JP2009292999A - Manufacturing process of dispersion of organic pigment fine particles, and ink for inkjet recording and paint prepared by the process - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide: a manufacturing process of a low-viscosity dispersion containing organic pigment fine particles having small particle sizes and a narrow particle size distribution; a manufacturing process of an organic pigment fine particle dispersion which reduces the amount of a dispersant for dispersing organic pigment fine particles, enables use of dispersants unstable to high concentration alkalis, and makes the kinds of applicable dispersants abundant; and ink for inkjet recording and paint using the organic pigment particles prepared by the processes. <P>SOLUTION: The manufacturing process of the organic pigment fine particle dispersion includes a step where an organic pigment solution, in which an organic pigment is dissolved in an organic solvent, and a surfactant solution, in which a surfactant with a molecular weight of <1,000 is dissolved in an organic solvent, are joined together in a flow path to obtain a joint flow, and the joint flow further comes together with an aqueous medium in the flow path to generate the fine particles of the organic pigment. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing an organic pigment fine particle dispersion, and an ink and ink for ink jet recording using the organic pigment fine particles obtained thereby.

  Pigments show vivid colors and high tinting strength and are widely used in many fields. For example, paints, printing inks, electrophotographic toners, inkjet inks, color filters, and the like can be used as the application. Among them, color filters and inkjet inks are particularly important applications that require high performance.

  As for color filters, in order to realize downsizing and increase in pixels in image-related devices such as liquid crystal display devices, CCD sensors, and digital cameras, in recent years, there has been a strong demand for thinner layers. And in order to make a color filter thin, it is indispensable to make the pigment used there fine. In addition, development of uniform and fine pigment fine particles is also required for increasing the contrast of color filters. In other words, the development of fine, uniform and stable pigment particles is the key to improving the performance of image-related equipment.

  On the other hand, when it comes to ink-jet inks, dyes have conventionally been used for the coloring materials. However, dyes have low water resistance and light resistance, and pigments have been used to improve them. Attempts have been made to use inkjet technology not only for printing purposes but also for the production of various precision members. For example, it is expected to replace the conventional technology such as lithography with the production of the color filter and increase the degree of freedom of design and greatly improve the productivity. However, there are still no pigment fine particles and inks that are suitable and adequately meet the requirements.

  From such a background, it is required to make the pigment finer to, for example, a diameter of several tens of nanometers and to control the particle diameter so as to approach monodispersion. It is generally difficult to obtain such particles by a general pulverization method (breakdown method). This is because it takes a lot of time and energy to pulverize the particles to nanometer size by this method, the production efficiency is low, and usable substances are limited. Further, it is known that when too strong energy is applied in the pulverization method, an adverse effect called overdispersion, for example, a phenomenon such as thickening due to reaggregation occurs.

On the other hand, obtaining pigment fine particles by a build-up method has been studied as a method not based on pulverization. For example, a crude product of an organic pigment is dissolved in an organic solvent using an alkali to form a solution, and this solution is mixed with water in the presence of a dispersant or a surfactant in a vessel such as a flask to form a fine particle dispersion. Is disclosed (see Patent Documents 1 and 2). By this technique, a dispersion of pigment fine particles can be obtained without going through a pulverizing operation. Further, using a microreactor, a polymerizable compound is contained in at least one of an alkaline or acidic solution in which an organic pigment is dissolved and an aqueous medium, and both are mixed to precipitate pigment fine particles, and then the polymerization is performed. A method for producing a pigment dispersion for polymerizing a functional compound has been developed. Thereby, it is supposed that the dispersion liquid with a small particle diameter and favorable monodispersibility is obtained (refer patent document 3).
In addition, at least three kinds of a solution of an organic material dissolved in a good solvent, a solvent that is compatible with the good solvent and becomes a poor solvent for the organic material, and a solution containing a polymer dispersant are used simultaneously or There is a method for producing organic particles that are sequentially mixed and the organic material is produced as particles in the mixed solution (see Patent Document 4). However, the liquid mixing here is stirring and mixing in a tank, and it is difficult to precisely control the fine particle precipitation conditions.

  However, in the above Patent Documents 1 to 4, all of them are dissolved in either an organic solvent solution or an aqueous medium in which an organic pigment is dissolved. Therefore, it is not possible to freely select a solvent for dissolving the dispersant or the like. That is, since the solvent is selected in consideration of the solubility of the organic pigment, the precipitation of the fine particles, and the like, it is not necessarily a preferable solvent type in terms of the solubility of the dispersant and the like. For example, when an organic pigment solution is dissolved in the presence of an alkali, it is difficult to use a compound having a dispersant unstable to the alkali. In particular, under conditions where a strong base such as a metal hydroxide or a metal alkoxide is used as the alkali, the dispersant or the like may be decomposed or modified. On the other hand, in the method of dissolving a dispersant in an aqueous medium, a commonly usable dispersant is limited to those having solubility in water. Then, pigment fine particles are precipitated from a state in which the pigment and the dispersant do not coexist, and are mixed and contacted with the dispersant in the aqueous medium. In principle, this is a disadvantageous method in terms of imparting dispersibility. As a result, the particle size may become uncontrollable and coarse, or a large amount of dispersant may be required.

  On the other hand, there is a method for producing pigment fine particles in which a pigment solution and a polymer dispersant solution are separately prepared, and a continuous operation of a mixing process of both liquids and a mixing process of the mixed liquid and water as a poor solvent is performed with a microreactor device. It is disclosed (see Patent Document 5). However, since this method uses a block copolymer, which is a polymer compound, as a dispersant, a large amount of dispersant is required. In addition, the use of a dispersant that is unstable with respect to alkali or the like is not described.

JP 2003-113341 A JP 2004-43776 A JP 2007-39643 A International Publication WO / 2007/013599 Pamphlet JP 2006-104448 A

  An object of the present invention is to provide an efficient method for producing a dispersion containing organic pigment fine particles having a small particle size and a narrow particle size distribution, and having both dispersion stability and low viscosity. In addition, the amount of the surfactant that disperses the organic pigment fine particles can be reduced. Further, even if it is unstable to a high concentration of alkali, it can be used. It is an object of the present invention to provide a method for producing an organic pigment fine particle dispersion that can be enriched, and an ink and ink for ink jet recording using the organic pigment fine particles obtained thereby.

The above object of the present invention has been achieved by the following means.
(1) An organic pigment solution in which an organic pigment is dissolved in an organic solvent and a surfactant solution in which a surfactant having a molecular weight of less than 1,000 is dissolved in an organic solvent are combined in a flow path to form a combined solution, A method for producing an organic pigment fine particle dispersion, comprising the step of causing the combined liquid and the aqueous medium to further flow and merge in a flow path to produce fine particles of the organic pigment.
(2) The method for producing an organic pigment dispersion according to (1), wherein the organic pigment solution is a solution obtained by dissolving the organic pigment in the presence of an alkali.
(3) The step of joining the combined solution of the organic pigment solution and the surfactant solution and the aqueous medium is performed in a flow path having an equivalent diameter of 2 mm or less (1) or (2) The manufacturing method of the organic pigment dispersion as described in any one of.
(4) The step of joining the organic pigment solution and the surfactant solution and the step of joining the joined solution and the aqueous medium are both performed in a flow path having an equivalent diameter of 2 mm or less (1) The manufacturing method of the organic pigment dispersion of any one of (3)-(3).
(5) The organic pigment solution and the surfactant solution are layered after the organic pigment solution and the surfactant solution are merged in the flow channel until the merged solution and the aqueous medium are merged. It distribute | circulates in a flow state, The manufacturing method of the organic pigment dispersion of any one of (1)-(4) characterized by the above-mentioned.
(6) The combined solution of the organic pigment solution and the surfactant solution flowing in a laminar flow state and the aqueous medium are combined between the organic pigment solution and the aqueous medium. (5) The method for producing an organic pigment dispersion as described in (5) above.
(7) The mass of the surfactant in the dispersion is 0.5 times or less with respect to the mass of the organic pigment, according to any one of (1) to (6), A method for producing an organic pigment dispersion.
(8) The method for producing an organic pigment dispersion according to any one of (1) to (7), wherein a compound decomposable with respect to alkali is used as the surfactant.
(9) The method for producing an organic pigment dispersion according to any one of (1) to (8), wherein the organic pigment fine particles have a volume average particle size (Mv) of 10 nm to 50 nm.
(10) An ink for inkjet recording containing the organic pigment fine particles in a dispersion obtained by the production method according to any one of (1) to (9).
(11) A paint containing the organic pigment fine particles in a dispersion obtained by the production method according to any one of (1) to (9).

  According to the production method of the present invention, it is possible to obtain a dispersion containing organic pigment fine particles having a small particle size and a narrow particle size distribution with a small amount of a surfactant, and the dispersion stabilization and low viscosity of the dispersion. Can be realized at the same time. Further, according to the present invention, the range of types of surfactants that can be used is expanded, for example, the use of unstable dispersants that are modified or decomposed by coexisting with a high concentration of alkali in a pigment solution. enable. Further, according to the production method of the present invention, the organic pigment fine particles having the above-mentioned excellent characteristics can be obtained efficiently and with high purity, and the ink and ink for ink-jet recording using this have good dischargeability or paintability, It has a bright and brilliant color.

  Hereinafter, the present invention will be described in detail based on preferred embodiments thereof.

  The method for producing an organic pigment dispersion according to the present invention distributes an organic pigment solution in which an organic pigment is dissolved in an organic solvent and a surfactant solution in which a surfactant having a molecular weight of less than 1000 is dissolved in the organic solvent in the flow path. And the liquid and the aqueous medium are joined together while being circulated in the flow path to produce the fine particles of the organic pigment.

