JP2013140227A - Method for producing pigment dispersion for color filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a pigment dispersion for a color filter having a high contrast ratio and a low viscosity while satisfying storage stability which can finely disperse an organic pigment.SOLUTION: There is provided a method for producing a pigment dispersion for a color filter, the method comprising the steps of: a first step of preliminarily dispersing a mixture liquid containing an organic pigment treated with an acrylic resin, a water-insoluble dispersant and an organic solvent by a media type disperser filled with media particles under the conditions of an instantaneous driving force of 0.5 to 3 kW/kg and a cumulative driving force of 2 to 12 kWh/kg; and a second step of mainly dispersing the resulting preliminarily dispersed product by a media type disperser filled with media particles having a particle diameter smaller than that of the media particles in the first step.

Description

  The present invention relates to a method for producing a pigment dispersion for a color filter.

The liquid crystal display device has been mainly used as a monitor for a personal computer. However, in recent years, not only that, but also the development of a monitor for a television has been rapidly progressed, and a color filter is used for color development.
At present, the color filter colored layer is mainly produced by a pigment dispersion method using a pigment having excellent light resistance and heat resistance as a colorant. Generally, if the pigment can be dispersed as fine and stable particles, the scattering with respect to visible light is reduced.
As a method for dispersing a pigment, a method is known in which particles are pulverized and pulverized using a media mill disperser by a shearing force / friction force by stirring and mixing, an impact force between media, and the like.
However, the finer the pigment is, the easier it is for the dispersed particles to re-agglomerate, resulting in an increase in particle diameter and viscosity, which makes it difficult to stabilize the dispersion state.

Until now, in order to achieve high quality (high brightness, high contrast, etc.) color filters, optimization of pigments and pigment dispersants, and refinement of pigments contained in colored layers have been studied. It has been.
Patent Document 1 discloses that a preliminary dispersion is obtained by dispersing a pigment and a first dispersant in an organic solvent using a media-type disperser, and the adsorption rate to the preliminary dispersion and the pigment is smaller than that of the first dispersant. Disclosed is a method for producing a non-aqueous pigment dispersion in which 2 dispersant is further dispersed with a media-type disperser, and then the dispersant not adsorbed on the pigment is removed. According to this method, a non-aqueous pigment dispersion having a low viscosity and a small pigment particle size can be efficiently produced.
Patent Document 2 discloses a method for producing an aqueous recording liquid for an ink jet printer using a dispersion medium stirring type dispersion device having a rotor and a separator in a cylindrical crushing section as a dispersion device.
In Patent Document 3, for the purpose of improving color reproducibility, display quality, particularly black reproducibility, unsaturated carboxylic acid, mono (meth) acrylate having an aliphatic cyclic group, and other monomers copolymerizable therewith A pigment composition containing an acrylic resin that is a copolymer of the above and a pigment is disclosed.
However, the methods described in these documents have a problem that the pigment cannot be made fine enough to improve the contrast ratio.

JP 2011-57823 A JP 2006-16444 A JP 2008-111019 A

  An object of the present invention is to provide a method for producing a pigment dispersion for a color filter that can finely disperse an organic pigment, has a low viscosity, satisfies storage stability, and has a high contrast ratio.

In the method for producing a pigment dispersion for a color filter, the present inventors preliminarily disperse an organic pigment treated with an acrylic resin under a specific condition using a media-type disperser, and then use media particles having a smaller particle size. When the organic pigment is reduced to small particles step by step by the two-stage dispersion treatment, which is the main dispersion treatment, the preliminary dispersion conditions of the first step unexpectedly greatly affect the contrast ratio of the finally evaluated color filter. I found out.
That is, this invention provides the manufacturing method of the pigment dispersion for color filters which has the following 1st process and 2nd process.
First step: A mixed solution containing an organic pigment treated with an acrylic resin, a water-insoluble dispersant, and an organic solvent has an instantaneous power of 0.5 to 3 kW / kg and an integrated power of 2 to 12 kWh / kg. Step of pre-dispersing with a media-type disperser filled with media particles under the conditions Second step: Media particles having a particle size smaller than the particle size of the media particles in the first step of the pre-dispersion obtained in the first step In addition, although the said patent document 1 is the same as this invention in the point which carries out the two-stage dispersion processing of the pigment, the pigment to be used is not the pigment previously processed with resin. Therefore, the cohesive strength of the pigment is strong, and higher instantaneous power is required in the first step than in the method of the present invention.

  According to the present invention, an organic pigment can be finely dispersed, and a pigment dispersion for a color filter having a high contrast ratio can be efficiently produced while satisfying storage stability with low viscosity.

It is sectional drawing which shows an example of the media-type disperser used by this invention.

The manufacturing method of the pigment dispersion for color filters of this invention has the following 1st process and 2nd process, It is characterized by the above-mentioned.
First step: A mixed solution containing an organic pigment treated with an acrylic resin, a water-insoluble dispersant, and an organic solvent has an instantaneous power of 0.5 to 3 kW / kg and an integrated power of 2 to 12 kWh / kg. A step of pre-dispersing with a media-type disperser filled with media particles under the conditions;
Second step: A step of subjecting the preliminary dispersion obtained in the first step to a main dispersion treatment using a media-type disperser filled with media particles having a particle size smaller than that of the media particles in the first step. Each component to be used and each process will be described.

[Organic pigments treated with acrylic resin]
The organic pigment treated with the acrylic resin used in the present invention may be a pigment in which the organic pigment and the acrylic resin are physically or chemically bonded. It is considered that the organic pigment treated with the acrylic resin is capable of suppressing reaggregation of the pigments at the time of pulverizing the pigment and making the pigment relatively small in particle size. This is thought to suppress the generation of coarse particles and increase the contrast ratio. The physical bond means adsorption of a resin to an organic pigment, coating with an organic pigment, or the like.

<Organic pigment>
The organic pigment used in the present invention (hereinafter also simply referred to as “pigment”) is not particularly limited as long as it is suitably used for a color filter, such as an azo pigment, a phthalocyanine pigment, a condensed polycyclic pigment, and a lake pigment. Is mentioned.
As the azo pigment, C.I. I. Insoluble azo pigments such as CI Pigment Red 3; I. Soluble red azo pigments such as CI Pigment Red 48: 1; I. And condensed azo pigments such as CI Pigment Red 144. Examples of the phthalocyanine pigment include C.I. I. And copper phthalocyanine pigments such as CI Pigment Blue 15: 6.
Examples of the condensed polycyclic pigment include C.I. I. Anthraquinone pigments such as CI Pigment Red 177; I. Perylene pigments such as CI Pigment Red 123; I. Perinone pigments such as C.I. Pigment Orange 43; I. Quinacridone pigments such as C.I. Pigment Red 122; I. Dioxazine pigments such as CI Pigment Violet 23, C.I. I. Pigment Yellow 109 and other isoindolinone pigments, C.I. I. Pigment Orange 66 and other isoindoline pigments, C.I. I. Quinophthalone pigments such as CI Pigment Yellow 138; I. Pigment azo complex pigments such as CI Pigment Yellow 150, C.I. I. Indigo pigments such as CI Pigment Red 88; I. Metal complex pigments such as C.I. Pigment Green 8; I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. And diketopyrrolopyrrole pigments such as CI Pigment Orange 71.
Among these, a diketopyrrolopyrrole pigment represented by the following general formula (1) is preferable from the viewpoint of more effectively expressing the effects of the present invention.

