JP2000143769A - Liquid epoxy resin, production of liquid epoxy resin, epoxy resin composition and its cured material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject liquid resin capable of providing a solidified material having excellent heat resistance and water resistance, containing a small amount of hydrolyzable chlorine, having low viscosity, useful as an electric/electronic part by specifying the amount of hydrolyzable chlorine. SOLUTION: This resin comprises a compound of formula I having <=2,000 ppm hydrolyzable chlorine amount when refluxed in 1N solution of sodium hydroxide in ethanol for 30 minutes and titrated with 0.01N aqueous solution of silver nitrate. The resin is obtained by a method including a process for reacting a compound of formula II with an excessive epihalohydrin in the presence of a quaternary ammonium salt (e.g. tetramethylammonium chloride, etc.), and a solid alkali metal hydroxide (e.g. sodium hydroxide, etc.), at 20-70 deg.C with stirring, for example, for about 3-25 hours.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid epoxy resin which provides a cured product having excellent heat resistance and water resistance, has a low viscosity and a small amount of hydrolyzable chlorine, a process for producing the same, and an epoxy resin composition containing the epoxy resin. And a cured product thereof.

[0002]

2. Description of the Related Art Epoxy resins can be cured with various curing agents to give cured products having generally excellent mechanical properties, water resistance, chemical resistance, heat resistance, and electrical properties. It is used in a wide range of fields, such as laminates, molding materials, and casting materials. Conventionally, in a liquid epoxy resin composition, a liquid bisphenol A type epoxy resin is most generally used as an epoxy resin. In fields where low viscosity is required, liquid epoxy resins obtained by diglycidyl etherification of hydrogenated bisphenol A are widely known. Hydrogenated bisphenol A type epoxy resin has extremely low reactivity of raw material hydrogenated bisphenol A with epihalohydrin and very low solvent solubility. For example, epihalohydrin using a Lewis acid catalyst such as boron trifluoride complex is used. Is added to the alcoholic hydroxyl group, then an alkali metal hydroxide is added,
Conventionally, a method of producing by a dehydrochlorination reaction has been employed.

[0003]

However, the above-mentioned production method involves a danger since a catalyst having a strong oxidizing power such as a boron trifluoride complex is used, and the obtained epoxy resin has a low hydrolyzable chlorine content. Is very high, 2 to 5% by the above method, so that its use in the field of electric and electronic parts that require high reliability has to be extremely limited.

[0004]

Means for Solving the Problems In view of such circumstances, the present inventors have intensively studied for a liquid epoxy resin having a low amount of hydrolyzable chlorine and a low viscosity, and as a result, have completed the present invention.

That is, the present invention provides the following equation (1).

[0006]

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A compound represented by the following formula:
The amount of hydrolyzable chlorine when titrated with an N silver nitrate aqueous solution is 2
Epoxy resin not more than 000 ppm,

(2) Equation (2)

[0009]

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And a compound represented by the formula
A method for producing an epoxy resin comprising a step of stirring and reacting at 20 to 70 ° C. in the presence of a quaternary ammonium salt and a solid alkali metal hydroxide,

(3) (a) The above (1) or (2)
Epoxy resin obtained by the production method described above, (b) an epoxy resin composition containing a curing agent,
(3) An epoxy resin composition according to the above (2) containing a curing accelerator, and (4) a cured product obtained by curing the epoxy resin composition according to the above (2) or (3). .

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin of the present invention is obtained by reacting a compound represented by the formula (2) with epihalohydrin in the presence of a solid alkali metal hydroxide and a quaternary ammonium salt. Can be.

In the method for producing an epoxy resin of the present invention, the solid alkali metal hydroxide may be sodium hydroxide or potassium hydroxide, but sodium hydroxide is particularly preferred. Examples of the shape include a flake shape and a marble shape, but a flake shape is preferable. The amount of the alkali metal hydroxide to be used is generally 1 to 5 mol, preferably 1.5 to 4 mol, per 1 equivalent of the alcoholic hydroxyl group of the compound represented by the formula (2).

The quaternary ammonium salt used as a catalyst includes tetramethylammonium chloride,
Examples thereof include tetramethylammonium bromide, trimethylbenzylammonium chloride, and triethylbenzylammonium chloride. The amount of the quaternary ammonium salt to be used is generally 0.1 to 5% by weight, preferably 0.2 to 3% by weight, based on the amount of the compound represented by the formula (2).

The amount of epihalohydrin used is usually 1 to 20 mol per 1 equivalent of the hydroxyl group of the compound represented by the formula (2),
Preferably it is 2 to 10 mol.

The reaction is carried out by simultaneously charging these components into a reactor and stirring for a certain period of time. The individual solid components are not dissolved at first and are in an inhomogeneous state, but a part of them is gradually dissolved and the reaction proceeds. The reaction time is preferably 3 to 25 hours, more preferably 5 to 20 hours. The reaction temperature is between 20 and
The temperature is 70C, but preferably 25-65C.

