JP2001089546A - Production of phenol-aldehyde resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a high quality phenol-aldehyde resin which is useful as a raw material for epoxy resins and so on. SOLUTION: This method for producing the phenol-aldehyde resin comprises subjecting a phenol compound and an aldehyde compound to a condensation reaction in the presence of an acid catalyst in a solvent. Therein, the content of carboxylic acids in the aldehyde compound is <=0.4%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a phenol-aldehyde resin by subjecting a phenol and an aldehyde to a condensation reaction, and an epoxide by reacting the phenol-aldehyde resin obtained by the method with an epihalohydrin. The present invention relates to a method for producing a resin.

[0002]

2. Description of the Related Art Heretofore, as a method for producing a phenol-aldehyde resin, there has been known a method of subjecting raw materials phenols and aldehydes to a dehydration condensation reaction in an appropriate solvent in the presence of an acid catalyst [for example, "Phenolic resin" (A
ndre Knop, Plastic Age Co.)]. Phenol-aldehyde resins are used for molding materials, adhesives, paints,
It is used as a material for electronic components and the like, and as a raw material for resins such as epoxy resins, cyanate resins and ion exchange resins, and various quality and physical properties are required according to its use. However, when a conventional method for producing a phenol-aldehyde resin is used, the obtained phenol-aldehyde resin is not always satisfactory in terms of quality. For example, it was used as a raw material for an epoxy resin, particularly an epoxy resin for electronic parts. In this case, the quality of the obtained epoxy resin, such as the content of hydrolyzable chlorine, was not always sufficient.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a method for producing a high-quality phenol-aldehyde resin useful as a raw material for an epoxy resin.

[0004]

The aldehyde used as one of the raw materials for the phenol-aldehyde resin is usually
In the production process, carboxylic acids are generated by a side reaction, and a small amount of carboxylic acids is present in the finally obtained aldehyde. In addition, since aldehydes are easily oxidized to carboxylic acids by an oxidizing agent such as oxygen, a small amount of carboxylic acid is gradually generated in the aldehyde during storage. As a result of intensive studies by the present inventors, they have found that the above objects can be achieved by reducing the content of carboxylic acids in the aldehyde used to a specific amount or less, and completed the present invention. That is, the present invention relates to (I).
A method for producing a phenol-aldehyde resin by subjecting a phenol and an aldehyde to a condensation reaction in a solvent in the presence of an acid catalyst, wherein the content of the carboxylic acid in the aldehyde is 0.4% or less. The present invention relates to a method for producing a characteristic phenol-aldehyde resin. Further, the present invention provides (II). The present invention relates to a method for producing an epoxy resin, comprising reacting a phenol-aldehyde resin obtained by the production method described in the above (I) with an epihalohydrin in the presence of an alkali metal hydroxide.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a method for producing a phenol-aldehyde resin of the present invention will be described. As the phenols used in the present invention, monovalent or divalent or higher phenols can be used. For example, phenol, cresol, xylenol, ethylphenol, butylphenol, t-butyl-methylphenol, phenylphenol, chlorophenol, Bromophenol, resorcin, catechol, hydroquinone, and the like can be mentioned, and if necessary, two or more of them can be used.

The aldehydes used in the present invention include:
Divalent or divalent or higher aldehydes can be used,
For example, formaldehyde, trioxane, paraformaldehyde, acetaldehyde, acrolein, benzaldehyde, hydroxybenzaldehyde, vanillin,
Examples thereof include isovanillin and glyoxal, and two or more of them can be used as necessary. The amount of the aldehyde used is usually 0.01 to
It is 2 molar equivalents, preferably 0.1-1 molar equivalent.

The phenol-aldehyde resin suitably produced by the method of the present invention includes the following general formula (1)

[0008]

Embedded image [In the formula (1), R ¹ and R ² are each independently a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or 1 carbon atom.
Represents an alkoxy group of 6 to 6, i and j each independently represent a number of 0 to 2, and n represents a number of 1 to 20. A phenol-aldehyde resin represented by the following general formula (2):

[0009]

Embedded image [In the formula (2), the definitions of R ¹ and i are the same as the definitions in the formula (1). And aldehydes represented by the following general formula (3)

[0010]

Embedded image [In the formula (3), the definitions of R ² and j are the same as the definitions in the formula (1). Can be produced by using an aldehyde represented by the formula: The phenol aldehyde resin is preferable from the viewpoint of heat resistance of a cured product of a thermosetting resin such as an epoxy resin.

R ¹ and R ^{2 in the} general formulas (1) to (3) include, for example, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom in the case of a halogen atom. In the case of a hydrocarbon group, a methyl group, an ethyl group, a propyl group,
Butyl group, pentyl group, hexyl group, and other linear or branched alkyl groups, such as cyclohexyl group, phenyl group,
In the case of an alkoxy group having 1 to 6 carbon atoms, a linear or branched alkoxy group such as a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group, a hexoxy group and the like can be mentioned.

