JP2006188604A - Ink composition for ink-jet printing and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition for ink-jet printing having excellent storage characteristics such as dispersion stability of a pigment or jetting stability of an ink, printing characteristics such as quick-drying properties and water resistance of prints and various excellent long-term environmental durabilities of the prints in a water-based pigment jet ink. <P>SOLUTION: A water-based pigment liquid composition is characterized as follows. The composition consists essentially of three of (1) a pigment selected from the group consisting of carbon black and an organic pigment, (2) an aqueous dispersion medium and (3) one or more kinds of dispersing agents selected from the group of N-(sulfoxyphenyl)-3-hydroxy-2-naphthalenecarboxamides represented by general formula (1) and having specific substituents. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aqueous pigment ink, and more particularly to an ink composition for ink jet printing in which a pigment coated with a vinyl polymer is dispersed in an aqueous medium as a colorant.

  As a colorant for ink for inkjet printing (hereinafter abbreviated as jet ink), there has been a proposal for a long time to use a pigment that is superior to the reliability of recorded matter such as water resistance and light resistance as compared with dyes. Furthermore, in order not to pollute the use environment, there has also been a proposal for an ink in which a colorant pigment is dispersed in an aqueous medium. That is, an aqueous pigment ink is desirable. From the viewpoint of the mechanism of the ink jet printing apparatus and fine printing, the pigment needs to be dispersed as fine particles. Since pigments are difficult to disperse in an aqueous medium, attempts have been made to disperse selectively using a water-soluble surfactant or resin that is compatible with the pigment. For example, JP-A-47-30407 discloses polyoxyethylene ether sulfate and poly-2-vinylpyridine, JP-A-50-49003 discloses polyoxyethylene glycol having a molecular weight of 1000 to 10,000, and JP-A-56-147863. Proposed that a polymer having both a hydrophilic structure portion and a hydrophobic structure portion, specifically, for example, a water-soluble salt of a styrene-maleic acid copolymer, is effective for dispersing the pigment in an aqueous medium. Although the technique for dispersing pigments in an aqueous medium has progressed in this way, the required properties of jet ink have become more sophisticated as ink jet printing has become widespread. It is difficult to keep stable. Among these dispersants, some soluble resin dispersants are not perfect but exhibit relatively good dispersion stability. However, as the ink is dried on the surface of the discharge nozzle, the ink is concentrated and thickened, the discharge of the ink and the flight path of the ink droplet become unstable, and finally the nozzle becomes clogged and does not discharge. This was the fate of using a soluble resin dispersant. A method for ensuring the dispersion stability of fine pigments without using a soluble resin dispersant is awaited.

  Since dispersion of the pigment directly in the medium has the above-mentioned difficulties, it has been proposed to ensure dispersibility as resin particles in which the pigment is coated with a resin. That is to apply the stable dispersion technology of resin emulsion and latex. For example, in JP-A-53-94581, carbon black is dispersed in a hydrophobic vinyl monomer and polymerized by heating to coat the carbon black with a hydrophobic polymer, thereby improving the dispersibility of the carbon black in a non-aqueous medium. A method is disclosed. However, there is no specific description or suggestion regarding the selection of a vinyl monomer for improving dispersibility in an aqueous medium. Japanese Patent Laid-Open No. 54-146109 discloses a jet ink in which water-insoluble vinyl polymer particles containing a hydrophobic dye solution are dispersed in an aqueous medium, and as a method for realizing this, dissolves in a solvent that is substantially immiscible with water. Discloses a method in which the hydrophobic dye solution is mixed with an aqueous dispersion of water-insoluble vinyl polymer particles, and the hydrophobic dye solution is transferred and impregnated into the vinyl polymer particles. In the specification of the application, a pigment is shown as a hydrophobic dye. However, in the color material field, the pigment is defined as having no solvent capable of dissolving the pigment, so that the pigment is distinguished from the dye. The application technique does not hold in the case of pigments. In fact, only the word “pigment” is described, and there is no specific description in the case of a pigment. A similar application is filed in Japanese Patent Application Laid-Open No. 58-2366 regarding the media specification, and in Japanese Patent Application Laid-Open No. 58-45272 the polymer particles are made of polyurethane, but there is no specific description in the case of pigments. This is the same as Kaisho 54-146109. Japanese Patent Application Laid-Open No. 59-120667 discloses an aqueous pigment ink comprising a water-dispersible processed pigment, a water-soluble resin, a water-soluble organic solvent and water. A water-dispersible processed pigment is a pigment whose surface is coated with a water-dispersible resin, that is, an emulsion resin. There is no particular limitation on the type or composition of the pigment or emulsion resin, and the pigment and the resin emulsion become primary particles. It is said that it is obtained by kneading strongly so that the emulsion particles are broken. The water-soluble resin is a binder / dispersant, and there is no particular limitation on the type or composition thereof. Although the water-based pigment ink of the application uses a resin-coated pigment, it contains a water-soluble resin, so it cannot escape from the difficulties described in the previous section.

  JP-A-9-272831 discloses a method of grafting a polymer to a pigment, JP-A-11-293165 discloses a method of fixing a water-soluble resin with a coupling agent, and JP-A 2000-95987 discloses a method of vinyl. Although a method of modifying with a polymer has been disclosed, it is inferior in coloring power because it is not sufficiently stabilized with a sufficiently fine particle size and the pigment content is small.

  In order to overcome the drawbacks of the microencapsulation methods such as the particle size in conventional methods such as emulsion polymerization and suspension polymerization and the low pigment concentration in the capsules, JP-A-3-221137 and JP-A-9-151342. In Japanese Patent Application Laid-Open No. 9-217019, Japanese Patent Application Laid-Open No. 11-209672, etc., a pigment is dispersed together with an anionic organic polymer compound to adsorb the resin on the pigment surface, and then the resin is insolubilized by an acid and fixed on the pigment surface. However, it has not been possible to obtain sufficient dispersion stability with the pigment still in the ultrafine particle state, and a further sense of density is required.

  Summarizing the above, although there is a long-awaited development of an aqueous pigment-based jet ink in which fine pigment particles are stably dispersed without using a soluble resin dispersant as a jet ink, an ink that is still satisfactory Is not realized. As a result of intensive studies to overcome this state, the present inventors used a surfactant to coat pigment monomers dispersed in an aqueous medium with a vinyl monomer. By mixing the monomer, that is, an aqueous emulsion of the monomer represented by the formula (Chemical Formula 3) in the present specification with an aqueous pigment dispersion in the presence of a persulfate, the monomer is limited to be an acrylic resin. When the monomer is converted to a state in which the pigment particles are coated and then heated to polymerize the monomer, all of the pigment particles in the aqueous medium are coated with the acrylic resin and are dissolved in the medium. It has been found that a pigment dispersion with no minute can be obtained. The coated pigment particles in the dispersion are kept in a dispersed state by the action of the surfactant contained in the above-described surfactant or monomer aqueous emulsion. This patent application was filed as Japanese Patent Application No. 2003-285673 (2003.8.4). This selective invention has realized a significant advance over the prior art.

