JP2019182943A - Inkjet ink and tablet - Google Patents

Abstract

To provide an inkjet ink capable of reducing reduction of printing resumption property even when dryness is enhanced by increasing added amount of an alcohol solvent in a carbon inkjet ink, and a tablet having a printed part printed by the inkjet ink.SOLUTION: The inkjet ink is an inkjet ink containing water, an alcohol solvent, carbon, and a dispersant, the alcohol solvent contains at least one of isopropyl alcohol and normal propyl alcohol, concentration of the alcohol solvent is 35 pts.mass or less based on whole inkjet ink, the dispersant contains sucrose fatty acid ester having HLB value in a range of 11 to 20, and content of the sucrose fatty acid ester is 48 mass% to 100 mass% based on carbon.SELECTED DRAWING: None

Description

  The present invention relates to inkjet inks and tablets.

Some inks for ink jet printing (hereinafter also simply referred to as “ink jet inks”) have edible properties. And as a technique regarding the ink jet ink which has edible property, there exists what was described in patent document 1, for example.
Examples of edible ink-jet inks include those containing an alcohol solvent. In addition, edible inkjet inks include, for example, those containing carbon such as vegetable charcoal pigment as a black pigment.

JP 2006-169301 A

  An ink-jet ink containing carbon (hereinafter, also simply referred to as “carbon ink-jet ink”) may be required to have a performance of drying the ink after printing, so-called dryness. As a method for improving this performance, for example, there is a method of adding an alcohol solvent having high drying property to the inkjet ink and increasing the amount of the alcohol solvent added. However, this method may deteriorate the print resumability. Note that the above-described print resumability is sometimes referred to as intermittent print resumability.

  On the other hand, when printing is performed using a carbon inkjet ink in which the amount of alcohol solvent added is reduced, the above-described print resumability is improved, but, for example, the ink drying property tends to be reduced. For this reason, for example, when characters or the like are printed on tablets having low drying properties such as film-coated tablets (FC tablets) or sugar-coated tablets using ink-jet inks in which the amount of alcohol solvent added is reduced, the ink has low drying properties. As a result, the ink may be transferred to printing press members or other tablets.

  The present invention has been made in view of the above circumstances, and even when the amount of alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the decrease in printing resumability. It is an object of the present invention to provide an ink jet ink that can be used and a tablet including a printing unit that is printed with the ink jet ink.

  An inkjet ink according to one embodiment of the present invention is an inkjet ink containing water, an alcohol solvent, carbon, and a dispersant, wherein the alcohol solvent contains at least one of isopropyl alcohol and normal propyl alcohol, The concentration of the alcohol solvent is 35 parts by mass or less with respect to the entire inkjet ink, and the dispersant contains a sucrose fatty acid ester having an HLB value in the range of 11 to 20, The content is in the range of 48% by mass to 100% by mass with respect to the carbon.

  According to one embodiment of the present invention, even when the amount of an alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the decrease in printing resumability.

It is the top view and sectional drawing which show the 1st structural example of the medical tablet which concerns on this embodiment. It is the top view and sectional drawing which show the 2nd structural example of the medical tablet which concerns on this embodiment.

  The inkjet ink which concerns on embodiment of this invention is related with the inkjet ink used when printing a character, an image, etc. on the surface of a medical tablet by the inkjet printing method, for example. Hereinafter, the structure of the tablet provided with the inkjet part which concerns on embodiment of this invention and the printing part printed with the inkjet ink is demonstrated in detail.

[Configuration of inkjet ink]
The inkjet ink according to this embodiment includes at least water, an alcohol solvent, carbon, and a dispersant. The alcohol solvent according to this embodiment includes at least one of isopropyl alcohol (IPA) and normal propyl alcohol (NPA), and the content (concentration) thereof is 35 parts by mass or less with respect to the entire inkjet ink. Further, the dispersant according to the present embodiment includes a sucrose fatty acid ester having an HLB value in the range of 11 or more and 20 or less, and the content thereof is 48% by mass or more and 100% by mass with respect to carbon contained in the inkjet ink. % Or less. With such a configuration, even when the amount of alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce the decrease in printing resumability. Details of each component will be described below.

