JP2005104070A - Manufacturing method of slurry, ceramic green sheet and conductive paste - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of slurry effectively dispersing fine material powder by use of a high pressure homogenizer while generating neither cavitation nor bubbling. <P>SOLUTION: The manufacturing method of slurry conducts a dispersing operation by giving high pressure to roughly dispersed liquid obtained by preliminarily mixing the raw material powder and a dispersing medium to make the roughly dispersed liquid flow at a high speed. Back pressure is given to the dispersed portion, and the back pressure is stepwise given to the downstream side of the dispersed portion to reduce the slurry pressure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a slurry production method using a high-pressure homogenizer, a ceramic green sheet which is a molded body of a ceramic slurry obtained by the slurry production method, and a conductive paste obtained by adding an organic vehicle to the conductive slurry. .

  In order to reduce the size and functionality of ceramic electronic components, it is important to form ceramic green sheets and conductive paste coatings that are thin but have high strength and excellent smoothness.

  Ceramic slurry and conductive paste for such applications are obtained by dispersing conductive powder made of ceramic raw material powder, metal powder, etc. in a dispersion medium made of solvent, dispersant, binder, etc. It is a thing. In order to obtain a ceramic green sheet or a conductive paste coating film having the above-mentioned characteristics, the raw material powder is finely divided into submicron order or smaller particle size, and in the ceramic slurry or conductive paste. These fine particles are required to be pulverized and dispersed to primary particles or a particle size close to the primary particles, and to have high filling properties in the coated ceramic green sheet or conductive paste coating film.

  However, if the raw material powder is made finer, on the other hand, the cohesiveness also becomes higher and it becomes easier to form secondary particles having a large particle size, making it difficult to produce highly dispersible ceramic slurries and conductive pastes. It becomes.

  Conventionally, in order to sufficiently disintegrate this agglomerated structure, the raw material powder is mechanically affected by the impact force of the media or roll by using a ball mill, a sand mill or the like for a ceramic slurry, or a three roll for a conductive paste. A method of crushing and dispersing in a dispersion medium has been used.

  However, when the raw material powder is dispersed by the above-described method, there is a problem of generation of fine powder due to excessive grinding in the ceramic raw material powder, and generation of flat powder due to ductility in the metal powder. It was difficult to disperse the particles to primary particles or a particle size close to them and to disperse them well in the dispersion medium.

  By the way, as a device that can efficiently emulsify, atomize, or highly disperse various raw materials in the fields of pharmaceuticals, cosmetics, chemicals, and food products, a high-pressure homogenizer (see Patent Documents 1 and 2). Has been used as a useful tool.

A high-pressure homogenizer applies a high pressure to a crude dispersion premixed with raw materials and a dispersion medium, and suddenly drops the pressure by passing the pressurized coarse dispersion through a narrow gap or small-diameter orifice. By accelerating the liquid, a high-speed fluid jet is used to emulsify and disperse by a mechanism such as a shear wave of the fluid jet, a collision force, and a shock wave accompanying cavitation caused by a pressure difference.
JP 2000-33249 A Patent No. 2976526 gazette Therefore, also in the production of ceramic electronic components, application of the high-pressure homogenizer has been studied in order to produce highly dispersible ceramic slurry and conductive paste using fine raw material powder. .

  In the case of dispersion using the high-pressure homogenizer described above, the kinetic energy is extremely large, and large cavitation or bubbling easily occurs, resulting in a loss of load pressure. Needed.

  In addition, the dispersion of the raw material powder is a so-called steric hindrance effect that occurs when the gas phase on the surface of the powder is replaced by a dispersion medium, and is further adsorbed and replaced by a dispersant such as a surfactant or a binder such as a binder resin. Based on However, if a large amount of gas phase is present in the dispersion medium due to cavitation, the gas phase on the powder surface is not easily replaced by the dispersion medium, and the resin component of the dispersant or binder is adsorbed on the gas-liquid interface. Since it becomes easy, the above-mentioned sequential replacement becomes difficult and the dispersion efficiency deteriorates.

  Therefore, although it is necessary to suppress the generation of the gas phase due to this cavitation, on the other hand, as shown in Patent Document 1, the high-pressure homogenizer generally has a shock wave accompanying cavitation generated in the dispersion part, Used for emulsification and dispersion. However, when fine particles having a particle size of 1 μm or less are dispersed, the above-mentioned steric hindrance effect is indispensable, and the occurrence of cavitation is inconvenient.