In formula (1), X ¹ and X ² each independently represent a hydrogen atom or a halogen atom such as a fluorine atom or a chlorine atom, and Y ¹ and Y ² each independently represent a hydrogen atom or —SO 2. Indicates a ₃ H group.
Suitable examples of commercially available diketopyrrolopyrrole pigments include BASF Corporation C.I. I. Pigment Red 254, trade names "Irgaphor Red BK-CF", "Irgaphor Red BT-CF", "Irgazin DPP Red BO", "Irgazin DPP Red BL", "Cromophtal DPP Red BP", "Cromophtal DPP Red BOC", etc. Is mentioned.
There is no restriction | limiting in particular in the manufacturing method of the diketopyrrolopyrrole pigment represented by General formula (1). For example, it is produced by reacting benzonitrile or halogenated benzonitrile with a halogenated acetate such as bromoacetate in the presence of a reducing agent such as zinc powder, or by further sulfonating the obtained compound. be able to.
The above pigments can be used alone or in combination of two or more.

<Acrylic resin>
The acrylic resin is produced by polymerizing a monomer mixture containing (A) (meth) acrylic acid monomer and (B) hydrophobic monomer.
(A) The (meth) acrylic acid monomer is used from the viewpoint of improving dispersion stability by adsorbability with the pigment. (Meth) acrylic acid means acrylic acid and / or methacrylic acid.

(B) The hydrophobic acrylic monomer is one or more selected from alkyl (meth) acrylates and aromatic group-containing monomers from the viewpoint of increasing the dispersibility in an organic solvent and reducing the viscosity of the pigment dispersion. Is preferably contained.
Examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, (iso) propyl (meth) acrylate, (iso or tertiary) butyl (meth) acrylate, (iso) amyl (meth) acrylate, Cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (iso) octyl (meth) acrylate, (iso) decyl (meth) acrylate, (iso) dodecyl (meth) acrylate, (iso) stearyl (meth) acrylate, Examples thereof include (meth) acrylic acid esters having a hydrocarbon group having 1 to 22 carbon atoms, preferably 6 to 22 carbon atoms, such as isobornyl (meth) acrylate adamantyl (meth) acrylate.
In addition, said (iso or tertiary) and (iso) mean both the case where these groups exist, and the case where it is not so, and when these groups do not exist, normal is shown.

  Aromatic group-containing monomers are styrene, vinyl naphthalene, α-methyl styrene, vinyl toluene, ethyl vinyl benzene, 4-vinyl biphenyl, 1,1-diphenyl ethylene, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, 2 One or more selected from -hydroxy-3-phenoxypropyl acrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2-acryloyloxyethyl phthalate and neopentyl glycol acrylate benzoate are preferred. Among these, aromatic group-containing (meth) acrylates such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate are preferable from the viewpoint of increasing dispersibility in an organic solvent and reducing the viscosity of the pigment dispersion. More preferred is benzyl (meth) acrylate.

In addition, other monomers can be used in combination as long as the object of the present invention is not impaired.
As the other monomer, (C) a nonionic monomer is preferable.
(C) The nonionic monomer is used from the viewpoint of improving the affinity between the pigment and the resin and improving the dispersion stability of the pigment. (C) As a nonionic monomer, what is represented by following General formula (2) is preferable.
CH ₂ = CR ¹ COO (AO) _p R ² (2)
In Formula (2), R ¹ represents a hydrogen atom or a methyl group, and R ² represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group optionally substituted with an alkyl group having 1 to 9 carbon atoms. Show. AO represents an oxyalkylene unit having 2 to 4 carbon atoms, p represents an average added mole number, and is a number of 1 to 25. The p oxyalkylene units may be the same or different.
The oxyalkylene unit is preferably an oxyethylene unit, an oxypropylene unit, or an oxytetramethylene unit. When the oxyalkylene units are different, any of block addition, random addition, and alternate addition may be used.
(C) Nonionic monomers include methoxypolyethylene glycol mono (meth) acrylate, polyethylene glycol mono (meth) acrylate, methoxypolypropylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and the like.
Said various monomers can be used individually or in mixture of 2 or more types.

The content of the (A) (meth) acrylic acid monomer in the monomer mixture is preferably 3 to 40% by weight, more preferably 5 to 30% by weight, and still more preferably, from the viewpoint of improving dispersion stability due to adsorptivity with the pigment. Is 7 to 25% by weight.
The content of the (B) hydrophobic monomer in the monomer mixture is preferably 15 to 87% by weight, more preferably 35 to 85% by weight, and still more preferably 60 to 83% by weight from the viewpoint of lowering the viscosity.
When the (C) nonionic monomer is further used, the content of the (C) nonionic monomer in the monomer mixture is preferably from 5 to 45% by weight, more preferably from 5 to 35%, from the viewpoint of dispersion stability of the pigment. % By weight, more preferably 5 to 30% by weight.

<Treatment of organic pigments with acrylic resin>
As a method of treating an organic pigment with an acrylic resin, after the pigment and the acrylic resin are present in an aqueous solvent, (i) the aqueous solvent is acidified, or (ii) the aqueous solvent is removed. And a method of physically or chemically adsorbing or binding an acrylic resin to the pigment surface.
Here, “aqueous” of the aqueous solvent means that water accounts for the largest proportion in the solvent, and may be 100% by weight of water. Also included are mixtures with organic solvents. In the aqueous solvent, the pigment content is preferably 0.5 to 30% by weight, more preferably 1 to 20% by weight, and the acrylic resin content is preferably 0.01 to 30% by weight, and 0.1 to 10%. % By weight is more preferable, and the content of the aqueous solvent (preferably water) is preferably 60 to 99% by weight, and more preferably 70 to 98% by weight.
For removal of the aqueous solvent, a known method such as reduced pressure, heating, or filtration can be used. The aqueous solvent may be removed almost completely or may remain. In the pigment treated with the water-insoluble polymer particles after removing the aqueous solvent, the residual content of the aqueous solvent is preferably 5% by weight or less, and more preferably 0.1% by weight or less. If necessary, pulverization may be performed after removing the aqueous solvent.
When making the aqueous solvent acidic, it is preferable to adjust the pH to 3 to 5 with hydrochloric acid, phosphoric acid or the like. Then, if necessary, it can be filtered, washed with water and pulverized.
The weight ratio of the pigment to the acrylic resin (acrylic resin / pigment) is preferably 0.05 to 0.25, and preferably 0.08 to 0 from the viewpoint of improving the dispersibility of the pigment and obtaining a color filter having a high contrast ratio. .17 is more preferred.

