JP6565160B2 - Curable composition and optical adhesive - Google Patents

Description

The present invention relates to an optical member used when producing an optical element, and a curable composition suitable as an optical adhesive.

A curable composition containing an episulfide compound as a main component is widely used as an optical member or an optical adhesive when producing an optical element. In particular, a high refractive index is highly desired because the degree of freedom in optical design is widened. Examples of applications in which an optical element having a high refractive index is used include a large-aperture optical lens such as a camera lens, a prism, a light guide plate, an achromatic lens (achromatic lens) formed by bonding two lenses, and glass. Examples thereof include a hybrid aspherical lens composed of a composite of resins, a prism having a complicated shape such as a dichroic prism, and a diffraction grating. Optical elements used in these applications require optical properties such as mechanical strength, durability, and colorless transparency as basic performance. Rate has become an important performance. Furthermore, sufficient heat resistance is required for a manufacturing process and a use environment under a high temperature such as a reflow process. In addition, performance suitable for production such as adhesion, curability and viscosity suitable for work is naturally required.

As compounds having a high refractive index, many episulfide compounds containing a high concentration of sulfur atoms in the molecular structure have been found (Patent Documents 1 to 4). For example, the refractive index of a cured product of bis (2,3-epithiopropyl) sulfide is nd = 1.71. The optical material obtained by polymerizing and curing the episulfide compound alone is not sufficiently satisfied with oxidation resistance, and has a tendency to be easily colored yellow in a process that requires long-term storage and heat treatment, A technique for imparting excellent oxidation resistance by blending a thiol compound has been reported (Patent Document 5). However, in these compositions, the glass transition temperature (Tg) has an upper limit of 105 ° C., and when the thiol compounding ratio is increased in order to improve oxidation resistance, the Tg is greatly reduced. Therefore, a resin having an improved heat resistance such that the refractive index is 1.68, the Abbe number is 31 or more, and the Tg is 106 ° C. or more while sufficiently having low yellowness and high transparency as an optical material. It was difficult to get.

JP-A-9-71580 Japanese Patent Laid-Open No. 9-110979 Japanese Patent Laid-Open No. 9-255781 JP 2001-163874 A Japanese Patent Laid-Open No. 10-298287

  Accordingly, an object of the present invention is to provide a curable composition having a high refractive index and an Abbe number as well as a high heat resistance as well as colorless transparency and adhesiveness as an optical member or an optical adhesive used in an optical element. The object is to provide a composition, a cured resin comprising the composition, and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventors have found that a curable composition containing an episulfide compound (component A) and a thiol compound (component B) has a high refractive index and further increased heat resistance. And the present invention has been found to have the necessary performance as a material for optical elements.

According to the present invention, there is provided a curable composition having colorless transparency, high refractive index, Abbe number, and performance as an optical member or optical adhesive used in an optical element such as high heat resistance after curing. can do.

（ｍ１は０〜４の整数、ｍ２は０〜２の整数を表す。） The episulfide compound (component (A)) used in the present invention is a compound having two episulfide groups in the molecule represented by the following formula (1), specifically, bis (β-epithiopropyl). ) Sulfide, bis (β-epithiopropyl) disulfide, bis (β-epithiopropyl) trisulfide, bis (β-epithiopropylthio) methane, 1,2-bis (β-epithiopropylthio) ethane, 1,3-bis (β-epithiopropylthio) propane, 1,2-bis (β-epithiopropylthio) propane, 1,4-bis (β-epithiopropylthio) butane, and bis (β- One or more episulfide compounds selected from the group consisting of (epithiopropylthioethyl) sulfide.

(M1 represents an integer of 0 to 4, and m2 represents an integer of 0 to 2.)

ビス（β−エピチオプロピル）スルフィド Among them, preferred specific examples are bis (β-epithiopropyl) sulfide (formula (2)) and / or bis (β-epithiopropyl) disulfide (formula (3)), and the most preferred specific example is bis ( β-epithiopropyl) sulfide.

