JP2005089662A - Method for manufacturing resol type phenolic resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a resol type phenolic resin with a reduced content of unreacted phenols and aldehydes in a high yield. <P>SOLUTION: The method of manufacturing the resol type phenolic resin comprises a step (a) of reacting a phenol with an aldehyde with the use of an aqueous solution of a phosphoric acid containing ≥0.2 moles of the phosphoric acid per mole of the phenol to synthesize a novolak type phenolic resin and a step (b) of reacting the above novolak type phenolic resin with an aldehyde with the use of an alkaline catalyst to synthesize a resol type phenolic resin. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a resol type phenol resin.

Resole-type phenolic resins are usually charged in a molar ratio of 1 to 3 moles of phenols with 1 to 3 moles of aldehydes, sodium hydroxide, aqueous ammonia, tertiary amines, oxides or hydroxides of alkaline earth metals It can be obtained by reacting with an alkaline catalyst such as sodium carbonate.
However, when the reaction is carried out using these catalysts, unreacted phenols and aldehydes remain after the completion of the reaction. When there is much content of unreacted phenols, when using a resol type phenol resin, a bad odor will generate | occur | produce and a working environment will be worsened. Furthermore, when it hardens | cures, the problem that the mechanical strength of hardened | cured material falls arises. Moreover, when there is much content of unreacted aldehydes, this will also generate a strange odor and is unpreferable on environmental health.

  Therefore, the resol type phenol resin is required to have a low content of unreacted phenols and aldehydes. As a method of reducing the content of unreacted phenols and aldehydes, a method of removing unreacted phenols by reacting aldehydes at a low molar ratio of 1.3 mol or less with respect to 1 mol of phenols; There is a method of removing unreacted aldehydes by reacting aldehydes with 1 mol of phenols at a high molar ratio of 1.7 mol or more.

  As a method for removing unreacted phenols, a steam distillation method is generally known. However, the steam distillation method has a disadvantage that it is less effective unless it is performed for a long time, and the removal process takes a long time. Unreacted aldehydes can be removed by adding a catching agent for aldehydes such as urea, but by adding a large amount of a catching agent for aldehydes, this acts as a denaturing agent, resulting in a cured product. There was a problem that the physical properties such as water resistance deteriorated.

  In addition to this, for example, after adding water so that the phenol resin concentration is about 5 to 45% by weight, the tube length (L) and the tube inner diameter (D) are preheated to about 100 to 130 ° C. ) And a ratio (L / D) of at least 1000, it is sent in a reduced pressure state, and at this time, a large amount of water vapor is generated continuously while suppressing excessive formation or adhesion of the condensation polymerization product to the inner surface of the tube wall. There is a method of performing dehydration treatment. By such an operation, unreacted phenols and aldehydes can be distilled off together with the dehydrating liquid (see, for example, Patent Document 1). However, this method has a problem that the process becomes remarkably complicated and a special apparatus for the water washing process is required.

In addition to this, there is a method of synthesizing a novolak type phenol resin and then converting it to a resole resin as in the reaction procedure of the present invention. In the case of this method, it is necessary to synthesize a novolak type phenol resin having a low content of unreacted monomers and a high content of low molecular weight components.
However, when a reaction is carried out using a small amount of normal inorganic acid or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, phosphorous acid, oxalic acid, and p-toluenesulfonic acid, such a novolak type phenol resin is efficiently synthesized. There was a problem that it was difficult to do.

For example, there is a method in which a reaction molar ratio of aldehydes to phenols is reacted at a low molar ratio of 0.3 or less to synthesize a novolak type phenol resin having a large amount of low molecular weight components, and then converting this to a resole resin. However, when the reaction is performed at such a low molar ratio, a step of removing a large amount of unreacted phenols by a technique such as vacuum distillation after synthesizing a novolak type phenol resin is required.
On the other hand, if the reaction is carried out at a high reaction molar ratio of aldehydes to phenols, the unreacted phenols contained in the novolak type phenol resin can be reduced, but the molecular weight of the resulting novolak type phenol resin tends to increase. When this is converted to a resole resin, there is a problem that it is easily gelled.

  In addition, a method is disclosed in which phenols and aldehydes are reacted with an organic phosphonic acid to synthesize a novolac-type phenol resin, which is converted into a resole resin (see, for example, Patent Document 2).