[Water-insoluble dispersant]
The water-insoluble dispersant used in the present invention is prepared by dispersing the organic pigment in a state of being stably fined in an organic solvent, reducing coarse particles, and increasing the contrast ratio. It is preferable that the water-insoluble dispersant used in Step 1 and Step 2 is essentially the same. As such a water-insoluble dispersant, a basic urethane resin is preferably used in both Step 1 and Step 2.
The amine value of the water-insoluble dispersant is preferably 3 to 20 mg KOH / g, more preferably 5 to 17 mg KOH / g, still more preferably 5 to 15 mg KOH / g, and still more preferably from the viewpoint of increasing the adsorption rate to the pigment. 5-9 mg KOH / g. When two or more water-insoluble dispersants are used, the weight is determined as a weighted average of individual amine values of the water-insoluble dispersant.
In order for the water-insoluble dispersant used in Step 1 and Step 2 to be essentially the same, the difference in the amine value of the basic urethane resin used in Step 1 and Step 2 increases the adsorptivity to the pigment. Therefore, it is preferably 10 mgKOH / g or less, more preferably 5 mgKOH / g or less, and still more preferably 3 mgKOH / g or less.

As the basic urethane resin dispersant, a compound having a number average molecular weight of 300 to 10,000 having at least one hydroxyl group in the molecule and a functional group capable of reacting with the isocyanate group in the molecule are added to the isocyanate group of the polyisocyanate compound. What was obtained by making the basic group containing compound which has it react is preferable.
Here, the polyisocyanate compound is preferably a polyisocyanate having an isocyanuric group based on a diisocyanate such as tolylene diisocyanate or isophorone diisohyahynate.
Examples of the compound having one or more hydroxyl groups in the molecule include polyether compounds and polyester compounds, such as polyethylene glycol.
As the basic group-containing compound having a functional group capable of reacting with an isocyanate group in the molecule, one or more compounds selected from polyols having N, N-disubstituted amino groups or heterocyclic nitrogen atoms, polythiols, and amines For example, N, N-dimethyl-1,3-propanediamine and the like.
Here, the “water-insoluble dispersant” means that when the dispersant is dried at 105 ° C. for 2 hours and then dissolved in 100 g of water at 25 ° C., the dissolution amount is 10 g or less, preferably 5 g or less, The dispersant is preferably 1 g or less. When the dispersant has a salt-forming group, the dissolution amount is a dissolution amount when the salt-forming group of the dispersant is 100% neutralized with acetic acid or sodium hydroxide depending on the type.

Examples of the water-insoluble dispersant include an amide skeleton in the main chain described in JP-A-3-277673, JP-A-10-339949, JP-T-2003-517063, etc., and the side chain is methacrylic. Graft polymer comprising macromonomer by acid ester; polyester oligomer having aliphatic hydroxycarboxylic acid residue described in JP-B-7-96654, JP-A-7-207178, etc .; organosiloxane polymer (Shin-Etsu Chemical Co., Ltd.) Company, KP341, KP575, etc.); (Meth) acrylic acid-based (co) polymer (Kyoei Yushi Chemical Co., Ltd., Polyflow No. 75, 90, 95, etc.); 3000, 5000, 9000, 12000, 13240, 13940, 17 Various Solsperse dispersants such as 00, 20000, 24000, 26000, and 28000, Ajisper PB-821, 822, 880, and 881 manufactured by Ajinomoto Fine Techno Co., Ltd., and Isonet S-20 manufactured by Sanyo Chemical Co., Ltd. And various Disperbyk dispersants such as Disperbyk-161, 162, 2163, 2164 manufactured by Big Chemie Japan Co., Ltd., and the like.
Said dispersing agent can be used individually or in combination of 2 or more types.

[Organic solvent]
The organic solvent is not particularly limited as long as it is a liquid organic solvent under the conditions for the dispersion treatment.
Preferred examples of the organic solvent include, for example, a lower alcohol having 1 to 4 carbon atoms such as ethanol and isopropyl alcohol; a ketone such as acetone and methyl ethyl ketone; toluene and xylene from the viewpoint of dispersibility between the organic pigment and the water-insoluble dispersant. Aromatic hydrocarbons such as cyclohexane, aliphatic hydrocarbons such as cyclohexane, polyhydric alcohols such as propylene glycol, ethers such as ethylene glycol diethyl ether, ethyl acetate, silicone oil, higher alcohols, oils and fats, and the following general formula ( Examples thereof include compounds represented by 3).

(In the formula, R ³ and R ⁴ each independently represent a linear or branched alkyl group having 1 to 4 carbon atoms, and R ⁵ represents a hydrogen atom or a methyl group.)
In the general formula (3), the alkyl group having 1 to ⁴ carbon atoms of R ³ and R ⁴ includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a sec-butyl group. , And tert-butyl group. In these, a methyl group and an ethyl group are preferable.
For color filter applications, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA) from the viewpoint of dispersibility of pigments such as diketopyrrolopyrrole pigments and solubility or dispersibility of polymer dispersants , One or more selected from the group consisting of diethylene glycol monobutyl ether acetate (BCA) and propylene glycol monoethyl ether acetate are particularly preferred.
Said organic solvent can be used individually or in combination of 2 or more types.

The amount of the pigment in the dispersion is preferably 1% by weight or more, more preferably 5% by weight or more, and still more preferably 10% by weight or more from the viewpoint of improving productivity during dispersion. Further, from the viewpoint of ensuring handling properties during dispersion, it is preferably 60% by weight or less, more preferably 50% by weight or less, and still more preferably 40% by weight or less.
The amount of the water-insoluble dispersant in the dispersion is preferably an addition amount that does not become insufficient in the dispersion treatment process from the viewpoint of improving the dispersion stability. Specifically, it is 10% by weight or more, preferably 20% by weight or more, more preferably 30% by weight or more based on the pigment weight. Further, from the viewpoint of obtaining a dispersion having an appropriate viscosity, the content is 200% by weight or less, preferably 150% by weight or less, more preferably 100% by weight or less based on the pigment weight.
The amount of the organic solvent in the dispersion is the amount excluding the pigment concentration, the water-insoluble dispersant, and other additives, but from the viewpoint of operability during the dispersion treatment in each manufacturing process and making the pigment finer, It selects suitably in each manufacturing process.

[Manufacture of pigment dispersions for color filters]
In the manufacturing method of the pigment dispersion for color filters of this invention, the following 1st process and 2nd process are performed.
First step: A mixed solution containing an organic pigment treated with an acrylic resin, a water-insoluble dispersant, and an organic solvent has an instantaneous power of 0.5 to 3 kW / kg and an integrated power of 2 to 12 kWh / kg. A step of pre-dispersing with a media-type disperser filled with media particles under the conditions;
Second step: A step of subjecting the preliminary dispersion obtained in the first step to a main dispersion treatment using a media-type disperser filled with media particles having a particle size smaller than that of the media particles in the first step.