  The volume average particle size of the organic pigment fine particles obtained by the production method of the present invention is preferably 100 nm or less, more preferably 70 nm or less, and particularly preferably 10 nm or more and 50 nm or less. For monodispersity, the value (Mv / Mn) obtained by dividing the volume average particle size (Mv), which is an index thereof, by the number average particle size (Mn) is preferably 1.8 or less. More preferably, it is 1.5 or less. In the present invention, the average particle diameter (Mv, Mn) and monodispersity (Mv / Mn) of the pigment fine particles are determined using Nanotrac UPA-EX150 (trade name) manufactured by Nikkiso Co., Ltd. unless otherwise specified. The value measured at room temperature (around 25 ° C.) after diluting to a pigment concentration of 0.2 mass% with distilled water.

  The target “dispersion” in the method of the present invention refers to a composition in which fine particles are dispersed in a medium, and the form thereof is not particularly limited. A liquid composition (dispersion), a paste-like composition, And a solid composition.

  In the organic pigment fine particle dispersion obtained by the production method of the present invention, the content of the organic pigment fine particles is not particularly limited, but is preferably 0.1% by mass to 50% by mass in the dispersion, and 0.5% by mass. More preferably, it is -25 mass%.

  The organic pigment used in the present invention is not limited in hue, and may be a magenta pigment, a yellow pigment, or a cyan pigment. Specifically, for example, perylene, perinone, quinacridone, quinacridonequinone, anthraquinone, anthanthrone, benzimidazolone, disazo condensation, disazo, azo, indanthrone, phthalocyanine, triarylcarbonium, dioxazine, aminoanthraquinone, diketopyrrolopyrrole, Magenta pigments such as thioindigo, isoindoline, isoindolinone, pyranthrone or isoviolanthrone pigments or mixtures thereof, yellow pigments, or cyan pigments.

  More specifically, for example, C.I. I. Pigment red 190 (C.I. No. 71140), C.I. I. Pigment red 224 (C.I. No. 71127), C.I. I. Perylene pigments such as CI Pigment Violet 29 (C.I. No. 71129); I. Pigment orange 43 (C.I. No. 71105), or C.I. I. Perinone pigments such as CI Pigment Red 194 (C.I. No. 71100); I. Pigment violet 19 (C.I. No. 73900), C.I. I. Pigment violet 42, C.I. I. Pigment red 122 (C.I. No. 73915), C.I. I. Pigment red 192, C.I. I. Pigment red 202 (C.I. No. 73907), C.I. I. Pigment Red 207 (C.I. No. 73900, 73906) or C.I. I. Pigment Red 209 (C.I. No. 73905), a quinacridone pigment, C.I. I. Pigment red 206 (C.I. No. 73900/73920), C.I. I. Pigment orange 48 (C.I. No. 73900/73920), or C.I. I. Quinacridone quinone pigments such as CI Pigment Orange 49 (C.I. No. 73900/73920); I. Anthraquinone pigments such as CI Pigment Yellow 147 (C.I. No. 60645); I. Anthanthrone pigments such as CI Pigment Red 168 (C.I. No. 59300); I. Pigment brown 25 (C.I. No. 12510), C.I. I. Pigment violet 32 (C.I. No. 12517), C.I. I. Pigment yellow 180 (C.I. No. 21290), C.I. I. Pigment yellow 181 (C.I. No. 11777), C.I. I. Pigment orange 62 (C.I. No. 11775), or C.I. I. Benzimidazolone pigments such as CI Pigment Red 185 (C.I. No. 12516); I. Pigment yellow 93 (C.I. No. 20710), C.I. I. Pigment yellow 94 (C.I. No. 20038), C.I. I. Pigment yellow 95 (C.I. No. 20034), C.I. I. Pigment yellow 128 (C.I. No. 20037), C.I. I. Pigment yellow 166 (C.I. No. 20035), C.I. I. Pigment orange 34 (C.I. No. 21115), C.I. I. Pigment orange 13 (C.I. No. 21110), C.I. I. Pigment orange 31 (C.I. No. 20050), C.I. I. Pigment red 144 (C.I. No. 20735), C.I. I. Pigment red 166 (C.I. No. 20730), C.I. I. Pigment red 220 (C.I. No. 20055), C.I. I. Pigment red 221 (C.I. No. 20065), C.I. I. Pigment red 242 (C.I. No. 20067), C.I. I. Pigment red 248, C.I. I. Pigment red 262, or C.I. I. Disazo condensation pigments such as CI Pigment Brown 23 (C.I. No. 20060); I. Pigment yellow 13 (C.I. No. 21100), C.I. I. Pigment yellow 83 (C.I. No. 21108), or C.I. I. Disazo pigments such as CI Pigment Yellow 188 (C.I. No. 21094); I. Pigment red 187 (C.I. No. 12486), C.I. I. Pigment red 170 (C.I. No. 12475), C.I. I. Pigment yellow 74 (C.I. No. 11714), C.I. I. Pigment red 48 (C.I. No. 15865), C.I. I. Pigment red 53 (C.I. No. 15585), C.I. I. Pigment orange 64 (C.I. No. 12760), or C.I. I. Azo pigments such as C.I. Pigment Red 247 (C.I. No. 15915), C.I. I. Indanthrone pigments such as CI Pigment Blue 60 (C.I. No. 69800); I. Pigment green 7 (C.I. No. 74260), C.I. I. Pigment Green 36 (C.I. No. 74265), Pigment Green 37 (C.I. No. 74255), Pigment Blue 16 (C.I. No. 74100), C.I. I. Phthalocyanine pigments such as CI Pigment Blue 75 (C.I. No. 74160: 2) or 15 (C.I. No. 74160); I. Pigment blue 56 (C.I. No. 42800), or C.I. I. Triarylcarbonium pigments such as CI Pigment Blue 61 (C.I. No. 42765: 1); I. Pigment violet 23 (C.I. No. 51319) or C.I. I. Dioxazine pigments such as CI Pigment Violet 37 (C.I. No. 51345); I. Aminoanthraquinone pigments such as CI Pigment Red 177 (C.I. No. 65300); I. Pigment red 254 (C.I. No. 56110), C.I. I. Pigment Red 255 (C.I. No. 561050), C.I. I. Pigment red 264, C.I. I. Pigment red 272 (C.I. No. 561150), C.I. I. Pigment orange 71, or C.I. I. Diketopyrrolopyrrole pigments such as C.I. Pigment Orange 73; I. Thioindigo pigments such as CI Pigment Red 88 (C.I. No. 7313); I. Pigment yellow 139 (C.I. No. 56298), C.I. I. Pigment Orange 66 (C.I. No. 48210) and the like, isoindoline pigments such as C.I. I. Pigment yellow 109 (C.I. No. 56284), or C.I. I. Pigment Orange 61 (C.I. No. 11295) and other isoindolinone pigments, C.I. I. Pigment Orange 40 (C.I. No. 59700), or C.I. I. Pyranthrone pigments such as CI Pigment Red 216 (C.I. No. 59710), or C.I. I. It is an isoviolanthrone pigment such as CI Pigment Violet 31 (60010).

  Preferred pigments are quinacridone, diketopyrrolopyrrole, disazo condensation pigments, or phthalocyanine pigments, and particularly preferred are quinacridone, disazo condensation pigments, or phthalocyanine pigments.

  In the method for producing an organic pigment dispersion of the present invention, the organic pigment solution is preferably introduced into the flow path as a uniformly dissolved solution. If a liquid containing pigment particles or solid alkali or salt is added, the particle size may increase or the pigment particles may have a wide particle distribution, which may block the flow path. In the present invention, “uniformly dissolved” refers to a state in which turbidity is hardly observed when observed under visible light, and the solution passes through a solution obtained through a microfilter of 1 μm or less, or a 1 μm filter. In this case, it means a solution obtained by uniformly dissolving a solution that does not contain a substance to be filtered.

  The organic solvent for dissolving the organic pigment used in preparing the organic pigment solution (hereinafter, the organic solvent used for dissolving the organic pigment may be referred to as “good solvent”) is not particularly limited. , Propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, acetylene glycol derivatives, glycerin, trimethylolpropane, etc. Polyhydric alcohol compounds such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, or triethylene glycol monoethyl (or butyl) ether Kill ether compound solvent, polyether compound solvent such as ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether (diglyme), or triethylene glycol dimethyl ether (triglyme), dimethylformamide, dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone Amide compound solvents such as 1,3-dimethyl-2-imidazolidinone, urea, or tetramethylurea, sulfur-containing compound solvents such as sulfolane, dimethyl sulfoxide, or 3-sulfolene, polyfunctionality such as diacetone alcohol, diethanolamine, etc. Compound solvent, carboxylic acid compound solvent such as acetic acid, maleic acid, docosahexaenoic acid, trichloroacetic acid or trifluoroacetic acid, methanesulfonic acid, Ku is a sulfonic acid compound solvent such as trifluoroacetic acid. Two or more of these solvents may be mixed and used. In addition, an acid, an alkali, or the like may be added as appropriate for dissolution. The amount of the good solvent used is an amount capable of uniformly dissolving the organic pigment, and is not particularly limited, but is preferably 10 to 500 times, and preferably 20 to 100 times the mass ratio of the organic pigment. Amount. Among these, as the good solvent, an amide compound solvent or a sulfur-containing compound solvent is preferable, a sulfur-containing compound solvent is more preferable, and dimethyl sulfoxide (DMSO) is particularly preferable.

