JP6230419B2 - Curable composition and optical adhesive - Google Patents

Description

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

  Photocurable compositions such as acrylate compounds are widely used as adhesives when producing optical elements. 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. Examples of applications in which an adhesive having a high refractive index is used include an achromatic lens (achromatic lens) composed of two lenses bonded together, a hybrid aspherical lens composed of a composite of glass and resin, and dichroic Examples include prisms having complicated shapes such as prisms. Adhesives used for these applications naturally require not only a high refractive index but also performance such as adhesion, photocurability, colorless transparency, 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.

JP-A-9-71580 Japanese Patent Laid-Open No. 9-110979 Japanese Patent Laid-Open No. 9-255781 JP 2001-163874 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 polythiourethane oligomer (component A), an episulfide compound (component B), and a photobase generator (C) obtained by reacting polythiol and polyisocyanate. It has been found that the curable composition containing the component) is suitable as an optical adhesive because it has a viscosity suitable for workability as an adhesive and has little shrinkage due to curing. 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 curable composition of the present invention comprises a polythiourethane oligomer (A component) obtained by reacting polythiol and polyisocyanate, an episulfide compound (B component), and a photobase generator (C component). .

（式中、ｐ１およびｐ２はそれぞれ独立に０〜１の整数を表し、Ｘ_１〜Ｘ_８はそれぞれ独立に水素原子またはメチルチオール基を表す。）

（式中、ｑは０〜３の整数を表し、Ｒ^１は単なる結合または炭素数１〜３のアルキレン基を表す。）

（式中、ｒは０〜３の整数を表し、Ｒ^２は炭素数１〜３のアルキレン基を表す。）First, the manufacturing method of a polythiourethane oligomer (component A) will be described.
The polythiol used as a raw material for the polythiourethane 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.

(In the formula, p1 and p2 each independently represent an integer of 0 to ₁ , and X _{1 to} X ₈ each independently represent 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, and 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-dimene. Kaputomechiru dithiane, 2,5-mercaptoethyl-1,4-dithiane, and examples of the compound represented by formula (3), xylylenedithiol and the like. Examples of polythiol compounds other than the compounds represented by the general formulas (1) to (3) include ethylene glycol bis (3-mercaptopropionate), trimethiolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3 -Mercaptopropionate), benzenedithiol, tolylenedithiol and the like.

  The polyisocyanate used as a raw material for the polythiourethane oligomer is a compound having two or more isocyanate groups in one molecule, and may be any of linear, branched, and cyclic. Examples of such polyisocyanates include m-xylylene diisocyanate, 1,3-bis (2-isocyanato-2-propyl) benzene, tolylene diisocyanate, diphenylmethane-4,4′-diisocyanate, 1,3-bis. (2-isocyanato-2-propyl) cyclohexane, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, tris (6-isocyanatohexyl) isocyanurate and the like. These may be used alone or in combination of two or more. In particular, when high refractive index and low yellowness of the curable composition are pursued, preferred polyisocyanates are m-xylylene diisocyanate, 1,3-bis (2-isocyanato-2-propyl) benzene, 1,3. -Bis (2-isocyanato-2-propyl) cyclohexane, isophorone diisocyanate.

（式中、ＲおよびＲ’は有機基を表し、ａおよびｂは１以上の整数を表す。）
に従って進行する。チオール基とイソシアネート基が１対１モルで反応するため、チオール基とイソシアネート基のモル比が１に近いほど分子量が大きなポリチオウレタンオリゴマーが生成する。ポリチオールとポリイソシアネートの混合比は、チオール基１モルに対してイソシアネート基が０．２〜０．９５モルの範囲が好ましく、０．４〜０．９５モルの範囲がより好ましい。０．２モル未満ではチオール基の転化率が低すぎて実用的でないし、０．９５モルを超えると未反応のイソシアネート基が残存して好ましくない。The reaction of polythiol and polyisocyanate is, for example, when the product is a dimer, the following reaction formula

