JP2009057422A - Method for producing nonaqueous pigment dispersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a nonaqueous pigment dispersion that is micronized and has excellent dispersibility and storage stability and to obtain the nonaqueous pigment dispersion. <P>SOLUTION: The method for producing a pigment dispersion comprises a process 1 of mixing an organic solvent (A) with a graft polymer (B) having an SP value [solubility parameter (cal/cm<SP>3</SP>)<SP>1/2</SP>] being [SP value of the organic solvent (A)+1]-[SP value of the organic solvent (A)+3] and heat-treating the mixture to give a preliminary dispersion and a process 2 of dispersing a pigment (C) into the resultant preliminary dispersion, to give a pigment dispersion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a non-aqueous pigment dispersion and the non-aqueous pigment dispersion.

Traditionally, polymeric materials are known to be useful for dispersing pigments in non-aqueous solvents, and polymeric materials have been used to formulate non-aqueous pigment dispersions. Non-aqueous pigment dispersions are widely used, for example, as solvent paints for automobile exteriors and color filter inks for color liquid crystal displays. In particular, in the color filter field, high saturation and lightness are required to improve the quality of the color liquid crystal display, and the pigments in the color filter are also required to be miniaturized.
A pigment dispersion method is adopted as a method for producing a color filter. In this method, a color resist solution obtained by mixing a pigment dispersion and a photosensitive composition is applied onto a transparent substrate, and then exposed and cured to form a transparent substrate. A colored pattern is formed on top. In this pigment dispersion method, a surfactant and a dispersant are used to finely disperse the pigment.
With the miniaturization of pigments, dispersion performance and storage stability performance are greatly required.

  By the way, as a polymer used as a pigment dispersant, it is known that a graft polymer has good performance. For example, Patent Document 1 discloses a non-aqueous system including an organic pigment, a polymerizable oligomer having an ethylenically unsaturated double bond, and a monomer copolymer having a nitrogen atom-containing group and an ethylenically unsaturated double bond. A pigment dispersion is disclosed. However, Patent Document 1 does not suggest the technical idea of the present invention.

JP-A-10-339949

  An object of the present invention is to provide a method for producing a non-aqueous pigment dispersion that is miniaturized and excellent in dispersibility and storage stability, and the non-aqueous pigment dispersion.

In the improvement of the characteristics of the non-aqueous pigment dispersion, the present inventors paid attention to the fact that the solubility of the polymer and the momentum in the solution change due to the temperature change. First, the poorly soluble polymer was suspended in the solvent. After that, it was found that the above-mentioned problems can be solved by preparing a pre-dispersion in which the polymer is uniformly dispersed in the solvent by heat treatment and dispersing the pigment therein.
That is, the present invention provides the following (1) and (2).
(1) A method for producing a pigment dispersion comprising the following step 1 and step 2.
Step 1: Organic solvent (A) and SP value [solubility parameter (cal / cm ³ ) ^1/2 ] are [SP value of organic solvent (A) +1] to [SP value of organic solvent (A) +3]. Step of mixing a certain graft polymer (B) and obtaining a pre-dispersion by heat treatment Step 2: Step of adding a pigment (C) to the obtained pre-dispersion and dispersing to obtain a pigment dispersion (2 ) A non-aqueous pigment dispersion obtained by the production method of (1).

  ADVANTAGE OF THE INVENTION According to this invention, even if it refines | miniaturizes, the manufacturing method of the non-aqueous pigment dispersion excellent in the dispersibility and the storage stability, and the non-aqueous pigment dispersion can be provided.

The method for producing a non-aqueous pigment dispersion of the present invention includes the following step 1 and step 2.
Step 1: Organic solvent (A) and SP value [solubility parameter (cal / cm ³ ) ^1/2 ] are [SP value of organic solvent (A) +1] to [SP value of organic solvent (A) +3]. Step of mixing a certain graft polymer (B) and obtaining a pre-dispersion by heat treatment Step 2: Adding pigment (C) to the obtained pre-dispersion and obtaining a pigment dispersion by dispersing treatment Each component and each process used for this invention are demonstrated.

[Organic solvent (A)]
Although the organic solvent (A) used in the present invention is not particularly limited, a high boiling point organic solvent having a boiling point of 70 ° C. or higher, more preferably 100 ° C. or higher is particularly preferable when used as an oil-based ink for a color filter. From the viewpoint of dispersibility of the pigment (C) and the viewpoint of making the pigment dispersion oily, the SP value (solubility parameter) of the organic solvent (A) is preferably 8 to 9 (cal / cm ³ ) ^{1 / 2} and more preferably 8.4 to 8.9 (cal / cm ³ ) ^1/2 . The SP value of the organic solvent (A) can be calculated by the Fedors method [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)].

  Specific examples of such an organic solvent (A) include cellosolves, carbitols, alcohols and the like, and compounds represented by the following general formula (1).

