Photocurable resin composition and optical material

Abstract

To provide a photocurable resin composition that exhibits superior photocurability and transparency even when a UV-LED is used as a light source for light irradiation.SOLUTION: A photocurable resin composition contains a photoacid generator with the following properties (i) and (ii). (i) The absorbance at a wavelength of 365 nm at 25°C, measured at a concentration of 2.5 mmol / L, is 0.11 or more. (ii) The molecular weight is 600 or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a photocurable resin composition and an optical material. [Background technology]

[0002] 2. Description of the Related Art Conventionally, photocurable resin compositions (photocurable resin compositions) have been widely used in optical applications such as displays, adhesives for optical semiconductors, lenses, and protective films.

[0003] For example, Patent Document 1 describes a sheet made of a photocurable resin composition that contains a solid epoxy resin, a liquid epoxy resin, and a photoacid generator and has excellent transparency, heat resistance, and the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2015-96571 A Summary of the Invention [Problem to be solved by the invention]

[0005] As a result of intensive research by the present inventors, it was newly discovered that, although the sheet made of the photocurable resin composition described in Patent Document 1 can be photocured when a high-pressure mercury lamp, halogen lamp, xenon lamp, etc. that have traditionally been used as a light source for light irradiation are used, sufficient photocuring cannot be achieved when a UV-LED is used. An object of the present invention is to provide a photocurable resin composition that has excellent photocurability and transparency even when a UV-LED is used as a light source for light irradiation. [Means for solving the problem]

[0006] As a result of intensive research into the above-mentioned problem newly discovered by the inventors, the inventors discovered that by using a specific photoacid generator, it is possible to provide a photocurable resin composition having excellent photocurability and transparency even when a UV-LED is used as a light source for light irradiation, and thus completed the present invention. That is, the present invention (1) relates to a photocurable resin composition containing a photoacid generator having the following characteristics (i) and (ii): (i) The absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L is 0.11 or more. (ii) Molecular weight of 600 or more

[0007] The present invention (2) relates to the photocurable resin composition according to the present invention (1), in which the photoacid generator is a sulfonium salt-based photoacid generator.

[0008] In the present invention (3), the molecular volume of the anion component of the photoacid generator based on Gaussian is 85 Å. 3 The present invention relates to the photocurable resin composition according to the above aspect (1) or (2).

[0009] The present invention (4) relates to a photocurable resin composition according to any one of the present inventions (1) to (3), which contains, as a main component, at least one selected from the group consisting of a phenoxy resin containing an epoxy group, an epoxy resin containing an epoxy group, and a poly(meth)acrylic resin containing an epoxy group.

[0010] The present invention (5) relates to the photocurable resin composition according to any one of the present inventions (1) to (4), which does not contain a low-boiling point component having a boiling point of 100° C. or lower as a main component.

[0011] The present invention (6) relates to the photocurable resin composition according to any one of the present inventions (1) to (5), wherein the content of the resin having a silicone skeleton is 20 mass % or less relative to 100 mass % of the main component.

[0012] The present invention (7) relates to the photocurable resin composition according to any one of the present inventions (1) to (6), which has a storage modulus G' at 50° C. measured with a rheometer of 0.5 MPa or less and is in the form of a film.

[0013] The present invention (8) relates to the photocurable resin composition according to any one of the present inventions (1) to (7), wherein the cured product has a light transmittance of 70% or more at a wavelength of 400 nm at 25°C.

[0014] The present invention (9) also relates to an optical material obtained by curing the photocurable resin composition according to any one of the present inventions (1) to (8). Effect of the Invention

[0015] The photocurable resin composition of the present invention is a photocurable resin composition containing a specific photoacid generator, and therefore has excellent photocurability and transparency even when a UV-LED is used as a light source for light irradiation. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Photocurable resin composition> The photocurable resin composition of the present invention contains a photoacid generator having the following properties (i) and (ii), which ensures excellent photocurability and transparency even when a UV-LED is used as a light source for light irradiation. (i) The absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L is 0.11 or more. (ii) Molecular weight of 600 or more

[0017] The reason why the above-mentioned effects can be obtained with the above-mentioned composition is presumed to be as follows. The characteristic (i) means that the absorbance is equal to or greater than a specific value at a wavelength of 365 nm, which is the wavelength region of light emitted by a UV-LED, and therefore a photoacid generator having the characteristic (i) is capable of generating acid when exposed to light emitted by a UV-LED, resulting in excellent photocurability even when a UV-LED is used as the light source for light irradiation. Furthermore, the specific photoacid generator of the present application has a molecular weight of 600 or more (characteristic (ii)), which is a relatively large molecular weight. When the molecular weight of a photoacid generator is small, the molecules remaining after acid generation are likely to recombine to form a conjugated structure in the composition due to high molecular mobility in the resin, and there is a risk of reducing transparency. However, since the specific photoacid generator of the present application has a relatively large molecular weight, the formation of the conjugated structure can be suppressed, resulting in excellent transparency. Furthermore, a larger molecular weight results in lower diffusibility in the resin, suppressing recombination of residual components after acid generation, making it less likely to cause coloring, resulting in excellent transparency.

[0018] In this specification, when a numerical range is indicated by the symbol "-", such as 50 to 100% by mass, the upper and lower limits are included. For example, 50 to 100% by mass means 50% by mass or more and 100% by mass or less.

