JPH02123122A - Reduction in hydrolyzable chlorine - Google Patents

Abstract

PURPOSE:To reduce the title chlorine in crude epoxy resin almost without forming a gelatinous substance as a by-product by bringing a crude epoxy resin into contact with a hydrous alcohol, separating and removing an alkali metal halide and bringing the epoxy resin into contact with an alkali metal hydroxide. CONSTITUTION:A polyhydric alcohol (preferably bisphenol A, bisphenol AD and/or hydroquinone) and an epihalohydrin are successively subjected to ring formation reaction and dehydrohalogenation reaction to form an alkali metal halide as a by-product, which is removed. The prepared crude epoxy resin is brought into contact with a hydrous alcohol, the system is separated into two layers, the hydrous alcohol layer is separated, removed and then the epoxy resin is brought into contact with an aqueous solution of alkali metal hydroxide to reduce hydrolyzable chlorine to <=0.01wt.% content.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for reducing hydrolyzable halogen, particularly hydrolyzable chlorine. The present invention relates to a method for reducing hydrolyzable halogen 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 11 equivalents. However,
In the crude epoxy resin obtained in this way, a trace amount of chlorohydrin ether group is ring-closed, not only when the equivalent ratio of sodium hydroxide used is less than 10, but even when it is more than 10. It was not removed and remains as it is.

If a large amount of such hydrolyzable chlorine is contained in an epoxy resin, there are disadvantages such as poor electrical properties of the cured product. In other words, hydrolyzable chlorine has negative effects such as deterioration of 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. conditions.

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 reclosing step is provided, and this reclosing process generally involves distilling off the excess amount of shrimp halohydrin and then adding aromatic compounds such as l-luene and xylene as needed. Dilute with a ketone solvent such as γ8 medium or methyl isobutylketone to a concentration of about 1 to 50.
This is carried out by adding about 1.1 to 10 times the amount of alkali metal hydroxide by weight to the remaining hydrolyzable chlorine and heating the mixture to about 60 to 100°C. However, when carrying out this re-ring closure treatment in a solvent, it is necessary to reduce the content of hydrolyzable chlorine to 0.1% by weight or less, especially 0.05% by weight or less, which requires very strict conditions. , but it is difficult.

Furthermore, if the re-ring closure treatment is performed 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 a large amount of gel-like material will be produced as a by-product. let 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 for reducing the content of hydrolyzable chlorine by exchanging residual herohydrin ether groups with glycidyl ether groups. However, looking at the description of the example, the content is at least 0.0
Only a triple weight product can be obtained, and in 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 deteriorated.

<Problems to be Solved by the Invention> The present inventors have devised a technology that allows the quaternary ammonium salt to be bonded to a crude epoxy resin without using the quaternary ammonium salt as described above, and without producing a gel-like substance as a by-product. The purpose is to find a method for reducing the hydrolyzable halogen content, especially chlorine.

As a result of intensive research, the present inventors brought a crude epoxy resin into contact with a hydrous alcohol, separated the system into two layers, and then separated and removed the hydrous alcohol layer. Then, if necessary, after distilling off the alcohol remaining in the resin, the resin is brought into contact with an alkali metal hydroxide, thereby effectively reducing the hydrolyzable chlorine content without producing a gel-like substance as a by-product. I discovered that.

That is, the present invention provides a compound obtained by sequentially subjecting polyhydric phenols and ebihalohydrin to a ring-opening reaction and a dehydrohalogenation reaction in the presence of an aqueous alkali metal hydroxide solution to remove by-produced alkali metal halides. The crude epoxy resin is brought into contact with a hydrous alcohol, and after the system is separated into two layers, the hydrous alcohol layer is separated and removed, and then, if necessary, after distilling off the alcohol remaining in the resin, an alkali metal hydroxide is added. Provided is a method for reducing hydrolyzable halogen contained in a crude epoxy resin, the method comprising contacting the crude epoxy resin with an aqueous solution.

The polyhydric phenol used in the present invention is bisphenol A
1-bisphenol AD and/or hydroquinone are preferred.

And in the crude polyhydric phenol-based epoxy resin containing 0.1 to 5.0% by weight of hydrolyzable chlorine,
This content is preferably 0.01% by weight or less.

Further, it is preferable that the hydrous alcohol is selected from n-propanol and isopropanol.

The hydrous alcohols are for crude epoxy resin,
It is preferable to use it in a weight ratio of 0.5 to 20.

The alcohol content in the hydrous alcohol is preferably 10 to 70% by weight.

Further, it is preferable that the temperature at which the crude epoxy resin is brought into contact with the hydrous alcohol is 50 to 120°C, and the temperature at which the crude epoxy resin is brought into contact with the aqueous alkali metal hydroxide solution is 50 = 150°C.

The present invention will be explained in detail below.