(In the formula, R ¹ and R ² each independently represent a linear or branched alkyl group having 1 to 4 carbon atoms, and R ³ represents a hydrogen atom or a methyl group.)
Examples of cellosolves include ethylene glycol alkyl ethers such as ethylene glycol monomethyl ether, ethylene glycol diethyl ether, and ethylene glycol monoethyl ether. Examples of carbitols include diethylene glycol alkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, and diethylene glycol monoethyl ether. Examples of alcohols include ethylene glycol, diethylene glycol, glycerin and the like.
Among the above, the compound represented by the general formula (1) is preferable.

In the general formula (1), the linear or branched alkyl group having 1 to 4 carbon atoms of R ¹ and R ² includes a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. Groups, sec-butyl groups, and tert-butyl groups. In these, a methyl group and an ethyl group are preferable.
Examples of the compound represented by the general formula (1) include (i) ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether propionate, ethylene glycol monoethyl ether propionate, propylene glycol. Alkanediyl glycol monoalkyl ether acetates such as monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether propionate, propylene glycol monoethyl ether propionate, diethylene glycol monomethyl ether acetate, (ii) propylene glycol monomethyl ether, Alkanediyl such as propylene glycol dimethyl ether Recall dialkyl ether, and the like.
Among these, alkanediyl glycol monoalkyl ether acetate is preferable from the viewpoint of the solubility or dispersibility of the graft polymer (B) and the dispersibility of the pigment (C), particularly the diketopyrrolopyrrole pigment, and propylene glycol monomethyl. Ether acetate (PGMEA, SP value 8.73, boiling point 145 ° C.) is more preferable.
An organic solvent (A) can be used individually or in combination of 2 or more types.

[Graft polymer (B)]
In the present invention, as a graft polymer (B), the SP value SP value [solubility parameter (cal / cm ^{3) 1/2]} [SP value + organic solvent (A)] - is [Organic solvent (A) +3 ] Is used. The SP value of the graft polymer (B) is preferably 10 to 12 (cal / cm ³ ) ^1/2 , more preferably 10.5 to 11.5 (cal / cm ³ ) ^1/2. The SP value (solubility parameter) of the polymer is represented by the square root of the ratio between the cohesive energy density and the molecular volume, as shown by the following formula.
SP value ((cal / cm ³ ) ^1/2 ) = (ΔE / ΔV) ^1/2
In the above formula, ΔE represents the cohesive energy density, and ΔV represents the molecular volume. The value can be calculated by the method of Fedors [Robert F. Fedors, Polymer Engineering and Science, 14, 147-154 (1974)].
For example, the graft polymer (B) is dimethylacrylamide / 2-hydroxyethyl methacrylate / poly (meth) acrylic acid methyl macromer having a (meth) acryloyl group at one end (weight ratio) = 10/10/80 graft polymer ( SP value is calculated as follows when the product name is AA-6, manufactured by Toa Gosei Co., Ltd.
SP value of dimethylacrylamide homopolymer is 10.08 (monomer is 8.81), SP value of 2-hydroxyethyl methacrylate homopolymer is 13.47 (monomer is 12.06), poly (meth) acrylate methyl macromer Since the SP value is calculated as 10.08, the SP value of the obtained graft polymer (B) is 10.08 × 0.1 + 13.47 × 0.1 + 10.08 × 0.8 = 10.42.
It becomes.
This graft polymer (B) is used as a dispersant for stably dispersing the pigment (C), particularly a diketopyrrolopyrrole pigment, and is considered to function as a binder when forming a color filter or the like. It is done.
The graft polymer (B) preferably has the following structural units (b1), (b2) and (b3). Hereinafter, each of these structural units will be described.

[Structural unit (b1)]
The structural unit (b1) is a monomer having an ethylenically unsaturated double bond and a nitrogen atom (hereinafter sometimes referred to as “nitrogen-containing monomer (b1-1)”) or a structural unit derived from a polymer containing a nitrogen atom. Preferably, it is derived from a polymerizable macromonomer having an ethylenically unsaturated double bond at one end and further containing a nitrogen atom (hereinafter sometimes referred to as “nitrogen-containing macromonomer (b1-2)”). It is a structural unit. The structural unit (b1) is considered to have a function of adsorbing the graft polymer (B) to the pigment (C).
As the nitrogen-containing macromonomer (b1-2), a polymer of a monomer having an ethylenically unsaturated double bond and a nitrogen atom, poly (N-acylalkanediylimine) having an ethylenically unsaturated double bond at one end Is mentioned.

