JP4307481B2 - Method for producing dispersion - Google Patents

Description

The present invention relates to a method for producing a dispersion.

  In aqueous dispersion materials containing functional substances, conventionally, as functional materials, herbicides, pesticides such as insecticides, anticancer agents, antiallergic agents, medicines such as anti-inflammatory agents, and inks having colorants, Color materials such as toner are well known.

  In addition, pigments have been used as color materials contained in ink, toner, and the like. Under these circumstances, a pigment dispersion method using a microjet reactor has been proposed in order to obtain a good pigment dispersion using a pigment.

For example, Patent Document 1 discloses a method of obtaining a pigment suspension by spraying and colliding a solution in which a crude pigment is dissolved in a solvent and a precipitation medium from a nozzle in a housing in a reactor chamber.
JP 2002-155221 A

  In Patent Document 1, since the solution containing the pigment and the precipitation medium are sprayed and mixed in front from the nozzles facing each other, the liquid is scattered in the casing in the chamber.

  In this case, it is conceivable that the scattered liquid or reactant adheres and accumulates on the inner wall of the casing, and is detached from the inner wall of the casing and peels off as time passes.

  Then, there is a possibility that the separated or peeled liquid or the reaction product may cause a secondary reaction with the liquid newly sprayed from the nozzle.

  For this reason, it is not always easy to obtain a homogeneous pigment dispersion stably for a long time by the method disclosed in Japanese Patent Application Laid-Open No. H10-260260.

  The present invention has been made in view of such background art, and provides a method for producing a dispersion that can stably produce a dispersion for a long time by suppressing scattering of liquids to be mixed. It is.

  Further, the present invention provides a pigment ink having excellent dispersibility of pigment particles and showing high gloss on printed matter, using the dispersion obtained by this production method.

The method for producing a dispersion provided by the present invention includes a step of producing a reaction product by reacting at least two kinds of liquids, and a dispersion comprising particles obtained by dispersing the reaction product in a dispersion medium. a manufacturing method,
Preparing a nozzle having an opening diameter of 500 μm or less for discharging the liquid;
Traveling direction was discharged the liquid so as to intersect within the following 120 degrees from one another, and discharge said liquid to then flow together at least two kinds of liquid from the nozzles provided individually is brought into contact with the liquid each other by Rukoto, anda step of generating said reaction product,
One of the two types of liquid is a solution in which the pigment is dissolved, and the other is a solvent that lowers the solubility of the dissolved pigment, and at least one of the two types of liquid contains a dispersant,
The flow rate of the liquid to be discharged is set to a flow rate in which L / S is within a range of 26 to 360, where S (mm ² ) is a nozzle opening area and L (ml / min) is a liquid discharge flow rate. The pigment is precipitated and dispersed in the solvent by contact .

The dispersion provided by the present invention includes a reaction product obtained by reacting at least two kinds of liquids, and a dispersion in which particles made of the reaction product are dispersed in a dispersion medium.
The at least two types of liquids are discharged from nozzles individually provided so that the traveling directions of the discharged liquids intersect each other within a range of 120 degrees or less, and the liquids then flow integrally. It is characterized by including the reaction product produced | generated.

  According to the method of the present invention, it is possible to eliminate the secondary reaction caused by liquid scattering by suppressing the liquid scattering, and to produce a dispersion stably for a long time.

In the production method of the dispersion of the present invention, at least two types of reacting a liquid includes the step of generating a reaction product, the production method of the reaction product particles consisting dispersed in a dispersion medium dispersion There ,
Preparing a nozzle having an opening diameter of 500 μm or less for discharging the liquid;
Traveling direction was discharged the liquid so as to intersect within the following 120 degrees from one another, and discharge said liquid to then flow together at least two kinds of liquid from the nozzles provided individually is brought into contact with the liquid each other by Rukoto, anda step of generating said reaction product,
One of the two types of liquid is a solution in which the pigment is dissolved, and the other is a solvent that lowers the solubility of the dissolved pigment, and at least one of the two types of liquid contains a dispersant,
The flow rate of the liquid to be discharged is set to a flow rate in which L / S is within a range of 26 to 360, where S (mm ² ) is a nozzle opening area and L (ml / min) is a liquid discharge flow rate. The pigment is precipitated and dispersed in the solvent by contact .

In the present invention, the discharge flow rate of the liquid to be discharged is determined to be a flow rate within which L / S is in the range of 26 to 360, where S (mm ² ) is the nozzle opening area and L (ml / min) is the liquid discharge flow rate. Can do.

  The reaction in the present invention includes a reprecipitation reaction. In this case, one of the two types of liquids can be a solution in which the pigment and the dispersant are dissolved, and the other can be a solvent that lowers the solubility of the dissolved pigment.

  The reaction in the present invention includes a coupling reaction. In this case, one of the two types of liquid can be a solution in which a coupler and a dispersant are dissolved, and the other can contain a diazinium salt.

  The reaction in the present invention includes a hydrolysis polycondensation reaction. In this case, one of the two liquids can be an inorganic alkoxide compound solution and the other can be an aqueous solvent.

  According to the method of the present invention, it is possible to eliminate the secondary reaction caused by liquid scattering by suppressing the liquid scattering, and to produce a dispersion stably for a long time.

  The invention includes dispersions. The dispersion of the present invention contains a reaction product obtained by reacting at least two kinds of liquids, and in the dispersion in which particles made of the reaction products are dispersed in a dispersion medium, the progress of the discharged liquid is progressed. Reaction products generated by discharging the at least two kinds of liquids from nozzles individually provided so that the directions intersect with each other within a range of 120 degrees or less, and the liquids then flow together. It is characterized by including.

  One of the two kinds of liquids in the present invention can be a solution in which a pigment and a dispersant are dissolved, and the other can be a solvent that lowers the solubility of the dissolved pigment.

  The dispersion according to the present invention can be used as a pigment for inkjet recording.

  Hereinafter, the dispersion manufacturing method according to the first aspect of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing the entire liquid mixing apparatus system applicable to the method for producing a dispersion of the present invention.

