JP2676047B2 - UV curable precision adhesive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a cationic polymerization type ultraviolet curable precision adhesive having high reactivity and having a low curing shrinkage and a low linear expansion coefficient.

[Conventional technology]

A cationic polymerization type UV curable resin using an epoxy base resin has low reactivity and therefore requires a large amount of UV energy during curing. Therefore, there are drawbacks that a high-ultraviolet energy irradiation device is required and that irradiation time is long. Further, when a large amount of inorganic powder is filled in order to achieve a low curing shrinkage and a low linear expansion, there is a drawback that the reactivity becomes extremely low.

As a method for improving the low reaction of such a cationic UV curable resin, a method using an alicyclic epoxy as a base resin or a diluent is known. However, it is slower than the reaction rate of the radical UV curable resin. In addition, the types of alicyclic epoxies available are limited, and it is difficult to mix them to satisfy practical performance. On the other hand, if compounded so as to satisfy practical performance, there is a drawback that the reactivity is lowered, and it is difficult to achieve both reactivity and practical performance at the same time. For example, if an alicyclic epoxy that is available is blended so as not to reduce the reactivity, it is relatively brittle and does not have elongation, which is not practically sufficient.

[Problems to be solved by the invention]

To improve this, if a general softening agent is added for the purpose of imparting flexibility, there is a drawback that the reactivity is lowered. Further, in order to realize a precision adhesive having a low curing shrinkage and a low linear expansion coefficient, when a large amount of inorganic powder is filled, the reactivity is further lowered, and a practical compound cannot be prepared. there were.

An object of the present invention is to provide a UV-curable precision adhesive in which the reactivity of a cationic UV-curable resin composition using an epoxy base resin and an inorganic powder filler is improved.

[Means for solving the problem]

Briefly describing the present invention, the cationic UV-curable precision adhesive of the present invention is composed of 50 to 300 parts by weight of an inorganic powder filler and a cationic photopolymerization initiator with respect to 100 parts by weight of an epoxy-based resin. It is characterized in that the resin composition contains 3 to 20 parts by weight of an intramolecular epoxy-modified polybutadiene.

The cationic UV-curable precision adhesive of the present invention contains an intramolecular epoxy-modified polybutadiene, so even if the epoxy-based resin is filled with a large amount of inorganic powder,
It is characterized by high reactivity and sufficient practical performance. Conventional cationic UV-curable adhesives or cationic UV-curable precision adhesives filled with a large amount of inorganic fillers have low reactivity and are not practical.

Examples of the epoxy-based resin used in the present invention include bisphenol A-based epoxy resin, glycidyl ester-based epoxy resin, epoxy resin containing fluorine or bromine, modified products thereof, or other special epoxy resins, or And the like can be used. Further, as alicyclic epoxy resin, 3,4-epoxycyclohexyl-3,4-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta -Dioxane, bis (3,4-epoxycyclohexyl) adipate, etc., or modified products thereof, or a mixture thereof can be used.

The intramolecular epoxy-modified polybutadiene used in the present invention is one having an epoxy group having the following structure in the main chain.

For example, Poly bdR-45 EPI (epoxy equivalent 200, manufactured by Idemitsu Petrochemical Co., Ltd.) is available, but other intramolecular epoxy-modified polybutadiene can also be used.

An appropriate amount of the intramolecular epoxy-modified polybutadiene added is 3 to 20 parts by weight. If it is less than 3 parts by weight, the reactivity is not improved. On the other hand, if the amount exceeds 20 parts by weight, the properties of the cured product deteriorate, especially the curing shrinkage rate and linear expansion rate increase.

As the inorganic powder filler used in the present invention, it is suitable to use cordierite powder, talc powder, silica fine powder or a mixed powder thereof, but in addition thereto, kaolin, β-spodumene, β- Powders such as eucrypt, sericite, machinable ceramic powder, and mica can be used. In addition, since the viscosity can be freely adjusted by using Aerosil fine powder as the silica-based fine powder, an adhesive having an appropriate viscosity can be easily prepared according to the working situation.

As the cationic photopolymerization initiator used in the present invention, a commercially available cationic photoinitiator diazonium salt, halonium salt, sulfonium salt, or the like can be used.

Further, if necessary, a diluent, a pigment or the like can be added.

[Function] When the intramolecular epoxy-modified polybutadiene is added, the reactivity of the cationic UV-curable resin composition using the epoxy-based resin having low reactivity with UV rays can be improved.

〔Example〕

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited thereto.

Examples 1 to 4 Cationic UV curable resin compositions were prepared using the compounding components shown in Table 1, and photoreactivity (surface curing time, adhesive fixing time), adhesive strength, curing shrinkage ratio, linear expansion. The rate, water-resistant adhesiveness, etc. were evaluated.

