JP2001323192A - Inkjet water-based pigment ink and ink-jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet water-based pigment ink and an ink-jet recording method which have excellent storage stability and discharge stability of the ink and, can afford high-gloss images on an inkjet gloss medium. SOLUTION: The inkjet water-based pigment ink comprises a water-soluble photocurable monomer and/or oligomer having two or more functional groups which is a compound having a group to be represented by the formula: -(X)m-(C =O)-Y-, wherein X and Y are each an oxygen atom or a nitrogen atom; and m is 0 or 1 and a pigment in an aqueous medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet pigment ink and an ink-jet recording method, and more particularly to an aqueous ink-jet pigment ink and an ink-jet recording method using the pigment ink. More specifically, the present invention relates to a water-based pigment ink for ink-jet, which can provide a high gloss image on a glossy medium for ink-jet, and has excellent storage stability and ejection stability, and an ink-jet recording method using the pigment ink.

[0002]

2. Description of the Related Art The ink jet recording method is capable of recording a high-definition image with a relatively simple apparatus, and has been rapidly developing in various fields. Has been manufactured.
In addition, there are a wide variety of ink types depending on the intended use. For example, as an ink for an application requiring an image that is resistant to fading due to light, a pigment ink using a pigment having relatively good light resistance as compared with a dye as a coloring agent is used. However, when these pigment inks are used to record on media having a high surface gloss such as generally referred to as glossy paper for inkjet or glossy film for inkjet, the fixability to the media tends to be inferior to that of the dye ink. In many cases, the water resistance of the image is insufficient or the abrasion resistance is insufficient. This is because, in order to express high gloss in media with high surface gloss, the size of the hole opened on the media surface is designed to be smaller than that of plain paper or coated paper. It is considered that one of the major factors is that the pigment particles are smaller than the average particle diameter and most of the pigment particles are fixed to the outside of the surface of the medium.

Therefore, various technical means have been devised for pigment inks in terms of glossiness, scratch resistance and water resistance.
For example, JP-A-8-31383 discloses a neutralized product of an alkali-soluble resin having a pigment having an average particle diameter of 0.3 μm or less in an amount of 1 to 10% by weight and a weight average molecular weight of 20,000 or less which is three times or more of the pigment. Is added to the aqueous ink to improve the water resistance and scratch resistance of the image. However, due to the high resin content in this method,
There is a problem that the viscosity of the ink as a whole increases, high energy is required at the time of ejection, and in some cases, it is difficult to stably eject the ink, and clogging in the head easily occurs. . In addition, Tokiko Sho 6
JP-A-0-32663 and JP-A-4-18462 describe that a latex is contained in an ink to improve water resistance and abrasion resistance. However, in this method, if an amount of latex sufficient for exhibiting water resistance and abrasion resistance is added to the ink even in a medium having a high surface gloss, the storage stability of the ink is reduced, and the clogging of the nozzle portion of the head or the like may occur. There has been a problem that ejection failure is likely to occur due to clogging of the filter portion.

Japanese Patent Application Laid-Open (JP-A) Nos. 3-216379 and 8-48922 disclose a technique for incorporating a photocurable monomer / oligomer into an ink. The ink tends to be clogged, and has a problem in the storage stability of the ink. JP-A-2-311569, JP-A-5-186
JP-A-725-225 and JP-A-7-224241 describe a technique in which a water-soluble photocurable monomer / oligomer is contained in an ink, and attempts have been made to improve bleeding prevention and the like. It is difficult to improve the glossiness of the image area only by adding the ink to the ink.

As described above, it is difficult to improve the glossiness of the pigment ink by the conventional method, and at the same time, there is a problem that the storage stability of the ink, the clogging of the nozzles, the discharge stability and the like are easily caused. Was. In addition, when recording on a medium having a high surface glossiness, it is required that the image quality, especially the glossiness, is high and there is no difference in gloss from the non-printed portion (white background), in addition to water resistance and scratch resistance. However, as described above, when recording on glossy paper or a glossy film using a pigment ink, most of the pigment is fixed on the surface of the medium, so that the texture tends to be worse than that of the dye ink. Furthermore, there is a problem that the technology applied to the ink to increase the water resistance and the abrasion resistance tends to further deteriorate the texture.