Examples of the monomer having an ethylenically unsaturated double bond and a nitrogen atom include vinylpyridines, nitrogen-containing styrene monomers, (meth) acrylamides, nitrogen-containing (meth) acrylic acid esters; N-vinylpyrrolidone and the like.
Examples of vinylpyridines include 2-vinylpyridine and 4-vinylpyridine, and examples of nitrogen-containing styrene monomers include p-styrenesulfonamide, p-aminostyrene, and aminomethylstyrene.
As (meth) acrylamides, (meth) acrylamide, N, N-dialkyl (meth) acrylamide having an alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, 1 to 8 carbon atoms, preferably carbon N-alkyl (meth) acrylamide having an alkyl group having 1 to 4 carbon atoms, N, N-dialkylaminoalkyl having an alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms (preferable carbon number 1 for alkyl group) -6) (meth) acrylamide, (meth) acrylamide 2-methylpropylsulfonic acid, morpholino (meth) acrylamide, piperidino (meth) acrylamide, N-methyl-2-pyrrolidyl (meth) acrylamide, N, N-methylphenyl ( And (meth) acrylamide.
The nitrogen-containing (meth) acrylic acid ester is an N, N-dialkylaminoalkyl having an alkyl group having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms (preferably having 1 to 6 carbon atoms in the alkyl group) (meth). Acrylate, 1- (N, N-dialkylamino) -1,1-dimethylmethyl (meth) acrylate having 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms, morpholinoethyl (meth) acrylate, piperidinoethyl Nitrogen-containing (meth) acrylates such as (meth) acrylate, 1-pyrrolidinoethyl (meth) acrylate, N, N-methyl-2-pyrrolidylaminoethyl (meth) acrylate, N, N-methylphenylaminoethyl (meth) acrylate ) Acrylic acid ester; N-vinylpyrrolidone and the like.

  The poly (N-acylalkanediylimine) having an ethylenically unsaturated double bond at one end has a (meth) acryloyl group or styryl group at one end and is a structural unit represented by the general formula (2) And poly (N-acylalkanediylimine).

In the formula (2), R ⁴ represents an alkyl group, alkenyl group, aralkyl group or aryl group having 1 to 22 carbon atoms, preferably 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and n is 2 or An integer of 3 is shown.
Examples of such poly (N-acylalkanediylimine) include those obtained by cationic ring-opening polymerization of 2-alkyloxazoline or 2-alkyloxazine as described in Japanese Patent No. 2643403.

Among these nitrogen-containing macromonomers (b1-2), one-terminal (meth) acryloyl type nitrogen atom-containing polymerizable macromonomers are preferable. Specific examples thereof include one-terminal (meth) acryloyl type poly (N-acyl (acyl group having 2 to 9 carbon atoms) alkanediyl (alkanediyl group having 2 to 3 carbon atoms imine), poly (N-alkyl). (Alkyl group having 1 to 8 carbon atoms) (meth) acrylamide), poly (N, N-dialkyl (alkyl group having 1 to 8 carbon atoms) (meth) acrylamide), and poly (N-vinylpyrrolidone).
Among these, one-terminal (meth) acryloyl type poly (N-acyl (acyl group having 2 to 4 carbon atoms) alkanediyl (alkanediyl group having 2 to 3 carbon atoms) imine), poly (N, N- Dimethylacrylamide) and poly (N-vinylpyrrolidone) are more preferable. One-terminal methacryloyl type poly (N-acyl (acyl group having 2 to 4 carbon atoms) alkanediyl (alkanediyl group having 2 to 3 carbon atoms) imine) Is more preferable, and one-terminal methacryloyl type poly (2-ethyloxazoline) is particularly preferable.
In the present specification, (meth) acryl means acryl or methacryl, (meth) acrylate means acrylate or methacrylate, and (meth) acryloyl means acryloyl or methacryloyl.
The weight average molecular weight of the nitrogen-containing macromonomer (b1-2) is preferably 300 to 30,000, more preferably 400 to 20,000, and particularly preferably 500 to 10,000.

[Structural unit (b2)]
The structural unit (b2) is a structural unit derived from a polymer not containing a nitrogen atom, and preferably has a polymerizable macromonomer having an ethylenically unsaturated double bond at one end and not containing a nitrogen atom (hereinafter “ It is a structural unit derived from (sometimes referred to as “macromonomer (b2)”). The structural unit (b2) is considered to have a function of stably dispersing the graft polymer (B) in the organic solvent (A).
As the macromonomer (b2), a macromonomer having a (meth) acryloyl group or a styryl group at one end is preferable. Preferable examples thereof include polystyrene, alkyl poly (meth) acrylates such as methyl poly (meth) acrylate, poly (meth) acrylate n-butyl, poly (meth) acrylate isobutyl, etc. There can be mentioned a macromonomer in which a (meth) acryloyl group is bonded to one end of the molecule (4).
The weight average molecular weight of the macromonomer (b2) is preferably 500 to 30,000, more preferably 500 to 20,000, and particularly preferably 500 to 15,000.
Commercially available products of such polymerizable macromonomers include one-end methacryloyl-type polystyrene (number average molecular weight 6,000, trade name AS-6, manufactured by Toagosei Co., Ltd.), one-end methacryloyl-type polymethyl methacrylate (number-average). Molecular weight 6,000, weight average molecular weight 12,000, trade name AA-6, manufactured by Toagosei Co., Ltd., and one-terminal methacryloyl polyacrylate n-butyl (number average molecular weight 6,000, trade name AB-6, Toa Gosei Co., Ltd.).

[Structural unit (b3)]
The structural unit (b3) includes a nitrogen-containing monomer (b1-1) or a nitrogen-containing macromonomer (b1-2), and a monomer having an ethylenically unsaturated double bond copolymerizable with the macromonomer (b2) (hereinafter “ Monomer (b3) ”)). The structural unit (b3) is considered to have a function of suppressing the dissolution of the pigment. The structural unit (b3) is a backbone unit in the graft polymer (B), in which the structural unit (b1) is bonded to one side and the structural unit (b2) is bonded to the other side.