Japanese Patent Publication No. 58-17211. JP 2002-206015 A

The present invention provides a method for producing a resol-type phenol resin with a low content of unreacted phenols and aldehydes in a high yield.

Such an object is achieved by the following present inventions (1) to (10).
(1) A method for producing a resol type phenolic resin,
(A) a step of reacting phenols and aldehydes with a phosphoric acid aqueous solution containing 0.2 mol or more of phosphoric acid with respect to 1 mol of the phenols to synthesize a novolak type phenol resin,
(B) a step of synthesizing a resol type phenolic resin by reacting the novolac type phenolic resin with an aldehyde using an alkaline catalyst;
A process for producing a resol-type phenolic resin, comprising:
(2) In the step (a), the reaction molar ratio (F ₁ / P) between the phenols (P) and the aldehydes (F ₁ ) is 0.3 to 0.95, as described in (1) above Of producing a resol type phenolic resin.
(3) The method for producing a resol-type phenol resin according to (1) or (2), wherein the water content in the reaction system is 1 to 40% by weight in the step (a).
(4) The method for producing a resol type phenol resin according to any one of (1) to (3), wherein the reaction is performed at a reaction temperature of 40 to 150 ° C. in the step (a).
(5) The method for producing a resol type phenol resin according to any one of (1) to (4), wherein the phosphoric acid is phosphoric acid.
(6) The method for producing a resol type phenol resin according to any one of (1) to (5), wherein the concentration of the phosphoric acid in the aqueous phosphoric acid solution is 20 to 99% by weight.
(7) After the step (a), the reaction system is washed with water, and the concentration of the phosphoric acids contained in the novolac phenol resin is adjusted to 3% by weight or less. ) A method for producing a resol type phenolic resin according to any one of the above.
(8) The method for producing a resol type phenol resin according to any one of the above (1) to (7), wherein unreacted phenols contained in the novolac type phenol resin are 3% by weight or less.
(9) The method for producing a resol type phenol resin according to any one of the above (1) to (8), wherein the degree of dispersion of the molecular weight distribution of the novolak type phenol resin is 1.2 to 3.0.
(10) The method for producing a resol type phenol resin according to any one of the above (1) to (9), wherein unreacted phenols contained in the resol type phenol resin are 3% by weight or less.

  In the present invention, a novolac phenol resin is synthesized by reacting a phenol and an aldehyde with an aqueous phosphoric acid solution containing a predetermined amount of phosphoric acid, and reacting the novolac phenol resin with the aldehyde. It is a manufacturing method of a resol type phenol resin which has a process, and a resol type phenol resin with few contents of unreacted phenols and aldehydes can be manufactured in high yield.

Below, the manufacturing method (henceforth only a "manufacturing method") of the resol type phenol resin of this invention is demonstrated in detail.
In the production method of the present invention, first,
(A) A novolac type phenol resin is synthesized by reacting phenols and aldehydes with an aqueous phosphoric acid solution containing 0.2 mol or more of phosphoric acid with respect to 1 mol of the phenols.

  In the production method of the present invention, the phenols used in the step (a) are not particularly limited. For example, cresols such as phenol, o-cresol, m-cresol, and p-cresol, 2,3-xylenol, 2 , 4-xylenol, 2,5-xylenol, 2,6-xylenol, 3,4-xylenol, xylenol such as 3,5-xylenol, ethylphenol such as o-ethylphenol, m-ethylphenol, p-ethylphenol , Butylphenol such as isopropylphenol, butylphenol, p-tert-butylphenol, alkylphenols such as p-tert-amylphenol, p-octylphenol, p-nonylphenol, p-cumylphenol, fluorophenol, chlorophenol, bromine Halogenated phenols such as phenol and iodophenol, monovalent phenol substitutes such as p-phenylphenol, aminophenol, nitrophenol, dinitrophenol and trinitrophenol, and monovalent phenols such as 1-naphthol and 2-naphthol And polyphenols such as resorcin, alkylresorcin, pyrogallol, catechol, alkylcatechol, hydroquinone, alkylhydroquinone, phloroglucin, bisphenol A, bisphenol F, bisphenol S, and dihydroxynaphthalene. These can be used alone or in combination of two or more.