  For the purpose of reducing the load pressure and the number of dispersion processes, Patent Document 2 proposes to apply a small back pressure of 0.2 to 5% with respect to the processing pressure. However, even when such back pressure is applied, the pressure difference between the upstream and downstream of the back pressure load device is still large, and depending on the flow path design, there is a possibility of generating cavitation or bubbling on the downstream side of the back pressure load device. In the case of dispersing fine particles having a high particle diameter of 1 μm or less, the above-mentioned steric hindrance effect cannot be obtained, which is inconvenient.

  The present invention provides a slurry manufacturing method in which a high-pressure is applied to a crude dispersion preliminarily mixed with a raw material powder and a dispersion medium, and the dispersion process is performed by flowing at high speed. It is characterized in that the back pressure is applied stepwise and the slurry pressure is lowered on the downstream side of the section.

  Further, the slurry is cooled in the dispersion portion.

  In addition, the slurry is cooled before the slurry pressure is lowered on the downstream side of the dispersion portion.

  In addition, the slurry is cooled before the slurry pressure is lowered on the dispersion part and on the downstream side of the dispersion part.

  Furthermore, in a slurry manufacturing method in which a dispersion treatment is performed by applying a high pressure to a crude dispersion obtained by premixing raw material powder and a dispersion medium and flowing at high speed, the slurry is cooled in the dispersion section. .

  According to the present invention, since the slurry pressure is stepped down on the downstream side of the dispersion part and the dispersion part and the slurry is cooled, generation of a gas phase due to cavitation caused by a pressure difference or bubbling can be suppressed. In addition, a decrease in wettability to the dispersion medium due to adsorption of a gas phase on the surface of fine ceramic raw material powder or metal powder is suppressed. In addition, since the resin components such as the dispersant and the binder are adsorbed on the surface of the fine ceramic raw material powder or metal powder without adsorbing on the gas-liquid interface, the raw material based on the steric hindrance effect by the above-mentioned sequential substitution The dispersion efficiency of the powder can be increased.

  Moreover, the local dry solidification accompanying the volatilization of the dispersion medium into the gas phase is suppressed, and the resin component adsorbed on the gas-liquid interface exists as a lump in the ceramic green sheet or the conductive paste coating film. To suppress that.

  Due to the above-described effects, a ceramic green sheet or a conductive paste coating film that is thin but has high strength and excellent smoothness can be obtained, so that a multilayer ceramic capacitor having good characteristics can be obtained.

  Hereinafter, the manufacturing method of the slurry of this invention is demonstrated according to drawing.

  FIG. 1 is a conceptual diagram of a production apparatus showing a slurry production method according to the present invention. That is, the coarse dispersion previously mixed by the preliminary mixing system is supplied from the charging tank 1 to the pressurizing unit 2 through the charging line 7. The coarse dispersion is loaded with a high pressure by passing through the pressurizing unit 2, and is supplied to the dispersing unit 3 through the dispersing unit supply line 8. The dispersion unit 3 will be described with reference to FIG. The pressurized coarse dispersion becomes a high-speed fluid jet in the dispersion unit 3, and when the kinetic energy of the fluid jet is converted into shear energy, the raw material powder in the coarse dispersion is dispersed and becomes a slurry. The dispersed slurry passes through the cooling unit supply line 9 and is supplied to a slurry cooler 6 provided immediately after the dispersing unit 3 that cools the slurry temperature raised in the dispersing unit 3 to a room temperature or lower. The slurry cooled by the slurry cooler 6 is discharged to the discharge tank 5 through the discharge line 10 provided with the back pressure load portion 4 for stepwise reducing the slurry pressure. The back pressure load portion will be described with reference to FIG. Further, by providing a re-feeding line 11 that can re-feed the slurry after the above-described processing from the discharge tank 5 to the charging tank 1, continuous processing for further improving dispersibility can be performed.

  The pumping capacity of the pressurizing unit 2 is set in accordance with the flow speed and production volume of the fluid jet necessary for obtaining a desired slurry. In the present invention, the pressure applied to the crude dispersion is suitably 10 to 400 MPa, particularly preferably 100 to 300 MPa.

