JP2007270051A - Manufacturing method of dispersion of organic pigment fine particles and organic pigment fine particles obtained by the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of preparing, simply and with good purity, a dispersion of organic pigment fine particles in which a polymer is fixed on the fine particles by performing from the generation of the organic pigment fine particles to the polymerization of a polymerizable compound being caused to be present together with the particles in one vessel; to provide the organic pigment fine particles obtained thereby; and, further, to provide a method for inexpensively manufacturing organic pigment fine particles excellent in dispersion stability and storage stability that have small sizes and a narrow particle size distribution (high degree of monodispersity) and that are obtained by polymerizing the polymerizable compound contained in the mixed solution (preferably by immobilizing the polymer) and a method for inexpensively manufacturing the dispersion. <P>SOLUTION: The manufacturing method of the organic pigment fine particles comprises, in preparing a mixed solution by mixing a solution dissolving an organic pigment and an aqueous medium, generating fine particles of the organic pigment in the mixed solution and polymerizing a polymerizable compound contained in the mixed solution, carrying out the polymerization of the above polymerizable compound in the co-presence of one or more high molecular weight polymerization initiators and one or more of low molecular weight polymerization initiators. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an organic pigment fine particle dispersion, and organic pigment fine particles obtained thereby. More specifically, a solution in which an organic pigment is dissolved and an aqueous medium are mixed (preferably in a microreaction field) to form a pigment as fine particles, and a coexisting polymerizable compound is polymerized (preferably the polymer into pigment fine particles). The present invention relates to a method for producing an organic pigment fine particle dispersion and an organic pigment fine particle obtained thereby.

  Pigments exhibit vivid color tone and high coloring power, and are widely used in many fields. For example, paints, printing inks, electrophotographic toners, ink-jet inks, color filters, and the like can be cited as applications, and now they are important compounds indispensable in daily life. The general properties of pigments and the classification by use are described in Non-Patent Document 1, for example. Among the above-mentioned uses, high performance is required, and particularly important in practical use include pigments for inkjet inks and pigments for color filters.

  Dyes have been used as coloring materials for ink-jet inks, but there are drawbacks in terms of water resistance and light resistance, and pigments have been used to improve them. The image obtained with the pigment ink has a remarkable advantage in that it is excellent in light resistance and water resistance as compared with the image obtained by the dye-based ink. However, it is difficult to uniformly refine (ie, monodisperse) nanometer size that can penetrate into the voids on the paper surface, and the adhesiveness to paper is inferior, and this improvement is required.

  An important application of pigments is a color filter used for a CCD sensor. In recent years, with the increase in the number of pixels of a digital camera, it is desired to make the layer thinner. Although organic pigments are used for color filters, the thickness of the filter greatly depends on the particle size, so in this field, it is possible to manufacture monodisperse and stable fine particles at the nanometer size level. It has been demanded.

  Organic pigment fine particle production methods are broadly classified into a breakdown method for producing from a bulk material by pulverization, etc., and a build-up method for producing by particle growth from the gas phase or liquid phase (see Non-Patent Document 2, etc.). . In general, a breakdown method (pulverization method) is widely used. However, in this method, it is difficult to obtain an organic substance with a nanometer size, the productivity is extremely low, and applicable substances are limited.

  As a method for making up for this drawback, it has been proposed to encapsulate pigment fine particles with a resin and encapsulate them (see Non-Patent Documents 3 to 6, etc.). Although it has been attempted to improve the water resistance and light resistance by this method and increase the gloss of printing, it has not been able to meet the recent demand for higher image quality. This is because these methods are based on the breakdown method, and the fine particles cannot be adjusted to a desired minute size. Further, it is necessary to make it fine by pulverization and to completely adsorb the resin separately, which requires a great deal of time and energy in terms of productivity.

On the other hand, a pigment is also dispersed by a dispersant. At this time, simply adsorbing the dispersant on the pigment surface lacks long-term stability, water resistance and viscosity stability, and when used as an inkjet ink, the dispersion is caused by a strong shearing force when ejected from the nozzle. The agent may be detached, deteriorated, or the nozzle may be blocked.
In contrast, many methods have been studied. For example, chemical modification of the pigment surface by oxidation treatment or the like, formation of a chemical bond between the pigment surface and a soluble group by grafting or the like (see Patent Document 1). However, it is difficult to carry out the reaction completely in any case, and as a result, the properties of the dispersion are not improved. In addition, in order to ensure stability, it may be possible to increase the content of the dispersant, but this causes another problem such as a decrease in printing performance or an excessive increase in viscosity. Become.

  Further, a method of emulsion polymerization by adding a polymerizable surfactant to a pigment obtained by the breakdown method is known (see Patent Document 2). However, in the emulsion polymerization disclosed here, a large amount of monomer is required in order to completely adsorb the monomer on the surface of the pigment fine particles. Also, since the breakdown method is used, the size of the pigment is large and it is necessary to make it uniform in a finer range. Furthermore, this method requires a pulverization process, consumes a large amount of energy, and requires a switching of process equipment to cause a polymerization reaction, resulting in low productivity.

  On the other hand, in recent years, a method of producing nanometer-sized organic fine particles by a build-up method has been studied. For example, the manufacturing method by a microchemical process is mentioned (refer patent document 3, 4). However, it is still not sufficient to meet the recent high demands such as ink-jet ink, and further improvement and development is desired.

Japanese Patent Laid-Open No. 10-316909 JP 2005-97517 A European Patent No. 1516896A1 JP 2005-307154 A “Pigment Dispersion Stabilization and Surface Treatment Technology / Evaluation” 2001, pages 123-224, Technical Information Association. "Chemical Course of 4th Edition", Volume 12 of the Chemical Society of Japan, Year, 411-488, Maruzen Co., Ltd. “Preparation of nanoparticle and dispersion / aggregation control and evaluation”, Chapter 1, Section 4 Various synthesis methods and problems of polymer nanoparticle, Technical Information Association, 2003. “Improvement of image quality with water-based pigment inks” Kengo Yasui, Kozue Sunouchi (Dainippon Ink & Chemicals) DIC Tech Rev, No. 10; 11-18, 2004. “Microencapsulated pigment jet ink” Hiroshi Harada, Sadahiro Inoue (Dainippon Ink and Chemicals) DIC Tech Rev, No. 9; 1-7, 2003. “Micro / Nanocapsule Technology Pigment Microcapsulation and Application to Inkjet” Masao Tanaka (Dainippon Ink & Chemicals) Industrial Materials, Vol. 52, No. 6, pp. 42-45, 2004.

  The present invention is a method for producing organic pigment fine particles in a single tank from the production of organic pigment fine particles to the polymerization of the polymerizable compound coexisted therewith, and a method for producing organic pigment fine particles with high purity, The purpose is to provide fine pigment particles. Further, the present invention provides organic pigment fine particles having a small size and a narrow particle size distribution (high monodispersity), and polymerizing a polymerizable compound contained in the mixed solution (preferably fixing the polymer). An object of the present invention is to provide organic pigment fine particles having excellent dispersion stability and storage stability and an inexpensive method for producing the dispersion.

［一般式（１）中、Ｒ^１〜Ｒ^４はそれぞれ独立に水素原子または置換基を表す。このときＲ^１〜Ｒ^４は互いに結合して環を形成していてもよい。ｍは０または正の整数を表す。一般式（２）中、Ｒ^５〜Ｒ^７はそれぞれ独立に水素原子または置換基を表す。このときＲ^５〜Ｒ^７は互いに結合して環を形成していてもよい。ｎは０または正の整数を表す。］
（７） 前記一般式（１）中、ｍが０または１であることを特徴とする（６）のいずれか１項に記載の有機顔料微粒子分散液の製造方法。
（８） 重合性化合物がＮ−ビニルピロリドンであることを特徴とする（１）〜（７）のいずれか１項に記載の有機顔料微粒子分散液の製造方法。
（９） 前記一般式（２）中、ｎが０または１であることを特徴とする（６）のいずれか１項に記載の有機顔料微粒子分散液の製造方法。
（１０） 重合性化合物として重合性界面活性剤の１種類以上を前記混合液中に含有させることを特徴とする（１）〜（９）のいずれか１項に記載の有機顔料微粒子分散液の製造方法。
（１１） 前記一般式（１）または（２）で表される化合物の１種以上と、重合性界面活性剤の１種以上とを前記混合液中に含有させることを特徴とする（６）〜（１０）に記載の有機顔料微粒子分散液の製造方法。
（１２） 重合性界面活性剤が、下記一般式（３）または（４）で表される化合物であることを特徴とする（１０）または（１１）に記載の有機顔料微粒子分散液の製造方法。

［一般式（３）中、Ｒ^８はアルキル基またはアリール基を表す。一般式（４）中、Ｒ^９〜Ｒ^１１はそれぞれ独立に水素原子、アルキル基、及びアリール基のいずれかを表し、Ｒ^１２〜Ｒ^１６はそれぞれ独立に水素原子もしくは置換基を表す。］
（１３） 有機顔料溶液がアルカリ性であることを特徴とする（１）〜（１２）のいずれか１項に記載の有機顔料微粒子分散液の製造方法。
（１４） 有機顔料溶液と水性媒体とを混合する過程で水素イオン指数（ｐＨ）を変化させることを特徴とする（１）〜（１３）に記載の有機顔料微粒子分散液の製造方法。
（１５） 有機顔料を溶解した溶液と水性媒体とを流路（チャンネル）中に層流として流通させ、その層流過程で互いに接触させて混合することを特徴とする（１）〜（１４）に記載の有機顔料微粒子分散液の製造方法。
（１６） 流路がマイクロ反応場であることを特徴とする（１５）に記載の有機顔微粒子料分散液の製造方法。
（１７） 流路の等価直径が１０ｍｍ以下であることを特徴とする（１６）に記載の有機顔料微粒子分散液の製造方法。
（１８） （１）〜（１７）に記載の製造法により得られた有機顔料微粒子であって、モード径が１μｍ以下であることを特徴とする有機顔料微粒子。 The above problems have been achieved by the following means.
(1) When mixing a solution in which an organic pigment is dissolved and an aqueous medium to form a mixed solution, forming fine particles of the organic pigment in the mixed solution, and polymerizing the polymerizable compound contained in the mixed solution A method for producing an organic pigment fine particle dispersion, wherein the polymerizable compound is polymerized in the presence of at least one kind of a high molecular weight polymerization initiator and at least one kind of a low molecular weight polymerization initiator.
(2) A solution in which an organic pigment is dissolved and an aqueous medium are circulated through a channel having an equivalent diameter of 1 mm or less to form a liquid flow, and both are brought into contact with each other to be mixed (1 ). The method for producing an organic pigment fine particle dispersion according to (1).
(3) The organic pigment fine particle dispersion liquid according to (1) or (2), wherein at least one of the high molecular polymerization initiator and the low molecular polymerization initiator has an azo group (—N═N—). Production method.
(4) Any one of (1) to (3), wherein at least one of the organic pigment solution and the aqueous medium contains at least one polymer polymerization initiator before mixing the two solutions. The manufacturing method of the organic pigment fine particle dispersion liquid of description.
(5) The organic pigment fine particle dispersion described in any one of (1) to (4), wherein the polymer of the polymerizable compound is immobilized on the pigment fine particles by polymerizing the polymerizable compound. Liquid manufacturing method.
(6) The organic pigment fine particles as described in any one of (1) to (5), wherein one or more polymerizable compounds represented by the following general formula (1) or (2) are contained. A method for producing a dispersion.

