JP3771557B2 - High pressure disperser and high pressure pump for high pressure disperser - Google Patents

Description

  The present invention relates to a wet disperser that disperses powder composed of solid particles such as ceramic and metal in a solvent. More specifically, for example, a high-pressure disperser that performs an operation of dispersing powder in a solvent under a high-pressure condition of about 200 Mpa to form a slurry and extrudes the slurry at substantially the same pressure, and a high-pressure pump that generates the high-pressure condition About.

  In the manufacturing process of chip-shaped electronic components such as multilayer ceramic capacitors, so-called insulating slurry for ceramic green sheets or metal paste is used as a raw material. These are obtained by making ceramics or metals having desired electrical characteristics into a powder form and mixing these powders in a desired amount in a solvent such as a resin.

  In recent years, chip electronic components have been rapidly reduced in size and performance, and a slurry or the like that can form a thinner insulating layer or metal layer is required. Along with this, the powder used for the slurry and the like has also been refined, and the particle size has reached the order of microns or less. Such fine powder generally has the characteristics that it is easy to agglomerate and its surface is very difficult to wet with a solvent or the like. For this reason, it has become difficult to cope with a stirrer such as a ball mill that has been used to mix powder in a solvent.

  In order to cope with such a fine powder, the powder and solvent, or a quasi-mixture thereof (the powder and the solvent are not completely mixed, but the powder is dispersed in the solvent to some extent in this specification. As described below, a collision dispersion method for obtaining a good mixed state is being studied by colliding under high pressure conditions to break the agglomerated state of the powder and forcibly improve the wettability. FIG. 6 shows a cross-sectional view of the principal part of the specific configuration. The collision unit 50 has a plurality of branch channels 51 a and 51 b therein, and these branch channels merge on the IN side and the OUT side to form a single channel 51. The confluence point on the OUT side of the branch flow path becomes the collision action portion 51c. The quasi-mixed powder and solvent are introduced under high pressure from the end of the IN-side flow path 51 and branched into each of the branch flow paths 51a and 51b inside the collision unit. The streams impinge and the powder and solvent are remixed.

  In this method, it is essential to apply a high pressure to the semi-mixed solvent or the like. FIG. 7 shows a schematic cross-sectional view of the configuration of the main part of the high-pressure pump used to generate the high pressure. The high-pressure pump 100 fixes a substantially cylindrical cylinder 101, a plunger 103 that reciprocates inside the cylinder, a seal member 105 disposed between the outer periphery of the plunger and the inner peripheral wall of the cylinder, and the seal member. And a fixing ring 107. The seal member 105 has an action of maintaining the hermeticity of the space 109 formed by the cylinder 101 and the plunger 103.

  The semi-mixed solvent or the like is introduced into the sealed space 109, and the plunger 103 moves to the vicinity of the end of the cylinder 101 (left side in the figure) to obtain a high pressure, and then is discharged from the sealed space 109. (See Patent Document 1). By disposing the high-pressure pump 100 having the above configuration upstream of the collision unit 50, it is possible to easily and effectively apply a high pressure to a semi-mixed solvent or the like. Note that a normal high-pressure pump is intended only for fluids, and is not used for fluids containing solid particles. Therefore, when this is used to apply a high pressure to a semi-mixed solvent or the like targeted by the present invention, it is required to modify the configuration of the high-pressure pump in consideration of the solid particles.

  Specifically, the solid particles adhere to the outer peripheral portion of the plunger 103, thereby promoting the wear of the seal member 105 caused by the reciprocating motion of the plunger 103 and abruptly promoting the deterioration of the sealing performance. It is possible. For this reason, in order to adapt to the application, a configuration has been devised in which a chamber for cleaning the surface of the plunger 103 is provided on either side of both end faces of the seal member 105 (see Patent Document 2). In Patent Document 2, it is stated that by providing such a cleaning chamber and circulating a cleaning liquid inside the chamber, it is possible to reduce wear caused by solid particles and the like, and the life of the seal member is greatly extended. ing.

