JP4697364B2 - Ink composition for high-pressure steam sterilization display - Google Patents

Description

【００２０】
上記表１にみられるように、実施例１〜６のインキ組成物による印字品は、７０℃の温水に１時間漬浸した場合、赤味がわずかに薄くなる傾向を示したものがあるものの、殺菌表示用印字として利用するには差し支えない程度であり、印字検査機にて十分未殺菌品として識別できた。それ以外の工程では、特に色の褪色もなく異常はみとめられず、十分耐性のある印字被膜であった。
ちなみに殺菌処理前の缶、あるいは上記の各液に接触処理した缶を印字検査機を通したところ、ラインはストップしこれらが殺菌処理されていない不良缶であると判定した。
また、１１５℃−２０分間の殺菌処理後には印字は消色しており、印字検査機にて全て通過し、殺菌処理が行われたことを示した。
【００２１】
（比較例１〜６）
実施例１で使用した混合溶剤に、表２に記載した処方で呈色剤、発色助剤、バインダー樹脂及び導電剤（ＮａＩ）を溶解し、実施例１と同様にして高圧蒸気殺菌表示用インキ組成物を得、ＩＪＰを使用して金属缶の缶底に印字した。
これらの印字品について、実施例１と同様にして評価した結果を表２に示す。
【００２２】
【表２】

【００２３】
比較例１及び２の印字品は、初期の発色状態は良好であるが、耐温水性に劣り７０℃の温水に触れた直後に黄色に変化した。また、スライダー耐性も悪く、殺菌前のライン搬送時の条件下での耐性を有さないものであり、殺菌前でも印字検査機で殺菌済と判定された。
比較例３〜６の印字品は、初期の発色状態が不良であり、高圧蒸気殺菌表示用インキ組成物としては、不適当なものであった。
【００２４】
（実施例７〜１２）
メタノール：ＭＥＫが３：７の混合溶剤を使用し、表３に記載した処方で呈色剤、発色助剤、バインダー樹脂及び導電剤（ＮａＩ）を溶解し、実施例１と同様にして高圧蒸気殺菌表示用インキ組成物を得、ＩＪＰを使用して金属缶の缶底に印字した。
これらの印字品について、実施例１と同様にして評価した結果を表３に示す。
また、印字状態の評価は次のとおりである。
良好：数字あるいはアルファベットを印字したとき、印字の乱れもなく良好な印字状態である。
やや良：印字の乱れ等ないが、ＩＪＰ励振電圧条件幅がやや狭い。
不良：ＩＪＰ励振電圧条件幅が狭く印字乱れが出やすい。
【００２５】
【表３】

【００２６】
表３によれば、上記実施例７〜１２で得られたインキ組成物は、高圧蒸気殺菌表示用インキ組成物として充分実用に適するものであった。
【００２７】
（実施例１３及び比較例７〜１０）
実施例７で使用した混合溶剤に、表４に記載した処方で呈色剤、発色助剤、バインダー樹脂及び導電剤（ＮａＩ）を溶解し、実施例７と同様にして高圧蒸気殺菌表示用インキ組成物を得、ＩＪＰを使用して金属缶の缶底に印字した。
これらの印字品について、実施例７と同様にして評価した結果を表４に示す。
【００２８】
【表４】

