JP2005194354A - Method for producing solid resol-type phenolic resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently producing a solid resol-type phenolic resin without complicated processes. <P>SOLUTION: The method for producing the solid resol-type phenolic resin comprises (a) the step of reacting a phenol with an aldehyde in the presence of a phosphoric acid to synthesize a novolak-type phenolic resin having an unreacted phenol content of at most 5 wt.% and a weight-average molecular weight (as measured by GPC) of at most 1,500, (b) the step of reacting the novolak-type phenolic resin with an aldehyde in the presence of an alkaline catalyst to synthesize a resol-type phenolic resin, and (c) the step of dehydrating the resol-type phenolic resin to a water content of at most 5 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  The resol-type phenolic resin is usually prepared in a charge molar ratio of 1 to 3 moles of phenol with 1 to 3 moles of aldehyde, and the catalyst is sodium hydroxide, aqueous ammonia, tertiary amine, alkaline earth metal oxide or water. It can be obtained by reacting with an alkaline catalyst such as oxide or sodium carbonate.

Here, as a method for obtaining a solid resol type phenol resin, for example, there is a method in which phenols and aldehydes are reacted using an oxide or hydroxide of a divalent metal as an alkaline catalyst.
The resin thus obtained has many methylene bonds and methylol groups in the ortho position with respect to the hydroxyl groups of phenols, and has a characteristic that the curing speed is fast, but since it has many hydrophilic methylol groups, It has high hygroscopicity and tends to be semi-solid rather than solid. For this reason, there is a problem that handling is difficult.

On the other hand, there is a method of obtaining a hydrophobic solid resol type phenol resin by using ammonia and a tertiary amine as an alkaline catalyst.
In the case of this method, it is necessary to use a large amount because the catalyst used at the time of the reaction hardly forms a solid when the amount is small. This is because the above-described catalyst component (nitrogen-containing compound) undergoes a crosslinking reaction with the resin during the reaction, and the melting point rises and it becomes easy to solidify, but at the same time, the viscosity increases remarkably. In order to obtain a solid resin, a dehydration operation with higher accuracy than that of a liquid resol type phenol resin is required.
However, for example, when dehydration is performed in the reaction apparatus, the molten resin has a considerably high viscosity. However, since resole phenolic resins are generally unstable to heat, the resin is discharged from the reaction apparatus. The temperature and time are limited, and there is a problem that it is difficult to properly maintain the viscosity at the time of discharge.

For such a problem, there are many findings regarding a method for producing a solid resol-type phenol resin, a method for discharging from a reaction apparatus, and a method for dehydration.
For example, as a method of using an apparatus for discharging a resol type phenolic resin, a method of discharging with a rotary blade type kneader / reactor (see, for example, Patent Document 1), a method of discharging with a twin screw extruder (for example, And Patent Document 2), and a method of continuous extrusion using an extruder (for example, see Patent Document 3 or 4).
Further, as a method having both a dehydration step and a discharge step from the reaction apparatus, a method using a fluidized bed type drying device (see, for example, Patent Document 5) or a method using a thin film evaporator (for example, Patent Documents 6 to 8). And a device using a heating continuous vacuum dryer (for example, see Patent Document 9).
However, each of these requires a dedicated accessory device, which reduces the flexibility of production facilities, production volume, and the like, leading to a decrease in production efficiency and an increase in production cost.

JP 49-083990 A JP 54-083990 A Japanese Patent Publication No. 61-044884 Japanese Patent Laid-Open No. 54-028357 JP-A-53-243090 JP 56-167719 A JP 59-053519 A JP 58-103520 A Japanese Patent Laid-Open No. 01-230615

  Said problem is solved by improving the characteristic of solid resol type phenol resin, and enabling discharge | emission from a reactor, without using an additional installation. In other words, the problem can be solved by achieving a melt viscosity property of a resol type phenolic resin that has not been heretofore, specifically, a high melting point and a low melt viscosity. Such a resol type phenolic resin can maintain a low viscosity when discharged from the reaction apparatus, and can prevent caking and stickiness during transportation, pulverization, storage, and the like.

