JP2004090466A - Method and apparatus for manufacturing ceramic green sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a ceramic green sheet which has a proper drying efficiency and in which a craze or the like is hardly formed, and an apparatus for the same. <P>SOLUTION: The method for manufacturing the ceramic green sheet includes a molding step of molding a slurry 4 containing a ceramic powder, a resin and a solvent in a sheet-like state to manufacture a molding 5, and a drying step of drying the molding 5. In the method, the drying step generates an air flow in an opposite direction to a moving direction of the molding 5 while the molding 5 is moved in a housing 21, gradually raising a temperature of the molding by directing the molding 5 toward its moving direction or holding the temperature constant, and gradually lowering a concentration of the solvent contained in the flow in the direction of moving the molding 5. The apparatus for manufacturing the sheet includes a molding means 1, a drying means 2 and a moving means 3 for realizing the method. <P>COPYRIGHT: (C)2004,JPO

Description

【００２７】
［３］実施例の効果
表１に示されるように、気流に含まれる溶剤濃度が第２ゾーンで最も高い場合（比較例）クラックの発生が顕著である。これにより、気流温度及び成形体温度を成形体が進む方向に徐々に高くしても溶剤濃度が第２ゾーンで最も高い場合、乾燥性能が良くないことが判る。
これに対し、この溶剤濃度を第１ゾーンで最も高くし、第３ゾーンで溶剤濃度が０体積％となるようにした場合（実施例１及び実施例２）、クラックの発生が抑制される。これにより、気流温度及び成形体温度を成形体が進むほう方向に徐々に高くし、気体に含まれる溶剤濃度を成形体が進むほう方向に徐々に小さくした場合、乾燥性能が優れていることが判る。
また、第１ゾーン及び第２ゾーンの気流におけるレイノルズ数を３３００及び１３０００とした場合（実施例１）、クラックの発生は確認されなかった。これにより、成形体が筐体の内部に入ってから上記気流中に含まれる上記溶剤の濃度が１体積％となるまでの間における上記気流のレイノルズ数を２００００以下である３３００とした場合、乾燥性能が極めて優れていることが判る。
更に、実施例１では、この加熱手段２３に循環させる温水の温度は気流の温度よりも高くなるように調整されている。また、この加熱手段２３の温度を第１ゾーンの前方のヒータ２３１よりも中央のヒータ２３２の方が高くなるように調製し更に、成形体５が移動する方向に向かって徐々に上昇するように調整されている。これにより、セラミックグリーンシートに膜が形成されない。従って、乾燥性能がより優れていることが判る。
【００２８】
尚、本発明においては、上記の具体的な実施例に記載されたものに限らず、目的及び用途に応じて、本発明の範囲内で種々変更した実施例とすることができる。
例えば、本実施例では、図２に示されるように、筐体２１としてゾーンに分けられたものを用いたが、図３に示されるように、ゾーンに分けられていないものを用いても良い。このとき、筐体２１に形状等は、前記説明製造装置の説明をそのまま適用できる。
また、本実施例では筐体内部のゾーンの数を３としたがこのゾーンの数は特に限定されず、２〜５個のゾーンにわけることができる。
更に、本実施例では、セラミック原料としてジルコニア粉末を使用したが、本発明ではこれに限定されず、例えば、アルミナ粉末等を使用しても同様の効果を得ることができる。
【図面の簡単な説明】
【図１】実施例のセラミックグリーンシートの製造装置の模式図である。
【図２】実施例の乾燥手段の内部構造を示す模式図である。
【図３】本発明における他の態様の乾燥手段の内部構造を示す模式図である。
【符号の説明】
１；成形手段、２；乾燥手段、２１；筐体、２１１；第１ゾーン、２１２；第２ゾーン、２１３；第３ゾーン、２１４；天井部、２２；気流発生手段、２２１；吸気手段、２２２；排気手段、２３；加熱手段、３；移動手段、４；泥漿、５；成形体、６；アニール手段。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for manufacturing a ceramic green sheet. More specifically, it is possible to dry in a short time a molded article obtained by molding a slurry containing a ceramic powder, a resin and a solvent into a sheet, and further, when this molded article is dried, a crack is formed on the ceramic green sheet. The present invention relates to a method and an apparatus for producing a ceramic green sheet in which irregularities hardly occur on the surface thereof. The ceramic green sheet manufactured according to the present invention is widely used for ceramic laminates such as ceramic sensors and ceramic heaters.
