JP2017039788A - Aqueous ink composition for inkjet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an edible water-based ink composition for inkjet, which has excellent ejection stability and can be directly printed on tablets such as pharmaceuticals and foods by an inkjet method. An inkjet water-based ink composition according to the present invention is an inkjet water-based ink composition used for inkjet recording, and contains at least a colorant and an ejection stabilizer, and the ejection stabilizer has an HLB of 15. The following decaglyceryl laurate, which is contained in the range of 1% by mass to 5% by mass with respect to the total mass, is characterized in that the surface tension at 25 ° C. is in the range of 25 mN / m to 40 mN / m. [Selection diagram] None

Description

  The present invention relates to an aqueous inkjet ink composition, and more particularly, an edible inkjet aqueous ink composition that is excellent in dispersibility and can be directly printed on tablets such as pharmaceuticals and foods by an inkjet method. About.

  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, in the pharmaceutical industry in particular, there is an increasing need for a new printing method capable of displaying highly discriminating information even for uncoated tablets, OD tablets and the like.

  Examples of such a printing method include direct printing by an inkjet method using an aqueous inkjet ink composition (hereinafter referred to as “aqueous ink composition”). However, it is difficult to use a conventional water-based ink composition for direct printing on tablets, and it is made of a material that complies with the standards of pharmaceutical additives, Japanese Pharmacopoeia or the Food Additives Standard specified by the Pharmaceutical Affairs Law. It is necessary to use a water-based ink composition. Further, in order to directly print on a tablet by an ink jet method, it is necessary to use a water-based ink composition having excellent ejection stability.

JP 2011-236279 A

  The present invention has been made in view of the above-mentioned problems, and an object thereof is an edible ink jet that is excellent in ejection stability and can be directly printed on tablets such as pharmaceuticals and foods by an ink jet method. Another object of the present invention is to provide a water-based ink composition.

  The inventors of the present application have studied water-based ink compositions for ink jets in order to solve the above problems. 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, an aqueous inkjet ink composition according to the present invention is an inkjet aqueous ink composition used for inkjet recording in order to solve the above-described problems, and includes at least a colorant and an ejection stabilizer. The stabilizer is decaglyceryl laurate having an HLB of 15 or less, is included in the range of 1% by mass to 5% by mass with respect to the total mass, and the surface tension at 25 ° C. is in the range of 25 mN / m to 40 mN / m. It is characterized by.

  According to the said structure, when it prints by an inkjet system by containing decaglyceryl laurate whose HLB is 15 or less in the range of 1 mass%-5 mass% with respect to the total mass, from an inkjet head. The discharge stability can be improved. In addition, according to the above configuration, decaglyceryl laurate complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law, so it can be printed directly on tablets such as pharmaceuticals and foods. It is possible to do.

  Furthermore, by setting the surface tension at 25 ° C. to 25 mN / m or more, it is possible to prevent poor printing due to adhesion to the nozzle plate when ejecting droplets of the aqueous ink composition from the inkjet head. it can. In addition, it is possible to prevent the sphericity and discharge speed of the droplets of the water-based ink composition from decreasing, and to improve the droplet discharge stability. On the other hand, when the surface tension is 40 mN / m or less, it is possible to prevent the discharge stability from being lowered.

  “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 the above, and includes tablets such as pharmaceuticals and foods.

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

  In order to solve the above problems, the tablet according to the present invention is a tablet having a dry film of an aqueous inkjet ink on its surface, and the inkjet aqueous ink is composed of the inkjet aqueous ink composition. It is characterized by.

  According to the said structure, the aqueous | water-based ink composition for inkjets which contains the discharge stabilizer which consists of decaglyceryl laurate whose HLB is 15 or less as a water-based ink for inkjets in the range of 1 mass%-5 mass% with respect to the total mass. Therefore, even if printing is directly performed on the tablet surface by the ink jet recording method with the water-based ink for ink jet, a dry film capable of forming a good printed image without forming a defective discharge or blurring of the image can be formed. Thereby, it is possible to display product information on the tablet body, and it is possible to provide a tablet capable of improving identification and preventing dispensing mistakes and accidental ingestion.