Normally, a solid resol type phenol resin contains about several weight percent of unreacted phenols, but it is known that the melting point is lowered when unreacted phenols are included. Therefore, if the amount of unreacted phenols is reduced, the melting point can be increased. Also, by reducing the proportion of methylol groups in the resol-type phenolic resin and increasing the proportion of methylene bonds, a significant increase in viscosity when using nitrogen-containing compounds as a catalyst is suppressed, and a low melt viscosity is achieved. Can do.
Such a resol type phenol resin can be obtained by synthesizing a novolak type phenol resin having a small content of unreacted phenols and a relatively small molecular weight, and then converting it into a resol resin.

  The present invention provides a method for efficiently producing a solid resol type phenolic resin without going through complicated steps.

Such an object is achieved by the following present inventions (1) to (3).
(1) A method for producing a solid resol type phenolic resin,
(A) A step of reacting phenols and aldehydes with phosphoric acids to synthesize a novolak type phenol resin having a content of unreacted phenols of 5% by weight or less and a weight average molecular weight by GPC measurement of 1500 or less. ,
(B) a step of reacting the novolac type phenolic resin with an aldehyde using an alkaline catalyst to synthesize a resol type phenolic resin, and
(C) a step of dehydrating so that the water content in the resol type phenolic resin is 5% by weight or less;
A process for producing a solid resol-type phenolic resin, comprising:
(2) The manufacturing method of the solid resol type phenol resin as described in said (1) using the said phosphoric acids 0.2 mol or more with respect to 1 mol of said phenols.
(3) The manufacturing method of the solid resol type phenol resin as described in said (1) or (2) whose said phosphoric acids are phosphoric acid.

  The solid resol type phenolic resin obtained by the production method of the present invention has a high melting point, a low melt viscosity, and excellent handleability. The production method of the present invention can efficiently produce a solid resol type phenol resin having such properties without going through complicated steps.

Below, the manufacturing method (henceforth "a manufacturing method") of the solid resol type phenol resin of this invention is demonstrated in detail.
The production method of the present invention comprises:
(A) A step of reacting phenols and aldehydes with phosphoric acids to synthesize a novolak type phenol resin having a content of unreacted phenols of 5% by weight or less and a weight average molecular weight by GPC measurement of 1500 or less. ,
(B) a step of reacting the novolac type phenolic resin with an aldehyde using an alkaline catalyst to synthesize a resol type phenolic resin, and
(C) a step of dehydrating so that the water content in the resol type phenolic resin is 5% by weight or less;
It is characterized by having.

In the production method of the present invention, first,
(A) Phenols and aldehydes are reacted with phosphoric acids to synthesize a novolak type phenol resin having a content of unreacted phenols of 5% by weight or less and a weight average molecular weight by GPC measurement of 1500 or less.

  Although it does not specifically limit as phenols used here, For example, cresol, such as phenol, o-cresol, m-cresol, 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, isopropylphenol, butylphenol, p-tert-butylphenol Alkylphenols such as butylphenol, p-tert-amylphenol, p-octylphenol, p-nonylphenol, p-cumylphenol, and the like, fluorophenols, chlorophenol, bromophenol, iodophenol, etc. Monovalent phenol substitutes such as genated phenol, p-phenylphenol, aminophenol, nitrophenol, dinitrophenol and trinitrophenol, and monovalent polycyclic phenols such as 1-naphthol and 2-naphthol, resorcin, alkyl Examples thereof include polyphenols such as resorcin, 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. Usually, phenol, cresol, and bisphenol A are often used.

  The aldehydes used here are not particularly limited, but examples include formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butyraldehyde, capro Examples include aldehyde, allyl aldehyde, benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde and the like. These can be used alone or in combination of two or more. Usually, formaldehyde is often used.

