Resin composition for lens, cured product for lens and lens

Abstract

A resin composition for lenses comprises a photocationic polymerization initiator (X) and an epoxy compound (Y), wherein the photocationic polymerization initiator (X) comprises a salt formed by an anion and a cation represented by general formula (1), and the epoxy compound (Y) contains two or more epoxy groups within its molecule. (In general formula (1), R...) 1~R 4. (Each group independently represents an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 14 carbon atoms)

Description

Technical Field

[0001] This invention relates to a resin composition for a lens, a hardened material for a lens, and a lens. Prior Technology

[0002] Currently, most electronic devices such as smartphones, tablets, and laptops are equipped with cameras. Moreover, with the miniaturization and increasing performance of these devices, there is a strong demand for miniaturization and increasing performance of the lenses used in these cameras.

[0003] Silicone resin or acrylic resin is known to be used as a material in the lens of a camera mounted on these electronic devices (Patent Document 1 and Patent Document 2). Epoxy resin is also known to be used as a material (Patent Document 3). [Existing Technical Documents] [Patent Literature]

[0004] Patent Document 1: Japanese Patent Publication No. 2008-545553 Patent Document 2: Japanese Patent Application Publication No. 2003-131004 Patent Document 3: Japanese Patent Application Publication No. 2019-189874 Summary of the Invention

[0005] [The problem that the invention aims to solve]

[0006] There is room for improvement in the existing lens materials in terms of balancing optical properties, heat resistance, and other properties required by lenses.

[0007] The purpose of this invention is to provide a resin composition for lenses that can form a hardened lens material with low curing shrinkage, high refractive index, high light transmittance and high heat resistance. In addition, the present invention aims to provide a hardened material and lens for a lens that combines low hardening shrinkage, high refractive index, high light transmittance and high heat resistance. [Methods for solving problems]

[0008] The inventors conducted in-depth research to solve the aforementioned problem. As a result, they discovered that the problem could be solved by using a specific photocationic polymerization initiator and an epoxy compound, thus completing this invention.

[0009] That is, according to the present invention, a resin composition for a lens, a hardened material for a lens, and a lens are provided as shown below.

[0010] [1] A resin composition for a lens, comprising: Photocationic polymerization initiator (X) comprises a salt formed by an anion and a cation represented by general formula (1); and Epoxide (Y) contains two or more epoxy groups within its molecule. [Chemistry 1] (In general formula (1), R1 to R4 independently represent alkyl groups with 1 to 18 carbon atoms or aryl groups with 6 to 14 carbon atoms.) [2] As described in [1], the resin composition for lenses, wherein, The epoxy compound (Y) is represented by the general formula (2). [Chemistry 2] (in general formula (2), R5, R6, R8, and R9 independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group. R 7 represents a hydrogen atom or a glycidyl group. n is the average number of repetitions, and represents a real number in the range of 0 to 30. [3] As described in [1] or [2], the resin composition for lenses, wherein, The epoxy compound (Y) has an epoxy equivalent of 100 g / eq or more and 200 g / eq or less. [4] The lens resin composition as described in any one of [1] to [3], wherein, The content of the epoxy compound (Y) in the non-volatile components of the resin composition for the lens is 40% by mass or more. [5] The lens resin composition as described in any one of [1] to [4], wherein, The photocationic polymerization initiator (X) includes an anion represented by either formula (3) or formula (4) as the anion. [Chemistry 3] [Chemistry 4] [6] The lens resin composition as described in any one of [1] to [5], wherein, The photocationic polymerization initiator (X) contains strontium ions as cations. [7] The lens resin composition as described in any one of [1] to [6], wherein, The resin composition for the lens further comprises a monofunctional epoxy compound (Z) represented by general formula (5). [Chemistry 5] (In general formula (5), A is selected from single bond, oxygen atom, sulfur atom, R10 is an alkyl group with 1 to 8 carbon atoms, and any methylene group can be substituted with an oxygen atom) [8] As described in [7], the resin composition for lenses, wherein, The monofunctional epoxy compound (Z) is o-phenylphenol glycidyl ether. [9] The lens resin composition as described in any one of [1] to [8], wherein, The resin composition for the lens further includes an oxobutane compound (W).

[10] The lens resin composition as described in any one of [1] to [9], wherein, The oxetane compound (W) is a biphenyl-type oxetane compound.

[11] The lens resin composition as described in any one of [1] to

[10] , wherein, The viscosity of the resin composition for the lens, measured using an E-type viscometer at a temperature of 25°C and a rotation speed of 2.5 rpm, is ≥100 mPa·s and ≤5000 mPa·s.

[12] The lens resin composition as described in any one of [1] to

[11] , wherein, The resin composition for the lens is coated on a glass plate with a thickness of 250 μm, and UV exposed under conditions of wavelength of 365 nm, irradiation intensity of 150 mW / cm, and cumulative irradiation of 3000 mJ / cm2. The hardened material obtained by heating at 120°C for 30 minutes under nitrogen atmosphere satisfies the necessary conditions (A) to (D) below. (A) The hardening shrinkage rate of the hardened material is more than 1.0% and less than 5.0%. (B) The refractive index of the hardened material is 1.57 or higher. (C) The light transmittance in the thickness direction of the hardened material is 80% or more. (D) The rate of change of light transmittance in the thickness direction of the hardened material after heating (125°C, 168 hours) is less than 10%.

[13] The lens resin composition as described in any one of [1] to

[12] , wherein, The resin composition for lenses is used in wafer-level lenses.

[14] A lens hardener is obtained by hardening the lens resin composition described in any one of [1] to

[13] .

[15] A lens comprising a lens hardener as described in

[14] . [The effects of the invention]

[0011] The resin composition for lenses of the present invention, by including the aforementioned structure, can form a cured material that combines low curing shrinkage, high refractive index, high light transmittance, and high heat resistance. Furthermore, the lens curing material of the present invention is obtained by curing the lens resin composition, thus possessing low curing shrinkage, high refractive index, high light transmittance, and high heat resistance. Furthermore, the lens of the present invention, having a structure obtained by laminating the lens with a hardener, possesses low hardening shrinkage, high refractive index, high light transmittance, and high heat resistance. Simple Explanation of the Diagram

[0012] Figure 1 is a plan view showing an example of the structure of a wafer-level lens array having multiple wafer-level lenses. Implementation

[0013] The present invention will now be described based on embodiments. In this embodiment, unless otherwise specified, "A~B" representing a numerical range means above A and below B. In this embodiment, unless otherwise specified, "having substituents" in alkyl groups refers to the substitution of hydrogen atoms present in its structure by substituents. The position and number of substituents are not particularly limited. Furthermore, when a substituent has carbon atoms, the number of carbon atoms in the group having the substituent does not include the number of carbon atoms in the substituent. For example, in the case of an ethyl group having a phenyl substituent, it is considered an alkyl group with two carbon atoms. In this embodiment, the non-volatile component refers to the component of the lens resin composition after removing volatile components such as solvents.

[0014] [Resin composition for lenses]

[0015] The resin composition for the lens in this embodiment includes a photocationic polymerization initiator (X) and an epoxy compound (Y). The photocationic polymerization initiator (X) includes a salt formed by an anion and a cation represented by general formula (1), and the epoxy compound (Y) contains two or more epoxy groups in its molecule.

[0016] [Chemistry 6]

[0017] In general formula (1), R1 to R4 independently represent alkyl groups having 1 to 18 carbon atoms or aryl groups having 6 to 14 carbon atoms.

[0018] The lens resin composition of this embodiment can be used to form a cured material that combines low curing shrinkage, high refractive index, high light transmittance, and high heat resistance. Although the detailed mechanism is not yet clear, it is speculated that since the photocationic polymerization initiator containing anionic gallium hardly produces strong acid components even when heated, it suppresses heat-induced degradation such as coloration. In addition, the photocationic polymerization initiator containing anionic gallium can achieve polymerization performance at the level of the prior art, while suppressing adverse effects on various properties such as curing shrinkage, refractive index, and light transmittance.

[0019] The components contained in the resin composition for the lens of this embodiment will be described in detail below.

