Photosensitive composition for forming optical member, method for producing cured product, method for producing microlens, method for producing microlens pattern, and microlens

Abstract

To provide a photosensitive composition for optical member formation which enables formation of an optical member such as a microlens having high light transmittance, a cured product production method using the photosensitive composition for optical member formation, a microlens manufacturing method using the photosensitive composition for optical member formation, a microlens pattern manufacturing method using the photosensitive composition for optical member formation, and a microlens.SOLUTION: A photosensitive composition contains a photo cationic curing agent (A), an acrylic resin (B), and a crosslinking agent (C) not corresponding to the acrylic resin (B), in which the photo cationic curing agent (A) is an onium salt including an anion part having a specific structure, and the acrylic resin (B) is an acrylic resin having a constitutional unit (b1) having a cationic polymerization group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photosensitive composition for forming an optical member, a method for producing a cured product using the photosensitive composition for forming an optical member, a method for producing a microlens, a method for producing a microlens pattern, and a microlens. [Background technology]

[0002] 2. Description of the Related Art Microlenses (hereinafter referred to as "microlenses") are used as optical members in image display elements such as OLEDs, and solid-state imaging elements such as charge coupled device (CCD) image sensors and complementary metal-oxide semiconductor (CMOS) image sensors.

[0003] The microlens is formed, for example, by curing a curable composition containing a curable resin. As the curable composition, for example, a resin composition for microlenses that contains a copolymer containing a structural unit containing an epoxy group and a structural unit containing a biphenylyl group, and a thermal acid generator has been disclosed (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2015 / 122109 Summary of the Invention [Problem to be solved by the invention]

[0005] It is desirable for a microlens to have excellent optical properties, that is, a high light transmittance. However, microlenses formed using conventional curable compositions such as those described in Patent Document 1 have a problem in that they have insufficient light transmittance.

[0006] The present invention has been made in consideration of the above problems, and has an object to provide a photosensitive composition for forming optical components, which can form optical components such as microlenses having high light transmittance, a method for producing a cured product using the above-mentioned photosensitive composition for forming optical components, a method for producing a microlens using the above-mentioned photosensitive composition for forming optical components, a method for producing a microlens pattern using the above-mentioned photosensitive composition for forming optical components, and a microlens. [Means for solving the problem]

[0007] The present inventors have found that the above-mentioned problems can be solved by a photosensitive composition comprising a cationic photocuring agent (A), an acrylic resin (B), and a crosslinking agent (C) not corresponding to the acrylic resin (B), in which the cationic photocuring agent (A) is an onium salt containing an anion moiety of a specific structure, and the acrylic resin (B) is an acrylic resin having a structural unit (b1) having a cationic polymerization group, and have completed the present invention.

[0008] The first aspect of the present invention includes a photocationic curing agent (A), an acrylic resin (B), and a crosslinking agent (C) that does not fall under the category of the acrylic resin (B), The photocationic curing agent (A) is an onium salt containing an anion moiety represented by the following formula (a1): The photosensitive composition for forming optical members is such that the acrylic resin (B) is an acrylic resin having at least a structural unit (b1) having a cationic polymerization group. [ka] (In formula (a1), R 1a ~R 4a each independently represents a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent; R 1a ~R 4a At least one of the groups represents an aromatic hydrocarbon group which may have a substituent.

[0009] A second aspect of the present invention is a method for producing a photosensitive composition for forming an optical member according to the first aspect, comprising: an exposure step of exposing the coating film obtained by the coating film forming step; The present invention relates to a method for producing a cured product having the above structure.

[0010] A third aspect of the present invention provides a method for producing a cured product comprising the steps of: providing a mask having substantially the same shape as a lens to be formed on the cured product obtained by the method for producing a cured product according to the second aspect; This is a method for manufacturing a microlens, which includes a lens forming step in which, after the mask forming step, the mask and the cured product are dry-etched to form a microlens to which the shape of the mask is transferred.

[0011] A fourth aspect of the present invention is a method for producing a photosensitive composition for forming an optical member according to the first aspect, comprising: an exposure step of position-selectively exposing the coating film obtained by the coating film forming step; a developing step of developing the coating film exposed in the exposure step to obtain a patterned cured product; The present invention relates to a method for manufacturing a microlens pattern having the above structure.

[0012] A fifth aspect of the present invention is a microlens made of a cured product of the photosensitive composition for forming an optical member according to the first aspect. Effect of the Invention

[0013] According to the present invention, it is possible to provide a photosensitive composition for forming optical members capable of forming optical members such as microlenses having high light transmittance, a method for producing a cured product using the above-mentioned photosensitive composition for forming optical members, a method for producing a microlens using the above-mentioned photosensitive composition for forming optical members, a method for producing a microlens pattern using the above-mentioned photosensitive composition for forming optical members, and a microlens. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] ≪Photosensitive composition for forming optical members≫ The photosensitive composition for forming optical members (hereinafter, simply referred to as "photosensitive composition") contains a photocationic curing agent (A), an acrylic resin (B), and a crosslinking agent (C) that does not fall under the category of the acrylic resin (B). The photocationic curing agent (A) is an onium salt containing an anion moiety represented by the following formula (a1). The acrylic resin (B) is an acrylic resin having at least a structural unit (b1) having a cationic polymerization group. [ka] (In formula (a1), R 1a ~R 4a each independently represents a hydrocarbon group which may have a substituent or a heterocyclic group which may have a substituent; R 1a ~R 4a At least one of the groups represents an aromatic hydrocarbon group which may have a substituent.

[0015] The optical member formed by the photosensitive composition for forming an optical member is a lens that requires high light transmittance, particularly a microlens used in an image display device such as an OLED, or a solid-state imaging device such as a CCD image sensor or a CMOS image sensor. For example, in the case of a circular shape, the diameter of the microlens can be 0.2 μm to 10 μm, or 0.2 μm to 5 μm. In addition, in the case of a rectangular shape, a microlens with one side of 0.2 μm to 10 μm or 0.2 μm to 5 μm can be formed.

