Inkjet ink and tablet printed matter

Abstract

The purpose of the present invention is to provide: an inkjet ink which sufficiently suppresses photochromic fading of a printed image and which has excellent light resistance; and a tablet printed matter which is provided with a printed section printed by means of the inkjet ink. When the inkjet ink according to the present embodiment contains blue No.1 as an edible dye, contains water and ethanol as solvents, and only contains trehalose as a fixing agent, the blending ratio of the trehalose is 7.5 mass% or more and 20.0 mass% or less with respect to the mass of the entire inkjet ink. When trehalose and reduced isomaltulose are contained as fixing agents, the blending proportion of the trehalose is in the range of 2.5 mass% to 15.0 mass% (inclusive) with respect to the mass of the entire inkjet ink, and the blending proportion of the reduced isomaltulose is 10.0 mass% or less with respect to the mass of the entire inkjet ink.

Description

Technical Field

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

[0002] Inkjet printing inks (hereinafter also simply referred to as "inkjet inks") sometimes have edibility, for example, by using food dyes such as tar-based pigments as color materials.

[0003] Conventionally, in inkjet inks, due to the deterioration of color materials, discoloration in which the color (hue) of the color material changes and fading caused by a decrease in the chroma of the color material may occur in printed characters and images. For example, when the light resistance of an inkjet ink is insufficient, the color material decomposes (photodecomposes) due to the action of light, and thus discoloration and fading (photochromic fading) may occur. Such discoloration and fading are recognized as a decrease in the visibility of 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 underway, and various methods for suppressing discoloration and fading have been proposed (for example, Patent Document 1). However, in the conventional methods, the photochromic fading of printed images cannot be sufficiently suppressed, and thus the light resistance of inkjet inks cannot be improved.

[0005] For example, for Food Blue No. 1 among food dyes, the light resistance of an inkjet ink is sometimes improved by containing isomaltulose in the inkjet ink.

[0006] Isomaltulose is a substance classified as a disaccharide, but when compared among the same disaccharides, isomaltulose has a relatively low solubility in water.

[0007] Therefore, it is sometimes difficult to sufficiently increase the addition ratio (upper limit of the content rate) of isomaltulose in an inkjet ink.

[0008] Prior Art Documents

[0009] Patent Documents

[0010] Patent Document 1: Japanese Patent No. 6389506 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] The present inventors have found that in order to further improve the light resistance of an inkjet ink, it is necessary to add a light resistance inhibitor having higher solubility to the inkjet ink.

[0013] The present invention has been completed in view of this point, and an object thereof is to provide an inkjet ink in which photochromic fading of a printed image is sufficiently suppressed and light resistance is improved, and a tablet printed matter having a printed portion printed with the inkjet ink.

[0014] Means for Solving the Problems

[0015] In order to achieve the above object, an inkjet ink according to one embodiment of the present invention is characterized in that it contains Brilliant Blue FCF as a food dye, contains only trehalose as a fixing agent, contains water and ethanol as solvents, and the blending ratio of the trehalose is in the range of 7.5% by mass or more and 20.0% by mass or less with respect to the total mass of the inkjet ink.

[0016] In addition, in order to achieve the above object, an inkjet ink according to one embodiment of the present invention is characterized in that it contains Brilliant Blue FCF as a food dye, contains trehalose and isomaltulose as fixing agents, contains water and ethanol as solvents, the blending ratio of the trehalose is in the range of 2.5% by mass or more and 15.0% by mass or less with respect to the total mass of the inkjet ink, and the blending ratio of the isomaltulose is 10.0% by mass or less with respect to the total mass of the inkjet ink.

[0017] In addition, in order to achieve the above object, a tablet printed matter according to one embodiment of the present invention is characterized in that it has a printed portion printed with the above inkjet ink.

[0018] Effects of the Invention

[0019] According to one embodiment of the present invention, photochromic fading of a printed image can be sufficiently suppressed, and the light resistance of the inkjet ink can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] [FIG. 1] is a schematic diagram for explaining the permeability and light resistance of the inkjet ink according to the embodiment of the present invention.

[0021] Figure 2 is a schematic cross-sectional view showing an example of a tablet (plain tablet) according to the embodiment of the present invention.

[0022] Figure 3 is a schematic cross-sectional view showing an example of a tablet (film-coated tablet) according to the embodiment of the present invention.

[0023] Figure 4 is an example of a printed image of a tablet (plain tablet) according to the embodiment of the present invention.

[0024] Figure 5 is an example of a printed image of a tablet (film-coated tablet) according to the embodiment of the present invention. ​​​​

[0025] Explanation of Symbols

[0026] 1 Substrate of tablet

[0027] 1S Surface

[0028] 3 Printed image

[0029] 4 Specific dye

[0030] 5 Plain tablet print

[0031] 7 Film coating layer

[0032] 9 Film-coated tablet print

[0033] 11 Plain tablet printed image (solid image)

[0034] 13 Film-coated tablet printed image (2D barcode) Detailed Description of the Invention

[0035] The inkjet ink according to an embodiment of the present invention (hereinafter referred to as "the present embodiment") relates to an inkjet ink that can sufficiently suppress photochromic fading of printed images and the like applied to the surface of medical tablets by an inkjet printing method and improve light resistance. Hereinafter, the inkjet ink according to the embodiment of the present invention and the configuration of a tablet having a printed portion printed with the inkjet ink will be described in detail.

[0036] 〔Configuration of Inkjet Ink〕

[0037] The inkjet ink according to the present embodiment is an edible inkjet ink and contains Food Blue No. 1 (hereinafter simply referred to as "Blue No. 1") as an edible dye (edible pigment). In addition, the inkjet ink according to the present embodiment contains a saccharide having a relatively high solubility in water as a fixing agent for fixing the ink to the surface of the printed material (e.g., solid preparation). Specifically, in the present embodiment, trehalose (a disaccharide) having a solubility of 69 g in 100 ml of water at 20°C is used as the fixing agent. In addition, the inkjet ink according to the present embodiment contains trehalose in the range of 7.5% by mass or more and 20.0% by mass or less based on the total mass of the inkjet ink. In addition, the inkjet ink according to the present embodiment contains water and ethanol as solvents.

[0038] In addition, in the present embodiment, trehalose and reduced isomaltulose (a disaccharide) with a solubility of 38 g in 100 ml of water at 20°C are used as fixing agents. In addition, the inkjet ink according to the present embodiment contains trehalose in the range of 2.5% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink. In addition, the inkjet ink according to the present embodiment contains reduced isomaltulose in the range of 10.0% by mass or less relative to the total mass of the inkjet ink. In addition, the inkjet ink according to the present embodiment contains water and ethanol as solvents.

[0039] According to such a configuration, photochromic fading of the printed image can be sufficiently suppressed, and the light resistance of the inkjet ink can be improved.

[0040] Hereinafter, this will be described with reference to FIG. 1.

[0041] FIG. 1 is a schematic diagram for explaining the relationship between the fixing of the ink on the surface of the printed matter (solid preparation) and the light resistance. Here, as the solid preparation, for example, a tablet having few voids and having a film coating portion, that is, a film-coated tablet is used. It should be noted that the present invention is not limited thereto, and a plain tablet or a capsule tablet may be used as the printed matter.

[0042] FIGS. 1(a) to 1(c) are schematic cross-sectional views in the thickness direction of the tablet in a state after a certain period of time when inkjet inks A to C having different compositions are printed on the tablet (here, a film-coated tablet). In this example, inkjet ink A is an ink using a specific dye 4 as a coloring material and water as a solvent. Here, the specific dye 4 only needs to contain Blue No. 1. In addition, inkjet ink B is an ink obtained by adding a predetermined saccharide to inkjet ink A. Here, the saccharide added to inkjet ink B is a saccharide having a relatively low solubility in water and not corresponding to the fixing agent of the present embodiment (for example, reduced isomaltulose). In addition, inkjet ink C is an ink obtained by adding a disaccharide having a relatively high solubility in water and corresponding to the fixing agent of the present embodiment (that is, trehalose) to inkjet ink A and further adding ethanol as a solvent to water.

[0043] Specifically, FIG. 1(a) is a schematic cross-sectional view in the thickness direction of the tablet in a state after a certain period of time (for example, 140 hours) when inkjet ink A containing a specific dye 4 as a coloring material and water as a solvent is printed on the surface 1S of the substrate 1 of the tablet. In addition, FIG. 1(b) is a schematic cross-sectional view in the thickness direction of the tablet in a state after a certain period of time (for example, 140 hours) when inkjet ink B is printed on the surface 1S of the substrate 1 of the tablet. In addition, FIG. 1(c) is a schematic cross-sectional view in the thickness direction of the tablet in a state after a certain period of time (for example, 140 hours) when inkjet ink C is printed on the surface 1S of the substrate 1 of the tablet.

[0044] First, regarding the permeability of sugars and dyes in inkjet inks, Inkjet Inks A and B will be taken as examples for illustration.

[0045] Among the various color materials used in inkjet inks, for example, in tar-based pigments used as food dyes, color fading may occur in characters, images, etc. printed on the surface of solid preparations. For example, No. 1 Blue among tar-based pigments penetrates into solid preparations over time or causes color fading of printed images due to photolysis. In response, the following methods are known: by adding sugars to inkjet inks, the penetration of dyes into solid preparations is suppressed, thereby suppressing color fading of printed images.

[0046] As shown in Fig. 1(a), when printing Inkjet Ink A without sugars, when a certain time has elapsed since the start of printing, a specific dye 4 penetrates into the interior of the substrate 1 of the tablet. Here, the penetration depth of the specific dye 4 in Inkjet Ink A after this certain time is set as the penetration depth X (μm). In contrast, as shown in Fig. 1(b), when printing Inkjet Ink B containing sugars, after a certain time has elapsed since the start of printing, the penetration depth Y (μm) of Inkjet Ink B is less than the penetration depth X of Inkjet Ink A (X > Y).

