JPH0224923B2 - - Google Patents

Description

[Detailed description of the invention] {Industrial field of application} The present invention is applicable to continuous polymerization, demonomerization, continuous spinning,
The present invention relates to a molten resin extrusion device that discharges a polymer solution while suppressing fluctuations in the discharge amount from a vent extruder when continuous spinning is performed while removing the solvent from a polymer solution.

{Conventional technology} Conventionally, a polymer chip is melted with an extruder,
The method of metering and spinning using a metering pump is well known, and the amount supplied from the extruder has generally been controlled by the pressure of the extruder head.

In this method, if the supply amount is large, the head pressure will be high, and this signal will lower the extruder rotation speed to reduce the supply amount, and conversely, if the supply amount is small and the head pressure is low, the rotation speed will be increased. The supply amount is increased and the head pressure is controlled to be constant. This method is easy and industrial when there is a degree of freedom on the raw material supply side, such as when chips are supplied from a hopper, and an increase or decrease in the supply amount does not affect other processes. In addition, when discharging from such an extruder,
The metering performance of the extruder was extremely good, and even when the extruder was discharged at constant rotation without a metering pump, the discharge amount fluctuation was about 3% or less.

On the other hand, in the case of a vented extruder, when the raw material supplied is almost 100% polymer like chips, it is similar to the extruder described above, but in general, the raw material is a mixture of polymer/monomer, and The mixing ratio is often 30 to 90 wt% polymer, and monomer components are extracted from this raw material.
Only the polymer component or 99% or more of the polymer is sent to a spinning or discharging device. Therefore, the following restrictions arise in the operation of the vent extruder.

That is, the raw material is generally a viscous liquid, and it is quite difficult to control the supply amount due to problems such as the balance of monomer/polymer vapor pressure, such as heating for supply to the extruder. Further, when a certain amount of raw material is continuously supplied, it is necessary to operate the extruder under as constant conditions as possible in order to keep the amount of monomer removed constant. Also,
Demonomer removal is carried out under reduced pressure through several stages of vent holes, and since the filling rate of polymer into the extruder changes each time, it is essentially accompanied by a certain amount of discharge amount fluctuation.

Considering these points, it is not a good idea to change the extruder rotational speed depending on the head pressure in order to suppress variations in the discharge amount of the vent extruder. Therefore, efforts are generally made to find a method for supplying raw materials with as much polymer component as possible and to find the most stable optimum value in terms of conditions. Furthermore, in the case of discharging for purposes such as pelletizing, the current situation is to find conditions that are reasonably stable and do not take much care.

Furthermore, if large fluctuations in the discharge amount are expected or to prevent sudden accidents, a safety valve or valve is installed in the communication pipe between the extruder and the spinning section, and the polymer is discharged with a constant opening degree. However, this method had the problem that although it was possible to reduce the average value of pressure, it was not possible to reduce the fluctuation itself.

{Problems to be Solved by the Invention} An object of the present invention is to provide an apparatus that continuously feeds the polymer that has been demonomized or desolvated using the vent extruder described above to a spinning process, meters it, and spins it. When the discharge amount from the vent extruder fluctuates greatly, by suppressing the fluctuation, it prevents an adverse effect on the vent extruder, and at the same time controls the primary pressure of the metering pump of the spinning device to a constant level. This stabilizes metering performance and prevents mechanical damage.Also, by keeping the back pressure of the spinning device constant, it is possible to perform spinning without using a metering pump. The present invention aims to provide a resin extrusion device.

{Means for solving the problems} The configuration of the present invention that achieves the above object is as follows. That is, a communication pipe connecting the vent extruder and the discharge head, a branch path provided in the communication pipe leading to the polymer discharge means, and a pressure sensor provided near the branch point between the branch path and the communication pipe, The apparatus for extruding molten resin is characterized by having an automatic control mechanism that controls the discharge amount of the discharge means using the pressure sensor.

