JP7190297B2 - Water-based ink composition for inkjet, method for suppressing fading of printed image of solid formulation, and solid formulation - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water-based inkjet ink composition, a method for suppressing fading of a printed image of a solid formulation, and a solid formulation. More specifically, the present invention relates to a water-based inkjet ink composition capable of suppressing fading and discoloration of printed images formed on the surface of solid preparations such as pharmaceuticals and foods, and a method for suppressing fading of printed images of solid preparations. and solid formulations.

Ink jet inks for tablets, capsules, and the like are roughly classified into pigment inks in which pigments are dispersed and dye inks in which dyes are used. Dye inks are excellent in color development, but have problems with humidity resistance and light resistance. Specifically, dye ink has problems such as bleeding due to moisture and fading due to light. On the other hand, pigment inks are excellent in moisture resistance and light resistance, but are inferior in color development compared to dyes.

US Pat. No. 6,200,000 discloses an edible ink that has the advantages of both dyes and pigments described above. Specifically, Patent Document 1 discloses a lake pigment ink in which a lake pigment is dispersed. A lake pigment is a pigment obtained by insolubilizing a water-soluble dye. Therefore, the lake pigment ink has vividness like that of the dye ink, and at the same time has moisture resistance because it is pigmented.

However, since the lake pigment contained in the lake pigment ink is originally a dye, there remains a problem in terms of light resistance. That is, the printed image fades due to the photodecomposition of the dye contained as a component of the lake pigment, and the saturation decreases.

Japanese translation of PCT publication No. 2000-507820

An object of the present invention is to provide an aqueous inkjet ink composition capable of suppressing fading of printed images on the surface of solid formulations such as pharmaceuticals and foods, a method for suppressing fading of printed images of solid formulations, and solid formulations. That's what it is.

One embodiment of the present invention provides an aqueous inkjet ink composition for use in printing solid formulations. The aqueous inkjet ink composition includes an edible lake pigment and a fade inhibitor. The lake pigment comprises a dye containing at least one selected from the group consisting of Red No. 2, Red No. 3, Red No. 40, Red No. 102, Yellow No. 4, Yellow No. 5, Blue No. 1 and Blue No. 2. Contains specific lake pigments. The anti-fading agent contains at least one selected from the group consisting of monosaccharides, disaccharides, dextrins and sugar alcohols. The content of the anti-fading agent is 50% by mass or less with respect to the total mass of the water-based ink composition. The lake pigment may contain, as an optional component, a lake pigment other than the specific lake pigment.

In the above configuration, the dye, which is a component of the specific lake pigment, has the property of being decomposed (photodecomposed) by light irradiation. However, fading inhibitors function to inhibit photodegradation for certain lake pigments containing such dyes. Therefore, in the water-based ink composition having the above structure, it is possible to reduce deterioration of printed images due to discoloration.
Furthermore, since the content of the fading inhibitor is 50% by mass or less with respect to the total weight of the aqueous ink composition, the fading inhibitor is prevented from being sufficiently dissolved in the aqueous ink composition and precipitated. Can be suppressed or prevented.

In the above configuration, the monosaccharide preferably contains at least one of galactose and fructose.
In the above configuration, the disaccharide preferably contains at least one of maltose and trehalose.
In the above configuration, the dextrin preferably contains cyclodextrin.

In the above configuration, the sugar alcohol preferably contains at least one selected from the group consisting of reduced isomaltulose, xylitol and sorbitol.
Moreover, one embodiment of the present invention provides a method for suppressing fading of a printed image printed on a solid formulation. This method includes a preparation step of preparing an aqueous inkjet ink, a printing step of forming the printed image on the surface of the solid preparation by an inkjet method using the aqueous inkjet ink, and a discoloration suppression step. The water-based inkjet ink contains an edible lake pigment and a fade inhibitor. The lake pigment comprises a dye containing at least one selected from the group consisting of Red No. 2, Red No. 3, Red No. 40, Red No. 102, Yellow No. 4, Yellow No. 5, Blue No. 1 and Blue No. 2. Contains specific lake pigments. The anti-fading agent contains at least one selected from the group consisting of monosaccharides, disaccharides, dextrins and sugar alcohols. The content of the anti-fading agent is 50% by mass or less with respect to the total mass of the water-based ink composition. The lake pigment may contain, as an optional component, a lake pigment other than the specific lake pigment.

The fading suppressing step is a step in which the fading suppressing agent in the printed image suppresses photodecomposition of the specific lake pigment.
In this method, an aqueous inkjet ink containing an aqueous ink composition containing a discoloration inhibitor such as a monosaccharide is prepared (preparation step), and the aqueous ink is used to print on the surface of a solid preparation by an inkjet method ( printing process). Further, the fading inhibitor in the printed image inhibits photodecomposition of the specific lake pigment (fading inhibition step). As a result, fading of the printed image due to photodecomposition of the specific lake pigment in the water-based ink composition can be suppressed. That is, with the above method, it is possible to suppress fading caused by photodegradation of the printed image printed on the solid preparation by the inkjet method, and to maintain good visibility of the printed image. As a result, for example, when product information is printed on the surface of a solid lumber, dispensing errors, accidental ingestion, etc. can be prevented.

