JP2001040520A - Method for exchanging shaping nozzle, and apparatus for shaping molten resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for exchanging a shaping nozzle by which the shaping nozzle of a shaping device of a molten resin can be readily exchanged, and the lowering of productivity accompanied by the exchange of the shaping nozzle can be prevented, and further to provide an apparatus for shaping the molten resin, suitable for the method. SOLUTION: When exchanging a shaping nozzle 3 of a shaping apparatus of a molten resin, having an extruder 5, the shaping nozzle 3, a resin-discharging means and a resin passage from the extruder 5 to the shaping nozzle 3 and the resin-discharging means, the shaping nozzle 3 is exchanged while discharging the whole resin extruded by the extruder 5 from the resin-discharging means. The shaping apparatus has the extruder 5, the resin-discharging means, plural shaping nozzles 3, and the resin passage from the extruder 5 to each of the shaping nozzles and the resin-discharging means, and the resin passage is constituted of a connecting pipe connecting the extruding opening of the extruder 5 and the resin-discharging means, and plural branched passages 10 arranged at the intermediate of the connecting tube and communicating with the plural shaping nozzles 3, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for exchanging a molding nozzle of a molding apparatus for molten resin and a molding apparatus suitable for the method.

[0002]

2. Description of the Related Art As an apparatus for shaping a molten resin extruded from a devolatilizing extruder using a shaping nozzle, for example, Japanese Patent Publication No. Hei 2-24923 discloses that a vent extruder and a discharge head are connected. An apparatus for extruding a molten resin having a connecting pipe and a branch path leading to a polymer discharging means provided in the connecting pipe is disclosed.

[0003] As a product manufactured using such a method, for example, it is used for lighting such as an optical display and for short-distance light transmission because of its large diameter, light weight, and excellent workability and workability. In recent years, there is a plastic optical fiber whose demand is increasing in recent years. Plastic optical fibers can be approximately 120 μm to 300 μm, depending on the application.
Since a fiber having a very wide diameter of 0 μm is used, and it is difficult to manufacture an optical fiber having such a wide diameter using the same spinning nozzle, a spinning nozzle suitable for the yarn diameter is used. Had to be replaced and manufactured.

[0004]

Incidentally, when manufacturing a plastic optical fiber having excellent optical characteristics, as disclosed in Japanese Patent Publication No. 53-42260 and Japanese Patent Publication No. 5-32722, continuous A polymer obtained by continuously separating volatile components from a mixture of a polymer and a monomer produced by bulk polymerization or continuous solution polymerization using a devolatilizing extruder is directly led to a composite spinning nozzle to be spun. The method has been adopted. However, when replacing the spinning nozzle for the kind change in such a continuous manufacturing process,
Since it is necessary to temporarily stop a process before spinning such as a devolatilizing extruder, there is a problem that productivity is extremely reduced.

[0005] An object of the present invention is to easily replace a shaping nozzle when replacing a shaping nozzle of an apparatus for shaping a molten resin extruded from a devolatilizing extruder using a shaping nozzle. It is an object of the present invention to provide a method of exchanging a shaping nozzle that can be performed and prevent a decrease in productivity due to the exchanging of a shaping nozzle, and a molten resin shaping apparatus suitable for the method.

[0006]

SUMMARY OF THE INVENTION The gist of the present invention is to provide an extruder, a shaping nozzle, a resin discharging means, and a molten resin shaping apparatus provided with a resin flow path from the extruder to the shaping nozzle and the resin discharging means. In exchanging the shaping nozzle, the extruder is operated, and the shaping nozzle is replaced while discharging all of the resin extruded from the extruder from the resin discharging means.

Further, the gist of the present invention is to provide an extruder, a resin discharging means, a plurality of shaping nozzles, and a molten resin forming apparatus having a resin flow path from the extruder to each shaping nozzle and the resin discharging means. In the forming device, the resin flow path is formed from a communication pipe that communicates the extrusion port of the extruder and the resin discharge means, and a plurality of branch paths that are arranged in the middle of the communication pipe and communicate with the plurality of shaping nozzles. There is a configured molten resin shaping device.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, as an embodiment of the present invention, a method for exchanging a shaping nozzle and a shaping apparatus for molten resin according to the present invention are described as a plastic optical fiber having a core-sheath structure (hereinafter simply referred to as an “optical fiber”). ) Will be described. The present invention is particularly suitable for manufacturing an optical fiber, but is not limited to this, and can be used in a manufacturing process of another shaped body.

