Method for manufacturing ceramic structures

Abstract

To provide a ceramic structure having excellent strength.SOLUTION: A ceramic structure has an outer peripheral part and a partition wall arranged in an approximately lattice-like pattern inside the peripheral part, and has a distribution of porosity in the same partition wall. As the distribution of porosity, it is preferred that: a maximum value of porosity is in a range of 60% and a minimum value thereof is 5%, and the difference between the maximum value and the minimum value thereof is 10% or more; the maximum value of porosity is in a range of 30% to 60% and the minimum value thereof is 5% to 30%; and the like.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a ceramic structure and a method for manufacturing the ceramic structure.

Background Art

[0002] For the purpose of obtaining a porous honeycomb filter having sufficient strength to withstand practical use and capable of combining a low pressure loss and a high collection rate, for example, a porous first partition wall that allows a fluid to pass through and a second partition wall that is less permeable to the fluid than the first partition wall are provided, and the first partition wall has a structure with a larger porosity than the second partition wall. A porous honeycomb filter has been proposed (see, for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, the ceramic structure described in Patent Document 1 has a problem that the portion with a high porosity and weak strength is easily broken.

[0004] An object of the present invention is to provide a ceramic structure having excellent strength.

Means for Solving the Problems

[0005] The ceramic structure of the present invention as means for solving the above problems has an outer peripheral portion and partition walls arranged substantially in a lattice shape inside the outer peripheral portion, and has a porosity distribution in the same partition wall.

Effects of the Invention

[0006] According to the present invention, an object is to provide a ceramic structure having excellent strength.

Brief Description of the Drawings

[0007] [Figure 1] FIG. 1 is a schematic perspective view showing an example of a filter which is a ceramic structure of the present invention. [Figure 2] Figure 2 shows an example of a cross-section of a partition wall in a ceramic structure. [Figure 3] Figure 3 shows another example of a partition wall cross-section of a ceramic structure. [Figure 4] Figure 4 is a flowchart showing an example of the processing flow in a method for manufacturing ceramic structures. [Figure 5] Figure 5 is a schematic diagram showing an example of a powder layer forming means in a ceramic structure manufacturing apparatus. [Figure 6] Figure 6 is a schematic diagram showing an example of a liquid supply means in a ceramic structure manufacturing apparatus. [Modes for carrying out the invention]

[0008] (Ceramic structure) The ceramic structure of the present invention has partitions arranged in a substantially grid pattern on the outer periphery and inside the outer periphery, and has a distribution of porosity within the same partition.

[0009] In the present invention, the ceramic structure has a mixture of portions with high porosity to enhance adsorption capacity and portions with relatively low porosity to enhance strength within the same partition wall, thereby achieving excellent strength.

[0010] In terms of porosity distribution, a range from a maximum of 60% to a minimum of 5%, with a difference of 10% or more between the maximum and minimum porosity values, is preferable because it enables the achievement of excellent strength. The difference between the maximum and minimum porosity is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. The maximum porosity is preferably in the range of 30% to 60%, and the minimum is preferably in the range of 5% to 30%.

[0011] In terms of the distribution of porosity within a single partition wall, it is preferable that the areas with high porosity are predominantly located inside the partition wall, while the areas with low porosity are predominantly located outside the partition wall, as this allows for the achievement of superior strength. Porosity can be calculated, for example, by observing a cross-section of a septum using a scanning electron microscope (SEM), binarizing the pores and particles, and then processing the image. The presence of a porosity distribution within the same septum can be confirmed, for example, by SEM observation.

[0012] The ceramic structure of the present invention is not particularly limited in terms of its material, shape, size, structure, etc., and can be appropriately selected according to the purpose.

[0013] There are no particular restrictions on the material of the ceramic structure, and it can be appropriately selected according to the purpose. Examples of ceramics include cordierite, SiC, aluminum titanate, ceria-zirconia solid solution, alumina, and mullite. There are no particular restrictions on the shape and size of the ceramic structure; they can be appropriately selected according to the purpose. There are no particular restrictions on the structure of the ceramic structure; it can be appropriately selected according to the purpose.

