JPH05117193A - Production of high-quality bisphenol a - Google Patents

Abstract

PURPOSE:To provide a process for evaporating and removing phenol from a bisphenol A.phenol crystalline adduct to obtain a high-purity bisphenol A having excellent hue in high efficiency. CONSTITUTION:The objective production process is composed of a phenol evaporation stage to obtain bisphenol A having a phenol content of 1-5wt.% by evaporating a phenol solution containing bisphenol A formed from a crystalline adduct having a melt color of <=15 APHA and exhibiting essentially neutral state with a thin-film evaporator at an oxygen concentration of <=0.005vol.% and 160-185 deg.C under a pressure of 15-60Torr and the 1st and 2nd stripping stages comprising the stripping of the bisphenol A obtained by the phenol evaporation stage by counter-currently contacting the bisphenol A with a stripping gas at 170-185 deg.C under a pressure of <=15Torr.

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-grade bisphenol A by evaporating and removing phenol from a bisphenol A / phenol crystal adduct.

[0002]

2. Description of the Related Art Bisphenol A [2,2]
It is known to react excess phenol with acetone in the presence of an acid catalyst to produce [bis (4-hydroxyphenyl) propane]. Further, in order to separate and collect high-purity bisphenol A from this 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 crystal adducts. On the other hand, in order to separate the phenol from the crystal adduct,
A method of melting at 150 ° C., evaporating the melt at a temperature above 180 ° C. and under reduced pressure, and separating and condensing the resulting vapor to separate bisphenol A and phenol (Japanese Patent Publication No.
2-42790) or a crystal adduct of 180 to 200
A method is also known in which the obtained bisphenol A is subjected to steam stripping treatment after evaporating treatment at ℃ (Japanese Patent Laid-Open No. 63-132850). In such a method for separating and removing phenol from a crystalline adduct, the purity of the obtained bisphenol A depends, of course, on the purity of the crystalline adduct itself and the phenol removal rate.
Even if these points are improved, it is not possible to prevent a small amount of coloring-causing substance from being mixed into the obtained product bisphenol A, so that the problem that the hue of the product bisphenol A deteriorates remains. On the other hand, in order to solve such a problem, a method of obtaining bisphenol A having an improved hue by adding oxalic acid or citric acid to a phenol / water / bisphenol A mixture and then subjecting the mixture to distillation is proposed. (Japanese Patent Publication No. 40-19333). In addition, in order to improve the stability of bisphenol A, a method of adding thioglycolic acid, glycolic acid or polyphosphoric acid (Japanese Patent Publication No. 47-43937), or a method of adding lactic acid, malic acid or glyceric acid (Japanese Patent Laid-Open No. Hei 10 (1999) -242242) 2-231444
No.) etc. are also known. However, even with the above method, the effect of improving the hue of bisphenol A was not yet sufficient.

[0003]

DISCLOSURE OF THE INVENTION According to the present invention, when bisphenol A is obtained by evaporating and removing phenol from a crystal adduct, coloring of bisphenol A is suppressed, and highly pure bisphenol A having an excellent hue is efficiently produced. The task is to provide a method.

[0004]

Means for Solving the Problems The inventors of the present invention have completed the invention as a result of intensive research to solve the above problems. That is, according to the present invention, bisphenol A having a melting color of 15 APHA or less under substantially neutral conditions.
A phenol solution containing bisphenol A formed from a phenol crystal adduct was used in a thin film evaporator under the condition that the oxygen concentration in the atmosphere was 0.005 vol% or less and 160 to 1%.
A phenol evaporation step of obtaining a bisphenol A having a phenol content of 1 to 5 wt% by evaporating at a temperature of 85 ° C. and a pressure of 15 to 60 Torr, and bisphenol A obtained in the phenol evaporation step are 170 A first stripping step in which the stripping gas is countercurrently contacted with the stripping gas at a temperature of ˜185 ° C. and a pressure of 15 torr or less, and bisphenol A obtained in the first stripping step is 170˜ 185 ° C temperature and 15
A second stripping step in which the stripping gas is brought into direct contact with the stripping gas under a pressure of not more than torr, and steam is used as the stripping gas in the second stripping step, and the first stripping step is performed. The stripping gas consisting of steam containing the phenol and bisphenol A obtained in the second stripping step is used as the stripping gas in (1), and a method for producing high-quality bisphenol A is provided.

