JPH07237218A - Extruding kneader for rubber-like material - Google Patents

Abstract

PURPOSE:To remove a shear flow by separating a rubber-like material from an extru sion passage by a method wherein a porous die is fitted to an extrusion head, a conver gent extrusion passage through which the rubber-like material passes is provided on the die, and besides a fluid passage is formed to make the fluid flow out onto the surface of the extrusion passage from the fluid passage. CONSTITUTION:A truncated cone like die 31 is fitted to an extrusion head 30 attached to a tip part of a casing 26 of a kneader 25. The die 31 is composed of sintered metal, and besides a through convergent conical extrusion passage 32 is formed. A plurality of ring like grooves 38 extending continuously in a peripheral direction are formed between the extrusion head 30 and an outer peripheral part of the die 31, and a plurality of annular grooves 39 are connected to the ring like grooves 38 by passages 40 also on an outer periphery of the head 30. Therefore, high pressure fluid from the annular groove 39 connected to a high pressure fluid source is introduced to the whole of the outer periphery of the die 31 from a fluid passage 41 consisting of the annular groove 39, the passage 40, and the ring like groove 38, and made to flow out uniformly on the surface of the extrusion passage 32 from many holes of the die 31. Then, extruded rubber-like material G is separated from the passage 32, and a shear flow is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion kneader for kneading a rubber-like material while extruding it.

[0002]

2. Description of the Related Art Generally, in the tire industry, a kneading mixer having a pair of rotating rotors is used for kneading a rubber-like material used for manufacturing a pneumatic tire, and the kneading mixer discharges from the kneading mixer. An extruder for extruding the obtained rubber-like material into a cross-sectional shape that facilitates handling in the next step is used. Here, since the kneading mixer as described above has a relatively low kneading efficiency, it is necessary to carry out kneading for a long time or repeatedly kneading until a predetermined kneading degree is reached.

For this reason, conventionally, it has been considered that the extruder is provided with a kneading function in order to assist the kneading of the kneading mixer. For example, the shape of the screw of the extruder is devised so that the extruder is made into a rubber-like material. It was proposed that kneading be carried out during the transfer of the objects.

[0004]

However, although such a conventional extruding and kneading machine for a rubber-like material can be expected to have a certain kneading effect, it has not been said to be sufficient yet.

[0005]

Therefore, the present inventor has
Research was conducted on how kneading is performed in such an extrusion kneader. In the process of this research, kneading is performed to some extent even when the rubber-like material is extruded from the extrusion head of the extrusion kneader, and such kneading is performed by extruding the rubber-like material G and the extrusion head 11 as shown in FIG. aisle
Due to the frictional resistance with the surface of 12, the flow velocity of the rubber-like material G decreases toward the surface of the extrusion passage 12 and a velocity gradient is generated, whereby the rubber-like material G shears and flows in the flow direction. It has been found that when the rubber-like material G passes through the extruding passage 12, the rubber-like material G is stretched in the axial direction while becoming thin, whereby the rubber-like material G is stretched and fluidized. Here, when the kneading efficiency due to extensional flow (value obtained by dividing the progress of kneading by the energy consumed during kneading) and the kneading efficiency due to shear flow were measured, the former was almost three times that of the latter. I found out that. Therefore, in order to improve the kneading efficiency of the rubber-like material G when the energy consumption is constant, the present inventor reduces the shear flow ratio of the rubber-like material G at the time of extrusion to reduce the elongation flow. He came up with the idea of increasing the ratio.

The present invention was made on the basis of the above-mentioned findings, and a casing having an extruding chamber into which a rubber-like material is placed and a rubber-like material in the extruding chamber are pressed and moved toward the downstream side. What is claimed is: An extrusion kneader of a rubber-like material comprising a pressing movement mechanism and an extrusion head provided at a downstream end of a casing, wherein a die made of a porous material is attached to the extrusion head, and a downstream side of the die. Forming a penetrating extrusion passage through which the rubber-like material passes toward the die, and further forming a fluid passage in the extrusion head for guiding the fluid to the die, and when the rubber-like material is extruded through the extrusion passage, The fluid from the passage is made to flow through the inside of the die to the surface of the passage, and the outflowing fluid separates the rubber-like material from the surface of the passage.

