JP2010197692A - Photocurable resin composition for optical member, adhesive, and touch panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable resin composition for optical members, from which an adhesive for optical members having excellent coatability and transparency and almost free from optical strain with a base material and an optical member is obtained; to provide an adhesive obtained by using the composition; and to provide a touch panel obtained by using the adhesive. <P>SOLUTION: The photocurable resin composition contains: a compound having at least one photo-cation polymerizable functional group in the molecule and a viscosity of &le;200 mPa&times;s, as measured by using a cone rotor-type viscometer under conditions of 25&deg;C and 10 rpm; a compound having at least one kind of structure selected from fluorene skeleton, naphthalene skeleton and biphenyl skeleton and an oxetanyl group and/or epoxy group; and a cationic polymerization initiator. The photocurable resin composition has a viscosity of 5-500 mPa&times;s, as measured by using a cone rotor-type viscometer under conditions of 25&deg;C and 10 rpm and provides a cured material having a refractive index of &ge;1.50 when the thickness is 50 &mu;m. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

The present invention relates to a photocurable resin composition for an optical member that is excellent in coatability and transparency, and that can provide an adhesive for an optical member that hardly causes optical distortion with a substrate or an optical member. Moreover, this invention relates to the adhesive agent and touchscreen which use this photocurable resin composition for optical members.

In recent years, input devices having a touch panel function on the surface of a flat panel display such as a liquid crystal display, a plasma display, and an organic EL display have been widely used. For this touch panel, a protective film, an antireflection film, an ITO vapor-deposited resin film, or the like is used.

Various films used for the touch panel are adhered to an adherend with an adhesive. As this adhesive, since it is excellent in transparency, an adhesive mainly composed of an acrylic resin is generally used.
However, an adhesive using an acrylic resin has a problem in that optical distortion occurs because the refractive index is too low as compared with ITO or a base material deposited on the touch panel.

Patent Document 1 discloses an adhesive whose refractive index is improved by blending an aromatic component with the adhesive. However, since the adhesive disclosed in Patent Document 1 needs to copolymerize or contain a large amount of an aromatic component in order to improve the refractive index, the transparency decreases, the temperature There were problems such as coloring due to changes. Further, there is a problem in that the viscosity becomes too high and the coating property is deteriorated.

JP 2003-013029 A

The present invention provides a photocurable resin composition for an optical member that can provide an adhesive for an optical member that is excellent in coating properties and transparency and that hardly causes optical distortion with a substrate or an optical member. For the purpose. Moreover, an object of this invention is to provide the adhesive agent and touchscreen which use this photocurable resin composition for optical members.

The present invention has at least one photocationically polymerizable functional group in the molecule, and has a viscosity of 200 mPa · s or less when measured at 25 ° C. and 10 rpm using a cone rotor viscometer. A cone rotor viscometer comprising a compound, a compound having at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton, and an oxetanyl group and / or an epoxy group, and a cationic polymerization initiator. Photocurability for optical members having a viscosity of 5 to 500 mPa · s when measured at 25 ° C. and 10 rpm, and a refractive index of the cured product of 1.50 or more when the thickness is 50 μm. It is a resin composition.
The present invention is described in detail below.

By using a compound having at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton, and an oxetanyl group and / or an epoxy group, together with a low-viscosity photocationically polymerizable compound. The present inventors have found that an adhesive having a viscosity suitable for coating, excellent transparency, and a cured product having a high refractive index can be obtained, and the present invention has been completed.

The photocurable resin composition for an optical member of the present invention has at least one photocationically polymerizable functional group in the molecule, and was measured using a cone rotor viscometer at 25 ° C. and 10 rpm. A compound having a viscosity of 200 mPa · s or less (hereinafter also referred to as a photocationically polymerizable low-viscosity compound).
Hereinafter, the viscosity in the present specification means a value obtained by measurement under conditions of 25 ° C. and 10 rpm using a cone rotor viscometer.

The photocationically polymerizable low-viscosity compound is not particularly limited as long as it has a viscosity of 200 mPa · s or less and has at least one photocationically polymerizable functional group in the molecule. For example, at least one in the molecule And compounds having an epoxy group, an oxetanyl group, a hydroxyl group, a vinyl ether group, an episulfide group, an ethyleneimine group, and the like. Among them, since it has high photocationic polymerizability and photocuring proceeds efficiently even with a small amount of light, it is a compound having at least one epoxy group in the molecule (hereinafter also referred to as an epoxy compound), or in the molecule. Are preferably compounds having at least one oxetanyl group (hereinafter also referred to as oxetane compounds). However, the photocationically polymerizable low-viscosity compound does not include a compound having at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton described later, and an oxetanyl group and / or an epoxy group.
The polymerization degree of these photocationically polymerizable low-viscosity compounds is not particularly limited, and may be any of a monomer, an oligomer, and a polymer. Moreover, these photocationic polymerizable low-viscosity compounds may be used independently and 2 or more types may be used together.