[In General Formula (1), R ^{1 to} R ⁴ each independently represents a hydrogen atom or a substituent. At this time, R ^{1 to} R ⁴ may be bonded to each other to form a ring. m represents 0 or a positive integer. In General Formula (2), R ^{5 to} R ⁷ each independently represent a hydrogen atom or a substituent. At this time, R ^{5 to} R ⁷ may be bonded to each other to form a ring. n represents 0 or a positive integer. ]
(7) The method for producing an organic pigment fine particle dispersion according to any one of (6), wherein m is 0 or 1 in the general formula (1).
(8) The method for producing an organic pigment fine particle dispersion according to any one of (1) to (7), wherein the polymerizable compound is N-vinylpyrrolidone.
(9) The method for producing an organic pigment fine particle dispersion according to any one of (6), wherein n is 0 or 1 in the general formula (2).
(10) The organic pigment fine particle dispersion according to any one of (1) to (9), wherein one or more polymerizable surfactants are contained in the mixed liquid as a polymerizable compound. Production method.
(11) One or more of the compounds represented by the general formula (1) or (2) and one or more of a polymerizable surfactant are contained in the mixed solution (6) -The manufacturing method of the organic pigment fine particle dispersion liquid as described in (10).
(12) The method for producing an organic pigment fine particle dispersion according to (10) or (11), wherein the polymerizable surfactant is a compound represented by the following general formula (3) or (4): .

[In General Formula (3), R ⁸ represents an alkyl group or an aryl group. In General Formula (4), R ^{9 to} R ¹¹ each independently represent any of a hydrogen atom, an alkyl group, and an aryl group, and R ^{12 to} R ¹⁶ each independently represent a hydrogen atom or a substituent. ]
(13) The method for producing an organic pigment fine particle dispersion according to any one of (1) to (12), wherein the organic pigment solution is alkaline.
(14) The method for producing an organic pigment fine particle dispersion according to any one of (1) to (13), wherein the hydrogen ion exponent (pH) is changed in the course of mixing the organic pigment solution and the aqueous medium.
(15) A solution in which an organic pigment is dissolved and an aqueous medium are circulated as a laminar flow in a channel, and are brought into contact with each other and mixed in the laminar flow process (1) to (14) The manufacturing method of the organic pigment fine particle dispersion liquid of description.
(16) The method for producing an organic facial fine particle material dispersion according to (15), wherein the flow path is a micro reaction field.
(17) The method for producing an organic pigment fine particle dispersion liquid according to (16), wherein the flow path has an equivalent diameter of 10 mm or less.
(18) Organic pigment fine particles obtained by the production method according to any one of (1) to (17), wherein the mode diameter is 1 μm or less.

According to the production method of the present invention, organic pigment fine particles having a small size and a narrow particle size distribution (highly monodispersed) can be obtained, and the polymerizable compound coexisting with the generated pigment fine particles is polymerized (preferably By immobilizing the polymer, the organic pigment fine particles having a high dispersion stability and storage stability and a dispersion thereof can be obtained.
Further, according to the production method of the present invention, it can be continuously performed as a process from the production of organic pigment fine particles to the polymerization of the polymerizable compound coexisted there, without the need for separation of fine particles and switching of the process, A simple and pure organic pigment can be obtained, and organic pigment fine particles having a uniform particle size (monodispersed organic pigment fine particles) can be obtained by control. In addition, by using a high molecular polymerization initiator and a low molecular polymerization initiator in combination, the above-described excellent organic pigment fine particles can be produced at a low cost in a wide range of pigment types.

The present invention is described in detail below.
In the method for producing an organic pigment fine particle dispersion of the present invention, a solution in which an organic pigment is dissolved and an aqueous medium are mixed, and in the process, the pigment is precipitated as fine particles. Examples of the mixing method include a method of pouring an aqueous medium into the organic pigment solution, a method of pouring the organic pigment solution into the aqueous medium, and mixing the organic pigment solution and the aqueous medium at the same time. In that case, it is preferable to promote mixing by stirring.
Moreover, it can also be made to mix using a flow path, and in this case, for example, an organic pigment solution and an aqueous medium can be circulated in the flow path as a liquid flow, and both liquids can be contact-mixed. In other words, the desired pigment dispersion can be obtained by a continuous flow method (Note that the method of contacting and mixing a plurality of liquid streams in this flow path is a jet method (spraying from a nozzle) in which contact time and reaction time cannot be precisely controlled. This is different from the method disclosed in JP 2002-155221 A, US Pat. No. 6,537,364, etc.). At this time, it is preferable to make both into a laminar flow in the flow path, contact each other in the laminar flow process, and contact at the laminar flow interface. Any apparatus may be used as long as it has a channel capable of forming a laminar flow, and the channel is preferably a channel having an equivalent diameter capable of forming a micro reaction field.

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. The equivalent diameter is used to estimate the flow or heat transfer characteristics of the pipe based on the data of the equivalent circular pipe, and represents the spatial scale (typical length) of the phenomenon. The equivalent diameter is d _eq = 4a ² / 4a = a for a regular square tube with one side a, and for a regular triangle tube with one side a,

流路高さｈの平行平板間の流れではｄ_ｅｑ＝２ｈとなる（例えば、（社）日本機械学会編「機械工学事典」１９９７年、丸善（株）参照）。

In the flow between parallel flat plates having a flow path height h, d _eq = 2h (for example, see “Mechanical Engineering Dictionary” edited by The Japan Society of Mechanical Engineers, 1997, Maruzen Co., Ltd.).

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 <v _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

As the equivalent diameter of the flow path decreases, the surface area per unit volume (specific surface area) increases, but when the flow path becomes microscale, the specific surface area increases dramatically, and the heat transfer efficiency through the wall of the flow path is Become very expensive. Since the heat transfer time (t) in the fluid flowing through the flow path is expressed by t = d _eq ² / α (α: the thermal diffusivity of the liquid), the heat transfer time becomes shorter as the equivalent diameter becomes smaller. That is, when the equivalent diameter is 1/10, the heat transfer time is 1/100. When the equivalent diameter is microscale, the heat transfer speed is extremely fast.

  That is, since the Reynolds number is small in a micro-size space having an equivalent diameter of microscale, the flow reaction can be performed under stable laminar flow control. Since the interfacial surface area between the laminar flows is very large, it is possible to mix the component molecules at high speed and accurately by molecular diffusion between the interfaces while maintaining the laminar flow. In addition, the use of a channel wall having a large surface area enables precise temperature control and precise control of reaction time by flow rate control of the flow reaction. Therefore, in the present invention, among the channels forming the laminar flow, a microscale channel having an equivalent diameter that is a field capable of highly reaction control as described above is defined as a micro reaction field.

  As shown in the description of the Reynolds number, the formation of a laminar flow is greatly influenced not only by the size of the equivalent diameter but also by the flow conditions including liquid properties such as viscosity and density. Therefore, in the present invention, the equivalent diameter of the flow path is not limited, but a size that can easily form a laminar flow is preferable. Preferably it is 10 mm or less, More preferably, it is 1 mm or less which forms a micro reaction field. More preferably, it is 10 micrometers-1 mm, Most preferably, it is 20-300 micrometers.

  A typical example of a reaction apparatus having a channel (channel) having a particularly preferable microscale size of the present invention is a “microreactor”. Reference is made to W. Ehrfeld et al., "Microreactor" 1Ed (2000) WILEY-VCH.

  The general microreactor is provided with a plurality of microchannels having an equivalent diameter of several μm to several hundreds of μm when the cross section is converted into a circle, and a mixing space connected to these microchannels. In such a microreactor, a plurality of solutions are introduced into a mixing space through a plurality of microchannels, thereby mixing the plurality of solutions or causing a chemical reaction with the mixing.

  Next, the main points in which the reaction by the microreactor is different from the batch method using a tank or the like will be described. Liquid-phase chemical reactions and two-phase liquid-phase chemical reactions generally occur when molecules meet at the interface of the reaction solution. The area of the interface increases and the reaction efficiency increases significantly. In addition, the diffusion time of the molecule itself is proportional to the square of the distance. This means that as the scale is reduced, the reaction proceeds more easily due to the diffusion of the molecules without active mixing of the reaction solution, and the reaction tends to occur. In microspaces, the Reynolds number (the dimensionless number that characterizes the flow) is small, so the flow is dominated by laminar flow, and the molecules that exist in each solution at the interface where the solutions are in a laminar flow state. Exchange occurs, and the migrated molecules cause precipitation and reaction.

  When a microreactor having such characteristics is used, the reaction time and temperature between solutions can be precisely controlled as compared with a conventional batch system using a large volume tank or the like as a reaction field. In the case of the batch method, the reaction proceeds at the reaction contact surface at the initial stage of mixing, particularly between solutions with a high reaction rate, and the primary product generated by the reaction between the solutions continues to be reacted in the vessel. Therefore, there is a possibility that the product becomes non-uniform, or the crystal of the product grows more than necessary in the mixing container and becomes coarse. On the other hand, according to the microreactor, the solution continuously circulates with almost no stagnation in the mixing container. Therefore, while the primary product generated by the reaction between the solutions stays in the mixing container, it continues. It is possible to prevent the reaction from occurring, and it is possible to take out a pure primary product that has been difficult to remove in the past, and it is difficult to cause aggregation and coarsening of crystals in the mixing vessel.

  In addition, when a small amount of chemical substances produced by an experimental production facility is manufactured (scaled up) in a large amount by a large-scale production facility, a large-scale batch method is conventionally used. It took a lot of labor and time to obtain reproducibility at the manufacturing equipment, but this was achieved by parallelizing (numbering up) the production lines using microrear coolers according to the required production volume. There is a possibility that labor and time for obtaining such reproducibility can be greatly reduced.

