JP6588698B2 - Adhesive for optical element and optical unit using the same - Google Patents

Description

  The present invention relates to an adhesive for optical elements and an optical unit using the same.

  In recent years, demand for portable electronic devices such as mobile phones and smartphones has been increasing. Such an electronic apparatus is equipped with a small and thin imaging unit, and the imaging unit is generally composed of a solid-state imaging device (CCD type image sensor or CMOS type image sensor) and an optical element such as a lens. ing. And in order to improve the resolution, a plurality of lenses are used in a state (optical unit) fixed with an adhesive.

  Reflow soldering (especially lead-free solder is used for the purpose of improving manufacturing efficiency) for the optical unit composed of a plurality of optical elements as described above and the adhesive for bonding the optical elements. It is required to have heat resistance and heat yellowing that can be mounted by soldering).

  As an adhesive for fixing the optical element, the cationic curable adhesive composition does not inhibit the curing by oxygen and the shrinkage at the time of curing is small compared to the radical polymerizable adhesive composition. Preferably used.

  The cationic curable adhesive composition includes a cationic curable compound and a cationic polymerization initiator, and examples of the cationic polymerization initiator include antimony, phosphorus, and borate systems (Patent Documents 1 to 4). . Conventionally, since it has excellent cationic polymerization activity, a cured product can be quickly formed even if it is a thin film having a thickness of 50 μm or less (that is, excellent in thin film curability), and the obtained cured product is a reflow method. Antimony was widely used in that it can retain its shape even under high temperature conditions such as soldering (i.e., excellent heat resistance) and hardly yellows (i.e., excellent heat yellowing). . However, antimony is a compound designated as a deleterious substance, and its safety has been a problem.

An onium salt having PF ₆ ⁻ as an anion is known as a phosphorus system. This is excellent in thin film curability, but there is a problem that the obtained cured product is easily yellowed under high temperature conditions. Further, the special phosphorus system has a problem that it is inferior in thin film curability.

As borates, onium salts having B (C ₆ F ₅ ) ₄ ^- or BF ₄ ^- as anions are known, but onium salts having BF ₄ ^- as anions have low cationic polymerization activity and are thin film curable. The problem was that it was inferior. Further, onium salts having B (C ₆ F ₅ ) ₄ ⁻ as an anion are excellent in thin film curability, but there is a problem that the obtained cured product is easily yellowed under high temperature conditions.

JP 2011-201803 A JP 2014-125507 A Japanese Patent No. 3991667 Japanese Patent No. 5070131

Therefore, the object of the present invention is excellent in thin film curability, and is excellent in heat resistance and heat yellowing by performing light irradiation or heat treatment (that is, retains its shape even under high temperature conditions such as reflow soldering). It is an object of the present invention to provide an adhesive for optical elements that can form a cured product that is capable of forming a cured product that is excellent in adhesiveness.
Another object of the present invention is to provide an optical unit obtained by bonding an optical element with the optical element adhesive, and an optical device including the optical unit.

  As a result of intensive studies to solve the above problems, the present inventors have found that an adhesive for an optical element containing an alicyclic epoxy compound, an oxetane compound, and a specific borate-based cationic polymerization initiator has excellent thin film curability, light It has been found that a cured product excellent in heat resistance, heat yellowing resistance, and adhesiveness can be formed by performing irradiation or heat treatment. The present invention has been completed based on these findings.

［式中、Ｒ¹〜Ｒ¹⁸は同一又は異なって、水素原子、ハロゲン原子、酸素原子若しくはハロゲン原子を含んでいてもよい炭化水素基、又は置換基を有していてもよいアルコキシ基を示す。Ｘは単結合又は連結基を示す］
で表される化合物を含むエポキシ化合物（Ａ）をカチオン硬化性化合物全量の１０〜９０重量％、オキセタン化合物（Ｂ）をカチオン硬化性化合物全量の５〜４０重量％含有し、カチオン重合開始剤として、下記式（c-1）
［（Ｙ）_kＢ（Ｐｈｆ）_4-k］^- （c-1）
［式中、Ｙは置換基（ハロゲン原子を含む基を除く）を有していてもよい、炭素数６〜３０のアリール基又は炭素数４〜３０の複素環式基を示す。Ｐｈｆは水素原子の少なくとも１つが、パーフルオロアルキル基、パーフルオロアルコキシ基、及びハロゲン原子から選択される少なくとも１種で置換されたフェニル基を示す。ｋは１〜３の整数である］
で表されるアニオン部と、下記式（c-2）

［式中、ＡはＳ原子、Ｉ原子、及びＳｅ原子から選択されるｍ価の原子を示す。Ｒ^a、Ｒ^b、Ｒ^cは１価の基であって、同一又は異なって、置換基を有していてもよい、炭素数１〜３０の炭化水素基、炭素数４〜３０の複素環式基、又はこれらが単結合若しくは連結基を介して結合した基である。Ｒ^dは２価の基であって、置換基を有していてもよい、炭素数１〜３０の炭化水素基、炭素数４〜３０の複素環式基、又はこれらが単結合若しくは連結基を介して結合した基である。前記連結基は−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ₂−、−ＮＨ−、−ＮＲ’−（Ｒ’：炭素数１〜５のアルキル基又は炭素数６〜１０のアリール基）、−ＣＯ−、−ＣＯＯ−、−ＣＯＮＨ−、又は炭素数１〜３のアルキレン基である。ｎは０又は１を示す］
で表されるカチオン部を有するオニウムボレート塩（Ｃ）を含有する光学素子用接着剤を提供する。 That is, the present invention provides the following formula (a) as a cationic curable compound.

[Wherein, R ^{1 to} R ¹⁸ are the same or different and each represents a hydrogen atom, a halogen atom, an oxygen atom, a hydrocarbon group that may contain a halogen atom, or an alkoxy group that may have a substituent. . X represents a single bond or a linking group]
The epoxy compound (A) containing a compound represented by the formula: 10 to 90% by weight of the total amount of the cationic curable compound, and the oxetane compound (B) of 5 to 40% by weight of the total amount of the cationic curable compound, as a cationic polymerization initiator , The following formula (c-1)
[(Y) _k B (Phf) _4-k ] ^- (c-1)
[Wherein Y represents an aryl group having 6 to 30 carbon atoms or a heterocyclic group having 4 to 30 carbon atoms, which may have a substituent (excluding a group containing a halogen atom). Phf represents a phenyl group in which at least one hydrogen atom is substituted with at least one selected from a perfluoroalkyl group, a perfluoroalkoxy group, and a halogen atom. k is an integer of 1 to 3]
An anion moiety represented by the following formula (c-2)

[Wherein, A represents an m-valent atom selected from S atom, I atom, and Se atom. R ^a , R ^b , and R ^c are monovalent groups which may be the same or different and may have a substituent, a hydrocarbon group having 1 to 30 carbon atoms, or a heterocyclic ring having 4 to 30 carbon atoms. A formula group or a group in which these are bonded through a single bond or a linking group. R ^d is a divalent group which may have a substituent, a hydrocarbon group having 1 to 30 carbon atoms, a heterocyclic group having 4 to 30 carbon atoms, or a single bond or a linking group. It is a group bonded through The linking group is —O—, —S—, —SO—, —SO ₂ —, —NH—, —NR ′ — (R ′: an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. ), -CO-, -COO-, -CONH-, or an alkylene group having 1 to 3 carbon atoms. n represents 0 or 1]
The adhesive for optical elements containing the onium borate salt (C) which has a cation part represented by these is provided.

In the present invention, the onium borate salt (C) has an anion moiety of [(C ₆ H ₅ ) B (C ₆ F ₅ ) ₃ ] ⁻ , [(C ₆ H ₅ ) B ((CF ₃ CF ₂ ) ₂ C ₆ H ₂ F) ₃ ] ⁻ , or [(C ₆ H ₅ C ₆ H ₄ ) B (C ₆ F ₅ ) ₃ ] ⁻ .

  The present invention also provides the above adhesive for optical elements, wherein the cation portion of the onium borate salt (C) is an arylsulfonium ion.

  The present invention also provides the above adhesive for optical elements, wherein the epoxy compound (A) further contains a glycidyl ether-based epoxy compound.

  The present invention also provides the above-mentioned adhesive for optical elements, which further contains an antioxidant (D).

  The present invention also provides the above adhesive for optical elements, which further contains a filler (E).

  In the present invention, the viscosity [at 25 ° C., at a shear rate of 20 (1 / s)] is 1 to 20 Pa · s, and the TI value at 25 ° C. [viscosity / shear at a shear rate of 2 (1 / s)] The viscosity of the optical element at a speed of 20 (1 / s)] is 1.5 or more.

  The present invention also provides the above-mentioned adhesive for optical elements, which is for bonding glass or epoxy resin.

  The present invention also provides a cured product obtained by curing the above adhesive for optical elements.

  The present invention also provides a cured product obtained by irradiating the adhesive for optical elements with a UV-LED (wavelength: 350 to 450 nm).

  The present invention also provides the cured product having a thickness of 50 μm or less.

  The present invention also provides an optical unit comprising a plurality of optical elements, wherein each optical element is fixed via the cured product.

  The present invention also provides an optical apparatus comprising the optical unit.