  In order to dissolve the organic pigment, it is preferable to add an alkali or an acid to the good solvent. Whether it dissolves acidic or alkaline can be selected depending on which condition the pigment dissolves more uniformly. In general, in the case of a pigment having an alkaline and dissociable group in the molecule, it is possible to use alkalinity. . For example, quinacridone, diketopyrrolopyrrole, and disazo condensation pigments are alkaline, and phthalocyanine pigments are acidic and can be more uniformly dissolved. In this production method, it is preferable to add an alkali as much as possible and dissolve it.

The base used in the case of alkaline dissolution is not particularly limited, and examples thereof include inorganic bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, and barium hydroxide, or trialkylamine, diazabicycloundecene. (DBU), organic bases such as metal alkoxides (NaOCH ₃ , KOC ₂ H ₅ ), tetraalkylammonium alkoxides (such as tetramethylammonium methoxide), tetraalkylammonium hydroxides (such as tetramethylammonium hydroxide), etc. It is preferable that at least one selected from sodium hydroxide, potassium hydroxide, metal alkoxide, tetraalkylammonium alkoxide, and tetraalkylammonium hydroxide.

  The amount of the base used is an amount capable of uniformly dissolving the pigment, and is not particularly limited, but in the case of an inorganic base, it is preferably 1.0 to 30 molar equivalents relative to the pigment, more preferably 2. It is 0-25 molar equivalent, Most preferably, it is 3.0-20 molar equivalent. In the case of an organic base, it is preferably 0.4 to 100 molar equivalents, more preferably 1.0 to 20 molar equivalents, and further preferably 1.0 to 10 molar equivalents with respect to the pigment. The concentration of the added base with respect to the pigment solution is not particularly limited, but is preferably 0.01 mol / L to 10 mol / L, and more preferably 0.1 mol / L to 2 mol / L.

  Examples of the acid used for the acid dissolution include inorganic acids such as sulfuric acid, hydrochloric acid, and phosphoric acid, and organic acids such as acetic acid, trifluoroacetic acid, oxalic acid, methanesulfonic acid, and trifluoromethanesulfonic acid. However, it is preferably an inorganic acid, more preferably sulfuric acid.

  The amount of the acid used is an amount capable of uniformly dissolving the pigment, and is not particularly limited, but is often used in an excessive amount as compared with the base. Regardless of the inorganic acid or organic acid, it is preferably 3 to 500 molar equivalents, more preferably 10 to 500 molar equivalents, and particularly preferably 10 to 100 molar equivalents with respect to the pigment.

  In the production method of the present invention, the concentration of the organic pigment in the pigment solution is not particularly limited, but is preferably 0.5 to 20% by mass, and more preferably 1.0 to 10% by mass.

  In the present invention, the aqueous medium serves as a poor solvent for the pigment and refers to water alone or a mixed solvent of water and an organic solvent soluble in water. The organic solvent used in the aqueous medium is not sufficient to obtain the viscosity necessary to circulate in the flow path, for example, when water alone is insufficient to uniformly dissolve the pigment and the surfactant. In such a case, it is preferably used when necessary for forming a laminar flow. The aqueous medium may contain water-soluble inorganic salts, acids, alkalis and the like. The pH is preferably 10 or less, more preferably 3 to 9, and particularly preferably 6 to 8. The organic solvent contained in the aqueous medium is not limited, and examples thereof include alcohol solvents such as methanol, isopropyl alcohol, ethylene glycol, propylene glycol, diethylene glycol, and glycerin, and lower monoalkyl ether solvents of polyhydric alcohols such as ethylene glycol monomethyl ether. Polyether solvents such as ethylene glycol dimethyl ether (monoglyme), amide solvents such as dimethylformamide, dimethylacetamide, 2-pyrrolidone and N-methyl-2-pyrrolidone, ketones such as acetone and 2-butanone, sulfolane, dimethyl Examples thereof include sulfoxide and acetic acid, and alcohol solvents and dimethyl sulfoxide are preferable. Two or more of these solvents may be mixed and used.

  In the method for producing an organic pigment dispersion of the present invention, a solution in which one or more surfactants having a molecular weight of less than 1,000 are dissolved is used. The type of the surfactant is not particularly limited, and any of anionic, cationic and nonionic surfactants can be used. In the present invention, it is preferable to use one or more anionic surfactants. The surfactant has the action of (1) quickly adsorbing to the surface of the deposited pigment to form fine pigment particles, and (2) preventing these particles from aggregating again. Compared with a polymer dispersant or the like, a low molecular surfactant has high mobility and is suitable for a build-up synthesis method from the viewpoint of the speed of adsorption. In the production method of the present invention, a polymer dispersant or a pigment dispersant different from the surfactant may be used in appropriate combination. The dispersant used for dispersing the pigment is described in detail on pages 29 to 46 of “Pigment dispersion stabilization and surface treatment technology / evaluation” (Chemical Information Association, issued in December 2001).

Examples of the anionic surfactant include dialkyl sulfosuccinate, N-acyl-N-alkyl taurate, fatty acid salt, alkyl sulfate ester salt, alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkyl phosphate ester salt, and naphthalene sulfone. Examples include acid formalin condensate and polyoxyethylene alkyl sulfate ester salt.
Of these, dialkylsulfosuccinate having an ester structure (for example, di (2-ethylhexyl) sulfosuccinate sodium) is particularly preferable. These anionic surfactants can be used alone or in combination of two or more.

  Cationic surfactants include quaternary ammonium salts, alkoxylated polyamines, aliphatic amine polyglycol ethers, aliphatic amines, diamines and polyamines derived from aliphatic amines and fatty alcohols, imidazolines derived from fatty acids and Salts of these cationic substances are included. These cationic surfactants can be used alone or in combination of two or more.

  The amphoteric surfactant is a surfactant having both an anion group part in the molecule of the anionic surfactant and a cation group part in the molecule of the cationic surfactant.

  Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl aryl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin fatty acid ester, etc. be able to. Of these, polyoxyethylene alkylaryl ether is preferable. These nonionic surfactants can be used alone or in combination of two or more.

  In the present invention, it is preferable to use an anionic surfactant as the surfactant, and it is more preferable to use a dialkylsulfosuccinate, an N-acyl-N-alkyltaurine salt, a fatty acid salt, and an alkyl sulfate ester salt. preferable. The molecular weight (mass average molecular weight in the case of a mixture) of the surfactant is less than 1000 as described above, but is preferably 100 or more and less than 1000, and more preferably 200 or more and less than 800.

  In the production method of the present invention, a compound that can be hydrolyzed by the action of an alkali can be suitably used as the surfactant. It is preferable that the surfactant is contained in the surfactant solution and not contained in the pigment solution because it can be exhibited without impairing the dispersing action of the surfactant. In particular, surfactants having an ester group such as a dialkylsulfosuccinate are substantially used for the production of build-up pigment particles including a step of dissolving a pigment in an alkali, despite being advantageous in terms of cost. However, it can be used according to the method of the present invention.

A polymer dispersant may be used in combination with the surfactant. The polymer dispersant may be added to any of the pigment solution, the surfactant solution, and the aqueous medium, or may be added to the dispersion after forming the pigment particles. Specific examples of the polymer dispersant that can be used in combination with the surfactant include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyethylene glycol, polypropylene glycol, polyacrylamide, vinyl alcohol-vinyl acetate. Copolymer, polyvinyl alcohol-partial formalized product, polyvinyl alcohol-partially butylated product, vinylpyrrolidone-vinyl acetate copolymer, polyethylene oxide / propylene oxide block copolymer, polyacrylate, polyvinyl sulfate, poly (4- Vinylpyridine) salt, polyamide, polyallylamine salt, condensed naphthalene sulfonate, styrene-acrylate copolymer, styrene-methacrylate copolymer, acrylic acid ester Ru-acrylate copolymer, acrylate-methacrylate copolymer, methacrylate-acrylate copolymer, methacrylate-methacrylate copolymer, styrene-itaconate copolymer Itaconic acid ester-itaconate copolymer, vinylnaphthalene-acrylate copolymer, vinylnaphthalene-methacrylate copolymer, vinylnaphthalene-itaconate copolymer, cellulose derivative, starch derivative, etc. It is done. In addition, natural polymers such as alginate, gelatin, albumin, casein, gum arabic, tonganto gum and lignin sulfonate can also be used.
However, it is preferable not to use a polymer dispersant because it increases the amount of dispersant used.
In the present invention, the mass average molecular weight of the polymer dispersant is 1,000 to 1,000,000, preferably 3000 to 300,000, and more preferably 10,000 to 200,000. In the present invention, the molecular weight of the polymer compound refers to a polystyrene-reduced mass average molecular weight determined by gel permeation chromatography (carrier: tetrahydrofuran).

  A pigment dispersant may be used in combination with the surfactant. The pigment dispersant may be added to any of the pigment solution, the surfactant solution, and the aqueous medium, or may be added to the dispersion liquid after forming the pigment particles. The pigment dispersant is defined as a pigment dispersant which is derived from an organic pigment as a parent substance and is produced by chemically modifying the parent structure. For example, sugar-containing pigment dispersants, piperidyl-containing pigment dispersants, naphthalene or perylene-derived pigment dispersants, pigment dispersants having functional groups linked to the pigment parent structure through methylene groups, and polymer-modified pigment parents. Examples include a structure, a pigment dispersant having a sulfonic acid group, a pigment dispersant having a sulfonamide group, a pigment dispersant having an ether group, or a pigment dispersant having a carboxylic acid group, a carboxylic ester group, or a carboxamide group.

