JPH10195158A - Production of novolac phenolic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a high-ortho type novolac phenolic resin having a low content of ionic impurities and a high curing rate safely within a short time in good yields. SOLUTION: A phenol and an aldehyde are subjected to an addition condensation reaction in such a manner that formalin having a formic acid content lowered to 200ppm or below or paraformaldehyde (purity of 80% or above) mixed with a phenol is gradually added to and reacted with a phenol heated to 160 deg.C or above in a high-pressure reactor 2 having two-stage same-diameter turbine impellers 1 and pressurized with an inert gas to 0.5Mpa or above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a novolak-type phenolic resin, and more particularly to a method for efficiently producing a high-ortho-type novolak-type phenolic resin having very little ionic impurities and excellent curability. .

[0002]

2. Description of the Related Art A general method for producing a novolak type phenol resin is as follows. A phenol and an aldehyde are used as a catalyst with a known organic acid and / or an inorganic acid as a catalyst at normal pressure of 100.degree.
Is known for performing an addition condensation reaction for several hours, followed by dehydration and removal of unreacted monomers. The novolak-type phenolic resin produced by such a method has many para-position bonds to the ortho-position methylene bond of phenols. The curability was inferior to that of a novolak type phenol resin of the type (hereinafter referred to as high ortho novolak).

On the other hand, the conventional industrial production of high ortho-novolaks is carried out by direct addition of phenols and aldehydes after weakly acidic addition-condensation reaction with a metal salt catalyst such as zinc acetate, lead acetate, zinc naphthenate or the like. Further, a method is generally used in which a condensation reaction is carried out while adding an acid catalyst while dehydrating, and a step for removing unreacted substances is further provided as necessary (for example, JP-A-55-90523, JP-A-59-80).
418, and JP-A-62-230815), but in such a method, there is a problem of productivity such as a long time in the reaction and dehydration steps, and a metal ion is contained in the resin and the cured product is heat resistant. There is a problem that properties such as water resistance, electrical insulation and the like are inferior and cannot be used particularly in applications in the electric and electronic fields where ionic impurities are rejected.

[0004] As a method for producing a high orthonovolak using a catalyst other than a metal salt, a catalyst other than a metal salt catalyst is used in the reaction of a phenol with an aldehyde.
For example, an acid capable of sublimation decomposition such as oxalic acid and a non-polar solvent are added, and the water and the solvent are evaporated at a temperature of 110 ° C. or more, and only the solvent is returned to the reaction system. A method in which the reaction is carried out for 1 to 10 hours (for example, see
However, such a method not only requires a long reaction time, but also a step of raising and decomposing a catalyst in order to reduce ionic impurities, as well as a non-polar solvent. There is a problem that a removing step is required.

Further, as a method for producing a high orthonovolak without using a catalyst, a phenol and paraformaldehyde are mixed using a non-polar solvent such as xylene, and then mixed.
A method in which the reaction is carried out in a pressurized vessel at 0 to 220 ° C. for 12 to 20 hours (for example, Casiraghi, et al., Makrom
ol. Chem. 182 (11), 2973, (198
1) and JP-A-6-345837). In particular, the Makromol. Chem. States that a resin having a very high ratio of methylene bonds at the ortho position can be obtained by such a production method.On the other hand, these methods require a long time for the reaction, and are described in the literature. However, when the reaction temperature is increased, the aldehydes react at once because a predetermined amount is present from the beginning,
There is a problem that the reaction pressure cannot be controlled.In addition, the common points of the method using a non-polar solvent are that the solvent removal step is necessary, the handling is safe, and the yield per batch in the case of batch production. It is not always excellent as an industrial method for producing high-ortho novolak because of the problems that it cannot be increased.

[0006]

The present inventors have made intensive studies to overcome these problems, and as a result, successively inject aldehydes into phenols heated and pressurized in a reactor without using a catalyst. By mixing, more preferably, paraformaldehyde mixed with formalin or phenols in which formic acid is reduced as aldehydes, and a reactor having a two-stage (preferably the same diameter) turbine-type stirring blade Excellent in curability, extremely low in ionic impurities, suitable for molding materials for electric and electronic fields, curing agent for epoxy resin, laminated boards, etc. It has been found that high ortho-novolaks having excellent heat resistance and electrical insulation properties can be produced easily and very efficiently in terms of reaction safety, leading to the present invention. It is intended.