Bis (β-epithiopropyl) sulfide

ビス（β−エピチオプロピル）ジスルフィド

Bis (β-epithiopropyl) disulfide

（Ｘは、水素原子に隣接するイオウ原子または酸素原子を有する二価の基を表し、複数のＸは異なっていてもよい。ただし、Ｘのうち少なくとも１つはイオウ原子を有する。Ｚは炭素数１〜３のアルキル基、ハロゲン基、炭素数１〜３のハロゲン化アルキル基、炭素数１〜３のアルコキシ基、アミノ基、ニトロ基、ヒドロホルミル基またはカルボキシル基を表し、複数のＺは異なっていてもよい。ｎ１は異なっていてもよく１〜４の整数を、ｎ２は異なっていてもよく０〜４の整数を、ｎ３は異なっていてもよく０〜４の整数を表す。ただし、ｎ１＋ｎ３≦５の関係である。） The thiol compound (component (B)) used in the present invention is a compound having at least one thiol group in an aromatic skeleton represented by the following formula (4).

(X represents a divalent group having a sulfur atom or an oxygen atom adjacent to a hydrogen atom, and a plurality of X may be different, provided that at least one of X has a sulfur atom. Z is carbon. Represents a C 1-3 alkyl group, a halogen group, a C 1-3 halogenated alkyl group, a C 1-3 alkoxy group, an amino group, a nitro group, a hydroformyl group or a carboxyl group, and a plurality of Z are different N1 may be different and represents an integer of 1 to 4, n2 may be different and represents an integer of 0 to 4, and n3 may be different and represents an integer of 0 to 4. (The relationship is n1 + n3 ≦ 5.)

（Z、ｎ１、ｎ２、ｎ３は式（１）と同じである。Ｒ１、Ｒ２は同一または異なって炭素数１〜４のアルキル基を表す。ｎ４は同一または異なって０〜４の整数を合わす。ｎ５は同一または異なって０〜２の整数を表す。ただし、ｎ４のうち少なくとも一つは１以上の整数である。） The thiol compound represented by the formula (4) is more preferably a thiol compound represented by the formula (5).

(Z, n1, n2, and n3 are the same as those in formula (1). R1 and R2 are the same or different and represent an alkyl group having 1 to 4 carbon atoms. N4 is the same or different and combines an integer of 0 to 4. N5 are the same or different and each represents an integer of 0 to 2, provided that at least one of n4 is an integer of 1 or more.)

R1 and R2 in Formula (5) are the same or different and represent an alkyl group having 1 to 4 carbon atoms. Specifically, it is exemplified by one selected from the following formula (6). In addition, a dotted line means the coupling | bonding with an adjacent group.

As a thiol compound represented by Formula (5), the dithiol compound represented by Formula (7)-(9) or the monothiol compound represented by Formula (10)-(11) is especially preferable. Among these, the dithiol compound represented by Formula (7) is the most preferable.

