JP5991315B2 - 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.

  A photocurable composition mainly composed of an acrylate compound or the like is widely used as an adhesive for producing an optical element. For adhesives, adhesiveness, curability, mechanical strength, durability, and optical properties are basic performances, but in recent years, the refractive index has become an important performance as the functionality of optical elements increases. 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 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 are known. 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, it is known that an ene / thiol composition obtained by combining an ethylenically unsaturated compound such as a (meth) acrylate compound and a thiol compound has a small shrinkage due to curing.

Patent Document 1 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 2 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 3 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.

JP 2010-254732 A JP 03-021638 A 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 viscosity, low shrinkage, and colorless transparency suitable for work. It is in.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have cured a polythiol oligomer (A component) obtained by reacting an episulfide compound and a thiol compound and an ethylenically unsaturated compound (B component). It has been found that the adhesive composition is suitable as an optical adhesive because it has a viscosity suitable for workability as an adhesive and has a small shrinkage due to curing. Based on the above findings, the present invention has been achieved.

  According to the present invention, it is possible to provide a curable composition having a high refractive index and also having performance as an optical adhesive such as viscosity, low shrinkage, and colorless transparency suitable for work.

  The curable composition of the present invention comprises a polythiol oligomer (A component) obtained by reacting an episulfide compound and a thiol compound, and an ethylenically unsaturated compound (B component).

（式中、ｍは０から６の整数であり、ｎは０から４の整数、Ｒ^１およびＲ^２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^３およびＲ^４はそれぞれ独立に炭素数１〜１０のアルキレン基を表す。）
で表わされる化合物が好ましい。一般式（１）で表わされる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。First, the manufacturing method of a polythiol oligomer (A component) is demonstrated.
The episulfide compound used as a raw material for the polythiol oligomer is a compound having one or more episulfide groups in one molecule. In particular, when pursuing higher refractive index and crosslinkability of the curable composition, the following general formula (1)

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

（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^５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^６は炭素数１〜３のアルキレン基を表す。）The thiol compound used as a raw material for the polythiol oligomer is a compound having one or more thiol groups in one molecule, which may be linear, branched or cyclic, and two in one molecule. A polythiol compound having the above thiol group is preferred.
In particular, when pursuing a viscosity suitable for increasing the refractive index and workability of the curable composition, polythiol compounds represented by the following general formulas (2) to (4) 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 ⁵ 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 ⁶ represents an alkylene group having 1 to 3 carbon atoms.)

  Examples of the compound represented by the general formula (2) 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 (3) 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 (4), xylylenedithiol and the like. Examples of polythiol compounds other than the compounds represented by the general formulas (2) to (4) include ethylene glycol bis (3-mercaptopropionate), trimethiolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3 -Mercaptopropionate), benzenedithiol, tolylenedithiol and the like.

（式中、ＲおよびＲ’は有機基を表し、ａおよびｂは０以上の整数を表す。）
に従って進行する。エピスルフィド基とチオール基が反応して２級のチオール基が生成する。エピスルフィド化合物とチオール化合物の混合比は、エピスルフィド基１モルに対してチオール基が１．０〜２．０モルの範囲が好ましい。１．０モル未満では、未反応のエピスルフィド基が残存して好ましくないし、２．０モルを超えると得られるポリチオールオリゴマーの粘度が低下して好ましくない。For example, when the product is a dimer, the reaction of the episulfide compound and the thiol compound is represented by the following reaction formula:

(In the formula, R and R ′ represent an organic group, and a and b represent an integer of 0 or more.)
Proceed according to. The episulfide group and the thiol group react to produce a secondary thiol group. The mixing ratio of the episulfide compound and the thiol compound is preferably in the range of 1.0 to 2.0 mol of the thiol group with respect to 1 mol of the episulfide group. If it is less than 1.0 mol, an unreacted episulfide group remains unpreferable, and if it exceeds 2.0 mol, the viscosity of the polythiol oligomer obtained is lowered, which is not preferable.

