JP2002003759A - Inkjet recording ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable water-based inkjet recording ink having good concealing properties as a white ink and high reliability. PROBLEM TO BE SOLVED: To provide a colorant, an organic solvent for dissolving or dispersing the same, and water, comprising at least one organic white pigment having a particle diameter of 0.01 to 0.3 μm as a colorant and a dispersant for dispersing the same. It was done. Further, it contains a resin emulsion having a self-film-forming action as a fixing agent.
Further, it contains a penetrant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink suitable for ink-jet recording, and more particularly to an ink composition useful for forming a color image on so-called plain paper.

[0002]

2. Description of the Related Art In recent years, ink jet printers have become popular because of their advantages such as low noise and low running cost, and color printers capable of printing on plain paper have also been put on the market. Each company is working to improve the quality of color images, improve the quality of photographs with dark and light inks, and improve the quality of images with smaller droplets. The reference inks are four colors of black, yellow, magenta, and cyan, but special colors such as orange and green may be provided depending on the application.

[0003] Japanese Patent Application Laid-Open No. 10-129014 discloses a printing method for improving the image quality of an ink-jet printed image using a combination of white ink and conventional four-color ink. However, the composition of the white ink is not considered at all here. Japanese Patent Application Laid-Open
JP-A-41370 discloses an oil-based inkjet ink using titanium oxide as a colorant, but is used for industrial purposes and is not preferable for use with the current aqueous inkjet ink.

Japanese Patent Application Laid-Open No. 8-48930 discloses an aqueous ink for writing implements containing an organic white pigment, but it is used only as an extender pigment, and its physical properties and the like are suitable for use as a white ink or ink jet. I didn't.

[0005]

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide an aqueous ink jet recording ink which satisfies various characteristics as an ink jet ink and has high concealing properties and high reliability as a white ink. .

A second object of the present invention is to provide a white aqueous ink jet recording ink having improved scratch resistance on a recording medium having low permeability. Third of the present invention
It is an object of the present invention to provide a white aqueous ink jet recording ink which is permeable to so-called uncoated paper having fibers exposed on the surface. A fourth object of the present invention is to specify a compound structure which is preferable as an organic white pigment. By using this, it is possible to provide a highly concealable and highly reliable ink jet recording ink as a white ink.

A fifth object of the present invention is to provide an ink jet recording ink which improves the storage stability of a conventional white ink by using an organic white pigment in combination with a conventionally used inorganic white pigment. A sixth object of the present invention is to specify the structure of an anionic surfactant which is preferably used for the purpose of increasing the permeability in the ink. This provides a white aqueous inkjet recording ink that can control the degree of proper permeability to paper.

[0008] A seventh object of the present invention is to provide an embodiment of a counter ion for improving the storage stability of the surfactant. An eighth object of the present invention is to specify the structure of a nonionic surfactant which is preferably used for the purpose of increasing the permeability in the ink. This provides a white aqueous inkjet recording ink that can control the degree of proper permeability to paper. A ninth object of the present invention is to specify the type of organic solvent suitably used for imparting permeability to the ink. This provides a white aqueous inkjet recording ink that can control the degree of proper permeability to paper.

[0009] A tenth object of the present invention is to provide a white water-based ink-jet ink which stabilizes the interaction between the activator and the dye in the ink and has improved storage stability and penetrability. An eleventh object of the present invention is to provide a suitable wetting agent capable of improving the dispersion stability of a pigment and the affinity for paper in the ink. First of the present invention
The second object is to present physical properties of the ink necessary for obtaining the storage stability of the ink composition. A thirteenth object of the present invention is to provide a recording method for forming an image satisfactorily using the ink.

[0010]

Means for Solving the Problems In a conventional white pigment ink mainly using an inorganic pigment such as titanium oxide, the sedimentation of the pigment is remarkable, and both the concealing property and the reliability are required because the specific gravity is large because the specific gravity is large. It was difficult. On the other hand, in the present invention, an aqueous inkjet ink capable of achieving both concealability and reliability by using an organic white pigment having a thickness of 0.01 to 0.3 μm was able to be obtained.