[0047] In Inkjet Ink B, due to the addition of a predetermined sugar, an increase in ink viscosity, etc., the penetration of the specific dye 4 into the interior of the substrate 1 of the tablet is suppressed. Therefore, when printing Inkjet Ink B, even after a certain time has elapsed since the start of printing, in the substrate 1 of the tablet, the specific dye 4 remains near the surface 1S. That is, compared with the case where no sugar is added, an inkjet ink containing a predetermined sugar can suppress color fading of printed images caused by the penetration of dyes (such as No. 1 Blue). On the other hand, in Inkjet Ink B to which a predetermined sugar is added, color fading of printed images caused by light irradiation (photochromic fading) cannot be sufficiently suppressed.

[0048] In contrast, the inkjet ink according to the present embodiment selects the types and physical properties of the added sugar and solvent, so that the ink adheres to the surface of the printed material, thereby sufficiently suppressing photochromic fading of printed images and improving light resistance. The present inventors have found that in order to suppress photochromic fading of printed images, it is effective to make the ink adhere to the surface of the printed material (such as a tablet). In this example, by adhering the ink to the surface 1S of the tablet, the specific dye 4 adheres to the surface 1S, and as a result, the specific dye 4 can remain on the surface 1S at a high concentration.

[0049] When the concentration of the specific dye 4 is high on the surface 1S of the base material 1 of the tablet, for example, the proportion of the colorant that undergoes photochromic fading due to photolysis among the specific dyes 4 on the surface 1S decreases. That is, even if a part of the specific dye 4 undergoes photochromic fading, the influence is limited, thereby suppressing the reduction in the visibility (readability) of the printed image. Thus, 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. And the present inventors have found that disaccharides among saccharides can also function as a fixing agent for fixing the ink containing Blue No. 1 as a colorant on the surface of the printed material. In addition, the present inventors have found that regarding the above-mentioned disaccharides used as a fixing agent, by using a substance with a relatively high solubility in the solvent, the addition amount of the disaccharides in the inkjet ink can be increased, thereby reliably exerting the fixing effect of the ink.

[0050] Specifically, the inkjet ink according to the present embodiment contains Blue No. 1 as a colorant, i.e., a food dye, contains only trehalose as a fixing agent, and contains water and ethanol as solvents. In addition, the mixing ratio of trehalose is in the range of 7.5% by mass or more and 20.0% by mass or less with respect to the total mass of the inkjet ink.

[0051] In addition, the inkjet ink according to the present embodiment contains Blue No. 1 as a colorant, i.e., a food dye, contains trehalose and reduced isomaltulose as fixing agents, and contains water and ethanol as solvents. In addition, the mixing ratio of trehalose is in the range of 2.5% by mass or more and 15.0% by mass or less with respect to the total mass of the inkjet ink, and the mixing ratio of reduced isomaltulose is 10.0% by mass or less with respect to the total mass of the inkjet ink.

[0052] According to such a configuration, the ink containing a specific tar-based pigment (Blue No. 1 in this example) used as a colorant can be fixed on the surface of the printed material, so that the above-mentioned specific tar-based pigment remains on the surface at a high concentration. Thus, the inkjet ink according to the present embodiment can sufficiently suppress the photochromic fading of the printed image and improve the light resistance.

[0053] As shown in Fig. 1(c), when the inkjet ink C equivalent to the inkjet ink according to this embodiment is printed on the surface 1S of the substrate 1 of the tablet, the specific dye 4 (here, Blue No. 1) in the ink adheres to the surface 1S. Specifically, in the case of printing the inkjet ink C, compared with the penetration depth Y of the specific dye 4 in the inkjet ink B containing a predetermined saccharide, the penetration depth Z (μm) of the specific dye 4 after a certain time from the start of printing is further reduced (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 as described above, the reduction in the visibility of the printed image is suppressed. Thus, the photochromic fading of the printed image can be sufficiently suppressed, and the inkjet ink C can improve the light resistance.

[0054] On the other hand, although the inkjet ink B can cause the specific dye 4 to remain near the surface 1S inside the substrate 1 of the tablet, the suppression of the penetration of the specific dye 4 is insufficient, and the ink cannot adhere to 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 (enhanced).

[0055] In this way, by adding the above-mentioned disaccharides (only trehalose, or a mixture of trehalose and reduced isomaltulose) as a fixing agent to the inkjet ink according to this embodiment, and further setting the solvent to the above-mentioned composition (a mixed solvent of water and ethanol), the penetration of a specific tar-based pigment (Blue No. 1) into the printed matter can be significantly suppressed, and the ink can adhere to the surface of the printed matter. Thus, the inkjet ink according to this embodiment can suppress the photochromic fading of the printed image and improve the light resistance, and further can also suppress the discoloration and fading of the printed image caused by the penetration of the above-mentioned specific tar-based pigment into the printed matter.

[0056] In addition, as shown in Fig. 1(c), the inkjet ink C can be made to adhere to the surface 1S of the substrate 1 of the tablet in a slightly raised manner. Thus, for example, in the case of printing the inkjet ink C, it is recognized in a manner that the printing appears deeper on the surface 1S. Therefore, for example, compared with the inkjet inks A and B, the inkjet ink C can improve the visibility of the printed image during printing. That is, in the inkjet ink according to this embodiment, not only the reduction in visibility caused by the photochromic fading of the printed image is reduced, but also good visibility can be imparted to the printed image during printing.

[0057] Hereinafter, the details of the light resistance of the inkjet ink according to this embodiment will be described.

[0058] The inkjet ink according to this embodiment only needs to have a color difference ΔE based on JIS Z8781 of 25 or less before and after the lightfastness test. Here, the lightfastness test is, for example, the following test: for a printed image obtained by printing with the inkjet ink according to this embodiment, the color difference ΔE (value according to JIS Z8781) representing the change amount of chromaticity and optical color density before and after visible light irradiation is compared. Specifically, the color difference ΔE before and after irradiating the printed image with visible light of 1.2 million lux in cumulative amount is measured and the values are compared. The irradiation of visible light is performed, for example, using a light stability test device (Nagano Science LT-120A-WD). In addition, the printed image in the lightfastness test is, for example, an image obtained by solid printing on a tablet (for example, a film-coated tablet) as a printing object.

[0059] Sufficient lightfastness required for forming a printed image on a medical tablet or the like mostly means that in the lightfastness test of irradiating visible light of 1.2 million lux under normal humidity (60% RH in the test machine setting room), the color difference ΔE of the printed image before and after visible light irradiation is 25 or less. The determination criterion of taking the color difference ΔE of 25 or less as sufficient lightfastness is derived from the results of opinion tests implemented by the inventor in exchange with various medical-related personnel. When the color difference ΔE exceeds 25, the visibility (for example, the readability of printing) of the printed image starts to be recognized as reduced. That is, if the color difference ΔE before and after visible light irradiation is 25 or less, it can be considered that the inkjet ink sufficiently suppresses photochromic fading and has excellent lightfastness. It should be noted that although it is a number larger than the standard color difference ΔE of 3 to 6 for ordinary commercial printed matter, usually the tablets before and after exposure are not compared, and assuming that the printed image on the tablet surface fades naturally, this number can be obtained.

[0060] In the inkjet ink according to this embodiment, the reason for using a disaccharide (for example, trehalose with a solubility of 69 g in 100 ml of water at 20°C) having a relatively large solubility in 100 ml of water at 20°C as a fixing agent and using a solvent composed of the above components is that when only adding a sugar having a relatively small solubility in 100 ml of water at 20°C (for example, reduced isomaltulose with a solubility of 38 g in 100 ml of water at 20°C), or when the solvent is not set to be composed of the above components, a specific tar-based pigment, Blue No. 1, on the tablet surface cannot be sufficiently fixed on the surface of the printed matter, and when the above lightfastness test is performed on the solid printed image, the color difference ΔE exceeds 25. By adding a disaccharide having a relatively large solubility in water as a fixing agent and using a solvent that satisfies the above component composition to increase the solubility of the above disaccharide in the solvent, the color difference ΔE before and after the lightfastness test is lower than 25, and excellent lightfastness is imparted to the inkjet ink.

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

[0062] (Colorant)

[0063] As described above, the inkjet ink of the present embodiment contains at least Brilliant Blue FCF as a food dye. Brilliant Blue FCF is a food tar pigment and is also known as Brilliant Blue FCF.

[0064] When only trehalose is contained as a fixing agent in the inkjet ink according to the present embodiment, the mixing ratio of the food dye containing the above-mentioned specific tar pigment (Brilliant Blue FCF), that is, the total content of the food dye relative to the mass of the entire ink, is preferably in the range of 1.0% by mass or more and 15.0% by mass or less.

[0065] In addition, when trehalose and isomaltulose are contained as fixing agents in the inkjet ink according to the present embodiment, the mixing ratio of the food dye containing the above-mentioned specific tar pigment (Brilliant Blue FCF), that is, the total content of the food dye relative to the mass of the entire ink, is preferably in the range of 1.0% by mass or more and 15.0% by mass or less.

[0066] According to such a configuration, good visibility can be imparted to the printed image and high intermittent recovery can be imparted. In addition, if the total content of the food dye is within the above range, by adding the above fixing agent, the above-mentioned specific tar pigment can be reliably retained on the surface of the printed matter at a high concentration, thereby suppressing the photochromic fading of the printed image and improving the light resistance of the inkjet ink according to the present embodiment.

[0067] On the contrary, in the inkjet ink containing only trehalose as a fixing agent, when the total content of the above food dye is less than 1.0% by mass, the overall printing color becomes lighter and the visibility of the printed image tends to decrease. In addition, when the content exceeds 15.0% by mass, due to the poor dissolution stability of the colorant, the pigment in the ink precipitates or deposits in a solid form, resulting in clogging of the nozzles of the inkjet head during printing, and the so-called printing recovery (intermittent recovery) may decrease.

[0068] In addition, in the inkjet ink containing trehalose and isomaltulose as fixing agents, when the total content of the above food dye is less than 1.0% by mass, the overall printing color becomes lighter and the visibility of the printed image tends to decrease. In addition, when the content exceeds 15.0% by mass, due to the poor dissolution stability of the colorant, the pigment in the ink precipitates or deposits in a solid form, resulting in clogging of the nozzles of the inkjet head during printing, and the so-called printing recovery (intermittent recovery) may decrease.