  Since the adhesive for optical elements of the present invention has the above-described configuration, it is excellent in thin film curability and forms a cured product excellent in heat resistance, heat yellowing resistance, and adhesiveness by light irradiation or heat treatment. Can do. Therefore, the adhesive for optical elements of the present invention is used for bonding each optical element in an optical unit composed of a plurality of optical elements (for example, bonding a lens to a substrate, bonding a lens and a reflector, a wafer, For example, it can be suitably used for laminating and bonding level lenses. The optical unit obtained by using the adhesive for optical elements of the present invention can maintain the adhesive state even when subjected to the reflow soldering process, and suppresses yellowing of the adhesive part, thereby reducing the optical properties of the optical element. The characteristics can be kept high. Therefore, there is no need to mount the optical unit in a separate process, and it can be mounted on the substrate together with other components by reflow soldering, and the optical device equipped with the optical unit having excellent optical characteristics has excellent work efficiency. Can be manufactured.

(Epoxy compound (A))
The adhesive for optical elements of the present invention contains an epoxy compound (A) as a cationic curable compound. The epoxy compound (A) includes a compound represented by the following formula (a).

R ^{1 to} R ¹⁸ in the formula (a) are the same or different and are a hydrogen atom, a halogen atom, an oxygen atom, a hydrocarbon group which may contain a halogen atom, or an alkoxy group which may have a substituent. Indicates. X represents a single bond or a linking group.

As a halogen atom in R < ¹ > -R < ¹⁸ >, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. can be mentioned, for example.

Examples of the hydrocarbon group in R ^{1 to} R ¹⁸ include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, and a group in which two or more of these are bonded.

Examples of the aliphatic hydrocarbon group include an alkyl group having 1 to 20 carbon atoms (= C _1-20 ) such as methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, isooctyl, decyl, dodecyl group (preferably C _1-10 alkyl group, particularly preferably C _1-4 alkyl group); vinyl, allyl, methallyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl C _2-20 alkenyl groups (preferably C _2-10 alkenyl groups, particularly preferably C _2-4 alkenyl groups) such as 3-pentenyl, 4-pentenyl and 5-hexenyl groups; C ₂ such as ethynyl and propynyl groups _-20 alkynyl group (preferably a C _2-10 alkynyl group, particularly preferably a C _2-4 alkynyl group).

Examples of the alicyclic hydrocarbon group include C _3-12 cycloalkyl groups such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cyclododecyl groups; C _3-12 cycloalkenyl groups such as cyclohexenyl groups; and bicycloheptanyl. And a C _4-15 bridged cyclic hydrocarbon group such as a bicycloheptenyl group.

Examples of the aromatic hydrocarbon group include C _6-14 aryl groups (preferably C _6-10 aryl groups) such as phenyl and naphthyl groups.

As the hydrocarbon group optionally containing an oxygen atom or a halogen atom in R ^{1 to} R ^18, at least one hydrogen atom in the above hydrocarbon group is substituted with a group having an oxygen atom or a group having a halogen atom. The group etc. can be mentioned. Examples of the group having an oxygen atom include hydroxyl group; hydroperoxy group; C _1-10 alkoxy group such as methoxy, ethoxy, propoxy, isopropyloxy, butoxy, isobutyloxy group; C _2-10 such as allyloxy group. An alkenyloxy group; a C _6-14 aryloxy group optionally having a substituent selected from a C _1-10 alkyl group, a C _2-10 alkenyl group, a halogen atom, and a C _1-10 alkoxy group (for example, C _7-18 aralkyloxy groups such as benzyloxy and phenethyloxy groups; C _1-10 acyloxy groups such as acetyloxy, propionyloxy, (meth) acryloyloxy and benzoyloxy groups; methoxy carbonyl, ethoxycarbonyl, propoxycarbonyl, C _1-10 aralkyl such as a butoxycarbonyl group Alkoxycarbonyl group; C _1-10 alkyl group, C _2-10 alkenyl group, a halogen atom, and C _1-10 may have a substituent group selected from an alkoxy group C _6-14 aryloxycarbonyl group ( For example, phenoxycarbonyl, tolyloxycarbonyl, naphthyloxycarbonyl group, etc.); C _7-18 aralkyloxycarbonyl group such as benzyloxycarbonyl group; epoxy group-containing group such as glycidyloxy group; oxetanyl group such as ethyloxetanyloxy group Groups: C _1-10 acyl groups such as acetyl, propionyl and benzoyl groups; isocyanate groups; sulfo groups; carbamoyl groups; oxo groups; and two or more of these are bonded via a single bond or a C _1-10 alkylene group And the like. Examples of the group having a halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

Examples of the alkoxy group in R ^{1 to} R ¹⁸ include C _1-10 alkoxy groups such as methoxy, ethoxy, propoxy, isopropyloxy, butoxy, and isobutyloxy groups.

Examples of the substituent that the alkoxy group may have include, for example, a halogen atom, a hydroxyl group, a C _1-10 alkoxy group, a C _2-10 alkenyloxy group, a C _6-14 aryloxy group, a C _1-10 Acyloxy group, mercapto group, C _1-10 alkylthio group, C _2-10 alkenylthio group, C _6-14 arylthio group, C _7-18 aralkylthio group, carboxyl group, C _1-10 alkoxycarbonyl group, C _{6- 14} aryloxycarbonyl group, C _7-18 aralkyloxycarbonyl group, amino group, mono or di C _1-10 alkylamino group, C _1-10 acylamino group, epoxy group-containing group, oxetanyl group-containing group, C _1-10 And an acyl group, an oxo group, and a group in which two or more of these are bonded through a single bond or a C _1-10 alkylene group.

R ^{1 to} R ¹⁸ are preferably hydrogen atoms.

X in the above formula (a) represents a single bond or a linking group (a divalent group having one or more atoms). Examples of the linking group include a divalent hydrocarbon group, a carbonyl group, an ether bond, an ester bond, an amide group, and a group in which a plurality of these are linked. Examples of the divalent hydrocarbon group include linear or branched C _1-18 alkylene groups such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene groups (preferably linear or branched chain). C _1-3 alkylene group); 1,2-cyclopentylene, 1,3-cyclopentylene, cyclopentylidene, 1,2-cyclohexylene, 1,3-cyclohexylene, 1,4-cyclohexylene, Examples thereof include a C _3-12 cycloalkylene group such as a cyclohexylidene group, and a C _3-12 cycloalkylidene group (preferably a C _3-6 cycloalkylene group and a C _3-6 cycloalkylidene group).

  Representative examples of the compound represented by the above formula (a) include 3,4-epoxycyclohexylmethyl (3,4-epoxy) cyclohexanecarboxylate, (3,4,3 ′, 4′-diepoxy) biphenyl. Cyclohexyl, bis (3,4-epoxycyclohexylmethyl) ether, 1,2-epoxy-1,2-bis (3,4-epoxycyclohexane-1-yl) ethane, 2,2-bis (3,4-epoxy) And cyclohexane-1-yl) propane and 1,2-bis (3,4-epoxycyclohexane-1-yl) ethane. These can be used alone or in combination of two or more.

The compound represented by the above formula (a) is obtained by reacting, for example, a compound represented by the following formula (a ′) with a peracid (for example, peracetic acid) in the double bond portion in the formula (a ′). Can be produced by epoxidizing the. In the following formula (a ′), R ^{1 to} R ¹⁸ and X are the same as described above.

  In addition to the compound represented by the above formula (a), the epoxy compound (A) may contain other epoxy compounds. Other epoxy compounds include, for example, glycidyl ether type epoxy compounds [for example, aromatic glycidyl ether type epoxy compounds such as bisphenol A type diglycidyl ether and bisphenol F type diglycidyl ether; hydrogenated bisphenol A type diglycidyl ether, water Aliphatic glycidyl ether-based epoxy compounds such as bisphenol F-type diglycidyl ether; aliphatic glycidyl ether-based epoxy compounds]; glycidyl ester-based epoxy compounds; glycidyl amine-based epoxy compounds; other than the compounds represented by formula (a) Alicyclic epoxy compounds (for example, compounds having one alicyclic epoxy group in the molecule such as 1,2-epoxy-4-vinylcyclohexane, 1,2: 8,9-diepoxylimonene, 3 or more alicyclic epoxies A compound having an Si group, etc .; a compound in which an epoxy group is directly bonded to the alicyclic ring by a single bond (for example, 1,2-epoxy-4- (2-oxiranyl) of 2,2-bis (hydroxymethyl) -1-butanol ) Cyclohexane adduct (trade name “EHPE3150”, manufactured by Daicel Corporation) and the like); epoxy-modified siloxane compounds and the like. These can be used alone or in combination of two or more. In the present invention, the alicyclic epoxy compound means an alicyclic epoxy group (that is, an epoxy group composed of two adjacent carbon atoms and oxygen atoms constituting the alicyclic ring, such as a cyclohexene oxide group). It is a compound which has this.

  In the present invention, it is particularly preferable that a glycidyl ether-based epoxy compound is contained because the rheology can be easily controlled and the viscosity of the adhesive for optical elements can be adjusted according to the application.

  The content of the epoxy compound (A) in the total amount (100% by weight) of the cationic curable compound contained in the adhesive for optical elements (the total amount when containing two or more types) is 10 to 90% by weight, preferably 20 to 85%. % By weight, particularly preferably 30 to 80% by weight, most preferably 50 to 80% by weight. When content of an epoxy compound (A) is less than the said range, there exists a tendency for the mechanical physical property of the hardened | cured material obtained to fall. On the other hand, when the content of the epoxy compound (A) exceeds the above range, the curability tends to decrease.

