JP2000327614A - Production of bisphenol a - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain bisphenol A as the final product with low phenol content through suppressing its decomposition during the production process. SOLUTION: The method for producing this bisphenol A comprises setting up a filter of glass fiber at least one position between steps (a) and (b), steps (b) and (c), and steps (d) and (e). These steps comprise: (a) bisphenol A is formed by condensation reaction between phenol and acetone in the presence of an acid catalyst; (b) a low-boiling component and the catalyst are removed from the resultant reaction mixed liquid; (c) adduct crystal composed of the bisphenol A and phenol is deposited and separated by cooling the mixed liquid produced in the step (b); (d) the adduct crystal thus separated is heated and melted; (e) the phenol is removed from the resultant melt to obtain the bisphenol A in a molten state; and (f) the melt thus obtained is cooled and solidified, and then granulated to obtain the objective bisphenol A as a granular product.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing bisphenol A, a compound useful as a raw material for epoxy resins and polycarbonate resins, and more particularly to a method for producing bisphenol A having a low phenol content. .

[0001]

2. Description of the Related Art Bisphenol A is usually produced by reacting phenol with acetone in the presence of an acidic catalyst. As the acidic catalyst used here, a strongly acidic ion exchange resin is typical. The product liquid after the reaction is sent to a purification step, and after removing low-boiling substances such as unreacted acetone and reaction by-product water, cooling is performed to precipitate adduct crystals of bisphenol A and phenol. Then, phenol is removed by vacuum distillation or the like to obtain molten bisphenol A, and the molten bisphenol A is cooled by a spray dryer or the like to granulate.

When a strongly acidic ion exchange resin is used as a catalyst for synthesizing bisphenol A, an acidic substance may be eliminated from the ion exchange resin. When exposed to high temperatures, the desired product bisphenol A is decomposed and acidic by-products such as phenol and isopropylphenol may be produced. By-products such as phenol in bisphenol A act as a polymerization terminator, particularly when producing a polycarbonate resin, and inhibit the reaction, or the volatility of these phenols deteriorates the operation operability. May cause problems.

[0003] In order to suppress the production of phenol and the like, a method for neutralizing acidic free acid is disclosed in
JP-A-72133 proposes a method of adding a metal carbonate to a phenol solution of bisphenol A,
In this method, it is generally difficult to adjust the amount of the metal carbonate added, and the operability is not very good. Japanese Patent Application Laid-Open No. 8-325184 discloses bisphenol A.
A method of treating the phenol solution with a fluororesin membrane filter has been proposed, but it has been difficult with this method to completely remove trace amounts of molten impurities.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing bisphenol A having a low phenol content by suppressing the decomposition of bisphenol A during the production process.

[0005]

Means for Solving the Problems The present inventors have made various studies to solve the above-mentioned problems, and as a result, by passing a phenol solution of bisphenol A through a glass fiber filter, The inventors have found that the problems can be solved and completed the present invention.

That is, the gist of the present invention is to provide (1) a method for producing bisphenol A comprising the following steps: between steps (a) and (b), between steps (b) and (c).
And a method for producing bisphenol A, wherein a glass fiber filter is provided at at least one position between step (d) and step (e).

(A) a step of subjecting phenol and acetone to a condensation reaction in the presence of an acidic catalyst to form bisphenol A; (b) a step of removing the low-boiling components and the catalyst from the reaction mixture obtained in step (a) Step (c): cooling the mixture obtained in step (b) to precipitate and separate adduct crystals of bisphenol A and phenol; and (d) heating and melting the adduct crystals obtained in step (c). (E) Step of removing phenol from the melt obtained in step (d) to obtain bisphenol A in a molten state. (F) Cooling and solidifying the melt obtained in step (e), granulating it, and forming granules. Step of obtaining product bisphenol A

Another gist of the present invention is that (2) the composition of the glass fiber filter is at least one of silicon oxide, aluminum oxide, an oxide of an alkali metal element and an oxide of an alkaline earth metal element. (3) the content of silicon dioxide in the glass fiber filter is 30 to 90% by weight, and the content of aluminum oxide is 2;
The present invention also provides the method for producing bisphenol A, wherein the content of the alkali metal oxide is 25% by weight or less and the content of the alkaline earth metal is 25% by weight or less.

