JP2008169050A - Ceramic green sheet and manufacturing method thereof - Google Patents

Abstract

A ceramic green sheet and a method for manufacturing the same are provided.
In a method for producing a ceramic green sheet using a ceramic slurry containing at least an organic binder, a solvent, a surfactant / or dispersant, and a raw material ceramic, an aqueous solvent is used as the solvent, and the raw material ceramic is used. A method for producing a ceramic green sheet, characterized in that a homogeneous dispersed slurry produced using raw ceramics up to 100 nm even if the average particle size is large is tape-molded and dried to form a tape-molded body, and the ceramic green sheet And ceramic sheet members.
[Effect] A high-quality ceramic green sheet and member using nano-sized ceramic powder as a raw material can be provided.
[Selection] Figure 1

Description

  The present invention relates to a ceramic green sheet and a method for producing the same, and more particularly, a ceramic green sheet containing at least an organic binder, a solvent, a surfactant / or dispersant, and a raw ceramic powder, Is a water-based ceramic green sheet characterized in that the raw material ceramic has an average particle size of 100 nm or less, and a method for producing a sheet molded body capable of efficiently producing the ceramic green sheet. .

  Inorganic materials such as ceramics and metals are superior in mechanical strength and durability compared to organic materials such as plastics, and are therefore used in various applications such as structural materials and electrical / electronic materials. And these inorganic materials are generally used as a molded object (inorganic material molded object) formed in the shape suitable for each use.

  As a method for producing such an inorganic material molded body, the prior art document includes, for example, mixing and kneading aggregate particles (ceramic powder, etc.), dispersion medium (water, etc.), organic binder, etc. A method for producing an inorganic material molded body (high temperature sintering method) is disclosed in which a ceramic sintered body is obtained by molding the kneaded clay by a method such as extrusion molding, drying, and firing (for example, Patent Document 1).

  Also, aggregate particles (ceramic powder, etc.), dispersion medium (water, etc.), organic binder, etc. are mixed to obtain a slurry (slip), and the slurry is poured into a water-absorbing mold composed of a porous body, A manufacturing method (a cast molding method (slip casting method)) for obtaining an inorganic material molded body by drying and solidifying a slurry and then degreasing is disclosed (for example, see Non-Patent Document 1).

  In addition, aggregate particles (ceramic powder, etc.), dispersion medium (water, etc.), organic binder, etc. are mixed to obtain a slurry (slip), the slurry is thinly spread on a carrier film, and the slurry is dried and solidified. Thereafter, a production method (sheet molding method (doctor blade method), drying method) for obtaining an inorganic material molded body is disclosed (see Non-Patent Document 2, Patent Document 2-4, and Patent Document 5-6).

  The sheet molding method is a method for continuously obtaining a thin molded body composed of ceramic powder and an organic component (sheet molding method (doctor blade method)), for example, a ceramic substrate for electronic equipment, a ceramic package for LSI, a multilayer ceramic. Widely used for circuit boards, ceramic capacitors, and the like (see, for example, Non-Patent Document 2).

  In recent years, with the development of the IT industry, electronic devices have been downsized, and as a result, there has been a demand for homogenization and thinning of ceramic substrate materials. In order to meet these demands, it is necessary to refine and homogenize the ceramic powder, which is the main raw material used in forming the ceramic sheet. However, the miniaturization of ceramic powder has caused a problem of causing aggregation between particles and a decrease in filling property with an increase in surface area.

  In the case of a wet molding method such as sheet molding, as described above, a ceramic material molded body is obtained by molding and solidifying a slurry obtained by mixing a ceramic raw material with a dispersion medium, an organic binder, etc. by various methods. Chemistry makes this slurry preparation very difficult.

  When a concentrated slurry using a ceramic powder of 1 μm or less as a raw material is prepared by a conventionally used slurry preparation method such as a ball mill, it is possible to produce a good highly dispersible concentrated slurry due to particle aggregation. It was difficult, and defects such as uneven density and non-uniform structure occurred in the formed ceramic green sheet.

