JP2962441B2 - Method for producing bisphenol A with low coloring properties - 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 bisphenol A having high purity and low coloring property. 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 having low coloring properties, particularly suitable for optical applications, has been significantly increased.

[0002]

BACKGROUND OF THE INVENTION Bisphenol A [2.2
-Bis (4'-hydroxyphenyl) propane] is known to react acetone with excess phenol 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 crystalline adducts. In such a method for producing bisphenol A, the purity of bisphenol A recovered as a product depends not only on the removal rate of phenol from the crystal adduct, but also on the impurities other than phenol contained in the adduct crystal. Is also affected by Since the impurities not only include coloring substances but also include substances that are easily colored, bisphenol A with low purity may be colored or easily colored. A method of washing an adduct crystal with liquid phenol to remove impurities other than phenol contained in the crystal adduct is known (Japanese Patent Application Laid-Open No. 1-146839).
This known method is characterized in that phenol separated from a crystalline adduct is used as a liquid phenol for washing, thereby obtaining a product bisphenol A having a better hue than using industrial phenol. In this case, the phenol is separated from the crystalline adduct by evaporation, extraction, stripping with steam, or the like. As a method of removing phenol from a crystalline adduct by evaporation, specifically, as described in JP-B-52-42790, the crystalline adduct is heated at a temperature above 180 ° C. and under reduced pressure at a temperature of 0.1 to 0.1 ° C. For example, a method of vaporizing in 30 minutes and separating and condensing phenol to separate it from bisphenol A can be mentioned. However, such a method has the following problems and has not been satisfactory yet. (1) In the phenol separated by evaporation or steam stripping, there are impurities such as chroman and 2,4'-bisphenol A contained in the adduct itself, and coloring causes such as isopropenylphenol generated by heating in the separation step. Is mixed. This is particularly noticeable at high evaporation temperatures. When phenol mixed with these impurities is used for adduct washing, a bisphenol A product having high purity, good hue, and low coloring property cannot be obtained. (2) When the solvent extraction method is used, equipment and utility for separating the solvent and phenol are required. In addition, the solvent is mixed into the phenol separated by the solvent extraction, and the solvent is removed together with the washed phenol. It is not preferable because it circulates and accumulates throughout the plant.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the conventional method and to provide a method for obtaining a high-purity bisphenol A having excellent hue and low coloring property.

[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, bisphenol A
Washing a crystalline adduct of phenol and phenol with phenol and then removing phenol from the crystalline adduct to obtain bisphenol A, wherein at least a portion of the washing phenol comprises (i) a reaction between phenol and acetone. phenol separated from the product, at least one phenol selected from among (ii) phenol is separated from the crystallization product of a phenol containing bisphenol a and (iii) spent phenol after washing the crystals adduct And its water content is 0.5 weight
% Or less is contacted with a strong acid-type ion exchange resin, and then the distillation temperature is 185 ° C. or less and the distillation pressure is 5 %.
There is provided a method for producing bisphenol A having low coloring properties, characterized in that purified phenol obtained by post-distillation treatment under reduced pressure of 0 Torr to 600 Torr is used.

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 present invention, a reaction step of phenol and acetone with respect to the thus obtained crystalline adduct,
The by-product phenol obtained in the step of concentrating the reaction product, the step of crystallizing phenol containing bisphenol A and the step of washing the adduct are subjected to a washing treatment using purified phenol obtained by purifying the phenol by a specific method. The present inventors have conducted intensive studies on the method for purifying the by-product phenol in order to obtain phenol suitable for washing the crystalline adduct. As a result, after contacting the by-product phenol with a strong acid-type ion exchange resin, distillation was performed. The purified product obtained by the treatment does not contain a coloring agent of the product bisphenol A, and the product bisphenol A obtained by washing the crystal adduct with the purified product and removing phenol from the washed crystal adduct is: It was found that the color was extremely excellent in hue and low in colorability.