Similarly, although not particularly limited as aldehydes, for example, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butyraldehyde, caproaldehyde, Examples include allyl aldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, and salicylaldehyde. These can be used alone or in combination of two or more.
These aldehydes can be used not only in the step (a) but also in the step (b) described later.

  The step (a) is characterized in that these phenols and aldehydes are reacted using an aqueous phosphoric acid solution.

  Here, as the phosphoric acid, a phosphoric acid compound that can be dissolved in water to form a phosphoric acid aqueous solution can be used, and is not particularly limited. For example, phosphoric acid (orthophosphoric acid), diphosphoric acid, triphosphoric acid, etc. In addition to linear polyphosphoric acid, cyclic polyphosphoric acid, diphosphorus pentoxide, phosphorous acid, hypophosphorous acid and the like, various phosphoric acid ester compounds can be mentioned. These can be used alone or in combination of two or more.

  Of these phosphoric acids, phosphoric acid is preferred. Phosphoric acid can be easily adjusted in concentration and can be obtained at low cost.

  Although it does not specifically limit as a density | concentration of phosphoric acid in this phosphoric acid aqueous solution, It is preferable that it is 20 to 99 weight%, More preferably, it is 40 to 99 weight%. By setting the concentration of phosphoric acid in the phosphoric acid aqueous solution to the above lower limit or more, the reaction between phenols and aldehydes can be efficiently advanced.

The amount of phosphoric acid used in the step (a) is 0.2 mol or more per 1 mol of phenols. Thereby, in the system which reacts phenols and aldehydes using phosphoric acid aqueous solution, distribution with the organic phase which has phenols as a main component, and the aqueous phase which consists of phosphoric acid aqueous solution can be stabilized.
The amount of the phosphoric acid is more preferably 0.3 to 1.0 mol, and particularly preferably 0.4 to 0.9 mol, with respect to 1 mol of phenols. Thereby, a novolak-type phenol resin having a narrow molecular weight distribution and a low content of unreacted phenols can be efficiently obtained.

  Increasing the amount of phosphoric acid tends to increase the effect of obtaining a high yield of novolak-type phenolic resin with a low content of unreacted phenols and a narrow molecular weight distribution. On the other hand, use of an amount exceeding 1.0 mol may not be economical because this effect is substantially unchanged. On the other hand, if the amount is less than 0.2 mol, the phosphoric acid concentration in the aqueous phase is too low to stably distribute the organic phase and the aqueous phase, so that the reaction rate decreases.

  In the step of synthesizing the novolac type phenol resin of the present invention, the water content in the reaction system when the phenols and aldehydes are reacted using an aqueous phosphoric acid solution is not particularly limited, but is 1 to 40% by weight. It is preferable that More preferably, it is 1 to 30% by weight.

  Here, the water content in the reaction system is the total amount of water present in the reaction system with respect to the total amount of phenols, aldehydes, phosphoric acid aqueous solution, novolac type phenol resin, etc. present in the reaction system. Refers to weight ratio. The water present in the reaction system includes water derived from the raw material to be added, such as water in an aqueous solution of phosphoric acid, water contained in aldehydes, and condensed water generated during the reaction.

  The water content in the reaction system can be calculated by taking the sum of the amount of water in the charged raw material and the amount of condensed water produced by the reaction as the amount of water in the reaction system and dividing this by the total amount charged. Also, when the reaction is carried out by distilling off water, the water content in the reaction system is reduced by subtracting the amount of water distilled off from the total amount of water content in the raw material and the amount of condensed water produced by the reaction. Can be calculated.

By carrying out the reaction with the water content preferably within the above range, a novolak-type phenol resin having a small content of unreacted phenols and a narrow molecular weight distribution can be obtained in a high yield.
By setting the water content in the reaction system to the above lower limit value or more, it is possible to prevent the phosphoric acids from becoming highly viscous or solidified. Moreover, since the fall of reaction rate can be suppressed by setting it as the said upper limit or less, reaction of phenols and aldehydes can be advanced efficiently.

