JP2003176427A - Ink set, inkjet recording method and recorded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink set capable of achieving the printing of an image having excellent reproducibility of the image and color. <P>SOLUTION: The ink set comprises a black ink composition and at least one or more colored ink compositions. The black ink composition comprises a pigment surface-treated so as to be dispersible and/or dissolvable in water without using a disperser, and water as a main solvent. The colored ink composition comprises a pigment, a macromolecular disperser for dispersing the pigment, and water as the main solvent. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink set having excellent color reproducibility and an inkjet recording method.

2. Background Art Ink jet recording method by ejecting droplets of an ink composition is a printing method for printing by adhering to a recording medium such as paper. This method is characterized in that it is possible to print a high-resolution, high-quality image at high speed with a relatively inexpensive device. Recently, a plurality of color ink compositions are prepared and a color image is formed by inkjet recording. In general, a color image is formed by three colors of a yellow ink composition, a magenta ink composition, and a cyan ink composition, four colors by further adding a black ink composition, and further by a color density in addition to the above four colors. It has been practiced to form a color image with six colors including a (light) cyan ink composition having a low color density and a (light) magenta ink composition having a low color density.

By mixing ink dots of such plural colors of ink, it is possible to print color images of various colors. When three types of ink dots of cyan color, magenta color, and yellow color are mixed and formed, a color image with low lightness (dark) can be printed.
For example, when cyan, magenta, and yellow color ink dots are mixed and formed in substantially equal amounts, black appears visually due to subtractive color mixing. The black thus expressed is called composite black.

In general, the recording medium is provided with a predetermined standard for the total amount of ink dots formed per unit area from the viewpoint of avoiding deterioration of image quality due to ink bleeding or the like. Such a standard value of the total amount of ink dots is called a normal ink duty limit value.

When composite black is used to print a color image of low brightness (dark), it is necessary to form three types of ink dots. In this case, the ink duty limit value may be exceeded, resulting in deterioration of image quality. Therefore, it has been practiced to provide a color printer with black ink and use ink dots of black ink alone instead of composite black.

However, in general, the dots of black ink are very conspicuous, so that the dots may be conspicuous depending on the image to be formed, and the image may have a granular feeling. Also, when an image is formed using dots of black ink, a blank remains in the image,
So-called white spots may occur. Therefore, a printing system using a black ink that can exhibit excellent image reproducibility and color reproducibility is desired.

[0007]

SUMMARY OF THE INVENTION The present inventors have recently used a self-dispersion type surface-treated pigment as a colorant in a black ink composition and dispersed it with a polymer dispersant as a colorant in an chromatic color ink composition. By using pigments, in color printed images that require black expression,
It was found that excellent image reproducibility and color reproducibility can be realized. The present invention is based on such findings. Therefore, an object of the present invention is to provide an ink set and an inkjet recording method capable of realizing printing of an image excellent in image reproducibility and color reproducibility, and a recorded matter recorded by using these. .

Therefore, the ink set according to the present invention is an ink set containing a black ink composition and at least one or more chromatic color ink compositions, wherein the black ink composition is dissolved in water without a dispersant. Distributed and /
Alternatively, the surface-treated pigment capable of dissolving and at least water as a main solvent are contained, and the chromatic ink composition has a pigment, a polymer dispersant for dispersing the pigment, and water as a main solvent. It is characterized by comprising at least and.

The ink jet recording method according to the present invention is an ink jet recording method in which droplets of an ink composition are ejected and the droplets are adhered to a recording medium for printing, and the ink composition is a black ink composition. And a chromatic ink composition capable of printing an achromatic color when combined with each other, and the black ink composition is a surface treatment capable of being dispersed and / or dissolved in water without a dispersant. A pigment and at least water as a main solvent, wherein the chromatic ink composition contains at least a pigment, a polymer dispersant for dispersing the pigment, and water as a main solvent. When the ink dots printed by combining the chromatic color ink composition are achromatic, the combination of the chromatic color ink composition Instead allowed, it is characterized in that to print the dots by ejecting a black ink composition.

According to the ink set of the present invention, the occurrence of so-called white spots which may occur when printing on plain paper,
Generation of color bleed can be prevented. By using the ink set of the present invention or applying the recording method of the present invention, it is possible to print an image excellent in image reproducibility and color reproducibility.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Ink Set The ink set according to the present invention is used in a recording system using an ink composition. Examples of the recording method using the ink composition include an inkjet recording method, a recording method using a writing instrument such as a pen, and various other printing methods. The ink set according to the present invention is preferably used in an inkjet recording method.

The ink set according to the present invention comprises a black ink composition and at least one chromatic color ink composition. Here, the chromatic color ink composition means an ink composition exhibiting a chromatic color, that is, a color having saturation, and is capable of performing so-called color printing. This is used in contrast to a black ink composition that prints only achromatic colors that have no saturation. In addition, as the chromatic color here, for example,
Colors such as cyan, magenta, and yellow are included.

According to a preferred embodiment of the present invention, it is preferable that the chromatic color ink composition comprises at least two kinds of chromatic color ink compositions capable of printing an achromatic color by combining with each other. Here, "printing an achromatic color by combining with each other" means a case where an achromatic color can be expressed by combining each ink dot formed by a plurality of chromatic color ink compositions used. As long as an achromatic color can be expressed as described above, the concentration and the usage amount of each chromatic color ink composition are not particularly limited.