  According to the present invention, decaglyceryl laurate having an HLB of 15 or less is contained in the range of 1% by mass to 5% by mass with respect to the total mass, and the surface tension is in the range of 25 mN / m to 40 mN / m. By doing so, it is possible to provide a water-based ink composition for inkjet excellent in ejection stability. In addition, decaglyceryl laurate complies with the standards of pharmaceutical additives, Japanese pharmacopoeia or food additives official regulations stipulated by the Pharmaceutical Affairs Law, so it can be printed directly on tablets such as pharmaceuticals and foods. is there. As a result, it is possible to display product information on the tablet body, improve identification, and prevent dispensing errors and accidental ingestion.

  That is, according to the present invention, an edible ink-jet aqueous ink composition that is excellent in ejection stability and can be directly printed on tablets such as pharmaceuticals and foods by an ink-jet method, and the ink-jet water-based ink Tablets printed with the composition can be provided.

(Water-based ink composition for inkjet)
The water-based ink composition for inkjet according to the present embodiment (hereinafter referred to as “water-based ink composition”) will be described below using a pigment as an example of a colorant.

  The water-based ink composition according to the present embodiment is a water-based ink containing at least a pigment composition and decaglyceryl laurate as an ejection stabilizer and having a main solvent of water. In addition, the water-based ink composition of the present embodiment can be made edible by using a material that complies with standards such as the Pharmaceutical Affairs Law, and is suitably used for inkjet recording. is there. Furthermore, since a water-based ink composition uses a pigment as a coloring material, it is superior in terms of color developability, light resistance, water resistance and the like as compared with an ink composition using a dye.

  The pigment composition is a composition containing at least a pigment and at least a pigment dispersant.

  As said pigment, what is normally used for the water-based ink composition for inkjets, such as carbon black, can be used, for example. Examples of the carbon black include channel black, furnace black, acetylene black, and thermal black. Moreover, it is also possible to use a commercial item as carbon black of this Embodiment, As such a commercial item, # 900, # 970, # 100, # 2200, # 2300, # 2350, # 2600, MA-7, MA-8, MA-100, MA-11, MCF88, # 45L, # 50, # 10, # 33, # 40, # 4000, # 52, CF9, etc. (trade names, all Mitsubishi Chemical Co., Ltd.), Niteron, HTC (trade names, all manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.), Asahi # 55, Asahi # 51, Asahi # 50U, Asahi # 50, Asahi # 35, Asahi # 15, Asahi Thermal (product) Name, all manufactured by Asahi Carbon Co., Ltd.), Raven700, 5750, 5250, 5000, 3500, 1255 (trade names, all manufactured by Columbia), REGAL400R, 330R, 660R, ogulL, Monarch 700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (product names, all manufactured by Cabot), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170 (product names, any Also manufactured by Degussa), PRINTEX35, U, V, 140U, 140V (trade names, all manufactured by Degussa), Special Black 6, 5, 4A, 4 (trade names, all manufactured by Degussa), TOKABLACK # 8500, # 8300, # 7550, # 7400, # 7350, # 7240, # 7100, # 7050, # 5500, # 4500, # 4400, # 4300 (trade names, all manufactured by Tokai Carbon Co., Ltd.) and the like. These pigments can be used alone or in admixture of two or more as required. However, when the pigment composition of the present embodiment is used for printing on the tablet surface of pharmaceuticals, foods, etc., carbon black conforms to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. It is preferable to use a suitable one.

  The average primary particle diameter of the carbon black is preferably 10 nm to 40 nm. The average primary particle diameter is an arithmetic average particle diameter obtained by observing the carbon black particles before being dispersed in a solvent together with a dispersing agent by SEM (scanning electron microscope) or TEM (transmission electron microscope). Means.

  As the pigment, for example, iron oxide can be used. Examples of the iron oxide include yellow iron oxide, yellow ferric oxide, ferric oxide, red iron oxide, black iron oxide, and the like. These pigments can be used alone or in admixture of two or more as required. However, when the pigment composition of the present embodiment is used for printing on the surface of tablets such as pharmaceuticals and supplements, iron oxide conforms to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. It is preferable that they are compatible.

