Lamination apparatus for ceramic green sheets

Abstract

To efficiently fabricate a ceramic green sheet having superior strength and insulation properties after calcination.SOLUTION: A lamination apparatus 1 for ceramic green sheets, which is an apparatus for fabricating a laminated sheet by bonding plural green sheets with an adhesive liquid, comprises: a sheet pressure-contacting mechanism 2 that sandwiches the plural green sheets between a pair of pressure rollers 3a, 3b disposed facing each other in a horizontal direction and allows the green sheets to pass through while being pressed in an overlapped state; an adhesive liquid supply mechanism 6 that supplies the adhesive liquid to a trough V formed between green sheets 50a, 50b immediately before being sandwiched into the pressure rollers 3a, 3b; and a shuttering mechanism 9 inside which are provided a pair of shuttering plates 10a, 10b having respective inner wall faces 11a, 11b that are located inside relative to respective side edges 51a1 to 51b2 of the green sheets 50a, 50b that form the trough V, and which forms a liquid storage 13 therebetween by shuttering an adhesive liquid 53 supplied from the adhesive liquid supply mechanism 6.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a novel apparatus for manufacturing a sheet laminate formed by stacking ceramic green sheets. [Background technology]

[0002] As a method for producing a sintered body of a ceramic such as a nitride ceramic such as aluminum nitride or silicon nitride, or an oxide ceramic such as alumina, a method is generally adopted in which a powder of the above ceramic (hereinafter referred to as ceramic powder) is molded into a desired shape using an organic binder, followed by degreasing and firing the green body. A representative method for producing a ceramic green sheet, in which the green body is in the form of a sheet, is the doctor blade method. In this method, a slurry containing ceramic powder and an organic binder is supplied to a certain thickness onto a cast film through the gap between the moving cast film and the blade, and then the solvent is removed to obtain a ceramic green sheet (sometimes simply called a "green sheet"). This method makes it possible to produce a large-area ceramic green sheet with high precision. However, the thickness of the ceramic green sheet that can be produced by the doctor blade method is limited to about 1 mm due to the viscosity of the slurry, and it has been difficult to produce sheets thicker than this with high precision.

[0003] Therefore, for example, in the production of ceramic green sheets having a thickness of about several millimeters, which is required for applications such as electric railway control system boards, a method can be considered in which relatively thin ceramic green sheets produced by the above-mentioned doctor blade method are stacked to produce a sheet laminate having the desired thickness. A commonly known method for manufacturing the above-mentioned sheet laminate involves coating the surface of a ceramic green sheet with an adhesive, placing another ceramic green sheet on the coated surface, and pressing the sheets through rollers to form a laminate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2-219603 Summary of the Invention [Problem to be solved by the invention]

[0005] In the case of the invention disclosed in the above-mentioned Patent Document 1, problems such as unevenness in the thickness of the adhesive applied to the ceramic green sheets and air bubbles getting caught between the ceramic green sheets due to the joining speed of the ceramic green sheets occur. For this reason, in a ceramic sintered body obtained by firing a sheet laminate in which a plurality of ceramic green sheets are stacked, the above-mentioned air bubbles remain as voids, which inevitably reduces the strength of the ceramic sintered body itself and reduces the insulating properties when used as an insulating substrate. In other words, when Patent Document 1 is taken into consideration, it was difficult to efficiently mass-produce a laminated sheet that has excellent strength and insulation properties after firing and can exhibit these properties approximately uniformly over the entire area in the planar direction of the final product, that is, a flat ceramic sintered body.

[0006] The present invention has been made in response to such conventional circumstances, and its purpose is to provide a ceramic green sheet lamination device that can efficiently mass-produce laminated sheets that have excellent strength and insulation properties after firing and that can exhibit these properties approximately uniformly throughout the entire planar direction of the final product, a flat-plate-shaped ceramic sintered body. [Means for solving the problem]

[0007] The ceramic green sheet lamination device, which is a first invention for solving the above-mentioned problems, is an apparatus for bonding a plurality of ceramic green sheets together with an adhesive liquid to form a laminated sheet, and is characterized in that it comprises a sheet pressing mechanism which sandwiches and presses a plurality of ceramic green sheets between a pair of pressure rollers arranged opposite to each other in the horizontal direction from above, and passes the sheets in a stacked state, while being stacked, between the two pressure rollers; an adhesive liquid supply mechanism which supplies adhesive liquid to a valley formed between the ceramic green sheets just before they are sandwiched between the two pressure rollers; and a damming mechanism which has a pair of dams whose inner wall surfaces are located inside each of the side edges of the ceramic green sheets that form the valley, and which dams the adhesive liquid supplied from the adhesive liquid supply mechanism between them to form a liquid pool. In the first invention, by forming a pool of adhesive liquid in the valley portion formed between each ceramic green sheet, air bubbles contained in the adhesive liquid naturally move to the liquid surface of the pool. This makes it possible to efficiently remove air bubbles from the adhesive liquid forming the pool. In other words, the possibility of air bubbles being present in the adhesive liquid present at the bottom position of the valley portion becomes extremely low. This has the effect of minimizing the inclusion of air bubbles together with the adhesive liquid between the bonding surfaces of the ceramic green sheets when the ceramic green sheets are sandwiched between the pair of pressure rollers by the rotation of the pressure rollers.

[0008] A second invention is the above-mentioned first invention, characterized in that the adhesive liquid supply mechanism includes a liquid level control means for controlling the liquid level in the above-mentioned liquid pool. The liquid level control means in the second aspect of the invention has the effect of controlling the liquid level of the liquid pools formed in the valleys of the ceramic green sheets to a preset target value or to approximate the same. This has the effect of keeping the speed at which each ceramic green sheet is sandwiched between the pair of pressure rollers as constant as possible.

[0009] The third invention is the first or second invention described above, characterized in that it is provided with a side edge cutting means that is provided downstream of the pair of pressure rollers and cuts off areas of a predetermined width on both side edges of the laminated sheet. The side edge cutting means in the third invention having the above configuration has the effect of removing areas of the laminated sheet that do not have adhesive sandwiched therebetween, thereby producing a laminated sheet having a uniform amount of adhesive sandwiched therebetween.

[0010] The fourth invention is the first or second invention described above, characterized in that a gap capable of maintaining the liquid sealing property of the adhesive liquid is formed between the lower edge of the inner wall surface of the dam and the surface of the ceramic green sheet forming the valley portion. In the fourth invention, when a pair of dams are provided in the valleys formed by each ceramic green sheet, the lower edges of the dams come into contact with the surfaces of the ceramic green sheets, thereby preventing damage to the ceramic green sheets immediately before they are sandwiched between a pair of pressing rollers.

[0011] A fifth invention is the above-mentioned first or second invention, characterized in that it further comprises a pressing force adjusting means for adjusting the pressing force applied by both pressing rollers to the overlapping portions of the multiple ceramic green sheets. The pressing force adjusting means in the fifth aspect of the invention has the function of adjusting the pressing force acting on the ceramic green sheet sandwiched between the pair of pressing rollers to a desired value. In this case, even if the ceramic green sheets as raw materials have various thicknesses, rather than just one type, a laminated sheet can be produced using one ceramic green sheet lamination device.

[0012] A sixth invention is the above-mentioned first or second invention, characterized in that the apparatus further comprises a winding means provided downstream of the pair of pressure rollers and winding up the laminated sheet. The winding means in the sixth aspect of the invention has the effect of making the recovery mechanism for the produced laminated sheet compact. Effect of the Invention

[0013] According to the first aspect of the present invention as described above, a laminated sheet in which almost no air bubbles exist between the bonding surfaces of the ceramic green sheets can be easily produced. In this case, when the laminated sheet is fired to form a flat ceramic sintered body, the generation of voids therein due to the air bubbles can be suppressed as much as possible. As a result, according to the first invention, the strength and insulation properties of the flat plate-shaped ceramic sintered body, which is the final product, can be improved, so that a higher quality ceramic sintered body can be easily produced.

