JP2013079293A - Water-based ink for inkjet recording and ink cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide water-based ink for inkjet recording excellent in hue and in fastness against light, heat and ozone and prevented from causing reduction in an optical density (OD value) in a high humidity environment.SOLUTION: The water-based ink for inkjet recording includes a colorant, water, and a water-soluble organic solvent. The colorant includes a dye represented by general formula (1). The water-based ink further includes a cationic polymer. In general formula (1): Ris a hydrogen atom, a substituted/unsubstituted alkyl group, or a substituted/unsubstituted aryl group; Ris a hydrogen atom, a halogen atom or a cyano group; Ris a hydrogen atom, a substituted/unsubstituted alkyl group, a substituted/unsubstituted aryl group, or a substituted/unsubstituted heterocyclic group; R, R, Rand Rare each a hydrogen atom, a substituted/unsubstituted alkyl group, a substituted/unsubstituted aryl group, a substituted/unsubstituted heterocyclic group, a substituted/unsubstituted sulphonyl group, or a substituted/unsubstituted acyl group wherein R, R, Rand Rmay be the same or different provided Rand Rare not hydrogen atoms at the same time and Rand Rare not hydrogen atoms at the same time; and Aand Aare both substituted/unsubstituted carbon atoms, or one of them is a substituted/unsubstituted carbon atom while the other is a nitrogen atom.

Description

  The present invention relates to an aqueous ink for ink jet recording and an ink cartridge.

  Ink-jet recording water-based inks are generally required to have good hues and excellent fastness to light, heat, and ozone. Water-based inks using specific dyes have been proposed as water-based inks for inkjet recording having good hue and excellent fastness (Patent Documents 1 to 3).

JP 2007-217523 A JP 2007-217524 A JP 2007-217525 A

  However, some of the specific dyes are more likely to change in the ease of diffusion to the recording medium due to changes in environmental conditions of use than general dyes. For example, humidity affects the ease of diffusion of the specific dye into the recording medium. For this reason, in a high humidity environment, when ink jet recording is performed using an aqueous ink containing the specific dye, there is a problem that the optical density (OD value) is lowered.

  Accordingly, the present invention provides a water-based ink for inkjet recording that has a good hue, excellent fastness to light, heat, and ozone, and that suppresses a decrease in optical density (OD value) in a high humidity environment. Objective.

一般式（１）において、
Ｒ_１は、水素原子、置換又は無置換のアルキル基、置換又は無置換のアリール基であり、
Ｒ_２は、水素原子、ハロゲン原子又はシアノ基であり、
Ｒ_３は、水素原子、置換又は無置換のアルキル基、置換又は無置換のアリール基、置換又は無置換のヘテロ環基であり、
Ｒ_４、Ｒ_５、Ｒ_６及びＲ_７は、それぞれ、水素原子、置換又は無置換のアルキル基、置換又は無置換のアリール基、置換又は無置換のヘテロ環基、置換又は無置換のスルホニル基、置換又は無置換のアシル基であり、Ｒ_４、Ｒ_５、Ｒ_６及びＲ_７は同一でも異なっていてもよいが、Ｒ_４及びＲ_５が共に水素原子であることはなく、Ｒ_６及びＲ_７が共に水素原子であることはなく、
Ａ_１及びＡ_２は、双方が置換又は無置換の炭素原子であるか、若しくは一方が置換又は無置換の炭素原子であり、且つ、他方が窒素原子である。 In order to achieve the above object, the water-based ink for inkjet recording of the present invention comprises:
A water-based ink for inkjet recording comprising a colorant, water and a water-soluble organic solvent,
The colorant contains a dye represented by the general formula (1),
The water-based ink further includes a cationic polymer.

In general formula (1),
R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
R ₂ is a hydrogen atom, a halogen atom or a cyano group,
R ₃ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group,
R ₄ , R ₅ , R ₆ and R ₇ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted sulfonyl group. A substituted or unsubstituted acyl group, and R ₄ , R ₅ , R ₆ and R ₇ may be the same or different, but R ₄ and R ₅ are not both hydrogen atoms, and R ₆ and R ₇ is not both a hydrogen atom,
A ₁ and A ₂ are both substituted or unsubstituted carbon atoms, or one is a substituted or unsubstituted carbon atom and the other is a nitrogen atom.

  Since the water-based ink of the present invention contains the dye represented by the general formula (1), the hue is good and the fastness to light, heat, and ozone is excellent. Further, since the aqueous ink of the present invention further contains a cationic polymer, a decrease in optical density (OD value) in a high humidity environment is suppressed.