  A method for producing a laminar flow channel that can be used in the method for producing an organic pigment fine particle dispersion of the present invention will be described below. When the flow path has a size of 1 mm or more, it can be manufactured relatively easily by using a normal machining technique. However, when the size is 1 mm or less, particularly 500 μm or less, the manufacturing becomes extremely difficult. In many cases, micro-sized flow paths (micro flow paths) are produced on a solid substrate using a microfabrication technique. The substrate material may be anything as long as it is a stable material that does not easily corrode. For example, metal (for example, stainless steel, hastelloy (Ni—Fe alloy), nickel, aluminum, silver, gold, platinum, tantalum, or titanium), glass, plastic, silicone, Teflon (registered trademark), or ceramics.

  Representative examples of microfabrication techniques for producing microchannels include LIGA (Roentgen-Lithography Galvanik Abforming) technology using X-ray lithography, high aspect ratio photo using EPON SU-8 (trade name). Lithography method, micro electric discharge machining method (μ-EDM (Micro Electro Discharge Machining)), deep RIE (Reactive Ion Etching) silicon high aspect ratio processing method, Hot Emboss processing method, stereolithography method, laser processing method, ion beam Machining methods, and mechanical micro-cutting methods using micro tools made of hard materials such as diamond. These techniques may be used alone or in combination. Preferred microfabrication techniques are LIGA technology using X-ray lithography, high aspect ratio photolithography using EPON SU-8, micro electrical discharge machining (μ-EDM), and mechanical micro-cutting. In recent years, the application of fine injection molding technology to engineering plastics has been studied.

  Joining techniques are often used when producing microchannels. The usual bonding techniques are roughly divided into solid phase bonding and liquid phase bonding, and the commonly used bonding methods are pressure bonding and diffusion bonding as solid phase bonding, welding, eutectic bonding, soldering as liquid phase bonding, Adhesion or the like is a typical joining method. In addition, during assembly, a highly precise bonding method that maintains dimensional accuracy without deteriorating material due to high temperature heating or destruction of micro structures such as flow paths due to large deformation is desirable. There are bonding, anodic bonding, surface activation bonding, direct bonding using hydrogen bonding, bonding using HF aqueous solution, Au-Si eutectic bonding, void-free bonding, and the like.

  The microchannel is not limited to a microchannel manufactured on a solid substrate using a microfabrication technique, and may be various types of fused silica capillary tubes having an inner diameter of several μm to several hundred μm that can be obtained. Various silicon tubes, fluororesin tubes, stainless steel tubes, PEEK tubes (polyether ether ketone tubes) with an inner diameter of several μm to several hundreds of μm that are commercially available for high-performance liquid chromatographs and gas chromatographs are also used. Is possible.

  So far, microreactors have been reported on devices aimed at improving reaction efficiency. For example, JP 2003-210960, JP 2003-210963, JP 2003-210959, JP 2005-46650, JP 2005-46651, JP 2005-46652, JP 2005-288254 are micromixers and microreactors. In the method for producing an organic pigment fine particle dispersion according to the present invention, the above-mentioned microdevice can also be used.

  The microchannel may be surface-treated according to the purpose. In particular, when an aqueous solution is manipulated, surface treatment is important because adsorption of the sample to glass or silicon may be a problem. It would be desirable to achieve fluid control within a micro-sized channel without incorporating moving parts that require complex fabrication processes. For example, it is possible to create a hydrophilic region and a hydrophobic region by surface treatment in the flow path, and manipulate the fluid by utilizing the difference in surface tension acting on the boundary. As a method for surface treatment of glass or silicon, hydrophobic or hydrophilic surface treatment using a silane coupling agent is frequently used.

  In order to introduce and mix reagents and samples into the flow path, a fluid control function is required. In particular, since the behavior of the fluid in the microchannel has a property different from that of the macroscale, a control method suitable for the microscale must be considered. The fluid control method includes a continuous flow method and a liquid droplet (liquid plug) method in terms of form classification, and an electric drive method and a pressure drive method in terms of drive force classification.

  These methods are described in detail below. The most widely used form for handling fluid is the continuous flow system. In continuous flow type fluid control, the entire microchannel is generally filled with fluid, and the entire fluid is generally driven by a pressure source such as a syringe pump prepared outside. This method has a great advantage that a control system can be realized with a relatively simple setup, although it is difficult to have a large dead volume.

  As a method different from the continuous flow method, there is a droplet (liquid plug) method. In this system, droplets partitioned by air are moved in the reactor or in a flow path leading to the reactor, and each droplet is driven by air pressure. At that time, a vent structure that allows the air between the droplet and the channel wall or between the droplets to escape to the outside as needed, and a valve structure that keeps the pressure in the branched channel independent of other parts Etc. need to be prepared inside the reactor system. Further, in order to control the pressure difference and operate the droplet, it is necessary to construct a pressure control system including a pressure source and a switching valve outside. In this way, the droplet system makes the device configuration and the reactor structure somewhat complicated, but it can be operated in multiple stages, such as operating several droplets individually and sequentially performing several reactions. The degree of freedom of configuration increases.

As a driving method for fluid control, an electric driving method is used in which an electroosmotic flow is generated by applying a high voltage to both ends of a flow path (channel) and fluid is moved by this, and pressure is applied to the fluid using a pressure source outside. In general, a pressure driving method of moving by applying a pressure is widely used. The difference between the two is that, for example, the behavior of the fluid is a flat distribution when the flow velocity profile is electrically driven in the cross section of the flow path, whereas the center of the flow path is It is known that the wall portion is fast and has a slow distribution, and the electric drive method is more suitable for the purpose of moving the sample plug while maintaining the shape thereof. When the electric drive method is used, the flow path needs to be filled with a fluid, so it must be in the form of a continuous flow method, but the fluid can be manipulated by electrical control. Therefore, for example, a relatively complicated process of creating a temporal concentration gradient by changing the mixing ratio of two kinds of solutions continuously is realized. In the case of the pressure drive system, there is almost no influence on the substrate because control is possible regardless of the electrical properties of the fluid, and secondary effects such as heat generation and electrolysis do not need to be considered. The application range is wide. On the other hand, it is necessary to automate complicated processes such as the necessity of preparing a pressure source outside and the change of the response characteristics of the operation according to the size of the dead volume of the pressure system.
The method used as the fluid control method is appropriately selected according to the purpose, but is preferably a continuous flow type pressure driving method.

  The temperature control in the flow path may be controlled by placing the entire apparatus having the flow path in a temperature-controlled container, or a heater structure such as a metal resistance wire or polysilicon is built in the apparatus for heating. This may be used for cooling, and the cooling may be performed by natural cooling. For temperature sensing, when using a metal resistance wire, it is preferable to create another resistance wire that is the same as the heater, and to detect the temperature based on the change in the resistance value. When using polysilicon, Detection is preferably performed using a thermocouple. Moreover, you may heat and cool from the outside by making a Peltier device contact a flow path. Which method is used is selected in accordance with the application and the material of the flow path body.

  When the fine particles are deposited in the flow process in the flow path, the reaction time can be controlled by the time spent in the flow path. The residence time is determined by the length of the flow path and the introduction speed of the reaction solution when the equivalent diameter is constant. Although there is no restriction | limiting in particular in the length of a flow path, Preferably they are 1 mm or more and 10 m or less, More preferably, they are 5 mm or more and 10 m or less, Especially preferably, they are 10 mm or more and 5 m or less.

  In the method for producing the organic pigment fine particle dispersion of the present invention, the number of flow paths used is not particularly limited and may be determined as appropriate, and may be one, but if necessary, multiple flow paths may be arranged in parallel ( Numbering up) and the processing amount can be increased.

  A reaction apparatus preferably used in the method for producing the organic pigment fine particle dispersion of the present invention is shown in FIG. However, the present invention is not limited to these.

  1-1 is explanatory drawing of the reactor (10) which has a Y-shaped channel, FIG. 1-2 is sectional drawing of the II line | wire. 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 trapezoidal shape or a shape close to a rectangle. When the channel width / depth (especially C, H) is made in a micro size, the solution injected from the introduction port 11 and the introduction port 12 by a pump or the like passes through the introduction channel 13a or the introduction channel 13b. Then, they contact at the fluid confluence 13d, form a stable laminar flow, and flow through the reaction channel 13c. During the laminar flow, the solutes contained in the laminar flows are mixed or reacted by molecular diffusion at the interface between the laminar flows. In some cases, a solute that is very slowly diffusing does not cause diffusive mixing between laminar flows and mixes only after reaching the outlet 14. When the two solutions to be injected are easily mixed in the flask, if the flow path length F is long, the flow of liquid 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 solutions naturally flow as laminar flows and reach the outlet 14.

  FIG. 2-1 is an explanatory view of a reaction apparatus (20) having a cylindrical tube-type flow path provided with a flow path inserted on one side, and FIG. 2-2 is a cross-sectional view of the apparatus taken along line IIa-IIa. FIG. 2-3 is a sectional view taken along line IIb-IIb of the apparatus. The shape of the cross section perpendicular to the length direction of the flow path is a circle or a shape close thereto. When the diameter (D, E) of the cylindrical tube is a micro size, the solution injected by a pump or the like from the introduction port 21 and the introduction port 22 contacts at the fluid confluence 23d through the introduction channel 23a and the introduction channel 23b. Then, a stable cylindrical laminar flow is formed and flows through the reaction channel 23c. In the same way as the apparatus of FIG. 1-1, the solutes contained in each laminar flow are mixed or reacted by molecular diffusion at the interface between the laminar flows while flowing as a cylindrical laminar flow. Compared with the device shown in FIG. 1-1 above, the present device having a cylindrical channel has a larger contact interface between the two liquids, and further, there is no portion where the contact interface contacts the device wall surface. The feature is that there is no crystal growth from the contact portion with the wall surface, such as when it is generated by reaction, and the possibility of blocking the flow path is low.