  Furthermore, media abrasion powder is mixed into the material as impurities due to collision between the media. The amount of incorporation is as high as 1 wt%, and such impurities interfere with sintering and cause deterioration of the properties of the product obtained. Conventional slurry preparation methods mainly use this medium pulverization type, but there are other preparation methods such as a stirring type, a powder type, and an ultrasonic type.

  However, in any of the methods, damage to the raw material powder surface or re-aggregation due to excessive energy is an unavoidable problem, and not a few impurities are mixed. Furthermore, all the conventional slurry preparation methods have problems in terms of economy and environment, such as requiring several hours to several days for the treatment.

  On the other hand, regarding the wet jet mill process employed in the present invention, there have been some reports so far, but the application field is mainly related to food (for example, see Patent Document 7). In addition, there are examples applied to ceramic powder, metal powder, and the like (see, for example, Patent Document 8), but all of them are focused on refining the raw material powder. In fact, no consideration is given to the molding method using the slurry produced by the above, the molded body, and the sintered body.

  At present, by dispersing ceramic powder in an organic solvent, a slurry with relatively high dispersibility is obtained up to particles of about 100 nm, and ceramic green sheets are being produced. However, organic solvents have high volatility and leave room for improvement in consideration of the work environment such as effects on the human body. However, the use of water as a solvent is problematic because of the large surface tension, defects such as cracks and warpage occur depending on the drying conditions.

  When manufacturing ceramic green sheets, if water can be used as a dispersion medium for ceramic particles instead of organic solvent, consideration for the harmfulness to human body and explosiveness caused by organic solvent is very important in the manufacturing process. Since less is required, it can be considered to be a safer manufacturing process.

  As described above, at present, a method for producing a good highly dispersible concentrated slurry while using water as a solvent using fine nano-sized ceramic powder of 100 nm or less as a raw material, and using the slurry A manufactured ceramic green sheet of good quality with few defects such as density unevenness, warpage, and non-uniform structure, and a manufacturing method thereof have not been disclosed yet, and a manufacturing method and a product of such a ceramic green sheet are not disclosed. Creation is eagerly desired by the industry.

Japanese Patent No. 227039 JP-A-5-319893 JP 7-315940 A JP-A-8-118329 JP-A-5-329816 JP 7-294122 A Japanese Patent Laid-Open No. 11-113544 JP-A-11-147714 Edited by the Ceramic Society of Japan, Ceramics Engineering Handbook, 2nd edition, Gihodo Publishing, 2002, p. 176-178 Edited by the Ceramic Society of Japan, Ceramics Engineering Handbook, 2nd edition, Gihodo Publishing, 2002, p. 187-189

  Under such circumstances, in view of the above prior art, the present inventors can use nano-sized ceramic powder as a raw material and produce a good highly dispersible concentrated slurry without using an organic solvent. As a result of intensive research aimed at developing new ceramic sheet manufacturing methods and ceramic sheet products that are possible, slurry preparation is performed from at least organic binder, solvent, surfactant / dispersant, and raw ceramic powder. It has been found that the intended purpose can be achieved by using a specific slurry, and the present invention has been completed.

  The present invention has been made in order to solve the above-described problems of the prior art, and uses a fine nano-sized ceramic powder of 100 nm or less as a raw material, while using water as a solvent, and has good high dispersibility. It is an object of the present invention to provide a method for producing a concentrated slurry, a ceramic green sheet having a good quality with less defects such as density unevenness, warpage, and non-uniform structure, and a method for producing the same, produced using the slurry. To do.

