JPH08119893A - Production of bisphenol a - Google Patents

Abstract

PURPOSE: To produce bisphenol A having high purity and excellent hue and useful as a raw material for epoxy resin and polycarbonate resin in a short time by subjecting a crystal of an addition product of bisphenol A and phenol to dephenolation in solid state at a specific temperature. CONSTITUTION: The objective bisphenol A is produced by dephenolating (A) a crystal of an adduct of bisphenol A and phenol [e.g. a crystal of an adduct of bisphenol A and phenol having a bisphenol A weight ratio (WA) of 0.5-0.71] at 50-153 deg.C while keeping the solid state. The dephenolation reaction is carried out preferably by dephenolating at 50-98 deg.C under the pressure of inert gas flow until the WA reaches 0.94 and dephenolating at 145-l53 deg.C when WA reaches 0.99 or over. The component A is produced usually by reacting excess phenol with acetone in the presence of an acidic catalyst and crystallizing the reaction product containing bisphenol A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to colorless and highly pure bisphenol A [2,2-bis (4-hydroxyphenyl) by removing phenol from an adduct crystal of bisphenol A and phenol. [Propane]. Bisphenol A is a compound useful as a raw material for epoxy resins and polycarbonate resins.

[0002]

BACKGROUND ART Bisphenol A is generally obtained by precipitating an equimolar adduct crystal of bisphenol A and phenol from a product obtained by reacting phenol and acetone in the presence of an acidic catalyst. It is produced by removing phenol from the product crystals. In order to meet the demand for higher quality resins made from bisphenol A,
Although colorless and high-purity bisphenol A is required, the purity and hue of the product bisphenol A also depend on the process of dephenoling from the adduct crystals.
As a method for separating bisphenol A without deteriorating the hue, for example, a melted adduct crystal is melted at 180 ° C.
As described above, the method of vaporizing under reduced pressure for 0.1 to 30 minutes to separate and condense bisphenol A and phenol (Japanese Patent Publication 5)
2-42790), methods such as vacuum distillation, steam stripping and the like are being investigated.

However, in these methods, since the treatment is carried out at a temperature higher than the melting temperature of the adduct crystal, a color-causing substance such as isopropenylphenol is generated, and thus the deterioration of the hue of the product bisphenol A cannot be sufficiently suppressed. There is. Further, the method of performing vacuum distillation (Japanese Patent Laid-Open No. 5-78270) at a melting point (about 100 ° C.) or lower of the adduct crystals can suppress deterioration of hue, but since the vapor pressure of phenol at the processing temperature is low, There is a problem that the dephenolization rate is slow after the content becomes very small.

[0004]

DISCLOSURE OF THE INVENTION The present invention aims to provide a method for producing bisphenol A having a high purity and a good hue from a crystal of an adduct of bisphenol A and phenol by a simple method and efficiently. To do.

[0005]

The present invention is directed to a bisphenol
High-purity and good hue, which is characterized in that bisphenol A is obtained by dephenoling the adduct crystal of the phenol A and phenol in a solid state at a temperature of 50 ° C to 153 ° C.
A method for producing bisphenol A is provided. In the present invention, maintaining the solid state means that 80% or more of the surface of the adduct crystal of bisphenol A and phenol and the mixture of bisphenol A and adduct crystal formed in the dephenol process. It means to keep unmelted state.

Crystals of an adduct of bisphenol A and phenol are usually obtained by crystallizing a reaction product containing bisphenol A obtained by reacting excess phenol with acetone in the presence of an acidic catalyst. This adduct crystal is a crystal in which about 1 mol of phenol is added to 1 mol of bisphenol A, and the phenol content is a theoretical value of about 29%, but after the separation by filtration due to adhesion of mother liquor to the crystal surface, etc. Since the phenol content increases, it is generally 29 to 50% by weight, and the weight fraction of bisphenol A is 0.5 to 0.71.

The adduct crystals are needle-like crystals and generally have a length of 0.05 to 2.0 mm and a width of 0.01 to 0.5 mm, preferably 0.1 to 1.5 mm in length and 0. 1 to 0.3
mm crystals are subjected to the method of the invention. If the crystals are too small, it becomes difficult to remove the impurities contained in the adhering crystallization mother liquor, and large crystals are not suitable as an industrial method because the efficiency of the crystallization process will decrease. . If necessary, the adduct crystals can be washed with purified phenol to improve the purity and the hue. The hue of the adduct crystals used in the method of the present invention is a melt color of 15 APH.
It is preferably A or less, and if the melted hue of the purified phenol is 5 APHA or less, the hue of bisphenol A obtained even if it adheres to the adduct crystals is not particularly deteriorated.

The adduct crystals have a flow rate of 30 in the DSC measurement.
A sample volume of 6 to 10 mg was collected in an aluminum pan under a nitrogen atmosphere at 9 ml / min and heated at a heating rate of 10 ° C./min to obtain 9
Melt at 8 ° C to 105 ° C. Further, when the mixture of bisphenol A and the adduct crystal was heated at a temperature rising rate of 10 ° C./minute, the adduct crystal portion melted at 95 ° C. to 105 ° C.
Crystals of bisphenol A melt at 10 ° C to 160 ° C. The melting onset temperature of bisphenol A is lower as the phenol content in the mixture is higher because of the melting point lowering caused by phenol. On the contrary, if the phenol content in the mixture is low, the melting onset temperature of bisphenol A becomes high.