  FIGS. 3-1 and 4 are modifications of the apparatus of FIGS. 1-1 and 2-1 so that when the two liquid flows reach the outlet in a laminar flow, they can be separated. 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 50 shown in FIG. 5 includes two divided supply channels 51A and 51B which are branched from one supply channel 51 for supplying the solution A so that the solution A can be divided into two. In addition, one supply channel 52 that does not divide the solution B and a micro channel 53 that performs the reaction between the solution A and the solution B are formed so as to communicate with each other in one merging region 54. It is. The divided supply channels 51A and 51B, the supply channel 52, and the microchannel 53 are arranged at equal intervals of 90 ° around the merging region 54 in substantially the same plane. That is, the central axes (one-dot chain lines) of the flow paths 51A, 51B, 52, and 53 intersect in a cross shape (intersection angle α = 90 °) in the merge region 54. In FIG. 5, only the supply channel 51 for the solution A having a larger supply amount than the solution B is divided, but the supply channel 52 for the solution B may also be divided into a plurality. Further, the crossing angle α of the flow paths 51A, 51B, 52, 53 arranged around the merging region 54 is not limited to 90 ° and can be set as appropriate. In addition, the number of divisions of the supply channels 51 and 52 is not particularly limited, but if the number is too large, the structure of the microreactor device 50 becomes complicated, so 2 to 10 is preferable, and 2 to 5 is more preferable. preferable.

  FIG. 6 is another embodiment of the planar microreactor device 50 of FIG. 5, and the crossing angle β formed by the central axes of the divided supply flow paths 61A and 61B with respect to the central axis of the supply flow path 62 is as shown in FIG. It is formed at 45 ° smaller than 90 °. Further, the crossing angle α formed by the central axis of the micro flow path 63 with respect to the central axis of the divided supply flow paths 61A and 61B is set to 135 °.

  FIG. 7 shows still another aspect of the planar microreactor apparatus of FIG. 5, in which the central axis of the divided supply channels 71A and 71B in which the solution A flows with respect to the central axis of the supply channel 72 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 73 with respect to the central axis of the divided supply flow paths 71A and 71B is 45 °. The crossing angles α and β of the supply channel 72, the divided supply channels 71A and 71B, and the microchannel 73 can be set as appropriate, but the cross-sectional areas in the thickness direction of all the solutions B and A that have joined together The crossing angles α and β are preferably set so that S1> S2 is satisfied, where S1 is S1 and the radial cross-sectional area of the microchannel 73 is S2. This is because the contact area between the solutions 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. 8 is an example of a three-dimensional microreactor device 80 to which the organic pigment fine particle production method of the present invention is applied, and is an exploded perspective view showing a state in which three parts constituting the microreactor device 80 are disassembled. FIG. The three-dimensional microreactor apparatus 80 is mainly composed of a supply block 81, a merge block 82, and a reaction block 83 each having a cylindrical shape. In order to assemble the microreactor apparatus 80, the cylindrical blocks 81, 82, and 83 are arranged in a cylindrical shape by aligning the side surfaces with each other in this order. , 83 are integrally fastened with bolts and nuts.

  Two annular grooves 84 and 85 are formed concentrically on the side surface 83 of the supply block 81 that faces the merging block 82. When the microreactor device 80 is assembled, the two annular grooves 86, 85 forms a ring-shaped channel through which the solution B and the solution A respectively flow. And the through-holes 88 and 87 which reach the outer side annular groove 86 and the inner side annular groove 85 from the opposite side surface 94 which does not oppose the confluence | merging block 82 of the supply block 81 are formed, respectively. Of these two through holes 88, 87, a supply means (pump, connection tube, etc.) for supplying the solution A is connected to the through hole 88 communicating with the outer annular groove 86, and communicates with the inner annular groove 85. A supply means (a pump, a connection tube, etc.) for supplying the solution B is connected to the through-hole 87. In FIG. 8, the solution A is allowed to flow through the outer annular groove 86 and the solution B is allowed to flow into the inner annular groove 85.

  A circular confluence hole 90 is formed at the center of the side surface 89 of the confluence block 82 facing the reaction block 83, and four long radial grooves 91, 91... And four short radial shapes are formed radially from the confluence hole 90. Grooves 92, 92... Are alternately drilled. These merging holes 90 and the radial grooves 91 and 92 form a circular space serving as the merging region 90 and a radial flow path through which the solutions A and B flow when the microreactor device 80 is assembled. Further, among the eight radial grooves 91 and 92, through holes 95, 95... Are formed in the thickness direction of the merge block 82 from the tip of the long radial groove 91, and these through holes 95 are formed in the supply block 81. The outer annular groove 86 is communicated with the aforementioned outer annular groove 86. Similarly, through holes 96, 96... Are formed in the thickness direction of the merging block 82 from the tips of the short radial grooves 92, and these through holes 96 communicate with an inner annular groove 85 formed in the supply block 81. .

Further, at the center of the reaction block 83, one through hole 93 communicating with the merging hole 90 in the thickness direction of the reaction block 83 is formed, and this through hole 93 becomes a micro flow path.
As a result, the solution A flows through the supply flow path constituted by the through-hole of the supply block 81 → the outer annular groove 86 → the through-hole 95 of the confluence block 82 → the long radiation groove 91 and is divided into four divided flows. It reaches an area (merging hole 90). On the other hand, the solution B flows through the supply flow path constituted by the through-hole 87 of the supply block 81 → the inner annular groove 85 → the through-hole 96 of the confluence block 82 → the short radiating groove 92 and is divided into four divided flows. (Merge hole 90). After the divided flow of the solution A and the divided flow of the solution B merge with their respective kinetic energy in the merge region, the flow direction is changed by 90 ° and flows into the microchannel.

  The organic pigment used in the method for producing the organic pigment fine particle dispersion of the present invention is not limited in terms of 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.
The organic solvent used in the method for producing the organic pigment fine particle dispersion of the present invention may be one kind, two kinds or more, or a solid solution thereof, or a combination of an organic pigment and an inorganic pigment. It may be.

  The organic pigment solution used in the method for producing an organic pigment fine particle dispersion of the present invention is preferably one in which an organic pigment is uniformly dissolved, and the method is not particularly limited, but is dissolved as an acidic or alkaline solution. Is preferred. 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.

Examples of the base used in the case of alkaline dissolution include inorganic bases such as sodium hydroxide, potassium hydroxide, calcium hydroxide, or barium hydroxide, or trialkylamine, diazabicycloundecene (DBU), metal Organic bases such as alkoxide (NaOCH ₃ , KOC ₂ H ₅ ) can be mentioned.

  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 1.0 to 100 molar equivalents relative to the pigment, more preferably 5.0 to 100 molar equivalents, and even more preferably 20 to 100 molar equivalents.

  Acids used for acid dissolution include inorganic acids such as sulfuric acid, hydrochloric acid, or phosphoric acid, or organic acids such as acetic acid, trifluoroacetic acid, oxalic acid, methanesulfonic acid, or 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 case of an inorganic acid or an organic acid, it is preferably 3 to 500 molar equivalents, more preferably 10 to 500 molar equivalents, and particularly preferably 30 to 200 molar equivalents with respect to the pigment.

  The solvent for preparing the organic pigment solution is an amide solvent or a sulfur-containing solvent in the case of alkali, and a carboxylic acid solvent, a sulfur solvent or a sulfonic acid solvent in the case of acidity, more preferably Is a sulfur-containing solvent when alkaline, and a sulfonic acid solvent when acidic. Particularly preferred is dimethyl sulfoxide (DMSO) when alkaline, and methanesulfonic acid when acidic.

  Next, the aqueous medium will be described. In the present invention, the aqueous medium refers to water alone or a mixed solvent of water and an organic solvent soluble in water. The organic solvent is, for example, laminar flow when water alone is insufficient to uniformly dissolve the pigment or dispersant, or when water alone is insufficient to obtain the viscosity necessary to flow through the flow path. When it is necessary for the formation of the organic pigment, it is preferably used. In many cases, the organic pigment or the like can be uniformly dissolved by adding a water-soluble organic solvent.

  Examples of the solvent for adding an organic solvent to an aqueous medium include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6. -Polyhydric alcohol solvents such as hexanetriol, acetylene glycol derivatives, glycerin, or trimethylolpropane, ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, or triethylene glycol monoethyl (or Lower monoalkyl ether solvents of polyhydric alcohols such as butyl) ether, ethylene glycol dimethyl ether (monoglyme), diethylene glycol dimethyl ether ( ), Polyether solvents such as triethylene glycol dimethyl ether (triglyme), dimethylformamide, dimethylacetamide, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, urea, Alternatively, an amide solvent such as tetramethylurea, a sulfur-containing solvent such as sulfolane, dimethyl sulfoxide, or 3-sulfolene, a polyfunctional solvent such as diacetone alcohol or diethanolamine, acetic acid, maleic acid, docosahexaenoic acid, trichloroacetic acid, or Examples thereof include carboxylic acid solvents such as trifluoroacetic acid, and sulfonic acid solvents such as methanesulfonic acid or trifluorosulfonic acid. Two or more of these solvents may be mixed and used.

  The mixing ratio of water and the organic solvent is not particularly limited as long as it is a ratio suitable for uniform dissolution. Preferably, in the case of alkaline, water / organic solvent = 0.05 to 10 (mass ratio). When an inorganic acid is used in the acidic case, it is preferable to use sulfuric acid alone, for example, without using an organic solvent. When an organic acid is used, the organic acid itself is an organic solvent, and a plurality of acids are mixed or water is added in order to adjust viscosity and solubility. Preferably, water / organic solvent (organic acid) = 0.005 to 0.1 (mass ratio).

  In the method for producing the organic pigment fine particle dispersion of the present invention, when the organic pigment solution and the aqueous medium are contact-mixed using the flow channel, it is preferable to add the uniformly dissolved solution to the flow channel. When the suspension 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.

Next, the hydrogen ion index (pH) will be described. The hydrogen ion index (pH) is a common logarithm of the reciprocal of the hydrogen ion concentration (molar concentration), and is sometimes called the hydrogen index. The hydrogen ion concentration is the concentration of hydrogen ions H ⁺ in the solution, and means the number of moles of hydrogen ions present in 1 L of solution. Since the hydrogen ion concentration varies within a very wide range, it is usually expressed using the hydrogen ion index (pH). For example, pure water contains ^10-7 moles of hydrogen ions at 1 atmosphere and 25 ° C., so its pH is 7 and neutral. An aqueous solution with pH <7 is acidic, and an aqueous solution with pH> 7 is alkaline. As a method for measuring the pH value, there are a potentiometric method and a colorimetric method.

