JP3135108B2 - Adhesive for fixing optical parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical component, and more particularly to an adhesive for bonding and fixing an optical fiber.

[0002]

2. Description of the Related Art In recent years, with the rapid development of the information society,
Demands for optical fibers and photoelectric conversion elements are also increasing in the field of optical communication and home appliances. Especially for optical fibers, the bonding between the waveguide and the optical fiber was conventionally performed by a metal bonding method such as laser welding or solder bonding, but there were problems such as poor fixing accuracy and inapplicability to parts that dislike high temperature. . In recent years, resin-based adhesives have been released, but in general, a large amount of inorganic filler is added to reduce curing shrinkage, making it a hard and brittle material.Adhesive strength is weak, and cracks and There are problems such as peeling.

[0003]

SUMMARY OF THE INVENTION The present invention has been made as a result of intensive studies in order to solve the above-mentioned conventional problems, and could not be achieved by the conventional metal bonding method or resin-based adhesive. The present invention relates to an optical component fixing adhesive having good workability and high reliability.

[0004]

According to the present invention, the value of the coefficient of linear expansion (1 / ° C.) × Young's modulus (kgf / mm ² ) of the cured adhesive is 0.04 or less and the coefficient of linear expansion is 3 × 10 ^-5 (1 / ℃)
Less than or equal to 1000 (kgf / mm ² )
And the adhesive is (a) an epoxy resin, and (b) one molecule.
Compound having two or more hydroxyl groups in it, (c) cationic curing
An adhesive for fixing an optical component, comprising a catalyst and (d) an inorganic filler as essential components.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Assuming that the stress applied to the interface between a resin and an insert (insert, for example, an optical fiber) is σ, when the linear expansion coefficient of the insert is sufficiently smaller than that of the resin, σ = ∫α * Edt (α) : Linear expansion coefficient, E: Young's modulus,
t: temperature), and the linear expansion coefficient and the Young's modulus are not uniquely determined alone, but are determined by the product of the linear expansion coefficient and the Young's modulus. In the present invention, focusing on this fact and conducting intensive studies, the product of the linear expansion coefficient (1 / ° C.) and the Young's modulus (kgf / mm ² ) of the cured product of the adhesive is 0.04 or less and the linear expansion Coefficient is 3 × 10 ^-5 (1 / ° C.) or less and Young's modulus is 100
When it was 0 (kgf / mm ² ) or more , the stress was reduced, and it was found that cracks and peeling did not occur in the temperature cycle test, and that the adhesive strength after the temperature cycle test was extremely high.

[0006] linear expansion coefficient is more than ^{3 × 10 -5 (1 / ℃} ), the Young's modulus falls below the 1000 (kgf / mm ^2), if the linear expansion coefficient × Young's modulus was 0.04 or less Even under a thermal shock condition such as a temperature cycle, residual strain gradually accumulates in the resin or at the interface with the adherend, causing a problem. Also <br/>, tree fat used in the present invention, from the viewpoint of ease of critical alignment in the adhesion of the adhesive and optical components, the combination with the photocurable alone or thermoset that can positionally fixed in a short time possible epoxy resins, moreover a cationic curing system.
Further as a cationic curing system, it is more preferable that the high curing speed cycloaliphatic epoxy is contained more than 60% by weight fraction of the epoxy resin, as such alicyclic epoxy resins 3,4-epoxy Examples thereof include those obtained by oxidizing a double bond in a ring of a cycloalkene, represented by cyclohexylmethyl (3,4-epoxycyclohexane) carboxylate, with a peroxide and introducing an epoxide.

Further, this resin system may contain a compound having two or more hydroxyl groups in one molecule, more preferably a polyhydric alcohol, in terms of imparting flexibility to the resin and accelerating the curing speed. preferable. Examples of the polyhydric alcohol include hexanediol, neopentyl glycol, trimethylolpropane, glycerin and the like. However, there is no particular problem even if it has a phenolic hydroxyl group such as a phenol resin other than alcohol. The ratio of the polyhydric alcohol addition amount A to the epoxy resin addition amount B is A: B =
The ratio is preferably in the range of 5:95 to 50:50. If the amount of the polyhydric alcohol is too small, the cured product tends to be somewhat brittle or the curing is slow. If the amount is too large, poor curing occurs.

As a curing catalyst used in a cationic curing system, a triarylsulfonium salt is widely used as a photocationic curing catalyst, but other curing catalysts based on iodonium salts and diazonium salts are known to those skilled in the art. Things. Examples of the thermal cation curing catalyst include general protonic acids, Lewis acids, trialkyloxonium salts, carbonium salts, diazonium salts, alkylating agents, ammonium salts, sulfonium salts, and phosphonium salts. However, considering the easiness of alignment of the optical components, it is preferable to use a photocationic curing catalyst, but there is no problem even if a thermal cationic curing catalyst is used.