  The content of the pigment directly affects the image density. When printing on a water-based ink composition, such as storage stability, viscosity, pH, and tablets, the printing density is affected. It is sufficient to set appropriately considering this point. For example, in the case of carbon black, normally, the range of 0.5% to 40% by mass is preferable with respect to the total mass of the pigment composition, and the range of 1% to 25% by mass is more preferable. By setting the carbon black content to 0.5% by mass or more, a decrease in image density can be suppressed. On the other hand, by setting the carbon black content to 40% by mass or less, it is possible to prevent a decrease in gloss, nozzle clogging, and a decrease in ejection stability. Moreover, when a pigment is iron oxide, the range of 0.5 mass%-40 mass% is preferable normally with respect to the total mass of a pigment composition, and the inside of the range of 1 mass%-25 mass% is more preferable. By making the content of iron oxide 0.5% by mass or more, a decrease in image density can be suppressed. On the other hand, by setting the content of iron oxide to 40% by mass or less, it is possible to prevent a decrease in gloss, nozzle clogging, and a decrease in ejection stability.

  For example, when the pigment is carbon black, the average dispersed particle diameter D50 of the pigment in the dispersed state is preferably in the range of 50 nm to 200 nm, and more preferably in the range of 85 nm to 140 nm. When the pigment is iron oxide, the D50 is preferably in the range of 25 nm to 300 nm, more preferably in the range of 100 nm to 300 nm, still more preferably in the range of 75 nm to 250 nm, and in the range of 75 nm to 210 nm. Particularly preferred. By setting the D50 to be equal to or more than the lower limit values of carbon black and iron oxide, it is possible to prevent the dispersion stability, light resistance and ejection stability from deteriorating and to prevent the printing density from being lowered. On the other hand, by making D50 below the upper limit value of each of carbon black and iron oxide, separation and sedimentation of the pigment can be prevented and dispersion stability can be maintained. The 99% cumulative value (D99) of the particle size distribution of the carbon black is preferably in the range of 100 nm to 500 nm. Further, D99 of the iron oxide is preferably in the range of 100 nm to 900 nm, more preferably in the range of 100 nm to 600 nm, and particularly preferably in the range of 100 nm to 500 nm. The average dispersed particle diameters D50 and D99 of the pigment are values measured by a dynamic light scattering method using Microtrac UPA-EX150 (trade name, manufactured by Nikkiso Co., Ltd.).

  As the pigment dispersant, those usually used in an aqueous inkjet ink composition can be used. Specific examples include nonionic surfactants and anionic surfactants. Examples of the nonionic surfactant include polyoxyethylene hydrogenated castor oil, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, and polyoxyethylene behenyl ether. Examples thereof include oxyethylene alkyl ether, polysorbate, and decaglyceryl oleate. Examples of the anionic surfactant include sodium polyacrylate. These may be used alone or in admixture of two or more. However, when the pigment composition of this embodiment is used for printing on the surface of tablets such as pharmaceuticals and foods, it must conform to the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. It is preferable to use it.

  In addition, as the pigment dispersant, the polyoxyethylene hydrogenated castor oil is suitable for improving the dispersibility of a pigment made of carbon black. Polyoxyethylene hydrogenated castor oil conforms to the standards for pharmaceutical additives and the like under the Pharmaceutical Affairs Law. Therefore, polyoxyethylene hydrogenated castor oil can be suitably used for printing on tablets or the like of pharmaceuticals or foods. The polyoxyethylene hydrogenated castor oil is not particularly limited. For example, polyoxyethylene hydrogenated castor oil (20E.O.) (polyoxyethylene glycerin trioxystearic acid 20), polyoxyethylene hydrogenated castor oil (40E.O. ) (Polyoxyethylene glycerol trioxystearic acid 40), polyoxyethylene hydrogenated castor oil (50 EO) (polyoxyethylene glycerin trioxystearic acid 50), polyoxyethylene hydrogenated castor oil (60 EO) ( And polyoxyethylene glycerin trioxystearic acid 60), polyoxyethylene hydrogenated castor oil (100E.O.) (polyoxyethylene glycerin trioxystearic acid 100), and the like. You may use these individually by 1 type or in mixture of 2 or more types. E.E. O. Represents the average number of moles of oxyethylene added.

  Examples of the polyoxyethylene hydrogenated castor oil (20E.O.) include Nikkor HCO-20 (trade name, manufactured by Nikko Chemicals Co., Ltd.), Emarex HC-20 (trade name, manufactured by Nippon Emulsion Co., Ltd.). And UNIOX HC-20 (trade name, manufactured by NOF Corporation).