  In the method for producing an organic pigment fine particle dispersion of the present invention, when an organic pigment solution and an aqueous medium are contact-mixed using a flow path, the hydrogen ion index (pH) is changed in the process of flowing through the flow path, and the pigment Fine particles can be produced, the method of which has a different inlet from the inlet of the homogeneous solution of organic pigment, for example at least two inlets as shown in FIG. 1-1 or FIG. A uniform solution of an organic pigment is introduced into the inlet 11 in FIG. 1-1 or the inlet 21 in FIG. 2-1, and the inlet 12 in FIG. Alternatively, neutral, acidic or alkaline water, or an aqueous solution in which a dispersant is dissolved therein is introduced into the inlet 22 of FIG. 2-1, and both liquids are brought into contact with each other in the flow path 13c or 23c, thereby including an organic pigment. Hydrogen ion concentration of the solution, ie water Ion exponent (pH) can be changed in the direction of the neutral (pH 7). When the equivalent diameter of the channel is microscale, the Reynolds number is small, so a stable laminar flow (cylindrical laminar flow in Fig. 2-1) is formed, and water and ions diffuse through the stable interface between the two liquid layers. It can move and gradually change the hydrogen ion exponent (pH) of the solution containing the organic pigment in the neutral direction. Since the pigment becomes difficult to dissolve in an aqueous medium when it is low alkaline or acidic, it can be gradually precipitated as fine particles as the hydrogen ion index (pH) of the solution containing the organic pigment changes in the neutral direction.

  The change in the hydrogen ion index (pH) is generally a change within the range of pH 16.0 to 5.0, preferably pH 16.0 when producing pigment fine particles from a pigment dissolved in an alkaline aqueous medium. To 10.0 in the range. When producing pigment fine particles from a pigment dissolved in an acidic aqueous medium, the change is generally in the range of pH 1.5 to 9.0, preferably in the range of pH 1.5 to 4.0. It is. The width of the change depends on the value of the hydrogen ion exponent (pH) of the organic pigment solution, but it may be sufficient to encourage the precipitation of the organic pigment.

  Since the pigment fine particles generated in the microscale channel do not diffuse and flow to the outlet while being contained in one laminar flow, the flow having the outlet designed as shown in FIG. 3-1 or FIG. When a road device is used, a laminar flow containing organic pigment fine particles can be separated. When this method is used, a concentrated pigment dispersion can be obtained, and at the same time, the water-soluble organic solvent, alkaline or acidic water used to prepare the uniform solution, and excess dispersant can be removed. . Moreover, it can be avoided that the two liquids are finally mixed so that the crystals are coarsened or the pigment crystals are altered.

  The reaction temperature when producing the pigment fine particles is desirably within the range where the solvent does not coagulate or vaporize, but is preferably -20 to 90 ° C, more preferably 0 to 50 ° C. Especially preferably, it is 5-15 degreeC.

The fluid velocity (flow rate) in the flow path is preferably 0.1 mL to 300 L / hr, more preferably 0.2 mL to 30 L / hr, still more preferably 0.5 mL to 15 L / hr, and 1.0 mL to 6 L / hr. hr is particularly preferred.
In the present invention, the concentration range of the substrate (organic pigment and its reaction components) is usually 0.5 to 20% by mass, preferably 1.0 to 10% by mass.

  The production method of the present invention includes a step of using one or more polymerizable compounds and polymerizing them. In the present invention, the polymerizable compound is a compound that generates a covalent bond using a thermal decomposition of an initiator, light irradiation, or the like as a trigger to give a high molecular weight body having a repeating unit. As the polymerizable compound, any of water-soluble and water-insoluble polymerizable compounds can be used, and it is not particularly limited as long as it can be dispersed together with the organic pigment. A surfactant having a polymerizable group may be used as the polymerizable compound. The polymerizable surfactant will be described later. The timing of containing the polymerizable compound is not particularly limited, but it is preferably contained in at least one of the organic pigment solution and the aqueous medium before mixing them.

  In the organic pigment fine particle dispersion or the organic pigment fine particles produced by the production method of the present invention, it is preferable that a polymer of a polymerizable compound is fixed to the pigment fine particles. In the present invention, “immobilization” refers to a state in which all (or part of) the polymerizable compound contained is in contact with the pigment fine particles alone (or in a copolymerized state). At this time, the polymer may be present either on the surface of the pigment fine particles or inside the pigment fine particles, as long as all (or part of) the polymer is in contact with the pigment fine particles. Adhesion is preferably performed so as not to be detached even by movement in the dispersion. Here, the polymer means a compound produced as a result of polymerization of two or more molecules of the polymerizable compound, and it is not necessary that all the polymerizable compounds on the fine particles are involved in the polymerization reaction. It may remain.

  In the production method of the present invention, it is preferable to use one or more polymerizable compounds represented by the following general formula (1) or (2) as the polymerizable compound. These compounds have a preferred degree of polymerizability in order to obtain the desired organic pigment fine particles. At this time, if the reactivity of the polymerizable compound is too low, excessive polymerization conditions are required, which may adversely affect the pigment fine particles (eg, aggregation). On the other hand, if a polymerizable compound that is too reactive is used, Problems arise in the storage stability of the previous solution.

一般式（１）又は（２）において、Ｒ^１〜Ｒ^７はそれぞれ独立して水素原子または置換基を表す。Ｒ^１〜Ｒ^４、Ｒ^５〜Ｒ^７はそれぞれ互いに結合して環を形成していてもよい。
ｍおよびｎは０または正の整数を表す。

In General Formula (1) or (2), R ^{1 to} R ⁷ each independently represent a hydrogen atom or a substituent. R ^{1 to} R ⁴ and R ^{5 to} R ⁷ may be bonded to each other to form a ring.
m and n represent 0 or a positive integer.

The compound represented by the general formula (1) will be described in more detail.
R ¹ and R ² represent a hydrogen atom or a substituent. The substituent is preferably an alkyl group, an aryl group, an acyl group, an aryloxycarbonyl group, an alkoxycarbonyl group, a silyl group, or the like. Especially, a hydrogen atom, an alkyl group (for example, methyl, ethyl, isopropyl etc. are mentioned, C1-C10 is preferable, More preferably, it is 1-6), An aryl group (For example, phenyl, p-chlorophenyl etc. are mentioned). , Preferably 6 to 10 carbon atoms, more preferably 6 to 8), and acyl groups (for example, acetyl, benzoyl and the like), preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms. R ¹ and R ² may combine with each other to form a ring. When forming a ring, it is preferably a 5-membered ring or a 6-membered ring, more preferably a pyrrolidone ring (pyrrolidinone ring), a pyrrolidine ring, a pyrrole ring, a succinimide, a piperidine ring, a piperidone ring, or a piperidinedione ring. It may have a group or may be benzo-fused, and particularly preferably a pyrrolidone ring.

R ³ and R ⁴ represent a hydrogen atom or a substituent. Preferable specific examples of the substituent include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom), an alkyl group, and an aryl group. R ³ and R ⁴ are more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.
m represents 0 or a positive integer, preferably 0 or 1, and particularly preferably m = 0.

The combination of R ^{1 to} R ⁴ and m is preferably a case where R ¹ and R ² both represent an alkyl group, an aryl group, and an acyl group, R ³ is a hydrogen atom, and m = 0. Preferably, R ¹ and R ² form a —COCH ₂ CH ₂ CH ₂ — group to form a ring, R ³ is a hydrogen atom, and m = 0 (ie, N-vinylpyrrolidone).

The compound represented by the general formula (2) will be described in detail.
R ⁵ represents a hydrogen atom or a substituent. Preferable specific examples of the substituent include the same groups as the examples of R ¹ and R ² described above, and particularly preferably include a hydrogen atom, an alkyl group (for example, methyl, ethyl, isopropyl, etc.). 1-10 are preferred, more preferably 1-6), aryl groups (for example, phenyl, p-chlorophenyl, etc.) are mentioned, 6-10 carbon atoms are preferred, more preferably 6-8), acyl groups (for example, acetyl) , Benzoyl and the like, preferably having 1 to 10 carbon atoms, more preferably 1 to 6), and particularly preferably an alkyl group having 1 to 6 carbon atoms. R ⁶ and R ⁷ represent a hydrogen atom or a substituent. Preferable specific examples of the substituent include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom), an alkyl group, and an aryl group. R ³ and R ⁴ are more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom. n represents 0 or a positive integer, preferably 0 or 1, and particularly preferably n = 0.

  Specific examples of the polymerizable compound represented by the general formula (1) that can be preferably used in the present invention will be given below, but the present invention is not limited to these specific examples.

  Specific examples of the polymerizable compound represented by the general formula (2) that can be preferably used in the present invention will be given below, but the present invention is not limited to these specific examples.

  In the method for producing an organic pigment fine particle dispersion of the present invention, a dispersant may be further added in the organic pigment solution or / and in the aqueous medium. The dispersant has the function of (i) quickly adsorbing on the surface of the pigment that has been deposited to form fine pigment particles, and (ii) preventing these particles from aggregating again. In the method for producing an organic pigment fine particle dispersion of the present invention, an anionic, cationic, amphoteric, nonionic or pigmentary low molecular or high molecular dispersant can be used as a dispersant. These dispersants can be used alone or in 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 anionic dispersants (anionic surfactants) include N-acyl-N-alkyl taurine salts, fatty acid salts, alkyl sulfate esters, alkyl benzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphorus Examples include acid ester salts, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl sulfate ester salts, and the like. Of these, N-acyl-N-alkyltaurine salts are preferred. As the N-acyl-N-alkyltaurine salt, those described in JP-A-3-273067 are preferable. These anionic dispersants can be used alone or in combination of two or more.

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

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

  Nonionic dispersants (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, Examples thereof include glycerin fatty acid esters. Of these, polyoxyethylene alkylaryl ether is preferable. These nonionic dispersants can be used alone or in combination of two or more.

  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.

  Specifically, as the polymer dispersant, 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 butyralized product, vinyl pyrrolidone-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, acrylate ester-acrylate copolymer, acrylate ester Methacrylate copolymer, methacrylate ester-acrylate copolymer, methacrylate ester-methacrylate copolymer, styrene-itaconate copolymer, itaconate-itaconate copolymer, vinyl Examples thereof include naphthalene-acrylate copolymer, vinyl naphthalene-methacrylate copolymer, vinyl naphthalene-itaconate copolymer, cellulose derivative, starch derivative and the like. In addition, natural polymers such as alginate, gelatin, albumin, casein, gum arabic, tonganto gum and lignin sulfonate can also be used. Of these, polyvinylpyrrolidone is preferable. These polymers can be used alone or in combination of two or more.

In the production method of the present invention, a polymerizable surfactant (also called a reactive surfactant, a reactive emulsifier, etc.) having a hydrophilic part, a hydrophobic part, and a polymerizable part in the molecule is used as a polymerization compound. Can be preferable. 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 the organic pigment fine particle 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 are commercially available from Co., Ltd., etc., described in “Cutting-edge Technology of Fine Particles / Powder, Chapter 1, Fine Particle Design Using Reactive Emulsifiers, pp23-31”, 2000 CMC Co., Ltd. And the like.

