Method for producing ceramic porous laminate

Abstract

The purpose of the present invention is to provide a method for producing a laminate by forming a layer having a uniform thickness on a layer to be a base material, using a simple method. The present invention pertains to a method for producing a ceramic porous laminate by forming a ceramic porous layer on a tube inner surface of a ceramic porous body having at least one tube, the method comprising: a slurry liquid supply step (1) for supplying, to the inside of the tube, a slurry liquid containing inorganic particles; and a coating film layer formation step (2) for forming a coating film layer of the slurry liquid on the inner surface of the tube by passing a jig into the tube, while supplying the slurry liquid or after supplying the slurry liquid.

Description

Method for manufacturing porous ceramic laminate

[0001] The present invention relates to a method for producing a porous ceramic laminate.

[0002] Porous ceramic bodies are used in various fields as membranes that have functions such as separating, concentrating, or filtering gaseous or liquid fluids, such as microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, ion exchange membranes, and gas separation membranes.

[0003] It is important that porous ceramic bodies suitable for use in the fields described above be able to fully perform functions such as separation while allowing fluids to flow easily through the porous ceramic body. Therefore, they are usually composed of a laminate of two or more layers, including a functional layer with a small pore diameter and a support layer with a large pore diameter that supports the functional layer.

[0004] For example, Patent Document 1 discloses a method for manufacturing a multi-layer filter in which a filtration membrane is attached to a porous support. In Patent Document 1, the porous support is immersed in a liquid to degas the air in the pores of the porous support, and the end of the porous support containing the liquid in the pores is airtightly sealed, and then a suspension containing a powder for forming a filtration membrane is brought into fluid contact with one side of the porous support, and the other side of the porous support is maintained at a lower pressure than the side with which the suspension contacts, and the fluid contact of the suspension is continued for a predetermined time to attach a filtration membrane made of the powder to one side of the porous support, and then a predetermined operation is performed, followed by firing to manufacture a multi-layer filter.

[0005] Furthermore, Patent Document 2 discloses a method in which a ceramic sol liquid is poured into the cells of a porous substrate and allowed to flow through the cells, thereby adhering the ceramic sol onto the surfaces of the cells.

[0006] Japanese Patent Publication No. 63-66566 Japanese Patent Laid-Open No. 2009-189941

[0007] When producing a laminate including two or more layers, it is desirable that the thickness of the layers formed is uniform. In the above-mentioned Patent Document 1, the apparatus for producing the laminate is complicated, and in the method of Patent Document 2, the uniformity of the thickness of the layers formed is insufficient.

[0008] Therefore, an object of the present invention is to provide a method for producing a laminate by forming a layer of uniform thickness on a base layer in a simple manner.

[0009] The present invention achieves the above-mentioned object as follows: [1] A method for producing a ceramic porous laminate by forming a ceramic porous layer on the inner surface of a ceramic porous body having one or more tubes, the method comprising: a slurry liquid supplying step (1) of supplying a slurry liquid containing inorganic particles to the inside of the tube; and a coating layer forming step (2) of passing a jig through the tube while or after the slurry liquid is being supplied to form a coating layer of the slurry liquid on the inner surface of the tube. [2] The manufacturing method according to [1], in which, when the jig is projected in the direction of movement of the jig within the tube, at least a part of the outer periphery of the projection is curved. [3] The manufacturing method according to [1] or [2], in which the slurry liquid is supplied to the inside of the tube by injection, and the jig is passed through after the slurry liquid is injected. [4] The manufacturing method according to any one of [1] to [3], wherein the jig is moved within the pipe by flowing a fluid other than the slurry liquid from behind the jig in the direction of jig movement along the direction of jig movement and / or by sucking the slurry liquid from the direction of advancement of the jig. [5] The manufacturing method according to any one of [1] to [4], wherein the inner peripheral shape of the cross section perpendicular to the axial direction of the pipe is circular. [6] The manufacturing method according to any one of [1] to [5], wherein the viscosity of the slurry liquid is 2 Pa s or more. [7] The manufacturing method according to any one of [1] to [6], further comprising a drying step (3) and / or a heat treatment step (4) of the coating layer after the coating layer forming step (2). [8] The manufacturing method according to any one of [1] to [7], wherein the slurry liquid supplying step (1) and the coating layer forming step (2) constitute one cycle, and this cycle is performed multiple times, and the direction of movement of the jig relative to the substrate in at least one of the cycles from the second cycle onwards is opposite to the direction of movement of the jig relative to the substrate in the first cycle.[9] The ceramic porous laminate further includes an intermediate layer containing inorganic particles X between the ceramic porous body and the ceramic porous layer, and the method for producing the ceramic porous laminate further includes, before the slurry liquid supplying step (1), a slurry liquid X supplying step (1X) and a coating layer forming step (2X) described below, in which the intermediate layer containing inorganic particles X is formed, wherein the slurry liquid supplying step (1) is a slurry liquid supplying step (1Y) of supplying a slurry liquid Y containing inorganic particles Y to the inside of a pipe on which the intermediate layer has been formed, and the coating layer forming step (2Y) is a coating layer forming step (2Y) of passing a jig through the pipe on which the intermediate layer has been formed while supplying the slurry liquid Y or after supplying the slurry liquid Y, to form a coating layer of the slurry liquid Y on the inner surface of the pipe. Slurry liquid X supplying step (1X): A slurry liquid X containing inorganic particles X is supplied to the inside of a pipe of a ceramic porous body having one or more pipes. Coating layer forming step (2X): While supplying the slurry liquid X or after supplying the slurry liquid X, a jig is passed through the pipe to form a coating layer of the slurry liquid X on the inner surface of the pipe.

