JP2013086017A - Mixer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mixer with high mixing performance by which uniform mixing can be performed without leaving secondary particle aggregate even by operation for a short time.SOLUTION: The mixer 1 is provided with a cylindrical container 2 for accommodating powder, and a high speed rotor 3 which is constituted by projecting a bar-shaped impulse member 32 from a shaft body 31 rotating in the container 2. Circumferential velocity of an end part 32a of the impulse member 32 is 80 m/s or more, the container 2 is arranged so that a central axis thereof so as to be horizontal and a rotary shaft of the high speed rotor 3 is in parallel to the central axis of the container. Further the mixer is provided with a low speed rotor 4 rotating around the central axis of the container 2 and a stirring member 42 for stirring the powder is provided at an outer circumference of the low speed rotor 4 close to an inner wall 2a of the container 2.

Description

  The present invention relates to a mixer used for mixing various powders.

  As a conventional mixer, in a horizontally placed cylindrical container, a bowl-shaped low speed rotor equipped with a stirring member that rotates concentrically with the central axis of the container and stirs the powder in the container, and this low speed There is known a mixer provided with a high-speed rotor that is disposed inside a rotor and provided with a plurality of impact members on the outer periphery (see Patent Document 1).

  The low-speed rotor and high-speed rotor of this mixer operate as follows. That is, the low-speed rotor stirs the powder in the container, lifts the powder lump upward, and then drops it downward toward the high-speed rotor. When the impact member of the high-speed rotor collides with the falling powder lump at high speed, the lump of powder is crushed and falls below the container. The fallen powder is lifted upward again by the low-speed rotor. By repeating this process, the powder is mixed.

  As described above, the conventional mixer is configured to efficiently and uniformly mix. However, it is known that in the case of a powder having a small particle diameter such as carbon black, an aggregate of secondary particles such as a structure structure is likely to be generated, and homogeneous mixing is difficult. When mixing using a conventional mixer, there has been a problem that even if it is operated for a long time, aggregates of secondary particles remain and are not uniformly mixed.

Japanese Patent Publication No. 60-551754

  Therefore, there has been a demand for a mixer having high mixing performance in which agglomerates of secondary particles do not remain even in a short time operation and can be mixed uniformly.

  Incidentally, the rotational speed of the high-speed rotor of the conventional mixer is, for example, 6500 rpm in the mixer according to Patent Document 1, but according to the study of the present inventor, mixing proceeds to some extent at the rotational speed of the conventional mixer. After that, it became clear that it took a very long operation time to mix more homogeneously.

  Therefore, the problem to be solved by the present invention is to provide a mixer having a high mixing performance in which agglomerates of secondary particles do not remain even in a short time operation and mixing is performed homogeneously.

  The present invention has been made to solve the above problems, and the invention according to claim 1 includes a cylindrical container for storing powder, and a rod-shaped impact member from a shaft rotating in the container. And a projecting high-speed rotor, wherein the impact member has a peripheral speed of 80 m / s or more.

  According to the first aspect of the present invention, it is possible to provide a mixer having high mixing performance capable of homogeneously mixing in a short time even a powder having a small particle diameter that forms an aggregate of secondary particles. .

  According to a second aspect of the present invention, the container is arranged so that the central axis of the container is horizontal, the rotation axis of the high-speed rotor is parallel to the central axis of the container, and the central axis of the container is the center. The mixer according to claim 1, further comprising a rotating low-speed rotor, wherein an agitating member for agitating the powder in the vicinity of the inner wall of the container is provided on an outer periphery of the low-speed rotor. .

  According to the second aspect of the present invention, since the powder is stirred by the low speed rotor in the container, the number of times the powder collides with the impact member of the high speed rotor is increased. It is possible to provide a mixer with high mixing performance.

  ADVANTAGE OF THE INVENTION According to this invention, the mixer with high mixing performance which can mix uniformly about powder with a small particle diameter which forms an aggregate in a secondary particle in a short time can be provided.

