JP4063412B2 - Rubber continuous kneading extrusion equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rubber continuous kneading extrusion apparatus, and a non-vulcanizable rubber composition (adding other compounding agents excluding a vulcanizing agent and a vulcanization accelerator to a raw rubber, such as a reinforcing agent, a filler, a plasticizer, etc. Final rubber kneading in which a vulcanizing agent and a vulcanization accelerator are added and kneaded to a rubber composition obtained by kneading, and an extrusion process in which the obtained vulcanizable rubber composition is extruded into a predetermined cross-sectional shape It is possible to make it continuous.
[0002]
[Prior art]
Extruded rubber products such as tire treads and automobile weatherstrips are made of raw rubber with additives such as reinforcing agents, fillers, and plasticizers using a kneader such as a Banbury mixer. (Excluding accelerators) are blended, kneaded (non-pro rubber kneading) into a sheet, a release agent is added, cooled and stacked, and then the rubber sheet comprising the above-mentioned non-vulcanizable rubber composition is added to the kneader again. Add, add vulcanizing agent and vulcanization accelerator, knead (final rubber kneading), sheet the resulting vulcanizable rubber composition, attach release agent, cool and stack It was supplied to an extruder, extruded into a desired shape, cooled, cut into a desired length, and vulcanized. In foamed molded articles such as weather strips, a foaming agent is added together with the above vulcanizing agent and vulcanization accelerator.
[0003]
However, conventionally, kneading performed by adding a vulcanizing agent to a non-vulcanizable rubber composition, so-called final rubber kneading, is performed batch-wise using a Banbury mixer or kneader at a large capacity at a time, so the calorific value is increased. In addition, it was difficult to uniformly disperse the vulcanizing agent and other chemicals. In addition, since it is difficult to suppress heat generation, particularly in a vulcanizable rubber composition (a short-time vulcanized compounded rubber) that begins to vulcanize in a short time or at a low temperature, burning occurs during kneading, making kneading difficult. It was. In addition, various extruders are used for extrusion, but since the process is performed in a separate process separated from the final rubber kneading process, the vulcanizable rubber composition has changed over time, and the physical properties have become unstable. In addition, in order to make the shape of the extruded product uniform, it is necessary to set the extrusion pressure high, so that the pressure loss when passing through the extrusion head and die increases, and the backflow phenomenon occurs at the tip of the extruder. There is a problem that the temperature rise further increases. In addition, in order to solve the problem of batch kneading, it has been attempted to continuously carry out the above final rubber kneading using a continuous kneader for a resin equipped with a twin screw, but in this case, shear heat generation becomes large. There was a problem that rubber burn occurred.
[0004]
[Problems to be solved by the invention]
According to the present invention, final rubber kneading and extruding in which a vulcanizing agent and a vulcanization accelerator are added to a non-vulcanizable rubber composition and kneading can be continuously performed, heat generation due to kneading is suppressed, and a short time is applied. Even if it is a vulcanized rubber, it can be easily kneaded in a short time without causing burning, and extruded into a vulcanizable rubber after kneading with stable physical properties without changing over time. It is intended to be obtained.
[0005]
[Means for Solving the Problems]
The rubber continuous kneading and extruding apparatus according to the present invention has a rubber supply port and an additive supply port at the base side and the center of the barrel of the continuous kneader, respectively, and the rubber supply port is non-vulcanizable via a quantitative gear pump. A rubber supply device for supplying a rubber composition is connected, a quantitative supply device for a vulcanizing agent and a vulcanization accelerator is connected to an additive supply port, and an extruder or a quantitative gear pump is connected to the discharge side end of the barrel. A vulcanizable rubber composition extrusion die head is connected, and the pressure of the non-vulcanizable rubber composition sent from the rubber supply device to the metering gear pump is controlled to be constant so that the non-vulcanizable rubber composition in the continuous kneader things, a vulcanizing agent and a vulcanization accelerator becomes as kneaded under atmospheric pressure, the above-mentioned continuous kneader is a screw-type continuous kneader uniaxial temperature the kneading screw and barrel respectively It has a knuckle function, and the kneading screw is composed of a feed screw portion in which screw blades are continuous and a kneading portion that is segmented by notching the screw blades. The kneading part is provided in each part except for the rubber supply port and the additive supply port except for the rubber supply port and the additive supply port. A shearing pin protrudes from the inner surface of the barrel surrounding the kneading part so as to enter between the screw blades .