Further, another gist of the present invention is to provide (4) a method for producing bisphenol A in which the acidic catalyst used in the step (a) is a strongly acidic ion exchange resin, and (5) a method for producing the bisphenol A obtained in the step (e). The present invention also provides a method for producing bisphenol A, wherein the phenol content in the resulting bisphenol A is 20 ppm by weight or less.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. As described above, the present invention provides, among the following steps for producing bisphenol A, a step between step (a) and step (b), a step between step (b) and step (c), and a step (d). A glass fiber filter is installed at least at one point between the step (e).

Each step will be described individually. Step (a) In step (a), phenol and acetone are subjected to a condensation reaction in the presence of an acidic catalyst to produce bisphenol A. The raw materials phenol and acetone used here are reacted under conditions where the phenol is in excess of the stoichiometric amount. The molar ratio of phenol to acetone is in the range of 3 to 30, preferably 5 to 20, as phenol / acetone ratio. The reaction temperature is usually 30 to 100 ° C, preferably 50 to 90 ° C, and the reaction pressure is generally normal pressure to 5 kg / c.
m ² · G.

When an ion exchange resin is used as the acidic catalyst, a sulfonic acid type cation exchange resin having a gel type and a degree of crosslinking of 1 to 8%, preferably 2 to 6% is suitable, but is not particularly limited. Absent. Further, hydrochloric acid may be used as an acid catalyst. The reaction mixture formed in the step (a) generally contains by-products such as unreacted phenol, unreacted acetone, catalyst, reaction product water, and colored substances, in addition to bisphenol A.

Step (b) Step (b) is a step of removing low boiling components and a catalyst from the reaction mixture obtained in step (a). The term "low-boiling component" used herein refers to water produced by reaction, unreacted acetone, and those having boiling points close to these. In this step, these low-boiling components are removed from the reaction mixture by, for example, distillation under reduced pressure, and solid components such as a catalyst are removed by filtration or the like. When a fixed-bed catalytic reactor is used, there is no particular need for decatalysis. Vacuum distillation has a pressure of 50 to 300 mmHg,
It is preferable to use a temperature in the range of 70 to 130 ° C., and unreacted phenol may azeotropically remove a part of the phenol from the system.

Step (c) In the step (c), the mixture obtained in the step (b) is cooled,
This is a step of precipitating and separating adduct crystals of bisphenol A and phenol. Prior to this step (c),
The concentration of bisphenol A in the mixture obtained in the step (b) is adjusted to 20 to 50% by weight, preferably 3 to 50% by weight by removing or adding phenol.
Adjusting the content to 0 to 45% by weight is preferable in increasing the yield of the adduct and adjusting the apparent viscosity of the slurry-like mixture to improve the workability.

The cooling in the step (c) is generally carried out at 45 to 45%.
The reaction is carried out to a temperature of 60 ° C., whereby crystals of an adduct of bisphenol A and phenol are precipitated, and the system becomes a slurry. This cooling is performed by heat removal by latent heat of vaporization of water added to a heat exchanger or a crystallizer provided outside. Next, the slurry-like liquid is separated into an adduct crystal and a mother liquor containing a reaction by-product by filtration, centrifugation, or the like,
The adduct crystals are subjected to the next step. The separated mother liquor is preferably recycled to, for example, the previous stage of the step (b) or the step (a) to further improve the reaction yield.

Step (d) Step (d) is a step of heating and melting the crystal of the adduct obtained in step (c). The composition of the adduct crystals was bisphenol A 45-70% by weight, phenol 55-70% by weight.
It is generally in the range of 30%. This crystal is
It is melted by heating to 0 to 160 ° C. and provided for the next step.