[First step]
In the first step, a mixed liquid (hereinafter also referred to simply as “mixed liquid”) containing an organic pigment treated with an acrylic resin, a water-insoluble dispersant, and an organic solvent is preliminarily prepared by a media type dispersing machine filled with media particles. This is a process of distributed processing.
By this preliminary dispersion treatment step, the pigment giant particles can be pulverized to effectively reduce the amount of coarse particles. At this time, it is important that the operation conditions in the preliminary dispersion treatment process be performed under low energy conditions in which the instantaneous power of the disperser is 0.5 to 3 kW / kg and the integrated power is 2 to 12 kWh / kg. This is because relatively large media particles are used in order to efficiently pulverize the giant pigment particles, and when compared with the same media particle filling rate, the collision energy between the media particles increases with the larger media particles.
Therefore, if the instantaneous power or accumulated power during dispersion exceeds the above range, the crystal structure of the primary particles of the pigment is crushed by excessive force, the hue changes, the acrylic resin is detached from the pigment, and aggregation occurs. As a result, it becomes difficult to reduce the particle size of the pigment and to reduce the coarse particles.

The average particle diameter of the organic pigment after completion of the first step (the particle diameter at which the cumulative volume frequency calculated by the volume fraction becomes 50% by accumulation from the small particle diameter side: D50) is preferably 0.5 μm or less. It is preferably adjusted to 0.3 μm or less, more preferably 0.15 μm or less.
Further, from the viewpoint of reducing the content of coarse pigment particles, D90 after completion of the first step (particle size in which the cumulative volume frequency calculated by the volume fraction is 90% cumulative from the small particle size side) is preferable. Is adjusted to 1 μm or less, more preferably 0.6 μm or less, and still more preferably 0.4 μm or less. In addition, average particle diameter (D50) and D90 can be measured by the method of an Example.
Although there is no particular limitation on the mixing order of each component, it is possible to add a pigment to an organic solvent from the viewpoint of enhancing productivity in consideration of the bulk specific gravity of the pigment and the ease of mixing the pigment and the organic solvent. preferable. The water-insoluble dispersant is preferably added before and after the pigment is added.

In the pre-dispersion process of the first step, it is said that the raw material such as the organic pigment, the water-insoluble dispersant, and the organic solvent treated with the acrylic resin is mixed in advance, and then the media type disperser is processed more efficiently. Desirable from a viewpoint.
As the mixing device, a commonly used mixing and stirring device such as an anchor blade can be used. Among the mixing and stirring devices, Ultra Disper (Iwata Iron Works Co., Ltd., trade name), Ebara Milder (Ebara Manufacturing Co., Ltd., trade name), TK homomixer, TK pipeline mixer, TK homojetter, TK homomic line flow, Philmix (above, Primix Co., Ltd., trade name), Ultra Turrax, DISPAX-REACTOR, Colloid Mill, CMS, MHD (IKA Japan Co., Ltd., trade name), Clear Mix (M Technique Co., Ltd., trade name), A high-speed stirring and mixing apparatus such as KD Mill (Kinetic Dispersion, trade name) is preferred.

Next, the obtained mixed liquid is pre-dispersed by a media type disperser filled with media particles having a high atomization effect on coarse pigment particles. Media mills used for pre-dispersion include SC mill (Nihon Coke Kogyo Co., Ltd., trade name), Star Mill LMZ (Ashizawa Finetech Co., trade name), Dino Mill (Shinmaru Enterprises Co., Ltd., trade name) , DCP Super Flow, Cosmo, Advantis (Buhler Co., Ltd., trade name), Paint Shaker, Nano Glen Mill (Iwata Iron Works Co., Ltd., trade name), and the like.
The filling rate of the media particles in the dispersion chamber of the media type dispersing machine is preferably in the range of 30 to 90% by volume, more preferably 60 to 90% by volume, and 65 to 80% by volume based on the space in the dispersion chamber. % Is more preferable. In this range, effects such as crushing, shearing, and collision with media particles are exhibited. The “filling rate” of the media particles is represented by the ratio of the apparent volume of the filled beads to the volume of the internal space portion of the disperser container. Here, the “apparent volume of the beads” is a value obtained by dividing the mass of the beads by the bulk density occupied by the beads, and the bulk density can be obtained from the mass of the beads filled in a 1 L container.
5-15 m / s is preferable, as for the rotational speed of the rotating shaft of a media type disperser, 7-13 m / s is more preferable, and 8-12 m / s is still more preferable. The rotational speed is the peripheral speed of the most advanced part of the rotor.

Examples of the material of the media particles include high-hardness metals such as steel and chromium alloy, high-hardness ceramics such as alumina, zirconia, zircon, and titania, and polymer materials such as glass, ultrahigh molecular weight polyethylene, and nylon. Since the magnitude of the shearing force, collision force, and pulverizing force for atomizing the pigment increases as the specific gravity of the media particles increases, among them, ceramic media particles having a relatively large specific gravity are preferable. From the viewpoint of wear resistance, zirconia, titania and the like are more preferable.
The size of the media particles is preferably 0.1 mm or more, more preferably 0.2 mm or more, from the viewpoint of efficiently reducing the coarse particles of the pigment and making the pigment finer. Moreover, from a viewpoint of reducing the damage given to a pigment as much as possible, 1 mm or less is preferable, 0.5 mm or less is more preferable, 0.1-1 mm is still more preferable, 0.2-0.5 mm is still more preferable.

The conditions for the pre-dispersion of the pigment are such that the instantaneous power is 0.5 to 3 kW / kg per kg of the pre-dispersion so that the energy required for the dispersion is not too small, or conversely, excessive energy is not given to the pigment. 0.8-2 kW / kg is preferable, 0.8-1.6 kW / kg is more preferable, and 0.9-1.3 kW / kg is still more preferable. The integrated power is dispersed as 2 to 12 kWh / kg, preferably 2.5 to 10 kWh / kg, more preferably 5 to 9 kWh / kg.
Here, “instantaneous power” and “integrated power” mean a net instantaneous power amount applied to 1 kg of the mixed liquid by a disperser for pre-dispersion and a value obtained by multiplying the instantaneous power amount by time, respectively. . The net power means the power obtained by subtracting the idling power from the actual load power to the disperser, and the idling power means the power in the absence of the media particles and the dispersion medium.
In practice, both “instantaneous power” and “integrated power” can be obtained using an integrated wattmeter or ammeter and voltmeter.
Further, the temperature at the time of preliminary dispersion of the pigment is preferably 0 to 40 ° C, more preferably 5 to 30 ° C from the viewpoint of suppressing deterioration of the dispersion stability of the pigment.