The present invention for solving the above-described problems comprises the following technical means.
(1) In a method for producing a ceramic green sheet using a ceramic slurry containing at least an organic binder, a solvent, a surfactant / or dispersant, and a raw material ceramic, an aqueous solvent is used as the solvent, and the raw material ceramic A method for producing a ceramic green sheet, characterized in that a homogeneous dispersed slurry produced using a raw material ceramic having a mean particle size of up to 100 nm is tape-molded and dried to obtain a tape-molded body.
(2) The ceramic green sheet according to (1), wherein in the tape molded body, the ceramic powder having an average particle size of up to 100 nm is aggregated to 0.5 to 10 μm. Production method.
(3) The method for producing a ceramic green sheet according to (1) or (2) above, wherein a filling rate of the ceramic powder after drying is 30% or more.
(4) The method for producing a ceramic green sheet according to any one of (1) to (3), wherein the thickness of the sheet is 1 mm at most.
(5) In order to obtain a good dispersion state of the ceramic particles, a homogeneous dispersion slurry that stably maintains the dispersion state is prepared by crushing using a jet mill. Ceramic green sheet manufacturing method.
(6) The method for producing a ceramic green sheet according to (5), wherein the concentration of the raw material powder contained in the slurry is in the range of 10 to 60 vol%.
(7) A slurry having a viscosity of 40 mPa · s at most and a change amount of viscosity per unit time of 10 mPa · s / h at most is prepared. Manufacturing method of ceramic green sheet.
(8) The method for producing a ceramic green sheet according to (5) above, wherein the treatment pressure by the wet jet mill is higher than 10 MPa.
(9) The tape-like sheet molded body is produced by drying using a microwave in a short time in a dry state equivalent to natural drying. Ceramic green sheet manufacturing method.
(10) A ceramic green sheet using fine nano-sized ceramic powder as a raw material, 1) up to 100 nm even if the average particle size of the ceramic powder is large, 2) 0.5 to 10 μm of ceramic powder 3) Filling ratio of the ceramic powder after drying is at least 30%, 4) Even if the thickness of the sheet is thick, it is up to 1 mm, and 5) At least an organic binder, a surfactant / or 6) A ceramic green sheet characterized by containing a dispersant and having no uniform warp and non-uniform structure and a uniform density.
(11) A ceramic sheet member comprising the ceramic green sheet according to (10) and having a quantum size effect of a raw material powder.

Next, the present invention will be described in more detail.
The present invention relates to a method for producing a ceramic green sheet using a ceramic slurry containing at least an organic binder, a solvent, a surfactant / dispersant, and a raw ceramic, and using the aqueous ceramic as a solvent, the raw ceramic As described above, even if the average particle size is large, a homogeneous dispersion slurry prepared using raw ceramics up to 100 nm is tape-molded and dried to form a tape-molded body. The present invention also relates to a ceramic green sheet using fine nano-sized ceramic powder as a raw material, and the ceramic powder has an average particle size of at most 100 nm, and the ceramic powder has a thickness of 0.5 to 10 μm. It is agglomerated, the filling rate of the ceramic powder after drying is at least 30%, the sheet thickness is up to 1 mm, and contains at least an organic binder, surfactant / dispersant It has no uniform warp and non-uniform structure, and has a uniform density. Furthermore, the present invention is a ceramic sheet member made of the above ceramic green sheet, characterized by having a quantum size effect of the raw material powder.

  Next, the production of the slurry will be described. The present invention is a method of preparing a slurry having a mixing and crushing process by a wet jet mill, and after the mixing and crushing process by a wet jet mill, the surface structure is not damaged and is pulverized to primary particles. In addition, as the wet jet mill treatment step, the slurry is pumped at a high pressure to a nozzle disposed in a sealed state in a pressure vessel, and the opposing flows of the slurry collide and merge with each other Is used to produce a slurry.

  In the present invention, a wet jet mill is used to produce a slurry having a viscosity of 40 mPa · s or less and a change in viscosity per unit time of 10 mPa · s / h or less. The wet jet mill does not use a pulverization medium, and the processing solution is made to flow at high speed by an arbitrary method, and the turbulent flow, shear flow, A type that effectively utilizes the cavitation effect and mixes, disperses, and disintegrates the object to be processed in the processing solution is preferably used.