  In the surfactant solution, the solvent for dissolving the surfactant is preferably a medium containing an organic solvent as a main component, and more preferably a water-soluble organic solvent as a main component. The organic solvent for the surfactant solution is not particularly limited, and examples thereof include dimethyl sulfoxide, N, N-dimethylformamide, alcohols (preferably having a carbon number of 4 or less, such as methanol, ethanol), acetone, and tetrahydrofuran. Dimethyl sulfoxide, N, N-dimethylformamide and N-methylpyrrolidone are preferred.

  In the production method of the present invention, it is preferable that the surfactant solution does not contain an alkali. The concentration of the surfactant in the surfactant solution is not particularly limited, but the mass of the surfactant in the dispersion obtained by the production method of the present invention is 0.5 times or less with respect to the mass of the organic pigment. It is preferable to make it become 0.1-0.5 times, and 0.2-0.5 times is more preferable. The specific surfactant concentration of the surfactant solution can be, for example, 5 to 50% by mass.

  Although the above surfactant may be contained in the pigment solution and the aqueous medium, it is preferable not to contain the surfactant because a strong base or the like is added to the pigment solution as described above. A pigment solution containing a dispersant or a surfactant that is difficult to modify even in the strong alkaline environment, and a surfactant solution containing other surfactants, and a plurality of dispersants depending on the characteristics and restrictions as appropriate Or a surfactant may be used in combination.

  In the present invention, after obtaining a fine pigment particle dispersion, a polymerizable compound may be produced by polymerizing a polymerizable compound in the dispersion. This method can be expected to improve the dispersion stability and long-term storage stability by uniformly covering the pigment fine particles with a polymer. The polymerizable compound can be either water-soluble or hydrophobic. The polymerizable compound may be contained in any of a pigment solution, a dispersant solution, and an aqueous medium, and may be added after producing pigment fine particles.

  As a method for obtaining a polymer in the dispersion, it is preferable to radically polymerize a compound having a carbon double bond (C = C). Specific examples of the polymerizable compound include (meth) acrylic acid esters (for example, methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate), vinyl aromatic monomers (for example, styrene, o- Methylstyrene), vinyl esters (vinyl acetate, vinyl propionate, vinyl benzoate, etc., and derivatives thereof), N-vinylamides (for example, N-vinylpyrrolidone), (meth) acrylic acid amides, alkyl-substituted (meth) Acrylamides, methacrylamides, N-substituted maleimides, vinyl ethers (eg, vinyl methyl ether, vinyl ethyl ether), maleic anhydride, (meth) acrylonitrile, methyl vinyl ketone, and the like can be used. Among these, N-vinylpyrrolidone that produces polyvinylpyrrolidone effective as a polymer dispersant is particularly preferably used. In addition, a polyfunctional polymerizable compound can be used to more firmly cover the particles by crosslinking, and specific examples include ethylene glycol diacrylate, divinylbenzene, divinyl ethers, and the like.

  Among the polymerizable compounds, those in which the molecules have a hydrophilicity / hydrophobic function separated are called polymerizable surfactants, reactive surfactants, or reactive emulsifiers. It can use preferably for a manufacturing method. For example, α, β-ethylenically unsaturated group such as vinyl group, allyl group, propenyl group, (meth) acryloyl group and ion dissociable group such as sulfonic acid group or salt thereof, and hydrophilic group such as alkyleneoxy group The thing which has is mentioned. These are generally used for emulsion polymerization and are anionic or nonionic surfactants having at least one unsaturated bond capable of radical polymerization in the molecule.

  In the method for producing an organic pigment dispersion of the present invention, the polymerizable surfactant may be used alone, in combination with a different one, or with a polymerizable compound other than the polymerizable surfactant. Preferable polymerizable surfactants include, for example, Kao Corporation, Sanyo Chemical Co., Ltd., Daiichi Kogyo Seiyaku Co., Ltd., Asahi Denka Kogyo Co., Ltd., Nippon Emulsifier Co., Ltd., Nippon Oil & Fats. Examples include those commercially available from companies such as “State-of-the-art technology of fine particles / powder, Chapter 1, 3 Fine particle design using reactive emulsifier, pp23-31”, 2000 CMC Co., Ltd. And the like.

  Specific examples of the polymerizable surfactant are described below, but the present invention is not limited thereto.

  The polymerization method of the polymerizable compound used in the method for producing the organic pigment dispersion of the present invention is not particularly limited as long as it can be polymerized in the organic pigment dispersion, but polymerization is performed by generating radicals using a polymerization initiator. The method of making it preferable is. Although there are various triggers for initiating polymerization, it is preferable to use heat, light, ultrasonic waves, microwaves, or the like. As the polymerization initiator, water-soluble or oil-soluble persulfates, peroxides, azo compounds, and the like can be used. Specifically, ammonium persulfate, potassium persulfate, sodium persulfate, hydrogen peroxide, t-butyl hydroperoxide, 2,2′-azobisisobutyro and tolyl, 2,2′-azobis (2-amidino (Propane) dihydrochloride, 2,2′-azobis (2-N-benzylamidinopropane) dihydrochloride, 2,2′-azobis [2-N- (2-hydroxyethyl) amidinopropane] dihydrochloride, etc. For example, the homepage (www.wako-chem.co.jp) of Wako Pure Chemical Industries, Ltd. has various water-soluble azo polymerization initiators, oil-soluble azo polymerization initiators, and polymer azo polymerizations. Initiators are described and available with a 10 hour half-life temperature and its structural formula. Although the addition amount of a polymerization initiator is not specifically limited, It is 0.1-30 weight% with respect to all the monomer components, More preferably, it is 1-20 weight%, Most preferably, it is 2-10 weight%.

  The timing for performing the polymerization step is not particularly limited, and can be appropriately selected to be completed in the flow channel after obtaining the pigment fine particles, performed in the collected dispersion liquid, performed after purification or after concentration, etc. Since it is simple and the polymerization conditions can be made constant, it is easy to obtain a polymer having a uniform molecular weight and the like.

  The content of the polymerizable compound is in the range of 0.1 to 1000 parts by mass with respect to 100 parts by mass of the organic pigment in order to further improve the uniform dispersibility and temporal stability (storage stability) of the organic fine particles. It is preferably in the range of 1 to 500 parts by mass, particularly preferably in the range of 10 to 250 parts by mass. If this amount is too small, the dispersion stability of the organic pigment fine particles after the polymer treatment may not be improved. The content of the surfactant in addition to the polymerizable compound is preferably such that the total amount of both is in the above range.

In the production method of the present invention, a step of joining the pigment solution and the surfactant solution (hereinafter, sometimes referred to as a previous-stage joining step), and a step of joining the joined liquid and the aqueous medium (hereinafter, the latter-stage). Sometimes referred to as a confluence process). At this time, it is good also as an embodiment which combines 3 or more times combining another merging process. The interval between the preceding merging and the latter merging may be adjusted as appropriate, but in order to maintain laminar flow and to suppress decomposition depending on the type of surfactant used, the interval between the two is successively reduced within 5 seconds. It is preferable to merge, and it is more preferable that it be within 1 second.
In the production method of the present invention, it is preferable to use a microreactor for at least the latter-stage merging, and it is preferable to use a microreactor for both the front and rear stages. A microreactor is a reactor having a thin channel that can form a microreaction field. In particular, the equivalent diameter of the flow path immediately after the merging site is preferably 2 mm or less, and more preferably 80 μm or more and 1 mm or less.

Equivalent diameter is also called equivalent diameter and is a term used in the field of mechanical engineering. When an equivalent circular pipe is assumed for a pipe having an arbitrary cross-sectional shape (a flow path in the present invention), the diameter of the equivalent circular pipe is referred to as an equivalent diameter. The equivalent diameter (d _eq ) is defined as d _eq = 4 A / p, using A: the cross-sectional area of the pipe, and p: the wet wetting length (circumferential length) of the pipe. When applied to a circular tube, this equivalent diameter corresponds to the circular tube diameter.

When water is poured into the tube, a thin tube is inserted into its central axis and colored liquid is injected, the colored liquid flows as a single line while the flow rate of water is low, and the water flows on the tube wall. It flows straight in parallel. However, when the flow velocity is increased and reaches a certain flow velocity, the water flow suddenly becomes turbulent, and the colored liquid is mixed with the water flow to become a colored flow. The former flow is called laminar flow, and the latter flow is called turbulent flow.
Whether the flow becomes a laminar flow or a turbulent flow depends on whether a Reynolds number, which is a dimensionless number indicating the state of the flow, is below a certain critical value. The smaller the Reynolds number, the easier it is to form a laminar flow. The Reynolds number Re of the flow in the pipe is expressed by the following equation.
Re = D <υ _x > ρ / μ
D is the equivalent diameter of the tube, <υ _x > is the average cross-sectional velocity, ρ is the density of the fluid, and μ is the viscosity of the fluid. As can be seen from this equation, the smaller the equivalent diameter, the smaller the Reynolds number. Therefore, in the case of an equivalent diameter of μm, it becomes easy to form a stable laminar flow. It can also be seen that the liquid physical properties of density and viscosity also affect the Reynolds number, and the smaller the density and the larger the viscosity, the smaller the Reynolds number and the easier it is to form a laminar flow.
A Reynolds number indicating a critical value is referred to as a critical Reynolds number. The critical Reynolds number is not always constant, but the next value is the standard.
Re <2300 laminar flow
Re> 3000 Turbulence
3000>Re> 2300 Transient state

  In the production method of the present invention, the flow after the merging of the organic pigment solution and the surfactant (first-stage merging) is performed under laminar flow, and the flow after the merging of the two merging liquids and the aqueous medium (second-stage merging). Is preferably carried out under laminar flow. The Reynolds number in each distribution process is not particularly limited, but the Reynolds number of the distribution from the previous stage merge to the subsequent stage merge is preferably 100 to 3000, and more preferably 300 to 2300. It is preferable that the Reynolds number of the distribution | circulation after a back | latter stage merge shall be 100-3000, and it is more preferable to set it as 300-2300.