[0020] <Photocationic Polymerization Initiator (X)>

[0021] The resin composition for the lens in this embodiment includes a photocationic polymerization initiator (X), which comprises a salt formed by an anion and a cation represented by general formula (1).

[0022] [Chemistry 7]

[0023] In general formula (1), R1 to R4 independently represent alkyl groups having 1 to 18 carbon atoms or aryl groups having 6 to 14 carbon atoms.

[0024] The alkyl groups represented by R1 to R4 of general formula (1) having 1 to 18 carbon atoms are not limited to any of the straight-chain, branched-chain or cyclic forms. Specific examples include: alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, tributyl, hexyl, octyl, 2-ethylhexyl or decyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, cyclooctyl, norbornyl, bicyclononyl or tricyclodecyl; etc.

[0025] Specific examples of aryl groups with 6 to 14 carbon atoms represented by R1 to R4 in general formula (1) include: phenyl, tolyl, naphthyl, biphenyl, terphenyl, phenanthryl or anthracene, etc.

[0026] The alkyl groups with 1 to 18 carbons or the aryl groups with 6 to 14 carbons represented by R1 to R4 in general formula (1) may have substituents.

[0027] The substituents that the alkyl group with 1 to 18 carbons or the aryl group with 6 to 14 carbons represented by R1 to R4 in general formula (1) may have are not particularly limited. Examples include: halogen atoms, hydrocarbon groups, halogen-containing groups, oxygen-containing groups, sulfur-containing groups and nitrogen-containing groups.

[0028] Examples of halogen atoms include fluorine, chlorine, and bromine atoms.

[0029] Examples of hydrocarbon groups include: alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, tributyl, hexyl, octyl, 2-ethylhexyl, or decyl; cycloalkyl groups such as cyclopentyl, cyclohexyl, cyclooctyl, norbornyl, bicyclononyl, or tricyclodecyl; aryl groups such as phenyl, tolyl, naphthyl, biphenyl, terphenyl, phenanthrene, or anthracene; aralkyl groups such as benzyl or phenylethyl; diene divalent derivatives such as 1,3-butadienyl, isoprene (2-methyl-1,3-butadienyl), isoprene (1,3-pentadienyl), 2,4-hexadienyl, 1,4-diphenyl-1,3-pentadienyl, or cyclopentadienyl; etc.

[0030] Examples of halogenated groups that can be present in alkyl groups having 1 to 18 carbon atoms, represented by R1 to R4, include: trifluoromethyl, pentafluoroethyl, 1,1,1,3,3,3-hexafluoro-2-propyl or nonafluoro-tert-butyl, etc.; halogenated aryl groups such as pentafluorophenyl and pentachlorophenyl; etc.

[0031] Examples of oxygen-containing groups include: alkoxy groups such as methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, or tributoxy; aryloxy groups such as phenoxy, 2,6-dimethylphenoxy, or 2,4,6-trimethylphenoxy; ester groups such as acetoxy, benzoxy, methoxycarbonyl, phenoxycarbonyl, or p-chlorophenoxycarbonyl; ether groups; acetyl, acetyl, benzyl, p-chlorobenzoyl, or p-methoxybenzoyl; carboxyl groups; carbonate groups; hydroxyl groups; peroxide groups; carboxylic anhydride groups; furanyl groups; etc.

[0032] Examples of sulfur-containing groups include: mercapto; thioester groups such as acetylthio, benzothio, methylthiocarbonyl, or phenylthiocarbonyl; dithioester group; alkylthio group such as methylthio or ethylthio; arylthio group such as phenylthio, methylphenylthio, or naphthio; thioacryl; thioether group; thiocyanate group; isothiocyanate group; sulfonate group such as methyl sulfonate, ethyl sulfonate, or phenyl sulfonate; sulfonamide group such as phenylsulfonamide, N-methylsulfonamide, or N-methyl-p-toluenesulfonamide; thiocarboxyl; dithiocarboxyl; sulfonyl; sulfonyl; sulfinyl; sulfinyl; etc.

[0033] Examples of nitrogen-containing groups include: amino; alkylamino groups such as dimethylamino or ethylmethylamino; arylamino groups such as diphenylamino; imino; alkylimino groups such as methylimino, ethylimino, propylimino or butylimino; arylimino groups such as phenylimino; acetamino; alkylacetamino or N-methylacetamino; arylacetamino; acetamino; alkylacetamino; arylacetamino; pyrrolidinyl; hydrazyl; hydrazinyl; nitro; nitrosyl; cyano; isocyano; cyanate ester; amidine; diazo; etc.

[0034] Preferably, three or more of R1 to R4 are aryl groups having 6 to 14 carbon atoms, and more preferably, all of R1 to R4 are aryl groups having 6 to 14 carbon atoms.

[0035] R1 to R4 are preferably substituents containing halogen atoms, and more preferably substituents containing fluorine atoms. Specifically, the photocationic polymerization initiator (X) is preferably an anion containing either formula (3) or formula (4). This further improves the heat resistance of the hardened lens body formed from the lens resin composition.

[0036] [Chemistry 8]

[0037] [Chemistry 9]

[0038] The photocationic polymerization initiator (X) contains a cation that forms a salt with the anion represented by the general formula (1).

[0039] There are no particular limitations on the cation that forms a salt with the anion represented by general formula (1), as long as it is a monovalent cation. Examples include: oxonium ion, ammonium ion, phosphonium ion, strontium ion, or iodonium ion.

[0040] Examples of oxonium ions include: trimethyloxonium, diethylmethyloxonium, triethyloxonium, and tetramethylenemethyloxonium; pyraniums such as 4-methylpyranium, 2,4,6-trimethylpyranium, 2,6-di-tert-butylpyranium, and 2,6-diphenylpyranium; chromeneiums such as 2,4-dimethylchromeneium and 1,3-dimethylisochromeneium; and isochromeneium; etc.

[0041] Examples of ammonium ions include: pyrrolidine-onium such as N,N-dimethylpyrrolidine-onium, N-ethyl-N-methylpyrrolidine-onium, and N,N-diethylpyrrolidine-onium; imidazoline-onium such as N,N'-dimethylimidazoline-onium, N,N'-diethylimidazoline-onium, N-ethyl-N'-methylimidazoline-onium, 1,3,4-trimethylimidazoline-onium, and 1,2,3,4-tetramethylimidazoline-onium; tetrahydropyrimidine-onium such as N,N'-dimethyltetrahydropyrimidine-onium; and N,N'-dimethyl... Morpholinium, etc.; piperidinium, etc.; pyridinium, such as N,N'-diethylpiperidineonium; N-methylpyridinium, N-benzylpyridinium and N-benzomethylpyridinium; imidazolineium, such as N,N'-dimethylimidazolineonium; quinolineium, such as N-methylquinolineonium, N-benzylquinolineon and N-benzomethylquinolineonium; isoquinolineium, such as N-methylisoquinolineonium; thiazolineium, such as benzylbenzothiazolineonium and benzomethylbenzothiazolineonium; acridineonium, such as benzyl acridineonium and benzomethyl acridineonium, etc.

[0042] Examples of phosphonium ions include: tetraphenylphosphonium, tetra-p-tolylphosphonium, tetra(2-methoxyphenyl)phosphonium, tetra(3-methoxyphenyl)phosphonium and tetra(4-methoxyphenyl)phosphonium, etc.; triphenylbenzylphosphonium, triphenylbenzylmethylphosphonium, triphenylmethylphosphonium and triphenylbutylphosphonium, etc.; tetraalkylphosphonium, triethylbenzylphosphonium, tributylbenzylphosphonium, tetraethylphosphonium, tetrabutylphosphonium, tetrahexylphosphonium, triethylbenzylmethylphosphonium and tributylbenzylmethylphosphonium, etc.; etc.

