JP6345504B2 - Inkjet ink composition - Google Patents

Description

  The present invention relates to an inkjet ink composition.

  In order to prevent medical accidents such as dispensing errors and misuse, printing of tablet names and symbols on the surface of tablets has been performed. Conventionally, tablets are identified by a contact printing method such as engraving or transfer.

  However, in stamping, tableting troubles such as chipping or peeling of the tablet surface occur, and in transfer, the tablet collapses due to pressing with a transfer roll or the like, and further due to contact with the transfer roll or the like. There are problems such as contamination of tablets.

  Further, it is known that laser printing is performed as a non-contact printing method. However, laser printing requires that a discoloration-inducing oxide such as titanium oxide is contained in the tablet, and further, printing is performed. There is a problem that the color tone of characters is only an achromatic color such as black or gray.

  Further, in recent years, an inkjet printing method has attracted attention as a non-contact printing method. For example, Patent Document 1 discloses an edible inkjet ink composition that can be directly printed on a tablet having an orally disintegrating property. In this document, a synthetic dye aluminum lake (pigment) is used as a chromatic dye contained in the ink-jet ink composition. However, since a pigment is a finely powdered substance that is essentially insoluble in water, there is a problem in that a nozzle that ejects ink-jet ink tends to be clogged.

  In order to solve the problem of clogging of the nozzle for discharging the ink jet ink, it is conceivable to use a water-soluble dye instead of a pigment as a colorant to be blended in the ink jet ink composition. However, since the chromatic dye has low light resistance, there arises a new problem that characters printed on the tablet surface are faded or discolored.

JP2012-111824

  The present invention has been made in view of the above-described problems of an ink-jet ink containing a dye as a colorant. The main object of the present invention is to provide a highly light-resistant ink-jet ink composition containing a dye. There is.

  The inventor has conducted intensive research to solve the above-described problems. As a result, it has been found that blending a specific proportion of a polyvinyl polymer compound with an ink composition containing a dye suppresses discoloration / discoloration of the ink composition and greatly improves light resistance. The present inventor has completed the present invention by conducting further research based on such knowledge.

That is, the present invention typically provides the ink-jet ink composition described in the following section.
Item 1.
An inkjet ink composition comprising:
(A) a polyvinyl polymer compound, and (B) a dye,
The polyvinyl polymer compound is contained in an amount of 0.5 to 10% by mass based on the entire composition.
Inkjet ink composition.
Item 2.
The polyvinyl polymer compound is
(A1) polyvinyl alcohol and / or a derivative thereof;
General formula [1]
^{_{H 2 C = C (R 1}} ) -COOR 2 [1]
[Wherein, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ]
At least one polymerizable vinyl monomer represented by:
A copolymerized copolymer and (A2) at least one selected from the group consisting of polyvinylpyrrolidone,
Item 2. The inkjet ink composition according to Item 1.
Item 3.
The dye is a water-soluble tar pigment and / or a water-soluble natural pigment;
Item 3. The inkjet ink composition according to Item 1 or 2.
Item 4.
1 to 10 parts by mass of a polyvinyl polymer compound is contained with respect to 1 part by mass of the dye.
Item 4. The inkjet ink composition according to any one of Items 1 to 3.
Item 5.
Item 5. The inkjet ink composition according to any one of Items 1 to 4, which is edible.
Item 6.
Item 6. The ink-jet ink composition according to Item 5, which is for tablet or capsule printing.

  The ink-jet ink composition of the present invention is an ink-jet ink composition having high light resistance in which fading and discoloration are suppressed. Therefore, for example, when printing is performed on the surface of a tablet, capsule, or the like using the ink composition of the present invention, printed characters and the like can be stably retained for a long period of time.

  Furthermore, when printing on the tablet surface using the inkjet ink composition of the present invention, printing is preferably performed by an inkjet method without being limited to the difference in the state of the tablet surface such as uncoated tablets and coated tablets. it can.