[0016] The photosensitive composition can form a cured product with high light transmittance, as shown in the examples described later. The cured product formed using the photosensitive composition can have a light transmittance of, for example, 95% or more, preferably 98% or more, and more preferably 99% or more at a wavelength of 400 nm. The cured product can be used as an optical member because of its high light transmittance. On the other hand, when the photocationic curing agent is not an onium salt containing an anion portion represented by the above formula (a1) (for example, when it is not an onium salt, or when the anion portion contains antimony or phosphorus instead of gallium), or when the resin is not an acrylic resin having a structural unit (b1) having a cationic polymerization group (for example, when it is a phenolic resin or a polyhydroxystyrene resin), the light transmittance is poor. By exposing and etching the photosensitive composition, a microlens having high light transmittance can be produced. By selectively exposing and developing the photosensitive composition, a microlens pattern having high light transmittance can be produced. Furthermore, the above photosensitive composition allows the production of microlenses at low temperatures (for example, 100° C. or lower), and is therefore suitable as a microlens for devices such as OLEDs that are desirably produced at low temperatures.

[0017] The essential and optional components contained in the photosensitive composition will be described below.

[0018] <Photocationic curing agent (A)> The photosensitive composition contains a cationic photocuring agent (A) as a component for curing the acrylic resin (B). The cationic photocuring agent (A) generates an acid upon exposure to light, and the generated acid causes the cationic polymerizable groups of the acrylic resin (B) to react with each other or with the crosslinking agent (C), thereby obtaining a cured product of the photosensitive composition.

[0019] The photocationic curing agent (A) is an onium salt consisting of a cation moiety and an anion moiety represented by the above formula (a1).

[0020] R in formula (a1) 1a ~R4a The number of carbon atoms in the hydrocarbon group or heterocyclic group as the substituent is not particularly limited, but is preferably 1 or more and 50 or less, more preferably 1 or more and 30 or less, and particularly preferably 1 or more and 20 or less. R 1a ~R 4a Specific examples of the hydrocarbon group as the alkyl group include a linear or branched alkyl group, a linear or branched alkenyl group, a linear or branched alkynyl group, an aromatic hydrocarbon group, an alicyclic hydrocarbon group, and an aralkyl group. As mentioned above, R 1a ~R 4a At least one of R is an aromatic group which may have a substituent. 1a ~R 4a More preferably, three or more of R are aromatic groups which may have a substituent. 1a ~R 4a It is particularly preferred that all of the radicals are aromatic groups which may have a substituent.

[0021] R 1a ~R 4a Examples of the substituent that the hydrocarbon group or heterocyclic group may have as the substituent include a halogenated alkyl group having from 1 to 18 carbon atoms, a halogenated aliphatic cyclic group having from 3 to 18 carbon atoms, a nitro group, a hydroxyl group, a cyano group, an alkoxy group having from 1 to 18 carbon atoms, an aryloxy group having from 6 to 14 carbon atoms, an aliphatic acyl group having from 2 to 19 carbon atoms, an aromatic acyl group having from 7 to 15 carbon atoms, an aliphatic acyloxy group having from 2 to 19 carbon atoms, an aromatic acyloxy group having from 7 to 15 carbon atoms, an alkylthio group having from 1 to 18 carbon atoms, an arylthio group having from 6 to 14 carbon atoms, an amino group in which one or two hydrogen atoms bonded to the nitrogen atom may be substituted with a hydrocarbon group having from 1 to 18 carbon atoms, and a halogen atom. R 1a ~R 4aWhen the hydrocarbon group as represented by is an aromatic hydrocarbon group, the aromatic hydrocarbon group may be substituted with one or more substituents selected from the group consisting of an alkyl group having from 1 to 18 carbon atoms, an alkenyl group having from 2 to 18 carbon atoms, and an alkynyl group having from 2 to 18 carbon atoms.

[0022] R 1a ~R 4a When the hydrocarbon group as has a substituent, the number of the substituents is not particularly limited and may be 1 or more than 2. When the number of the substituents is more than one, the multiple substituents may be the same or different.

[0023] R 1a ~R 4a When is an alkyl group, preferred specific examples include straight-chain alkyl groups such as a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-octyl group, an n-nonyl group, an n-decyl group, an n-undecyl group, an n-dodecyl group, an n-tridecyl group, an n-tetradecyl group, an n-pentadecyl group, an n-hexadecyl group, an n-heptadecyl group, an n-octadecyl group, an n-nonadecyl group, and an n-icosyl group; and branched-chain alkyl groups such as an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, a 2-ethylhexyl group, and a 1,1,3,3-tetramethylbutyl group.

[0024] R 1a ~R 4a When is an alkenyl group or an alkynyl group, preferred examples include alkenyl groups and alkynyl groups corresponding to the above groups preferred as the alkyl group.

[0025] R 1a ~R 4a When is an aromatic hydrocarbon group, preferred examples include a phenyl group, an α-naphthyl group, a β-naphthyl group, a biphenyl-4-yl group, a biphenyl-3-yl group, a biphenyl-2-yl group, an anthryl group, and a phenanthryl group.

[0026] R 1a ~R 4a Preferred examples of the alicyclic hydrocarbon group include cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cyclopentyl group, a cyclooctyl group, a cyclononyl group, and a cyclodecyl group; and bridged aliphatic cyclic hydrocarbon groups such as a norbornyl group, an adamantyl group, a tricyclodecyl group, and a pinanyl group.

[0027] R 1a ~R 4a When is an aralkyl group, preferred examples thereof include a benzyl group, a phenethyl group, an α-naphthylmethyl group, a β-naphthylmethyl group, an α-naphthylethyl group, and a β-naphthylethyl group.

[0028] R 1a ~R 4a Preferred examples of the heterocyclic group include a thienyl group, a furanyl group, a selenophenyl group, a pyranyl group, a pyrrolyl group, an oxazolyl group, a thiazolyl group, a pyridyl group, a pyrimidyl group, a pyrazinyl group, an indolyl group, a benzofuranyl group, a benzothienyl group, a quinolyl group, an isoquinolyl group, a quinoxalinyl group, a quinazolinyl group, a carbazolyl group, an acridinyl group, a phenothiazinyl group, a phenazinyl group, a xanthenyl group, a thianthrenyl group, a phenoxazinyl group, a phenoxathiinyl group, a chromanyl group, an isochromanyl group, a dibenzothienyl group, a xanthonyl group, a thioxanthonyl group, and a dibenzofuranyl group.

