JP2005271366A - Method and apparatus for drying ceramic green sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for drying a ceramic green sheet capable of uniformly drying it over the whole face of the ceramic green sheet and decreasing an unevenness of the thickness. <P>SOLUTION: In the apparatus 1 for drying the ceramic green sheet, by making a hot wind from the upper face side a very little, there exists no possibility of putting the surface of the green sheet 50 not sufficiently dried into disorder, and in addition, by controlling the flow rate of the hot wind from the lower face side to distribute it in the width direction, it is possible to uniformly dry it in the width direction. Therefore, it is possible to prevent the thickness of the green sheet 50 from scattering in a drying process, and to suppress scattering of shrinkage in a calcining process to be a little. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ceramic green sheet drying apparatus and drying method, and more particularly, to a ceramic green sheet drying apparatus and drying method for drying a ceramic green sheet from an upper surface side and a lower surface side of the sheet.

In general, in a method for producing a ceramic green sheet by a doctor blade method, a slurry containing ceramic supplied to a dam is applied to the upper surface of a carrier film with a doctor blade having a certain thickness, and then the green sheet is placed in a drying apparatus. The sheet is dried while being conveyed on the formed conveyance path, and the sheet is dried by hot air supplied from a heater, a fan or the like provided on the upper surface side and the lower surface side thereof. Since the ceramic green sheet is less likely to be dried at the center in the width direction than at the end in the width direction, drying unevenness, film cracking, etc. may occur in the width direction. Technology is disclosed. For example, in the method for producing a ceramic green sheet according to Patent Document 1, hot air is blown onto the sheet from the upper surface side for drying, and the flow speed of the hot air is increased at the center in the width direction of the sheet, and from there to the end in the width direction. The flow rate of the hot air is gradually decreased toward the front, whereby the central portion is dried earlier than the end portion in the width direction of the sheet.
Japanese Patent No. 2507532

  However, in the related art as described in Patent Document 1, since the hot air is blown from the upper surface side of the sheet and drying is performed, the sheet surface is disturbed by the wind hitting the sheet that is not sufficiently dried, There was a problem that it was difficult to make the sheet thickness uniform. In addition, if the sheet thickness is not uniform, there is a possibility that the variation in shrinkage during firing may be affected. For example, the sheet thickness of the sheet is 2% or less as in the case of producing a low-temperature fired substrate for a high-frequency element circuit board. When high accuracy is required, there is a problem that the request cannot be met.

  The present invention has been made to solve the above-described problem, and can be uniformly dried over the entire surface of the ceramic green sheet, and the thickness of the ceramic green sheet can be reduced. An object is to provide an apparatus.

  In order to achieve the above object, the method for drying a ceramic green sheet according to claim 1 is a method for drying the ceramic green sheet by heat conduction while transporting the ceramic green sheet on a heating chamber to which hot air is supplied. In at least the initial drying stage, the temperature of the hot air in the heating chamber is increased at the center in the width direction of the ceramic green sheet, and the speed of the hot air is gradually decreased toward the both ends, thereby controlling the ceramic green sheet. It is characterized in that it is dried uniformly from the lower surface side in the width direction, and the volatilized solvent component is discharged to the outside of the apparatus by flowing a breeze on the upper surface side of the ceramic green sheet.

  The ceramic green sheet drying apparatus according to claim 2, wherein the ceramic green sheet is dried by heat conduction while being conveyed on a heating chamber to which hot air is supplied, and is at least in an initial drying stage. In the heating chamber, the ceramic green sheet is controlled from the lower surface side to the width direction by controlling the hot air speed to be large at the center in the width direction of the ceramic green sheet and gradually decreasing toward the both ends. A hot air volume adjustment mechanism is provided for drying evenly, and on the top side of the ceramic green sheet, a supply / exhaust system capable of supplying fine wind for discharging the volatilized solvent component to the outside of the apparatus is provided. Features.