[0014] Ceramic structures possess excellent strength and can be used in various fields, but they are particularly suitable for use as filters to remove impurities by allowing fluids such as gases, liquids, powders, or mixtures of any combination thereof to pass through. The fluid is typically exhaust gas from an engine. Ceramic filters are preferably used to purify exhaust gas from engines such as gasoline and diesel engines, although this is not always the case.

[0015] Here, FIG. 1 is a schematic perspective view showing an example of a filter which is a ceramic structure of the present invention. The filter of FIG. 1 includes a filter main body 1, an outer peripheral portion 2 of the filter, and a partition wall 3. The shape of the filter does not have to be a cylindrical shape as shown in FIG. 1, and may be a square or an elliptical shape or the like. Further, the partition wall 3 does not have to be arranged in a lattice shape as shown in FIG. 1, and may be a radial or curved partition wall.

[0016] FIGS. 2 and 3 are diagrams showing an example of a cross section of a partition wall of a ceramic structure, and may be a cross-sectional structure in any of the x-y plane, y-z plane, and x-z plane. The partition wall has different porosity distributions, and a dense portion (a portion with a small porosity) 4 and a sparse portion (a portion with a large porosity) are mixed, and there is no particular limitation on the dense and sparse arrangement. Further, it may have a plurality of porosity distributions.

[0017] (Method for manufacturing a ceramic structure) The method for manufacturing a ceramic structure of the present invention is a method for manufacturing a ceramic structure of the present invention, and includes a powder layer forming step, a liquid applying step, and a maintaining step, and further includes other steps as necessary.

[0018] In the present invention, "the method for manufacturing a ceramic structure" includes steps until a green body before a debinding step is produced. The "green body" indicates, in the present invention, an object composed of a ceramic, a binder resin, and a solvent, which is formed by repeating the powder layer forming step and the liquid applying step. The "ceramic structure" indicates, in the present invention, a member in which all steps are mainly completed, and thus indicates a state in which debinding and sintering are completed.

[0019] <Powder layer forming step> The powder layer forming step is a step of forming a powder layer with primary particles containing a ceramic material and secondary particles containing a binder resin, and is carried out by powder layer forming means.

[0020] Examples of the ceramic material include glass, metal oxides, metal carbides, metal nitrides, and the like.

[0021] Examples of glass include silica glass (quartz glass) and soda-lime silica glass. Examples of metal oxides include zirconia, alumina, and mullite (aluminosilicate minerals). Examples of metal carbides include silicon carbide and tungsten carbide. Examples of metal nitrides include silicon nitride and aluminum nitride. Ceramics may be used individually or in combination of two or more types. Among these, zirconia, alumina, mullite (aluminosilicate mineral), tungsten carbide, silicon carbide, silicon nitride, and aluminum nitride are preferred from the viewpoint of maintaining high strength.

[0022] The binding resin contained in the secondary particles contributes, for example, to the binding between primary particles, and to re-binding surrounding ceramic particles after dissolving during liquid dropping. There are no particular restrictions on the type of binder resin, and it can be appropriately selected according to the purpose. Examples include acrylic resin, maleic acid resin, silicone resin, butyral resin, polyester resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyethylene resin, polypropylene resin, polyacetal resin, polyvinyl butyral resin, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, α-olefin-maleic anhydride copolymer, esterified α-olefin-maleic anhydride copolymer, polystyrene, poly(meth)acrylic acid ester, α-olefin-maleic anhydride-vinyl group-containing monomer copolymer, styrene-maleic anhydride copolymer, styrene-(meth)acrylic acid ester copolymer, polyamide resin, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or its derivatives, coumarone indene resin, terpene resin, polyurethane resin, styrene-butadiene rubber, nitrile rubber, acrylic rubber, ethylene-propylene rubber, and nitrocellulose. These may be used individually or in combination of two or more.

[0023] There are no particular limitations on the method for forming the powder layer, and it can be appropriately selected depending on the purpose. Examples include a method using a known counter rotation mechanism (counter roller) used in the selective laser sintering method described in Japanese Patent Publication No. 3607300, a method of spreading the powder into a thin layer using components such as brushes, rollers, and blades, a method of spreading the powder into a thin layer by pressing the surface of the powder with a pressing member, and a method using a known powder additive manufacturing apparatus.