FIG. 1 is a schematic perspective view showing an example of the configuration of the ink jet recording apparatus of the present invention.

  The water-based ink for inkjet recording of the present invention (hereinafter sometimes referred to as “water-based ink” or “ink”) will be described. The water-based ink of the present invention contains a colorant, water, and a water-soluble organic solvent. As described above, the colorant includes a dye represented by the general formula (1).

As described above, in the general formula (1),
R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
R ₂ is a hydrogen atom, a halogen atom or a cyano group,
R ₃ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group,
R ₄ , R ₅ , R ₆ and R ₇ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted sulfonyl group. A substituted or unsubstituted acyl group, and R ₄ , R ₅ , R ₆ and R ₇ may be the same or different, but R ₄ and R ₅ are not both hydrogen atoms, and R ₆ and R ₇ is not both a hydrogen atom,
A ₁ and A ₂ are both substituted or unsubstituted carbon atoms, or one is a substituted or unsubstituted carbon atom and the other is a nitrogen atom.

  In the general formula (1), the substituted or unsubstituted alkyl group is preferably an alkyl group having 1 to 6 carbon atoms. Examples of the substituted or unsubstituted alkyl group include a methyl group, ethyl group, n-butyl group, isopropyl group, tert-butyl group, hydroxyethyl group, methoxyethyl group, cyanoethyl group, trifluoromethyl group, 3- Examples thereof include a sulfopropyl group and a 4-sulfobutyl group. Examples of the substituent of the substituted alkyl group include hydroxyl group; alkoxy group such as methoxy group and ethoxy group; cyano group; halogen atom such as fluorine atom, chlorine atom, bromine atom and iodine atom; carboxylate salt and sulfonic acid Examples thereof include ionic hydrophilic groups such as salts.

  In the general formula (1), the substituted or unsubstituted aryl group is preferably an aryl group having 6 to 12 carbon atoms. However, in the case of a substituted aryl group, the number of carbon atoms does not include the number of carbon atoms of the substituent. Examples of the substituted or unsubstituted aryl group include phenyl group, naphthyl group, p-tolyl group, p-octylphenyl group, mesityl group, p-methoxyphenyl group, o-chlorophenyl group, m- (3-sulfo group). Propylamino) phenyl group and the like. Examples of the substituent of the substituted aryl group include an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, and an n-octyl group; an alkoxy group similar to the above; a halogen atom similar to the above; Alkylamino groups such as amino groups and dimethylamino groups; Amido groups; Carbamoyl groups; Sulfamoyl groups; Sulfamide groups; Hydroxyl groups; Ester groups such as methoxycarbonyl groups and ethoxycarbonyl groups; It is done.

  In the general formula (1), examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

  In the general formula (1), the substituted or unsubstituted heterocyclic group is preferably a 5-membered or 6-membered heterocyclic group. Examples of the substituted or unsubstituted heterocyclic group include 2-pyridyl group, 2-thienyl group, 2-thiazolyl group, 2-benzothiazolyl group, 2-furyl group, 6-sulfobenzothiazolyl group, 6- Examples thereof include a sulfonate benzothiazolyl group. Examples of the substituent of the substituted heterocyclic group include an amide group; a carbamoyl group; a sulfamoyl group; a sulfoamide group; a hydroxyl group; an ester group as described above; and an ionic hydrophilic group as described above.

  In the general formula (1), examples of the substituted or unsubstituted sulfonyl group include a methylsulfonyl group and a phenylsulfonyl group. Examples of the substituent of the substituted sulfonyl group include the same substituted or unsubstituted alkyl group as described above, and the same substituted or unsubstituted aryl group as described above.

  In the general formula (1), the substituted or unsubstituted acyl group is preferably an acyl group having 1 to 12 carbon atoms. However, in the case of a substituted acyl group, the number of carbon atoms does not include the number of carbon atoms of the substituent. Examples of the substituted or unsubstituted acyl group include an acetyl group, a benzoyl group, and a chloroacetyl group. Examples of the substituent of the substituted acyl group include the same ionic hydrophilic groups as described above.

In the general formula (1), as described above, A ₁ and A ₂ are both substituted or unsubstituted carbon atoms, or one of them is a substituted or unsubstituted carbon atom, and the other is a nitrogen atom. It is. The case where both A ₁ and A ₂ are carbon atoms is preferable in that it can exhibit more excellent performance. Examples of the substituent bonded to the carbon atom of A ₁ and A _2, for example, an alkyl group having 1 to 3 carbon atoms, a carboxy group, a carbamoyl group, a cyano group, and the like.

