JP2001194510A - Joined optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joined optical element less liable to yellowing with little variation in products. SOLUTION: The joined optical element is obtained by joining with a photo- curable resin composition containing (1) a prepolymer having a carbon-carbon double bond and a mercapto group obtained by reacting a polyene with a polythiol and (2) a photopolymerization initiator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bonded optical element used for cameras, binoculars, microscopes, etc. by bonding two or more optical elements such as lenses and prisms. More specifically, polyene
The present invention relates to a bonded optical element bonded using a polythiol-based photocurable resin composition.

[0002]

2. Description of the Related Art As a bonded optical element in which optical elements are bonded, there are glass to glass, a combination of glass and plastic, and plastic to plastic. As a method for joining optical elements, there is a method using an adhesive made of a photocurable resin composition.

Examples of the photocurable resin composition include a polyene / polythiol-based photocurable resin composition comprising a polyene, a polythiol and a photopolymerization initiator.
It is used for paints, adhesives, sealants, etc. (JP-B-63-20255).

[0004]

TECHNICAL FIELD The photocurable resin composition comprises 1
Since it is a liquid type, it is convenient to mix the main agent and the curing agent when using it, and it is convenient because it cures in a short time of several seconds to several minutes by light irradiation.

However, in the conventional polyene / polythiol-based photocurable resin composition, the reaction starts at the time of mixing the polyene and the polythiol, and the reaction speed is high. Difficult, especially one with low viscosity could not be obtained.

A photocurable resin composition having a low viscosity is useful from the viewpoint of workability as an adhesive for an optical element used for bonding optical elements to produce a bonded optical element.

Therefore, as a method of obtaining a photocurable resin composition having a low viscosity, a method of adding a large amount of a reaction terminator to the photocurable resin composition can be considered.

[0008]

However, since the photocurable resin composition has a high reaction rate, it is difficult to judge when to add a reaction terminator. Was required.

Further, when a large amount of a reaction terminator is added to the photocurable resin composition, there is a problem that the resin composition turns yellow during storage. In addition, when a photocurable resin composition containing a large amount of a reaction terminator is used as an adhesive for an optical element, there has been a problem that the bonded portion of the bonded optical element is yellowed by sunlight.

[0010] Therefore, a photocurable resin composition using a small amount of a reaction terminator and a photopolymerization initiator has been desired.

As a result of intensive studies, the present inventor has found a low-viscosity photocurable resin composition in which the amount of the reaction terminator and photopolymerization initiator used in the photocurable resin composition is as small as possible.
The present invention has been completed.

[0012]

The present invention provides (1) a prepolymer having a carbon-carbon double bond and a mercapto group obtained by previously reacting a polyene and a polythiol;
(2) A bonding optical element formed by bonding using a photocurable resin composition containing a photopolymerization initiator, wherein the viscosity of the prepolymer is 40000 mPa · s or less. And a bonding optical element formed by bonding using the photocurable resin composition in which metal ions in the prepolymer are 50 ppm or less, and further, the prepolymer reacts. A bonded optical element formed by bonding using the photocurable resin composition containing a terminator. The optical element is the cemented optical element that is a lens. Further, the bonded optical element is an optical element that is a prism.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.

The polyene of the present invention refers to a polyfunctional compound having two or more carbon-carbon double bonds in one molecule. Examples of the polyene include an allyl alcohol derivative, esters of (meth) acrylic acid and a polyhydric alcohol, urethane acrylate and divinylbenzene. One or more of these can be used.

Examples of the allyl alcohol derivative include triallyl isocyanurate, triallyl cyanurate, diallyl maleate, diallyl fumarate, diallyl adipate, diallyl phthalate, triallyl trimellitate, tetraallyl pyromellitate, glycerin diallyl ether, Methylolpropane diallyl ether,
Pentaerythritol diallyl ether and sorbitol diallyl ether;

Among the esters of (meth) acrylic acid and polyhydric alcohols, polyhydric alcohols include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin and trimethylol. And propane, pentaerythritol and sorbitol.

