JP2001348523A - Aqueous pigment dispersion, ink jet recording liquid and method for ink jet recording using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an excellent ink jet recording liquid capable of providing prints excellent in gloss and rub resistance while maintaining a good printing density and good discharge properties of the ink. SOLUTION: This aqueous pigment dispersion is characterized in that carbon black has <=18 nm average primary particle diameter, <=120 cm3/100 g DBP oil absorption volume, <=30 nm aggregate diameter and a value (SD/Dagg) obtained by dividing the standard deviation(SD) of the distribution of the aggregate diameter by the aggregate diameter (Dagg) is <=0.4 in the aqueous pigment dispersion comprising the carbon black and water. The ink jet recording liquid uses the aqueous pigment dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous pigment dispersion, an ink jet recording liquid using the same, and an ink jet recording method for recording the recording liquid on a recording sheet. Excellent in nature,
Further, the present invention relates to an ink jet recording liquid and an ink jet recording method capable of obtaining a printed material excellent in all of print density, print surface gloss, and print surface abrasion resistance.

[0002]

2. Description of the Related Art Conventionally, as a recording liquid for ink jet recording, an aqueous ink in which an acidic dye or a direct dye is dissolved in an aqueous medium, or a solvent-based ink in which an oil-soluble dye is dissolved in an organic solvent has been used. . Since the solvent-based ink uses a solvent, it has a problem in terms of environmental safety, and its use is limited because it is not suitable for use in offices and homes.
On the other hand, general water-based inks use water-soluble dyes (dyes), and have a problem that the water resistance and light resistance of the recorded matter are insufficient. In order to solve this problem, a pigment having excellent water resistance and light resistance is used as a coloring material, and an aqueous pigment-dispersed ink in which the pigment is dispersed in an aqueous medium is partially used. The water-based pigment-dispersed ink for ink-jet recording has an extremely small amount of dispersant resin compared to other pigment inks in order to ensure ejection stability and storage stability. There is a problem that the recording material is damaged due to peeling of the film or soiling of the surroundings, that is, poor so-called scratch resistance. Large format printers for light printing, especially called wide format or large format, are used for printing outdoor posters such as posters. Higher light resistance and water resistance are required as compared to For this reason, in such a printer, a recording method of recording with a water-based pigment-dispersed ink on a recording sheet having an ink receiving layer on the surface of a support such as paper or a resin film is being adopted.
However, when printing on such a recording sheet using a pigment-dispersed ink, particularly a glossy film having a surface gloss, or glossy paper, a recorded matter having excellent print density, light fastness, and water fastness can be obtained, but the pigment which is a pigment Remains on the recording sheet surface and hardly penetrates into the ink receiving layer. Therefore, compared with the case where dye ink penetrating the ink receiving layer is used, there is a problem that the abrasion resistance and gloss of the recording surface are remarkably poor. Was. If a large amount of a water-soluble resin such as a polymer dispersant is added to the ink, the abrasion resistance and gloss can be improved, but the ejection stability, which is an essential condition for ink jet recording ink, is impaired. There is a problem, and an ink satisfying all of the conventional methods has not been obtained.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a recording sheet comprising an ink receiving layer provided on a support, particularly glossy paper,
When recording an aqueous pigment dispersion containing carbon black and water by an inkjet method on a glossy film, while maintaining excellent ejection stability of the ink, not only print density, light resistance, and water resistance, It is an object of the present invention to provide an ink jet recording method which provides a recorded matter having extremely excellent gloss and scratch resistance.

[0004]

As a result of various studies on an ink jet recording liquid containing carbon black as a pigment, the present inventors have found that the primary recording medium has a smaller primary particle diameter, a lower structure, and a smaller aggregate diameter than ordinary carbon black. By using a specific carbon black with a very narrow distribution, there is no need to add excessive resin to the recording liquid, and excellent surface abrasion resistance and gloss are maintained while maintaining excellent ejection stability and recording density. It has been found that the recorded matter obtained is obtained, and the present invention has been achieved.