[0006]
In the above structure, the non-vulcanizable rubber composition is supplied from the rubber supply device through the metering gear pump and the rubber supply port to the continuous kneader in a predetermined amount and sent to the discharge side while being kneaded in the continuous kneader. When the non-vulcanizable rubber composition reaches the additive supply port, the vulcanizing agent and the vulcanization accelerator are supplied from the quantitative supply device into the continuous kneader through the additive supply port, This non-vulcanizable rubber composition is added to the discharge side while being kneaded with the vulcanizing agent and the vulcanization accelerator, and one or both of an extruder and a metering gear pump is discharged from the discharge side end. It is sent to the die head for extrusion through both, and is formed into a desired cross-sectional shape and discharged.
[0007]
The non-vulcanizable rubber composition supplied to the continuous kneader is added with a vulcanizing agent and a vulcanization accelerator while passing through the continuous kneader, so-called final rubber kneading is performed. Unlike the formula, rubber is kneaded continuously little by little, and by controlling the amount of rubber supplied to the continuous kneader, the barrel of the continuous kneader is prevented from being filled with the vulcanizable rubber composition, Since the above kneading can be performed under atmospheric pressure, the generation of heat associated with the kneading is suppressed and no burning occurs. And since the vulcanizable rubber composition obtained by kneading is immediately sent to the die head via at least one of an extruder and a metering gear pump, the rubber property does not change with time, and the Mooney viscosity of the vulcanizable rubber, The scorch is stable and the profile accuracy of the extruded product is improved. In addition, an extruder and a metering gear pump can be arranged in order between the continuous kneader and the die head, and the speed of the extruder can be controlled so that the rubber pressure on the discharge side of the extruder is constant. Will improve.
[0008]
As the continuous kneader, a single-screw continuous kneader is used, which is preferable in that the barrel can be opened, cleaning is easy, and handling is easy for continuous rubber kneading. Of course, as usual, the kneading screw and the barrel need only have temperature control functions, but the kneading screw is segmented by cutting the feed screw part where the screw blades are continuous and the screw blades. A kneading portion that reciprocates a distance corresponding to one pitch in the axial direction while rotating in one direction within the barrel, and a shear pin projecting from the inner surface of the barrel surrounding the kneading portion. Among them, for example, “CONEDER” manufactured by BUSS is preferable. By using such a kneader, the vulcanizable rubber composition of the kneading part can be reversed or the edges of the segmented screw blades. And kneading efficiency is improved by cutting with a shear pin. The feed screw portion is provided immediately below the rubber supply port and the additive supply port, and the kneading portion is provided at a portion excluding the rubber supply port and the additive supply port.
[0009]
Further, the rubber supply device may be any device that can continuously supply the non-vulcanizable rubber composition to the metering gear pump and adjust the supply amount according to the rubber pressure on the supply side (inlet side) of the metering gear pump, The screw feeder described later is suitable, but is not limited thereto. The form of the non-vulcanizable rubber composition is preferably in the form of a ribbon or a sheet from the viewpoint of facilitating the adjustment of the supply amount, but is in the form of a lump immediately after being kneaded by a Banbury mixer or other batch kneader. In this case, as a rubber supply device, using a conical feeder in which two cone-shaped screws in the horizontal direction intersect on the small-diameter side, a bulk non-vulcanizable rubber composition is sent to the metering gear pump. This makes it possible to omit the sheet or ribbon forming step.
[0010]
Further, the extruder or metering gear pump connected to the discharge side of the continuous kneader may be any one that can continuously supply a predetermined amount of the vulcanizable rubber composition discharged from the continuous kneader to the die head, Further, an extruder and a metering gear pump can be connected in series for use. The extruder is preferably a screw feeder using one or two screws.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1, reference numeral 10 denotes a kneading screw of a known screw type continuous kneader (“CONEDER” manufactured by BUSS), and a fin-like screw blade 12 made of a thin plate protrudes from the surface of a mandrel 11 capable of adjusting the temperature. Is formed, and penetrates through a cylindrical barrel 13 that can be adjusted in temperature, and is supported in a cantilevered manner by a screw driving device 14, and corresponds to one pitch of a screw blade in the axial direction while rotating in one direction at a predetermined speed. Round the distance. The kneading screw 10 has notches 12a of the screw blades 12 extending over a plurality of pitches at a plurality of locations (three locations in the illustrated example) in the axial direction. In the notches 12a, the screw blades 12 are shown in FIG. The segment 12b is formed as shown in FIG. FIG. 2 shows a configuration in which three notches 12a are provided at equal intervals on the screw blades 12 between one pitch and three segments 12b are formed. In addition, the notch part 12a of adjacent pitch is provided in the same phase.