As the media type disperser used for the preliminary dispersion treatment in the first step, a media agitation type wet disperser is preferable, and an SC mill manufactured by Nippon Coke Industries Co., Ltd. is particularly preferable from the viewpoint of preliminary dispersion efficiency and processing flow rate.
FIG. 1 is a cross-sectional view of an SC mill as an example of a media type dispersing machine, wherein 1 is an external fixed container, 2 is a separator, 3 is a cylindrical rotor, 4 is a liquid chamber, 5 is an outer chamber, 6 is a slit, 7 is media particles, 8 is a supply port, 9 is a discharge port, 10 is a rotating shaft of the rotor, and 11 is a liquid discharge hole.
The SC mill shown in FIG. 1 has a cylindrical external fixed container (1) closed at both ends, a separator (2) and a rotor (3) provided with the same axis in the inside, and a separator (2 ) Divides the inside of the container (1) into two in the radial direction of the shaft to form the liquid chamber (4) and the outer chamber (5), and communicates between the liquid chamber (4) and the outer chamber (5). A plurality of slits (6) are provided on at least a part of the peripheral surface of the separator (2), and the rotor (3) is provided in the liquid chamber (4) so as to be rotatable about the rotation shaft (10). The liquid chamber (4) is filled with media particles (7) of a predetermined diameter for pulverizing the pigment in the mixed liquid, and the supply port for supplying the mixed liquid to the liquid chamber (4) (8) and a discharge port (9) for discharging the mixed liquid (preliminary dispersion) that has been subjected to the dispersion treatment from the outer chamber (5).
In FIG. 1, the ratio (L / D) of the length (L) in the rotation axis direction in the external fixed container (1) and the inner diameter (D) of the external fixed container (1) is the residence time and dispersion efficiency of the mixed liquid. In view of the above, 1 or less is preferable, 0.5 or less is more preferable, and 0.4 or less is more preferable.

The direction of the rotation axis (10) of the SC mill is arbitrary, but it is preferably horizontal in order to effectively use the centrifugal force.
A hollow chamber (A) is provided inside the cylinder of the rotor (3), and a plurality of liquid discharge holes (11) consisting of holes or cuts are provided on the cylindrical side wall of the rotor (3). The liquid mixture supplied from the supply port (8) passes through the hollow chamber (A), passes through the liquid discharge hole (11) as shown by the arrow, and is supplied to the liquid chamber (4). The liquid chamber (4) is formed by a gap between the cylindrical side wall of the rotor (3) and the separator (2) facing it.
The liquid discharge hole (11) has a hole diameter larger than the outer diameter of the media particles (7), and the mixed liquid is supplied from the liquid discharge hole (11) to the liquid chamber (4), but the separator (2 ) Is smaller than the outer diameter of the media particles (7), the media particles (7) do not flow out into the outer chamber (5).

The media-type disperser represented by the SC mill rotates from the supply port (8) of the external fixed container (1) toward the rotor (3) while rotating the rotor (3) attached to the rotating shaft (10). The mixed liquid is supplied, and the mixed liquid that has passed through the separator (2) through the media particles (7) in the liquid chamber (4) is discharged as a dispersion from the discharge port (9) of the container (1) by centrifugal force. At this time, however, the pigment is pulverized according to the principle specific to the disperser.
That is, when the rotor (3) is rotated, centrifugal force is generated, and the liquid mixture is supplied into the liquid chamber (4) through the liquid discharge hole (11). The media particles (7) in the liquid chamber (4) are pressed against the inner wall of the separator (2) or moved violently to generate a strong shearing force between the media particles (7). Is pulverized and dispersed in the liquid chamber (4). Among the pigments in the mixed solution, pigment particles larger than the hole diameter of the slit (6) provided in the separator (2) are smaller than the hole diameter of the slit (6) provided in the separator (2). At this stage, it passes through the hole and is discharged from the discharge port (9) together with the liquid medium of the mixed liquid (preliminary dispersion).
Furthermore, since the centrifugal force and the flow direction of the mixed liquid containing the pigment are the same, uniform pulverization / dispersion and a large amount of the dispersed mixed liquid (preliminary dispersion) can be discharged from the separator (2). In addition, the average residence time per pass of the mixed liquid in the disperser can be made relatively short. As a result, it is possible to prevent an increase in the particle size and viscosity of the pigment dispersion due to heat generation. Furthermore, since the number of passes through the disperser is relatively large, the coarse particles of the pigment can be rapidly reduced, and a preliminary dispersion having a relatively sharp particle size distribution can be obtained.
The residence time of the mixed liquid in the disperser is preferably 60 seconds or less / pass (pass), and more preferably 30 seconds or less / pass (pass). Here, the “average residence time” means a value obtained by dividing the space volume obtained by removing the volume of media particles from the volume in the disperser by the processing flow rate.

[Second step]
The second step is a step of subjecting the preliminary dispersion obtained in the first step to a main dispersion treatment using a media type dispersing machine filled with media particles having a particle size smaller than that of the media particles in the first step.
By performing this step, the pigment obtained in the first step can be further refined, and a pigment dispersion for a color filter having a uniform particle size and a high contrast ratio can be obtained. In this process, since relatively small media particles are used, excessive energy is hardly applied, and the crystal structure of the pigment is difficult to be destroyed in a normal use range.

The media particle diameter to be used is made smaller than the media particle diameter used in the first step from the viewpoint of increasing the efficiency of the dispersion process. That is, the media particle diameter used in the second step is preferably 0.08 mm or less, and more preferably 0.06 mm or less. On the other hand, when the media particle diameter is too small, dispersion is difficult to proceed, so 0.003 mm or more is preferable, 0.005 mm or more is more preferable, 0.01 mm or more is further preferable, and 0.003 to 0.08 mm is preferable. 0.005-0.06 mm is more preferable, and 0.01-0.06 mm is still more preferable.
The material of the medium to be used is not particularly limited, but a ceramic medium such as alumina, zirconia, silicon carbide, or silicon nitride is preferable from the viewpoint of reducing metal impurities in the dispersion as in the first step. .
The condition for dispersing the pigment in the second step is that the instantaneous power is preferably 0.5 to 6 kW / kg, and preferably 1 to 3 kW / kg per 1 kg of the pigment dispersion obtained in the first step. More preferred. Moreover, 5-20 kWh / kg is preferable and integrated power is more preferable 7-15 kWh / kg.
Further, the temperature during the pigment dispersion treatment in the second step is preferably 0 to 40 ° C., more preferably 5 to 30 ° C., from the viewpoint of suppressing deterioration of the dispersion stability of the pigment.
The preferable range of the filling rate of the media particles in the dispersion chamber of the media type dispersing machine and the rotation speed of the rotating shaft is the same as in the first step.

The media-type disperser used for the main dispersion treatment in the second step is a disperser that continuously disperses the preliminary dispersion obtained in the first step and continuously separates the obtained dispersion from the media. Is preferred. Such a media-type disperser has, for example, a structure in which a plurality of agitator disks (rotors) mounted on a drive shaft are arranged in a cylindrical dispersion chamber having a liquid supply port, and a large number of media particles are built in the internal space. Have. When the dispersion (slurry) is continuously introduced into the dispersion chamber from the liquid supply port while the agitator disk is rotated by the rotation of the drive shaft, a strong shearing force is applied to the media particles and the dispersion, and the pigment in the dispersion. Is pulverized and finely dispersed. The dispersion in which the pigment is finely dispersed is separated from the media particles and conveyed to the outside from a liquid discharge port provided in the upper part of the dispersion chamber. As a method for separating the dispersion from the media particles, a centrifugal separation method or a combination of a screen and a centrifugal separation can be employed.
Media-type dispersers used in the second step include Star Mill Nano Getter, Star Mill ZRS (Ashizawa Finetech Co., Ltd., trade name), Ultra Apex Mill, Dual Apex Mill (Shou Kogyo Co., Ltd., trade name), Paint Shaker, Pico Glen Mill (Iwata Iron Works Co., Ltd., trade name), Micromedia (Buhler Co., Ltd., trade name), MSC Mill (Nippon Coke Industries Co., Ltd., trade name), sand mill, etc. are listed. An ultra apex mill is more preferable.

