JPS5847407B2 - Polycondensation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polycondensation apparatus, particularly a polyester polycondensation apparatus.

Conventionally, polyester has been widely used as fibers, films, and certain types of products due to its excellent properties, and many proposals have been made regarding polyester manufacturing methods and manufacturing equipment.

In the process of producing polyester from terephthalic acid and ethylene glycol, the esterification reaction and polycondensation reaction are carried out continuously, either in a continuous process or in a batch process, depending on the purpose and scale, which are currently being carried out industrially. There is.

The batch manufacturing method is generally an extremely simple method and is relatively inexpensive if the equipment cost is small, and it is not only easy to manage the operation and maintenance of the equipment, but also suitable for small-lot, high-mix production. Although it has advantages such as ease of adjustment, it has been evaluated as being somewhat inferior to the continuous loading method in terms of product quality, particularly uniformity, product yield, etc.

However, such problems are not inherent defects in the batch method;
Rather, it simply reflects the deficiencies of conventional batch manufacturing methods and equipment.

In the conventional batch production method, a fixed amount of bis-2-hydroxyethyl terephthalate and/or its low polymer obtained by esterifying terephthalic acid and ethylene glycol or transesterifying terephthalic acid dialkyl ester and ethylene glycol is used. The mixture is supplied to the polymerization reaction tank, and after the supply is finished, the stirrer is started, and the pressure is gradually reduced in the polymerization reaction tank using a vacuum generator via a paper tube and a condenser to promote the polycondensation reaction.
After a certain period of time, the melt viscosity of the reaction liquid is estimated based on the torsional stress of the stirrer shaft or the power consumption of the electric motor, etc., and after reaching the target value, an inert gas is introduced into the reaction tank to break the vacuum and at the same time pressurize it to a predetermined pressure. Then, the valve of the extrusion die provided at the bottom of the reaction tank is opened, and generally, the blind plate attached to the bottom of the extrusion die is removed, and the reactant is taken out by the pressure of inert gas.

However, the lower part of the reaction tank, especially the piping leading to the extrusion die, is not stirred, so it is difficult to obtain a homogeneous polycondensation reaction product in the reaction tank, and unreacted products or heat-degraded products are likely to occur. .

In addition, it is difficult to accurately measure the viscosity when the viscosity is set by mechanical load on the stirrer shaft, and it is difficult to determine the end point of the polycondensation reaction.Also, after the reaction is complete, the reaction product is discharged by pressurizing an inert gas at the start and end points. However, there are also defects such as variations in the degree of polymerization.

Furthermore, although taking out the polycondensation reaction product without aggregates in the polycondensation process and sending it to the next process makes processes such as spinning and stretching smoother and improves the quality of the product, it cannot be done with conventional polycondensation equipment. Inserting a device is not normally practiced due to vacuum, pressurization, pressure resistance of the container, etc.

The inventors of the present invention completed the present invention as a result of various studies to eliminate the defects of the conventional art and solve the problems.

The purpose of the present invention is to prevent a decrease in yield due to the generation of degraded products, a change in the quality of the polycondensation reaction product between the start and end of dispensing, a contamination of foreign matter and insoluble matter, a change in the end point of the polycondensation reaction, etc. and to provide a polycondensation apparatus that is easy to operate.

The present invention relates to a polycondensation reaction tank having stirring and heating means, a circulation system extending from the lower part of the reaction tank to the middle part of the reaction tank via a liquid feed pump, a viscometer, a filter, and a three-way branch valve, and a vacuum in the reaction tank. This is a polycondensation device equipped with a regulating device.

The apparatus of the present invention will be explained below with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of a polycondensation apparatus of the present invention.

1 is a polycondensation reaction tank having a stirrer 2 and a heating jacket 3; the stirrer 2 generally has anchor type or helical ribbon type blades and is connected to a driving electric motor 4.

A take-out pipe 5 is attached to the lower part of the polycondensation reaction tank 1 and connected to a liquid sending pump 6.