【００２９】
表４によれば、上記実施例１３で得られたインキ組成物は、バインダー樹脂として用いたエピコート1001の軟化温度が５０℃より低いため、耐温水性、耐スライダー性の点でやや退色傾向がみられたものの、高圧蒸気殺菌表示用インキとして使用可能な範囲であった。
一方、上記比較例７〜１０で得られたインキ組成物は、高圧蒸気殺菌表示用インキ組成物としては不適切なものであった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink composition for high-pressure steam sterilization display used for confirmation of a sterilization treatment state in process management of high-pressure steam sterilization treatment in a food field, a medical field, or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, sterilization treatment by heating a can beverage, a retort food, a medical instrument, or the like in a package such as a can or a pouch for a certain time with high-pressure steam has been widely performed.
In these sterilization treatment steps, an ink composition that changes color due to thermal history is printed on the surface of the container filled with the contents using an inkjet printer or the like, and the sterilization state is confirmed by changes in the color of the printed characters and patterns. It has been proposed.
[0003]
For example, JP-A-4-1280 discloses a wet heat discolorable ink composition for an ink jet printer (IJP) containing methyl yellow (dye) and an organic acid or a salt thereof. This ink composition utilizes the fact that methyl yellow is relatively insoluble in water and reversibly changes from the original yellow to red in the presence of an organic acid or a salt thereof. That is, under high-pressure steam sterilization conditions, first, an organic acid or a salt thereof is eluted from the ink coating, methyl yellow returns from red to yellow, and then methyl yellow, which is hardly soluble in water, elutes in high-temperature water. Therefore, the ink film is further irreversibly lightened.
However, since an organic acid or a salt thereof easily dissolves in warm water, an ink film printed with this ink composition can be heated at 40 to 50 ° C. used in the production line before the sterilization treatment, Since it discolored irreversibly just by touching the lubricating water (slider), it was not suitable for practical use as a high-pressure steam sterilization display ink.
[0004]
Japanese Patent Application Laid-Open No. 8-3494 discloses an ink composition for an ink jet printer that contains a dye that sublimes or decomposes by heat and changes its color depending on a temperature history. This ink composition utilizes the fact that a dye is sublimated or decomposed by heat or high-pressure steam and recorded as a color change.
However, when this ink composition is printed on a can, for example, and sterilized by heating with high-pressure steam, the dye film may not sublime and the ink film may not be discolored, and the discoloration is not clear or uniform, The sterilization treatment could not be clearly indicated by the discoloration of the ink film.
[0005]
[Problems to be solved by the invention]
Therefore, the present invention solves these problems of the prior art, and the ink film printed with IJP or the like on the surface of a package such as a can or pouch filled with contents is heated with hot water or sterilized before sterilization with high-pressure steam. It retains its original color tone without discoloring even when it touches a slider, etc., and after the prescribed sterilization treatment, the ink film can be discolored or decolored to clearly indicate that the sterilization treatment has been performed. An object of the present invention is to provide an ink composition for high-pressure steam sterilization display.
[0006]
[Means for Solving the Problems]
The ink composition for high-pressure steam sterilization display of the present invention has the following configuration in order to solve the above problems.
1. Colorant comprising 0.2 to 7% by weight methyl yellow or 0.3 to 10% by weight crystal violet lactone, 0.3 to 10% by weight phenolic hydroxyl group and aromatic nucleus substituted halogen based on the total composition An ink composition for high-pressure steam sterilization display, comprising a coloring aid selected from triphenylmethane-based sulfolactone compounds having an amount of 15% and 35% by weight of a binder resin and no calcium halide . .
2. 2. The ink composition for high-pressure steam sterilization display according to 1, wherein the softening temperature of the binder resin is 50 ° C. or higher.
3. The ink composition for high-pressure steam sterilization display according to 1 or 2, further comprising 0.1 to 5% by weight of a conductive agent based on the total composition.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the ink composition for high-pressure steam sterilization display of the present invention, methyl yellow or crystal violet lactone is used as a colorant. These colorants can be used alone or in combination. Furthermore, these dyes can be used in admixture with other dyes.
When methyl yellow is used as a color former, the ink film printed on the surface of a package or the like develops a red color by the action of a coloring aid before sterilization with high-pressure steam, and light after sterilization. Fading to yellow to colorless.
The content of methyl yellow in the ink composition is preferably 0.2 to 7% by weight, particularly 0.3 to 2% by weight, based on the total composition. When the content of methyl yellow is less than 0.2% by weight, the color of the ink film before the sterilization treatment is not sufficient, and it becomes difficult to confirm the discoloration of the ink film before and after the sterilization treatment. In addition, if the content exceeds 7% by weight, methyl yellow may remain dyed in the ink coating even after sterilization treatment, which may be mistaken as an unsterilized product despite being sterilized. is there.
[0008]
Further, when crystal violet lactone is used as the color former, the ink film is colored green to dark blue green by the action of the color forming aid before the sterilization treatment, and is decolored and colorless after the sterilization treatment.
The crystal violet lactone content in the ink composition is preferably 0.3 to 10% by weight, particularly 1 to 6% by weight, based on the total composition. When the content of crystal violet lactone is less than 0.3% by weight, the color of the ink film before the sterilization treatment is not sufficiently developed, and it becomes difficult to confirm the discoloration of the ink film before and after the sterilization treatment. Moreover, when content exceeds 10 weight%, it will become difficult to melt | dissolve in a solvent and ink preparation will become difficult.
Since these colorants are eluted in hot water under sterilization conditions using high-pressure steam, it is considered that the ink film fades from pale yellow to colorless.
[0009]
In the ink composition of the present invention, a triphenylmethane sulfolactone compound having a phenolic hydroxyl group and an aromatic nucleus-substituted halogen is used as a color forming aid. Such triphenylmethane-based sulfolactone compounds are known as dyes, such as bromophenol blue, bromocresol green, chlorophenol red, bromochlorophenol blue, bromophenol red, bromothymol blue, bromocresol purple, and the like. It is done. These compounds can be used singly or in combination of two or more. Coloring agents such as methyl yellow are colored from yellow to red, and crystal violet lactone is colored from colorless to blue.
These coloring aids are hardly soluble in water, and even when exposed to hot water, they are compared with organic acids or their salts and phenolic coloring agents used in conventional ink compositions. Therefore, it is possible to prevent the ink film from being discolored by warm water or a slider before sterilization.
[0010]
In the ink composition of the present invention, the ink film printed on the surface of the package is stable before sterilization with high-pressure steam by using a combination of the specific colorant and the specific color forming aid described above. The color tone is maintained, and after a predetermined sterilization treatment, the color fades from pale yellow to colorless, and it is possible to clearly display that the sterilization treatment has been performed.
When the color of the ink coating changes from colored to colored before and after the sterilization treatment, it is generally difficult to automatically monitor the sterilization state on the production line with, for example, a printing inspection machine, etc. Is required. In the ink composition of the present invention, the color of the ink film fades from colored to colorless or extremely pale yellow before and after the sterilization treatment, so that automatic monitoring by a printing inspection machine or the like is possible, and production efficiency can be improved. Become. That is, if the color of the ink film by the ink composition of the present invention is insufficiently sterilized or not sterilized and remains on the surface of the package, the print inspection machine recognizes a print defect or print stain and issues an alarm. Automatic monitoring is possible.