[0002]
[Prior art]
In the production of conventional ceramic green sheets, a slurry containing ceramic powder, resin and a solvent is formed into a sheet, and the formed body is heated by a heater or the like that circulates hot water from a hot water tank to the inside of a tube, At the same time, drying was performed by directly blowing warm air on the molded body, or by naturally drying the molded body.
[0003]
[Problems to be solved by the invention]
In ceramic green sheets used for functional ceramic elements or ceramic substrates such as ceramic heaters, high-purity ceramic materials are selected to improve product performance, and sintering aids are reduced as much as possible. The sintering temperature is high. However, on the other hand, in a ceramic green sheet used for a ceramic substrate such as a functional ceramic element or a ceramic heater, the sintering temperature is not desired to be increased because the firing must be performed simultaneously with the functional ceramic or the conductor. Therefore, as a method of improving the sinterability, a fine powder raw material having a large specific surface area is usually used. However, when a fine powder having a large specific surface area is used, it is necessary to increase the amount of resin according to the specific surface area. This is because the amount of resin is small and there is not enough resin on the surface of the ceramic powder, so that the bonding between the powders is weakened and cracks (cracks) are likely to occur in the ceramic green sheet. On the other hand, if the amount of resin is increased to prevent the occurrence of cracks, it is difficult to obtain the dimensional accuracy required as a product. This is because the shrinkage during sintering is large, and deformation tends to occur. In addition, the ceramic green sheet does not easily dry. This is because a surface film is easily formed.
Therefore, in order to prevent the occurrence of cracks and surface films, it is necessary to control advanced drying conditions of the green sheet, but there is a problem that it is difficult to control the drying conditions in conventional natural drying and the like.
Further, when the molded body is naturally dried, there is a problem that it takes time until the molded body is completely dried.
[0004]
The present invention has been made in order to solve the above problems, and has good drying efficiency, and further facilitates control of drying conditions, whereby ceramic green sheets are less likely to form cracks and surface films. It is an object to provide a sheet manufacturing method and a sheet manufacturing apparatus.
[0005]
[Means for Solving the Problems]
The method for producing a ceramic green sheet of the present invention is a molding step of molding a slurry containing ceramic powder, a resin, and a solvent into a sheet to produce a molded body, and then a drying step of drying the molded body, In the method for producing a ceramic green sheet having the above, the drying step generates an airflow in a direction opposite to a moving direction of the molded body while moving the molded body inside the housing, and a direction in which the molded body moves. , The temperature of the molded body is gradually increased or the temperature is kept constant, and the concentration of the solvent contained in the gas stream is gradually decreased in the direction in which the molded body moves.
Further, the inside of the housing is divided into a plurality of zones, and an independent airflow can be generated for each zone.
The flow rate of the airflow is smallest in the zone where the compact enters first, and can be gradually increased in the direction in which the compact moves in each zone.
The Reynolds number of the gas flow may be 20,000 or less at least until the concentration of the solvent contained in the gas constituting the gas flow becomes 1% by volume after the molded body enters the inside of the housing. it can.
The method for producing a ceramic green sheet according to the present invention comprises: a molding means for molding a slurry containing a ceramic powder, a resin and a solvent into a sheet to produce a molded body; a drying means for drying the molded body; Moving the body from the molding means to the drying means, further comprising a moving means for moving the inside of the drying means, the drying means, a housing in which the molded body moves inside by the moving means, An airflow generating means formed on the housing and flowing an airflow in a direction opposite to a direction in which the molded body moves above the molded body, and a heating means for heating the molded body from at least a lower part, The heating means heats the molded body so as to gradually increase or keep the temperature of the molded body constant, and the concentration of the solvent contained in the gas constituting the airflow generated by the airflow generation means is determined by the molding method. Body moves Characterized in that it is adjusted to be gradually lowered to the direction.
