JPH1180637A - Ink composition indicating heat history and packaging material having indication made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ink composition capable of irreversibly indicating accumulations of heat history and of the lapse of time by including a volatile organic amine having a specified structure, a dye which discolors upon a pH change and a binder resin. SOLUTION: 0.03-20 wt.% volatile amine represented by the formula (wherein R1 To R3 are each H, a 1-8C alkyl or a hydroxyalkyl of the formula: R1 -OH; and R4 is a 1-5C alkylene) and having a boiling point of 100-360 deg.C, 0.1-10 wt. %, desirably 0.5-5.0 wt. % dye which discolors at a pH of 3-10, desirably 9 or below and shows a color difference of at least 20 between the initial hue and the hue after discoloration and 1.0-30 wt.%, desirably 2-20 wt.% binder resin selected among acrylic resins, amino resins, epoxy resins, phenolic resins, polyester resins, vinyl chloride resins, vinyl acetate resins, polyamide resins, chlorinated vinyl acetate resins and alkyd resins are dissolved or dispersed in a solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat history display ink composition capable of cumulatively and irreversibly displaying the history of heat and the passage of time, and a package having a display using the composition.

[0002]

2. Description of the Related Art Conventionally, various heat history display inks have been proposed which use the change in color tone of a display to indicate the storage or expiration date of a canned beverage, retort food or medicine.
For example, JP-B-6-53868 discloses a thermochromic ink composition containing a heat-resistant dye and a heat-sensitive dye, wherein the heat-sensitive dye is decomposed and discolored when subjected to a high temperature for a predetermined time. However, this ink composition changes color only when heated at a temperature of 116 ° C. or higher for 15 to 30 minutes, and can clearly indicate the time lapse of 1 to 3 months at a temperature of 100 ° C. or lower. Not something.

Further, Japanese Patent Publication No. 64-2906 discloses that
A time indicator that utilizes the coexistence of a variable dye that changes color in response to a change in pH and an inorganic alkaline substance such as sodium hydroxide, and that the inorganic alkaline substance reacts with carbon dioxide gas in the air and changes its color due to a decrease in pH. Although described, the reaction with carbon dioxide gas proceeds even before the indicator is attached to a can or the like, so that it was necessary to save the air until immediately before use. Also,
It could not reflect changes due to temperature and did not clearly indicate the thermal history.

Further, Japanese Patent Application Laid-Open No. 61-12784 discloses a reversible temperature indicator containing an acid-base indicator and a fusible compound capable of changing pH. It is made reversible by enclosing a substance, and simply shows the temperature at that time, and does not show the heat history over time.

[0005]

In recent years, with the change in the distribution form of products such as the spread of vending machines and convenience stores, canned beverages are sold by heating retort foods and the like at vending machines and stores. Is becoming widely practiced.
In a product in such a sales form, not only the elapsed time after manufacture but also what kind of heat history the product has received after manufacture, that is, the heat history of the product and the lapse of time are accumulated and calculated in a simple manner. It is necessary to grasp irreversibly and perform quality control such as the expiration date of the product. However, none of the above-mentioned conventional time indicators satisfy all of these requirements. Therefore, the object of the present invention is
An object of the present invention is to provide a heat history display ink composition which solves the problems of the prior art and can easily and clearly accumulate a heat history and a lapse of time after the product has been manufactured and can irreversibly display the heat history. .

[0006]

According to the present invention, in order to solve the above-mentioned problems, a volatile organic amine, a dye which changes its color due to a change in pH, and a binder resin are contained in the thermal history display ink composition to reduce the time. And a heat history indicating ink composition which can be irreversibly displayed by accumulating the progress of temperature. In this heat history display ink composition, the organic amine is volatilized by heating in a vending machine or in a store, and the dye is discolored due to a decrease in the pH of the composition, and irreversible by accumulating the passage of time and heat history. Is displayed in a typical manner. Therefore, the heat history display ink composition of the present invention can be applied to the surface of a package containing beverages, retort foods, and the like by, for example, inkjet printing or coating, so that the passage of time and the heat history of the container can be easily visualized. And it can be clearly understood.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As the volatile organic amine used in the present invention, any organic amine having a boiling point of 100 to 360 ° C. can be used. Preferred organic amines include aliphatic organic amines represented by the following general formula (1).