[0007]

According to the present invention, when a phenol and an aldehyde are reacted without using a catalyst, the phenol is heated to 160 ° C. or more in advance and then heated to 0.5 MPa or more with an inert gas. Pressurization, the addition of aldehydes sequentially, the addition temperature while maintaining the reaction temperature of 160 ℃ or more, relates to a method for producing a novolak type phenolic resin, preferably the addition of aldehydes from the bottom of the reactor Further, as aldehydes, formalin from which formic acid is preferably removed to 200 PPM or less or paraformaldehyde having a purity of 80% or more dissolved or suspended in phenols is used, and a reactor (preferably having the same diameter) is used. The present invention relates to a method for producing the same resin, characterized in that a resin having a two-stage turbine type stirring blade is used. Is shall.

Here, as the phenol, one or more compounds having a phenolic hydroxyl group such as phenol, cresol and bisphenol are used. The phenols are heated to 160 ° C. or higher, preferably 180 to 230 ° C. in a reactor, and 0.5 MPa or higher, preferably 0.7 M with a known inert gas such as nitrogen gas.
Pressurize to Pa or more. Initial heating temperature of phenols 16
When the temperature is 0 ° C. or lower, not only the reaction rate at the start of the addition of the aldehydes is slowed, but also the methylene bond at the para position is promoted, and it becomes difficult to obtain the target high ortho novolak. The initial pressurization with an inert gas, of course, includes the meaning of preventing oxidative coloring, but prevents the reaction temperature from decreasing due to latent heat of vaporization of the condensed water in the raw materials and the condensation reaction, and 0.5 MPa With the following pressurization, the reaction temperature decreases immediately after the start of the reaction, and the target temperature cannot be maintained.

Next, the aldehydes are successively added into the reactor, preferably from the lower part of the reactor in view of the reaction efficiency of the aldehyde. Although the molar ratio of the aldehyde to the phenol is not particularly limited, it is generally in the range of 0.3 to 1.0. The aldehyde used in the present invention is one or more having an aldehyde group such as formaldehyde, paraformaldehyde and polyoxymethylene, and one of them is preferably treated with a known ion exchange resin or the like. 200 formic acid
Formalin with PPM or less, and the other one with a purity of 8
0% or more paraformaldehyde.

[0010] Formalin is an aqueous formaldehyde solution, preferably having a concentration of 37% or more, more preferably 40% or more. Formaldehyde easily generates formic acid during the production and storage of formalin by the Cannizzaro reaction, but this formic acid contains not only ionic impurities that cannot be completely decomposed in the formed resin, but also the addition condensation of phenols and aldehydes. It acts as an acid catalyst during the reaction and promotes the methylene bond at the para-position.
More preferably, it must be removed to 50 PPM or less.

[0011] Paraformaldehyde is 80% pure
It is preferable to use the above. If the purity is low, the degree of ortho-position methylene bond decreases, which is not preferable. Generally, paraformaldehyde is a solid substance, and it is difficult to sequentially add heated phenols to a liquid. In the present invention, in order to facilitate the sequential addition, it is essential that a part of paraformaldehyde and phenols are previously mixed and dissolved, or a slurry is formed.
The mixing ratio of paraformaldehyde and phenols is not particularly limited, but is preferably a ratio that can ensure fluidity that can be handled by a known high-pressure pump or slurry pump.
In this case, the amount of phenol required for mixing paraformaldehyde is regarded as a part of the phenol heated in the reactor, and the molar ratio and the like are calculated.

For the sequential addition of aldehydes, known high-pressure pumps such as plunger type and diaphragm type, single-shaft eccentric screw pumps of rotary displacement type (for example, Mono pump manufactured by Hyojin Kiki Co., Ltd.), and slurry pumps such as tube pumps, etc. And preferably supplied quantitatively into the heated phenols from the lower part of the reactor. At this time, the addition rate is preferably set to 15 minutes to 2 hours, as long as the reaction temperature is maintained at 160 ° C. or higher and excessive reaction heat is not generated by a sudden reaction or an excessive pressure rise is caused. , Due to fluctuations in the heat exchange situation due to contamination of the heat transfer surface of the reactor and other sudden factors from the outside,
It is also a feature of the present invention that by stopping the addition of aldehydes or adjusting the rate of addition, it is possible to immediately ensure safety and stabilize production even in reactions at high temperatures.