Further, the inside of the casing is divided into a plurality of independent zones, and the airflow generating means includes an intake means for taking gas into each of the zones and an exhaust gas for discharging the gas from each of the zones. Means, and the intake means and the exhaust means may be arranged above the molded body so that the air flow is generated in a direction opposite to a direction in which the molded body moves.
Further, the airflow generating means generates the airflow such that the flow velocity of the airflow in the zone where the compact enters first is the smallest, and the flow velocity gradually increases in the direction in which the compact moves in each zone. Things.
The airflow generating means may have a Reynolds number of 20,000 or less from at least the time when the molded body enters the inside of the housing until the concentration of the solvent contained in the gas constituting the airflow becomes 1% by volume. To generate the airflow.
[0006]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the manufacturing method and manufacturing apparatus of the ceramic green sheet of this invention, it can prevent effectively that the film | membrane is formed on the surface of a molded object by the resin contained in a molded object when drying a molded object. Thereby, the drying efficiency is good, and the formation of cracks and irregularities on the ceramic green sheet can be effectively prevented.
In addition, when the housing is divided into a plurality of independent zones, and when the airflow flows in each independent zone, the temperature, the flow velocity, and the like of the airflow can be adjusted at an arbitrary position inside the drying unit. Further, when the flow velocity of the airflow is set to be the smallest in the zone where the molded body enters first and gradually increased in the direction in which the molded body moves in each zone, a resin film is formed on the molded body. Can be further prevented. Thereby, the formation of cracks and irregularities in the ceramic green sheet can be more effectively prevented.
Further, when the Reynolds number of the gas flow is set to 20,000 or less until the concentration of the solvent contained in the gas flow becomes 1% by volume, the gas flow can be a laminar flow. Thereby, it is possible to further prevent the formation of the resin film on the molded body, and it is possible to more effectively prevent the ceramic green sheet from being cracked or uneven.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[1] Manufacturing method of ceramic green sheet
The present invention has a molding step of molding a slurry containing a ceramic powder, a resin, and a solvent into a sheet to produce a molded body.
The above “slurry” is a raw material of the ceramic green sheet, and contains ceramic powder, resin and solvent.
The “ceramic powder” is a ceramic material of a ceramic green sheet. The material of the ceramic powder includes, for example, alumina and zirconia, but is not particularly limited. Although the specific surface area of the ceramic powder is not particularly limited, it is 2.5 to 6 m. ² / G, preferably 3-5 m ² / G.
The “resin” functions as a binder. Examples of this resin include, but are not limited to, acrylic resins, butyral resins, and urethane resins. These may be used alone or in combination of two or more.
The "solvent" functions as a dispersion medium for the ceramic powder. Examples of this solvent include, but are not limited to, methyl ethyl ketone, toluene, and ethanol. These may be used alone or in combination of two or more.
[0008]
In addition, the slurry may further contain a plasticizer and a dispersant.
The plasticizer has a function of improving the processability of the green sheet. Examples of the plasticizer include, but are not limited to, dibutyl phthalate, 2-ethylhexyl phthalate, and 2-ethylhexyl adipate. These may be used alone or in combination of two or more.
The dispersant has a function of improving the dispersibility of the powder in the slurry. Examples of the dispersant include, but are not limited to, sorbitan monolaurate, polycarboxylate, nonionic activator, and anionic activator. These may be used alone or in combination of two or more.
[0009]
The method for producing a molded article from the slurry is not particularly limited, but a method of applying a slurry on a carrier film by a doctor blade method, a slip casting method or the like to produce a molded article in a sheet shape is preferred.
[0010]
Further, the present invention has a drying step of drying the above-mentioned molded body.
The “drying step” means a step of volatilizing the solvent contained in the molded body. At this time, the molding is performed by moving the molded body substantially horizontally inside the housing and flowing an airflow in a direction opposite to the direction in which the molded body moves above the molded body.
At this time, the “movement” means that the molded body may be moved in a substantially horizontal direction. If the molded body is substantially horizontal, the path through which the molded body moves may be a straight line or a curved line. . When the passage is straight, the passage may be bent in the middle. As a method of moving the carrier film substantially horizontally, for example, as shown in FIG. 1, the molding 5 can be arranged on a carrier film 31 and the carrier film 31 can be driven by a driving roller 32. .