[0019] <<Photoacid generator>> The photoacid generator used in the present invention has the following characteristics (i) and (ii): The photoacid generators may be used alone or in combination of two or more kinds. (i) The absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L is 0.11 or more. (ii) Molecular weight of 600 or more

[0020] The absorbance at a wavelength of 365 nm measured at 25°C at a concentration of 2.5 mmol / L is 0.11 or more, preferably 0.15 or more, more preferably 0.30 or more, even more preferably 0.70 or more, particularly preferably 1.00 or more, and most preferably 1.45 or more, with no particular upper limit. In this specification, the absorbance is measured using a spectrophotometer for a solution in which the photoacid generator is diluted with acetonitrile to a concentration of 2.5 mmol / L.

[0021] The molecular weight of the photoacid generator is 600 or more, preferably 650 or more, more preferably 700 or more, even more preferably 800 or more, particularly preferably 900 or more, and most preferably 1000 or more, with no particular upper limit. In this specification, the molecular weight of the photoacid generator is a value calculated from the molecular structure of the compound, which is determined by NMR.

[0022] The photoacid generator may be an onium salt consisting of an anion component and a cation component. As the onium salt, a sulfonium salt is preferable. Examples of the onium cation component include aromatic diazonium, aromatic sulfonium, aromatic iodonium, aromatic selenium, aromatic pyridinium, aromatic ferrocenium, and aromatic phosphonium. These may be used alone or in combination of two or more. Among them, aromatic sulfonium is preferred.

[0023] The anion component is, for example, PF 6 - , P.F. 4 (CF 2 CF 3 ) 2 - , P.F. 3 (CF 2 CF 3 ) 3 - , SbF 6 - , AsF 6 - , SbCl 6 - , BiCl 5 - , SnCl 6 - , ClO 4 - , dithiocarbamate anion, SCN - , trifluoromethanesulfonate, (Rf) n PF 6-n , B(C 6 F 5 ) 4 - , B.F. 4 - , C.F. 3 SO 3 - , S.O. 4 2-and the like represented by the following formula (I). These may be used alone or in combination of two or more kinds. [(R1)(R2)(R3)(R4)Ga]-H + (I) [In formula (1), R1 to R4 each independently represent a phenyl group or a perfluoroalkyl group which may be substituted with a group selected from the group consisting of a perfluoroalkyl group, a perfluoroalkoxy group, a nitro group, a cyano group, an acyl group, and a halogen.] Among them, (Rf) n PF 6-n , B(C 6 F 5 ) 4 - , SbF 6 - , P.F. 4 (CF 2 CF 3 ) 2 - , P.F. 3 (CF 2 CF 3 ) 3 - , P.F. 6 - , SbF 6 - , AsF 6 - , gallate acid type (component represented by the above formula (I)) is preferred, and SbF 6 - , gallate acid type (component represented by the above formula (I)), PF 4 (CF 2 CF 3 ) 2 - , P.F. 3 (CF 2 CF 3 ) 3 - More preferably, SbF 6 - , Ga(C 6 F 5 ) 4 - , P.F. 4 (CF 2 CF 3 ) 2 - , P.F.3 (CF 2 CF 3 ) 3 - is more preferred.

[0024] The Gaussian-based molecular volume of the anion component is preferably 85 Å 3 More preferably, 275 Å or more 3 More preferably, 350 Å or more 3 More preferably, 460 Å or more 3 More than 500 Å, most preferably 3 The upper limit is not particularly limited. In this specification, the molecular volume based on Gaussian of the anion component is calculated using Gaussian, a general-purpose quantum chemical calculation program. For example, PF 6 - , SbF 6 - , P.F. 3 (CF 2 CF 3 ) 3 - The Gaussian-based molecular volumes of 3 , 85 Å 3 , 279 Å 3 It is.

[0025] The photoacid generator used in the present invention has the above-mentioned properties (i) and (ii). A photoacid generator having the above characteristic (i) is selected by introducing a structure into the cationic component that has a higher light absorption in the target wavelength region. In the case of a photoacid generator having the above characteristic (ii), the combination of the cationic component and the anionic component may be appropriately adjusted in consideration of the molecular weights of the cationic component and the anionic component. In accordance with the above guidelines, a person skilled in the art can understand what kind of photoacid generator has the properties (i) and (ii) described above. Therefore, it is possible to obtain a photoacid generator having the properties (i) and (ii) described above from among commercially available photoacid generators, and it is also possible to produce a photoacid generator having the properties (i) and (ii) described above by appropriately combining cationic components and anionic components.

[0026] In the photocurable resin composition of the present invention, the content of the photoacid generator having the above characteristics (i) and (ii) is preferably 0.5 to 5.0 parts by mass, more preferably 0.5 to 4.0 parts by mass, and even more preferably 1.0 to 4.0 parts by mass, based on 100 parts by mass of the main component (resin). This tends to more suitably obtain the effects of the present invention.

[0027] The photocurable resin composition of the present invention may contain a photoacid generator other than the photoacid generator having the above characteristics (i) and (ii), but the content of the photoacid generator having the above characteristics (i) and (ii) in 100% by mass of the photoacid generator is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, particularly preferably 98% by mass or more, and may be 100% by mass. This tends to more suitably obtain the effects of the present invention.

[0028] <<Main component (resin)>> The main component means the component with the highest content in the composition, and is usually a resin. Here, when the composition contains a solvent, the main component means the component with the highest content among the components excluding the solvent. The solvent is a component added to improve coatability, etc., and is ultimately removed by drying.