Japanese Patent Laid-Open No. 10-306776 JP 2001-241385 A

  In Patent Document 2, it has been confirmed that continuous operation for several hundred hours is possible under the condition of obtaining a pressure of 100 MPs. However, when the apparatus is used in an actual production process, it is necessary to obtain a high pressure of 200MPs or more when the individual particle size of the powder is on the order of microns or less. It is indispensable to obtain this high pressure for the ceramic slurry or metal paste for electronic parts targeted by the present invention, and it is expected that this pressure will become higher in the future. When the present inventor confirmed the operation time of the apparatus from such a viewpoint, the lifetime of the high-pressure seal member was only about 50 to 60 hours. Therefore, when it is going to use the apparatus for producing a desired slurry in the future, even if a powder having a smaller particle diameter is used, the life of the seal member is extended to obtain a continuous operation time of several hundred hours or more. It is necessary to build a configuration that can be used.

  The present invention has been made in view of the above situation, and aims to extend the life of the high-pressure seal member of the plunger sliding portion in the high-pressure pump, thereby increasing the operating time of the high-pressure disperser. The purpose is to save time. Another object of the present invention is to achieve stable production of slurry and shorten downtime of equipment by achieving the object.

  In order to solve the above-mentioned problems, the high-pressure disperser according to the present invention is a high-pressure disperser that uniformly disperses solid particles in a mixture by mixing fine solid particles in a solvent and using high pressure conditions. A disperser, a high-pressure pump that applies high pressure to the mixture, and is arranged in a substantially cylindrical cylinder and movably inside the cylinder so as to change the volume of the space inside the cylinder. A cylindrical plunger that causes the plunger to pass therethrough, an annular seal member through which the plunger passes to make the space inside the cylinder a sealed space, and a plunger that is disposed behind the seal member with respect to the space inside the cylinder and the plunger A high-pressure pump having a cylindrical guiding member that is pierced and regulates the movement direction of the plunger so as to be slidable, and the mixture after high pressure is applied by the high-pressure pump flows in The high-pressure pump has an introduction port, a plurality of flow paths branched from the introduction opening, a collision unit having a plurality of flow paths merged at a predetermined position and a discharge port communicating from the merge point. Furthermore, it has an internal space that contacts the plunger surface, the guiding member or the inner peripheral surface of the guiding member, and a cooling medium whose temperature is controlled is circulated inside the internal space.

  In the above-described high-pressure disperser, the cooling medium preferably has the same component as the main component of the solvent, and is controlled to a temperature not lower than the freezing point of the cooling medium and not higher than room temperature.

  In order to solve the above problems, a high-pressure pump according to the present invention is a high-pressure pump that applies high pressure to minute solid particles and a solvent mixed with solid particles, and a substantially cylindrical cylinder; A cylindrical plunger that is movably arranged inside the cylinder and changes the volume of the space inside the cylinder to generate high pressure, and an annular seal that penetrates the plunger and makes the space inside the cylinder a sealed space And a cylindrical guiding member that is disposed behind the seal member with respect to the space inside the cylinder and that allows the plunger to pass therethrough so as to slidably restrict the moving direction of the plunger, and the plunger surface, the guiding member Or it has the internal space which contacts the internal peripheral surface of a guide member, and the cooling medium by which temperature was controlled was circulated inside the internal space.

  In devising the configuration according to the present invention, the deterioration mechanism of the high-pressure seal member found by the present inventors will be briefly described here, and the effect of the present invention on the mechanism will be described. Although described in detail in the embodiment, a substantially cylindrical shape that substantially resists high pressure received from the sealed chamber and restricts movement of the plunger other than in the axial direction is provided behind the high-pressure seal member as viewed from the sealed chamber. A guiding member is disposed. In order to exhibit the above-described action, the guiding member needs to be in close contact with the inner peripheral surface of the guiding member while being slidable with respect to the outer peripheral surface of the plunger. Therefore, when the plunger moves back and forth in the axial direction, frictional heat is generated at the contact portion with the plunger.

