JP2013086286A - Method and device for manufacturing ceramic green sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device for manufacturing a ceramic green sheet capable of suppressing a phenomenon in which an open face and an outer peripheral part of slurry applied on a base material are dried preferentially and eliminating the necessity of complicated control of drying temperature distribution and an atmosphere.SOLUTION: The method of manufacturing the ceramic green sheet includes: a slurry formation process of forming a flat coating film layer 1 by applying the slurry mixedly including inorganic powder, an organic binder and a volatile dispersion medium on the sheet-shaped base material; a drying process of evaporating the volatile dispersion medium of the slurry within a drying furnace 27 and removing the volatile dispersion medium, after the slurry formation process is performed; and a peeling process of peeling the slurry from the base material, after the drying process is performed. In the slurry formation process, a region in which thickness is reduced at predetermined intervals is provided in the coating layer 1, and in the drying process, a means for controlling removal speed of the volatile dispersion medium within the drying furnace 27 is provided.

Description

  The present invention relates to a method and an apparatus for manufacturing a ceramic green sheet used for manufacturing an electronic component.

  In recent years, there has been an increasing demand for downsizing, weight reduction, and cost reduction of electronic components such as inductors, capacitors, and impedance elements manufactured using ceramic green sheets (hereinafter referred to as green sheets).

  The green sheet is cut or divided into a desired shape as necessary, and then fired to form an electronic component, but there are various types such as a thin film and a thick film depending on the application. It is required to have a high quality without defects such as cracks, cracks, warpage, and internal vacancies.

  A green sheet is a coating film in which a slurry obtained by uniformly stirring and mixing a ceramic raw material powder of an inorganic powder, an organic binder, and a volatile dispersion medium is applied on a substrate typified by polyethylene terephthalate to a desired thickness. After forming the layer, it is obtained by removing the volatile dispersion medium by drying. In this process, the volume of the volatile dispersion medium in the slurry is gradually reduced with drying. As a result, at the end of drying, a uniform and dense green sheet in which the organic binder and the ceramic raw material powder are bonded to each other is obtained. Thus, since the green sheet has uniformity and density reflecting the homogeneity of the slurry, there is an advantage that the ceramic obtained by firing the green sheet can have a homogeneous structure.

  However, in the process of removing the volatile dispersion medium from the coating layer on the substrate by drying, drying proceeds preferentially from the open surface on the side opposite to the substrate. There is a problem that a difference occurs in the degree of densification of the ceramic raw material powder in the green sheet. At the same time, since the drying of the coating layer proceeds preferentially from the outer peripheral portion in the coating layer region, for example, both the outer peripheral portion and the central portion in the width direction of the coating layer width direction applied on the substrate in a band shape There is a problem that a difference occurs in the degree of densification of the ceramic raw material powder in the green sheet. As described above, when the degree of densification of the ceramic raw material powder in the green sheet varies depending on the location in the green sheet, the fired ceramic is likely to be warped and cracked, resulting in quality deterioration.

  In the drying process of the volatile dispersion medium, when the outer peripheral portion of the coating layer on the substrate is preferentially dried, the coating on the substrate is started when the outer peripheral portion is fixed on the substrate and starts shrinking. Since the central portion of the membrane layer is undried and remains fluid, the slurry in the central portion tends to move so as to be dragged by the outer peripheral portion. For this reason, it becomes easy to produce a crack in the green sheet after drying, and brings about deterioration of quality.

  Furthermore, there is a correlation between the frequency of occurrence of cracks in the green sheet and the molding thickness, and as the thickness increases, cracks tend to occur.

  Conventionally, such problems have been dealt with as follows. In patent document 1, it comprised so that the drying heating amount of the coating-film layer width direction center part apply | coated continuously on the base material on the base material might be relatively larger than the drying heating amount of the width direction both outer peripheral part. By using a drying device, the tendency of the coating layer to originally dry preferentially from both outer peripheral portions in the width direction has been alleviated.

  Further, Patent Document 2 discloses a technique in which a volatile dispersion medium is introduced into a green sheet drying zone by bubbling to suppress preferential drying of the coating layer open surface and the outer peripheral portion.

  Moreover, in patent document 3, the airflow which performs drying is made to flow toward the direction opposite to the direction which a base material moves, and by making a green sheet drying temperature so high that it goes to the direction where a base material moves, A technique is disclosed in which the content of the volatile dispersion medium in the air stream to be dried is increased in the initial stage of drying to prevent the green sheet surface from being preferentially dried in the initial stage of drying.

  Furthermore, Patent Document 4 discloses a technique in which a slurry is applied on a peelable film on a resistance heating layer, and the resistance heating layer is heated to dry.

JP 2005-271366 A JP-A-5-301205 JP 2004-90466 A JP 2010-269486 A

  However, in the dry heating method as disclosed in Patent Document 1, since a change in the heating amount that is discontinuous in the width direction is likely to occur, stripes and streaks corresponding to positions at which the heating amount changes are formed on the dried green sheet. Another problem is that it is difficult to control the temperature distribution in the width direction. Even with the mechanism for reducing the non-uniformity of drying as in Patent Document 2, there still remains a problem that the coating layer open surface and the outer peripheral portion are preferentially dried. Further, in Patent Document 3, it is difficult to actively and stably control the content of the volatile dispersion medium, and even with such a mechanism for alleviating drying non-uniformity, the coating film still remains. There has been a problem that a phenomenon occurs in which the layer open surface and the outer peripheral portion are preferentially dried. In patent document 4, since it dried by heat_generation | fever of a resistance heating layer, there existed a problem that the structure of a manufacturing apparatus became complicated.

  Furthermore, in the manufacturing method of the green sheet obtained by drying the coating layer on the substrate, the drying process on the coating layer substrate side and the open surface opposite to the substrate is completely completed. It is virtually impossible to make them identical. In most cases, the green sheet after drying tends to warp so as to be concave toward the open surface opposite to the substrate. In addition, even when a flat green sheet is obtained after drying, in most cases, the filling rate of the ceramic powder is relatively reduced near the surface on the open surface side of the green sheet. For the above two reasons, the ceramic obtained by firing the green sheet has a tendency to warp in a concave direction toward the open surface opposite to the base material when the green sheet is dried. It was difficult.

  Therefore, when realizing these conventional techniques, it has been difficult to actively and stably control the temperature and humidity during drying of the coating layer. Therefore, the effect of suppressing cracking of the green sheet is not sufficient, and cracks are likely to occur at the center of the green sheet, especially there is a correlation with the slurry molding thickness, and as the thickness increases, cracks tend to occur more easily. there were. When cracks occurred, the yield was significantly reduced. Further, the effect of reducing warpage of the ceramic sheet after firing the green sheet was not sufficient.

  Therefore, in the present invention, a method for producing a ceramic green sheet that can suppress the phenomenon of preferential drying of the coating layer open surface and the outer peripheral portion on the substrate and does not require complicated drying temperature distribution and control of the atmosphere. And it aims at providing a manufacturing apparatus.

  In order to solve the above-mentioned problems, the present invention provides a removal rate of the volatile dispersion medium in the drying furnace in the drying process by providing a region where the thickness is reduced at a predetermined interval in the coating film layer in the slurry forming process. Or a means for adjusting the removal rate of the volatile dispersion medium in the drying furnace by providing a drying prevention member at a predetermined interval on the coating layer surface in the slurry forming step. Is. Furthermore, the slurry is applied on a sheet-like base material having portions having different peel strengths, and means for adjusting the removal rate of the volatile dispersion medium in the drying furnace in the drying step is provided.

  That is, according to the present invention, a slurry molding step of forming a flat coating layer by applying a slurry obtained by mixing an inorganic powder, an organic binder, and a volatile dispersion medium onto a sheet-like base material, Production of a ceramic green sheet having a drying step of evaporating and removing the volatile dispersion medium of the slurry in a drying furnace after the slurry forming step, and a peeling step of peeling the slurry from the substrate after the drying step In the slurry forming step, a region having a thickness reduced at predetermined intervals is provided in the slurry forming step, and in the drying step, the removal rate of the volatile dispersion medium in the drying furnace is set. A method for producing a ceramic green sheet characterized in that means for adjusting is provided.

  Moreover, according to the present invention, a slurry molding step of forming a flat coating layer by applying a slurry obtained by mixing an inorganic powder, an organic binder, and a volatile dispersion medium on a sheet-like base material, Production of a ceramic green sheet having a drying step of evaporating and removing the volatile dispersion medium of the slurry in a drying furnace after the slurry forming step, and a peeling step of peeling the slurry from the substrate after the drying step In the slurry forming step, a drying preventing member is disposed at a predetermined interval on the coating layer surface, and in the drying step, the removal rate of the volatile dispersion medium in the drying furnace is adjusted. Thus, a method for producing a ceramic green sheet, characterized in that means for providing the same is provided, is obtained.

  Further, according to the present invention, a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed is applied onto a sheet-like substrate having portions having different peel strengths to form a flat coating layer. A slurry forming step to be formed, a drying step for adjusting the removal rate of the volatile dispersion medium of the slurry in a drying furnace after the slurry forming step, evaporating and removing the slurry, and the step after the drying step A method for producing a ceramic green sheet comprising a peeling step of peeling the slurry from the substrate is obtained.

  Further, according to the present invention, the base material is composed of two members, and a sheet-like second member having a portion punched into a rectangle at a predetermined interval is stacked on the sheet-like first member. It is possible to obtain the above-described method for producing a ceramic green sheet characterized by being configured together.

  Moreover, according to this invention, the peeling strength of said 1st member is higher than the peeling strength of said 2nd member, The said manufacturing method of the ceramic green sheet characterized by the above-mentioned is obtained.

  Further, according to the present invention, the means for adjusting the removal rate includes a first opening through which the volatile dispersion medium evaporated on at least one surface passes, and the base material on which the coating layer is formed includes The ceramic green sheet as described above, wherein the ceramic green sheet comprises a housing having second and third openings passing therethrough, and a removal speed adjusting member is attached to the first opening having a predetermined opening ratio. The manufacturing method is obtained.

  Further, according to the present invention, there is obtained the method for producing a ceramic green sheet, wherein the first opening has an opening ratio of 20% or more and 50% or less.

  Moreover, according to the present invention, the removal speed adjusting member is a wire mesh having a mesh size of # 200 mesh (mesh opening = 0.075 mm) or less and 10 mesh (mesh opening = 1.70 mm) or more. The method for producing the ceramic green sheet is obtained.