In the present invention, a molding apparatus having a resin discharge means in a resin flow path from an extruder to a molding nozzle is used as a molding apparatus for molten resin. FIG. 1 is a schematic diagram showing an example of such a shaping device. During the production of the optical fiber, a polymer composition for a core material containing a volatile component such as a monomer which is continuously polymerized and partially obtained as a raw material by a polymerization apparatus not shown, It is continuously supplied to a devolatilizing extruder 1 as an extruder to separate and remove volatile components. The polymer obtained by separating and removing the volatile components is extruded from the tip (extruding port) of the devolatilizing extruder 1, and a part of the polymer is discharged from the polymer discharging port 8 as a resin discharging means through the connecting pipe 6. Is done. A part of the polymer extruded from the devolatilizing extruder 1 is supplied to the gear type metering pump 2 through a branch 10 branched from a branch point 9 provided in the communication pipe 6, and the gear of the gear type metering pump 2 is provided. After the amount necessary for the spinning is measured by the rotation of, it is sent as a core material to the inner layer of the spinning nozzle 3 which is a shaping nozzle through the branch path 10. That is, from the devolatilizing extruder 1 to the spinning nozzle 3 and the polymer outlet 8
Is provided between the devolatilizing extruder 1 and the polymer outlet 8 and a connecting pipe 6 in the middle thereof.
And a branch 10 leading to A pressure sensor 11 and a pressure adjusting mechanism 7 are provided between the branch point 9 and the polymer outlet 8, and the pressure adjusting mechanism 7 detects a pressure in the communication pipe 6 detected by the pressure sensor 11, The pressure in the communication pipe 6 is adjusted so as to maintain a suitable pressure for securing the quantitativeness of the gear type metering pump 2. On the other hand, the polymer for the sheath material is separately melted by the extruder 5, measured by the gear type metering pump 4, and sent to the outer layer of the spinning nozzle 3 as the sheath material. The core material and the sheath material sent to the spinning nozzle 3 are stacked concentrically in the spinning nozzle 3, and an optical fiber having a core-sheath structure is spun.

When replacing the spinning nozzle 3, the gear type metering pump 2 is stopped, and the entire polymer is discharged from the polymer outlet 8. Therefore, the spinning nozzle 3 can be replaced without stopping the process of polymerizing the monomer or separating and removing the volatile component by the devolatilizing extruder 1, and stopping the polymerization apparatus and the devolatilizing extruder 1 The time and labor required for starting operation is saved, and the productivity of optical fibers is improved. In addition, when the polymerization apparatus and the devolatilizing extruder 1 are stopped in the manufacturing process of the core material of the optical fiber, deteriorating substances and the like are generated in the pipes and the apparatus during the stop, and the deterioration occurs when the operation is started again. The substance is mixed into the polymer for the core material, and the transparency of the polymer is reduced. for that reason,
When the polymerization apparatus and the devolatilizing extruder 1 are temporarily stopped during the production of the optical fiber, it is possible to obtain an optical fiber having the same transparency as before the replacement of the spinning nozzle 3 unless the operation is continued for a long time. No, productivity is reduced. In the present invention, since the spinning nozzle 3 can be replaced without stopping the polymerization apparatus and the devolatilizing extruder 1, the spinning nozzle 3 can be replaced.
After the replacement of the spinning nozzle 3, it becomes possible to produce an optical fiber having the same light transmission performance as before the replacement of the spinning nozzle 3 in a short time,
The productivity of the optical fiber can be improved.

In the present embodiment, the polymer outlet 8 is provided only in the resin flow path for the core material, and the spinning nozzle 3 is replaced while discharging the resin extruded from the devolatilizing extruder 1. However, the resin flow path for the sheath material is designed in the same manner as the resin flow path for the core material, and the spinning nozzle 3 is replaced while performing the same processing as that described for the core material on the sheath material. Is also possible.

In the present embodiment, in order to improve the quantitativeness of the gear type metering pump 2 and reduce the unevenness in the amount of resin discharged from the spinning nozzle 3, one of the resins extruded from the devolatilizing extruder 1 is used. When the optical fiber is spun while adjusting the pressure in the connecting pipe 6, the unevenness in the amount of resin discharged from the spinning nozzle 3 does not cause much problem. Instead of discharging the resin from the polymer outlet 8, all of the resin extruded from the devolatilizing extruder may be sent to the spinning nozzle 3 for spinning.

Hereinafter, each part will be described in more detail.
As the polymerization apparatus, a known polymerization pot or the like is used. In order to improve the productivity of the optical fiber, it is preferable that the polymerization is continuously performed and the obtained polymer composition is continuously supplied to the devolatilizing extruder 1, and the polymerization is performed by bulk polymerization, solution polymerization, or the like. Is preferred.