[0024] When forming a powder layer on a support using a counter-rotating mechanism (counter roller), brush or blade, pressing member, etc., for example, the powder layer is formed by placing the secondary particles on a support that is positioned to move up and down while sliding along the inner wall of an outer frame (sometimes referred to as a "mold," "hollow cylinder," or "cylindrical structure") within the outer frame, using a counter-rotating mechanism, brush, brush or blade, pressing member, etc. In this case, if a support that can move up and down within the outer frame is used, it is preferable to position the support slightly below the upper end opening of the outer frame (by the thickness of the powder layer) and place the powder on the support.

[0025] Furthermore, the powder layer can be formed automatically and easily using a known powder bed fusion apparatus. A powder bed fusion apparatus generally comprises a recoater for stacking secondary particles, a movable supply tank for supplying secondary particles onto a support, and a movable molding tank for forming and stacking layers of secondary particles. In this powder bed fusion apparatus, the surface of the supply tank can be raised slightly above the surface of the molding tank by raising the supply tank, lowering the molding tank, or both. Therefore, this powder bed fusion apparatus can form a powder layer by stacking secondary particles using the recoater from the supply tank side, and the powder layer can be stacked by repeatedly moving the recoater.

[0026] There are no particular restrictions on the average thickness of the powder layer, and it can be appropriately selected depending on the purpose. However, the average thickness per layer is preferably 10 μm to 200 μm, and more preferably 30 μm to 100 μm.

[0027] <Liquid application process> The liquid application step is a process of applying a liquid that dissolves the binder resin to the powder layer, and is carried out by a liquid application means.

[0028] -liquid- As for the liquid, there are no particular restrictions as long as it can dissolve the binder resin of the secondary particles, and it can be appropriately selected according to the purpose. The liquid preferably contains a solvent and inorganic particles, and may further contain other components as needed.

[0029] There are no particular restrictions on the solvent, and it can be appropriately selected depending on the purpose. Examples include water, alcohols with 2 to 7 carbon atoms, ketones with 3 to 8 carbon atoms, cyclic ethers, polyethers, and ester compounds. These may be used individually or in combination of two or more.

[0030] Examples of alcohols with 2 to 7 carbon atoms include ethyl alcohol, isopropanol, and n-butanol. Examples of ketones having 3 to 8 carbon atoms include acetone, ethyl methyl ketone, and diacetone alcohol. Examples of cyclic ethers include tetrahydrofuran. Examples of polyethers include dimethoxyethanol and dimethoxydiethylene glycol. Examples of ester compounds include methyl acetate, ethyl acetate, and butyl acetate.

[0031] There are no particular restrictions on the solvent content in the liquid, and it can be appropriately selected depending on the purpose, but 35% by mass or more and 99% by mass or less is preferred, and 35% by mass or more and 75% by mass or less is more preferred. A low water content in the liquid is preferable. The water content in the liquid is preferably less than 45% by mass, and preferably less than 5% by mass.

[0032] -Inorganic particles- The liquid preferably contains inorganic particles with a medium particle size that does not clog the nozzle. When the liquid contains inorganic particles, the inorganic particles are positioned in the gaps between the powder particles in a given area when the liquid is applied to that area. As a result, the density of the resulting three-dimensional object is improved.

[0033] The material of the inorganic particles is preferably the same as the material of the ceramic material, and more preferably zirconia, alumina, mullite (aluminosilicate mineral), tungsten carbide, silicon carbide, silicon nitride, or aluminum nitride. There are no particular restrictions on the inorganic particle content, and it can be appropriately selected depending on the purpose, but it is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to the total volume of the liquid. The upper limit of the inorganic particle content is preferably 75% by mass or less, and more preferably 65% ​​by mass or less.

[0034] -Other ingredients- Other ingredients are not particularly limited and can be selected as appropriate depending on the purpose, such as dispersants and surfactants.