This is because organic white pigments having a specific gravity of less than 1.5 can be obtained as compared with the conventional specific gravity of 3.9 of titanium oxide, so that a surfactant or a polymer dispersant is used so that the particle diameter becomes 0.01 to 0.3 μm. It was clarified that the clogging resistance was remarkably improved by preparing the ink by adjusting by dispersing in the presence of. Particularly preferred organic white pigments are pigments represented by the following general formula (I).

[0012]

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(Where R is a hydrogen atom or a carbon number 1-4)
Represents an alkyl or alicyclic group. R _{1 to} R ₄ represent the same or different hydrogen atoms or lower alkyl groups having 1 to 4 carbon atoms, and R ₁ , R ₂ or R ₃ and R ₄ may form a heterocyclic group together with a nitrogen atom. . X represents a lower alkylene group having 2 or 3 carbon atoms. More specifically, R in the formula (I) is a hydrogen atom,
Compounds having a substituent of a methyl group, an ethyl group, a propyl group, or a butyl group can be used. R ₁ , R ₂ , R ₃ , and R ₄ also include a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group, and R ₁ and R ₂ or R ₃ and R ₄ are a heterocyclic group together with a nitrogen atom. A group may be formed, and examples thereof include a piperidyl group and a morpholino group. X may be not only an ethylene group but also a propylene group.

The amount of the organic white pigment represented by the general formula (I) is preferably 1 to 10% by weight based on the total amount of the ink.
If the amount used is less than 1% by weight, a sufficient color-developing effect cannot be obtained, and if the amount used is more than 10%, the viscosity increases and printing cannot be performed depending on the system. Examples of the organic white pigment include known ethylene-bis-melamine (trade name: Shigenox OWP, manufactured by Hakkor Chemical Co., Ltd.).

[0015]

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In the present invention, polyoxyethylene alkyl ether acetate (II) as an anionic surfactant and / or having 5 to 7 carbon chains are used for the purpose of enhancing the permeability to paper.
Dialkyl sulfosuccinic acid having a branched alkyl chain
By adding (III), the surface tension can be reduced to 50 mJ / m ² or less, the wettability between the ink and the paper surface can be improved, and an image can be formed on uncoated paper in which fibers are exposed.

R ₅ -0- (CH ₂ CH ₂ O) mCH ₂ COOM---(II) (where R5 is an alkyl group having 6 to 14 carbon atoms and may be branched, m: 3 to 12 M: alkali Metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine)

[0018]

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(Provided that R ₆ and R ₇ are branched alkyl groups having 5 to ₇ carbon atoms, M is an alkali metal ion, quaternary ammonium, quaternary phosphonium, or alkanolamine). It has been found that the use of lithium ion, quaternary ammonium and quaternary phosphonium represented by the following general formula as counter ions shows excellent dissolution stability.

[0020]

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(L: nitrogen or phosphorus, R _{8 to} R ₁₁ : hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a halogenated alkyl group) In the present invention, polyoxy is used as a nonionic surfactant. By adding an activator of the general formula (V) which is an ethylene alkylphenyl ether and a general formula (VI) which is an acetylene glycol-based surfactant, the surface tension is increased to 50 mJ.
/ m ² or less, and an image can be formed on uncoated paper in which the fibers are exposed.

The addition of urea and urea derivatives such as hydroxyethyl urea and dihydroxyethyl urea in addition to these activators (V) and (VI) weakens the interaction between the dye and the nonionic activator and reduces the association of the dye. It was found that it was possible to improve the permeability and to improve the ejection stability and the long-term storage property. It is preferable to use these urea derivatives in an amount of 0.1% to 10%. If it is 0.1% or less, there is no effect, and if it is 10% or more, it may affect the viscosity change during water evaporation.

The storage stability of the ink can be obtained by adjusting the pH of the ink from 6 to 11. If it is less than 6, corrosion of the metal member is likely to occur, and if it exceeds 11, the resin member is deteriorated. However, if the pH is 9 or more,
In the case of the activator (III), a change in physical properties due to decomposition is likely to occur, and when (III) is used, the pH is preferably adjusted to 6 to 9.

Compound (II) which can be used in the present invention,
When the amount of (III) is in the range of 0.05 to 10% by weight, it is possible to give desired permeability to the ink characteristics required by the printer system. Here, when the content is 0.05% or less, sufficient wettability is not exhibited, and when 10% by weight or more is added, the compound itself is likely to precipitate at a low temperature, and the precipitation of the compound (I) may occur, so that the reliability is increased. Gets worse. Next, the surfactants (II) and (III) used in the present invention are specifically shown in free acid form.