The figure which shows the result of the fading / discoloration evaluation test of red ink. Note that “unirradiated” in FIG. 1 was irradiated with tablets not irradiated with fluorescent light, and “1.2 million lx · h” was irradiated with fluorescent light so that the integrated illuminance was 1.2 million lx · h. Each subsequent tablet is shown. The figure which shows the result of the fading / discoloration evaluation test of blue ink. Note that “unirradiated” in FIG. 2 was irradiated with tablets not irradiated with fluorescent light, and “1.2 million lx · h” was irradiated with fluorescent light so that the integrated illuminance was 1.2 million lx · h. Each subsequent tablet is shown. The figure which shows the result of the fading / discoloration evaluation test of green ink. Note that “unirradiated” in FIG. 3 was irradiated with tablets not irradiated with fluorescent light, and “1.2 million lx · h” was irradiated with fluorescent light so that the integrated illuminance was 1.2 million lx · h. Each subsequent tablet is shown.

  Hereinafter, the present invention will be described in detail.

  The inkjet ink composition of the present invention comprises (A) a polyvinyl polymer compound and (B) a dye.

  The (A) polyvinyl polymer compound contained in the inkjet ink composition of the present invention is a polymer compound having a polyvinyl skeleton. Examples of the polymer compound having a polyvinyl skeleton include polyvinyl alcohol, polyvinyl acetate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polymethyl methacrylate, polyacrylic acid, polyvinyl pyrrolidone, carboxyvinyl polymer, polyvinyl acetal, polychlorinated. Examples thereof include polymer compounds such as vinylidene and derivatives thereof, and polymer compounds including polymer compounds having these polyvinyl skeletons as polymerizations or copolymers. For example, as a polymer compound containing polyvinyl alcohol as a copolymer, a polyvinyl alcohol copolymer (A1) described later can be mentioned.

  Among these, as the polyvinyl polymer compound contained in the ink-jet ink composition of the present invention, at least one polymer selected from the group consisting of a polyvinyl alcohol copolymer (A1) and (A2) polyvinyl pyrrolidone described later is used. A compound is preferred.

  Moreover, the inkjet ink composition of the present invention contains about 0.5 to 10% by mass of the polyvinyl polymer compound, preferably about 1 to 9% by mass, and about 2 to 8% by mass with respect to the entire composition. More preferably. When the content of the polyvinyl polymer relative to the entire composition is within the above range, the light resistance of the ink composition can be improved. Furthermore, when the content of the polyvinyl polymer in the entire composition is within the above range, the viscosity of the ink composition is such that ink can be ejected by the ink jet method. It can be suitably used as an ink.

The polyvinyl alcohol copolymer (A1) in the inkjet ink composition of the present invention comprises polyvinyl alcohol and / or a derivative thereof,
General formula [1]
^{_{H 2 C = C (R 1}} ) -COOR 2 [1]
[Wherein, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. ] A copolymer obtained by copolymerizing at least one polymerizable vinyl monomer represented by the formula (hereinafter referred to as “PVA copolymer”).

  The kind of polyvinyl alcohol (hereinafter referred to as “PVA”) that is a raw material for the PVA copolymer is not particularly limited, and for example, a completely saponified product, an intermediate saponified product, or a partially saponified product can be used. As the PVA derivatives, various modified PVAs such as amine-modified PVA, ethylene-modified PVA, and terminal thiol-modified PVA can be used.

PVA can be obtained by radical polymerization of vinyl acetate and appropriately saponifying the obtained polyvinyl acetate. Therefore, usually, PVA has a —OCOCH ₃ group derived from vinyl acetate. PVA can be classified into complete saponification products, intermediate saponification products, and partial saponification products, depending on the degree of saponification. The saponification degree of the PVA used in the present invention is preferably about 70 mol% or more, more preferably about 80 mol% or more, and further preferably about 85 mol% or more. Among them, a PVA saponified product having a saponification degree of about 85 to 90 mol%, particularly about 86 to 89 mol% is preferable. As is well known in the art, a completely saponified product of PVA usually means a PVA having a saponification degree of about 98 mol% or more, and the saponification degree is not necessarily 100 mol%. It does not mean PVA.

