JPS6262906A - Extrusion apparatus of molten resin - Google Patents

Abstract

PURPOSE:To make the throughput from an extrusion head constant, by providing a pressure gauge near a branching point communicating from a connecting pipe between a vented extruder and an extrusion head to a polymer discharge means and controlling the amount to be discharged from the polymer discharging means according to the pressure. CONSTITUTION:An extrusion apparatus of a molten resin for feeding a melt of a mixture of a polymer with a monomer after continuous polymerization or a polymer melt, containing a small amount of a solvent and obtained by desolvating a polymer solution to a vented extruder 3, discharging the monomer or solvent from vent holes 4 and extruding the polymer from the connecting pipe 5 through a metering pump 7 and extrusion head 12. A branching passage 6 is provided in the course of the connecting pipe 5 to connect to the polymer discharging means 8 and a pressure sensor 9 is provided near a branching point 13. When the pressure sensor 9 detects that variation in extrusion through the extruder 3 becomes >=3%, the pressure in the connecting pipe 5, i.e. back pressure of the extrusion head 12, is kept constant by the polymer discharging means 8.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is applicable to continuous polymerization, demonomer removal, continuous spinning, and continuous spinning from a vent-ex 1-ruder while removing solvent from a polymer solution. The present invention relates to a molten resin extrusion device that discharges molten resin while suppressing fluctuations in the discharge amount.

(Prior art) The conventional method of melting a polymer chip with an extruder, metering it with a metering pump, and spinning it is well known, and the amount supplied from Ex1 to Ruder is controlled by the pressure of the extruder head. It was common to do so.

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 head pressure is controlled to be constant by increasing the supply amount. This method is easy and industrial when there is flexibility 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. Further, when discharging from such an extruder, the extruder had extremely good meterability, and even when discharging at a constant rotation without a metering pump, the variation in the discharge amount was about 3% or less.

On the other hand, in the case of a vented extruder, if the feed material is almost 100% polymer like chips,
It is similar to the extruder described above, but the raw material is generally a mixture of polymer/monomer, and the mixing ratio is 30 to 30.
In many cases, 9Qwt% is a polymer, and the seven components are extracted from this raw material, and 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 vapor pressure between the raw material and the polymer, which requires 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 extrusion constant. In addition, demonomer removal is performed under reduced pressure through several stages of vent holes, and the filling rate of polymer into the extruder changes each time, so the discharge amount essentially fluctuates to some extent.

Considering these things, it is not a good idea to change the rotational speed of the extruder 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 pelletization, the current situation is to find conditions that are reasonably stable and do not necessarily pay attention to it.

In general, 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 at a constant opening degree. However, this has the problem that although it is possible to reduce the average value of pressure, it is 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 problems) The structure of the present invention that achieves the above object is as follows.

That is, a communication pipe that connects 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 1 provided near the branch point between the branch path and the communication pipe. and 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 by 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.

The pen extruder 3 is heated to a temperature in the range of 100 to 300'C, and the vent hole 4 is reduced in pressure to a range of 10-3 to 760↑○rr for removal of monomer or solvent.

The demonomerized or desolventized polymer is sent to a spinning metering pump 7 and a spinneret 12 through a connecting pipe 5. On the other hand, the clad material melted by the extruder 24 is measured by the clad measuring gear pump 25, and
2 and is combined in the base 12.

A branch passage 6 is provided in the communication pipe 5. The polymer passing through the connecting pipe 5 is sent to a spinning metering pump 7 at a branch point 13.
A pressure sensor 9 is attached to the branch path 6 connected to the discharge means 8, and the polymer pressure is constantly detected. 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 due to large fluctuations in the discharge amount from the vent extruder can be suppressed. As this ejecting means, a needle valve that can change the opening degree of the ribbon channel according to a control signal, a gear pump, an extruder, etc. that can change the rotation speed can be used.

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 part, 14 is a connector, 1
5 is a resistance voltage converter, 16 is a connector, 17 is a pressure display,
The so-called P I RC (Pre
ssur, Indicator, Recorder
, Cont-r.

11er). 18 is an amplifier, 19 is an automatic control regulator, and 20 is a rotation detector and a tachogenerator. 21
2 is a pilot motor, and 22 is a driving motor, the driving 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 ventex 1 to router 3 and the spinning metering pump 7 is detected as a resistance change by the pressure sensor υ13, and the signal is 15
17 PIRC as voltage output by resistive voltage converter
is input. 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 the amplifier 18, where it is amplified and sent to the automatic control regulator 19. Sent.

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.
In the opposite case, the discharge amount is decreased and the pressure is increased to 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 amount of discharge from the extruder fluctuates widely, and furthermore, it is not necessary to spin polymers that can be spun 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 mixed into the core component during the process, and from this point of view continuous polymerization, layered spinning, and continuous spinning processes have been selected. Among these, the device of the present invention is extremely effective. In particular, MM, which is the main raw material for optical fiber,
A (methyl methacrylate) is subjected to continuous bulk polymerization to avoid dust contamination, and the remaining unreacted upper layer is collected in a layer by a demonomer machine, that is, a vent extruder 3, and is continuously sent to the spinning process to form a composite material. Spun. At this time, since the amount of polymer discharged from the vent extruder 3 varies considerably, it is effective to use the apparatus of the present invention.

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

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 3.3 kCI/hr, but when instantaneous fluctuations were included, the minimum and maximum discharge amounts were 2.7 to 3.5 kg/hr. .

When the device of the present invention is not used and a discharge hole with a constant opening degree is used, the primary pressure of the spinning metering pump is 50 to 1
It fluctuated to 30kQ/cm2. The polymer viscosity is high, over 10,000 poise, which affects the metering performance of the spinning metering pump, especially at low pressures, causing wire diameter fluctuations.
It was not possible to obtain yarn of stable quality.

In addition, for the safety of the head pressure of the vent extruder,
The upper limit pressure was set at 150 kg/cm2, but if there was a significant fluctuation, the upper limit pressure could be exceeded due to instantaneous pressure increase, and the vent extruder would stop. Therefore, a gear pump was used as the discharge means in the apparatus of the present invention, but although fluctuations from the vent extruder were still present, fluctuations in the discharge amount or pressure could be absorbed at the branch point of the apparatus of the present invention. Set pressure to 50kC]/C
m2, the pressure fluctuation detected by the pressure sensor is 0.
．． 6kg/cm2. ! = 1.2% (D change! 1. It was found that this corresponds even when there is a fairly rapid pressure change in the vent extruder. Because ≠, the vent extruder is There is no need to stop, and it is now possible to spin with a stable wire diameter.

Example 2 The set pressure of the pressure control device used in the present invention was set to 50 kcl/
Control is performed by setting Cm2, and the spinning head is simply
A single hole of z was installed and spinning was performed.

The pressure fluctuation in the control section is ±1. It became Okc+/cm2. Under these conditions, spinning was carried out at a take-up speed of 12 m/ml to obtain filaments of 0.5 mm and ff. As a result, the outer diameter variation was ±15μ or less. 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. Brief explanation of the drawings 1: Raw material storage tank or polymerization tank 3: Vent extruder 4: Vent hole 5: Connecting pipe 6: Branch path 7: Spinning metering pump

Claims (1)

[Claims] 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 the pressure sensor. A molten resin extrusion device comprising: an automatic control mechanism that controls the discharge amount of the discharge means using a sensor.