[0025]

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The water-soluble dyes and surfactants of the present invention have counter ions of lithium and sodium for the purpose of obtaining the stability of dissolution during storage and for improving the reliability in the recording method of discharging by applying thermal energy. , Quaternary ammonium or quaternary phosphonium, or alkanolamine ion. For example, in the case of a lithium salt, this can be carried out by adding lithium hydroxide. For the quaternary ammonium, phosphonium and alkanolamine cations of the general formula (IV), specifically, the following hydroxides are added. This is done by:

[0027]

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(C ₂ H ₅ OH) 3N · H + (IV-9) triethanolamine cation In the present invention, all the counter ions of the dye and the activator are sodium, lithium and / or It need not be a compound of IV), and can be mixed with other alkali ions. It is preferable to add sodium or lithium and / or the ion of the compound of the general formula (IV) in an amount of 30% or more, more preferably 50% or more, based on the number of moles of the activator.

The ink of the present invention uses water as a liquid medium. However, in order to obtain desired physical properties of the ink, to prevent drying of the ink, and to improve the dissolution stability of the compound of the present invention. The following water-soluble organic solvents can be used for such purposes as:

Ethylene glycol, diethylene glycol
, Triethylene glycol, polyethylene glycol
, Polypropylene glycol, 1,5 pentanediol, 1,6 hexanediol, glycerol, 1, 2,
6-hexanetriol, 1,2,4-butantrio
Polyhydric alcohols such as 1,1,2-butanthrol and petriol, ethylene glycol monoethyl ether
Polyvalent alcohol alkyl ethers such as ter, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether , Ethylene glyco-
Polyvalent alcohol aryl ethers such as rumonophenyl ether and ethylene glycol monobenzyl ether;
N-methyl-2-pyrrolidone, N-hydroxyethyl-
Nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, ε-caprolactam; amides such as formamide, N-methylformamide, formamide, N, N-dimethylformamide; monoethanol- Amines such as diamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine; sulfur-containing compounds such as dimethyl sulfoxide, sulfolane, and thiodiethanol; propylene carbonate; ethylene carbonate; and γ-butyrolactone. It is. These solvents are used alone or in combination with water.

Of these, particularly preferred are diethylene glycol, thiodiethanol, polyethylene glycol 200 to 600, triethylene glycol, glycerol, 1,2,6-hexanetriol, 1, Two, four
-Butanthrol, petriol, 1,5-pentaneddiol, N-methyl-2-pyrrolidone, N-hydroxyethylpyrrolidone, 2-pyrrolidone, 1,3 dimethylimidazolidinone. An excellent effect is obtained on the high solubility of the compound and the prevention of poor jetting characteristics due to water evaporation. Particularly, in the present invention, a preferable solvent for obtaining the dispersion stability of the compound (I) is a pyrrolidone derivative such as N-hydroxyethyl 2-pyrrolidone.

The activators (II), (III),
In addition to (V) and (VI), the penetrant added for the purpose of adjusting the surface tension is diethylene glycol monophenyl ether.
Ter, ethylene glycol monophenyl ether, ethylene glycol monoallyl ether, diethylene glycol monophenyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether
Alkyl and aryl ethers of polyhydric alcohols such as ter, tetraethylene glycol chlorophenyl ether, polyoxyethylene polyoxypropylene block copolymer, fluorine-based surfactant, ethanol, -Lower alcohols such as propanol, hexanediol, 2-
Ethyl-1,3 hexanediol (octanediol)
Examples thereof include diols having 6 or more carbon atoms, such as diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and 2-ethyl-1,3 hexanediol. The surface tension in the present invention is an index indicating permeability to paper, and particularly indicates a dynamic surface tension in a short time of 1 second or less after the surface is formed, and is different from a static surface tension measured in a 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 and the like. It measured using the surface tensiometer. Surface tension value is 5
It is preferably at most 0 mN / m, more preferably at most 40 mN / m, so that excellent drying properties can be obtained.