That is, the gist of the present invention is to provide an ink jet recording liquid containing carbon black and water, wherein the carbon black has an average primary particle diameter of 18 nm or less.
DBP oil absorption of 120 cm ^3/100 g or less, the aggregate diameter of at 30nm or less, and the value of the standard deviation (SD) divided by aggregate size (Dagg) of the aggregate size distribution (SD / Dagg) 0.4 An inkjet recording liquid characterized by the following.

That is, by selecting carbon black as described above, a very dense aggregate structure of carbon black is formed in the dried recording material coating film, and the strength of the coating film is improved and the surface is improved. This is considered to be due to the fact that the abrasion resistance and the luster were dramatically improved due to the smoothness.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The present invention relates to a recording liquid for recording by an ink jet method using an aqueous pigment dispersion containing a specific carbon black and water as a recording liquid. Preferably, by recording such a recording liquid on a recording sheet having an ink receiving layer provided on a support by an ink jet method, it becomes possible to perform recording with more excellent abrasion resistance and gloss. is there.

The method for producing carbon black used in the aqueous pigment dispersion of the present invention is not particularly limited, and known carbon blacks such as acetylene black, channel black and furnace black can be used. Furnace black is preferred, and furnace black is particularly preferred. The carbon black used in the aqueous pigment dispersion of the present invention has an average primary particle diameter of 18 nm or less, and preferably 16 nm or less.
nm or less, more preferably 15 nm or less. Scratch resistance of the recorded matter obtained as the average primary particle diameter is smaller,
Gloss tends to be improved, and if it is out of the above range, the scratch resistance and gloss of the obtained recorded matter deteriorate.

The DBP absorption of carbon black is 120.
cm ^3/100 g using the following ones, but preferably 1
10 cm ^3/100 g or less, more preferably 100 cm ³
/ 100 g or less is desirable. DBP absorption 120cm
If more than ^3/100 g, the abrasion resistance of the recording obtained, gloss is deteriorated. Normally, primary particles of carbon black are fused together to form a grape bunch structure, and the DBP oil absorption is an index of the size of the structure. D defined in the present invention
The BP oil absorption means that the carbon black has a relatively low structure.

Further, it is preferred the nitrogen adsorption specific surface area of the carbon black is 200 meters ² / g or more, more preferably 230 m ² / g or more, more preferably 260 meters ² /
g or more. Nitrogen adsorption specific surface area is 200m ²
If it is less than / g, the scratch resistance and gloss of the obtained recorded matter may be deteriorated. Further, the volatile matter content of the carbon black according to the present invention is usually preferably in the range of 8% by weight or less, and particularly preferably 4% by weight or less. The pH of the recording solution can be 1 to 14, but 3 to 11 is preferable in terms of storage stability of the recording solution, and 6 to 9 is particularly preferable.

The carbon black DBP referred to here
Oil absorption refers to the value measured by JIS K6221A method.
The nitrogen adsorption specific surface area and the volatile content are the values measured by the method of JIS K6221, the average primary particle diameter is the arithmetic average diameter (number average) by an electron microscope, and the pH is the mud obtained by boiling the aqueous carbon black suspension and cooling. Refers to the pH value of the material. The aggregate diameter of carbon black according to the present invention is 30 nm or less, and the value (SD / Dag) obtained by dividing the standard deviation (SD) of the aggregate diameter distribution by the average aggregate diameter (Dagg) is 0.4 or less. Must. SD / Dagg is preferably 0.38 or less. SD / Dagg is 0.4
When the ratio exceeds the above range, the glossiness and scratch resistance of the obtained recorded matter are remarkably deteriorated. When the aggregate diameter is 30 nm or less and the SD / Dag is 0.4 or less in carbon black,
That is, it means that the size of the aggregate of carbon black is small, the distribution of the aggregate is extremely sharp, and the size of the particles is uniform. in this way,
In the present invention, the use of carbon black having a small primary particle size, a low structure and an extremely sharp distribution of aggregates achieves an excellent effect for the first time.

