JP2006342316A - Process for concentrating organic particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process for efficiently concentrating organic particles prepared by reprecipitation, to provide particles obtained by the process, to provide a concentration process causing change of neither particle size nor monodisperse property of the organic particles in a concentration step and capable of easily redispersing the organic particles aggregated by condensation, to provide organic particles having fine particle size and high monodisperse property and obtained by the condensation process, and to provide a condensation process hardly causing change of particle size, monodisperse property and the like even when scaleup is put into practice. <P>SOLUTION: The process for concentrating organic particles comprises mixing a solution of an organic material dissolved in a good solvent with a poor solvent for the organic material which poor solvent is compatible with the good solvent so as to form the organic material as crystals having ≤1 μm particle diameter or an association, wherein the solvent of the organic particle dispersion containing the organic particles, or the solvent of a condensed extraction liquid condensing/extracting the organic particles with an extraction solvent, is removed by at least one process selected from centrifugation and heat-drying under reduced pressure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  An object of the present invention is to provide a method for efficiently concentrating organic particles produced by a reprecipitation method, and organic particles obtained thereby. It is another object of the present invention to provide a concentration method in which the particle size and monodispersity of organic particles do not change in the concentration step, and the organic particles aggregated by concentration can be easily redispersed.

In recent years, efforts have been made to reduce the size of particles. In particular, research is being conducted to reduce the size to nanometer size (for example, in the range of 10 to 100 nm), which is difficult to produce by a pulverization method, a precipitation method, or the like. Furthermore, attempts have been made to reduce the size to nanometer size and to obtain particles having high monodispersity (in the present invention, monodispersity means the degree of uniform particle size).
Unlike the larger bulk particles and smaller molecules and atoms, these nanometer-sized microparticles are located in the middle of them, and are unprecedented size regions, which can lead to unexpected new properties. It has been pointed out. In addition, if the monodispersity can be increased, the characteristics can be stabilized. The potential of such nanoparticles is expected in various fields, and research is being actively conducted in a wide range of fields such as biochemistry, new materials, electronic devices, light-emitting display devices, printing, and medicine.
In particular, organic nanoparticles made of an organic compound have a high potential as a functional material because the organic compound itself has diversity. For example, polyimide is used in many fields because it is a chemically and mechanically stable material such as heat resistance, solvent resistance, and mechanical properties, and has excellent electrical insulation. The use of polyimide in fine particles is expanding its new use due to the combination of polyimide characteristics and shape. For example, as a proposed technique for using finely divided polyimide, it has been proposed to use an additive for powder toner for image formation (Patent Document 1).

Also, regarding organic pigments among organic nanoparticles, for example, paints, printing inks, electrophotographic toners, ink-jet inks, color filters, etc. can be cited as applications, and now important in life. It has become a compound. Among these, high performance is required, and pigments for inkjet inks and color filter pigments are particularly important for practical use.
Conventionally, dyes have been used for coloring materials for ink jet inks, but there are problems in terms of water resistance and light resistance, and pigments have been used to improve them. An image obtained with the pigment ink has an advantage of being excellent in light resistance and water resistance as compared with an image obtained with a dye-based ink. However, it is difficult to increase the monodispersity at a nanometer size that can penetrate into the voids on the paper surface, and there is a problem that the adhesion to paper is poor.
In addition, with the increase in the number of pixels of a digital camera, it is desired to reduce the thickness of color filters used for optical elements such as CCD sensors and display elements. An organic pigment is used for the color filter. However, since the thickness of the filter greatly depends on the particle diameter of the organic pigment, it is desired to produce fine particles having a nanometer size level and being monodispersed and stable.

Regarding the production of organic particles, the gas phase method (a method in which a sample is sublimated in an inert gas atmosphere and the particles are recovered on a substrate), the liquid phase method (for example, a sample dissolved in a good solvent under stirring conditions and temperature). Reprecipitation method to obtain fine particles by injecting into a controlled poor solvent), laser ablation method (method of refining particles by ablating by irradiating laser to sample dispersed in solution), etc. ing. In addition, production examples in which monodispersion with a desired size is attempted by these methods have been reported. (Refer patent documents 2-4 etc.).
Among them, the reprecipitation method is attracting attention as a method for producing organic particles excellent in simplicity and productivity.