[0010] According to the present invention, a porous ceramic laminate can be formed by a simple method, in which a porous ceramic layer of uniform thickness is formed on a porous ceramic substrate.

[0011] FIG. 1 is a photograph substituted for a drawing, showing the method for measuring the thickness of a ceramic porous layer.

[0012] The method for producing a ceramic porous laminate of the present invention is a method for producing a ceramic porous laminate by forming a ceramic porous layer on the inner surface of a ceramic porous body (hereinafter sometimes referred to as a substrate) having one or more tubes, and includes a slurry liquid supply step (1) for supplying a slurry liquid containing inorganic particles to the inside of the tube, and a coating layer formation step (2) for passing a jig through the tube while supplying the slurry liquid or after supplying the slurry liquid to form a coating layer of the slurry liquid on the inner surface of the tube.

[0013] The outer peripheral shape of the substrate is not particularly limited, and the outer peripheral shape of the substrate in a cross section perpendicular to the axial direction may be a circle, an ellipse, a square, a rectangle, or the like. The substrate may have one or more tubes, i.e., the substrate may be tubular or monolithic. Furthermore, it is preferable that the shape of the tube in a cross section perpendicular to the axial direction is a circle.

[0014] The thickness (average value) of the substrate is preferably 400 to 8000 μm. When the substrate is monolithic, the thickness may be the average value of the closest distance between adjacent tubes in a plane perpendicular to the major axis. The axial length of the substrate is, for example, 50 to 5000 mm, preferably 500 to 3000 mm. When the substrate is tubular, the outer diameter of the substrate is, for example, 5 mm to 20 mm, and the inner diameter of the tube is, for example, 1 mm to 15 mm. When the substrate is monolithic, i.e., has two or more tubes, the outer diameter of the substrate is, for example, 5 mm to 100 mm, and the inner diameter of each tube is, for example, 0.1 mm to 10 mm.

[0015] The substrate preferably comprises an inorganic oxide, for example Li ２ O, BeO, B ２ O ３ , Na ２ O, MgO, Al ２ O ３ , SiO ２ , K. ２ O, CaO, ScO ２ , TiO ２ , V ２ O ５ , Cr ２ O ３ , ZnO, Ga ２ O ３ , GeO ２ , As ２ O ５ , Rb ２ O, SrO, Y ２ O ３ , ZrO ２ , Nb ２ O ５ , Ag ２ O, CdO, In ２ O ３ , SnO ２ , Sb ２O ５ , TeO ２ , Cs ２ O, BaO, La ２ O ３ , Ta ２ O ５ , W.O. ３ , HgO, Tl ２ O, PbO, PbO ２ , and ThO ２ It is more preferable that the substrate contains at least one metal oxide selected from the group consisting of Al. ２ O ３ And, Al ２ O ３ It is more preferable that the base material contains one or more metal oxides other than Al. ２ O ３ The one or more metal oxides other than the above can be arbitrarily selected from the metal oxides exemplified above, and the substrate is Al ２ O ３ and SiO ２ It is particularly preferable that the glass contains such a material, and for example, an alumina substrate manufactured by Nippon Tokushu Ceramics Co., Ltd. In this specification, the term "metal" is used to include semimetals such as Si.

[0016] The pore diameter of the substrate measured by mercury intrusion porosimetry is preferably 0.1 μm or more, more preferably 1 μm or more, even more preferably 5 μm or more, and is preferably 20 μm or less, more preferably 18 μm or less, and even more preferably 15 μm or less. That is, the pore diameter is preferably 0.1 to 20 μm, more preferably 1 to 18 μm, and even more preferably 5 to 15 μm. The pore diameter means the diameter equivalent to 50% of the cumulative total in a graph with the pore diameter on the horizontal axis and the log differential pore volume on the vertical axis.

