JPH11263767A - Method for producing high-purity cyanate ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a phenolic alkali metal salt as a raw material and to produce a highly pure cyanate ester in a safe and simple process with high yield without producing by-products such as dialkylcyanoamide. To provide the resulting manufacturing method. The following general formula (I): (I) (A is each independently a hydrogen atom or carbon atom 1
An alkyl group of 6 or more and X is a single bond, and having 1 to 2 carbon atoms.
A phenolate represented by an organic group, a carbonyl group, a sulfone group, a divalent sulfur atom or an oxygen atom of 0, and I is an integer of 0 to 4), an aqueous phenolate solution prepared from an alkali metal hydroxide and water A method for producing a cyanate ester, comprising simultaneously adding and reacting a cyanogen halide with water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sealing electronic parts,
The present invention relates to a method for producing a thermosetting cyanate ester useful for a laminate, a composite material, a molding material, and an adhesive.

[0002]

2. Description of the Related Art Heretofore, as a method for producing a cyanate ester, (1) a method in which a cyanogen halide is reacted with phenol in the presence of a tertiary amine, (2) an alkali metal salt of an alcohol or phenol compound and halogenation And a method by reaction with cyanide (A.
W. Snow in Chemistry and
Technology of Cyanate Est
er Resins', Chap. 2 (Ed.
I. Hamerton), Blackie Aca
demic and Professional, G
lasgow, 1994, pp. 139-143. 7-57). In the case of the method (1), since a side reaction to form a liquid dialkyl cyanoamide having low volatility occurs, it remains as an impurity in the prepolymer, and has a drawback that the impurity volatilizes during thermosetting to form a void. In the case of the method (2), since the generated cyanate reacts with phenoxide to produce imidocarbonate, the method cannot be applied to other than alcoholic or phenolic compounds having a bulky substituent at the position adjacent to the hydroxyl group. (R. Stroh et al, Angew. C
hem. , 72, 1000 (1964)). On the other hand, a method for producing a cyanate ester of a phenol having no substituent using a mixed solvent of water and an organic solvent has been reported (Japanese Patent Publication No. 56-3859). As described above, according to a recent analysis method, it has been revealed that many imide carbonates are by-produced by this method.

[0003]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to use a phenol alkali metal salt as a raw material without producing by-products such as dialkylcyanoamides, and to provide a safe and simple process. Accordingly, an object of the present invention is to provide a production method by which a high-purity cyanate ester can be obtained in a high yield.

[0004]

Means for Solving the Problems As a result of intensive studies on a method for producing a cyanate ester, the present inventors have found that aqueous solution of phenolic alkali metal hydroxide phenolate is used alone as a reaction solvent. By using an alkali metal salt as a base without using a tertiary amine and reacting the phenolate and cyanogen halide at a low concentration, the by-products of dialkylcyanoamide and imidocarbonate are suppressed, and a stable comparison is made in water. The inventors have found that a cyanate ester having high chemical purity can be produced and precipitated, and have completed the present invention. That is, the present invention is as follows. (1) The following general formula (I)

[0005]

Embedded image (I) (wherein, A is each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X is a single bond,
To 20, an organic group, a carbonyl group, a sulfone group, a divalent sulfur atom or an oxygen atom, and I represents an integer of 0 or more and 4 or less. A) a phenolate aqueous solution prepared from phenols, alkali metal hydroxides and water represented by the formula (1), and a cyanogen halide, wherein the reaction is carried out by adding the reaction to water in parallel. Method. (2) The method for producing a cyanate ester according to the above (1), wherein the phenolate of a phenol alkali metal hydroxide has a solubility of 1% or more in water. (3) The method for producing a cyanate ester according to the above (1), wherein the phenol is represented by the following formula.