  The dispersion unit 3 may be of a conventional model used as a high-pressure homogenizer dispersion method such as Microfluidizer, Manton-Gorin, Nanomizer, Sugino Machine, and Genus. The structure shown in 2 sectional drawing is mentioned.

  The coarse dispersion liquid loaded with a high pressure in the pressurizing unit 2 passes through the dispersion unit orifice 12 and becomes a high-speed fluid jet due to the acceleration of the liquid accompanying a rapid pressure drop. This fluid jet is ejected into the jet space 13. The flow velocity in the dispersion portion orifice 12 is suitably from 100 to 1500 m / s, and particularly preferably from 200 to 1000 m / s, since the dispersion efficiency can be further increased.

  The material of the dispersion part orifice 12 is excellent in wear resistance such as diamond when producing a slurry containing ceramic raw material powder having a high pressure applied to the coarse dispersion liquid of 100 MPa or more and high wear resistance. It is necessary to use a material.

  In the present invention, the fluid jet ejected from the dispersion orifice 12 flows at high speed in the jet space 13 filled with the slurry. The fluid jet is decelerated by the shearing stress generated at that time. When this shear stress acts on the slurry in the jet space 13, the secondary particles contained in the slurry are crushed and dispersed into primary particles.

  The degree of deceleration is determined by the inner diameter and length of the jet space 13, and is preferably set so as not to have kinetic energy at the end of the jet space. The structure of the jet space 13 is preferably cylindrical.

  The diameter of the dispersion portion orifice 12 is set in accordance with the required speed of the fluid jet and the production amount of the slurry, but 0.005 to 1.0 mm is appropriate, and in particular 0.05 to 0.5 mm. Is preferred.

  The inner diameter of the jet space portion 13 needs to be larger than the diameter of the dispersion portion orifice 12, but if it is too large, a region where the flow velocity is zero, called a stagnation region inside the jet space, is generated, which causes a decrease in dispersibility. Absent. On the other hand, if it is too small, a high-speed fluid jet wears the inner wall of the jet space 13, which is not preferable.

  Specifically, although depending on the structure of the dispersion part orifice 12 and the flow velocity in the dispersion part orifice, the inner diameter of the jet space part 13 is suitably 2 to 200 times the diameter of the dispersion part orifice 12, particularly 4 ~ 100 times is preferable.

  Moreover, although the length of the jet space part 13 is based also on the flow velocity of a fluid jet, the internal diameter of a jet space part, and slurry viscosity, 10-500 mm is preferable.

  Furthermore, it is preferable that the terminal portion of the jet space is designed so that the distribution portion orifice inner diameter <the end portion inner diameter <the jet space inner diameter.

  The back pressure can be obtained by applying a load to the flow of the slurry. The structure of the back pressure load portion 4 is not particularly limited as long as a desired back pressure can be obtained. For example, when producing a slurry containing ceramic raw material powder having a high back pressure of 30 MPa or more and high wear resistance, it is made of a material having excellent wear resistance, such as diamond, as shown in the sectional view of FIG. It is necessary to have a structure in which the flow rate is reduced by the back pressure load portion orifice 14.

  On the other hand, when the desired back pressure is low or there is little concern about wear such as dispersion or emulsification of the resin component, as shown in the cross-sectional view of FIG. 4, a cylindrical long back pressure load portion made of stainless steel, zirconia or the like A back pressure can be applied in the flow path 15.

  The flow path design described above is optimized taking into account the desired back pressure, slurry wear, running costs, material processability, and the like.

  FIG. 7 is a conceptual diagram illustrating a slurry manufacturing method and manufacturing apparatus according to another embodiment of the present invention.

  In FIG. 7, by directly injecting the refrigerant into the dispersion part 3, the slurry that has become high temperature in the high-pressure dispersion treatment is cooled, and the dispersion efficiency of the raw material powder is increased by suppressing the occurrence of cavitation. FIG. 8 shows a cross-sectional view of the dispersing portion 3.