As described above, in the general formula (1), R ₄ and R ₅ are not both hydrogen atoms, and R ₆ and R ₇ are not both hydrogen atoms. Moreover, in General formula (1), when the substitution number of a sulfonic acid group or a carboxy group increases, the water solubility of the dye tends to be improved. Therefore, it is preferable to adjust the substitution number as necessary.

As a preferable embodiment of the dye represented by the general formula (1), for example, in the general formula (1), R ₁ is an alkyl group, R ₂ is a cyano group, R ₃ is a hydrogen atom or a substituted or unsubstituted heterocyclic group. , R ₄ is a hydrogen atom, a substituted or unsubstituted heterocyclic group or substituted aryl group, R ₅ and R ₆ are each a substituted heterocyclic group or a substituted aryl group, R ₇ is a hydrogen atom, and A ₁ is substituted And the carbon atom A ₂ is a substituted or unsubstituted carbon atom.

As a more preferable embodiment of the dye represented by the general formula (1), for example, in the general formula (1), R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ is a hydrogen atom or a sulfonic acid group or a group thereof. Benzothiazolyl group (preferably benzothiazol-2-yl group) optionally substituted with an alkali metal base, R ₄ is a hydrogen atom, a sulfonic acid group or a benzothiazolyl group optionally substituted with an alkali metal base (preferably, A benzothiazol-2-yl group) or a trialkylphenyl group (preferably a mesityl group) substituted with a sulfonic acid group or an alkali metal base thereof, and R ₅ and R ₆ are a sulfonic acid group or an alkali metal thereof, respectively. Mono-, di- or trialkylphenyl groups (preferably p-octyl) Benzothiazolyl group (preferably substituted with Eniru group or mesityl group) or a sulfonic acid group or an alkali metal base, benzothiazol-2-yl group), R ₇ is a hydrogen atom, A ₁ is substituted In this embodiment, the carbon atom and A ₂ are carbon atoms that may be substituted with a cyano group.

  Preferable specific examples of the dye represented by the general formula (1) include compounds represented by the chemical formulas (1-A) to (1-F).

The compound represented by the chemical formula (1-A) is represented by the general formula (1), in which R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ is a benzothiazol-2-yl group, and R ₄ is a hydrogen atom. , R ₅ and R ₆ are each a p-octylphenyl group, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom substituted with a cyano group It is a certain aspect.

In the compound represented by the chemical formula (1-B), R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are each a benzothiazol-2-yl group in the general formula (1) , R ₅ and R ₆ are each a mesityl group, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom.

The compound represented by the chemical formula (1-C) is represented by the general formula (1), in which R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are 6-sulfo sodium salt benzothiazole, respectively. 2-yl group, R ₅ and R ₆ are each a 3-sulfosodium salt mesityl group, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom It is a certain aspect.

The compound represented by the chemical formula (1-D) is represented by the general formula (1), in which R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are 6-sulfolithium salt benzothiazole, respectively. 2-yl group, R ₅ and R ₆ are each 2,6-diethyl-4-methyl-3-sulfolithium phenyl group, R ₇ is a hydrogen atom, and A ₁ is substituted with a methyl group In this embodiment, A ₂ is a carbon atom.

The compound represented by the chemical formula (1-E) is represented by the general formula (1), in which R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are each a 6-sulfo potassium salt benzothiazole. 2-yl group, R ₅ and R ₆ are each a 3-sulfo potassium salt mesityl group, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, and A ₂ is a carbon atom It is a certain aspect.

The compound represented by the chemical formula (1-F) is represented by the general formula (1), in which R ₁ is a tert-butyl group, R ₂ is a cyano group, R ₃ and R ₄ are 6-sulfolithium salts benzothiazole-2- An yl group, R ₅ and R ₆ are 2,6-diethyl-4-sulfolithium phenyl groups, R ₇ is a hydrogen atom, A ₁ is a carbon atom substituted with a methyl group, A ₂ is a carbon atom It is a certain aspect.

  The blending amount of the dye represented by the general formula (1) with respect to the total amount of the water-based ink is not particularly limited. By including the dye represented by the general formula (1), a water-based ink having a good hue and excellent fastness to light, heat, and ozone can be obtained. The blending amount of the dye represented by the general formula (1) with respect to the total amount of the water-based ink is, for example, 0.1 wt% to 10 wt%, preferably 0.5 wt% to 8 wt%, and more preferably. Is 1% to 6% by weight.