[0069] It should be noted that the inkjet ink of this embodiment may also contain pigments (color materials) other than the above-mentioned specific tar-based pigment, i.e., Blue No. 1. The pigments other than Blue No. 1 only need to be edible and are not particularly limited. The pigments that can be added to the inkjet ink of this embodiment can be appropriately selected and added, for example, from the existing well-known synthetic food pigments and natural food pigments. In addition, when the inkjet ink according to this embodiment contains a color material other than the above-mentioned specific tar-based pigment as an edible dye, regarding the total content of the edible dye, when only trehalose is used as a fixing agent, it can be in the range of 1.0% by mass or more and 15.0% by mass or less, and when trehalose and reduced isomaltulose are used as fixing agents, it can be in the range of 1.0% by mass or more and 15.0% by mass or less. Thereby, the light resistance of the inkjet ink can be improved, good visibility can be imparted to the printed image, and sufficient intermittent recoverability can be imparted to the inkjet ink.

[0070] Examples of synthetic food pigments include tar-based pigments, natural pigment derivatives, natural-based synthetic pigments, etc. Examples of tar-based pigments include: Food Red No. 2, Food Red No. 3, Food Red No. 40, Food Red No. 102, Food Red No. 104, Food Red No. 105, Food Red No. 106, Food Yellow No. 4, Food Yellow No. 5, Food Blue No. 2, Food Red No. 2 Aluminum Lake, Food Red No. 3 Aluminum Lake, Food Red No. 40 Aluminum Lake, Food Yellow No. 4 Aluminum Lake, Food Yellow No. 5 Aluminum Lake, Food Blue No. 1 Aluminum Lake, Food Blue No. 2 Aluminum Lake, etc. Examples of natural pigment derivatives include norbixin kalium, etc. Examples of natural-based synthetic pigments include β-carotene, riboflavin, etc.

[0071] In addition, as natural food colorants, for example, anthocyanin pigments, carotenoid pigments, quinone pigments, chlorophyll pigments, flavonoid pigments, betaine pigments, Monascus pigments, and other pigments derived from natural substances can be cited. As anthocyanin pigments, for example, the following can be cited: carrot pigment, red cabbage pigment, red rice pigment, elderberry pigment, bilberry pigment, currant pigment, cranberry pigment, salmonberry pigment, perilla pigment, sim blueberry pigment, strawberry pigment, dark sweet cherry pigment, cherry pigment, hibiscus pigment, cranberry pigment, grape juice pigment, grape skin pigment, blackcurrant pigment, blackberry pigment, blueberry pigment, plum pigment, bilberry pigment, boysenberry pigment, mulberry pigment, purple sweet potato pigment, purple corn pigment, purple yam pigment, raspberry pigment, red currant pigment, loganberry pigment, and other anthocyanin pigments. As carotenoid pigments, for example, carminic acid pigment, gardenia yellow pigment, and other carotenoid pigments can be cited. As quinone pigments, for example, carmine pigment, purple gromwell root pigment, shellac pigment, and other quinone pigments can be cited. As flavonoid pigments, for example, safflower yellow pigment, sorghum pigment, onion pigment, and other flavonoid pigments can be cited. As betaine pigments, for example, betanin can be cited. As Monascus pigments, for example, Monascus pigment and Monascus yellow pigment can be cited. As other pigments derived from natural substances, for example, curcumin, clerodendrin pigment, gardenia red pigment, spirulina blue pigment, etc. can be cited.

[0072] (Fixing agent)

[0073] As described above, the inkjet ink according to the present embodiment contains a fixing agent for fixing the ink containing a specific tar-based pigment (Blue No. 1) on the surface of the printed material. Specifically, the fixing agent contained in the inkjet ink according to the present embodiment is trehalose. Trehalose is a disaccharide with a solubility of 69 g in 100 ml of water at 20°C. Since the solubility of trehalose in 100 ml of water at 20°C is higher than that of other disaccharides, the addition amount of trehalose can be increased relative to a water-containing solvent. Therefore, according to the inkjet ink having the above configuration, high light resistance (ΔE ≤ 25) can be achieved even under normal humidity.

[0074] In addition, in the inkjet ink according to this embodiment, trehalose and isomaltulose can also be used in combination as a fixing agent. Isomaltulose is a disaccharide with a solubility of 38 g in 100 ml of water at 20°C. In addition, the types of solvents in which trehalose and isomaltulose are each easily soluble are different. That is, in the inkjet ink according to this embodiment, the solubilities in water and ethanol used as solvents are different. Therefore, in this embodiment, by using trehalose and isomaltulose in combination as a fixing agent, compared with the case of using only trehalose as a fixing agent, the maximum dissolution amount (total dissolution amount) in a solvent containing water and ethanol can be increased. As a result, according to this configuration, high light resistance (ΔE ≤ 25) can be achieved even under normal humidity.

[0075] If the fixing agent has this configuration, by adding it to the inkjet ink together with the solvent having the above composition (water and ethanol), the ink containing the above specific tar-based pigment can be fixed on the surface of the printed material. Thus, the inkjet ink of this embodiment can sufficiently suppress the photochromic fading of the printed image and improve the light resistance. In addition, in this embodiment, the above disaccharide (only trehalose or a mixture of trehalose and isomaltulose) used as a fixing agent also has a function of suppressing the decomposition (photodegradation) of the inkjet ink caused by light irradiation. Therefore, the occurrence of photochromic fading itself can also be suppressed.

[0076] In the inkjet ink according to this embodiment, when only trehalose is contained as a fixing agent, the mixing ratio of trehalose relative to the total mass of the ink is preferably in the range of 7.5% by mass or more and 20.0% by mass or less, more preferably in the range of 7.5% by mass or more and 18.0% by mass or less, and further preferably in the range of 7.5% by mass or more and 16.0% by mass or less.

[0077] In addition, in the inkjet ink according to this embodiment, when trehalose and isomaltulose are contained as a fixing agent, the mixing ratio of trehalose relative to the total mass of the ink is preferably in the range of 2.5% by mass or more and 15.0% by mass or less, more preferably in the range of 5.0% by mass or more and 15.0% by mass or less, and more preferably in the range of 7.5% by mass or more and 15.0% by mass or less. In addition, the mixing ratio of isomaltulose relative to the total mass of the ink is preferably 10.0% by mass or less, more preferably in the range of 8.0% by mass or more and 10.0% by mass or less.

[0078] According to such a configuration, the ink fixing effect of the above disaccharide can be more reliably exhibited, and the light resistance of the inkjet ink can be reliably improved. In addition, high intermittent recoverability can be imparted to the inkjet ink according to this embodiment.

[0079] In contrast, when only trehalose is used as a fixing agent, if the mixing ratio of the fixing agent is less than 7.5% by mass, the fixing effect of the ink decreases, and it may be difficult to obtain light resistance. Additionally, when the mixing ratio of the fixing agent (trehalose) exceeds 20% by mass, due to the increase in ink viscosity and the poor dissolution stability of the fixing agent, the fixing agent in the ink precipitates or deposits in solid form, resulting in nozzle blockage of the inkjet head during printing, and thus the ejection stability may decrease.

[0080] In addition, when trehalose and reduced isomaltulose are used as fixing agents, if the mixing ratio of trehalose is less than 2.5% by mass, the fixing effect of the ink decreases, and it may be difficult to obtain light resistance. Additionally, when the mixing ratio of trehalose exceeds 15.0% by mass, due to the increase in ink viscosity and the poor dissolution stability of the fixing agent, the fixing agent in the ink precipitates or deposits in solid form, resulting in nozzle blockage of the inkjet head during printing, and thus the ejection stability may decrease.

[0081] In addition, when trehalose and reduced isomaltulose are used as fixing agents, if the mixing ratio of reduced isomaltulose exceeds 10.0% by mass, due to the increase in ink viscosity and the poor dissolution stability of the fixing agent, the fixing agent in the ink precipitates or deposits in solid form, resulting in nozzle blockage of the inkjet head during printing, and thus the ejection stability may decrease.

[0082] It should be noted that in the inkjet ink according to this embodiment, when trehalose and reduced isomaltulose are used as fixing agents, it is sufficient that the total mixing ratio of trehalose and reduced isomaltulose is 7.5% by mass or more.

[0083] According to such a configuration, the fixing effect of the inkjet ink according to this embodiment can be more reliably exerted, and the light resistance of the inkjet ink can be reliably improved.

[0084] In addition, the mixing ratio of trehalose can also be greater than that of reduced isomaltulose.

[0085] According to such a configuration, the ink fixing effect of the above-mentioned disaccharides can be more reliably exerted, and the light resistance of the inkjet ink can be reliably improved.

[0086] In addition, in the inkjet ink according to this embodiment, when trehalose and reduced isomaltulose are used as fixing agents, the mixing ratio of reduced isomaltulose can also be greater than that of trehalose.

[0087] According to such a configuration, the ink fixing effect of the above-mentioned disaccharides can be more reliably exerted, and the light resistance of the inkjet ink can be reliably improved.

[0088] (Solvent)

[0089] In addition to the above-mentioned specific coal-tar pigment (Blue No. 1) and the above-mentioned fixing agent, the inkjet ink according to the present embodiment further contains a solvent (dispersion medium) for dissolving (dispersing) the specific coal-tar pigment and the fixing agent. In the inkjet ink according to the present embodiment, as the solvent, it is sufficient to contain water (for example, purified water) and ethanol.

[0090] Generally, saccharides have the property of being hardly soluble in alcohols. Therefore, in the present embodiment, by containing ethanol in the solvent, the solubility of the above-mentioned disaccharide used as the fixing agent in the solvent is moderately reduced. Therefore, in the present embodiment, by adding the above-mentioned disaccharide (only trehalose, or a mixture of trehalose and reduced isomaltulose) used as the fixing agent and the solvent containing the above-mentioned alcohol (ethanol) to the inkjet ink, the fixing effect of the ink can be reliably exerted, and the above-mentioned specific coal-tar pigment (Blue No. 1 in this example) contained in the ink can remain on the surface of the printed matter (for example, a tablet) at a higher concentration. Thus, the inkjet ink of the present embodiment can sufficiently suppress the photochromic fading of the printed image and improve the light resistance.

