JPH06256464A - Casting resin - Google Patents

Abstract

PURPOSE:To produce a bisoxazoline/epoxy type casting resin whose curing reaction can be easily controlled and which can give a cured product of a controlled heat distortion temperature without using any flexibilizer and is highly balanced among heat resistance, toughness and mechanical properties without detriment to the environmental resistance and workability. CONSTITUTION:This casting resin comprises a composition comprising a linear oligomer having bicyclic rings in the main chain and prepared by polymerizing under heating a mixture of 1mol of an epoxy compound having at least two epoxy groups in the molecule and a uerage epoxy equivalent of 170 to 200 and 0.8-1.2mol of an oxazoline compound of the formula and polyaddition type epoxy curing agent for the oligomer. In the formula, X is a bivalent organic group; D is a bivalent organic group; (n) is 0 or 1; and the ring structure is five-membered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting resin, and more particularly to a casting resin suitable as an insulating material or a structural material for electric devices and electronic machine parts.

[0002]

2. Description of the Related Art Among resins used as insulating materials or structural materials for electric equipment and electronic machine parts, epoxy resins cured with an acid anhydride are superior to other thermosetting resins or thermoplastic resins. It has excellent insulation and mechanical properties, and is widely used as various electrical insulation materials.

However, since the acid anhydride-cured epoxy resin generally has a high brittleness, it is necessary to pay sufficient attention to the occurrence of cracks, particularly when it is used as a constituent material such as a molded product having a metal embedded therein. Therefore, in order to improve the crack resistance, it is general to use an epoxy resin having a large molecular weight or blend a flexibility-imparting agent. However, these methods have the drawback of lowering the heat resistance of the cured product. Further, in order to achieve both heat resistance and crack resistance, a resin system having a phase separation structure in which a rubber-like component is dispersed and a resin system having an interpenetrating network structure have been proposed. However, it has not been widely used as an insulating material or a structural material for electric devices and electromechanical parts because of some difficulties in adhesiveness, workability and the like.

On the other hand, it is known that a high-strength thermosetting resin can be obtained by reacting a bisoxazoline compound, which is one kind of cyclic imino ether, with a dicarboxylic acid by heating in the presence of a phosphite. No. 59-1533. The present inventors have already obtained a cured product obtained from a bisoxazoline compound and an epoxy resin, which is equivalent to or better than the conventional epoxy resin in physical heat resistance, crack resistance, and mechanical strength. It was found that, JP-A-62-188774,
It is proposed as Japanese Patent Laid-Open No. 62-18875.

[0005]

However, in the composition comprising the above epoxy compound and the bisoxazoline compound, the average epoxy equivalent of the epoxy resin is 135 to 40.
When the resin of No. 0 is used, a liquid resin composition having particularly good workability and a cured product having high strength can be obtained. In these resin systems, bisoxazoline of 0.
A cured product having the maximum crosslink density can be obtained by reacting 5 mol, but when the reaction exceeds a certain region, the crosslinking reaction rapidly progresses, so that the cured product is apt to have curing strain or sink mark. There was a problem.

On the other hand, in consideration of environmental resistance such as chemical resistance, generally, the compounding ratio of the seed epoxy and the curing agent is preferably 0.7 to 1.0 in equivalent ratio, but the epoxy and the bisoxazoline are good. When the equivalence ratio is set to a composition ratio close to 1 in the composition of the compound, the heat distortion temperature becomes extremely high, resulting in a decrease in toughness and a decrease in substantial mechanical strength.

In order to improve the toughness, there is a method of lowering the heat distortion temperature by adding a high molecular weight epoxy resin or a flexibility-imparting agent. However, when a high molecular weight epoxy compound is used, the hydroxyl group contained in the epoxy compound reacts rapidly with the oxazoline compound, the pot life is shortened, and the heat distortion temperature of the cured product is extremely lowered. is there. Further, there is a problem that use of the flexibility-imparting agent generally deteriorates the environment resistance and heat deterioration characteristics of the cured product.

The present invention has been made in order to solve the above problems, and it is easy to control the curing reaction, and to control the heat distortion temperature of the cured product without adding a flexibility-imparting agent. It can be done without sacrificing environment resistance and workability.
It is an object of the present invention to provide a bisoxazoline / epoxy type casting resin in which heat resistance, toughness and mechanical properties are highly balanced.

[0009]

[Means and Actions for Solving the Problems] Based on the results of the research so far, the inventors of the present invention have conducted diligent research to obtain a higher-performance casting resin, and as a result, the conventional bisoxazoline compound was obtained. It has been found that a curing epoxy resin and a glass transition temperature of a cured product can be easily controlled as compared with an epoxy resin, and a casting epoxy resin having a high balance of heat resistance, mechanical strength and toughness can be obtained. .

