JP7493301B2 - Thermosetting composition, cured film and display device - Google Patents

Description

The present invention relates to a thermosetting composition, a cured film obtained by curing the composition, and a display device having the cured film.

Conventionally, a transparent cured film (hereinafter also referred to as a protective film) is formed as a protective layer on the surface of a color filter used in the manufacture of a color liquid crystal display (LCD). The protective film of a color filter is formed for the purposes of flattening the unevenness that occurs between the pixels of the color filter, improving the durability of the color filter against heat treatment and chemical treatment in the post-process, and improving the reliability of the color liquid crystal display. The protective film of a color filter is required to have excellent flatness, heat resistance, chemical resistance, adhesion, hardness, electrical reliability, and transparency.

For example, in terms of flatness, it is required to flatten the unevenness of about 1 to 2 μm caused by the overpainting of coloring compositions when forming pixels to 0.1 μm or less. In terms of heat resistance, when a transparent electrode such as ITO is formed on the protective film by sputtering, high heat of about 200 to 270°C may be applied, and the protective film is required to be stable under these temperature conditions. In terms of chemical resistance, it is required that the protective film is stable against acids, alkalis, solvents, etc. used in subsequent processes. In terms of adhesion, when a substrate is laminated on the protective film when a liquid crystal display panel is produced, it is required that the protective film at that part does not peel off from the base. In terms of hardness, it is required that the protective film has high hardness from the viewpoint of durability. In terms of electrical reliability, it is required that the insulating properties of the protective film are maintained, and that impurities contained in the protective film do not contaminate the liquid crystal. In terms of transparency, it is required that the protective film does not absorb in the visible light wavelength range so as not to impair the color characteristics of the color filter.

In addition to the above-mentioned required characteristics for the protective film, the high performance of LCD panels has led to the demand for a wide viewing angle and high-speed response, and as display methods such as IPS (In-plane Switching) mode have come to be used, the required characteristics for the protective film have also become stricter. In display methods such as IPS mode, if gaseous or liquid components or water generated or bled out from the color filter layer enter the liquid crystal layer through the protective layer, the concentration of moisture or ionic impurities in the liquid crystal layer increases, or bubbles form in the liquid crystal, causing display defects. For this reason, it is particularly important to prevent the passage of the above-mentioned impurity components, as well as to have low gas generation properties, since gas generation from the protective film in direct contact with the liquid crystal layer directly leads to display defects. In addition, in recent years, there has been a demand for thinner LCD panels, so there is also a demand for thinner protective films, and the demand for flatness, such as achieving flatness under a thin film, is also becoming stricter. In other words, a new challenge has arisen, such as achieving both low gas generation and flatness.

Many compositions of epoxy or acrylic compounds have been proposed as materials for protective films for color filters (e.g., Patent Documents 1 to 5), but no material has been found that simultaneously satisfies the required characteristics of low gas generation and flatness.

WO 96/34303 JP 2000-103937 A JP 2000-143772 A JP 2001-091732 A JP 2004-069930 A

As mentioned above, protective films for color filters must meet the required characteristics of low gas generation and flatness, while also maintaining high levels of essential properties for protective films for color filters, such as heat resistance, chemical resistance, adhesion, hardness, electrical reliability, and transparency. However, the range of application of protective film materials that can satisfy these requirements is narrowing.

Furthermore, in recent years, in addition to RGB, color filters (RGBW type) have been developed that have white (W) pixels that are not coated with a coloring composition for the color filter pixels, and the protective film is required to satisfy flatness while filling the W space where the coloring composition is not applied. That is, in addition to the conventional unevenness on the pixel of about 1 to 2 μm, it is now required to flatten even larger concave spaces of 2 to 3 μm with a thin film of 2 μm or less on the color pixel formation area.

The present invention has been made in consideration of the above problems, and aims to provide a thermosetting composition capable of forming a protective film that satisfies the required characteristics of flatness and low gas generation while also exhibiting excellent heat resistance, chemical resistance, adhesion, hardness, electrical reliability, and transparency, a cured film obtained by curing the composition, and a display device having the cured film.

As a result of investigations conducted by the inventors to solve the problems required for protective films for color filters, as described above, they discovered that the above problems could be solved by using a thermosetting composition having a specific formulation, and thus completed the present invention.

The present invention relates to (1): a thermosetting composition characterized by containing an epoxy compound (A) represented by the following general formula (1) in which the average value of m is 0 to 1, an epoxy compound (B) that is liquid at room temperature, an epoxy compound (C) other than component (A) or (B) that has a weight average molecular weight of 900 to 20,000 and an epoxy equivalent of 150 to 500 g/eq, a curing agent (D) selected from the group consisting of polycarboxylic acids, anhydrides of polycarboxylic acids, and thermally decomposable esters of polycarboxylic acids, and a curing accelerator (E).

