JPS621610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel curable resin composition. More specifically, the present invention relates to a curable resin composition comprising an epoxy resin and a polyfunctional carboxylic anhydride that can be cured by irradiation with light or radiation.

Epoxy resins have been used in a wide range of fields as high-performance materials. In particular, acid anhydride-cured epoxy resins are known to have excellent mechanical, electrical, and thermal properties.

When curing an epoxy resin with an acid anhydride (i.e., carboxylic anhydride), the epoxy resin and acid anhydride are usually mixed so that 0.5 to 1.0 carboxyl groups are introduced to one epoxy group. In addition, tertiary amines and metal chelate compounds are added as heat curing catalysts. This epoxy resin compound is applied, impregnated or cast onto the object to be treated, and then cured by heating.

The conventional method of curing epoxy resins with acid anhydrides requires heating at high temperatures for long periods of time (for example, several hours to several tens of hours at 150 to 180°C), which is not preferable from the viewpoint of energy saving. Furthermore, when this resin compound is used for impregnation or casting, there is a risk that the resin compound will leak out from the object to be treated during heating, resulting in voids or dripping in the object.

The present invention was made in order to eliminate the drawbacks of conventional curable resin compositions as described above, and provides a curable resin that can be completely cured by first irradiating with light or radiation and then heating. The purpose is to provide a composition.

In order to achieve this objective, the present inventors focused on Lewis acids as curing catalysts for curing epoxy resin-carboxylic anhydride compositions, and as a result of extensive studies, discovered that Lewis acids are released by irradiation with light or radiation. The inventors have discovered that the above object can be achieved by adding a compound and a quaternary ammonium salt of a Lewis acid to an epoxy resin-carboxylic anhydride composition, and have completed the present invention.

That is, the present invention provides (a) an epoxy resin having at least two or more epoxy groups in the molecule, (b) a polyfunctional carboxylic anhydride copolymerizable with the epoxy resin, and (c) It consists of a compound that releases a Lewis acid and (d) a quaternary ammonium salt of a Lewis acid, and has a carboxylic acid anhydride corresponding to 0.2 to 0.8 mol of carboxyl group per 1 mol of epoxy group of the epoxy resin, and has an anhydride with the epoxy resin. 100 parts of carboxylic acid mixture (parts by weight, same below)
0.05 to 5 parts of a compound that releases a Lewis acid by light or radiation radiation and a quaternary part of a Lewis acid.
A resin composition for impregnation or casting, which is first irradiated with light or radiation and then cured by applying heat. By using a curable resin composition made of the above-mentioned specific components, the resin composition may leak out from the object to be treated during heat curing and create voids in the object, unlike conventional curable resin compositions. In addition, the drawbacks of sagging caused by the occurrence of sagging have been completely eliminated.
Since the curable resin composition impregnated into the object to be treated is cured into a semi-gel to gel state by irradiation with light or radiation, the resin composition does not leak out from the object during heat curing. Therefore, it is possible to obtain a molded article without voids or sag, which is a very remarkable effect.

Examples of epoxy resins having at least two epoxy groups in the molecule used in the curable resin composition of the present invention include 2,2'-bis(p-hydroxyphenyl)propane, 2,2'-bis( 4-
Glycidyl ethers of aromatic phenols such as hydroxy-3,5-dibromphenyl)propane, 1,1,2,2-tetrakis(p-hydroxyphenyl)ethane, 4,4-dihydroxydiphenyl, resorcinol, catechol, and hydroquinone;
Glycidyl ethers such as phenol novolac and cresol novolac, vinylcyclohexene diepoxide, limonene diepoxide, dicyclopentadiene diepoxide, (3', 4'-epoxycyclohexylmethyl)-3, 4-epoxycyclohexane carboxylate, (3 ′・4′-epoxy-6′-methylcyclohexylmethyl)-3・4
-Epoxy-6-methylcyclohexanecarboxylate, 3-(3',4'-epoxycyclohexyl)-2,4-dioxaspiro(5,5)-8,9
-Alicyclic epoxy resins such as epoxyundecane, 3-(glycidyloxyethoxyethyl)-2,4-dioxaspiro(5,5)-8,9-epoxyundecane, triglycidyl isocyanurate, 5,5-dimethylhydatoin N・N'-
Examples include heterocyclic epoxy resins such as diglycidyl derivatives, and one or more of these may be used. In that case, an epoxy compound containing one epoxy group in the molecule may be blended as a diluent.