  The type and shape of the reactor used in the production method of the present invention are not particularly limited, and any apparatus capable of at least continuous mixing can be used. One apparatus capable of continuous mixing may be used, or two or more apparatuses may be connected and used. Hereinafter, an embodiment of a preferable production apparatus (microreactor) that can be used in the production method of the present invention will be described.

FIG. 1-1 is a plan view schematically showing a manufacturing apparatus (a microreactor having a flow channel capable of continuous mixing) as an embodiment that can be used in the manufacturing method of the present invention, and FIG. It is sectional drawing of an II line cross section.
In the microreactor 10 of the present embodiment, the shape of the cross section perpendicular to the length direction of the flow path varies depending on the microfabrication technique used, but is a shape close to a trapezoid or a rectangle. The liquid injected from the introduction port 11 and the introduction port 12 by a pump or the like flows through the introduction channel 15. More specifically, the i liquid introduced from the introduction port 11 passes through the introduction flow path 15a, the ii liquid introduced from the introduction port 12 passes through the introduction flow path 15b, and both liquids enter the fluid confluence 15c. And then flow through the flow path 15d to the discharge port (collection port) 14. At this time, by adjusting the width and depth of the flow path so that the equivalent diameter of the flow path is micrometer, and the Reynolds number calculated from the flow velocity, viscosity, and density of the fluid is set to an appropriate value, the contact i The -ii combined liquid is preferably circulated as a stable laminar flow in the flow path 15d.

  In the microreactor 10 of the present embodiment, the iii liquid injected from the introduction port 13 by a pump or the like further flows through the introduction flow path 15e and comes into contact with the i-ii merged liquid flowing through the flow path 15d at the fluid merge point 15f. , I-ii-iii becomes a combined liquid and flows through the flow path 15g. By adjusting the Reynolds number of the fluid to an appropriate value, the three liquids in contact can be circulated as a stable laminar flow in the flow path 15g. That is, it can be set as the three-layer laminar flow of i-ii-iii liquid.

In the combined liquid flowing as a laminar flow through the flow paths 15d and 15g, the solutes included in the laminar flow are mixed or reacted by molecular diffusion at the interface between the laminar flows. Considering this, by changing the length of the flow path length A, that is, the distance from the confluence 15c to 15f, the solute at the fluid confluence 15f included in the i liquid and the ii liquid injected from the inlets 11 and 12 The desired degree of mixing can be achieved.
If the liquid introduced from the three inlets 11, 12, and 13 contains a solute that is extremely slowly diffusing, diffusion mixing between the laminar flows in the channels 15 d and 15 g does not occur so much, and the outlet 14 It may be mixed for the first time after reaching. When the three liquids to be injected are easily mixed in the flask, if the flow path length B is long, the liquid flow can be uniform at the discharge port, but when the flow path length B is short, Laminar flow is maintained up to the outlet.

  In the microreactor 10 of the present embodiment, the channel width, the channel depth, and the channel length are not particularly limited and can be appropriately selected. However, the channel width W and the channel depth H are 80 μm or more and 2 mm or less. Preferably, it is 100 μm or more and 1 mm or less, and more preferably 120 μm or more and 600 μm or less.

  In the production method of the present invention, unlike the apparatus of the above embodiment, a plurality of apparatuses that perform one merging may be connected and continuously mixed. The apparatus 20 in FIG. 2 is an embodiment in which two merging reactors 21 and 22 are connected to each other, and the i liquid, the ii liquid, and the iii liquid are mixed in the flow path 25 to obtain the iv liquid. It shows conceptually. In addition, although the specific structural example of the reactor which can be used is given below, this invention is limited to them and is not interpreted.

  FIG. 3A is an explanatory diagram of the reactor 30 having a Y-shaped channel, and FIG. 3B is a sectional view taken along the line III-III. The shape of the cross section orthogonal to the length direction of the flow path varies depending on the microfabrication technique used, but is preferably a trapezoidal or rectangular shape. At this time, it is preferable that the equivalent diameter of the flow path is a micrometer size. The solution injected by the pump or the like from the introduction port 31 and the introduction port 32 flows through the introduction channel 35. Specifically, the liquid i and the liquid ii contact and merge at the fluid merge point 35c via the introduction channel 15a and the introduction channel 35b, respectively, and preferably form a stable laminar flow and flow through the reaction channel 35d. . While flowing as a laminar flow, the solutes contained in the liquids are mixed by molecular diffusion at the interface between the laminar flows, and the reaction can proceed. In the case of a solute with extremely slow diffusion, there is a case where diffusion mixing between laminar flows does not occur and mixing is performed only after reaching the discharge port 34. When the two liquids to be injected are easily mixed in the flask, if the flow path length F is long, the liquid flow can be uniform at the outlet, but when the flow path length F is short, Laminar flow is maintained up to the outlet. When the two solutions to be injected do not mix in the flask and are separated into layers, the two liquids can flow as laminar flows and reach the outlet 34.

  FIG. 4A is an explanatory diagram of the reactor 40 having a cylindrical tube-type flow path provided with a flow path inserted on one side, and FIG. 4B is a cross-sectional view taken along the line IVa-IVa of the same apparatus. -3 is a sectional view taken along line IVb-IVb of the apparatus. The shape of the cross section perpendicular to the length direction of the flow path is preferably a circle or a shape close thereto. At this time, the diameter of the flow path of the cylindrical tube is preferably a micrometer size. The liquid injected from the introduction port 41 and the introduction port 42 by a pump or the like is brought into contact at the fluid junction point 43d through the introduction channel 43a and the introduction channel 43b, and preferably forms a stable cylindrical laminar flow. It flows through 43c. While flowing as a cylindrical laminar flow, the solutes contained in each laminar flow are mixed by molecular diffusion at the interface between the laminar flows, and the reaction can proceed. This device with a cylindrical tube-type flow path can take a large contact interface between two liquids, and since there is no part where the contact interface contacts the wall surface of the device, contact with the wall surface, such as when a solid (crystal) is generated by reaction The feature is that there is no crystal growth from the part and the possibility of blocking the flow path is low.

In the apparatus 50 shown in FIGS. 5A and 5B, the flow of the two liquids introduced from the introduction ports 51 and 52 is made to flow through the flow paths 53a and 53b, the confluence 53d, the flow path 53c, and the diversion point 53e. Further, it is possible to reach the outlets 54 and 55 through the flow paths 53f and 53g, for example, in a laminar flow. In other words, the liquid once joined is improved so that it can be divided again in the apparatus. Similarly, in FIG. 6, the two liquids introduced from the inlets 61 and 62 are circulated through the flow paths 63a and 63b and from the merging point 63d to the flow path 63c, and are divided through the divergence point 63e and the flow paths 63f and 63g. A device 60 of the aspect. Thereby, the divided two liquids are taken out from the discharge ports 64 and 65 and collected.
When these devices are used, reaction and separation can be performed simultaneously. Moreover, it can be avoided that the two liquids are finally mixed and the reaction proceeds too much or the crystal becomes coarse. When a product or a crystal is selectively present in one liquid, the product or the crystal can be obtained at a higher concentration than when the two liquids are mixed. In addition, by connecting several of these devices, there is an advantage that the extraction operation is performed efficiently.

  The microreactor apparatus 70 shown in FIG. 7 supplies one liquid A (in the figure, the liquid is indicated by an arrow indicating the direction of the flow. The same applies to the liquids B and C). Two divided supply channels 71A and 71B branched from the middle of the supply channel 71 so that the liquid A can be divided into two, and one undivided supply channel 72 for supplying the liquid B The micro flow path 73 that performs the reaction between the solution A and the solution B is formed so as to communicate with each other in one joining region 74. The divided supply channels 71A and 71B, the supply channel 72, and the microchannel 73 are arranged at equal intervals of 90 ° around the merge region 74 in substantially the same plane. That is, the central axes (one-dot chain lines) of the flow paths 71A, 71B, 72, and 73 intersect in a cross shape (intersection angle α = 90 °) in the merge region 74. In FIG. 7, only the supply path 71 for the liquid A is divided so that the supply amount can be increased as compared with the liquid B, but the supply path 72 for the liquid B may also be divided into a plurality. Further, the crossing angle α of the flow paths 71A, 71B, 72, 73 arranged around the merging region 74 is not limited to 90 ° and can be set as appropriate. Further, the number of divisions of the supply flow paths 71 and 72 is not particularly limited, but when the number is too large and the structure of the microreactor device 50 is complicated, the number of divisions is preferably 2 to 10. 2 to 5 is more preferable.

  FIG. 8 shows another embodiment of the planar microreactor apparatus of FIG. 7, and the crossing angle β formed by the central axes of the divided supply flow paths 81A and 81B with respect to the central axis of the supply flow path 82 is 90 in FIG. It is formed at 45 ° smaller than °. Further, the crossing angle α formed by the central axis of the micro flow path 73 with respect to the central axis of the divided supply flow paths 71A and 71B is set to 135 °.

