WO2012147708A1

WO2012147708A1 - Curable composition and adhesive for optics

Info

Publication number: WO2012147708A1
Application number: PCT/JP2012/060899
Authority: WO
Inventors: 淳也早川; 岡崎　仁; 竹内　基晴
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2011-04-28
Filing date: 2012-04-24
Publication date: 2012-11-01
Also published as: CN103562273A; TWI521035B; TW201311847A; CN103562273B

Abstract

Provided are a curable composition and the like that have a high refractive index and possess the properties required of an adhesive for optics in that they are photocurable, low-shrinking, and colorless and transparent and have a workable viscosity. The invention provides a curable composition comprising a polythiol oligomer obtained by reacting a polythiol and sulfur (component A) and a polyene compound (component B), and a curable composition comprising a polythiol oligomer obtained by reacting a polythiol and sulfur (component A), an episulfide compound (component C) and a photobase generator (component D).

Description

Curable composition and optical adhesive

The present invention relates to a curable composition suitable as an optical adhesive used for producing a composite optical element.

A photocurable composition mainly composed of an acrylate compound or the like is widely used as an adhesive for producing an optical element. Adhesives, photocurability, mechanical strength, durability, and optical properties are basic performances for adhesives, but in recent years, the refractive index has become an important performance as optical elements become more sophisticated. . In particular, increasing the refractive index of the adhesive is highly desired because the degree of freedom in optical design is expanded. Application examples in which an adhesive having a high refractive index is used, for example, as an example of a composite optical element, an achromatic lens (achromat lens) formed by bonding two lenses, and a composite of glass and resin Examples include a prism having a complicated shape such as a hybrid aspherical lens and a dichroic prism. Adhesives used for these applications are required not only to have a high refractive index, but also to have performance such as adhesion, photocurability, colorless transparency, heat resistance, and viscosity suitable for work.

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 1.70. Since the episulfide compound has a low viscosity and can be easily injected into a mold, it is suitable for producing a molded article such as a spectacle lens. However, assuming use as an adhesive, if the viscosity is too low, the adhesive may sag or flow, and the adherend may be displaced during pasting, which causes problems in workability. Moreover, since the episulfide compound generally has a large shrinkage due to curing, when used as an adhesive, it causes a decrease in adhesion.

Further, as a polyfunctional (meth) acrylate compound having a high refractive index, 9,9-bis (4- (2-acryloxyethoxy) phenyl) fluorene (hereinafter referred to as A-BPEF) (refractive index of cured product 1 .62), 4,4′-bis (methacryloylthio) diphenyl sulfide (hereinafter referred to as MPSMA) (refractive index of cured product 1.69) and the like. However, since these compounds are solid at room temperature, it is difficult to use them alone.
In general, a polyfunctional (meth) acrylate compound has a large shrinkage due to curing, and causes a decrease in adhesion when used as an adhesive.

On the other hand, an ene / thiol composition combining an ethylenically unsaturated compound such as a (meth) acrylate compound and a thiol compound has a high refractive index cured product because the thiol compound contains a sulfur atom having a high atomic refraction. It is known that However, addition polymerization of thiol groups and ethylenically unsaturated bond groups has fewer crosslinking points than chain polymerization, and the resulting sulfide bonds tend to give a soft cured product. There are issues that tend to soften. In order to obtain sufficient heat resistance, it is necessary to select a polyfunctional ethylenically unsaturated compound and a thiol compound.

Patent Document 5 describes an ene-thiol composition composed of a bifunctional thiol compound containing a 1,4-dithiane ring and triallyl isocyanurate or triallyl cyanurate. However, the refractive index of the cured product is not particularly described. Moreover, since the bifunctional thiol compound is used, the cured product is easily softened at a high temperature (see Comparative Example).
Patent Document 6 describes an ene-thiol composition composed of A-BPEF, an ethylenically unsaturated compound, and a thiol compound. According to the examples, the refractive index of the cured product is at most in the range of 1.58 to 1.61.
Patent Document 7 describes an ene / thiol composition composed of MPSMA, a vinyl monomer, and polythiol. According to the example, the refractive index of the cured product is 1.649 at the maximum. However, MPSMA is easily yellow-colored and has a limit in the amount of dissolution in the composition because it is solid.
Patent Document 8 describes a resin composition composed of a resin component having a fluorene ring and a sulfur-containing compound having a diphenyl sulfide skeleton such as MPSMA, and a resin having a refractive index of 1.724. Illustrated. However, the resin composition in the present invention is substantially a thermoplastic resin obtained by kneading a polyester having a fluorene ring and a sulfur-containing compound and is not a curable composition, and of course, photocurability cannot be imparted.