  As the polymerizable surfactant, a compound represented by the general formula (3) or (4) is preferable.

In the general formula (3), R ⁸ represents an alkyl group or an aryl group (that is, having an allyl ether moiety as a polymerizable moiety). In R ⁸ , hydrophilic sites (for example, carboxylic acid, sulfuric monoester, sulfonic acid, sulfinic acid, or salts thereof, quaternary ammonium, hydroxy group, amino group, etc.) that contribute to dispersibility and hydrophobic sites (for example, An alkyl group having 8 or more carbon atoms or an aryl group, and a fluorine-containing alkyl).
In the general formula (4), R ^{9 to} R ¹¹ represent any one of a hydrogen atom, an alkyl group, and an aryl group, and R ^{12 to} R ¹⁶ represent a hydrogen atom on the benzene ring or an arbitrary substituent (that is, polymerizable). It has a styryl moiety as a moiety). R ^{9 to} R ¹¹ are preferably a hydrogen atom or a methyl group, and particularly preferably all are hydrogen atoms and only one methyl group and the remaining two are hydrogen atoms. This compound has a hydrophilic part (for example, carboxylic acid, sulfuric monoester, sulfonic acid, sulfinic acid, or a salt thereof, quaternary ammonium, hydroxy group, amino group, etc.) and a hydrophobic part (for example, carbon number) that contribute to dispersibility. 8 or more alkyl groups or aryl groups, fluorine-containing alkyl, etc.). These sites may be present in any of R ^{9 to} R ¹⁶ , but are preferably contained in R ^{12 to} R ¹⁶ on the benzene ring.

  When a polymerizable surfactant is used, it is preferably used in a combination capable of copolymerizing the polymerizable compound represented by the general formula (1) or (2) and the polymerizable surfactant. By copolymerizing, the surfactant is also immobilized on the fine particles, and an organic pigment fine particle dispersion having better storage stability and dispersion stability can be obtained. The ratio of the polymerizable compound and the polymerizable surfactant is not particularly limited, but is preferably in the range of 1:10 to 10: 1 by molar ratio, and particularly preferably 1: 3 to 3: 1. .

  Specific examples of the polymerizable surfactant that can be used in the present invention are described below, but the present invention is not limited thereto.

In the production method of the present invention, when a polymerizable compound is polymerized, a high molecular polymerization initiator and a low molecular polymerization initiator are used in combination. The high molecular polymerization initiator used in the present invention refers to those having a number average molecular weight of 2,000 to 500,000. The polymer polymerization initiator preferably has a number average molecular weight of 2,000 to 300,000, particularly preferably 5,000 to 100,000. Moreover, the low molecular weight polymerization initiator used in the present invention refers to those having a molecular weight of 70 to 1,000. The low molecular weight polymerization initiator preferably has a molecular weight of 70 to 500, particularly preferably 100 to 400.
The polymerization mechanism is not particularly limited as long as it can be polymerized in the organic pigment fine particle dispersion, but a method of generating radicals using a polymerization initiator and polymerizing is preferable, and the trigger for starting polymerization is heat, light, super It is preferable to use sound waves, microwaves, etc., and it is preferable to generate radicals by cleavage with heat. Although there is no particular limitation on the chemical structure of the polymerization initiator, it is preferable that at least one of the high-molecular polymerization initiator and the low-molecular polymerization initiator is a compound having an azo group (—N═N—). More preferably, the agent and the low molecular weight polymerization initiator are both compounds having an azo group.

The structure of the polymer polymerization initiator that can be preferably used in the present invention is not particularly limited, but it is preferable to use a compound having an azo group (—N═N—). Specific examples of the polymer polymerization initiator having an azo group include VPE series (azo initiator having a polyethylene unit) and VPS series (azo initiator having a polydimethylsiloxane unit) manufactured by Wako Pure Chemical Industries, Ltd. (These are described on the website of Wako Pure Chemical Industries, Ltd. www.wako-chem.co.jp). Among them, a polymer polymerization initiator having an azo group and further having a polyethyleneoxy group as a repeating unit (specific example: VPE series manufactured by Wako Pure Chemical Industries, Ltd.) is preferable, has an azo group, and further has polyethyleneoxy A polymer polymerization initiator having a group as a repeating unit and a number average molecular weight of 5,000 to 100,000 (specific example: VPE-0201 manufactured by Wako Pure Chemical Industries, Ltd. (number average molecular weight 1.5 10,000 to 30,000) is particularly preferred.
The structure of the low molecular weight polymerization initiator used in the present invention is not particularly limited, but a compound having an azo group (—N═N—) is preferred. As the low-molecular polymerization initiator having an azo group, a compound represented by the following general formula (5) is more preferable.

General formula (5)
R ₁ —N═N—R ₂

In the formula, R ₁ and R ₂ each independently represents a monovalent group selected from the group consisting of an alkyl group which may be substituted with a substituent, an aryl group, and —CONH ₂ . R ₁ and R ₂ are each independently preferably an alkyl group having 3 to 20 carbon atoms which may be substituted with a substituent. Moreover, the low molecular polymerization initiator whose 10-hour half-life temperature is 40 to 110 degreeC (preferably 50 to 90 degreeC) is preferable.
Specific examples of the low molecular weight polymerization initiator preferably used in the present invention include 2,2′-azobisisobutyronitrile (hereinafter also referred to as “AIBN”, molecular weight 164.21), 2,2-azobis-2. -Methylbutyronitrile (molecular weight 192.26), 2,2'-azobis (2-amidinopropane) dihydrochloride (molecular weight 271.19), 2,2'-azobis [2- (2-imidazoline-2- Yl) propane] (molecular weight 250.35) and the like. In addition, persulfates having no azo group (for example, ammonium persulfate (molecular weight 228.20), potassium persulfate (molecular weight 270.32), etc.) and peroxides (for example, dibenzoyl peroxide (molecular weight 242.23), etc.) It is also possible to use.

  Although the addition amount of the polymerization initiator is not particularly limited, the polymer polymerization initiator is preferably 0.1 to 30% by mass, more preferably 1 to 20% by mass, and particularly preferably 2 to the total amount of the polymerizable compound. The low molecular weight polymerization initiator is preferably 0.01 to 2.0 molar equivalents, more preferably 0.02 to 1.0 molar equivalents, particularly preferably the low molecular weight polymerization initiator. 0.05 to 0.5 molar equivalent. The ratio of the high molecular weight polymerization initiator and the low molecular weight polymerization initiator is not particularly limited, but it is preferable to use the high molecular weight polymerization initiator and the low molecular weight polymerization initiator in a weight ratio range of 100: 1 to 1: 100. The range of 20: 1 to 1: 5 is more preferable.

  In the method for producing an organic pigment fine particle dispersion of the present invention, various inorganic or organic functional additives may be allowed to coexist in the dispersion regardless of whether they are copolymerized. Although the time which contains a functional additive is not specifically limited, For example, the case where it adds to at least one of an organic pigment solution and an aqueous medium is mentioned preferably. The functional additive is not particularly limited as long as it does not hinder the precipitation of fine particles and the stabilization of the dispersion. For example, a metal sequestering agent, a bactericidal agent, an antifungal agent, a fragrance, an ultraviolet absorber, an antioxidant, a surface tension adjusting agent. , Water-soluble resins, pH adjusters, urea and the like.

  In the method for producing an organic pigment fine particle dispersion according to the present invention, the organic pigment is precipitated as fine particles and the polymerizable compound in the dispersion is polymerized as it is, so that extremely high dispersion stability can be realized in the pigment dispersion. . This effect is considered as follows. Since the polymerizable compound is present in the mixed liquid obtained by precipitating the pigment in the dissolved state and finely divided, the polymerizable compound is adsorbed integrally with the precipitated fine particles, and the fine particles are efficiently surrounded by the polymerizable compound without gaps. By subjecting this to a polymerization reaction as it is, the polymerizable compound can be surely polymerized so as to densely enclose the entire surface of the pigment fine particles, and can be firmly and uniformly fixed and prevented from detaching. As described above, in the present invention, by using the polymerizable compound, both the size control function at the time of build-up and the subsequent encapsulation function can be exhibited. Thereby, the finely dispersed pigment fine particles can be encapsulated as they are, and high dispersion stability and storage stability can be imparted to nano-sized pigment fine particles having a uniform particle diameter. In particular, when a polymerizable surfactant is used as the polymerizable compound, and the polymerizable compound represented by the general formula (1) or (2) of the present invention is used in combination, these are copolymerized, Because it adsorbs more strongly and surrounds the fine particles, the dispersion stability is further increased.

In the method for producing the organic pigment fine particle dispersion of the present invention, the timing and method for polymerizing the polymerizable compound are not particularly limited. For example, the following two processes are shown as examples. It may be performed during or after (1), during or after step (2), or both.
(1) A process of mixing a solution in which an organic pigment is dissolved and an aqueous medium.
(2) A process of concentrating and purifying the dispersion after mixing.

Similarly, the timing and method of addition of the polymerization initiator are not particularly limited. For example, the following four embodiments may be used, or any of them may be used in combination. However, the polymer polymerization initiator is preferably according to (1) or (2).
(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 polymerization reaction temperature can be selected according to the type of the polymerization initiator, and is preferably 40 ° C to 100 ° C, more preferably 50 ° C to 90 ° C, and particularly preferably 50 ° C to 80 ° C. The polymerization reaction time can be 1 to 12 hours, although it depends on the polymerizable compound used, its concentration, and the reaction temperature of the polymerization initiator. Further, it is preferable to perform a substitution treatment with an inert gas such as argon or nitrogen before the polymerization treatment, and it is preferable to place it in an inert gas atmosphere during the polymerization reaction.

For the purpose of increasing the fastness of pigments, additives such as UV absorbers, antioxidants, fragrances, fungicides, surface tension regulators, water-soluble resins, bactericides, pH regulators, and urea may be used in combination. Good. 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.
In order to adjust the degree of polymerization (molecular weight), various chain transfer agents (for example, catechols, alcohols, thiols, mercaptans) may be used.

  The content of the polymerizable compound (the total amount when the polymerizable compound represented by the general formula (1) or (2) and the polymerizable surfactant are used together) in the mixed solution is the uniform dispersibility of the pigment. In order to further improve the storage stability, it is preferably in the range of 0.1 to 1000 parts by weight, more preferably in the range of 1 to 500 parts by weight, particularly preferably 100 parts by weight of the pigment. It is the range of 10-250 mass parts. If the amount is less than 0.1 parts by mass, the dispersion stability of the organic pigment fine particles may not be improved. The preferable content range of the dispersant is the same as that of the polymerizable compound.

