JP2003336001A - Organic pigment dispersion and method for manufacturing the same, aqueous coloring fluid and inkjet recording ink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment dispersion which does not require the long-term treatment by a dispersion apparatus, has high dispersion stability and the uniformity in size independently of the size of primary particles of a pigment as the raw material, is of the order of nanometer, and excels in transparency, a method for manufacturing the same, and an aqueous coloring fluid which excels in water resistance and light resistance, color development and light transmittance, particularly an inkjet recording fluid. <P>SOLUTION: The method for manufacturing the organic pigment dispersion comprises a dissolution step of dissolving an organic pigment and a dispersing agent in an acid or a mixed solution of an acid and an organic solvent and a deposition step of mixing the pigment solution obtained in the dissolution step with water to deposit the organic pigment. The organic pigment dispersion is obtained by this method. The aqueous coloring fluid, particularly the inkjet recording fluid contains this organic pigment dispersion. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording liquid for an inkjet printer, an aqueous coloring liquid suitable for this recording liquid, an organic pigment dispersion used in this recording liquid, and a method for producing the same.

[0002]

2. Description of the Related Art Ink jet recording systems form ink droplets by various ink ejection systems.
Recording is performed by adhering a part or all of them to a recording material such as paper, processed paper, plastic film, and woven cloth. Conventionally, an inkjet recording liquid is mainly an aqueous recording liquid containing a dye and a water-soluble additive, and is excellent in storage stability as an ink. Further improvements are being made in terms of light resistance and light resistance. Therefore, attempts have been made to improve the water resistance and light resistance by changing the coloring material from dye to pigment. However, compared with dye ink, pigment ink is often inferior in ejectability from the nozzle of the inkjet head, and because the pigment is not a single dye molecule like dye, but particles, scattered light and reflected light are mixed. Then
Absorption spectrum is broader than that of dyes, and color development is generally low. One of the methods to solve these problems is to make the pigment finer, and the pigment is made into fine particles on the order of nanometers (100 nanometers or less), which has almost no effect of light scattering and exhibits transmittance comparable to that of dyes. Is desired. Usually, the fine particles of the pigment are made by a mechanical force using a disperser such as a sand mill, a roll mill, and a ball mill, but in this method, there is a limit to miniaturizing the pigment to submicron order near the primary particles, It is difficult to reduce the particle size to the order of nanometers (JP-A-10-110111). Also, the smaller the particle size, the longer the dispersion time, and the more difficult it is to obtain uniform quality. Furthermore, since it is very difficult to make the pigment finer than the primary particles by this method, a pigment having large primary particles cannot be used as a raw material in order to obtain nanometer-order pigment particles. On the other hand, a method has been proposed in which the pigment is dissolved once and then re-precipitated to form fine particles of the pigment.
Japanese Unexamined Patent Publication No. 9-221616 proposes fine particle formation by an acid pasting method in which an organic pigment is once dissolved using sulfuric acid, but a pigment of nanometer order has not been obtained yet. In addition, Japanese Patent Publication No. 4-2970
No. 7, Japanese Patent Publication No. 6-4476 discloses a method in which an organic pigment is dissolved in an aprotic polar solvent in the presence of an alkali and then neutralized with an acid to obtain fine pigment particles. Since the operation of pigment miniaturization and dispersion stabilization treatment must be performed in two stages, the initially fine pigment particles have already agglomerated at the time of dispersion, and a pigment dispersion of substantially nanometer order is obtained. Is difficult.
In Japanese Patent Publication No. 5-27664, Japanese Patent Publication No. 6-33353, and Japanese Patent Publication No. 6-96679, an organic pigment and a dispersant such as a surfactant or a resin are dissolved together in an aprotic polar solvent in the presence of an alkali. Although it has been neutralized with an acid to obtain fine pigment particles with high dispersibility, the pigment is in a slurry state and cannot be prevented from associating with the pigment particles because it is further dried. Even if the dispersion treatment is carried out at 1, it is not possible to stably obtain a nanometer-order pigment having a regular size.

[0003]

Therefore, the object of the present invention is to solve the above-mentioned problems of the conventional method for producing a pigment dispersion, and do not require treatment with a dispersing device for a long time, and to make primary particles of a pigment as a raw material. It is intended to provide a nanometer-order pigment dispersion having high dispersion stability and size uniformity, which does not depend on the size of the pigment, and a method for producing the same. Another object of the present invention is to provide a water-based coloring liquid having excellent water resistance and light resistance, as well as excellent color developing properties and light transmission properties, particularly an inkjet recording liquid.