[0029] The main component is not particularly limited, but is preferably a resin, more preferably a resin having an epoxy group. The resin may be used alone or in combination of two or more kinds. As the epoxy group, an aliphatic epoxy group is preferable, and a glycidyl group is more preferable.

[0030] Examples of the main component (resin) include phenoxy resins containing epoxy groups, epoxy resins containing epoxy groups, poly(meth)acrylic resins containing epoxy groups, oxetane resins, and silicone-containing resins. These may be used alone or in combination of two or more. Among them, phenoxy resins containing epoxy groups, epoxy resins containing epoxy groups, and poly(meth)acrylic resins containing epoxy groups are preferred, phenoxy resins containing epoxy groups, and epoxy resins containing epoxy groups are more preferred, and the combined use of phenoxy resins containing epoxy groups and epoxy resins containing epoxy groups is even more preferred. The phenoxy resins containing epoxy groups and epoxy resins containing epoxy groups tend to improve crosslink density, obtain a cured product with a higher glass temperature, and improve reliability.

[0031] The epoxy functional group equivalent of the resin is not particularly limited, but is preferably 100 to 15,000 g / eq. When the epoxy functional group equivalent is within the above range, the density of the epoxy group is in an appropriate range, and the effects of the present invention tend to be more favorably obtained. In this specification, the epoxy functional group equivalent of a resin is measured in accordance with JIS K7236 (2001).

[0032] The weight average molecular weight of the resin is not particularly limited, but is preferably from 250 to 60,000. Within this range, the reactivity to light is good, and the Tg after curing is high and the heat resistance is good. In this specification, the weight average molecular weight of a resin is a value determined by dissolving the resin in tetrahydrofuran, measuring the molecular weight using a GPC apparatus (HLC-8320GPC, manufactured by Tosoh Corporation) under the following conditions, and converting the molecular weight into polystyrene equivalent value. Column: TSKgel Super HZMH / HZ4000 / HZ3000 / HZ2000 Column size: 6.0mm I.D. x 150mm Eluent:THF Flow rate: 0.6mL / min Detector: RI Column temperature: 40℃ Injection volume: 20μL

[0033] The resin may be in a solid or liquid state at 25°C. In this specification, "solid at 25° C." means a state in which fluidity has been lost at 25° C. and includes a semi-solid state that has no fluidity, and "liquid at 25° C." means a state in which fluidity is maintained at 25° C. In addition, in this specification, "solid resin" means a resin that is solid at 25° C., and "liquid resin" means a resin that is liquid at 25° C.

[0034] The photocurable resin composition of the present invention preferably uses a solid resin and a liquid resin in combination, which tends to provide a film with excellent flexibility, more favorably maintain a film shape, more favorably suppress an excessive increase in tackiness, and provide better handleability. The content of the solid resin in 100% by mass of the main component (resin) is preferably 50 to 90% by mass, and more preferably 50 to 75% by mass, which tends to make it possible to more suitably obtain the above-mentioned effects. The content of the liquid resin (preferably liquid epoxy resin) in 100% by mass of the main component (resin) is preferably 10 to 50% by mass, and more preferably 25 to 50% by mass, which tends to make it possible to more suitably obtain the above-mentioned effects.

[0035] When the photocurable resin composition of the present invention contains a solid epoxy resin having an epoxy functional group equivalent of 400 to 1500 g / eq, the content of the solid epoxy resin having an epoxy functional group equivalent of 400 to 1500 g / eq in 100% by mass of the main component (resin) is preferably 20% by mass or less. This tends to improve the flexibility of the film. Furthermore, in this case, it is preferable to use it in combination with a liquid resin. This tends to improve the tackiness. In this case, the content of the liquid resin (preferably a liquid epoxy resin) in 100% by mass of the main component (resin) is preferably 25 to 50% by mass. This tends to better maintain the film shape, better suppress excessive increase in tackiness, and better handleability.

[0036] The phenoxy resin may be, for example, a polyhydroxy polyether polymerized from a bisphenol and epichlorohydrin. The bisphenol may be bisphenol A or bisphenol F, with bisphenol A being preferred from the viewpoints of transparency and heat resistance.

[0037] Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins such as triglycidyl isocyanurate and hydantoin epoxy, water-added bisphenol A type epoxy resins, aliphatic epoxy resins, glycidyl ether type epoxy resins, and cresol novolac type epoxy resins.

[0038] Examples of poly(meth)acrylic resins include polymers obtained by polymerizing (meth)acrylic acid esters as monomers, such as (meth)acrylic acid alkyl esters, (meth)acrylic acid cycloalkyl esters, and (meth)acrylic acid aryl esters. In this specification, "(meth)acrylic" means "acrylic and / or methacrylic".

[0039] Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, octadecyl (meth)acrylate, and eicosyl (meth)acrylate. Examples of the (meth)acrylic acid cycloalkyl ester include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. Examples of the (meth)acrylic acid aryl ester include phenyl (meth)acrylate, benzyl (meth)acrylate, etc. These (meth)acrylic acid esters may be used alone or in combination of two or more kinds.