[0011]
Further, the shape of the “housing” is not particularly limited, but is preferably, for example, a straight cylindrical shape as shown in FIG. The cross-sectional shape of the housing is not particularly limited, but is preferably a quadrangle. This is because an airflow described later can flow efficiently. Further, as shown in FIG. 2, the housing may be divided into a plurality of independent zones, and the airflow may flow through each of the independent zones. At this time, the number of the zones is not particularly limited, but is preferably 2 to 10, preferably 2 to 5, and more preferably 3 as shown in FIG.
[0012]
Further, in the present invention, the concentration of the solvent contained in the gas constituting the “air flow” can be gradually reduced in the direction in which the molded body moves. That is, the gas constituting the gas stream is in a state in which the solvent is contained due to the volatilization of the solvent contained in the molded body, but the concentration of the solvent contained in the gas becomes high immediately after the drying is performed. To do. This is because a large amount of the solvent is contained in the molded body, and thus a large amount of the solvent is first volatilized. Further, since the amount of the solvent contained in the molded body gradually decreases due to the volatilization of the solvent, the concentration of the solvent contained in the gas is reduced as the drying proceeds. At the end of drying, the concentration of the solvent contained in the gas is preferably substantially 0% by volume. The concentration of this solvent is determined by integrating the volume% at the time of the lower explosion limit with the LEL% (lower explosion lower limit reference concentration) measured by a catalytic combustion type combustible gas concentration measuring device adapted to the proportion of the prepared solvent. be able to. Furthermore, the concentration of this solvent may be from 0.03 to 1.8% by volume, preferably 0.05 to 1.5% by volume, in the first zone, if the housing is divided into three zones, 0 to 0.1% by volume, preferably 0 to 0.05% by volume, and 0 to 0.01% by volume, preferably less than 0.01% by volume in the third zone.
[0013]
Furthermore, when the housing is divided into a plurality of zones, it is preferable that the airflow velocity is the smallest in the zone where the compact enters first, and gradually increases in the direction in which the compact moves in each zone. That is, when the compact moves to the next zone, it is preferable that the flow velocity is higher than that of the previous zone, and furthermore, the flow velocity of the zone where the compact enters last is the highest.
This flow rate can be appropriately changed depending on the number of zones provided in the housing, the composition of the slurry, and the like. For example, when there are three zones, the flow velocity of this air flow can be appropriately changed depending on the composition of the slurry, etc., but in the case of a 1.66 m wide × 0.25 m high housing, the first zone has a flow rate of 0.05 to 0.05 m 2. 0.5 m / sec, preferably 0.1 to 0.3 m / sec, 0.1 to 1.5 m / sec in the second zone, preferably 0.5 to 1.2 m / sec, and 0.1 to 0.3 m / sec in the third zone. 1-3 m / sec, preferably 1-2 m / sec.
[0014]
Here, when the casing is not divided into a plurality of zones, the flow rate in the casing is not particularly limited as long as the drying is performed sufficiently, but the flow rate is 1.66 m wide × 0.25 m high. , 0.05 to 0.5 m / sec, more preferably 0.1 to 0.3 m / sec. At this time, it is preferable that the flow velocity in the housing is initially small and gradually increases as the molded body advances. As a method of changing the flow velocity, it is preferable to use a case in which the vertical sectional area of the case (cross-sectional area cut in the AA direction in FIG. 3) gradually decreases in the direction in which the molded body 5 advances. At this time, it is preferable that this vertical cross-sectional area is the largest on the side where the molded body 5 enters (the left side in FIG. 3) and the smallest on the side where the molded body 5 exits.
As shown in FIG. 3, for example, as the housing 21 having a gradually reduced vertical cross-sectional area, the height of the ceiling portion 214 on the side where the molded body 5 enters is increased and gradually decreased in the direction in which the molded body 5 advances. Are preferred. Furthermore, at this time, the height of the ceiling portion 214 on the side where the molded body 5 enters (the left side in FIG. 3) is the highest, and the side where the molded body 5 exits (the right side in FIG. 3) is the lowest. More preferred. Note that the shape of the ceiling portion 214 is not limited to a shape in which the height gradually changes as shown in FIG. 3, and may change, for example, stepwise downward in the direction in which the molded body 5 advances.
