Melting extrusion device and extrusion method

Abstract

To provide a melting extrusion device enabling stable melting extrusion of a thermoplastic resin to achieve linkage control of an amount of bite of a thermoplastic resin T to a screw 3 that shows fine and sudden changes and a supply amount of a material feeder 12 by paying an attention to the linkage control of a melting extrusion device 1 and a material feeder 12.SOLUTION: In a melting extrusion device for controlling a rotation number of a screw 3 based on a resin pressure detected by a pressure gauge 10 provided in a die 5 of a melting extrusion device 1, a raw material charging hole 6 for supplying a thermoplastic resin T to the melting extrusion device 1 is provided with an image monitoring device 14 for continuously image-monitoring a deposition state of a thermoplastic resin T in a flight channel 9 directly under the raw material charging hole. In the melting extrusion device, an image determination device 15 for determining images obtained by the image monitoring device 14 is connected to a feeder motor 13 of a material feeder 12 for supplying the thermoplastic resin T, and the image determination device 15 is connected to a motor 11 of the screw 3.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for melt extrusion of synthetic fibers. [Background technology]

[0002] Conventionally, the configuration of a melt extrusion device (see FIG. 3) is such that a screw 3 is provided inside a heating zone cylinder 4 for heating and melting a thermoplastic resin T, a motor 11 for rotating the screw 3 is provided on the rear end side of the screw, and the rotation speed of the screw 3 is controlled so that the reading of a pressure gauge 10 provided on a die 5 at the tip of the heating zone cylinder 4 is kept constant. In addition, a raw material inlet 6 for thermoplastic resin T is provided at the rear end of the screw, and a hopper 8 is attached to the upper part of the raw material inlet 6 via a conduit 7. A temperature control barrel 2 is provided to actively control the temperature inside the raw material inlet 6. Thermoplastic resin T is stored in the hopper 8 from a flight groove 9 located directly below the raw material inlet of the screw 3, and when the thermoplastic material T runs out, it is replenished manually or with an air-blowing type supply device. Alternatively, instead of the hopper 8, a material feeder 12 capable of measuring a fixed amount of thermoplastic resin T per unit time is used, and a preset supply amount of thermoplastic resin T is supplied into the raw material inlet 6 before measuring.

[0003] However, generally, when the thermoplastic resin T is at a high temperature, the thermoplastic resin T itself begins to soften. It is well known that when the pressure of the thermoplastic resin T accumulated in the hopper is applied to the thermoplastic resin T, adjacent thermoplastic resins become entangled with each other. When a conventional melt extrusion device is used, the thermoplastic resin T is accumulated from the flight groove of the screw directly below the raw material inlet to the hopper, so that the thermoplastic resins are strongly pressed against each other in the flight groove due to the load of the thermoplastic resin T stacked on the upper part, and the thermoplastic resins T are easily entangled and formed into large lumps, and there are also cases where they do not enter the flight groove. Furthermore, the pressure contact force of the thermoplastic resin T in contact with the screw changes depending on the amount of accumulation of the thermoplastic resin T, and the amount of the thermoplastic resin T that bites into the screw changes, making the metering unstable. Therefore, in order to stabilize the metering, it is essential to stabilize this amount of bite.

[0004] On the other hand, a method of controlling the temperature inside the raw material inlet hole is known as a means for stabilizing the amount of thermoplastic resin that is bitten into the screw. This is to improve the surface friction of the thermoplastic resin by adjusting the temperature of the thermoplastic resin, and stabilize the amount of thermoplastic resin that is bitten into the screw. However, depending on the type of thermoplastic resin, it is necessary to increase the temperature inside the raw material inlet hole, and if the thermoplastic resin is stored in the raw material inlet hole, the thermoplastic resin may become entangled and cannot be metered even if the temperature inside the raw material inlet hole is lower than the melting temperature.

[0005] In order to solve this problem, a method is sometimes used to supply a constant amount of thermoplastic resin T using a material feeder, but in known extrusion devices, the screw rotation speed is controlled by the pressure measured by a pressure gauge installed in the die, and the amount of thermoplastic resin T that the screw bites into changes successively. For this reason, when extrusion is performed for a long period of time, at some point the amount of thermoplastic resin T supplied from the material feeder exceeds the amount of thermoplastic resin T that the screw bites into, increasing the amount of thermoplastic resin T that remains, and adjacent pieces of thermoplastic resin T become entangled with each other and do not enter the flight grooves, At some time, the amount of thermoplastic resin T fed from the material feeder may be insufficient, making it impossible to obtain the desired extrusion capacity, resulting in poor extrusion.