[0029] R 1a ~R 4aWhen the substituent that the hydrocarbon group or heterocyclic group may have as the substituent is a halogenated alkyl group, preferred examples of the halogenated alkyl group include linear halogenated alkyl groups such as a trifluoromethyl group, a trichloromethyl group, a pentafluoroethyl group, a 2,2,2-trichloroethyl group, a 2,2,2-trifluoroethyl group, a 1,1-difluoroethyl group, a heptafluoro-n-propyl group, a 1,1-difluoro-n-propyl group, a 3,3,3-trifluoro-n-propyl group, a nonafluoro-n-butyl group, a 3,3,4,4,4-pentafluoro-n-butyl group, a perfluoro-n-pentyl group, and a perfluoro-n-octyl group; and branched halogenated alkyl groups such as a hexafluoroisopropyl group, a hexachloroisopropyl group, a hexafluoroisobutyl group, and a nonafluoro-tert-butyl group.

[0030] R 1a ~R 4a When the hydrocarbon group as the substituent group or the substituent that the heterocyclic group may have is a halogenated aliphatic cyclic group, preferred examples of the halogenated aliphatic cyclic group include a pentafluorocyclopropyl group, a nonafluorocyclobutyl group, a perfluorocyclopentyl group, a perfluorocyclohexyl group, and a perfluoroadamantyl group.

[0031] R 1a ~R 4aWhen the hydrocarbon group as the substituent or the substituent that the heterocyclic group may have is an alkoxy group, preferred examples of the alkoxy group include straight-chain alkoxy groups such as a methoxy group, an ethoxy group, an n-propyloxy group, an n-butyloxy group, an n-pentyloxy group, an n-hexyloxy group, an n-octyloxy group, an n-nonyloxy group, an n-decyloxy group, an n-undecyloxy group, an n-dodecyloxy group, an n-tridecyloxy group, an n-tetradecyloxy group, an n-pentadecyloxy group, an n-hexadecyloxy group, an n-heptadecyloxy group, and an n-octadecyloxy group; and branched-chain alkoxy groups such as an isopropyloxy group, an isobutyloxy group, a sec-butyloxy group, a tert-butyloxy group, an isopentyloxy group, a neopentyloxy group, a tert-pentyloxy group, an isohexyloxy group, a 2-ethylhexyloxy group, and a 1,1,3,3-tetramethylbutyloxy group.

[0032] R 1a ~R 4a When the hydrocarbon group or the substituent that the heterocyclic group may have as the substituent is an aryloxy group, preferred examples of the aryloxy group include a phenoxy group, an α-naphthyloxy group, a β-naphthyloxy group, a biphenyl-4-yloxy group, a biphenyl-3-yloxy group, a biphenyl-2-yloxy group, an anthryloxy group, and a phenanthryloxy group.

[0033] R 1a ~R 4a When the hydrocarbon group as the substituent or the substituent that the heterocyclic group may have is an aliphatic acyl group, preferred examples of the aliphatic acyl group include an acetyl group, a propanoyl group, a butanoyl group, a pentanoyl group, a hexanoyl group, a heptanoyl group, and an octanoyl group.

[0034] R 1a ~R 4aWhen the hydrocarbon group as the substituent or the substituent that the heterocyclic group may have is an aromatic acyl group, preferred examples of the aromatic acyl group include a benzoyl group, an α-naphthoyl group, a β-naphthoyl group, a biphenyl-4-ylcarbonyl group, a biphenyl-3-ylcarbonyl group, a biphenyl-2-ylcarbonyl group, an anthrylcarbonyl group, and a phenanthrylcarbonyl group.

[0035] R 1a ~R 4a When the hydrocarbon group as the substituent group or the substituent that the heterocyclic group may have is an aliphatic acyloxy group, preferred examples of the aliphatic acyloxy group include an acetyloxy group, a propanoyloxy group, a butanoyloxy group, a pentanoyloxy group, a hexanoyloxy group, a heptanoyloxy group, and an octanoyloxy group.

[0036] R 1a ~R 4a When the hydrocarbon group as the substituent or the substituent that the heterocyclic group may have is an aromatic acyloxy group, preferred examples of the aromatic acyloxy group include a benzoyloxy group, an α-naphthoyloxy group, a β-naphthoyloxy group, a biphenyl-4-ylcarbonyloxy group, a biphenyl-3-ylcarbonyloxy group, a biphenyl-2-ylcarbonyloxy group, an anthrylcarbonyloxy group, and a phenanthrylcarbonyloxy group.

[0037] R 1a ~R 4a When the substituent that the hydrocarbon group or heterocyclic group as the above may have is an alkylthio group or an arylthio group, preferred examples of the alkylthio group or arylthio group include groups in which the oxygen atom in the above-mentioned groups suitable for the alkoxy group or aryloxy group is replaced with a sulfur atom.

[0038] R 1a ~R 4aWhen the hydrocarbon group as the substituent or the substituent that the heterocyclic group may have is an amino group optionally substituted with a hydrocarbon group, suitable examples of the amino group optionally substituted with a hydrocarbon group include an amino group, a methylamino group, an ethylamino group, an n-propylamino group, a dimethylamino group, a diethylamino group, a methylethylamino group, a di-n-propylamino group, and a piperidino group.

[0039] R 1a ~R 4a When the substituent that the hydrocarbon group or heterocyclic group as the substituent may have is a halogen atom, suitable examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0040] Specific preferred examples of the anion represented by formula (a1) explained above include tetrakis(4-nonafluorobiphenyl)gallate anion, tetrakis(1-heptafluoronaphthyl)gallate anion, tetrakis(pentafluorophenyl)gallate anion, tetrakis(3,4,5-trifluorophenyl)gallate anion, tetrakis(2-nonaphenylbiphenyl)gallate anion, tetrakis(2-heptafluoronaphthyl)gallate anion, tetrakis(7-nonafluoroanthryl)gallate anion, tetrakis(4'-(methoxy)octafluorobiphenyl)gallate anion, tetrakis(2,4,6-tris(trifluoromethyl)phenyl)gallate anion, tetrakis(3,5-bis(trifluoromethyl)phenyl)gallate anion, tetrakis(2,3-bis(pentafluorophenyl)gallate anion,

[0046] Examples of the anion include tetrakis(2-isopropoxy-hexafluoronaphthyl)gallate anion, tetrakis(9,10-bis(heptafluoropropyl)heptafluoroanthryl)gallate anion, tetrakis(9-nonafluorophenanthryl)gallate anion, tetrakis(4-[tri(isopropyl)silyl]-tetrafluorophenyl)gallate anion, tetrakis(9,10-bis(p-tolyl)-heptafluorophenanthryl)gallate anion, tetrakis(4-[dimethyl(t-butyl)silyl]-tetrafluorophenyl)gallate anion, monophenyltris(pentafluorophenyl)gallate anion, and monoperfluorobutyltris(pentafluorophenyl)gallate anion. More preferred examples of the anions include the following anions. [ka]

[0041] The cationic moiety of the photocationic curing agent (A) is preferably a cation represented by the following formula (a2). [ka] (In formula (a2), R 11a ~R 18aeach independently represents an alkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a hydroxy(poly)alkyleneoxy group, a cyano group, a nitro group, a halogen atom, or a hydrogen atom; R 19a ~R 24a each independently represents an alkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a hydroxy(poly)alkyleneoxy group, a cyano group, a nitro group, or a halogen atom; n1 to n4 each independently represent an integer of 0 or more and 1 or less, and when n1 to n4 each represent 0, they represent a direct bond between rings; m1 to m6 are R 19a ~R 24a m1, m4, and m6 each represent an integer of 0 or more and 4 or less, m2 and m5 each represent an integer of 0 or more and 3 or less, and m3 represents an integer of 0 or more and 5 or less.

