White pigment dispersion and composition for forming white separators containing the same.

Abstract

The technical problem to be solved by the present invention is to provide a white pigment dispersion and a composition for forming a white separator wall capable of forming a separator wall of a display element with good reflectivity. The solution of the present invention is a white pigment dispersion containing a white inorganic pigment, a polymeric dispersant, a dispersing aid, and a solvent. The polymeric dispersant is an acid-value type polymeric dispersant having a carboxyl or phosphate group. The dispersing aid contains a compound having a phthalimide skeleton as an active ingredient. The phthalimide skeleton may have substituents directly linked to its carbon atoms. A group having a carboxyl group or a group having a nitrogen-containing six-membered ring quaternary ammonium cation is linked to the nitrogen atom in the phthalimide skeleton.

Description

Technical Field

[0001] The present invention relates to a white pigment dispersion and a composition for forming a white partition wall containing the white pigment dispersion. Background Technology

[0002] In display panels using display elements such as micro light-emitting diodes (LEDs) and organic electroluminescent (OLEDs), fine patterns are formed by partitions to suppress light mixing, and light-emitting portions are disposed between the partitions. Such partitions are, for example, formed from a resin composition. Furthermore, as a composition capable of constituting such a resin composition, a coloring composition with properties such as shielding and reflectivity has been proposed to suppress light mixing (Patent Document 1).

[0003] Patent Document 1 describes a negative photosensitive coloring composition comprising (A) a white pigment, (B) a siloxane resin, (C) a photopolymerization initiator, (D) a photopolymerizable compound, and (E) an organic solvent. The siloxane resin (B) comprises structural units derived from fluorinated alkoxysilane compounds and structural units derived from difunctional alkoxysilane compounds, and these units are contained in a specified amount. Furthermore, with this configuration, a thick cured film with high reflectivity, high resolution, and excellent heat resistance can be formed.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2019 / 176785 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, while the reflectivity can be improved to some extent by using, for example, the composition described in Patent Document 1, there is still room for improvement in order to meet the high image quality requirements of the market.

[0009] Furthermore, in order to mitigate the recent phenomenon of global warming, it is necessary to reduce the power consumption of display elements. However, it is generally known that in display elements like the one described above, when the reflectivity of the partition walls is low, it is necessary to increase the voltage to improve the color density of each area. As a result, in order to reduce power consumption, it is necessary to increase the reflectivity; however, even when using, for example, the composition described in Patent Document 1, there is still room for improvement in meeting the energy-saving requirements of recent years.

[0010] Therefore, the object of the present invention is to provide a white pigment dispersion and a composition for forming a white separator wall capable of forming a separator wall of a display element having good reflectivity.

[0011] Technical solutions for solving technical problems

[0012] The inventors of this invention conducted in-depth research to solve the aforementioned technical problems. As a result, they discovered that by combining specific polymeric dispersants and specific dispersing aids, the reflectivity of the partition walls of the display element can be improved, thus completing this invention. The key points of this invention are as follows.

[0013] [1] A white pigment dispersion comprising a white inorganic pigment, a polymeric dispersant, a dispersing aid, and a solvent, wherein the polymeric dispersant is an acid-value-type polymeric dispersant having a carboxyl group or a phosphate group, and the dispersing aid contains a compound having a phthalimide skeleton as an active ingredient, wherein the phthalimide skeleton may have substituents directly linked to the carbon atoms of the phthalimide skeleton, and the nitrogen atom in the phthalimide skeleton is linked to a group having a carboxyl group or a group having a nitrogen-containing six-membered ring quaternary ammonium cation.

[0014] [2] The white pigment dispersion as described in the preceding item [1], wherein the substituents directly linked to the carbon atoms of the phthalimide skeleton are independently hydrogen atoms, halogen atoms, alkyl groups or aromatic hydrocarbon groups.

[0015] [3] The white pigment dispersion as described in [1] or [2] above, wherein the group having a carboxyl group is a saturated hydrocarbon group having a carboxyl group or an oxygen-containing five-membered ring residue having a carboxyl group.

[0016] [4] The white pigment dispersion as described in any one of the preceding items [1] to [3], wherein the compound having a phthalimide skeleton and having a carboxyl group attached to the nitrogen atom is selected from at least one of the compounds shown in the following formula (1).

[0017]

[0018] (In equation (1), R) 1 ~R 4 Independently representing a hydrogen atom, halogen atom, alkyl or aromatic hydrocarbon group, X represents a divalent saturated hydrocarbon group that may have substituents or a group shown in formula (2) below. In formula (2), "*" represents a valence bond.

[0019]

[0020] [5] The white pigment dispersion as described in any one of the preceding items [1] to [3], wherein the compound having a phthalimide skeleton and having a group having a nitrogen-containing six-membered ring quaternary ammonium cation attached thereto is at least one of the compounds shown in the following formula (3).

