging using an oxygen absorbent.
However, in oxygen-free packaging that uses an oxygen scavenger in the package, and gas replacement packaging that seals the package with the desired gas, visually determine whether the package is stored in a suitable gas atmosphere. It is difficult to do this, and a method for determining whether the gas atmosphere in the package is appropriate is being sought. In particular, the development of oxygen detection for detecting the presence or absence of oxygen that has a significant effect on food spoilage, and packaging containers and bags equipped with such oxygen detection are desired.

  As such an oxygen detection function, an oxygen scavenger with an oxygen detection function is disclosed. For example, Patent Document 1 discloses a deoxygenating agent with oxygen detection, which comprises methylene blue, saccharides, an alkaline substance, moisture, and ascorbic acid. This oxygen scavenger is deoxygenated by ascorbic acid, but in addition to the deoxygenation function, which is the original function, methylene blue is used as an indicator dye. When methylene blue contains oxygen, it shows blue, and when there is no oxygen, it shows no color. Because it has a detection function, it is excellent in that it can check the presence or absence of oxygen at a glance.

  However, the oxygen detection component disclosed in Patent Document 1 has poor durability such as light resistance and heat resistance. Further, the storage of the oxygen detection component needs to be in a cool and dark place, and in most cases, temperature management of a refrigerator or the like is necessary. In addition, even when stored in a cool and dark place, the product life of the oxygen detection component is a maximum of 2 to 3 months, and it is difficult to continue the long-term oxygen detection function. It takes a lot of time to manage the merchandise that has been added. In addition, since the oxygen detection component disclosed in Patent Document 1 has poor durability such as light resistance and heat resistance, the oxygen detection composition is applied to a film or the like to create a base material having an oxygen detection function. In this case, since the maintenance period in the above-mentioned cold and dark place and the oxygen detection function is short, it is difficult to use as a product, and because it has poor heat resistance, it can be used as a base material for laminating and bag making. There is a problem that is difficult.

Japanese Patent Laid-Open No. 54-138489

  An object of the present invention is to provide an ink composition capable of reversibly detecting environmental changes and having light resistance and heat resistance.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have made the present invention.
That is, the present invention is as follows.
(1) An ink composition comprising a redox dye, a volatile reducing agent, a nonvolatile reducing agent, an alkaline substance, a binder and a solvent.
(2) The ink composition according to (1), wherein the binder contains a cyclohexanone ketone resin or an acetophenone ketone resin.

(3) The redox dye is at least one selected from the group consisting of thiazine dyes, oxalin dyes, lactone dyes, sultone dyes, azo dyes, indigoid dyes, anthraquinone dyes, and triphenylmethane dyes. The ink composition according to (1), wherein the ink composition is one dye.
(4) The ink composition according to any one of (1) to (3), wherein the oxidation-reduction potential of the oxidation-reduction dye is +0.1 V or more and +1.5 V or less.
(5) The redox dye is at least one dye selected from the group consisting of methylene blue, thionine, brilliant blue, first green, indigo carmine, and amino black, any one of (1) to (4) An ink composition according to any one of the above.

(6) Any one of (1) to (5), wherein the volatile reducing agent is at least one reducing agent selected from the group consisting of ammonia, thiols, aldehydes, and low molecular amines. The ink composition described in 1.
(7) The non-volatile reducing agent is at least one reducing agent selected from the group consisting of reducing sugars, ascorbic acid, cysteine, and aldehydes, according to any one of (1) to (6), Ink composition.
(8) The ink according to any one of (1) to (7), wherein the alkaline substance comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, and sodium bicarbonate. Composition.

(9) A detection substrate coated with the ink composition according to any one of (1) to (8).
(10) An original fabric comprising the detection substrate according to (9).
(11) A container produced using the detection substrate according to (9) or the original fabric according to (10).
(12) A bag produced using the detection base material according to (9) or the original fabric according to (10).

  Since the ink composition of the present invention is excellent in durability such as light resistance and heat resistance, when the ink composition of the present invention is used as an oxygen detection ink, the substrate coated with the ink composition is used as a detection substrate. The detection substrate can be used as a raw material for laminating or bag making, and a packaging container, a packaging film, a bag, or the like can be produced. In addition, the ink composition used for the detection substrate of the present invention has alcohol resistance in addition to the above-described durability such as light resistance and heat resistance, and gas replacement using bacteriostatic and sterilizing gas such as alcohol It can also be used in packages and contents containing alcohol. Further, when the detection base material of the present invention is used in an oxygen scavenger outer bag, the oxygen scavenger using the detection base material is excellent in durability such as light resistance and heat resistance, and thus disclosed in the prior art. In addition to the need for storage and management in such a special environment, the oxygen detection function can be integrated with the oxygen scavenger in advance. Furthermore, since there is no durability in the prior art, it is necessary to stick an oxygen sensing member that has been subjected to adhesive processing when putting the oxygen scavenger into the package, and trouble and trouble in this process can be saved. . Therefore, it is possible to find a possibility that all oxygen scavengers that were impossible with the prior art have an oxygen detecting function, and a container or bag for storing the oxygen scavenger with the oxygen detecting function, and a detection base material. Is used for containers and bags, the containers and bags themselves can be provided with an oxygen detection function, and all products can be inspected for oxygen leaks.

Hereinafter, the present invention will be specifically described.
The ink composition of the present invention comprises a redox dye, a volatile reducing agent, a non-volatile reducing agent, an alkaline substance, a binder, and a solvent. The redox dye changes depending on the environmental state of the reduced state and the oxidized state. Changes in the environment can be detected. For example, redox dyes that can detect changes in color in the visible light region include methylene blue. In the case of methylene blue, colorless is shown in the reduced state, blue is shown in the oxidized state, and the environment changes due to a color change of colorless-blue. Can be detected.