  In FIG. 1, reference numeral 100 denotes a mixing apparatus including nozzles 121 and 122, and liquids discharged from the nozzles 121 and 122 are mixed by contact and recovered by the mixed liquid recovery means 108.

  In FIG. 1, 131 and 132 are liquid supply means, and the liquid is supplied to the liquid supply means 131 and 132 from a liquid storage tank (not shown). As the liquid supply means 131 and 132, a commercially available syringe pump, plunger pump, diaphragm pump, electromagnetic pump, or the like can be employed.

  Monitor means 141 and 142, control means 151 and 152, and temperature control means 161 and 162 are connected between the mixing apparatus 100 and the liquid supply means 131 and 132 via pipes 171 and 172, respectively.

  The monitor means 141 and 142 are constituted by a flow meter, a pressure gauge and the like, and the control means 151 and 152 are constituted by a valve, a valve and the like. The temperature control means 161 and 162 can be constituted by a heater, a cooler or the like.

  These components are connected to the pipes 171 and 172 made of tubes that are resistant to the liquid to be conveyed. Each component provided between the liquid mixing apparatus 100 and the liquid supply means 131 and 132 is provided as necessary, and all components need not be provided.

  The liquid discharged from the nozzles 121 and 122 can be transported to the mixed liquid recovery means 108 by using the flow of the liquid due to its own weight or by the pressure of the pump.

  Next, the form of the liquid mixing apparatus that can be applied to embody the manufacturing method of the present invention will be described with reference to FIGS. A liquid mixing device is a small chemical device for mixing and reacting liquids.

  A liquid mixing apparatus that can be employed here discharges a plurality of liquids from nozzle openings provided individually, and starts mixing by bringing the liquids into contact with each other in a region on an extended line of the nozzles.

  The plurality of nozzles are provided so that the traveling direction of the liquid discharged from the nozzles intersects at 120 degrees or less (θ). If it exceeds 120 degrees, the possibility of scattering of the liquid to be mixed increases.

  Two or more nozzles can be provided.

  Examples of the case where the number of nozzles is two are shown in FIGS.

  In the liquid mixing apparatus 100 shown in FIG. 2, two liquids 191 and 192 are discharged from openings 111 and 112 provided in the two nozzles 121 and 122, respectively.

  Here, the two nozzles 121 and 122 are arranged so that the traveling direction θ of the liquids 191 and 192 is 120 degrees or less.

  In FIG. 2, 221 is an opening surface provided with an opening of a nozzle, 181 is a mixed liquid, and 108 is a mixed liquid recovery means. The mixed liquid 181 moves together in the direction of the mixed liquid recovery means.

  The example shown in FIG. 3 is different from the example shown in FIG. 2 in that the nozzle 122 is arranged more vertically than that shown in FIG. Even in this case, the mixed liquid 181 moves together.

  Further, the example shown in FIG. 4 is different from the examples of FIGS. 2 and 3 in that the liquid discharge direction is substantially perpendicular to the direction of gravity.

  In a liquid mixing apparatus that uses two nozzles, the nozzle arrangement is not limited to that shown here.

  Any liquid may be used as long as the angle formed by the traveling direction of the liquid is within a range of 120 degrees or less and the mixed liquid flows in an integrated manner in consideration of the viscosity of the liquid, the flow velocity of the liquid, and the like.

  The apparatus shown in FIG. 5 is an example in which the number of nozzles is three. A nozzle 123 is provided in addition to the nozzles 121 and 122, and a liquid 193 is discharged from the nozzle 123.

  As described above, the nozzle is provided so that the liquid 181 that has started mixing in a region on the extended line of the nozzle flows integrally in one direction.

  Thus, it is not necessary to provide a carrier fluid for causing the liquid 181 that has started mixing to flow in one direction. In addition, since the liquid that has been mixed does not scatter in multiple directions and is integrated, it is easy to recover without missing the mixed product.

  When the angle formed by the extended line of the nozzle is larger than 120 degrees, the liquid that has started mixing is likely to scatter in multiple directions, and the liquid moves in one direction by newly providing an enclosure or a carrier fluid. Need to be corrected.

  In the present invention, since the liquid flows as a single body, it is not necessary to surround the mixing unit with a casing.

  In the present invention, it is possible to employ a mixing device that is devised according to the required production volume in consideration of mass production.

  The mixing apparatus shown in FIGS. 6 and 7 increases the amount of liquid to be processed by arranging nozzles in parallel.

  In FIG. 6, the nozzle row 125 and the nozzle row 126 are arranged in correspondence, the liquid 195 is ejected from the nozzle row 125, and the liquid 196 is ejected from the nozzle row 126. In the apparatus shown in FIG. 7, the nozzle member 321 has openings 155 formed in rows on the opening surface 221, and the nozzle members 322 are similarly formed with openings 156 in rows.

  Liquids 195 and 196 are ejected in rows from these row openings 155 and 156.

  The apparatus shown in FIG. 8 is configured such that one of the corresponding nozzles 157 can discharge the flaky liquid 195, and the other nozzle 126 is the same as that shown in FIG. .

  In the apparatus shown in FIG. 9, both the pair of nozzles 157 and 158 are configured to discharge the flaky liquids 195 and 196.

  In the present invention, even if solids such as particles are generated in reaction products generated by the reaction of at least two kinds of liquids, the mixing field is not covered with a chamber or the like and is an open space. There is no clogging or product accumulation.

  In the liquid mixing apparatus employed in the method of the present invention, the nozzle openings are preferably provided on different surfaces.

  Providing openings on different surfaces means that a plurality of openings are not provided on the same continuous plane.

  For example, in FIG. 3, the opening 221 of the nozzle 121 and the opening 222 of the nozzle 122 are not provided on the same continuous plane. In the mixing apparatus of FIG. 3, the liquids 191 and 192 discharged from the nozzle 121 and the nozzle 122 are different kinds of liquids.

  Therefore, if the nozzle openings 221 and 222 are provided on the same continuous plane, different types of liquid may circulate on the opening surface, causing a reaction between the different types of liquids.

  More specifically, when a liquid having high wettability with the opening surfaces 221 and 222 is discharged, if the openings are provided on the same continuous surface, a part of the discharged liquid is wetted between the opening surfaces, and the droplets It is considered that the reaction occurs between the nozzle opening surfaces.