[0008]

Embedded image

Specific examples of the aliphatic amine used in the present invention include n-dibutylamine, n-tributylamine, diisobutylamine, diamylamine, triamylamine, n-heptylamine, 2-ethylhexylamine and dioctyl. Examples include amine, diethylenetriamine, tetraethylenepentamine, cyclohexylamine and the like. Among the aliphatic amines, at least one of R ₁ , R ₂ , and R _{3 in} the general formula (1) is R
_The use of alkanolamines which are _4- OH is particularly preferred because the odor of the amine is small. Suitable alkanolamines include, for example, monoethanolamine, diethanolamine, triethanolamine, ethyl monoethanolamine, n-butyl monoethanolamine, dimethylethanolamine, diethylethanolamine, ethyldiethanolamine, n-butyldiethanolamine, di-n- Butylethanolamine, triisopropanolamine and the like. These volatile amines volatilize from the thermal history indicating ink composition according to the passage of time and the degree of thermal history, and the pH of the composition decreases. The compounding amount of the volatile organic amine is about 0.03 to 20% by weight based on the total composition, and is appropriately selected within this range depending on the concentration of the dye to be used and the required discoloration time. If the amount of the amine is more than this, the drying property of the film is not sufficient, and if the amount is less, the coloring is not sufficient.

As the dye used in the present invention, which changes color due to a change in pH, any dye which changes color in the range of pH 3 to 10 can be used. And a dye which has a color difference ΔE of 20 or more after completion of discoloration and does not sublimate by heat at the time of storage and sale by heating. When such a dye is used, the discoloration of the composition can be easily determined visually, and the hue of three colors can be changed with a single dye.
For example, it is possible to identify the progress at an intermediate time, such as when one or two months have passed.

Examples of such dyes include those selected from triphenylmethane dyes having a lactone or sulfophthalein ring structure and having at least one phenolic hydroxyl group. Triphenylmethane dyes are generally easily oxidized by air, but those having the above-mentioned specific structure having a lactone or sulfophthalein ring are stable against thermal oxidation, and a single dye can change the hue of three colors. . The dye has a melting point of 130 ° C. or more,
Preferably, it is selected from those of 170 ° C. or higher. If the melting point is lower than this, it tends to sublimate during heating and aging, and to chemical changes such as oxidation. Specific examples of such a dye include, for example, bromocresol green, bromophenol blue, bromochlorophenol blue, bromophenol red, bromothymol blue, cresol red, bromocresol purple,
Chlorophenol red, xylenol orange, p-
Examples include triphenylmethane dyes such as xylenol blue, phenolsulfophthalein, xylenol orange, xylenol blue, thymol blue, and m-cresol purple. These may be used alone or in combination of two or more. The amount of these dyes incorporated into the thermal history indicating ink composition is about 0.1 to 10% by weight, preferably about 0.5 to 5.0% by weight, based on the total composition. Further, for the purpose of supplementing these color tones, other dyes can be added within a range that does not impair the initial color of the dye of the present invention. For example, methyl red, acid red 2, mordan red 3 and the like can be mentioned.

The binder resin used in the thermal history indicating ink composition of the present invention is not particularly limited as long as it can ensure the adhesion of the composition to a substrate such as a can and the tackiness of the composition. Instead, any of those commonly used as binder resins can be used. Preferred examples of the binder resin include an acrylic resin, an amino resin, an epoxy resin, a phenol resin, a polyester resin, a vinyl chloride resin, a vinyl acetate resin, a polyamide resin, a vinyl chloride resin, and an alkyd resin. These resins can be used alone or in appropriate combination of two or more kinds, and a copolymer of these resins may be used. Further, it is also possible to add an additive for compensating the properties and application suitability of these resin films. For example, a leveling agent,
Surfactants and the like. In addition, a modifier such as rosin acid, fatty acid, natural fat or the like may be used by mixing with these binder resins. The compounding amount of the binder resin is about 1.0 to 30% by weight, preferably about 2 to 20% by weight of the entire thermal history indicating ink composition.

The heat history indicating ink composition of the present invention is usually prepared as a solution or dispersion in which the above-mentioned components and other components added as necessary are dissolved or dispersed in various solvents. The resulting composition can be used for beverages, retort foods, surfaces of containers such as cans or plastic bottles containing plastics, pouches, paper containers, etc., or various other types requiring management of heat history during distribution and sale. It is applied to the surface of a package or the like by an ordinary marking method such as an ink jet printer, a stamp, a coater or the like. The ink composition of the present invention can also be used by sticking it to food or a package in the form of a label coated with the ink composition. As the solvent, for example, usual ones such as alcohols, esters, ketones, alkylene glycol ethers, ethers, furans, aromatic hydrocarbons, chlorine, and water are used. These can be used alone or in combination.

[0014] In addition to the above components, the thermal history indicating ink composition of the present invention includes, for example, a conductivity-imparting substance for imparting chargeability when used as an ink for an ink jet printer, a plasticizer, an auxiliary colorant and the like. It is also possible to appropriately mix other compounding agents.