  FIG. 9 shows still another aspect of the planar microreactor apparatus of FIG. 8, and the central axis of the divided supply channels 91A and 91B in which the liquid A flows with respect to the central axis of the supply channel 92 in which the liquid B flows. The formed crossing angle β is set to 135 ° larger than 90 ° in FIG. Further, the crossing angle α formed by the central axis of the micro flow path 93 with respect to the central axis of the divided supply flow paths 91A and 91B is 45 °. The crossing angles α and β of the supply flow channel 92, the divided supply flow channels 91A and 91B, and the micro flow channel 93 can be set as appropriate, but the cross-sectional area in the thickness direction of all of the merged liquid B and liquid A The crossing angles α and β are preferably set so as to satisfy S1> S2, where S1 is S1 and the radial cross-sectional area of the microchannel 93 is S2. This is because the contact area between the liquids A and B can be further increased and the diffusion mixing distance can be further reduced, so that instantaneous mixing is more likely to occur.

  FIG. 10 shows an embodiment of a three-dimensional microreactor apparatus, and is an exploded perspective view schematically showing three parts constituting the microreactor apparatus 100 in an exploded manner. The three-dimensional microreactor apparatus 100 of this embodiment is mainly composed of a supply block 101, a confluence block 102, and a reaction block 103 each having a cylindrical shape. In order to assemble the microreactor device 100, the cylindrical blocks 101, 102, and 103 are made to be cylindrical by aligning the side surfaces with each other in this order. For example, each block is bolted in this state.・ Tighten together with nuts.

  Two annular grooves 105, 106 are formed concentrically on the side surface 104 of the supply block 101 that faces the merging block 102. When the microreactor device 100 is assembled, the two annular grooves 106, Reference numeral 105 forms a ring-shaped channel through which the liquid B and the liquid A flow. Then, through holes 108 and 107 reaching the outer annular groove 106 and the inner annular groove 105 from the opposite side surface 114 of the supply block 101 not facing the merge block 102 are formed. Of the two through holes 108 and 107, a supply means (a pump, a connecting tube, etc.) for supplying the liquid A is connected to the through hole 108 communicating with the outer annular groove 106, and communicates with the inner annular groove 105. Supply means (a pump, a connection tube, etc.) for supplying the liquid B is connected to the through-hole 107. In FIG. 10, the liquid A is allowed to flow through the outer annular groove 106 and the liquid B is allowed to flow into the inner annular groove 105.

  A circular junction 110 is formed at the center of the side surface 109 of the junction block 102 facing the reaction block 103, and four long radial grooves 111 and four short radial grooves 112 are formed radially from the junction 110. Alternately drilled. These merging holes 110 and radial grooves 111 and 112 form a circular space that becomes the merging region 110 and a radial flow path through which the liquids A and B flow when the microreactor apparatus 100 is assembled. Further, among the eight radial grooves 111 and 112, through holes 115 are formed in the thickness direction of the merge block 102 from the tip of the long radial groove 111, and these through holes 115 are formed in the supply block 101. It communicates with the outer annular groove 106 described above. Similarly, through holes 116 are formed in the thickness direction of the merge block 102 from the tip of the short radial groove 112, and these through holes 116 communicate with the inner annular groove 105 formed in the supply block 101.

  Further, at the center of the reaction block 103, one through hole 113 communicating with the merging portion 110 in the thickness direction of the reaction block 103 is formed, and this through hole 113 becomes a micro flow path. As a result, the liquid A flows from the through hole 108 of the supply block 101 through the outer annular groove 106, through the through hole 115 of the merge block 102, and through the supply channel of the long radiation groove 111. The four divided flows reach the junction 110. On the other hand, the liquid B flows from the through hole 107 of the supply block 101 through the inner annular groove 105, through the through hole 116 of the confluence block 102, and through the supply channel of the short radiation groove 112. The four divided flows reach the junction 110. After the split flow of the liquid A and the split flow of the liquid B merge with their kinetic energy in the merge section 110, the flow direction changes by 90 ° and flows into the microchannel 113.

  In the production method of the present invention, using the apparatus of the above-described embodiment, the liquid i and the liquid ii are first combined and mixed with the pigment solution and the surface active solution, and then the aqueous medium is introduced as the liquid iii and combined and mixed. preferable. The flow rate of the pigment solution, the surfactant solution, and the aqueous medium is not particularly limited, but the flow rate ratio of the pigment solution and the aqueous medium is preferably 1: 1 to 1:20, and is preferably 1: 2 to 1:10. More preferably. The flow rate ratio between the pigment solution and the surfactant solution is preferably 1: 1 to 20: 1, and more preferably 2: 1 to 10: 1.

  In the production method of the present invention, when the pigment solution, the surfactant solution, and the aqueous medium are merged, their flow state is not particularly limited. At this time, a liquid obtained by joining the organic pigment solution and the surfactant solution flowing in a laminar flow state and the aqueous medium are combined, and the surfactant solution is mixed with the organic pigment solution and the aqueous medium. It is preferable to carry out so as to be interposed between them. When this distribution form is shown as a cross section (rectangular cross section) along line XI-XI of the apparatus shown in FIG. 1, it can be conceptualized as shown in FIG. At this time, the pigment solution is introduced as the i liquid into the introduction port 11, the ii liquid is introduced into the introduction port 12 and merged at the junction 15 c, and the flow path 15 d is circulated as a laminar flow. Thereafter, an aqueous medium to be the iii liquid is introduced from the introduction port 13, and the three liquids are co-flowed in the order of the i liquid, the ii liquid, and the iii liquid from the left as shown in FIG. As another embodiment, for example, when the iii liquid is introduced from the side as a laminar flow in which the i liquid and the ii liquid are laminated in the upper and lower sections, a cross section of three liquids as shown in FIG. Distribution state is obtained.

  In the production method of the present invention, it is preferable to form a laminar flow by feeding the surfactant solution so that it is circulated between the organic pigment solution and the aqueous medium. As a result, the surfactant can be effectively arranged at the place where the crystals are deposited, so that the efficiency of particle formation control can be increased and the amount of the surfactant can be reduced. In addition, particles having a smaller size can be obtained, and effects such as improvement of monodispersibility can be obtained. A surfactant with a low molecular weight has high mobility in the liquid and can be adsorbed quickly on the surface of the deposited pigment, so this effect is remarkable compared to the case where a polymer dispersant or the like is used as a dispersant. And fine and uniform particles can be formed. Many of the dispersants decompose in a strong alkali, and the dispersant that can be selected is limited in the method of coexisting the dispersant in the pigment solution dissolved in the alkali, but according to the method of the present invention, it can be widely selected. it can. The shape of the layer to be formed is not particularly limited, and may be a flat laminar flow or a cylindrical laminar flow.

  The production method of the present invention may include a step of heating the obtained dispersion. In particular, when fine particles are formed using a polymer dispersant, effects such as reduction in viscosity and improvement in dispersion stability can be expected by heating. The heating step can be selected as appropriate, for example, in the flow path after obtaining the pigment fine particles, in the collected dispersion, after purification or after concentration, but the operation is simple and the heating conditions are constant. Therefore, it is preferable to use the method in the flow path.

  By drying the organic pigment fine particle dispersion, a paste or solid of the organic pigment fine particles can be obtained. The drying method may be a normal method and is not particularly limited. For example, the drying method may be freeze drying, distillation under reduced pressure (evaporator), a combination thereof, or the like. The content of the organic pigment when solidified or concentrated is not particularly limited, but is preferably 5% by mass to 90% by mass, and more preferably 20% by mass to 80% by mass.

The pigment dispersion obtained by the method for producing an organic pigment fine particle dispersion of the present invention can be purified, concentrated and classified by filtration or centrifugation. For the purpose of increasing the fastness of the pigment, an ultraviolet absorber or an antioxidant may be added. In addition, additives such as a fragrance, an antifungal agent, a surface tension adjusting agent, a water-soluble resin, a bactericidal agent, a pH adjusting agent, and urea may be used depending on applications and purposes. The timing and method of addition of these are not particularly limited. For example, the following four aspects may be used, and any of these may be performed in combination.
(1) Add the organic pigment to the dissolved solution.
(2) Add to aqueous medium.
(3) A solution in which an organic pigment is dissolved and an aqueous medium are mixed and then added.
(4) The dispersion after mixing is concentrated and purified and then added.

  The organic pigment fine particles of the present invention preferably have high stability, and can be represented by the rate of change of the particle size due to the storage treatment as an index indicating the stability, for example, expressed by the rate of change of the volume average particle size Mv described above. be able to. The organic pigment fine particles of the present invention preferably have a change rate of 6.0% or less, for example, 5.0% or less when subjected to a heat storage process (for example, a storage process at 60 to 80 ° C. for 50 to 300 hours). Is more preferable, and 4.0% or less is particularly preferable.

The dispersion liquid of the organic pigment fine particles of the present invention can be, for example, a suitable inkjet ink. In the method, for example, the dispersion of the organic pigment fine particles of the present invention is purified and concentrated by centrifugation and / or ultrafiltration. To this, water-soluble high-boiling organic solvents such as glycerins and glycols are added, the pH is adjusted to about 7 to 9, and additives for surface tension, viscosity, antiseptic, etc. are added to the ink jet. Ink preparation is possible. The preferred viscosity when prepared as an ink-jet ink varies depending on the pigment type and concentration, but generally, for example, when it is 5% by mass, it is preferably 20 mPa · s or less, and more preferably 10 mPa · s or less. Particularly preferred is 5 mPa · s or less.
In addition, the above-described separation, concentration, preparation of liquid physical properties, etc. can be performed as appropriate to widely use in color filters and the like.