[0004]

Means for Solving the Problems As a result of intensive investigations by the present inventors, a dissolution step of dissolving an organic pigment and a dispersant in an acid or a mixed solution of an acid and an organic solvent, and a solution step obtained in the dissolution step It has been found that the above-mentioned problems can be solved by a method for producing an organic pigment dispersion, which comprises a precipitation step of precipitating the organic pigment by mixing a pigment solution with water. As a result, it is possible to eliminate the steps of drying and separating, and it is possible to deposit and disperse the organic pigment at the same time, and to provide a stable supply of pigment dispersion on the order of nanometers, which was not achieved by conventional technology. Is achieved.

In this method, it is preferable that the dispersant is a polymer compound or a surfactant having in the molecule at least one selected from a cationic nitrogen atom, a hydroxyl group and an alkylene oxide.

It is also preferable that the solubility of the organic solvent in water is 5% by mass or more.

It is also preferred that the acid is an organic protic acid.

The organic protonic acid is preferably one or more selected from alkyl sulfonic acids, alkyl carboxylic acids, halogenated alkyl sulfonic acids, halogenated alkyl carboxylic acids, aromatic carboxylic acids and aromatic sulfonic acids. .

It is also preferable that the acid is an inorganic protonic acid.

The inorganic protonic acid is one selected from sulfuric acid, nitric acid, phosphoric acid, polyphosphoric acid, hydrochloric acid, perchloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid and chlorosulfonic acid. The above is preferable.

It is also preferred that the acid is a Lewis acid.

The Lewis acid is aluminum, iron, copper,
Zinc, tin, gallium, boron, titanium, zirconium, indium, silicon, germanium, antimony,
It is preferably one or more kinds of halides selected from arsenic, tungsten, tantalum, zirconium and vanadium.

The present invention includes the organic pigment dispersion produced by the above method.

The present invention also includes an aqueous color liquor containing this organic pigment dispersion.

The present invention further includes an inkjet recording liquid containing the organic pigment dispersion.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Specific structural examples will be described below, but the present invention is not limited to the following methods.

As the organic pigment used in the present invention, any one can be used as long as it can be dissolved in an acid together with a dispersant, or can be dissolved in a mixed solution of an acid and an organic solvent. More preferably, a stable substance that does not exhibit reactivity under this condition is preferable. Specifically, organic pigments used in printing inks and paints can be used.
Azo type, disazo type, condensed azo type, anthraquinone type,
Dianthraquinonyl, anthrapyridine, ansanthrone, thioindigo, naphthol, benzimidazolone, pyranthrone, phthalocyanine, flavanthrone, quinacridone, dioxazine, diketopyrrolopyrrole, indanthrone System, isoindolinone type, isoindoline type, quinophthalone type, perinone type and perylene type pigments, vat dye pigments, metal complex pigments, and basic dye pigments. As an example, C.I. I. P
igment Yellow 1, same 2, same 3, same 1
2, ibid 13, ibid 14, ibid 16, ibid 17, ibid 55, ibid 7
3, ibid 74, ibid 75, ibid 81, ibid 83, ibid 93, ibid 9
5, the same 97, the same 98, the same 108, the same 109, the same 110,
114, 128, 129, 130, 138, 139, 150, 151, 154, 155, 158, 173, 180, 185, C.I. I. Pi
gment Red 5, the same 7, the same 12, the same 22, the same 3
1, 48 (Ca), 49 (Mn), 57 (C)
a), ibid 88, ibid 112, ibid 122, ibid 123, ibid 14
6, the same 150, the same 168, the same 171, the same 175, the same 17
6, the same 177, the same 181, the same 183, the same 184, the same 18
5, 202, 206, 207, 208, 20
9, 213, 254, 255, C.I. I. Pigm
ent Blue 1, the same 2, the same 3, the same 15, the same 16,
22, 25, 26, 56, 57, 60, 61, 66, C.I. I. Pigment Violet
19, 29, 38, 42, 43, 44,
C. I. Pigment Orange 16 and 3
6, 61, 66, C.I. I. Pigment Bro
There is wn 38. These organic pigments can be used alone or in combination of two or more.

The dispersant is one which is soluble in an acid alone or in a mixed solution of an acid and an organic solvent and is also soluble in water and has a dispersing effect on an organic pigment in an aqueous solution of the dispersant. The thing can be used suitably. Preferably, it is a polymer compound or a surfactant having one or more kinds of a cationic nitrogen atom, a hydroxyl group and an alkylene oxide in the molecule. More preferably, an acid alone or a compound that can be stably dissolved together with an organic pigment in an organic solvent in the presence of an acid is preferable. When the hydrophilic part of the dispersant is composed of only those selected from the above-mentioned ones such as carboxylic acid group, sulfonic acid group, and phosphoric acid group, the dispersion stability in the organic pigment dispersion containing an acid is relatively high. It is disadvantageous in that it becomes very low. Specifically, as the surfactant, a cationic surfactant such as an alkylamine salt, a dialkylamine salt, a tetraalkylammonium salt, a benzalkonium salt, an alkylpyridinium salt or an imidazolinium salt,
Nonionic interface such as polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, ethylene oxide adduct of acetylene glycol, ethylene oxide adduct of glycerin, polyoxyethylene sorbitan fatty acid ester In addition to the surfactants, amphoteric surfactants such as alkylbetaine and amidobetaine, silicone surfactants, fluorine surfactants, etc., are appropriately selected from conventionally known surfactants and derivatives thereof. be able to.

