Dispersion for black partition wall materials

Abstract

To provide a dispersion for black partition materials that can increase the taper angle of black partition material, also decrease its reflectance, and allows for making a high-precision display.SOLUTION: A dispersion for black partition materials contains lactam black, an acrylic dispersant, a resin, and a solvent. The lactam black has a volume-based particle size (D50 value) of 20-60 nm and a volume-based particle size (D90 value) of 40-110 nm. The acrylic dispersant contains a block copolymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a dispersion liquid for a black partition wall material. More specifically, the present invention relates to a dispersion liquid for a black partition wall material that can increase the taper angle of the black partition wall material and reduce the reflectance, thereby enabling the production of a high-definition display. [Background technology]

[0002] Conventionally, black partition wall materials used in displays are required to have high electrical insulation to prevent malfunctions. Carbon black, which is used as a black colorant, is surface-coated with an insulating material to achieve high electrical insulation. If the coating is incomplete, electrical insulation is not achieved, and sufficient reliability is not obtained. Furthermore, flexible type displays do not use circular polarizers used for anti-reflection, and color filters are used for anti-reflection purposes. Black partition wall materials used in color filters are required to have lower reflectivity than conventional materials. Lactam black is a black colorant that has attracted attention for these applications (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-86157 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the resin composition having lactam black dispersed therein described in Patent Document 1 is used as a black partition wall material, a sufficient taper angle cannot be obtained, and the resin composition is not suitable for achieving high resolution displays.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and has an object to provide a dispersion liquid for a black partition wall material, which can increase the taper angle of a black partition wall material and can reduce the reflectance, thereby enabling the production of a high-definition display. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems, and have found that the above problems can be solved simultaneously by using a dispersant that combines finely divided lactam black with an acrylic dispersant that is a block copolymer, thereby completing the present invention. The present invention, which solves the above problems, mainly comprises the following features.

[0007] (1) A dispersion for a black partition wall material, comprising: lactam black; an acrylic dispersant; a resin; and a solvent; wherein the lactam black has a volume-based particle size D50 value of 20 to 60 nm and a volume-based particle size D90 value of 40 to 110 nm; and the acrylic dispersant contains a block copolymer.

[0008] According to this configuration, the taper angle of the obtained black partition wall material can be increased and the reflectance can be reduced, and a dispersion for a black partition wall material that can produce a high-definition display can be provided. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a dispersion for a black partition wall material, which can increase the taper angle of the black partition wall material and reduce the reflectance, thereby enabling the production of a high-definition display. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Dispersion liquid for black partition material> A dispersion for a black partition wall material (hereinafter also referred to as dispersion) according to one embodiment of the present invention contains lactam black, an acrylic dispersant, a resin, and a solvent. The lactam black has a volume-based particle size D50 value of 20 to 60 nm and a volume-based particle size D90 value of 40 to 110 nm. The acrylic dispersant contains a block copolymer. Each of these will be described below.

[0011] (Lactam Black) The lactam black is a known lactam black having the following structure: Specifically, the lactam black is Irgaphor Black S 0100 CF (manufactured by BASF) or the like.

[0012] [ka]

[0013] The lactam black of this embodiment is a lactam black obtained by micronizing a known lactam black. The micronization method is not particularly limited. For example, the micronization is a method in which a known lactam black is pretreated with a water-soluble inorganic salt and a wetting agent. Specifically, the pretreatment can be carried out by kneading the lactam black with the water-soluble inorganic salt and the wetting agent, and then filtering and washing the resulting pigment. The kneading can be carried out at a temperature of 40 to 100°C. The filtration and washing can be carried out by washing the inorganic salt with water or the like, followed by filtration. The water-soluble inorganic salt can be sodium chloride, potassium chloride, or the like.