In one embodiment, the fading suppression step is based on the printed image on the solid preparation immediately after the printing step, and after the solid preparation after irradiation with visible light with an integrated light amount of 1.2 million lux, the printed image on the solid preparation is JIS Z The color difference ΔE ^* (ab) in the L ^* a ^* b ^* color system conforming to 8781 is preferably 17 or less (more preferably 9 or less).
In the above method, the monosaccharide preferably contains at least one of galactose and fructose.

In the above method, the disaccharide preferably contains at least one of maltose and trehalose.
In the above method, the dextrin preferably contains cyclodextrin.
In the above method, the sugar alcohol preferably contains at least one selected from the group consisting of reduced isomaltulose, xylitol and sorbitol.

One embodiment of the present invention also provides a solid formulation having a dry film of aqueous inkjet ink thereon. The water-based inkjet ink contains the water-based ink composition.
According to the above configuration, the fading inhibitor is contained in the dry film of the inkjet ink. As described above, the fading inhibitor suppresses photodecomposition of the specific lake pigment by light irradiation, so that fading of the printed image formed by the dry film can be reduced. As a result, deterioration in the visibility of the printed image can be suppressed. As a result, it is possible to provide a solid preparation capable of preventing dispensing errors, accidental ingestion, and the like.

According to the present invention, the discoloration inhibitor consisting of monosaccharides, disaccharides, dextrins and sugar alcohols reduces the discoloration of printed images caused by light irradiation of specific lake pigments containing dyes such as Red No. 2. be able to.
That is, according to the present invention, fading of printed images in solid formulations such as pharmaceuticals and foods can be suppressed. As a result, it is possible to provide an aqueous ink composition for inkjet, a method for suppressing fading of a printed image of a solid formulation, and a solid formulation, which are capable of improving the light resistance of printed images.

The above and further objects, features and effects of the present invention will be made clear by the following description of the embodiments.

(Aqueous ink composition for inkjet)
A water-based inkjet ink composition (hereinafter referred to as “aqueous ink composition”) according to one embodiment will be described below.
The water-based ink composition of the present embodiment is a water-based ink containing at least an edible lake pigment and a discoloration inhibitor, and having water as a main solvent. In addition, the aqueous ink composition of the present embodiment can have edibility by using materials that comply with the standards of pharmaceutical additives specified by the Pharmaceutical Affairs Law, the Japanese Pharmacopoeia, or the Japanese Code of Food Additives, and It can be suitably used for inkjet recording. Inkjet recording is an image recording method in which droplets of an aqueous ink composition are ejected from a fine inkjet head, and the droplets are fixed on a recording medium to form an image.

"Edible" of the lake pigment means that the substance is approved for oral administration as a drug or pharmaceutical additive, and/or is approved as a food or food additive.
The lake pigment is a specific dye containing at least one selected from the group consisting of Red No. 2, Red No. 3, Red No. 40, Red No. 102, Yellow No. 4, Yellow No. 5, Blue No. 1 and Blue No. 2. Contains lake pigments. In addition, the lake pigment may contain other lake pigments, if necessary, in addition to the specific lake pigment. Other lake pigments are not particularly limited as long as they are edible. A specific example is a lake pigment made of aluminum lake.

When the lake pigment constituting the aqueous ink composition is only the specific lake pigment, the content of the specific lake pigment is in the range of 0.5% to 12% by weight with respect to the total weight of the aqueous ink composition. more preferably in the range of 1% by mass to 5% by mass. When the content of the specific lake pigment is 0.5% by mass or more, it is possible to prevent the density of the printed image from becoming insufficient. When the content of the specific lake pigment is 12% by mass or less, it is possible to prevent ejection defects caused by deposition of the lake pigment component on the nozzles of the inkjet head.

Further, when the lake pigment constituting the water-based ink composition contains a lake pigment other than the specific lake pigment, the content of the other lake pigment can be appropriately set according to the type and the like.
The fading inhibitor has a function of suppressing photodecomposition of the specific lake pigment due to light irradiation such as natural light. Since the dyes contained in the constituent components of the specific lake pigment are photodecomposed by light irradiation, there is a risk that the printed image will be light-faded (discolored) if the specific lake pigment is used alone. However, the fading inhibitor inhibits photodegradation of such specific lake pigments, and thus can reduce fading of printed images.