  The reaction product generated between the opening surfaces is mixed in the reaction product recovery means, and is mixed into the liquid discharged from the nozzle, thereby inducing a variation in performance and function of the reaction product. Become.

  For this reason, in the liquid mixing apparatus employed in the present invention, it is preferable that the openings of the nozzles for discharging different liquids are provided not on the same continuous plane but on different planes.

  However, the same kind of reaction liquid may be discharged from an opening provided on the same surface. For example, in the apparatus shown in FIG. 7 described above, the opening row 155 of the nozzle member 321 is provided on a continuous plane 221. In this case, the liquid 195 ejected from the opening row 155 is the same type of liquid, and therefore unnecessary reaction does not occur even if the liquid wraps around the opening surface 221.

  The nozzle opening shape may be any of a round shape, an oval shape, a polygon such as a square, and a rectangle. The opening area of each of the plurality of nozzles may be the same or different.

  The short side of the opening diameter of the nozzle is smaller than 5000 μm, preferably 1000 μm or less, more preferably 500 μm or less, and further preferably 100 μm or less.

  Examples of the material used as the nozzle of the liquid mixing apparatus employed in the present invention include metal, glass, silicon, Teflon (registered trademark), ceramics, and plastic.

  Metals, glass, silicon, Teflon (registered trademark), and ceramics are preferable when heat resistance, pressure resistance, and solvent resistance are required, but metals are preferred.

  Examples of the metal include, but are not limited to, stainless steel, hastelloy (Ni—Fe alloy) nickel, gold, platinum, tantalum and the like.

  In any case, the material is selected from materials that are corrosion resistant to the liquid to be discharged.

  Moreover, in order to obtain the corrosion resistance of a nozzle and desired surface energy, you may use what performed the lining process to the nozzle surface.

  In the method for producing a dispersion according to the present invention, at least two kinds of liquids are discharged from nozzle openings provided individually.

  Then, the discharge flow rates of the two types of liquids are determined so that the traveling directions of the discharged liquids intersect each other within a range of 120 degrees or less and at least two types of liquids flow together.

  As a result, the liquid that has been mixed can be recovered without scattering in multiple directions and without losing the reaction product.

  Here, the phrase “at least two kinds of liquids flow together” means that 99% or more of the total amount of liquids to be mixed flow together.

  The conditions for flowing the mixed liquid as a unit are appropriately selected according to the viscosity, flow rate, and the like of the liquid. In the case of a liquid used for a general reaction, the liquid discharge flow rate may be a predetermined flow rate.

For example, the discharge flow rate can be set to a flow rate in which L / S is in the range of 26 to 360, where the nozzle opening area is S (mm ² ) and the liquid discharge flow rate is L (ml / min).

  In the present invention, since at least two liquids collide with each other at a predetermined speed in the mixing region, the inertial force between the liquids works, and the mixing and reaction can be performed instantaneously and efficiently.

  In the method for producing a dispersion of the present invention, when a reaction in which fine particles are generated by contact mixing of liquids is performed, a large number of particles grow based on a large number of nuclei generated by the reaction instantaneously. Are formed.

  Therefore, it is possible to obtain fine particles of a functional substance having a small primary particle size. In addition, since at least two kinds of liquids are always in contact with each other at the same timing, the reaction proceeds in an orderly manner (ordered), so that the particle size distribution can be kept narrow.

  Further, by containing a dispersant for dispersing fine particles that precipitate in at least one of at least two kinds of liquids in a medium, dispersion can be performed instantaneously after the fine particles are generated.

  According to this, aggregation of the generated fine particles is suppressed, and a dispersion of a reaction product having a small particle size can be obtained. In particular, the method for producing a dispersion of the present invention is effective for a case where the particle size of the dispersed particles and the uniformity of the particle size greatly affect the function of the functional substance.

  The liquid discharged from the opening of the nozzle is preferably discharged as a thin rod-like or flaky liquid, and contact and mixing are preferably started in a thin rod-like or flaky state.

  If the contact is made after the liquid has been discharged in a state where the width of the short side of the liquid has greatly expanded, a liquid portion that scatters before contact is formed, and an unmixed liquid portion is likely to occur.

  In addition, when the contact is made with the width of the short side of the liquid greatly widened, the width of the liquid that has started mixing also increases, so the moving distance required for mixing the individual reaction liquids in the mixed liquid increases and the mixing time Becomes longer.

  The short side of the liquid cross section immediately before the liquid contact is generally 1 to 20 times, preferably 1 to 10 times, more preferably 1 to 5 times, and even more preferably 1 to the short side of the nozzle opening diameter. 2 times.

  At least two kinds of liquids are combined so as to cause a reaction after the start of mixing and form a dispersion in which the reaction product is dispersed.

  In this case, not all the substances contained in the liquid need to react. That is, either one of the substances involved in the reaction may be present in excess, or a substance such as a solvent that does not participate in the reaction may be included.

  The reaction product may be solid or liquid in the dispersion medium. When the reaction product is a liquid, it indicates a state where a dispersant having poor solubility in the dispersion medium is dispersed by being adsorbed or chemically bonded to the liquid molecules of the reaction product.

  Reactions that occur after the start of contact mixing of a plurality of types of liquids include, but are not limited to, reprecipitation reaction, coupling reaction, hydrolysis polycondensation reaction, and the like.

  For example, ion reaction, radical reaction, dehydration reaction, addition polymerization, polycondensation, oxidation reaction, reduction reaction, neutralization reaction, enzyme reaction, and the like, and these reactions may be combined.

  In the present invention, a color material is preferably used as the functional substance. As described above, examples of the color material include pigments, and examples include inorganic achromatic pigments, organic and inorganic chromatic pigments, and colorless or light color pigments, metallic luster pigments, and the like.

  For the present invention, a newly synthesized pigment may be used.

  For example, in the reprecipitation reaction, one liquid is a solution in which a pigment is dissolved, and the other liquid is a combination of a pigment precipitation medium (a poor solvent that lowers the solubility of the pigment).