The aggregate size distribution of carbon black in the present invention is defined as a concentration at which the aggregates do not overlap each other when photographed by a transmission electron microscope (TEM), and the carbon black is sufficiently dissolved in chloroform. A TEM photograph (30,000 times magnification after enlargement) of the diluted and dispersed dispersion developed and dried on a mesh with a collodion membrane and photographed.
Is input to a scanner, digitized, and the distribution of the diameter (equal area circle diameter) of a circle having an area equal to the area of each aggregate extracted by computer image analysis is referred to as the average aggregate diameter. It refers to the arithmetic average diameter (number average value) obtained from the obtained aggregate diameter distribution. Specific examples of carbon black as described above include Mitsubishi Carbon Black # 9
100, # 9180 (both manufactured by Mitsubishi Chemical Corporation) and the like. The carbon black used in the present invention may be a powdery product or a granular product. Further, as the carbon black used in the recording liquid of the present invention, those obtained by chemically treating the above-described carbon black (oxidation treatment, fluorination treatment, etc.), dispersants, surfactants, etc. (A grafting treatment, a dispersant adsorbed in advance before dispersion, etc.) may be used. The amount of carbon black used in the recording liquid according to the present invention is 1 to 20 with respect to the total weight of the recording liquid.
%, But preferably 3 to 10% by weight.

Various additives known as ink jet recording liquids can be used in the aqueous pigment dispersion according to the present invention. For example, a dispersant may be used. The dispersant that can be used is not particularly limited as long as it is a known dispersant, but various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymer dispersions Agents and the like. Since the scratch resistance and gloss of the obtained recorded matter are extremely good, a polymer dispersant is particularly preferably used. As anionic surfactants, fatty acid salts, alkyl sulfate salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates,
Alkyl sulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl sulfates, polyoxyethylene alkyl aryl sulfates, alkane sulfonates, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl Phosphate esters, N
-Methyl-N-oleoyl taurate, α-olefin sulfonates and the like.

Among the nonionic surfactants, nonionic additives having an ethylene oxide structure or a propylene oxide structure are preferred in terms of storage stability and printing density, and among them, those having an HLB of 9 to 17 are more preferable. preferable. Among them, those having an HLB of 10 to 16 are particularly preferable. Specifically, polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, polyoxyethylene derivatives, ethylene oxide-propylene oxide block copolymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene Ethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, poly (ethylene sorbitol fatty acid esters), glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines, etc. . Examples of the cationic surfactant and the amphoteric surfactant include alkylamine salts, quaternary ammonium salts, alkylbetaines, and amine oxides.

As the polymer dispersant, a polymer dispersant containing both a hydrophobic functional group and a hydrophilic functional group can be used to improve the dispersion stability of carbon black, the water resistance of the recorded matter obtained, and the abrasion resistance. Is preferred. Specific examples of the polymer dispersant used in the present invention include an anionic high-molecular weight dispersant having an anionic functional group selected from a carboxylic acid (salt) group, a sulfonic acid (salt) group, and a phosphoric acid (salt) group. Molecules can be used particularly preferably. Specific examples of such an anionic polymer include styrene, α-methylstyrene, aliphatic hydrocarbon and / or aromatic hydrocarbon ester of (meth) acrylic acid, and aliphatic hydrocarbon and / or aromatic hydrocarbon of maleic acid. A hydrophobic vinyl monomer unit such as an aromatic hydrocarbon ester;
Aqueous acrylic resins containing anionic vinyl monomer units such as (meth) acrylic acid, maleic acid, 2-acrylamido-2-methylpropanesulfonic acid and / or salts thereof as constituents are preferred. One of these polymer dispersants may be used alone, two or more thereof may be used in combination, or another known polymer dispersant may be used in combination.

Commercially available polymer dispersants as described above include styrene-acrylic acid copolymers such as Joncryl 67, 678, 680, 682, 6
90 and / or salt thereof, Joncryl 52, 57, 6
0, 62, 63, 70, 354, 501, 6610 (all manufactured by Johnson Polymer Co., Ltd.) and the like. These polymer dispersants can be obtained in the form of resin pellets, solutions, emulsions and the like. The weight-average molecular weight of the polymer dispersant used in the present invention is preferably 50,000 or less from the viewpoint of ejection stability, more preferably 15,000 or less, and particularly preferably 10,000 or less. preferable. Further, these compounds can be used in the form of organic amine salts such as mono / di / triethanolamine. The addition amount of the dispersant contained in the recording liquid according to the present invention is preferably 1 to 100 parts by weight to 100 parts by weight of carbon black,
More preferably 1 to 70 parts by weight, even more preferably 5 to 6 parts by weight.
0 parts by weight. If the amount is less than 1 part by weight, not only the storage stability of the obtained recording liquid is deteriorated, but also the scratch resistance of the recorded matter may be insufficient. If the amount exceeds 60 parts by weight, the ejection stability of the obtained recording liquid tends to deteriorate.