Japanese Patent Laid-Open No. 9-71580 Japanese Patent Laid-Open No. 9-110979 Japanese Patent Laid-Open No. 9-255781 JP 2001-163874 A JP 2000-154251 A JP 2010-254732 A Japanese Patent Laid-Open No. 03-021638 JP 2005-187661 A

Accordingly, an object of the present invention is to provide a curable composition having a high refractive index and also having performances required as an optical adhesive such as photocurability, low shrinkage, colorless transparency, and viscosity suitable for work. Is to provide.

As a result of intensive studies to solve the above problems, the present inventors have found that a curable composition containing a polythiol oligomer (component A) obtained by reacting polythiol and sulfur and a polyene compound (component B), The inventors have found that it is possible to further increase the refractive index and also have the necessary performance as an optical adhesive, and have reached the present invention.
Further, the present inventors have disclosed that a curable composition containing a polythiol oligomer (component A) obtained by reacting polythiol and sulfur, an episulfide compound (component C), and a photobase generator (component D) is an adhesive. It has been found that it is suitable as an optical adhesive because it has a viscosity suitable for workability and has a small shrinkage due to curing. Furthermore, it is preferable to use a basic catalyst when reacting polythiol and sulfur. However, when hindered amine is used as this catalyst, a curable composition having excellent storage stability (the reaction of episulfide is sufficiently slow) is obtained. I found out that Based on the above findings, the present invention has been achieved.

According to the present invention, there is provided a curable composition having a high refractive index and also having performance as an optical adhesive such as photocurability, low shrinkage, colorless transparency and viscosity suitable for work. be able to.

The first curable composition of the present invention comprises a polythiol oligomer (A component) obtained by reacting polythiol and sulfur and a polyene compound (B component).
First, the manufacturing method of a polythiol oligomer (A component) is demonstrated.

The polythiol used as the raw material of the polythiol oligomer is a compound having two or more thiol groups in one molecule, and may be any of linear, branched, and cyclic. In particular, when pursuing a viscosity suitable for increasing the refractive index and workability of the curable composition, compounds represented by the following general formulas (1) to (3) are preferable.

(Wherein p1 and p2 each independently represents an integer of 0 to 1, and X ₁ to X ₈ each independently represents a hydrogen atom or a methylthiol group.)

(In the formula, q represents an integer of 0 to 3, and R ¹ represents a simple bond or an alkylene group having 1 to 3 carbon atoms.)

(In the formula, r represents an integer of 0 to 3, and R ² represents an alkylene group having 1 to 3 carbon atoms.)

Examples of the compound represented by the general formula (1) include 1,5-dimercapto-3-thiapentane, 2-mercaptomethyl-1,5-dimercapto-3-thiapentane, 2,4-bis (mercaptomethyl) -1 , 5-dimercapto-3-thiapentane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-bis (mercaptomethyl) -1,11-dimercapto-3,6,9-trithia Undecane, 4,7-bis (mercaptomethyl) -1,11-dimercapto-3,6,9-trithiaundecane, 5,7-bis (mercaptomethyl) -1,11-dimercapto-3,6,9- Examples of the compound represented by the general formula (2) include 2,5-dimercapto-1,4-dithiane and 2,5-dithiane. Rukaputomechiru dithiane, 2,5-mercaptoethyl-1,4-dithiane, and examples of the compound represented by formula (3), xylylenedithiol and the like. Examples of the polythiol compound other than the compounds represented by the general formulas (1) to (3) include ethylene glycol bis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3 -Mercaptopropionate), benzenedithiol, tolylenedithiol and the like.

Regarding sulfur as a raw material for polythiol oligomer, sulfur forms many allotropes, and generally well-known cyclic S8 sulfur is preferable. Sulfur may be in any form, for example, crystalline, colloidal, powder, or sulfur.