The term “fading” means photodegradation of a specific lake pigment contained in a printed image under the influence of natural light or the like, which irreversibly changes the color tone of the printed image or deteriorates the printed image.
The discoloration inhibitor contains at least one selected from the group consisting of monosaccharides, disaccharides, dextrins and sugar alcohols.

Monosaccharides are not particularly limited, and specific examples include glucose, galactose, mannose, fructose and the like. Among these, galactose and fructose are preferred in the present embodiment.
Disaccharides are not particularly limited, and specific examples include sucrose (sucrose, sugar), lactose (milk sugar), maltose, trehalose, palatinose (isomaltulose), and the like. Among these, maltose and trehalose are preferred in the present embodiment.

Dextrin is not particularly limited, and specific examples thereof include cyclodextrin and the like. The cyclodextrin is not particularly limited, and specific examples include α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin and the like.
Sugar alcohols are not particularly limited, and specific examples include mannitol, erythritol, reduced isomaltulose, xylitol, sorbitol and the like. Furthermore, the reduced isomaltulose is a compound obtained by reducing isomaltulose by hydrogenation or the like. Reduced isomaltulose includes α-D-glucopyranosyl-1,1-mannitol (hereinafter referred to as “GPM”) and α-D-glucopyranosyl-1,6-sorbitol (hereinafter referred to as “GPS-6”). is a mixture of The mixing ratio of GPM and GPS-6 is not particularly limited, but they are usually mixed in approximately equimolar amounts. Among the sugar alcohols, reduced isomaltulose, xylitol and sorbitol are preferred in the present embodiment.

Each of the fading inhibitors exemplified above can be used singly or in combination of two or more.
The content of the anti-fading agent is 50% by mass or less, preferably 1% to 15% by mass, more preferably 5% to 10% by mass, based on the total mass of the aqueous ink composition. In particular, when dextrins or sugar alcohols are used as the fading inhibitor, the content thereof is preferably 20% by mass or less, preferably 1% to 15% by mass, based on the total mass of the aqueous ink composition. , more preferably 3% to 8% by mass. By setting the content of the fading inhibitor to 50% by mass or less, it is possible to prevent the fading inhibitor from precipitating in the water-based ink composition.

The water-based ink composition of this embodiment contains water (water as the main solvent). As water, it is preferable to use pure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, distilled water, or water from which ionic impurities are removed such as ultrapure water. In particular, water that has been sterilized by ultraviolet irradiation or the addition of hydrogen peroxide is suitable because it can prevent the growth of mold and bacteria over a long period of time. Moreover, the content of water is not particularly limited, and can be appropriately set as necessary.

Further, in the water-based ink composition of the present embodiment, other additives may be added as long as they conform to the standards of pharmaceutical additives specified by the Pharmaceutical Affairs Law, the Japanese Pharmacopoeia, or the Food Additives Standards. good. Examples of additives include surface tension modifiers, wetting agents, water-soluble resins, organic amines, surfactants, pH modifiers, chelating agents, preservatives, viscosity modifiers, antifoaming agents and the like. Except for the surface tension modifier and the wetting agent, the contents of these additives are not particularly limited, and can be appropriately set according to need. The contents of the surface tension modifier and the wetting agent will be described later.

Examples of surface tension modifiers are not particularly limited as long as they conform to standards such as the Pharmaceutical Affairs Law, and specific examples include glycerin fatty acid esters. Examples of glycerin fatty acid esters include decaglyceryl caprylate, hexaglyceryl laurate, hexaglycerol oleate, condensed tetraglyceryl linolenate, decaglyceryl laurate with an HLB (Hydrophilic-Lipophilic Balance) value of 15 or less, HLB decaglyceryl oleate having a value of less than 13, and the like. These may be used singly or in combination of two or more.

As decaglyceryl caprylate, it is possible to use a commercial product, and an example of such a commercial product is Ryoto (registered trademark) Polyglyester CE19D (trade name, manufactured by Mitsubishi Kagaku Foods Co., Ltd., HLB value 15 ), SY Glister MCA750 (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 16), and the like.
The HLB value is an HLB value according to Griffin's method, and is defined by the following formula.

HLB value = 20 x (sum of formula weights of hydrophilic groups/molecular weight)
The HLB value is a value within the range of 0 to 20. The larger the HLB value, the stronger the hydrophilicity, and the smaller the HLB value, the stronger the hydrophobicity.
Decaglyceryl laurate having an HLB value of 15 or less can be used. When decaglyceryl laurate having an HLB value exceeding 15 is used, the nozzles of the inkjet head are clogged, resulting in blurring and the like, resulting in a decrease in ejection stability. The lower limit of the HLB value is preferably 10 or more from the viewpoint of solubility in water solvents. As the decaglyceryl laurate having an HLB value of 15 or less, a commercially available product can be used. manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 14.5), SY Glister ML-750 (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 14.8).