[0006]

Accordingly, the first aspect of the present invention is as follows.
It is an object of the present invention to provide an aqueous pigment ink for inkjet which is excellent in storage stability and ejection stability of the ink and can obtain an image having a high gloss level on a glossy medium for inkjet. A second object of the present invention is to
An object of the present invention is to provide an ink jet recording method which is excellent in storage stability and ejection stability of an ink and can obtain an image having high glossiness on a glossy medium for ink jet.

[0007]

The object of the present invention is to provide: (1) an aqueous pigment ink containing a water-soluble photocurable monomer and / or oligomer containing two or more functional groups in an aqueous medium and a pigment; Wherein the water-soluble photocurable monomer or oligomer containing two or more is a compound having a group represented by the following formula: -(X) m- (C = O) -Y- (Formula) (wherein, X and Y represent an oxygen atom or a nitrogen atom;
Represents 0 or 1. (2) The aqueous pigment ink for inkjet according to the above (1), wherein the water-soluble photocurable monomer or oligomer is a water-soluble photocurable monomer or oligomer having a urethane group or an ester group in the molecule. (3) The aqueous pigment for inkjet according to the above (1) or (2), wherein the water-soluble photocurable monomer or oligomer is a water-soluble photocurable monomer or oligomer having a weight average molecular weight of 1,000 to 50,000. ink. (4) On the recording medium having the void type image receiving layer, the above (1)
An inkjet recording method, comprising: ejecting the aqueous pigment ink for inkjet according to any one of (1) to (3) to form an image. Achieved by

Hereinafter, the present invention will be described in detail. First, the water-soluble photocurable monomer and oligomer containing two or more functional groups of the present invention will be described.

The water-soluble photocurable monomer or oligomer having two or more functional groups of the present invention is a compound having a group represented by the following formula (hereinafter sometimes referred to as “group of the present invention”). . -(X) m- (C = O) -Y- (Formula) (wherein, X and Y represent an oxygen atom or a nitrogen atom;
Represents 0 or 1. ) Water-soluble photocurable monomers and oligomers containing two or more functional groups of the present invention (hereinafter, referred to as
It may also be referred to as "the water-soluble photocurable monomer and oligomer of the present invention". )), As the functional group, for example, acryloyl group, methacryloyl group, acrylic group,
Examples include a methacryl group, an allyl group, and a vinyl group.

The two or more functional groups contained in the water-soluble photocurable monomer and oligomer of the present invention may be the same or different. The group of the present invention contained in the water-soluble photocurable monomer and oligomer of the present invention is preferably a urethane group or an ester group. In the present invention,
Water-soluble means that the aqueous ink dissolves at room temperature.

The weight average molecular weight of the water-soluble photocurable monomer and oligomer of the present invention is preferably from 1,000 to 50,000. The weight average molecular weight referred to here is GPC (gel permeation chromatography)
And calculated in terms of polystyrene. If the weight average molecular weight is 1000 or less, the glossiness of the image is not sufficient, and if the weight average molecular weight is 50,000 or more,
The viscosity increases, and the ejection stability becomes slightly insufficient.

In the aqueous pigment ink for inkjet, the water-soluble photocurable monomer and oligomer of the present invention is preferably used in an amount of 0.1% by weight or more and 20% by weight or less based on the total weight of the ink, and 0.5% by weight or less. It is particularly preferable to use at least 10% by weight. If the addition amount is less than 0.1% by weight, it is difficult to exert a sufficient effect on the glossiness, and if it exceeds 20% by weight, the ink viscosity increases and the pigment dispersion particle diameter tends to increase with time, so that the ink is stored. Problems often arise in terms of gender.

