JPH0420008B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an epoxy resin that is particularly suitable for use in the electrical and electronic industries. In epoxy resins used as electrical and electronic materials, a low content of hydrolyzable chlorine is essential, and this is widely recognized in the industry. That is, hydrolyzable chlorine has adverse effects such as a decrease in electrical insulation and corrosion of lead wires.
In particular, in epoxy resins used as raw materials for encapsulating integrated circuits using semiconductors, it is essential that the content of hydrolyzable chlorine be low. For example, density 64
For integrated circuits larger than kilobits, the content of hydrolyzable chlorine is required to be less than 600 ppm. Various manufacturing methods have been proposed to reduce hydrolyzable chlorine. For example, the
No. 36000 describes a method for producing glycidyl ether of bisphenol A by gradually supplying an aqueous sodium hydroxide solution to a solution of bisphenol A and epichlorohydrin, in which water is azeotroped with epichlorohydrin under reduced pressure and low temperature conditions. A method is described in which the epichlorohydrin removed by distillation is recycled into the reaction system. In the examples of this patent, the hydrolyzable chlorine content is 1200 to 4500 ppm, and a sufficient improvement effect is not obtained. Japanese Patent Publication No. 54-90400,
JP-A-54-13596 and US Pat. No. 3,121,727 describe a method for producing glycidyl ether of polyhydric phenol, in which alcohol is added to a solution of polyhydric phenol and epihalohydrin. In the example of the patent, etc.,
-90400, the hydrolyzable chlorine of glycidyl ether of bisphenol A obtained from bisphenol A and epichlorohydrin is approximately 1000 ppm.
The total chlorine content is 1500 to 3500 ppm, and in the case of JP-A-13596, the hydrolyzable chlorine of the glycidyl ether of phenol novolac obtained from phenol novolac and epichlorohydrin is 1500 ppm, which is a sufficient improvement. No effect has been obtained. Further, although the patent and the like state that it is not necessary to remove water from the reaction system, it is known that epichlorohydrin decomposes even when it coexists with water, which is industrially disadvantageous. As a result of intensive research to obtain an epoxy resin with a low content of hydrolyzable chlorine, the present inventors discovered that this objective could be achieved by using a specific solvent during the epoxidation reaction, leading to the present invention. . That is, the present invention is an epoxy resin production method characterized by reacting monovalent or polyvalent phenols with epichlorohydrin in the presence of an alkali metal hydroxide and an aprotic polar solvent. The present invention has made it possible to produce an epoxy resin with a low content of hydrolyzable chlorine. The monovalent or polyvalent phenols used in the present invention are monovalent or polyvalent phenols consisting of phenol units substituted or unsubstituted with halogen, alkyl group, allyl group, alkenyl group, aryl group, or aralkyl group. Specifically, phenol, orthocresol, metacresol, para-cresol, diphenolmethane (bisphenol F), diphenolethane, diphenolpropane (bisphenol A), bisphenol tetrabromide A, 1,1 -Bis-(4-hydroxyphenyl)
-1-phenylethane, 1,1-bis(4-hydroxyphenyl)-1,1-dimethylmethane, phenol novolak, brominated phenol novolak, cresol novolak, brominated cresol novolak, resorcinol novolak, bromine Examples include, but are not limited to, resorcinol novolak, resorcinol, hydroquinone, methylresorcinol, bisphenol A tetrachloride, and the like. The alkali metal hydroxide used in the present invention is
Specific examples include sodium hydroxide, potassium hydroxide, etc., but are not limited to these.
The amount of the alkali metal hydroxide used is preferably about the same mole per mole of phenolic hydroxyl group. When the amount of alkali metal hydroxide used is small, the amount of gel produced as a by-product is small, which is advantageous in production, but hydrolyzable chlorine remains. If the amount of alkali metal hydroxide used is large, the amount of gel increases, which is disadvantageous in production. The aprotic polar solvent used in the present invention is
Specific examples include dimethyl sulfoxide, dimethyl sulfone, dimethyl formamide, dimethyl acetamide, tetramethyl urea, hexamethyl phosphoramide, etc., but are not limited to these. The amount of these aprotic polar solvents used is preferably 5 to 50 parts by weight per 100 parts by weight of epichlorohydrin. If the amount used is less than 5 parts by weight, the effects of the present invention will not be so significant. If the amount used is too large, intermolecular reactions will proceed, the epoxy equivalent (molecular weight per mole of epoxy group) will increase, and the quality of the glycidyl ether of phenols will deteriorate. Considering this, it is preferably 50 parts by weight or less. The amount of epichlorohydrin used in the present invention is preferably 2.5 mol to 20 mol, more preferably 4 mol to 20 mol, per 1 mol of phenolic hydroxyl group.
