JP2017165862A - Aqueous ink composition for inkjet, manufacturing method therefor and solid formulation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous ink composition for inkjet capable of direct printing to solid formulations such as pharmaceuticals and foods by an inkjet method, having edibility and using a dye exhibiting poor solubility to water, a manufacturing method therefor and the solid formulations.SOLUTION: The aqueous ink composition for inkjet is an aqueous ink composition for inkjet used in inkjet recording, contains at least water, a dye exhibiting poor solubility to the water and urine as a solubilizer for solubilizing the dye to the water, the content of the urine is in a range of 10 mass% to 40 mass% based on all mass of the aqueous ink composition for inkjet.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous inkjet ink composition, a method for producing the same, and a solid preparation. More specifically, the present invention directly prints on tablets of pharmaceuticals, foods, and the like using a dye that is sparingly soluble in water. It is related with the edible water-based ink composition for inkjet, its manufacturing method, and a solid formulation.

  For foods such as pharmaceuticals and supplements in tablets, product information is displayed not only on the package but also on the tablet body, thereby improving their distinguishability and preventing dispensing errors and accidental ingestion. Tablets with a coated surface can be printed by a contact method such as gravure printing, so information with high discrimination is displayed on the one hand, but uncoated or OD (orally disintegrating) tablets with poor surface smoothness are in contact. Printing by the method is difficult. Therefore, for these tablets, a marking method that can display only simple characters has become the mainstream. As a result, there is an increasing need for a new printing method capable of displaying highly discriminating information even for uncoated tablets and OD tablets.

  However, it is difficult to use a conventional aqueous ink composition for direct printing on tablets or the like. For example, an aqueous inkjet ink composition using a pigment such as a dye (hereinafter referred to as “aqueous ink composition”). )), It is necessary to use a material that complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. However, some dyes are excellent in light resistance, color development, etc., but due to their low solubility in water, the concentration has to be lowered, and as a result, there are some that are difficult to ensure sufficient discrimination. . In particular, as blue-based synthetic food dyes, there are only food blue No. 1 and food blue No. 2 showing poor solubility in water in Japan. Moreover, the food blue No. 1 has a problem that the light resistance is not sufficient.

JP 2011-236279 A

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to enable direct printing in an ink jet system for solid preparations such as pharmaceuticals and foods, to be edible, and to be difficult against water. An object of the present invention is to provide a water-based ink composition for inkjet using a dye having solubility, a method for producing the same, and a solid preparation.

  In order to solve the above problems, the inventors of the present application have studied an aqueous inkjet ink composition, a method for producing the same, and a solid preparation. As a result, the inventors have found that the above problems can be solved by adopting the following configuration, and have completed the present invention.

  That is, the aqueous ink composition for ink jet according to the present invention is an aqueous ink composition for ink jet used for ink jet recording in order to solve the above-mentioned problems, and includes water and a dye that is hardly soluble in the water. And urea as a solubilizer that solubilizes the dye in water, and the urea content is in the range of 10% by mass to 40% by mass with respect to the total mass of the aqueous ink composition for inkjet. In addition, when a surface tension adjusting agent and / or wetting agent is included, the urea content is 20 times or more on a mass basis with respect to the dye content, and the surface tension adjusting agent and the wetting material are included. If not, the urea content is 5 times or more on a mass basis with respect to the dye content.

  In the present invention, by containing urea, the hydrogen bond of water molecules contained in the water-based ink composition for ink jet is weakened, thereby increasing the solubility in water of a dye that is hardly soluble in water. As a result, for example, although it is excellent in light resistance and color development, it can be applied to dyes that are difficult to use because of low solubility in water, and the range of dye selection can be expanded.

  Here, in the present invention, when the urea content is in the range of 10% by mass to 40% by mass with respect to the total mass of the aqueous inkjet ink composition, and the surface tension adjusting agent and / or wetting agent is included. The urea content is 20 times or more on the mass basis with respect to the dye content, and 5 times or more when the surface tension adjusting agent or the like is not included. This enables solubilization of the dye and prevents urea from being oversaturated and precipitated. In addition, since urea contained as a solubilizing agent also meets the standards for pharmaceutical additives stipulated by the Pharmaceutical Affairs Law, the aqueous inkjet ink composition of the present invention is directly printed on tablets such as pharmaceuticals and foods. It is also possible.