  In addition, various modified PVAs such as amine-modified PVA, ethylene-modified PVA, and terminal thiol PVA exemplified as PVA derivatives can be produced by, for example, methods known in the art.

  In addition, PVA and its derivative can also purchase and use a commercial item. For example, it can be purchased from Nippon Synthetic Chemical Industry Co., Ltd., Nippon Vinegar-Poval Co., Ltd.

  PVA and its derivatives are known in various degrees of polymerization, but the average degree of polymerization is not particularly limited. For example, those having an average degree of polymerization of about 200 to 5000, preferably about 300 to 3800, more preferably about 300 to 3000 can be used. The average degree of polymerization of PVA and its derivatives can be determined by GPC (Gel permeation Chromatography) method.

  PVA and its derivative can be used individually by 1 type or in combination of 2 or more types. For example, PVA and various modified PVAs having different saponification degrees can be used alone or in combination of two or more.

The polymerizable vinyl monomer used as the raw material for the PVA copolymer is
General formula [1]
^{_{H 2 C = C (R 1}} ) -COOR 2 [1]
[Wherein, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. It is a compound represented by this.

  Specific examples of the polymerizable vinyl monomer represented by the general formula [1] include acrylic acid, methacrylic acid, methyl methacrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, isobutyl methacrylate, and isobutyl acrylate. Can be mentioned. Moreover, these salts may be sufficient as acrylic acid and methacrylic acid. For example, these sodium salts, potassium salts, ammonium salts, or alkylamine salts may be used. These polymerizable vinyl monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  When two or more kinds of polymerizable vinyl monomers are used in combination, at least one of acrylic acid and methacrylic acid (or a salt thereof), methyl methacrylate, methyl acrylate, and ethyl methacrylate , Ethyl acrylate, butyl methacrylate, butyl acrylate, isobutyl methacrylate, and at least one selected from the group consisting of isobutyl acrylate are more preferably used in combination, and acrylic acid or methacrylic acid and methyl methacrylate are used in combination. More preferably.

  The ratio of PVA and / or its derivative and the polymerizable vinyl monomer in the PVA copolymer is not particularly limited, but 20 to 95% by mass of PVA and / or its derivative and 5 of the polymerizable vinyl monomer are present. It is preferable to set it as -80 mass%, It is more preferable that PVA and / or its derivative (s) are 50-90 mass%, and a polymerizable vinyl monomer is 10-50 mass%.

  In addition, when two or more kinds of polymerizable vinyl monomers are used in combination, the ratio of the combination is not particularly limited. (I) Acrylic acid, methacrylic acid, their sodium salts, potassium salts, ammonium salts, and alkyls At least one selected from the group consisting of amine salts and (II) at least one selected from the group consisting of methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, isobutyl methacrylate, and isobutyl acrylate When seeds are used in combination, the mass ratio of (I) is preferably 5 to 50% by mass and preferably 10 to 40% by mass with respect to the total mass of the polymerizable vinyl monomer. More preferably, the mass ratio of (II) is 5 to 95% by mass. It is preferable to, and more preferably 60 to 90 mass%.

  A method of copolymerizing PVA and / or a derivative thereof and a polymerizable vinyl monomer can be performed by a known method. For example, PVA and / or a derivative thereof are added to water, heated and dissolved, and then at least one polymerizable vinyl monomer and a polymerization initiator are added and copolymerized to be copolymerized. Can be obtained. More specifically, after PVA and / or its derivative are dispersed in ion-exchanged water and completely dissolved at 90 to 100 ° C., at least one polymerizable vinyl monomer is added, and nitrogen substitution is performed. An initiator is added and allowed to react for about 2 to 5 hours to obtain a PVA copolymer. PVA and / or its derivatives added to water. The mass ratio of the polymerizable vinyl monomer determines the mass ratio of the PVA and / or derivative thereof and the polymerizable vinyl monomer in the PVA copolymer. Therefore, PVA and / or its derivatives added to water. In addition, the mass ratio of the polymerizable vinyl monomer is preferably about the same as the mass ratio of the PVA and / or derivative thereof and the polymerizable vinyl monomer in the PVA copolymer.

