阅读说明：本技术 挤出机 (Extruding machine ) 是由 李圭一 丁柄准 崔祐铣 崔荣现 廉应燮 于 2020-08-13 设计创作，主要内容包括：本发明提供一种挤出机,其被配置为挤出含有水分的固体原料,该挤出机包括：料筒,在纵向方向上具有中空管形状,其中,原料送入其中的料斗耦接到料筒的一侧,排出口设置在料筒的另一侧,脱水的原料通过排出口排出,并且狭槽部设置在排出口与料斗之间的特定部分中,料筒的内部与外部通过狭槽部彼此连通；棒状螺杆,在其外周面上设置有螺纹,使得螺杆被安装在料筒内,以在沿一个方向轴向旋转的同时将送入料斗中的原料输送到排出口；以及加热器部,安装在料筒上以加热原料。通过料斗引入料筒中的原料在通过螺杆在料筒内输送的同时,被加热器部逐渐加热。形成在螺杆上的捏合区,在捏合区中压缩通过螺纹输送的原料。由于原料在料筒内熔化,使得原料的至少一部分相变为液态,控制加热器部的加热温度和螺杆的轴向旋转速度,从而在捏合区中由相变的原料形成遮蔽料筒的内部横截面的密封膜。(The present invention provides an extruder configured to extrude a solid feedstock containing moisture, the extruder comprising: a barrel having a hollow tube shape in a longitudinal direction, wherein a hopper into which raw material is fed is coupled to one side of the barrel, a discharge port is provided at the other side of the barrel, dehydrated raw material is discharged through the discharge port, and a slit part through which the inside and the outside of the barrel communicate with each other is provided in a specific portion between the discharge port and the hopper; a rod-shaped screw provided with a thread on an outer peripheral surface thereof such that the screw is installed in the barrel to convey the raw material fed into the hopper to the discharge port while axially rotating in one direction; and a heater part installed on the cartridge to heat the raw material. The raw material introduced into the barrel through the hopper is gradually heated by the heater portion while being conveyed inside the barrel by the screw. A kneading zone formed on the screw in which the raw material conveyed by the screw is compressed. At least a part of the raw material is phase-changed to a liquid state as the raw material is melted in the barrel, and the heating temperature of the heater section and the axial rotation speed of the screw are controlled, thereby forming a sealing film that shields the inner cross section of the barrel from the phase-changed raw material in the kneading zone.)

1. An extruder configured to extrude a solid feedstock containing moisture, the extruder comprising:

a barrel having a hollow tube shape in a longitudinal direction, wherein a hopper is coupled to one side of the barrel, raw material is fed into the hopper, a discharge port is provided at the other side of the barrel, dehydrated raw material is discharged through the discharge port, and a slit part through which the inside and the outside of the barrel communicate with each other is provided in a specific portion between the discharge port and the hopper;

a rod-like screw provided with a thread on an outer peripheral surface thereof such that the screw is installed within the barrel to convey the raw material fed into the hopper to the discharge port while axially rotating in one direction; and

a heater part mounted on the cartridge to heat the raw material,

wherein the raw material introduced into the barrel through the hopper is gradually heated by the heater section while being conveyed inside the barrel by the screw,

a kneading zone formed on the screw in which the raw material conveyed by the flight is compressed, and

at least a part of the raw material is phase-changed to a liquid state as the raw material is melted in the barrel, and the heating temperature of the heater section and the axial rotation speed of the screw are controlled so that a sealing film that shields the inner cross section of the barrel is formed from the phase-changed raw material in the kneading zone.

2. The extruder of claim 1, wherein the kneading zone is disposed between the throat section and the hopper.

3. The extruder of claim 1, wherein a plurality of slots are provided spaced apart from one another in the slot portion.

4. The extruder of claim 3, wherein the plurality of slots are spaced from each other a predetermined distance along a circumference of the barrel.

5. Extruder according to claim 4, wherein the width of at least one of the slots is greater than the width of each of the other slots.

6. Extruder according to claim 2, wherein the distance between the kneading zone and the throat section is less than three times the diameter of the barrel.