The heating method may be indirect heating, or, in the case of circulating an inert gas, direct heating or indirect heating in which the inert gas is heated and brought into contact therewith.
As the inert gas, helium, nitrogen, argon, etc.,
A gas having no reactivity with bisphenol A at the processing temperature is used, but nitrogen is generally used.

The dephenol temperature is in the range of 50 ° C. to 153 ° C., at a constant temperature, or at a constant temperature, if the adduct crystals and the mixture of bisphenol A and adduct crystals can remain solid. A heating program may be set up as the content decreases. When the adduct crystal and the mixture of the bisphenol A and the adduct crystal cannot maintain the solid state,
Phenol evaporation area is reduced, and the deterioration of coloring due to increased contact with the inner wall of the dryer is considered, and in the case of dephenoling by inert gas flow, the porosity of the mixture is lowered and the inert gas is reduced. Is difficult to distribute, and the dephenoling rate becomes slow, which is not preferable.

Practically, the temperature is 50 to 98 ° C. until the weight fraction of bisphenol A in the solid reaches 0.94.
Range, preferably 70 ° C. or higher, more preferably 8
It is preferable to dephenol at 0 ° C. to 95 ° C. and dephenol at 98 ° C. or higher after the weight fraction of bisphenol A reaches 0.94. Further, after the weight fraction of bisphenol A becomes 0.99 or more, the temperature is set to 145 to 153 ° C. The amount of phenol is 100 pp while keeping the solid state.
It is particularly preferable because dephenoling can be efficiently performed up to m or less.

The temperature after the weight fraction of bisphenol A in the solid reaches 0.94 is the critical temperature (T) at which the adduct crystal or the mixture of bisphenol A and the adduct crystal remains in the solid state. ℃) or less, depending on the heating method, T-3
It is preferable to dephenol at ℃. The limit temperature T varies depending on the weight fraction (X) of bisphenol A, T = -10
Represented by ^{2947 + 312220X-315850X 2 + 106730X} 3.
A glass tube in which an adduct crystal or a mixture of bisphenol A and an adduct crystal is enclosed in an oil bath in about 1/3 of a glass tube having an inner diameter of about 0.9 mm, an outer diameter of about 1.4 mm and a length of about 75 mm. FIG. 1 shows the results of measuring the weight fraction (X) of bisphenol A and the dephenol delimitation temperature when the temperature was raised from room temperature.

When a temperature raising program is set up and the temperature is raised stepwise, the weight fraction of bisphenol A is 0.94 to
During 0.99, the dephenol temperature is 70 to 145 ° C., preferably 98 to 145 ° C., and 70 to 153 ° C., preferably 98 after the weight fraction of bisphenol A becomes 0.99 or more. ~ 153 ° C, more preferably 145 ~ 153 ° C
Therefore, it is preferable to dephenol. When a continuous heating program is set up, the temperature can be set as a function of the weight ratio (X) of the bisphenol A weight fraction based on the above equation. If the temperature is too low
It is not preferable because the speed is slow.

The dephenol is 0.05 kPa to 50 k
Pa, preferably under a pressure of 0.3 kPa to 10 kPa,
Alternatively, 1 kPa to 500 kPa, preferably 6 kPa
It is carried out under an inert gas flow pressure of 300 kPa.
Generally, from normal pressure to increased pressure or under inert gas flow pressure.
Is preferred. When using an inert gas, contact the adduct crystal
The flow rate and contact time of the inert gas to be touched depend on the phenol content.
Depending on quantity, temperature, contact method, etc.,
When using a fluidized bed dryer, the flow rate is 1
m²2 to 5000 Nm ³/ Hour, preferably 20 to
3000 Nm³/ Hour, the contact time depends on the phenol content
The shorter the temperature, the higher the temperature, and the higher the flow rate, the shorter the time.
However, when the bed height when the fluidized bed is stationary is 0.1 m, it is 0.0
It is 5 minutes to 10 hours, preferably 0.2 minutes to 5 hours.
In the case of the continuous type, the dephenolization property is determined by preliminary experiments.
It is desirable to estimate and obtain the drying characteristic curve.

The dephenoling system may be a batch system or a continuous system, and in the case of a continuous system, a countercurrent operation or a cocurrent operation may be used. Specifically, various methods generally used for drying powders and granules can be applied, and for example, it can be performed by a box dryer, an aeration vertical dryer, a rotary dryer, a fluidized bed dryer, an airflow dryer, or the like. it can. The separated phenol is recovered by cooling, absorption, membrane separation, etc., and can be recycled and reused in the reaction system or crystallization system for the production of bisphenol A.

