JP6687271B1 - Foam resin extrusion equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust a supply pressure of a resin material and an injection pressure of a foaming gas. SOLUTION: A resin material supplied into a cylinder 3 is fed while rotating a screw 2 arranged in the cylinder 3 to inject a foaming gas and mix them, and an extrusion die 8 die outlet 8a. Through a porous thermoplastic synthetic resin. The screw shaft 2a of the screw 2 includes a foaming gas passage 6 and a gas injection passage 6c that communicates with the foaming gas passage 6 and opens on the surface of the screw shaft 2a. The opening of the gas injection path 6c increases the supply pressure of the resin material, and the foaming gas injection section S2 in which the gas injection path 6c opens is disposed downstream of the dullage section S1 that locally seals the inside of the cylinder 3. ing. [Selection diagram]

Description

  TECHNICAL FIELD The present invention relates to a foamed resin extrusion device capable of producing a foamed resin.

  In order to produce a foamed resin in an extruder, it is necessary to inject a foaming gas into the resin material. In the extruder, since the resin material in the cylinder is pressurized and sent by the screw, in order to inject the foaming gas, it is necessary to inject at a pressure higher than the supply pressure of the resin material in the cylinder. This is because if the injection pressure is lower than the supply pressure of the resin material, not only injection will not be possible, but also the resin material in the cylinder may flow into the injection passage of the foaming gas and block the injection port. Further, if the injection pressure is too high, there is a problem that the resin material flows into the resin material supply port and the die exit of the extrusion die as they are.

  Therefore, when injecting the foaming gas, it is necessary to adjust the relationship between the injection pressure and the supply pressure of the resin material that changes depending on the rotation speed of the screw and the molding temperature.

  By the way, it has been proposed to inject a foaming gas or a foaming agent into the cylinder through the inside of the screw shaft and from the shaft surface or the rear opening of the screw thread (for example, refer to Patent Document 1).

JP-A-5-228977

  Although the technique of Patent Document 1 makes it easy to control the injection pressure, it is not possible to simply inject the foaming gas into the resin material only by controlling the injection pressure. That is, when injecting the foaming gas, it is important to adjust the relationship between the injection pressure and the supply pressure of the resin material that changes depending on the rotation speed of the screw and the molding temperature.

  Therefore, the inventor devised a structure of a screw arranged in a cylinder, in addition to forming a foaming gas supply passage on a screw shaft when injecting a foaming gas into a resin material to produce a foamed resin. Therefore, if the cylinder has a plurality of sections (that is, a plurality of sections for controlling the supply pressure of the resin material) inside, the relationship between the supply pressure of the resin material and the injection pressure of the foaming gas is adjusted. The present invention was developed by finding that it can be easily achieved.

  An object of the present invention is to provide a foamed resin extruding device capable of easily adjusting the supply pressure of the resin material and the injection pressure of the foaming gas.

The present invention has a cylinder in which a screw, in which screw blades are spirally wound around a screw shaft, is arranged, and foams a resin material supplied into the cylinder while rotating the screw to feed the resin material. A foaming resin extruding device for injecting a working gas, mixing them, and extruding as a porous thermoplastic synthetic resin through a die outlet of an extrusion die, wherein a screw shaft of the screw has a foaming gas supply path extending in an axial direction. And a gas injection path having an upstream end communicating with the foaming gas supply path and a downstream end opening to the surface of the screw shaft, which locally increases the supply pressure of the resin material in the cylinder and seals the gas. The gas injection section is formed at a portion where a Darmage section exhibiting a function is formed, and the supply pressure of the resin material is released and decreases on the downstream side of the Darmige section. The downstream end of the road is located is open foaming gas injection section in which the foaming gas is injected, the dull image section, throttle member to increase the supply pressure of locally resin material on the screw shaft of the screw is provided The gas injection passage is formed so as to extend obliquely from the foaming gas supply passage toward the throttle member in the foaming gas injection section .

By doing so, for foaming, which is a portion where the supply pressure of the resin material is released and decreases on the downstream side of the dullage section that locally increases the supply pressure of the resin material and exerts the sealing function. In the gas injection section, the gas injection path is opened for injecting the foaming gas, so that the foaming gas can be easily injected into the resin material without increasing the injection pressure. Moreover, the sealing function of the dullage section prevents the foaming gas from flowing back to the supply side of the resin material. Therefore, the supply pressure of the resin material and the injection pressure of the foaming gas can be easily adjusted.
Further, the supply pressure of the resin material is released, and the foaming gas is reasonably injected into the portion where the supply pressure of the resin material has become low through the gas injection passage, and does not flow backward, and flows directly to the die outlet of the extrusion die. It doesn't get lost.