  At this time, the reaction product is a precipitated pigment, and in order to obtain a dispersion in which the pigment is dispersed, a dispersant is contained in one or both of the two types of liquids.

  In particular, if the reaction product pigment has the desired dispersibility in the precipitation medium, the dispersant need not necessarily be included in one or both of the two liquids.

  The kind of pigment applied to the present invention is not particularly limited, and a known pigment can be used.

  For example, phthalocyanine pigments such as metal-free phthalocyanine, copper phthalocyanine, halogenated copper phthalocyanine, and titanyl phthalocyanine; azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; quinacridone pigments; isoindolinone pigments; Indanthrone pigments; diketopyrrolopyrrole pigments; dioxazine pigments; perylene pigments; perinone pigments; anthraquinone pigments and the like can be mentioned, but usable pigments are not limited thereto.

  As the pigment, commercially available pigments may be used. Examples of commercially available pigments for black, cyan, magenta, and yellow are as follows.

  Black pigments include Raven1060, Raven1080, Raven1170, Raven1200, Raven1250, Raven1255, Raven1500, Raven2000, Raven3500, Raven5250, Raven5750, Raven7000, Raven5000U, Raven5000U, Raven5000U L, MOGUL-L, Regal 400R, Regal 660R, Regal 330R, Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1300, Monarch 1400 (above, manufactured by Cabot Corporation), Color Black FW1, Color Black FW2, Color Black FW200, Color Black 18, Color ex S160, Color Black S170, Special Black 4, Peck 6P, Special Black 4P, Special Black 4P, Special Black 4P, Special Black 4A, Special Black 4A, Special Black No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Corporation) and the like.

  Examples of cyan pigments include C.I. I. Pigment Blue-1, C.I. I. Pigment Blue-2, C.I. I. Pigment Blue-3, C.I. I. Pigment Blue-15, C.I. I. Pigment Blue-15: 2, C.I. I. Pigment Blue-15: 3, C.I. I. Pigment Blue-15: 4, C.I. I. Pigment Blue-16, C.I. I. Pigment Blue-22, C.I. I. Pigment Blue-60 and the like.

  Examples of magenta pigments include C.I. I. Pigment Red-5, C.I. I. Pigment Red-7, C.I. I. Pigment Red-12, C.I. I. PigmentRed-48, C.I. I. Pigment Red-48: 1, C.I. I. PigmentRed-57, C.I. I. Pigment Red-112, C.I. I. Pigment Red-122, C.I. I. Pigment Red-123, C.I. I. Pigment Red-146, C.I. I. Pigment Red-168, C.I. I. Pigment Red-184, C.I. I. Pigment Red-202, C.I. I. Pigment Red-207 and the like.

  Examples of yellow pigments include C.I. I. Pigment Yellow-12, C.I. I. Pigment Yellow-13, C.I. I. Pigment Yellow-14, C.I. I. Pigment Yellow-16, C.I. I. Pigment Yellow-17, C.I. I. Pigment Yellow-74, C.I. I. Pigment Yellow-83, C.I. I. Pigment Yellow-93, C.I. I. Pigment Yellow-95, C.I. I. Pigment Yellow-97, C.I. I. Pigment Yellow-98, C.I. I. Pigment Yellow-114, C.I. I. Pigment Yellow-128, C.I. I. Pigment Yellow-129, C.I. I. Pigment Yellow-151, C.I. I. Pigment Yellow-154 and the like.

  Examples of the solvent for dissolving the pigment used in the present invention include the following.

  Any organic solvent can be used as long as it dissolves the organic pigment in the presence of an alkali, but those having a solubility in water of 5% or more are preferably used, and moreover, they can be freely used in water. What mixes is more preferable.

  When the pigment is solubilized using a solvent having a solubility in water of less than 5%, it is disadvantageous in that the organic pigment is difficult to precipitate when mixed with water and tends to be coarse particles.

  It is also disadvantageous in that it tends to adversely affect the dispersion stability of the resulting pigment dispersion.

  Examples of organic solvents include dimethyl sulfoxide, dimethylimidazolidinone, sulfolane, N-methylpyrrolidone, dimethylformamide, acetonitrile, acetone, dioxane, tetramethylurea, hexamethylphosphoramide, hexamethylphosphorotriamide, pyridine, propio Examples thereof include nitrile, butanone, cyclohexanone, tetrahydrofuran, tetrahydropyran, ethylene glycol diacetate, and γ-butyrolactone.

  Of these, dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylimidazolidinone, sulfolane, acetone or acetonitrile are preferred. These can be used alone or in combination of two or more.

  As the acid, any acid can be used as long as it solubilizes the organic pigment in an organic solvent, and an organic protonic acid or an inorganic protonic acid can be used.

  Examples of organic protonic acids include alkyl sulfonic acids such as methane sulfonic acid, ethane sulfonic acid, propane sulfonic acid, and butane sulfonic acid; trifluoromethane sulfonic acid, pentafluoroethane sulfonic acid, and heptafluoropropane sulfone, which are substituted with halogen. Halogenated alkyl sulfonic acids such as acid, nonafluorobutanesulfonic acid, trimethylsilyl trifluoromethanesulfonate; alkyl carboxylic acids such as formic acid, acetic acid, propionic acid, butanoic acid; trifluoroacetic acid, trichloroacetic acid, which are substituted with halogen, Halogenated alkyl carboxylic acids such as chlorocaproic acid, bromocaproic acid and chloroundecanoic acid; aromatic carboxylic acids such as benzoic acid and tetrafluorobenzoic acid; benzenesulfonic acid, toluenesulfonic acid, xylene Sulfonic acid, naphthalene sulfonic acid, and aromatic sulfonic acids such as chlorobenzene sulfonic acid.

  Examples of inorganic acids include sulfuric acid, nitric acid, phosphoric acid, polyphosphoric acid, hydrochloric acid, perchloric acid, hydrobromic acid, hydroiodic acid, and chlorosulfonic acid.

  Moreover, these acids can be used individually by 1 type or in combination of 2 or more types.

  When mixing an acid or alkali with an organic solvent, a solvent having a high solubility in acids such as water, lower alcohol, and glycerin can be added to the organic solvent in order to completely dissolve the acid or alkali. .

