JP2011201311A - Continuous kneader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous kneader which can improve kneading quality by enhancing shearing force while securing the capacity of extruding a material to be kneaded.SOLUTION: The invention relates to a twin-screw kneading extruder 1 equipped with a kneading rotor 7 which is incorporated in a screw set 3 inside a barrel 2 and applies shearing force to the material to be kneaded, in a clearance between the tips of blades on the outer face of the kneading rotor 7 and the inner wall face of a chamber to knead the material to be kneaded. The kneading rotor 7 is equipped with a long blade 12 twisted continuously in the direction of extrusion and one or more short blades 13a and 13b extending from the shaft end of the kneading rotor body, on the outer periphery of the kneading rotor body 11. The short blades 13a and 13b are made shorter than half of the length of the kneading rotor body 11. Kneading discs 15A and 15B of which the sectional shape changes in a discontinuous manner are placed on at least either upstream or downstream of the kneading rotor 7.

Description

  The present invention relates to a continuous kneading apparatus for kneading a target material (a material to be kneaded) while continuously extruding it with a single screw (single screw) or a twin screw kneading extruder in order to improve physical properties such as rubber and plastic.

  As a device for kneading a material to be kneaded such as rubber, a batch-type kneader is mainly known. For example, when rubber is kneaded, raw rubber and a compounding agent are charged into a batch-type kneader and kneaded. However, excessive heat generation due to the kneading action causes deterioration of rubber quality.

  Therefore, in the current kneading operation, the temperature of the material to be kneaded during kneading is monitored, and when the temperature rises to a predetermined temperature (for example, about 150 ° C. for rubber) before the material to be kneaded is deteriorated. The operation of discharging the material to be kneaded from the kneader, cooling the material to be kneaded, and charging it again into the kneader is repeated an appropriate number of times.

  This repeated kneading step is called a re-milling (re-milling) step, but since this step takes a lot of time, it becomes a factor of reducing the productivity of products such as tires. For this reason, there is a demand for a kneading apparatus having a small calorific value of the material to be kneaded while having good kneading performance and dispersion performance.

  On the other hand, the techniques described in Patent Document 1 and Patent Document 2 below are continuous uniaxial and biaxial kneading extruders and the like that can continuously knead materials to be kneaded such as resin and high-viscosity rubber. The present invention relates to a kneading apparatus.

  For example, a twin-screw kneading extruder is configured by combining one or a plurality of segments such as a kneading rotor, a kneading disk, and a screw on the outer periphery of two rotating shafts. It is an apparatus that conveys and kneads a material to be kneaded such as rubber or resin continuously supplied by rotating in the same direction or different directions in the chamber.

  When kneading rubber or the like using this twin-screw kneading extruder, first, a material to be kneaded made of a rubber composition to which rubber or various compounding agents are added is supplied to the feed section of the twin-screw kneading extruder. To do. In the feed section, the material to be kneaded is heated and extruded to the kneading section on the downstream side in the axial direction.

  Next, in the kneading part, a shearing force is applied by a kneading rotor or the like to knead. The kneading rotor includes a blade portion on the outer surface of the rotor body, and applies a strong shearing force to the material to be kneaded through a gap formed between the tip of the blade portion and the inner wall surface of the chamber, so-called chip clearance.

  Then, the kneaded material is carried out to the next process by the screws opposed to each other in the extruding unit located on the downstream side of the kneading unit.

Japanese Patent Application No. 2003-381887 Japanese Patent Application No. 2004-206826

  However, in the above-described continuous kneading apparatus, a high viscosity kneaded material such as rubber has a large heat generation due to shearing, and the cooling performance of the continuous kneading apparatus is insufficient, resulting in a high temperature, resulting in a decrease in kneading performance and deterioration of rubber quality. There was a fear.

  On the other hand, in order to prevent temperature rise, there is a problem that productivity is lowered when the number of rotations of the rotating shaft is reduced or rubber is once discharged and re-kneaded as in the batch kneader described above. is there. In addition, there is a drawback that the length of the apparatus is inevitably increased when trying to secure a residence time necessary for kneading while continuously extruding.

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a continuous kneading apparatus capable of improving the kneading quality by increasing the shearing property while ensuring the extrusion ability of the material to be kneaded.