According to Journal of Organic Chemistry, Vol. 32, pages 3833 to 3836 (1967), for example, when the product is a dimer, the reaction of polythiol is mainly represented by the following reaction formulas (6) and (7):

(In the formula, R represents an organic group, and n represents an integer of 1 or more.)
Proceed according to. The amount of sulfur used is preferably in the range of 0.2 to 0.95 moles of sulfur atoms, more preferably in the range of 0.2 to 0.5 moles per mole of thiol group. If it is less than 0.2 mol, the conversion rate of polythiol is too low to be practical, and if it exceeds 0.95 mol, a polythiol oligomer having an excessive molecular weight which is not preferable as a raw material for optical materials is generated and unreacted sulfur remains. It is easy to do and is not preferable.

The reaction between polythiol and sulfur proceeds by heating in the presence or absence of a basic catalyst, but a method using a basic catalyst is preferred. Examples of the basic catalyst include amines, ammonium salts, phosphines, and phosphonium salts. The amount of the basic catalyst used is preferably in the range of 0.005 to 5 mol, more preferably in the range of 0.05 to 0.5 mol, with respect to 100 mol of the thiol group contained in the raw polythiol.

Each raw material can be added by adding a catalyst to the polythiol and sulfur mixed solution, adding sulfur to the polythiol and catalyst mixed solution, or adding the polythiol and sulfur mixed solution to the polythiol and sulfur mixed solution. May be. In order to allow the reaction to proceed gently, the catalyst and sulfur may be added in several portions.

The reaction between polythiol and sulfur may be performed in the presence of a polyene compound (component B). Since the reaction between polythiol and sulfur is accompanied by the generation of hydrogen sulfide, the reaction is preferably performed under exhaust or reduced pressure. You may use a solvent as needed. When using a solvent, a post-process for distilling off the solvent is required. The reaction temperature is not particularly limited, but it is preferably in the range of 0 to 100 ° C. The temperature may be gradually raised while checking the progress of the reaction. The reaction time depends on various conditions such as the type of raw material, the ratio of polythiol and sulfur, and the reaction temperature, and thus cannot be defined unconditionally, but the reaction is continued until no unreacted sulfur remains.

Next, the 1st curable composition of this invention is demonstrated.
The 1st curable composition of this invention is comprised including the polythiol oligomer (A component) and polyene compound (B component) which were mentioned above.

The polyene compound (component B) is a compound having two or more ethylenically unsaturated bond groups in one molecule, and examples of the ethylenically unsaturated bond group include acryloyl group, methacryloyl group, vinyl group, and allyl group. Can be mentioned. In particular, when pursuing a high refractive index of the curable composition, a compound having an aromatic ring or a heterocyclic ring in the molecule is preferable. Examples of such a compound include triallyl isocyanurate, triallyl cyanurate, diallyl phthalate. , Diallyl isophthalate, diallyl terephthalate, triallyl trimellitic acid, tetraallyl pyromellitic acid, a compound represented by general formula (4), a compound represented by general formula (5), and the like.

(In the formula, X represents a sulfur atom or a sulfonyl group, and Z represents a (meth) acryloyl group, a vinyl group, or an allyl group.)

(In the formula, m and n represent an integer in which the sum of m and n satisfies 0 to 4, R ³ represents an alkylene group having 1 to 5 carbon atoms, R ⁴ represents a hydrogen atom or a methyl group, R ⁵ represents a hydrogen atom or a methyl group.)
Examples of the compound represented by the general formula (4) include 4,4′-bis (methacryloylthio) diphenyl sulfide, 4,4′-bis (methacryloylthio) diphenyl sulfone, and the like. Examples of the compound represented include 9,9-bis (4- (2-acryloxyethoxy) phenyl) fluorene.

The content of the polythiol oligomer in the first curable composition is preferably in the range of 10 to 80 parts by weight, more preferably in the range of 20 to 70 parts by weight with respect to 100 parts by weight of the curable composition. When the content of the polythiol oligomer is less than 10 parts by weight, the effect of increasing the viscosity or reducing the shrinkage is reduced, and when it exceeds 80 parts by weight, the toughness of the cured product is lowered, which is not preferable.

If necessary, a polymerization inhibitor, an antioxidant, a light stabilizer (HALS), an ultraviolet absorber, a silane coupling agent, a release agent, a pigment, a dye, and the like may be added to the curable composition of the present invention. Is possible.

