JP3016711B2 - Degassing method in extrusion molding and venting device of extruder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degassing method and a venting device for an extruder having a venting device for degassing a plasticized molding material.

[0002]

2. Description of the Related Art In an extruder, a molding material is plasticized in a barrel, and a screw provided in the barrel is rotated to extrude the kneaded plasticized material (hereinafter referred to as "molten resin"). The molten resin is supplied to a mold provided at the tip of the barrel. Here, as shown in FIG. 2, in order to remove volatile substances, moisture, and the like contained in the molten resin generated by the kneading action of the screw 112 (hereinafter, referred to as “degassing”), the barrel 111 is provided halfway. Is
Opening 1 for communicating the inside and outside of barrel 111
A vent device 115 is provided which has a basic configuration of a cylindrical metal member 116 formed with 16a. In addition, a vacuum device (not shown) is connected to the vent device 115, and forcibly discharges volatile substances, moisture, and the like coming out of the barrel 111 from the opening 116a.

[0003]

However, in the above-mentioned conventional venting apparatus, as the extruder continues to operate, as shown in FIG. Block the part 116a,
Eventually, there is a problem in that the pressure difference between the inside and the outside of the barrel 111 causes the molten resin 119 attached to the opening 116a to swell, that is, a so-called vent-up occurs. If venting occurs, not only will degassing not be performed, but also the extruder will not be able to operate normally, and operation will have to be interrupted for maintenance of the extruder, which will significantly impede production efficiency. Become.

Further, since the temperature of the metal in the vent apparatus depends on the temperature of the barrel and is relatively high, if the molten resin adheres to the metal, so-called "burn" may occur in the adhered molten resin. As a result, the molten resin deteriorates. And
If the resin in which "burn" has occurred or the deteriorated resin is detached from the metal and mixed into the molded product, the quality of the molded product will be degraded.

Accordingly, an object of the present invention is to provide a degassing method and a venting device which prevent the molding material from adhering to the opening of the venting device and prevent "burn" and deterioration of the molding material. .

[0006]

According to the present invention, there is provided a deaeration method in extrusion molding according to the present invention, wherein an opening communicating between the inside and the outside of the barrel is formed in the middle of the barrel containing the screw. In the deaeration method of discharging the volatile matter of the molding material from the opening of the vent device, during extrusion molding using an extruder that plasticizes and sends out the molding material by rotation of the screw, comprising a vent device. During the extrusion of the molding material, a contact portion of the vent device with the molding material is cooled.

[0007] The vent device of the present invention is provided in the extruder, which plasticizes and sends out the molding material by rotation of the screw, in the middle of the barrel containing the screw to degas the volatile matter of the molding material. A vent device having a metal part having an opening communicating the inside and the outside of the barrel, wherein the metal part has a cooling means for cooling a contact part between the metal part and the molding material. And

[0008] The cooling means may be a cooling fluid chamber formed in the hardware and supplied with a cooling fluid therein.

[0009]

According to the degassing method of the present invention constituted as described above, when the plasticized molding material is carried by the rotation of the screw of the extruder and reaches the opening of the vent device, the volatilization contained in the molding material is removed. Volatiles such as substances and moisture are discharged from the openings.

[0010] At this time, the plasticized molding material comes into contact with the vent device, but the contact portion of the vent device with the molding material is cooled. A cured film is formed on the contact surface with the vent device. As a result, the molding material is prevented from adhering to the vent device, and as a result, venting is prevented. Further, even if the molding material comes into contact with the vent device, since the vent device is cooled, “burning” or deterioration does not occur in the contacting molding material. Therefore, even if the molding material in contact with the vent device is mixed into the molded product, the quality of the molded product does not deteriorate.

[0011]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of an extruder equipped with one embodiment of a vent apparatus of the present invention.

As shown in FIG. 1, an extruder 10 used in this embodiment has two screws 12 in a barrel 11.
Is a two-screw extruder 10. Since the configuration of the extruder 10 is the same as that of the conventional extruder, the description thereof is omitted. In this embodiment, the twin-screw extruder 10 is used. However, the present invention is not limited to this, and a single-screw extruder or a multi-screw extruder may be used.