[0014] The volumetric particle size D50 of the finely divided lactam black of this embodiment may be 20 nm or more, preferably 30 nm or more. The D50 may be 60 nm or less, preferably 50 nm or less. If the D50 value is less than 20 nm, the dispersion will have poor dispersion stability. On the other hand, if the D50 value exceeds 60 nm, the resulting black partition wall material will have a small taper angle and high reflectance.

[0015] The volume-based particle size D90 of the finely divided lactam black of this embodiment may be 40 nm or more, preferably 50 nm or more. The D90 may be 110 nm or less, preferably 100 nm or less. If the D90 value is less than 40 nm, the dispersion will have poor dispersion stability. On the other hand, if the D90 value exceeds 110 nm, the resulting black partition wall material will have a small taper angle and high reflectance.

[0016] The volume-based particle size D10 of the micronized lactam black of this embodiment is preferably 5 nm or more, more preferably 15 nm or more, and is preferably 40 nm or less, more preferably 30 nm or less.

[0017] In this embodiment, the volume-based particle size can be measured by a laser diffraction particle size measurement method using a Nanotrac (UPA-EX150, manufactured by Nikkiso Co., Ltd.).

[0018] The dispersion of this embodiment is characterized by the volume-based particle size, particularly D50 and D90, falling within a predetermined range. By ensuring that D50 and D90 fall within the above ranges, the resulting black partition wall material has a larger taper angle and lower reflectance. That is, the smaller the pigment particle size, the easier it is for light to transmit, resulting in less reflected light. Furthermore, a smaller pigment particle size makes it easier for UV light to diffract to the back side of the pigment, facilitating overall curing and reducing thermal flow. Furthermore, a smaller pigment particle size increases the surface area of ​​the pigment that interacts with the resin and dispersant. As a result, the coating film has stronger bonding strength within the coating film and is less susceptible to thermal flow.

[0019] The content of lactam black is not particularly limited. For example, the content of lactam black in the dispersion is preferably 5% by mass or more, more preferably 10% by mass or more. The content of lactam black in the dispersion is preferably 30% by mass or less, more preferably 25% by mass or less. When the content of lactam black is within the above range, the dispersion has good dispersion stability.

[0020] (acrylic dispersant) The acrylic dispersant includes a block copolymer (acrylic block copolymer). The acrylic block copolymer is not particularly limited. For example, the acrylic block copolymer is an acrylic block copolymer containing an amine compound as a monomer.

[0021] The types of blocks constituting the acrylic block copolymer containing a monomer that is an amine compound may be two or three or more, and one or more of the blocks are blocks containing a monomer that is an amine compound and has a radically polymerizable unsaturated bond.

[0022] The monomers constituting this block are acyclic amine compounds, heterocyclic amine compounds, or quaternary ammonium cation compounds, preferably acyclic amine compounds such as dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, and dimethylaminobutyl (meth)acrylate, heterocyclic amine compounds such as vinylpyridine and pentamethylpiperidinyl (meth)acrylate, and quaternary ammonium cation compounds such as compounds obtained by quaternizing and cationizing dimethylaminopropyl (meth)acrylate with benzyl chloride. The block may be composed of one of these monomers, or may be composed of a block formed by random polymerization of two or more monomers, or a block formed by block polymerization of two or more monomers. Furthermore, structures consisting of blocks of pentamethylpiperidinyl methacrylate and / or dimethylaminopropyl acrylate and blocks formed by other polymerizable ethylenically unsaturated monomers are particularly preferred.

[0023] The other polymerizable block copolymerized with the block derived from the amine compound monomer may be a block consisting of one type of monomer, or may be a block in which two or more types of monomers are randomly polymerized. It is preferable that the block does not contain a unit derived from a monomer containing an amino group or a pyridine ring. It is also more preferable that the block does not contain a carboxylic acid group, a hydroxyl group, a thiol group, or a sulfur- or phosphorus-containing group. The block consisting of the other polymerizable ethylenically unsaturated monomer may be one type or two types.