After completion of the reaction, the salt formed, the reaction catalyst, etc. are removed from the reaction solution by filtration and / or water washing, and epihalohydrin and the like are removed under heating and reduced pressure at 100 to 150 ° C. and a pressure of 10 mmHg or less. A resin can be obtained. The thus obtained hydrolyzable chlorine of the epoxy resin of the present invention is usually 2000 ppm or less, and that obtained under preferable conditions is 1800 ppm or less. still,
The hydrolyzable chlorine is usually obtained by dissolving a resin in a solvent, adding a predetermined amount of a predetermined solution obtained by dissolving an alkali (KOH or NaOH) in an alcohol or the like, and reacting at a predetermined temperature for a predetermined time to remove chlorine. Decomposition (extraction) is measured by potentiometric titration with a silver nitrate solution having a predetermined normality. The amount of hydrolyzable chlorine measured by this method varies depending on the temperature and time at which chlorine is decomposed. For example, EOCN-1027
(Product name, o-cresol novolak type epoxy resin,
Taking Nippon Kayaku Co., Ltd.) as an example, the difference in the amount of hydrolyzability according to the measurement method is shown in the table below.

[0018]

Table 1 (1) (2) Resin dissolving solvent Methyl ethyl ketone Dioxane Titration solution 3N NaOH-1N KOH-Ethylene glycol methanol Monobutyl ether Decomposition temperature Room temperature Reflux Decomposition time 2 hours 30 minutes Hydrolytic chlorine content Max. (3) (4) Resin dissolving solvent dioxane dioxane titration solution 1N KOH-1N KOH-ethanol ethanol Epoxy Resin Handbook "(Nikkan Kogyo Shimbun)

As described above, in the method (1) in which the decomposition conditions are mild (ISO method), the amount of hydrolyzable chlorine tends to be smaller by one order than in the other methods. A similar phenomenon is known as shown in FIG.

[0020]

[Table 2] Analysis conditions (1) (2) (3) (4) Epoxy resin EOCN-1020 max. 10 150-200 330-400 550-700 EOCN-1025 max. 10 max. 100 180-250 340-410 EOCN-102S Maximum 30 250-400 700-800 1000-1200 Note) In the table, all epoxy resins are o-cresol novolak type epoxy resin, manufactured by Nippon Kayaku Co., Ltd. The numerical values represent the amount of hydrolyzable chlorine (ppm). (Epoxy Resin Handbook, edited by Masaki Shinbo (Nikkan Kogyo Shimbun))

As described above, the amount of hydrolyzable chlorine varies depending on the measurement conditions, but the amount of hydrolyzable chlorine in the epoxy resin of the present invention is determined by refluxing the resin dissolved in a solvent in a 1N potassium hydroxide ethanol solution for 30 minutes. It refers to the amount of hydrolyzable chlorine measured by the method of (3) when titrated with a 0.01 N silver nitrate aqueous solution.

In order to further reduce the amount of hydrolyzable chlorine to an epoxy resin, the recovered epoxy resin is dissolved again in a solvent such as toluene, methyl isobutyl ketone, methyl ethyl ketone and the like. 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 0.1 to 1 equivalent of the hydroxyl group of the phenol resin used for the epoxidation.
The amount is from 0.01 to 0.3 mol, particularly preferably from 0.05 to 0.2 mol. The reaction temperature is 50 to 120 ° C, and the reaction time is usually 0.5 to 2 hours. After the completion of the reaction, the formed salts and the like are removed by filtration or washing with water, etc., and the epoxy resin of the present invention having a small amount of hydrolyzable chlorine is obtained by distilling off solvents such as toluene, methyl isobutyl ketone and methyl ethyl ketone under reduced pressure under heating. can get. The amount of hydrolyzable chlorine in the epoxy resin thus purified is usually 1800 p.
pm or less, obtained under preferable conditions is 1500p
pm or less.

Hereinafter, the epoxy resin composition of the present invention will be described. In the epoxy resin compositions described in the above (2) and (3), the epoxy resin of the present invention can be used alone or in combination with another epoxy resin. When used in combination, the proportion of the epoxy resin of the present invention in the total epoxy resin is preferably at least 10% by weight, particularly preferably at least 20% by weight. Other epoxy resins that can be used in combination with the epoxy resin of the present invention include novolak type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, biphenyl type epoxy resin and the like, but these may be used alone. Two or more kinds may be used in combination.

As the curing agent used in the epoxy resin composition of the present invention, 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 diaminodiphenylmethane, diethylenetriamine, triethylenetetramine, diaminodiphenylsulfone, isophoronediamine, dicyandiamide, a polyamide resin synthesized from a dimer of linolenic acid and ethylenediamine, phthalic anhydride, and trianhydride. Melitic 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 complex, guanidine derivative and the like. It is not limited to these. These may be used alone or in combination of two or more.

The amount of the curing agent used in the epoxy resin composition of the present invention is preferably 0.7 to 1.2 equivalents per equivalent of the epoxy group of the epoxy resin. If the amount is less than 0.7 equivalents or more than 1.2 equivalents with respect to 1 equivalent of epoxy group, curing may be incomplete and good cured physical properties may not be obtained.