Known devolatilizing extruders 1 and 5 are used. In this embodiment, since it is necessary to remove volatiles from the polymer composition supplied to the extruder for the core material, the devolatilizing extruder 1 is used as the extruder, Since a polymer is supplied to the extruder and the need to remove volatiles is low, a normal screw-type extruder is used as the extruder 5. Examples of the devolatilizing extruder 1 include JP-B-52-17555 and JP-A-59-15555.
An extruder provided with a vent portion for separating and removing volatiles under reduced pressure as described in JP-A-133206 or JP-A-2-49005 is used.

As the spinning nozzle 3, a known composite spinning nozzle or the like is used. It is also possible to distribute the resin to a plurality of flow paths in one spinning nozzle 3 and spin a plurality of optical fibers from one spinning nozzle 3, but the resin is distributed due to uneven distribution of the resin to each flow path. The number of optical fibers spun from one spinning nozzle is preferably 20 or less in order to reduce unevenness in the discharge amount of the resin, and it is necessary to control the discharge amount of the resin from the spinning nozzle 3 with higher accuracy. In this case, it is more preferable to spin one optical fiber per spinning nozzle without distributing the resin in the spinning nozzle 3. The number of spinning nozzles 3 is not particularly limited,
In order to improve the productivity of optical fibers, it is preferable to use a plurality of optical fibers.

As the connecting pipe 6 and the branch path 10, a known pipe such as a metal pipe is used. The number of the branch paths 10 is preferably the same as the number of the spinning nozzles, and it is preferable that each of the spinning nozzles is arranged in one branch path 10, respectively.
It is also possible to further provide a resin flow path branched from the branch path 10, and to arrange a plurality of spinning nozzles 3 for one branch path 10.

When a plurality of spinning nozzles 3 are used, the polymer outlet 8 can be disposed between the devolatilizing extruder 1 and the branch point 9, and the branch point 9 adjacent to the branch point 9 can be disposed. Although it is also possible to arrange between the spinning nozzles, the stagnation portion of the polymer when replacing the spinning nozzle 3 is reduced as much as possible,
In order to prevent generation of degraded products as much as possible, it is preferable to provide a branch point 9 between the devolatilizing extruder 1 and the polymer outlet 8 as in the above embodiment. With such a configuration, only the branch passage 10 remains in the polymer when the spinning nozzle 3 is replaced, and the polymer staying portion can be reduced. For this reason, it is possible to further shorten the time after the replacement of the spinning nozzle 3 until it becomes possible to produce an optical fiber having the same light transmission performance as before the replacement of the spinning nozzle 3, thereby further improving the productivity of the optical fiber. Can be done. In this case, the distance from the branch point 9 to the spinning nozzle 3 (the length of the branch path 10) is preferably as short as possible in order to further reduce the staying portion of the polymer. Branch road 10
The length of the molten resin during the spinning of the optical fiber,
The time from the branch point 9 to the spinning nozzle 3 is set so as to be preferably 20 minutes or less, and more preferably 10 minutes or less.

Although a needle valve is used as the pressure adjusting mechanism 7 in the present embodiment, a known device having a function of maintaining the pressure in the communication pipe 6 can be used.
For example, a ball valve, a gear type metering pump, an extruder and the like can be used. Further, it is preferable that the pressure adjusting mechanism 7 has a function of automatically controlling the pressure in the communication pipe 6. In the present invention, when exchanging the spinning nozzle 3 as described above, all of the polymer extruded from the devolatilizing extruder 1 is sent to the polymer outlet 8. At this time, the flow rate of the discharged polymer greatly changes from the flow rate during the production of the optical fiber, so that the pressure in the connecting pipe 6 also greatly changes. For this reason, in some cases, the pressure in the communication pipe 6 is increased by the devolatilizing extruder 1.
, Or the allowable pressure of the gear type metering pump 2. Since the pressure adjusting mechanism 7 automatically adjusts the pressure in the communication pipe 6, it is possible to prevent the devolatilizing extruder 1 and the gear type metering pump 2 from being deteriorated due to excessive pressure. The pressure adjusting mechanism 7 automatically adjusts the pressure in the communication pipe 6 so that the pressure in the communication pipe 6 during the production of the optical fiber is increased.
By reducing the pressure fluctuation in the inside, the quantitativeness of the gear type metering pump 2 can be improved, and the unevenness in the diameter of the optical fiber can be reduced.

