JPS6028403A - Photo-curable composition - Google Patents

Abstract

PURPOSE:To provide the titled composition curable with ultraviolet radiation, and giving a cured material having excellent electrical insulation, thermal conductivity and transparency, by dispersing boron nitride powder or diamond powder, etc. in a monomer or an oligomer, and adding a photo-sensitizer to the dispersion. CONSTITUTION:The objective composition is obtained by mixing or dispersing (A) boron nitride powder, diamond powder and/or alpha-alumina single crystal powder having particle diameter of preferably 0.5-100mu in (B) a monomer (e.g. vinyl acetate, diallyl phthalate, etc.) and/or an oligomer [e.g. epoxy (meth)acrylate having a molecular weight of 200-3,000], and adding (C) a photo-sensitizer (e.g. benzoin) to the dispersion. The amount of the component A is preferably 30- 80pts.wt. per 100pts.wt. of the component B. USE:An adhesive, a coating agent, etc.

Description

Detailed Description of the Invention The present invention provides a composition comprising boron nitride powder bundle, diamond powder or alpha alumina single crystal powder dispersed in a monomer and/or oligomer, and a photosensitizer further added thereto. It is cured by ultraviolet irradiation and can be used for coatings, adhesives, etc. with excellent electrical insulation and thermal conductivity.

With the recent development of ICs, adhesives and paints that have electrical insulation properties and thermal conductivity are required for bonding and painting electronic parts.

Furthermore, in order to shorten the work process and save labor, the curing time of these adhesives and paints has been shortened, so it has become necessary for these adhesives and paints to be photocurable. It has become.

Currently, adhesives have electrical insulation and thermal conductivity.

Thermosetting compositions in which, for example, polycrystalline alumina powder is dispersed in epoxy resin are known as paints, but these types of adhesives and paints do not have sufficiently satisfactory thermal conductivity. In addition, since the composition is cured by heating, there is a drawback in that workability is poor.

The present inventors have used boron nitride powder, diamond powder, or alpha alumina single crystal powder as adhesive and coating compositions that have electrical insulation and thermal conductivity and are photocurable from the viewpoint of productivity. It has been found that a composition containing a photosensitizer dispersed in a monomer and/or oligomer and to which a photosensitizer is added is effective.

As mentioned above, adhesive layers or painted surfaces are generally cured by heating, but in some fields where more rapid curing is required, such as computer assembly, ultraviolet curing methods are used in some areas. For hardening,
There are many restrictions on the compounding agents, and in particular when non-transparent or weakly translucent fillers are used, ultraviolet light does not penetrate deep into the filler, making it impossible to cure with ultraviolet light. Therefore, at present, the ultraviolet curing method is not used much. - Here, the present inventors disperse highly transparent nitrided boron powder bundles, diamond powder, or alpha alumina single crystal powder as fillers in monomers and/or oligomers, and then photosensitize the monomers and/or oligomers. It has been found that by adding an agent, a cured product can be cured by ultraviolet rays and has excellent electrical insulation and thermal conductivity.

This makes it possible to bond and paint with electrical insulation and thermal conductivity in a short period of time.

To carry out the invention, a boron nitride powder bundle, diamond powder or alpha alumina single crystal powder is well dispersed in a monomer or oligomer or a mixture of monomer and oligomer, and a photosensitizer is added thereto. to obtain a composition. The particle size of the boron nitride powder bundle, diamond powder or alpha alumina single crystal powder is preferably from 0.5 to 100 microns. As the boron nitride powder bundle, either cubic system or hexagonal system may be used. The diamond powder may be either natural or synthetic diamond; engineered type crystal and type II crystal are used as the natural diamond powder, and type II crystal is used as the synthetic diamond powder. Further, as the alpha alumina single crystal powder, for example, Showlite, Alfit (registered trademark, manufactured by Showa Denko K.K.), etc. can be used. These boron nitride powder bundles, diamond powder, and alpha alumina single crystal powder may be used in combination.

The present invention is characterized in that nitriding is performed by blending a boron powder bundle, diamond powder, or single crystal of alpha alumina with the monomer and/or oligomer, and if other inorganic powders other than these are blended, in some cases. However, there are disadvantages in that the photocurability is insufficient, and in some cases, the electrical insulation and thermal conductivity are insufficient. For example, if a composition in which thermally conductive silicon carbide powder, graphite powder, metal powder, etc. is mixed with a monomer and/or oligomer and a photosensitizer is added thereto is irradiated with ultraviolet rays, only the surface will be hardened. It has the disadvantage that it does not harden to the inside. In addition, in the case of compositions in which glass powder, silicon oxide powder, etc. are dispersed in monomers and/or oligomers, and a photosensitizer is added thereto, the inside is cured by ultraviolet irradiation, but on the other hand, the heat of the cured product It has the disadvantage of extremely low conductivity.

