TWI515232B - A hardening composition and an optical follower - Google Patents

Description

Curing composition and optical adhesive

The present invention relates to an optical adhesive used in the production of a composite optical element.

A photocurable composition containing an acrylate compound or the like as a main component has been widely used as an adhesive when an optical element is produced. In the case of the adhesive, the basic properties are adhesion, hardenability, mechanical strength, durability, and optical properties, but in recent years, as the optical element has been highly functionalized, the refractive index has become an important performance. In particular, the high refractive index of the adhesive agent has a high degree of freedom in optical design and is expected to be high. An example of a composite optical element using an adhesive having a high refractive index is an achromatic lens formed by bonding two lenses, a composite aspheric lens composed of a composite of glass and resin, and a two-color enamel ( Dichroic prism) and the like having complex shapes.

The adhesive used in such applications requires not only a high refractive index but also a property of adhesion, photocurability, colorless transparency, and heat resistance.

As the polyfunctional (meth) acrylate compound having a high refractive index, 9,9-bis(4-(2-propenyl methoxyethoxy)phenyl) fluorene (hereinafter referred to as A-BPEF) is known. (refractive index: 1.62), or 4,4'-bis(methacrylium sulfenyl)diphenyl sulfide (hereinafter referred to as MPSMA) (refractive index: 1.69). However, these compounds are solid at normal temperature and are therefore difficult to use alone.

Further, these compounds obtain a rigid cured product due to the structure of an anthracene ring or a diphenyl sulfide. When it is used as an adhesive, it is likely to cause peeling at the subsequent interface when cracking in the adhesive layer occurs when an impact force such as dropping is applied to the immediately succeeding layer.

Further, a general polyfunctional (meth) acrylate compound shrinks greatly as it hardens, and when used as an adhesive, it causes a decrease in adhesion.

On the other hand, it is known to combine an ethylenically unsaturated compound such as a (meth) acrylate compound with an olefin of a thiol compound. In the thiol composition, since the thiol compound contains a sulfur atom having a high atomic refractive index, a cured product having a high refractive index is obtained. And, known as alkenes. The thiol composition shrinks less as it hardens, and a soft cured product can be obtained.

However, the addition polymerization of a thiol group and an ethylenically unsaturated bond group has less crosslinking points than the chain polymerization, and the resulting thioether bond has a tendency to obtain a soft cured product, so that the obtained cured product is at a high temperature. It is easy to soften the subject. In order to obtain sufficient heat resistance, it is necessary to select a polyfunctional ethylenically unsaturated compound and a thiol compound.

Patent Document 1 describes an olefin composed of a difunctional thiol compound containing a 1,4-dithiane ring, and triallyl isocyanurate or triallyl cyanurate. Mercaptan composition. However, the refractive index of the cured product is not specifically described.

Patent Document 2 describes an alkene composed of A-BPEF, an ethylenically unsaturated compound, and a thiol compound. Mercaptan composition. When demonstrated by the examples, the refractive index of the cured product is as high as 1.58 to 1.61.

Patent Document 3 describes an olefin composed of MPSMA, a vinyl monomer, and a polythiol. Mercaptan composition. When demonstrated by way of example, the cured product has a refractive index of up to 1.649. However, MPSMA tends to yellow, and because of its solidity, there is a limit to the amount of dissolution of the composition. Moreover, the peeling transfer temperature of the cured product is as high as 127 to 157 ° C, and lacks flexibility.

Further, Patent Document 4 describes a resin composition comprising a resin component having an anthracene ring and a sulfur-containing compound having a diphenyl sulfide skeleton such as MPSMA, and a resin having a refractive index of 1.724 is exemplified. However, the resin composition in the invention is a thermoplastic resin obtained by kneading a polyester having an anthracene ring and a sulfur-containing compound, and is not a curable resin composition, and of course, it cannot provide photocurability.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2000-154251

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-254732

[Patent Document 3] Japanese Patent Publication No. 03-021638

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2005-187661

Accordingly, an object of the present invention is to provide a curable property as an optical adhesive for a higher refractive index and also having photocurability, low hardening shrinkage, flexibility, colorless transparency, and heat resistance. Composition.

The inventors of the present invention have actively reviewed the results of the above problems, and found that a specific polythiol compound and a trifunctional or higher olefin compound are formed. The thiol composition not only has a high refractive index, but also has the necessary properties as an optical adhesive. Further, it has been found that by containing an ethylenically unsaturated bond compound having a bis(thiophenyl) sulfide structure or a bis(thiophenyl)fluorene structure, on the one hand, the physical property balance can be maintained, and the refractive index can be further increased. The present invention has been completed based on the above findings.