The aldehyde used in the present invention has a carboxylic acid content of 0.4% or less, preferably 0.2% or less.
% Or less. Here, the carboxylic acid means a carboxylic acid in which the formyl group of the aldehyde is a carboxyl group. For example, when the aldehyde is 4-hydroxybenzaldehyde, the carboxylic acid means 4-hydroxybenzoic acid. I do. When the content of the carboxylic acid in the aldehyde exceeds 0.4%, the quality of the obtained phenol-aldehyde resin is reduced. For example, when the phenol-aldehyde resin is used as a raw material of the epoxy resin, This causes an increase in the content of hydrolyzable chlorine in the resin.

The method of reducing the content of carboxylic acids in the aldehyde to 0.4% or less depends on the type of the aldehyde used and the type of the carboxylic acid contained therein. Examples of the method include washing the solution dissolved in the solvent with water or alkaline water, distillation, crystallization, and the like.

The content of carboxylic acids in aldehydes can be determined by liquid chromatography (LC), gas chromatography (GC), ion chromatography (I
C), and the like. Specific measurement conditions vary depending on the types of aldehydes and carboxylic acids to be measured. For example, the conditions shown in the examples may be appropriately selected according to the types.

As the solvent used in the reaction of the present invention, water, an organic solvent, or a mixed solvent of water and an organic solvent, if necessary, is used. Examples of the organic solvent include hydrocarbon solvents such as toluene and xylene; halogenated hydrocarbon solvents such as chloroform and methylene chloride; ether solvents such as dioxane, diethyl ether and ethylene glycol dimethyl ether; propylene glycol monomethyl Alkoxy alcohol solvents such as ethers; ketone solvents such as methyl ethyl ketone and methyl isobutyl ketone; and the like, and if necessary, two or more thereof. The amount of the solvent used is usually 10 to 2000 parts by weight, preferably 100 to 1000 parts by weight, based on 100 parts by weight of the total of phenols and aldehydes.
Parts by weight.

As the acid catalyst used in the present invention, known acid catalysts for synthesizing phenol-aldehyde resins can be used, for example, mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid, etc .; oxalic acid, toluenesulfonic acid, And the like. The amount of the acid catalyst used is usually 0.001 to 1 molar equivalent, preferably 0.001 to 0.
One molar equivalent.

In the reaction of the present invention, the order of adding the phenols, aldehydes, solvent and acid catalyst is as follows.
For example, after all the raw materials are charged in advance, the reaction temperature may be set to a predetermined value.Alternatively, after charging phenols, a solvent and an acid catalyst, aldehydes may be added at a predetermined reaction temperature, After charging the solvent and the acid catalyst, phenols may be added at a predetermined reaction temperature.

[0018] The reaction temperature is usually in the range of 20 to 300 ° C, preferably 50 to 200 ° C. The reaction time is usually 1
-20 hours, preferably 2-10 hours.

As a post-treatment method of the reaction of the present invention, for example, the catalyst may be removed by washing with water as required, and then the phenol-aldehyde resin may be removed by concentration. In such a case, it may be taken out by a method such as crystallization.

Examples of the use of the phenol-aldehyde resin obtained by the production method of the present invention include, for example, molding materials,
Materials such as adhesives, paints, electronic parts, epoxy resin,
Resin raw materials such as a cyanate resin and an ion exchange resin are exemplified. For example, when used as a raw material of an epoxy resin, particularly an epoxy resin for an electronic component, an epoxy resin having excellent quality such as a hydrolyzable chlorine content can be obtained, which is preferable.

Next, a method for producing the epoxy resin of the present invention will be described. The epihalohydrins used in the present invention include, for example, epichlorohydrin, epibromohydrin, and the like. If necessary, two or more of them can be used. Among them, epichlorohydrin is preferred from the viewpoint of reactivity. The amount of the epihalohydrin used is usually 3 to 15 molar equivalents, preferably 5 to 10 mol equivalents to the phenolic hydroxyl group of the phenol-aldehyde resin.
It is a molar equivalent.

In the reaction of the present invention, a solvent may be used from the viewpoint of handleability. Examples of the solvent include aprotic polar solvents such as dimethyl sulfoxide, dimethylformamide, and 1,3-dimethyl-2-imidazolidine; alkoxy alcohols such as dipropylene glycol monomethyl ether and methyl cellosolve; diethyl ether and dioxane And the like; and the like, and if necessary, two or more kinds thereof can also be used.
The amount of the solvent to be used is generally 10 to 300 parts by weight, preferably 20 to 10 parts by weight, per 100 parts by weight of the epihalohydrin.
0 parts by weight.