In the reprecipitation method, the prepared organic particles are obtained in a state dispersed in a solvent. In order to utilize this industrially, it is necessary to concentrate it to an appropriate concentration or to separate it as fine particles. However, there is not enough research on this. For example, Patent Document 5 discloses a method of adding an evaporation promoting liquid to an organic particle-containing aqueous dispersion and concentrating it by distillation. However, considering that this method is applied to organic particle-containing aqueous dispersions prepared by the reprecipitation method, if the boiling point of the good solvent of the organic material is higher than that of water, only the water will evaporate. There is a concern that the particle size of the organic particles increases during the concentration.
Patent Document 6 discloses a method in which an ionic liquid that does not substantially dissolve in the dispersion medium is added to a dispersion containing fine particles, and the fine particles are concentrated in the ionic liquid. However, this method alone may not sufficiently concentrate the organic particle dispersion to a desired concentration.
Patent Document 7 discloses a production example in which a fine pigment dispersion is concentrated by filtration under reduced pressure, but the particle size is often increased by concentration. Moreover, it is a manufacture example when a manufacturing scale is comparatively small, and when a manufacturing scale is raised, there exists a possibility that a particle size, monodispersibility, and redispersibility cannot be maintained.
Even if desired particles can be prepared in a dispersion by reprecipitation or the like, they cannot be commercialized if the particle size changes or the monodispersibility deteriorates in the concentration and separation / recovery process. Moreover, it cannot be put into practical use because the process requires a great deal of cost.

JP-A-11-237760 Japanese translation of PCT publication No. 2002-092700 JP-A-6-79168 JP 2004-91560 A JP 2004-181312 A JP 2004-292632 A JP 2004-43776 A

  An object of the present invention is to provide a method for efficiently concentrating organic particles produced by a reprecipitation method, and organic particles obtained thereby. Further, the concentration method in which the particle size and monodispersity of the organic particles do not change in the concentration step, and the organic particles aggregated by the concentration can be easily redispersed, and the resulting organic particles having a fine particle size and high monodispersibility. The purpose is to provide particles. Another object of the present invention is to provide a method for concentrating organic particles suitable for industrialization with little change in particle size, monodispersibility and redispersibility even when the concentration step of organic particles is scaled up.

The above problems have been achieved by the following means.
(1) A method of concentrating organic particles formed by mixing a solution of an organic material dissolved in a good solvent and a poor solvent of the organic material compatible with the solvent, and forming the organic material as particles. Organic particles characterized by removing the solvent of the organic particle dispersion containing particles or the solvent of the concentrated extract obtained by concentrating and extracting the organic particles with an extraction solvent by at least one method selected from centrifugation and heating under reduced pressure Concentration method.
(2) The method for producing organic particles according to (1), wherein the number average particle diameter of the organic particles is 1 μm or less.
(3) The poor solvent of the organic material is an aqueous solvent, an alcohol solvent, a ketone solvent, an ether solvent, an ester solvent, or a mixture thereof, described in (1) or (2) To concentrate organic particles.
(4) A good solvent for the organic material is an aqueous solvent, an alcohol solvent, a ketone solvent, an ether solvent, a sulfoxide solvent, an ester solvent, an amide solvent, or a mixture thereof ( The method for concentrating organic particles according to any one of 1) to (3).
(5) The method for concentrating organic particles according to any one of (1) to (4), wherein the extraction solvent is an ester solvent.
(6) The method for concentrating organic particles according to any one of (1) to (5), wherein the organic material is an organic pigment.

According to the organic particle concentration method of the present invention, the organic solvent can be efficiently concentrated by removing the dispersion solvent from the organic particle dispersion prepared by the reprecipitation method. Concentration without increasing the particle size and degrading monodispersity even when the amount of good solvent injected into the poor solvent is increased or the scale of organic particle production is increased during reprecipitation. In addition, the organic particles aggregated by concentration can be easily redispersed, so that highly efficient organic particles can be produced.
The concentrated organic particle paste produced by the concentration method of the present invention and the organic particles obtained therefrom can be used as a suitable inkjet ink or its raw material fine particles, or a color filter coating liquid or its raw material fine particles.

  The present invention relates to an organic particle dispersion or a concentration method of an organic particle concentrated extract obtained by concentrating and extracting organic particles, and the solvent of the organic particle dispersion or concentrated extract is at least one selected from centrifugation and heating under reduced pressure. The present invention relates to a method of concentrating organic particles by removing by a method. Hereinafter, the concentration method of the present invention will be described in detail. The particles formed by the production method of the present invention may be crystalline particles, amorphous particles, or a mixture thereof.

  The organic material used in the organic particle concentration method of the present invention is not particularly limited as long as it can form organic particles by a reprecipitation method. Examples of the organic material include organic pigments, organic dyes, fullerenes, polydiacetylenes, polyimides and other high molecular compounds, aromatic hydrocarbons or aliphatic hydrocarbons (eg, aromatic hydrocarbons or aliphatic hydrocarbons having orientation). Or an aromatic or aliphatic hydrocarbon having a sublimation property), an organic pigment, an organic dye, or a polymer compound is preferable, and an organic pigment is particularly preferable. A combination of these may also be used.

  The organic pigment used in the organic particle concentration method of the present invention is not limited in hue. For example, perylene, perinone, quinacridone, quinacridonequinone, anthraquinone, anthanthrone, benzimidazolone, disazo condensation, disazo, Examples thereof include azo, indanthrone, phthalocyanine, triarylcarbonium, dioxazine, aminoanthraquinone, diketopyrrolopyrrole, thioindigo, isoindoline, isoindolinone, pyranthrone or isoviolanthrone pigments, and mixtures thereof.

