JPH0853535A - Epoxy resin composition - Google Patents

Abstract

PURPOSE:To provide an epoxy resin composition containing a poly-functional epoxy resin, a specified curing agent and a specified curing promoter, having a high crosslinking density and a high glass transition temperature, excellent in heat resistance and useful for, e.g. electric and electronic components. CONSTITUTION:This epoxy resin composition contains (A) 100 pts.wt. polyfunctional epoxy resin, (B) a curing agent [the amount used is preferably 0.5 to 1.5 equivalent on hydroxyl group equivalent base based on 1 epoxy equivalent of the component (A)] composed mainly of a polyvalent phenol-based compound of the formula [R1 is a 1 to 12C alkyl; R2 is H, hydroxyl or a 1 to 4C alkyl; (n) is 1 or 2] and (C) preferably 0.1 to 5 pts.wt. curing promoter such as 1,8-diazabicyclo(5.4.0)-undecene-7.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an epoxy resin composition. Specifically, it relates to an epoxy resin composition having excellent heat resistance.

[0002]

2. Description of the Related Art Epoxy resins have hitherto been used in various applications such as paints, laminated plates and electric / electronic materials. Epoxy resins are generally used in combination with a curing agent. Particularly in the field of electric / electronic materials, a phenol novolac resin is used as a curing agent because of its excellent moldability and heat resistance.

However, the conventionally known phenol novolac resin has a glass transition point (Tg) of about 170 ° C. at the highest in a cured product of the epoxy resin, which is satisfactory in a field requiring high heat resistance. is not. Further, the phenol novolac resin is considered to be composed of a mixture of linear molecules having a wide molecular weight distribution containing a low molecular weight substance, and further, since it contains many methylene bonds having a large degree of freedom in its molecular structure, There is a limit to improving the heat resistance by improving the crosslink density and making the molecular structure rigid to reduce the degree of freedom. For this reason, in fields where higher heat resistance is required, polyfunctional phenolic resins are used as curing agents, and heat resistance has been improved to some extent compared to phenol novolac resins, but there is no demand for heat resistance. It is becoming severer year by year, and there is a demand for resins with even higher heat resistance.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an epoxy resin composition whose cured product has a high degree of heat resistance.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems of the prior art, the present inventors have found that a polyvalent polyhydric compound having a specific structure represented by the following general formula (1) as a curing agent It has been found that an epoxy resin composition meeting the object of the present invention can be obtained by using a phenolic compound. The present invention has been completed based on this new finding.

That is, the present invention provides a polyfunctional epoxy resin represented by the general formula (1):

[0007]

Embedded image

(In the formula, R ₁ is an alkyl group having 1 to 12 carbon atoms, and R ₂ is a hydrogen atom, a hydroxy group or 1 to 12 carbon atoms.
4 represents an alkyl group, and n represents an integer of 1 or 2. And a curing agent containing a polyhydric phenol compound as a main component and a curing accelerator.

As the polyfunctional epoxy resin used in the present invention, various known ones can be used. For example, novolac resin type epoxy resins such as orthocresol novolac type epoxy resin and phenol novolac type epoxy resin; polyvalent compounds obtained by condensation reaction of various aldehydes such as hydroxybenzaldehyde, crotonaldehyde, glyoxal and phthalaldehyde with phenols. Epoxy resin obtained from phenol resin and epichlorohydrin; glycidyl ester type obtained by reacting diglycidyl ethers such as bisphenol A and bisphenol F, polybasic acids such as phthalic acid and dimer acid, and epichlorohydrin Epoxy resin; Glycidylamine type epoxy resin obtained by reacting polyamines such as diaminodiphenylmethane and isocyanuric acid with epichlorohydrin; Olefin bond with peracid such as peracetic acid Turned into and linear aliphatic epoxy resins and etc. may be mentioned. Alicyclic epoxy resins obtained these one can be used alone or in appropriate combination of two or more.

The polyhydric phenol compound represented by the general formula (1) used as the curing agent of the present invention has the general formula (2):

[0011]

[Chemical 3]

(Wherein R ₁ represents an alkyl group having 1 to 12 carbon atoms), and a 2,6-diformyl-4-alkylphenol represented by the general formula (3):

[0013]

[Chemical 4]

(In the formula, R ₂ represents a hydrogen atom, a hydroxy group or an alkyl group having 1 to 4 carbon atoms.) Phenols can be easily subjected to a condensation reaction in the presence of an acid catalyst. Can be manufactured.