Next, the organic pigment fine particles produced by the method for producing the organic pigment fine particle dispersion of the present invention will be described.
There is a method for expressing the average size of the population by quantifying in the particle measurement method, but the most commonly used is the mode diameter indicating the maximum value of the distribution and the median diameter corresponding to the median value of the integral distribution curve. , And various average diameters (length average, area average, weight average, number average, volume average, etc.). The particle size of the organic pigment fine particles produced by the production method of the present invention is arbitrary as long as the flow path is not blocked, but the mode diameter is preferably 1 μm or less. Preferably it is 3 nm-800 nm, Most preferably, it is 5 nm-500 nm. Further, in the case of a nanometer-size fine particle dispersion required for high-quality inkjet inks, the mode diameter of the organic pigment fine particles is preferably 80 nm or less, more preferably 50 nm or less, Especially preferably, it is 30 nm or less.

Uniform particle size means that the particle size of the fine particles is uniform, that is, not only the size of the contained particles is uniform, but also the chemical composition and crystal structure within the particle do not vary between particles. However, it is an important factor that determines the performance of particles. In particular, in the case of ultrafine particles having a particle size of nanometer, importance is attached as a factor governing the characteristics of the particles. The method for producing the organic pigment fine particle dispersion of the present invention can not only make fine particles having a small particle diameter but also control the size and make the sizes uniform. Although the arithmetic standard deviation value is used as an index indicating that the sizes are uniform, the arithmetic standard deviation value of the pigment fine particles produced by the method for producing the organic pigment fine particle dispersion of the present invention is preferably 130 nm or less, Particularly preferably, it is 80 nm or less, and the peak of the particle size distribution can be sharpened. The arithmetic standard deviation value is a method of obtaining the standard deviation by regarding the particle size distribution as a normal distribution, and is a value obtained by dividing the value obtained by subtracting the 16% particle size from the 84% particle size of the integrated distribution by 2.
Further, a value (Mv / Mn) obtained by dividing the volume average particle diameter Mv by the number average particle diameter Mn may be expressed as an index of monodispersity. In the present invention, unless otherwise specified, the monodispersity of the fine particles is described above. Mv / Mn is indicated by the value of Mv / Mn, and the smaller the value is, the better the monodispersity is. The organic pigment fine particles of the present invention preferably have a value of 1.80 or less, and 1.60 or less. Is more preferable, and particularly preferably 1.40 or less. The volume average particle diameter Mv and the number average particle diameter Mn can be measured by, for example, a dynamic light scattering method.
Furthermore, the organic pigment fine particles of the present invention preferably have high stability, and can be represented by a rate of change in particle size due to storage treatment as an index indicating the stability. For example, the change in the volume average particle size Mv described above It can be expressed as a rate. 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.

  In the method for producing an organic pigment fine particle dispersion according to the present invention, examples of the solvent used include the aforementioned organic solvents, dispersants, surfactants, polymerizable compounds, additives, or water, and combinations thereof. It is done. Further, for example, a water-soluble organic solvent added to the ink composition and other components may be further added as necessary. As these solvent components, for example, components of a pigment dispersant as described in JP-A-2002-194263 and JP-A-2003-26972 can be applied.

The fluids to be mixed may be fluids that are mixed with each other or fluids that are not mixed. Mixed fluids are solutions using the same or relatively similar organic solvent, or solutions using a highly polar organic solvent such as methanol and water. Non-mixed fluids are hexane. And a solution using a low polarity solvent such as methanol and a solution using a high polarity solvent such as methanol.
When gases such as air, nitrogen, oxygen, argon, and helium are used, they can be dissolved in the reaction fluid or introduced as a gas into the flow path, and the method of introducing as a gas is preferred.

  According to the method for producing an organic pigment fine particle dispersion of the present invention, an organic pigment can be precipitated as fine particles, and a polymerization reaction of a polymerizable compound can be performed as it is to form and fix a polymerizable film on the fine particles. That is, there is no need to pulverize the fine particles or to separate the produced fine particles and switch the process equipment. This is nothing but the introduction of the continuous production method in the flow, and has the merit of greatly reducing physical loss such as quality stabilization, process stabilization, time and energy, and transfer.

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 before and / or after the polymerization treatment. Furthermore, depending on the purpose of use, solvents (wetting agents, etc.), additives (metal sequestering agents, bactericides, fungicides, fragrances, ultraviolet absorbers, antioxidants, surface tension regulators, water-soluble resins, pH regulators) , Urea, etc.) may be added to adjust the liquid properties.
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.

  The present invention will be described below in more detail based on examples, but the present invention is not limited to these examples.

  The pH shown in the examples was measured with a glass electrode type hydrogen ion concentration meter HM-40V (measurement range pH 0 to 14) manufactured by Toa Denpa Kogyo Co., Ltd. The particle size distribution was measured with a Microtrac UPA150 manufactured by Nikkiso Co., Ltd. The viscosity was measured using an AMVn Automated Microvisometer (Falling Ball Capillary Viscometer) manufactured by Anton Parr.

Example 1
Pigment and Yellow 128 (CROMOPHTAL YELLOW 8GNP, manufactured by Ciba Specialty Chemicals Co., Ltd.) 3.0 g, dimethyl sulfoxide 45.5 mL, 28% sodium methoxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) 2.49 mL, 2.4 g of Aqualon KH-10 (Daiichi Kogyo Seiyaku Co., Ltd.), N-vinylpyrrolidone (Compound 1-1, manufactured by Wako Pure Chemical Industries, Ltd., purified by distillation under reduced pressure) 6 g, 0.15 g of polyvinylpyrrolidone K30 (manufactured by Tokyo Chemical Industry Co., Ltd.), VPE-0201 (manufactured by Wako Pure Chemical Industries, Ltd., number average molecular weight 15,000 to 30,000) 0.50 g, azobis 0.11 g of isobutyronitrile (abbreviated as AIBN, manufactured by Wako Pure Chemical Industries, Ltd., molecular weight 164.21, 10 hour half-life temperature 65 ° C.) dissolved at room temperature It was (IE solution). The pH of the IE solution exceeded the measurement limit (pH 14) and could not be measured. Distilled water was used as the IIE solution. Impurities such as dust were removed by passing these through a 0.45 μm microfilter (manufactured by Sartorius). As the microreactor device, the three-dimensional microreactor device of FIG. 8 having the following number of divisions (number of flow paths) and the like was used.

(I) Number of supply flow paths (n): Divided into 5 for each of the two types of reaction solutions (a total of 10 flow paths merge. In addition, the apparatus of FIG. It is a device to do.)
(Ii) width (W) of supply flow paths 91 and 92: 400 μm each
(Iii) Depth (H) of supply flow paths 91 and 92: 400 μm each
(Iv) Diameter (D) of merging region 90 ... 800 μm
(V) Microchannel 93 diameter (R): 800 μm
(Vi) Intersection angle between the central axes of the supply flow paths 91 and 92 and the micro flow path 93 in the merging region 90 ... 90 °
(Vii) Material of the device: stainless steel (SUS304)
(Viii) Flow path machining method: Performed by micro electric discharge machining, and the sealing method of the three parts of the supply block 81, the merging block 82, and the reaction block 83 was performed by metal surface sealing by mirror polishing. Two Teflon (registered trademark) tubes having a length of 50 cm and an equivalent diameter of 1 mm were connected to the two inlets using a connector, and syringes containing IE solution and IIE solution were connected to the ends of the tubes and set in a pump. A Teflon (registered trademark) tube having a length of 1.5 m and an equivalent diameter of 2 mm was connected to the outlet of the connector. The IE solution was delivered at a delivery rate of 150 mL / min, and the IIE solution was delivered at a delivery rate of 600 mL / min. A pigment yellow 128 dispersion was obtained from the tip of the tube outlet, which was collected and used as sample 1a. Sample 1a had a pH of about 13.2, a volume average particle diameter Mv of 26.1 nm, and a ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersity, was 1.47.

Further, this liquid was degassed by bubbling with nitrogen gas and then heated at 80 ° C. for 5 hours to obtain Sample 1b. The volume average particle diameter Mv of the sample 1b was 26.4 nm, and the ratio of volume average particle diameter Mv / number average particle diameter Mn, which is an index of monodispersibility, was 1.50.
Next, each of the sample 1a and the sample 1b was purified by adding ultrapure water (Advantech Toyo Co., Ltd., UHP-62K, molecular weight cut off 50,000) while maintaining the liquid volume, followed by 60 ° C. For 100 hours. The change rate of the volume average particle size of the sample 1a is 4.3% (change rate of the volume average particle size: the volume average particle size Mv after the heat storage treatment is divided by the volume average particle size Mv before the heat storage treatment, and 1 is obtained. Subtracted value), the rate of change of the volume average particle diameter of Sample 1b was 2.3%. From this result, it is understood that the stability is improved by the polymerization treatment.

  Further, the sample 1b was purified and concentrated while removing the filtrate with an ultrafiltration device (manufactured by Advantech Toyo Co., Ltd., UHP-62K, molecular weight cut off 50,000), and then the dispersion was adjusted to 5.0% by mass. The viscosity of the liquid is 3.8 mPa.s. s. Then, when the heat storage process was carried out at 60 degreeC for 100 hours and also for 240 hours, both viscosity was 3.8 mPa.s. No change was seen in s. On the other hand, when the sample 1a was purified and concentrated in the same manner, the viscosity was 7.9 mPa.s. s. Furthermore, when the heat storage process was similarly performed at 60 degreeC, sedimentation was already seen at the time of a 100-hour storage. Thus, the excellent viscosity stability that can maintain a constant viscosity even in the heat storage treatment is to ensure long-term storage stability, for example, when used as an inkjet ink, and is more suitable as an ink. It is shown that.

(Example 2)
Sample 2a was obtained in the same manner as Sample 1a except that the amount of VPE-0201 used in Example 1 was changed to half 0.25 g. The pH of sample 2a was about 13.2. This was degassed by nitrogen bubbling and then heated at 80 ° C. for 5 hours to obtain Sample 2b. For this sample 2b, the volume average particle diameter Mv, the ratio of volume average particle diameter Mv / number average particle diameter Mn, and the concentration after purification and concentration using an ultrafiltration device are the same as in sample 1b of Example 1 and the measurement method. The viscosity of the dispersion liquid adjusted to 5.0% by mass, the viscosity after heat storage treatment at 60 ° C. for 100 hours and 240 hours, and the presence or absence of sedimentation are shown in Table 1.

