JPH1192543A - Aromatic hydrocarbon/formaldehyde resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a low viscosity and highly reactive aromatic hydrocarbon/ formaldehyde resin by condensing an aromatic hydrocarbon with formaldehyde and a specified aliphatic alcohol in the presence of an acidic catalyst under specified conditions. SOLUTION: 1 mol of an aromatic hydrocarbon, 1-5 mol of formaldehyde and 0.5-2 mol of a 1-8C aliphatic alcohol are condensed with each other at a reaction temperature of 40-80 deg.C under conditions in which the formaldehyde concentration in a component comprising the formaldehyde, water, the 1-8C aliphatic alcohol and sulfuric acid which are the starting materials is at least 20 wt.%, and the sulfuric acid concentration is 30-50 wt.%. Thus, a lowly viscous polyfunctional aromatic hydrocarbon/formaldehyde resin having a viscosity of 100-50,000 cP (25 deg.C),desirably 300-30,000 cP (25 deg.C) and containing 1.8-3.0, desirably 1.9-2.5 formed substituents on the average per aromatic ring in the resin can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic hydrocarbon formaldehyde resin, particularly a polyfunctional resin containing a large amount of active groups highly reactive with a third component and having low viscosity. It relates to a hydrocarbon formaldehyde resin.

[0002]

2. Description of the Related Art It is known to produce an aromatic hydrocarbon formaldehyde resin by reacting an aromatic hydrocarbon with formaldehyde under an acidic catalyst. Particularly, a resin obtained by reacting meta-xylene with formaldehyde under a sulfuric acid catalyst is known. It is well known as xylene formaldehyde resin.
This xylene formaldehyde resin is modified with a third component (phenols, carboxylic acids, glycols, etc.) and used as a thermosetting resin material for various applications, or used as a tackifier such as an adhesive or an adhesive. It is also known to be used as a diluent for an epoxy resin or a plasticizer for a vinyl chloride resin.

When used as the above-mentioned thermosetting resin material, the aromatic hydrocarbon formaldehyde resin contains a dimethylene ether bond or an acetal bond that reacts with the third component, or an oxygen such as a methylol group or an alkoxymethyl group at the molecular terminal. Since there are many contained groups and the reactivity with the third component must be excellent, and the cured product obtained from the modified resin obtained by the reaction with the third component has excellent physical properties, It is necessary to reduce the content of a component having a methylene bond which does not react with the component as a main bonding group, that is, a diallylmethane component.

[0004] Further, in order to have excellent reactivity with the third component, and to obtain excellent physical properties of the cured product obtained from the modified resin obtained by the reaction with the third component, it is necessary that the aromatic ring formed by the reaction with the formaldehyde be used. Is H-NM
1.8 to 3.0, preferably 1.
It needs to be 9 to 2.5. In the present invention,
The average number of substituents per aromatic ring in the resin was measured using the above-described H-NMR, and the resin as a reaction product was converted to a methyl proton of about 1.8 to 2.6 ppm and 6.9.
It was determined from the integrated value of the proton directly connected to the aromatic ring at around ppm.

In order to make the average of the number of substituents per aromatic ring in an aromatic hydrocarbon formaldehyde resin close to 2, a method described in Japanese Patent Application Laid-Open No. 61-228013 discloses a method in which formaldehyde and an aromatic hydrocarbon are combined with each other. The molar ratio is 1: 2.0 to 5.0, the sulfuric acid concentration in the component consisting of formaldehyde, water and sulfuric acid is 15 to 35% by weight, the reaction temperature is 80 to 110 ° C, the oil phase (resin phase) and water There is a method in which the average of the number of substituents per aromatic ring is set to around 2 by setting the stirring speed low enough to observe the phase interface.

The resin obtained by this method has an average number of substituents per aromatic ring of about 2, but the obtained resin has a very high viscosity of not less than 200,000 centipoise (25 ° C.). Has a problem that it needs to be handled at a high temperature. In addition, in the synthesis of this resin, the reaction is stopped at a low reaction rate, so that the resin yield is undesirably reduced to about 60% with respect to the charged aromatic hydrocarbon.