[0011]
As the binder resin used in the ink composition of the present invention, a binder resin used in a normal ink composition can be used. When the ink composition is applied by IJP, there are restrictions on the viscosity of the composition, and the softening temperature of the resin can be determined in consideration of the warm water resistance of the resulting ink film and the leachability of the colorant and coloring aid. However, it is preferable to use a resin having a temperature of 50 ° C. or higher, particularly 60 ° C. or higher.
Examples of such binder resins include epoxy resins, novolac resins, acrylic resins, vinyl chloride resins, vinyl chloride vinyl acetate copolymer resins, polyester resins, polyamide resins, and rosin-modified resins. These resins can be used alone or in combination of two or more.
[0012]
The blending amount of the binder resin is preferably 15 to 35% by weight based on the total composition. If the blending amount of the resin is less than 15% by weight, the warm water resistance of the resulting ink film is inferior, and if it exceeds 35% by weight, the viscosity of the ink composition becomes high and the applicability deteriorates, for example by IJP. Application becomes difficult.
In the binder resin, a resin having a softening temperature of less than 50 ° C. can be added as long as the warm water resistance of the ink composition is not impaired. The amount of such a resin is based on the total binder resin. It is preferable to keep it at 40% by weight or less.
In addition, leveling agents such as silicone or modified silicone and wax, additives such as surfactants and lubricants, and modifiers such as rosin acid, fatty acids, and natural fats and oils are added to supplement the properties and application properties of the ink film. May be. In addition, an organic acid or a salt thereof, or a dihydric phenol may be used as an auxiliary color forming aid as long as the properties of the ink composition are not impaired.
[0013]
In the heat history display ink composition of the present invention, it is preferable to blend a conductive substance in order to stably perform the printing by the charge type IJP. As the conductive substance, alkali metal salts such as lithium salts, potassium salts, sodium salts, thiocyanates, organic acids and salts thereof, and the like used for ordinary IJP inks can be used. It is preferable to use an alkali metal iodide such as potassium iodide or sodium iodide. You may use these individually or in mixture of 2 or more types.
The blending amount of the conductive substance in the heat history display ink composition is preferably 0.1 to 5% by weight based on the total composition.
[0014]
The high-pressure steam sterilization indicating ink composition of the present invention is usually prepared as a solution or dispersion in which each of the above components and other components added as necessary are dissolved or dispersed in various solvents. The obtained composition is applied to a surface of a container such as a can, a plastic bottle, or a plastic pouch containing beverages, retort foods, medical equipment, medicines, etc. It can also be applied by ordinary marking or coating methods. In addition, the ink composition of the present invention can also be used by sticking to a food or a package in the form of a label on which the ink composition is printed or applied. In these cases, it is not necessary to add a conductive agent.
In addition to applying the present ink composition to individual packages and using it as a means for determining the presence or absence of sterilization, for example, an indicator coated with the present ink composition is placed in a sterilization pot together with an object to be sterilized. By sterilizing, it can also be applied as means for confirming the sterilization state in batch units.
Examples of the solvent include ordinary solvents such as alcohols, esters, ketones, alkylene glycol ethers, ethers, furans, aromatic hydrocarbons, chlorine-based water, and the like. These can be used alone or in combination.
In addition to the above-mentioned components, other compounding agents such as a plasticizer, an organic acid or an auxiliary colorant such as a salt thereof can be appropriately blended with the high-pressure steam sterilization display ink composition of the present invention.
[0015]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention, these Examples do not limit this invention.
Moreover, the compounding quantity of the component which comprises an ink composition in a following example and a comparative example is displayed with weight% on the basis of the whole composition, and the residual amount of an ink composition is a solvent.
Example 1
In a mixed solvent of methanol: methyl ethyl ketone (MEK) 3: 7, methyl yellow (MY) 0.5% as a colorant, bromothymol blue (BTB) 3% as a coloring aid, rosin-modified maleic acid resin as a binder resin 25% was dissolved, and then 1% sodium iodide (NaI) was dissolved as a conductive agent to obtain an ink composition for high-pressure steam sterilization display.
This ink composition was filtered through a 1 micron filter and printed on the bottom of a metal can using an ink jet printer (IJP). The dried ink film developed a red color and the printing state was very good. .
[0016]
(Examples 2 to 6)
In the mixed solvent used in Example 1, a colorant, a coloring aid, a binder resin, a conductive agent (NaI), and a silicone surfactant were dissolved according to the formulation shown in Table 1, and high pressure was obtained in the same manner as in Example 1. An ink composition for steam sterilization display was obtained and printed on the bottom of a metal can using IJP.
[0017]
[Evaluation]
The IJP-printed product using the high-pressure steam sterilization indicating ink composition obtained in each of the above examples was evaluated by the method described below, and the results are shown in Table 1.
(Color development state)
The color development state of the dried ink film was visually determined.
Good: sufficiently colored and easily distinguishable from uncoated products or sterilized decolored products by a printing inspection machine.
Slightly good: Although the color development is slightly thin, it can be distinguished from an uncoated product or a sterilized decolored product by a printing inspection machine.
Poor: The color development state is weak or no color development occurs. Cannot be discriminated from uncoated products or sterilized decolored products by a printing inspection machine.
(Hot water resistance)
It was immersed in warm water at 70 ° C. and the color change was observed after 1 hour.
Good: No color fading is observed.
Slightly fading: Although there is a slight fading tendency, it can be identified as a non-sterile product by a printing inspection machine.
Defect: Fading is seen, and it passes without being identified as an unsterilized product by a printing inspection machine.
(Slider resistance)
It was immersed in a slider (weakly alkaline lubricating water) and the color change was observed after 1 hour.
Good: No color fading is observed.
Slightly fading: Although there is a slight fading tendency, it can be identified as a non-sterile product by a printing inspection machine.
Defect: Fading is seen, and it passes without being identified as an unsterilized product by a printing inspection machine.
(High-pressure steam sterilization and decolorization)
After a sterilization treatment at a peak temperature of 115 ° C. for 20 minutes using a predetermined high-pressure steam sterilizer, the color change of the ink film was observed.
Good: The color is colorless and erased, and is identified as a sterilized product by a printing inspection machine.
Slightly good: Although there is a little color residue, it is identified as a sterilized product by a printing inspection machine.
Defective: A colored color remains, and is identified as an unsterilized product by a print inspection machine.
[0018]
In Tables 1 to 4 below, each component constituting the ink composition is represented by the following abbreviations.
(Coloring agent)
MY: Methyl yellow CVL: Crystal violet lactone (coloring aid)
BTB: bromothymol blue CPR: chlorophenol red BPB: bromophenol blue BCG: bromocresol green SA: salicylic acid SAZn: zinc salicylate TB: thymol blue NP: naphthol phthalene (binder resin)
End-blocking 1001: End-group blocking epoxy resin 1001 (equivalent to Epicoat 1001)
End-blocking 1004: End-group blocking epoxy resin 1004 (equivalent to Epicoat 1004)
Modified phenol: Rosin modified phenolic resin Tespol 1305
Modified Malein: Rosin-modified maleic acid resin Tespol 1105
1001: Epicote 1001
Acrylic: Acrylic resin (Acryloid B60)
PVC: Vinyl chloride resin (VAGH)
Of the above binder resins, Epicoat 1001 has a softening temperature lower than 50 ° C., and end group-capped epoxy resins 1001 and 1004 and the other resins have a softening temperature of 50 ° C. or higher.
[0019]
[Table 1]