The crystal adduct used as a raw material in the present invention has a melting color APHA of 15 or less under substantially neutral conditions. In the reaction of phenol and acetone to obtain bisphenol A, a strongly acidic substance such as hydrochloric acid, sulfuric acid, or a sulfonic acid type strong ion exchange resin is used as an acid catalyst. Such strongly acidic substances are
In the reaction system of phenol and acetone, in addition to acting as a catalyst, it also exhibits an action of promoting the generation of coloring substances and impurities under heating conditions, and reduces the hue and purity of the recovered bisphenol A and phenol. Therefore, it is proposed to remove or neutralize such a strongly acidic substance after the reaction so as not to flow out to the subsequent dephenoling step involving heating conditions. For example, in a reaction using hydrochloric acid as a catalyst, after the reaction, the product is heated to remove the hydrochloric acid, and residual hydrochloric acid is neutralized with an alkali,
A method of neutralizing the solution to pH 5 to 6 has been proposed (Japanese Patent Publication No. 4).
7-43937). Further, in the method using a strong acid type ion exchange resin, during the reaction, the organic sulfonic acid is desorbed by the decomposition of the ion exchange resin and is mixed into the product, so that the organic sulfonic acid is changed to a weak basic ion exchange resin. A method of neutralizing by using is proposed (US Pat. No. 4)
191843). On the other hand, since the hue and purity of phenol and bisphenol A are lowered not only by the acid but also by the alkali, it is necessary to neutralize the strongly acidic substance with the alkali not to exceed the neutralization point.

As described above, in the reaction in which phenol and acetone are reacted in the presence of a strongly acidic substance, is it necessary to neutralize the strongly acidic substance present in the reaction product after the reaction so that the neutralization point is not exceeded? , Needs to be removed from the reaction system,
Further, when the alkali used for neutralizing the strongly acidic substance remains, it is also necessary to remove this alkali. Further, the strongly acidic substance or alkali present in the reaction product can be removed by using a multi-step crystallization process in the subsequent crystallization process. The crystalline adduct under the substantially neutral condition used in the present invention means a crystalline adduct from which the influence of the strongly acidic substance or the alkaline substance is removed. Such a crystal adduct is added and dissolved in an aqueous methanol solution whose acidity is adjusted to have a pH of 5.0, and a pH of 4.9 is measured by a pH measuring method under the substantially non-ionizing condition of phenol.
It has a pH of 0 to 5.50, and preferably a pH of 4.95 to 5.20. The pH of the crystal adduct described in this specification is obtained by the above-mentioned measurement method. In the present invention, as described above, the crystal adduct is under a substantially neutral condition, and the melt color A of the crystal adduct is A.
A PHA having a PHA of 15 or less is used. A crystal adduct having a melt color APHA of 15 or less can be obtained by increasing the number of crystallization stages in the crystallization step. Further, by washing the crystal adduct with purified phenol, impurities and acidic substances due to the removal of the crystallization filtrate can be removed.

When the crystal adduct is washed with purified phenol, any purified phenol may be used as long as it does not cause coloring of the product bisphenol A and has a low impurity content. In the present invention, as the purified phenol, those having a melting color APHA of 10 or less, preferably 5 or less are preferably used. Examples of the purified phenol that can be preferably used in the present invention include (i) phenol separated from the reaction product of phenol and acetone, (ii) phenol separated from the crystallization product of phenol containing bisphenol, A purified product of at least one phenol selected from (iii) used phenol after washing the crystal adduct and (iv) industrial phenol is used. The reaction product obtained by the reaction of phenol and acetone is separated from the reaction product in order to concentrate the produced bisphenol A contained in the reaction product. In the present invention, the purified product of this phenol is used as a washing liquid. Can be used. In the case where a phenol solution containing bisphenol A is crystallized to precipitate a crystal adduct, a plurality of stages of crystallization steps and a solid-liquid separation step of a crystallization product are usually adopted, and a plurality of mother liquors are correspondingly used. (Phenol solution) is obtained, but in the present invention, the purified product of phenol forming these mother liquors can be used as a washing liquid. The purified product of the mother liquor used in the present invention may be a purified product of any one of those mother liquors, but it is preferable to use the purified product of the mother liquor separated from the crystallization product obtained in the crystallization step in the first stage. .. In the present invention, spent phenol is obtained after washing the crystal adduct, but in the present invention, the purified product of the used phenol can also be advantageously used as a washing liquid. The raw material phenol for obtaining the purified phenol used in the present invention has a purity of 99% by weight or more, preferably 99.5.
It is preferable to use one having a weight% or more. Further, in the present invention, a purified product of industrial phenol can be used as a cleaning liquid. In this case, the industrial phenol has a phenol purity of 99.5% by weight or more, preferably 99.9.
3 wt% or more is used.