  In FIG. 8, since the fluid jet ejected from the dispersion orifice 12 flows at high speed in the jet space 13 filled with the slurry, the refrigerant injection part 19 connected to the jet space 13 is naturally negative. Become pressure. Therefore, the refrigerant cooled from the refrigerant charging part 16 through the refrigerant cooler 18 easily flows into the dispersion part 3 through the refrigerant injection part 19. However, it is possible to inject more easily and to easily control the injection amount when a slight back pressure is applied by the refrigerant pressurizing unit 17, so that the slurry can be effectively cooled.

  Examples of the results of actually producing a slurry using this invention and confirming the effect are shown below.

  2 parts by weight of anionic dispersant, 10 parts by weight of acrylic resin binder, and 100 parts by weight of toluene with respect to 100 parts by weight of barium titanate dielectric ceramic raw material powder having an average particle size of 0.2 μm Were premixed with a mixer to obtain a crude dispersion.

  Next, by using the slurry production apparatus shown in the conceptual diagram of FIG. 1 described above, by applying a pressure of 200 MPa in the pressurizing unit and passing through a dispersion part made of a dispersion part orifice made of diamond having a diameter of 0.1 mm, A high-speed fluid jet was slurried.

  In addition, the slurry cooled between the dispersion part and the first back pressure load part from the upstream side was cooled to about 10 ° C. with the slurry whose temperature was increased to about 80 ° C. by high-pressure dispersion treatment. .

  In addition, the back pressure load part is 20 MPa at the first from the upstream side, 5 MPa at the second, 1.5 MPa at the third, 0.5 MPa at the fourth, 0.2 MPa at the fifth, and 0.1 MPa at the sixth. Was set to be.

  As a result, a 10% back pressure is applied to the dispersing portion, and when the slurry flows through the discharge line, the slurry pressure is gradually reduced.

  In order to improve dispersibility, this high-pressure dispersion treatment was repeated 10 times to obtain a slurry by the production method according to the present invention.

  On the other hand, only the slurry cooled by the slurry cooler was applied to the high-temperature slurry discharged from the dispersion section, and a slurry produced by repeating the high-pressure dispersion treatment 10 times without applying a back pressure was obtained as a comparative example.

  As shown in Table 1, the dispersibility of the slurry thus obtained was measured using a particle size distribution measuring device manufactured by Microtrac Co., Ltd. using an integrated 50% particle size (D50) of the particle size distribution as an index. Results were obtained.

  As shown in Table 1, by applying back pressure, cavitation generated by pressure difference or generation of gas phase due to bubbling can be suppressed, so D50 should be made smaller than when no back pressure is applied. Can do. That is, dispersibility can be further improved.

  Next, the slurry by the manufacturing method concerning this invention was shape | molded by the doctor blade method in the sheet form, and the ceramic green sheet was obtained. The thickness of the obtained ceramic green sheet was 10 μm.

  And surface roughness Ra (arithmetic mean roughness calculated | required from the roughness curve of JISB0601) of the obtained ceramic green sheet was measured with the atomic force microscope, and also the measured density with respect to the theoretical density of a ceramic green sheet When the ratio (density ratio) was determined, Ra was 60 nm and the density ratio was 1.00.

  The density ratio indicates that the closer to 1.00 the measured density is closer to the theoretical density, that is, there is no void and the ceramic green sheet has good filling properties. If the slurry contains a large amount of coarse secondary particles generated by aggregation of primary particles, the filling of the raw material powder deteriorates during sheet molding, so there are fine voids in the ceramic green sheet after drying. Present, and the density ratio will decrease.

  That is, it was found that a ceramic green sheet having excellent smoothness and filling property was obtained by forming a slurry having good dispersibility according to the production method of the present invention.

  Moreover, using this ceramic green sheet, a multilayer ceramic capacitor 21 as shown in FIG. 5 was obtained.

  The multilayer ceramic capacitor 21 includes an element body 22 made of a dielectric ceramic, and a plurality of sets of element bodies 22 are opposed to each other via a dielectric ceramic layer so as to form a plurality of capacitances. Internal electrodes 23 and 24 are formed. An external electrode 25 is formed on one end face of the element body 22 so as to be electrically connected to the internal electrode 23. On the other hand, an external electrode 26 is formed on the other end surface of the element body 22 so as to be electrically connected to the internal electrode 24.

  A method for manufacturing the multilayer ceramic capacitor 21 will be described with reference to FIG.