[0042] In formula (a2), R 11a ~R 24a Among these, examples of the alkyl group include a linear alkyl group having 1 to 18 carbon atoms, a branched alkyl group having 1 to 18 carbon atoms, and a cycloalkyl group having 3 to 18 carbon atoms. Specific examples of the linear alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-octyl group, an n-decyl group, an n-dodecyl group, an n-tetradecyl group, an n-hexadecyl group, and an n-octadecyl group. Specific examples of the branched alkyl group include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, an isohexyl group, and an isooctadecyl group. Specific examples of the above cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a 4-decylcyclohexyl group.

[0043] In formula (a2), R 11a ~R 24aAmong these, examples of the aryl group include aryl groups having 6 to 12 carbon atoms. Specific examples of the aryl group include a phenyl group, a tolyl group, a dimethylphenyl group, a naphthyl group, and a biphenylyl group.

[0044] In formula (a2), R 11a ~R 24a Among these, the alkoxy group includes a straight-chain or branched-chain alkoxy group having 1 to 18 carbon atoms. Specific examples of the linear or branched alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, a hexyloxy group, a decyloxy group, a dodecyloxy group, and an octadecyloxy group.

[0045] In formula (a2), R 11a ~R 24a Among these, the aryloxy group includes an aryloxy group having 6 to 10 carbon atoms. Specific examples of the aryloxy group include a phenoxy group and a naphthyloxy group.

[0046] In formula (a2), R 11a ~R 24a Among these, examples of the hydroxy(poly)alkyleneoxy group include a hydroxy(poly)alkyleneoxy group represented by the formula (a2-1). HO(-AO) q - (a2-1) (AO represents an ethyleneoxy group and / or a propyleneoxy group, and q represents an integer of 1 or more and 5 or less.)

[0047] In formula (a2), R 11a ~R 24a Among these, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0048] In formula (a2), R 11a ~R 24aare each independent and therefore may be the same or different.

[0049] R 11a ~R 18a Among these, preferred are alkyl groups, alkoxy groups and a hydrogen atom, and particularly preferred is an alkyl group.

[0050] R 19a ~R 24a Among these, preferred are alkyl groups and alkoxy groups, and particularly preferred are alkyl groups.

[0051] Each of n1 to n4 represents an integer of 0 or more and 1 or less. When each of n1 to n4 is 0, it indicates a direct bond between rings. m1 to m6 are R 19a ~R 24a m1, m4, and m6 are integers of 0 to 4, m2 and m5 are integers of 0 to 3, and m3 is an integer of 0 to 5. It is preferable that n2 and n4 are 0, and it is particularly preferable that n1 and n3 are 1, n2 and n4 are 0, and m1 to m6 are 0.

[0052] In formula (a2), R 11a , R 12a , R 15a and R 16a is a methyl group, n1 and n3 are 1, n2 and n4 are 0, and m1 to m6 are 0. Sulfonium salts represented by the following formula are particularly preferred.

[0053] [ka]

[0054] The photosensitive composition may contain one type of cationic photocuring agent (A) or a combination of two or more types of cationic photocuring agents (A).

[0055] The content of the photocationic curing agent (A) in the photosensitive composition is, for example, 0.01 parts by mass or more and 20 parts by mass or less, preferably 0.1 parts by mass or more and 15 parts by mass or less, and more preferably 1 part by mass or more and 10 parts by mass or less, relative to 100 parts by mass in total of the acrylic resin (B) and the crosslinking agent (C).

[0056] <Acrylic resin (B)> The acrylic resin (B) is an acrylic resin that contains at least a structural unit (b1) having a cationic polymerization group.

[0057] The term "acrylic resin" refers to a resin containing 70 mol% or more of acrylic constituent units, which are constituent units derived from (meth)acrylic acid or (meth)acrylic acid derivatives. The acrylic resin is preferably a resin containing 80 mol% or more of the acrylic constituent units, more preferably a resin containing 90 mol% or more of the acrylic constituent units, and particularly preferably a resin containing 100 mol% of the acrylic constituent units. The "acrylic resin" may contain 30 mol% or less of constituent units derived from monomers other than (meth)acrylic acid and (meth)acrylic acid derivatives. In addition, in this specification, the term "(meth)acrylic acid derivative" refers to a compound having a (meth)acryloyloxy group. In this specification, "(meth)acrylic" means both "acrylic" and "methacrylic." "(meth)acryloyloxy" means both "acryloyloxy" and "methacryloyloxy."

[0058] The cationically polymerizable groups are groups that can undergo cationically polymerizable with each other and / or with the crosslinking agent (C) by the acid generated from the photocationic curing agent (A). Examples of the cationic polymerizable group include an epoxy group-containing group, an oxetanyl group-containing group, and an oxolanyl group-containing group, etc. The epoxy group-containing group is a group containing an epoxy group, the oxetanyl group-containing group is a group containing an oxetanyl group, and the oxolanyl group-containing group is a group containing an oxolanyl group.

[0059] An example of the structural unit (b1) having a cationic polymerization group is a structural unit represented by the following formula (b1-1). [ka] (In formula (b1-1), R 1b represents a hydrogen atom or a methyl group, R 2b represents a single bond or an alkylene group having 1 to 5 carbon atoms; R 3b represents an epoxy group-containing group, an oxetanyl group-containing group, or an oxolanyl group-containing group.

[0060] In formula (b1-1), R 1b is a hydrogen atom or a methyl group.

