JPH02113011A - Production of novolak resin - Google Patents

Abstract

PURPOSE:To obtain the subject resin without requiring dehydrating and boiling steps for a long period and containing any residual unreacted monomer by mixing phenols with an aqueous solution of an alkaline metal hydroxide, mixing and reacting the resultant mixture with aldehydes and further reacting the mixture at the boiling temperature. CONSTITUTION:The objective resin obtained by mixing phenols with an aqueous solution of an alkaline metal hydroxide (preferably sodium hydroxide) in an amount of 0.9-1.1mol based on 1 equiv. phenolic hydroxyl group, then mixing and reacting aldehydes (e.g., formaldehyde) in an amount of 0.7-1.0mol based on 1equiv. phenolic hydroxyl group at <50 deg.C and further reacting the mixture at the boiling temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing novolak resin. More specifically, the present invention relates to a method for producing a novolak resin that can eliminate the need for a long dehydration and boiling step in the reaction of phenols and aldehydes, thereby shortening the reaction time for novolac formation.

(Prior art) Novolak resin has 1. It is widely used in various resin molding materials, including epoxy and novolac resins as molding materials for encapsulating electronic components.

This novolac resin is usually produced by subjecting phenols and aldehydes to an addition condensation reaction in the presence of an acid catalyst. Regarding this addition condensation reaction between phenols and aldehydes, since unreacted monomers, water, catalysts, etc. remain in the reaction system after the reaction, not only post-treatments such as neutralization, filtration, and drying are required. , a step is required to remove unreacted monomers and the like. For this reason, a dehydration boiling process such as vacuum distillation or steam distillation has conventionally been essential, separate from post-treatments such as neutralization.

(Problems to be Solved by the Invention) However, in such conventional novolak resin manufacturing methods, in order to completely remove unreacted monomers and completely decompose the catalyst in the dehydration and boiling process, it is usually necessary to raise the temperature Processing at a temperature of about 160°C or higher for 6 hours or more is required. Therefore, the production efficiency of novolac resin products is considerably low due to the presence of this dehydration and boiling process.

This invention was made in view of the above circumstances, and eliminates the drawbacks of the conventional method that requires a long dehydration and boiling process. The purpose of the present invention is to provide a method for producing novolac resin with excellent reaction efficiency.

(Means for Solving the Problems) In order to solve the above problems, the present invention mixes phenols with an aqueous solution of an alkali metal hydroxide in an amount of 0.9 to 1.1 moles per equivalent of phenolic hydroxyl group. and then 0.7 to 1.0 mol of aldehyde per equivalent of phenolic hydroxyl group is mixed and reacted at a temperature of less than 50°C, and further reacted at a boiling temperature. do.

The production method of the present invention, when adding and condensing phenols and aldehydes, allows the addition reaction and the condensation reaction to proceed in two stages under specific conditions, and reduces unreacted monomers remaining after the reaction. This eliminates the need for dehydration and boiling treatment.

As the phenols used in this invention, known phenols that have been conventionally used in the production of novolac resins can be used. Examples include phenol, cresol, xylenol, butylphenol, nonylphenol, bromophenol, and hydroquinone.

Such phenols are mixed with an aqueous solution of an alkali metal hydroxide without using the acid catalyst used in the conventional method. As the alkali metal hydroxide, sodium hydroxide, potassium hydroxide, barium hydroxide, etc. can be used, but it is particularly preferable to use sodium hydroxide.

The alkali metal hydroxide is used in an amount of 0.9 to 1.1 mol per equivalent of the phenolic hydroxyl group of the above-mentioned phenols.

If it is less than 0.9 mol, unreacted monomers remaining after the reaction cannot be sufficiently reduced.

Moreover, if it exceeds 1.1 mol, it is not preferable because neutralization in the post-process is troublesome and raw materials are lost.

Next, aldehydes are mixed into the mixture of phenols and alkali metal water/oxide. As the aldehyde to be used, conventional formaldehyde, paraformaldehyde, acetaldehyde, etc. can be used. The amount used is 0.7 to 1.0 mol per equivalent of the phenolic hydroxyl group of the above-mentioned phenols. If it is less than 0.7 mol, unreacted monomers of phenols will remain after the reaction, which is undesirable. On the other hand, if it exceeds 1.0 mol, gelation may occur during the reaction if the phenol is a trifunctional phenol compound. Furthermore, when the phenol is a trifunctional phenol compound, unreacted aldehydes remain after the reaction, which is not preferable.

The aldehydes are mixed at 50° C. in a cool room. This makes it possible to suppress the condensation reaction and allow the addition reaction to proceed preferentially, thereby reducing unreacted monomers in the novolac resin. When aldehydes are mixed at a temperature of 50° C. or higher, the boiling temperature of water in the reaction system, it is not possible to completely eliminate unreacted monomers after the reaction.

In order to mix aldehydes at a temperature of 50° C., it is preferable to add the aldehydes intermittently or intermittently while observing the temperature of the reaction system from time to time. Although this mixing depends on the concentration of the aldehydes used, it is usually desirable to carry out the mixing within one hour.