[0012]
On the other hand, on the upper surface of the barrel 13 (see FIG. 1), a rubber supply port 13a and an additive supply port 13b are provided on the base side (screw drive device 14 side) and the central portion, respectively. In this embodiment, the notch 12a of the screw blade 12 in the kneading screw 10 is provided between the rubber supply port 13a and the additive supply port 13b, and on the right side and the tip of the additive supply port 13b. The screw blades 12 respectively provided immediately below the rubber supply port 13a and the additive supply port 13b, and immediately below the intermediate portion of the additive supply port 13b and the free end are a continuous screw portion without the notch portion 12a. It has become. A plurality of shear pins 13c project from the inner surface of the barrel 13 of the kneading portion where the notches 12a are arranged, and enter between the segments 12b. In addition, the continuous screw portion constitutes the feed screw portion of the kneading screw, and the notch portion 12a extending over a plurality of pitches of the screw blades constitutes the kneading portion. The length of the feed screw portion and the kneading portion and The number can be changed according to the purpose. For example, the feed screw part can be provided only directly below the rubber supply port 13a and the additive supply port 13b, and the rest can be used as the kneading part 12a to increase the kneading effect. .
[0013]
A rubber feeder screw feeder 15 is connected to the rubber supply port 13a via a metering gear pump 16, and a rubber ribbon or rubber sheet 17 made of the non-vulcanizable rubber composition is continuously formed on the screw feeder 15. To be supplied. Reference numeral 18 denotes a supply roller for the rubber sheet 17, which pulls out the rubber sheet 17 from the lower carrier 19 at a predetermined speed. Reference numeral 20 denotes a rubber supply pressure control device, which detects the rubber pressure on the supply side of the metering gear pump 16 with the pressure sensor 21 and shifts the drive motor 15A of the screw feeder 15 according to the magnitude, thereby keeping the rubber pressure constant. To maintain.
[0014]
An additive supply hopper 22 is connected to the additive supply port 13b, and a push screw 23 that is rotated by a motor is inserted inside the additive supply port 13b. A cross-linking agent tank 24 and a metering supply device 25 are arranged above and below the left side of the hopper 22. The cross-linking agent falling from the cross-linking agent tank 24 is received by the metering supply device 25 and measured, and dropped into the hopper 22. The cross-linking agent is kept constant in weight per unit time, and the accelerator tank 26 and the metering supply device 27 are arranged vertically above the opposite right side, and the cross-linking accelerator falling from the accelerator tank 26 is metered in the metering device. 27 is received and weighed to maintain a constant weight per unit time of the crosslinking accelerator dropped onto the hopper 22.
[0015]
The base side of a screw type extruder 28 is connected to the right opening end of the barrel 13 of the screw type continuous kneader, and the die head 30 is connected to the discharge port via a metering gear pump 29 for extrusion. Then, a discharge pressure control device 31 is connected to the drive motor 28A at the upper end of the screw type extruder 28, and the rubber pressure at the discharge end of the screw type extruder 28 is detected by the pressure sensor 32, and according to the size. The drive motor 28A is shifted, and the rubber pressure at the discharge end is kept constant.
[0016]
In the above apparatus, the rubber sheet 17 made of the non-vulcanizable rubber composition is pulled up by the supply roller 18 from the carrier 19 and supplied to the screw feeder 15 located above the base side of the continuous kneader and lowered while being kneaded. Then, it is supplied to the base side of the barrel 13 of the continuous kneader through the fixed gear pump 16. At this time, the rubber pressure on the supply side of the metering gear pump 16 is controlled to be constant as described above.
[0017]
The above-mentioned non-vulcanizable rubber composition that has entered the barrel 13 of the continuous kneader is fed toward the discharge end on the right side by the rotation of the kneading screw 10, and 1 pitch is synchronized with the rotation in the meantime. It reciprocates a considerable distance, and is cut by the edge of the segment 12b of the screw blade 12 and the shear pin 13c on the inner surface of the barrel 13 to be subjected to a shearing action and kneaded. When the non-vulcanizable rubber composition passes under the additive supply port 13b, the vulcanizing agent and the vulcanization accelerator discharged from the upper vulcanizing agent tank 24 and the accelerating agent tank 26 are quantitatively supplied. , 27 and the hopper 22, and continuously fed into the barrel 13 by the pushing screw 23, and added to the non-vulcanizable rubber composition passing through the barrel 13. Therefore, the non-vulcanizable rubber composition proceeds to the discharge side together with the vulcanizing agent and the vulcanization accelerator, and kneaded with the vulcanizing agent and the like while reciprocating and cutting again in the same manner as described above. The vulcanizable rubber composition reaches the discharge side end of the barrel 13.
[0018]
Next, the above vulcanizable rubber composition is discharged to the upper end of the screw type extruder 28, sent by the screw type extruder 28, and extruded from the die head 30 as an extruded product 33 through the metering gear pump 29. In this case, the rubber pressure on the discharge side of the screw type extruder 28, that is, on the supply side of the metering gear pump 29 is controlled to be constant as described above.