Next, the method for obtaining purified phenol from the above-mentioned phenol will be described in detail. First, the phenol is brought into contact with a strong acid type ion exchange resin for treatment. As the strong acid type ion exchange resin, one having a sulfone group is used, and such a strong acid type ion exchange resin is well known in the art. For example, gel-type ones such as Amberlite and Amberlyst available from Rohm and Haas Company, and Diaion etc. available from Mitsubishi Kasei Co. can be preferably used. The treatment of phenol with this strong acid ion exchange resin is carried out by a method of circulating phenol in a packed column containing a strong acid ion exchange resin, a method of stirring by adding phenol to a stirring tank containing a strong acid ion exchange resin, or the like. Can be implemented.
Treatment temperature is 45 to 150 ° C, preferably 50 to 100 ° C
Is. The contact time between the strong acid ion exchange resin and the phenol is 5 to 200 minutes, preferably 15 to 60 minutes. When phenol is treated using this strong acid ion exchange resin, the water content in phenol is 0.5% by weight or less, preferably 0.1% by weight or less. If the water content is higher than this, the effect of impurity conversion by the strong acid ion exchange resin deteriorates. The water content up to 0.5% by weight or less can be removed from phenol by azeotropically adding a known azeotropic agent to phenol. The phenol that has been subjected to the contact treatment with the strong acid ion exchange resin contains high-boiling point impurities, and the high-boiling point impurities are separated as a distillation residue by performing a distillation process. The operating conditions of the distillation column should be such that phenol and high-boiling point impurities can be separated, but it is necessary to carry out under conditions where high-boiling point impurities are not mixed in the distilled phenol, and the point to be noted is that the distillation treatment temperature should be 185 ° C or lower. Is. If the temperature is 185 ° C or lower, the operating pressure is set arbitrarily, but usually 50
It is performed under reduced pressure of Torr to 600 Torr. 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 deteriorate, which is not preferable.
The purified phenol obtained by the above treatment is APHA
The standard hue is 15 or less, particularly 10 or less, and even if it adheres to the crystal adduct and bisphenol A product, the hue is not particularly deteriorated.

In the present invention, a solution containing bisphenol A formed from a crystalline adduct having a melting color of 15 APHA or less under substantially neutral conditions is subjected to substantially oxygen-free reaction using a thin film evaporator. The step of evaporating and removing phenol under reduced pressure is included. In this case, “substantially free of oxygen” means that the oxygen concentration in the atmosphere in the apparatus system for removing phenol by evaporation is 0.005 volppm or less. As a method of making the inside of the apparatus system substantially oxygen-free, there is a method of purging an inert gas such as nitrogen gas or argon gas into the apparatus system, and more preferably, depressurizing the inside of the apparatus system. There is a method of repeating the steps and the step of purging the apparatus system under the reduced pressure with an inert gas.