In the aqueous pigment dispersion of the present invention, water is used as an aqueous medium, but it is preferable to add a water-soluble organic solvent to water. Examples of the water-soluble organic solvent include ethylene glycol, propylene glycol, 1,3-propanediol, butylene glycol, diethylene glycol, triethylene glycol, and polyethylene glycol (specific examples: # 200, # 300, # 400, #, manufactured by Wako Pure Chemical Industries, Ltd.).
4000, # 6000), glycerin, ethylene glycol adduct of glycerin (specific examples: products of Lipochemical Co., Ltd.)
Liponic EG-1), alkyl ethers of the above glycols (diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, diethylene glycol monopropyl ether, triethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, polyethylene) Glycol monopropyl ether,
Polyethylene glycol monobutyl ether, polyethylene glycol monostearyl ether, etc.), N-methylpyrrolidone, 1,3-dimethylimidazolinone, thiodiglycol, 2-pyrrolidone, sulfolane, dimethylsulfoxide, diethanolamine, triethanolamine, methanol, ethanol, isopropanol , Neopentyl alcohol, trimethylolpropane, 2,
2-dimethylpropanol and the like.

The amount of the water-soluble organic solvent contained in the aqueous pigment dispersion of the present invention is preferably in the range of 5 to 30% by weight, more preferably 5 to 20% by weight, and more preferably 8 to 20% by weight. Particularly preferred. The aqueous pigment dispersion of the present invention contains p
An H adjuster, a viscosity adjuster, a surface tension adjuster, a preservative, a water-soluble resin, a fungicide, a bactericide, a chelating resin, a discharge improver such as a nitrogen-containing compound, and the like may be added as necessary. .
Each of these carbon blacks, dispersants, organic solvents, additives, etc., may be used alone, but in some cases two or more may be used in combination to further enhance the effect. Can be.

As a dispersing machine for preparing the recording liquid according to the present invention, besides a ball mill, a roll mill and a sand grind mill, a jet mill such as a nanomizer and an ultimizer which can be pulverized without using a medium is used. A sand grind mill or a jet mill with less contamination from media is preferred. After this grinding and dispersion treatment, coarse particles are removed using a filter or a centrifuge. Further, since the milling and dispersion treatment can be efficiently performed by preparing a high concentration, the treatment liquid prepared at a high concentration may be diluted with an aqueous medium to adjust the concentration of the recording liquid.

The average dispersed particle size of the carbon black dispersed in the recording liquid according to the present invention is preferably 200 nm or less, more preferably 150 nm or less, and further preferably 1 nm or less.
The thickness is preferably 30 nm or less. The smaller the dispersed particle diameter, the higher the print density of the obtained recorded matter tends to be.
The average dispersion particle size distribution is preferably such that the standard deviation is 70 nm or less, preferably 5 to 60 nm, and more preferably 10 to 50 nm, in terms of storage stability, ejection stability, and recording density of the recording liquid. Further, the maximum dispersed particle diameter of carbon black is preferably 5 μm or less from the viewpoint of storage stability and ejection stability of the obtained dispersion. However, in the present invention, the average dispersed particle size and the dispersed particle size distribution of the water-insoluble coloring material in the recording liquid are determined by a submicron particle analyzer N4S.
(A product of Coulter) and a value measured by a light scattering method. The recording liquid obtained in the present invention can be used for all types of ink jet recording methods (on-demand method,
It can be used for continuous type, piezo type and thermal type. The recording sheet used in the present invention is an ink jet recording sheet in which an ink receiving layer is provided on at least one surface of a support such as paper or a resin film. The support according to the present invention is mainly composed of a wood pulp such as a chemical pulp, a mechanical pulp, or a waste paper pulp and a conventionally known pigment, and has a binder, a sizing agent, a fixing agent, a retention agent, a cationizing agent, a paper strength. Various additives such as a strengthening agent are mixed using one or more kinds, and a base paper manufactured by various devices such as a fourdrinier paper machine, a round paper machine, a twin wire paper machine, and a coat layer is further provided on the base paper. Art paper, coated paper, and cast-coated paper are also included.