In general formula (1), Ar is a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and some of the hydrogen atoms of the divalent aromatic hydrocarbon group may be substituted with a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen group.

The present invention also relates to (2): the thermosetting composition according to (1), characterized in that, based on the total mass of the solid contents, the total content of the epoxy compounds including the components (A), (B), and (C) is 55 to 85 mass%, the content of the component (D) is 5 to 40 mass%, and the content of the component (E) is 0.01 to 2 mass%.
The present invention also relates to (3): the thermosetting composition according to (1) or (2), characterized in that it contains 1 to 20 mass % of a coupling agent (F) based on the total mass of the solid content.
The present invention also relates to (4): the thermosetting composition according to any one of (1) to (3), characterized in that the content of the component (A) is 5 to 50 mass%, the content of the component (B) is 10 to 40 mass%, and the content of the component (C) is 10 to 70 mass%, based on the total mass of the epoxy compound containing the components (A), (B), and (C).
The present invention also relates to (5): a cured film obtained by curing the thermosetting composition according to any one of (1) to (4).
The present invention also relates to a display device comprising the cured film according to (6): (5).

The thermosetting composition of the present invention satisfies the required characteristics of flatness and low gas generation, and can form a protective film that is also excellent in heat resistance, chemical resistance, adhesion, hardness, electrical reliability and transparency. The thermosetting composition of the present invention can be applied not only as a protective film for the color filter of an LCD including an RGBW type, but also to a display device that requires a transparent cured film that is particularly excellent in flatness and low gas generation. In other words, it can be suitably applied as a component of an organic EL display device other than an LCD, a μLED display device, or a display device that uses quantum dots, especially when a transparent film that flattens unevenness or steps is required. Furthermore, it can be applied to a sensor such as a CMOS equipped with a color filter layer.

The present invention will be described in detail below.
The epoxy compound of the component (A) is an epoxy compound represented by the general formula (1) in which the average value of m is 0 to 1.

In general formula (1), Ar is a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms. In addition, some of the hydrogen atoms of the divalent aromatic hydrocarbon group represented by Ar may be substituted with a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen group.

Component (A) can be a bisphenolfluorene type epoxy compound or a bisnaphtholfluorene type epoxy compound. Component (A) has a relatively small effect on the viscosity of the thermosetting composition and is an effective component for imparting low gas generation and heat resistance. In particular, for imparting low gas generation, bisnaphtholfluorene type epoxy resins are more preferable, but by optimizing the combination and amount of epoxy resins (B) and (C), it is possible to obtain a thermosetting composition that satisfies the required characteristics of flatness and low gas generation in a protective film of a specific thickness, even when a bisphenolfluorene type epoxy resin is used.

The average value of m in the general formula (1) may be 0 to 1, and if it is 0 or more, the solubility of the component (A) can be increased, while if it exceeds 1, the curing properties of the cured film tend to be insufficient. The average value of m is preferably 0.01 to 0.5, and more preferably 0.02 or more and less than 0.2.
The average value of m can be calculated from the epoxy equivalent of the component (A).
In the case of bisnaphtholfluorene type epoxy compounds, (epoxy equivalent) x 2 = (average value of m) x 506.6 + 562.7
In the case of bisphenol fluorene type epoxy compounds, (epoxy equivalent) x 2 = (average value of m) x 406.5 + 462.5

Component (A) can be synthesized by known methods such as the method described in JP-A-9-328534, but the most common and preferred method is to obtain it by condensing 9,9-bis(4-hydroxyphenyl)fluorene or 9,9-bis(4-hydroxynaphthyl)fluorene with epichlorohydrin in the presence of an alkali. The value of m can be adjusted to the desired value by adjusting the molar ratio of the raw material compounds during synthesis or by adjusting the reaction conditions.

Component (B) is an epoxy compound that is liquid at room temperature.

Component (B) can be any epoxy compound that is liquid at room temperature, including chain aliphatic epoxy compounds, alicyclic epoxy compounds, and aromatic epoxy compounds, without any particular restrictions.

Examples of chain aliphatic epoxy compounds include trimethylolpropane triglycidyl ether, trimethylolethane triglycidyl ether, and mono- or diglycidyl ethers of branched alkyl esters, with the more multifunctional trimethylolpropane triglycidyl ether and diglycidyl ethers of branched alkyl esters being preferred. Aliphatic epoxy compounds contribute to improved heat resistance by improving crosslink density through reaction with a curing agent. In particular, epoxy compounds with a viscosity of 30 to 500 mPa·s (25°C) can be preferably used.

Examples of alicyclic epoxy compounds include (3',4'-epoxycyclohexylmethyl) 3,4-epoxycyclohexanecarboxylate, 2-(3,4-epoxy)cyclohexyl-5,1-spiro(3,4-epoxy)cyclohexyl-m-dioxane, bis(3,4-epoxycyclohexylmethyl)adipate, hydrogenated bisphenol A diglycidyl ether, 1,4-cyclohexanedimethanol-bis 3,4-epoxycyclohexanecarboxylate, etc., and epoxy compounds with a viscosity of 50 to 3500 mPa·s (25°C) can be preferably used.