In the case where phenol is removed by evaporation from a solution containing bisphenol A formed from a specific crystal adduct according to the present invention, an anti-coloring agent can be added if necessary. The anti-staining agent can be added directly to the crystal adduct, in which case the anti-staining agent is added to the crystal adduct in any state, i.e. in the powder, melt, slurry or solution state. It can be mixed. The coloring preventing agent that can be preferably used in the present invention is an aliphatic carboxylic acid. This aliphatic carboxylic acid is bisphenol A in a molten state.
It shows the effect of preventing the coloring of bisphenol A when it is kept in contact with the atmosphere for a long time or kept at a high temperature.
Any aliphatic carboxylic acid may be used as long as it has a color-preventing effect on bisphenol A, and conventionally known ones are used. Examples of such substances include formic acid, oxalic acid, citric acid, tartaric acid, glycolic acid, lactic acid, malic acid, glyceric acid and the like. These compounds decompose or isomerize at a temperature of 160 ° C. or higher during the reaction, and exhibit an excellent action as a color-preventing agent for bisphenol A. The amount of the aliphatic carboxylic acid added is 1 to 1 with respect to the crystal adduct.
The amount is 00 ppm by weight, preferably 5 to 50 ppm by weight. By adding this aliphatic carboxylic acid, it is possible to obtain bisphenol A, which is a product with good heat stability in which coloration during melting is prevented.

Next, the present invention will be described with reference to the drawings.
In FIG. 1, 1, 2 and 3 indicate thin film evaporators. This has a structure in which a thin film formed on the inner peripheral wall of the thin film is evaporated by heating from the outside. In the present invention,
It is preferable to use a centrifugal thin film evaporator having a rotary blade inside and forming a liquid film on the inner peripheral wall surface by the rotation of the rotary blade. Further, in FIG. 1, 4 is an external heater attached to each thin film evaporator. This one is usually
It is configured as a jacket through which the heating medium flows.

In the present invention, the bisphenol A / phenol crystal adduct having a melting color of 15 APHA or less, which is used as a raw material under substantially neutral conditions, is melted by heating or diluted and dissolved with purified phenol. , A phenol solution containing bisphenol A.
The phenol solution preferably used in the present invention has a bisphenol A concentration of 50 to 80% by weight, preferably 60 to 75.
% By weight. The raw material phenol solution is introduced from a line 10 into a first thin film evaporator (hereinafter, also simply referred to as an evaporator) 1, and the phenol solution flows down as a liquid film on the inner peripheral wall of the evaporator, and an external heater is provided therebetween. Heated by 4 and phenol and bisphenol A
The steam containing the is discharged through the line 11. This vapor condenses it to recover phenol and bisphenol A. The temperature of the phenol solution passing through the line 10 is 120 to 150 ° C., and the temperature of the first evaporator 1 is 160.
~ 185 [deg.] C, the pressure is 15-60 Torr, preferably 15-30 Torr. Further, the inside of the first evaporator is maintained under substantially oxygen-free conditions. In the first evaporator 1,
The residual liquid (bisphenol A) obtained by evaporating the raw material phenol solution is withdrawn through the line 12 and
It is introduced into the evaporator 2. The temperature of the residual evaporation liquid of the phenol solution passing through the line 12 is 170 to 185 ° C. The concentration of phenol in bisphenol A constituting this residual liquid is 1 to 5% by weight. In the second evaporator 2, the bisphenol A is heated by the external heater 4 while being countercurrently contacted with the stripping gas consisting of steam, phenol and bisphenol A extracted from the third evaporator 3, and then the bisphenol A is heated. And stripping gas containing steam is discharged through line 13. The temperature in the second evaporator 2 is 170 to 185.
C and pressure are 15 torr or less, usually 10-15 torr. Further, the inside of the second evaporator is kept substantially oxygen-free. The evaporation residual liquid obtained in the second evaporator 2 is the line 14
And is introduced into the third evaporator 3. The temperature of this residual liquid is 170 to 185 ° C., and the phenol concentration in bisphenol A constituting the residual liquid is 0.05 to 0.10% by weight, preferably 0.05 to 0.07% by weight. In the third evaporator 3, the bisphenol A from the second evaporator 2 is heated by the external heater 4 in countercurrent contact with the steam introduced through the line 15, and the stripping gas passes through the line 17. This stripping gas is introduced into the second evaporator 2 as the stripping gas. The temperature in the third evaporator is 170-18
The temperature is 5 ° C and the pressure is 15 torr or less, usually 10 to 15 torr. Further, the inside of the third evaporator is kept substantially oxygen-free. The amount of steam introduced into the third evaporator 3 from the line 15 is 3% by weight or more in weight ratio with respect to bisphenol A introduced into the third evaporator 3 through the line 14.
It is preferably 4 to 6% by weight. The composition of the stripping gas passing through the line 17 is phenol: 0.8 to 1.2.
% By weight, preferably 1% by weight or less, bisphenol A:
5 to 7% by weight, balance: steam. The high-purity bisphenol A obtained in the third evaporator 3 is
Be pulled out through. This bisphenol A has a phenol content of 0.005% by weight and its hue AP
HA has a high quality of 20 or less.

