JP2007260486A - Dispersing machine and manufacturing method of paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dispersing machine which is few in amount of foreign matter, ensures excellent dispersion and causes no damage of parts. <P>SOLUTION: The dispersing machine is constituted so that in a cylindrical vessel which is provided with a supply port of mill base located near one side end part in the center axis direction and an outlet port of the mill base located near the other side end part, and has a circular cross-sectional shape of the inner surface in the direction vertical to the center axis, a rotatable rotor where a plurality of grooves parallel with the center axis are formed on the outer circumferential part of the rotor and a plurality of rollers which are arranged rotatably and revolvably in the grooves, are included, wherein a roller having a tapered shape in which a cross-section vertical to the longitudinal direction is circular, and the diameter D of the cross-section in a central part and the diameter r of the top end part on the mill base supply port side satisfy the following relation (1) is used for one part of the plurality of rollers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a disperser suitable for finely dispersing a high-viscosity material (hereinafter referred to as a mill base) such as a paint, printing ink, paste, or magnetic paint.

  Roll mills and sand mills are widely used as dispersers for finely dispersing high-viscosity mill bases, but roll mills are open-type equipment, so the work environment deteriorates due to the evaporation of the solvent, and foreign substances from the work environment are removed. There is a problem of mixing, and there are many losses. Also, skill is required for machine operation, and there is a problem of poor dispersion due to non-uniformity of the gap between the rolls. On the other hand, the sand mill can have a sealed structure and can be continuously processed. However, the replacement frequency due to wear and destruction of the grinding media is high, and in a high-viscosity mill base, the media is placed on the screen or gap separator arranged at the outlet. There was also a problem of being unable to concentrate and drive.

  As an alternative to these, a disperser using a roller has been proposed (see, for example, Patent Document 1). A rotating shaft arranged coaxially with the cylindrical container supports a roller so that it can move radially outward and rotate, and this roller is pressed against the inner wall surface of the container by centrifugal force to rotate while rotating. Dispersion is performed by revolving inside the container. However, since the mill base passing part is very large, the mill base passes through untreated than the amount supplemented and dispersed in the dispersion region of the inner wall of the container by revolving the roller while the roller rotates. However, there is a problem of a short path that passes through without being sufficiently processed.

  In addition to this, as a disperser using an annular roller, there is a disperser using a tapered roller bearing (see, for example, Patent Document 2). A plurality of tapered roller bearings are arranged in a cylindrical container, and dispersion is performed by pressing on the rolling surface by rolling of the bearing roller. However, in this case as well, the fluidity of the mill base does not increase relative to the apparent rotational speed, and as a result, there arises a short path problem that the mill base passes through without being sufficiently processed. Further, a retainer for holding the bearing roller is necessary, and the presence of this retainer significantly impedes the flow of the mill base and prevents the mill base from being made uniform. Furthermore, even if the bearings are mounted in close contact with the rotating shaft, a gap is always generated between adjacent bearing rollers, so that not only the mounting efficiency is poor, but also the mill base is not dispersed between the bearing rollers. Thus, it is clear that at least the mill base passes through without being sufficiently processed, so-called short path problem occurs, and the function as a continuous processing disperser is not sufficiently performed.

Furthermore, as a continuous processing disperser, a disperser having a rotor and a roller capable of revolving is proposed (for example, Patent Document 3 and Patent Document 4). The disperser has a rotatable rotor in which a plurality of grooves parallel to the rotation axis are formed coaxially with the cylindrical container, and has a roller that can rotate and revolve in the grooves, and the rotor rotates. The mill base performs dispersion by compressing and shearing between the roller and the inner wall of the cylindrical container, and between the roller and the groove inner surface of the rotor. Here, the passage part of the mill base is a gap part between the inner wall surface of the cylindrical container and the outer peripheral surface of the rotor, and a slight gap between the groove and the roller formed in the rotor. However, when a high-viscosity mill base having a viscosity of several tens of Pa · s or more is dispersed, the mill base is less likely to penetrate into the gap between the groove formed on the rotor and the roller, and rotation of the roller may be prevented. is there. In addition, when sufficient mixing is not performed in the preliminary mixing, the aggregate of particles contained in the mill base may be caught in the gap between the groove and the roller, thereby preventing the roller from rotating. When the rotation of the roller is thus prevented, the mill base cannot sufficiently receive the shearing action by the roller, and there arises a problem of a short path that passes through without being finely dispersed. In addition, if the rotation of the rotor is continued without the roller rotating, there may be a problem of foreign matter entering the mill base due to scraping or chipping of the roller, rotor, and cylindrical container, or a problem that may result in inoperability due to component damage. is there.
JP-A-5-096197 Japanese Patent Publication No.53-003110 JP-A-11-197479 JP 2004-905 A

  The present invention eliminates the so-called short pass problem that the mill base passes through without being sufficiently treated, and can perform sufficient dispersion even in a high viscosity mill base having a viscosity of several tens of Pa · s or more. It is an object of the present invention to provide a continuous processing disperser that is free from damage caused by chipping or chipping of parts.