Specific examples of the 2,4-diformyl-4-alkylphenol represented by the general formula (2) include 2,6
-Diformyl-4-methylphenol, 2,6-diformyl-4-ethylphenol, 2,6-diformyl-4
-N-propylphenol, 2,6-diformyl-4-
i-Propylphenol, 2,6-diformyl-4-n
-Butylphenol, 2,6-diformyl-4-t-butylphenol, 2,6-diformyl-4-octylphenol, 2,6-diformyl-4-nonylphenol, 2,6-diformyl-4-dodecylphenol and the like can be mentioned. The 2,6-diformyl-4-alkylphenol is produced by oxidizing 2,6-dimethylol-4-alkylphenol in the presence of a catalyst such as palladium, platinum or manganese dioxide (Japanese Examined Patent Publication No. 60- 29371, Japanese Patent Publication No. 4-43059).

Specific examples of the phenols represented by the general formula (3) include phenol, resorcinol, pyrogallol and the like, cresols such as o-cresol, m-cresol and p-cresol, 2,3-xylenol,
2,4-xylenol, 2,5-xylenol, 2,6
Xylenol, 3,4-xylenol, 3,5-xylenol, and other xylenols, ethylphenol, n
-Propylphenol, i-propylphenol, n-
Examples thereof include various alkylphenols such as butylphenol and t-butylphenol. These phenols may be used alone or in combination of two or more.

The amount of phenols used is usually 2,6-
The amount is about 4 to 60 parts by mole, preferably about 8 to 32 parts by mole with respect to 1 part by mole of diformyl-4-alkylphenol. If it is less than 4 parts by mole, the production of high molecular weight substances will increase, and if it exceeds 60 parts by mole, the reaction rate will be slow and the reaction will take a long time, which is not preferable.

Examples of the acid catalyst used in the condensation reaction include organic acids, inorganic acids, metal salts and Lewis acids. Specifically, as organic acids, formic acid, oxalic acid, malonic acid,
Examples include succinic acid, acetic acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, paratoluenesulfonic acid, benzenesulfonic acid, phenolsulfonic acid, xylenesulfonic acid, trifluoromethanesulfonic acid, and the like, and inorganic acids include hydrochloric acid, sulfuric acid, nitric acid, Examples include perchloric acid, hydrobromic acid, phosphoric acid, etc., examples of metal salts include zinc acetate, zinc chloride, magnesium acetate, etc., examples of Lewis acids include boron trifluoride, titanium tetrachloride, aluminum chloride, etc. can give. Among these, it is preferable to use a strong acid catalyst such as p-toluenesulfonic acid or hydrochloric acid, since the selectivity is particularly good and the reaction rate can be controlled appropriately. The amount of the acid catalyst used is usually 0.001 to 10 parts by weight based on 100 parts by weight of 2,6-diformyl-4-alkylphenol because the reaction rate is appropriately controlled and the production of by-products can be suppressed. Degree, preferably 0.01 to 5
It is about part by weight.

In using the catalyst,
A suitable cocatalyst may be used. Specific examples of the cocatalyst include thioglycolic acid, thioglycerol, thiols such as benzenethiol. Among these,
It is preferable to use thioglycolic acid from the viewpoint of easy post-treatment and solubility. The amount of the co-catalyst used appropriately controls the reaction rate and suppresses the formation of by-products,
It is usually about 10 parts by weight or less, preferably about 0.001 to 5 parts by weight, based on 100 parts by weight of 2,6-diformyl-4-alkylphenol.

A solvent is not particularly required in the condensation reaction, but the reaction may be carried out using a suitable solvent. Specific examples of the solvent used include water, methyl alcohol, ethyl alcohol, isopropyl alcohol,
Examples thereof include alcohols such as butyl alcohol and isoamyl alcohol, glycol ethers such as ethyl cellosolve acetate, ethyl cellosolve and methyl cellosolve, and hydrocarbons such as hexane, cyclohexane, heptane, benzene, toluene and xylene.

The reaction temperature is usually about 20 to 200 ° C. The reaction rate is appropriately controlled, and the production of by-products can be suppressed.