Examples of aromatic epoxy compounds include low molecular weight compounds such as bisphenol A type epoxy compounds and bisphenol F type epoxy compounds.

Among these, low molecular weight liquid compounds such as (3',4'-epoxycyclohexylmethyl) 3,4-epoxycyclohexane carboxylate and bisphenol A type epoxy resins are more preferably used.

The use of these liquid epoxy resins makes it possible to impart a level of flatness that is difficult to achieve using only component (A), such as bisphenol fluorene or bisnaphthol fluorene epoxy resins.

Component (C) is an epoxy compound other than components (A) and (B), and has a weight average molecular weight of 900 to 20,000 and an epoxy equivalent of 150 to 500 g/eq.

As long as the above requirements are met, component (C) can be any known epoxy compound, including bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, phenol novolac type epoxy compounds, cresol novolac type epoxy compounds, glycidyl ethers of polyhydric alcohols, glycidyl esters of polycarboxylic acids, alicyclic epoxy compounds such as 1,2-epoxy-4-(2-oxiranyl)cyclohexane adducts of 2,2-bis(hydroxymethyl)-1-butanol (e.g., Daicel Corporation's "EHPE3150"), copolymers of (meth)acrylic acid esters containing glycidyl (meth)acrylate as an essential component, epoxidized polybutadiene (e.g., Nippon Soda Co., Ltd.'s "NISSO-PB.JP-100"), and epoxy compounds having a silicone backbone.

The copolymer of two or more (meth)acrylic acid esters, which contains glycidyl (meth)acrylate as an essential component, is a compound obtained by radical copolymerization of glycidyl (meth)acrylate with (meth)acrylic esters and other polymerizable unsaturated compounds by a conventional method. In the above radical copolymerization, a known radical polymerization initiator such as an azo compound or a peroxide can be used. In addition, the degree of polymerization can be controlled so that the weight average molecular weight is 900 to 20,000 by using a known chain transfer agent or polymerization inhibitor.

The (meth)acrylic esters other than glycidyl (meth)acrylate and other polymerizable unsaturated compounds used in the above copolymer are exemplified below, but are not limited to these.

(Meth)acrylic acid esters can be obtained by a condensation reaction between (meth)acrylic acid ((meth)acrylic acid refers to acrylic acid or methacrylic acid) and an alcohol (R ¹ OH) component. As the (R ¹ OH) component, any known compound can be used without any particular limitation. Specific examples of R ¹ include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, an octadecyl group, an icosyl group, a cyclopropyl group, a cyclopentyl group, a cyclopentylethyl group, a cyclohexyl group, a cyclohexylmethyl group, a 4-methylcyclohexyl group, an adamantyl group, an isobornyl group, a dicyclopentamethyl group, a cyclopentyl ... Examples of the alkyl group include saturated or unsaturated monovalent hydrocarbon groups such as a pyridyl group, a piperidyl group, a piperidino group, a pyrrolyl group, a pyrrolidinyl group, an imidazolyl group, an imidazolidinyl group, a furyl group, a tetrahydrofuryl group, a thienyl group, a tetrahydrothienyl group, a morpholinyl group, a morpholino group, and a quinolyl group. The above-mentioned hydrocarbon group or heterocyclic group may have a structure in which a halogen atom, a carbonyl group, a thiocarbonyl group, a nitro group, a silyl group, an ether group, a thioether group, an ester group, a thioester group, a dithioester group, a urethane group, a thiourethane group, a ureido group, a thioureido group, or the like is introduced as a substituent at any position. Such a monovalent group may be appropriately selected depending on the structure of the intended component (C), but from the viewpoint of performance and economy, it is preferably a saturated or unsaturated monovalent hydrocarbon group having 1 to 20 carbon atoms, and more preferably a saturated or unsaturated monovalent hydrocarbon group having 1 to 6 carbon atoms. The saturated or unsaturated monovalent hydrocarbon group may be a hydrocarbon group having a branched structure or a ring structure, and may further be substituted with any substituent. However, it is preferable that the above-mentioned substituent does not have a reactive structure such as an acidic group.

Other polymerizable unsaturated compounds include styrene and its derivatives. Specific compounds that can be used include styrene, α-methylstyrene, and compounds in which an alkyl group, a halogen atom, a hydroxyl group, etc. is introduced into the aromatic ring of styrene.

In addition to the above, component (C) may also be copolymerized with epoxy group-containing polymerizable unsaturated compounds other than glycidyl methacrylate (e.g., glycidyl acrylate, (meth)acrylate [4-(glycidyloxy)butyl], (meth)acrylate [(3,4-epoxycyclohexyl)methyl], and 4-(glycidyloxymethyl)styrene, etc.), as well as alkoxysilyl group-containing polymerizable unsaturated compounds (e.g., (meth)acrylate [3-(trimethoxysilyl)propyl], (meth)acrylate [3-(triethoxysilyl)propyl], and 4-(trimethoxysilyl)styrene, etc.).