[0015]

Next, the present invention will be described with reference to examples, but the following examples do not limit the present invention. (Examples 1 to 5) According to the mixing ratio of the organic amine, the dye and the resin shown in Table 1, the mixture was dissolved in a solvent and sufficiently stirred and mixed. The mixed and dissolved ink composition was filtered using a 1 μm filter to remove particles having a size of 1 μm or more to prepare the thermal history display ink compositions of Examples 1 to 5. In the following tables, the amounts of organic amines and dyes are indicated by weight% of the total composition. MEK is methyl ethyl ketone, MeOH is methanol, AC is acetone, THF
Represents tetrahydrofuran, TEA represents triethanolamine, DEA represents diethanolamine, DEEA represents diethylethanolamine, and DBEA represents dibutylethanolamine.

[0016]

[Table 1]

(Examples 6 to 10) In the same procedure, the thermal history indicating ink compositions of Examples 6 to 10 were prepared according to the mixing ratios of the organic amine, dye and resin shown in Table 2.

[0018]

[Table 2]

These inks were applied on a metal plate so as to have a thickness of 3 to 4 μm, dried, and stored at room temperature for a long time. However, these ink films maintain the initial color tone even after storage. Was. In addition, these ink films maintained the color tone at the time of completion of discoloration even when heating was continued at 90 ° C. for 3 months or more, and no change such as color reduction was caused by sublimation. When the inks of these examples were applied to a can using an ink jet printer, clear display marks were obtained. Next, the can body coated with the ink was placed in a thermostat and stored at a predetermined temperature.
Tables 1 and 2 show the elapsed time of discoloration and the color tone with respect to the heating temperature. Each of the ink compositions of Examples 1 to 10 showed a clear three-color change according to the integration of the temperature and the time, and it was found that the color difference between the initial hue and the completion of the color change was 20 or more. It was possible to visually determine the passage of time by the difference in color. The color difference is measured by Nippon Denshoku Co., Ltd.
This was performed using a color difference meter.

Example 11 After marking and packing a PET bottle filled with a juice beverage using the ink composition of Example 1, the product was transported to Thailand and stored in a local warehouse for five months in summer. After returning to Japan by boat again, the color of the mark was examined. About 7.5 months have passed since the bottle was marked. The color tone of the mark changes to yellow-green and the color difference is 6
8, indicating that the product had undergone a heat history corresponding to storage at a temperature of 55 ° C. for about 2.5 months. By the way, the juice that had been packed was quite brown.

Example 12 A banana produced in Okinawa was affixed with a label marked with the ink composition of Example 5 and packed in a carton case, covered with a vinyl sheet for one week before shipment, and outdoors. I left it. After examining the color tone of the label affixed to the banana in the carton stacked on the top, the label changed to bluish green, and the banana in the carton was slightly darkened and partially damaged. there were. Since the color difference was 28, it was found that the banana had undergone a thermal history at 55 ° C. corresponding to about 3 days.

(Comparative Examples 1 to 6) As comparative examples, the discoloration of ink compositions prepared using the resin and solvent of Example 1 except for the components shown in Table 3 was examined. When the amount of addition was small, the boiling point of the organic amine was low, or the dye had a high pH discoloration range, etc., none of them could satisfy the object of the present invention.

[0023]

[Table 3]

[0024]

The heat history indicating ink composition of the present invention, which changes color by the temperature and time history, has a large color difference between the initial color tone and the color tone upon completion of the color change and shows three color changes. It can be clearly distinguished. Also, by appropriately changing the combination of the kind and the amount of the dye and the organic amine, various preservation conditions can be easily adjusted, and the invention has a high practical value.

Claims (7)

[Claims] 1. A heat history display ink composition for irreversibly displaying the accumulation of time and temperature, characterized by containing a volatile organic amine, a dye that changes color by a change in pH, and a binder resin. 2. The thermal history display ink composition according to claim 1, wherein the volatile organic amine is represented by the following general formula (1). Embedded image 3. The thermal history display ink composition according to claim 1, wherein the dye discolors at a pH of 9 or less, and has an initial hue and a color difference after completion of the discoloration of 20 or more. 4. The dye according to claim 1, wherein the dye is selected from triphenylmethane dyes having a lactone or sulfophthalein ring structure and has at least one phenolic hydroxyl group. 4. The thermal history display ink composition according to any one of items 3 to 3. 5. A composition according to claim 1, which contains from 0.03 to 20% by weight of volatile organic amine and from 0.1 to 10% by weight of dye, based on the total composition.
Item 15. The thermal history indicating ink composition according to item 6. 6. The method according to claim 1, wherein the binder resin is selected from an acrylic resin, an amino resin, an epoxy resin, a phenol resin, a polyester resin, a vinyl chloride resin, a vinyl acetate resin, a polyamide resin, a vinyl chloride resin and an alkyd resin. The thermal history display ink composition according to any one of claims 1 to 5, which is characterized in that: 7. A package having a display using the thermal history display ink composition according to claim 1.