After completion of the reaction, an alkaline substance is added to neutralize the acid catalyst (the acid catalyst and the cocatalyst when the cocatalyst is used). As the alkaline substance used,
Examples thereof include alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkali metal hydrogen carbonates, alkaline earth metal carbonates, ammonia, and organic amines. Among these, alkali metal hydroxides such as sodium hydroxide are preferable because they have few side reactions and are easy to handle. The alkaline substance may be added as it is, or may be added as an aqueous solution, but it is usually 0.
It may be added as an aqueous solution of about 1 to 50% by weight, preferably about 1 to 20% by weight.

After neutralization, an organic solvent or the like is added to the system to dissolve the reaction product, and the salt or metal ion produced by neutralization with water is washed. As the organic solvent, ethyl acetate, tetrahydrofuran, chloroform, methyl isobutyl ketone, benzene, toluene, xylene, hexane, heptane, cyclohexane and the like are preferable, and as water, ion exchanged water is preferable.

Thus, the polyhydric phenol compound represented by the above general formula (1) is obtained. In the reaction product, in addition to the polyhydric phenol compound represented by the general formula (1), It contains unreacted phenols. Such unreacted phenols can be easily removed by vacuum distillation, steam distillation or the like, and the polyhydric phenol compound represented by the general formula (1) can be easily isolated. Also,
In the case where the polyhydric phenol compound represented by the general formula (1) contains a high molecular weight compound obtained by condensing the polyhydric phenol compound with unreacted 2,6-diformyl-4-alkylphenol together with phenols and the like. There is. Such high molecular weight substances and the like can be removed by means of reprecipitation, recrystallization or the like, but the mixture can be used as it is as a curing agent.

The softening point of the curing agent containing the polyhydric phenol compound represented by the general formula (1) is usually 50 to 28.
0 ° C., preferably 70 to 150 ° C., and the hydroxyl value (hydroxyl group equivalent) is usually 200 to 700 (280 to 80),
It is preferably 400 to 600 (140 to 90).

In the obtained polyhydric phenol compound represented by the general formula (1), R ₁ has 1 to 12 carbon atoms,
Preferably, an alkyl group having 1 to 4 is represented, and R ₂ is a hydroxy group or an alkyl group having 1 to 4 carbon atoms. When R ₁ has more than 12 carbon atoms, the heat resistance of the cured product obtained when used as a curing agent for epoxy resin or the like is lowered, which is not preferable. When the carbon number of R ₂ exceeds 4,
It is not preferable because the reactivity with 2,6-diformyl-4-alkylphenol decreases. Further, the polyhydric phenol-based compound represented by the general formula (1) may use one kind of compounds having the same orientation as phenols, and R
A mixture of ₂ different phenols may be used. When two or more compounds having different orientations are used as phenols, a mixture of several kinds of polyhydric phenol compounds according to the orientation of each phenol is obtained.

In the present invention, a curing accelerator is used to accelerate the curing reaction between the polyfunctional epoxy resin and the curing agent containing the polyhydric phenol compound represented by the general formula (1). Examples of the curing accelerator include 1,8-diaza-bicyclo (5,4,0) undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol and the like. Tertiary amines; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole and other imidazoles; tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, phenylphosphine Organic phosphines such as; tetraphenylphosphonium tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, N-methylmorpholine tetraphenylborate Such as tetraphenyl boron salts such as rate and the like.

Next, the use ratio of each of the above-mentioned components of the epoxy resin composition of the present invention will be described. Usually, the curing agent is used such that the hydroxyl group equivalent of the curing agent is 0.5 to 1.5 equivalent to 1 equivalent of epoxy of the polyfunctional epoxy resin. If the proportion of the curing agent used is less than 0.5 equivalent, the curing rate will be slow, and if it exceeds 1.5 equivalents, a gelation reaction may occur, which is not preferable. Further, the curing accelerator is 0.1 parts by weight based on 100 parts by weight of the polyfunctional epoxy resin.
It is used in a proportion of 1 to 5 parts by weight. If the proportion of the curing accelerator used is less than 0.1 part by weight, the curing acceleration effect is almost zero.
If the amount is more than parts by weight, the cured product tends to impair properties such as heat resistance and mechanical properties, which is not preferable.

In addition, various solvents, fillers, mold release agents, surface treatment agents, flame retardants and the like may be added to the epoxy resin composition as required. The epoxy resin composition is
Usually, it is prepared by heating and mixing using a roll, a kneader or the like.

