JPH08208802A - Epoxy resin, epoxy resin composition and cured product thereof - Google Patents

Abstract

PURPOSE: To obtain an epoxy resin having a specific molecular structure, giving excellent heat resistance, water resistance and mechanical strengths, and useful as a molding material, etc. CONSTITUTION: The resin of formula I (n is an average number consisting of 0-10; P, R are H, halogen, 1-8C alkyl, aryl; G is glycidyl). This resin is obtained e.g. by condensing a compound of formula II (X is halogen, OH, lower alkoxy) with a phenol compound such as phenol in the presence of an acidic catalyst such as p-toluenesulfonic acid in a solvent such as methylisobutylene at 40-80 deg.C for 1-8hrs and subsequently reacting the obtained compound of formula III with an epihalohydrin in the presence of an alkali metal oxide such as NaOH at 20-120 deg.C for 1-10hrs.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin and an epoxy resin composition which give a cured product having excellent heat resistance, water resistance and mechanical strength.

[0002]

BACKGROUND OF THE INVENTION Epoxy resins, when cured with various curing agents, generally become cured products having excellent mechanical properties, water resistance, chemical resistance, heat resistance, electrical properties, etc., and are used as adhesives and paints. It is used in a wide range of fields such as laminated boards, molding materials, and casting materials. Conventionally, liquid and solid bisphenol A type epoxy resins obtained by reacting bisphenol A with epichlorohydrin have been used as the most industrially used epoxy resins. Other liquid bisphenol A type epoxy resin to tetrabromobisphenol
A flame-retardant solid epoxy resin obtained by reacting the resin A is industrially used as a general-purpose epoxy resin.

[0003]

However, the general-purpose epoxy resin as described above has a drawback in that as the molecular weight increases, the toughness of the cured product obtained by curing it increases, but the heat resistance decreases. Further, although a cured product obtained by mixing a polyfunctional epoxy resin such as cresol novolac epoxy resin in order to compensate for the decrease in heat resistance has high heat resistance, it has a drawback that toughness decreases and water absorption increases. . On the other hand, with the recent remarkable development of the electronic industry and the like, the heat resistance, water resistance and mechanical strength (eg toughness) required for electrical insulating materials used for these have become increasingly severe, and these characteristics are excellent. The advent of epoxy resins has long been awaited. Further, as an epoxy resin satisfying these characteristics, JP-A-5-11
No. 7350 describes an epoxy resin having a biphenyl skeleton, and the epoxy resin specifically disclosed therein has excellent water resistance and mechanical strength, but has two functional groups, and therefore has heat resistance. Is not enough.

[0004]

In view of these circumstances, the present inventors have earnestly studied for an epoxy resin which gives a cured product having excellent heat resistance, water resistance and mechanical strength, and as a result, have a specific molecular structure. The present invention has been completed by finding that an epoxy resin imparts excellent heat resistance, water resistance and mechanical strength to its cured product.

That is, the present invention is based on the equation (1)

[0006]

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(In the formula, n represents an average value and takes a value of 0 to 10. P and R are a hydrogen atom, a halogen atom and a carbon number of 1 to 8).
Represents an alkyl group or an aryl group of
R may be the same as or different from each other. G represents a glycidyl group. ) Epoxy resin represented by

(2) An epoxy resin composition containing the epoxy resin and the curing agent described in (1) above, and optionally a curing accelerator, and (3) a curing obtained by curing the epoxy resin composition described in (2) above. It is intended to provide things.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A compound represented by the formula (1) is, for example, a compound represented by the formula (2)

[0010]

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(In the formula, n, P and R have the same meanings as in formula (1).)

It can be obtained by carrying out the reaction between the compound represented by and epihalohydrin in the presence of an alkali metal hydroxide.

The compound represented by the formula (2) is represented by, for example, the formula (3)

[0014]

[Chemical 4]

(Wherein X represents a halogen atom, a hydroxyl group or a lower alkoxy group, and R represents the same meaning as in formula (1)) and a phenol compound in the presence of an acid catalyst. It can be obtained by carrying out a condensation reaction with.