According to the first step and the second step, a pigment dispersion for a color filter having few coarse particles, low viscosity and excellent storage stability can be produced. From the viewpoint of miniaturization, a process using a high-pressure homogenizer, an ultrasonic homogenizer, or the like can be appropriately combined after the second process. In addition, from the viewpoint of reducing residual particles such as coarse particles and media particles remaining in the dispersion, and from the viewpoint of removing unnecessary dispersant present in the dispersion, a process using centrifugation or filtration, etc. It can also be combined appropriately.
The average particle diameter (D50) of the pigment dispersion in the present invention is preferably 70 nm or less, more preferably 60 nm or less, further preferably 57 nm or less, more preferably 20 to 70 nm, more preferably 30 to 60 nm, further preferably 35 to 57 nm. preferable. The viscosity of the pigment dispersion obtained in the present invention is preferably 1 to 100 mPa · s (20 ° C.), more preferably 5 to 50 mPa · s (20 ° C.), and still more preferably 10 to 30 mPa · s (20 ° C.). . The viscosity can be adjusted by adjusting the power of the disperser and the mixing ratio of the water-insoluble dispersant, pigment, and organic solvent.
From the viewpoint of stabilizing the quality of the pigment dispersion and stabilizing the production conditions during the production of the color filter, it is preferable that the average particle diameter or viscosity does not change before and after storage of the pigment dispersion.
The rate of change in particle size is preferably 110% or less, more preferably 105% or less, and even more preferably 100%. The viscosity change rate is preferably 110% or less, more preferably 105% or less, and still more preferably 100%.

<Pigment dispersion for color filter>
The pigment dispersion for a color filter obtained by the production method of the present invention has a high contrast ratio due to the small number of coarse particles, and also has a low dispersion viscosity and excellent storage stability. It is useful as a coloring composition for color filters. That is, by adding and mixing various binders, polyfunctional monomers, photopolymerization initiators or thermosetting compounds, solvents, additives, etc., it can be used as a color filter coloring composition (color resist coloring material). .
Examples of the binder include a copolymer of (meth) acrylic acid and (meth) acrylic ester, a styrene / maleic anhydride copolymer, a reaction product of a styrene / maleic anhydride copolymer and an alcohol, and the like. Can do. The weight average molecular weight is preferably 5000 to 200,000. The content of the binder is preferably 20 to 80% by weight with respect to the total solid content in the pigment dispersion composition.
Examples of the polyfunctional monomer include (meth) acrylic acid ester, urethane (meth) acrylate, (meth) acrylic acid amide, allyl compound, and vinyl ester having two or more ethylenically unsaturated double bonds. The content of the polyfunctional monomer is preferably 10 to 60% by weight with respect to the total solid content in the pigment dispersion composition.

Examples of the photopolymerization initiator include aromatic ketones, lophine dimers, benzoin, benzoin ethers, and polyhalogens. In particular, a combination of 4,4′-bis (diethylamino) benzophenone and 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 4- [pN, N-di (ethoxycarbonylmethyl) -2, 6-di (trichloromethyl) -s-triazine] is preferred. A photoinitiator can be used individually or in combination of 2 or more types. The content of the photopolymerization initiator is preferably 0.2 to 20% by weight with respect to the total solid content in the pigment dispersion composition.
The thermosetting compound is not particularly limited as long as the film is cured by heating, and a compound having a thermosetting functional group can be used. For example, those having at least one group selected from an epoxy group, a methylol group, an alkoxymethyl group, and an acyloxymethyl group are preferable. A thermosetting compound can be used individually or in combination of 2 or more types. The content of the thermosetting compound is preferably 0.1 to 15% by weight with respect to the total solid content in the pigment dispersion composition.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.
Measurement of the dispersion physical properties (average particle size, viscosity, contrast ratio) obtained in Examples and Comparative Examples and evaluation of storage stability (particle size change rate, viscosity change rate) were performed by the following methods.
(1) Measurement of average particle size (D50) The particle size immediately after the preparation of the pigment dispersion was measured using a particle size analyzer (ZETSIZER Nano-ZS, manufactured by Sysmex Corporation), and 50% passing particles in the volume average particle size distribution. The diameter (D50) was defined as the average particle diameter.
The particle size was measured at 20 ° C. using the above particle size analyzer after diluting the pigment dispersion 300 times with diethylene glycol monobutyl ether acetate (BCA). In addition, the dispersoid refractive index: 1.51, the dispersoid density: 1.45 g / cm ³ , the dispersion medium refractive index: 1.43, and the dispersion medium viscosity: 3.6 cps were used.
The average particle size is preferably small and more preferably 60 nm or less.
(2) Viscosity measurement The viscosity immediately after preparation of the pigment dispersion was measured using an E-type viscometer [measurement temperature: 20 ° C., measurement time: 1 minute, rotation speed: 20 rpm, standard rotor (1 ° 34 ′ × R24)] ( The viscosity was measured using Toki Sangyo Co., Ltd., TV-25).
The viscosity is preferably small.
(3) Measurement of contrast ratio After applying a pigment dispersion composition with a pigment concentration adjusted to 10% on a glass substrate using a spin coater, the pigment dispersion composition was allowed to stand for 5 minutes on a horizontal platform and dried on a hot plate at 80 ° C for 15 minutes. Create a paint film. Next, the contrast ratio of the obtained coating film was measured with a contrast measuring instrument (CT-1 manufactured by Aisaka Electric Co., Ltd.).
The larger the contrast ratio value, the better the contrast.

(4) Evaluation of particle size stability The average particle size immediately after preparation of the target pigment dispersion (pigment dispersion obtained in the second step) (before storage) was measured according to (1) above. Similarly, the average particle diameter after storing the pigment dispersion at 40 ° C. for one week was measured, and the change in the average particle diameter before and after storage was compared. And storage stability was evaluated.
Change rate of particle diameter = [(average particle diameter after storage for 7 days) / (average particle diameter immediately after preparation (before storage))] × 100 (1)
(5) Evaluation of viscosity stability The viscosity immediately after preparing the target pigment dispersion (pigment dispersion obtained in the second step) (before storage) was measured according to (2) above. Similarly, the viscosity of the pigment dispersion after storage at 40 ° C. for 1 week is measured, the change in viscosity before and after storage is compared, the viscosity change rate is obtained by the following formula (2), and the storage stability is improved. evaluated.
Viscosity change rate = [(viscosity after 1 week storage) / (viscosity immediately after preparation (before storage)) × 100] (2)

Production Example 1 (Production of pigment mixture)
Adisper PB-821 (trade name, manufactured by Ajinomoto Fine Techno Co., Ltd .: basic urethane resin dispersant, amine value 9 mgKOH / g) is sufficiently dissolved in 82 parts of diethylene glycol monobutyl ether acetate (hereinafter referred to as “BCA”). A water-insoluble dispersant solution was prepared. Next, diketopyrrolopyrrole pigment (A) (manufactured by Dainichi Seika Kogyo Co., Ltd., CI Pigment Red 254, trade name “CHROMOFINE RED 6156” was passed through the tank jacket and stirred. ”, 10 parts of acrylic resin-treated pigment (copolymer based on benzyl methacrylate / methacrylic acid, weight ratio of pigment to acrylic resin (acrylic resin / pigment) is 0.1), and further 30 minutes The mixture was sufficiently stirred to obtain a pigment mixed solution (a) containing a pigment having an acrylic resin adsorbed on the surface.