According to the first aspect of the present invention, it is possible to provide a curable composition having a refractive index higher than that in the past and having photocurability, colorless transparency, and heat resistance as an optical adhesive, or The second aspect provides a curable composition which has a refractive index higher than that in the past and which also has photocurability, low hardening shrinkage, flexibility, and colorless transparency as an optical adhesive.

The curable composition of the present invention comprises a specific polythiol compound (component A) and a trifunctional or higher alkyl compound (component B). Further, it is preferred to contain an ethylenically unsaturated bond compound (component C) having a bis(thiophenyl) sulfide structure or a di(thiophenyl)fluorene structure.

The specific polythiol compound (component A) is a compound represented by the following formula (1a) in the first state:

(wherein, p1 and p2 each independently represent an integer of 0 to 1, and further, X1 to X8 each independently represent a hydrogen atom or a methylthiol group, and any one represents a methylthiol group).

In the second aspect, the specific thiol compound (component A) is a compound represented by the following formula (1b):

(wherein, m represents an integer of 0 to 3, R ¹ represents an alkylene group having 1 to 3 carbon atoms), or a compound represented by the following formula (1c)

(wherein, n represents an integer of 0 to 3, and R ² represents an alkyl group having only a bond or a carbon number of 1 to 3).

The compound represented by the formula (1a) has three or more thiol groups in one molecule.

Further, the compound represented by the formula (1a) is equivalent to the compound represented by the following formula (1d).

(wherein, p represents an integer of 2 to 4, and Xp and Yp each independently represent a hydrogen atom or a methylthiol group, and any one represents a methylthiol group).

Examples of the compound represented by the formula (1a) are 2-mercaptomethyl-1,5-dimercapto-3-thiopentane and 2,4-bis(indolylmethyl)-1,5-diindenyl- 3-thiopentane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiooctane, 4,8-bis(indolylmethyl)-1,11-dimercapto-3,6, 9-trithioundecane, 4,7-bis(indolylmethyl)-1,11-dimercapto-3,6,9-trithioundecane, 5,7-bis(indolylmethyl)-1 , 11-dimercapto-3,6,9-trithioundecane, and the like.

The compound represented by the formula (1b) is exemplified by toluene dithiol or the like, and the compound represented by the formula (1c) is exemplified by 2,5-bis(dimercaptomethyl)-1,4-disulfide. Heterocyclic hexane and the like.

Since the component A contains a sulfur atom having a large atomic refraction at a high concentration, the effect of the refractive index is large. Further, since the thiol group has an antioxidant effect, it suppresses yellowing deterioration of the cured product due to heat or light. In addition, since the compound represented by the general formulae (1a) and (1d) has three or more thiol groups, it has sufficient crosslinkability to obtain a cured product excellent in heat resistance.

The trifunctional or higher olefinic compound (component B) is a compound having three or more ethylenically unsaturated bond groups in one molecule, and the ethylenically unsaturated bond group is exemplified by an acryloyl group, a methacryloyl group, a vinyl group, or the like. Allyl Wait. In particular, when purifying the high refractive index of the curable composition, it is preferably a compound having an aromatic ring or a hetero ring in the molecule, and examples of the compound are triallyl isocyanurate and cyanuric acid triene. Propyl ester, triallyl trimellitate, tetraallyl pyromellitate, and the like.

The ethylenically unsaturated bond compound (component C) having a bis(thiophenyl) sulfide structure or a di(thiophenyl)fluorene structure is a compound represented by the following formula (2).

(wherein X represents a sulfur atom or a sulfonyl group, and Z represents a (meth)acryloyl group, a vinyl group or an allyl group). Examples of the compound represented by the formula (2) are 4,4'-bis(methacrylium sulfenyl)diphenyl sulfide.

The blending ratio of the component A, the component B, and the component C is 1 mol with respect to the ethylenically unsaturated bond group contained in the component B and the component C, and the thiol group contained in the component A is preferably in the range of 0.5 to 1.5 mol. It is better to range from 0.8 to 1.2 moles. When the amount of the component A is less than 0.5 mol, the effect of the component A is small and it is not practical, and when it exceeds 1.5 mol, the unreacted thiol group tends to remain, which is not preferable.

The curable composition of the present invention can be obtained by uniformly mixing the components at normal temperature or under heating according to a usual method. The mixed composition can also be filtered or defoamed as needed.