The monomer (b3) preferably has a hydrophobic group, and examples of the hydrophobic group include an alkyl group having 4 or more carbon atoms, preferably 6 or more carbon atoms, a fluorine-containing alkyl group, and an alkylsiloxy group.
Examples of the monomer having an alkyl group having 4 or more carbon atoms include alkyl (meth) acrylates having 4 or more carbon atoms. More specifically, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, dodecyl (meth) acrylate, stearyl (meth) acrylate (SP value 8.67), methacrylic acid ( SP value 10.73), acrylic acid (SP value 11.08), dimethylacrylamide (SP value 10.59), acrylamide (SP value 10.64), 2-hydroxyethyl acrylate (SP value 12.45), 2 -Hydroxyethyl methacrylate (SP value 12.06), glycerol monomethacrylate (SP value 13.30), etc. are mentioned, and 2-hydroxyethyl methacrylate (HEMA, SP value 12.06) is preferable.

Examples of the monomer having a fluorine-containing alkyl group include fluoro (meth) acrylate and perfluoro (meth) acrylate. More specifically, 2,2,2-trifluoroethyl (meth) acrylate, 2,2,3,3,3-pentafluoropropyl (meth) acrylate, 2- (perfluorobutyl) ethyl (meth) acrylate 2- (perfluorohexyl) ethyl (meth) acrylate, 2- (perfluorooctyl) ethyl (meth) acrylate, 2- (perfluorodecyl) ethyl (meth) acrylate, and the like.
Examples of the monomer having an alkylsiloxy group include monomers having a dimethylsiloxy group and a trimethylsiloxy group, and specific examples thereof include silicone macromonomers represented by the following general formulas (3) to (6). .

In said formula (3)-(6), R < ⁵ > shows a hydrogen atom or a methyl group, R < ⁶ > -R < ¹⁴ > shows a C1-C4 alkyl group or a C1-C4 alkoxy group, respectively. n is a number of 1 to 100, preferably 1 to 50, more preferably 1 to 20.
In these, the silicone macromonomer represented by General formula (6) is preferable.

The graft polymer (B) used in the present invention may have a graft chain containing other structural units in the structural units (b1), (b2) and (b3).
The graft polymer (B) is, for example, a monomer mixture containing at least one selected from a nitrogen-containing monomer (b1-1) and a nitrogen-containing macromonomer (b1-2), a macromonomer (b2), and a monomer (b3). It can be obtained by copolymerization.
Examples of the method for producing the graft polymer (B) include a bulk polymerization method, a solution polymerization method, and a suspension polymerization method, and among them, the solution polymerization method is particularly preferable.
Solvents used in the solution polymerization method include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone and methyl ethyl ketone, esters such as ethyl acetate and butyl acetate, hydrocarbons such as hexane and cyclohexane, diethyl ether and tetrahydrofuran And ethers such as benzene, toluene and the like, and halogenated hydrocarbons such as dichloromethane and chloroform.

The ratio of the structural unit (b1) to the total structural units in the graft polymer (B) is preferably 2 to 50% by weight from the viewpoint of enhancing the adsorptivity to the pigment and obtaining good dispersion stability of the pigment. More preferred is 45% by weight.
The ratio of the structural unit (b2) to the total structural unit in the graft polymer (B) is preferably 20 to 95% by weight, more preferably 30 to 90% by weight, from the viewpoint of increasing dispersibility in the organic solvent (A). 40 to 85% by weight is particularly preferable.
The proportion of the structural unit (b3) to the total structural units in the graft polymer (B) is preferably 3 to 50% by weight, and 5 to 40% from the viewpoint of promoting the fixation of the graft polymer (B) to the pigment surface. % Is more preferable, and 7 to 35% by weight is particularly preferable.
The weight average molecular weight of the graft polymer (B) is preferably from 5,000 to 100,000, more preferably from 10,000 to 70,000.
The weight average molecular weight (Mw) of the nitrogen-containing macromonomer (b1-2), macromonomer (b2), and graft polymer (B) was measured by gel permeation chromatography (GPC) method using polystyrene as a standard substance. Details are described in the Examples.

[Pigment (C)]
The pigment used in the present invention may be either an inorganic pigment or an organic pigment. If necessary, these and extender pigments can be used in combination.
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Examples of extender pigments include silica, calcium carbonate, and talc. Examples of organic pigments include azo pigments, phthalocyanine pigments, condensed polycyclic pigments, and lake pigments.
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. Indigo pigments such as CI Pigment Red 88; I. Metal complex pigments such as C.I. Pigment Green 8; I. Pigment Red 254, 255, 264, 270, 272, C.I. I. And diketopyrrolopyrrole pigments such as CI Pigment Orange 71 and 73.
Among these, diketopyrrolopyrrole pigments represented by the following general formula (7) are preferable.