  The content of the compound represented by the formula (a) in the total amount (100% by weight) of the cationic curable compound contained in the adhesive for optical elements (the total amount when containing two or more types) is, for example, 10% by weight. Above, preferably 10 to 90% by weight, particularly preferably 20 to 80% by weight, most preferably 30 to 80%. When the content of the compound represented by the formula (a) is less than the above range, the adhesiveness tends to decrease.

(Oxetane compound (B))
The adhesive for optical elements of the present invention contains one or more oxetane compounds as a cationic curable compound.

（式中、Ｒ^eは１価の有機基を示し、Ｒ^fは水素原子又はエチル基を示す。ｔは０以上の整数を示す） The oxetane compound is represented, for example, by the following formula (b).

(Wherein R ^e represents a monovalent organic group, R ^f represents a hydrogen atom or an ethyl group, and t represents an integer of 0 or more)

The monovalent organic group in R ^e includes a monovalent hydrocarbon group, a monovalent heterocyclic group, a substituted oxycarbonyl group (for example, an alkoxycarbonyl group, an aryloxycarbonyl group, an aralkyloxycarbonyl group, a cycloalkyloxy group). Carbonyl group, etc.), substituted carbamoyl groups (eg, N—C _1-10 alkylcarbamoyl group, N—C _6-10 arylcarbamoyl group, etc.), acyl groups (eg, aliphatic acyl groups such as acetyl group; benzoyl groups, etc.) And a monovalent group in which two or more of these are bonded via a single bond or a linking group.

Examples of the monovalent hydrocarbon group include the same examples as R ^{1 to} R ¹⁸ in the above formula (a).

The monovalent hydrocarbon group includes various substituents [for example, halogen atom, oxo group, hydroxyl group, substituted oxy group (for example, C _1-18 alkoxy group, C _6-10 aryloxy group, C ₆ aralkyloxy group). Group, C _1-10 acyloxy group, etc.), carboxyl group, substituted oxycarbonyl group (eg, C _1-10 alkoxycarbonyl group, C _6-10 aryloxycarbonyl group, C _7-18 aralkyloxycarbonyl group, etc.), substituted Or an unsubstituted carbamoyl group (eg, N—C _1-10 alkylcarbamoyl group, N—C _6-10 arylcarbamoyl group, etc.), cyano group, nitro group, substituted or unsubstituted amino group (eg, amino group, mono or Di-C _1-10 alkylamino group, C _1-10 acylamino group, etc.), sulfo group, heterocyclic group, etc.]. The hydroxyl group and carboxyl group may be protected with a protective group commonly used in the field of organic synthesis.

Examples of the heterocyclic ring constituting the heterocyclic group include a heterocyclic ring containing an oxygen atom as a hetero atom (for example, a 4-membered ring such as an oxetane ring; a furan ring, a tetrahydrofuran ring, an oxazole ring, an isoxazole ring, γ- 5-membered ring such as butyrolactone ring; 6-membered ring such as 4-oxo-4H-pyran ring, tetrahydropyran ring, morpholine ring; benzofuran ring, isobenzofuran ring, 4-oxo-4H-chromene ring, chroman ring, isochroman ring 3-oxatricyclo [4.3.1.1 ^4,8 ] undecan-2-one ring, 3-oxatricyclo [4.2.1.0 ^4,8 ] nonane-2- A bridged ring such as an on-ring), a heterocyclic ring containing a sulfur atom as a hetero atom (for example, a 5-membered ring such as a thiophene ring, a thiazole ring, an isothiazole ring, a thiadiazole ring; 4-oxo; 6-membered ring such as 4H-thiopyran ring; condensed ring such as benzothiophene ring), heterocycle containing nitrogen atom as a hetero atom (for example, pyrrole ring, pyrrolidine ring, pyrazole ring, imidazole ring, triazole ring, etc.) Ring: 6-membered ring such as pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperidine ring, piperazine ring; condensed ring such as indole ring, indoline ring, quinoline ring, acridine ring, naphthyridine ring, quinazoline ring, purine ring, etc. And the like. Examples of the monovalent heterocyclic group include groups in which one hydrogen atom has been removed from the above structural formula of the heterocyclic ring.

In addition to the substituent that the hydrocarbon group may have, the heterocyclic group may be an alkyl group (eg, a C _1-4 alkyl group such as a methyl group or an ethyl group), C _3-12 cycloalkyl, and the like. Group and a substituent such as C _6-14 aryl group (for example, phenyl group, naphthyl group, etc.).

  Examples of the linking group include a carbonyl group (—CO—), an ether bond (—O—), a thioether bond (—S—), an ester bond (—COO—), an amide bond (—CONH—), and a carbonate bond. (-OCOO-), a silyl bond (-Si-), and a group in which a plurality of these are linked.

  Said t shows an integer greater than or equal to 0, for example, 0-12, Preferably it is 1-6.

  Examples of the compound represented by the formula (b) include 3-methoxyoxetane, 3-ethoxyoxetane, 3-propoxyoxetane, 3-isopropoxyoxetane, 3- (n-butoxy) oxetane, and 3-isobutoxyoxetane. 3- (s-butoxy) oxetane, 3- (t-butoxy) oxetane, 3-pentyloxyoxetane, 3-hexyloxyoxetane, 3-heptyloxyoxetane, 3-octyloxyoxetane, 3- (1-propenyloxy ) Oxetane, 3-cyclohexyloxyoxetane, 3- (4-methylcyclohexyloxy) oxetane, 3-[(2-perfluorobutyl) ethoxy] oxetane, 3-phenoxyoxetane, 3- (4-methylphenoxy) oxetane, 3 -(3-Chloro-1-pro Xyl) oxetane, 3- (3-bromo-1-propoxy) oxetane, 3- (4-fluorophenoxy) oxetane and compounds represented by the following formulas (b-1) to (b-16) Can do.

  Examples of the oxetane compound include “Aron oxetane OXT-101”, “Aron oxetane OXT-121”, “Aron oxetane OXT-212”, “Aron oxetane OXT-211”, “Aron oxetane OXT-213”, “Aron oxetane”. Commercially available products such as “OXT-221”, “Aron oxetane OXT-610” (manufactured by Toagosei Co., Ltd.), and “ETERRNACOLL OXBP” (manufactured by Ube Industries, Ltd.) can be used.

  The content of the oxetane compound in the total amount (100% by weight) of the cationic curable compound contained in the adhesive for optical elements (the total amount when containing two or more kinds) is 5 to 40% by weight, preferably 10 to 40% by weight, Particularly preferred is 10 to 30% by weight, and most preferred is 20 to 30% by weight. Since the adhesive for optical elements of the present invention contains an oxetane compound in the above range, it is excellent in curability. When content of an oxetane compound is less than the said range, there exists a tendency for sclerosis | hardenability to fall. On the other hand, when the content of the oxetane compound exceeds the above range, the mechanical properties of the obtained cured product tend to decrease.

(Other cationic curable compounds)
The adhesive for optical elements of the present invention may contain other cationic curable compounds (for example, vinyl ether compounds) in addition to the above epoxy compounds and oxetane compounds, but the content of other cationic curable compounds. Is, for example, 30% by weight or less, preferably 20% by weight or less, particularly preferably 10% by weight or less, based on the total amount (100% by weight) of the cationic curable compound contained in the adhesive for optical elements. When the content of other cationic curable compounds exceeds the above range, the effect of the present invention tends to be difficult to obtain.

(Onium borate salt (C))
The cationic polymerization initiator is a compound having a function of generating an acid by light irradiation or heat treatment to promote polymerization of the cationic curable compound, a cation moiety that absorbs light or heat, an acid generation source, It is comprised by the anion part which becomes.

で表されるオニウムボレート塩（Ｃ）を含有する。そのため、本発明の光学素子用接着剤は薄膜硬化性に優れ、光照射又は加熱処理を施すことにより耐熱性及び耐熱黄変性に優れた硬化物を形成することができる。 The adhesive for optical elements of the present invention has the following formula (c) as a cationic polymerization initiator.

The onium borate salt (C) represented by these is contained. Therefore, the adhesive for optical elements of the present invention is excellent in thin film curability and can form a cured product excellent in heat resistance and heat yellowing resistance by light irradiation or heat treatment.

The onium borate salt (C) of the present invention includes a cationic polymerization initiator described in JP 2011-201803 A. The onium borate salt (C) represented by the above formula (c) contains (n + 1) onium counter ions represented by Z ⁻ in one molecule as an anion portion, and (n + 1) Z ions. ^At least one of-is a borate anion represented by the following formula (c-1).

(Anion part)
The anion part of the onium borate salt of the present invention contains at least a borate anion represented by the following formula (c-1).
[(Y) _k B (Phf) _4-k ] ^- (c-1)
(In the formula, Y represents an aryl group having 6 to 30 carbon atoms or a heterocyclic group having 4 to 30 carbon atoms which may have a substituent (excluding a group containing a halogen atom). Phf represents hydrogen. And at least one of the atoms represents a phenyl group substituted with at least one selected from a perfluoroalkyl group, a perfluoroalkoxy group, and a halogen atom (k is an integer of 1 to 3).