As described in claim 2, wherein the throttle member is a cylindrical shape having the same outer diameter as the screw width longer axial length than the wings of the screw blade, said screw shaft on an outer peripheral portion It is desirable that a plurality of groove portions that are inclined with respect to the axis be provided.

  With this configuration, the dullage section that has a simple structure of providing the throttle member locally increases the supply pressure of the resin material in the cylinder and locally increases the supply pressure of the resin material in the cylinder to exert the sealing function. Is formed.

  As described in claim 3, it is preferable that the gas injection passage is formed so as to be inclined from the foaming gas supply passage toward the throttle member in the foaming gas injection section.

  By doing so, the supply pressure of the resin material is released, and the foaming gas is reasonably injected into the portion where the supply pressure of the resin material becomes low through the gas injection passage, and does not flow backward, and the die outlet of the extrusion die It doesn't flow as it is.

  As described in claim 4, it is preferable that the surface of the screw shaft at which the downstream end of the gas injection passage is open is the shaft surface on the upstream side of the screw blade and is in the vicinity of the screw blade.

  With this configuration, the foaming gas can be injected into the resin material without increasing the injection pressure.

  As described in claim 5, it is desirable that a barrier flight section that stably supplies the resin material and the foaming gas by the screw is disposed downstream of the foaming gas injection section.

  In this way, the injected foaming gas is smoothly supplied together with the resin material.

  As described in claim 6, a full-flight short-pitch section is disposed downstream of the barrier flight section to increase the cylinder internal pressure and highly compress the resin material and the foaming gas into an extrusion die. It is desirable that

  In this way, the foaming gas is confined in the resin material by high compression to form bubbles and become foamed resin.

  As described in claim 7, in the extrusion die, it is preferable that a passage through which a mixture of the resin material and the foaming gas flows is bent at an angle with respect to an axis of the screw shaft.

  In this way, the foaming gas is trapped, the resin material collides with the bent portion, and the miniaturization of the bubbles of the foamed resin is promoted.

  The present invention, in the foaming gas injection section, which is a portion where the supply pressure of the resin material is released and is the downstream side of the dullage section for locally increasing and sealing the supply pressure of the resin material in the cylinder, Since the gas injection path is opened to inject the foaming gas, by adjusting the supply pressure of the resin material and the injection pressure of the foaming gas, it is easy to inject the foaming gas into the resin material, And it can be done reliably.

1 is a vertical cross-sectional view showing an embodiment of a foamed resin extrusion device according to the present invention. It is sectional drawing in the AA line of FIG. It is sectional drawing in the BB line of FIG. It is an enlarged view of the C section of FIG. It is an enlarged view of the D section of FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a vertical sectional view showing an embodiment of a foamed resin extrusion device according to the present invention.

  Reference numeral 1 denotes a foamed resin extruding device, which has a cylinder 3 in which a rotatable screw 2 is arranged, and a resin material supplied into the cylinder 3 is fed by rotating the screw 2 while foaming gas ( For example, air, carbon dioxide) is injected, mixed (kneaded) with each other, sent to the die outlet 3a side of the extrusion die 3 and extruded as a porous thermoplastic synthetic resin.

  The resin material is introduced through the hopper 4 in which the resin material supply port 4a opening in the cylinder 3 is opened and closed by a resin material introduction shutter (not shown). The foaming gas is supplied by the compressor 5 through the foaming gas passage 6.

  An extrusion die 8 is connected to the cylinder outlet 3a via an adapter 7, and is extruded as foamed resin through the die outlet 8a of the extrusion die 8. Since the die passage 8b formed in the extrusion die 8 is bent at an angle (in this embodiment, approximately 90 degrees) with respect to the axis of the screw shaft 2a, it exits the cylinder outlet 3a. The mixture of the resin material and the foaming gas collides with the passage wall of the die passage 8b, is bent in the traveling direction and is extruded.

  The screw 2 has a screw blade 2b spirally provided around a screw shaft 2a.