Examples of the alkali metal hydroxide used in the present invention include lithium hydroxide, sodium hydroxide, potassium hydroxide and the like. If necessary, two or more of them can be used. Among them, from the viewpoint of industrial availability,
Sodium hydroxide is preferred. The alkali metal hydroxide is usually used as a solid or a 5 to 50% by weight aqueous solution.
Aqueous solutions of up to 50% by weight are preferred. The amount of the alkali metal hydroxide to be used is usually 0.8 to 1.3 molar equivalents, preferably 0.1 to 1.3 molar equivalents, based on the hydroxyl groups of the phenol-aldehyde resin.
9 to 1.1 molar equivalents.

In the reaction of the present invention, the order of addition of the phenol-aldehyde resin, epihalohydrin, alkali metal hydroxide and, if necessary, solvent may be, for example, a mixture of phenol-aldehyde resin, epihalohydrin and solvent. The alkali metal hydroxide may be added continuously or intermittently, or the alkali metal hydroxide and the phenol-aldehyde resin may be separately or mixed while the epihalohydrins and the solvent are mixed. And may be added continuously or intermittently.

The reaction temperature is usually in the range of 10 to 80 ° C, preferably 30 to 60 ° C. As the reaction time, for example, when an alkali metal hydroxide is added to a mixture of a phenol-aldehyde resin, an epihalohydrin and a solvent, the addition time is usually 0.5 to 20 hours, preferably 2 to 8 hours. It is. The reaction pressure is preferably set such that the reaction solution boils according to the composition and temperature of the reaction solution. Further, it is preferable to carry out the reaction while distilling and removing water in the system together with epihalohydrins.

As a post-treatment method of the reaction solution, for example, the following known methods can be adopted. That is, the reaction solution is concentrated, and all or part of the epihalohydrin and the solvent are distilled off to obtain a concentrated solution containing an epoxy resin and a by-product alkali salt. The concentration is usually performed under reduced pressure at a temperature of 160 ° C. or less. The concentration time is desirably short in order to prevent the epihalohydrins and the epoxy resin from deteriorating. The distillate containing epihalohydrins can be purified by distillation or the like, if necessary, and reused.

The concentrate thus obtained is usually added to
Organic solvents such as methyl isobutyl ketone, toluene and xylene are added and mixed to dissolve the epoxy resin, filtered,
An epoxy resin solution is obtained by, for example, removing by-product alkali salts, residual solvent, and the like by washing with water, and then removing the solvent from the solution by distillation or the like to obtain an epoxy resin.

Further, a solid or aqueous solution of an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide or the like is added to the above-mentioned epoxy resin solution, and the mixture is treated usually at 50 to 90 ° C. for 1 to 3 hours. May be. The amount of the alkali metal hydroxide used is usually 0.001 to 0.001 to the phenolic hydroxyl group of the phenol-aldehyde resin used in the reaction.
0.2 molar equivalent. By performing this treatment, the hydrolyzable chlorine content of the obtained epoxy resin can be further reduced.

The above-mentioned treatment solution is usually filtered, if necessary,
After removing by-product alkali salts, residual solvent, and the like by washing with water, excess alkali metal hydroxide is neutralized with phosphoric acid, carbon dioxide gas, or the like. If the alkali salt further generated during the neutralization is removed by filtration, washing with water or the like, and the solvent is removed from the resulting epoxy resin solution by distillation or the like, the epoxy resin can be obtained.

[0030]

The present invention will be described in more detail with reference to the following Examples.
It is not specified. The LC measurement conditions were as follows:
It is on the street. LC measurement conditions  Aldehyde (4-hydroxybenzaldehyde) 50m
g, and dissolve in 10 ml of acetonitrile to dissolve the sample.
A liquid was measured under the following conditions. The resulting chromatogram
Carboxylic acid (4-hydroxybenzoate)
(Perfume acid) was determined. Apparatus: Hitachi L-7000 series Column: Wakosil-II 3C18HG (3 μm, 4.6 mm φ × 15 cm) Column temperature: 40 ° C. Mobile phase: Liquid A Water Water B 0.1% acetic acid / acetonitrile Gradient method: Liquid B = 10% → (20 minutes) → 50% → (10 minutes) → 100% (hold 10 minutes) Flow rate: 1.0 ml / min Detection wavelength: UV 254 nm Sample solution injection volume: 3 μl