[0040] The poly(meth)acrylic resin can also be copolymerized with other monomers that are copolymerizable with the above-mentioned (meth)acrylic acid esters. Examples of the other monomers include carboxyl group-containing monomers, acid anhydride monomers, hydroxyl group-containing monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, acrylamide, acrylonitrile, etc. Examples of the carboxyl group-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Examples of the acid anhydride monomers include maleic anhydride, itaconic anhydride, etc. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)methyl (meth)acrylate. Examples of sulfonic acid group-containing monomers include styrenesulfonic acid, allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, and (meth)acryloyloxynaphthalenesulfonic acid. Examples of phosphoric acid group-containing monomers include 2-hydroxyethyl acryloyl phosphate. These other monomers may be used alone or in combination of two or more.

[0041] The polymerization method for the poly(meth)acrylic resin is not particularly limited, and examples thereof include solution polymerization, emulsion polymerization, suspension polymerization, and bulk polymerization.

[0042] When the resin is a resin that is polymerized by radical polymerization, such as poly(meth)acrylic resin, the method of introducing the epoxy group is not particularly limited, and includes a method of copolymerizing a monomer having an epoxy group with the above-mentioned various monomers, etc. As the epoxy group, an aliphatic epoxy group is preferable, a glycidyl group is more preferable, and a glycidyl (meth)acrylate group is even more preferable.

[0043] Examples of the monomer having an epoxy group include a monomer having an aliphatic epoxy group, a monomer having an alicyclic epoxy group, and a monomer having an aromatic epoxy group. Among these, a monomer having an aliphatic epoxy group is preferred.

[0044] Examples of monomers having an aliphatic epoxy group include glycidyl ethers of polyhydric alcohols such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, triglycidyl ether of glycerin, triglycidyl ether of trimethylolpropane, tetraglycidyl ether of sorbitol, hexaglycidyl ether of dipentaerythritol, diglycidyl ether of polyethylene glycol, and diglycidyl ether of polypropylene glycol; polyglycidyl ethers of polyether polyols obtained by adding one or more alkylene oxides to aliphatic polyhydric alcohols such as propylene glycol, trimethylolpropane, and glycerin; diglycidyl esters of aliphatic long-chain dibasic acids; monoglycidyl ethers of aliphatic higher alcohols; glycidyl esters of higher fatty acids; and (meth)acrylates of aliphatic epoxy compounds such as epoxidized soybean oil, epoxy octyl stearate, epoxy butyl stearate, epoxidized soybean oil, and epoxidized polybutadiene. Specific examples include epoxy group-containing (meth)acrylates such as 4-hydroxybutyl (meth)acrylate glycidyl ether and glycidyl (meth)acrylate.

[0045] Examples of monomers having an alicyclic epoxy group include 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-1-methylcyclohexyl-3,4-epoxy-1-methylhexane carboxylate, 6-methyl-3,4-epoxycyclohexylmethyl-6-methyl-3,4-epoxycyclohexane carboxylate, 3,4-epoxy-3-methylcyclohexylmethyl-3,4-epoxy-3-methylcyclohexane carboxylate, 3,4-epoxy-5-methylcyclohexylmethyl-3,4-epoxy-5-methylcyclohexane carboxylate, bis(3,4-epoxycyclohexyl)methyl-3,4-epoxy-5-methylcyclohexane carboxylate, and bis(3,4-epoxycyclohexyl)methyl-3,4-epoxy-5-methylcyclohexane carboxylate. cycloaliphatic epoxy compounds such as 1,2-dimethylphenyl)adipate, 3,4-epoxy-6-methylcyclohexyl carboxylate, methylene bis(3,4-epoxycyclohexane), propane-2,2-diyl-bis(3,4-epoxycyclohexane), 2,2-bis(3,4-epoxycyclohexyl)propane dicyclopentadiene diepoxide, ethylene bis(3,4-epoxycyclohexane carboxylate), 1-epoxyethyl-3,4-epoxycyclohexane, 1,2-epoxy-2-epoxyethylcyclohexane, caprolactone-modified products, trimethylcaprolactone-modified products, and valerolactone-modified products thereof can be mentioned.

[0046] Examples of monomers having an aromatic epoxy group include (meth)acrylates of aromatic epoxy compounds such as monoglycidyl ethers of polyether alcohols obtained by adding alkylene oxides to phenol, cresol, or butylphenol.

[0047] When the resin is a phenoxy resin, the method for introducing an epoxy group is not particularly limited. For the epoxy group, for example, a method of reacting a hydroxyl group-containing resin with a chloro group-containing epoxy compound such as epichlorohydrin can be mentioned.

[0048] The content of the main component (resin) in 100% by mass of the photocurable resin composition of the present invention (when the composition contains a solvent, the total amount of components other than the solvent is taken as 100% by mass) is preferably 92 to 99% by mass, more preferably 95 to 99% by mass, which tends to more suitably achieve the effects of the present invention.

[0049] The content of the phenoxy resin containing an epoxy group in 100% by mass of the main component (resin) is preferably 20 to 60% by mass, and more preferably 40 to 60% by mass, which tends to make it possible to more suitably obtain the effects of the present invention.

[0050] The content of the epoxy resin containing an epoxy group in 100% by mass of the main component (resin) is preferably 20 to 80% by mass, and more preferably 40 to 60% by mass, which tends to more suitably obtain the effects of the present invention.