[0024] Other polymerizable ethylenically unsaturated monomers include copolymers with at least one ethylenically unsaturated monomer selected from the group consisting of alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, and butyl (meth)acrylate, styrene, 2-hydroxyethyl (meth)acrylate, allyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, and glycerol (meth)acrylates such as glycerol monoacrylate, N-phenylmaleimide, polystyrene macromonomer, polymethyl methacrylate macromonomer, and carboepoxy diacrylate. However, it is preferable not to use N-vinylpyrrolidone or sulfur-containing monomers.

[0025] The block copolymer may be a block resin synthesized by living radical polymerization or anionic polymerization.

[0026] The content of the acrylic dispersant is not particularly limited. For example, the content of the acrylic dispersant in the dispersion is preferably 0.5% by mass or more, and more preferably 1.0% by mass or more. The content of the acrylic dispersant in the dispersion is preferably 30.0% by mass or less, and more preferably 25.0% by mass or less. When the content of the acrylic dispersant is within the above range, the particle size distribution of the dispersion is easily adjusted to a particle size within a desired range, and the dispersion stability is improved.

[0027] (resin) The resin is not particularly limited. For example, the resin is preferably an alkali-soluble resin, and more preferably an acrylic copolymer resin, a maleic acid copolymer resin, a polyester resin obtained by a condensation polymerization reaction, a polyurethane resin, or the like. Among these, the resin is preferably an acrylic copolymer resin in terms of developability, flexibility in molecular design, and cost. By including an alkali-soluble resin, the dispersion liquid can be developed with an alkali developer, and a pattern such as a partition wall can be formed.

[0028] The alkali-soluble resin is not particularly limited. For example, the alkali-soluble resin is a resin containing an anionic group such as a carboxyl group, a sulfonic acid group, or a phosphonic acid group (-P(=O)(OH)).

[0029] From the viewpoint of alkali developability, the acid value of the alkali-soluble resin is preferably 10 mgKOH / g or more, more preferably 20 mgKOH / g or more, and is preferably 300 mgKOH / g or less, more preferably 200 mgKOH / g or less.

[0030] The weight-average molecular weight of the alkali-soluble resin is preferably 5,000 or more, more preferably 10,000 or more, from the viewpoint of resist film formability. Furthermore, the weight-average molecular weight of the alkali-soluble resin is preferably 100,000 or less, more preferably 50,000 or less, from the viewpoint of improving solubility. The weight-average molecular weight can be measured by gel permeation chromatography (GPC). For example, chromatography is performed using a Water 2690 (manufactured by Waters) GPC apparatus and a PLgel 5μ MIXED-D (manufactured by Polymer Laboratories) column under the following conditions: tetrahydrofuran as the developing solvent, a column temperature of 25°C, a flow rate of 1 milliliter / minute, an RI detector, a sample injection concentration of 10 milligrams / milliliter, and an injection volume of 100 microliters, and the weight-average molecular weight can be determined as polystyrene equivalent.

[0031] The alkali-soluble resin is an acrylic copolymer resin, a maleic acid copolymer resin, a polyester resin obtained by a condensation polymerization reaction, a polyurethane resin, etc. Among these, the alkali-soluble resin is preferably an acrylic copolymer resin from the viewpoints of developability, flexibility in molecular design, and cost.

[0032] The content of the alkali-soluble resin is not particularly limited. For example, the content of the alkali-soluble resin is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, relative to 100 parts by mass of lactam black. The content of the alkali-soluble resin is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, relative to 100 parts by mass of lactam black.

[0033] (solvent) The solvent is not particularly limited, but from the viewpoint of stably dispersing lactam black and sufficiently dissolving resins and the like, preferred examples of the solvent include ester-based solvents, ether-based solvents, ether ester-based solvents, ketone-based solvents, aromatic hydrocarbon-based solvents, and nitrogen-containing solvents.

[0034] Examples of ester solvents include methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, 3-methyl-3-methoxybutylpropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, ethyl ethoxyacetate, hydroxyacetic acid esters, and n-amyl formate.