  In addition to the configuration of the ceramic green sheet drying apparatus according to claim 2, the ceramic green sheet drying apparatus according to claim 3 includes a plurality of ceramic green sheet drying apparatuses arranged in the width direction of the ceramic green sheet in the heating chamber. A hot air blowing nozzle is provided, and a damper for adjusting the air volume is provided at the blowing nozzle, and the speed of the hot air is increased at the center in the width direction of the ceramic green sheet, and the speed of the hot air is gradually decreased toward both ends. Then, drying is performed uniformly in the width direction on the lower surface side of the ceramic green sheet.

  Moreover, in the ceramic green sheet drying apparatus according to claim 4, in addition to the configuration of the green sheet drying apparatus according to claim 3, a partition extending in the length direction of the conveyor between the plurality of hot air blowing nozzles. Each plate is provided.

  In the method for drying a ceramic green sheet according to the present invention, when the ceramic green sheet is dried by heat conduction while being transported on a heating chamber to which hot air is supplied, the hot air in the heating chamber is at least in the initial drying stage. Is controlled so that the speed of the hot air gradually decreases toward the both ends of the ceramic green sheet in the width direction, and the ceramic green sheet is uniformly dried in the width direction from the lower surface side. Then, a small breeze was made to flow on the upper surface side of the ceramic green sheet to discharge the volatilized solvent component out of the apparatus. Thereby, drying can be performed mainly from the lower surface side of the sheet, and the hot air from the upper surface side does not affect the undried surface of the sheet and the sheet thickness does not increase or decrease. Further, by controlling the speed of hot air on the lower surface side of the sheet, the sheet can be dried uniformly in the width direction, and the thickness of the sheet can be made constant. Therefore, it is possible to cope with a case where high accuracy is required for the plate thickness.

  In the ceramic green sheet drying apparatus according to the present invention, the hot air speed is increased at the center in the width direction of the ceramic green sheet at least in the heating chamber in the initial drying stage, and the hot air speed gradually increases toward both ends. An air volume adjustment mechanism is provided to dry the ceramic green sheet evenly in the width direction from the lower surface side by controlling it so that it becomes smaller. An air supply / exhaust system capable of supplying a breeze to discharge was provided. Therefore, it is possible to cope with a case where high accuracy is required for the plate thickness.

  In addition, a plurality of hot air blowing nozzles arranged in the sheet width direction are provided in the heating chamber, a damper for adjusting the air volume is provided in the blowing nozzle, and the speed of the hot air is increased at the center in the width direction of the ceramic green sheet, Since the partition plates extending in the length direction of the conveyor are provided between the plurality of hot-air blowing nozzles, each region sandwiched between the partition plates is controlled so that the speed of the hot air gradually decreases toward the In addition, the speed of the hot air can be reliably controlled, and the thickness of the sheet can be made constant by drying the sheet uniformly in the width direction. Therefore, it is possible to cope with a case where high accuracy is required for the plate thickness.

  Hereinafter, an embodiment of a ceramic green sheet drying apparatus and drying method embodying the present invention will be described with reference to the drawings. First, with reference to FIG. 1, the manufacturing process of a ceramic green sheet is demonstrated easily. As shown in FIG. 1, the ceramic green sheet supplies the slurry 20 to the dam 19 and moves the carrier film 70 together with the conveyor belt 80 stretched around a plurality of rotatable rollers 150 in the right direction (hereinafter referred to as “conveyance”). The slurry 20 passes through the gap between the doctor blade 21 provided in the dam 19 and the carrier film 70 so that the slurry 20 has a constant thickness on the carrier film 70. After the coating, the solvent is evaporated in the drying apparatus 1 to be dried. In the present embodiment, the left side in the figure is the upstream side in the transport direction, that is, the initial drying stage side, the right side is the downstream side in the transport direction, that is, the late drying stage side, and the middle part of these initial and late drying stages is the intermediate drying stage. .