In the step (a), the reaction molar ratio (F ₁ / P) between the phenols (P) and the aldehydes (F ₁ ) is not particularly limited, but is preferably 0.3 to 0.95. . More preferably, it is 0.4-0.9, Most preferably, it is 0.6-0.9 mol.
This reaction molar ratio can be appropriately selected and used according to the molecular weight of the target novolak-type phenol resin, but by setting the molar ratio to the above lower limit or more, the novolak content of unreacted phenols is small. Type phenolic resin can be obtained efficiently. Moreover, by setting it as the said upper limit or less, the high viscosity and gelatinization of a novolak-type phenol resin can be suppressed.

  The reaction method of these phenols and aldehydes is not particularly limited. For example, a method in which all phenols and aldehydes are charged and reacted together at the start of the reaction, or phenol is suppressed in order to suppress heat generation at the initial stage of the reaction. It is possible to apply a method in which aldehydes are added in a batch and then reacted by adding aldehydes sequentially.

Although it does not specifically limit as reaction temperature in the said (a) process, It is preferable that it is 40-150 degreeC. More preferably, it is 90-140 degreeC.
By making reaction temperature more than the said lower limit, reaction with phenols and aldehydes can be accelerated | stimulated and content of unreacted phenols can be reduced. Moreover, it can make phosphoric acid aqueous solution into a preferable viscosity, and can avoid that a catalytic action falls. On the other hand, the decomposition of the novolac type phenol resin can be suppressed by setting it to the upper limit value or less.

In the step (a), for example, the reflux temperature in the range of 20 to 40% by weight of water is approximately 102 to 110 ° C., and normal pressure reaction is a preferable condition for controlling the temperature and moisture. As other reaction methods, for example, a solvent reflux dehydration reaction using a non-aqueous solvent such as butanol or propanol, a high pressure reaction, or the like can be applied.
In addition, a reaction method in which aldehydes are sequentially added and condensed water to be generated is removed by distillation or the like can be carried out under preferable reaction conditions because the amount of water in the reaction system is constant. However, when unreacted phenols are easily removed together with moisture, the reaction is performed under the condition that unreacted phenols are not distilled until the unreacted phenols become a certain amount or less. It is preferable to continue the reaction after removing or after removing.

Although it does not specifically limit in the manufacturing method of this invention, After the said (a) process, it is preferable to wash the reaction system with water and to make the density | concentration of phosphoric acid contained in a novolak-type phenol resin into 3 weight% or less. . More preferably, it is 0.1 weight% or less.
Thereby, decomposition | disassembly of a novolak-type phenol resin can be suppressed when performing atmospheric distillation or vacuum distillation after water washing.

  Although it does not specifically limit as a method to wash with water here, For example, the organic phase containing a phenol resin and the aqueous phase containing phosphoric acid aqueous solution are isolate | separated by centrifugation. Next, the obtained organic phase is washed with pure water or ion-exchanged water, whereby the concentration of phosphoric acids contained in the novolac type phenol resin can be reduced to 3% by weight or less. Moreover, the concentration of phosphoric acids can be reduced to 0.1% by weight or less by performing this water washing a plurality of times.

  In the step (a), atmospheric distillation, vacuum distillation, steam distillation or the like can also be carried out in order to remove water, organic solvent, and unreacted phenols, if necessary.

  In the step (a), phosphoric acids are used, but in addition to this, it is also possible to use an acid catalyst usually used in the production of a novolak type phenol resin. Examples of such an acidic catalyst include oxalic acid, sulfuric acid, hydrochloric acid, p-toluenesulfonic acid and the like.

  In the step (a), by reacting phenols and aldehydes with an aqueous phosphoric acid solution, a high yield of novolac phenolic resin with a low content of unreacted phenols and a narrow molecular weight distribution is obtained. The reason that can be obtained by the following is considered.

Phosphoric acids are compounds with very high water solubility, but have low solubility in phenols, and have the property of further decreasing solubility with increasing molecular weight for novolac phenolic resins.
By using a predetermined amount of this aqueous phosphoric acid solution with respect to phenols, the reaction system at the start of the reaction is phase-separated into an organic phase mainly composed of phenols and an aqueous phase composed of an aqueous phosphoric acid solution. In this liquid-liquid heterogeneous reaction system, the phenolic monomer is relatively easily eluted in the aqueous phase, and the eluted component reacts with the added aldehyde by the catalytic action of phosphoric acids. The novolak type phenolic resin produced by the reaction is rapidly extracted into the organic phase, but the novolak type phenolic resin having a high molecular weight is hardly eluted in the aqueous phase, so that the reaction for increasing the molecular weight is less likely to occur.