A resin layer of polyolefin or the like may be provided on the base paper, or polyethylene, polypropylene,
It is also possible to apply the present invention to a film material of a synthetic resin such as polyester, nylon, rayon, polyurethane, polyethylene terephthalate, or a mixture thereof, or to a sheet formed from the synthetic resin. These supports are appropriately selected in consideration of the purpose of recording, the use of the recorded image, the adhesion to the ink receiving layer, and the like.

The structure of the ink receiving layer of the recording sheet according to the present invention is not particularly limited, but a white pigment represented by silica or alumina is generally dispersed in a binder resin mainly composed of a water-soluble polymer. It can be obtained by applying the cured product to the surface of a support. In the recording sheet used in the present invention, the value obtained by dividing the average particle diameter of the white pigment constituting the receiving layer by the average dispersed particle diameter of the carbon black in the recording liquid according to the present invention is preferably less than 2, more preferably It is better to be less than 1.5, more preferably less than 1. If the above value exceeds 2, the gap between the white pigments becomes large, and when the printed recording liquid penetrates the ink receiving layer, the carbon black in the recording liquid simultaneously penetrates the ink receiving layer. And the print density may be insufficient. Here, the average particle diameter of the white pigment means a scanning electron micrograph (magnification 30,000 after enlargement) of the surface of the recording sheet input to a scanner, digitized, and extracted by computer image analysis. The arithmetic mean diameter (number average) obtained by calculating the distribution of the diameter (equal area circle diameter) of a circle having an area equal to the area of each particle portion. The average particle diameter of the white pigment constituting the receiving layer of the recording sheet according to the present invention is preferably 100 nm or less.

As the white pigment constituting the ink receiving layer according to the present invention, any conventionally known white pigment can be used. For example, light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, synthetic amorphous silica, water Aluminum oxide, lithopone, zeolite, hydrohaloysite, magnesium hydroxide, alumina sol, fumed silica, colloidal silica, and the like, and further, aluminum oxide hydrate, zirconium oxide hydrate, tin oxide hydrate, and the like. Colloidal silica coated with a cationic modifier composed of metal oxide hydrate can also be used. These white pigments may be used alone or in combination of two or more.

Examples of binders constituting the ink receiving layer together with the white pigment include polyvinyl alcohol, vinyl acetate, oxidized starch, etherified starch, cellulose derivatives such as carboxymethylcellulose and hydroxyethylcellulose, casein, gelatin, soybean protein, and silyl-modified polyvinyl alcohol. And conjugated diene polymer latexes such as maleic anhydride resin, styrene-butadiene copolymer, methyl methacrylate-butadiene copolymer,
Polymers and copolymers of acrylic esters and methacrylic esters, acrylic polymer latexes such as acrylic acid and methacrylic acid polymers and copolymers, vinyl polymer latexes such as ethylene vinyl acetate copolymer, or Functional group-modified polymerization latex by a functional group-containing monomer such as a carboxyl group of these various polymers, melamine resin, aqueous binders such as thermosetting synthetic resin such as urea resin, polymethyl methacrylate, polyurethane resin, Examples thereof include synthetic resin binders such as unsaturated polyester resins, vinyl chloride-vinyl acetate copolymers, polyvinyl butyral, and alkyd resins. These binders may be used alone,
Two or more kinds may be used in combination.

For the purpose of fixing coloring materials such as dyes and pigments, conventionally known cationic organic substances can be used in combination without any particular limitation. Specific examples of such cationic organic substances include amines such as quaternary ammonium salts and alkylamines and amides. Such a polymer having a cationic residue in the side chain can also be used as the cationic organic substance. Further, as other additives to the ink receiving layer of the recording sheet, pigment dispersants, thickeners, flow improvers, defoamers, foam inhibitors, release agents, foaming agents, penetrants, coloring dyes, A coloring pigment, a fluorescent whitening agent, an antioxidant, an antiseptic, a fungicide, a waterproofing agent, a wet paper strength enhancer, and the like can also be appropriately compounded.

