JP2021031616A - Aqueous pigment dispersion, inkjet printing ink, and printed matter - Google Patents

Abstract

To provide an aqueous pigment dispersion which, in an inkjet printing ink, can satisfy both glossiness and light fastness, and to provide an inkjet printing ink using the aqueous pigment dispersion and printed matter using the inkjet printing ink.SOLUTION: Provided is an aqueous pigment dispersion comprising a pigment, water, and resin particles. In particle size distribution of the resin particles, an abundance ratio of a particle size of 20 to 60 nm as fraction 1 is 50 to 80%, an abundance ratio of a particle size of 100 to 300 nm as fraction 2 is 10 to 30%, and a total of abundance ratios of fraction 1 and fraction 2 relative to the whole particle size distribution is 70% or more.SELECTED DRAWING: None

Description

The present invention relates to an aqueous pigment dispersion capable of providing an ink for inkjet recording having excellent gloss and light resistance. The present invention also relates to an inkjet recording ink containing the aqueous pigment dispersion and a printed matter using the inkjet recording ink.

With the spread of inkjet printers in recent years, the quality of the inkjet recording ink used for these printers is required to be further improved. For example, the required quality of a photo inkjet printer or a large format inkjet printer requires excellent image characteristics in addition to productivity, so-called output speed.
In particular, in yellow pigments, there is a trade-off relationship between glossiness and light resistance, and the current situation is that there is no molecular structure that achieves both of these.

Under these circumstances, attempts have been made to control the particle size and use additives, etc., rather than seeking a solution for the pigment structure to be used. However, although all of them have a certain effect, they have not yet satisfied the demand for high quality in recent years. In addition, if a large amount of additive is added, there is a high possibility that the ejection performance and the image performance will be adversely affected, which is not a preferable method.
Under these circumstances, an inkjet ink containing water, a water-soluble organic solvent, a pigment, polycarbonate-modified polyurethane resin particles, an ultraviolet absorber, and a light stabilizer has been proposed for the purpose of improving light resistance and the like (Patent Documents). 1). However, in the method described in Patent Document 1, since the ultraviolet absorber is not distributed on the surface layer of the dots, the actual situation is that the level of light resistance that has been increasing in recent years has not been satisfied. Further, since the ultraviolet absorber and the light stabilizer may adversely affect the ejection property of the ink, there is a problem that the stability of the dispersion needs to be controlled very high.

Japanese Unexamined Patent Publication No. 2016-006150

An object of the present invention is to provide an aqueous pigment dispersion capable of achieving both glossiness and light resistance in an ink for inkjet printing. Further, the present invention provides an ink for inkjet printing using the aqueous pigment dispersion and a printed matter using the ink for inkjet printing.

As a result of diligent studies, the present inventors have found that an aqueous pigment dispersion containing a pigment, water, and specific resin particles can solve the above-mentioned problems.

That is, the present invention is an aqueous pigment dispersion containing a pigment, water, and resin particles, and in the particle size distribution of the resin particles,
Category 1 has a particle size of 20 to 60 nm and an abundance ratio of 50 to 80%.
Category 2 has a particle size of 100 to 300 nm and an abundance ratio of 10 to 30%.
The present invention provides an aqueous pigment dispersion characterized in that the total abundance ratio of Category 1 and Category 2 is 70% or more with respect to the entire particle size distribution.

Further, the resin particles provide an aqueous pigment dispersion which is a resin emulsion.

Further, the resin particles contain resin particles A and resin particles B, and the average particle size of the resin particles A is 10 to 50 nm, and the average particle size of the resin particles B is 70 to 130 nm. It provides a dispersion.

Further, the present invention provides an ink for inkjet recording characterized by containing the aqueous pigment dispersion, and a printed matter printed with the ink for inkjet recording.

The aqueous pigment dispersion of the present invention can impart high glossiness and high light resistance to the ink for inkjet printing using the dispersion. The printed matter obtained by printing the ink for inkjet printing is excellent in image characteristics, and therefore can be particularly preferably used for a photo or a large format.