  In addition, by appropriately adjusting the amount of water and reaction temperature in the reaction system, not only phenolic monomers but also water having low molecular weight components such as dinuclear components and trinuclear components generated by the reaction have phosphoric acid catalysts. Elution into the phase is facilitated, and the reaction in the aqueous phase can easily proceed. Thereby, content of these low nuclear component can be adjusted according to the objective.

Thus, in the reaction system of the step (a), the low molecular weight component and the high molecular weight component cause a reaction rate difference due to the difference in solubility in the aqueous phase, and phenolic monomers, binuclear components, etc. The low molecular weight component selectively reacts and the generated novolac type phenolic resin can be prevented from excessively high molecular weight.
As a result, it is possible to produce a novolac type phenol resin with a low content of unreacted phenols and a narrow molecular weight distribution in a high yield.

The content of unreacted phenols contained in the novolak type phenol resin obtained in the step (a) is not particularly limited, but is preferably 3% by weight or less. More preferably, it is 1 weight% or less.
In the production method of the present invention, in the step (a), phenols and aldehydes are subjected to a liquid-liquid heterogeneous reaction between an organic phase mainly composed of phenols and an aqueous phase composed of an aqueous phosphoric acid solution. By carrying out the step, the content of unreacted phenols can be made the upper limit value or less. Moreover, in order to remove unreacted phenols, atmospheric distillation, vacuum distillation, steam distillation, etc. can also be performed as needed.

The degree of dispersion of the molecular weight distribution of the novolak type phenol resin obtained in the step (a) (dispersion degree = weight average molecular weight / number average molecular weight) is not particularly limited, but is preferably 1.2 to 3.0.
In the production method of the present invention, by performing the liquid-liquid heterogeneous reaction, it is possible to reduce the content of unreacted phenols and suppress an increase in the high molecular weight component. Thereby, the dispersion degree of molecular weight distribution can be made into the said range.

Next, in the production method of the present invention,
(B) The novolac type phenol resin obtained in the step (a) is reacted with aldehydes using an alkaline catalyst to synthesize a resol type phenol resin.

The number of moles of the aldehyde (F ₂ ) used in the step (b) is not particularly limited, but is used in the step (a) with respect to the phenols (P) used in the step (a). In combination with the aldehydes (F ₁ ), the molar ratio [(F ₁ + F ₂ ) / P] is usually 0.8 to 3.0. Preferably it is 1.0-2.5.
If the molar ratio is smaller than the lower limit, the resol resinification reaction may not be sufficiently performed. Moreover, when the said upper limit is exceeded, the residual amount of unreacted aldehydes may increase.

At this time, the addition amount of the alkaline catalyst for resol resinification is not particularly limited, but is usually within a range of 0.01 to 1 mol with respect to 1 mol of phenols used in the step (a). Preferably it is 0.05-0.5 mol.
If it is less than the above lower limit value, the action as a catalyst may not be sufficient, and if it exceeds the above upper limit value, it may affect the curing and may be removed by washing or adding an acidic substance in some cases. Need to be neutralized.

  Although it does not specifically limit as an alkaline catalyst, For example, oxidation of tertiary earth metals, such as lithium hydroxide, potassium hydroxide, ammonia water, a triethylamine, sodium carbonate, hexamethylenetetramine, or alkaline earth metals, such as calcium, magnesium, and barium Materials and hydroxides can be used.

  As the reaction solvent used in the step (b), water is common and preferable, but it may be an organic solvent, and a non-polar solvent may be used in a non-aqueous system. Alternatively, paraform or the like may be used without a reaction solvent. Organic solvents include alcohols, ketones, aromatics, alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, glycerin, etc., and ketones include acetone, methyl ethyl ketone And the aromatics include toluene, xylene and the like.

