JP2005314687A - Photo-curable resin composition, cationic photopolymerization initiator, adhesive for display element and display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo-curable resin composition which has low curing contraction coefficient, good transparency, high heat resistance, low viscosity and good handleability, to provide a cationic photopolymerization initiator used for the photo-curable resin composition, to provide an adhesive which comprises the photo-curable resin composition and is used for display elements, and to provide a display element using the adhesive. <P>SOLUTION: This photo-curable resin composition is characterized by comprising 100 pts.wt. of a cationically photopolymerizable compound having at least one functional group selected from the group consisting of epoxy group, oxetanyl group and vinyl ether group, 20 to 80 pts.wt. of an ortho spiro ester compound and/or a cyclic carbonate compound, and 0.05 to 20 pts.wt. of a photo cation polymerization initiator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention is a photocurable resin composition having a low cure shrinkage, good transparency, high heat resistance, low viscosity and good handleability, and photocationic polymerization used for the photocurable resin composition The present invention relates to an initiator, an adhesive for display elements containing the photocurable resin composition, and a display element using the adhesive.

Display elements such as electroluminescence elements (hereinafter also referred to as EL elements) and liquid crystal display elements are attracting attention as flat panel displays. In recent years, these flat panel displays have been increasingly increased in size.

In the case of an organic EL element, in order to obtain a practical organic EL element, it is necessary to increase the lifetime by sealing the element. As a method for sealing an element, a method is generally used in which an element is sandwiched between sealing glasses via an adhesive, and then the adhesive is cured by heat or light to perform sealing. In particular, for large organic EL elements, a method for preventing bubbles from remaining between the adhesive and the sealing glass has also been proposed (for example, Patent Document 1).

However, when an organic EL element is manufactured by such a method, if shrinkage occurs when the adhesive is cured, voids, cracks, etc. may occur, or the adhesive strength may be reduced. There was a problem that sealing might be incomplete. In particular, in a large organic EL element, the problem of curing shrinkage becomes more prominent because the adhesive application surface is larger. Therefore, an adhesive for sealing an organic EL element having a low curing shrinkage rate has been demanded.

As a resin composition that can be used as an adhesive having a small curing shrinkage, for example, Patent Document 2 describes a resin composition containing an orthospiroester compound, and Patent Document 3 describes a cyclic carbonate compound. Patent Document 4 discloses a trifunctional or tetrafunctional liquid epoxy resin, a bifunctional glycidyl ether type epoxy resin, a rubber component, a liquid curing agent, and a resin containing metal powder. A composition is described. However, when an adhesive composed of these resin compositions is used for sealing an organic EL element, the resin composition of Patent Document 2 has a problem that the viscosity is too high and the step of bonding the sealing glass is difficult. In the resin composition of Patent Document 3, it is difficult to use in applications where the glass transition temperature is low and heat resistance is required, and in the resin composition of Patent Document 4, the transparency is low. was there.
JP 2002-216958 A JP-A-8-27267 JP-A-9-194565 Japanese Patent Laid-Open No. 10-292029

In view of the above situation, the present invention provides a photocurable resin composition having a low curing shrinkage ratio, good transparency, high heat resistance, low viscosity and good handleability, and the photocurable resin composition. An object of the present invention is to provide a photocationic polymerization initiator used in the above, an adhesive for display elements containing the photocurable resin composition, and a display element using the adhesive.

The present invention relates to 100 parts by weight of a photocationically polymerizable compound having at least one functional group selected from the group consisting of an epoxy group, an oxetanyl group and a vinyl ether group, an orthospiroester compound and / or a cyclic carbonate compound of 20 to 80 parts by weight. Part, and a photocurable resin composition containing 0.05 to 20 parts by weight of a cationic photopolymerization initiator.
The present invention is described in detail below.

The photocurable resin composition of the present invention contains a photocationically polymerizable compound having at least one functional group selected from the group consisting of an epoxy group, an oxetanyl group and a vinyl ether group. Among them, an epoxy group or an oxetanyl group is preferable because photocuring property is high and photocuring efficiently proceeds even with a small amount of light. The cationic photopolymerizable compound may have at least one functional group in the molecule. The said cationic photopolymerizable compound may be used independently and 2 or more types may be used together.

The photocationically polymerizable compound having an epoxy group is not particularly limited, and examples thereof include bisphenol type epoxy resins such as bisphenol A type epoxy resins and bisphenol F type epoxy resins; phenol novolac type epoxy resins; cresol novolac type epoxy resins and the like. Novolak type 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; Resin; Alcohol type epoxy resin such as hydrogenated bisphenol A type epoxy resin; Halogenated epoxy resin such as brominated epoxy resin; Rubber modified epoxy resin; Urethane modified epoxy resin; Epoxidized polybutadiene Epoxidized styrene - butadiene - styrene block copolymer, epoxy group-containing polyester resin, epoxy group-containing polyurethane resins, epoxy group-containing acrylic resins. These photocationic polymerizable compounds having an epoxy group may be used alone or in combination of two or more.