  Examples of the aryl group having 6 to 30 carbon atoms in Y include a phenyl group, a biphenylyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group.

Examples of the heterocyclic group having 4 to 30 carbon atoms in Y include the same examples as the monovalent heterocyclic group represented by R ^e in formula (b).

Y may have one or more substituents. The substituent is a group other than a group containing a halogen atom. For example, a C _1-12 alkyl group, a C _3-6 cycloalkyl group, a C _1-6 alkoxy group, a C _1-6 alkylthio group, a C _6-12 Examples thereof include an arylthio group, a C _2-7 alkylcarbonyl group, a C _2-7 alkoxycarbonyl group, a phenyl group, and a benzoyl group. When Y has two or more substituents, these substituents may be the same or different.

The perfluoroalkyl group is preferably a C _1-8 (preferably C _1-4 ) perfluoroalkyl group, such as trifluoromethyl, pentafluoroethyl, heptafluoropropyl, nonafluorobutyl, perfluoropentyl, perfluoro Linear C _1-8 (preferably C _1-4 ) perfluoroalkyl group such as fluorooctyl group; branched C _3-8 (preferably C _3-4 ) such as heptafluoroisopropyl and nonafluoroisobutyl groups Perfluoroalkyl groups; C _3-8 (preferably C _3-4 ) perfluorocycloalkyl groups such as perfluorocyclopropyl and perfluorocyclobutyl groups.

The perfluoroalkoxy group is preferably a C _1-8 (preferably C _1-4 ) perfluoroalkoxy group, such as trifluoromethoxy, pentafluoroethoxy, heptafluoropropoxy, nonafluorobutoxy, perfluoropentyloxy, Linear C _1-8 such as perfluorooctyloxy group (preferably C _1-4 ) perfluoroalkoxy group; branched C _3-8 such as heptafluoroisopropoxy, nonafluoroisobutoxy group (preferably C _3-4 ) and a perfluoroalkoxy group.

  As said halogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom etc. can be mentioned, for example.

Y is preferably an aryl group having 6 to 30 carbon atoms, particularly preferably a phenyl group (C ₆ H ₅ ) or a biphenylyl group (C ₆ H ₅ C ₆ H ₄ ).

Examples of Phf include a pentafluorophenyl group (C ₆ F ₅ ), a trifluorophenyl group (C ₆ H ₂ F ₃ ), a tetrafluorophenyl group (C ₆ HF ₄ ), and a trifluoromethylphenyl group (CF ₃ C ₆ H _4), bis (trifluoromethyl) phenyl group _{((CF 3) 2 C 6} H 3), pentafluoroethyl phenyl group _{(CF 3 CF 2 C 6 H} 4), bis (pentafluoroethyl) phenyl group ( (CF ₃ CF ₂ ) ₂ C ₆ H ₃ ), fluoro-trifluoromethylphenyl group (CF ₃ C ₆ H ₃ F), fluoro-bis (trifluoromethyl) phenyl group ((CF ₃ ) ₂ C ₆ H ₂ F), fluoro - pentafluoroethyl phenyl group - ani a _{(CF 3 CF 2 C 6 H} 3 F), fluoro-bis (pentafluoroethyl) phenyl group _{((CF 3 CF 2) 2} C 6 H 2 F) , etc. Rukoto can. In the present invention, pentafluorophenyl group (C ₆ F ₅ ), fluoro-bis (pentafluoroethyl) is particularly preferable in that it is excellent in thin film curability and the obtained cured product is particularly excellent in heat resistance and heat yellowing resistance. ) A phenyl group ((CF ₃ CF ₂ ) ₂ C ₆ H ₂ F) is preferred.

Among the anion moieties, [(C ₆ H ₅ ) B (C ₆ F ₅ ) ₃ ] ⁻ , [(C ₆ H ₅ ) B ((CF ₃ CF ₂ ) ₂ C ₆ H ₂ F) ₃ ] ⁻ , [(C ₆ H ₅ C ₆ H ₄ ) B (C ₆ F ₅ ) ₃ ] ^{− and the} like are preferable.

The onium borate salt of the present invention has (n + 1) anions, of which at least one is a borate anion represented by the above formula (c-1), and the rest may be other anions. . Other anions include, for example, halogen ions such as F ⁻ , Cl ⁻ , Br ⁻ and I ⁻ ; OH ⁻ ; ClO ₄ ⁻ ; FSO ₃ ⁻ , ClSO ₃ ⁻ , CH ₃ SO ₃ ⁻ , C ₆ H ₅ SO ₃ ⁻ , C ₆ F ₅ SO ₃ ⁻ , CF ₃ SO ₃ ^{− and} other sulfonate ions; HSO ₄ ⁻ and SO ₄ ^{2− and} other sulfate ions; HCO ₃ ⁻ and CO ₃ ^{2− and} other carbonate ions; H ₂ Phosphate ions such as PO ₄ ⁻ , HPO ₄ ²⁻ , PO ₄ ³⁻ ; PF ₆ ⁻ , PF ₅ OH ⁻ , PF ₃ (CF ₃ ) ₃ ⁻ , PF ₃ (C ₂ F ₅ ) ₃ ⁻ , PF ₃ (C ₃ F _{7) 3} ^- or the like of fluorophosphate ^{_{ion; BF 4 -, B (C}} 6 F 5) 4 -, B (C 6 H 4 CF 3) 4 - borate ion such as; AlCl ₄ ^-; BiF _6- ^{and the} like can be mentioned.

［式中、ＡはＳ原子、Ｉ原子、及びＳｅ原子から選択されるｍ価の原子を示す。Ｒ^a、Ｒ^b、Ｒ^cは１価の基であって、同一又は異なって、置換基を有していてもよい、Ｃ_1-30炭化水素基、Ｃ_4-30複素環式基、又はこれらが単結合若しくは連結基を介して結合した基である。Ｒ^dは２価の基であって、置換基を有していてもよい、Ｃ_1-30炭化水素基、Ｃ_4-30複素環式基、又はこれらが単結合若しくは連結基を介して結合した基である。前記連結基は−Ｏ−、−Ｓ−、−ＳＯ−、−ＳＯ₂−、−ＮＨ−、−ＮＲ’−（Ｒ’：Ｃ_1-5アルキル基又はＣ_6-10アリール基）、−ＣＯ−、−ＣＯＯ−、−ＣＯＮＨ−、又はＣ_1-3アルキレン基である。ｎは０又は１を示す］ (Cation part)
The cation moiety of the onium borate salt of the present invention is represented by the following formula (c-2).

[Wherein, A represents an m-valent atom selected from S atom, I atom, and Se atom. R ^a , R ^b and R ^c are monovalent groups which may be the same or different and may have a substituent, a C _1-30 hydrocarbon group, a C _4-30 heterocyclic group, or These are groups bonded through a single bond or a linking group. R ^d is a divalent group which may have a substituent, a C _1-30 hydrocarbon group, a C _4-30 heterocyclic group, or a bond thereof via a single bond or a linking group It is a group. The linking group is —O—, —S—, —SO—, —SO ₂ —, —NH—, —NR′— (R ′: C _1-5 alkyl group or C _6-10 aryl group), —CO -, - COO -, - CONH- , or a C _1-3 alkylene group. n represents 0 or 1]

  A is an m-valent (m = 1-2) atom selected from S (sulfur) atoms (m = 2), I (iodine) atoms (m = 1), and Se (selenium) atoms (m = 2). Indicates. As A in the present invention, an S atom or an I atom is preferable, and an S atom is particularly preferable in terms of excellent versatility.

Examples of the monovalent C _1-30 hydrocarbon group in R ^a , R ^b , and R ^c include C _6-30 aryl groups such as a phenyl group, a naphthyl group, an anthracenyl group, and a phenanthrenyl group; methyl, ethyl, propyl, Linear or branched C _1-30 (preferably C _1-8 ) alkyl group such as isopropyl group: C _2-30 (preferably C _2-8) such as vinyl, allyl, 1-propenyl, isopropenyl ) Alkenyl group; C _2-30 (preferably C _2-8 ) alkynyl group such as ethynyl, 1-propynyl, 2-propynyl, 1-butynyl group and the like.

Examples of the monovalent C _4-30 heterocyclic group for R ^a , R ^b , and R ^c include the same examples as the monovalent heterocyclic group for R ^e in formula (b).

The m R ^{b s} may be the same or different.

In the monovalent group bonded through a single bond or a linking group in R ^a , R ^b , and R ^c , two or more groups selected from a hydrocarbon group and a heterocyclic group are bonded through a single bond or a linking group. A monovalent group bonded to each other, and examples thereof include a group represented by the following formula.