[0014] According to the second invention, a high-quality laminated sheet can be continuously produced. In this case, a laminated sheet having more uniform quality in the planar direction can be produced more efficiently than in a case where the liquid level in the puddle does not reach or is not close to the target value. Therefore, according to the second aspect of the present invention, high-quality flat-plate sintered ceramic bodies having excellent strength and insulation properties can be efficiently mass-produced.

[0015] According to the third invention, a laminate sheet can be efficiently manufactured in which the amount of adhesive liquid sandwiched between the bonding surfaces of the laminate sheet is uniform in the planar direction. As a result, according to the third invention, the yield of the final product can be increased.

[0016] According to the fourth invention, the risk of the ceramic green sheet being damaged or broken immediately before being sandwiched between the pair of pressure rollers can be significantly reduced compared to when the lower edge of the inner wall surface of the dam contacts the surface of the ceramic green sheet. Therefore, according to the fourth aspect of the present invention, the risk of the laminate sheet being produced becoming defective can be significantly reduced. As a result, according to the fourth aspect of the present invention, the productivity of the plate-shaped ceramic sintered body, which is the final product, can be improved.

[0017] According to the fifth aspect of the present invention, it is possible to increase the versatility of the thickness of the ceramic green sheet supplied as a raw material. Therefore, according to the fifth aspect of the present invention, a thicker, flat-plate-shaped ceramic sintered body can be produced inexpensively and efficiently.

[0018] According to the sixth aspect of the present invention, the planar size of the ceramic green sheet lamination device can be made compact. As a result, the scale of the manufacturing equipment for the final product, a flat ceramic sintered body, can be minimized as compared with a case in which the ceramic green sheet lamination device does not have a winding means. [Brief description of the drawings]

[0019] [Figure 1] 1 is a conceptual diagram of a main part of a lamination device for ceramic green sheets according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view taken along line AA in FIG. 1. [Diagram 3] FIG. 13 is a schematic diagram of a main part of a ceramic green sheet lamination device according to the present embodiment, which is provided with a liquid level control means according to a modified example. [Figure 4] 4 is a conceptual diagram of a side edge cutting means in the ceramic green sheet lamination device according to the embodiment. FIG. [Diagram 5] 4 is a conceptual diagram showing an example of a drive mechanism for a pair of pressure rollers in the ceramic green sheet lamination device according to the embodiment. FIG. [Figure 6] FIG. 2 is a vertical cross-sectional image diagram of a lamination device for ceramic green sheets according to the present embodiment. [Figure 7] FIG. 11 is a perspective view showing a modified example of a dam in the ceramic green sheet lamination device according to the embodiment. [Figure 8] FIG. 11 is a partial cross-sectional view of a ceramic green sheet lamination device according to the present embodiment, which is provided with a dam according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] A ceramic green sheet lamination apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS.

[0021] [1; Basic configuration of the present invention] A ceramic green sheet lamination apparatus according to a representative embodiment of the present invention (hereinafter, referred to as this embodiment) will be described below. Prior to the description, a ceramic green sheet used as a raw material in the ceramic green sheet lamination device according to this embodiment will be described.

[0022] The ceramic green sheet used in this embodiment is not particularly limited as long as it is a sheet made of a composition containing ceramic powder, an organic binder, and, if necessary, a sintering aid. Specifically, ceramic green sheets obtained by molding methods such as the doctor blade method, the casting method, and the extrusion molding method are preferred because they can be continuously manufactured and, after molding, can be wound into a roll as necessary and can be continuously used in the method of the present invention. Among them, ceramic green sheets obtained by the doctor blade method are preferably used. The thickness of the ceramic green sheet is not particularly limited, but is generally 0.05 to 1 mm, and more preferably 0.1 to 0.8 mm. The above-mentioned method for producing a ceramic green sheet is suitable for producing a ceramic green sheet having a thickness in the above range with high accuracy.

[0023] As the ceramic powder constituting the ceramic green sheet of this embodiment, any known sintering material, such as oxide ceramics including alumina, and nitride ceramics including aluminum nitride and silicon nitride, can be used without any particular limitation. As the organic binder, any known binder used in the production of ceramic green sheets may be used without any particular limitation. In particular, taking into consideration the flexibility of the sheet after molding, ease of degreasing, etc., PVB, PVA, acrylic resins, etc. are preferably used. Furthermore, the sintering aid, which is mixed in an appropriate amount as required, may be any sintering aid that is normally used for the ceramic powder used, without any particular limitation. In the present invention, the blending ratio of the ceramic powder and the organic binder can be appropriately determined within a range in which the ceramic green sheet exhibits flexibility, but generally, a range of 5 to 20 parts by mass of the organic binder per 100 parts by mass of the ceramic powder is suitable.

[0024] In the present invention, the lamination of ceramic green sheets is generally performed by laminating ceramic green sheets of the same type to produce a thick product, but this is not limited thereto, and a mode in which ceramic green sheets of the same type but different thicknesses are laminated may also be adopted. Furthermore, if co-firing is possible, a mode in which ceramic green sheets of different ceramic types are laminated may also be adopted. Specifically, examples of the ceramic green sheets include ceramic green sheets with the same chemical composition but different crystal types, and ceramic green sheets with different chemical compositions.

[0025] In this embodiment, when it is necessary to distinguish between multiple ceramic green sheets for the purpose of explaining the operation of the device, etc., they will be referred to as "ceramic green sheets 50a, 50b," and when simply referring to the ceramic green sheets collectively, they will be referred to as "ceramic green sheet 50."

[0026] Next, a specific embodiment of the ceramic green sheet lamination device according to this embodiment will be described with reference to FIGS. FIG. 1 is a schematic diagram of a main part of a ceramic green sheet lamination device according to this embodiment, and FIG. 2 is a cross-sectional view taken along line AA in FIG. The ceramic green sheet lamination apparatus 1 according to this embodiment is an apparatus for laminating a plurality of (for example, two) ceramic green sheets together with an adhesive liquid to form one laminated sheet. As shown in, for example, FIGS. 1 and 2, the ceramic green sheet lamination device 1 according to this embodiment includes a sheet pressing mechanism 2 that sandwiches and presses a plurality of (for example, two) ceramic green sheets 50a, 50b between a pair of pressing rollers 3a, 3b provided opposite to each other in the horizontal direction from above the two pressing rollers 3a, 3b, and passes the stacked ceramic green sheets 50a, 50b through the two pressing rollers 3a, 3b in a stacked state. The sheet pressing mechanism 2 presses and presses the ceramic green sheets 50a, 50b in a valley V formed between the ceramic green sheets 50a, 50b immediately before they are sandwiched between the two pressing rollers 3a, 3b. The apparatus further includes an adhesive liquid supplying mechanism 6 for supplying an adhesive liquid 53 for bonding the ceramic green sheets 50a, 50b together, and a pair of weirs 10a, 10b whose inner wall surfaces 11a, 11b are located inside side edges 51a1, 51a2 of the ceramic green sheet 50a and side edges 51b1, 51b2 of the ceramic green sheet 50b that form the valley portion V, and a damming mechanism 9 for damming the adhesive liquid 53 supplied from the adhesive liquid supplying mechanism 6 between the inner wall surfaces 11a, 11b of the pair of weirs 10a, 10b to form a liquid pool 13.

[0027] That is, in the damming mechanism 9, as shown in FIG. 1 and FIG. 2, a pair of dams 10a, 10b are arranged spaced apart from each other along the rotation axes of both pressing rollers 3a, 3b in a valley portion V formed between the ceramic green sheets 50a, 50b, and the adhesive liquid 53 is dammed up between the inner wall surfaces 11a, 11b of the pair of dams 10a, 10b. As a result, the two ceramic green sheets 50a, 50b forming the valley portion V and the weirs 10a, 10b spaced apart from each other cooperate to form a container structure having an opening at the top, and adhesive liquid 53 is stored in the space within the container structure to form a liquid pool 13. In order to prevent the adhesive liquid 53 stored in the liquid puddle 13 from adhering to both pressing rollers 3a, 3b when multiple ceramic green sheets 50 are sandwiched between a pair of pressing rollers 3a, 3b, it is preferable to set the distance W1 from the side edges 51a2, 51b2 of the ceramic green sheets 50 to the inner wall surface 11a of the dam 10a (or the distance W1 from the side edges 51a1, 51b1 to the inner wall surface 11b of the dam 10b) to be large, but in order to increase the yield of the obtained laminated sheet 52, it is desirable to set the distance W1 (see Figure 1) as small as possible.