  Due to this frictional heat, the slurry adhering to the plunger surface is solidified, and for example, metal powder having a lubricating action without any solvent adheres to the plunger surface or the inner peripheral surface of the guiding member. These metal powders and the like can be removed from the plunger surface by coming into contact with the solvent or the cleaning liquid disclosed in Patent Document 2 again if the particle size is a certain level or more. However, in the case of a metal powder or the like having a small particle diameter, which is an object of the present invention, the surface of the powder is active, and thus the powder that is integrally attached is firmly adhered to the plunger surface. Therefore, in order to remove them, it is necessary to perform a special process such as blowing ionized gas, and it seems difficult to remove them by merely moving the plunger in the cleaning liquid.

  The metal powder or the like adhered to the plunger surface reaches the inner peripheral surface of the high-pressure seal member as the plunger moves. Due to the presence of these metal powders and the like, deterioration of the high pressure seal member due to friction between the plunger surface and the inner peripheral surface of the high pressure seal member rapidly proceeds. Therefore, in the method using the cleaning liquid shown in Patent Document 2, it is difficult to suppress the deterioration of the high-pressure seal member, and this tendency is considered to become more prominent as the metal powder or the like becomes finer.

  As in the present invention, by controlling the temperature of the plunger surface or the temperature of the inner peripheral surface of the guiding member, the plunger surface in the state of metal powder or the like is prevented by preventing a state where a large amount of solvent is desorbed from the slurry. Solid particles are prevented from sticking. Therefore, by implementing the present invention, the life of the high pressure seal member is extended to several hundred hours, and the collision dispersion method can be used in the actual production process.

  Note that examples of the member that adheres to the plunger surface to such an extent that frictional heat is generated include a high-pressure seal member and a guiding member. However, since the high-pressure seal member is disposed near the sealed space where the quasi-mixture exists, heat can be released through the quasi-mixture itself, and it is considered that a rapid temperature rise does not occur. Even if the temperature rise is large, it is considered that a large amount of the solvent is hardly desorbed from the slurry in this region because the contact area is small. Moreover, it seems easy to prevent the metal powder from sticking to the high-pressure seal member by controlling the temperature of the slurry itself. Therefore, it seems to be most effective to cool the inner peripheral portion of the guiding member that has a large contact area and does not have a medium for releasing heat nearby.

  In the present invention, in order to control the temperature of the plunger surface and the like, terpineol, which is one material constituting the slurry, is used as a coolant, and this is brought into contact with the plunger surface behind the high-pressure seal member. I am going to do that. Therefore, even if the coolant enters the sealed chamber beyond the high-pressure seal member, there is no adverse effect on the properties of the slurry. The cooling medium is not limited to terpineol, and is not limited to this as long as it has the same components as the main components of the material constituting the slurry. In addition, the management temperature of the cooling medium may be controlled to be above the freezing point of the medium and below room temperature.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a high-pressure disperser according to an embodiment of the present invention. The high-pressure disperser 1 according to the present invention includes a first flow path system 10 and a second flow path system 30. From the upstream side of the first flow path system 10, the stirring tank 11, the diaphragm pump 13, the first reverse support valve 15, the high pressure pump 20, the second reverse support valve 17, the collision unit 50, and the three-way valve 19 are arranged in this order. Is arranged in.

  The stirring tank 11 is first mixed with a metal powder or the like and a solvent containing terpineol, and stirred by the stirring blade 11a to obtain a fluid semi-mixture 18. The semi-mixture 18 is sent to the downstream side by the diaphragm pump 13, passes through the first counter-support valve 15, and is sent to the high pressure region. Downstream of the first counter-support valve 15, the high pressure pump 20 applies a high pressure of 200 MPa to the semi-mixture. The first reverse support valve 15 prevents this high pressure from being applied upstream from the first reverse support valve 15.

  The semi-mixture to which high pressure is applied passes through the second counter-support valve 17 and is sent to the collision unit 50. The high-pressure pump 50 does not always maintain a pressure of 200MPs, and when the plunger is retracted, the pressure is significantly lower than this. In this low pressure state, the second counter-support valve 17 prevents the back flow of the semi-mixture that has passed through the counter-support valve and maintained at a high pressure. Since the collision unit 50 has already been described in detail, a description thereof is omitted here. The semi-mixture in which the dispersion state of the metal powder or the like has been improved through the collision unit 50 is sent again to the stirring tank 11 in the three-way valve 19. The semi-mixture circulates through the series of flow paths a plurality of times, whereby a slurry having a good dispersion state can be obtained. The slurry and the like are discharged from the three-way valve 19 after being circulated a predetermined number of times and sent to the next step.

