JP7150560B2 - Cured film forming composition and cured film forming method - Google Patents

Description

The present invention relates to a cured film-forming composition containing an epoxy compound (A) and hollow silica (B), and a cured film-forming method using the cured film-forming composition.

2. Description of the Related Art Conventionally, various functional films such as insulating films, protective films and antireflection films have been formed by coating various liquid resin compositions.
Specifically, low refractive index films that cover microlenses for image sensors, and low refractive index films for antireflection in liquid crystal displays, organic EL devices, etc., are formed into desired shapes using photosensitive resin compositions. It is formed while being patterned.

The photosensitive resin composition capable of forming a patterned cured film that can be used as the antireflection low refractive index film includes hollow or porous particles, a photopolymerization initiator, and an alkali-soluble polymerizable A photosensitive resin composition containing a compound and a particle dispersant has been proposed (Patent Document 1).

JP 2009-271444 A

By using the photosensitive resin composition described in Patent Document 1, a low refractive index film having a smooth surface can be formed without problems.
On the other hand, for the purpose of improving the heat resistance, alkali resistance, solvent resistance, etc. of the low refractive index film, it may be desired to use an epoxy compound instead of the alkali-soluble polymerizable compound. When using an epoxy compound in combination with hollow particles, such as hollow silica, a solvent is used to impart favorable spreadability to the composition.

However, as a result of investigations by the present inventors, when a cured film is formed using a composition containing an epoxy compound, hollow silica, and a solvent, haze unevenness, streak unevenness, and pin marks appear on the surface of the cured film. It was found that problems such as The occurrence of such a problem is conspicuous when a coating method such as slit coating is employed.

The present invention has been made in view of the above problems. Cured film-forming composition containing an epoxy compound (A) and hollow silica (B), capable of forming a cured film while suppressing surface defects, and cured film formation using the cured film-forming composition The object is to provide a method.

The present inventors added a surfactant (C) to the composition when forming a cured film using a composition containing an epoxy compound (A), hollow silica (B), and a solvent (S). In addition, we have found that the above problems can be solved by using one or more high boiling point solvents (SH) having a boiling point of 170 ° C. or higher under atmospheric pressure as the solvent (S). Arrived.

A first aspect of the present invention comprises an epoxy compound (A), hollow silica (B), a surfactant (C), and a solvent (S),
The composition for forming a cured film, wherein the solvent (S) contains one or more high-boiling solvents (SH) having a boiling point of 170° C. or higher under atmospheric pressure.

A second aspect of the present invention is to form a coating film by applying the cured film-forming composition according to the first aspect onto a substrate,
Curing the coating film by heating;
A method for forming a cured film, comprising:

According to the present invention, even if a coating film is formed using a slit coating method or the like that tends to cause surface defects such as haze unevenness, streak unevenness, and pin marks, these surface defects can be suppressed while curing. It is possible to provide a cured film-forming composition containing an epoxy compound (A) and hollow silica (B) capable of forming a film, and a cured film-forming method using the cured film-forming composition.

<<Composition for forming cured film>>
The cured film-forming composition contains an epoxy compound (A), hollow silica (B), a surfactant (C), and a solvent (S). The solvent (S) contains one or more high boiling point solvents (SH) having a boiling point of 170° C. or higher under atmospheric pressure.
After forming a coating film by applying a cured film-forming composition containing an epoxy compound (A) and a hollow silica (B) by a method such as slit coating, dip coating, spray coating, or screen printing coating. The coating film obtained by curing the coating film tends to have surface defects such as haze unevenness, streak unevenness, and pin marks. When slit coating is performed, particularly when slit coating is performed at a coating speed as high as 120 mm/sec or more, such surface defects are conspicuous.
However, when the cured film-forming composition described above is used, these surface defects are less likely to occur during the formation of the cured film.

That is, the cured film-forming composition containing the above-described predetermined components is applied to the substrate by slit coating, particularly by slit coating at a coating speed of 120 mm/sec or more. , to provide a cured film while suppressing surface defects.

<Epoxy compound (A)>
The cured film-forming composition contains an epoxy compound (A) having an epoxy group as a component that cures the high film-forming composition. As the epoxy compound (A), both a resin containing an epoxy group and a non-resin type epoxy compound can be used.
As the epoxy compound, an epoxy group-containing resin is preferable from the viewpoint that the coating film made of the composition for forming a cured film can be easily cured at a low temperature in a short period of time.

Epoxy compound (A) may be used together with a known curing agent or curing accelerator, if necessary. The amount of curing agent or curing accelerator to be used is appropriately determined according to the type.

The epoxy compound (A) preferably has one or more functional groups selected from the group consisting of a carboxy group, a carboxylic anhydride group, a phenolic hydroxyl group, and an amino group.
A carboxy group, a carboxylic anhydride group, a phenolic hydroxyl group, and an amino group all cause a curing reaction with an epoxy group or accelerate the curing reaction of the epoxy group.
Therefore, when the epoxy compound (A) has one or more functional groups selected from the group consisting of a carboxy group, a carboxylic anhydride group, a phenolic hydroxyl group, and an amino group, the composition for forming a cured film has The curable rough product can be cured satisfactorily without containing a curing agent.

When curing the cured film-forming composition, a coating film made of the cured film-forming composition may be placed under reduced pressure conditions as described later. In this case, volatilization or sublimation of the curing agent from the coating film may occur, resulting in uneven curing or slight roughness on the surface of the cured film.
However, when the cured film-forming composition does not contain a curing agent, even when the coating film is placed under reduced pressure conditions in the process of forming the cured film-forming composition, the cured film has a flat surface and is evenly cured. Easy to form.

The epoxy compound (A) is preferably a copolymer of monomers having unsaturated double bonds. When an epoxy compound, which is such a copolymer, is used as the epoxy compound (A), the epoxy compound is a so-called resin, so that the curable composition has excellent film-forming properties.
In addition, the use of an epoxy compound that is a copolymer is preferable in that various properties of the cured film can be easily adjusted by appropriately selecting the monomers used for preparing the epoxy compound.

Hereinafter, non-resin type epoxy group compounds and epoxy group-containing resins will be described with respect to specific examples of the epoxy compound (A).

(Non-resin type epoxy compound)
Various widely known epoxy compounds can be used as the non-resin type epoxy compound. The molecular weight of such epoxy compounds is not particularly limited. Among epoxy compounds, polyfunctional epoxy compounds having two or more epoxy groups in the molecule are preferred because they easily form a cured film having excellent heat resistance, chemical resistance, mechanical properties, and the like.

The polyfunctional epoxy compound is not particularly limited as long as it is a difunctional or higher epoxy compound. Examples of polyfunctional epoxy compounds include bifunctional epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AD type epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin; Glycidyl ester-type epoxy resins such as dimer acid glycidyl ester and triglycidyl ester; glycidylamine-type epoxy resins such as tetraglycidylaminodiphenylmethane, triglycidyl-p-aminophenol, tetraglycidylmethaxylylenediamine, and tetraglycidylbisaminomethylcyclohexane Resins; heterocyclic epoxy resins such as triglycidyl isocyanurate; -epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-(2,3-epoxypropoxy)phenyl]ethyl]phenyl]propane, and 1,3-bis[4-[1-[ 4-(2,3-epoxypropoxy)phenyl]-1-[4-[1-[4-(2,3-epoxypropoxy)phenyl]-1-methylethyl]phenyl]ethyl]phenoxy]-2-propanol and tetrafunctional epoxy resins such as tetrahydroxyphenylethane tetraglycidyl ether, tetraglycidylbenzophenone, bisresorcinol tetraglycidyl ether, and tetraglycidoxybiphenyl.