  The drying device 1 has a box shape extending long in the length direction of the conveyor belt 80 (left and right direction in the figure), and is divided into a plurality of drying zones 11 to 13 along the length direction. The conveyor belt 80 and the carrier film 70 pass through the plurality of drying zones 11 to 13 through the intermediate portion in the vertical direction of the drying apparatus 1, and the carrier film 70 is moved along with the movement of the conveyor belt 80 in the transport direction. The upper green sheet 50 moves in the transport direction while being dried in each of the drying zones 11 to 13. In each of the drying zones 11 to 13, spaces are formed above and below the conveyor belt 80, the carrier film 70, and the green sheet 50, and hot air for drying the green sheet 50 is supplied to the portions. A heater 110 and a fan 111 are provided. Accordingly, the drying apparatus 1 performs drying by blowing hot air from both the upper surface side and the lower surface side of the green sheet 50, and the hot air from the upper surface side directly hits the green sheet 50. Since the hot air from directly hits the conveyor belt 80, the green sheet 50 is not dried by the wind but dried by heat conduction on the lower surface side. In addition, the mesh-shaped thing which consists of a resin-type material can be used as the conveyor belt 80, and a hot air flows toward the direction of the filling arrow in a figure in each drying zone.

  Further, in the drying apparatus 1, in the drying zones 11 and 12 in the initial and intermediate drying stages, drying by directly blowing hot air from the upper surface side is not actively performed, and drying by heat conduction from the lower surface side is not performed. Is actively doing. Specifically, in the drying zones 11 and 12 in the initial and intermediate drying stages, the amount of hot air from the upper surface side is very small, and the solvent component volatilized on the upper surface side by the hot air from the lower surface side is discharged out of the apparatus. Yes. As will be described later, the hot air from the upper surface side is not used for drying in the drying zones in the initial and intermediate drying stages when the hot air is blown directly onto the surface of the sheet in a state where the green sheet 50 is not yet sufficiently dried. This is because the surface may be affected by hot air and the sheet thickness may become non-uniform.

  The drying from the lower surface side is performed by hot air supplied from the heater 110 and the fan 111 provided on the lower surface side, and hot air is blown out to the heater 110 and the fan 111 as shown in FIGS. A blowing nozzle 25 is connected. Here, FIG. 2 is a schematic view showing a state of one drying zone in plan view, showing the structure of the nozzles 25 and the positional relationship of the nozzles 25 with respect to the conveyor belt 80, the carrier film 70 and the green sheet 50. 3 is a schematic view showing a state in which one drying zone is viewed from the downstream side in the transport direction, and shows the structure of the nozzle 25 and the like as in FIG. The blowing nozzle 25 is slightly wider than the conveyor belt 80 and is equally divided into ten in the width direction of the green sheet 50, and ten blowing ports are formed at the tip thereof. A partition plate 27 extending in the transport direction is provided between the blowout ports of the nozzle 25 divided into ten, and ten independent hot air flow paths 31 to 40 are formed by the partition plate 27. An exhaust duct 125 for circulating hot air supplied from the nozzle 25 is provided at the end of the hot air flow path 31 to 40 opposite to the nozzle 25, and the nozzle 25, the partition plate 27, and the exhaust duct 125 are provided. Are accommodated in a heating chamber 130 having a substantially rectangular parallelepiped housing shape provided immediately below the conveyor belt 80.

  A damper 26 for controlling the flow rate of the hot air blown out is provided at each outlet of the nozzle 25 divided into ten, and the flow rate of the hot air in each hot air flow path 31 to 40 is illustrated by the damper 26. The flow velocity distribution as shown in FIG. 4 is controlled. Here, the length of the arrow in FIG. 4 indicates the magnitude of the flow velocity. Specifically, as shown in FIG. 4, the flow rate is increased in the two flow paths in the center portion in the width direction, and accordingly, the flow velocity of the hot air is increased in the center portion in the width direction. That is, the green sheet 50 receives a large amount of heat at the center in the width direction which is relatively difficult to dry. Then, the flow rate is gradually decreased from the central portion in the width direction toward each end portion in the width direction, and accordingly, the flow velocity of the hot air is reduced at each end portion in the width direction. That is, the green sheet 50 receives a small amount of heat at the edge portion in the width direction which is relatively easy to dry. Therefore, the green sheet 50 can be uniformly dried in the width direction by making the flow velocity at the center portion in the width direction larger than the end portion in the width direction, and drying unevenness is prevented.