  Moreover, according to this invention, in the said slurry formation process, the maximum thickness of slurry formation thickness is 0.3 mm or more and 1.5 mm or less, The said manufacturing method of the ceramic green sheet characterized by the above-mentioned is obtained.

  Moreover, according to this invention, in the said slurry shaping | molding process, the level | step difference of the direction orthogonal to the direction of application | coating is provided in the surface of the said coating-film layer, The said manufacturing method of the ceramic green sheet characterized by the above-mentioned is obtained.

  Moreover, according to this invention, the maximum thickness of the said coating-film layer is 2 times or less of the minimum thickness of the said coating-film layer, The said manufacturing method of the ceramic green sheet characterized by the above-mentioned is obtained.

  Moreover, according to the present invention, a slurry molding unit that forms a flat coating layer by applying a slurry obtained by mixing an inorganic powder, an organic binder, and a volatile dispersion medium onto a sheet-like base material, An apparatus for producing a ceramic green sheet having a drying furnace for evaporating and removing the volatile dispersion medium of the slurry after the slurry forming part, and a peeling part for peeling the slurry from the substrate after the drying furnace. The slurry forming section includes a means for adjusting the removal rate of the volatile dispersion medium in the drying furnace by providing a region where the thickness is reduced at a predetermined interval in the coating layer. A ceramic green sheet manufacturing apparatus is obtained.

  Moreover, according to the present invention, a slurry molding unit that forms a flat coating layer by applying a slurry obtained by mixing an inorganic powder, an organic binder, and a volatile dispersion medium onto a sheet-like base material, An apparatus for producing a ceramic green sheet having a drying furnace for evaporating and removing the volatile dispersion medium of the slurry after the slurry forming part, and a peeling part for peeling the slurry from the substrate after the drying furnace. The slurry forming section includes means for adjusting a removal rate of the volatile dispersion medium in the drying furnace by disposing a drying prevention member at a predetermined interval on the coating layer surface. An apparatus for producing a ceramic green sheet is obtained.

  Moreover, according to the present invention, a slurry molding unit that forms a flat coating layer by applying a slurry obtained by mixing an inorganic powder, an organic binder, and a volatile dispersion medium onto a sheet-like base material, An apparatus for producing a ceramic green sheet having a drying furnace for evaporating and removing the volatile dispersion medium of the slurry after the slurry forming part, and a peeling part for peeling the slurry from the substrate after the drying furnace. The slurry forming unit includes a mechanism for superimposing two sheet-like members as the base material, and means for adjusting a removal rate of the volatile dispersion medium in the drying furnace. An apparatus for producing a ceramic green sheet is obtained.

  Further, according to the present invention, the means for adjusting the removal rate includes a first opening through which the volatile dispersion medium evaporated on at least one surface passes, and the base material on which the coating layer is formed includes A housing having second and third openings passing therethrough is disposed in the drying furnace, and a removal speed adjusting member having a predetermined opening ratio is attached to the first opening. The above-described ceramic green sheet manufacturing apparatus is obtained.

  Further, according to the present invention, there can be obtained the ceramic green sheet manufacturing apparatus, wherein the first opening has an opening ratio of 20% or more and 50% or less.

  Moreover, according to the present invention, the removal speed adjusting member is a wire mesh having a mesh size of # 200 mesh (mesh opening = 0.075 mm) or less and 10 mesh (mesh opening = 1.70 mm) or more. The above-described ceramic green sheet manufacturing apparatus is obtained.

  Further, according to the present invention, in the slurry forming step, the maximum thickness of the slurry forming thickness is 0.3 mm or more and 1.5 mm or less, and the above-described ceramic green sheet manufacturing apparatus is obtained.

  According to the present invention, in the slurry forming step, the ceramic green sheet manufacturing apparatus described above is characterized in that a step in a direction orthogonal to the direction of application is provided on the surface of the coating layer.

  According to the present invention, there is provided the above-mentioned ceramic green sheet manufacturing apparatus, wherein the maximum thickness of the coating layer is not more than twice the minimum thickness of the coating layer.

  According to the present invention, the phenomenon of preferential drying of the coating layer open surface and the outer peripheral portion on the substrate can be suppressed, and it is not necessary to control complicated drying temperature distribution and atmosphere, and cracks, cracks and deformation A high-quality green sheet with less content can be obtained. In addition, according to the present invention, by firing the green sheet, it is possible to provide a high-quality ceramic sheet with less deformation and warping after firing. The effects of these inventions will be described in more detail below.

  In the present invention, the coating layer is formed in a rectangular shape by providing a region where the thickness is reduced at a predetermined interval or by disposing a drying prevention member at a predetermined interval on the surface of the coating layer. The central part of the film layer and the area where the thickness is reduced and the part where the anti-drying member is arranged are dried at different speeds. As a result, in the movement of the slurry during drying shrinkage of the coating layer on the substrate surface, the slurry at the central portion of the coating layer formed in a rectangular shape tends to be attracted uniformly. For this reason, even if the green sheet obtained by drying the coating layer on the base material is cracked, it occurs at a predetermined location and does not crack at the center of the green sheet.

  Further, by forming a base material formed by superposing a second member having peel strength having a portion punched into a square at a predetermined interval on the first member having peel strength of the present invention, The central part of the coating film layer formed on is dried preferentially. Preferably, the peel strength of the first member is different from the peel strength of the second member, and the peel strength of the first member is higher than the peel strength of the second member. As a result, in the movement of the slurry during the drying shrinkage of the coating layer on the substrate surface, a member disposed in the central portion having a high peel strength and a member disposed in the outer peripheral portion having a low peel strength were also formed. The slurry of the outer peripheral portion tends to be attracted uniformly to the central portion of the coating layer. In addition, the coating layer on the outer peripheral portion on the base material having low peel strength due to drying shrinkage tends to maintain a fixed state, but is pulled to cause stress, thereby forming a step or a crack. For this reason, in the green sheet obtained by drying the coating layer on the substrate, even if cracks occur, it occurs at the boundary between a member having a high peel strength and a member having a low peel strength. No longer cracks.

  Furthermore, since the volatile dispersion medium evaporated from the coating layer remains in the vicinity of the coating layer by installing the casing for the purpose of suppressing drying of the present invention in the drying furnace, the atmosphere around the coating layer The concentration of the volatile dispersion medium in the inside can be increased. As a result, the difference in the degree of drying between the inside and the surface of the formed coating layer is reduced, and in the green sheet obtained by drying the coating layer, the densification of the substrate surface side and the open surface side The difference in degree can be reduced. Thereby, the curvature of the ceramic sheet obtained by baking a green sheet can be reduced.

  Conventionally, in order to increase the concentration of the volatile dispersion medium around the slurry drying zone, equipment such as bubbling was required in the green sheet manufacturing apparatus, but according to the configuration of the present invention, such equipment is required. do not do.

  Moreover, the coating film layer on a base material is enclosed in the housing | casing aiming at drying control in a drying furnace, and a coating-film layer center part dries first by providing an opening part in a housing | casing upper part. Therefore, it is possible to more reliably prevent the outer peripheral portion from sticking to the base material, and when the slurry of the outer peripheral portion is attracted to the central portion of the coating layer, cracks tend to occur in the outer peripheral portion of the coating layer. Can be suppressed. Furthermore, in order to obtain a final product ceramic sheet without processing, even when a green sheet is produced by providing a step on the surface of the coating layer, the generation of cracks is eliminated, and the number of man-hours and costs can be reduced. .

  Conventionally, the outer peripheral portion of the coating film layer is dried first, so that a difference occurs in the film thickness between the outer peripheral portion and the central portion. In the present invention, since the central portion and the outer peripheral portion of the coating layer are uniformly dried and contracted, the variation in film thickness can be improved.

  In addition, as a result of increasing the concentration of the volatile dispersion medium in the drying furnace atmosphere, the difference in the degree of densification between the substrate surface side and the open surface side of the green sheet can be further reduced. The warp of the ceramic sheet obtained by firing the sheet is further reduced.

  By the way, conventionally, when using a method of forming a coating layer on a substrate and drying, the ceramic sheet obtained by firing the green sheet is concave toward the open surface opposite to the substrate when the green sheet is dried. There is a tendency to warp. This is because in most cases, the filling rate of the ceramic powder is relatively reduced near the surface of the open side of the green sheet. Even when a flat green sheet is obtained after drying, since the relative reduction in the filling rate of the ceramic powder is inherent, in the ceramic sheet obtained by firing the green sheet, when the green sheet is dried It was extremely difficult to avoid the tendency to warp in the direction of becoming concave toward the open surface opposite to the base material.

  Here, the green sheet manufactured using the manufacturing apparatus of this invention can be made into the shape which becomes convex toward an open surface after drying. The curvature when the green sheet after drying becomes convex toward the open surface is a condition that the rate at which the volatile dispersion medium evaporates becomes slower, that is, the lower the drying temperature or the atmosphere around the coating layer. The higher the concentration of the volatile dispersion medium in, the stronger.

  As described above, in the present invention, the dried green sheet can be formed in a convex shape toward the open surface, and the convex curvature can be controlled. By canceling out this property and the property that the fired ceramic sheet warps into a shape that is concave on the open surface side, a ceramic sheet can be obtained by firing a green sheet having a high degree of flatness.

  As a result, in the ceramic sheet obtained by firing the green sheet, it is possible to obtain a ceramic sheet in which warpage after firing is significantly smaller than that in the past and cracks are unlikely to occur.