Alicyclic epoxy compounds are also preferred as polyfunctional epoxy compounds in that they give cured products with high hardness. Specific examples of alicyclic epoxy compounds include 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane-meta-dioxane and bis(3,4-epoxycyclohexylmethyl)adipate , bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, 3,4-epoxy-6-methylcyclohexyl-3′,4′-epoxy-6′-methylcyclohexanecarboxylate, ε-caprolactone modification 3, 4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate, trimethylcaprolactone-modified 3,4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate, β-methyl-δ-valerolactone-modified 3, 4-epoxycyclohexylmethyl-3′,4′-epoxycyclohexanecarboxylate, methylenebis(3,4-epoxycyclohexane), di(3,4-epoxycyclohexylmethyl)ether of ethylene glycol, ethylenebis(3,4-epoxy cyclohexane carboxylate), dioctyl epoxycyclohexahydrophthalate, and di-2-ethylhexyl epoxycyclohexahydrophthalate, epoxy resins having a tricyclodecene oxide group, and the following formulas (a01-1) to (a01-5) The compound represented by is mentioned.

（式（ａ０１－１）中、Ｚ^０１は単結合又は連結基（１以上の原子を有する二価の基）を示す。Ｒ^ａ０１～Ｒ^ａ０１８は、それぞれ独立に、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。） Among the specific examples of these alicyclic epoxy compounds, alicyclic epoxy compounds represented by the following formulas (a01-1) to (a01-5) are preferable because they give cured products with high hardness.

(In formula (a01-1), Z ⁰¹ represents a single bond or a linking group (a divalent group having one or more atoms). R ^a01 to R ^a018 each independently represent a hydrogen atom, a halogen atom, and It is a group selected from the group consisting of organic groups.)

The linking group Z ⁰¹ includes, for example, a divalent hydrocarbon group, —O—, —O—CO—, —S—, —SO—, —SO ₂ —, —CBr ₂ —, —C(CBr ₃ ) ₂ -, -C(CF ₃ ) ₂ -, and -R ^a019 -O-CO-, a divalent group selected from the group consisting of a group consisting of a plurality of such groups, and the like.

Examples of the divalent hydrocarbon group that is the linking group Z include a linear or branched alkylene group having from 1 to 18 carbon atoms, a divalent alicyclic hydrocarbon group, and the like. can. Examples of linear or branched alkylene groups having 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, dimethylene and trimethylene groups. Examples of the divalent alicyclic hydrocarbon group include 1,2-cyclopentylene group, 1,3-cyclopentylene group, cyclopentylidene group, 1,2-cyclohexylene group, 1,3- Cycloalkylene groups (including cycloalkylidene groups) such as a cyclohexylene group, a 1,4-cyclohexylene group and a cyclohexylidene group can be mentioned.

R ^a019 is an alkylene group having 1 to 8 carbon atoms, preferably a methylene group or an ethylene group.

（式（ａ０１－２）中、Ｒ^ａ０１～Ｒ^ａ０１８は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ａ０２及びＲ^ａ０１０は、互いに結合してもよい。Ｒ^ａ０１３及びＲ^ａ０１６は互いに結合して環を形成してもよい。ｍ^ａ１は、０又は１である。）

(In formula (a01-2), R ^a01 to R ^a018 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^a02 and R ^a010 may be bonded to each other. R ^a013 and R ^a016 may combine with each other to form a ring, and m ^a1 is 0 or 1.)

（式（ａ０１－２－１）中、Ｒ^ａ０１～Ｒ^ａ０１２は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ａ０２及びＲ^ａ０１０は互いに結合して環を形成してもよい。） The alicyclic epoxy compound represented by the above formula (a01-2) is represented by the following formula (a01-2-1), which corresponds to a compound in which m ^a1 in the above formula (a01-2) is 0. are preferred.

(In formula (a01-2-1), R ^a01 to R ^a012 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^a02 and R ^a010 are bonded to each other to form a ring; may form.)

（式（ａ０１－３）中、Ｒ^ａ０１～Ｒ^ａ０１０は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ａ０２及びＲ^ａ０８は、互いに結合してもよい。）

(In formula (a01-3), R ^a01 to R ^a010 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^a02 and R ^a08 may be bonded to each other. )

（式（ａ０１－４）中、Ｒ^ａ０１～Ｒ^ａ０１２は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。Ｒ^ａ０２及びＲ^ａ０１０は、互いに結合してもよい。）

(In formula (a01-4), R ^a01 to R ^a012 are groups selected from the group consisting of a hydrogen atom, a halogen atom, and an organic group. R ^a02 and R ^a010 may be bonded to each other. )

（式（ａ０１－５）中、Ｒ^ａ０１～Ｒ^ａ０１２は、水素原子、ハロゲン原子、及び有機基からなる群より選択される基である。）

(In formula (a01-5), R ^a01 to R ^a012 are groups selected from the group consisting of hydrogen atoms, halogen atoms, and organic groups.)

In formulas (a01-1) to (a01-5), when R ^a01 to R ^a018 are organic groups, the organic groups are not particularly limited as long as they do not hinder the object of the present invention. , a group consisting of a carbon atom and a halogen atom, or a group containing a heteroatom such as a halogen atom, an oxygen atom, a sulfur atom, a nitrogen atom, a silicon atom in addition to a carbon atom and a hydrogen atom. . Examples of halogen atoms include chlorine, bromine, iodine, and fluorine atoms.

The organic group includes a hydrocarbon group, a group consisting of a carbon atom, a hydrogen atom, and an oxygen atom, a halogenated hydrocarbon group, a group consisting of a carbon atom, an oxygen atom, and a halogen atom, a carbon atom, and a hydrogen atom. , an oxygen atom and a halogen atom are preferred. When the organic group is a hydrocarbon group, the hydrocarbon group may be an aromatic hydrocarbon group, an aliphatic hydrocarbon group, or a group containing an aromatic skeleton and an aliphatic skeleton. The number of carbon atoms in the organic group is preferably 1 or more and 20 or less, more preferably 1 or more and 10 or less, and particularly preferably 1 or more and 5 or less.

Specific examples of hydrocarbon groups include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group and n-hexyl group. , n-heptyl group, n-octyl group, 2-ethylhexyl group, n-nonyl group, n-decyl group, n-undecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group , n-heptadecyl group, n-octadecyl group, n-nonadecyl group, and chain alkyl groups such as n-icosyl group; vinyl group, 1-propenyl group, 2-n-propenyl group (allyl group), 1-n -chain alkenyl groups such as butenyl group, 2-n-butenyl group, and 3-n-butenyl group; cycloalkyl groups such as cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, and cycloheptyl group; phenyl group , o-tolyl group, m-tolyl group, p-tolyl group, α-naphthyl group, β-naphthyl group, biphenyl-4-yl group, biphenyl-3-yl group, biphenyl-2-yl group, anthryl group, and aryl groups such as phenanthryl group; and aralkyl groups such as benzyl group, phenethyl group, α-naphthylmethyl group, β-naphthylmethyl group, α-naphthylethyl group, and β-naphthylethyl group.