[0043] Examples of strontium ions include: triphenylstrontium, tri-p-tolylstrontium, tri-o-tolylstrontium, tri(4-methoxyphenyl)strontium, 1-naphthyldiphenylstrontium, 2-naphthyldiphenylstrontium, tri(4-fluorophenyl)strontium, tri-1-naphthylstrontium, tri-2-naphthylstrontium, tri(4-hydroxyphenyl)strontium, 4-(phenylthio)phenyldiphenylstrontium, 4-(p-tolylthio)phenyldi-p-tolylstrontium, 4-(4-methoxyphenylthio)phenylbis(4-methoxyphenyl)strontium, 4-(phenylthio)phenylbis(4-fluorophenyl)strontium, 4-(phenylthio)phenylbis(4-methoxyphenyl)strontium, and 4-(phenylthio)phenyldi-p-tolylstrontium. 4-(4-biphenylthio)phenyl]-4-biphenylphenyl strontium, [4-(2-thioxanthone-thio)phenyl]diphenyl strontium, bis[4-(diphenyl strontium(sulfonio))phenyl] sulfide, bis[4-{bis[4-(2-hydroxyethoxy)phenyl]strontium}phenyl] sulfide, bis{4-[bis(4-fluorophenyl)strontium]phenyl} sulfide, bis{4-[bis(4-methylphenyl)strontium]phenyl} sulfide, bis{4-[bis(4-methoxyphenyl)strontium]phenyl} sulfide, 4-(4-benzoyl-2-chlorophenylthio)phenyl bis(4-fluorophenyl)strontium, 4-(4-benzoyl-2-chlorophenylthio)phenyl bis(4-fluorophenyl)strontium, 4-(4-benzoyl-2-chlorophenylthio)phenyl bis(4-fluorophenyl)strontium, -2-chlorophenylthio)phenyldiphenyl strontium, 4-(4-benzopyroxyphenylthio)phenylbis(4-fluorophenyl)strontium, 4-(4-benzopyroxyphenylthio)phenyldiphenyl strontium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracene-2-yldi-p-tolyl strontium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracene-2-yldiphenyl strontium, 2-[(di-p-tolyl)strontium]thioxanthone, 2-[(diphenyl)strontium]thioxanthone, 4-(9-oxo-9H-thioxanth-2-yl)thiophenyl-9-oxo-9H-thioxanth-2-ylphenyl strontium, 4-[4-(4- Triaryl strontium such as 4-[4-(4-tert-butylbenzoyl)phenylthio]phenyldiphenylstrontium, 4-[4-(benzoylphenylthio)]phenyldiphenylstrontium, 4-[4-(benzoylphenylthio)]phenyldiphenylstrontium, 5-(4-methoxyphenyl)thianthane, 5-phenylthianthianthane, 5-tolylthianthianthane, 5-(4-ethoxyphenyl)thianthianthane, and 5-(2,4,6-trimethylphenyl)thianthianthane; diaryl strontium such as diphenylbenzomethylstrontium, diphenyl-4-nitrobenzomethylstrontium, diphenylbenzylstrontium, and diphenylmethylstrontium;Phenylacetylbenzyl strontium, 4-hydroxyphenylmethylbenzyl strontium, 4-methoxyphenylmethylbenzyl strontium, 4-ethoxycarbonyloxyphenylmethylbenzyl strontium, 4-hydroxyphenyl(2-naphthylmethyl)methyl strontium, 2-naphthylmethylbenzyl strontium, 2-naphthylmethyl(1-ethoxycarbonyl)ethyl strontium, phenylmethylbenzylmethyl strontium, 4-hydroxyphenylmethylbenzylmethyl strontium, 4-methoxyphenyl Monoaryl strontium spars include methylbenzylmethylstrontium, 4-acetylatedoxophenylmethylbenzylmethylstrontium, 2-naphthylmethylbenzylmethylstrontium, 2-naphthyloctadecylbenzylmethylstrontium, and 9-anthraylmethylbenzylmethylstrontium; trialkylstrontium spars include dimethylbenzylmethylstrontium, benzoylmethyltetrahydrothiophenonium, dimethylbenzylstrontium, benzyltetrahydrothiophenonium, and octadecylmethylbenzylmethylstrontium.

[0044] Examples of iodonium ions include: diphenyliodonium, di-p-tolyliodonium, bis(4-dodecylphenyl)iodonium, bis(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium, bis(4-decyloxy)phenyliodonium, 4-(2-hydroxytetradecyloxy)phenylphenyliodonium, 4-isopropylphenyl(p-tolyl)iodonium, and 4-isobutylphenyl(p-tolyl)iodonium.

[0045] The photocationic polymerization initiator (X) preferably contains ammonium ions, phosphonium ions, strontium ions or iodonium ions as cations, more preferably contains strontium ions or iodonium ions, and even more preferably contains strontium ions.

[0046] The photocationic polymerization initiator (X) is preferably a salt containing an anion represented by either formula (3) or formula (4) and strontium ions. This further improves the heat resistance of the hardened lens body formed from the lens resin composition.

[0047] [Chemistry 10]

[0048] [Chemistry 11]

[0049] The following examples illustrate specific examples of anions contained in the photocationic polymerization initiator (X), but the anions contained in the photocationic polymerization initiator (X) in this embodiment are not limited to these anions.

[0050] [Chemistry 12]

[0051] Photocationic polymerization initiator (X) can be synthesized, for example, by a known method as described in International Publication No. 2018 / 020974, etc. Alternatively, commercially available CPI-310FG (trade name, photocationic polymerization initiator, manufactured by SAN-APRO) can also be used.

[0052] The content of photocationic polymerization initiator (X) relative to 100 parts by weight of epoxy compound (Y) is preferably 0.05 parts by weight to 15 parts by weight, more preferably 0.07 parts by weight to 10 parts by weight, further preferably 0.1 parts by weight to 8 parts by weight, and most preferably 0.5 parts by weight to 5 parts by weight. The photocationic polymerization initiator (X) can be used alone or in combination. When multiple photocationic polymerization initiators (X) are used in combination, the total content of each photocationic polymerization initiator (X) is taken as the content of the photocationic polymerization initiator (X).

[0053] Furthermore, when the molar absorptivity of the photocationic polymerization initiator (X) is high at wavelengths of 300 nm to 380 nm, the content can be adjusted to an appropriate level depending on the volume or thickness of the resin composition used for lenses.

[0054] <Epoxy compound (Y)> The resin composition for the lens in this embodiment contains an epoxy compound (Y) having two or more epoxy groups within its molecule.

[0055] Examples of epoxy compounds (Y) containing two or more epoxy groups in the molecule include: diethylene glycol diglycidyl ether, hexanediol diglycidyl ether, dimethylolpropane diglycidyl ether, polypropylene glycol diglycidyl ether, trimethylolpropane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0056] In addition, examples of alicyclic epoxy resins (Y) containing two or more epoxy groups in the molecule include 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate and ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate.

[0057] Furthermore, examples of epoxy compounds (Y) containing two or more epoxy groups in the molecule include: bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, biphenyl-phenol phenolic varnish type epoxy compounds, and epoxy compounds in which some or all of the alcoholic hydroxyl groups in their structure are epoxidized, as well as epoxy resins with aromatic rings.

[0058] Commercially available epoxy compounds (Y) include: EPICLON series (bisphenol A type epoxy resin, manufactured by DIC Corporation), represented by EXA-850CRP; jER series (manufactured by Mitsubishi Chemical Corporation), represented by jER828; YD series (manufactured by Nippon Steel Chemical & Materials Co., Ltd.), represented by YD-127; and TECHMORE VG3101L (trifunctional epoxy resin, manufactured by Printec Corporation), etc.

[0059] The epoxy compound (Y) is preferably an epoxy compound having an aromatic ring. This increases the refractive index of the hardened material formed by curing the resin composition of the lens, thereby improving the optical properties of the lens.

[0060] The epoxy compound (Y) is preferably the compound represented by general formula (2).

[0061] [Chemistry 13]

[0062] In general formula (2), R5, R6, R8, and R9 independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a trifluoromethyl group. R 7 represents a hydrogen atom or a glycidyl group. n is the average number of repetitions, and represents a real number in the range of 0 to 30.

[0063] As alkyl groups having 1 to 4 carbons represented by R5, R6, R8 and R9, examples can be given of groups having 1 to 4 carbons that are alkyl groups having 1 to 18 carbons represented by R1 to R4.

[0064] R5, R6, R8 and R9 are preferably alkyl or trifluoromethyl with 1 to 4 carbon atoms, more preferably methyl or trifluoromethyl, and even more preferably methyl.