The stripping gas extracted from the second evaporator 2 through the line 13 is subjected to a condensation treatment, and the phenol and bisphenol A contained in the gas are separated and recovered. A preferred method for condensing the stripping gas will be described below. Line 13 as above
The stripping gas obtained through the above is supplied to the first cooling step in the depressurized state, where it is countercurrently contacted with a first cooling medium composed of phenol or phenol containing bisphenol A to be cooled. This first cooling step is carried out so that substantially all of the bisphenol A in the stripping gas is dissolved in the cooling medium. The steam in the stripping gas is not substantially condensed in this first cooling step and is sent to the next second cooling step. Part of the phenol in the stripping gas is condensed in this first cooling step, and the remaining uncondensed one is sent to the next second cooling step together with steam. A part of the mixed liquid of bisphenol A and phenol separated and recovered from the stripping gas in the first cooling step can be used as a cooling medium. The temperature of the first cooling medium is about 1 to 50 ° C. higher than the freezing point of phenol. The recovery rate of phenol in the first cooling step is 70% by weight or more, preferably 85% by weight or more, based on the total amount of phenol supplied to the first cooling step.

The cooling medium used in the first cooling step may be an amount sufficient to cool the stripping gas to a desired temperature, and is usually in a weight ratio to the stripping gas.
It is 5 to 10, preferably 5 to 6. In addition, bisphenol A in the stripping gas obtained in the first cooling step
The weight ratio of bisphenol A to phenol contained in the cooling medium in which phenol and phenol are dissolved is 0.05 to
It is 0.20, preferably 0.08 to 0.14. First
In the cooling step, since excess phenol is present with respect to bisphenol A, the crystal adduct between bisphenol A and phenol does not crystallize even at a cooling temperature below the freezing point of bisphenol A.

The pressure of the first cooling step is 30 Torr or less,
It is preferably 5 to 20 Torr and corresponds to the pressure in the second thin film evaporator 2. Further, the temperature in the first cooling step is a temperature at which steam holds gas and a part of phenol holds liquid under the pressure condition. Preferred cooling temperature (temperature at which bisphenol A is condensed)
Is about 1 to 50 ° C. higher than the freezing point of phenol, and the cooling temperature is 42 to 90 ° C., preferably 45.
~ 55 ° C.

The mixed gas of steam and phenol sent to the second cooling step is cooled by being brought into countercurrent contact with a second cooling medium composed of an aqueous solution of phenol. This second cooling step is carried out so that substantially all of the steam and phenol sent to this step are condensed and liquefied, and an aqueous phenol solution is recovered from this step. A part of the aqueous phenol solution obtained in the second cooling step can be used as the second cooling medium. The concentration of phenol in the aqueous solution depends on the composition of the stripping gas and the conditions of the first cooling step, but it is usually 55 to 75% by weight. The temperature of the second cooling medium is about 1 to 10 ° C. lower than the condensation temperature of steam. The second cooling medium used in the second cooling step may be an amount sufficient to condense the total amount of the mixed gas, and is usually a weight ratio to the mixed gas of steam and phenol sent from the first cooling step, 1
It is from 00 to 300, preferably from 190 to 250. The pressure in this second cooling step is 30 Torr or less, preferably 5 Torr.
~ 20 Torr, corresponding to the pressure of the first cooling step.
Cooling temperature in the second cooling step (steam condensing temperature)
May be at a temperature at which the entire amount of the mixed gas of steam and phenol is condensed and liquefied under the above pressure conditions.

