JPH08319335A - Epoxy resin, epoxy resin composition and cured product thereof - Google Patents

Abstract

PURPOSE: To obtain an epoxy resin having specific structure, capable of giving cured products with high resistance to heat and water, and also useful in a wide range of applications such as molding materials, laminating materials, coating materials, adhesives, etc., because of its low viscosity. CONSTITUTION: This epoxy resin has a structure of formula I (R is H or a 1-4C alkyl; G is glycidyl) and is obtained, for example, by adding an alkali metal hydroxide such as sodium hydroxide to a dissolved mixture of a compound of formula II such as monomethylolated phenol and an excess of an epihalohydrin followed by reaction at 20-120 deg.C for 1-20h. It is preferable that the amounts of the epihalohydrin and alkali metal hydroxide to be used be 1.5-10mol and 0.9-1.1mol per equivalent of the hydroxyl group of the compound of formula II, respectively. And, for the reaction to proceed smoothly, the reaction is recommended to carry out in the presence of e.g. an alcohol. When a curing agent is to be incorporated in this resin, it is preferable that the amount of the curing agent to be used be 0.7-1.2 equivalent based on the epoxy group of the resin.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an epoxy resin and an epoxy resin composition which give a cured product having a low viscosity and excellent heat resistance and water resistance.

[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 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. In particular, liquid bisphenol A type epoxy resins are used in a wide range of fields because of their workability that they have fluidity at room temperature. On the other hand, low-viscosity epoxy resins include polyfunctional alcohol epoxy resins such as hydrogenated bisphenol A type epoxy resins and 1,6-hexanediol epoxy resins, which are used as reactive diluents.

[0003]

With the remarkable progress of the electric and electronic fields in recent years, the demands on the electrically insulating materials used for these have become strict, and the epoxy resin having a low viscosity and excellent cured physical properties has been obtained. Is expected. As a low-viscosity epoxy resin, there is a polyfunctional alcohol epoxy resin, but a cured product thereof has extremely poor heat resistance and high water absorption. Further, although the liquid bisphenol A type epoxy resin has excellent cured physical properties, it cannot be said to be sufficient in terms of workability because of its high viscosity.

[0004]

In view of these circumstances, the inventors of the present invention have earnestly studied for a liquid epoxy resin having a low viscosity and excellent heat resistance and water resistance, and as a result, the epoxy resin having a specific structure has been described above. The inventors have found that the above characteristics are satisfied and completed the present invention.

That is, the present invention provides (1) the following formula (1)

[0006]

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(In the formula, each R independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. G represents a glycidyl group.)

An epoxy resin represented by

(2) An epoxy resin composition containing the epoxy resin according to (1) above and a curing agent, (3) an epoxy resin composition according to (2) above containing a curing accelerator,
(4) The epoxy resin composition according to the above (2) or (3) containing an inorganic filler, (5) the epoxy resin composition according to the above (2), (3) or (4) cured. It provides a cured product.

The present invention will be described in detail below. The epoxy resin represented by the formula (1) is, for example, the formula (2)

[0011]

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(In the formula, R has the same meaning as in formula (1).)

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

Specific examples of the compound represented by the formula (2) include monomethylolated phenol, monomethylolated cresol, monomethylolated xylenol, monomethylolated trimethylphenol, monomethylolated propylphenol, monomethylolated butylphenol, Examples include, but are not limited to, monomethylolated methylbutylphenol and o-, m-, p-isomers thereof and the like.

As a method for obtaining the epoxy resin represented by the formula (1), a known method can be adopted. For example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added all at once to a dissolved mixture of the compound represented by the formula (2) and an excess of epihalohydrin, or 20 to 1 while being added.
It can be obtained by reacting at a temperature of 20 ° C. for 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 to a dissolved mixture of the compound represented by the formula (2) and epihalohydrin as a catalyst 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 the formula (2) obtained by the reaction in step (1) and reacted at a temperature of 20 to 120 ° C. for 1 to 20 hours to dehydrohalogenate (ring closure ) May be used.

The amount of epihalohydrin used in these reactions is usually 1 to 20 mol, preferably 1.5 to 1 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 0.8 to 1 equivalent of the hydroxyl group of the compound represented by the formula (2).
It is 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.

These epoxidation reaction products are dissolved in an organic solvent after removing epihalohydrin and other solvents after heating with or without water washing under reduced pressure. Specific examples of the organic solvent that can be used usually include methyl isobutyl ketone, benzene, toluene, xylene and the like, but methyl isobutyl ketone and toluene are preferable.
Moreover, these can be used individually or in mixture.

Then, 0.01 to 0.3 times equivalent of alkali metal hydroxide is added to 1 equivalent of hydroxyl group of the compound of the formula (2), and stirred at 50 to 80 ° C. for 30 minutes to 3 hours to remove the compound. It is preferable to carry out a hydrogen halide reaction. At this time, the alkali metal hydroxide is preferably used as an aqueous solution of 10 to 40% by weight.

After completion of the reaction, the resin solution was washed with water several times,
The desired epoxy resin can be obtained by distilling off the organic solvent under heating and reduced pressure.