For automatically adjusting the pressure in the connecting pipe 6
For example, as in the present embodiment, the pressure sensor 1
Pressure adjustment according to the pressure in the connecting pipe 6 detected by 1
A method of controlling the mechanism 7 is given. Specifically, the pressure
If a needle valve is used as the adjustment mechanism 7,
If a gear pump is used, adjust the opening of the gear pump.
When using an extruder, set the number of revolutions to
The rotation speed of the feeder is adjusted according to the pressure in the communication pipe 6.
And In addition, the communication pipe 6 detected by the pressure sensor
Manually adjust the pressure adjusting mechanism 7 according to the internal pressure.
Both are possible. Also, as the pressure adjusting mechanism 7,
A spring is provided to automatically adjust the pressure applied to the valve.
Needle having a structure in which valve opening is dynamically adjusted
When the valve is adopted, the pressure in the pressure sensor 11 and the connecting pipe 6 is reduced.
Complex control for controlling the pressure adjusting mechanism 7 according to the force
This is preferable because a circuit is not required. Pressure in connecting pipe 6
At the time of spinning and when replacing the spinning nozzle 3
Also, 10 to 200 kg / cm ^TwoPreferably in the range
New Used for devolatilizing extruder 1 if the pressure in the connecting pipe is too low
Devolatilizing extruder does not rotate stably
The screw is worn due to the screw contact with the inner wall of 1
There is a possibility that
Optical fiber spun with less stable pump output
There is a possibility that unevenness in yarn diameter may occur. In addition, the pressure in the connecting pipe 6
If the power is too high, the screw of the devolatilizing extruder 1 will not be stressed.
And the pressure exceeds the buckling strength of the screw.
The screw may bend if it gets on the screw.
You. When spinning the optical fiber, the devolatilizing extruder 1
Heat is generated at the tip of the screw.
The fat deteriorates and the light transmission performance of the resulting optical fiber decreases.
May be affected.

As the polymer for the core material used in the production of the optical fiber, a known polymer is used, and a homopolymer of methyl methacrylate having excellent transparency or a copolymer containing methyl methacrylate as a main component is preferably used. . Other copolymerization components to be copolymerized with methyl methacrylate include alkyl (meth) acrylate, benzyl methacrylate, fluoroalkyl methacrylate and the like.

As the polymer for the sheath material, a known polymer is used. For example, a polymer of vinylidene fluoride and fluoroalkyl vinyl ether, methacrylate, acrylate, tetrafluoroethylene, hexafluoropropene, or vinyl acetate is used. Copolymers and the like can be used. Further, a copolymer of a fluoroalkyl (meth) acrylate and a methacrylic acid ester or an acrylic acid ester can also be used. Preferable examples include a polymer mainly containing vinylidene fluoride and a polymer mainly containing fluoroalkyl methacrylate. As the polymer containing vinylidene fluoride as a main component, for example, a copolymer of vinylidene fluoride and tetrafluoroethylene containing 75 to 99% by weight of vinylidene fluoride, 75 to 95% by weight of vinylidene fluoride and tetrafluoroethylene 4 ~ 20% by weight and hexafluoropropene 1
10 to 10% by weight of a copolymer, vinylidene fluoride 7
Copolymers of 5 to 95% by weight, 4 to 20% by weight of tetrafluoroethylene and 1 to 5% by weight of vinyl fluoride are exemplified. Examples of the polymer containing fluoroalkyl methacrylate as a main component include a copolymer of short-chain fluoroalkyl methacrylate, a long-chain fluoroalkyl methacrylate and methyl methacrylate, and a copolymer containing methacrylic acid as a copolymer component of the copolymer. Coalescing,
Examples include a copolymer of methyl methacrylate, long-chain fluoroalkyl methacrylate and methacrylic acid.

[0022]

The present invention will be described in more detail with reference to the following examples, which do not limit the present invention.