Evaluation method of photoreactivity: An adhesive is applied to a slide glass of 76 × 26 mm as shown in FIG. 1, and a small glass piece of 7 × 13 mm is attached with an adhesive resin. Then, a predetermined amount of ultraviolet light was irradiated and the curability was observed. The surface hardening time was defined as the time when the adhesive was rubbed with a cotton swab and the cotton was not adhered. In addition, the adhesive fixing time was evaluated as the time at which the shearing force of about 3 kgf was applied to the small glass pieces so that the small pieces did not become misaligned. That is, FIG. 1 is a view showing the shape of the photoreactivity evaluation sample, FIG. 1-1 is a plan view, and FIG. 1-2 is a side view. Further, in each drawing, the two samples on the left side are for surface curability evaluation, and the three samples on the right side are for adhesive fixation evaluation.

Evaluation method of adhesive strength: Laminated adhesive pieces as shown in FIG. 2 were prepared (adhesive curing conditions were about 10 mW / cm ² metal halide lamp, irradiation for 5 minutes). For the measurement, put an adhesive piece in the sample holder as shown in FIG.
Compression was performed by a compression plate at a speed of 5 mm / min, and shear adhesive strength was measured. That is, FIG. 2 is a diagram showing an evaluation method of adhesive strength, and FIG. 2-1 is a schematic sectional view of the whole, and FIG.
FIG. 2 shows a test piece.

Evaluation method of curing shrinkage: The density before and after curing was measured to calculate the curing shrinkage.

Evaluation method of linear expansion coefficient: Measured by a thermomechanical analyzer.

Evaluation method of water resistant adhesion: 76 × 26 mm as shown in FIG.
A sample was prepared by fixing a small glass piece of 7 × 13 mm on a slide glass with an adhesive. After boiling this sample for 10 hours, peeling of the adhesive interface and generation of bubbles were observed to evaluate the water resistance. That is, FIG. 3 is a view showing the shape of a sample for evaluation of water-resistant adhesiveness, FIG. 3-1 is a plan view, and FIG. 3-2 is a side view.

 Table 1 shows the obtained results.

Note) Ep-828: Yuka Shell Co., Ltd. bisphenol type epoxy resin ERL-4221: UCC alicyclic epoxy resin ERL-4234: UCC alicyclic epoxy resin R-45 EPI: Idemitsu Petrochemical epoxy modified polybutadiene ERL-4206: UCC alicyclic epoxy resin diluent sp-170: Asahi Denka Co., Ltd. cationic photopolymerization initiator A-187: Nippon Yunika epoxy silane coupling agent [photocurable] using metal halide lamp, ◎: adhesive fixing, surface Curing (tack free), ○: Adhesive fixation, surface uncured, △: Adhesion fixation insufficient, surface uncured, ×: Adhesion unfixed, surface uncured [Adhesive strength] BK-7 glass adhesive, shear adhesive strength [Water resistance Properties] Adhesive piece of glass slide, after boiling for 10 hours,
◎: Peeling, no bubbles, ○: Very slight bubbles, peeling occurred,
Δ: Partial peeling, bubble generation, ×: Complete peeling Comparative Examples 1 to 3 Cationic UV curable resin compositions were prepared using the compounding components shown in Table 2, and photoreactivity (surface curing time, adhesion) (Fixing time), adhesive strength, cure shrinkage, linear expansion coefficient, water resistant adhesiveness, etc. were evaluated.

 Table 2 shows the obtained results.

[Effects of the Invention] As described above, the ultraviolet curable precision adhesive containing the epoxy resin of the present invention as a base resin, filled with an inorganic powder, and containing an intramolecular epoxy modified polybutadiene is reactive. Of high radical type UV curable resin composition, its reactivity is so high that it has no color, and it has sufficient practical performance such as adhesiveness and water resistance, and has a small curing shrinkage and linear expansion coefficient. have. From these facts, when the ultraviolet-curable precision adhesive of the present invention is applied to precision parts, for example, assembling of small optical parts and electronic parts, the surface for oxygen inhibition which is a drawback of the radical-type ultraviolet-curable resin composition. It is possible to realize a joining / adhesive fixing part that has no uncured, high reactivity, and good practical performance, and its effect is extremely useful, and its value in the industry is high.

[Brief description of the drawings]

FIG. 1 is a diagram showing the shape of a photoreactive evaluation sample, wherein FIG. 1-1 is a plan view, FIG. 1-2 is a side view, and FIG.
FIG. 2 is a view showing an adhesive strength evaluation method, FIG. 2-1 is a schematic sectional view of the whole, FIG. 2-2 is a view showing a test piece, and FIG. 3 is a shape of a sample for water-resistant adhesion evaluation. FIG. 3-1 is a plan view and FIG. 3-2 is a side view.

Claims (1)

(57) [Claims] 1. A resin composition comprising 50 to 300 parts by weight of an inorganic powder filler and a cationic photopolymerization initiator, based on 100 parts by weight of an epoxy base resin, and 3 to 20 parts by weight of an intramolecular epoxy modified polybutadiene. A UV-curable precision adhesive characterized by containing parts.