Inkjet ink and tablet printed matter

Abstract

The purpose of the present invention is to provide an inkjet ink having drying properties, light resistance, and discharge stability, and a tablet printed matter having a printed section printed by the inkjet ink. The ink according to the present embodiment contains Red 102, reduced isomaltulose, water as a solvent, a monohydric alcohol, and a wetting agent, the monohydric alcohol contains at least one of ethanol, NPA, and IPA, the wetting agent contains at least one of glycerin and PG, the blending ratio of Red 102 is in the range of 0.5-3.0 mass% with respect to the mass of the entire inkjet ink, and the blending ratio of Red 102 is in the range of 0.5-3.0 mass% with respect to the mass of the entire inkjet ink. The blending ratio of the monohydric alcohol is in the range of 30 mass% to 60 mass% with respect to the mass of the entire inkjet ink, and the blending ratio of the wetting agent is in the range of 0.05 mass% to 10 mass% with respect to the mass of the entire inkjet ink.

Description

Technical Field

[0001] The present invention relates to inkjet inks and tablet printing. Background Art

[0002] Inkjet printing ink (hereinafter, also simply referred to as "inkjet ink" or "ink") may be made edible by using, for example, an edible dye such as a tar-based coloring matter as a coloring material.

[0003] Conventionally, in inkjet inks, due to the degradation of color materials, discoloration in which the color (hue) of the color material changes, fading due to the reduction of the chroma of the color material, etc. may occur in the printed characters and images. For example, when the light resistance of the inkjet ink is insufficient, the color material decomposes (photodecomposition) due to the action of light, and discoloration and fading (photochromic fading) may occur. Such discoloration and fading are recognized as reduced visibility of the printed characters and images (hereinafter collectively referred to as "printed images").

[0004] In order to suppress such discoloration and fading of printed images, technical development is being carried out, and various methods for suppressing discoloration and fading have been proposed (for example, Patent Document 1).

[0005] In addition, when printing characters and images on tablets, inkjet inks containing food dyes with color development are sometimes used to improve visibility. In addition, the food dyes contained in the inks have a problem of large discoloration / fading caused by light.

[0006] In recent years, there has been an increasing demand for inkjet inks with excellent drying properties. Therefore, in order to improve the drying properties of inkjet inks, when the content of drying solvents such as alcohol (lower alcohol) contained in the inkjet ink is increased, the nozzles provided by the inkjet printer are accelerated to dry at the nozzle liquid surface, and the ejection properties of the inkjet ink are deteriorated, or the color material is precipitated. In particular, inkjet inks containing Edible Red No. 102 tend to have an easy deterioration in the ejection properties of the inkjet ink.

[0007] Furthermore, conventionally, when printing characters and images on tablets, viscosity modifiers are sometimes added to inkjet inks to adjust the viscosity of the inkjet inks in order to obtain good printing characteristics such as high ink droplet landing accuracy.

[0008] As a viscosity modifier for adjusting the viscosity of inkjet ink or the like, for example, a non-volatile liquid such as glycerin, or a thickener such as sodium alginate or hydroxypropylmethylcellulose can be used.

[0009] However, when a nonvolatile liquid such as glycerin is used as the viscosity modifier, the drying properties of the inkjet ink or the like may be reduced.

[0010] In addition, when a thickener such as sodium alginate or hydroxypropyl methylcellulose is used as the viscosity modifier, when the solvent contained in the inkjet ink is a quick-drying solvent (a solvent containing a lower alcohol and water), the solubility of the thickener in the quick-drying solvent decreases, and the ejection stability of the ink is reduced. In addition, when a thickener such as sodium alginate or hydroxypropyl methylcellulose is used as the viscosity modifier, the drying of the nozzle liquid surface is accelerated, and the ejection stability of the ink is sometimes reduced.

[0011] As described above, in conventional inkjet inks and the like, drying properties, light resistance, and discharge stability are often in a trade-off relationship.

[0012] Prior art literature

[0013] Patent Literature

[0014] Patent Document 1: Japanese Patent No. 6389506 Summary of the invention

[0015] Problems to be solved by the invention

[0016] The present invention has been made in view of the above problems, and an object of the present invention is to provide an ink (inkjet ink) having drying properties, light resistance, and ejection stability, and a tablet (tablet printed product) having a printed portion printed with the ink (inkjet ink).

[0017] Means for solving problems

[0018] In order to achieve the above-mentioned object, an ink (inkjet ink) involved in one embodiment of the present invention contains Red No. 102, reduced isomaltulose, water as a solvent, a monohydric alcohol, and a wetting agent, wherein the monohydric alcohol contains at least one of ethanol, NPA and IPA, and the wetting agent contains at least one of glycerol and PG, the mixing ratio of Red No. 102 is in the range of 0.5 mass% to 3.0 mass% relative to the mass of the entire inkjet ink, the mixing ratio of the monohydric alcohol is in the range of 30 mass% to 60 mass% relative to the mass of the entire inkjet ink, and the mixing ratio of the wetting agent is in the range of 0.05 mass% to 10 mass% relative to the mass of the entire inkjet ink.

[0019] In order to achieve the above object, a tablet (printed tablet) according to one embodiment of the present invention is characterized by comprising a printed portion printed with the above ink (inkjet ink).

[0020] Effects of the Invention

[0021] According to one embodiment of the present invention, it is possible to provide an inkjet ink having good drying properties, light resistance, and discharge stability, and a tablet printed article having a printed portion obtained by printing with the inkjet ink. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] [ Figure 1 ] is a schematic diagram illustrating the permeability and light resistance of the inkjet ink according to an embodiment of the present invention.

[0023] [ Figure 2 ] is a schematic cross-sectional view showing an example of a tablet (plain tablet) involved in an embodiment of the present invention.

[0024] [ Figure 3 ] is a schematic cross-sectional view showing an example of a tablet (film-coated tablet) according to an embodiment of the present invention.

[0025] [ Figure 4 ] is an example of a printed image of a tablet (plain tablet) involved in an embodiment of the present invention.

[0026] [ Figure 5 ] is an example of a printed image of a tablet (film-coated tablet) involved in an embodiment of the present invention.

[0027] Explanation of symbols

[0028] 1 Tablet base material

[0029] 1S Surface

[0030] 3 Printing images

[0031] 4 Specific dyes

[0032] 5 plain prints

[0033] 7 Film coating layer

[0034] 9 Film-coated tablets printed material

[0035] 11 Blank printed image (solid image)

[0036] 13. Printed image of film-coated tablets (two-dimensional barcode) DETAILED DESCRIPTION

[0037] The inkjet ink (ink) according to an embodiment of the present invention (hereinafter referred to as "the present embodiment") is an inkjet ink containing a viscosity modifier, and for example, it is an inkjet ink that can sufficiently suppress the photochromic fading of a printed image or the like on the surface of a medical tablet by an inkjet printing method, maintain light resistance, and has excellent ejection stability (intermittent recovery) and excellent drying properties, and a tablet printed product having a printed portion printed using the inkjet ink. The configuration of the inkjet ink according to the embodiment of the present invention and the tablet printed product having a printed portion printed using the inkjet ink will be described in detail below.

[0038] 〔Inkjet ink composition〕

[0039] The inkjet ink according to the present embodiment is an edible inkjet ink, which contains Edible Red No. 102 (hereinafter referred to as "Red No. 102") as an edible dye (food coloring), reduced isomaltulose, water as a solvent, a monohydric alcohol, and a wetting agent, wherein the monohydric alcohol contains at least one of ethanol, NPA, and IPA, and the wetting agent contains at least one of glycerol and PG, the mixing ratio of Red No. 102 is in the range of 0.5 mass % to 3.0 mass % relative to the mass of the entire inkjet ink, the mixing ratio of the monohydric alcohol is in the range of 30 mass % to 60 mass % relative to the mass of the entire inkjet ink, and the mixing ratio of the wetting agent is in the range of 0.05 mass % to 10 mass % relative to the mass of the entire inkjet ink.

[0040] Within the following range.

[0041] The reduced isomaltulose used in the present embodiment functions as a viscosity modifier for adjusting the viscosity of inkjet ink. In addition, the reduced isomaltulose also has a fixation property (ink fixation property) for fixing the ink to the surface of a printed object (eg, a solid preparation).

[0042] According to the above configuration, it is possible to sufficiently suppress the photochromic fading of the printed image, maintain the light resistance of the inkjet ink, and have excellent ejection stability and excellent drying properties. Figure 1 The mechanism related to the improvement of light resistance is described. Then, the mechanism related to the improvement of discharge stability is described.

[0043] Figure 1 This is a schematic diagram for explaining the relationship between the fixation of ink on the surface of a printed object (solid preparation) and light resistance. Here, as a solid preparation, for example, a tablet with few voids and a film coating portion, i.e., a film-coated (FC) tablet is used. It should be noted that the present invention is not limited to this, and a plain tablet or a capsule tablet can also be used as a printed object.

[0044] Figure 1(a) to Figure 1 (c) is a schematic cross-sectional view of a tablet (film-coated tablet in this case) after a certain period of time has passed after printing inkjet inks A to C of different compositions on the tablet. In this example, inkjet ink A is an ink containing a mixture of water as a solvent, at least one of ethanol, n-propanol (NPA) and isopropanol (IPA), i.e., a monohydric alcohol, and at least one of glycerol and propylene glycol (PG), i.e., a wetting agent, using specific dye 4 as a colorant. Specific dye 4 can be exemplified by Red No. 102.

[0045] Inkjet ink B is an ink obtained by adding a predetermined viscosity modifier to inkjet ink A. Here, the viscosity modifier added to inkjet ink B is a viscosity modifier (e.g., maltose) that has a relatively high solubility in water and a relatively low ink fixation. Inkjet ink C is an ink obtained by adding reduced isomaltulose as a viscosity modifier having a relatively high ink fixation to inkjet ink A.

[0046] Specifically, Figure 1 (a) is a schematic cross-sectional view of a tablet in the thickness direction after a certain period of time (e.g., 140 hours) has passed after an inkjet ink A is printed on the surface 1S of a tablet substrate 1. The inkjet ink A contains a specific dye 4 as a colorant, and contains a mixture of water as a solvent; at least one of ethanol, n-propanol (NPA) and isopropanol (IPA), i.e., a monohydric alcohol; and at least one of glycerol and propylene glycol (PG), i.e., a wetting agent. In addition, Figure 1 (b) is a schematic cross-sectional view in the thickness direction of the tablet after the inkjet ink B is printed on the surface 1S of the tablet substrate 1 for a certain period of time (e.g., 140 hours). Figure 1 (c) is a schematic cross-sectional view in the thickness direction of a tablet after the inkjet ink C is printed on the surface 1S of the tablet substrate 1 and a certain period of time (eg, 140 hours) has passed.