In order to lower the viscosity of the aromatic hydrocarbon formaldehyde resin, the molar ratio of formaldehyde to aromatic hydrocarbon is 1: 0.5 to 5.0, and the formaldehyde and aliphatic alcohol having 1 to 8 carbon atoms are used. To 1:
There is also a method in which the reaction temperature is 0.2 to 1 and the reaction temperature is 85 to 96 ° C.

The resin obtained by this method has a viscosity of 20 to 1
Although it has a low viscosity of 5,000 centipoise (25 ° C.), the average number of substituents per aromatic ring of the obtained aromatic hydrocarbon formaldehyde resin is about 1.6, and diallyl methane which does not react with the third component Component content of 10
Since it is as high as ~ 15% by weight, the reactivity with the third component is inferior, so that it is not preferable.

[0009]

DISCLOSURE OF THE INVENTION The present invention is directed to an aromatic hydrocarbon formaldehyde resin which does not have the above-mentioned drawbacks found in conventional aromatic hydrocarbon formaldehyde resins, has low viscosity and is highly reactive. It is intended to provide a manufacturing method.

[0010]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that when a condensation reaction between an aromatic hydrocarbon and formaldehyde is carried out, a reaction temperature of 40 to 40 is used in the presence of an aliphatic alcohol having 1 to 8 carbon atoms and an acidic catalyst. The inventors have found that the above problem can be solved by performing a condensation reaction at -80 ° C, and have completed the present invention.

That is, the present invention relates to an aromatic hydrocarbon formaldehyde resin obtained by subjecting an aromatic hydrocarbon, formaldehyde and an aliphatic alcohol having 1 to 8 carbon atoms to a condensation reaction at a reaction temperature of 40 to 80 ° C. in the presence of an acidic catalyst. Having a viscosity of 100 to 50,000 centipoise (25 ° C.)
And a low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin having an average number of formed substituents per aromatic ring in the resin of 1.8 to 3.0, and a sulfuric acid catalyst for converting the aromatic hydrocarbon and formaldehyde To a condensation reaction in the presence of
When obtaining an aromatic hydrocarbon formaldehyde resin, formaldehyde is used in an amount of 1 to 5 moles per mole of aromatic hydrocarbon, and an aliphatic alcohol having 1 to 8 carbon atoms in 0.5 to 1 mole per mole of aromatic hydrocarbon. 2 mol is present, and the formaldehyde concentration in the component consisting of formaldehyde, water, aliphatic alcohol having 1 to 8 carbon atoms, and sulfuric acid in the raw material component is 20% by weight or more, and the concentration of sulfuric acid is 30 to 50% by weight. And a method for producing a low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin, wherein the condensation reaction is carried out at a reaction temperature of 40 to 80 ° C.

The aromatic hydrocarbons used in the present invention include toluene, ethylbenzene, xylene (including three isomers), mesitylene, pseudocumene, monocyclic aromatic hydrocarbon compounds having 10 or more carbon atoms, naphthalene,
Examples thereof include polycyclic aromatic hydrocarbon compounds such as methylnaphthalene. In addition, these mixtures can also be used.

Examples of the formaldehyde include compounds that generate formaldehyde, such as formalin, paraformaldehyde, and trioxane, which are industrially easily available. In the present invention, paraformaldehyde,
Even when a polymer such as trioxane is used, the amount of the polymer is specified based on one molecule of formaldehyde.

The alcohol used in the present invention acts as a terminal terminator for the aromatic hydrocarbon formaldehyde resin, and therefore may be any aliphatic alcohol, and practically, an aliphatic alcohol having 1 to 8 carbon atoms can be used. Carbon number 1
Four aliphatic alcohols are particularly desirable. As aliphatic alcohols having 1 to 8 carbon atoms, methanol, ethanol,
n-propanol, iso-propanol, n-butanol, sec-butanol, tert-butanol, pentanol (including each isomer), heptanol (including each isomer), 2-ethyl-hexyl alcohol, n-octanol, etc. Can be exemplified.