Examples of the polyfunctional carboxylic anhydride copolymerizable with the epoxy resin used in the curable resin composition of the present invention include phthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, methylnadic acid, and methyltetrahydrophthalic acid. , dibasic acid anhydrides such as succinic acid, dodecenylsuccinic acid, methylsuccinic acid, and citraconic acid, and polybasic acid anhydrides such as trimellitic anhydride and pyromellitic anhydride, all of which can be used alone or in combination. I can do it. In that case, it is also possible to blend a monobasic carboxylic acid anhydride in order to adjust the crosslinking density of the cured product.

Examples of compounds that release Lewis acids upon irradiation with light or radiation used in the curable resin composition of the present invention include general formula (1): (In the formula, MXn represents a complex anion, M is Sb,
Fe, Sn, Bi, Al, Ga, In, Ti, Zr, Sc, V,
Transition metals such as Cr, Mn, Co or B, P,
Non-metals such as As, X is F, halogen such as Cl, n is an integer, such as BF ^- ₄ , PF ^- ₆ ,
AsF ^- ₆ , SbF ^- ₆ , ^FeCl2-4 , SnCl ^- ₆ , SbCl ^- _{6 ,
BiCl} ^2-5
etc. Y is a nitro group, a hydroxyl group, a halogen group, an N-morpholino group, an alkyl group, an alkoxy group, an aryl group, an amino group, an arylamino group,
Diazonium salts of Lewis acids represented by arylmercapto groups, m is the valence of MXn, general formula (2): (In the formula, MXn and m are the same as above, R ¹ and R ²
is a nitro group, a hydroxyl group, a halogen group, an alkyl group,
diaryliodonium salts of Lewis acids represented by alkoxy groups, aryl groups, amino groups, arylamino groups, arylmercapto groups, etc.);
General formula (3): (In the formula, MXn and m are the same as above, Q ¹ is S,
Triphenylonium salts of Lewis acids represented by Group A elements such as SeSn and general formula
(Four): (In the formula, MXn and m are the same as above, Q ² is P,
Particularly preferred are triphenyl alkyl (or alkoxy, aryl, etc.) onium salts of Lewis acids represented by group a elements such as N and Sb, and R ³ is an aliphatic or aromatic group. are compounds that release Lewis acids represented by general formulas (2), (3) and (4).

Examples of the quaternary ammonium salt of a Lewis acid used in the curable resin composition of the present invention include the general formula
(Five): (In the formula, MXn and m are the same as above, Z ¹ , Z ² , Z ³
and Z ⁴ is an alkyl group consisting of 1 to 8 carbon atoms,
The aliphatic group substituted with an aliphatic group such as an alkoxy group, a halogen group, a nitro group, an amino group, etc.
Phenyl group consisting of 6 to 15 carbon atoms, tolyl group,
An aromatic group such as a benzyl group or a naphthyl group, or an aromatic group substituted with a halogen group, a nitro group, an amino group, a hydroxyl group, etc., and may be the same or different. Examples include quaternary ammonium salts of Lewis acids,
In general formula (5), it is particularly preferable that
Z ¹ to ^{Z 4} are quaternary ammonium salts of Lewis acids each consisting of the aliphatic group or substituted aliphatic group.

In the curable resin composition of the present invention, the blending ratio of epoxy resin and carboxylic anhydride is such that carboxylic anhydride is equivalent to 0.2 to 0.8 moles of carboxyl groups per mole of epoxy groups in the epoxy resin. A curable resin composition can be obtained that can provide a cured product with excellent properties such as properties, electrical properties, and thermal properties. When the blending ratio of carboxylic anhydride is greater than the carboxylic anhydride equivalent to 0.8 mol of carboxyl groups per 1 mol of epoxy groups in the epoxy resin, the curability of the resulting curable resin composition decreases significantly, and the carboxyl groups
When the amount is less than 0.2 mol of carboxylic anhydride, not only the curability of the curable resin composition is reduced, but also the properties of the resulting cured product are also reduced, both of which are unfavorable. In addition, the compounding ratio of the compound that releases a Lewis acid and the quaternary ammonium salt of a Lewis acid upon irradiation with light or radiation is 0.05 parts (parts by weight, the same applies hereinafter) to 100 parts (parts by weight, the same applies hereinafter) of the mixture of epoxy resin and carboxylic anhydride. ~5 parts each are employed, thereby obtaining a curable resin composition that is rapidly cured by light or radiation irradiation. A mixture of an epoxy resin and a carboxylic anhydride in which the compound that releases a Lewis acid when irradiated with light or radiation and the quaternary ammonium salt of a Lewis acid are mixed together.
If the amount is less than 0.05 parts per 100 parts, the rate of curing by light or radiation irradiation or heat will be slowed down, and if the amount is more than 5 parts, not only will the rate of increase in the curing rate decrease. However, the properties of the resulting cured product also tend to deteriorate, and both are unfavorable.