In formula (1), X ¹ and X ² each independently represent a hydrogen atom or a halogen atom, and Y ¹ and Y ² each independently represent a hydrogen atom, a —SO ₃ H group or a —CN group. Indicates.
Among diketopyrrolopyrrole pigments, C.I. I. CI Pigment Red 254 is preferable, and commercially available products such as “Irgaphor RED BT-CF”, “Irgaphor RED B-CF”, “Irgazin DPP Red BO”, “Irgazin Red” manufactured by Ciba Specialty Chemicals Co., Ltd. “2030”, “Irgazin DPP Red BOX”, “Irgazin Red BTR”, “Chromophthal DPP Red BP”, “Chromophthal DPP Red BOC”, “Microlith DPP Red B-K / Kli”, “A” “Microlen Red2028-MC”, “Microlen Red2030-MC” and the like can be mentioned.
The said pigment (A) can be used individually or in combination of 2 or more types.

[Method for producing non-aqueous pigment dispersion]
The non-aqueous pigment dispersion of the present invention is a non-aqueous pigment dispersion in which the graft polymer (B) is firmly fixed on the surface of the pigment (C) according to the production method including the following step 1 and step 2. It can be efficiently manufactured as a body.
Step 1: Organic solvent (A) and SP value [solubility parameter (cal / cm ³ ) ^1/2 ] are [SP value of organic solvent (A) +1] to [SP value of organic solvent (A) +3]. Step of mixing a certain graft polymer (B) and obtaining a pre-dispersion by heat treatment Step 2: Step of adding the pigment (C) to the obtained pre-dispersion and dispersing to obtain a pigment dispersion

[Step 1]
In step 1, the organic solvent (A) and the graft polymer (B) are mixed and heat-treated to obtain a preliminary dispersion. The organic solvent (A) and the graft polymer (B) are as described above.
There is no restriction | limiting in particular in the mixing method of an organic solvent (A) and a graft polymer (B), It can disperse | distribute using a well-known disperser, a kneader, etc. For example, kneaders such as paint shakers, roll mills, bead mills, kneaders, extruders, etc., high-pressure homogenizers (Izumi Food Machinery Co., Ltd., trade name), and homo-valve type high-pressure homogenizers typified by Minilab 8.3H type (Rannie, trade name) , Microfluidizer (trade name), Nanomizer (trade name), Ultimateizer (Sugino Machine Co., trade name), Genus PY (trade name, Hakusui Chemical Co., Ltd.), DeBEE2000 (Japan BEE) Chamber type high-pressure homogenizer, etc. A plurality of these devices can be combined. Among these, a paint shaker and a high-pressure homogenizer are preferable from the viewpoint of finer pigments.
The temperature of the heat treatment is not particularly limited, but is preferably 40 to 150 ° C, more preferably 60 to 130 ° C from the viewpoint of uniformly dispersing the graft polymer (B) in the organic solvent (A).

[Step 2]
In step 2, the pigment (C) is added to the preliminary dispersion obtained in step 1, and dispersion treatment is performed to obtain a pigment dispersion. The pigment (C) is as described above.
There is no particular limitation on the dispersion method of the preliminary dispersion obtained in step 1 and the pigment (C), and the above-described preliminary dispersion and pigment (C) are prepared using the known disperser, kneader and the like described in step 1. Can be wet dispersed.
Among these, a media type dispersing machine such as a sand mill is preferable. The media-type disperser retains media particles in a dispersion chamber (mill) and disperses them while applying dispersion energy such as pulverization, shearing, and collision with the media particles to the pre-dispersion of the pigment flowing therethrough. Thus, the media particles and the dispersion-treated product are separated by centrifugation or the like, and only the dispersion-treated product is allowed to flow out of the dispersion chamber. The sand mill is preferably a continuous type, and a roller mill type, a kneader type, a pin mixer type, or the like can be used.
Examples of the material of the media particles used in the media-type disperser include high-hardness metals such as glass, steel, and chromium alloys, high-hardness ceramics such as alumina, zirconia, zircon, and titania, and polymers such as ultra-high molecular weight polyethylene and nylon Materials and the like. The particle diameter (diameter) of the media particles is usually 30 to 500 μm, preferably 30 to 300 μm, from the viewpoint of improving the dispersibility of the pigment (C).
The weight ratio of media particles / dispersion (dispersion containing all of organic solvent (A), graft polymer (B), pigment (C), etc.) in the wet pulverization dispersion is from the viewpoint of dispersion stability of pigment (C). The ratio is usually 10/1 to 4/6, preferably 5/1 to 1/1.
It is preferable that the temperature of the dispersion process in the step 2 is a low temperature not higher than the heat treatment temperature in the process 1. More specifically, the dispersion treatment is preferably performed at 0 to 80 ° C, more preferably 0 to 40 ° C. The dispersion time is preferably 1 to 15 hours, more preferably 1 to 5 hours. After the dispersion treatment under such conditions, if the media particles are removed, the graft polymer (B) contained in the uniform preliminary dispersion obtained in step 1 is firmly fixed on the surface of the pigment (C). A non-aqueous pigment dispersion can be obtained.