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 yellow 150 (C.I. No. 48545), 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), C.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. Pigment Orange 61 (C.I. No. 11295) and the like, isoindolinone pigments such as 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. And isoviolanthrone pigments such as CI Pigment Violet 31 (60010).
In the organic particle concentration method of the present invention, two or more kinds of organic pigments or solid solutions of organic pigments can be used in combination.

  Examples of organic dyes include azo dyes, cyanine dyes, merocyanine dyes, and coumarin dyes. Examples of the polymer compound include polydiacetylene and polyimide.

Regarding the particle size of organic particles, there is a method of expressing the average size of the population by quantifying by a measurement method, but as a common use, the mode diameter indicating the maximum value of the distribution, the median value of the integral distribution curve Median diameter, various average diameters (number average, length average, area average, weight average, volume average, etc.), etc. in the present invention, unless otherwise specified, the particle size is the number average diameter. Say. The particle size of the organic particles (primary particles) contained in the organic particle dispersion used in the organic particle concentration method of the present invention is 500 μm or less, preferably 100 μm or less, and more preferably 10 μm or less. Further, when producing nanometer-sized nanoparticles, the particle size is preferably 1 nm to 1 μm, more preferably 1 to 200 nm, further preferably 2 to 100 nm, and 5 to 80 nm. It is particularly preferred.
In the present invention, the ratio (Mv / Mn) of the volume average particle diameter (Mv) and the number average particle diameter (Mn) is used as an index representing the monodispersity of the particles unless otherwise specified. The monodispersity, that is, Mv / Mn, of particles (primary particles) contained in the organic particle dispersion used in the organic particle concentration method of the present invention is preferably 1.0 to 2.0. More preferably, it is -1.8, and it is especially preferable that it is 1.0-1.5.
Examples of the method for measuring the particle size of organic particles include microscopy, gravimetric method, light scattering method, light blocking method, electrical resistance method, acoustic method, and dynamic light scattering method. Particularly preferred. Examples of the microscope used in the microscopy include, for example, a scanning electron microscope (for example, by drying a dispersion of organic particles on a filter paper, taking a photograph with a scanning electron microscope, and measuring the particles in a photograph with a caliper. Particle diameter can be obtained.), And a transmission electron microscope. Examples of the particle measuring apparatus by the dynamic light scattering method include Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd. and Dynamic Light Scattering Photometer DLS-7000 series manufactured by Otsuka Electronics Co., Ltd.

Next, a method for depositing and forming organic particles will be described.
The solvent used for forming the organic particles by precipitation is a poor solvent for the organic material, and is not particularly limited as long as it is compatible with or uniformly mixed with a good solvent for dissolving the organic material. As a poor solvent for the organic material, the solubility of the organic material is preferably 0.02% by mass or less, and more preferably 0.01% by mass or less. This solubility may be the solubility when dissolved in the presence of an acid or alkali. In addition, the compatibility or uniform mixing property between the good solvent and the poor solvent is preferably such that the solubility of the good solvent in the poor solvent is 30% by mass or more, and more preferably 50% by mass or more.
Examples of the poor solvent include aqueous solvents (for example, water, hydrochloric acid, aqueous sodium hydroxide), alcohol solvents, ketone solvents, ether solvents, aromatic solvents, carbon disulfide, aliphatic solvents, nitriles. Examples thereof include a system solvent, a halogen solvent, an ester solvent, an ionic liquid, a mixed solvent thereof, and the like, and an aqueous solvent, an alcohol solvent, or an ester solvent is preferable.
Examples of the alcohol solvent include methanol, ethanol, isopropyl alcohol, n-propyl alcohol, 1-methoxy-2-propanol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of the ether solvent include dimethyl ether, diethyl ether, tetrahydrofuran and the like. Examples of the aromatic solvent include benzene and toluene. Examples of the aliphatic solvent include hexane. Examples of the nitrile solvent include acetonitrile. Examples of the halogen solvent include dichloromethane, trichloroethylene, and the like. Examples of the ester solvent include ethyl acetate, ethyl lactate, 2- (1-methoxy) propyl acetate and the like. Examples of the ionic liquid include a salt of 1-butyl-3-methylimidazolium and PF ₆ ^— .

