JPH1053740A - Recording ink and method for recording therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a recording ink improved in hue and color reproducibility and giving images reduced in blotting and improved in water resistance and light resistance by mixing a specified water-dispersible or -soluble colorant with a specified dispersant, water and a water-soluble organic solvent. SOLUTION: A water-dispersible or -soluble colorant comprising a quinacridone pigment represented by formula I (wherein R1 and R2 are each a halogen or H), a phthalocyanine pigment represented by formula II (wherein M is copper, iron, nickel or H; X is H or a halogen; and p is 0-8) and a polymeric dye having an average molecular weight of 500-150,000 and obtained by forming a salt from a sulfo-containing polymer and a basic dye represented by formula III or IV is mixed with a dispersant comprising a polymer having hydrophilic moiety and a hydrophobic moiety and/or a surfactant having a 6C or higher alkyl, a hydrophilic organic solvent, water and optionally a nonionic surfactant having a polyoxyalkylene group and a urea (derivative) to obtain a recording ink.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording ink suitable for use in ink-jet recording, water-based writing utensils, recorders, pen plotters, etc., and more particularly to a recording ink suitable for ink-jet recording, and more particularly a so-called ordinary ink. The present invention relates to an ink jet recording ink which exhibits particularly excellent properties for forming a color image on paper. The present invention also relates to a recording method using the recording ink.

[0002]

2. Description of the Related Art In recent years, inkjet printers have become popular due to their advantages such as low noise and low running cost, and power printers capable of printing on plain paper have also been put on the market. In such an ink jet printer, it is necessary to satisfy color reproducibility of a color image, water and light resistance of an image, drying of an image, prevention of image bleeding, and ejection reliability. It is difficult to satisfy everything.

When a color image is formed by an ink jet printer, even if a clear image is formed in a single-color printing portion of yellow, magenta, and cyan, the image is blurred in a portion where two colors of red, green, and blue overlap. This is disadvantageous in that sharpness easily occurs and the sharpness of an image is reduced. In particular, when a recorded image is dried by inkjet recording without using a fixing device, the drying property of the recorded image is increased by increasing the permeability of the recording liquid to the recording paper as disclosed in JP-A-55-29546. Has the drawback that the bleeding of the image becomes remarkable depending on the recording paper used, and the sharpness of the image deteriorates. In addition, Tokiko Sho 60-
Japanese Patent No. 23793 discloses that by adding a dialkyl sulfosuccinate as a surfactant to an ink for ink jet recording, the drying property of a recorded image by ink jet recording is improved and the decrease in sharpness of the image is reduced. However, depending on the type of recording paper used, there is a problem that the pixel diameter is significantly different, the image density is also significantly reduced, and the sharpness of the image is significantly reduced.When the recording ink is alkaline, the surfactant is decomposed and the recording ink is degraded. During storage, there is a disadvantage that the effect of the surfactant is lost, a precipitate is formed in the recording ink, nozzle clogging occurs in an ink jet printer, and the ejection reliability is reduced.

Furthermore, Japanese Patent Application Laid-Open No. 56-57862 discloses that the drying property of an image recorded by ink jet recording is improved by adding a strong basic substance to the ink for ink jet recording. However, when an image is formed on a rosin-sized acidic paper, the effect of improving the drying property is obtained, but the effect of improving the drying property is not seen in the recording paper using an alkyl ketene dimer or alkenyl sulfosuccinic acid as a sizing agent, Further, even with acidic paper, there is a disadvantage that the effect of improving the drying property is not seen in the two-color superposed portion in the recorded image. Also, Japanese Patent Application Laid-Open No. 1-20
No. 3483 discloses that a recording ink contains a polyhydric alcohol derivative and pectin to prevent bleeding of a recorded image by pectin as a thickener, but pectin has a hydroxyl group as a hydrophilic group. However, since it is a nonionic compound, there is a disadvantage that the ejection reliability after printing is stopped is lacking.

On the other hand, dyes used in ink jet recording inks have been improved in order to achieve both color reproducibility of color images on plain paper and light fastness and water fastness. It is difficult to obtain a dye having improved water resistance and high discharge reliability. Various attempts have been made to use pigments in order to obtain water resistance and light resistance of a recorded image, but because of the problem of color tone, they are currently used except for large plotters that require particularly light resistance. Absent. Further, when a pigment is used, there is a problem that clogging occurs in an ink jet printer or the like corresponding to an increase in resolution of a recorded image, resulting in a lack of ejection reliability.

Therefore, it has been proposed to use a mixture of a pigment and a dye in order to improve color tone and color reproducibility of a color image, and to improve light fastness, water fastness and ejection reliability of the image. JP-A-60-45668 and JP-A-6-10
No. 0812, etc., the former does not have sufficient light fastness of the dye, the ink does not necessarily have sufficient penetrability and color development into plain paper, and the latter has lightfastness as compared with the former. Sufficient, but insufficient in color development, and in particular, there is a problem such as dull blue color. Further, recording inks using a polymer dye having a sulfonic acid group formed with a basic dye are disclosed in JP-A-60-38481 and JP-A-60-38482. However, they have insufficient light resistance, and are liable to cause clogging in an ink jet printer or the like, and have a disadvantage of lacking ejection reliability. As described above, conventionally, a recording ink capable of forming a clear image having excellent color tone, good color reproducibility, little image bleeding, and sufficient water resistance and light resistance, particularly ink jet recording It was difficult to obtain a recording ink having high ejection reliability in the above.