Among the copolymers listed above, preferred examples include copolymers of glycidyl methacrylate, alkyl methacrylate esters (C1-C4 alkyl groups), and copolymers of styrene, which have a softening point (Tg) of 10-90°C. The more preferred range for the Tg of the copolymer is 40-90°C.

The weight average molecular weight (Mw) of component (C) is 900 to 20,000, preferably 2,000 to 15,000, and more preferably 3,000 to 13,000. If the weight average molecular weight is greater than 20,000, the flatness of the cured film is likely to decrease. In addition, since it is generally difficult to control the polymerization reaction to obtain an epoxy compound with a weight average molecular weight of less than 900, it is difficult to imagine an epoxy compound with a weight average molecular weight of less than 900. The weight average molecular weight of component (C) can be determined by GPC (SEC) measurement.

The epoxy equivalent of component (C) is 150 to 500 g/eq, and preferably 200 to 490 g/eq. If the epoxy equivalent is greater than 500 g/eq, the epoxy group content decreases, resulting in insufficient curing and poor properties of the cured film. In addition, since the epoxy equivalent when only glycidyl methacrylate is polymerized is 142 g/eq, epoxy compounds with an epoxy equivalent of less than 150 g/eq are difficult to imagine due to restrictions in their chemical structure.

In order to set the epoxy equivalent within the above range, the proportion of repeating units derived from glycidyl methacrylate in the total number of repeating units derived from the polymerizable unsaturated compounds constituting component (C) is preferably 50 mol % or more, and more preferably 65 mol % or more. The proportion of repeating units derived from glycidyl methacrylate above usually reflects the molar ratio of the polymerizable unsaturated compounds used as raw materials when synthesizing component (C).

The thermosetting composition of the present invention may contain an epoxy compound that does not fall under the category of components (A) to (C). Examples of such epoxy compounds include trifunctional epoxy compounds having a triazine skeleton (TEPIC series manufactured by Nissan Chemical Industries, Ltd.) that are solid at room temperature and have an epoxy equivalent outside the range of component (C), and epoxy compounds that are waxy or granular at room temperature and have a low melting point, such as ε-caprolactam modified (3',4'-epoxycyclohexylmethyl) 3,4-epoxycyclohexanecarboxylate (TTA2081, TTA2083 manufactured by Tetrachem Co., Ltd.). It goes without saying that if an epoxy compound with properties within the ranges of components (B) and (C) is developed in the TEPIC series or TTA series, it can be used as components (B) and (C).

Component (D) is a curing agent selected from the group consisting of polycarboxylic acids, anhydrides of polycarboxylic acids, and thermally decomposable esters of polycarboxylic acids.

Polycarboxylic acids are compounds that have two or more carboxy groups in one molecule, and examples include succinic acid, maleic acid, cyclohexane-1,2-dicarboxylic acid, cyclohexene-1,2-dicarboxylic acid, cyclohexene-4,5-dicarboxylic acid, norbornane-2,3-dicarboxylic acid, phthalic acid, benzene-1,2,4-tricarboxylic acid, cyclohexane-1,2,4-tricarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid, cyclohexane-1,2,4,5-tetracarboxylic acid, and butane-1,2,3,4-tetracarboxylic acid.

Examples of the anhydrides of polycarboxylic acids include the acid anhydrides of the polycarboxylic acids exemplified above. These may be intermolecular acid anhydrides, but acid anhydrides that have undergone intramolecular ring closure are generally used. An example of a preferred acid anhydride is trimellitic anhydride.

Examples of thermally decomposable esters of polycarboxylic acids include t-butyl esters, 1-(alkyloxy)ethyl esters, and 1-(alkylsulfanyl)ethyl esters of the above-listed polycarboxylic acids (wherein alkyl represents a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, and such a hydrocarbon group may have a branched or cyclic structure, and may be substituted with any substituent).

Also, as component (D), a polymer or copolymer having two or more carboxy groups can be used. The carboxy group of the polymer or copolymer may be an anhydride or a thermally decomposable ester. Examples of such polymers or copolymers include a polymer or copolymer containing (meth)acrylic acid as a constituent component, a copolymer containing maleic anhydride as a constituent component, and a compound obtained by reacting a tetracarboxylic dianhydride with a diamine or diol to open the ring of the acid anhydride.

Component (E) is a curing accelerator.

Component (E) may be a known compound known as a curing accelerator, curing catalyst, or latent curing agent for epoxy compounds. Examples of component (E) include tertiary amines, quaternary ammonium salts, tertiary phosphines, quaternary phosphonium salts, boric acid esters, Lewis acids, organometallic compounds, and imidazoles, with 1,8-diazabicyclo[5.4.0]undec-7-ene or 1,5-diazabicyclo[4.3.0]non-5-ene or salts thereof being particularly preferred.