[0091] In addition, the inkjet ink according to the present embodiment may further contain propylene glycol (PG) as a solvent. Propylene glycol functions as a wetting agent, can prevent the drying of the ink at the inkjet nozzle, and imparts sufficient intermittent recoverability to the ink. In addition, since ethanol has a high volatility, the transfer resistance (drying property) of the inkjet ink can be improved.

[0092] In addition, in the inkjet ink according to the present embodiment, the mixing ratio of each component of the above-mentioned solvent is not limited, but the mixing ratio of ethanol, that is, the addition amount of ethanol relative to the total mass of the ink is preferably in the range of 11.5% by mass or more and 40% by mass or less. According to such a configuration, the solubility of the fixing agent in the solvent is reliably reduced, and the fixing effect of the ink containing the above-mentioned specific coal-tar pigment is further improved. Therefore, more excellent light resistance can be imparted to the inkjet ink.

[0093] On the other hand, when the addition amount of ethanol is less than 11.5% by mass, the drying delay of the printed surface on the tablet surface increases, and sometimes such an adverse situation (transfer failure) may occur: when the printed tablets come into contact with each other, the undried ink adheres to another tablet and causes contamination. On the other hand, when the addition amount of ethanol exceeds 40% by mass, the ink at the inkjet nozzle dries, resulting in nozzle clogging of the inkjet head during printing, and thus the intermittent recoverability may be reduced.

[0094] In addition, in the inkjet ink according to the present embodiment, when propylene glycol is contained in the solvent, the mixing ratio of the propylene glycol, that is, the addition amount of propylene glycol, is preferably in the range of 0% by mass or more and 40% by mass or less with respect to the total mass of the ink. According to such a configuration, the solubility of the fixing agent in the solvent is reliably reduced, and the fixing effect of the ink containing the above specific tar-based pigment is further improved. Therefore, more excellent light resistance can be imparted to the inkjet ink. In addition, the addition amount of propylene glycol is more preferably 10% by mass or more. As a result, the solubility of the fixing agent in the solvent is further reliably reduced, and the fixing effect of the ink containing the above specific tar-based pigment is further improved. Therefore, further excellent light resistance can be imparted to the inkjet ink.

[0095] When the addition amount of propylene glycol exceeds 28% by mass, the drying delay of the printed surface on the tablet surface increases, and sometimes such a defect (transfer defect) occurs: when the printed tablets come into contact with each other, the undried ink adheres to another tablet and causes contamination.

[0096] In addition, the inkjet ink according to the present embodiment may further contain at least one of glycerin or isopropyl alcohol as a solvent. Specifically, in the above solvent, either glycerin or isopropyl alcohol may be further contained, or both glycerin and isopropyl alcohol may be further contained. Glycerin functions as a wetting agent in the same manner as the above propylene glycol. In addition, since isopropyl alcohol has high volatility like the above ethanol, the transfer resistance (drying property) of the inkjet ink can be improved. In addition to the above components, by further adding glycerin and isopropyl alcohol to the solvent, the light resistance of the inkjet ink can be further improved, and properties corresponding to each component can be imparted to the inkjet ink. In addition, by further containing these components in the solvent, the solubility of the fixing agent in the solvent is further reliably reduced, and the fixing effect of the ink containing the above specific tar-based pigment can be further improved.

[0097] (Internal addition resin)

[0098] In addition to the above pigments and solvents, the inkjet ink according to the present embodiment may also contain an internal addition resin. The internal addition resin that can be added to the inkjet ink according to the present embodiment is an edible, water-soluble powder, slurry, or flaky resinous substance, as long as it can form a film on the tablet surface through drying after printing. Examples of the above internal addition resin include: polyvinyl alcohol (PVA), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), polyvinylpyrrolidone (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.

[0099] (Leveling agent)

[0100] In addition to the above-mentioned pigments, solvents or internally added resins, the inkjet ink according to this embodiment may further contain a leveling agent. The leveling agent that can be added to the inkjet ink according to this embodiment may be any surfactant that is edible and water-soluble. As the above leveling agent, for example, polyglycerol fatty acid esters (such as decaglycerol distearate Q-182S manufactured by Sun Chemical Corporation, decaglycerol monolaurate Q-12S manufactured by the same company), sorbitan fatty acid esters (such as NIKKOL SL-10 manufactured by Nikko Chemicals Co., Ltd.), sucrose fatty acid esters (such as DK Ester F-110 manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), polysorbates (Emazole S-120 series manufactured by Kao Corporation), etc. can be cited.

[0101] 〔Printing method〕

[0102] The printing method of the inkjet ink according to this embodiment is not particularly limited, and it can be printing using a commercially available inkjet device such as an inkjet printer. Therefore, the inkjet ink according to this embodiment has a wide range of applications and is very useful. For example, the inkjet ink according to this embodiment can be printed by an inkjet device in a so-called drop-on-demand inkjet method using a piezoelectric element (piezoelectric ceramic) as an actuator, or can also be printed by an inkjet device of other methods.

[0103] As an inkjet device in the drop-on-demand inkjet method, for example, a device using a thermal inkjet method that ejects inkjet ink using steam pressure generated by instantaneously heating a micro heating element to a high temperature (200 to 300 °C); an electrostatic type device that ejects inkjet ink by electrostatic vibration of an actuator; a device using an ultrasonic method that utilizes the cavitation phenomenon of ultrasonic waves, etc. can be cited. In addition, if the inkjet ink according to this embodiment has chargeability, a device using a continuous jetting type (continuous method) can also be used.

[0104] 〔Tablet〕

[0105] In this embodiment, the above printing method can be used to print words and pictures on the surface of a tablet (for example) with the inkjet ink according to this embodiment. That is, the tablet according to this embodiment only needs to have a printed portion, that is, a printed image, printed with the inkjet ink according to this embodiment. According to the inkjet ink according to this embodiment, for example, the light resistance of a printed image (such as printed image 3) applied to the surface of a medical tablet by an inkjet printing method can be improved. Hereinafter, the configuration of a tablet having a printed image printed with the inkjet ink according to the embodiment will be described.

[0106] The tablets involved in this embodiment are, for example, medical tablets. Here, in addition to (for example) plain tablets (naked 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 tablets, etc.

[0107] Figure 2 It is a schematic cross-sectional view showing an example of a medical tablet (plain tablet) after printing (lettering, printing). Figure 2 A plain tablet print 5 in which a printed image 3 such as characters is printed on the upper surface of a tablet substrate 1 is shown in a sectional view.

[0108] Figure 3 It is a schematic cross-sectional view showing an example of a medical tablet (film-coated tablet) after printing (lettering, printing). Figure 3 A film-coated tablet print 9 in which a printed image 3 such as characters is printed on the upper surface of a tablet substrate 1 having a film coating layer 7 formed on its surface is shown in a sectional view.

[0109] It should be noted that in this embodiment, as Figure 4 shown, a solid image can be printed as the plain tablet printed image 11, and as Figure 5 shown, a two-dimensional barcode can be printed as the film-coated tablet printed image 13.

[0110] There is no particular limitation on the active ingredient contained in the medical tablet. For example, it contains substances effective for the prevention / treatment of various diseases (for example, substances having a sleep-inducing effect, sedative activity, antibacterial activity, antihypertensive effect, anti-hypertensive activity, analgesic effect, anti-inflammatory activity, mental stabilizing effect, diabetes treatment activity, diuretic effect, anticholinergic activity, anti-hyperacidity effect, antiepileptic effect, ACE inhibitory activity, β-receptor antagonist or agonist activity, anesthetic effect, appetite suppressant effect, anti-arrhythmic effect, antidepressant effect, anticoagulant activity, anti-diarrheal effect, antihistamine activity, antimalarial effect, anti-tumor activity, immunosuppressive activity, anti-Parkinson's disease effect, antipsychotic effect, antiplatelet activity, anti-hyperlipidemia effect, etc.), substances having a cleaning effect, fragrances, substances having a deodorizing effect, etc., but are not limited to these.

[0111] As needed, the tablets involved in this embodiment can be formulated with carriers permissible for their use together with the active ingredient. For example, if it is a medical tablet, a pharmaceutically permissible carrier can be formulated. As a pharmaceutically permissible carrier, various common organic or inorganic carrier substances used as raw materials for preparations can be used. For example, excipients, lubricants, binders, disintegrants, thickeners, etc. can be formulated in appropriate amounts. In addition, as needed, additives such as preservatives, antioxidants, colorants, sweeteners, etc. can also be used.

[0112] In this embodiment, a medical tablet as a tablet is taken as an example for illustration, but the present invention is not limited thereto. There is no particular limitation on the printing object of the inkjet ink according to this embodiment. For example, it can also be printed on the surfaces of various tablets such as tablets for animals other than humans (pets, livestock, poultry, etc.), feeds, fertilizers, detergents, tablet-shaped candies such as lemon-flavored candies, and health foods. In addition, there is no particular limitation on the size of the printing object of the inkjet ink according to this embodiment, and it can be applied to tablets of various sizes.

[0113] (Effect of this embodiment)

[0114] (1) The inkjet ink according to this embodiment contains Brilliant Blue FCF as a food dye, contains only trehalose as a fixing agent, contains water and ethanol as solvents, and the blending ratio of trehalose is in the range of 7.5% by mass or more and 20.0% by mass or less with respect to the total mass of the inkjet ink.

[0115] According to such a configuration, compared with the prior art, photochromic fading of a printed image using a specific colorant can be sufficiently suppressed, and excellent light resistance is imparted to the inkjet ink.

[0116] (2) The inkjet ink according to this embodiment contains Brilliant Blue FCF as a food dye, contains trehalose and isomaltulose as fixing agents, contains water and ethanol as solvents, the blending ratio of trehalose is in the range of 2.5% by mass or more and 15.0% by mass or less with respect to the total mass of the inkjet ink, and the blending ratio of isomaltulose is 10.0% by mass or less with respect to the total mass of the inkjet ink.

[0117] According to such a configuration, compared with the prior art, photochromic fading of a printed image using a specific colorant can be sufficiently suppressed, and excellent light resistance is imparted to the inkjet ink.