[0047] First, the permeability of inkjet inks A and B depending on whether or not a viscosity modifier or a dye is added to the inkjet ink will be described as an example.

[0048] Among various color materials used in inkjet inks, for example, tar-based pigments used as food dyes may cause discoloration and fading in characters and images printed on the surface of solid preparations. For example, Red No. 102 among tar-based pigments may permeate into solid preparations over time, or discolor and fade the printed image due to photodecomposition. In contrast, by adding a viscosity modifier to the inkjet ink, it is possible to suppress the penetration of the dye into the solid preparation, thereby suppressing the discoloration and fading of the printed image.

[0049] like Figure 1As shown in (a), when the inkjet ink A containing no viscosity modifier is printed, the specific dye 4 penetrates into the inside of the tablet substrate 1 after a certain time has passed since the start of printing. Here, the penetration depth of the specific dye 4 in the inkjet ink A after the certain time has passed is referred to as the penetration depth X (μm). Figure 1 As shown in (b), when printing inkjet ink B containing a viscosity modifier (e.g., maltose) having relatively low ink fixation, after a certain period of time from the start of printing, the penetration depth Y (μm) of inkjet ink B is smaller than the penetration depth X of inkjet ink A (X>Y).

[0050] In the inkjet ink B, due to the increase in ink viscosity caused by the addition of a predetermined viscosity modifier, the penetration of the specific dye 4 into the substrate 1 of the tablet is suppressed. Therefore, in the case of printing the inkjet ink B, even after a certain period of time has passed since the start of printing, the specific dye 4 remains near the surface 1S in the substrate 1 of the tablet. That is, compared with the case where the viscosity modifier is not added, the inkjet ink containing the predetermined viscosity modifier can suppress the discoloration and fading of the printed image caused by the penetration of the dye (i.e., Red No. 102). On the other hand, in the inkjet ink B to which the predetermined viscosity modifier is added, the discoloration and fading (photochromic fading) of the printed image caused by light irradiation cannot be fully suppressed.

[0051] In contrast, the inkjet ink according to the present embodiment fixes the ink on the surface of the printed object by selecting the type and physical properties of the added viscosity modifier (i.e., reduced isomaltulose as a viscosity modifier with relatively high ink fixation) and the solvent, thereby sufficiently suppressing the photochromic fading of the printed image and improving the light resistance. The inventors have found that it is effective to fix the ink on the surface of the printed object (e.g., a tablet) in order to suppress the photochromic fading of the printed image. In this example, by fixing the ink on the surface 1S of the tablet, the specific dye 4 is fixed on the surface 1S, and as a result, the specific dye 4 can be left on the surface 1S at a high concentration.

[0052] In the case where the concentration of the specific dye 4 on the surface 1S of the substrate 1 of the tablet is high, for example, the proportion of the color material that undergoes photochromic fading due to photodecomposition among the specific dye 4 on the surface 1S is reduced. That is, even if a part of the specific dye 4 undergoes photochromic fading, the impact is limited, thereby suppressing the reduction in the visibility (readability) of the printed image. As a result, the visibility of the printed image as a whole can be maintained, and as a result, the photochromic fading of the printed image can be sufficiently suppressed. Therefore, the light resistance of the inkjet ink can be improved. In addition, the inventors have found that reduced isomaltulose, which has a relatively low solubility in water among the viscosity modifiers, functions as a fixing agent for fixing the ink containing Red No. 102 as a color material to the surface of the printed object.

[0053] Specifically, the inkjet ink of the present embodiment contains red No. 102 as a color material, i.e., an edible dye, and contains reduced isomaltulose having a solubility of less than 39 g in 100 ml of water at 20° C. as a viscosity modifier. According to such a configuration, the ink containing a specific tar-based pigment (red No. 102 in this example) used as a color material can be fixed on the surface of the printed object, so that the specific tar-based pigment remains on the surface at a high concentration. As a result, the inkjet ink of the present embodiment can fully suppress the photochromic fading of the printed image and improve the light resistance.

[0054] like Figure 1 As shown in (c), when inkjet ink C corresponding to the inkjet ink involved in this embodiment is printed on the surface 1S of the substrate 1 of the tablet, the specific dye 4 (here, red No. 102) in the ink is fixed to the surface 1S. Specifically, when the inkjet ink C is printed, the penetration depth Z (μm) of the specific dye 4 after a certain time from the start of printing is further reduced compared to the penetration depth Y of the specific dye 4 in the inkjet ink B containing a predetermined sugar (Y>Z). For example, the penetration depth Z of the specific dye 4 in the inkjet ink C is reduced to about 50% of the penetration depth Y of the specific dye 4 in the inkjet ink B. That is, the inkjet ink C can further suppress the penetration of the specific dye 4. Therefore, the specific dye 4 remains on the surface 1S at a high concentration, and the reduction in the visibility of the printed image is suppressed as described above. As a result, the photochromic fading of the printed image can be fully suppressed, and the inkjet ink C can improve the light resistance.

[0055] On the other hand, in the inkjet ink B, although the specific dye 4 can be left inside the tablet substrate 1 near the surface 1S, the penetration of the specific dye 4 is not sufficiently suppressed, and the ink cannot be fixed on the surface 1S. That is, in the inkjet ink B, the concentration of the specific dye 4 remaining on the surface 1S is low, so the photochromic fading of the printed image cannot be sufficiently suppressed, and the light resistance cannot be improved.

[0056] Thus, the inkjet ink according to the present embodiment can significantly suppress the penetration of a specific tar-based pigment (Red No. 102) into the printed material by adding reduced isomaltulose as a viscosity modifier having ink fixation, thereby fixing the ink on the surface of the printed material. Thus, the inkjet ink according to the present embodiment can suppress the photochromic fading of the printed image and improve the light resistance, and further suppress the discoloration and fading of the printed image caused by the penetration of the specific tar-based pigment into the printed material.

[0057] In addition, if Figure 1As shown in (c), the inkjet ink C can be fixed on the surface 1S of the tablet substrate 1 in a slightly raised manner. Therefore, for example, when the inkjet ink C is printed, the printed characters are recognized in a manner that they are deeply exposed on the surface 1S. Therefore, for example, in the inkjet ink C, the visibility of the printed image during printing can be improved compared with the inkjet inks A and B. That is, in the inkjet ink involved in this embodiment, not only the reduction in visibility caused by photochromic fading of the printed image is reduced, but also good visibility can be given to the printed image during printing.

[0058] Hereinafter, the light resistance of the inkjet ink according to the present embodiment will be described in detail.

[0059] The inkjet ink involved in this embodiment only needs to have a color difference ΔE of 20 or less in JIS Z 8781 before and after the light resistance test. Here, the light resistance test is, for example, the following test: with respect to the printed image obtained by printing using the inkjet ink involved in this embodiment, the color difference ΔE (value according to JIS Z8781) representing the change in chromaticity and optical color density before and after visible light irradiation is compared. Specifically, the color difference ΔE before and after the printed image is irradiated with a cumulative visible light of 1.2 million lux is measured and the values ​​are compared. The irradiation of visible light is performed using, for example, a light stability tester (Nagano Science LT-120A-WD). In addition, the printed image in the light resistance test is, for example, an image obtained by solid printing on a tablet (e.g., a film-coated tablet) as a printing object.

[0060] Sufficient light resistance required for forming a printed image on a medical tablet or the like usually refers to the case where the color difference ΔE of the printed image before and after visible light irradiation is 20 or less in a light resistance test of irradiating visible light of 1.2 million lux. The determination standard of sufficient light resistance is that the color difference ΔE is 20 or less, which is derived from the results of opinion tests conducted by the inventors together with various medical personnel. When the color difference ΔE exceeds 20, the visibility of the printed image (for example, the readability of the printed text) begins to decrease. That is, if the color difference ΔE before and after visible light irradiation is 20 or less, photochromic fading is sufficiently suppressed, and it can be considered that the inkjet ink has excellent light resistance. It should be noted that although this is a number larger than the color difference ΔE standard of 3 to 6 on ordinary commercial printed materials, the tablets before and after exposure are usually not compared, and it is assumed that the printed image on the surface of the tablet fades naturally, so this number can be obtained.

[0061] Hereinafter, each component constituting the inkjet ink according to the present embodiment will be described.

[0062] (color material)

[0063] As described above, the inkjet ink of this embodiment contains Red No. 102 as an edible dye. Red No. 102 is an edible tar-based dye, and Red No. 102 is also called New Coccine.

[0064] In the inkjet ink of the present embodiment, the mixing ratio of Red No. 102, i.e., the content of Red No. 102, is within the range of 0.5 mass % to 3.0 mass % relative to the mass of the entire ink. According to such a configuration, it is possible to impart good visibility to the printed image and impart excellent ejection stability (i.e., excellent intermittent recovery). In addition, if the content of Red No. 102 is within the above range, by adding reduced isomaltulose as a viscosity modifier having relatively high ink fixation, it is possible to reliably make Red No. 102 remain on the surface of the printed material at a high concentration, thereby suppressing photochromic fading of the printed image and reliably improving the light resistance of the inkjet ink of the present embodiment.

[0065] On the other hand, when the content of Red No. 102 is less than 0.5 mass %, the overall printed color becomes thinner and the visibility of the printed image tends to decrease. In addition, when the content of Red No. 102 is less than 0.5 mass %, the light resistance of the printed tablet may decrease or fail to exhibit light resistance when stored.

[0066] When the content of Red No. 102 exceeds 3.0% by mass, the solubility stability of the colorant deteriorates, and the pigment in the ink precipitates or precipitates as a solid, which may clog the nozzles of the inkjet head during printing and reduce the ejection stability.

[0067] In addition, the content of Red No. 102 is more preferably in the range of 1.0 mass % to 2.5 mass % relative to the mass of the entire ink, and further preferably in the range of 1.0 mass % to 1.6 mass %. According to such a configuration, better visibility can be imparted to the printed image, and more excellent ejection stability can be imparted.