  However, after repeated practical printing tests with different ink jet printers and paper, the ink penetration rate into paper (quick drying), ink drying and solidification on the nozzle surface (dischargeability), and water resistance of printed matter It has been found that there is a case where the dilemma that the long-term stability of the pigment dispersion in the ink becomes insufficient when the printability such as the property is enhanced is insufficient. In order to overcome such difficulties and increase the versatility when used as jet ink, in addition to the specific acrylic monomer represented by the formula (3), it is represented by the formula (4) in the present specification. The inventors have found that it is effective to copolymerize a specific fluorine-containing acrylic monomer and has filed a patent application separately.

Although the performance of the water-based pigment jet ink has been improved by the invention described in the preceding paragraph and the preceding paragraph, as a result of further investigation, the surfactant used there may reduce the durability of the printed matter. It has been found. That is, when the printed material is exposed to an environmental condition such as oxygen, water, light, especially ultraviolet light for a long period of time, the color density of the printed material and the mechanical strength of the printing paper gradually decrease. Although details are unknown, it is almost certain that the presence of the surfactant in the printed matter itself and the oxidative degradation product of the polyoxyalkylene chain which is a component thereof have an adverse effect on the pigment and the printed paper. The durability of the pigment to the dye is diminished. Substances with polyoxyalkylene chains are used as humectants and penetrants, which are constituents of jet ink, due to the demands of ink printability, but these also have the potential to reduce the durability of printed materials like surfactants. There is. In any case, since it is recognized that the above-mentioned adverse effects are reduced when the amount of the surfactant used is small, a measure for reducing the amount of the surfactant, particularly the polyoxyalkylene chain-containing surfactant is required.

  In dispersing a pigment in an aqueous medium, an attempt has been made to suggest the possibility of reducing the amount of surfactant or water-soluble polymer used as a dispersant. In the case of using not only a pigment but also a dye having insufficient solubility as a colorant, for example, in JP-A Nos. 55-145773 and 55-1551070, an aromatic ring having a sodium sulfonate group as an essential substituent It is proposed that the diazo compound is added to an ink jet recording liquid to ensure the stability of the dissolution or dispersion of a dye or pigment as a colorant. JP-A-55-144064 proposes that a recording liquid using a water-soluble dye is mixed with a phthalocyanine compound having a sodium sulfonate group as an essential substituent. All of the above are proposals for ensuring the stability of the dissolution or dispersion of the dye or pigment by blending a compound having a molecular skeleton structure similar to that of the dye or pigment and also having a sodium sulfonate group. If these compounding agents have a preferable function as a dispersant, it is expected that the amount of surfactant or water-soluble polymer used can be reduced. However, since these compounding agents have a sodium sulfonate group and are readily soluble in water, the difficulty in water resistance of the finished product has not been solved.

On the other hand, in the Color Material Association Journal 73 (2001), p165, when dispersing an anthraquinone yellow pigment in an organic solvent, a polar polymer soluble in the same solvent is used as a dispersing agent, and further, It has been reported that when a sulfonated pigment is used in combination, finer dispersion of the pigment is realized as compared with the case of using only the dispersant. That is, a compound having the same skeleton structure as the pigment contributes to fine dispersion of the pigment as a dispersion aid. However, in such a case, the dispersion aid itself is also a colorant. Therefore, in order to avoid color turbidity, the dispersion aid is different for each pigment to be used, and the use is limited to specific cases and is versatile. It is scarce. Moreover, it is unlikely that the function as a dispersant, particularly a dispersant in an aqueous pigment solution composition, can be exhibited with only such a dispersion aid. Further, in this case, since the soluble polymer dispersant is used as an essential component, it is unavoidable from the difficulty of nozzle clogging as described above.

  As a result of searching for substances having a lot in common with the pigment and the molecular structure, that is, a wide variety of substances having a benzene ring or a naphthalene ring, the present inventors searched for possible dispersion agents in aqueous pigment liquid compositions. We have found that this is possible with derivatives of oxynaphthoic acid, in particular 3-oxy-2-naphthalenecarboxylic acid. Among them, a carboxylic acid amide compound with a specific aniline derivative having a sulfonic acid group as a substituent is effective, and as described above, this is widely used for dispersing many types of pigments in an aqueous medium. We found it effective and applied for a patent for the technology separately. (Japanese Patent Application No. 2004-379350 / 2004.12.28) The feature is that the dispersant can be used alone or as a mixture of plural kinds thereof. Such a dispersant is a white to light yellow or light brown powder compound at room temperature, and has a low solubility in an aqueous medium, but acts effectively as a dispersant for carbon black and various organic pigments in a very small amount. For example, since it is effective in a minute amount, it does not inhibit the color tone of the aqueous pigment solution composition. In addition, it has the following characteristics.

  The novel dispersant described in the previous section is a conjugate of two kinds of skeleton structures. One skeleton A is 3-hydroxy-2-naphthalenecarboxylic acid, the other skeleton B is a substituted aniline having a sulfonic acid group as an essential substituent, and the dispersant is a carboxylic acid amide in which both are bonded. When skeleton A is other than 3-hydroxy-2-naphthalene carboxylic acid such as aliphatic carboxylic acid, naphthalene carboxylic acid, benzoic acid, oxybenzoic acid, etc., even if skeleton B is skeleton B of the present invention, Other similar skeletons are not effective as dispersants. Further, even when the skeleton A is 3-hydroxy-2-naphthalenecarboxylic acid, the skeleton B is a similar skeleton other than the skeleton B described above, for example, aniline, 1-aminonaphthalene, 2-methylaniline, 2-methoxyaniline, In the case of 2-ethoxyaniline, 4-chloroaniline, 2-methyl-5-chloroaniline, 2-methoxy-5-chloroaniline, 2-methyl-4-methoxyaniline, 2,4-dimethoxy-5-chloroaniline, etc. Even so, it is not effective as a dispersant.

The novel dispersant is useful because it functions to finely and stably disperse the pigment in the aqueous medium without using a surfactant. That is, it can be used as a jet ink by adding a humectant or the like. However, it has been found by subsequent examination that the adhesion of the colorant in the printed matter is insufficient as it is and there is a problem in the scratch resistance of the printed matter.
Japanese Patent Laid-Open No. 47-30407 Japanese Patent Laid-Open No. 50-49003 JP-A-53-94581 JP 54-146109 A JP-A-55-144064 JP-A-55-145773 Japanese Patent Laid-Open No. 55-151507 JP-A-56-147863 Japanese Patent Laid-Open No. 58-2366 JP 58-45272 A JP 59-120667 A Japanese Patent Laid-Open No. 3-221137 Japanese Patent Laid-Open No. 9-151342 JP-A-9-217019 JP-A-9-272831 JP-A-11-209672 JP-A-11-293165 JP 2000-95987 A Japanese Patent Application No. 2003-285673 Japanese Patent Application No. 2004-379350 Color Material Association Journal 73 (2001), p165

  Establish water-based pigment-based jet inks with excellent storage characteristics such as pigment dispersion stability and ink ejection stability, quick drying properties, and printing properties such as water resistance of printed materials, and excellent long-term environmental durability of printed materials. It is the subject of the present invention.