According to a more preferred aspect of the present invention, the chromatic ink composition preferably comprises a cyan ink composition, a magenta ink composition and a yellow ink composition, and more preferably the chromatic ink composition. The colored ink composition includes two types of cyan ink compositions having different color densities,
It is composed of two types of magenta ink compositions having different color densities and a yellow ink composition.

Black Ink Composition The black ink composition of the present invention contains at least a surface-treated pigment that can be dispersed and / or dissolved in water without a dispersant, and water as a main solvent.

The surface-treated pigment used in the pigment black ink composition is a surface-treated pigment in which at least one functional group of a carbonyl group, a carboxyl group, a hydroxyl group, or a sulfone group or a salt thereof is bonded to the surface. , And can be dispersed and / or dissolved in water without a dispersant. Specifically, it can be obtained by grafting a functional group or a molecule containing a functional group onto the surface of carbon black by physical treatment such as vacuum plasma or chemical treatment. In the present invention, the functional group to be grafted on one carbon black particle may be a single type or plural types. The kind and degree of the functional group to be grafted may be appropriately determined in consideration of the dispersion stability in the ink, the color density, the drying property on the front surface of the inkjet head, and the like.

In the present invention, the state in which the pigment is stably present in water without a dispersant is referred to as "dispersion and / or dissolution". There are many cases where it is difficult to clearly distinguish whether a substance is dissolved or dispersed.
In the present invention, as long as the pigment can stably exist in water without a dispersant, such a pigment can be used regardless of whether the state is dispersion or dissolution. Therefore, in this specification, a pigment that can stably exist in water without a dispersant is sometimes referred to as a water-soluble pigment, but it does not mean that even a pigment in a dispersed state is excluded.

The above-mentioned pigment used in the present invention can be obtained, for example, by the method described in JP-A-8-3498. It is also possible to use a commercially available product as the pigment, and a preferable example is Microjet CW1 manufactured by Orient Chemical Industry Co., Ltd.

In the present invention, the amount of the surface-treated pigment added to the black ink composition is preferably 1 to 30% by weight, more preferably 3 to 10% by weight.

Main Solvent and Other Components In the black ink composition according to the present invention, the main solvent is water. As the water, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water can be used. Further, it is preferable to use water that has been sterilized by ultraviolet irradiation, addition of hydrogen peroxide, or the like, because it is possible to prevent the generation of mold and bacteria when the ink composition is stored for a long period of time.

According to a preferred embodiment of the present invention, the black ink composition may further contain a water-soluble organic solvent as a penetrant. Examples of such a water-soluble organic solvent include methanol, ethanol, n-propanol, iso-propanol, n-butanol, and s.
ec-butanol, tert-butanol, iso-ptanol, monohydric alcohols such as n-pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether,
Diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t -Butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether,
Propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono- n
-Propyl ether, dipropylene glycol mono-i
Mention may be made of glycol monoalkyl ethers such as so-propyl ether.

Further, for example, glycol mono-n-butyl ether is particularly preferable.

Examples of such glycol mono-n-butyl ether include ethylene glycol mono-n
-Butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, or dipropylene glycol mono-n-butyl ether is preferred. These may be used in combination of two or more. According to the addition of these glycol mono-n-butyl ethers,
It is possible to improve the permeability of an ink composition containing a pigment that disperses and / or dissolves in water without the use of a dispersant as described above.

In the present invention, the amount of glycol mono-n-butyl ether added to the black ink composition is preferably 3 to 30% by weight, more preferably 5 to 10% by weight.

In the present invention, the black ink composition preferably further contains a 1,2-alkanediol. As such a 1,2-alkanediol, one selected from the group consisting of 1,2-alkanediols having 4 to 10 carbon atoms is preferable. in this case,
Two or more kinds of 1,2-alkanediols having different carbon numbers may be mixed and added. In a preferred embodiment of the present invention, the 1,2-alkanediol comprises 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and mixtures thereof. Selected from the group. These are more preferable because they have excellent penetrability into a recording medium. In a more preferred aspect of the present invention, the 1,2-alkanediol is 1,2-hexanediol, or 1,2-hexanediol.
Pentanediol is preferable, and 1,2-hexanediol is more preferable.

In the present invention, the black ink composition is
The 1,2-alkanediol is preferably contained in an amount of 1 to 10% by weight, more preferably 2 to 5% by weight, based on the total amount of the ink composition.

According to one more preferred embodiment of the present invention, the black ink composition comprises a glycol ether and a 1,2-alkanediol at the same time as a penetrating solvent.

According to a preferred embodiment of the present invention, the black ink composition further comprises a nonionic surfactant. Examples of such nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide. , And acetylene glycol-based surfactants described later. These may be used in combination of two or more.

According to a more preferred embodiment of the present invention, the black ink composition preferably further contains an acetylene glycol-based surfactant as the nonionic surfactant. In the present invention, preferred specific examples of the acetylene glycol-based surfactant include compounds represented by the following formula (a).