[0068] It should be noted that the inkjet ink of the present embodiment may also contain a pigment (color material) other than the above-mentioned specific tar-based pigment, that is, red No. 102. The pigment other than red No. 102 is edible as long as it is not particularly limited. The pigment that can be added to the inkjet ink of the present embodiment can be appropriately selected and added from existing known synthetic food colorings, natural food colorings, for example. In addition, when the inkjet ink involved in the present embodiment contains a color material other than red No. 102 as an edible dye, the total content of the edible dye other than red No. 102 is preferably in the range of less than 0.6 mass %, more preferably in the range of less than 0.4 mass %, and further preferably in the range of less than 0.3 mass %. If the total content of the edible dye other than red No. 102 is within the above range, the light resistance of the inkjet ink can be improved, the printed image is given good visibility, and the inkjet ink is given sufficient ejection stability.

[0069] As synthetic food coloring, for example, tar-based coloring, natural coloring derivatives, natural synthetic coloring, etc. can be listed. As tar-based coloring, for example, edible red No. 2, edible red No. 3, edible red No. 40, edible red No. 104, edible red No. 105, edible red No. 106, edible yellow No. 4, edible yellow No. 5, edible blue No. 1, edible blue No. 2, edible red No. 2 aluminum lake, edible red No. 3 aluminum lake, edible red No. 40 aluminum lake, edible yellow No. 4 aluminum lake, edible No. 5 aluminum lake, edible blue No. 1 aluminum lake, edible blue No. 2 aluminum lake, etc. As natural coloring derivatives, for example, norbixin potassium, etc. can be listed. As natural synthetic coloring, for example, beta-carotene, riboflavin, etc. can be listed.

[0070] In addition, as natural food coloring, for example, anthocyanin pigments, carotenoid pigments, quinone pigments, chlorophyll pigments, flavonoid pigments, betaine pigments, Monascus pigments, and other pigments derived from natural products can be listed. As anthocyanin pigments, for example, carrot pigments, red cabbage pigments, red rice pigments, elderberry pigments, bilberry pigments, gooseberry pigments, cranberry pigments, salmon berry pigments, perilla pigments, sim blueberry pigments, strawberry pigments, dark sweet cherry pigments, cherry pigments, hibiscus pigments, cranberry pigments, grape juice pigments, grape skin pigments, blackcurrant pigments, blackberry pigments, blueberry pigments, plum pigments, bilberry pigments, boysenberry pigments, mulberry pigments, purple potato pigments, purple corn pigments, purple yam pigments, raspberry pigments, red currant pigments, loganberry pigments, and other anthocyanin pigments can be listed. As carotenoid pigments, for example, carmine pigments, gardenia yellow pigments, and other carotenoid pigments can be listed. As quinone pigments, for example, carmine, lithospermum pigment, lac pigment, and other quinone pigments can be cited. As flavonoid pigments, for example, safflower yellow, sorghum pigment, onion pigment, and other flavonoid pigments can be cited. As betaine pigments, for example, betaine can be cited. As Monascus pigments, for example, Monascus pigment and Monascus yellow can be cited. As other pigments derived from natural products, for example, curcumin, stinking sterculine pigment, gardenia red pigment, spirulina blue pigment, etc. can be cited.

[0071] (Viscosity modifier)

[0072] As described above, the inkjet ink involved in the present embodiment contains a viscosity modifier having ink fixation properties that allows the ink containing a specific tar-based pigment (Red No. 102) to be fixed on the surface of the printed object. Specifically, the viscosity modifier contained in the inkjet ink involved in the present embodiment is reduced isomaltulose, and the solubility of reduced isomaltulose in 100 ml of water at 20°C is 38g. If the viscosity modifier is of this structure, the ink containing Red No. 102 can be fully fixed on the surface of the printed object. As a result, the inkjet ink of the present embodiment can fully suppress the photochromic fading of the printed image and improve the light resistance. In addition, the reduced isomaltulose used as a viscosity modifier in the present embodiment itself also has the function of suppressing the decomposition (photodecomposition) of the inkjet ink due to light irradiation. Therefore, the occurrence of photochromic fading itself can also be suppressed.

[0073] Furthermore, by adding reduced isomaltulose as a viscosity modifier to the inkjet ink, the viscosity of the inkjet ink can be easily adjusted, and the discharge stability can be improved.

[0074] The mixing ratio of reduced isomaltulose in the inkjet ink according to the present embodiment, i.e., the content of reduced isomaltulose relative to the mass of the entire ink, is preferably in the range of 3.0 mass % to 8.5 mass %. According to such a configuration, the fixing effect of reduced isomaltulose on the ink can be more reliably exerted, and the light resistance of the inkjet ink can be reliably improved. In addition, the inkjet ink according to the present embodiment can be given high ejection stability.

[0075] In contrast, when the mixing ratio of reduced isomaltulose is less than 3.0% by mass, the fixing effect of the ink is reduced, and the light resistance is sometimes reduced. In addition, when the mixing ratio of reduced isomaltulose is less than 3.0% by mass, the ink droplets ejected may not land at the desired position due to insufficient viscosity of the ink (i.e., the landing accuracy of the ink droplets is reduced). In addition, when the mixing ratio of reduced isomaltulose exceeds 8.5% by mass, the ink viscosity increases or reduced isomaltulose precipitates on the nozzle surface, which causes the nozzle of the inkjet head to be clogged during printing, and the ejection stability may be reduced.

[0076] It should be noted that the mixing ratio of reduced isomaltulose is more preferably in the range of 4.0 mass % to 8.0 mass % relative to the mass of the entire ink, and is further preferably in the range of 5.0 mass % to 8.0 mass % relative to the mass of the entire ink. According to such a configuration, the fixing effect of reduced isomaltulose on the ink can be more reliably exerted, and the light resistance of the inkjet ink can be reliably improved. In addition, the inkjet ink involved in this embodiment can be given higher ejection stability.

[0077] The viscosity of the inkjet ink involved in this embodiment, that is, the viscosity of the inkjet ink to which reduced isomaltulose is added as a viscosity modifier, is preferably in the range of 1.0 mPa·s to 7.0 mPa·s. According to such a configuration, it is possible to impart appropriate viscosity to the ink, so that the ejected ink droplets can be landed at a desired position (that is, the landing accuracy of the ink droplets can be improved).

[0078] On the other hand, when the viscosity of the inkjet ink is less than 1.0 mPa·s, the ink droplets ejected may not land at the desired position due to the low viscosity of the ink (i.e., the landing accuracy of the ink droplets is reduced). In addition, when the viscosity of the inkjet ink exceeds 7.0 mPa·s, the ink droplets may be difficult to eject due to the high viscosity of the ink.

[0079] It should be noted that the viscosity of the inkjet ink is more preferably in the range of 2.0 mPa·s to 6.0 mPa·s, further preferably in the range of 2.0 mPa·s to 5.0 mPa·s, and most preferably in the range of 2.5 mPa·s to 3.5 mPa·s. With such a configuration, the landing accuracy of the ink droplets can be further improved.

[0080] (Viscosity measurement method)

[0081] The viscosity of the ink is measured at a measurement temperature of 25° C. using, for example, a rotational viscometer.

[0082] In addition, the viscosity of the ink in this embodiment is a value measured at a measurement temperature of 25° C. using a rotational viscometer.

[0083] In addition, the ratio of the mass of reduced isomaltulose to the mass of Red No. 102 in the inkjet ink according to the present embodiment (reduced isomaltulose / Red No. 102) is preferably in the range of 2.3 to 6.5, more preferably in the range of 3.1 to 6.1, and further preferably in the range of 3.8 to 6.1. According to such a configuration, the fixing effect of reduced isomaltulose on the ink can be more reliably exerted, and the light resistance of the inkjet ink can be reliably improved. In addition, high ejection stability can be imparted to the inkjet ink according to the present embodiment.

[0084] On the other hand, when the above ratio (reduced isomaltulose / Red No. 102) is less than 2.3, the fixing effect of the ink may be reduced. In addition, when the above ratio (reduced isomaltulose / Red No. 102) is less than 2.3, the light resistance is reduced when the printed tablet is stored, or the light resistance may not be exerted. In addition, when the above ratio (reduced isomaltulose / Red No. 102) is less than 2.3, the viscosity of the ink is insufficient, and the ejected ink droplets may not land at the desired position (that is, the landing accuracy of the ink droplets is reduced).

[0085] When the ratio (reduced isomaltulose / Red No. 102) exceeds 6.5, the ink viscosity increases or reduced isomaltulose precipitates on the nozzle surface, which may cause nozzle clogging of the inkjet head during printing and may reduce ejection stability.

[0086] As described above, by setting the amount of reduced isomaltulose added to the inkjet ink within a specific numerical range, both light resistance and ejection stability can be improved.

[0087] The following describes the mechanism for improving discharge stability.

[0088] Reduced isomaltulose added to inkjet ink also has the function of forming a coating at the ink interface on the nozzle surface of an inkjet device such as an inkjet printer, thereby preventing solvent evaporation. In addition, during the ink ejection operation caused by the piezoelectricity of the inkjet device, the coating has the characteristic of being easily disintegrated and then dissolved again.

[0089] Therefore, by adding reduced isomaltulose to the inkjet ink, changes in the physical properties of the ink near the nozzle surface of the inkjet device can be suppressed, and stable ejection can be achieved. As a result, the ejection stability of the inkjet ink to which reduced isomaltulose is added is improved.

[0090] (Solvent)

[0091] In addition to the above-mentioned specific tar-based pigment (Red No. 102) and the above-mentioned viscosity modifier (reduced isomaltulose), the inkjet ink involved in this embodiment also contains a solvent (dispersion medium) for dissolving (dispersing) the specific tar-based pigment and the viscosity modifier. In the inkjet ink involved in this embodiment, as a solvent, it contains water (e.g., purified water); at least one of ethanol, n-propanol (NPA) and isopropanol (IPA), i.e., a monohydric alcohol; and at least one of glycerol and propylene glycol (PG), i.e., a wetting agent.

[0092] Generally, reduced isomaltulose has the property of being insoluble in alcohols. Therefore, in the present embodiment, by including at least one of ethanol, n-propanol and isopropanol, i.e., a monohydric alcohol, and at least one of glycerol and propylene glycol, i.e., a wetting agent (polyol), in the solvent, the solubility of reduced isomaltulose relative to the solvent is reduced. Therefore, in the inkjet ink involved in the present embodiment, the fixing effect of reduced isomaltulose on the ink can be further improved, so that the above-mentioned specific tar-based pigment (in this case, red No. 102) contained in the ink remains on the surface of the printed object (e.g., a tablet) at a higher concentration. Thus, the light resistance of the inkjet ink of the present embodiment can be further improved.