Decaglyceryl oleate having an HLB value of less than 13 can be used. If the HLB value is 13 or more, the nozzles of the ink jet head are clogged, resulting in blurring and the like, and the ejection stability is lowered. The lower limit of the HLB value is preferably 10 or more from the viewpoint of solubility in water solvents. As decaglyceryl oleate having an HLB value of less than 13, it is possible to use a commercial product, and an example of such a commercial product is NIKKOL (registered trademark) DECAGLYN 1-OV (trade name, Nikko Chemicals Co., Ltd. manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 12), SY Glister MO-7S (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 12.9), and the like.

A commercially available product can be used as the lauric acid hexaglycerol ester, and an example of such a commercially available product is NIKKOL (registered trademark) HEXAGLYN 1-L (trade name, manufactured by Nikko Chemicals Co., Ltd., HLB value 14 .5), SY Glister ML-500 (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 13.5), and the like.
A commercially available product can be used as the oleic acid hexaglycerol ester, and an example of such a commercial product is SY Glister MO-5S (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 11.6). etc.

Commercially available products can be used as the condensed linolenic acid tetraglycerol ester, and examples of such commercial products include SY Glister CR-310 (trade name, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd.).
The content of the surface tension modifier is preferably in the range of 0.1% by mass to 10% by mass, more preferably in the range of 0.5% by mass to 5% by mass, relative to the total mass of the aqueous ink composition. It is more preferable to have When the content of the surface tension modifier is 0.1% by mass or more, when printing is performed by an inkjet method, ejection failure due to poor meniscus formation in the nozzle of the inkjet head is prevented, and clogging of the nozzle is prevented. can be prevented from occurring. As a result, ejection stability can be improved. On the other hand, when the content of the surface tension modifier is 10% by mass or less, it is possible to prevent adverse effects on ejection due to the insoluble matter of the surface tension modifier and poor emulsification.

The wetting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law, and specific examples thereof include propylene glycol and glycerin.
The amount of the humectant added is preferably 3% by mass to 50% by mass, more preferably 10% by mass to 40% by mass, relative to the total mass of the aqueous ink composition. By setting the content of the wetting agent to 3% by mass or more, clogging in the vicinity of the nozzles of the inkjet head can be prevented, and ejection performance can be further improved. On the other hand, by setting the content of the humectant to 50% by mass or less, the viscosity of the water-based ink composition can be appropriately controlled.

(Method for Suppressing Fading of Printed Image of Solid Formulation)
The method for suppressing fading of a printed image of a solid formulation of the present embodiment includes a preparation step of preparing an aqueous inkjet ink (hereinafter sometimes referred to as "aqueous ink") containing the aqueous ink composition described above, and It includes at least a printing step of inkjet-printing a solid formulation using a solid formulation, and a fading suppression step of suppressing fading of a printed image.

The water-based ink preparation step may include a water-based ink composition manufacturing step. In this case, the manufacturing process of the water-based ink composition can be carried out by mixing each of the components described above by an appropriate method. That is, the lake pigment, the anti-fading agent, water and, if necessary, additives are mixed and thoroughly stirred. Furthermore, filtration is performed to remove coarse particles and foreign matter that cause clogging as necessary. Thereby, the water-based ink composition according to the present embodiment can be obtained.

The method of mixing each material is not particularly limited, and for example, the materials can be sequentially added to a vessel equipped with a stirring device such as a mechanical stirrer or magnetic stirrer and stirred and mixed. Moreover, the filtration method is not particularly limited, and for example, centrifugal filtration, filter filtration, or the like can be employed.
The printing step is a step of printing an image on the surface of the solid preparation by an inkjet method. More specifically, water-based ink is ejected as ink droplets onto the solid preparation from fine nozzles, and the ink droplets adhere to the surface of the solid preparation to perform image printing. The ejection method is not particularly limited, and for example, a known method such as a continuous injection type (charge control type, spray type, etc.), an on-demand type (piezo method, thermal method, electrostatic attraction method, etc.) can be adopted. can. Printing conditions such as the ejection amount of ink droplets and the printing speed are not particularly limited, and can be appropriately set as required.

The printing process includes a drying process that dries the ink droplets adhered to the surface of the solid formulation. The drying method is not particularly limited, and other than hot air drying, natural drying and the like can be performed. Drying conditions such as drying time and drying temperature are not particularly limited, and can be appropriately set according to the ejection amount of ink droplets, the type of water-based ink composition, and the like.
The fading suppression step is a step of suppressing photodecomposition of the specific lake pigment due to light irradiation with a fading inhibitor contained in the printed image. For example, when the printed image on the surface of the solid preparation is irradiated with visible light (wavelength range 380 nm to 750 nm) with an integrated light amount of 1.2 million lux, the color change of the printed image is measured based on the printed image immediately after printing. ^* a ^* b ^* Color difference ΔE ^* (ab) in color system. The fading suppression step can suppress the color difference ΔE ^* (ab) to 17 or less, preferably 0 to 10, more preferably 0 to 5. By setting the color difference ΔE ^* (ab) to 17 or less, fading of the printed image can be reduced and good visibility can be maintained. As a result, when product information or the like is printed on the surface of the solid preparation, misidentification of the product information can be prevented, and the occurrence of dispensing errors and accidental ingestion can be reduced. A printed image immediately after printing means a printed image after drying, as described above.