Next, a good solvent that dissolves the organic material will be described.
The good solvent is not particularly limited as long as it can dissolve the organic material to be used and is compatible with or uniformly mixed with the poor solvent used in the preparation of the organic particles. The solubility of the organic pigment in a good solvent is such that the solubility of the organic material is preferably 0.2% by mass or more, and more preferably 0.5% by mass or more. This solubility may be the solubility when dissolved in the presence of an acid or alkali. The preferred range of the compatibility or uniform mixing property between the poor solvent and the good solvent is as described above.
Examples of good solvents include aqueous solvents (eg, water, hydrochloric acid, aqueous sodium hydroxide), alcohol solvents, amide solvents, ketone solvents, ether solvents, aromatic solvents, carbon disulfide, and aliphatic solvents. Solvents, nitrile solvents, sulfoxide solvents, halogen solvents, ester solvents, ionic liquids, mixed solvents thereof, and the like, aqueous solvents, alcohol solvents, ester solvents, sulfoxide solvents or amide solvents. Are preferred, aqueous solvents, sulfoxide solvents or amide solvents are more preferred, and sulfoxide solvents or amide solvents are particularly preferred.
Examples of amide solvents include N, N-dimethylformamide, 1-methyl-2-pyrrolidone, 2-pyrrolidinone, 1,3-dimethyl-2-imidazolidinone, 2-pyrrolidinone, ε-caprolactam, formamide, N -Methylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, N-methylpropanamide, hexamethylphosphoric triamide and the like. Examples of the sulfoxide solvent include dimethyl sulfoxide, diethyl sulfoxide, hexamethylene sulfoxide, sulfolane and the like.
Further, the concentration of the organic material solution in which the organic material is dissolved in the good solvent is preferably a saturated concentration of the organic material with respect to the good solvent in the dissolving condition or a range of about 1/100 of this, depending on the organic material used. However, 0.5-12 mass% is preferable, for example.
The conditions for preparing the organic material solution are not particularly limited, and a range from normal pressure to subcritical and supercritical conditions can be selected. The temperature at normal pressure is preferably −10 to 150 ° C., more preferably −5 to 130 ° C., and particularly preferably 0 to 100 ° C.

There are no particular restrictions on the conditions of the poor solvent during the preparation of the organic particles, and a range from normal pressure to subcritical and supercritical conditions can be selected. The temperature at normal pressure is preferably −30 to 100 ° C., more preferably −10 to 60 ° C., and particularly preferably 0 to 30 ° C.
The mixing method of the organic pigment solution and the poor solvent is not particularly limited, but it is preferable to stir one and add the other to it, and it is particularly preferable to add the organic pigment solution to the stirred poor solvent. . A pump or the like may be used for the addition, or it may not be used. Moreover, although addition in a liquid or addition outside a liquid may be sufficient, addition in a liquid is more preferable.
The stirring speed for stirring one is preferably 100 to 10000 rpm, more preferably 150 to 8000 rpm, and particularly preferably 200 to 6000 rpm.
The ratio of the organic material solution to the poor solvent (good solvent / poor solvent) is preferably 1/50 to 2/3 in volume ratio, more preferably 1/40 to 1/2, and particularly preferably 1/20 to 3/8. .
The concentration of the dispersion liquid after the preparation of the organic particles is not particularly limited as long as the organic particles can be dispersed, but the particle is preferably in the range of 10 to 40000 mg, more preferably in the range of 20 to 30000 mg with respect to 1000 ml of the dispersion solvent. And particularly preferably in the range of 50 to 25000 mg.

  In the method for concentrating organic particles of the present invention, a dispersant may be used. For example, an anionic dispersant, a cationic dispersant, an amphoteric dispersant, and a nonionic dispersant may be added.

Next, a method for extracting organic particles will be described.
The extraction solvent used for extraction of the organic particles is not particularly limited as long as it can extract the organic particles in the dispersion, but is not substantially mixed with the dispersion solvent (in the present invention, it is not substantially mixed). Means that the compatibility is small, the dissolution amount is preferably 50% by mass or less, and more preferably 30% by mass or less.) After mixing, it is preferably a solvent that forms an interface when allowed to stand.
The extraction solvent is preferably an ester solvent, an alcohol solvent, an aromatic solvent or an aliphatic solvent, more preferably an ester solvent, an aromatic solvent or an aliphatic solvent, and particularly preferably an ester solvent.
Examples of the ester solvent include 2- (1-methoxy) propyl acetate, ethyl acetate, and ethyl lactate. Examples of the alcohol solvent include n-butanol and isobutanol. Examples of the aromatic solvent include benzene, toluene, xylene and the like. Examples of the aliphatic solvent include n-hexane and cyclohexane. Further, the extraction solvent may be a pure solvent based on the above preferred solvent or a mixed solvent composed of a plurality of solvents.

The amount of the extraction solvent is not particularly limited as long as the organic particles can be extracted, but is preferably smaller than the organic particle dispersion in consideration of concentration and extraction. When this is represented by volume ratio, when the organic particle dispersion is 100, the added extraction solvent is preferably in the range of 1 to 100, more preferably in the range of 10 to 90, and 20 to 80. A range is particularly preferred. If it is too much, it will take a lot of time for concentration, and if it is too little, extraction will be insufficient and particles will remain in the dispersion solvent.
After adding the extraction solvent, it is preferable to stir and mix so as to be in sufficient contact with the dispersion. Conventional methods can be used for stirring and mixing. Although there is no restriction | limiting in particular in the temperature when adding and mixing an extraction solvent, It is preferable that it is 1-100 degreeC, and it is more preferable that it is 5-60 degreeC. Any device may be used for adding and mixing the extraction solvent as long as each step can be preferably performed. For example, a separation funnel type device can be used.

