JP3540018B2 - Epoxy resin composition and cured product thereof - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an epoxy resin composition that gives a cured product having excellent heat resistance and water resistance, and a cured product thereof.
[0002]
[Prior art]
Epoxy resins can be cured with various curing agents to give cured products with excellent mechanical properties, water resistance, chemical resistance, heat resistance, and electrical properties. It is used in a wide range of fields such as materials and casting materials. Conventionally, there is a liquid and solid bisphenol A type epoxy resin obtained by reacting epichlorohydrin with bisphenol A as the epoxy resin most used industrially. Other flame-retardant bromine-containing epoxy resins obtained by reacting tetrabromobisphenol A with a liquid bisphenol A-type epoxy resin are used industrially as general-purpose epoxy resins.
[0003]
[Problems to be solved by the invention]
However, the general-purpose epoxy resin as described above has a disadvantage that as the molecular weight increases, the heat resistance of a cured product obtained by using the resin decreases. Further, when a polyfunctional epoxy resin such as orthocresol novolak epoxy resin is added to a general-purpose epoxy resin, the heat resistance of the cured product is improved, but the water resistance is reduced.
[0004]
[Means for Solving the Problems]
In view of these circumstances, the present inventors have conducted intensive studies in search of an epoxy resin composition that gives a cured product having excellent heat resistance and water resistance. As a result, an epoxy resin composition containing the following specific epoxy resin was obtained by curing the cured product. The present invention has been found to impart excellent heat resistance and water resistance to the present invention.
[0005]
That is, the present invention provides (1) (a) Formula (1)
[0006]
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[0007]
(In the formula, n is an average value and 0 <n ≦ 10. Each R independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, or an aryl group. X represents an optionally substituted cycloalkane residue having 5 to 8 ring members, and when substituted, the substituent is an alkyl having 1 to 4 carbon atoms. An epoxy resin mixture represented by the formula:
(B) a curing agent,
And (c) an epoxy resin composition containing a curing accelerator if necessary; and (2) a cured product obtained by curing the epoxy resin composition according to (1).
[0008]
Hereinafter, the present invention will be described in detail.
[0009]
The epoxy resin mixture represented by the formula (1), which is one of the components of the epoxy resin composition of the present invention, is, for example, a compound represented by the formula (2)
[0010]
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[0011]
(Wherein X and R represent the same meaning as in formula (1))
By reacting the compound represented by with epihalohydrin in the presence of an alkali metal hydroxide.
[0012]
Specific examples of the compound represented by the formula (2) include, for example, the following formula (3)
[0013]
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[0014]
Or the following equation (4)
[0015]
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[0016]
Or the following equation (5)
[0017]
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[0018]
However, the present invention is not limited thereto.
[0019]
As a method for obtaining an epoxy resin mixture which is one of the components of the present invention from the compound represented by the formula (2), a known method can be employed. 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 (2) and an excess of epihalohydrin such as epichlorohydrin or epibromhydrin, or 20- A method in which the reaction is carried out at a temperature of 120 ° C. is exemplified. Hereinafter, unless otherwise specified, the epoxy resin mixture obtained by the above reaction is referred to as epoxy resin (I).
[0020]
In the reaction for obtaining the epoxy resin (I), an aqueous solution of the alkali metal hydroxide may be used. In this case, the aqueous solution of the alkali metal hydroxide is continuously added to the reaction system, and under reduced pressure. Alternatively, a method may be employed in which water and epihalohydrin are continuously discharged under normal pressure, liquids are separated, water is removed, and epihalohydrin is continuously returned to the reaction system.
[0021]
In addition, a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide, trimethylbenzylammonium chloride or the like is added as a catalyst to a dissolved mixture of the compound represented by the formula (2) and epihalohydrin at 50 to 150 ° C. A method in which a solid or aqueous solution of an alkali metal hydroxide is added to a halohydrin etherified product obtained by reacting for 5 to 5 hours, and the reaction is performed again at a temperature of 20 to 120 ° C. for 1 to 10 hours to perform dehydrohalogenation (ring closing). May be.