As a polymer compound that can be used as a dispersant
Specifically, styrene, styrene derivatives, vinyl vinyl
Phthalene, vinyl naphthalene derivative, α, β-ethylene
Of unsaturated alcoholic carboxylic acid such as aliphatic alcohol ester
Acrylic acid, acrylic acid derivative, maleic acid, maleic acid
Derivative, alkenylsulfonic acid, vinylamine, allyl
Amine, itaconic acid, itaconic acid derivative, fumaric acid,
Fumaric acid derivative, vinyl acetate, vinylphosphonic acid, vinyl
Nylpyrrolidone, acrylamide, N-vinylacetoa
From amide, N-vinylformamide and its derivatives, etc.
At least two or more selected monomers (of which less
One is a cationic nitrogen atom, a hydroxyl group and an alkyle.
Monomer having a functional group that becomes any of the oxides)
Block copolymer composed of or random copolymer
Coalesce, graft copolymer, or modified products thereof, and
These salts etc. are mentioned. Molecule with a cationic nitrogen atom
As a more specific example of the monomer contained therein,
N, N-dimethylaminoethyl methacrylate [CH₂=
C (CH₃) -COO-C₂H_FourN (CH₃)₂], N, N-di
Methylaminoethyl acrylate [CH₂= CH-CO
OC₂H_FourN (CH₃)₂], N, N-dimethylaminopro
Pill methacrylate [CH₂= C (CH₃) -COO-C₃
H₆N (CH₃)₂], N, N-dimethylaminopropyl acetate
Clearate [CH ₂= CH-COO-C₃H₆N (C
H₃)₂], N, N-dimethylacrylamide [CH₂= C
H-CON (CH₃)₂], N, N-dimethylmethacrylate
Mid [CH₂= C (CH₃) -CON (CH₃)₂], N, N-
Dimethylaminoethyl acrylamide [CH₂= CH-
CONHC₂H_FourN (CH₃)₂], N, N-dimethylamino
Ethylmethacrylamide [CH₂= C (CH₃) -CONH
C₂H_FourN (CH₃)₂], N, N-dimethylaminopropyl
Acrylamide [CH₂= CH-CONH-C₃H₆N (C
H ₃)₂], N, N-dimethylaminopropylmethacryl
Amide [CH₂= C (CH₃) -CONH-C₃H₆N (C
H₃)₂] Etc. are mentioned.

Further, natural polymer compounds such as albumin, gelatin, rosin, shellac, starch, gum arabic and sodium alginate, and modified products thereof can be preferably used as the dispersant. These dispersants can be used alone or in combination of two or more. The use ratio of the dispersant is not particularly limited, but is 0.0 per 1 part by mass of the organic pigment.
It is preferably used in the range of 5 to 5 parts by mass or more, and when an organic solvent is used, it is preferably used in the range of 50 parts by mass or less to 100 parts by mass of the organic solvent. When the dispersant is 50 parts by mass or less with respect to 100 parts by mass of the organic solvent, it is easy to completely dissolve the dispersant, which is preferable.
When the amount is 0.05 parts by mass or more based on 1 part by mass of the organic pigment, the dispersion effect is excellent, which is preferable. Further, it is preferable to use the dispersant in an amount of 5 parts by mass or less with respect to 1 part by weight of the organic pigment because the dispersion effect is excellently improved and the cost performance is excellent. The preferred molecular weight range of the polymer compound is not particularly limited, but is 200
〜100,000 is preferable, and further 2,000-600
It is preferably used in the range of 00. When the molecular weight of the polymer compound is 200 or more, the dispersing effect is excellent, which is preferable, and when it is 100000 or less, the solubility in the solvent is excellent, which is preferable.