The reaction molar ratio of the phenols and aldehydes used in the step (a) is not particularly limited, but the reaction molar ratio (F ₁ / P) of the aldehydes (F ₁ ) to the phenols (P) is 0.3. It is preferable that it is -0.9, More preferably, it is 0.4-0.8.
Thereby, a novolak-type phenol resin having a proper weight average molecular weight and a small content of unreacted phenols can be obtained. When the reaction molar ratio is smaller than the lower limit, the reaction consumption of phenols does not proceed sufficiently, and even when this is converted into a resole resin, the content of unreacted phenol may not be sufficiently reduced. Further, if the above upper limit is exceeded, the molecular weight of the novolak type phenol resin becomes large, and when this is converted into a resole resin, it may be gelled depending on the reaction conditions.

  In the production method of the present invention, phosphoric acids are used as an acidic catalyst in the synthesis of the novolak type phenol resin.

  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 at the time of using phosphoric acid as 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 here is not particularly limited, but is preferably 0.2 mol or more with respect to 1 mol of phenols. Thereby, in the system which reacts phenols and aldehydes using phosphoric acids, distribution of the organic phase which has phenols as a main component and the aqueous phase which has 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, the novolak-type phenol resin with little content of unreacted phenols can be obtained efficiently.

  Increasing the amount of phosphoric acid tends to increase the effect of obtaining a high yield of novolak-type phenol resin with a low content of unreacted phenols, but 1.0 mol per mol of phenols. Even if an amount exceeding 1 is used, this effect may not be substantially changed, so that it may not be economical. 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.

  Although it does not specifically limit as reaction conditions in the said (a) process, It is preferable that reaction temperature 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.

Moreover, it is although it does not specifically limit as a moisture content rate in the reaction system at the time of reaction, It is preferable to set it as 1 to 40 weight%. More preferably, it is 1 to 30% by weight.
Here, the water content in the reaction system is the weight of the total amount of water present in the reaction system with respect to the total amount of phenols, aldehydes, phosphoric acids, novolac-type phenol resin, etc. present in the reaction system. Refers to the ratio. The water present in the reaction system includes water derived from the raw material to be added, such as water contained 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 in 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.

  Such reaction conditions are effective for selectively reacting not only unreacted phenols but also low molecular weight components such as dinuclear components, and narrowing the molecular weight distribution of the resulting novolak type phenol resin. Can do. That is, the reaction of unreacted phenols proceeds sufficiently even outside the range of the above reaction conditions, but for the selective reaction of a low molecular weight component such as a binuclear component, it is within the range of the above reaction conditions. It is effective to do.

  In addition, there is no restriction | limiting in particular about reaction time, According to the kind of phenols and aldehydes, reaction molar ratio, the kind and usage-amount of a catalyst, reaction conditions, etc., it can select suitably.

In the step (a), when the phenols and aldehydes are reacted under normal pressure using phosphoric acids, for example, the reflux temperature in the range where the water content is 20 to 40% by weight is approximately 102 to 110 ° C. Thus, the atmospheric 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.

  In the step (a), phosphoric acid is used as a catalyst, but in addition, it is possible to use an acidic catalyst such as oxalic acid, sulfuric acid, hydrochloric acid, p-toluenesulfonic acid, which is usually used in the production of a novolak type phenol resin. It is. The combined use of these acidic catalysts is effective for accelerating the reaction particularly when a high molecular weight component higher than the tetranuclear component is required, and is an effective means for controlling the molecular weight distribution.

  The reaction method of the above phenols and aldehydes is not particularly limited. For example, at the start of the reaction, all the phenols and aldehydes are charged all at once and reacted under a catalyst, or exothermic heat at the beginning of the reaction. In order to suppress this, there may be mentioned a method in which phenols and a catalyst are charged and then aldehydes are sequentially added and reacted therewith.

The production method of the present invention is not particularly limited, but after synthesizing the novolak type phenol resin by the method described above, the reaction system is washed with water, and the concentration of phosphoric acid contained in the novolac type phenol resin is set to 3. It is preferable to make it 0% by 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. Subsequently, the obtained organic phase is washed with pure water or ion-exchanged water, whereby the concentration of phosphoric acids contained in the novolak type phenol resin can be reduced to 3.0% 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.