[0022]
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 to be used is 0.8 to 15 mol, preferably 0.9 to 11 mol, per 1 equivalent of the hydroxyl group of the compound represented by the formula (2). Further, in order to make the reaction proceed smoothly, it is preferable to perform the reaction by adding an aprotic polar solvent such as dimethyl sulfone and dimethyl sulfoxide, in addition to alcohols such as methanol and ethanol, and dimethyl sulfoxide is particularly preferable. .
[0023]
When alcohols are used, the amount used is 2 to 20% by weight, more preferably 4 to 15% by weight, based on the amount of epihalohydrin. When an aprotic polar solvent is used, it is 5 to 100% by weight, more preferably 10 to 90% by weight, based on the amount of epihalohydrin.
[0024]
After the reaction product obtained by these epoxidation reactions is washed with or without water, epihalohydrin and other additional solvents are removed at 150 to 250 ° C. and a pressure of 10 mmHg or less under heating and reduced pressure. In order to further reduce the amount of the hydrolyzable halogenated epoxy resin (I), the recovered epoxy resin (I) is dissolved again in a solvent such as toluene or methyl isobutyl ketone, and the alkali metal such as sodium hydroxide or potassium hydroxide is used. An aqueous solution of a hydroxide may be added for further reaction to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is preferably 0.01 to 0.3 mol, particularly preferably 0.05 to 0.3 mol per equivalent of the hydroxyl group of the compound represented by the formula (2) used for the epoxidation. 0.2 mol. The reaction temperature is 50 to 120 ° C, and the reaction time is usually 0.5 to 2 hours.
[0025]
After completion of the reaction, the formed salt is removed by filtration, washing with water, or the like, and the solvent such as toluene and methyl isobutyl ketone is distilled off under reduced pressure under heating to obtain the epoxy resin (I).
[0026]
In addition, the epoxy resin (I) having a higher molecular weight component can be prepared by a known method, for example, by combining the epoxy resin obtained by the above method and the compound represented by the formula (2) in the presence of a basic catalyst. , In a molten state or in a solvent at a temperature between 70 and 200 ° C for 0.5 to 20 hours.
[0027]
In this case, the charge ratio of each component is preferably from 0 to 0.9 equivalent, particularly preferably from 0 to 0. 0 equivalent of the compound represented by the formula (2) to 1 equivalent of the epoxy resin (I) obtained by the above method. 85 equivalents are preferred.
[0028]
Further, examples of the basic catalyst include triphenylphosphine, sodium hydroxide, quaternary ammonium salts, imidazoles, and the like, and the amount of the basic catalyst is 0.001 to 1.0% by weight based on the epoxy resin (I). Is preferable, and particularly preferably 0.005 to 0.5% by weight. When a solvent is used, methyl isobutyl ketone, toluene and the like can be used.
[0029]
In the epoxy resin composition of the present invention, an epoxy resin other than the epoxy resin (I) can be used in combination.
[0030]
As the curing agent of the component (b) in the above (1), various ones can be used and are not particularly limited. For example, amine compounds, acid anhydride compounds, amide compounds, phenol compounds and the like can be used. Specific examples of the curing agent that can be used include a polyamide resin synthesized from diamine of diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, and linolenic acid, and ethylenediamine, phthalic anhydride, and trianhydride. Mellitic acid, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolak, and modified products thereof, imidazole , BF ₃ -amine complexes, guanidine derivatives and the like. Further, the compound represented by the formula (2) used as a raw material of the epoxy resin (I) can also be used as a curing agent. These curing agents may be used alone or in combination of two or more.
[0031]
The amount of these curing agents used is preferably 0.7 to 1.2 equivalents to 1 equivalent of the epoxy group of the epoxy resin (I) and the other epoxy resin used if necessary. If the amount is less than 0.7 equivalents or more than 1.2 equivalents with respect to 1 equivalent of the epoxy group, curing may be incomplete and good cured physical properties may not be obtained.
