JPH11171954A - Production of naphthol resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a naphthol resin having a controlled molecular weight distribution, excellent in a cost and useful for a raw material of an epoxy resin, etc., by reacting naphthols with formaldehyde, etc., under a basic condition in the presence of phenolics to generate a methylol substance and reacting the system under an acidic condition. SOLUTION: (B) Preferably, naphthols such as β-naphthol, etc., is reacted with (C) formaldehyde or a formaldehyde generating source substance under a basic condition and preferably, in the presence of (A) phenolics such as o- cresol at 10-35 deg.C for usually 5 min-5 hrs to generate a methylol substance, then the reaction system is made to an acidic condition and the system is reacted preferably at 30-130 deg.C for usually 10 min-5 hrs to obtain a resin useful as a hardener, etc., of an epoxy resin. A charging ratio of the components A to C is preferably 0.7-1.5 mol of the component A and 1.0-1.2 mol of the component C as formaldehyde to 1 mol of the component B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a naphthol resin having a specific structure.

[0002]

2. Description of the Related Art A naphthol resin is widely used in the field of electric and electronic parts as a raw material of an epoxy resin or a curing agent thereof due to its excellent properties such as heat resistance and moisture resistance which are characteristics of a resin having a naphthol skeleton. ing. And
In order to reduce the viscosity of these resins and improve the heat resistance of the cured product, it is considered effective to control the molecular weight distribution to be narrow. The following methods are known as methods for controlling the molecular weight distribution.

For example, a method of reacting phenols with formaldehyde in the presence of a basic catalyst, neutralizing the reaction, and then reacting with naphthols in the presence of an acidic catalyst,
It is described in JP-A-3-163128.

[0004]

However, in the above method, a large amount of expensive naphthols must be used, and the operation becomes complicated, such as an increase in the number of charging of raw materials, and the obtained naphthol resin is expensive. It becomes something. Therefore, a method for controlling the molecular weight distribution and producing a naphthol resin excellent in cost has been long-awaited.

[0005]

Means for Solving the Problems In view of such circumstances, the present inventors have intensively studied for a simple method for producing a naphthol resin having a controlled molecular weight distribution, and as a result, have completed the present invention.

That is, the present invention relates to (1) a method of reacting naphthols with formaldehyde or a formaldehyde-generating substance in the presence of phenols under basic conditions to form a methylol compound, and then reacting the reaction system under acidic conditions. After doing
A method for producing a naphthol resin, wherein (2) the method for producing a naphthol resin according to the above (1), wherein the naphthol is β-naphthol; -The method for producing a naphthol resin according to the above (1) or (2), which is cresol or a mixture thereof.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
Specific examples of naphthols that can be used in the present invention include α-naphthol and β-naphthol.
Among them, β-naphthol is an α having two reactive sites.
It is particularly preferable because the number of reaction active sites is as small as one compared with naphthol, and the production of a high molecular weight substance is suppressed, the molecular weight distribution is easy, and the raw material is inexpensive when producing the target naphthol resin.

Specific examples of phenols usable in the present invention include phenol, o-cresol, m-cresol, p-cresol, 2,5-di-tertbutylphenol, 2,6-dimethylphenol, 2,4-dimethylphenol and 2,4-dimethylphenol. Dimethylphenol, 2-tertbutylphenol, 2
-Tertbutyl-5-methylphenol, 2-ter
Substituted phenols having an alkyl group having 1 to 10 carbon atoms, such as t-butyl-4-methylphenol and p-octylphenol, substituted phenols having a halogen atom such as brominated phenol, substituted phenols having an allyl group such as 2-allylphenol And the like, among which phenol, o-cresol, m-cresol and p-cresol are preferred. These phenols can be used alone or in combination of two or more.

The formaldehyde-generating substance used in the present invention is a substance that forms formaldehyde in a methylolation reaction as described below, and examples thereof include paraformaldehyde, trioxane, tetraoxane and the like.

The charge ratio of naphthols, phenols, formaldehyde or a formaldehyde-generating substance is usually 0.1 mol per 1 mol of naphthols.
5 to 2.0 mol, preferably 0.7 to 1.5 mol, formaldehyde or formaldehyde-generating substance is usually 0.9 to 1.3 mol, preferably 1.0 to 1.2 mol, as formaldehyde.

The reaction can be carried out in the absence of a solvent or in the presence of a solvent. Specific examples of using a solvent include toluene, xylene, methyl isobutyl ketone,
Water and the like are mentioned, and these may be used alone or in combination of two or more. The amount of the solvent used is usually 30 to 300% by weight, preferably 50 to 2% by weight based on the total weight of the charged raw materials.
50% by weight.

The reaction is carried out under a basic condition by charging a predetermined amount of phenols, naphthols, formaldehyde or a formaldehyde generating substance and a basic catalyst. Under basic conditions, a starting methylol form is formed. The reaction temperature for methylolation is usually 5 to 40C, preferably 10 to 35C, and the reaction time is usually 5 minutes to 5 hours.