[0017] One or more intermediate layers may be formed on the inner surface of the substrate, and the present invention also includes forming a ceramic porous layer on the inner surface of the substrate via one or more intermediate layers.

[0018] The slurry liquid containing inorganic particles is a raw material for the ceramic porous layer formed on the substrate, and preferably contains a dispersant, a thickener and a solvent in addition to the inorganic particles.

[0019] The inorganic particles are preferably inorganic oxides. In a preferred embodiment, the above-mentioned examples of metal oxides contained in the base material can be referred to. In particular, the inorganic particles are Al ２ O ３ It is preferable that Al ２ O ３ As the inorganic particle, commercially available α-alumina can be used without any particular limitation, and examples thereof include AKP-3000, AKP-20, AA-10, and AA-5 manufactured by Sumitomo Chemical Co., Ltd. The volume-based cumulative 50% equivalent diameter of the inorganic particles is, for example, about 0.1 to 20 μm. The concentration of the inorganic particles in the slurry is, for example, 1 to 35 mass %.

[0020] The coating amount of inorganic particles was 0.1 g / cm ２ or less, and may be 0.005 g / cm ２ It is preferable that the density is 0.006 g / cm or more. ２ More preferably, it is 0.0071 g / cm or more. ２ That is, the coating amount of the inorganic particles is preferably 0.005 to 0.1 g / cm. ２ is preferably 0.006 to 0.1 g / cm ２ More preferably, it is 0.0071 to 0.1 g / cm ２ It is more preferable that:

[0021] The dispersant can suppress aggregation of inorganic particles in the slurry. The dispersant may be any of a cationic surfactant, an anionic surfactant, a nonionic surfactant, and an amphoteric surfactant. Among these, anionic surfactants such as ammonium polycarboxylates and amine polycarboxylates are preferred. Examples of suitable dispersant include SN Dispersant 5020, SN Dispersant 5023, SN Dispersant 5027, SN Dispersant 5468, Noparfa D-6010, Nopcol 5200, Nopcosant RFA, Nopcosperse 6100, and Nopcosperse 6150 manufactured by San Nopco Ltd. The concentration of the dispersant in the slurry (in terms of active ingredient) is, for example, 0.01% by mass or more and 10% by mass or less (0.01 to 10% by mass), and preferably 0.1% by mass or more and 8% by mass or less (0.1 to 8% by mass), relative to 100% by mass of the inorganic particles in the slurry.

[0022] Examples of thickeners include methyl cellulose, hydroxyethyl methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, polyalkylene oxide, polyvinyl alcohol, sodium polyacrylate, polyvinylpyrrolidone, polyacrylamide, polydimethylaminoethyl methacrylate, etc., with hydroxypropyl methyl cellulose being particularly preferred. The amount of thickener added can be adjusted appropriately depending on the target slurry viscosity.

[0023] The solvent may be water or an organic solvent.

[0024] After the inorganic particles are mixed with the dispersant, thickener, and solvent, which are preferably used, it is also preferable to carry out a degassing treatment.

[0025] It is also preferable to adjust the viscosity of the slurry liquid, and the viscosity of the slurry liquid is, for example, 2 Pa·s or more. The viscosity of the slurry liquid is preferably 4 Pa·s or more, more preferably 6 Pa·s or more, and is preferably 45 Pa·s or less, more preferably 40 Pa·s or less, even more preferably 38 Pa·s or less, and even more preferably 35 Pa·s or less. In other words, the viscosity of the slurry liquid is preferably 2 to 45 Pa·s, more preferably 4 to 40 Pa·s, even more preferably 6 to 38 Pa·s, and even more preferably 6 to 35 Pa·s. By setting the viscosity within such a range, the thickness of the laminated ceramic porous layer can be made uniform, and clogging of the tubes in the substrate can be avoided.

[0026] When supplying the slurry liquid to the substrate and when passing the jig through the pipe, it is preferable to arrange the substrate so that the axial direction thereof is vertical.

[0027] In the slurry liquid supply step (1), the slurry liquid may be supplied from either end of the substrate, but when the substrate is arranged so that its axial direction is vertical, it is preferable to supply the slurry liquid from the lower end of the substrate. The supply of the slurry liquid may be carried out by injecting the slurry liquid from the end of the substrate, or by masking the end face of the substrate other than the hole of the pipe and the side face of the substrate and immersing it in the slurry liquid, but it is preferable to supply the slurry liquid by injection from the end of the substrate (particularly one end).