(carbon)
The carbon contained in the inkjet ink according to the present embodiment is not particularly limited. For example, medicinal charcoal, plant charcoal pigments such as Bincho charcoal or bamboo charcoal, orally ingestible carbon, or industrial petroleum Derived from carbon black. Among these carbons, those that can be taken orally are particularly preferable. In the case of using orally ingestible carbon, the ink-jet ink according to the present embodiment can be used for direct printing on the tablet surface, direct printing on foods, pharmaceuticals and packages that come into direct contact with foods.
In addition to the carbon as a black pigment, the ink-jet ink according to the present embodiment may have a dye that can be taken orally as appropriate in order to adjust the color of the ink. As a dye that can be taken orally, for example, a known synthetic food dye or natural food dye is appropriately selected and used as a food dye.

  Examples of synthetic edible dyes include tar dyes, natural dye derivatives, and natural synthetic dyes. Examples of the tar pigment include food red No. 2, 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. 1, Edible Blue No. 2, Edible Red No. 2 Aluminum Lake, Edible Red No. 3 Aluminum Lake, Edible Red No. 40 Aluminum Lake, Edible Yellow No. 4 Aluminum Lake, Edible No. 5 Aluminum Lake, Edible Blue No. 1 Aluminum Lake, Edible Blue No. 2 aluminum rake etc. are mentioned. Examples of natural pigment derivatives include norbixin potassium. Examples of natural synthetic pigments include β-carotene and riboflavin.

  Examples of natural edible pigments include anthocyanin pigments, carotenoid pigments, quinone pigments, flavonoid pigments, betaine pigments, monascus pigments, and other pigments originating from natural products. Examples of the anthocyanin pigment include red radish pigment, red cabbage pigment, red rice pigment, elderberry pigment, cowberry pigment, gooseberry pigment, cranberry pigment, salmon berry pigment, perilla pigment, Sim Blueberry pigment, strawberry pigment, dark sweet Cherry pigment, Cherry pigment, Hibiscus pigment, Hakulberry pigment, Grape juice pigment, Grape skin pigment, Black currant pigment, Blackberry pigment, Blueberry pigment, Plum pigment, White berry pigment, Boysenberry pigment, Mulberry pigment, Murasaki potato pigment , Purple corn pigment, purple potato pigment, raspberry pigment, red currant pigment, loganberry pigment, and other anthocyanin pigments. Examples of carotenoid pigments include Anato pigment, gardenia yellow, and other carotenoid pigments. Examples of quinone dyes include cochineal dyes, sicon dyes, rack dyes, and other quinone dyes. Examples of the flavonoid pigment include safflower yellow, cucumber pigment, onion pigment, and other flavonoid pigments. Examples of betaine dyes include beet red dyes. Examples of the Monascus pigment include Benikouji pigment and Benikouji yellow. Examples of other pigments derived from natural products include turmeric pigments, wedge pigments, gardenia red pigments, and spirulina blue pigments.

(solvent)
The inkjet ink according to the present embodiment includes a solvent for dispersing the above-described carbon. And the solvent contains the water as a main solvent, and the alcohol solvent as a dry solvent. Hereinafter, the main solvent and the dry solvent will be described.
-Main solvent The main solvent contained in the inkjet ink which concerns on this embodiment is water, for example, purified water. The “main solvent” means a component having the largest mass ratio in the entire solvent. The ratio of water as the main solvent contained in the inkjet ink according to this embodiment is, for example, 50% by mass or more of the entire inkjet ink.