[0006] In order to solve the above problems, Patent Document 1 proposes a method in which a monitor is provided at the molding material inlet section of an injection device, the accumulation state of molding material supplied from a material feeder is displayed as an image, and the accumulation state is determined based on the proportion of the screw surface in the image, and the material feeder is controlled to adjust the amount of molding material supplied. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2001-47214 A Summary of the Invention [Problem to be solved by the invention]

[0008] However, while the proposal described in Patent Document 1 is expected to be effective in injection molding applications where metal materials have a high softening temperature and stable supply over a short period of time are required, in extrusion molding applications of thermoplastic resins, which have a low softening temperature, where the amount of material that is bitten into the screw fluctuates successively, and where stable continuous supply over a long period of time is required, it is difficult to control the amount of thermoplastic resin that is bitten into the screw, which fluctuates finely and suddenly, and the amount of material supplied by the material feeder in conjunction with each other just by controlling the material feeder and image analysis in conjunction with each other, and as mentioned above, there are cases where the thermoplastic resin T becomes entangled and does not enter the flight groove, or there is a shortage of thermoplastic resin, making it unsuitable for achieving the desired extrusion capacity.

[0009] The present invention has been made in consideration of the above-mentioned shortcomings of the conventional technology, and provides a melt extrusion device that enables stable melt extrusion of thermoplastic resin T by controlling the amount of thermoplastic resin that is bitten into the screw, which fluctuates minutely and unexpectedly, in conjunction with the supply amount of the material feeder. [Means for solving the problem]

[0010] The present invention is configured as follows.

[0011] In a melt extrusion apparatus in which the rotation speed of a screw is controlled based on a resin pressure detected by a pressure gauge provided on a die of the melt extrusion apparatus, A raw material inlet 6 for supplying the thermoplastic resin T to the melt extrusion device 1 is provided with an image monitoring device 14 for constantly monitoring the deposition state of the thermoplastic resin T in the flight groove 9 immediately below the raw material inlet, An image determination device 15 for determining the image obtained by the image monitoring device 14 is connected to a feeder motor 13 of a material feeder 12 for supplying thermoplastic resin T, The image determination device 15 is connected to the motor 11 of the screw 3 in the melt extrusion apparatus.

[0012] This is a melt extrusion method in which, when melt extruding thermoplastic resin T using the melt extrusion device, an image judgment device 15 adjusts the amount of thermoplastic resin T supplied by the feeder motor 13 of the material feeder 12 based on the rotation speed of the motor 11 of the screw 3 of the melt extrusion device and the accumulation state of the thermoplastic resin T obtained by the image monitoring device 14, so as to keep the accumulation state of the thermoplastic resin T constant in the flight groove 9 directly below the raw material inlet hole. Effect of the Invention

[0013] According to the present invention, in a melt extrusion device in which the screw rotation speed is controlled by the pressure at the tip of the extruder, it is possible to extremely precisely control the amount of thermoplastic resin T deposited on the flight groove of the screw directly below the raw material inlet, thereby enabling stable extrusion without entanglement of the thermoplastic resin T or poor extrusion due to a lack of thermoplastic resin. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram showing a melt extrusion device according to the present invention. [Diagram 2] 11 is a corresponding state diagram for correcting and controlling the supply amount of material from a material feeder based on the deposition state of thermoplastic resin and the screw rotation speed. [Diagram 3] FIG. 1 is a schematic diagram showing a conventional melt extrusion device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The thermoplastic resin T used in the present invention is not particularly limited as long as it is a melt-spinnable thermoplastic resin. For example, polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polylactic acid, and polyethylene naphthalate, and polyamides such as nylon 6 and nylon 66 can be used.

[0016] In the present invention, the temperature of the heating zone cylinder 4 of the extruder for heating the resin raw material may be set to a temperature equal to or higher than the melting point of the resin raw material, and further, it is preferable to heat the heating zone cylinder 4 to a temperature equal to or higher than (Tm+10)° C., where Tm is the melting point of the resin raw material, to melt the resin raw material. For example, in the case of polyethylene terephthalate (melting point 260° C.), the temperature may be set to 270° C. or higher.