  Further, after washing with water until the concentration of phosphoric acid is not more than the above upper limit, 0.8 to 1.5 equivalents of alkaline substance is used for 1 equivalent of phosphoric acid remaining in the reaction system. Can be neutralized. Thereby, since the catalytic activity which phosphoric acids have can be deactivated, even when performing a dehydration reaction at a high temperature in the subsequent steps, decomposition of the novolac type phenol resin can be suppressed. Further, an excessive amount of an alkaline substance can be added to make a resole resin as it is.

  In the step (a), water, an organic solvent, and further unreacted phenols can be removed if necessary, and atmospheric distillation, vacuum distillation, steam distillation, or the like can also be performed.

  In the step (a) of the production method of the present invention, a novolak type having a small content of unreacted phenols and a small weight average molecular weight is obtained by reacting phenols and aldehydes with phosphoric acids. The reason why the phenol resin can be obtained in a high yield is considered as follows.

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 phosphoric acid 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 containing an aqueous solution of phosphoric acids. In this liquid-liquid heterogeneous reaction system, low molecular weight components such as phenolic monomers and dinuclear components are relatively easily eluted in the aqueous phase, and the eluted components react with aldehydes 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.

  Also, by setting the water content and reaction temperature in the reaction system preferably within the above ranges, low molecular weight components such as dinuclear components and trinuclear components generated by the reaction are eluted into the aqueous phase containing phosphoric acids. And the reaction in the aqueous phase can easily proceed. And since the ion concentration in a water phase is maintained in the state where it is high, the interface of a water phase and an organic phase isolate | separates more firmly, and the polymeric reaction on the organic phase side can be prevented.

Thus, in the reaction system according to the production method of the present invention, the low molecular weight component and the high molecular weight component of the novolak type phenol resin cause a difference in reaction rate due to the difference in solubility in the aqueous phase, and the phenol monomers and While low molecular weight components, such as a binuclear component, react selectively, it can suppress that the produced novolak-type phenol resin becomes high molecular weight too much.
As a result, it is possible to produce a novolac phenolic resin with a low content of unreacted phenols and a small weight average molecular weight in a high yield.

In the production method of the present invention, the content of unreacted phenols in the novolak-type phenol resin obtained by the above method is 5% by weight or less. Thereby, when it uses a novolak type phenol resin as a raw material and makes a resol type phenol resin, it can be made high melting point and low melt viscosity. The content of unreacted phenols is more preferably 3% by weight or less.
In the production method of the present invention, phenols and aldehydes are used as phosphoric acids, and a liquid-liquid heterogeneous reaction is performed between an organic phase mainly composed of phenols and an aqueous phase containing phosphoric acids. Thereby, content of unreacted phenols can be made into the said upper limit or less. Moreover, in order to remove unreacted phenols, atmospheric distillation, vacuum distillation, steam distillation, etc. can also be performed as needed.

Moreover, in the manufacturing method of this invention, the weight average molecular weight by GPC measurement of a novolak-type phenol resin is 1500 or less. Thereby, a resol type phenol resin having a low melt viscosity can be synthesized using this novolac type phenol resin as an intermediate raw material.
If the weight average molecular weight of the novolak-type phenol resin exceeds 1500, the viscosity at the time of the resole resinization reaction tends to increase and the gelation easily occurs. The reaction molar ratio of aldehydes to aldehydes must be kept low, and in this case, only resole resins having a low mechanical strength of the cured product tend to be obtained. The weight average molecular weight is more preferably 1350 or less.
In the production method of the present invention, by performing the liquid-liquid heterogeneous reaction, the content of unreacted phenols can be reduced, and an increase in the high molecular weight component can be suppressed. Thereby, a weight average molecular weight can be made into the said lower limit or less.