The ink composition of the present invention will be described in detail.
The binder used in the present invention mainly includes the redox dye in a dispersed state in the binder and plays a role of fixing to the adherend surface. The substance used for the binder may be either a single substance or a mixture thereof as long as it is a publicly known binder. Further, in the case of gravure printing, the binder content in the ink composition of the present invention may be 10 to 60% by weight based on the entire ink composition from the viewpoint of the viscosity of the ink composition and the coating film formability of the printed material. Preferably, it is 15 to 55% by weight. The surface to be adhered may be subjected to a known surface treatment such as corona treatment to improve the binding property.

In addition, in the case of inkjet on a plastic surface, from the viewpoint of binding to the plastic, which is the adherend surface, and from the viewpoint of ejection performance of the ink composition from the print head and clogging of the nozzle holes, the entire ink composition The content is preferably 10 to 60% by weight, more preferably 15 to 55% by weight. The surface to be adhered may be subjected to a known surface treatment such as corona treatment to improve the binding property. In the printing by the inkjet technique, the viscosity of the ink composition is preferably 3 to 150 mPa · s as a viscosity at 30 ° C., and more preferably 10 to 40 mPa · s from the viewpoint of clear printing. In order to realize this solution viscosity, it is preferable that the weight average molecular weight (Mw) of the binder is small, but in view of elution of the binder component, the weight average molecular weight is preferably 1000 to 8000, and more preferably the weight average molecular weight is 1500. -7000, more preferably the weight average molecular weight is 2000-6000.
In addition, the viscosity of the ink composition preferable in gravure printing is preferably 20 to 600 mPa · s as a viscosity at 30 ° C., and more preferably 30 to 400 mPa · s from the viewpoint of clear printing. The average molecular weight and binder concentration can be adjusted.

  Examples of binders used in the present invention include, in addition to ketone resins, cellulose derivatives (cellulose esters such as nitrocellulose, cellulose ethers such as hydroxyethyl cellulose, modified celluloses such as oxycellulose), polyvinyl alcohol, polyols, polyvinyl Examples thereof include pyrrolidone, polyamide-based, polyacetal-based, and other natural resin-based binders and modified products thereof. These binders can be used alone or in combination according to the surface material of the printed material or coated material. Preferred binders are ketone resins from the viewpoint of the pigment reduction assisting function, cellulose derivatives and natural resins are preferable from the viewpoint of color change reactivity of the pigments, and natural resins from the viewpoint of safety. As a comprehensive combination of these, ketone resin and natural resin are preferable. Further, when the printing surface is plastic, it is preferable that the concentration of the binder is 10% by weight or more in order to form a uniform surface on the printing part. However, the use of the binder containing a ketone resin reduces the above low viscosity. And the binder concentration are more preferable. Further, when a binder containing a ketone resin is used, the dye can be reduced to a leuco state with a small amount of a non-volatile reducing agent, and the pH of the ink solution can be set to 10 or less, so that the storage stability of the ink composition can be reduced. In addition, the light resistance of the printed matter is excellent.

A ketone resin is a substance obtained by a condensation reaction between a compound having a ketone group and an aldehyde, and there are resins such as methyl ethyl ketone, methyl isobutyl ketone, methyl cyclohexanone, cyclohexanone, and acetophenone, which are appropriately selected and used. be able to. Preferred are cyclohexanone-based and acetophenone-based resins. Examples of the cyclohexanone-based ketone resin include a ketone resin composed of cyclohexanenone and formaldehyde. Examples of the acetophenone-based ketone resin include a ketone resin composed of acetophenone and formaldehyde. Moreover, you may use these substances individually or in mixture of 2 or more types.
The addition amount of the ketone resin to the ink composition is preferably 10% by weight or more, more preferably 15% by weight or more from the viewpoint of the binder function and the reduction function of the redox dye.

  When a resin having a slow oxygen permeability such as a ketone resin is used as the binder, an existing binder having a good oxygen permeability may be mixed from the viewpoint of controlling the coloring rate of the redox dye. Usually, ketone resins have a low oxygen permeability due to intramolecular and intermolecular hydrogen bonds. When the ink composition of the present invention is used for oxygen detection, the coloring of the redox dye is due to the reaction with oxygen diffusing in the binder, and the binder is used to immediately detect changes in the environment in the package. For the purpose of improving the oxygen diffusibility, it is preferable to mix and use a binder or resin having excellent oxygen permeability. Examples of the binder to be mixed include the above-mentioned cellulose derivatives and natural resin binders and modified products thereof from the viewpoint of improving the binder functionality and oxygen diffusibility in the binder. In addition, polylactic acid, polyethylene resin, and the like Is mentioned. In particular, natural resin-based shellac resins are preferred from the viewpoints of compatibility with solvents, ink viscosity, and food safety. The shellac resin is an ester compound of a resin acid and an alcohol, and more preferably an ester compound in which the resin acid contains alleuritic acid, jarlaric acid, or laxillaral acid.