Other chromatic colorants can be used in combination with the organic white pigment of the present invention. As the coloring agent, in addition to the compounds of the general formulas (I) and (II), if necessary, a mixture with another coloring agent can be used. As the water-soluble dye to be used, dyes classified into acid dyes, direct dyes, basic dyes, reactive dyes and food dyes in color index and having excellent water resistance and light resistance are used. These are added to the extent that the effect is not alienated. Specific examples of these dyes include C.I.
I. Acid. Yellow 17,23,42,44,7
9, 142 C.I. I. Acid. Red 1,8,13,14,1
8, 26, 27, 35, 37, 42, 52, 82, 8
7, 89, 92, 97, 106, 111, 114, 11
5,134,186,249,254,289 C.I. I. Acid. Bull 9, 29, 45, 92, 2
49 C.I. I. Acid. Black 1,2,7,24,2
6,94 C.I. I. Hood. Yellow 3,4 C.I. I. Hood. Red 7, 9, 14 C.I. I. Hood. Black 1,2 As direct dye C.I. I. direct. Yellow-1, 12, 24, 26,
33, 44, 50, 86, 120, 132, 142,
144 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 26,29,62,
102 C.I. I. direct. Bull 1, 2, 6, 15,
22, 25, 71, 76, 79 86, 87, 90, 98, 163, 165, 199, 2
02 C.I. I. direct. Black 19,22,32,3
8, 51, 56, 71, 74, 75, 77, 154, 1
68,171 as basic dyes; I. Basic. Yellow-1, 2, 11, 1
3,14,15,19,21,23,24,25,2
8, 29, 32, 36, 40, 41, 45, 49, 5
1,53,63,64,65,67,70,73,7
7, 87, 91 C.I. I. Basic. Red 2,12,13,1
4,15,18,22,23,24,27,29,3
5,36,38,39,46,49,51,52,5
4,59,68,69,70,73,78,82,10
2,104,109,112 C.I. I. Basic. Blue 1,3,5,7,
9,21,22,26,35,41,45,47,5
4,62,65,66,67,69,75,77,7
8,89,92,93,105,117,120,12
2,124,129,137,141,147,155 C.I. I. Basic. Black 2,8 As a reactive dye, C.I. I. Reactive. Black 3,4,7,11,
12, 17 C.I. I. Reactive. Yellow 1,5,11,1
3,14,20,21,22,25,40,47,5
1, 55, 65, 67 C.I. I. Reactive. Red 1,14,17,2
5,26,32,37,44,46,55,60,6
6, 74, 79, 96, 97 C.I. I. Reactive. Bull 1, 2, 7, 14,
15, 23, 32, 35, 38, 41, 63, 80, 9
5 etc. can be used. Particularly, acid dyes and direct dyes can be preferably used. In addition, a dye manufactured by Zeneca developed for inkjet can be preferably used. Specific examples include Projet Fast Cyan 2, Yellow 2, Magenta 2, and Black 2.

As the pigment, azo-based, phthalocyanine-based, anthraquinone-based, dioxazine-based, and organic pigments can be used.
Indigo-based, thioindigo-based, perylene-based, isoindolenone-based, aniline black, azomethine-based, rhodamine B lake pigment, carbon black, and the like.Examples of inorganic pigments include iron oxide, titanium oxide, and calcium carbonate. Examples include barium sulfate, aluminum hydroxide, barium yellow, navy blue, cadmium red, chrome yellow, and metal powder.

As the white inorganic pigment, titanium oxide and surface-treated titanium oxide are preferable.
Lead white, lead sulfate, lipotone, zinc sulfide, antimony oxide,
Lead zinc white, basic sulfate, lead silicate, zircon oxide, barium metaborate, Patchonson white, manganese white, tin oxide,
Tungten white, calcium plumbate, or a mixture thereof can be used as appropriate. These inorganic white pigments are preferably dispersed so as to have a particle size of 0.05 to 0.5 μm and contained in the ink in an amount of 1 to 10% by weight.