The curable composition of the present invention is cured by irradiation with an actinic ray such as ultraviolet light or visible light in the presence of a radical photopolymerization initiator. The radical photopolymerization initiator is not particularly limited as long as it generates an active free radical by photolysis. Specific examples of such compounds include 2,2-methoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropane-1- ON, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, Examples thereof include bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, and the like. The radical photopolymerization initiators may be used alone or in combination of two or more. The content is not particularly limited, but is preferably in the range of 0.1 to 10 parts by weight, more preferably in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the curable composition.

Assuming that the curable composition is used as an adhesive with respect to the viscosity of the curable composition, if the viscosity is too low, the adhesive may sag or flow, or the adherend may be displaced during bonding, which is not preferable. On the other hand, if the viscosity is too high, it is not preferable because it becomes difficult to discharge or apply the adhesive, or the air bubbles are bitten at the time of bonding. The viscosity suitable for workability in the first curable composition cannot be defined unconditionally because it depends on the use form of the adhesive such as the coating method and the laminating method, but is preferably 500 to 20,000 mPa · s. The range is more preferably 1,000 to 10,000 mPa · s.

The second curable composition of the present invention comprises a polythiol oligomer (A component) obtained by reacting polythiol and sulfur, an episulfide compound (C component), and a photobase generator (D component). .

First, the method for producing the polythiol oligomer (component A) in the second curable composition is generally as described for the first curable composition. Hereinafter, the manufacturing method of the polythiol oligomer (A component) in the second curable composition will be described focusing on the difference from the manufacturing method of the polythiol oligomer (A component) in the first curable composition.

Also in the second curable composition, the reaction between polythiol and sulfur proceeds by heating in the presence or absence of a basic catalyst, but a method using a basic catalyst is preferred. In particular, a hindered amine is preferable as the base catalyst. The hindered amine refers to an amine having a substituent on both sides of the amino group. Hindered amines are weak in activity as polymerization catalysts for episulfide compounds due to steric hindrance of substituents. As a result, the curable composition combining the polythiol oligomer and the episulfide compound is sufficiently stable (the polymerization of the episulfide compound is sufficiently slow), and can be stored for a long period of time. As the hindered amine, a compound having a 2,2,6,6-tetramethylpiperidine skeleton is preferable. Specifically, 2,2,6,6-tetramethylpiperidine, 1,2,2,6,6-penta Methylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-1,2,2,6,6-pentamethylpiperidine, acrylic acid 2,2,6,6-tetramethyl- 4-piperidyl, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl acrylate, 1,2,2,6,6 methacrylate -Pentamethyl-4-piperidyl, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl sebacate) Le) and the like. The amount of the basic catalyst used is preferably in the range of 0.005 to 5 mol, more preferably in the range of 0.05 to 0.5 mol, with respect to 100 mol of the thiol group contained in the raw polythiol.

The reaction between polythiol and sulfur may be performed in the presence of an episulfide compound (component C). However, if an appropriate basic catalyst is not selected, the episulfide compound may be polymerized to cause gelation. Therefore, when a basic catalyst is used, hindered amine is preferable for the reason described above.

Next, the 2nd curable composition of this invention is demonstrated.
The 2nd curable composition of this invention is comprised including the polythiol oligomer (A component) mentioned above, an episulfide compound (C component), and a photobase generator (D component).
An episulfide compound (component C) is a compound having one or more episulfide groups in one molecule. In particular, when pursuing a high refractive index of the curable composition, the following general formula (8)

Wherein m is an integer from 0 to 6, n is an integer from 0 to 4, R ³ and R ⁴ are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ⁵ , R 4 ⁶ is each independently an alkylene group having 1 to 10 carbon atoms.)
The compound represented by these is preferable. Examples of the episulfide compound represented by the general formula (8) include bis (2,3-epithiopropyl) sulfide.

Although the episulfide compound represented by the general formula (8) has a large shrinkage due to curing, the shrinkage accompanying the curing can be suppressed by copolymerizing with the polythiol oligomer. The episulfide compound represented by the general formula (8) generally has a low viscosity, but is adjusted to a viscosity excellent in workability by mixing with the polythiol oligomer.

Even in the second curable composition, regarding the viscosity of the curable composition, assuming that it is used as an adhesive, if the viscosity is too low, the adhesive may sag or flow, or the substrate may be displaced during pasting. It is not preferable. On the other hand, if the viscosity is too high, it is not preferable because it becomes difficult to discharge or apply the adhesive, or bubbles are bitten during the bonding. The viscosity suitable for workability in the second curable composition cannot be unconditionally defined because it depends on the use form of the adhesive such as the coating method and the laminating method, but is preferably in the range of 100 to 50,000 mPa · s. More preferably, it is in the range of 500 to 10,000 mPa · s.

