JPH06107579A - Method for producing bisphenol A - Google Patents

Abstract

(57) [Summary] [Purpose] Using a centrifugal thin film evaporator, bisphenol A
Provided is a method for producing bisphenol A, which is capable of stably producing high-purity bisphenol A for a long period of time by evaporating and removing phenol from an adduct or a mixture of phenol and phenol. [Composition] Addition or mixture of bisphenol A and phenol was charged into a centrifugal thin film evaporator, and bisphenol A was added.
When separating and recovering the bisphenol A, the adduct or mixture of bisphenol A and phenol is charged into a flash evaporator to adjust the phenol content to 4% by weight or less, and then charged into a centrifugal thin film evaporator to separate the bisphenol A. It is a method for producing bisphenol A to be recovered.

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 bisphenol A, and more particularly to a method for producing high-purity bisphenol A by removing phenol from an adduct or mixture of bisphenol A and phenol.

[0002]

BACKGROUND OF THE INVENTION Bisphenol A, 2,2-bis (4-hydroxyphenyl) propane, is a compound that is solid at room temperature and is produced by reacting acetone with excess phenol in the presence of an acidic catalyst. ing.
The reaction mixture obtained by this reaction contains impurities such as a catalyst, unreacted phenol, unreacted acetone, reaction product water and other reaction by-products in addition to the target bisphenol A. Impurities need to be separated and removed. Then, as one of the methods for recovering bisphenol A from this reaction mixture, after removing the catalyst and water if necessary from the reaction mixture, the obtained liquid mixture is cooled to form crystals of an adduct of bisphenol A and phenol. There is a method of precipitating, separating and removing the mother liquor from the slurry containing the adduct crystals, and then dephenolizing the adduct crystals thus obtained to recover the target bisphenol A.

As the method for dephenolizing the adduct or mixture of bisphenol A and phenol to be carried out here, a vacuum distillation method or a steam stripping method (for example, JP-A-63-132,850 or JP-A-2- 28,126
), But relatively high-purity bisphenol A
Therefore, a method using a centrifugal thin film evaporator (Japanese Patent Laid-Open No. 3-95,135) has also been proposed.
This method using a centrifugal thin film evaporator is capable of minimizing the decomposition and coloration of bisphenol A without exposing the treated material to high temperature for a long time, and the hue of the obtained bisphenol A is excellent. However, on the other hand, there is a problem that crystals are precipitated during operation, and it is difficult for a centrifugal thin-film evaporator having a movable part inside the body to operate stably for a long period of time. Was issued.

[0004]

Therefore, as a result of studying the reason why the centrifugal thin film evaporator cannot be stably operated for a long period of time in this way, as a result, in the past, the residual phenol was reduced exclusively. Since the operation of this centrifugal thin film evaporator was performed under a high vacuum of 30 torr or less, when an additive or mixture containing 30% by weight or more of phenol was introduced into this centrifugal thin film evaporator. A large amount of this phenol evaporates in a short time, a large amount of latent heat of vaporization is taken away at that time, the temperature of the treatment liquid rapidly decreases, and crystals of bisphenol A precipitate due to the relationship between the residual phenol and the liquid temperature. We have found that this hinders the stable operation of the centrifugal thin film evaporator for a long period of time. Especially, when the precipitation of the bisphenol A crystals occurs in the charging part of the centrifugal thin film evaporator, the crystals adhere to the rotating part of the centrifugal thin film evaporator, the rotation becomes unbalanced, and the centrifugal thin film evaporator itself is Vibration or centrifugal force occurs and stable operation becomes impossible. Further, if this crystal precipitation occurs in the evaporation part of the centrifugal thin film evaporator, the crystal is caught between the rotor and the body of the centrifugal thin film evaporator, and abnormal force acts on the motor to make stable operation impossible. It will be possible.

As a method for solving this problem, the temperature at which the adduct or the mixture is charged into the centrifugal thin film evaporator is lowered so that bisphenol A is contained in the residual enol.
Although it can be considered that this method is effective, the precipitation of crystals in the charging part can be effectively suppressed by this method, but when the phenol evaporates in the evaporation part after that, the amount of residual phenol and the liquid temperature Because of this, crystals will precipitate. As another method, it is possible to prevent the precipitation of crystals by suppressing the rapid evaporation of phenol by lowering the degree of vacuum in the centrifugal thin film evaporator. The amount of residual phenol is increased to about 4% by weight, and in order to produce high-purity bisfunol A, it is necessary to provide a treatment step with a high-vacuum centrifugal thin-film evaporator in a subsequent stage.