The epoxy compound is not particularly limited, for example, bisphenol type epoxy resin, novolac type epoxy resin, alcohol type epoxy resin, halogenated epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, Multifunctional epoxy resin, biphenyl type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin rubber modified epoxy resin, urethane modified epoxy resin, epoxidized polybutadiene, epoxidized styrene-butadiene-styrene block Examples thereof include a copolymer, an epoxy group-containing polyester resin, an epoxy group-containing polyurethane resin, and an epoxy group-containing acrylic resin.
The bisphenol type epoxy resin is not particularly limited, and examples thereof include bisphenol A type epoxy resin and bisphenol F type epoxy resin.
The novolac type epoxy resin is not particularly limited, and examples thereof include a phenol novolac type epoxy resin and a cresol novolac type epoxy resin.
The alcohol type epoxy resin is not particularly limited, and examples thereof include hydrogenated bisphenol A type epoxy resin and hydrogenated bisphenol F type epoxy resin.
The halogenated epoxy resin is not particularly limited, and examples thereof include brominated epoxy resins.
These epoxy compounds may be used alone or in combination of two or more.

Examples of commercially available epoxy compounds include Epicoat 806, Epicoat 828, Epicoat 1001, Epicoat 1002, Epicoat YL6753 (all manufactured by Japan Epoxy Resin Co., Ltd.), and Celoxide 2021 (manufactured by Daicel Chemical Industries, Ltd.). Etc.

The oxetane compound is not particularly limited. For example, phenoxymethyl oxetane, 3,3-bis (methoxymethyl) oxetane, 3,3-bis (phenoxymethyl) oxetane, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl-3-hydrosiloxymethyloxetane, 3-ethyl-3-{[3- (triethoxysilyl) propoxy] methyl} oxetane, di [1-ethyl (3-oxetanyl)] methyl ether, oxetanylsilsesquioxy Sun, phenol novolac oxetane, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene and the like. These oxetane compounds may be used alone or in combination of two or more.

As what is marketed among the said oxetane type compounds, Aron oxetane OXT-101, Aron oxetane OXT-221 (all are Toagosei Co., Ltd. product) etc. are mentioned, for example.

Examples of the photocationically polymerizable low-viscosity compound other than the epoxy compound and the oxetane compound include, for example, cyclic ethers, vinyl ethers, vinylamines, unsaturated hydrocarbons, cyclic esters, lactams, cyclic carbonates, Examples include cyclic acetals, aldehydes, cyclic amines, cyclic sulfides, cyclosiloxanes, cyclotriphosphazenes, and compounds having other photocationically polymerizable functional groups. Of these, cyclic ethers, unsaturated hydrocarbons, vinyl ethers, vinylamines and the like are preferable.

The photocationically polymerizable low-viscosity compound preferably has a cycloalkane skeleton.
The photocationically polymerizable low-viscosity compound having a cycloalkane skeleton is not particularly limited as long as it has one or more cycloalkane skeletons in the structure or in the repeating unit, but the cycloalkane skeleton is included in the repeating unit. It is preferable that it is a compound which has. When the compound has a cycloalkane skeleton in the repeating unit, it may be a compound having only one cycloalkane skeleton in the repeating unit, or a compound having two or more.

The photocationically polymerizable low-viscosity compound having a cycloalkane skeleton is not particularly limited as long as it has the above-described structure, but an adhesive using the obtained photocurable resin composition for an optical member is light-resistant. An epoxy compound having at least one structure selected from the group consisting of the following general formulas (1), (2) and (3) because it has excellent heat resistance and excellent adhesion. Preferably there is.

In formula (1), n represents the integer of 0-20. R ¹ and R ² represent hydrogen or a linear or branched alkyl group having 1 to 12 carbon atoms, and R ¹ and R ² may be the same or different from each other. Good.

In formula (2), n represents an integer of 0 to 20. R ^{3 to} R ¹⁰ represent hydrogen or a linear or branched alkyl group having 1 to 12 carbon atoms, and R ^{3 to} R ¹⁰ may be the same or different from each other. Good.

In formula (3), n represents an integer of 0 to 20.

In the general formulas (1), (2), and (3), n is preferably 1 or more. By setting n to 1 or more, the anti-coloring effect of the adhesive for optical members using the photocurable resin composition for optical members of the present invention can be further enhanced as compared with the case where n is 0. it can. In addition, when said n is 0, the photocurable resin composition for optical members of this invention is mix | blended in larger quantities than the said n when the aliphatic hydrocarbon compound which has a hydroxyl group mentioned later is 1 above. The transparency of the adhesive for optical members used can be made higher. If n exceeds 20, the viscosity may be too high, or the compatibility with other compounds may be deteriorated.

Moreover, among the compounds represented by the general formula (1), R ¹ and R ² are more preferably hydrogen, a methyl group, or an ethyl group. When R ¹ and R ² are hydrogen, a methyl group, or an ethyl group, the adhesive for optical members of the present invention has excellent light resistance and moisture resistance. Of these, R ¹ and R ² are particularly preferably methyl groups.

The upper limit of the viscosity of the photocationically polymerizable low-viscosity compound is 200 mPa · s. When the viscosity of the photocationically polymerizable low-viscosity compound exceeds 200 mPa · s, the viscosity of the resulting photocurable resin composition for optical members becomes too high, resulting in poor coatability. The preferable upper limit of the viscosity of the photocationically polymerizable low-viscosity compound is 50 mPa · s, and the more preferable upper limit is 20 mPa · s.

The photocurable resin composition for an optical member of the present invention contains a compound having at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton, and an oxetanyl group and / or an epoxy group.