  You may mix | blend the thiol compound which has 1 or more generally known thiol groups in 1 molecule as an additional component with the curable composition of this invention. Specific examples thereof include methyl mercaptan, ethyl mercaptan, n-propyl mercaptan, n-butyl mercaptan, allyl mercaptan, n-hexyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, n-tetradecyl mercaptan. , N-hexadecyl mercaptan, n-octadecyl mercaptan, cyclohexyl mercaptan, i-propyl mercaptan, t-butyl mercaptan, t-nonyl mercaptan, t-dodecyl mercaptan, phenyl mercaptan, benzyl mercaptan, 3-methylphenyl mercaptan, 4-methyl Phenyl mercaptan, 4-chlorobenzyl mercaptan, 4-vinylbenzyl mercaptan, 3-vinylbenzyl mercaptan, methyl mercapa Topropionate, 2-mercaptoethanol, 3-mercapto-1,2-propanediol, 2-mercapto-1,3-propanediol, mercaptoacetic acid, mercaptoglycolic acid, mercaptopropionic acid, methanedithiol, 1,2-dimercaptoethane 1,2-dimercaptopropane, 1,3-dimercaptopropane, 2,2-dimercaptopropane, 1,4-dimercaptobutane, 1,6-dimercaptohexane, bis (2-mercaptoethyl) ether, Bis (2-mercaptoethyl) sulfide, 1,2-bis (2-mercaptoethyloxy) ethane, 1,2-bis (2-mercaptoethylthio) ethane, 2,3-dimercapto-1-propanol, 1,3 -Dimercapto-2-propanol, 1,2,3-trimerca Topropane, 2-mercaptomethyl-1,3-dimercaptopropane, 2-mercaptomethyl-1,4-dimercaptobutane, 2- (2-mercaptoethylthio) -1,3-dimercaptopropane, 4-mercaptomethyl -1,8-dimercapto-3,6-dithiaoctane, 2,4-dimercaptomethyl-1,5-dimercapto-3-thiapentane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9 -Trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-tri Thiaundecane, 1,1,1-tris (mercaptomethyl) propane, tetrakis (mercaptomethyl) methane, ethylene glyco Bis (2-mercaptoacetate), ethylene glycol bis (3-mercaptopropionate), diethylene glycol bis (2-mercaptoacetate), diethylene glycol bis (3-mercaptopropionate), 1,4-butanediol bis (2- Mercaptoacetate), 1,4-butanediol bis (3-mercaptopropionate), trimethylolpropane tris (2-mercaptoacetate), trimethylolpropane tris (3-mercaptopropionate), trimethylolpropane tris (3 -Mercaptobutyrate), pentaerythritol tetrakis (2-mercaptoacetate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakis (3-merca) Tobutyrate), 1,2-dimercaptocyclohexane, 1,3-dimercaptocyclohexane, 1,4-dimercaptocyclohexane, 1,3-bis (mercaptomethyl) cyclohexane, 1,4-bis (mercaptomethyl) cyclohexane, 2 , 5-bis (mercaptomethyl) -1,4-dithiane, 2,5-bis (2-mercaptoethyl) -1,4-dithiane, 2,5-bis (2-mercaptoethylthiomethyl) -1,4 -Dithian, 2,5-bis (mercaptomethyl) -1-thian, 2,5-bis (2-mercaptoethyl) -1-thian, 2,5-bis (mercaptomethyl) thiophene, 1,2-epithio Mercaptoethane, 1,2-epithio-1,2-dimercaptoethane, 1,2-epithio-1,2,3,4-tetramercapto Tan, 1,2-epithio-3-mercaptopropane, 1,2-epithio-3,3-dimercaptopropane, 1,2-epithio-3,3,3-trimercaptopropane, 2,3-epithio-1 , 4-Dimercaptobutane, 2,3-epithio-1,1,4,4-tetramercaptobutane, 1,2-epithio-5-mercapto-4-thiapentane, 1,2-epithio-5,5-dimercapto -4-thiapentane, 1,2-epithio-5,5,5-trimercapto-4-thiapentane, 1,2: 6,7-diepithio-1,7-dimercapto-5-thiaheptane, 1,2: 6 Aliphatic mercaptans such as 7-diepithio-3,5-dimercapto-5-thiaheptane, 1,2-dimercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercap Tobenzene, o-xylylenedithiol, m-xylylenedithiol, p-xylylenedithiol, 2,2'-dimercaptobiphenyl, 4,4'-dimercaptobiphenyl, bis (4-mercaptophenyl) methane, 2,2 -Bis (4-mercaptophenyl) propane, bis (4-mercaptophenyl) ether, bis (4-mercaptophenyl) sulfide, bis (4-mercaptophenyl) sulfone, bis (4-mercaptomethylphenyl) methane, 2,2 -Aromatic cyclic mercaptans such as bis (4-mercaptomethylphenyl) propane, bis (4-mercaptomethylphenyl) ether, bis (4-mercaptomethylphenyl) sulfide, 4-hydroxythiophenol, mercaptobenzoic acid . Furthermore, thiols such as sulfide oligomers and disulfide oligomers such as dimers to 20-mers of these thiol compounds can be mentioned.