[0030]

[Chemical 1] [In the above formula, 0 ≦ m + n ≦ 50, R ¹ , R ² , R ³ , and R ⁴ are independently an alkyl group (preferably having 1 to 1 carbon atoms).
6 alkyl group]

Among the compounds represented by the above formula (a), 2,4,7,9-tetramethyl-5-decyne-4,7-diol and 3,6-dimethyl-4-octyne are particularly preferable. -3,6-diol, 3,5-dimethyl-1-hexyne-3-ol and the like can be mentioned. It is also possible to use a commercially available product as the acetylene glycol-based surfactant represented by the above formula (a), and specific examples thereof include Surfynol 82, 104, 440, 465, 485, or TG. (Available from Air Products and Chemicals. Inc.), Olfine STG, Olfine E101
0 (trade name) (above, manufactured by Nisshin Chemical Co., Ltd.) can be mentioned. These acetylene glycol surfactants may be used alone or in combination of two or more.

The amount of the nonionic surfactant added is preferably 0.1 to 5% by weight, and more preferably 0.5 to 2% by weight, based on the ink composition. When it is within the above range, bleeding can be further reduced in the printed matter.

According to one preferred embodiment of the present invention, the black ink composition further comprises a nonionic surfactant and a water-soluble organic solvent as a penetrant.

According to a preferred embodiment of the present invention, the black ink composition preferably contains a polyol in order to prevent clogging of the nozzles of the ink jet recording head. As such polyols, water-soluble polyols are preferable, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, 1, 3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, mesoerythritol, pentaerythritol, thiodiene Examples thereof include glycol, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, trimethylolethane and trimethylolpropane. Also, 2-pyrrolidone, N-
It is also possible to use laclams such as methyl-2-pyrrolidone and ε-caprolactam, and ureas such as urea, thiourea, ethyleneurea and 1,3-dimethylimidazolidinone. Furthermore, as monosaccharides, disaccharides, oligosaccharides and polysaccharides, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, (sorbit), maltose,
Cellobiose, lactose, sucrose, trehalose, maltotriose and the like can also be added. Furthermore, derivatives of these sugars can be used, and examples thereof include reducing sugars, oxidizing sugars, amino acids, and thiosugars of the aforementioned sugars. Of these, sugar alcohols are particularly preferable, and specific examples thereof include maltitol, sorbitol and the like. In addition, commercially available products, HS-500, HS
-300 etc. (manufactured by Hayashibara Biochemical Research Institute) may be obtained and used. You may use these in mixture of 2 or more types.

The amount of addition of these anti-clogging components is 1
-40 wt% is preferable, and 1-30 wt% is more preferable. These components are preferably added together with other ink additives in an addition amount such that the ink viscosity becomes 25 cPs or less at 25 ° C.

The black ink composition according to the present invention contains other optional components such as antiseptics, antifungal agents, pH adjusting agents, antioxidants, conductivity adjusting agents and surface tension agents in order to improve its various properties. It may further comprise a regulator or an oxygen absorber.

Chromatic Color Ink Composition The chromatic color ink composition of the present invention contains at least a pigment, a polymer dispersant for dispersing the pigment, and water as a main solvent.

In the chromatic color ink composition according to the present invention, the pigment is an aqueous medium (water or water and a water-soluble organic solvent) which is mixed with a polymer dispersant (described later) or a polymer dispersant and another dispersant. It is in the state of being dispersed and / or dissolved in the mixture.

Examples of the pigment contained in the chromatic color ink composition of the pigments present invention, it is possible to use an organic pigment conventionally used in the ink composition for inkjet. Examples of organic pigments include azo pigments (including, for example, azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments, etc.), polycyclic pigments (eg, phthalocyanine pigments, perylene pigments,
Perinone pigment, anthraquinone pigment, quinacridone pigment, dioxazine pigment, thioindigo pigment, isoindolinone pigment, quinophthalone pigment, etc.), nitro pigment, nitroso pigment, or aniline black can be used.

When a cyan ink composition is used as the chromatic color ink composition, a cyan pigment is preferable as the colorant for the cyan ink composition. Examples of such a cyan pigment include C.I. I. Pigment Blue 15: 3,1
5: 4 and 60 are preferably used, and particularly C.I.
I. Pigment Blue 15: 3 is preferable.

When a magenta ink composition is used as the chromatic color ink composition, a magenta pigment is preferable as the colorant for the magenta ink composition. Examples of such magenta pigments include C.I. I. Pigment Red 122, 202, 209 and C.I. I. Pigment Violet 19 and the like are preferably used, and particularly C.I. I.
Pigment Red 122 is preferred.

When a yellow ink composition is used as the chromatic color ink composition, a yellow pigment is preferable as the colorant for the yellow ink composition. Examples of such a yellow pigment include C.I. I. Pigment Yellow 7
4,93,109,110,128,138,150,
151,154,155,180,185 etc. are mentioned.

These cyan pigments, magenta pigments and yellow pigments may be used alone or in combination of two or more.

According to a preferred embodiment of the present invention, the chromatic color ink composition comprises a yellow ink composition, two magenta ink compositions having different color densities, and two cyan ink compositions having different color densities. It may consist of
Here, the two types of magenta ink compositions having different color densities are a magenta ink composition having a higher density and a magenta ink composition having a lower density (hereinafter may be referred to as a light magenta ink composition). Consists of. Further, the two types of cyan ink compositions having different color densities include a cyan ink composition having a higher density and a cyan ink composition having a lower density (hereinafter sometimes referred to as a light cyan ink composition). . The light magenta ink composition and the light cyan ink composition can be prepared by appropriately selecting the pigment and other components and appropriately changing the blending amount thereof to reduce the color density.

