JP2001294658A - Method for producing polycarbonate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polycarbonate by which the quality of a polycarbonate polymerized polymer product is improved and the equipment and operating costs are reduced. SOLUTION: This method for producing the polycarbonate comprises connecting two connected and horizontally placed cylindrical agitated tanks provided with even a part of an agitating element having screw functions in the continuously connected agitating element in a vessel without an agitation central shaft, using a uniaxial horizontal agitated tank rotating the agitating element ensuring the gap between the inner wall of the vessel and the agitating element of 1-50 mm and performing agitating treatment at a low speed within the range of 1 to 10 rpm in the first tank and using a two-shaft agitating element installed horizontally and parallel without a rotation central shaft and carrying out the agitating treatment at a low agitation number of revolutions of 1 to 15 rpm in the second tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate suitable for producing a polycarbonate by a transesterification method by using diphenyl carbonate and an alcohol such as bisphenol A as raw materials and mixing additives such as a reaction catalyst and a color tone agent. And a method for producing the same.

[0002]

2. Description of the Related Art In the method using a vertical stirring tank described on page 66 of "Polycarbonate Resin" published by Nikkan Kogyo Shimbun, as the equipment becomes larger, a large number of stirring tanks are required for continuous processing. Not a target.

[0003]

In order to make the apparatus economical, it is effective to use a horizontal stirring tank capable of holding many complete mixing tanks in the complete mixing tank row model.

In the Mechanical Engineering Handbook, C.I. Engineering C
The spectacle blade polymerization machine described in Fig. 2.49 (b) of 1-43 is a continuous stirring tank that can provide a large number of complete mixing tank rows and exhibits ideal extrusion flow characteristics, but has a high processing liquid viscosity. If so, the high-viscosity liquid adheres to the surface of the stirring central shaft and stays there, and a sharp residence time distribution function curve cannot be obtained.
This is shown by the delta response curve in FIG. This figure is experimental data showing the relationship between the number of model tanks in the complete mixing tank row and the residence time distribution function. In the spectacle wing polymerization machine, the dimensionless number of time t / to deviates from the theoretical curve when the value exceeds 1.3. This indicates that a part of the liquid is retained in the dead zone of the stirring. As a result, there arises a problem that the quality of the polymer is deteriorated.

[0005]

[Means for Solving the Problems] The lattice wing polymerization machine is Japanese Patent Publication 6
It is a stirring tank having no stirring center axis continuous with a rectangular frame described in JP-A-21159, and shows a curve along a theoretical value.

[0006] From this result, in order to continuously treat a high-viscosity liquid, a stirring blade having no stirring center axis has better mixing performance and contributes to improvement of the quality of the processing liquid. Therefore, in order to continuously produce polycarbonate by increasing the viscosity of the processing solution using alcohols such as diphenyl carbonate and bisphenol A as raw materials, it is necessary to use a horizontally installed cylindrical shape which is not provided with a stirring center axis. Connect one or more stirring tanks, 200 ℃
The polycondensation reaction is preferably carried out continuously at a high temperature in the range from 1 to 300 ° C. and in a vacuum at or below atmospheric pressure from 1 Pa · S to 5,000 Pa · S.

FIG. 9 shows experimental data comparing the mixing performance of various horizontal stirring tanks.

The greater the number of theoretical stages per unit stage, the better the mixing performance and the smaller the size of the apparatus, which is more economical. The uniaxial stirring tank in the figure is a stirring tank without a center axis of rotation and the stirring blades are continuously connected. The gap between the blade tip and the inner wall of the container is secured in the range of 1 mm to 50 mm over the entire inner surface of the container. ing. The results of this data indicate that the uniaxial stirring tank has more complete mixing tanks than the spectacle blade polymerization machine, and is superior in mixing performance. FIG. 10 also shows the mixing performance. When the viscosity is higher than 400 Pa · S to 600 Pa · S, the mixing performance of the spectacle blade is inferior to that of the lattice blade. From the experimental data shown in FIGS. 9 and 10, it can be seen that a horizontal stirring tank having no rotation center axis is more advantageous for treating a high-viscosity liquid from 1 Pa · S to 5,000 Pa · S.

[0009]

FIG. 1 shows an embodiment of a method for producing polycarbonate. In a continuous process produced by a transesterification method using diphenyl carbonate and bisphenol A as raw materials, the viscosity of the treatment liquid increases as the reaction proceeds. The prepolymer having a viscosity of 1 Pa · S or more obtained in the initial stage by the initial polycondensation reaction is continuously supplied to the first stirring tank 1 by the pump 6. As an example of the stirring tank, a stirring tank having a horizontal stirring tank having no stirring center axis as shown in FIGS. 2 to 7 may be used. Rotating shaft 19 on both sides
Are connected to an end plate 22, and both end plates are connected by several strength members 24. As the plurality of partition plates 10 to 13 provided perpendicularly to the strength member 24 and between the end plates 22 to prevent a short path in the longitudinal direction of the processing liquid having a different shape depending on the viscosity range of the processing liquid become higher in the high viscosity region. They are arranged at wide intervals. Reference numeral 12 denotes an intermediate plate.