Then, the present invention uses the above-mentioned extrusion device to supply the monomer/polymer mixture or polymer solution after continuous polymerization to a vent extruder, remove the monomer or solvent, and then continuously spin the polymers. In the process of sending liquid to the process, when the discharge amount from the extruder fluctuates by 3% or more, the pressure inside the connecting pipe, that is, the back pressure to the spinning head, is kept constant using the polymer discharge means that follows the branch path provided in the connecting pipe. It was designed to control the

EMBODIMENT OF THE INVENTION Hereinafter, the extrusion apparatus of this invention is demonstrated based on one Example shown in drawing.

FIG. 1 is a schematic diagram showing an embodiment of the apparatus of the present invention.

In the figure, 1 is a raw material storage tank, and in the case of continuous polymerization, this part becomes a polymerization tank. In that case, monomers and catalysts are metered and fed to this polymerization tank. The raw material, which may be a monomer/polymer mixture or a polymer solution, is continuously supplied to the vent extruder 3 by a metering pump 2.

In the Ben extruder 3, the temperature is heated in the range of 100 to 300°C, and the vent hole 4 is reduced in pressure to 10 ^-3 to 760 torr for removal of monomer or solvent.
The demonomerized or desolventized polymer is sent through a connecting pipe 5 to a spinning metering pump 7 and a spinneret 12 which is a discharge head. On the other hand, the crud material melted by the extruder 24 is measured by the crud measuring gear pump 25, and the crud material is measured by the crud metering gear pump 25.
2 and is combined in the base 12.

A branch passage 6 is provided in the communication pipe 5. The polymer passing through the communication pipe 5 branches into the spinning metering pump 7 and the polymer discharge means 8 at the branch point 13, and flows into the spinning metering pump 7 and the polymer discharge means 8. A pressure sensor 9 is attached to the branch passage 6 connected to the discharge means 8, and the polymer pressure is constantly monitored. Detection is performed. This detected signal becomes a rotational speed adjustment signal for the drive motor 11 of the ejecting means 8 in the signal converter and regulator 10, and actually controls the rotational speed of the drive motor 11.

In the control method, a reference polymer pressure is set by the signal converter and regulator 10, and if the detected pressure is higher than the reference polymer pressure, a speed increase signal is issued to the drive motor of the discharge means 8, and the rotation speed is increased. becomes larger, increasing the amount of polymer discharged and lowering the pressure inside the pipe. On the other hand, if the detected pressure is lower than the reference pressure, the drive motor 11 is decelerated to reduce the discharge amount and increase the polymer pressure in the pipe to approach the reference pressure.

By controlling the pressure in the communication pipe to be constant in this manner, the metering performance of the spinning metering pump is always kept constant, and pressure fluctuations caused by large fluctuations in the discharge amount from the vent extruder can be suppressed. This evacuation means includes a needle valve that can change the opening of the pump flow path using a control signal;
Alternatively, a gear pump, extruder, etc. that can change the rotation speed can be used. In addition, connecting pipe 5
Although the case where there is one spinning metering pump 7 and one spinneret 12 on the discharge part side is shown, there may be a plurality of them.

Next, FIG. 2 shows an example of the circuit of the pressure control mechanism used in the present invention.

In the figure, 9 is a pressure sensor section, 14 is a connector, 15 is a resistance voltage converter, 16 is a connector, 1
7 is a pressure display, recording and control device, so-called
PIRC (Pressur, Indicater, Recorder, Cont−
roller). 18 is an amplifier, 19 is an automatic control regulator, and 20 is a rotation detector and a tachogenerator. 21 is a pilot motor, and 22 is a drive motor, the drive shaft of which is connected to the polymer discharge means to drive it. 23 is a power source.

In this device, the pressure in the communication pipe 5 that connects the vent extruder 3 and the spinning metering pump 7 is detected as a resistance change by the pressure sensor 13, and the signal is output as a voltage by the 15 resistance voltage converter. Input into PIRC. here,
The set pressure and the continuously sensed pressure are compared and, if there is a difference, a voltage output proportional to the difference is sent to an amplifier 18 where it is amplified and sent to the automatic control regulator 19.

The output from the automatic control regulator 19 rotates a pilot motor for changing the opening degree or rotational speed of the polymer discharging means, thereby changing the discharge amount. That is, if the detected pressure is higher than the set pressure, the opening of the discharge means is increased or the rotational speed is adjusted to increase the amount of polymer discharged and the pressure is lowered, and vice versa. Decrease the discharge volume, increase the pressure, and adjust to the set pressure.

