JPH10102026A - Ultraviolet-curable adhesive for sealing hollow package of optical and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject adhesive having a remarkably excellent heat- resistance, developing a low stress and quickly curable without heating by compounding an epoxy resin, a hydroxyl-containing compound, a compound having a polybutadiene skeleton and a photo-cationic curing initiator. SOLUTION: This adhesive contains (A) an epoxy resin having >=2 epoxy groups, (B) a compound having >=2 hydroxyl groups, (C) a compound having a polybutadiene skeleton and (D) a photo-cationic curing initiator as essential components. The addition amount of the component A is preferably 50-90wt.% and not less than 10% of the total component is preferably a hydrogenated bisphenol A epoxy resin having an epoxy equivalent of 100-2,000. The component B is preferably a polyhydric alcohol such as polyethylene glycol and the hydroxyl equivalent of the component B is preferably <=15,000. The molecular weight of the component C is preferably <=10,000. The component D is preferably selected from triaryl sulfonium salt and diallyl iodonium salt.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet-curable adhesive made of a light-transmitting material, such as quartz glass, for hermetically sealing a hollow optical or electronic device package.

[0002]

2. Description of the Related Art It is well known that optical and electronic devices (hereinafter simply referred to as devices) are generally used in a state of being enclosed in a resin package because they are greatly affected by changes in ambient temperature and humidity. It was done. Package methods are broadly classified into resin sealing and hermetic sealing. Conventionally, airtight sealing has been mainly can-sealing using metal, but in recent years, the device has been fixed in a hollow package such as resin or ceramic, and the upper part of the case is made of a light-transmitting material, for example, quartz glass. There is an increasing number of systems in which a lid such as a synthetic resin plate or a ceramic plate is fixed using an adhesive. Although thermosetting adhesives are widely used for this adhesive, there is a problem that high temperatures cannot be used for sealing optical elements, for example, communication modules, whose demand is expected to increase in the future. In addition, ultraviolet curable adhesives have been required from the viewpoint of production efficiency.

In general, in a reliability test of a device, a temperature cycle test and a moisture resistance test are important. However, in an acrylate resin-based adhesive used as an ultraviolet curable adhesive for hermetic sealing, Epoxy acrylate resin adhesives have problems such as large shrinkage of the adhesive at the time of curing, large stress is applied to the adherend at the time of curing, the cured resin is hard, and the lid peels off at the time of curing and temperature cycle test. . Further, when a soft acrylate-based adhesive such as urethane acrylate resin is used to reduce the stress, there is a problem that the moisture resistance is greatly reduced.

[0004] It is already known among those skilled in the art that an epoxy resin is used as a resin composition of an adhesive which has a small shrinkage upon curing and has excellent moisture resistance. In the case of an adhesive composed of only an epoxy resin and an initiator, the adhesive has a high crosslinking density, and is very hard and brittle. Therefore, in the temperature cycle test, the bonded portion between the case and the lid is distorted, cracks occur, and the lid peels off. Therefore, in order to reduce the stress, it is necessary to lower the crosslinking density to some extent. JP-A-60-199024
Discloses that adding a polydiene-based epoxy compound imparts flexibility. However, when the present inventors examined the polybutadiene-based epoxy compound for hermetic sealing of a hollow package for a device, it was found that curing with a photocationic curing initiator (that is, cationic curing was a polymerization curing type) had a sufficiently low level. The stress effect was not obtained, and it was presumed that, unlike the anion curing using a curing agent, the epoxy group worked as bifunctional, so that the crosslink density did not decrease as in the case of the anion curing. Therefore, the present inventors have conducted intensive studies to further reduce the crosslink density. As a result, it was found that the combined use of a compound having two or more hydroxyl groups in one molecule and a compound having a polybutadiene skeleton can achieve excellent low stress. This led to the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention is a transparent or translucent glass plate which is an adhesive used for hermetically sealing a hollow package for a device, and has remarkably excellent moisture resistance and low stress. Fast curing without heating,
It is an object of the present invention to provide an ultraviolet-curable adhesive for sealing optical and electronic device hollow packages.

[0006]

The present invention provides (a) an epoxy resin having two or more epoxy groups in one molecule,
(B) a compound having two or more hydroxyl groups in one molecule,
(C) a compound having a polybutadiene skeleton in a molecule thereof; and (d) an ultraviolet-curable adhesive for encapsulating a hollow package of a light or electronic device, comprising a photocationic curing initiator as an essential component. is there.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxy resin having two or more epoxy groups in one molecule, which is an essential component of the adhesive of the present invention, is a bisphenol A epoxy resin, a brominated bisphenol A epoxy resin, a bisphenol F epoxy resin. Epoxy resin, hydrogenated bisphenol A type epoxy resin, alicyclic epoxy resin, phenol novolak type epoxy resin, orthocresol novolak type epoxy resin, etc. can be exemplified, but bisphenol A is preferred in terms of moisture resistance, curing speed, heat resistance and the like. Type epoxy resin, hydrogenated bisphenol A type epoxy resin and alicyclic epoxy resin are more preferable, and the addition amount of component (a) is 50% by weight or more,
0% by weight or less is preferable in terms of balance of properties such as curability, flexibility, and moisture resistance. Further, in order to sufficiently obtain the flexibility of the cured product, hydrogenated bisphenol A should be at least 10% by weight.
It is more preferably a type epoxy resin, and the epoxy equivalent is preferably 100 or more and 2000 or less. If the epoxy equivalent is 100 or less, the crosslink density becomes high, and the cured product may become brittle. If the epoxy equivalent is more than 2,000, the curability will be poor, and a problem will occur that the resin will not lose its tack even after being irradiated with ultraviolet rays for a long time. For the present adhesive, one kind of epoxy resin having two or more epoxy groups in one molecule or a mixture of two or more kinds thereof can be used.