-Dry solvent The dry solvent contained in the inkjet ink which concerns on this embodiment is an alcohol solvent, for example, is an alcohol solvent containing at least one of isopropyl alcohol (IPA) and normal propyl alcohol (NPA). The concentration of the alcohol solvent is 35 parts by mass or less with respect to the entire inkjet ink. When the concentration of the alcohol solvent exceeds 35 parts by mass with respect to the entire inkjet ink, the drying property of the ink becomes excessive, and the print resumability tends to be reduced. Further, the lower limit value of the concentration of the alcohol solvent is not particularly limited, but is, for example, 0.001 part by mass or more with respect to the entire inkjet ink. If it is in the said numerical range, the fall of printing resumability can be reduced.

(Dispersant)
The ink-jet ink according to this embodiment contains a dispersant in addition to the above-described carbon and solvent. The dispersant that can be added to the ink-jet ink according to the present embodiment is not limited as long as it can enhance the dispersibility of the carbon and has edible properties. For example, the HLB value is in the range of 11 or more and 20 or less. A sucrose fatty acid ester. The content of the sucrose fatty acid ester is in the range of 48% by mass to 100% by mass with respect to the aforementioned carbon. In addition, when the content of the sucrose fatty acid ester as a dispersant is less than 48% by mass with respect to the above-described carbon, the dispersion stability of the carbon tends to decrease. Moreover, when content of the sucrose fatty acid ester which is a dispersing agent exceeds 100 mass% with respect to the above-mentioned carbon, there exists a tendency for drying property to fall.

  The sucrose fatty acid ester contained in the inkjet ink according to the present embodiment has an HLB (Hydrophilic-Lipophilic Balance) value in the range of 11 or more and 20 or less. With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be reduced. In addition, when the HLB value of the sucrose fatty acid ester is less than 11, the print resumability tends to decrease. The upper limit of the HLB value of sucrose fatty acid ester is 20.

(Wetting agent)
The inkjet ink according to the present embodiment may contain a wetting agent in addition to the carbon, solvent, and dispersant described above, and the content thereof is 0.001 part by mass or more and 20 parts by mass or less with respect to the entire inkjet ink. It may be within the range. If it is such a structure, sufficient dryness can be provided when using it for an inkjet ink, and the fall of printing resumability can be reduced more. In addition, when the content of the wetting agent is less than 0.001 part by mass with respect to the entire inkjet ink, printing resumability tends to decrease. Moreover, when content of a wetting agent exceeds 20 mass parts with respect to the whole inkjet ink, it tends to become difficult to provide sufficient drying property to an inkjet ink.

Moreover, it is more preferable that the inkjet ink according to the present embodiment has a wetting agent content of 3 parts by mass or less with respect to the entire inkjet ink. With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced.
The wetting agent that can be added to the inkjet ink according to this embodiment is not particularly limited as long as it is generally added to the inkjet ink as a wetting agent. The wetting agent according to this embodiment is more effective if it has a high boiling point. Here, “high boiling point” means, for example, 140 ° C. or higher.

Specific examples of the wetting agent according to this embodiment include, for example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1, 4-diol, and 2-ethyl-1. 3-hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycol having a number average molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, glycerin, mesoerythritol, penta Examples include erythritol, 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-ethyl-2-pyrrolidone. Among these wetting agents, a wetting agent containing at least one of propylene glycol and glycerin is particularly preferable. With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced.
Moreover, the wetting agent which concerns on this embodiment may be used individually by 1 type, and may be used in combination of 2 or more type, for example.

(binder)
The ink-jet ink according to this embodiment may contain a binder in addition to the above-described carbon, solvent, dispersant, and wetting agent. The binder that can be added to the inkjet ink according to the present embodiment is not particularly limited as long as it is generally added to the inkjet ink as a binder, and includes, for example, a polysaccharide. Moreover, it is more preferable if the polysaccharide contained in the binder according to the present embodiment has a weight average molecular weight in the range of 1,000 to 10,000. With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced. If the weight average molecular weight of the polysaccharide as a binder is less than 1,000, it tends to be difficult to impart sufficient drying properties to the inkjet ink. Moreover, when the weight average molecular weight of the polysaccharide which is a binder exceeds 10,000, there exists a tendency for printing resumability to fall.