In the present invention, the phenol used for washing the crystal adduct is formed, at least in part, from (i) phenol separated from the reaction product of phenol and acetone, and (ii) crystallization of phenol containing bisphenol. A purified product of at least one phenol selected from phenol separated from the product and (iii) used phenol after washing the crystal adduct is used. The reaction product obtained by the reaction of phenol and acetone is
In order to concentrate the produced bisphenol A contained therein, phenol is separated from the reaction product. In the present invention, a purified phenol can be used. When a phenol containing bisphenol A is crystallized to precipitate a crystal adduct, a plurality of crystallization steps and a solid-liquid separation step of a crystallization product are usually employed, and a plurality of types of mother liquor ( Phenol) can be obtained, but in the present invention, a purified product of phenol forming these mother liquors can be used. The purified product of the mother liquor used in the present invention may be a purified product of any of the mother liquors, but it is preferable to use a purified product of the mother liquor separated from the crystallization product obtained in the first crystallization step. . In the present invention,
After washing the crystal adduct, used phenol is obtained. In the present invention, a purified product of this used phenol can also be used advantageously. As a raw material phenol for obtaining the purified phenol used in the present invention, it is preferable to use a phenol having a purity of 99% by weight or more, preferably 99.5% by weight or more. As the washing phenol, another phenol containing no coloring substance can be used together with the purified phenol. Examples of such a phenol include those obtained by bringing an industrial phenol into contact with a strong acid-type ion-exchange resin and then subjecting it to a distillation treatment in the same manner as described above for the purification of the phenol. in this case,
As the industrial phenol, one having a phenol purity of 99.5% by weight or more, preferably 99.93% by weight or more is used. Further, the purification of the industrial phenol can be performed in a step different from the above-mentioned phenol purification, but can also be mixed with the phenol and purified simultaneously.

When purifying phenol, the raw phenol is first treated by contacting it with a strong acid-type ion exchange resin. In this case, a strong acid-type ion exchange resin having a sulfone group is used. Such a strong acid-type ion exchange resin is conventionally well-known. For example, Amberlite and Amberlist available from Rohm and Haas, and Diaion available from Mitsubishi Kasei can be preferably used.
The treatment of phenol using this strong acid-type ion exchange resin is carried out by a method in which phenol is passed through a packed tower containing strong acid-type ion-exchange resin, a method in which phenol is put into a stirring tank containing strong acid-type ion-exchange resin, and stirred. Can be implemented. The processing temperature is 45 to 150C, preferably 50 to 100C. The contact time between the strong acid type ion exchange resin and phenol is 5 to 200 minutes, preferably 15 to 6 minutes.
It takes about 0 minutes. When performing phenol treatment using this strong acid type ion exchange resin, the moisture in the phenol is
It is 0.5% by weight or less, preferably 0.1% by weight or less. If the amount of water is more than this, the impurity conversion effect of the strong acid-type ion exchange resin deteriorates. Removal of water up to 0.5% by weight or less from phenol can be performed by adding a known azeotropic agent to phenol and causing phenol to azeotrope. The phenol that has been contact-treated with the strong acid-type ion-exchange resin contains high-boiling impurities whose impurities have been converted, and the high-boiling impurities are separated as distillation residues by distillation. The distillation column should be operated under the condition that phenol and high-boiling impurities can be separated, but it is necessary to perform the distillation under the condition that high-boiling impurities are not mixed in phenol. It is. If the temperature is 185 ° C. or lower, the operating pressure is arbitrarily set, but is usually 50 Torr to 600 Ton.
It is performed under reduced pressure of rr. If the operating temperature exceeds 185 ° C., decomposition of high-boiling impurities and the like will occur, and the quality of the purified phenol will be deteriorated. The purified phenol obtained by the above treatment has an APHA standard hue of 10 or less, and does not particularly deteriorate the hue even if it adheres to the product bisphenol.

The washing of the crystal adduct with the purified phenol may be carried out by any method capable of sufficiently bringing the crystal adduct into contact with the purified phenol. In this washing treatment, for example, after removing the mother liquor from the crystal adduct in a solid-liquid separation device such as a filter or a centrifugal separator for separating the crystal adduct, purified phenol is introduced into the solid-liquid separation device. And a crystal adduct to which a small amount of mother liquor discharged from the solid-liquid separation device adheres can be washed with purified phenol in a separate stirred tank. The ratio of purified phenol to crystal adduct used was
The proportion is 30 to 1000 parts by weight, preferably 100 to 300 parts by weight, based on 0 parts by weight.