[0061] In formula (b1-1), R 2b R is a single bond or an alkylene group having 1 to 5 carbon atoms. The alkylene group may be linear or branched, and is preferably linear. 2b Specific examples of the alkylene group as the alkyl group include a methylene group, an ethane-1,2-diyl group, an ethane-1,1-diyl group, a propane-1,3-diyl group, a propane-1,2-diyl group, a butane-1,4-diyl group, and a pentane-1,5-diyl group. Of these groups, methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, and pentane-1,5-diyl are preferred, methylene, ethane-1,2-diyl, and propane-1,3-diyl are more preferred, and methylene is particularly preferred.

[0062] In formula (b1-1), R 3b is an epoxy group-containing group, an oxetanyl group-containing group, or an oxolanyl group-containing group. R 3b Examples include oxiran-2-yl, 3,4-epoxycyclohexyl, and 3,4-epoxytricyclo[5.2.1.0 2,6 ]Decan-1-yl, oxetan-3-yl, 3-ethyloxetan-3-yl, and oxolan-2-yl groups are preferred. In formula (b1-1), -R 2b -R 3b Examples of the group represented by the formula (I) include a glycidyl group (oxiran-2-ylmethyl group), a 3,4-epoxycyclohexylmethyl group, a 3,4-epoxytricyclo[5.2.1.0 2,6 ]Decan-1-yl, 3-ethyloxetan-3-ylmethyl, and oxolan-2-ylmethyl groups are preferred.

[0063] The amount of the structural unit (b1) having a cationic polymerization group in the acrylic resin (B) is not particularly limited as long as it does not impair the object of the present invention. The content of the structural unit (b1) having a cationic polymerization group in the acrylic resin (B) is preferably 20 mol% or more, more preferably 30 mol% or more and 90 mol% or less, and even more preferably 50 mol% or more and 80 mol% or less, based on the total structural units of the acrylic resin (B).

[0064] The acrylic resin (B) preferably contains a structural unit (b2) having an alkali-soluble group. By containing the structural unit (b2) having an alkali-soluble group, the acrylic resin (B) can become an alkali-soluble resin that dissolves in a basic solution (alkaline solution). Examples of the alkali-soluble group include a phenolic hydroxyl group and a carboxyl group.

[0065] An example of the structural unit (b2) having an alkali-soluble group is a structural unit represented by the following formula (b2-1). [ka] (In formula (b2-1), R 4b represents a hydrogen atom or a methyl group, R 5b represents an alkyl group having 1 to 5 carbon atoms, a represents an integer of 1 to 5, b represents an integer of 0 to 4, and a+b is 5 or less; R 5b If there are two or more R 5b may be different from each other or may be the same.)

[0066] In formula (b2-1), R4b is a hydrogen atom or a methyl group.

[0067] In formula (b2-1), R 5b is an alkyl group having 1 to 5 carbon atoms. 5b The alkyl group as R may be linear or branched. 5b Specific examples of the alkyl group as the aryl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a sec-pentyl group, a tert-pentyl group, and a pentan-3-yl group.

[0068] In formula (b2-1), R on the benzene ring 5b The number b is an integer of 0 to 4, and is preferably 0.

[0069] In formula (b2-1), a, which is the number of hydroxyl groups on the benzene ring, is an integer of 1 to 5. a is preferably 1 or 2, and more preferably 1, from the viewpoint of ease of availability and synthesis of the compound that gives the structural unit represented by formula (b2-1).

[0070] In formula (b2-1), at least one of the one or more hydroxyl groups is preferably bonded to the benzene ring at a para position relative to the position to which the group represented by -CO-O- is bonded.

[0071] The structural unit (b2) having an alkali-soluble group also includes a structural unit derived from (meth)acrylic acid.

[0072] The amount of the structural unit (b2) having an alkali-soluble group in the acrylic resin (B) is not particularly limited as long as it does not impair the object of the present invention. The content of the structural unit (b2) having an alkali-soluble group in the acrylic resin (B) is preferably 10 mol% or more, more preferably 10 mol% or more and 50 mol% or less, and even more preferably 20 mol% or more and 40 mol% or less, based on the total structural units of the acrylic resin (B).

[0073] The acrylic resin (B) may have a structural unit (b3) having a hydroxyalkyl group. Examples of the structural unit (b3) having a hydroxyalkyl group include the structural unit represented by the following formula (b3-1). [ka] In formula (b3-1), R 6b represents a hydrogen atom or a methyl group, R 7b represents an alkylene group.

[0074] In formula (b3-1), R 6b is a hydrogen atom or a methyl group.

[0075] In formula (b3-1), R 7b is an alkylene group. 7b The alkylene group as may be linear or branched.

[0076] R 7b The number of carbon atoms in the alkylene group represented by R is preferably 1 or more and 20 or less, more preferably 2 or more and 10 or less, and particularly preferably 2 or more and 6 or less. 7b Specific examples of the alkylene group as the alkylene group include a methylene group, an ethane-1,2-diyl group, an ethane-1.1-diyl group, a propane-1,3-diyl group, a propane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a nonane-1,9-diyl group, and a decane-1,10-diyl group. group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, octadecane-1,18-diyl group, nonadecane-1,19-diyl group, and icosane-1,20-diyl group. Among these, methylene group, ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, undecane-1,11-diyl group, dodecane-1,12-diyl group, tridecane-1,13-diyl group, tetradecane-1,14-diyl group, pentadecane-1,15-diyl group, hexadecane-1,16-diyl group, heptadecane-1,17-diyl group, octadecane-1, Preferred are 18-diyl, nonadecane-1,19-diyl, and icosane-1,20-diyl groups, more preferred are methylene, ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, nonane-1,9-diyl, and decane-1,10-diyl groups, and more preferred are ethane-1,2-diyl, propane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, and hexane-1,6-diyl groups.

[0077] The amount of the structural unit (b3) having a hydroxyalkyl group in the acrylic resin (B) is not particularly limited as long as it does not impair the object of the present invention. When the acrylic resin (B) has a structural unit (b3) having a hydroxyalkyl group, the content of the structural unit (b3) having a hydroxyalkyl group in the acrylic resin (B) is preferably 1 mol% or more and 20 mol% or less, more preferably 5 mol% or more and 15 mol% or less, based on the total structural units of the acrylic resin (B).

[0078] The acrylic resin (B) may have a structural unit (b4) derived from styrene. The structural unit derived from styrene is a structural unit derived from at least one selected from styrene and monomers in which the hydrogen atom bonded to the α-position of styrene is substituted with another substituent such as a halogen atom, an alkyl group, or a halogenated alkyl group.