Specific examples of the water-soluble photocurable monomer and oligomer of the present invention which can be used in the present invention include:
The following can be mentioned, but the water-soluble photocurable monomer and oligomer of the present invention are not limited thereto. (1) Polyurethane monomers and oligomers having (meth) acrylate groups (for example, UA manufactured by Kyoei Chemical Co., Ltd.)
-R1, WS-12, UA-720 manufactured by Shin-Nakamura Chemical Co., Ltd.
0, UA-W2A, Daiichi Kogyo Seiyaku GX-8507) (2) Polyester monomers and oligomers having a (meth) acrylate group (for example, T
O-1321, TO-1343)

In the present invention, a photopolymerization initiator can be used, if necessary. The photopolymerization initiator may be added to the aqueous pigment ink for inkjet of the present invention, or even if mixed on a recording medium, before, during, and after forming an image with the aqueous pigment ink for inkjet, It may be applied. As the photopolymerization initiator, a known photopolymerization initiator can be used. After an image is formed using the aqueous pigment ink for inkjet of the invention, the ink may be cured by light irradiation.

In the present invention, conventionally known organic and inorganic pigments can be used as the pigment. Examples of the pigment that can be used in the present invention include, for example, azo pigments, insoluble azo pigments, azo pigments such as condensation azo pigments, chelating azo pigments, phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, Polycyclic pigments such as thioindigo pigments, isoindolinone pigments, quinophthaloni pigments, dye lakes such as basic dye lakes and acid dye lakes,
Organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments, and inorganic pigments such as carbon black. Even pigments not described in the color index can be used as long as they can be dispersed in water.

In the ink jet aqueous pigment of the present invention, a pigment dispersant can be used for dispersing the pigment. Examples of the pigment dispersant that can be used in the present invention include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, and polyoxygens. Activator such as alkylene alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinylnaphthalene Block copolymers composed of two or more monomers selected from derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, and fumaric acid derivatives; Copolymer and can be exemplified salts thereof. The method of dispersing the pigment in the aqueous pigment ink for inkjet of the present invention, for example, ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, etc. These can be used alone or in appropriate combination.

The particle size of the pigment dispersion used in the present invention is as follows:
The average particle size is preferably from 10 nm to 500 nm, more preferably from 10 nm to 200 nm.
If the average particle size of the pigment dispersion exceeds 500 nm, the glossiness of the image recorded on the glossy media is significantly deteriorated,
Significant deterioration of transparency occurs. Further, there is a problem that clogging is likely to occur in terms of ink dischargeability. If the average particle size of the pigment dispersion is less than 10 nm, the stability of the pigment dispersion is likely to deteriorate, and the storage stability of the ink is likely to deteriorate.

The particle size of the pigment dispersion can be determined by a commercially available particle size measuring device using a light scattering method, an electrophoresis method, a laser Doppler method or the like. In preparing the ink, it is preferable to mix (mix and stir) the pigment in the form of an aqueous dispersion (solid content of 5 to 50% by weight) with another ink composition from the viewpoint of the dispersion stability of the pigment.

The ink of the present invention may contain a water-soluble organic solvent, if necessary. Preferred water-soluble organic solvents include, for example, alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.) Alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol,
Polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, etc., polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl) Ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, triethylene glycol monomethyl ether, triethylene glycol Bruno ethyl ether, triethylene glycol monobutyl ether, ethylene glycol monophenyl ether, propylene glycol monophenyl ether), amines (e.g., ethanolamine, diethanolamine, triethanolamine, N-
Methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine,
Pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocycles (eg, 2-pyrrolidone, N-methyl-2- Pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-
Imidazolidinone), sulfoxides (eg, dimethyl sulfoxide), sulfones (eg, sulfolane), urea, acetonitrile, acetone and the like.