[0016]

The mechanism by which the dephenol is carried out from the adduct crystals by the method of the present invention is not clear, but from the results of differential thermogravimetric measurement (TG-DTA) and DSC measurement of the adduct crystals,
It is presumed that a crystal of bisphenol A alone grows as the crystal structure of the adduct crystal collapses and dephenol.
Furthermore, since the crystal growth of bisphenol A alone is relatively fast, it is considered that the sample exists in a solid state by appropriately controlling the amount of phenol and the temperature in the sample.

[0017]

According to the method of the present invention, since bisphenol A can be obtained by separating and removing phenol from the adduct crystal in a solid state in a short time, a process of removing phenol from the adduct crystal. Since the generation of the coloring-causing substance is reduced, it is possible to obtain bisphenol A having a high purity and a good hue.

[0018]

EXAMPLES Next, the present invention will be described more specifically by way of examples. In the examples,% means% by weight unless otherwise specified. The amounts of bisphenol A, phenol and impurities were quantified using high performance liquid chromatography. The hues of the adduct crystals and bisphenol A are values obtained by measuring a 50% ethanol solution with a spectrophotometer.

Example 1 1.5 mm in length and 0.3 m in width, manufactured by a known method.
m needle-like adduct crystals (hue: 5APHA, bisphenol A: 67.95%, phenol: 32.01%, other impurities: 0.04%) 5 g, diameter 10 mm, length 13
Packed in a 0 mm empty column (packing density 0.5 g / c
m ³ ), placed in a gas chromatography oven heated to 95 ° C., and passed helium gas at 180 ml / min for 5 hours. Supply pressure of helium gas is 200k in absolute pressure
It was Pa. The obtained bisphenol A has a purity of 9
9.93%, phenol content 0.009%, hue: 8
APHA and other impurities: 0.05%.

Example 2 Example 2 was repeated except that helium gas was passed at 180 ml / min for 1.5 hours. At this time, the phenol content was 3.06%. next,
Raise the oven temperature to 115 ° C and add helium gas to 18
Bisphenol A having a phenol content of 0.04% when flowing at 0 ml / min for 6 minutes and further increasing the temperature to 145 ° C. and flowing helium gas at 180 ml / min for 11 minutes had a purity of: The content was 99.94%, the phenol content was 0.007%, the hue was 12APHA, and the other impurities were 0.05%. No fusion of the sample was observed.

Example 3 In Example 1, 2 ml of helium gas was added at 180 ml / min.
The same procedure as in Example 1 was carried out except that the solution was distributed over time. The phenol content at this time was 0.02%. Next, raise the temperature of the oven to 145 ° C and add 180 ml of helium gas.
It was distributed for 11 minutes at a flow rate of 11 minutes. Obtained bisphenol A
Has a purity of 99.95% and a phenol content of 0.00
4%, hue: 10APHA, other impurities: 0.05%
Met.

Example 4 50 g of needle-shaped crystals similar to the additive used in Example 1 was put into a stainless steel bat so that the thickness was about 10 mm,
This was placed in a heating vacuum dryer for a laboratory. When the temperature of the heating vacuum dryer was set to 95 ° C. and the pressure was 1.33 kPa, the phenol content of this sample after 1 hour was 1
It was 2.2% and 0.018% after 2 hours. At this stage, the temperature of the heating vacuum dryer was raised to 145 ° C. while the pressure was 1.33 kPa, and the sample treatment was continued for another hour.
The obtained bisphenol A has a purity of 99.95%, a phenol content of 0.004%, a hue of 11APHA,
Other impurities: 0.05%.

Comparative Example 1 In Example 2, 180 ml of helium gas was added at 95 ° C.
Phenol content distributed for 3.0 hours at 3.06% per minute
A mixture of the bisphenol A and adduct crystals of
Raise the oven temperature to 145 ° C and add helium gas to 18
The same procedure as in Example 2 was repeated, except that the solution was flown at 0 ml / min for 20 minutes. As a result, the treated product was partially melted, and bisphenol A: 99.25%, hue: 15APHA, phenol content: 0.7%, and other impurities: 0.05%.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the weight fraction (X) of bisphenol A and the limit temperature (T ° C.) at which an adduct crystal or a mixture of bisphenol A and an adduct crystal maintains a solid state. It is a figure.

Front Page Continuation (72) Inventor, Takashi Sakita, Toho-cho, Yokkaichi-shi, Mie Prefecture Mitsubishi Chemical Co., Ltd. Yokkaichi Research Institute

Claims (5)

[Claims] 1. A bisphenol A which is obtained by dephenoling a crystal of an adduct of bisphenol A and phenol at a temperature of 50 ° C. to 153 ° C. while maintaining the solid state. Manufacturing method of A. 2. The method according to claim 1, wherein the weight fraction of bisphenol A in the adduct crystal is 0.5 to 0.71. 3. The method according to claim 1, wherein the dephenoling is carried out under an inert gas flow pressure. 4. Dephenolation at a temperature of 98 ° C. or lower until the weight fraction of bisphenol A in the solid reaches 0.94.
The method according to claim 1, wherein 5. The dephenol temperature is adjusted to 145 after the weight fraction of bisphenol A in the solid reaches 0.99 or more.
The method according to claim 1, wherein the temperature is not lower than ° C.