In order to achieve the above object, the present invention is a disperser having the following configuration. That is, a cylindrical container having a mill base supply port in the vicinity of one end portion in the central axis direction and a mill base discharge port in the vicinity of the other end portion, and having a circular cross section on the inner surface in the direction perpendicular to the central axis A disperser having a rotatable rotor in which a plurality of grooves parallel to the central axis are formed in an outer peripheral portion, and having a plurality of rollers arranged to rotate and revolve in the grooves, In some of the plurality of rollers, the cross section perpendicular to the longitudinal direction is a circle, and the diameter R of the cross section in the central portion and the diameter r of the tip end on the mill base supply port side satisfy the relationship of the following formula (1) A disperser using a roller having a shape.
r / R <0.8 (1)

  When the disperser of the present invention is used, even a high-viscosity mill base is uniformly dispersed without causing a short pass, and there is an effect that it is possible to produce a mill base that does not damage parts and does not contain foreign matter.

  The most preferred embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing an example of a disperser according to the present invention, and FIG. 2 is a vertical cross-sectional view showing an example of a disperser according to the present invention. FIG. 3 is an enlarged cross-sectional view showing the vicinity of the roller of FIG.

  The disperser of the present invention includes a mill base supply port 9 in the vicinity of one end portion in the central axis direction, and a mill base discharge port 10 in the vicinity of the other end portion, and a cross-sectional shape of the inner surface in a direction perpendicular to the central axis. Has a cylindrical container 1 which is a circle. Since the rotor 2 and the roller 5 described later rotate inside the cylindrical container and the distance between the rotor 2 and the roller 5 and the inner surface of the cylindrical container 1 is kept constant, the cross-sectional shape of the inner surface in the direction perpendicular to the central axis is a circle. There must be. If the cross-sectional shape of the inner surface is not a circle, a sufficient dispersion effect cannot be obtained. The inner shape of the cylindrical container may be a cylinder, or may be a tapered shape such that the cross section of the inner surface becomes smaller near the supply port 9 or the discharge port 10 of the mill base at both ends.

  Further, the cylindrical container of the present invention includes a mill base supply port 9 near one end in the central axis direction, and a mill base discharge port 10 near the other end. As a result, the mill base introduced into the cylindrical container 1 from the supply port 9 is subjected to a dispersion process along the inner surface of the cylindrical container 1 until reaching the discharge port, and a sufficient dispersion effect can be obtained.

A rotor 2 that can rotate coaxially with the cylindrical container 1 is disposed in the cylindrical container 1. A plurality of grooves 4 parallel to the rotation shaft 3 are formed on the outer periphery of the rotor 2, and a roller 5 is disposed in each groove 4.
When the rotor 2 rotates in the cylindrical container 1, the roller 5 enclosed in each groove 4 of the rotor 2 is brought into contact with the inner wall surface of the cylindrical container 1 by centrifugal force and rotates in the cylindrical container 1. Revolve. And the mill base forcedly introduced into the cylindrical container 1 from the supply port 9 is pressed against the inner wall surface of the cylindrical container 1 by the roller 5 in the gap 7 and, as shown in FIG. A slight gap 6 formed between the inner wall of the groove 4 and the outer peripheral surface of the roller 5 is pushed out to the discharge port 10 while being repeatedly subjected to compression and shearing action, and discharged from the discharge port 10.

  In the present invention, since the roller 5 is inserted into the groove 4 of the rotor 2, the rotational speed of the rotor 2 becomes the revolution speed of the roller 5. When the roller 5 revolves, the mill base is strongly pressed against the inner wall surface of the cylindrical container 1 by each roller 5, and repeatedly receives compression and shearing action.

  Further, as shown in FIG. 3, a slight gap 6 is formed between the inner wall of the groove 4 and the outer peripheral surface of the roller 5 by centrifugal force, and the mill base forcedly fed from the supply port 9 becomes the inner wall of the groove 4 and the roller. The roller 5 can revolve while rotating by the lubricating action by penetrating the entire gap 6 with the outer peripheral surface of the roller 5. As a result, the mill base is subjected to a strong compressing action and a shearing action by the roller 5 rotating in the groove 4 in the gap 7 and the slight gap 6 described above.