[0020]
As can be seen in Table 1 above, the printed products of the ink compositions of Examples 1 to 6 have a tendency that the redness tends to be slightly thinner when immersed in warm water at 70 ° C. for 1 hour. It was in a level that could be used as a sterilization display print, and could be sufficiently identified as a non-sterile product by a print inspection machine. In the other processes, there was no particular discoloration and no abnormality was observed, and the printed film was sufficiently resistant.
By the way, when the can before the sterilization treatment or the can subjected to the contact treatment with each of the above liquids was passed through the printing inspection machine, the line was stopped and it was determined that these were defective cans that were not sterilized.
In addition, the print was decolored after the sterilization treatment at 115 ° C. for 20 minutes, and all passed through the print inspection machine, indicating that the sterilization treatment was performed.
[0021]
(Comparative Examples 1-6)
In the mixed solvent used in Example 1, a colorant, a coloring aid, a binder resin, and a conductive agent (NaI) were dissolved according to the formulation shown in Table 2, and high pressure steam sterilization display ink was prepared in the same manner as in Example 1. A composition was obtained and printed on the bottom of a metal can using IJP.
Table 2 shows the results of evaluating these printed products in the same manner as in Example 1.
[0022]
[Table 2]

[0023]
The printed products of Comparative Examples 1 and 2 had good initial color development, but were inferior in warm water resistance and turned yellow immediately after touching 70 ° C. warm water. Also, the slider resistance was poor, and it did not have resistance under the conditions during line conveyance before sterilization, and was determined to be sterilized by a print inspection machine even before sterilization.
The printed products of Comparative Examples 3 to 6 were inferior in the initial color development state, and were unsuitable as an ink composition for high-pressure steam sterilization display.
[0024]
(Examples 7 to 12)
A mixed solvent of methanol: MEK of 3: 7 was used, and the colorant, coloring assistant, binder resin and conductive agent (NaI) were dissolved in the formulation shown in Table 3, and high pressure steam was used in the same manner as in Example 1. An ink composition for sterilization display was obtained and printed on the bottom of a metal can using IJP.
Table 3 shows the results of evaluating these printed products in the same manner as in Example 1.
The evaluation of the printing state is as follows.
Good: When numbers or alphabets are printed, the printing state is good without any disturbance in printing.
Slightly good: There is no printing disturbance, but the IJP excitation voltage condition range is slightly narrow.
Defect: The IJP excitation voltage condition width is narrow and printing disturbance tends to occur.
[0025]
[Table 3]