[0006]

Embedded image (4) The aqueous phenolate solution of an alkali metal hydroxide of phenols converts phenols into hydroxyl groups of 1.
The method for producing a cyanate ester according to the above (1), which is dissolved in an aqueous solution containing 5 to 5 equivalents of sodium hydroxide or potassium hydroxide. (5) The method for producing a cyanate ester according to the above (1), wherein the cyanogen halide is cyanogen chloride, and the used amount thereof is 1.5 to 5.5 equivalents to the hydroxyl group of the phenol. (6) After the completion of the reaction, a reaction solution containing a cyanate ester is mixed with water and an organic solvent capable of being separated from water, and an organic solvent layer containing a cyanate ester is separated from the mixed solution and collected. After washing the solvent layer with water, a poor solvent selected from secondary alcohols, tertiary alcohols and aliphatic hydrocarbons is brought into contact with the solvent layer to crystallize or precipitate the cyanate ester. )). (7) The production method according to the above (5), wherein the organic solvent capable of being separated from water is methyl isobutyl ketone, toluene or a mixture thereof. (8) The method according to (5) above, wherein the poor solvent is isopropyl alcohol, aqueous isopropyl alcohol, pentane, hexane, heptane, cyclopentane, cyclohexane, cyclopentane, or a mixture thereof.

[0007]

DETAILED DESCRIPTION OF THE INVENTION As the phenol used in the present invention, any phenols can be used as long as they satisfy the above general formula (I). It is necessary to be. That is, when a phenol, a hydroxide of an alkali metal and water are mixed such that the phenol becomes at least 1 part by weight with respect to 100 parts by weight of water, it is necessary to form a uniform solution. Specific examples of phenols include 4,4'-dihydroxydiphenyl,
3,3 ', 5,5'-tetramethyl-4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis (4-hydroxy-3-methylphenyl) methane, bis (4-hydroxy-3 -T-butylphenyl)
Methane, bis (4-hydroxy-3-i-propylphenyl) methane, bis (4-hydroxy-3,5-dimethylphenyl) methane, bis (2-hydroxy-3-t-
Butyl-5-methylphenyl) methane, bis (4-hydroxyphenyl) ethane, bis (4-hydroxy-3-
Methylphenyl) ethane, bis (4-hydroxy-3-
t-butylphenyl) ethane, bis (4-hydroxy-
3-i-propylphenyl) ethane, bis (4-hydroxy-3,5-dimethylphenyl) ethane, bis (2-
Hydroxy-3-t-butyl-5-methylphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (formula

[0008]

Embedded image It is represented by ), 2,2-bis (4-hydroxy-3-
Methylphenyl) propane, 2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3-i-propylphenyl) propane, 2,2-bis (4 -Hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (2-hydroxy-3-t-butyl-5-methylphenyl) propane,
2,2-bis (4-hydroxy-3-t-butyl-6-
Methylphenyl) propane, 2,2-bis (3-allyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) butane, 1,1-bis (4
-Hydroxy-3-methylphenyl) butane, 1,1-
Bis (4-hydroxy-3-t-butylphenyl) butane, 1,1-bis (4-hydroxy-3-i-propylphenyl) butane, 1,1-bis (4-hydroxy-
3,5-dimethylphenyl) butane, 1,1-bis (2
-Hydroxy-3-t-butyl-5-methylphenyl)
Butane, 1,1-bis (4-hydroxy-3-t-butyl-6-methylphenyl) butane, 2,2-bis (3-
Allyl-4-hydroxyphenyl) propane, 1,1-
Bis (3-allyl-4-hydroxyphenyl) butane,
1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxy-3-methylphenyl) cyclohexane, bis (4-hydroxyphenyl)
Sulfide, bis (4-hydroxy-3-methylphenyl) sulfide, bis (4-hydroxy-3-t-butylphenyl) sulfide, bis (4-hydroxy-3-
i-propylphenyl) sulfide, bis (4-hydroxy-3,5-dimethylphenyl) sulfide, bis (2-hydroxy-3-t-butyl-5-methylphenyl) sulfide, bis (4-hydroxyphenyl) sulfone, Bis (4-hydroxy-3-methylphenyl) sulfone, bis (4-hydroxy-3-t-butylphenyl) sulfone, bis (4-hydroxy-3-i-propylphenyl) sulfone, bis (4-hydroxy-3) , 5
-Dimethylphenyl) sulfone, bis (2-hydroxy-3-t-butyl-5-methylphenyl) sulfone, bis (4-hydroxyphenyl) ether, bis (4-hydroxy-3-methylphenyl) ether, bis (4 −
Hydroxy-3-t-butylphenyl) ether, bis (4-hydroxy-3-i-propylphenyl) ether, bis (4-hydroxy-3,5-dimethylphenyl) ether, bis (2-hydroxy-3-t) -Butyl-5-methylphenyl) ether, bis (4-hydroxyphenyl) carbonyl, bis (4-hydroxy-3-
Methylphenyl) carbonyl, bis (4-hydroxy-
3-t-butylphenyl) sulfide, bis (4-hydroxy-3-i-propylphenyl) carbonyl, bis (4-hydroxy-3,5-dimethylphenyl) carbonyl, bis (2-hydroxy-3-t-butyl) -5-methylphenyl) carbonyl and the like. Especially 2,2
-Bis (4-hydroxyphenyl) propane is industrially available.