[0093] In addition, glycerol and propylene glycol function as wetting agents, which can prevent the ink from drying at the inkjet nozzle, thereby giving the ink sufficient ejection stability. In addition, ethanol, n-propanol, and isopropanol are particularly volatile, so the transfer resistance (drying property) of the inkjet ink can be improved. In addition to water, by adding the above alcohols to the solvent, the light resistance of the inkjet ink can be further improved, and the inkjet ink can be given properties corresponding to each component.

[0094] In the inkjet ink of the present embodiment, the mixing ratio of the monohydric alcohol, i.e., the content of the monohydric alcohol, is within a range of 30% by mass to 60% by mass relative to the mass of the entire ink. With such a configuration, the ink can be given excellent drying properties. In addition, if the content of the monohydric alcohol is within the above range, the ink can be given a moderate viscosity, so that the ejected ink droplets can be landed at a desired position (i.e., the landing accuracy of the ink droplets can be improved).

[0095] In contrast, when the content of the monohydric alcohol is less than 30% by mass, the drying properties of the ink tend to decrease.

[0096] On the other hand, when the content of the monohydric alcohol exceeds 60% by mass, the drying of the nozzle liquid surface is accelerated, and the nozzles of the inkjet head are clogged during printing, so that the discharge stability may be reduced.

[0097] In addition, the content of the monohydric alcohol is more preferably in the range of 35 mass % to 55 mass % relative to the mass of the entire ink, and further preferably in the range of 35 mass % to 50 mass %. According to such a configuration, the drying property of the ink can be reliably maintained and excellent ejection stability can be imparted.

[0098] In addition, in the inkjet ink involved in the present embodiment, the proportion of each component of the above-mentioned solvent is not limited, but the proportion of the above-mentioned wetting agent, that is, the amount of the wetting agent added, is within the range of 0.05 mass % or more and 10 mass % or less relative to the mass of the entire ink. According to such a structure, the solubility of reduced isomaltulose relative to the solvent is reliably reduced, and the fixing effect of the ink containing the above-mentioned specific tar-based pigment is further improved. Therefore, it is possible to give the inkjet ink more excellent light resistance. In addition, according to the above-mentioned structure, it is possible to prevent the nozzle liquid surface from drying, so that the ejection stability can be improved.

[0099] On the other hand, when the amount of the wetting agent added is less than 0.05% by mass, the effect of reducing the solubility of reduced isomaltulose in the solvent is reduced, and the fixing effect may be reduced. In addition, when the amount of the wetting agent added is less than 0.05% by mass, the drying of the nozzle liquid surface is promoted, and the discharge stability may be reduced.

[0100] In addition, when the amount of wetting agent added exceeds 10% by mass, the proportion of monohydric alcohol in the entire ink is relatively reduced, so the drying delay of the printed surface on the tablet surface increases, sometimes leading to such an undesirable situation (poor transfer): when the printed tablets come into contact with each other, the undried ink adheres to the other tablet and causes contamination.

[0101] It should be noted that the mixing ratio of the wetting agent, i.e., the amount of the wetting agent added, relative to the total mass of the ink is preferably in the range of 0.05 mass % to 6 mass %, and more preferably in the range of 0.05 mass % to 4 mass %. According to such a configuration, the drying property of the ink can be reliably maintained, and excellent ejection stability can be imparted.

[0102] (Resin added inside)

[0103] In addition to the above-mentioned pigment and solvent, the inkjet ink involved in the present embodiment may also contain an internally added resin. The internally added resin that can be added to the inkjet ink involved in the present embodiment is an edible and water-soluble powder, slurry, or flaky resinous substance, as long as it is a substance that can form a film on the surface of the tablet by drying after printing. As the above-mentioned internally added resin, for example, polyvinyl alcohol (PVA), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), polyvinyl pyrrolidone (PVP), high molecular weight polyethylene glycol (PEG) such as polyethylene glycol 4000 / polyethylene glycol 1540, shellac resin, methacrylic acid copolymer (product name: Eudragit S100), maltodextrin, erythritol, etc. can be listed.

[0104] (Leveling agent)

[0105] In addition to the above-mentioned pigment, solvent or internal added resin, the inkjet ink involved in this embodiment may also contain a leveling agent. The leveling agent that can be added to the inkjet ink involved in this embodiment can be any edible water-soluble surfactant. As the above-mentioned leveling agent, for example, polyglycerol fatty acid esters (for example, distearic acid decaglycerol Q-182S manufactured by Sun Chemical Co., Ltd., monolauric acid decaglycerol Q-12S manufactured by the same company), sorbitan fatty acid esters (for example, NIKKOLSL-10 manufactured by Nikko Chemicals Co., Ltd.), sucrose fatty acid esters (for example, DK Ester F-110 manufactured by Daiichi Industrial Pharmaceutical Co., Ltd.), polysorbates (Emazole S-120 series manufactured by Kao Corporation), etc.

[0106] 〔Printing method〕

[0107] The printing method of the inkjet ink involved in the present embodiment is not particularly limited, and printing using an inkjet device such as a commercially available inkjet printer may be used. Therefore, the inkjet ink involved in the present embodiment has a wide range of applications and is very useful. For example, the inkjet ink involved in the present embodiment may be printed by a so-called drop-on-demand inkjet device using a piezoelectric element (piezoelectric ceramic) as an actuator, or may be printed by an inkjet device of another type.

[0108] As drop-on-demand inkjet devices, for example, there can be cited: devices using a thermal inkjet method that uses water vapor pressure to eject inkjet ink, and the water vapor pressure is generated by instantaneously heating a micro heating element to a high temperature (200 to 300° C.); electrostatic devices that eject inkjet ink by electrostatically vibrating an actuator; ultrasonic devices that use cavitation phenomena using ultrasonic waves, etc. In addition, if the inkjet ink involved in this embodiment has charging performance, a device using a continuous jet type (continuous method) can also be used.

[0109] 〔tablet〕

[0110] In this embodiment, the inkjet ink of this embodiment can be used to print characters or images on the surface of (for example) a tablet using the above-mentioned printing method. That is, the tablet of this embodiment only needs to have a printed portion, that is, a printed image, obtained by printing using the inkjet ink of this embodiment. If it is the inkjet ink of this embodiment, for example, the light resistance of the printed image applied to the surface of the medical tablet using the inkjet printing method can be improved. The following describes the structure of a tablet having a printed image printed using the inkjet ink of the embodiment.

[0111] The tablets involved in this embodiment are, for example, medical tablets. Here, in addition to (for example) plain tablets (bare tablets), sugar-coated tablets, enteric-coated tablets, orally disintegrating tablets, etc., "medical tablets" also include film-coated tablets having a water-soluble surface layer formed on the outermost surface of the tablet.

[0112] Figure 2 This is a schematic cross-sectional view showing an example of a printed (character or image) medical tablet (plain tablet). Figure 2 A plain printed material 5 having a printed image 3 such as characters printed on an upper surface of a tablet substrate 1 is shown in a cross-sectional view.

[0113] Figure 3 This is a schematic cross-sectional view showing an example of a printed (text, graphic) medical tablet (film-coated tablet). Figure 3 A film-coated tablet printed material 9 is shown in a cross-sectional view, wherein a printed image 3 such as characters is printed on an upper surface of a tablet substrate 1 having a film coating layer 7 formed on the surface.

[0114] It should be noted that, in this embodiment, Figure 4 As shown, a solid image can be printed as a plain printed image 11, such as Figure 5 As shown, a two-dimensional barcode may be printed as the printed image 13 of the film-coated tablet.

[0115] The active ingredients contained in the medical tablets are not particularly limited. For example, substances effective for the prevention / treatment of various diseases (for example, substances having sleep induction effect, tranquilizer activity, antibacterial activity, hypotensive effect, antihypertensive activity, analgesic effect, anti-inflammatory activity, mental stabilizing effect, diabetes therapeutic activity, diuretic effect, anticholinergic activity, anti-gastric acid effect, anti-epileptic effect, ACE inhibitory activity, β-receptor antagonist or agonist activity, anesthetic effect, appetite suppressant effect, antiarrhythmic effect, antidepressant effect, anticoagulant activity, antidiarrheal effect, antihistamine activity, antimalarial effect, antitumor activity, immunosuppressive activity, anti-Parkinson's disease effect, antipsychotic effect, antiplatelet activity, antihyperlipidemic effect, etc.), substances having a cleaning effect, fragrances, substances having a deodorizing effect, etc., are contained, but are not limited to these.

[0116] As required, the tablets involved in the present embodiment can be matched with the carriers allowed in their use together with the active ingredients. For example, if it is a medical tablet, a pharmaceutically acceptable carrier can be matched. As pharmaceutically acceptable carriers, various organic or inorganic carrier substances commonly used as preparation raw materials can be used, such as appropriate and appropriate amounts of excipients, lubricants, binders, disintegrants, tackifiers, etc. In addition, additives such as preservatives, antioxidants, colorants, sweeteners, etc. can also be used as required.

[0117] In this embodiment, a medical tablet is cited as an example for explanation, but the present invention is not limited thereto. There is no particular limitation on the printing object of the inkjet ink involved in this embodiment, and for example, it can be printed on the surface of various tablets such as tablets administered to animals other than humans (pets, livestock, poultry, etc.), feed, fertilizer, detergent, lemon-flavored candy and other tablet-shaped snacks or health products and other foods. In addition, there is no particular limitation on the size of the printing object of the inkjet ink involved in this embodiment, and it can be applied to tablets of various sizes.

[0118] (Effects of this embodiment)

[0119] (1) The inkjet ink involved in this embodiment contains Red No. 102, reduced isomaltulose, water as a solvent, a monohydric alcohol, and a wetting agent, the monohydric alcohol contains at least one of ethanol, NPA and IPA, and the wetting agent contains at least one of glycerol and PG. The mixing ratio of Red No. 102 is in the range of 0.5 mass% to 3.0 mass% with respect to the total mass of the inkjet ink, the mixing ratio of the monohydric alcohol is in the range of 30 mass% to 60 mass% with respect to the total mass of the inkjet ink, and the mixing ratio of the wetting agent is in the range of 0.05 mass% to 10 mass% with respect to the total mass of the inkjet ink.

[0120] According to such a configuration, drying properties, light resistance, and discharge stability can be achieved.

[0121] (2) The amount of reduced isomaltulose contained in the inkjet ink according to the present embodiment may be in the range of 3.0% by mass or more and 8.5% by mass or less relative to the total mass of the inkjet ink.