The present invention is an aqueous pigment dispersion containing a pigment, water, and resin particles, and in the particle size distribution of the resin particles,
Category 1 has a particle size of 20 to 60 nm and an abundance ratio of 50 to 80%.
Category 2 has a particle size of 100 to 300 nm and an abundance ratio of 10 to 30%.
The present invention provides an aqueous pigment dispersion characterized in that the total abundance ratio of Category 1 and Category 2 is 70% or more with respect to the entire particle size distribution.

The aqueous pigment dispersion of the present invention can exhibit light resistance without using an ultraviolet absorber or a light stabilizer. Further, normally, when resin particles are blended with a pigment dispersion, the glossiness is adversely affected, but the aqueous pigment dispersion of the present invention has no adverse effect on the glossiness and can be compatible with light resistance.

<Resin particles>
The aqueous pigment dispersion of the present invention contains resin particles. The resin particles of the present invention are resins that have dispersibility in an aqueous medium and exist in the form of particles in a dispersion. The resin particles may be solid particles, but are preferably present in the dispersion as a resin emulsion.

The resin particles of the present invention are characterized by having a specific particle size distribution. Specifically, in the particle size distribution of the entire resin particles, the abundance ratio of the particle diameter of 20 to 60 nm is 50 to 80% as the category 1, and the abundance ratio of the particle diameter of 100 to 300 nm is 10 to 30% as the category 2. , The total abundance ratio of Category 1 and Category 2 is 70% or more of the entire particle size distribution.

As Category 1, when the abundance ratio of the particle diameter of 20 to 60 nm is 50 to 80%, the glossiness is excellent. Preferably, it is 55-65%.
Further, as Category 2, when the abundance ratio of the particle diameter of 100 to 300 nm is 10 to 30%, the light resistance is excellent. It is preferably 15 to 25%.
When the total abundance ratio of Category 1 and Category 2 is 70% or more with respect to the entire particle size distribution, both glossiness and light resistance can be achieved at the same time. It is preferably 75% or more.

In the aqueous pigment dispersion of the present invention, the blending amount of the resin particles is preferably in the range of 5 to 80 parts by mass with respect to 100 parts by mass of the pigment. From the viewpoint of storage stability and ejection property after inking, the amount is more preferably 10 to 50 parts by mass with respect to 100 parts by mass of the pigment. More preferably, it is 10 to 30 parts by mass.

As described above, the resin particles of the present invention have the particle size distribution of the resin particles.
Category 1 has a particle size of 20 to 60 nm and an abundance ratio of 50 to 80%.
Category 2 has a particle size of 100 to 300 nm and an abundance ratio of 10 to 30%.
The total abundance ratio of Category 1 and Category 2 is 70% or more of the entire particle size distribution. The method for preparing the particle size distribution of the resin particles is not particularly limited, but a method in which a resin particle having a small particle size and a resin particle having a large particle size are mixed and used is convenient.

The resin of the resin particles is not particularly limited, but is preferably at least one of a polyurethane resin, a polyolefin resin, and a poly (meth) acrylic resin. These resins may be used alone or in combination.

Examples of the polyurethane resin include a polyether polyurethane resin, a polyester polyurethane resin, and a polycarbonate polyurethane resin. Among these, polycarbonate-based polyurethane resin is preferable from the viewpoint of light resistance. The polycarbonate-based polyurethane is obtained by reacting a polycarbonate compound having an active hydrogen, a compound having at least one active hydrogen group and a hydrophilic group, and a compound having an isocyanate group.

The polyolefin resin is a polymer or copolymer containing an olefin-based monomer as a main component. Examples of the olefin-based monomer include α-olefins such as propylene, butene, hexene, methylbutene, methylpentene and methylhexene, and cyclic olefins such as norbornene, in addition to ethylene. Among these, it is preferable to use ethylene or propylene as a main component from the viewpoint of gloss.