The aqueous pigment ink for inkjet of the present invention may contain a surfactant, if necessary. Examples of the surfactant preferably used include, for example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, and acetylene glycol. , Nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used. Further, the dispersant for pigment described above may be added to the ink.

Further, to the aqueous pigment ink for inkjet of the present invention, a viscosity modifier can be added for the purpose of adjusting the viscosity, and a resin (polymer) can be added for the purpose of improving the water resistance of the printed portion. Examples of the polymer include natural water-soluble polymers such as corn and starch such as wheat, cellulose derivatives such as carboxymethylcellulose, methylcellulose and hydroxyethylcellulose, sodium alginate, guar gum, tamarind gum, locust bean gum, gum arabic and the like. Sugars, gelatin, casein,
Protein substances such as keratin, synthetic water-soluble polymers such as polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, and acrylic acid polymers can be used. Further, a polymer in a state where the polymer is dispersed in water may be added. Examples of the polymer which is dispersed in water include styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, and acrylate ester copolymer. Examples include a polymer, polyurethane, a silicone-acrylic copolymer, and an acrylic-modified fluororesin.

The water-based pigment ink for ink-jet recording of the present invention may further contain a preservative, a fungicide, an antifoaming agent, a pH adjuster, and the like, if necessary. The water-based inkjet pigment ink of the present invention is mainly composed of the components described above. The physical properties of the ink include adjusting the viscosity of the ink from 2 to 20 cp by adjusting the components and the amounts thereof.
(25 ° C.), and the surface tension is preferably 25 to 60 mN / m.

The ink jet head used in the ink jet recording method of the present invention may be of an on-demand type or a continuous type. In addition, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shared mode type, a shared wall type, etc.), and an electro-thermal conversion method (for example, thermal Inkjet type,
Specific examples include a bubble jet (registered trademark) type, an electrostatic suction type (eg, an electric field control type, a slit jet type, etc.), and a discharge type (eg, a spark jet type, etc.). Either ejection method may be used.

Although the aqueous pigment ink for inkjet of the present invention can be recorded on various media, it is advantageous in terms of glossiness to record on media having a high surface gloss such as inkjet paper and glossy paper. Further, it is preferable to record on a recording medium having a void type image receiving layer.

Here, a recording sheet having a void-type receiving layer will be described. Recording papers having a void-type receiving layer generally have an ink image-receiving layer provided on a paper support, and the ink-receiving layer contains fine particles and a hydrophilic binder. Examples of the fine particles used include organic fine particles and inorganic fine particles. In particular, inorganic fine particles are preferably used, and examples thereof include light calcium carbonate, heavy calcium carbonate, magnesium carbonate,
Kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc hydroxide, zinc sulfide, zinc carbonate, hydrotalcite, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate,
Synthetic amorphous silica, colloidal silica, alumina, colloidal alumina, pseudoboehmite, aluminum hydroxide,
Examples thereof include white inorganic pigments such as lithopone, zeolite, and magnesium hydroxide. As the inorganic fine particles, both those having an anionic surface and those having a cationic surface can be used.

Examples of the hydrophilic binder used in the ink receiving layer include polyvinyl alcohol, gelatin, polyethylene oxide, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyurethane, dextran, dextrin, color ginnan (λ, ι, etc.),
Agar, pullulan, water-soluble polyvinyl butyral, hydroxyethyl cellulose, carboxymethyl cellulose and the like can be mentioned. Two or more of these hydrophilic binders can be used in combination. A preferably used hydrophilic binder is polyvinyl alcohol. These polyvinyl alcohols include not only ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate, but also modified polyvinyl alcohol such as polyvinyl alcohol having a cation-modified terminal or anion-modified polyvinyl alcohol having an anionic group. . The ratio of the inorganic fine particles to the hydrophilic binder used in the ink receiving layer is generally from 2: 1 to 10: 1 by mass, and especially from 3: 1 to 8: 1.
Is preferred.