The method for coating and impregnating the ink receiving layer of the recording sheet of the present invention includes various blade coaters, roll coaters, air knife coaters, bar coaters, rod blade coaters, curtain coaters, short dwell coaters,
Various devices such as a size press can be used.

The ink receiving layer of the recording sheet used in the present invention preferably forms a porous layer, and the average pore diameter of the porous layer is determined by the average of carbon black in the recording liquid according to the present invention. It is preferable that the value divided by the dispersed particle diameter is less than 2, more preferably less than 1.5, and even more preferably less than 1. When the value obtained by dividing the average pore diameter of the porous layer by the dispersed particle diameter of carbon black in the recording liquid exceeds 2, when the printed recording liquid penetrates the ink receiving layer,
Carbon black in the recording liquid also penetrates into the ink receiving layer at the same time, and there is a possibility that the printing density becomes insufficient because the dye does not remain on the sheet. The average pore diameter referred to here is a value obtained by inputting a scanning electron micrograph (magnification: 30,000 times after enlargement) of the surface of the recording sheet to a scanner, digitizing the image, and extracting each void portion by computer image analysis. The arithmetic mean diameter (number average) obtained by calculating the distribution of the diameter (equal area circle diameter) of a circle having an area equal to the area.

The present invention is particularly useful when recording on a recording sheet having a glossy surface, and the glossiness of the recording sheet surface at 60 ° is 10 gloss units or more, preferably 30 gloss units or more. preferable. When the inkjet recording liquid of the present invention is applied to such a recording sheet, a recorded matter having extremely good gloss can be obtained. The glossiness referred to here is in accordance with DIN 67 530 (German Industrial Standard) measured using a haze-gloss reflectometer manufactured by Big Gardner Co., Germany.
It refers to a value expressed with a reflection index of 1.567 on a color glass standard plate as 100 gloss units.

As such a recording sheet, any commercially available glossy paper for ink jet recording satisfying the above conditions can be used without any particular limitation. For example, glossy paper for ink jet recording manufactured by Seiko Epson Corporation can be used. Examples of the film include MJA4SP6, Professional Photo Paper PR101 manufactured by Canon Inc., and Photo Glossy Film HG201 manufactured by Canon Inc.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the invention. In the following examples, “parts” and “%” are based on weight. (Production example of carbon black) Carbon black is N
The oil was produced according to the usual oil furnace method except that a raw oil containing less a, Ca and S was used, and water treated with an ion-exchange resin was used as a reaction stopping water. Table 1 shows the physical property values of the obtained carbon black.

Here, the size distribution of aggregates of carbon black was measured as follows. A test tube is filled with a very small amount of carbon black, which is slightly colored with chloroform, and placed in an ultrasonic disperser (a wideband ultrasonic generator USV-50).
Using a 0 V, manufactured by Ultrasonic Industry Co., Ltd.), the dispersion was performed for 10 minutes at an output of 400 W using a vibrator of 200 kHz. This dispersion is meshed with a collodion membrane (200 mesh,
The solution was dropped on Nissin EMI Co., Ltd., dried, and photographed with a transmission electron microscope (H7000, manufactured by Hitachi, Ltd., acceleration voltage 100 kV). The obtained TEM photograph (magnification: 150,000 times after enlargement) is scanned with a scanner (GT-9500, manufactured by Seiko Epson Corporation, resolution: 20).
0DPI) and digitized, then 1624 × 2
The image of 334 pixels is divided into four parts, and the image analysis system “MI
NS "(manufactured by Mitsubishi Chemical Corporation) and processed by computer image processing. The distribution of the diameter (equivalent circular diameter) and the arithmetic mean diameter (number average) of the circles having an area equal to the area of each automatically extracted aggregate were determined to be the aggregate diameter distribution and the average aggregate diameter, respectively. Example 1 (Preparation of recording liquid)

[0032]