[0118] (3) In addition, when the inkjet ink according to this embodiment contains only trehalose as a fixing agent, the blending ratio of Brilliant Blue FCF can be in the range of 1.0% by mass or more and 15.0% by mass or less with respect to the total mass of the inkjet ink.

[0119] According to such a configuration, compared with the prior art, excellent light resistance can be imparted to the inkjet ink while high visibility and intermittent recoverability are imparted to the inkjet ink.

[0120] (4) In addition, when the inkjet ink according to this embodiment contains trehalose and isomaltulose as fixing agents, the blending ratio of Brilliant Blue FCF can be in the range of 1.0% by mass or more and 15.0% by mass or less with respect to the total mass of the inkjet ink.

[0121] According to such a configuration, compared with the prior art, excellent light resistance can be imparted to the inkjet ink while imparting high visibility and intermittent recoverability to the inkjet ink.

[0122] (5) The tablet print of the present embodiment includes a printed image (an example of a printed portion) 3 printed with the above-described inkjet ink.

[0123] According to such a configuration, compared with the prior art, photochromic fading of the printed image 3 directly printed on the surface of the tablet or the like can be sufficiently suppressed, and the light resistance of the printed image 3 can be sufficiently improved. In addition, edibility can be imparted to the printed image portion printed on the tablet surface.

[0124] [Examples]

[0125] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by any of the examples.

[0126] <Examples 1 to 63 and Comparative Examples 1 to 4>

[0127] Hereinafter, the preparation steps of the inkjet inks of Examples 1 to 63 and Comparative Examples 1 to 4 will be described.

[0128] (Manufacture of inkjet ink)

[0129] First, printing ink is prepared. The inkjet ink contains components such as a pigment (colorant), a solvent, and a fixing agent (fading inhibitor). As the preparation sequence, first, a fixing agent is added to the solvent to obtain a transparent base liquid. Then, a food dye is added to the transparent base liquid. Thus, the ink of the present embodiment is prepared. Hereinafter, each component will be specifically described.

[0130] In the present embodiment, purified water (ion-exchanged water), propylene glycol, and ethanol are respectively used as the solvent as needed. Specifically, propylene glycol and ethanol are added to purified water, and thoroughly stirred to obtain a solvent (mixed solvent). In addition, trehalose and reduced isomaltulose are added as a fixing agent (fading inhibitor) to the above solvent as needed, and stirred for about 1 hour to obtain a transparent base liquid. As a food dye, Blue No. 1, and Red No. 3, Red No. 102, and Yellow No. 4 are added to the above transparent base liquid as needed as colorants, thereby obtaining the inkjet inks of Examples 1 to 63 and Comparative Examples 1 to 4.

[0131] <Sample 1 (Comparative Example 1)>

[0132] With respect to the entire inkjet ink of Sample 1 (Comparative Example 1), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 49.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass.

[0133] In this way, the inkjet ink of Sample 1 (Comparative Example 1) was obtained.

[0134] <Sample 2 (Example 1)>

[0135] With respect to the entire inkjet ink of Sample 2 (Example 1), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 51.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of trehalose was set to 5.0% by mass.

[0136] In this way, the inkjet ink of Sample 2 (Example 1) was obtained.

[0137] <Sample 3 (Example 2)>

[0138] With respect to the entire inkjet ink of Sample 3 (Example 2), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 50.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of trehalose was set to 6.0% by mass.

[0139] In this way, the inkjet ink of Sample 3 (Example 2) was obtained.

[0140] <Sample 4 (Example 3)>

[0141] With respect to the entire inkjet ink of Sample 4 (Example 3), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 48.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of trehalose was set to 8.0% by mass.

[0142] In this way, the inkjet ink of Sample 4 (Example 3) was obtained.

[0143] <Sample 5 (Example 4)>

[0144] With respect to the entire inkjet ink of Sample 5 (Example 4), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 46.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0145] In this way, the inkjet ink of Sample 5 (Example 4) was obtained.

[0146] <Sample 6 (Example 5)>

[0147] With respect to the entire inkjet ink of Sample 6 (Example 5), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 44.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 5.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0148] In this way, the inkjet ink of Sample 6 (Example 5) was obtained.

[0149] <Sample 7 (Example 6)>

[0150] With respect to the entire inkjet ink of Sample 7 (Example 6), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 41.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 7.5% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0151] In this way, the inkjet ink of Sample 7 (Example 6) was obtained.

[0152] <Sample 8 (Example 7)>

[0153] With respect to the entire inkjet ink of Sample 8 (Example 7), the mixing ratio of Blue No. 1 as a coloring material was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 39.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0154] In this way, the inkjet ink of Sample 8 (Example 7) was obtained.

[0155] <Sample 9 (Example 8)>

[0156] With respect to the entire inkjet ink of Sample 9 (Example 8), the mixing ratio of Blue No. 1 as a coloring material was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 36.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 13.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0157] In this way, the inkjet ink of Sample 9 (Example 8) was obtained.

[0158] <Sample 10 (Example 9)>

[0159] With respect to the entire inkjet ink of Sample 10 (Example 9), the mixing ratio of Blue No. 1 as a coloring material was set to 1.5% by mass, the mixing ratio of Red No. 3 was set to 0.5% by mass, the mixing ratio of Red No. 102 was set to 0.5% by mass, the mixing ratio of Yellow No. 4 was set to 0.5% by mass. The mixing ratio of purified water in the solvent was set to 34.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 13.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0160] In this way, the inkjet ink of Sample 10 (Example 9) was obtained.

[0161] <Sample 11 (Example 10)>

[0162] With respect to the entire inkjet ink of Sample 11 (Example 10), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water among the solvents was set to 35.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 14.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0163] Thus, the inkjet ink of Sample 11 (Example 10) was obtained.

[0164] <Sample 12 (Example 11)>

[0165] With respect to the entire inkjet ink of Sample 12 (Example 11), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water among the solvents was set to 34.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 15.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0166] Thus, the inkjet ink of Sample 12 (Example 11) was obtained.

[0167] <Sample 13 (Comparative Example 2)>

[0168] With respect to the entire inkjet ink of Sample 13 (Comparative Example 2), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water among the solvents was set to 32.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 17.0% by mass, and the mixing ratio of reduced isomaltulose was set to 10.0% by mass.

[0169] Thus, the inkjet ink of Sample 13 (Comparative Example 2) was obtained.

[0170] <Sample 14 (Comparative Example 3)>

[0171] With respect to the entire inkjet ink of Sample 14 (Comparative Example 3), the mixing ratio of Blue No. 1 as a colorant was set to 3.0% by mass, the mixing ratio of purified water among the solvents was set to 52.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 5.0% by mass.

[0172] In this way, the inkjet ink of Sample 14 (Comparative Example 3) was obtained.

[0173] <Sample 15 (Example 12)>

[0174] With respect to the entire inkjet ink of Sample 15 (Example 12), the mixing ratio of Blue No. 1 as a colorant was set to 5.0% by mass, the mixing ratio of purified water in the solvent was set to 48.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 7.5% by mass.

[0175] In this way, the inkjet ink of Sample 15 (Example 12) was obtained.

[0176] <Sample 16 (Example 13)>

[0177] With respect to the entire inkjet ink of Sample 16 (Example 13), the mixing ratio of Blue No. 1 as a colorant was set to 5.0% by mass, the mixing ratio of purified water in the solvent was set to 45.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass.

[0178] In this way, the inkjet ink of Sample 16 (Example 13) was obtained.

[0179] <Sample 17 (Example 14)>

[0180] With respect to the entire inkjet ink of Sample 17 (Example 14), the mixing ratio of Blue No. 1 as a colorant was set to 3.0% by mass, the mixing ratio of purified water in the solvent was set to 45.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 12.0% by mass.

[0181] In this way, the inkjet ink of Sample 17 (Example 14) was obtained.

[0182] <Sample 18 (Example 15)>

[0183] With respect to the entire inkjet ink of Sample 18 (Example 15), the mixing ratio of Blue No. 1 as a colorant was set to 3.0% by mass, the mixing ratio of purified water in the solvent was set to 42.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 15.0% by mass.

[0184] In this way, the inkjet ink of Sample 18 (Example 15) was obtained.

[0185] <Sample 19 (Example 16)>

[0186] With respect to the entire inkjet ink of Sample 19 (Example 16), the mixing ratio of Blue No. 1 as a coloring material was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 43.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0187] In this way, the inkjet ink of Sample 19 (Example 16) was obtained.

[0188] <Sample 20 (Example 17)>

[0189] With respect to the entire inkjet ink of Sample 20 (Example 17), the mixing ratio of Blue No. 1 as a coloring material was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 41.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 18.0% by mass.

[0190] In this way, the inkjet ink of Sample 20 (Example 17) was obtained.

[0191] <Sample 21 (Example 18)>

[0192] With respect to the entire inkjet ink of Sample 21 (Example 18), the mixing ratio of Blue No. 1 as a coloring material was set to 1.5% by mass, the mixing ratio of Red No. 3 was set to 0.5% by mass, the mixing ratio of Red No. 102 was set to 0.5% by mass, the mixing ratio of Yellow No. 4 was set to 0.5% by mass, the mixing ratio of purified water in the solvent was set to 39.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 18.0% by mass.

[0193] In this way, the inkjet ink of Sample 21 (Example 18) was obtained.

[0194] <Sample 22 (Example 19)>

[0195] With respect to the entire inkjet ink of Sample 22 (Example 19), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 39.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 20.0% by mass.

[0196] In this way, the inkjet ink of Sample 22 (Example 19) was obtained.

[0197] <Sample 23 (Comparative Example 4)>

[0198] With respect to the entire inkjet ink of Sample 23 (Comparative Example 4), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 37.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 22.0% by mass.

[0199] In this way, the inkjet ink of Sample 23 (Comparative Example 4) was obtained.

[0200] <Sample 24 (Example 20)>

[0201] With respect to the entire inkjet ink of Sample 24 (Example 20), the mixing ratio of Blue No. 1 as a colorant was set to 0.7% by mass, the mixing ratio of purified water in the solvent was set to 35.8% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 15.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0202] In this way, the inkjet ink of Sample 24 (Example 20) was obtained.