Further, as the chromatic color ink composition, a color ink composition other than the cyan, magenta or yellow ink composition, for example, an orange ink composition or a green ink composition may be used, and the pigments used therein. As C.I. I. Pigment Orange 36,43
Orange pigments such as C.I. I. Pigment Green 7,3
Green pigments such as 6 are listed.

The content of the pigment in the chromatic color ink composition is preferably 0.5 to 10 with respect to the ink composition.
%, More preferably 1 to 7% by weight.

Polymer Dispersant In the present invention, preferred examples of the polymer dispersant include:
Natural polymers are listed, and specific examples thereof include glue,
Proteins such as gelatin, casein, albumin;
Natural rubbers such as gum arabic and tragacanth; glucosides such as sabonine; alginic acid derivatives such as alginic acid and propylene glycol alginate, triethanolamine alginate, ammonium alginate; cellulose derivatives such as methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose and ethyl hydroxy cellulose. And so on.

Further, another preferable example of the polymer dispersant is a synthetic polymer, and specific examples thereof include polyvinyl alcohols; polyvinylpyrrolidones; polyacrylic acid, acrylic acid-acrylonitrile copolymer. ,
Acrylic resins such as potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid alkyl ester copolymer; styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer Styrene-acryl such as polymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid-acrylic acid alkyl ester copolymer Resin; Styrene-maleic acid copolymer; Styrene-maleic anhydride copolymer; Vinyl naphthalene-acrylic acid copolymer; Vinyl naphthalene-maleic acid copolymer; Vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinyl Ethylene copolymer, vinyl acetate-maleic acid Examples thereof include vinyl acetate-based copolymers such as stell copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers, and salts thereof.

Of these, a copolymer of a monomer having a hydrophobic group and a monomer having a hydrophilic group, and a polymer composed of a monomer having both a hydrophobic group and a hydrophilic group in its molecular structure are preferable. . Examples of the above salts include diethylamine, ammonia, ethylamine, triethylamine,
Examples thereof include salts with propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, triethanolamine, diethanolamine, aminomethylpropanol, morpholine and the like. The weight average molecular weight of these copolymers is preferably 3,000 to 30,000, and more preferably 5,000 to 1
It is 5,000.

In the present invention, other dispersants that can be used in combination with the polymer dispersant include ordinary water-soluble ionic or nonionic surfactants.
Among these, for example, as the anionic surfactant, higher fatty acid salt, higher alkyl dicarboxylic acid salt, higher alcohol sulfate ester salt, higher alkyl sulfonate salt, condensate of higher fatty acid and amino acid, sulfosuccinate ester salt, naphthenic acid Examples thereof include salts, liquid fatty acid sulfate ester salts, and alkylallyl sulfonates. Examples of cationic surfactants include aliphatic amine salts, quaternary ammonium salts, sulfonium salts, phosphonium salts and the like, and examples of amphoteric surfactants include polyacrylamide. Examples of the nonionic surfactants include fatty acid esters of polyoxy compounds and polyethylene oxide condensates. In the present invention,
Two or more kinds of these dispersants may be used in combination.

In the present invention, the amount of these dispersants added is 35 with respect to the pigment used in the chromatic color ink composition.
To 90% by weight, more preferably 50 to 90% by weight.

Main Solvent and Other Components In the present invention, the main solvent of the chromatic color ink composition is water. As the water, pure water such as ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, or ultrapure water can be used. Further, it is preferable to use water that has been sterilized by ultraviolet irradiation, addition of hydrogen peroxide, or the like, because it is possible to prevent the generation of mold and bacteria when the ink composition is stored for a long period of time.

According to a preferred embodiment of the present invention, the chromatic color ink composition can further comprise a water-soluble organic solvent as a penetrant.

As such a water-soluble organic solvent, for example, methanol, ethanol, n-propanol, is
o-Probanol, n-butanol, sec-butanol, tert-butanol, iso-ptanol, n-
Monohydric alcohols such as pentanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol Mono-i
So-propyl ether, diethylene glycol mono-
iso-propyl ether, ethylene glycol mono-
n-butyl ether, ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono -N
-Propyl ether, propylene glycol mono-is
Examples thereof include glycol monoalkyl ethers such as o-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether and dipropylene glycol mono-iso-propyl ether.

Furthermore, for example, glycol mono-n-butyl ether is particularly preferable.

Examples of such glycol mono-n-butyl ether include ethylene glycol mono-n.
-Butyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, propylene glycol mono-n-butyl ether, or dipropylene glycol mono-n-butyl ether is preferred. These may be used in combination of two or more.

The content of glycol mono-n-butyl ether is preferably 0.5 based on the chromatic color ink composition.
-20% by weight, more preferably 1-10% by weight.

According to one preferred embodiment of the present invention, the chromatic ink composition further comprises a nonionic surfactant and the water-soluble organic solvent described above as a penetrant. Further, both the black ink composition and the chromatic color ink composition that compose the ink set according to the present invention further comprise a nonionic surfactant and a water-soluble organic solvent as a penetrant at the same time. Is more preferable. With such an ink set, an image with more excellent color reproducibility can be printed.