[Non-aqueous pigment dispersion]
The non-aqueous pigment dispersion of the present invention contains an organic solvent (A), a graft polymer (B), and a pigment (C), and the proportions thereof are as follows from the viewpoint of storage stability and the like.
The content of the organic solvent (A) is preferably 20 to 95% by weight, more preferably 30 to 92% by weight, and further preferably 40 to 90% by weight. The content of the graft polymer (B) is preferably 2 to 30% by weight, and more preferably 2 to 40% by weight. The content of the pigment (C) is preferably 3 to 50% by weight, more preferably 4 to 40% by weight, and further preferably 5 to 40% by weight.
The volume median particle size (D50) of the pigment (C) in the pigment dispersion is preferably 20 to 150 nm, more preferably 30 to 140 nm in order to obtain a good contrast when used as a color material for a color filter. More preferably, it is 40-130 nm.
In the present invention, the volume median particle size (D50) means a particle size in which the cumulative volume frequency calculated by the volume fraction is 50% cumulative from the small particle size side. The volume median particle size (D50) in the present invention can be determined by the method described in the examples.
The viscosity (25 ° C.) at a solid content of 20% by weight of the non-aqueous pigment dispersion of the present invention is preferably 1 to 200 mPa · s, and preferably 1 to 100 mPa · s in order to obtain a favorable viscosity when used as a color filter color material. s is more preferable. Moreover, in order to maintain the favorable discharge property at the time of manufacturing a color filter by the inkjet method, 1-50 mPa * s is preferable and 1-30 mPa * s is more preferable.

The pigment dispersion of the present invention is excellent in storage stability even when the pigment is miniaturized, and can be effectively used as a color material for a color filter. When used for a color filter, in addition to the above components, a binder, a polyfunctional monomer, a photopolymerization initiator, and the like can be contained.
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 5,000 to 200,000. The content of the binder in the non-aqueous pigment dispersion of the present invention is preferably 20 to 80% by weight with respect to the total solid content.
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 in the pigment dispersion of the present invention is preferably 10 to 60% by weight with respect to the total solid content.
Examples of the photopolymerization initiator include aromatic ketones, lophine dimers, benzoin, benzoin ethers, and polyhalogens, and these can be used alone or in combination. 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. The content of the photopolymerization initiator in the non-aqueous pigment dispersion of the present invention is preferably 0.2 to 10% by weight with respect to the total solid content.
Furthermore, a solvent such as cyclohexanone, ethyl cellosolve acetate, ethylene glycol diethyl ether, or ethyl acetate can be added from the viewpoint of adjusting the viscosity to enable uniform coating film formation and enhancing storage stability.

In the following production examples, examples and comparative examples, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified. In addition, the measurement methods of the weight average molecular weight of the macromonomer and the polymer, the volume median particle size of the pigment dispersion, and the adsorption rate of the polymer on the pigment surface are as follows.
(1) Measurement of weight average molecular weight (Mw) of macromonomer A standard KPC method using a KF-804L column manufactured by Showa Denko KK as a column and chloroform added with 1 mmol / L of C12 dimethylamine as a solvent was used as a standard. Measurements were made using polystyrene as the material.
(2) Measurement of weight average molecular weight (Mw) of polymer N, N- containing 60 mmol / L phosphoric acid and 50 mmol / L lithium bromide as a solvent using an α-M column manufactured by Tosoh Corporation as a column. The measurement was carried out using polystyrene as a standard substance by the GPC method using dimethylformamide.
(3) Evaluation of storage stability The viscosity immediately after preparation of the pigment dispersion (before storage) was measured using a B-type viscometer (rotor No. 2, 60 rpm, 25 ° C.). Similarly, the viscosity after storing the pigment dispersion at 30 ° C. for 5 days was measured, and the storage stability (dispersion stability) was evaluated by the following formula by comparing the viscosity change before and after storage.
Storage stability = viscosity after storage for 5 days / viscosity immediately after preparation (before storage) (4) measurement of volume-median particle size (D50) of pigment dispersion The pigment dispersion immediately after production was diluted 300 times with PGMEA. , D50 was measured using a particle size analyzer (HONEYWELL, Microtrac UPA MODEL: 9340-UPA). As measurement conditions, diketopyrrolopyrrole pigment particle refractive index: 1.51, diketopyrrolopyrrole pigment density: 1.45 g / cm ³ , propylene glycol monomethyl ether acetate (PGMEA) refractive index: 1.40, PGMEA viscosity : 1.081 cP was input.
It shows that it is excellent in the dispersibility, so that the value of D50 is small.
(5) Measurement of adsorption rate of polymer to pigment surface The pigment dispersion was diluted with propylene glycol monomethyl ether acetate (PGMEA) to a pigment concentration of 5%, and centrifuged (Hitak Koki Co., Ltd., himac CP56G). ) For 3 hours at 30000 rpm, and then the solid content of the supernatant before and after centrifugation is measured using an infrared moisture meter (FD-240, manufactured by Kett Scientific Laboratory). The adsorption rate of the polymer to the pigment surface was calculated from the equation. The adsorption rate (%) is preferably higher as long as the pigment dispersion has a low viscosity and good dispersion stability.