In the organic particle concentration method of the present invention, a preferred embodiment is to concentrate the organic particle dispersion or the extract thereof by centrifugation.
As the centrifuge used, any device may be used as long as it can precipitate the organic particles in the organic particle dispersion and the organic particle concentrated extract. As a centrifuge, for example, in addition to a general-purpose device, a device with a skimming function (a function of sucking the supernatant layer during rotation and discharging it out of the system) or continuous centrifugation for continuously discharging solid matter Machine.
Centrifugation conditions are preferably 50 to 10000, more preferably 100 to 8000, and particularly preferably 150 to 6000 in terms of centrifugal force (a value representing how many times the gravitational acceleration is applied). Although the temperature at the time of centrifugation is based on the solvent seed | species of a dispersion liquid, -10-80 degreeC is preferable, -5-70 degreeC is more preferable, 0-60 degreeC is especially preferable. After concentration by centrifugation, the organic material contained in the supernatant is preferably 15 or less, more preferably 10 or less, when the mass of the organic material contained in the dispersion or the extract before centrifugation is 100. . Moreover, 1-60% is preferable and, as for the organic material density | concentration in the paste-form solid content settled by centrifugation, 2-50% is more preferable.

In the organic particle concentration method of the present invention, another preferred embodiment is to concentrate the organic particle dispersion or the extract thereof under reduced pressure.
The apparatus used for concentration of organic particles by drying under reduced pressure is not particularly limited as long as the solvent of the organic particle dispersion and the organic particle concentrated extract can be evaporated. For example, a general-purpose vacuum dryer and a rotary pump, an apparatus that can be heated and reduced in pressure while stirring the liquid, and an apparatus that can be continuously dried by passing the liquid through a heated and reduced pressure tube.
The heating and drying temperature is preferably 30 to 230 ° C, more preferably 35 to 200 ° C, and particularly preferably 40 to 180 ° C. The pressure during decompression is preferably 100 to 100,000 Pa, more preferably 300 to 90,000 Pa, and particularly preferably 500 to 80,000 Pa. The organic pigment concentration of the paste-like solid content after drying under reduced pressure by heating is preferably 10 to 80%, more preferably 15 to 75% by mass ratio.

According to the organic particle concentration method of the present invention, even if the particles aggregate due to concentration, they can be finely dispersed into primary particles by redispersion by ultrasonic irradiation or the like, and the particle size is preferably 1 It can be set to ˜200 nm, more preferably 2 to 100 nm, and particularly preferably 5 to 80 nm. Further, the Mv / Mn of the re-dispersed particles can be preferably 1.0 to 2.0, more preferably 1.0 to 1.8, and particularly preferably 1.0. -1.5.
Regarding the redispersibility, the particle size of the aggregate of organic particles (hereinafter, this particle size is also referred to as “aggregated particle size”) and the particle size of the primary particles in the aggregate (hereinafter referred to as “primary particle size”). The value can be evaluated by a value obtained by dividing the aggregated particle size by the primary particle size (hereinafter, this value is also referred to as “redispersion index”). According to the organic particle concentration method of the present invention, the redispersion index of the organic particles in the obtained concentrated liquid can be preferably 1.0 to 2.0, more preferably 1.0 to 1. .9. The redispersion index represents the degree of aggregation of the particles. The more the particles are dispersed in a state close to the primary particle size, the smaller the value of the redispersion index becomes and approaches 1.
According to the organic particle concentration method of the present invention, organic particles can be efficiently concentrated from an organic particle dispersion. Regarding the concentration ratio, for example, when the density of the particles in the organic particle dispersion as a raw material is 1, the density in the concentrated organic particle paste is preferably about 100 to 3000 times, more preferably about 500 to 2000 times. be able to.

  According to the method for concentrating organic particles of the present invention, the organic particles can be concentrated with a target particle size regardless of the minute particle size of nanometer size (for example, 10 to 100 nm). For this reason, when it is set as the ink for inkjet, it can be made a clear ink with high optical density, excellent image surface uniformity, and high chroma. Furthermore, when used in a color filter, the optical density is high, the filter surface is excellent in uniformity, the contrast is high, and image noise can be reduced.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited thereto.
The particle diameter of the organic pigment particles was measured as a number average particle diameter of 100 particles by measuring with a scanning electron microscope after drying the dispersion on a filter paper. Further, Mv / Mn as an index of monodispersity was measured using Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd.

(Preparation of dispersion)
[Dispersion (1)]
In order to prepare 1100 ml of an organic pigment particle dispersion having a ratio of pigment solution to poor solvent (good solvent / poor solvent) of 1/10, 530 mg of pigment (Pigment Red 254) and 8 ml of 1 mol / l sodium hydroxide were added to 1-methyl- A pigment solution dissolved in 100 ml of 2-pyrrolidone was prepared. Separately, 1000 ml of water containing 8 ml of 1 mol / l hydrochloric acid was prepared as a poor solvent.
Here, the temperature of the solution was controlled at 1 ° C., and the pigment solution was added to the poor solvent stirred at 500 rpm with a GK-0222-10 type Lamond Stirrer manufactured by Fujisawa Pharmaceutical Co., Ltd. NP-KX-500 type large capacity manufactured by Nippon Seimitsu Chemical An organic pigment particle dispersion was prepared by injecting the entire amount into a poor solvent at a flow rate of 50 ml / min using a non-pulsating pump. This was designated as dispersion (1). The particle size and Mv / Mn immediately after preparation were measured.