As the organic solvent, any solvent can be used as long as it can dissolve the organic pigment and the dispersant in the presence of an acid, but those having a solubility in water of 5% by mass or more are preferably used. Further, those which can be freely mixed with water are preferable. Solubility in water is 5% by mass
When the pigment is solubilized using the above solvent, the organic pigment is likely to be precipitated when mixed with water, which is preferable for obtaining fine particles. It is also preferable in that the obtained pigment dispersion has good dispersion stability. Specifically, dimethyl sulfoxide, dimethyl imidazolidinone, sulfolane, N-methylpyrrolidone, dimethylformamide, acetonitrile, acetone, dioxane, tetramethylurea, hexamethylphosphoramide, hexamethylphosphorotriamide, pyridine, propionitrile, Butanone, cyclohexanone, tetrahydrofuran, tetrahydropyran, ethylene glycol diacetate, γ-butyrolactone, methanol, ethanol, n-propanol, isopropanol, n-butanol, nitromethane, nitroethane, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, propionic acid, etc. Examples of preferred solvents include dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, and dimethylimidazo. Jin Won, nitromethane, nitropropane, acetone or acetonitrile are preferred. Moreover, these can be used individually by 1 type or in combination of 2 or more types.

As the acid, any acid can be used as long as it can solubilize the organic pigment alone or in an organic solvent, but organic protic acid, inorganic protic acid and Lewis acid are preferable. Specifically, as the organic protonic acid, an alkyl sulfonic acid such as methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid, butane sulfonic acid; trifluoromethane sulfonic acid in which these are substituted with halogen, pentafluoroethane sulfonic acid, Halogenated alkylsulfonic acids such as heptafluoropropanesulfonic acid, nonafluorobutanesulfonic acid and trimethylsilyl trifluoromethanesulfonate; alkylcarboxylic acids such as formic acid, acetic acid, propionic acid and butanoic acid; trifluoroacetic acid substituted with halogen , Halogenated alkylcarboxylic acids such as trichloroacetic acid, chlorocaproic acid, bromocaproic acid and chloroundecanoic acid; aromatic carboxylic acids such as benzoic acid and tetrafluorobenzoic acid; benzenesulfonic acid, toluenesulfonic acid, Cyclohexylene sulfonic acid, naphthalenesulfonic acid, can be preferably used an aromatic sulfonic acids such as chlorobenzene sulfonic acid. As the inorganic protonic acid, sulfuric acid, nitric acid, phosphoric acid,
Polyphosphoric acid, hydrochloric acid, perchloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid and chlorosulfonic acid can be preferably used. In addition to these, phosphorous acid, hypophosphorous acid, phosphorous acid, pyrophosphoric acid, chlorous acid, hypochlorous acid, periodic acid,
Fuming sulfuric acid, fuming nitric acid, manganic acid, permanganic acid, chromic acid, dichromic acid, and various other solid acids can also be used.
As the Lewis acid, a halide of one or more substances selected from aluminum, iron, copper, zinc, tin, gallium, boron, titanium, zirconium, indium, silicon, germanium, antimony, arsenic, tungsten, tantalum, zirconium and vanadium. Can be preferably used. For example, gallium trichloride, tin tetrachloride, boron trichloride, germanium tetrachloride, antimony pentachloride, iron trichloride, aluminum trichloride, aluminum tribromide, tin tetrachloride, indium trichloride, boron trifluoride, triodor Boron bromide, zinc dichloride, zinc tetrachloride, antimony pentafluoride, antimony pentachloride, tantalum pentachloride, arsenic hexafluoride, arsenic pentafluoride, zirconium tetrachloride, vanadium tetrachloride, tin dichloride, copper dichloride or Titanium tetrachloride and the like. Among the above, from the viewpoint of high solubilizing ability and handling of organic pigments, sulfuric acid, nitric acid, toluenesulfonic acid,
Ethanesulfonic acid, propanesulfonic acid, trifluoroacetic acid, aluminum trichloride and aluminum tribromide are preferably used. Moreover, these acids can be used individually by 1 type or in combination of 2 or more types. The use ratio of the acid is not particularly limited, but it is preferably used in the range of 0.01 to 500 parts by mass with respect to 1 part by mass of the organic pigment, and when the acid and the organic solvent are mixed and used. It is preferable to use 1 part by mass or more with respect to 100 parts by mass of the organic solvent. Acid is 0.
It is preferable that the amount is 01 parts by mass or more, and the amount of the acid is 1 part by mass or more with respect to 100 parts by mass of the organic solvent because it is easy to completely dissolve the organic pigment together with the dispersant. Further, when the acid is 500 parts by mass or less with respect to the organic pigment,
From the viewpoint of tinting strength, it is possible to effectively prevent the concentration of the obtained organic pigment dispersion from becoming thin, and it is also preferable in terms of productivity because operations such as concentration can be omitted or simplified. .

