JPH02175714A - Reduction of hydrolyzable chlorine content - Google Patents

Abstract

PURPOSE:To reduce the hydrolyzable chlorine content and to prevent a gel-like substance from forming as a by-product by subjecting the hydrolyzable chlorine in a crude polyphenol epoxy resin again to ring closure. CONSTITUTION:A polyphenol (e.g. bisphenol A) and an epihalohydrin are subjected successively to ring opening and dehydrohalogenation in the presence of an alkali metal hydroxide and/or a catalyst to obtain a crude polyphenol epoxy resin of a hydrolyzable chlorine content of 0.1-5.0wt.%. This epoxy resin is washed with water at room temperature to 100 deg.C until the total content of the water-soluble organic compounds to be removed is reduced to 1.2g/kg of the formed resin, brought into contact with an aqueous solution containing 1-30wt.% alkali hydroxide in an amount 1-10 times as large as that of the remaining hydrolyzable chlorine atoms in the crude epoxy resin and subjected to ring closure again at 50-150 deg.C to obtain a polyphenol epoxy resin of a hydrolyzable chlorine content <=0.01wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for reducing hydrolyzable chlorine. More specifically, with almost no by-product of Kel-like substances,
The present invention relates to a method for reducing hydrolyzable chlorine contained in a bound state in a crude polyhydric phenol-based epoxy resin.

<Prior art> The method for producing epoxy resin from polyhydric phenols and ebihalohydrin basically involves opening the polyhydric phenols and ebihalohydrin in the presence of a catalyst such as an alkali metal hydroxide or an onium salt. A ring reaction is carried out, and there-
The helohydrin ether produced is then subjected to a dehydrohalogenation reaction with an alkali metal hydroxide to form an epoxy group.

In this dehydrohalogenation reaction, epihalohydrin, generally epichlorohydrin, is used in excess of the phenolic hydroxyl group, and alkali metal hydroxide, generally sodium hydroxide, is used in an excess of 0.00% per equivalent of the phenolic hydroxyl group.
It is used in a proportion of 9 to 1.1 equivalents. However,
The crude epoxy resin obtained in this way contains trace amounts of chlorohydrin, not only when the equivalent ratio of sodium hydroxide used is less than 1.0, but even when it is more than 1.0. The ether group is not ring-closed and remains as it is.

When an epoxy resin contains a large amount of rohydrin ether type, that is, hydrolyzable chlorine, there are disadvantages such as poor electrical properties of the cured product. In other words, hydrolyzable chlorine has negative effects such as a decrease in electrical insulation and corrosion of lead wires, so it is absolutely necessary to keep the content low, especially when it is used as a raw material for encapsulating integrated circuits that use semiconductors. This is the condition. Furthermore, the presence of hydrolyzable chlorine also brings about drawbacks such as lowering the curing speed when amines are used as curing agents or curing accelerators for epoxy resins.

Therefore, it is strongly desired to reduce the hydrolyzable chlorine content in epoxy resins, and as a countermeasure, it is considered to further increase the amount of alkali metal hydroxide used in the dehydrohalogenation reaction. However, this only promotes the decomposition of epichlorohydrin and side reactions, but does not effectively cause the remaining chlorohydrin ether group to undergo a reclosing reaction.

For this purpose, a separate re-ring-closing step is provided, but this re-ring-closing treatment is generally carried out after distilling off the excess amount of shrimp halohydrin, and then using an aromatic solvent such as toluene, xylene or methyl Dilute with a ketone solvent such as isobutyl ketone to a concentration of about 1 to 50% by weight.
of alkali metal hydroxide is added in an equivalent amount of about 1.1 to 10 times the remaining hydrolyzable chlorine.
It is carried out by heating to 0 to 100°C. However, when carrying out this re-ring closure treatment in a solvent, very strict conditions must be adopted to reduce the content of hydrolyzable chlorine to 0.1% by weight or less, especially 0.05% by weight or less. However, it is difficult to do so.