By setting the ratio of the inorganic fine particles to the hydrophilic binder to a high value as described above, the ink receiving layer can achieve a high porosity. The preferred porosity is 40
To 80%, and particularly preferably 50 to 70%. Here, the porosity is obtained according to the following equation. Porosity = 100 × (total dry film thickness−coated solid film thickness) / total dry film thickness

[0028]

EXAMPLES A yellow dispersion 1, a magenta dispersion 1, a cyan dispersion 1 and a black dispersion 1 were prepared as follows. (Adjustment of Yellow Dispersion 1) C.I. I. 100 g of CI Pigment Yellow 128 • 100 g of styrene-acrylic acid-methyl methacrylate copolymer (molecular weight 10,000, acid value 160) • 80 g of glycerin • 220 g of ion-exchanged water are mixed with 0.3 mm zirconia beads at a volume ratio of 6 g.
A 0% -filled horizontal bead mill (Ashizawa Co., Ltd., System Zeta Mini) was used to disperse the yellow pigment dispersion 1
I got The average particle size of the pigment particles in the obtained yellow pigment dispersion 1 was 128 nm. Zetasizer 1000 (manufactured by Malvern) was used for measuring the average particle size (the same applies hereinafter).

(Preparation of magenta dispersion 1) I. Pigment Red 122 100 g ・ Joncryl 61 (acrylic-styrene resin, manufactured by Johnson) 100 g ・ Ion-exchanged water 300 g is mixed, and 0.3 mm zirconia beads are mixed at a volume ratio of 6
A 0% -filled horizontal bead mill (Ashizawa Co., Ltd., System Zeta Mini) was used to disperse the magenta pigment dispersion 1
I got The average particle size of the pigment particles in the obtained magenta pigment dispersion 1 was 105 nm.

(Preparation of Cyan Dispersion 1) I. Pigment Blue 15: 3 100 g ・ Demol C (manufactured by Kao Corporation) 60 g ・ Glycerin 40 g ・ Ion-exchanged water 300 g are mixed, and 0.3 mm zirconia beads are mixed at a volume ratio of 6%.
The mixture was dispersed using a horizontal bead mill (System Zeta Mini manufactured by Ashizawa Corporation) filled with 0% to obtain a cyan pigment dispersion 1. The average particle size of the pigment particles in the obtained cyan pigment dispersion 1 was 95 nm.

(Preparation of Black Dispersion 1) ・ 150 g of carbon black ・ 80 g of Vanilex RN (manufactured by Nippon Paper Industries) ・ 270 g of ion-exchanged water were mixed, and 0.3 mm zirconia beads were mixed in a volume ratio of 6 g.
A 0% -filled horizontal bead mill (Ashizawa Co., Ltd., System Zeta Mini) was used to disperse the black pigment dispersion 1
I got The average particle size of the pigment particles in the obtained black pigment dispersion 1 was 83 nm.

Using the obtained yellow dispersion 1, magenta dispersion 1, cyan dispersion 1 and black dispersion 1, the following yellow ink, magenta ink, cyan ink,
Adjusted black ink. (Yellow Ink 1) Yellow dispersion 1 15 g Water-soluble photocurable monomer / oligomer (UA-R1) (urethane acrylate, manufactured by Kyoeisha Chemical Co., Ltd.) 5 g Ethylene glycol 20 g Diethylene glycol 10 g Ion-exchanged water 50 g or more Mix and stir the composition, filter through a 1 μm filter,
Yellow ink 1 (the present invention) was produced.

(Yellow Ink 2) Yellow dispersion 1 15 g Water-soluble photocurable monomer / oligomer (Aronix TO-1321) (polyester acrylate, manufactured by Toagosei Co., Ltd.) 3 g Ethylene glycol 15 g Diethylene glycol monomethyl ether 10 g -0.2 g of Emulgen 120 (manufactured by Kao Corporation)-56.8 g of ion-exchanged water A mixture of not less than 56.8 g was mixed and stirred, and filtered with a 1 µm filter.
Yellow ink 2 (the present invention) was produced.