[0007]

Accordingly, a first object of the present invention is to solve such problems and to form a clear image having excellent color tone, good color reproducibility, and little image bleeding. Another object of the present invention is to provide a recording ink excellent in water resistance and light resistance of an image. In particular, it is an object of the present invention to provide a recording ink that is excellent in color reproducibility of secondary colors such as blue, green, and green and that can form an image having excellent transparency on a transparent sheet for an overhead projector. A second object of the present invention is to provide a recording ink having high ejection stability in ink jet recording, particularly having excellent dispersion stability of a colorant and excellent storage stability, even after long-term storage or after printing suspension. To provide. A third object of the present invention is to provide a recording ink capable of forming a clear image with high permeability of the recording ink into plain paper, excellent drying properties of the formed image, and prevention of image bleeding. Is to provide. A fourth object of the present invention is to provide a magenta recording ink and a cyan recording ink excellent in color reproducibility. A fifth object of the present invention is to provide an ink jet recording method capable of forming an image having excellent water resistance and light resistance, good color reproducibility and excellent clarity at a high resolution.

[0008]

The object of the present invention is to provide a colorant that is dispersed or dissolved in water, a recording ink containing water and a water-soluble organic solvent as main components, and a colorant represented by the following general formula (1): And a phthalocyanine pigment represented by the following general formula (2) and at least one phthalocyanine pigment represented by the following general formula (2): A recording ink comprising a polymer dye simultaneously and a polymer compound having a hydrophilic portion and a hydrophobic portion and / or a surfactant having an alkyl group having 6 or more carbon atoms as a dispersant. Achieved by

Embedded image (In the formula, R ₁ and R ₂ represent an alkyl group, a halogen atom or a hydrogen atom.)

Embedded image (Wherein, M represents a copper, iron, nickel or hydrogen atom,
X represents a hydrogen atom or a halogen atom. p is from 0 to 8
Represents an integer. )

According to the present invention, as a coloring agent, at least one of a quinacridone pigment represented by the following general formula (1) and a phthalocyanine pigment represented by the following general formula (2), and a polymer having a sulfonic acid group By using a high molecular dye having an average molecular weight of 5,000 to 150,000 obtained by salting a basic dye into a compound to form an image having excellent color tone, good color reproducibility, and excellent water resistance and light resistance. Can be. Further, the recording ink containing the coloring agent is colored by adding a polymer compound having a hydrophilic portion and a hydrophobic portion and / or a surfactant having an alkyl group having 6 or more carbon atoms as a dispersant. It is possible to obtain a recording ink having excellent storage stability by improving the dispersion stability of the agent, and it is possible to perform inkjet recording with high ejection reliability even after long-term storage or after printing suspension. Further, by incorporating a polymer compound having a hydrophilic portion and a hydrophobic portion and / or a surfactant having an alkyl group having 6 or more carbon atoms as a dispersant, the permeability of the recording ink into plain paper is increased. As a result, it is possible to improve the drying property of the formed image and to form a clear image in which blurring of the image is prevented.

Specific examples of the quinacridone pigment represented by the general formula (1) and the phthalocyanine pigment represented by the general formula (2) include those shown in Tables 1 and 2 below. However, the present invention is not limited to this.

[0011]

[Table 1]

[0012]

[Table 2]

The polymer dye having an average molecular weight of 5,000 to 150,000 obtained by salting a basic dye into a polymer compound having a sulfonic acid group is particularly preferable for a polymer compound having a sulfonic acid group and a hydroxyl group. A polymer dye obtained by salting a basic dye represented by the chemical formula (3) or (4) is preferable.

Embedded image

More specifically, a copolymer of p-styrene sulfonic acid and hydroxyalkyl methacrylate or hydroxyalkyl acrylate is used as the polymer compound having a sulfonic acid group, and the copolymer represented by the above formula (3)
Alternatively, a polymer dye obtained by salting a basic dye represented by the formula (4) is preferable. In particular, a copolymer of p-styrenesulfonic acid and hydroxyethyl methacrylate or hydroxyethyl acrylate is used. Polymer dyes obtained by salting the basic dyes represented by 3) or (4) are preferred. By using a copolymer of p-styrenesulfonic acid and hydroxyalkyl methacrylate or hydroxyalkyl acrylate as the polymer compound having a sulfonic acid group, a recording ink having particularly excellent dispersion stability can be obtained.

A specific example of the polymer dye is represented by the following chemical formula (3-
P) or (4-P), but is not limited thereto.