The resol-type phenolic resin obtained by the production method of the present invention can take the form of an aqueous solution after being converted to a resole resin, but can be dehydrated under reduced pressure or using a dehydrating apparatus such as a thin film evaporator. It is also possible to solidify by. Further, after resol resinization, after dehydration under reduced pressure, it can be dissolved in an organic solvent to take a liquid form.
Accordingly, the form of the resol-type phenol resin obtained by the production method of the present invention is not particularly limited. For example, an aqueous solution of a low-condensation resol-type phenol resin, an organic solvent of a medium-to-high-condensation resol-type phenol resin It can take the form of a solution, an aqueous solution of a resol type phenol resin containing a high concentration of caustic alkali, a powdered resol type phenol resin, and the like.

Although it does not specifically limit as unreacted phenols contained in the resol type phenol resin obtained by the manufacturing method of this invention, It is preferable that it is 3 weight% or less. More preferably, it is 1% by weight. Thereby, it can be set as the resol type phenol resin which is favorable on the environmental sanitation at the time of handling, and suitable for various uses.
According to the production method of the present invention, a novolac type phenol resin is synthesized by reacting a phenol with an aldehyde using an aqueous phosphoric acid solution containing a predetermined amount of phosphoric acid, and the novolac type phenol resin and the aldehyde. To produce a resol-type phenol resin. Preferably, by reacting under the above reaction conditions, a resol-type phenol resin having a low content of unreacted phenols and a low content of aldehydes is obtained. Can be manufactured in high yield

The content of unreacted phenols and unreacted aldehydes in the resol type phenolic resin obtained by the production method of the present invention is sufficiently small. You may combine the process of removing reaction phenols and unreacted aldehydes.
For example, unreacted phenols can be removed by performing a steam distillation method or the like. Unreacted aldehydes can be removed by adding a catching agent for aldehydes such as urea.

  Hereinafter, the present invention will be described in detail with reference to examples. Here, “parts” indicates “parts by weight” and “%” indicates “% by weight”.

(Example 1)
In a 3 L three-necked flask, 1000 parts of phenol and 1000 parts of 85% aqueous phosphoric acid solution are added, the temperature is raised to 100 ° C., 604 parts of 35% aqueous formaldehyde solution are sequentially added over 30 minutes, and the mixture is refluxed at 100 ° C. for 1 hour. The reaction was carried out.
Thereafter, 500 parts of pure water was added and mixed to remove the aqueous phase separated from the resin phase. Such a water washing process was performed 3 times, and the novolak-type phenol resin A1 was obtained.
Then, after adding 30 parts of 50% NaOH aqueous solution and 672 parts of 35% formaldehyde, it heated to 80 degreeC and refluxed for 2 hours. After the reaction, vacuum distillation was performed at 5000 Pa and when the temperature reached 80 ° C., methyl alcohol was added to obtain a resol type phenol resin A2 with a viscosity at 25 ° C. of 1000 mPa · s.

(Example 2)
In a 3 L three-necked flask, add 1000 parts of phenol and 1000 parts of 85% aqueous phosphoric acid solution, raise the temperature to 100 ° C., add 139 parts of 92% paraformaldehyde sequentially over 30 minutes, and reflux at 100 ° C. for 1 hour. The reaction was carried out.
Thereafter, 500 parts of pure water was added and mixed to remove the aqueous phase separated from the resin phase. Such a water washing process was performed 3 times, and the novolak-type phenol resin B1 was obtained.
Then, after adding 50 parts of 50% NaOH aqueous solution and 1276 parts of 35% formaldehyde, the mixture was heated to 70 ° C. and refluxed for 3 hours. After the reaction, vacuum distillation was performed at 5000 Pa and when the temperature reached 80 ° C., methyl alcohol was added to obtain a resol type phenolic resin B2 with a viscosity at 25 ° C. of 1000 mPa · s.

(Example 3)
Add 1000 parts of phenol and 1000 parts of 85% aqueous phosphoric acid solution to a 3 L three-necked flask, heat up to 100 ° C., sequentially add 776 parts of 35% aqueous formaldehyde solution over 30 minutes, and reflux at 100 ° C. for 1 hour. It was made to react.
Thereafter, 500 parts of pure water was added and mixed to remove the aqueous phase separated from the resin. Such a water washing process was performed 3 times, and the novolak-type phenol resin C1 was obtained.
Then, after adding 40 parts of 50% NaOH aqueous solution and 237 parts of 35% formaldehyde, the mixture was heated to 80 ° C. and refluxed for 1 hour, then methyl alcohol was added, and the viscosity at 25 ° C. was set to 1000 mPa · s. A resol type phenol resin C2 was obtained.