R ^a , R ^b , and R ^c may have one or more substituents. As the substituent, for example, C _1-18 straight or branched chain alkyl group; C _3-18 cycloalkyl group; a hydroxyl group; C _1-18 straight or branched chain alkoxy groups; C _{2- 18} linear or branched alkylcarbonyl group; C _6-11 arylcarbonyl group; C _2-19 linear or branched alkoxycarbonyl group; C _6-11 aryloxycarbonyl group; C _6-11 arylthio C _1-19 linear or branched acyloxy group; C _6-20 arylthio group; C _1-18 linear or branched alkylthio group; C _6-10 aryl group; C _4-20 complex Cyclic group; C _6-20 aryloxy group; C _1-18 linear or branched alkylsulfinyl group; C _6-10 arylsulfinyl group; C _1-18 linear or branched alkylsulfonyl group; C _6-10 arylsulfonyl group; C _1-12 alkylene group; glycidyl Oxy group; oxetanylmethyl group; vinyloxy ethoxy; amino group; C _1-5 alkyl group and / or a C _6-10 amino group is mono- or disubstituted with an aryl group; a cyano group; a nitro group; and a halogen An atom etc. can be mentioned.

R ^d is a divalent group which may have a substituent, a C _1-30 hydrocarbon group, a C _4-30 heterocyclic group, or a bond thereof via a single bond or a linking group And a group obtained by removing one hydrogen atom from the structural formula of a monovalent group in R ^a , R ^b , and R ^c .

Examples of the cation having the function of absorbing light in the cation represented by the formula (c-2) include triphenylsulfonium, tri-p-tolylsulfonium, tri-o-tolylsulfonium, tris (4-methoxy Phenyl) sulfonium, 1-naphthyldiphenylsulfonium, 2-naphthyldiphenylsulfonium, tris (4-fluorophenyl) sulfonium, tri-1-naphthylsulfonium, tri-2-naphthylsulfonium, tris (4-hydroxyphenyl) sulfonium, 4- (Phenylthio) phenyldiphenylsulfonium, 4- (p-tolylthio) phenyldi-p-tolylsulfonium, 4- (4-methoxyphenylthio) phenylbis (4-methoxyphenyl) sulfonium, 4- (phenylthio) phenyl (4-fluorophenyl) sulfonium, 4- (phenylthio) phenylbis (4-methoxyphenyl) sulfonium, 4- (phenylthio) phenyldi-p-tolylsulfonium, bis [4- (diphenylsulfonio) phenyl] sulfide, bis [4- {bis [4- (2-hydroxyethoxy) phenyl] sulfonio} phenyl] sulfide, bis {4- [bis (4-fluorophenyl) sulfonio] phenyl} sulfide, bis {4- [bis (4-methyl) Phenyl) sulfonio] phenyl} sulfide, bis {4- [bis (4-methoxyphenyl) sulfonio] phenyl} sulfide, 4- (4-benzoyl-2-chlorophenylthio) phenylbis (4-fluorophenyl) sulfonium, 4- (4-Benzoyl-2-chloroph Nylthio) phenyldiphenylsulfonium, 4- (4-benzoylphenylthio) phenylbis (4-fluorophenyl) sulfonium, 4- (4-benzoylphenylthio) phenyldiphenylsulfonium, 7-isopropyl-9-oxo-10-thia- 9,10-dihydroanthracen-2-yl-di-p-tolylsulfonium, 7-isopropyl-9-oxo-10-thia-9,10-dihydroanthracen-2-yl-diphenylsulfonium, 2-[(di- p-tolyl) sulfonio] thioxanthone, 2-[(diphenyl) sulfonio] thioxanthone, 4- [4- (4-t-butylbenzoyl) phenylthio] phenyldi-p-tolylsulfonium, 4- [4- (4-t- Butylbenzoyl) phenylthio] phenyldiphe Nylsulfonium, 4- [4- (benzoylphenylthio)] phenyl-di-p-tolylsulfonium, 4- [4- (benzoylphenylthio)] phenyldiphenylsulfonium, 5- (4-methoxyphenyl) thiantrenium, 5-phenylthientrenium, 5-tolylthanthrenium, 5- (4-ethoxyphenyl) thiantrenium, 5- (2,4,6-trimethylphenyl) thiantrenium, [4- (4-biphenylyl Rulthio) phenyl] -4-biphenylylphenylsulfonium, arylsulfonium ions such as [4- (2-thioxanthonylthio) phenyl] phenyl-2-thioxanthonylsulfonium [particularly A in the formula (c-2) A group bonded to ⁺ (eg, R ^a , R ^b , R ^c , R ^d ) is a C _6-30 aryl group or two or more A triarylsulfonium ion, which is a group in which an aryl group is bonded via a single bond or a linking group, is preferable in terms of versatility, and in particular, 4- (phenylthio) phenyldiphenylsulfonium, bis [4- (diphenylsulfonio) phenyl. Sulfide, [4- (4-biphenylylthio) phenyl] -4-biphenylylphenylsulfonium, and [4- (2-thioxanthonylthio) phenyl] phenyl-2-thioxanthonylsulfonium are preferred.

Examples of the cation having a function of absorbing heat in the cation represented by the formula (c-2) include 4-hydroxyphenyl-methyl-benzylsulfonium, 4-hydroxyphenyl-methyl- (2-methyl). Arylsulfonium ions such as benzyl) sulfonium, 4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium, p-methoxycarbonyloxyphenyl-benzyl-methylsulfonium [particularly, groups bonded to A ⁺ in formula (c-2) One group selected from (for example, R ^a , R ^b , R ^c , R ^d ) is a C _6-30 aryl group or a group in which two or more aryl groups are bonded via a single bond or a linking group. Monoarylsulfonium ion].

  As a specific example of a compound having a function of generating an acid upon irradiation with light in the onium borate salt (C) and promoting the polymerization of a cationic curable compound (that is, a photocationic polymerization initiator), 4- (phenylthio) phenyldiphenyl Sulfonium phenyltris (pentafluorophenyl) borate, bis [4- (diphenylsulfonio) phenyl] sulfide phenyltris (pentafluorophenyl) borate, [4- (4-biphenylylthio) phenyl] -4-biphenylylphenylsulfonium Examples thereof include phenyltris (pentafluorophenyl) borate, [4- (2-thioxanthonylthio) phenyl] phenyl-2-thioxanthonylsulfonium phenyltris (pentafluorophenyl) borate, and the like.

  Specific examples of the compound having a function of generating an acid by heat treatment in the onium borate salt (C) and promoting the polymerization of the cationic curable compound (that is, a thermal cationic polymerization initiator) include 4-hydroxyphenyl-methyl- Benzylsulfonium phenyltris (pentafluorophenyl) borate, 4-hydroxyphenyl-methyl- (2-methylbenzyl) sulfonium phenyltris (pentafluorophenyl) borate, 4-hydroxyphenyl-methyl-1-naphthylmethylsulfonium phenyltris (penta Fluorophenyl) borate, p-methoxycarbonyloxyphenyl-benzyl-methylsulfonium phenyltris (pentafluorophenyl) borate and the like.

  The content of the cationic polymerization initiator is, for example, from 0.1 to 10.5 based on 100 parts by weight of the cationic curable compound (the total amount when containing two or more) included in the adhesive for optical elements of the present invention. 0 parts by weight, preferably 0.1 to 5.0 parts by weight, particularly preferably 0.2 to 3.0 parts by weight, and most preferably 0.5 to 2.5 parts by weight. When content of a cationic polymerization initiator is less than the said range, there exists a tendency for sclerosis | hardenability to fall. On the other hand, when the content of the cationic polymerization initiator exceeds the above range, heat-resistant yellowing tends to decrease.

  The content of the onium borate salt (C) is, for example, 0.1 to 10 with respect to 100 parts by weight of the cationic curable compound (the total amount when containing two or more) included in the adhesive for optical elements of the present invention. 0.0 parts by weight, preferably 0.1 to 5.0 parts by weight, particularly preferably 0.2 to 3.0 parts by weight, and most preferably 0.5 to 2.5 parts by weight.

  The adhesive for optical elements of the present invention may contain other cationic polymerization initiators in addition to the onium borate salt (C), but the total cationic polymerization initiator contained in the adhesive for optical elements of the present invention. For example, 50% by weight or more, preferably 70% by weight or more, particularly preferably 80% by weight or more of the onium borate salt (C).

(Other ingredients)
The adhesive for optical elements of the present invention may contain other components in addition to the above cationic curable compound and cationic polymerization initiator as long as the effects of the present invention are not impaired. Other components include, for example, antioxidants, fillers, photosensitizers, antifoaming agents, silane coupling agents, leveling agents, surfactants, flame retardants, ultraviolet absorbers, decolorizing agents, and adhesion-imparting agents. Etc. These can be used alone or in combination of two or more.

  It is preferable that the adhesive for optical elements of this invention contains antioxidant (D) especially at the point from which the effect which improves the heat-resistant yellowing of hardened | cured material is acquired. Examples of the antioxidant include a phenolic antioxidant, a phosphorus antioxidant, a thioester antioxidant, an amine antioxidant, and the like. These can be used alone or in combination of two or more. In the present invention, phenolic antioxidants are particularly preferable because they are particularly effective in improving heat yellowing.

  Examples of the phenolic antioxidant include pentaerythritol tetrakis [3 (3,5-di-t-butyl-4-hydroxyphenyl) propionate], thiodiethylene bis [3- (3,5-di-t-butyl). -4-hydroxyphenyl) propionate], octadecyl 3- (3,5-di-t-butyl-4-hydroxyphenyl) propanoate, N, N'-hexamethylenebis [3- (3,5-di-t -Butyl-4-hydroxyphenyl) propionamide], octyl 3- (4-hydroxy-3,5-diisopropylphenyl) propionate, 1,3,5-tris (4-hydroxy-3,5-di-t-) Butylbenzyl) -2,4,6-trimethylbenzene, 2,4-bis (dodecylthiomethyl) -6-methylphenol, calcium bis [ , It may be mentioned 5-di (t-butyl) -4-hydroxybenzyl (ethoxy) phosphinate], and the like. In the present invention, for example, trade names “Irganox 1010”, “Irganox 1035”, “Irganox 1076”, “Irganox 1098”, “Irganox 1135”, “Irganox 1330”, “Irganox 1726”, “Irganox 1726”, “Irganox 1726” Commercial products such as BASF) may be used.