  In addition to the dye represented by the general formula (1), the colorant may further contain other dyes and pigments. The pigment is not particularly limited, and for example, carbon black, inorganic pigment, organic pigment, and the like can be used. When the pigment is used, it is preferable to use a dispersant in combination.

  The water is preferably ion exchange water or pure water. The blending amount (water ratio) of the water with respect to the total amount of the water-based ink is, for example, 10% by weight to 90% by weight, and preferably 40% by weight to 80% by weight. The said water ratio is good also as the remainder of another component, for example.

  Examples of the water-soluble organic solvent include a wetting agent that prevents drying of the water-based ink at the nozzle tip of the ink jet head and a penetrating agent that adjusts the drying speed on the recording medium.

  The wetting agent is not particularly limited, and examples thereof include lower alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol; dimethylformamide, dimethylacetamide Amides such as acetone; Ketones such as acetone; Keto alcohols such as diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyhydric alcohols such as polyalkylene glycol, alkylene glycol, glycerin and trimethylolpropane; 2-pyrrolidone; N-methyl- 2-pyrrolidone; 1,3-dimethyl-2-imidazolidinone and the like. Examples of the polyalkylene glycol include polyethylene glycol and polypropylene glycol. Examples of the alkylene glycol include ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, thiodiglycol, and hexylene glycol. These wetting agents may be used alone or in combination of two or more. Among these, polyhydric alcohols such as alkylene glycol and glycerin are preferable.

  The blending amount of the wetting agent with respect to the total amount of the water-based ink is, for example, 0% by weight to 95% by weight, preferably 5% by weight to 80% by weight, and more preferably 5% by weight to 50% by weight. is there.

  Examples of the penetrant include glycol ether. Examples of the glycol ether include ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol-n-propyl ether, diethylene glycol-n-butyl ether, diethylene glycol-n- Hexyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol-n-propyl ether, triethylene glycol-n-butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol-n-propyl ether, Propylene glycol-n-butyl ether , Dipropylene glycol methyl ether, dipropylene glycol ethyl ether, dipropylene glycol-n-propyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol methyl ether, tripropylene glycol ethyl ether, tripropylene glycol-n-propyl ether And tripropylene glycol-n-butyl ether. The said penetrant may be used individually by 1 type, and may use 2 or more types together.

  The blending amount of the penetrant with respect to the total amount of the water-based ink is, for example, 0% by weight to 20% by weight, preferably 0.1% by weight to 15% by weight, and more preferably 0.5% by weight to 10% by weight.

  As described above, the water-based ink further includes a cationic polymer. By including a cationic polymer, it is presumed that a decrease in optical density (OD value) in a high humidity environment is suppressed. In particular, when glossy paper is used as the recording medium, the effect of sealing by the interaction of the silica particles on the glossy paper and the cationic polymer works, and the change in the ease of diffusion of dyes on glossy paper due to humidity (migration) changes. As a result, it is estimated that the decrease in optical density (OD value) is suppressed, but the present invention is not limited to this estimation.

The cationic polymer includes a compound represented by general formula (2), a compound represented by general formula (3), a compound represented by general formula (4), and a compound represented by general formula (5) (polyethyleneimine). Preferably it is at least one compound.

  In General formula (2), m is an integer of 2-6 and n is an integer of 20-40.

  In general formula (2), m is particularly preferably 4. In this case, the compound represented by the general formula (2) is polylysine. Moreover, in General formula (2), it is preferable that n is 25-35.