As a result of intensive studies to solve such problems in the method using a centrifugal thin film evaporator, the present inventors have installed an additive or mixture of bisphenol A and phenol in the centrifugal thin film evaporator. It was found that the problems with the centrifugal thin-film evaporator described above can be solved by using a flash evaporator in advance to adjust the phenol content of the adduct or mixture to 4% by weight or less before entering. The present invention has been completed. Therefore, an object of the present invention is to use a centrifugal thin film evaporator to evaporate and remove phenol from an adduct or a mixture of bisphenol A and phenol, and to stably produce high-purity bisphenol A for a long period of time. It is to provide a manufacturing method of A.

[0007]

That is, according to the present invention, when an adduct or a mixture of bisphenol A and phenol is charged into a centrifugal thin film evaporator to separate and recover bisphenol A, the bisphenol A and the phenol are mixed with each other. Bisphenol A for charging the adduct or mixture to a flash evaporator to adjust the phenol content to 4% by weight or less, and then charging to a centrifugal thin film evaporator to separate and recover bisphenol A.
Is a manufacturing method.

In the present invention, the adduct of bisphenol A and phenol is a reaction mixture obtained by reacting acetone with excess phenol in the presence of an acidic catalyst,
After removing the low-boiling substance and the catalyst as necessary, the obtained liquid mixture is cooled to precipitate the adduct crystals of bisphenol A and phenol, and the mother liquor is extracted from the slurry containing the adduct crystals. It is obtained by removal, and is preferably one obtained by further recrystallizing with phenol or washing to remove most of the impurities. Regarding this adduct, in order to obtain high-purity bisphenol A,
It is desirable that the purity is as high as possible. The adduct or mixture of bisphenol A and phenol is
Usually, it contains about 30 to 40% by weight of phenol.

In the method of the present invention, such an adduct or mixture of bisphenol A and phenol is once charged into a flash evaporator and adjusted so that the phenol content is 4% by weight or less. For this phenol content,
There is no lower limit as long as it is 4% by weight or less, but the removal rate of phenol is far lower than that of the centrifugal thin film evaporator, so in this flash evaporator, keep it at about 2 to 4% by weight until the desired residual phenol concentration is reached. The removal of the phenol is preferably performed by the following centrifugal thin film evaporator. When the phenol content of the flash evaporator exceeds 4% by weight, it becomes difficult to stably perform the dephenoling operation by the centrifugal thin film evaporator for a long period of time. This flash evaporator is operated at a temperature of 160 ° C or higher and at an equilibrium pressure capable of maintaining residual phenol at 4% by weight or less, and preferably 220 ° C or lower in order to prevent thermal decomposition or coloring of bisphenol A. ,
More preferably, it is operated at a temperature of 195 ° C or lower.

The bisphenol A having a phenol content of 4% by weight or less thus obtained is then charged into a centrifugal thin film evaporator to separate and collect high-purity bisphenol A. This centrifugal thin film evaporator is maintained at a high vacuum with a degree of vacuum of 30 torr or less, preferably 15 torr or less, and is heated to about 170 to 220 ° C., preferably 170 to 195 ° C. by a jacket or the like so that residual phenol is 50 ppm or less. Will be removed until

An example of a flash evaporator and a centrifugal thin film evaporator used in the method of the present invention will now be described with reference to FIG. In FIG. 1, the flash evaporator 1 is a body 1
a, raw material charging line 1b, circulation pump 1c, heater 1d
And a vapor outlet line 1e, and the centrifugal thin film evaporator 2 includes a body 2a, a liquid charging line 2b, and a vapor outlet line 2c.
And a liquid outlet line 2d. Centrifugal thin film evaporator 2
Inside the body 2a, a rotary blade is provided so as to rotate close to the inner wall of the body 2a, and the vapor outlet lines 1e and 2c are connected to a vacuum system. If necessary, a plurality of containers 2 can be continuously provided.

[0012]

According to the method of the present invention, the phenol content is 30% by weight.
The above-mentioned adduct or mixture of bisphenol A and phenol is not directly charged into a centrifugal thin film evaporator operated under a high vacuum of 30 Torr or less, and a phenol content of 4
Since it is charged after adjusting to less than 5% by weight, a large amount of phenol evaporates in a short time in the centrifugal thin film evaporator, a large amount of latent heat of vaporization is taken away, and the temperature of the processing liquid drops rapidly. The bisphenol A crystals do not precipitate due to the relationship between the residual phenol and the liquid temperature, and the long-term stable operation of the centrifugal thin film evaporator is not hindered.

[0013]

EXAMPLES The method of the present invention will be specifically described below based on Examples and Comparative Examples.