Moreover, it is preferable that content of the binder which concerns on this embodiment is 0.01 to 10 mass% of the mass of the whole inkjet ink. When the content of the binder is within the above range, the viscosity of the ink is such that ink jet printing can be suitably performed.
Examples of the binder according to this embodiment include maltodextrin, erythritol, PVP (polyvinylpyrrolidone), dextran, polydextrose, or starch substances such as corn and wheat, cellulosic substances such as carboxymethylcellulose and hydroxymethylcellulose, sodium alginate, Examples include polysaccharides such as arabic gum, locust bean gum, tranto gum, guar gum, and tamarind seeds.

[Printing method]
The inkjet ink according to the present embodiment is not particularly limited with respect to the printing method, and printing using an inkjet apparatus such as a commercially available inkjet printer is possible. For this reason, the inkjet ink which concerns on this embodiment has a wide application range, and is very useful. For example, the ink-jet ink according to the present embodiment can be printed by a so-called drop-on-demand ink-jet apparatus using a piezoelectric element (piezoelectric ceramic) as an actuator, or can be printed by another ink-jet apparatus.

  As a drop-on-demand ink jet apparatus, for example, an apparatus or actuator that employs a thermal ink jet system that discharges ink jet ink with water vapor pressure generated by instantaneously raising a minute heating element to a high temperature (200 to 300 ° C.), or an actuator An electrostatic type device that discharges ink-jet ink by electrostatically oscillating the ink, and a device that employs an ultrasonic method that utilizes an ultrasonic cavitation phenomenon. In addition, if the inkjet ink according to the present embodiment has a charging performance, it is possible to use an apparatus that employs a continuous ejection type (continuous type).

〔tablet〕
In the present embodiment, the inkjet ink according to the present embodiment may be printed and printed on the surface of a tablet, for example, using the printing method described above. Hereinafter, the structure of the tablet provided with the print image (printing part) printed with the inkjet ink which concerns on embodiment is demonstrated.
The tablet according to the present embodiment is a medical tablet, for example. Here, the “medical tablet” refers to, for example, a film coating in which a water-soluble surface layer is formed on the outermost surface of the tablet in addition to a plain tablet (naked tablet), sugar-coated tablet, enteric-coated tablet, orally disintegrating tablet, and the like. Includes tablets.

1A and 1B are a plan view showing a first configuration example of a medical tablet according to the present embodiment and a cross-sectional view of the plan view cut along X1-X′1. The medical tablets shown in FIGS. 1A and 1B are plain tablets, and an image 9 is printed on the surface of the base 1. The image 9 is an arbitrary image such as a character, a symbol, or a barcode, and is printed by the ink jet printing method using the ink jet ink described above.
2A and 2B are a plan view showing a second configuration example of the medical tablet according to the present embodiment and a cross-sectional view of the plan view cut along X2-X′2. The medical tablets shown in FIGS. 2A and 2B are film-coated tablets, and an image 9 is printed on the surface of the film 5 covering the base 1. The image 9 shown in FIGS. 2A and 2B is also printed by the inkjet printing method using the above-described inkjet ink, similarly to the image 9 shown in FIGS. 1A and 1B. is there.

  The active ingredient contained in the medical tablet is not particularly limited. For example, substances effective in the prevention and treatment of various diseases (eg sleep-inducing action, tranquilizer activity, antibacterial activity, antihypertensive action, anti-angina activity, analgesic action, anti-inflammatory activity, tranquilizing action, diabetes therapeutic activity, diuretic action Anticholinergic activity, anti-gastric hyperactivity, antiepileptic activity, ACE inhibitory activity, β-receptor antagonist or agonist activity, anesthetic activity, appetite suppression activity, antiarrhythmic activity, antidepressant activity, anticoagulant activity, antidiarrheal activity , Antihistaminic activity, antimalarial activity, antitumor activity, immunosuppressive activity, antiparkinsonism activity, antipsychotic activity, antiplatelet activity, antihyperlipidemic activity, etc.) Including, but not limited to, substances having a deodorizing action.