  The compound represented by the general formula (2) may include a derivative of the compound represented by the general formula (2). In the case where the compound represented by the general formula (2) and the derivative thereof include isomers such as tautomers or stereoisomers (eg, geometric isomers, conformers and stereoisomers), any These isomers can also be used in the present invention. Moreover, the salt of the compound represented by General formula (2) and its derivative (s) can be used for this invention similarly. The salt may be an acid addition salt or a base addition salt. Furthermore, the acid forming the acid addition salt may be an inorganic acid or an organic acid, and the base forming the base addition salt may be an inorganic base or an organic base. The inorganic acid is not particularly limited. For example, hydrochloric acid, sulfuric acid, phosphoric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, hypofluorite, hypochlorous acid, hypobromite, Hypoiodous acid, fluorinated acid, chlorous acid, bromic acid, iodic acid, fluoric acid, chloric acid, bromic acid, iodic acid, perfluoric acid, perchloric acid, perbromic acid, periodic acid, etc. can give. The organic acid is not particularly limited. For example, glutamic acid, p-toluenesulfonic acid, methanesulfonic acid, oxalic acid, p-bromobenzenesulfonic acid, carbonic acid, succinic acid, citric acid, benzoic acid, acetic acid, hydroxycarboxylic acid Propionic acid, malonic acid, adipic acid, fumaric acid, maleic acid and the like. Examples of the inorganic base include, but are not limited to, ammonium hydroxide, alkali metal hydroxide, alkaline earth metal hydroxide, carbonate, bicarbonate, sulfate, and the like. More specifically, Examples thereof include sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydroxide, calcium carbonate, potassium sulfate, calcium sulfate and the like. The organic base is not particularly limited, and examples thereof include alcohol amine, trialkylamine, tetraalkylammonium, and tris (hydroxymethyl) aminomethane. Examples of the alcohol amine include ethanolamine. Examples of the trialkylamine include trimethylamine, triethylamine, tripropylamine, tributylamine, and trioctylamine. Examples of the tetraalkylammonium include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, tetraoctylammonium and the like.

In General formula (3) and (4), R < ₁₁ > -R < ₁₃ > is a hydrogen atom or an organic group, respectively. Examples of the organic group include an alkyl group and an aryl group. The alkyl group may be linear or branched. For example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-hexyl group. Group, cyclohexyl group, n-octyl group, 2-ethylhexyl group, n-decyl group, n-dodecyl group, octadecyl group, 1,3-butadienyl group, 1,3-pentadienyl group and the like. Examples of the aryl group include a phenyl group, a naphthyl group, a tolyl group, and a vinylphenyl group. The alkyl group and aryl group may have a substituent. Examples of the alkyl group and aryl group having the substituent include, for example, a fluoroethyl group, a trifluoroethyl group, a methoxyethyl group, a phenoxyethyl group, a hydroxyphenylmethyl group, a chlorophenyl group, a dichlorophenyl group, a trichlorophenyl group, a bromophenyl group, Examples include iodophenyl group, fluorophenyl group, hydroxyphenyl group, methoxyphenyl group, cetoxyphenyl group, cyanophenyl group and the like.

In the general formula (4), X ⁻ is an anion. The anion may be any one, and examples thereof include halide ions, sulfonate ions, alkyl sulfonate ions, aryl sulfonate ions, alkyl carboxylate ions, and aryl carboxylate ions.

  In General Formula (3) and (4), p is a positive integer, for example, 10 to 400, preferably 15 to 300, and more preferably 20 to 200. The weight average molecular weight of the compounds represented by the general formulas (3) and (4) is not particularly limited, but is, for example, 600 to 20000, preferably 900 to 15000, and more preferably 1200 to 10,000. .

In the general formula (3), R ₁₁ and R ₁₂ are particularly preferably hydrogen atoms. In this case, the compound represented by the general formula (3) is polyallylamine. Moreover, in General formula (4), it is preferable that R < ₁₁ > -R < ₁₃ > is a hydrogen atom and X < ^- > is a chloride ion. In this case, the compound represented by the general formula (4) is polyallylamine hydrochloride (allylamine hydrochloride polymer).

  In General formula (5), q is a positive integer, for example, is 12 to 500, preferably 20 to 350, and more preferably 28 to 250. The general formula (5) shows a linear polyethyleneimine, but the cationic polymer is a polyethyleneimine having a branched chain structure such as containing a primary, secondary or tertiary amine. May be.