[0028] In the coating layer forming step (2) of the slurry liquid, by using a jig, the excess slurry liquid supplied to the inner surface of the tube of the substrate can be discharged, and the slurry liquid can be uniformly applied to the inner surface of the tube of the substrate. The jig may be passed through the tube after the slurry liquid has been supplied, or may be passed through the tube while the slurry liquid is being supplied. It is preferable to supply the slurry liquid to the inside of the tube and then pass the jig after the supply of the slurry liquid, and it is more preferable to supply the slurry liquid to the inside of the tube by injection and then pass the jig after the injection of the slurry liquid.

[0029] The direction of supply of the slurry liquid and the direction of passing the jig may be the same or different. When the substrate is arranged so that its axial direction is vertical, it is preferable to pass the jig from the upper end after the slurry liquid has been supplied from the end of the substrate to the inner surface of the tube of the substrate.

[0030] Methods for passing the jig through the tube of the substrate include (i) flowing a fluid other than the slurry liquid from behind the jig in the direction of jig movement, (ii) sucking the slurry liquid from the direction of travel of the jig, or (iii) performing both of these. Furthermore, when the axial direction of the substrate is vertical, (iv) the jig may be passed through by dropping it from the upper end of the substrate under its own weight. Examples of the fluid include gases such as air. The methods of moving the jig are particularly preferred (i) to (iii), with (i) being more preferred. In the embodiment (i), when a fluid other than the slurry liquid is passed through, the pressure of the fluid may be, for example, 0.01 MPa to 0.5 MPa.

[0031] After the jig is passed through the tube of the substrate, the tube may be pressurized by flowing a fluid such as air through it for a certain period of time, or may not be held in that state. By holding the tube in a pressurized state for a certain period of time, the solvent, thickener, etc. in the slurry can be discharged to the outside of the tube through the pores of the substrate. The applied pressure is, for example, 0.01 MPa to 0.5 MPa, and the holding time is, for example, 0.01 to 30 minutes.

[0032] The material of the jig is not particularly limited, and jigs made of resin, metal, or ceramic can be used. The shape of the jig, when projected in the direction of jig movement inside the pipe, preferably has at least a portion of the outer periphery of the projection curved. Specific examples include coil, cylindrical, elliptical cylindrical, conical, spherical, and combinations thereof. Shapes obtained by cutting shapes other than the coil shape along one or more planes parallel to the direction of jig movement, removing a portion of the outer periphery while leaving a portion, are also preferred. The jig may be moved inside the pipe while rotating. The shape of the jig is preferably such that the inner periphery of the cross section perpendicular to the axial direction of the pipe is circular. Specifically, it is a cylinder or a sphere, with a sphere being more preferred. The size of the jig may be adjusted appropriately depending on the thickness of the ceramic porous layer to be formed, as long as it can be inserted inside the pipe.

[0033] After forming a coating layer of the slurry liquid on the inner surface of the pipe using the jig, it is preferable to carry out at least one of a drying step (3) for drying the coating and a heat treatment step (4).

[0034] Drying is preferably carried out at a temperature of 100° C. or less, and the coating layer is preferably air-dried. The temperature of the air blown onto the coating may be room temperature or may be warm air in the range of 100° C. or less. The speed of the air blown onto the coating surface is, for example, 0.05 to 1 m / sec.

[0035] Furthermore, the heat treatment step (4) can promote sintering of the inorganic particles contained in the slurry liquid, improve the strength of the layer formed from the slurry liquid, and appropriately adjust the porosity. The heat treatment step (4) may be performed after the coating layer formation step (2) without going through the drying step (3), but is preferably performed after the drying step (3). For example, it is preferably performed at a temperature above 100°C to 1500°C, preferably 300 to 1500°C, more preferably 500 to 1500°C, and even more preferably 1000 to 1500°C. The heat treatment time is, for example, 30 minutes to 10 hours, preferably 1 to 5 hours.

[0036] The thickness of the ceramic porous layer formed on the tube inner surface of the substrate may be adjusted by, for example, adjusting the viscosity of the slurry liquid, performing a series of steps including the slurry liquid supply step (1) and the slurry liquid coating layer formation step (2) (and, if necessary, the drying step (3) and / or the heat treatment step (4)) two or more times, adjusting the concentration of inorganic particles in the slurry, or adjusting the size of the jig. As described above, when the series of steps including (1) and (2) for forming the ceramic porous layer are performed two or more times, it is preferable that the direction of movement of the jig relative to the substrate in at least one of the second and subsequent steps is opposite to the direction of movement of the jig relative to the substrate in the first step.