  The tablet which concerns on this embodiment can mix | blend the carrier accept | permitted on the use with an active ingredient as needed. For example, in the case of a medical tablet, a pharmaceutically acceptable carrier can be blended. As the pharmaceutically acceptable carrier, various organic or inorganic carrier substances commonly used as pharmaceutical materials are used. For example, excipients, lubricants, binders, disintegrants, thickeners and the like are appropriately mixed in appropriate amounts. . If necessary, additives such as preservatives, antioxidants, colorants, sweeteners and the like can be used.

  In the present embodiment, a medical tablet is described as an example of the tablet, but the present invention is not limited to this. The printing target of the inkjet ink according to the present embodiment is not particularly limited, and may be printed on the surface of various tablets such as food such as feed, fertilizer, cleaning agent, and ramune confectionery. In addition, the inkjet ink according to the present embodiment is not particularly limited with respect to the size to be printed, and can be applied to tablets of various sizes. Moreover, you may use the inkjet ink which concerns on this embodiment for the package which touches the direct printing to a foodstuff, a pharmaceutical, and a foodstuff directly besides the direct printing to the above-mentioned tablet surface.

  In addition, the medical tablet in the present embodiment is not particularly limited, but in particular, the effect tends to be high in a film-coated tablet having a surface coated with a film coat layer. This is because the ink is likely to remain on the tablet surface because the film-coated tablet has fewer voids on the printed tablet surface than the uncoated tablet. For this reason, if it is the inkjet ink which concerns on this embodiment, compared with the inkjet ink which concerns on a prior art, the effect of quick-drying will be exhibited easily.

(Effect of this embodiment)
(1) The ink-jet ink according to the present embodiment is an ink-jet ink containing water, an alcohol solvent, carbon, and a dispersant, and the alcohol solvent contains at least one of isopropyl alcohol and normal propyl alcohol, and alcohol. The concentration of the solvent is 35 parts by mass or less with respect to the entire inkjet ink, and the dispersant includes a sucrose fatty acid ester having an HLB value in the range of 11 to 20, and the content of the sucrose fatty acid ester is In the range of 48% by mass or more and 100% by mass or less with respect to carbon.
With such a configuration, even when the amount of alcohol solvent added to the carbon inkjet ink is increased to improve the drying property, it is possible to reduce a decrease in printing restartability as compared with the prior art. .

(2) In addition, the inkjet ink according to the present embodiment further includes a wetting agent, and the content of the wetting agent is in the range of 0.001 to 20 parts by mass with respect to the entire inkjet ink. Also good.
If it is such a structure, sufficient dryness can be provided when using it for an inkjet ink, and the fall of printing resumability can be reduced more.
(3) In addition, the content of the wetting agent included in the inkjet ink according to the present embodiment may be 3 parts by mass or less with respect to the entire inkjet ink.
With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced.

(4) The wetting agent contained in the inkjet ink according to the present embodiment may include at least one of propylene glycol and glycerin.
With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced.
(5) Moreover, the inkjet ink which concerns on this embodiment may further contain a binder, and the binder may contain polysaccharide.
With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced.

(6) Moreover, the weight average molecular weight of the polysaccharide contained in the inkjet ink which concerns on this embodiment may be in the range of 1,000 or more and less than 10,000.
With such a configuration, sufficient drying properties can be imparted to the ink-jet ink, and a decrease in resumption of printing can be further reduced.
(7) Moreover, the inkjet ink which concerns on this embodiment may be used for the direct printing on the tablet surface, the direct printing on foodstuffs, the package which touches a pharmaceutical and foodstuffs directly.
If it is such a structure, direct printing on the tablet surface and direct printing on food will be possible, and it will be possible to use it for packages that come into direct contact with pharmaceuticals and food.