Of the compounds having a fluorene skeleton and an oxetanyl group and / or an epoxy group, commercially available compounds include, for example, Ogsol PG, Ogsol PG100, Ogsol EG, Ogsol EG-210 (all manufactured by Osaka Gas Chemical Co., Ltd.) ) And the like.
Among the compounds having a naphthalene skeleton and an oxetanyl group and / or an epoxy group, examples of commercially available compounds include HP-4032 and HP-4032D (both manufactured by Dainippon Ink and Chemicals, Inc.). .
Among the compounds having a biphenyl skeleton and an oxetanyl group and / or an epoxy group, commercially available compounds include, for example, Epicoat YX4000, Epicoat YX4000H, Epicoat YL6121H, Epicoat YL6640, Epicoat YL6667 (all of which are Japan Epoxy Resins Co., Ltd.) Manufactured), OXBP (manufactured by Ube Industries), Denacol EX-142 (manufactured by Nagase ChemteX), and the like.
Among these, a compound having a fluorene skeleton and an oxetanyl group and / or an epoxy group is preferable, and a compound represented by the following general formula (4) is particularly preferable.

In Formula (4), R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ represent hydrogen or a linear or branched alkyl group having 1 to 12 carbon atoms.

100 in total of the content of the photocationically polymerizable low-viscosity compound and the content of the compound having at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and an oxetanyl group and / or an epoxy group. The preferred lower limit of the content of the compound having at least one structure selected from the above fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and the oxetanyl group and / or epoxy group is 1 part by weight, and the preferred upper limit. Is 50 parts by weight. When the content of the compound having at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and the compound having an oxetanyl group and / or an epoxy group is less than 1 part by weight, photocuring for an optical member is obtained. The refractive index of the cured product of the conductive resin composition may be low, or the transparency may be inferior. When the content of the compound having at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and the compound having an oxetanyl group and / or an epoxy group exceeds 50 parts by weight, the resulting photocurability for an optical member is obtained. The curability and adhesiveness of the resin composition may deteriorate, or the viscosity may become too high, resulting in poor coatability. The more preferable lower limit of the content of the compound having at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and the oxetanyl group and / or the epoxy group is 5 parts by weight, and the more preferable upper limit is 30 parts by weight. It is.

The photocurable resin composition for optical members of the present invention contains a cationic polymerization initiator.
The cationic polymerization initiator is not particularly limited as long as it generates a protonic acid or a Lewis acid by light irradiation, and may be an ionic photoacid generating type or a nonionic photoacid generating type. Also good.

The cationic polymerization initiator is not particularly limited, but an onium salt represented by the following general formula (5) is preferable. For an optical member obtained by using an onium salt represented by the following general formula (5) as the cationic polymerization initiator and a benzophenone derivative represented by the general formula (7) described later as a sensitizer. Coloring due to light or heat of the photocurable resin composition can be suppressed.

In formula (5), R ¹⁵ and R ¹⁶ are hydrogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, or Represents a C 1-20 carboxylic acid alkyl ester group. R ¹⁵ and R ¹⁶ may be the same as or different from each other.
In formula (5), X ⁻ represents PF ₆ ⁻ , AsF ₅ ⁻ , BF ₄ ⁻ , or a boronic acid represented by the following general formula (6).

Among them, the above cationic polymerization initiator has excellent transparency due to the use of the resulting photocurable resin composition for optical members, and is less susceptible to oxidation of the electrode at the interface with the electrode of the liquid crystal panel. Since it becomes what is excellent in a property, what consists of a salt which uses the bulky boronic acid represented by the said General formula (6) as a counter anion is suitable.

The content of the cationic polymerization initiator is not particularly limited, but the content of the photocationically polymerizable low-viscosity compound and at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and an oxetanyl group and The preferred lower limit is 0.1 parts by weight and the preferred upper limit is 10 parts by weight with respect to 100 parts by weight in total with the content of the compound having an epoxy group. If the content of the cationic polymerization initiator is less than 0.1 parts by weight, the cationic polymerization may not proceed sufficiently, or the curing reaction of the resulting photocurable resin composition for optical members may be too slow. There is. When the content of the cationic polymerization initiator exceeds 10 parts by weight, the curing reaction of the resulting photocurable resin composition for an optical member becomes too fast, resulting in a decrease in workability, or the resulting photocuring for optical member. The curable resin composition may become a non-uniform cured product. The minimum with more preferable content of the said cationic polymerization initiator is 0.3 weight part, and a more preferable upper limit is 5 weight part.

The photocurable resin composition for an optical member of the present invention preferably contains a sensitizer composed of a benzophenone derivative represented by the following general formula (7). The sensitizer has a role of further improving the polymerization initiation efficiency of the cationic polymerization initiator and further promoting the curing reaction of the photocurable resin composition for an optical member of the present invention.

In formula (7), R ¹⁷ and R ¹⁸ represent hydrogen, a substituent represented by the following general formula (8-1), or a substituent represented by the following general formula (8-2). R ¹⁷ and R ¹⁸ may be the same as or different from each other.

In formulas (8-1) and (8-2), R ¹⁹ is hydrogen, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxyl group having 1 to 20 carbon atoms, a halogen atom, or a hydroxyl group. Represents a carboxyl group or a carboxylic acid alkyl ester group having 1 to 20 carbon atoms.

Specific examples of the benzophenone derivative represented by the general formula (7) include benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4′-bis (dimethylamino) benzophenone, 4- Examples include benzoyl-4′methyldiphenyl sulfide.