(In the formula, R and R ′ represent an organic group, and a and b represent an integer of 1 or more.)
Proceed according to. Since the thiol group and the isocyanate group react with each other at a ratio of 1: 1, a polythiourethane oligomer having a larger molecular weight is generated as the molar ratio of the thiol group to the isocyanate group is closer to 1. The mixing ratio of polythiol and polyisocyanate is preferably in the range of 0.2 to 0.95 mol of isocyanate group, more preferably in the range of 0.4 to 0.95 mol, with respect to 1 mol of thiol group. If it is less than 0.2 mol, the conversion rate of the thiol group is too low to be practical, and if it exceeds 0.95 mol, an unreacted isocyanate group remains, which is not preferable.

  The reaction between polythiol and polyisocyanate proceeds by heating in the presence or absence of a catalyst, but a method using a catalyst is preferred. Examples of the catalyst include tin compounds such as dibutyltin dilaurate and dibutyldichlorotin, and basic compounds such as amine and phosphine. The amount of the catalyst used is preferably in the range of 0.01 to 10 parts by weight and more preferably in the range of 0.1 to 1.0 parts by weight with respect to 100 parts by weight of the raw polythiol.

  The reaction between polythiol and polyisocyanate may be carried out in the presence of an episulfide compound (component B). In the reaction of polythiol and polyisocyanate, a solvent may be used as necessary. When using a solvent, a post-process for distilling off the solvent is required. Although reaction temperature is not specifically limited, The range of 0-100 degreeC is preferable, and you may raise temperature gradually, seeing the progress of reaction. The reaction time depends on various conditions such as the type of raw material, the mixing ratio of polythiol and polyisocyanate, and the reaction temperature, but cannot be defined unconditionally, but the reaction is continued until no unreacted polyisocyanate remains.

（式中、ｍは０から６の整数、ｎは０から４の整数であり、Ｒ^３およびＲ^４はそれぞれ独立に、水素原子または炭素数１〜１０のアルキル基であり、Ｒ^５およびＲ^６はそれぞれ独立に炭素数１〜１０のアルキレン基である。）
で表わされる化合物が好ましい。一般式（４）で表わされるエピスルフィド化合物の例としては、ビス（２，３−エピチオプロピル）スルフィド等が挙げられる。Next, the curable composition of this invention is demonstrated.
The curable composition of the present invention includes the polythiourethane oligomer (A component), the episulfide compound (B component), and the photobase generator (C component) described above.
An episulfide compound (component B) is a compound having one or more episulfide groups in one molecule. In particular, when pursuing higher refractive index of the curable composition, the following general formula (4)

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 and 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 (4) include bis (2,3-epithiopropyl) sulfide.

  Although the episulfide compound represented by the general formula (4) has a large shrinkage due to curing, the shrinkage due to the curing can be suppressed by copolymerizing with the polythiourethane oligomer. In addition, the episulfide compound represented by the general formula (4) generally has a low viscosity, but is adjusted to a viscosity excellent in workability by mixing with the polythiourethane oligomer.

  Assuming use of the curable composition as an adhesive, if the viscosity is too low, the adhesive may sag or flow, or the substrate may be displaced during bonding. 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 as referred to in the present invention depends on the use form of the adhesive such as the coating method and the laminating method, but cannot be defined unconditionally, but is preferably in the range of 500 to 20,000 mPa · s, more Preferably it is the range of 500-10,000 mPa * s.

  About content of a polythiourethane oligomer, the range of 10-70 weight part is preferable with respect to 100 weight part of curable compositions, and the range of 20-60 weight part is further more preferable. If the content of the polythiourethane 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.