  The “inkjet recording” means a system in which an aqueous inkjet ink composition is ejected as droplets from a fine inkjet head, the droplets are fixed on a recording medium, and an image is formed. It is not limited to paper or the like, and includes solid preparations such as pharmaceuticals and foods.

  In the above configuration, the dye may be Red No. 2 or Blue No. 2. Since these dyes have low solubility in water, it has been difficult to contain a sufficient amount when used in an aqueous inkjet ink composition. However, the aqueous inkjet ink composition of the present invention contains urea that solubilizes these dyes in water, and therefore can be sufficiently dissolved. As a result, it is possible to provide an aqueous inkjet ink composition that enables image printing with excellent light resistance and color developability.

  Moreover, it is preferable that the water-based ink composition for inkjet according to the present invention has edible properties. Here, the term “edible” means that the substance consists only of substances that are approved for oral administration as pharmaceuticals or pharmaceutical additives and / or substances that are recognized as foods or food additives.

  A method for producing an aqueous inkjet ink composition according to the present invention is a method for producing an aqueous inkjet ink composition for producing the aqueous inkjet ink composition described above, in order to solve the above problems. Adding urea as the solubilizer to the water, returning the temperature of the water after the urea addition to room temperature, optionally adding a wetting agent and / or a surface tension adjusting agent to the water; The dye is added to water containing urea whose water temperature is returned to room temperature, and the urea content is 10% by mass to 40% with respect to the total mass of the water-based ink composition for inkjet. When the surface tension adjusting agent and / or wetting agent is added in the range of mass%, the urea content is 20 times or more on a mass basis with respect to the dye content, and the surface tension adjustment is performed. If and without the addition of a wetting agent is characterized by comprising the step of the content of the urea as a by weight 5 times or more relative to the content of said dye.

  In the said structure, first, urea which is a solubilizer is added to water. At this time, the temperature of water falls due to the heat of dissolution due to the addition of urea. Therefore, before adding a dye, the process which returns the temperature of water to normal temperature is performed. This prevents the solubility of the dye from decreasing and makes it difficult to add a dye having a desired concentration. In addition, in the dye addition step, the urea content is set in the range of 10% by mass to 40% by mass with respect to the total mass of the inkjet ink composition. Further, when a surface tension adjusting agent and / or a wetting agent is added, the dye content is 20 times or more on a mass basis, and when the surface tension adjusting agent or the like is not added, the surface tension adjusting agent and / or wetting agent is 5 times or more. Add to. This makes it possible to solubilize a dye that is sparingly soluble in water and to prevent the urea from becoming supersaturated and precipitating. Urea contained as a solubilizer also conforms to the standards for pharmaceutical additives stipulated by the Pharmaceutical Affairs Law, and according to the above configuration, it can be directly printed on tablets such as pharmaceuticals and foods. An aqueous ink composition for inkjet can be produced.

  In order to solve the above problems, a solid preparation according to the present invention is a solid preparation comprising a tablet or a capsule and having a dry film of an aqueous inkjet ink on the surface, wherein the inkjet aqueous ink is It consists of the water-based ink composition for inkjet.

  As described above, the water-based ink composition for inkjet contains urea as a solubilizing agent, so that it is difficult to use dyes that have been difficult to use in the past. Dissolution in an aqueous ink composition is possible. The dry film provided on the surface of the solid preparation is formed by directly printing an inkjet aqueous ink comprising the inkjet aqueous ink composition by an inkjet recording method. Therefore, it is possible to display product information on the solid preparation body using a dye that has been difficult to use. For example, when using a dye having excellent light resistance, color developability, etc. such as Blue No. 2, it is possible to provide a tablet capable of improving discrimination and improving prevention of dispensing mistakes and accidental ingestion compared to the past. it can. The solid preparation of the present invention is meant to include food preparations and pharmaceutical preparations.

  According to the present invention, urea as a solubilizing agent is in the range of 10% by mass to 40% by mass with respect to the total mass of the aqueous inkjet ink composition, and includes a surface tension adjusting agent and / or a wetting agent. In this case, the dye is contained so as to be 20 times or more on the mass basis and 5 times or more when the surface tension adjusting agent is not included. Thereby, conventionally, it is possible to apply a dye, which has been difficult to use due to poor solubility in water, to an aqueous inkjet ink composition. Urea as a solubilizer complies with the standards for pharmaceutical additives stipulated by the Pharmaceutical Affairs Law, so the aqueous inkjet ink composition of the present invention can be directly printed on tablets such as pharmaceuticals and foods. It is possible.