The poly (meth) acrylic resin refers to a resin having at least a known (meth) acrylic acid ester monomer as a constituent unit, and is an acrylic resin, a styrene-acrylic resin, a polyester-acrylic resin, a urethane-acrylic resin, or the like. Vinyl chloride Vinyl acetate copolymer-acrylic resin, silicone-acrylic resin, acrylamide resin, epoxy-acrylic resin and the like can be mentioned. Among these, acrylic resin and styrene-acrylic resin are preferable from the viewpoint of achieving both light resistance and gloss.

In the present invention, the particle size distribution of the resin particles is measured by "Nanotrac UPA-EX150" manufactured by Microtrac Bell Co., Ltd. The measurement sample is used by diluting a single emulsion or an emulsion mixed at a predetermined ratio with ion-exchanged water. In the present invention, the abundance ratio of a particle size of 20 to 60 nm refers to the cumulative frequency of 0.0215 to 0.00608 um in the measurement results. The abundance ratio of a particle size of 100 to 300 nm refers to a cumulative frequency of 0.102 to 0.289 um. Further, the average particle size refers to the volume average particle size.

As for the resin particles, in the particle size distribution of the entire resin particles, the abundance ratio of the particle diameter of 20 to 60 nm is 50 to 80% as the category 1, and the abundance ratio of the particle diameter of 100 to 300 nm is 10 to 30% as the category 2. The total abundance ratio of Category 1 and Category 2 is 70% or more of the entire particle size distribution. At this time, there are resin particles A having an average particle size of 10 to 50 nm, and the average particle size is 70 to 130 nm. It is preferable that the resin particles B are composed of the above.

The resin particles A and the resin particles B may be made of the same material or different materials.
The resin particles A and the resin particles B are preferably at least one of a polyurethane resin, a polyolefin resin, and a poly (meth) acrylic resin, respectively.

As the resin particles A, a poly (meth) acrylic resin or a polyolefin resin is more preferable because it has excellent glossiness.

As the resin particles B, poly (meth) acrylic resin and polyurethane resin are more preferable because they are particularly excellent in light resistance.
The resin particles B preferably have an acid value. When the acid value is 5 mg / KOHg or more, the dispersion stability of the resin particles is further improved. Further, when it is 60 mg / KOHg or less, when printing an inkjet recording ink containing resin particles, the resin particles easily stay on the surface after penetrating into the object to be recorded, so that the light resistance is excellent. Particularly preferably, it is 5 to 30 mg / KOHg.

The resin particles preferably contain the above-mentioned resin particles A and resin particles B, but it is preferable to mix the resin particles A and the resin particles B in a mass ratio of 2: 8 to 8: 2 in order to prepare the particle size distribution. .. It is more preferably 3: 7 to 7: 3, and even more preferably 4: 6 to 6: 4.

The resin particles may be adjusted by blending the resin with water or a pigment and then emulsifying the resin into particles by sharing the share, or the resin already in the form of particles may be blended with water or a pigment. A method of producing an aqueous pigment dispersion by blending an emulsified resin dispersion with water or a pigment is preferable because it is simple and stable.

<Pigment>
The pigment used for preparing the aqueous pigment dispersion of the present invention is an organic pigment or an inorganic pigment, and any known and commonly used pigment can be used. For example, azo, disazo, azomethin, anthraquinone, quinophthalone, quinacridone, diketopyrrolopyrrole, dioxazine, benzimidazolone, phthalocyanine, isoindoline, isoindolinone, perylene, etc. Organic pigments, inorganic pigments such as carbon black can be mentioned.
The pigment may be used alone or in combination of two or more.

The hue of the above pigment is not particularly limited, but the present invention is characterized in that even an aqueous pigment dispersion using a yellow pigment, which has problems in color development and light resistance, has high effects of color development and light resistance. Is listed as.
Examples of the yellow pigment include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 120, 128, 129, 147, 213, 214, 150, 151, 155, 180, 185 and the like can be used alone or in combination of two or more, among which C.I. I. Pigment Yellow 74 can be used particularly favorably.