Component (F) is a coupling agent.

Component (F) can be a silane coupling agent (such as 3-(glycidyloxy)propyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, and 3-ureidopropyltriethoxysilane), a titanium-based coupling agent, or an aluminum-based coupling agent.

The thermosetting composition of the present invention may contain a solvent (G). Known compounds may be used as the solvent, and examples of such solvents include ester-based solvents (butyl acetate, cyclohexyl acetate, etc.), ketone-based solvents (methyl isobutyl ketone, cyclohexanone, etc.), ether-based solvents (diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, etc.), alcohol-based solvents (3-methoxybutanol, ethylene glycol mono-t-butyl ether, etc.), aromatic solvents (toluene, xylene, etc.), aliphatic solvents, amine-based solvents, and amide-based solvents, etc., may be used without particular limitation. From the standpoint of safety, ester-based and ether-based solvents having a propylene glycol skeleton, such as propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and propylene glycol diacetate, are preferred. Also preferred are 3-methoxybutyl acetate, 3-methoxy-3-methylbutyl acetate, and 1,3-butylene glycol diacetate, which have a similar structure.

There are no particular restrictions on the solids concentration of the thermosetting composition, but for use as a protective film for a color filter, the solids concentration, which is the total amount of components other than the solvent, is generally adjusted to a range of 10 to 30 mass %. In addition, in order to improve the flatness of the protective film for a color filter, it is preferable to control the drying property of the thermosetting composition by using a combination of 40 to 90 mass % of a solvent with a boiling point of less than 150°C at normal pressure and 10 to 60 mass % of a solvent with a boiling point of 150°C or higher at normal pressure.

In the thermosetting composition of the present invention, the total content (A+B+C) of the epoxy compounds including the (A), (B) and (C) components is preferably 55 to 85% by mass, more preferably 60 to 80% by mass, based on the total mass of the solid content. If (A+B+C) is less than 55% by mass, the ratio of the curing agent to (A+B+C) becomes large, and the properties of the cured product of the epoxy compound are not sufficiently obtained, or the excess cured product that does not contribute to the curing reaction adversely affects the gas generation. If (A+B+C) exceeds 85% by mass, the ratio of the curing agent to (A+B+C) becomes extremely small, the curing reaction does not proceed sufficiently, the heat resistance of the cured product is insufficient, and the adverse effect on the gas generation is also large, especially when the (B) component becomes excessive.

In the thermosetting composition of the present invention, the content of component (A) is preferably 5 to 50 mass%, more preferably 10 to 50 mass%, based on the total mass of the epoxy compound. In addition, in the thermosetting composition of the present invention, the content of component (B) is preferably 10 to 40 mass%, more preferably 20 to 40 mass%, based on the total mass of the epoxy compound. In addition, in the thermosetting composition of the present invention, the content of component (C) is preferably 10 to 70 mass%, more preferably 10 to 50 mass%, based on the total mass of the epoxy compound.

In the thermosetting composition of the present invention, the content of component (D) is preferably 5 to 40% by mass, and more preferably 10 to 30% by mass, based on the total mass of solids. If the content of component (D) is less than 5% by mass, the curing reaction does not proceed sufficiently, and the cured product does not have sufficient physical properties, such as insufficient heat resistance, and in particular, if there is an excess of component (B), this has a significant adverse effect on gas generation. If the content of component (D) exceeds 40% by mass, the excess cured product that does not contribute to the curing reaction has an adverse effect on gas generation, and the properties of the cured product may not be sufficient.

In the thermosetting composition of the present invention, from the viewpoint of balancing the effect of promoting curing and storage stability while ensuring the transparency of the cured film, the content of component (E) is preferably 0.01 to 2 mass%, and more preferably 0.05 to 1.5 mass%, based on the total mass of solids. If the content of component (E) is less than 0.01 mass%, the accelerator effect is poor, and it is difficult to obtain a cured product with sufficient physical properties. If the content of component (E) is more than 2 mass%, the thermosetting composition solution may not have sufficient storage stability or may have an adverse effect on coloring during heating.

The thermosetting composition of the present invention can be used with a content of component (F) of 1 to 20% by mass based on the total mass of the solid content. If the content of component (F) is less than 1% by mass, adhesion to the coated lower layer tends to be insufficient, and if the content of component (F) exceeds 20% by mass, the excess component (F) that does not contribute to adhesion will deteriorate gas generation. When used as a protective film for a color filter, if the lower layer is an organic layer such as an RGB pixel, the content is preferably 1 to 10% by mass, and if adhesion to layers other than the organic layer is also an issue, such as in the case of direct contact with a glass substrate as in the RGBW method, the content is preferably 5 to 20% by mass. If it does not depend on the type of lower layer, a more preferable range is 5 to 15% by mass.