[0028] In the ceramic green sheet lamination device 1 according to this embodiment, by forming the liquid pool 13, the valley portion V consisting of the multiple ceramic green sheets 50 immediately before being sandwiched between the pressing rollers 3a and 3b is filled with adhesive liquid 53. This eliminates any room for air bubbles to be trapped in this portion, and a laminated sheet 52 without air bubbles existing between the bonding surfaces can be obtained. In contrast, when a lamination device that laminates ceramic green sheets after applying an adhesive liquid as in the past (for example, see Patent Document 1) is used, "air" exists between one ceramic green sheet having a layer of adhesive liquid and the other ceramic green sheet to be laminated just before laminating multiple ceramic green sheets, which inevitably increases the possibility of air bubbles being trapped between these lamination surfaces.

[0029] Furthermore, in the ceramic green sheet lamination apparatus 1 according to this embodiment, even if air bubbles are present in the adhesive liquid 53 forming the liquid puddle 13, the air bubbles (not shown) naturally move toward the liquid surface 8 due to buoyancy. In other words, by forming the liquid pool 13, there is an advantage that air bubbles are efficiently removed from the adhesive liquid 53 present near the bottom position of the valley portion V. Alternatively, even if the air bubbles remain at the bottom position of the valley portion V, that is, at the position where the ceramic green sheet 50 is clamped by the pressing rollers 3a, 3b, since the adhesive liquid 53 is liquid and has fluidity, the air bubbles are squeezed out toward the liquid surface 8 when the ceramic green sheet 50 is clamped by the pair of pressing rollers 3a, 3b, and as a result, it is possible to effectively prevent the air bubbles from becoming trapped between the bonding surfaces of the ceramic green sheet 50.

[0030] Of course, it is preferable that no air bubbles exist in the adhesive liquid 53 forming the liquid pool 13. For this reason, the adhesive liquid supply mechanism 6 of the ceramic green sheet lamination apparatus 1 according to this embodiment may be provided with a degassing means (not shown) for removing air bubbles from the adhesive liquid 53 supplied to the liquid pool 13, as necessary. As described above, according to the ceramic green sheet lamination apparatus 1 of this embodiment, when multiple ceramic green sheets 50a, 50b are sandwiched and pressed by a pair of pressure rollers 3a, 3b to form a stacked state, it is possible to minimize the inclusion of air bubbles together with the adhesive liquid 53 between the bonding surfaces of the ceramic green sheets 50a, 50b.

[0031] In addition, in the ceramic green sheet lamination apparatus 1 according to this embodiment, the adhesive liquid 53 supplied from the adhesive liquid supply mechanism 6 to the valley portion V may be any liquid adhesive used for bonding the ceramic green sheets 50 (e.g., ceramic green sheets 50a, 50b) without any particular restrictions. More preferably, as the adhesive liquid 53, a slurry containing components of the same quality as the solid contents, such as the ceramic powder and the organic binder, constituting the ceramic green sheet 50 can be used.

[0032] In addition, when the ceramic powders constituting each of the laminated ceramic green sheets 50a, 50b are different from each other, a mixed powder of the ceramic powder constituting the ceramic green sheet 50a and the ceramic powder constituting the ceramic green sheet 50b may be used as the ceramic powder constituting the adhesive liquid 53.

[0033] Furthermore, as a solvent for preparing the above-mentioned slurry (adhesive liquid 53), for example, water or an organic solvent is appropriately used. In addition, if the viscosity of the slurry (adhesive liquid 53) is too high, it becomes difficult to supply it between the ceramic green sheets, whereas if it is too low, the adhesiveness of the ceramic green sheets 50 decreases. Therefore, it is preferable to set the viscosity at about 10 to 20,000 cps.

[0034] Then, the above-mentioned slurry is used as the adhesive liquid 53, and after the adhesive liquid 53 is sandwiched between the bonding surfaces of a plurality of ceramic green sheets 50 (e.g., ceramic green sheets 50a, 50b), the adhesive liquid 53 dissolves the surrounding ceramic green sheets 50 to integrate them.

[0035] Then, when the laminated sheet 52 produced by the ceramic green sheet lamination apparatus 1 of this embodiment is fired, a flat ceramic sintered body is obtained that has no voids in its thickness portion due to the entrapment of air bubbles or has very few voids therein. The fact that the ceramic sintered body obtained by firing the laminated sheet 52 does not have any voids or has only a very small number of voids as described above means that the strength and insulating properties of the ceramic sintered body are excellent. Therefore, according to the ceramic green sheet lamination apparatus 1 of this embodiment, it is possible to easily manufacture a laminated sheet 52 that has excellent strength and insulation properties after firing and that can exhibit these characteristics approximately uniformly throughout the entire area in the planar direction of the final product, a flat ceramic sintered body.

[0036] In addition, it is preferable to select a material for the dams 10a, 10b constituting the damming mechanism 9 of the ceramic green sheet lamination apparatus 1 according to this embodiment, such as silicone rubber or Teflon (registered trademark), which has good slipperiness, solvent resistance, and stain resistance.

[0037] Furthermore, in the ceramic green sheet lamination device 1 according to this embodiment, the pair of pressure rollers 3a, 3b may include, for example, cylindrical pressure members 5a, 5b and shafts 4a, 4b whose axes are aligned with each other. The design conditions, such as the material of the pressing members 5a, 5b constituting the pair of pressing rollers 3a, 3b as described above, the distance between the pressing members 5a, 5b, the rotational speed of the pressing members 5a, 5b, and the pressure applied from the pressing members 5a, 5b to the multiple ceramic green sheets 50a, 50b, can be the same as those used in conventionally known rollers for bonding ceramic green sheets, without any particular restrictions. More specifically, the material for the pressing members 5a, 5b (roller body) is preferably one that does not apply excessive pressure to the ceramic green sheet 50 and does not scratch the surface of the ceramic green sheet 50; specifically, rollers made of rubber or silicone can be used.

[0038] The size of the gap between the pair of pressing members 5a, 5b may be appropriately set in consideration of the pressing force, ie, the clamping pressure, to be applied to the ceramic green sheets 50 to be bonded together. In other words, the size of the gap between the pair of pressing members 5a, 5b should be set so that the ceramic green sheet 50 is not crushed and irreversibly deformed when sandwiched between the two pressing members 5a, 5b, and so that a desired amount of adhesive liquid 53 can be uniformly retained between the bonding surfaces of the ceramic green sheet 50.

[0039] More specifically, when the raw material ceramic green sheet 50 itself has poor deformability, the gap between the pair of pressing members 5a, 5b may be set relatively large. Furthermore, if the raw material ceramic green sheet 50 has a certain degree of elasticity and it is desired to form a very thin layer of adhesive liquid 53 between the bonding surfaces of the ceramic green sheet 50, the gap between the pair of pressing members 5a, 5b may be set relatively small. Furthermore, when the clamping pressure (pressing force) acting on the multiple ceramic green sheets 50 from the pair of pressing members 5a, 5b is particularly small, that is, when the pressing members 5a, 5b themselves are made of a material with excellent deformability, such as a foam, the size of the gap between the pair of pressing members 5a, 5b can be set relatively small.

[0040] Furthermore, the pressure applied from the pair of pressing members 5a, 5b (the pair of pressing rollers 3a, 3b) to the stacked ceramic green sheets 50 may be adjusted by installing an elastic material such as a spring or rubber on the shafts 4a, 4b of both pressing rollers 3a, 3b. A method for adjusting the pressing force applied to the ceramic green sheets 50 by the pair of pressing rollers 3a, 3b will be described in detail later with reference to FIG.