[0035] In the liquid application process, the binder resin contained in the secondary particles is dissolved, converting them into primary particles. The primary particles then fill the voids formed between the secondary particles. As a result, the liquid-applied area is fixed by the binder resin, and the deformation of the secondary particles homogenizes the liquid-applied area, reducing voids and unsolidified areas. Furthermore, the edges of the liquid-applied area can have planar irregularities caused by the secondary particles reduced, enabling highly accurate molding.

[0036] The liquid application process is not particularly limited as long as it involves applying a liquid that dissolves the binder resin contained in the secondary particles to a predetermined area, and can be appropriately selected according to the purpose. Methods for applying liquid to a predetermined area include, for example, a dispenser method, a spray method, and an inkjet method. Among these methods, the dispenser method offers excellent droplet quantity control but has a limited coating area. The spray method allows for easy formation of fine particles, offers a wide coating area and excellent coating performance, but suffers from poor droplet quantity control and the scattering of secondary particles due to the spray flow. For this reason, the inkjet method is particularly preferred. Compared to the spray method, the inkjet method has the advantage of better droplet quantity control and a larger coating area compared to the dispenser method, and is preferred because it can form complex three-dimensional shapes accurately and efficiently. In the case of the inkjet method, the application means has a nozzle capable of applying liquid to a predetermined area by the inkjet method. A nozzle (discharge head) from a known inkjet printer can be suitably used as the nozzle, and an inkjet printer can also be suitably used as the application means. A suitable example of an inkjet printer is the Ricoh SG7100. Inkjet printers are preferable because they can dispense a large amount of liquid at once from the head and have a wide coating area, thus enabling high-speed coating.

[0037] <Maintenance process> The maintenance process involves maintaining the dispersion state of the solid components in the liquid used to dissolve the binder resin. This maintenance process allows for adjustment of the porosity of the ceramic structure. Examples of solid components in a liquid include inorganic particles and dispersants. Methods for maintaining the dispersion of solids in a liquid include, for example, mixing the liquid by making slight vibrations within the liquid chamber of the inkjet head, and flushing by ejecting old liquid to replace it with new liquid before applying new liquid. The maintenance process is not particularly limited and may be performed before the powder layer formation process, before the liquid application process, or at predetermined intervals.

[0038] <Other processes> Other processes are not particularly limited and can be selected as appropriate depending on the purpose, such as heat treatment processes. Heat treatment processes include drying, degreasing, and sintering. While heat treatment can be performed according to the material, the resulting green body generally has a distinctive shape, and therefore, pressurization is often not used to prevent its collapse. In particular, in sintering, pressurized sintering (hot pressing) is often performed to improve sintering density, but in this invention, this is not used, and atmospheric pressure sintering is basically assumed.

[0039] In this invention, a method for manufacturing a three-dimensional object that is a ceramic structure is used, in which the raw materials of the three-dimensional object are temporarily bonded together before the object is obtained. In this case, even if resin is used for bonding, for example, only a small amount of resin is needed, resulting in less volume shrinkage after sintering. As a result, cracking during sintering can be prevented even when fabricating large structural members, making it possible to fabricate models with dimensions that are practical for use as structural members.

[0040] The green body, formed by repeatedly going through the powder layer formation process and the liquid application process, is completed with the object embedded in the powder during the three-dimensional molding process. At that stage, the green material contains a large amount of solvent, resulting in low strength and poor handling properties, so drying is necessary. Drying can also be performed layer by layer using an infrared heater or the like after the powder layer formation process and the liquid application process. There are no particular restrictions on the drying method, and any known method can be used. However, it is necessary to select a method that does not cause cracking or deformation depending on the type of solvent. For example, if ethanol is used as the solvent, it is preferable to dry at 50°C for 24 hours.

[0041] There are no particular restrictions on the degreasing method, and any well-known method can be used. For example, when kaolin is used as the primary particle, degreasing can be suitably achieved by heat treatment at 500°C for 3 hours under a nitrogen-purged environment, but the method is not limited to this.