  Using the organic pigment fine particle dispersion of the present invention, the organic pigment fine particles and the vehicle (liquid portion excluding the pigment component in the paint, resin component and A medium such as water or an organic solvent). It is preferably used as a thermosetting paint or a photocurable paint containing a resin that undergoes a crosslinking reaction by heat or light.

  The present invention has the effect of expanding the choice of dispersants by avoiding problems of alkali decomposability and solubility. This increases the number of types of dispersants used in inks and paints. For example, it is possible to select dispersants that take into account not only various performances such as dispersion stability but also cost and environmental friendliness. It is to make.

(Example 1)
Pigment Yellow 128 (Ciba Specialty Chemicals, CROMOPHTAL YELLOW 8GNP (trade name)) 8 g, 28% sodium methoxide methanol solution (Wako Pure Chemical Industries, Ltd.) 6.3 g was dissolved in dimethyl sulfoxide 120 mL at room temperature. This was designated as i liquid (pigment solution). The concentration of added base to the pigment solution is calculated to be 0.27 mol / L. A solution obtained by dissolving 3.2 g of sodium di (2-ethylhexyl) sulfosuccinate (manufactured by Tokyo Chemical Industry Co., Ltd., molecular weight 445) (surfactant) in 20 mL of dimethyl sulfoxide was designated as ii solution (surfactant solution). Distilled water was designated as liquid iii.

  The fine pigment particle dispersion was synthesized using a quartz microreactor having a flow path shown in FIG. The widths (W) of the channels 15a, 15b, 15e, 15d, and 15g were 150 μm, the channel depth (H) was 150 μm, the channel length A and the channel length B were both 5 cm. A Teflon (registered trademark) tube having a length of 1 m and an equivalent diameter of 1 mm is connected to the inlets 11, 12, and 13 using a connector, and i liquid (inlet 11) and ii liquid (inlet 12) are connected to the tip. , Syringes containing iii liquid (inlet 13) were connected and set in a pump. This positional relationship is such that the ii liquid flows between the i liquid and the iii liquid in the flow path 15g (see FIG. 11A). A Teflon (registered trademark) tube having a length of 1 m and an equivalent diameter of 1 mm was also connected to the discharge port 14 using a connector.

  The liquid i was sent out at a liquid feeding speed of 1.5 mL / min, the liquid ii at 0.25 mL / min, and the liquid iii at a liquid feeding speed of 8 mL / min. Since a dispersion of Pigment Yellow 128 was obtained from the tip of the tube outlet, it was collected. The pH of the dispersion at this time was 12.0. The Reynolds number from when the i liquid and the ii liquid merge to the iii liquid and the Reynolds number after the iii liquid merge are calculated to be about 120 and 1000, respectively, which is a laminar flow region.

  This liquid was purified while adding distilled water with an ultrafiltration device (Advantech Toyo Co., Ltd., UHP-62K (trade name), molecular weight cut off 50,000) to eliminate the filtrate and to keep the volume constant. Concentrated to 0% by weight. The viscosity of the 5.0 mass% pigment dispersion is 4.8 mPa.s. s, The volume average particle diameter Mv of the pigment particles of this liquid was 27.1 nm, and the ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.34. The particle size (Mv) and monodispersity (Mv / Mn) of the pigment particles were diluted with distilled water to a pigment concentration of 0.2% by mass using Nanotrac UPA-EX150 (trade name) manufactured by Nikkiso Co., Ltd. And measured at room temperature (around 25 ° C.). This also applies to the following examples and comparative examples.

(Example 2)
A 5.0 mass% pigment dispersion was prepared in the same manner as in Example 1 except that the amount of sodium di (2-ethylhexyl) sulfosuccinate used in Example 1 was changed to 8.0 g. The results of measuring the diameter are shown in Table 1.

(Example 3)
The sodium di (2-ethylhexyl) sulfosuccinate used in Example 1 was changed to 56 g of Aqualon KH-10 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., average molecular weight 780) of the same mass, otherwise A pigment 5.0 mass% dispersion was prepared in the same manner as in Example 1, and the viscosity and particle size measured were shown in Table 1.

Example 4
In Example 1, only the relative positional relationship for introducing the three liquids was changed. The ii liquid was introduced into the inlet 11, the i liquid was introduced into the inlet 12, and the iii liquid was introduced into the inlet 13. That is, in the apparatus shown in FIG. 1, the pigment solution was arranged in the center in the flow path 15g, and a 5.0% by mass pigment dispersion was prepared in the same manner as in Example 1 except that the viscosity and The results of measuring the particle diameter are shown in Table 1.

(Example 5)
In Example 3, only the relative positional relationship for introducing the three liquids was changed. The ii liquid was introduced into the inlet 11, the i liquid was introduced into the inlet 12, and the iii liquid was introduced into the inlet 13. That is, the pigment solution was arranged in the center in the flow path 15g of FIG. 1, and a 5.0% by mass pigment dispersion was prepared in the same manner as in Example 3 except that the viscosity and particle size were measured. It is shown in Table 1.

(Example 6)
Dispersion liquids were prepared using the reaction apparatus having the flow path configuration of the connected form shown in FIG. 2 using the i liquid, the ii liquid, and the iii liquid having the same liquid composition as that used in Example 1. At this time, as reactors 31 and 32, a fine particle dispersion of PY-128 using a Y-shaped three-way joint (model JYF-305 (trade name) manufactured by Tokyo Rika Kikai Co., Ltd.) having an equivalent diameter of 500 μm. Synthesis was performed. At this time, as shown in FIG. 2, i liquid and ii liquid were introduced from two ports of the first three-way joint, and this combined liquid and iii liquid were introduced into the second three-way joint and remained. The pigment dispersion (iv liquid) was collected from the mouth. For connection, a Teflon (registered trademark) tube having an equivalent diameter of 1 mm and a connector were used. The flow rates of liquid i, liquid ii, and liquid iii were 3.0 ml / min, 0.5 ml / min, and 16 ml / min, respectively. At this time, it was difficult to clearly grasp the relative positional relationship of the flow cross sections of the liquid i, liquid ii, and liquid iii after merging (even if laminar flow was maintained in the flow path, for example, FIG. (3) The three liquids may form a laminar flow as in (a), but as in FIG. 11 (b), and may change with time. The pigment dispersion obtained from the outlet was purified and concentrated in the same manner as in Example 1 to prepare a 5.0% by mass pigment dispersion, and the results of measuring the viscosity and particle size are shown in Table 1.

(Comparative Example 1)
PY-128 was prepared by mixing the liquid i and liquid ii used in Example 1 with a beaker in advance into a pigment solution (liquid ia) and mixing this liquid and the aqueous medium (liquid iii) with the following flow reactor. A fine particle dispersion was obtained. That is, 8 g of Pigment Yellow 128, 6.3 g of 28% sodium methoxide methanol solution, and 3.2 g of sodium di (2-ethylhexyl) sulfosuccinate dissolved in 140 mL of dimethyl sulfoxide were prepared, and this was used as IA solution. . The concentration of added base to the pigment solution is calculated to be 0.23 mol / L.

  Instead of the quartz reactor used in Example 1, a Y-shaped three-way joint (Tokyo Rika Kikai Co., Ltd., model JYF-305 (trade name)) having an inner diameter of 0.5 mm was used, and three inlets were used. A Teflon (registered trademark) tube having a length of 1 m and an equivalent diameter of 1 mm was connected to the two using a connector, and syringes containing ia liquid and distilled water (liquid iii) were connected to each other and set in a pump. A Teflon (registered trademark) tube having a length of 1.5 m and an equivalent diameter of 500 μm was connected to the other port as an outlet. The liquid ia was sent out at a liquid sending speed of 3.5 mL / min, and the liquid iii was sent out at a liquid feeding speed of 16 mL / min. The obtained dispersion was treated in the same manner as in Example 1 to prepare a 5.0% by mass pigment dispersion, and the results of measuring the viscosity and particle size are shown in Table 1. At this time, the pH of the dispersion was 12.5. In the preparation of the liquid ia, 4 hours had elapsed from the start of the mixing of the liquid i and the liquid ii to the start of the liquid feeding, and the flow was continued for 20 minutes.

(Comparative Example 2)
JP-A-2006-104448, paragraph [0077], 2- (4-methylphenyl) ethyl vinyl ether, 2- (2-methoxyethyloxy) ethyl vinyl ether, ethyl 4- (2-vinyloxy) ethoxybenzoate A triblock copolymer P1 (polymer dispersing agent, mass average molecular weight 26,000) having a segment of was synthesized. A 5.0 mass% pigment dispersion was prepared in the same manner as in Example 1 except that sodium di (2-ethylhexyl) sulfosuccinate used in Example 1 was changed to 16 g of block polymer P-1, and the viscosity and particle size were determined. The results of measuring are shown in Table 1.

(Comparative Example 3)
A 5.0 mass% pigment dispersion was prepared in the same manner as in Example 1 except that sodium di (2-ethylhexyl) sulfosuccinate used in Example 1 was changed to 3.2 g of the block polymer P-1. The results of measuring the particle diameter are shown in Table 1.