The crude epoxy resin to which the method of the present invention is applied is obtained by sequentially subjecting polyhydric phenols and shrimp halohydrin to a ring-opening reaction and a dehydrohalogenation reaction.

Examples of polyhydric phenols include QL ring polyhydric phenols such as resorcinol and hydroquinone, or 2.2-
Bis(4-hydroxyphenyl)propane [bisphenol A], bis(4-hydroxyphenyl)methane [bisphenol Fl, 1.1-bis(4-hydroxyphenyl)ethane [bisphenol AD] bis(4-hydroxyphenyl)sulfono, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 1,1-bis(4
-hydroxyphenyl)-1-phenylethane, 2゜2
-bis(3,5-dibromo-4-hydroxyphenyl)
Examples include polycyclic polyhydric phenols such as propane, phenol novolac, and cresol novolac.

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

Examples of the shrimp herohydrin to be reacted with this polyhydric phenol include epichlorohydrin and those having an argyl substituent, shrimp bromohydrin, and the like, with epichlorohydrin being particularly preferred.

These polyhydric phenols and shrimp herohydrin can both be used singly or in combination of two or more, as shown in the examples above.

The crude epoxy resin obtained after distilling off the hydroxide and herochthrin is the one that contains about 0.1 to 5.0% by weight of hydrolyzable halogen in a bound state.

If unreacted shrimp helohydrin is present in these crude epoxy resins, it is removed by distillation or the like, and then alkali metal halides such as common salt and other water-soluble impurities are removed by washing with water or the like.

Next, the obtained crude epoxy resin is brought into contact with a hydrous alcohol.

As the hydrous alcohol, a mixture of water and alcohols such as methanol, ethanol, isopropyl alcohol, and propyl alcohol is used. Particularly preferred are n-proper tools and in-proper tools. These resins can be easily separated from the hydrous alcohol.

These hydroalcohols are used in a weight ratio of 0.5 to 2.0 with respect to the crude epoxy resin. Preferably,
It is used by adjusting the weight ratio to 0.6 to 1.0. Furthermore, the alcohol content in the hydrous alcohols is 10 to 70
It is preferably 40 to 60% by weight, more preferably 40 to 60% by weight.
It is more preferable that This is to facilitate separation of the resin and hydrous alcohol.

The contact between the crude epoxy resin containing hydrolyzable halogen, especially chlorine, and the hydrous alcohol is carried out by heating and stirring at a temperature of 50 to 120°C, preferably 80 to 100°C, for about 0.5 to 2 hours. It's good to be able to do it.

After stirring, the mixture is allowed to stand still, and the hydrous alcohol layer to be separated is separated and removed. If necessary, a small amount of alcohol remaining in the resin layer is recovered by distillation.

Then, if necessary, the mixture is diluted with a hydrophobic solvent, for example, an aromatic hydrocarbon such as toluene or xylene, or a ketone such as methyl ethyl ketone, and then an aqueous alkali metal hydroxide solution is added, followed by heating and stirring.

Examples of the alkali metal hydroxide aqueous solution include sodium hydroxide aqueous solution and potassium hydroxide aqueous solution. 8 liquid is preferably used.

Moreover, a phosphate, a borate, a carboxylate, or the like may coexist in this aqueous alkali metal hydroxide solution.

The content of alkali metal hydroxide is generally about 1 atom per hydrolyzable halogen atom remaining in the crude epoxy resin.
Using an alkali metal hydroxide that is ~10 times equivalent,
It is about 1-30% by weight, preferably about 3-15% by weight.
It is used after adjusting the concentration to .

The epoxy resin washed with a hydrous alcohol and the alkali metal hydroxide are brought into contact at a temperature of 50 to 150°C, preferably 70°C.
This is carried out by heating and stirring at a temperature of 0 to 100°C for about 0.5 to 3 hours.

After that, if the reaction system is solvent-free, the above hydrophobic solvent is added here, the aqueous layer is separated and removed, and in some cases, a neutralizing agent is added for neutralization and washing, and then the hydrophobic solvent is removed. death,
By performing f-filtration as necessary, purified epoxy resin can be easily obtained.

<Example> The present invention will be specifically described below based on Examples.

(Example 1) After a ring-opening reaction between bisphenol A and epichlorohydrin, a dehydrochlorination reaction using lithium hydroxide was subsequently performed. Unreacted epichlorohydrin was distilled off under reduced pressure, and the by-produced sodium chloride was then washed away. As a result, a crude epoxy resin containing 1.3c+ffi amount of hydrolyzable chlorine and mainly consisting of bisphenol A diglycidyl ether was obtained. Obtained.

100 g of isopropanol is added to 300 g of the obtained crude epoxy resin and heated at 95° C. for 30 minutes.