Furthermore, if the re-ring closure treatment is carried out in the absence of a solvent, if an excessive amount of alkali metal hydroxide is used, the content of hydrolyzable chlorine will be reduced, but this time the problem of large amounts of gel-like substances produced as by-products will occur. generate. The generation of such gel-like substances not only complicates the post-treatment process but also leads to a decrease in the yield of epoxy resin, and therefore, it is strongly desired to suppress the generation of gel-like substances.

Various treatment methods have been proposed to date to effectively reduce the content of hydrolyzable chlorine. for example,
In the method described in JP-A-57-31922, a crude epoxy resin produced from polyhydric phenols and shrimp halohydrin is mixed with an aqueous alkali metal hydroxide solution containing a quaternary ammonium salt and a hydrophobic solvent. Processed with
A method is described in which the content of hydrolyzable chlorine is reduced by converting residual herohytrine ether groups into glycidyl ether groups. However, looking at the description of the example, the content is at least 0.03
% by weight, and with this treatment method, there is a possibility that nitrogen content may remain in the epoxy resin, and there is a concern that the quality of the resin will be degraded.

In addition, in Japanese Patent Publication No. 52-12701, 0.05~
Bisphenol A containing 2% by weight of hydrolyzable chlorine
By treating diglycidyl ether with an alkaline dehydrochlorination agent in an amount of 1 to 10 times equivalent to this hydrolyzable chlorine in the presence of an alcohol solvent or an alcohol-aromatic hydrocarbon mixed solvent, its content can be reduced. The amount is 0.03
A method for reducing the amount to below % by weight is described. This method can reduce hydrolyzable chlorine under relatively mild conditions, but since water-soluble solvents are difficult to separate from water, these solvents may be mixed into wastewater, resulting in wastewater treatment. becomes complicated and increases manufacturing costs.

<Problems to be Solved by the Invention> The present inventors have solved the problem without using the above-mentioned quaternary ammonium salts, without using solvents such as alcohol, and with almost no by-product of gel-like substances. The purpose of the present invention is to find a method for reducing hydrolyzable chlorine contained in a bound state in a crude epoxy resin without accompanying the present invention.

Means for Solving the Problems> Therefore, the present invention provides a compound obtained by sequentially subjecting polyhydric phenols and shrimp halohydrin to a ring-opening reaction and a dehydrohalogenation reaction in the presence of an alkali metal hydroxide and/or a catalyst. When the by-product alkali metal halide is removed by water washing from the crude polyhydric phenol-based epoxy resin, the total amount of water-soluble organic compounds removed at the same time is 1.2 g/(1 kg of produced resin) as TOC (total organic carbon). ) A method for converting hydrolyzable chlorine into other forms is provided, which comprises washing with water until the chlorine reaches the above level, and then contacting the chlorine with an aqueous alkali metal hydroxide solution.

Further, it is preferable that the polyhydric phenol is bisphenol A, bisphenol AD or hydroquinone.

The present invention is preferably applied to a crude polyhydric phenol-based epoxy resin having a hydrolyzable chlorine content of 0.1 to 5.0% by weight, and the content is preferably 0.01% by weight or less.

Further, the washing temperature during the water washing is room temperature to 100°C.
It is good to be.

And it is preferable that the temperature at which it is brought into contact with the aqueous alkali metal hydroxide solution is 50 to 150°C.

The present invention will be explained in detail below.

In the production method of the present invention, polyhydric phenols and shrimp halohydrins are sequentially subjected to a ring-opening reaction and a dehydrohalokenation reaction in the presence of an alkali metal hydroxide and/or a catalyst, thereby producing a crude epoxy resin and by-products. Then, an alkali metal halide is obtained.

Examples of polyhydric phenols include monocyclic polyhydric phenols such as resorcinol and hydroquinone; ADI, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)1-phenylethane, 2,2-bis( 3,
Examples include polycyclic polyhydric phenols such as 5-dibromo-4-hydroxyphenyl)propane, phenol novolak, and cresol novolak.