Now, there are no particular restrictions on the raw materials such as polymers that can be handled by the apparatus of the present invention, but as mentioned above, they are not necessary for spinning polymers that can be chip-spun, and the discharge amount from the extruder fluctuates widely, and furthermore, it is not necessary to spin the polymer continuously. This method is effective when precise spinning is required.

The quality of the optical fiber obtained by composite spinning is greatly affected by the dust that is mixed into the core component during the process, and from this point of view continuous polymerization, demonomer removal, and continuous spinning processes have been selected. Among these, the device of the present invention is extremely effective. especially,
MMA (methyl methacrylate), the main raw material for optical fiber, is continuously polymerized in bulk to avoid dust contamination, and the remaining unreacted monomer is removed by a demonomer machine, namely vent extruder 3, and then continuously spun. It is sent to a process where it is spun into composite fibers. At this time, since the amount of polymer discharged from the vent extruder 3 varies considerably, the use of the apparatus of the present invention is effective.

Although the above description has been made regarding yarn spinning, it goes without saying that the invention can also be applied to melt extrusion devices for films, plastics, etc.

Example 1 Continuous bulk polymerization was carried out using a monomer having a single composition of MMA and a conventional catalyst, and then the solution was continuously fed to a vent extruder to remove the monomer. The average discharge amount from the demonomer machine at this time was 3.3Kg/hr.
However, when including momentary fluctuations, it was 2.7~
It showed a minimum and maximum discharge amount of 3.5Kg/hr.

When the device of the present invention is not used and a discharge hole with a constant opening degree is used, one of the metering pumps for spinning
The next pressure varied from 50 to 130 Kg/ ^cm2 . Because the polymer viscosity is as high as 10,000 poise or more, it affected the metering performance of the spinning metering pump, especially at low pressures, causing wire diameter fluctuations and making it impossible to obtain yarn of stable quality.

In addition, to ensure the safety of the head pressure of the vent extruder, the upper limit pressure was set at 150 kg/cm ² , but if there is a large fluctuation, the pressure will rise momentarily, exceeding the upper limit pressure and the vent extruder will stop. It was hot. Therefore, in the apparatus of the present invention, a gear pump was used as the discharge means, but although there were still fluctuations from the vent extruder, the fluctuations in discharge amount or pressure could be absorbed at the branch point of the apparatus of the present invention. When the set pressure is 50Kg/ ^cm2 , the pressure fluctuation detected by the pressure sensor is 0.6Kg/cm2.
cm ² and a variation of 1.2%. It was found that this was possible even when there was a fairly rapid pressure change in the vent extruder. Therefore, the vent extruder does not stop when the pressure exceeds the upper limit, and spinning with a stable wire diameter becomes possible.

Example 2 The set pressure of the pressure control device used in the present invention was set to 50
Control was performed by setting the spinning head to Kg/cm ² , and a single hole of 2φ was simply attached to the spinning head to perform spinning.

The pressure fluctuation in the control section was ±1.0Kg/cm ² .
To obtain a filament of 0.5mmφ under these conditions
Spinning was carried out at a take-up speed of 12 m/min. the result,
The outer diameter variation was less than ±15μ. It has been found that the apparatus of the present invention is also applicable to spinning without directly using a metering pump.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the apparatus of the present invention. FIG. 2 is a circuit diagram showing one embodiment of the pressure control mechanism used in the device of the present invention. Explanation of symbols in the drawings: 1: raw material storage tank or polymerization tank, 3: vent extruder, 4: vent hole, 5: connecting pipe, 6: branching path, 7: spinning metering pump, 8: polymer discharge means, 9: Pressure sensor, 12: Spinneret, 13: Branch point.

Claims (1)

[Claims] 1. A communication pipe connecting the vent extruder and the discharge head, a branch path provided in the communication pipe leading to the polymer discharge means, a pressure sensor provided near the branch point between the branch path and the communication pipe, and A molten resin extrusion device comprising: an automatic control mechanism that controls the discharge amount of the discharge means using a pressure sensor.