JPH115245A - Extruder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a vent-up from being generated by forming a space part in the upstream side of a vent to generate a bubble and curbing the generation of the bubble in a vent zone. SOLUTION: This extruder comprises a barrel 2 and a screw 3 to be introduced, in a freely rotating manner, into a through hole 2a in the barrel 2, and is constructed of a kneading zone A as a part where a kneading screw 3a is positioned and a molten material conveyance zone B as a part where a conveyance screw 3b is positioned, with a vent 2b communicating with the outside of the barrel 2 formed in the kneading zone A. In this case, a foaming zone D made up of a space part 2c is provided in the upstream position of the vent 2b in the molten material conveyance zone B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an extruder, and more particularly to a novel improvement for preventing a resin material from venting up in a vent zone.

[0002]

2. Description of the Related Art In general, a volatile material is contained in a resin material, and such a resin material is plasticized and kneaded by an extruder provided with a vent portion, and the volatile material is devolatilized and removed. FIG. 2 shows an axial cross-sectional view near the vent portion of a conventional extruder. In the figure, reference numeral 1 denotes an extruder for plasticizing and kneading a resin material, and the extruder 1 includes a barrel 2 and a screw 3 rotatably inserted into a through hole 2a of the barrel 2. ing. The extruder 1 has one or two screws 3 and, when having two screws 3, is configured to rotate in the same direction or different directions in a meshing state or a non-meshing state. . The screw 3 includes a kneading screw 3a at an upstream (left direction in FIG. 2) portion and a transport screw 3b at a downstream (right direction in FIG. 2) portion. In the through hole 2a of the barrel 2, a portion where the kneading screw 3a is located is configured as a kneading zone A, and a portion where the transport screw 3b is located is configured as a melt transport zone B. Above the through hole 2a of the melt transport zone B on the downstream side of the kneading zone A, a vent hole 2b communicating with the outside of the barrel 2 is formed over a predetermined distance, and the vent zone C is formed by the vent hole 2b. Make up. The vent hole 2b is connected to an exhaust device (not shown).

[0003] In the extruder 1 configured as described above, the case where the resin material is plasticized and kneaded and the volatile substances are devolatilized and removed will be described below. While the screw 3 is being driven to rotate by a driving device (not shown),
A resin material is supplied to a through hole 2a from a material supply port (not shown) provided in an upstream portion of the resin material. The resin material supplied into the through hole 2a is sequentially transported downstream in the through hole 2a by the screw 3, and is first plasticized and kneaded in the kneading zone A by the rotating kneading screw 3a. As a result, the resin material is in a molten state in which a volatile substance, entrained air, and moisture (hereinafter, referred to as volatile components, etc.) are kneaded and dispersed. Next, when the resin material in the molten state moves from the kneading zone A to the melt transport zone B, the resin material expands in volume due to foaming of volatile components and the like, and the volatile substance is removed together with other volatile components and the like. Separate from Thereafter, the foamed resin material moves to the vent zone C, and air and moisture containing volatile substances separated by foaming are removed from the vent hole 2 by the exhaust device.
devolatilized and removed from b. The resin material from which the air and water containing volatile substances have been devolatilized and removed passes through the vent zone C and moves further downstream of the melt transport zone B.

[0004]

Since the conventional extruder is configured as described above, there are the following problems. That is, if the foaming is completed before the resin material reaches the vent zone C, the volatile material and the like are separated in the vent zone C, the volume is reduced, and the resin material passes through the vent zone C smoothly. , Melt transport zone B
When the resin material is insufficiently foamed before reaching the vent zone C, the foaming continues even after the resin material reaches the vent zone C. As a result, the resin material swells (vents up) in the vent hole, adheres to the inner surface of the vent hole, closes and covers the entire vent hole, and devolatilization sometimes becomes impossible.

The present invention has been made to solve the above-mentioned problems, and in particular, a space is formed upstream of a vent hole to cause foaming, and foaming in a vent zone is suppressed to increase venting. It is an object to provide an extruder that does not generate any.

[0006]

An extruder according to the present invention comprises:
A barrel, and a screw rotatably inserted into a through hole of the barrel, wherein the screw is configured by a kneading screw at an upstream portion and a transport screw at a downstream portion, and the through hole of the barrel is formed by a screw of the kneading screw. The located portion is a kneading zone, the portion where the transport screw is located is configured as a melt transport zone, the melt transport zone,
In the extruder forming a vent hole communicating with the outside of the barrel to form a vent zone, the extruder having a foaming zone comprising a space portion directed upward on the upstream side of the vent hole in the melt transport zone. is there. further,
The space portion is configured such that the axial length ratio L / D is 0.2 to 2, the depth is within the groove depth of the transport screw, and the axial cross-sectional shape is substantially rectangular.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an extruder according to the present invention will be described below in detail with reference to the drawings. Note that the same or equivalent parts as those in the related art will be described using the same reference numerals. FIG. 1 is an axial sectional view showing the vicinity of a vent portion of an extruder according to the present invention. In the figure, reference numeral 1 denotes an extruder for plasticizing and kneading a resin material. The extruder 1 includes a barrel 2 and a screw 3 rotatably inserted into a through hole 2a of the barrel 2. It is configured. The screw 3 includes a kneading screw 3a at an upstream (left direction in FIG. 1) portion and a transport screw 3b at a downstream (right direction in FIG. 1) portion. The through hole 2a of the barrel 2 is configured such that a portion where the kneading screw 3a is located is a kneading zone A, and a portion where the transport screw 3b is located is a melt transport zone B. Above the through hole 2a of the melt transport zone B (upward in FIG. 1), a vent hole 2b is formed over a predetermined distance.
Is composed. The vent hole 2b is connected to an exhaust device (not shown).