The figure which shows the coating film layer which formed the slurry by this invention in the rectangular shape on the sheet-like base material at the predetermined space | interval, FIG. 1 (a) is a perspective view, FIG.1 (b) is AA sectional drawing. . The figure which shows the coating film layer which provided the perpendicular | vertical groove | channel in the longitudinal direction of the sheet-like base material in the longitudinal direction of the slurry by this invention, and formed the level | step difference, Fig.2 (a) is a perspective view, FIG.2 (b) BB sectional drawing. The figure which shows the coating film layer which arrange | positioned the drying prevention member by the predetermined space | interval on the coating film layer surface which formed the slurry by this invention in the rectangular shape on the sheet-like base material, FIG.3 (a) is a perspective view, FIG. 3 (b) is a cross-sectional view taken along the line CC. Explanatory drawing which shows the slurry shaping | molding part by the doctor blade apparatus used for manufacture of the green sheet which provided the perpendicular | vertical groove | channel at the predetermined direction in the longitudinal direction of the sheet-like base material by this invention, and formed the level | step difference. The figure which shows the coating-film layer formed in the base material which overlap | superposed and comprised the 2nd member which has the part which punched the slurry by this invention on the 1st member at the predetermined space | interval in the square, FIG. ) Is a perspective view, and FIG. 5B is a DD cross-sectional view. The figure which shows the base material which overlap | superposed and configured the 2nd member which has the part pierced squarely by the predetermined space | interval on the 1st member by this invention. According to the doctor blade apparatus used for the production of a green sheet formed on a base material formed by superposing a second member having a portion obtained by punching the slurry according to the present invention into a square at a predetermined interval on the first member. Explanatory drawing which shows a slurry shaping | molding part. The block diagram of the drying furnace used for manufacture of the green sheet by this invention. FIG. 9A is a schematic diagram of the upper part of the drying-suppressing casing used for manufacturing the green sheet according to the present invention, FIG. 9A is a schematic diagram of the opening ratio of the first opening at the upper part of the casing, and FIG. 9B. Is a schematic diagram in which the opening ratio of the first opening at the top of the housing is 60%. The block diagram of the doctor blade used for manufacture of the green sheet by this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The ceramic slurry is obtained by the following process. Pure water is used as the volatile dispersion medium. After determining the mass of the ceramic raw material powder of the inorganic powder as the main raw material, an acrylic binder, urethane-modified polyether and polycarboxylic acid ammonium salt obtained by copolymerizing a predetermined acrylic acid, acrylic ester and nonionic acrylate Then, a polyethylene glycol type nonionic surfactant and pure water are mixed to obtain an aqueous binder solution.

  Thereafter, a desired ceramic slurry is obtained by adding the binder aqueous solution to the ceramic raw material powder having the determined mass and mixing and stirring in a mixer capable of creating a reduced pressure atmosphere. The reduced pressure atmosphere is preferably 5 kPa or more and 10 kPa or less. Moreover, as a mixer, a planetary mixer, a kneader, a ball mill, a homogenizer, etc. can be used.

  As an acrylic binder, what copolymerized acrylic acid, acrylic ester, and nonionic acrylate is preferable, and as addition amount, they are 2.0 mass% or more and 25.0 mass% or less with respect to the mass of ceramic raw material powder. Within the range is preferable.

  The addition amount of the urethane-modified polyether is preferably in the range of 0.1% by mass to 15.0% by mass with respect to the mass of the ceramic raw material powder.

  The addition amount of the ammonium salt of the polycarboxylic acid polymer is preferably in the range of 0.2% by mass or more and 8.0% by mass or less with respect to the mass of the ceramic raw material powder.

  The addition amount of the polyethylene glycol type nonionic surfactant is preferably in the range of 0.01% by mass to 5.00% by mass with respect to the mass of the ceramic raw material powder. Further, the amount of pure water added is preferably in the range of 10% by mass to 30% by mass.

  The coating film layer which apply | coated the slurry on the base material is demonstrated. FIG. 1 is a view showing a coating layer in which a slurry according to the present invention is formed in a rectangular shape on a sheet-like base material at predetermined intervals, FIG. 1 (a) is a perspective view, and FIG. It is -A sectional drawing. FIG. 2 is a diagram showing a coating layer in which the slurry according to the present invention is provided with vertical grooves at predetermined intervals in the longitudinal direction of the sheet-like base material, and FIG. 2 (a) is a perspective view. 2 (b) is a BB cross-sectional view. FIG. 3 is a view showing a coating layer in which the anti-drying member is arranged at predetermined intervals on the coating layer surface in which the slurry according to the present invention is formed in a rectangular shape on a sheet-like substrate, and FIG. A perspective view and FIG.3 (b) are CC sectional drawing.

  As a method of forming a coating film layer on a substrate as shown in FIG. 1, from a die having a width of 200 mm in which the opening height of the slurry discharge port is adjusted to 1 mm so as to obtain a desired slurry coating film thickness, The slurry is discharged intermittently and applied onto the substrate 2 so that the slurry application portion is a single square having a side of 200 mm. Such a slurry application method is also called a die slot method. By this method, as shown in FIG. 1, the coating layer 1 is formed at predetermined intervals with the slurry in a rectangular shape on a sheet-like substrate.

  Moreover, as shown in FIG. 2, after adjusting the coating width to 200 mm by a doctor blade method and continuously forming into a sheet shape, the slurry applied to the base material 2 was processed into a linear opening in a hollow bar. There is also a method of forming a thickness step (concave shape) by evacuating with a jig at equal intervals of 200 mm in the coating direction. By this method, as shown in FIG. 2, a coating film layer 31 is formed in which a slurry is provided with vertical grooves at predetermined intervals in the longitudinal direction of the sheet-like base material to form steps.

  In FIG. 2, the shape is clearly described as a rectangular step, but it is important to have a step in the groove provided to relieve cracks when shrinking in the longitudinal direction. It only needs to contribute to the relief of rising cracks. Therefore, although the end face is rough, it can also be done by scraping off with an edge knife or the like.

  Further, as shown in FIG. 3, the coating width is adjusted to 200 mm by the doctor blade method, and the coating layer 41 continuously formed into a sheet shape is coated with polyvinyl chloride (PVC) or the like at equal intervals of 200 mm in the coating direction. A 5 mm wide tape of the anti-drying member 3 made of polyvinylidene chloride (PVDC) or the like was placed. By this method, as shown in FIG. 3, a coating layer 41 in which the drying preventing member 3 is arranged at predetermined intervals is formed on the coating layer surface in which the slurry is formed in a rectangular shape on a sheet-like base material. .

  The coating layer formation using the slurry by the doctor blade method will be described by taking as an example a coating layer in which the slurry is provided with a vertical groove at a predetermined interval in the longitudinal direction of the sheet-like substrate. FIG. 4 is an explanatory view showing a slurry forming part by a doctor blade device used for manufacturing a green sheet in which a vertical groove is provided at a predetermined interval in the longitudinal direction of a sheet-like substrate according to the present invention to form a step. is there. In the slurry molding unit 4, the thickness of the slurry 5 is controlled by the distance between the blade 6 and the substrate 2, and the substrate 2 is moved like a conveyor belt by the unwinding roll 7 and the winding roll 8, and the slurry 5 is formed into a coating layer 31 while being continuously discharged to a uniform thickness of 1 mm. The coating layer 31 moves on the base material 2 and moves up and down at a coating slurry suction device 9 composed of a jig in which a linear opening is processed on a hollow bar, and is formed at regular intervals of 200 mm. The slurry 5 applied to the substrate 2 is evacuated to form a step (concave shape) in thickness, and the slurry is perpendicular to the longitudinal direction of the sheet-like substrate at a predetermined interval as shown in FIG. The coating layer 31 is formed with a step by providing a groove.

  Next, the coating film layer which apply | coated the slurry on the base material is demonstrated. FIG. 5 is a view showing a coating layer formed on a base material formed by superposing a second member having a portion obtained by punching the slurry according to the present invention into a quadrangular shape at a predetermined interval on the first member; 5A is a perspective view, and FIG. 5B is a DD cross-sectional view. FIG. 6 is a view showing a base material formed by superposing a second member having a portion punched into a square at a predetermined interval on the first member according to the present invention. FIG. 7 is used for the production of a green sheet formed on a base material formed by superposing a second member having a portion obtained by punching the slurry according to the present invention into a square at a predetermined interval on the first member. It is explanatory drawing which shows the slurry shaping | molding part by a doctor blade apparatus.

  An example in which a sheet-like base material having a part having different peel strengths can be prepared by applying a release agent to the base material, but a sheet-like base material having parts having different peel strengths by using two members. Will be described. As shown in FIG. 5 and FIG. 6, the coating thickness of the slurry is adjusted by the doctor blade method on the base material constituted by pulling out the first member 11 and the second member 12 from the unwinding roll 7 and overlapping them. Then, the coating layer 51 is formed by continuous molding. At this time, a base material in which the peel strength of the first member 11 and the peel strength of the second member 12 are different and the peel strength of the first member 11 is higher than the peel strength of the second member 12 is used. select. As the first member, a substrate having a peel strength of 100 mN to 1000 mN / 25 mm is desirably used, and as the second member, a substrate having a peel strength of less than 100 mN / 25 mm is desirably used.

  As shown in FIG. 7, the slurry molding unit 4 that forms the coating layer on the base material formed by superposing the first member 11 and the second member 12 can obtain a desired slurry coating film thickness. There is a slurry reservoir 15 for collecting the slurry 5 to be formed on the backup roll 14 of the rotating roll, and the substrate is run and the slurry 5 is continuously discharged from the gap between the substrate and the comma roll 13. The width to be applied is adjusted by the size (width) of the slurry reservoir 15.

  The thickness of the slurry 5 is controlled by a comma roll 13 and a base material formed by superposing the second member 12 on the first member 11, and the first member 11 and the second member 12 are formed on the conveyor belt. The slurry 5 is shaped while being continuously discharged to a uniform thickness from the slurry reservoir 15, and moves on the first member 11 and the second member 12, and the coating layer 51 is formed. It is formed. Then, it is gradually dried in a drying furnace to become a green sheet.

  A drying furnace for drying the coating layer to produce a green sheet will be described. FIG. 8 is a configuration diagram of a drying furnace used for manufacturing a green sheet according to the present invention. FIG. 9 is a schematic diagram of the upper part of the drying-suppressing casing used for manufacturing the green sheet according to the present invention, and FIG. 9A is a schematic diagram in which the opening ratio of the first opening at the upper part of the casing is 20%. FIG. 9B is a schematic diagram in which the opening ratio of the first opening at the top of the housing is 60%. The aperture ratio in this case represents the ratio of the area of the first opening 24 in the upper part of the casing to the area of the upper part of the casing. The coating layer 1 on the substrate 2 passes through a drying furnace 27 and is dried to form a green sheet 21. In the upper part of the housing 22 installed in the drying furnace 27, a first opening 24 set so that the central portion of the applied coating film layer comes to the center of the first opening is arranged. The first opening 24 at the top of the housing is provided with a wire mesh as the removal speed adjusting member 23. The coating layer 1 is fed into the drying furnace 27 by a conveyor and dried while moving from the second opening 25 through which the base material of the housing 22 passes to the third opening 26 to obtain a green sheet. 21. Since the drying conditions of the drying furnace vary depending on the slurry preparation conditions and the drying furnace conditions, it is necessary to optimize appropriately.

  After such a drying step, the green sheet 21 is peeled from the base material by a peeling step for peeling the dried slurry 5 from the base material, and if necessary, cut into a desired shape and area.