[0030]

The cured product of the epoxy resin composition of the present invention has a high cross-linking density and a high glass transition point, and is therefore excellent in high heat resistance. Since the epoxy resin composition of the present invention has excellent heat resistance, for example, molded products (sealing materials for semiconductors, transfer molded products of various electronic parts,
Insulation materials for communication equipment, brake pistons and timing gears for automobile parts, household products such as kettles and iron handles, adhesives (copper adhesives for printed circuit boards, structural materials for automobiles and aircraft) Adhesives), laminated products (printed circuits, automobile and aircraft structural materials and fuel tanks,
Pipes, storage tanks, pressure vessels, etc.), paints (automotive paints, solvent-free paints, high-solid paints, powder paints, water-based emulsion paints), baking paints (protective paints for chemical equipment, various linings, electrical insulating varnishes) It can be used for various purposes.

[0031]

EXAMPLES The present invention will be described in more detail with reference to production examples, examples and comparative examples, but the present invention is not limited to these examples.

Production Example 1 In a reaction vessel connected with a water separator connected with a stirrer, a reflux condenser, a mercury thermometer and a nitrogen gas inlet tube, 2,6-
Diformyl-4-methylphenol 16.42 g, phenol 304.19 g, and toluene 320.6 ml were charged and stirred at room temperature under a nitrogen stream, and when the system became uniform, 0.126 ml of cocatalyst thioglycolic acid and para of catalyst. 0.19 g of toluenesulfonic acid monohydrate was added.
Then, heating was started by an oil bath equipped with a heater installed in the lower part of the container, and the reaction was carried out for about 5 hours while removing azeotropic water under reflux. After completion of the reaction, heating was stopped and when the temperature reached around 80 ° C., 3 ml of a 4% aqueous sodium hydroxide solution was added to neutralize the catalyst. After cooling the reaction solution to room temperature, put it in a separatory funnel together with about 1500 ml of methyl isobutyl ketone, and mix with about 800 ml of deionized water.
Washed twice. After that, the solvent and phenol were removed by vacuum distillation, and the phenol was completely removed by steam distillation. After crushing the resin obtained here with a crusher,
Dry in a vacuum dryer (5 mmHg / 80 ° C, 6 hours),
Polyphenolic compound (hereinafter referred to as compound A) 4
9.9 g was obtained. Yield 98.9% (hereinafter, simply referred to as the yield, with 100% as the weight in the case where 4-fold mole of phenol has reacted with 2,6-diformyl-4-methylphenol). The softening point of Compound A is 139-143 ° C,
The hydroxyl equivalent was 110 (hydroxyl value was 509).

The softening point was measured by a trace melting point measuring device (manufactured by Yanaco Instruments Development Laboratory Co., Ltd.) and visually observing the sample sandwiched between the glass plates on the heating stage with a 10 × magnifying glass. The measurement was performed. The hydroxyl value is JIS
The measurement was performed according to K 0070, and the hydroxyl equivalent was calculated from the result by the following formula. Hydroxyl equivalent = {56.
11 (molecular weight of potassium hydroxide) / hydroxyl value} × 100
0.

Production Example 2 Reaction was carried out in the same manner as in Production Example 1 except that 349.54 g of orthocresol was used in place of 304.19 g of phenol and the amount of toluene used was changed to 366.6 ml. Polyphenolic compound (hereinafter referred to as compound B
55.8 g was obtained (yield 99.5%). In addition,
Compound B has a softening point of 132-137 ° C. and a hydroxyl equivalent of 12
It was 3 (hydroxyl value is 455).