<Dispersion medium>
The aqueous pigment dispersion of the present invention contains a dispersion medium in addition to the pigment and resin particles. Examples of the dispersion medium include water, a water-soluble organic solvent, and the like.

As the water, pure water such as ion-exchanged water, ultra-filtered water, reverse osmosis water, distilled water, or ultrapure water can be used. Further, as the water, water sterilized by ultraviolet irradiation or addition of hydrogen peroxide can be used to prevent the growth of mold or bacteria when the aqueous pigment dispersion or the ink using the aqueous pigment dispersion is stored for a long period of time. It is suitable because it can be used.

Examples of the water-soluble organic solvent include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and butyl. Alcohols such as alcohols, pentyl alcohols, and similar alcohols; ethers such as tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, etc .; amides such as dimethylformamide, N-methylpyrrolidone, etc. Be done.

In addition, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol and polypropylene glycol; diols such as butanediol, pentanediol, hexanediol and diols of the same family; lauric acid. Glycol esters such as propylene glycol; glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl ethers, propylene glycol ethers, dipropylene glycol ethers, and cellosolves containing triethylene glycol ethers; or sulfolanes; Diols such as γ-butyrolactone; lactams such as 2-pyrrolidone and N- (2-hydroxyethyl) pyrrolidone; glycerin and its derivatives, polyoxyethylene benzyl alcohol ether and the like can also be used.
These water-soluble organic solvents can be used alone or in admixture of two or more.

In the aqueous pigment dispersion of the present invention, the blending amount of the dispersion medium may be appropriately adjusted depending on the intended use, but it is preferable to blend 60 to 95 parts by mass with respect to the total amount of the non-volatile content of the aqueous pigment dispersion for dispersion stability. It is preferable from the point of view.

<Aqueous polyurethane resin>
The aqueous pigment dispersion of the present invention preferably contains an aqueous polyurethane resin in addition to the above components. By containing the aqueous polyurethane resin, the dispersibility and dispersion stability of the pigment are improved. Further, by containing the water-based polyurethane resin, the ejection property after inking is stabilized. The water-based polyurethane resin means a polyurethane resin that is highly hydrophilic and can exist in the water-based medium in a state where it is not dissolved in the water-based medium to form particles having a particle size.
Examples of the aqueous polyurethane resin include polyether polyurethane.

The aqueous polyurethane resin is preferably blended in an amount of 5 to 60 parts by mass with respect to 100 parts by mass of the pigment because the dispersion stability of the pigment is improved. Particularly preferably, it is 10 to 40 parts by mass.

<Other formulations>
The aqueous pigment dispersion of the present invention may contain a compound other than the above components. The aqueous pigment dispersion of the present invention has excellent light resistance as it is, but does not prevent the use of an ultraviolet absorber, an ultraviolet reflector, a light stabilizer, or the like.
Further, as other formulations, a fungicide, a bactericidal agent, an antibacterial agent, a wetting agent, a surfactant, a chelating agent, an antioxidant, a pH adjusting agent and the like may be blended.

<Ink for inkjet recording>
An ink for inkjet recording can be obtained by further diluting the aqueous pigment dispersion of the present invention with a dispersion medium. The ink for inkjet recording of the present invention can achieve both high gloss and light resistance due to the effect of the aqueous pigment dispersion of the present invention.

When the ink for inkjet recording is used, it is preferable to dilute it so that the pigment content is 1 to 8% by mass, but the ink is not limited to this range and may be appropriately adjusted depending on the application and the ejection method. Ink for inkjet recording includes not only the above-mentioned dispersion medium, but also an ultraviolet absorber, an ultraviolet reflector, a light stabilizer, a fungicide, a bactericidal agent, an antibacterial agent, a wetting agent, a surfactant, a chelating agent, and an oxidation. Compounds such as an inhibitor and a pH adjuster may be added.

Further, the ink for inkjet recording can be made into an ink with less clogging at the time of ejection by performing filter filtration as necessary.
The ejection method at the time of inkjet printing is not particularly limited, and any method such as a piezo method or a thermal method can be used.