(8) Moreover, the tablet according to the present embodiment includes a printed image printed with the above-described inkjet ink.
If it is such a structure, edible property can be provided also to the printed image part printed on the surface of a tablet.
(9) The tablet according to the present embodiment may be a medical tablet.
If it is such a structure, edible property can be provided also to the print image part printed on the surface of the medical tablet.

[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited at all by an Example.
(Manufacture of inkjet ink)
Hereinafter, the preparation procedure of the inkjet ink will be described.
The ink-jet ink contains each component of a pigment, an organic solvent, water, a dispersant, and other additives as necessary. As the order of preparation, first, water and an organic solvent were mixed to obtain a mixed solvent. Next, after adding a dispersing agent and a coloring material to the mixed solvent, other additives were added. Finally, this mixed solution was put into a disperser such as a paint shaker and finely dispersed for a specified time. Thus, an ink-jet ink according to this example was prepared. Hereinafter, various components will be specifically described.

Purified water (ion exchange water) was used as the water constituting the ink.
As the organic solvent, ethanol, 1-propanol, and 2-propanol were used as dry solvents.
Propylene glycol and glycerin were used as the wetting agent.
A sucrose fatty acid ester was used as the dispersant.
As the binder, maltodextrin or polydextrose was used.
The above ingredients were prepared as 21 different ink formulations. The composition is shown in Table 1.
In addition, the solid foreign material in a liquid was removed by letting each above-mentioned ink each pass a membrane filter. Specifically, a purified ink was obtained by allowing a membrane filter (cellulose acetate membrane) having a diameter of 5.0 μm to pass once, and subsequently passing once through a membrane filter (cellulose acetate membrane) having a diameter of 0.8 μm.

  The inkjet inks of Examples 1 to 14 and the inkjet inks of Comparative Examples 1 to 7 were produced by the above-described preparation method. In Table 1, each component of the inkjet ink of Examples 1-14 and the inkjet ink of Comparative Examples 1-7 is shown. Moreover, about each inkjet ink of Examples 1-14 and Comparative Examples 1-7, each evaluation of the dispersion stability of carbon, drying property, and printing resumability was performed. Table 1 shows the results of each evaluation. In addition, the evaluation method in a present Example is as follows.

(1) Evaluation of dispersion stability The inkjet inks of Examples 1 to 14 and Comparative Examples 1 to 7 were allowed to stand at 40 ° C. for 14 days, and the median diameter of carbon was measured. An increase in the median diameter means that the carbon particles are aggregated and means that the dispersion stability is low. The evaluation criteria are as follows.
○: No significant change in median diameter ×: Clearly increased particle diameter The above-mentioned “no significant change in median diameter” means that the median diameter immediately after ink preparation was 40 ° C. The increase in median diameter after standing for 14 days is 10 nm or less. Further, “obviously the particle diameter is increased” means that the increase width of the median diameter exceeds 10 nm.
The dispersion stability of each of Examples 1 to 14 was “◯”, whereas the dispersion stability of Comparative Examples 1 to 3 was “x”.

(2) Evaluation of drying property by transfer test The following two types of tablets 1 and 2 have a printing resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (conveying direction of a recording medium such as tablets), and a total number of nozzles of 2,656. Each of the images was printed with a print drop amount of 12 pl per drop using a piezoelectric ceramic driven drop-on-demand ink jet head.
・ Tablet 1 (film-coated tablet)
Tablet type / tablet 2 (non-printable tablet) with a coating layer formed by adding polyethylene glycol or titanium oxide pigment to hydroxypropylcellulose or hydroxypropylmethylcellulose on the surface of the tablet
Tablet type in which a coating layer is formed on the surface of a tablet by containing polyethylene glycol, titanium oxide pigment or the like in polyvinyl alcohol