Commercially available products of the above-mentioned photocationic polymerizable compound having an epoxy group are not particularly limited. For example, trade names “Epicoat 806”, “Epicoat 828”, “Epicoat 1001”, “Epicoat 1002” and the like manufactured by Japan Epoxy Resin Co., Ltd. And “Celoxide” series such as “Celoxide 2021” manufactured by Daicel Chemical Industries, Ltd., and the like.

The photocationically polymerizable compound having an oxetanyl group is not particularly limited, and examples thereof include phenoxymethyl oxetane, 3,3-bis (methoxymethyl) oxetane, 3,3-bis (phenoxymethyl) oxetane, and 3-ethyl-3. -(Phenoxymethyl) oxetane, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, 3-ethyl-3-{[3- (triethoxysilyl) propoxy] methyl} oxetane, di [1-ethyl ( 3-oxetanyl)] methyl ether, oxetanylsilsesquioxane, phenol novolac oxetane, 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene, biphenyloxetane and the like. These photocationically polymerizable compounds having an oxetanyl group may be used alone or in combination of two or more.

The cationic photopolymerizable compound having a vinyl ether group is not particularly limited. For example, n-propyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, cyclohexyl vinyl ether, 2-ethylhexyl vinyl ether, Dodecyl vinyl ether, octadecyl vinyl ether, 2-chloroethyl vinyl ether, ethylene glycol butyl vinyl ether, triethylene glycol methyl vinyl ether, benzoic acid (4-vinyloxy) butyl, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol Divinyl ether, butane-1,4-di -Divinyl ether, hexane-1,6-diol-divinyl ether, cyclohexane-1,4-dimethanol-divinyl ether, di (4-vinyloxy) butyl isophthalate, di (4-vinyloxy) butyl glutarate, succinic acid Acid di (4-vinyloxy) butyltrimethylolpropane trivinyl ether, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, 6-hydroxyhexyl vinyl ether, cyclohexane-1,4-dimethanol-monovinyl ether, diethylene glycol monovinyl ether, 3- Examples include aminopropyl vinyl ether, 2- (N, N-diethylamino) ethyl vinyl ether, urethane vinyl ether, and polyester vinyl ether. These photocationically polymerizable compounds having a vinyl ether group may be used alone or in combination of two or more.

The molecular weight of the photocationically polymerizable compound is not particularly limited, and may be any of a monomer, an oligomer, and a polymer, for example.

The photocurable resin composition of the present invention contains an orthospiroester compound and / or a cyclic carbonate compound. Since the above-mentioned orthospiroester compound and cyclic carbonate compound have a large volume expansion at the time of curing, the volume shrinkage at the time of curing as a whole is adjusted by blending it with the photocurable resin composition, and the low curing shrinkage rate The photocurable resin composition can be realized.

The ortho spiro ester compound is not particularly limited, and examples thereof include bisphenol A ortho spiro ester (γ-butyrolactone adduct) and ortho spiro ester compound represented by the following general formula (5).

式（５）中、ｍは、０〜１０の整数を表し、ｑは、２〜１０の整数を表し、Ａは、下記一般式（６）で表されるものである。

式（６）中、Ｒ^１５、Ｒ^１６は水素又は低級アルキル基を表す。

In formula (5), m represents an integer of 0 to 10, q represents an integer of 2 to 10, and A is represented by the following general formula (6).

In the formula (6), R ¹⁵ and R ¹⁶ represent hydrogen or a lower alkyl group.

式（７）中、Ａ及びｍは式（５）におけるものと同じものを表す。 Although it does not specifically limit as a method to manufacture the ortho spiro ester compound represented by the said General formula (5), For example, the diglycidyl ether and lactone represented by following General formula (7) are boron trifluoride. And a method of production by an addition reaction under a Friedel-Crafts type catalyst such as boron trifluoride-diethyl ether complex or an acidic catalyst.

In formula (7), A and m represent the same as in formula (5).

It does not specifically limit as said cyclic carbonate compound, For example, what is represented by following General formula (8), what is represented by following General formula (9), etc. are mentioned.

式（８）中、ｘ、ｙは、０〜３の整数を表し、Ｒ^１７、Ｒ^１８は、炭素数が１５以下であるアルキル基；フェニル、ナフチル等の芳香族基；アリル基を表す。

In formula (8), x and y represent an integer of 0 to 3, and R ¹⁷ and R ¹⁸ represent an alkyl group having 15 or less carbon atoms; an aromatic group such as phenyl or naphthyl; and an allyl group.

式（９）中、ｘ、ｙは、０〜３の整数を示し、Ｒ^１９、Ｒ^２０は、環状化合物を表す。

In formula (9), x and y represent an integer of 0 to 3, and R ¹⁹ and R ²⁰ represent a cyclic compound.

In the photocurable resin composition of the present invention, the lower limit of the content of the orthospiroester compound and / or the cyclic carbonate compound with respect to 100 parts by weight of the photocationically polymerizable compound is 20 parts by weight, and the upper limit is 80 parts by weight. If it is less than 20 parts by weight, the effect of reducing the curing shrinkage cannot be obtained, and if it exceeds 80 parts by weight, physical properties such as heat resistance are lowered. A preferred lower limit is 25 parts by weight and a preferred upper limit is 50 parts by weight.