Although the content of the sensitizer is not particularly limited, the content of the photocationically polymerizable low-viscosity compound, at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and an oxetanyl group and / or Alternatively, the preferred lower limit is 0.05 parts by weight and the preferred upper limit is 3 parts by weight with respect to 100 parts by weight in total with the content of the compound having an epoxy group. When the content of the sensitizer is less than 0.05 parts by weight, the sensitizing effect may not be sufficiently obtained. When the content of the sensitizer exceeds 3 parts by weight, absorption may be excessively increased and light may not be transmitted to the deep part. The minimum with more preferable content of the said sensitizer is 0.1 weight part, and a more preferable upper limit is 1 weight part.

The photocurable resin composition for an optical member of the present invention preferably further contains a curing retardant. By containing the curing retarder, the resulting adhesive using the photocurable resin composition for optical members has a longer pod life and improved coatability. Further, since the bonding and sealing can be performed after irradiating light once, it is possible to bond and seal a member that may be deteriorated by light such as an organic EL element.

The said hardening retarder is not specifically limited, For example, a polyether compound etc. are mentioned.
The polyether compound is not particularly limited, and examples thereof include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and a crown ether compound. Of these, crown ether compounds are preferred.

The crown ether compound is not particularly limited, and examples thereof include 12-crown-4, 15-crown-5, 18-crown-6, 24-crown-8, and a structure represented by the following general formula (9). And the like.

In formula (9), at least one of R ^{20 to} R ³¹ represents an alkyl group having 1 to 20 carbon atoms. The alkyl group is selected from the group consisting of a linear or branched alkoxyl group having 1 to 20 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, and a carboxylic acid alkyl ester group having 1 to 20 carbon atoms. One or more functional groups may be substituted, and adjacent R ⁿ and R ^{n + 1} (where n represents an even number of 20 to 30) jointly form a cyclic alkyl skeleton. May be.

Among the curing retardants having the structure represented by the general formula (9), those having at least one cyclohexyl group are preferable. By having the cyclohexyl group, the skeleton of the crown ether is stabilized and the delay effect is enhanced.
Specific examples of the curing retardant having the structure represented by the general formula (9) having the cyclohexyl group include compounds having a structure represented by the following chemical formula (10).

The compound having the structure represented by the chemical formula (10) has two cyclohexyl groups at positions symmetrical with respect to a line passing through the center of the 18-crown-6-ether molecule. It is considered that the delay effect is enhanced without causing distortion or the like in the skeleton of the 6-ether molecule.

The content of the curing retardant is not particularly limited, but the content of the photocationically polymerizable low-viscosity compound, the at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and the oxetanyl group and / or Alternatively, the preferred lower limit is 0.05 parts by weight and the preferred upper limit is 5.0 parts by weight with respect to 100 parts by weight in total with the content of the compound having an epoxy group. When the content of the curing retarder is less than 0.05 parts by weight, the retardation effect may not be sufficiently imparted to the photocurable resin composition for an optical member of the present invention. When the content of the curing retardant exceeds 5.0 parts by weight, the outgas generated when the photocurable resin composition for an optical member of the present invention is cured increases, and the outgas has a great influence. It may be difficult to use the photocurable resin composition for an optical member of the present invention for use. The minimum with more preferable content of the said retarder is 0.1 weight part, and a more preferable upper limit is 3 weight part.

It is preferable that the photocurable resin composition for an optical member of the present invention further contains an aliphatic hydrocarbon compound having a hydroxyl group.
When the aliphatic hydrocarbon compound having a hydroxyl group is contained, the photocurable resin composition for an optical member of the present invention exhibits very high transparency, and the cured product is exposed to ultraviolet rays or heat. Even very high transparency can be maintained.

In the present specification, the aliphatic hydrocarbon compound having a hydroxyl group means a compound comprising an aliphatic hydrocarbon skeleton having no unsaturated double bond and a hydroxyl group.
The aliphatic hydrocarbon skeleton is not particularly limited, but is preferably an aliphatic hydrocarbon skeleton having 2 to 50 carbon atoms. If the number of carbon atoms is less than 2, the hydrophilicity may be too strong, resulting in poor compatibility, and the resulting photocurable resin composition for optical members may be highly hygroscopic. When the said carbon number exceeds 50, solubility may worsen or the viscosity of the photocurable resin composition for optical members obtained may become high too much.

The aliphatic hydrocarbon compound having a hydroxyl group is not particularly limited, and examples thereof include alcohols such as (poly) ethylene glycol, (poly) propylene glycol, (poly) tetramethylene glycol, glycerin, hydroxyethyl (meth) acrylate, and glycidol. Etc. Of these, (poly) propylene glycol and (poly) tetramethylene glycol are preferred.
When the photocationically polymerizable low-viscosity compound is an aliphatic hydrocarbon compound having a hydroxyl group, the photocationically polymerizable low-viscosity compound may be used as the aliphatic hydrocarbon compound having a hydroxyl group. The photocationically polymerizable low-viscosity compound that is the aliphatic hydrocarbon compound having a hydroxyl group is not particularly limited, and examples thereof include 3-methyl-3-hydroxymethyl oxetane and 3-ethyl-3-hydroxymethyl oxetane. Of these, 3-ethyl-3-hydroxymethyloxetane is preferable.

The aliphatic hydrocarbon compound having a hydroxyl group has a preferred lower limit of pKa value of 15 and a preferred upper limit of 19. When the pKa value of the aliphatic hydrocarbon compound having a hydroxyl group is less than 15, the acidity is too strong and the storage stability may be deteriorated. When the pKa value of the aliphatic hydrocarbon compound having a hydroxyl group exceeds 19, the basicity becomes too strong and the acid generated is weakened, so that curing inhibition may occur.