In the production method of the present invention, the content of unreacted phenols is a value measured by an internal standard method using 3,5-xylenol as an internal standard substance using a gas chromatography method in accordance with JIS K 0114. It is.
The weight average molecular weight was measured using a GPC (gel permeation chromatography) method, using tetrahydrofuran as an elution solvent, a flow rate of 1.0 ml / min, and a differential refractometer at a column temperature of 40 ° C. Was measured as a detector, and the molecular weight was converted with standard polystyrene. The device
1) Body: "HLC-8120" manufactured by TOSOH
2) Analytical columns: 1 “G1000HXL”, 2 “G2000HXL” and 1 “G3000HXL” manufactured by TOSOH were used.

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

  Although it does not specifically limit as aldehydes here, For example, formaldehyde, paraformaldehyde, trioxane, acetaldehyde, propionaldehyde, polyoxymethylene, chloral, hexamethylenetetramine, furfural, glyoxal, n-butyraldehyde, caproaldehyde, allylaldehyde Benzaldehyde, crotonaldehyde, acrolein, tetraoxymethylene, phenylacetaldehyde, o-tolualdehyde, salicylaldehyde and the like. These can be used alone or in combination of two or more. Usually, formaldehyde is often used.

The alkaline catalyst used in the step (b) is not particularly limited, and examples thereof include alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide, tertiary amines such as ammonia water and triethylamine, Examples thereof include oxides and hydroxides of alkaline earth metals such as calcium, magnesium and barium, sodium carbonate, hexamethylenetetramine and the like.

The reaction molar ratio of the aldehydes (F ₂ ) in the step (b) is not particularly limited, but when synthesizing the novolac type phenol resin to the phenols (P) used when synthesizing the novolac type phenol resin. with aldehydes _{(F 1)} and the total molar ratio of _{[(F 1 + F 2)} / P] used in is preferably 0.9 to 3.0. More preferably, it is 1.0-2.5.
If the reaction molar ratio is smaller than the lower limit, resol resinification may be insufficient, and if the upper limit is exceeded, many unreacted aldehydes remain in the resol type phenol resin.

  The addition amount of the alkaline catalyst is not particularly limited, but is usually within a range of 0.01 to 1 mol, preferably 0.05 to 0.5 mol, with respect to 1 mol of phenols used in the step (a). It is. If it is lower than 0.01 mol, the action as a catalyst may not be sufficient, and if it exceeds 1 mol, it may affect the curing, so it can be removed by washing with water or adding an acidic substance. It is preferable to neutralize.

The resol type phenolic resin thus obtained has a sufficiently low content of unreacted phenols in the resin. In order to further remove the unreacted phenols, for example, a steam distillation method or the like is used. It can also be removed by doing.
Unreacted aldehydes can be removed by adding a catching agent for aldehydes such as urea.

In the production method of the present invention, water is generally and preferably used as the reaction solvent in any of the above steps (a) and (b), but an organic solvent may be used, and a nonpolar solvent may be used. Can also be used in a non-aqueous system. Alternatively, paraform or the like may be used without a reaction solvent.
Examples of the organic solvent include alcohols, ketones, aromatics and the like. Examples of alcohols include methanol, ethanol, propyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, and glycerin. Examples of ketones include acetone and methyl ethyl ketone. Examples of aromatics include toluene and xylene. .

Next, in the production method of the present invention,
(C) Dehydration treatment is performed so that the water content in the resol type phenolic resin is 5% by weight or less.

  In general, a resol type phenolic resin has a lower melting point when it contains moisture. When trying to obtain a solid resol type phenolic resin, solidification is hindered by this moisture, so dehydration is performed. However, a more accurate dehydration operation is required than when synthesizing a liquid resol type phenolic resin. is there.

In the production method of the present invention, as a dehydration method after synthesizing the resol type phenol resin, vacuum dehydration is generally preferred, but normal pressure dehydration may be used. For example, the degree of vacuum during dehydration under reduced pressure is preferably 30000 Pa or less, more preferably 20000 Pa or less. When the value is larger than 30000 Pa, the time for the dehydration process becomes longer, and the resin characteristics may change during that time. By such an operation, the water content in the resol type phenol resin can be reduced to 5% by weight or less.
Although these methods can sufficiently remove moisture, a process using a conventionally known moisture removal facility may be combined for further removal. For example, moisture can be removed by using a thin film evaporator and spray drying.