7. Extruder according to claim 2, wherein the distance between the kneading zone and the hopper is more than five times the diameter of the barrel.

8. The extruder of claim 2, wherein the screw comprises:

a first forward region in which the screw thread is arranged to convey the feedstock fed from the hopper towards the discharge outlet on axial rotation;

the kneading zone in which the screw is provided to compress the raw material conveyed from the first forward zone upon axial rotation; and

a second forward zone in which the screw is arranged to convey the feedstock passing through the kneading zone toward the discharge port upon axial rotation.

9. The extruder according to claim 8, wherein the kneading zone comprises a neutral zone in which the screw thread is provided on the outer peripheral surface of the rod to urge the raw material to rotate in situ.

10. The extruder according to claim 8, wherein the kneading zone comprises a reverse zone in which the screw is provided on the outer peripheral surface of the rod-like shape to convey the raw material in a direction opposite to a direction in which the raw material is conveyed by the screw provided in the first forward zone.

11. The extruder according to claim 8, wherein the kneading zone is constituted by connecting the neutral zone in which the screw is provided on the outer peripheral surface of the rod-like shape to urge the raw material to rotate in place with the reverse zone in which the screw is provided on the outer peripheral surface of the rod-like shape to convey the raw material in a direction opposite to the direction in which the raw material is conveyed by the screw provided in the first forward zone,

wherein the neutral region is connected to the first forward region and the reverse region is connected to the second forward region.

12. The extruder according to claim 8, wherein the screw further comprises a first sub-kneading block in which the screw is provided to re-compress the raw material conveyed from the second forward direction block while rotating axially.

13. The extruder according to claim 12, wherein the screw further comprises a third forward zone in which the flight is provided to convey the raw material passing through the first sub-kneading zone toward the discharge port while rotating axially, and

a sub-slot portion configured to discharge gas separated from the raw material, the sub-slot portion being disposed within a range in which the third forward region is formed in the cartridge.

14. The extruder according to claim 13, wherein the screw further comprises a second sub-kneading block in which the screw is arranged to re-compress the raw material conveyed from the third forward direction block while rotating axially.

15. The extruder according to claim 14, wherein the screw further comprises a fourth forward zone in which the flight is provided to convey the raw material passing through the second sub-kneading zone toward the discharge port while rotating axially, and

a sub-exhaust portion configured to exhaust impurities contained in the raw material to the outside is provided in a range in the cartridge where the fourth forward region is formed.

16. The extruder according to any one of claims 1 to 15, further comprising a pulverizing device configured to pulverize the raw material discharged from the discharge opening of the barrel.

Technical Field

The present invention relates to an extruder for extruding a solid raw material containing moisture, and more particularly, to an extruder having a region in which backflow of moisture discharged from the raw material is prevented (the raw material in a barrel forms a sealing film in the region).

Background

In a process for producing a thermoplastic resin prepared by emulsion polymerization, the produced thermoplastic resin is usually obtained in a latex state together with a dispersion medium. Therefore, the raw material contains a large amount of moisture.

Accordingly, the process of manufacturing the thermoplastic resin includes a dehydration and drying process for removing moisture.

As a known drying process, a method of evaporating moisture by applying thermal energy to a dehydrated raw material while the raw material is moving or stationary is generally employed.

Subsequently, the dried raw material was heated and pressurized using an extruder shown in fig. 1 as necessary, thereby obtaining a granulated dried raw material.

Referring to fig. 1, there is shown an internal configuration of an extruder according to the prior art, which is configured such that a hopper 2 is installed at one side of a tubular barrel 1, raw material is fed through the hopper 2, and the raw material is discharged to a discharge port (left side outlet in the figure) through an internal screw 5.

The raw material injected through the hopper 2 is heated by a heater (not shown) installed inside or outside the barrel and is extruded by the screw 5. Therefore, the water vapor generated from the moisture remaining in the dried raw material is separated while the dried raw material is moved by the screw 5. The separated water vapor is discharged to the outside through a gas discharge portion 6 provided away from the hopper 2.

However, in such a structure according to the prior art, when the raw material passes through the screw 5, the water vapor generated in the barrel 1 does not reach the exhaust portion 6 but flows back to the hopper 2. The backflow of water vapor has an adverse effect on smooth input of raw materials and deteriorates extrusion performance.