[0122] According to such a configuration, light resistance and discharge stability can be further improved.

[0123] (3) The viscosity of the inkjet ink according to the present embodiment may be within a range of 1.0 mPa·s to 7.0 mPa·s.

[0124] According to such a configuration, appropriate viscosity can be imparted to the ink, so that the ejected ink droplets can be landed at desired positions (that is, the landing accuracy of the ink droplets can be improved).

[0125] (4) The tablet according to the present embodiment includes a printed image (an example of a printed portion) 3 printed using the above-mentioned inkjet ink.

[0126] According to such a configuration, photochromic fading of the printed image 3 directly printed on the surface of the tablet can be sufficiently suppressed, and the light resistance of the printed image 3 can be sufficiently improved. In addition, the printed image portion printed on the tablet surface can be made edible.

[0127] [Example]

[0128] <Example 1>

[0129] Hereinafter, the preparation procedure of the inkjet ink of Example 1 will be described.

[0130] (Manufacture of inkjet ink)

[0131] First, prepare printing ink. Inkjet ink contains the components of pigment (color material), solvent, wetting agent, and viscosity modifier (reduced isomaltulose). As the preparation order, first add the wetting agent and viscosity modifier (reduced isomaltulose) to the solvent to obtain a transparent base liquid. Then, add the pigment to the transparent base liquid. In this way, the ink involved in this embodiment is prepared. Below, various components are specifically described.

[0132] In Examples 1 to 30 and Comparative Examples 1 to 12, purified water (ion-exchanged water), ethanol, n-propanol (NPA: 1-propanol), and isopropanol (IPA: 2-propanol) were used as solvents, respectively, as necessary.

[0133] In Examples 1 to 30 and Comparative Examples 1 to 12, glycerin and PG (propylene glycol) were used as a wetting agent, respectively, as necessary.

[0134] In this embodiment, at least one of ethanol, NPA and IPA, and at least one of glycerol and PG are added to purified water and stirred thoroughly to obtain a solvent (mixed solvent). In addition, reduced isomaltulose is added to the above-mentioned solvent as a viscosity modifier, and stirred for about 1 hour to obtain a transparent base liquid. In the above-mentioned transparent base liquid, food dyes, namely red No. 102, red No. 3, yellow No. 4 and blue No. 1, as color materials, are added to obtain the inkjet ink of Example 1. With respect to the entire inkjet ink of Example 1, the proportion of red No. 102 as a color material is set to 0.50 mass%, the proportion of red No. 3 is set to 0.03 mass%, the proportion of yellow No. 4 is set to 0.03 mass%, the proportion of blue No. 1 is set to 0.03 mass%, the proportion of purified water in the solvent is set to 52.96 mass%, the proportion of ethanol is set to 40.0 mass%, the proportion of propylene glycol (PG) is set to 0.1 mass%, and the proportion of reduced isomaltulose as a viscosity modifier is set to 6.35 mass%.

[0135] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 1 was adjusted to 12.7.

[0136] <Example 2>

[0137] In this example, the mixing ratio of red No. 102 was set to 1.0 mass %, the mixing ratio of red No. 3 was set to 0.06 mass %, the mixing ratio of yellow No. 4 was set to 0.06 mass %, the mixing ratio of blue No. 1 was set to 0.06 mass %, and the mixing ratio of purified water was set to 52.37 mass % relative to the entire inkjet ink. Inkjet ink of Example 2 was obtained in the same manner as in Example 1 except for the above.

[0138] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 2 was adjusted to 6.4.

[0139] <Example 3>

[0140] In this example, the inkjet ink of Example 3 was obtained in the same manner as in Example 1 except that the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, and the mixing ratio of purified water was 52.00 mass %.

[0141] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 3 was adjusted to 4.8.

[0142] <Example 4>

[0143] In this example, the mixing ratio of red No. 102 was set to 1.60 mass %, the mixing ratio of red No. 3 was set to 0.10 mass %, the mixing ratio of yellow No. 4 was set to 0.10 mass %, the mixing ratio of blue No. 1 was set to 0.10 mass %, and the mixing ratio of purified water was set to 51.65 mass %. Inkjet ink of Example 4 was obtained in the same manner as in Example 1 except for the above.

[0144] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 4 was adjusted to 4.0.

[0145] <Example 5>

[0146] In this example, the mixing ratio of red No. 102 was set to 2.50 mass %, the mixing ratio of red No. 3 was set to 0.15 mass %, the mixing ratio of yellow No. 4 was set to 0.15 mass %, the mixing ratio of blue No. 1 was set to 0.15 mass %, and the mixing ratio of purified water was set to 50.60 mass %. Inkjet ink of Example 5 was obtained in the same manner as in Example 1 except for the above.

[0147] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 5 was adjusted to 2.5.

[0148] <Example 6>

[0149] In this example, the mixing ratio of red No. 102 was set to 3.00 mass %, the mixing ratio of red No. 3 was set to 0.18 mass %, the mixing ratio of yellow No. 4 was set to 0.18 mass %, the mixing ratio of blue No. 1 was set to 0.18 mass %, and the mixing ratio of purified water was set to 50.01 mass %. Inkjet ink of Example 6 was obtained in the same manner as in Example 1 except for the above.

[0150] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 6 was adjusted to 2.1.

[0151] <Example 7>

[0152] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 62.00 mass %, and the mixing ratio of ethanol was set to 30.0 mass %, relative to the entire inkjet ink. Inkjet ink of Example 7 was obtained in the same manner as in Example 1 except for the above.

[0153] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 7 was adjusted to 4.8.

[0154] <Example 8>

[0155] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 57.00 mass %, and the mixing ratio of ethanol was set to 35.0 mass %, relative to the entire inkjet ink. Inkjet ink of Example 8 was obtained in the same manner as in Example 1 except for the above.

[0156] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 8 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0157] <Example 9>

[0158] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 42.00 mass %, and the mixing ratio of ethanol was set to 50.0 mass %. Inkjet ink of Example 9 was obtained in the same manner as in Example 1 except for the above.

[0159] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 9 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0160] <Example 10>

[0161] In this example, the inkjet ink of Example 10 was obtained in the same manner as in Example 1 except that the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 37.00 mass %, and the mixing ratio of ethanol was 55.0 mass % relative to the entire inkjet ink.

[0162] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 10 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0163] <Example 11>

[0164] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 32.00 mass %, and the mixing ratio of ethanol was set to 60.0 mass %, relative to the entire inkjet ink. Inkjet ink of Example 11 was obtained in the same manner as in Example 1 except for the above.

[0165] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 11 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0166] <Example 12>

[0167] In this example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 52.00 mass %, and the mixing ratio of NPA instead of ethanol was set to 40.0 mass %. Inkjet ink of Example 12 was obtained in the same manner as in Example 1 except for the above.

[0168] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 12 was adjusted to 4.8.

[0169] <Example 13>

[0170] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 52.00 mass %, and the mixing ratio of IPA instead of ethanol was set to 40.0 mass %. Inkjet ink of Example 13 was obtained in the same manner as in Example 1 except for the above.

[0171] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 13 was adjusted to 4.8.

[0172] <Example 14>

[0173] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 52.00 mass %, the mixing ratio of ethanol was set to 35.0 mass %, and the mixing ratio of NPA was set to 5.0 mass %. Inkjet ink of Example 14 was obtained in the same manner as in Example 1 except for the above.

[0174] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 14 was adjusted to 4.8.

[0175] <Example 15>

[0176] In this example, the mixing ratio of red No. 102 was set to 1.31 mass %, the mixing ratio of red No. 3 was set to 0.08 mass %, the mixing ratio of yellow No. 4 was set to 0.08 mass %, the mixing ratio of blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 52.00 mass %, the mixing ratio of ethanol was set to 35.0 mass %, and the mixing ratio of IPA was set to 5.0 mass %. Inkjet ink of Example 15 was obtained in the same manner as in Example 1 except for the above.

[0177] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 15 was adjusted to 4.8.

[0178] <Example 16>

[0179] In this example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 52.05 mass %, and the mixing ratio of PG was set to 0.05 mass %. Inkjet ink of Example 16 was obtained in the same manner as in Example 1 except for the above.

[0180] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 16 was adjusted to 4.8.

[0181] <Example 17>

[0182] In this example, the mixing ratio of Red No. 102 was set to 1.31 mass %, Red No. 3 was set to 0.08 mass %, Yellow No. 4 was set to 0.08 mass %, Blue No. 1 was set to 0.08 mass %, purified water was set to 48.10 mass %, and PG was set to 4.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 17 was obtained in the same manner as in Example 1 except for the above.

[0183] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 17 was adjusted to 4.8.

[0184] <Example 18>

[0185] In this example, the mixing ratio of Red No. 102 was set to 1.31 mass %, Red No. 3 was set to 0.08 mass %, Yellow No. 4 was set to 0.08 mass %, Blue No. 1 was set to 0.08 mass %, purified water was set to 46.10 mass %, and PG was set to 6.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 18 was obtained in the same manner as in Example 1 except for the above.

[0186] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 18 was adjusted to 4.8.

[0187] <Example 19>

[0188] In this example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 42.10 mass %, and the mixing ratio of PG was set to 10.00 mass %. Inkjet ink of Example 19 was obtained in the same manner as in Example 1 except for the above.

[0189] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 19 was adjusted to 4.8.

[0190] <Example 20>

[0191] In this example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 52.00 mass %, and the mixing ratio of glycerol instead of PG was set to 0.10 mass %. Inkjet ink of Example 20 was obtained in the same manner as in Example 1 except for the above.

[0192] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 20 was adjusted to 4.8.

[0193] <Example 21>

[0194] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 55.85 mass %, and reduced isomaltulose was 2.50 mass %, relative to the entire inkjet ink. Inkjet ink of Example 21 was obtained in the same manner as in Example 1 except for the above.

[0195] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 21 was adjusted to 1.9.

[0196] <Example 22>

[0197] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 55.35 mass %, and reduced isomaltulose was 3.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 22 was obtained in the same manner as in Example 1 except for the above.

[0198] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 22 was adjusted to 2.3.

[0199] <Example 23>

[0200] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 54.35 mass %, and the mixing ratio of reduced isomaltulose was 4.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 23 was obtained in the same manner as in Example 1 except for the above.

[0201] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 23 was adjusted to 3.1.

[0202] <Example 24>

[0203] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 53.35 mass %, and reduced isomaltulose was 5.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 24 was obtained in the same manner as in Example 1 except for the above.