  For example, the casing 22 has a first opening 24 at the upper portion of the casing set to 50% with respect to the coating width direction at the center of the coating layer, and the removal rate adjusting member 23 is # 200 mesh. Cover the first opening 24 at the top of the casing using a wire mesh with a mesh opening of 0.075 mm so that the center of the casing for the purpose of drying control coincides with the center of the coating layer 1. Install. The sieve opening represents a reference mesh interval when the wire mesh of the removal speed adjusting member 23 is defined by # (mesh: number per inch).

  The atmosphere for firing the green sheet is preferably in the air or in an atmosphere having a low oxygen concentration. As the firing furnace, an electric furnace such as a box furnace, a tubular furnace, an elevating batch furnace, or a continuous furnace can be used. Firing is performed at a temperature rising rate of 50 ° C./hour to 200 ° C./hour, a holding temperature of 900 ° C. to 1200 ° C., a holding time of 2 hours to 5 hours, and a cooling rate of 100 ° C./hour to 300 ° C./hour. Is desirable. By this step, a fired ceramic sheet can be obtained.

  In order to provide a step on the surface of the coating layer, a doctor blade for producing the coating layer will be described. FIG. 10 is a configuration diagram of a doctor blade used for manufacturing a green sheet according to the present invention. The blade 6 of the slurry molding unit 4 of the doctor blade apparatus shown in FIG. 4 is provided with uneven steps on the surface of the coating film layer as shown in FIG. By changing to the step blade 62 which is a blade, the coating layer 61 having a step in the direction orthogonal to the coating direction on the surface of the coating layer on the substrate 2 can be formed. A desired green sheet can be obtained in the drying furnace 27 by the removal speed adjusting member 23 provided on the upper portion of the housing 22 for the purpose of suppressing drying, as shown in FIG. Moreover, when providing the level | step difference of the direction orthogonal to the application direction on the surface of a coating-film layer, it is desirable that the maximum thickness of a coating-film layer is 2 times or less of the minimum thickness of a coating-film layer.

  The invention is illustrated by specific examples.

  The following examples will be described with reference to FIGS. 1 to 10 and Tables 1 to 14. In Tables 1 to 14, examples other than the preferred range in the present invention are marked with * and used as comparative examples. Further, among the evaluation items, very good ones are marked with ◎, good ones are marked with ○, and poor ones are marked with ×. In addition, as a comprehensive evaluation, when both the determination of the state of the green sheet and the state of the ceramic sheet are extremely good, ◎, when one is very good and the other is good, or when both are good, When either one was not good, it was set as x.

Example 1
The green sheet using the ceramic slurry which is the Example in this invention and the ceramic sheet obtained by baking a green sheet are demonstrated. Here, ferrite powder is used as the ceramic.

After preparing Ni—Cu—Zn-based ferrite powder having the chemical formula 27.5 (NiO _0.9 CuO _0.1 ) -23.0ZnO-49.5Fe ₂ O ₃ , acrylic acid and acrylate ester An aqueous binder solution was prepared by mixing 5 parts by weight of a water-soluble acrylic binder obtained by copolymerizing nonionic acrylate with 20 parts by weight of pure water as a volatile dispersant, and a small amount of a plasticizer and a thickener.

  Subsequently, the binder aqueous solution was added to the ferrite raw material powder having the predetermined mass, and the slurry was mixed and stirred using a mixer capable of creating a reduced-pressure atmosphere. Thus, a slurry was obtained. The slurry was applied and molded by the doctor blade method to produce a coating layer and dried.

  As shown in FIG. 4, the thickness of the slurry 5 is controlled by the distance between the blade 6 and the substrate 2, and the substrate 2 moves like a conveyor belt by two unwinding rolls 7 and a winding roll 8. The slurry 5 is molded while being continuously discharged to a uniform thickness, moves on the substrate 2, and the coating layer 31 is formed. Moreover, as shown in FIG. 8, it becomes the green sheet 21 by the peeling process which peels gradually from the drying furnace 27, and peels the dried slurry 5 from the base material 2. As shown in FIG. The drying furnace 27 is a drying furnace of about 25 m composed of a part in which the temperature is gradually raised to 40 ° C., 60 ° C., and 80 ° C. and a part to be gradually cooled, and the moving speed of the conveyor belt in the drying furnace is It was dried for about 25 minutes at 1 m / min.

  Here, a green sheet obtained by drying in a drying furnace without installing a jig for suppressing drying above the slurry 5 on the substrate 2 was used as Comparative Example 1.

  Further, in the drying furnace, a casing 22 for suppressing drying is provided above the coating film layer 1, a jig without an opening is provided on the upper portion, and a green sheet obtained by drying is compared with Comparative Example 2 and did.

  A green sheet obtained by providing a first opening 24 at the upper part of the housing in a casing for the purpose of suppressing drying and drying it was used as Sample 1. With the opening ratio of 50% with respect to the coating width direction at the center, the first opening 24 at the top of the housing is a wire mesh with a mesh opening # 200 mesh (screen opening = 0.075 mm) as the removal speed adjusting member 23. Covered.

  The green sheet 21 thus obtained was evaluated. Moreover, the ceramic sheet obtained by baking the green sheet 21 was also evaluated. The slurry film forming conditions were such that the green sheet had a width of 200 mm and a thickness of 1.0 mm. The green sheet was fired at a temperature rise rate of 100 ° C./hour and a holding temperature of 1000 ° C. in a atmospheric atmosphere using a box-type electric furnace, with a holding time of 4 hours and a temperature drop rate of 150 ° C./hour. .

  These results are shown in Table 1. The green sheet is determined by measuring the sheet thickness at the center and the outer periphery of the green sheet, and the variation rate (thickness difference / set sheet thickness × the difference between the thickness of the center and the outer periphery with respect to the set sheet thickness). 100). The criterion for determining the green sheet is “poor” when a crack has occurred, and when the crack has not occurred, the green sheet has a variation rate of 2% or less and is extremely good. If it exceeds 5% and not more than 5%, it is judged as good.

  The ceramic sheet is judged by detecting the height when the ceramic sheet is placed on the surface plate with a laser displacement meter, and warping (height of the height) with the difference between the maximum value and the minimum value with respect to the set sheet thickness. The difference between the maximum value and the minimum value / set sheet thickness × 100) was determined. Criteria for ceramic sheet are as follows: ceramic sheet warpage is very good when it is 2% or less ◎ good if it exceeds 2% and 5% or less ○ good if it exceeds 5% did. The same criteria were used in the following examples.

  As shown in Table 1, in Comparative Example 1, the variation rate of the green sheet was about 24%, and many cracks after drying occurred. The open surface side and the outer peripheral part were inevitably easy to dry, and the outer peripheral part was fixed on the substrate and started shrinking in the movement of the slurry during drying shrinkage of the coating layer. At this point, since the central portion of the slurry applied on the substrate remains undried and fluid, the slurry in the central portion of the coating layer tends to move so as to be dragged to the outer peripheral portion. As a result, cracks occurred at the center of the dried green sheet. Moreover, the defective rate in the comprehensive evaluation was about 8%.

  In Comparative Example 2, the variation rate of the green sheet was about 12%, and irregular cracks occurred in the width direction of the green sheet after drying. As a cause of cracks, the coating film layer central portion is preferentially dried by enclosing it with a casing intended to prevent drying and providing a first opening at the top of the casing. As a result, the slurry of the outer peripheral portion tends to be attracted to the central portion of the coating layer due to the movement of the slurry during drying shrinkage of the coating layer on the substrate surface. For this reason, in the advancing direction, the same shrinkage as that of the outer peripheral portion of the coating film layer is attempted, but since it is continuously formed in a strip shape, a difference in shrinkage attraction occurs in the width direction of the coating layer, and cracks are generated. The defective rate in the comprehensive evaluation was about 5%.

  In Sample 1 according to the present invention, the variation rate of the green sheet was 5% or less, and the defective rate in the comprehensive evaluation was less than 1%.

  Further, the warpage in the ceramic sheet exceeds 5% in Comparative Examples 1 and 2, and a large warp is generated, but in Sample 1, the warpage is 1.8%, which is a significant warpage. Reduction was observed.

(Example 2)
Next, as a second example of the present invention, the opening ratio of the first opening 24 was set to 50% with respect to the coating width direction of the central part of the coating layer. Furthermore, the first opening 24 was covered with a wire mesh of mesh # 200 mesh (mesh aperture = 0.075 mm) as the removal speed adjusting member 23. When the coating layer is formed in a rectangular shape at a predetermined interval as shown in FIG. 1, when a step is formed at a predetermined interval as shown in FIG. 2, at a predetermined interval as shown in FIG. A green sheet and a ceramic sheet produced by three methods when a tape having a width of 5 mm was disposed as the anti-drying member 3 on the coating layer surface were evaluated. The film forming conditions were the same as in Example 1, with the green sheet having a width of 200 mm and a thickness of 1.0 mm. The firing conditions were the same as in Example 1.

  Here, a green sheet obtained by continuously forming the slurry on the PET film as the substrate 2 to a uniform thickness was used as Comparative Example 3.

  Further, in the die slot method, as shown in FIG. 1, the slurry discharge port is intermittently discharged from a die having a width of 200 mm in which the height of the opening of the slurry discharge port is adjusted. A green sheet obtained by coating on a base material was designated as sample 2.

  In addition, by the doctor blade method, as shown in FIG. 2, after adjusting the coating width to 200 mm and continuously forming, as shown in FIG. 4, the slurry applied to the base material is sucked at equal intervals and molded. A green sheet having a step (concave shape) in thickness and forming a 200 mm square was used as Sample 3.

  In addition, as shown in FIG. 3, the doctor blade method is used to adjust the coating width to 200 mm and continuously form, and then apply polyvinyl chloride (PVC) or polyvinylidene chloride (PVDC) tape to the substrate at regular intervals. Samples 4 and 5 were green sheets that were arranged to form a 200 mm square.

  These results are shown in Table 2. The evaluation criteria for the green sheet and the ceramic sheet were the same as in Example 1.

  As shown in Table 2, in Comparative Example 3, although the variation rate of the green sheet was 5% or less, irregular cracks occurred in the center of the green sheet after drying. As a cause of cracks, the coated film layer center part is preferentially dried by surrounding it with a casing intended to prevent drying and providing an opening at the top of the casing. As a result, the substrate surface In the movement of the slurry during drying shrinkage of the coating layer above, the slurry in the outer peripheral portion tends to be attracted to the central portion of the applied coating layer. For this reason, in the advancing direction, the same shrinkage as that of the outer peripheral portion is attempted, but since it is continuously formed in a band shape, a difference in shrinkage attraction occurs in the width direction, and it is assumed that cracks have occurred. Moreover, the defective rate in comprehensive evaluation was less than 3%.