[0016]

Embedded image

Such a high molecular dye is disclosed in JP-A-60-3
No. 85482 and the like, and can be produced using a reverse osmosis membrane or an ion exchange resin to obtain NaCl, Na ₂ SO ₄ , CaC
It is preferable to use one from which inorganic salt impurities such as O ₃ have been removed. By removing the inorganic salt impurities, clogging of the head in the ink jet printer and clogging of the filter in the printer can be prevented, and the discharge reliability can be improved.

A polymer dye obtained by forming a basic dye into a polymer compound having a sulfonic acid group is converted into a quinacridone pigment represented by the above formula (1) or a phthalocyanine represented by the above formula (2) By using the pigment together with the pigment, it is possible to obtain a recording ink having improved chroma, excellent color tone, good color reproducibility, and excellent image water fastness and light fastness. In particular, in the recording ink of the present invention, a quinacridone-based pigment represented by the above general formula (1) and a basic dye represented by the above chemical formula (3) are formed on a polymer compound having a sulfonic acid group as a coloring agent. By using a salted polymer dye, for example, a polymer dye represented by the above chemical formula (3-P), a magenta color excellent in color tone, excellent in color reproducibility, and excellent in water fastness and light fastness of an image. Can be obtained. In addition, a polymer dye obtained by salting a phthalocyanine pigment represented by the general formula (2) and a polymer compound having a sulfonic acid group with a basic dye represented by the chemical formula (4) as a coloring agent, for example, By using the polymer dye represented by the chemical formula (4-P), it is possible to obtain a cyan recording ink having excellent color tone, excellent color reproducibility, and excellent image water resistance and light resistance. .

In the present invention, other pigments may be used in combination with the quinacridone pigment represented by the general formula (1) or the phthalocyanine pigment represented by the general formula (2) as a coloring agent. Examples of such pigments include azo-based, phthalocyanine-based, anthraquinone-based, dioxazine-based, indigo-based, thioindigo-based, perylene-based, isoindolenone-based, aniline black, azomethine-based, rhodamine B-rake pigments, and carbon black. Pigment or iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow,
Inorganic pigments such as navy blue, cadmium red, chrome yellow, metal powder and the like.

The particle diameter of the quinacridone pigment represented by the general formula (1), the phthalocyanine pigment represented by the general formula (2) and other pigments is 0.01 μm to 0.1 μm.
μm is preferred, and when it is smaller than 0.01 μm, the hiding power is reduced and the image density is reduced, and the light resistance is reduced and the light resistance of the image when used with a polymer dye is reduced by a conventional dye-based recording ink. This is equivalent to the light fastness of the image, and the effect of improving the light fastness of the image cannot be obtained. On the other hand, when the thickness exceeds 0.1 μm, clogging of a head in an ink jet printer and clogging of a filter in the printer occur, thereby lowering ejection reliability. Further, by using titanium oxide having a particle diameter of 0.1 μm or less together with the quinacridone pigment represented by the general formula (1) or the phthalocyanine pigment represented by the general formula (2), the light fastness of the image is improved. It can be further improved.

Next, the dispersant used in the present invention will be described. As a pigment dispersant comprising a polymer compound having a hydrophilic part and a hydrophobic part, as a hydrophilic polymer, in the natural system, gum arabic, gum tragan, guar gum, karaya gum, low-strength bean gum, arabinogalactone, pectin, quince In plant macromolecules such as seed starch, alginic acid, carrageenan, algae such as agar, animal macromolecules such as gelatin, casein, albumin and collagen, microbial macromolecules such as xanthen gum and dextran, and semi-synthetic systems , Methylcellulose,
Ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, fibrous polymers such as carboxymethyl cellulose, sodium starch glycolate, starch polymers such as sodium starch phosphate, sodium alginate, seaweed polymers such as propylene glycol alginate, In pure synthesis,
Polyvinyl alcohol, polyvinylpyrrolidone, vinyl polymers such as polyvinyl methyl ether, non-crosslinked polyacrylamide, polyacrylic acid and alkali metal salts thereof, acrylic resins such as water-soluble styrene acrylic resin,
Water-soluble styrene maleate resin, water-soluble vinyl naphthalene acrylic resin, water-soluble vinyl naphthalene maleate resin, polyvinyl pyrrolidone, polyvinyl alcohol, β
-Alkali metal salt of naphthalenesulfonic acid formalin condensate, a high molecular compound having a salt of a cationic functional group such as a quaternary ammonium or an amino group in a side chain and the like, and a natural high molecular compound such as shellac can also be used. Can be used.

As the surfactant having an alkyl group having 6 or more carbon atoms, a nonionic surfactant having a polyoxyalkylene group is preferable. In particular, a polyoxyethylene alkyl represented by the following general formula (5) is preferable. Phenyl ether, an acetylene glycol-based surfactant represented by the following general formula (6), a polyoxyethylene alkyl ether represented by the following general formula (7), or a polyoxyethylene poly represented by the following general formula (8) Oxypropylene alkyl ethers are preferred. By using these nonionic surfactants, the permeability of the recording ink to recording paper such as plain paper is increased, the drying property of the image is improved, and the image with excellent clarity is prevented by preventing image bleeding. Can be formed.