  As the polymerization initiator, those conventionally used can be used. For example, azo compounds such as 2,2′-azobis (2-aminopropane) hydrochloride, AIBN (azoisobutyronitrile), persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, t-butyl hydro Organic peroxides such as peroxides, redox initiators such as hydrogen peroxide-tartaric acid and hydrogen peroxide-sodium tartrate can be used.

Although not intended to be limited to interpretation, in the present invention, the reaction mechanism when copolymerizing PVA and / or a derivative thereof and a polymerizable vinyl monomer is generally as follows. it is conceivable that. That is, first, hydrogen of the methyl group at the terminal of the -OCOCH ₃ group present in PVA is extracted by the polymerization initiator, and a radical is generated. Next, a polymerizable vinyl monomer is bonded to the radical, the double bond of the polymerizable vinyl monomer is cut, and a radical is generated again. Thereafter, a polymerizable vinyl monomer is further bonded to the radical, and the same reaction is repeated.

In the present invention, the PVA copolymer has a structure in which at least one polymerizable vinyl monomer described above is graft-polymerized to -OCOCH ₃ group existing as a side chain of PVA. In this graft polymerization, PVA may be bonded to each other through a polymer obtained by polymerization or copolymerization of at least one polymerizable vinyl monomer. In other words, in the present invention, the PVA copolymer may have a structure in which at least one polymerizable vinyl monomer is polymerized to crosslink PVA.

For example, when acrylic acid and methyl methacrylate are used as the polymerizable vinyl monomer, the PVA copolymer is a copolymer of acrylic acid and methyl methacrylate bonded to PVA via the -OCOCH ₃ group of PVA. You may have the structure.

  Specific examples of such a PVA copolymer (PVA / acrylic acid / methyl methacrylate copolymer) include POVACOAT (registered trademark) type F, type R, type MP (all manufactured by Daido Kasei Kogyo Co., Ltd.) and the like. Can be mentioned.

  The (A2) polyvinylpyrrolidone (hereinafter referred to as “PVP”) in the ink-jet ink composition of the present invention may be obtained by polymerizing vinylpyrrolidone. The quality defined as “Povidone” is preferred.

  In addition, PVP can also purchase and use a commercial item. For example, it can be purchased from ISP TECHNOLOGIES.

  The type of the (B) dye contained in the inkjet ink composition of the present invention is not particularly limited as long as it is a water-soluble pigment that can be used in pharmaceuticals, foods, and the like. For example, Red No. 2, Red 3 No. 102, Red No. 102, Red No. 104, Red No. 105, Red No. 106, Yellow No. 4, Yellow No. 5, Green No. 3, Blue No. 1, Blue No. 2, etc .; Water-soluble natural pigments such as safflower, purple, cochineal and the like can be mentioned.

  The ratio of the dye contained in the inkjet ink composition of the present invention is not particularly limited, and for example, it is preferably about 1 to 5 parts by mass with respect to the total amount of the composition.

  In the technical field to which the present invention belongs, “pigments” and “dyes” are clearly distinguished. “Pigment” means a pigment that is insoluble in water. For example, a pigment obtained by lacquering (insolubilizing) the above water-soluble tar pigment with aluminum, barium, zirconium, etc., yellow ferric oxide, red ferric oxide, oxidized Examples include inorganic pigments such as titanium. On the other hand, “dye” means a water-soluble pigment as described above.

  Moreover, in the inkjet ink composition of this invention, it is preferable that (A) polyvinyl polymer compound is included about 1-10 mass parts with respect to 1 mass part of (B) dye, and about 1-5 mass parts is included. Is more preferable.

  Moreover, the inkjet ink composition of this invention may contain components other than the above-mentioned as needed.

  For example, in order to improve the drying property of the ink, part of the water can be replaced with alcohols such as ethyl alcohol and butyl alcohol as necessary.