[0042] There are no particular restrictions on the sintering method, and well-known methods can be used, but in order to maximize the effects of the present invention, it is preferable to perform sintering under atmospheric pressure. The atmosphere, heat treatment temperature, and heat treatment time need to be adjusted depending on the material. For example, when alumina is used as the primary particle, heat treatment at 1,550°C for 3 hours under an argon atmosphere is preferable. Increasing the heat treatment temperature can increase the density, but this also has disadvantages such as a decrease in strength due to the formation of coarse particles and deformation, so optimization of the conditions is necessary. As for the sintering method, for example, in the case of graphite type, an electric current sintering method such as pulsed current heating can be suitably used, but it is not limited to this.

[0043] Here, Figure 4 is a flowchart showing an example of the processing flow in the manufacturing method of a ceramic structure. This manufacturing method of the ceramic structure is just one example, and other methods may also be used. The processing flow in the manufacturing method of the ceramic structure shown in Figure 4 will be explained below with reference to Figures 5 and 6.

[0044] In step S1, the user inputs the number of repetitions to the ceramic structure manufacturing apparatus, and the process then moves to S2.

[0045] In step S2, when the user inputs k=0 to the ceramic structure manufacturing apparatus, the process proceeds to S3.

[0046] In step S3, a maintenance process is performed to maintain the dispersion state of the solids in the liquid, and then the process moves to S4. The maintenance process is, for example, a process of vibrating the liquid near the nozzle or a flushing process.

[0047] In step S4, once the ceramic structure manufacturing apparatus has performed the powder layer formation process, the process proceeds to S5. In the powder layer formation process, a powder layer is formed with primary particles containing ceramic material and secondary particles containing a binder resin. The powder layer formation process can be carried out, for example, using a powder layer formation means. The powder layer forming means includes, for example, as shown in Figure 5, a supply-side powder storage tank 52 for storing particles 51, a molding-side powder storage tank 54 for forming the powder layer, and a leveling mechanism 55. The supply-side powder storage tank 52 has a vertically movable stage 50. The molding-side powder storage tank 54 has a vertically movable stage 53. As the roller, which acts as the leveling mechanism 55, moves from the supply-side powder storage tank 52 to the molding-side powder storage tank 54, the particles 51 in the supply-side powder storage tank 52 move to the molding-side powder storage tank 54, and a powder layer consisting of particles 51 is formed on the stage 53.

[0048] In step S5, once the ceramic structure manufacturing apparatus has performed the liquid application process, the process proceeds to S6. In the liquid application step, liquid is applied to the powder layer formed in the powder layer formation step. The liquid application step is performed using a liquid application means. As an example of a liquid application means, as shown in Figure 6, it is an inkjet head 57. The inkjet head 57 is used to apply liquid 58 to a predetermined area of ​​the powder layer 56.

[0049] In step S6, once the ceramic structure manufacturing apparatus has completed the heating process, the process proceeds to S7. In the heating process, the powder layer after the liquid application process is subjected to heat treatment. The heating process is carried out, for example, using a heating means. As a heating means, for example, an infrared heater is used to heat the molding powder.

[0050] In step S7, if we set k+1=k, we proceed to S8.

[0051] In step S8, if k is less than the number of iterations, the process moves to S3; if k is greater than or equal to the number of iterations, the process moves to S9. The maintenance process, powder layer formation process, liquid application process, and heating process are repeated until the desired number of layers is reached. In this way, a layered structure is obtained on stage 53. By drying this, a green body is obtained.

[0052] In step S9, the ceramic structure manufacturing apparatus completes the process by performing a heat treatment step. In the heat treatment step, the dried green body is heated. The heat treatment step is performed using, for example, a heat treatment means. Examples of heat treatment means include a heating device. In the heat treatment step, for example, the decomposition and removal of the resin and the sintering of the green body can be performed in one step. As a result, a ceramic structure is obtained in which the ceramic raw materials have been sintered. [Examples]

[0053] The following describes embodiments of the present invention, but the present invention is not limited in any way to these embodiments.

[0054] (Examples 1-5 and Comparative Examples 1-5) A ceramic structure (filter) as shown in Figure 1 was manufactured according to a flowchart illustrating an example of the processing flow in the manufacturing method of the ceramic structure shown in Figure 4.