  Moreover, after synthesizing the resol type phenol resin in the step (b), an acidic substance is added as necessary, and the stability of the resol type phenol resin when discharged from the reaction apparatus is increased by neutralizing the alkaline catalyst. be able to. As the acidic substance to be added, any of inorganic acids and organic acids can be used. When these acidic substances are used and neutralized, the curing speed can be adjusted by adding a basic or acidic substance at the time of curing.

As described above, in the production method of the present invention, after synthesizing a novolak-type phenol resin from phenols and aldehydes, it is further reacted with aldehydes under an alkaline catalyst and subjected to a predetermined dehydration treatment to form a solid resol type. Synthesize phenolic resin.
Here, by using phosphoric acids when synthesizing the novolak-type phenol resin, a novolak-type phenol resin having a small content of unreacted phenols and a small weight average molecular weight can be obtained.
Then, using the obtained novolak type phenolic resin as an intermediate raw material, a necessary amount of aldehydes are added to this to form a resole resin, and then through a dehydration step, the content of unreacted phenols is low and the melting point is high. -A solid resol type phenol resin having a low melt viscosity can be produced efficiently.

  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 three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol and 1000 parts of 85% phosphoric acid aqueous solution (corresponding to 0.82 mol per mol of phenol) were added, and the temperature was raised to 100 ° C., 37 604 parts of a% formaldehyde aqueous solution (molar ratio [F ₁ /P]=0.7) were sequentially added over 2 hours, and reacted at 100 ° C. for 1 hour under reflux. Thereafter, in order to remove the residual catalyst, 500 parts of pure water was added and mixed, and the aqueous phase separated from the resin phase was removed. Such a water washing process was performed 3 times, and the novolak-type phenol resin was obtained.
Next, after adding 431 parts of 37% formaldehyde (molar ratio [(F ₁ + F ₂ ) / P] = 1.2), 20 parts of calcium hydroxide was added and heated to 80 ° C., and the reflux reaction was continued for 1 hour. went. After the reaction, distillation under reduced pressure was carried out at 17500 Pa, and after reaching 95 ° C., it was taken out from the flask to obtain 1290 parts of a resol type phenol resin.

<Example 2>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol and 1000 parts of 85% phosphoric acid aqueous solution (corresponding to 0.82 mol per mol of phenol) were added, and the temperature was raised to 100 ° C., 37 517 parts of a% formaldehyde aqueous solution (molar ratio [F ₁ /P]=0.6) were sequentially added over 2 hours, and reacted at 100 ° C. for 1 hour under reflux. Thereafter, in order to remove the residual catalyst, 500 parts of pure water was added and mixed, and the aqueous phase separated from the resin phase was removed. Such a water washing process was performed 3 times, and the novolak-type phenol resin was obtained.
Next, after adding 561 parts of 37% formaldehyde (molar ratio [(F ₁ + F ₂ ) / P] = 1.25), 60 parts of 25% aqueous ammonia was added, and the mixture was heated to 100 ° C., and the reflux reaction was performed at 2%. Went for hours. After the reaction, distillation under reduced pressure was performed at 17500 Pa, and after reaching 90 ° C., the product was taken out from the flask to obtain 1234 parts of a resol type phenol resin.