Of these, from the viewpoint of reactivity with polythiol, one or more selected from the group consisting of triallyl isocyanurate, triallyl cyanurate and diallyl maleate is preferred, and triallyl isocyanurate is more preferred. preferable.

The polythiol of the present invention is defined as 2
A polyfunctional compound having two or more thiol groups.
Examples of the polythiol include esters of mercaptocarboxylic acid and a polyhydric alcohol, aliphatic polythiols, aromatic polythiols, and the like. One or more of these can be used.

Among the esters of mercaptocarboxylic acid and polyhydric alcohol, mercaptocarboxylic acid includes
Thioglycolic acid, α-mercaptopropionic acid and β
-Mercaptopropionic acid and the like. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerin, trimethylolpropane, pentaerythritol and sorbitol.

Examples of the aliphatic polythiols and aromatic polythiols include ethanedithiol, propanedithiol, hexamethylenedithiol, decamethylenedithiol, tolylene-2,4-dithiol and xylenedithiol.

Of these, esters of a mercaptocarboxylic acid and a polyhydric alcohol are preferred because of their low odor.

In the prepolymer of the present invention, the ratio of the polyene to the polythiol used is such that the molar ratio of the carbon-carbon double bond group in the polyene to the thiol group in the polythiol is 5: 1 to 1: 5. , And more preferably 1: 1. If it exceeds 5: 1, the resin may be hard and brittle, and if it is less than 1: 5, the resin may be soft and the curing time may be delayed.

The viscosity of the prepolymer of the present invention is preferably 40,000 mPa · s or less at 25 ° C.
00 mPa · s is more preferable, and 250 to 1000 mP
a · s is most preferred. When the viscosity exceeds 40000 mPa · s, the step of heating the prepolymer increases when producing a photocurable resin composition having a predetermined viscosity, and the workability may be reduced. In addition, when the prepolymer of the present invention is used as an optical element adhesive used for manufacturing an optical element by bonding optical elements, the adhesive workability is reduced to 100%.
It is preferably 0 mPa · s or less.

In the prepolymer of the present invention, the amount of metal ions is preferably 50 ppm or less, more preferably 30 ppm or less. If it exceeds 50 ppm, it is difficult to adjust the viscosity,
The viscosity may not be reduced.

Among the metal ions, sodium, iron, calcium, copper, magnesium and tin greatly affect the viscosity, so that the amount of the metal ions is sodium, iron, calcium, copper, magnesium and tin ions. Is preferably represented by the total amount of

As a method of reducing the metal ion to 50 ppm or less, there is a method of washing the polyene or polythiol with an aqueous solution containing a chelating agent to chelate the metal ion and remove the metal ion.

As another method for reducing the metal ion to 50 ppm or less, polyene or polythiol that can be distilled under reduced pressure,
For example, there is a method in which a crude polyene or crude polythiol having a boiling point of 100 to 200 ° C. (400 Pa) is distilled under reduced pressure to remove metal ions.

The prepolymer (1) of the present invention is obtained by preliminarily reacting a mixture of a polyene and a polythiol to have a viscosity of 400.
00mPa · s or less, preferably 250 to 40000m
It is adjusted to Pa · s.

Examples of the method of reacting the mixture of the polyene and the polythiol in advance include a method by heating and a method of adding a small amount of a photopolymerization initiator and irradiating with ultraviolet rays. A method by heating is preferred.

As a method of heating, a method is preferred in which the reaction rate is easily controlled, preferably at 20 to 70 ° C., and the reaction is stopped by adding a reaction terminator during the reaction to adjust the viscosity. No.

Examples of the reaction terminator include N-nitrosophenyl / hydroxylamine ammonium salt, 2,6-di-
Examples include tert-butyl-4-methylphenol, 2,2-methylene-bis (4-methyl-6-tert-butylphenol), hydroquinone, and monomethyl ether. Among them, N-nitrosophenyl / hydroxylamine ammonium salt is preferable because a large effect can be obtained with a small amount of use.