In the present invention, the chromatic color ink composition preferably further contains a 1,2-alkanediol. As such a 1,2-alkanediol, one selected from the group consisting of 1,2-alkanediols having 4 to 10 carbon atoms is preferable. in this case,
The 1,2-alkanediol may be mixed and added.
In a preferred embodiment of the invention, the 1,2-alkanediol is the group consisting of 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and mixtures thereof. To be selected. These are more preferable because they have excellent penetrability into a recording medium. In a more preferred embodiment of the present invention,
The 1,2-alkanediol is preferably 1,2-hexanediol or 1,2-pentanediol, and more preferably 1,2-hexanediol.

In the present invention, the chromatic color ink composition preferably contains the 1,2-alkanediol in the range of 1 to 10% by weight, more preferably 2 to 10% by weight based on the total amount of the ink composition. It is contained in the range of 5% by weight.

According to a preferred embodiment of the present invention, the chromatic color ink composition further comprises a nonionic surfactant. Examples of such nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, polyoxyethylene alkylamine, polyoxyethylene alkylamide. , And acetylene glycol-based surfactants described later. These may be used in combination of two or more. Further, according to a more preferable aspect of the present invention, it is preferable that the chromatic color ink composition further contains an acetylene glycol-based surfactant as the nonionic surfactant. Examples of such an acetylene glycol-based surfactant include the same ones as described above in the section of the black ink composition.

According to a preferred embodiment of the present invention, the chromatic color ink composition preferably contains a polyol in order to prevent clogging of the nozzles of the ink jet recording head. As such polyols, water-soluble polyols are preferable, and examples thereof include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, 1, 3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, mesoerythritol, pentaerythritol, thiodiene Glycol, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, trimethylolethane, trimethylolpropane, pentaerythritol And the like. Also,
It is also possible to use laclams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and ε-caprolactam, and ureas such as urea, thiourea, ethyleneurea and 1,3-dimethylimidazolidinone. Furthermore, as monosaccharides, disaccharides, oligosaccharides and polysaccharides, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, (sorbit), maltose, cellobiose, lactose, sucrose, trehalose, maltotris. Aus or the like can also be added. Furthermore, derivatives of these saccharides can be used, and examples thereof include reducing sugars, oxidizing sugars, amino acids, and thiosugars of the aforementioned sugars. Of these, sugar alcohols are particularly preferable, and specific examples thereof include maltitol, sorbitol and the like. In addition, commercially available products such as HS-500 and HS-300 (manufactured by Hayashibara Biochemical Laboratories) may be obtained and used. You may use these in mixture of 2 or more types.

The amount of addition of these anti-clogging components is 1
-40 wt% is preferable, and 1-30 wt% is more preferable. These components are preferably added together with other ink additives in an addition amount such that the ink viscosity becomes 25 cPs or less at 25 ° C.

The chromatic color ink composition according to the present invention has other optional components, for example, in order to improve its various properties.
The composition may further contain an antiseptic agent, an antifungal agent, a pH adjusting agent, an antioxidant, a conductivity adjusting agent, a surface tension adjusting agent, an oxygen absorbing agent and the like.

In the present invention, the ink composition containing a polymer dispersant and a pigment is, for example, a pigment, a polymer dispersant or a polymer dispersant and another dispersant, and water as a main solvent. Prepared by stirring and mixing with, for example, a bead mill, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, or a mill. can do.

Recording Method According to another aspect of the present invention, there is provided an ink jet recording method in which droplets of an ink composition are ejected and the droplets are adhered to a recording medium to perform printing, wherein the ink composition is black. Using the ink composition and at least two or more chromatic color ink compositions capable of printing an achromatic color when combined with each other, the black ink composition can be dispersed and / or dissolved in water without a dispersant. Surface-treated pigment,
It comprises at least water as a main solvent, wherein the chromatic ink composition comprises at least a pigment, a polymer dispersant for dispersing the pigment, and water as a main solvent. Yes, and when the ink dots printed by combining the chromatic color ink composition are achromatic, instead of the combination of the chromatic color ink composition,
An inkjet recording method is provided, which comprises printing the dots by ejecting a black ink composition.

According to a preferred embodiment of the present invention, it is preferable to use the ink composition in the ink set according to the present invention as the ink composition in the above method.

Further, according to the present invention, a recorded matter recorded by the above-mentioned recording method is also provided.

[0069]

The present invention will be described in detail below with reference to examples, but these do not limit the scope of the present invention.

Preparation of surface-treated pigment dispersion 100 g of MA100 (trade name) (manufactured by Mitsubishi Chemical Corporation) as dispersion K1 carbon black was mixed with 500 g of water,
It was crushed with a ball mill using zirconia beads. 1500 g of sodium hypochlorite (effective chlorine concentration: 12%) was added dropwise to the obtained ground stock solution, and the mixture was boiled for 10 hours to perform wet oxidation. The dispersion liquid obtained is used as a glass fiber filter paper G.
It filtered using A-100 (brand name) (made by Advantech Toyo Co., Ltd.), and the obtained filtration product was further washed with water. After re-dispersing a wet cake consisting of this filtration product in 5 kg of water, the reverse osmosis membrane has an electric conductivity of 2 mS.
Desalted / purified until the pigment concentration reaches 15% by weight, and the aqueous pigment dispersion (dispersion K
1) was obtained.