[0021]

[0022] (In equation (3), R) 1 ~R 4 Independently representing a hydrogen atom, halogen atom, alkyl group, or aromatic hydrocarbon group; A represents a group having a nitrogen-containing six-membered ring quaternary ammonium cation.

[0023] [6] A composition for forming a white partition wall, comprising the white pigment dispersion described in any one of the preceding items [1] to [5], and the component for forming a white partition wall.

[0024] The effects of the invention

[0025] According to the present invention, a white pigment dispersion capable of forming a partition wall of a display element having good reflectivity and a composition for forming a white partition wall are provided. Attached Figure Description

[0026] Figure 1 (a) is a photograph of Example 1; (b) is a photograph of Comparative Example 3.

[0027] Symbol Explanation

[0028] 1: The surface of the cured film; 2: The cross-section of the cured film; 3: The cross-section of the glass plate. Detailed Implementation

[0029] The white pigment dispersion of embodiments of the present invention comprises a white inorganic pigment, a polymeric dispersant, a dispersing aid, and a solvent. The aforementioned polymeric dispersant is an acid-value type polymeric dispersant having a carboxyl group or a phosphate group. The aforementioned dispersing aid contains a compound having a phthalimide skeleton as an active ingredient. Furthermore, the phthalimide skeleton may have substituents directly linked to the carbon atoms of the phthalimide skeleton, and the nitrogen atom in the phthalimide skeleton may be linked to a group having a carboxyl group or a group having a nitrogen-containing six-membered ring quaternary ammonium cation.

[0030] It can be considered that this white pigment dispersion, by containing the aforementioned specific acid-value type polymeric dispersant and specific dispersing aids, not only exhibits good dispersion within the dispersion itself but also maintains good dispersion within the coating film or separator. It can be considered that by achieving good dispersion within the coating film, the coating surface becomes smoother, enabling greater light reflection. Furthermore, even for light transmitted through the surface of titanium dioxide, the reflectivity is improved through reflection by the uniformly present titanium dioxide within the coating film. As a result, it can be considered that the reflectivity of the separator obtained using this method can be improved.

[0031] As for the aforementioned white inorganic pigments, there are no particular limitations as long as they can block or reflect light radiated from the luminescent part. Examples include aluminum oxide, magnesium oxide, antimony oxide, titanium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, magnesium carbonate, barium carbonate, calcium carbonate, lead sulfate, lead phosphate, zinc phosphate, silicon dioxide, zinc oxide, tin oxide, strontium sulfide, strontium titanate, barium titanate, barium tungstate, calcium silicate, aluminum silicate, lead metasilicate, talc, mica, kaolin, clay, bismuth oxychloride, and hollow silica particles. Among these, aluminum oxide, magnesium oxide, antimony oxide, titanium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, barium sulfate, magnesium carbonate, and barium carbonate are preferred, with titanium oxide being particularly preferred. These white inorganic pigments can contain one or more of these types. Titanium oxide can be either anatase or rutile, with rutile being preferred.

[0032] White inorganic pigments can be surface-treated. Examples of such surface treatments include treatments that cover the surface with inorganic compounds such as (aqueous) alumina, silica (high-density silica, porous silica), zirconium oxide, fatty acids, organosilicones, polyols, amines, and combinations thereof.

[0033] From the viewpoint of reflectivity and tinting strength, the preferred size of white inorganic pigments is an average primary particle size of 100–400 nm. The average primary particle size can be measured, for example, using a transmission electron microscope (JEM-1011) manufactured by Nippon Electron Ltd.

[0034] The preferred content of white inorganic pigment in the white pigment dispersion is 50-80% by weight.

[0035] Polymer dispersants can be acid-value-type polymeric dispersants that have carboxyl or phosphate groups (hereinafter sometimes referred to as "acidic groups"). Examples include polymeric dispersants containing polymers with carboxyl or phosphate groups in their side chains as active ingredients. The composition of the polymer backbone is not particularly limited, but it is preferable to have structural units derived from monomers containing carbon-carbon double bonds. Furthermore, when using multiple monomers, from the viewpoint of adjusting the acid value, it is preferable to use a combination of monomers with acidic groups and monomers without acidic groups. Such polymers are preferably copolymers. Copolymers can be random copolymers, alternating copolymers, block copolymers, or other types of copolymers. The structure of block copolymers is not particularly limited; examples include AB-type block copolymers formed by combining an A-block from monomer A and a B-block from a different monomer B; BAB-type block copolymers with a B-block-A-block-B-block structure; and ABC-type block copolymers with an A-block-B-block-C-block structure formed by combining a C-block from a monomer C different from monomers A and B. Furthermore, from the viewpoint of dispersibility and developability, it is preferable that the block copolymer contains blocks with acidic groups and blocks without acidic groups. Additionally, each block can be composed of structural units from a single monomer or structural units from multiple monomers. When a block is composed of structural units from multiple monomers, each structural unit can be contained within the block in any manner, such as random copolymerization or block copolymerization.