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 and the like as in the case of a usual epoxy resin. The epoxy resin composition of the present invention contains the epoxy resin of the present invention, a curing agent, and optionally a curing accelerator and an inorganic filler. The curing agent used in the epoxy resin composition of the present invention is an amine compound, an acid anhydride compound, an amide compound, a phenol compound or the like. 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, and anhydride. Trimellitic acid, pyromellitic dianhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic acid anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, phenol novolac, and modified products thereof. , Imidazole, BF ₃ -amine complex, guanidine derivative and the like. 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 groups of the epoxy resin.
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 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 imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2- (dimethylaminomethyl) phenol, and 1,8-diaza. -Tertiary amines such as bicyclo (5,4,0) undecene-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.

The epoxy resin composition of the present invention optionally contains an inorganic filler. Specific examples of the inorganic filler that can be used include silica, alumina, talc and the like.
The inorganic filler is used in an amount of 0 to 90% by weight in the epoxy resin composition of the present invention. Further, to the epoxy resin composition of the present invention, various compounding agents such as a silane coupling agent, a release agent such as stearic acid, palmitic acid, zinc stearate, calcium stearate, and a pigment may be added, if necessary. it can.

The epoxy resin composition of the present invention can be obtained by uniformly mixing the above-mentioned 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, an inorganic filler and other compounding agents are used until necessary, using an extruder, a kneader, a roll, etc. To obtain an epoxy resin composition, and the epoxy resin composition is melted and then molded using a casting or transfer molding machine, and further at 80 to 200 ° C.
The cured product of the present invention can be obtained by heating to.

The prepreg obtained by dissolving the 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, paper, etc. and drying it by heating A cured product can be obtained by press molding.

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

[0029]

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 measurement conditions of heat distortion temperature and water absorption are as follows. Heat distortion temperature According to JIS-K6911 Water absorption Test piece (cured product): Diameter 50 mm Thickness 3 mm Disc Weight increase rate (%) after boiling in 100 ° C. water for 20 hours

Example 1 The following formula (3) was applied to a flask equipped with a thermometer, a cooling tube, a fractionating tube, and a stirrer while purging with nitrogen gas.

[0031]

[Chemical 4]

124 parts of the compound represented by: 740 parts of epichlorohydrin and 370 parts of dimethyl sulfoxide were charged and dissolved. Further, the mixture was heated to 45 ° C., 80 parts of flaky sodium hydroxide was added portionwise over 100 minutes, and then,
Further, the reaction was carried out at 45 ° C. for 2 hours and at 70 ° C. for 1 hour. After the reaction is completed, use a rotary evaporator at 130 ° C for 5m
Excessive epichlorohydrin and dimethyl sulfoxide were distilled off under heating and reduced pressure of Hg, and 470 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 wt% sodium hydroxide aqueous solution was added, and the reaction was carried out for 1 hour. Then, washing with water was repeated to make the washing solution 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 (4).

[0034]

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217 parts of the epoxy resin (A) of the present invention represented by (in the formula (4), G represents a glycidyl group) was obtained. The obtained epoxy resin was liquid (viscosity at 25 ° C .: 400 centipoise) and had an epoxy equivalent of 1
It was 38 g / eq.

Example 2 The compound represented by the above formula (3) was replaced by the following formula (5)

[0037]

[Chemical 6]

Reaction was carried out in the same manner as in Example 1 except that 152 parts of the compound represented by

[0039]

[Chemical 7]

245 parts of the epoxy resin (B) of the present invention represented by (in the formula (6), G represents a glycidyl group) were obtained. The obtained epoxy resin was liquid (viscosity at 25 ° C .: 1300 centipoise), and the epoxy equivalent was 151 g / eq.

Examples 3, 4 Epoxy resins (A), (B)
Epoxy resin of 6-hexanediol (epoxy resin (C), epoxy equivalent 154 g / eq), Kayahard MCD (manufactured by Nippon Kayaku Co., Ltd., methylendomethylenetetrahydrophthalic anhydride) as a curing agent, 2 as a curing accelerator -Ethyl-4-methylimidazole (2E4MZ)
Was blended with the composition shown in the column of the composition of the blend in Table 1, and these were cured at 80 ° C. for 2 hours, then at 120 ° C. for 2 hours, and further at 200 ° C. for 5 hours to prepare a test piece, The heat distortion temperature and water absorption were measured. The results are shown in Table 1. In the table, the numerical values in the column of composition of formulation represent parts.

[0042]

[Table 1] Table 1 Example 1 Example 2 Comparative Example 1 Composition of compound Epoxy resin (A) 100 Epoxy resin (B) 100 Epoxy resin (C) 100 Kayahard MCD 116 106 104 Physical properties of cured product Heat deformation temperature ( ℃) 123 127 45 Water absorption rate (%) 2.3 2.1 4.9

As is clear from Table 1, the cured product obtained by using the epoxy resin of the present invention has a high heat distortion temperature,
Since it has a low water absorption, it also has the characteristics of excellent heat resistance and water resistance.

[0044]

The epoxy resin of the present invention can give a cured product excellent in heat resistance and water resistance, and has a low viscosity, so that it is a molding material, a casting material, a laminating material, a paint, an adhesive, a resist, etc. It is extremely useful for a wide range of applications.

Claims (5)

[Claims] 1. The following formula (1): (In the formula, each R independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and G represents a glycidyl group.). 2. An epoxy resin composition containing the epoxy resin according to claim 1 and a curing agent. 3. The epoxy resin composition according to claim 2, which contains a curing accelerator. 4. The epoxy resin composition according to claim 2, which contains an inorganic filler. 5. A cured product obtained by curing the epoxy resin composition according to claim 2, 3 or 4.