[0041] Furthermore, the laminated sheet 52 led out downstream from between the pair of pressing rollers 3a, 3b can be sufficiently bonded by simply drying naturally in the air, for example, indoors. However, depending on the type of solvent (binder) used in the adhesive liquid 53, it is also possible to bond the multiple ceramic green sheets 50 more firmly by forcibly drying the laminated sheet 52 by providing a drying means (drying device) downstream of the pair of pressing rollers 3a, 3b as necessary.

[0042] Next, with reference to Figures 1 and 3 to 8, optional options and modifications that can be added, either alone or in combination with multiple types, as necessary to the basic configuration of the ceramic green sheet lamination device 1 according to the present embodiment will be described.

[0043] [2-1; Positional relationship between the dam and the ceramic green sheet surface] When the above-mentioned slurry is used as the adhesive liquid 53, the adhesive liquid 53 becomes a liquid having a certain degree of viscosity. In this case, a gap may be formed between the lower edges 12a, 12b of the inner wall surfaces 11a, 11b of the weirs 10a, 10b and the surfaces of the ceramic green sheets 50a, 50b forming the valley portion V, to an extent that the liquid sealing properties of the adhesive liquid 53, which is a slurry, can be maintained. In this case, the risk of damage or breakage of the ceramic green sheet 50 just before it is sandwiched between a pair of pressing rollers 3a, 3b can be significantly reduced compared to when the lower edges 12a, 12b of the inner wall surfaces 11a, 11b of the dams 10a, 10b contact the surface of the ceramic green sheet 50. This can significantly reduce the risk of producing defective products when manufacturing the laminated sheet 52. In other words, when the above-mentioned gap is formed between the lower edges 12a, 12b of the inner wall surfaces 11a, 11b of the dams 10a, 10b and the surfaces of the ceramic green sheets 50a, 50b forming the valley portion V, the productivity of the final product, a flat ceramic sintered body, can be improved.

[0044] The size of the gap varies depending on the viscosity of the adhesive liquid 53 used and therefore cannot be generally specified; however, the size can be set larger as the viscosity of the adhesive liquid 53 approaches the upper limit value shown above, and needs to be set smaller as the viscosity of the adhesive liquid 53 approaches the lower limit value shown above. More specifically, for example, when the viscosity of the adhesive liquid 53 is 1000 cps, the size of the gap may be set to about 0.2 mm. The lower edges 12a, 12b of the inner wall surfaces 11a, 11b of the weirs 10a, 10b and the surfaces of the ceramic green sheets 50a, 50b forming the valley portions V do not necessarily have to have the above-mentioned gap, and may be in contact with each other. In this case, it is advisable to take care not to scrape off the surface of the ceramic green sheet 50 in the portions that come into contact with the dams 10a, 10b. More specifically, for example, the lower edges 12a, 12b of the inner wall surfaces 11a, 11b of the weirs 10a, 10b may be made of a soft material, or the lower edges 12a, 12b may have a thin, deformable film-like structure.

[0045] [2-2: Thickness of the ceramic green sheet sandwiched between a pair of pressure rollers] The ceramic green sheets 50 sandwiched between the pair of pressure rollers 3a and 3b according to this embodiment may all have the same thickness or may have different thicknesses. As described above, when the adhesive liquid 53 and the firing conditions are suitable, the ceramic green sheets 50a and 50b may be made of different types of ceramic powder.

[0046] [2-3: Number of ceramic green sheets sandwiched between a pair of pressure rollers] Figures 1 and 2 show an example in which two ceramic green sheets 50a, 50b are sandwiched between a pair of pressing rollers 3a, 3b and stacked to form one laminated sheet 52, but the number of ceramic green sheets 50 sandwiched between the pair of pressing rollers 3a, 3b may be two or more. In this case, the number of valleys V formed varies depending on the number of ceramic green sheets 50 used as the raw material. More specifically, when the number of ceramic green sheets 50 sandwiched between the pair of pressure rollers 3a and 3b is, for example, three, the number of valleys V is two. Similarly, when the number of ceramic green sheets 50 sandwiched between the pair of pressure rollers 3a and 3b is, for example, four, the number of valleys V will be three.

[0047] [2-4; Adhesive supply mechanism] The adhesive liquid supply mechanism 6 may include a liquid level control means 14 for controlling the liquid level of the adhesive liquid 53, as shown in FIG. More specifically, this liquid level control means 14 may be provided with a control unit 18 that stores a target value for the liquid level in the liquid reservoir 13 (storage area), and judges whether the liquid level is appropriate based on liquid level data obtained by a liquid level detection unit 15 such as a sensor (judgment area), and outputs a control signal that controls the opening and closing of the liquid level control valve 16 (valve control area). In other words, in the liquid level control means 14 as described above, for example, when the liquid level in the liquid pool 13 falls below a preset target value, the liquid level control valve 16 is opened and the adhesive liquid 53 is supplied to the liquid pool 13 via the adhesive liquid supply pipe 17 and the supply nozzle 7. On the other hand, when the liquid level in the liquid pool 13 reaches the target value, the liquid level control valve 16 is closed and the supply of the adhesive liquid 53 from the adhesive liquid supply pipe 17 and the supply nozzle 7 to the liquid pool 13 is stopped.

[0048] In this case, the liquid level of the liquid pool 13 formed in the valley portion V can be maintained at a target value or a value close to the target value. In other words, by providing the liquid level control means 14, it is possible to prevent the adhesive liquid 53 from overflowing from the valley portion V and the adhesive liquid 53 forming the liquid pool 13 from drying up. This allows the ceramic green sheet lamination apparatus 1 according to this embodiment to continuously manufacture the laminated sheet 52. As a result, the laminated sheet 52 can be mass-produced efficiently.

[0049] Further, in FIG. 1, the outlet of supply nozzle 7 is separated from liquid surface 8, but the outlet of supply nozzle 7 may be submerged in liquid pool 13. When the outlet of supply nozzle 7 is spaced from liquid level 8, the distance from a preset target value of the liquid level to the outlet of supply nozzle 7 may be set to 5 cm or less, more preferably 2 cm or less. In this case, it is possible to reduce the impact when adhesive liquid 53 is supplied from supply nozzle 7 to puddle 13. This makes it possible to prevent air bubbles from being generated in puddle 13 and to prevent adhesive liquid 53 from scattering around puddle 13. As a result, it is possible to prevent the front and back surfaces of the laminated sheet 52 from being soiled with the adhesive liquid 53 scattered when the laminated sheet 52 is supplied to the liquid pool 13, which would impair the smoothness of the front and back surfaces of the laminated sheet 52 and cause the laminated sheet to become defective.

[0050] Fig. 3 is a schematic diagram of the main part of the ceramic green sheet lamination device according to the present embodiment, which is equipped with a liquid level control means according to a modified example. Note that the same parts as those shown in Fig. 1 or 2 are given the same reference numerals, and the description of their configurations is omitted. The liquid level control means 14 shown in FIG. 1 has been described as an example in which adhesive liquid 53 is supplied from multiple supply nozzles 7 to the liquid pool 13, but the method of supplying adhesive liquid 53 to the liquid pool 13 may be other than that shown in FIG. 1. More specifically, as shown in FIG. 3, for example, the liquid level control means 14′ in the modified example is provided with an adhesive liquid container 39 (adhesive liquid supply mechanism 6′) above the liquid pool 13, and is configured to supply adhesive liquid 53 to this adhesive liquid container 39 via the liquid level control valve 16 and the adhesive liquid supply piping 17, and also to supply adhesive liquid 53 from this adhesive liquid container 39 to the liquid pool 13.

[0051] Moreover, the adhesive liquid container 39 shown in FIG. 3 has at least one adhesive liquid outlet hole (not shown) on the surface facing the liquid surface 8 of the liquid pool 13. Furthermore, the liquid level control means 14' in the modified example may be equipped with a control unit 18' which stores a target value for the liquid level in the liquid pool 13 (storage area), and judges whether the liquid level is appropriate based on liquid level data obtained by a liquid level detection unit 15 such as a sensor (judgment area), and outputs a control signal which controls the opening and closing of the liquid level control valve 16 and / or the adhesive liquid outlet hole (not shown) (liquid level control area). The ceramic green sheet lamination apparatus 1' equipped with the liquid level control means 14' according to the modified example also exerts the same effects as the ceramic green sheet lamination apparatus 1 equipped with the liquid level control means 14 (see FIG. 1).