In X of the formula (3), halogen atom is chlorine atom, bromine atom, etc., lower alkyl group is methyl group, ethyl group, t-butyl group, etc., and lower alkoxy group is methoxy group, ethoxy group. And the like are mentioned as preferable groups.

Here, the phenols include aromatic compounds having one phenolic hydroxyl group in one molecule, and specific examples of the compounds that can be used include phenol, cresol,
Various o-, m-, p-isomers of alkylphenols such as ethylphenol, n-propylphenol, isobutylphenol, t-butylphenol, octylphenol, nonylphenol, xylenol, methylbutylphenol, di-t-butylphenol, or vinylphenol, allyl. Examples include various o-, m- and p-isomers of phenol, propenylphenol and ethynylphenol, cycloalkylphenols such as cyclopentylphenol, cyclohexylphenol and cyclohexylcresol, and substituted phenols such as phenylphenol. These phenols are 1
Only one kind may be used, or two or more kinds may be used in combination.

When carrying out the condensation reaction, the amount of the phenols used is preferably 0.5 to 20 mol, particularly preferably 2 to 15 mol, per 1 mol of the compound represented by the formula (3).

In the above condensation reaction, it is preferable to use an acid catalyst, and various acid catalysts can be used, but inorganic or organic acids such as hydrochloric acid, sulfuric acid, p-toluenesulfonic acid and oxalic acid, and boron trifluoride. Lewis acids such as anhydrous aluminum chloride and zinc chloride are preferable, and p-toluenesulfonic acid, sulfuric acid and hydrochloric acid are particularly preferable. The amount of these acid catalysts used is not particularly limited, but is not limited to the formula (3).
It is preferable to use 0.1 to 30% by weight of the compound represented by.

The condensation reaction can be carried out without a solvent or in the presence of an organic solvent. Specific examples of the case of using an organic solvent include toluene, xylene, and methyl isobutyl ketone. The amount of the organic solvent used is preferably 50 to 300% by weight, and particularly preferably 100 to 250% by weight, based on the total weight of the raw materials charged. The reaction temperature is preferably 40 to 180 ° C., and the reaction time is 1 to 8
Time is preferred.

After completion of the reaction, a washing treatment is carried out until the pH value of the washing liquid becomes 3 to 7, preferably 5 to 7. In this case, if necessary, sodium hydroxide, an alkali metal hydroxide such as potassium hydroxide, calcium hydroxide, an alkaline earth metal hydroxide such as magnesium hydroxide, ammonia, sodium dihydrogen phosphate and further diethylenetriamine,
Various basic substances such as triethylenetetramine, aniline, and organic amines such as phenylenediamine may be used as the neutralizing agent for treatment. Washing with water may be performed according to a conventional method. For example, water in which the above-mentioned neutralizing agent is dissolved is added to the reaction mixture, and the liquid separation and extraction operation is repeated.

After washing with water, the unreacted dihydroxybenzenes and solvent are distilled off under reduced pressure to concentrate the product to obtain the compound represented by the formula (2).

As a method for obtaining the epoxy resin of the present invention from the compound represented by the formula (2), a known method can be adopted. For example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added in advance to a mixture of the compound represented by the formula (2) obtained above and excess epihalohydrin such as epichlorohydrin or epibromhydrin, Or 1 to 1 at a temperature of 20 to 120 ° C. while adding
The epoxy resin of the present invention can be obtained by reacting for 0 hours.

In the reaction for obtaining the epoxy resin of the present invention, an aqueous solution of the alkali metal hydroxide may be used, in which case an aqueous solution of the alkali metal hydroxide is continuously added to the reaction system. Water and epihalohydrin may be continuously distilled off under reduced pressure or normal pressure, and the liquid may be further separated to remove water and the epihalohydrin may be continuously returned to the reaction system.

Further, a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide, trimethylbenzylammonium chloride, etc. is added as a catalyst to a dissolved mixture of the compound represented by the formula (2) and epihalohydrin, and the mixture is added at 50 to 150 1 to ℃
A solid or aqueous solution of an alkali metal hydroxide is added to the halohydrin ether compound of the compound of formula (2) obtained by reacting for 5 hours, and the mixture is reacted at a temperature of 20 to 120 ° C. for 1 to 10 hours to dehydrohalogenate ( A method of ring closure) may be used.