As the basic catalyst, an alkali metal hydroxide or an alkali metal carbonate is used. Specific examples include sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate and the like, with sodium hydroxide being preferred. The addition amount of the basic catalyst may be an amount sufficient for the methylolation reaction to proceed, and is usually 0.02 to 1.5 equivalents, preferably 0.05 to 1.2 equivalents, per 1 mol of naphthols. It is. The basic catalyst may be added as a solid or in the form of an aqueous solution, but is preferably an aqueous solution. When added as an aqueous solution, the concentration is usually 10 to 50% by weight,
Preferably it is 15 to 45% by weight.

After the completion of the methylolation reaction, a neutralization treatment is carried out using an acidic substance such as hydrochloric acid or sulfuric acid as a neutralizing agent, and p of the reaction system is reduced.
The H value is adjusted to 4 to 7, preferably 5 to 7. The salt generated by the neutralization treatment does not have to be removed by washing with water, but when washing with water, it may be carried out according to a conventional method. For example, water is added to the reaction mixture, and the separation and extraction operation is repeated.

Next, the resulting methylol compound is further reacted under acidic conditions by adding an acidic catalyst. As the acidic catalyst, various catalysts can be used, and preferred are inorganic or organic acids such as hydrochloric acid, sulfuric acid, p-toluenesulfonic acid, and oxalic acid, and boron trifluoride, anhydrous aluminum chloride, and Lewis acids such as zinc chloride. Hydrochloric acid, sulfuric acid and p-toluenesulfonic acid are preferred. The use amount of these acid catalysts is not particularly limited, but is usually 0.05 to 50 parts by weight, preferably 0.1 to 100 parts by weight for the raw material naphthols.
-20 parts by weight.

The temperature for carrying out the above reaction is usually 5 to 18
0 ° C., preferably 30 to 130 ° C., and the reaction time is usually 10
Minutes to 5 hours. After the completion of the condensation reaction, it is preferable to further add the above-mentioned acid catalyst if necessary, raise the temperature of the reaction system to 60 to 130 ° C., and carry out the reaction. The reaction time in this case is usually 0.5 to 30 hours, preferably 1 to 25 hours. In addition, it is preferable to remove water generated during the condensation reaction out of the reaction system by using a fractionating tube in order to quickly perform the reaction.

After completion of the reaction, the pH value of the product is adjusted to 3 to 7, preferably 5 to 7 by performing a neutralization treatment or a water washing treatment. Sodium hydroxide for water washing,
Alkali metal hydroxides such as potassium hydroxide, ammonia, diethylenetriamine, triethylenetriamine,
The treatment may be performed using various basic substances such as aniline and organic amines such as phenylenediamine as a neutralizing agent. In the case of a water washing treatment, it may be carried out according to a conventional method. For example, water in which the neutralizing agent is dissolved is added to the reaction mixture, and the liquid separation extraction operation is repeated.

After neutralization or washing with water, the solvent and unreacted substances are distilled off under reduced pressure and the product is concentrated to obtain a naphthol resin having a controlled molecular weight distribution.

[0019]

Next, the present invention will be described in more detail with reference to examples. In the following, parts are by weight unless otherwise specified.

Example 1 A round-bottom flask equipped with a stirrer, a condenser and a thermometer was charged with 288 parts of β-naphthol and 841 parts of methyl isobutyl ketone (hereinafter MIBK), and dissolved by stirring. , O-cresol 1
08 parts were added. Add paraformaldehyde (9
(2%) 67 parts was added and reacted at 25 ° C. for 2 hours.
After completion of the reaction, about 41 parts of 35% hydrochloric acid was added for neutralization. Then, 5.7 parts of p-toluenesulfonic acid was added and the mixture was added at 25 ° C for 2 hours.
The reaction was carried out at 80 ° C. for 2 hours. Thereafter, water washing was performed until the reaction solution became neutral, and MIBK in the oil layer was distilled off under heating and reduced pressure to obtain 416 parts of a target naphthol resin.
The yield was 99%. 15 of the obtained naphthol resin
ICI melt viscosity at 0 ° C is 7.6P, softening point is 10
At 5 ° C, the hydroxyl equivalent was 140 g / eq.

Example 2 The procedure of Example 1 was repeated except that 108 parts of p-cresol was used instead of o-cresol, and the reaction was carried out in the same manner. 415 parts of the desired naphthol resin was obtained, and the yield was 99%. The obtained naphthol resin had an ICI melt viscosity at 150 ° C. of 8.0 P, a softening point of 109 ° C., and a hydroxyl equivalent of 140 g / eq.

[0022]

According to the present invention, a naphthol resin having a controlled molecular weight distribution can be easily produced, and its industrial value is great. In addition, the naphthol resin obtained by such a production method has low viscosity in addition to excellent physical properties such as heat resistance and moisture resistance, which are characteristics of the resin having a naphthol skeleton. It is suitable as a curing agent and can be used widely in the fields of electric and electronic parts.

Claims (3)

[Claims] (1) In the presence of a phenol, a naphthol is reacted with formaldehyde or a formaldehyde-generating substance under a basic condition to form a methylol compound, and then the reaction is carried out under an acidic condition. A method for producing a naphthol resin. 2. The method for producing a naphthol resin according to claim 1, wherein the naphthol is β-naphthol. 3. The method for producing a naphthol resin according to claim 1, wherein the phenol is o-cresol, p-cresol or a mixture thereof.