The amount of the reaction terminator is preferably from 0.001 to 1.0 part by mass, more preferably from 0.03 to 1.0 part by mass, per 100 parts by mass of the total of the polyene and the polythiol, from the viewpoint of controlling the reaction rate.
0.1 parts by mass is more preferred. If the amount is less than 0.001 part by mass, the reaction rate may not be controlled. If the amount is more than 1.0 part by mass, the reaction rate may decrease, and the composition may yellow over time.

Further, in the present invention, in terms of promoting photocurability,
It is preferable to use (3) a photopolymerization initiator for the prepolymer to obtain a photocurable resin composition.

As the photopolymerization initiator (2) of the present invention, benzophenone, methyl orthobenzoyl benzoate and 4
Benzophenone-based photopolymerization initiators such as -benzoyl-4'-methyldiphenylsulfide, acetophenone, benzyldimethylketal, 2-hydroxy-2-methyl-1-phenylpropan-1-one and 2-methyl-1
An acetophenone-based photopolymerization initiator such as-[4- (methylthio) phenyl] -2-morpholinopropane-1 and a benzoin ether-based photopolymerization such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether are initiated. And thioxanthone acylphosphine oxides such as isopropylthioxanthone and diethylthioxanthone, benzyl, camphorquinone, anthraquinone and Michler's ketone. One or more of these can be used. Among these, in terms of yellowing resistance,
Benzoin ether photopolymerization initiators are preferred, and benzoin ethyl ether is more preferred.

The amount of the photopolymerization initiator used is from 0.001 to 1 based on 100 parts by mass of the total of polyene and polythiol.
0 parts by mass is preferable, and 0.05 to 1 part by mass is more preferable. If the amount is less than 0.001 part by mass, the curing speed may be slow. If the amount exceeds 10 parts by mass, the curing speed may be too fast, and the composition may yellow over time.

Further, in the present invention, it is preferable to use a coupling agent from the viewpoint of improving adhesiveness.

Examples of the coupling agent include a silane coupling agent, a titanate coupling agent, a zirconate coupling agent, and an organic aluminum coupling agent. Among these, a silane coupling agent is preferable from the viewpoint of adhesiveness.

Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane,
-(Β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ
-Chloropropyltrimethoxysilane, β- (3,4-
Epoxycyclohexyl) ethyltrimethoxysilane and vinyl-tris (β-methoxyethoxy) silane. Among them, vinyl-
Tris (β-methoxyethoxy) silane is preferred.

The amount of the silane coupling agent used is 0.0 to 100 parts by mass of the total of polyene and polythiol.
The amount is preferably from 1 to 2 parts by mass, more preferably from 0.1 to 1 part by mass. If the amount is less than 0.01 part by mass, the adhesiveness may be reduced. If the amount exceeds 2 parts by mass, the physical properties of the cured product may be reduced.

The photocurable resin composition of the present invention may contain, if necessary, an adhesion improver such as an organosilicon compound, an antioxidant, a polymerization inhibitor, a filler, a coloring agent, a thixotropic agent,
Various commonly used additives such as a curing accelerator, a plasticizer and a surfactant may be added.

The photocurable resin composition of the present invention undergoes addition polymerization of polyene and polythiol by light irradiation, and cures in a short time of several seconds to several minutes. As a light source, an ultrahigh-pressure, high-pressure, or low-pressure mercury lamp, ultraviolet light from a metal halide lamp, or the like is used.

The photocurable resin composition of the present invention is used as an adhesive for bonding optical elements. As a method for manufacturing a bonded optical element, for example, after applying an adhesive for an optical element to the bonding surface of one optical element, the bonding surface of the other optical element is overlapped on this bonding surface, and the adhesive is irradiated with light. And curing.

[0043]

EXAMPLES Examples and comparative examples of the present invention will be described below.