The photocurable resin composition of the present invention contains a photocationic polymerization initiator.
The photocationic polymerization initiator may be an ionic photoacid generation type or a nonionic photoacid generation type.

The ionic photoacid generation type photocationic polymerization initiator is not particularly limited, for example,
Examples thereof include onium salts such as aromatic diazonium salts, aromatic halonium salts, and aromatic sulfonium salts, and organometallic complexes such as iron-allene complexes, titanocene complexes, and arylsilanol-aluminum complexes. These ionic photoacid-generating photocationic polymerization initiators may be used alone or in combination of two or more.
Among the ionic photoacid-generating photocationic polymerization initiators, those commercially available include, for example, “Adekaoptomer SP150”, “Adekaoptomer SP170” (above, manufactured by Asahi Denka Kogyo Co., Ltd.), “ UVE-1014 "(manufactured by General Electronics)," CD-1012 "(manufactured by Sartomer), and the like.

The non-ionic photoacid generation type photocationic polymerization initiator is not particularly limited. For example, nitrobenzyl ester, sulfonic acid derivative, phosphoric acid ester, phenolsulfonic acid ester, diazonaphthoquinone, N-hydroxyimidosulfonate, etc. Is mentioned.

As said photocationic polymerization initiator, the following general formula (1), the following general formula (2), the cation part represented by the following general formula (3), the anion part represented by the following general formula (4), Those consisting of are particularly preferred.
Such a photocationic polymerization initiator is also one aspect of the present invention.

式（１）、（２）、（３）中、Ｒ^１ 〜Ｒ^６は、それぞれ１価又は２価のフェニル基又は
ナフチル基を表し、前記フェニル基又はナフチル基は、直鎖状又は分枝鎖状Ｃ_１〜Ｃ_１２アルキル基、直鎖状又は分枝鎖状Ｃ_１ 〜Ｃ_１２アルコキシル基、ハロゲン原子、−ＯＨ
基、−ＣＯＯＨ基、及び、−ＣＯＯ−アルキルエステル基（ここで、アルキル部分は直鎖状又は分枝鎖状Ｃ_１〜Ｃ_１２残基である）からなる群より選択される少なくとも１種の基で置換されていてもよい。Ｒ^１〜Ｒ^６は、互いに同一であってもよいし異なっていてもよい。

In formulas (1), (2), and (3), R ^{1 to} R ⁶ each represent a monovalent or divalent phenyl group or naphthyl group, and the phenyl group or naphthyl group is linear or branched. Chain C ₁ -C ₁₂ alkyl group, linear or branched C ₁ -C ₁₂ alkoxyl group, halogen atom, —OH
At least one selected from the group consisting of a group, a —COOH group, and a —COO-alkyl ester group, wherein the alkyl moiety is a linear or branched C ₁ -C ₁₂ residue It may be substituted with a group. R ^{1 to} R ⁶ may be the same as or different from each other.

式（４）中、Ｂは、３価の硼素を表し、Ｒ^７〜Ｒ^１０の少なくとも１個は、炭素数６〜３０のハロゲン置換芳香族基を表す。

In formula (4), B represents trivalent boron, and at least one of R ^{7 to} R ¹⁰ represents a halogen-substituted aromatic group having 6 to 30 carbon atoms.

By using the one whose central anion is boron, the acid strength of the photocationic polymerization initiator is increased, so the curability of the photocurable resin composition using the photocationic polymerization initiator is improved, and the glass transition is high. A cured product having a temperature can be obtained. If such a photocurable resin composition is used as an adhesive for sealing, the cured product, that is, the moisture permeability (moisture permeability) of the sealed portion is lowered, so that the life of the obtained organic EL element is lengthened. Can improve reliability.

In the general formula (4), at least one of R ^{1 to} R ⁴ is a halogen-substituted aromatic group having 6 to 30 carbon atoms. The aromatic group is not particularly limited, and examples thereof include a phenyl group, a naphthyl group, and an anthracenyl group. Moreover, it does not specifically limit as a halogen substituent, For example, chlorine, a fluorine, etc. are mentioned, Especially, a fluorine is used suitably. The halogen substituent may be a halogen group directly bonded to the aromatic ring of the aromatic group, or it is introduced as a part of another substituent as in the case of a halo-hydrocarbyl substituent. There may be a fluoro-hydrocarbyl substituent among them.

Is not particularly restricted but useful boron-centered anions in the photo cationic polymerization initiator, for _{example, [3,5- (CF 3) 2} C 6 H 3] 4 B -, (C 6 F 5) 4 B -, _{(C 6 H 4 -p-CF} 3) 4 B -, (C 6 H 4 -m-CF 3) 4 B -, (C 6 H 4 -p-F) 4 B -, (C 6 F 5) ^{_{3 (CH 3) B -,}} (C 6 F 5) 3 (n-C 4 H 9) B -, (C 6 H 4 -p-CH 3) 3 (C 6 F 5) B -, (C 6 ^{_{F 5) 3 FB -, (}} C 6 H 5) 3 (C 6 F 5) B -, (CH 3) 2 (C 6 H 4 -p-CF 3) 2 B -, (C 6 F 5) 3 _{(n-C 18 H 37 O} ) B - , and the like. Especially, what is represented by a following formula (4-1) is suitable.