In the middle of the barrel 11 of the extruder 10, a vent device 15 is mounted. The vent device 15 has a basic configuration of a cylindrical metal member 16 having an opening 16a communicating the inside and the outside of the barrel 11 as in the related art. Inside the hardware 16, a cooling fluid chamber 16b through which a cooling fluid supplied from the outside passes is formed.
The cooling fluid chamber 16b is provided near the bottom of the hardware 16 in order to effectively cool the portion where the molten resin conveyed in the barrel 11 comes into contact by the rotation of the screw 12.
The cooling fluid chamber 16b communicates with an inlet 16c and an outlet (not shown) that are open at the upper end of the hardware 16, and the cooling fluid is supplied from the inlet 16c to the cooling fluid chamber 16b, and the cooling fluid is supplied from the outlet. Go outside. Water at 5 to 80 ° C. or warm water is used as the cooling fluid. In addition, a vacuum device (not shown) is connected to the vent device 15 as in the related art.

When resin is extruded based on the above structure,
The resin supplied into the barrel 11 is plasticized and kneaded by heating the barrel 11 and rotating the screw 12, and is conveyed to the front of the barrel 11. This plasticization turns the resin into a molten resin. When the molten resin reaches the opening 16a of the vent device 15, the pressure is released at this point, and volatile components such as volatile components and water contained in the molten resin are separated and discharged from the opening 16a.

At this time, the molten resin comes into contact with the metal 16, but since the metal 16 is cooled by the cooling fluid flowing through the cooling fluid chamber 16 b, the contact surface of the molten resin with the metal 16 at the moment of contact with the metal 16. Forms a cured film.
As a result, the molten resin does not adhere to the hardware 16 and venting is prevented. Further, since the surface of the metal object 16 is cooled, even if the molten resin comes into contact with the metal object 16, "burn" or deterioration does not occur in the contacted molten resin. Therefore, even if the molten resin in contact with the hardware 16 is carried by the rotation of the screw 12 and is mixed into the molded product, the quality of the molded product is not reduced.

ABS (acrylonitrile.
Butadiene / styrene copolymer resin), AS (acrylonitrile / styrene copolymer resin), EEA (ethylene / ethyl acrylate copolymer resin), EVA (ethylene / vinyl acetate copolymer resin), PBT (polybutylene terephthalate), PP ( Polypropylene). That is, if the present invention is applied to the extrusion molding of these resins, the above-described effects are more remarkably exhibited.

[0018]

The degassing method and the vent device of the present invention are as follows.
As described above, by cooling the contact portion with the molding material, it is possible to prevent the molding material from adhering to the vent device. As a result, vent-up is prevented, and the trouble of the extruder associated therewith can be reduced, so that a wide range of operation of the extruder can be secured. In addition, even if the molding material comes into contact with the vent device, "burn" occurs in the molding material,
A high quality molded product can be obtained without deterioration of the molding material.

[Brief description of the drawings]

FIG. 1 is a sectional view of a barrel of an extruder equipped with an embodiment of a vent device of the present invention.

FIG. 2 is a sectional view of a barrel of an extruder equipped with a conventional vent device.

FIG. 3 is a cross-sectional view for explaining a vent-up occurring in the vent device shown in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Extruder 11 Barrel 12 Screw 15 Vent device 16 Hardware 16a Opening 16b Cooling fluid chamber 16c Inlet

Continuation of the front page (56) References JP-A-58-3845 (JP, A) JP-A-61-266221 (JP, A) JP-A-1-310925 (JP, A) JP-A-8-244097 (JP) , A) JP-A-8-267537 (JP, A) JP-A-60-62921 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 47/00-47/96

Claims (2)

(57) [Claims] A twin screw (12) rotating in the same direction.
In the middle of the barrel (11) of the extruder (10) which plasticizes and sends out the molding material supplied into the barrel (11), a metal (16) for degassing the volatile matter of the molding material is inserted. In the vent device (15), the hardware (1)
6) The screw (1) on the rotation direction side of the twin screw
2) an opening (16a) extending upward from near the biting side contact point between the barrel and the barrel (11) and having an arc-shaped curved surface having a radius of curvature larger than the radius of curvature of the screw outer diameter; A cooling fluid chamber (16b) is provided in close proximity to the venting device. 2. The cooling fluid chamber (1) of the hardware (16).
6b), the cooling fluid inlet (16)
The venting device for an extruder according to claim 1, wherein c) is provided.