The crystal adduct washed with the purified phenol has purified phenol adhered to its surface. The purified phenol is sent to the phenol removal step from the crystal adduct, where the phenol is removed. The pure bisphenol A product is recovered. Removal of phenol from the crystal adduct can be performed by a conventionally known method, for example, a method such as distillation, extraction, or steam stripping.

[0012]

According to the present invention, a bisphenol A product having excellent hue and low coloring property can be obtained. In the present invention, since a purified product of a specific phenol is used as a washing liquid for the crystal adduct, there are the following advantages. (1) Since an adduct free of impurities, particularly impurities that cause coloring, is obtained, a product bisphenol having high purity, excellent hue, and low colorability can be obtained. (2) Since no solvent is mixed in the cleaning liquid, the cleaning liquid can be circulated and used as it is in the reaction system or the crystallization system.

[0013]

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

Example 1 Bisphenol A having a melting color of 50 APHA, obtained by reacting phenol with acetone in the presence of an acid catalyst and evaporating almost all of the phenol from the resulting reaction product in the form of water. The mixture of phenol and impurities was crystallized to precipitate a crystalline adduct. This slurry solution was filtered under reduced pressure, and the purified phenol obtained by the method described later was washed with 2.5 parts by weight per 1 part by weight of the adduct. The crystal adduct obtained in this way is
Bisphenol A was obtained by substantially completely removing phenol by steam stripping at 5 ° C and 25 torr for 30 minutes. Melt color of this bisphenol A 10-15
APHA was exhibited, and the color was extremely good. Further, the hue of this bisphenol A when it was maintained at atmospheric pressure for 5 hours after melting was 30 APHA, confirming that the colorability was low. The purified phenol used above was of 5 APHA in molten color, and was obtained by dehydrating phenol evaporated and separated from the above reaction product (water content: 0.1 wt%), by Rohm and Haas Company. This is a product obtained by subjecting to contact treatment with Amberlite IR-118H + resin manufactured at a temperature of 80 ° C. for a contact time of 50 minutes, followed by distillation at a distillation column bottom temperature of 175 ° C. and a column top pressure of 560 torr.

Comparative Example 1 A mixture of bisphenol A having a melting color of 50 APHA, phenol and impurities was subjected to crystallization treatment to precipitate a crystalline adduct. This slurry solution was filtered under reduced pressure, and the obtained crystalline adduct was decomposed at 190 ° C. and the by-product phenol recovered was washed with 2.5 parts by weight based on 1 part by weight of the crystalline adduct. The crystal adduct thus obtained was
Bisphenol A was obtained by removing substantially all of the phenol by steam stripping at 75 ° C. and 25 Torr for 30 minutes to give bisphenol A, which had a molten color of 20 APHA. Further, the hue of this bisphenol A when kept at atmospheric pressure for 5 hours after melting was 80 APHA.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Akio Shindo 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Kako Construction Co., Ltd. (56) References JP-A 1-146839 (JP, A) JP-A-58-79942 (JP, A) JP-B-55-34779 (JP, B2) (58) Fields investigated (Int. Cl. ⁶ , DB name) C07C 39/16 C07C 37/68-37/84 C07C 39/04

Claims (1)

(57) [Claims] 1. A method of obtaining a bisphenol A by washing a crystalline adduct of bisphenol A and phenol with phenol and then removing phenol from the crystalline adduct, wherein at least a part of the washing phenol is (i) ) Phenol separated from the reaction product of phenol and acetone, (ii) phenol separated from the crystallization product of phenol containing bisphenol A, and (iii) used phenol after washing the crystalline adduct. I met at least one of phenol is selected
The one whose water content is 0.5% by weight or less,
After contact with strongly acidic ion-exchange resin, distillation temperature
At 185 ° C or lower, distillation pressure is 50 Torr to 600 T
A method for producing bisphenol A having low coloring properties, comprising using purified phenol obtained by distillation under reduced pressure of orr .