[0052] [2-5; Regarding lateral resection methods] 4 is a conceptual diagram of a side edge cutting means in a ceramic green sheet lamination device according to this embodiment. Note that the same parts as those shown in Figs. 1 to 3 are given the same reference numerals, and the description of their configurations is omitted. As shown in FIG. 4, the ceramic green sheet lamination apparatus 1 according to this embodiment may include a side edge cutting means 20 that is provided downstream of a pair of pressing rollers 3a, 3b and cuts off areas of a predetermined width on both side edges of the laminated sheet 52. This side edge cutting means 20 includes a pair of disk-shaped cutters 21a, 21b arranged a predetermined width W2 inward from each of the side edges 52a, 52b of the laminated sheet 52, and a shaft 22 that rotatably supports the cutters 21a, 21b while connecting them together.

[0053] When cutting off both side edges 52a, 52b of the laminated sheet 52 using the side edge cutting means 20, cutters 21a, 21b are positioned at a position a predetermined width W2 away from both side edges 52a, 52b of the laminated sheet 52 toward the inside of the laminated sheet 52, and the blades are pressed against the laminated sheet 52 while the end 52c of the laminated sheet 52 is pulled downstream while the shaft 22 is rotated around its axis. As a result, the pair of cutters 21a, 21b rotate counterclockwise (for example, in the direction indicated by symbol B in Figure 4), and a predetermined width region W2 based on both side edges 52a, 52b of the laminated sheet 52 is continuously cut out from the laminated sheet 52.

[0054] Furthermore, the value of the specified width W2 may be set arbitrarily, but it is preferable to set it so that the portions to which adhesive liquid 53 is not supplied (portions to which adhesive liquid 53 is not sandwiched), i.e., the non-adhesive portions of laminated sheet 52, are cut off.

[0055] When the ceramic green sheet lamination apparatus 1 according to this embodiment includes the side edge cutting means 20, a tension control roller 19 may be provided upstream of the installation position of the pair of cutters 21a, 21b, as necessary. In this case, the positional relationship between the pair of cutters 21a, 21b and the laminated sheet 52 can be kept substantially constant, so that the dimensional accuracy of the laminated sheet 52 after cutting can be improved.

[0056] [2-6; Pressure adjustment means] Fig. 5 is a conceptual diagram showing an example of a driving mechanism for a pair of pressing rollers in a ceramic green sheet lamination device according to this embodiment. Note that the same parts as those shown in Figs. 1 to 4 are given the same reference numerals, and the description of their configurations is omitted. The driving means for the pair of pressing rollers 3a, 3b in the ceramic green sheet lamination device 1 according to the present embodiment is not particularly limited, and any known roller driving means can be adopted. As an example of such roller driving means, for example, a motor 28 shown in FIG. 4 may be used. More specifically, a pulley 25 may be provided near the end of the pressing roller 3b in the direction of the rotation axis, and a pulley 26 may also be provided on the rotating shaft 28a of the motor 28 arranged at a position spaced apart from this pulley 25, and the pulleys 25 and 26 may be connected by a circular power transmission belt 27. In this case, the motor 28 rotates the pressure roller 3b counterclockwise around its rotation axis, and in conjunction with this rotation, the pressure roller 3a rotates clockwise around its rotation axis. In the example of the drive mechanism for the pressure rollers 3a and 3b shown in FIG. 5, power transmission means such as gears can be used instead of the pulleys (pulley 25 and pulley 26).

[0057] As shown in FIG. 5, the shaft 4a of the pressure roller 3a is inserted into and supported by an insertion hole 24a formed in a shaft support portion 23a fixed to a horizontal frame 30 arranged in the horizontal direction. Similarly, the shaft 4b of the pressure roller 3b is inserted into an insertion hole 24b formed in a shaft support portion 23b fixed to the horizontal frame 30 and supported therein.

[0058] In order to adjust the pressing force acting on the plurality of ceramic green sheets 50 sandwiched between the pressing rollers 3a and 3b, for example, a tension spring 29 may be installed between the shaft 4a of the pressing roller 3a and the shaft 4b of the pressing roller 3b as shown in Fig. 5. Although not shown, an elastic material such as a circular rubber band may be used instead of the tension spring 29. In this case, the elastic force of the tension spring 29 attracts the shafts 4a and 4b toward each other (see symbol E in Figure 5), thereby increasing the pressing force applied to the multiple ceramic green sheets 50 by the pressing members 5a, 5b (pressing rollers 3a, 3b). In addition, by appropriately changing the elastic force of the tension spring 29 or a rubber band (not shown), the pressing force applied to the multiple ceramic green sheets 50 by the pressing members 5a, 5b (pressing rollers 3a, 3b) can be changed as desired.

[0059] The pressing force adjusting means for adjusting the pressing force acting on the ceramic green sheet 50 sandwiched between the pressing rollers 3a, 3b may be an elastic body other than the above-mentioned tension spring 29 or rubber. More specifically, a hydraulic or air cylinder may be provided on each of both ends of the pressure roller 3a that is not driven by the motor 28, so that the pressure roller 3a can be pressed against the pressure roller 3b with a desired pressing force while keeping the rotational axis of the pressure roller 3a and the rotational axis of the pressure roller 3b approximately parallel to each other. In this case, it is preferable that the pressing roller 3a (its shaft 4a) is supported so as to be slidable in the horizontal direction, and the pressing roller 3b (its shaft 4b) is supported so as not to be slidable in the horizontal direction (not shown).

[0060] Furthermore, when a hydraulic or air cylinder is used as the pressing force adjustment means, a control mechanism is required, which complicates the structure of the ceramic green sheet lamination device 1 in this embodiment, but it becomes possible to adjust with high precision the pressing force acting on the ceramic green sheet 50 sandwiched between a pair of pressing rollers 3a, 3b. In other words, when the thicknesses of the multiple ceramic green sheets 50 used as the raw material are different, or when a prefabricated laminated sheet 52 is used as the raw ceramic green sheet 50 to produce a thicker laminated sheet 52, it becomes easy to change the pressing force acting on the ceramic green sheet 50 as desired. Therefore, when the ceramic green sheet lamination device 1 according to this embodiment is provided with a hydraulic or air cylinder as a pressing force adjustment means, the versatility of the device for the thickness of the ceramic green sheets 50 as raw material can be increased. In other words, it is possible to provide a ceramic green sheet lamination device 1 with higher performance.

[0061] In addition, FIG. 5 illustrates an example in which only the pressing roller 3b of the pair of pressing rollers 3a, 3b is driven by the motor 28, but the pressing rollers 3a, 3b may each be driven by a separate motor, and the rotational operations of both pressing rollers 3a, 3b may be synchronized by a control unit (not shown) that is not shown. In this case, even if the thickness of the adhesive liquid 53 sandwiched between the bonding surfaces of the ceramic green sheets 50 is set relatively large and it is difficult to make one pressing roller 3b follow the other pressing roller 3a, it is possible to manufacture a laminated sheet 52 by the ceramic green sheet lamination apparatus 1 of this embodiment.

[0062] [2-7; How to recover laminated sheets] Fig. 6 is a vertical cross-sectional image diagram of a ceramic green sheet lamination device according to this embodiment. Note that the same parts as those shown in Figs. 1 to 5 are given the same reference numerals, and the description of their configurations will be omitted. As shown in Figure 6, the ceramic green sheet lamination apparatus 1 of this embodiment may be equipped with a support structure consisting of a horizontal frame 30 that directly or indirectly supports a pair of pressure rollers 3a, 3b and their driving mechanisms (not shown) shown in Figure 1 and the like, and a vertical frame 31 that supports this horizontal frame 30. The ceramic green sheet lamination apparatus 1 according to the present embodiment as described above may also be provided with a recovery roller 37 (winding means 34) arranged downstream of the pair of pressure rollers 3a, 3b, as shown in FIG. 6, for winding up and recovering the produced laminated sheet 52. In this case, since the laminated sheet 52 can be wound up and collected by the collection roller 37, the ceramic green sheet lamination device 1 according to this embodiment can be made compact.