[0007]

Now, it is assumed that the rubber-like material charged into the extrusion chamber of the casing is pressed by the operation of the pressing movement mechanism to move to the downstream side and is extruded through the extrusion passage of the die attached to the extrusion head. . At this time, since the die is made of a porous material and the fluid is guided to the die through the fluid passage, the fluid from the fluid passage flows out to the surface of the extrusion passage through the inside of the die, thereby extruding the fluid. A film of the effluent fluid is formed on the surface of the passage to isolate the rubbery material from the surface of the extrusion passage. Here, the fluid from the fluid passage flows out almost uniformly to the surface of the extrusion passage because the die is made of a porous material, and as a result, the film of the outflow fluid does not lose the entire surface of the extrusion passage. Spread to. As a result, the rubber-like material is isolated from the entire surface of the extrusion passage, so that the frictional contact between the rubber-like material and the extrusion passage as the rubber-like material passes through the extrusion passage is reduced as much as possible. Here, since the extrusion passage is tapered toward the downstream side, it is considered that both the shear flow and the extension flow occur in the rubber-like material when passing through the extrusion passage. As described above, since the frictional contact between the rubber-like material and the extrusion passage is minimized as much as possible, shear flow hardly occurs in the rubber-like material,
The stretching flow, which becomes thin and is stretched in the axial direction, becomes the majority. Since the kneading efficiency due to such extensional flow is approximately three times as high as the kneading efficiency due to shear flow as described above, as a result, the kneading efficiency of the rubber-like material is improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 21 is a kneading mixer generally called an internal mixer, and a pair of rotors 22 are housed in the kneading mixer 21.
22 is driven and rotated by a drive mechanism (not shown),
The rubber-like material G, for example, rubber alone or rubber (dispersion medium) mixed with a small amount of sulfur, carbon or the like (dispersion phase) is kneaded. When the rubber-like material G is kneaded to a predetermined kneading degree, the rubber-like material G is discharged from the lower part of the kneading mixer 21. Here, the kneading mixer 21 as described above generally has a relatively low kneading efficiency, and as a result, in order to knead up to a predetermined kneading degree (plasticity, dispersity), the rubber-like material G is kneaded for a long time or repeatedly. There is a need.

An extrusion kneader 25 having a horizontal casing 26 is installed immediately below the kneading mixer 21. Inside the casing 26 of the extrusion kneader 25, the kneading mixer is provided.
An extrusion chamber 27 into which the rubber-like material G discharged from 21 is charged is formed. Further, a screw 28 as a rotatable pressing movement mechanism is housed in the extrusion chamber 27, and the screw 28 is rotated by a rotating means (not shown). Then, when the screw 28 rotates, the rubber-like material G in the extrusion chamber 27 of the casing 26 is pressed and moved toward the downstream side (forward), and at this time, the rubber-like material G is kneaded to some extent.

Reference numeral 30 denotes an extrusion head attached to the downstream end (front end) of the casing 26. A frustoconical die 31 is attached to the extrusion head 30, and the die 31 has a large number of fine insides. It is composed of a porous material having holes formed therein, for example, a sintered metal. The die 31 is formed with an axially extending through extrusion passage 32, and the extrusion passage 32 has a substantially conical shape tapering toward the downstream side. Here, the cross-sectional area of the extrusion chamber 27 immediately after the extrusion head 30 is defined by the minimum cross-sectional area at the tip (downstream end) 32a of the extrusion passage 32 (the total of these when a plurality of extrusion passages 32 are provided). The divided value Z is 20 in order to make the kneading based on extensional flow effective.
The above is preferable. A mouthpiece 33 is attached to the front surface of the extrusion head 30, and an opening 34 communicating with the extrusion passage 32 is formed in the mouthpiece 33. The rubber-like material G pushed and moved by the screw 28 is pushed out through the extrusion passage 32 of the die 31, and then the die 33
By passing through the opening 34, it is formed into a cross-sectional shape that can be easily handled in the next step.

A plurality of ring-shaped grooves 38 are formed between the extrusion head 30 and the outer periphery of the die 31 so as to be apart from each other in the axial direction and continuously extend in the circumferential direction. A plurality of annular grooves 39 extending axially apart from each other and extending continuously in the circumferential direction are also formed therebetween. The annular grooves 39 and the ring-shaped groove 38 are formed in the extrusion head 30 and extend in a substantially radial direction. Connected by 40. Here, the annular groove 39 has a high pressure (not shown), for example, 25 kgf.
/ cm ² or more of the fluid source, for example, a source of water, air, nitrogen gas, etc., so that the high-pressure fluid from the high-pressure fluid source consists of an annular groove 39, a passage 40 and a ring-shaped groove 38 It is guided to the entire outer circumference of the die 31 through the fluid passage 41. Then, the high-pressure fluid thus guided to the die 31 flows out to the surface of the fluid passage 36 almost uniformly through the numerous fine holes in the die 31.

Next, the operation of the embodiment of the present invention will be described. Now, the rotor 22 of the kneading mixer 21 is rotated, and the rubber-like material G in the kneading mixer 21 is kneaded, that is, when it is rubber, it is plasticized, and when a chemical is mixed,
It is assumed that the contact area between the dispersion medium constituting the rubbery material G and the dispersed phase is increased and dispersion is performed. Next, when such a rubber-like material G is kneaded to a predetermined kneading degree, the rubber-like material G is discharged from the kneading mixer 21 and put into the casing 26 of the extrusion kneader 25. At this time, the extruder kneader 25
Since the screw 28 is rotating, the rubber-like material G charged in the extrusion chamber 27 is pressed and moved to the downstream side,
It is extruded through the extrusion passage 32 of 31.