The content of the aliphatic hydrocarbon compound having a hydroxyl group is not particularly limited, but the content of the photocationically polymerizable low-viscosity compound and the fluorene skeleton, naphthalene skeleton, and at least one structure selected from a biphenyl skeleton, In addition, the preferable lower limit is 5 parts by weight and the preferable upper limit is 50 parts by weight with respect to 100 parts by weight in total with the content of the compound having an oxetanyl group and / or an epoxy group. When the content of the aliphatic hydrocarbon compound having a hydroxyl group is less than 5 parts by weight, the resulting photocurable resin composition for an optical member maintains sufficient transparency when exposed to ultraviolet rays or heat. May not be possible. When the content of the aliphatic hydrocarbon compound having a hydroxyl group exceeds 50 parts by weight, the curing reaction is inhibited, or the water absorption rate of the cured product of the resulting photocurable resin composition for optical members is increased. There is. The minimum with more preferable content of the aliphatic hydrocarbon compound which has the said hydroxyl group is 10 weight part, and a more preferable upper limit is 40 weight part.

The photocurable resin composition for an optical member of the present invention preferably further contains a thermosetting agent.
By containing the said thermosetting agent, thermosetting property can be provided to the photocurable resin composition for optical members of this invention.

The thermosetting agent is not particularly limited, and examples thereof include hydrazide compounds, imidazole derivatives, acid anhydrides, dicyandiamides, guanidine derivatives, modified aliphatic polyamines, addition products of various amines and epoxy resins, and the like.
The hydrazide compound is not particularly limited, and examples thereof include 1,3-bis [hydrazinocarbonoethyl-5-isopropylhydantoin].
The imidazole derivative is not particularly limited. For example, 1-cyanoethyl-2-phenylimidazole, N- [2- (2-methyl-1-imidazolyl) ethyl] urea, 2,4-diamino-6- [2′- Methylimidazolyl- (1 ′)]-ethyl-s-triazine, N, N′-bis (2-methyl-1-imidazolylethyl) urea, N, N ′-(2-methyl-1-imidazolylethyl) -adipamide 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole and the like.
The acid anhydride is not particularly limited, and examples thereof include tetrahydrophthalic anhydride, ethylene glycol bis (anhydro trimellitate) and the like.
These thermosetting agents may be used alone or in combination of two or more.

The content of the thermosetting agent is not particularly limited, but the content of the photocationically polymerizable low-viscosity compound and at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and an oxetanyl group and / or Alternatively, the preferred lower limit is 0.5 parts by weight and the preferred upper limit is 30 parts by weight relative to 100 parts by weight in total with the content of the compound having an epoxy group. If the content of the thermosetting agent is less than 0.5 parts by weight, sufficient thermosetting property may not be imparted to the resulting photocurable resin composition for optical members. When the content of the thermosetting agent exceeds 30 parts by weight, the storage stability of the resulting photocurable resin composition for optical members becomes insufficient, or the resulting photocurable resin composition for optical members is cured. The moisture resistance of things may deteriorate. The minimum with more preferable content of the said thermosetting agent is 1 weight part, and a more preferable upper limit is 15 weight part.

The photocurable resin composition for an optical member of the present invention preferably further contains a silane coupling agent. The said silane coupling agent has a role which improves the adhesiveness of the adhesive agent using the photocurable resin composition for optical members of this invention, a liquid crystal panel, a board | substrate, etc.

Specific examples of the silane coupling agent include γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-isocyanatopropyltrimethoxysilane. It is done. These silane compounds may be used alone or in combination of two or more.

The content of the silane coupling agent is not particularly limited, but the content of the photocationically polymerizable low-viscosity compound and at least one structure selected from the fluorene skeleton, naphthalene skeleton, and biphenyl skeleton, and an oxetanyl group and The preferred lower limit is 0.1 parts by weight and the preferred upper limit is 10 parts by weight with respect to 100 parts by weight in total with the content of the compound having an epoxy group. When the content of the silane coupling agent is less than 0.1 parts by weight, the effect of improving the adhesiveness of the adhesive using the resulting photocurable resin composition for optical members is hardly obtained. is there. When content of the said silane coupling agent exceeds 10 weight part, an excess silane coupling agent may bleed out. The minimum with more preferable content of the said silane coupling agent is 0.5 weight part, and a more preferable upper limit is 5 weight part.

The photocurable resin composition for optical members of the present invention may contain a filler as long as the object of the present invention is not impaired.
The said filler is not specifically limited, For example, an inorganic filler, an organic filler, etc. are mentioned.
The inorganic filler is not particularly limited, for example, talc, asbestos, silica, smectite, bentonite, calcium carbonate, magnesium carbonate, alumina, montmorillonite, diatomaceous earth, magnesium oxide, titanium oxide, magnesium hydroxide, aluminum hydroxide, glass beads, Examples include barium sulfate, gypsum, calcium silicate, and sericite activated clay.
The organic filler is not particularly limited, and examples thereof include polyester fine particles, polyurethane fine particles, vinyl polymer fine particles, and acrylic polymer fine particles.