<Printed matter>
The printed matter printed by the inkjet recording ink of the present invention has excellent image characteristics because it has high gloss and high light resistance. In particular, it is suitable as a printed matter for photographs and large formats that require high image characteristics.
The recording medium for printing is not particularly limited, and can be used for paper, plastic, wood, woven fabrics and non-woven fabrics, metals and metal oxides, glass, ceramics, various building materials such as plaster and mortar, and the like.

Hereinafter, the present invention will be described in detail with reference to Examples, but these Examples specifically describe the present invention, and the embodiment is not limited thereto. In the examples, unless otherwise specified, it is converted to mass.

<Measurement of particle size>
The particle size of the resin particles was measured by the following method.
Resin particles diluted with ion-exchanged water were packed in a cell and measured using UPA-EX150 under the following conditions.
・ Loading index: 5 ± 1
-Measurement time: 180 seconds-Number of measurements: 5 times-Transparency: Transmission-Particle refractive index: 1.80
・ Shape: True sphere ・ Density: 1.00
-Solvent refractive index: 1.333
・ Viscosity at high temperature: 30 ℃, 0.797
-Viscosity at low temperature: 20 ° C, 1.002
-Filter: Stand: Norm
-Sensitivity: Standard
・ UPA compatibility mode

Synthesis Example 1 <Synthesis of poly (meth) acrylic acid ester resin 1>
Isopropyl in the reaction vessel of an automatic polymerization reactor (polymerization tester DSL-2AS type, manufactured by Todoroki Sangyo Co., Ltd.) having a reaction vessel equipped with a stirrer, a dropping device, a temperature sensor, and a reflux device having a nitrogen introduction device at the top. 1,200 parts of alcohol was charged, and the inside of the reaction vessel was replaced with nitrogen while stirring. After raising the temperature in the reaction vessel to 80 ° C. while maintaining a nitrogen atmosphere, 75.0 parts of 2-hydroxyethyl methacrylate, 260.8 parts of methacrylic acid, 400.0 parts of styrene, and benzyl methacrylate 234. A mixture of 2 parts, 30.0 parts of glycidyl methacrylate, and 80.0 parts of "Perbutyl O (registered trademark)" (active ingredient t-butyl peroxy2-ethylhexanoate, manufactured by Nippon Oil & Fats Co., Ltd.) for 4 hours. Dropped over. After completion of the dropping, the reaction was continued at the same temperature for 15 hours, and then the non-volatile content was adjusted to 50% to obtain a (meth) acrylic acid ester resin solution 1 having an acid value of 170.

Synthesis Example 2 <Synthesis of Resin Particle 1>
Polycarbonate diol 1 (weight average molecular weight: 2) based on 1,6-hexanediol / 1,4-butanediol in a four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube under a nitrogen stream. 000) 964 parts, 43 parts of dimethylol propionic acid and 558 parts of methyl ethyl ketone were added and mixed uniformly. Next, after adding 295 parts of dicyclohexylmethane diisocyanate, 0.05 part of tin dioctylate was added, and the mixture was reacted at 70 ° C. for about 4 hours to prepare a methyl ethyl ketone solution of a urethane prepolymer having an acid value of 14 having an isocyanate group at the molecular terminal. Got Further, 33 parts of triethylamine was added to neutralize the carboxyl group in the urethane prepolymer, and then 2,516 parts of ion-exchanged water was gradually added. Then, 19 parts of ethylenediamine was added and reacted. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure to obtain resin particles 1 having a non-volatile content of 35% and an average particle size of 119 nm.