When the acid and the organic solvent are mixed and used, in order to completely dissolve the acid, some water or a lower alcohol,
A solvent having a high solubility for an acid such as glycerin can be added to the organic solvent. This increases the solubility of the acid even in an organic solvent having a low acid solubility, and facilitates the dissolution of the organic pigment. The addition rate is less than 50% by mass with respect to the total amount of the solvent (the amount of the organic solvent used in the mixed solution of the acid and the organic solvent, and the amount of the water or the solvent added to completely dissolve the acid). Is preferable because the solubility of the organic pigment is excellent, and the addition rate of about 0.01 to 30% by mass is most effective. Specifically, water, methanol, ethanol, propyl alcohol, butyl alcohol, glycerin or the like can be added.

When an organic pigment is dissolved in an acid or a mixed solution of an acid and an organic solvent, a crystal growth inhibitor, an ultraviolet absorber, a resin additive, etc. may be added as necessary in addition to the organic pigment and the dispersant. You can Examples of the crystal growth inhibitor include phthalocyanine derivatives and quinacridone derivatives well known in the art. Examples thereof include phthalimidomethyl derivatives of phthalocyanines, sulfonic acid derivatives of phthalocyanines, N- (dialkylamino) methyl derivatives of phthalocyanines, and phthalocyanines. N- (dialkylaminoalkyl) sulfonic acid amide derivative, quinacridone phthalimidomethyl derivative, quinacridone sulfonic acid derivative, quinacridone N- (dialkylamino) methyl derivative, quinacridone N- (dialkylaminoalkyl) sulfonic acid amide derivative, etc. Is mentioned. As the ultraviolet absorber, metal oxides, aminobenzoate-based ultraviolet absorbers, salicylate-based ultraviolet absorbers,
UV absorbers such as benzophenone UV absorbers, benzotriazole UV absorbers, cinnamate UV absorbers, nickel chelate UV absorbers, hindered amine UV absorbers, urocanic acid UV absorbers and vitamin UV absorbers Can be mentioned. As the resin additive, anion-modified polyvinyl alcohol, cation-modified polyvinyl alcohol, polyurethane, carboxymethylcellulose, polyester, polyallylamine, polyvinylpyrrolidone, polyethyleneimine, polyaminesulfone, polyvinylamine, hydroxyethylcellulose, hydroxypropylcellulose, cationized starch, melamine. Examples thereof include resins and synthetic resins such as modified products thereof. Any of these crystal growth inhibitors, ultraviolet absorbers, and resin additives can be used alone or in combination of two or more.

The organic pigment and the dispersant thus obtained, which are dissolved in an acid or a mixed solution of an acid and an organic solvent (referred to as "pigment solution"), are mixed with water to form an organic pigment. The proportion of water used for precipitation is 0.1 to 1000 parts by mass, and further 1 to 50 parts by mass with respect to 1 part by mass of the pigment solution.
0 mass part is preferable. When the amount of water is 0.1 part by mass or more based on 1 part by mass of the pigment solution, the precipitation of the organic pigment is likely to proceed and the dispersion stability of the precipitated organic pigment is excellent, which is preferable. From the viewpoint of power, it is preferable that the concentration of the obtained organic pigment dispersion can be effectively prevented from becoming thin, and operations such as concentration can be omitted or simplified.

When the pigment solution and water are mixed, their temperature is in the range of -50 ° C to 100 ° C, and further -20.
It is preferable to adjust the temperature in the range of 50 ° C to 50 ° C. The temperature of the pigment solution and water at the time of mixing greatly affects the size of the precipitated organic pigment. Therefore, in order to obtain an organic pigment dispersion of nanometer order, the temperature of the pigment solution and water should be -50 ° C.
It is preferably in the range of -100 ° C. In order to ensure the fluidity of the solution when the pigment solution and water are mixed, the water to be mixed is mixed with ethylene glycol and propylene glycol.
It is possible to add a known freezing point depressant such as glycerol and glycerin.

Further, in order to obtain a nanometer-order pigment dispersion having a uniform size, it is preferable to mix the pigment solution and water as quickly as possible, such as an ultrasonic vibrator or a full-zone stirring blade. Any of the conventionally known devices used for stirring, mixing, and dispersing can be used.
Moreover, you may mix in the water which flows continuously. Further, in order to stably prepare the organic pigment dispersion, the acid and the dispersant may be added to the water mixed with the pigment solution.

The thus-obtained pigment dispersion can be subjected to concentration, removal of impurities, neutralization with alkali and subsequent desalting, etc. by a conventionally known method, and the pigment concentration can be adjusted according to need. It can be adjusted to pH.