Specific examples of halogenated hydrocarbon groups include chloromethyl group, dichloromethyl group, trichloromethyl group, bromomethyl group, dibromomethyl group, tribromomethyl group, fluoromethyl group, difluoromethyl group, trifluoromethyl group, 2,2 , 2-trifluoroethyl group, pentafluoroethyl group, heptafluoropropyl group, perfluorobutyl group, perfluoropentyl group, perfluorohexyl group, perfluoroheptyl group, perfluorooctyl group, perfluorononyl group, and Halogenated chain alkyl groups such as perfluorodecyl group; 2-chlorocyclohexyl group, 3-chlorocyclohexyl group, 4-chlorocyclohexyl group, 2,4-dichlorocyclohexyl group, 2-bromocyclohexyl group, 3-bromocyclohexyl group , and halogenated cycloalkyl groups such as 4-bromocyclohexyl group; 2-chlorophenyl group, 3-chlorophenyl group, 4-chlorophenyl group, 2,3-dichlorophenyl group, 2,4-dichlorophenyl group, 2,5-dichlorophenyl group , 2,6-dichlorophenyl group, 3,4-dichlorophenyl group, 3,5-dichlorophenyl group, 2-bromophenyl group, 3-bromophenyl group, 4-bromophenyl group, 2-fluorophenyl group, 3-fluorophenyl Halogenated aryl groups such as group, 4-fluorophenyl group; 2-chlorophenylmethyl group, 3-chlorophenylmethyl group, 4-chlorophenylmethyl group, 2-bromophenylmethyl group, 3-bromophenylmethyl group, 4-bromophenyl halogenated aralkyl groups such as a methyl group, a 2-fluorophenylmethyl group, a 3-fluorophenylmethyl group and a 4-fluorophenylmethyl group;

Specific examples of groups consisting of carbon atoms, hydrogen atoms, and oxygen atoms include hydroxy chain groups such as hydroxymethyl group, 2-hydroxyethyl group, 3-hydroxy-n-propyl group, and 4-hydroxy-n-butyl group. Alkyl group; Halogenated cycloalkyl group such as 2-hydroxycyclohexyl group, 3-hydroxycyclohexyl group, and 4-hydroxycyclohexyl group; 2-hydroxyphenyl group, 3-hydroxyphenyl group, 4-hydroxyphenyl group, 2,3 -hydroxyaryl groups such as a dihydroxyphenyl group, a 2,4-dihydroxyphenyl group, a 2,5-dihydroxyphenyl group, a 2,6-dihydroxyphenyl group, a 3,4-dihydroxyphenyl group, and a 3,5-dihydroxyphenyl group hydroxyaralkyl groups such as 2-hydroxyphenylmethyl group, 3-hydroxyphenylmethyl group, and 4-hydroxyphenylmethyl group; methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, tert-butyloxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, 2-ethylhexyloxy group, n-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyloxy group, n-heptadecyloxy group, n-octadecyloxy group, Chain alkoxy groups such as n-nonadecyloxy group and n-icosyloxy group; vinyloxy group, 1-propenyloxy group, 2-n-propenyloxy group (allyloxy group), 1-n-butenyloxy group, 2-n-butenyloxy group and chain alkenyloxy groups such as 3-n-butenyloxy; phenoxy, o-tolyloxy, m-tolyloxy, p-tolyloxy, α-naphthyloxy, β-naphthyloxy, biphenyl-4 -yloxy group, biphenyl-3-yloxy group, biphenyl-2-yloxy group, anthryloxy group, and aryloxy group such as phenanthryloxy group; benzyloxy group, phenethyloxy group, α-naphthylmethyloxy group, Aralkyloxy groups such as β-naphthylmethyloxy group, α-naphthylethyloxy group, and β-naphthylethyloxy group; methoxymethyl group, ethoxymethyl group, n-propoxymethyloxy group; group, 2-methoxyethyl group, 2-ethoxyethyl group, 2-n-propoxyethyl group, 3-methoxy-n-propyl group, 3-ethoxy-n-propyl group, 3-n-propoxy-n-propyl 4-methoxy-n-butyl group, 4-ethoxy-n-butyl group, and alkoxyalkyl group such as 4-n-propoxy-n-butyl group; methoxymethoxy group, ethoxymethoxy group, n-propoxymethoxy group , 2-methoxyethoxy group, 2-ethoxyethoxy group, 2-n-propoxyethoxy group, 3-methoxy-n-propoxy group, 3-ethoxy-n-propoxy group, 3-n-propoxy-n-propoxy group, Alkoxyalkoxy groups such as 4-methoxy-n-butyloxy group, 4-ethoxy-n-butyloxy group, and 4-n-propoxy-n-butyloxy group; 2-methoxyphenyl group, 3-methoxyphenyl group, and 4- Alkoxyaryl groups such as methoxyphenyl group; Alkoxyaryloxy groups such as 2-methoxyphenoxy group, 3-methoxyphenoxy group, and 4-methoxyphenoxy group; Formyl group, acetyl group, propionyl group, butanoyl group, pentanoyl group, hexanoyl aliphatic acyl groups such as groups, heptanoyl groups, octanoyl groups, nonanoyl groups, and decanoyl groups; aromatic acyl groups such as benzoyl groups, α-naphthoyl groups, and β-naphthoyl groups; methoxycarbonyl groups, ethoxycarbonyl groups, n -propoxycarbonyl group, n-butyloxycarbonyl group, n-pentyloxycarbonyl group, n-hexylcarbonyl group, n-heptyloxycarbonyl group, n-octyloxycarbonyl group, n-nonyloxycarbonyl group, and n-decyl chain alkyloxycarbonyl groups such as oxycarbonyl group; aryloxycarbonyl groups such as phenoxycarbonyl group, α-naphthoxycarbonyl group, and β-naphthoxycarbonyl group; formyloxy group, acetyloxy group, propionyloxy group, pig Aliphatic acyloxy groups such as a noyloxy group, a pentanoyloxy group, a hexanoyloxy group, a heptanoyloxy group, an octanoyloxy group, a nonanoyloxy group, and a decanoyloxy group; a benzoyloxy group, an α-naphthoyloxy group, and aromatic acyloxy groups such as β-naphthoyloxy groups.

R ^a01 to R ^a018 are each independently preferably a group selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms, All of R ^a01 to R ^a018 are more preferably hydrogen atoms, since a cured film having particularly excellent mechanical properties can be easily formed.

In formulas (a01-2) to (a01-5), R ^a01 to R ^a018 are the same as R ^a01 to R ^a018 in formula (a01-1). In formulas (a01-2) and (a01-4), when R ^a02 and R ^a010 are bonded to each other; in formula (a01-2), when R ^a013 and R ^a016 are bonded to each other; In a01-3), the divalent group formed when R ^a02 and R ^a08 are bonded to each other includes, for example, —CH ₂ — and —C(CH ₃ ) ₂ —.