(Example 3)
N-vinyl pyrrolidone (compound 1-1) used in Example 1 was changed to vinyl benzyl ether having the same mass (compound 2-2, manufactured by Wako Pure Chemical Industries, Ltd., purified by distillation under reduced pressure). The polymerization initiator was changed from AIBN to 0.13 g of azobismethyl ibutyronitrile (manufactured by Wako Pure Chemical Industries, Ltd., trade name V-59, molecular weight 192.26, 10 hour half-life temperature 67 ° C.). Other than that, Sample 3a was obtained in the same manner as Sample 1a. The pH of sample 3a was about 13.0. This was deaerated by nitrogen bubbling and then heated at 80 ° C. for 5 hours to obtain Sample 3b. About this sample 3b, the same kind of test was performed by the same operation and measurement method as sample 1b of Example 1, and the results are shown in Table 1.

Example 4
Sample 4b was obtained in the same manner as Sample 1b of Example 1 except that Aqualon KH-10 was not used. About this sample 4b, the same kind of test was done by the same operation and measurement method as sample 1b of Example 1, and the results are shown in Table 1.

(Comparative Example 1)
Except for the polymeric initiator VPE-0201 from Example 1, double the amount of AIBN. Sample 5b was obtained in the same manner as Sample 1b except that the amount was 22 g. About this sample 5b, the same kind of test was done by the same operation and measurement method as sample 1b of Example 1, and the results are shown in Table 1.

(Comparative Example 2)
Sample 6b was obtained in the same manner as Sample 1b except that the polymer initiator VPE-0201 used in Example 1 was tripled to 1.5 g, and AIBN was excluded. About this sample 6b, the same kind of test was done by the same operation and measurement method as sample 1b of Example 1, and the results are shown in Table 1.

(Comparative Example 3)
Sample 6-2b was obtained in the same manner as in sample 1b except that the polymerization initiator AIBN was removed from Example 1. About this sample 6-2b, the same kind of test was done by the same operation and measurement method as sample 1b of Example 1, and the results are shown in Table 1.

(Example 5)
Sample 7b was obtained in the same manner as Sample 1b except that Pigment Yellow 128 was changed to 3.0 g of Pigment Red 254 (CROMOPHTAL RED 2030, manufactured by Ciba Specialty Chemicals). For this sample 7b, the same kind of test was performed by the same operation and measurement method as sample 1b of Example 1, and the results are shown in Table 2.

(Comparative Examples 4A and 4B)
Pigment Yellow 128 was changed to 3.0 g of Pigment Red 254 (CROMOPHTAL RED 2030, manufactured by Ciba Specialty Chemicals), and a high molecular weight polymerization initiator and a low molecular weight polymerization initiator were each used in the amounts shown in Table 2 alone. Other than that, Samples 8b and 9b were obtained in the same manner as Sample 1b. For these samples 8b and 9b, the same kind of test was performed by the same operation and measurement method as the sample 1b of Example 1, and the results are shown in Table 2.

(Example 6)
Pigment Yellow 128 was changed to 3.0 g of Pigment Blue 16 (Tokyo Kasei Kogyo Co., Ltd., phthalocyanine disodium), and Sample 10b was obtained in the same manner as Sample 1b. This sample 10b was subjected to the same type of test and measurement method as in sample 1b of Example 1, and the results are shown in Table 2.

(Comparative Example 5 and Comparative Example 6)
Pigment Yellow 128 was changed to Pigment Blue 16 (Tokyo Kasei Kogyo Co., Ltd., phthalocyanine disodium) 3.0 g, and the amounts of the high molecular weight polymerization initiator and the low molecular weight polymerization initiator listed in Table 2 were used alone. Other than that, Samples 11b and 12b were obtained in the same manner as Sample 1b. The samples 11b and 12b were subjected to the same kind of test and operation as in the sample 1b of Example 1, and the results are shown in Table 2.

The high molecular weight polymerization initiator is necessary for obtaining a dispersion having a small viscosity change with time of heating (see Comparative Examples 1 and 2, Comparative Examples 4A and 4B, Comparative Examples 5 and 6), but only a large amount thereof. Use is expensive and unsuitable for industrial scale production (see Comparative Examples 2 and 3). Moreover, high monodispersibility may not be obtained depending on the pigment type only with the polymer polymerization initiator (Comparative Example 4A, Comparative Example 5).
On the other hand, according to the method for producing an organic pigment fine particle dispersion of the present invention, it is possible to achieve both production of high-performance fine particles and cost reduction by using a high-molecular polymerization initiator and a low-molecular polymerization initiator in combination. (See each example).

It is explanatory drawing of the reaction apparatus which has a Y-shaped channel on one side. It is sectional drawing of the II line | wire of FIGS. 1-1. It is explanatory drawing of the reaction apparatus which has a cylindrical tube type flow path provided with the flow path penetrated to one side. It is sectional drawing of the IIa-IIa line | wire of FIGS. It is sectional drawing of the IIb-IIb line | wire of FIGS. It is explanatory drawing of the reactor which has a Y-shaped channel on both sides. It is sectional drawing of the III-III line of FIGS. It is explanatory drawing of the reaction apparatus which has the cylindrical tube type flow path which provided the flow path penetrated on both sides It is explanatory drawing explaining the aspect of a planar type microreactor apparatus. It is explanatory drawing explaining another aspect of a planar type microreactor apparatus. It is explanatory drawing explaining another aspect of a planar microreactor apparatus. It is a disassembled perspective view which shows the state which the solid-type microreactor apparatus decomposed | disassembled.

Explanation of symbols

10, 20, 30, 40 Reactor body 11, 12, 21, 22, 31, 32, 41, 42 Inlet 13, 33 Channel 13a, 13b, 23a, 23b, 33a, 33b, 43a, 43b Inlet channel 13c, 23c, 33c, 43c Reaction flow path 13d, 23d, 33d, 43d Fluid confluence 33e, 43e Fluid diversion point 33f, 33g, 43f, 43g Discharge flow path 14, 24, 34, 35, 44, 45 Discharge port 50 , 60, 70, 80 Microreactor devices 51, 52, 61, 62, 71, 72 Solution supply channels 51A, 61A, 71A Split supply channels 53, 63, 73 Microchannels 54, 64, 74 Merge region 81 Supply block 82 Junction block 83 Reaction block 86 Outer annular groove 85 Inner annular groove 87, 88 Through hole 90 in supply block Flow area)
91 Long radial groove 92 Short radial groove 95, 96 Through-hole 93 of confluence block Through-hole of reaction block (micro flow path)

Claims (18)

  When a solution in which an organic pigment is dissolved and an aqueous medium are mixed to form a mixed solution, fine particles of the organic pigment are generated in the mixed solution, and the polymerizable compound contained in the mixed solution is polymerized. A method for producing an organic pigment fine particle dispersion, wherein the polymerizable compound is polymerized in the presence of one or more polymerization initiators and one or more low-molecular polymerization initiators.   The solution in which the organic pigment is dissolved and the aqueous medium are circulated through a channel having an equivalent diameter of 1 mm or less to form a liquid flow, and both are brought into contact with each other to be mixed. A method for producing an organic pigment fine particle dispersion.   The method for producing an organic pigment fine particle dispersion according to claim 1, wherein at least one of the high molecular polymerization initiator and the low molecular polymerization initiator has an azo group (—N═N—).   The organic pigment according to any one of claims 1 to 3, wherein at least one of the organic pigment solution and the aqueous medium contains at least one polymer polymerization initiator before mixing the two liquids. A method for producing a fine particle dispersion.   The method for producing an organic pigment fine particle dispersion according to any one of claims 1 to 4, wherein the polymer of the polymerizable compound is fixed to pigment fine particles by polymerizing the polymerizable compound. The method for producing an organic pigment fine particle dispersion according to any one of claims 1 to 5, comprising at least one polymerizable compound represented by the following general formula (1) or (2). .

[In General Formula (1), R ^{1 to} R ⁴ each independently represents a hydrogen atom or a substituent. At this time, R ^{1 to} R ⁴ may be bonded to each other to form a ring. m represents 0 or a positive integer. In General Formula (2), R ^{5 to} R ⁷ each independently represent a hydrogen atom or a substituent. At this time, R ^{5 to} R ⁷ may be bonded to each other to form a ring. n represents 0 or a positive integer. ]   In the said General formula (1), m is 0 or 1, The manufacturing method of the organic pigment fine particle dispersion liquid of Claim 6 characterized by the above-mentioned.   The method for producing an organic pigment fine particle dispersion according to any one of claims 1 to 7, wherein the polymerizable compound is N-vinylpyrrolidone.   In the said General formula (2), n is 0 or 1, The manufacturing method of the organic pigment fine particle dispersion liquid of Claim 6 characterized by the above-mentioned.   The method for producing an organic pigment fine particle dispersion liquid according to any one of claims 1 to 9, wherein one or more polymerizable surfactants are contained in the mixed liquid as a polymerizable compound.   11. The mixture according to claim 6, wherein at least one compound represented by the general formula (1) or (2) and at least one polymerizable surfactant are contained in the mixed solution. The manufacturing method of the organic pigment fine particle dispersion of any one. The method for producing an organic pigment fine particle dispersion according to claim 10 or 11, wherein the polymerizable surfactant is a compound represented by the following general formula (3) or (4).

[In General Formula (3), R ⁸ represents an alkyl group or an aryl group. In General Formula (4), R ^{9 to} R ¹¹ each independently represent any of a hydrogen atom, an alkyl group, and an aryl group, and R ^{12 to} R ¹⁶ each independently represent a hydrogen atom or a substituent. ]   The method for producing an organic pigment fine particle dispersion according to any one of claims 1 to 12, wherein the organic pigment solution is alkaline.   The method of producing an organic pigment fine particle dispersion according to claim 1, wherein the hydrogen ion index (pH) is changed in the course of mixing the organic pigment solution and the aqueous medium.   The organic pigment according to any one of claims 1 to 14, wherein a solution in which an organic pigment is dissolved and an aqueous medium are circulated as a laminar flow in a channel, and are brought into contact with each other and mixed in the laminar flow process. A method for producing a fine particle dispersion.   16. The method for producing an organic pigment fine particle dispersion according to claim 15, wherein the flow path is a micro reaction field.   The method for producing an organic pigment fine particle dispersion according to claim 16, wherein the flow path has an equivalent diameter of 10 mm or less. Organic pigment fine particles obtained by the production method according to claim 1, wherein the mode diameter is 1 μm or less.

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