ΔE ^* (ab) is a color difference according to JIS Z8781 and is represented by the following general formula (1). That is, ΔE ^* (ab) represents the change in color from the printed image immediately after printing.
ΔE ^* (ab) = ((ΔL ^* ₂ ) ² + (Δa ^* ₂ ) ² + (Δb ^* ₂ ) ² ) ^1/2 (1)
However, ΔL ^* ₂ , Δa ^* ₂ and Δb ^* ₂ are expressed as follows.
ΔL ^* ₂ =L ^* ₂ -L ^* ₀
L ^* ₀ represents the brightness of the L ^* a ^* b ^* color system immediately after the printing process in the printed image of the solid formulation, and L ^* ₂ represents the integrated light amount of the printed image of the solid formulation after irradiation with visible light of 1.2 million lux. represents the lightness of the L ^* a ^* b ^* color system.

Δa ^* ₂ = a ^* ₂ - a ^* ₀
a ^* ₀ represents the value of the L ^* a ^* b ^* color system immediately after the printing process in the printed image of the solid formulation, and a ^* ₂ represents the integrated amount of visible light of 1.2 million lux in the printed image of the solid formulation. represents the value of the L ^* a ^* b ^* color system after
Δb ^* ₂ = b ^* ₂ - b ^* ₀
b ^* ₀ represents the value of the L ^* a ^* b* color system immediately after the printing process in the printed image of the solid formulation, and b ^* ₂ represents the integrated amount of visible light of 1,200,000 lux in the printed image of the solid formulation. It represents the value of the later L ^* a ^* b ^* color system.

(Solid formulation)
As used herein, "solid formulation" is a term that includes food formulations and pharmaceutical formulations, and examples of forms of solid formulations include OD tablets (orally disintegrating tablets), uncoated tablets, and FC (film-coated) tablets. , tablets such as sugar-coated tablets, or capsules. Moreover, the solid formulation may be used for pharmaceuticals or food. Examples of tablets for food use include health foods such as candy tablets and supplements.

On the surface of the solid formulation, a printed image consisting of a dry film is formed by direct printing using an aqueous ink containing an aqueous ink composition by an inkjet recording method. The dry film is composed of at least the lake pigment and the anti-fading agent contained in the water-based ink composition.
In the solid preparation of the present embodiment, it is possible to reduce the fading of printed images made of dry films due to exposure to light such as natural light. Therefore, it is possible to prevent the deterioration of various information printed to improve identification for users, such as product information. Enable prevention.

Preferred embodiments of the present invention will be described in detail below. However, unless otherwise specified, the materials and contents described in the examples below do not limit the scope of the present invention. In addition, each material of the water-based ink composition for inkjet conforms to the standards for pharmaceutical additives defined by the Pharmaceutical Affairs Law, the Japanese Pharmacopoeia, or the Official Code of Food Additives.

(Example 1)
As shown in Table 1 below, a lake pigment made of 3.34% by mass of Blue No. 2 (dye) as a specific lake pigment (trade name: Blue No. 2 aluminum lake, manufactured by Daiwa Kasei Co., Ltd.), 5 mass as a fading inhibitor % reduced isomaltulose (trade name: Palatinit, manufactured by Mitsui Sugar Co., Ltd.), 1.66% by mass of polyglycerin fatty acid esters as a surface tension modifier (trade name: SY Glister, manufactured by Sakamoto Pharmaceutical Co., Ltd.), 25% by mass of propylene glycol as a wetting agent and 65% by mass of ion-exchanged water were mixed to prepare a blue water-based inkjet ink composition.

この実施例の水性インク組成物を用いて、インクジェット記録方法により、ＦＣ錠の一方の面に印刷を行った。印刷は、インクジェットプリンタ（ＰＸ－１０５、セイコーエプソン株式会社製）を用いてマルチパス方式にて行った。また、印刷は気温２５℃、相対湿度４０％の環境下で行った。その後、ドライヤーにて熱風を直接当て、印刷面を十分に乾燥させた。

Using the water-based ink composition of this example, printing was performed on one side of an FC tablet by an inkjet recording method. Printing was performed by a multi-pass method using an inkjet printer (PX-105, manufactured by Seiko Epson Corporation). Further, printing was performed under an environment of 25° C. temperature and 40% relative humidity. After that, hot air was directly applied with a dryer to sufficiently dry the printed surface.