[0015]
Furthermore, the Reynolds number of the airflow is not particularly limited as long as the drying is sufficiently performed, but at least 20,000 or less from the start of drying until the concentration of the solvent contained in the airflow becomes 1% by volume or less. , Preferably 10,000 or less, and usually 1,000 or more. By not causing a strong turbulence in the airflow, drying can be performed without forming a resin film on the molded body. Therefore, it is possible to effectively prevent cracks and uneven thickness of the ceramic green sheet. Because it can be. The Reynolds number Re is calculated from the equivalent diameter De of the housing (when the cross section is rectangular: 2 × width × height / (width + height)), the average wind velocity u, the density ρ of the fluid, and the viscosity μ of the fluid. It is a dimensionless number obtained as Re = De × u × ρ × μ.
[0016]
The temperature of the air stream is not particularly limited as long as it is in a range where drying is sufficiently performed, but may be 20 to 80 ° C, preferably 30 to 70 ° C. In the case where the housing is divided into three zones, the first zone has a temperature of 20 to 50 ° C, preferably 30 to 50 ° C, and the second zone has a temperature of 30 to 80 ° C, preferably 40 to 70 ° C. In the three zones, the temperature can be 50 to 90 ° C, preferably 50 to 80 ° C.
[0017]
Further, in the present invention, the temperature of the molded body is gradually increased or kept constant in the direction in which the molded body moves. This temperature range can be 20-90 ° C, preferably 30-80 ° C, more preferably 30-70 ° C.
Furthermore, in the first zone, 20 to 70 ° C, preferably 30 to 60 ° C, in the second zone, 40 to 80 ° C, preferably 40 to 70 ° C, and in the third zone, 50 to 90 ° C, preferably 60 to 90 ° C. It can be 80 ° C.
Further, as a method for heating the molded body, there is a method in which a heater having hot water circulated in a tube is disposed below the molded body.
At this time, the temperature of the hot water can be gradually increased in the direction in which the molded body moves. That is, the temperature of the hot water is set to be low immediately after drying. Then, it is preferable to gradually increase the temperature of the hot water in a portion corresponding to the direction in which the molded body moves.
In the case where the housing is divided into three zones, it is preferable that this heater is mounted below the first zone and below the second zone, but not below the third zone.
Further, in the first zone, it is preferable that the temperature is increased shortly after drying, and in the second zone, the height is higher than or equal to the height of the first zone.
Further, the temperature of the hot water can be 30 to 50 ° C in the first zone and 45 to 80 ° C in the second zone.
Further, it is preferable that the temperature of the hot water is adjusted to be higher than the temperature of the airflow. If the temperature of the hot water is lower than the temperature of the airflow, a film tends to be formed on the ceramic green sheet.
[0018]
In the present invention, the ceramic green sheet (hereinafter, also referred to as a dried body) after the drying step can be further annealed. Thereby, the stress concentration generated inside the dried body can be released. The method of annealing is not particularly limited, and examples thereof include a method of immersing the dried body in warm water.
The thickness of the dried body is not particularly limited, but can be 100 μm or more, preferably 200 μm or more.
[0019]
[2] Manufacturing equipment
The apparatus for manufacturing a ceramic green sheet according to the present invention includes a molding unit for molding a slurry containing a ceramic powder, a resin, and a solvent into a sheet to produce a molded body; a drying unit for drying the molded body; Moving means for moving the body from the forming means to the drying means and further moving the inside of the drying means in a substantially horizontal direction.
The above-mentioned "forming means" is not particularly limited as long as the molded body can be produced, and examples thereof include a doctor blade method, a slip casting method and the like on a carrier film.
The "moving means" includes, for example, a carrier film 31 for arranging the molded body 5 on the surface thereof, a roller 32 for driving the carrier film, and a roller 32 for driving the roller 32 as shown in FIG. And a driving device (not shown) for driving the roller 32 to move the molded body 5 substantially horizontally together with the carrier film 31.