Example 1 (Synthesis of phenol-aldehyde resin) 1 L4 equipped with a stirrer, thermometer, separation tube and cooler
In a one-necked flask, 234.0 g of 2-t-butyl-5-methylphenol, 4-hydroxybenzaldehyde 91 having a content of 4-hydroxybenzoic acid determined by LC measurement of 0.05% or less (lower than the detection limit). 0.6 g, p-
0.93 g of toluenesulfonic acid and toluene 22
7.9 g was added, and water by-produced by the reaction was distilled off with toluene at a temperature in the range of 112 to 114 ° C., and the reaction was carried out for 5 hours while returning the organic layer of the distillate to the reaction system. After the completion of the reaction, the reaction solution was cooled to 80 ° C., neutralized by adding 1.95 g of a 10% aqueous sodium hydroxide solution, and 78.0 g of dipropylene glycol monomethyl ether (DPM) was added thereto, followed by 0.5 hour at 80 ° C. Stir to dissolve the phenol-aldehyde resin. After the temperature of the solution was raised to 140 ° C. at normal pressure, the solution was concentrated at 140 ° C. under reduced pressure to 100 Torr, and toluene was distilled off. The concentrated solution was cooled to 80 ° C., diluted with 390.1 g of DPM, and 758.2 g of a 40% strength phenol-aldehyde resin DPM solution.
I got

Example 2 (Synthesis of Epoxy Resin) In a 1 L separable flask equipped with a stirrer, a thermometer, a dropping funnel, a separation tube and a cooler, the 40 obtained in Example 1 was placed.
% Phenol-aldehyde resin DPM solution 35
0.0 g, epichlorohydrin 647.5 g, and D
After adding 113.8 g of PM and replacing with nitrogen, 85 Torr,
The temperature was adjusted to 60 ° C., and 78.7 g of a 48.3% aqueous sodium hydroxide solution was added dropwise thereto over 6 hours. During this time, water was distilled off together with epichlorohydrin, and the reaction was carried out while returning the organic layer of the distillate into the reaction system. After completion of the reaction, the reaction mixture was concentrated under reduced pressure to remove epichlorohydrin and DPM, and 457 g of methyl isobutyl ketone was added to the residue, and the mixture was washed with water to remove by-product sodium chloride.
The resulting solution of the epoxy resin in methyl isobutyl ketone was concentrated under reduced pressure, and methyl isobutyl ketone was distilled off to obtain 172.4 g of an epoxy resin as a residue. Table 1 shows the evaluation results of the obtained epoxy resins.

Comparative Example 1 (Synthesis of phenol-aldehyde resin) In Example 1, the content of 4-hydroxybenzoic acid determined by LC measurement was 0.05% or less (below the detection limit).
Instead of 4-hydroxybenzaldehyde,
C. A 40% phenol-aldehyde resin DPM solution was prepared in the same manner as in Example 1 except that 4-hydroxybenzaldehyde having a 4-hydroxybenzoic acid content of 0.5% determined by C measurement was used. 753.5 g were obtained.

Comparative Example 2 (Synthesis of Epoxy Resin) In Example 2, Comparative Example 1 was used in place of the 40% phenol-aldehyde resin DPM solution obtained in Example 1.
40% phenol-aldehyde resin DPM obtained in
Except that the solution was used, the same procedure as in Example 2 was carried out to obtain 169.8 g of an epoxy resin. Table 1 shows the evaluation results of the obtained epoxy resins.

[0035]

[Table 1] Epoxy equivalent: Dissolve epoxy resin (0.4 g) in dioxane (25 mL), add N / 5 hydrochloric acid / dioxane solution (25 mL) to react with epoxy group, and then add excess hydrochloric acid to N / 10 hydroxylation. The epoxy equivalent was determined by titration with a sodium-methanol solution. -Softening point: According to JIS K7234 (1986)
It was measured by the ring and ball method. -ICI viscosity: Measured at 150 ° C and 50 Hz using a cone and plate viscometer manufactured by ICI. Hydrolysable chlorine content: Epoxy resin (1 g) is dissolved in dioxane (30 mL), 1N potassium hydroxide in ethanol (5 mL) is added, and chlorine ions released when heated at reflux for 30 minutes are converted to N. / 100 Titration with a silver nitrate solution, expressed as the weight percentage of chlorine atoms in the compound.

[0036]

According to the method of the present invention, a high-quality phenol-aldehyde resin can be obtained, and the obtained phenol-aldehyde resin is useful as a raw material for an epoxy resin.

Claims (3)

[Claims] 1. A method for producing a phenol-aldehyde resin by subjecting a phenol and an aldehyde to a condensation reaction in a solvent in the presence of an acid catalyst, wherein the carboxylic acid content in the aldehyde is 0.4%. A method for producing a phenol-aldehyde resin, comprising: 2. A phenol-aldehyde resin having the following general formula (1): ## STR1 ## [In the formula (1), R ¹ and R ² are each independently a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or 1 carbon atom.
Represents an alkoxy group of 6 to 6, i and j each independently represent a number of 0 to 2, and n represents a number of 1 to 20. The method according to claim 1, wherein the phenol-aldehyde resin is represented by the formula: 3. A method for producing an epoxy resin, comprising reacting a phenol-aldehyde resin obtained by the method according to claim 1 with epihalohydrins in the presence of an alkali metal hydroxide.