Among the alicyclic epoxy compounds represented by the formula (a01-1), specific examples of suitable compounds include the following formulas (a01-1a), (a01-1b), and (a01-1c) and 2,2-bis(3,4-epoxycyclohexan-1-yl)propane [=2,2-bis(3,4-epoxycyclohexyl)propane] and the like. can.

Among the alicyclic epoxy compounds represented by formula (a01-2), specific examples of preferred compounds include alicyclic epoxy compounds represented by formula (a01-2a) and formula (a01-2b) below. compound.

Among the alicyclic epoxy compounds represented by formula (a01-3), specific examples of suitable compounds include S-spiro[3-oxatricyclo[3.2.1.0 ^2,4 ]octane-6 , 2′-oxirane] and the like.

Among the alicyclic epoxy compounds represented by formula (a01-4), specific examples of suitable compounds include 4-vinylcyclohexene dioxide, dipentene dioxide, limonene dioxide, 1-methyl-4-(3- methyloxiran-2-yl)-7-oxabicyclo[4.1.0]heptane and the like.

Among the alicyclic epoxy compounds represented by formula (a01-5), specific examples of suitable compounds include 1,2,5,6-diepoxycyclooctane and the like.

(epoxy group-containing resin)
When an epoxy group-containing resin having an epoxy group is used, cross-linking occurs between molecules contained in the resin due to a polyaddition reaction between epoxy groups by using a known curing agent, curing accelerator, or the like as necessary.

The epoxy group-containing resin may be a polymer obtained by polymerizing a monomer having an epoxy group or a monomer mixture containing a monomer having an epoxy group. The epoxy group-containing resin is obtained by introducing an epoxy group into a polymer having a reactive functional group such as a hydroxyl group, a carboxyl group, or an amino group using a compound having an epoxy group such as epichlorohydrin. may Since it is easy to obtain, prepare, and adjust the amount of epoxy groups in the polymer, the polymer having an epoxy group is a monomer having an epoxy group or a monomer containing a monomer having an epoxy group. Polymers obtained by polymerizing a mixture of the two are preferred.

Preferable examples of epoxy group-containing resins include novolak epoxy resins such as phenol novolac epoxy resins, brominated phenol novolac epoxy resins, ortho-cresol novolac epoxy resins, bisphenol A novolak epoxy resins, and bisphenol AD novolac epoxy resins. cycloaliphatic epoxy resins such as epoxidized dicyclopentadiene type phenol resins; and aromatic epoxy resins such as epoxidized naphthalene type phenol resins.

In addition, among epoxy group-containing resins, it is easy to prepare and adjust the physical properties of the cured film. A copolymer of a (meth)acrylic acid ester having and other monomers is preferred.

The (meth)acrylic acid ester having an epoxy group may be a (meth)acrylic acid ester having a chain aliphatic epoxy group, or a (meth)acrylic acid ester having an alicyclic epoxy group as described later. There may be. Moreover, the (meth)acrylic acid ester having an epoxy group may contain an aromatic group. Among (meth)acrylic acid esters having an epoxy group, aliphatic (meth)acrylic acid esters having a chain aliphatic epoxy group and aliphatic (meth)acrylic acid esters having an alicyclic epoxy group are preferred. Aliphatic (meth)acrylic acid esters having an alicyclic epoxy group are more preferred.

Examples of (meth)acrylic acid esters containing an aromatic group and having an epoxy group include 4-glycidyloxyphenyl (meth)acrylate, 3-glycidyloxyphenyl (meth)acrylate, and 2-glycidyloxyphenyl (meth)acrylate. , 4-glycidyloxyphenylmethyl (meth)acrylate, 3-glycidyloxyphenylmethyl (meth)acrylate, and 2-glycidyloxyphenylmethyl (meth)acrylate.

Examples of aliphatic (meth)acrylic acid esters having a chain aliphatic epoxy group include ester groups (-O-CO- ) in which a chain aliphatic epoxy group is bonded to the oxy group (--O--). A chain aliphatic epoxy group possessed by such a (meth)acrylic acid ester may contain one or more oxy groups (--O--) in the chain. The number of carbon atoms in the chain aliphatic epoxy group is not particularly limited, but is preferably 3 or more and 20 or less, more preferably 3 or more and 15 or less, and particularly preferably 3 or more and 10 or less.

Specific examples of aliphatic (meth)acrylic acid esters having a chain aliphatic epoxy group include glycidyl (meth)acrylate, 2-methylglycidyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, 6, Epoxy alkyl (meth) acrylates such as 7-epoxyheptyl (meth) acrylate; 2-glycidyloxyethyl (meth) acrylate, 3-glycidyloxy-n-propyl (meth) acrylate, 4-glycidyloxy-n-butyl (meth) ) acrylate, 5-glycidyloxy-n-hexyl (meth)acrylate, 6-glycidyloxy-n-hexyl (meth)acrylate and other epoxyalkyloxyalkyl (meth)acrylates.

Specific examples of aliphatic (meth)acrylic acid esters having an alicyclic epoxy group include compounds represented by the following formulas (a05-1) to (a05-15). Among these, compounds represented by the following formulas (a05-1) to (a05-5) are preferable, and compounds represented by the following formulas (a05-1) to (a05-3) are more preferable. Further, regarding each of these compounds, the bonding site of the oxygen atom of the ester group to the alicyclic ring is not limited to those shown here, and may include partial positional isomers.

In the above formula, R ^a032 represents a hydrogen atom or a methyl group, R ^a033 represents a divalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, and R ^a034 represents 2 having 1 to 10 carbon atoms. represents a valent hydrocarbon group, and t0 represents an integer of ⁰ or more and 10 or less. R ^a033 is preferably a linear or branched alkylene group such as a methylene group, ethylene group, propylene group, tetramethylene group, ethylethylene group, pentamethylene group and hexamethylene group. R ^a034 is preferably, for example, a methylene group, an ethylene group, a propylene group, a tetramethylene group, an ethylethylene group, a pentamethylene group, a hexamethylene group, a phenylene group and a cyclohexylene group.

As the polymer having an epoxy group, either a homopolymer of a (meth)acrylic acid ester having an epoxy group or a copolymer of a (meth)acrylic acid ester having an epoxy group and another monomer is used. However, the content of units derived from a (meth)acrylic acid ester having an epoxy group in the polymer having an epoxy group is preferably 70% by mass or more, more preferably 80% by mass or more, and 90% by mass. % or more is particularly preferred.

When the polymer having an epoxy group is a copolymer of a (meth)acrylic acid ester having an epoxy group and another monomer, the other monomer may be an unsaturated carboxylic acid or an epoxy group-having polymer. (meth)acrylic acid esters, (meth)acrylamides, allyl compounds, vinyl ethers, vinyl esters, styrenes, etc., which do not contain These compounds can be used alone or in combination of two or more.

Since a cured film can be formed without using a curing agent or a curing accelerator, the polymer having an epoxy group is a copolymer of a (meth)acrylic acid ester having an epoxy group and an unsaturated carboxylic acid. is preferred.