[0017] An example of an embodiment of the present invention will be described in detail with reference to the drawings. In the present invention, an extruder-type extruder equipped with a single screw is preferably used in a melt extrusion device that controls the rotation speed of the screw 3 based on the resin pressure detected by a pressure gauge 10 provided on the die 5 of the melt extrusion device 1. Examples of the type of single screw of the extruder-type extruder applied in the present invention include a screw having a single spiral shape and a screw provided with multiple spirals in the screw compression section, etc., but the present invention is not limited to these at all.

[0018] FIG. 1 is a schematic side view illustrating an extruder-type melt extrusion device equipped with a single screw used in the present invention, in which a heating zone cylinder 4 of the melt extrusion device 1 and a temperature control barrel 2 are provided with a rotatable screw 3 inside.

[0019] The effect of the present invention is remarkable when the screw diameter D is 65φ or less, but is not limited to this.

[0020] A pressure gauge 10 capable of detecting the pressure of the molten resin in the die 5 is provided at the tip of the heating zone cylinder 4, and the rotation speed of the screw 3 is increased or decreased so as to keep the pressure of the molten thermoplastic resin T detected by the pressure gauge 10 constant.

[0021] The temperature-controlled barrel 2 is structured to allow the introduction of a heat medium heated by a temperature control device in order to keep the temperature inside the barrel constant where it comes into contact with the thermoplastic resin T. The heat medium is preferably temperature-controlled oil, heated steam, heated air, etc., but is not limited to these in the present invention as long as it can be heated to the desired temperature. The actual temperature inside the temperature-controlled barrel 2 is preferably in the range of 40 to 180°C.

[0022] Furthermore, a raw material input hole 6 for thermoplastic resin T is provided on the upstream side of the temperature control barrel 2, and a variable-amount material feeder 12 is attached to the upper part of this raw material input hole, and the material feeder 12 can control the input amount of thermoplastic resin T by the rotation speed of a feed motor 13. Note that the material feeder 12 is not particularly limited as long as it can quantitatively input thermoplastic resin T to the raw material input hole, and various supply methods such as a screw feeder or a wooden box feeder can be used, for example.

[0023] Additionally, a hopper 8, which is a material storage section, is provided upstream of the material feeder 12 and stores thermoplastic resin T. The method of supplying material to the hopper 8 is not particularly limited, and examples include a method of blowing the thermoplastic resin T with a hose or the like, or a method in which an operator directly adds the material.

[0024] An image monitoring device 14 is provided for constantly monitoring the deposition state of the thermoplastic resin T in the flight groove 9 of the screw 3 directly below the raw material inlet 6, and an image judgment device 15 is provided for judging the image obtained by the image monitoring device 14, and is connected to the feed motor 13 of the material feeder 12.

[0025] It is preferable to use a floodlight 16 to project light onto the flight groove 9 directly below the raw material inlet, and it is particularly preferable that the illuminance of the light projecting part is 150 lx or more. When the illuminance is increased by the floodlight 16, the image obtained by the image monitor 14 is subjected to a binarization process, which is preferable because this improves the image judgment accuracy. It is also preferable that the floodlight 16 is located in the conduit 7 between the raw material inlet 6 and the material feeder 12, since this eliminates interference between the floodlight 16 and the supplied thermoplastic resin T.

[0026] In addition, the height of the flight groove 9 directly below the raw material input hole is preferably equal to or greater than the maximum thickness of the thermoplastic resin T, and the size and shape of the thermoplastic resin T are not particularly limited as long as the effects of the present invention are not impaired, specifically, as long as there is no extrusion failure due to poor supply stability of the thermoplastic resin T. The shape may be, for example, a sphere, an ellipsoid, a cube, a rectangular parallelepiped, a cylindrical body, an elliptical cylinder, or a flattened one of these, a granular shape, or a powder. In addition, recovered raw material chips or powdered recovered flakes made by pulverization, i.e., recovered raw materials, can be used as they are or mixed.