  As described above, in the present invention, the mill base can be uniformly distributed without being subjected to the compression, shearing, and rubbing actions at all locations in the cylindrical container 1 and causing short paths. .

  The size of the roller 5 is preferably set to a diameter that substantially contacts the inner wall surface of the cylindrical container 1 while being substantially inscribed in the groove 4, and there is a slight gap 6 formed between the groove 4 and the roller 5. More preferably, the diameter is 0.5 to 1.5 mm.

  One roller 5 may be arranged for each groove 4, but as shown in FIG. 1, it is advantageous from the viewpoint of maintenance that a plurality of rollers 5 are arranged in the central axis direction. In that case, the length of the roller 5 is preferably 15 to 100 mm. On the other hand, a plurality of grooves 4 may be formed with respect to the rotor 2, but a large number, preferably 8 or more, are formed radially as shown in FIG. Further, the cross-sectional shape of the groove 4 may be substantially C-shaped (arc) as shown in FIG. 3, but may be substantially U-shaped (shape where the bottom is an arc and the side is a straight line).

In the present invention, as the roller 5, at least a part of the plurality of rollers 5 has a circular cross section perpendicular to the longitudinal direction, and the cross-sectional diameter R at the center and the diameter r of the tip on the mill base supply port 9 side are A roller having a tapered shape satisfying the relationship of the following formula (1) is used.
r / R <0.8 (1)
By using the roller having the above tapered shape, the mill base can sufficiently easily penetrate into the slight gap 6 even when the high viscosity mill base is used as compared with the case where only the cylindrical roller is used. In addition, even when sufficient mixing is not performed in the preliminary mixing, the aggregate of particles contained in the mill base is gradually dispersed at the tapered portion, and the rotation of the roller is hindered due to the biting of the aggregate. The mill base easily penetrates into the slight gap 6. As the mill base penetrates into the small gap 6 in this way, the roller rotates smoothly due to its lubricating effect, and the mill base can receive a sufficient compressing action and shearing action, thereby causing a short path problem. It becomes difficult to do.

  It is preferable that the roller having a tapered shape has a shape including a cylindrical portion having a constant diameter and a tapered portion having a smaller diameter than the cylindrical portion. The length l of the tapered portion is preferably 3.5 to 15 mm. However, if the diameter of the cross section of the tapered portion is too thin, the strength of the roller is reduced, and the roller is easily broken. Therefore, it is preferable that the portion where the diameter of the cross section of the taper portion is 0.5 times or less of the diameter R of the cross section in the roller central portion is within 5 mm. The shape of the tapered portion may be any shape as long as the cross section in the direction perpendicular to the central axis is a circle, but it has a truncated cone shape as shown in FIG. 4, as shown in FIG. It is preferable that the shape be a part of a simple sphere or a part of a spheroid as shown in FIG.

  When the shape of the tapered portion is a truncated cone shape, the ratio of the cross-sectional diameter r at the tip portion to the cross-sectional diameter R at the roller central portion is preferably 0.3 to 0.8 times. Moreover, it is preferable that angle (theta) of a taper part shall be 5-45 degree | times.

  When the shape of the tapered portion is a part of a sphere, the radius of curvature of the spherical surface is preferably in the range of 1.0 to 2.0 times the radius of the cylindrical portion, but is 1.0 times, that is, the shape of the tapered portion. Is most preferably hemispherical.

  When the shape of the tapered portion is a part of the spheroid, the central axis of the cylindrical portion and the tapered portion are the same, the minor axis of the spheroid is 1.0 to 2.0 times the radius of the cylindrical portion, and the major axis Is preferably larger than 1.0 times the minor axis and not larger than 2.0 times. The roller having a tapered shape of the present invention may have a shape having tapered portions on both sides of the cylindrical portion, but in order to increase the dispersion performance, it is preferable that the roller has a tapered portion only on one side of the cylindrical portion. . In the case of a shape having a tapered portion only on one side of the cylindrical portion, the tapered portion is disposed so as to face the supply port 9 side of the mill base.

  In the disperser of the present invention, a roller having a tapered shape can be used for only a part of the rollers, and in the plurality of rollers, at least the roller closest to the end on the mill base supply port side of the rotor, A roller that is partially covered at least in a circumferential region including the roller of the rotor has the tapered shape, or the end of the groove on the mill base supply port side is: It is preferable that the rollers are substantially aligned so as to be aligned with a surface perpendicular to the central axis, and at least the roller closest to the mill base supply port of the groove has the tapered shape. It is more preferable to use more than half of all the rollers having a tapered shape, and it is most preferable that the total number of rollers be a roller having a tapered shape.