In the ink composition of the present invention, when the binder is contained in an amount of 10% by weight or more, it can be applied to a substrate having high oxygen permeability. Originally, a film having low oxygen permeability as a base film has a structure having a polar functional group such as a hydroxyl group or a ketone group in a polymer chain constituting the film, and the functional groups are hydrogenated. By improving the packing between molecules such as bonds, the oxygen permeability is lowered. However, even in the application such as printing and coating, this polar functional group is the function of chemical substances such as dyes and binders in the ink. By interacting with the group, a stable bond is likely to be formed, and so-called ink printing suitability tends to be high. The ink composition of the present invention uses a ketone resin as a binder, and when the binder concentration is 10% by weight or more, the coated surface is stable even on a substrate with high oxygen permeability, which originally tends to have low ink printability. It is possible to perform coating that is difficult to peel off from the substrate. Usually, when printing or coating is performed on a film having high oxygen permeability, it is necessary to perform surface treatment such as corona treatment, and generally requires a surface energy of 38 mN / m or more.
In the present specification, for convenience, a substrate having a thickness of 100 μm or more is referred to as a sheet, and a substrate having a thickness of less than 100 μm is referred to as a film.
The oxygen detection ink of the present invention can form a stable film such as printing or coating even on a substrate (film or sheet) having a high oxygen permeability and a relatively small number of polar functional groups. When applying the ink composition of this invention to a base material, you may give a corona treatment etc. as needed. It is preferable that the surface energy of the substrate (film or sheet) is high from the viewpoint of ease of application of the ink composition, but there is a limit to the post-treatment surface treatment technology such as corona treatment, and usually Up to 44 mN / m. Preferably it is 32 mN / m or more, More preferably, it is 34 mN / m, More preferably, it is 36 mN / m.

Next, the redox dye used in the present invention will be described.
The color change referred to in the present invention is a reaction of changing the light absorption wavelength of the redox dye, and the light absorption wavelength is caused by the structural change of the redox dye itself or the reaction of the redox dye with another compound contained in the oxygen detector. That changes. In addition, by selecting various redox dyes to be used in the present invention, it is possible to detect the presence or absence of oxygen using a desired color and a desired oxygen concentration as a threshold, and further setting the oxygen concentration to be detected, the color change rate, etc. Can be set to a desired setting. Furthermore, it is preferable that the color change by the redox dye is in the visible light range (400 nm to 600 nm), since it can be visually confirmed at a glance without using a wavelength measuring machine. Furthermore, when a mixture of several redox dyes is chemically stable and the reaction is independent, for example, the oxygen concentration necessary for the reaction of the redox dye, the reaction rate, and the color during the reaction. If you use a mixture of several different redox dyes, the color can be changed stepwise depending on the oxygen concentration, such as orange at a certain oxygen concentration and blue when the oxygen concentration is high, or the oxygen concentration It is possible to change the color stepwise depending on the oxygen exposure time such as brown when the exposure time is short, and red when the oxygen concentration exposure time is long.

  The redox dye as used in the present invention refers to a dye that changes color due to environmental changes such as pH, temperature, transfer of hydrogen and electrons, or redox by direct oxidation with oxygen. The redox dye may be any substance as long as the light absorption wavelength is changed by oxidation or reduction of the substance. The presence or absence of oxygen can be determined by detecting the light absorption wavelength thus changed. The wavelength range of the light absorption wavelength that can be used can be any wavelength as long as the changed wavelength can be measured or detected.

  Examples of the redox dye in the present invention include thiazines, oxalins, lactones, sultones, azos, indigoids, anthraquinones, triphenylmethanes, phenanthroline derivatives, and mixtures thereof, more preferably Thiazine, oxalin, lactone, sultone, indigoid, anthraquinone, triphenylmethane and mixtures thereof. Specifically, indigotetrasulfonic acid, diphenylamine, diphenylbenzidine, diphenylaminesulfonic acid, ferroin, nitroferroin, methylferroin, dimethylferroin, methylene blue, galocyanine, methyl red, methyl bio red, thymol blue, anthocyanin, methyl Yellow, phenol red, thymolphthalein, azaline yellow, anthraquinone, safranine, phenosafranine, β-carotene, lycopene, resorufin, thionine, cresyl blue, toluidine blue, methyl orange, litmus, bromthymol blue, carmine, phenolphthalene, brilliant Blue, first green, indigo carmine, amino black, 1,10-phenanthroline, 1,7-phenane Lorin, 5-phenyl, 1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, N-phenylanthrolinic acid, Nile blue, natural red, diphenylamine-4-sulfonic acid, 2,2′-dipyridine 2,6-dichloroindophenol, 3,3′-dimethylnaphthidine, N, N-dimethyl-1,4-phenylene-diammonium, diphenylamine, diphenylbenzazine and the like. Preferably, indigotetrasulfonic acid, diphenylamine, diphenylbenzidine, diphenylaminesulfonic acid, ferroin, nitroferroin, methylferroin, dimethylferroin, methylene blue, galocyanine, methyl red, methyl bio red, thymol blue, anthocyanin, methyl yellow, Phenol red, thymolphthalein, azaline yellow, safranin, phenosafranine, resorufin, thionine, toluidine blue, methyl orange, litmus, bromthymol blue, brilliant blue, first green, indigo carmine, amino black, 2,6-dichloroindophenol More preferably, indigo tetrasulfonic acid, diphenylamine sulfonic acid, ferroin, nitrophenol Loin, methylferroin, dimethylferroin, methylene blue, methyl bio red, thymol blue, anthocyanin, phenol red, thymolphthalein, azaline yellow, safranine, phenosafranine, resorufin, thionine, toluidine blue, methyl orange, litmus, bromthymol Blue, brilliant blue, first green, indigo carmine, amino black, 2,6-dichloroindophenol, more preferably indigo tetrasulfonic acid, diphenylamine sulfonic acid, ferroin, nitroferroin, methylferroin, dimethylferroin, Methylene blue, thymol blue, thymolphthalein, safranine, phenosafranine, thionine, toluidine blue, litmus, buoy Whip mall blue, brilliant blue, Fast Green, a 2,6-dichloro indophenol. Even more preferred are food colors such as brilliant blue, first green, indigo carmine, amino black and the like.