[0036] Examples of monomers with carbon-carbon double bonds include vinyl monomers with carboxyl or phosphate groups, and vinyl monomers without acidic groups.

[0037] Examples of vinyl monomers with acidic groups include monomers obtained by reacting anhydrides such as (meth)acrylic acid, butenoic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, succinic anhydride, and phthalic anhydride with hydroxyalkyl esters of (meth)acrylic acid such as (meth)acrylic acid-2-hydroxyethyl ester or (meth)acrylic acid-4-hydroxybutyl ester; vinyl monomers with carboxyl groups such as vinylbenzoic acid; vinyl monomers with sulfonic acid groups such as styrene sulfonic acid, dimethylpropyl sulfonate (meth)acrylamide, ethyl sulfonate (meth)acrylamide, ethyl sulfonate (meth)acrylamide, and vinyl sulfonic acid; and vinyl monomers with phosphate groups such as methacryloyloxyethyl phosphate.

[0038] Examples of vinyl monomers that do not possess acidic groups include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, n-hexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, n-dodecyl methacrylate, n-stearyl methacrylate, and other alkyl methacrylates; cyclohexyl methacrylate, methylcyclohexyl methacrylate, cyclododecyl methacrylate, borneol methacrylate, isoborneol methacrylate, dicyclopentyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyl methacrylate, and other alkyl methacrylates; and cyclohexyl methacrylate, methylcyclohexyl methacrylate, cyclododecyl methacrylate, borneol methacrylate, isoborneol methacrylate, dicyclopentyl methacrylate, dicyclopentenyl methacrylate, and other alkyl methacrylates. Acrylic cycloalkyl esters of acrylate; aryl esters of methacrylate such as benzyl methacrylate, phenyl methacrylate, and phenoxyethyl methacrylate; hydroxyl-containing methacrylates such as 2-hydroxyethyl methacrylate, 3-hydroxypropyl methacrylate, 2-hydroxypropyl methacrylate, and 4-hydroxybutyl methacrylate; methacrylates with polyethylene glycol structural units such as diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, polyethylene glycol mono(meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxytriethylene glycol (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, and methoxypolyethylene glycol (meth)acrylate; aromatic vinyl monomers such as styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methoxystyrene, 2-hydroxymethylstyrene, and 1-vinylnaphthalene.

[0039] From the viewpoint of dispersion stability, the polymeric dispersant, in other words, the polymer contained as an active ingredient, preferably has an acid value greater than 0 mg KOH / g and less than 200 mg KOH / g. It may have an amine value within a range not exceeding the acid value, and more preferably, it does not have an amine value. Furthermore, the weight-average molecular weight of the polymer is preferably between 3000 and 30000.

[0040] As described above, polymeric dispersants containing polymers with carboxyl or phosphate groups on their side chains as active ingredients can be, for example, polymeric dispersants disclosed in Japanese Patent No. 6437628. Alternatively, commercially available polymeric dispersants can also be used. Examples of commercially available dispersants include: TERPLUS MD1000, D2011, and MD1100 manufactured by Otsuka Chemicals Co., Ltd.; JDX-C3000A manufactured by BASF Corporation; DISPERBYK-111 manufactured by BYK-Chemie Corporation; S36000 manufactured by Lubrizol Corporation; and FLOWLEN G-700 manufactured by Kyoei Chemicals Co., Ltd.

[0041] The content of the polymeric dispersant relative to 100 parts by weight of the white inorganic pigment is preferably 1 to 20 parts by weight, more preferably 1 to 10 parts by weight.

[0042] As described above, any acid-value polymeric dispersant containing carboxyl or phosphate groups is acceptable. From the viewpoint of forming a separator wall for a display element with better reflectivity, a carboxyl group is preferred.

[0043] The dispersing agent can have any of the specific structures described above. From the viewpoint of forming a partition wall for a display element with better reflectivity, it is preferable that the compound having the phthalimide skeleton is at least one of the compounds shown in formula (1) or (3) below.

[0044]

[0045] (In equation (1), R) 1 ~R 4 Independently representing a hydrogen atom, halogen atom, alkyl or aromatic hydrocarbon group, X represents a divalent saturated hydrocarbon group that may have substituents or a group shown in formula (2) below. In formula (2), "*" represents a valence bond.