The thermosetting composition of the present invention may contain other optional components as necessary, for example, coloring materials, fillers, resins, additives, etc. Here, examples of coloring materials include dyes, organic pigments, inorganic pigments, carbon black pigments, etc.; examples of fillers include silica, talc, etc.; examples of resins include vinyl resins, polyester resins, polyamide resins, polyimide resins, polyurethane resins, polyether resins, melamine resins, etc.; examples of additives include crosslinking agents, dispersants, surfactants, silane coupling agents, viscosity modifiers, wetting agents, defoamers, antioxidants, ultraviolet absorbers, etc. As these optional components, known compounds can be used without particular restrictions. When used as a protective film for a color filter, surfactants (fluorine-based surfactants, silicone-based surfactants, etc.) may be used, but it is preferable that the total content of the surfactants is up to 10 mass% of the solid content of the thermosetting composition.

A known method can be used to prepare a cured product of the thermosetting composition of the present invention. For example, the thermosetting composition can be applied or injected into an appropriate substrate or mold according to the purpose and application, and then the composition can be heated to remove the solvent and harden the composition. Reduced pressure drying or the like can also be used to remove the solvent.

The cured product of the thermosetting composition of the present invention can be a film-like cured film. The cured film can be prepared by applying it to the surface of a coloring composition for pixels applied to a substrate of a color filter and curing it to prepare a protective film for the color filter. In this case, when preparing a color filter having white (W) pixels in which a coloring composition for pixels of a color filter is not applied in addition to RGB, if the thermosetting composition of the present invention is applied and cured to prepare a protective film, the space W of about 1.0 to 3.0 μm deep formed due to the absence of application of the coloring composition can be filled, and the flatness between the surface of the protective film formed on the RGB coloring composition applied to the substrate and the surface of the protective film formed on the space W can be satisfied.

The cured product of the thermosetting composition of the present invention can be used as a protective film for the color filter of LCDs including RGBW type, and can also be used for display devices that require a transparent cured film with excellent flatness and low gas generation. That is, it can be suitably used as a component of organic EL display devices other than LCDs, μLED display devices, and display devices using quantum dots, especially when a transparent film that flattens unevenness and steps is required. Furthermore, it can be applied to sensors such as CMOS equipped with a color filter layer. In addition, the cured product of the thermosetting composition of the present invention can fill the above-mentioned step parts while increasing the flatness of the surface, so it can be used for resist layers such as solder resist layers, plating resist layers, and etching resist layers, interlayer insulating layers such as multilayer printed wiring boards, gas barrier films, sealing materials for lenses and semiconductor light-emitting elements such as light-emitting diodes (LEDs), top coats for paints and inks, hard coats for plastics, and rust-proof films for metals. In addition, it is extremely useful not only as a coating agent, but also because the thermosetting composition itself can be molded to produce films, substrates, plastic parts, optical lenses, etc.

The following describes the embodiments of the present invention in detail based on examples and comparative examples, but the present invention is not limited to these.

[Synthesis Example 1]
451 parts by mass of 9,9-bis(4-hydroxynaphthyl)fluorene and 555 parts by mass of epichlorohydrin were charged into a reaction vessel equipped with a stirrer, a condenser, and an oil-water separation tube capable of a reduced pressure reaction, and after complete dissolution, the pressure in the system was reduced to 20 kPa and 73°C, and then 129.2 parts by mass of a 49% NaOH aqueous solution was dropped over 3 hours. During the reaction, the reaction was carried out in a reflux state, and the water and epichlorohydrin distilled from the reflux were separated using an oil-water separation tube, and the epichlorohydrin was returned to the reaction vessel, and the water was removed from the system and reacted. After the reaction was completed, epichlorohydrin was distilled off and dissolved in 600 parts by mass of toluene. The salt formed was then removed, and the mixture was further washed with water, after which 36.5 parts by mass of a 49% NaOH solution and 14.5 parts by mass of water were added and heated and stirred at 80°C for 3 hours to purify. After purification, the mixture was repeatedly washed with water to wash out impurities such as salts. Toluene was recovered from the washed toluene solution to obtain 380 parts by mass of an epoxy compound (epoxy compound (A)-1). The epoxy equivalent of the obtained resin was 296 g/eq.

[Synthesis Example 2]
Epoxy compound (A)-2 was obtained by carrying out reaction and purification in the same manner as in Synthesis Example 1, except that 350 parts by mass of 9,9-bis(4-hydroxyphenyl)fluorene was used instead of 451 parts by mass of 9,9-bis(4-hydroxynaphthyl)fluorene in Synthesis Example 1. The epoxy equivalent of the obtained resin was 257 g/eq.