[0032]
When using the above curing agent, a curing accelerator may be used in combination. As a curing accelerator, for example, imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2- (dimethylaminomethyl) phenol, 1,8-diaza-bicyclo (5,4,0) Examples include tertiary amines such as undecene-7, phosphines such as triphenylphosphine, and salts of organometallic compounds such as tin octylate. These may be used alone or in combination of two or more. The curing accelerator is preferably used in an amount of 0.01 to 15 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the epoxy resin (I) and the other epoxy resin used in combination as necessary. Is preferred.
[0033]
The epoxy resin composition of the present invention may further contain known additives, if necessary. Examples of additives that can be used include inorganic fillers such as silica, alumina, talc, and glass fibers, silane coupling agents, release agents, and pigments.
[0034]
The epoxy resin composition of the present invention is obtained by uniformly mixing the components at the above-described ratio. The epoxy resin composition of the present invention can be easily made into a cured product by a method similar to a conventionally known method. For example, the epoxy resin (I) and a curing agent, and if necessary, a curing accelerator and other additives are sufficiently mixed, if necessary, using an extruder, a kneader, a roll, or the like to obtain an epoxy resin composition. The epoxy resin composition is melted, molded using a casting or transfer molding machine, and further heated at 80 to 200 ° C. for 2 to 10 hours to obtain a cured product.
[0035]
Further, the epoxy resin composition of the present invention is dissolved in a diluting solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, etc., and impregnated into a base material such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber and paper. The prepreg obtained by heating and drying may be subjected to hot press molding to obtain a cured product.
[0036]
The amount of the diluting solvent used in this case is usually 10 to 70% by weight, preferably 15 to 65% by weight, based on the total weight of the epoxy resin composition of the present invention and the diluting solvent.
[0037]
The cured product thus obtained is excellent in heat resistance, water resistance and mechanical strength, and can be used in a wide range of fields requiring heat resistance, water resistance and high mechanical strength. Specifically, it is useful as any electric or electronic material such as a sealing material, a laminate, or an insulating material. Further, it can also be used in the fields of molding materials, adhesives, composite materials, paints and the like.
[0038]
【Example】
Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the following, parts are by weight unless otherwise specified.
[0039]
Production Example 1
A nitrogen gas purge was applied to a flask equipped with a thermometer, a condenser and a stirrer, and 310 parts of the compound represented by the formula (3), 720 parts of epichlorohydrin, and 185 parts of dimethyl sulfoxide were charged and dissolved. The mixture was further heated to 45 ° C., and 80.8 parts of flaky sodium hydroxide (99% pure content) was added in portions over 90 minutes. Thereafter, the mixture was further reacted at 45 ° C. for 2 hours and at 70 ° C. for 1 hour. After completion of the reaction, dimethyl sulfoxide and epichlorohydrin were distilled off under heating and reduced pressure at 130 ° C., and 844 parts of methyl isobutyl ketone was added to the residue and dissolved.
[0040]
Further, the solution of methyl isobutyl ketone was heated to 70 ° C., 20 parts of a 30% by weight aqueous sodium hydroxide solution was added, and the mixture was allowed to react for 1 hour. Further, the aqueous layer was separated and removed, and methyl isobutyl ketone was distilled off from the oil layer under reduced pressure by heating using a rotary evaporator.
[0041]
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[0042]
409 parts of an epoxy resin (A) represented by the following formula was obtained. The obtained epoxy resin had a softening point of 53.3 ° C. and an epoxy equivalent of 227 g / eq. When calculated from the epoxy equivalent, the value of n in the equation was 0.09.