  The content of the antioxidant is, for example, 0.05 to 5.0 parts by weight with respect to 100 parts by weight of the cationic curable compound (the total amount when containing two or more) included in the adhesive for optical elements, Preferably it is 0.1-3.0 weight part.

  Moreover, the adhesive for optical elements of the present invention contains a filler (E) having various functions (for example, insulating properties, strength, viscosity, flame retardancy, conductivity, glitter, antibacterial properties, etc.). Also good. The filler includes an inorganic filler and an organic filler.

  Examples of inorganic fillers include calcium carbonate, magnesium carbonate, clay, kaolin, calcium phosphate, hydroxyapatite, mica, talc, silica (for example, fumed silica, colloidal silica, etc.), quartz powder, glass powder, diatomaceous earth, nepheline sinite. , Cristobalite, wollastonite, aluminum hydroxide, iron oxide, zinc oxide, titanium oxide, alumina, calcium sulfate, barium sulfate, dolomite, silicon carbide, silicon nitride, boron nitride, metal powder, graphite, carbon black, hydroxyapatite silver And zeolite silver. As an organic filler, the powder or granular material of various polymers, such as acrylic rubber, can be mentioned, for example. These can be used alone or in combination of two or more.

  The filler surface may be treated with a surface treatment agent such as a silane coupling agent, for example.

  The shape of the filler is not particularly limited, and may be any of a spherical shape, an elliptical shape, a cylindrical shape, a prismatic shape, and the like. The particle size of the filler can be appropriately selected according to the application within a range not impairing the dispersibility, and the average particle size is, for example, about 0.001 to 50 μm.

  The amount of the filler particles used is, for example, 1 to 15 parts by weight, preferably 5 to 10 parts by weight, based on 100 parts by weight of the cationic curable compound contained in the optical element adhesive (the total amount when containing two or more kinds). Part.

  Moreover, the adhesive for optical elements of this invention contains a silane coupling agent with the said filler (E), improves the dispersibility of a filler, and obtains the hardened | cured material which was further excellent in transparency and adhesiveness. This is preferable.

  The amount of the silane coupling agent used is, for example, about 0.1 to 10 parts by weight with respect to 10 parts by weight of the filler.

(Adhesive for optical elements)
The adhesive for optical elements of the present invention comprises an epoxy compound (A) containing a compound represented by the formula (a) as a cationic curable compound, an oxetane compound (B), and the onium borate salt (C) as a cationic polymerization initiator. ). The adhesive for optical elements of the present invention can be prepared by stirring and mixing the above-mentioned components and other components as necessary at a predetermined ratio and defoaming under vacuum as necessary.

  The viscosity [at 25 ° C., shear rate 20 (1 / s)] of the adhesive for optical elements of the present invention is, for example, 1 to 25 Pa · s, preferably 5 to 20 Pa · s, particularly preferably 5 to 15 Pa · s, Most preferably, it is 10-15 Pa.s. The TI value at 25 ° C. [viscosity at shear rate 2 (1 / s) / viscosity at shear rate 20 (1 / s)] is, for example, 1.5 or more, preferably 1.5 to 4.0. Particularly preferred is 1.5 to 3.0, and most preferred is 1.5 to 2.5. Therefore, it is excellent in applicability. For example, when a dispenser or the like is used, it can be selectively applied in a desired range without dripping from the discharge port and without spreading too much after discharge.

  When the adhesive for optical elements of the present invention contains an onium borate salt (C) having an excellent cation curability and generating an acid upon light irradiation, it is heat-treated by light irradiation. In the case where the onium borate salt (C) having a function of generating an acid is contained, the optical element can be bonded and fixed quickly by heating.

  The light (active energy ray) used for the light irradiation may be any light that promotes the curing of the adhesive for optical elements, such as infrared rays, visible rays, ultraviolet rays, X-rays, electron beams, α rays, β rays, Any of gamma rays or the like can be used. In the present invention, among these, ultraviolet rays are preferable in terms of excellent handleability. For irradiation with ultraviolet rays, for example, UV-LED (wavelength: 350 to 450 nm), high pressure mercury lamp, ultra high pressure mercury lamp, xenon lamp, carbon arc, metal halide lamp, sunlight, laser, and the like can be used.

The dose of light, when irradiated with ultraviolet rays, it is preferable to adjust the accumulated light quantity, for example, in 5000 mJ / cm ² or less (e.g. 2500~5000mJ / cm ^2). Moreover, after light irradiation, it is preferable at room temperature (1-30 degreeC) to stand for about 1 to 48 hours at the point which can improve sclerosis | hardenability.

  The heat treatment is performed, for example, by heating at a temperature of 80 to 180 ° C. for about 15 to 180 minutes.

  Since the adhesive for optical elements of the present invention contains the onium borate salt (C) as a cationic polymerization initiator, it is excellent in thin film curability, for example, with a thickness of 50 μm or less (preferably 10 to 30 μm), and also with light irradiation. When it contains the onium borate salt (C) which has a function which generate | occur | produces an acid by giving, even if it light-irradiates with UV-LED, hardening reaction can be advanced rapidly and hardened | cured material can be formed.

  The cured product of the adhesive for optical elements of the present invention is excellent in heat resistance, and the 5% weight reduction temperature is, for example, 260 ° C. or higher, preferably 280 ° C. or higher, particularly preferably 300 ° C. or higher. The 5% weight loss temperature is obtained by differential thermal-thermogravimetric simultaneous measurement (TG-DTA). Therefore, the shape can be maintained even under high temperature conditions such as reflow soldering.

  The cured product obtained by curing the adhesive for optical elements of the present invention is excellent in transparency, and the yellowness (YI) of the cured product before being subjected to the heat test is, for example, 2.0 or less (preferably 0.5 to 2.0, particularly preferably 0.5 to 1.5). Moreover, the cured product obtained by curing the adhesive for optical elements of the present invention can maintain yellowness and maintain transparency even under high temperature conditions such as soldering by a reflow method, and is subjected to a heat resistance test. The yellowness (YI) of the cured product after the treatment is, for example, 3.0 or less (for example, 0.5 to 3.0), and the upper limit is preferably 2.5, particularly preferably 2.0. In addition, the measuring method of yellowness is as having described in the Example.

  Furthermore, the cured product of the adhesive for optical elements of the present invention is an adherend [for example, polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; high-density polyethylene, linear low-density polyethylene, polypropylene, poly-4. -Polyolefins such as methylpentene-1; liquid crystal polymers (fully aromatic polyesters, etc.), polycarbonate, polystyrene, polysulfone (PSF), polyethersulfone (PES), polyphenylsulfone (PPSU), polyphenylene sulfide, aramid, poly-p -Phenylene terephthalamide, polyamide, polyether ether ketone, polyacrylate, polyarylate, polyphenylene ether, polyphenylene oxide, polyacetal, polymethyl methacrylate, poly Acrylonitrile, polychloroethylene chloride, polytetrafluoroethylene, polyparaxylene, polyetherimide, polyimide, polyvinyl chloride, polyurethane, epoxy resin, xylene resin, guanamine resin, diallyl phthalate resin, vinyl ester resin, phenol Plastics such as resin, unsaturated polyester resin, furan resin, melamine resin and urea resin; metals such as iron, aluminum, copper, titanium, tin and zinc; inorganic substances such as glass, ceramics, concrete and rocks; wood and bamboo ] Excellent adhesiveness can be exhibited, and it can be suitably used particularly for glass and epoxy resin bonding applications. Accordingly, the adhesive for optical elements of the present invention is an optical element partially or entirely composed of glass and / or epoxy resin, more specifically, at least the adherend is composed of glass and / or epoxy resin. It can be suitably used as an adhesive for bonding the optical element.

  Since the adhesive for optical elements of the present invention also has the above characteristics, it can be used for bonding each optical element in an optical unit composed of a plurality of optical elements (for example, for bonding a lens to a substrate, lens and reflector). Can be suitably used for applications such as adhering wafers, and laminating and bonding wafer level lenses.

(Optical unit)
The optical unit of the present invention is an optical unit composed of a plurality of optical elements, and each optical element is bonded and fixed via a cured product of the adhesive for optical elements of the present invention.

  Examples of the optical element include a lens, a reflector, an LED, an organic EL element, a semiconductor laser, a transistor, a solar cell, a CCD image sensor, an optical waveguide, an optical fiber, and alternative glass (for example, a display substrate, a hard disk substrate, and a polarizing film). Etc. are included.

  The optical unit of the present invention includes, for example, an LED substrate to which a lens is bonded, a laminated lens, a lens with a reflector, and the like. Since the optical unit of the present invention has a configuration in which a plurality of optical elements are bonded and fixed with a cured product of the above-mentioned adhesive for optical elements, the adhesive state can be firmly maintained even when subjected to a reflow soldering process. And the yellowing of the bonded portion can be suppressed, and the optical characteristics of the optical element can be kept high.