[0063] A support frame 35 may be provided separately vertically below the horizontal frame 30, and the collection roller 37 may be provided on this support frame 35. Furthermore, when the ceramic green sheet lamination device 1 according to this embodiment includes the recovery roller 37, a tension control roller 36 may be provided downstream of the pair of pressure rollers 3a, 3b and upstream of the recovery roller 37. In this case, the orientation of the laminated sheet 52 fed out from between the pair of pressure rollers 3a, 3b can be kept constant, so that a homogenized laminated sheet 52 can be efficiently manufactured.

[0064] Furthermore, the ceramic green sheet lamination apparatus 1 according to this embodiment may be provided with supply rollers 32a, 32b that hold the raw ceramic green sheets 50a, 50b in a roll and supply the ceramic green sheets 50a, 50b between a pair of pressing rollers 3a, 3b, as shown in FIG. 6, for example. In this case, the mechanism for feeding the ceramic green sheets 50a, 50b, which are raw materials, between the pair of pressure rollers 3a, 3b can be made compact and simple. If necessary, a tension control roller 33a may be provided between the supply roller 32a and the pressure roller 3a. Similarly, a tension control roller 33a may be provided between the supply roller 32b and the pressure roller 3b. In this case, the orientation of the ceramic green sheets 50a, 50b supplied between the pair of pressure rollers 3a, 3b can be kept substantially constant, so that a more uniform laminated sheet 52 can be efficiently manufactured.

[0065] In addition, when the liquid level in the liquid pool 13 is automatically controlled by the liquid level control means 14 (see Figure 1) or the liquid level control means 14' (see Figure 3) to reach or approximate a target value, the rotational operation of the pair of pressure rollers 3a, 3b and the rotational operation of the recovery roller 37 may be synchronized by a control signal output from the control unit 18 or the control unit 18'. In this case, the production speed of the laminated sheet 52 can be maintained at a desired level, so that homogeneous laminated sheets 52 can be mass-produced efficiently.

[0066] Furthermore, in the ceramic green sheet lamination apparatus 1 according to this embodiment shown in FIG. 6, if the rotational movement of the supply rollers 32a, 32b can be made to follow the rotational movement of the pair of pressure rollers 3a, 3b and the recovery roller 37 by adding a desired resistance to each of the rotational axes of the supply rollers 32a, 32b, there is no particular need to control the rotational movement of the supply rollers 32a, 32b by a control signal output from the control unit 18. Although not shown, in addition to the pair of pressure rollers 3a, 3b and the collection roller 37, the rotational operations of the pair of supply rollers 32a, 32b may also be controlled by a control signal output from the control unit .

[0067] In addition, in FIG. 6, an example is described in which the rotational movement of one of the pair of pressure rollers 3a, 3b (pressure roller 3b) is controlled by a control signal output from the control unit 18, and the other (pressure roller 3a) is caused to follow the one (pressure roller 3b). However, the rotational movements of both pressure rollers 3a, 3b may be individually controlled by control signals output from the control unit 18 (not shown).

[0068] Furthermore, in the ceramic green sheet lamination apparatus 1 according to this embodiment, the rotational operations of the pair of pressure rollers 3a, 3b and the recovery roller 37 may be automatically controlled based on the liquid level in the liquid pool 13. More specifically, for example, the control unit 18 shown in FIG. 6 may be provided with a memory area (not shown) in which a target value for the liquid level in the liquid puddle 13 is stored, a judgment area (not shown) in which the detection value detected by the liquid level detection unit 15 is compared with the target value to judge whether the liquid level in the liquid puddle 13 is appropriate, and a speed change area (not shown) in which, when the judgment area judges that the liquid level in the liquid puddle 13 is insufficient based on the detection value of the liquid level detection unit 15, a speed decrease signal is output to the pair of pressing rollers 3a, 3b and the recovery roller 37 to decrease the production speed of the laminated sheet 52, and, when the judgment area judges that the liquid level in the liquid puddle 13 is sufficient based on the detection value of the liquid level detection unit 15, a speed increase signal is output to the pair of pressing rollers 3a, 3b and the recovery roller 37 to increase the production speed of the laminated sheet 52.

[0069] Furthermore, when the control unit 18 of the ceramic green sheet lamination apparatus 1 in this embodiment is configured as described above, even when the liquid level in the liquid puddle 13 falls below the target value and the situation does not recover, it is possible to suppress the occurrence of problems such as a relatively small amount of adhesive liquid 53 being sandwiched between the bonding surfaces of multiple ceramic green sheets 50 (e.g., ceramic green sheets 50a, 50b) or no adhesive liquid being sandwiched at all. That is, it is possible to prevent as much as possible the laminated sheet 52 produced by the ceramic green sheet lamination apparatus 1 according to this embodiment from becoming a defective product.

[0070] Furthermore, the control unit 18 may be configured so that a lower limit value of the liquid level is further stored in the memory area, and when it is determined in the determination area that the liquid level in the liquid puddle 13 has fallen below the lower limit value by comparing the detection value detected by the liquid level detection unit 15 with the lower limit value, it outputs a stop signal from the speed change area to stop the rotational operation of the pair of pressure rollers 3a, 3b and the recovery roller 37. Note that this lower limit value is an arbitrary value between the deepest position of the valley V and the above target value. In this case, if for some reason the adhesive liquid supply mechanism 6 or 6' is unable to supply the adhesive liquid 53 to the liquid reservoir 13, the operation of the ceramic green sheet lamination device 1 or 1' can be automatically stopped. In this case, it is possible to more reliably prevent the laminated sheet 52 produced from becoming a defective product.

[0071] Furthermore, in the ceramic green sheet lamination apparatus 1 according to this embodiment, if necessary, a sheet-like guide member 38 for guiding the ceramic green sheet 50a may be installed between the pressing roller 3a and the tension control roller 33a, and a sheet-like guide member 38 for guiding the ceramic green sheet 50b may also be installed between the pressing roller 3b and the tension control roller 33b. In this case, it is possible to prevent cracks and the like from occurring in the ceramic green sheets 50a, 50b due to sagging of the ceramic green sheets 50a, 50b fed between the pair of pressure rollers 3a, 3b. In other words, it is possible to minimize the occurrence of defective products in the ceramic green sheets 50 that are the raw material. Although not specifically shown, the same effect can be obtained when a belt conveyor is provided instead of the guide member 38.

[0072] In addition, Figure 6 illustrates an example in which the laminated sheet 52 sent out from a pair of pressure rollers 3a, 3b is wound and recovered by a recovery roller 37 (winding means), but the method of recovering the laminated sheet 52 does not need to be limited to the above. More specifically, the laminated sheet 52 emerging from between the pair of pressure rollers 3a, 3b may be transported further downstream as it is, cut to an appropriate size, and then degreased and fired by a known method to produce a flat ceramic sintered body, which may be subjected to the steps in a continuous manner. In this case, the ceramic green sheet lamination device 1 according to this embodiment constitutes a part of equipment for producing a flat-plate ceramic sintered body.

[0073] [2-8; Variations in the damming mechanism] Fig. 7 is a perspective view showing a modified example of the dam in the ceramic green sheet lamination device according to this embodiment. Also, Fig. 8 is a partial cross-sectional view of the ceramic green sheet lamination device according to this embodiment equipped with the modified dam. Note that the same parts as those shown in Figs. 1 to 6 are given the same reference numerals, and the description of their configurations will be omitted. As shown in Figure 7, the dam 10a (or 10b) of the dam mechanism 9' of the modified example is arranged so as to shield the gap formed between the lower edge 12a (or lower edge 12b) of the dam 10a (or dam 10b) and the surface of the ceramic green sheet 50 when it is provided in a valley V formed between ceramic green sheets 50 (e.g., ceramic green sheets 50a, 50b), and may be provided with a shielding material made of a flexible material. More specifically, as the above-mentioned shielding material, for example, a shielding sheet 40 made of a sheet material made of rubber, silicone or a flexible resin, which is attached to the inner wall surface 11a (or inner wall surface 11b) of the weir 10a (or weir 10b) and has a lower edge 41 that protrudes from the lower edge 12a (or lower edge 12b) of the weir 10a (or weir 10b) toward the surface side of the ceramic green sheet 50 by approximately the same amount as the above-mentioned gap can be used.