  Examples of the polyoxyethylene hydrogenated castor oil (40E.O.) include, for example, Nikkor HCO-40 (trade name, manufactured by Nikko Chemicals Co., Ltd.), UNIOX HC-40 (manufactured by NOF Corporation), Emanon CH40. (Manufactured by Kao Corporation), Cremophor (trade name, manufactured by BASF Japan Co., Ltd.), oil mugine HRE40 (trade name, manufactured by Henkel Japan Co., Ltd.), Emarex HC-40 (trade name, Nippon Emulsion Co., Ltd.) Manufactured) and the like.

  Examples of the polyoxyethylene hydrogenated castor oil (50E.O.) include, for example, Nikkor HCO-50 (trade name, manufactured by Nikko Chemicals Co., Ltd.), UNIOX HC-50 (trade name, manufactured by NOF Corporation). And Emalex HC-50 (trade name, manufactured by Nippon Emulsion Co., Ltd.).

  Examples of the polyoxyethylene hydrogenated castor oil (60EO) include, for example, Nikkor HCO-60 (trade name, manufactured by Nikko Chemicals Co., Ltd.), UNIOX HC-60 (trade name, manufactured by NOF Corporation). , Emanon CH-60 (trade name, manufactured by Kao Corporation), Cremophor (trade name, manufactured by BASF Japan Ltd.), Oil Mugin HRE60 (trade name, manufactured by Henkel Japan Corporation), Emalex HC-60 ( Trade name, manufactured by Nippon Emulsion Co., Ltd.).

  Examples of the polyoxyethylene hydrogenated castor oil (100E.O.) include, for example, Nikkor HCO-100 (trade name, manufactured by Nikko Chemicals Co., Ltd.), UNIOX HC-100 (trade name, manufactured by NOF Corporation). And Emalex HC-100 (trade name, manufactured by Nippon Emulsion Co., Ltd.).

The HLB (hydrophilic lipophilic ratio) of the polyoxyethylene hydrogenated castor oil is preferably 10 or more, more preferably 10-18. When the HLB is 10 or more, the affinity of the polyoxyethylene hydrogenated castor oil for the dispersion medium is improved, and the dispersion stability is improved. The upper limit value of the HLB is not particularly limited, but if it is greater than 18, the affinity with the dispersion medium is too good, and the polyoxyethylene hydrogenated castor oil is easily detached from the pigment surface, resulting in a decrease in dispersion stability. There is a case. 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 ratio of the pigment to the pigment dispersant is preferably 1: 0.2 to 1: 4, more preferably 1: 0.5 to 1: 1 on a mass basis. When the content ratio is 1: 0.2 or more, it is possible to prevent a decrease in dispersibility of the pigment. On the other hand, when the content ratio is 1: 4 or less, for example, when used in an aqueous inkjet ink composition, it is possible to prevent a decrease in ejection stability due to adhesion of a nozzle plate.

  In the pigment composition, a dispersion medium for dispersing the pigment is included. Examples of the dispersion medium include water, and more specifically, pure water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, and distilled water, or those obtained by removing ionic impurities such as ultrapure water. . In particular, water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is preferable because generation of mold and bacteria can be prevented over a long period of time. Moreover, it is not specifically limited as content of a dispersion medium, It can set as needed suitably.

  Further, as the dispersion medium, a mixed solution of the water and the water-soluble organic solvent may be used. The water-soluble organic solvent is not particularly limited, and specifically, for example, alcohols such as methyl alcohol, ethyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, n-propyl alcohol, isopropyl alcohol; Amides such as dimethylformamide and dimethylacetamide; Ketones such as acetone and methyl ethyl ketone; Tetrahydrofuran, dioxane, ethylene glycol methyl ether, ethylene glycol ethyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, triethylene glycol monomethyl ether, triethylene glycol mono Ethers such as ethyl ether; ethylene glycol, propylene glycol, butylene glycol , Diethylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerin, polyglycerin and other polyhydric alcohols; N-methylpyrrolidone, 1,3 -Dimethyl-2-imidazolidinone and the like. You may use these individually by 1 type or in mixture of 2 or more types. Among these water-soluble organic solvents, ethyl alcohol, n-butyl alcohol, isobutyl alcohol, n-propyl are those that fall under the standards of pharmaceutical additives, Japanese pharmacopoeia or official food additives specified by the Pharmaceutical Affairs Law. Alcohol, isopropyl alcohol, acetone, propylene glycol, polyethylene glycol and glycerin are preferred. Furthermore, the blending amount when a water-soluble organic solvent is used as the dispersion medium is not particularly limited, and can be appropriately set as necessary.

