JPH08269168A - Epoxy resin, epoxy resin composition and its cured product - Google Patents

Abstract

PURPOSE: To obtain an epoxy resin expressed by a specific formula, giving a cured product having excellent heat-resistance, water resistance and mechanical strength and useful as a molding material, etc. CONSTITUTION: This epoxy resin is expressed by formula I [(n) is a positive number showing the average value; R is a halogen, a 1-8C alkyl or an aryl; G is glycidyl; X is H or G; 5-95% of (n) X groups are G; Y is a 5 to 8-membered cycloalkane residue which may have substituents on the ring]. The resin can be produced e.g. by reacting a compound of formula II with an epihalohydrin in the presence of an alkali metal hydroxide and reacting the alcoholic OH of the produced resin of formula III with an epihalohydrin in the presence of an alkali metal hydroxide such as NaOH at 20-100 deg.C for 1-20hr.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art 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. It is used in a wide range of fields such as laminates, 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 bromine-containing 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 that the heat resistance of the cured product obtained by using the general-purpose epoxy resin decreases as the molecular weight increases. Further, when a polyfunctional epoxy resin such as an orthocresol novolac epoxy resin is added to a general-purpose epoxy resin, the heat resistance of the cured product is improved, but the water resistance and toughness are deteriorated.

[0004]

In view of these circumstances, the present inventors have earnestly studied for an epoxy resin which gives a cured product excellent in heat resistance, water resistance and toughness, and as a result, a specific epoxy resin is a cured product thereof. In the present invention, they have found that they impart excellent heat resistance, water resistance and toughness, and have completed the present invention.

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

[0006]

Embedded image

(In the formula, n represents an average value and represents a positive number. R
Represents a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group, and each R may be the same or different. G represents a glycidyl group. X represents a hydrogen atom or a glycidyl group, and each X may be the same as or different from each other, but 5 to 95% of n Xs present are glycidyl groups. Y represents a residue of a cycloalkane having 5 to 8 ring members which may be ring-substituted, and when the ring is substituted, the substituent is an alkyl group or aryl group having 1 to 4 carbon atoms. ) Epoxy resin represented by

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

Although n in the formula (1) represents a positive number, it is preferably in the range of 0.01 to 5. The epoxy resin represented by the formula (1) has the formula (2)

[0010]

Embedded image

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

It can be obtained by reacting the alcoholic hydroxyl group of the epoxy resin represented by the formula with epihalohydrin in the presence of an alkali metal hydroxide.

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

[0014]

[Chemical 4]

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

It can be obtained by reacting the compound represented by ## STR1 ## with epihalohydrin in the presence of an alkali metal hydroxide.

Specific examples of the compound represented by the formula (3) include the following formula (4)

[0018]

Embedded image

Alternatively, the following equation (5)

[0020]

[Chemical 6]

Alternatively, the following equation (6)

[0022]

[Chemical 7]

Examples thereof include compounds represented by, but are not limited to these.

Further, in the formula (1), the ratio in which n Xs are glycidyl groups (hereinafter referred to as glycidylation rate) is 5
% And 95% or less, the reaction of the epoxy resin obtained by the above-mentioned method with epihalohydrin is dimethyl sulfoxide, quaternary ammonium salt or 1,3.
It can be obtained by carrying out in the coexistence of dimethyl-2-imidazolidinone and an alkali metal hydroxide. The present inventors have found that the alcoholic hydroxyl group of the epoxy resin obtained by this method is more reactive than that of general alcohols, and for example, dimethyl sulfoxide, quaternary ammonium or 1,3-dimethyl-2-imidazolidinium. Surprisingly, the coexistence of non-alkali metal hydroxide selectively reacts with the newly added epihalohydrin-derived epoxy group only in the reaction between the alcoholic hydroxyl group and the epoxy group present in the reaction mixture. Can be done
Furthermore, the alcoholic hydroxyl group of the epoxy resin represented by the formula (1) can be epoxidized to a desired ratio by adjusting the amount of the alkali metal hydroxide.

The details of the present invention will be described below.

As a method for obtaining the epoxy resin 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 to a dissolved mixture of the compound represented by the formula (3) and an excess of epihalohydrin, or 20 to 120 ° C. while being added.
It can be obtained by reacting at the temperature of 1 to 20 hours. In the above reaction, an aqueous solution of the alkali metal hydroxide may be used, and in that case, an aqueous solution of the alkali metal hydroxide is continuously added to the reaction mixture and continuously under reduced pressure or under normal pressure. Alternatively, water and epihalohydrin may be distilled off, the liquid may be separated, water may be removed, and epihalohydrin may be continuously returned to the reaction mixture.