Furthermore, 150 g of water was added to this mixed solution and stirred for 5 minutes at the same temperature. Thereafter, the separated hydroalcohol layer is removed, and the solvent in the organic layer is distilled off under reduced pressure. 6 wt% sodium hydroxide solution in this organic layer? A mixed solution of 73 g (2.2 times equivalent to hydrolysable chlorine) and 1.0 g of 85% heavy phosphoric acid (molar ratio of phosphoric acid to sodium hydroxide charged 0.033) was added, and the mixture was heated to 1 at 95°C.
The mixture was heated for 20 minutes to perform a re-ring closure reaction. The product was then mixed with 250 g of xylene 1. : The aqueous layer was dissolved and separated, the organic layer was neutralized with a 10% by weight aqueous sodium phosphate-hydrogen solution, and the aqueous layer was separated and removed.

Xylene was distilled off under reduced pressure and subjected to '/F iM, to obtain an epoxy resin (epoxy fi 188) with properties and Kel formation as shown in Table 1 below.

(Comparative Example 1) A crude epoxy resin was prepared in the same manner as in Example 1, and a mixed solution of sodium hydroxide and phosphoric acid was directly added without adding isopropanol.

As shown in Table 1, the content of hydrolyzable chlorine in the produced epoxy resin increased.

(Comparative Example 2) A crude epoxy resin was prepared in the same manner as in Example 1, and after distilling off water as a solvent under reduced pressure without adding isopropanol to the crude epoxy resin, sodium hydroxide and phosphoric acid were added. A mixed solution of was added. A large amount of gel-like material was observed to be generated during the xylene dissolution stage.

(Example 2) In Example 1, 200 g of water and 100 g of isopropanol were added to 300 g of the crude epoxy resin containing salt after the dehydrochlorination reaction, and the mixture was heated at 85° C. for 30 minutes. Thereafter, the separated aqueous layer was removed to obtain an organic layer.

The solvent contained in 250 g of this crude epoxy resin was distilled off under reduced pressure, and then a mixed solution of sodium hydroxide and phosphoric acid was added.The following steps were carried out in the same manner as in Example 1. The results are shown in Table 1.

By this method, it is possible to create an epoxy resin with a low content of hydrolyzable chlorine.

(Comparative Example 3) The same procedure as in Example 2 was repeated except that no isopropanol was used, and the hydrolysis +' was attempted to produce an epoxy resin with a low chlorine content. At this stage, a large amount of gel-like substance 1τ was observed to be generated.

Table* and dried gel weight Nigel layer of 300 mesh Tef ℃ 1
After filtration with a filter made of carbon fiber, washed with acetone, water, and acetone in that order for 41 minutes, dried at 60°C for 611ii, and further dried at 80°C for 6 hours under reduced pressure.
g) is converted into 1 H of produced resin.

<Effects of the Invention> According to the method of the present invention, by subjecting the hydrolyzable halogen, especially chlorine, contained in the crude epoxy resin to a re-ring-closing reaction, its content can be reduced without producing a gel-like substance by-product. The amount can be reduced to 0.01% by weight or less.

Claims (1)

[Claims] (1) In the presence of an aqueous alkali metal hydroxide solution, polyhydric phenols and epihalohydrin are sequentially subjected to a ring-opening reaction and a dehydrohalogenation reaction to remove by-produced alkali metal halides. In the crude epoxy resin, the obtained crude epoxy resin is brought into contact with a hydrous alcohol, and after the system is separated into two layers, the hydrous alcohol layer is separated and removed, and then brought into contact with an aqueous alkali metal hydroxide solution. A method for reducing contained hydrolyzable halogen. (2) The method for reducing hydrolyzable halogen according to claim 1, wherein the polyhydric phenol is bisphenol A, bisphenol AD and/or hydroquinone. (3) In the crude polyhydric phenol-based epoxy resin containing 0.1 to 5.0% by weight of the hydrolyzable halogen, the content is 0.01% by weight or less. Method for reducing hydrolyzable halogen. (4) The method for reducing hydrolyzable halogen according to any one of claims 1 to 3, wherein the hydrous alcohol is n-propanol and isopropanol. (5) The method for reducing hydrolyzable halogen according to any one of claims 1 to 4, wherein the hydrous alcohol is used at a weight ratio of 0.5 to 2.0 with respect to the crude epoxy resin. (6) The alcohol in the hydrous alcohol is 10 to
The method for reducing hydrolyzable halogen according to any one of claims 1 to 5, wherein the amount is 70% by weight. (7) The method for reducing hydrolyzable halogen according to any one of claims 1 to 6, wherein the temperature at which the hydrous alcohol is brought into contact with the crude epoxy resin is 50 to 120°C. (8) The method for reducing hydrolyzable halogen according to any one of claims 1 to 7, wherein the temperature at which the aqueous alkali metal hydroxide solution is brought into contact is 50 to 150°C.