The aldehydes may be added from the upper part of the general reactor or the phenols at the liquid level. However, there are problems such as odor in the pressure reduction step, yield, and stability of the obtained molecular weight. Addition from the lower part of the reactor, which is excellent in terms of aspect, is preferred. Aldehydes injected from the lower part of the reactor react immediately and at the same time, partially complete the addition condensation reaction until they evaporate from the upper part of the reaction liquid, whereas addition from the upper part causes high temperature. This is because formaldehyde having a low vapor pressure may be vaporized on the liquid surface of the phenols in the state, and may remain in the gas phase of the reactor and may not react.

The reactor used in the present invention is a general pressure reactor. Two-stage turbine-type stirring blades (preferably having the same diameter) which are installed at the top and bottom, which are advantageous for adding aldehydes to the lower part of the reactor, are used. It is more preferable to have.

Aldehydes added from the lower part of the reactor react immediately, but partly evaporate and rise in the liquid. At this time, two stages of turbine type stirring blades, preferably two
By using a stage, the respective stirring flows collide at an intermediate position of the upper and lower turbine type stirring blades and a stagnation zone is formed, thereby preventing the rise of vaporized aldehyde and promoting the reaction,
The yield is improved, the amount of aldehyde gas in the gaseous phase is reduced, and this is also suitable for odor problems. On the other hand, in the case of a single-stage turbine blade or other large-scale stirring blades that produce upstream and downstream, the reaction efficiency of aldehydes is poor, a predetermined molecular weight cannot be obtained, and the yield decreases.

[0016] In this way, the product obtained by the addition condensation reaction of the phenol with the aldehyde added thereto is kept under pressure for several minutes after the addition of the aldehyde, and then flashed while reducing the pressure via a heat exchanger attached to the reactor. Dehydrate or
Dehydration is carried out while being transferred to a flash tank, and if necessary, unreacted monomers are removed by heating under reduced pressure or using a known thin-film evaporator to obtain a high ortho-type novolak phenolic resin containing extremely few ionic impurities.

Further, an example of the present invention will be described with reference to FIG. 1, but the present invention is not limited by the description. FIG. 1 is a schematic view showing the equipment and flow of the present invention, wherein (a) is a front view and (b) is a plan view. Phenols are put into a high-pressure reactor (2) equipped with upper and lower two-stage turbine-type stirring blades (1), and then heated to 160 ° C. or more, and an inert gas such as nitrogen gas is supplied to a pressure line (3). To 0.5 MPa or more. After reaching the predetermined temperature and pressure, the amount of aldehyde necessary to obtain the target molecular weight is injected and added from the injection nozzle (5) at the lower part of the reactor by the high-pressure metering pump (4).

While the injected aldehyde rises to the liquid level, the addition condensation reaction is completed with the phenol kept at a reaction temperature of 160 ° C. or higher. After completion of the reaction, the pressure regulating valve (6) is gradually opened to evaporate the water and the condensed water in the raw material, condensing the water in the heat exchanger (7) and removing the water out of the reaction system, and reducing the pressure in the reactor to normal pressure. To lower. Only the dehydrated resin remains in the reactor. Thereafter, the inside of the reactor is further reduced in pressure and further heated to remove unreacted monomers, taken out of the reactor, and cooled and solidified to obtain a high ortho-type novolak phenol resin having very few solid ionic impurities.

[0019]

The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited by these examples. It should be noted that all “%” described in the text indicate “% by weight”.

Example 1 22.0 kg of phenol was heated to 180 ° C. in a high-pressure reactor having a capacity of 50 L having a heat exchanger, a heating device and a two-stage turbine type stirring blade of the same diameter,
After pressurizing to 0.7 MPa with nitrogen gas, 40% formalin 1 whose formic acid content was reduced to 50 PPM by ion exchange resin treatment in advance with a diaphragm type high pressure metering pump.
0.5 kg was added sequentially from the lower part of the reactor over 60 minutes to cause an addition condensation reaction. During this time, the reaction temperature is 180-2
The temperature of the jacket of the reactor and the rate of addition were adjusted so as to be 00 ° C. After the reaction, 5
The dehydration reaction was performed while returning to normal pressure over a period of minutes. Thereafter, the pressure was reduced to 1.3 KPa, and the reaction solution was heated until the temperature of the reaction solution reached 180 ° C. to remove unreacted phenol. Then, the reaction solution was taken out on a cooling vat to obtain 21.0 kg of a solid novolak phenol resin. The time required from the start of the addition condensation to the end of the dehydration was 65 minutes.

Example 2 22.0 Kg of phenol, initial heating temperature of 160 ° C., initial pressure of 0.5 MPa, 40%
Example 1 except that the amount of formalin added was 13.5 kg.
The reaction was carried out in the same manner as described above to obtain 23 kg of a solid novolak type phenol resin.