  In any of Samples 2, 3, 4, and 5 according to the present invention, the variation rate of the green sheet is 5% or less, and the green sheet is not cracked after drying. The warpage in the ceramic sheet was 1.5% or less in Samples 2, 3, 4, and 5, and a significant reduction in warpage was observed. Moreover, the defective rate in comprehensive evaluation was less than 1%.

  For sample 3, the coating width was adjusted to 200 mm by the doctor blade method, and after continuous molding, the slurry applied to the substrate was sucked at equal intervals to form a step (concave shape) in the molding thickness to 200 mm. It is a green sheet that becomes a square. In this example, no cracks occurred, but even if cracks occur, the slurry on the outer periphery tends to be uniformly attracted to the central part of the square coating layer, and there is a difference in thickness due to the stepped part. It occurs at a certain point and does not crack at the center of the green sheet.

  For samples 4 and 5, the coating width was adjusted to 200 mm by the doctor blade method, and after continuous molding, polyvinyl chloride (PVC) or polyvinylidene chloride (PVDC) tape was placed on the coating layer surface at regular intervals. Thus, by using a green sheet having a square shape of 200 mm, drying is prevented, and a step (concave shape) is formed in the molded body due to the difference in the degree of drying from the portion where the tape is not disposed. In this example, both did not crack, but even if cracked, the slurry of the outer periphery tends to be uniformly attracted to the center of the coating layer applied to the square, drying is It occurs in the tape placement portion of the drying prevention member that is slowed down, so that cracks do not occur in the center of the green sheet.

(Example 3)
Next, as a third example of the present invention, the opening ratio of the first opening at the top of the housing was set to 50% with respect to the coating width direction at the center of the coating layer. Further, the first opening was covered with a mesh # 200 mesh (mesh opening = 0.075 mm) of the removal speed adjusting member. The green sheet and the ceramic sheet obtained by firing the green sheet when the slurry molding thickness was changed were evaluated. The film forming conditions are the same as in Sample 3 of Example 2, the green sheet width is 200 mm, the slurry forming thickness is changed, and after continuous forming, the slurry applied to the substrate is sucked at equal intervals. Then, a step (concave shape) was formed to form a 200 mm square green sheet. The firing conditions were the same as in Example 1.

  The evaluation result performed by changing the slurry molding thickness to 0.15 mm, 0.30 mm, 1.00 mm, 1.50 mm, and 1.60 mm is shown.

  As shown in Table 3, in Comparative Example 4, the variation rate of the green sheet was 5% or more. By enclosing with a casing intended to prevent drying of the present invention and providing an opening at the top of the casing, the volatile dispersion medium evaporated from the slurry will remain around the slurry, but because the slurry molding thickness is thin It is thought that the concentration of the volatile dispersion medium was low and the drying was promoted. As a result, the film has been dried before being uniformly shrunk, so that it is assumed that an irregular thickness difference occurs. Moreover, the defective rate in comprehensive evaluation was about 4%.

  In Comparative Example 5, the variation rate of the green sheet is as large as 5% or more. Since the slurry molding thickness is thick, the volatile dispersion medium evaporated from the slurry stays around the slurry in the casing. Therefore, it is considered that the concentration of the volatile dispersion medium has become too high and drying has been suppressed. As a result, drying in the casing installed in the furnace became insufficient, and it was dried by hot air in the latter half of the drying furnace, which caused a difference in shrinkage between the central part and the outer peripheral part, and it was estimated that the difference in thickness became large Is done. Moreover, the defective rate in comprehensive evaluation was less than 3%.

  When the slurry molding thickness of Samples 4 to 6 according to the present invention was 0.3 mm or more and 1.5 mm or less, the variation rate of the green sheet was 2% or less.

  Further, the ceramic sheet obtained by firing the green sheet was evaluated, and as shown in Table 3, a good result with a warpage of 3% or less in a slurry molding thickness range of 0.3 mm to 1.5 mm was obtained. Obtained. A large reduction in warpage was observed. In addition, the defect rate in the overall evaluation was less than 1%.

Example 4
Next, as a fourth example of the present invention, the opening ratio of the first opening at the top of the housing was set to 50% with respect to the coating width direction at the center of the coating layer. Further, the first opening was covered with a mesh # 200 mesh (mesh opening = 0.075 mm) of the removal speed adjusting member. The green sheet and the ceramic sheet obtained by firing the green sheet when the slurry molding thickness was changed were evaluated. The film forming conditions were the same as those of Samples 4 and 5 of Example 2, the width of the green sheet was 200 mm, the slurry forming thickness was changed, and after continuous forming, the film was formed at an equal interval of 5 mm on the coating layer surface. A width polyvinylidene chloride (PVDC) tape was placed into a 200 mm square. The firing conditions were the same as in Example 1.

  Evaluation results obtained by changing the slurry molding thickness to 0.20 mm, 0.30 mm, 1.00 mm, 1.50 mm, and 1.60 mm are shown.

  As shown in Table 4, in Comparative Example 6, the variation rate of the green sheet was 5% or more. By enclosing with a casing for the purpose of inhibiting drying of the present invention and providing a first opening at the top of the casing, the volatile dispersion medium evaporated from the coating film layer will remain around the coating film layer, Since the slurry molding thickness is thin, the concentration of the volatile dispersion medium is low, which is thought to promote drying. As a result, the film has been dried before being uniformly shrunk, so that it is assumed that an irregular thickness difference occurs. Moreover, the defective rate in comprehensive evaluation was about 4%.

  In Comparative Example 7, the variation rate of the green sheet is as large as 8% or more. Since the molding thickness is thick, the volatile dispersion medium evaporated from the coating film layer in the casing stays around the coating film layer. Therefore, it is considered that the concentration of the volatile dispersion medium has become too high and drying has been suppressed. As a result, drying in the casing installed in the furnace became insufficient, and it was dried by hot air in the latter half of the drying furnace, which caused a difference in shrinkage between the central part and the outer peripheral part, and it was estimated that the difference in thickness became large Is done. Moreover, the defective rate in comprehensive evaluation was less than 4%.

  When the slurry molding thickness of samples 9 to 11 according to the present invention was 0.3 mm or more and 1.5 mm or less, the variation rate of the green sheet was 2% or less.

  Further, the ceramic sheet obtained by firing the green sheet was evaluated, and as shown in Table 4, a good result with a warp of 2% or less in a slurry molding thickness range of 0.3 mm to 1.5 mm was obtained. Obtained. A large reduction in warpage was observed. In addition, the defect rate in the overall evaluation was less than 1%.

(Example 5)
Next, as a fifth embodiment of the present invention, the green sheet and the green sheet obtained by changing the shape of the removal speed adjusting member provided in the first opening at the top of the housing were obtained. The ceramic sheet was evaluated. The slurry film formation conditions are the same as in Example 1, the green sheet width is 200 mm, the thickness is 1.0 mm, the coating width is adjusted to 200 mm by the doctor blade method, and after continuous molding, etc. The slurry applied to the substrate at intervals was sucked to form a step (concave shape) to obtain a green sheet having a 200 mm square. The firing conditions were the same as in Example 1.

  As shown in FIG. 8, the opening condition of the wire mesh of the removal speed adjusting member 23 covering the first opening 24 provided in the upper part of the housing 22 for the purpose of suppressing drying in the drying furnace 27 is expressed by # Evaluation results obtained by changing to 250 mesh, # 200 mesh, # 10 mesh, and # 9 mesh are shown.

  As shown in Table 5, in Comparative Example 8, the variation rate of the green sheet was good at 5% or less, but cracks occurred in the outer peripheral portion. Surrounding with a casing intended to prevent drying of the coating layer on the substrate, and providing a first opening at the top of the casing, it is possible to prevent sticking to the substrate due to drying of the outer periphery of the coating slurry. Although it can be ensured, the removal speed adjusting member has a small mesh shape, so that the outer periphery of the coating slurry cannot be prevented from adhering to the base material, and the slurry at the center of the coating layer is the outer periphery. It is presumed that cracks occurred in the outer peripheral portion of the coating layer when attracted to the shrinkage of the coating layer.

  In Comparative Example 9 as well, the variation rate of the green sheet was good at 4% or less, but cracks occurred at the center. Due to the large opening shape of the removal rate adjusting member, drying of the coating layer center is accelerated, and when the slurry on the outer periphery is dried and attracted, it is assumed that cracks occurred in the coating layer center. The

  In both Samples 12 and 13 according to the present invention, the variation rate of the green sheet was 3% or less, and the defect rate in the comprehensive evaluation was also less than 1%. Moreover, the green sheet does not crack after drying. Regarding the warpage in the ceramic sheet, in Comparative Examples 8 and 9, the warpage was good at less than 5%, but in Samples 12 and 13, the warpage was 2% or less, and a significant reduction in warpage was observed. . In addition, the defective rate in the overall evaluation was less than 1%.

(Example 6)
Next, as a sixth embodiment of the present invention, the green sheet and the green sheet obtained by changing the shape of the removal speed adjusting member provided in the first opening at the top of the casing were obtained. The ceramic sheet was evaluated. The slurry film forming conditions were the same as Samples 4 and 5 of Example 2, the green sheet had a width of 200 mm and a thickness of 1.0 mm, and the coating width was adjusted to 200 mm by the doctor blade method and continuously formed. Thereafter, polyvinylidene chloride (PVDC) tape having a width of 5 mm on the coating layer surface was arranged at equal intervals of 200 mm. The firing conditions were the same as in Example 1.

  As shown in FIG. 8, the opening condition of the wire mesh of the removal speed adjusting member 23 covering the first opening 24 provided in the upper part of the housing 22 for the purpose of suppressing drying in the drying furnace 27 is expressed by # Evaluation results obtained by changing to 250 mesh, # 200 mesh, # 10 mesh, and # 9 mesh are shown.

  As shown in Table 6, in Comparative Example 10, the variation rate of the green sheet was 5% or more, and cracks occurred on the outer peripheral portion. Surrounding with a casing intended to prevent drying of the coating layer on the substrate, and providing a first opening at the top of the casing, it is possible to prevent sticking to the substrate due to drying of the outer periphery of the coating slurry. Although it can be ensured, the removal speed adjusting member has a small mesh shape, so that the outer periphery of the coating slurry cannot be prevented from adhering to the base material, and the slurry at the center of the coating layer is the outer periphery. It is presumed that cracks occurred in the outer peripheral portion of the coating layer when attracted to the shrinkage of the coating layer.