[0065] n is preferably 1~20, more preferably 5~15. Furthermore, n is calculated based on the weight average molecular weight, which is calculated by converting polystyrene based on the results of gel permeation chromatography (GPC).

[0066] There are no particular limitations on the epoxy equivalent of the epoxy compound (Y), but it is preferably 100 g / eq or more and 200 g / eq or less, and more preferably 120 g / eq or more and 180 g / eq or less. Furthermore, the epoxy equivalent in this specification is a value obtained by measuring according to the method of Japanese Industrial Standard (JIS) K7236.

[0067] In this embodiment, the content of epoxy compound (Y) in the non-volatile component of the lens resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 70% by mass or more. The upper limit of the content of epoxy compound (Y) in the non-volatile component of the resin composition for the lens in this embodiment is not particularly limited, and is usually 99% by mass or less. Epoxy compound (Y) may be used alone or in combination. When multiple epoxy compounds (Y) are used in combination, the total content of each epoxy compound (Y) shall be taken as the content of epoxy compound (Y).

[0068] <Other Ingredients> The resin composition for the lens in this embodiment may, as needed, contain monofunctional epoxy compounds (Z), oxetane compounds (W), solvents, adhesion promoters, polyol compounds, polyphenol compounds, sensitizers, ion traps, photocationic polymerization initiators other than photocationic polymerization initiators (X), etc.

[0069] (Monofunctional epoxy compound (Z)) The resin composition for the lens in this embodiment is preferably a monofunctional epoxy compound (Z) represented by general formula (5). This further improves the heat resistance of the hardened lens body formed from the lens resin composition. Additionally, it improves the glass adhesion of the lens resin composition.

[0070] [Chemistry 14]

[0071] In general formula (5), A is selected from single bond, oxygen atom, sulfur atom, R10 is an alkyl group with 1 to 8 carbon atoms, and any methylene group can be substituted with an oxygen atom.

[0072] R 10 is preferably an alkyl group having 1 to 4 carbon atoms, and more preferably an alkyl group having 1 to 2 carbon atoms.

[0073] R 10 is preferably any methylene group substituted with an oxygen atom.

[0074] The preferred monofunctional epoxy compound (Z) is o-phenylphenol glycidyl ether.

[0075] Commercially available monofunctional epoxy compounds (Z) include: OPP-EP (o-phenylphenol glycidyl ether, manufactured by Yokkaichi Synthetic Co., Ltd.) and OPP-G (o-phenylphenol glycidyl ether, manufactured by Sanko Co., Ltd.).

[0076] When the lens resin composition of this embodiment contains a monofunctional epoxy compound (Z), its content in the non-volatile components of the lens resin composition of this embodiment is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. When the lens resin composition of this embodiment contains a monofunctional epoxy compound (Z), its content in the non-volatile components of the lens resin composition of this embodiment is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0077] In the case where the resin composition for the lens in this embodiment contains a monofunctional epoxy compound (Z), the content of the epoxy compound (Y) is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of the epoxy compound (Y). In the case where the resin composition for the lens in this embodiment contains a monofunctional epoxy compound (Z), the content of the epoxy compound (Y) relative to 100 parts by mass is, for example, 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 100 parts by mass or less, further preferably 80 parts by mass or less, further preferably 60 parts by mass or less, further preferably 40 parts by mass or less, and further preferably 25 parts by mass or less.

[0078] Monofunctional epoxy compound (Z) can be used alone or in combination. When multiple monofunctional epoxy compounds (Z) are used in combination, the total content of each monofunctional epoxy compound (Z) is taken as the content of monofunctional epoxy compound (Z).

[0079] (Oxycyclic butane compounds) The resin composition for the lens in this embodiment preferably further comprises an oxetane compound (W). This further improves the heat resistance of the hardened lens body formed from the lens resin composition. Additionally, it improves the glass adhesion of the lens resin composition. Furthermore, it improves the curing properties of the resin composition.

[0080] The oxetane compound (W) is not particularly limited, and commonly known compounds may be used. Specific examples of oxetane resins include: oxetane, 2-methyloxetane, 3-methyloxetane, 2,2-dimethyloxetane, 3,3-dimethyloxetane, 3-ethyl-3-hydroxymethyloxetane, and biphenyl-type oxetanes, etc.

[0081] Oxybutane compound (W) may be used alone or in combination. In the case of using multiple compounds in combination, the total content of each oxybutane compound (W) shall be taken as the content of oxybutane compound (W).

[0082] Oxycyclic butane compounds (W) are preferably biphenyl-type oxycyclic butane compounds. Specific examples of biphenyl-type oxycyclic butanes include, for instance, xylyldioxane.

[0083] Commercially available oxetane compounds (W) include: Aron Oxetane (3-ethyl-3-hydroxymethyloxetane, manufactured by Dong-A Synthetic Co., Ltd.) and Aron Oxetane OXT-121 (extrinyldioxetane, manufactured by Dong-A Synthetic Co., Ltd.).

[0084] When the lens resin composition of this embodiment contains an oxacyclobutane compound (W), from the viewpoint of improving glass adhesion, heat resistance and curability, its content in the non-volatile components of the lens resin composition of this embodiment is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, more preferably 1% by mass or more, and more preferably 2% by mass or more. When the resin composition for the lens in this embodiment contains an oxetane compound (W), its content is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less.

[0085] In the case where the lens resin composition of this embodiment contains oxocyclobutane resin (W), its content is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 10 parts by mass or more, relative to 100 parts by mass of epoxy compound (Y). When the lens resin composition of this embodiment contains oxetane resin (W), its content is, for example, 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 80 parts by mass or less, even more preferably 60 parts by mass or less, even more preferably 40 parts by mass or less, even more preferably 25 parts by mass or less, even more preferably 15 parts by mass or less.

[0086] (solvent) The solvent contained in the lens resin composition of this embodiment is not particularly limited, but preferably a solvent capable of dissolving each component of the lens resin composition is used. Examples of such organic solvents include: ketones such as acetone, ethyl methyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; aromatic hydrocarbons such as toluene, xylene, methoxybenzene, and tetramethylbenzene; glycol ethers such as diethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, and dipropylene glycol diethyl ether; ethyl lactate, butyl lactate, propyl lactate, ethyl acetate, methyl acetoacetate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl 2-hydroxypropionate, ethyl 2-hydroxypropionate, methyl propionate, methyl propionate, ethyl propionate, methyl ... Esters such as 3-methoxypropionate, ethyl-3-methoxypropionate, ethyl-3-ethoxypropionate, propyl-3-methoxypropionate, butyl acetate, butyl cellulose acetate, carbitol acetate, and propylene glycol monomethyl ether acetate; lactones such as α-acetyl lactone, β-propiolactone, γ-butyrolactone, and δ-valerolactone; alcohols such as methanol, ethanol, cellulose, and methyl cellulose; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, naphtha, hydrogenated naphtha, and solvent naphtha; etc.

[0087] When the resin composition for the lens in this embodiment contains a solvent, its content is not particularly limited as long as it is within the range that does not impair the effect of the present invention. It is usually 95% by mass or less, and preferably 10% to 90% by mass. Solvents may be used alone or in combination. When multiple solvents are used in combination, the total content of each solvent is taken as the solvent content.

[0088] When the epoxy compound (Y) is liquid at room temperature, coating can be performed relatively well even without the preparation of a solvent or with virtually no solvent.

[0089] (Adhesion-giving agent) The adhesion promoter contained in the resin composition for the lens in this embodiment is not particularly limited, and known silane coupling agents or titanium coupling agents can be used. From the viewpoint of improving glass adhesion, it is preferable to use a silane coupling agent.

[0090] Examples of silane coupling agents include: 3-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-mercaptopropyltrimethoxysilane, 8-glycidyloctyltrimethoxysilane, etc.