  This facilitates dissolution of the organic pigment even in an organic solvent having low acid or alkali solubility.

  The following is an example of a precipitation medium (a poor solvent that lowers the solubility of the pigment).

  That is, polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol and glycerin, monohydric alcohols such as methanol, ethanol and isopropyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl Polyhydric alcohol ethers such as ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, nitrogen-containing solvents such as N-methyl-2-pyrrolidone, substituted pyrrolidone, triethanolamine, butyl acetate, cellosolve acetate, etc. Esters such as methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone Emissions such as cyclohexane, heptane, octane, can be exemplified hydrocarbons such as isooctane.

  Water can be used in the entire pH range, but preferably the pH is between 1 and 14.

  Moreover, you may use these precipitation media individually by 1 type or in mixture of 2 or more types.

  Furthermore, in order to increase the precipitation reaction rate and the dispersion stability of the resulting pigment dispersion, an acid or alkali may be added to the precipitation medium.

  In the case of the coupling reaction, for example, a combination in which one liquid is a coupler solution and the other liquid is a diazonium salt solution can be mentioned.

  At this time, the reaction product becomes an azo compound, and a dispersant is contained in one or both of the two liquids in order to obtain a dispersion of the azo compound.

  However, if the azo compound of the reaction product has a desired dispersibility in the dispersion medium, it is not always necessary to include a dispersant.

  Examples of the azo compound include azo pigments such as azo, bisazo, insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments.

  A commercially available pigment may be used as the pigment. Examples of commercially available pigments are given below.

  That is, C.I. I. Pigment Yellow 74, 93, 94, 95, 120, 128, 151, 154, 166, 175, 180, 181, C.I. I. Pigment Red 5, 31, 144, 146, 147, 150, 166, 176, 184, 269, Pigment Orange 31, and the like.

  As the diazonium salt, a diazinium salt derived from a compound having an aromatic amine or heterocyclic amine structure can be used.

  As the coupler, an aromatic compound having an aniline, phenol or naphthol structure or a coupler having a compound having an acetoacetoxy group can be used, but the coupler is not limited thereto.

  As an example of the hydrolysis polycondensation reaction, one liquid is an inorganic alkoxide and the other liquid is a solution containing water.

  At this time, the reaction product becomes an inorganic alkoxide hydrolysis polycondensate.

  The hydrolysis of the inorganic alkoxide and the subsequent polycondensation reaction are reactions called a sol-gel method. This is a reaction in which an inorganic alkoxide is hydrolyzed and polycondensed in a solution to make the solution a sol in which fine particles of an inorganic oxide or an inorganic hydroxide are dissolved, and the reaction further proceeds to a gel. In order to obtain a dispersion of an inorganic alkoxide hydrolysis polycondensate, a dispersant is contained in one or both of the reaction solution A and the reaction solution B.

  However, if the inorganic alkoxide hydrolysis polycondensation product of the reaction product C has a desired dispersibility with respect to the dispersion medium, the dispersant is not necessarily included in one or both of the reaction solution A and the reaction solution B. There is no need to let it.

An example of the inorganic alkoxide is a compound represented by the following formula (I).
R ¹ _n M (OR ² ) _mn (I)
In formula (I), M is an atom selected from Si, Al, Ti, Zr, Ca, Fe, V, Sn, Li, and Be, R ² is an alkyl group, R ¹ is an alkyl group, and a functional group. An alkyl group, m is the valence of M, and n is an integer from 1 to m.

  Of the compounds of formula (I), those which are widely used are compounds where n = 0, that is, only an alkoxy group is bonded to M.

When M is Ti, the valence m of Ti is 4, and such an alkoxide is represented by Ti (OR ² ) ₄ .

Examples of such a titanium alkoxide include Ti (OCH ₃ ) ₄ , Ti (OC ₂ H ₅ ) ₄ , Ti (OC ₃ H ₇ ) ₄ , Ti (OCH (CH ₃ ) ₂ ) ₄ , Ti (OC ₄ H _{9). 4} ).

When M is Si, the valence m of Si is 4, and such an alkoxide is represented by Si (R ² ) ₄ .

Examples of such alkoxysilane include Si (OCH ₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , H ₂ NCH ₂ Si (OCH ₃ ) ₃ , H ₂ NCH ₂ SiCH ₃ (OCH ₃ ) ₂ , H ₂ NCH. ₂ CH ₂ Si (OCH ₃ ) ₃ , H ₂ NCH ₂ CH ₂ CH ₂ Si (OCH ₂ CH ₃ ) ₃ , HN (CH ₃ ) CH ₂ Si (OCH ₃ ) ₃ , HN (CH ₃ ) CH ₂ CH _{2 Si (OCH 3) 3, HN} (CH 3) CH 2 CH 2 CH 2 Si (OCH 3) 3, HN (CH 3) CH 2 CH 2 CH 2 Si (OCH 2 CH 3) 3, N (CH 3) _{2 CH 2 Si (OCH 3)} 3, N (CH 3) 2 CH 2 CH 2 Si (OCH 3) 3, N (CH 3) 2 CH 2 CH 2 CH 2 Si (OCH 2 CH 3) 3, ^{_{l - N + (CH 3)}} 3 CH 2 Si (OCH 3) 3, Cl - N + (CH 3) 3 CH 2 CH 2 Si (OCH 3) 3, Cl - N + (CH 3) 3 CH 2 CH _{2 CH 2 Si (OCH 3)} 3, Cl - N + (CH 3) 3 CH 2 CH 2 CH 2 Si (OCH 3) 3, Cl - N + (CH 3) 3 CH 2 CH 2 CH 2 Si (OCH _{2 CH 3) 3, C 6} H 5 NHCH 2 CH 2 CH 2 Si (OCH 3) 3, NH 2 CONHCH 2 CH 2 CH 2 Si (OCH 3) 3, NH 2 CH 2 CH 2 NHCH 2 CH 2 CH 2 such as Si _{(OCH 3)} 3 and the like.

When M is Al, the valence m of Al is 3, and such an alkoxide is represented by Al (OR ² ) ₃ .

