JPH07291879A - Method for crystallizing adduct of bisphenol a and phenol - Google Patents

Abstract

PURPOSE:To provide a crystallizing method capable of obtaining crystals of adduct of bisphenol A to phenol having large particle diameter and narrow particle diameter distribution. CONSTITUTION:A phenol solution of bisphenol A is cooled to a range of 40 deg.C to 75 deg.C to crystallize adduct of bisphenol A to phenol. The resultant crystals have wide particle diameter distribution. The temperature of the contents is raised by 1-20 deg.C to dissolve fine crystals and then the temperature of the contents is cooled to 35 deg.C to 70 deg.C to provided crystals of adduct of bisphenol A to phenol.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of crystallizing adduct crystals of bisphenol A and phenol. More specifically, when crystallizing an adduct crystal of bisphenol A and phenol by cooling, the temperature of the content is raised during cooling, and then the temperature of the content is lowered to increase the particle size,
The present invention relates to a method for obtaining an adduct of bisphenol A and phenol having a narrow particle size distribution. Demand for bisphenol A as a raw material for engineering plastics in addition to polycarbonate resins and epoxy resins has been increasing in recent years.

[0002]

2. Description of the Related Art One of the methods for producing bisphenol A is
Reacting phenol and acetone in the presence of an acid catalyst,
Bisphenol A was crystallized as an adduct with phenol by cooling the liquid mixture remaining after removing the catalyst, water and a small amount of phenol from the reaction mixture,
There is a method in which the crystals are separated from the mother liquor and phenol is removed from the adduct to recover bisphenol A.

As a method of crystallizing an adduct of bisphenol A and phenol, as disclosed in JP-A-58-135832, water is added and the heat of vaporization removes heat such as crystallization heat. There is a way to do. However, nothing is mentioned about the method of controlling the grain size and grain size distribution of the precipitated crystals.

One of the problems in crystallization is that secondary industrial nucleation is intense in normal industrial operation and the particle size distribution is widened. When the particle size is small and the particle size distribution is wide, separation from the mother liquor is difficult and stable crystals cannot be produced, which causes deterioration and variations in quality due to mother liquor adhesion.

As a crystallizer devised to control the grain size distribution in crystallization, the Chemical Engineering Handbook (Revised 5th Edition, P. 44)
4-P. 446), in which microcrystals are suspended and a part is dissolved by a feed liquid, a crystal-Oslo type, a cross-sectional area of a tank is made smaller as it goes downward, and a conical type for classifying crystals is grown here. There are a DTB type in which the formed crystal is extracted from the middle of the classifying leg, and a distributor type in which a primary crystal and a secondary crystal are formed in the tank to form a fluidized bed of coarse crystals.

However, these devices are expensive to manufacture, cannot be classified in a system having a small settling speed of crystals, and uniform crystals cannot be obtained. Since the slurry is forcedly circulated, coarse particles are severely crushed. There are drawbacks such that the width of the diameter distribution becomes wider and the classification effect is reduced.

[0007]

The object of the present invention is to provide a bisphenol A and a phenol having a large particle size and a narrow particle size distribution, which do not have the above-mentioned problems when crystallizing an adduct of bisphenol A and phenol by cooling. The object of the present invention is to provide a method capable of obtaining adduct crystals of

[0008]

Means for Solving the Problems The inventors of the present invention have made extensive studies in order to achieve the purpose of the first half, and when the crystallization of the adduct crystal of bisphenol A and phenol is carried out by cooling, the temperature is raised during cooling, Then, it was found that the object of the present invention was achieved by lowering the temperature, and the present invention was completed.

That is, according to the present invention, in the method of cooling and crystallization of an adduct of bisphenol A and phenol from a phenol solution of bisphenol A, the temperature of the contents is raised during cooling to 35 ° C. to 70 ° C., and then cooling is performed. It is a method for crystallizing an adduct crystal of bisphenol A and phenol characterized by restarting.

In the present invention, the phenol solution of bisphenol A supplied to the crystallizer is prepared by reacting phenol and acetone in the presence of an acid catalyst to remove the catalyst, water and a small amount of phenol from the reaction mixture. The remaining liquid mixture may be used, or crude bisphenol A containing 2- (2-hydroxyphenyl) -2- (4-hydroxyphenyl) propane, dianine compound, trisphenol, polyphenol, etc. may be dissolved in phenol. It may be one.