The method for producing the photocurable resin composition for an optical member of the present invention is not particularly limited. For example, using a mixer such as a homodisper, a homomixer, a universal mixer, a planetarium mixer, a kneader, or a three roll, A cationically polymerizable low-viscosity compound, at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton, a compound having an oxetanyl group and / or an epoxy group, a cationic polymerization initiator, and The method of mixing with additives, such as the thermosetting agent to add and a silane coupling agent, is mentioned.

The lower limit of the viscosity of the photocurable resin composition for an optical member of the present invention when measured using a cone rotor viscometer at 25 ° C. and 10 rpm is 5 mPa · s, and the upper limit is 500 mPa · s. When the viscosity of the photocurable resin composition for optical members is less than 5 mPa · s, for example, when the substrates are bonded using an adhesive using the obtained photocurable resin composition for optical members In addition, the coating layer cannot maintain its shape. When the viscosity of the photocurable resin composition for an optical member exceeds 500 mPa · s, it becomes difficult to apply uniformly. The minimum with a preferable viscosity of the said photocurable resin composition for optical members is 20 mPa * s, and a preferable upper limit is 300 mPa * s. The minimum with more preferable viscosity of the said photocurable resin composition for optical members is 25 mPa * s, and a more preferable upper limit is 200 mPa * s.

The lower limit of the refractive index of the cured product of the photocurable resin composition for an optical member of the present invention when the thickness is 50 μm is 1.50. When the refractive index is less than 1.50, when used between substrates of a touch panel, a difference in refractive index with a member such as ITO becomes large, and the obtained touch panel is inferior in optical characteristics. The preferable lower limit of the refractive index is 1.55, and the preferable upper limit is 1.7. A more preferable upper limit of the refractive index is 1.65.
The refractive index can be measured on a sample having a thickness of 50 μm at 25 ° C. using an Abbe refractometer and using sodium D-line as a light source.

The preferable lower limit of the light transmittance in the visible light region when the thickness of the cured product of the photocurable resin composition for an optical member of the present invention is 50 μm is 90%. When the light transmittance of the cured product is less than 90%, an adhesive using the photocurable resin composition for an optical member of the present invention may be inferior in optical properties.

The preferable lower limit of the hardness of the cured product of the photocurable resin composition for an optical member of the present invention, measured in accordance with JIS K6253 type E, is 10, and the preferable upper limit is 60. If the hardness of the cured product is less than 10, sufficient strength may not be obtained. When the hardness of the cured product exceeds 60, the difference in linear expansion coefficient between the adhesive and the member using the photocurable resin composition for an optical member of the present invention cannot be absorbed, and the member is deformed or peeled off due to stress. May occur. The more preferable lower limit of the hardness of the cured product is 20, and the more preferable upper limit is 50.

The photocurable resin composition for an optical member of the present invention is suitably used for applications such as a sealing agent for organic EL elements, an adhesive used for bonding a liquid crystal panel of a liquid crystal display device and a transparent member, and the like. be able to. The adhesive agent using the photocurable resin composition for optical members of the present invention is also one aspect of the present invention.

The adhesive of the present invention may be applied directly to a substrate, or may be transferred to a target substrate after being applied to another substrate. Although the thickness of the adhesion layer by the adhesive agent of this invention after coating is suitably determined by a material, a use, etc., generally it is about 1-200 micrometers.

The said base material is not specifically limited, For example, a plastic film, glass, a polarizing plate, a lens, a prism etc. are mentioned.

The method for applying the adhesive of the present invention is not particularly limited, and for example, it can be performed using a coating machine such as a roll coater or a die coater. In particular, in order to apply uniformly, it is preferable to apply to the substrate while heating with a die coater or the like.

The adhesive of this invention can be hardened by irradiating the light of the wavelength of 300 nm-400 nm and the integrated light quantity of 300-3000 mJ / cm < ² > after coating.
The adhesive of the present invention preferably has a pot life of 1 minute or more until the curing reaction proceeds after irradiation with light and adhesion cannot be performed. If the pot life is less than 1 minute, curing proceeds before the substrates are bonded together, and sufficient adhesive strength may not be obtained. The pot life can be appropriately adjusted by adjusting the amount of the above-mentioned aliphatic hydrocarbon having a hydroxyl group or the curing retarder.

The light source for irradiating the adhesive of the present invention with light is not particularly limited. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, an excimer laser, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, Examples thereof include metal halide lamps, sodium lamps, halogen lamps, xenon lamps, fluorescent lamps, sunlight, and electron beam irradiation devices. These light sources may be used independently and 2 or more types may be used together. These light sources are appropriately selected according to the absorption wavelength of the cationic polymerization initiator.

Examples of the irradiation procedure of the light source to the adhesive of the present invention include simultaneous irradiation of various light sources, sequential irradiation with a time difference, combined irradiation of simultaneous irradiation and sequential irradiation, and any irradiation means. It may be used.
In curing the adhesive of the present invention, heating may be performed simultaneously with light irradiation in order to further accelerate the photocationic polymerization of a photocationically polymerizable low-viscosity compound or the like and further shorten the curing time. Although the heating temperature in the case of performing the said heating is not specifically limited, It is preferable that it is about 50-100 degreeC.

A touch panel using the adhesive of the present invention is also one aspect of the present invention.