[0079] The amount of the structural unit (b4) derived from styrene in the acrylic resin (B) is not particularly limited as long as it does not impair the object of the present invention. When the acrylic resin (B) has the structural unit (b4) derived from styrene, the content of the structural unit (b4) derived from styrene in the acrylic resin (B) is preferably 1 mol% or more and 20 mol% or less, more preferably 5 mol% or more and 15 mol% or less, based on the total structural units of the acrylic resin (B).

[0080] The mass average molecular weight of the acrylic resin (B) is preferably 3000 or more, more preferably 3500 to 10000, and particularly preferably 4000 to 8000. The mass average molecular weight is a molecular weight measured by GPC in terms of polystyrene. When the mass average molecular weight of the resin is relatively large, it is easy to form a cured product having excellent solvent resistance and thermal decomposition resistance.

[0081] The photosensitive composition may contain one type of acrylic resin (B) or a combination of two or more types of acrylic resins (B).

[0082] The content of the acrylic resin (B) in the photosensitive composition is, for example, 50 parts by mass or more and 95 parts by mass or less, preferably 70 parts by mass or more and 90 parts by mass or less, and more preferably 75 parts by mass or more and 85 parts by mass or less, relative to 100 parts by mass of the solid content of the photosensitive composition. In this specification, the solid content is the mass of the photosensitive composition excluding the mass of the solvent.

[0083] <Crosslinking agent (C)> The crosslinking agent (C) is not a type of acrylic resin (B). The crosslinking agent (C) crosslinks the acrylic resin (B) by the action of the acid generated from the photocationic curing agent (A) upon exposure to light.

[0084] The crosslinking agent (C) is not particularly limited, and may be appropriately selected from known crosslinking agents. Examples of the crosslinking agent (C) include melamine compounds. The melamine-based compound may be alkoxymethylated melamine, and specific examples thereof include methoxymethylated melamine, propoxymethylated melamine, and butoxymethylated melamine.

[0085] The photosensitive composition may contain one type of crosslinking agent (C) or a combination of two or more types of crosslinking agents (C).

[0086] The content of the crosslinking agent (C) in the photosensitive composition is, for example, 5 parts by mass or more and 40 parts by mass or less, preferably 10 parts by mass or more and 30 parts by mass or less, and more preferably 15 parts by mass or more and 25 parts by mass or less, relative to 100 parts by mass of the acrylic resin (B).

[0087] <Solvent> The photosensitive composition may contain a solvent. The type of the solvent is not particularly limited as long as it does not impair the object of the present invention. The photosensitive composition may contain one type of solvent or a combination of two or more types of solvents.

[0088] Suitable examples of the solvent include monoalkyl ethers of glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monopropyl ether, and propylene glycol monobutyl ether; ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, propylene glycol monopropyl ether acetate, and propylene glycol monobutyl ether. monoalkyl ether acetates of glycols such as acetate; aromatic solvents such as toluene and xylene; ketones such as acetone, methyl ethyl ketone, 2-heptanone, cyclopentanone, and cyclohexanone; and esters such as ethyl acetate, butyl acetate, ethyl ethoxyacetate, ethyl hydroxyacetate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, methyl 2-hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate, methyl pyruvate, ethyl lactate, butyl lactate, and γ-butyrolactone.

[0089] Among these solvents, from the viewpoint of the leveling properties of the coating film when the photosensitive composition is applied, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, 2-heptanone, cyclopentanone, cyclohexanone, ethyl lactate, and butyl lactate are preferred, and propylene glycol monomethyl ether acetate, 2-heptanone, cyclopentanone, and cyclohexanone are more preferred.

[0090] The amount of the solvent used in the photosensitive composition is not particularly limited, and is appropriately determined taking into consideration the viscosity of the photosensitive composition and the like. The amount of the solvent used is preferably such that the solid content concentration in the photosensitive composition is 2% by mass or more, more preferably such that the solid content concentration is 3% by mass or more, and even more preferably such that the solid content concentration is 5% by mass or more. The amount of the solvent used is preferably such that the solid content concentration in the photosensitive composition is 50% by mass or less, more preferably such that the solid content concentration is 45% by mass or less, and even more preferably such that the solid content concentration is 40% by mass or less.

[0091] The photosensitive composition may further contain various additives within the scope of not impairing the object of the present invention. Examples of the additives include ultraviolet absorbers, plasticizers, antioxidants, light stabilizers, adhesion aids, fillers (e.g., fillers for increasing the refractive index, such as zirconium oxide fine particles), surfactants, etc.

[0092] <<Method for producing photosensitive composition>> The photosensitive composition can be produced by uniformly mixing the above-described components at a predetermined ratio. A mixing device that can be used to produce the photosensitive composition includes a two-roll or three-roll mixer. When the viscosity of the photosensitive composition is sufficiently low, the photosensitive composition may be filtered using a filter having an opening of a desired size, if necessary, to remove insoluble foreign matter.

[0093] <Production method of cured product> A method for producing a cured product of the above-mentioned photosensitive composition for forming optical members will be described below. The method for producing the cured product is as follows: a coating film forming step of coating the photosensitive composition for forming an optical member on a substrate to form a coating film; and an exposure step of exposing the coating film obtained in the coating film forming step.

[0094] The substrate is not particularly limited as long as it can be used as a substrate for forming an optical member such as a microlens. For example, when forming an OLED microlens, a substrate on which a coating film is formed may be a substrate on which a light-emitting layer is formed.

[0095] The method of applying the photosensitive composition onto the substrate is not particularly limited. For example, the photosensitive composition can be applied onto the substrate to a desired thickness using a contact transfer type application device such as a roll coater, a reverse coater, a bar coater, or a slit coater, or a non-contact type application device such as a spinner (rotary application device) or a curtain flow coater to form a coating film.

[0096] After the coating film is formed, the solvent may be removed by a heat treatment (pre-bake (post-apply bake (PAB)) treatment) as appropriate. The pre-baking temperature is appropriately selected taking into consideration the boiling point of the solvent, etc. Pre-baking may be performed at a low temperature under reduced pressure in order to prevent the photosensitive composition from curing before the solvent is sufficiently removed.

[0097] The pre-baking method is not particularly limited, and may be, for example, any of the following: (i) drying using a hot plate at a temperature of 80° C. to 120° C. (preferably 85° C. to 100° C., more preferably 85° C. to 95° C.) for 60 to 120 seconds; (ii) leaving the substrate at room temperature for several hours to several days; or (iii) placing the substrate in a hot air heater or infrared heater for several tens of minutes to several hours to remove the solvent.