The cooler used in the first cooling step and the second cooling step may be any gas-liquid contact type device, and any one may be used. As such a cooler, for example, a packed tower or a spray tower can be used. When using a packed column, it is preferable to use a Raschig ring, a pole ring, a porous metal plate or the like as the packing so as to suppress the pressure loss. In addition, the first cooling step and the second
The coolers used in the cooling step may be installed separately, but may be a one-column type device including two coolers.

Next, one embodiment of the method for condensing the stripping gas will be described with reference to the drawings. In FIG. 2, 21 indicates a first cooler and 22 indicates a second cooler. The line 23 is the line 13 shown in FIG.
Shows the stripping gas line connected to. Line 2
Reference numeral 4 denotes a vacuum line connected to an exhaust pump (not shown) and a cooler, and the entire system including the cooler is kept under reduced pressure. The stripping gas is supplied to the lower part of the first cooler 21 through the line 23, where the line 25
A first cooling medium (phenol or phenol containing bisphenol A) introduced through the top of the first cooler through
Come into countercurrent contact with. The cooling medium in which bisphenol A and phenol which have been condensed in the first cooler are dissolved is withdrawn from the bottom of the first cooler through a line 26 including an extraction pump 27. The cooling medium extracted through this line 26 is cooled partially to a required temperature, if necessary, and then cooled.
It can also be recycled to the line 25 as a cooling medium.

The mixed gas of steam and phenol extracted from the top of the first cooler 21 through the line 28 is introduced into the lower part of the second cooler 22, where the second cooler is passed through the line 29. In countercurrent contact with a second cooling medium (aqueous solution of phenol) introduced from above. In the second cooler, the mixed gas of steam and phenol is condensed and liquefied, and this condensed liquid is discharged together with the cooling medium from the bottom of the second cooler 22 through a line 30 including a pump 31,
A part of it passes through the line 33 and a cooler 34 for the cooling medium.
After being cooled through the line 29, it is recycled to the second cooler through the line 29. The remainder of the cooling medium containing condensed steam and phenol extracted through the line 30 is extracted outside the system through the line 32.

Next, FIG. 3 shows an apparatus system diagram when a one-column type cooling device including a first cooler and a second cooler is used in the stripping gas condensation treatment method. In FIG. 3, reference numeral 40 denotes a one-column type cooling device having a first cooler 21 and a second cooler 22 therein. In this cooling device, a partition plate 45 having an opening in the center is arranged between the first cooler 21 and the second cooler 22, and the cylindrical body 4 is provided in the opening.
3 has an upright structure. In this device, the cylinder 4
The annular hollow chamber formed between the outer peripheral surface of 3 and the inner wall of the cooling device 40 is for storing a liquid. 42
Is a guide plate for guiding the liquid flowing down the second cooler 22 to the annular hollow chamber. The cylindrical space 44 represents a gas passage. In the reference numerals in FIG. 3, the same reference numerals as those shown in FIG. 2 have the same meanings. The flow rate control system shown in FIG. 2 is not shown in FIG.

According to the above stripping gas condensation treatment method, the stripping gas is heated to 30% without increasing the pressure.
It is possible to cool and condense under a reduced pressure condition of not more than torr. Moreover, in this case, crystals of bisphenol A and phenol do not precipitate at all, despite the low pressure condition of 30 Torr or less and the low steam condensation temperature condition corresponding thereto. Therefore, in this stripping gas condensing treatment method, there is no decrease in the efficiency of the cooler due to solid deposition and no clogging trouble of the cooler. Further, according to the condensation treatment of the stripping gas, all of steam, phenol and bisphenol A constituting the stripping gas are condensed, and the gases are not substantially flowed into the vacuum exhaust system. Therefore, the vacuum exhaust pump only needs to keep the apparatus system under a predetermined depressurization condition, so that it requires only a small exhaust capacity and is very advantageous in terms of equipment cost and energy cost.