Step (e) Step (e) is a step in which phenol is removed from the melt obtained in step (d) to obtain molten bisphenol A.
The phenol is removed from the melt obtained in the step (e) by a method such as distillation under reduced pressure to dissociate the adduct, whereby high-purity bisphenol A can be recovered. This vacuum distillation is performed at a pressure of 10 to 100 mmHg and a temperature of 150 to 1
Bisphenol A present in the temperature range of 90 ° C and in the system
It is preferably carried out at a temperature at least 10 ° C. higher than the melting point of the mixture of phenol and phenol. A method of removing residual phenol by performing steam stripping in addition to vacuum distillation has also been proposed. (For example, Japanese Patent Application Laid-Open No.
No. 6, JP-A-63-132850, etc.)

Step (f) Step (f) is a step of cooling and solidifying the bisphenol A in a molten state obtained in step (e), and granulating to obtain a granular product. Bisphenol A in a molten state is formed into droplets by a granulating device such as a spray drier and solidified by cooling to produce a product. The droplets are prepared by spraying, dripping, spraying, etc., and the cooling is usually performed with nitrogen or air.

In the method of the present invention, when bisphenol A is in a molten state as a phenol solution or as an adduct with phenol, the solution is passed through a glass fiber filter. Specifically, at least one place between the steps (a) and (b), between the steps (b) and (c), and between the steps (d) and (e), the glass fiber And a liquid is passed through the filter.

In particular, it is preferable to install this filter between step (d) and step (e), that is, before subjecting the melt of the adduct crystals to the phenol removal step. This is at 180 ° C. used during the dephenol treatment in step (e).
This is because it is possible to effectively suppress the decomposition of bisphenol A at the above high temperature and the production of phenol, isopropylphenol, and the like due to the decomposition. When the concentration of bisphenol A in the mixture is adjusted prior to step (c), the glass fiber filter may be installed before or after this concentration adjustment process. Absent.

Examples of the glass fiber filter used in the method of the present invention include a depth type cartridge filter in which glass fibers are regularly spirally wound. Commercially available products of such a filter include the MPF-J series manufactured by Cuno and the Fujiwind filter element manufactured by Fuji Filter.

The filtration accuracy (pore size) of the filter is as follows:
Although it depends on the particle size and content of the impurity particles contained in the liquid to be treated, the pressure loss of the filter, and the like, it is preferable to use those having a particle size of 20 μm or less. As the composition of the glass fiber filter, it is preferable to use one containing at least one kind of oxides of alkali earth metals such as magnesium oxide and calcium oxide such as silicon oxide, aluminum oxide and alkali metal oxide such as sodium, In particular, the content of silicon dioxide is 30 to 90% by weight, the content of aluminum oxide is 2 to 25% by weight, the content of alkaline earth metal oxide such as calcium oxide is 25% by weight or less, Those having an alkali metal oxide content of 25% by weight or less are preferred. Among them, those having an aluminum oxide content of 2 to 10% by weight are preferred. By the treatment according to the above method, a phenol content of 20 which can be used for polymerization or the like even by a usual purification method.
Bisphenol A having a high purity of not more than ppm by weight can be stably obtained.

[0023]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In the examples, “%” and “ppm” represent “% by weight” and “ppm by weight” unless otherwise specified. The quantitative analysis of phenol and bisphenol A was performed by high performance liquid chromatography (HPLC analysis). Further, the composition of the glass filter was calculated assuming that each metal was present as an oxide, by fluorescent X-ray analysis, in terms of% by weight.

Example 1 Bisphenol A was produced according to the process shown in FIG. A glass fiber filter (MPF-J series cartridge filter manufactured by Cuno, filtration accuracy = 10 μm) was installed between step (d) and step (e). The dephenolization treatment in the step (e) was carried out using a distillation column of 15 mmHg and 170 ° C. and a steam stripping column provided at the subsequent stage. In step (f), a prill tower was provided to produce prill-like bisphenol A. Even after a continuous operation for 55 days with a new cartridge filter attached, the amount of residual phenol in the product bisphenol A was 20 ppm or less.