The organic pigment dispersion prepared in the present invention can be preferably used as a colorant for an ink jet recording liquid. At this time, the concentration of the organic pigment dispersion in the inkjet recording liquid is preferably adjusted so that the pigment content is 2.0 to 10.0 parts by mass with respect to 100 parts by mass of the inkjet recording liquid from the viewpoint of coloring power. The ink jet recording liquid of the present invention includes a nozzle portion that is dried, the recording liquid is solidified,
A water-soluble organic solvent can be added for the purpose of adjusting viscosity. As the water-soluble organic solvent, for example, one having 1 to 4 carbon atoms
Alkyl alcohols (eg, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, t
ert-butyl alcohol, etc.), ketones or keto alcohols (eg acetone, diacetone alcohol, etc.),
Amides (eg dimethylformamide, dimethylacetamide etc.), acetone, diacetone alcohol etc.), ethers (eg tetrahydrofuran, dioxane etc.), polyalkylene glycols (eg polyethylene glycol, polypropylene glycol etc.), alkylene groups Alkylene glycols containing 2 to 6 carbon atoms (eg ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, hexylene glycol, diethylene glycol, etc.), alkyls such as polyhydric alcohols Ethers (eg ethylene glycol methyl ether, ethylene glycol ethyl ether, triethylene monomethyl ether, triethylene glycol monoethyl ether Le etc.), and further glycerine, polyhydric alcohols such as trimethylolpropane or alternatively N- methylpyrrolidone, 2-pyrrolidone, dimethylimidazolidinone and the like. The total amount of the water-soluble organic solvent in the ink (including the water-soluble organic solvent contained in the pigment solution as well as the water-soluble organic solvent added when the inkjet recording liquid is prepared) is the total amount of the ink (ink-jet recording liquid 100 2 to (parts by mass)
60 parts by mass, more preferably 5 to 25 parts by mass. Further, a surfactant may be added to the ink jet recording liquid of the present invention for the purpose of controlling the permeability to paper and improving the dispersion stability of the organic pigment dispersion. As the surface active agent, any conventionally known surface active agent such as a nonionic surface active agent, a cationic surface active agent, an amphoteric surface active agent, a fluorine type surface active agent, a silicon type surface active agent can be preferably used. The amount of the surfactant in the ink (including not only the surfactant added at the time of preparing the inkjet recording liquid but also the surfactant contained in the pigment solution) is 0 relative to the total amount of the ink (100 parts by mass of the inkjet recording liquid). 0.05 to 10 parts by mass, and as a more suitable range,
It is 0.1 to 5 parts by mass. The inkjet recording liquid of the present invention includes the above-mentioned organic pigment dispersion, a water-soluble organic solvent,
In addition to the surfactant, additives such as an antifungal agent, an antioxidant, and a pH adjuster may be appropriately mixed.

The organic pigment dispersion prepared in the present invention is an ink jet recording liquid, printing ink, toner, paint, writing ink, film coating material, ferroelectric printer, liquid developer, electrophotographic material. It can be used as a wide range of aqueous colorants such as plastic colorants, rubber colorants, and fiber colorants.

[0031]

EXAMPLES The present invention will be described more specifically by showing Examples and Comparative Examples below. In addition, "part" and "%" in the sentence
Unless otherwise indicated, the term "mass" is based on mass.

Example 1 Styrene-allylamine copolymer (base number 250, molecular weight 5000) as a dispersant
10 parts of C.I. I. Pigment B
Using 10 parts of phthalocyanine pigment of lue 15, these dispersants and pigments were dissolved in 80 parts of 98% sulfuric acid, and stirred at 25 ° C. for 2 hours in an air atmosphere. Then, add this solution to 0 ° C.
400 parts of water that had been cooled and kept warm was rapidly mixed using an ultrasonic homogenizer (manufactured by Branson) to obtain an aqueous dispersion of a phthalocyanine pigment.

Example 2 Styrene-allylamine copolymer as a dispersant (base number 250, molecular weight 5000)
5 parts and polyoxyethylene lauryl ether (PEG-
30) 3 parts and 2 parts of benzalkonium chloride, and C.I. I. Pigment Red 122 quinacridone pigment 8 parts and C.I. I. Pigment Violet
Using 2 parts of quinacridone pigment of t 19 and dissolving these dispersant and pigment in 80 parts of 98% sulfuric acid,
The mixture was stirred at 5 ° C for 2 hours. Then, this solution was rapidly mixed with 400 parts of water cooled and kept at 0 ° C. using an ultrasonic homogenizer (manufactured by Branson) to obtain a solid solution aqueous dispersion of the quinacridone pigment.