Production Example 3 2,6-diformyl-4 was placed in the same reaction vessel as in Production Example 1.
-Methylphenol 16.42g, orthocresol 6
5.54 g of toluene and 196.0 ml of toluene were charged and stirred at room temperature under a nitrogen stream. When the system became uniform, 0.126 ml of thioglycolic acid as a cocatalyst and 0.190 g of paratoluenesulfonic acid monohydrate as a catalyst were added. added. Then
Start heating with an oil bath equipped with a heater installed at the bottom of the container, and remove the azeotropic water under reflux while removing about 2
Allowed to react for hours. Further phenol 114.07 here
g was added and the reaction was carried out in the same manner for 6 hours. After completion of the reaction, heating was stopped and when the temperature reached around 80 ° C., 6.00 ml of 4% sodium hydroxide aqueous solution was added to neutralize the catalyst.
After the reaction solution was cooled to room temperature, it was put into a separating funnel together with about 1500 ml of methyl isobutyl ketone and washed 3 times with about 800 ml of deionized water. Then, the solvent and phenols were removed by vacuum distillation, and the phenols were completely removed by steam distillation. The resin obtained here was pulverized with a pulverizer and then dried under reduced pressure (5 mmHg / 80
After drying at 60 ° C. for 6 hours, 52.46 g of a polyhydric phenol compound (hereinafter referred to as compound C) was obtained (yield 93.
6%). The softening point of compound C is 104-106 ° C,
The hydroxyl equivalent was 113 (hydroxyl value was 495).

Preparation Example 4 In Preparation Example 3, instead of 65.54 g of orthocresol, 32.77 g of orthocresol and 32.77 g of metacresol were used, and the amount of toluene used was 163.3.
Reaction was performed in the same manner as in Production Example 3 except that the amount was changed to ml, and a polyhydric phenol compound (hereinafter, referred to as compound D) 52.7.
6 g was obtained (yield 94.1%). The softening point of compound D is 94-98 ° C., the hydroxyl equivalent is 126 (the hydroxyl value is 44
It was 4).

Example 1 Epoxy resin (YDCN702P, manufactured by Tohto Kasei Co., Ltd.,
After pre-mixing 100 g of epoxy equivalent 205) with 50 g of the compound A obtained in Production Example 1 as a curing agent at 110 ° C. for 2 to 4 minutes, 2 g of triphenylphosphine as a curing accelerator, and an ester wax (manufactured by Hoechst) ,
Wax OP) 2 g, carbon black (Mitsubishi Chemical Co., Ltd., MA-100) 0.5 g, and silica (Tatsumori Co., Ltd., CRS-1101-01) 350 g were added,
Using a mixing roll 6 × 12 inch (manufactured by Inoue Seisakusho Co., Ltd.), heating roll kneading was performed at 90 ° C. for 6 to 10 minutes. Then, pulverize and adjust the particle size with a compression molding machine (hydraulic molding machine, MF-O type, manufactured by Marushichi Iron Works Co., Ltd.)
Compression molding was performed under the conditions of 70 ° C., 280 kg / cm ² , and 4 minutes, and further cured at 175 ° C. for 8 hours to obtain a cured product.

Examples 2 to 4 and Comparative Example 1 A cured product molded in the same manner as in Example 1 except that the type of the curing agent was changed as shown in Table 1 was obtained.

The molded cured products obtained in the examples and comparative examples were subjected to the following tests to measure various physical properties. The results are shown in Table 1.

(Hot plate gel time) The time (sec) until the molding material gelled on a hot plate at 170 ° C. was measured.

(Volume resistivity) Disc (100 mmΦ × 2
mm) in the cured product at room temperature
JIS K 6 using an ISTANCE METER 4329-A type (manufactured by Hewlett Packard)
911 (unit: × 10 ¹⁵ Ωcm).

(Bending strength) Autograph DSS at normal temperature
-2000 (manufactured by Shimadzu Corporation)
Measured according to K6911 (unit: kgf / mm
² ).

(Glass transition point) TMA-30 type (Co., Ltd.)
A temperature / linear expansion curve was measured using a device manufactured by Shimadzu Corporation, and the temperature at the bending point was taken as the glass transition point (° C).

[0044]

[Table 1]

From the results of Table 1, compounds A to
The cured product of the epoxy resin composition of the present invention using D has a higher glass transition point (excellent heat resistance) than the cured product of the epoxy resin composition using the conventional novolac phenol resin. Is recognized. Regarding other performances, it is recognized that they have equivalent or higher performances. In Table 1, * 1 represents a novolac phenol resin (Barkham TD2121, manufactured by Dainippon Ink and Chemicals, Inc., hydroxyl equivalent 103).

Claims (1)

[Claims] 1. A polyfunctional epoxy resin, represented by the general formula (1): (In the formula, R ₁ represents an alkyl group having 1 to 12 carbon atoms, R ₂ represents a hydrogen atom, a hydroxy group or an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 1 or 2.) An epoxy resin composition containing a curing agent containing a polyhydric phenol compound as a main component, and a curing accelerator.