[0027] FIG. 2 shows the pile-up state of the raw material, the fluctuation state of the screw rotation speed which changes sequentially depending on the pressure value detected by the pressure gauge 10 inside the die 5 installed at the tip of the screw, and the supply amount correction value of the material feeder linked to the pile-up state of the raw material.

[0028] In order to automatically control the supply amount of the thermoplastic resin T, an image monitoring device 14, an image judgment device 15, a motor 11 of the screw 3, and a feeder motor 13 of the material feeder 12 are connected as shown in Fig. 1. That is, a signal from the image monitoring device 14 is input to the image judgment device 15, and the image is compared with a reference image of the piled-up state previously input to the image judgment device 15. Based on the increase or decrease in the screw rotation speed, which changes successively according to the pressure value detected by the pressure gauge 10 inside the die 5 provided at the tip of the screw, the required supply amount of the raw material from the material feeder 12 is predicted and corrected, and then the supply amount of the raw material from the material feeder 12 is controlled, thereby optimizing the piled-up state of the thermoplastic resin T.

[0029] 2, when the pile state of the raw material is good, the screw rotation speed does not change and the supply amount of the material feeder 12 is maintained because the pile state of the raw material is the same as the image input in advance to the image judgment device 15. Also, when the screw rotation speed is increasing, the discharge amount of the thermoplastic resin T increases, so the supply amount of the material feeder 12 is slightly increased. When the screw rotation speed is decreasing, the discharge amount of the thermoplastic resin T decreases, so the supply amount is slightly decreased.

[0030] Furthermore, when the piled-up state of the raw material is large, the piled-up state of the raw material is large compared to the image previously inputted to the image judgment device 15, so if the screw rotation speed does not change, the supply amount of the material feeder 12 is slightly reduced. When the screw rotation speed is increasing, the discharge amount of the thermoplastic resin T increases, so the supply amount of the material feeder 12 is maintained. When the screw rotation speed is decreasing, the discharge amount of the thermoplastic resin T decreases, so the supply amount of the material feeder 12 is reduced.

[0031] When the piled-up state of the raw material is small, the piled-up state of the material is small compared to the image previously inputted to the image judgment device 15, so if the screw rotation speed does not change, the supply amount of the material feeder 12 is slightly increased. When the screw rotation speed is increasing, the discharge amount of the thermoplastic resin T increases, so the supply amount of the material feeder 12 is increased. When the screw rotation speed is decreasing, the discharge amount of the thermoplastic resin T decreases, so the supply amount of the material feeder 12 is maintained.

[0032] As described above, it is essential to control the supply amount of the material feeder 12 in conjunction with the deposition state of the thermoplastic resin T and the screw rotation speed. EXAMPLES

[0033] The present invention will be described in detail below with reference to examples, but is not limited thereto. In this example, polyethylene terephthalate (melting point 260°C) was used as the thermoplastic resin T, and was melt-extruded by a melt extruder device as shown in Fig. 1. The temperature of the heating barrel cylinder 4 was set to 300°C, and the pressure value detected by the pressure gauge 10 inside the die 5 provided at the tip of a screw having a certain hole diameter was 80 [kgf / cm 2 The screw rotation speed was controlled so that the extrusion was carried out. The respective property values ​​of the examples and comparative examples in the extrusion were evaluated by the following methods.

[0034] (1) Frequency of discharge failure Polymer extrusion was carried out for 10 hours, and the pressure value detected by the pressure gauge 10 inside the die 5 was 10 [kgf / cm 2 The percentage of time that the response time was less than RT [%] was evaluated.

[0035] (2) Pressure fluctuation During the extrusion described in (1) above, the pressure (fluctuation) values ​​detected by the pressure gauge 10 were collected on a chart, and the percentage RP [%] of the fluctuation amount relative to the target pressure setting value was evaluated on the following three-level scale. ○: Excellent (RP is less than 10%) △: Normal (RP is less than 10-20%) ×: Inferior (RP is 20% or more).

[0036] (3) Raw material pile condition During the extrusion described in (1) above, the percentage RS [%] of the variation in the surface area of ​​the raw material actually measured by the image monitoring device 14 relative to the target surface area of ​​the raw material on the screw surface was evaluated on a three-level scale as shown below. ○: Excellent (RS is less than 10%) △: Normal (RS is less than 10-20%) ×: Inferior (RS is 20% or more).