The addition amount of the redox dye to the ink composition is usually preferably 0.1 to 5% by weight of the ink composition, more preferably 0.3 to 4 from the viewpoint of solubility in a solvent and color difference discrimination. % By weight, more preferably 0.3 to 3% by weight.
When the redox dye used in the present invention has a specific redox potential, the oxygen content in the package can be detected at a desired concentration by using redox dyes having different redox potentials. The value measured by the cyclic voltammetry described later is used as the oxidation-reduction potential in the present invention. When the oxidation-reduction potential is +0.1 V or more and less than +0.7 V, the redox dye is reduced by a volatile reducing agent. In this state, since it is immediately changed to an oxidized state by a very small amount of oxygen, the presence or absence of a very small amount of oxygen can be detected. In addition, when the oxidation-reduction potential is less than +0.1 V, the color before color development due to oxygen exposure can be arbitrarily colored, so that an effect of visually conspicuous color development due to oxygen exposure can be achieved. Further, when the oxidation-reduction potential is +0.7 V or more, it can be used as oxygen detection even when an oxygen scavenging material such as an oxygen scavenger is not present in the package, and depending on the value of the oxidation-reduction potential, The oxygen content can be detected at a desired concentration, and the dye of the ink composition for oxygen detection that changes color at a desired oxygen content according to the value of the redox potential can be achieved.
A redox potential of less than +0.1 V is suitable when a sensitive reaction rate for oxygen is desired. +0.1 or more and less than +0.7 V is suitable for the case where there is no reaction even when there is a small amount of oxygen (oxygen concentration is less than 0.5%) and the color changes at an oxygen concentration higher than that.
+0.7 V or more is suitable when the oxygen concentration is 0.5% or more. A preferable redox potential is +0.1 or more and +1.5 V or less.

  The volatile reducing agent referred to in the present invention plays a role in bringing the redox dye in a reduced state (leuco state) in an initial stage such as a process of applying an ink composition to a substrate, a laminating process or a bag making process. The non-volatile reducing agent consumed when showing reversibility can be preserved. In addition, the redox dye can be stably stored in the leuco state, and can quickly shift to the leuco state. Further, after consumption of the volatile reducing agent, the remaining volatile reducing agent scatters and is excluded from the system of the oxygen detection part. Therefore, after consumption of the volatile reducing agent, the detection substrate of the present invention is a normal substrate. It can be handled in the same way as a reversible oxygen detector. Furthermore, by increasing or decreasing the content of the volatile reducing agent in the oxygen detection ink composition, the delay time from when the redox dye in the reduced state comes into contact with oxygen to color development can be adjusted. The volatile reducing agent preferably has a vapor pressure at 20 ° C. of 1 hPa or more, more preferably 5 hPa or more. Specific examples of the volatile reducing agent used in the present invention include ammonia, thiols, aldehydes, and low-molecular amines, preferably ammonia. Moreover, you may use these substances individually or in mixture of 2 or more types.

  The addition amount of the volatile reducing agent is preferably from 0.1 to 20% by weight of the ink composition, more preferably from 0.3 to 15% by weight, still more preferably from the viewpoint of reducing ability in the ink composition. 3 to 13% by weight. In addition, when the volatile reducing agent is ammonia, a combination using a ketone resin as the binder is preferable from the viewpoint of the reactivity of the decolorization reaction that turns the redox dye into a leuco state. Furthermore, the pH of the ink composition can be adjusted by appropriately adjusting the content ratio of ammonia as a volatile reducing agent and ketone resin as a binder, making full use of the phase transition function of the binder when forming a coating film. Thus, the coated surface can be controlled to be transparent or opaque. Furthermore, by using ammonia as a volatile reducing agent and a ketone resin as a binder and appropriately adjusting the content ratio, the conventional ink composition reduces the pigment at a pH of 10.5 or more. On the other hand, the dye reduction can be performed on the neutral side (pH of about 10 or less) from the value of the prior art, and thus the light resistance function can be remarkably improved.

  The non-volatile reducing agent referred to in the present invention mainly serves to make the dye colorless when showing reversibility upon detection. In addition, like the volatile reducing agent, the redox dye is stable in storage in the leuco state and plays a role of maintaining the leuco state. Nonvolatile reducing agents used in the present invention include ascorbic acid, erythorbic acid and salts thereof, ascorbate, D-arabinose, D-erythrose, D-galactose, D-xylose, D-glucose, D-mannose, D -Reducing sugars such as fructose and D-lactose, metal salts such as stannous salts and ferrous salts, aldehydes, cysteine and the like can be used, and reducing sugars, ascorbic acid, cysteine and aldehydes are preferred. Moreover, you may use these substances individually or in mixture of 2 or more types. Since the amount of the non-volatile reducing agent used in the present invention varies depending on the type of solvent, for example, when an alcohol-based solvent is used, there is a limit to the amount of reducing sugar that can be dissolved, and a mixed solvent such as alcohol and water can be used. It may be better to use it. The addition amount of the non-volatile reducing agent is preferably from 0.1 to 20% by weight, more preferably from 0.3 to 15% by weight, and still more preferably from the viewpoint of reducing ability and reversibility of discoloration. 0.5 to 10% by weight.

The alkaline substance as used in the present invention is a substance that creates an alkaline environment that exhibits reversibility. For example, an alkali metal or alkaline earth metal hydroxide, carbonate, bicarbonate, phosphate, boric acid Examples thereof include water-soluble compounds such as salts, which may be hydrated or anhydrous. More specifically, for example, sodium borate, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, lithium hydroxide, potassium phosphate, barium hydroxide, magnesium hydroxide, potassium phosphate, etc. Preferably, sodium hydroxide, potassium hydroxide, and sodium hydrogen carbonate are used. Moreover, you may use these substances individually or in mixture of 2 or more types. From the viewpoint of the alkaline environment of the ink solution and the discoloration environment of the redox dye, the alkaline substance is preferably added so that the pH of the ink composition is 3 to 10.5. More preferably, the ink composition should be added so that the pH of the ink composition is 3.5 to 10.3, more preferably 4.5 to 10.
The amount to be added varies depending on the basic strength of the alkaline substance, but in the case of sodium hydroxide, it is preferably 0.3 to 15% by weight, more preferably 0.5 to 12% by weight of the ink solution.