(Optical device)
The optical device of the present invention is an optical device including the above-described optical unit, and can be manufactured, for example, by mounting the optical unit on a substrate by reflow soldering. Examples of the optical device of the present invention include portable electronic devices such as mobile phones, smartphones, and tablet PCs (personal computers), PCs, infrared sensors, and the like. The optical device of the present invention does not need to mount the optical unit in a separate process, and can be mounted collectively by reflow processing. Therefore, the optical device can be manufactured efficiently and at low cost.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples.

Production Example 1 (Production of (3,4,3 ′, 4′-diepoxy) bicyclohexyl (a-1))
A dehydration catalyst was prepared by stirring and mixing 70 g (0.68 mol) of 95 wt% sulfuric acid and 55 g (0.36 mol) of 1,8-diazabicyclo [5.4.0] undecene-7 (DBU).
Into a 3 L flask equipped with a stirrer, a thermometer, and a distillation pipe filled with a dehydrating agent and kept warm, 1000 g (5.05 mol) of hydrogenated biphenol (4,4′-dihydroxybicyclohexyl), 125 g of the prepared dehydration catalyst (0.68 mol as sulfuric acid) and 1500 g of pseudocumene were added, and the flask was heated. The generation of water was confirmed when the internal temperature exceeded 115 ° C. The temperature was further raised to raise the temperature to the boiling point of pseudocumene (internal temperature 162 to 170 ° C.), and dehydration reaction was carried out at normal pressure. By-product water was distilled off and discharged out of the system through a dehydration tube. The dehydration catalyst was liquid under the reaction conditions and was finely dispersed in the reaction solution. After about 3 hours, almost theoretical amount of water (180 g) was distilled, and the reaction was terminated.
Pseudocumene was distilled off using a 10-stage Oldershaw type distillation column, and the reaction-terminated liquid was distilled at an internal pressure of 10 Torr (1.33 kPa) and an internal temperature of 137 to 140 ° C. to obtain 731 g of bicyclohexyl-3. , 3′-diene was obtained.

The obtained bicyclohexyl-3,3′-diene (243 g) and ethyl acetate (730 g) were charged into a reactor, and nitrogen was blown into the gas phase portion, and the temperature in the reaction system was controlled to 37.5 ° C. Then, 274 g of 30 wt% peracetic acid in ethyl acetate (water content: 0.41 wt%) was added dropwise over about 3 hours. After completion of the dropwise addition, the reaction was terminated by aging at 40 ° C. for 1 hour.
Thereafter, the crude liquid at the end of the reaction was washed with water at 30 ° C., and the low boiling point compound was removed at 70 ° C./20 mmHg to obtain 270 g of a reaction product. The oxirane oxygen concentration of the reaction product was 15.0% by weight.
In ¹ H-NMR measurement, a peak derived from an internal double bond near δ4.5 to 5 ppm disappeared, and a proton peak derived from an epoxy group was confirmed near δ3.1 ppm. The product was confirmed to be (3,4,3 ′, 4′-diepoxy) bicyclohexyl.

Production Example 2 (Production of bis (3,4-epoxycyclohexylmethyl) ether (a-2))
Sodium hydroxide (granular form) (499 g, 12.48 mol) and toluene (727 mL) were added to a 5 L reactor, and after purging with nitrogen, a solution of tetrahydrobenzyl alcohol (420 g, 3.74 mol) in toluene (484 mL) was added. And aged at 70 ° C. for 1.5 hours. Next, tetrahydrobenzyl methanesulfonate (419 g, 2.20 mol) was added and aged under reflux for 3 hours, then cooled to room temperature, water (1248 g) was added to stop the reaction, and liquid separation was performed.
After concentration of the separated organic layer, distillation under reduced pressure was performed to obtain ditetrahydrobenzyl ether as a colorless transparent liquid (yield: 85%). The ¹ H-NMR spectrum of the obtained ditetrahydrobenzyl ether was measured.
¹ H-NMR (CDCl ₃ ): δ 1.23-1.33 (m, 2H), 1.68-1.94 (m, 6H), 2.02-2.15 (m, 6H), 3.26-3.34 (m, 4H), 5.63-7.70 (m, 4H)

The obtained ditetrahydrobenzyl ether (200 g, 0.97 mol), 20% SP-D (acetic acid solution) (0.39 g), and ethyl acetate (669 mL) were added to the reactor, and the temperature was raised to 40 ° C. Subsequently, 29.1% peracetic acid (608 g) was added dropwise over 5 hours. After completion of the dropwise addition, the reaction was completed after aging for 3 hours.
Thereafter, the organic layer was washed three times with an aqueous alkali solution and twice with ion-exchanged water, and then distilled under reduced pressure to obtain bis (3,4-epoxycyclohexylmethyl) ether as a colorless transparent liquid (yield) : 77%).

Production Example 3 (Production of 2,2-bis (3,4-epoxycyclohexane-1-yl) propane (a-3))
36 g of water, 12.0 g of sodium hydrogen sulfate, 500 g of isopropylidene-4,4′-dicyclohexanol (manufactured by Aldrich) as a solvent in a 1 L jacketed flask equipped with a stirrer, a condenser, a thermometer and a nitrogen introduction tube 500 g of Solvesso 150 (manufactured by ExxonMobil) was added and dehydrated at 100 ° C. The reaction was terminated when no more water distilled.
When the reaction solution was analyzed by gas chromatography, 2,2-bis (3,4-cyclohexenyl) propane was produced in a yield of 96%. The obtained reaction solution was washed with 500 mL of ion exchanged water using a separatory funnel, and then the organic layer was distilled under reduced pressure to obtain 387.0 g of colorless and transparent liquid 2,2-bis (3,4-cyclohexenyl) propane. Got. The purity was 96.1%.

100 g of the obtained 2,2-bis (3,4-cyclohexenyl) propane and 30 g of ethyl acetate were charged into a 1 L jacketed flask similar to the above, and the temperature in the reaction system was adjusted while blowing nitrogen into the gas phase. Over about 2 hours so that it might become 30 degreeC, the ethyl acetate solution 307.2g (peracetic acid concentration: 29.1 weight%, water content: 0.47 weight%) of substantially anhydrous acetic acid was dripped. After completion of the dropwise addition, the reaction was terminated by aging at 30 ° C. for 3 hours.
Thereafter, the reaction-terminated liquid was washed with water at 30 ° C. and deboiling was performed at 70 ° C./20 mmHg to obtain 99.4 g of 2,2-bis (3,4-epoxycyclohexane-1-yl) propane.
The properties of the obtained product are oxirane oxygen concentration of 11.3%, viscosity of 3550 cP (25 ° C.), the peak derived from internal double bonds around δ4.5-5 ppm disappears from ¹ H-NMR, and δ2 It was confirmed that a proton peak derived from an epoxy group was generated in the vicinity of .9 to 3.1 ppm.

Examples 1 to 6 (Example 1 is a reference example) , Comparative Examples 1 to 4
Each component described in the following Table 1 was blended according to the blending composition (unit: parts by weight), and stirred and mixed at room temperature using a rotation and revolution mixer to obtain a uniform and transparent adhesive for optical elements. The obtained adhesive for optical elements was evaluated according to the following evaluation method.

[viscosity]
The viscosity (Pa · s) was measured using a rheometer (trade name “PHYSICA UDS200”, manufactured by Anton Paar) at a temperature of 25 ° C. and a rotation speed of 20 / sec.

[Thixotropic properties]
The thixotropy was measured by using a rheometer (trade name “PHYSICA UDS200”, manufactured by Anton Paar), increasing the rotation speed to 50 / sec at 25 ° C., and confirming that the viscosity had sufficiently decreased. The speed was gradually decreased, and evaluation was performed by calculating the TI value by the following formula from the viscosity at a shear rate of 2 (1 / s) and the viscosity at a shear rate of 20 (1 / s).
TI value = [viscosity at shear rate 2 (1 / s) / viscosity at shear rate 20 (1 / s)]

[Curing property]
A 0.03 mm spacer was placed on both ends of a slide glass (trade name “S9112” manufactured by Matsunami Glass Industry Co., Ltd.), and an optical element adhesive was dropped in the middle. The adhesive for optical elements was spread using a squeegee to a thickness of 0.03 mm, and light irradiation was performed using a UV-LED or a high-pressure mercury lamp under the following conditions. After light irradiation, it was left at room temperature for 60 minutes to obtain a cured product.
About the obtained hardened | cured material, the tackiness of the surface was judged by palpation, and sclerosis | hardenability was evaluated by the following reference | standard.
Evaluation criteria ○: There was no tackiness on the surface, and the surface shape of the cured product did not change even after palpation. Δ: Although there was no surface tackiness, the surface shape of the cured product changed by palpation. Had sex

Light irradiation conditions <UV-LED>
Irradiation device: Trade name “ZUV-C20H” (made by OMRON Corporation)
Wavelength: 365nm
Irradiation intensity: 100 mW / cm
Integrated irradiation dose: 3000 mJ / cm ²
<High pressure mercury lamp>
Irradiation device: Product name "LC-8" (manufactured by Hamamatsu Photonics)
Irradiation intensity: 100 mW / cm
Integrated irradiation dose: 3000 mJ / cm ²

[transparency]
A spacer made of Teflon (registered trademark) having a length of 20 mm × width of 20 mm × thickness of 0.1 mm was prepared, and sandwiched between slide glasses (trade name “S2111”, manufactured by Matsunami Glass Co., Ltd.). An adhesive for an optical element was cast in the gap, and light was irradiated in the same manner as above to obtain a cured product. After light irradiation, the yellowness (YI) of a sample obtained by leaving at room temperature for 60 minutes was measured using a spectrophotometer (trade name “U-3900”, manufactured by Hitachi High-Technologies Corporation). For yellowness (YI), the value of the field of view twice with a D65 light source was read.