(Comparative example 1)
The water-based ink composition used as Comparative Example 1 was as shown in Table 1 above.
Furthermore, using the water-based ink composition of Comparative Example 1, printing was performed on FC tablets by an inkjet recording method in the same manner as in the above-described Examples. Thus, a sample of Comparative Example 1 was produced.

(Evaluation on photofading suppression)
The anti-fading properties of the water-based ink compositions in the samples of Example 1 and Comparative Example 1 were evaluated by conducting the following tests. That is, for the FC tablets (samples) after inkjet printing with the water-based ink compositions according to Example 1 and Comparative Example 1, L ^* L ^* ₀ , a ^* ₀ , and b ^* ₀ in the a ^* b ^* color system were measured. These correspond to the values of L ^* , a ^* , and b ^* at an integrated light amount of 0 lux in Table 2 below, which shows the measurement results.

Subsequently, after printing stored in a sealed glass bottle using a photostability tester (manufactured by Nagano Science Co., Ltd.) in accordance with the guidelines of ICH (International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use) The sample was irradiated with light. The integrated amount of light at this time was 300,000 lux, 600,000 lux, and 1,200,000 lux (1,200,000 lux is for 50 days in terms of indoor fluorescent lighting). After that, using the color difference meter again, L ^* ₂ , a ^* ₂ , and b ^* ₂ in the L ^* a ^* b ^* color system of each sample were measured. These correspond to the values of L ^* , a ^* , and b ^* at integrated light intensities of 300,000 lux, 600,000 lux, and 1,200,000 lux, respectively, in Table 2 below showing the measurement results.

Color difference ΔE ^* (ab) ₂ , lightness difference ΔL ^* ₂ , chromaticity difference Δa ^* ₂ and Δb ^* ₂ , chroma difference ΔC ^* (ab) ₂ , and hue difference ΔH ^* (ab) ₂ shown in each table are , respectively calculated by the following general formulas (2) to (7).
ΔE ^* (ab) ₂ = ((ΔL ^* ₂ ) ² + (Δa ^* ₂ ) ² + (Δb ^* ₂ ) ² ) ^1/2 (2)
ΔL ^* ₂ =L ^* ₂ -L ^* ₀ (3)
Δa ^* ₂ = a ^* ₂ - a ^* ₀ (4)
Δb ^* ₂ =b ^* ₂ -b ^* ₀ (5)
ΔC ^* (ab) ₂ = ((Δa ^* ₂ ) ² + (Δb ^* ₂ ) ² ) ^1/2 (6)
ΔH ^* (ab) ₂ = (ΔE ^* (ab) ₂ ² - ΔL ^* ₂ ² - ΔC ^* (ab) ₂ ² ) ^1/2 (7)

（結果）
表２に示す通り、比較例１のサンプルにおいては、色差ΔＥ^*(ab)₂が、印刷直後と比較していずれも大きくなり、印刷画像が大幅に光褪色していることが確認された。その一方、実施例１のサンプルにおいては、ＦＣ錠に印刷された印刷画像の色差ΔＥ^*(ab)₂の増加が大幅に抑制され、全て９以下（より具体的には５以下、詳細には３以下、より詳細には１．５以下、さらに詳細には１．２以下）となった。これにより、実施例１においては、印刷画像中のレーキ顔料の構成成分である青色２号（染料）の光分解を低減することができ、褪色の低減が可能であることが確認された。

(result)
As shown in Table 2, in the samples of Comparative Example 1, the color difference ΔE ^* (ab) ₂ was larger than immediately after printing, and it was confirmed that the printed image was significantly faded. On the other hand, in the sample of Example 1, the increase in the color difference ΔE ^* (ab) ₂ of the printed image printed on the FC tablet was greatly suppressed, and all of them were 9 or less (more specifically 5 or less, more specifically 3 or less, more specifically 1.5 or less, more specifically 1.2 or less). Thus, in Example 1, it was confirmed that the photodecomposition of Blue No. 2 (dye), which is a component of the lake pigment in the printed image, can be reduced, and that fading can be reduced.

(Example 2)
As shown in Table 3, a lake pigment made of 8% by weight of Yellow No. 4 (dye) as a specific lake pigment (trade name: Yellow No. 4 aluminum lake, manufactured by Daiwa Kasei Co., Ltd.), 1% by weight of poly as a pigment dispersant Sodium acrylate (trade name: TEGO (registered trademark) Dispers 715W, manufactured by Evonik, weight average molecular weight 3000), 1% by weight disodium malate (manufactured by Wako Pure Chemical Industries, Ltd.) as a dispersion stabilizer, and a dispersion medium 50% by mass of ion-exchanged water was mixed in a container, and the mixed solution was dispersed with a dispersing machine (paint shaker, manufactured by Asada Iron Works Co., Ltd.) to prepare a dispersion of a specific lake pigment. Subsequently, the prepared specific lake pigment dispersion liquid contains 12% by mass of reduced isomaltulose (trade name: Palatinit, manufactured by Mitsui Sugar Co., Ltd.) as a discoloration inhibitor, 15% by mass of propylene glycol as a wetting agent, and the surface 2% by mass of decaglyceryl monocaprylate (trade name: SY Glister MCA750, manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., HLB value 16) is added as a tension adjusting agent, and 11% by mass of deionized water is added and mixed, A yellow aqueous ink composition for inkjet was prepared.