The content of the polythiol oligomer in the second curable composition is preferably in the range of 10 to 70 parts by weight, more preferably in the range of 20 to 50 parts by weight with respect to 100 parts by weight of the curable composition. If the content of the polythiol oligomer is less than 10 parts by weight, the effect of increasing the viscosity or reducing the shrinkage is reduced, and if it exceeds 70 parts by weight, the toughness of the cured product is lowered, which is not preferable.

The photobase generator (component D) is a compound that generates a base by photolysis with actinic rays. In particular, since the polymerization of episulfide compounds is promoted by amidine such as DBN (diazabicyclononene) and DBU (diazabicycloundecene), photobase generators that generate these bases are preferred. Specifically, the amidinium ketone (the left side of the following formula (9)) forming the tetraarylborate salt described in JP-T-2001-513765 and the aryl described in JP-T-2005-511536 1,3-diamine substituted with an alkyl group (left side of the following formula (10)) and the like. These may be used alone or in combination of two or more. The addition amount of the photobase generator is preferably in the range of 0.01 to 10 parts by weight, more preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the curable composition.

In addition to the photobase generator, a photosensitizer may be included. By adding the photosensitizer, the photodecomposition of the photobase generator is accelerated, and the curing time of the photocurable composition can be shortened. Specific examples of the photosensitizer include benzophenones, thioxanthones, anthraquinones, camphorquinones, benzyls, Michler ketones, and anthracenes. These may be used alone or in combination of two or more. The addition amount of the photosensitizer is preferably from 0.01 to 10 parts by weight, more preferably from 0.1 to 5 parts by weight, based on 100 parts by weight of the curable composition.

If necessary, a polymerization inhibitor, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a silane coupling agent, a release agent, a pigment, a dye, and the like can be added to the curable composition. . Moreover, you may perform filtration, defoaming, etc. as needed.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, the cure shrinkage rate in an Example was computed from the refractive index before and behind hardening according to the following formula.
X = (1−d1 / d2) × 100 [%]
R = (n ² −1) / (n ² +2) × M / d
Since R / M is constant before and after curing,
X = [1-{(n1 ² −1) / (n1 ² +2)} / {(n2 ² −1) / (n2 ² +2)}] × 100 [%]
(Where X is the curing shrinkage ratio, d is the specific gravity, d1 is the specific gravity before curing, d2 is the specific gravity after curing, R is the molecular refraction, n is the refractive index, n1 is the refractive index before curing, and n2 is the after curing The refractive index of M and M represents the molecular weight.)
The viscosity of the curable composition was measured at a temperature of 25 ° C. using a cone / plate viscometer DV-II + (manufactured by Brookfield). The refractive indexes of the curable composition and the cured product (cured film) were measured using an Abbe refractometer NAR-3T (manufactured by Atago Co., Ltd.). The transmittance of the cured product was measured using a spectrophotometer U-3500 (manufactured by Hitachi High-Tech) at a thickness of 0.25 mm and a wavelength of 400 nm.

First, examples of the first curable composition will be described below.
Example 1
In a 300 ml flask, 65 g of 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane and 0.05 g of dicyclohexylmethylamine were taken and stirred well. 4.7 g of sulfur powder was slowly added dropwise in several portions at room temperature. When sulfur powder was added, the solution turned yellow and gas was generated. After the generation of gas became slow, the temperature was raised to 60 ° C. while flowing nitrogen gas through the liquid surface, and stirring was continued for 3 hours. As the reaction progressed, gas generation almost disappeared and the solution became colorless and transparent. The polythiol oligomer was produced by the above procedure.
After cooling the polythiol oligomer to room temperature, 35 g of triallyl isocyanurate was added and stirred until uniform. The 1st curable composition was produced in the above procedure.

3 parts by weight of 1-hydroxy-cyclohexyl phenyl ketone was added to 100 parts by weight of the first curable composition, and the mixture was stirred until uniform and degassed under reduced pressure. This was sandwiched between two release-treated glass plates, irradiated with light from a metal halide lamp (120 W / cm) for 3 minutes from a distance of 30 cm, and then the cured film was peeled off from the glass plate. A cured film having a thickness of 0.25 mm was produced by the above procedure. The physical properties of the curable composition and the cured film (cured product) were as shown in Table 1.