For this purpose, according to the prior art, a check plate 4 for minimizing the effect of backflow of water vapor and an introduction screw 3 for injecting the raw material into the barrel are additionally provided in the hopper 2.

Disclosure of Invention

Technical problem

Accordingly, an object of the present invention is to provide an extruder capable of directly extruding a dehydrated raw material without a drying process and preventing water vapor separated from the raw material from flowing back into a hopper, thereby improving extrusion efficiency.

Technical scheme

In order to achieve the above object, the present invention provides an extruder configured to extrude a solid raw material containing moisture, the extruder comprising: a barrel having a hollow tube shape in a longitudinal direction, wherein a hopper into which raw material is fed is coupled to one side of the barrel, a discharge port is provided at the other side of the barrel, dehydrated raw material is discharged through the discharge port, and a slit part through which the inside and the outside of the barrel communicate with each other is provided in a specific portion between the discharge port and the hopper; a rod-shaped screw provided with a thread on an outer peripheral surface thereof such that the screw is installed in the barrel to convey the raw material fed into the hopper to the discharge port while axially rotating in one direction; and a heater section installed on the barrel to heat the raw material, wherein the raw material introduced into the barrel through the hopper is gradually heated by the heater section while being conveyed inside the barrel by the screw, a kneading zone is formed on the screw, the raw material conveyed by the screw is compressed in the kneading zone, and at least a part of the raw material is phase-changed to a liquid state as the raw material is melted inside the barrel, so that a heating temperature of the heater section and an axial rotation speed of the screw are controlled to form a sealing film shielding an inner cross section of the barrel from the phase-changed raw material (in a liquid state or in a solid-liquid mixed state) in the kneading zone.

The kneading zone is disposed between the slot section and the hopper.

The plurality of slots are disposed to be spaced apart from each other in the slot portion. In the present invention, the plurality of slots may be spaced apart from each other by a predetermined distance along the circumference of the cartridge. The width of at least one slot may be greater than the width of each of the other slots.

The distance between the kneading zone and the slot section may be less than three times the diameter of the barrel, and the distance between the kneading zone and the hopper may be more than five times the diameter of the barrel.

The screw rod includes: a first forward region in which the screw is arranged to convey material input from the hopper towards the discharge outlet on axial rotation; a kneading zone in which the screw is arranged to compress the material being fed from the first forward zone upon axial rotation; and a second forward zone in which the screw is arranged to convey the material passing through the kneading zone toward the discharge port upon axial rotation.

The kneading zone may comprise: a neutral zone in which a thread is provided on an outer circumferential surface of the rod to urge the raw material to rotate in situ; or a reverse zone in which a screw is provided on the outer circumferential surface of the rod-like shape to convey the raw material in a direction opposite to a direction in which the raw material is conveyed by the screw provided in the first forward zone. Further, the kneading zone may be constituted by connecting a neutral zone in which a screw is provided on the outer peripheral surface of the rod-like shape to urge the raw material to rotate in place, and a reverse zone in which a screw is provided on the outer peripheral surface of the rod-like shape to convey the raw material in a direction opposite to a direction in which the raw material is conveyed by the screw provided in the first forward zone, wherein the neutral zone is connected to the first forward zone and the reverse zone is connected to the second forward zone.

The screw further comprises a first sub-kneading block in which the screw is arranged to re-compress the material fed from the second forward block while rotating axially.

In addition, the screw may further include a third forward zone in which the screw is provided to convey the raw material passing through the first sub-kneading zone toward the discharge port while axially rotating, and a sub-slot portion configured to discharge gas separated from the raw material may be provided within a range of the barrel in which the third forward zone is formed.

Further, the screw may further comprise a second sub-kneading block in which the screw is arranged to compress the raw material fed from the third forward direction block again upon the axial rotation.

In addition, the screw further includes a fourth forward zone in which the screw is provided to convey the raw material passing through the second sub-kneading zone toward the discharge port while axially rotating, and a sub-discharge portion configured to discharge impurities contained in the raw material to the outside is provided within a range in which the fourth forward zone is formed in the barrel.