As the pigment dispersant used in the present invention, as a hydrophilic polymer, in the natural system, gum arabic, tragan gum, guar gum, karaya gum, locust bean gum, arabinogalactone, pectin, quinceed starch, etc. Vegetable macromolecules, alginic acid, carrageenan,
Seaweed polymers such as agar, animal polymers such as gelatin, casein, albumin and collagen; microbial polymers such as xanthen gum and dextran; and semi-synthetic systems, methylcellulose, ethylcellulose and hydroxyethyl Cellulose, hydroxypropyl cellulose, carboxymethyl cellulose and other fibrous polymers, starch glycol
Starch-based polymers such as sodium alginate and sodium starch phosphate; seaweed-based polymers such as sodium alginate and propylene glycol alginate; and purely synthesized systems include polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, etc. Vinyl polymer,
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, alkali metal salts of β-naphthalenesulfonic acid formalin condensate, high molecular compounds having a cationic functional group salt such as quaternary ammonium or amino group in the side chain, natural high molecular compounds such as shellac, etc. No.

In the ink of the present invention, conventionally known additives can be added in addition to the above colorants and solvents.
For example, as a preservative and fungicide, sodium dehydroacetate,
Sodium sorbate, sodium 2-pyridinethiol-1-oxide, sodium benzoate, sodium pentachlorophenol, and the like can be used in the present invention.

As the pH adjuster, any substance can be used as long as it can adjust the pH to 7 or more without adversely affecting the ink to be prepared. Examples thereof include amines such as diethanolamine and triethanolamine, hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, ammonium hydroxide, quaternary ammonium hydroxide, and quaternary ammonium hydroxide. And alkali metal carbonates such as graded phosphonium hydroxide, lithium carbonate, sodium carbonate and potassium carbonate.

Examples of the chelating reagent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uramildiacetate.

As the rust preventive, for example, acid sulfite,
Examples include sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite. In addition, a water-soluble ultraviolet absorber, a water-soluble infrared absorber, and a surfactant can be added according to the purpose.

[0041]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples and comparative examples of the present invention are shown below. Example 1 The compound of the specific example (VII) was dispersed with an ultrasonic homogenizer in the presence of a dispersant styrene acrylic polymer to a particle size of 0.1 μm or less, and a composition having the following formulation was prepared using this dispersion. It was prepared by dissolving with stirring, and adjusted with a 10% aqueous solution of lithium hydroxide so that the pH became 8.5.
Ink 1 was prepared by filtration with a μm Teflon (registered trademark) filter.

5.5% by weight of compound of specific example (VII) 0.8% by weight of compound of specific example (II-1) 0.4% by weight of styrene-acrylic acid polymer 5% by weight of glycerol N-hydroxyethylpyrrolidone 5% by weight 2-ethyl-1,3 hexanediol 1% by weight Sodium dehydroacetate 0.2% by weight Deionized water Remaining Example 2 The same procedure as in Example 1 was carried out except that the following composition was used, and the pH was changed to sodium hydroxide. Was adjusted to 8.8 to adjust ink 2.

Compound of specific example (VII) 4.0% by weight Titanium oxide (particle diameter 0.1 to 0.6 microns) 0.5% by weight Polyacrylic acid 0.5% by weight 1,2,6-hexanetriol 4% by weight 1 8,5-pentanediole 8% by weight Diethylene glycol monobutyl ether 5% by weight Activator of specific example (V) R12 = C9H19, K = 12 1.2% by weight Specific example (III-1) 25% aqueous solution 0.8% by weight Sodium alginate 0.05% by weight Urea 5% by weight 2-Pyridinethiol-1-oxide sodium 0.2% by weight Ion-exchanged water Remaining Example 3 The compound of Example (VII) was used as a dispersant for sodium styrene acrylic acid polymer. Dispersion treatment was performed using a salt with a nanomizer to obtain a dispersion, and the dispersion was obtained in the same manner as in Example 1.
The pH was adjusted to 8.5 with lithium hydroxide to prepare Ink 3.

Compound of specific example (VII) 6% by weight Diethylene glycol 5% by weight Glycerol 5% by weight Styrene acrylic acid polymer 0.5% by weight Activator of (V) R: C9H19 k: 122 2% by weight Specific Example (III-3) 25% aqueous solution 0.2% by weight Sodium dehydroacetate 0.2% by weight Deionized water Remaining Example 4 The same procedure as in Example 3 was carried out except that the following composition was used.
Was adjusted to 9.5 with lithium hydroxide to prepare Ink 4.