  That is, according to the present invention, an ink-jet aqueous ink composition using a dye that can be directly printed on tablets or the like of pharmaceuticals and foods, is edible, and hardly soluble in water, Manufacturing methods and solid formulations can be provided.

(Water-based ink composition for inkjet and production method thereof)
The ink-jet aqueous ink composition (hereinafter referred to as “water-based ink composition”) according to the present embodiment will be described below.
The water-based ink composition of the present embodiment includes a water-based ink containing at least a dye that is hardly soluble in water and urea as a solubilizer that solubilizes the dye in water, and the main solvent is water. It is. In addition, the water-based ink composition of the present embodiment may be made edible by using a material that complies with the standards of pharmaceutical additives, Japanese Pharmacopoeia, or Food Additives Standards specified by the Pharmaceutical Affairs Law. And can be suitably used for inkjet recording.

  It does not specifically limit as a dye which shows the poor solubility with respect to the said water, For example, red No. 2, blue No. 2, etc. are mentioned. Blue No. 2 conforms to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law, and is superior in light resistance to Blue No. 1. Therefore, when Blue No. 2 is used as a dye, it is possible to provide an aqueous ink composition that enables a printed image having excellent light resistance and color developability. Here, the “slightly soluble” means that the solubility of the dye in water at 30 ° C. is less than 2 g / 100 g. The solubility value is the same for 30 ° C. propylene glycol.

  In the present embodiment, other dyes may be used in combination. Such other dyes are not particularly limited, and examples thereof include azo dyes, triphenylmethane dyes, and xanthene dyes. The azo dye is not particularly limited, and examples thereof include Red No. 102, Red No. 40, Yellow No. 4, Yellow No. 5, and the like. The triphenylmethane dye is not particularly limited, and examples thereof include blue No. 1 and green No. 3. The xanthene dye is not particularly limited, and examples thereof include Red No. 3, Red No. 104, Red No. 105, and Red No. 106. Furthermore, it is also possible to use edible natural pigments such as cochineal pigment, copper chlorophyllin sodium, cacao pigment and caramel pigment together. These dyes comply with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. Furthermore, the permeability with respect to the solid formulation which consists of a tablet and a capsule is favorable compared with another dye.

  The content of the dye exhibiting poor solubility in water is preferably in the range of 0.5% by mass to 5% by mass with respect to the total mass of the aqueous ink composition, and in the range of 1% by mass to 3% by mass. More preferably, it is within. By setting the dye content to 0.5% by mass or more, it is possible to prevent the density of the printed image from becoming insufficient with many dyes. On the other hand, by setting the content of the dye to 5% by mass or less, it is possible to prevent the dye component from being deposited in the nozzle of the inkjet head.

  Urea as the solubilizer is an additive that solubilizes the dye, which is sparingly soluble in water, by weakening the hydrogen bonds of water molecules in the aqueous ink composition, thereby improving its solubility.

  The urea content is in the range of 10% by mass to 40% by mass with respect to the total mass of the aqueous ink composition, preferably 15% by mass to 35% by mass, and more preferably 20% by mass to 30% by mass. . Furthermore, the urea content is 20 times or more, preferably 25 times or more, on a mass basis with respect to the dye content when it contains a surface tension adjusting agent and / or wetting agent described later. When the surface tension adjusting agent and the wetting agent are not included, the content is 5 times or more, preferably 10 times or more, more preferably 15 times or more, based on the mass of the dye. When the urea content is within the numerical range, the solubility of dyes that are hardly soluble in water can be sufficiently improved. Moreover, it can prevent that urea content becomes excessive and precipitates.

  The water-based ink composition according to this embodiment contains water (water as a main solvent). As the water, it is preferable to use water from which ionic impurities such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water have been removed. In particular, water sterilized by ultraviolet irradiation or the like is preferable because generation of mold and bacteria can be prevented over a long period of time. Moreover, it does not specifically limit as content of water, It can set suitably as needed.