The extruder may further include a pulverizing device configured to pulverize the raw material discharged from the discharge port of the barrel.

Advantageous effects

In the extruder having the above-described structure according to the present invention, the sealing film is formed in the kneading zone while the raw material is extruded in the barrel, and therefore, the backflow of water vapor to the hopper can be prevented or minimized.

The kneading zone may include one of a neutral zone or a reverse zone or a combination thereof, and thus may be selectively employed depending on the state or properties of the raw materials.

In addition, the screw according to the present invention may further include a first sub-kneading block and a second sub-kneading block, and thus, a sealing film may be additionally formed, thereby more effectively preventing backflow of water vapor.

Drawings

Fig. 1 is a perspective view showing an internal configuration of an extruder according to the related art.

Fig. 2 is a perspective view showing an internal configuration of an extruder according to the present invention.

Fig. 3 is an enlarged view of a portion provided with a kneading zone in fig. 2.

Fig. 4 is a view showing an example (A, B, C) of the screw thread of the kneading block suitable for use in the present invention.

FIG. 5 is a view showing a cross section before and after forming a sealing film in the kneading zone.

Fig. 6 is a view showing a distance with respect to the diameter D of the barrel in the extruder of the present invention.

Detailed Description

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily carry out the present invention. This invention may, however, be embodied in several different forms and is not limited to the embodiments set forth herein.

Portions that are not relevant to the description will be omitted in order to clearly describe the present invention, and the same reference numerals will be given to the same or similar elements throughout the description.

In addition, the terms or words used in the present specification and claims should not be construed restrictively as a general meaning or a dictionary-based meaning, but should be construed as a meaning and concept conforming to the scope of the present invention based on the principle that an inventor can appropriately define the concept of the term to describe and explain his or her invention in the best way.

The present invention relates to an extruder for extruding a solid raw material containing moisture, and hereinafter, the extruder according to the present invention will be described in more detail with reference to the accompanying drawings.

Referring to fig. 2, which shows an internal configuration of an extruder according to the present invention including a barrel 10, a screw 30 installed in the barrel 10, a slit part 40A through which water vapor in the barrel 10 is discharged to the outside, and a heater part 60 for heating the barrel 10. Further, a sealing film is formed of a molten resin in the cartridge 10.

The cartridge 10 has a hollow tubular shape in the longitudinal direction. A hopper 20 (into which the raw material is fed through the hopper 20) is coupled to one side of the barrel 10, and a discharge port 11 for discharging the dehydrated raw material is provided at the other side of the barrel 10.

The cartridge 10 is preferably made of metal having excellent chemical resistance or is manufactured such that the inner surface thereof is coated with a protective material to prevent corrosion due to volatile substances and water vapor discharged from the raw materials. The cartridge 10 is manufactured to have a rigidity sufficient to withstand heat and pressure generated from the inside.

The screw 30 is rod-shaped and has a structure in which a thread M (31, 32, 33) is provided on the outer peripheral surface thereof. Further, the screw 20 conveys the raw material fed from the hopper 20 toward the discharge port 11 while being mounted in the barrel 10 and axially rotated in one direction.

At this time, a screw thread M having a spiral shape is provided on the outer circumferential surface of the screw 30 in the longitudinal direction. The region where the screw M is formed in the direction in which the raw material is moved toward the discharge port is divided into forward zones (F1 section, F2 section, F3 section, and F4 section). Further, the region in which the screw is formed to rotate only the raw material without moving the raw material, or to move the raw material in the reverse direction (i.e., to move the raw material from the discharge port of the barrel toward the hopper) is divided into the kneading block 30A, the first sub-kneading block 30B, and the second sub-kneading block 30C.