[Dispersion (2)]
Further, in order to prepare 1300 ml of an organic pigment particle dispersion having a pigment solution to poor solvent ratio (good solvent / poor solvent) of 3/10, 1590 mg of pigment (Pigment Red 254) and 24 ml of 1 mol / l sodium hydroxide A pigment solution dissolved in 300 ml of methyl-2-pyrrolidone was prepared. Separately, 1000 ml of water containing 24 ml of 1 mol / l hydrochloric acid was prepared as a poor solvent. Here, an organic pigment particle dispersion was prepared in the same manner as in the dispersion (1). This was designated as dispersion (2). The particle size and Mv / Mn immediately after preparation were measured.

[Dispersion (3)]
In order to prepare 3300 ml of an organic pigment particle dispersion having a pigment solution / poor solvent ratio (good solvent / poor solvent) of 1/10, 1590 mg of pigment (Pigment Red 254) and 24 ml of 1 mol / l sodium hydroxide A pigment solution dissolved in 300 ml of methyl-2-pyrrolidone (NMP) was prepared. Separately, 3000 ml of water containing 24 ml of 1 mol / l hydrochloric acid was prepared as a poor solvent. Here, an organic pigment particle dispersion was prepared in the same manner as in the dispersion (1). This was designated as dispersion (3). The particle size and Mv / Mn immediately after preparation were measured.

[Dispersion (4)]
Further, in order to prepare 3900 ml of an organic pigment particle dispersion having a pigment solution / poor solvent ratio (good solvent / poor solvent) of 3/10, 4770 mg of pigment (Pigment Red 254) and 72 ml of 1 mol / l sodium hydroxide were added to 1- A pigment solution dissolved in 900 ml of methyl-2-pyrrolidone was prepared. Separately, 3000 ml of water containing 72 ml of 1 mol / l hydrochloric acid was prepared as a poor solvent. Here, an organic pigment particle dispersion was prepared in the same manner as in the dispersion (1). This was designated as dispersion (4). The particle size and Mv / Mn immediately after preparation were measured by the same method as in the dispersion (1).

[Dispersion (5)]
In order to prepare 9900 ml of an organic pigment particle dispersion having a pigment solution / poor solvent ratio (good solvent / poor solvent) of 1/10, 4770 mg of pigment (Pigment Red 254) and 72 ml of 1 mol / l sodium hydroxide were added to 1- A pigment solution dissolved in 900 ml of methyl-2-pyrrolidone (NMP) was prepared. Separately, 9000 ml of water containing 72 ml of 1 mol / l hydrochloric acid was prepared as a poor solvent. Here, an organic pigment particle dispersion was prepared in the same manner as in the dispersion (1). This was designated as Dispersion (5). The particle size and Mv / Mn immediately after preparation were measured.

[Dispersion (6)]
Further, in order to prepare 11700 ml of an organic pigment particle dispersion having a pigment solution / poor solvent ratio (good solvent / poor solvent) of 3/10, 14310 mg of pigment (Pigment Red 254) and 216 ml of 1 mol / l sodium hydroxide were added to 1- A pigment solution dissolved in 2700 ml of methyl-2-pyrrolidone was prepared. Separately, 9000 ml of water containing 216 ml of 1 mol / l hydrochloric acid was prepared as a poor solvent. Here, an organic pigment particle dispersion was prepared in the same manner as in the dispersion (1). This was designated as Dispersion (6). The particle size and Mv / Mn immediately after preparation were measured.

[Dispersion (7)]
In addition, a pigment solution (300 ml) was prepared by dissolving 150 mmol / L of the pigment (Pigment Red 254) in a solution obtained by mixing dimethylsulfoxide (DMSO) and 8 mol / l-potassium hydroxide aqueous solution at a weight ratio of 6: 1. Separately, 3000 ml of water was prepared as a poor solvent. Here, an organic pigment particle dispersion was prepared in the same manner as in the dispersion (1). This was designated as Dispersion Liquid (7). The particle size and Mv / Mn immediately after preparation were measured.