Embedded image (In the formula, R ₃ represents an optionally branched carbon chain having 6 to 14 carbon atoms, and k represents an integer of 5 to 20.)

Embedded image (In the formula, m and n represent an integer of 0 to 20.)

Embedded image (In the formula, R ₄ represents an optionally branched carbon chain having 6 to 14 carbon atoms, and n represents an integer of 5 to 20.)

Embedded image (In the formula, R ₅ represents a carbon chain having 6 to 14 carbon atoms which may be branched, and m and n each represent an integer of 0 to 20. However, both m and n do not become 0.)

Examples of the carbon chain of R ₃ , R ₄ and R ₅ include an alkyl group and an alkenyl group. In particular, by using these surfactants and setting the surface tension of the recording ink to 50 mN / m or less, the wettability between the recording ink and the surface of recording paper such as plain paper can be further improved. It is possible to improve the dryness of a recorded image by increasing the permeability of the recording ink into the paper, and prevent blurring of the image, thereby forming an image with excellent clarity.

The surface tension is an index indicating the permeability of the recording ink into the recording paper.
It shows a dynamic surface tension in a short time of less than a second and is different from the static surface tension measured in the saturation time. As a measuring method, any method can be used as long as it can measure a dynamic surface tension of 1 second or less by a conventionally known method described in JP-A-63-31237.
The value is shown by a value measured using an ilhelmy type hanging plate surface tensiometer. The value of the surface tension is preferably 50 mN / m or less, and if it is particularly 40 mN / m or less, further excellent image drying properties can be obtained.

When the pigment and a high molecular dye prepared by salting a basic dye are used as a coloring agent, the nonionic surfactant having a polyoxyalkylene group is colored by solubilization with a polyoxyethylene chain. It is possible to obtain an ink for recording that has improved storage stability and excellent storage stability of the agent, and performs inkjet recording with high ejection reliability and without image deterioration even after the recording ink is stored for a long time. Can be. Further, when urea or a urea derivative such as hydroxyethyl urea or dihydroxyethyl urea is used together with the above nonionic surfactant, the interaction between the polymer dye and the nonionic surfactant is weakened, By alleviating dye association,
It is possible to improve the permeability of the recording ink to the recording paper, and further improve the long-term storability of the recording ink and the ejection reliability in ink jet recording. The amount of the urea or urea derivative added is 0.1% of the recording ink.
~ 5% by weight is preferred. If the amount is less than 0.1% by weight, there is no effect. If the amount exceeds 5% by weight, the viscosity change at the time of evaporation of water is affected, and the discharge reliability after printing pause may be reduced.

The recording ink of the present invention is one in which the above-mentioned components are dispersed or dissolved in water. However, in order to prevent drying of the recording ink during storage, or to disperse the coloring agent. A water-soluble organic solvent is added to the recording ink of the invention for the purpose of improving the dissolution stability and the like.

Examples of such a water-soluble organic solvent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,5-pentanediol, and 1,6.
Hexanediol, glycerol, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,
2,3-butanetriol, polyhydric alcohols such as petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether,
Polyhydric alcohol alkyl ethers such as propylene glycol monoethyl ether and the like, polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone , 2-pyrrolidone, 1,3-dimethylimidazolidinone, nitrogen-containing heterocyclic compounds such as ε-caprolactam,
Amides such as formamide, N-methylformamide, N, N-dimethylformamide, amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine, and sulfur-containing such as dimethylsulfoxide, sulfolane, thiodiethanol and the like. Compounds, propylene carbonate, ethylene carbonate, γ-butyrolactone, etc. can be exemplified,
These water-soluble organic solvents can be used alone or in combination of two or more.

Among these, particularly preferred water-soluble organic solvents are diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, and triethylene glycol.
Glycerol, 1,2,6-hexanetriol,
1,2,4-butanetriol, petriol, 1,5
-Pentanediol, N-methyl-2-pyrrolidone, N
-Hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and the like. The use of these water-soluble organic solvents improves the dispersion stability and dissolution stability of the colorant and evaporates water. Can prevent drying of the recording ink, and can perform ink jet recording with excellent ejection reliability even after the recording ink is stored for a long period of time or even when printing is paused for a long period of time. it can. In particular, when a pyrrolidone derivative such as N-hydroxyethyl-2-pyrrolidone is added to the recording ink, the dispersion stability of the colorant, especially the pigment, is improved, and the affinity for the recording paper is increased. Can be. As a result, even after the recording ink is stored for a long period of time, it is possible to perform ink jet recording with higher ejection reliability in ink jet recording, and it has a high density on the recording paper and a clear dot excellent in dot uniformity. An image can be formed.

The recording ink of the present invention has the general formulas (5), (6) and (7) for the purpose of adjusting the surface tension.
Or other than the surfactant represented by (8), diethylene glycol monophenyl ether, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, tetraethylene glycol chlorophenyl ether Alkyl or aryl ethers of polyhydric alcohols such as polyoxyethylene polyoxypropylene block copolymers, fluorine-based surfactants, or lower alcohols such as ethanol and 2-propanol. Monobutyl ether is preferred.