Compound of specific example (VII) 5% by weight Ethylene glycol 5% by weight Glycerol 2% by weight 1,5-pentanediol 8% by weight 2-pyrrolidone 2% by weight Acrylic emulsion (50% solid content) 4 % By weight Polyoxyethylene polyoxyethylene block copolymer 1% by weight Activator of (VI) m, n = 20 0.8% by weight Specific example (III-4) 25% aqueous solution 2% by weight urea 5% by weight benzoic acid 0.2% by weight of sodium ion-exchanged water Remaining Example 5 The same procedure as in Example 1 was carried out except that the following composition was used.
Was adjusted to 7.8 with sodium hydroxide to prepare Ink 5.

Direct Yellow 132 2% by weight Compound of specific example (VII) 3.2% by weight Triethylene glycol 5% by weight Petriol 10% by weight N-methyl-2-pyrrolidone 5% by weight Specific example (IV-5) Activator 2% by weight Specific Example (III-2) 25% aqueous solution 1.5% by weight Hydroxyethyl urea 5% by weight Sodium 2-pyridinethiol-1-oxide 0.2% by weight Ion-exchanged water Remaining Example 6 Except using the following composition, it carried out similarly to Example 1, and carried out pH adjustment.
Was adjusted to 8 with lithium hydroxide to prepare Ink 6.

Pigment Red 122 2% by weight Specific example (VII) Compound 1.5% by weight 2-Pyrrolidone 8% by weight Glycerol 7% by weight (VII) Activator m + n = 151 1% by weight (VII) Activator m + n = 0 1% by weight Specific example (III-7) 25% aqueous solution 2% by weight hydroxyethyl urea 5% by weight sodium dehydroacetate 0.2% by weight Deionized water Remaining Example 7 The same as Example 1 except that the following composition was used. Similarly, pH
Was adjusted to 8 with lithium hydroxide to prepare ink 7.

Pigment Blue 15: 3 3% by weight Compound 3% by weight of specific example (VII) N-methyl-2-pyrrolidone 8% by weight 1,5-pentanediole 8% by weight Activity of specific example (II-4) 0.8% by weight of sodium benzoate 0.5% by weight of ion-exchanged water Remaining Example 8 The same procedure as in Example 1 was carried out except that the following composition was used.
Was adjusted to 7.5 with lithium hydroxide to obtain Ink 8.

Cavojet 300 (self-dispersion type carbon dispersion manufactured by Cabot) 15% by weight Compound of specific example (VII) 1.0% by weight Thiodiethanol 5% by weight Glycerol 10% by weight Activator of (V) R: C10H21 k : 12 1.5% by weight sodium benzoate 0.5% by weight Deionized water Remaining Example 9 The same procedure as in Example 1 was carried out except that the following composition was used.
Was adjusted to 8 with lithium hydroxide to obtain ink 9.

Projet Fast Cyan 2 (Dye made by Zeneca) 3% by weight Compound of specific example (VII) 3% by weight 2-pyrrolidone 5.0% by weight Glycerol 15.0% by weight Activator of (VII) m + n = 40 1.0% by weight Activator of specific example (IV-2) 1.0% by weight Sodium pentachlorophenol 0.2% by weight Ion-exchanged water Remaining Example 10 Except for using the following composition, Example 1 PH
Was adjusted to 8 with lithium hydroxide to obtain ink 9.

Projet Fast Yellow 2 (Dye manufactured by Zeneca) 2.0% by weight Specific compound (VII) 1.0% by weight 2-pyrrolidone 5.0% by weight Glycerol 15.0% by weight Activator of (VII) m + n = 40 2.0% by weight Activator of specific example (V-2) 1.0% by weight Sodium dehydroacetate 0.2% by weight Deionized water Remaining amount Comparative example 1 In Example 1, the compound of specific example (VII) was added. Ink 11 was prepared in the same manner except that titanium oxide (particle size: 0.5 to 1.3 microns) was used instead. Comparative Example 2 Ink 12 was prepared in the same manner as in Example 2 except that titanium oxide (particle diameter: 0.8 to 1.2 μm) was used instead of the compound of Example (VII). Comparative Example 3 Ink 13 was prepared in the same manner as in Example 3, except that titanium oxide (particle diameter: 2 μm) was used instead of the compound of Example (VII). Comparative Example 4 An ink 14 was prepared in the same manner as in Example 4 except that the surface-treated titanium oxide (particle diameter: 0.9 to 1.5 μm) was used instead of the compound of Example (VII).