The aqueous phenolate solution is prepared from phenols, alkali metal hydroxides and water. Examples of the alkali metal hydroxide include, but are not particularly limited to, sodium hydroxide, potassium hydroxide, lithium hydroxide and the like generally used in industry. When preparing an aqueous phenolate solution, the amount of the alkali metal hydroxide used is
The equivalent is preferably 1.5 to 5 equivalents to the hydroxyl group of the phenol, and more preferably 2.0 to 3.5 equivalents in order to increase the conversion to the cyanate ester.

As the cyanogen halide, cyanogen chloride or cyanogen bromide is used. The amount of cyanogen halide used is 1.5 to 1.5
5.5 equivalents, 0.8 equivalent to the equivalent of alkali metal hydroxide in order to suppress by-products of impurity imide carbonates.
It is desirable to use up to 3.0 equivalents.

The reaction between an aqueous phenolate solution of a phenolic alkali metal hydroxide and a cyanogen halide is carried out continuously or intermittently in a reaction vessel containing water serving as a solvent, in parallel through different ports. It is carried out by a method such as dripping. In this case, it is preferable to add a small amount of cyanogen halide in advance to water serving as a solvent in the reaction vessel. When cyanogen chloride is used, the reaction temperature is -30 to
20 ° C, more preferably -10 for safer handling
~ 15 ° C is preferred. When cyanogen bromide is used, -3
0-65 ° C is preferred.

After completion of the reaction, a reaction solution containing a cyanate ester is mixed with water and an organic solvent capable of being separated from water, and an organic solvent layer containing a cyanate ester is separated from the mixed solution and recovered. After the solvent layer solution is washed with water, it is contacted with a poor solvent selected from secondary alcohols, tertiary alcohols and aliphatic hydrocarbons to crystallize or precipitate cyanate ester, thereby obtaining purified cyanide. An acid ester can be obtained. In this case, when the poor solvent is brought into contact with the organic solvent layer solution to crystallize or precipitate the cyanate ester, the organic solvent layer solution can be concentrated in advance, if necessary. Concentration is performed by reducing the organic solvent layer solution under reduced pressure.
It is preferable to carry out the reaction by heating to a temperature of 20 ° C. or lower and distilling off the organic solvent. If the temperature is too high, trimerization starts, which is not preferable. Crystallization or precipitation is performed by cooling the organic solvent layer solution, adding it to the poor solvent, adding the poor solvent to the organic solvent layer solution, or mixing the organic solvent layer solution with the poor solvent. This is performed by a method such as cooling the liquid.

Examples of the organic solvent which can be separated from water include ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; aromatic solvents such as benzene, toluene and xylene;
Ether solvents such as diethyl ether and tetrahydrofuran, methylene chloride, chloroform, carbon tetrachloride, halogenated hydrocarbons such as chlorobenzene, nitrile solvents such as benzonitrile, nitro solvents such as nitrobenzene,
Ester solvents such as ethyl acetate and ethyl benzoate can be used. Among them, ketone solvents and aromatic solvents are preferable for obtaining a good yield, and among them, methyl isobutyl ketone and toluene are preferable. Most preferred is methyl isobutyl ketone.

As the poor solvent, secondary or tertiary alcohol solvents such as isopropyl alcohol, amyl alcohol and t-butyl alcohol, and aliphatic hydrocarbons such as benzene, toluene, xylene, hexane and petroleum ether are preferable. Alcohols may be mixed with water at any ratio. Further, the above-mentioned plural solvents may be arbitrarily mixed. Primary alcohols such as methanol and ethanol can be used, but are not preferred because the yield is reduced.

The cyanate ester produced by the method of the present invention is used as a thermosetting resin for sealing electronic parts, for laminates, for composite materials, for molding materials and for adhesives.