[0051] When a resin having a silicone skeleton is contained, transparency tends to decrease, so in the photocurable resin composition of the present invention, the content of the resin having a silicone skeleton in 100 mass% of the main component (resin) is preferably 20 mass% or less, more preferably 10 mass% or less, even more preferably 5 mass% or less, particularly preferably 1 mass% or less, and most preferably 0 mass% (not contained).

[0052] If a low-boiling component with a boiling point of 100°C or less is contained, it may volatilize during coating or drying, and the physical properties may be unstable. In addition, there is a risk of the resin composition overflowing during coating or lamination. Therefore, it is preferable that the main component (resin) does not contain a low-boiling component with a boiling point of 100°C or less. In the photocurable resin composition of the present invention, the content of low-boiling point components having a boiling point of 100°C or less in 100% by mass of the main component (resin) is preferably 0.9% by mass or less, more preferably 0.5% by mass or less, even more preferably 0.1% by mass or less, and particularly preferably 0% by mass (not contained).

[0053] An example of a low-boiling point component having a boiling point of 100° C. or less is a compound having an oxetanyl group. In the present invention, even if the photocurable resin composition does not contain a low-boiling point component having a boiling point of 100° C. or less such as a compound having an oxetanyl group, it contains a specific photoacid generator, and therefore has excellent photocurability even when a UV-LED is used as a light source for light irradiation.

[0054] Examples of compounds having an oxetanyl group include 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 3-methyl-3-hydroxymethyloxetane, 3-ethyl-3-hydroxymethyloxetane, 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, di[(3-ethyl-3-oxetanyl)methyl]ether ...1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]ether, 1,4- dimethyl)oxetane, phenol novolak oxetane, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3-oxetanylmethyl) ether, 2-ethylhexyl (3-ethyl-3-oxetanylmethyl) ether, ethyl diethylene glycol (3-ethyl-3-oxetanylmethyl) ether, di[1-ethyl(3-oxetanyl)]methyl ether, 3,7-bis(3-oxetanyl)-5-oxa- Nonane, 1,2-bis[(3-ethyl-3-oxetanylmethoxy)methyl]ethane, 1,3-bis[(3-ethyl-3-oxetanylmethoxy)methyl]propane, ethylene glycol bis(3-ethyl-3-oxetanylmethyl)ether, tricyclodecanediyldimethylene(3-ethyl-3-oxetanylmethyl)ether, trimethylolpropane tris(3-ethyl-3-oxetanylmethyl)ether, 1,4-bis(3-ethyl-3-oxetanylmethoxy)butane, 1,6-bis(3-ethyl-3-oxetanylmethoxy) Examples of the ether include hexane, pentaerythritol tris(3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl) ether, polyethylene glycol bis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol pentakis(3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol tetrakis(3-ethyl-3-oxetanylmethyl) ether, etc. These may be used alone or in combination of two or more.

[0055] The total content of the photoacid generator and the main component (resin) in 100 mass% of the photocurable resin composition of the present invention (when the composition contains a solvent, the total amount of components other than the solvent is taken as 100 mass%) is preferably 90 mass% or more, more preferably 95 mass% or more, even more preferably 98 mass% or more, particularly preferably 99 mass% or more, and may be 100 mass%.

[0056] <<Silane coupling agents>> The photocurable resin composition of the present invention preferably contains a silane coupling agent, which can increase the adhesive strength when the composition is bonded to other substrates such as glass.

[0057] Examples of silane coupling agents include 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropylmethylethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, and 3-mercaptopropyltrimethoxysilane. These can be used alone or in combination of two or more. Among them, silane coupling agents having an epoxy group such as 3-glycidoxypropyltrimethoxysilane are preferred, and 3-glycidoxypropyltrimethoxysilane is more preferred.

[0058] The amount of the silane coupling agent is not particularly limited, but is preferably 0.5 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and even more preferably 0.5 to 2 parts by mass, relative to 100 parts by mass of the main component (resin). This can improve adhesion without deteriorating the optical design or transparency.

[0059] The photocurable resin composition of the present invention may contain other components in addition to the photoacid generator and the main component (resin) as long as the effects of the present invention are not impaired. Examples of other components include photosensitizers. These may be used alone or in combination of two or more.

[0060] Examples of photosensitizers include anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducible dyes, etc. These may be used alone or in combination of two or more. Anthracene compounds, which have excellent photosensitizing effects, are particularly preferred. The content of the photosensitizer is preferably 0.1 to 5 mass%, more preferably 0.5 to 3 mass%, based on 100 mass% of the photocurable resin composition of the present invention (here, when the composition contains a solvent, the total amount of the components other than the solvent is taken as 100 mass%).

[0061] It is preferable that the photocurable resin composition of the present invention does not contain a thermal acid generator containing an aromatic sulfonium salt represented by the following general formula (1), which can provide more excellent transparency and improve long-term storage stability. The content of the thermal acid generator containing an aromatic sulfonium salt represented by the following general formula (1) in 100 mass% of the photocurable resin composition of the present invention (when the composition contains a solvent, the total amount of components other than the solvent is taken as 100 mass%) is preferably 1 mass% or less, more preferably 0.5 mass% or less, even more preferably 0.1 mass% or less, and particularly preferably 0 mass% (not contained). [ka] (In the above general formula (1), R 1 represents a hydrogen atom, a methoxycarbonyl group, an acetyl group, or a benzoyl group, R 2 represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, R 3 represents an alkyl group having 1 to 4 carbon atoms, a benzyl group unsubstituted or substituted with an alkyl group having 1 to 4 carbon atoms, or an α-naphthylmethyl group, R 4 represents an alkyl group having 1 to 4 carbon atoms. X is SbF 6 , P.F. 6 , AsF 6, B.F. 4 , C.F. 3 SO 3 , (CF 3 SO 2 ) 2 N,B(C 6 F 5 ) 4 It indicates either

[0062] The photocurable resin composition of the present invention preferably has a storage modulus G' of 0.5 MPa or less at 50° C. as measured by a rheometer, and is in the form of a film, which tends to provide better tackiness and flexibility. The storage modulus G' at 50° C. measured with a rheometer is more preferably 0.4 MPa or less, and further preferably 0.3 MPa or less, with no particular lower limit. When the photocurable resin composition has a high liquid component ratio, the storage modulus G' tends to be lower.