The component (A) and the component (B) may be either a single compound or a mixture of a plurality of compounds, and are not particularly limited.

The ratio of the component (A) in the curable composition of this invention is 25 mass% or more normally, Preferably it is 30 mass% or more, More preferably, it is 32.5 mass% or more. Moreover, the ratio of the component (B) in the curable composition of this invention is 0.5 mass% or more normally, Preferably it is 1 mass% or more, More preferably, it is 2.5 mass% or more. Furthermore, the total ratio of the (a) compound and the (b) compound in the curable composition of the present invention is usually 50% by mass or more, and preferably 60% by mass or more.
In the curable composition of the present invention, the ratio of the component (A) to the component (B) is not unconditionally determined by various physical properties such as optical characteristics, strength, heat resistance, etc. of the optical material obtained depending on the type of each compound. Is usually 50 to 1 part by weight of component (B) with respect to 50 to 99 parts by weight of component (A), preferably 40 to 2 parts by weight of component (B) with respect to 60 to 98 parts by weight of component (A), More preferably, it is 35 to 5 parts by weight of component (B) with respect to 65 to 95 parts by weight of component (A). When the component (B) is in the range of 50 to 1 part by weight, a cured resin having a high Tg is obtained after curing.

  Furthermore, regarding the ratio of the episulfide group and the thiol group of the component (A) (herein, all thiol compounds to be blended including the component (B)), preferably thiol group / episulfide group = 0.01 to 0 0.5, more preferably thiol group / episulfide group = 0.01 to 0.3, and still more preferably thiol group / episulfide group = 0.01 to 0.2. When the ratio is between 0.01 and 0.5, a cured resin with low yellowness (low coloration) and high heat resistance can be obtained.

In order to cure the curable composition of the present invention, a polymerization catalyst is usually added. A basic compound is preferred as the polymerization catalyst. The polymerization catalyst to be added includes a thermal polymerization catalyst and a photopolymerization catalyst, but is not particularly limited as long as it exhibits polymerization and curing. These polymerization catalysts may be used alone or in combination of two or more.

Examples of the thermal polymerization catalyst include amines, amidines, phosphines, quaternary ammonium salts, quaternary phosphonium salts, and the like. Among these, preferred specific examples are amines such as N, N-dimethyl-2-aminoethanol and triethylamine, tetra-n-butylammonium bromide, triethylbenzylammonium chloride, cetyldimethylbenzylammonium chloride, 1-n-dodecylpyridinium. Examples include quaternary ammonium salts such as chloride, quaternary phosphonium salts such as tetra-n-butylphosphonium bromide, tetraphenylphosphonium bromide.

Preferable photopolymerization catalysts include organoboron compounds. Specifically, tetrabutylammonium = butyltriphenylborate, tetrabutylammonium = butyltri (4-t-butylphenyl) borate, tetrabutylammonium = butyltri (1- Naphthyl) borate, tetrabutylammonium = butyltri (4-methyl-1-naphthyl) borate. Most preferred is tetrabutylammonium butyltri (1-naphthyl) borate, which has a good balance of solubility in episulfide compounds, polymerizability of episulfide compounds, and pot life of the composition. Other preferable photopolymerization catalysts include compounds (photobase generators) that generate bases such as amidines such as DBN (diazabicyclononene) and DBU (diazabicycloundecene).

The addition amount of a polymerization catalyst is 0.001-5 mass parts with respect to a total of 100 mass parts of a component (A) and a component (B) compound, Preferably it is 0.002-5 mass parts, More preferably Is 0.005 to 3 parts by mass.

In the present invention, in the case of heat curing, curing is accelerated when the curable composition is heated to room temperature to 150 ° C. The heating time is not particularly limited because it depends on the curing temperature, but it is preferably 1 minute to 3 days.