[0203] <Sample 25 (Example 21)>

[0204] With respect to the entire inkjet ink of Sample 25 (Example 21), the mixing ratio of Blue No. 1 as a colorant was set to 1.0% by mass, the mixing ratio of purified water in the solvent was set to 35.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 15.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0205] Thus, the inkjet ink of Sample 25 (Example 21) was obtained.

[0206] <Sample 26 (Example 22)>

[0207] With respect to the entire inkjet ink of Sample 26 (Example 22), the mixing ratio of C.I. Blue 1 as a coloring material was set to 1.2% by mass, the mixing ratio of purified water in the solvent was set to 35.3% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 15.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0208] Thus, the inkjet ink of Sample 26 (Example 22) was obtained.

[0209] <Sample 27 (Example 23)>

[0210] With respect to the entire inkjet ink of Sample 27 (Example 23), the mixing ratio of C.I. Blue 1 as a coloring material was set to 1.5% by mass, the mixing ratio of purified water in the solvent was set to 40.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0211] Thus, the inkjet ink of Sample 27 (Example 23) was obtained.

[0212] <Sample 28 (Example 24)>

[0213] With respect to the entire inkjet ink of Sample 28 (Example 24), the mixing ratio of C.I. Blue 1 as a coloring material was set to 2.0% by mass, the mixing ratio of purified water in the solvent was set to 39.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0214] Thus, the inkjet ink of Sample 28 (Example 24) was obtained.

[0215] <Sample 29 (Example 25)>

[0216] With respect to the entire inkjet ink of Sample 29 (Example 25), the mixing ratio of Blue No. 1 as a colorant was set to 2.0% by mass, the mixing ratio of Red No. 3 was set to 0.5% by mass, the mixing ratio of Red No. 102 was set to 0.5% by mass, the mixing ratio of Yellow No. 4 was set to 0.5% by mass, the mixing ratio of purified water in the solvent was set to 38.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0217] In this way, the inkjet ink of Sample 29 (Example 25) was obtained.

[0218] <Sample 30 (Example 26)>

[0219] With respect to the entire inkjet ink of Sample 30 (Example 26), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water in the solvent was set to 38.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0220] In this way, the inkjet ink of Sample 30 (Example 26) was obtained.

[0221] <Sample 31 (Example 27)>

[0222] With respect to the entire inkjet ink of Sample 31 (Example 27), the mixing ratio of Blue No. 1 as a colorant was set to 4.5% by mass, the mixing ratio of purified water in the solvent was set to 42.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 5.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0223] In this way, the inkjet ink of Sample 31 (Example 27) was obtained.

[0224] <Sample 32 (Example 28)>

[0225] With respect to the entire inkjet ink of Sample 32 (Example 28), the mixing ratio of Blue No. 1 as a colorant was set to 5.0% by mass, the mixing ratio of purified water among the solvents was set to 41.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 5.0% by mass, and the mixing ratio of reduced isomaltulose was set to 9.0% by mass.

[0226] Thus, the inkjet ink of Sample 32 (Example 28) was obtained.

[0227] <Sample 33 (Example 29)>

[0228] With respect to the entire inkjet ink of Sample 33 (Example 29), the mixing ratio of Blue No. 1 as a colorant was set to 10.0% by mass, the mixing ratio of purified water among the solvents was set to 43.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of reduced isomaltulose was set to 5.0% by mass.

[0229] Thus, the inkjet ink of Sample 33 (Example 29) was obtained.

[0230] <Sample 34 (Example 30)>

[0231] With respect to the entire inkjet ink of Sample 34 (Example 30), the mixing ratio of Blue No. 1 as a colorant was set to 15.0% by mass, the mixing ratio of purified water among the solvents was set to 38.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of reduced isomaltulose was set to 5.0% by mass.

[0232] Thus, the inkjet ink of Sample 34 (Example 30) was obtained.

[0233] <Sample 35 (Example 31)>

[0234] With respect to the entire inkjet ink of Sample 35 (Example 31), the mixing ratio of Blue No. 1 as a colorant was set to 17.0% by mass, the mixing ratio of purified water among the solvents was set to 36.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 2.5% by mass, and the mixing ratio of reduced isomaltulose was set to 5.0% by mass.

[0235] Thus, the inkjet ink of Sample 35 (Example 31) was obtained.

[0236] <Sample 36 (Example 32)>

[0237] With respect to the entire inkjet ink of Sample 36 (Example 32), the mixing ratio of Blue No. 1 as a colorant was set to 0.7% by mass, the mixing ratio of purified water in the solvent was set to 39.8% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 20.0% by mass.

[0238] Thus, the inkjet ink of Sample 36 (Example 32) was obtained.

[0239] <Sample 37 (Example 33)>

[0240] With respect to the entire inkjet ink of Sample 37 (Example 33), the mixing ratio of Blue No. 1 as a colorant was set to 1.0% by mass, the mixing ratio of purified water in the solvent was set to 39.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 20.0% by mass.

[0241] Thus, the inkjet ink of Sample 37 (Example 33) was obtained.

[0242] <Sample 38 (Example 34)>

[0243] With respect to the entire inkjet ink of Sample 38 (Example 34), the mixing ratio of Blue No. 1 as a colorant was set to 1.2% by mass, the mixing ratio of purified water in the solvent was set to 39.3% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 20.0% by mass.

[0244] Thus, the inkjet ink of Sample 38 (Example 34) was obtained.

[0245] <Sample 39 (Example 35)>

[0246] With respect to the entire inkjet ink of Sample 39 (Example 35), the mixing ratio of Blue No. 1 as a colorant was set to 1.5% by mass, the mixing ratio of purified water among the solvents was set to 39.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 20.0% by mass.

[0247] Thus, the inkjet ink of Sample 39 (Example 35) was obtained.

[0248] <Sample 40 (Example 36)>

[0249] With respect to the entire inkjet ink of Sample 40 (Example 36), the mixing ratio of Blue No. 1 as a colorant was set to 2.0% by mass, the mixing ratio of purified water among the solvents was set to 38.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 20.0% by mass.

[0250] Thus, the inkjet ink of Sample 40 (Example 36) was obtained.

[0251] <Sample 41 (Example 37)>

[0252] With respect to the entire inkjet ink of Sample 41 (Example 37), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 41.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0253] Thus, the inkjet ink of Sample 41 (Example 37) was obtained.

[0254] <Sample 42 (Example 38)>

[0255] With respect to the entire inkjet ink of Sample 42 (Example 38), the mixing ratio of Blue No. 1 as a colorant was set to 4.5% by mass, the mixing ratio of purified water among the solvents was set to 40.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0256] Thus, the inkjet ink of Sample 42 (Example 38) was obtained.

[0257] <Sample 43 (Example 39)>

[0258] With respect to the entire inkjet ink of Sample 43 (Example 39), the mixing ratio of C.I. Blue 1 as a coloring material is set to 4.5% by mass, the mixing ratio of C.I. Red 3 is set to 0.5% by mass, the mixing ratio of C.I. Red 102 is set to 0.5% by mass, the mixing ratio of C.I. Yellow 4 is set to 0.5% by mass, the mixing ratio of purified water in the solvent is set to 39.5% by mass, the mixing ratio of ethanol is set to 11.5% by mass, the mixing ratio of propylene glycol (PG) is set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) is set to 15.0% by mass.

[0259] Thus, the inkjet ink of Sample 43 (Example 39) was obtained.

[0260] <Sample 44 (Example 40)>

[0261] With respect to the entire inkjet ink of Sample 44 (Example 40), the mixing ratio of C.I. Blue 1 as a coloring material is set to 5.0% by mass, the mixing ratio of purified water in the solvent is set to 40.5% by mass, the mixing ratio of ethanol is set to 11.5% by mass, the mixing ratio of propylene glycol (PG) is set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) is set to 15.0% by mass.

[0262] Thus, the inkjet ink of Sample 44 (Example 40) was obtained.

[0263] <Sample 45 (Example 41)>

[0264] With respect to the entire inkjet ink of Sample 45 (Example 41), the mixing ratio of C.I. Blue 1 as a coloring material is set to 10.0% by mass, the mixing ratio of purified water in the solvent is set to 40.5% by mass, the mixing ratio of ethanol is set to 11.5% by mass, the mixing ratio of propylene glycol (PG) is set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) is set to 10.0% by mass.

[0265] Thus, the inkjet ink of Sample 45 (Example 41) was obtained.

[0266] <Sample 46 (Example 42)>

[0267] With respect to the entire inkjet ink of Sample 46 (Example 42), the mixing ratio of Blue No. 1 as a colorant was set to 15.0% by mass, the mixing ratio of purified water among the solvents was set to 37.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 8.0% by mass.

[0268] Thus, the inkjet ink of Sample 46 (Example 42) was obtained.

[0269] <Sample 47 (Example 43)>

[0270] With respect to the entire inkjet ink of Sample 47 (Example 43), the mixing ratio of Blue No. 1 as a colorant was set to 17.0% by mass, the mixing ratio of purified water among the solvents was set to 35.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 8.0% by mass.

[0271] Thus, the inkjet ink of Sample 47 (Example 43) was obtained.

[0272] <Sample 48 (Example 44)>

[0273] With respect to the entire inkjet ink of Sample 48 (Example 44), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 59.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0274] Thus, the inkjet ink of Sample 48 (Example 44) was obtained.

[0275] <Sample 49 (Example 45)>

[0276] With respect to the entire inkjet ink of Sample 49 (Example 45), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 50.5% by mass, the mixing ratio of ethanol was set to 20.0% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0277] Thus, the inkjet ink of Sample 49 (Example 45) was obtained.

[0278] <Sample 50 (Example 46)>

[0279] With respect to the entire inkjet ink of Sample 50 (Example 46), the mixing ratio of Pigment Blue 1 as a colorant was set to 3.5% by mass, the mixing ratio of Pigment Red 3 was set to 0.5% by mass, the mixing ratio of Pigment Red 102 was set to 0.5% by mass, the mixing ratio of Pigment Yellow 4 was set to 0.5% by mass. The mixing ratio of purified water in the solvent was set to 49.0% by mass, the mixing ratio of ethanol was set to 20.0% by mass, and the mixing ratio of propylene glycol (PG) was set to 10.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0280] Thus, the inkjet ink of Sample 50 (Example 46) was obtained.