[0063] The light transmittance (linear transmittance) of the cured product of the photocurable resin composition of the present invention at a wavelength of 400 nm at 25° C. is preferably 70% or more, more preferably 80% or more. There is no particular upper limit, but it is preferably 99% or less. If the light transmittance is less than 70%, the transparency may be insufficient and the product may not be usable for optical purposes. The light transmittance can be measured using a spectrophotometer. By suppressing the light absorption in the ultraviolet region of the raw materials used, the light transmittance at a wavelength of 400 nm can be adjusted to fall within the above numerical range.

[0064] The refractive index of the cured product of the photocurable resin composition of the present invention with respect to light having a wavelength of 589 nm at 25° C. varies depending on the application of the photocurable resin composition. For example, when the photocurable resin composition of the present invention is used for a lens, the refractive index is preferably 1.40 or more, more preferably 1.47 or more. The upper limit is not particularly limited, but is preferably 1.80 or less. The refractive index can be measured using a refractometer. By adjusting the refractive index of the raw materials used and their blending ratio, the refractive index for light with a wavelength of 589 nm can be adjusted to fall within the above numerical range.

[0065] A specific method for adjusting the light transmittance and the refractive index to be within the above numerical ranges may involve, for example, using a material that has low light absorption in the ultraviolet region, and adjusting the amount of a material that has light absorption (e.g., a photoacid generator) to a small amount as necessary.

[0066] The photocurable resin composition in the form of a film (photocurable resin film (sheet)) of the present invention can be produced by casting a photocurable resin composition containing the above-mentioned photoacid generator, main component (resin), and, if necessary, a solvent on a substrate, and drying the solvent if necessary. The photocurable resin composition containing the above-mentioned photoacid generator and main component (resin) can also be processed into a film shape with a roll, or extruded into a film shape from a T-die. If a substrate is used after that, the substrate may or may not be peeled off. In addition, a photocurable resin film produced on a substrate can be further stacked with another substrate to form a photocurable resin film sandwiched between the substrates. In this case, the photocurable resin film can be wound around a core to form a roll. In addition, a film cut to a predetermined size can be stacked to form a sheet film.

[0067] The solvent is not particularly limited, but examples thereof include esters such as ethyl lactate, methyl acetate, and butyl acetate, ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, polar solvents such as dimethylformamide and dimethyl sulfoxide, halogen-based solvents such as 1,1,1-trichloroethane and chloroform, ethers such as tetrahydrofuran and dioxane, aromatics such as benzene, toluene, and xylene, and fluorinated inert liquids such as perfluorooctane and perfluorotri-N-butylamine. These may be used alone or in combination of two or more. Among them, methyl ethyl ketone is preferred from the viewpoint of compatibility with the solute.

[0068] When the photocurable resin composition contains a solvent, the content of the solvent is not particularly limited, but is preferably 20 to 50 parts by mass per 100 parts by mass of the total content of the photoacid generator and the main component (resin).

[0069] The substrate is, for example, a plastic substrate, and a plastic film can be suitably used. The material of the plastic substrate is not particularly limited, but examples thereof include polyolefin, polyester, polyurethane, polycarbonate, polyether ether ketone, polyimide, polyetherimide, polyamide, wholly aromatic polyamide, polyvinyl chloride, polyvinylidene chloride, polyphenyl sulfide, aramid, fluororesin, cellulose-based resin, silicone resin, etc. Examples of polyolefin include low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, very low-density polyethylene, random copolymerized polypropylene, block copolymerized polypropylene, homopolypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer, ionomer resin, ethylene-(meth)acrylic acid copolymer, ethylene-(meth)acrylic acid ester copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, etc. Examples of polyester include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc. These materials may be used alone or in combination of two or more. The substrate may have a single layer structure or a multi-layer structure. Furthermore, the substrate preferably has light transmittance.

[0070] The thickness of the photocurable resin film of the present invention (excluding the substrate) is preferably 10 to 300 μm, more preferably 30 to 100 μm. If the thickness of the photocurable resin film is less than 10 μm, the handling property may be impaired, and if it exceeds 300 μm, the photocurability may be impaired. In the case of a thick film, it is also possible to form it by laminating thin layers one on top of the other.

[0071] The photocurable resin composition of the present invention can be cured by light irradiation such as ultraviolet light (for example, wavelength of about 365 nm). As a light source for light irradiation, an LED, a low pressure mercury lamp, a high pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, etc. can be used. However, since the photocurable resin composition of the present invention is a photocurable resin composition containing a specific photoacid generator, even when a UV-LED is used as a light source for light irradiation, it is preferable to use a UV-LED because it has excellent photocurability and transparency. The amount of irradiation is not particularly limited, but is preferably 100 to 10,000 mJ / cm. 2 It is preferable to carry out a heat curing step as necessary. Heating conditions include, for example, a temperature of 80 to 180° C. for 5 to 60 minutes.