As a method for producing the touch panel of the present invention, for example, the adhesive of the present invention is applied to the entire surface or a part of one of the base materials, irradiated with light, and then the base of one of the substrates is interposed through the adhesive of the present invention. A method having a step of bonding the other substrate to the material and curing it at room temperature or under heating can be used.
Specifically, for example, for two ITO glasses, after applying the adhesive of the present invention to the bonding surface of one ITO glass and irradiating with ultraviolet rays, the other ITO glass is pasted and cured until normal or The method of fixing under heating is mentioned.
Such a touch panel manufacturing method is, for example, a case where an opaque electrode or a black matrix is formed on the surface of the base material, and it is difficult to irradiate light to the adhesive of the present invention through the base material. It can be used suitably. Furthermore, after bonding, the position can be adjusted before being cured, or it can be cured while being pressed, so that the dimensional accuracy can be improved.

As another method for producing the touch panel of the present invention, for example, after injecting the adhesive of the present invention between one base material and the other base material, the adhesive of the present invention is irradiated by light irradiation or the like. A curing method can be used.
When injecting the adhesive of the present invention, it can be filled without leakage by sealing a part of the periphery. Moreover, an adhesive can be inject | poured, without enclosing a bubble by providing an injection port and making the inside a vacuum (FIG. 1).

According to the present invention, there is provided a photocurable resin composition for an optical member that is excellent in coatability and transparency and that can provide an adhesive for an optical member that hardly causes optical distortion with a substrate or an optical member. Can be provided. Moreover, according to this invention, the touchscreen formed using the adhesive agent using this photocurable resin composition for optical members and this adhesive agent can be provided.

It is the schematic diagram which showed the method of vacuum-injecting the adhesive agent of this invention between base materials.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.

Example 1
Hydrogenated bisphenol F-type epoxy resin (Japan Epoxy Resin, “Epicoat YL6753”, viscosity 190 mPa · s) 40 parts by weight and di [1-ethyl (3-oxetanyl)] methyl ether (Toa Gosei Co., Ltd., “Aron 30 parts by weight of oxetane OXT-221, viscosity 13 mPa · s), 25 parts by weight of 3-ethyl-3-hydroxymethyloxetane (manufactured by Toagosei Co., Ltd., “Aron oxetane OXT-101”, viscosity 20 mPa · s), and fluorene 5 parts by weight of Ogsol EG (manufactured by Osaka Gas Chemical Co., Ltd.) as a compound having a skeleton and an epoxy group, and 1 part by weight of an iodonium borate cationic polymerization initiator (manufactured by Rhodia, “RP2074”) as a cationic polymerization initiator, 4-benzoyl-4′methyldiphenyl sulfide 0 as a sensitizer After mixing with 1 part by weight and heating to 80 ° C., the mixture was uniformly stirred and mixed at a stirring speed of 3000 rpm using a homodisper type stirring mixer (made by Tokushu Kika Kogyo Co., Ltd., “Homodisper L type”). A photocurable resin composition for members was prepared.

(Example 2)
The amount of di [1-ethyl (3-oxetanyl)] methyl ether was changed to 25 parts by weight, the amount of 3-ethyl-3-hydroxymethyloxetane was changed to 30 parts by weight, and no sensitizer was used. Except that, a photocurable resin composition for an optical member was produced in the same manner as in Example 1.

(Example 3)
Instead of 1 part by weight of RP2074 (manufactured by Rhodia) as a cationic polymerization initiator, 1 part by weight of CPI-210 (manufactured by San Apro) was used, and the same procedure as in Example 1 was performed except that no sensitizer was used. A photocurable resin composition for an optical member was produced.

Example 4
For optical members in the same manner as in Example 1 except that di [1-ethyl (3-oxetanyl)] methyl ether was not used and the blending amount of 3-ethyl-3-hydroxymethyloxetane was changed to 55 parts by weight. A photocurable resin composition was prepared.

(Example 5)
The amount of di [1-ethyl (3-oxetanyl)] methyl ether was changed to 20 parts by weight, the amount of 3-ethyl-3-hydroxymethyloxetane was changed to 20 parts by weight, and a fluorene skeleton and an epoxy group 5 parts by weight of Ogsol EG (Osaka Gas Chemical Co., Ltd.) instead of 5 parts by weight of Ogsol EG (Osaka Gas Chemical Co., Ltd.) as a compound having RP2074 (Rhodia Co., Ltd.) as a cationic polymerization initiator In addition, a photocurable resin composition for an optical member was produced in the same manner as in Example 1 except that 1 part by weight of CPI-210 (manufactured by San Apro) was used.

(Comparative Example 1)
A photocurable resin composition for an optical member was produced in the same manner as in Example 1 except that a compound having a fluorene skeleton and an epoxy group was not used.

(Comparative Example 2)
The amount of Epicoat YL6753 was changed to 20 parts by weight, the amount of 3-ethyl-3-hydroxymethyloxetane was changed to 20 parts by weight, and the amount of Oxol EG (Osaka Gas Chemical Co., Ltd.) was changed to 30 parts by weight. A photocurable resin composition for an optical member was produced in the same manner as in Example 1 except that the change was made.

(Comparative Example 3)
Instead of 40 parts by weight of Epicoat YL6753, 95 parts by weight of Epicoat YX8000 (manufactured by Japan Epoxy Resin Co., Ltd., viscosity 18500 mPa · s) which is a hydrogenated bisphenol A type epoxy resin was used, and di [1-ethyl (3-oxetanyl)] A photocurable resin composition for an optical member was produced in the same manner as in Example 1 except that methyl ether and 3-ethyl-3-hydroxymethyloxetane were not used.

(Evaluation)
The following evaluation was performed about the photocurable resin composition for optical members obtained by the Example and the comparative example. The results are shown in Table 1.