Synthesis Example 1 [One-terminal methacryloyl-type poly (2-ethyloxazoline): synthesis of nitrogen-containing macromonomer (b1)]
An eggplant flask was charged with 300 g of dehydrated ethyl acetate and 132 g of 2-ethyloxazoline, and 65 g of a synthetic zeolite-based adsorbent (trade name “Zeolam A-4” manufactured by Tosoh Corporation) was added, stirred for 4 hours at room temperature, and filtered. The adsorbent was removed to obtain a dehydrated 2-ethyloxazoline solution.
Next, 380 g of the prepared dehydrated 2-ethyloxazoline solution and 17.9 g of diethylsulfuric acid were charged into a four-necked flask equipped with a reflux condenser, a thermometer, a nitrogen gas inlet tube, and a stirrer and replaced with dry nitrogen. Then, it stirred at 80 degreeC for 12 hours. After cooling the reaction solution to 40 ° C. or less, N, N-dimethylaminoethyl methacrylate previously dehydrated with the adsorbent was added, stirred for 4 hours at room temperature, reprecipitated and collected in a large amount of hexane. A one-terminal methacryloyl-type poly (2-ethyloxazoline) macromonomer was obtained. The resulting macromonomer had a weight average molecular weight of 1,000 and a number average molecular weight of 760. Since 6 units of 2-ethyloxazoline unit are introduced into this macromonomer, the SP value of this macromonomer is calculated to be 9.82. (The linked quaternary salt moiety was calculated as tertiary.)

Production Example 1 [Production of polymer (B-1)]
As the nitrogen-containing macromonomer (b1), 5 g (0.01 mol, SP value is 9.82) of the one-end methacryloyl-type poly (2-ethyloxazoline) macromonomer obtained in Synthesis Example 1 and the macromonomer (b2) , One-end methacryloyl polymethyl methacrylate (number average molecular weight 6,000, weight average molecular weight 12,000, trade name AA-6, manufactured by Toa Gosei Co., Ltd., SP value by calculation is 10.08) 65 g (0.0108 mol) ), 2-hydroxyethyl methacrylate (HEMA, manufactured by Wako Pure Chemical Industries, Ltd., the calculated homopolymer SP value is 13.47) 30 g (0.231 mol), and methyl ethyl ketone (MEK) as the solvent ) 75 g, isopropanol (IPA) 75 g, and 2,2′- as a polymerization initiator A solution (monomer concentration of 40%) in which 2 g of azobis (2,4-dimethylvaleronitrile) (Wako Pure Chemical Industries, Ltd., V-65) was mixed was prepared.
A volume of 10% of this mixed solution was charged into a 500 ml glass flask equipped with a stirrer, a dropping funnel and a nitrogen gas inflow tube, and after nitrogen replacement, the remaining mixed solution was stirred for 1 hour while stirring at 75 ° C. The polymer was polymerized by dropping.
The obtained polymer solution was diluted 10 times with a mixed solvent of MEK / IPA = 1/1 (weight ratio), and the solution was dropped into the 7-fold amount of hexane solvent to reprecipitate the polymer. The obtained polymer was dried and powdered to obtain a copolymer polymer of poly (2-hydroxyethyl methacrylate-g- (2-ethyloxazoline) -g-methyl methacrylate). The weight average molecular weight of this polymer (B-1) was 44,200.
The SP value of this polymer (B-1) was 11.08 as described below.
13.47 × (30/100) + 9.82 × (5/100) + 10.08 × (65/100) = 11.08
The results are shown in Table 1.

Production Example 2 [Production of polymer (B-2)]
As the nitrogen-containing macromonomer (b1), 2.5 g (0.005 mol, SP value is 9.82) of the one-end methacryloyl-type poly (2-ethyloxazoline) macromonomer obtained in Synthesis Example 1, and the macromonomer (b2 ) 35 g (0.0058 mol, SP value is 10.08) of one-end methacryloyl polymethyl methacrylate (trade name AA-6) used in Example 1, and 2-hydroxyethyl methacrylate as monomer (b3) (HEMA, manufactured by Wako Pure Chemical Industries, Ltd.) 12.5 g (0.096 mol, SP value is 13.47), 16.5 g of methyl ethyl ketone (MEK), 16.6 g of isopropanol (IPA) as a solvent, and a polymerization initiator 2,2′-azobis (2,4-dimethylvaleronitrile) (manufactured by Wako Pure Chemical Industries, Ltd., V -65) A solution (monomer concentration 60%) mixed with 1 g was prepared.
Thereafter, the same operation as in Example 1 was performed to obtain a copolymer of poly (2-hydroxyethyl methacrylate-g- (2-ethyloxazoline) -g-methyl methacrylate). The weight average molecular weight of this polymer (B-2) was 53,600.
The SP value of this polymer (B-2) was 10.91 as described below.
13.47 × (12.5 / 50) + 9.82 × (2.5 / 50) + 10.08 × (35/50) = 10.91
The results are shown in Table 1.