To cure the curable resin composition of the present invention,
It is preferable to first irradiate with light or radiation. In the case of light irradiation, a lamp that efficiently generates light with a wavelength of 280 to 400 mm is used as a light source, such as a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a xenon lamp, or a metal halide lamp. Irradiation is performed for about 1 second to 10 minutes. In addition, in the case of radiation irradiation, electron beams, gamma rays, etc. are used as radiation sources, and the absorbed dose is 0.05~
Irradiation is about 10 Mrad. By this light or radiation irradiation, at least the resin surface layer is hardened, becoming semi-gel-like and fluidity significantly reduced. The resin composition is then completely cured by heating this semi-gel-like resin. The heating conditions vary depending on the type of heat curing catalyst used, but for example, a temperature of 120 to 180° C. for several hours is employed.

The curable resin composition of the present invention provides an acid anhydride-cured epoxy resin with excellent mechanical properties, electrical properties, and thermal properties, and is particularly suitable for use in impregnation, casting, etc. The effect is great. That is, a workpiece is impregnated with the curable resin composition of the present invention, irradiated with light or radiation at room temperature to cure the resin composition on the surface layer of the workpiece, and then heated for complete curing. However, in this case, since the resin composition on the surface layer of the object to be treated is cured, the resin composition is prevented from flowing out due to a decrease in resin viscosity during heating. Furthermore, when the curable resin composition of the present invention is used for casting, for example, the "mold" used can be simplified for the same reasons as mentioned above.

In addition, the curable resin composition of the present invention may include an organic solvent for viscosity adjustment, an inorganic filler, as long as it does not significantly inhibit the light or radiation curability or heat curability of the epoxy resin-carboxylic anhydride composition.
Dyes, pigments, ultraviolet absorbers, etc. may be added as appropriate.

The curable resin composition of the present invention can be applied to metals, for example.
It is used by coating, impregnating, or casting on materials such as plastic, wood, glass, concrete, and ceramics.

Next, the curable resin composition of the present invention will be specifically explained with reference to Examples.

Example 1 100 g of Epicote 828 (epoxy resin manufactured by Ciel Chemical Co., Ltd., trade name, epoxy equivalent: 198) and
HN-2200 [carboxylic anhydride manufactured by Hitachi Chemical Co., Ltd., trade name, main component: methyltetrahydrophthalic anhydride] 4,4'-dimethyldiphenyl iodonium hexafluorophosphate was added to a mixture of 80 g.
A curable resin composition was prepared by blending 0.9 g and 0.9 g of tetraethylammonium hexafluorophosphate.

Next, each of the prepared curable resin compositions was weighed out to a depth of about 3 mm on an aluminum shear coated with a release agent, and a high-pressure mercury lamp [H25-
UVA (manufactured by Mitsubishi Electric Co., Ltd.) was used to irradiate ultraviolet rays in the air at a distance of 15 cm and a conveyor speed of 4 m/min, changing the number of passes. In that case, the curable resin composition was cured into a semi-gel to gel-like state.

This semi-gel-like to gel-like hardened resin was removed from the aluminum shear and placed in a large amount of acetone.
Extraction was carried out at room temperature for 72 hours, then vacuum dried at 100°C, and weighed to measure the gel fraction. FIG. 1 shows the relationship between the gel fraction and the amount of ultraviolet irradiation (number of passes) of the prepared curable resin composition.

From FIG. 1, it is clear that the curable resin composition of the present invention is easily cured by light irradiation.