Experimental Example 1 A polyene and a polythiol shown in Table 1 were mixed so that the molar ratio of the carbon-carbon double bond in the polyene to the thiol group in the polythiol was 1: 1 and then stirred at 40 ° C. Then, a prepolymer was prepared. For the prepolymer, the amount of metal ions and the viscosity at a predetermined stirring time were evaluated. Table 1 shows the results.

(Materials used) Polyene: Unpurified diallyl maleate was added with a boiling point of 14%.
One obtained by distillation under reduced pressure at 0 to 180 ° C. (100 to 700 Pa) to remove metal ions. Polythiol α: a metal ion removed by the following method. To 100 g of unpurified tris-2-hydroxyethyl-isocyanurate-tris-β-mercaptopropionate, an aqueous solution of a chelating agent at 85 ° C. consisting of 25 g of ion-exchanged water and 0.025 g of a chelating agent (ethylenediaminetetraacetic acid) is added. In addition, the mixture was heated to 60 ° C. and stirred to generate a chelate compound, and allowed to stand still to remove the chelating agent aqueous solution as a supernatant. Then, hot water (ion-exchanged water) at 60 ° C. was further added, stirred and allowed to stand, and the chelating agent aqueous solution as a supernatant was removed. This operation was repeated several times. Photopolymerization initiator: Benzoin ethyl ether

(Evaluation Method) Viscosity: Measured using an E-type viscometer at a temperature of 25 ° C. Amount of metal ion: The amount of metal ion in polyene and polythiol before and after purification was measured, and the amount of metal ion in the prepolymer was calculated from the amount of polyene and polythiol used. It is shown by the total amount of sodium, iron, calcium, copper, magnesium and tin ions. For sodium, flame flame analysis (model: Hitachi Z-8230, polarized Zeeman atomic absorption spectrophotometer) was used, and iron, calcium, copper,
ICP analysis for magnesium and tin (Model:
It was measured using SEIKO ELECTRONICS SPS-1200A).

[0047]

[Table 1]

Experimental Example 2 The same procedure as in Experimental Example 1 was carried out except that a prepolymer was prepared at the temperatures shown in Table 2 and the viscosity was evaluated. Table 2 shows the results.

[0049]

[Table 2]

EXPERIMENTAL EXAMPLE 3 Experimental Example 1 was repeated except that the polyene and polythiol shown in Table 3 were mixed at the temperature shown in Table 3 to prepare a prepolymer.
The same was done. Table 3 shows the results.

(Materials used) Polyene: Unpurified triallyl isocyanurate is
Metal ions removed by chelating agent. Removal of metal ions was performed in the same manner as for polythiol α. Polythiol β: unpurified trimethylolpropane-tris-β-mercaptopropionate from which metal ions have been removed with a chelating agent. Removal of metal ions was performed in the same manner as for polythiol α.

[0052]

[Table 3]

Experimental Example 4 A polyene and a polythiol shown in Table 1 were mixed at a temperature shown in Table 4 until the viscosity became 500 cps.
A prepolymer was prepared in the same manner as in Experimental Example 1. 50 viscosity
After reaching 0 cps, 0.05 parts by mass of a reaction terminator was used with respect to 100 parts by mass of the total of polyene and polythiol, and the mixture was stirred at 60 ° C. for 60 minutes. The prepared prepolymer was checked for the presence of carbon-carbon double bonds and mercapto groups. Then, a total of 10 of polyene and polythiol
With respect to 0 parts by mass, 0.5 parts by mass of a photopolymerization initiator is used,
After stirring at 60 ° C. for 60 minutes, the mixture was cooled, and a photocurable resin composition was obtained using 0.5 parts by mass of a coupling agent with respect to 100 parts by mass of a total of polyene and polythiol. The obtained photocurable resin composition was evaluated for adhesive strength, destruction state, and yellowing. Table 4 shows the results.