  In order to more effectively exhibit the effects of mixing, dispersion, and crushing by such a wet jet mill, a preferable treatment pressure is about 10 MPa or more, more preferably about 50 MPa or more, and further preferably about 100 MPa or more. In this wet jet mill process, the number of treatments is not particularly limited, and the treatment can be repeated many times until a slurry having desired characteristics is obtained. Usually, the treatment is performed 1 to 10 times. Is called.

  As described above, the wet jet mill used in the present invention generates a high-speed flow by an arbitrary method, causes collision between liquids or a liquid and a channel wall, and turbulent flow and shear generated by the high-speed flow. In addition, it is a collective term for apparatuses having a function of effectively emulsifying, dispersing, and mixing by effectively utilizing the cavitation effect and the like to atomize the object to be processed.

  As such a wet jet mill, there is a high-pressure homogenizer. Specifically, a liquid to be treated is sprayed from a nozzle by a plunger pump, a rotary pump, or the like and collides with a fixed plate at a high speed, and a target to be sprayed is used. There is a method of causing treatment liquids to collide with each other. When the liquid to be treated passes through the flow path at high speed or while colliding, the dispersoid contained in the fluid to be treated is subjected to turbulent flow and shearing and is crushed and immediately after the collision. When released under reduced pressure, a cavitation effect occurs, and the dispersoid in the liquid to be treated is remarkably atomized due to an impact caused by sudden pressure release.

  As the above-mentioned wet jet mill, preferably, for example, a type using a high-speed jet by a valve plate, commercially available as a “high-pressure homogenizer”, a type that collides at high speed in a slit-shaped flow path, 90 ° A type that causes high-speed collisions within each single-character flow path that communicates in phase, a type that generates multiple collisions between fluids in the same nozzle, and a collision that occurs by jetting from a facing orifice to an aspherical structure room Or a type in which a liquid jet flow collides at high speed.

  These wet jet mills have some differences in mixing, dispersion, and crushing effects due to the characteristics of each device type. However, the above-mentioned wet jet mills use dispersion devices such as the conventional media-media type dispersers as described above. Compared with the case where it was, the stable slurry can be obtained with remarkably high efficiency. Therefore, the type of the wet jet mill used in the present invention is not particularly limited, but the method of causing high-speed slurry to collide from the front is desirably the most desirable.

  As described above, the present invention employs a slurry preparation method that does not use a pulverizing medium such as a medium, thereby containing particles pulverized to a primary particle size or close to the primary particle size, and having low viscosity and low re-use. A slurry having cohesiveness is produced. The slurry of the present invention contains a powder having the original crystallinity and surface structure that is crushed into primary particles and the surface state before dispersion is not broken. Based on these properties, a slurry suitable for tape molding is formed that has low viscosity and does not exhibit re-agglomeration.

  The slurry of the present invention preferably has a viscosity of 40 mPa · s or less and a change in viscosity per unit time of 10 mPa · s / h or less. When the viscosity of the slurry is 40 mPa · s or more, it is not preferable because the rearrangement of particles at the time of casting is hindered and the relative density of the molded body is lowered. In addition, when the amount of change in viscosity per unit time is 10 mPa · s / h or more, the reaggregation property is increased and the relative density of the molded body is lowered, which is not preferable.

  The slurry of the present invention is preferably produced by wet jet milling, in which the particles are crushed to primary particles and the original crystallinity is maintained without breaking the surface state prior to dispersion. In addition, since the surface state is preserved, it exhibits good viscosity characteristics. On the other hand, in a slurry manufacturing method using a grinding medium such as a medium, for example, a slurry manufactured by a grinding / dispersing process using a ball mill, the viscosity rapidly increases immediately after the manufacturing. Such an increase in viscosity is caused by the re-aggregation of the powder due to the damage of the crystallinity and surface structure of the raw material powder due to the collision of the medium having a large weight and the increase of the surface energy.