[0072] The optical material of the present invention is characterized in that it is obtained by curing the photocurable resin composition of the present invention. The optical material is not particularly limited, but examples thereof include adhesives for displays and optical semiconductors, lenses, protective films and other optical and electronic components. EXAMPLES

[0073] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified.

[0074] The materials used in the examples and comparative examples are shown below.

[0075] Resin 1 (phenoxy resin having a glycidyl group, Mitsubishi Chemical's 1256B40 (solid content 40 mass%), weight average molecular weight 45,000, epoxy functional group equivalent 7800 g / eq) Resin 2 (phenoxy resin with glycidyl group, YP70 manufactured by Nippon Steel Chemical & Material Co., Ltd., weight average molecular weight 55,000, epoxy functional group equivalent 12,100 g / eq) Resin 3 ((meth)acrylic resin having a glycidyl group (glycidyl (meth)acrylate group), 1HM2067 manufactured by Taisei Fine Chemical Co., Ltd., weight average molecular weight 60,000, epoxy equivalent 433 g / eq) Resin 4 (liquid epoxy resin, JER828 manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 378, epoxy functional group equivalent 189 g / eq) Resin 5 (liquid epoxy resin, JER827 manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 370, epoxy functional group equivalent 185 g / eq) Resin 6 (liquid epoxy resin, Cel2021P manufactured by Daicel Corporation, weight average molecular weight 260, epoxy functional group equivalent 135 g / eq) Resin 7 (solid epoxy resin, Daicel's EHPE3150 (alicyclic epoxy resin), weight average molecular weight 2400, epoxy functional group equivalent 180 g / eq) Resin 8 (solid epoxy resin, EG-200 manufactured by Osaka Gas Chemicals, epoxy functional group equivalent 290 g / eq) Resin 9 (solid epoxy resin, Epokukdo YD-012W (bisphenol A type epoxy resin) manufactured by Kukdo Chemical Co., Ltd., weight average molecular weight 1200, epoxy functional group equivalent 650 g / eq) Resin 10 (solid epoxy resin, YX8040 manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 1200, epoxy functional group equivalent 1100 g / eq) Resin 11 (oxetane resin, OXT221 (oxetanyl group-containing compound, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane), molecular weight 214, manufactured by Toagosei Co., Ltd. Resin 12 (silicone-containing resin, Shin-Etsu Silicone's KR-470 (resin having a silicone skeleton), epoxy functional group equivalent 200 g / eq) Photoacid generator 1 (triarylsulfonium salt, San-Apro Co., Ltd. CPI-310FG, absorbance at 365 nm measured at 25 °C at a concentration of 2.5 mmol / L: 1.46, molecular weight: 1300, anion component: Ga(C 6 F 5 ) 4 - , Gaussian-based molecular volume of the anion component: 514 Å3 ) Photoacid generator 2 (triarylsulfonium salt, San-Apro Co., Ltd. CPI-310A, absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L: 1.45, molecular weight: 757, anion component: SbF 6 - , Gaussian-based molecular volume of the anion component: 85 Å 3 ) Photoacid generator 3 (triarylsulfonium salt, San-Apro Co., Ltd. CPI-200K, absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L: 0.11, molecular weight: 817, anion component: PF 3 (CF 2 CF 3 ) 3 - , Gaussian-based molecular volume of the anion component: 279 Å 3 ) Photoacid generator 4 (triarylsulfonium salt, ADEKA SP-170, absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L: 0.07, molecular weight: 633, anion component: SbF 6 - , Gaussian-based molecular volume of the anion component: 85 Å 3 ) Photoacid generator 5 (triarylsulfonium salt, ADEKA SP-150, absorbance at 365 nm measured at 25°C at a concentration of 2.5 mmol / L: 0.08, molecular weight: 517, anion component: PF 6 - , Gaussian-based molecular volume of the anion component: 75 Å 3 ) Silane coupling agent: Shin-Etsu Silicone's KBM403 (3-glycidoxypropyltrimethoxysilane)

[0076] <Absorbance of photoacid generator> A solution was prepared by diluting the photoacid generator with acetonitrile so that the concentration was 2.5 mmol / L. The absorbance of the prepared solution was evaluated at 25°C from 500 nm to 190 nm using a Jasco spectrophotometer with a 10 mm square quartz glass measurement cell for liquids, and the absorbance value at 365 nm was confirmed.

[0077] Examples and Comparative Examples A photocurable resin composition was obtained by mixing the mixture (mass ratio) shown in Table 1 at 2200 rpm for 5 minutes using a planetary centrifugal mixer, and then degassing the mixture for 1.5 minutes using the planetary centrifugal mixer. At this time, methyl ethyl ketone (MEK) was appropriately added to facilitate coating, and the solid content in the composition was adjusted to 40 to 60 mass%. A PET film was used as a substrate, and a photocurable resin composition was cast onto the substrate and dried to obtain a photocurable resin film having a thickness of 100 μm. The photocurable resin film thus obtained was evaluated by the following methods. The evaluation results are shown in Table 1.