[0046]

[0047] (In equation (3), R) 1 ~R 4 Independently representing a hydrogen atom, halogen atom, alkyl group, or aromatic hydrocarbon group; A represents a group having a nitrogen-containing six-membered ring quaternary ammonium cation.

[0048] In equations (1) and (3), R 1 ~R 4 When independently alkyl, although not particularly limited, from the viewpoint of dispersion stability, alkyl groups with 1 to 6 carbon atoms are preferred. Furthermore, alkyl groups may or may not have substituents. Examples of substituents include hydroxyl, carboxyl, alkoxy, carboxylic acid ester, amino, and amide groups. In R1 ~R 4 When the aromatic hydrocarbon group is independent, although there are no particular limitations, from the viewpoint of dispersion stability, an aromatic hydrocarbon group with 6 to 12 carbon atoms is preferred. The aromatic hydrocarbon group may or may not have substituents. When it has substituents, examples include hydroxyl, carboxyl, alkoxy, carboxylic acid ester, amino, and amide groups.

[0049] As compounds represented by formulas (1) and (3), R 1 ~R 4 The atom is preferably a hydrogen atom or a halogen atom. There is no particular limitation on the halogen atom, but a chlorine atom is particularly preferred.

[0050] When X in formula (1) is a divalent saturated hydrocarbon group that can have substituents, preferably a saturated hydrocarbon group with 1 to 10 carbon atoms, more preferably a saturated hydrocarbon group with 1 to 4 carbon atoms. Such a saturated hydrocarbon group can be linear or branched, preferably linear. When it has substituents, examples include alkoxy groups, carboxylic acid ester groups, amino groups, amide groups, etc.

[0051] When X in formula (1) is a group represented by formula (2) that can have substituents, examples of substituents include alkoxy, carboxylic acid ester, amino, and amide groups. Preferably, the group represented by formula (2) does not have substituents.

[0052] As the nitrogen-containing six-membered ring quaternary ammonium cation contained in the group represented by A in formula (3), any one of the group of cations described in formula (4) below can be listed, for example. In formula (4), "*" represents a valence bond.

[0053]

[0054] Examples of dispersants as described above are shown in formulas (5) to (7) below. Wherein, formula (5) is N-propionyl phthalimide, formula (6) is 3,4,5,6-tetrachlorophthalimide propionic acid, and formula (7) is 1-(4-(4-phenylphthalimide)phenyl)pyridinium sulfonic acid.

[0055]

[0056] The content of the dispersing agent is preferably 1 to 10 parts by weight relative to 100 parts by weight of the white inorganic pigment.

[0057] Dispersing agents can be synthesized using conventional methods or commercially available dispersing agents can be used.

[0058] The solvent can be a variety of organic solvents. Examples include ethanol, isopropanol, 1-propanol, 1-butanol, 2-butanol, isoamyl alcohol, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, methoxymethyl acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monopropyl ether, ethylene glycol monomethyl ether acetate, 1-methoxypropyl-2-acetate, acetone alcohol, acetylacetone, methyl isobutyl ketone, methyl ethyl ketone, methyl acetone, methyl lactate, toluene, cyclopentanone, cyclohexane, n-heptane, benzene, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, isoamyl acetate, amyl acetate, 3-hydroxy-3-methyl-2-butanone, and 4-hydroxy-3-methyl-2-butanone. 5-Hydroxy-2-pentanone, ethylene glycol diethyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-tert-butyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-tert-butyl ether, 2-ethoxyethyl acetate, 3-methoxy-1-butanol, 3-methoxy-3-methylbutanol, 3-methoxy-3-methylbutyl acetate, 3-methoxybutyl acetate, ethyl 3-ethoxypropionate, propylene glycol monomethyl ether propionate, dipropylene glycol methyl ether, diisobutyl ketone, diacetone alcohol, ethyl lactate, butyl lactate, dimethylformamide, dimethylacetamide, γ-butyrolactone, γ-valerolactone, δ-valerolactone, propylene carbonate, N-methylpyrrolidone, cyclohexanone, cycloheptanone, diethylene glycol monobutyl ether, ethylene glycol dibutyl ether, etc. These organic solvents can be used alone or in combination of two or more.

[0059] The content of organic solvent is not particularly limited; for example, it can be set to make the solid content in the white pigment dispersion reach 51 to 85% by weight.

[0060] In addition to the components mentioned above, white pigment dispersions may contain any additives as needed. Examples of such additives include dispersing resins, antioxidants, ultraviolet absorbers, sedimentation inhibitors, and adhesion promoters. Examples of adhesion promoters include substances described later.