[0035] Examples of the ether solvent include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dimethyl ether, and diethylene glycol methyl ethyl ether.

[0036] Examples of the ether ester solvent include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate.

[0037] The ketone solvents include methyl isobutyl ketone, cyclohexanone, 2-heptanone, and δ-butyrolactone.

[0038] The aromatic hydrocarbon solvents include toluene, xylene, and alkylnaphthalene.

[0039] The nitrogen-containing solvents include N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0040] The content of the solvent is not particularly limited. For example, the content of the solvent in the dispersion is preferably 40% by mass or more, more preferably 50% by mass or more. The content of the solvent in the dispersion is preferably 90% by mass or less, more preferably 80% by mass or less. When the content of the solvent is within the above range, the dispersion has excellent dispersion stability of lactam black.

[0041] Returning to the explanation of the dispersion as a whole, the method for preparing the dispersion of this embodiment is not particularly limited. For example, the dispersion can be prepared by mixing various materials and kneading them overnight using a bead mill or the like.

[0042] The dispersion of this embodiment can increase the taper angle of the black partition wall material and also reduce the reflectance, making it possible to manufacture a high-definition display.

[0043] <Black partition wall material> The black partition wall material is obtained by curing the above-described dispersion liquid. Specifically, first, the dispersion liquid of this embodiment is applied to a substrate to form a resin layer (coating film). Then, the resin layer is exposed to light through a mask with a predetermined pattern, and the exposed portions are photocured. Then, the unexposed portions and the partially exposed portions are developed with an alkaline developer to form the black partition wall material. Thereafter, the black partition wall material is post-baked as necessary.

[0044] The substrate is not particularly limited, and examples thereof include a glass substrate, a silicon substrate, a polycarbonate substrate, a polyester substrate, a polyamide substrate, a polyamideimide substrate, a polyimide substrate, an aluminum substrate, a printed wiring board, and an array substrate.

[0045] The method for applying the dispersion is not particularly limited. Examples of the dispersion application method include screen printing, roll coating, curtain coating, spray coating, and spin coating. After the dispersion is applied, the solvent contained in the resin layer may be evaporated, if necessary, by heating using a heating means such as a circulation oven, an infrared heater, or a hot plate. The heating conditions may be appropriately set depending on the composition of the dispersion used. Generally, the heating conditions are a temperature of 50°C to 120°C and a time of 30 seconds to 30 minutes.

[0046] The method of exposing the resin layer is not particularly limited. For example, the exposure method is irradiation with active energy rays such as ultraviolet rays and excimer laser light. The amount of energy radiation may be appropriately set depending on the composition of the dispersion liquid. For example, the energy dye may be irradiated with an amount of 30 to 2000 mJ / cm. 2 The light source used for exposure is not particularly limited. Examples of the light source include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a xenon lamp, and a metal halide lamp.

[0047] The alkaline developer used for development is not particularly limited. Examples of the developer include aqueous solutions of sodium carbonate, potassium carbonate, calcium carbonate, sodium hydroxide, potassium hydroxide, etc.; aqueous solutions of amine compounds such as ethylamine, diethylamine, and dimethylethanolamine; and aqueous solutions of p-phenylenediamine compounds such as tetramethylammonium, 3-methyl-4-amino-N,N-diethylaniline, 3-methyl-4-amino-N-ethyl-N-β-hydroxyethylaniline, 3-methyl-4-amino-N-ethyl-N-β-methanesulfonamidoethylaniline, and 3-methyl-4-amino-N-ethyl-N-β-methoxyethylaniline, and sulfates, hydrochlorides, or p-toluenesulfonates thereof. The alkaline developer may contain, as needed, an antifoaming agent, a surfactant, or the like.