Dispersion K2 100 g of acidic carbon black having a primary particle size of 17 nm and a specific surface area of 200 m ² / g was mixed with 1 kg of water and pulverized with a ball mill using zirconia beads. 1400 g of sodium hypochlorite (effective chlorine concentration: 12%) was added dropwise to the obtained pulverized stock solution, and the mixture was reacted for 5 hours while pulverizing with a ball mill, and boiled for 4 hours with stirring to perform wet oxidation. The obtained dispersion stock solution was filtered using glass fiber filter paper GA-100 (trade name) (manufactured by Advantech Toyo Co., Ltd.), and the obtained filtered product was further washed with water. A wet cake consisting of this filtered product was redispersed in 5 kg of water, then desalted and purified by a reverse osmosis membrane until the electric conductivity became 2 mS / cm, and further concentrated until the pigment concentration became 15% by weight. An aqueous pigment dispersion (dispersion K2) was obtained.

Preparation of Polymer Dispersant Pigment Dispersion Dispersion Y1 As a yellow pigment, C.I. I. Pigment Yellow 74
100 g, 50 g of John Cryl J-62 (trade name) (manufactured by Johnson Polymer Co., Ltd.) as a dispersant for styrene-acrylic acid-based water-soluble resin, 2 g of potassium hydroxide, and 250 g of water were mixed, and then mixed in a ball mill with zirconia beads. Dispersion was performed for 10 hours. The resulting dispersion stock solution was filtered through a membrane filter (trade name) with a pore size of about 8 μm (manufactured by Japan Millipore Limited) to remove coarse particles, and then diluted with water to a pigment concentration of 15% by weight, and then dissolved in water. A yellow pigment dispersion liquid (dispersion liquid Y1) dispersed with a hydrophilic resin was obtained.

Dispersion M1 As a magenta pigment, C.I. I. Pigment Red 122
100 g, 30 g of Joncryl J-62 (trade name) as a dispersant for styrene-acrylic acid-based water-soluble resin, 2 g of potassium hydroxide, and 250 g of water were mixed, and dispersed for 10 hours by a ball mill using zirconia beads. . The resulting dispersion stock solution was filtered through a membrane filter (trade name) with a pore size of about 8 μm (manufactured by Japan Millipore Limited) to remove coarse particles, and then diluted with water to a pigment concentration of 15% by weight, and then dissolved in water. A magenta pigment dispersion liquid (dispersion liquid M1) dispersed with a hydrophilic resin was obtained.

Dispersion C1 As a cyan pigment, C.I. I. Pigment Blue 15: 3
100 g, 100 g of Jonkuryl J-62 (trade name) as a dispersant for styrene-acrylic acid-based water-soluble resin, 4.5 g of potassium hydroxide, and 250 g of water were mixed, and dispersed for 10 hours with a ball mill using zirconia beads. went. The resulting dispersion stock solution was filtered through a membrane filter (trade name) with a pore size of about 8 μm (manufactured by Japan Millipore Limited) to remove coarse particles, and then diluted with water to a pigment concentration of 15% by weight, and then dissolved in water. A cyan pigment dispersion liquid (dispersion liquid C1) dispersed with a hydrophilic resin was obtained.

Dispersion Y2 Resin Synthesis In a 1 L beaker, 40% by weight of n-butylmethacrylate, 5% by weight of n-butylacrylate, 2 styrene.
0% by weight, 15% by weight of 2-hydroxyethylmethacrylate, and 20% by weight of methacrylic acid were mixed so that the total amount would be 500 g, and 4 g of tert-butylperoxyoctoate as a polymerization initiator was added. Thus, a resin synthesis mixed solution was obtained. Next, 500 g of methyl ethyl ketone was placed in a 1 L flask, and the temperature was raised to 75 ° C. with stirring under a nitrogen atmosphere. The mixture was stirred at 75 ° C., and the above resin synthesis mixture was added dropwise thereto over 3 hours. Furthermore, the reaction was continued for 8 hours at 75 ° C. with stirring. After that, the obtained reaction mixture was naturally cooled to 25 ° C., and then methyl ethyl ketone was added and diluted so that the solid content became 50%. As a result, the acid value (KO
H) 130 and a resin solution having an average molecular weight of 15,000 were obtained.

Preparation of Dispersion Y2 As a yellow pigment, C.I. I. Pigment Yellow 74
100 g, 150 g of the resin solution obtained above, 70 g of a 5% aqueous potassium hydroxide solution, and 650 g of ultrapure water purified by an ion exchange method and a reverse osmosis method were mixed, and glass beads were added in a sand mill (Yasukawa Seisakusho). 2 (with a diameter of 1.7 mm and 1.5 times the weight (weight) of the mixture)
Dispersed for hours. After that, the glass beads were removed, other components were added, the mixture was stirred at room temperature for 20 minutes, and then filtered with a 5 μm membrane filter. 80 the obtained filter cake
All of methyl ethyl ketone and a part of water were distilled at ℃ and normal pressure. Furthermore, 1N hydrochloric acid solution was added dropwise with stirring to coagulate the resin layer. Next, suction filtration was carried out while washing this with water to obtain a water-containing pigment cake. While stirring the water-containing cake, a 5% aqueous solution of potassium hydroxide was added dropwise to adjust the liquidity to pH 9 ± 0.5, and ultrapure water was further added so that the solid content became 15%. A pigment dispersion liquid (dispersion liquid Y2) was obtained.