Example 2 Using the curable resin composition prepared in Example 1,
The gel-like cured resin obtained by irradiating 20 passes of ultraviolet rays in the same manner as in Example 1 was heated at 130° C. for different heating times without exposing it to light.

Then, the gel fraction of each heat-treated cured resin was measured in the same manner as in Example 1. FIG. 2 shows the relationship between the gel fraction of the heat-treated cured resin and the heating time.

From FIG. 2, it is clear that the curable resin composition of the present invention progresses in curing even by heating after irradiation with light.

Comparative Example 1 The gel fraction of the composition used in Example 1 except for tetraethylammonium hexafluorophosphate was irradiated with a high-pressure mercury lamp in the same manner as in Example 1, and the results were as shown in Figure 3. It was hot.

Comparative Example 2 The composition used in Comparative Example 1 was irradiated with a high-pressure mercury lamp for 20 passes, and then heated and cured in the same manner as in Example 2, and the gel fraction was measured, as shown in Figure 4. It was hot.

Comparative Examples 3 to 6 Instead of 0.9 g of tetraethylammonium hexafluorophosphate used in Example 1, 0.9 g of dicyandiamide, 0.9 g of imidazole, 0.9 g of benzyldimethylamine which is a tertiary amine, or Co (which is an organic acid metal salt) ) 0.9 g of acetylacetonate (corresponding to Comparative Examples 3 to 6, respectively) was irradiated with a high-pressure mercury lamp for 40 passes in the same manner as in Example 1, but the gel fraction was 0 in all cases. Ta.

Furthermore, the above composition was treated under the same conditions as in Example 2.
Despite heating for several hours, the curing rate was extremely slow.

Comparative Example 7 In Example 3, an attempt was made to cure the resin in the same manner as in Example 3, except that 0.5 g of diphenyliodonium tetrafluoroborate was not used and irradiation with a high-pressure mercury lamp was not performed. The composition leaked out and a proper cured product could not be obtained.

Example 3 Epicote 828 (mentioned above) 100g and HN-2200
(Previous) To 50 g of the mixture, 0.5 g of diphenyliodonium tetrafluoroborate and tetra-n
-Butylammonium hexafluorophosphate
A curable resin composition was prepared by blending 1.0 g.

Next, a coil (outer diameter: 22 cm, inner diameter: 20 cm, length: 25 cm) was vacuum impregnated using the prepared curable resin composition to obtain a resin-impregnated coil. While rotating the obtained resin-impregnated coil, ultraviolet rays were irradiated in the air using a high-pressure mercury lamp (described above) under the conditions of a vertical irradiation distance of 15 cm, a coil rotation speed of 20 revolutions/minute, and an irradiation time of 5 minutes. The irradiated coil has a hardened resin composition on its surface.
Moreover, the appearance was extremely good.

The irradiated coil was then placed in a 130° C. oven and heated for 8 hours to cure the impregnated resin composition of the coil. The resulting coil was resin-embedded and had an excellent appearance.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the gel fraction and the amount of ultraviolet irradiation (number of passes) of the curable resin composition of the present invention.
A graph showing the relationship between gel fraction and heating time of a cured product obtained by heating at 130°C after 20 passes of ultraviolet irradiation. Figure 3 shows the composition of Example 1 except for tetraethylammonium hexafluorophosphate. A graph showing the relationship between the gel fraction and the amount of ultraviolet irradiation for the composition and FIG. It is a graph showing the relationship between fraction and heating time.

Claims (1)

[Claims] 1 (a) an epoxy resin having at least two epoxy groups in its molecule, (b) a polyfunctional carboxylic anhydride that can be copolymerized with the epoxy resin, (c) a Lewis acid by irradiation with light or radiation. It consists of a compound to be released and (d) a quaternary ammonium salt of a Lewis acid, contains carboxylic anhydride corresponding to 0.2 to 0.8 moles of carboxyl group per mole of epoxy group of the epoxy resin, and contains a mixture of the epoxy resin and the carboxylic anhydride. 0.05 to 5 parts by weight of a compound that releases a Lewis acid upon irradiation with light or radiation, and 0.05 to 5 parts by weight of a quaternary ammonium salt of a Lewis acid, per 100 parts by weight of the mixture.
A resin composition containing parts by weight, which is first irradiated with light or radiation and then cured by applying heat.