Table 1 Composition of recording liquid Amount used (parts) Carbon black A 2.10 Ammonium salt of Joncryl 679 ^* 0.63 (as solid content) Diethylene glycol 1.05 Deionized water 17.22 Total 21.00 ( ^* A styrene-acrylic acid-based copolymer (manufactured by Johnson Polymer Co., Ltd., acid value: 215, weight-average molecular weight: 8500) Each of the above components is placed in a cylindrical stainless steel container and sanded together with 74.5 g of zirconia beads having an average diameter of 0.5 mm. Dispersion treatment was performed for 11 hours using a grinder. To the obtained liquid, 3.5 parts of diethylene glycol monobutyl ether (DEGB) and 10.5 parts of ion-exchanged water were further added. This solution was Pressure filtration was performed using a 5C filter paper, and the liquid obtained here was used as a recording liquid. (Measurement of Dispersion Particle Size Distribution) The obtained recording liquid is diluted with ion-exchanged water, and the resulting mixture is subjected to a particle size distribution analyzer (particle analyzer N4S (Cou).
lter product))).

[Table 2] Measurement conditions Temperature = 25 degree Viscosity = 0.894 cP Refractive Index = 1.333 Angle = 90.0 degrees Sample Time = 13.5 micro-sec Pre-scale = 2 Run Time = 60 seconds Three times when measured under the above measurement conditions The average value of the measurements was taken as the value of the average dispersed particle size of the recording liquid. The average dispersion particle diameter of the recording liquid obtained in Example 1 was 123 nm. (Ejection Test) Using an ink jet printer (manufactured by Seiko Epson Corporation), a printing test was performed on the recording liquid obtained by the method described in the above Example. A glossy film for ink jet recording MJA4SP6 (manufactured by Seiko Epson Corporation) was used as a recording sheet. The results of the discharge test are classified as follows, and are shown in Table 2 below. …: Stable and good dischargeability without clogging was observed, and good printed matter was obtained. Δ: Some nozzle clogging occurred, and the printed matter was blurred. C: Nozzle clogging occurred, and ink could not be ejected. (Measurement of Average Pore Diameter of Recording Sheet and Average Particle Diameter of White Pigment) The average pore diameter of the ink receiving layer constituting the recording sheet and the average particle diameter of the white pigment were determined by a scanning electron microscope on the surface of the recording sheet. (SEM) Photograph (magnified 30,000 times after enlargement) was scanned with a scanner (Seiko Epson GT-9).
(500 type), digitized, and processed by computer image processing using an image analysis system “MINS” (manufactured by Mitsubishi Chemical Corporation). The arithmetic mean diameter (number average) of the diameter (equal area circle diameter) distribution of a circle having an area equal to the area of each void portion and each white pigment particle automatically extracted by MINS is obtained, and the average of each ink receiving layer is obtained. The pore diameter and the average particle diameter of the white pigment were used. Glossy film for ink jet recording MJA4SP6 (manufactured by Seiko Epson) has an average pore diameter of 30 n in the ink receiving layer.
m, the average particle diameter of the white pigment particles contained in the ink receiving layer was 50 nm. (Evaluation of Print Density) The density of the printed matter obtained in the above print test was measured using a Macbeth reflection densitometer (RD914).
The results are shown in Table 2 below. The higher the value, the better the print density. (Gloss evaluation) The gloss value (unit: gloss unit) of the printed matter obtained in the above printing test was measured using a haze-gloss reflectometer (manufactured by Big Gardner Co., Ltd.), and D
According to IN 67 530 (German Industrial Standard), a value was set with a reflection index of 1.567 on a black glass standard plate as 100 gloss units. The surface gloss value of the printing part is a reflection angle of 20.
Using the values in °, the results are shown in Table 2 below. The larger the value, the better the gloss. The glossy film for ink jet recording used in the printing test, MJ
When the surface gloss value of A4SP6 (non-printed portion) was evaluated by the gloss value at a reflection angle of 60 °, it was 48 gloss units.

(Scratch resistance test)
The printed surface of the "MJA4SP6" printed material obtained in the above printing test was rubbed with a metallic spatula, and the presence or absence of peeling of the printed surface was visually evaluated. The results were classified as follows and shown in Table 2 below.