Example 1 As a polymer composition, a polymer content of 42 obtained by bulk polymerization of methyl methacrylate in the presence of a polymerization initiator and a mercaptan-based chain transfer agent was obtained.
The composition was continuously supplied to the devolatilizing extruder 1 to continuously extrude the polymer from which volatile components were removed. The connecting pipe 6 is provided with three branch points 9 and the devolatilizing extruder 1
The polymer extruded from is measured by the gear type metering pump 2 connected to each branch 10 so as to have a flow rate of 2 liter / hr, and the polymer is supplied to the inner layer of the spinning nozzle 3 having a two-layer structure as a core material. Supplied. The remaining polymer was discharged from the polymer outlet 8. A needle valve is used as the pressure adjusting mechanism 7, and the pressure in the connecting pipe 6 is detected by the pressure sensor 11.
The opening of the needle valve was adjusted so that the pressure of the connecting pipe became 50 kg / cm ^{2 on} average. On the other hand,
A polymer of 2,2-trifluoroethyl methacrylate was melted by an extruder 5 and measured by a gear type metering pump 4.
It was fed to the outer layer of the composite spinning nozzle. The temperature of the spinning nozzle 3 was set to 210 ° C. By performing the composite spinning in this manner, an optical fiber having a core-sheath structure with a diameter of 750 μm was manufactured for 2 days. Subsequently, the gear type metering pump 2 was stopped to produce an optical fiber having a diameter of 2000 μm,
The spinning nozzle 3 was replaced. At that time, the devolatilizing extruder 1 continued to operate, and all the extruded polymer was discharged from the polymer outlet 8. Then, the indicated value of the pressure sensor 11 becomes 1
Since the pressure rose to 50 kg / cm ² , the opening of the needle valve was loosened so that the pressure in the connecting pipe 6 became 50 kg / cm ² . The time required for replacing the spinning nozzle 3 was 3 hours. After the replacement, the operation of the gear type metering pump 2 was restarted, and an optical fiber having a yarn diameter of 2000 μ was spun. Three hours after the restart of spinning, an optical fiber having the same light transmission performance as before the replacement of the spinning nozzle 3 could be obtained.

(Example 2) An optical fiber was manufactured in the same manner as in Example 1, except that a needle valve having an automatic opening adjustment function using a spring was used as the pressure adjusting mechanism 7. Pressure sensor 11 even during spinning nozzle 3 replacement
Was stable at 50 kg / cm ² , and it was confirmed that no excessive load was applied to the devolatilizing extruder and the gear metering pump.

(Comparative Example 1)
After producing an optical fiber having a diameter of 2000 μm, the polymerization apparatus and the devolatilizing extruder 1 were stopped. The period required for stopping the polymerization apparatus and the devolatilizing extruder 1 was two days. Thereafter, the spinning nozzle 3 was replaced, and the operations of the polymerization apparatus and the devolatilizing extruder 1 were restarted. After restarting the operation, it took four days until an optical fiber having the same light transmission performance as before the replacement of the spinning nozzle 3 was obtained.

[0026]

According to the method of the present invention, it is possible to easily replace the shaping nozzle, and to prevent a decrease in productivity due to the replacement of the shaping nozzle. Further, according to the apparatus of the present invention, after exchanging the shaping nozzle, it is possible to produce a shaped body having the same properties as before the exchanging of the shaping nozzle without mixing of degraded substances generated at the time of exchanging the shaping nozzle. It is possible to shorten the time until

[Brief description of the drawings]

FIG. 1 is a schematic view of a shaping apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 devolatilizing extruder 2 gear-type metering pump 3 spinning nozzle 4 gear-type metering pump 5 extruder 6 communication pipe 7 pressure adjustment mechanism 8 polymer outlet 9 branch point 10 branch path 11 pressure sensor

Continued on the front page F term (reference) 2H050 AA15 AB43X AB43Y AB44X AB44Y AB47Y AB48Y AB50X AC03 4F207 AA21 AH77 KL54 4L045 AA05 BA01 BA18 BA60 CA16 CA36 CB19

Claims (3)

[Claims] 1. An extruder for exchanging a shaping nozzle of a molten resin shaping apparatus having an extruder, a shaping nozzle, a resin discharging means, and a resin flow path from the extruder to the shaping nozzle and the resin discharging means. A method of exchanging a shaping nozzle, wherein the shaping nozzle is replaced while discharging all of the resin extruded from the extruder from the resin discharging means while the machine is in operation. 2. A resin flow path includes a communication pipe communicating between an extrusion port of an extruder and a resin discharge means, and a plurality of branch paths disposed in the middle of the communication pipe and communicating with a plurality of shaping nozzles. The method for exchanging a shaping nozzle according to claim 1, wherein the shaping device is used. 3. An apparatus for forming a molten resin, comprising: an extruder, a resin discharging means, a plurality of forming nozzles, and a resin flow path from the extruder to each of the forming nozzles and the resin discharging means. A molten resin in which a resin flow path is constituted by a connecting pipe communicating between an extrusion port of an extruder and a resin discharging means, and a plurality of branch paths arranged in the middle of the connecting pipe and each communicating with a plurality of shaping nozzles. Shaping equipment.