  In aqueous pigment-based jet inks that use polymer-coated pigments obtained by polymerizing vinyl monomers on the surface of fine pigment particles, while reducing the amount of surfactants used, particularly those having polyoxyalkylene chain components, the ink The problem is solved by selecting an ink composition that is comprehensively excellent in stability, printability, printed matter performance, and the like. As a result, it is an application of the technology of Japanese Patent Application Nos. 2003-285673 (2003.8.4) and 2004-379350 (2004.12.28) of the present inventors.

  The jet ink composition of the present invention is a fine coating material in which a pigment colorant dispersed in water using N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide is polymer-coated with a specific acrylic resin copolymer. Particles, moisturizers that are polyhydric alcohols or their derivatives, and water are essential components, especially using N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide to reduce the amount of surfactant used An ink composition for ink jet printing characterized by the above. By selecting the composition, various environmental durability of the printed matter of the jet ink excellent in dispersion stability and printing performance was further improved.

  In the present invention, the pigments are carbon black and chromatic organic pigments, which are carbon black, azo pigments, condensed azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene pigments, perinone pigments, quinacridone by various production methods. Pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, and the like. Specific examples of these pigments are recorded in handbooks and are well known. The pigment can be used singly or as a mixture of plural kinds. Compared with carbon black and chromatic organic pigments, inorganic pigments represented by titanium oxide, zinc oxide, iron oxide and the like are not suitable because the effects of the present invention cannot be sufficiently exhibited. The mixing ratio of the pigment in the ink composition for ink jet printing according to the present invention is 0.05 to 2 wt% for light colors, or for dark colors or inks, corresponding to the jetting characteristics of jet ink and the color density requirements of printed matter. It is preferably within the range of 8 to 20 wt% for the stock solution and 2 to 8 wt% for normal use, and the present invention can be practiced within these ranges.

  N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide, which is a dispersant that can be used in the present invention, is a chemical substance defined by the above general formula (Formula 1).

  Examples of the dispersant that can be particularly preferably carried out include N-(-4-sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide, N-(-2-methyl-4-sulfoxyphenyl) -3- Hydroxy-2-naphthalenecarboxamide, N-(-2-methoxy-4-sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide, N-(-2-ethoxy-4-sulfoxyphenyl) -3-hydroxy- 2-naphthalenecarboxamide, N-(-2,4-disulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide, N-(-2-sulfoxy-4-methyl-5-chlorophenyl) -3-hydroxy-2 -Naphthalenecarboxamide, N-(-2-sulfoxy-4-methoxy-5-chlorophenyl) -3-hydroxy 2-naphthalene carboxamide and the like.

  In addition, the above-mentioned new dispersant contains 3-hydroxy-2-naphthalenecarboxylic acid corresponding to the starting material, a substituted aniline having a sulfonic acid group as an essential substituent, or inorganic salts as impurities. Since the pigment dispersing ability of the agent is remarkably reduced, it is preferable to use a purified product which is sufficiently purified, for example, having a purity of 97 wt% or more, particularly preferably 99 wt% or more. This is also a problem that should be taken into consideration for the organic pigments used. Such purification can be performed by applying general knowledge of organic synthetic chemistry.

  The mixing ratio of the dispersant in the ink for inkjet printing of the present invention is preferably in the range of 0.5 wt% to 100 wt% of the pigment used. The mixing ratio of the dispersant depends on the combination of the components used, but in many cases, it is a small ratio in the range of 0.5 wt% to 50 wt% of the pigment used, for example, 1.0 wt% to 15 wt%. It is suitable to mix within the following ranges, and the intended effect of the present invention is sufficiently exhibited. If the blending ratio with respect to the pigment is too small, fine and stable dispersion of the pigment cannot be realized, and the solubility of the dispersant in the aqueous medium is relatively low, so excessively undissolved particles are brought into the liquid composition. This is inappropriate because it needs to be removed. Although the details of the mechanism of action of the dispersant are unclear, a small amount of the dispersant dissolved in the aqueous medium in which the pigment particles are present adsorbs on the surface of the pigment particles and leaves the aqueous medium phase, and accordingly, the dispersant solid becomes the aqueous medium. When the pigment particle surface is appropriately covered with a dispersant, the pigment particles are stably dispersed by the repulsive force of the surface dispersants. It is asked from the side evidence. In this way, stable dispersion of the pigment particles in the aqueous medium is realized even in the absence of a normal surfactant. Since normally available pigment particles are agglomerated powders of primary particles, if they are finely ground by a conventionally known wet grinding method in the presence of the dispersant in an aqueous medium, they are suitable for jet inks. A stable dispersion of fine pigmented particles is obtained. When a relatively strong alkali is allowed to act on this dispersion, the alkali salt of the dispersant is liberated in the medium and the pigment is aggregated, thus demonstrating the correctness of the adsorption mechanism. As described above, the surface of the colored particles finely dispersed by adsorbing the dispersant to the pigment is covered with a vinyl monomer, and when the monomer is polymerized, a stable dispersion of the colorant coated with the vinyl polymer is obtained. . It can be used as a jet ink without being coated with a vinyl polymer, but when coated with an appropriate vinyl polymer, the colorant is covered with a polymer film in the printed matter and is protected or adhered to the substrate. Convenient.

  The use of the dispersant of the present invention provides a stable dispersion of fine pigment particles without using a surfactant, and therefore has the advantage that the vinyl polymer coating operation of the particles can be performed stably and reliably. Even if a small amount of surfactant is used for the polymer coating operation, the physical properties of the jet ink may be adjusted, for example, adjustment of the surface tension of the ink, prevention of dry solidification at the printing nozzle, and penetration of the paper. Even if a surfactant or its related substance is unavoidably added for improvement or the like, there is an advantage that the amount of the ink used can be reduced as a whole. In addition, the effect of improving ink performance is great compared to the case where a hydrophilic polymer is used as a pigment dispersant.

  In the present invention, the vinyl polymer that coats the colorant is an acrylic resin-based polymer and is a water-insoluble polymer. From the viewpoint of dispersion stability, the case where the vinyl polymer is a polymer of one or more monomers selected from Group A monomers represented by the general formula (Chemical Formula 3) is selected. The invention is feasible. If other monomers are used as a basis, it is difficult to coat all of the pigment particles with a resin and to secure the dispersion stability of the coated pigment.

The composition of the polymer of the group A monomer is selected so that the physical properties of the ink solid after printing mainly meet the required properties of the printed material, particularly the properties and usage state of the printed object. For example, depending on whether the object to be printed is paper, cloth, plate or the like and how it is used, the melting point, softening point, secondary transition point, adhesion, solvent resistance, resistance of the polymer Since required levels such as flexibility and friction resistance are different, the polymer composition is selected so as to meet the requirements. This polymer composition selection can be made by applying the knowledge of polymer chemistry already well known to those skilled in the art.