  The suitable density | concentration of the raw material powder contained in a slurry is the range of 10-60 vol%. If it is 10 vol% or less, the shrinkage at the time of sheet molding is large, and if it is 60 vol% or more, a slurry having fluidity capable of wet jet milling cannot be produced, which is not preferable. Preferably, a slurry containing the raw material powder in the range of 10 to 50 vol% is used. The slurry may contain various additives other than the ceramic powder, the solvent, and the organic binder as long as the effects of the present invention are not impaired. Examples of the additive include polyethylene glycol, polyether, ammonium carbonate, polycarboxylate, polyacrylate and the like. Polyethylene glycol has the effect of improving the fluidity of the slurry as a plasticizer. Polyether is used as an antifoaming agent, and ammonium carbonate is used as a drying aid to remove pores in the slurry and molded body. Polycarboxylic acid salts and polyacrylic acid salts have the effect of modifying the affinity between powder and water as a dispersing agent and dispersing them uniformly with the powder.

  The average particle diameter of the “ceramic powder” is preferably in the range of 1 nm to 50 μm, and more preferably in the range of 1 nm to 1 μm. The solvent is preferably an aqueous solvent, and conventionally used solvents such as alcohols, ketones, oils, and amines can be used as they are in the present invention. From the viewpoint of environmental load, distilled water, ion exchange water, tap water, industrial water, etc. are used as the aqueous solvent.

  Next, the production of ceramic green sheets will be described. Examples of the ceramics targeted in the present invention include oxides, nitrides, carbides, specifically, oxide ceramics such as zinc oxide and alumina, and nitrides. Non-oxide ceramics such as silicon and other appropriate ceramics are exemplified. The present invention can be applied to molding of all ceramics regardless of the type of ceramics. In addition, a normal method can be adopted as a method for producing a green sheet, and the above-described specific ceramic slurry is used as a raw material slurry. There is no particular limitation. Examples of green sheet production include a doctor blade method, a calendar method, and a paper dipping method. Of these, the doctor blade method can be preferably used.

  Next, although the produced green sheet is dried, it is preferable to use a microwave as a technique for drying the ceramic green sheet in a short time. The microwave used in the present invention is irradiated with a microwave with a frequency of 300 MHz to 30 GHz for 1 second to 10 hours, preferably with a microwave with a frequency of 2450 MHz for 1 second to 1 hour. In the case of microwaves, when the governments of each country have determined frequencies that can be used industrially, it is necessary to select the frequencies to be used in accordance with the frequencies.

  Currently, in Japan, frequencies of 433.92 MHz, 2450 MHz, 5800 MHz, and 24.125 GHz can be used, and an appropriate frequency may be appropriately selected from these frequencies. In other countries, frequencies other than these frequencies, for example, 915 MHz (US), 896 MHz (UK), 2375 MHz (Eastern Europe, Russia) may be used.

  The ceramic green sheet of the present invention and the method for producing the same have been specifically described above. The present invention uses a fine nano-sized ceramic powder of 100 nm or less as a raw material, and uses water as a solvent, while maintaining good high dispersion. Method for producing a high-density slurry, and a ceramic green sheet based on the technical idea of producing a good quality ceramic green sheet with less defects such as density unevenness, warpage, and non-uniform structure using the slurry, and its production Widely encompasses the method.

  The present invention provides a tape-forming dispersion medium that is extremely fluid and easy to relieve strain by producing a homogeneous dispersion slurry regardless of solvent by dispersing ceramic nano-sized particles with a jet mill. And producing a very uniform and thin tape molded article by irradiating the obtained tape molded article with microwaves to produce a dry state similar to natural drying in a short period of time. It greatly contributes to the creation of new materials, energy saving and shortening of process time in the ceramic manufacturing process.