The catalyst used for the condensation reaction includes sulfuric acid, paratoluenesulfonic acid and the like, but sulfuric acid is generally suitable. The amount of the catalyst used is, for example, when sulfuric acid is used, the concentration in a component consisting of formaldehyde, water, an aliphatic alcohol having 1 to 8 carbon atoms, and sulfuric acid is 30 to 30%.
It is desirable to adjust so as to be 50% by weight. When the sulfuric acid concentration is the above concentration, an appropriate reaction rate can be obtained, and further, it is possible to prevent the resin viscosity from increasing due to the high reaction rate.

In the condensation reaction, the molar ratio of the starting aromatic hydrocarbon to formaldehyde is preferably from 1: 1 to 5,
It is particularly preferably in the range of 1: 1.5 to 3. When the molar ratio is within the above range, the resin yield of the aromatic hydrocarbon formaldehyde resin obtained by the reaction can be kept relatively high, and the amount of unreacted remaining formaldehyde can be reduced.

Also, formaldehyde, water,
The formaldehyde concentration in the component consisting of an aliphatic alcohol having 1 to 8 carbon atoms and sulfuric acid is preferably 20% by weight or more. At a formaldehyde concentration of 20% by weight or more, a practically desirable reaction rate can be obtained.

The molar ratio of the aromatic hydrocarbon to the alcohol used in the condensation reaction is preferably from 1: 0.5 to 2, and particularly preferably from 0.7 to 1.2. When the molar ratio is within the above range, a resin having the desired viscosity of the present invention is obtained.

The reaction temperature in the present invention is usually from 40 to 80.
° C. When the reaction temperature exceeds 80 ° C., a resin having the specific physical properties which is the object of the present invention cannot be obtained.
If the reaction temperature is lower than 40 ° C., the reaction rate becomes slow, which causes practical problems.

The reaction time is preferably about 4 to 8 hours. With the above reaction time, a resin having the desired physical properties of the present invention can be obtained economically.

The stirring speed is preferably such that the interface between the water phase and the oil phase (resin phase) is observed. The stirring speed varies depending on the size of the reactor, the shape of the stirrer, and the like, so it is difficult to determine the stirring speed unconditionally. For example, a laboratory scale reactor (with an internal volume of about 2 to 5 liters) is used, When the stirrer is used, the rotation speed is approximately 100 to 200 rpm. Specifically, a stirring speed for suppressing the condensation reaction time to about 4 to 8 hours and suppressing the reaction rate of the raw material aromatic hydrocarbons to a range of 60 to 90 wt% is appropriately selected. By adding an aliphatic alcohol such as methanol to a system in which an aromatic hydrocarbon and formaldehyde are heated and reacted in the presence of a sulfuric acid catalyst under the above reaction conditions to synthesize a resin, the added alcohol becomes xylene and mesitylene formaldehyde resin. It is incorporated as an alkoxy group at the terminal of the molecule to lower the molecular weight and lower the viscosity, and the average number of substituents per aromatic ring in the resin can be made 1.8 to 3.0.

The viscosity of the aromatic hydrocarbon formaldehyde resin obtained in the present invention is 100 to 50,000 centipoise (25 ° C.), preferably 300 to 30,000 centipoise (25 ° C.). The viscosity of the aromatic hydrocarbon formaldehyde resin is 100 to 50,000 by appropriately adjusting the mixing ratio of the aromatic hydrocarbon to be used, formaldehyde, and the aliphatic alcohol having 1 to 8 carbon atoms, sulfuric acid concentration, reaction temperature, and stirring speed. The viscosity can be controlled at centipoise (25 ° C.) and the viscosity is 100 centipoise (2
If it is less than 5 ° C.), the loss on heating increases, and if it exceeds 50,000 centipoise (25 ° C.), handling becomes difficult, which is not preferable.

The average number of substituents per aromatic ring in the obtained aromatic hydrocarbon formaldehyde resin is 1.8 to 3.
0, preferably 1.9 to 2.5. The average number of substituents per aromatic ring in the aromatic hydrocarbon formaldehyde resin is determined by adjusting the blending ratio of the aromatic hydrocarbon to be used, formaldehyde, and the aliphatic alcohol having 1 to 8 carbon atoms, sulfuric acid concentration, reaction temperature, and stirring speed. By adjusting appropriately, 1.
It can be set to 8-3.0. If the average number of substituents per aromatic ring of the resin is less than 1.8, the number of active groups having high reactivity with the third component decreases, which is not preferable.