Example 4
In a 3 L three-necked flask, 1000 parts of phenol and 1000 parts of 50% aqueous phosphoric acid solution are added, the temperature is raised to 100 ° C., 638 parts of 35% aqueous formaldehyde solution is added successively over 30 minutes, and the mixture is refluxed at 100 ° C. for 1 hour. The reaction was carried out.
Thereafter, 500 parts of pure water was added and mixed to remove the aqueous phase separated from the resin phase. Such a water washing process was performed 3 times, and the novolak-type phenol resin D1 was obtained.
Then, after adding 40 parts of 50% NaOH aqueous solution and 639 parts of 35% formaldehyde, it heated to 80 degreeC and refluxed for 2 hours. After the reaction, vacuum distillation was performed at 5000 Pa and when the temperature reached 80 ° C., methyl alcohol was added to obtain a resol type phenol resin D2 with a viscosity at 25 ° C. of 1000 mPa · s.

(Example 5)
In a 3 L three-necked flask, 1000 parts of phenol and 429 parts of 85% aqueous phosphoric acid solution are added, the temperature is raised to 100 ° C., 690 parts of 35% formaldehyde aqueous solution is added successively over 30 minutes, and the mixture is refluxed at 100 ° C. for 1 hour. The reaction was carried out.
Thereafter, 500 parts of pure water was added and mixed to remove the aqueous phase separated from the resin phase. Such a water washing process was performed 3 times, and the novolak-type phenol resin E1 was obtained.
Then, after adding 40 parts of 50% NaOH aqueous solution and 678 parts of 35% formaldehyde, it heated to 80 degreeC and refluxed for 2 hours. After the reaction, vacuum distillation was performed at 5000 Pa and when the temperature reached 80 ° C., methyl alcohol was added to obtain a resol type phenol resin E2 with a viscosity at 25 ° C. of 1000 mPa · s.

(Comparative Example 1)
While adding 1000 parts of phenol and 10 parts of 85% phosphoric acid into a 3 L three-necked flask, the temperature was raised to 100 ° C., 690 parts of 37% formaldehyde aqueous solution was sequentially added over 30 minutes, and refluxed at 100 ° C. for 1 hour. After reacting, 500 parts of methyl alcohol was added to obtain a novolac-type phenol resin F1.
Then, after adding 40 parts of 50% NaOH aqueous solution and 345 parts of 37% formaldehyde, the mixture was heated to 80 ° C. and refluxed for 1 hour, methyl alcohol was added, and the viscosity at 25 ° C. was set to 1000 mPa · s. A resol type phenol resin F2 was obtained.

(Comparative Example 2)
1000 parts of phenol and 10 parts of oxalic acid are added to a 3 L three-necked flask, the temperature is raised to 100 ° C., 690 parts of a 37% formaldehyde aqueous solution is sequentially added over 30 minutes, and the mixture is allowed to react at reflux for 1 hour at 100 ° C. Then, 500 parts of methyl alcohol was added to obtain a novolac-type phenolic resin G1.
Then, after adding 40 parts of 50% NaOH aqueous solution and 345 parts of 37% formaldehyde, the mixture was heated to 80 ° C. and refluxed for 1 hour, methyl alcohol was added, and the viscosity at 25 ° C. was set to 1000 mPa · s. A resol type phenol resin G2 was obtained.

About the novolak-type phenol resin A1-E1 obtained in the Example, content of the unreacted phenol of the resin after water washing and phosphoric acid density | concentration were measured. About the novolak-type phenol resin F1 and G1 obtained by the comparative example, content of unreacted phenols was measured about the resin after a synthesis | combination.
Moreover, about the resol type phenol resin A2-G2 obtained by the Example and the comparative example, the unreacted phenols and unreacted aldehydes which are contained in the resin after a synthesis | combination were measured.
Table 1 shows the characteristics of the phenol resins obtained in Examples 1 to 5 and Comparative Examples 1 and 2.