Further, a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide or trimethylbenzylammonium chloride 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 ° C. The solid or aqueous solution of an alkali metal hydroxide is added to the halohydrin etherified product of the compound of formula (2) obtained by the reaction in step (1), and the mixture is reacted again at a temperature of 20 to 120 ° C. for 1 to 20 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 1.5 to 10 mol, based on 1 equivalent of the hydroxyl group of the compound represented by the formula (2).
It is 10 mol. The amount of the alkali metal hydroxide used is usually 0. 1 with respect to 1 equivalent of the hydroxyl group of the compound represented by the formula (2).
It is 8 to 1.5 mol, preferably 0.9 to 1.1 mol. In order to allow the reaction to proceed smoothly, it is preferable to carry out the reaction by adding alcohols such as methanol and ethanol, as well as an aprotic polar solvent such as dimethyl sulfone and dimethyl sulfoxide.

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

The epoxy resin of the present invention represented by the formula (2) is obtained by washing the reaction products of these epoxidation reactions with or without washing with water under reduced pressure with heating to remove epihalohydrin and other added solvents. be able to.

Further, by reacting the epoxy resin thus obtained with the compound represented by the formula (3) in the presence of a basic catalyst, a high molecular weight compound having a larger n value in the formula (2) is obtained. An epoxy resin can be obtained. In this polymerization reaction, the charging ratio of each component is such that the hydroxyl equivalent of the compound represented by the formula (3) is 0 to 0.9 with respect to 1 equivalent of the epoxy group of the low molecular weight epoxy resin obtained in the above reaction.
It is preferably an equivalent amount, and particularly preferably 0 to 0.85 equivalent amount.

Examples of the basic catalyst include triphenylphosphine, sodium hydroxide, potassium hydroxide, 4
Examples thereof include primary ammonium salts and imidazoles, and the amount thereof is preferably 0.001 to 1.0% by weight with respect to 1 equivalent of the low molecular weight epoxy resin obtained by the above reaction,
In particular, 0.005 to 0.5% by weight is preferable. When a solvent is used, methyl isobutyl ketone, toluene and the like can be given as specific examples of the solvent that can be used. The reaction temperature is preferably 60 to 200 ° C, particularly preferably 70 to 190 ° C. The reaction time is 0.5 to 20 hours, especially 1 to 1
5 hours is preferred. In this way, the epoxy resin represented by the formula (2) can be obtained.

The reaction between the alcoholic hydroxyl group of the epoxy resin of the formula (2) and epihalohydrin is carried out by dimethyl sulfoxide or a quaternary ammonium salt or 1,3-dimethyl-
It can be carried out by adjusting the amount of the alkali metal hydroxide in the presence of 2-imidazolidinone and the alkali metal hydroxide. At that time, alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene and xylene, ketones such as methyl isobutyl ketone and methyl ethyl ketone, and cyclic and ether compounds such as tetrahydrofuran may be used together as a solvent.

The amount of dimethyl sulfoxide or 1,3-dimethyl-2-imidazolidinone used is preferably 5 to 300% by weight based on the epoxy resin used as a raw material. When it exceeds 300% by weight with respect to the raw material epoxy resin, the effect of increasing the amount is almost lost, but the volume efficiency is deteriorated, which is not preferable.

Specific examples of the quaternary ammonium salt that can be used include tetramethylammonium chloride, tetramethylammonium bromide, trimethylammonium chloride, etc. The amount used is the alcoholic hydroxyl group to be epoxidized in the epoxy resin used as the raw material. 0.3 to 50 g is preferable for 1 equivalent. If the amount of the hydroxyl group to be epoxidized is less than 0.3 g based on 1 equivalent, the reaction between the alcoholic hydroxyl group of the epoxy resin used as a raw material and the epihalohydrin is delayed, which requires a long reaction time, which is not preferable. When the amount exceeds 50 g per equivalent of the alcoholic hydroxyl group to be epoxidized, the effect of increasing the amount is almost lost but the cost becomes high, which is not preferable.

The amount of epihalohydrin used may be equal to or more than 1 equivalent of the alcoholic hydroxyl group to be epoxidized in the epoxy resin used as a raw material. However, when the amount exceeds 30 times the equivalent of the hydroxyl group to be epoxidized, the effect of increasing the amount is almost lost and the volume efficiency is deteriorated, which is not preferable.