Examples 2-5
A first curable composition and a cured product were prepared in the same manner as in Example 1 except that the types and amounts of polythiol, sulfur, and polyene compound were changed to the contents shown in Table 1. The physical properties of the first curable composition and the cured product were as shown in Table 1.

Comparative Example 1
In a 300 ml flask, 55 g of 2,5-dimercaptomethyl-1,4-dithiane and 45 g of triallyl isocyanurate were taken and stirred until uniform. The curable composition was produced in the above procedure.
A cured film was produced in the same manner as in Example 1. The physical properties of the curable composition and the cured product were as shown in Table 2. In addition, the value which performance is inferior compared with an Example was underlined.

Comparative Examples 2-4
A curable composition and a cured product were prepared in the same manner as in Comparative Example 1 except that the types and amounts of the thiol compound and ethylenically unsaturated compound were changed to those shown in Table 2. The physical properties of the curable composition and the cured product were as shown in Table 2. In addition, the value which performance is inferior compared with an Example was underlined.

[Supplement under rule 26 22.06.2012]

[Supplement under rule 26 22.06.2012]

Explanation of Abbreviations in Table (a-1) 4-Mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane (a-2) 2,5-dimercaptomethyl-1,4-dithiane (a-3) m -Xylylenedithiol (a-4) 1,5-dimercapto-3-thiapentane (b-1) triallyl isocyanurate (b-2) 4,4'-bis (methacryloylthio) diphenyl sulfide (b-3) trimellit Acid triallyl (b-4) 2,2-bis (4- (acryloxydiethoxy) phenyl) propane

Next, examples of the second curable composition will be described below.
Example 6
In a 300 ml flask, 40 g of 2,5-dimercaptomethyl-1,4-dithiane and 0.05 g of tributylamine were taken and stirred well. 6.0 g of sulfur powder was slowly added dropwise in several portions at room temperature. When sulfur powder was added, the solution turned yellow and gas was generated. After the generation of gas became slow, the temperature was raised to 60 ° C. while flowing nitrogen gas through the liquid surface, and stirring was continued for 3 hours. As the reaction progressed, gas generation almost disappeared and the solution became colorless and transparent. The polythiol oligomer was produced by the above procedure.

To this polythiol oligomer (component A), bis (2,3-epithiopropyl) sulfide 60 g (component C), the following structural formula (11)

0.2 g (component D) represented by the formula (1) and 1 g of 4-benzoyl-4′-methyldiphenyl sulfide as a sensitizer were added and stirred until uniform. The 2nd curable composition was produced in the above procedure. The viscosity of the curable composition was 900 mPa · s (20 ° C.). Moreover, when it preserve | saved for one week at 5 degreeC, the curable composition was gelatinized.

The curable composition was sandwiched between two release-treated glass plates, irradiated with light from a metal halide lamp (120 W / cm) for 3 minutes from a distance of 30 cm, and then the cured film was peeled from the glass plate. A cured film having a thickness of 0.25 mm was produced by the above procedure.
The physical properties of the second curable composition and the cured film were as shown in Table 3.

Example 7
In a 300 ml flask, 40 g of 2,5-dimercaptomethyl-1,4-dithiane, 60 g of bis (2,3-epithiopropyl) sulfide, 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate .1 g was taken and stirred well. 6.0 g of sulfur powder was slowly added dropwise in several portions at room temperature. When sulfur powder was added, the solution turned yellow and gas was generated. After the generation of gas became slow, the temperature was raised to 60 ° C. while flowing nitrogen gas through the liquid surface, and stirring was continued for 3 hours. As the reaction progressed, gas generation almost disappeared and the solution became colorless and transparent. After cooling to room temperature, 0.2 g (component D) of the photobase generator represented by the above structural formula (11) and 1 g of 4-benzoyl-4′-methyldiphenyl sulfide as a sensitizer were added uniformly. Stir until. The curable composition was produced in the above procedure. The viscosity of the curable composition was 1,000 mPa · s (20 ° C.). The viscosity after storage at 5 ° C. for 1 week was 1,100 mPa · s (20 ° C.).

A cured product was prepared in the same manner as in Example 6. The physical properties of the second curable composition and the cured film were as shown in Table 3.