[0019]
Thus, since the supply-side rubber pressure of the supply-side metering pump 16 of the non-vulcanizable rubber composition with respect to the barrel 13 of the continuous kneader is controlled to be constant, the above-described rubber composition is not filled in the barrel 13. Kneading while feeding under atmospheric pressure. Therefore, notches 12a and segments 12b are formed in the screw blades 12 of the kneading screw 10, and shear pins 13a are provided on the inner surface of the barrel 13 to increase the kneading efficiency. In addition, the generation of heat associated with kneading can be suppressed. Therefore, the vulcanizable rubber composition is immediately sent from the continuous kneader to the screw extruder 28, and the physical properties of the vulcanizable rubber composition supplied to the screw extruder 28 are stabilized. Then, the above vulcanizable rubber composition is extruded from the die head 30 via the screw type extruder 28 and the metering gear pump 29, and at this time, the discharge side pressure of the screw type extruder 28 is controlled to be constant. The external accuracy of the product 33 is improved.
[0020]
In the above-described embodiment, the screw feeder 15 as the rubber supply device and the subsequent arrangement of the metering gear pump 16 are such that the non-vulcanizable rubber composition discharged from the metering gear pump 16 is smoothly supplied to the rubber supply port 13a of the barrel 13. As long as it is supplied, any of a vertical direction, a horizontal direction, and an inclination direction may be used. Further, the screw type extruder 28 may be arranged vertically, horizontally, or diagonally. Further, the screw type extruder 28 in the horizontal direction is positioned below the discharge end of the barrel 13 of the continuous kneader, and The vulcanizable rubber composition may be dropped from the discharge end.
[0021]
【The invention's effect】
As described above, the invention described in claim 1 can continuously perform final rubber kneading and extrusion by adding a vulcanizing agent and a vulcanization accelerator to a non-vulcanizable rubber composition. It is possible to suppress heat generation due to kneading, and even kneaded rubber for a short time can be easily kneaded in a short time without causing burning, and the vulcanizable rubber composition after kneading can be added to the composition over time. It is possible to extrude while no change occurs, an extrudate with good dimensional accuracy is obtained , and the shearing action applied to the rubber composition during kneading in the screw type continuous kneader is increased, and the kneading efficiency is improved. The time required for kneading is further shortened. In particular, according to the invention described in claim 2, the external accuracy of the extrusion-molded product is improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an embodiment.
FIG. 2 is a cross-sectional view of a kneading screw.
[Explanation of symbols]
10: Kneading screw of continuous kneader 11: Mandrel of continuous kneader 12: Screw blade 12a: Notch 12b: Segment 13: Barrel 13a: Rubber supply port 13b: Additive supply port 13c: Shear pin 14: Screw drive Device 15: Screw feeder 15A, 28A: Drive motor 16, 29: Metering gear pump 17: Rubber sheet 18: Supply roller 19: Carrier 20: Rubber supply pressure control device 21, 32: Pressure sensor 22: Hopper 23: Push screw 24: Cross-linking agent tanks 25 and 27: constant supply device 26: accelerator tank 28: screw type extruder 30: die head 31: discharge pressure control device 33: extrusion molded product

Claims (2)

A rubber supply port and an additive supply port are opened on the base side and the center of the barrel of the continuous kneader, respectively, and a rubber supply device for supplying a non-vulcanizable rubber composition is connected to the rubber supply port via a quantitative gear pump. , Connect the vulcanizing agent and vulcanization accelerator quantitative supply device to the additive supply port, and connect the die side for extrusion of vulcanizable rubber composition to the discharge side end of the barrel via an extruder or quantitative gear pump The pressure of the non-vulcanizable rubber composition sent from the rubber supply device to the metering gear pump is controlled to be constant, and the non-vulcanizable rubber composition, the vulcanizing agent and the vulcanization accelerator in the continuous kneader are increased. becomes as kneaded under pressure, the above continuous mixer is a screw type continuous kneader uniaxial, that comprises kneading screw and barrel respectively temperature control, kneading screw scan It consists of a feed screw section with continuous Liu blades and a kneading section segmented by cutting out the screw blades, and the feed screw portion is provided immediately below the rubber supply port and additive supply port. The kneading portion is provided in a portion excluding each of the rubber supply port and the additive supply port, and the kneading portion reciprocates a distance corresponding to one pitch in the axial direction while rotating in one direction in the barrel. A continuous kneading and extruding apparatus for rubber, characterized in that a shear pin protrudes from the inner surface of the barrel surrounding the screw and enters between the screw blades . The barrel screw extruder and quantitative gear pump on the discharge side end portion of the are connected in series, a rubber continuous kneading extruder apparatus of this quantitative gear pump according to claim 1, wherein extrusion die head is connected for.

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