  For example, in addition to the component (A), an edible water-soluble polymer may be blended. Examples of the edible water-soluble polymer include shellac, cellulosic polymer, crystalline cellulose, gelatin, casein, soy protein, and dextrin.

  Furthermore, you may mix | blend a pH adjuster and a electrically conductive agent as needed. Although the kind of pH adjuster is not specifically limited, It is a food additive and is preferably a component that volatilizes after printing. Moreover, it is preferable that a electrically conductive agent is approved as a food additive, for example, sodium lactate, sodium acetate, etc. are mentioned.

  The ink-jet ink composition of the present invention contains a dye that is likely to undergo discoloration and fading compared to a pigment, but as described above, by blending a polyvinyl polymer compound at a specific ratio, Light resistance can be significantly improved. In other words, the ink-jet ink composition of the present invention is an ink-jet ink composition in which fading / discoloration is suppressed or an ink-jet ink composition with improved light resistance.

  Further, the ink composition containing a pigment has a relatively high viscosity because the pigment itself is a fine powder and a large amount of a dispersant needs to be blended. For this reason, when printing is performed by the inkjet method, there is a high possibility that the nozzles of the printer are clogged. If the viscosity is adjusted to be low in order to prevent clogging of the nozzles, there is a problem that the stability of the ink itself is lost. Thus, it is known that it is extremely difficult to prepare an inkjet ink containing a pigment. On the other hand, since the ink-jet ink composition of the present invention contains a water-soluble dye instead of a pigment as a pigment component, problems such as nozzle clogging as in the case of using a pigment do not occur. It can be suitably used as an ink used in an inkjet method.

  Furthermore, since the components (A) and (B) contained in the inkjet ink composition of the present invention are both edible components, the inkjet ink composition of the present invention can be used for pharmaceuticals, health foods, It can be suitably used as an ink composition for printing on the surface of food orally ingested, in other words, an ink composition for ingestion, an edible ink composition, or an edible ink composition. Is.

  Furthermore, the ink-jet ink composition of the present invention can be suitably printed regardless of the difference in the state of the tablet surface, such as ordinary bare tablets and coated tablets. Moreover, it can print suitably also on formulation surfaces other than a tablet, such as a capsule surface and a film surface. That is, the ink-jet ink composition of the present invention can be suitably printed regardless of the properties of the printing surface. In particular, as an ink-jet ink composition for tablets or capsules, more specifically, It can be suitably used as an inkjet ink composition for capsule printing.

  The manufacturing method of the inkjet ink composition of the present invention is not particularly limited and can be manufactured by a known method. For example, an inkjet ink composition can be prepared by dissolving a polyvinyl polymer compound and a dye in water. In this case, the blending amount and / or blending ratio of the polyvinyl polymer compound and the dye is preferably adjusted as appropriate so as to be within the above-described range.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to the following example.

Test Example 1: Discoloration / fading evaluation test of red ink Water-soluble polymer compounds and dyes listed in Table 1 below were dissolved in purified water to prepare red inks of Examples 1 to 3 and Comparative Examples 2 and 3. did. Further, as a red ink not containing a water-soluble polymer compound, the dyes shown in Table 1 below were dissolved in purified water to prepare a red ink of Comparative Example 1. The prepared red inks of Examples 1 to 3 and Comparative Examples 1 to 3 have a viscosity that can be discharged from the nozzles of an inkjet printer (viscosity at 25 ° C. is about 2 to 15 mPa · s).

The water-soluble polymer compounds used in Examples 1 to 3 and Comparative Examples 2 and 3 are as follows.
-Examples 1 and 3: PVA copolymer-Example 2: PVP [PVP K25; manufactured by Wako Pure Chemical Industries, Ltd.]
Comparative Example 2: Dextrin hydrate (Wako Pure Chemical Industries, Ltd.)
Comparative Example 3: Hydroxypropylmethylcellulose (hereinafter referred to as “HPMC”) [TC-5E; manufactured by Shin-Etsu Chemical Co., Ltd.]