Example 3 Styrene-allylamine copolymer as a dispersant (base number 250, molecular weight 5000)
8 parts and polyoxyethylene lauryl ether (PEG-
30) 2 parts with C.I. I. Pigment
7 parts of isoindolinone pigment of Yellow 110 and C.I. I. Pigment Yellow 109 isoindolinone pigment (3 parts) was used to dissolve these dispersants and pigments in trifluoroacetic acid (80 parts), and the mixture was ice-cooled under a nitrogen atmosphere and stirred for 2 hours. Next, this solution was rapidly mixed with 400 parts of water cooled and kept at 0 ° C. using an ultrasonic homogenizer (manufactured by Branson), and trifluoroacetic acid was distilled under reduced pressure to give a solid solution of quinacridone pigment water. A dispersion was obtained.

Example 4 Styrene-allylamine copolymer as a dispersant (base number 250, molecular weight 5000)
8 parts and polyoxyethylene lauryl ether (PEG-
30) 2 parts with C.I. I. Pigmen
Using 10 parts of a phthalocyanine pigment of t Blue 15, these dispersants and pigments were dissolved in a mixed solution of 15 parts of aluminum trichloride and 65 parts of dimethyl sulfoxide.
This solution was stirred for 3 hours, then cooled to 0 ° C and kept warm with water 4.
A water dispersion of a phthalocyanine pigment that was solid-solution-dissolved was rapidly mixed with 00 parts.

Example 5 Styrene-allylamine copolymer as a dispersant (base number 250, molecular weight 5000)
5 parts and polyoxyethylene lauryl ether (PEG-
30) 5 parts and C.I. I. Pigmen
t Red 122, 8 parts quinacridone pigment and C.I. I.
Pigment Violet 19 quinacridone pigment 2 parts, nitric acid 10 parts and dimethylsulfoxide 70
These dispersants and pigments were dissolved in a part of the mixed solution and stirred at 25 ° C. for 2 hours in an air atmosphere. Then, add this solution to 0 ° C.
400 parts of water that had been cooled and kept warm was rapidly mixed using an ultrasonic homogenizer (manufactured by Branson) to obtain an aqueous dispersion of a quinacridone pigment which was solid-solved.

Comparative Example 1 C.I. I. Pigment B
10 parts of the phthalocyanine pigment of lue 15 was dissolved in 80 parts of 98% sulfuric acid, and the mixture was stirred at 25 ° C. for 2 hours in an air atmosphere. Next, this solution was rapidly mixed with 400 parts of water cooled and kept at 0 ° C. using an ultrasonic homogenizer (manufactured by Branson) to obtain a phthalocyanine pigment paste. After the paste was collected by filtration, it was thoroughly washed with water. Next, a styrene-allylamine copolymer (base number 25
0, a molecular weight of 5000), and 400 parts of water containing 2.5 parts of hydrochloric acid are mixed with the above paste, subjected to ultrasonic treatment, and then dispersed using a sand mill (Yasukawa Seisakusho),
An aqueous dispersion of phthalocyanine pigment was obtained.

Comparative Example 2 C.I. I. Pigment R
ed 122 8 parts quinacridone pigment and C.I. I. Pig
2 parts of quinacridone pigment of ment Violet 19 was dissolved in 80 parts of 98% sulfuric acid, and the mixture was allowed to stand at 25 ° C. for 2 hours in an air atmosphere.
Stir for hours. Next, this solution was rapidly mixed with 400 parts of water containing 10 parts of a styrene-allylamine copolymer (acid value 250, molecular weight 5000) and 2.5 parts of hydrochloric acid while cooling and maintaining the temperature at 0 ° C. to obtain a solid solution. An aqueous dispersion of the modified quinacridone pigment was obtained.

Table 1 collectively shows the measurement results of the average particle diameter (diameter) of the organic pigment dispersions in the respective water dispersions obtained in the above Examples and Comparative Examples. The organic pigment dispersions obtained in the examples had a small dispersed particle size, and were monodisperse and had a narrow particle size distribution, but the organic pigment dispersions obtained in Comparative Examples had a large dispersed particle size, It had only a wide diameter distribution. Incidentally, each dispersed particle size after dilution with ion-exchanged water,
Filter with a 1.0 μm membrane filter to obtain DLS-
The measurement is performed using 7000 (trade name, manufactured by Otsuka Electronics Co., Ltd.).

[0040]

[Table 1]

Next, each of the obtained aqueous dispersions was concentrated and purified by an ultrafiltration membrane to obtain an aqueous dispersion concentrated solution having a pigment content concentration of 20%, which was then mixed with the following to prepare an ink jet printer. A recording liquid for use was obtained. In addition, "Acetylenol E
“H” is a trade name of an ethylene oxide adduct of acetylene glycol manufactured by Kawaken Fine Chemicals. -25 parts of the aqueous dispersion concentrate-diethylene glycol 7.5 parts-glycerin 5 parts-trimethylol propane 5 parts-acetylenol EH 0.2 parts-water 57.3 parts A commercially available inkjet printer (Canon A color recording image was recorded on an OHP sheet and a copy sheet by using a trade name, BJF 870, manufactured by the company. Table 2 shows the results of evaluation of the image transparency based on the haze value of the OHP sheet and the color density of the image based on the following criteria based on the OD value of the solid print portion of the copy paper.