[0022]

INDUSTRIAL APPLICABILITY In the present invention, bisphenol A derived from bisphenol A / phenol crystal adduct having a melting color of 15 APHA under substantially neutral conditions.
Oxygen concentration in atmosphere of phenol solution containing 0.005
First, under the condition of vol% or less, a bisphenol A having a phenol content of 1 to 5 wt% is obtained by evaporating with the first thin film evaporator. In the case of the present invention, the temperature of the first thin film evaporator is Since the temperature was maintained at 160 to 185 ° C. and the pressure was 15 to 60 torr, even if cooling was caused by rapid evaporation of phenol, bisphenol A did not precipitate, and the evaporation treatment should be carried out smoothly. You can
Further, in the present invention, the bisphenol A obtained from the first evaporator as described above is subjected to steam stripping treatment using a thin film evaporator in order to evaporate and remove the phenol contained therein. In this case, since the phenol content in bisphenol A was as low as 1 to 5% by weight and two thin film evaporators were used in series, the temperature of those evaporators was maintained at 170 to 180 ° C. And the phenol in the bisphenol A can be removed by evaporation by maintaining a high vacuum of 15 Torr or less, and the hue is excellent, and the high-purity bisphenol having a phenol content of 0.005 wt% or less. A can be obtained.

In order to obtain biphenol A having an excellent hue, the phenol solution containing bisphenol A, which is a raw material for producing it, and the temperature at which the solution is subjected to evaporation treatment are set to 1
It is necessary to keep the temperature below 85 ° C. to suppress the formation of colored impurities such as inpropenylphenol, but in the case of the present invention, the evaporation treatment temperature is kept below 185 ° C. and the inside of the evaporator is substantially maintained. The resulting bisphenol A is a highly pure product having a hue of APHA of 20 or less, which is excellent, because the phenol is substantially completely removed by evaporation by keeping it under anoxic conditions. Furthermore, in the present invention, since the stripping gas composed of steam containing phenol and bisphenol A produced in the third thin film evaporator is used as the stripping steam gas for the second thin film evaporator, the second thin film evaporator is used. There is also an advantage that the phenol stripping effect in the above becomes high. According to the evaporation treatment of the present invention, a very short residence time (usually 6
Since the evaporation treatment can be performed in 0 to 120 seconds), the treatment efficiency is extremely high. In particular, in the case of the present invention, it is desirable that the first thin film evaporator, the second thin film evaporator, and the third thin film evaporator are connected in this order from above, and the liquid flow is made to flow downward from above by gravity. Oxygen leaves can be effectively prevented by this, and the residence time of the liquid in the system can be kept short.

[0023]

EXAMPLES Next, the present invention will be described in more detail by way of examples. Example 1 A reaction mixture obtained by reacting phenol with acetone in the presence of an acid catalyst was subjected to a multi-stage crystallization treatment, and was under substantially neutral conditions (pH 5.05) and had a melting color. APHA
The bisphenol A / phenol crystal adduct of 5 was partially diluted with purified phenol and heated to 130 ° C. to obtain a phenol solution containing 30% by weight of bisphenol A. This phenol solution was used as a raw material liquid and treated using the evaporator system shown in FIG. Next, the main operating conditions of the apparatus system shown in FIG. 1 and the component composition of the liquid passing through the main lines will be shown below. (1) First evaporator 1 (i) External heater temperature: 170 ° C. (ii) Internal pressure: 20 Torr (iii) Oxygen concentration in atmosphere: 0.0010 vol% (2) Second evaporator 2 (i) External heater Temperature: 180 ° C (ii) Internal pressure: 10 Torr (iii) Oxygen concentration in atmosphere: 0.0030vol% (3) Third evaporator 3 (i) External heater temperature: 180 ° C (ii) Internal pressure: 10 Torr ( iii) Oxygen concentration in atmosphere: 0.0030 vol% (4) Bisphenol A passing through the line 16 (i) Phenol content: 29 wtppm (ii) Melt color: APHA15 (5) Steam supply amount passing through the line 15: Passing through the line 14 0.04 parts by weight per 1 part by weight of bisphenol A

Example 2 In Example 1, 20 wtpp of the additive shown in Table 1 was added to a phenol solution containing bisphenol A as a raw material.
The experiment was conducted in the same manner except that m was added. Through this experiment, high purity bisphenol A (A
PHA: 10 and phenol content: 27 wtppm) were obtained. Next, this bisphenol A was subjected to a thermal stability test (test A) in which it was heated and maintained at 175 ° C. for 0 hours or 2 hours in an air atmosphere and an accelerated thermal stability test (test in which air was blown at 175 ° C. for 2.0 hours). B), and the hue at that time was evaluated. The results are shown in Table 1.