Referring to fig. 3 showing an enlarged view of a portion K1, the kneading block 30A of fig. 2 is provided in the kneading block 30A, and fig. 4 shows the shape of the screw adapted to the kneading block 30A, the screw provided in the kneading block 30A being configured to compress the raw material instead of conveying the raw material. (the upper part of FIG. 3 is a state in which the casing is coupled to the outside of the screw, and the lower part of FIG. 3 is a state in which the casing is removed. therefore, hereinafter, it will be described with reference to the following figures) the kneading zone 30A includes a neutral zone in which a neutral screw 32 is provided on the outer circumferential surface of the rod-like shape to introduce the raw material to rotate in place, and a reverse zone in which a screw 33 is provided on the outer circumferential surface of the rod-like shape to convey the raw material in the opposite direction. That is, the present invention provides the configurations in examples 1, 2 and 3 in which only the neutral zone is provided in the kneading zone, only the reverse zone is provided in the kneading zone, and the neutral zone and the reverse zone are combined, respectively.

As shown in fig. 4(C), the neutral threads 32 provided in the neutral zone may not have a form in which the threads are connected to each other in a spiral shape, but have a separately separated form (i.e., a form in which the ring-shaped threads are connected to each other with a space therebetween). When the material reaches the neutral thread 32 of the form described above, the force applied to the material produces rotation in situ rather than conveying the material.

In addition, as shown in fig. 3 and 4(B), the reverse threads 33 defined in the reverse zone are disposed in a direction opposite to that of the threads disposed in the forward zone. The counter-thread 33, which has the form described above, generates a force that transports the material in the opposite direction when it arrives.

Alternatively, as shown in fig. 4(a), the neutral region may be configured in combination with the reverse region.

When the raw material reaches the kneading zone 30A provided with the neutral zone and/or the reverse zone, the raw material is gathered together with the raw material continuously supplied from the forward zone on the rear side to be extruded.

Here, in the present invention, the screw 30 may have an F1 section, an F2 section, an F3 section, and an F4 section in which a plurality of forward kneading blocks are provided, and a K1 section and a K2 section in which a plurality of kneading blocks are provided. That is, as shown in fig. 2, there is provided a structure in which a first forward direction zone (portion F1), a kneading zone (portion K1), a second forward direction zone (portion F2), a first sub-kneading zone (portion K2), a third forward direction zone (portion F3), a second sub-kneading zone (portion K3), and a fourth forward direction zone (portion F4) are arranged in this order from the hopper 20.

A forward flight 31 is provided in the first forward zone to convey the raw material fed from the hopper 20 toward the discharge port 11 upon axial rotation, and a neutral flight 32 or a reverse flight 33 is provided in the kneading zone 30A to compress the raw material conveyed from the first forward zone upon axial rotation of the screw 30. Further, the neutral screw 32 or the reverse screw 33 provided in the first sub-kneading block 30B and the second sub-kneading block 30C is similar to the kneading block 30A, and the forward screw provided in the second forward block, the third forward block and the fourth forward block is similar to the first forward block. In addition, a slot 40A is provided in the barrel 10 so that the steam (and separated gases, etc.) is discharged after the raw material passes from the hopper 20 through the kneading zone 30A. A plurality of slots are provided in the slot portion 40A to be spaced apart from each other. Preferably, the slot has an elongated hole shape and is arranged in a direction parallel to the longitudinal direction of the cartridge 10.

At this time, the slots may be spaced apart from each other by a predetermined distance along the circumference of the cartridge 10. That is, in the case where the cartridge 10 has a cylindrical tubular shape, the slot portion 40A may be provided such that the slots are arranged in a ring-like form along the entire circumference of the cartridge 10. However, in order to adjust the discharge direction of the water vapor inside the cartridge 10, a slot may be provided only in a specific portion of the cartridge 10.

That is, in the case where the slit is also provided in the lower portion of the cartridge 10, not only water but also a part of the raw material may be discharged due to gravity, and thus, the slit may not be provided in the lower portion of the cartridge 10. Further, the width or area of the slots in a particular section may be greater than the width or area of other slots for the same reason. For example, the slots provided in the lower surface of the cartridge 10 may be formed narrow to prevent the raw material from falling, and the slots provided in the upper surface may be formed wide and large to facilitate the discharge of water vapor.

In addition, the slit portion 40A may be provided in a simple perforated form, but an openable and closable valve, a vent for discharging water vapor, and a safety vent that opens only at a certain pressure or higher may be additionally coupled to the slit portion 40A.