That is, the casting resin according to the present invention has a general formula based on 1 mol of an epoxy compound having at least two epoxy groups in one molecule and having an average epoxy equivalent of 170 to 200.

[Chemical 2] A linear oligomer containing a bicyclo ring on the main chain, which is obtained by mixing and heat-polymerizing an oxazoline compound represented by the formula at a mixing ratio of 0.8 to 1.2 mol, and a polyaddition type epoxy curing agent which is a curing agent for this oligomer. And a resin composition comprising an agent.

It is also possible to compose at least one of the particulate filler and the fibrous filler, that is, individually or in combination, in an amount of 55% by volume or less based on the entire resin composition. it can.

The epoxy compound used in the above resin composition is not particularly limited as long as it has at least two epoxies in one molecule, and examples thereof include bisphenol A type epoxy resin and bisphenol F type epoxy. Specific examples include resins, alicyclic epoxy resins, hydrogenated bisphenol A type epoxy resins, and heterocyclic epoxy resins such as triglycidyl isocyanate and hydantoin epoxy. These epoxy compounds are used alone or as a mixture of two or more kinds.

Further, as the oxazoline compound used in the casting resin according to the present invention and represented by the above general formula, the following compounds are specifically exemplified by the value of n.

That is, when n = 0, 2,2'-bis (2-oxazoline), 2,2'-bis (4-methyl-2-oxazoline), 2,2'-bis (4,4) -Dimethyl-2-oxazoline), 2,2'-bis (4-ethyl-2-oxazoline), 2,2'-bis (4,4-diethyl-2-oxazoline), 2,2'-bis (4 -Propyl-2-oxazoline), 2,2'-bis (4-butyl-2-oxazoline), 2,2'-bis (4-phenyl-2-oxazoline), 2,2'-bis (4-cyclohexyl) -2-oxazoline), 2,2'-bis (4
-Benzyl-2-oxazoline) and other bisoxazoline compounds.

When n = 1, 2,2'-p-phenylenebis (2-oxazoline), 2,2'-m-phenylenebis (2-oxazoline), 2,2'-o-phenylene Bis (2-oxazoline), 2,2'-p-phenylene bis (4-methyl-2-oxazoline), 2,
2'-p-phenylene bis (4,4-dimethyl-2-oxazoline), 2,2'-m-phenylene bis (4-methyl-2-oxazoline), 2,2'-m-phenylene bis (4 4-dimethyl-2-oxazoline), 2,
2'-ethylenebis (2-oxazoline), 2,2'-
Tetramethylene bis (2-oxazoline), 2,2'-
Hexamethylenebis (2-oxazoline), 2,2'-
Octamethylenebis (2-oxazoline), 2,2'-
Decamethylene bis (2-oxazoline), 2,2'-ethylenebis (4-methyl-2-oxazoline), 2,
2'-tetramethylene bis (4,4-dimethyl-2-oxazoline), 2,2'-cyclohexylene bis (2-
There are bisoxazoline compounds such as oxazoline) and 2,2′-diphenylenebis (2-oxazoline).

These compounds are used alone or as a mixture of two or more kinds. Among them, 2,2′-from the viewpoint of good compatibility with acid anhydride and easy handling.
m-Phenylenebis (2-oxazoline) is preferred.

The blending amount of these oxazoline compounds is
The reaction temperature of epoxy and oxazoline is 1 when the range is 0.8 to 1.2 mol with respect to 1 mol of the epoxy compound.
As a result of examination by gel permeation chromatography and infrared absorption spectrum, it was found that in the range of 20 to 140 ° C., only linear oligomers are formed and the three-dimensional crosslinking reaction hardly progresses. The oligomer obtained by this reaction is 1
It has a low viscosity at a temperature of around 20 ° C., and it is possible to add a high amount of filler.

Next, a polyaddition type curing agent for epoxy resin is added to the oligomer and the mixture is cured by heating. Specific examples of the polyaddition type curing agent include acid anhydrides such as phthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methyl nadic acid, and phenol such as phenol novolac. , Aliphatic amines such as diethylenetriamine and triethylenetetramine, aromatic amines such as metaxylenediamine, diaminodiphenylmethane and diaminogenylsulfone, polymercaptans such as dimer acid polyamide and polysulfide. Among the above curing agents, acid anhydride curing agents are preferable from the viewpoints of compatibility with the oligomer and ease of handling.
The curing conditions are generally set on the basis of the conditions where the rise in the glass transition temperature is saturated, but in the case of the main curing system, the curing is generally carried out at 120 to 170 ° C. for about 10 to 30 hours to obtain a strong curing. A cured product is obtained. Further, in the main curing system, the curing rate can be increased by adding a tertiary amine, imidazole, a Lewis acid complex, an organometallic complex, a phosphite ester or the like, if necessary.