Ten seconds after printing, the tablet attached to the digital force gauge was brought into contact with the printed tablet at a pressure of 2 to 3 N for 0.4 to 0.5 seconds, and it was confirmed whether or not the printed ink was transferred. . In Table 1, the density of the transferred ink was visually observed as a dryness evaluation result. The evaluation criteria are as follows.
◎: When there is no transfer of ink ○: When transfer of ink is very slight and visual confirmation is difficult △: When the color of the transferred ink is thin but can be easily visually confirmed ×: When the ink is transferred with dark color The drying properties of Examples 1 to 14 were all “◎” or “◯”, while the drying properties of Comparative Examples 4 to 5 were “x”.

(3) Evaluation of resumability of printing The inkjet head has a print resolution of 600 dpi in the main scanning direction, 600 dpi in the sub-scanning direction (conveying direction of a recording medium such as a tablet), and a piezoelectric ceramic drive drop-on-demand with a total number of 2,656 nozzles. A type inkjet head was used. The ink was left in the ink jet head without flushing for a specified time (30 to 120 minutes), and then a test pattern was printed with a print drop amount of 1 drop 6 pl using the ink jet head. Then, it was confirmed from the printing state of the test pattern whether or not ejection was possible from all nozzles without a non-ejection amount. In Table 1, as a result of evaluating the resumption of printing, the standing time during which ink can be ejected was measured. The evaluation criteria are as follows.
◎: 60 minutes or more and less than 120 minutes ○: 30 minutes or more and less than 60 minutes ×: Less than 30 minutes The printing restartability of each of Examples 1 to 14 is “◎” or “◯”, whereas Comparative Examples 6 to The print resumability of 7 was “x”.

  From the above results, an inkjet ink containing water, an alcohol solvent, carbon, and a dispersant, the alcohol solvent containing at least one of isopropyl alcohol and normal propyl alcohol, and the concentration of the alcohol solvent with respect to the entire inkjet ink. 35 parts by mass or less, and the dispersant contains a sucrose fatty acid ester having an HLB value in the range of 11 to 20, and the content of the sucrose fatty acid ester is 48% by mass to 100% by mass with respect to carbon. %, The decrease in printing resumability can be reduced as compared with the prior art even when the drying property is increased by increasing the amount of alcohol solvent added to the carbon inkjet ink. I understand that I can do it.

1 Base 5 Film 9 Image

Claims (9)

An inkjet ink comprising water, an alcohol solvent, carbon, and a dispersant,
The alcohol solvent includes at least one of isopropyl alcohol and normal propyl alcohol,
The content of the alcohol solvent is 35 parts by mass or less with respect to the entire inkjet ink,
The dispersant contains a sucrose fatty acid ester having an HLB value in the range of 11 or more and 20 or less,
The inkjet ink according to claim 1, wherein a content of the sucrose fatty acid ester is in a range of 48% by mass to 100% by mass with respect to the carbon. Further comprising a wetting agent;
2. The inkjet ink according to claim 1, wherein the content of the wetting agent is in the range of 0.001 to 20 parts by mass with respect to the entire inkjet ink.   The inkjet ink according to claim 2, wherein the content of the wetting agent is 3 parts by mass or less with respect to the entire inkjet ink.   The inkjet ink according to claim 2 or 3, wherein the wetting agent contains at least one of propylene glycol and glycerin. Further comprising a binder,
The inkjet ink according to any one of claims 1 to 4, wherein the binder contains a polysaccharide.   The inkjet ink according to claim 5, wherein the polysaccharide has a weight average molecular weight in a range of 1,000 or more and less than 10,000.   The ink-jet ink according to any one of claims 1 to 6, wherein the ink-jet ink is used for a direct printing on a tablet surface, a direct printing on a food, a package directly touching a pharmaceutical and a food.   The tablet provided with the printing part printed with the inkjet ink of any one of Claims 1-7.   The tablet according to claim 8, which is a medical tablet.

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