…: There is no peeling of the printed surface, and the scratch resistance is excellent. Δ: The printed surface hardly peeled off, and the scratch resistance was good. X: The printed surface peeled off, causing a practical problem, and the scratch resistance was poor. Example 2 Instead of using the carbon black A used in Example 1, a recording liquid was prepared in the same manner as in Example 1 except that carbon black B having the physical properties shown in Table 1 below was used. Print evaluation was performed. The results are shown in Table 2 below. Example 3 A recording liquid was prepared in the same manner as in Example 1 except that the dispersion time was extended and the average dispersed particle diameter was further reduced by the same method as in Example 1, and the printing evaluation was similarly performed. went. The results are shown in Tables 1 and 2 below.

Comparative Examples 1-2 The recording liquid was prepared in the same manner as in Example 1 except that carbon black A having the physical properties shown in Table 1 was used instead of carbon black A in Example 1. Is prepared,
The printing was evaluated in the same manner. The results are shown in Table 2 below.

As can be seen from Tables 1 and 2, in Examples 1 to 3 according to the present invention, carbon black having an extremely small average primary particle diameter, a very low DBP absorption and an extremely sharp aggregate diameter distribution was obtained. By using the recording liquid, the recording liquid obtained has excellent dischargeability, and at the same time, when subjected to ink jet recording on an ink jet recording sheet having a specific ink receiving layer, extremely excellent scratch resistance, gloss, and print density. It turns out that a thing is obtained. On the other hand, when recording was performed using a recording liquid using carbon black having an average primary particle diameter and / or DBP absorption outside the range of the present invention,
It can be seen that the glossiness and scratch resistance of the obtained recorded matter were extremely deteriorated (Comparative Examples 1 and 2).

[0037]

According to the present invention, when printing is performed on a recording sheet provided with a specific ink receiving layer using an inkjet recording liquid having excellent ejection stability, good print density and ink ejection properties are maintained. As it is, it is possible to provide an ink jet recording method capable of obtaining a printed matter having extremely excellent gloss and abrasion resistance, and its industrial utility value is extremely high.

[0038]

[Table 3]

[0039]

[Table 4]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) C09C 3/10 C09D 11/00 C09D 11/00 B41J 3/04 101Y (72) Inventor Hideyuki Hisa, Yokkaichi, Mie Prefecture 1 Toho-cho, Yokohama-shi F-term in Yokkaichi Office of Mitsubishi Chemical Corporation (reference) 2C056 EA13 FC01 FC06 2H086 BA15 BA33 BA41 BA45 BA55 BA59 BA60 4J037 AA02 CC13 CC16 CC17 DD05 DD17 DD24 EE43 FF15 4J039 AD03 AD09 AD10 AD12 BE14 EA33 EA35 EA36 EA38 EA44 FA02 GA24

Claims (8)

[Claims] 1. An aqueous pigment dispersion containing carbon black and water, wherein the carbon black has an average primary particle diameter of 18 nm or less and a DBP oil absorption of 120 cm ³ / cm ² .
100 g or less, the aggregate diameter is 30 nm or less, and the standard deviation (SD) of the aggregate diameter distribution is calculated as the aggregate diameter (Dagg)
An aqueous pigment dispersion, wherein the value (SD / Dagg) divided by is 0.4 or less. 2. The carbon black having an average dispersed particle size of 2
The aqueous pigment dispersion according to claim 1, wherein the dispersion is not more than 00 nm. 3. The aqueous pigment dispersion according to claim 1, wherein the aqueous pigment dispersion further contains a polymer dispersant. 4. An ink jet recording liquid using the aqueous pigment dispersion according to claim 1. 5. An ink jet recording method, comprising recording the aqueous pigment dispersion according to claim 1 on a recording sheet having an ink receiving layer provided on a support. 6. The ink jet recording method according to claim 5, wherein the glossiness of the recording sheet surface at 60 ° is 10 gloss units or more. 7. The recording sheet according to claim 1, wherein the ink receiving layer is a porous layer, and the value obtained by dividing the average pore diameter of the porous layer by the average dispersed particle diameter of carbon black in the recording liquid is less than 2. The ink jet recording method according to claim 5, wherein: 8. The ink receiving layer of a recording sheet contains a white pigment, and the value obtained by dividing the average particle diameter of the white pigment by the average dispersed particle diameter of carbon black in the recording liquid is less than 2. The inkjet recording method according to claim 5, wherein: