Ceramic sheet and method of manufacturing the same

Abstract

To provide a ceramic sheet having excellent catalytic performance.SOLUTION: A manufacturing method of a ceramic sheet includes: a primary sheet molding step of pressing a composition containing resin and an inorganic compound having apatite structure to form a sheet-like molding to obtain a primary sheet; a laminate forming step of laminating a plurality of primary sheets in a thickness direction thereof, or folding or winding the primary sheet to obtain a laminate; a slice step of slicing the lamination body at an angle of 45° or under with respect to the lamination direction to obtain a secondary sheet; and a firing step of firing the secondary sheet.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a ceramic sheet and a method for producing the same. [Background technology]

[0002] Ceramic sheets have been used for a wide range of applications. It is known that various properties of ceramic sheets can be improved by controlling their structure. For example, Patent Document 1 proposes producing a porous ceramic sheet having catalytic properties by preparing a foam slurry containing hydroxyapatite powder, a dispersant, water, a crosslinking agent, a polymerizable resin, a polymerization initiator, and the like, followed by drying and firing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6192090 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the ceramic sheets produced by the above-mentioned conventional methods have room for improvement in catalytic performance. Therefore, an object of the present invention is to provide a ceramic sheet having excellent catalytic performance. [Means for solving the problem]

[0005] The present inventors have conducted extensive research to achieve the above object, and have discovered that a ceramic sheet capable of exhibiting excellent catalytic performance can be obtained by forming a composition containing a resin and an inorganic compound having an apatite structure into a sheet, laminating a plurality of primary sheets in the thickness direction to obtain a laminate, slicing the laminate into secondary sheets, and firing the secondary sheets, thereby completing the present invention.

[0006] The present invention aims to advantageously solve the above-mentioned problems, and provides a ceramic sheet manufacturing method comprising the steps of: a primary sheet forming step of pressing a composition containing a resin and an inorganic compound having an apatite structure into a sheet to obtain a primary sheet; a laminate forming step of stacking a plurality of the primary sheets in the thickness direction or folding or rolling the primary sheets to obtain a laminate; a slicing step of slicing the laminate at an angle of 45° or less to the stacking direction to obtain a secondary sheet; and a firing step of firing the secondary sheet. The ceramic sheet manufacturing method of the present invention can efficiently provide ceramic sheets that can exhibit catalytic performance.

[0007] Here, in the ceramic sheet manufacturing method of the present invention, it is preferable to carry out a degreasing step prior to the firing step in which the secondary sheet is heated in an atmosphere of 300°C to 600°C for 10 minutes or more to degrease it, and to carry out the firing step in an atmosphere of 1000°C or higher. By carrying out the predetermined degreasing step prior to the firing step and adjusting the temperature of the atmosphere during the firing step to be equal to or higher than the predetermined value, the strips can be well bonded to each other, and a high-quality ceramic sheet can be produced. The above temperatures in the degreasing step and the baking step are at 1 atm.

[0008] In the ceramic sheet manufacturing method of the present invention, it is preferable that the proportion of particles having a particle diameter of 0.1 μm or more and 0.5 μm or less in the particle size distribution of the inorganic compound having an apatite structure is 1.5% or more. If the proportion of particles having a particle diameter of 0.1 μm or more and 0.5 μm or less in the particle size distribution of the inorganic compound having an apatite structure is equal to or greater than the above-mentioned predetermined value, the strips are well bonded to each other, and a high-quality ceramic sheet with even more excellent catalytic performance can be manufactured.

[0009] Furthermore, in the ceramic sheet manufacturing method of the present invention, it is preferable that the proportion of particles having a particle diameter of more than 0.5 μm and not more than 15 μm in the particle size distribution of the inorganic compound having an apatite structure is 98.5% or less. If the proportion of particles having a particle diameter of more than 0.5 μm and not more than 15 μm in the particle size distribution of the inorganic compound having an apatite structure is not more than the above-mentioned predetermined value, the strips are well bonded to each other, and a high-quality ceramic sheet with even more excellent catalytic performance can be manufactured.

[0010] In the ceramic sheet manufacturing method of the present invention, the inorganic compound having an apatite structure preferably has a volume average particle size of 0.1 μm to 20 μm. If the volume average particle size of the inorganic compound having an apatite structure is within the above-mentioned range, the strips are well bonded to each other, and a high-quality ceramic sheet with even more excellent catalytic performance can be manufactured. The particle size distribution and volume average particle diameter of the inorganic compound having an apatite structure can be measured using the method described in the examples of this specification.

[0011] In the ceramic sheet manufacturing method of the present invention, the volume fraction of the inorganic compound having an apatite structure in the primary sheet is preferably 50% by volume or more and 75% by volume or less, based on the total volume of the resin and the inorganic compound having an apatite structure. If the volume fraction of the inorganic compound having an apatite structure in the primary sheet is within the above-mentioned range, a ceramic sheet with even better catalytic performance can be manufactured while ensuring sufficiently high adhesion between the strips.

[0012] Furthermore, in the method for producing a ceramic sheet of the present invention, it is preferable that the inorganic compound having an apatite structure contains hydroxyapatite. If hydroxyapatite is used as the inorganic compound having an apatite structure, a ceramic sheet with even more excellent catalytic performance can be produced.

[0013] The present invention also aims to advantageously solve the above-mentioned problems, and the ceramic sheet of the present invention is a ceramic sheet containing an inorganic compound having an apatite structure, and is characterized by satisfying at least one of the following (1) and (2): (1) In X-ray diffraction of the surface of the ceramic sheet, the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane is 0.15 or more. (2) The Raman spectrum of the ceramic sheet is -1 More than 975cm -1 It has peaks in the following ranges: Thus, if a ceramic sheet containing an inorganic compound having an apatite structure satisfies the above-mentioned predetermined conditions for at least one of X-ray diffraction and Raman spectrum, it can exhibit excellent catalytic performance. The ratio I(002) / I(300), which is the ratio of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane in the X-ray diffraction of the surface of the ceramic sheet, and the Raman spectrum of the ceramic sheet can be measured using the method described in the examples of this specification.

[0014] Here, the ceramic sheet of the present invention is formed by joining strips containing the inorganic compound having the apatite structure in parallel, for example.

[0015] Furthermore, the ceramic sheet of the present invention preferably has a porosity of 0.5% or more and 3.5% or less. If the porosity of the ceramic sheet is within the above-mentioned range, the catalytic performance of the ceramic sheet can be further improved. The porosity of the ceramic sheet can be measured using the method described in the examples of this specification.

[0016] Furthermore, in the ceramic sheet of the present invention, the inorganic compound having an apatite structure preferably contains hydroxyapatite. If hydroxyapatite is used as the inorganic compound having an apatite structure, the catalytic performance of the ceramic sheet can be further improved.

[0017] Furthermore, it is preferable that the ceramic sheet of the present invention further satisfies the following (3). (3) The Raman spectrum of the ceramic sheet is -1 Over 955cm -1 There is no peak in the range below. If the Raman spectrum of the ceramic sheet does not have a peak in the above-mentioned predetermined range, the catalytic performance of the ceramic sheet can be further improved. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a ceramic sheet having excellent catalytic performance. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present invention will be described in detail.

[0020] (ceramic sheet) The ceramic sheet of the present invention is a ceramic sheet containing an inorganic compound having an apatite structure, and satisfies predetermined conditions for at least one of X-ray diffraction and Raman spectrum. Specifically, the ceramic sheet of the present invention is characterized by satisfying at least one of the following (1) and (2): (1) In X-ray diffraction of the surface of the ceramic sheet, the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane is 0.15 or more. (2) The Raman spectrum of the ceramic sheet shows a peak at 955 cm -1 More than 975cm -1 It has peaks in the following ranges: Thus, a ceramic sheet containing an inorganic compound having an apatite structure can exhibit excellent catalytic performance by satisfying at least one of the following conditions: (1) the ratio of diffraction intensities I(002) / I(300) in surface X-ray diffraction is a predetermined value or more, and (2) the Raman spectrum has a peak in a predetermined range.

[0021] Here, the ceramic sheet of the present invention may satisfy at least one of the above (1) and (2), but preferably satisfies both of the above (1) and (2).If the ceramic sheet of the present invention satisfies both of the above (1) and (2), it can exhibit even more excellent catalytic performance.

[0022] When the ceramic sheet of the present invention satisfies at least the above (1), the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane in X-ray diffraction of the surface of the ceramic sheet must be 0.15 or more, preferably 0.2 or more, more preferably 0.23 or more, even more preferably 0.26 or more, even more preferably 0.3 or more, even more preferably 0.33 or more, and particularly preferably 0.36 or more. When the ratio I(002) / I(300) of the diffraction intensity in X-ray diffraction of the surface of the ceramic sheet is equal to or greater than the lower limit, the C-axis of the inorganic compound having an apatite structure is oriented on the sheet surface, and the ceramic sheet can exhibit excellent catalytic performance. The upper limit of the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane in X-ray diffraction on the surface of the ceramic sheet is not particularly limited, but is, for example, 0.6 or less. In addition, the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane in the X-ray diffraction of the surface of the ceramic sheet can be controlled by whether or not each process (particularly the lamination process and slicing process) in the ceramic sheet manufacturing method described below is performed, the volume fraction of the resin and inorganic compound having an apatite structure used, and the particle size distribution and volume average particle diameter of the inorganic compound having an apatite structure.However, from the perspective of adjusting the diffraction intensity ratio I(002) / I(300) within the above-mentioned specified range, it is more effective to perform the lamination process and slicing process to align the orientation direction of the inorganic compound having an apatite structure in the secondary sheet before firing in the vertical direction (i.e., the thickness direction of the secondary sheet).

[0023] Furthermore, when the ceramic sheet of the present invention satisfies at least the above (2), the C-axis of the inorganic compound having an apatite structure in the ceramic sheet is oriented on the surface of the sheet, and therefore the ceramic sheet can exhibit excellent catalytic performance.

[0024] Furthermore, the ceramic sheet of the present invention preferably satisfies the following (3) in addition to at least one of the above (1) and (2). (3) The Raman spectrum of the ceramic sheet is -1 Over 955cm -1 There is no peak in the range below. Thus, the Raman spectrum of the ceramic sheet is -1 Over 955cm -1 If the Raman spectrum of the ceramic sheet does not have a peak in the range of less than 940 cm, it is presumed that the crystalline structure of the inorganic compound having an apatite structure is well maintained in the ceramic sheet, and the catalytic performance of the ceramic sheet can be further improved. -1 Over 955cm -1 If there is a peak in the range below this, isomers of the inorganic compound containing the apatite structure may be produced, resulting in a decrease in the catalytic performance of the ceramic sheet.

[0025] <Inorganic compounds with apatite structure> The inorganic compound having an apatite structure contained in the ceramic sheet of the present invention is a phosphate mineral having a crystalline structure classified as a hexagonal system, and is also called apatite. The inorganic compound having an apatite structure is not particularly limited, but examples thereof include compounds represented by the formula (I): Ca x (PO4) y M 2x-3y [In formula (I), x and y satisfy x>0, y>0, 2x-3y>0, and M represents a halogen atom such as F or Cl, or a hydroxyl group (OH)] can be used. The molar ratio of Ca to P in the inorganic compound having an apatite structure (Ca / P, i.e., the ratio of x to y in the above formula (I), x / y) is preferably 1.50 or more and 2.50 or less. If the molar ratio of Ca to P is 2.50 or less, the inorganic compound having an apatite structure can maintain its crystalline structure well, and the catalytic performance of the ceramic sheet can be ensured to be sufficiently high. The specific gravity of the inorganic compound having an apatite structure is not particularly limited, but is, for example, 3.1 or more and 3.2 or less.

[0026] From the viewpoint of further improving the catalytic performance of the produced ceramic sheet, it is preferable to use, as the inorganic compound having an apatite structure, an inorganic compound in which M in the above formula (I) is a hydroxyl group (OH), i.e., hydroxyapatite. Hydroxyapatite (sometimes called "hydroxyapatite", "HAP", etc.) has the general formula, for example, Ca 10-z (PO4) 6-z (HPO4) z (OH)2, Ca 10 It can also be expressed as (PO4)6(OH)2, Ca5(PO4)3(OH), etc., but it is known that depending on the conditions of the production method, etc., different hydroxyapatites can be produced with different molar ratios of Ca to P (Ca / P, i.e., the ratio of x to y in the above formula (I), x / y) in the range of 1.55 to 2.5.

[0027] <Porosity> The porosity of the ceramic sheet of the present invention is preferably 0.5% or more, more preferably 1% or more, even more preferably 1.5% or more, even more preferably 2% or more, and preferably 3.5% or less, more preferably 3.0% or less, even more preferably 2.8% or less, even more preferably 2.6% or less, and even more preferably 2.4% or less. If the porosity of the ceramic sheet is above the above-mentioned lower limit, the adhesion between the strips in the ceramic sheet can be sufficiently high, peeling between the strips can be suppressed, and the catalytic performance of the ceramic sheet can be further improved. On the other hand, if the porosity of the ceramic sheet is below the above-mentioned upper limit, the catalytic performance of the ceramic sheet can be sufficiently high, and the adhesion between the strips in the ceramic sheet can be improved, and peeling between the strips can be further suppressed. The porosity of the ceramic sheet can be controlled by the volume fractions of the resin and the inorganic compound having an apatite structure used in the ceramic sheet manufacturing method described below, the particle size distribution and volume average particle diameter of the inorganic compound having an apatite structure, the strength of kneading during manufacturing, etc. Among these, the volume fraction of the inorganic compound has a particularly large effect.

[0028] (Method of manufacturing ceramic sheets) The ceramic sheet of the present invention having the above-described characteristics can be efficiently produced according to the ceramic sheet manufacturing method of the present invention. The ceramic sheet manufacturing method of the present invention is characterized by including the following steps: a primary sheet forming step in which a composition containing a resin and an inorganic compound having an apatite structure is pressed into a sheet to obtain a primary sheet; a laminate forming step in which multiple primary sheets are stacked in the thickness direction or folded or rolled up to obtain a laminate; a slicing step in which the laminate is sliced ​​at an angle of 45° or less relative to the stacking direction to obtain a secondary sheet; and a firing step in which the secondary sheet is fired. Furthermore, the manufacturing method of the present invention preferably includes a degreasing step in which the secondary sheet is heated in an atmosphere of 300°C to 600°C for 10 minutes or more to degrease it prior to the firing step. Each step is described below.

[0029] <Primary sheet molding process> In the primary sheet forming step, a composition containing a resin and an inorganic compound having an apatite structure is pressed and formed into a sheet to obtain a primary sheet.

[0030] [Composition] Here, the composition can be prepared by mixing a resin, an inorganic compound having an apatite structure, and any other components.

[0031] - Inorganic compound with apatite structure - As the inorganic compound having an apatite structure used in preparing the composition, the above-mentioned inorganic compounds having an apatite structure that can be contained in the ceramic sheet of the present invention can be used. The inorganic compound having an apatite structure used in preparing the composition is not particularly limited, but is preferably in the form of particles. When an inorganic compound having a particulate apatite structure is used, in order to adjust the particle size distribution and volume average particle diameter of the inorganic compound having a particulate apatite structure within the desired ranges described below, the inorganic compound having an apatite structure may be subjected to a dispersion treatment prior to preparation of the composition, and the obtained dispersion of the inorganic compound having an apatite structure may be used in preparation of the composition.

[0032] In the particle size distribution of the inorganic compound having an apatite structure used to prepare the composition (i.e., in the composition), the proportion of particles having a particle diameter of 0.1 μm to 0.5 μm is preferably 1.5% or more, more preferably 4% or more, even more preferably 8% or more, even more preferably 12% or more, even more preferably 16% or more, and preferably 50% or less, more preferably 45% or less, even more preferably 40% or less, even more preferably 35% or less, and even more preferably 30% or less. If the proportion of particles having a particle diameter of 0.1 μm to 0.5 μm in the particle size distribution of the inorganic compound having an apatite structure in the composition is above the lower limit, the catalytic performance of the ceramic sheet produced can be further improved and the strips of the ceramic sheet can be well bonded to each other. On the other hand, if the proportion of particles having a particle diameter of 0.1 μm to 0.5 μm in the particle size distribution of the inorganic compound having an apatite structure in the composition is below the upper limit, the catalytic performance of the ceramic sheet produced can be further improved.

[0033] Furthermore, in the particle size distribution of the inorganic compound having an apatite structure used to prepare the composition (i.e., in the composition), the proportion of particles having a particle size of more than 0.5 μm and not more than 15 μm is preferably 50% or more, more preferably 55% or more, even more preferably 60% or more, even more preferably 65% ​​or more, even more preferably 75% or more, and preferably 98.5% or less, more preferably 96% or less, even more preferably 92% or less, even more preferably 88% or less, and even more preferably 84% or less. If the proportion of particles having a particle size of more than 0.5 μm and not more than 15 μm in the particle size distribution of the inorganic compound having an apatite structure in the composition is above the lower limit, the catalytic performance of the produced ceramic sheet can be further improved. On the other hand, if the proportion of particles having a particle size of more than 0.5 μm and not more than the upper limit, the catalytic performance of the produced ceramic sheet can be further improved and the strips of the ceramic sheet can be well bonded to each other.

[0034] Furthermore, the volume average particle diameter of the inorganic compound having an apatite structure used in preparing the composition (i.e., in the composition) is preferably 0.1 μm or more, more preferably 0.2 μm or more, even more preferably 0.4 μm or more, even more preferably 0.6 μm or more, even more preferably 0.8 μm or more, and preferably 20 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, even more preferably 3 μm or less, and even more preferably 1.5 μm or less. On the other hand, if the volume average particle diameter of the inorganic compound having an apatite structure in the composition is above the above-mentioned lower limit, the catalytic performance of the produced ceramic sheet can be further improved. If the volume average particle diameter of the inorganic compound having an apatite structure in the composition is below the above-mentioned upper limit, the catalytic performance of the produced ceramic sheet can be further improved and the strips of the ceramic sheet can be well bonded to each other.

[0035] The particle size distribution and volume average particle size of the inorganic compound having an apatite structure in the composition can be controlled by the conditions of the dispersion treatment described above.

[0036] -resin- The resin is not particularly limited, and various resins can be used. Examples of such resins include polyethylene-based crystalline resins such as linear or branched high-density polyethylene, low-density polyethylene, and ultra-high molecular weight polyethylene, polypropylene-based crystalline resins such as linear or branched high-density polypropylene and low-density polypropylene, polyolefin-based crystalline resins represented by the group consisting of polymethylpentene, polybutene, polymethylbutene, polymethylhexene, polyvinylnaphthalene, and polyxylene, polyester-based crystalline resins represented by the group consisting of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate, and aromatic polyester, polyamide-based crystalline resins represented by the group consisting of nylon-6, nylon-66, nylon-12, and polyamideimide, polyvinylidene fluoride, polytetrafluoroethylene, and the like. Examples of suitable crystalline resins include fluororesins such as ethylene, rosin resins, polyvinylidene chloride, polyacrylonitrile, syndiotactic polystyrene, polyoxymethylene, polyphenylene sulfide (PPS), polyether ether ketone (PEEK), cellulose, acetal resins, chlorinated polyethers, ethylene-vinyl acetate copolymers, and liquid crystal polymers (aromatic polycyclic condensation polymers); as well as elastomers such as acrylonitrile butadiene rubber (also known as "nitrile rubber" or "NBR"), styrene-butadiene-styrene block copolymers, styrene-ethylene-butylene-styrene copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-propylene-styrene copolymers, silicone rubber, and fluororubber. Among these, acrylonitrile butadiene rubber is preferred.

[0037] -Other ingredients- The composition used in the primary sheet forming step may optionally further contain components other than the above-mentioned resin and inorganic compound having an apatite structure.

[0038] -Preparation of composition- The mixing of the above-mentioned components can be carried out using known mixing devices such as kneaders, mixers such as Henschel mixers, Hobart mixers, and high-speed mixers, twin-screw kneaders, and roll mixers. Mixing may also be carried out in the presence of a solvent. The resin may be dissolved or dispersed in a solvent in advance to form a resin solution, which may then be mixed with an inorganic compound having an apatite structure and any other components. The mixing time may be, for example, 5 minutes to 60 minutes. The mixing temperature may be, for example, 5°C to 160°C.

[0039] [Molding of the composition] The composition prepared as described above can be optionally degassed and crushed, and then pressed to form into a sheet. The sheet formed by pressing the composition in this manner can be used as a primary sheet. If a solvent is used during mixing, it is preferable to remove the solvent before forming into a sheet. For example, if degassing is performed using vacuum degassing, the solvent can be removed simultaneously during degassing.

[0040] Here, the composition can be formed into a sheet using any known forming method, such as press forming, rolling forming, or extrusion forming, without any particular limitation, as long as the forming method involves applying pressure.

[0041] [Primary sheet] In the primary sheet obtained by pressing the composition into a sheet, it is presumed that the inorganic compound having an apatite structure is aligned mainly in the in-plane direction.

[0042] The thickness of the primary sheet is preferably 2.5 mm or less, more preferably 2.0 mm or less, and even more preferably 1.5 mm or less. If the thickness of the primary sheet is equal to or less than the above upper limit, cracks or breakage of the sheet due to shrinkage in the subsequent firing step can be effectively suppressed, making it possible to efficiently form a ceramic sheet. The lower limit of the thickness of the primary sheet is not particularly limited, but can be, for example, 0.1 mm or more.

[0043] The volume fraction of the inorganic compound having an apatite structure in the primary sheet is preferably 50% by volume or more, more preferably 53% by volume or more, even more preferably 57% by volume or more, and preferably 75% by volume or less, more preferably 70% by volume or less, and even more preferably 65% ​​by volume or less, based on 100% by volume of the total volume of the resin and the inorganic compound having an apatite structure. If the volume fraction of the inorganic compound having an apatite structure in the primary sheet is above the lower limit, the catalytic performance of the ceramic sheet produced can be further improved and the pieces of the ceramic sheet can be well bonded to each other. On the other hand, if the volume fraction of the inorganic compound having an apatite structure in the primary sheet is below the upper limit, the catalytic performance of the ceramic sheet produced can be further improved and the adhesiveness between the pieces of the ceramic sheet can be sufficiently high.

[0044] The volume fraction of the resin in the primary sheet is preferably 25% by volume or more, more preferably 30% by volume or more, even more preferably 35% by volume or more, and preferably 50% by volume or less, more preferably 47% by volume or less, and even more preferably 43% by volume or less, based on 100% by volume of the total volume of the resin and the inorganic compound having an apatite structure. If the volume fraction of the resin in the primary sheet is above the lower limit, the catalytic performance of the ceramic sheet produced can be further improved and the adhesiveness between the ceramic sheet pieces can be sufficiently high. On the other hand, if the volume fraction of the resin in the primary sheet is below the upper limit, the catalytic performance of the ceramic sheet produced can be further improved and the adhesiveness between the ceramic sheet pieces can be sufficiently high.

[0045] <Laminate formation process> In the laminate formation process, a laminate is obtained by stacking multiple primary sheets in the thickness direction, or by folding or winding the primary sheets. Here, the formation of the laminate by folding the primary sheets is not particularly limited and can be performed by folding the primary sheets at a fixed width using a folding machine. Furthermore, the formation of the laminate by winding the primary sheets is not particularly limited and can be performed by winding the primary sheets around an axis parallel to the short or long direction of the primary sheets. Furthermore, the formation of the laminate by stacking the primary sheets can be performed using a lamination device without particular limitations. For example, using a sheet lamination device (manufactured by Nikkiso Co., Ltd., product name "Hi-Stacker") can prevent air from entering between the layers, allowing a good laminate to be obtained efficiently.

[0046] In the lamination step, it is preferable to apply pressure (secondary pressure) to the obtained laminate in the lamination direction while heating it. By applying secondary pressure to the laminate in the lamination direction while heating it, it is possible to promote fusion bonding between the laminated primary sheets.

[0047] The pressure applied to the laminate in the stacking direction can be 0.05 MPa or more and 0.50 MPa or less. The heating temperature of the laminate is not particularly limited, but is preferably 50° C. or more and 170° C. or less. The heating time of the laminate can be, for example, 10 seconds or more and 30 minutes or less.

[0048] In a laminate obtained by stacking, folding, or rolling the primary sheets, the inorganic compound having an apatite structure is presumably oriented in a direction substantially perpendicular to the stacking direction. For example, when the inorganic compound having an apatite structure is in the form of particles, the direction of the long axis of the particles of the inorganic compound having an apatite structure is presumably substantially perpendicular to the stacking direction.

[0049] <(iii) Slicing step> In the slicing step, the laminate obtained in the above step is sliced ​​at an angle of 45° or less relative to the lamination direction to obtain a secondary sheet. The method for slicing the laminate is not particularly limited, and examples thereof include the multi-blade method, laser processing method, water jet method, and knife processing method. Among these, the knife processing method is preferred because it is easy to make the thickness of the secondary sheet uniform. The cutting tool used to slice the laminate is not particularly limited, and a slicing member having a smooth plate surface with a slit and a blade protruding from the slit (for example, a plane or slicer with a sharp blade) can be used.

[0050] Furthermore, from the viewpoint of further enhancing the catalytic performance of the resulting ceramic sheet, the angle at which the laminate is sliced ​​is preferably 30° or less relative to the stacking direction, more preferably 15° or less relative to the stacking direction, and preferably approximately 0° relative to the stacking direction (i.e., in the direction along the stacking direction).

[0051] It is presumed that in the secondary sheet obtained in this manner, the inorganic compound having an apatite structure is well oriented in the thickness direction.

[0052] <Degreasing process> In the optional degreasing step, the secondary sheet is heated to degrease it. The lower limit of the atmosphere temperature in the degreasing step is preferably 300°C or higher, more preferably 350°C or higher, and even more preferably 400°C or higher. The upper limit of the atmosphere temperature in the degreasing step must be lower than the atmosphere temperature in the firing step described below, and is preferably 600°C or lower, more preferably 550°C or lower, and even more preferably 500°C or lower. If the atmosphere temperature in the degreasing step is above the lower limit, the degreasing step can be performed without leaving any resin contained in the secondary sheet, and the pieces can be well bonded together, resulting in the production of a high-quality ceramic sheet. On the other hand, if the atmosphere temperature in the degreasing step is below the upper limit, the degreasing step can be performed without carbonizing the resin contained in the secondary sheet, and the pieces can be well bonded together, resulting in the production of a high-quality ceramic sheet. Furthermore, the heating time in the degreasing step is preferably 10 minutes or more, preferably 1 hour or more, preferably 24 hours (1 day) or more, more preferably 36 hours (1.5 days) or more, even more preferably 48 hours (2 days) or more, preferably 240 hours (10 days) or less, and more preferably 120 hours (5 days) or less. If the heating time in the degreasing step is above the lower limit, the degreasing step can be performed without leaving any resin contained in the secondary sheet, and the pieces can be well bonded together, resulting in the production of a high-quality ceramic sheet. On the other hand, if the heating time in the degreasing step is below the upper limit, the degreasing step can be performed without carbonizing the resin contained in the secondary sheet, and the pieces can be well bonded together, resulting in the production of a high-quality ceramic sheet.

[0053] Here, the degreasing step is preferably carried out under an atmosphere of an inert gas (for example, nitrogen gas, argon gas, etc.) at normal pressure (1 atm).

[0054] <Firing process> In the firing step, the secondary sheet is fired. The atmosphere temperature in the firing step is preferably 600°C or higher, more preferably 800°C or higher, even more preferably 1000°C or higher, even more preferably 1100°C or higher, and preferably 2000°C or lower, more preferably 1800°C or lower, even more preferably 1500°C or lower, even more preferably 1300°C or lower, and even more preferably 1250°C or lower. If the atmosphere temperature in the firing step is above the above-mentioned lower limit, the inorganic compound having an apatite structure can be sintered more densely, the strips can be bonded well, and a high-quality ceramic sheet can be produced. On the other hand, if the atmosphere temperature in the firing step is below the above-mentioned upper limit, the crystalline structure of the inorganic compound having an apatite structure can be prevented from changing and producing undesirable isomers, etc., thereby ensuring sufficiently high catalytic performance of the produced ceramic sheet. Furthermore, the firing time in the firing step is preferably 12 hours (0.5 days) or more, more preferably 24 hours (1 day) or more, preferably 48 hours (2 days) or less, and more preferably 36 hours or less (1.5 days). If the firing time is above the lower limit, the inorganic compound having an apatite structure can be sintered more densely, the strips can be well bonded to each other, and a high-quality ceramic sheet can be produced. On the other hand, if the firing time is below the upper limit, the crystalline structure of the inorganic compound having an apatite structure can be well maintained, and the catalytic performance of the produced ceramic sheet can be ensured to be sufficiently high.

[0055] Here, the firing step is preferably carried out in an atmosphere of an inert gas (such as nitrogen gas or argon gas) at normal pressure (1 atm), similar to the degreasing step.

[0056] According to the manufacturing method of the present invention including the steps described above, it is possible to efficiently manufacture the ceramic sheet of the present invention, i.e., a ceramic sheet containing an inorganic compound having an apatite structure, which satisfies the above-mentioned predetermined conditions for at least one of X-ray diffraction and Raman spectrum.

[0057] As described above, the ceramic sheet manufacturing method of the present invention includes a firing step, and therefore the ceramic sheet manufactured by the ceramic sheet manufacturing method of the present invention is composed of a sintered body of an inorganic compound having an apatite structure. Therefore, the inorganic compound having an apatite structure used in the ceramic sheet manufacturing method of the present invention, i.e., the inorganic compound having an apatite structure contained in the composition described above, and the inorganic compound having an apatite structure contained in the ceramic sheet manufactured by the ceramic sheet manufacturing method of the present invention, i.e., the sintered body of the inorganic compound having an apatite structure, may differ in shape, etc. For example, even if a particulate inorganic compound having an apatite structure is used in the ceramic sheet manufacturing method of the present invention, the inorganic compound having an apatite structure (sintered body of the inorganic compound having an apatite structure) contained in the manufactured ceramic sheet may be in a shape other than particulate.

[0058] Furthermore, the ceramic sheet manufactured using the ceramic sheet manufacturing method of the present invention described above is composed of strips containing an inorganic compound having an apatite structure joined in parallel. For example, the ceramic sheet manufactured using the ceramic sheet manufacturing method of the present invention is composed of a plurality of strips made of a sintered body of an inorganic compound having an apatite structure, and the plurality of strips are joined in the width direction (i.e., along their long sides).

[0059] The ceramic sheet used to produce the ceramic sheet of the present invention may contain small amounts of components (other components) other than the inorganic compound having an apatite structure, as long as the desired effects of the present invention are obtained. For example, the ceramic sheet of the present invention produced by the ceramic sheet manufacturing method of the present invention may contain small amounts of other components, such as isomers produced by changes in the crystal structure of inorganic compounds having an apatite structure, and components derived from resins used during production. [Example]

[0060] The present invention will be specifically described below based on examples, but the present invention is not limited to these examples. In the following description, "%" and "parts" representing amounts are based on mass unless otherwise specified.

[0061] In each of the examples and comparative examples, various attributes and evaluations were measured or evaluated according to the following methods.

[0062] <Particle size distribution and volume average particle diameter D50> 1 g of hydroxyapatite (undispersed inorganic compound) or 1 g of the hydroxyapatite dispersion prepared in each manufacturing example was placed in water as a solvent and uniformly dispersed to obtain a suspension. Next, the particle size of the hydroxyapatite contained in the suspension was measured using a laser diffraction / scattering particle size distribution analyzer (Horiba, Ltd., model "LA960"). A particle size distribution curve was then created, with the obtained particle size on the horizontal axis and the volume-equivalent particle frequency on the vertical axis. Based on the obtained particle size distribution curve, the proportion of particles having a particle size of 0.1 μm or more and 0.5 μm or less (hereinafter sometimes referred to as the "first region") in the particle size distribution of hydroxyapatite, and the proportion of particles having a particle size of more than 0.5 μm and 15.0 μm or less (hereinafter sometimes referred to as the "second region") were calculated. In addition, in the obtained particle size distribution (volume basis), the particle diameter (D50) at which the cumulative volume calculated from the smallest diameter side becomes 50% was determined, and this was taken as the volume-average particle diameter of hydroxyapatite.

[0063] <Porosity> Regarding the obtained ceramic sheet, the specific gravity was measured using an automatic pycnometer (manufactured by Toyo Seiki Co., Ltd., product name "DENSIMETER-H"). Using the actually measured value of the obtained specific gravity, the porosity of the ceramic sheet was calculated by the following formula. Porosity = 1 - {(actually measured value of specific gravity) ÷ (theoretical specific gravity)} [%] In the above formula, as the theoretical specific gravity, the specific gravity value of hydroxyapatite (= 3.2) was used.

[0064] <X-ray Diffraction> X-ray diffraction of the surface of the ceramic sheet was performed using "X’ Pert PRO MPD" manufactured by PANalytical. From the obtained peaks, using the peak height (diffraction intensity) of 2Θ = 25.88 degrees corresponding to the (002) plane and the peak height (diffraction intensity) of 2Θ = 32.90 degrees corresponding to the (300) plane, the value of the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane was calculated.

[0065] <Raman Peak> Using a microscopic laser Raman spectrophotometer (Nicolet Almega XR manufactured by Thermo Fisher Scientific K.K.), the ceramic sheet was measured. Then, regarding the obtained Raman spectrum, the presence or absence of peaks observed within the range of 940 cm -1 or more and 955 cm -1 or less, and the presence or absence of peaks observed within the range of 955 cm -1 or more and 975 cm -1 or less were confirmed.

[0066] <Separation of Stripes> The obtained ceramic sheet was visually confirmed, and the separation of stripes was evaluated according to the following criteria. In the firing process of the manufacturing method of the ceramic sheet, when the firing shrinkage of the secondary sheet is large, a problem of peeling between the stripes occurs. The less the peeling between the stripes in the ceramic sheet, the higher the quality of the ceramic sheet. A: The stripes are not peeled off, and the ceramic sheet is maintained as a single sheet. B: Strips have peeled off in one or two places, and the ceramic sheet has separated into two or three pieces. C: Strips have peeled off in three or more places, and the ceramic sheet has separated into four or more parts.