  In order to improve the printability by modifying the physical properties of the colorant-coated polymer of the present invention and to maintain the high storability of the ink, the coated polymer can be copolymerized with the group A monomer. And an acrylic resin copolymer obtained by copolymerizing at least one of group B monomers composed of a specific fluorine-containing monomer represented by a ratio of 10 to 800 wt% with respect to the group A monomer. Is possible. The group B monomer selected in this way is a monomer that can be polymerized in the same manner as the group A monomer. In particular, it is preferable to use the group B monomer in the range of 15 to 150 wt% with respect to the group A monomer in order to express the above-mentioned objective effect remarkably. If it is lower than this range, the dispersion stabilization effect may be insufficient depending on the type of dispersion target, and if it is excessive, the water resistance improvement effect is saturated and it is often uneconomical.

  Moreover, the improvement of the object could not be achieved with silicon-containing monomers and hydrocarbon monomers. Even in the case of the fluorine-containing monomer, if the number of carbon atoms in Z is excessive, it is unsuitable because it causes defects in the polymer coating of the pigment in cooperation with the group A monomer. As a monomer represented by the formula (4) and used in the present invention, 2,2,2-trifluoroethyl methacrylate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl Typical examples include acrylate, 1H, 1H, 5H-octafluoropentyl acrylate, and 1H, 1H, 5H-octafluoropentyl methacrylate. However, when the number of carbon atoms of Z such as perfluorooctylethyl (meth) acrylate is excessive, a preferable polymer coating cannot be performed.

  In the present invention, the fluorine-containing monomer represented by (Chemical Formula 4) is a preferred component, but has one vinyl group in the molecule capable of copolymerizing a part of the group A monomer, and the group A monomer and It is also possible to replace in the range of 5 to 40 wt% with one or more of group C vinyl monomers which are hydrophobic vinyl monomers not belonging to any of group B monomers. The hydrophobic monomer corresponds to the homopolymer of the monomer being water-insoluble, and examples thereof include styrene, vinyl toluene, vinyl chloride, vinylidene chloride, acrylonitrile, vinyl acetate, and α-olefin. These are selected and used according to the application from the viewpoint of the required physical properties of the solidified ink on the printed matter, in particular from the viewpoint of reinforcing the water resistance. However, if used in a large amount, care must be taken because the surface of the colorant is completely covered and its dispersion stability is impaired. From the above viewpoint, it is preferable to replace in the range of 10 to 40 wt%.

  In the present invention, a part of the group A monomer is a copolymerizable vinyl group and a hydrophilic substituent which is any one of a hydroxyl group, an amino group, a sulfonic acid group, a carboxylic acid group, or a salt group thereof. It is possible to replace in the range of 5 to 20 wt% with one or more of the group D vinyl monomers which are vinyl monomers having the following. Examples of Group D monomers include hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, vinyl sulfonic acid, acrylic acid, methacrylic acid and the like. When the pigment-coated polymer contains a group D monomer by copolymerization, it has effects such as higher hydrophilicity of the coating and further improved dispersion stability, or higher adhesion of the ink. However, excessive copolymerization is not preferable because it brings about disadvantages such as contact with water and swelling of the coated body to become sticky, or a decrease in water resistance of the printed matter. Although it depends on the composition of the coating polymer, generally speaking, it is possible to contain the group D monomer in a proportion of 20 wt% or less of the group B monomer, and particularly a proportion of 10 wt% or less is preferable.

  In the present invention, in addition to the group A monomer and the group B monomer, the group E monomer having a vinyl group copolymerizable therewith in the range of 2 to 5 in the molecule is added to the total amount of the monomers of both groups. It is possible to make it contain in the ratio below 30 wt%. Examples of this polyfunctional vinyl monomer include divinylbenzene, trimethylolpropane trisvinyl acetate, pentaerythritol pentavinyl acetate, and the like. The pigment-coated polymer is made by copolymerizing the group E monomers, and the softening temperature of the coated resin is high and the particles become stronger. Stability is improved. Further, although the reason is not known, it is recognized that the printing density is improved in the case of the printed matter having the same colorant concentration and the E group monomer copolymer coating. However, since the effect is saturated even if it is excessively copolymerized, it varies depending on the composition of the coating polymer, but generally speaking, the E group monomer should be contained in a proportion of 25 wt% or less with respect to the total amount of both AB group monomers. Is preferred.

  The vinyl polymer coating amount of the colorant in the present invention can be carried out in the range of 10 to 150 wt% based on the pigment weight. If the amount is less than the above range, the dispersion stability of the coated pigment in the jet ink is insufficient, and if too large, the dispersion stability is saturated, which is uneconomical. From such a viewpoint, a coating amount of 40 to 100 wt% is preferable.

  In order to polymerize and coat a pigment-based colorant, it is necessary to coat the colorant with a coating monomer in advance, and the monomer particles containing the fine colorant are dispersed stably in an aqueous medium during the polymerization operation. It is necessary to make it. This requires the use of a surfactant, also called an emulsifier in the emulsion field, or the use of a comonomer having a self-emulsifying action instead of using a surfactant. In particular, it is important to select a surfactant that can stably disperse a monomer containing a fine colorant in an aqueous medium even at the polymerization temperature and that does not inhibit the polymerization. Selection from this viewpoint can be performed by applying a well-known emulsion technique, and can be easily performed experimentally by at least a technician in the technical field. The fine colorant-containing vinyl polymer that forms part of the present invention is obtained by mixing an aqueous dispersion of a fine colorant and an aqueous dispersion of a coating monomer in the presence of a water-soluble polymerization initiator. As the droplets coalesce, the monomer droplets split and change to a monomer dispersion containing a fine colorant. To accelerate this change, it is advantageous to stir the system under relatively mild conditions. During this change, the relatively large original monomer droplets that do not contain the fine colorant have disappeared. This is presumed to be due to a kind of salting-out effect of persulfate, which is a water-soluble polymerization initiator, but for some reason, an aqueous dispersion of a fine monomer containing a fine colorant can be easily obtained. However, even if sodium sulfate or sodium chloride generally used as a salting-out agent is present in the absence of a persulfate, a change to a monomer dispersion containing the fine colorant does not occur. Therefore, it is not recognized to be due to a normal salting-out effect, and is a special effect of persulfate, and the use of persulfate is an essential condition in the method of the present invention. When the above-mentioned dispersion is heated to a temperature higher than the decomposition temperature of the polymerization initiator, polymerization of the vinyl monomer occurs, and an aqueous dispersion of a fine colorant coated with polymerization is obtained. If the polymerization initiator and polymerization temperature / time are selected, the polymerization of the monomer is quantitative, and this is also clear from the disappearance of the monomer odor of the reaction system.

  In the present invention, a water-soluble persulfate such as potassium persulfate or ammonium persulfate is used as the polymerization initiator for coating the colorant pigment. The amount of the polymerization initiator used is preferably in the range known in emulsion polymerization. When copolymerizing a highly hydrophobic monomer such as styrene, it is preferable to use a water-insoluble polymerization initiator together because the polymerization rate of the hydrophobic monomer is improved. The water-insoluble polymerization initiator is preferably dissolved in a water-soluble organic solvent and added to the system. As such a polymerization initiator, known initiators such as benzoyl peroxide, azobisisobutyronitrile, cumene hydroperoxide, and tert-butyl peroxide can be used. However, from the above-described phenomenon of persulfate, polymerization with only these water-insoluble polymerization initiators is inappropriate. In the coating polymerization, as already known, it is possible to accelerate the polymerization by coexisting a reducing agent. The salt produced in the composition of the present invention by the use of persulfate causes the liquid composition after coating polymerization or the ink prepared therefrom to be removed by ion exchange resin treatment or electrophoretic treatment, causing nozzle clogging in the printing press. It can be avoided.

  The ink composition for inkjet printing of the present invention can contain a surfactant as a constituent component. The surfactant is a conventionally known surfactant having a relatively low molecular weight, for example, a molecular weight of about 1000 or less. High molecular weight surfactants can be used, but are not preferred because of the disadvantages described above. However, this does not prevent the use of a small amount of a polymer surfactant having a molecular weight that is not so high. In the present invention, there are two aspects where the use of a surfactant should be considered. One is the preparation of a fine aqueous dispersion of the pigment before polymerization coating. The other is an aspect of stable handling of an aqueous emulsion of a coated monomer to be subjected to polymerization coating and stabilization of an emulsion containing a colorant after polymerization coating. On the other hand, as described above, the presence of the surfactant adversely affects the environmental durability of the printed material, and therefore its use should be minimized. In particular, in the present invention, the amount of the surfactant having a polyoxyalkylene chain component is desired to be minimized. For this reason, in the present invention, N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide is used as a dispersant instead of a surfactant in preparing a fine aqueous dispersion of a pigment before polymerization coating, which is the first aspect. The greatest feature is that a desired dispersion is realized by using. The use of a surfactant that contributes to the stabilization of the emulsion as the second aspect is inevitable. However, the use of a surfactant having a polyoxyalkylene chain component should be avoided or reduced as much as possible, and other types of surfactants should be selected and used. Since suitable surfactants differ depending on the combination and blending ratio of the emulsion monomers to be used, a surfactant that does not hinder emulsion stabilization and polymerization coating may be selected from existing products each time. This selection can be performed at least experimentally by those skilled in the art. In this case, copolymerization of a monomer having a hydrophilic group imparting self-emulsifying property to the polymer-coated copolymer instead of the surfactant can also be used. The copolymerization of the hydrophilic monomer is as described above.

  As the surfactant, a substance effective for dispersing the coating colorant and reducing the viscosity of the ink is selected and used, except for the suitability in the polymerization coating step. Since a suitable surfactant varies depending on the type of polymer of the coating colorant and the ink medium composition, it is experimentally selected according to the above-mentioned criteria for use. This selection can be made by experimental means well known to those skilled in the art. In other words, since the dispersion stability of the coating colorant, the ejection property and the stability of the ink in the ink jet printer to be used, and the type and amount of the surfactant used in the evaluation tests such as various durability of the printed matter are selected. is there. Surfactants used include alkyl sulfate, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, naphthalene sulfonate-formalin condensate, sulfosuccinate, alkyl amide sulfate, alkyl Anionic surfactants such as phosphate ester salts, cationic surfactants such as aliphatic quaternary ammonium salts, aromatic quaternary ammonium salts and heterocyclic quaternary ammonium salts, amphoteric compounds such as carboxybetaine and aminocarboxylate Used by selecting from surfactants. The blending amount of the surfactant varies depending on the components other than the activator and the amount thereof, but is generally within the range of 3 to 15 wt% of the colorant. If the amount is too small, the effect of the activator is insufficient. On the other hand, if the amount is too large, defects such as deterioration of the environmental durability of the printed matter and nozzle stains of the printing press occur. However, nonionic anionic surfactants such as polyoxyalkylene alkyl ether sulfates, polyoxyalkylene alkyl ether carboxylates, polyoxyalkylene alkyl ether phosphates, polyoxyethylene alkyl ethers and polyoxyethylene polyoxy Nonionic surfactants such as propylene block copolymers and polyoxyethylene ethers of sorbitol esters are desired to be avoided as much as possible from the viewpoint of environmental durability of printed matter.

  The jet ink of the present invention can be used as a surface tension adjusting agent, for example, polyoxyethylene laurether-based surfactant, polyoxyethylene alkyl ether sulfate ester salt, polyoxyethylene alkyl ether phosphorus, depending on its application and printing machine characteristics. Acid ester salts, acetylene glycols and their ethylene oxide adducts can be added in a small amount of a non-basic or weakly basic surfactant, that is, in an acceptable range that does not significantly contradict the purpose of the invention. It is possible to add a small amount of a basic surfactant to the liquid after the polymerization coating is completed. In printing on paper, cloth or wood, these promote ink penetration and enable fine printing without bleeding at high speed. However, even in this case, it is desirable to use other types of surfactants in order to avoid the use of surfactants as much as possible from the viewpoint of environmental durability of the printed matter.

  Although the medium in the ink composition of the present invention is water, the ink contains a humectant to prevent the ink from drying and concentrating during use. Conventionally, a wide variety of compounds have been proposed as humectants, but in the present invention, it is possible to use one or more water-soluble compounds selected from polyhydric alcohols or ethers or ester derivatives thereof, and desirable. In the present invention, the polyhydric alcohol is a compound having two or more hydroxyl groups in the molecule, and can be cited as a typical example of a polyhydric alcohol that can be practiced by ethylene glycol, propylene glycol, butylene glycol, glycerin and the like. Aliphatic polyhydric alcohols having a large number of carbon atoms are not suitable because they are poorly water-soluble and poor in action as humectants.

  The ether derivative of a polyhydric alcohol useful as a humectant is preferably a monoalkyl ether of the above-mentioned glycol, and a bisalkyl ether is not preferred because it is inferior in moisture retention to the monoether. However, the glycerin alkyl ether can be suitably used because it is effective even with a bisalkyl ether. In short, one of the hydroxyl groups possessed by the polyhydric alcohol remains a hydroxyl group, and a compound in which the other hydroxyl group is etherified has suppressed volatility and can be suitably used as a humectant. The alkyl group of the alkyl ether is preferably an alkyl having 5 or less carbon atoms. A larger carbon number is not suitable because the water solubility of the compound is low and the effect is poor. Examples of suitable polyhydric alcohol ether derivatives include ethylene glycol, propylene glycol, monomethyl ether of butylene glycol, monoethyl ether and monobutyl ether, and mono- or bisethyl ether of glycerin. Use of an ethylene oxide adduct, a propylene oxide adduct, and a tetramethylene oxide adduct of polyhydric alcohols is not preferable from the viewpoint of the present invention from the viewpoint of environmental durability of the printed material, but is preferable from the viewpoint of ink printability. It is a compound belonging to the technical scope as a practicable ether derivative of a polyhydric alcohol. It is better to use a balance of both performances according to the application.

