JP2887300B2 - Method for producing high-grade bisphenol A - Google Patents

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 high-quality bisphenol A having excellent color and high purity. Bisphenol A is a raw material for polycarbonate resins and epoxy resins. In recent years, the demand for colorless, transparent and high-purity bisphenol A particularly suitable for optical applications has been remarkably increased.

[0002]

BACKGROUND OF THE INVENTION Bisphenol A [2.2
-Bis (4-hydroxyphenyl) propane] is known to react excess phenol with acetone in the presence of an acid catalyst. Further, in order to separate and recover high-purity bisphenol A from the reaction product, the reaction product was cooled to crystallize a crystal adduct of bisphenol A and phenol (hereinafter, also simply referred to as a crystal adduct). It is also known to remove phenol from adduct crystals (JP-B-52-42790).
No.) In such a method for producing bisphenol A, the hue of bisphenol A recovered as a product is:
Of course, the hue of bisphenol A obtained greatly depends on the conditions for separating and removing phenol from the crystal adduct, of course, depending largely on the hue of the crystal adduct itself. A heating method for heating and melting a crystal adduct and evaporating and removing phenol from the melt (for example,
In JP-B-52-42790, the hue of bisphenol A obtained deteriorates due to the heating. A
Even with a crystalline adduct having a good hue of PHA 15 or less, the color of the product bisphenol A obtained by heating and melting this and then removing phenol by evaporation is deteriorated,
Usually, it will show an APHA of 40 or more.

[0003]

An object of the present invention is to provide a method for separating and recovering high-purity bisphenol A from a crystalline adduct of bisphenol A and phenol having a good hue without deteriorating the hue. Make it an issue.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, a crystalline adduct consisting of bisphenol A and phenol under an APHA of 15 or less under a substantially neutral condition is treated with an oxygen concentration of 0.000 in the atmosphere.
A method for producing high-grade bisphenol A, characterized in that it is heated and melted under a condition of 5 vol% or less and phenol is removed by evaporation from the obtained melt.

[0005] The crystalline adduct of bisphenol A and phenol used in the present invention is produced by a conventionally known method. That is, an excess phenol and acetone are reacted in the presence of an acid catalyst to obtain a reaction product containing bisphenol A, and the reaction product is subjected to a crystallization treatment to obtain a crystal adduct of bisphenol A and phenol. Can be obtained.

In the reaction of phenol with acetone to obtain bisphenol A, hydrochloric acid,
Acidic substances such as sulfuric acid and sulfonic acid type strong ion exchange resins are used. In the reaction system of phenol and acetone, such an acidic substance not only acts as a catalyst for the reaction, but also exhibits an action of promoting the generation of coloring substances and impurities under heating conditions. Reduces hue and purity. Therefore, it is necessary to remove such acidic substances after the reaction so as not to flow to the subsequent dephenolization step involving heating conditions. For example, in a reaction using hydrochloric acid as a catalyst, a method has been proposed in which, after the reaction, the product is heated to remove hydrochloric acid, and the remaining hydrochloric acid is alkali-neutralized to pH 5 to 6 (particularly). No. 47-43937). In the method using a strong acid-type ion exchange resin, the organic sulfonic acid is desorbed by the decomposition of the ion exchange resin during the reaction,
A method has been proposed in which the organic sulfonic acid is neutralized using a weakly basic ion exchange resin because it is mixed in the product (US Pat. No. 4,191,843). On the other hand, the hue and purity of phenol and bisphenol A decrease not only with an acid but also with an alkali. Therefore, it is necessary to neutralize an acidic substance with an alkali not to exceed the neutralization point. As described above, in the reaction in which phenol and acetone are reacted in the presence of an acidic substance, the acidic substance present in the reaction product is neutralized after the reaction so as not to exceed the neutralization point, or removed from the reaction system. When there is an alkali used for neutralizing the acidic substance, it is necessary to remove the alkali. Also,
The removal of acidic substances or alkali present in the reaction product can be removed by using a multi-stage crystallization step in a subsequent crystallization step. The crystal adduct under a substantially neutral condition used in the present invention means a crystal adduct from which the influence of an acidic substance or an alkaline substance has been removed. Such a crystalline adduct is added and dissolved in an aqueous methanol solution adjusted to an acidity of pH 5.0 to give a pH of 4.90 to 5.5 in a pH measurement method under substantially non-ionization conditions of phenol.
0, preferably a pH of 4.95 to 5.20. The pH of the crystal adduct shown in this specification
Is obtained by the above-mentioned measuring method. In the present invention, as described above, a crystal adduct that is substantially under neutral conditions and has a melt color APHA of 15 or less is used. A crystalline adduct with a melt color APHA of 15 or less is
It can be obtained by maintaining the crystalline adduct under substantially neutral conditions as described above, but if necessary, by increasing the number of crystallization stages in the crystallization step, or by using an organic solvent such as phenol or toluene. Crystallization washing in the coexistence of
A can be further improved.