[0016]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 20 g (0.0865 mol) of 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsui Toatsu Chemicals) and 18.25 g (0.438 mol) of 96% caustic soda were uniformly dissolved in 500 g of water. Then, a phenolate solution was prepared, which was cooled to 5 ° C. In a reactor equipped with a thermometer, stirrer, dropping funnel and reflux condenser, add water 1
, And 7.97 g of cyanogen chloride (0.1 g).
30 mol). Into this reactor, the above-mentioned phenolate solution and 23.94 g (0.389 mol) of cyanogen chloride were simultaneously added dropwise over 40 minutes while maintaining the inside temperature at 0 to 10 ° C. And kept at the same temperature for 15 minutes. Next, 200 g of methyl isobutyl ketone was added to the reactor and the mixture was separated at 40 ° C., and the organic layer was washed twice with 100 g of water. Next, this organic layer is
After concentration under reduced pressure to 100 g, isopropyl alcohol (100 g) was added dropwise thereto, and the mixture was cooled to 2 ° C and stirred for 1 hour. The obtained slurry was filtered, washed with 10 g of isopropyl alcohol, and air-dried to obtain 19.73 g (yield: 82%) of a white crystalline cyanate ester having a melting point of 80 ° C.
When the product was analyzed by liquid chromatography (LC),
Unreacted starting materials, bisphenol and monocyanate, were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ion detected by potentiometric titration using silver nitrate is 10 ppm.
It was below.

Example 2 In Example 1, 19.01 g (0.31 mol) of cyanide chloride was added dropwise simultaneously with the aqueous phenolate solution.
The procedure was carried out under exactly the same conditions as above to obtain 19.3 g (yield: 80.3%) of cyanate ester as white crystals. When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 3 In Example 1, 29.27 g (0.470 mol) of cyanogen chloride was added dropwise simultaneously with the aqueous phenolate solution.
l) and 9 when preparing a phenolate solution.
21.90 g (0.526 mol) of 6% sodium hydroxide
The reaction was carried out under exactly the same conditions as above to obtain 19.28 g (yield: 80.1%) of cyanate ester as white crystals. When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 4 The procedure of Example 1 was repeated, except that toluene was used as an organic solvent capable of being separated from water after the reaction. 1
9.02 g was obtained (79% of yield). When the product was analyzed by LC, unreacted starting materials, bisphenol and monocyanate, were not detected. No imide carbonate generated by a side reaction was detected (purity 99+
%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Example 5 The procedure of Example 1 was repeated, except that 100 g of an 86% aqueous solution of isopropyl alcohol was used for crystallization and washing.
Was obtained (75% yield). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ion detected by potentiometric titration using silver nitrate is 10p
pm or less.

Example 6 The procedure of Example 1 was repeated, except that 110 g of heptane was used for crystallization and washing, to obtain 17.57 g of a white crystalline cyanate ester (yield 73%). When the product was analyzed by LC, unreacted raw materials of bisphenol and monocyanate were not detected. No imidocarbonate generated by a side reaction was detected (purity 99 +%). Chloride ions detected by potentiometric titration using silver nitrate were 10 ppm or less.

Comparative Example 1 20.0 g (0.0865 mol) of 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsui Toatsu Chemicals, Inc.)
l), 7.3 g of 96% caustic soda (0.1752 mol)
l) was added to 500 g of water, and the temperature was increased while stirring to 65 ° C. When 2,2-bis (4-hydroxyphenyl) propane was completely dissolved, the solution was cooled to 5 ° C or lower to prepare an aqueous phenolate solution. On the other hand, in a 1 L separable flask (reactor) connected with a stirring blade, a dropping funnel, and a reflux tube.
400 g of toluene was added and cooled to 5 ° C. under a nitrogen atmosphere. 16.9 cyanogen chloride was added to the cooled toluene solution.
ml (20.0 g 0.3252 mol) and 0.1 g (0.989 mmol) of triethylamine were added.
The mixture was stirred at 00 rpm. Next, the phenolate aqueous solution was added dropwise over 24 minutes while maintaining the reactor internal temperature at 5 ° C.
After dropping, the oil layer is taken out and washed twice with 100 g of water,
After concentration under reduced pressure, 100 g of isopropyl alcohol was added dropwise, and the mixture was cooled to 2 ° C and stirred for 1 hour. The obtained slurry was filtered, washed with 10 g of isopropyl alcohol, and air-dried. As a result of analysis by LC, the yield of the obtained dicyanate compound based on bisphenol was as low as 40%, and it was found that 5% of unreacted monocyanate compound and 2% of by-product imide carbonate were contained as impurities.