Examples 8-14
The 2nd curable composition and hardened | cured material were produced like Example 7 except having changed the kind and preparation amount of polythiol, sulfur, and an episulfide compound into the content shown in Table 3 and Table 4. FIG. The physical properties of the second curable composition and the cured product were as shown in Tables 3 and 4.

Comparative Example 5
100 g of bis (2,3-epithiopropyl) sulfide, 0.2 g of photobase generator (component D) represented by the structural formula (9), and 4-benzoyl-4′-methyldiphenyl sulfide as a sensitizer 1 g was added and stirred until uniform. The curable composition was produced in the above procedure.
A cured product was produced in the same manner as in Example 6. The physical properties of the curable composition and the cured product were as shown in Table 5. In addition, physical properties that are inferior to those of the examples are underlined.

Comparative Example 6
2,5-dimercaptomethyl-1,4-dithiane 20 g, bis (2,3-epithiopropyl) sulfide 80 g, photobase generator 0.2 g (component D) represented by the structural formula (9), Then, 1 g of 4-benzoyl-4′-methyldiphenyl sulfide was added as a sensitizer and stirred until uniform. The curable composition was produced in the above procedure.
A cured product was produced in the same manner as in Example 6. The physical properties of the curable composition and the cured product were as shown in Table 5. In addition, physical properties that are inferior to those of the examples are underlined.

[Supplement under rule 26 22.06.2012]

[Supplement under rule 26 22.06.2012]

[Supplement under rule 26 22.06.2012]

Explanation of Abbreviations in Table (a′-1) 2,5-Dimercaptomethyl-1,4-dithiane (a′-2) m-xylylenedithiol (a′-3) 1,5-dimercapto-3-thiapentane (B′-1) tributylamine (b′-2) 1,2,2,6,6-pentamethyl-4-piperidyl (c-1) bis (2,3-epithiopropyl) sulfide methacrylate

Claims

Polythiol oligomer (A component) and polyene compound (B component) obtained by reacting polythiol and sulfur, or
A curable composition containing a polythiol oligomer (component A) obtained by reacting polythiol and sulfur, an episulfide compound (component C), and a photobase generator (component D).
The curable composition according to claim 1, wherein the polythiol is at least one selected from the group consisting of the following general formula (1), the following general formula (2), and the following general formula (3).

(Wherein p1 and p2 each independently represents an integer of 0 to 1, and X 1 to X 8 each independently represents a hydrogen atom or a methylthiol group.)

(In the formula, q represents an integer of 0 to 3, and R 1 represents a simple bond or an alkylene group having 1 to 3 carbon atoms.)

(In the formula, r represents an integer of 0 to 3, and R 2 represents an alkylene group having 1 to 3 carbon atoms.)
The curable composition according to claim 1 or 2, wherein the ratio of polythiol and sulfur in the reaction of polythiol and sulfur is in the range of 0.2 to 0.95 moles of sulfur atom per mole of thiol group. object.
Polyene compound (component B) is triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl isophthalate, diallyl terephthalate, triallyl trimellitic acid, tetraallyl pyromellitic acid, compound represented by general formula (4), general formula The curable composition according to any one of claims 1 to 3, wherein the curable composition is at least one selected from the group consisting of compounds represented by (5).

(In the formula, X represents a sulfur atom or a sulfonyl group, and Z represents a (meth) acryloyl group, a vinyl group, or an allyl group.)

(In the formula, m and n represent an integer in which the sum of m and n satisfies 0 to 4, R 3 represents an alkylene group having 1 to 5 carbon atoms, R 4 represents a hydrogen atom or a methyl group, R 5 represents a hydrogen atom or a methyl group.)
The curable composition according to any one of claims 1 to 4, wherein a hindered amine is used as a reaction catalyst when the polythiol and sulfur are reacted.
6. The curable composition according to claim 5, wherein the hindered amine is a compound having a 2,2,6,6-tetramethylpiperidine skeleton.
The curable composition according to any one of claims 1 to 6, wherein the episulfide compound (component C) is a compound represented by the following general formula (8).

Wherein m is an integer from 0 to 6, n is an integer from 0 to 4, R 3 and R 4 are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R 5 , R 4 6 is each independently an alkylene group having 1 to 10 carbon atoms.)
The curable composition according to claim 7, wherein the compound represented by the general formula (8) is bis (2,3-epithiopropyl) sulfide.
An optical adhesive containing the curable composition according to any one of claims 1 to 8.