Examples of unsaturated carboxylic acids include (meth)acrylic acid; (meth)acrylamide; crotonic acid; maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, and anhydrides of these dicarboxylic acids.

Examples of (meth)acrylic acid esters having no epoxy group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, amyl (meth)acrylate, t-octyl (meth)acrylate and the like. Chain or branched alkyl (meth)acrylate; chloroethyl (meth)acrylate, 2,2-dimethylhydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, trimethylolpropane mono(meth)acrylate, phenyl (meth) acrylate, 2-methylphenyl (meth) acrylate, 3-methylphenyl (meth) acrylate, 4-methylphenyl (meth) acrylate, 2-hydroxyphenyl (meth) acrylate, 3-hydroxyphenyl (meth) acrylate, 4-hydroxyphenyl (meth)acrylate, naphthalene-1-yl (meth)acrylate, naphthalene-2-yl (meth)acrylate, benzyl (meth)acrylate, furfuryl (meth)acrylate; having a group having an alicyclic skeleton (Meth)acrylic acid esters may be mentioned. Among (meth)acrylic acid esters having no epoxy group, (meth)acrylic acid esters having a group having an alicyclic skeleton are preferred.

In the (meth)acrylic acid ester having a group having an alicyclic skeleton, the alicyclic group constituting the alicyclic skeleton may be monocyclic or polycyclic. A cyclopentyl group, a cyclohexyl group, etc. are mentioned as a monocyclic alicyclic group. Moreover, a norbornyl group, an isobornyl group, a tricyclononyl group, a tricyclodecyl group, a tetracyclododecyl group etc. are mentioned as a polycyclic alicyclic group.

Examples of the (meth)acrylic acid ester having a group having an alicyclic skeleton include compounds represented by the following formulas (a06-1) to (a06-8). Among these, compounds represented by the following formulas (a06-3) to (a06-8) are preferred, and compounds represented by the following formulas (a06-3) or (a06-4) are more preferred.

In the above formula, R ^a035 represents a hydrogen atom or a methyl group, R ^a036 represents a single bond or a divalent saturated aliphatic hydrocarbon group having 1 to 6 carbon atoms, and R ^a037 represents a hydrogen atom or a number of carbon atoms. 1 or more and 5 or less alkyl groups are shown. R ^a036 is preferably a single bond, a linear or branched alkylene group such as a methylene group, an ethylene group, a propylene group, a tetramethylene group, an ethylethylene group, a pentamethylene group and a hexamethylene group. R ^a037 is preferably a methyl group or an ethyl group.

Examples of (meth)acrylamides include (meth)acrylamide, N-alkyl(meth)acrylamide, N-aryl(meth)acrylamide, N,N-dialkyl(meth)acrylamide, N,N-aryl(meth)acrylamide , N-methyl-N-phenyl(meth)acrylamide, N-hydroxyethyl-N-methyl(meth)acrylamide and the like.

Examples of allyl compounds include allyl esters such as allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, and allyl lactate; allyloxyethanol; etc.

Examples of vinyl ethers include hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxy Aliphatic vinyl ethers such as ethyl vinyl ether, diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether; vinyl phenyl ether, vinyl tolyl ether, vinyl chlorophenyl ether, vinyl-2,4 - vinyl aryl ethers such as dichlorophenyl ether, vinyl naphthyl ether and vinyl anthranyl ether;

Examples of vinyl esters include vinyl butyrate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl barate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxy acetate, vinyl butoxy acetate, vinyl phenylacetate, vinylacetoacetate, vinyllactate, vinyl-β-phenylbutyrate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, vinyl tetrachlorobenzoate, vinyl naphthoate and the like.

Examples of styrenes include styrene; methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, butylstyrene, hexylstyrene, cyclohexylstyrene, decylstyrene, benzylstyrene, chloromethylstyrene, trifluoromethylstyrene. , ethoxymethylstyrene, acetoxymethylstyrene; alkoxystyrenes such as methoxystyrene, 4-methoxy-3-methylstyrene, dimethoxystyrene; chlorostyrene, dichlorostyrene, trichlorostyrene, tetrachlorostyrene, pentachlorostyrene, bromo Halostyrenes such as styrene, dibromostyrene, iodostyrene, fluorostyrene, trifluorostyrene, 2-bromo-4-trifluoromethylstyrene, 4-fluoro-3-trifluoromethylstyrene;

The molecular weight of the epoxy group-containing resin is not particularly limited as long as it does not interfere with the object of the present invention. more preferred.

The content of the epoxy compound (A) in the cured film-forming composition is not particularly limited as long as the object of the present invention is not impaired.
The content of the epoxy compound (A) in the cured film-forming composition is relative to the total mass of the epoxy compound (A) and the hollow silica (B), since it facilitates the formation of a cured film. , is preferably 5% by mass or more, more preferably 10% by mass or more.
In addition, from the viewpoint of easy formation of a cured film with a low refractive index, the content of the epoxy compound (A) in the cured film-forming composition is the weight of the epoxy compound (A) and the weight of the hollow silica (B). 50% by mass or less is preferable, 30% by mass or less is more preferable, and 20% by mass or less is particularly preferable with respect to the total.

<Hollow silica (B)>
The curable composition contains hollow silica (B). The refractive index of hollow silica (B) is significantly lower than that of ordinary silica, 1.46. This is because hollow silica (B) contains air with a low refractive index of 1.0.
Therefore, by using a curable composition containing hollow silica (B), a cured film with a low refractive index can be formed.
The refractive index of hollow silica is typically preferably 1.2 or more and 1.3 or less.

As the hollow silica (B), conventionally known ones can be used without particular limitation. Hollow silica may be a commercial product or a synthetic product.
Hollow silica (B) can be used by selecting from known hollow silica in consideration of particle size and refractive index.

The volume average particle diameter of the hollow silica (B) is preferably 50 nm or more and 100 nm or less, more preferably 60 nm or more and 80 nm or less.

The content of the hollow silica (B) in the cured film-forming composition is not particularly limited as long as the object of the present invention is not impaired. The content of the hollow silica (B) in the cured film-forming composition is the total mass of the epoxy compound (A) and the hollow silica (B), since it facilitates the formation of a cured film with a low refractive index. On the other hand, 50% by mass or more is preferable, 70% by mass or more is more preferable, and 80% by mass or more is particularly preferable.

<Surfactant (C)>
The cured film-forming composition contains a surfactant (C). When using a composition for forming a cured film containing a combination of a surfactant (C) and a high boiling point solvent (SH) described later, a coating method such as slit coating that tends to cause surface defects such as unevenness and pin marks. Even if the composition for forming a cured film is applied, it is easy to form a cured film without defects on the surface.
This is probably because the surfactant (C) promotes leveling of the coating film surface during curing of the coating film.

The molecular weight of the surfactant (C) is preferably 2,000 or more, more preferably 3,000 or more, because it is particularly easy to form a cured film having no defects on the surface. The upper limit of the molecular weight of the surfactant (C) is not particularly limited. Typically, the upper limit of the molecular weight of surfactant (C) is 50,000 or less.