The solvent as used in the present invention plays a role of making the oxygen detection ink composition uniform. Specific examples of the solvent include alcohols, ketones, esters, water, and the like, and a single composition or a mixed composition of these solvents can be used as the solvent. Preferably, a volatile solvent is preferable from the viewpoint of a drying system at the time of application.
More preferred are alcohols from the viewpoint of safety, and examples thereof include ethanol, propanol, isopropanol (IPA), butanol and the like. In particular, when the volatile reducing agent is ammonia, a solvent using water is preferable from the viewpoint of use in aqueous ammonia and the solubility of the dye, and water and alcohol are preferable from the viewpoint of binder solubility and drying during printing. The mixture of is more preferable.
The solvent varies depending on conditions such as the solubility of the substances constituting the ink composition and the drying time. In the case of isopropanol (IPA), it is preferably 35 to 85% by weight, more preferably 40 to 80% by weight of the ink composition. is there.

The ink composition used in the present invention may contain a commonly used pH buffer, humectants such as polyethylene glycol, glycerin, propylene glycol, sorbitol and erythritol, oxygen scavengers, and the like.
The ink composition of the present invention can be applied to a sheet or film to produce a detection substrate capable of detecting environmental changes. The detection base material can be used as a raw material for processing such as a laminate, and can be laminated with another base material, or can be processed into a container and a bag using the raw material.

  The oxygen detection in the present invention means detecting the presence or absence of oxygen using a specific oxygen concentration as a threshold value. The oxygen detector is formed by applying an ink composition comprising a redox dye, a volatile reducing agent, a non-volatile reducing agent, an alkaline substance, a binder, and a solvent to a sheet or film. It has the function of causing the presence or absence of oxygen. A known technique can be used for the coating method. For example, a spray method in which the ink composition is sprayed into small droplets, a bar coating method using a Mayer bar, etc., printing such as gravure, flexo, screen, and ink jet. As for the application shape, solid printing, character printing, pattern printing, dot printing or the like may be performed on one or both sides of the substrate. Preferably, pattern printing or dot printing is preferable because it is cut by post-processing or bag-making.

The base material as used in the present invention refers to a sheet-like flat plate of resin, paper, metal (including metal foil), etc., and the detection base is obtained by applying the ink composition of the present invention to the base material. It can be a material. In addition, the detection substrate coated with the ink composition of the present invention is bonded to another substrate as a raw fabric, and the detection substrate is directly subjected to molding processing, bag-making processing, or other substrate. The original fabric bonded to a material or the like can be processed into a container or a bag from the detection base material or the original fabric by molding or bag making.
Examples of the substrate include a single layer or a multilayer configuration composed of resin, paper, and metal (including metal foil), but there is no problem as long as the ink composition can be applied in a planar shape. When the contents are processed foods such as side dishes and lunch boxes, and the container or bag is heated as it is by a microwave oven, the outermost layer of the base material is used from the viewpoint of preventing sparks due to collision of electrons in the microwave oven. A material containing no metal is preferred. From the viewpoint of separation at the time of disposal, a resin made of the same material as the container or bag is more preferable. In addition, at least one substrate constituting the raw fabric is preferably transparent in order to confirm the color of the ink composition. The thickness of the substrate of the present invention is only required to be able to apply the ink composition of the present invention. From the viewpoint of stable application, the thickness of the substrate is preferably 2 μm to 5 mm, more preferably 7 μm to 3 mm, and further Preferably it is 10 micrometers-1 mm.

  If the resin used for the base material as used in the present invention is a resin used for food packaging, there is no problem. For example, polyolefin resins (PO) including polyethylene resins (HDPE, LLDPE, etc.), polypropylene resins (PP), polybutene-1 resins (PB), poly-4-methylpentene-1 resins, or Modified polyolefin resin (PO) including ethylene-vinyl acetate copolymer resin (EVA), ethylene-methyl methacrylate copolymer resin (EMA, etc.), ethylene-vinyl alcohol copolymer resin (EVOH, etc.) Modified products), polyethylene terephthalate-based (modified) resins (PET, etc.), polybutylene terephthalate-based (modified) resins (such as PBT) and some other aromatic components, or polylactic acid-based resins, polyglycols Polyester resin (PEST) of aliphatic component including acid resin, polyvinyl chloride Den resin (PVDC), polyvinyl chloride resin (PVC) and other chlorine resins, α-olefin-carbon monoxide copolymer resin (including hydrogenated resin), α-olefin (ethylene, etc.)-Styrene co Resin composition selected mainly from at least one of polymer resin (containing hydrogenated resin), ethylene-cyclic hydrocarbon compound copolymer resin (containing hydrogenated resin), polyamide resin (Ny), caprolactone resin, etc. Examples thereof include a single layer or a multilayer of these, or a laminate of a resin different from this layer, or a stretched or unstretched substrate made of these resins. Furthermore, the surface energy of the substrate is preferably 34 to 44 mN / m, more preferably 36 to 42 mN / m from the viewpoint of applying the ink composition and the blocking of the substrate, and in some cases corona Surface treatment such as treatment may be performed.

  In addition, for the raw material on which the detection substrate and another substrate are bonded, the oxygen permeability is controlled by the detection substrate or the bonding substrate, and the detection speed, the detection start time, and the color development speed behavior at the time of detection are controlled. May be. In this case, you may use the base material which has a specific function for at least one base material. As a base material which has a specific function, a water vapor | steam barrier, oxygen barrier resin, its base material, etc. are mentioned, for example. When used as an oxygen detection substrate, an oxygen gas barrier resin may be used to control contact between the oxygen detection unit and air.