[0048] The black partition wall material formed by alkali development can be post-baked to promote curing of the resin. The post-baking conditions are not particularly limited. For example, the post-baking conditions are a temperature of 80°C to 250°C and a time of 10 minutes to 4 hours.

[0049] The resulting black partition wall material has a large taper angle and low reflectance, making it possible to fabricate a high-definition display.

[0050] <Image display device> The image display device (display) of this embodiment includes the above-mentioned black partition wall material. Specific examples of the image display device include a liquid crystal display device, an organic EL display device, etc. The image display device can be manufactured according to a conventional method except for forming the above-mentioned black partition wall material. [Example]

[0051] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

[0052] The raw materials used are shown below. <Lactam Black> Lactam black: Irgaphor S100CF (BASF) Preparation of micronized lactam black 800 parts by mass of the lactam black, 8,000 parts by mass of sodium chloride having a particle size of 20 μm, and 1,920 parts by mass of diethylene glycol were placed in a Trimix TX-15 (manufactured by Inoue Seisakusho) tank. The mixture was kneaded for 3 hours at 45°C at 70% of the rated current of 9.3 A, followed by salt milling. 1,300 parts by mass of the resulting kneaded mixture was placed in 3 liters of warm water and stirred for 1 hour while heating to 70°C to form a slurry. After repeated filtration and water washing to remove the sodium chloride and diethylene glycol, the mixture was dried overnight at 40°C to obtain 95 parts by mass of finely divided lactam black. Preparation of finely divided lactam black (salt trimming reinforced product) The same preparation method as in the above-mentioned preparation of finely divided lactam black was used, except that 400 parts by mass of lactam black was kneaded for 6 hours, to obtain 40 parts by mass of finely divided lactam black (salt trimming-reinforced product). <Dispersant> Preparation of acrylic dispersant (ABA triblock) A degassed glass reactor was charged with 17 g of methyl methacrylate (MMA), 24 g of butyl methacrylate (BMA), and 1 L of tetrahydrofuran (THF). 4.5 mmol of a hexane solution of n-butyllithium was then added to synthesize the random copolymer of MMA and BMA. The mixture was then cooled to -78°C and stirred for 2 hours. Next, 33 g of pentamethylpiperidinyl methacrylate (PMPMA) was added and stirred for 2 hours to synthesize the PMPMA block moiety bonded to the random copolymer of MMA and BMA. Further, 17 g of MMA and 24 g of BMA were added to synthesize the ABA triblock copolymer. After stirring for 2 hours, the reaction was stopped. The completed solution was dropped into a large amount of methanol to precipitate the product. The dispersant was collected using filter paper, washed several times with methanol, and dried under reduced pressure at 60°C to obtain the acrylic dispersant. The resulting acrylic dispersant was an ABA triblock copolymer, BMA / MMA / / b-PMPMA / / b-BMA / MMA = (24 / 17) / / 18 / / (24 / 17). The monomers separated by " / " were polymerized randomly, while the monomers separated by " / / b-" formed a block structure. Acrylic dispersant (graft): BYKJET-9151 (BYK Chemie) Urethane dispersant (graft): DISPERBYK-167 (BYK) <Photopolymerizable compound> DPEHA: Dipentaerythritol hexaacrylate <Photopolymerization initiator> Irgacure OXE02 (BASF) <Solvent> PGME: Propylene glycol monomethyl ether PGMEA: Propylene glycol monomethyl ether acetate <Resin> Foret ZAH-110 (alkali-soluble photosensitive resin, solid content 35% by mass, manufactured by Soken Chemical & Engineering Co., Ltd.) ZCR-1569H (alkali-soluble photosensitive resin, solid content 70% by mass, manufactured by Nippon Kayaku Co., Ltd.) <Leveling agent> Megafac F-554 (DIC)

[0053] <Examples 1 to 4 and Comparative Examples 1 to 6> (Preparation of pigment dispersion for black partition wall material) Various materials were mixed to obtain the composition (unit: mass %) shown in Table 1, and milled overnight in a bead mill to prepare pigment dispersions for black partition wall materials of Examples 1 to 4 and Comparative Examples 1 to 6. The particle sizes of the dispersion compositions in the obtained dispersions were measured by a laser diffraction particle size measurement method using a Nanotrac (UPA-EX150, manufactured by Nikkiso Co., Ltd.) to determine the D10 particle size, D50 particle size, and D90 particle size. The results are shown in Table 1.