<Example 3>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol and 1000 parts of 85% phosphoric acid aqueous solution (corresponding to 0.82 mol per mol of phenol) were added, and the temperature was raised to 100 ° C., 37 431 parts of a% formaldehyde aqueous solution (molar ratio [F ₁ /P]=0.5) were sequentially added over 2 hours, and reacted at reflux at 100 ° C. for 1 hour. Thereafter, in order to remove the residual catalyst, 500 parts of pure water was added and mixed, and the aqueous phase separated from the resin phase was removed. Such a water washing process was performed 3 times, and the novolak-type phenol resin was obtained.
Next, after adding 604 parts of 37% formaldehyde (molar ratio [(F ₁ + F ₂ ) / P] = 1.2), 30 parts of calcium hydroxide is added and heated to 80 ° C., and the reflux reaction is performed for 1 hour. went. After the reaction, distillation under reduced pressure at 17500 Pa was performed, and after reaching 95 ° C., the flask was taken out from the flask to obtain 1285 parts of a resol type phenol resin.

<Example 4>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol and 429 parts of an 85% aqueous phosphoric acid solution (corresponding to 0.35 moles per mole of phenol) were added, the temperature was raised to 100 ° C., 37 604 parts of a% formaldehyde aqueous solution (molar ratio [F ₁ /P]=0.7) were sequentially added over 2 hours, and reacted at 100 ° C. for 1 hour under reflux. Thereafter, in order to remove the residual catalyst, 500 parts of pure water was added and mixed, and the aqueous phase separated from the resin phase was removed. Such a water washing process was performed 3 times, and the novolak-type phenol resin was obtained.
Next, after adding 431 parts of 37% formaldehyde (molar ratio [(F ₁ + F ₂ ) / P] = 1.2), 20 parts of calcium hydroxide was added and heated to 80 ° C., and the reflux reaction was continued for 1 hour. went. After the reaction, acetic acid was added until the pH was 6.0, and then distilled under reduced pressure at 17500 Pa and reached 95 ° C., and then taken out from the flask to obtain 1278 parts of a resol type phenol resin.

<Example 5>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol and 1000 parts of 85% phosphoric acid aqueous solution (corresponding to 0.82 mol per mol of phenol) were added, and the temperature was raised to 100 ° C., 37 690 parts of a% formaldehyde aqueous solution (molar ratio [F ₁ /P]=0.8) was sequentially added over 2 hours, and reacted at 100 ° C. for 1 hour under reflux. Thereafter, in order to remove the residual catalyst, 500 parts of pure water was added and mixed, and the aqueous phase separated from the resin phase was removed. Such a water washing process was performed 3 times, and the novolak-type phenol resin was obtained.
Next, after adding 431 parts of 37% formaldehyde (molar ratio [(F ₁ + F ₂ ) / P] = 1.3), 40 parts of calcium hydroxide was added and heated to 80 ° C., and the reflux reaction was performed for 1 hour. went. After the reaction, acetic acid was added until the pH was 6.0, and then distilled under reduced pressure at 17500 Pa and reached 95 ° C., and then taken out from the flask to obtain 1300 parts of a resol type phenol resin.

<Comparative Example 1>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol, 1294 parts of 37% formaldehyde (molar ratio F / P = 1.5), and 40 parts of a 50% aqueous sodium hydroxide solution as a catalyst were added, and 100 ° C. For 4 hours. After the reaction, vacuum distillation was performed at 17500 Pa, and then the flask was taken out from the flask at 68 ° C. to obtain 1680 parts of a resol type phenol resin.

<Comparative example 2>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol, 1380 parts of 37% formaldehyde (molar ratio F / P = 1.6), and 60 parts of 25% aqueous ammonia as a catalyst were added. Reacted for 1 minute. After the reaction, vacuum distillation was performed at 17500 Pa, and after reaching 95 ° C., the flask was taken out from the flask to obtain 1265 parts of a resol type phenol resin.

<Comparative Example 3>
In a three-necked flask equipped with a stirrer and a thermometer, 1000 parts of phenol and 10 parts of oxalic acid were charged and heated to 100 ° C., and then 604 parts of 37% formaldehyde (molar ratio [F ₁ /P]=0.7). Were added over 2 hours. Thereafter, in order to neutralize the catalyst, calcium hydroxide was added until the pH became 7.0 to obtain a novolac type phenol resin.
Next, after adding 431 parts of 37% formaldehyde (molar ratio [(F ₁ + F ₂ ) / P] = 1.2), 20 parts of calcium hydroxide was added and heated to 100 ° C., and the reflux reaction was continued for 4 hours. went. After the reaction, distillation under reduced pressure was performed at 17500 Pa, and after reaching 95 ° C., it was taken out from the flask to obtain 1258 parts of a resol type phenol resin.