  The content of the pigment composition is preferably in the range of 0.5% by mass to 20% by mass and more preferably in the range of 1% by mass to 15% by mass with respect to the total mass of the water-based ink composition. By making the content of the pigment composition 0.5% by mass or more, the coloring power can be improved. On the other hand, dispersibility can be improved by making the content of the pigment composition 20% by mass or less.

  In the method for producing the pigment composition, the mixing method and the order of addition of the pigment, the pigment dispersant, the dispersion medium, and other additives blended as necessary are not particularly limited. For example, a pigment, a pigment dispersant, water as a dispersion medium, and the like may be mixed at a time, and the mixture may be subjected to a dispersion treatment using a normal disperser. The dispersion time at this time is not particularly limited, but is preferably set so that the average dispersed particle diameter of the pigment is within the above numerical range.

  The disperser used in the pigment dispersion treatment is not particularly limited as long as it is a commonly used disperser. Specific examples include a ball mill, a roll mill, a sand mill, a bead mill, a paint shaker, and a nanomizer.

  Since decaglyceryl laurate as the discharge stabilizer complies with the standards for pharmaceutical additives and the like stipulated by the Pharmaceutical Affairs Law, it enables direct printing on tablets and the like of pharmaceuticals and foods.

  The decaglyceryl laurate has an HLB (hydrophilic / lipophilic ratio) of 15 or less, preferably in the range of 14-15. By containing the decaglyceryl laurate, the ejection stability from the inkjet head can be improved when printing is performed by the inkjet method. The lower limit of the HLB is not particularly limited, but when it is 10 or more, the HLB can be stably dissolved in an aqueous solvent. Further, the HLB value is an HLB value obtained by the Griffin method, as described above.

  Content of the said decaglyceryl laurate is 1 mass%-5 mass% with respect to the total mass of an aqueous ink composition, and the range of 1 mass%-3 mass% is preferable. By making the content of decaglyceryl laurate 1% by mass or more, it is possible to prevent the discharge stability from being lowered. On the other hand, if the content of decaglyceryl laurate is more than 5% by mass, bubbles are likely to be generated, which may cause nozzle clogging.

  The surface tension of the water-based ink composition of the present embodiment is in the range of 25 mN / m to 40 mN / m at 25 ° C., and preferably in the range of 27 mN / m to 36 mN / m. By setting the surface tension to 25 mN / m or more, it is possible to prevent printing defects due to adhesion to the nozzle plate when discharging droplets of the aqueous ink composition from the inkjet head. In addition, it is possible to prevent the sphericity and discharge speed of the droplets of the water-based ink composition from decreasing, and to improve the droplet discharge stability. On the other hand, when the surface tension is 40 mN / m or less, it is possible to prevent the discharge stability from being lowered.

  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 addition of hydrogen peroxide 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.

  In the aqueous ink composition of the present embodiment, other additives may be blended. However, when used as an ink-jet ink for tablets 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 water-soluble resins, organic amines, surfactants, pH adjusters, chelating agents, preservatives, viscosity adjusters, and antifoaming agents. The content of these additives is not particularly limited, and can be appropriately set as necessary.

  The surface tension adjusting agent is not particularly limited as long as it is compatible with the standards of the Pharmaceutical Affairs Law and can adjust the surface tension of the aqueous ink composition. Specifically, for example, caprylic acid decaglycerin ester, oleic acid decaglycerin ester, myristic acid decaglycerin ester, stearic acid decaglycerin ester, lauric acid hexaglycerin ester, oleic acid hexaglycerin ester, myristic acid hexaglycerin ester, condensation Linolenic acid tetraglycerin ester, fatty acid ester palm palm, glycerin fatty acid ester mixture, stearic acid glycerin ester (self-emulsifying type), pyroglutamic acid POE, monolauric acid polyethylene glycol (10EO), monooleic acid polyethylene glycol (6EO), polyoxyethylene Palm oil fatty acid sorbitan (20EO), polyoxyethylene sorbitan monostearate (20EO), poly monooleate Carboxymethyl sorbitan (20 EO), monopalmitate polyoxyethylene sorbitan (20EO), POE (4.2) lauryl ether, POE (9) lauryl ether and the like. You may use these individually by 1 type or in mixture of 2 or more types.