Next, the above Examples 1 to 10 and Comparative Examples 1 to
4 was subjected to the following test. 1) Clearness of image Nozzle diameter of thermal ink jet system 45 μm, 30
Printing was performed by an inkjet printer having 128 nozzles of 0 dpi and an inkjet printer having a nozzle diameter of 33 μm and 256 nozzles using the laminated PZT for pressurizing the liquid chamber flow path, and the sharpness was visually judged.
With respect to the white ink, the printing paper was printed on black and dark blue high-quality paper commercially available, high-quality paper on which other chromatic colors were printed by ink jet printing, font paper, and recycled paper, and the concealment was confirmed. The chromatic inks were printed on high-quality paper, font paper, and recycled paper in single color and two-color overlap, and the sharpness was evaluated. When there was no problem with any of the papers, it was evaluated as ○, when the paper did not conform to the paper, as で き な い, and when none of the papers could be handled, as ×. 2) Image Water Resistance The 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 (color resistance%) was determined by the following equation.

[0053] Regarding any of the papers, ○ indicates less than 20%, Δ indicates less than 30%, and X indicates 30% or more.

3) Drying property of image The filter paper was pressed against the printed image under certain conditions, and the time until the ink was not transferred to the filter paper was measured.

When any of the papers was dried within 10 seconds, it was judged as ○. Anything above that is marked as x. 4) Storage stability Put each ink in a polyethylene container and store at -20 ° C, 5 ° C,
After storage at 20 ° C. and 70 ° C. for 3 months under each condition, the surface tension, viscosity, and the presence or absence of precipitates after storage were examined. No change in physical properties and the like was observed regardless of the conditions of storage.

5) Reliability at the time of printing pause A printer having a head driven by PZT having a nozzle diameter of 30 μm and 128 nozzles is used, and even if printing is paused without capping or cleaning during operation, the printing is restored. The results of evaluating the reliability and evaluating the reliability of the ejection direction or the change in the weight of the ejected droplets are shown in the table. No problem ○, small change in drop weight, small bending △, noticeable clogging ×

[0057]

[Table 1]

[0058]

According to the present invention, an aqueous ink jet recording ink which satisfies various characteristics as an ink jet ink and has good concealing properties and high reliability as a white ink can be obtained. Recording with reproducibility can be performed. According to the present invention, it is possible to perform recording even on a film-based chromatic recording medium by providing a white aqueous inkjet recording ink having improved abrasion resistance for a recording medium having low permeability. .

According to the present invention, by providing a white aqueous ink jet recording ink which is permeable to so-called non-coated paper having fibers exposed on the surface, the drying time can be reduced and high-speed printing can be performed. According to the present invention, by specifying a compound structure that is preferable as an organic white pigment, a white ink that does not cause clogging even when left for a long time with high concealing properties and high reliability as a white ink by using the same is used. It can be provided and the load on the maintenance mechanism can be reduced.

According to the present invention, the storage stability of a conventional white ink can be improved by using an organic white pigment in combination with a conventionally used inorganic white pigment, and the improvement from the conventional system can be smoothly performed. Can be. According to the present invention, the structure of an anionic surfactant preferably used for the purpose of enhancing permeability in the ink is specified,
Accordingly, by providing a white aqueous inkjet recording ink capable of controlling appropriate permeability to paper, high-speed printing can be more efficiently supported.

According to the present invention, there is provided an embodiment of a counter ion for improving the storage stability of the anionic surfactant, and to provide an aqueous ink-jet ink which ensures the storage stability and can be stably ejected even after a long pause. Can be.

According to the present invention, it is possible to specify the structure of a nonionic surfactant which is preferably used for the purpose of increasing the permeability in the ink, and thereby to control the appropriate permeability to the paper. Providing the white aqueous inkjet recording ink enables more efficient high-speed printing. According to the present invention, a type of an organic solvent suitably used for the purpose of imparting permeability to the ink is specified, and thereby a white aqueous inkjet recording ink capable of controlling an appropriate degree of permeability to paper is provided. It can provide high-speed printing efficiently.