The plate width of the stirring blades 15, 16, 17, 18 varies depending on the viscosity range of the processing solution, and the number of the blades attached varies over the circumference. Stirrer blade is 50 mm from inner wall of vessel
They are arranged continuously in the longitudinal direction while securing a small gap in the range of mm. The rotating shaft rotates at a low speed of 1 rpm to 10 rpm from 15 rpm to 20 rpm applied in the spectacle blade polymerization machine. As a result, the stirring power is reduced to several tenths. Scrape wings 20, 2 provided outside the end plates 22
Reference numeral 1 has a screw function of pressing the processing liquid inward while securing a slight gap with the inner wall of the tank body.

Approximately 1,000 discharged from the first stirring tank 1
The processing liquid having a viscosity of Pa · S is supplied to the second stirring tank 2 by the pump 6. The second stirring tank is 6-20115
No. 9 discloses a two-axis stirring tank provided with a continuous stirring blade having a continuous rectangular frame and having no stirring center axis and provided horizontally and in parallel. The reaction proceeds further in this reaction tank, and the viscosity of the processing liquid becomes as high as about 5,000 Pa · S, thereby producing a polymer.

The polycondensation reaction is performed in both stirring tanks at a high temperature in the range of 200 ° C. to 350 ° C. and in a vacuum in the range of atmospheric pressure to 0.1 Torr. Phenol, which is a reaction by-product, is vaporized and discharged from the upper part of the stirring tank, condensed in the condenser 4 and discharged to the outside of the system.

In another embodiment, the same type of the first stirring tank 1 as the second stirring tank 2 is used for the second stirring tank 2, and the shape of the partition plate and the interval between the partition plates are widened according to the viscosity range of the processing solution to form the partition plate. Deploy. As a result, it is possible to further reduce the stirring power.

[0014]

According to the present invention, the quality of the processing liquid can be improved by using a horizontal stirring tank having a continuous stirring blade having no rotation center axis. Further, it is possible to provide a polycarbonate production method capable of reducing equipment and operation costs.

[Brief description of the drawings]

FIG. 1 is a process schematic diagram showing one embodiment of a method for producing a polycarbonate according to the present invention.

FIG. 2 is a side view showing an example of a stirring blade structure of a first stirring tank.

FIG. 3 is a front view showing an example of a partition plate.

FIG. 4 is a front view showing an example of a partition plate.

FIG. 5 is a front view showing an example of a partition plate.

FIG. 6 is a front view showing an example of a partition plate.

FIG. 7 is a front view showing an example of a partition plate.

FIG. 8 is a mixing characteristic diagram showing an example of a delta response curve.

FIG. 9 is a characteristic diagram showing an example of a relationship between viscosity and the number of theoretical plates.

FIG. 10 is a characteristic diagram showing an example of a relationship between viscosity and mixability.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... 1st stirring tank, 2 ... 2nd stirring tank, 3 ... Stirrer without central axis of stirring, 4 ... Condenser, 5 ... Vacuum apparatus, 6 ... Pump, 7
... processing liquid passage piping, 8 ... vapor passage piping, 9 ... drive motor, 14 ... intermediate plate, 15-18 ... stirring blades, 19 ... rotating shaft, 20-21 ... scraping blades, 22 ... end plate, 23 ... opening , 24 ... strength member.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Seiji Motohiro 794, Higashi-Toyoi, Kazamatsu-shi, Yamaguchi Prefecture F-term in the Kasado Plant of Hitachi, Ltd. FJ-term (reference) LA12

Claims (1)

[Claims] An agitating and rotating apparatus comprising: a horizontal cylindrical container; and a hollow disk-shaped agitating blade continuously disposed in the container and connected at a position shifted from a center axis of rotation to an inner wall side of the container. A mixture of diphenyl carbonate and an alcohol such as bisphenol A is stirred and mixed by a uniaxial horizontal stirring tank provided with a screw section that pushes back the processing liquid inside the stirring blade closest to the container side wall without a shaft. A first step of processing, and a second step of stirring and mixing the mixed solution obtained from this first step with a horizontal twin-screw blade stirring tank. And performing a polycondensation reaction of the mixed solution under a vacuum at or below the atmospheric pressure to continuously produce polycarbonate by increasing the viscosity from 1 Pa · S to 5,000 Pa · S. Method of manufacturing the polycarbonate.