When an organic EL device is sealed using an ionic photoacid-generating photocationic polymerization initiator, electrode oxidation occurs at the interface between the electrode of the device and the adhesive, resulting in durability of the organic EL device. Sexuality may be impaired. When the thing which has an anion part represented by the said Formula (4-1) is used as said photocationic polymerization initiator, such oxidation of an electrode can be suppressed effectively. As a commercial item of the photocationic polymerization initiator which has an anion part represented by the said Formula (4-1), "Photoinitiator 2074" (made by Rhodia) etc. are mentioned, for example.

Examples of the cation moiety represented by the general formula (2) include those represented by the following general formula (2-1), and examples of the cation moiety represented by the general formula (3) include the following general formula (3). Those represented by -1) are preferred. The photocationic polymerization initiator having such an anion moiety absorbs light having a wavelength of 300 nm or more, preferably light having a wavelength of 300 to 400 nm, and is colored when blended in the photocurable resin composition. It is excellent in the prevention effect and the glass transition temperature increase effect of the cured product.

式（２−１）、（３−１）中、Ｒ^１１〜Ｒ^１４は、水素原子、直鎖状又は分枝鎖状Ｃ_１〜Ｃ_１２アルキル基、直鎖状又は分枝鎖状Ｃ_１ 〜Ｃ_１２アルコキシル基、ハロゲン原子、
−ＯＨ基、−ＣＯＯＨ基、及び、−ＣＯＯ−アルキルエステル基（ここで、アルキル部分は直鎖状又は分枝鎖状Ｃ_１〜Ｃ_１２残基である）からなる群より選択される少なくとも１種の基を表す。Ｒ^１１〜Ｒ^１４は、互いに同一であってもよいし異なっていてもよい。

In formulas (2-1) and (3-1), R ^{11 to} R ¹⁴ are hydrogen atoms, linear or branched C _{1 to} C ₁₂ alkyl groups, linear or branched C _1. -C ₁₂ alkoxyl group, a halogen atom,
At least one selected from the group consisting of —OH group, —COOH group, and —COO-alkyl ester group (wherein the alkyl moiety is a linear or branched C _{1 to} C ₁₂ residue). Represents a group of species. R ^{11 to} R ¹⁴ may be the same as or different from each other.

In the photocurable resin composition of the present invention, the lower limit of the content of the photocationic polymerization initiator with respect to 100 parts by weight of the photocationic polymerizable compound is 0.05 parts by weight, and the upper limit is 20 parts by weight. If it is less than 0.05 parts by weight, the photocationic polymerization does not proceed sufficiently or the reaction becomes too slow, and if it exceeds 20 parts by weight, the reaction becomes too fast and the workability decreases, May become uneven. A preferred lower limit is 0.1 parts by weight and a preferred upper limit is 5 parts by weight.

The photocurable resin composition of the present invention preferably further contains a curing controller in order to control the pot life and curing time after light irradiation.
The curing controller is not particularly limited, and examples thereof include an aliphatic hydrocarbon having a hydroxyl group and a compound having an ether bond. These curing control agents may be used alone or in combination of two or more.

The aliphatic hydrocarbon having a hydroxyl group is not particularly limited, and examples thereof include polyfunctional hydroxyl group-containing compounds such as glycerin and pentaerythritol.
The compound having an ether bond is not particularly limited, and examples thereof include polyalkylene oxides such as polyethylene glycol, polypropylene glycol, and polyoxytetramethylene glycol, and crown ethers.

When polyalkylene oxide is used as the curing controller, the terminal may be a hydroxyl group, may be etherified or esterified with another compound, or may be a functional group such as an epoxy group. . Of these, polyalkylene oxide having a terminal hydroxyl group or epoxy group is preferable because it reacts with the above-mentioned photocationically polymerizable compound.
As the polyalkylene oxide, a polyalkylene oxide-added bisphenol derivative is also preferably used, and particularly a compound having a terminal hydroxyl group or epoxy group is more preferably used. Of these, commercially available products are not particularly limited. For example, “Likaresin BEO-60E”, “Likaresin BPO-20E”, “Likaresin EO-20”, “Likaresin PO-20” (all manufactured by Shin Nippon Rika Co., Ltd.) ) And the like.

Examples of the crown ether include 12-crown-4, 15-crown-5, and 18-crown-6.

In the photocurable resin composition of the present invention, the preferred lower limit of the content of the curing control agent with respect to 100 parts by weight of the photocationically polymerizable compound is 0.1 parts by weight, and the upper limit is 50 parts by weight. If the amount is less than 0.1 parts by weight, a sufficient pot life may not be obtained after light irradiation. If the amount exceeds 50 parts by weight, photocationic polymerization may not proceed sufficiently, or the reaction may become too slow. There are things to do. A more preferred lower limit is 0.5 parts by weight, a preferred upper limit is 20 parts by weight, and a more preferred upper limit is 10 parts by weight.

The photocurable resin composition of the present invention may contain various conventionally known additives such as a photosensitizer, an inorganic filler, an adhesion improver, a reinforcing agent, a softener, a plasticizer, and a viscosity modifier. Good.
However, the additive preferably has a difference in average refractive index measured at 25 ° C. from the photocationic polymerizable compound of 0.05 or less. If it exceeds 0.05, the transparency of the cured product may be insufficient.