The type of surfactant (C) is not particularly limited as long as the desired effect is obtained. Examples of surfactant (C) include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants. Any surfactant can be used. A nonionic surfactant is preferable as the surfactant (C) because the effect of using the surfactant (C) is excellent.
As nonionic surfactants, for example, siloxane surfactants and fluorine surfactants are preferable.

The amount of the surfactant (C) used in the cured film-forming composition is 0.01 parts by mass when the total amount of the epoxy compound (A) and the hollow silica (B) is 100 parts by mass. 10 parts by mass or less is preferable, 0.05 parts by mass or more and 5 parts by mass or less is more preferable, and 0.1 parts by mass or more and 3 parts by mass or less is particularly preferable.

<Solvent (S)>
The cured film-forming composition contains a solvent (S). The solvent (S) contains one or more high boiling point solvents (SH) having a boiling point of 170° C. or higher under atmospheric pressure.
When using a cured film-forming composition containing a combination of the surfactant (C) and a high boiling point solvent (SH), a coating method such as slit coating that tends to cause surface defects such as unevenness and pin marks. Even if the composition for forming a cured film is applied, it is easy to form a cured film without defects on the surface.

When the coating film made of the cured film-forming composition contains a high boiling point solvent (SH), even if most of the solvent (S) is removed from the coating film in the process of curing the coating film, a slight amount of high A boiling point solvent (SH) remains in the coating film. Then, under the influence of the remaining high boiling point solvent (SH), leveling of the surface of the coating film during curing progresses. For these reasons, it is believed that a cured film having a smooth, uniform and preferable surface is formed.

The boiling point of the high boiling point solvent (SH) under atmospheric pressure is preferably 250° C. or lower, more preferably 230° C. or lower. In this case, when the coated film of the cured film-forming composition is cured by heating, the residual amount of the high boiling point solvent (SH) in the cured film is minimized, and a high-quality cured film can be easily formed.

The surface tension at 25° C. of the high boiling point solvent (SH) contained in the solvent (S) is preferably 27 dyn/cm or more in terms of easy formation of a cured film having a preferable smooth and uniform surface. . The surface tension of the high boiling point solvent (SH) at 25° C. is more preferably 28 dyn/cm or more, particularly preferably 30 dyn/cm or more. By using a high-boiling solvent (SH) exhibiting such surface tension, leveling of the surface of the coating film can be favorably progressed during curing of the coating film.
Also, the solvent (S) preferably contains only an organic solvent having a surface tension at 25° C. of 25 dyn/cm or more, preferably 26 dyn/cm or more, more preferably 27 dyn/cm or more.
In this case, during curing of the coating film, the leveling of the coating film surface tends to progress particularly favorably.

The SP value ((cal/cm ³ ) ^1/2 , Fedor) of one or more high boiling point solvents (SH) contained in the solvent (S) is 9.0 or more and 12.5 or less. preferable.
It is presumed that the good affinity of the high boiling point solvent (SH) for the silica particles (B) has some kind of positive effect on the leveling of the coating film surface.

Solvent (S) preferably comprises one or more low boiling solvents (SL) having a boiling point of less than 170° C. at atmospheric pressure. When using a low boiling point solvent (SL) together with the high boiling point solvent (SH), when removing the solvent (S) from the coating film made of the cured film forming composition, the low boiling point solvent (SL) and the high boiling point solvent (SH) volatilize sequentially. Therefore, the solvent (S) does not rapidly volatilize from the coating film. As a result, it is easy to form a cured film while preventing defects such as unevenness and roughness on the surface of the cured film.

In addition, the low boiling point solvent (SL) includes one or more first low boiling point solvents (SL1) having a boiling point of 80° C. or more and less than 130° C. under atmospheric pressure, and C. and one or more second low boiling solvents (SL2) that are less than .degree.
When the low boiling point solvent (SL) contains two or more solvents with different boiling points, it is easier to form a cured film while preventing defects such as unevenness and roughness on the surface of the cured film.

Specific examples of high-boiling solvents (SH) include benzyl alcohol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether (butyl carbitol), triethylene glycol monomethyl ether, Triethylene glycol monoethyl ether, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether (DPM), dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether , N-methyl-2-pyrrolidone, 1,4-butanediol diacetate, diethylene glycol mono-n-butyl ether acetate, 1,6-hexanediol diacetate, ε-caprolactone, 1,3-butylene glycol diacetate, diethylene glycol mono Ethyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol methyl-n-butyl ether, γ-butyrolactone, dipropylene glycol methyl-n-propyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether acetate, and propylene glycol diacetate. mentioned.
The solvent (S) may contain a combination of two or more of these high boiling point solvents (SH).

Among the high boiling point solvents (SH) mentioned above, benzyl alcohol, diethylene glycol mono-n-butyl ether (butylcarbyl ether), and Toll), dipropylene glycol monomethyl ether (DPM), 1,4-butanediol diacetate, diethylene glycol mono-n-butyl ether acetate, 1,6-hexanediol diacetate, ε-caprolactone, 1,3-butylene glycol diacetate , diethylene glycol monoethyl ether acetate, dipropylene glycol methyl ether acetate, diethylene glycol methyl-n-butyl ether, γ-butyrolactone, dipropylene glycol methyl-n-propyl ether, 3-methoxybutyl acetate, ethylene glycol monobutyl ether acetate, and propylene glycol. Diacetate is preferred.

Suitable specific examples of the first low boiling point solvent (SL1) having a boiling point of 80° C. or more and less than 130° C. under atmospheric pressure include ethylene glycol monomethyl ether, propylene glycol monomethyl ether (PGME), n-propyl acetate, and acetic acid. isopropyl, isobutyl acetate, ethyl butyrate, n-butyl acetate, methyl ethyl ketone, and the like.
The solvent (S) may contain a combination of two or more of these first low boiling point solvents (SL1).

Preferable specific examples of the second low boiling point solvent (SL2) having a boiling point of 130° C. or more and less than 170° C. under atmospheric pressure include ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, and propylene glycol monoethyl ether. , propylene glycol mono-n-propyl ether, 3-methoxybutanol, diethylene glycol dimethyl ether (diglyme), ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, n-pentyl formate, isopentyl acetate, propionic acid n-butyl, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, 3-heptanone, N,N-dimethylformamide, N,N-dimethylacetamide, 2 -heptanone, cyclopentanone, and cyclohexanone.
The solvent (S) may contain a combination of two or more of these second low boiling point solvents (SL2).

The amount of the solvent (S) used in the cured film-forming composition is not particularly limited as long as the object of the present invention is not impaired. The amount of the solvent (S) used is appropriately determined in consideration of the film thickness of the cured film to be formed, etc. so that the viscosity of the composition for forming a cured film is an appropriate viscosity according to the coating method. .

Typically, the solid content concentration of the cured film-forming composition is 1% by mass or more and 50% by mass or less, preferably 2% by mass or more and 30% by mass or less, more preferably 3% by mass or more and 20% by mass or less. A solvent (S) is used for
When the coating method is slit coating, the solid content concentration of the composition for forming a cured film is 1% by mass or more and 15% by mass or less, preferably 2% by mass or more and 12% by mass or less, more preferably 3% by mass or more and 10% by mass. Solvent (S) is used as follows.