Example 1
The prepared organic pigment particle dispersions (1) to (7) were each subjected to a high speed centrifugal cooler HIMAC SCR20B manufactured by Hitachi Koki Co., Ltd. at 3500 rpm (2000 times the gravitational acceleration) for 1 hour. Centrifugation was performed, the supernatant was discarded, and the organic pigment particle concentrated pastes (a1) to (a7) of the present invention that had settled were collected. When the pigment content of the paste was measured using an Agilent 8453 type spectrophotometer, the concentrated paste (a1), (a2), (a3), (a4), (a5), (a6), And (a7) were 28, 27, 27, 28, 29, 27, and 30% by mass, respectively.
The primary particle size of the organic pigment particles in the concentrated paste was determined by observation with a scanning electron microscope in the same manner as described above (shown in the section of “Primary particle size after concentration” in each table), and 20 times the pigment weight of water. Was added to the paste, and the agglomerated particle size was measured with Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd., and the redispersion index was determined from the agglomerated particle size and the primary particle size (in each table, the term “redispersion index” Pointing out toungue).
Thereafter, the aggregated pigment particles were dispersed to primary particles by irradiating ultrasonic waves for 1 hour using a Branson model (Model) 200bdc-h 40: 0.8 type ultrasonic homogenizer, and then again Nanotrack UPA manufactured by Nikkiso Co., Ltd. -Mv / Mn was measured using EX150 (shown in the "Mv / Mn after concentration" section in each table).

(Example 2)
The organic pigment particle dispersion liquids (1) to (7) were manufactured by using a vacuum dryer DP-32 type manufactured by Yamato Kagaku Co., and the dispersion liquids (1) and (2) were at 120 ° C. for 10 minutes. 3), (4), and (7) were 120 ° C. for 30 minutes, and the dispersions (5) and (6) were concentrated by drying each paste under reduced pressure at 120 ° C. for 90 minutes, Organic pigment particle concentrated pastes (b1) to (b7) were obtained. When the pigment content of the paste was measured in the same manner as in Example 1, it was 32 for each of the concentrated pastes (b1), (b2), (b3), (b4), (b5), (b6), and (b7). 32, 30, 30, 30, 31, 34 mass%. For the concentrated pastes (b1) to (b7), “primary particle size after concentration”, “Mv / Mn after concentration”, and “redispersion index” were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 7, respectively. Described.

(Example 3)
After preparing the organic pigment particle dispersion liquids (1) to (7), the dispersion liquid (1) is 500 ml, the dispersion liquid (2) is 590 ml, the dispersion liquid (3) is 1500 ml, and the dispersion liquid (4) is 1770 ml. By adding 4500 ml of liquid (5), 5320 ml of dispersion (6), and 1500 ml of 2- (1-methoxy) propyl acetate to dispersion (7) and stirring at 20 ° C. for 10 minutes at 100 rpm, an organic pigment is obtained. The particles were extracted into a 2- (1-methoxy) propyl acetate phase to obtain concentrated extracts (c1) to (c7). The organic pigment particles contained in the dispersion solvent left after the extraction were reduced to approximately 5% by mass or less.
The concentrated extracts (c1) to (c7) were centrifuged under the same conditions as in Example 1 to obtain organic pigment particle concentrated pastes (d1) to (d7). When the pigment content of the paste was measured in the same manner as in Example 1, it was 30 for each of the concentrated pastes (d1), (d2), (d3), (d4), (d5), (d6), and (d7). 29, 28, 29, 27, 27, and 30% by mass. For the concentrated pastes (d1) to (d7), “primary particle size after concentration”, “Mv / Mn after concentration”, and “redispersion index” were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 7, respectively. Described.

Example 4
Organic pigment particle concentrated extracts (c1) to (c7) were prepared in the same manner as in Example 3, and then dried under reduced pressure under the same conditions as in Example 2 to obtain organic pigment particle concentrated pastes (e1) to (e7). ) The pigment content of the paste was measured in the same manner as in Example 1. The dispersions (e1), (e2), (e3), (e4), (e5), (e6), and (e7) were each 36%. 36, 36, 34, 33, 34, 37% by mass. With respect to the concentrated pastes (e1) to (e7), “primary particle size after concentration”, “Mv / Mn after concentration”, and “redispersion index” were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 7, respectively. Described.

(Comparative Example 1)
Organic pigment particle dispersions (1) to (7) were prepared. This was filtered using a FP010 type filter manufactured by Sumitomo Electric Fine Polymer, respectively, to obtain organic pigment particle concentrated pastes (f1) to (f7). The pigment content of the paste was measured in the same manner as in Example 1. The dispersions (f1), (f2), (f3), (f4), (f5), (f6), and (f7) were each 33. 31, 33, 34, 31, 30, 34 mass%. For the concentrated pastes (f1) to (f7), “primary particle size after concentration”, “Mv / Mn after concentration”, and “redispersion index” were measured in the same manner as in Example 1, and the results are shown in Tables 1 to 7, respectively. Described.

(Comparative Example 2)
Organic pigment particle concentrated extracts (c1) to (c7) were prepared in the same manner as in Example 3. The prepared organic pigment particle concentrated extract was filtered by the same method as in Comparative Example 1 to obtain organic pigment particle concentrated pastes (g1) to (g7). When the pigment content of the paste was measured in the same manner as in Example 1, each of the concentrated pastes (g1), (g2), (g3), (g4), (g5), (g6), and (g7) was 34. , 35, 32, 32, 31, 30, 31 mass%. With respect to the concentrated pastes (g1) to (g7), “primary particle size after concentration”, “Mv / Mn after concentration”, and “redispersion index” were measured in the same manner as in Example 1. The results are shown in Tables 1 to 7, respectively.