Examples of the cationic polymer include compounds other than the compound represented by the general formula (2), the compound represented by the general formula (3), the compound represented by the general formula (4), and the compound represented by the general formula (5). It may be used. Examples of the cationic polymer other than the compound represented by the general formula (2), the compound represented by the general formula (3), the compound represented by the general formula (4), and the compound represented by the general formula (5) include: , Polyamine, polyvinylamine, polyvinylpyridine, polyethyleneimine-epichlorohydrin reactant, polyamide-polyamine resin, polyamide-epichlorohydrin resin, cationic starch, polyvinyl alcohol, polyvinylpyrrolidone, polyamidine, cationic epoxy resin, polyacrylamide, polyacrylic ester, poly Methacrylic acid ester, polyvinylformamide, aminoacetalized polyvinyl alcohol, polyvinylbenzylonium, dicyandiamide / formalin polycondensate, dicyandiamide / diethylenetriami Polycondensates, epichlorohydrin-dimethylamine addition polymer, dimethyldiallylammonium chloride-SO ₂ copolymer, dimethyl diallyl ammonium chloride polymer, and derivatives thereof. The cationic polymer other than the compound represented by the general formula (2), the compound represented by the general formula (3), the compound represented by the general formula (4), and the compound represented by the general formula (5) For example, dimethylaminoethyl-methacrylate (DM), methacryloyloxyethyl-trimethylammonium chloride (DMC), methacryloyloxyethyl-benzyldimethyl-ammonium chloride (DMBC), dimethylaminoethyl-acrylate (DA), acryloyl Roxyethyl-trimethylammonium chloride (DMQ), acryloyloxyethyl-benzyldimethyl-ammonium chloride (DABC), dimethylaminopropyl-acrylamide (DMAPAA), acrylamidopropyl-trimethylammoni Beam - a copolymer of a single monomer polymers or more monomers comprising at least one water-soluble monomer such as chloride (DMAPAAQ) may be mentioned.

  The cationic polymer may be prepared in-house or a commercially available product may be used. Examples of the commercially available products include polylysine manufactured by Chisso Corporation, “PAA (registered trademark) -01”, “PAA (registered trademark) -03”, and “PAA (registered trademark) − manufactured by Nitto Boseki Co., Ltd. 08 ”,“ PAA (registered trademark) -15 ”, and polyethyleneimine manufactured by Junsei Chemical Co., Ltd.

  The weight average molecular weight of the cationic polymer is, for example, 600 to 20000, preferably 900 to 15000, and more preferably 1200 to 10,000. The blending amount of the cationic polymer with respect to the total amount of the aqueous ink is, for example, 0.2 wt% to 6 wt%, preferably 0.5 wt% to 4.5 wt%, more preferably 1% to 3% by weight. It is particularly preferable that the weight average molecular weight of the cationic polymer is 1200 or more, and the blending amount of the cationic polymer with respect to the total amount of the water-based ink is 0.5% by weight or more. The cationic polymer may be used alone or in combination of two or more.

  The water-based ink may further contain a conventionally known additive as required. Examples of the additive include a surfactant, a pH adjuster, a viscosity adjuster, a surface tension adjuster, and an antifungal agent. Examples of the viscosity modifier include polyvinyl alcohol, cellulose, and a water-soluble resin.

  The water-based ink is, for example, a colorant, water, a water-soluble organic solvent, the cationic polymer, and other additive components as necessary, which are uniformly mixed by a conventionally known method, and insoluble in a filter or the like. Can be prepared by removing.

  The aqueous ink of the present invention can be used as, for example, an aqueous magenta ink. However, the present invention is not limited to this. The water-based ink of the present invention can be a water-based ink having a color other than magenta by using a colorant other than the dye represented by the general formula (1).

  Next, the ink cartridge of the present invention will be described. The ink cartridge of the present invention is an ink cartridge containing a water-based ink for ink-jet recording, and the water-based ink is the water-based ink for ink-jet recording of the present invention. As the main body of the ink cartridge, for example, a conventionally known one can be used.

  Next, the ink jet recording apparatus of the present invention and the ink jet recording method using the same will be described. The recording includes printing, printing, printing, and the like.

  The ink jet recording apparatus of the present invention is an ink jet recording apparatus that includes an ink storage portion and an ink discharge means, and discharges ink stored in the ink storage portion by the ink discharge means. The water-based ink for inkjet recording is accommodated.

  FIG. 1 shows the configuration of an example of the ink jet recording apparatus of the present invention. As shown in the figure, this ink jet recording apparatus 1 includes four ink cartridges 2, an ink discharge means (ink jet head) 3, a head unit 4, a carriage 5, a drive unit 6, a platen roller 7, and a purge device 8. And as a major component.

  The four ink cartridges 2 contain one color each of four colors of water-based inks of yellow, magenta, cyan, and black. For example, the water-based magenta ink is the water-based ink for inkjet recording of the present invention. Other water-based inks may be general water-based inks. The ink jet head 3 installed in the head unit 4 performs recording on a recording medium (for example, recording paper (preferably glossy paper, more preferably glossy paper having a void type resin coat layer)) P. Four ink cartridges 2 and a head unit 4 are mounted on the carriage 5. The drive unit 6 reciprocates the carriage 5 in the linear direction. As the drive unit 6, for example, a conventionally known one can be used (for example, see Japanese Patent Application Laid-Open No. 2008-246821). The platen roller 7 extends in the reciprocating direction of the carriage 5 and is disposed to face the inkjet head 3.