As the coloring material of the present invention, in addition to the above-mentioned pigments and high molecular dyes, other dyes can be mixed and used as required. As such a dye, a water-soluble dye classified into an acid dye, a direct dye, a basic dye, a reactive dye, and an edible dye in a color index and having excellent water resistance and light resistance is used. These are added within a range in which effects such as color reproducibility, water resistance, and light resistance are not excluded.

Specific examples of these dyes include acid dyes and food dyes such as C.I. I. Acid Yellow 1
7, 23, 42, 44, 79, 142, C.I. I. Acid Red 1,8,13,14,18,26,27,3
5,37,42,52,82,87,89,92,9
7, 106, 111, 114, 115, 134, 18
6,249,254,289, C.I. I. Acid Blue 9, 29, 45, 92, 249, C.I. I. Acid Black 1, 2, 7, 24, 26, 94, C.I. I. Food yellow 3, 4, C.I. I. Food Red 7, 9, 14,
C. I. As food black 1,2, direct dye,
C. I. Direct Yellow 1,12,24,26,3
3,44,50,86,120,132,142,14
4, C.I. I. Direct Red 1,4,9,13,1
7, 20, 28, 31, 39, 80, 81, 83, 8
9,225,227, C.I. I. Direct orange 2
6, 29, 62, 102, C.I. I. Direct Blue 1,2,6,15,22,25,71,76,79,8
6,87,90,98,163,165,199,20
2, C.I. I. Direct Black 19, 22, 32, 3
8, 51, 56, 71, 74, 75, 77, 154, 1
68,171; basic dyes such as C.I. I. Basic Yellow 1, 2, 11, 13, 14, 15, 19, 2
1,23,24,25,28,29,32,36,4
0, 41, 45, 49 • 51, 53, 63, 64, 6
5, 67, 70, 73, 77, 87, 91, C.I. I. Basic Red 2,12,13,14,15,18,2
2,23,24,27,29,35,36,38,3
9, 46, 49, 51, 52, 54, 59, 68, 6
9, 70, 73, 78, 82, 102, 104, 10
9, 112, C.I. I. Basic Blue 1,3,5
7, 9, 21, 22, 26, 35, 41, 45, 47,
54, 62, 65, 66, 67, 69, 75, 77, 7
8, 89.92, 93, 105, 117, 120, 12
2,124,129,137,141,147,15
5, C.I. I. Basic Black 2, 8 and reactive dyes include C.I. I. Reactive Black 3,4,7,1
1, 12, 17, C.I. I. Reactive Yellow 1,
5,11,13,14,20,21,22,25,4
0, 47, 51, 55, 65, 67, C.I. I. Reactive Red 1,14,17,25,26,32,37,
44, 46, 55, 60, 66, 74, 79, 96, 9
7, C.I. I. Reactive Blue 1,2,7,14,1
5,23,32,35,38,41,63,80,95
And the like, and particularly preferred are acid dyes and direct dyes.

Further, the recording ink of the present invention may contain additives known in the art, such as a preservative / antifungal agent, a rust inhibitor,
An H adjuster, a water-soluble ultraviolet absorber or a water-soluble infrared absorber can be added.

As preservatives and fungicides, sodium dehydroacetate, sodium sorbate, 2-pyridinethiol-1
Sodium oxide, sodium benzoate, sodium pentachlorophenol, and the like,
Acid sulphite, sodium thiosulphate,
Ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite, and the like can be used.

As the pH adjuster, any substance can be used as long as it can adjust the pH to 6 or more without adversely affecting the prepared recording ink. Specific examples thereof include: Amines such as diethanolamine and triethanolamine; hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide;
Quaternary ammonium hydroxides such as ammonium hydroxide,
Quaternary phosphonium hydroxide or lithium carbonate,
Examples thereof include carbonates of alkali metals such as sodium carbonate and potassium carbonate. As the chelating reagent, for example, sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate and the like can be used.

In order to perform ink-jet recording using the recording ink of the present invention, the recording ink is discharged from a fine discharge port having a diameter of, for example, 20 to 60 μm by thermal energy or mechanical energy, and weighs 10 ng to 160 ng.
The color reproducibility is obtained by forming an image on a recording paper having a Stigget sizing degree of 3 seconds or more, especially a so-called plain paper having a Stechig sizing degree of 3 seconds or more, by flying at a speed of 5 to 20 m / s as a liquid droplet of , And an image with excellent sharpness can be formed at high resolution. The amount of ink adhered on the recording paper surface at this time is preferably from 2 g / m ² to 25 g / m ^2. According to this amount of ink, the recording paper may change due to water absorption such as curling or waving. Not
Good image density can be secured. In particular, by Stockigt sizing degree allowed to the recording ink in the recording paper over three seconds from 2.0g / m ² 20g / m ² adhesion, resolution 10 dots / mm × 10 dots / mm or more high-resolution images Can be formed. Furthermore, by using the recording ink of the present invention, an image having excellent color reproducibility and transparency can be formed on a transparent sheet for an overhead projector (OHP).