Dispersion M2 As a magenta pigment, C.I. I. Pigment Red 122
100 g, the resin solution used in the case of the dispersion Y2 1
00g, 5% potassium hydroxide aqueous solution 50g, and
Ultrapure water 650 purified by ion exchange method and reverse osmosis method
g were mixed and dispersed in a sand mill (Yasukawa Seisakusho) together with glass beads (diameter 1.7 mm, 1.5 times amount (weight) of the mixture) for 2 hours. After that, the glass beads were removed, other components were added, the mixture was stirred at room temperature for 20 minutes, and then filtered with a 5 μm membrane filter. All of the methyl ethyl ketone and a part of water were distilled from the obtained filter cake at 80 ° C. under normal pressure. Furthermore, 1N hydrochloric acid solution was added dropwise with stirring to coagulate the resin layer. Then,
Suction filtration was performed while washing this with water to obtain a water-containing cake of pigment. While stirring this water-containing cake, a 5% aqueous solution of potassium hydroxide was added dropwise to adjust the liquidity to pH 9 ± 0.5, and ultrapure water was further added so that the solid content became 15%. A pigment dispersion (dispersion M2) was obtained.

Dispersion C2 C.I. I. Pigment Blue 15: 3
100 g, the resin solution used in the case of the dispersion Y2 1
00 g, 5% potassium hydroxide aqueous solution 100 g, and ultrapure water purified by ion exchange method and reverse osmosis method 6
50 g was mixed and dispersed in a sand mill (manufactured by Yasukawa Seisakusho) together with glass beads (diameter 1.7 mm, 1.5 times amount (weight) of the mixture) for 2 hours. After that, the glass beads were removed, other components were added, the mixture was stirred at room temperature for 20 minutes, and then filtered with a 5 μm membrane filter. All of the methyl ethyl ketone and a part of water were distilled from the obtained filter cake at 80 ° C. under normal pressure. Furthermore, 1N hydrochloric acid solution was added dropwise with stirring to coagulate the resin layer. about,
Suction filtration was performed while washing this with water to obtain a water-containing cake of pigment. While stirring the water-containing cake, a 5% aqueous solution of potassium hydroxide was added dropwise to adjust the liquidity to pH 9 ± 0.5, and ultrapure water was added so that the solid content became 15%. A pigment dispersion (dispersion C2) was obtained.

MA100 (trade name, manufactured by Mitsubishi Chemical Co., Ltd.) as dispersion K3 carbon black, 100 g of styrene-acrylic acid type water-soluble resin, Jonkuryl 63 (trade name) (Johnson Polymer Co., Ltd., average molecular weight 12,000, acid value) 21
0, solid content 30%) 250 g, potassium hydroxide 6
g, and 250 g of ultrapure water purified by the ion exchange method and the reverse osmosis method were mixed, and dispersed by a ball mill using zirconia beads for 10 hours. The resulting dispersion stock solution was filtered through a membrane filter (trade name) (manufactured by Japan Millipore Limited) having a pore size of about 8 μm to remove coarse particles, and then diluted with ultrapure water until the pigment concentration reached 15% by weight. A carbon black pigment dispersion liquid (dispersion liquid K3) dispersed with a water-soluble resin was obtained.

Preparation of Ink Composition Preparation of Black Ink Composition According to the composition shown in Table 1, each dispersion described above, solvents and ultrapure water were mixed and stirred for 2 hours. Next, a membrane filter (trade name) with a pore size of about 1.2 μm
The solution was filtered using (manufactured by Japan Millipore Limited) to prepare a black ink composition. The black ink compositions k1 to k5 are ink compositions using a surface-treated black pigment. The black ink composition k6 is a polymer dispersant type black pigment ink composition used in the ink set of the comparative example. In addition, in the above table, Nissan Nonion NS210
(Trade name) is polyoxyethylene nonylphenyl ether, which is available from NOF CORPORATION.

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[Table 1]

Preparation of Chromatic Ink Composition According to the compositions shown in Tables 2 and 3, a polymer dispersant type pigment dispersion, a solvent and ultrapure water were mixed and stirred for 2 hours. Subsequently, the chromatic color ink compositions y1 to y5 and m1 are filtered using a membrane filter (trade name) (manufactured by Nippon Millipore Limited) having a pore size of about 1.2 μm.
m5 and c1-c5 were prepared. A polymer dispersant type pigment ink composition was prepared according to the following formulation.

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[Table 2]

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[Table 3]

Preparation of Ink Set Ink sets 1 to 6 containing black, yellow, magenta, and cyan were prepared. At this time, for the respective colors of black, yellow, magenta, and cyan constituting the ink set, the ink compositions shown in Table 4 were adopted. Ink sets 1 to 5 (Example)
Is a surface-treated black pigment ink composition used as black, and is the ink set 6 (comparative example).
Is a polymer dispersant type black pigment ink composition used as black.

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[Table 4]

Print quality evaluation test Printer EM-900C was used for each ink set.
(Seiko Epson), resolution 720dpi
Then, a full-color chart of 255 gradations was printed as a print image. At this time, the recording paper is Xerox 402.
4 (manufactured by Xerox) was used. The print quality of each obtained print was evaluated. To evaluate the print quality, each print was tested for white spots, color bleed, and color reproducibility, and judged as follows.