  The bubbling gas passage 6 has a passage portion 6a formed at the axis of the screw shaft 2a and a passage portion 6b which is in communication with the passage portion 6a and is arranged outside. Further, the screw shaft 2a has a gas injection passage 6c having an upstream end (in the direction in which the foaming gas flows) communicates with the passage portion 6a (foaming gas passage 6) and a downstream end opening to the surface of the screw shaft 2a. It is provided. A bubbling gas pressure booster 9 is provided in the middle of the passage portion 6b, and the bubbling gas pressure booster 9 controls the injection pressure to increase or decrease the bubbling gas injection pressure. It is like this.

  The structure of the screw 2 is changed to facilitate pressure control of the supply pressure of the resin material in the cylinder 3 and the injection pressure of the foaming gas to be injected. As a result, four sections are provided in the cylinder 3 in addition to the normal supply section S having the same screw structure as the conventional one. That is, the dullage section S1, the foaming gas injection section S2, the barrier flight section S3, and the full flight short pitching section S4 are sequentially arranged. In the barrier flight section S3 and the full flight short pitching section S4, the outer diameter of the screw shaft 2a is larger than those of the normal supply section S, the dullage section S1 and the foaming gas injection section S2.

  In the dullage section S1, a throttle member 11 for increasing the supply pressure of the resin material is provided on the screw shaft 2a. As a result, by locally increasing the supply pressure of the resin material in the cylinder 3 to exert the sealing function, the foaming gas is prevented from flowing back to the material supply port 4a side.

  The throttle member 11 has a cylindrical shape whose outer diameter is substantially the same as the outer diameter of the screw blade 2b and has an axial length longer than the width of the screw blade 2b, and is provided on the screw shaft 2a. The throttle member 11 is provided with a plurality of groove portions 11a that are inclined with respect to the axis of the screw shaft 2a on the outer peripheral portion. Since the axial length of the throttle member 11 is considerably larger than the width of the screw blade 2b, the supply pressure is increased when the resin material passes between the throttle member 11 and the inner peripheral wall of the cylinder 3. As described above, the supply pressure of the resin material is increased in the dullage section S1, and the resin material is sent out to the foaming gas injection section S2.

  In the foaming gas injection section S2, the screw structure is returned to the same structure as the normal supply part S, so that the supply pressure of the resin material decreases after passing between the throttle member 11 and the inner peripheral wall of the cylinder 3. This prevents backflow of the resin material. Further, since the foaming gas is injected through the gas injection passage 6c at an injection pressure higher than the lowered supply pressure, the resin material is prevented from flowing into the gas injection passage 6c, and the injection of the foaming gas becomes easy. The gas injection path 6c is formed so as to extend obliquely toward the throttle member 11, and the upstream end has an upstream axial surface (in the resin material flow direction) of the screw blade 2b in which the supply pressure of the resin material is low. Therefore, it opens in the vicinity of the screw blade 2b. Here, since the foaming gas is injected into the portion where the supply pressure of the resin material is low and is not easily affected by the supply pressure of the resin material, the injection pressure does not need to be high and the injection pressure can be controlled. Is easy.

  The barrier flight section S3 stably supplies the resin material while mixing (kneading) it with the injected foaming gas, and the full flight short pitching section S4 increases the cylinder internal pressure to highly compress the foaming gas and the resin material. As a result, the foaming gas is confined in the resin material to form bubbles and become foamed resin.

  Since the extrusion die 8 is connected to the cylinder outlet 3a via the adapter 7, the foamed resin collides with the bent portion of the die passage 8b in the extrusion die 8 and is trapped in the resin material. The miniaturization of the foaming gas is promoted, and finally it is extruded as a porous foamed resin through the die outlet 8a to the outside. The degree of miniaturization of the foaming gas can be adjusted by changing the bending angle of the die passage 8b.

  According to the above apparatus, first, the rotation speed of the screw 2 is set according to the supply pressure of the resin material. The foaming gas pressure booster 9 raises the foaming gas to a predetermined pressure and injects it through the foaming gas passage 6. Regarding the rotation speed of the screw 2 (supply pressure of the resin material) and the injection pressure of the foaming gas, various combinations of beta bases have been prepared in advance by experiments. The relationship between the supply pressure of the resin material and the injection pressure of the foaming gas can be adjusted by selecting the combination of the rotation speed and the pressure from the database.