（式中、Ａｒ^１は、フェニル、ビフェニル、ナフチル、フェナントリル、アントラシル、ピレニル、５，６，７，８−テトラヒドロ−２−ナフチル、５，６，７，８−テトラヒドロ-１-ナフチル、チエニル、ベンゾ［ｂ］チエニル、ナフト［２，３−ｂ］チエニル、チアトレニル、ジベンゾフリル、クロメニル、キサンテニル、チオキサンチル、フェノキサチイニル、ターフェニル、スチルベニルまたはフルオレニルであって、これらの基は非置換であるか、またはＣ１〜Ｃ１８アルキル、Ｃ３〜Ｃ１８アルケニル、Ｃ３〜Ｃ１８アルキニル、Ｃ１〜Ｃ１８ハロアルキル、ＮＯ_２、ＯＨ、ＣＮ、ＯＲ^７、ＳＲ^８、Ｃ（Ｏ）Ｒ^９、Ｃ（Ｏ）ＯＲ^１０もしくはハロゲンによって１回以上置換されており、Ｒ^７〜Ｒ^１０はそれぞれ独立に水素またはＣ１〜Ｃ１８アルキルである。）

（式中、Ａｒ^２は、フェニル、ナフチル、アントリルまたはアントラキノニルであって、これらの基は非置換であるか、またはＣ１〜Ｃ４アルキル、Ｃ２〜Ｃ４アルケニル、ＮＯ_２、ＣＮ、ＯＲ^１１、ＳＲ^１２、Ｃ（Ｏ）Ｒ^１３、Ｃ（Ｏ）ＯＲ^１４、もしくはハロゲンによって１回以上置換されており、Ｒ^１１〜Ｒ^１４はそれぞれ独立に水素またはＣ１〜Ｃ４アルキルであり、Ｒ^１５は水素またはＣ１〜Ｃ６アルキルである。）The photobase generator (component C) 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 (5)) forming the tetraarylborate salt described in JP-T-2001-513765 and the aryl described in JP-T-2005-511536. Examples include 1,3-diamine (left side of the following formula (6)) substituted with an alkyl group. 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.

Wherein Ar ¹ is phenyl, biphenyl, naphthyl, phenanthryl, anthracyl, pyrenyl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, Benzo [b] thienyl, naphtho [2,3-b] thienyl, thiatrenyl, dibenzofuryl, chromenyl, xanthenyl, thioxanthyl, phenoxathiinyl, terphenyl, stilbenyl or fluorenyl, these groups being unsubstituted or C1 - C18 alkyl,, C3~C18 alkenyl, C3～C18 alkynyl, C1 - C18 _{^{haloalkyl, NO 2, OH, CN,}} oR 7, SR 8, C (O) R 9, C (O) oR 10 or is substituted one or more times by ^halogen, water R 7 ^{to R 10} are each independently Or C1~C18 alkyl.)

Wherein Ar ² is phenyl, naphthyl, anthryl or anthraquinonyl and these groups are unsubstituted or C 1 -C 4 alkyl, C ₂ -C 4 alkenyl, NO ₂ , CN, OR ¹¹ , SR ¹² , C (O) R ¹³ , C (O) OR ¹⁴ , or halogen one or more times, R ^{11 to} R ¹⁴ are each independently hydrogen or C 1 to C 4 alkyl, and R ¹⁵ is hydrogen or C 1 ~ C6 alkyl.)

  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 in the range of 0.01 to 10 parts by weight and more preferably in the range of 0.1 to 5 parts by weight with respect to 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 film were measured using an Abbe refractometer NAR-3T (manufactured by Atago Co., Ltd.). The transmittance of the cured film 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.

で表わされる光塩基発生剤０．５ｇ（Ｃ成分）、および増感剤として４−ベンゾイル−４’−メチルジフェニルスルフィド１ｇを加えて、均一になるまで撹拌した。以上の手順で硬化性組成物を作製した。Example 1
In a 300 ml flask, 25 g of 2,5-dimercaptomethyl-1,4-dithiane, 15 g of m-xylylene diisocyanate and 0.1 g of dibutyltin dilaurate were taken, and stirring was continued at 60 ° C. for 24 hours. After confirming that IR absorption (2280 cm ⁻¹ ) of the isocyanate group disappeared with an infrared spectrophotometer, 60 g of bis (2,3-epithiopropyl) sulfide, the following structural formula (7)

And 1 g of 4-benzoyl-4′-methyldiphenyl sulfide 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, 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 curable composition and the cured film were as shown in Table 1.