Test a: White spot The above-mentioned printed matter was visually and microscopically observed and evaluated according to the following criteria. Microscope BH
Observation was performed at a magnification of 50 times using Z-UMA (manufactured by OLYMPUS). It should be noted that the white spots here refer to a blank portion which remains in a dot shape without being printed in the printed matter by visual observation or microscope observation. Evaluation A: White spots were not observed on the printed matter even by microscopic observation. B: White spots were not observed by visual observation, but white spots were observed by microscopic observation. C: White spots were also observed by visual observation. Is observed

Test b: Color bleed The presence or absence of color bleed in the printed matter was observed visually and by a microscope, and evaluated according to the following criteria. For microscope observation, the microscope BHZ-UMA (OLYMPUS
(Manufactured by the company) was used and observation was performed at a magnification of 50 times. Evaluation A: Color bleed is not observed on the printed matter even by microscopic observation Evaluation B: Color bleed is not observed by visual observation, but color bleed is observed by microscopic observation C: Color bleed is also observed by visual observation Is observed

Test c: Color reproducibility Color reproducibility was evaluated by determining the color reproduction range as follows. First, a color chart consisting of color 384 patches and gray 17 patches is printed for each ink set, and Type Spectroli manufactured by Gretag Macbeth is used.
The color of L ^* , a ^* , and b ^* of the above printed matter was measured using no. The color reproduction range is divided into 10 by the L ^* value in the color space, and each L
^* After obtaining the area value of ^a * ^{b *} space ^{(a *} and ^{b *} values), calculates the ^a * ^{b *} space areas of all ^{L * value,} L ^{* a} * b
^* Obtained by calculating the color space volume (gamut value). The obtained results were evaluated according to the following criteria. Evaluation A: Color reproduction range size is 200,000 or more Evaluation B: Color reproduction range size is 150000 or more 20
Evaluation C of less than 0000: The size of the color reproduction range is less than 150,000.

The results are shown in Table 5.

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[Table 5]

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C056 EA04 FC02                 2H086 BA02 BA52 BA55 BA59                 4J039 AB07 AD03 AD06 AD08 AD09                       AD10 AD14 BC07 BC09 BC13                       BC34 BC39 BC60 BE01 BE12                       BE22 CA06 CA07 EA15 EA16                       EA17 EA19 GA24

Claims (16)

[Claims] 1. An ink set comprising a black ink composition and at least one chromatic color ink composition, wherein the black ink composition is dispersed and / or dissolved in water without a dispersant. A possible surface-treated pigment and at least water as a main solvent, and the chromatic ink composition contains at least a pigment, a polymer dispersant for dispersing the pigment, and water as a main solvent. An ink set characterized by consisting of 2. The black ink composition and the chromatic ink composition both further contain a nonionic surfactant and a water-soluble organic solvent as a penetrant at the same time. Ink set. 3. The water-soluble organic solvent is glycol mono-n.
An ink set according to claim 2, which is butyl ether. 4. The ink set according to claim 1, wherein the black ink composition and / or the chromatic color ink composition further comprises a nonionic surfactant. 5. The ink set according to claim 2, wherein the nonionic surfactant is an acetylene glycol-based surfactant. 6. The ink set according to claim 1, wherein the black ink composition and / or the chromatic ink composition further comprises a 1,2-alkanediol. 7. The 1,2-alkanediol is selected from the group consisting of 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and mixtures thereof. The ink set according to claim 6, which is formed. 8. The ink according to claim 1, wherein the chromatic color ink composition is composed of at least two or more chromatic color ink compositions capable of printing an achromatic color when combined with each other. set. 9. The ink set according to claim 1, wherein the chromatic ink composition comprises a cyan ink composition, a magenta ink composition, and a yellow ink composition. 10. The chromatic ink composition comprises two cyan ink compositions having different color densities, two magenta ink compositions having different color densities, and a yellow ink composition. 9. The ink set according to any one of items 8 to 8. 11. The black ink composition comprises a pigment 1
The ink set according to any one of claims 1 to 10, which comprises -30% by weight. 12. The chromatic color ink composition comprises a pigment of 0.
The ink set according to any one of claims 1 to 11, which comprises 5 to 10% by weight. 13. An ink jet recording method,
The ink set according to any one of claims 1 to 12. 14. An ink jet recording method for ejecting droplets of an ink composition and adhering the droplets to a recording medium to perform printing, wherein the ink composition is a black ink composition and a black ink composition. Using at least two or more chromatic color ink compositions capable of printing color, the black ink composition is a surface-treated pigment that can be dispersed and / or dissolved in water without a dispersant, and water as a main solvent. Wherein the chromatic ink composition comprises at least a pigment, a polymer dispersant for dispersing the pigment, and water as a main solvent, and When ink dots printed by combining chromatic color ink compositions are achromatic, a black ink composition is ejected instead of the combination of the chromatic color ink compositions. An ink jet recording method, characterized in that the dots are printed by printing. 15. The inkjet recording method according to claim 14, wherein the ink composition of the ink set according to any one of claims 1 to 13 is used as the ink composition. 16. A recorded matter recorded by the method according to claim 14.