  In addition, the PVA copolymer used in Examples 1 and 3 was obtained by the following method. A separable flask equipped with a cooling reflux tube, a dropping funnel, a thermometer, a nitrogen introduction tube, and a stirrer was equipped with PVA (variety JP05, average polymerization degree 500, saponification degree 88%; manufactured by Nihon Vineyard Poval Co., Ltd.) 175.8 g and ion exchange water 582.3 g were charged and dispersed at room temperature, and then completely dissolved at 95 ° C. Next, 5.4 g of acrylic acid and 37.3 g of methyl methacrylate were added, the temperature was raised to 50 ° C. after nitrogen substitution, 8.5 g of tertiary butyl hydroperoxide and 8.5 g of sodium erythorbate were added, and 4 hours. Then, the reaction was terminated to obtain a PVA copolymer. This was dried and pulverized to obtain a PVA copolymer powder.

  Next, the letter “R” was drawn on the surfaces of the HPMC-coated tablet and the bare tablet using the red ink of Examples 1 to 3 and Comparative Examples 1 to 3 using a brush. Thereafter, each tablet was irradiated with light from a fluorescent lamp with an illuminance of 3300 lx for about 15 days so as to have an integrated illuminance of 1,200,000 lx · h, and the degree of fading and discoloration of the letters drawn on the surface of each tablet was confirmed by visual observation.

The results of Test Example 1 are shown in the “degree of discoloration / fading” column of Table 1 and FIG. In addition, in the “degree of discoloration / fading” column of Table 1, the results of Test Example 1 are expressed using the following four-stage evaluation criteria.
◎: Almost no fading or discoloration was confirmed. ○: Slight fading or discoloration was confirmed. △: Clear fading or discoloration was confirmed. ×: Fading to the extent that characters disappeared was confirmed.

  As is apparent from Table 1 and FIG. 1, the red ink composition (Examples 1 to 3) containing PVA copolymer or PVP as a water-soluble polymer compound is a red ink composition not containing a water-soluble polymer compound. It was confirmed that the degree of fading and discoloration of the ink was small as compared with the red ink composition (Comparative Examples 2 and 3) containing the product (Comparative Example 1) and other water-soluble polymer compounds.

  Further, when the red ink composition (Example 1) containing 5% by mass of the PVA copolymer and the red ink composition (Example 3) containing 1% by mass were compared, the red ink composition of Example 1 was compared. It was confirmed that the degree of fading and discoloration of the ink was smaller.

Test Example 2: Blue ink discoloration / fading evaluation test Each component shown in Table 2 below was dissolved in purified water to prepare blue inks of Examples 4 and 5 and Comparative Examples 4 and 5. In addition, the PVA copolymer in Example 4, PVP in Example 5, dextrin hydrate in Comparative Example 4, and HPMC in Comparative Example 5 were all the same as those in Test Example 1. In addition, the prepared blue inks of Examples 4 and 5 and Comparative Examples 4 and 5 all have a viscosity that can be ejected from the nozzles of an inkjet printer (viscosity at 25 ° C. is about 2 to 15 mPa · s). .

  Next, in the same manner as in Test Example 1, the letters “B” were drawn on the surfaces of the HPMC-coated tablets and the bare tablets using a blue ink of Examples 4 and 5 and Comparative Examples 4 and 5. . Thereafter, each tablet was irradiated with light from a fluorescent lamp with an illuminance of 3300 lx for about 15 days so as to have an integrated illuminance of 1,200,000 lx · h, and the degree of fading and discoloration of the letters drawn on the tablet surface was confirmed visually.

  The results of Test Example 2 are shown in the “degree of discoloration / fading” column of Table 2 and FIG. In the “degree of discoloration / fading” column of Table 2, the results of Test Example 2 are represented in the same manner as in Table 1 and the degree of discoloration / fading is expressed using four evaluation criteria.