According to the present invention, the use of a urea derivative stabilizes the interaction between the activator and the colorant in the ink, thereby providing a white aqueous ink jet ink having improved storage stability and penetrability. it can. According to the present invention, by using a pyrrolidone derivative in the ink, the dispersion stability of the pigment and the affinity for paper can be increased. According to the present invention, storage stability can be obtained by specifying the pH range of the ink.

According to the present invention, it is possible to provide a recording method for favorably forming an image using the ink. This makes it possible to perform printing on chromatic color paper and ink-jet recording with improved gradation, which could not be obtained conventionally.

Continued on the front page (72) Inventor Masayuki Koyano 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Hitoshi Arita 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. F-term (reference) 2C056 EA13 FA03 FA04 FC02 2H086 BA52 BA55 BA59 4J039 AE07 BC12 BC13 BC33 BC37 BC50 BC52 BC54 BC56 BE01 BE12 BE15 BE22 BE28 CA06 EA18 GA24

Claims (13)

[Claims] An organic white pigment comprising a colorant, an organic solvent for dissolving or dispersing the same, and water and containing at least one organic white pigment having a particle size of 0.01 to 0.3 μm and a dispersant for dispersing the same as a colorant. A recording ink for ink-jet recording, characterized in that: 2. The ink jet recording ink according to claim 1, wherein the ink contains a resin emulsion having a self-film-forming action as a fixing agent. 3. The ink jet recording ink according to claim 1, wherein the ink further contains a permeability imparting agent. 4. The ink jet recording ink according to claim 1, wherein the organic white pigment is an alkylenebismelamine derivative represented by the general formula (I). Embedded image (Wherein, R represents .R ₁ to R ₄ representing a hydrogen atom or Arukiruki or alicyclic group having 1 to 4 carbon atoms represents the same or different hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, R ₁ , R ₂ or R ₃ or R ₄ may form a heterocyclic group together with a nitrogen atom. X represents a lower alkylene group having 2 or 3 carbon atoms.) 5. The ink according to claim 1, wherein an inorganic white pigment is further added as a colorant in the ink.
Or the ink-jet recording ink according to 4. 6. The ink jet recording ink according to claim 3, wherein polyoxyethylene alkyl ether acetate (II) or dialkyl sulfosuccinate (III) is added as a penetrant. _{(Wherein, R 5 -0- (CH 2 CH} 2 O) mCH 2 COOM - - - (II) R 5: an alkyl group which may be branched having 6 to 14 carbon atoms,
m: 3 to 12 M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine) (However, R ₆ and R ₇ : a branched alkyl group having 5 to ₇ carbon atoms M: alkali metal ion, quaternary ammonium, quaternary phosphonium, alkanolamine) 7. The compound (II) or (III) wherein the counter ion is sodium, lithium and / or a quaternary ammonium, quaternary phosphonium or alkanolamine cation represented by the general formula (IV). Claim 6 characterized in that:
The ink for inkjet recording according to the above. Embedded image (However, L: nitrogen or phosphorus, R ₈ to R _11: hydrogen, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a halogenated alkyl group) 8. The following general formulas (V) and (V)
3. The ink jet recording ink according to claim 2, which contains the surfactant (I). Embedded image (Where R ₁₂ is a 6 to 14 carbon chain which may be branched)
k: 5-12) (However, m and n are 0 to 40) 9. The ink jet recording apparatus according to claim 2, wherein the ink further comprises a polyhydric alcohol alkyl ether and a diol having 6 or more carbon atoms as a penetrating agent. ink. 10. The ink jet recording ink according to claim 8, wherein the aqueous ink contains urea and a urea derivative. 11. The method according to claim 1, wherein at least one pyrrolidone derivative is contained as a wetting agent.
11. The ink jet recording ink according to 3, 4, 5, 6, 7, 8, 9 or 10. 12. The method according to claim 1, wherein the pH is adjusted to 6 or more and 11 or less.
12. The ink for inkjet recording according to 9, 10, or 11. 13. The ink according to claim 1, which is jetted as fine droplets by thermal energy or mechanical energy, and is singly or superimposed on the same location as droplets of another hue. And a recording method in which an image is formed by attaching the recording medium to a recording medium having a Steckigt sizing degree of 3 seconds or more.