Examples of such aluminum alkoxide include Al (OCH ₃ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (OC ₃ H ₇ ) ₃ , Al (OCH (CH ₃ ) ₂ ) ₃ , Al (OC ₄ H _{9 3} ).

Other inorganic alkoxides include, for example, Ca (OC ₂ H ₅ ) ₂ , Fe (OC ₂ H ₅ ) ₃ , V (OCH (CH ₃ ) ₂ ) ₄ , Sn (OC (CH ₃ ) ₃ ) 4, Li (OC ₂ H ₅ ), Be (OC ₃ H ₇ ) _{2 and the} like.

Further, an inorganic halide in which OR ² is halogen instead of alkoxy may be used.

  The method for producing the dispersion of the present invention is not limited to the above-described reaction, and can also be used for a method for producing a dispersion of metal nanoparticles.

  As the dispersant, one that dissolves in at least one of at least two kinds of liquids to be mixed is used.

  The dispersant may be soluble or insoluble in the dispersion medium of the reaction product. As the dispersant, it is possible to use a resin or a surfactant having both hydrophilic and hydrophobic portions. Examples of the resin having both hydrophilic and hydrophobic parts include a copolymer of a hydrophilic monomer and a hydrophobic monomer.

  Examples of the hydrophilic monomer include acrylic acid, methacrylic acid, maleic acid, fumaric acid, or the above carboxylic acid monoesters, vinyl sulfonic acid, styrene sulfonic acid, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, and the like.

  Examples of the hydrophobic monomer include styrene derivatives such as styrene and α-methylstyrene, vinylcyclohexane, vinylnaphthalene derivatives, acrylic acid esters, and methacrylic acid esters.

  Copolymers having various configurations such as random, block, and graft copolymers can be used. Of course, both hydrophilic and hydrophobic monomers are not limited to those shown above.

  As the surfactant, an anionic, nonionic, cationic or amphoteric surfactant can be used.

  Anionic surfactants include fatty acid salts, alkyl sulfate esters, alkyl aryl sulfonates, alkyl diaryl ether disulfonates, dialkyl sulfosuccinates, alkyl phosphates, naphthalene sulfonate formalin condensates, polyoxyethylene Examples thereof include alkyl phosphate ester salts and glycerol borate fatty acid esters.

  Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethyleneoxypropylene block copolymer, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, fluorine-based, silicon-based, etc. Can be mentioned.

  Examples of the cationic activator include alkylamine salts, quaternary ammonium salts, alkylpyridinium salts, alkylimidazolium salts and the like.

  Examples of the amphoteric surfactant include alkylbetaines, alkylamine oxides, phosphadylcholines and the like.

  Similarly, the surfactant is not limited to those described above.

  Next, the dispersion which is the second invention of the present invention will be described in detail.

  If the reaction product obtained by performing the above-mentioned reaction using the pigment and the precipitation solvent (poor solvent that lowers the solubility of the dissolved pigment) described in the section of the dispersion production method is used, the pigment particles are put into the dispersion medium. A dispersed pigment dispersion can be obtained.

  The dispersion of the present invention may use the reaction product obtained by the above reaction as it is.

  Also suitable for the purpose and method of use by adjusting the concentration of the pigment dispersion and / or other components from the liquid containing the reaction product after the reaction using means such as filtration, dialysis, and ultrafiltration. Anyway.

  Furthermore, a plurality of types of pigment dispersion particles may be mixed at a certain ratio to impart characteristics such as color and particle size distribution that are different from those of a single pigment. Moreover, you may add a new additive according to a usage method and a use purpose.

  The additive is not particularly limited. For example, if the printing medium is a fibrous material such as paper or has an ink absorbing layer on the surface, a penetrating agent that controls the speed of ink penetration into the printing medium is added. It is possible.

  When the printing means is a nozzle or a slit, a nonionic surfactant for improving the wettability of the wall surface of the nozzle or the like may be used as an additive.

  In the case of a driving method in which an ink jet printer heats and foams with a heater in a nozzle to protrude the ink, an additive for imparting heat resistance to the ink may be added.

  In addition, wetting agents such as glycols, glycol ethers, amides, pyrrolidones, binders, oxygen absorbers, physical property modifiers, charge regulators, antifungal agents, etc., in order to improve the maintenance of quality as inks. An additive such as a chelating agent may be added.

  What is necessary is just to select and add an optimal thing according to the following usage method, and it is not necessary to add anything.

  The method for using the pigment ink using the dispersion of the present invention is not particularly limited.

  A coating ink is applied which is applied to the surface of a print medium having a certain surface such as paper and colors a part or the entire surface.

  As an application method, for example, there is a method in which pigment ink is sprayed onto a printing medium from a nozzle or a slit. As a means for spraying from a nozzle and applying to a print medium, for example, there is an ink jet printer.

  As another coating method, for example, there is a method of coating by bringing a printing jig, to which pigment ink is adhered, into contact with a printing medium.

  Specifically, in addition to a method in which a pigment ink is once soaked in a coating jig that can hold a solution such as a brush or a fibrous nib, and then the coating jig is brought into contact with a printing medium for coating. The following can be mentioned.

  That is, a method of applying a pigment ink attached to the surface of a ball by inserting a rotating ball in contact with the printing medium by inserting a rotating ball at the tip of the nozzle, and a printing jig such as a relief plate, an intaglio plate, and a copying plate There is a method of transferring pigment ink to a printing medium using

  Alternatively, it may be used as a colorant used in a production method in which a material is cured after being suspended in a fluid transparent material, and the material is cured.

  Further, since the dispersant has good stability, the pigment ink itself may be used as a liquid or fluid colorant.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these Examples.

Example 1
In this example, the liquid mixing apparatus 100 shown in FIG. 10 was used. The nozzle 121 for discharging one liquid is made of Teflon (registered trademark) and has an opening diameter of 300 μmφ. The nozzle 122 for discharging the other liquid is made of glass and has an opening diameter of 470 μmφ. The angle formed by the traveling directions of both liquids was 40 degrees.