  The purge device 8 sucks out defective ink containing bubbles and the like accumulated in the ink jet head 3. As the purge device 8, for example, a conventionally known device can be used (see, for example, JP-A-2008-246821).

  A wiper member 20 is disposed adjacent to the purge device 8 on the platen roller 7 side of the purge device 8. The wiper member 20 is formed in a spatula shape, and wipes the nozzle formation surface of the inkjet head 3 as the carriage 5 moves. In FIG. 1, a cap 18 covers a plurality of nozzles of the inkjet head 3 that is returned to the reset position when recording is completed in order to prevent the water-based ink from drying.

  In the ink jet recording apparatus 1 of this example, four ink cartridges 2 are mounted on one carriage 5 together with the head unit 4. However, the present invention is not limited to this. In the ink jet recording apparatus, each of the four ink cartridges 2 may be mounted on a carriage different from the head unit 4. Further, each of the four ink cartridges 2 may not be mounted on the carriage 5 but may be arranged and fixed in the ink jet recording apparatus. In these aspects, for example, each cartridge of the four ink cartridges 2 and the head unit 4 mounted on the carriage 5 are connected by a tube or the like, and each cartridge of the four ink cartridges 2 is connected to the head unit 4 from the cartridge. Aqueous ink is supplied.

  Ink jet recording using this ink jet recording apparatus 1 is performed as follows, for example. First, the recording paper P is fed from a paper feed cassette (not shown) provided on the side of or below the ink jet recording apparatus 1. The recording paper P is introduced between the inkjet head 3 and the platen roller 7. Predetermined recording is performed on the introduced recording paper P by water-based ink ejected from the inkjet head 3. By using the water-based ink of the present invention, it is possible to obtain a recorded matter having a good hue, excellent fastness to light, heat and ozone, and suppressing a decrease in optical density (OD value) in a high humidity environment. it can. The recording sheet P after recording is discharged from the inkjet recording apparatus 1. In FIG. 1, the paper feed mechanism and paper discharge mechanism for the recording paper P are not shown.

  The apparatus shown in FIG. 1 employs a serial type ink jet head, but the present invention is not limited to this. The inkjet recording apparatus may be an apparatus that employs a line-type inkjet head.

  According to the present invention, there is provided an ink jet recording method for performing recording by ejecting ink from an ink ejecting means, wherein the water-based ink for ink jet recording of the present invention is used as the ink. The The ink jet recording method can be performed using, for example, the ink jet recording apparatus of the present invention.

Next, examples of the present invention will be described together with comparative examples. In addition, this invention is not limited and restrict | limited by the following Example and comparative example.

[Examples 1 to 10 and Comparative Examples 1 to 4]
Each component of the aqueous ink composition (Table 1) was mixed uniformly. Thereafter, the obtained mixture was filtered using a hydrophilic polytetrafluoroethylene (PTFE) type membrane filter (pore diameter 0.20 μm) manufactured by Toyo Roshi Kaisha, Ltd., so that Examples 1 to 10 and Comparative Example 1 were used. -4 water-based inks for inkjet recording were obtained. In Table 1, dyes (1-A) to (1-E) are compounds represented by chemical formulas (1-A) to (1-E), respectively.

  The optical density (OD value) difference (ΔOD) evaluation of the water-based inks of Examples and Comparative Examples was performed by the following method. Using a digital multifunction printer DCP-385C equipped with an inkjet printer manufactured by Brother Industries, Ltd., using the water-based inks of Examples and Comparative Examples, “Special Paper (Photo Glossy Paper) (BP” manufactured by Brother Industries, Ltd.) -71) "(glossy paper A) For the magenta patch recorded, the optical density (OD value) difference (ΔOD) was calculated by the following method. For Example 1 and Comparative Example 1, comparison was made on “Photo Paper Crispier <High Gloss>” (Glossy Paper B) and “Photo Paper <Glossy” ”(Glossy Paper C) manufactured by Seiko Epson Corporation. The optical density (OD value) difference (ΔOD) was similarly calculated for the magenta patch recorded on the glossy paper B for Example 2 and on the glossy paper C for Comparative Example 3.