Further, a heater part 60 for generating heat is coupled to an outer surface of the cartridge 10 (or an inside thereof). The heater part 60 may be a device that converts electric energy into heat energy, or a device that receives a heat source from the outside to heat the cartridge.

A plurality of heater parts 60 are mounted on the entire cartridge 10, and the temperatures of the heater parts 60 can be individually controlled. Thus, the barrel 10 is configured so that each section (forward zone and kneading zone) can be temperature-controlled.

In the extruder having the above-described structure according to the present invention, when the raw material stored in the hopper 20 is supplied into the barrel 10, the raw material is conveyed by the screw 30 within the barrel 10 and heated (or cooled) to a target temperature by the heater part 60.

At this time, when the raw material passes through the first forward direction section and reaches the kneading section 30A, the raw material is extruded in a heated state by the raw material continuously supplied from the rear side and the rotational force of the screw 30.

Thus, the heated and pressurized raw materials are melted in the kneading zone 30A (or before reaching the kneading zone), and at least a part or almost all of the raw materials are phase-changed into a liquid state.

That is, while the raw material heated and pressurized in the kneading zone 30A is changed from a solid state to a highly viscous liquid state, the raw material is radially diffused by the centrifugal force generated in the kneading zone 30A.

Therefore, as shown in fig. 5 showing the cross section before and after the sealing film is formed in the kneading zone 30A, the solid raw material, water vapor separated from the raw material, and the like in the front portion (near the hopper) of the kneading zone 30A diffuse into the space between the screw 30 and the barrel 10. Further, with the continuous application of heat and pressure, most of the solid raw material at the rear portion (near the discharge port) of the kneading zone 30A is melted into a liquid state. At this time, a sealing film shielding the cross section of the cartridge 10 is formed from the melted raw material by centrifugal force.

At this time, the thickness and the formation position of the sealing film may vary depending on the rotation speed of the screw 30, the heating temperature of the heater section 60, and the arrangement of the flights provided in the kneading zone 30A. Further, in the cartridge 10, the sealing film is formed in a variable state rather than a fixed state.

That is, the sealing film is formed as a liquid film, and as the raw materials are continuously supplied, the raw materials first formed with the sealing film pass through the kneading zone 30A and then are discharged toward the second forward zone. Then, the subsequently supplied raw material becomes liquid and holds the sealing film while replenishing the previously discharged raw material.

The heating temperature of the heater section 60 and the axial rotation speed of the screw are controlled according to the state and amount of the raw material fed for continuously holding the sealing film.

The liquid raw material and the vapor of gaseous water vapor that have passed through the kneading block 30A are fed to the second forward direction block F2. At this time, the liquid raw material is continuously conveyed along the screw 30, but the gaseous water vapor (and the gas generated during the phase transition) is discharged to the outside through the slit portion 40A. At this time, the backflow of water vapor to the hopper 20 is prevented by the sealing film formed in the kneading zone 30A.

Further, the raw material reaching the first sub-kneading block 30B again forms a sealing film in the portion K2 inside the first sub-kneading block 30B, and is then conveyed to the discharge port 11 through the third forward direction block. The gas, excess water vapor, and the like contained in the raw material are discharged to the outside through the sub-slit portion 40B while being transported through the third forward direction zone. The structure of sub-slot portion 40B may be the same as or similar to the structure of slot portion 40A described above.

In addition, the raw material having passed through the first sub-kneading block 30B is fed to the third forward direction block F3, and then reaches the second sub-kneading block 30C. The raw material formed a sealing film in the portion K3 in the second sub-kneading block 30C and was then discharged to the discharge port 11 through the fourth forward direction block.

Impurities (residual monomers, etc.) contained in the raw material, gas generated during the phase transition, excessive water vapor, etc. are discharged to the outside through the sub-exhaust part 50 while being transported through the fourth forward zone. In order to finally discharge impurities (residual monomers, etc.) contained in the raw material, the sub-exhaust part 50 may be provided with a pipe shape having an opening area larger than the opening areas of the slit part 40A and the sub-slit part 40B.

Further, the raw material discharged to the discharge port 11 of the barrel 10 is cooled after water vapor, gas, and the like are separated therefrom, and then discharged in the form of a solid block.