[0098] By exposing the coating film formed as described above, an acid is generated from the photocationic curing agent (A), and the generated acid causes the cationic polymerization groups of the acrylic resin (B) to react with each other or with the acrylic resin (B) and the crosslinking agent (C) to form a cured product of the photosensitive composition.

[0099] The exposure is carried out by irradiating the active energy rays such as excimer laser light. The amount of the energy radiation to be irradiated varies depending on the composition of the photosensitive composition, but is, for example, 30 mJ / cm. 2 More than 2000mJ / cm 2 Less than 50 mJ / cm is preferable. 2 More than 500mJ / cm 2 The following is more preferred:

[0100] After the exposure, a heat treatment (post-baking) may be carried out as necessary. By heating after the exposure, the curing of the photosensitive composition can be promoted. The heating temperature after exposure is not particularly limited, but is, for example, 80° C. or more and 120° C. or less, preferably 85° C. or more and 100° C. or less, and more preferably 85° C. or more and 95° C. or less.

[0101] The above method produces a cured product having high light transmittance, and therefore the cured product formed by the above method is suitable for various applications. The thickness of the cured product formed is preferably 100 nm or more and 15 μm or less, and more preferably 400 nm or more and 10 μm or less.

[0102] <Microlens manufacturing method> A method for producing a microlens using the above-mentioned photosensitive composition for forming an optical member will now be described. The method for manufacturing the microlens is as follows: a mask forming step of providing a mask having substantially the same shape as the shape of a lens to be formed on the cured product obtained by the above-mentioned method for producing a cured product; After the mask forming step, the method includes a lens forming step of dry-etching the mask and the cured product to form microlenses to which the shape of the mask is transferred.

[0103] In the mask formation step, an example of a method for providing a mask on a cured product is to form a resist pattern on the cured product, and then reflow the resist pattern by heating to form a mask having substantially the same shape as the shape of the lens to be formed.

[0104] The heating conditions for reflow vary depending on the types and blending ratios of each component in the composition (resist material) used to form the resist pattern, the film thickness of the resist pattern, etc., but the heating temperature is, for example, from 60°C to 150°C (preferably from 70°C to 140°C), and the heating time is, for example, from 0.5 minutes to 60 minutes (preferably from 1 minute to 50 minutes).

[0105] The film thickness of the resist pattern is preferably in the range of 100 nm or more and 4.0 μm or less, and more preferably in the range of 400 nm or more and 2.0 μm or less.

[0106] The dry etching in the lens formation step is not particularly limited, and examples thereof include dry etching using plasma (oxygen, argon, CF4, etc.), corona discharge, and the like.

[0107] Before the mask formation step, a step of forming a patterned cured product by selectively exposing and developing the cured product obtained by the above-mentioned method for producing a cured product may be included. For example, after forming a cured product on the entire surface of a substrate by the above-mentioned method for producing a cured product, the step may remove regions for providing members other than microlenses, such as regions for wiring electrodes and regions for providing partition walls, by development, and the mask formation step may be performed on the cured product that has not been removed.

[0108] By using the above-mentioned photosensitive composition through the above-mentioned steps, a microlens having high light transmittance can be formed. Therefore, the microlens formed by the above-mentioned method is suitable for various applications.

[0109] <Method for manufacturing microlens pattern> A method for producing a microlens pattern using the above-mentioned photosensitive composition for forming an optical member will now be described. The method for manufacturing the microlens pattern includes the steps of: a coating film forming step of coating the photosensitive composition for forming an optical member on a substrate to form a coating film; an exposure step of position-selectively exposing the coating film obtained by the coating film forming step; and a developing step of developing the coating film exposed in the exposure step to obtain a patterned cured product.

[0110] First, in the coating film forming step, a photosensitive composition is applied onto a substrate to form a coating film. The coating film forming step is the same as the coating film forming step in the above <<Method for producing a cured product>>.

[0111] Next, in the exposure step, the coating film obtained in the coating film forming step is exposed to light in a position-selective manner. The exposure step is the same as the exposure step in the above-mentioned <<Method for producing a cured product>>, except that the exposure is performed in a position-selective manner. The position-selective exposure can be performed using a mask having a predetermined shape.

[0112] Next, in the development step, the coating film exposed in the exposure step is developed to obtain a patterned cured product.

[0113] As the developer, for example, an organic alkaline aqueous solution such as an aqueous solution of tetramethylammonium hydroxide (TMAH) or an inorganic alkaline aqueous solution such as sodium hydroxide, potassium hydroxide, sodium metasilicate, or sodium phosphate can be used.

[0114] The patterned cured product may be further heated, preferably at a temperature of 130° C. or lower, more preferably at a temperature of 100° C. or lower.

[0115] By using the photosensitive composition through the above steps, a microlens pattern having high light transmittance can be formed. Therefore, the microlens pattern formed by the above method is suitable for various applications.

[0116] <Microlens> As described above, the photosensitive composition for forming an optical member is exposed to light to form a cured product, which is a microlens. Such a cured product has high light transmittance. Therefore, the microlens is suitable for use in a variety of applications. EXAMPLES

[0117] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0118] [Examples 1 to 3 and Comparative Examples 1 to 2] In the examples and comparative examples, the compound A1 or A2 represented by the following formula was used as the photocationic curing agent (A): Compound A1 was synthesized according to the method described in Example 5 of WO 2017 / 212963. [ka] [ka]

[0119] In the examples and comparative examples, the following resins B1 to B3 were used as the acrylic resin (B). The numbers in the brackets in each structural unit in the following structural formulas indicate the content (mol%) of the structural unit in the resin. The mass average molecular weight Mw of resin B1 is 6,000, the mass average molecular weight Mw of resin B2 is 10,000, and the mass average molecular weight Mw of resin B3 is 10,000. [ka]

[0120] In the examples and comparative examples, a methylated hexamethylolmelamine having the following chemical structure (Nikarak MW-100LM, manufactured by Sanwa Chemical Co., Ltd.) was used as the crosslinking agent (C). [ka]

[0121] The photocationic curing agent (A), the acrylic resin (B), and the crosslinking agent (C), each of the types and amounts shown in Table 1, were dissolved in propylene glycol monomethyl ether to a solid content concentration of 20 mass %, to obtain photosensitive compositions for forming optical members of each of the Examples and Comparative Examples.

[0122] <Optical properties> Cured products were prepared and evaluated according to the following method.