Comparative Example 2 In a reactor equipped with a thermometer, a stirrer, a dropping funnel and a reflux condenser, 2,2-bis (4-hydroxyphenyl) propane (manufactured by Mitsui Toatsu Chemicals, Inc.) under a nitrogen atmosphere. 400g
(1.76 mol), 933 g of acetone and 258.9 g (4.21 mol) of cyanogen chloride were charged, dissolved at room temperature, and then cooled to 0 ° C. Next, triethylamine 37
2.8 g (3.68 mol) was added dropwise at 0 to 6 ° C over 1 hour, and the mixture was kept at the same temperature for 1 hour. Next, the content of the obtained reactor was dissolved and crystallized in 5 L of water to obtain yellow-white crystals. This was washed with 2 L of water and then dried under reduced pressure to obtain 246 g of a pale yellow crystal cyanate ester having a melting point of 76 to 78 ° C. The yield was 61%. As a result of gas chromatography (GC) analysis, the impurity diethylcyanoamide 2.2 was obtained.
% Was detected. In addition, 81 by potentiometric titration using silver nitrate
0 ppm of chloride ions were detected.

As is clear from the examples, preferably,
By using an amount of caustic soda in excess of the hydroxyl equivalent of phenol and bringing cyanogen chloride and an aqueous phenolate solution into contact with each other in an aqueous solution, a high-purity dicyanate could be obtained in high yield. As shown in the comparative example, the organic solvent /
In a method in which a small amount of a tertiary amine is used by reacting with a mixed system of water, it is difficult to remove the imide carbonate-based compound as a by-product as an impurity, and the method using triethylamine as a base is low in volatility. Liquid impurity dialkyl cyanoamide is by-produced, and it is difficult to obtain cyanate with high purity in any case. Since the present invention uses only water as a solvent in the reaction, it can be said that the present invention is an excellent process which has a very low risk and can be carried out on an industrial scale.

[0025]

According to the production method of the present invention, a high-purity cyanate ester which is safe and simple in terms of process without using dialkyl cyanoamide as a by-product while using an alkali metal salt of phenols as a raw material. Is obtained in high yield.

Claims (8)

[Claims] (1) The following general formula (I): (I) (wherein, A is each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, X is a single bond,
To 20, an organic group, a carbonyl group, a sulfone group, a divalent sulfur atom or an oxygen atom, and I represents an integer of 0 or more and 4 or less. A) a phenolate aqueous solution prepared from phenols, alkali metal hydroxides and water represented by the formula (1), and a cyanogen halide, wherein the reaction is carried out by adding the reaction to water in parallel. Method. 2. The method for producing a cyanate ester according to claim 1, wherein the phenolate of a phenol alkali metal hydroxide has a solubility of 1% or more in water. 3. The method for producing a cyanate ester according to claim 1, wherein the phenol is represented by the following formula. Embedded image 4. The phenolate aqueous solution of an alkali metal hydroxide of phenols is obtained by dissolving phenols in an aqueous solution containing 1.5 to 5 equivalents of caustic soda or caustic potash based on the hydroxyl groups. The method for producing a cyanate ester according to the above. 5. The method according to claim 1, wherein the cyanogen halide is cyanogen chloride, and the amount of the cyanogen halide is 1.5 to 5.5 based on the hydroxyl group of the phenol.
The method for producing a cyanate ester according to claim 1, which is an equivalent. 6. After completion of the reaction, a reaction solution containing a cyanate ester is mixed with water and an organic solvent capable of being separated from water, and an organic solvent layer containing a cyanate ester is separated from the mixed solution and collected. After washing the organic solvent layer with water, secondary alcohols,
The method for producing a cyanate ester according to claim 1, wherein a poor solvent selected from tertiary alcohols and aliphatic hydrocarbons is brought into contact with the mixture to precipitate or precipitate the cyanate ester. 7. The method according to claim 6, wherein the organic solvent capable of being separated from water is methyl isobutyl ketone, toluene or a mixture thereof. 8. The method according to claim 6, wherein the poor solvent is isopropyl alcohol, aqueous isopropyl alcohol, pentane, hexane, heptane, cyclopentane, cyclohexane, cyclopentane or a mixture thereof.