As described above, in the present curing system, once the linear oligomer composed of epoxy / bisoxazoline is sufficiently formed, the curing agent is further reacted to three-dimensionally crosslink, so that the conventional linear chain oligomer is used. As compared with a curing system in which oligomer growth and three-dimensional crosslinking reaction proceed competitively, it is possible to obtain a high-strength cured product having a small curing shrinkage after gelation and a high impact resistance and toughness. Further, the heat resistance of the cured product can be arbitrarily adjusted depending on the type and blending amount of the polyaddition type curing agent used.

In the casting resin composition of the present invention, a filler having any type, composition and shape can be blended as long as the workability is not impaired. For example, as a particulate filler, silica, alumina, talc, calcium carbonate, aluminum hydroxide, kaolin, clay, dolomite, mica powder, silicon carbide, glass powder, carbon, graphite, barium sulfate, titanium dioxide, boron nitride, nitriding Silicon, etc. are mentioned. Further, as the fibrous filler, warlastonite, potassium titanate whiskers, glass fibers, alumina fibers, silicon carbide fibers,
Examples thereof include boron fiber, carbon fiber, aramid fiber, phenol fiber, and metal whiskers. These fillers are used alone or as a mixture of two or more kinds. The total blending amount is set to 55% by volume or less with respect to the entire composition, and is determined according to the casting conditions and the required characteristics for the cured resin. When the total content exceeds 55% by volume, the viscosity of the composition increases remarkably, which makes casting work difficult.

In the resin composition of the present invention, additives such as a release agent, a flame retardant, an antioxidant, a pigment and a dye may be added, if necessary.

The casting resin composition of the present invention can be easily produced by mixing and stirring the above-mentioned components by a conventional method, and then heat-curing the mixture without using a catalyst or a curing accelerator as appropriate. Furthermore, by mixing the filler in a high proportion, the curing shrinkage can be reduced, and therefore it is useful as a sealing material for large-sized castings and semiconductors.

[0023]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples.

Example 1 DGEBA type epoxy resin as an epoxy compound (trade name: GY260, manufactured by Ciba Geigy, epoxy equivalent: 1
90), 2,2'-m-phenylenebis (2-oxazoline) as an oxazoline compound (abbreviation: 1,3-P)
BO, manufactured by Takeda Pharmaceutical Co., Ltd.) and mixed at an equimolar amount, and the temperature is 120 ° C.
Was reacted for 4 hours to obtain an oligomer having a bicyclo ring on the main chain. Next, GY26 used in the above reaction as a curing agent
Phthalic anhydride (trade name: HT901, manufactured by Ciba Geigy) in an equimolar amount to 0, and the oligomer 10 as a promoter
120 parts by weight of a resin composition obtained by vacuum mixing 1 part by weight of triphenyl phosphite with 0 part by weight of the oligomer.
Cast in a mold preheated to ℃, vacuum degassing, then 1 at 140 ℃
After heating for 5 hours for primary curing, the test piece was released from the mold, and post-curing was performed at 160 ° C. for 15 hours to prepare a test sample.

Example 2 DGEBA type epoxy resin as an epoxy compound (trade name: GY260, manufactured by Ciba Geigy, epoxy equivalent: 1
90), 2,2'-m-phenylenebis (2-oxazoline) as an oxazoline compound (abbreviation: 1,3-P)
BO, manufactured by Takeda Pharmaceutical Co., Ltd.) and mixed at an equimolar amount, and the temperature is 120 ° C.
Was reacted for 4 hours to obtain an oligomer having a bicyclo ring on the main chain. Next, GY26 used in the above reaction as a curing agent
Methyl hexahydrophthalic anhydride (trade name: HN5500, manufactured by Hitachi Chemical Co., Ltd.) in an equimolar amount to 0, and 1 part by weight of triphenyl phosphite as a promoter with respect to 100 parts by weight of the oligomer, and the oligomer and vacuum. The mixed resin composition was cast into a mold preheated to 120 ° C., degassed under vacuum, and then primary cured at 140 ° C. for 15 hours, and then the test piece was released from the mold and kept at 160 ° C. for 15 hours. Post-curing was carried out under the conditions to prepare test samples.

Example 3 To the resin composition prepared in Example 1, 4 particles of particulate alumina (manufactured by Showa Denko KK: average particle size 12 μm) were used as a filler.
5% by volume was compounded and cured under the same curing conditions as in Example 1 to prepare a test sample.