In the through hole 2a of the melt transport zone B, a space 2c having a depth in the upper direction is formed at a predetermined distance in the upstream direction from the upstream end of the vent hole 2b, and the foaming zone D is formed. Make up. As the specific shape of the space 2c, the axial length ratio L / D (L is the axial length, and D is the outer diameter of ) Is set to 0.2 to 2, the depth is set to be within the groove depth of the transport screw 3b, the width is set to be within the width of the through hole 2a, and the axial cross-sectional shape is substantially rectangular.

In the extruder 1 configured as described above, a case will be described in which the resin material is plasticized and kneaded to devolatilize and remove volatile substances. In a state where the screw 3 is rotationally driven by a driving device (not shown), a through-hole 2 a is provided from a material supply port (not shown) provided at an upstream portion of the barrel 2.
To supply the resin material. The resin material supplied into the through-hole 2a is sequentially transported downstream in the through-hole 2a by the screw 3, and is first plasticized and kneaded by the rotating kneading screw 3a in the kneading zone A. As a result, the resin material is in a molten state.

Next, the molten resin material is mixed in kneading zone A.
When the resin material moves from the melt transport zone B to the melt transport zone B, the internal pressure of the resin material is removed, the volatile components and the like expand, the volume expands, and the volatile substances are separated from the resin material together with other volatile components and the like. The resin material whose internal pressure has been removed in the melt transport zone B and has begun foaming has a long residence time in the foaming zone D, during which time it expands sufficiently and foams. Thereafter, the foamed resin material moves to the vent zone C, and air and moisture containing volatile substances separated by foaming are devolatilized and removed from the vent hole 2b by the exhaust device. The resin material from which air and water containing volatile substances have been devolatilized and removed passes through the vent zone C while shrinking in volume, and moves smoothly further downstream of the melt transport zone B.

If the axial length ratio L / D is less than 0.2, the required residence time cannot be obtained, and the expansion of the foaming zone D becomes insufficient, and the foaming becomes insufficient. If the length is longer than 2, the overall length of the extruder 1 is lengthened. Therefore, the axial length ratio L / D is set to 0.2 to 2.

[0012]

Since the extruder according to the present invention is constituted as described above, the following effects can be obtained. (1) By providing a space, that is, a foaming zone,
The foaming of the resin material ends before it reaches the vent zone,
Vent-up does not occur in the vent hole, and smooth operation can be continued without worrying about vent-up. (2) In addition, production of defective quality resin material due to venting up, operation stop of the extruder, removal work of the vented up resin material, and the like are eliminated, and the operation efficiency is improved. (3) It is possible to increase the processing capacity of the resin material.

[Brief description of the drawings]

FIG. 1 is an axial sectional view partially showing a vicinity of a vent portion of an extruder according to the present invention.

FIG. 2 is an axial sectional view partially showing the vicinity of a vent portion of a conventional extruder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Extruder 2 Barrel 2a Through-hole 2b Vent hole 2c Space 3 Screw 3a Kneading screw 3b Transport screw A Kneading zone B Melt transport zone C Vent zone D Foaming zone

Claims (2)

[Claims] A barrel (2) and a through hole (2) of the barrel (2).
a) a screw (3) rotatably inserted into the a), wherein the screw (3) is constituted by a kneading screw (3a) at an upstream portion and a transport screw (3b) at a downstream portion, and
The through-hole (2a) of (2) is configured such that a portion where the kneading screw (3a) is located is a kneading zone (A), and a portion where the transport screw (3b) is located is a melt transport zone (B), In the extruder forming the vent zone (C) by forming a vent hole (2b) communicating with the outside of the barrel (2) in the melt transport zone (B), the melt transport zone (B )), An extruder comprising a foaming zone (D) comprising a space part (2c) directed upward on the upstream side of the vent hole (2b). 2. The space portion (2c) has an axial length ratio L / D of 0.2 to 2, a depth within the groove depth of the transport screw (3b), and a substantially axial cross-sectional shape. The extruder according to claim 1, wherein the extruder has a rectangular shape.