Synthesis Example 3 <Synthesis of Aqueous Polyurethane Resin 1>
A four-necked flask equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen blowing tube is charged with 480 parts of polypropylene glycol having a weight average molecular weight of 2,000, 263 parts of isophorone diisocyanate, and 0.007 parts of dibutyltin dilaurate. , The reaction was carried out at 100 ° C. for 1 hour in a nitrogen gas atmosphere. After that, the mixture was cooled to 65 ° C. or lower, 115 parts of dimethylol propionic acid, 14 parts of neopentyl glycol, and 291 parts of methyl ethyl ketone were added and reacted at 75 ° C. for 6 hours to bring the polystyrene-equivalent weight average molecular weight by GPC to 15,400. After confirming that, 140 parts of methyl ethyl ketone and methanol were added to terminate the reaction to obtain a linear acid group-containing polyether polyurethane resin having an acid value of 52. Further, 95 parts of 48% potassium hydroxide was added, and the mixture was stirred for 1 hour. Then, 4107 parts of ion-exchanged water was added, and distillation was carried out under reduced pressure at 40 ° C. Methyl ethyl ketone was completely distilled off to obtain an aqueous polyurethane resin 1.

Production Example 1 <Production of Mill Dispersion Solution 1>
In a mixing tank equipped with a cooling jacket, C.I. I. Pigment Yellow 74 (manufactured by Sanyo Dye Co., Ltd.) 500 parts, 150 parts of the poly (meth) acrylic acid ester resin 1 obtained in Synthesis Example 1, 51 parts of a 25% sodium hydroxide aqueous solution, 175 parts of isopropyl alcohol, 1107 parts of ion-exchanged water was charged and mixed with an emulsifying device (IKA registered trademark LABOR-PILOT DR2000 / 4 IKA-WERK GMBH & CO. KG) for 1 hour. 129 parts of ion-exchanged water was added to the obtained mixed solution, and the mixture was passed through a disperser (SC mill SC100 / 32 type, manufactured by Nippon Coke Industries Co., Ltd.) filled with zirconia beads having a diameter of 0.3 mm, and circulated (dispersed). The dispersion was dispersed by returning the dispersion liquid from the apparatus to the mixing tank). During the dispersion step, cold water was passed through a cooling jacket to control the dispersion temperature to be kept at 30 ° C. or lower, and the rotor peripheral speed of the dispersion device was fixed at 11.25 m / sec to disperse for 5 hours. After completion of the dispersion, the dispersion stock solution was withdrawn from the mixing tank, and then the mixing tank and the flow path of the dispersion device were washed with 1400 parts of water and combined with the dispersion stock solution. The dispersion was placed in a glass distillation apparatus, and the entire amount of isopropyl alcohol and a part of water were distilled off. After allowing to cool to room temperature, 2% hydrochloric acid was added dropwise with stirring to adjust the pH to 4, and then the solid content was filtered with a Nutche-type filtration device and washed with water. Take 800 parts of cake (non-volatile content 30% by mass) into a container, add 15.3 parts of 25% sodium hydroxide aqueous solution, and then re-use with Disper (TK Homo Disper 20 type, manufactured by Tokushu Kika Kogyo Co., Ltd.). Distributed. Further, water was added to adjust the non-volatile content to 23% by weight, and then centrifugation was performed at 6,000 G for 30 minutes. After centrifugation, ion-exchanged water was added to the slurry to produce a mill dispersion liquid 1 having a pigment content of 18% in terms of mass.

(Example 1)
<Manufacturing of Pigment Dispersion 1>
72 parts of mill dispersion, 3.3 parts of Hiros-XX-436 (manufactured by Starlight PMC Co., Ltd., average particle size 25 nm, acid value: 33) and M141 (manufactured by Starlight PMC Co., Ltd., average grain) as resin particles Diameter 71 nm, acid value: 19) 2.8 parts, Proxel GXL (S) (Lonza Japan Co., Ltd.) 0.2 parts as an antiseptic, ion-exchanged water to make a total of 100 parts, paint shaker ( Toyo Seiki Seisakusho Co., Ltd. (with an amplitude of 750 / min) was stirred for 30 minutes to obtain a pigment dispersion 1 having a pigment content of 13% and a resin particle content of 2.6% in terms of mass.