  First, after the internal electrode pattern 27 is printed on the ceramic green sheet 28 using a conductive paste containing Ni as a main component, a plurality of capacitances are configured to face each other as shown in a lamination diagram 31. Further, 100 layers of the dummy ceramic green sheets 29 and 30 on which the internal electrode pattern 27 was not printed on the upper and lower surfaces of the 100 layers were stacked and thermocompression bonded to obtain a pressed body. The thickness of the obtained crimped body was 1.2 mm. A molded body having a length of 4 mm, a width of 2 mm, and a thickness of 1.2 mm was cut out from the crimped body according to the internal electrode pattern 27.

The molded body was held in the atmosphere at 240 ° C. for 3 hours to remove the binder, and then using a mixed gas of N ₂ —H ₂ —H ₂ O, 1250 ° C. in a reducing atmosphere in which the Ni internal electrode was not oxidized, The element body 22 was obtained by holding for 2 hours and firing. The dielectric thickness after sintering was 7 μm.

  A conductive paste containing Cu as a main component is applied to both end faces of the obtained element body 22, dried at 120 ° C. for 10 minutes, and then baked at 900 ° C. in an atmosphere with an oxygen concentration of 10 ppm. , 26 were formed to obtain a multilayer ceramic capacitor as shown in FIG.

  As a result of applying a signal voltage of 1 kHz and 0.5 Vrms to the obtained multilayer ceramic capacitor and measuring a short-circuit occurrence rate, it was as low as 0.3%, reflecting that the smoothness and strength of the green sheet were good. It was found that a multilayer ceramic capacitor having excellent characteristics was obtained.

  In addition, the efficiency of crushing and dispersion | distribution can be raised further by cooling the rough dispersion liquid before a high pressure dispersion process previously.

  The present invention is not limited to the raw materials of the above-described examples, and the present invention can be applied without any problem as long as it is a ceramic raw material powder, an organic solvent, a binder, and a dispersant that are usually used in producing a ceramic slurry. can do.

  In the slurry manufacturing apparatus of FIG. 1, the number of back pressure load portions is increased instead of the slurry cooler, and the first is 20 MPa from the upstream side, the second is 10 MPa, the third is 5 MPa, the fourth is 2 MPa, The first is set to 1 MPa, the sixth is 0.5 MPa, the seventh is 0.2 MPa, and the eighth is 0.1 MPa to suppress the generation of a gas phase due to cavitation or bubbling. When the characteristics of the slurry, ceramic green sheet, and multilayer ceramic capacitor produced in the same manner as in Example 1 were measured, it was confirmed that the same effect as in Example 1 was obtained.

  The slurry after the high-pressure dispersion treatment is cooled to about 20 ° C. by injecting the cooled toluene directly into the dispersion section using the slurry production apparatus of FIG. 7, and further the first back pressure load from the dispersion section and the upstream side The slurry discharged from the dispersion part was cooled to about 10 ° C. by a slurry cooler disposed between the parts. When other characteristics of the slurry, ceramic green sheet, and multilayer ceramic capacitor manufactured in the same manner as in Example 1 were measured, it was confirmed that the same effects as in Example 1 were obtained.

  In addition, the efficiency of crushing and dispersion | distribution can be raised further by cooling the rough dispersion liquid before a high pressure dispersion process previously.

  In the slurry production apparatus of FIG. 7, the number of back pressure load portions is increased instead of the slurry cooler, and the first is 20 MPa from the upstream side, the second is 8 MPa, the third is 3 MPa, the fourth is 1.5 MPa. 5th, 0.5MPa, 6th, 0.2MPa, and 7th, 0.1MPa, and the other slurry manufactured in the same manner as in Example 1, the ceramic green sheet, and When the characteristics of the multilayer ceramic capacitor were measured, it was confirmed that the same effect as in Example 1 was obtained.

  In the slurry production apparatus of FIG. 7, the slurry after the high-pressure dispersion treatment is cooled to about 0 ° C. by directly injecting the cooled toluene into the dispersion portion except for the slurry cooler and the back pressure load portion. The generation of gas phase due to cavitation or bubbling was suppressed, and the characteristics of the slurry, ceramic green sheet, and multilayer ceramic capacitor manufactured in the same manner as in Example 1 were measured. It was confirmed that the effect of was obtained.