The liquid discharged from the nozzle 121 was adjusted as follows.
C. I. 100 parts of dimethyl sulfoxide was suspended in 10 parts of Pigment Red 122 quinacridone pigment.
Subsequently, 40 parts of sodium lauryl sulfate was added as a dispersant, and a 25% aqueous potassium hydroxide solution was added until these were dissolved to prepare a reaction solution. Ion exchange water was used as the liquid discharged from the nozzle 122.

  Two types of liquids were supplied to the respective nozzles 121 and 122 using a syringe pump as the liquid supply means.

  The liquid discharged from the nozzle 121 was supplied from the syringe pump at a flow rate of 7 ml / min, and the liquid discharged from the nozzle 122 was supplied at a flow rate of 10 ml / min.

  The two types of liquid discharged from the nozzle contacted each other on the extension line in the traveling direction, and the reprecipitation reaction and dispersion occurred instantaneously to obtain a quinacridone pigment dispersion.

  The particle size of the dispersion was very uniform and the average particle size was 30 nm.

(Example 2)
In this example, the liquid mixing apparatus shown in FIG. 4 was used.

  The nozzle 122 for discharging one liquid is made of Teflon (registered trademark) and has an opening diameter of 200 μmφ. The nozzle 121 for discharging the other liquid is made of glass and has an opening diameter of 310 μmφ. The angle formed by the traveling directions of the two liquids was 90 degrees.

  The liquid discharged from the nozzle 122 was adjusted as follows. C. I. 50 parts of dimethyl sulfoxide was suspended in 10 parts of Pigment Yellow 128 disazo pigment.

  Subsequently, 40 parts of polyoxyethylene lauryl ether was added as a dispersant, and a 25% aqueous potassium hydroxide solution was added until these were dissolved to prepare a reaction solution.

  The liquid discharged from the nozzle 121 was ion exchange water.

  Two types of liquids were supplied to the nozzles 122 and 121 using a plunger pump as the liquid supply means. The liquid was supplied from the plunger pump at a flow rate of 7 ml / min for the nozzle 122 and at a flow rate of 10 ml / min for the nozzle 121.

  The liquid 191 and the liquid 192 were in contact with each other on the extension line in the traveling direction, and a reprecipitation reaction and dispersion occurred instantaneously to obtain a disazo pigment dispersion. The particle size of the dispersion was very uniform and the average particle size was 25 nm.

(Example 3)
In this example, the same liquid mixing apparatus as in the first example was used.

  A 3,3′-dichlorobenzidenetetraazo aqueous solution was passed through the nozzle 121 and a coupler aqueous solution having a concentration of about 5% was passed through the nozzle 122 to synthesize pigment yellow 83 particles. As in the first example, the particle size was small and large. Uniform particles were obtained.

  The nozzle 121 was made of Teflon (registered trademark) with an opening diameter of 300 μmφ, and the nozzle 122 was made of glass with an opening diameter of 470 μmφ. The angle formed by the traveling direction of the liquid 191 and the liquid 192 was 60 degrees.

  The liquid discharged from the nozzle 121 was a 3,3′-dichlorobenzidenetetraazo aqueous solution, and the liquid discharged from the nozzle 122 was a solution obtained by dissolving polyoxyethylene lauryl ether in a coupler aqueous solution having a concentration of about 5%.

  The two types of liquid come into contact with each other on the extension line in the traveling direction, and the synthesis reaction and dispersion occur instantaneously. I. A dispersion of Pigment Yellow 83 was obtained.

  The particles of the obtained dispersion had a very uniform particle size and an average particle size of 30 nm.

(Example 4)
In this example, a liquid mixing apparatus provided with three nozzles shown in FIG. 5 was used.

  Here, the nozzle 121 is made of glass whose surface is modified to a hydrophobic surface and has an opening diameter of 300 μmφ, and the nozzle 122 is made of glass whose surface is modified to a hydrophobic surface and has an opening diameter of 470 μmφ.

  The nozzle 123 is made of Teflon (registered trademark) and has an opening diameter of 470 μmφ. The angle formed by the traveling direction of the liquid 191 ejected from the nozzle 121 and the liquid 192 ejected from the nozzle 122 was 90 degrees.

  The angle formed between the liquid 191 and the traveling direction of the liquid 193 discharged from the nozzle 123 was 60 degrees, and the angle formed between the liquid 192 and the traveling direction of the liquid was 60 degrees.

  Liquid 191 is a solution in which 7 parts by weight of fat-soluble dye oil yellow (manufactured by Orient Chemical) is dissolved in 25 parts by weight of tetrahydrofuran.

  For the liquid 192, a block copolymer was used as a dispersant.

  Here, 2- (4-methylphenyl) ethyl vinyl ether was used as the A segment, 2- (2-methoxyethyloxy) ethyl vinyl ether was used as the B segment, and ethyl 4- (2-vinyloxy) ethoxybenzoate was used as the C segment.

  The copolymer molar ratio was A / B / C = 90/80/14, and the C block of the triblock copolymer was obtained by deprotection of ethyl benzoate.

  A solution dissolved in 10 parts by weight of this triblock copolymer and 25 parts by weight of tetrahydrofuran was prepared as liquid 192.

  As the liquid 193, a 0.1 mol / l potassium hydroxide aqueous solution was used. Liquids 191, 192, and 193 were supplied to the respective nozzles using a plunger pump as the liquid supply means.

  The liquid 191 was supplied from the plunger pump at a flow rate of 6 ml / min, the liquid 192 at a flow rate of 7 ml / min, and the liquid 193 at a flow rate of 14 ml / min.

  Liquid 191, liquid 192, and liquid 193 are in contact with each other in the direction of extension, and the benzoic acid in the C block is neutralized with potassium hydroxide, and the inclusion of the fat-soluble dye oil yellow in the triblock copolymer is instantaneous. A large number of uniform and small micelles were formed.

  The average particle size was 60 nm.

(Example 5)
In this example, the same mixing apparatus as in the first example was used.

  In the embodiment, the liquid 191 discharged from the nozzle 121 was titanium tetraisopropoxide, and the liquid 192 discharged from the nozzle 122 was mixed with liquid in the same manner as in the first embodiment, except that an aqueous isopropyl alcohol solution having a concentration of about 60% was used. .

  As a result, a titania monodisperse was obtained as a hydrolyzed polycondensate, and the average particle size was 30 nm and the particle size was very uniform.