  Further, although not shown in detail, the heater 110 and the fan 111 provided on the upper surface side are connected to a nozzle for supplying hot air having a plurality of outlets arranged in the width direction similar to the nozzle 25, The solvent component volatilized on the upper surface side by hot air from the nozzle is discharged, and the green sheet 50 is dried from the upper surface side.

  Further, in the drying zone 13 in the late drying stage, a counterflow that blows hot air toward the green sheet 50 from the downstream side in the conveying direction to the upstream side is adopted, whereby the length of the green sheet 50 is increased. Generation of uneven drying can be prevented, and uniform drying can be realized not only in the width direction but also in the length direction. In addition, on the lower surface side of the green sheet 50, hot air is blown to the green sheet 50 as a velocity distribution as described above not only in the drying zones 11 and 12 in the initial and middle drying stages but also in the drying zone 13 in the latter drying stage. While possible, it is not necessary to have a similar velocity distribution across the entire drying zone.

  Next, a drying method using the drying apparatus 1 described above will be described with reference to the drawings. As shown in FIG. 1, in forming the green sheet 50 by drying the slurry 20 in the drying apparatus 1, first, the lower surface of the green sheet 50 is dried in the drying zones 11 and 12 in the initial and intermediate drying stages of the drying apparatus 1. Dry by blowing hot air from the side. At this time, hot air is not blown directly onto the sheet on the upper surface side, and the solvent component volatilized from the lower surface side to the upper surface side is discharged out of the apparatus with a small amount of hot air. On the lower surface side of the sheet in the drying zones 11 and 12 in the initial and intermediate drying stages, hot air is blown so that the flow velocity at the center in the width direction of the sheet is large and the flow velocity at the end is small, so that the sheet is in the width direction. To dry evenly.

  The green sheet 50 dried to some extent in the drying zones 11 and 12 in the initial and intermediate drying stages is conveyed in the conveying direction on the conveyor belt 80 and the carrier film 70 and further dried in the drying zone 13 in the latter drying stage. In addition, on the lower surface side of the green sheet 50, hot air is blown to the green sheet 50 as a velocity distribution as described above not only in the drying zones 11 and 12 in the initial and middle drying stages but also in the drying zone 13 in the latter drying stage. Although it is possible, the hot air supplied from the lower surface side does not necessarily have the same velocity distribution over the entire drying zone.

  Actually, when drying was performed under various conditions, a difference in shrinkage variation in the firing process could be confirmed. Table 1 shows the results when a ceramic green sheet having a thickness of 150 μm and a width of 1 m is dried under various conditions in a drying apparatus having the same three drying zones as the drying apparatus 1 of the present embodiment. Show. Here, in condition 1, the hot air velocity on the upper surface side is set to 0.2 m / s or more in the drying zone in the initial drying stage, and from the lower surface side, the temperature difference (heating) between the central portion in the width direction of the sheet and the left and right end portions. In condition 2, in the drying zone in the initial drying stage, the hot air velocity on the upper surface side is 0.2 m / s or less, and the heating variation from the lower surface side is 2 ° C. In condition 3, in the drying zone in the initial drying stage, the hot air velocity on the upper surface side is set to 0.2 m / s or less and the heating variation from the lower surface side is 1 ° C. Each sheet is dried.