Example 1
(1) Production of Preliminary Dispersion (1) The pigment mixture (a) obtained in Production Example 1 was mixed with a media-type disperser (manufactured by Nippon Coke Kogyo Co., Ltd., SC-320, mill volume 8.8 L, motor capacity. 30 kW) was used for the preliminary dispersion in the circulation operation. Here, the circulation operation is an operation method in which a container holding a mixed liquid, a circulation pump, and a media-type disperser are connected in this order, and the mixed liquid discharged from the discharge port of the disperser is returned to the container again. is there.
The operating conditions of the disperser at this time were as follows: φ0.3 mm zirconia beads (trade name “YTZ beads” manufactured by Nikkato Co., Ltd.) were used as media so that the filling rate was 72%, and the rotating peripheral speed of the disperser was 10 0.5 m / s, the liquid circulation flow rate was 720 kg / hr, and the temperature was around 15 ° C. At this time, the instantaneous power of the disperser was 0.96 kW / kg, and preliminary dispersion was performed until the integrated power was 4.8 kWh / kg (5 hours).
(2) Production of Pigment Dispersion (1) The preliminary dispersion (1) obtained in (1) above was further mixed with a media-type disperser (manufactured by Kotobuki Industries Co., Ltd., UAM-10, mill volume 6.6 L, motor Using a capacity of 22 kW), the main dispersion was carried out by circulation operation to obtain a pigment dispersion (1).
The operating conditions of the disperser at this time were as follows: φ0.05 mm zirconia beads (trade name “YTZ beads” manufactured by Nikkato Co., Ltd.) were used as media so that the filling rate would be 75%, and the rotating peripheral speed of the disperser was 8 m / s, the temperature was around 15 ° C. At this time, the instantaneous power of the disperser was 2.1 kW / kg, and the main dispersion was performed until the integrated power was 10.1 kWh / kg (4.8 hours). The results are shown in Table 1.

Example 2
(1) Production of Preliminary Dispersion (2) The above Example 1 (1) except that the pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed until the integrated power became 7.8 kWh / kg. Pre-dispersion was carried out under the same dispersion conditions.
(2) Production of Pigment Dispersion (2) The preliminary dispersion (2) obtained in (1) above is subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (2 ) The results are shown in Table 1.

Example 3
(1) Production of Preliminary Dispersion (3) The pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed by a circulation operation using a media-type disperser (SC-320). The operating conditions of the disperser at this time were as follows: φ0.3 mm zirconia beads (YTZ beads) were used as media so that the filling rate would be 70%, the disperser rotational speed was 12 m / s, and the liquid circulation flow rate was 720 kg / hr. At this time, the instantaneous power of the disperser was 1.5 kW / kg, and preliminary dispersion was performed until the integrated power was 4.8 kWh / kg.
(2) Production of Pigment Dispersion (3) The preliminary dispersion (3) obtained in (1) above is subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (3 ) The results are shown in Table 1.

Example 4
(1) Production of Preliminary Dispersion (4) Example 1 (1) above, except that the pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed until the integrated power reached 2.5 kWh / kg. Pre-dispersion was carried out under the same dispersion conditions.
(2) Production of Pigment Dispersion (4) The preliminary dispersion (4) obtained in (1) above is subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (4 ) The results are shown in Table 1.

Example 5
(1) Production of Preliminary Dispersion (5) Example 3 (1) above, except that the pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed until the integrated power reached 7.8 kWh / kg. Pre-dispersion was carried out under the same dispersion conditions.
(2) Production of Pigment Dispersion (5) The preliminary dispersion (5) obtained in (1) above is subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (5 ) The results are shown in Table 1.

Example 6
(1) Production of Pigment Dispersion (6) The preliminary dispersion (2) obtained in Example 2 (1) above was further subjected to circulation operation using a media-type disperser (UAM-10). Dispersion was performed to obtain a pigment dispersion (6). The operating conditions of the disperser at this time were φ0.05 mm zirconia beads (the YTZ beads) as media and a filling rate of 75%, and the rotating peripheral speed of the disperser was 10 m / s. At this time, the instantaneous power of the disperser was 2.9 kW / kg, and the main dispersion was performed until the integrated power was 10.3 kWh / kg. The results are shown in Table 1.

Example 7
(1) Production of Preliminary Dispersion (6) The pigment mixture (a) obtained in Production Example 1 was converted into a media-type disperser (Shinmaru Enterprises Co., Ltd., Dino Mill KD-8, mill volume 8 L, motor capacity. 22 kW) was preliminarily dispersed by circulation operation. The operating conditions of the disperser at this time were as follows: φ0.3 mm zirconia beads (YTZ beads) as media were filled so that the filling rate would be 60%, the rotating peripheral speed of the disperser was 8 m / s, and the liquid circulation flow rate was 450 kg / hr. At this time, the instantaneous power of the disperser was 0.9 kW / kg, and preliminary dispersion was performed until the integrated power was 3.7 kWh / kg.
(2) Production of Pigment Dispersion (7) The preliminary dispersion (6) obtained in (1) above was subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (7 ) The results are shown in Table 1.

Comparative Example 1
(1) Production of Preliminary Dispersion (7) The pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed by a circulation operation using a media type dispersing machine (SC-320). The operating conditions of the disperser at this time were as follows: φ0.3 mm zirconia beads (YTZ beads) as media were filled to a filling rate of 40%, the rotating peripheral speed of the disperser was 8 m / s, and the liquid circulation flow rate was 720 kg / hr. At this time, the instantaneous power of the disperser was 0.04 kW / kg, and preliminary dispersion was performed until the integrated power was 4.8 kWh / kg.
(2) Production of Pigment Dispersion (8) The preliminary dispersion (7) obtained in (1) above is subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (8 ) The results are shown in Table 1.

Comparative Example 2
(1) Production of Preliminary Dispersion (8) The pigment mixed liquid (a) obtained in Production Example 1 was preliminarily dispersed by a circulation operation using a media type disperser (SC-320). The operating conditions of the disperser at this time were as follows: φ0.3 mm zirconia beads (YTZ beads) as media were filled at a filling rate of 90%, the rotating peripheral speed of the disperser was 12 m / s, and the liquid circulation flow rate was 720 kg / hr. At this time, the instantaneous power of the disperser was 4 kW / kg, and preliminary dispersion was performed until the integrated power was 4.8 kWh / kg.
(2) Production of Pigment Dispersion (9) The preliminary dispersion (8) obtained in (1) above was subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (9 ) The results are shown in Table 1.