  Table 1 shows the novolak-type phenol resin and resol-type phenol resin obtained in Examples 1 to 5 and Comparative Examples 1 to 3.

(Note to table)
(1) Gelation time: Measured using 2 ml of resin on a hot plate at 150 ° C. according to JIS K 6909.
(2) Melting point: Measured according to JIS B 7411.
(3) Melt viscosity: C. I. The viscosity at 110 ° C. was measured with a cone plate.
(4) Amount of unreacted phenols: Measured by an internal standard method according to JIS K 0114 using 3,5-xylenol as an internal standard substance.
(5) Weight average molecular weight: Measured using GPC (gel permeation chromatography) method, using tetrahydrofuran as an elution solvent, a flow rate of 1.0 ml / min, and a differential refractometer under a column temperature of 40 ° C. Was measured as a detector, and the molecular weight was converted with standard polystyrene. The device
1) Body: "HLC-8120" manufactured by TOSOH
2) Analytical columns: 1 “G1000HXL”, 2 “G2000HXL” and 1 “G3000HXL” manufactured by TOSOH were used.
(6) Water content: measured by Karl Fischer method.
(7) Yield: calculated according to the following formula.
Yield (%) = 100 × (Resol type phenol resin yield-water content) / (Feed-up material-water content in formaldehyde aqueous solution)

In all of Examples 1 to 5, a resol type phenol resin obtained by the production method of the present invention in which a novolak type phenol resin obtained by reacting phenols and aldehydes with phosphoric acid is converted into a resole resin The content of unreacted phenols was small, the melting point was high, the melt viscosity was low, and the yield was good.
In Comparative Example 1, a resol-type phenol resin was produced in one stage using a divalent metal hydroxide. However, the melt viscosity was higher than that of the Examples, the melting point was low, and there was stickiness, and it did not solidify.
In Comparative Example 2, a resol type phenolic resin was produced in one stage using an ammonia catalyst, but the melt viscosity increased greatly and the yield decreased.
In Comparative Example 3, a novolak-type phenol resin was synthesized using a normal acidic catalyst and then converted into a resole resin. However, since the content of unreacted phenols is large, the melting point is low, and there is stickiness. It did not solidify.

The present invention comprises reacting phenols and aldehydes with phosphoric acids to synthesize a novolak type phenol resin having an unreacted phenol content of 5% by weight or less and a weight average molecular weight by GPC measurement of 1500 or less. A method for producing a solid resol type phenolic resin characterized by having a step of dehydrating the water content to be 5% by weight or less after synthesizing the resol type phenolic resin from this and passing through complicated steps Therefore, a solid resol type phenol resin can be produced with high yield.
The resol type phenol resin obtained by the production method of the present invention is suitably used as a binder for, for example, a grindstone, abrasive cloth, friction material, molding material, laminate, adhesive, paint, and foam.

Claims (3)

A method for producing a solid resol type phenolic resin, comprising:
(A) A step of reacting phenols and aldehydes with phosphoric acids to synthesize a novolak type phenol resin having a content of unreacted phenols of 5% by weight or less and a weight average molecular weight by GPC measurement of 1500 or less. ,
(B) a step of reacting the novolac-type phenol resin with aldehydes using an alkaline catalyst to synthesize a resol-type phenol resin, and (c) a water content in the resol-type phenol resin is 5% by weight or less. The dehydration process,
A process for producing a solid resol-type phenolic resin, comprising: The manufacturing method of the solid resol type phenol resin of Claim 1 using the said phosphoric acid 0.2 mol or more with respect to 1 mol of said phenols. The method for producing a solid resol type phenol resin according to claim 1, wherein the phosphoric acid is phosphoric acid.