Usually, the amount of epihalohydrin used in these reactions is usually 1 to 20 mol, preferably 2 to 10 mol per 1 equivalent of the hydroxyl group of the compound represented by the formula (2). The amount of the alkali metal hydroxide used is 0.8 to 15 mol, preferably 0.9 to 11 mol, based on 1 equivalent of the hydroxyl group of the compound represented by the formula (2). The amount of the quaternary ammonium salt used is usually 1 to 10 g, preferably 2 to 8 g, based on 1 equivalent of the hydroxyl group of the compound of formula (2). Furthermore, in order to make the reaction proceed smoothly, methanol,
In addition to alcohols such as ethanol, aprotic polar solvents such as dimethyl sulfone and dimethyl sulfoxide are preferably added to carry out the reaction.

When alcohols are used, the amount used is 2 to 20% by weight, preferably 4 to 15% by weight, based on the amount of epihalohydrin. When an aprotic polar solvent is used, it is 5 to 100 relative to the amount of epihalohydrin.
%, Preferably 10 to 90% by weight.

After washing the reaction products of these epoxidation reactions with or without washing with water, under heating and reduced pressure, 110 to 250 ° C.,
Epihalohydrin and added solvent are removed at a pressure of 10 mmHg or less. Further, in order to obtain an epoxy resin having less hydrolyzable halogen, the obtained epoxy resin is dissolved in a solvent such as toluene or methyl isobutyl ketone, and an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added. In addition, it is possible to carry out a further reaction to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is preferably 0.01 to 0. 1 with respect to 1 equivalent of the hydroxyl group of the compound represented by the formula (2) used for the epoxidation.
3 mol, particularly preferably 0.05 to 0.2 mol.
The reaction temperature is 50 to 120 ° C., and the reaction time is usually 0.5 to 2
Time.

After the completion of the reaction, the produced salt is removed by filtration, washing with water and the like, and the solvent such as toluene and methyl isobutyl ketone is distilled off under heating and reduced pressure to obtain the epoxy resin of the present invention.

The epoxy resin composition of the present invention can be obtained by uniformly mixing the epoxy resin of the present invention, a curing agent, and optionally a curing accelerator. In the epoxy resin composition of the present invention, an epoxy resin other than the epoxy resin of the present invention can be used in combination as the epoxy resin. When another epoxy resin is used in combination, the proportion of the epoxy resin of the present invention in the total epoxy resin is preferably 20% by weight or more. In the epoxy resin composition of the present invention, amine compounds, acid anhydride compounds, amide compounds, phenol compounds and the like can be used as the curing agent. Specific examples of the curing agent that can be used include diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, a polyamide resin synthesized from a dimer of linolenic acid and ethylenediamine, phthalic anhydride, trianhydride. Mellitic acid, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic acid anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolac, and modified products thereof. Examples thereof include imidazole, BF ₃ -amine complex, and guanidine derivative. Further, the compound represented by the formula (2) used as a raw material of the epoxy resin of the present invention can also be used as a curing agent. These curing agents may be used alone or in combination of two or more.

The amount of these curing agents used is preferably 0.7 to 1.2 equivalents based on 1 equivalent of the epoxy groups of the epoxy resin. If the amount is less than 0.7 equivalent or more than 1.2 equivalent to 1 equivalent of the epoxy group, the curing may be incomplete and good cured physical properties may not be obtained.

When using the above-mentioned curing agent, a curing accelerator may be used in combination. Specific examples of the curing accelerator that can be used include 2-methylimidazole, 2-ethylimidazole, imidazoles such as 2-ethyl-4-methylimidazole, 2- (dimethylaminomethyl) phenol,
1,8-diaza-bicyclo (5,4,0) undecene-
And tertiary amines such as 7; phosphines such as triphenylphosphine; and metal compounds such as tin octylate. The curing accelerator may be used in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the epoxy resin.
Furthermore, to the epoxy resin composition of the present invention, various compounding agents such as a filler such as silica, alumina and talc, a silane coupling agent, a release agent and a pigment can be added, if necessary.