In the present invention, in the case of photocuring, a sensitizer may be added in addition to the components (A) and (B) and the polymerization catalyst. It becomes possible to produce | generate a polymerization catalyst more efficiently by mix | blending a sensitizer with a curable composition. As a result, the exposure time can be shortened and the polymerization of the curable composition can be promoted.

Preferred sensitizers are substituted or unsubstituted benzophenones, aromatic ketones such as thioxanthone, anthraquinone or dyes such as oxazine, acridine, phenazine and rhodamine. Particularly preferred is substituted or unsubstituted benzophenone or thioxanthone. Specifically, benzophenone, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis- (diethylamino) benzophenone, 4,4′-bis (ethylmethylamino) benzophenone, 4,4′-diphenyl Benzophenone, 4,4′-diphenoxybenzophenone, 4,4′-bis (p-isopropylphenoxy) benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 2-methoxycarbonylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 4-methoxy-3,3'-methylbenzophenone, isopropylthioxanthone, chlorothioxanthone, 1-chloro-4-propoxythioxanthone, 2- (trifluoromethyl) thioxan And 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 1,3-dimethyl-2- (2-ethylhexyloxy) thioxanthone and the like. These may be used alone or in combination of two or more.

The addition amount of a sensitizer is 0.001-5 mass parts with respect to a total of 100 mass parts of a component (A) and a component (B) compound, Preferably it is 0.002-5 mass parts, and more. Preferably it is 0.005-3 mass parts.

In the curable composition of the present invention, as an optional component, a compound capable of reacting with component (A) and / or component (B) as a resin modifier, a known polymerization inhibitor, a polymerization inhibitor, an antioxidant, blue Of course, it is possible to further improve the practicality of the resulting material by adding various additives such as an ing agent, an ultraviolet absorber, a photosensitizer, and a deodorant as necessary. Further, when the optical material of the present invention is easily peeled off from the mold during polymerization, a known external and / or internal adhesion improver is used, or when it is difficult to peel off from the mold, a known external and / or internal template is improved. It is also effective to apply the agent to a glass or metal mold used for polymerization curing or add it to the optical material composition to improve the adhesion or template of the resulting optical material and mold. Moreover, you may perform filtration, defoaming, etc. as needed.

  The curable composition of the present invention can be cured into a resin by thermal curing or photocuring. In the case of photocuring, it is cured by irradiating with ultraviolet rays or visible light. If the light source used in that case is an apparatus which generate | occur | produces an ultraviolet-ray and visible light, there will be no restriction | limiting in particular. Specific examples include a high pressure mercury lamp, an ultra high pressure mercury lamp, a metal halide lamp, a high power metal halide lamp, and a xenon lamp.

  When the curable composition of the present invention is photocured, polymerization may be inhibited by the influence of oxygen in the air. Therefore, it is preferable to perform exposure in an atmosphere having a low oxygen concentration in order to shorten the exposure time and to sufficiently polymerize the curable composition. Specifically, there is a method of performing exposure by substituting the atmosphere surrounding the curable composition with nitrogen gas or carbon dioxide gas. In this case, the oxygen concentration is preferably 10% or less, and more preferably 5% or less. In addition, a method of performing exposure by coating the surface of the curable composition with a transparent film such as a polypropylene film, and a method of performing exposure by sealingly injecting the curable composition into a transparent mold made of glass or the like. Can be mentioned.

  Curing can be further accelerated | stimulated by irradiating a ultraviolet-ray and visible light to a curable composition, and then heat-processing. The heating temperature and time can be appropriately selected according to the degree of curing required after ultraviolet irradiation, but the heating temperature is preferably room temperature to 150 ° C., and the heating time is preferably 1 minute to 3 days.