[0204] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 24 was adjusted to 3.8.

[0205] <Example 25>

[0206] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 51.35 mass %, and reduced isomaltulose was 7.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 25 was obtained in the same manner as in Example 1 except for the above.

[0207] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 25 was adjusted to 5.3.

[0208] <Example 26>

[0209] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 50.35 mass %, and reduced isomaltulose was 8.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 26 was obtained in the same manner as in Example 1 except for the above.

[0210] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 26 was adjusted to 6.1.

[0211] <Example 27>

[0212] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 49.85 mass %, and reduced isomaltulose was 8.50 mass %, relative to the entire inkjet ink. Inkjet ink of Example 27 was obtained in the same manner as in Example 1 except for the above.

[0213] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 27 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 6.5.

[0214] <Example 28>

[0215] In this example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 40.35 mass %, and reduced isomaltulose was 18.00 mass %, relative to the entire inkjet ink. Inkjet ink of Example 28 was obtained in the same manner as in Example 1 except for the above.

[0216] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 28 was adjusted to 13.7.

[0217] <Example 29>

[0218] In this example, the mixing ratio of Red No. 102 was 3.00 mass %, Red No. 3 was 0.18 mass %, Yellow No. 4 was 0.18 mass %, Blue No. 1 was 0.18 mass %, purified water was 27.86 mass %, ethanol was 60.00 mass %, and reduced isomaltulose was 8.50 mass %, relative to the entire inkjet ink. Inkjet ink of Example 29 was obtained in the same manner as in Example 1 except for the above.

[0219] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 29 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 2.8.

[0220] <Example 30>

[0221] In this example, with respect to the entire inkjet ink, the mixing ratio of Red No. 102 was set to 0.50 mass%, the mixing ratio of Red No. 3 was set to 0.03 mass%, the mixing ratio of Yellow No. 4 was set to 0.03 mass%, the mixing ratio of Blue No. 1 was set to 0.03 mass%, the mixing ratio of purified water was set to 56.41 mass%, the mixing ratio of ethanol was set to 30.00 mass%, the mixing ratio of PG was set to 10.00 mass%, and the mixing ratio of reduced isomaltulose was set to 3.00 mass. Except for this, the inkjet ink of Example 30 was obtained in the same manner as in Example 1.

[0222] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 30 was adjusted to 6.0.

[0223] <Example 31>

[0224] In this example, the inkjet ink of Example 31 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 0.50 mass % and the blending ratio of purified water was 53.05 mass % relative to the entire inkjet ink.

[0225] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 31 was adjusted to 12.7.

[0226] <Example 32>

[0227] In this example, the inkjet ink of Example 32 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.00 mass % and the blending ratio of purified water was 52.55 mass % relative to the entire inkjet ink.

[0228] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 32 was adjusted to 6.4.

[0229] <Example 33>

[0230] In this example, the inkjet ink of Example 33 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass % and the blending ratio of purified water was 52.24 mass % relative to the entire inkjet ink.

[0231] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 33 was adjusted to 4.8.

[0232] <Example 34>

[0233] In this example, the inkjet ink of Example 34 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.60 mass % and the blending ratio of purified water was 51.95 mass % relative to the entire inkjet ink.

[0234] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 34 was adjusted to 4.0.

[0235] <Example 35>

[0236] In this example, the inkjet ink of Example 35 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 2.50 mass % and the blending ratio of purified water was 51.05 mass % relative to the entire inkjet ink.

[0237] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 35 was adjusted to 2.5.

[0238] <Example 36>

[0239] In this example, the inkjet ink of Example 36 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 3.00 mass % and the blending ratio of purified water was 50.55 mass % relative to the entire inkjet ink.

[0240] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 36 was adjusted to 2.1.

[0241] <Example 37>

[0242] In this example, the inkjet ink of Example 37 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 57.24 mass %, and the blending ratio of ethanol was 35.00 mass % relative to the entire inkjet ink.

[0243] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 37 was adjusted to 4.8.

[0244] <Example 38>

[0245] In this example, the inkjet ink of Example 38 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 42.24 mass %, and the blending ratio of ethanol was 50.00 mass % relative to the entire inkjet ink.

[0246] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 38 was adjusted to 4.8.

[0247] <Example 39>

[0248] In this example, the inkjet ink of Example 39 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 52.29 mass %, and the blending ratio of PG was 0.05 mass % relative to the entire inkjet ink.

[0249] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 39 was adjusted to 4.8.

[0250] <Example 40>

[0251] In this example, the inkjet ink of Example 40 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 48.34 mass %, and the blending ratio of PG was 4.00 mass % relative to the entire inkjet ink.

[0252] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 40 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0253] <Example 41>

[0254] In this example, the inkjet ink of Example 41 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 53.59 mass %, and the blending ratio of reduced isomaltulose was 5.00 mass % relative to the entire inkjet ink.

[0255] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Example 41 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 3.8.

[0256] <Example 42>

[0257] In this example, the inkjet ink of Example 42 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 50.59 mass %, and the blending ratio of reduced isomaltulose was 8.00 mass % relative to the entire inkjet ink.

[0258] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 42 was adjusted to 6.1.

[0259] <Example 43>

[0260] In this example, the inkjet ink of Example 43 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 56.09 mass %, and the blending ratio of reduced isomaltulose was 2.50 mass % relative to the entire inkjet ink.

[0261] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 43 was adjusted to 1.9.

[0262] <Example 44>

[0263] In this example, the inkjet ink of Example 44 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 55.59 mass %, and the blending ratio of reduced isomaltulose was 3.00 mass % relative to the entire inkjet ink.

[0264] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 44 was adjusted to 2.3.

[0265] <Example 45>

[0266] In this example, the inkjet ink of Example 45 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 50.09 mass %, and the blending ratio of reduced isomaltulose was 8.50 mass % relative to the entire inkjet ink.

[0267] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 45 was adjusted to 6.5.

[0268] <Example 46>

[0269] In this example, the inkjet ink of Example 46 was obtained in the same manner as in Example 1 except that the blending ratio of Red No. 102 was 1.31 mass %, the blending ratio of purified water was 48.59 mass %, and the blending ratio of reduced isomaltulose was 10.00 mass % relative to the entire inkjet ink.

[0270] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Example 46 was adjusted to 7.6.

[0271] <Comparative Example 1>

[0272] In this comparative example, the mixing ratio of Red No. 102 was set to 0.30 mass %, the mixing ratio of Red No. 3 was set to 0.02 mass %, the mixing ratio of Yellow No. 4 was set to 0.02 mass %, the mixing ratio of Blue No. 1 was set to 0.02 mass %, and the mixing ratio of purified water was set to 53.19 mass % relative to the entire inkjet ink. Except for this, the inkjet ink of Comparative Example 1 was obtained in the same manner as in Example 1.

[0273] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 1 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 21.2.

[0274] <Comparative Example 2>

[0275] In this comparative example, the mixing ratio of Red No. 102 was set to 5.00 mass %, Red No. 3 was set to 0.31 mass %, Yellow No. 4 was set to 0.31 mass %, Blue No. 1 was set to 0.31 mass %, and the mixing ratio of purified water was set to 47.62 mass % relative to the entire inkjet ink. Except for this, the inkjet ink of Comparative Example 2 was obtained in the same manner as in Example 1.

[0276] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 2 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 1.3.

[0277] <Comparative Example 3>

[0278] In this comparative example, the inkjet ink of Comparative Example 3 was obtained in the same manner as in Example 1 except that the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 67.00 mass %, and the mixing ratio of ethanol was 25.00 mass %.

[0279] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 3 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0280] <Comparative Example 4>

[0281] In this comparative example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 27.00 mass %, and the mixing ratio of ethanol was set to 65.00 mass %, relative to the entire inkjet ink. Except for this, the inkjet ink of Comparative Example 4 was obtained in the same manner as in Example 1.

[0282] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 4 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0283] <Comparative Example 5>

[0284] In this comparative example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, purified water was 52.09 mass %, ethanol was 40.00 mass %, and PG was 0.01 mass %. Inkjet ink of Comparative Example 5 was obtained in the same manner as in Example 1 except for the above.

[0285] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 5 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0286] <Comparative Example 6>

[0287] In this comparative example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 37.10 mass %, and the mixing ratio of PG was set to 15.00 mass %, relative to the entire inkjet ink. Inkjet ink of Comparative Example 6 was obtained in the same manner as in Example 1 except for the above.

[0288] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 6 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 4.8.

[0289] <Comparative Example 7>

[0290] In this comparative example, the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 52.00 mass %, and the mixing ratio of cellobiose instead of reduced isomaltulose was 6.35 mass %. Inkjet ink of Comparative Example 7 was obtained in the same manner as in Example 1 except for the above.

[0291] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 7 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 0.0.

[0292] <Comparative Example 8>

[0293] In this comparative example, the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 52.00 mass %, and the mixing ratio of galactose instead of reduced isomaltulose was 6.35 mass %. Inkjet ink of Comparative Example 8 was obtained in the same manner as in Example 1 except for the above.

[0294] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 8 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 0.0.

[0295] <Comparative Example 9>

[0296] In this comparative example, the mixing ratio of Red No. 102 was 1.31 mass %, the mixing ratio of Red No. 3 was 0.08 mass %, the mixing ratio of Yellow No. 4 was 0.08 mass %, the mixing ratio of Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 54.35 mass %, and the mixing ratio of gum arabic instead of reduced isomaltulose was 4.00 mass %, relative to the entire inkjet ink. Except for this, the inkjet ink of Comparative Example 9 was obtained in the same manner as in Example 1.

[0297] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 9 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 0.0.

[0298] <Comparative Example 10>

[0299] In this comparative example, the mixing ratio of Red No. 102 was set to 1.31 mass %, the mixing ratio of Red No. 3 was set to 0.08 mass %, the mixing ratio of Yellow No. 4 was set to 0.08 mass %, the mixing ratio of Blue No. 1 was set to 0.08 mass %, the mixing ratio of purified water was set to 57.85 mass %, and the mixing ratio of sodium alginate instead of reduced isomaltulose was set to 0.50 mass %. Inkjet ink of Comparative Example 10 was obtained in the same manner as in Example 1 except for the above.

[0300] Thus, the mass ratio of reduced isomaltulose to Red No. 102 in the inkjet ink of Comparative Example 10 (mass of reduced isomaltulose / mass of Red No. 102) was adjusted to 0.0.