The oxygen gas barrier resin referred to in the present invention preferably has an oxygen gas permeation amount of 1.0 to 3948.0 ml / m ² / day / MPa, more preferably 10.0 to 2500.0 ml / m. m ² / day / MPa, more preferably 20.0 to 1300.0 ml / m ² / day / MPa. More preferably, it has 20.0-300.0 ml / m < ² > / day / MPa.

The thickness of the oxygen gas barrier substrate layer used in the present invention varies depending on the oxygen gas permeation amount of the resin used, and the oxygen gas permeation amount is 1.0 to 1974.0 ml / m ² / day / MPa. It is preferable to ensure the thickness. For example, when the oxygen gas permeation amount is about 1000 ml / m ² / day / MPa, it can be achieved by using 12 μm polyethylene terephthalate, and the desired oxygen permeability can be adjusted by adjusting the type of resin and its constituent thickness. Can be achieved.

When introducing the detection base material into the oxygen scavenger bag, for example, when oxygen absorption of the oxygen scavenger is desired to be fast, the base material constituting the detection base material constituting a part of the oxygen scavenger bag Is required to have good oxygen permeation, and the oxygen gas permeation amount is preferably 1000 ml / m ² / day / MPa or more. In addition, when quick color change is required when oxygen gas is touched, the base film may be perforated. For example, the hole may be perforated using an electron beam or a needle-like machine. Alternatively, any known method may be used. For example, when heat resistance is required for a base material such as an oxygen scavenger, a film such as polyethylene terephthalate or nylon having heat resistance may be used. A hole may be used. Furthermore, because the substrate film is a product distinction, information such as logos, messages, manufacturing dates, etc. may be printed by a known printing method, and therefore the substrate film is transparent enough to ensure visibility. It is preferable to have. Printing other than the ink composition of the present invention may be performed on either side of the substrate, but preferably the same surface as the application surface of the ink composition of the present invention can be printed by a single multicolor printing machine. And better from a cost perspective. In addition, when using a detection base material in a bag of oxygen scavenger, as a method of improving oxygen permeability and accelerating the oxygen detection speed, in addition to opening a hole in the base film as described above, a breathable film, non-woven fabric Or by sticking paper with the multilayer film of sealant polyethylene, the loss of the substance contained in the oxygen scavenger can be prevented, and fast oxygen detection reactivity can be secured. Furthermore, heat sealing can be realized with sealant polyethylene.

  It is preferable that either the detection base material or the base material to be bonded in the present invention is transparent and the color development behavior and color tone at the time of detection can be confirmed. When checking the color change at the time of detection, in order to differentiate it from other products, the design and color sample at the time of detection may be printed by printing with normally used ink, but the color change at the time of detection In order to confirm, it is preferable that the detection unit does not perform printing or has visibility enough to confirm discoloration. For example, 10 or less is preferable in haze (according to ASTM-D-1003). More preferably, it is 8 or less, More preferably, it is 6 or less.

In the bonding referred to in the present invention, the detection substrate may be bonded to another substrate by a known bonding technique, and for example, a dry or wet lamination method, a thermal lamination method, a resin melt lamination method, or the like can be used.
Any other substrate such as resin, paper, and nonwoven fabric may be bonded to the detection substrate of the present invention. By pasting a base material having another function, it is possible to impart light-shielding properties or UV-cutting properties.
The oxygen-sensing base film of the present invention may be coated with an adhesive, cut into an adhesive label or a band, and processed with an adhesive tape. Such an adhesive process has an advantage that it can be easily introduced into the package.

  The detection base material of the present invention is related to the food packaging described above (fresh fish, raw meat, raw vegetables called three fresh products), for example, side dishes (boiled food, grilled food, steamed food, fried food) sold at supermarkets, convenience stores, etc. It can be used for any applications where it is necessary to check the presence or absence of oxygen concentration in the sealed space, such as packaging of precision machine parts, metal parts such as screws, and electronic boards. In addition to electrical parts packaging such as, it can be used for pharmaceuticals, cosmetics and the like.

A method of storing a package body in an airless state or replacing an inert gas or the like in the package for the purpose of preventing the food from decaying the substrate coated with the ink composition of the present invention and the laminate substrate ( It may be used for the gas replacement method.
The gas replacement referred to in the present invention will be described. The gas replacement in the present invention means that the air in the sealed container is replaced with a desired gas, and includes effects such as improvement in storage stability of the contents and appearance of the product color, such as food (A) anti-oxidation of fat and oil components, (b) preservation of active ingredients such as vitamins, (c) prevention of decay due to the growth of mold, fungi and yeasts, Effective for preventing discoloration / fading and (e) preventing scattering of aroma. Further, the preservation of the contents may be further improved by substituting with a gas having bacteriostatic action such as carbon dioxide gas.

  In general, examples of the gas replacement method include a chamber type and a gas flash type. The chamber-type gas replacement method is a method in which the entire chamber interior is once evacuated to a vacuum state, and the replacement gas is sent as it is to perform gas replacement. Generally, the chamber-type gas replacement method has a gas replacement rate. It has a feature that it is high and can perform gas replacement reliably. On the other hand, the gas flush type gas replacement method is a method of performing gas replacement by flushing the replacement gas directly into the container containing the contents and expelling the air in the container with the replacement gas. There is a gas pack shrink pillow packaging. In general, the gas flush type is said to have a lower gas replacement rate than the chamber type, but a desired gas replacement rate can be obtained by adjusting the gas flush time. The gas flash type is cheaper in equipment than the chamber type, and can reduce the capital investment cost of the contractor. The gas replacement method referred to in the present invention can be appropriately selected from the above-described gas replacement methods and other methods according to the contents (type and shape) in the container, packaging speed, installation space, gas replacement rate, and the like. good. Further, there are a method of oxygen-free packaging using an oxygen scavenger in the package, and a method of gas replacement packaging by sealing the package with a desired gas, which may be selected as appropriate.