[0036]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 First, the pigment (1-1) shown in Table 1 was dispersed by an ultrasonic homogenizer in the presence of a dispersant to reduce the particle diameter to 0.1.
Using a dispersion having a particle size of 1 μm or less, the composition having the following formulation was stirred and dissolved, and the pH was adjusted to 7.5 with a 10% aqueous solution of lithium hydroxide. The resultant was filtered through a 0.45 μm Teflon filter. A recording ink was obtained. Pigment of (1-1) shown in Table 1 2% by weight Polymer dye of the formula (3-P) 4% by weight Styrene acrylic acid polymer 0.4% by weight Glycerol 5% by weight N-hydroxyethylpyrrolidone 10 % By weight Surfactant of the general formula (5) (R ₃ = C ₉ H ₁₉ , k = 18) 2% by weight Surfactant of the general formula (5) (R ₃ = C ₉ H ₁₉ , k = 10) 1 Wt% sodium dehydroacetate 0.2 wt% ion exchange water

Example 2 A recording ink was obtained in the same manner as in Example 1 except that the following composition was used and the pH was adjusted to 6.8 with sodium hydroxide. Pigment of (2-1) shown in Table 1 above 1.2% by weight Polymer dye of the above formula (4-P) 4% by weight 1,2,6-hexanetriol 4% by weight 1,5-pentanediol 8 % By weight N-methyl-2-pyrrolidone 10% by weight Surfactant of general formula (6) (m, n = 20) 1.2% by weight Surfactant of general formula (6) (m, n = 10) 1 Weight% sodium alginate 0.05 weight% urea 5 weight% 2-pyridinethiol-1-oxide sodium 0.2 weight% ion exchange water

Example 3 A recording ink was obtained in the same manner as in Example 1 except that the following composition was used and the pH was adjusted to 8.5 with lithium hydroxide. Pigment of (1-2) shown in Table 1 1% by weight Polymer dye of the formula (3-P) 0.5% by weight Titanium oxide (particle diameter 0.1 μm) 0.3% by weight Diethylene glycol 5% by weight glycerol 5 wt% n-hydroxyethyl pyrrolidone 10 wt% styrene surfactant acrylic acid polymer 0.5% by weight formula _{(7) (R 4 = C} 9 H 19, n = 12) 2 wt% sodium dehydroacetate 0.2% by weight ion exchange water

Example 4 A recording ink was obtained in the same manner as in Example 1 except that the following composition was used and the pH was adjusted to 9.5 with lithium hydroxide. Pigment of (2-3) shown in Table 1 above 1.0% by weight Polymer dye of the above formula (4-P) 2.2% by weight Ethylene glycol 5% by weight Glycerol 2% by weight 1,5-pentanediol 8 wt% 2-pyrrolidone 2 wt% formula surfactant _{(8) (R 5 = C} 6 H 13, m, n = 20) 0.8 wt% urea 5 wt% sodium benzoate 0.2% ion Exchange water level

Example 5 A recording ink was obtained in the same manner as in Example 1 except that the following composition was used and the pH was adjusted to 7.8 with sodium hydroxide. Pigment of (2-1) shown in Table 1 above 0.8% by weight Pigment of (2-4) shown in Table 2 above 0.2% by weight Polymer dye of chemical formula (4-P) 3.5 wt% triethylene glycol 5 wt% petriol 10 wt% n-methyl-2-pyrrolidone 5 wt% formula surfactant 2% by weight of (7) _{[R 4: (C 6 H 13} ) 2 CH-, n = 12] hydroxyethyl urea 5% by weight 2-pyridinethiol-1-oxide sodium 0.2% by weight Deionized water

Comparative Example 1 In Example 1, C.I. was replaced with the pigment (1-1) and the high molecular dye represented by the chemical formula (3-P) shown in Table 1 above. I. A recording ink was obtained in the same manner as in Example 1 except that Acid Red 52 was used.

Comparative Example 2 In Example 2, C.I. was replaced with the pigment (2-1) and the polymer dye represented by the chemical formula (4-P) shown in Table 1 above. I. A recording ink was obtained in the same manner as in Example 2 except that Acid Blue 249 was used.

Comparative Example 3 The procedure of Example 3 was repeated, except that the polymer dye of the formula (3-P) was replaced by C.I. I. A recording ink was obtained in the same manner as in Example 3 except that Acid Red 35 was used.

Comparative Example 4 In Example 4, C.I. was replaced with the pigment (2-3) and the polymer dye represented by the chemical formula (4-P) shown in Table 1 above. I. A recording ink was obtained in the same manner as in Example 4 except that Acid Blue 9 was used.

Comparative Example 5 A recording ink was obtained in the same manner as in Example 5 except that the surfactant represented by the general formula (7) was omitted.