[0037] Furthermore, in the present invention, when a ceramic porous laminate is produced in which a ceramic porous layer is formed on the tube inner surface of a substrate via one or more intermediate layers, it is preferable that the intermediate layer is also a ceramic porous layer containing inorganic particles, and it is more preferable that the intermediate layer is formed by the production method of the present invention. That is, it is preferable to perform a slurry liquid X supplying step (1X) in which a slurry liquid X containing inorganic particles X is supplied to the inside of a ceramic porous body having one or more tubes, and a coating layer forming step (2X) of the slurry liquid X to form an intermediate layer on the tube inner surface, and then perform a slurry liquid Y supplying step (1Y) in which a slurry liquid Y containing inorganic particles Y is supplied to the inside of the tube on which the intermediate layer has been formed, and a coating layer forming step (2Y) of the slurry liquid Y. After the coating layer forming step (2X), a drying step (3X) and / or a heat treatment step (4X) may be further performed, or a heat treatment step (4X) may be further performed after the drying step (3X). Furthermore, the drying step (3Y) and / or the heat treatment step (4Y) may be performed after the coating layer formation step (2Y), or the heat treatment step (4Y) may be performed after the drying step (3Y). Note that steps (1X) and (1Y) are the same as step (1) above except that the name of the slurry liquid is specified, and the entire description of step (1) can be referenced. Steps (2X) and (2Y) are the same as step (2) above except that the name of the slurry liquid is specified, and the entire description of step (2) can be referenced. Also, steps (3X) and (3Y), and steps (4X) and (4Y), can be referenced in their entirety to the descriptions of steps (3) and (4), respectively.

[0038] The inorganic particles X contained in the slurry liquid X and the inorganic particles Y contained in the slurry liquid Y are preferably the inorganic oxides exemplified above as preferred embodiments of the substrate, and both are Al ２ O ３ Preferably, the inorganic particles X include inorganic particles X1, and the inorganic particles Y include inorganic particles Y1 having a smaller average particle size than the inorganic particles X1. In this case, the inorganic particles X may include inorganic particles X2 having a smaller average particle size than the inorganic particles X1, together with the inorganic particles X1. The inorganic particles X2 and the inorganic particles Y1 may be the same or different. The inorganic particles X1, X2, and Y1 are all Al. ２ O ３ It is preferable that the above formula be used. By doing so (particularly, inorganic particles X include inorganic particles X1, inorganic particles Y include inorganic particles Y1, and inorganic particles X2 are included together with inorganic particles X1 as needed), even when the pore diameter of the substrate is relatively large, a ceramic porous layer can be uniformly formed on the substrate, and the strength of the interface between the substrate and the ceramic porous layer can also be improved. The volume-based cumulative 50% equivalent diameter of inorganic particles X1 is preferably 1 to 20 μm, the volume-based cumulative 50% equivalent diameter of inorganic particles Y1 is preferably 0.05 μm or more and less than 1 μm, and the volume-based cumulative 50% equivalent diameter of inorganic particles X2 is preferably 0.05 μm or more and less than 1 μm. It is particularly preferable that the pore diameter of the substrate measured by mercury porosimetry is 5 to 20 μm, the volume-based cumulative 50% equivalent diameter of inorganic particles X1 is 1 to 20 μm, and the volume-based cumulative 50% equivalent diameter of inorganic particles Y1 is 0.05 μm or more and less than 1 μm.

[0039] Furthermore, even when the intermediate layer described above is formed by the manufacturing method of the present invention, it is preferable to adjust the thickness of the ceramic porous layer by performing a series of steps including the slurry liquid Y supply step (1Y) and the slurry liquid Y coating layer formation step (2Y) (and, if necessary, the drying step (3Y) and the heat treatment step (4Y)) two or more times, and it is more preferable to reverse the direction of movement of the jig relative to the substrate in at least one of the second and subsequent steps in the ceramic porous layer formation step to the direction of movement of the jig relative to the substrate in the first step in the ceramic porous layer formation step. Furthermore, it is also possible to form two or more intermediate layers or increase the thickness of the intermediate layer by performing a series of steps including (1X) and (2X) (and, if necessary, (3X) and / or (4X)) two or more times.