As the alkali metal hydroxide, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide and the like can be used, but sodium hydroxide is preferred. The amount of the alkali metal hydroxide used may be 1 to 2 times equivalent to 1 equivalent of the alcoholic hydroxyl group to be epoxidized in the epoxy resin used as a raw material. The alkali metal hydroxide may be a solid or an aqueous solution. Further, when an aqueous solution is used, the reaction can be carried out during the reaction while distilling the water in the reaction mixture out of the reaction mixture under normal pressure or reduced pressure.

The reaction temperature is 20 to 100 ° C. and the reaction time is 1
~ 20 hours is preferred. If the reaction temperature is lower than 20 ° C, the reaction becomes slow and a long-time reaction is required. When the reaction temperature exceeds 100 ° C., many side reactions occur, which is not preferable.

The epoxy resin of the present invention can be cured alone or in combination with other epoxy resins by adding a curing agent and, if necessary, a curing accelerator as in the case of a usual epoxy resin. The curing agent that can be used in the present invention is an amine compound, an acid anhydride compound, an amide compound, a phenol compound or the like. Specific examples thereof 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, trimellitic anhydride. Acids, pyromellitic dianhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic acid anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolac, and modified products thereof, imidazo − Le, BF ₃ −
Examples include amine complexes and guanidine derivatives. 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 the epoxy group. If the amount is less than 0.7 equivalents or more than 1.2 equivalents with respect to the epoxy groups, the curing may be incomplete and good cured physical properties may not be obtained.

When the above-mentioned curing agent is used, 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. When the curing accelerator is used, the amount used is 0.1 to 5.0 parts by weight based on 100 parts by weight of the epoxy resin, if necessary. Further, if necessary, various compounding agents such as a filler such as silica, alumina, talc, a silane coupling agent, a release agent, and a pigment can be added to the epoxy resin composition of the present invention.

The epoxy resin composition of the present invention can be obtained by uniformly mixing the above components in a predetermined ratio. The cured product of the epoxy resin composition of the present invention can be easily obtained by the same method as a conventionally known method. For example, the epoxy resin of the present invention, a curing agent, and if necessary, a curing accelerator and other compounding agents are mixed as necessary with an extruder, a kneader, a roll, etc. until they are homogeneous, and then the epoxy resin is mixed. The cured product of the present invention can be obtained by obtaining a resin composition, molding the epoxy resin composition after melting using a casting or transfer molding machine, and further heating at 80 to 200 ° C.

Further, a prepreg obtained by dissolving the epoxy resin composition of the present invention in a solvent, impregnating it into a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber or paper and heating and drying it A cured product can also be obtained by hot press molding.

Specific examples of the diluting solvent used in this case are methyl ethyl ketone, acetone, methyl isobutyl ketone, etc. The amount used is usually 10 to 70% by weight in the mixture of the epoxy resin composition of the present invention and the diluent, It is preferably 15 to 65% by weight.

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

[0046]

EXAMPLES Next, the present invention will be described more specifically by way of Examples and Comparative Examples. In the following, parts are parts by weight unless otherwise specified. The conditions for measuring the glass transition temperature, the water absorption rate, and the bending strength are as follows. Glass transition temperature Thermomechanical measuring device (TMA): Vacuum Riko TM-7000 Temperature rising rate: 2 ° C / min Water absorption rate Test piece (cured product): Diameter 50 mm Thickness 3 mm Disc 100 ° C After boiling in water for 20 hours Weight increase rate (%) Bending strength According to JIS K-6911

Example 1 155 parts of the compound represented by the above formula (4), 370 parts of epichlorohydrin, and 92.5 of dimethyl sulfoxide were charged in a flask equipped with a thermometer, a cooling tube, a fractionating tube, and a stirrer while purging with nitrogen gas. Parts were charged and dissolved. 4 more
Heat to 5 degrees and add 40 parts of flaky sodium hydroxide to 10 parts.
Add it in portions over 0 minutes, then for another 2 hours at 45 ° C.
The reaction was carried out at 70 ° C for 1 hour. After completion of the reaction, using a rotary evaporator at 130 ° C. under heating and reduced pressure of 5 mHg,
Excess epichlorohydrin and dimethyl sulfoxide were distilled off, and 420 parts of methyl isobutyl ketone was added to the residue and dissolved.

Further, this methyl isobutyl ketone solution was heated to 70 ° C., 10 parts of a 30% by weight sodium hydroxide aqueous solution was added thereto, and the mixture was reacted for 1 hour, and then washed with water repeatedly to make the pH neutral. . Further, the aqueous layer is separated and removed, and methyl isobutyl ketone is distilled off from the oil layer under reduced pressure by heating using a rotary evaporator to obtain the following formula (7).

[0049]

Embedded image

(Where n is 0.08 (average value), and G
Represents a glycidyl group. ) Softening point 53.1 ℃
To obtain 196 parts of the epoxy resin (A). The epoxy equivalent of the obtained epoxy resin was 226 g / eq.