Next, the above Examples 1 to 5 and Comparative Examples 1 to 5
The following test was performed on the recording ink obtained by the method described above. Table 3 shows the results. 1) Clearness of image Nozzle diameter of thermal ink jet system 45 μm, 30
Nozzle diameter 33 using inkjet printer having 0 dpi nozzle and laminated PZT for pressurizing liquid chamber flow path
Printing is performed on three types of printing paper, commercially available recycled paper, woodfree paper, and bond paper, using an inkjet printer having a nozzle of 128 μm and 128 dpi, and the printed image is blurred at the boundary of a two-color overlapped portion, image blur, color tone, and density. Was visually judged comprehensively, and the sharpness of the image was evaluated. Table 3
In the above, a circle indicates a case where the characteristics of a printed image are satisfied with any of the three types of printing papers, and a triangle indicates a case where the characteristics of the printed image are satisfied with at least one type of printing paper.
The marks indicate the cases where none of the three types of printing paper is satisfied. Further, printing was performed on a PET film having a layer mainly composed of PVA on the surface using the recording inks of Examples and Comparative Examples, and P
The ET film was projected by an overhead projector to evaluate the color development. In Table 3, the mark が indicates that the transparency is high and the color development of the two-color overlapping portion and the single-color portion is good, and the mark Δ indicates that the coloring of the single-color portion is good but the coloring of the two-color overlapping portion is slightly dull. , And the crosses indicate that the color development in the single color portion is also poor. 2) Image Water Resistance The printed image sample was immersed in water at 30 ° C. for 1 minute, and the change in image density before and after the treatment was measured with a Macbeth densitometer, and the water resistance (fading rate%) was determined by the following equation. In Table 3,
A mark indicates a case where the water resistance (fading rate%) is less than 10%, a mark indicates a case where the water resistance is 10% or more and less than 30%, and a mark indicates a case where the water resistance is less than 10%. Shows the case. Fading rate (%) = [1- (image density after processing / image density before processing)] × 100 3) Light fastness of image The printed image sample was irradiated with a xenon feed meter at a black panel temperature of 63 ° C. for 3 hours. The change in image density before and after the processing was measured with a Macbeth densitometer, and the light fastness (fading rate%) was determined by the following equation. In Table 3, a circle indicates a case where the light resistance (fading rate%) is less than 5%, a triangle indicates a case where the light resistance is 5% or more and less than 30%, and a cross indicates a case where the light fastness (% of fading rate) is less than 5%. % Is shown. Fading rate (%) = [1− (image density after processing / image density before processing)] × 100 4) Dryness of image The filter paper is pressed against the image after printing under a certain condition, and the recording ink is transferred to the filter paper. The time until disappearance was measured. In Table 3, the case where all of the three types of printing paper were dried within 10 seconds was indicated by a circle, and the case where a longer time was required was indicated by a cross. 5) Storage stability Put each recording ink in a polyethylene container,
It was stored for 3 months under the conditions of 5 ° C, 20 ° C, and 70 ° C, and the surface tension, viscosity, and the presence or absence of precipitates after storage were examined. In Table 3, a circle indicates that there was no change in physical properties and the like, a triangle indicates that there was no precipitation but a large change in physical properties, and a cross indicates that precipitation was observed. 6) Reliability at the time of printing suspension PZ having a nozzle diameter of 30 μm and a nozzle of 128 dpi
Using an inkjet printer equipped with a head driven by T, check how much the printing direction can be recovered even if printing is paused without capping, cleaning, etc. during operation. Alternatively, the reliability was evaluated based on the change in the weight of the discharged droplet. In Table 3, the case where there was no problem with printing pause of 600 seconds was evaluated as ○.
Indicated by a mark △, when the change in the droplet weight was small and the shift in the jetting direction was small after printing pause for 600 seconds, and marked X when marked clogging occurred when printing was stopped within 600 seconds.

[0048]

[Table 3]

As is evident from Table 3, when the recording inks obtained in Examples were used, the images were excellent in color tone, good in color reproducibility, free of bleeding and high in density, and provided clear images. An image excellent in water fastness and light fastness can be obtained by using any printing paper, and the image is also excellent in drying property. Furthermore, the recording inks obtained in the examples have excellent storage stability, and can perform inkjet recording with high ejection reliability even after long-term storage or even after printing is stopped.

On the other hand, the recording inks obtained in the comparative examples did not satisfy any of these. That is, the recording ink obtained in Comparative Example 1 is inferior in image clarity due to occurrence of bleeding, and the water resistance and light resistance of the image are poor. In the recording ink obtained in Comparative Example 2, the image clarity is low. And the water resistance of the image was poor, and the storage stability of the recording ink was poor. The recording ink obtained in Comparative Example 3 was inferior in image clarity, poor in water fastness and light fastness of the image, and the recording ink obtained in Comparative Example 4 was inferior in image clarity and water fastness in the image. In addition, the light resistance was poor, and the storage stability of the recording ink was poor. In addition, the recording ink obtained in Comparative Example 5 had poor storage stability and poor ejection reliability. Furthermore, when the recording ink obtained in the example was used, the OHP suitability was good, but when the recording ink obtained in the comparative example was used, the OHP suitability was poor. Was.