The content of the high-boiling point solvent (SH) in the solvent (S) is not particularly limited as long as the object of the present invention is not impaired. The content of the high-boiling solvent (SH) is preferably 2% by mass or more and 60% by mass or less, more preferably 2% by mass or more and 50% by mass or less, and 3% by mass or more and 30% by mass, relative to the mass of the solvent (S). % or less is more preferable, and 5% by mass or more and 25% by mass or less is particularly preferable.
The content of the low boiling point solvent (SL) in the solvent (S) is preferably 40% by mass or more and 98% by mass or less, more preferably 50% by mass or more and 98% by mass or less, relative to the mass of the solvent (S). 70% by mass or more and 97% by mass or less is more preferable, and 75% by mass or more and 95% by mass or less is particularly preferable.

When the low boiling point solvent (SL) contains the first low boiling point solvent (SL1) and the second low boiling point solvent (SL2), the content ratio of both in the low boiling point solvent (SL) is not particularly limited.
In this case, the content of the first low boiling point solvent (SL1) in the low boiling point solvent (SL) is preferably 20% by mass or more and 90% by mass or less, more preferably 30% by mass or more and 90% by mass or less, and 40% by mass. % or more and 80 mass % or less is more preferable.

<Other ingredients>
The cured film-forming fat composition may contain various additives as necessary. Additives include adhesion promoters, antioxidants, dispersants, aggregation inhibitors, antifoaming agents, and the like.

A composition for forming a cured film is produced by uniformly mixing each component described above in a desired composition.

When the cured film-forming composition described above is used, a cured film having a refractive index of 1.30 or less is preferably formed under the following cured film-forming condition 1.
<Cured film formation condition 1>
A slit coater is used to apply the cured film-forming composition onto a 6-inch silicon substrate at a coating speed (gantry speed) of 100 mm/sec to form a coating film having a size of 10 cm×10 cm and a thickness of 1000 nm.
After the formed coating film is placed under a reduced pressure condition of 20 Pa for 10 seconds, the glass substrate is placed on a hot plate and the coating film is heated at 100° C. for 2 minutes. Next, the glass substrate is heated to 230° C., and the coating film is heated at the same temperature for 20 minutes.

Further, when the cured film-forming composition described above is used, a cured film having a haze value of 1% or less is preferably formed under the following cured film-forming condition 2.
<Cured film formation condition 2>
The composition for forming a cured film is applied onto a glass substrate having a size of 680 mm×880 mm using a slit coater at a coating speed (gantry speed) of 180 mm/sec to form a coating film having a thickness of 1000 nm.
After the formed coating film is placed under a reduced pressure condition of 20 Pa for 10 seconds, the glass substrate is placed on a hot plate and the coating film is heated at 100° C. for 2 minutes. Next, the glass substrate is heated to 230° C., and the coating film is heated at the same temperature for 20 minutes.

By using the cured film-forming composition described above, it is possible to form a cured film having a low refractive index and free from defects on the surface. Such a cured film is suitably used for various applications such as a low refractive index film for covering microlenses for image sensors, and a low refractive index film for antireflection in liquid crystal displays, organic EL devices and the like.

<<Method of Forming Cured Film>>
The method for forming a cured film is
Formation of a coating film by applying the above cured film-forming composition onto a substrate;
Curing of the coating film by heating,
A method comprising:

In the formation of the coating film, slit coating, dip coating, spin coating, spray coating, screen printing coating, and the like are preferably used as the coating method. Among these methods, slit coating is preferable in that a uniform film can be formed in the plane of a panel-sized rectangular substrate.
When slit coating is performed, it is preferable to perform coating at a coating speed of 120 mm/sec or more in terms of manufacturing a substrate having a cured film at a high throughput.

As described above, when the composition containing the epoxy compound (A) and the hollow silica (B) is applied under the above conditions to form a cured film, the surface may have haze unevenness, streak unevenness, and pin marks. problems are likely to occur.
However, when the composition for forming a cured film described above is used, even if the coating film is formed by slit coating or the like, the cured film can be formed while suppressing defects on the surface.

The film thickness of the coating film is not particularly limited, and is preferably 50 nm or more and 5000 nm or less, and particularly preferably 100 nm or more and 2000 nm or less.

The coating film thus formed is then cured by heating.
When heating the coating film, it is preferable to once place the coating film under reduced pressure conditions. At least part of the solvent (S) in the coating film is removed by placing the coating film under reduced pressure conditions.
The temperature of the depressurized atmosphere is, for example, 0° C. or higher and 50° C. or lower, preferably 10° C. or higher and 30° C. or lower, near room temperature.
The degree of vacuum of the depressurized atmosphere is not particularly limited, but is, for example, 1 Pa or more and 300 Pa or less, preferably 10 Pa or more and 200 Pa or less.
By gently removing the solvent (S) from the coating film under the reduced pressure conditions described above, it is easy to form a cured film while suppressing defects on the surface.

The coating film formed as described above is optionally placed under reduced pressure conditions and then cured by heating. The heating conditions are not particularly limited as long as the curing of the coating film progresses satisfactorily.
The heating of the coating film is divided into, for example, preheating at a temperature in the range of about 60° C. or higher and 150° C. or lower, and main heating at a temperature in the range of about 150° C. or higher and 250° C. or lower, which is performed after the preheating. preferably done.
Although the preheating time is not particularly limited, it is typically 30 seconds or more and 10 minutes or less, preferably 1 minute or more and 5 minutes or less.
The main heating time is not particularly limited, but is typically 5 minutes or more and 60 minutes or less, preferably 10 minutes or more and 30 minutes or less.

By the method described above, it is possible to form a good cured film while suppressing surface defects such as haze unevenness, streak unevenness, and pin marks.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. The scope of the invention is not limited to these examples.

[Examples 1 to 14 and Comparative Examples 1 to 4]
In the examples and comparative examples, the following A-1 and A-2 were used as the epoxy compound (A) (component (A)).
A-1: Acrylic copolymer A comprising 42% by mass of units derived from glycidyl methacrylate, 42% by mass of units derived from 3,4-epoxycyclohexylmethyl methacrylate, and 16% by mass of units derived from methacrylic acid -2: Acrylic polymer composed of 80% by mass of units derived from glycidyl methacrylate and 20% by mass of units derived from 4-hydroxyphenyl methacrylate

In the examples and comparative examples, hollow silica particles having a volume average particle size of 60 nm were used as the hollow silica (B) (component (B)).