(Example 3)
As shown in Table 3, the discoloration inhibitor was changed to galactose (manufactured by Wako Pure Chemical Industries, Ltd.), and the rest was the same as in Example 2.
(Example 4)
As shown in Table 3, the discoloration inhibitor was changed to maltose (manufactured by Wako Pure Chemical Industries, Ltd.), and the rest was the same as in Example 2.

(Comparative example 2)
As shown in Table 3, the total content of ion-exchanged water was 73% by mass without adding a discoloration inhibitor, and the rest was the same as in Example 2.

（結果）
前述の実施例１及び比較例１の場合と同様に、それぞれの水性インク組成物を用いて、インクジェット記録方法により、素錠の一方の面に印刷を行い、その後、印刷面を充分に乾燥させた。そして、水性インク組成物の褪色抑制性について、実施例１及び比較例１の場合と同様の試験を行って評価した。下記の表４は、積算光量１２０万ｌｕｘでのＬ^＊、ａ^＊、ｂ^＊の測定値に対応する測定結果を示す。

(result)
In the same manner as in Example 1 and Comparative Example 1 described above, each aqueous ink composition was used to print on one side of the uncoated tablet by an inkjet recording method, and then the printed surface was sufficiently dried. rice field. Then, the same test as in Example 1 and Comparative Example 1 was conducted to evaluate the anti-fading property of the water-based ink composition. Table 4 below shows measurement results corresponding to the measured values of L ^* , a ^* , and b ^* at an integrated light intensity of 1,200,000 lux.

表４に示す通り、比較例２のサンプルにおいては、色差ΔＥ^*(ab)₂が、印刷直後と比較して大きくなり、印刷画像が大幅に光褪色していることが確認された。その一方、実施例２～４のサンプルにおいては、素錠に印刷された印刷画像の色差ΔＥ^*(ab)₂の増加が大幅に抑制され、全て９以下（より具体的には５以下、詳細には３以下）となった。これにより、実施例２～４においては、印刷画像中のレーキ顔料の構成成分である黄色４号（染料）の光分解を低減することができ、褪色の低減が可能であることが確認された。

As shown in Table 4, in the sample of Comparative Example 2, the color difference ΔE ^* (ab) ₂ was larger than immediately after printing, and it was confirmed that the printed image was significantly faded. On the other hand, in the samples of Examples 2 to 4, the increase in the color difference ΔE ^* (ab) ₂ of the printed image printed on the uncoated tablets was greatly suppressed, and all of them were 9 or less (more specifically, 5 or less; 3 or less). As a result, in Examples 2 to 4, it was confirmed that photodegradation of Yellow No. 4 (dye), which is a component of the lake pigment in the printed image, can be reduced, and that fading can be reduced. .

(Example 5)
As shown in Table 5, the specific lake pigment was changed to a lake pigment made of Red No. 102 (trade name: Red No. 102 aluminum lake, manufactured by Daiwa Kasei Co., Ltd.) to prepare a red water-based inkjet ink. The rest was the same as in Example 2.
(Example 6)
As shown in Table 5, the discoloration inhibitor was changed to galactose (manufactured by Wako Pure Chemical Industries, Ltd.), and the rest was the same as in Example 5.

(Example 7)
As shown in Table 5, the discoloration inhibitor was changed to maltose (manufactured by Wako Pure Chemical Industries, Ltd.), and the rest was the same as in Example 5.
(Comparative Example 3)
As shown in Table 5, the total content of ion-exchanged water was 73% by mass without adding a discoloration inhibitor. The rest was the same as in Example 5.

（結果）
前述の実施例１及び比較例１の場合と同様に、それぞれの水性インク組成物を用いて、インクジェット記録方法により、素錠の一方の面に印刷を行い、その後、印刷面を充分に乾燥させた。そして、水性インク組成物の褪色抑制性について、実施例１及び比較例１の場合と同様の試験を行って評価した。下記の表６は、積算光量１２０万ｌｕｘでのＬ^＊、ａ^＊、ｂ^＊の測定値に対応する測定結果を示す。

(result)
In the same manner as in Example 1 and Comparative Example 1 described above, each aqueous ink composition was used to print on one side of the uncoated tablet by an inkjet recording method, and then the printed surface was sufficiently dried. rice field. Then, the same test as in Example 1 and Comparative Example 1 was conducted to evaluate the anti-fading property of the water-based ink composition. Table 6 below shows measurement results corresponding to the measured values of L ^* , a ^* , and b ^* at an integrated light intensity of 1,200,000 lux.