(Comparative Example 3)
Organic pigment particle dispersions (1) to (7) were prepared. Using a vacuum dryer DP-32 manufactured by Yamato Scientific, the dispersions (1) and (2) were 120 ° C. for 60 minutes, and the dispersions (3), (4) and (7) were 120 ° C. and 180 ° C. The dispersions (6) and (7) were concentrated by drying only by heating under reduced pressure at 120 ° C. for 540 minutes to obtain organic pigment particle concentrated pastes (h1) to (h7). Obtained. The pigment content of the paste was measured in the same manner as in Example 1. The dispersions (h1), (h2), (h3), (h4), (h5), (h6), and (h7) were 28, 27, 25, 26, 25, 25, and 28% by mass. For the concentrated pastes (h1) to (h7), “primary particle size after concentration”, “Mv / Mn after concentration”, and “redispersion index” were measured in the same manner as in Example 1. The results are shown in Tables 1 to 7, respectively.

  Note that the organic pigment particles contained in the dispersions (1) to (7) immediately after the production had a particle size of approximately 20 nm and Mv / Mn 1.4.

By using centrifugal separation or heating under reduced pressure, the organic pigment particles were concentrated without changing the particle size and monodispersity of the organic pigment particles, and an organic pigment particle concentrated paste with good redispersibility was obtained. In addition, when increasing the volume ratio of good solvent to poor solvent (good solvent / poor solvent) and the amount of dispersion to be concentrated, filter filtration concentration and heat drying increase particle size during concentration, monodispersity, and redispersibility. However, there was no significant change in particle size, monodispersibility, and redispersibility in centrifugal concentration or heating under reduced pressure. Increasing the good solvent / poor solvent is important for increasing the efficiency of particle production because the dispersion concentration thereby increases.
According to the concentration method of the present invention, it is possible to concentrate while maintaining the particle size, monodispersibility and redispersibility with a high good solvent / poor solvent, and it is possible to produce organic particles efficiently. In addition, according to the concentration method of the present invention, even when the amount of the dispersion is increased to 3 times or 9 times, the particle size, the monodispersibility, and the redispersibility are not dependent on the scale, and these are maintained. Concentration is possible, and mass production of organic particles becomes possible. The example shown in Table 7 is an example when the pigment solution concentration is increased about 10 times from the example shown in Table 3. In filter filtration, the particle size increases, monodispersity and redispersion with increasing concentration. However, there was no significant change in particle size, monodispersibility, and redispersibility in centrifugal concentration or heating under reduced pressure.
Increasing the concentration of the good solvent is important for increasing the efficiency of particle production because the concentration of the dispersion increases thereby. According to the concentration method of the present invention, it is possible to concentrate at a high solution concentration while maintaining the particle size, monodispersibility and redispersibility, and it becomes possible to produce organic particles efficiently.

Details of the reagents used are as follows.
Reagent Manufacturer -------------------------------------- Pigment Red 254 (Irgafore Red) Chiba Specialty
Chemicals 1-methyl-2-pyrrolidone Wako Pure Chemical Industries dimethyl sulfoxide Wako Pure Chemicals 2- (1-methoxy) propyl acetate Wako Pure Chemicals 1 mol / l Sodium hydroxide aqueous solution Wako Pure Chemicals 1 mol / l Hydrochloric acid aqueous solution Wako Pure Chemical Industries, Ltd. 8 mol / l Potassium hydroxide aqueous solution Wako Pure Chemical Industries, Ltd. ---------------------------- -----------

Claims (6)

  A method of concentrating organic particles formed by mixing a solution of an organic material dissolved in a good solvent and a poor solvent of the organic material compatible with the solvent, and forming the organic material as particles, the method including the organic particles A method for concentrating organic particles, wherein the solvent of the organic particle dispersion or the solvent of the concentrated extract obtained by concentrating and extracting the organic particles with an extraction solvent is removed by at least one method selected from centrifugation and heating under reduced pressure. .   The method for concentrating organic particles according to claim 1, wherein the number average particle diameter of the organic particles is 1 μm or less.   The organic solvent concentration according to claim 1 or 2, wherein the poor solvent of the organic material is an aqueous solvent, an alcohol solvent, a ketone solvent, an ether solvent, an ester solvent, or a mixture thereof. Method.   The good solvent of the organic material is an aqueous solvent, an alcohol solvent, a ketone solvent, an ether solvent, a sulfoxide solvent, an ester solvent, an amide solvent, or a mixture thereof. 4. The method for concentrating organic particles according to any one of 3 above.   The method for concentrating organic particles according to claim 1, wherein the extraction solvent is an ester solvent. The method for concentrating organic particles according to any one of claims 1 to 5, wherein the organic material is an organic pigment.