[0091] When the lens resin composition of this embodiment contains an adhesion promoter, its content is not particularly limited as long as it does not impair the effect of the present invention. In the non-volatile component of the lens resin composition of this embodiment, it is preferably 15% by mass or less, more preferably 10% by mass or less, even more preferably 5% by mass or less, and even more preferably 2% by mass or less. When the lens resin composition of this embodiment contains an adhesion promoter, its content is not particularly limited as long as it does not impair the effect of the present invention. In the non-volatile component of the lens resin composition of this embodiment, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 0.8% by mass or more. Adhesion enhancers can be used alone or in combination. When multiple adhesive enhancers are used in combination, the total content of each adhesive enhancer is taken as the content of the adhesive enhancer.

[0092] (Polyol compounds) The polyol compound contained in the resin composition for the lens in this embodiment is not particularly limited, but typically it is a polyester polyol compound containing hydroxyl groups that react with epoxy groups under the influence of a strong acid catalyst. For example, the polyol compound listed in Japanese Patent Publication No. 5901070 can be used.

[0093] In the case where the resin composition for the lens in this embodiment contains a polyol compound, its content is not particularly limited as long as it is within the range that does not impair the effect of the present invention. It is usually 1 to 30 parts by mass relative to 100 parts by mass of epoxy compound (Y), and preferably 2 to 25 parts by mass. A single polyol compound may be used, or multiple compounds may be used in combination. In the case of multiple compounds being used in combination, the total content of each polyol compound shall be taken as the content of the polyol compound.

[0094] The polyphenolic compound contained in the resin composition of the lens in this embodiment is a compound that can be cured by heating to increase the crosslinking density of the epoxy compound. For example, the polyphenolic compound listed in Japanese Patent Publication No. 5967824 can be used.

[0095] (Polyphenolic compounds) In the case where the resin composition for the lens in this embodiment contains a polyphenol compound, its content is not particularly limited as long as it is within the range that does not impair the effect of the present invention. It is usually 3 to 40 parts by mass relative to 100 parts by mass of epoxy compound (Y), preferably 4 to 30 parts by mass, and more preferably 5 to 25 parts by mass. A single polyphenol compound may be used, or multiple compounds may be used in combination. In the case of multiple compounds being used in combination, the total content of each polyphenol compound shall be taken as the content of the polyphenol compound.

[0096] (Sensitizer) The sensitizer contained in the resin composition of the lens in this embodiment serves to provide the absorbed light energy to the photocationic polymerization initiator. Examples include thioxanthones and anthracene compounds (9,10-dialkoxyanthracene derivatives) having alkoxy groups at the 9 and 10 positions.

[0097] When the resin composition for the lens in this embodiment contains a sensitizer, its content is not particularly limited as long as it is within the range that does not impair the effect of the present invention. It is preferably 30 parts by weight or less, and more preferably 20 parts by weight or less, relative to 100 parts by weight of the photocationic polymerization initiator (X). In the case where the resin composition for the lens in this embodiment contains a sensitizer, its content is not particularly limited as long as it is within the range that does not impair the effect of the present invention, and is usually 0.1 parts by mass or more relative to 100 parts by mass of the photocationic polymerization initiator (X). A single sensitizer may be used, or multiple sensitizers may be used in combination. In the case of multiple sensitizers being used in combination, the total content of each sensitizer shall be taken as the content of the sensitizer.

[0098] (ion trapping agent) The ion trapping agent contained in the resin composition of the lens in this embodiment can reduce the adverse effects of ions from the photocationic polymerization initiator (X). For example, organoaluminum compounds or onium salt compounds that generate weak acids by ultraviolet irradiation can be used as ion trapping agents.

[0099] When the resin composition for the lens in this embodiment contains an ion trap, its content is not particularly limited as long as it does not impair the effects of the present invention. In the case of an organoaluminum compound, the content is preferably 0.1 to 10 parts by weight relative to 100 parts by weight of the photocationic polymerization initiator (X). In the case of an onium weak acid salt compound, the content is preferably 0.001 to 2 parts by weight relative to 100 parts by weight of the photocationic polymerization initiator (X). Ion trapping agents can be used alone or in combination. When multiple agents are used in combination, the total content of each ion trapping agent is taken as the content of the ion trapping agent.

[0100] (Other photocationic polymerization initiators) The resin composition for the lens in this embodiment may also contain photocationic polymerization initiators other than photocationic polymerization initiator (X) (other photocationic polymerization initiators). The other photocationic polymerization initiators contained in the resin composition for the lens in this embodiment are not particularly limited, and known photocationic polymerization initiators can be used.

[0101] Other examples of photocationic polymerization initiators include [(R 20) sB(Phf) 4-s]- (where R 20 represents a phenyl or biphenyl; Phf represents a phenyl with at least one hydrogen atom substituted by at least one of perfluoroalkyl, perfluoroalkoxy, and halogen atoms; s is an integer from 0 to 3), BF 4-, [(Rf) nPF 6-n]- (Rf: an alkyl group with more than 80% hydrogen atoms substituted by fluorine atoms, n: an integer from 0 to 5), AsF 6-, SbF 6-, pentafluorohydroxyantimonate, etc., as anionic initiators.

[0102] The content of other photocationic polymerization initiators is not particularly limited as long as it does not impair the effect of the present invention. It is preferably 50 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, relative to 100 parts by mass of photocationic polymerization initiator (X).

[0103] Other photocationic polymerization initiators may be used alone or in combination. In the case of using multiple combinations, the total content of each other photocationic polymerization initiator shall be taken as the content of the other photocationic polymerization initiator.

[0104] (Other additives) In addition to the components described above, the resin composition for the lens in this embodiment may also contain various additives such as antioxidants, light stabilizers, thermoplastic resins, colorants, tackifiers, defoamers, and leveling agents as needed.

[0105] The resin composition for the lens in this embodiment preferably contains an antioxidant.

[0106] Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, thioether antioxidants, and hindered amine antioxidants.

[0107] The antioxidants are preferably phenolic antioxidants, and more preferably hindered phenolic antioxidants.

[0108] Examples of hindered phenolic antioxidants include 2,6-di-tert-butylhydroxytoluene and pentaerythritol tetra[3-(3,5-di-tert-butyl-4-hydroxyphenyl]propionate]. Commercially available hindered phenolic antioxidants include, for example, the Adekastab series AO-20, AO-30, AO-40, AO-50, AO-60 and AO-80 manufactured by ADEKA Corporation.

[0109] Examples of phosphorus-based antioxidants include: phosphines such as trialkylphosphine and triarylphosphine, trialkyl phosphite esters, and triaryl phosphite esters. Commercially available phosphorus-based antioxidants include, for example, the Adekastab series manufactured by ADEKA Corporation, such as PEP-4C, PEP-8, PEP-24G, PEP-36, HP-10, 260, 522A, 329K, 1178, 1500, 135A, and 3010.

[0110] Commercially available thioether-based antioxidants include, for example, the Adekastab series AO-26, AO-412S, and AO-503A manufactured by ADEKA Corporation.

[0111] Examples of hindered amine antioxidants include bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, 2,4-bis[N-butyl-N-(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)amino]-6-(2-hydroxyethylamine)-1,3,5-triazine, bis(2,2,6,6-tetramethyl-1-(octoxy)-4-piperidinyl) decanoate, and bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate. Examples of commercially available hindered amine antioxidants include: AL-72 from the Adekastab series manufactured by ADEKA Inc., and hindered amine antioxidants such as 111FDL, 123, 144, 152, 292 and 5100 from the TINUVIN series manufactured by BASF.

[0112] When using two or more antioxidants together, it is preferable to use phenolic antioxidants and hindered amine antioxidants together, or phenolic antioxidants and thioether antioxidants together.

[0113] When the resin composition for the lens in this embodiment contains an antioxidant, its content can be appropriately set according to the purpose. However, from the viewpoint of obtaining a cured product with less coloring, when the total amount of epoxy compound (Y), monofunctional epoxy compound (Z) and oxetane compound (W) is set to 100 parts by mass, it is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, relative to the total amount of 100 parts by mass. Moreover, from the viewpoint of obtaining a resin composition with excellent curability, it is preferably 5 parts by mass or less, more preferably 1 part by mass or less.

[0114] The resin composition for the lens in this embodiment preferably contains a light stabilizer.