Since the ink composition of the present invention and the coated product thereof have alcohol resistance not found in the prior art, alcohols having a bactericidal action may be used in the package to prevent food from being spoiled. The component ratio is preferably 0.5% or more from the effect of bactericidal action, and may be contained up to a saturated vapor state. Alcohol here refers to a compound in which a hydrogen atom of a hydrocarbon is substituted with a hydroxyl group, such as methanol, ethanol, propanol, isopropanol (IPA), butanol and the like. The alcohols of the present invention are preferably ethanol, propanol and isopropanol (IPA) from the viewpoint of food safety, more preferably ethanol, propanol, and still more preferably ethanol.
The ink composition of the present invention can also be used in Shomix A5 (trade name: Showa Carbonic Acid) containing alcohol. Shomix A5 is a carbon dioxide gas containing 5% of alcohol, and is usually mixed with nitrogen gas and used for gas replacement packaging.

<Evaluation of ink composition>
(1) Preparation of ink composition The redox dye, nonvolatile reducing agent, alkaline substance, binder, and solvent described in Tables 1 to 5 were dissolved in a solvent in an ampule container. Thereafter, the ampoule container was sealed, and the volatile reducing agent was put into the sealed ampoule container using a syringe and stirred. After several hours, the color of the pigment disappeared completely, and a colorless ink composition was obtained.

The composition described in the table is specifically as follows.
Ketone resin: Lawer's ketone resin (cyclohexanone and formaldehyde condensate) Cranbar 1717 (trade name)
Shellac resin: natural resin manufactured by Gifu Shellac (shellac resin is an ester compound of resin acid and alcohol, Mw = 7000) white shellac GBN-D (trade name)
Nitrocellulose: Nitrocellulose resin manufactured by akzo Nobel Reducing sugar: Reagent D (+)-glucose manufactured by Kanto Chemical Co., Ltd. Dry lamination adhesive: Dry lamination adhesive A315 (main agent) / A10 (hardening agent) manufactured by Mitsui Takeda Chemical Co., Ltd. Was used at a solid content of 25%.
As other chemical substances, chemical substances manufactured by Kanto Chemical Co., Ltd. were used.

(2) Preparation of printing sample Printing process of ink composition on base material Ink composition prepared in (1) above is printed on a 12 μm transparent polyethylene terephthalate resin film with dots (dot size 3 mmφ) pattern at 1 cm intervals. Printing was performed using a printing machine. The gravure printing machine was used in the gravure printing specification of K303 Multicoater manufactured by Matsuo Sangyo Co., Ltd.

(3) Preparation of gas replacement sealed package The printed sample prepared in the above (2) is gas barrier bag (Hiryu N-9 manufactured by Asahi Kasei Pax Co., Ltd.) together with oxygen absorber (oxygen absorber RP-200 manufactured by WonderKeep). And filled with dry nitrogen and sealed with a heat seal. In the reversibility confirmation experiment, opening in air and the above sealing were repeated, and the discoloration behavior of the printed sample was visually observed.
The gas composition in the gas replacement sealed package after one week was almost 100% nitrogen.

(4) Oxygen and carbon dioxide composition ratio measurement in gas replacement sealed packaging body space Oxygen and carbon dioxide in gas replacement sealing packaging body space at 20 ° C. using a combination check (trade name) oxygen and carbon dioxide measuring device manufactured by PBI Dansensor The composition ratio (% by weight) was measured. The nitrogen concentration was calculated by subtracting the oxygen concentration and carbon dioxide concentration from 100% by weight.

(5) Light resistance evaluation 1
Using a germicidal lamp (GL-20 manufactured by National Corporation) in a dark room adjusted to 20 ° C, the sample was irradiated from a distance of 30 cm, photographed once a day, and the colors of each photo were compared and faded. The spot was measured.
(6) Heat resistance evaluation 1 (heat resistance evaluation of ink composition)
The sealed ink composition was left in a drying oven adjusted to 50 ° C. for 2 weeks, then opened in the air, and the color change of the ink composition before and after opening was visually confirmed.
(7) Heat resistance evaluation 2 (heat resistance evaluation of products coated with ink composition)
The gas replacement sealed package prepared in (3) above was left in a drying oven adjusted to 50 ° C. for 2 weeks, then opened in the air, and the color development state of the ink composition coated product before and after opening was visually confirmed. .

(8) Oxidation-reduction potential measurement The oxidation-reduction potential in 1 weight% aqueous solution of each pigment | dye was measured using Hokuto Denko Co., Ltd. cyclic voltammetry HX-105 (brand name). The measurement was performed using a silver / silver chloride electrode in a 20 ° C. environment. The drawing speed was 50 mV / s, and was drawn from -0.5 V to 1.5 V. The peak value was used for the oxidation-reduction potential, and the values on the low current side were used for those having oxidation-reduction potentials at several places.

[Examples 1 to 9]
The ink composition was prepared on a 12 μm transparent polyethylene terephthalate resin film using a gravure printing machine with dots (dot size 3 mmφ) pattern at 1 cm intervals. Tables 1 and 2 show the composition of the ink composition used at the time of preparation. The produced printing sample showed good reversibility in the oxygen state, and markedly improved functions in heat resistance and light resistance compared to the conventional product (Comparative Example 4).