  Also in Comparative Example 11, cracks occurred in the central portion when the variation rate of the green sheet was 7% or more. Due to the large opening shape of the removal rate adjusting member, drying of the coating layer center is accelerated, and when the slurry on the outer periphery is dried and attracted, it is assumed that cracks occurred in the coating layer center. The

  In both samples 14 and 15 according to the present invention, the variation rate of the green sheet was 2% or less. Moreover, the crack of the green sheet after drying does not generate | occur | produce. Regarding the warpage in the ceramic sheet, in Comparative Examples 10 and 11, the warpage was good at 5% or less, but cracking occurred as described above. On the other hand, in Samples 14 and 15, the warpage was very good at 1% or less, and a remarkable reduction in warpage was observed. In addition, the defective rate in the overall evaluation was less than 1%.

(Example 7)
Next, as a seventh embodiment of the present invention, the first opening in the upper part of the casing is green above the base material and the applied slurry in the central part with respect to the coating width direction. Sheets and ceramic sheets were evaluated. The first opening was covered with a mesh # 200 mesh (mesh opening = 0.075 mm) which is a removal speed adjusting member. The film forming conditions were the same as in Sample 3 of Example 2, the ceramic sheet having a width of 200 mm and a thickness of 1.0 mm, and the coating width was adjusted to 200 mm by the doctor blade method and was continuously formed. Thereafter, the slurry applied to the substrate at regular intervals was sucked to form a step (concave shape) to obtain a green sheet having a 200 mm square. The firing conditions were the same as in Example 1.

  Evaluation results obtained by changing the opening ratio of the first opening at the top of the housing to 10%, 20%, 50%, and 60% are shown.

  As shown in Table 7, in Comparative Example 12, the variation rate of the green sheet is small and good at about 3%, but the warpage of the ceramic sheet after firing is as large as 6%. It is considered that the volatile dispersion medium evaporated from the slurry stays around the slurry in the casing, and the concentration of the volatile dispersion medium becomes too high, and the drying is suppressed too much. Also, in the casing installed in the furnace, the drying was insufficient, and drying was performed by hot air in the latter half of the drying furnace, so that the drying proceeded preferentially from the open surface opposite to the base material, and the base material side and the open surface It is thought that there was a difference in the degree of densification of the ceramic raw material powder in the green sheet on the side. Thus, when the degree of densification of the ceramic raw material powder in the green sheet differs depending on the location in the green sheet, the ceramic sheet after firing is likely to warp.

  In Comparative Example 13, the variation rate of the green sheet was good at 5% or less, but cracks occurred at the center. Because the shape of the first opening (opening ratio) is large, drying at the center of the coating layer accelerates, and when the slurry on the outer periphery is dried and attracted, cracks occur at the center of the coating layer. It is guessed.

  In both the samples 16 and 17 according to the present invention, the variation rate of the green sheet is 2% or less, and the green sheet is not cracked after drying. Moreover, about the curvature in the fired ceramic sheet, in samples 16 and 17, the curvature was 2% or less, and a remarkable reduction of the curvature was observed. In addition, the defective rate in the overall evaluation was less than 1%.

(Example 8)
Next, as an eighth embodiment of the present invention, the green when the first opening at the top of the housing is changed to the upper part of the base material and the central part of the applied slurry with respect to the coating width direction. Sheets and ceramic sheets were evaluated. The first opening was covered with a mesh # 200 mesh (mesh opening = 0.075 mm) which is a removal speed adjusting member. The film forming conditions were the same as Sample 5 of Example 2, the width of the ceramic sheet was 200 mm, the thickness was 1.0 mm, the coating width was adjusted to 200 mm by the doctor blade method, and after continuous molding, Polyvinylidene chloride (PVDC) tape having a width of 5 mm on the coating layer surface was arranged at equal intervals to form a 200 mm square. The firing conditions were the same as in Example 1.

  Evaluation results obtained by changing the opening ratio of the first opening at the top of the housing to 10%, 20%, 50%, and 60% are shown.

  As shown in Table 8, in Comparative Example 14, the variation rate of the green sheet is small and good at about 3%, but the warpage of the ceramic sheet after firing is as large as 6%. It is considered that the volatile dispersion medium evaporated from the slurry stays around the slurry in the casing, and the concentration of the volatile dispersion medium becomes too high, and the drying is suppressed too much. In addition, in the casing installed in the furnace, the drying was insufficient, and drying was performed by hot air in the latter half of the drying furnace, so that the drying proceeded preferentially from the open surface on the side opposite to the base material, and the base material side and the open surface It is thought that there was a difference in the degree of densification of the ceramic raw material powder in the green sheet on the side. Thus, when the degree of densification of the ceramic raw material powder in the green sheet differs depending on the location in the green sheet, the ceramic sheet after firing is likely to warp.

  In Comparative Example 15, the variation rate of the green sheet was as large as about 7%, and cracks occurred at the center. Because the shape of the first opening (opening ratio) is large, drying at the center of the coating layer accelerates, and when the slurry on the outer periphery is dried and attracted, cracks occur at the center of the coating layer. It is guessed.

  In both samples 18 and 19 according to the present invention, the variation rate of the green sheet is about 1% or less, and the green sheet does not crack after drying. Moreover, about the curvature in the fired ceramic sheet, in the samples 18 and 19, the curvature was 2% or less, and the remarkable reduction of the curvature was seen. In addition, the defect rate in the overall evaluation was 1% or less.

Example 9
Next, as a ninth embodiment of the present invention, as shown in FIG. 7, the slurry 5 has a square or rectangular coating area of 400 cm ² or less on the first member 11 having peel strength with the comma roll 13. Then, a base material constituted by superposing the second members 12 having peel strengths that were pulled out into a quadrangular shape at equal intervals was used. As the first member, Toyobo Ester Film off-line processed product E 7002 (manufactured by Toyobo) having a peel strength of 100 mN to 1000 mN / 25 mm, and as the second member, Toyobo Ester Film E5007 having a peel strength of less than 100 mN / 25 mm Made by Toyobo Co., Ltd.). In the following examples, the above substrate was used. The thickness is controlled by the distance from the base material, and the base material composed of the first member 11 and the second member 12 moves like a conveyor belt, and the slurry 5 continues to a uniform thickness. Then, the film is formed while being discharged and moves on the base material constituted by the first member 11 and the second member 12, and the coating layer 51 is formed. Further, as shown in FIG. 8, the green slurry is gradually dried in the drying furnace 27, and the dried slurry 5 is peeled off from the base material constituted by the first member 11 and the second member 12. Sheet 21 is obtained. The drying furnace 27 is a drying furnace of about 25 m composed of a part in which the temperature is gradually raised to 40 ° C., 60 ° C., and 80 ° C. and a part that is gradually cooled, and the substrate traveling speed in the drying furnace is 1 m. / Min. For about 25 minutes.

  Here, a green sheet obtained by drying in a drying furnace without installing a jig for suppressing drying above the slurry 5 on the substrate 2 was used as Comparative Example 16.

  Further, in the drying furnace, a green sheet obtained by drying by providing a casing 22 for suppressing drying above the coating film layer 51 and installing a jig having no opening in the upper part is obtained as Comparative Example 17. It was.

  A green sheet obtained by providing the first opening 24 at the top of the housing in the casing for the purpose of drying control and drying it was used as a sample 20. With the opening ratio of 50% with respect to the coating width direction at the center, the first opening 24 at the top of the housing is a wire mesh with a mesh opening # 200 mesh (screen opening = 0.075 mm) as the removal speed adjusting member 23. Covered.

  The green sheet 21 thus obtained was evaluated. Moreover, the ceramic sheet obtained by baking the green sheet 21 was also evaluated. The slurry film forming conditions were such that the green sheet had a width of 200 mm and a thickness of 0.8 mm. The green sheet was fired using a box-type electric furnace in an air atmosphere at a temperature rising rate of 100 ° C./hour and a holding temperature of 1000 ° C., with a holding time of 4 hours and a cooling rate of 150 ° C./hour.

  The result obtained by changing the drying conditions of the green sheet is shown.

  As shown in Table 9, in Comparative Example 16, the variation rate of the green sheet was about 10%, and many cracks after drying occurred. The open surface side and the outer peripheral part were inevitably easy to dry, and the outer peripheral part was fixed on the substrate and started shrinking in the movement of the slurry during drying shrinkage of the coating layer. Since the central part of the slurry applied on the substrate is in an undried and fluid state, the slurry in the central part of the coating layer tends to move so as to be dragged from the outer peripheral part. Cracks occurred at the center of the green sheet after drying. Moreover, the defective rate in comprehensive evaluation was about 10%.

  In Comparative Example 17, the variation rate of the green sheet was about 8%, and irregular cracks occurred in the width direction of the green sheet after drying. As a cause of cracks, the coating film layer was preferentially dried at the center by enclosing it in a casing intended to prevent drying and providing a first opening at the top of the casing. As a result, the movement of the slurry during drying shrinkage of the coating layer on the substrate surface tends to attract the slurry of the outer peripheral portion to the central portion of the coating layer, and the same drying as the outer peripheral portion of the coating layer in the traveling direction Although it tried to shrink, since it was continuously formed in a strip shape, a difference in shrinkage attraction occurred in the width direction of the coating layer, and cracks occurred. Moreover, the defective rate in comprehensive evaluation was about 5%.

  In the sample 20 according to the present invention, the variation rate of the green sheet was about 5% or less, and the defect rate in the comprehensive evaluation was less than 1%.

  Further, the warpage in the ceramic sheet exceeds 5% in Comparative Examples 16 and 17, and a large warp is generated, but in the sample 20, the warpage is 1.8%, which is a significant warpage. Reduction was observed.

(Example 10)
Next, as a tenth embodiment of the present invention, in FIG. 8, the opening ratio of the first opening portion is set to the first opening portion 24 at the upper portion of the casing with respect to the coating width direction of the coating layer center portion. The first opening was covered with a wire mesh having a mesh opening size of # 200 mesh (mesh opening = 0.075 mm) as the removal speed adjusting member 23. The base material on which the coating layer is applied is a base material formed by superposing the second member 12 punched into a quadrangle having a square application area of 400 cm ² or less at equal intervals on the first member 11. The green sheet obtained by applying the slurry and the ceramic sheet obtained by firing it were evaluated. The film forming conditions were such that the green sheet had a width of 200 mm and a thickness of 1.0 mm. The firing conditions were the same as in Example 9.