  The second flow path system 30 is used for cooling a plunger and a guiding member described later in the high-pressure pump 20 and controlling the surface temperature of the plunger or the temperature of the inner peripheral surface of the guiding member. The second flow path system 30 is arranged in the order of the cooling medium tank 31, the cooling tank 33, the diaphragm pump 35, and the high-pressure pump 20 from the upstream side. The cooling medium 37 placed in the cooling medium tank 31 is cooled by passing through the cooling tank 33 and the temperature thereof is managed. The cooling medium is introduced into the high-pressure pump 20 by the diaphragm pump 35. Inside the high-pressure pump 20, the flow path is formed so that the cooling medium lowers the temperature of the plunger surface in the vicinity of the guiding member or the inner peripheral surface of the guiding member. The cooling medium returns to the cooling medium tank 31 after cooling these predetermined portions.

  In addition, each structure in the high voltage | pressure disperser 1 mentioned above is an illustration to the last, and can be substituted with the various structure which has an equivalent effect | action. Specifically, the stirring tank may not have stirring blades, or the stirring tank may be a ball mill or the like to further increase the stirring efficiency. Moreover, it is preferable that a diaphragm pump, a reverse valve, etc. are suitably changed according to the characteristic of a semi-mixture, for example.

  Further, terpineol is used as the cooling medium, which is because a solvent containing terpineol is used. That is, even if mixed in the solvent, various fluids can be used as the cooling medium as long as the properties of the slurry to be produced are not altered. In addition, the temperature at which the cooling medium is cooled is preferably low, but it may be not less than the freezing point of the cooling medium and not more than room temperature. When terpineol is used as a cooling medium, a suitable temperature range is considered to be -5 ° C or higher and 20 ° C or lower. In order to increase the cooling efficiency, it is preferable that the flow path of the cooling medium has a size that can secure a sufficient flow rate.

  Next, regarding the high-pressure pump for a high-pressure disperser according to the present invention, a flow path and the like provided for specifically cooling the plunger surface and the like will be described below. In the description, in order to facilitate understanding of the features of the high-pressure pump according to the present invention, the high-pressure seal member in the configuration of the high-pressure pump described in the background art, the configuration disposed in the vicinity thereof, and the characteristic portion in the present invention Only the configuration related to will be described.

  FIG. 2 is a schematic cross-sectional view of the high-pressure pump 20 according to the embodiment of the present invention, and shows each component in the vicinity of the high-pressure seal member. Note that the above-described sealed space in the high-pressure pump 20 exists on the left side in the drawing. The high-pressure pump 20 includes an annular first lantern ring 21, an annular high-pressure seal member 22, an annular backup ring 23, an annular second lantern ring 24, and a guide member 25 from the sealed space side (not shown). Are arranged in that order. Plungers 26 pass through the central holes of the individual members. The cylinder 27 has a substantially cylindrical shape, and the cylindrical hole has a portion whose inner diameter varies depending on each member. Therefore, by fixing the guiding member 25, all of these annular members are substantially fixed at predetermined positions.

  The first lantern ring 21 has an effect of directly receiving the pressure from the semi-mixture and applying the pressure equally to the high-pressure seal member 22. The high-pressure seal member 22 is deformed by the applied pressure, and the inner and outer circumferences thereof need to be in close contact with the plunger 26 surface and the inner circumferential surface of the cylinder 27, respectively. The backup ring 23 has a function of supporting the high-pressure seal member 22 and assisting the high-pressure seal member 22 to change stably and uniformly in the circumferential direction. Accordingly, the inner and outer peripheries of the first lantern ring 21 and the backup ring 23 are not in contact with the plunger 26 surface and the inner peripheral surface of the cylinder 27.

  The second lantern ring 24 prevents the backup ring 23 from applying a local additional load to the fixed guiding member 25 and stably supports the backup ring 23 in a larger area. Have. Therefore, none of the second lantern rings 24 comes into contact with the surface of the plunger 26 or the inner peripheral surface of the cylinder 27. The guiding member 25 has its rear end fixed by fixing means (not shown), and is in contact with the second lantern ring 24 at its front end.