It is 10 moles. This means that if the amount of epichlorohydrin used is small, the quality of the epoxy resin will deteriorate due to the formation of high molecular weight products due to the intermolecular reaction, such as an increase in the melt viscosity of the epoxy resin, and furthermore, the amount of gel formed will increase, which is industrially disadvantageous. This is because, if the amount of epichlorohydrin used is large, the volume of the reaction mixture increases, resulting in industrial disadvantages such as decreased productivity. In the present invention, the epoxidation reaction of phenols can be carried out by a known method, except that an aprotic polar solvent is used as a solvent, and for example, it can be carried out as follows. First, monovalent or polyvalent phenols and epichlorohydrin are mixed in the proportions described above. Solid phenols are also dissolved in epichlorohydrin to form a homogeneous solution. Further, an aprotic polar solvent is added and mixed. While stirring and mixing, the alkali metal hydroxide is then added to carry out the reaction. In this reaction, the content liquid is azeotropically distilled under normal pressure or reduced pressure while maintaining the temperature at about 100 to 110°C under normal pressure and about 50 to 80°C under reduced pressure, depending on the pressure. Dehydration is performed by condensing the volatile components, separating the condensate from oil and water, and returning the oil to the reaction system. The alkali metal hydroxide is added in small portions or continuously over 2 to 7 hours in order to react uniformly. If it is added temporarily, the reaction will progress locally and a gel will form, which is not preferable.
After the reaction is completed, unreacted epichlorohydrin is first removed by distillation, then dissolved in a ketone such as methyl isobutyl ketone or an aromatic hydrocarbon solvent such as toluene, and insoluble alkali metal salts are separated. Further, the aprotic polar solvent is removed by washing with water, and the solvent is removed by distillation to obtain an epoxy resin. Glycidyl ethers of phenols are obtained. In the present invention, the epoxy equivalent means epoxy group 1
Defined by molecular weight per mole. In addition, hydrolyzable chlorine is produced by dissolving epoxy resin in dioxane.
The chlorine ions released when an alcoholic solution of potassium hydroxide was added and heated under reflux for 30 minutes were determined by back titration with a silver nitrate solution, and expressed as the weight percentage of chlorine atoms in the compound. less than,
The invention will be explained in more detail by way of examples, without restricting it thereto. Examples 1 to 5 and Comparative Examples 1 to 2 A thermometer, a dropping funnel for continuously adding an aqueous alkali metal hydroxide solution, a stirring blade, and water evaporating from the reaction system and epichlorohydrin are cooled and liquefied to form an organic layer and water. Using a separable flask with a baffle and a capacity of 1, which has a separating tube with a cooling tube that separates the layers based on their specific gravity differences, returns the organic layer to the reaction system, and removes the aqueous layer, the types and amounts of phenols shown in Table 1 are added. was reacted with epichlorohydrin. The reaction was carried out in the presence of an aprotic polar solvent of the type and amount shown in Table 1 while continuously adding an aqueous sodium hydroxide solution in the amount shown in Table 1 over a period of 5 hours. After the reaction is complete, unreacted epichlorohydrin is removed by vacuum distillation, and the resulting by-product salt and glycidyl ether of phenols containing an aprotic polar solvent are dissolved in methyl isobutyl ketone to separate the by-product salt and non-protic solvent. The protic polar solvent was removed by washing with water. Furthermore, methyl isobutyl ketone was removed by vacuum distillation to obtain an epoxy resin. Table 1 shows the amount of hydrolyzable chlorine and epoxy equivalent of the epoxy resin thus obtained. While the amount of hydrolyzable chlorine in Example 1 using an aprotic polar solvent was 330 ppm,
The amount of hydrolyzable chlorine in Comparative Example 1, which does not use an aprotic polar solvent, is 650 ppm.
The effect of reducing hydrolyzable chlorine by using an aprotic polar solvent is remarkable.

[Table] ☆☆ Number of moles of epichlorohydrin ☆☆☆ Number of moles of sodium hydroxide

Claims (1)

[Claims] 1. A method for producing an epoxy resin, which comprises reacting monovalent or polyvalent phenols with epichlorohydrin in the presence of an alkali metal hydroxide and an aprotic polar solvent.