  Here, a green sheet obtained by forming the coating layer 51 on the first member and drying it in a drying furnace was used as Comparative Example 18.

  Further, a green sheet obtained by forming the coating layer 51 on the second member and drying it in a drying furnace was defined as Comparative Example 19.

  These results are shown in Table 10. The evaluation criteria for the green sheet and the ceramic sheet were the same as in Example 1.

  As shown in Table 10, in Comparative Example 18, the variation rate of the green sheet was 5% or less, and cracks after drying occurred irregularly. When the coating layer is formed on the first member, it is surrounded by a casing intended to prevent drying, and the central part of the applied slurry is preferentially dried by providing an opening at the top of the casing. Thus, in the movement of the slurry during the drying shrinkage of the slurry on the substrate surface, the outer peripheral slurry tends to be attracted to the central portion of the applied slurry. However, the coating layer tends to retain its shape in the thickness direction, but tends to repel the slurry on a substrate having a low peel strength, and the shape cannot be maintained. End up. This tendency occurs modestly as the thickness increases, the thickness of the outer periphery varies, and the attracting force during drying shrinkage is not uniform. Will occur. Moreover, the defective rate in comprehensive evaluation was about 5%.

  Further, in Comparative Example 19, when the coating layer was formed on the first member, it was surrounded by a casing intended to prevent drying, and the center of the slurry applied by providing an opening at the top of the casing The part is preferentially dried, and the slurry of the outer peripheral part tends to be attracted to the central part of the applied slurry in the movement of the slurry during the drying shrinkage of the slurry on the substrate surface. However, the coating layer tends to dry shrink at the central portion of the coating layer, but cannot move because of low peel strength, and is fixed on the substrate. Therefore, a crack will occur in a portion that is undried and remains fluid in the drying process. Moreover, the defective rate in comprehensive evaluation was about 12%.

  In the sample 21 according to the present invention, the variation rate of the green sheet was about 3%, and there was no generation of cracks after drying. Moreover, about the curvature in the fired ceramic sheet | seat, it is 2% or less, and the reduction | decrease of remarkable curvature was seen. In addition, the defective rate in the overall evaluation was 1% or less.

  A base formed by superimposing a second member 12 having a coating width adjusted to 200 mm by a doctor blade method and having a coating layer punched into a 200 mm square on the first member 11 at equal intervals. In the green sheet obtained by coating on the material, it is surrounded by a casing intended to prevent drying, and the central part of the applied slurry is preferentially dried by providing an opening at the top of the casing. become. In the movement of the slurry during the drying shrinkage of the slurry on the substrate surface, the slurry in the outer peripheral portion tends to be attracted to the central portion of the applied slurry. The coating layer of the member having low peel strength can be freely dried and shrunk, but the coating layer of the member having high peeling strength is fixed on the substrate. In this example, cracks did not occur, but even if cracks occur, a difference in stress occurs at the boundary between the member having high peel strength and the member having low peel strength, and cracks are likely to occur. The center of the green sheet is not cracked.

(Example 11)
Next, as an eleventh embodiment of the present invention, the green sheet in the case where the first opening at the top of the housing is changed to the upper part of the base material and the center of the applied slurry in the coating width direction. And ceramic sheets were evaluated. The first opening was covered with a wire mesh of # 200 mesh (screen opening = 0.075 mm) of the removal speed adjusting member. As shown in FIG. 6 and FIG. 7, the coating layer is formed on the base material in which the second member 12 having a portion punched into a square of 200 mm at equal intervals on the first member 11 is superimposed. 51 was formed, and the film forming conditions were that the green sheet had a width of 200 mm and a thickness of 1.0 mm. The firing conditions were the same as in Example 9.

  The evaluation performed by changing the opening ratio of the first opening in the upper part of the housing to 10%, 20%, 50%, and 60% as shown in FIG.

  As shown in Table 11, in Comparative Example 20, the variation rate of the green sheet is small and good at about 3%, but the warpage of the ceramic sheet after firing is as large as 6%. In the housing, the volatile dispersion medium evaporated from the slurry remains around the slurry, and the concentration of the volatile dispersion medium becomes too high. In addition, because drying in the case installed in the furnace was insufficient and was dried by hot air in the latter half of the drying furnace, drying proceeded preferentially from the open surface opposite to the base material, and the base material side and open surface It is thought that there was a difference in the degree of densification of the ceramic raw material powder in the green sheet on the side. Thus, when the degree of densification of the ceramic raw material powder in the green sheet differs depending on the location in the green sheet, the ceramic sheet after firing is likely to warp.

  In Comparative Example 21, the variation rate of the green sheet was about 7%, and cracks occurred at the center. Because the shape of the first opening (opening ratio) is large, drying at the center of the coating layer accelerates, and when the slurry on the outer periphery is dried and attracted, cracks occur at the center of the coating layer. It is guessed.

  In both the samples 22 and 23 according to the present invention, the variation rate of the green sheet is about 1%, and the green sheet does not crack after drying. Regarding the warpage in the fired ceramic sheet, in Samples 22 and 23, the warpage was 2% or less, and a significant reduction in warpage was observed. In addition, the defect rate in the overall evaluation was 1% or less.

(Example 12)
Next, as a twelfth embodiment of the present invention, a green sheet and a ceramic sheet were evaluated when the shape of the removal speed adjusting member provided in the first opening at the top of the housing was changed. The film forming conditions are such that the green sheet has a width of 200 mm and a thickness of 1.0 mm, and a second member 12 having a portion punched into a 200 mm square at equal intervals is superimposed on the first member 11. A coating layer was formed on the combined substrate. The firing conditions were the same as in Example 9.

  As shown in FIG. 8, the opening condition of the wire mesh of the removal speed adjusting member covering the first opening 24 provided in the upper part of the housing 22 for the purpose of suppressing drying in the drying furnace 27 is set to # 250 mesh. , # 200 mesh, # 10 mesh, and # 9 mesh are shown and the evaluation results are shown.

  As shown in Table 12, in Comparative Example 22, the variation rate of the green sheet was 5% or more, and the outer peripheral portion was cracked. Enclosed in a case for the purpose of suppressing drying of the coating layer on the base material, and by providing a first opening at the top of the case, it is more reliable to prevent the coating slurry from sticking to the base material due to drying of the outer periphery. Can be. However, because the opening shape of the removal rate adjusting member of the first opening is small, it is not possible to prevent the coating slurry from adhering to the base material by drying the outer periphery, and the slurry at the center of the coating layer is the outer periphery. It is presumed that cracks occurred in the outer periphery of the coating slurry when attracted by the shrinkage of the coating slurry.

  In Comparative Example 23, the variation rate of the green sheet was 7% or more, and cracks occurred in the center. Due to the large opening shape of the removal rate adjusting member of the first opening, the drying of the coating layer center is accelerated, and when the slurry on the outer periphery is dried and attracted, cracks are generated in the coating layer center. Presumed to have occurred.

  In both the samples 24 and 25 according to the present invention, the variation rate of the green sheet was 2% or less. Moreover, the crack of the green sheet after drying does not generate | occur | produce. The warpage in the ceramic sheet is good at 5% or less in Comparative Examples 22 and 23, but the warpage is 1% or less in Samples 24 and 25, and a significant reduction in warpage is observed. In addition, the defect rate in the overall evaluation was 1% or less.

(Example 13)
Next, as a thirteenth embodiment of the present invention, the opening ratio of the first opening portion was set to 50% with respect to the coating width direction of the central portion of the coating layer. Further, the first opening was covered with a wire mesh of # 200 mesh (screen opening = 0.075 mm) of the removal speed adjusting member. The green sheet and the ceramic sheet when the slurry molding thickness was changed were evaluated. The base material was apply | coated on the base material which overlapped and comprised the 2nd member which has the part pierced into the square of 200 mm at equal intervals on the 1st member. The film forming conditions were such that the green sheet had a width of 200 mm and a thickness of 1.0 mm. The firing conditions were the same as in Example 9.

  Evaluation results obtained by changing the slurry molding thickness to 0.15 mm, 0.30 mm, 1.00 mm, 1.50 mm, and 1.60 mm are shown.

  As shown in Table 13, in Comparative Example 24, the variation rate of the green sheet was 6% or more. Surrounded by a case for the purpose of inhibiting drying according to the present invention, an opening is provided at the top of the case, and the volatile dispersion medium evaporated from the slurry will remain around the slurry. It is thought that the concentration of the dispersion medium was low and drying was promoted. As a result, the film has been dried before being uniformly shrunk, so that it is assumed that an irregular thickness difference occurs. Moreover, the defective rate in comprehensive evaluation was about 4%.

  In Comparative Example 25, the variation rate of the green sheet was 5% or more, and cracks occurred at the center. Since the molding thickness is large, it is considered that the volatile dispersion medium evaporated from the slurry stayed around the slurry in the casing, and the concentration of the volatile dispersion medium became too high, thereby suppressing the drying. As a result, drying in the casing installed in the furnace became insufficient, and it was dried by hot air in the latter half of the drying furnace, which caused a difference in shrinkage between the central part and the outer peripheral part, and it was estimated that the difference in thickness became large Is done. Moreover, the defective rate in comprehensive evaluation was about 3%.

  When the molding thickness of sample 26 to sample 28 according to the present invention was 0.3 mm or more and 1.5 mm or less, the variation rate was 2% or less in the evaluation, and the stability was good. In addition, the defect rate in the overall evaluation was less than 1%.

  Further, the ceramic sheet obtained by firing the green sheet was evaluated, and as shown in Table 13, good results with a warpage of 2% or less in a slurry forming thickness range of 0.3 mm to 1.5 mm. Got. In addition, a significant reduction in warpage was observed.

  In Examples 9 and 10, the peel strength of the first member 11 is set to 100 mN to 1000 mN / 25 mm, and the peel strength of the second member 12 is set to less than 100 mN / 25 mm. Means are not concerned. For example, when a release material is used, either a silicone type used for general adhesive products or a non-silicone type mainly used in electronic device applications where silicone is likely to have an adverse effect may be used. Moreover, although the difference is provided in peeling strength by two members, it is good also as a structure in which peeling strength differs by apply | coating the peeling agent etc. which change peeling strength to a base material at a predetermined space | interval.