  The curable composition of the present invention can be used as an optical adhesive. The resin obtained by curing the curable composition of the present invention is useful as an optical member. Specifically, the optical member is a plastic lens, an optical filter, a microlens array, a prism, a prism sheet, a diffraction grating, an imprint material, a coating agent for an optical element, a resist material, an optical fiber, an information recording base, a mirror, a beam splitter. , Flat panel display substrates, light emitting diode (LED) sealing materials, optical waveguides, and the like.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
The refractive index (nd) and Abbe number (νd) of the cured product were measured using a precision refractometer KPR-2000 (manufactured by Shimadzu Device Manufacturing Co., Ltd.) or NAR-3T (manufactured by Atago Co., Ltd.). The glass transition temperature was determined from the peak temperature of tan δ measured using a viscoelasticity measuring apparatus EXSTER6100DMS manufactured by Seiko Instruments Inc. under the conditions of a temperature range of 30 ° C. to 150 ° C., a temperature increase rate of 2 ° C./min, and a frequency of 10 Hz. Light irradiation was performed using LHPUV365 / 2501 (Iwasaki Electric Co., Ltd.).
The episulfide compound as component (A) was synthesized based on the methods described in JP-A Nos. 9-110979 and 2001-163874. Component (B) 9,9-bis [4- (3-mercaptobutyroyloxyethoxy) phenyl] fluorene and 9- [4- (3-mercaptobutyroyloxyethoxy) phenyl] -9- [4 -(2-Hydroxyethyl) phenyl] -fluorene was synthesized based on the description in JP-A No. 2006-154775.

[Example 1]
Into a 100 ml flask, 2.0 g of 9,9-bis [4- (3-mercaptobutyroyloxyethoxy) phenyl] fluorene (B1) as component (B) was taken and heated to 70 ° C., and then component (A) 18 g of bis (β-epithiopropyl) sulfide (A1) was added and stirred well until uniform. To this, 0.02 g of tetra-n-butylphosphonium bromide (C) was added and stirred until uniform. The curable composition was produced in the above procedure. The obtained curable composition was degassed under reduced pressure and filtered through a 0.45 μm PTFE membrane filter. Next, the composition was poured into a mold in which an O-ring having a thickness of 3.1 ± 0.1 mm and an inner diameter of 39.4 ± 0.37 mm was sandwiched between two opposing 83 mmφ glass molds, Using an oven, the temperature was raised from 30 ° C. for 10 hours, from 30 ° C. to 100 ° C. over 10 hours, and finally polymerized and cured at 100 ° C. for 1 hour. The cured product was allowed to cool to room temperature and released from the mold. A plate-like cured product having a thickness of 2.5 mm made of the resin cured by the above procedure was prepared.
The physical properties of the cured product were as shown in Table 1. The obtained cured product was colorless and transparent.

[Examples 2 to 4, Comparative Examples 1 to 5]
A curable composition and a cured product were prepared in the same manner as in Example 1 except that the types and amounts of component (A) and component (B) were changed to the contents shown in Table 1. The physical properties of the cured product were as shown in Tables 1 and 2. All of the obtained cured products were colorless and transparent. The cured product obtained in Comparative Example 3 had a glass transition temperature of 50 ° C. or lower.

[Example 5]
Into a 100 ml flask, 2.0 g of 9,9-bis [4- (3-mercaptobutyroyloxyethoxy) phenyl] fluorene (B1) as component (B) was taken and heated to 70 ° C., and then component (A) 18 g of bis (β-epithiopropyl) sulfide (A1) was added and stirred well until uniform. To this, 0.2 g of 1-hydroxy-cyclohexyl phenyl ketone (D) as a photocuring agent and 0.2 g of 4-benzoyl-4′-methyldiphenyl sulfide (E) as a sensitizer were added and stirred until uniform. . The curable composition was produced in the above procedure.

The curable composition was sandwiched between two release-treated glass plates and irradiated with 365 nm LED (20 mW / cm ² ) light for 3 minutes. A cured film having a thickness of 0.25 mm was produced by the above procedure.
The physical properties of the cured film were as shown in Table 1. The obtained cured film was colorless and transparent.