（注１）顔料１００質量部対する界面活性剤もしくは高分子分散剤の質量部

(Note 1) parts by mass of surfactant or polymer dispersant with respect to 100 parts by mass of pigment

  As can be seen from the results shown in Table 1, the pigment dispersion of the comparative example has a large particle size (Comparative Examples 1 and 3), and even if the particle size can be kept small, a large amount of the polymer dispersant is used. It turns out that it is necessary (Comparative Example 2). On the other hand, since the dispersion of the present invention obtained in the examples exhibits high dispersion stability even if the amount of the surfactant is small, both the low viscosity and the dispersibility of the dispersion can be achieved (Example 1). 2 and Comparative Examples 2 and 3), and the pigment particles contained therein have a small particle size and a uniform particle size. It can be seen that the dispersion of the dispersant solution (liquid ii) at this time allows the pigment fine particles to have a smaller particle size (Examples 1 and 4 and 6 are compared, Example 3). And 5).

(Example 7)
About the component composition of the i liquid used in Example 1, the pigment was 8 g of 2,9-dimethylquinacridone (manufactured by Clariant, HOSTAPERM PINK E (trade name)), and 28% sodium methoxide methanol solution (Wako Pure Chemical Industries, Ltd.) 18.1 g, dimethyl sulfoxide 120 mL. The concentration of added base to the pigment solution is calculated to be 0.78 mol / L. Others were prepared in the same manner as in Example 1 to prepare a 5.0 mass% pigment dispersion, and the results of measuring the viscosity and particle size are shown in Table 2. The pH of the obtained dispersion was 12.6.

(Example 8)
Using the i liquid, the ii liquid, and the iii liquid used in Example 7, the dispersion liquid was prepared in a relative positional relationship in which the three liquids shown in Example 5 were introduced. That is, in the apparatus of FIG. 1, the ii liquid was introduced from the inlet 11, the i liquid was introduced from the inlet 12, and the iii liquid was introduced from the inlet 13. Table 2 shows the results obtained by preparing a 5.0 mass% pigment dispersion in the same manner as in Example 7 and measuring the viscosity and particle size.

(Comparative Example 4)
Sodium di (2-ethylhexyl) sulfosuccinate placed in the liquid ii in Example 7 was changed to the same amount of the block copolymer P-1, and 5.0 mass% of the pigment was otherwise obtained in the same manner as in Example 7. Table 2 shows the results of preparing the dispersion and measuring the viscosity and particle size.

(Comparative Example 5)
A mixture of liquid i and liquid ii used in Example 7 in advance was used as a pigment solution, and this liquid and an aqueous medium were mixed in a three-way reactor to obtain a fine particle dispersion of 2,9-dimethylquinacridone. That is, 8 g of 2,9-dimethylquinacridone, 18.1 g of 28% sodium methoxide methanol solution, and 3.2 g of sodium di (2-ethylhexyl) sulfosuccinate dissolved in 140 mL of dimethyl sulfoxide at room temperature were prepared. A liquid was used. The concentration of added base to the pigment solution is calculated to be 0.67 mol / L.
This iB liquid and distilled water (iii liquid) were sent out at a liquid feed speed of iB liquid 3.5 mL / min and iii liquid 16 mL / min, respectively. The resulting dispersion was treated in the same manner to prepare a 5.0% by mass pigment dispersion, and the viscosity and particle size measured were shown in Table 2. The pH of the obtained dispersion was 12.5. In addition, 4 hours passed from the start of preparation of iB liquid to the start of liquid feeding, and the flow was continued for 20 minutes.

（注１）顔料１００質量部対する界面活性剤もしくは高分子分散剤の質量部

(Note 1) parts by mass of surfactant or polymer dispersant with respect to 100 parts by mass of pigment

  As can be seen from the results shown in Table 2 above, even with different pigment types (PR-122), according to the present invention, the low viscosity of the dispersion is maintained, and the particle diameter is extremely small and uniform. It can be seen that the present invention has an excellent effect of being obtained. At this time, it can be seen that a uniform solution having a smaller particle diameter can be obtained by allowing the dispersing agent solution (liquid ii) to intervene (refer to Examples 7 and 8).

Example 9 Preparation of Inkjet Ink An inkjet ink was prepared using the 5% concentration dispersion described in Example 7 that had been purified and concentrated by ultrafiltration and had the following composition.
Organic pigment (3.5%)
Olfine E1010 (2.0%)
Glycerin (10%)
Water (84.5%)
When a droplet ejection test was conducted as ink of PM-D600 (trade name) manufactured by Seiko Epson Corporation, good printing was obtained without clogging.

(Example 10) Preparation of paint A paint was prepared by mixing with a resin at the following ratio using each of the 5% concentration dispersion liquids described in Example 7 after purification and concentration by ultrafiltration.
Organic pigment (5%): Jurimer ET-410 (trade name, manufactured by Nippon Pure Chemical Co., Ltd., 30%) = 2: 1
When this was dropped on a glass plate with a dropper and dried by heating at 40 ° C. for 2 hours, a transparent and vivid coating film was obtained.

It is a top view which shows typically the manufacturing apparatus as one Embodiment which can be used for the manufacturing method of this invention. It is sectional drawing of the II line cross section of FIGS. 1-1. It is apparatus explanatory drawing which shows notionally the manufacturing apparatus as another embodiment which can be used for the manufacturing method of this invention. It is a top view which shows typically the reaction apparatus which has a Y-shaped flow path on one side. It is sectional drawing of the III-III line cross section of FIGS. It is a longitudinal cross-sectional view which shows typically the reaction apparatus which has a cylindrical tube type flow path provided with the flow path penetrated in the one side. FIG. 4 is a transverse sectional view taken along line IVa-IVa in FIG. 4-1. FIG. 4 is a transverse sectional view taken along line IVb-IVb in FIG. It is a top view which shows typically the reaction apparatus which has a Y-shaped channel on both sides. It is sectional drawing of the VV sectional view of FIG. It is sectional drawing which shows typically the reaction apparatus which has a cylindrical tube type flow path provided with the flow path penetrated on both sides. 1 is a plan sectional view schematically showing one embodiment of a planar microreactor. It is a plane sectional view showing typically another embodiment of a planar type microreactor. It is a plane sectional view showing typically another embodiment of a planar type microreactor. 1 is an exploded perspective view schematically showing one embodiment of a three-dimensional microreactor. FIG. It is sectional drawing which shows notionally the relative positional relationship when 3 liquid joins on laminar flow conditions.

Explanation of symbols

10, 20, 30, 40, 50, 60, 70, 80, 90, 100 Reactor 21, 22 Single confluence reactor 11, 12, 13, 31, 32, 41, 42, 51, 52, 61, 62 Introduction Outlets 14, 34, 35, 44, 54, 55, 64, 65 outlets 15, 15a, 15b, 15d, 15e, 15g, 25, 35, 35a, 35b, 35d, 43a, 43b, 43c, 53, 53a, 53b, 53c, 53f, 53g, 63a, 63b, 63c, 63f, 63g, 71, 71A, 71B, 72, 73, 81, 81A, 81B, 82, 83, 91, 91A, 91B, 92, 93 Flow path 15c , 15f, 35c, 43d, 53d, 63d, 74, 84, 94 Fluid junction 53e, 63e Fluid branch point 101 Supply block 102 Merge block 103 Reaction block Lock 106 Outer annular groove 105 Inner annular grooves 107, 108 Through hole 110 of supply block Merging portion (merging area)
111 Long radial groove 112 Short radial groove 115, 116 Through hole 113 in confluence block Through hole (micro flow path) in reaction block

Claims (11)

  An organic pigment solution obtained by dissolving an organic pigment in an organic solvent and a surfactant solution obtained by dissolving a surfactant having a molecular weight of less than 1,000 in an organic solvent are combined in a flow path to form a combined solution. And a method of producing a dispersion of fine organic pigment particles, comprising the step of further flowing and joining the aqueous medium and the aqueous medium to produce fine particles of the organic pigment.   2. The method for producing an organic pigment dispersion according to claim 1, wherein the organic pigment solution is a solution obtained by dissolving the organic pigment in the presence of an alkali.   The organic pigment according to claim 1 or 2, wherein the step of joining the combined solution of the organic pigment solution and the surfactant solution and the aqueous medium is performed in a flow path having an equivalent diameter of 2 mm or less. A method for producing a dispersion.   The step of joining the organic pigment solution and the surfactant solution and the step of joining the combined solution and the aqueous medium are both performed in a flow path having an equivalent diameter of 2 mm or less. The manufacturing method of the organic pigment dispersion of any one of these.   After the organic pigment solution and the surfactant solution are merged in the flow path, the organic pigment solution and the surfactant solution are in a laminar flow state until the merged liquid and the aqueous medium are merged. It distribute | circulates, The manufacturing method of the organic pigment dispersion of any one of Claims 1-4 characterized by the above-mentioned.   The surfactant solution intervenes between the organic pigment solution and the aqueous medium such that the combined solution of the organic pigment solution and the surfactant solution flowing in a laminar flow state and the aqueous medium are combined. 6. The method for producing an organic pigment dispersion according to claim 5, wherein the method is carried out as follows.   The mass of the surfactant in the dispersion is 0.5 times or less with respect to the mass of the organic pigment, The organic pigment dispersion according to any one of claims 1 to 6, Production method.   The method for producing an organic pigment dispersion according to any one of claims 1 to 7, wherein a compound decomposable with respect to alkali is used as the surfactant.   The method for producing an organic pigment dispersion according to any one of claims 1 to 8, wherein the organic pigment fine particles have a volume average particle size (Mv) of 10 nm or more and 50 nm or less.   Ink for inkjet recording containing the said organic pigment fine particles in the dispersion obtained by the manufacturing method of any one of Claims 1-9.   The coating material containing the said organic pigment fine particles in the dispersion obtained by the manufacturing method of any one of Claims 1-9.

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