(Preparation of Thermosetting Composition)
The compositions shown in Tables 1 to 5 were blended, and the solid components were dissolved in the solvent by stirring and mixing at room temperature for 3 hours to prepare thermosetting compositions. The composition values are in parts by mass, and are listed so that the total solid content is 100 parts by mass. Some solid components were synthesized in a state dissolved in a solvent (propylene glycol monomethyl ether acetate) from the beginning, and in that case the composition values show the parts by mass of the solid content, and the solvent content brought in is included in the parts by mass of the solvent. The components used in the blends of the examples are shown below.

(Component (A): Epoxy compound represented by general formula (1))
(A)-1: Bisnaphtholfluorene type epoxy compound having an average value of m of 0.06 in general formula (1) prepared in Synthesis Example 1. (A)-2: Bisphenolfluorene type epoxy compound having an average value of m of 0.12 in general formula (1) prepared in Synthesis Example 2.

(Component (B): Epoxy compound that is liquid at room temperature)
(B)-1: (3',4'-epoxycyclohexylmethyl) 3,4-epoxycyclohexanecarboxylate (Celloxide 2021P, manufactured by Daicel Corporation, epoxy equivalent: 135)
(B)-2: Bisphenol A type epoxy compound (JER828 manufactured by Mitsubishi Chemical, epoxy equivalent: 190)

(Component (C): an epoxy compound having a weight average molecular weight of 900 to 20,000 and an epoxy equivalent of 150 to 500 g/eq)
(C)-1: 1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (manufactured by Daicel Corporation, EHPE3150, Mw: about 1400, epoxy equivalent: 170 to 190 g/eq)
(C)-2: glycidyl methacrylate copolymer having a copolymerization composition of glycidyl methacrylate:methyl methacrylate:n-butyl methacrylate=5:3:2 (Mw: about 9000, epoxy equivalent: 295 g/eq)
(C)-3: Bisphenol A type epoxy resin (manufactured by Mitsubishi Chemical Corporation, JER1001, Mw: about 900, epoxy equivalent: 450 to 500 g/eq)

(Component (D): Curing Agent)
(D): Trimellitic anhydride

(Component (E): Curing Accelerator)
(E): Octylate salt of 1,8-diazabicyclo[5.4.0]undec-7-ene

(Component (F): Coupling Agent)
(F): 3-(glycidyloxy)propyltrimethoxysilane

(Component (G): Solvent)
(G)-1: Propylene glycol monomethyl ether acetate (G)-2: Methyl 3-methoxypropionate (G)-3: Diethylene glycol ethyl methyl ether

(Component (S): Other Components)
(S): Fluorine-based surfactant (MEGAFAC F-556, manufactured by DIC Corporation)

(Evaluation of Thermosetting Composition: Flatness)
A color filter substrate was prepared in which a black matrix, red, green, and blue pixels, and a mosaic pattern without blue pixels were formed, and unevenness of 2.5 μm in height was generated on the pixels. The above-mentioned thermosetting composition was applied to the color filter substrate using a spin coater, and dried on a hot plate at 90° C. for 2 minutes to prepare a test piece. At this time, the application conditions (spin rotation speed) were adjusted so that a cured film with a film thickness of 1.5 μm was obtained on the pixel. Next, the test piece was baked in a hot air oven at 230° C. for 30 minutes to obtain a cured film of the thermosetting composition.

The height of the unevenness at two arbitrarily selected points on the surface of the cured film formed to protect the pixels was measured with a contact surface roughness meter (product name: Microprofile Measuring Instrument ET-4000A, manufactured by Kosaka Laboratory Co., Ltd.), and evaluated into three levels according to the following criteria.
◎ (Good): The difference in height of the unevenness was 0.10 μm or less. ○ (Fair): The difference in height of the unevenness was more than 0.10 μm and 0.15 μm or less. △ (Fair): The difference in height of the unevenness was more than 0.15 μm and 0.20 μm or less. × (Fair): The difference in height of the unevenness was more than 0.2 μm.

(Evaluation of Thermosetting Composition: Gas Generation)
The above thermosetting composition was applied to an alkali-free glass substrate using a spin coater, and dried on a hot plate at 90 ° C for 2 minutes to prepare a test piece. At this time, the application conditions (spin rotation speed) were adjusted so that a cured film with a film thickness of 1.5 μm was obtained. Next, the test piece was baked in a hot air oven at 230 ° C for 30 minutes to obtain a cured film of the thermosetting composition. 10 mg of the cured film of the test piece was scraped off and sampled, and the sample was heated from room temperature to 120 ° C at a rate of 10 ° C / min under air flow, held at 120 ° C for 30 minutes, and then held at 230 ° C for 3 hours at a rate of 10 ° C / min from 120 ° C to 230 ° C. The weight loss was measured with a thermogravimetric analyzer (product name: Rigaku Corporation Differential Thermobalance Thermo plus EVO2), and three-stage evaluation was performed according to the following criteria.
◎: Weight loss was less than 5%. ○: Weight loss was 5% or more but less than 7%. △: Weight loss was 7% or more but less than 10%. ×: Weight loss was 10% or more.