表６に示す通り、比較例３のサンプルにおいては、色差ΔＥ^*(ab)₂が、印刷直後と比較して大きくなり、印刷画像が大幅に光褪色していることが確認された。その一方、実施例５～７のサンプルにおいては、素錠に印刷された印刷画像の色差ΔＥ^*(ab)₂の増加が大幅に抑制され、全て９以下（より具体的には７．５以下）となった。これにより、実施例５～７においては、印刷画像中のレーキ顔料の構成成分である赤色１０２号（染料）の光分解を低減することができ、褪色の低減が可能であることが確認された。

As shown in Table 6, in the sample of Comparative Example 3, the color difference ΔE ^* (ab) ₂ was larger than that immediately after printing, and it was confirmed that the printed image was greatly faded by light. On the other hand, in the samples of Examples 5 to 7, the increase in the color difference ΔE ^* (ab) ₂ of the printed image printed on the uncoated tablet was greatly suppressed, and all of them were 9 or less (more specifically, 7.5 or less). ). As a result, in Examples 5 to 7, it was confirmed that the photodecomposition of Red No. 102 (dye), which is a component of the lake pigment in the printed image, can be reduced, and that fading can be reduced. .

Blue No. 2, Yellow No. 4 and Red No. 102 dyes shown in Examples 1-7 above, as well as Red No. 2, Red No. 3, Red No. 40, Red No. 102, Yellow No. 4, Yellow No. 5 , Blue No.1 and Blue No.2. In addition to these specific lake pigments, even if the lake pigment contains other lake pigments, such as aluminum lake pigments, as an optional component, it is known to those skilled in the art that the same discoloration suppressing effect can be obtained with respect to the specific lake pigment. is self-evident.

The content of the anti-fading agent was 5% by mass in the above-described example samples, but it was confirmed that a content of up to 50% by mass could be dissolved without causing precipitation. Therefore, if it is 50% by mass or less, it is possible to achieve a discoloration suppressing effect equal to or greater than that of the above examples. As for the lower limit of the content, it has been confirmed that a similar discoloration suppressing effect can be obtained if the content is 0.5% by mass or more. If the content of the fading inhibitor is 1% by mass to 15% by mass (more preferably 5% by mass to 10% by mass), problems such as nozzle clogging can be suppressed.

Although the embodiments of the present invention have been described in detail, these are merely specific examples used to clarify the technical content of the present invention, and the present invention should be construed as being limited to these specific examples. should not, the scope of the invention is limited only by the appended claims.

Claims (4)

An inkjet aqueous ink composition used for printing on a solid formulation,
Containing an edible lake pigment and a fading inhibitor,
The lake pigment comprises a dye containing at least one selected from the group consisting of Red No. 2, Red No. 3, Red No. 40, Red No. 102, Yellow No. 4, Yellow No. 5, Blue No. 1 and Blue No. 2. Contains specific lake pigments,
The discoloration inhibitor contains reduced isomaltulose ,
A water-based ink composition for inkjet, wherein the content of the discoloration inhibitor is 1% by mass to 15% by mass with respect to the total mass of the water-based ink composition. A method for suppressing fading of a printed image printed on a solid preparation,
A preparatory step of preparing an aqueous inkjet ink comprising an aqueous inkjet ink composition, wherein the aqueous inkjet ink composition comprises an edible lake pigment and a fading inhibitor, and the lake pigment is red. 2, Red No. 3, Red No. 40, Red No. 102, Yellow No. 4, Yellow No. 5, Blue No. 1 and Blue No. 2 containing at least one dye selected from the group consisting of a specific lake pigment, a step in which the anti-fading agent contains reduced isomaltulose , and the content of the anti-fading agent is 1% by mass to 15% by mass with respect to the total mass of the water-based ink composition;
A printing step of forming the printed image on the surface of the solid formulation by an inkjet method using the aqueous inkjet ink;
A fading suppression step in which the fading inhibitor in the printed image suppresses photodecomposition of the specific lake pigment;
A method for suppressing fading of a printed image of a solid formulation containing. In the fading suppression step, based on the printed image on the solid preparation immediately after the printing step, the printed image on the solid preparation after irradiation with visible light having an integrated light amount of 1.2 million lux, L ^* a ^* in accordance with JIS Z 8781. The method for suppressing fading of printed images of solid preparations according to claim 2 , wherein the color difference ΔE ^* (ab) in the b ^* color system is set to 9 or less. A solid preparation having a dry film of aqueous inkjet ink on its surface,
The aqueous inkjet ink is a solid formulation comprising the aqueous inkjet ink composition according to claim 1 .