  45 parts by weight of α-terpineol was premixed with a mixer with respect to 50 parts by weight of metal Ni powder having an average particle size of 0.3 μm as the conductive powder to prepare a coarse dispersion.

  Next, by using the slurry production apparatus shown in the conceptual diagram of FIG. 1 described above, by applying a pressure of 200 MPa in the pressurizing unit and passing through a dispersion part made of a dispersion part orifice made of diamond having a diameter of 0.1 mm, A high-speed fluid jet was slurried.

  In addition, the slurry cooler disposed between the dispersion section and the first back pressure load section from the upstream side cools the slurry whose temperature has been increased to about 80 ° C. by high-pressure dispersion processing until it reaches about 10 ° C. did.

  In addition, the back pressure load part is 20 MPa at the first from the upstream side, 5 MPa at the second, 1.5 MPa at the third, 0.5 MPa at the fourth, 0.2 MPa at the fifth, and 0.1 MPa at the sixth. Was set to be. At that time, the back pressure load portion having the shape shown in FIG. 3 was used for the first to third portions, and the back pressure load portion having the shape shown in FIG. 4 was used for the fourth to sixth portions.

  Further, in order to investigate the change in dispersibility improvement due to the number of treatments, this high-pressure dispersion treatment was performed 1, 3, and 5 times, respectively, and three types of metal slurries with different treatment times were obtained.

  The dispersibility of the metal slurry thus obtained was measured using a particle size distribution measuring device manufactured by Microtrac, using the integrated 50% particle size (D50) of the particle size distribution as an index. Results were obtained.

  As shown in Table 2, even in one high-pressure dispersion treatment, the aggregate structure of the metal powder is crushed and the dispersibility can be improved. In addition, it can be seen that as the number of treatments is increased, the value of D50 becomes smaller, and the crushing and dispersion are more advanced.

  Next, 30 parts by weight of an organic vehicle in which α-terpineol and ethyl cellulose, which is a binder component, are premixed at a ratio of 5: 1 are added to the metal slurry of each treatment number, and stirred with a high-speed stirrer. Thus, a conductive paste having a pigment content of 40% was obtained by the production method according to the present invention.

  Further, to 50 parts by weight of metal Ni powder having an average particle size of 0.3 μm, 45 parts by weight of α-terpineol and 30 parts by weight of the above-described organic vehicle are added, premixed with a mixer, and then dispersed with three rolls. A conductive paste was obtained as a comparative example.

  Each of the conductive pastes thus obtained was screen-printed on a glass plate, and the surface roughness RzJIS (10-point average roughness described in JIS B 0601) of the obtained conductive paste coating film was contact type. When measured with a surface roughness meter, the results shown in Table 3 were obtained.

  As shown in Table 3, surface roughness can be improved by producing a conductive paste by high-pressure dispersion treatment as compared with a conventional production method. It can also be seen that the surface roughness is improved as the number of treatments is increased.

  Next, in the above-described Example of the present invention, a multilayer ceramic capacitor manufactured in the same manner as in Example 1 above was obtained using a conductive paste with a high-pressure dispersion treatment of 3 times. Moreover, the multilayer ceramic capacitor using the electrically conductive paste manufactured by the above-mentioned three rolls was also obtained as a comparative example. The coating thickness of the internal electrode pattern printed using each conductive paste was 2.0 μm.

  A signal voltage of 1 kHz and 0.5 Vrms was applied to the obtained multilayer ceramic capacitor, and the capacitance was measured. The number of measurements was 100. The capacitance variation 3 CV (%) was calculated from the measurement results, and the results shown in Table 4 were obtained.

  As shown in Table 4, by producing a conductive paste by high-pressure dispersion treatment, variation in capacitance can be improved as compared with a conventional production method.

  In this embodiment, α-terpineol, which is a terpene solvent, is used as a solvent for premixing, but another solvent that is a main solvent of the conductive paste, for example, a glycol solvent may be used. . In addition, you may add solvents, such as a ketone solvent, an alcohol solvent, and an aromatic solvent, for viscosity adjustment.