[Heat resistant transparency]
Using the same sample as the above [Transparency] evaluation, a heat resistance test based on the reflow temperature profile (maximum temperature: 270 ° C.) described in the JEDEC standard was performed three times in succession using a tabletop reflow oven (manufactured by Thin Apec). After that, yellowness (YI) was measured by the same method as described above.

[Adhesiveness]
A 0.03 mm spacer was placed on both ends of a slide glass (trade name “S2111”, manufactured by Matsunami Glass Industry Co., Ltd.), and an optical element adhesive was dropped in the middle. Using a squeegee, spread the optical element adhesive to a thickness of 0.03 mm, and then an epoxy resin cube (outer diameter: 4 mm x 4 mm x 1 mm, inner diameter: 3.7 mm x 3.7 mm x 0.8 mm, adhesion area: 2.3 mm ² ) was set, and light irradiation was performed in the same manner as described above.
As the epoxy resin cube, a composition obtained by adding 0.5% by weight of a photocation initiator CPI-101A (manufactured by San Apro Co., Ltd.) to CELLOXIDE 2021P (manufactured by Daicel Corp.) has the above shape. The product was molded into a photo-cured product.
About the sample obtained by leaving it at room temperature for 60 minutes or more after light irradiation, using a die shear tester (trade name “4000PXY”, manufactured by DAGE) under the following conditions, the weight of separation of the epoxy resin cube ( The adhesiveness was evaluated from kgf). Five samples were prepared and evaluated based on the average value.
Adhesive measurement conditions Share height: 0.65 mm
Share speed: 500 μm / s

[Heat resistant adhesiveness]
A sample similar to the above [Adhesiveness] evaluation was subjected to a heat resistance test three times in succession based on the reflow temperature profile (maximum temperature: 270 ° C.) described in the JEDEC standard using a tabletop reflow oven (manufactured by Shin-Apec). After that, the adhesion was evaluated by the same method (number of samples: 5) as described above.

※ 比較例３は硬化不十分のため、接着性は評価できなかった。

* Since Comparative Example 3 was insufficiently cured, the adhesion could not be evaluated.

The compound name of each component in Table 1 is as follows.
<Epoxy compound (A)>
CELLOXIDE2021P: 3,4-epoxycyclohexylmethyl (3,4-epoxy) cyclohexanecarboxylate, trade name “CELLOXIDE2021P”, manufactured by Daicel Corporation (a-1): compound obtained by Production Example 1, (3,4 , 3 ′, 4′-diepoxy) bicyclohexyl (a-2): the compound obtained in Production Example 2, bis (3,4-epoxycyclohexylmethyl) ether (a-3): obtained in Production Example 3 Compound, 2,2-bis (3,4-epoxycyclohexane-1-yl) propane YL983U: Bisphenol F type diglycidyl ether, trade name “YL983U”, manufactured by Mitsubishi Chemical Corporation <Oxetane compound (B)>
OXT221: 3-ethyl-3 {[(3-ethyloxetane-3-yl) methoxy] methyl} oxetane, trade name “Aron oxetane OXT-221”, manufactured by Toagosei Co., Ltd. OXT101: 3-ethyl-3-hydroxy Methyl oxetane, trade name “Aron oxetane OXT-101”, manufactured by Toagosei Co., Ltd. <cationic polymerization initiator (C)>
(C-1): 4- (phenylthio) phenyldiphenylsulfonium phenyltris (pentafluorophenyl) borate (c-2): [4- (4-biphenylylthio) phenyl] -4-biphenylylphenylsulfonium phenyltris ( Pentafluorophenyl) borate CPI-100P: 4- (phenylthio) phenyldiphenylsulfonium, 50% propylene carbonate solution of hexafluorophosphate, trade name “CPI-100P”, CPI-200K by San Apro Co., Ltd .: 4- (phenylthio) phenyl Propylene carbonate solution of diphenylsulfonium tris (pentafluoroethyl) trifluorophosphate, trade name “CPI-200K”, manufactured by San Apro Co., Ltd. <Other components>
W-300A: powder made of organic filler, acrylic rubber, average particle size: 0.1 μm, trade name “Methbrene W-300A”, Aerosil 300 manufactured by Mitsubishi Rayon Co., Ltd .: inorganic filler, hydrophilic fumed silica, Average particle size: 0.1 μm, trade name “Aerosil 300”, Nippon Aerosil Co., Ltd. OFS-6040: silane coupling agent, 3-glycidoxypropyltrimethoxysilane, trade name “OFS-6040”, Toray Industries, Inc. IN1010 manufactured by Dow Corning Co., Ltd .: antioxidant, pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], trade name “Irganox 1010”, manufactured by BASF

Claims (10)

As the cationic curable compound, the following formula (a)

[Wherein, R ^{1 to} R ¹⁸ are the same or different and each represents a hydrogen atom, a halogen atom, an oxygen atom, a hydrocarbon group that may contain a halogen atom, or an alkoxy group that may have a substituent. . X represents a single bond or a linking group]
10 to 90% by weight of the total amount of the cation curable compound, and 5 to 40% by weight of the oxetane compound (B) of the total amount of the cation curable compound. , the content of the previous SL epoxy compound (a) and the oxetane compound (B) other than the cationically curable compound is more than 10 wt% of cationically curable compounds the total amount,
As a cationic polymerization initiator, the following formula (c-1)
[(Y) _k B (Phf) _4-k ] ^- (c-1)
[Wherein Y represents an aryl group having 6 to 30 carbon atoms or a heterocyclic group having 4 to 30 carbon atoms, which may have a substituent (excluding a group containing a halogen atom). Phf represents a phenyl group in which at least one hydrogen atom is substituted with at least one selected from a perfluoroalkyl group, a perfluoroalkoxy group, and a halogen atom. k is an integer of 1 to 3]
An anion moiety represented by the following formula (c-2)

[Wherein, A represents an m-valent atom selected from S atom, I atom, and Se atom. R ^a , R ^b , and R ^c are monovalent groups which may be the same or different and may have a substituent, a hydrocarbon group having 1 to 30 carbon atoms, or a heterocyclic ring having 4 to 30 carbon atoms. A formula group or a group in which these are bonded through a single bond or a linking group. R ^d is a divalent group which may have a substituent, a hydrocarbon group having 1 to 30 carbon atoms, a heterocyclic group having 4 to 30 carbon atoms, or a single bond or a linking group. It is a group bonded through The linking group is —O—, —S—, —SO—, —SO ₂ —, —NH—, —NR ′ — (R ′: an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. ), -CO-, -COO-, -CONH-, or an alkylene group having 1 to 3 carbon atoms. n represents 0 or 1]
Containing an onium borate salt (C) having a cation moiety represented by:
Furthermore, a filler (E) is contained,
Viscosity [at 25 ° C., shear rate 20 (1 / s)] is 5 to 15 Pa · s, and TI value at 25 ° C. [viscosity at shear rate 2 (1 / s) / shear rate 20 (1 / s) ) Viscosity at time] is 1.5 to 3.0, and is an adhesive for optical elements mounted on a substrate by reflow soldering. The anion part of the onium borate salt (C) is [(C ₆ H ₅ ) B (C ₆ F ₅ ) ₃ ] ⁻ , [(C ₆ H ₅ ) B ((CF ₃ CF ₂ ) ₂ C ₆ H ₂ F ₃ ) ⁻ or [(C ₆ H ₅ C ₆ H ₄ ) B (C ₆ F ₅ ) ₃ ] ⁻ . The adhesive for optical elements mounted on a substrate by reflow soldering according to claim 1.   The adhesive for optical elements mounted on a substrate by reflow soldering according to claim 1 or 2, wherein the cation portion of the onium borate salt (C) is an arylsulfonium ion.   The adhesive for optical elements mounted on a substrate by reflow soldering according to any one of claims 1 to 3, further comprising an antioxidant (D). It is an object for adhesion | attachment of glass or an epoxy resin, The adhesive agent for optical elements mounted on a board | substrate by the reflow soldering of any one of Claims 1-4 . Hardened | cured material of the adhesive agent for optical elements mounted on a board | substrate by the reflow soldering of any one of Claims 1-5 . The cured product according to claim 6 , wherein the thickness is 50 μm or less. An optical unit composed of a plurality of optical elements, wherein each optical element is fixed via the cured product according to claim 6 or 7 . An optical device comprising the optical unit according to claim 8 . The manufacturing method of the hardened | cured material which irradiates UV-LED (wavelength: 350-450 nm) to the adhesive for optical elements mounted by the reflow soldering of any one of Claims 1-5 , and obtains hardened | cured material .