[0020]
The `` drying means '' includes a housing, airflow generating means for generating an airflow in a direction opposite to a direction in which the molded body moves above the molded body, and heating means for heating the molded body from below. is there.
The “housing” is not particularly limited as long as it is the predetermined one, and it is preferable to use one that is divided into a plurality of independent zones as shown in FIG. The description of the manufacturing method can be applied as it is to the airflow temperature in each zone and the concentration of the solvent contained in the gas constituting the airflow.
In the case where there is no plurality of independent zones, it is preferable to use a casing in which the longitudinal sectional area of the casing 21 gradually decreases in the direction in which the molded body 5 advances. At this time, it is preferable that this vertical cross-sectional area is the largest on the side where the molded body 5 enters, and further, the smallest on the side where the molded body 5 exits.
For example, as shown in FIG. 3, as the housing 21 having a gradually reduced vertical cross-sectional area, the height of the ceiling portion 214 on the side where the molded body 5 enters is high, and is gradually reduced in the direction in which the molded body 5 advances. Is preferred. Further, at this time, the height of the ceiling portion 214 on the side where the molded body 5 enters (the left side in FIG. 3) is the highest, and the height of the ceiling 214 on the side where the molded body 5 exits (the right side in FIG. 3) is the highest. More preferably, it is low. Note that the shape of the ceiling portion 214 is not limited to a shape in which the height gradually changes as shown in FIG. 3, and may change, for example, stepwise downward in the direction in which the molded body 5 advances. At this time, the description of the manufacturing method can be applied as it is to the flow velocity, the air flow temperature, and the concentration of the solvent contained in the gas constituting the air flow.
[0021]
The “airflow generating means” is attached to the housing to generate an airflow inside the housing. For example, as shown in FIG. 2 and FIG. The direction in which the molded body moves above the molded body 5 is a suction unit 221 that takes in the gas into the housing 21 through the casing 21 and an exhaust unit 222 that exhausts gas from the casing via the exhaust tube 2221 by the exhaust fan 2222. It is preferable to use a member arranged so that gas flows in the opposite direction.
The concentration of the gas constituting the airflow generated by the airflow generation means is adjusted so as to gradually decrease in the direction in which the molded body moves. Further, the description of the above-mentioned production method can be applied to the concentration of this gas as it is.
In the case where the housing is divided into a plurality of independent zones, the airflow generating unit is preferably provided with each of the intake unit 221 and the exhaust unit 222 in each zone as shown in FIG. .
[0022]
Further, the "heating means" is for adjusting the temperature of the molded body by heating the molded body from below, and includes, for example, a heater for circulating hot water through a pipe. The heating means is adjusted so that the temperature of the molded body gradually increases or becomes constant. This is for effectively preventing a film from being formed on the surface of the ceramic green sheet. At this time, the description of the manufacturing method can be applied as it is to the temperature of the molded body. Further, when the housing is divided into independent zones, it is preferable not to dispose the heating means at a location corresponding to the zone through which the molded article finally passes.
[0023]
【Example】
Hereinafter, examples embodying the present invention will be described.
[1] Configuration of manufacturing apparatus
The configuration of a ceramic green sheet manufacturing apparatus of the present embodiment (hereinafter, also simply referred to as the present manufacturing apparatus) will be described with reference to FIGS.
As shown in FIG. 1, the present manufacturing apparatus includes a molding unit 1 for producing a sheet-like molded body 5 from the slurry 4, a drying unit 2 for drying the molded body 5 to obtain a dried body, and a drying unit 2. It has a moving means 3 for moving the molded body 5 inside the housing 21 and an annealing means 6 for releasing the stress existing inside the dried body.
The forming means 1 includes a tank 11 for storing the slurry 4, and a doctor blade 12 for forming a sheet-like formed body 5 on the carrier film 31 from the slurry 4.
The moving means 3 includes a carrier film 31 on which the formed molded body 5 is disposed, and a roller 32 for driving the carrier film 31. The rotation of the roller 32 causes the carrier film 31 to move in the direction indicated by the arrow X together with the carrier film 31. The molded body 5 moves.