[0078] <Light curing> The photocurable resin films prepared in the examples and comparative examples were evaluated for photocurability under the following conditions using a UV rheometer manufactured by Anton Paar, and G'<G’’からG’> The point where G'' is reached is considered to be sufficient light curing, and the point where G' = G'' (cross point) is considered to be the light curing time. In addition, when acrylic polymer is used, the elastic term is dominant from the beginning, and G'>G'', so in this case, the intersection point between the slope of the initial G' increase and the saturated final G' was analyzed and defined as the cross point. In order to stabilize the measurement, the measurement was performed without light irradiation for 50 seconds after the start of the measurement. Measurement temperature: 40℃ Sample size and thickness: 5mmφ, 100μm Irradiation light: 365 nm single wavelength, 25 mW / cm 2 The curing time was evaluated according to the following criteria. ◎: 200 seconds or less 〇:201~300 seconds △:301~350 seconds ×: longer than 350 seconds

[0079] <Light transmittance> The photocurable resin films obtained in the examples and comparative examples were photocured by irradiating light at a single wavelength of 365 nm to an accumulated irradiation amount of 3 J, and then post-cured (150°C x 30 minutes). The light transmittance (linear transmittance, wavelength 400 nm) of the obtained cured products at 25°C was measured using a spectrophotometer (manufactured by Jasco).

[0080] <Viscosity: Storage modulus G'> The storage modulus G' at 50°C of the photocurable resin films produced in the Examples and Comparative Examples was measured using a rheometer (HAAKE, manufactured by TA Corporation) under the following measurement conditions. The lower the storage modulus G' at 50°C, the better the flexibility of the film. Sample size: diameter 8mmΦ, thickness 100μm Measurement mode: Shear oscillation Frequency: 1Hz

[0081] <Tackiness (sticking ability)> The photocurable resin films prepared in the Examples and Comparative Examples were laminated to a release liner using a laminator at 85° C. This film was laminated to a 0.5 mm thick glass using a laminator at 85° C., and when the release liner on the surface was peeled off from the laminated film, it was confirmed whether the adhesion to the glass was sufficient, and was evaluated according to the following criteria. In the case of a liquid, the composition was dropped onto glass and it was confirmed whether it peeled off after light irradiation. 〇: No peeling or peeling △: Some peeling is observed, peels off easily

[0082] <Refractive index> The photocurable resin films obtained in the examples and comparative examples were photocured by irradiating light at a single wavelength of 365 nm to an integrated irradiation amount of 3 J, and then post-cured (150°C x 30 minutes). The refractive index of the obtained cured product with respect to sodium D line (light with a wavelength of 589 nm) in a 25°C environment was measured using a refractometer (manufactured by Atago Co., Ltd.).

[0083] <Resin overflow during lamination> The photocurable resin films obtained in the Examples and Comparative Examples were cut into 25 mm squares, sandwiched between two pieces of glass of the same size (25 mm x 25 mm), thermocompressed in a vacuum press at 80°C, and then cured in the same manner as in the evaluation of light transmittance. After curing, it was confirmed whether the resin protruded from the edge of the glass, and evaluated according to the following criteria. In the case of the liquid sample, the resin composition was dropped onto one side of glass, and then the other side of glass was placed over it, followed by curing in the same manner as in the case of the film. ○: Protrusion from the edge is within 0 to 1 mm ×: Protrusion from the edge is more than 1 mm or resin is not filled

[0084] [Table 1]

[0085] From Table 1, it was found that the photocurable resin compositions of the examples containing a specific photoacid generator had excellent photocurability and transparency even when a UV-LED was used as a light source for light irradiation. In Comparative Example 2, by increasing the content of the photoacid generator, the photocurability was improved, but the transparency was reduced. [Industrial Applicability]

[0086] The present invention relates to a photocurable resin composition, which can be used for optical and electronic component applications such as adhesives for displays and optical semiconductors, lenses, protective films, etc.

Claims

1. A photocurable resin composition comprising a photoacid generator having the following characteristics (i) and (ii): (i) an absorbance at a wavelength of 365 nm at 25° C. measured at a concentration of 2.5 mmol / L is 0.11 or more; (ii) Molecular weight of 600 or more

2. 2. The photocurable resin composition according to claim 1, wherein the photoacid generator is a sulfonium salt-based photoacid generator.

3. The molecular volume of the anion component of the photoacid generator based on Gaussian is 85 Å. ３ The photocurable resin composition according to claim 1 .

4. 2. The photocurable resin composition according to claim 1, comprising, as a main component, at least one selected from the group consisting of a phenoxy resin containing an epoxy group, an epoxy resin containing an epoxy group, and a poly(meth)acrylic resin containing an epoxy group.

5. 2. The photocurable resin composition according to claim 1, which does not contain a low-boiling point component having a boiling point of 100° C. or less as a main component.

6. 2. The photocurable resin composition according to claim 1, wherein the content of the resin having a silicone skeleton is 20% by mass or less based on 100% by mass of the main component.

7. 2. The photocurable resin composition according to claim 1, which has a storage modulus G' of 0.5 MPa or less at 50° C. as measured by a rheometer, and is in the form of a film.

8. 2. The photocurable resin composition according to claim 1, wherein the cured product has a light transmittance of 70% or more at 25° C. to light having a wavelength of 400 nm.

9. An optical material obtained by curing the photocurable resin composition according to any one of claims 1 to 8.

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