After the aldehydes are mixed with the phenols, that is, after the addition reaction is completed, the condensation reaction is allowed to proceed at a boiling temperature at which water in the reaction system evaporates. This makes it possible to produce a novolak varnish containing almost no unreacted monomers.

Finally, a novolac resin can be obtained by neutralizing the novolak varnish with a dilute acid, passing the suspension, and drying it by a conventional method.

(Function) In this invention, aldehydes are mixed with a mixture of phenols and alkali metal hydroxides in a specific proportion at a temperature of less than 50°C, and the addition reaction of aldehydes to phenols is allowed to proceed. Next, by allowing the condensation reaction to proceed at the boiling temperature of the addition reaction product, novolak resin containing almost no unreacted monomers can be produced with high efficiency without the need for the conventional long dehydration and boiling process. You can get it at

(Example) In a 500 cc four-eye flask equipped with a thermometer, stirrer, dropping funnel, and reflux condenser, 0-cresol
Prepare 8 parts (1 mol).

100 parts (1 mol) of a 40% NaOH aqueous solution was added dropwise over 30 minutes while being careful not to generate heat.

Next, 65 parts (0.8 mol) of a 37% formalin aqueous solution was added dropwise into the solution over 30 minutes so that the reaction temperature was 45° C., and the mixture was mixed and reacted.

After the formalin aqueous solution was added dropwise, the temperature was raised and the reaction was carried out at reflux temperature for 5 hours to obtain a festival.

This resin was neutralized with dilute hydrochloric acid, filtered, and the residue was washed twice with purified water and dried at 80°C in a vacuum dryer to obtain a novolac resin.

Post-processing from neutralization to obtaining dried resin required 2 hours. Therefore, the time required to produce the novolac resin was 30 minutes for dropping the NaOH aqueous solution, 30 minutes for dropping the formalin aqueous solution and allowing the reaction to occur, and 5 minutes for the reaction at reflux temperature.
The total time was 8 hours, including 2 hours of post-treatment.

When the obtained resin was analyzed by 13C-NMR, no carbon signal of methylol group (-CH20H) appeared, and it was confirmed that the obtained resin was not a resol resin but a novolak resin. Further, when this resin was analyzed by gas chromatography (GCP), it was found that the residual amount of unreacted cresol monomer was 0.3%.

Table 1 shows these results. A novolac resin with a small amount of residual monomer was obtained in a short time without performing the conventional dehydration and boiling process.

The resulting Novolac V! 117 parts of J fat and epoxy resin (
ESCN-205, manufactured by Sumitomo Chemical) 205 parts and 2E4
By blending 3 parts of H7 (manufactured by Shikoku Kasei) and heating at a temperature of 170°C for 5 hours, a high-quality cured resin product could not be obtained.T was 190°C.

(Comparative Example 1) 0-Cresol 10 was placed in a four-eye flask similar to the example.
8 parts (1 mol) and 65 parts (0,
8 mol) and 0.9 part of oxalic acid as a catalyst were added and reacted at reflux temperature for 7 hours.

Next, this reaction product was dehydrated for 2 hours at normal pressure, and further dehydrated for 2 hours at a vacuum degree of 500 Torr.
The mixture was raised to ℃ and boiled for 2 hours to thermally decompose the oxalic acid to obtain a novolac resin. The total time for the dehydration and boiling process was 6 hours, and the total time required to produce the resin was 13 hours.

The remaining amount of unreacted cresol monomer in the obtained resin was analyzed in the same manner as in the example, and as shown in Table 1, it was found to be 0.
．． It was 2%.

(Comparative Example 2) A resin was produced in the same manner as in Example except that 49 parts (0.6 mol) of a 37% formalin aqueous solution was used, and the residual amount of unreacted cresol monomer was analyzed. As expected, unreacted cresol was 8.4%.

(Comparative Example 3) A resin was produced in the same manner as in Example except that 70 parts (0.7 mol) of 40% NaOH aqueous solution was used, and the residual amount of unreacted talesol monomer was analyzed.

3.2% remained.

(Comparative Example 4) A resin was produced in the same manner as in Example except that a 37% formalin aqueous solution was added dropwise over 30 minutes so that the temperature of the reaction system was 70°C.
The remaining amount of unreacted cresol monomer was analyzed.

The residual amount was 2.7%.

The above results are summarized in Table 1.6 (Effects of the invention) This invention significantly shortens the production time without requiring the long dehydration and boiling process that was conventionally required after the reaction. , it becomes possible to produce a novolak resin in which almost no unreacted monomer remains.

Claims (2)

[Claims] (1) Mix phenols with an aqueous solution of alkali metal hydroxide in an amount of 0.9 to 1.1 mol per equivalent of phenolic hydroxyl group, and then 0.7 to 1.1 mole per equivalent of phenolic hydroxyl group.
A method for producing a novolac resin, which comprises mixing and reacting 1.0 mol of aldehydes at a temperature of less than 50°C, and further reacting at a boiling temperature. (2) The method for producing a novolak resin according to claim (1), wherein the aldehydes are mixed and reacted within one hour.