<< Example 3 >> m-cresol / p-cresol mixture (60:40) 30.0 as phenols
28 kg of solid novolak type phenol resin was obtained in the same manner as in Example 1 except that Kg was used and the amount of 40% formalin was changed to 11.9 kg.

Example 4 Phenol 20.
Add 0 kg, and use 6.1 kg of 88% paraformaldehyde as aldehydes. Further, paraformaldehyde was previously mixed with 8.0 kg of phenol, and a suspension was obtained using a plunger-type high-pressure metering pump. Except for feeding from the lower part of the reactor, 27.0 kg of novolak type phenol resin was obtained in the same manner as in Example 2.

Example 5 28.0 kg of a novolak phenol resin was obtained in the same manner as in Example 4 except that 8.8 kg of 88% paraformaldehyde was used.

Example 6 20.0 kg of m / p-cresol as a phenol was placed in a reactor, and 7.3 kg of 88% paraformaldehyde and 10.0 kg of m / p-cresol were added.
A novolak-type phenol resin (30.0 kg) was obtained in the same manner as in Example 2 except that a mixture of cresol was supplied from the lower part of the reactor.

Example 7 The procedure of Example 1 was repeated, except that 40% formalin was added to the liquid surface from the upper part of the reactor, to obtain 18.0 kg of a novolak-type phenol resin.

Example 8 The same procedure as in Example 1 was carried out except that a general 40% formalin having a formic acid concentration of 400 PPM was used, to obtain 22.0 kg of a novolak-type phenol resin.

Comparative Example 1 22.0 kg of phenol and 0.22 kg of oxalic acid, which is a typical novolak catalyst, were put into the reactor used in Example 1 and heated to 100 ° C. under normal pressure, and then 40% After gradually adding 10.5 kg of formalin for 90 minutes, the reaction was continued at 60 ° C. for 60 minutes. Further, the resin was dehydrated while being heated at a normal temperature to 130 ° C., and then the pressure was reduced to 1.3 KPa, and unreacted phenol was removed until the temperature of the reaction solution reached 180 ° C. Then, it was taken out into a cooling vat to obtain 21.0 kg of a novolak type phenol resin. The time required from the start of the addition condensation reaction to the end of the dehydration was 4 hours and 30 minutes.

Comparative Example 2 The amount of 40% formalin was changed to 1
A novolak-type phenol resin (23.0 kg) was obtained in the same manner as in Comparative Example 1 except that the amount was 4.7 kg.

Comparative Example 3 Into the reactor used in Example 1, 22.0 kg of phenol, 4.8 kg of 88% paraformaldehyde, and 0.22 kg of zinc acetate, a representative of a divalent metal salt, as a high orthonovolacation catalyst were placed. Then, the mixture was heated to 100 ° C. under normal pressure, kept at 100 ° C., and the reaction was continued for 3 hours. Thereafter, the mixture was cooled to 90 ° C. and mixed with 0.11 kg of oxalic acid and 0.33 kg of water as a condensation reaction promoting catalyst. The mixture was added, mixed for 30 minutes, heated to 100 ° C. again, and reacted for 1 hour. Further, after dehydration at normal pressure to 130 ° C., the pressure was reduced to 1.3 KPa, and the temperature of the reaction solution was 1
Unreacted phenol was removed until the temperature reached 80 ° C., taken out into a cooling vat, and 20.0 kg of a novolak type phenol resin was obtained. The time required from the start of the addition condensation to the end of the dehydration was 7 hours.

Comparative Example 4 The reactor used in Example 1 was charged with 15.0 kg of phenol, 4.8 K of 88% paraformaldehyde and 15.0 kg of xylene. The reactor was sealed and heated to 150 ° C. The reaction was carried out for 2 hours while maintaining the temperature of ° C. When this liquid was cooled and analyzed, it was found that the weight-average molecular weight was about 150, which was almost unreacted.

<Comparative Example 5> After completion of the addition condensation reaction by reacting for 20 hours in the same manner as in Comparative Example 6, the reactor was cooled until the pressure in the reactor became atmospheric pressure, and heated until the pressure in the reactor became 150 ° C. Dehydration and xylene removal were performed. Further 1.33 KPa
Unreacted phenol is removed until the temperature of the reaction solution reaches 180 ° C., taken out to a cooling vat, and 13.0 K
g of novolak type phenol resin was obtained. The time required from the start of the addition condensation to the end of the dehydration was 24 hours.