[Comparative Example 6]
A curable composition and a cured film were prepared in the same manner as in Example 5 except that the types and amounts of component (A) and component (B) were changed to those shown in Table 1. The physical properties of the cured film were as shown in Table 2. The obtained cured film was colorless and transparent.

Ａ１：ビス（β−エピチオプロピル）スルフィド（式（２）の化合物）
Ｂ１：９，９−ビス［４−（３−メルカプトブチロイロキシエトキシ）フェニル］フルオレン（式（７）の化合物）
Ｂ２：９−［４−（３−メルカプトブチロイロキシエトキシ）フェニル］−９−［４−（２−ヒドロキシエチル）フェニル］−フルオレン（式（１０）の化合物）
Ｃ：テトラ−ｎ−ブチルホスホニウムブロマイド
Ｄ：１−ヒドロキシ−シクロヘキシルフェニルケトン
Ｅ：４−ベンゾイル−４’−メチルジフェニルスルフィド

A1: Bis (β-epithiopropyl) sulfide (compound of formula (2))
B1: 9,9-bis [4- (3-mercaptobutyroyloxyethoxy) phenyl] fluorene (compound of formula (7))
B2: 9- [4- (3-Mercaptobutyroyloxyethoxy) phenyl] -9- [4- (2-hydroxyethyl) phenyl] -fluorene (compound of formula (10))
C: Tetra-n-butylphosphonium bromide D: 1-hydroxy-cyclohexyl phenyl ketone E: 4-benzoyl-4'-methyldiphenyl sulfide

Ｂ３：ビス（２−メルカプトエチル）スルフィド
Ｂ４：ペンタエリスリトールテトラキス（３−メルカプトプロピオネート）

B3: Bis (2-mercaptoethyl) sulfide B4: Pentaerythritol tetrakis (3-mercaptopropionate)

By curing a curable composition of B1 or B1 / B2 mixture as component (B) and A1 as component (A), the refractive index is 1.68, the Abbe number is 31 or more, and the optical material is low. It was possible to obtain a cured resin with improved heat resistance such that Tg was 106 ° C. or higher while sufficiently having yellowness and high transparency. On the other hand, when B3 and B4 were used as the component (B), the Tg was 105 ° C. or lower even when the refractive index was 1.68 or higher when compared at the same composition ratio.
In particular, the difference in Tg when compared at the same composition ratio is as large as 35 ° C. or more, and the heat resistance by adding a compound having at least one thiol group to the aromatic skeleton represented by the formula (4) described in the present application. The effect of improving the property was very large, and a high refractive index cured resin having improved heat resistance was obtained.

Claims (7)

A curable composition containing an episulfide compound represented by the formula (1) and a thiol compound represented by the formula ( 5 ).

(In Formula (1), m1 represents an integer of 0 to 4, and m2 represents an integer of 0 to 2. )

(In the formula (5), Z represents an alkyl group having 1 to 3 carbon atoms, a halogen group, a halogenated alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, an amino group, a nitro group, or a hydroformyl group. Or a plurality of Z may be different, n1 may be different, an integer of 1 to 4, n2 may be different, an integer of 0 to 4, and n3 may be different. It often represents an integer of 0 to 4. However, it has a relationship of n1 + n3 ≦ 5, R ₁ and R ₂ are the same or different and each represents an alkylene group having 1 to 4 carbon atoms, and n4 is the same or different and represents 0 to Represents an integer of 4. n5 is the same or different and represents an integer of 0 to 2. However, at least one of n4 is an integer of 1 or more.   Furthermore, the curable composition of Claim 1 containing a basic compound.   The curable composition according to claim 2, wherein the basic compound is a photobase generator.   Resin which hardens the curable composition in any one of Claims 1-3.   A method for producing a resin, comprising curing the curable composition according to claim 1.   An optical member made of the resin according to claim 4. An optical adhesive using the curable composition according to claim 1.