(Examples 2 to 5, Comparative Examples 1 to 4)
Pigment dispersions 2 to 5 and comparative dispersions 1 to 4 were obtained in the same manner except that the formulation of Example 1 was changed to Tables 1 and 2 below.

The materials used in the table are as follows.
Resin particles 2 JONCRYL PDX-7787 (manufactured by BASF Japan Ltd., average particle size 82 nm, acid value 100)
Resin particles 3 Arrow base DB-4010 (manufactured by Unitika Ltd., average particle size 31 nm, acid value 35)

(Example 6)
<Manufacturing of Ink Composition 1>
The obtained pigment dispersion 1 was blended as shown in Table 3 below and stirred with a paint shaker for 30 minutes to produce an ink composition 1.

(Examples 7 to 10, Comparative Examples 5 to 8)
<Ink Compositions 2-5, Comparative Inks 1-4>
Ink compositions 2 to 5 and comparative inks 1 to 4 were obtained in the same manner except that the composition of the ink composition 1 was changed to Tables 3 and 4 below.

The materials used in the table are as follows.
Surfinol 465: Surfactant; manufactured by Air Products & Chemicals, Inc.

The evaluation method is as follows.
<Light resistance test>
The ink was filled in a cartridge of a commercially available inkjet printer (PX-045A, manufactured by Seiko Epson Corporation). Then, printing was performed on photo paper (GL-101 A450, manufactured by Canon Inc.) so that the optical density (hereinafter referred to as OD) was 0.5 ± 0.05. Here, OD was measured using SpectroEye (manufactured by X-Rite Co., Ltd.) with the density filter set to yellow.
The obtained printed matter was measured with an eye super xenon tester XER-W83 (xenon arc lamp type / manufactured by Iwasaki Electric Co., Ltd.) by a method conforming to the JEITA CP3901 standard (indoor light resistance test).
・ Radiant intensity: 47W / m2 @ 300-400nm
・ Temperature: 50 ℃
・ Humidity: 70% (no watering)
・ Irradiation time: 200 hours ・ OD of test piece: 0.5 ± 0.05
-Light resistance: (OD after test) / (OD before test) x 100 (%)

<Gloss test>
The ink was filled in a cartridge of a commercially available inkjet printer (PX-045A, manufactured by Seiko Epson Corporation). After that, printing was performed on photo paper (GL-101 A450, manufactured by Canon Inc.) so that the duty was 100%. The obtained printed matter was color-measured with a haze-gloss Reflectometer (manufactured by BYK-Gardner USA), and the obtained 20 ° gloss was defined as "gloss".

The aqueous pigment dispersion of the present invention can impart high glossiness and high light resistance to the ink for inkjet printing using the dispersion. The printed matter obtained by printing the ink for inkjet printing is excellent in image characteristics, and therefore can be particularly preferably used for a photo or a large format.

Claims (7)

An aqueous pigment dispersion containing a pigment, water, and resin particles, and in the particle size distribution of the resin particles,
Category 1 has a particle size of 20 to 60 nm and an abundance ratio of 50 to 80%.
Category 2 has a particle size of 100 to 300 nm and an abundance ratio of 10 to 30%.
An aqueous pigment dispersion, wherein the total abundance ratio of Category 1 and Category 2 is 70% or more with respect to the entire particle size distribution. The aqueous pigment dispersion according to claim 1, wherein the resin particles are a resin emulsion. Claim 1 in which the resin particles contain resin particles A and resin particles B, the average particle size of the resin particles A is 10 to 50 nm, and the average particle size of the resin particles B is 70 to 130 nm. Alternatively, the aqueous pigment dispersion according to 2. The aqueous pigment dispersion according to claim 3, wherein the resin particles B have an acid value of 5 to 60 mg / KOHg. The aqueous pigment dispersion according to any one of claims 1 to 4, wherein the resin particles are at least one selected from a urethane resin, a polyolefin resin, and a (meth) acrylic resin. An ink for inkjet recording, which comprises the aqueous pigment dispersion according to any one of claims 1 to 5. A printed matter printed with the inkjet recording ink according to claim 6.