  It is preferable that a plurality of rollers having a tapered shape are arranged in the central axis direction with respect to one groove 4. When a plurality of rollers having a tapered shape are inserted in the width direction of the rotor 2 with respect to one groove, the entire inner wall surface in the cylindrical container 1 can be used as a dispersion region. Then, each tapered roller inserted in one groove 4 rotates independently, so that the mill base is independently compressed over the entire inner wall surface of the cylindrical container 1 by each tapered roller. , Subjected to shearing and rubbing action. As a result, a more uniformly dispersed mill base can be obtained. In the disperser of the present invention, it is preferable to form a jacket 8 through which cooling water, hot water, or warm water passes on the outer periphery of the cylindrical container 1. When the jacket 8 is formed, cooling water, hot water, or hot water passes through the jacket 8 so that the mill base can be cooled or dispersed while being heated.

  In the disperser of the present invention, in order to improve wear resistance, the cylindrical container 1, the rotor 2, and the roller 5 are preferably made of a cemented carbide material, a ceramic material such as zirconia or sialon.

  The mill base is preferably supplied using a metering pump 11 as shown in FIG. Specific examples of the metering pump 11 include centrifugal pumps such as centrifugal pumps and turbine pumps, propeller pumps such as axial pumps, viscous pumps such as vortex pumps, reciprocating pumps such as piston pumps, diaphragm pumps, and tube pumps, gear pumps, Examples of the rotary pump include an eccentric screw pump, a vane pump, and a roller pump. In order to supply a mill base having a high viscosity, a diaphragm pump or an eccentric screw pump is preferable. By using the metering pump 11, the dispersibility of the mill base can be stabilized. Moreover, it is preferable that the wetted part is made of a ceramic material such as zirconia or sialon because the wear resistance can be improved.

  The dispersers shown in FIGS. 1 to 3 have a relatively small volume of the container, so that the amount remaining in the container is small. Therefore, there is little loss at the end of dispersion or switching of the mill base, and the structure is simple and cleaning is easy. In addition, since it has a sealed structure, there is little scattering of the solvent, almost no maintenance is required, and even when a high-viscosity mill base is continuously processed, operation is not hindered due to damage to parts. In addition, by using this disperser, a mill base with less dispersal of foreign matters and excellent dispersibility can be obtained.

  The paste production method of the present invention is characterized by using the above-mentioned disperser. The present invention is particularly suitable for producing a paste having a high concentration of inorganic particles and an organic component such as a binder polymer, particularly a phosphor paste used for producing a plasma display.

Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to this. For the mill base used in the examples, three types of pastes (red phosphor paste, blue phosphor paste, and green phosphor paste) used for manufacturing the plasma display panel member were used.
(Paste composition)
(1) Red phosphor paste 35% by weight of (Y, Gd, Eu) BO ₃ (red phosphor) powder having an average particle diameter of 3 μm, 7% by weight of ethyl cellulose, and 58% by weight of terpineol (organic solvent).
(2) Green phosphor paste (Zn, Mn) ₂ SiO ₂ (green phosphor) powder having an average particle diameter of 2.5 μm 33.5 wt%, ethyl cellulose 6.5 wt%, and terpineol (organic solvent) 60 wt% .
(3) Blue phosphor paste (Ba, Eu) MgAl ₁₀ O ₁₇ (blue phosphor) powder having an average particle diameter of 2 μm 33.5% by weight, ethyl cellulose 6.5% by weight, and terpionol (organic solvent) 60% by weight .
(Paste evaluation method)
(1) Viscosity Device: Field type viscometer (Brookfield, model DV-III)
Measurement: rotation speed 3rpm, measurement temperature 25 ℃
(2) Dispersibility Device: Grind gauge (Eriksen, 0-50 μm)
Evaluation: Continuously disperse 900 kg of paste and use 50 g of the paste after the dispersion treatment at the time when 450 kg is discharged after the start of discharge as a sample, observe the size of crushing particles formed from aggregated particles present in the sampled paste after dispersion, I read the scale of the place where the crush appeared. However, when a dense crushing boundary appears between the scales or when the values of the two grooves are different, the scale with the larger number is read and the center of the three measurements is pasted. The degree of dispersion was used.