(Example 14)
Next, as a fourteenth example of the present invention, the opening ratio of the first opening portion was set to 50% with respect to the coating width direction of the central portion of the coating layer. Further, the first opening was covered with a wire mesh of # 200 mesh (screen opening = 0.075 mm) of the removal speed adjusting member. The width direction of the green sheet when the thickness of the coating film layer is changed by providing a step in the direction perpendicular to the coating direction on the surface of the coating film layer in the housing provided with an opening for the purpose of suppressing drying The thickness of was evaluated. Moreover, the ceramic sheet obtained by baking a green sheet was also evaluated.

  The width of the coating layer was adjusted to 200 mm by the doctor blade method. As shown in Fig. 10, the blade is unevenly formed so that a step in the direction perpendicular to the coating direction can be formed on the surface of the desired coating layer, and the coating slurry with the coating layer thickness adjusted is continuously formed. did. Thereafter, the slurry applied to the substrate was sucked at equal intervals of 200 mm in the application direction, and applied to a square by forming a step (concave shape) in the molding thickness. The firing conditions were the same as in Example 9.

  The molding thickness of the slurry is such that the central portion is 0.50 mm and the outer peripheral portion is 0.60 mm, 0.00 mm so that the maximum thickness with a step on the surface of the coating layer is not more than twice the minimum thickness. The evaluation results for Samples 29, 30, 31, and 32 when 80 mm and 1.00 mm and when the central portion is 1.00 mm and the outer peripheral portion is 0.50 mm are shown. Further, as Comparative Example 26, the central part was 0.50 mm and the outer peripheral part was 1.10 mm so that the maximum thickness provided with a step on the surface of the coating layer was larger than twice the minimum thickness. The evaluation result performed about the case is shown.

  As shown in Table 14, in Comparative Example 26, a crack occurred at the boundary of the step in the direction perpendicular to the coating direction in which the thickness changed on the surface of the coating layer of the green sheet. The volatile dispersion medium evaporated from the slurry remains in the periphery of the slurry by being surrounded by the casing for the purpose of suppressing drying according to the present invention and providing an opening at the top of the casing. However, if the maximum thickness with a step on the surface of the coating layer is greater than twice the minimum thickness, there will be a difference in the shrinkage between the thick and thin portions of the coating layer. The shrinkage at the end does not catch up with the central portion, resulting in uneven drying. As a result, it is presumed that a crack will occur at the boundary of the step in the direction perpendicular to the coating direction in which the thickness changes on the surface of the coating layer.

  The maximum thickness of the coating layer corresponding to the present invention of samples 29, 30, 31, and 32 is 1.2 times (thickness difference is 0.1 mm) to 2.0 times (thickness difference is 0.5 mm). Then, in evaluation, it was favorable without generation of cracks. In addition, the ceramic sheet obtained by firing the green sheet was evaluated. As shown in Table 14, the maximum thickness of the coating layer was 1.2 times the minimum thickness (thickness difference was 0.00). In the range of 1 mm) to 2.0 times (thickness difference of 0.5 mm), good results were obtained in which the warpage was reduced to 5% or less. In addition, the defective rate in the overall evaluation was 1% or less.

  In this example, two steps were provided on the surface of the coating film layer in a direction perpendicular to the direction of application of the coating film layer. With such a configuration, when the final product of the ceramic sheet product is, for example, RFID (Radio Frequency IDentification: individual identification by radio waves), a step is provided by changing the thickness of the coating layer according to the RFID antenna shape. This makes it possible to reduce the number of post-process steps.

  Further, in the above embodiment, the formation of the ferrite green sheet is a configuration using a doctor blade method, but if it is a method that can be formed in a rectangular shape, an extrusion method can be applied, There is no problem even if a die coater, a lip coater, a dip method or the like is applied instead of the doctor blade method.

  Moreover, in the said Example, it becomes the structure which arrange | positions a polyvinyl chloride (PVC) or a polyvinylidene chloride (PVDC) tape on the coating-film layer surface, and although the tape width to arrange | position is 5 mm, drying can be suppressed. As long as there is no cracking or warping, the tape width is 5 mm. In addition, materials other than polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) may be used as long as drying can be suppressed by disposing on the coating layer surface without causing thermal contraction.

  Furthermore, as firing conditions for obtaining a ceramic sheet, it is possible to control the atmosphere and appropriately select the temperature profile and firing time. That is, various changes and modifications that can be naturally made by those skilled in the art are also included in the present invention.

DESCRIPTION OF SYMBOLS 1, 31, 41, 51, 61 Coating layer 2 Base material 3 Drying prevention member 4 Slurry shaping | molding part 5 Slurry 6 Blade 7 Unwinding roll 8 Take-up roll 9 Application | coating slurry suction apparatus 11 First member 12 Second member 13 Comma roll 14 Backup roll 15 Slurry pool 21 (Ceramic) green sheet 22 Case 23 Removal speed adjusting member 24 First opening 25 Second opening 26 Third opening 27 Drying furnace 62 Step blade

Claims (20)

  A slurry forming step of forming a flat coating layer by applying a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed onto a sheet-like substrate, and a drying furnace after the slurry forming step A method for producing a ceramic green sheet, comprising: a drying step of evaporating and removing the volatile dispersion medium of the slurry; and a peeling step of peeling the slurry from a substrate after the drying step, In the step, the coating layer is provided with a region where the thickness is reduced at a predetermined interval, and in the drying step, means for adjusting the removal rate of the volatile dispersion medium in the drying furnace is provided. A method for producing a ceramic green sheet.   A slurry forming step of forming a flat coating layer by applying a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed onto a sheet-like substrate, and a drying furnace after the slurry forming step A method for producing a ceramic green sheet, comprising: a drying step of evaporating and removing the volatile dispersion medium of the slurry; and a peeling step of peeling the slurry from a substrate after the drying step, In the process, a drying prevention member is disposed at a predetermined interval on the coating layer surface, and in the drying process, means for adjusting the removal rate of the volatile dispersion medium in the drying furnace is provided. A method for producing a ceramic green sheet.   A slurry molding step of forming a flat coating layer by applying a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed onto a sheet-like base material having portions having different peel strengths, A drying step of evaporating and removing the volatile dispersion medium in the drying furnace in a drying furnace after the slurry forming step and removing the slurry from the substrate after the drying step A method for producing a ceramic green sheet comprising a step.   The base material is composed of two members, and is configured by superposing a sheet-like second member having a portion punched into a rectangle at a predetermined interval on a sheet-like first member. The method for producing a ceramic green sheet according to claim 3.   The method for producing a ceramic green sheet according to claim 4, wherein the peel strength of the first member is higher than the peel strength of the second member.   The means for adjusting the removal speed includes a first opening through which the volatile dispersion medium evaporated on at least one surface passes, and second and third through which the substrate on which the coating layer is formed passes. The ceramic green according to any one of claims 1 to 5, wherein the ceramic green comprises a housing having an opening, and a removal speed adjusting member is attached to the first opening having a predetermined opening ratio. Sheet manufacturing method.   The method for producing a ceramic green sheet according to claim 6, wherein the first opening has an opening ratio of 20% to 50%.   8. The removal speed adjusting member is a wire mesh having a mesh size of # 200 mesh (mesh opening = 0.075 mm) or less and 10 mesh (mesh opening = 1.70 mm) or more. Manufacturing method of ceramic green sheet.   9. The method for producing a ceramic green sheet according to claim 1, wherein in the slurry forming step, the maximum thickness of the slurry forming thickness is 0.3 mm or more and 1.5 mm or less.   The method for producing a ceramic green sheet according to any one of claims 1 to 9, wherein in the slurry forming step, a step in a direction orthogonal to the direction of application is provided on the surface of the coating layer.   The method for producing a ceramic green sheet according to claim 10, wherein the maximum thickness of the coating layer is not more than twice the minimum thickness of the coating layer.   A slurry molding part that forms a flat coating layer by applying a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed on a sheet-like substrate, and the slurry after the slurry molding part The apparatus for producing a ceramic green sheet having a drying furnace for evaporating and removing the volatile dispersion medium, and a peeling part for peeling the slurry from the substrate after the drying furnace, An apparatus for producing a ceramic green sheet, comprising means for adjusting a removal rate of the volatile dispersion medium in the drying furnace by providing a region where the thickness is reduced at a predetermined interval in the coating layer.   A slurry molding part that forms a flat coating layer by applying a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed on a sheet-like substrate, and the slurry after the slurry molding part The apparatus for producing a ceramic green sheet having a drying furnace for evaporating and removing the volatile dispersion medium, and a peeling part for peeling the slurry from the substrate after the drying furnace, An apparatus for producing a ceramic green sheet, comprising means for adjusting a removal rate of the volatile dispersion medium in the drying furnace by disposing a drying prevention member at a predetermined interval on the coating layer surface.   A slurry molding part that forms a flat coating layer by applying a slurry in which an inorganic powder, an organic binder, and a volatile dispersion medium are mixed on a sheet-like substrate, and the slurry after the slurry molding part A drying furnace for evaporating and removing the volatile dispersion medium, and a ceramic green sheet manufacturing apparatus having a peeling part for peeling the slurry from the substrate after the drying furnace, the slurry forming part, An apparatus for producing a ceramic green sheet, comprising: a mechanism for superimposing two sheet-like members as a substrate; and a means for adjusting a removal rate of the volatile dispersion medium in the drying furnace.   The means for adjusting the removal speed includes a first opening through which the volatile dispersion medium evaporated on at least one surface passes, and second and third through which the substrate on which the coating layer is formed passes. The casing having an opening is arranged in the drying furnace, and a removal speed adjusting member having a predetermined opening ratio is attached to the first opening. The manufacturing apparatus of the ceramic green sheet of crab.   The ceramic green sheet manufacturing apparatus according to claim 15, wherein the first opening has an opening ratio of 20% to 50%.   The removal rate adjusting member is a wire mesh having a mesh size of # 200 mesh (screen opening = 0.075 mm) or less and 10 mesh (screen opening = 1.70 mm) or more. Ceramic green sheet manufacturing equipment.   In the said slurry formation process, the maximum thickness of slurry formation thickness is 0.3 mm or more and 1.5 mm or less, The manufacturing apparatus of the ceramic green sheet in any one of Claims 12-17 characterized by the above-mentioned.   The apparatus for producing a ceramic green sheet according to any one of claims 12 to 18, wherein, in the slurry forming step, a step in a direction orthogonal to the direction of application is provided on the surface of the coating layer.   The apparatus for producing a ceramic green sheet according to claim 19, wherein the maximum thickness of the coating film layer is not more than twice the minimum thickness of the coating film layer.

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