The present invention has the following effects.
(1) According to the present invention, it is possible to provide a method for producing a good highly dispersible concentrated slurry using fine nano-sized ceramic powder of 100 nm or less as a raw material and using water as a solvent.
(2) Using the slurry, it is possible to obtain a ceramic green sheet of good quality with few defects such as density unevenness, warpage and non-uniform structure.
(3) The ceramic green sheet manufacturing method of the present invention can use an aqueous solvent in the slurry preparation process, and builds a safer manufacturing process than the conventional method using an organic solvent. It becomes possible to do.
(4) The ceramic green sheet of the present invention also has a very high specific surface area of the molded body. Therefore, the high specific surface area of the molded body, such as the photocatalytic effect, light scattering effect, and nanostructure effect, the quantum size effect of the raw material powder Therefore, it is also suitably used as a sheet molded body that can be expected to improve performance and develop various functions.
(5) The ceramic green sheet of the present invention is suitably used as a ceramic green sheet molded body used in various applications such as a ceramic substrate for electronic equipment, a ceramic package for LSI, a multilayer ceramic circuit substrate, and a ceramic capacitor. .
(6) By applying microwave irradiation to the drying of the green sheet, it is possible to drastically reduce the time required for the drying process, which previously required a long time, together with the effect of improving the quality. The process can be replaced with one that saves energy and shortens the process time.

  EXAMPLES Next, although this invention is demonstrated concretely based on an Example, this invention is not limited at all by the following Examples.

As ceramic materials, high-purity alumina powder (Nano Tek, manufactured by CI Kasei Co., Ltd., average particle diameter (ultrasonic attenuation spectroscopy): 43 nm, true density: 3.6 g / cm ³ ), 50 g of distilled water and polyacrylic 4 g of ammonium acid (A-6114, manufactured by Toa Gosei Co., Ltd.) was added and mixed. The obtained slurry was subjected to wet jet mill treatment, whereby the aggregation of alumina powder in the slurry was crushed and dispersed.

(Comparative Example 1)
As ceramic materials, high-purity alumina powder (Nano Tek, manufactured by CI Kasei Co., Ltd., average particle diameter (ultrasonic attenuation spectroscopy): 43 nm, true density: 3.6 g / cm ³ ), 50 g of distilled water and polyacrylic 4 g of ammonium acid (A-6114, manufactured by Toa Gosei Co., Ltd.) was added and mixed. The obtained slurry was ball milled to break up and disperse the aggregation of alumina powder in the slurry.

(Implementation result 1)
After the treatment shown in Example 1 and Comparative Example 1, the pulverization and dispersion of each slurry were evaluated by confirming the particle size by particle size distribution measurement.

  The particle size distribution of the slurry after the ball mill treatment and the jet mill treatment is shown in FIG. Since the same raw material is used, a sample with better dispersibility has a smaller integrated particle size and a single peak in frequency distribution. From FIG. 1A, the sample subjected to the dispersion treatment using a jet mill shows a smaller value at a 50% particle size. In addition, as shown in FIG. 1B, when a ball mill is used, there is a peak different from a peak at 0.05 μm between 0.1 μm and 0.5 μm, and there are aggregated particles. You can see that From this, it was confirmed that a slurry having higher dispersibility can be produced by dispersing using a jet mill.

  In a sample dispersed by wet jet mill treatment, 25 g of polyvinyl alcohol (MP Biomedical, average molecular weight 22,000) and 2 g of polyethylene glycol (Wako Pure Chemical Industries, average molecular weight 500), an antifoaming agent (Deformer 470). 0.0125 g) (manufactured by San Nopco Co.) was added and further mixed to obtain a paste. The obtained paste was applied on a carrier film to a width of 5 cm and a thickness of 1 mm, followed by natural drying.

(Comparative Example 2)
In a sample dispersed by ball milling, 25 g of polyvinyl alcohol (MP Biomedical, average molecular weight 22,000) and 2 g of polyethylene glycol (Wako Pure Chemical Industries, average molecular weight 500), an antifoaming agent (Deformer 470, Sannopco) (0.025 g) was added and further mixed to obtain a paste. The obtained paste was applied on a carrier film to a width of 5 cm and a thickness of 1 mm, followed by natural drying.

(Result 2)
After the treatment shown in Example 2 and Comparative Example 2, the appearance and microstructure of the obtained ceramic green sheet were observed and evaluated by visual observation and a scanning electron microscope (SEM).