The raw material discharged in the form of a solid block is cut into particles having a certain size by a pulverizing device 70 for pulverizing the dehydrated (dried) raw material.

In addition, in the extruder of the present invention, it is preferable to limit the distance between the parts to improve drying and dehydrating performance.

That is, as shown in fig. 6, which shows the respective distances with respect to the diameter D of the barrel in the extruder of the present invention (at this time, fig. 6 is not drawn to scale due to size limitation). Preferably, the distance from the hopper 20 to the kneading zone 30A is set to 5D to 10D based on the diameter D of the barrel 10.

Further, the distance between the kneading block 30A and the slit part 40A is preferably set to 3D or less, the distance between the slit part 40A and the first sub-kneading block 30B is preferably set to 3D or more, and each of the distance between the first sub-kneading block 30B and the sub-slit part 40B and the distance between the sub-air discharge part 50 and the second sub-kneading block 30C is preferably set to 3D or less.

However, these relative distances are not limited to the above ranges, and may be changed according to the length and axial rotational speed of the screw 30, the state of the raw material, the output of the heater section 60, and the like.

In the extruder having the above-described structure according to the present invention, the sealing film is formed in the kneading zone 30A while the raw material is dehydrated in the barrel 10, and therefore, the backflow of water vapor into the hopper 20 can be prevented or minimized.

The kneading zone 30A may include one of a neutral zone or a reverse zone or a combination thereof, and thus may be selectively employed depending on the state or properties of the raw materials.

Further, in the present invention, since the screw 30 may further include the first sub-kneading block 30B and the second sub-kneading block 30C, a sealing film may be additionally formed. Therefore, while preventing the backflow of water vapor as effectively as possible, water vapor can be discharged through the slit portion 40A and the sub-slit portion 40B as much as possible.

Further, in the extruder of the present invention, since moisture contained in the raw material is discharged through the slit portion 40A and the sub-slit portion 40B while being extruded, impurities (residual monomers, etc.) contained in the raw material can be discharged as much as possible through the sub-venting portion 50.

At this time, the extruder of the present invention may be an apparatus for extruding a thermoplastic resin. The thermoplastic resin may be a thermoplastic resin that can be pelletized by an extruder, and as a specific example, may be a diene-based graft copolymer. As a more specific example, the diene-based graft copolymer may be an acrylonitrile-based butadiene styrene (acrylonitrile butadiene styrene) graft copolymer.

The diene-based graft copolymer is generally produced by an emulsion polymerization method, and is obtained in a latex state in which colloidal particles of the completely polymerized diene-based graft copolymer are dispersed in water serving as a dispersion medium, that is, in a solid state containing moisture. Subsequently, the diene-based graft copolymer is obtained in the form of a dry powder by subjecting the diene-based graft copolymer, which has been obtained in a latex state, to aggregation, dehydration and drying steps. However, the diene-based graft copolymer obtained in the form of a dry powder has a problem in that a blocking phenomenon occurs due to aggregation and coagulation between the dry powders upon long-term storage.

However, the extruder of the present invention can effectively remove moisture from a solid raw material containing moisture while extruding. Therefore, in the case of extruding the diene-based graft copolymer by using the extruder of the present invention, the dehydrated diene-based graft copolymer can be directly extruded without drying the diene-based graft copolymer obtained in a latex state.

Further, the bulk density of the diene-based graft copolymer extruded by using the extruder of the present invention is higher than that of dry powder, and thus the occurrence of the blocking phenomenon upon long-term storage can be prevented.

As described above, the extruder of the present invention can more efficiently obtain the thermoplastic resin, the diene-based graft copolymer as a specific example, and the acrylonitrile-based butadiene styrene graft copolymer as a further specific example.

Although the present invention has been described by way of specific embodiments and drawings, the present invention is not limited thereto, and various changes and modifications may be made by those skilled in the art to which the present invention pertains within the scope of the technical idea of the present invention and the equivalent scope of the appended claims.

[ description of reference numerals ]

10: charging barrel

20: hopper

30: screw rod

40A: slot section

40B: sub-slot part

50: sub-exhaust part

60: a heater section.