[0040] The ceramic porous laminate obtained by the present invention has a ceramic porous body having one or more tubes, and a ceramic porous layer is formed on the tube inner surface with or without an intermediate layer. The thickness of the intermediate layer is, for example, 3 to 60 μm on average. The ceramic porous layer formed by the present invention has, for example, an average thickness of 5 to 100 μm, more preferably 20 to 80 μm. According to the present invention, it is possible to suppress the variation in thickness of the ceramic porous layer formed on the tube inner surface of the substrate, particularly the variation in thickness at both ends of the tube in the axial direction. The difference in film thickness of the ceramic porous layer formed on the tube inner surface of the substrate at both ends of the tube in the axial direction (the difference in the average value at each end) can be, for example, 16 μm or less, preferably 13 μm or less, more preferably 10 μm or less, with the lower limit being most preferably 0 μm, but may be around 1 μm. That is, the difference in film thickness at both ends of the tube in the axial direction is, for example, 0 to 16 μm, preferably 1 to 13 μm, and more preferably 1 to 10 μm.

[0041] The ceramic porous laminate obtained by the present invention can be used as a microfiltration membrane, an ultrafiltration membrane, or a nanofiltration membrane, and if necessary, can be further laminated with a functional layer to be used as a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, a reverse osmosis membrane, an ion exchange membrane, a separation membrane for gases, etc.

[0042] Examples of the functional layer include zeolite, MOFs (Metal Organic Frameworks), porous silica membranes, and porous alumina membranes. A separation membrane equipped with a functional layer can be produced by applying a liquid containing inorganic particles or MOFs that constitute the functional layer to the surface of the ceramic porous laminate obtained by the present invention and allowing the reaction to occur. The synthesis conditions can be appropriately selected depending on the functional layer to be laminated, but for example, a temperature of 80 to 800°C for 1 to 72 hours may be sufficient.

[0043] This application claims the benefit of priority based on Japanese Patent Application No. 2023-127031, filed on August 3, 2023. The entire contents of the specification of Japanese Patent Application No. 2023-127031, filed on August 3, 2023, are incorporated herein by reference.

[0044] The present invention will be described in more detail below with reference to examples. The present invention is not limited to the following examples, and can of course be practiced with appropriate modifications within the scope of the above and below-described aims, all of which are included in the technical scope of the present invention.

[0045] [Method for measuring pore diameter] The pore diameter D50 of the substrate was measured by mercury intrusion porosimetry using an Autopore V9620 (manufactured by Micromeritics) after drying the substrate at 120°C for 4 hours. By mercury intrusion porosimetry, a graph was obtained with the pore diameter on the horizontal axis and the cumulative log differential pore volume on the vertical axis, and the cumulative 50% equivalent diameter was obtained. The details of the measurement conditions are as follows. Adv. Contact Angle: 140.0° Rec. Contact Angle: 140.0° Mercury Temperature: 21°C Sample Mass: 1.0g Assembly Mass: 1.0g Penetrometer Volume: 1.0mL Penetrometer Mass: 1.0g Report Range: 1.07 to 59,256.30 psia

[0046] [Method for measuring particle size of metal oxide] The particle size distribution of the alumina used in the examples and comparative examples was measured using a laser diffraction / scattering particle size distribution measuring device (Microtrac MT3300EX II, manufactured by Microtrac Co., Ltd., 0.2 mass % aqueous solution of sodium hexametaphosphate), and the volume-based cumulative 50% equivalent diameter was measured.

[0047] [Method for measuring viscosity of slurry liquid] The viscosity of the slurries used in the examples and comparative examples was measured after the temperature of the slurry was brought to room temperature using a B-type viscometer (manufactured by Toki Sangyo Co., Ltd., Model BL) at room temperature, with the stirring speed measured in accordance with the manual for the instrument.

[0048] [Method for Measuring Ceramic Porous Layer Thickness] Cylindrical porous ceramic laminates obtained in the following Examples and Comparative Examples were cut perpendicular to the axial direction, with 3-4 cm sections from each end. The laminates were embedded in resin and mechanically polished so that the cut surfaces could be observed. Platinum was vapor-deposited on the polished surfaces, and the laminates were observed and photographed at 500x magnification using an FE-SEM (JEOL, JSM-7500FA). An angle (0°) of the cylindrical shape was arbitrarily determined, and angles from 0° to 90°, 180°, and 270° were set. From the obtained images, the thickness of a layer (porous ceramic layer) containing alumina powder X (described below) with a volume-based cumulative 50% equivalent diameter of approximately 0.5 μm, formed on a layer (intermediate layer) containing AA-10 particles, was measured at the four positions mentioned above. At each of the positions of 0°, 90°, 180°, and 270°, the distance from the outermost layer of the laminate to the layer adjacent to the outermost layer was measured at four arbitrary points. More specifically, as shown in Figure 1, four AA-10 particles located on the outermost side of the layer adjacent to the outermost layer were arbitrarily selected, and the distances from the surfaces of the AA-10 particles to the outermost layer were measured. The average values ​​of these distances were taken as the thicknesses at the positions of 0 degree, 90 degree, 180 degree, and 270 degree.