[0043]
Example 1, Comparative Example 1
Epoxy resin (A) obtained in Production Example 1, bisphenol A type epoxy resin (Epicoat 828, manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 186 g / eq) as a comparison, phenol novolak (hydroxyl equivalent: 106 g / eq, manufactured by Nippon Kayaku Co., Ltd.), triphenylphosphine (TPP) was used as a curing accelerator, blended in the composition shown in Table 1, kneaded with a roll at 70 ° C. for 15 minutes, and the epoxy resin composition of the present invention. And an epoxy resin composition for comparison was obtained. Next, this was subjected to transfer molding at 150 ° C. for 180 seconds, and then cured at 160 ° C. for 2 hours and further at 180 ° C. for 8 hours to prepare a test piece, and the glass transition temperature and the water absorption were measured. Table 1 shows the results. In addition, the measurement conditions of a glass transition point and a water absorption are as follows. Also, in the table, the numerical values in the column of the composition of the composition indicate parts.
[0044]
Glass transition point thermomechanical analyzer (TMA): TM-7000 manufactured by Vacuum Riko Co., Ltd.
Heating rate: 2 ° C / min
Water absorption test piece (cured product): 50 mm in diameter
Weight increase rate (%) after boiling for 3 hours in water at 100 ° C with a thickness of 3mm disk
[0045]
[Table 1]
Production Example 2
While applying a nitrogen gas purge to a flask equipped with a thermometer, a condenser, and a stirrer, 159 parts of the epoxy resin obtained in Production Example 1, 42 parts of the compound represented by the formula (3), and 200 parts of methyl isobutyl ketone After stirring and dissolving, 0.16 parts of triphenylphosphine was added, methyl isobutyl ketone was distilled off under reduced pressure at 120 ° C. with stirring, and the reaction was further performed at 150 ° C. for 2 hours, and represented by the above formula (6). Thus, 201 parts of an epoxy resin (B) having an epoxy equivalent of 470 g / eq and a softening point of 85.2 ° C. was obtained. When calculated from the epoxy equivalent, the value of n in the formula was 1.42.
[0046]
Example 2, Comparative Example 2
Epoxy resin (B) obtained in Production Example 2, bisphenol A type epoxy resin (Epomic R-301, manufactured by Mitsui Petrochemical Co., Ltd., epoxy equivalent: 468 g / eq) as a comparison, phenol novolak (hydroxyl equivalent: 106 g) as a curing agent / Eq, manufactured by Nippon Kayaku Co., Ltd.), triphenylphosphine (TPP) was used as a curing accelerator, blended with the composition shown in Table 2, kneaded with a roll at 70 ° C. for 15 minutes, and the epoxy resin of the present invention. An epoxy resin composition for comparison with the composition was obtained. Next, this was subjected to transfer molding at 150 ° C. for 180 seconds, and then cured at 160 ° C. for 2 hours and further at 180 ° C. for 8 hours to prepare a test piece, and the glass transition temperature and the water absorption were measured under the above conditions. Table 2 shows the results. The numerical values in the column of the composition of the blend in the table indicate parts by weight.
[0047]
[Table 2]
As described above, from Tables 1 and 2, the cured product of the epoxy resin composition of the present invention showed a higher glass transition point and a lower water absorption than the cured product of the known epoxy resin composition.
[0048]
【The invention's effect】
The epoxy resin composition of the present invention provides a cured product having excellent heat resistance and water resistance as compared with conventionally used epoxy resin compositions.
[0049]
That is, the epoxy resin composition of the present invention can provide a cured product having excellent properties of heat resistance, water resistance and mechanical strength, and can be used for molding materials, casting materials, laminate materials, paints, adhesives, resists and the like. Is very useful for a wide range of applications.

Claims (2)

(A) Equation (6)
( Where n is an average and 0.09 ≦ n ≦ 1.42 ), an epoxy resin mixture represented by the following formula:
(B) phenol novolak ,
And (c) an epoxy resin composition containing, if necessary, a curing accelerator. A cured product obtained by curing the epoxy resin composition according to claim 1.