According to the above-mentioned method, the resin of the present invention is obtained in high yield, and the obtained resin has low viscosity and is polyfunctional, so that it can be used with phenols, carboxylic acids, glycols and the like having active hydrogen. Has high reactivity.

[0025]

EXAMPLES Examples and comparative examples are shown below to explain the present invention in detail. In Examples and Comparative Examples, “%” was used.
Indicates "% by weight" unless otherwise specified. The reactor used in the following Examples and Comparative Examples is a separable flask having an internal volume of 2 liters (round bottom cylindrical shape, flask inner diameter of 130 mm) equipped with a thermometer, a reflux condenser, and a stirrer. To measure the average number of substituents per aromatic ring in the aromatic hydrocarbon formaldehyde resin obtained by the reaction, H-
NMR was used. The resin, which is a reaction product, is 1.8 to 2.
When the number of methyl protons in meta-xylene near 6 is 6 (9 in the case of mesitylene), the integral value of the proton directly connected to the aromatic ring at about 6.9 ppm is calculated, and the calculated value is used as the proton directly connected to meta-xylene. The value subtracted from the number 4 (3 in the case of mesitylene) was taken as the number of intra-ring hydrogen reactions. The drop times of meta-xylene and mesitylene in Examples and Comparative Examples were all 40 minutes.

Example 1 A separable flask was charged with 577 g of 50% formalin, 115 g of methanol and 384 g of 98% sulfuric acid, the temperature of the reaction system was set to 75 ° C., the stirring speed was set to 167 rpm, and 517 g of meta-xylene was added to the aqueous layer over 40 minutes. It was dropped. After the completion of the addition of meta-xylene, the reaction was further continued for 5 hours and 20 minutes. After the completion of the reaction, the mixture was allowed to stand to separate a resin phase (oil phase) and an aqueous phase, and then the resin phase was washed three times with water and 20 to 30 mmHg / 120.
Unreacted meta-xylene was distilled off under reduced pressure at 130 ° C. for 1 hour to obtain 584 g of a xylene formaldehyde resin having a viscosity of 13,000 centipoise (25 ° C.). Table 1 shows the reaction yield, the charging of the raw materials, and the physical properties of the resin obtained by the reaction.

Examples 2 to 4 Reactions were carried out in the same manner as in Example 1 under the reaction conditions shown in Table 1. Table 1 shows the reaction yield and physical properties of the resin obtained by the reaction.

Comparative Example 1 A reaction was carried out in the same manner as in Example 1. However, the methanol / meta-xylene molar ratio was 0.3, the charge of 98% sulfuric acid was 241 g (sulfuric acid concentration in the aqueous phase: 25 wt%), the reaction temperature was reflux temperature (93 ° C.), and the stirring speed was 232 rpm. Table 1 shows the reaction yield and the physical properties of the resin obtained by the reaction.

Comparative Example 2 A reaction was carried out in the same manner as in Example 1. However, the molar ratio of methanol / meta-xylene was 0.7, 270 g of 98% sulfuric acid was charged (sulfuric acid concentration in the aqueous phase: 25 wt%), the reaction temperature was reflux temperature (93 ° C.), and the stirring speed was 600 r.
pm. Table 1 shows the mixing ratio of the raw materials charged and the physical properties of the resin obtained by the reaction.

Example 5 A reaction was carried out in the same manner as in Example 1. However, 40%
598 g of formalin, 115 g of methanol and 331 g of 98% sulfuric acid were charged, and the amount of mesitylene dropped was 499 g.
The formaldehyde / mesitylene molar ratio was 2.4,
The methanol / mesitylene molar ratio was 1.1, the formaldehyde concentration in the aqueous phase was 28 wt%, and the sulfuric acid concentration in the aqueous phase was 31 wt%. The reaction was performed at a reaction temperature of 75 ° C. and a stirring speed of 190 rpm, and the reaction was carried out for 5 hours and 20 minutes after completion of the dropwise addition. Table 2 shows the mixing ratio of the raw materials charged and the physical properties of the resin obtained by the reaction.