[0074] In this case, as shown in FIG. 8, when a modified dam mechanism 9' is provided in a valley portion V formed between ceramic green sheets 50 (e.g., ceramic green sheets 50a, 50b), the gap generated between the dam 10a (or dam 10b) and the ceramic green sheet 50 can be shielded by the protruding portion of the shielding sheet 40. In this case, there is a high possibility that the lower edge 41 of the shielding sheet 40 will come into contact with the surface of the ceramic green sheet 50 immediately before it is sandwiched between the pair of pressure rollers 3a, 3b.

[0075] When the lower edge 41 of the shielding sheet 40 comes into contact with the surface of the ceramic green sheet 50, very shallow streak-like scratches may be caused on the surface of the ceramic green sheet 50; however, because the shielding sheet 40 is made of a sheet material that is flexible and pliable, the raw material ceramic green sheet 50 will not be damaged to the extent that the laminated sheet 52 would be defective. Furthermore, a predetermined width region W2 based on the side edges 52a, 52b is cut out of the laminated sheet 52. Therefore, even if the above-mentioned scratches are made on the bonding surfaces of the multiple ceramic green sheets 50, there is no adverse effect on the final product.

[0076] Therefore, when the damming mechanism 9' of the modified example is used (see Figures 7 and 8), the ability of the dams 10a, 10b to block the adhesive liquid 53 can be improved compared to when the damming mechanism 9 (see Figures 1 and 2, etc.) is used. In this case, since the laminated sheet 52 can be produced using the adhesive liquid 53 having a relatively low viscosity, the versatility of the viscosity of the adhesive liquid 53 of the ceramic green sheet lamination apparatus 1 according to this embodiment can be improved. In other words, it is possible to provide a ceramic green sheet lamination device 1 with higher performance. In addition, the shape of the shielding sheet 40 may be other than that shown in Figures 7 and 8, and for example, it may be a shape in which only the portion corresponding to the protruding portion of the shielding sheet 40 is added (protruded) to the lower edges 12a, 12b of the inner wall surfaces 11a, 11b of the weirs 10a, 10b (not shown). In this case as well, the same effects as those obtained when the shielding sheet 40 shown in FIG. 7 and the like is used can be obtained.

[0077] [2-9; Modifications of ceramic green sheets] In this embodiment, the case where the raw material ceramic green sheets 50 are all single-layer bodies is described as an example, but at least one of the multiple raw material ceramic green sheets 50 may be a laminate (e.g., laminate sheet 52). Furthermore, a laminate sheet 52 produced by the ceramic green sheet lamination apparatus 1 of this embodiment may be used as the raw ceramic green sheet 50, and the gap between a pair of pressure rollers 3a, 3b in the ceramic green sheet lamination apparatus 1 of this embodiment may be adjusted as desired, and the operation of further laminating multiple laminate sheets 52 may be repeated a desired number of times to produce a laminate sheet 52 having a greater thickness.

[0078] [2-10;Other] In the ceramic green sheet lamination apparatus 1 according to this embodiment, it is anticipated that the components of the adhesive liquid 53 supplied from the adhesive liquid supply mechanism 6 may be flammable or contain ingredients that are harmful to the human body. In this case, the ceramic green sheet lamination apparatus 1 shown in FIG. 6 may further include a hood and partition structure for covering the adhesive liquid supply mechanism 6 and the liquid pool 13, and may also include an exhaust means for exhausting gas from within the hood and partition structure (neither is shown). In this case, the laminated sheet 52 can be safely produced by the ceramic green sheet lamination device 1 according to this embodiment.

[0079] In the ceramic green sheet lamination apparatus 1 shown in FIG. 6 above, the ceramic green sheet 50 supplied as a raw material may be provided with a film for forming a smooth surface on the surface forming the front and / or back surface of the laminated sheet 52, i.e., on the surface that is not the bonding surface. In this case, when the raw material ceramic green sheets 50 are sandwiched between the pair of pressure rollers 3a, 3b, the smooth surface forming film may also be sandwiched together. Then, when the ceramic green sheets 50 are pressed by both pressure rollers 3a, 3b to form a laminated sheet 52, the surface provided with the smooth surface forming film is press-molded into a particularly smooth state. As a result, it is possible to produce a high-quality flat ceramic sintered body that has excellent strength and insulating properties after firing and has a smooth front and / or back surface.

[0080] In addition, when the raw ceramic green sheet 50 or the prepared laminated sheet 52 is wound around a roller (e.g., supply rollers 32a, 32b or recovery roller 37) or when they pass through other rollers (e.g., tension control rollers 33a, 33b, pressure rollers 3a, 3b or tension control roller 36), it is advisable to set a minimum value for the diameter of each roller so that cracks or the like do not occur when they come into contact with these rollers and bend. As an example of setting the diameter of each roller, for example, when the thickness of the raw ceramic green sheet 50 does not exceed 1 mm and the number of ceramic green sheets 50 sandwiched between the pressure rollers 3a, 3b is two, the diameter of the supply rollers 32a, 32b can be set to 10 cm or more, the diameter of the pressure rollers 3a, 3b can be set to 5 cm or more, and the diameter of the recovery roller 37 can be set to 20 cm or more.

[0081] [3; Effects of the present invention] The laminated sheet 52 produced by the ceramic green sheet lamination apparatus 1 of this embodiment, or the laminated sheet 52 from which a desired width region W2 has been cut out based on the side edges 52a, 52b, is degreased and fired to produce a flat ceramic sintered body, which is substantially free of air bubbles resulting from air bubbles trapped when multiple ceramic green sheets 50 are laminated together. More specifically, when observing the cross section of a ceramic sintered body obtained by degreasing and firing the laminated sheet 52, it is possible to reduce the number of bubbles of 0.5 mm or more to one in an arbitrarily selected adhesive layer (the portion corresponding to the bonding position) having a total length of approximately 2 m.

[0082] [4; Example] Examples are shown below, but the present invention is not limited to the following examples.

[0083] The ceramic green sheet laminate (Example 1), which is the laminate sheet 52 produced by the ceramic green sheet lamination apparatus 1 according to this embodiment, and the laminate sheet according to Comparative Example 1 produced by another method were evaluated by the following method. In addition, the laminated sheet 52 of Example 1 and the laminated sheet of Comparative Example 1, which were the objects of evaluation, were produced for the purpose of checking the presence and number of air bubbles trapped between the respective bonded surfaces, and therefore, both edges were not cut off.

[0084] (1) Amount of air bubbles in the adhesive layer Ten pieces of about 15 cm square were cut out from the ceramic green sheet laminate (laminate sheet 52 according to Example 1 and laminate sheet according to Comparative Example 1) at random positions, and grooves were cut every 1 cm with a cutter and the pieces were bent and folded to expose the cross section. The adhesive layer of the cross section (part corresponding to the adhesive position) was observed under a microscope, and the number of bubbles of 0.5 mm or more was counted over a total length of 1.96 m.

[0085] (2) Observation of the surface after lamination The presence or absence (cleanliness) of adhesive liquid on both surfaces of the ceramic green sheet laminate (the laminate sheet 52 according to Example 1 and the laminate sheet according to Comparative Example 1) was confirmed.

[0086] (3) Thickness accuracy For the ceramic green sheet laminates (laminate sheet 52 of Example 1 and laminate sheet of Comparative Example 1), the difference between the maximum thickness and the minimum thickness of 15 cm square samples cut at random was measured and shown as the thickness precision.