It is a front view which shows the mixer which concerns on this invention. It is a cross-sectional front view for showing the inside of the container periphery of the mixer which concerns on this invention. It is the photograph which expanded 50,000 times the carbon black used by an Example and a comparative example. It is an Example which shows the case where the mixer which concerns on this invention is drive | operated for 1 minute, and mixes calcium carbonate and carbon black, (a) is a photograph expanded 20,000 times, (b) is 50,000 times. This is an enlarged photo. It is a comparative example which shows the case where a conventional mixer is operated for 1 minute to mix calcium carbonate and carbon black, (a) is a photograph magnified 20,000 times, and (b) is magnified 50,000 times. It is a photograph. It is a comparative example which shows the case where a conventional mixer is operated for 5 minutes to mix calcium carbonate and carbon black, (a) is a photograph magnified 20,000 times, and (b) is magnified 50,000 times. It is a photograph.

  Next, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is particularly limited in the following description. As long as there is no description of the effect, it is not restricted to these aspects.

  FIG. 1 is a front view showing a mixer according to the present invention, and FIG. 2 is a cross-sectional front view for showing the inside of the periphery of a container of the mixer according to the present invention. The mixer 1 according to the present invention includes a cylindrical container 2 that stores powder, a high-speed rotor 3 that rotates in the container 2, and a low-speed rotor 4 that rotates in the container 2 as main components. Although the shape and arrangement of these main components will be described below, they are generally the same as the conventional mixer described in Patent Document 1.

  The cylindrical container 2 is arranged with its central axis horizontal, and an inlet 5 for feeding powder and an outlet 6 for discharging powder communicate with the inside of the container 2.

  A high speed rotor 3 is provided inside the container 2, and the rotation axis of the high speed rotor 3 coincides with the central axis of the container 2. The high-speed rotor 3 includes a columnar shaft body 31 that extends along the rotation axis, and a plurality of rod-shaped impact members 32 that project radially from the surface of the shaft body 31. The shape of the rod-shaped impact member 32 is arbitrary, but it can be formed like a knife edge having a wedge-shaped cross section.

  The high-speed rotor 3 is freely supported by a known bearing or the like, and the shaft body 31 is driven by a driving means (not shown) to rotate the high-speed rotor 3 as a whole. Move with. The peripheral speed of the end portion 32a of the impact member 32 in the mixer 1 according to the present invention is 80 m / s or more.

  Although the rotation axis of the high-speed rotor 3 shown in the figure coincides with the center axis of the container 2, it can be a rotation axis offset in parallel from the center axis. It is also possible to provide a plurality of high speed rotors 3.

  A low speed rotor 4 is provided inside the container 2, and the rotation axis of the low speed rotor 4 coincides with the central axis of the container 2. The low-speed rotor 4 includes an arm 41 that extends radially in the radial direction of the cylinder of the container 2, and a stirring member 42 that is connected to the arm 41 and extends parallel to the central axis while being close to the inner wall 2 a of the container 2. .

  The low-speed rotor 4 is rotatably supported by a known bearing or the like, and is driven by the driving means 7. The drive means 7 is appropriately configured from a motor, a speed reducer, and other known elements. The low-speed rotor 4 is rotationally driven by the driving means 7, and accordingly, the agitating member 42 also rotates while being separated from the inner wall 2 a of the container 2 by a predetermined distance, and agitates the powder in the container 2.

  The stirring member 42 can be a linear member that extends parallel to the central axis of the container 2 as described above, but is a spiral member that extends along the inner wall 2a of the container 2. Is also possible. In addition, a scraper that contacts the inner wall 2a of the container 2 can be connected to the stirring member 42, whereby the bulky powder that is in close contact with the inner wall 2a of the container 2 can be peeled off.

  Next, powder mixing using the mixer 1 according to the present invention will be described.

  The powder to be mixed is charged from the charging port 5 and stored in the container 2. As the low-speed rotor 4 rotates, the stirring member 42 stirs the powder in the container 2. In particular, the powder in the vicinity of the inner wall 2 a is once lifted upward by the stirring member 42 that rotates while being separated from the inner wall 2 a by a predetermined distance, and then falls toward the high-speed rotor 3. The dropped powder collides with the impact member 32 of the high speed rotor 3. At this time, the end portion 32a of the impact member 32 moves at a high speed of a peripheral speed of 80 m / s or more, so that the aggregates of the secondary particles are also crushed and the mixing of the powder proceeds. After a predetermined time has elapsed, the rotation of the low speed rotor 4 and the high speed rotor 3 is stopped, and the powder is discharged from the discharge port 6. The operation time is appropriately adjusted according to the type of powder and the required degree of mixing.