The curable composition of the present invention may optionally contain a polymerization inhibitor, an antioxidant, a light stabilizer (HALS), an ultraviolet absorber, a decane coupling agent, a release agent, a pigment, a dye, and the like.

The curable composition of the present invention is cured by irradiation with active light 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 is free radical which generates activity by photolysis. Specific examples of such a compound are exemplified by 2,2-methoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1. -Phenylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylpropan-1-one, 2-benzyl-2-dimethylamino 1-(4-morpholinylphenyl)-1-butanone, bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide, 2,4,6-trimethylbenzene Mercapto-diphenyl-phosphine oxide and the like. The radical photopolymerization initiator may be used singly or in combination of two or more. The content thereof is not particularly limited, but is preferably in the range of 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the curable composition.

[Examples]

The invention will be specifically described below by way of examples, but the invention is not limited thereto. Further, the curing shrinkage ratio in the examples was calculated from the refractive index before and after curing according to the following calculation formula.

X=(1-d1/d2)×100[%]

R=(n ² -1)/(n ² +2)×M/d

The R/M before and after hardening is constant, so from the above two formula, X=[1-{(n1 ² -1)/(n1 ² +2)}/{(n2 ² -1)/(n2 ² +2) }]×100[%]

(wherein X represents the hardening shrinkage ratio, d represents the specific gravity, d1 represents the specific gravity before hardening, d2 represents the specific gravity after hardening, and R represents molecular refraction, n The refractive index is represented, n1 represents the refractive index before hardening, n2 represents the refractive index after hardening, and M represents the molecular weight).

Further, the refractive index of the curable composition and the cured film was measured using an Abbe refractometer NAR-3T (manufactured by ATAGO Co., Ltd.). The transmittance of the cured film was measured by using a spectrophotometer U-3500 (manufactured by Hitachi High-Technologies Corporation) at a thickness of 0.25 mm and a wavelength of 400 nm. The glass transition temperature and the modulus of elasticity of the cured film were measured using a viscoelastic analyzer DMS6100 (manufactured by SEIKO INSTRUMENT Co., Ltd.) at a temperature elevation rate of 2 ° C/min and a frequency of 1 Hz. The peak temperature of tan δ was taken as the glass transition temperature, and the storage elastic modulus at 25 ° C was taken as the modulus of elasticity.

Example 1

43 parts by weight of a 2,4-bis(mercaptomethyl)-1,5-dimercapto-3-thiopentane (component A) and 57 parts by weight of triallyl cyanurate were fed into a 300 ml flask (component B) And 3 g of 1-hydroxy-cyclohexyl phenyl ketone, and the mixture was stirred until uniform to prepare a curable composition. A cured film was produced in the above order.

The hardened composition was sandwiched between two sheets of the release-treated glass plate, and the light of the metal halide lamp (120 W/cm) was irradiated 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 in the above procedure.

The physical properties of the curable composition and the cured film are shown in Table 1.

Example 2~6

Change the type and feed amount of component A, component B, and component C to The curable composition and the cured film were produced in the same manner as in Example 1 except for the contents shown in Table 1. The physical properties of the curable composition and the cured film are shown in Tables 1 and 2.

Comparative example 1

The curable composition and the cured film were produced in the same manner as in Example 1 except that the types and the amounts of the components A and B were changed to those shown in Table 1. The physical properties of the curable composition and the cured film are shown in Table 2. Also, compared with the embodiment, the value of the poor performance is added to the bottom line.

Example 7

45 g of m-toluene dithiol (component A), 55 g of triallyl trimellitate (component B), and 3 g of 1-hydroxy-cyclohexyl phenyl ketone were placed in a 300 ml flask, and the mixture was stirred until uniform to prepare a curable composition. Things. A cured film was produced in the above order.

The hardened composition was sandwiched between two sheets of the release-treated glass plate, and the light of the metal halide lamp (120 W/cm) was irradiated 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 in the above procedure.

The physical properties of the curable composition and the cured film are shown in Table 3.

Examples 8-9

The curable composition and the cured film were produced in the same manner as in Example 7 except that the types and the amounts of the components A and B and the amount of the components fed were changed to those shown in Table 3. The physical properties of the curable composition and the cured film are shown in Table 3.

Comparative example 2

The curable composition and the cured film were produced in the same manner as in Example 7 except that the types and the amounts of the components A and B and the amount of the components fed were changed to those shown in Table 3. The physical properties of the curable composition and the cured film are shown in Table 3. Also, compared with the embodiment, the value of the poor performance is added to the bottom line.