[0049] Example 1 (Substrate) Alumina and SiO ２ An alumina substrate A-13 (cylindrical shape with a pore diameter of 11 μm, an inner diameter of 7.0 mm, an outer diameter of 9.5 mm, and a length of 30 cm) manufactured by Nippon Special Ceramics Co., Ltd. containing the above was used.

[0050] (Formation of Intermediate Layer) In this example, the intermediate layer was also formed by the manufacturing method of the present invention. First, alumina powder AA-10 (volume-based cumulative 50% equivalent diameter: approximately 14 μm) manufactured by Sumitomo Chemical Co., Ltd., hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 as a dispersant were mixed with water at concentrations of 13.0 mass%, 1.9 mass%, and 1.3 mass%, respectively, and the mixture was degassed to prepare a slurry for the intermediate layer (hereinafter, referred to as slurry S1).

[0051] Next, the slurry S1 was filled into a catheter syringe manufactured by Terumo Corporation, and the syringe was placed upright with the outlet facing downward and left to stand for 1 hour. A tube was attached to the tip of the catheter syringe manufactured by Terumo Corporation, and one end of the substrate was placed vertically with the end facing downward (hereinafter referred to as end A; the other end opposite end A is referred to as end B). The tip of the tube was connected to this end, and the slurry S1 was injected around the entire inner circumference of the substrate. After injecting the slurry S1, a resin ball with a diameter of 6.35 mm was set at end B (upper end) of the substrate, and air was blown from end B at an air pressure of 0.1 MPa to move the ball from end B to end A, thereby discharging the slurry S1. After discharging the slurry S1, the ball was held at end A and maintained at 0.1 MPa for 600 seconds. After 600 seconds, the substrate was dried by rotating it at 6.9 rpm and blowing hot air at about 0.1 m / s across the inner surface of the substrate, thereby forming an intermediate layer containing AA-10 particles on the inner surface of the substrate.

[0052] (Preparation of Slurry for Ceramic Porous Layer) Commercially available alumina powder X (having a cumulative 50% equivalent diameter on a volume basis of approximately 0.5 μm), hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 (active ingredient 41%) as a dispersant were mixed with water at concentrations of 9.0 mass %, 1.0 mass %, and 0.9 mass %, respectively, and the mixture was degassed to prepare a slurry for a ceramic porous layer (hereinafter, slurry S2).

[0053] (Formation of ceramic porous layer 1) The slurry S2 was filled into a catheter syringe manufactured by Terumo Corporation, and the syringe was left standing with the outlet facing downward for 1 hour. A tube was attached to the tip of the catheter syringe manufactured by Terumo Corporation, and the end A of the substrate was placed vertically, with a layer (intermediate layer) containing AA-10 particles formed on the inner surface thereof, with the end A facing downward. The tip of the tube was connected to end A, and the slurry was injected into the entire inner circle of the substrate. After the slurry injection, a resin ball having a diameter of 6.0 mm was set at end B (upper end side) of the substrate, and air was blown from end B at an air pressure of 0.02 MPa to move the ball from end B to end A, thereby discharging the slurry. The substrate was rotated at 6.9 rpm, and hot air of about 0.1 m / s was blown across the inner surface of the substrate to dry it, and a ceramic porous layer containing the alumina powder X was formed on the layer (intermediate layer) containing AA-10 particles. The substrate having the layer containing AA10 particles (intermediate layer) and the ceramic porous layer containing alumina powder X formed on the inner peripheral surface thereof was heat treated at 1200° C. for 3 hours.

[0054] (Formation of ceramic porous layer 2) After the heat treatment, the slurry S2 was poured into the substrate with end B facing downward, a ball was set at end A (upper end) of the substrate, and air was allowed to flow from end A. The same procedure as in "Formation of ceramic porous layer 1" was repeated to obtain a porous ceramic laminate.

[0055] Example 2 A porous ceramic laminate of Example 2 was obtained in the same manner as in Example 1, except that the composition of the slurry S2 was changed to a slurry containing alumina powder X, hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 as a dispersant at concentrations of 9.0 mass%, 1.3 mass%, and 0.9 mass%, respectively.

[0056] Example 3 A porous ceramic laminate of Example 3 was obtained in the same manner as in Example 1, except that the composition of the slurry S2 was changed to a slurry containing alumina powder X, hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 as a dispersant at concentrations of 9.0 mass%, 1.5 mass%, and 0.9 mass%, respectively.