The monomers and oligomers used in the present invention include the following.

(1) Photopolymerizable vinyl monomers vinyl esters (vinyl acetate, vinyl propionate, vinyl 08-12 branched fatty acids, etc.), acrylic esters (acrylic acid alkyl esters, acrylic glycidyl, diethylene glycol diacrylate, trimethylolpropane trichloride, etc.) acrylate, pentaerythritol tetraacrylate, etc.), methacrylic acid esters (alkyl methacrylate, glycidyl methacrylate, diethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, etc.), aromatic unsaturated hydrocarbons (styrene , alkylstyrene, divinylbenzene, etc.), chlorine-containing unsaturated compounds (
chlorostyrene, chloroacrylic acid ester, etc.), fluorine-containing unsaturated compounds (fluorostyrene, fluoroalkyl acrylate, fluoroalkyl methacrylate, etc.), and mixtures thereof.

(2) A monomer that can undergo a photoaddition reaction A polymer is produced by a photoaddition reaction between an unsaturated compound and a mercaptan. In addition to the vinyl monomers mentioned above, the unsaturated compounds include polyvalent allyl compounds (diallyl phthalate, triallyl isocyanate, etc.). (nurate), and a compound having at least two cycloacetal groups in one molecule (diarylidenepentaerythritol, etc.) is used. Mercaptans include trimethylolpropane trithiopropionate, pentaerythritol tetrathioglycole)
- Polyvalent thiols such as dipentaerythritol hexathioglycolate are used.

(3) Oligomer A photocurable oligomer with a molecular weight of 200 to 300o is used, and typical examples include epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, urethane (meth)acrylate, Examples include silicone (meth)acrylate.

The above (1), (2) and (3) may be used in combination.

The amount of boron nitride powder, diamond powder or alpha alumina single crystal powder used is 10 to 90 parts by weight, preferably 3 to 80 parts by weight, per 10 parts by weight of monomer and/or oligomer. If the amount of boron nitride powder, sub-diamond powder or alpha alumina single crystal powder used is less than 10 parts by weight, the thermal conductivity of the cured product will be insufficient; on the other hand, if the amount used is more than 90 parts by weight. The strength of the cured product is insufficient.

As the photosensitizer, benzyl, benzoin, benzoin methyl ether, benzoin isopropyl ether, thioxanthone, azobisisobutyronitrile, 2-hydroxypropiophenone, etc. are used. In addition, for photocuring of epoxy compounds, onium salts (e.g. dimethylphenylsulfonium hexafluorophosphate,
．． 4'-Dimethyldiphenyliodonium hexafluoroarsenate etc.

The amount of these photosensitizers added is 0.01 to 5% by weight based on the monomer and/or oligomer. If the amount added is less than this, curing will be incomplete, and if the amount added is more than this, coloring will occur. This causes inconvenience.

It is also possible to add various additives to the composition according to the present invention as long as the physical properties are not impaired. For example, diluents such as leveling agents, ultraviolet absorbers, water repellents, and solvents can be used.

The photocurable composition of the present invention has excellent electrical insulation, heat conductivity, and translucency, so it can be used for adhesion of electronic parts, coating, etc.
It is also useful for manufacturing cast products.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 100 g of cubic boron nitride powder with a particle size of 50 microns was well dispersed in a mixture consisting of 40 g of methyl methacrylate, Log trimethylolpropane triacrylate, and 0.5 g of benzoin propyl ether, and then defosolated. Width 3cm.

Pour into a mold with a length of 5 mm and a depth of 0.3 cm, and heat at 20 W.
Ultraviolet rays were irradiated for 30 seconds using a high-pressure mercury lamp of / cm. After it was completely cured, it was removed from the mold. The specific resistance and thermal conductivity of the obtained molded article were measured. The results are shown in Table 1.

Reference Example 1 The cubic nitriding used in Example 1 had the following exceptions: fused silica powder with a particle size of 50 microns was used instead of boron powder.
The same procedure as in Example 1 was carried out. When the specific resistance and thermal conductivity of the molded product were measured, the results were as shown in Table 1.

Reference Example 2 The cubic nitriding used in Example 1 was carried out in the same manner as in Example 1, except that graphite powder with a particle size of 50 microns was used instead of boron powder. Although ultraviolet irradiation was continued for 10 minutes, only the surface was cured, and the deep part below 0.03 cm was not cured.

Table 1 Example 1. The molded products of Reference Example 1 both had high specific resistance;
Although electrical insulation was observed, the molded product of Example 1 was found to be 100 times or more superior in thermal conductivity. Further, in Reference Example 2, graphite powder with excellent thermal conductivity was used, but it was not cured by ultraviolet irradiation.