[0067] <Catalyst performance> The resulting ceramic sheet was used to bake the rubber sheet containing graphite under certain conditions, and it was determined that the lower the organic matter content after baking, the more effectively the organic matter was removed, and the better the ceramic sheet functioned as a catalyst. Specifically, the catalytic performance of the ceramic sheet was evaluated according to the following method. 210 parts of nitrile rubber (NBR) (manufactured by Nippon Zeon Co., Ltd., product name "Nipol 1312") that is liquid at room temperature and normal pressure, 90 parts of nitrile rubber (NBR) (manufactured by Nippon Zeon Co., Ltd., product name "Nipol 3350") that is solid at room temperature and normal pressure, and 820 parts of flake graphite (manufactured by Nippon Graphite Industries Co., Ltd., product name "UP20α", volume average particle diameter: 20 μm, aspect ratio = 10) as a particulate carbon material (equivalent to 364 parts by volume per 300 parts by volume of the resin used) were mixed and stirred at 150°C for 20 minutes using a pressure kneader (manufactured by Nippon Spindle Co., Ltd.). The resulting kneaded material was stretched using a constant speed roll to produce a rubber sheet with a thickness of 1 mm, and this was then punched into a circle with a diameter of 2 cm to prepare a test specimen. The obtained test specimen was sandwiched between the ceramic sheets prepared in each Example from above and below, and fired at 300°C for 4 hours in a nitrogen atmosphere to obtain a fired sample. The resulting fired samples were subjected to thermogravimetry (TGA) in an oxygen atmosphere at temperatures ranging from 30 to 1000°C at a heating rate of 10°C / min. The weight loss rate from the starting point to 600°C [= (weight loss from the starting point to 600°C / weight of fired sample at the start of measurement) × 100] [%] was taken as the organic matter content in the fired sample and evaluated according to the following criteria. The lower the organic matter content, the higher the catalytic performance of the ceramic sheet. A: Resin-derived components are less than 20% B: Resin-derived components are 20% or more but less than 25% C: Resin-derived components are 25% or more and less than 30% D: Resin-derived components are 30% or more

[0068] (Production Example 1) 500 g of distilled water and 500 g of hydroxyapatite (HAP, manufactured by Taihei Chemical Industry Co., Ltd., product name "HAP-200," volume average particle diameter D50: 8 μm, first region particle ratio = 1.5%, second region particle ratio = 98.5%, Ca to P molar ratio (Ca / P) = 1.57, specific gravity: 3.2) were placed in a glass container, and 1000 g of glass beads (particle diameter = 1.0 mm) were added to prepare a sample. The glass container was then dispersed in a bead disperser (manufactured by Asada Iron Works Co., Ltd., product name "Paint Shaker," vibration frequency = 643 rpm) for 3 minutes. The obtained slurry was filtered, and the distilled water was removed to obtain hydroxyapatite dispersion 1. The obtained hydroxyapatite dispersion 1 had a volume average particle diameter D50 of 2 μm, a ratio of first region particles of 6.3%, and a ratio of second region particles of 93.7%.

[0069] (Production Example 2) Hydroxyapatite Dispersion (2) was obtained by the same procedure as in Production Example 1, except that the dispersion time in Production Example 1 was changed from 3 minutes to 5 minutes. The volume average particle diameter D50 of the obtained hydroxyapatite dispersion (2) was 1 μm, the proportion of particles in the first region was 20.7%, and the proportion of particles in the second region was 79.3%.

[0070] Example 1 <Primary sheet molding process> <<Preparation of Composition>> As the resin, 70 parts of nitrile rubber (NBR) (manufactured by Nippon Zeon Co., Ltd., product name "Nipol 1312") that is liquid at room temperature and normal pressure and 30 parts of nitrile rubber (NBR) (manufactured by Nippon Zeon Co., Ltd., product name "Nipol 3350") that is solid at room temperature and normal pressure were mixed with 390 parts of non-dispersed hydroxyapatite (HAP, manufactured by Taihei Chemical Industry Co., Ltd., product name "HAP-200", volume average particle diameter D50: 8 μm, proportion of first region particles = 1.5%, proportion of second region particles = 98.5%) as the ceramic material, and the mixture was stirred and mixed at a temperature of 150°C for 20 minutes using a pressure kneader (manufactured by Nippon Spindle Co., Ltd.).

[0071] <<Primary sheet molding>> Next, 50 g of the obtained composition was sandwiched between sandblasted PET films (protective films) having a thickness of 50 μm, and roll-molded (primary pressing) under the conditions of a roll gap of 1000 μm, a roll temperature of 50°C, a roll linear pressure of 50 kg / cm, and a roll speed of 1 m / min to obtain a primary sheet having a thickness of 1 mm.

[0072] <Laminate formation process> Next, the primary sheets obtained above were cut into 150 mm length x 150 mm width x 0.8 mm thickness, and 188 sheets were stacked in the thickness direction of the primary sheets.Furthermore, they were pressed (secondary pressing) in the stacking direction at a temperature of 120°C and a pressure of 0.1 MPa for 3 minutes to obtain a laminate with a height of approximately 150 mm.

[0073] <Slicing process> Then, while pressing the laminated side of the secondarily pressurized laminate with a pressure of 0.3 MPa, a woodworking slicer (manufactured by Marunaka Iron Works, product name "Super Finishing Planer Super Mecha S") was used to slice at an angle of 0 degrees to the lamination direction (in other words, in the normal direction to the main surface of the laminated primary sheet), thereby obtaining a secondary sheet measuring 150 mm in length, 150 mm in width, and 0.30 mm in thickness.