The continuous kneading apparatus according to the present invention for solving the above problems is as follows.
A barrel with a cylindrical chamber;
A screw set that pushes the material to be kneaded downstream by rotating in the chamber, and a kneading that is incorporated in the screw set and that kneads the material to be kneaded by applying shear in the gap between the inner wall surface of the chamber. A rotor,
In a continuous kneading apparatus equipped with
The kneading rotor includes long blades continuously twisted in the extruding direction on the outer periphery of the rotor body and one or more short blades extending from the rotor body shaft end, and the length of the short blade is one of the length of the rotor body. A kneading disk having a cross-sectional shape that discontinuously changes is disposed at least one of upstream and downstream of the kneading rotor.

Also,
The kneading disk is characterized by having a neutral blade having no ability to extrude the material to be kneaded.

  According to the continuous kneading apparatus according to the present invention, the kneading rotor includes, on the outer periphery of the rotor body, long blades continuously twisted in the extrusion direction and one or more short blades extending from the rotor body shaft end. Since the length of the blade is shorter than 1/2 of the length of the rotor body, it is possible to improve the kneading quality by increasing the shearing property while ensuring the extrusion ability of the material to be kneaded, and at the upstream of the kneading rotor. Alternatively, a kneading disc with a discontinuously changing cross-sectional shape is disposed on at least one of the downstream sides, so that the function of the kneading rotor is fully exerted by the non-feeding action and returning action of the material to be kneaded by the kneading disk. Since the kneading performance in the section is further improved, the apparatus length can be shortened, and space saving and cost reduction can be achieved.

It is an expanded view of the kneading rotor which shows Example 1 of this invention. It is a graph which shows the relationship between a blade twist angle and an axial direction pressure gradient. It is a plane sectional view of a twin screw kneading extruder. It is an expanded view of the kneading rotor which shows Example 2 of this invention. It is an expanded view of the kneading rotor which shows Example 3 of this invention. It is a graph which shows the relationship between the rotor shaft / blade diameter ratio and rubber temperature (cooling performance) which show Example 4 of this invention. It is a plane sectional view of the twin-screw kneading extruder showing Example 5 of the present invention. It is a plane sectional view of the single screw kneading extruder showing Example 6 of the present invention. It is the graph which compared the dispersion degree improvement effect of a prior art and this invention.

  Hereinafter, the continuous kneading apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a development view of a kneading rotor showing Example 1 of the present invention, FIG. 2 is a graph showing the relationship between blade twist angle and axial pressure gradient, and FIG. 3 is a plan sectional view of a twin-screw kneading extruder.

  As shown in FIG. 3, the twin-screw kneading extruder 1 has a pair of screw sets 3 parallel to the inside of the barrel 2. The screw set 3 includes an extruding portion 6 (one end portion) provided with a screw (fin) 5 on the outer surface of the rotating shaft 4 from the supply side of the material to be kneaded such as rubber or a rubber-based composition, and the rotating shaft 4. A kneading part 8 (intermediate part) provided with a plurality of (4 in the illustrated example) kneading rotors 7 on the outer surface, and an extruding part 10 (other end part) provided with screws (fins) 9 on the outer surface of the rotary shaft 4 ).

  Therefore, in the twin-screw kneading extruder 1, the opposing screws 5 of the extruding unit 6 convey the material to be kneaded introduced from a hopper (not shown) in the downstream direction and supply it to the kneading unit 8. In the kneading section 8, a shearing force generated by the meshing of the plurality of kneading rotors 7 provided on the outer surface of the rotating shaft 4 and between the blade tip of the kneading rotor 7 and the inner wall surface of the barrel 2. The material to be kneaded is kneaded. Then, the kneaded material is carried out to the next step by the screw 9 facing each other in the extrusion unit 10 located on the downstream side of the kneading unit 8.

  As shown in FIG. 1, the kneading rotor 7 has two long blades 12 continuously twisted in the extrusion direction on the outer periphery of the rotor body 11 and two (one piece) extending from the upstream and downstream sides in the extrusion direction of the rotor body shaft end. (Or three or more blades 13a and 13b), and the lengths La and Lb of the short blades 13a and 13b are shorter than ½ of the length L of the rotor body.