Example 1 In a flash evaporator and a centrifugal thin film evaporator as shown in FIG. 1, an adduct or mixture of bisphenol A and phenol consisting of 70% by weight of bisphenol A and 30% by weight of phenol was preheated to 150 ° C. The raw material charging line 1b was charged into the body 1a of the flash evaporator 1 maintained at a temperature of 165 ° C. and a pressure of 50 torr. At this time, the flash evaporator 1 is discharged and the liquid charging line 2 of the centrifugal thin film evaporator 2 is discharged.
The phenol content in bisphenol A charged into the body 2a from b was 3.8% by weight. The centrifugal thin film evaporator 2 was heated to 200 ° C. by the steam circulating in the jacket (not shown) and kept at a pressure of 10 torr.

The flash evaporator 1 and the centrifugal thin film evaporator 2 were operated under such conditions, and bisphenol A having a phenol concentration of 35 ppm was recovered from the liquid outlet line 2d of the centrifugal thin film evaporator 2. Flash evaporator 1 under these conditions
The centrifugal thin film evaporator 2 was operated for 30 days, and during that period, abnormal phenomena such as vibration, generation of centrifugal force, and overload of the motor were not observed at all, and stable operation was possible.

Comparative Example 1 The holding pressure of the flash evaporator 1 was set to 70 Torr, and the flash evaporator 1 was discharged from the liquid charging line 2b of the centrifugal thin film evaporator 2 into the body 2a. The liquid outlet line 2 of the centrifugal thin film evaporator 2 was operated in the same manner as in Example 1 except that the phenol content was 5.1% by weight.
Bisphenol A was recovered from d. The phenol concentration of the obtained bisphenol A was 120 ppm, and vibration and centrifugal force occurred in the centrifugal thin film evaporator 2 on the 5th day, which made stable operation impossible.

COMPARATIVE EXAMPLE 2 The holding pressure of the flash evaporator 1 was set to 100 torr, and the bisphenol A charged in the body 2a from the liquid charging line 2b of the centrifugal thin film evaporator 2 after exiting the flash evaporator 1 was used.
The content of phenol was 10.0% by weight, and the operation was performed in the same manner as in Example 1 except that the holding pressure of the centrifugal thin film evaporator 2 was set to 60 Torr, and the bisphenol was discharged from the liquid outlet line 2d of the centrifugal thin film evaporator 2. A was collected. Under these conditions, the flash evaporator 1 and the centrifugal thin film evaporator 2 were operated for 30 days, during which no abnormal phenomena such as vibration, generation of centrifugal force, motor overload, etc. were observed. The phenol concentration was as high as 5,800 ppm and did not reach the target of 200 ppm or less.

[0018]

According to the present invention, a high-purity bisphenol A can be stably produced for a long time from an adduct or a mixture of bisphenol A and phenol by using a centrifugal thin film evaporator.

[Brief description of drawings]

FIG. 1 is a flowchart showing a flash evaporator and a centrifugal thin film evaporator according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flash evaporator, 1a ... Body, 1b ... Raw material charging line, 1c ... Circulation pump, 1d ... Heater, 1e ... Steam outlet line, 2 ... Centrifugal thin film evaporator, 2a ... Body, 2b ... Liquid charging line 2c ... Steam outlet line, 2d ... Liquid outlet line.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Suda 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa, Chiyoda Kakoh Construction Co., Ltd. (72) Fumihiko Uemura Tsurumi-chuo, Tsurumi-ku, Yokohama-shi, Kanagawa 2-12-1, Chiyoda Kakoh Construction Co., Ltd. (72) Inventor Takeshi Kazaki 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Chiyoda Kakoh Construction Co., Ltd. (72) Inventor Toshihiko Furukawa Fukuoka 2-14-301, Shirahagi-cho, Kokurakita-ku, Kitakyushu, Japan (72) Inventor, Yosei Koga 1-6-5, Sakuradai, Naka-city, Fukuoka Prefecture (72) Toshikazu Maruyama, 2-chome, Nakai-ku, Kitakyushu, Fukuoka Prefecture 3-201 (72) Inventor Fumiaki Egashira 2-3-21 Chiyo, Yawatanishi-ku, Kitakyushu, Fukuoka

Claims (1)

[Claims] 1. When the adduct or mixture of bisphenol A and phenol is charged into a centrifugal thin film evaporator to separate and recover bisphenol A, the adduct or mixture of bisphenol A and phenol is installed in a flash evaporator. A method for producing bisphenol A, which comprises charging and adjusting the phenol content to 4% by weight or less, and then charging into a centrifugal thin film evaporator to separate and recover bisphenol A.