Example 2 The above-described Example 1 was repeated except that a glass fiber filter having a different composition (Fujiwind filter element manufactured by Fuji Filter Co., Ltd., filtration accuracy = 10 μm) was used as a filter medium for the glass filter.
The continuous operation was performed in the same manner as described above. The continuous operable period until the phenol content in the product bisphenol A exceeded 20 ppm was 8 days.

Example 3 A continuous operation was carried out in the same manner as in Example 1 except that the installation position of the glass fiber filter was between the steps (a) and (b). The continuous operable period until the phenol content in the product bisphenol A exceeded 20 ppm was 16 days.

Example 4 A continuous operation was carried out in the same manner as in Example 1 except that the installation position of the glass fiber filter was between the steps (b) and (c). The continuous operable period until the phenol content in the product bisphenol A exceeded 20 ppm was 12 days.

<Comparative Example 1> An operation was performed in the same manner as in Example 1 except that a membrane filter made of polytetrafluoroethylene (PTFE) was used instead of glass fiber as a filter medium of the filter. The amount of phenol in A could not be reduced to 20 ppm or less.

<Comparative Example 2> Bisphenol A was produced in the same manner as in Example 1 except that no filter was used, but the phenol content in the product bisphenol A could not be reduced to 20 ppm or less. . The results are summarized in the table.

[0030]

[Table 1]

Continuous operation period: Number of continuous operation days until the phenol content in the product bisphenol A exceeds 20 ppm

[0032]

According to the method of the present invention, high-quality bisphenol A having a low phenol content and usable as a polycarbonate resin raw material can be stably obtained.

[Brief description of the drawings]

FIG. 1 is a block flow diagram illustrating a possible embodiment of the present invention.

[Explanation of symbols]

(A) to (f): each step of the production of bisphenol A. ：: a place where the glass fiber filter of the present invention can be installed.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masahiko Nakamoto 17-1 Towada, Kamisu-cho, Kashima-gun, Ibaraki Pref. 4H039 CA60 CF30 CG10

Claims (5)

[Claims] 1. A method for producing bisphenol A comprising the following steps: between step (a) and step (b), between step (b) and step (c), and between step (d) and step (B) a method of producing bisphenol A, wherein a glass fiber filter is provided at least at one position between the two. (A) a step of subjecting phenol and acetone to a condensation reaction in the presence of an acidic catalyst to form bisphenol A; (b) a step of removing low boiling components and a catalyst from the reaction mixture obtained in step (a) (c) ) Cooling the mixture obtained in step (b) to precipitate and separate adduct crystals of bisphenol A and phenol; and (d) heating and melting the adduct crystals obtained in step (c). Step of removing phenol from the melt obtained in step (d) to obtain bisphenol A in a molten state (f) Cooling and solidifying the melt obtained in step (e), granulating it, and granulating the product bisphenol A The process of obtaining 2. The bisphenol according to claim 1, wherein the composition of the glass fiber filter contains at least one of silicon oxide, aluminum oxide, an oxide of an alkali metal element and an oxide of an alkaline earth metal element. A production method. 3. The glass fiber filter has a silicon dioxide content of 30 to 90% by weight, an aluminum oxide content of 2 to 25% by weight, an alkali metal oxide content of 25% by weight or less, and an alkali. 2 earth metal content
The bisphenol A according to claim 2, which is not more than 5% by weight.
Manufacturing method. 4. The method for producing bisphenol A according to claim 1, wherein the acidic catalyst used in the step (a) is a strongly acidic ion exchange resin. 5. Bisphenol A obtained in step (e)
The method for producing bisphenol A according to any one of claims 1 to 4, wherein a phenol content in the phenol is 20 ppm by weight or less. [0001]