  In this embodiment, the high-pressure dispersion treatment is performed on the coarse dispersion obtained by mixing only the metal powder and the main solvent. However, the organic vehicle may be added in advance to perform the high-pressure dispersion treatment. As the binder component of the organic vehicle, cellulose resins such as methyl cellulose, ethyl cellulose, and nitrocellulose, acrylic resins, alkyd resins, phenol resins, and the like can be used.

  In addition, an additive component such as a dispersant or a surfactant for increasing the efficiency of the high-pressure dispersion treatment may be added in advance to the coarse dispersion. As the dispersing agent or surfactant, anionic, cationic, nonionic, and high molecular weight surfactants can be used.

  In addition, the above-mentioned organic components are effective for increasing the efficiency of the high-pressure dispersion treatment, but on the other hand, it is inappropriate to include them in the conductive paste, such as dissolving the binder contained in the ceramic green sheet during printing. The organic component considered to be may be removed after the high-pressure dispersion treatment.

  Similarly, when the amount of solvent in the coarse dispersion is large, it may be removed to an appropriate amount after the high-pressure dispersion treatment.

  The type of conductive powder is not particularly limited, and metal or alloy powder generally used in conductive paste, such as Ag-Pd, Ni, Cu, or oxide such as CuO is used. be able to. As for the particle size of the conductive powder, the present invention can be applied without any problem as long as it is within the range of the conductive powder usually used in the conductive paste. The effect of the present invention is most expected when applied to conductive powder having an average particle size of 1 μm or less determined by observation with an electron microscope, which is considered to be difficult to disintegrate by this dispersion method.

  The types and mixing ratios of solvents, binders, dispersants, surfactants, and the like for the conductive powder as described above can be usually determined empirically while considering the efficiency of crushing and dispersion.

It is a conceptual diagram of the manufacturing apparatus which shows the slurry manufacturing method of this invention. It is sectional drawing which shows the structure of the dispersion | distribution part of FIG. It is sectional drawing which shows the structure of the back pressure load part which loads back pressure by the orifice of FIG. It is sectional drawing which shows the structure of the other back pressure load part which loads back pressure by the flow path of FIG. It is sectional drawing of the laminated ceramic capacitor manufactured using the slurry which concerns on this invention. It is a conceptual diagram which shows the manufacturing method of a multilayer ceramic capacitor. It is a conceptual diagram of the manufacturing apparatus which shows the manufacturing method of the slurry by other embodiment of this invention. It is sectional drawing which shows the structure of the dispersion | distribution part which inject | pours a refrigerant | coolant directly of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Input tank 2 Pressurization part 3 Dispersion part 4 Back pressure load part 5 Discharge tank 6 Slurry cooler 7 Input line 8 Dispersion part supply line 9 Cooling part supply line 10 Discharge line 11 Reinjection line 12 Dispersion part orifice 13 Jet space part 14 Back pressure load part orifice 15 Back pressure load part flow path 16 Refrigerant charging part 17 Refrigerant pressurizing part 18 Refrigerant cooler 19 Refrigerant injection part

Claims (6)

In a slurry manufacturing method in which a dispersion treatment is performed by applying a high pressure to a coarse dispersion liquid prepared by premixing raw material powder and a dispersion medium and flowing at high speed,
A method for producing a slurry, wherein a back pressure is applied to the dispersion section, and the back pressure is applied stepwise on the downstream side of the dispersion section to lower the slurry pressure.   The method for producing a slurry according to claim 1, wherein the slurry is cooled in the dispersion portion.   The method for producing a slurry according to claim 1 or 2, wherein the slurry is cooled before the slurry pressure is lowered on the downstream side of the dispersion portion. In a slurry manufacturing method in which a dispersion treatment is performed by applying a high pressure to a coarse dispersion liquid prepared by premixing raw material powder and a dispersion medium and flowing at high speed,
The slurry is cooled in the dispersion part.   A molded body of the slurry obtained by the slurry production method according to any one of claims 1 to 4, comprising a ceramic raw material powder having an average particle diameter of 0.01 to 1 µm as a raw material powder, and a sheet thickness Is a ceramic green sheet, characterized by being 0.1 to 10 μm.   A slurry obtained by the slurry production method according to any one of claims 1 to 4, wherein the conductive slurry contains a conductive powder having an average particle size of 0.01 to 1 µm as a raw material powder. A conductive paste characterized by adding an organic vehicle.

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