As shown in FIG. 2, the drying unit 2 includes a housing 21, an airflow generating unit 22 that generates an airflow in a direction opposite to a direction in which the molded body 5 moves, and a heating unit that heats the molded body 5 from below. 23.
The housing 21 has a cylindrical shape, and its cross section is a rectangle having a width of 1.66 m and a height of 0.25 m. The inside is divided into three zones (a first zone 211, a second zone 212, and a third zone 213) as shown in FIG. At this time, the length of the first zone 211 is 14 m, the length of the second zone 212 is 10 m, and the length of the third zone 213 is 6 m.
The airflow generating unit 22 includes an intake fan 221 that takes in gas for generating an airflow into each of the zones 211, 212, and 213 through the intake cylinder 2211 through the intake cylinder 2211, and an exhaust fan 2222 that supplies the air through the exhaust cylinder 2221. Exhaust means 222 for exhausting air from the zones are disposed in each of the zones 211, 212, and 213, and formed in each of the zones 211, 212, and 213 by the intake means 221 and the exhaust means 222 disposed in each of the zones 211, 212, and 213. An airflow is generated above the body 5 in a direction opposite to the direction X in which the molded body moves.
As the heating means 23, heaters 231, 232, 233, 234, 235 for heating by circulating hot water through a pipe are arranged. Three heaters 231, 232, and 233 are arranged in the first zone 211, and two heaters 234 and 235 are arranged in a portion corresponding to the second zone 212. Further, the heating means 23 is adjusted so that the temperature of the molded body 5 gradually increases or becomes constant.
[0024]
As shown in FIG. 1, the annealing means 6 includes a water bath 61 for immersing the molded body and a roller 62 for guiding the molded body 5 separated from the carrier film 31 to the water bath 61.
[0025]
[2] Examples and Comparative Examples
A ceramic green sheet was manufactured by the above manufacturing apparatus under the conditions shown in Table 1, and it was visually observed whether cracks occurred in the ceramic green sheets. Those which were confirmed were evaluated as "A", and those where cracks were remarkable were evaluated as "X". The slurry used in Examples 1 and 2 and Comparative Example was zirconia powder (specific surface area 3.8 m). ² / G) 100 parts by mass, 66.7 parts by mass of a solvent composed of 54% by mass of methyl ethyl ketone, 36% by mass of toluene and 10% by mass of ethanol (methyl ethyl ketone + toluene + ethanol = 100% by mass), and 11.5 parts by mass of butyral resin And 4.8 parts by mass of dibutyl phthalate as a plasticizer and 0.5 parts by mass of sorbitan monolaurate as a dispersant.
[0026]
[Table 1]

[0027]
[3] Effects of the embodiment
As shown in Table 1, when the concentration of the solvent contained in the airflow is the highest in the second zone (Comparative Example), the occurrence of cracks is remarkable. This indicates that the drying performance is not good when the solvent concentration is the highest in the second zone even if the airflow temperature and the temperature of the compact are gradually increased in the direction in which the compact advances.
On the other hand, when the solvent concentration is the highest in the first zone and the solvent concentration is 0% by volume in the third zone (Examples 1 and 2), generation of cracks is suppressed. Thereby, when the airflow temperature and the temperature of the compact are gradually increased in the direction in which the compact advances, and the concentration of the solvent contained in the gas is gradually reduced in the direction in which the compact advances, the drying performance is excellent. I understand.
Further, when the Reynolds numbers in the airflows of the first zone and the second zone were set to 3300 and 13000 (Example 1), generation of cracks was not confirmed. Accordingly, when the Reynolds number of the air flow from the time when the molded body enters the inside of the housing to the time when the concentration of the solvent contained in the air flow becomes 1% by volume is set to 3300 which is 20,000 or less, the drying is performed. It turns out that performance is extremely excellent.
Further, in the first embodiment, the temperature of the hot water circulated through the heating means 23 is adjusted to be higher than the temperature of the airflow. Further, the temperature of the heating means 23 is adjusted so that the center heater 232 is higher than the heater 231 in front of the first zone, and the temperature is gradually increased in the direction in which the molded body 5 moves. Has been adjusted. As a result, no film is formed on the ceramic green sheet. Therefore, it turns out that drying performance is more excellent.