  Next, an example in which powder is mixed using the mixer according to the present invention and a comparative example in which powder is mixed using a conventional mixer will be compared. The powder to be mixed is calcium carbonate # 1500 (average particle diameter 2.5 μm) and carbon black (primary particle diameter 0.03 μm), and the mixing ratio is calcium carbonate: carbon black = 95: 5 by mass ratio. . FIG. 3 shows an enlarged photograph of 50,000 times the carbon black used in the examples and comparative examples. As shown in FIG. 3, it can be seen that carbon black has a small particle size and thus forms a structure structure that is an aggregate of secondary particles.

  The mixer according to the present invention used in the examples and the conventional mixer used in the comparative example are common in the shape and arrangement of the components, and the diameter of the cylindrical container is 100 mm, and the central axis direction is The length is 65 mm. The diameter of the high speed rotor is 59 mm, the diameter of the low speed rotor is 98 mm, and the rotation speed is 350 rpm. On the other hand, the difference between the mixer according to the present invention used in the examples and the conventional mixer used in the comparative example is the rotational speed of the high-speed rotor.

(Example)
The rotation speed of the high-speed rotor of the mixer according to the present invention used in the examples is 27000 rpm. Therefore, the peripheral speed at the end of the impact member is 83.4 m / s.

  FIG. 4 shows a photograph of the powder mixed by operating the mixer according to the above example for 1 minute. FIG. 4A is a photograph magnified 20,000 times, and FIG. 4B is a photograph magnified 50,000 times. As is apparent from these two photographs, the structure of carbon black is almost eliminated, and it can be seen that the secondary particle diameter of the slightly remaining structure is extremely smaller than the particle diameter of calcium carbonate. That is, it can be seen that homogeneous mixing is realized.

(Comparative example)
The rotational speed of the high-speed rotor of the conventional mixer used for the comparative example is 9700 rpm. Therefore, the peripheral speed at the end of the impact member is 30.0 m / s.

  The photograph of the powder which mixed the mixer which concerns on said comparative example by operating for 1 minute same as an Example is shown in FIG. FIG. 5A is a photograph magnified 20,000 times, and FIG. 5B is a photograph magnified 50,000 times. As is clear from these two photographs, the structure of carbon black has not been eliminated, the presence of secondary agglomerates comparable to the particle size of calcium carbonate is observed, and mixing has not progressed. I understand.

  Next, FIG. 6 shows a photograph of powder mixed by operating the mixer according to the comparative example for 5 minutes. FIG. 6A is a photograph magnified 20,000 times, and FIG. 6B is a photograph magnified 50,000 times. When FIG. 6 is compared with FIG. 5, it can be seen that the structure is not solved yet, although the mixing is advanced in the case of operating for 5 minutes than in the case of operating for 1 minute. That is, in Comparative Example 2, it is not possible to realize the homogeneous mixing as in the example even though the rotation speed is about one third of that in the example and the operation is five times as long as the example. Recognize.

  From the results of Examples and Comparative Examples, it became clear that homogeneous mixing, which required a long time operation in the conventional mixer, can be realized in a short time by the mixer according to the present invention. If the peripheral speed of the end portion of the impact member of the mixer is 80 m / s or more, homogeneous mixing can be realized in a short time.

1 Mixer 2 Container 2a Inner Wall 3 High Speed Rotor 32 Impact Member 32a End 4 Low Speed Rotor 42 Stirring Member

Claims (2)

A cylindrical container containing powder;
A high-speed rotor in which a rod-shaped impact member protrudes from a shaft that rotates in the container;
The mixer characterized by the peripheral speed of the edge part of the said impact member being 80 m / s or more. The container is arranged so that the central axis of the container is horizontal,
The rotational axis of the high-speed rotor is parallel to the central axis of the container;
A low-speed rotor that rotates about the central axis of the container;
The mixer according to claim 1, wherein a stirring member that stirs the powder in the vicinity of the inner wall of the container is provided on an outer periphery of the low-speed rotor.