[0301] <Comparative Example 11>

[0302] In this comparative example, the mixing ratio of Red No. 102 was 1.31 mass %, Red No. 3 was 0.08 mass %, Yellow No. 4 was 0.08 mass %, Blue No. 1 was 0.08 mass %, the mixing ratio of purified water was 57.85 mass %, and the mixing ratio of hydroxypropyl methylcellulose instead of reduced isomaltulose was 0.50 mass %, relative to the entire inkjet ink. Inkjet ink of Comparative Example 11 was obtained in the same manner as in Example 1 except for the above.

[0303] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Comparative Example 11 was adjusted to 0.0.

[0304] <Comparative Example 12>

[0305] In this comparative example, the mixing ratio of Red No. 102 was 6.00 mass %, the mixing ratio of Red No. 3 was 0.37 mass %, the mixing ratio of Yellow No. 4 was 0.37 mass %, the mixing ratio of Blue No. 1 was 0.37 mass %, the mixing ratio of purified water was 68.39 mass %, the mixing ratio of polyethylene glycol instead of PG was 7.50 mass %, the mixing ratio of polyglycerol fatty acid esters instead of PG was 2.00 mass %, and the mixing ratio of reduced isomaltulose was 15.00 mass %. Except for this, the inkjet ink of Comparative Example 12 was obtained in the same manner as in Example 1. It should be noted that in this comparative example, ethanol was not added.

[0306] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Comparative Example 12 was adjusted to 2.5.

[0307] <Comparative Example 13>

[0308] In this comparative example, the mixing ratio of Red No. 102 was set to 0.30 mass % and the mixing ratio of purified water was set to 53.25 mass % relative to the entire inkjet ink. Inkjet ink of Comparative Example 13 was obtained in the same manner as in Example 1. It should be noted that in this comparative example, no color material other than Red No. 102 was added.

[0309] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Comparative Example 13 was adjusted to 21.2.

[0310] <Comparative Example 14>

[0311] In this comparative example, the mixing ratio of Red No. 102 was set to 5.00 mass % and the mixing ratio of purified water was set to 48.55 mass % relative to the total inkjet ink. Inkjet ink of Comparative Example 14 was obtained in the same manner as in Example 1. It should be noted that in this comparative example, no color material other than Red No. 102 was added.

[0312] Thus, the mass ratio of reduced isomaltulose to Red No. 102 (mass of reduced isomaltulose / mass of Red No. 102) in the inkjet ink of Comparative Example 14 was adjusted to 1.3.

[0313] The inks of Examples 1 to 46 and Comparative Examples 1 to 14 were passed through membrane filters to remove solid foreign matter in the liquid. Specifically, the inks were passed through a membrane filter (cellulose acetate membrane) with a pore size of 5.0 μm once and then through a membrane filter (cellulose acetate membrane) with a pore size of 0.8 μm once to obtain purified inks.

[0314] <Evaluation>

[0315] For the inks of the above-mentioned embodiments and comparative examples, solubility, viscosity, readability, initial ejection, fine line reproducibility, intermittent recovery, tablet drying, and light resistance were evaluated by the following methods. The evaluation results are shown in Tables 1 to 4. It should be noted that the "blank" part in Tables 1 to 4 indicates that the substance is not used. In addition, in Comparative Example 10, the sodium alginate used as a viscosity modifier has low solubility relative to the solvent used in Comparative Example 10. Therefore, the viscosity, readability, initial ejection, fine line reproducibility, intermittent recovery, tablet drying, and light resistance of the ink of Comparative Example 10 cannot be evaluated, and are marked with "-" in Table 4.

[0316] (Solubility test)

[0317] After adding the pigment (color material) and various additives to the solvent, the mixture was stirred at room temperature and humidity for 1 hour. The samples in which the pigment and other solutes were dissolved were stored at low temperature (below 5°C) for 1 week, and their solubility was verified.

[0318] ○: The solute is completely dissolved after stirring for 1 hour at room temperature and humidity, and no precipitate is produced when stored at low temperature (below 5°C)

[0319] △: The solute is completely dissolved after stirring for 1 hour at room temperature and humidity, and there is precipitation when stored at low temperature (below 5°C)

[0320] ×: Even after stirring for 1 hour at room temperature and humidity, some of the water remains insoluble

[0321] In addition, if the evaluation of the solubility test was "○" or "△", there was no problem in use, and it was regarded as passing.

[0322] (Viscosity measurement)

[0323] The viscosity of the ink of each example and each comparative example was measured using a rotational viscometer under the measurement condition of a measurement temperature of 25°C.

[0324] ◎:2.5mPa·s≤Viscosity≤3.5mPa·s

[0325] ○: 2.0mPa·s≤Viscosity<2.5mPa·s

[0326] ○: 3.5mPa·s<Viscosity≤5.0mPa·s

[0327] △: 5.0mPa·s<Viscosity≤6.0mPa·s

[0328] △-: 1.0mPa·s≤Viscosity<2.0mPa·s

[0329] △-: 6.0mPa·s<Viscosity≤7.0mPa·s

[0330] ×: Viscosity <1.0 mPa·s

[0331] ×: 7.0 mPa·s<viscosity

[0332] In addition, when the evaluation of viscosity was "◎", "○", "△", or "△-", there was no problem in use, and it was determined to be acceptable.

[0333] (readability)

[0334] Readability was evaluated based on optical density (OD value). The evaluation criteria for readability are as follows.

[0335] ◎:0.3 <OD

[0336] 0:0.2 <OD≤0.3

[0337] △: 0.15 <OD≤0.2

[0338] ×: OD≤0.15

[0339] In addition, if the evaluation of readability is "◎", "○", or "△", there is no problem in use, and it is determined to be acceptable.

[0340] (Initial ejection)

[0341] The inkjet head used was a piezoelectric ceramic-driven on-demand inkjet head with a printing resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (the conveying direction of recording media such as tablets), and a total number of nozzles of 1,280. Using the above inkjet head, a test pattern was printed immediately after the nozzle maintenance was implemented. Then, based on the printing status of the test pattern, the readability of the printed image generated with the ejection failure area was confirmed. The evaluation criteria are as follows.

[0342] ◎: No ejection failure

[0343] ○: Readable

[0344] ×: No readability

[0345] In addition, if the evaluation of the initial discharge property was "◎" or "○", there was no problem in use, and it was determined to be acceptable.

[0346] (Thin line reproducibility)

[0347] The inkjet head used was a piezoelectric ceramic-driven on-demand inkjet head with a printing resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (the conveying direction of the recording medium such as tablets), and a total number of nozzles of 1,280. Using the above inkjet head, a test pattern was printed immediately after the nozzle maintenance was implemented. Then, the reproducibility of the printed image of a 1-dot fine line was confirmed based on the printing condition of the test pattern. The evaluation criteria are as follows.

[0348] ○: Reproduced according to the printed image

[0349] △: Partial position deviation from the printed image

[0350] ×: Positional deviation occurs from the entire printed image

[0351] In addition, if the evaluation of thin line reproducibility is "○" or "△", there is no problem in use, and it is considered to be acceptable.

[0352] (Intermittent recovery (discharge stability) test)

[0353] A piezoelectric ceramic-driven on-demand inkjet head with a printing resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (the conveying direction of recording media such as tablets), and a total number of nozzles of 1,280 was used. The ink was placed for a specified time (15 minutes to 60 minutes) without flushing, and then a test pattern was printed with a droplet of 6 pl to confirm that it can be ejected from all nozzles without ejection failure. It should be noted that in the following Tables 1 to 4, as the evaluation results of intermittent printing (intermittent recovery / ejection stability), the standing time that allows ink ejection was measured. The evaluation criteria are as follows.

[0354] ◎: 30 minutes or more and less than 60 minutes

[0355] 0:15 minutes or more and less than 30 minutes

[0356] △: 5 minutes or more and less than 15 minutes

[0357] ×: Less than 5 minutes

[0358] In addition, if the evaluation of the intermittent recovery property (discharge stability) test was "◎", "○", or "△", there was no problem in use, and it was determined to be acceptable.

[0359] (Tablet Drying (Transfer Resistance) Test)

[0360] Using a piezoelectric ceramic-driven on-demand inkjet head with a printing resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (the conveying direction of recording media such as tablets), and a total number of nozzles of 1,280, images were printed on the following tablets using the inkjet inks of the embodiments and comparative examples with a printing drop amount of 10 pl per drop.

[0361] After 10 seconds of printing, a white carbon paper attached to a digital force gauge was brought into contact with the printed tablet for 0.4 to 0.5 seconds under a pressure of 4 to 5 N to confirm that the printed ink was not transferred. It should be noted that in Tables 1 to 4, as the evaluation results of transfer resistance (drying property), the concentration of the transferred ink was visually observed. The evaluation criteria are as follows.

[0362] ◎: No ink transfer

[0363] ○: The ink transfer is very small and difficult to confirm visually

[0364] ×: The ink color is transferred very darkly

[0365] In addition, when the evaluation of tablet drying property (transfer resistance) was "◎" or "○", there was no problem in use, and it was regarded as passing.

[0366] (Lightfastness test)

[0367] The purified inks of Examples 1 to 46 and Comparative Examples 1 to 14 were used to print images on the following tablets at a drop amount of 6 pl per drop using a piezoelectric ceramic driven on-demand inkjet head with a printing resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (the conveying direction of the recording medium such as the tablet), and a total number of nozzles of 1,280. It should be noted that the purified inks of Examples 1 to 46 and Comparative Examples 1 to 14 were used (printed) under a normal humidity environment (60% RH) and the light resistance test was performed under a normal humidity environment (50% RH).

[0368] The tablet to be printed was a test film-coated tablet (base: adjusted starch, coating agent: 70% hydroxypropyl methylcellulose / 30% titanium oxide mixture, diameter: 6.5 mm). In addition, the printed image was a circular solid image (diameter 4.0 mm). Thus, a film-coated tablet print was obtained.

[0369] The printed film-coated tablets of each embodiment and each comparative example, whose chromaticity and optical color density were measured, were irradiated with a cumulative visible light of 1.2 million lux using a light stability tester (Nagano Science LT-120A-WD). The chromaticity and optical color density of the printed film-coated tablets irradiated with visible light were measured using a spectrophotometer, and the color difference ΔE (values ​​obtained according to JIS Z 8781) indicating the amount of change in chromaticity and optical color density before and after irradiation with visible light was compared. The results of the comparison are shown in Tables 1 to 4. As described above, regarding the change in color tone before and after irradiation with visible light, as described above, the inventors have deduced that if the color difference ΔE of JIS Z 8781 is 20 or less (ΔE≤20), photochromic fading is sufficiently suppressed, thereby having excellent light resistance. Therefore, if ΔE≤20, the inkjet ink has excellent light fastness and is considered to be acceptable in this evaluation, and if ΔE≤13, the inkjet ink has very excellent light fastness and is considered to be more excellent in this evaluation.