[0061] White pigment dispersions can be prepared using conventional methods. For example, they can be obtained by adding the aforementioned components to known dispersers such as bead mills, sand mills, and dispersers. There are no particular limitations on the method of adding each component; the material can be dispersed by mixing all components simultaneously, or they can be added sequentially and dispersed accordingly. When using dispersion media such as zirconia beads, dispersion can be performed using a dispersion medium with a specified bead diameter, or the bead diameter can be reduced in stages over multiple stages. The bead diameter, temperature, time, and other conditions can be appropriately determined.

[0062] The composition for forming the white partition wall in the embodiment contains the aforementioned white pigment dispersion and white partition wall forming component. Because it contains the aforementioned white pigment dispersion, it is possible to form a partition wall for a display element with good reflectivity.

[0063] The white separating wall can be formed by components such as polymers, polymers, and mixtures thereof.

[0064] Examples of polymers include thermoplastic polyurethane resins, (meth)acrylic resins, polyamide resins, polyimide resins, styrene-maleic acid resins, polyester resins, silicone resins, cardo resins, and epoxy resins.

[0065] Regarding the content of the polymer in the composition for forming white separator walls, it is preferably 20 to 60% by weight of the total solid components of the composition for forming white separator walls.

[0066] As the polymerizable component, components usable in the art can be used, for example, at least one selected from compounds that are addition polymerizable compounds having at least one olefinic unsaturated double bond and having at least one, preferably two or more, terminal olefinic unsaturated bonds. Examples of such addition polymerizable compounds include monofunctional or polyfunctional acrylates. Regarding the content of the polymerizable component in the white separator wall forming composition, it is preferably 20 to 60% by weight of the total solids content of the white separator wall forming composition. Furthermore, when using such an addition polymerizable compound and a photopolymerization initiator, the polymerizable component includes the photopolymerization initiator.

[0067] In the composition for forming white partition walls, various additives such as antioxidants, ultraviolet absorbers, sensitizers (sensitizing pigments), chain transfer agents, fluorinated organic compounds, photopolymerization initiators, photopolymerization inhibitors, fillers, surfactants, adhesion promoters, agglomeration inhibitors, and surface conditioners (leveling agents) can be added as needed.

[0068] Among these additives, adhesion promoters can be used from the viewpoint of improving the adhesion between the composition for forming the white separator wall during development and the substrate (glass plate). As adhesion promoters, substances commonly used in this technical field can be applied. Examples include silane compound-based adhesion promoters such as silane coupling agents, and polymer-based adhesion promoters. Among these, polymer-based adhesion promoters tend to be effective. Commercially available polymer-based adhesion promoters can be used. Examples of products that can be listed include BYK-4509, BYK-4510, and BYK-4512 manufactured by BYK-Chemie Japan Co., Ltd.; DISPARLON APA-100 manufactured by Kusunoki Chemical Co., Ltd.; and TEGO AddBond LTW, TEGO AddBond LTW-B, TEGO AddBond LTH, TEGO AddBond HS, TEGO AddBond 1270, TEGO AddBond 2440, and TEGO AddBond 2220ND manufactured by Evonik JAPAN Co., Ltd., but these are not limited to. There is no particular limitation on the timing of adding the adhesion promoter. It can be added in full to the aforementioned white pigment dispersion beforehand to prepare a white separator wall forming composition, or it can be added in full when preparing the white separator wall forming composition, or it can be added in appropriate portions to both the white pigment dispersion and the white separator wall forming composition. Furthermore, the content of the adhesion promoter in the composition for forming white partition walls can be appropriately determined depending on the type of adhesion promoter, etc. Generally speaking, there is a tendency for a small amount to be sufficient.

[0069] The composition for forming white partition walls can be obtained, for example, by dispersing the above-mentioned components in a known disperser such as a bead mill, sand mill, or disperser.

[0070] The white partition wall forming composition described above can form a cured material with good reflectivity, and is therefore suitable for partition walls of display elements such as micro light-emitting diode (LED) elements and organic electroluminescent (organic EL) elements.

[0071] Example

[0072] The embodiments of the present invention will be described in detail below based on examples.

[0073] The following shows the white inorganic pigment, polymeric dispersant, dispersing aid, solvent, white coating film forming component, and white separator forming component used in Examples 1-3 and Comparative Examples 1-3 described below.

[0074] (1) White inorganic pigment (1-1) CR-60

[0075] Made by Ishihara Sangyo Co., Ltd., TIPAQUE CR-60, rutile titanium dioxide (TiO2), average primary particle size: 0.21 μm, surface treatment: alumina.

[0076] (2) Polymer dispersant (2-1) MD1100

[0077] Otsuka Chemicals Co., Ltd., TERPLUS MD1100, is an acid-value-type polymeric dispersant containing a carboxyl-containing BAB triblock copolymer as the active ingredient. Acid value: 85 mg KOH / g, amine value: 0 mg KOH / g, weight-average molecular weight: 25700, solid content: 40 wt%.