  Among these surface tension modifiers, caprylic acid decaglycerin ester (trade name; Ryoto polyglycerin CE19D, manufactured by Mitsubishi Chemical Foods), caprylic acid decaglycerin ester ( Product name: SY glyceric MCA750, Sakamoto Yakuhin Kogyo), oleic acid decaglycerin ester (trade name; NIKKOL DECAGLLYN 1-OV, manufactured by Nikko Chemicals), oleic acid decaglycerin ester (trade name: SY glycerase MO-7S, Sakamoto Yakuhin Kogyo Co., Ltd.), lauric acid hexaglycerin ester (trade name; NIKKOL HEXAGLYN 1-L, manufactured by Nikko Chemicals Co., Ltd.), lauric acid hexaglycerin ester (brand name: SY Glister ML-500, Sakamoto Pharmaceutical Co., Ltd.) (Made by) Acid hexaglycerin ester (trade name: SY Glyster MO-5S, manufactured by Sakamoto Pharmaceutical Co., Ltd.), condensed linolenic acid tetraglycerin ester (trade name: SY Glyster CR-310, manufactured by Sakamoto Pharmaceutical Co., Ltd.), fatty acid It is preferable to use a commercially available product such as ester palm palm (trade name; Tirabazole W-01, manufactured by Taiyo Kagaku Co., Ltd.).

  The addition amount of the surface tension adjusting agent is preferably within a range in which the surface tension of the aqueous ink composition can be adjusted to 25 to 40 mN / m. When the addition amount is within the above range, it is possible to ensure ejection stability at the time of printing by the ink jet method.

  The wetting agent is not particularly limited as long as it conforms to standards such as the Pharmaceutical Affairs Law, and specific examples include propylene glycol, glycerin, dipropylene glycol and the like.

  The addition amount of the wetting agent is preferably 3% by mass to 50% by mass and more preferably 10% by mass to 40% by mass with respect 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 nozzle of the inkjet head can be prevented, and the ejection performance can be further improved. On the other hand, by setting the content of the wetting agent to 50% by mass or less, the viscosity of the aqueous ink composition can be appropriately controlled.

  The water-based ink composition of the present embodiment can be produced by mixing the aforementioned components by an appropriate method. That is, for example, the decaglyceryl laurate and other additives are added to the dispersion of the pigment composition and further diluted with water. Thereafter, the mixture is sufficiently stirred, and if necessary, filtration is performed to remove coarse particles and foreign matters that cause clogging. Thereby, the water-based ink composition which concerns on this Embodiment can be obtained.

  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 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. Moreover, since the water-based ink composition of this Embodiment is excellent in discharge stability, it can be used conveniently for an inkjet ink. Furthermore, since the water-based ink composition of the present embodiment uses a material that complies with the standards of pharmaceutical additives, Japanese Pharmacopoeia or the Food Additives specified by the Pharmaceutical Affairs Law, it has edible properties. It can be printed directly on the surface of tablets 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. Furthermore, since the water-based ink composition using a pigment is excellent in light resistance, the occurrence of bleeding can be prevented even when directly printed on the surface of a tablet such as a pharmaceutical or a supplement.

(tablet)
The tablet according to the present embodiment is printed directly on the surface of the tablet by the inkjet recording method using the inkjet aqueous ink composed of the aqueous ink composition. Have As described above, since the water-based ink composition is excellent in ejection stability and does not generate fading in the printed image, the tablet can be printed with various information such as product information for improving user identification, As a result, 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 shape of the tablet is not particularly limited, and any shape can be adopted. The tablet may be a pharmaceutical use tablet or a food use tablet. 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 tablet 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 adhered to the tablet surface. The discharge method is not particularly limited, and for example, a known method such as continuous injection type (charge control type, spray type, etc.), on-demand type (piezo type, thermal type, electrostatic suction type, etc.) can be adopted. it can.

(Other matters)
In the present embodiment, the case where a pigment is used as a colorant has been described as an example. However, the present invention is not limited to this, and for example, a dye can be used. In this case, other known additives may be added as necessary.

  The dye is not particularly limited as long as it is edible, and for example, it can be appropriately selected from conventionally known synthetic edible pigments, natural pigment derivatives, natural synthetic pigments, natural edible pigments and the like. There is no particular limitation on the synthetic food color, for example, Food Red No. 2, Food Red No. 3, Food Red No. 40, Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Red No. 4 No., Edible Yellow No. 5, Edible Blue No. 1, Edible Blue No. 2, Edible Green No. 3, and the like. It does not specifically limit as a natural pigment derivative, For example, copper chlorophyllin sodium etc. are mentioned. It does not specifically limit as a natural synthetic pigment, For example, (beta) -carotene etc. are mentioned. The natural food coloring is not particularly limited, and examples thereof include anthocyanin dyes, carotenoid dyes, quinone dyes, and flavonoid dyes. You may use these individually by 1 type or in mixture of 2 or more types.