(Materials used) Reaction terminator: N-nitrosophenyl / hydroxylamine ammonium salt Photopolymerization initiator: Benzoin ethyl ether Coupling agent: Vinyl-tris (β-methoxyethoxy) silane

(Evaluation method) Adhesive strength: Indicated by tensile shear adhesive strength, JIS K-6
It was measured according to 850. Under a condition of a temperature of 23 ° C. and a humidity of 50%, two glass sheets (dimensions: 12.5 mm × 25 mm × 1.2 mm) are laminated using the photocurable resin composition, and cured by irradiating ultraviolet rays. (UV irradiation dose is 6
000 mJ), a reinforcing plate (SPCC-D steel plate, 100 mm × 25 mm × 1.6 mm) was bonded to both surfaces of the glass, and the tensile shear bond strength was measured with a tensile tester. Breaking state: After measuring the adhesive strength, the breaking state of the specimen was observed and evaluated. Presence / absence of carbon-carbon double bond: After prepolymer was prepared by reacting polyene and polythiol, the amount of unreacted polythiol was titrated. The presence or absence of a carbon-carbon double bond was evaluated from the amount of polythiol. In addition, using IR,
The presence or absence of a carbon double bond was confirmed. Presence or absence of mercapto group: Confirmed by iodine titration. or,
The presence or absence of a mercapto group was confirmed using IR.

[0056]

[Table 4]

Experimental Example 5 The photocurable resin compositions shown in Table 5 were evaluated for yellowing. Table 5 shows the results. However, Experiment No. 5-1 is a commercially available polyene / polythiol-based photocurable resin composition containing polyene and polythiol (contains a large amount of a photopolymerization initiator and a reaction terminator).

(Evaluation Method) Yellowing: The photocurable resin composition was visually observed and evaluated.

[0059]

[Table 5]

Experimental Example 6 The photocurable resin composition of 4-1 was used as an adhesive for bonding lenses. The adhesive was applied to the surface of the concave lens, and the convex lens was superimposed on the applied surface, and defoaming and centering were performed while rubbing. Furthermore, temporary curing and main curing were performed using an ultraviolet lamp to produce a cemented lens. In this series of operations, workability was good and production of a cemented lens was easy. Further, the bonded portion did not turn yellow even after long-term use of this cemented lens.

EXPERIMENTAL EXAMPLE 7 The photocurable resin composition of 4-1 was used as an adhesive for joining the prisms. This adhesive was applied to the prism surface, another prism was superimposed on the applied surface, and bubble removal and positioning were performed while sliding. Furthermore, temporary curing and main curing were performed with an ultraviolet lamp to produce a bonded prism. In this series of operations, the workability was good and the manufacture of the cemented prism was easy. Further, the bonded portion did not turn yellow even after long-term use.

[0062]

According to the present invention, a photocurable resin composition having a low viscosity can be obtained. Accordingly, the operation of manufacturing the bonded optical element by bonding the optical elements is facilitated. 400 at 25 ° C
The photocurable resin composition can be stored with the low viscosity of not more than 00 mPa · s. Further, since the amount of a reaction terminator or a photopolymerization initiator used for the photocurable resin composition is reduced,
The benefits are extremely large because yellowing is less likely to occur, and product variability is reduced.

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Claims (6)

[Claims] 1. A photocurable resin comprising (1) a prepolymer having a carbon-carbon double bond and a mercapto group obtained by previously reacting a polyene and a polythiol, and (2) a photopolymerization initiator. A bonded optical element formed by bonding using a composition. 2. The prepolymer has a viscosity of 40,000 mPa.
A bonded optical element formed by bonding using the photocurable resin composition according to claim 1 having a value of s or less. 3. The method according to claim 1, wherein the metal ion in the prepolymer is 50 pp.
A bonded optical element which is bonded by using the photocurable resin composition according to claim 1 or less. 4. A bonded optical element formed by bonding using the photocurable resin composition according to claim 1, wherein the prepolymer further contains a reaction terminator. 5. The cemented optical element according to claim 1, wherein the optical element is a lens. 6. The optical element according to claim 1, wherein the optical element is a prism.
The bonded optical element according to claim 1.