  The SEM observation photograph of the ceramic green sheet produced using the dispersion method shown in Example 2 and Comparative Example 2 is shown in FIG. (A) is the sample which performed the ball mill process, (b) is the sample which performed the jet mill process. In the sample subjected to the ball mill treatment, as shown by the white arrow, not the particles but the lump of added organic matter is observed here and there. On the other hand, in the sample subjected to the jet mill treatment, such an organic lump is not recognized, and it can be seen that the particles are appropriately coated.

  FIG. 3 shows an external view photograph of the ceramic green sheet produced using the dispersion method shown in Example 2 and Comparative Example 2 after being air-dried. (A) is the sample which performed the ball mill process, (b) is the sample which performed the jet mill process. The sample subjected to the ball mill treatment warped up as shown in the photograph after drying. This is because the particles in the slurry are insufficiently disintegrated and the dispersibility is low, resulting in uneven density and non-uniform structure in the sample, resulting in defects after drying. On the other hand, the sample subjected to the jet mill treatment showed no warp even after drying and showed a good sheet shape. From these results, a more uniform green sheet could be produced by using a jet mill.

As ceramic materials, high-purity alumina powder (Nano Tek, manufactured by CI Kasei Co., Ltd., average particle diameter (ultrasonic attenuation spectroscopy): 43 nm, true density: 3.6 g / cm ³ ), 50 g of distilled water and polyacrylic 4 g of ammonium acid (A-6114, manufactured by Toa Gosei Co., Ltd.) was added and mixed. The obtained slurry was wet-jet milled to break up the aggregation of the alumina powder in the slurry and uniformly disperse it.

  Subsequently, 25 g of polyvinyl alcohol (MP Biomedical, average molecular weight 22,000) and 2 g of polyethylene glycol (Wako Pure Chemical Industries, average molecular weight 500), 0.0125 g of antifoaming agent (Deformer 470, San Nopco) Was added and further mixed to obtain a paste. At this time, the viscosity of the paste was about 1500 mPa · s.

  The obtained paste was applied on a carrier film to a width of 5 cm and a thickness of 1 mm, and then rapidly dried in a 2.45 GHz microwave drying oven at a drying temperature of 80 ° C. and a relative humidity of 40%.

(Comparative Example 3-1)
The paste shown in Example 3 was applied on a carrier film to a width of 5 cm and a thickness of 1 mm, followed by natural drying.

(Comparative Example 3-2)
The paste shown in Example 3 was applied on a carrier film to a width of 5 cm and a thickness of 1 mm, and rapid drying was performed in a constant temperature and humidity drying oven at a drying temperature of 80 ° C. and a relative humidity of 40%.

  The appearance of the ceramic green sheet obtained in Example 3 is shown in FIG. The green sheet was not cracked and had a good appearance. Moreover, the linear shrinkage ratio after drying was confirmed to be as high as 4% in the direction parallel to the carrier film and 85% in the direction perpendicular to the carrier film. Further, when the filling rate of the ceramic powder was estimated from the volume and weight of the green sheet after drying, it was about 55%.

  5 and 6 show SEM photographs of the green sheets obtained in Example 3, Comparative Example 3-1, and Comparative Example 3-2. FIG. 5 is a sample prepared without adding an antifoaming agent, and FIG. 6 is a sample using the antifoaming agent. From FIG. 5, it was found that the particles aggregated to about 2 μm were packed with high density by any drying method. However, since no antifoaming agent was used, there were innumerable pores that could be confirmed with the naked eye, and there were many cracks.

  On the other hand, when FIG. 6 which is a sample using an antifoaming agent was seen, in any drying method, it was found that particles aggregated at about 500 nm were packed with high density. In the sheet dried at 80 ° C. in a constant temperature and humidity drying furnace, many straight pores of about 10 μm were observed at the top of the sheet. These pores are considered to be formed as water passages when the sheet is dried. On the other hand, natural drying and microwave drying were good sheets with no cracks or pores.