[0115] The light stabilizer in this embodiment is preferably a hindered amine light stabilizer. Examples of hindered amine light stabilizers include compounds and commercially available products such as bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, which are examples of hindered amine antioxidants.

[0116] When the resin composition for the lens in this embodiment contains a light stabilizer, regarding its content, when the total amount of epoxy compound (Y), monofunctional epoxy compound (Z) and oxetane compound (W) is set to 100 parts by mass, it is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, and more preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, relative to the total amount of 100 parts by mass.

[0117] <Manufacturing Method> The resin composition for the lens in this embodiment can be obtained by mixing the components and stirring using conventional methods. Alternatively, dispersion and mixing can be performed using a dissolver, homogenizer, three-roll mill, or other disperser as needed. Furthermore, after mixing, filtration can be performed using a mesh or membrane filter.

[0118] <Physical properties> The viscosity of the resin composition for the lens in this embodiment can be measured, for example, by using an E-type viscometer. When measuring the viscosity of the resin composition for the lens of this embodiment using an E-type viscometer at a temperature of 25°C and a rotation speed of 2.5 rpm, the viscosity is preferably 100 mPa·s or more and 5000 mPa·s or less, more preferably 200 mPa·s or more and 3000 mPa·s or less, and even more preferably 500 mPa·s or more and 2000 mPa·s or less.

[0119] Regarding the lens resin composition of this embodiment, the lens resin composition is coated on a glass plate with a thickness of 250 μm, and subjected to UV exposure at a wavelength of 365 nm, an irradiation intensity of 150 mW / cm, and a cumulative irradiation dose of 3000 mJ / cm². The resulting hardened lens material (α) is heated at 120°C for 30 minutes under a nitrogen atmosphere. The curing shrinkage rate is preferably 1.0% or more and 5.0% or less, more preferably 1.2% or more and 4.0% or less, and even more preferably 1.5% or more and 3.0% or less. By making the curing shrinkage rate of the lens curing material (α) within the range described, the dimensional accuracy during lens manufacturing can be improved.

[0120] The curing shrinkage rate of the hardener (α) for lenses can be determined by the following procedure. First, the specific gravity d1 of the resin composition for lenses is determined according to JIS Z 8804:2012 (method for determination of density and specific gravity of liquids). Then, if the resin composition for lenses contains volatile components, the specific gravity of the non-volatile components after removing the volatile components is determined. Next, the specific gravity d2 of the hardened material (α) for lenses was determined according to JIS Z 8807:2012 (method for determination of density and specific gravity of solids). Using the determined specific gravity value, the hardening shrinkage rate was calculated by the following formula. Hardening shrinkage rate (%) = (1 - d1 / d2) × 100

[0121] The refractive index of the lens resin composition of this embodiment obtained under the stated conditions as a hardened lens material (α) is preferably 1.57 or higher, more preferably 1.58 or higher, and even more preferably 1.59 or higher. By making the refractive index of the lens hardener (α) within the aforementioned range, the optical properties of the lens can be improved.

[0122] The refractive index of the hardened material (α) for the lens can be measured using an Abbe refractometer.

[0123] The light transmittance T1 in the thickness direction of the lens resin composition obtained under the stated conditions is preferably 80% or more. By making the light transmittance of the lens hardener (α) within the range mentioned above, a lens with higher transparency can be manufactured.

[0124] The light transmittance T1 in the thickness direction of the hardened material (α) for the lens can be measured using a UV-Vis-NIR spectrophotometer at a wavelength of 400 nm by the transmittance method.

[0125] The rate of change of light transmittance in the thickness direction of the lens resin composition obtained under the stated conditions (125°C, 168 hours) after heating (10% or less, more preferably 5% or less, and even more preferably 2% or less) is preferably 10% or less, more preferably 5% or less, and even more preferably 2% or less. By making the rate of change of light transmittance of the lens hardener (α) after heating within the range stated, a lens with superior heat resistance can be manufactured.

[0126] The rate of change of light transmittance in the thickness direction of the hardened material (α) for the lens after heating (125°C, 168 hours) can be determined by the following procedure. First, the lens hardener (α) was heated in an oven at 125°C in air for 168 hours. Then, the light transmittance in the thickness direction was measured under the conditions to obtain the light transmittance T2 after heating, which was then calculated using the following formula. Change in light transmittance after heating (125℃, 168 hours) (%) =(T1-T2) / T1×100

[0127] The cured (α) obtained by the resin composition for the lens in this embodiment under the stated conditions preferably satisfies the necessary conditions (A) to (D) below. (A) The hardening shrinkage rate of the hardened material is more than 1.0% and less than 5.0%. (B) The refractive index of the hardened material is 1.57 or higher. (C) The light transmittance in the thickness direction of the hardened material is 80% or more. (D) The rate of change of light transmittance in the thickness direction of the hardened material after heating (125°C, 168 hours) is less than 10%. By making the lens hardener (α) satisfy the necessary conditions (A) to (D), a lens with dimensional accuracy, optical properties, transparency and heat resistance can be manufactured.

[0128] <Application> The resin composition for the lens in this embodiment is preferably used as a wafer-level lens.

[0129] A wafer-level lens is a lens manufactured by simultaneously fabricating multiple lenses on a wafer-shaped resin (wafer-level lens array) and then cutting it into sections. Figure 1 is a plan view showing an example of the structure of a wafer-level lens array having multiple wafer-level lenses. As shown in Figure 1, the wafer-level lens array 1 includes a substrate 2 and multiple lenses 10 arranged on the substrate 2. The multiple lenses 10 are formed in a one-dimensional or two-dimensional arrangement relative to the substrate 2. The lenses 10 formed on the wafer-level lens array 1 are then diced one by one.

[0130] Therefore, wafer-level lenses can produce hundreds of lenses at a time, offering the advantage of excellent production efficiency.

[0131] Furthermore, wafer-level lenses also possess the advantage of being able to fabricate lenses that are thin and small, even when injection molding has limitations. Wafer-level lenses typically have a diameter of approximately 1 mm to 10 mm and a thickness of approximately 100 μm to 2000 μm. Utilizing these dimensions effectively, wafer-level lenses are ideally suited for use in cameras of electronic devices such as smartphones, tablets, and laptops.

[0132] The resin composition for lenses in this embodiment can form a hardened lens material that combines low curing shrinkage, high refractive index, high light transmittance, and high heat resistance, and is therefore better suited for use in wafer-level lenses that are thin and small.

[0133] [Hardened material for lenses] The hardened lens material of this embodiment can be obtained by hardening the lens resin composition.

[0134] The curing shrinkage rate of the lens curing material in this embodiment is preferably 1.0% or more and 5.0% or less, more preferably 1.2% or more and 4.0% or less, and even more preferably 1.5% or more and 3.0% or less. The curing shrinkage rate can be determined according to the procedure described in the procedure for measuring the curing shrinkage rate of the lens curing material (α).

[0135] The refractive index of the lens hardener in this embodiment is preferably 1.57 or higher, more preferably 1.58 or higher, and even more preferably 1.59 or higher. The refractive index can be determined according to the procedure described herein as a procedure for measuring the refractive index of the lens hardener (α).

[0136] In this embodiment, the light transmittance in the thickness direction of the hardened material for the lens is preferably 80% or more. The light transmittance can be determined according to the procedure described in the procedure for measuring the light transmittance of the hardened material (α) for the lens.

[0137] The rate of change of light transmittance in the thickness direction of the lens curing material in this embodiment after heating (125°C, 168 hours) is preferably 10% or less, more preferably 5% or less, and even more preferably 2% or less. The rate of change of light transmittance after heating (125°C, 168 hours) can be determined according to the procedure described in the measurement procedure for the rate of change of light transmittance after heating (125°C, 168 hours) of the lens curing material (α).

[0138] The lens curing material of this embodiment has low curing shrinkage, high refractive index, high light transmittance and high heat resistance, and is therefore better suited for thin and small wafer-level lenses.

[0139] [lens] The lens in this embodiment includes the aforementioned hardened material for lenses.

[0140] The lens of this embodiment can be manufactured, for example, by imprinting. Imprinting refers to a processing technique in which a lens resin composition is held in a lens molding mold and a pattern is transferred onto it. The lens resin composition held in the lens molding mold is hardened by heating or light irradiation.