[0281] <Sample 51 (Example 47)>

[0282] With respect to the entire inkjet ink of Sample 51 (Example 47), the mixing ratio of Pigment Blue 1 as a colorant was set to 3.5% by mass. The mixing ratio of purified water in the solvent was set to 40.5% by mass, the mixing ratio of ethanol was set to 30.0% by mass, and the mixing ratio of propylene glycol (PG) was set to 10.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0283] Thus, the inkjet ink of Sample 51 (Example 47) was obtained.

[0284] <Sample 52 (Example 48)>

[0285] With respect to the entire inkjet ink of Sample 52 (Example 48), the mixing ratio of Pigment Blue 1 as a colorant was set to 3.5% by mass. The mixing ratio of purified water in the solvent was set to 30.5% by mass, the mixing ratio of ethanol was set to 40.0% by mass, and the mixing ratio of propylene glycol (PG) was set to 10.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0286] Thus, the inkjet ink of Sample 52 (Example 48) was obtained.

[0287] <Sample 53 (Example 49)>

[0288] With respect to the entire inkjet ink of Sample 53 (Example 49), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 69.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0289] Thus, the inkjet ink of Sample 53 (Example 49) was obtained.

[0290] <Sample 54 (Example 50)>

[0291] With respect to the entire inkjet ink of Sample 54 (Example 50), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of Red No. 3 was set to 0.5% by mass, the mixing ratio of Red No. 102 was set to 0.5% by mass, the mixing ratio of Yellow No. 4 was set to 0.5% by mass. The mixing ratio of purified water among the solvents was set to 67.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0292] Thus, the inkjet ink of Sample 54 (Example 50) was obtained.

[0293] <Sample 55 (Example 51)>

[0294] With respect to the entire inkjet ink of Sample 55 (Example 51), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 59.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, and the mixing ratio of propylene glycol (PG) was set to 10.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0295] Thus, the inkjet ink of Sample 55 (Example 51) was obtained.

[0296] <Sample 56 (Example 52)>

[0297] With respect to the entire inkjet ink of Sample 56 (Example 52), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 49.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 20.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0298] Thus, the inkjet ink of Sample 56 (Example 52) was obtained.

[0299] <Sample 57 (Example 53)>

[0300] With respect to the entire inkjet ink of Sample 57 (Example 53), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 41.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 10.0% by mass, and the mixing ratio of reduced isomaltulose was set to 6.0% by mass.

[0301] Thus, the inkjet ink of Sample 57 (Example 53) was obtained.

[0302] <Sample 58 (Example 54)>

[0303] With respect to the entire inkjet ink of Sample 58 (Example 54), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 59.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0304] Thus, the inkjet ink of Sample 58 (Example 54) was obtained.

[0305] <Sample 59 (Example 55)>

[0306] With respect to the entire inkjet ink of Sample 59 (Example 55), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 50.5% by mass, the mixing ratio of ethanol was set to 20.0% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass. In addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0307] In this way, the inkjet ink of Sample 59 (Example 55) was obtained.

[0308] <Sample 60 (Example 56)>

[0309] With respect to the entire inkjet ink of Sample 60 (Example 56), the mixing ratio of C.I. Blue 1 as a colorant was set to 3.5% by mass, the mixing ratio of C.I. Red 3 was set to 0.5% by mass, the mixing ratio of C.I. Red 102 was set to 0.5% by mass, the mixing ratio of C.I. Yellow 4 was set to 0.5% by mass, the mixing ratio of purified water in the solvent was set to 49.0% by mass, the mixing ratio of ethanol was set to 20.0% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0310] In this way, the inkjet ink of Sample 60 (Example 56) was obtained.

[0311] <Sample 61 (Example 57)>

[0312] With respect to the entire inkjet ink of Sample 61 (Example 57), the mixing ratio of C.I. Blue 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water in the solvent was set to 40.5% by mass, the mixing ratio of ethanol was set to 30.0% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0313] In this way, the inkjet ink of Sample 61 (Example 57) was obtained.

[0314] <Sample 62 (Example 58)>

[0315] With respect to the entire inkjet ink of Sample 62 (Example 58), the mixing ratio of C.I. Blue 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water in the solvent was set to 30.5% by mass, the mixing ratio of ethanol was set to 40.0% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0316] In this way, the inkjet ink of Sample 62 (Example 58) was obtained.

[0317] <Sample 63 (Example 59)>

[0318] With respect to the entire inkjet ink of Sample 63 (Example 59), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 69.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0319] Thus, the inkjet ink of Sample 63 (Example 59) was obtained.

[0320] <Sample 64 (Example 60)>

[0321] With respect to the entire inkjet ink of Sample 64 (Example 60), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of Red No. 3 was set to 0.5% by mass, the mixing ratio of Red No. 102 was set to 0.5% by mass, the mixing ratio of Yellow No. 4 was set to 0.5% by mass, the mixing ratio of purified water among the solvents was set to 67.5% by mass, the mixing ratio of ethanol was set to 11.5% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0322] Thus, the inkjet ink of Sample 64 (Example 60) was obtained.

[0323] <Sample 65 (Example 61)>

[0324] With respect to the entire inkjet ink of Sample 65 (Example 61), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 59.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 10.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0325] Thus, the inkjet ink of Sample 65 (Example 61) was obtained.

[0326] <Sample 66 (Example 62)>

[0327] With respect to the entire inkjet ink of Sample 66 (Example 62), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 49.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 20.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0328] Thus, the inkjet ink of Sample 66 (Example 62) was obtained.

[0329] <Sample 67 (Example 63)>

[0330] With respect to the entire inkjet ink of Sample 67 (Example 63), the mixing ratio of Blue No. 1 as a colorant was set to 3.5% by mass, the mixing ratio of purified water among the solvents was set to 41.0% by mass, the mixing ratio of ethanol was set to 11.5% by mass, the mixing ratio of propylene glycol (PG) was set to 28.0% by mass, and in addition, the mixing ratio of trehalose as a fixing agent (fading inhibitor) was set to 16.0% by mass.

[0331] Thus, the inkjet ink of Sample 67 (Example 63) was obtained.

[0332] By passing each of the inks of the above Examples 1 to 63 and Comparative Examples 1 to 4 through a membrane filter to remove solid foreign matters in the liquid. Specifically, it was passed through a membrane filter (cellulose acetate membrane) with a pore size of 5.0 μm once, and then passed through a membrane filter (cellulose acetate membrane) with a pore size of 0.8 μm once, thereby obtaining refined inks respectively.

[0333] <Evaluation>

[0334] Regarding the above refined inks of the inks of the above Examples and Comparative Examples, the lightfastness (ΔE, readability) and printability were evaluated by the following methods. The evaluation results are shown in Tables 1 to 6 described later together with the ink compositions of the above Examples and Comparative Examples.

[0335] (Lightfastness test)

[0336] 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 nozzle number of 2,656, the refined inks of the above Examples 1 to 63 and Comparative Examples 1 to 4 were printed on the following tablets with a printing droplet volume of 6 pl per drop.

[0337] The tablets to be printed were set as test film-coated tablets (base: treated starch, coating agent: 70% hydroxypropyl methylcellulose / 30% titanium oxide mixture, diameter: 6.5 mm). In addition, the printed image was set as a circular solid image (diameter 4.0 mm). Thus, a film-coated tablet print was obtained.

[0338] It should be noted that the lightfastness test was carried out in an environment where the ambient humidity of the testing machine was set to 60% RH (25 °C).

[0339] Using a light stability test apparatus (Nagano Science LT-120A-WD), visible light with an accumulated illuminance of 1.2 million lux was irradiated onto the above-mentioned film-coated tablet prints of each example and each comparative example for which chromaticity and optical color density had been measured. The chromaticity and optical color density of the film-coated tablet prints irradiated with visible light were measured using a spectrophotometer, and the color difference ΔE (a value obtained according to JIS Z 8781), which represents the change amount of chromaticity and optical color density before and after visible light irradiation, was compared. The comparison results are shown in Tables 1 to 6. As described above, regarding the change in hue before and after visible light irradiation, the inventors derived that if the color difference ΔE of JIS Z 8781 is 25 or less (ΔE ≤ 25), photochromic fading is sufficiently suppressed, and thus excellent light resistance is exhibited. In addition, it was derived that if the color difference ΔE is 25 or less (ΔE ≤ 25), excellent readability is also exhibited. Therefore, if ΔE ≤ 25, the inkjet ink has excellent light resistance and readability and is qualified in this evaluation.

[0340] It should be noted that the evaluation criteria for readability are as follows.

[0341] ◎: ΔE ≤ 15

[0342] 〇: ΔE ≤ 20

[0343] △: ΔE ≤ 25

[0344] ×: ΔE > 25

[0345] (Printability: Initial ejection)

[0346] An on-demand inkjet head driven by a piezoelectric ceramic with a print resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (the conveyance direction of recording media such as tablets), and a total of 2,656 nozzles was used. Using the above inkjet head, a test pattern was printed immediately after nozzle maintenance. Then, according to the printing condition of the test pattern, the readability of the printed image accompanied by the ejection failure area was confirmed. The evaluation criteria are as follows.

[0347] ○: No ejection failure

[0348] △: Readable

[0349] ×: Unreadable

[0350] It should be noted that if the evaluation of initial ejectability is "○" or "△", there is no problem in use, so it is considered qualified.

[0351] The compositions and evaluation results of the inkjet inks of each example and each comparative example are shown in Tables 1 to 6. It should be noted that the "blank" part in Tables 1 to 6 indicates that the substance was not used. In addition, all units in Tables 1 to 6 are "mass %".