[0370] ◎: ΔE≤13

[0371] 0:13<ΔE≤15

[0372] △: 15<ΔE≤20

[0373] ×: 20<ΔE

[0374] In addition, if the evaluation of the light resistance test was "◎", "○", or "△", there was no problem in use, and it was regarded as passing.

[0375] [Table 1]

[0376]

[0377] [Table 2]

[0378]

[0379] [Table 3]

[0380]

[0381] [Table 4]

[0382]

[0383] As shown in Tables 1 to 4, it can be seen that the evaluation results of the intermittent recovery of the inkjet inks of Examples 1 to 46 were all "△" or higher, indicating that the inkjet inks had sufficient intermittent recovery.

[0384] Furthermore, as shown in Tables 1 to 4, it can be seen that the evaluation results of the tablet drying properties of the inkjet inks of Examples 1 to 46 were all “◯” or higher, indicating that the tablet drying properties were sufficient.

[0385] Furthermore, as shown in Tables 1 to 4, it can be seen that the inkjet inks of Examples 1 to 46 all had light resistance evaluation results of “△” or higher, indicating that they had sufficient light resistance.

[0386] As described above, if the inkjet ink contains Red No. 102, reduced isomaltulose, water as a solvent, a monohydric alcohol and a wetting agent, the monohydric alcohol contains at least one of ethanol, NPA and IPA, the wetting agent contains at least one of glycerol and PG, the mixing ratio of Red No. 102 is in the range of 0.5 mass% to 3.0 mass% with respect to the mass of the entire inkjet ink, the mixing ratio of the monohydric alcohol is in the range of 30 mass% to 60 mass% with respect to the mass of the entire inkjet ink, and the mixing ratio of the wetting agent is in the range of 0.05 mass% to 10 mass% with respect to the mass of the entire inkjet ink, it is possible to provide an inkjet ink having drying property (tablet drying property), light resistance and ejection stability (intermittent recovery property), and a tablet printed product having a printed portion obtained by printing using the inkjet ink.

[0387] In addition, for example, the present invention can adopt the following configurations. (1)

[0389] An inkjet ink, characterized in that

[0390] Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent.

[0391] The monohydric alcohol contains at least one of ethanol, NPA and IPA,

[0392] The wetting agent contains at least one of glycerin and PG,

[0393] The mixing ratio of the red No. 102 is in the range of 0.5 mass % to 3.0 mass % relative to the total mass of the inkjet ink.

[0394] The mixing ratio of the monohydric alcohol is in the range of 30% by mass or more and 60% by mass or less relative to the total mass of the inkjet ink.

[0395] The mixing ratio of the wetting agent is in the range of 0.05 mass % to 10 mass % based on the total mass of the inkjet ink. (2)

[0397] The inkjet ink according to (1) above, wherein the amount of the reduced isomaltulose blended is in a range of 3.0% by mass to 8.5% by mass based on the total mass of the inkjet ink. (3)

[0399] An inkjet ink, characterized in that

[0400] Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent.

[0401] The monohydric alcohol contains at least one of ethanol, NPA and IPA,

[0402] The wetting agent contains at least one of glycerin and PG,

[0403] The mixing ratio of the red No. 102 is within a range of 1% by mass or more and 2.5% by mass or less relative to the total mass of the inkjet ink.

[0404] The mixing ratio of the monohydric alcohol is in the range of 35 mass % to 55 mass % based on the total mass of the inkjet ink.

[0405] The mixing ratio of the wetting agent is in the range of 0.05 mass % to 6 mass % based on the total mass of the inkjet ink.

[0406] The amount of the reduced isomaltulose blended is within a range of 4% by mass or more and 8% by mass or less relative to the total mass of the inkjet ink. (4)

[0408] An inkjet ink, characterized in that

[0409] Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent.

[0410] The monohydric alcohol contains at least one of ethanol, NPA and IPA,

[0411] The wetting agent contains at least one of glycerin and PG,

[0412] The mixing ratio of the red No. 102 is within a range of 1% by mass to 1.6% by mass relative to the total mass of the inkjet ink.

[0413] The mixing ratio of the monohydric alcohol is in the range of 35 mass % to 50 mass % based on the total mass of the inkjet ink.

[0414] The mixing ratio of the wetting agent is in the range of 0.05 mass % to 4 mass % based on the total mass of the inkjet ink.

[0415] The amount of the reduced isomaltulose blended is within a range of 5% by mass or more and 8% by mass or less relative to the total mass of the inkjet ink. (5)

[0417] The inkjet ink according to any one of (1) to (4) above is characterized in that the viscosity of the inkjet ink is in the range of 1.0 mPa·s to 7.0 mPa·s. (6)

[0419] The inkjet ink according to any one of (1) to (4) above, wherein the viscosity of the inkjet ink is within a range of 2.0 mPa·s to 6.0 mPa·s. (7)

[0421] The inkjet ink according to any one of (1) to (4) above is characterized in that the viscosity of the inkjet ink is in the range of 2.0 mPa·s to 5.0 mPa·s. (8)

[0423] An inkjet ink, characterized in that

[0424] Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent.

[0425] The monohydric alcohol contains at least one of ethanol, NPA and IPA,

[0426] The wetting agent contains at least one of glycerin and PG,

[0427] The mixing ratio of the red No. 102 is within a range of 1 mass % to 1.31 mass % relative to the total mass of the inkjet ink.

[0428] The mixing ratio of the monohydric alcohol is in the range of 30 mass % to 50 mass % based on the total mass of the inkjet ink.

[0429] The mixing ratio of the wetting agent is in the range of 0.05 mass % to 4 mass % based on the total mass of the inkjet ink.

[0430] The amount of the reduced isomaltulose blended is within a range of 4% by mass or more and 8% by mass or less relative to the total mass of the inkjet ink. (9)

[0432] The inkjet ink according to any one of (1) to (8) above, wherein the monohydric alcohol contains only the ethanol, only the NPA, or only the IPA,

[0433] As the moisturizing agent, only the glycerin or only the PG is contained. (10)

[0435] A tablet printed article comprising a printed portion obtained by printing using the inkjet ink described in any one of (1) to (9) above.

[0436] The scope of the present invention is not limited to the exemplary embodiments described in the drawings, but includes all embodiments having equal effects with the purpose of the present invention. In addition, the scope of the present invention is not limited to the feature combination of the invention defined by the claims, but can be defined by all desired combinations of specific features among all disclosed features.

Claims

1. An inkjet ink, characterized in that: Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent. The monohydric alcohol contains at least one of ethanol, NPA and IPA, The wetting agent contains at least one of glycerin and PG, The mixing ratio of the red No. 102 is in the range of 0.5 mass % to 3.0 mass % relative to the total mass of the inkjet ink. The mixing ratio of the monohydric alcohol is in the range of 30 mass % to 60 mass % based on the total mass of the inkjet ink. The mixing ratio of the wetting agent is in the range of 0.05 mass % to 10 mass % based on the total mass of the inkjet ink.

2. The inkjet ink according to claim 1, characterized in that The amount of the reduced isomaltulose blended is within a range of 3.0% by mass to 8.5% by mass based on the total mass of the inkjet ink.

3. An inkjet ink, characterized in that: Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent. The monohydric alcohol contains at least one of ethanol, NPA and IPA, The wetting agent contains at least one of glycerin and PG, The mixing ratio of the red No. 102 is within a range of 1% by mass or more and 2.5% by mass or less relative to the total mass of the inkjet ink. The mixing ratio of the monohydric alcohol is in the range of 35 mass % to 55 mass % based on the total mass of the inkjet ink. The mixing ratio of the wetting agent is in the range of 0.05 mass % to 6 mass % based on the total mass of the inkjet ink. The amount of the reduced isomaltulose blended is within a range of 4% by mass or more and 8% by mass or less relative to the total mass of the inkjet ink.

4. An inkjet ink, characterized in that Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent. The monohydric alcohol contains at least one of ethanol, NPA and IPA, The wetting agent contains at least one of glycerin and PG, The mixing ratio of the red No. 102 is within a range of 1% by mass to 1.6% by mass relative to the total mass of the inkjet ink. The mixing ratio of the monohydric alcohol is in the range of 35 mass % to 50 mass % based on the total mass of the inkjet ink. The mixing ratio of the wetting agent is in the range of 0.05 mass % to 4 mass % based on the total mass of the inkjet ink. The amount of the reduced isomaltulose blended is within a range of 5% by mass or more and 8% by mass or less relative to the total mass of the inkjet ink.

5. The inkjet ink according to claim 2, characterized in that The viscosity of the inkjet ink is in the range of 1.0 mPa·s to 7.0 mPa·s.

6. The inkjet ink according to claim 2, characterized in that The viscosity of the inkjet ink is in the range of 2.0 mPa·s to 6.0 mPa·s.

7. The inkjet ink according to claim 2, characterized in that The viscosity of the inkjet ink is in the range of 2.0 mPa·s to 5.0 mPa·s.

8. An inkjet ink, characterized in that Contains Red No. 102, reduced isomaltulose, water as a solvent, monohydric alcohol, and a wetting agent. The monohydric alcohol contains at least one of ethanol, NPA and IPA, The wetting agent contains at least one of glycerin and PG, The mixing ratio of the red No. 102 is within a range of 1 mass % to 1.31 mass % relative to the total mass of the inkjet ink. The mixing ratio of the monohydric alcohol is in the range of 30 mass % to 50 mass % based on the total mass of the inkjet ink. The mixing ratio of the wetting agent is in the range of 0.05 mass % to 4 mass % based on the total mass of the inkjet ink. The amount of the reduced isomaltulose blended is within a range of 4% by mass or more and 8% by mass or less relative to the total mass of the inkjet ink.

9. The inkjet ink according to any one of claims 1 to 8, characterized in that: As the monohydric alcohol, only the ethanol, only the NPA, or only the IPA is contained, As the moisturizing agent, only the glycerin or only the PG is contained. 10 . A tablet printed article, comprising a printed portion obtained by printing using the inkjet ink according to claim 1 .

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