Example 6 A method was performed in the same manner as in Example 1. However, 86%
227 g of paraformaldehyde, 226 g of iso-propanol, and 320 g of 98% sulfuric acid were charged, and the amount of mesitylene dropped was 454 g. The formaldehyde / mesitylene molar ratio was 2, the iso-propanol / mesitylene molar ratio was 1, and the formaldehyde concentration in the aqueous phase was 26w.
t%, and the sulfuric acid concentration in the aqueous phase was 35 wt%. The reaction was performed at a reaction temperature of 70 ° C. and a stirring speed of 190 rpm. After the completion of the dropwise addition of mesitylene, the reaction was carried out for 5 hours and 20 minutes. Table 2 shows the mixing ratio of the raw materials charged and the physical properties of the resin obtained by the reaction.

Example 7 A reaction was carried out in the same manner as in Example 1. However, 86%
243 g of paraformaldehyde, n-octanol 42
6 g and 350 g of 98% sulfuric acid were charged, and the amount of mesitylene dropped was 371 g. The molar ratio of formaldehyde / mesitylene was 2.6, the molar ratio of n-octanol / mesitylene was 1, and the concentration of formaldehyde in the aqueous phase was 21 wt.
%, And the sulfuric acid concentration in the aqueous phase was 30 wt%. The reaction was carried out at a reaction temperature of 70 ° C. with a stirring speed of 167 rpm, and the reaction was carried out for 5 hours and 20 minutes after the completion of the dropwise addition of mesitylene. Table 2 shows the mixing ratio of the raw materials charged and the physical properties of the resin obtained by the reaction.

[0033]

The aromatic hydrocarbon formaldehyde resin obtained by the present invention is a polyfunctional resin containing a large amount of active groups having low viscosity and high reactivity with the third component. The aromatic hydrocarbon formaldehyde resin can be produced in high yield.

[0034]

[Table 1] Example / Comparative Example No. 1 real 2 real 3 real 4 ratio 1 ratio 2 charge (g) 50% formalin 577 597 579 599 693 720 methanol 115 117 115 86-69 98% sulfuric acid 384 315 384 381 241 270 Dropping amount of meta-xylene (g) 517 528 517 529 384 626 Charge molar ratio HCHO ^{* 1} / MX ^{* 2} 2.0 2.0 2.0 2.0 2.0 2.0 MeOH ^{* 3} / MX ^{* 2} 1.0 1.0 1.0 0.8 0.3 0.7 Water phase ^{* 4} HCHO concentration ( 27 29 27 28 37 34 Aqueous phase ^{* 4} Sulfuric acid concentration (wt%) 35 30 35 35 25 25 Reaction temperature (℃) 75 75 70 70 93 93 Stirring speed (rpm) 167 167 167 172 172 232 600 Reaction time ^{* 5} (hours) 5.3 5.3 5.3 5.3 5.3 3.3 Reaction rate ^{* 6} (wt%) 87.6 67.5 65.3 63.1 55.1 100 Resin yield ^{* 7} (wt%) 113 74 73 72 60 117 Viscosity (cp / 25 ° C) 13000 310 3700 28000 > 100000 1200 average substitution of 2.0 1.8 2.1 2.3 2.0 1.6 (Note) * 1: formaldehyde * 2: meta-xylene * 3: methanol * 4: formaldehyde, Phase * 5 consisting of aliphatic alcohols, and sulfuric acid: meta-xylene After completion of the dropwise addition of the reaction time * 6: Reaction rate of starting material aromatic hydrocarbon * 7: Yield of resin obtained to the dropped-xylene

[0035]

Table 2 Example No. 5 5 6 7 (g) 40% formalin 598--86% HCHO-227 243 Methanol 115--iso-propanol-226-n-octanol--426 Pure water 301 78 89 98% sulfuric acid 331 320 350 Mesitylene dripping amount (g) 499 454 371 Charge molar ratio HCHO ^{* 1} / Mes ^{* 2} 2.4 2.0 2.6 ROH ^{* 3} / Mes ^{* 2} 1.1 1.0 1.0 Water phase ^{* 5} HCHO concentration (wt%) 28 26 21 Aqueous phase ^{* 5} Sulfuric acid concentration (wt%) 31 35 30 Reaction temperature (° C) 75 70 70 Stirring speed (rpm) 190 190 167 Reaction time ^{* 4} (h) 5.3 5.3 5.3 Reaction rate ^{* 6} (wt%) 88 72 65 Resin yield ^{* 7} (wt%) 101 77 73 Viscosity (cp / 25 ° C) 5400 9200 3700 Average number of substituents 2.1 1.8 2.1 (Note) * 1: Formaldehyde * 2: Mesitylene * 3: Alcohol used * 4: Mesitylene Reaction time after completion of dropping * 5: Formaldehyde, water, aliphatic alcohol * 6: Reaction rate of raw material aromatic hydrocarbon * 7: Yield of resin obtained based on mesitylene dropped