[0037] (4) Overall evaluation Taking into consideration the frequency of discharge failures, pressure fluctuations, and the state of material accumulation, a comprehensive evaluation was conducted using the three stages shown below. The evaluation was judged to be acceptable (adoptable) with ○ and △. ○: Excellent (possible to adopt) △: Normal (adoptable) ×: Inferior (unacceptable) Examples 1 to 4 Using an extruder with a screw diameter Dφ25 mm, a polyethylene terephthalate resin raw material was supplied to the raw material inlet of the extruder by a material feeder 12, and the supply amount was linked to the screw rotation speed and the material feeder supply amount. Also, an image monitor 14 that constantly monitors the accumulation state of the raw material on the flight groove 9 of the screw 3 and an image judgment device 15 that judges the image obtained by the image monitor were used. The target set value of the raw material surface area occupying the screw surface was set to 20%, and the actual measured temperature inside the temperature control barrel 2 was 40 to 180 ° C., and the results were evaluated in a state where the supply section temperature control device was not used (actual temperature inside the temperature control barrel 2 was 220 ° C.). Table 1 shows the results. In addition, when the floodlight 16 was not installed and the test was performed with indoor dimming, the illuminance at the image monitoring position on the flight groove 9 of the screw was 50 lx.

[0038] [Table 1]

[0039] Examples 5 to 7 A floodlight 16 was provided in the conduit 7 between the raw material inlet 6 and the material feeder 12 so that the image monitoring position on the flight groove 9 of the screw could be illuminated, and the illuminance was set to 150 lx. The evaluation was performed in the same manner as in Examples 1 to 3, but the results are shown in Table 2.

[0040] [Table 2]

[0041] Examples 8 to 10 The results of evaluation performed in the same manner as in Examples 5 to 7, except that the screw diameter Dφ was set to 40 mm, are shown in Table 3.

[0042] [Table 3]

[0043] Examples 11 to 13 The results of evaluation performed in the same manner as in Examples 5 to 7, except that the screw diameter Dφ was 15 mm, are shown in Table 4.

[0044] [Table 4]

[0045] Comparative Examples 1 to 13 Table 5 shows the results of evaluation carried out in the same manner as in Examples 1 to 13, except that the method of controlling the raw material supply amount was such that the screw rotation speed and the material feeder supply amount were not linked.

[0046] [Table 5] [Explanation of symbols]

[0047] 1: Melt extrusion equipment 2: Temperature controlled barrel 3: Screw 4: Heating cylinder 5: Die 6: Raw material input hole 7: Conduit 8: Hopper 9: Flight groove directly below the raw material inlet 10: Pressure gauge 11:Motor 12: Material feeder 13: Feed motor 14: Image monitoring device 15: Image judgment device 16: Floodlight

Claims

1. In a melt extrusion apparatus, the rotation speed of a screw is controlled based on a resin pressure detected by a pressure gauge provided on a die of the melt extrusion apparatus, An image monitoring device 14 is provided at a raw material inlet 6 for supplying a thermoplastic resin T to the melt extrusion device 1, and the image monitoring device 14 constantly monitors an accumulation state of the thermoplastic resin T in a flight groove 9 immediately below the raw material inlet. An image determination device 15 for determining the image obtained by the image monitoring device 14 is connected to a feeder motor 13 of a material feeder 12 for supplying thermoplastic resin T. The image determination device 15 is connected to the motor 11 of the screw 3 in the melt extrusion apparatus.

2. 2. The melt extrusion apparatus according to claim 1, further comprising a temperature control device having a temperature control barrel for controlling the temperature inside the raw material inlet.

3. 3. The melt extrusion apparatus according to claim 1, further comprising a light projector disposed in the conduit between the raw material inlet and the material feeder.

4. A melt extrusion method in which, when melt extruding a thermoplastic resin T using the melt extrusion apparatus of claim 1, an image judgment device 15 adjusts the supply amount of thermoplastic resin T supplied by the feeder motor 13 of the material feeder 12 based on the rotation speed of the motor 11 of the screw 3 of the melt extrusion apparatus and the accumulation state of the thermoplastic resin T obtained by the image monitoring device 14 so as to keep the accumulation state of the thermoplastic resin T constant in the flight groove 9 immediately below the raw material inlet hole.

Images