Particularly suitable are bisphenol A1 bisfuninol AD, hydroquinone, and the like. These polyhydric phenols may be used in combination of two or more.

Examples of the shrimp halohydrin to be reacted with this polyhydric phenol neck include epichlorohydrin and those having an alkyl substituent thereof, shrimp bromohydrin, etc., and epichlorohydrin is particularly preferred.

These polyhydric phenols and shrimp halohydrin are each one type or 2f! from the above examples! A mixture of one or more can be used.

The crude epoxy resin obtained after distilling off shrimp halohydrin is one that contains about 0.1 to 5.0% by weight of hydrolyzable chlorine in a bound state.

If unreacted ebihalohydrin is present in these crude epoxy resins, it is removed by distillation or the like, and then alkali metal halides such as sodium chloride and other water-soluble organic compounds are removed by washing with water or the like.

At this time, since the water-soluble organic compound is a precursor of a gel-like substance that will be produced as a by-product later, it is better to remove it as much as possible. The present invention is characterized in that the total amount of water-soluble organic compounds to be removed is 1.2 g/(tkg of produced resin) or more as TOCffi (total organic carbon amount) by water washing.

The above TOC amount can be easily achieved by adjusting the number of washings and/or the amount of washing water. For example, if the amount of washing water is equal to that of the resin, one washing is sufficient.

The washing of the crude epoxy resin containing hydrolyzable chlorine with water is carried out at room temperature to 100°C, preferably from 80 to 95°C.
This is preferably carried out by heating and stirring at a temperature of . This is because water-soluble organic compounds become most easily soluble in water within this temperature range.

After the stirring and standing, the aqueous layer is separated and removed.

The crude epoxy resin thus washed is brought into contact with an aqueous alkali metal hydroxide solution, preferably an aqueous sodium hydroxide solution, to carry out a dehydrohalogenation reaction. The alkali metal hydroxide is generally used in an amount of about 1 to 10 times equivalent to 1 atom of hydrolyzable chlorine remaining in the crude epoxy resin, and preferably about 1 to 30% by weight. is used at a concentration of about 3 to 15% by weight.

Further, a catalyst or the like may be allowed to coexist with the alkali metal hydroxide. The temperature at this time is about 50 to 150°C, preferably about 70 to 100°C, and the mixture is heated and stirred for about 0.5 to 3 hours.

After separating and removing the aqueous layer, if necessary, dilute with a hydrophobic solvent such as aromatic hydrocarbons such as toluene and xylene, or ketones such as methyl ethyl ketone, and then add an aqueous alkali metal hydroxide solution. , may be heated and stirred.

After that, the aqueous layer is separated and removed again, and if necessary, a neutralizing agent is added to neutralize it. After washing, the hydrophobic solvent is removed, and if necessary, the hydrolyzable chlorine content is reduced to zero. ．．
Purified epoxy resins of up to 0.01% by weight can be obtained.

<Examples> The present invention will be described in more detail below based on Examples.

(Example 1) After ring-opening reaction of bisphenol A [2,2-bis(4-hydroxyphenyl)propane] and epichlorohydrin in the presence of a sodium hydroxide catalyst, a subsequent dehydrochlorination reaction using sodium hydroxide was performed. I did it. Unreacted epichlorohydrin was distilled off under reduced pressure to obtain crude epoxy resin A.

Next, the by-produced sodium chloride was removed by washing with water to obtain a crude epoxy resin B containing 1.39% by weight of hydrolyzable chlorine and mainly consisting of bisphenol A diglycidyl ether.

Next, 8250 g of the crude epoxy resin was washed with water.
250 g of water was added to the mixture, and the mixture was heated and stirred at 95° C. for 30 minutes. After standing still, the aqueous layer was separated and removed. After performing this water washing operation once, next, a 6% by weight sodium hydroxide solution (2.2 times equivalent to hydrolyzable chlorine) was added to the crude epoxy resin, and the mixture was heated and stirred at 95°C for 120 minutes. A reclosing reaction was performed. Then, the product was dissolved in 250 g of xylene, the separated aqueous layer was removed, and the organic layer was reduced to 10% by weight.
Neutralized with aqueous sodium hydrogen phosphate solution.