(1) Measurement of viscosity The viscosity of the photocurable resin composition for optical members obtained under the conditions of 25 ° C and 10 rpm was measured using a cone rotor viscometer.

(2) Measurement of refractive index The photocurable resin composition for an optical member obtained in Examples and Comparative Examples was applied on a PET film and bonded with another PET film, and ultraviolet rays of 1500 mJ / cm ² were applied. After the irradiation, the photocurable resin composition for optical members was cured by holding at 80 ° C. for 10 minutes. The thickness of the cured resin was approximately 50 μm.
The refractive index was measured using an Abbe refractometer (manufactured by Atago Co., Ltd., “DR-M2”) at 25 ° C. using sodium D-line as a light source.

(3) An initial light transmittance of 0.7 mm between ITO glasses is maintained at 50 μm, and the photocurable resin compositions for optical members obtained in Examples and Comparative Examples are injected between these glasses to obtain 1500 mJ. After irradiating UV light of / cm ^2, the photocurable resin composition for optical members was cured by holding at 80 ° C. for 10 minutes, and samples according to Examples and Comparative Examples were respectively produced.
Using the obtained sample, the absorbance at wavelengths of 400 nm, 550 nm and 780 nm was measured using a spectrophotometer (manufactured by Hitachi, Ltd., U-3000, conditions 300 to 800 nm), and the initial light transmittance was calculated. .

(4) Samples according to Examples and Comparative Examples produced in the same manner as the light transmittance after heating (3) were 1000 in an oven set to 85 ° C. (Espec Corp., “Perfect Oven PH-201”). Heated for hours. Thereafter, the absorbance of each sample at wavelengths of 400 nm, 550 nm, and 780 nm was measured using a spectrophotometer (manufactured by Hitachi, Ltd., “U-3000”), and the light transmittance after the heat resistance test was calculated.

(5) Samples according to Examples and Comparative Examples prepared in the same manner as (3) using a light transmittance weatherometer after UV irradiation ("Super Xenon Weather Meter SX75" manufactured by Suga Test Instruments Co., Ltd.) The light resistance test was performed for 1000 hours. Thereafter, the absorbance of each sample at wavelengths of 400 nm, 550 nm, and 780 nm was measured using a spectrophotometer (manufactured by Hitachi, Ltd., “U-3000”), and the light transmittance after the light resistance test was measured. Calculated.

(6) Transparency As shown in FIG. 1, two ITO glasses were bonded as a base material, and then the photocurable resin compositions for optical members obtained in Examples and Comparative Examples were vacuum-injected as an adhesive. When it was visually confirmed, it was evaluated as “◯”, and when it was not transparent due to white turbidity, it was evaluated as “x”.

(7) Vacuum injection property As shown in FIG. 1, two ITO glasses were laminated as a base material, and then the photocurable resin compositions for optical members obtained in Examples and Comparative Examples were vacuum-injected as adhesives. . The degree of vacuum between the laminated ITO glasses is 3 × 10 ⁻² mmHg, and the injection is finished to the upper part within 10 minutes after dipping into the photocurable resin composition for optical members obtained in Examples and Comparative Examples Was evaluated as “X” when the injection was over to the upper part but exceeded 10 minutes.

According to the present invention, there is provided a photocurable resin composition for an optical member that is excellent in coatability and transparency and that can provide an adhesive for an optical member that hardly causes optical distortion with a substrate or an optical member. Can be provided. Moreover, according to this invention, the touchscreen formed using the adhesive agent using this photocurable resin composition for optical members and this adhesive agent can be provided.

1 Base material 2 Adhesive

Claims (5)

A compound having at least one photocationically polymerizable functional group in the molecule and having a viscosity of 200 mPa · s or less when measured at 25 ° C. and 10 rpm using a cone rotor viscometer;
A compound having at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton, and an oxetanyl group and / or an epoxy group;
A cationic polymerization initiator,
The viscosity when measured at 25 ° C. and 10 rpm using a cone rotor viscometer is 5 to 500 mPa · s, and the refractive index of the cured product when the thickness is 50 μm is 1.50 or more. A photocurable resin composition for an optical member. The compound having at least one structure selected from a fluorene skeleton, a naphthalene skeleton, and a biphenyl skeleton, and an oxetanyl group and / or an epoxy group is a compound represented by the following general formula (4): Item 2. A photocurable resin composition for an optical member according to Item 1.

In Formula (4), R ¹¹ , R ¹² , R ¹³ , and R ¹⁴ represent hydrogen or a linear or branched alkyl group having 1 to 12 carbon atoms. Content of a compound having at least one photocationically polymerizable functional group in the molecule and having a viscosity of 200 mPa · s or less when measured at 25 ° C. and 10 rpm using a cone rotor viscometer Fluorene skeleton, naphthalene skeleton, and at least one structure selected from a naphthylene skeleton and a biphenyl skeleton, and a total of 100 parts by weight of a compound having an oxetanyl group and / or an epoxy group, a fluorene skeleton, a naphthalene skeleton 3. The optical member according to claim 1, wherein the content of the compound having at least one structure selected from a biphenyl skeleton and a compound having an oxetanyl group and / or an epoxy group is 1 to 50 parts by weight. Photocurable resin composition. An adhesive comprising the photocurable resin composition for an optical member according to claim 1, 2 or 3. A touch panel comprising the adhesive according to claim 4.

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