  Although content of dye is not specifically limited, Usually, it exists in the range of 0.2 mass%-20 mass% with respect to the total mass of an aqueous ink composition, Preferably it is 1 mass%-10 mass%.

  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 and 2)
The pigment dispersion solutions of Examples 1 and 2 were prepared with the composition shown in Table 1 below. Specifically, each material shown in Table 1 and zirconia beads were placed in a container and mixed, and dispersed at room temperature for 16 hours (dispersion time) with a dispersing machine (Paint Shaker, manufactured by Asada Tekko Co., Ltd.). For each of Examples 1 and 2, pigment dispersion solutions having a carbon black pigment concentration of 25% by mass were obtained.

  Further, aqueous ink compositions of Examples 1 and 2 were prepared with the blending compositions shown in Tables 2 and 3 below. Specifically, propylene glycol, water, and decaglyceryl laurate (prepared to a concentration of 10% by mass) were added to a pigment dispersion solution composed of the pigment composition to prepare aqueous ink compositions, respectively.

  The numerical values in Table 1 below are mass% values relative to the total mass of the pigment dispersion solution, and the numerical values in Tables 2 and 3 are mass% values relative to the total mass of the aqueous ink composition. 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 discharge stabilizer was changed to that shown in Table 3 as decaglyceryl laurate. Other than that was carried out similarly to the said Example 1, and created the water-based ink composition of Comparative Examples 1-3, respectively.

(Evaluation of missing nozzles and fading)
As ejection stability of the water-based ink compositions of each Example and Comparative Example, evaluation of nozzle omission and blurring of a printed image was performed. That is, mat paper (trade name: Superfine paper, manufactured by Epson Corporation) was prepared as a recording medium, and printing was performed using the water-based ink compositions prepared in Examples and Comparative Examples. Printing was performed by a single pass (one pass) method using an inkjet printer (printing jig with KC 600 dpi head).

  Evaluation of nozzle omission and fading was performed by checking whether nozzle omission or fading was observed in the printed image when the ink jet printer was stopped after discharging the aqueous ink composition from the head and then printing was performed again. . The results are shown in Table 3 above. A circle in the table means a case where neither nozzle missing nor fading was observed. X means a case where at least one of nozzle missing or blurring occurs during printing.

  The term “nozzle missing” means that ink droplets (droplets) made of a water-based ink composition are not ejected from a nozzle where clogging has occurred. Fading means fading of an image at the initial stage of printing. Further, 15 min in Table 3 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.

(Measurement of surface tension of water-based ink composition)
The surface tension of the water-based ink compositions of each Example and Comparative Example was measured at room temperature (25 ° C.) using a surface tension meter (trade name: DY-500, manufactured by Kyowa Interface Science Co., Ltd.). The results are shown in Table 3 above.

(result)
As can be seen from the experimental results of Examples 1 and 2 shown in Table 3, when decaglyceryl laurate having an HLB of 15 or less was blended to 2% by mass with respect to the total mass of the aqueous ink composition, nozzle omission and No fading occurred, and it was confirmed that good ejection stability was exhibited.

On the other hand, in Comparative Examples 1 to 3, it was confirmed that the same decaglyceryl laurate having nozzles with HLB greater than 15 caused nozzle omission and blurring. In particular, although the surface tension was the same value between the water-based ink composition of each comparative example and the water-based ink composition of each example, there was a difference in ejection stability.

Claims (3)

An ink-jet aqueous ink composition used for ink-jet recording,
At least a colorant and a discharge stabilizer,
The ejection stabilizer is decaglyceryl laurate having an HLB of 15 or less, and is contained in a range of 1% by mass to 5% by mass with respect to the total mass,
An aqueous inkjet ink composition having a surface tension at 25 ° C. in the range of 25 mN / m to 40 mN / m.   The water-based ink composition for inkjet according to claim 1, which is edible. A tablet having a dry film of a water-based ink for inkjet on the surface,
The tablet which the said water-based ink for inkjets consists of the water-based ink composition for inkjets of Claim 1 or 2.