In the reaction of phenol with acetone, usually, an excess amount of phenol of 4 to 12 times with respect to acetone is used, and the reaction is performed substantially without using a solvent as the third component.

This reaction is usually carried out at a temperature of 30 to 120 ° C., preferably 40 to 100 ° C. under a pressure of atmospheric pressure to 5 kg / cm ² . If the reaction temperature is too low, the reaction rate is slow, and if it is too high, the amount of by-products is increased, which is not preferable.

The reaction time varies depending on the reaction type, especially the reaction temperature, but is usually 0.1 to 10 hours in the case of batch reaction using a stirred tank, and is empty in the case of continuous reaction with a fixed catalyst bed. The tower speed is adjusted to 0.1 to 10 / hour. Examples of acid catalysts include hydrochloric acid and strongly acidic ion exchange resins. Further, a promoter such as a sulfur compound may be added.

The operation method includes batch operation, semi-batch operation,
Alternatively, either continuous operation may be used. In the batchwise method, a phenol solution of bisphenol A is charged into a crystallizer and cooled with gentle stirring to crystallize an adduct crystal of bisphenol A and phenol. Raise the temperature of the contents in the range of 75 ° C and then cool the contents to the range of 35-70 ° C.

In the continuous method, three crystallizers are used and the bisphenol A phenol solution is cooled while flowing in series to crystallize adduct crystals of bisphenol A and phenol. During this cooling crystallization, the temperature of the first crystallizer was lowered to the range of 40 to 75 ° C., the temperature of the contents was increased by the second crystallizer, and the temperature of the third crystallizer was increased. Cool to the range 35-70 ° C.

In any of the batch operation, the semi-batch operation and the continuous operation, the temperature rise is usually 1 to 20 ° C. The cooling is performed by removing heat by evaporating water and a small amount of phenol added to the crystallizer.

The distillate obtained by evaporation consists of water and a small amount of phenol and can be recycled and recycled. The amount of water added is sufficient for cooling the phenol solution of bisphenol A and for removing the heat of crystallization generated during the formation of adduct crystals by evaporation. This corresponds to 2 to 20% by weight of the phenol solution.

The crystallizer operates under constant pressure and the temperature of the contents is controlled by the amount of water added to the crystallizer. The operating pressure is preferably 20 to 100 mmHgabs.

As a method of raising the temperature of the contents during cooling crystallization and then cooling, for example, a crystallizer with a jacket is used, and hot water or steam whose temperature is controlled is passed through the jacket. . Alternatively, the temperature of the contents may be raised by an ordinary heat exchanger.

[0020]

EXAMPLES The method of the present invention will be described in detail below with reference to examples. In the following Examples and Comparative Examples, the smaller the ratio of 25% particle size on the sieve to the 75% particle size, the narrower the particle size distribution, and the larger the ratio, the wider the particle size distribution. Example 1 140 kg of phenol and 14 kg of acetone were mixed, and a condensation reaction was carried out at 55 ° C. for 8 hours while blowing hydrogen chloride into the mixture. The reaction mixture was placed under a vacuum of 43 mm Hgabs for 12 hours.
The mixture was heated to 5 ° C. to remove hydrochloric acid and water generated by the reaction. The composition of this dehydrochloric acid solution was 35% by weight of bisphenol A, 63% by weight of phenol, and 2% by weight of by-product.
100 kg of this phenol solution and 10 kg of water were charged into a crystallizer. The temperature of the content of the crystallizer immediately after charging is 100 ° C.
Met. Use a crystallizer with a jacket, 50
The pressure was reduced to mmHgabs, and warm water of 51 ° C. was run through the jacket for 2 hours. The temperature of the contents of the crystallizer became constant at 50 ° C. Next, steam was flowed through the jacket for 30 minutes to raise the temperature of the contents to 60 ° C., and then cooling water was flowed through the jacket for 40 minutes. The temperature of the contents became constant at 45 ° C. The whole amount of the slurry was extracted and filtered. The average particle size of the obtained adduct of bisphenol A and phenol is 0.5.
The ratio of the 25% particle size to the 75% particle size on a 7 mm, JIS standard sieve was 1.4.