Comparative Example 6 The reaction was performed in the same manner as in Example 1 except that the initial pressurization with nitrogen gas was not performed. As a result, the temperature of the reaction solution was lowered from the start of formalin addition, and the predetermined reaction solution temperature could not be maintained. The procedure was continued as it was to obtain 16.0 kg of a novolak type phenol resin, but the yield was very poor as compared with the examples.

The properties of the resin obtained in each of the above examples were measured, and the results are shown in Table 1.

[Table 1]

The measuring method is as follows. 1. The weight average molecular weight was measured by a gel permission chromatography (GPC) method using an ultraviolet absorption spectrum detector using polystyrene as a standard substance. As for Comparative Example 5, the measurement was made on the tetrahydrofuran-soluble portion. 2. The monomer content was measured by a capillary gas chromatography method. Comparative Example 5 was a measurement of a methanol-soluble portion. 3. The ortho / para bond ratio was calculated by substituting the methylene group bond amount determined by ¹³ C-NMR spectroscopy after dissolution in tetrahydrofuran into the following equation. In Comparative Example 5, the measurement of the tetrahydrofuran-soluble portion was performed. Ortho / para bond ratio = [2 × (oo bond) + (op
Bond)] / [2 × (pp bond) + (op bond)] oo bond: number of ortho-ortho-bond methylene groups op bond: number of ortho-para bond methylene groups p 3. -p bond: the number of methylene groups bonded in the para-para position. The curing time was determined by mixing and pulverizing and mixing 10% of hexamethylenetetramine with the obtained solid resin.
Based on IS K 6909, the time to the gel point on a hot plate at 150 ° C. was measured. 5. The extracted water electric conductivity is an item for grasping the ionic impurities in the resin, and the smaller the numerical value, the smaller the ionic impurities. This time 6g of solid resin and 40 of pure water
ml was placed in a pressure cooker container, sealed, and heat-treated in a thermostat at 125 ° C. for 20 hours. The extracted water was measured for electric conductivity using an electric conductivity meter (CM-2A, manufactured by Toa Denpa Kogyo Co., Ltd.).

As is clear from these measured values, the novolak-type phenolic resin produced in the examples of the present invention has more ortho-methylene bonds than para-methylene bonds (ortho / para bond ratio> 2. 0) It is a high-ortho novolak, the curing speed of which is higher than that of the novolak comparative examples 1 and 2 using a general acid catalyst, and less ionic impurities. In addition, not only the addition condensation reaction and the dehydration reaction can be completed in a short time, but also the yield per reactor volume can be increased as compared with other methods for producing a high-ortho novolak.

[0037]

According to the method of the present invention, it is possible to efficiently produce a high-ortho novolac having a small amount of ionic impurities and excellent curability, which have not been simultaneously realized conventionally. That is, it is easy to control the reaction pressure during the high-temperature reaction, so that safety is sufficiently ensured, and a high yield can be obtained in a short-time reaction. And since the cured product is excellent in heat resistance, electrical insulation, and moisture resistance, it can be applied to a wide range of applications including electric and electronic fields, and is suitable as an industrial method for producing a novolak type phenol resin. is there.

[Brief description of the drawings]

FIG. 1 is a schematic view of the equipment of the present invention, wherein (a) is a longitudinal sectional view and (b) is a transverse sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Turbine-type stirring blade 2 High-pressure reactor 3 Nitrogen gas filling line 4 Aldehydes high-pressure metering pump 5 Aldehydes injection nozzle 6 Pressure control valve 7 Heat exchanger

Claims (5)

[Claims] 1. When reacting a phenol with an aldehyde without using a catalyst, the phenol is previously reacted with 1
After heating to 60 ° C or more, 0.5MP with inert gas
A method for producing a novolak-type phenol resin, characterized in that an addition condensation reaction is carried out while maintaining the reaction temperature at 160 ° C. or higher by pressurizing the mixture to a pressure of not less than a. 2. The method according to claim 1, wherein the aldehyde is added from a lower part of the reactor. 3. As a aldehyde, formic acid is 200 PP.
The method for producing a novolak-type phenol resin according to claim 1 or 2, wherein formalin removed to M or less is used. 4. The method for producing a novolak-type phenolic resin according to claim 1, wherein paraformaldehyde having a purity of 80% or more is used as the aldehyde, and this is dissolved or suspended in a phenol. 5. The method for producing a novolak-type phenolic resin according to claim 1, wherein the reactor has a two-stage turbine-type stirring blade.