[0078] (2-2)C3000A

[0079] BASF JDX-C3000A is an acid-value-type polymeric dispersant containing an acrylic polymer compound with carboxyl groups as the active ingredient. Acid value: 85 mg KOH / g, amine value: 0 mg KOH / g, weight-average molecular weight: 10000, solid content: 100% by weight.

[0080] (3) Dispersing aids (3-1) Dispersing aid I

[0081] Contains the compound (N-propionyl phthalimide) of formula (5) obtained by conventional methods as the active ingredient, solid content: 100% by weight.

[0082] (3-2) Dispersant II

[0083] Contains the compound (3,4,5,6-tetrachlorophthalimide propionic acid) of formula (6) obtained by conventional methods as the active ingredient, solid content: 100% by weight.

[0084] (3-3) Dispersant III

[0085] Contains the compound (1-(4-(4-phenylphthalimide)phenyl)pyridinium sulfonic acid) of formula (7) obtained by conventional methods as the active ingredient, solid content: 100% by weight.

[0086] (3-4) Dispersant IV

[0087] Contains the compound (2-({4,6-bis[(5-carbamoyl-2-methoxyphenol)amino]-1,3,5-triazine-2-yl}amino)benzenesulfonic acid) as the active ingredient, obtained by conventional methods, as shown in formula (8), solid content: 100% by weight.

[0088]

[0089] (3-5) Dispersing agent V

[0090] Contains the compound (N-(1-aminoethyl)phthalimide) of formula (9) obtained by conventional methods as the active ingredient, solid content: 100% by weight.

[0091]

[0092] (3-6) Dispersing aid VI

[0093] Contains the compound (4-(3-(dimethylamino)propoxy)butyraldehyde) of formula (10) obtained by conventional methods as the active ingredient, solid content: 100% by weight.

[0094]

[0095] (4) Solvent (4-1) Propylene glycol monomethyl ether acetate (PMA), manufactured by Kyowa Hakko Chemical Co., Ltd.

[0096] (5) White coating forming component (5-1) RD-Y-206

[0097] Alkali-soluble resin, ACRYCURE (registered trademark) RD-Y-206, manufactured by Nippon Shokubai Co., Ltd. ((meth)acrylic acid polymer, solid content: 40% by weight).

[0098] (6) DPHA, a component for forming white separators

[0099] Dipentaerythritol hexaacrylate, manufactured by Nippon Kayaku Co., Ltd.

[0100] (6-2)184

[0101] Made by BASF, photopolymerization initiator Omnirad (registered trademark) 184.

[0102] (Example 1)

[0103] <Preparation of White Pigment Dispersions>

[0104] Relative to 63.05 parts by weight (solids) of white inorganic pigment (CR-60), 5.2 parts by weight (solids) of polymeric dispersant (MD1100), and 1.95 parts by weight (solids) of dispersing aid I, solvent (PMA) was added to bring the total concentration of the white inorganic pigment and dispersing aid I to 65% by weight. 400 parts by weight of zirconia beads with a particle size of 0.5 mm were added to 100 parts by weight of the white pigment dispersion, and dispersion was performed for 30 minutes using a paint conditioner. The resulting white pigment dispersion had a solids concentration of 70.2% by weight.

[0105] <Preparation of white coating film forming composition>

[0106] A white film-forming component (RD-Y-206) was added to the obtained white pigment dispersion so that the total ratio (solid content) of the white inorganic pigment and dispersant I during the formation of the cured film reached 60% by weight. PMA was added so that the solid content of the white film-forming composition reached 46% by weight. The mixture was stirred using a vortex mixer to obtain the white film-forming composition.

[0107] (Example 2)

[0108] Except for replacing dispersing aid I with dispersing aid II, the procedure was the same as in Example 1 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 70.2% by weight.

[0109] (Example 3)

[0110] Except for replacing dispersing aid I with dispersing aid III, the procedure was the same as in Example 1 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 70.2% by weight.

[0111] (Example 4)

[0112] <Preparation of White Pigment Dispersions>

[0113] Relative to 67.9 parts by weight (solid component) of white inorganic pigment (CR-60), 5.6 parts by weight (solid component) of polymeric dispersant (C3000A), and 2.1 parts by weight (solid component) of dispersant I, solvent (PMA) was added to bring the total concentration of the white inorganic pigment and dispersant I to 70% by weight. Otherwise, the procedure was the same as in Example 1 to obtain a white pigment dispersion. The resulting white pigment dispersion had a solid component concentration of 75.6% by weight.

[0114] <Preparation of white coating film forming composition>

[0115] Using the obtained white pigment dispersion, the same procedure as in Example 1 was followed to obtain a white coating film forming composition.