Comparative Example 3
(1) Production of Preliminary Dispersion (9) Example 1 (1) above, except that the pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed until the integrated power became 0.65 kWh / kg. Pre-dispersion was carried out under the same dispersion conditions.
(2) Production of Pigment Dispersion (10) The preliminary dispersion (9) obtained in (1) above is subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (10 ) The results are shown in Table 1.

Comparative Example 4
(1) Production of Preliminary Dispersion (10) Same as Example 1 (1) except that the pigment mixture (a) obtained in Production Example 1 was preliminarily dispersed until the integrated power reached 15 kWh / kg. Preliminary dispersion was performed under dispersion conditions.
(2) Production of Pigment Dispersion (11) The preliminary dispersion (10) obtained in (1) above was subjected to main dispersion under the same dispersion conditions as in Example 1 (2), and the pigment dispersion (11 ) The results are shown in Table 1.

Comparative Example 5
(1) Production of Pigment Dispersion (12) The pigment used is diketopyrrolopyrrole pigment (B) (manufactured by BASF, CI Pigment Red 254, trade name: “IRGAPHOR RED BK-CF”, acrylic resin The pigment mixture liquid (b) was obtained in the same manner as in Production Example 1, except that it was not contained. The pigment is the same as that used in the examples of JP 2011-57823 A.
Using the resulting pigment mixture (b), dispersion was performed under the same pre-dispersion and present dispersion conditions as in Example 2 to obtain a pigment dispersion (12). The results are shown in Table 1.

Comparative Example 6
(1) Production of Pigment Dispersion (13) The pigment used was diketopyrrolopyrrole pigment (C) (CI Pigment Red 254, manufactured by Toyo Ink SC Holding Co., Ltd., trade name: “LIONOGEN RED 4130”, A pigment mixed liquid (c) was obtained in the same manner as in Production Example 1 except that the alkali resin was not contained and the rosin resin was contained.
Using the obtained pigment mixed liquid (c), dispersion was carried out under the same pre-dispersion and main dispersion conditions as in Example 2 to obtain a pigment dispersion (13). The results are shown in Table 1.
Comparative Example 7
(1) Production of Pigment Dispersion (14) Diketopyrrolopyrrole pigment (D) (manufactured by Dainichi Seika Co., Ltd., CI Pigment Red 254, trade name: “CHROMOFINE RED”, containing acrylic resin) The pigment mixture liquid (d) was obtained in the same manner as in Production Example 1 except that
Using the obtained pigment mixed liquid (d), dispersion was carried out under the same pre-dispersion and main dispersion conditions as in Example 2 to obtain a pigment dispersion (14). The results are shown in Table 1.

From Table 1, the pigment dispersions of Examples 1 to 7 have a small average particle size and low viscosity, and also have a small increase in viscosity and a large increase in particle size after storage, and excellent storage stability. I understand that. Furthermore, it turns out that the contrast ratio of the coating film produced from these pigment dispersions is high.
On the other hand, from Comparative Example 1, if the instantaneous power of the first step (preliminary dispersion) is too small, the average particle size is not reduced, and from Comparative Example 2, as described in the examples of JP 2011-57823 A, conversely, It can be seen that if the instantaneous power is too large, the average particle size and viscosity increase, and the viscosity storage stability deteriorates.
From Comparative Example 3, if the integrated power in the first step (preliminary dispersion) is too small, the average particle size is not reduced. From Comparative Example 4, on the contrary, if the integrated power is too large, the average particle size and viscosity increase, It can be seen that the viscosity storage stability also deteriorates.
In addition, it can be seen from Comparative Examples 5 to 7 that when an organic pigment treated with an acrylic resin is not used, the average particle size does not decrease and the contrast ratio does not increase even if dispersion is performed under the dispersion conditions of the present invention.

  According to the present invention, it is possible to efficiently produce a pigment dispersion for a color filter that can finely disperse a pigment, has a low viscosity, and has excellent storage stability. Moreover, since the obtained pigment dispersion for color filters is excellent in heat resistance and contrast ratio, it can be suitably used as a color material for color filters such as liquid crystal display elements and solid-state imaging elements.

1: External fixed container 2: Separator 3: Cylindrical rotor 4: Liquid chamber 5: Outer chamber 6: Slit 7: Media particles 8: Supply port 9: Discharge port 10: Rotating shaft of rotor 11: Liquid discharge hole L: Length in the direction of the rotation axis in the external fixed container (1) D: Inner diameter of the external fixed container (1)

Claims (9)

The manufacturing method of the pigment dispersion for color filters which has the following 1st process and 2nd process.
First step: A mixed solution containing an organic pigment treated with an acrylic resin, a water-insoluble dispersant, and an organic solvent has an instantaneous power of 0.5 to 3 kW / kg and an integrated power of 2 to 12 kWh / kg. A step of pre-dispersing with a media-type disperser filled with media particles under the conditions;
Second step: A step of subjecting the preliminary dispersion obtained in the first step to a main dispersion treatment using a media-type disperser filled with media particles having a particle size smaller than that of the media particles in the first step.   The manufacturing method of the pigment dispersion for color filters of Claim 1 whose particle size of the media particle used in a 1st process is 0.1-1 mm.   The manufacturing method of the pigment dispersion for color filters of Claim 1 or 2 whose particle size of the media particle used in a 2nd process is 0.003-0.08 mm.   The method for producing a pigment dispersion for a color filter according to any one of claims 1 to 3, wherein the acrylic resin is a resin obtained by polymerizing a monomer mixture containing a (meth) acrylic acid monomer and a hydrophobic monomer. .   The manufacturing method of the pigment dispersion for color filters in any one of Claims 1-4 whose organic pigment is a diketopyrrolopyrrole pigment.   Either the water-insoluble dispersant used in the first step or the water-insoluble dispersant used in the second step is a basic urethane resin having an amine value of 3 to 20 mgKOH / g. The manufacturing method of the pigment dispersion for color filters of description.   The media-type disperser used in the first step has a cylindrical external fixed container (1), a separator (2) and a rotor (3) provided with the same axis in the inside, and the separator (2) The container (1) is divided into two in the radial direction to form a liquid chamber (4) and an outer chamber (5), and a plurality of slits (6) communicating between the two chambers are provided at least on the peripheral surface. The rotor (3) is rotatably provided inside the liquid chamber (4), the liquid chamber (4) is filled with media particles (7), and the liquid chamber (4) A disperser comprising a supply port (8) for supplying a mixed liquid and a discharge port (9) for discharging the mixed liquid from the outer chamber (5). The manufacturing method of the pigment dispersion for color filters of description.   In the first step, the liquid mixture (4) is supplied from the supply port (8) of the external fixed container (1) toward the rotor (3) while rotating the rotor (3) of the media type dispersing machine. The mixed liquid that has passed through the separator (2) via the media particles (7) inside is discharged as a dispersion from the outlet (9) of the container (1) by centrifugal force. Of manufacturing a pigment dispersion for color filter.   The media-type disperser used in the second step continuously disperses the preliminary dispersion obtained in the first step and continuously separates the obtained dispersion from the media. The manufacturing method of the pigment dispersion for color filters in any one of -8.

Images