(Comparative Yellow Ink) A comparative yellow ink was prepared in the same manner as the yellow ink 1 except that the water-soluble photocurable monomer / oligomer (UA-R1) was omitted. Produced.

(Magenta Ink 1) Magenta Dispersion 1 15 g Water-soluble photocurable monomer / oligomer (UA-7200) (urethane acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.) 1 g Ethylene glycol 25 g Diethylene glycol monobutyl ether 5 g 0.2 g of Surfynol 465 (manufactured by Nissin Chemical Co., Ltd.) 53.8 g of ion-exchanged water The above composition was mixed and stirred, and filtered with a 1 μm filter.
Magenta ink 1 (the present invention) was produced.

(Magenta Ink 2) Magenta Dispersion 1 15 g Water-soluble photocurable monomer / oligomer (WS-12) (urethane acrylate, manufactured by Kyoeisha Chemical Co., Ltd.) 10 g Levenol WX (Kao Corporation) 0.2 g 2 g of Takelac W605 (manufactured by Takeda Pharmaceutical Co., Ltd.)-72.8 g of ion-exchanged water The above composition was mixed and stirred, and filtered with a 1 µm filter.
Magenta ink 2 (the present invention) was produced.

(Comparative magenta ink) Instead of the water-soluble photocurable monomer / oligomer (UA-7200), a water-soluble photocurable monomer / oligomer (A-400) (polyethylene glycol acrylate, manufactured by Shin-Nakamura Chemical Co., Ltd.)
Comparative magenta ink was prepared in the same manner as magenta ink 1 except that was used.

(Cyan ink 1) Cyan dispersion 1 10 g Water-soluble photocurable monomer / oligomer (UA-W2A) (urethane acrylate, Shin-Nakamura Chemical Co., Ltd.) 3 g Diethylene glycol 15 g Triethylene glycol 20 g Perex OP -T (manufactured by Kao Corporation) 0.2 g ・ S-120 polyolefin iomer (manufactured by Mitsui Chemicals, Inc.) 2 g or more of the composition was mixed and stirred, and filtered with a 1 μm filter.
Cyan ink 1 (the present invention) was produced.

(Cyan Ink 2) Cyan Dispersion 1 10 g Water-soluble photocurable monomer / oligomer (GX-8507C) (urethane acrylate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1 g Ethylene glycol 30 g Pluronic L -44 (manufactured by Asahi Denka Co., Ltd.) 1 g ・ Ion-exchanged water 58 g
Cyan ink 2 (the present invention) was produced.

(Comparative cyan ink) Water-dispersible photocurable monomer / oligomer (KOW-3E) (polyethylene glycol acrylate, manufactured by Nippon Kayaku Co., Ltd.) instead of water-soluble photocurable monomer / oligomer (UA-W2A) Comparative Cyan Ink was prepared in the same manner as Cyan Ink 1 except that was used.

(Black ink 1) 15 g of black dispersion 1 3 g of water-soluble photo-curable monomer / oligomer (UA-7200) (urethane acrylate bifunctional, manufactured by Shin-Nakamura Chemical Co., Ltd.) 3 g of ethylene glycol 30 g Nipol SX1503 (Manufactured by ZEON CORPORATION) 0.5 g ・ Ion-exchanged water 51.5 g The above composition was mixed and stirred, and filtered with a 1 μm filter.
Black ink 1 (the present invention) was produced.

(Black Ink 2) 15 g of black dispersion 1 5 g of water-soluble photocurable monomer / oligomer (UA-W2A) 20 g of ethylene glycol 5 g of triethylene glycol monoethyl ether 45 g of ion-exchanged water Stir and filter through a 1 μm filter,
Black ink 2 (the present invention) was produced.