(Measuring method)
(1) Number average molecular weight and weight average molecular weight: measured by liquid chromatography.
-Liquid chromatography was performed using GPC (gel permeation chromatography), using tetrahydrofuran as an elution solvent, and measuring under conditions of a flow rate of 1.0 ml / min and a column temperature of 40 ° C. The device
Body: "HLC-8120" manufactured by TOSOH
Analytical columns: one manufactured by TOSOH, “G1000HXL”, two “G2000HXL”, and one “G3000HXL” were used.
(2) Content of unreacted phenols: measured by gas chromatography.
Gas chromatography: Based on JIS K 0114, measurement was performed by an internal standard method using 3,5-xylenol as an internal standard. The measured value is converted to the amount contained in the resin solid content. In addition, about the resol type phenol resin, the thing after reaction (before dilution with a solvent) was sampled and measured.
(3) Content of unreacted aldehydes: measured by hydroxylamine hydrochloride method. The resole type phenolic resin was measured after sampling after reaction (before dilution with a solvent).
(4) Phosphoric acid concentration in phenol resin: measured by fluorescent X-ray method.

Examples 1 to 5 are resol-type phenol resins obtained by the production method of the present invention and have a low content of unreacted phenols and unreacted aldehydes. In addition, since the unreacted phenols could be reduced in the process of synthesizing the novolac type phenol resin without distilling off the unreacted phenols, the resol type phenol resin could be produced efficiently.
In Comparative Example 1, phosphoric acid was used in the step (a), but it was used in a small amount like oxalic acid in Comparative Example 2 and was different from the reaction form according to the production method of the present invention. Therefore, Comparative Example 1 and Comparative Example 2 In both cases, the content of unreacted phenols and unreacted aldehydes was large.

  In the present invention, a novolac phenol resin is synthesized by reacting a phenol and an aldehyde with an aqueous phosphoric acid solution containing a predetermined amount of phosphoric acid, and reacting the novolac phenol resin with the aldehyde. It is a manufacturing method of a resol type phenol resin which has a process, and a resol type phenol resin with few contents of unreacted phenols and aldehydes can be manufactured in high yield. Therefore, the present invention is suitable as a method for industrially producing such a resol type phenol resin.

Claims (10)

A method for producing a resole type phenolic resin,
(A) a step of synthesizing a novolac type phenol resin by reacting phenols and aldehydes with a phosphoric acid aqueous solution containing 0.2 mol or more of phosphoric acid with respect to 1 mol of the phenols;
(B) a step of synthesizing a resol type phenolic resin by reacting the novolac type phenolic resin with an aldehyde using an alkaline catalyst;
A process for producing a resol-type phenolic resin, comprising: The resol type phenol according to claim 1, wherein in the step (a), a reaction molar ratio (F ₁ / P) of phenols (P) and aldehydes (F ₁ ) is 0.3 to 0.95. Manufacturing method of resin. The method for producing a resol-type phenol resin according to claim 1 or 2, wherein in the step (a), the reaction is performed with a water content in the reaction system of 1 to 40% by weight. The method for producing a resol type phenol resin according to any one of claims 1 to 3, wherein the reaction is carried out at a reaction temperature of 40 to 150 ° C in the step (a). The method for producing a resol-type phenol resin according to any one of claims 1 to 4, wherein the phosphoric acid is phosphoric acid. The method for producing a resol type phenol resin according to any one of claims 1 to 5, wherein a concentration of the phosphoric acid in the phosphoric acid aqueous solution is 20 to 99% by weight. The process according to any one of claims 1 to 6, further comprising a step of washing the reaction system with water after the step (a) so that the concentration of the phosphoric acid contained in the novolac type phenol resin is 3 wt% or less. Of producing a resol-type phenolic resin. The method for producing a resol type phenol resin according to any one of claims 1 to 7, wherein unreacted phenols contained in the novolac type phenol resin are 3 wt% or less. The method for producing a resol type phenol resin according to any one of claims 1 to 8, wherein a dispersion degree of a molecular weight distribution of the novolak type phenol resin is 1.2 to 3.0. The method for producing a resol-type phenol resin according to any one of claims 1 to 9, wherein unreacted phenols contained in the resol-type phenol resin are 3% by weight or less.