When the above curing agent is used, a curing accelerator may be used in combination. Specific examples of the curing accelerator that can be used include, for example, 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 is used in an amount of 0.1 to 5.0 parts by weight based on 100 parts by weight of the epoxy resin as required.

The epoxy resin of the present invention optionally contains an inorganic filler. Specific examples of the inorganic filler that can be used include silica, alumina, and talc. The inorganic filler is used in an amount occupying 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, and calcium stearate, and a pigment can be added.

The epoxy resin composition of the present invention can be obtained by uniformly mixing the components. 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 of the present invention is thoroughly mixed with the epoxy resin of the present invention, a curing agent, if necessary, a curing accelerator, an inorganic filler, and the like, using an extruder, a kneader, a roll, or the like, as necessary, until the epoxy resin becomes uniform. A composition is obtained, and the epoxy resin composition is melted and then molded using a casting or transfer molding machine.
For 2 to 10 hours to obtain the cured product of the present invention.

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, etc., and is used to prepare glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, paper, etc. A prepreg obtained by impregnating a substrate and drying by heating may be subjected to hot press molding to obtain a cured product. The solvent in this case is usually 10 to 70% by weight, preferably 1% by weight in the mixture of the epoxy resin composition of the present invention and the solvent.
An amount occupying 5 to 70% by weight, preferably 15 to 65% by weight, is used.

[0030]

EXAMPLES The present invention will be described below in more detail with reference to Examples and Comparative Examples. In the following, parts are by weight unless otherwise specified.

Example 1 A nitrogen gas purge was applied to a flask equipped with a thermometer, a dropping funnel, a cooling tube, and a stirrer, while 120 parts of the crystalline compound represented by the above formula (2), 80 parts of flaky sodium hydroxide, 1.2 parts of triethylbenzylammonium chloride and 370 parts of epichlorohydrin were simultaneously charged and heated to 40 ° C, and thereafter, stirring was continued at 40 ° C for 15 hours. After completion of the reaction, the resultant was filtered to remove generated salts and the like, and washed once with water to remove quaternary ammonium salts and the like. Using a rotary evaporator, excess epichlorohydrin and the like were distilled off under heating and reduced pressure at 130 ° C., and 352 parts of methyl isobutyl ketone were added to the residue and dissolved.

Further, the solution of methyl isobutyl ketone was heated to 70 ° C., and a 30% by weight aqueous sodium hydroxide solution 1 was added.
After adding 0 parts and reacting for 1 hour, washing with water was repeated until the pH of the washing solution of the reaction mixture became neutral. 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 to obtain the epoxy resin (A) 127 of the present invention represented by the above formula (1).
Got a part. The obtained epoxy resin is a yellow liquid and has 2
The viscosity at 5 ° C. is 1470 cps, and the epoxy equivalent is 218.
g / eq. The amount of hydrolyzable chlorine was measured by dissolving the obtained epoxy resin in dioxane, hydrolyzing with a 1N potassium hydroxide / ethanol solution under reflux for 30 minutes, and then titrating with a 0.01N silver nitrate aqueous solution. As a result, it was 630 ppm.

Example 2 A reaction was carried out in the same manner as in Example 1 except that the amount of the flaky sodium hydroxide was changed to 120 parts to obtain 152 parts of the epoxy resin (B) of the present invention represented by the above formula (1). Was. The obtained epoxy resin is a yellow liquid and has a viscosity of 87 at 25 ° C.
0 cps and the epoxy equivalent was 201 g / eq. The amount of hydrolyzable chlorine was measured in the same manner as in Example 1 and found to be 710 ppm.

Comparative Example 1 As a comparative example, the resin properties of a commercially available hydrogenated bisphenol A type epoxy resin (trade name: EP-4080, manufactured by Asahi Denka, epoxy resin (C)) were measured in the same manner. The viscosity at 25 ° C. of the epoxy resin (C) was 2100 cps, the epoxy equivalent was 237 g / eq, and the value of the amount of hydrolyzable chlorine measured in the same manner as in Example 1 was 39000 ppm.

[0035]

The epoxy resin of the present invention has an extremely high purity as compared with the conventionally used hydrogenated bisphenol A type epoxy resin, so that a cured product having excellent reliability can be obtained. It is extremely useful in a wide range of applications such as materials, casting materials, laminate materials, paints, adhesives, resists, and the like.

Claims (5)

[Claims] (1) Formula (1) Wherein the amount of hydrolyzable chlorine is 2,000 ppm when refluxed in a 1N potassium hydroxide ethanol solution for 30 minutes and titrated with a 0.01 N silver nitrate aqueous solution.
An epoxy resin that is: (2) Formula (2) A method for producing an epoxy resin comprising a step of reacting the compound represented by the formula (1) with an excess epihalohydrin in the presence of a quaternary ammonium salt and a solid alkali metal hydroxide at 20 to 70 ° C with stirring. 3. An epoxy resin composition comprising (a) an epoxy resin obtained by the method according to claim 1 or (b) and (b) a curing agent. 4. The epoxy resin composition according to claim 3, further comprising a curing accelerator. 5. A cured product obtained by curing the epoxy resin composition according to claim 2 or 3.