  Since the guiding member 25 is required to regulate the displacement of the plunger 26 in the radial direction and to easily move in the axial direction, the guiding member 25 is disposed in contact with the surface of the plunger 26. Therefore, from the viewpoint of preventing wear loss with the plunger, it is made of an elastic material such as resin instead of metal. Since the guiding member 25 is present in an arrangement that finally receives a high pressure in the sealed space, the guiding member 25 is elastically deformed by the pressure. Close contact with the peripheral surface.

  The guiding member 25 has a guiding member internal space 25 a that comes into contact with the surface of the plunger 26 so as to wind the surface of the plunger 26. The space 25 a communicates with an introduction port 27 a and a discharge port 27 b provided in the cylinder 27. By introducing the cooling medium described above into the guiding member internal space 25a from the introduction port 27a, the cooling medium flows on the surface of the plunger 26 and cools it. The cooling medium that has cooled the surface of the plunger 26 is then discharged to the outside through the discharge port 27b.

  By making the configuration of the high-pressure pump as described above, the adhesion of the metal powder or the like to the plunger surface in the vicinity of the guiding member 25 and the vicinity found by the present inventor is greatly reduced, and the life of the high-pressure seal member is extended. Is done. In addition, the said cooling medium also has the washing | cleaning effect | action of the plunger surface simultaneously, The effect which wash | cleans the part considered to be the most effective for the lifetime extension of the high-pressure seal member which this inventor found out is also acquired.

  In FIG. 3, the modification about the structure of the high pressure pump 20 is shown. In the present modification, the space formed in the guiding member 25 in the above-described embodiment is different from the portion formed in the second lantern ring 24. The lantern ring internal space 24 a communicates with an introduction port 27 a and an exhaust port 27 b provided in the cylinder 27. Since there is no particularly different part with respect to the other configurations, description thereof will be omitted. This configuration is inferior to the previous embodiment from the viewpoint of effectively cooling the problematic part. However, in consideration of the fact that high pressure is applied, it is appropriate to obtain a higher pressure with this configuration than to provide a space for a relatively low strength guiding member. I can say that. However, the formation position of the space is preferably provided at a position closer to the guiding member from the viewpoint of preventing re-generation of the metal powder.

  FIG. 4 shows a case where a baffle plate 24b that disturbs the flow of the cooling medium is further provided inside the lantern ring inner space 24a in addition to the above-described modification. By disposing the baffle plate 24a, it is possible to effectively cool a region closer to the guiding member. Depending on the type of the cooling medium to be used, the cooling efficiency may be further improved by adding such a configuration.

  As an example of the present invention, when terpineol is used as a cooling medium, the temperature is controlled to 14 to 18 ° C., and the temperature of the cooling medium is not controlled, and the effect of the cooling medium is only a cleaning effect. And compared. FIG. 5 shows the result. FIG. 5 shows the temperature at two positions of the plunger when the temperature control of the cooling medium is not performed, the temperature of the slurry immediately after being discharged from the pump, and the plunger 2 when the temperature control of the cooling medium is performed. The temperature at the point and the temperature of the slurry are determined as the A condition and the B condition, respectively, and the results change with time.

  According to the figure, about 30 minutes after the start of the operation of the high-pressure pump, the plunger of the B condition becomes a constant temperature, and no large temperature change is shown thereafter. Further, the temperature of the slurry also shows a substantially constant temperature of 50 ° C. or less. Compared with this, in the condition A, the slurry temperature shows a value close to 100 ° C. immediately after the operation. Since the slurry temperature is high, the friction coefficient in the condition A is lower than that in the condition B, and the heat generation due to the friction is considered to be smaller than the condition B. However, although it is necessary to consider the influence of the slurry temperature, the temperature of the plunger in the condition A continues to rise.

  Further, as additionally shown in the figure, in condition A, an abnormal sound is generated 40 minutes after the start of operation. This indicates that an abnormal frictional state has occurred, and it seems that a large amount of metal powder or the like has already adhered to the plunger surface. Actually, under the condition A, the seal member was broken after about 50 to 60 hours of operation time. In comparison with this, the operating time of about 300 hours was obtained under the condition B, and the superiority of the present invention was clearly confirmed.