[0074] <Degreasing process - baking process> The obtained secondary sheet was then heated at 400°C for 3 days in a nitrogen atmosphere at normal pressure to perform a degreasing process and burn off the resin components (degreasing process), and then the temperature was raised to 1150°C at a rate of 10°C / min in the same atmosphere and fired for 1 day (firing process). The obtained ceramic sheet was subjected to various measurements and evaluations, and the results are shown in Table 1.

[0075] Example 2 A ceramic sheet was produced in the same manner as in Example 1, except that the amount of hydroxyapatite added during the preparation of the composition in the primary sheet molding step of Example 1 was changed from 390 parts to 480 parts, and various measurements and evaluations were carried out. The results are shown in Table 1.

[0076] Example 3 A ceramic sheet was produced in the same manner as in Example 2, except that in the primary sheet molding step of Example 2, 480 parts of the hydroxyapatite dispersion (1) prepared in Production Example 1 was added instead of 480 parts of non-dispersed hydroxyapatite during the preparation of the composition, and various measurements and evaluations were carried out. The results are shown in Table 1.

[0077] Example 4 A ceramic sheet was produced in the same manner as in Example 2, except that in the primary sheet molding step of Example 2, 480 parts of the hydroxyapatite dispersion (2) prepared in Production Example 2 was added instead of 480 parts of the undispersed hydroxyapatite when preparing the composition, and various measurements and evaluations were carried out. The results are shown in Table 1.

[0078] Example 5 A ceramic sheet was produced and various measurements and evaluations were carried out in the same manner as in Example 2, except that the firing temperature was changed from 1150° C. to 1350° C. in the firing step of Example 2. The results are shown in Table 1.

[0079] Example 6 A ceramic sheet was produced in the same manner as in Example 2, except that the secondary sheet obtained in the slicing step in Example 2 was subjected to the firing step without being subjected to the degreasing step, and various measurements and evaluations were carried out. The results are shown in Table 1.

[0080] (Comparative Example 1) A ceramic sheet was manufactured in the same manner as in Example 1, except that the primary sheet obtained in the primary sheet molding step of Example 1 was directly subjected to the degreasing step and firing step without being subjected to the laminate forming step and slicing step. Various measurements and evaluations were carried out. The results are shown in Table 1.

[0081] [Table 1]

[0082] From Table 1, it can be seen that the ceramic sheets of Examples 1 to 6, which were manufactured through a process of obtaining a primary sheet using a composition containing a resin and an inorganic compound having an apatite structure (primary sheet forming process), a process of forming a laminate by stacking the primary sheets, etc. (laminate forming process), a process of slicing the laminate to obtain a secondary sheet (slicing process), and a process of firing the secondary sheet (firing process), satisfy the specified conditions for at least one of X-ray diffraction and Raman spectrum, and are therefore able to exhibit excellent catalytic performance. On the other hand, the ceramic sheet of Comparative Example 1, which was manufactured without undergoing the laminate forming step and slicing step, did not satisfy the predetermined conditions for either X-ray diffraction or Raman spectrum, and was found to have inferior catalytic performance. [Industrial Applicability]

[0083] According to the present invention, it is possible to provide a ceramic sheet having excellent catalytic performance.

Claims

1. a primary sheet forming step of pressurizing a composition containing a resin and an inorganic compound having an apatite structure to form it into a sheet to obtain a primary sheet; a laminate forming step of laminating a plurality of the primary sheets in the thickness direction or folding or rolling the primary sheets to obtain a laminate; a slicing step of slicing the laminate at an angle of 45° or less with respect to the lamination direction to obtain a secondary sheet; and a firing step of firing the secondary sheet.

2. Prior to the firing step, a degreasing step is carried out in which the secondary sheet is heated in an atmosphere of 300°C or higher and 600°C or lower for 10 minutes or longer to degrease the secondary sheet, The method for producing a ceramic sheet according to claim 1 , wherein the firing step is carried out in an atmosphere of 1000° C. or higher.

3. 3. The method for producing a ceramic sheet according to claim 1, wherein the inorganic compound having an apatite structure has a particle size distribution in which the proportion of particles having a particle diameter of 0.1 μm or more and 0.5 μm or less is 1.5% or more.

4. The method for producing a ceramic sheet according to any one of claims 1 to 3, wherein in the particle size distribution of the inorganic compound having an apatite structure, the proportion of particles having a particle diameter of more than 0.5 µm and not more than 15 µm is 98.5% or less.

5. The method for producing a ceramic sheet according to any one of claims 1 to 4, wherein the inorganic compound having an apatite structure has a volume average particle size of 0.1 µm or more and 20 µm or less.

6. The method for producing a ceramic sheet according to any one of claims 1 to 5, wherein a volume fraction of the inorganic compound having an apatite structure in the primary sheet is 50 volume % or more and 75 volume % or less, based on a total volume of the resin and the inorganic compound having an apatite structure.

7. The method for producing a ceramic sheet according to any one of claims 1 to 6, wherein the inorganic compound having an apatite structure contains hydroxyapatite.

8. A ceramic sheet containing an inorganic compound having an apatite structure, A ceramic sheet that satisfies both of the following (1) and (2): (1) In X-ray diffraction of the surface of the ceramic sheet, the ratio I(002) / I(300) of the diffraction intensity of the (002) plane to the diffraction intensity of the (300) plane is 0.15 or more and 0.6 or less. (2) The Raman spectrum of the ceramic sheet is －１ 975cm or more －１ It has peaks in the following ranges:

9. 9. The ceramic sheet according to claim 8, wherein strips containing the inorganic compound having an apatite structure are joined in parallel.

10. 10. The ceramic sheet according to claim 8, wherein the porosity is 0.5% or more and 3.5% or less.

11. The ceramic sheet according to any one of claims 8 to 10, wherein the inorganic compound having an apatite structure contains hydroxyapatite.

12. The ceramic sheet according to any one of claims 8 to 11, further satisfying the following (3): (3) The Raman spectrum of the ceramic sheet is －１ Over 955cm －１ There is no peak in the range below.

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