[Comparative Examples 1-4]
Following the examples, ink compositions and print samples were prepared with the compositions shown in Table 3, and functional evaluation was performed. Comparative Examples 1 to 3 are experiments related to an important substance that seems to exhibit the reversibility of the color change, but none of these substances added did not show the color change of the dye and remained blue. It was. Comparative Example 4 has a conventional reversible composition, but the ink composition had to have a pH of 10.4 in order to exhibit reversibility. Further, the functions of heat resistance and light resistance were poor, and there was a marked difference from the examples of the present invention.

<Evaluation of the fabric>
(9) Preparation of print sample (9-1) Printing process of oxygen detection ink on sheet and film Ink compositions shown in Tables 4 and 5 were prepared in the same manner as “(1) Preparation of ink composition”. Then, the substrate film was prepared using a gravure printing machine with dots (dot size diameter 3 mmφ) at intervals of 1 cm. The gravure printing machine was used in the gravure printing specification of K303 Multicoater manufactured by Matsuo Sangyo Co., Ltd.
(9-2) Dry Laminating Process to Detection Sheet and Film Using the base film on which the oxygen detection ink prepared in (9-1) is applied, a dry lamination agent is applied and dried in advance, and the film described in the table The paper was overlapped so that the surface on which the oxygen detection ink was applied was sandwiched between the films, and was laminated with a laminator pressure roll. The laminating machine was used with a laminator specification of K303 multi-coater manufactured by Matsuo Sangyo Co., Ltd. The laminating temperature was room temperature (23 to 26 ° C.).

(10) Measurement of decoloring time A sample was placed in a room adjusted to 20 ° C., photographed every 30 minutes, the color of the photograph was visually confirmed, and the time when the sample became transparent was defined as the decoloring time.
(11) Measurement of color development time A sample was placed in a room adjusted to 20 ° C., photographs were taken every 30 minutes, and the color of each sample was compared visually to determine where the color change of the sample ceased.

(12) Light resistance evaluation 2
The sample was left in a room adjusted to 20 ° C. in a state of 600 lux using a fluorescent lamp, photographed once a day, and the color of each photograph was compared to measure where the color had faded.
(13) Heat resistance evaluation 3
The printed detection film thus prepared was dry-laminated into a polypropylene sheet (thickness: 120 μm), and the detection sheet was left in a drying oven adjusted to 100 ° C. for 5 minutes (corresponding to heat history during molding). Thereafter, the polypropylene sheet was made into a gas replacement sealed package, and after 3 days, the polypropylene sheet in the gas replacement package was visually observed, then opened to the air, and the color of the pigment was visually confirmed again. .

[Examples 10 to 18]
The films described in Tables 4 and 5 were dry-laminated on the base film coated with the oxygen detection ink, and the dry-laminated oxygen detection base sheet was gas-substituted and packaged with dry nitrogen gas, and the physical properties were confirmed. The results are shown in Tables 4 and 5. Examples 10-18 were all good.

[Example 19]
Moreover, the oxygen detection base film of Example 18 and the cherry kraft paper which has a sealant layer were bonded with the dry laminating agent of Table 5, and the multilayer film for oxygen scavenger pouches was created. Using the multilayer film, a 5 cm × 4 cm sachet was prepared by heat sealing, and the oxygen scavenger composition used in the wonder keep RP200 (trade name) manufactured by Wonder Keep Takatsuki Co., Ltd. used in the examples. Was transferred and sealed with a heat seal. The color of the oxygen detection ink of the prepared oxygen scavenger was blue. The prepared oxygen scavenger was sealed with dry nitrogen in the gas barrier bag used in the examples, and the color of the oxygen detecting ink of the oxygen scavenger after 3 days was observed. The color of the oxygen detection ink of the oxygen scavenger after 3 days was transparent. Subsequently, when the gas barrier bag was broken and exposed to air, it turned blue and oxygen exposure could be indicated by the discoloration.

  The present invention is an ink composition, which can be reversibly changed particularly by the presence or absence of oxygen, and is extremely excellent in durability as compared with the prior art. Moreover, a detection base material can be made by applying the ink composition of the present invention to a base material, and a container and a bag containing the detection base material can be prepared.

Claims (12)

  An ink composition comprising a redox dye, a volatile reducing agent, a non-volatile reducing agent, an alkaline substance, a binder and a solvent.   The ink composition according to claim 1, wherein the binder comprises a cyclohexanone ketone resin or an acetophenone ketone resin.   The redox dye is at least one dye selected from the group consisting of thiazine dyes, oxalin dyes, lactone dyes, sultone dyes, azo dyes, indigoid dyes, anthraquinone dyes, and triphenylmethane dyes. The ink composition according to claim 1, wherein the ink composition is present.   The ink composition according to claim 1, wherein the oxidation-reduction potential of the oxidation-reduction dye is +0.1 V or more and +1.5 V or less.   The ink according to any one of claims 1 to 4, wherein the redox dye is at least one dye selected from the group consisting of methylene blue, thionine, brilliant blue, first green, indigo carmine, and amino black. Composition.   6. The ink composition according to claim 1, wherein the volatile reducing agent is at least one reducing agent selected from the group consisting of ammonia, thiols, aldehydes, and low molecular amines. object.   The ink composition according to any one of claims 1 to 6, wherein the non-volatile reducing agent is at least one reducing agent selected from the group consisting of reducing sugar, ascorbic acid, cysteine, and aldehydes.   The ink composition according to any one of claims 1 to 7, wherein the alkaline substance comprises at least one compound selected from the group consisting of sodium hydroxide, potassium hydroxide, and sodium hydrogen carbonate.   The detection base material which apply | coated the ink composition in any one of Claims 1-8.   An original fabric comprising the detection substrate according to claim 9. A container produced using the detection base material according to claim 9 or the raw material according to claim 10. A bag produced using the detection substrate according to claim 9 or the original fabric according to claim 10.