The photosensitizer further improves the efficiency of the photocationic polymerization initiator and further promotes the photocationic polymerization of the photocationically polymerizable compound.
The photosensitizer is not particularly limited, and examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreductive dyes. Specific examples include, for example, benzoin derivatives such as benzoin methyl ether and benzoin isopropyl ether; benzophenones such as benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, and 4,4′-bis (dimethylamino) benzophenone. Derivatives; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone. These photosensitizers may be used independently and 2 or more types may be used together.

The said inorganic filler improves the mechanical physical property of the hardened | cured material of a photocurable resin composition. The inorganic filler is not particularly limited, and examples thereof include carbonates or bicarbonates of alkali metals or alkaline earth metals such as calcium carbonate, calcium bicarbonate, sodium carbonate, and sodium bicarbonate described above; colloidal silica, talc, Examples include inorganic powders such as clay, mica (mica), and titanium oxide; inorganic hollow bodies such as glass balloons, alumina balloons, and ceramic balloons; inorganic fiber bodies such as glass fibers. These inorganic fillers may be used alone or in combination of two or more.
The inorganic filler preferably has an average particle size of 0.5 μm or less. If it exceeds 0.5 μm, the transparency of the cured product of the photocurable resin composition may be insufficient.

The photocurable resin composition of the present invention contains a compound that reacts with an acid generated in the composition or an ion exchange resin in order to improve the durability of the element electrode within a range that does not impair the transparency of the cured product. May be.
Examples of the compound that reacts with the generated acid include substances that neutralize the acid, such as carbonates or bicarbonates of alkali metals or alkaline earth metals. Specifically, calcium carbonate, calcium hydrogen carbonate, sodium carbonate, sodium hydrogen carbonate or the like is used.
As the ion exchange resin, any of a cation exchange type, an anion exchange type, and a both ion exchange type can be used, and in particular, a cation exchange type or a both ion exchange type capable of adsorbing chloride ions. Is preferred.

In order to improve moisture permeability, adhesive strength, cure shrinkage, thermal expansion coefficient, etc., as long as the photocurable resin composition of the present invention does not impair the transparency of the cured product, nylon beads, acrylic beads, silicon beads, Organic spherical bodies such as fluororesin beads; organic hollow bodies such as vinylidene chloride balloons and acrylic balloons; single fibers such as polyester, rayon, nylon, and cellulose may be contained.

The photo-curable resin composition of the present invention contains a water-absorbing material and the like in order to prevent moisture from entering the cell when used as an adhesive for a display element within a range that does not impair the transparency of the cured product. May be. The water-absorbing material is not particularly limited, and examples thereof include oxides of alkaline earth metals such as silica gel, molecular sieve, calcium oxide, barium oxide, and strontium oxide.

The photocurable resin composition of the present invention preferably has a cure shrinkage of 4% or less. When the curing shrinkage rate exceeds 4%, for example, when used for sealing an EL element, there may be a problem that the element is not completely sealed due to generation of voids, cracks or the like or a decrease in adhesive strength.
In addition, the said cure shrinkage rate can be calculated | required as a volume shrinkage rate (%) from the specific gravity difference before and behind hardening. In this case, the specific gravity is measured at a measurement temperature of 25 ° C.

In the photocurable resin composition of the present invention, the cured product preferably has a transmittance of 80% or more at a wavelength of 380 to 780 nm measured using a spectrophotometer. When it is less than 80%, when the EL device is sealed using the photocurable resin composition of the present invention, the optical properties such as transparency of the obtained EL device may be insufficient.
In the present specification, the transmittance of the cured product of the photocurable resin composition is a cured coating film measured using a spectrophotometer (for example, trade name “COLOR ANALYZER TC-1800M”, manufactured by Tokyo Denshoku Co., Ltd.). Means the transmittance (%). Moreover, the transmittance | permeability in wavelength 380-780 nm being 80% or more means that the transmittance | permeability is 80% or more in any wavelength in wavelength 380-780 nm.

The cured product of the photocurable resin composition of the present invention preferably has a glass transition temperature of 80 ° C. or higher. When the temperature is less than 80 ° C., the moisture permeability of the cured product increases, and it becomes difficult to achieve a long lifetime of the resulting EL element when the EL element is sealed.
The glass transition temperature was determined by measuring the dynamic viscoelasticity at a heating rate of 10 ° C./min for a measurement coating film prepared in the same manner as in the transmittance measurement. It is possible to perform measurement by determining the peak value of tan δ.

The photocurable resin composition of the present invention preferably has a pot life of 1 minute or longer after irradiation with light until the curing reaction proceeds and adhesion cannot be performed. If it is less than 1 minute, curing proceeds before the substrates are bonded together, and sufficient adhesive strength may not be obtained.