In the present invention, this crystalline adduct is heated and melted, and phenol is removed from the obtained melt by evaporation.
At this time, the oxygen concentration in the heating atmosphere in the heat melting step and the step of evaporating and removing phenol from the melt is adjusted to 0.005 vol% or less, preferably 0.001 v
ol% or less. The temperature at which the crystal adduct is heated and melted is 115 to 180 ° C., preferably 120 to 180 ° C.
50 ° C. and the pressure is 1.0 to
It is 5.0 atm, preferably 1.0 to 1.9 atm. The heating and melting of the crystal adduct can be performed using an external heating type heating vessel. Evaporation and removal of phenol from the melt of the crystal adduct can be performed using a distillation column or a thin film evaporator. In this case, the evaporator can be multi-stage, but the heating temperature of the final stage is 160-200 ° C.
The temperature is preferably 170 to 185 ° C., and the pressure is set under reduced pressure.
A pressure of 0 Torr is employed. In this phenol evaporation removal, most of the phenol is distilled off using a thin film evaporator or the like, and then a small amount of the remaining phenol is removed by steam stripping. In this case, the supply amount of steam was 1 weight ratio with respect to bisphenol A.
/ 50 to 1/5, preferably 1/25 to 1/10.

[0008]

The product bisphenol A obtained as described above has a purity of 99.95% by weight or more and has excellent color, and usually has a color of APHA 20 or less. Such high-grade bisphenol A is
It is suitable as a raw material bisphenol A for high-grade polycarbonate and epoxy resin, and is also suitable as bisphenol A for applications where a colorless and transparent material is used in the optical field.

[0009]

Next, the present invention will be described in more detail with reference to examples.

Example 1 A mixture of bisphenol A, phenol and impurities obtained by reacting phenol and acetone in the presence of an acid catalyst is subjected to a multi-stage crystallization step, whereby
A crystalline adduct of melt color APHA5, pH 5.05 was obtained. Next, this crystal adduct was subjected to a temperature of 130 ° C., a pressure (absolute pressure) of 1.20 atm, and an oxygen concentration in the atmosphere of 0.1 atm.
Under the condition of 0010 vol%, the mixture was heated and melted using an externally heated closed heating vessel, and the obtained melt was transferred to a closed evaporator by piping. The melt temperature was 180 ° C and the oxygen concentration in the atmosphere was 0. Evaporation under the condition of 0.001% by volume,
Next, steam was introduced and stripping was performed at a temperature of 180 ° C. under the condition of an oxygen concentration of 0.0030 wt% in the atmosphere. Bisphenol A thus obtained has a purity of 9
9.96% by weight or more, free phenol content 30wt
ppm or less, which was a high-grade product showing the hue of the molten color APHA20.

Comparative Example 1 An experiment was carried out in the same manner as in Example 1 except that the oxygen concentration in the atmosphere in the heating and melting step of the crystal adduct and the evaporation and stripping treatment of the melt was changed to 0.006 vol%. In this case, the obtained bisphenol A shows a molten color APHA65 and a purity of 99.96.
% By weight and a free phenol content of 30 wtppm or less.

Comparative Example 2 In Example 1, a separately prepared melt-colored APHA10 was prepared.
An experiment was conducted in the same manner except that a crystal adduct of pH 4.85 was used. In this case, the obtained bisphenol A had a molten color APHA40, a purity of 99.90% by weight or more, and a free phenol content of 50 ppm or less.

Comparative Example 3 In Example 1, a melt-colored APHA20 prepared separately was used.
The experiment was performed in the same manner except that an adduct of pH 5.05 was used. The obtained bisphenol A is a molten color APH
A45, having a purity of 99.96% by weight or more and a free phenol content of 30% by weight or less.

Example 2 An experiment was conducted in the same manner as in Example 1, except that the oxygen concentration in the atmosphere was varied in the heating and melting step of the crystal adduct and the evaporation of the melt. Table 1 shows the results. In addition, BPA in Table 1 shows bisphenol A. Experiment No. 6 shows a comparative example.

[0015]

[Table 1]

Continued on the front page (72) Inventor Sachio Asaoka 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Kako Construction Co., Ltd. (72) Ryuichi Inaba 2--12, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa No. 1 Inside Chiyoda Kako Construction Co., Ltd. (56) References JP-B-52-42790 (JP, B2) JP-B-57-57012 (JP, B2) JP-B-47-43937 (JP, B1) (58) Survey Field (Int.Cl. ⁶ , DB name) C07C 39/16 C07C 37/68-37/88

Claims (1)

(57) [Claims] 1. A crystalline adduct composed of bisphenol A and phenol, which is in a substantially neutral condition having a molten color APHA of 15 or less, is heated and melted under an atmosphere having an oxygen concentration of 0.005 vol% or less, and the obtained melt is melted. A process for producing high-quality bisphenol A, comprising removing phenol from a product by evaporation.