JPS6316408B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a novel manufacturing method for obtaining a polyfunctional epoxy resin with high purity and high yield. The production method of the present invention is particularly useful for polyfunctional epoxy resins having trifunctionality or more, and the polyfunctional epoxy resin obtained by carrying out the present invention provides a cured product with excellent heat resistance and water resistance.

[Prior art]

Epoxy resins have been used in a wide range of applications such as adhesives, paints, sealants for electronic parts, and matrix resins for carbon fiber-reinforced plastics due to their excellent mechanical properties, electrical properties, adhesive properties, and heat resistance. Among these, matrix resins for carbon fiber reinforced plastics are mainly used from the viewpoint of heat resistance.
Polyfunctional epoxy resins such as polyglycidyl ether of phenol novolak and tetraglycidyldiaminodiphenylmethane are often used.

There are two well-known methods for producing epoxy resins: a one-stage method and a two-stage method. In other words, taking the method for producing polyglycidyl ether as an example, the former method involves dissolving a polyhydric phenol compound in an excess amount of epichlorohydrin of 3 to 7 moles per equivalent of phenolic hydroxyl group, and then dissolving the polyhydric phenol compound per equivalent of phenolic hydroxyl group. This is a method for producing an epoxy resin by dropping an aqueous solution of 0.9 to 1.2 mol of sodium hydroxide to simultaneously perform an epichlorohydrin addition reaction and an HCl removal reaction. On the other hand, in the latter method, the addition reaction and the dehydrochlorination reaction are carried out in two steps: first, the raw material polyphenol compound is dissolved in an excess of 3 to 7 moles of epichlorohydrin per equivalent of phenolic hydroxyl group; A quaternary ammonium salt such as ammonium chloride is added thereto as a catalyst to allow the addition reaction to proceed.
The phenolic hydroxyl group of the phenolic compound as the raw material for the chlorohydrin ether produced in this way
In this method, 0.8 to 1.2 moles of sodium hydroxide aqueous solution per equivalent is added dropwise to perform a dehydrochlorination reaction to produce an epoxy resin. When used in applications that require higher properties, especially heat resistance and water resistance, epoxy resins must be of high quality.
When comparing the two methods, it is known that the latter two-step method is superior in that an epoxy resin with particularly high purity and low chlorine content can be obtained. However, even when a two-stage method is used to produce a trifunctional or higher-functional epoxy resin, the yield and purity decrease, and in particular, a decrease in heat resistance due to the decrease in purity poses a problem.

[Object of the present invention]

In view of the shortcomings of the prior art, the inventors of the present invention have conducted extensive studies on a method for producing a highly purified epoxy resin at a high yield, and as a result, they have discovered the present invention.

[Configuration of the present invention]

That is, the present invention relates to a method for producing an epoxy resin through the following three steps.

(1) A method for producing a polyfunctional epoxy resin characterized by comprising at least the following steps.

General formula of polyhydric phenols in the presence of a catalyst
The step of adding an epihalohydrin compound as shown in (A) X: Br or Cl R: H or CH ₃ Step of washing the reaction solution obtained in the above step with water to remove the catalyst Adding an alkali compound to the reaction product obtained in the above step to perform a dehydrochlorination reaction , Step of Obtaining the Target Epoxy Resin The most distinctive feature of the present invention is that a decatalyst step by washing with water is included before the dehydrochlorination reaction step. The other steps are almost the same as the conventional two-stage method, but as will be described later, the addition of this step has a very large effect on improving yield and purity. It is not necessarily clear what mechanism of decatalyst brings about improvements in purity and yield, but it is likely that if a catalyst capable of ring-opening epoxy groups is present until the final stage of the epoxy resin manufacturing process, the resulting epoxy resin will be There is a possibility that the molecules may react with each other, resulting in a high molecular weight, or that side reactions such as the reaction between water and epichlorohydrin may be promoted. It seems that it will bring.

Next, the operations in each step will be described in detail.

First, the raw material polyphenol compound is added in an amount of 3 to 7 per equivalent of its phenolic hydroxyl group.
Dissolve in a molar excess of the epihalohydrin compound of general formula (A) and add the catalyst.