The filler used in the present adhesive is preferably an inorganic filler. Specifically, calcium carbonate, crystalline silica,
Fused silica, alumina, magnesia, clay, talc,
Ceramic powder, glass fiber, etc. are exemplified, but fused silica is preferred in consideration of the coefficient of linear expansion, and the amount of addition is 40% or more and 80% or more in the total weight of the adhesive.
The following is preferred. If it is less than 40%, the coefficient of linear expansion becomes too large, and if it is more than 80%, the fluidity is remarkably reduced, and the workability is reduced. In order to express better fluidity, 50% by weight fraction in all fused silica
The above is more preferably spherical fused silica. In the present invention, it is not necessary to add an elastomer, an antifoaming agent, a coupling agent, etc. for obtaining flexibility as required.

When the adhesive for fixing an optical component in the present invention is used, for example, for fixing a V-groove of an optical fiber, after positioning, apply the present adhesive with a dispenser or the like, and use ultraviolet light such as a high-pressure mercury lamp or a metal halide lamp. And cure and fix. In this case, it is advantageous to use thermal cation curing in combination with the case where light is blocked by shadows or when the film thickness is large.

[0011]

【Example】

(Example 1) 30% of alicyclic epoxy celloxide 2021 manufactured by Daicel Chemical Industries, 2% of 1,6-hexanediol, photocationic curing catalyst SP150 manufactured by Asahi Denka Kogyo
1.5%, fused spherical silica A having an average particle diameter of 6 microns and coarse particles of 70 microns or more cut, 56.5% of fused spherical silica A having an average particle diameter of 12 microns and coarse particles of 70 microns or more cut 0.0%, and kneaded with three rolls for 10 minutes to obtain an adhesive. The coefficient of linear expansion of this cured product was measured at a heating rate of 5 ° C./min using a thermomechanical analyzer, and the Young's modulus was measured at room temperature using Tensilon. The curing conditions are shown in Table 2. The adhesion was measured by preparing a glass test piece as shown in FIG. 1 and irradiating the test piece with light using a 5000 W high-pressure mercury lamp by the method shown in FIG. mi
n immediately after bonding in a tensile mode and at a lower limit of −40 ° C.
The change in adhesive force after 500 cycles of the temperature cycle of the upper limit of 85 ° C. was observed. For further confirmation, quartz 125
A single-mode optical fiber having a micron diameter was fixed in a V-groove and subjected to 500 temperature cycles under the same conditions as described above to check for defects. The results are shown in Tables 1 and 2.

[0012]

[Table 1] * 1: Alicyclic epoxy resin manufactured by Daicel Chemical Industries * 2: Alicyclic epoxy resin manufactured by Asahi Denka Kogyo * 3: Bisphenol A type epoxy resin with an epoxy equivalent of 185 * 4: Hydrogenated bisphenol A manufactured by Nippon Rika * 5: Phenol novolak manufactured by Sumitomo Durez * 6: Photocationic curing catalyst manufactured by Asahi Denka Kogyo * 7: Thermal cation curing catalyst manufactured by Asahi Denka Kogyo

[0013]

[Table 2]

(Examples 2 to 4 and Comparative Examples 1 and 2) All the formulations were carried out as shown in Table 1, and the evaluation method was carried out in the same manner as in Example 1. The results are summarized in Table 2. (Comparative Examples 3 and 4) Comparative Examples 3 and 4 were also made into a material according to the composition shown in Table 1 and evaluated. However, as shown in Table 2, the viscosity was too high or the curability was poor.

[0015]

The adhesive for fixing an optical component according to the present invention is an adhesive excellent in workability and high reliability which has never existed in the past, particularly excellent in temperature cycle property.

[Brief description of the drawings]

FIG. 1 is a side view and a top view of a glass test piece.

FIG. 2 shows a bonding method. The amount of ultraviolet light used after passing through the glass plate was actually measured to determine curing conditions.

[Explanation of symbols]

 1 Test piece shown in FIG. 1 2 Adhesive 3 50 mm × 50 mm × 3 mm thick glass plate 4 UV irradiation direction 5 Adhesion force measurement direction 6 Tensilon chuck mounting part

Claims (4)

(57) [Claims] 1. An adhesive for bonding and fixing an optical component such as an optical fiber, wherein a value of a coefficient of linear expansion (1 / ° C.) × Young's modulus (kgf / mm ² ) of the cured product of the adhesive is 0.04 or less and The coefficient of linear expansion is 3 × 10 ⁻⁵ (1 / ° C.) or less and
The adhesive rate is 1000 (kgf / mm ² ) or more,
Are (a) an epoxy resin, and (b) two hydroxyl groups in one molecule.
And (c) a cationic curing catalyst, and
(D) An adhesive for fixing an optical component, wherein an inorganic filler is essential . 2. The inorganic filler of the adhesive component (d) is fused silica, and its content is 40% by weight or more (hereinafter simply abbreviated as%) in the adhesive in a weight fraction of 80% or more.
% Or less. Wherein the optical component fixing adhesive according to claim 1 or 50% is spherical fused silica in a weight fraction of fused silica component (d) in claim 2. 4. The alicyclic epoxy resin accounts for at least 60% by weight of the epoxy resin of the component (a), and the compound having two or more hydroxyl groups in one molecule of the component (b) is a polyhydric alcohol. A: B = 5: 95, where A is the added weight of (b) and B is the added weight of the epoxy resin.
The adhesive for fixing an optical component according to claim 1, wherein the curing catalyst of the component (c) is a photocationic curing catalyst.