In the examples and comparative examples, the following C-1 to C-4 were used as the surfactant (C) (component (C)).
C-1: fluorine-based surfactant (PF-656, manufactured by OMNOVA) molecular weight 1500
C-2: Siloxane-based surfactant (polyester-modified polydimethylsiloxane, BYK-310 manufactured by BYK-Chemie) molecular weight 4000
C-3: Siloxane-based surfactant (Granol 440, manufactured by Kyoeisha Chemical Co., Ltd.) molecular weight 5300
C-4: fluorine-based surfactant (APX-4082B, manufactured by Kyoeisha Chemical Co., Ltd.) molecular weight 20000

For Examples and Comparative Examples, SL1-1 below as the first low boiling point solvent (SL1), SL2-1 and SL2-2 below as the second low boiling point solvent (SL2), and high boiling point solvent (SH) The following SH-1, SH-2 and SH-3 were used.
SL1-1: propylene glycol monomethyl ether SL2-1: 3-methoxybutanol SL2-2: propylene glycol monomethyl ether acetate SH-1: benzyl alcohol SH-2: dipropylene glycol monomethyl ether SH-3: diethylene glycol mono-n-butyl ether (butyl carbitol)
SH-4: propylene glycol diacetate

Epoxy compound (A) and hollow silica (B) in the amounts (parts by mass) shown in Tables 1 to 3, respectively, and surfactants (C) in the types and amounts (parts by mass) shown in Tables 1 to 3 ) were dissolved and dispersed in the solvent (S) so that the solid content concentrations shown in Tables 1 to 3 were obtained, to prepare cured film-forming compositions of Examples and Comparative Examples. As the solvent (S), a mixed solvent having the composition shown in Tables 1 to 3 was used.

Using each cured film-forming composition thus obtained, the occurrence of unevenness and pin marks in the cured film was evaluated by the following methods.
Using a slit coater, the composition for forming a cured film was applied onto a glass substrate having a size of 680 mm×880 mm at a coating speed (gantry speed) of 180 mm/sec to form a coating film having a thickness of 1000 nm.
After the formed coating film was placed under a reduced pressure condition of 20 Pa for 10 seconds, the glass substrate was placed on a hot plate and the coating film was heated at 100° C. for 2 minutes. Next, the glass substrate was transferred onto a hot plate at 230° C., and the coating film was heated for 20 minutes.
The surface of the formed coating film was observed with a microscope, and when unevenness such as haze unevenness or streak unevenness was observed, the unevenness was evaluated as x. On the other hand, when no unevenness was observed, the unevenness was evaluated as ◯.
In addition, when a pin trace was observed by microscopic observation, the pin trace was evaluated as x. On the other hand, when pin traces were not observed, the pin traces were evaluated as ◯.

A cured film was formed under the above cured film forming condition 1, and the refractive index of the formed cured film was measured. Tables 1 to 3 show the measurement results of the refractive index.

In addition, a cured film was formed under the above cured film forming condition 2, and the haze value of the formed cured film was measured. The haze values of the cured film-forming compositions of Comparative Examples 1, 2, and 4 were not measured.
A haze value of 1% or less was evaluated as ◯, and a haze value of more than 1% was evaluated as x. Evaluation results are shown in Tables 1 to 3.

From Tables 1 and 2, the epoxy compound (A), the hollow silica (B), and the solvent (S) are included, and the surfactant (C) is included. When using the cured film-forming composition of the example containing one or more high boiling point solvents (SH) having a boiling point of 170 ° C. or higher, good curing is performed while suppressing the occurrence of unevenness and pin marks on the surface. It can be seen that a film can be formed.
On the other hand, from Table 3, when using the cured film-forming composition of the comparative example that does not contain a high boiling point solvent (SH) or a surfactant (C), at least one of unevenness and pin marks occurs on the surface of the cured film. I know it's easy.

Claims (17)

Epoxy compound (A), hollow silica (B), surfactant (C) and solvent (S),
The epoxy compound (A) is a polymer having an epoxy group,
The content of units derived from a (meth)acrylic acid ester having an epoxy group in the polymer having an epoxy group is 80% by mass or more,
A composition for forming a cured film, wherein the solvent (S) contains one or more high-boiling solvents (SH) having a boiling point of 170° C. or higher under atmospheric pressure. 2. The composition for forming a cured film according to claim 1, wherein the high boiling point solvent (SH) has a boiling point of 250[deg.] C. or less under atmospheric pressure. 3. The composition for forming a cured film according to claim 1, which is applied to a substrate by slit coating to give a cured film. 4. The composition for forming a cured film according to claim 3, which is used for slit coating at a coating speed of 120 mm/sec or higher. The composition for forming a cured film according to any one of claims 1 to 4, wherein the solvent (S) contains one or more low boiling point solvents (SL) having a boiling point of less than 170°C under atmospheric pressure. thing. The low boiling point solvent (SL) comprises one or more first low boiling point solvents (SL1) having a boiling point of 80° C. or more and less than 130° C. under atmospheric pressure, and a first low boiling point solvent (SL1) having a boiling point of 130° C. or more and 170° C. under atmospheric pressure. 6. The composition for forming a cured film according to claim 5, comprising one or more second low boiling point solvents (SL2) that are less than . The composition for forming a cured film according to any one of claims 1 to 6, wherein the one or more high boiling point solvents (SH) have an SP value of 9.0 or more and 12.5 or less. The composition for forming a cured film according to any one of claims 1 to 7, wherein the surfactant (C) has a molecular weight of 2000 or more. Any one of claims 1 to 8, wherein the epoxy compound (A) has one or more functional groups selected from the group consisting of a carboxy group, a carboxylic anhydride group, a phenolic hydroxyl group, and an amino group. The composition for forming a cured film according to . The composition for forming a cured film according to any one of claims 1 to 9, wherein the epoxy compound (A) is a copolymer of monomers having unsaturated double bonds. The composition for forming a cured film according to any one of claims 1 to 10, wherein the hollow silica (B) has a volume average particle size of 50 nm or more and 100 nm or less. The polymer having an epoxy group is an aliphatic (meth)acrylic acid ester having a chain aliphatic epoxy group, an aliphatic (meth)acrylic acid ester having an alicyclic epoxy group, and an unsaturated carboxylic acid. is a copolymer,
Any one of claims 1 to 11, wherein the content of the hollow silica (B) is 70% by mass or more with respect to the sum of the mass of the epoxy compound (A) and the mass of the hollow silica (B). The composition for forming a cured film according to item 1. The cured film-forming composition according to any one of claims 1 to 12, which gives a cured film having a haze value of 1% or less when a cured film is formed under the following cured film-forming condition 2.
<Cured film formation condition 2>
The composition for forming a cured film is applied onto a glass substrate having a size of 680 mm×880 mm using a slit coater at a coating speed (gantry speed) of 180 mm/sec to form a coating film having a thickness of 1000 nm.
After the formed coating film is placed under a reduced pressure condition of 20 Pa for 10 seconds, the glass substrate is placed on a hot plate and the coating film is heated at 100° C. for 2 minutes. Next, the glass substrate is heated to 230° C., and the coating film is heated at the same temperature for 20 minutes. Formation of a coating film by coating the cured film-forming composition according to any one of claims 1 to 13 on a substrate;
Curing the coating film by heating;
A method for forming a cured film, comprising: 15. The method of forming a cured film according to claim 14, comprising removing at least part of said solvent (S) contained in said coating film by placing said coating film under reduced pressure conditions before said curing. 16. The method of forming a cured film according to claim 14 or 15, wherein the coating film is formed by a slit coating method. 17. The method of forming a cured film according to claim 16, wherein the coating speed in forming the coating film by slit coating is 120 mm/sec or more.