[0352] [Table 1]

[0353]

[0354] [Table 2]

[0355]

[0356] [Table 3]

[0357]

[0358] [Table 4]

[0359]

[0360] [Table 5]

[0361]

[0362] [Table 6]

[0363]

[0364] As shown in Tables 1 to 6, in the film-coated tablet prints of Examples 1 to 63, as a result of the lightfastness test, the color difference ΔE before and after visible light irradiation was 25 or less (ΔE ≤ 25). Specifically, in the film-coated tablet prints of Examples 1 to 63, the color difference ΔE before and after visible light irradiation was in the range of 2.2 to 24.6 and was less than 25. That is, it can be seen that the inkjet inks of Examples 1 to 63 sufficiently suppress the photochromic fading of the printed image and impart excellent lightfastness. In contrast, as shown in Tables 1 to 6, in the film-coated tablet prints of Comparative Examples 1 to 4, as a result of the lightfastness test, the color difference ΔE before and after visible light irradiation was a value exceeding 25 (ΔE > 25) or was not measurable. That is, it can be seen that the inkjet inks of Comparative Examples 1 to 4 cannot sufficiently suppress the photochromic fading of the printed image and have insufficient lightfastness.

[0365] From the results of the above lightfastness test, it can be seen that if an inkjet ink contains Blue No. 1 as a food dye, contains only trehalose as a fixing agent, contains water and ethanol as solvents, and the mixing ratio of trehalose is in the range of 7.5% by mass or more and 20.0% by mass or less with respect to the total mass of the inkjet ink, then the photochromic fading of the printed image can be sufficiently suppressed and excellent lightfastness can be imparted.

[0366] In addition, from the results of the above lightfastness test, it can be seen that for an inkjet ink containing Blue No. 1 as an edible dye, containing trehalose and reduced isomaltulose as fixing agents, containing water and ethanol as solvents, where the blending ratio of trehalose is in the range of 2.5% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink, and the blending ratio of reduced isomaltulose is 10.0% by mass or less relative to the total mass of the inkjet ink, photochromic fading of the printed image can be sufficiently suppressed, and excellent lightfastness can be imparted.

[0367] In addition, as shown in Tables 1 to 6, in the inkjet inks of Examples 1 to 63, the evaluation results of printability (initial ejection) were all "Δ" or more, indicating that they have sufficient printability (initial ejection) while having excellent lightfastness.

[0368] In addition, for example, the present invention can adopt the following constitution. (1)

[0370] An inkjet ink, characterized in that

[0371] it contains Blue No. 1 as an edible dye, contains only trehalose as a fixing agent, and contains water and ethanol as solvents,

[0372] and the blending ratio of the trehalose is in the range of 7.5% by mass or more and 20.0% by mass or less relative to the total mass of the inkjet ink. (2)

[0374] An inkjet ink, characterized in that

[0375] it contains Blue No. 1 as an edible dye, contains only trehalose as a fixing agent, and contains water and ethanol as solvents,

[0376] and the blending ratio of the trehalose is in the range of 15.0% by mass or more and 20.0% by mass or less relative to the total mass of the inkjet ink. (3)

[0378] An inkjet ink, characterized in that

[0379] it contains Blue No. 1 as an edible dye, contains only trehalose as a fixing agent, and contains water and ethanol as solvents,

[0380] and the blending ratio of the trehalose is in the range of 15.0% by mass or more and 18.0% by mass or less relative to the total mass of the inkjet ink. (4)

[0382] An inkjet ink, characterized in that

[0383] Containing Brilliant Blue FCF as a food dye, containing trehalose and isomaltulose as fixatives, and containing water and ethanol as solvents,

[0384] The mixing ratio of the trehalose is in the range of 2.5% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink.

[0385] The mixing ratio of the isomaltulose is 10.0% by mass or less relative to the total mass of the inkjet ink. (5)

[0387] An inkjet ink, characterized in that,

[0388] Containing Brilliant Blue FCF as a food dye, containing trehalose and isomaltulose as fixatives, and containing water and ethanol as solvents,

[0389] The mixing ratio of the trehalose is in the range of 5.0% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink.

[0390] The mixing ratio of the isomaltulose is 10.0% by mass or less relative to the total mass of the inkjet ink. (6)

[0392] An inkjet ink, characterized in that,

[0393] Containing Brilliant Blue FCF as a food dye, containing trehalose and isomaltulose as fixatives, and containing water and ethanol as solvents,

[0394] The mixing ratio of the trehalose is in the range of 7.5% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink.

[0395] The mixing ratio of the isomaltulose is 8.0% by mass or more and 10.0% by mass or less relative to the total mass of the inkjet ink. (7)

[0397] The inkjet ink according to any one of (1) to (6) above, characterized in that the mixing ratio of the Brilliant Blue FCF is in the range of 1.0% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink. (8)

[0399] The inkjet ink according to any one of (1) to (6) above, characterized in that the mixing ratio of the Brilliant Blue FCF is in the range of 1.0% by mass or more and 5.0% by mass or less relative to the total mass of the inkjet ink. (9)

[0401] An inkjet ink, characterized in that,

[0402] containing Blue No. 1 as an edible dye, containing only trehalose as a fixing agent, containing water and ethanol as solvents,

[0403] the mixing ratio of the Blue No. 1 is in the range of 3.5% by mass or more and 17.0% by mass or less relative to the total mass of the inkjet ink,

[0404] the mixing ratio of the trehalose is in the range of 8.0% by mass or more and 16.0% by mass or less relative to the total mass of the inkjet ink. (10)

[0406] An inkjet ink, characterized in that,

[0407] containing Blue No. 1 as an edible dye, containing trehalose and reduced isomaltulose as fixing agents, containing water and ethanol as solvents,

[0408] the mixing ratio of the Blue No. 1 is in the range of 1.5% by mass or more and 17.0% by mass or less relative to the total mass of the inkjet ink,

[0409] the mixing ratio of the trehalose is in the range of 2.5% by mass or more and 15.0% by mass or less relative to the total mass of the inkjet ink,

[0410] the mixing ratio of the reduced isomaltulose is 5.0% by mass or more and 10.0% by mass or less relative to the total mass of the inkjet ink. (11)

[0412] The inkjet ink according to any one of the above (1) to (10), characterized in that,

[0413] further containing propylene glycol as the solvent,

[0414] the mixing ratio of the propylene glycol is 28.0% by mass or less relative to the total mass of the inkjet ink. (12)

[0416] A tablet print having a printed portion printed with the inkjet ink according to any one of the above (1) to (11).

[0417] The scope of the present invention is not limited to the exemplary embodiments described in the drawings, but includes all embodiments having an equivalent effect to the object of the present invention. In addition, the scope of the present invention is not limited to the combination of features of the invention defined by the claims, but can be defined by all desired combinations of specific features among each of the features disclosed.

Claims

1. An inkjet ink, characterized in that Contains Blue No. 1 as food dye, only trehalose as a fixative, and water and ethanol as solvents. The blending ratio of the trehalose is within a range of 7.5 mass % to 20.0 mass % based on the total mass of the inkjet ink.

2. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, only trehalose as a fixative, and water and ethanol as solvents. The blending ratio of the trehalose is within a range of 15.0 mass % to 20.0 mass % based on the total mass of the inkjet ink.

3. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, only trehalose as a fixative, and water and ethanol as solvents. The blending ratio of the trehalose is within a range of 15.0 mass % to 18.0 mass % based on the total mass of the inkjet ink.

4. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, trehalose and reduced isomaltulose as fixatives, and water and ethanol as solvents. The mixing ratio of the trehalose is in a range of 2.5 mass % to 15.0 mass % based on the total mass of the inkjet ink. The blending ratio of the reduced isomaltulose is 10.0% by mass or less based on the total mass of the inkjet ink.

5. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, trehalose and reduced isomaltulose as fixatives, and water and ethanol as solvents. The mixing ratio of the trehalose is in the range of 5.0 mass % to 15.0 mass % based on the total mass of the inkjet ink. The blending ratio of the reduced isomaltulose is 10.0% by mass or less based on the total mass of the inkjet ink.

6. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, trehalose and reduced isomaltulose as fixatives, and water and ethanol as solvents. The mixing ratio of the trehalose is in the range of 7.5 mass % to 15.0 mass % based on the total mass of the inkjet ink. The blending ratio of the reduced isomaltulose is 8.0 mass % or more and 10.0 mass % or less based on the total mass of the inkjet ink.

7. The inkjet ink according to claim 1, characterized in that The blending ratio of the blue No. 1 is within a range of 1.0 mass % to 15.0 mass % based on the total mass of the inkjet ink.

8. The inkjet ink according to claim 3, characterized in that The blending ratio of the blue No. 1 is within a range of 1.0 mass % to 5.0 mass % based on the total mass of the inkjet ink.

9. The inkjet ink according to claim 4, characterized in that The blending ratio of the blue No. 1 is within a range of 1.0 mass % to 15.0 mass % based on the total mass of the inkjet ink.

10. The inkjet ink according to claim 6, characterized in that The blending ratio of the blue No. 1 is within a range of 1.0 mass % to 5.0 mass % based on the total mass of the inkjet ink.

11. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, only trehalose as a fixative, and water and ethanol as solvents. The mixing ratio of the blue No. 1 is in the range of 3.5 mass % to 17.0 mass % relative to the total mass of the inkjet ink. The blending ratio of the trehalose is within a range of 8.0 mass % to 16.0 mass % based on the total mass of the inkjet ink.

12. An inkjet ink, characterized in that: Contains Blue No. 1 as food dye, trehalose and reduced isomaltulose as fixatives, and water and ethanol as solvents. The mixing ratio of the blue No. 1 is in the range of 1.5 mass % to 17.0 mass % relative to the total mass of the inkjet ink. The mixing ratio of the trehalose is in a range of 2.5 mass % to 15.0 mass % based on the total mass of the inkjet ink. The blending ratio of the reduced isomaltulose is 5.0 mass % or more and 10.0 mass % or less based on the total mass of the inkjet ink.

13. The inkjet ink according to claim 11, characterized in that further comprising propylene glycol as the solvent, The blending ratio of the propylene glycol is 28.0% by mass or less based on the total mass of the inkjet ink.

14. The inkjet ink according to claim 12, characterized in that further comprising propylene glycol as the solvent, The blending ratio of the propylene glycol is 28.0% by mass or less based on the total mass of the inkjet ink. 15 . A tablet printed article comprising a printed portion obtained by printing with the inkjet ink according to claim 1 .

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