Example 4 4 particles of particulate alumina (manufactured by Showa Denko KK: average particle size: 12 μm) were added to the resin composition prepared in Example 2 as a filler.
5% by volume was compounded and cured under the same curing conditions as in Example 1 to prepare a test sample.

Comparative Example 1 As a epoxy compound, a DGEBA type epoxy resin (trade name: CT200, manufactured by Ciba Geigy, epoxy equivalent: 3)
90) 90 parts by weight and alicyclic epoxy resin (trade name: C
Y175, manufactured by Ciba-Geigy) and 10 parts by weight of phthalic anhydride as a curing agent (trade name;
HT901, manufactured by Ciba-Geigy Co., Ltd.) was added in an amount of 0.9 equivalent with respect to all the epoxy compounds present in the reaction system. Then, the resin composition vacuum-mixed at 115 ° C. with a universal mixer was poured into a mold preheated to 120 ° C., degassed under vacuum, and heated at 120 ° C. for 15 hours, and then the test piece was released from the mold. And post-cure 15
A test sample was prepared by carrying out the test at 0 ° C. for 15 hours.

Comparative Example 2 DGEBA type epoxy resin (trade name: GY260, manufactured by Ciba Geigy Co., epoxy equivalent: 1 as an epoxy compound
90), as an oxazoline compound, 2,2'-m-phenylenebis (2-oxazoline) (abbreviation: 1,3-P)
BO, manufactured by Takeda Yakuhin Kogyo Co., Ltd.) and mixed in vacuum into a resin composition preheated to 120 ° C., cast into a mold, vacuum defoamed, and heated at 150 ° C. for 15 hours, and then a test piece. Was released from the mold and post-cured at 150 ° C. for 15 hours to prepare a test sample.

COMPARATIVE EXAMPLE 3 Particulate alumina (manufactured by Showa Denko KK: average particle size 12 μm) was added to the resin composition prepared in Comparative Example 1 as a filler.
A resin composition, which was mixed at 0% by volume and vacuum mixed at 110 to 120 ° C. by a universal mixer, was cast into a mold preheated to 120 ° C., and cured under the same curing conditions as in Comparative Example 1 to prepare a test sample. It was made.

Comparative Example 4 4 particles of particulate alumina (manufactured by Showa Denko KK: average particle size 12 μm) were added to the resin composition prepared in Comparative Example 2 as a filler.
A resin composition containing 5% by volume and vacuum mixed at 110 to 120 ° C. with a universal mixer was cast into a mold preheated to 120 ° C., and cured under the same curing conditions as in Comparative Example 2 to obtain a test sample. It was made.

In order to evaluate the test samples of Examples 1 to 4 and Comparative Examples 1 to 4 thus prepared, the glass transition temperature, the tensile strength, the mechanical toughness value, and the crack resistance were measured. The results shown in Table 2 were obtained. The glass transition temperature Tg was measured by using a differential scanning calorimeter (DSC), and the thermal shock resistance was measured by M20 flat washer method. The mechanical strength characteristics were measured according to JIS-K6911, and the fracture toughness was measured according to ASTM E 399-83.

[0033]

[Table 1]

[0034]

[Table 2]

As is clear from the results shown in Tables 1 and 2, the test samples according to Examples 1 to 4 were Comparative Examples 1 to 4.
Compared with, the glass transition temperature is high, the heat resistance is excellent, the mechanical strength is large, and the heat resistance and mechanical property levels as well as the heat resistance and toughness levels are high and excellent, which has been difficult to achieve in the past. It is possible to provide a casting resin that satisfies both heat resistance and toughness.

[0036]

As described above, according to the casting resin of the present invention, the curing reaction can be easily controlled, and the oxazoline / epoxy-based casting resin in which heat resistance, toughness, and mechanical properties are highly balanced is provided. A mold resin can be provided, and its industrial value is extremely large.

Claims (2)

[Claims] 1. A compound represented by the general formula: embedded image with respect to 1 mol of an epoxy compound having an average epoxy equivalent of 170 to 200 and having at least two epoxy groups in one molecule. A linear oligomer containing a bicyclo ring on the main chain, which is obtained by mixing and heat-polymerizing an oxazoline compound represented by the formula at a mixing ratio of 0.8 to 1.2 mol, and a polyaddition type epoxy curing agent which is a curing agent for this oligomer. A casting resin comprising a resin composition comprising an agent. 2. A casting characterized in that at least one of a particulate filler and a fibrous filler is blended with the entire resin composition according to claim 1 in a proportion of 55% by volume or less. Resin.