[0087] [Example 1] (Preparation of Aluminum Nitride Slurry) Aluminum nitride powder (Tokuyama Corporation) 100 parts by mass, yttrium oxide (Japan Yttrium Co., Ltd.) 5 parts by mass, polyvinyl butyral resin (Sekisui Chemical Co., Ltd.) 8 parts by mass as a binder resin, and a small amount of plasticizer were mixed with an organic solvent to obtain an aluminum nitride slurry (viscosity 1000 cps) for molding. (Preparation of Aluminum Nitride Green Sheets) The aluminum nitride slurry for molding was vacuum degassed and viscosity adjusted, then molded into a sheet by a doctor blade method using a sheet molding machine (manufactured by Tester Sangyo Co., Ltd.), and then dried to obtain an aluminum nitride green sheet with a thickness of 0.7 mm. The aluminum nitride green sheet was wound on a roll with a diameter of 20 cm.

[0088] (Lamination of green sheets) A roll on which two aluminum nitride green sheets obtained by the above method were wound was prepared, and as shown in FIG. 6, the two rubber rollers (pressure rollers 3a, 3b) facing each other horizontally and rotating downwards were sandwiched with the bonded surfaces facing inward. The rubber rollers were spring-loaded (tension spring 29; see FIG. 5) and the pressure between the rubber rollers was set to 200 gf. After that, a pair of weirs (weirs 10a, 10b; see FIG. 1) made of silicone rubber were provided on both side edges (1 cm inward from both side edges of the green sheet) of a valley portion (valley portion V; see FIG. 1 and FIG. 2) formed by the aluminum nitride green sheet, with a gap of about 0.2 mm from the surface of the green sheet, and an adhesive liquid (adhesive liquid 53) having the same composition as the slurry used in the production of the aluminum nitride green sheet was supplied to the valley portion to form a liquid pool (liquid pool 13; see FIG. 1). Thereafter, the rubber rollers (pressing rollers 3a, 3b) were driven by a motor (motor 28; see FIG. 5) to adjust the feed speed of the sheets (ceramic green sheets 50a, 50b) to 60 cm / min, the rubber rollers (pressing rollers 3a, 3b) were rotated, and the aluminum nitride green sheet laminate sent out downstream from between the two rubber rollers was taken up. During the above operation, the liquid level (liquid level 8) of the adhesive liquid (adhesive liquid 53) was detected by a sensor (liquid level detection unit 15), and the adhesive liquid (adhesive liquid 53) was supplied in accordance with the drop in the liquid level.

[0089] (evaluation) The thickness of the obtained aluminum nitride green sheet laminate was 1.4 mm, and the thickness precision was 15 μm. The amount of air bubbles present on the bonding surface (between the lamination surfaces) was 0. The surface of the green sheet laminate was clean, with no adhesive liquid adhering thereto.

[0090] (Firing) The green sheet laminate obtained by the above procedure was cut into a 15 cm square, degreased, and then fired in a nitrogen atmosphere at 1750°C for 8 hours to obtain a ceramic sintered body with a thickness of 1.2 mm. The obtained ceramic sintered body was integrated to such an extent that the adhesive portion (lamination portion) was not visible, and no air bubbles were observed in the area corresponding to the adhesive layer (between the lamination surfaces).

[0091] [Comparative Example 1] In the apparatus for producing the green sheet laminate of Example 1, the rotation axes of a pair of rubber rollers corresponding to the pair of pressure rollers 3a, 3b were arranged vertically, and an aluminum nitride green sheet (ceramic green sheet 50a, 50b) wound on a roll was supplied between the rubber rollers with its planar direction arranged vertically, and an adhesive liquid (adhesive liquid 53) was applied to a thickness of 30 μm by a coater on the surface of the aluminum nitride green sheet that would form the lower layer after lamination, while the aluminum nitride green sheet was supplied between the pair of rubber rollers. An aluminum nitride green sheet laminate of Comparative Example 1 was produced in the same manner as in Example 1 above.

[0092] (evaluation) The thickness of the obtained aluminum nitride green sheet laminate according to Comparative Example 1 was 1.4 mm, and the thickness precision was 46 μm. The number of bubbles present on the bonding surface (lamination surface) was 3. The adhesive liquid (adhesive liquid 53) was attached to the surface of the laminate. If the adhesive liquid (adhesive liquid 53) gets onto the surface of the laminate, it will be burned after firing, causing product defects. [Industrial Applicability]

[0093] As described above, the present invention is a ceramic green sheet lamination device that can efficiently mass-produce laminated sheets that have excellent strength and insulation properties after sintering and that can exhibit these properties approximately uniformly throughout the entire area in the planar direction of the final product, a flat-plate-shaped ceramic sintered body, and can be used in technical fields related to electronic components such as electric railway control system boards having ceramic sintered bodies. [Explanation of symbols]

[0094] 1, 1': Ceramic green sheet lamination device 2: Sheet pressing mechanism 3a, 3b: Pressure rollers 4a, 4b: Shafts 5a, 5b: Pressing members 6, 6': Adhesive liquid supply mechanism 7: Supply nozzle 8: Liquid surface (liquid level) 9, 9': Weiring mechanism 10a, 10b: Weirs 11a, 11b: Inner wall surfaces 12a, 12b: Lower edges 13: Liquid pools 14, 14': Liquid level control means 15: Liquid level detection section 16: Liquid level control valve 17: Adhesive liquid supply pipe 18, 18': Control section 19: Tension control roller 20: Side edge cutting means 21a, 21b: Cutter 22: Shafts 23a, 23b: Shaft supports 24a, 24b: Insertion holes 25: Pulleys 26: Pulleys 27: Power transmission belt 28... Motor 28a... Rotating shaft 29... Tension spring (pressure adjustment means) 30... Horizontal frame 31... Vertical frame 32a, 32b... Supply rollers 33a, 33b... Tension control rollers 34... Winding means 35... Support frame 36... Tension control roller 37... Recovery roller 38... Guide member 39... Adhesive liquid storage section 40... Shielding sheet 41... Lower edge 50, 50a, 50b... Ceramic green sheet 51a1, 51a2, 51b1, 51b2... Side edge 52... Laminated sheet 52a, 52b... Side edge 52a', 52b'... Side edge 52c... End 53... Adhesive liquid V... Valley portion W1... Inner wall surface position W2... Removal area

Claims

1. An apparatus for laminating a plurality of ceramic green sheets into a laminated sheet using an adhesive liquid, a sheet pressing mechanism for sandwiching and pressing a plurality of the ceramic green sheets between a pair of pressing rollers provided opposite to each other in a horizontal direction from above the pair of pressing rollers and passing the sheets in a stacked state; an adhesive liquid supplying mechanism for supplying the adhesive liquid to a valley formed between the ceramic green sheets immediately before the ceramic green sheets are sandwiched between the pressing rollers; a damming mechanism that provides a pair of dams whose inner wall surfaces are located inside each of the side edges of the ceramic green sheets that form the valley portions, and that blocks the adhesive liquid supplied from the adhesive liquid supply mechanism between the dams to form a liquid pool.

2. 2. The apparatus for laminating ceramic green sheets according to claim 1, wherein the adhesive liquid supply mechanism includes a liquid level control means for controlling a liquid level in the liquid pool.

3. 3. The ceramic green sheet lamination device according to claim 1, further comprising side edge cutting means provided downstream of the pair of pressure rollers for cutting off areas of a predetermined width on both side edges of the laminated sheet.

4. 3. The ceramic green sheet lamination device according to claim 1, wherein a gap capable of maintaining liquid sealing properties of the adhesive liquid is formed between a lower edge of the inner wall surface of the dam and a surface of the ceramic green sheet forming the valley portion.

5. 3. The ceramic green sheet lamination device according to claim 1, further comprising a pressure adjusting means for adjusting the pressure applied by the pressure rollers to the overlapping portions of the plurality of ceramic green sheets.

6. 3. The ceramic green sheet lamination device according to claim 1, further comprising a winding means provided downstream of the pair of pressure rollers for winding up the laminated sheet.

Images