Example 2 100 g of cubic boron nitride powder with a particle size of 10 microns was prepared from 10 g of diarylidene pentaerythritol, pentaerythritol tetrathioglycolate Log, 10 g of hrifthyrol propane triacrylate, and 0.01 g of 2-hydroxypropiophenone. After being well dispersed in a mixture of 3cm wide, 50m long, and 0.5cm deep.
It was poured into a 3 cm mold and irradiated with ultraviolet rays for 40 seconds using a 20 W/cm high pressure mercury lamp. After it was completely cured, it was removed from the mold. The specific resistance and thermal conductivity of the obtained molded article were measured. The results are shown in Table 2.

Reference Example 3 The cubic nitriding used in Example 2 was carried out in the same manner as in Example 2, except that quartz glass powder with a particle size of 10 microns was used instead of boron powder. When the specific resistance and thermal conductivity of the molded article were measured, the results were as shown in Table 2.

Reference Example 4 The cubic nitridation used in Example 2 was as follows, except that silicon carbide powder with a particle size of 10 microns was used instead of boron powder.
The same procedure as in Example 2 was carried out. Although ultraviolet irradiation was continued for 10 minutes, only the surface was cured, and the deep part below 0.03 cm was not cured.

Table 2 Example 2. The molded products of Reference Example 3 both have high specific resistance;
Although electrical insulation was observed, the molded product of Example 2 was found to be 100 times or more superior in thermal conductivity. Further, in Reference Example 4, silicon carbide powder with excellent thermal conductivity was used, but it was not cured by ultraviolet irradiation.

Example 3 Alpha alumina single crystal powder 100 with a particle size of 50 microns
g is bisphenol A epoxy acrylate (molecular weight
524) 20g, pentaerythritol tetraacrylate 10g, benzoin isopropyl ether 0.2g
After being well dispersed in a mixture consisting of
The mixture was poured into a mold having a diameter of 5 cm, a length of 5 cm, and a depth of 0.3 cm, and was irradiated with ultraviolet rays for 45 seconds using a 20 W/cm high-pressure mercury lamp. After it was completely cured, it was removed from the mold. The specific resistance and thermal conductivity of the obtained molded product were measured. The results are shown in Table 3.

Reference Example 5 The same procedure as in Example 3 was conducted except that fused silica powder with a particle size of 50 microns was used instead of the alpha alumina single crystal powder used in Example 3. When the specific resistance and thermal conductivity of the molded product were measured, the results were as shown in Table 3.

Reference Example 6 The same procedure as in Example 3 was conducted except that alumina polycrystalline powder having a particle size of 50 microns was used instead of the alpha alumina single crystal powder used in Example 3. Although ultraviolet irradiation was continued for 10 minutes, only the surface was cured, and the deep part of 0.1 cm or less was not cured.

Table 3 Example 3. The molded products of Reference Example 5 both had high specific resistance;
Although electrical insulation was observed, the molded product of Example 3 was found to be 10 times or more superior in thermal conductivity. Further, Reference Example 6 is an example in which polycrystalline alumina was used, but in this case, it was not hardened to the deep part by ultraviolet rays.

Example 4 Synthetic diamond powder (type II) with a particle size of 10 microns 9
0g was well dispersed in a mixture consisting of 75g of bisphenol A/epichlorohydrin condensed epoxy resin (epoxy equivalent: 190) and 2g of dimethylphenylsulfooxynium hexafluorophosphate, and then defosolated, and then the size was 3cm wide, 5cm long, and deep. It was poured into a 0.3 cm mold and irradiated with ultraviolet rays for 35 seconds using a 20 W/cm high pressure mercury lamp. After it was completely cured, it was removed from the mold. The specific resistance and thermal conductivity of the obtained molded product were measured. The results are shown in Table 4.

Reference Example 7 Synthetic diamond powder (II
The same procedure as in Example 4 was conducted except that quartz glass powder with a particle size of 10 microns was used instead of the mold. When the specific resistance and thermal conductivity of the molded product were measured, the results were as shown in Table 4.

Reference Example 8 Synthetic diamond powder (II
The same procedure as in Example 4 was carried out except that graphite having a particle size of 10 microns was used instead of the mold. UV irradiation 1
Although it continued for 0 minutes, only the surface was cured, and the deep part below 0.05 cm was not cured.

Table 4 Example 4. The molded products of Reference Example 7 both had high specific resistance;
Although electrical insulation was observed, the molded product of Example 7 was found to be 200 times better in thermal conductivity. Further, Reference Example 8 is an example in which graphite powder was used, but in this case, it was not hardened to the deep part by ultraviolet irradiation.

Patent applicant: Showa Denko Co., Ltd. Representative Patent Attorney Kikuchi Sei -

Claims (1)

[Claims] A photocurable composition comprising a boron nitride powder bundle, diamond powder, or alpha alumina single crystal powder dispersed in a monomer and/or oligomer, and a photosensitizer added thereto.