  As is clear from Table 1, when hot air is positively blown from the upper surface side in the drying zone in the initial drying stage, and when hot air from the upper surface side is made in the drying zone in the initial drying stage Thus, it can be seen that the latter has less thickness variation. In addition, if the sheet is dried evenly in the width direction by controlling the amount of hot air on the upper surface side in the drying zone in the initial drying stage and controlling the air volume distribution of the hot air on the lower surface side, the thickness variation becomes smaller and the initial The thickness variation can be further reduced by further finely controlling the air volume distribution of the hot air on the lower surface side in the drying zone in the drying stage and finely controlling the air volume distribution of the hot air on the lower surface side.

  As described above, in the ceramic green sheet drying apparatus and drying method of the present invention, the surface of the green sheet that is not sufficiently dried can be obtained by making the amount of hot air from the upper surface side small in the drying zone in the initial drying stage. It is not disturbed by the wind, and by distributing and controlling the flow rate of the hot air from the lower surface side in the width direction, it can be dried uniformly in the width direction. Therefore, variation in sheet thickness can be prevented in the drying process, and shrinkage variation in the firing process can be reduced.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, in the present embodiment, drying is performed using a counter flow after the initial and intermediate drying stages, but the counter flow or drying using a nozzle capable of supplying hot air with a large amount of heat or a combination thereof is continuously employed. Also good. In this embodiment, the drying zone of the green sheet is divided into three. However, a drying device may be configured by four or more drying zones. In each drying zone, a nozzle in a chamber immediately below the green sheet is provided. Although divided into ten, it goes without saying that the nozzle may be divided into more or less divisions.

1 is a diagram schematically showing an overall configuration of a drying apparatus 1. FIG. It is the schematic which shows the state which planarly viewed one drying zone. It is the schematic which shows the state which looked at one drying zone from the conveyance direction downstream. It is a figure which shows the flow velocity distribution of the hot air in the lower surface side of the green sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Drying device 11, 12, 13 Drying zone 19 Dam 20 Slurry 21 Doctor blade 25 Nozzle 26 Damper 27 Partition plate 31-40 Hot air flow path 50 Ceramic green sheet 70 Carrier film 80 Conveyor belt 110 Heater 111 Fan

Claims (4)

The ceramic green sheet is a method for drying a ceramic green sheet, wherein the ceramic green sheet is dried by heat conduction while being conveyed on a heating chamber to which hot air is supplied.
At least in the initial drying stage, the temperature of the hot air in the heating chamber is controlled to be large at the center in the width direction of the ceramic green sheet, and the speed of the hot air gradually decreases toward both ends, so that the ceramic green sheet A method for drying a ceramic green sheet, wherein the ceramic green sheet is uniformly dried with respect to the width direction from the side, and the solvent component volatilized by flowing a gentle wind over the ceramic green sheet upper surface side is discharged outside the apparatus. A ceramic green sheet drying apparatus that dries a ceramic green sheet by heat conduction while being conveyed on a heating chamber to which hot air is supplied.
At least in the heating chamber in the initial drying stage, the ceramic green sheet is controlled on the lower surface side by controlling the speed of the hot air at the center in the width direction of the ceramic green sheet and gradually decreasing the speed of the hot air toward both ends. Supplying and exhausting equipment that can supply hot air to adjust the air flow in the width direction from the top to the bottom of the ceramic green sheet. An apparatus for drying a ceramic green sheet, comprising:   In the heating chamber, a plurality of hot air blowing nozzles arranged in the width direction of the ceramic green sheet are provided, a damper for adjusting the air volume is provided in the blowing nozzle, and the speed of the hot air is increased at the center in the width direction of the ceramic green sheet, 3. The ceramic green sheet according to claim 2, wherein the drying is performed uniformly in the width direction on the lower surface side of the ceramic green sheet by controlling so that the speed of the hot air gradually decreases toward both ends. Drying equipment.   4. The ceramic green sheet drying apparatus according to claim 3, wherein a partition plate extending in a length direction of the conveyor is provided between the plurality of hot air blowing nozzles.

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