[0116] (Example 5)

[0117] Except for replacing dispersing aid I with dispersing aid II, the procedure was the same as in Example 4 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 75.6% by weight.

[0118] (Example 6)

[0119] Except for replacing dispersing aid I with dispersing aid III, the procedure was the same as in Example 4 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 75.6% by weight.

[0120] (Comparative Example 1)

[0121] Except for replacing dispersing aid I with dispersing aid IV, the procedure was the same as in Example 1 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 70.2% by weight.

[0122] (Comparative Example 2)

[0123] Except for replacing dispersing aid I with dispersing aid V, the procedure was the same as in Example 1 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 70.2% by weight.

[0124] (Comparative Example 3)

[0125] Except for replacing dispersing aid I with dispersing aid VI, the procedure was the same as in Example 1 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 70.2% by weight.

[0126] (Comparative Example 4)

[0127] Except for replacing dispersing aid I with dispersing aid IV, the procedure was the same as in Example 4 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 75.6% by weight.

[0128] (Comparative Example 5)

[0129] Except for replacing dispersing aid I with dispersing aid V, the procedure was the same as in Example 4 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 75.6% by weight.

[0130] (Comparative Example 6)

[0131] Except for replacing dispersing aid I with dispersing aid VI, the procedure was the same as in Example 4 to obtain a white pigment dispersion and a white coating film forming composition. The solid content concentration of the white pigment dispersion was 75.6% by weight.

[0132] (evaluate)

[0133] <Formation of Cured Film>

[0134] Using a spin coater (MIKASA Corporation, Opticoat MS-A150), the white coating film forming compositions obtained in Examples 1-6 and Comparative Examples 1-6 were coated onto glass plates with a thickness of 1 mm and a square dimension of 100 mm to prepare coated films. During this process, the spin speed was adjusted to achieve a film thickness of approximately 10 μm for each white coating film forming composition. After drying at room temperature for 3 minutes, the films were pre-baked at 90°C for 2.5 minutes, followed by post-baking at 230°C for 30 minutes, resulting in three cured films with different thicknesses.

[0135] <Measurement of Reflectivity>

[0136] For the obtained cured film, the number of visually identifiable particles was first measured. Reflectance was measured for cured films with fewer than 20 particles in a 5cm square shape. Cured films with more than 20 observed particles were not practically suitable for use and were marked as foreign matter in the reflectance measurement items in Table 1.

[0137] Next, the reflectance of each cured film was measured using a spectrophotometer (Konica Minolta, CM-3700A). A D65 light source was selected, and the Y value was measured using SCI method, calculating the average value for n=3. For each cured film obtained using the white coating film forming composition, the reflectance relative to the film thickness was plotted to obtain a calibration curve, from which the reflectance at a film thickness of 10 μm was determined.

[0138] <Cross-sectional observation of the cured film>

[0139] For the cured film formed on the surface of a glass plate using the white coating film forming composition obtained in Example 1 and Comparative Example 3, an oblique view of the cross section including the glass plate and the cured film in the stacking direction was obtained by scanning electron microscope (Hitachi High-Tech Co., Ltd., S-4800), and the cross section structure was observed visually. Figure 1 (a) is a photograph of Example 1, and (b) is a photograph of Comparative Example 3. Figure 1In the images (a) and (b) showing the oblique viewing direction, symbol 1 is the surface of the cured film formed on the glass plate, symbol 2 is the cross-section of the cured film, and symbol 3 represents the cross-section of the glass plate.

[0140] Table 1 shows the calculated composition and reflectance of the cured films of Examples 1-6 and Comparative Examples 1-6.

[0141] Table 1

[0142]

[0143] As shown in Table 1, it can be seen that by using the specified polymeric dispersant and the specified dispersing aid in combination, the reflectance is better compared to the comparative example without this combination. Furthermore, Figure 1 In the cured film of Example 1 (a), the surface ( Figure 1 Symbol 1 in (a) is in a smooth and even state, and the cross-section of the cured film ( Figure 1 In (a), the titanium oxide of symbol 2) diffuses in a dispersed state throughout the cured film, in contrast, Figure 1 In the cured film of Comparative Example 3 (b), the surface ( Figure 1 In (b), symbol 1) represents a concave-convex state, on the cross-section of the cured film ( Figure 1 In symbol 2) of (b), it is also confirmed that the difference between the dense and sparse parts caused by the aggregation of titanium oxide is quite large.

[0144] (Example 7)

[0145] <Preparation of the composition for forming white partition walls>

[0146] For the white pigment dispersion obtained in Example 1, 27.2% by weight of DPHA and 8.0% by weight of Omnirad (registered trademark) 184 were added as white separator wall forming components, such that the total ratio (solid content) of the white inorganic pigment and dispersant I when forming the cured film reached 60% by weight. PMA was added so that the solid content of the white separator wall forming composition reached 70% by weight. The mixture was stirred using a vortex mixer to obtain the white separator wall forming composition.