Production Example 3 [Production of polymer (B-3)]
Without using the nitrogen-containing macromonomer (b1), 32.5 g (0.0054 mol, SP) of the one-terminal methacryloyl polymethyl methacrylate (trade name AA-6) used in Example 1 was used as the macromonomer (b2). The value is 10.08), the monomer (b3) is 17.5 g (0.135 mol, SP value is 13.47) of HEMA, the solvent is MEK 16.5 g, IPA 16.5 g, and the polymerization initiator (V-65). A solution (monomer concentration 60%) mixed with 1 g was prepared.
Then, operation similar to Example 1 was performed and the copolymer polymer of poly (2-hydroxyethyl methacrylate-g-methyl methacrylate) was obtained. The weight average molecular weight of this polymer (B-3) was 34,900.
The SP value of this polymer (B-3) was 11.27 as a result of calculation in the same manner as described above. The results are shown in Table 1.

Example 1 [Preparation of Dispersion]
4 g of the copolymer (B-1) obtained in Production Example 1 was suspended in 86 g of propylene glycol monomethyl ether acetate (PGMEA, SP value 8.73, boiling point 145 ° C.), and this was put in a sealed polyethylene container at 70 ° C. Was sufficiently heated in an oven to obtain a transparent uniform solution. In this container, as pigment (C), diketopyrrolopyrrole pigment (Ciba Specialty Chemicals, Inc., CI Pigment Red 254, trade name “IRGAPHOR BT-CF”, average primary particle size 30 nm 10 g of (catalog value)) and 200 g of zirconia beads (0.3 mm in diameter) were added, and the mixture was crushed for 3 hours using a paint shaker. After crushing, zirconia beads were removed using a mesh to obtain a PGMEA dispersion of diketopyrrolopyrrole pigment. Table 2 shows the measurement results of viscosity, particle size, and adsorption rate.

Example 2 Preparation of Dispersion
The same operation as in Example 1 was performed using the copolymer (B-2) obtained in Production Example 2 to obtain a PGMEA dispersion of a diketopyrrolopyrrole pigment. Table 2 shows the measurement results of viscosity, particle size, and adsorption rate.

Example 3 [Preparation of Dispersion]
The same operation as in Example 1 was performed using the copolymer (B-3) obtained in Production Example 3 to obtain a PGMEA dispersion of a diketopyrrolopyrrole pigment. Table 2 shows the measurement results of viscosity, particle size, and adsorption rate.

Comparative Example 1
4 g of the copolymer (B-1) obtained in Production Example 1 was suspended in 86 g of propylene glycol monomethyl ether acetate (PGMEA). In the obtained solution, the copolymer was not uniformly dispersed in the organic solvent.
This suspension was put in a closed polyethylene container, 10 g of the diketopyrrolopyrrole pigment used in Example 1 and 200 g of zirconia beads (diameter 0.3 mm) were added, and the mixture was crushed with a paint shaker for 3 hours. After crushing, zirconia beads were removed using a mesh to obtain a PGMEA dispersion of diketopyrrolopyrrole pigment. Since the obtained dispersion gelated after storage for 5 days, the viscosity after 5 days and the storage stability could not be evaluated and measured in the same manner as in the Examples.
Comparative Example 2
4 g of the copolymer (B-1) obtained in Production Example 1 is mixed with 86 g of hexane (SP value: 7.28, boiling point: 67 ° C.). This was put into a sealed polyethylene container and sufficiently heated in an oven at 50 ° C. to obtain a solution. In the obtained solution, the copolymer was not uniformly dispersed in the organic solvent. In this container, 10 g of the diketopyrrolopyrrole pigment used in Example 1 and 200 g of zirconia beads (diameter 0.3 mm) were added, and pulverized for 3 hours with a paint shaker. After crushing, the zirconia beads were removed using a mesh, and an attempt was made to obtain a hexane dispersion of a diketopyrrolopyrrole pigment. I couldn't.

  In Table 2, it can be seen that the non-aqueous pigment dispersions obtained in Examples 1 to 3 are extremely excellent in dispersibility and storage stability.

  The non-aqueous pigment dispersion of the present invention is useful as a color material for color filters used in color liquid crystal displays and the like.

Claims (5)

The manufacturing method of the non-aqueous pigment dispersion including the following process 1 and process 2.
Step 1: Organic solvent (A) and SP value [solubility parameter (cal / cm ³ ) ^1/2 ] are [SP value of organic solvent (A) +1] to [SP value of organic solvent (A) +3]. Step of mixing a certain graft polymer (B) and obtaining a pre-dispersion by heat treatment Step 2: Step of adding the pigment (C) to the obtained pre-dispersion and dispersing to obtain a pigment dispersion   The manufacturing method of the non-aqueous pigment dispersion of Claim 1 which performs the heat processing of the process 1 at 40-150 degreeC. The manufacturing method of the non-aqueous pigment dispersion of Claim 1 or 2 whose SP value of an organic solvent (A) is 8-9 (cal / cm < ³ >) ^<1/2 >. The manufacturing method of the non-aqueous pigment dispersion in any one of Claims 1-3 whose SP value of graft polymer (B) is 10-12 (cal / cm < ³ >) ^<1/2 >.   A non-aqueous pigment dispersion obtained by the production method according to claim 1.