Description in Table 1 and Table 2

A-1: 2,4-bis(decylmethyl)-1,5-dimercapto-3-thiopentane

A-2: 4-mercaptomethyl-1,8-dimercapto-3,6-dithiooctane

A-3: 4,8-bis(decylmethyl)-1,11-dimercapto-3,6,9-trithioundecane, 4,7-bis(fluorenylmethyl)-1,11-di Isomer mixture of mercapto-3,6,9-trithioundecane and 5,7-bis(decylmethyl)-1,11-dimercapto-3,6,9-trithioundecane

B-1: triallyl cyanurate

B-2: triallyl isocyanurate

B-3: triallyl trimellitate

B-4: tetraallyl pyromellitic acid

B-5: 2,2-bis(4-(acryloxydiethoxy)phenyl)propane

C-1: 4,4'-bis(methacryloylthio)diphenyl sulfide

Description of the abbreviations in Table 3

A'-1: m-toluenediethanol

A'-2: 2,5-bis(dimercaptomethyl)-1,4-dithiane

A'-3: 4-mercaptomethyl-1,8-dimercapto-3,6-dioxin

B'-1: triallyl trimellitate

B'-2: triallyl isocyanurate

B'-3: 2,2-bis(4-(acryloxydiethoxy)phenyl)propane

C'-1: 4,4-bis(methacrylium sulfenyl)diphenyl sulfide

Claims (10)

A curable composition containing a polythiol compound (component A) represented by the following formula (1a) and a trifunctional or higher olefinic compound (component B). In the formula, p1 and p2 each independently represent an integer of 0 to 1, and further, X1 to X8 each independently represent a hydrogen atom or a methylthiol group, and any one represents a methylthiol group. A sclerosing composition according to claim 1, wherein the polythiol compound represented by the formula (1a) (component A) is 2-mercaptomethyl-1,5-dimercapto-3-thiopentane , 2,4-bis(decylmethyl)-1,5-dimercapto-3-thiopentane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiooctane, 4,8 - bis(decylmethyl)-1,11-dimercapto-3,6,9-trithioundecane, 4,7-bis(decylmethyl)-1,11-dimercapto-3,6,9 One or more compounds selected from the group consisting of trithioundecane and 5,7-bis(decylmethyl)-1,11-dimercapto-3,6,9-trithioundecane. The sclerosing composition of the first or second aspect of the patent application, wherein the trifunctional or higher olefinic compound (component B) is a triallyl isocyanurate, a triallyl cyanurate, a trimellitic acid One or more compounds selected from the group consisting of triallyl acylate and tetraallyl pyromellitate. The curable composition of claim 1 or 2, which further comprises a compound represented by the following formula (2), In the formula, X represents a sulfur atom or a sulfonyl group, and Z represents a (meth)acrylonitrile group, a vinyl group, or an allyl group. The curable composition of claim 3, which further comprises a compound represented by the following formula (2), In the formula, X represents a sulfur atom or a sulfonyl group, and Z represents a (meth)acrylonitrile group, a vinyl group, or an allyl group. An optical adhesive comprising the curable composition according to any one of claims 1 to 5. A curable composition containing a polythiol compound (component A) represented by the following formula (1b) and a trifunctional or higher olefinic compound (component B), and further containing a compound represented by the following formula (2) ; Wherein m represents an integer of 0 to 3, and R ¹ represents an alkylene group having 1 to 3 carbon atoms; In the formula, X represents a sulfur atom or a sulfonyl group, and Z represents a (meth)acrylonitrile group, a vinyl group, or an allyl group. A curable composition containing a polythiol compound (component A) represented by the following formula (1c) and a trifunctional or higher olefinic compound (component B), and further containing a compound represented by the following formula (2) ; Formula, n represents an integer of 0 to 3, R ² represents a bond or only 1-3 carbon atoms, alkyl of extension; In the formula, X represents a sulfur atom or a sulfonyl group, and Z represents a (meth)acrylonitrile group, a vinyl group, or an allyl group. The sclerosing composition of the seventh or eighth aspect of the patent application, wherein the trifunctional or higher olefinic compound (component B) is a triallyl isocyanurate, a triallyl cyanurate, a benzotriene One or more compounds selected from the group consisting of triallyl acylate and tetraallyl pyromellitate. An optical adhesive comprising the curable composition according to any one of claims 7 to 9.