  The reaction between the episulfide compound and the thiol compound proceeds by heating in the presence or absence of a catalyst, but a method using a catalyst is preferred. The catalyst is preferably a basic compound, and examples thereof include amines, ammonium salts, phosphines, and phosphonium salts. The amount of the catalyst used is preferably in the range of 0.005 to 5 parts by weight and more preferably in the range of 0.05 to 0.5 parts by weight with respect to 100 parts by weight of the total amount of the episulfide compound and the thiol compound.

  The reaction between the episulfide compound and the thiol compound may be performed in the presence of an ethylenically unsaturated compound (component B). Moreover, you may use a solvent as needed. 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 the episulfide compound and the thiol compound, and the reaction temperature, but cannot be defined unconditionally, but a range of 30 minutes to 24 hours is preferable.

Next, the curable composition of this invention is demonstrated.
The curable composition of the present invention comprises the polythiol oligomer (A component) described above and an ethylenically unsaturated compound (B component).

（式中、Ｘは硫黄原子またはスルホニル基を表し、Ｚは（メタ）アクリロイル基、ビニル基、またはアリル基を表わす。）

（式中、ｓおよびｔは、ｓとｔの合計が０〜４を満たす整数を表し、Ｒ^７は炭素数１〜５のアルキレン基を表し、Ｒ^８は水素原子またはメチル基を表し、Ｒ^９は水素原子またはメチル基を表す。）An ethylenically unsaturated compound (component B) is a compound having two or more ethylenically unsaturated bonds in one molecule, and examples of the ethylenically unsaturated bond group include an acryloyl group, a methacryloyl group, a vinyl group, and an allyl group. Etc. 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 (5), a compound represented by general formula (6), 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, s and t represent an integer in which the sum of s and t satisfies 0 to 4, R ⁷ represents an alkylene group having 1 to 5 carbon atoms, R ⁸ represents a hydrogen atom or a methyl group, R ⁹ represents a hydrogen atom or a methyl group.)

  Examples of the compound represented by the general formula (5) 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 blending ratio of the A component and the B component is preferably in the range of 0.5 to 1.5 mol of the thiol group in the A component with respect to 1 mol of the ethylenically unsaturated bond group in the B component, 0.8 to A range of 1.2 moles is preferred. If the amount is less than 0.5 mol, the effect of the component A is small and is not practical. If the amount exceeds 1.5 mol, an unreacted thiol group tends to remain at the time of curing, which is not preferable. As can be seen from the reaction formula of the episulfide compound and the thiol compound, the total amount of thiol groups in the component A is the same as the total amount of thiol groups contained in the thiol compound used as a raw material for the polythiol oligomer.

  The curable composition of the present invention is cured by heat polymerization in the presence or absence of a curing catalyst. A preferred method is a method using a curing catalyst, and examples of the curing catalyst include compounds that generate free radicals such as organic peroxides and azo compounds, and basic compounds such as amines and phosphines. The addition amount of the curing catalyst is preferably in the range of 0.001 to 5 parts by weight and more preferably in the range of 0.01 to 1 part by weight with respect to 100 parts by weight of the curable composition. The polymerization temperature is preferably in the range of 0 to 150 ° C, more preferably in the range of 20 to 120 ° C, and the temperature may be gradually increased. Although the polymerization time depends on various conditions such as the blending ratio of the polythiol compound and the ene compound, the type and addition amount of the curing catalyst, the weight of the curable composition, the polymerization temperature, etc., it cannot be defined unconditionally, but 10 minutes to 50 hours The range of 30 minutes to 24 hours is more preferable.

  In addition, the curable composition of the present invention can be 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) -butanone-1, 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. Although the content is not specifically limited, The range of 0.1-10 weight part is preferable with respect to 100 weight part of curable compositions, The range of 0.5-5 weight part is more 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.