[0051]

According to the present invention, it is possible to form a clear image which is excellent in color tone, has good color reproducibility, has little image bleeding, and has excellent water fastness and light fastness of the image. be able to. In particular, it is possible to obtain a recording ink that is excellent in color reproducibility of secondary colors such as blue, green, and red and that can form an image having excellent transparency on a transparent sheet for an overhead projector. Further, according to the present invention, particularly, the dispersion stability of the colorant is excellent, the storage stability is excellent, even after long-term storage or after printing is stopped, a recording ink having high ejection reliability in inkjet recording. Obtainable. Further, according to the present invention, there is provided a recording ink capable of forming a clear image in which the recording ink has high permeability to plain paper, has excellent drying properties of the formed image, and prevents image bleeding. Obtainable. Further, according to the present invention, a magenta recording ink and a cyan recording ink excellent in color reproducibility can be obtained. Furthermore, by the inkjet recording method using the recording ink of the present invention,
An image excellent in water resistance and light fastness, excellent in color reproducibility and excellent in sharpness can be formed with high resolution.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Akiko Konishi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hirotaka Mochizuki 1-3-6 Nakamagome, Ota-ku, Tokyo Share Inside Ricoh Company (72) Inventor Masayuki Kotani 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh Company (72) Ikuko Yamada 1-3-6 Nakamagome, Ota-ku, Tokyo Stock Company Ricoh ( 72) Inventor Takanori Tsukiki Ricoh Co., Ltd. 1-3-6 Nakamagome, Ota-ku, Tokyo

Claims (11)

[Claims] 1. A quinacridone pigment represented by the following general formula (1) as a coloring agent in a recording ink containing water and a water-soluble organic solvent as main components: a coloring agent dispersed or dissolved in water; A dispersant containing at least one phthalocyanine pigment represented by (2) and a polymer dye having an average molecular weight of 5,000 to 150,000 obtained by salting a basic dye into a polymer compound having a sulfonic acid group; Recording polymer ink having a hydrophilic part and a hydrophobic part and / or a surfactant having an alkyl group having 6 or more carbon atoms. Embedded image (In the formula, R ₁ and R ₂ represent an alkyl group, a halogen atom or a hydrogen atom.) (Wherein, M represents a copper, iron, nickel or hydrogen atom,
X represents a hydrogen atom or a halogen atom. p is from 0 to 8
Represents an integer. ) 2. The recording ink according to claim 1, further comprising a nonionic surfactant having a polyoxyalkylene group as at least one of the surfactants. 3. A pigment having a particle size of 0.01 μm to 0.1 μm.
3. The recording ink according to claim 1, wherein the thickness of the recording ink is .mu.m. 4. The recording ink according to claim 1, further comprising titanium oxide fine particles having a particle diameter of 0.1 μm or less together with the pigment and the polymer dye. 5. The pigment is a quinacridone pigment represented by the general formula (1), and the high molecular dye is a salt of a high molecular compound having a sulfonic acid group with a basic dye represented by the following chemical formula (3). 5. The recording ink according to claim 1, wherein the recording ink is a high molecular dye. Embedded image 6. The pigment is a phthalocyanine pigment represented by the general formula (2), and the polymer dye is formed by salting a polymer compound having a sulfonic acid group with a basic dye represented by the following chemical formula (4). 5. The recording ink according to claim 1, wherein the recording ink is a polymer dye. Embedded image 7. The nonionic surfactant having a polyoxyalkylene group is at least one of surfactants represented by the following general formulas (5), (6), (7) and (8). The recording ink according to claim 2, 3, 4, 5, or 6, wherein Embedded image (In the formula, R ₃ represents a carbon chain having 6 to 14 carbon atoms which may be branched, and k represents an integer of 5 to 20.) (In the formula, m and n represent an integer of 0 to 20.) (In the formula, R ₄ represents an optionally branched carbon chain having 6 to 14 carbon atoms, and n represents an integer of 5 to 20.) (In the formula, R ₅ represents a carbon chain having 6 to 14 carbon atoms which may be branched, and m and n each represent an integer of 0 to 20. However, both m and n do not become 0.) 8. A high molecular dye obtained by forming a basic dye into a high molecular compound comprising a copolymer having p-styrenesulfonic acid and hydroxyethyl methacrylate or hydroxyethyl acrylate as basic units. Claim 1, 2, 3,
The recording ink according to 4, 5, 6 or 7. 9. The recording ink according to claim 2, further comprising at least one of urea and a urea derivative together with the nonionic surfactant. 10. The recording ink according to claim 1, comprising at least one pyrrolidone derivative as a water-soluble organic solvent. 11. The recording ink according to claim 1, which is jetted as fine droplets by thermal energy or mechanical energy, and the recording ink is 2.0 g / m 2 on a recording paper having a Steckigt sizing degree of 3 seconds or more. A recording method wherein an image having a resolution of 10 dots / mm × 10 dots / mm or more is formed by applying ^{2 to} 20 g / m ² .