[Transparency Evaluation (OHP Sheet)] Commercial O
A solid patch image is printed on an HP sheet (trade name: CF-301, manufactured by Canon Inc.) using the above recording liquid, and the haze value of the printed portion is measured by a haze meter (trade name: direct reading haze meter, manufactured by Toyo Seiki). The following evaluation criteria were used. ◯: Haze value is less than 10, Δ: Haze value is 10 or more and less than 20, X: Haze value is 20 or more.

[Color Density Evaluation (OD Value)] A solid patch image was printed on the commercially available copy paper (trade name: PB paper, manufactured by Canon) using the above recording liquid, and left for 1 hour, and then the recording density was changed to Macbeth RD915. (Product name: manufactured by Macbeth Co., Ltd.) and used as the following evaluation criteria. ◯: The density was 1.25 or higher. Δ: The density of each color was 1.15 to 1.25. X: The density of each color was 1.15 or less.

[0044]

[Table 2]

In the recording liquid using the pigment dispersion of the example,
The projection of OHP was bright and vivid, but the projection of OHP was dark and sunk in the recording liquid using the pigment dispersion of the comparative example. In addition, the color density of a plain paper print is high in the recording liquid using the pigment dispersion of the example.
Although the D value was shown, the recording liquid using the pigment dispersion of the comparative example showed a low OD value.

[0046]

EFFECTS OF THE INVENTION According to the present invention, there is no need for treatment with a dispersing device for a long time, and it is possible to obtain nanometer-order particles having high dispersion stability and size uniformity that do not depend on the size of the primary particles of the starting pigment. A pigment dispersion having excellent transparency and a method for producing the same can be obtained. Further, an aqueous coloring liquid excellent in water resistance and light resistance, and also excellent in color developability and light transmittance, particularly an inkjet recording liquid was provided.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masafumi Hirose             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation (72) Inventor Akio Kashiwazaki             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2C056 EA13 FC01 FD20                 2H086 BA55 BA59                 4J037 AA30 CA05 CA08 CA18 CA19                       CA21 CB04 CB07 CB09 CB10                       CB11 CB15 CB16 CB19 CB21                       CC01 CC02 CC16 CC25 DD23                       DD24 EE28 EE33 EE43 FF02                       FF22 FF23 FF25                 4J039 AB01 AB07 AB08 AD03 AD10                       AD12 AD23 AE07 BA10 BA17                       BA18 BA19 BC05 BC06 BC07                       BC11 BC12 BC13 BC19 BC20                       BC29 BC32 BC33 BC50 BC51                       BC54 BE01 BE12 BE22 CA06                       EA35 EA38 EA44 GA24

Claims (12)

[Claims] 1. A dissolution step in which an organic pigment and a dispersant are dissolved in an acid or a mixed solution of an acid and an organic solvent, and the pigment solution obtained in the dissolution step is mixed with water to precipitate the organic pigment. And a precipitation step to allow the organic pigment dispersion to be produced. 2. The method according to claim 1, wherein the dispersant is a polymer compound or a surfactant having at least one selected from a cationic nitrogen atom, a hydroxyl group and an alkylene oxide in the molecule. 3. The method according to claim 1, wherein the solubility of the organic solvent in water is 5% by mass or more. 4. The method according to claim 1, wherein the acid is an organic protonic acid. 5. The organic protonic acid is one or more selected from alkyl sulfonic acids, alkyl carboxylic acids, halogenated alkyl sulfonic acids, halogenated alkyl carboxylic acids, aromatic carboxylic acids and aromatic sulfonic acids. Item 4. The method according to Item 4. 6. The method according to claim 1, wherein the acid is an inorganic protonic acid. 7. The inorganic protonic acid is selected from sulfuric acid, nitric acid, phosphoric acid, polyphosphoric acid, hydrochloric acid, perchloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid and chlorosulfonic acid. The method according to claim 6, which is one or more kinds. 8. The acid according to claim 1, which is a Lewis acid.
The method according to any one of 1. 9. The Lewis acid is aluminum, iron,
The method according to claim 8, which is one or more halides selected from copper, zinc, tin, gallium, boron, titanium, zirconium, indium, silicon, germanium, antimony, arsenic, tungsten, tantalum, zirconium and vanadium. 10. An organic pigment dispersion produced by the method according to any one of claims 1 to 9. 11. An aqueous coloring liquid containing the organic pigment dispersion according to claim 10. 12. An ink jet recording liquid containing the organic pigment dispersion according to claim 10.