[0141] Light irradiation can be carried out in the following ways: using mercury lamps, xenon lamps, carbon arc lamps, metal halide lamps, sunlight, electron beam sources, laser sources, light emitting diode (LED) sources, etc., with a cumulative irradiation dose in the range of, for example, 500 mJ / cm2 to 5000 mJ / cm2.

[0142] Lens resin compositions (lens hardeners) that are clamped and hardened by lens forming molds are sometimes used directly as lenses, but sometimes lens hardeners are laminated with other materials. Examples of other materials used in lens curing lamination include glass. A wide variety of glass is available, with high-refractive-index glass being a suitable raw material for lenses requiring high optical properties. Furthermore, glass also possesses excellent heat resistance. Alternatively, resin can be used. Resin has excellent processability and is suitable for forming lenses simply and inexpensively.

[0143] Furthermore, when using a wafer-level forming mold as a lens forming mold, a wafer-level lens array is obtained, and lenses are obtained by dicing the obtained wafer-level lens array one by one. The wafer-level lens array is as described above.

[0144] The lens of this embodiment combines low hardening shrinkage, high refractive index, high light transmittance, and high heat resistance, making it ideal for use as a wafer-level lens in pursuit of thinness and small size.

[0145] The diameter of a wafer-level lens is typically 1 mm to 10 mm, preferably 1 mm to 5 mm. Additionally, the thickness of a wafer-level lens is typically 100 μm to 2000 μm, preferably 100 μm to 1000 μm.

[0146] Wafer-scale lenses are ideal for use in cameras of electronic devices such as smartphones, tablets, and laptops.

[0147] The embodiments of the present invention have been described above, but these are merely examples of the present invention, and various other structures may also be used. Furthermore, the present invention is not limited to the described embodiments, and variations and improvements within the scope of achieving the purpose of the present invention are included in the present invention. [Example]

[0148] The embodiments of the present invention will be described in detail below, but the embodiments of the present invention are not limited to these embodiments.

[0149] <Fabrication of Resin Components for Lenses>

[0150] The raw materials listed in Table 1 are heated and stirred at 50°C until homogeneous, thereby obtaining a resin composition for lenses.

[0151] The raw materials listed in Table 1 are as follows.

[0152] • Photocationic polymerization initiator (X) Triarylstrom-tetrafluorophenyl gallate, manufactured by San-Apro Co., Ltd., product name: CPI-310FG

[0153] Other photocationic polymerization initiators The following formula represents a photocationic polymerization initiator manufactured by San-Apro Co., Ltd., product name: CPI-210S

[0154] [Chemistry 15]

[0155] ·Epoxy compound(Y) Bisphenol A type epoxy resin, manufactured by DIC Corporation, product name: EXA-850CRP, epoxy equivalent: 158 g / eq~168 g / eq

[0156] • Monofunctional epoxy compounds (Z) o-Phenylphenol glycidyl ether, manufactured by Yokkaichi Synthetic Co., Ltd., product name: OPP-EP

[0157] · Oxycyclic butane compounds (W) Biphenyl-type oxetane compounds, xylyldioxetane, manufactured by Dong-A Synthetic Co., Ltd., product name: Aron Oxetane (OXT-121)

[0158] Adhesion-giving agent Silane coupling agent, 3-glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Industry Co., Ltd., product name: KBM-403

[0159] Antioxidants Phenolic antioxidant, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by Adeka Co., Ltd., product name: Adekastab AO-60

[0160] Light stabilizers Hindered amine light stabilizer, bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacic acid, manufactured by ADEKA Corporation, product name: Adekastab LA-72

[0161] <Viscosity> The viscosity of the resin composition for lenses was measured using a Type E viscometer (TVE-25L, manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25°C and a rotation speed of 2.5 rpm. The cone plate was appropriately selected from 1˚34'×R24, 3˚×R14, and 3˚×R9.7 based on the sample viscosity. The results are shown in Table 1.

[0162] <Fabrication of Hardened Materials for Lenses> A glass substrate (9.0×10.0×0.7 mm, Eagle-XG, manufactured by Corning) was immersed in Novec 1720 (a fluorinated silane release agent, manufactured by 3M Corporation) under nitrogen atmosphere and heated at 100°C for 25 minutes. The substrate was then rinsed with Novec 7100 (a fluorinated solvent, manufactured by 3M Corporation) to obtain a glass substrate that had undergone the release process. A lens resin composition was dropped onto a glass substrate after the molding process was completed. A silicone spacer with a thickness of 250 μm was used to hold the substrate in place and fixed with a fixture. To this end, UV exposure was performed using an electrodeless lamp (H-bulb) at a wavelength of 365 nm with an irradiation intensity of 150 mW / cm and a cumulative irradiation dose of 3000 mJ / cm² to harden the lens resin composition. Subsequently, the hardened resin composition for the lens is demolded from the glass substrate and heated at 120°C for 30 minutes in a nitrogen atmosphere to obtain the hardened lens.

[0163] <Hardening Shrinkage Rate> First, the specific gravity d1 of the resin composition for the lens is determined according to JIS Z 8804:2012 (Method for determination of density and specific gravity of liquids). (Furthermore, in the case where the resin composition for the lens contains volatile components, the specific gravity of the non-volatile components after removing the volatile components is determined, but the resin composition in this embodiment does not contain volatile components.) Subsequently, the specific gravity d² of the hardened material for lenses was determined according to JIS Z 8807:2012 (Methods for Determination of Density and Specific Gravity of Solids). Using the determined specific gravity value, the hardening shrinkage rate was calculated by the following formula. The results are shown in Table 1. Hardening shrinkage rate (%) = (1 - d1 / d2) × 100

[0164] <Determination of Refractive Index> The refractive index of the hardened material for the lens was determined using an Abbe refractometer (DR-M2, manufactured by Atago Inc.). An RE-3520 (589 nm, D-ray, manufactured by Atago Inc.) was used as the interference filter, and RE-1196 (monobromonaphthalene, manufactured by Atago Inc.) was used as the intermediate solution. The sample temperature was set to 25°C. The results are shown in Table 1.

[0165] <Light transmittance> The light transmittance T1 is obtained by measuring the light transmittance in the thickness direction of the hardened material used for the lens under the following conditions. Furthermore, the measurement is performed by attaching the hardened material for the lens to an integrating sphere, with the incident surface set as an arbitrary surface. (Measurement conditions) Measurement apparatus: UH4150 (Ultraviolet-Vis-Near Infrared Spectrophotometer manufactured by Hitachi High-Tech Science Co., Ltd.) Measurement method: Permeation method Measurement wavelength: 400 nm Reference Standard: Atmosphere Detector: Integrating sphere / Photomultiplier tube (200 nm~850 nm) Integrating sphere: PbS (850 nm~2600 nm)

[0166] <Change in light transmittance after heating (125℃, 168 hours)> First, the lens curing material was heated in an oven set at 125°C in air for 168 hours. Then, the light transmittance in the thickness direction was measured under the stated conditions to obtain the light transmittance T2 after heating, which was calculated using the following formula. The results are shown in Table 1. Change in light transmittance after heating (125℃, 168 hours) (%) =(T1-T2) / T1×100

[0167] <Evaluation of Glass Adhesion> A glass substrate (7.0×7.0×0.21 mm, D263T ECO, manufactured by Schott) was immersed in Novec 1720 (fluorinated silane release agent, manufactured by 3M Corporation) under nitrogen atmosphere and heated at 100°C for 25 minutes. The substrate was then rinsed with Novec 7100 (fluorinated solvent, manufactured by 3M Corporation) to obtain a glass substrate that had undergone the release process. A lens resin composition is dropped onto a glass substrate that has undergone demolding. A silicone spacer with a thickness of 250 μm is held in place by a glass substrate that has not undergone demolding (7.0 × 7.0 × 0.21 mm, D263T ECO, manufactured by Schott). The substrate is then secured with a clamp. The amount of lens resin composition dropped is adjusted to ensure that the diameter of the wetting and spreading resin composition is approximately 5 mm. To address this, an electrodeless lamp (H-bulb) was used to perform UV exposure at a wavelength of 365 nm with an irradiation intensity of 150 mW / cm and a cumulative irradiation dose of 3000 mJ / cm², thereby curing the lens resin composition. Subsequently, the self-cured lens resin composition was demolded from the demolded glass substrate and heated at 120°C for 30 minutes under nitrogen atmosphere to obtain a laminate (resin diameter 5 mm) of the cured lens composition and the glass substrate. In addition, except for adjusting the amount of resin composition added to the lens to make the diameter of the resin composition 40 mm, a laminate of the lens curing material and the glass substrate (resin diameter 40 mm) is obtained by the same operation as described above. At this point, the laminate was evaluated as follows: A) no delamination was observed at the interface between the hardened material for the lens and the glass substrate; B) no delamination occurred but the glass substrate was significantly deformed; and C) the resin easily peeled off from the substrate. The results are shown in Table 1.