  Assuming that the viscosity of the curable composition is used as an adhesive, if the viscosity is too low, the adhesive may sag or flow, or the adherend may be displaced during lamination, 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 pasting. The viscosity suitable for workability in the present invention depends on the use form of the adhesive such as a coating method and a bonding method, and thus cannot be defined unconditionally, but is preferably in the range of 500 to 10,000 mPa · s.

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 measurement wavelength of 400 nm.

Example 1
In a 300 ml flask, 28 g of bis (2,3-epithiopropyl) sulfide, 35 g of 1,5-dimercapto-3-thiapentane, and 0.5 g of dicyclohexylmethylamine were taken, and stirring was continued at 60 ° C. for 24 hours. The polythiol oligomer was produced by the above procedure.
To this, 37 g of triallyl isocyanurate was added and stirred until uniform. The curable composition was produced in the above procedure.
To 100 parts by weight of the curable composition, 3 parts by weight of 1-hydroxy-cyclohexyl phenyl ketone was added, 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 were as shown in Table 1.

Example 2
Into a 300 ml flask is taken 33 g of bis (2,3-epithiopropyl) sulfide, 33 g of 1,5-dimercapto-3-thiapentane, 34 g of triallyl isocyanurate, and 0.5 g of dicyclohexylmethylamine and stirred at 60 ° C. for 24 hours. Continued. 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 1.

Examples 3-8
A curable composition and a cured film were prepared in the same manner as in Example 2 except that the types and amounts of the episulfide compound, polythiol compound, and ethylenically unsaturated 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
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 film 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 film 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 film were as shown in Table 2. In addition, the value which performance is inferior compared with an Example was underlined.

Explanation of Abbreviations in Table (a-1) Bis (2,3-epithiopropyl) sulfide (b-1) 1,5-dimercapto-3-thiapentane (b-2) 2,5-dimercaptomethyl-1, 4-dithiane (b-3) m-xylylene dithiol (c-1) triallyl isocyanurate (c-2) triallyl trimellitic acid (c-3) diallyl phthalate (c-4) 4,4′-bis ( Methacryloylthio) diphenyl sulfide (c-5) 2,2-bis (4- (acryloxydiethoxy) phenyl) propane

Claims (6)

A curable composition containing a polythiol oligomer (A component) obtained by reacting an episulfide compound and a thiol compound, and an ethylenically unsaturated compound (B component) ,
The episulfide compound is represented by the following general formula (1)

Wherein m is an integer from 0 to 6, n is an integer from 0 to 4, R ¹ and R ² are each independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ³ and R ⁴ each independently represents an alkylene group having 1 to 10 carbon atoms.)
The said curable composition which is a compound represented by these . The curable composition according to claim 1 , wherein the compound represented by the general formula (1) is bis (2,3-epithiopropyl) sulfide. The curable composition according to claim 1 or 2 , wherein the thiol compound is selected from the group consisting of compounds represented by the following general formula (2), general formula (3), and general formula (4).

(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 ⁵ 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 ⁶ represents an alkylene group having 1 to 3 carbon atoms.) A compound in which the ethylenically unsaturated compound (component B) is represented by the formula (5) The curable composition according to any one of claims 1 to 3 , which is at least one selected from the group consisting of a compound represented by formula (6):

(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, s and t represent an integer in which the sum of s and t satisfies 0 to 4, R ⁷ represents an alkylene group having 1 to 5 carbon atoms, R ⁸ represents a hydrogen atom or a methyl group, R ⁹ represents a hydrogen atom or a methyl group.) The blending ratio of the polythiol oligomer (component A) and the ethylenically unsaturated compound (component B) is such that the thiol group in the component A is 0.5 to 1. with respect to 1 mol of the ethylenically unsaturated bond group in the component B. The curable composition in any one of Claim 1 to 4 which is the range of 5 mol. The optical adhesive agent containing the curable composition in any one of Claim 1 to 5 .