The method for producing the photocurable resin composition of the present invention is not particularly limited. For example, the photocationically polymerizable compound, the orthospiroester compound and / or the cyclic carbonate compound, the photocationic polymerization initiator, and as necessary. Examples include a method of mixing each predetermined amount of various additives to be added according to a homodisper, a homomixer, a universal mixer, a planetarium mixer, a kneader, a triple roll, etc. at room temperature or under heating. It is done. In addition, it is preferable that manufacture of the photocurable resin composition of this invention is performed in the state which interrupted | blocked light.

Since the photocurable resin composition of the present invention has the above-described configuration, it has a low cure shrinkage, good transparency, high heat resistance, low viscosity, and good handleability. In particular, when a curing control agent is contained, the reaction proceeds after light irradiation and after light is blocked, and curing is completed. For this reason, for example, when sealing an element with the adhesive for display elements containing the photocurable resin composition of the present invention, the adhesive is applied to the back plate, and the adhesive is irradiated with light to activate. After being made light, the light can be blocked, the back plate and the substrate on which the element is formed can be attached to seal the element, and the element can be sealed without being exposed to light or heat. .

It does not specifically limit as a use of the photocurable resin composition of this invention, For example, it can use for various uses, such as an adhesive agent, a sealing agent, a single-sided tape, a double-sided tape, a sealing film. In addition, it can be suitably used for a transparent or translucent structure such as a display element through these adhesive, sealant, single-sided tape, double-sided tape, sealing film and the like. In particular, it is particularly suitable as an adhesive for display elements when producing display elements such as EL elements and liquid crystal display elements.
The adhesive for display elements containing the photocurable resin composition of the present invention is also one aspect of the present invention.

A display element using the adhesive for a display element of the present invention is also one aspect of the present invention.
Although it does not specifically limit as a display element of this invention, For example, an EL element, a liquid crystal display element, etc. are mentioned. As said EL element, an organic EL element, an inorganic EL element, etc. are mentioned, Especially, an organic EL element is especially preferable.

Below, one embodiment of the method of manufacturing a display element using the adhesive agent for display elements of this invention is demonstrated.
In this embodiment, after applying the adhesive for display elements of the present invention to at least one moisture-proof substrate, irradiating the adhesive for display elements with light, the other moisture-proof substrate is bonded, After curing, the adhesive for the display element is cured. In addition, after irradiating the display element adhesive of the present invention with light, this display element adhesive is applied to at least one moisture-proof substrate, the other moisture-proof substrate is bonded, and then post-cured. The display element adhesive may be cured, or after irradiating the display element adhesive of the present invention with light, the display element adhesive is filled between both moisture-proof substrates, and thereafter It may be cured to cure the display element adhesive. In addition, it is preferable to perform post-curing of the adhesive for display elements irradiated with light at the temperature of 100 degrees C or less. When post-curing is performed at a temperature exceeding 100 ° C., the element may be deteriorated by the influence of heat.
According to such a method, it is not necessary to irradiate light from above the moisture-proof substrate, and the element sandwiched by the moisture-proof substrate does not deteriorate due to the influence of light. Moreover, even if both moisture-proof base materials are opaque and light-impermeable, adhesion or sealing can be performed without hindrance.

The moisture-proof substrate is not particularly limited, and examples thereof include glass substrates such as soda glass and alkali-free glass; metal substrates such as stainless steel and aluminum; polyethylene trifluoride, polytrifluoroethylene chloride (PCTFE), Polyfluorinated ethylene polymers such as polyvinylidene fluoride (PVDF), copolymers of PVDF and PCTFE, copolymers of PVDF and polyfluoroethylene chloride; polyimides; polycarbonates; cycloolefin resins such as dicyclopentadiene; Examples thereof include polyesters such as polyethylene terephthalate; resin substrates such as polyethylene and polystyrene.

The method for applying the adhesive for display elements of the present invention on the moisture-proof substrate is not particularly limited. For example, it may be applied around the moisture-proof substrate, or may be applied to the entire surface of the moisture-proof substrate. May be. In addition, a capillary phenomenon is used to suck up the adhesive for display elements that has been activated in advance between two moisture-proof substrates, or a display that has been activated in advance by applying vacuum between the moisture-proof substrates. The display element adhesive may be filled between moisture-proof substrates by a method of sucking up the element adhesive.

The light source used for activating the adhesive for display elements of the present invention is not particularly limited, and examples thereof include microwaves, infrared rays, visible light, ultraviolet rays, X-rays, γ rays, etc. Ultraviolet light which is simple and can obtain relatively high energy is preferably used. Particularly preferably used is ultraviolet light having a wavelength of 200 to 400 nm. Examples of the light source for irradiating with ultraviolet rays include appropriate light sources such as a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, and a xenon lamp.

According to the present invention, a photocurable resin composition having a low curing shrinkage ratio, good transparency, high heat resistance, low viscosity and good handleability, and light used for the photocurable resin composition There can be provided a cationic polymerization initiator, an adhesive for display elements containing the photocurable resin composition, and a display element using the adhesive.