Examples 2-5
A curable composition and a cured film were prepared in the same manner as in Example 1 except that the types and amounts of polythiol, polyisocyanate, and episulfide compound were changed to those shown in Table 1. The physical properties of the curable composition and the cured film were as shown in Table 1.

Comparative Example 1
100 g of bis (2,3-epithiopropyl) sulfide, 0.5 g of photobase generator represented by the structural formula (7) (C component), 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 film was produced in the same manner as in Example 1. The physical properties of the curable composition and the cured film were as shown in Table 2. In addition, physical properties that are inferior to those of the examples are underlined.

Comparative Example 2
2,5-dimercaptomethyl-1,4-dithiane 20 g, bis (2,3-epithiopropyl) sulfide 80 g, photobase generator 0.5 g (component C) represented by the structural formula (7), 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 film was produced in the same manner as in Example 1. The physical properties of the curable composition and the cured film were as shown in Table 2. In addition, physical properties that are inferior to those of the examples are underlined.

Explanation of Abbreviations in Table (a-1) 2,5-Dimercaptomethyl-1,4-dithiane (a-2) Pentaerythritol tetrakis (3-mercaptopropionate)
(A-3) m-xylylenedithiol (a-4) 1,5-dimercapto-3-thiapentane (b-1) m-xylylene diisocyanate (b-2) 1,3-bis (2-isocyanato-2 -Propyl) cyclohexane (b-3) 1,3-bis (2-isocyanato-2-propyl) benzene (b-4) isophorone diisocyanate (c-1) bis (2,3-epithiopropyl) sulfide

Claims (5)

An optical adhesive comprising a curable composition containing a polythiourethane oligomer (A component), an episulfide compound (B component) and a photobase generator (C component) obtained by reacting polythiol and polyisocyanate. ,
The optical adhesive, 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):

(In the formula, p1 and p2 each independently represent an integer of 0 to ₁ , and X _{1 to} X ₈ each independently represent 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 optical adhesion according to claim 1 , wherein the ratio of the polythiol and the polyisocyanate when the polythiol and the polyisocyanate are reacted is within a range of 0.2 to 0.95 mol of the isocyanate group with respect to 1 mol of the thiol group. Agent . The optical adhesive according to claim 1 or 2 , wherein the episulfide compound (component B) is a compound represented by the following general formula (4).

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 and R 4 ⁶ is each independently an alkylene group having 1 to 10 carbon atoms.) The optical adhesive according to claim 3 , wherein the compound represented by the general formula (4) is bis (2,3-epithiopropyl) sulfide. The optical adhesive according to any one of claims 1 to 4 , wherein the photobase generator (component C) is a compound represented by the following general formula (8) or (9).

Wherein Ar ¹ is phenyl, biphenyl, naphthyl, phenanthryl, anthracyl, pyrenyl, 5,6,7,8-tetrahydro-2-naphthyl, 5,6,7,8-tetrahydro-1-naphthyl, thienyl, Benzo [b] thienyl, naphtho [2,3-b] thienyl, thiatrenyl, dibenzofuryl, chromenyl, xanthenyl, thioxanthyl, phenoxathiinyl, terphenyl, stilbenyl or fluorenyl, these groups being unsubstituted or C1 - C18 alkyl,, C3~C18 alkenyl, C3～C18 alkynyl, C1 - C18 _{^{haloalkyl, NO 2, OH, CN,}} oR 7, SR 8, C (O) R 9, C (O) oR 10 or is substituted one or more times by ^halogen, water R 7 ^{to R 10} are each independently Or C1~C18 alkyl.)

Wherein Ar ² is phenyl, naphthyl, anthryl or anthraquinonyl and these groups are unsubstituted or C 1 -C 4 alkyl, C ₂ -C 4 alkenyl, NO ₂ , CN, OR ¹¹ , SR ¹² , C (O) R ¹³ , C (O) OR ¹⁴ , or halogen one or more times, R ^{11 to} R ¹⁴ are each independently hydrogen or C 1 to C 4 alkyl, and R ¹⁵ is hydrogen or C 1 ~ C6 alkyl.)