  As described above in detail, the present invention relates to a ceramic green sheet and a method for producing the same, and according to the present invention, a highly highly dispersible sheet formed using a fine nano-sized ceramic powder of 100 nm or less. The body can be provided. The ceramic green sheet of the present invention is suitably used as a ceramic green sheet molded body in various applications such as a ceramic substrate for electronic equipment, a ceramic package for LSI, a multilayer ceramic circuit substrate, a ceramic capacitor, and the like.

  Furthermore, since the ceramic green sheet of the present invention and the method for producing the same use a fine nano-sized ceramic powder of 100 nm or less, the specific surface area of the molded body is also very high, so that the photocatalytic effect and the light scattering effect, It is also suitably used as a sheet molded body that can be expected to improve performance and develop various functions due to the high specific surface area of the molded body, such as the nanostructure effect, and the quantum size effect of the raw material powder.

It is a figure which shows the particle size distribution of the alumina particle after crushing and dispersion | distribution by a ball mill process and a wet jet mill process. It is a figure which shows the SEM observation photograph of the ceramic green sheet produced by the ball mill process and the wet jet mill process. (A) Ball mill treatment, (b) Wet jet mill treatment. It is a figure which shows the external appearance photograph of the ceramic green sheet produced by the ball mill process and the wet jet mill process. (A) Ball mill treatment, (b) Wet jet mill treatment. It is a figure which shows the surface external appearance photograph of the ceramic green sheet after drying. (A) No antifoaming agent, (b) With antifoaming agent. It is a figure which shows the SEM photograph of the ceramic green sheet after drying (no antifoamer addition). It is a figure which shows the SEM photograph of the ceramic green sheet after drying (antifoamer addition).

Claims (11)

  In a method for producing a ceramic green sheet using a ceramic slurry containing at least an organic binder, a solvent, a surfactant / or dispersant, and a raw material ceramic, an aqueous solvent is used as the solvent, and the average particle size is used as the raw material ceramic. A method for producing a ceramic green sheet, characterized in that a homogeneous dispersion slurry produced using a raw material ceramic of up to 100 nm is tape-molded and dried to form a tape-molded body even if the size is large.   2. The method for producing a ceramic green sheet according to claim 1, wherein in the tape molded body, ceramic powders having a mean particle size of up to 100 nm are aggregated to 0.5 to 10 μm.   The method for producing a ceramic green sheet according to claim 1 or 2, wherein a filling rate of the ceramic powder after drying is 30% or more.   The method for producing a ceramic green sheet according to any one of claims 1 to 3, wherein the thickness of the sheet is at most 1 mm.   2. The ceramic green sheet according to claim 1, wherein in order to obtain a good dispersion state of the ceramic particles, a homogeneous dispersion slurry that stably maintains the dispersion state is prepared by crushing using a jet mill. Manufacturing method.   The method for producing a ceramic green sheet according to claim 5, wherein the concentration of the raw material powder contained in the slurry is in the range of 10 to 60 vol%.   The ceramic green sheet according to claim 5, wherein a slurry having a viscosity of at most 40 mPa · s and a change in viscosity per unit time of at most 10 mPa · s / h is prepared. Production method.   The method for producing a ceramic green sheet according to claim 5, wherein the treatment pressure by the wet jet mill is higher than 10 MPa.   The ceramic green sheet according to claim 1, wherein a tape-shaped sheet molded body is produced by drying using a microwave in a short time in a dry state equivalent to natural drying. Manufacturing method.   A ceramic green sheet using fine nano-sized ceramic powder as a raw material, 1) up to 100 nm even if the average particle size of the ceramic powder is large, and 2) the ceramic powder aggregates from 0.5 to 10 μm. 3) Filling ratio of the ceramic powder after drying is at least 30%, 4) up to 1 mm even if the thickness of the sheet is thick, and 5) at least an organic binder, surfactant / dispersant. 6) A ceramic green sheet characterized by having no uniform warp and non-uniform structure and having a uniform density.   A ceramic sheet member comprising the ceramic green sheet according to claim 10 and having a quantum size effect of a raw material powder.