  The twist angle θL of the long blade 12 with respect to the rotor body axis is set to 30 to 60 °, and the twist angle θS of the short blade (first short blade) 13a on the upstream side in the extrusion direction with respect to the rotor body axis is also set to 30 to 60. It is set to °. Note that the twist angle of the short blade (second short blade) 13b on the downstream side in the extrusion direction may be set to 30 to 60 °.

  Since it is configured in this manner, in the kneading unit 8 in the twin-screw kneading extruder 1, the pair of opposed rotor bodies 11 are arranged with a phase difference of 180 ° from each other. The long blade 12 of the rotor main body 11 passes between the short blade 13a and the short blade 13b of the other rotor main body 11 while meshing with them.

  Thereby, it is possible to improve the kneading quality by increasing the shearing property while ensuring the extrusion capability of the material to be kneaded.

  In the present embodiment, the twist angle θL of the long blade 12 in the kneading rotor 7 with respect to the rotor body axis is set to 30 to 60 °, and the rotor body axis of the short blade (first short blade) 13a on the upstream side in the extrusion direction. Since the twist angle θS with respect to is also set to 30 to 60 °, the temperature rise of the material to be kneaded is suppressed. Hereinafter, the reason will be described with reference to the graph of FIG.

  As is apparent from the graph of FIG. 3, the maximum pressure gradient is obtained when the blade twist angles θL and θS are 45 °. At this time, the axial flow of the material to be kneaded is the best, and the mixing and dispersion of the compounding agents are performed. The property is also the best. When the blade twist angles θL and θS are 30 to 60 °, good axial fluidity is ensured while maintaining the necessary shearing force. If such good axial fluidity is ensured, the temperature rise of the material to be kneaded will be suppressed.

  In the above embodiment, one or more kneading rotors 7 may be arranged intermittently at a plurality of locations on the screw set 4.

  FIG. 4 is a development view of the kneading rotor showing Example 2 of the present invention.

  This is because, in the kneading rotor 7 in the first embodiment, the rotor body shaft end side of the long blade 12A is notched, and the length La of the short blades 13a and 13b is longer than the axial length Lc and Ld of the long blade notch. This is an example in which Lb is lengthened. Since the other configuration is the same as that of the first embodiment, the same members as those in FIG.

  According to this, in addition to the same operations and effects as in Example 1, the flow of the material to be kneaded is branched at the long blade notch, thereby further improving the axial fluidity at the long blade 12A. There is an advantage that.

  FIG. 5 is a development view of the kneading rotor showing the third embodiment of the present invention.

  This is an example in which the twist angle of the short blade 13b on the downstream side in the extrusion direction is reversed in the kneading rotor 7 in Examples 1 and 2, that is, the angle of the short blade 13b is expanded outward toward the upstream side in the extrusion direction. is there. Since the other configuration is the same as that of the first embodiment, the same members as those in FIG.

  According to this, in addition to the same operations and effects as in Example 1, the kneading residence time is increased by the short blade 13b that is inverted while extruding the material to be kneaded in the kneading rotor 7, and the kneading quality is further improved. There is an advantage that it can be planned.

  FIG. 6 is a graph showing the relationship between the rotor shaft / blade diameter ratio and the rubber temperature (cooling performance) in Example 4 of the present invention.

  This is because, in the kneading rotor 7 in Examples 1 to 3 (see FIGS. 1, 4 and 5), D1 / D2, which is the ratio of the rotor body outer diameter (rotor shaft) D1 to the blade diameter D2, is 0.35. As described above, the example is preferably set to 0.5 or more, and the other configurations are the same as those in the first to third embodiments. Therefore, the same members as those in FIGS. Is omitted.

  According to this, in addition to the same operations and effects as in Examples 1 to 3, there is an advantage that the cooling performance (heat transfer capability) in the kneading rotor 7 is further improved.

  That is, by setting D1 / D2, the thickness of the material to be kneaded between the kneading rotor 7 and the barrel 2 (see FIG. 3) can be optimized from the viewpoint of heat transfer capability, and the cooling mechanism using cooling water inside the barrel 2 Since the cooling performance of the kneading part 8 (see FIG. 3) is enhanced and the cooling performance of the kneading part 8 (see FIG. 3) is enhanced, the cooling time (retention time of the material to be kneaded) is short as can be seen from the experimental results shown in FIG. However, the effect of lowering the temperature can be expected, and a highly versatile twin-screw kneading extruder 1 (see FIG. 3) that is not affected by the material of the material to be kneaded can be provided.