At this time, since the die 31 is made of a porous material and the high pressure fluid is guided to the die 31 through the fluid passage 41, the high pressure fluid from the fluid passage 41 passes through the fine holes in the die 31. It flows out to the surface of the extruding passage 32, whereby a film R of the outflow fluid is formed on the surface of the extruding passage 32 and the rubber-like material G is isolated from the surface of the extruding passage 32. Here, since the die 31 is made of a porous material, the fluid from the fluid passage 41 flows out almost uniformly to the surface of the extrusion passage 32, and as a result, the film R of the outflow fluid is extruded without loss. Spread over the entire surface of passage 32. As a result, the rubber-like material G is separated from the entire surface of the extrusion passage 32,
As a result, the rubber-like material G when passing through the extrusion passage 32
The frictional contact between the extrusion passage 32 and the extrusion passage 32 is reduced as much as possible.
Since the extrusion passage 32 through which the rubber-like material G passes is tapered toward the downstream side, the rubber-like material G when passing through the extrusion passage 32 has shear flow and expansion as described above. It is thought that both flow and flow will occur,
As described above, since the frictional contact between the rubber-like material G and the extrusion passage 32 is reduced as much as possible, almost no shear flow occurs in the rubber-like material G, and the flow generated in the rubber-like material G becomes thin. Most of the extensional flow is stretched in the axial direction. Since the kneading efficiency by the extensional flow is almost three times as high as the kneading efficiency by the shearing flow as described above, as a result, the kneading efficiency of the rubber-like material G is improved, and the load of the kneading mixer 21 is thereby increased. Is reduced and the work efficiency of the kneading apparatus as a whole is improved. After that, the rubber-like material G passes through the opening 34 of the die 33 to be molded into a cross-sectional shape that can be easily handled in the next step. On the other hand, the above-described fluid film R extrudes the rubber-like material G, the passage 32, and the opening 34.
After being moved forward together with the rubber-like material G while being isolated from it, it is discharged from the front end of the opening 34 to the outside, so that it does not remain in the rubber-like material G.

Next, a test example will be described. In this test, a conventional extrusion head as shown in FIG. 3 and a test extrusion head as shown in FIG. 2 were prepared, and these extrusion heads were mounted on an extrusion kneader to mix carbon and the like. The extrudates were extruded under the same extrusion (consumption) energy. Then, the electrical resistance value of the rubber-like material extruded from both extrusion heads was measured, and the dispersity of carbon (kneading degree of the rubber-like material) was determined. The result is 30k for a rubber-like material extruded from an extrusion head.
Although it was Ω, the rubber-like material extruded from the test extrusion head was 80 kΩ, and the dispersity (kneading degree) was significantly improved.

In the above-mentioned embodiment, the extrusion kneader 25 is used as an auxiliary for kneading of the kneading mixer 21, but as an independent extrusion kneader only kneading a rubber-like material, or a tread rubber or the like. May be used as an independent extruder for further kneading during extrusion. In addition, in the above-described embodiment, the extrusion head
Although one die 31 is attached to 30, two or more dies may be attached in the present invention. Further, in the above-described embodiment, the screw 28 is used as the pressing movement mechanism, but in the present invention,
A piston that moves in the casing 26 in the axial direction may be used.

[0016]

As described above, according to the present invention, the kneading efficiency in the extruder for kneading the rubbery material can be further improved.

[Brief description of drawings]

FIG. 1 is a schematic front sectional view showing an embodiment of the present invention.

FIG. 2 is a front sectional view in the vicinity of a die.

FIG. 3 is a front sectional view in the vicinity of an extrusion head in a conventional extrusion kneader.

[Explanation of symbols]

 25 ... Extrusion kneader 26 ... Casing 27 ... Extrusion chamber 28 ... Pressing movement mechanism 30 ... Extrusion head 31 ... Die 32 ... Extrusion passage 41 ... Fluid passage G ... Rubber-like material

Claims (1)

[Claims] 1. A casing in which an extruding chamber into which a rubber-like material is put is formed, a pressing moving mechanism for pressing and moving the rubber-like material in the extruding chamber toward a downstream side, and a casing provided at a downstream end of the casing. A kneader for extruding a rubber-like material having an extruding head, wherein a die made of a porous material is attached to the extruding head, and a penetrating taper of the rubber-like material passes through the die toward the downstream side. And a fluid passage that guides fluid to the die is formed in the extrusion head.When the rubber-like material is extruded through the extrusion passage, the fluid from the fluid passage is extruded through the inside of the die. An extruding kneader for a rubber-like material, characterized in that the rubber-like material is allowed to flow out to the surface and the rubber-like material is isolated from the surface of the extrusion passage by the flowing-out fluid.