[0123] (Preparation of cured product) The photosensitive compositions for forming optical members of the Examples and Comparative Examples were applied onto a glass substrate in a thickness sufficient to form a cured film having a thickness of 1 μm to form a coating film. The formed coating film was prebaked at 90° C. for 90 seconds and exposed to light at a dose of 100 mJ / m 2 and post-baking at 100° C. for 5 minutes in this order to obtain a cured film.

[0124] (Optical properties of the cured product (transmittance)) The transmittance of light having a wavelength of 400 nm was measured for the cured product prepared using the obtained photosensitive resin composition. The results are shown in Table 1.

[0125] [Table 1]

[0126] According to Examples 1 to 3, a photosensitive composition containing a photocationic curing agent (A), an acrylic resin (B), and a crosslinking agent (C) that does not correspond to the acrylic resin (B), in which the photocationic curing agent (A) is an onium salt containing an anion part of the above-mentioned specific structure, and the acrylic resin (B) is an acrylic resin having a structural unit (b1) having a cationic polymerization group, formed a cured product with high light transmittance. Among them, Example 1, in which the acrylic resin (B) was the acrylic resin B1, formed a cured product with particularly high light transmittance.

[0127] On the other hand, according to Comparative Examples 1 and 2, when the photocationic curing agent (A) contained in the photosensitive resin composition is not an onium salt containing an anion moiety of the specific structure, the light transmittance of the cured product formed is lower than that of Examples 1 to 3.

Claims

1. A photosensitive composition for forming an optical member, comprising: a photocationic curing agent (A); an acrylic resin (B); and a crosslinking agent (C) not corresponding to the acrylic resin (B), The photocationic curing agent (A) is a tetrakis(4-nonafluorobiphenyl)gallate anion, a tetrakis(1-heptafluoronaphthyl)gallate anion, a tetrakis(pentafluorophenyl)gallate anion, a tetrakis(3,4,5-trifluorophenyl)gallate anion, a tetrakis(2-heptafluoronaphthyl)gallate anion, a tetrakis(7-nonafluoroanthryl)gallate anion, a tetrakis(4'-(methoxy)octafluorobiphenyl)gallate anion, a tetrakis(2,4,6-tris(trifluoromethyl)phenyl)gallate anion, a tetrakis(3,5-bis(trifluoromethyl)phenyl)gallate anion, a tetrakis(2,3-bis(pentafluoroethyl)naphthyl)gallate anion, a tetrakis(2-isopropoxy- the onium salt containing one or more anion moieties selected from the group consisting of tetrakis(9,10-bis(heptafluoropropyl)heptafluoroanthryl)gallate anion, tetrakis(9-nonafluorophenanthryl)gallate anion, tetrakis(4-[tri(isopropyl)silyl]-tetrafluorophenyl)gallate anion, tetrakis(9,10-bis(p-tolyl)-heptafluorophenanthryl)gallate anion, tetrakis(4-[dimethyl(t-butyl)silyl]-tetrafluorophenyl)gallate anion, monophenyltris(pentafluorophenyl)gallate anion, and monoperfluorobutyltris(pentafluorophenyl)gallate anion, and a cation moiety represented by the following formula (a2): the acrylic resin (B) has at least a structural unit (b1) represented by the following formula (b1-1) having a cationic polymerization group, and a structural unit (b2) represented by the following formula (b2-1), and the content of the structural unit (b2) is 10 mol % or more and 50 mol % or less based on all structural units of the acrylic resin (B), and is an acrylic resin having a mass average molecular weight of 3,000 or more and 10,000 or less; The content of the acrylic resin (B) is 70 parts by mass or more and 95 parts by mass or less per 100 parts by mass of a solid content of the photosensitive composition for forming an optical member. 【Chemistry 1】 (In formula (a2), R １１ａ ~R １８ａ each independently represents an alkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a hydroxy(poly)alkyleneoxy group, a cyano group, a nitro group, a halogen atom, or a hydrogen atom; R １９ａ ~R ２４ａ each independently represents an alkyl group, a hydroxy group, an alkoxy group, an aryl group, an aryloxy group, a hydroxy(poly)alkyleneoxy group, a cyano group, a nitro group, or a halogen atom; n1 to n4 each independently represent an integer of 0 or more and 1 or less, and when n1 to n4 each represent 0, they represent a direct bond between rings; m1 to m6 are each R １９ａ ~R ２４ａ m1, m4, and m6 each represent an integer of 0 or more and 4 or less, m2 and m5 each represent an integer of 0 or more and 3 or less, and m3 represents an integer of 0 or more and 5 or less. 【Chemistry 2】 (In formula (b1-1), R １ｂ represents a hydrogen atom or a methyl group, R ２ｂ represents a single bond or an alkylene group having 1 to 5 carbon atoms; R ３ｂ represents an epoxy group-containing group, an oxetanyl group-containing group, or an oxolanyl group-containing group. In formula (b2-1), R ４ｂ represents a hydrogen atom or a methyl group, R ５ｂ represents an alkyl group having 1 to 5 carbon atoms, a represents an integer of 1 to 5, b represents an integer of 0 to 4, and a+b is 5 or less; R ５ｂ When there are two or more R ５ｂ may be different from each other or may be the same.)

2. The photosensitive composition for forming an optical member according to claim 1 , wherein n2 and n4 in the formula (a2) are 0.

3. The photosensitive composition for forming an optical member according to claim 1 or 2, wherein the crosslinking agent (C) is a melamine-based compound.

4. A coating film forming step of coating the photosensitive composition for forming an optical member according to any one of claims 1 to 3 on a substrate to form a coating film; an exposure step of exposing the coating film obtained by the coating film forming step; A method for producing a cured product having the formula:

5. a mask forming step of providing a mask having substantially the same shape as a shape of a lens to be formed on the cured product obtained by the method for producing a cured product according to claim 4; a lens forming step of forming a microlens having a shape transferred from the mask by dry etching the mask and the cured product after the mask forming step; The method for manufacturing a microlens includes the steps of:

6. A coating film forming step of coating the photosensitive composition for forming an optical member according to any one of claims 1 to 3 on a substrate to form a coating film; an exposure step of position-selectively exposing the coating film obtained by the coating film forming step; a developing step of developing the coating film exposed in the exposure step to obtain a patterned cured product; A method for manufacturing a microlens pattern having the following structure:

7. A microlens comprising a cured product of the photosensitive composition for forming an optical member according to any one of claims 1 to 3.

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