  The aqueous ink composition of the present embodiment may contain a wetting agent. The wetting agent is not particularly limited as long as it meets standards such as the Pharmaceutical Affairs Law, and specific examples include propylene glycol and glycerin.

  The addition amount of the wetting agent is preferably 15% by mass to 30% by mass with respect to the total mass of the aqueous ink composition. Since urea itself has a certain moisturizing power, the amount of the wetting agent added can be less than that of a general water-based ink composition for inkjet. By setting the content of the wetting agent to 15% by mass or more, clogging in the vicinity of the nozzle of the inkjet head can be prevented, and the discharge performance can be improved. On the other hand, by setting the content of the wetting agent to 30% by mass or less, it is possible to ensure the solubility of the dye while appropriately controlling the viscosity of the aqueous ink composition.

  In the aqueous ink composition of the present embodiment, other additives may be blended. However, when used as an ink-jet ink for solid preparations such as pharmaceuticals, it is preferably one that complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. Examples of the additive include a surface tension adjusting agent, a water-soluble resin, an organic amine, a surfactant, a pH adjusting agent, a chelating agent, an antiseptic, a viscosity adjusting agent, and an antifoaming agent. The content of these additives is not particularly limited, and can be appropriately set as necessary.

  The surface tension adjusting agent means an additive containing a compound having a function of reducing the surface tension of the aqueous ink composition. The surface tension adjusting agent is not particularly limited, and examples thereof include caprylic acid decaglyceryl, lauric acid hexaglycerin ester, oleic acid hexaglycerin ester, condensed linolenic acid tetraglycerin ester, fatty acid ester palm palm, lauric acid decaglyceryl, and oleic acid. Decaglyceryl and the like can be used.

  A commercially available product can be used as the decaglyceryl caprylate. Examples of such a commercially available product include Ryoto (registered trademark) polyglycerate CE19D (trade name, manufactured by Mitsubishi Chemical Foods Corporation, HLB value 15 ), SY Grister MCA750 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd., HLB value 16), and the like. As said decaglyceryl laurate, it is possible to use a commercial item, and as such a commercial item, for example, NIKKOL (registered trademark) DECAGLYN 1-L (trade name, manufactured by Nikko Chemicals Co., Ltd., HLB value) 14.5), SY Glister ML-750 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd., HLB value 14.8), and the like.

  Commercially available products can be used as the decaglyceryl oleate. Examples of such commercially available products include NIKKOL (registered trademark) DECAGLYN 1-OV (trade name, manufactured by Nikko Chemicals Co., Ltd., HLB value 12). SY Glister MO-7S (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd., HLB value 12.9), and the like.

  As the lauric acid hexaglycerin ester, a commercially available product can be used. Examples of such a commercially available product include 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 Pharmaceutical Co., Ltd., HLB value 13.5), and the like.

  Commercially available products can be used as the oleic acid hexaglycerin ester. Examples of such commercially available products include SY Glyster MO-5S (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd., HLB value 11.6). Etc.

  A commercially available product can be used as the condensed linolenic acid tetraglycerin ester, and examples of such a commercially available product include SY Glyster CR-310 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd.).

  As the fatty acid ester palm palm, a commercially available product can be used, and examples of such a commercially available product include Tirabazole W-01 (trade name, manufactured by Taiyo Kagaku Co., Ltd.).

The HLB value is an HLB value according to the Griffin method and means a value obtained by the following equation.
HLB value = 20 × (sum of formula weight of hydrophilic group / molecular weight)
The HLB value is a value in 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.

  The content of the surface tension adjusting agent is preferably in the range of 0.5% by mass to 5% by mass and preferably in the range of 1% by mass to 3% by mass with respect to the total mass of the aqueous ink composition. Is more preferable. When the content of the surface tension adjusting agent is 0.5% by mass or more, when printing is performed by an inkjet method, ejection failure due to poor meniscus surface formation at the nozzle in the inkjet head is prevented, and It is possible to prevent clogging and blurring of the printed image. As a result, the discharge stability can be improved. On the other hand, when the content of the surface tension adjusting agent is 5% by mass or less, it is possible to prevent an adverse effect on discharge due to insoluble matter or poor emulsification of the surface tension adjusting agent.