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

(Production of ortho spiro ester compound)
A four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel was charged with 50 g of methylene chloride and 17.2 g (0.2 mol) of γ-butyrolactone, and boron trifluoride − while cooling this solution to 10 ° C. 0.80 mL (0.0062 mol) of diethyl ether complex was added. Next, 26.0 g (0.1 equivalent) of the epoxy resin (R ¹⁵ , R ¹⁶ = H, epoxy equivalent 260) represented by the general formula (7) while maintaining the reaction solution temperature at 5 to 10 ° C. A mixture of 200 g of methylene chloride was added dropwise over 5 hours with stirring to carry out the reaction. After completion of the dropwise addition, the mixture was further stirred for 3 hours while keeping the reaction solution temperature constant, and 0.72 g (0.0072 mol) of triethylamine (reaction terminator) was added.
Next, in order to remove excess γ-butyrolactone, the reaction solution was washed twice with 500 mL of a 6% aqueous sodium hydroxide solution and then twice with 500 mL of distilled water. The organic layer is separated and dehydrated with magnesium sulfate, and then the obtained organic layer is desolvated to remove the orthospiroester compound A [in the general formula (5), R ¹⁵ , R ¹⁶ = H, m = 1.13. (Average), q = 4]. The yield of the obtained product was 30.4 g (yield: 88%).

(Cyclic carbonate compound)
A cyclic carbonate compound A represented by the following formula (10) and a cyclic carbonate compound B represented by the following chemical formula (11) were used.

(Photocationic polymerization initiator)
A 10 wt% aqueous dispersion of sodium tetrakis (pentafluorophenyl) borate was added dropwise to an aqueous solution (10 wt%) containing 200 mg of (Diphenyl [4- (phenylthio) phenyl] sulfonium) bromide at room temperature. . Then, centrifugation was performed 5 times, the produced | generated deposit was separated by filtration, and after refine | purifying, it dried and synthesize | combined the photocationic polymerization initiator. In addition, the obtained photocationic polymerization initiator absorbed light with a wavelength of 300 nm or more. The obtained cationic photopolymerization initiator was used as a cationic photopolymerization initiator (a).

A compound represented by the following formula (12) was used as a photocationic polymerization initiator (b). Here, the anionic portion X ^- is one represented by the formula (4-1).

(Examples 1-6, Comparative Example 1)
According to the composition of Table 1, each material was uniformly stirred and mixed at a stirring speed of 3000 rpm using a homodisper type stirring mixer (Homodisper L type, manufactured by Tokushu Kika Co., Ltd.) to prepare a photocurable resin composition. .

About the obtained photocurable resin composition, the cure shrinkage rate, the glass transition temperature of hardened | cured material, and the minimum transmittance | permeability of hardened | cured material were evaluated by the following method.
The results are shown in Table 1.

(Curing shrinkage)
While measuring the specific gravity at 25 ° C. for the obtained photocurable resin composition, the photocurable resin composition was irradiated with 2000 mJ light at 350 nm using an ultrahigh pressure mercury lamp, and then at 80 ° C. for 30 minutes. Heated to obtain a cured product. The resulting cured product was again measured for specific gravity at 25 ° C., and the volume shrinkage (%) was determined from the difference in specific gravity before and after curing, and this was used as the cure shrinkage.

(Glass transition temperature of cured product)
After applying the photocurable resin composition to the release treatment surface of the polyethylene terephthalate (PET) film subjected to the release treatment using a Baker type applicator so that the thickness of the coating film becomes 100 μm, ultra high pressure Using a mercury lamp, light having an intensity of 40 mW was irradiated for 50 seconds. Then, after leaving at room temperature for 1 hour, it heated at 80 degreeC for 30 minutes, and performed postcuring. Subsequently, the dynamic viscoelasticity measurement of the cured coating film obtained above was performed, and the glass transition temperature (° C.) was measured from the position of the tan δ peak.

(Minimum transmittance of cured product)
Using a baker type applicator, the photocurable resin composition was applied to one glass plate (thickness 0.7 mm) so that the thickness of the coating film was 100 μm, and using an ultrahigh pressure mercury lamp, the strength of 40 mW was applied. After irradiating light for 50 seconds, the other glass plate (thickness 0.7 mm) was bonded together. Then, after leaving at room temperature for 1 hour, it heated at 80 degreeC for 30 minutes, and performed postcuring. Next, using a spectrophotometer (trade name “COLOR ANALYZER TC-1800M”, manufactured by Tokyo Denshoku Co., Ltd.), the transmittance of the joined body obtained above is measured at any wavelength of 380 to 780 nm, Among them, the lowest one was defined as the minimum transmittance (%) at a wavelength of 380 to 780 nm.

From Table 1, it turned out that the photocurable resin composition obtained in the Example has a low curing shrinkage, a high glass transition temperature, and an excellent light transmittance at a wavelength of 380 to 780 nm.

According to the present invention, a photocurable resin composition having a low curing shrinkage ratio, good transparency, high heat resistance, low viscosity and good handleability, and light used for the photocurable resin composition There can be provided a cationic polymerization initiator, an adhesive for display elements containing the photocurable resin composition, and a display element using the adhesive.

Claims (12)

100 parts by weight of a photocationically polymerizable compound having at least one functional group selected from the group consisting of an epoxy group, an oxetanyl group and a vinyl ether group, 20 to 80 parts by weight of an orthospiroester compound and / or a cyclic carbonate compound, and A photocurable resin composition comprising 0.05 to 20 parts by weight of a cationic photopolymerization initiator. The cationic photopolymerization initiator is composed of a cation moiety represented by the following general formula (1), the following general formula (2) or the following general formula (3), and an anion moiety represented by the following general formula (4). The photocurable resin composition according to claim 1, which is a product.