  When the resin material is supplied into the cylinder 3 through the material supply port 4a of the hopper 4, first, the normal supply section S sends the resin material to the extrusion die 8 side. Since the resin supply pressure is increased in the dullage section S1 and released in the foaming gas injection section S2 subsequent to the dullage section S1, the resin supply pressure is reduced, so that the foaming gas in the cylinder 3 passes through the gas injection path 6c. And mixed with the resin material. At this time, the gas injection path 6c is formed so as to be inclined toward the throttle member 11, and the surface of the screw shaft 2a in the foaming gas injection section S2 (the screw blade 2b upstream shaft surface where the resin supply pressure becomes particularly low). Since it is opened in the vicinity of the screw blade 2b), the foaming gas is smoothly injected and does not flow to the die outlet 8a of the extrusion die 8 as it is, even if the injection pressure is not so high. Further, since the dullage section S1 locally increases the supply pressure of the resin material and exerts a sealing function, the foaming gas may flow over the dullage section S1 to the material supply port 4a side of the hopper 4. There is no.

  In the barrier flight section S3 following the foaming gas injection section S2, the mixed foaming gas and the resin material are stably supplied by the screw 2, and in the next full flight short pitching section S4, the internal pressure of the cylinder 3 is increased to foam. By highly compressing the working gas and the resin material, the foaming gas is confined in the resin material, and the foaming gas is made into a large number of bubbles to form a foamed resin.

  Then, the foamed resin supplied to the extrusion die 8 collides with the bent portion of the die passage 8b, which promotes the miniaturization of the bubbles (foaming gas) trapped in the resin material, and finally the finer particles. It is extruded from the die outlet 8a as a porous foamed resin which is a foamed resin having bubbles.

  Although the preferred embodiments of the present invention have been described above with reference to the drawings, various additions, changes, or deletions can be made without departing from the spirit of the present invention.

1 Foamed Resin Extruder 2 Screw 2a Screw Shaft 2b Screw Blade 3 Cylinder 3a Cylinder Exit 4 Hopper 4a Material Supply Port 5 Compressor 6 Foaming Gas Passages 6a, 6b Passage 6c Gas Injection Passage 8 Extrusion Die 8a Die Exit 8b Die Passage 9 Foaming gas pressure booster 11 Throttling member 11a Groove S Normal supply part S1 Dullage section S2 Foaming gas injection section S3 Barrier flight section S4 Full flight Short pitching section

Claims (6)

It has a cylinder in which a screw in which screw blades are spirally wound is arranged inside a screw shaft, and a foaming gas is injected while the resin material supplied into the cylinder is sent by rotating the screw. Then, by mixing them, a foamed resin extrusion device for extruding as a porous thermoplastic synthetic resin through a die outlet of an extrusion die,
The screw shaft of the screw includes a foaming gas supply passage extending in the axial direction, and a gas injection passage having an upstream end communicating with the foaming gas supply passage and a downstream end opening to the surface of the screw shaft. ,
In the cylinder, a dullage section that locally increases the supply pressure of the resin material and exhibits a sealing function is formed, and in the downstream side of the dullage section, the part where the supply pressure of the resin material is released and decreases A foaming gas injection section is provided at which a downstream end of the gas injection path is opened and the foaming gas is injected .
The dullage section is provided with a throttle member that locally increases the supply pressure of the resin material on the screw shaft of the screw,
In the foaming gas injection section, the gas injection path is formed so as to extend from the foaming gas supply path toward the throttle member in an inclined manner . The throttle member has a cylindrical shape having an outer diameter that is the same as the outer diameter of the screw blade and an axial length that is longer than the width of the screw blade, and a plurality of members that are inclined with respect to the axis of the screw shaft in the outer peripheral portion. The foamed resin extrusion device according to claim 1, wherein the groove portion is provided. The foamed resin extrusion device according to claim 1 or 2 , wherein a surface of the screw shaft at which a downstream end of the gas injection path is open is a shaft surface on the upstream side of the screw blade and near the screw blade. Wherein the downstream side of the blowing gas injection section, foam according to any one of said resin materials wherein a foaming gas stably supplying barrier flight section is arranged by the screw, according to claim 1 to 3 Resin extrusion equipment. The foamed resin according to claim 4 , wherein a full flight short pitch section is disposed downstream of the barrier flight section to increase a cylinder internal pressure and highly compress the resin material and the foaming gas to extrude them into an extrusion die. Extruder. The extrusion die, the mixture flows passage between the resin material and the foaming gas is bent at an angle to the axis of the screw shaft, according to any one of claims 1 to 5 Foam resin extrusion equipment.

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