  As is clear from the results of Table 2 and FIG. 2, the blue ink composition (Examples 4 to 6) containing PVA copolymer or PVP as the water-soluble polymer compound was blended with other water-soluble polymer compounds. It was confirmed that the degree of fading and discoloration of the ink was small compared to the blue ink composition (Comparative Examples 4 and 5).

  Further, when the blue ink composition containing 5% by mass of the PVA copolymer (Example 4) and the blue ink composition containing 1% by mass (Example 6) were compared, the blue ink composition of Example 4 was compared. It was confirmed that the degree of fading and discoloration of the ink was smaller.

Test Example 3: Discoloration / Fade Evaluation Test of Green Ink Each component described in Table 3 below was dissolved in purified water to prepare blue inks of Examples 6 and 7 and Comparative Examples 6 and 7. In addition, the PVA copolymer in Example 6, PVP in Example 7, dextrin hydrate in Comparative Example 6, and HPMC in Comparative Example 7 were all the same as in Test Examples 1 and 2. In addition, the prepared blue inks of Examples 6 and 7 and Comparative Examples 6 and 7 all have a viscosity that can be ejected from the nozzles of an inkjet printer (viscosity at 25 ° C. is about 2 to 15 mPa · s). .

  Next, in the same manner as in Test Examples 1 and 2, “G3” characters were drawn on the surfaces of the HPMC-coated tablets and the bare tablets using a brush with the green inks of Examples 6 and 7 and Comparative Examples 6 and 7. It was. Thereafter, each tablet was irradiated with light from a fluorescent lamp with an illuminance of 3300 lx for about 15 days so as to have an integrated illuminance of 1,200,000 lx · h, and the degree of fading and discoloration of the letters drawn on the tablet surface was confirmed visually.

  The results of Test Example 3 are shown in the “degree of discoloration / fading” column of Table 3 and FIG. In the “degree of discoloration / fading” column of Table 3, the results of Test Example 3 are represented using four-level evaluation criteria in the same manner as in Tables 1 and 2.

  As is clear from the results in Table 3 and FIG. 3, the green ink composition (Examples 7 and 8) containing PVA copolymer or PVP as the water-soluble polymer compound was blended with other water-soluble polymer compounds. It was confirmed that the degree of fading and discoloration of the ink was small compared to the green ink composition (Comparative Examples 6 and 7).

  From the results of the above Test Examples 1 to 3, when a water-soluble polymer compound to be blended in the ink composition is a polyvinyl polymer compound such as a PVA copolymer or PVP, other water-soluble polymer is used. As compared with the case of using the compound, it was found that the fading and discoloration of the ink can be suppressed, and the light resistance of the ink composition is greatly improved.

  Furthermore, since the ink composition containing the polyvinyl polymer compound showed good results in both coated tablets and bare tablets, the ink-jet ink composition of the present invention is suitable regardless of the properties of the printing surface. It was found that it can be used.

Claims (7)

An inkjet ink composition comprising:
(A) a copolymer obtained by copolymerizing polyvinyl alcohol, acrylic acid, and methyl methacrylate, and (B) a dye,
The copolymer is contained in an amount of 0.5 to 10% by mass based on the entire composition.
Inkjet ink composition. In the copolymer of (A), the ratio of polyvinyl alcohol, acrylic acid and methyl methacrylate is 10 to 50% by mass with respect to polyvinyl alcohol 50 to 90% by mass,
The inkjet ink composition according to claim 1. In the copolymer (A), the ratio of acrylic acid to methyl methacrylate is
Acrylic acid is 10 to 40% by mass and methyl methacrylate is 60 to 90% by mass with respect to the total mass of acrylic acid and methyl methacrylate.
The inkjet ink composition according to claim 1 or 2. The dye is a water-soluble tar pigment and / or a water-soluble natural pigment;
The inkjet ink composition according to claim 1 . 1 to 10 parts by mass of a polyvinyl polymer compound is contained with respect to 1 part by mass of the dye.
The inkjet ink composition in any one of Claims 1-4 . The inkjet ink composition according to any one of claims 1 to 5 , which is edible. The inkjet ink composition according to claim 6 , which is for tablet or capsule printing.