[0025]

[Table 1]

Example 3 Bisphenol A having a melting color of 50 APHA obtained by reacting phenol with acetone in the presence of an acid catalyst,
Crystallizing a mixture of phenol and impurities in multiple stages,
A crystal adduct was deposited. This slurry solution was filtered under reduced pressure to obtain a solid crystalline adduct, and the purified phenol obtained by the method described below was used at a ratio of 2.5 parts by weight to 1 part by weight of the adduct to wash the crystal adduct (hue: AP
HA5-10, pH 5.05 or less) was obtained. Next, 1 part by weight of purified phenol was added to 1 part by weight of this crystal adduct, and the mixture was melted at 130 ° C., and then the obtained melt (pH 5.
05) was evaporated in the same manner as in Example 1 to obtain high-purity bisphenol A (purity 99.96 wt%). The phenol content of this bisphenol A is 30 wtpp
and the melt color was 15 APHA.

The purified phenol used above had a melting color of 6APHA, and was used as a commercial industrial phenol (water concentration 0.1 wt%, impurity concentration 0.05 wt%).
Amber Light IR-11 manufactured by Rohm and Haas
Contact treatment using 8H + resin at a temperature of 80 ° C. and an adhesion time of 50 minutes, distillation bottom temperature 175 ° C., top pressure 560 torr
It was obtained by distillation at r.

[Brief description of drawings]

FIG. 1 shows an example of an apparatus system diagram when implementing the present invention.

FIG. 2 shows an example of a system diagram for condensing stripping gas.

FIG. 3 shows another example of a system diagram for condensing the stripping gas.

[Explanation of symbols]

 1, 2, 3 thin film evaporator 4 external heater 21 first cooler 22 second cooler 34 cooler

Front page continued (72) Inventor Makoto Yasui 12-12, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kako Construction Co., Ltd. (72) Noriyuki Yoneda 2--12, Tsurumi-chu, Tsurumi-ku, Yokohama, Kanagawa No. 1 in Chiyoda Kakoh Construction Co., Ltd. (72) Inventor Sachio Asaoka 2-12-1, Tsurumi Chuo, Tsurumi-ku, Yokohama-shi, Kanagawa Chiyoda Kakoh Construction Co., Ltd.

Claims (3)

[Claims] 1. A substantially neutral condition with a melt color of 1.
Using a thin film evaporator, a phenol solution containing bisphenol A formed from bisphenol A / phenol crystal adduct of 5 APHA or less was used, and the oxygen concentration in the atmosphere was adjusted to 0.
Temperature of 160-185 ° C and 1 under the condition of 005 vol% or less
A phenol evaporation step of obtaining a bisphenol A having a phenol content of 1 to 5 wt% by evaporating under a pressure of 5 to 60 Torr and a bisphenol A containing phenol obtained in the phenol evaporation step are 170 to 185. A first stripping step in which the stripping gas is countercurrently contacted with the stripping gas at a temperature of 15 ° C. and a pressure of 15 torr or less, and bisphenol A containing phenol obtained in the first stripping step are added to 170 ~ 185 ° C
And a second stripping step in which the stripping treatment is carried out in countercurrent contact with the stripping gas at a temperature of 15 torr or less, and steam is used as the stripping gas in the second stripping step.
A method for producing high-quality bisphenol A, wherein a stripping gas consisting of steam containing phenol and bisphenol A obtained in the second stripping step is used as the stripping gas in the first stripping step. 2. The method according to claim 1, wherein a phenol solution containing bisphenol A formed from the bisphenol A / phenol crystal adduct is added and mixed with a fatty acid carboxylic acid, and then phenol is removed. 3. The method according to claim 1, wherein the bisphenol A / phenol crystal adduct has been redissolved and recrystallized at least once and then washed with purified phenol.