[0026]
According to Table 3, the ink compositions obtained in Examples 7 to 12 were sufficiently suitable for practical use as an ink composition for high-pressure steam sterilization display.
[0027]
(Example 13 and Comparative Examples 7 to 10)
In the mixed solvent used in Example 7, a colorant, a coloring aid, a binder resin, and a conductive agent (NaI) were dissolved according to the formulation described in Table 4, and high pressure steam sterilization display ink was obtained in the same manner as in Example 7. A composition was obtained and printed on the bottom of a metal can using IJP.
Table 4 shows the results of evaluating these printed products in the same manner as in Example 7.
[0028]
[Table 4]

[0029]
According to Table 4, the ink composition obtained in Example 13 has a slightly fading tendency in terms of hot water resistance and slider resistance because the softening temperature of Epicoat 1001 used as the binder resin is lower than 50 ° C. Although it was observed, it was in a range that could be used as an ink for high-pressure steam sterilization display.
On the other hand, the ink compositions obtained in Comparative Examples 7 to 10 were inappropriate as an ink composition for high-pressure steam sterilization display.

Claims (3)

Colorant comprising 0.2 to 7% by weight methyl yellow or 0.3 to 10% by weight crystal violet lactone, 0.3 to 10% by weight phenolic hydroxyl group and aromatic nucleus substituted halogen based on the total composition An ink composition for high-pressure steam sterilization display, comprising a color forming aid selected from triphenylmethane-based sulfolactone compounds having an acid content , 15 to 35% by weight of a binder resin, and no calcium halide . 2. The ink composition for high-pressure steam sterilization display according to claim 1, wherein the softening temperature of the binder resin is 50 ° C. or higher. The ink composition for high-pressure steam sterilization display according to claim 1 or 2, further comprising 0.1 to 5% by weight of a conductive agent based on the total composition.