(Evaluation of Thermosetting Composition: Chemical Resistance)
Test pieces on which a cured film of the thermosetting composition was formed were prepared in the same manner as in the gas generation evaluation described above. The test pieces were immersed in N-methylpyrrolidone at 40° C. for 30 minutes, and then the state of the cured film was observed and evaluated on a three-level scale according to the following criteria.
○: No change in appearance and change in film thickness was within 2%. △: No change in appearance, but change in film thickness was more than 2%. ×: Change in appearance was observed.

(Evaluation of Thermosetting Composition: Adhesion)
Test pieces on which a cured film of the thermosetting composition was formed were prepared in the same manner as in the gas generation evaluation described above. The test pieces were held in an environment of 121°C and 100% humidity for 5 hours using an environmental tester, and then a cross-cut tape peel test was performed on the cured film, and the film was evaluated on a 6-level scale from 5B to 0B according to the standard of ASTM D3359.

(Evaluation of Thermosetting Composition: Electrical Reliability)
A test piece having a cured film of the thermosetting composition formed thereon was prepared in the same manner as in the gas generation evaluation described above. 40 mg of the cured film of the test piece was scraped off to obtain a sample, which was then immersed in 1 g of liquid crystal ("MLC-6608" manufactured by Merck) and held at 100°C for 72 hours, after which the voltage holding rate of the liquid crystal was measured and evaluated on a three-level scale according to the following criteria:
○: The voltage retention rate was 95% or more. △: The voltage retention rate was 90% or more but less than 95%. ×: The voltage retention rate was less than 90%.

(Evaluation of Thermosetting Composition: Transparency)
Test pieces each having a cured film of the thermosetting composition formed thereon were prepared in the same manner as in the gas generation evaluation described above. The transmittance of the cured film at a wavelength of 400 nm was measured with a spectrophotometer and evaluated on a three-level scale according to the following criteria.
○: The transmittance was 95% or more. △: The transmittance was 93% or more but less than 95%. ×: The transmittance was less than 93%.

The evaluation results for each thermosetting composition are shown in Tables 6 to 10.

The results of Examples 1 to 18 and Comparative Examples 21 to 32 show that the thermosetting compositions of each Example simultaneously satisfy the flatness, heat resistance, adhesion, and hardness required for a protective film for a color filter, and furthermore have excellent chemical resistance, electrical reliability, and transparency.

Claims (5)

The epoxy compound (A) is represented by the following general formula (1) and has an average value of m of 0 to 1; an epoxy compound (B) which is liquid at room temperature; an epoxy compound (C) other than component (A) or component (B) which has a weight average molecular weight of 900 to 20,000 and an epoxy equivalent of 200 to 490 g/eq; a curing agent (D) selected from the group consisting of polycarboxylic acids and anhydrides of polycarboxylic acids (excluding compounds represented by the following general formula (I)) ; and a curing accelerator (E);
A thermosetting composition characterized in that, relative to the total mass of an epoxy compound containing components (A), (B), and (C), the content of component (A) is 5 to 50 mass%, the content of component (B) is 10 to 40 mass%, and the content of component (C) is 10 to 70 mass%, and the composition is used for producing a film for planarizing unevenness or steps .

In general formula (1), Ar is a divalent aromatic hydrocarbon group having 6 to 12 carbon atoms, and some of the hydrogen atoms of the divalent aromatic hydrocarbon group may be substituted with a hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a halogen group.

In general formula (I), R ¹ 's each independently represent a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group; q represents the number of substituents R ¹ and is an integer of 1 to 4; and P is any one of x, y, and z as follows:

(In formula x, a plurality of R2 ^may exist per ring, and each R2 independently represents a hydrogen atom or a methyl group. * represents a bond to an oxygen atom.)
y. A chain alkylene linker having 6 to 20 carbon atoms, a main chain having 3 or more carbon atoms, and at least one alkyl group substituted thereon.

(In formula z, R each independently represents a hydrogen atom, an alkyl group having 1 to 15 carbon atoms, or a carboxyl group. Of the four *'s, two are bonding sites to oxygen atoms, and the remaining two are bonding to hydroxyl groups. *'s are bonding sites to oxygen atoms.) The thermosetting composition according to claim 1, characterized in that the total content of the epoxy compounds including the components (A), (B), and (C) is 55 to 85 mass%, the content of the component (D) is 5 to 40 mass%, and the content of the component (E) is 0.01 to 2 mass%, based on the total mass of the solid content. The thermosetting composition according to claim 1 or 2, characterized in that it contains 1 to 20 mass % of a coupling agent (F) based on the total mass of the solid content. A cured film formed by curing the thermosetting composition according to any one of claims 1 to 3. A display device having the cured film according to claim 4.