[0168] [Table 1] Table 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Comparative Example 1 Photocationic polymerization initiator (X) Quality 1 1 1 1 1 3 3 3 Other photocationic polymerization initiators Quality 1 Epoxy compound(Y) Quality 100 50 100 60 60 90 80 55 100 Monofunctional epoxy compounds (Z) Quality 50 40 40 20 40 Oxycyclic butane compounds (W) Quality 10 5 Adhesion giver Quality 1 1 1 1 1 antioxidants Quality 0.5 0.5 0.5 0.5 0.5 Light stabilizer Quality 0.1 0.1 0.1 0.1 0.1 Viscosity (25℃) mPa·s 4000 800 4000 1200 1200 1000 3000 1100 4000 Hardening shrinkage rate % 1.8 3.0 1.9 2.8 2.7 2.1 2.2 2.6 2.0 Refractive index - 1.59 1.60 1.59 1.60 1.60 1.59 1.59 1.60 1.59 Light transmittance % 80.5 83.6 82.9 83.4 842 82.0 82.1 83.9 80.0 Change in light transmittance after heating (125℃, 168 hours) % 4 2 3 2 1 1 2 1 80 Glass adhesion Laminated body (resin diameter 5 mm) A~C A A A A A A A A A Laminated body (resin diameter 40 mm) A~C B A A A A A A A B

[0169] Compared to the comparative example, the rate of change in light transmittance after heating was reduced in the embodiment. This means that coloration caused by heating was suppressed. Furthermore, the curing shrinkage, refractive index, and light transmittance of the embodiment were at a high level comparable to those of the comparative example. Therefore, the resin composition for the lens of this embodiment possesses low curing shrinkage, high refractive index, high light transmittance, and high heat resistance.

[0170] Furthermore, comparisons between the examples show that glass adhesion is improved when one or more of the group consisting of monofunctional epoxy compounds (Z), oxetane compounds, and adhesion promoters are included.

[0171] This application claims priority based on Japanese Patent Application No. 2022-000161, filed on January 4, 2022, the entire contents of which are incorporated herein by reference.

[0172] 1: Wafer Lens Array 2:Substrate 10: Lens

Claims

1. A lens resin composition comprising: a photocationic polymerization initiator (X) composed of a gallate, wherein the gallate is a salt formed by an anion and a cation represented by general formula (1); and an epoxy compound (Y) containing two or more epoxy groups in the molecule, wherein the epoxy compound (Y) is represented by general formula (2), wherein the lens resin composition is coated on a glass plate with a thickness of 250 μm, exposed to ultraviolet light at a wavelength of 365 nm, an irradiation intensity of 150 mW / cm, and a cumulative irradiation dose of 3000 mJ / cm2, and heated at 120°C for 30 minutes under a nitrogen atmosphere to obtain a hardened material that satisfies the necessary condition (B) below, wherein (B) the refractive index of the hardened material is 1.57 or higher; In general formula (1), R1 to R4 independently represent alkyl groups having 1 to 18 carbon atoms or aryl groups having 6 to 14 carbon atoms, and in general formula (2), R5, R6, R8 and R9 independently represent hydrogen atoms, alkyl groups with 1 to 4 carbon atoms or trifluoromethyl groups, respectively; R7 independently represents hydrogen atoms or glycidyl groups, respectively; n is the average number of repetitions and represents a real number in the range of 0 to 30.

2. A resin composition for a lens, comprising: a photocationic polymerization initiator (X) comprising a salt formed by an anion and a cation represented by general formula (1); an epoxy compound (Y) containing two or more epoxy groups in the molecule, said epoxy compound (Y) being represented by general formula (2); and a monofunctional epoxy compound (Z) represented by general formula (5), wherein the content of the photocationic polymerization initiator (X) is preferably 0.05 to 15 parts by mass relative to 100 parts by mass of said epoxy compound (Y), and the content of the monofunctional epoxy compound (Z) is preferably 1 to 200 parts by mass relative to 100 parts by mass of said epoxy compound (Y), wherein in general formula (1), R1 to R4 independently represent an alkyl group having 1 to 18 carbon atoms or an aryl group having 6 to 14 carbon atoms, and in general formula (2), R5, R6, R8 and R9 independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or a trifluoromethyl group, respectively. R7 represents a hydrogen atom or a glycidyl group independently, n is the average number of repetitions and represents a real number in the range of 0 to 30. In general formula (5), A is selected from single bond, oxygen atom, sulfur atom, R10 is an alkyl group with 1 to 8 carbon atoms, and any methylene group can be substituted by an oxygen atom.

3. The resin composition for a lens as described in claim 1 or claim 2, wherein, The epoxy compound (Y) has an epoxy equivalent of 100 g / eq or more and 200 g / eq or less.

4. The resin composition for a lens as described in claim 1 or claim 2, wherein, The content of the epoxy compound (Y) in the non-volatile components of the resin composition for the lens is 40% by mass or more.

5. The resin composition for a lens as described in claim 1 or claim 2, wherein, The photocationic polymerization initiator (X) includes an anion represented by either formula (3) or formula (4) as the anion.

6. The resin composition for a lens as described in claim 1 or claim 2, wherein, The photocationic polymerization initiator (X) contains strontium ions as cations.

7. The resin composition for a lens as described in claim 1, wherein, The resin composition for the lens further includes a monofunctional epoxy compound (Z) represented by general formula (5), in which A is selected from single bonds, oxygen atoms, and sulfur atoms, R10 is an alkyl group having 1 to 8 carbon atoms, and any methylene group may be substituted with an oxygen atom.

8. The resin composition for a lens as described in claim 2 or claim 7, wherein, The monofunctional epoxy compound (Z) is o-phenylphenol glycidyl ether.

9. The resin composition for a lens as described in claim 1 or claim 2, wherein, The resin composition for the lens further includes an oxobutane compound (W).

10. The resin composition for a lens as described in claim 9, wherein, The oxetane compound (W) is a biphenyl-type oxetane compound.

11. The resin composition for a lens as described in claim 1 or claim 2, wherein, The viscosity of the resin composition for the lens, measured using an E-type viscometer at a temperature of 25°C and a rotation speed of 2.5 rpm, is ≥100 mPa·s and ≤5000 mPa·s.

12. The resin composition for a lens as described in claim 2, wherein, The resin composition for the lens is coated on a glass plate with a thickness of 250 μm. It is then exposed to ultraviolet light at a wavelength of 365 nm, an irradiation intensity of 150 mW / cm, and a cumulative irradiation dose of 3000 mJ / cm². The resulting hardened material is heated at 120°C for 30 minutes under a nitrogen atmosphere, satisfying the necessary conditions (A) to (D) below: (A) The hardening shrinkage rate of the hardened material is 1.0% or more and 5.0% or less; (B) The refractive index of the hardened material is 1.57 or more; (C) The light transmittance in the thickness direction of the hardened material is 80% or more; (D) The rate of change of the light transmittance in the thickness direction of the hardened material after heating (125°C, 168 hours) is 10% or less.

13. The resin composition for a lens as described in claim 1 or claim 2, wherein, The resin composition for lenses is used in wafer-level lenses.

14. A hardened material for a lens, obtained by hardening a lens resin composition as described in any one of claims 1 to 13.

15. A lens comprising a lens hardener as described in claim 14.

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