In formulas (1), (2), and (3), R ^{1 to} R ⁶ each represent a monovalent or divalent phenyl group or naphthyl group, and the phenyl group or naphthyl group is linear or branched. Chain C ₁ -C ₁₂ alkyl group, linear or branched C ₁ -C ₁₂ alkoxyl group, halogen atom, —OH
At least one selected from the group consisting of a group, a —COOH group, and a —COO-alkyl ester group, wherein the alkyl moiety is a linear or branched C ₁ -C ₁₂ residue It may be substituted with a group. R ^{1 to} R ⁶ may be the same as or different from each other.

In formula (4), B represents trivalent boron, and at least one of R ^{7 to} R ¹⁰ represents a halogen-substituted aromatic group having 6 to 30 carbon atoms. 2. The cationic photopolymerization initiator comprises a cation moiety represented by the following general formula (2-1) and an anion moiety represented by the following formula (4-1). Or the photocurable resin composition of 2.

In formula (2-1), R ^{11 to} R ¹⁴ are a hydrogen atom, a linear or branched C _{1 to} C ₁₂ alkyl group, a linear or branched C _{1 to} C ₁₂ alkoxyl group, Halogen atom, -OH group,-
It represents at least one group selected from the group consisting of a COOH group and a —COO-alkyl ester group (wherein the alkyl moiety is a linear or branched C _{1 to} C ₁₂ residue). . R ^{11 to} R ¹⁴ may be the same as or different from each other.

The photocationic polymerization initiator is composed of a cation moiety represented by the following general formula (3-1) and an anion moiety represented by the following formula (4-1). Or the photocurable resin composition of 2.

In formula (3-1), R ^{11 to} R ¹³ are each a hydrogen atom, a linear or branched C _{1 to} C ₁₂ alkyl group, a linear or branched C _{1 to} C ₁₂ alkoxyl group, Halogen atom, -OH group,-
It represents at least one group selected from the group consisting of a COOH group and a —COO-alkyl ester group (wherein the alkyl moiety is a linear or branched C _{1 to} C ₁₂ residue). . R ^{11 to} R ¹⁴ may be the same as or different from each other.

Furthermore, 0.1-50 weight part of hardening control agents are contained, The photocurable resin composition of Claim 1, 2, 3 or 4 characterized by the above-mentioned. The photocurable resin composition according to claim 1, wherein the curing shrinkage is 4% or less. 7. The photocurable resin composition according to claim 1, wherein the cured product has a transmittance of 80% or more at a wavelength of 380 to 780 nm measured using a spectrophotometer. Stuff. An adhesive for display elements, comprising the photocurable resin composition according to claim 1, 2, 3, 4, 5, 6 or 7. A display element comprising the adhesive for a display element according to claim 8. A photocation comprising a cation moiety represented by the following general formula (1), the following general formula (2) or the following general formula (3), and an anion moiety represented by the following general formula (4) Polymerization initiator.

In formulas (1), (2), and (3), R ^{1 to} R ⁶ each represent a monovalent or divalent phenyl group or naphthyl group, and the phenyl group or naphthyl group is linear or branched. Chain C ₁ -C ₁₂ alkyl group, linear or branched C ₁ -C ₁₂ alkoxyl group, halogen atom, —OH
At least one selected from the group consisting of a group, a —COOH group, and a —COO-alkyl ester group, wherein the alkyl moiety is a linear or branched C ₁ -C ₁₂ residue It may be substituted with a group. R ^{1 to} R ⁶ may be the same as or different from each other.

In formula (4), B represents trivalent boron, and at least one of R ^{7 to} R ¹⁰ represents a halogen-substituted aromatic group having 6 to 30 carbon atoms. A photocationic polymerization initiator comprising a cation moiety represented by the following general formula (2-1) and an anion moiety represented by the following formula (4-1).

In formula (2-1), R ^{11 to} R ¹⁴ are a hydrogen atom, a linear or branched C _{1 to} C ₁₂ alkyl group, a linear or branched C _{1 to} C ₁₂ alkoxyl group, Halogen atom, -OH group,-
It represents at least one group selected from the group consisting of a COOH group and a —COO-alkyl ester group (wherein the alkyl moiety is a linear or branched C _{1 to} C ₁₂ residue). . R ^{11 to} R ¹⁴ may be the same as or different from each other.

A photocationic polymerization initiator comprising a cation moiety represented by the following general formula (3-1) and an anion moiety represented by the following formula (4-1).

In formula (3-1), R ^{11 to} R ¹⁴ are a hydrogen atom, a linear or branched C _{1 to} C ₁₂ alkyl group, a linear or branched C _{1 to} C ₁₂ alkoxyl group, Halogen atom, -OH group,-
It represents at least one group selected from the group consisting of a COOH group and a —COO-alkyl ester group (wherein the alkyl moiety is a linear or branched C _{1 to} C ₁₂ residue). . R ^{11 to} R ¹⁴ may be the same as or different from each other.