Generally, a vertical or horizontal screw pump is used as the liquid pump 6, but a normal gear pump can also be used as long as the pump has excellent suction performance and sealing effect.

The circulation system is connected to the polycondensation reaction tank 1 via a circulation pipe 11 via a viscometer 8, a filter 9, a three-way branch valve 10.

The positions of the viscometer 8 and the filter 9 may be reversed.

The filter 9 may be made of wire mesh, sintered wire mesh, sintered metal, etc., but it is desirable that the filter 9 has the required furnace area and pressure resistance, and that the element can be easily regenerated.

Furthermore, if a liquid feeding valve 7 is connected to the take-out pipe 5, it is convenient to feed the polycondensation raw material.

Paper generated during the polycondensation reaction passes through a paper tube 12, a condenser 13, and a vacuum control valve 14 to the vacuum generator 1.
Processed by a vacuum regulator up to 5.

As the vacuum generator 15, either a steam ejector or a mechanical vacuum pump is used.

A pressure gauge 16 is attached to the discharge side of the liquid sending pump 6, and the liquid sending valve 7, viscometer 8, three-way branch valve 10, and vacuum control valve 14 are connected to the relay box 17, respectively, for liquid feeding, circulation, extraction, and vacuum adjustment. It will be more effective if they are linked together.

To give an example of the operation of the polycondensation apparatus of the present invention, after opening the liquid feeding valve 7 and supplying bis-2-hydroxyethyl terephthalate and/or its low polymer to the polycondensation reaction tank 1, the stirrer 2 and the vacuum The regulating device and the liquid feed pump 6 are started to stir and circulate the reaction liquid.

After detecting the end point viscosity with the viscometer 8, the three-way branch valve 10 is switched to liquid feed and the polymer is taken out.

The vacuum control valve is controlled to keep the viscosity constant during liquid feeding.

After the liquid feeding is finished and a drop in the pressure gauge is detected, the three-way branch valve 10 is switched to circulation, and the liquid feeding valve 7 is opened to start the next reaction.

According to the present invention, the polymer can be discharged from the polycondensation reactor while it is in a vacuum state using a liquid pump, and not only can polymers of extremely high quality and uniformity be obtained, but also polymers can be freshly supplied immediately after discharge. Since the reaction tank and circulation system are cleaned and the polymer is depolymerized using low-polymerization polymers, the yield of the product is greatly improved.

Furthermore, since the layout of the piping system can be freely arranged, it is also possible to centralize the discharge and chipping operations that were conventionally performed for each reaction tank, significantly increasing productivity.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a polycondensation apparatus of the present invention. In the figure, 1 is a polycondensation reaction tank, 2 is a stirrer, 3 is a heating jacket, 4 is an electric motor, 5 is an extraction pipe, 6 is a liquid pump, 7
is a liquid sending valve, 8 is a viscometer, 9 is a filter, 10 is a three-way branch valve, 11 is a circulation pipe, 12 is a paper pipe, 13
14 is a condenser, 14 is a vacuum control valve, 15 is a vacuum generator, 16 is a pressure gauge, and 17 is a relay box.

Claims (1)

[Scope of Claims] 1. A polycondensation reaction tank having stirring and heating means, a circulation system extending from the lower part of the reaction tank to the middle part of the reaction tank via a liquid feed pump, a viscometer, a filter, and a three-way branch valve; Polycondensation equipment equipped with a vacuum regulator for the reaction tank. 2. The device according to claim 1, wherein the circulation system is equipped with a pressure gauge. 3. The device according to claim 1, wherein a liquid sending valve is connected to the extraction pipe of the circulation system. 4. Claim 1 in which the vacuum regulating device is a combination of a paper tube, a condenser, a vacuum regulating valve, and a vacuum generator.
Apparatus described in section. 5 Liquid feeding valve, pressure gauge, viscometer installed in the circulation system,
Claim 1, in which a three-way branch valve and a vacuum control valve attached to a vacuum control device are connected and interlocked with a relay box.
Apparatus described in section.