[0028]
It should be noted that the present invention is not limited to those described in the above specific embodiments, but may be variously modified embodiments within the scope of the present invention depending on the purpose and application.
For example, in this embodiment, as shown in FIG. 2, the casing 21 is divided into zones, but as shown in FIG. 3, a casing which is not divided into zones may be used. . At this time, as for the shape and the like of the housing 21, the description of the above-described manufacturing apparatus can be applied as it is.
Further, in the present embodiment, the number of zones inside the housing is set to 3, but the number of zones is not particularly limited, and can be divided into 2 to 5 zones.
Further, in this embodiment, zirconia powder was used as the ceramic raw material. However, the present invention is not limited to this. For example, the same effect can be obtained by using alumina powder or the like.
[Brief description of the drawings]
FIG. 1 is a schematic view of an apparatus for manufacturing a ceramic green sheet according to an embodiment.
FIG. 2 is a schematic diagram illustrating an internal structure of a drying unit according to an embodiment.
FIG. 3 is a schematic diagram showing an internal structure of a drying unit according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1; Forming means, 2; Drying means, 21; Housing, 211; First zone, 212; Second zone, 213; Third zone, 214; Ceiling part, 22; Exhaust means 23; heating means 3; moving means 4; slurry 5; molded body 6; annealing means.

Claims (8)

In a method for producing a ceramic green sheet, comprising: a molding step of molding a slurry containing ceramic powder, a resin, and a solvent into a sheet to produce a molded body, and a drying step of drying the molded body,
The drying step generates an airflow in a direction opposite to a moving direction of the molded body while moving the molded body inside the housing, and gradually reduces a temperature of the molded body in a direction in which the molded body moves. Or maintaining the temperature constant, and gradually decreasing the concentration of the solvent contained in the gas stream in the direction in which the molded body moves. The method for manufacturing a ceramic green sheet according to claim 1, wherein the inside of the housing is divided into a plurality of zones, and an independent airflow is generated for each of the zones. The method for manufacturing a ceramic green sheet according to claim 2, wherein the flow velocity of the airflow is smallest in a zone where the compact enters first, and gradually increases in a direction in which the compact moves in each zone. The Reynolds number of the gas flow is 20,000 or less at least during a period from when the molded body enters the inside of the housing to when the concentration of the solvent contained in the gas constituting the gas flow becomes 1% by volume. 4. The method for producing a ceramic green sheet according to any one of 1 to 3. Forming means for forming a molded article by molding a slurry containing ceramic powder, resin and solvent into a sheet, drying means for drying the molded article, and moving the molded article from the molding means to the drying means Moving means for moving inside the drying means,
The drying unit includes a housing in which the molded body moves by the moving unit, and an airflow formed in the housing and flowing in a direction opposite to a direction in which the molded body moves above the molded body. Airflow generating means, comprising a heating means for heating the molded body from at least a lower portion,
The heating means heats the molded body so as to gradually raise or keep the temperature of the molded body constant, and the concentration of the solvent contained in the gas constituting the airflow generated by the airflow generation means is the following. An apparatus for producing a ceramic green sheet, wherein the apparatus is adjusted so as to gradually decrease in a direction in which a molded body moves. The casing is internally divided into a plurality of independent zones, and the airflow generating means includes an intake means for taking in gas into each of the zones and an exhaust means for discharging the gas from each of the zones. Prepare,
The ceramic green sheet according to claim 5, wherein the intake means and the exhaust means are arranged above the molded body so that the airflow is generated in a direction opposite to a direction in which the molded body moves. manufacturing device. The airflow generating means generates the airflow such that the flow velocity of the airflow in the zone where the compact enters first is the smallest, and the flow velocity gradually increases in the direction in which the compact moves in each zone. An apparatus for producing a ceramic green sheet according to claim 5 or 6. The airflow generating means has a Reynolds number of 20,000 or less from at least the time when the molded body enters the inside of the housing until the concentration of the solvent contained in the gas constituting the airflow becomes 1% by volume. The apparatus for producing a ceramic green sheet according to any one of claims 5 to 7, which generates an air current.

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