  The above-described embodiment and the like describe a high-pressure disperser used for manufacturing a slurry for forming a ceramic green sheet or a metal paste used as a raw material when manufacturing a chip-shaped electronic component. However, the high-pressure disperser according to the present invention and the high-pressure pump used in the high-pressure disperser, when using a magnetic material such as ferrite, when forming a carbon-containing paint, etc. It can be used to uniformly disperse in a solvent under the above high pressure environment.

It is a figure which shows schematic structure of the high voltage | pressure disperser which concerns on this invention. It is sectional drawing which shows schematic structure of the principal part regarding the pump for high pressure dispersers which concerns on embodiment of this invention. It is sectional drawing which shows schematic structure of the principal part of the modification regarding the pump for high pressure dispersion machines concerning embodiment of this invention. It is sectional drawing which shows schematic structure of the principal part of the modification regarding the pump for high pressure dispersion machines concerning embodiment of this invention. FIG. 4 is a diagram illustrating changes in plunger and slurry temperatures with time for an example of the present invention. It is a figure which shows schematic structure of a collision unit. It is sectional drawing which shows the principal part regarding the conventional structure of a high pressure pump.

Explanation of symbols

1: High pressure disperser 10: First flow path system 11: Stirring tank 13: Diaphragm pump 15: First reverse branch valve 17: Second reverse branch valve 18: Semi-mixture 19: Three-way valve 20: High pressure pump 21: First One lantern ring 22: high pressure seal member 23: backup ring 24: second lantern ring 25: guide member 26: plunger 27: cylinder 30: second flow path system 31: cooling medium tank 33: cooling tank 35: Diaphragm pump 37: Cooling medium 50: Collision unit 51: Slurry flow path 100: High pressure pump 101: Cylinder 103: Plunger 105: Seal member 107: Fixed member

Claims (2)

A high-pressure disperser that mixes fine solid particles in a solvent and uniformly disperses the solid particles in the mixture in the solvent by using high pressure conditions,
A high-pressure pump that applies high pressure to the mixture, and is arranged in a substantially cylindrical cylinder and movably inside the cylinder to change the volume of the space inside the cylinder to generate high pressure. A cylindrical plunger, an annular seal member through which the plunger penetrates to make the space inside the cylinder a sealed space, and a space behind the seal member with respect to the space inside the cylinder and the plan A high-pressure pump having a cylindrical guiding member through which a jar is pierced so as to slidably regulate the moving direction of the plunger;
An introduction port into which the mixture after high pressure is applied by the high-pressure pump, a plurality of flow channels branched from the introduction port, a merge point where the plurality of flow channels merge at a predetermined position, and the merge A collision unit having a discharge port communicating from the point,
The high-pressure pump further has an inner space that contacts the plunger surface, the guiding member or the inner peripheral surface of the guiding member, and a cooling medium whose temperature is controlled is circulated inside the inner space ,
The high-pressure disperser characterized in that the cooling medium has the same components as the main components of the solvent and is controlled to a temperature not lower than the freezing point of the cooling medium and not higher than room temperature .   A high-pressure pump that applies high pressure to fine solid particles and a solvent mixed with the solid particles,
  A substantially cylindrical cylinder;
  A cylindrical plunger that is movably disposed inside the cylinder and changes the volume of the space inside the cylinder to generate a high pressure;
  An annular seal member through which the plunger penetrates to make the space inside the cylinder a sealed space;
  A cylindrical guiding member that is disposed behind the seal member with respect to the space inside the cylinder and that allows the plunger to pass therethrough and regulates the movement direction of the plunger so as to be slidable;
  An inner space that contacts the plunger surface, the guiding member or the inner circumferential surface of the guiding member;
  A cooling medium whose temperature is controlled is circulated inside the internal space,
  The high-pressure pump characterized in that the cooling medium has the same component as the main component of the solvent and is controlled to a temperature not lower than the freezing point of the cooling medium and not higher than room temperature.

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