  The method for producing the water-based ink composition of the present embodiment includes a step of adding urea as a solubilizer to water, a step of returning the temperature of water after addition of urea to room temperature, a wetting agent and / or a surface of water. A step of optionally adding a tension adjusting agent and a step of adding a dye to water containing the urea whose water temperature is returned to room temperature are included.

  In the present embodiment, urea is first added to water, which is the main solvent, and then the temperature of the water is returned to room temperature because of the heat of dissolution due to the addition of the urea. By considering That is, when urea is added to water to which a dye has been added in advance, the solubility decreases due to a decrease in the temperature of the water, and it becomes difficult to dissolve a dye having a desired concentration.

  After returning the temperature of the water to which urea has been added to room temperature, the dye is added. The content of the dye is in the range of 10% by mass to 40% by mass, preferably 15% by mass to 35% by mass, and more preferably 20% by mass to 30% by mass with respect to the total mass of the aqueous inkjet ink composition to be produced. % By mass. Further, when a surface tension adjusting agent and / or a wetting agent is added, the dye is added so that the urea content is 20 times or more, preferably 25 times or more, based on the mass of the dye. . On the other hand, when the surface tension adjusting agent and the wetting agent are not added, the urea content is 5 times or more, preferably 10 times or more, more preferably 15 times or more, based on the mass of the dye. Dye is added.

  The addition of the wetting agent and / or the surface tension adjusting agent is appropriately performed as necessary, and is an optional step. Moreover, it does not specifically limit about the order which implements the said process, For example, you may carry out with respect to the water after urea addition. Moreover, you may carry out after addition of dye.

  The mixing method of each material is not particularly limited, and for example, the materials can be sequentially added to a container equipped with a stirring device such as a disper, a mechanical stirrer, or a magnetic stirrer to perform stirring and mixing. Moreover, it does not specifically limit as a filtration method, For example, centrifugal filtration, filter filtration, etc. are employable.

  The aqueous ink composition of the present embodiment can be applied to ink and paint. In addition, since the water-based ink composition of the present embodiment can use a dye that is sparingly soluble in water, it has been difficult to use because of its poor water solubility, such as light resistance and color development. The dyes such as Blue No. 2 which are excellent in color can also be suitably used. In particular, the water-based ink composition of the present embodiment uses edible substances because urea and dyes conforming to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law, etc. are used. It is possible to print directly on the surface of a solid agent comprising tablets or capsules such as pharmaceuticals or supplements. In addition, non-contact printing by an ink jet method is possible even for tablets with poor surface smoothness such as uncoated tablets and OD tablets.

(Solid preparation)
The solid preparation of the present embodiment is composed of a tablet or a capsule, and the surface of the solid agent is directly printed by an inkjet recording method using an inkjet aqueous ink composed of the aqueous ink composition. is there. As described above, since the water-based ink composition can use a dye that has been difficult to use due to poor solubility in water, printing with excellent light resistance and color developability can be achieved by selecting an optimal dye. Enable images. As a result, various information for improving the user's identification, such as product information, can be printed on the solid preparation, and dispensing errors and accidental ingestion can be prevented.

  Tablets are solid at room temperature, and for example, tablets produced by compressing and / or molding a tablet material containing an active ingredient into a certain shape are preferable. The capsule is preferably prepared by filling a powder, granule, liquid or the like in a capsule made of gelatin, cellulose derivative or the like, or encapsulating with a capsule base. The shape of a tablet and a capsule is not specifically limited, Arbitrary shapes can be employ | adopted. Tablets and capsules may be used for pharmaceuticals or foods. Examples of tablets for food use include health foods such as tablet confectionery and supplements.

  The ink jet recording method for the surface of the solid preparation is not particularly limited. Specifically, for example, the water-based ink composition can be discharged as droplets from a fine nozzle, and the droplets can be attached to the surface of the solid preparation. The discharge 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 type, thermal type, electrostatic suction type, etc.) can be employed. .

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, materials, contents, and the like described in the following examples are not intended to limit the scope of the present invention only to those unless otherwise specified.

(Examples 1-3)
In Examples 1 to 3, Blue No. 2 was used as a dye, and urea (pharmaceutical grade of Japanese Pharmacopoeia) was used as a solubilizer. The water-based ink composition of each example was prepared by placing it in a container so as to have the composition shown in Table 1 and stirring with a disper.