(Comparative Example 1)
A similar reaction was carried out in the same manner as in Example 1 except that the angle formed between the liquid 191 and the liquid 192 was 180 degrees. As such, the liquids scattered in all directions after contact, making it difficult to recover the dispersion. Furthermore, it was confirmed that the scattered dispersion was mixed into the reaction liquid discharged from the nozzle opening when dropped.

  The obtained dispersion had a large particle size and the uniformity of the particle size was low.

(Comparative Example 2)
A similar reaction was performed in the same manner as in Example 1 except that the angle formed between the liquid 191 and the liquid 192 was 130 degrees. Also in this comparative example, scattering of the liquid was confirmed, and it was difficult to recover the dispersion. Furthermore, it was confirmed that the scattered dispersion was mixed into the reaction liquid discharged from the nozzle opening when dropped.

  The obtained dispersion had a large particle size and the uniformity of the particle size was low.

(Example 6)
C. of uniform particle size obtained in Example 1 with an average particle size of 30 nm. I. An ink was prepared using an aqueous solution containing a dispersion of Pigment Red 122 quinacridone pigment particles.

  Specifically, the aqueous solution containing the dispersion was ultrafiltered to remove water together with excess sodium lauryl sulfate dissolved in the liquid, and the pigment particle concentration was concentrated.

  Next, isopropyl alcohol and ethylene glycol were added thereto to obtain a pigment ink for an ink jet printer.

  The pigment ink was filled in a transparent glass container, sealed, and allowed to stand in a laboratory illuminated with fluorescent light at room temperature for several weeks, but precipitation did not occur.

  Further, the absorption spectrum of the ink was measured using an absorptiometer (UV3100: manufactured by Shimadzu Corporation), but there was almost no difference between before and after standing, and the pigment particles maintained dispersibility and were stable as an ink. I understood.

  This ink was appropriately diluted to prepare five types of inks having different concentrations of quinacridone pigment particles.

  Each was filled into an ink cartridge for an inkjet printer manufactured by Canon Inc., the cartridge was loaded into an inkjet printer (PIXUS950: manufactured by Canon Inc.), and printing was performed on photographic image quality inkjet paper (PR-101: manufactured by Canon Inc.). .

  After the ink is dried, the glossiness of 20 degrees and 60 degrees based on the respective JIS Z8741 is measured with a gloss meter (GMX-203: manufactured by Murakami Color Research Laboratory), and the OD (reflection density) is measured with an OD meter (Gretag Macbeth RD). -19: measured by Sakata Inx).

  The results are shown in FIG. 11 and FIG. It was found that 20 degree gloss has a value of about 150 for any OD of 1 to 2.5, and 60 degree gloss has a value of about 130 to 140 for any of OD of 1 to 2.5.

  Moreover, the surface of what was drawn with an ink having an OD of 2.48 was observed with AFM (NanoScope IIIa: manufactured by Bico Co., Ltd.), and the surface roughness in a square area of 2 μm per piece was calculated. The average of the values calculated by observing the three locations was 5.18 nm.

  Similarly, the surface roughness of the photographic image quality inkjet paper itself was also measured by the same method, and the average value was calculated to be 10.4 nm. By printing the pigment ink prepared in this example, the surface roughness was improved by about 5 nm. It was confirmed.

(Comparative Example 3)
A C.I. I. A dispersion was prepared using Pigment Red 122 quinacridone pigment particles using sodium lauryl sulfate as a dispersant and water as a dispersion medium.

  Further, isopropyl alcohol and ethylene glycol were added to obtain a pigment ink for an ink jet printer having the same concentration as in Example 6.

  The pigment ink was printed on a photographic image quality inkjet paper using an inkjet printer in the same manner as in Example 6, and the glossiness and OD were measured.

  The results are shown in FIGS. It was found that the 20-degree gloss has a value of about 110 when the OD is 1 to 2.5, and the 60-degree gloss has a value of about 93 when the OD is 1.2 and about 120 when the OD is more than that.

  The surface roughness of the ink drawn with an ink having an OD of 2.48 was calculated in the same manner as in Example 6. The result was 14.1 nm, and the surface of the printed photographic image quality inkjet paper as well as the surface of Example 6 was printed. I found out that it was worse.

It is a schematic diagram which shows the whole liquid mixing apparatus system using the liquid mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a schematic diagram which shows a part of mixing apparatus applicable to the manufacturing method of the dispersion of this invention. It is a graph of 20 degree | times glossiness of what pigmented the pigment ink of this invention and the general pulverized pigment ink. It is a graph of 60 degree | times glossiness of what pigmented the pigment ink of this invention and the general pulverized pigment ink.

Explanation of symbols

100 Mixer 121, 122, 123, 125, 126, 321, 322 Nozzle 191, 192 Liquid 111, 112, 155, 156 Opening 221, Opening surface

Claims (4)

Includes the step of generating a reaction product by reacting at least two liquids, the particles consisting of the reaction product to a method for producing a dispersion obtained by dispersing in a dispersion medium,
Preparing a nozzle having an opening diameter of 500 μm or less for discharging the liquid;
Traveling direction was discharged the liquid so as to intersect within the following 120 degrees from one another, and discharge said liquid to then flow together at least two kinds of liquid from the nozzles provided individually is brought into contact with the liquid each other by Rukoto, anda step of generating said reaction product,
One of the two types of liquid is a solution in which the pigment is dissolved, and the other is a solvent that lowers the solubility of the dissolved pigment, and at least one of the two types of liquid contains a dispersant,
The flow rate of the liquid to be discharged is set to a flow rate in which L / S is within a range of 26 to 360, where S (mm ² ) is a nozzle opening area and L (ml / min) is a liquid discharge flow rate. A method for producing a dispersion , wherein the pigment is precipitated and dispersed in the solvent by contact .   The method for producing a dispersion according to claim 1, wherein the traveling directions of the liquids intersect in a range of 40 degrees to 90 degrees. The method for producing a dispersion according to claim 1, wherein the pigment is quinacridone . The method for producing a dispersion according to claim 1, wherein the pigment is a disazo pigment .

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