  The polyhydric alcohol ester derivative useful as a humectant is also preferably a mono fatty acid ester of the polyhydric alcohol. Mono-fatty acid esters of glycol are preferred, and bis-fatty acid esters are less preferred because they are less moisturizing than monoesters. However, glycerin fatty acid esters can be suitably used because they are effective even with bisesters. In short, one of the hydroxyl groups possessed by the polyhydric alcohol remains a hydroxyl group, and a compound in which the other hydroxyl group is esterified with a fatty acid is suppressed in volatility and can be suitably used as a humectant. The fatty acid of the fatty acid ester is preferably an aliphatic carboxylic acid having an alkyl group with 3 or less carbon atoms. A larger carbon number is not suitable for use as a humectant because the water solubility of the compound decreases. Suitable ester derivatives of polyhydric alcohols include ethylene glycol, propylene glycol, butylene glycol monoacetate, monolactate, monopropionate, and glycerol mono- or bisacetate. Can be mentioned.

  The compounds useful as humectants described above are low in volatility and water-soluble, and are used in combination with the polymer coating colorant of the present invention to constitute an aqueous pigment jet ink having excellent pigment dispersion stability. Can do. Diethylene glycol monobutyl ether, triethylene glycol monobutyl ether or tetraethylene glycol monoethyl ether as a humectant is preferable not only for ensuring the dispersion stability of the pigment and enhancing the moisturizing effect of the ink, but also for the penetration speed of the ink into the printing surface. Is also large and preferable. However, as a result of a wide variety of practical printing tests, the polymer coated pigments that are not copolymerized with the fluorine-containing monomer represented by (Chemical Formula 4) are intended to further improve the water resistance of the printed ink and to disperse the colorant. In the case where there is a strong demand for further improving the stability and ensuring long-term ejection stability, the requirement is satisfied with the polymer coating colorant copolymerizing the fluorine-containing monomer represented by (Chemical Formula 4) of the present invention. Is satisfied. And the above-mentioned moisturizing agent exhibits its effect sufficiently. The blending ratio of such a humectant in the ink composition for ink-jet printing varies depending on the combination of the type of humectant and the polymer coating colorant, but is generally in the range of 0.5 to 60 wt%. It is preferable to select and use within the range of ˜30 wt%. This is because if the amount is too small, the effect of preventing difficulty due to drying of the ink on the nozzle surface is low, and if the amount is too large, the viscosity of the ink is high so that it is difficult to perform ejection or fine and clear printing.

  The jet ink of the present invention is not very preferable, but it can be added with a small amount of a water-soluble polymer in order to obtain a viscosity according to the characteristics of the equipment used. In addition, a resin emulsion containing a hydrophilic polymer or a water-insoluble polymer as a main component can be added for fixing the colorant. In this case, it is preferable to select and use a non-basic compounding agent, but after the completion of the polymerization coating, it is possible to add and mix a small amount of the basic resin emulsion. Examples of water-soluble polymers include polyvinyl alcohol, water-soluble acrylic resins, polyacrylamide, water-soluble cellulose derivatives and the like, and examples of resin emulsions where o / w emulsions such as vinyl chloride-vinyl acetate resin and polyurethane resin can be implemented. As mentioned.

  In addition to the substances described above, conventionally known wetting agents, penetrating agents, leveling agents, preservatives, pH adjusters, etc. in this field are used depending on the purpose and the substances allowed for the purpose of the present invention and their amounts. It is possible to add and mix additionally.

  The jet ink composition of the present invention is a fine coating material in which a pigment colorant dispersed in water using N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide is polymer-coated with a specific acrylic resin copolymer. Particles, moisturizers that are polyhydric alcohols or their derivatives, and water are essential components, especially using N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide to reduce the amount of surfactant used An ink composition for ink jet printing characterized by the above. By selecting this composition, various environmental durability of the printed matter of jet ink excellent in dispersion stability and printing performance was further improved, and an ink composition excellent in overall performance could be realized.

  In the following, typical examples will be described to give a more specific explanation of the present invention, but the embodiments of the present invention are not limited thereto. In the following, parts are parts by weight. The particle size of the colorant in the ink is a value measured by UPA-150 manufactured by Microtrac, a laser Doppler type particle size measuring device, the viscosity of the ink is a value measured by a B-type viscometer, and the surface tension is Kyowa Interface Science ( This is a value measured by a surface tension measuring instrument CBVP-A3 manufactured by Co., Ltd.

(Example 1) Carbon black as a black pigment (CI Pigment Black 7: Carbon Black # 45L manufactured by Mitsubishi Chemical Corporation), 80.0 parts, N-(-4-sulfoxyphenyl) -3-hydroxy as a dispersant The mixture was mixed at a ratio of 8.0 parts of 2-naphthalenecarboxamide, 30.0 parts of glycerin and 300.0 parts of ion-exchanged water, and the pigment was ground and dispersed in a bead mill using zirconia beads having a diameter of 0.3 mm for 10 hours. . Thus, a coarsely concentrated colorant liquid composition in which the pigment adsorbed the dispersant and dispersed as fine particles was obtained. The paste is centrifuged to separate and remove coarse particles of carbon black and some undissolved components of N-(-4-sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide, and filter through a 1 μ filter. A water-based colorant concentrated liquid composition was obtained. At this time, filtration was easy and completed within a short time. The composition ratio of the dispersion was not substantially changed by centrifugation or filtration. On the other hand, 24.0 parts of methyl methacrylate, 20.0 parts of n-butyl methacrylate, 2,4.0 parts of 2,2,2-trifluoroethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd .: Light Ester M-3F), neopentyl glycol dimethacrylate ( Kyoeisha Chemical Co., Ltd .: Light Ester NP) 12.0 parts, Surfactant Hytenol 18E (Daiichi Kogyo Seiyaku: Low molecular weight polyoxyethylene glycol oleyl ether ammonium sulfate) 4.0 parts, ion-exchanged water 50.0 parts The mixture was stirred with a homogenizer to prepare an emulsion of a vinyl monomer. Tert-Butylperoxy-2-ethylhexano for complete polymerization of ammonium persulfate 6.0 parts, dimethylethanolamine 5.0 parts, polyfunctional methacrylate in 400 parts of the above aqueous colorant concentrate composition After adding 1.0 part of ate (manufactured by NOF Corporation: oil-soluble polymerization initiator Perbutyl O), the emulsion of the vinyl monomer was added dropwise with stirring. Observing when stirring for 15 minutes after the completion of dropping, monomer fine particles containing fine colorant particles were dispersed in water, and relatively large particles of the monomer emulsion before mixing were lost. The system was then heated to 85 ° C. under a nitrogen stream and maintained at that temperature for 6 hours with stirring. The monomer odor of the liquid disappeared, and a dispersion of the vinyl polymer-coated colorant was obtained. Coarse particles present in very small amounts were removed by centrifugation and three filtrations. The polymerization was quantitative. Glycerin, diethylene glycol, triethylene glycol monobutyl ether, 2-pyrrolidone as a dispersion aid, ethylene oxide adduct of acetylene glycol as a penetrant (manufactured by Nisshin Chemical) : Orphine E-1010) and ion-exchanged water were added, and the final composition was a coating colorant content of 5.0 wt%, glycerin 10.0 wt%, diethylene glycol 4.0 wt%, 2-pyrrolidone 8.0 wt%, triethylene glycol An aqueous pigment jet ink comprising 6.0 wt% monobutyl ether, 2.0 wt% Olfine E-1010, 0.12 wt% surfactant Hytenol 18E, and the balance of 100.0 wt% in total with water remaining. The viscosity of this ink was 3.3 mPa · s, the average particle size of the coating colorant was 0.09 μm, and the pH was 8.5. These values did not change after standing at 50 ° C. for 30 days, and no aggregation or precipitation of the coating colorant was observed. Both the ink just after preparation and the ink after heating and standing are loaded into Saar's Xajet XJ128 / 360/55, which is an ink jet printer using piezo elements, and an ink jet printing test on roll paper can be performed smoothly. It was. In the printing test, a cycle of 16 hours of continuous printing and 8 hours of interruption was continued for 7 days. The printing nozzles were not clogged, and it was possible to continue to resume clear and dark printing smoothly. The ink did not bleed even when water was dropped on the printed matter. Although the printed matter was observed after being subjected to a 14-day weather resistance test, neither the appearance of the printed matter nor the colorant was removed in the rubbing test.