  The numerical values in Table 1 below are all expressed in mass% unless otherwise specified. The same applies to numerical values in other tables described later. Each material complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law.

(Comparative Examples 1-3)
In Comparative Examples 1 to 3, the contents of urea and water were changed to those shown in Table 1 below. Other than that was carried out similarly to the said Example 1, and produced the water-based ink composition of Comparative Examples 1-3, respectively.

(Examples 4 to 13)
In Examples 4 to 13, decaglyceryl caprylate as a surface tension adjusting agent and propylene glycol as a wetting agent were further added. In addition, the preparation of the water-based ink composition of each example was made to have a composition shown in Tables 2 and 3 below. Other than that was carried out similarly to the said Example 1, and produced the water-based ink composition of Examples 4-13, respectively.

(Comparative Examples 4 to 23)
In Comparative Examples 4 to 23, the composition was as shown in Tables 4 to 7 below. Other than that was carried out similarly to the said Example 4, and produced the water-based ink composition of Comparative Examples 4-23, respectively.

(Reference Example 1)
In Reference Example 1, as shown in Table 7, food blue No. 1 was used as a dye instead of food blue No. 2. Moreover, urea as a solubilizer was not added. Otherwise, the aqueous ink composition of Reference Example 1 was produced in the same manner as in Example 13.

(Presence or absence of dye dissolution)
About all of the produced aqueous ink composition of Examples 1-13 and Comparative Examples 1-23, the presence or absence of melt | dissolution of edible blue No. 2 which is dye was confirmed. As a result, as shown in Tables 1 and 2, it was confirmed that edible blue No. 2 was completely dissolved in all the water-based ink compositions of Examples 1 to 13. On the other hand, as for the water-based ink compositions of Comparative Examples 1 to 23, as shown in Tables 3 to 7, none of food blue No. 2 could be dissolved.

  The liquid temperature of the water-based ink compositions of each example and comparative example was 21 ° C. Moreover, the presence or absence of dissolution of edible blue No. 2 in Tables 1 to 7 was evaluated as ◯ when the edible blue No. 2 was completely dissolved, and x when the edible blue No. 2 was not dissolved.

(Evaluation of ejection stability (flying performance))
As ejection stability of the water-based ink composition obtained in Example 13, evaluation of nozzle chipping, blurring of a printed image, and satellite was performed. Specifically, mat paper (trade name: Superfine paper, model number: KA4100SFR, manufactured by Epson Corporation) is prepared as a recording medium, and printing is performed using the water-based ink compositions prepared in each Example and Comparative Example. Went. Printing was performed by a single pass (one pass) method using an inkjet printer (printing jig with KC 600 dpi head).

  Nozzle chipping, blurring, and satellite are evaluated based on whether or not remarkable nozzle omission or blurring is observed in the printed image when the inkjet printer is stopped after discharging the aqueous ink composition from the head and then printed again. I did it. The results are shown in Table 8 below. In Table 8, “◯” means a case where nozzle missing, blurred or satellite was not observed, and “X” means a case where nozzle missing, blurred or satellite occurred during printing.

  The term “nozzle chipping” means that ink droplets (droplets) made of a water-based ink composition are not ejected from a nozzle where clogging has occurred. Sleeping means that the printed image is blurred and unclear in the initial stage of printing. The satellite means a dot image formed at a position different from a desired position on the recording medium due to the division of ink droplets ejected from the nozzle. Further, 15 min in Table 8 represents a time interval (open time) from when the water-based ink composition is first ejected from the head to when it is stopped and then printed again.

(Evaluation of light resistance)
The light resistance of the printed images using the aqueous ink compositions obtained in Example 13 and Reference Example 1 was evaluated. That is, tablets (placebo plain tablets not containing a drug) were prepared as recording media, and printing was performed using the aqueous ink compositions prepared in Example 13 and Reference Example 1, respectively. Printing was performed by a single pass (one pass) method using an inkjet printer (printing jig with KC 600 dpi head).

  The printed tablets were then exposed to sunlight for 4 hours under conditions of a temperature of about 15 ° C. and a relative humidity of about 30% Rh. Table 9 below shows the appearance of the printed image immediately after printing and after exposure to sunlight for 4 hours.