[0054] (Preparation of Pigment Dispersion Resist Composition for Black Partition Wall Material) The above dispersion liquid with a pigment concentration of 15% by mass was mixed to a uniform composition of 40.00 parts by mass, alkali-soluble photosensitive resin ZCR-1569H was mixed to a concentration of 10.60 parts by mass, DPEHA was mixed to a concentration of 3.00 parts by mass, Irgacure OXE02 was mixed to a concentration of 0.80 parts by mass, Megafac F-554 was mixed to a concentration of 0.05 parts by mass, and PGMEA was mixed to a concentration of 45.55 parts by mass using a high-speed stirrer. The mixture was then filtered through a filter with a pore size of 3 μm to obtain pigment dispersion resist compositions for black partition wall materials.

[0055] The viscosity stability, taper angle, and reflectance of the resulting resist composition were measured by the following methods. The results are shown in Table 1.

[0056] (viscosity stability) The pigment dispersion resist compositions for black partition wall materials of the above Examples and Comparative Examples were stored at 40° C. for one week, and the change in viscosity before and after storage was measured and evaluated according to the following evaluation criteria. ○: The viscosity change was 10% or less. △: The viscosity change was more than 10% and 20% or less. ×: The viscosity change exceeded 20%.

[0057] (Taper angle) The pigment dispersion resist compositions for black partition wall materials of the above Examples and Comparative Examples were applied to a glass substrate (Corning 1737) using a spin coater to a film thickness of 1 μm, and prebaked at 100° C. for 2 minutes. Thereafter, a high-pressure mercury lamp was used to apply a UV integrated light dose of 40 mJ / cm to the substrate with a gap of 20 μm between the photomask having a line pattern and the substrate. 2 The substrate was exposed to light at 2000 K. Development was carried out at 23°C in a 2.4% by mass aqueous solution of TMAH (tetramethylammonium hydroxide) using a shower at 0.07 MPa, followed by rinsing with shower water at 0.07 MPa. The substrate was then post-baked at 250°C for 30 minutes. The resulting substrate was divided in the pattern width direction using a glass cutter. The divided surfaces of the 6 μm pattern were observed using an electron microscope, and the taper angle was measured by image analysis. The results are shown in Table 1. The larger the taper angle, the better.

[0058] (reflectance) The same procedure as for the taper angle was carried out, but without any development after exposure, post-baking was carried out at 100°C for 30 minutes to obtain a coating film formed only in the solid area. The average reflectance (unit: %) of the coating surface of the obtained solid area at wavelengths of 360 to 740 nm was measured using a reflectometer (Photal MC-7300:SC, ​​manufactured by Otsuka Electronics Co., Ltd.). The results are shown in Table 1. The smaller the average reflectance value, the better.

[0059] [Table 1]

[0060] As shown in Table 1, the dispersion for black partition wall material of the present invention was prepared so that the viscosity change was small and the volume-based particle size (particularly the D50 value and D90 value) was within a predetermined range. This shows that when the dispersion for black partition wall material of the present invention is used for black partition wall material, it is possible to increase the taper angle and obtain a coating film with low reflectance, making it suitable as a display material.

Claims

[Claim 1] The ink contains lactam black, an acrylic dispersant, a resin, and a solvent, The lactam black is The volume-based particle size D10 value is 5 to 40 nm, The volume-based particle size D50 is 20 to 60 nm, The volume-based particle size D90 is 40 to 110 nm, The acrylic dispersant contains a block copolymer.

Images