Under reduced pressure, xylene was distilled off and filtered from the organic layer, and the results were shown in Table 1 below.
A product epoxy resin having the property values shown in was obtained.

(Example 2.3) An epoxy resin was produced using the same method as in Example 1, except that the above-mentioned water washing operation was performed twice in Example 2 and three times in Example 3. Table 1 shows each property value.

(Comparative Example 1) An epoxy resin was produced by performing the same procedure as in Example 1, except for washing the crude epoxy resin B with water, and performing the following operations in the same manner as the re-ring closure reaction. Table 1 shows its property values.

Table 1) Dry gel weight After fA of the Nigel layer with a 300 mesh Teflon filter, it was washed with acetone, water, and acetone in that order, dried at 60℃ for 6 hours, and further dried under reduced pressure at 80℃ for 6 hours. The weight (g) of the produced resin 1
This is the value converted per kg.

This dry gel weight is the amount of gel generated due to the reclosing reaction of the treated epoxy resin, so the smaller the value, the better.

2) TOC amount: TOC in the aqueous layer of crude epoxy resin A during sawing and T in the aqueous layer of crude epoxy resin B during washing.
This is the value obtained by converting the total amount of OC per 1 kg of produced resin. The larger this value is, the more by-products in the epoxy resin are reduced.

<Effects of the Invention> According to the method of the present invention, by subjecting the hydrolyzable chlorine contained in the crude epoxy resin to a ring-closing reaction, by-products in the epoxy resin are reduced, and the accompanying gel-like It is possible to suppress the by-product of substances and reduce the content of hydrolyzable chlorine to 0.01% by weight or less.

Written by Mitsune Teito (spontaneous) 1. Indication of the case Patent Application No. 332518 of 1988 2. Name of the invention Method for reducing hydrolyzable chlorine 3. Person making the amendment Relationship to the case Name of patent applicant Name (588) Mitsui Petrochemical Industries Co., Ltd. 4,
Agent 101 Telephone 864-4498 Address
Chiyoda Iwamoto Building, 3-2-2 Iwamotocho, Chiyoda-ku, Tokyo
Column 6 of “Detailed Description of the Invention” of the 4th floor specification, contents of amendment (1) “Chlorhydrin ether type” written in page 4, line 5 of the specification is corrected to “chlorohydrin ether group” do.

(2) “Aforesaid” and “aforesaid” in line 12, page 15 of the specification.
``From crude epoxy resin B'' is added between ``of the water washing operation''.

Claims (5)

[Claims] (1) In the presence of an alkali metal hydroxide and/or a catalyst, polyhydric phenols and epihalohydrin are sequentially added,
When the by-product alkali metal halide is removed by water washing from the crude polyhydric phenol-based epoxy resin obtained by ring-opening reaction and dehydrohalogenation reaction, the total amount of water-soluble organic compounds removed at the same time is TOC (total organic A method for reducing hydrolyzable chlorine, which comprises washing with water until the carbon content reaches 1.2 g/(1 kg of produced resin) or more, and then contacting with an aqueous alkali metal hydroxide solution. (2) Claim 1 wherein the polyhydric phenol is bisphenol A, bisphenol AD or hydroquinone.
The method for reducing hydrolyzable chlorine described in . (3) The method according to claim 1 or 2, wherein the hydrolyzable chlorine content is applied to a crude polyhydric phenol-based epoxy resin having a content of 0.1 to 5.0% by weight, and the content is 0.01% by weight or less. The method for reducing hydrolyzable chlorine described above. (4) The washing temperature during the water washing is room temperature to 100°C.
The method for reducing hydrolyzable chlorine according to any one of claims 1 to 3. (5) The method for reducing hydrolyzable chlorine according to any one of claims 1 to 4, wherein the temperature during contact with the aqueous alkali metal hydroxide solution is 50 to 150°C.