Claims (10)

[Claims] 1. An aromatic hydrocarbon formaldehyde resin obtained by subjecting an aromatic hydrocarbon, formaldehyde, and an aliphatic alcohol having 1 to 8 carbon atoms to a condensation reaction in the presence of an acidic catalyst at a reaction temperature of 40 to 80 ° C. , Viscosity is 100
50,000 centipoise (25 ° C.), and the average number of formed substituents per aromatic ring in the resin is 1.8 to
A low viscosity polyfunctional aromatic hydrocarbon formaldehyde resin having a 3.0. 2. The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to claim 1, wherein the aromatic hydrocarbon used is at least one of xylene and mesitylene. 3. The acidic catalyst used is sulfuric acid, and the sulfuric acid concentration in a component consisting of formaldehyde, water, an aliphatic alcohol having 1 to 8 carbon atoms and sulfuric acid in the raw material component is 30.
The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to claim 1, wherein the amount is from 50 to 50% by weight. 4. A compounding ratio (molar ratio) of an aromatic hydrocarbon and formaldehyde to be used is 1: 1 to 5, and formaldehyde, water, an aliphatic alcohol having 1 to 8 carbon atoms, and sulfuric acid in a raw material component. The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to any one of claims 1 to 3, wherein the concentration of formaldehyde in the component comprising is 20% by weight or more. 5. An aromatic hydrocarbon to be used and having 1 to 8 carbon atoms.
The mixing ratio (molar ratio) of the aliphatic alcohol is 1: 0.5
The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to any one of claims 1 to 4, which has a molecular weight of from 2.0 to 2.0. 6. The alcohol used is at least one selected from aliphatic alcohols having 1 to 4 carbon atoms.
6. The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to any one of claims 1 to 5. 7. The low-viscosity polyfunctional aromatic carbon according to claim 1, wherein the average number of substituents formed per aromatic ring in the resin obtained by the condensation reaction is 1.9 to 2.5. Hydrogen formaldehyde resin. 8. The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to claim 1, which has a viscosity of 300 to 30,000 centipoise (25 ° C.). 9. A condensation reaction of an aromatic hydrocarbon and formaldehyde in the presence of a sulfuric acid catalyst to obtain an aromatic hydrocarbon formaldehyde resin, wherein formaldehyde is used in an amount of 1 to 5 mol per mol of the aromatic hydrocarbon. And an aliphatic alcohol having 1 to 8 carbon atoms is present in an amount of 0.5 to 2 mol per 1 mol of the aromatic hydrocarbon, from formaldehyde, water, an aliphatic alcohol having 1 to 8 carbon atoms, and sulfuric acid in the raw material components. Low-viscosity polyfunctional aromatic hydrocarbon characterized in that the formaldehyde concentration in the component is 20% by weight or more, the sulfuric acid concentration is 30 to 50% by weight, and the condensation reaction is carried out at a reaction temperature of 40 to 80C. A method for producing a formaldehyde resin. 10. Formaldehyde before the start of the reaction is 1.5 to 3 moles per 1 mole of the aromatic hydrocarbon and has 1 to 1 carbon atoms.
The aliphatic alcohol of 8 is added in an amount of 0.7 to 1.2 moles per mole of the aromatic hydrocarbon to be dropped, and the reaction time is 4 to 8 moles.
The low-viscosity polyfunctional aromatic hydrocarbon formaldehyde resin according to claim 9, wherein the condensation reaction is carried out at such a low stirring speed that the interface between the oil phase (resin phase) and the aqueous phase can be maintained. Production method.