[0147] (evaluate)

[0148] <Formation of Cured Film>

[0149] The white separator-forming composition obtained in Example 7 was coated onto a 100mm square glass plate with a thickness of 1mm using a spin coater (MIKASA Co., Ltd., Opticoat MS-A150) to prepare a coated film. The spin speed was adjusted to achieve a film thickness of approximately 10μm. After drying at room temperature for 2.5 minutes, it was pre-baked at 90°C for 3 minutes. Next, an exposure apparatus (USHIO Electric Co., Ltd., UVC-02516S1LP01) was used to achieve 900mJ / cm². 2 The coated film was irradiated with ultraviolet light by means of light exposure intensity and heated at 230°C for 30 minutes (after baking) to obtain three cured films with different thicknesses.

[0150] <Measurement of Reflectivity>

[0151] The same procedure was followed as for the cured film of the white coating film forming composition, and the reflectance was calculated for the cured film of the white partition wall forming composition obtained in Example 7. The calculated results of the component composition and reflectance of the cured film of Example 7 are shown in Table 2.

[0152] Table 2

[0153]

[0154] *: Unit is parts by weight (based on solid content)

[0155] As shown in Table 2, even when a white separator forming component is used to form a cured film, it exhibits better reflectivity than the comparative examples, similar to the cases in Examples 1 to 6.

Claims

1. A white pigment dispersion, characterized in that: It contains white inorganic pigments, polymeric dispersants, dispersing aids, and solvents. The polymeric dispersant described herein contains only acid-value-type polymeric dispersants with carboxyl or phosphate groups, wherein the amine value of the acid-value-type polymeric dispersant is 0 mg KOH / g. The dispersing agent contains a compound with a phthalimide skeleton as an active ingredient. The phthalimide skeleton may or may not have substituents directly linked to the carbon atoms of the phthalimide skeleton. The nitrogen atom in the phthalimide skeleton is attached to a group with a carboxyl group or a group with a nitrogen-containing six-membered ring quaternary ammonium cation.

2. The white pigment dispersion as described in claim 1, characterized in that: The substituents directly linked to the carbon atoms of the phthalimide skeleton are independently hydrogen atoms, halogen atoms, alkyl groups, or aromatic hydrocarbon groups.

3. The white pigment dispersion as described in claim 1 or 2, characterized in that: The group having a carboxyl group is a saturated hydrocarbon group having a carboxyl group, or an oxygen-containing five-membered ring residue having a carboxyl group.

4. The white pigment dispersion as described in claim 1 or 2, characterized in that: The compound having a phthalimide skeleton and having a carboxyl group attached to the nitrogen atom is selected from at least one of the compounds shown in formula (1) below. In equation (1), R 1 ~R 4 Independently representing a hydrogen atom, halogen atom, alkyl or aromatic hydrocarbon group, X represents a divalent saturated hydrocarbon group with or without substituents or a group represented by formula (2) below, where "*" in formula (2) represents a valence bond.

5. The white pigment dispersion as described in claim 1 or 2, characterized in that: The compound having a phthalimide skeleton and having a group containing a nitrogen-containing six-membered ring quaternary ammonium cation attached to the nitrogen atom is selected from at least one of the compounds shown in formula (3) below. In equation (3), R 1 ~R 4 Independently represents a hydrogen atom, halogen atom, alkyl or aromatic hydrocarbon group, and A represents a group having a nitrogen-containing six-membered ring quaternary ammonium cation.

6. The white pigment dispersion as described in claim 3, characterized in that: The compound having a phthalimide skeleton and having a carboxyl group attached to the nitrogen atom is selected from at least one of the compounds shown in formula (1) below. In equation (1), R 1 ~R 4 Independently representing a hydrogen atom, halogen atom, alkyl or aromatic hydrocarbon group, X represents a divalent saturated hydrocarbon group with or without substituents or a group represented by formula (2) below, where "*" in formula (2) represents a valence bond.

7. The white pigment dispersion as described in claim 3, characterized in that: The compound having a phthalimide skeleton and having a group containing a nitrogen-containing six-membered ring quaternary ammonium cation attached to the nitrogen atom is selected from at least one of the compounds shown in formula (3) below. In equation (3), R 1 ~R 4 Independently represents a hydrogen atom, halogen atom, alkyl or aromatic hydrocarbon group, and A represents a group having a nitrogen-containing six-membered ring quaternary ammonium cation.

8. A composition for forming a white partition wall, characterized in that: It contains a white pigment dispersion as described in any one of claims 1 to 7, and a component for forming a white partition wall.

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