Example 2 140 kg of phenol and 14 kg of acetone were mixed, and a condensation reaction was carried out at 55 ° C. for 8 hours while blowing hydrogen chloride into the mixture. The reaction mixture was placed under a vacuum of 43 mm Hgabs for 12 hours.
The mixture was heated to 5 ° C. to remove hydrochloric acid and water generated by the reaction. The composition of this dehydrochloric acid solution was 35% by weight of bisphenol A, 63% by weight of phenol, and 2% by weight of by-product.
This phenol solution is used at 90 ° C and a flow rate of 40 kg / hr for 5 times.
It was fed to a crystallizer operating at 0 mm Hgabs. As the crystallizer, three tanks with jackets were used, and warm water of 52 ° C., 62 ° C., and 47 ° C. was poured into the jackets, respectively. Water was added to the first tank from another route at a flow rate of 4 kg / Hr. The temperature of the contents of the crystallizer is 50 ° C in the first tank and 60 in the second tank.
C. and the third tank became constant at 45.degree. Continuously withdraw the slurry from the third tank to keep the liquid level of the crystallizer constant.
It was filtered continuously. The average particle size of the obtained bisphenol A / phenol adduct was 0.55 mm, and the ratio of the 25% particle size to the 75% particle size on the JIS standard sieve was 1.5.

Comparative Example 1 In the same manner as in Example 1, a phenol solution of bisphenol A was prepared. The composition of the phenol solution was the same as described in Example 1. This phenol solution 10
A crystallizer was charged with 0 kg and 10 kg of water. Use a jacketed crystallizer and reduce the pressure to 50 mmHgabs.
Warm water at 46 ° C. was flowed through the jacket for 2 hours and 30 minutes. The temperature of the contents of the crystallizer remained constant at 45 ° C. The whole amount of the slurry was extracted and filtered. Obtained bisphenol A
The average particle size of the adduct of phenol and phenol is 0.35 mm, JI
The ratio of the 25% particle size and the 75% particle size on the S sieve was 3.0.

Comparative Example 2 A phenol solution of bisphenol A was prepared in the same manner as in Example 2. The composition of the phenol solution was the same as that described in Example 2. 9 parts of this phenol solution
It was fed to a crystallizer operating at 50 mm Hgabs at 0 ° C. and a flow rate of 40 kg / Hr. Two crystallizers with jackets were used, and warm water of 52 ° C. and 47 ° C. was poured into the jackets. 4 kg / Hr of water from another route to the first tank
Was added at a flow rate of. The temperature of the contents of the crystallization tank is 5 in the first tank.
It became constant at 0 ° C and 45 ° C in the second tank. The slurry was continuously withdrawn from the second tank so as to keep the liquid level of the crystallizer constant, and continuously filtered. The average particle size of the resulting adduct of bisphenol A and phenol was 0.41 mm, and the ratio of 25% particle size to 75% particle size on the JIS standard sieve was 3.1.

[0024]

According to the present invention, when the adduct of bisphenol A and phenol is crystallized from the phenol solution of bisphenol A, a stable operation can be performed, and an adduct having a large particle size and a uniform size can be obtained. You can get it. Therefore, the work is facilitated in the filtration and washing process after the crystallization process, and the crystal recovery rate is expected to be improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisaho Hinohara Mitsui Toatsu Chemical Co., Ltd. 2-1, Tango-dori, Minami-ku, Nagoya-shi, Aichi

Claims (3)

[Claims] 1. A method of cooling and crystallizing an adduct of bisphenol A and phenol from a phenol solution of bisphenol A, while cooling to 35 ° C. to 70 ° C.
A method for crystallizing adduct crystals of bisphenol A and phenol, which comprises raising the temperature of the contents and then restarting the cooling. 2. The temperature of the contents is 1 to 20 ° C. during cooling.
The crystallization method according to claim 1, wherein the crystallization method is carried out. 3. The temperature of the contents when raising the temperature is 40
C.-75.degree. C. The crystallization method according to claim 1, characterized in that the temperature is 75.degree.