The magenta patch was recorded in an environment of normal temperature and normal humidity (temperature of 25 ° C., relative humidity of 50%), and stored for 24 hours in the same environment as the recording, to obtain a normal temperature and normal humidity environment sample. Further, the magenta patch was recorded in an environment of low temperature and high humidity (temperature 18 ° C., relative humidity 80%), and stored in the same environment as that of the recording to obtain a low temperature and high humidity environment sample. The optical density (OD value) of the normal temperature and normal humidity environment sample and the low temperature and high humidity environment sample was measured using a spectrocolorimeter Spectrolino (built-in filter: none (No); Density standard: ANSI T; density filter; automatic), and the optical density (OD value) difference (ΔOD) between two environments of normal temperature and normal humidity and low temperature and high humidity was calculated by the following formula. The optical density (OD value) difference (ΔOD) was evaluated according to the following evaluation criteria.

ΔOD = | OD ₁ −OD ₂ |
OD ₁ : Optical density (OD value) of the magenta patch of the low temperature and high humidity environment sample
OD ₂ : Optical density (OD value) of the magenta patch of the normal temperature and humidity environment sample

Evaluation of optical density (OD value) difference Evaluation criteria A: The optical density (OD value) difference (ΔOD) is less than 0.08 B: The optical density (OD value) difference (ΔOD) is 0.08 or more and 0.12. Less than C: the optical density (OD value) difference (ΔOD) is 0.12 or more

  Table 1 shows the aqueous ink compositions and evaluation results of the aqueous inks of Examples and Comparative Examples.

  As shown in Table 1, in Examples 1 to 10, the decrease in the optical density (OD value) of the magenta patch in a low temperature and high humidity environment was suppressed. Examples 1 to 6, 8 and 9 in which a cationic polymer having a weight average molecular weight of 1200 or more was used, and the blending amount of the cationic polymer with respect to the total amount of the water-based ink was 0.5% by weight or more and 2.5% by weight or less. However, the decrease in the optical density (OD value) of the magenta patch in a low temperature and high humidity environment was further suppressed. On the other hand, in Comparative Example 1 in which no cationic polymer was used, the sealing effect was not exhibited, and the optical density (OD value) of the magenta patch was lowered in a low temperature and high humidity environment. In addition, in Comparative Examples 2 to 4 using polyvinyl pyrrolidone which is a non-cationic polymer, or lysine hydrochloride and dimethylethyloctylammonium ethylsulfuric acid which are non-cationic polymers instead of the cationic polymer, the sealing effect is also obtained. The optical density (OD value) of the magenta patch was reduced in a low temperature and high humidity environment.

  As described above, the aqueous ink of the present invention has a good hue, excellent fastness to light, heat, and ozone, and suppresses a decrease in optical density (OD value) in a high humidity environment. The use of the water-based ink of the present invention is not particularly limited, and can be widely applied to various ink jet recordings.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 Ink cartridge 3 Ink discharge means (inkjet head)
4 Head unit 5 Carriage 6 Drive unit 7 Platen roller 8 Purge device

Claims (4)

A water-based ink for inkjet recording comprising a colorant, water and a water-soluble organic solvent,
The colorant contains a dye represented by the general formula (1),
The water-based ink for ink jet recording, wherein the water-based ink further contains a cationic polymer.

In general formula (1),
R ₁ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group,
R ₂ is a hydrogen atom, a halogen atom or a cyano group,
R ₃ is a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group,
R ₄ , R ₅ , R ₆ and R ₇ are each a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted or unsubstituted sulfonyl group. A substituted or unsubstituted acyl group, and R ₄ , R ₅ , R ₆ and R ₇ may be the same or different, but R ₄ and R ₅ are not both hydrogen atoms, and R ₆ and R ₇ is not both a hydrogen atom,
A ₁ and A ₂ are both substituted or unsubstituted carbon atoms, or one is a substituted or unsubstituted carbon atom and the other is a nitrogen atom. The aqueous ink for inkjet recording according to claim 1, wherein the cationic polymer contains at least one selected from the group consisting of polylysine, polyallylamine, and polyethyleneimine. The water-based ink for ink-jet recording according to claim 1 or 2, wherein the weight average molecular weight of the cationic polymer is 1200 or more, and the amount of the cationic polymer based on the total amount of the water-based ink is 0.5% by weight or more. An ink cartridge comprising a water-based ink for ink-jet recording, wherein the water-based ink is the water-based ink for ink-jet recording according to any one of claims 1 to 3.

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