The epoxy resin composition of the present invention is obtained by uniformly mixing the components. The epoxy resin composition of the present invention in which the epoxy resin of the present invention, a curing agent and, if necessary, a curing accelerator are blended can be easily made into a cured product by the same method as a conventionally known method. For example, the epoxy resin of the present invention and a curing agent, a filler and other additives are sufficiently mixed by using an extruder, a kneader, a roll or the like, if necessary, until they are homogeneous, and the epoxy resin of the present invention is obtained. A cured product can be obtained by obtaining a resin composition, molding the epoxy resin composition after melting using a casting or transfer molding machine, and then heating at 80 to 200 ° C. for 2 to 10 hours. .

Further, the epoxy resin composition of the present invention is dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone and the like to prepare glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper and the like. A prepreg obtained by impregnating the base material with heat and drying can also be hot-press molded to obtain a cured product.

In this case, the diluting solvent is used in an amount of usually 10 to 70% by weight, preferably 15 to 65% by weight in the mixture of the epoxy resin composition of the present invention and the diluting solvent.

The cured product thus obtained is excellent in heat resistance, water resistance and mechanical strength, so that it can be used in a wide range of fields where heat resistance and water resistance are required. Specifically, it is useful as any electric / electronic material such as a sealing material, a laminated plate, an insulating material, and the like. It can also be used in fields such as molding materials, adhesives and paints.

[0037]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples and Comparative Examples. In the following, “parts” means “parts by weight” unless otherwise specified.

Example 1 A flask equipped with a thermometer, a dropping funnel, a condenser and a stirrer was charged with the following formula (4).

[0039]

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242 parts of the compound represented by: and phenol 2
82 parts were charged, and the mixture was stirred at room temperature while blowing nitrogen. 2.8 parts of p-toluenesulfonic acid (monohydrate) was slowly added while paying attention to heat generation so that the liquid temperature did not exceed 50 ° C. After that, it was heated to 110 ° C. in an oil bath and reacted for 2 hours. After the reaction was completed, 1000 ml of methyl isobutyl ketone was further added, and the mixture was transferred to a separating funnel and washed with water. After washing with water until the washing water became neutral, the solvent and unreacted substances were removed from the organic layer under heating and reduced pressure to obtain 299 parts of a resinous compound having a softening point of 108 ° C. Using tetrahydrofuran as a solvent for this compound, GPC analysis, mass spectrum (F
As a result of analysis by AB-MS) analysis, this compound has the following formula (5).

[0041]

[Chemical 6]

It was confirmed to be a compound represented by When the hydroxyl equivalent is calculated from the result of GPC analysis, it is 22
It became 8 g / eq. The average value of n was 2.1.

Then, 228 parts of the compound obtained in the above reaction and epichlorohydrin 370 were charged in a flask equipped with a thermometer, a condenser and a stirrer while purging with nitrogen gas.
And 92.5 parts of dimethyl sulfoxide were charged and dissolved. Further, the mixture was heated to 50 ° C., 40.4 parts of flaky sodium hydroxide (purity 99%) was added portionwise over 90 minutes,
Then, the mixture was further reacted at 60 ° C. for 2 hours and at 70 ° C. for 1 hour. After completion of the reaction, dimethyl sulfoxide and epichlorohydrin were distilled off under reduced pressure by heating at 130 ° C.
8 parts of methyl isobutyl ketone was added and dissolved.

Further, this solution of methyl isobutyl ketone is heated to 70 ° C. and a 30% by weight aqueous solution of sodium hydroxide 1
After adding 0 part and reacting for 1 hour, washing with water was repeated 3 times to make the pH neutral. Further, the water layer is separated and removed, and methyl isobutyl ketone is distilled off from the oil layer under heating and reduced pressure by using a rotary evaporator to obtain the following formula (6).

[0045]

[Chemical 7]

267 parts of the epoxy resin (A) of the present invention represented by the formula (G represents a glycidyl group and the average value of n is 2.1) was obtained. The obtained epoxy resin had a softening point of 85.3 ° C. and an epoxy equivalent of 295 g / eq.