The adhesive is characterized by adding as essential components a compound (b) having two or more hydroxyl groups in one molecule and a compound (c) having a polybutadiene skeleton in the molecule. Examples thereof include hexanediol, neopentyl glycol, trimethylolpropane, glycerin, hydrogenated bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc. as compounds having two or more hydroxyl groups in one molecule. it can. Moreover, there is no problem even if it is a compound having two or more hydroxyl groups in one molecule having a phenolic hydroxyl group represented by bisphenol A or phenol novolak resin. Compounds having a polybutadiene skeleton in the molecule, which is an essential component of the adhesive, include terminal hydroxyl group polybutadiene, terminal isocyanate group polybutadiene, terminal carboxylic acid group polybutadiene, terminal epoxy group polybutadiene, pendant epoxy-modified polybutadiene, and internal olefin epoxy. Polybutadiene, maleic anhydride-modified polybutadiene, half-esterified polybutadiene having a carboxyl residue, acrylated polybutadiene having a carboxyl residue, and phenolated polybutadiene. (B) If either one of the two components is not added to the adhesive, the adhesive will not be reduced in stress, and if used in a hollow optical or electronic device package, the lid may be subjected to a temperature cycle test. The material will peel off. further,
The compound having two or more hydroxyl groups in one molecule used in the present adhesive is preferably a polyhydric alcohol in consideration of cation curing reactivity. Polyhydric alcohols can easily release protons, so that cationic curing reactivity can be increased. Further, the hydroxyl equivalent of the compound having two or more hydroxyl groups in one molecule is more preferably 15,000 or less. If it is larger than 15,000, the viscosity of the adhesive increases and the workability may decrease. Further, the compound having a polybutadiene skeleton in the molecule, which is an essential component of the present adhesive, preferably has a molecular weight of 10,000 or less, and if it exceeds this range, the workability may be reduced. Further, a compound having a functional group capable of reacting with an epoxy group or a hydroxyl group in the molecule is more preferable. In this case, the compound having a polybutadiene skeleton in the molecule is taken into the crosslinked structure during curing, and even if the amount added to the adhesive is small,
The effect of reducing the stress can be sufficiently obtained. In the present adhesive, one kind of the above-mentioned compound having two or more hydroxyl groups in one molecule and one kind of the compound having a polybutadiene skeleton in one molecule, or a mixture of two or more kinds can be used.

The cationic cationic curing initiator, which is an essential component of the present adhesive, is at least one member selected from the group consisting of triarylsulfonium salts and diallyliodonium salts, in that curing proceeds even after the ultraviolet ray irradiation is stopped. More preferably, it is selected.

The adhesive of the present invention does not need to add additives such as an antifoaming agent, a coupling agent, a diluent, a thixotropic agent and a filler as required.

In the case where the hollow case is hermetically sealed with a transparent glass plate lid, for example, the adhesive is applied with a dispenser or the like, and the ultraviolet-curable adhesive in the present invention is applied. Curing and fixing using ultraviolet light such as a high-pressure mercury lamp and a metal halide lamp.

[0012]

【Example】

(Example 1) 50% by weight of alicyclic epoxy celloxide 2021 manufactured by Daicel Chemical Industries, Ltd., hydrogenated bisphenol A type epoxy EP40 manufactured by Asahi Denka Kogyo KK
80 15% by weight, 8% by weight of 1,6-hexanediol, 13% by weight of polyethylene glycol having a molecular weight of 400, 5% by weight of epoxy-modified polybutadiene PB3600 manufactured by Daicel Chemical Industries, Ltd., 5% by weight of polybutadiene having terminal epoxy group manufactured by Idemitsu Petrochemical Co., Ltd. Poly bd R-
45 EPT 5% by weight and Asahi Denka Kogyo Co., Ltd. photoinitiator SP150 4% by weight were blended, and heated and melt-mixed to obtain an adhesive.

(Examples 2 to 5) The formulations of Examples 2 to 5 were carried out in the same manner as in Example 1 according to Table 1.