(Comparative Example 1) For comparison with Example 1, the preparation step of the crude concentrated colorant liquid composition of Example 1 was carried out using N-(-4-sulfoxyphenyl) -3-hydroxy-2-2 as a dispersant. Without using 8.0 parts of naphthalenecarboxamide and 22.0 parts of ion-exchanged water, 30.0 parts of the surfactant Hytenol 18E was added. The use of 30.0 parts of the surfactant is a condition separately selected for realizing a pigment dispersion state equivalent to that in Example 1. Thereafter, the method of Example 1 was repeated to prepare a jet ink having the same pigment concentration and a high concentration of 1.02 wt% of the surfactant Hitenol 18E in the ink. The ink dispersion stability and printability were the same as in Example 1. The appearance after the weathering test was the same, but the colorant was removed in the rubbing test.

Example 2 The black pigment of Example 1 was replaced with a blue organic pigment C.I. I. The method of Example 1 was repeated in place of Pigment Blue 15-4 (Toyo Ink Co., Ltd .: Lionol Blue 7400G) to prepare a jet ink using a blue pigment. The ink was allowed to stand at 50 ° C. for 30 days, but no aggregation or precipitation of the coated colorant particles was observed. Both the ink just after preparation and the ink after heating and standing are loaded into Saar's Xajet XJ128 / 360/55, which is an ink jet printer using piezo elements, and an ink jet printing test on roll paper can be performed smoothly. It was. In the printing test, a cycle of 16 hours of continuous printing and 8 hours of interruption was continued for 7 days. The printing nozzles were not clogged, and it was possible to continue to resume clear and dark printing smoothly. The ink did not bleed even when water was dropped on the printed matter. Although the printed matter was observed after being subjected to a 14-day weather resistance test, neither the appearance of the printed matter nor the removal of the colorant in the rubbing test was observed.

(Comparative Example 2) For comparison with Example 2, the black pigment of Comparative Example 1 was replaced with the blue organic pigment C.I. I. Instead of Pigment Blue 15-4, the method of Comparative Example 1 was repeated to prepare a jet ink using a blue pigment. The dispersion stability and printing performance of this ink were the same as those in Example 2. However, as a result of subjecting the printed matter to a weather resistance test for 14 days, the printing density was slightly lowered, and the colorant dropped off in the scratch test. Admitted to do.

Example 3 Red organic pigment C.I. I. Pigment Red 238 (manufactured by Sanyo Dye: Permanent Carmine 3810) 200.0 parts, dispersant N-(-2-methoxy-4-sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide 15.0 parts, glycerin 100. 0 parts and 285.0 parts of ion-exchanged water were placed in a container, and the pigment was ground and dispersed in a bead mill for 12 hours to obtain a coarsely concentrated colorant liquid composition in which the pigment adsorbed the dispersant and dispersed as fine particles. . This was added to 400.0 parts of ion-exchanged water with stirring, and centrifuged to obtain coarse particles of carbon black or one of N-(-2-methoxy-4-sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide. Part of the undissolved portion was separated and removed, and further filtered through a 1 μ filter to obtain a concentrated aqueous colorant composition. At this time, filtration was easy and completed within a short time. The composition ratio of the dispersion was not substantially changed by centrifugation or filtration. On the other hand, 15.0 parts of n-butyl methacrylate, 30.0 parts of n-butyl acrylate, 2,2,2-trifluoroethyl methacrylate (manufactured by Kyoeisha Chemical Co., Ltd .: Light Ester M-3F), 15.0 parts of trimethylolpropane tri 4.0 parts of methacrylate (manufactured by Kyoeisha Chemical Co., Ltd .: Light Ester TMP), 9.2 parts of surfactant olefin-maleic acid copolymer N-dimethylethanolamine (manufactured by Kyoeisha Chemical Co., Ltd .: 70% product), and 70 parts of ion-exchanged water. 0 parts was mixed and stirred with a homogenizer to prepare a vinyl monomer emulsion. To 320 parts of the aforementioned aqueous colorant concentrated liquid composition, 3.0 parts of ammonium persulfate, 50.0 parts of ion-exchanged water, 3.0 parts of dimethylethanolamine, and tert-butylperoxy-2-ethylhexanoate (Japan) Product made from fats and oils: After adding 1.0 part of oil-soluble polymerization initiator perbutyl O), the emulsion of the vinyl monomer was added dropwise with stirring. When observed when stirring for 20 minutes after the completion of dropping, the monomer fine particles containing the pigment were dispersed in water, and the relatively large particles of the monomer emulsion before mixing disappeared. The system was then heated to 85 ° C. under a nitrogen stream and maintained at that temperature for 6 hours with stirring. The monomer odor of the liquid disappeared, and a dispersion of the vinyl polymer-coated pigment was obtained. Coarse particles present in very small amounts were removed by centrifugation and three filtrations. The polymerization was quantitative. Various chemicals and ion-exchanged water are added to the dispersion of the pigment coated with the obtained fluorine-containing copolymer, and the final composition is a coating colorant content of 6.0 wt%, glycerin 15.0 wt%, and 1,5-pentanediol. 2.75 wt%, triethylene glycol monobutyl ether 8.0 wt%, Olphine E-1010 2.0 wt%, surfactant olefin-maleic acid copolymer N-dimethylethanolamine salt 0.42 wt%, balance is water A total of 100.0 wt% aqueous pigment-based jet ink was prepared. When this ink was allowed to stand at 50 ° C. for 4 weeks, no aggregation or precipitation of the coating colorant was observed. When the ink-jet printing test was carried out by the method described in Example 1 for both the ink immediately after preparation and the ink after heating and standing, the printing nozzles were not clogged for 7 days, and clear and dark color printing was smoothly performed. The ink did not bleed even when water was dropped on the printed matter. As a result of subjecting the printed matter to a weather resistance test for 14 days, neither the appearance of the printed matter nor the colorant was removed in the rubbing test.