X: Cl・Br R: H or CH ₃ Catalysts used here include benzyltrimethylammonium chloride, tetramethylammonium chloride, tetramethylammonium bromide, triethylmethylammonium chloride, β-hydroxypropyltrimethylammonium chloride, benzyltrimethyl Examples include ammonium bromide. The amount of the catalyst used is 0.1 to 10 mol% based on the raw material polyhydric phenol compound. The reaction is carried out in substantially anhydrous conditions at a temperature of 20-180°C, preferably 50-120°C, for 2-40 hours.

Since the catalyst is easily soluble in water, only the catalyst can be easily removed by simply pouring water into the reaction solution.Moreover, since water and epichlorohydrin are immiscible, water can also be easily removed. Washing with water may be done once, but it is preferable to wash with water three times in order to obtain a sufficient effect.

In this step, the chlorohydrin ether obtained in step 1 is subjected to a dehydrochlorination reaction by adding 0.8 to 1.2 moles of an alkali compound per equivalent of the phenolic hydroxyl group of the phenolic compound as the raw material to obtain the desired epoxy resin. . As the alkali compound used here, potassium hydroxide, sodium hydroxide, sodium methylate, etc. are known, and any of them can be used.

[Effects of the Present Invention] According to the present invention, a polyfunctional epoxy resin having excellent heat resistance and water resistance can be obtained with high purity and high yield.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 500 with a stirring device, a thermometer, a dropping funnel, and a device to cool and liquefy the azeotropic vapor of epichlorohydrin and water and return only the epichlorohydrin layer to the reaction system.
24.3 g of phloroglucin (a phenolic compound represented by formula (B) that has three phenolic hydroxyl groups and two molecules of water of crystallization) in a ml four-necked flask.
(0.15mol), epichlorohydrin 177.2ml
(2.25 mol) was heated and stirred in an oil bath at 50°C to completely dissolve phloroglucin.

Once a homogeneous solution is obtained, reduce the pressure of the reaction thread to about 100 mmHg, azeotrope the water of crystallization and epichlorohydrin to remove water, then return to normal pressure and add 1.67 g of benzyltrimethylammonium chloride.
(0.009 mol) was added and stirred at 50°C for 24 hours. Thereafter, 200 ml of purified water was added, stirred vigorously for 10 minutes, left to stand, separated into two layers, and the water tank portion was removed by suction three times to remove the catalyst, benzyltrimethylammonium chloride. Then, the system was heated under reduced pressure again to azeotropically remove a small amount of water remaining in the system, and then 50 g of a 36% aqueous solution of sodium hydroxide was added dropwise over 3 hours. At this time, the reaction system was maintained at a temperature of 80°C and a reduced pressure of 100 mmHg, and water was continuously removed from the system by azeotropy. After the dropwise addition was completed, stirring was continued for 30 minutes, and then excess epichlorohydrin was removed by distillation.
Then, 100 ml of methyl isobutyl ketone and 100 ml of water were added, and the resulting salt was separated, washed repeatedly with water three times, the organic layer was taken out, and the solvent was removed using an evaporator to obtain phloroglucin triglycidyl ether. The final yield was 43 g, which was a high yield of 98% of the theoretical yield. The epoxy equivalent was measured by the hydrochloric acid-dioxane method and found to be 135, and the GPC analysis revealed that the content of dimers and higher oligomers was 10%.

Using the same equipment as in Comparative Example 1 and Example 1, the same amounts of phloroglucin and epichlorohydone were charged, and the same operations were carried out up to the step of removing crystallization water. Immediately, an aqueous sodium hydroxide solution was added dropwise to synthesize the one-step method. When this method was tried, a large amount of insoluble gel-like material was generated during the dropping process, making it impossible to produce the product.

Phloroglucin triglycidyl ether was obtained by carrying out exactly the same operation as in Comparative Example 2 and Example 1, except that the step of removing the catalyst by washing with water was not performed. The final yield was 38g, giving a yield of 86%. The epoxy equivalent was 152 as measured by the hydrochloric acid-dioxane method. Also, as a result of GPC analysis,
It was found that 18% of the oligomers were dimers or higher.

Claims (1)

[Scope of Claims] 1. A method for producing a polyfunctional epoxy resin, characterized by comprising at least the following steps. General formula (A) in the presence of a catalyst to polyhydric phenols
The step of adding an epihalohydrin compound as shown in X: Br or Cl R: H or CH ₃ Process of washing the reaction solution obtained in the above step with water to remove the catalyst Adding an alkali compound to the reaction product obtained in the above step to perform a dehydrochlorination reaction , the process of obtaining the desired epoxy resin