  FIG. 7 is a plan sectional view of a twin-screw kneading extruder showing Example 5 of the present invention.

  This is because the kneading rotors 7 in the first to fourth embodiments (one in the illustrated example, but a plurality of kneading rotors may be connected as shown in FIG. 3) on the upstream side and the downstream side (either one may be used). This is an example in which the ding disks 15A and 15B are arranged, and other configurations are the same as those in the first to fourth embodiments. Therefore, the same members as those in FIG.

  As the kneading disks 15A and 15B, those having a discontinuous change in cross-sectional shape and those having a neutral blade having no ability to extrude the material to be kneaded are selected.

  According to this, the function of the kneading rotor 7 is fully exhibited by the non-feeding action and the returning action of the material to be kneaded by the kneading disks 15A and 15B in addition to the actions and effects similar to those of the first to fourth embodiments. Since the kneading performance in the section 8 is further improved, there is an advantage that the apparatus length can be shortened, and space saving and cost reduction can be achieved.

  In the above embodiment, the combination of the kneading rotor 7 and the kneading disks 15A and 15B may be installed on the screw set 4 continuously or intermittently at a plurality of locations.

  FIG. 8 is a plan sectional view of a single-screw kneading extruder showing Example 6 of the present invention.

  This is an example in which the kneading rotor 7 in Examples 1 to 4 is applied to a single-screw kneading extruder, and the other components are the same as those in Examples 1 to 4. Therefore, the same members as those in FIG. A duplicate description is omitted. This also provides the same operation and effect as a twin-screw kneading extruder.

  FIG. 9 is a graph comparing the dispersion improvement effect of the prior art and the present invention.

  In the figure, (1) shows the case of a conventional screw only, (2) shows the case where a kneading disk is arranged in the middle of the conventional screw, and (3) shows the case where the kneading rotor of the present invention is arranged in the middle of the screw. (4) is the case where the kneading rotor of the present invention is disposed in the middle of the screw and the kneading disk of the present invention is disposed upstream thereof, and (5) is the kneading rotor of the present invention disposed in the middle of the screw. When the kneading disk of the present invention is arranged on the downstream side, the kneading rotor of the present invention is arranged in the middle of the screw, and the kneading disk of the present invention is arranged on the upstream side and downstream side of the kneading rotor. This is the case.

  This graph also shows that the present invention has a higher degree of dispersion improvement than the prior art.

  The continuous kneading apparatus according to the present invention can be applied not only to a material to be kneaded made of rubber or rubber to which various compounding agents are added, but also to a material to be kneaded made of resin or the like.

  DESCRIPTION OF SYMBOLS 1 Twin screw kneading extruder, 2 barrel, 3 screw set, 4 rotary shaft, 5 screw, 6 extrusion part, 7 kneading rotor, 8 kneading part, 9 screw, 10 extrusion part, 11 rotor main body, 12 long blade, 13a, 13b Short blade, 15A, 15B Kneading disc, 20 Uniaxial kneading extruder, θL long blade twist angle, θS short blade twist angle, La, Lb Short blade length, Lc, Ld Long blade notch length D1 rotor outer diameter, D2 blade diameter.

Claims (2)

A barrel with a cylindrical chamber;
A screw set that pushes the material to be kneaded downstream by rotating in the chamber, and a kneading that is incorporated in the screw set and that kneads the material to be kneaded by applying shear in the gap between the inner wall surface of the chamber. A rotor,
In a continuous kneading apparatus equipped with
The kneading rotor includes long blades continuously twisted in the extruding direction on the outer periphery of the rotor body and one or more short blades extending from the rotor body shaft end, and the length of the short blade is one of the length of the rotor body. A continuous kneading apparatus characterized in that a kneading disk having a cross-sectional shape discontinuously changing is disposed at least one of upstream and downstream of the kneading rotor while being shorter than / 2.   2. The continuous kneading apparatus according to claim 1, wherein the kneading disk has a neutral blade having no ability to extrude the material to be kneaded.

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