(Comparative Example 3) For comparison with Example 3, the preparation step of the crude concentrated colorant liquid composition of Example 3 was carried out using the dispersant N-(-2-methoxy-4-sulfoxyphenyl)-as the dispersant. Instead of using 15.0 parts of 3-hydroxy-2-naphthalenecarboxamide and a part of ion-exchanged water, the surfactant Hytenol NF- which is a distyrylphenol ether ammonium sulfate of low molecular weight polyoxyethylene glycol instead. 08 (Daiichi Kogyo Seiyaku Co., Ltd.) 160.0 parts was added, and the method of Example 3 was repeated to obtain a total amount of 1000 parts of a crude concentrated colorant solution composition. The amount of the surfactant used is a separately selected condition for realizing a pigment dispersion state equivalent to that in Example 3. In the subsequent operation, the method of Example 3 was repeated to prepare a jet ink having the same pigment concentration and a concentration of the surfactant Hitenol NF-08 in the ink of 2.31 wt%. When this ink was allowed to stand at 50 ° C. for 4 weeks, no aggregation or precipitation of the coating colorant was observed. When the ink-jet printing test was carried out by the method described in Example 1 for both the ink immediately after preparation and the ink after heating and standing, the printing nozzles were not clogged for 7 days, and clear and dark color printing was smoothly performed. The ink did not bleed even when water was dropped on the printed matter. As a result of subjecting the printed matter to a weather resistance test for 14 days, the printing density was slightly lowered, the color tone was also changed, and it was found that the colorant dropped off in the rubbing test.

Example 4 The red organic pigment in Example 3 was replaced with the yellow organic pigment C.I. I. Pigment Yellow 74 (manufactured by Clariant: Hanser Yellow 5GXB) and N-(-2-methoxy-4-sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide were added to N-(-2-sulfoxy-4-methyl-5). The method of Example 3 was repeated instead of -chlorophenyl) -3-hydroxy-2-naphthalenecarboxamide. The dispersion stability, printability, weather resistance, etc. of the obtained ink were satisfactory as in Example 4.

Comparative Example 4 The method of Comparative Example 3 was repeated using the yellow organic pigment and dispersant in Example 4.
Although the dispersion stability and printability of the ink obtained were satisfactory, the weather resistance of the printed matter had the same difficulties as in Comparative Example 3.

Claims (9)

In water-based pigment ink in which a pigment-based colorant coated with a vinyl polymer is dispersed in an aqueous medium, (1) one kind selected from carbon black or chromatic organic pigment as a main component as a colorant A colorant comprising the above pigment and one or more selected from the group of N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide represented by the following general formula (Formula 1) as a subcomponent: (2) One or more monomers selected from Group A monomers consisting of acrylic acid esters and methacrylic acid esters represented by the following general formula (Formula 3) as the vinyl polymer covering the colorant, or An acrylic resin copolymer obtained by copolymerizing one or more monomers selected from group B monomers consisting of a specific fluorine-containing monomer represented by the general formula (Chemical Formula 4); (3) a polyhydric alcohol or an ether thereof. Also One or more humectants selected from ester derivatives, and (4) ink jet printing ink composition characterized by comprising water as essential components.



(However, the carboxamide is N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide, the basic component of which is represented by the following chemical structural formula (Formula 2)).

(In the above formula, A is an alkyl group having 1 to 4 carbon atoms, and Ph is a phenyl group.)

(Chemical formula 3)
CH2 = C (X) COOR

(However, in the above formula, X is either H or CH3, and R is either a linear or branched alkyl group having 6 or less carbon atoms having no hydrophilic substituent.)

(Chemical formula 4)
CH2 = C (Y) COOCH2Z

(However, in the above formula, Y is either H or CH3, and Z is a linear or branched fluorine-substituted alkyl group having 5 or less carbon atoms having fluorine as a substituent.)
  The usage rate of the accessory component N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamide in the colorant according to claim 1 is 0.5 wt% or more and 50 wt% or less of the used pigment as the main component. The ink composition for inkjet printing according to claim 1.   The acrylic resin-based copolymer that coats the colorant is an acrylic resin-based copolymer obtained by copolymerizing the group B monomer at a ratio in the range of 10 to 800 wt% with respect to the group A monomer. The ink composition for inkjet printing according to claim 1 or 2.   One or more of the group C vinyl monomers, wherein a part of the group A monomer has one copolymerizable vinyl group in the molecule and is a hydrophobic vinyl monomer that does not belong to either the group A monomer or the group B monomer The ink composition for ink jet printing according to claim 2, wherein the ink composition is replaced by 10 to 40 wt%.   A part of the group A monomer is a vinyl monomer having a copolymerizable vinyl group and a hydrophilic substituent which is any one of a hydroxyl group, an amino group, a sulfonic acid group, a carboxylic acid group, or a salt group thereof. 5. The ink composition for ink jet printing according to claim 2, wherein the ink composition is replaced in the range of 5 to 20 wt% by one or more kinds of a certain group D vinyl monomer.   In addition to the group A monomer and the group B monomer, the group E monomer having a vinyl group copolymerizable therewith in a range of 2 to 5 in the molecule is 30 wt% with respect to the total amount of the monomers of both groups. 6. The ink composition for ink jet printing according to claim 2, wherein the ink composition is contained in the following ratio.   The blending ratio of the constituents in the ink composition for ink jet printing is such that the colorant is 2 to 8 wt%, the acrylic resin-based copolymer covering the colorant is 40 to 100 wt% of the colorant, and the humectant is 10 to 40 wt%. The ink composition for ink jet printing according to any one of claims 2, 3, 4, 5, and 6, wherein the ink composition is selected from a range, and the remainder is water or water and a small amount of a surfactant.   Fine dispersion of one or more pigments selected from carbon black or chromatic organic pigments using one or more of N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamides according to claim 1 A process for producing a colorant dispersion, a process for emulsifying a vinyl monomer in water, a mixture of the colorant dispersion and the vinyl monomer emulsion in the presence of a persulfate, and a fine vinyl in which pigment particles are present in the emulsion particles. The ink for inkjet printing according to any one of claims 1 to 6, comprising a step of forming a monomer emulsion, and a step of polymerizing the monomer by heating the obtained monomer-containing monomer emulsion. A method for producing a vinyl polymer-coated pigment dispersion which is a precursor of a composition. Fine dispersion of one or more pigments selected from carbon black or chromatic organic pigments using one or more of N- (sulfoxyphenyl) -3-hydroxy-2-naphthalenecarboxamides according to claim 1 A process for producing a colorant dispersion, a process for emulsifying a vinyl monomer in water, a mixture of the colorant dispersion and the vinyl monomer emulsion in the presence of a persulfate, and a fine vinyl in which pigment particles are present in the emulsion particles. A step of preparing a monomer emulsion, a step of polymerizing the monomer by heating the monomer emulsion containing the pigment, and one or more moisturizers selected from polyhydric alcohols or ethers or ester derivatives thereof in the polymerization completion liquid. The ink composition for ink jet printing according to any one of claims 1 to 6, wherein the ink composition for ink jet printing comprises Law.