Subsequently, the color difference (ΔE ^* ) of the printed image exposed to sunlight for 4 hours was determined. Specifically, using an image analysis device (product name: PIAS (registered trademark) II, manufactured by Quality Engineering Associates Inc., USA), the value of L ^* a ^* b ^* color system (L ^* value). , A ^* value, b ^* value), and the light resistance was evaluated by the color difference from the blank (printed image immediately after printing). Specifically, ΔE ^* was calculated by the following formula.
ΔE ^* = {(L ^* −L ₀ ^* ) ² + (a ^* −a ₀ ^* ) ² + (b ^* −b ₀ ^* ) ² } ^1/2
L ^* , a ^* , b ^* : Coordinate values of “printed image after exposure to sunlight for 4 hours” L ₀ ^* , a ₀ ^* , b ₀ ^* : Coordinate values of “printed image immediately after printing”

(result)
Regarding the solubility of edible blue No. 2, in the aqueous ink composition according to this example, as shown in Tables 1 to 3, the edible blue No. 2 can be completely dissolved. It was confirmed that it was usable. In particular, as shown in Tables 2 and 3, the solubility of edible blue No. 2 in water improved as the urea content was increased from 10 wt% to 40 wt%.

  On the other hand, when no urea was added as in Comparative Example 1 in Table 1 and Comparative Examples 4 to 8 in Table 4, Edible Blue No. 2 could not be dissolved in the aqueous ink composition. Furthermore, as shown in Table 1, even when urea is added, the surface tension adjusting agent and the wetting agent are not added, and the urea content is less than 5 times the content of edible blue No. 2. In some cases, food blue No. 2 could not be sufficiently dissolved. In addition, as shown in Tables 5 to 6, even when the surface tension adjusting agent and the wetting agent are added, when the urea content is less than 20 times the content of Food Blue No. 2, the food blue No. 2 could not be dissolved sufficiently. In addition, even if the urea content is 20 times or more than the content of Edible Blue No. 2, if the urea content is 50 wt%, as shown in Table 7, the undissolved urea is generated. did.

  Further, with respect to ejection stability (flying performance), it was confirmed that the water-based ink composition according to Example 13 did not generate any nozzle missing, blurring, or satellite, and exhibited good ejection stability. (See Table 8).

Further, regarding the light resistance, the aqueous ink composition according to Reference Example 1 using Food Blue No. 1 had a color difference (ΔE ^* ) of 4.4 after exposure to sunlight for 4 hours, whereas Example 13 The water-based ink composition according to the present invention has a color difference (ΔE ^* ) of 1.0, which indicates that the degree of fading can be sufficiently suppressed in the case of this example.

Claims (5)

An ink-jet aqueous ink composition used for ink-jet recording,
At least water, a dye that is sparingly soluble in the water, and urea as a solubilizer that solubilizes the dye in water,
The urea content is in the range of 10% by mass to 40% by mass with respect to the total mass of the aqueous inkjet ink composition,
Furthermore, when the surface tension adjusting agent and / or wetting agent is included, the urea content is 20 times or more on the mass basis with respect to the dye content, and the surface tension adjusting agent and the wetting agent are not included. In addition, the urea content is 5 times or more on a mass basis with respect to the content of the dye.   The aqueous ink composition for inkjet according to claim 1, wherein the dye is Red No. 2 or Blue No. 2.   The water-based ink composition for inkjet according to claim 1 or 2, which has edible properties. It is a manufacturing method of the aqueous ink composition for inkjets which manufactures the aqueous ink composition for inkjets of any one of Claims 1-3,
Adding urea as the solubilizer to the water;
Returning the temperature of the water after the urea addition to room temperature;
Optionally adding a wetting agent and / or a surface tension modifier to the water;
A step of adding the dye to water containing urea whose temperature is returned to room temperature, wherein the urea content is 10% by mass to 40% by mass with respect to the total mass of the aqueous inkjet ink composition. %, And when the surface tension adjusting agent and / or wetting agent is added, the urea content is 20 times or more on a mass basis with respect to the dye content, and the surface tension adjusting agent And a step of making the urea content 5 times or more on a mass basis with respect to the dye content when no wetting agent is added. A solid preparation comprising a tablet or a capsule and having a dry film of an aqueous inkjet ink on its surface,
The solid formulation which the said water-based ink for inkjets consists of the water-based ink composition for inkjets in any one of Claims 1-3.