Comparative Black Ink Same as Black Ink 1 except that a water-soluble monofunctional photocurable monomer (2-hydroxyethyl acrylate) was used instead of the water-soluble photocurable monomer / oligomer (UA-7200) Thus, a comparative black ink was prepared.

<< Evaluation of Glossiness >><Preparation of Evaluation Sample> A piezo-type head having a nozzle hole diameter of 20 μm, a driving frequency of 12 kHz, a number of nozzles of 128 per color, and a nozzle density of 180 dpi between the same colors is mounted. Using a 720 × 720 dpi on-demand ink jet printer, Konica Photojet QP paper thick [gap type image receiving layer type] (a) and Kodak ink jet dedicated glossy paper thick [swelling type image receiving layer type] ( b) A uniform image pattern giving a reflection density of 1.5 was recorded thereon. <Evaluation> The evaluation sample image was converted to an image clarity measuring device ICM-1D.
Reflection at P (manufactured by Suga Test Machine Co.) 60 degrees, optical comb 2 mm
(C value%) was measured, and the glossiness was evaluated according to the following evaluation criteria. (Evaluation criteria) ○: C value% is 50% or more △: C value% is 40% or more and less than 50% ×: C value% is less than 40%

<< Evaluation of Storage Stability >> Each ink was put in a 10 ml glass sample tube and stored at 50 ° C. for 3 months. Thereafter, the concentration of the supernatant liquid of the ink was measured, compared with the initial value, the residual ratio of the pigment was determined by the following formula, and the storage stability was evaluated by the following criteria. (Pigment residual ratio%) = (Pigment concentration after storage) / (Pigment concentration before storage) × 100 (Evaluation criteria) ○: Pigment residual ratio% is 90% or more △: Pigment residual ratio% is 70% or more, 90 %: Pigment residual rate% is less than 70%

<< Evaluation of Ejection Stability >> Using each ink, the ink-jet printer used in the preparation of the above-mentioned evaluation sample was a cycle of 8 hours continuous printing and a subsequent 14 hour pause, and this cycle was 3 cycles. After repeating the cycle, the number of non-discharge nozzles was confirmed, and discharge stability was evaluated according to the following criteria. (Evaluation criteria) ；: Number of non-discharge nozzles is 0 Δ; Number of non-discharge nozzles is 1 to 3 ×; Number of non-discharge nozzles is 4 or more. The results are also shown in Table 1.

[0047]

[Table 1]

[0048]

The aqueous pigment ink for ink-jet recording of the present invention has excellent storage stability and ejection stability, and can provide a high gloss image on a glossy medium for ink-jet recording. According to the recording method, an image having high glossiness can be obtained on the glossy medium for inkjet.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C056 EA04 FC01 FC02 FC06 2H086 BA15 BA53 BA55 BA59 4J039 AD21 BD02 BE01 CA03 EA05 EA33 EA44 EA46 GA24

Claims (4)

[Claims] 1. An aqueous pigment ink containing a water-soluble photocurable monomer and / or oligomer containing two or more functional groups in an aqueous medium and a pigment, wherein a water-soluble photocurable monomer containing two or more functional groups is provided. An aqueous pigment ink for inkjet, wherein the oligomer is a compound having a group represented by the following formula. -(X) m- (C = O) -Y- (Formula) (wherein, X and Y represent an oxygen atom or a nitrogen atom;
Represents 0 or 1. ) 2. A water-soluble photocurable monomer or oligomer,
The aqueous pigment ink for inkjet according to claim 1, wherein the pigment is a water-soluble photocurable monomer or oligomer having a urethane group or an ester group in the molecule. 3. A water-soluble photocurable monomer or oligomer,
The water-based pigment ink for inkjet according to claim 1, which is a water-soluble photocurable monomer or oligomer having a weight average molecular weight of 1,000 or more and 50,000 or less. 4. An ink jet recording method comprising discharging the aqueous pigment ink for ink jet according to claim 1 onto a recording medium having a void type image receiving layer to form an image.