[0057] Example 4 A porous ceramic laminate of Example 4 was obtained in the same manner as in Example 1, except that the composition of the slurry S2 was changed to a slurry containing alumina powder X, hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 as a dispersant at concentrations of 9.0 mass%, 1.8 mass%, and 0.9 mass%, respectively.

[0058] Example 5 A porous ceramic laminate of Example 5 was obtained in the same manner as in Example 1, except that the composition of the slurry S2 was changed to a slurry containing alumina powder X, hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 as a dispersant at concentrations of 9.0 mass%, 2.0 mass%, and 0.9 mass%, respectively.

[0059] Comparative Example 1 In the same manner as in Example 1, an intermediate layer was formed on the inner surface of an alumina substrate A-13 manufactured by Nippon Tokushu Ceramics Co., Ltd., and then, in the same manner as in Example 1, slurry S2 was injected into the inside of the substrate with the intermediate layer formed on its inner surface. After injecting slurry S2, the tip of a 50 ml catheter syringe manufactured by Terumo Corporation was inserted into end A of the substrate (substrate with an intermediate layer formed on its inner surface) placed vertically with end A facing downward, and the slurry was manually aspirated and discharged with the syringe. As a result, the slurry clogged the inside of the tube hole in the substrate, and a laminate could not be obtained.

[0060] Comparative Example 2 A porous ceramic laminate of Comparative Example 2 was obtained in the same manner as in Comparative Example 1, except that the composition of the slurry S2 was changed to a slurry containing alumina powder X, hydroxypropyl methylcellulose 65SH-30000 manufactured by Shin-Etsu Chemical Co., Ltd. as a thickener, and SN Dispersant 5468 as a dispersant at concentrations of 9.0 mass%, 1.3 mass%, and 0.9 mass%, respectively.

[0061] The results are shown in Table 1.

[0062]

Claims

1. A method for producing a ceramic porous laminate by forming a ceramic porous layer on the inner surface of a ceramic porous body having one or more tubes, comprising: a slurry liquid supplying step (1) for supplying a slurry liquid containing inorganic particles to the inside of the tube; and a coating layer forming step (2) for passing a jig through the tube to form a coating layer of the slurry liquid on the inner surface of the tube while supplying the slurry liquid or after supplying the slurry liquid.

2. The manufacturing method according to claim 1, wherein when said jig is projected in the direction of travel of the jig within said pipe, at least a portion of the outer periphery of the projection is curved.

3. The manufacturing method according to claim 2, wherein the slurry liquid is supplied to the inside of the pipe by injection, and the jig is passed through after the slurry liquid is injected.

4. A manufacturing method as described in claim 3, in which the jig is moved within the pipe by flowing a fluid other than the slurry liquid from behind the jig in the direction of movement of the jig, and / or by sucking the slurry liquid from the direction of travel of the jig.

5. The manufacturing method according to claim 3, wherein the inner circumferential shape of the cross section perpendicular to the axial direction of the tube is a circle.

6. The manufacturing method according to claim 3, wherein the viscosity of the slurry liquid is 2 Pa·s or more.

7. The method according to claim 1, further comprising a step of drying the coating layer (3) and / or a step of heat treating the coating layer (4) after the coating layer forming step (2).

8. The manufacturing method according to claim 1, in which the slurry liquid supplying step (1) and the coating layer forming step (2) constitute one cycle, and this cycle is repeated multiple times, and the direction of movement of the jig relative to the substrate in at least any cycle from the second cycle onwards is opposite to the direction of movement of the jig relative to the substrate in the first cycle.

9. The ceramic porous laminate has an intermediate layer containing inorganic particles X1 between the ceramic porous body and the ceramic porous layer, and the manufacturing method of the ceramic porous laminate further comprises, before the slurry liquid supplying step (1), the following slurry liquid X supplying step (1X) and coating layer forming step (2X) for forming an intermediate layer containing inorganic particles X1, wherein the slurry liquid supplying step (1) is a slurry liquid supplying step (1Y) of supplying a slurry liquid Y containing inorganic particles Y1 to the inside of the pipe on which the intermediate layer is formed, and the coating layer forming step (2) is a coating layer forming step (2Y) of passing a jig through the pipe on which the intermediate layer is formed while supplying the slurry liquid Y or after supplying the slurry liquid Y, to form a coating layer of the slurry liquid Y on the inner surface of the pipe. Slurry liquid X supplying step (1X): A slurry liquid X containing inorganic particles X1 is supplied to the inside of a tube of a ceramic porous body having one or more tubes. Coating layer forming step (2X): While supplying the slurry liquid X or after supplying the slurry liquid X, a jig is passed through the tube to form a coating layer of the slurry liquid X on the inner surface of the tube.

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