180 parts of the obtained epoxy resin (A), 18 parts of the compound represented by the formula (4), and 100 parts of methyl isobutyl ketone were charged into a flask and dissolved by stirring.
Add 0.1 parts of triphenylphosphine and stir 12
Methyl isobutyl ketone was distilled off under reduced pressure at 0 ° C.
The reaction was carried out at 0 ° C. for 2 hours, and in the formula (7), the value of n was 0.45 (average value), the epoxy equivalent was 294 g /
198 parts of an epoxy resin (B) having an eq and a softening point of 77.1 ° C. were obtained.

After 170 parts of the obtained epoxy resin (B) was dissolved in 240 parts of epichlorohydrin with stirring, 1 part of tetramethylammonium chloride was added at 40 ° C. with stirring. After that, 5.2 parts of flaky sodium hydroxide was added, and the reaction was further performed for 3 hours. After the reaction, water 120
Part was added and washed with water. After separation of oil and water, unreacted epichlorohydrin was distilled and recovered from the oil layer under reduced pressure, and 3
40 parts of methyl isobutyl ketone was added and dissolved.

Furthermore, this methyl isobutyl ketone solution was heated to 70 ° C. and a 30% by weight aqueous sodium hydroxide solution 2 was added.
After adding 1 part and reacting for 1 hour, washing with water was repeated to make the pH of the washing water neutral. Further, the water layer is separated and removed, and methyl isobutyl ketone is distilled off from the oil layer under reduced pressure by heating using a rotary evaporator to obtain the following formula (8).

[0054]

[Chemical 9]

169 parts of the epoxy resin (C) of the present invention represented by the formula (wherein X represents a hydrogen atom or a glycidyl group and G represents a glycidyl group) were obtained. The obtained epoxy resin (C) had a value of n of 0.45 in the formula (8), an epoxy equivalent of 265 g / eq and a softening point of 73.4 ° C. The glycidylation rate of the obtained epoxy resin is
It was 60% as calculated from the epoxy equivalent.

Example 2 The reaction is carried out in the same manner as in the step of obtaining the epoxy resin (C) of Example 1 except that the amount of sodium hydroxide added is changed to 6.9 parts, and the reaction is represented by the above formula (8). 171 parts of the epoxy resin (D) of the present invention was obtained. Obtained epoxy resin (D)
In the formula (8), the value of n was 0.45, the epoxy equivalent was 258 g / eq, and the softening point was 70.6 ° C. The glycidylation ratio of the obtained epoxy resin was 80% when calculated from the epoxy equivalent.

Examples 3 to 4 Epoxy resins (C), (D), phenol novolac as a curing agent (hydroxyl equivalent 106 g / eq, softening point 83)
C.) and the composition shown in the column of "Composition of compound" in Table 1 and kneaded with a roll for 15 minutes at 70.degree.
Transfer molding was performed for 180 seconds, followed by curing at 160 ° C. for 2 hours and then at 180 ° C. for 8 hours to prepare test pieces, and the glass transition temperature, water absorption rate and bending strength were measured. The results are shown in Table 1. In the table, the numerical value in the column of “composition of compound” represents part.

[0058]

[Table 1]

As is clear from Table 1, the cured product obtained by using the epoxy resin of the present invention has a high glass transition temperature, a low water absorption rate, a high bending strength, and high heat resistance, water resistance and mechanical strength. It has the characteristics of being excellent.

[0060]

INDUSTRIAL APPLICABILITY The epoxy resin of the present invention can give a cured product excellent in heat resistance, water resistance and mechanical strength, and can be used in a wide range of molding materials, casting materials, laminating materials, paints, adhesives, resists and the like. It is extremely useful for applications.

Claims (3)

[Claims] 1. A formula (1): (In the formula, n represents an average value and represents a positive number. R represents a halogen atom, an alkyl group having 1 to 8 carbon atoms, or an aryl group, and each R may be the same or different. G represents a glycidyl group, X represents a hydrogen atom or a glycidyl group, and each X may be the same as or different from each other, but n of 5 to 95 of X exist.
% Is a glycidyl group. Y represents a residue of a cycloalkane having 5 to 8 ring members which may be ring-substituted, and when the ring is substituted, the substituent is an alkyl group or aryl group having 1 to 4 carbon atoms. ) Epoxy resin represented by. 2. An epoxy resin composition containing the epoxy resin according to claim 1, a curing agent, and optionally a curing accelerator. 3. A cured product obtained by curing the epoxy resin composition according to claim 2.