Example 2 The reaction was performed in the same manner as in Example 1 except that 432 parts of o-cresol was used instead of phenol, and the softening point was 101.5.
337 parts of a resinous compound at 0 ° C. was obtained. This compound was analyzed by GPC analysis and mass spectrum (FAB-MS) analysis using tetrahydrofuran as a solvent,
This compound has the following formula (7)

[0048]

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It was confirmed to be a compound represented by: When the hydroxyl equivalent is calculated from the result of GPC analysis, it is 22
It became 9 g / eq. The average value of n was 1.1. Next, an epoxidation reaction was carried out in the same manner as in Example 1 except that 229 parts of the compound represented by the formula (7) was used, and the following formula (8)

[0050]

[Chemical 9]

273 parts of the epoxy resin (B) of the present invention represented by the formula (wherein G represents a glycidyl group and the average value of n is 1.1) was obtained. The obtained epoxy resin had a softening point of 82.2 ° C. and an epoxy equivalent of 293 g / eq.

Comparative Example 1 The following formula (9) was used according to Example 1 of JP-A-5-117350.

[0053]

[Chemical 10]

A compound represented by

Then, using the compound of formula (9), an epoxy resin (C) was obtained according to Example 2 of the publication.

Examples 3 to 4, Comparative Example 2 Epoxy resins (A) and (B) of the present invention, the comparative epoxy resin (C), phenol novolac as a curing agent (hydroxyl equivalent 106 g / eq, softening point 80). 2 ° C.), triphenylphosphine (TPP) was used as a curing accelerator, and compounded in the composition shown in the composition column of the composition in Table 1 to obtain 7
Knead with a roll for 15 minutes at 0 ℃, 150 ℃, molding pressure 50
Transfer molding was performed at 180 kg / cm ² for 180 seconds, and thereafter, curing was performed at 160 ° C. for 2 hours and then at 180 ° C. for 8 hours to prepare a test piece, and the glass transition point and water absorption were measured. The results are shown in Table 1. The conditions for measuring the glass transition point, water absorption and bending strength are as follows. Further, in the table, the numerical value in the column of composition of formulation shows parts by weight.

Glass transition temperature thermomechanical measuring device (TMA): manufactured by Vacuum Riko Co., Ltd. TM-
7000 Temperature rising rate: 2 ° C / min Water absorption rate Test piece (cured product): Diameter 50 mm Thickness 3 mm Disc Weight increase rate (%) after boiling in 100 ° C water for 24 hours Bending strength According to JIS K-6911 Measurement

[0058]

Table 1 Example 3 Example 3 Example 4 Comparative Example 2 Composition of the compound Epoxy resin (A) 100 Epoxy resin (B) 100 Epoxy resin (C) 100 (Epoxy equivalent (g / eq)) 295 293 292 Phenol Novolac 35.9 36.2 36.3 TPP 1 1 1 Physical properties of cured product Glass transition point (℃) 161 160 152 Water absorption rate (%) 0.73 0.71 0.80 Bending strength (Kg / mm ² ) 13.8 13.5 12.4

From Table 1, the cured product of the epoxy resin of the present invention showed higher glass transition point, lower water absorption and higher mechanical strength than the known cured product of epoxy resin having a biphenyl skeleton.

[0060]

INDUSTRIAL APPLICABILITY The epoxy resin of the present invention can provide a cured product having excellent heat resistance, water resistance and mechanical strength, and can be used as a molding material, a casting material, a laminating material, a paint, an adhesive, Very useful for a wide range of applications such as resists.

Claims (3)

[Claims] 1. A formula (1): (In the formula, n represents an average value and takes a value of 0 to 10. P, R
Represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group, and each P and R may be the same or different from each other. G represents a glycidyl group. ) Epoxy resin represented by. 2. An epoxy resin composition containing the epoxy resin according to claim 1 and a curing agent, and optionally a curing accelerator. 3. A cured product obtained by curing the epoxy resin composition according to claim 2.