Judgment: Large numbers indicate poor dispersibility.
(3) Amount of foreign matter 900 kg of paste is continuously dispersed, 20 kg of the dispersed paste of 450 to 470 kg is filtered through a 293 mmφ disk filter (filtration pressure: 0.2 MPa, filter: 500 mesh) after the start of discharge, and then the filter is cleaned. The container was placed in a container, immersed in clean acetone, and washed with an ultrasonic cleaner for 30 minutes. After washing, the washing solution was further filtered through a 25 mmφ disk filter (filtration pressure: 0.05 MPa, filter: nylon net (pore diameter 11 μm)), and the amount of foreign matter remaining on the filter was measured with a precision balance.
Judgment: A large amount of foreign matter indicates that the dispersibility is poor, or that wear powder such as a cylindrical container, a roller and a rotor of the disperser is mixed.
(Roller wear evaluation method)
(1) Number of Roller Chips 900 kg of paste was continuously dispersed, and the number of scraped rollers due to wear of the rollers and the number of roller chips were counted.
(2) Roller scraping amount After dispersing the paste, the roller was placed in a clean container, immersed in clean acetone, and washed with an ultrasonic cleaner for 30 minutes. After washing, the roller was dried on a clean bench for 24 hours, and the weight of the roller was measured with a precision balance and compared with the weight of the roller before dispersion. The dispersers shown in FIGS. 1 and 2 were used as Examples 1 to 4 and Comparative Examples 1 and 2. Table 1 shows the materials and shapes of the cylindrical container, the rotor and the roller. The actual capacity of this disperser was 1.5L.

  A predetermined amount of each paste was weighed and premixed with a planetary mixer (manufactured by Inoue Seisakusho). The conditions at this time were 60 minutes at 60 rpm. After completion of the preliminary mixing, an upper lid was set on the lower pot of the mixer, and connected to a disperser in which a roller was inserted in a cylindrical container with a 1.5S (inner diameter 35.7 mm) metal pipe via a metering pump. Air pressure of 0.2 MPa was applied to the mixer kettle, and the paste in the mixer kettle was extruded into a cylindrical container. The operating condition of the disperser was 300 rpm.

  Table 1 shows the results of measuring the dispersity, viscosity, and amount of foreign matter on the disk filter after the dispersion treatment of each paste, and the number of chipped and scraped rollers.

  The pastes dispersed in Examples 1 to 4 had a small amount of foreign matter and good dispersibility. Also, there was no chipping of the roller and there was little shaving. The paste dispersed in Comparative Examples 1 and 2 had good dispersibility, but a large amount of foreign matter was observed. In addition, chipping of the roller occurred, and there were many shavings.

It is the horizontal surface schematic diagram which showed an example of the disperser by this invention. It is the longitudinal cross-sectional schematic diagram which showed an example of the disperser by this invention. It is an expanded sectional view of the roller vicinity of FIG. It is the front view and side view which showed an example of the shape of the roller which has a taper shape. It is the front view and side view which showed another example of the shape of the roller which has a taper shape. It is the front view and side view which showed another example of the shape of the roller which has a taper shape.

Explanation of symbols

1: cylindrical container 2: rotor 3: rotating shaft 4: groove 5: tapered roller 6: slight gap 7: gap 8: jacket 9: supply port 10: discharge port 11: metering pump 12: lower pot 13: Top lid

Claims (6)

A mill base supply port is provided near one end portion in the central axis direction, a mill base discharge port is provided near the other end portion, and the inner surface in a direction perpendicular to the central axis has a circular cross section in a cylindrical container. A disperser having a rotatable rotor in which a plurality of grooves parallel to the central axis are formed on an outer peripheral portion, and a plurality of rollers arranged to rotate and revolve in the grooves. A taper shape in which the cross section perpendicular to the longitudinal direction is a circle, and the diameter R of the cross section in the central portion and the diameter r of the tip portion on the mill base supply port side satisfy the relationship of the following formula (1) on all or part of the rollers The disperser characterized by using the roller which has.
r / R <0.8 (1) In the plurality of rollers, at least a roller closest to the end of the rotor on the mill base supply port side, and a roller at least a part of which is applied to a circumferential region including the roller of the rotor. The disperser according to claim 1, wherein the disperser has the tapered shape. The end of the groove on the side of the mill base supply port is substantially aligned so as to be aligned with a surface perpendicular to the central axis, and at least the roller closest to the mill base supply port of the groove has the tapered shape. The disperser according to claim 1. The disperser according to any one of claims 1 to 3, wherein the roller having the tapered shape includes a cylindrical portion and a tapered portion having a truncated cone shape. The disperser according to any one of claims 1 to 3, wherein the roller having the tapered shape includes a tapered portion including a cylindrical portion and a part of a sphere or a part of a spheroid. The manufacturing method of the paste which disperse | distributes to-be-dispersed material using the disperser in any one of Claims 1-5.

Images