[0014]

[Table 1]

* 1: Alicyclic epoxy resin manufactured by Daicel Chemical Industries, Ltd. * 2: Hydrogenated bisphenol A type epoxy resin manufactured by Asahi Denka Kogyo Co., Ltd. * 3: Bisphenol A manufactured by Yuka Shell Epoxy Co., Ltd.
Type epoxy resin * 4: Bisphenol A manufactured by Yuka Shell Epoxy Co., Ltd.
Type epoxy resin * 5: Orthocresol novolak type epoxy resin having a softening point of 65 ° C and an epoxy equivalent of 200 * 6: Phenol novolak manufactured by Sumitomo Durez Co., Ltd. * 7: Polyethylene glycol having an average molecular weight of 400 * 8: Daicel Chemical Industries, Ltd. Epoxy-modified polybutadiene * 9: Idemitsu Petrochemical Co., Ltd. Terminal epoxy group polybutadiene * 10: Asahi Denka Kogyo Co., Ltd. photoinitiator

(Comparative Examples 1 to 5) The formulations of Comparative Examples 1 to 5 were carried out in the same manner as in Example 1 according to Table 2.

[0017]

[Table 2]

* 1: Aromatic urethane acrylate resin manufactured by Daicel U.S.C. Co., Ltd. * 2: Vinyl ester resin manufactured by Showa Polymer Co., Ltd. * 3: Photoinitiator manufactured by Ciba-Geigy Japan

The adhesive was evaluated by applying it to the simulated hollow package shown in FIG. 1, sealing hermetically with a glass lid, irradiating ultraviolet rays (using a 5000 W high-pressure mercury lamp), and fixing the lid. The package was subjected to a temperature cycle test (-40
℃ to 85 ℃) and high temperature and high humidity storage test (85 ℃, 85
%). In these tests, the defect was judged by attaching the side surface of the lid to the cutout portion of the package with a push-pull gauge and measuring the adhesive strength. The results are summarized in Tables 3 and 4.

[0020]

[Table 3]

* 1: Temperature cycle test condition Upper limit: 85
° C, lower limit -40 ° C, 30 minutes each * 2: High temperature and high humidity test conditions 85 ° C, 85%

[0022]

[Table 4]

* 1: Temperature cycle test condition upper limit: 85
° C, lower limit -40 ° C, 30 minutes each * 2: High temperature and high humidity test conditions 85 ° C, 85%

[0024]

The ultraviolet-curable adhesive of the present invention is an adhesive having excellent moisture resistance, flexibility and low stress.

[Brief description of the drawings]

FIG. 1 is a perspective view, a top view, a side view, and an AB sectional view of a simulated hollow package made of ceramic.

FIG. 2 is a perspective view, a top view, and a side view of a glass lid for a simulated hollow package.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Simulated hollow package made of ceramic 2 Glue 3 Notch 4 Glass lid for simulated hollow package

Claims (8)

[Claims] 1. An epoxy resin having two or more epoxy groups in one molecule, (b) a compound having two or more hydroxyl groups in one molecule, and (c) a compound having a polybutadiene skeleton in one molecule. And (d) an ultraviolet curable adhesive for sealing a hollow package of a light or electronic device, comprising a cationic photocuring initiator as an essential component. 2. A bisphenol A type epoxy resin having an epoxy equivalent of 100 or more and 2000 or less, wherein the epoxy resin having two or more epoxy groups in one molecule of the component (a) is:
An epoxy resin selected from at least one selected from the group consisting of hydrogenated bisphenol A type epoxy resin and alicyclic epoxy, and wherein this component (a) is 50% by weight of all components
The content is at least 90% by weight or less.
The ultraviolet curable adhesive for sealing a hollow package of a light or electronic device according to the above. 3. An epoxy resin having two or more epoxy groups in one molecule of the component (a), wherein 10
2. The ultraviolet-curable adhesive for sealing optical and electronic device hollow packages according to claim 1, wherein the weight percent or more is a hydrogenated bisphenol A type epoxy resin having an epoxy equivalent of 100 or more and 2000 or less. 4. The light and ultraviolet ray for sealing electronic device hollow package according to claim 1, wherein the compound having two or more hydroxyl groups in one molecule of the component (b) has a hydroxyl equivalent of 15,000 or less. Curable adhesive. 5. The ultraviolet curing for sealing a hollow package of an optical or electronic device according to claim 1, wherein the compound having two or more hydroxyl groups in one molecule of the component (b) is a polyhydric alcohol. Mold adhesive. 6. The ultraviolet curable adhesive for sealing optical and electronic device hollow packages according to claim 1, wherein the molecular weight of the compound having a polybutadiene skeleton in the molecule of the component (c) is 10,000 or less. 7. The compound according to claim 1, wherein the compound having a polybutadiene skeleton in the molecule of the component (c) has a functional group capable of reacting with one or both of an epoxy group and a hydroxyl group in the molecule. Item 4. An ultraviolet curable adhesive for sealing a hollow package of an optical or electronic device according to Item 1. 8. The ultraviolet curable type for sealing optical and electronic device hollow packages according to claim 1, wherein the cationic photocuring initiator of the component (a) is a triarylsulfonium salt and / or a diaryliodonium salt. adhesive.