[0055] The powder used was prepared using the materials shown in Table 1 below, as described below. <Preparation of primary and secondary particles> A slurry was prepared by mixing the ceramic material (high-purity alumina) shown in Table 1 with a binder resin (acrylic resin or PVB) in a solvent (ethanol) and thoroughly dispersing them. Next, the obtained slurry was granulated into droplets using a spray granulator and a drying sintering furnace, and then dried. Secondary particles were then obtained by classification as needed.

[0056] <Liquid for dissolving the binder resin> A solution was prepared by adding 100 parts by mass of ethyl acetate, 45 parts by mass of inorganic particles (alumina, Al2O3), and 5 parts by mass of SN Dispersant 5468 manufactured by Sunopco as a dispersant, and stirring for 24 hours.

[0057] <Sculpture> The fabrication was performed using a binder jet 3D printer (Shop system, manufactured by Desktopmetal), specifically a simplified prototype machine with some solvent-compatible modifications. The layer spacing was set to 100 μm. A cylindrical filter with partitions arranged in a roughly grid pattern on the outer perimeter and inside the outer perimeter, as shown in Figure 1, was fabricated. In Examples 1-5 and Comparative Examples 1-5, drawing data was created to achieve the porosity and porosity distribution shown in Tables 1 and 2, respectively, and the modeling was performed according to this drawing data. For example, the dispensing interval of the liquid dissolving the binder resin was shortened in areas with high density, and lengthened in areas with low density. In addition, the maintenance process shown in Table 1 was performed in Examples 1-5. The amount of liquid applied was set to 600 dpi.

[0058] <Degreasing and Sintering> Degreasing and sintering were performed using an electric furnace, with the temperature raised at 5°C / min to predetermined temperatures between 1,100°C and 1,500°C, held for 2 hours, and then cooled in the furnace. Filters for Examples 1-5 and Comparative Examples 1-5 were then fabricated.

[0059] Next, the characteristics of each obtained filter were evaluated as follows. The results are shown in Tables 1 and 2.

[0060] <Evaluation of porosity> The cross-sections of the partition walls of each obtained filter were observed using a scanning electron microscope (SEM, VE-8800, manufactured by Keyence Corporation). The pores and particles were binarized, and the area of ​​the pores and the area of ​​the particles were calculated using the image editing software ImageJ. The porosity (%) was then determined by calculating (area of ​​pores) / (area of ​​pores + area of ​​particles). Based on the porosity measurement results, we determined whether there was a different distribution of porosity within the septum, the porosity of the dense areas (areas with low porosity) and the sparse areas (areas with high porosity), and the difference between them.

[0061] <Strength Evaluation> The partition walls of each obtained filter were cut out, and their four-point bending strength was measured according to the method conforming to the Japanese Industrial Standard JIS R1601. Strength evaluation was then performed according to the following criteria. [Evaluation Criteria] ○: 4-point bending strength of 1.5 MPa or higher ×: 4-point bending strength is less than 1.5 MPa

[0062] <Pressure loss evaluation> Each of the obtained filters was subjected to a 5m vacuum test using a vacuum device (CV-TN96, manufactured by Hitachi, Ltd.). 3 Suction was performed at a rate of / min., and the rate of flow reduction when suction was passed through each filter was measured using a flow meter (mass flow meter for gases, manufactured by TSI). The rate of flow reduction (%) was calculated using the formula (Flow rate when passed through the filter / 5) × 100), and the pressure loss was evaluated according to the following criteria. [Evaluation Criteria] ○: Flow rate reduction rate is less than 10% ×: Flow rate reduction rate is 10% or more

[0063] <Overall Rating> A comprehensive evaluation was conducted based on the following criteria. [Evaluation Criteria] ○: When both the strength evaluation and the pressure loss evaluation are ○ ×: If at least one of the strength evaluation or pressure loss evaluation results in a ×

[0064] [Table 1]

[0065] -Maintenance process- *Micro-vibration: Mixing the liquid that dissolves the binder resin within the liquid chamber of the inkjet head. *Flushing: Discharge a liquid that dissolves the old binder resin and supply a liquid that dissolves the new binder resin.

[0066] -composition- *Ceramic material: AA series manufactured by Sumitomo Chemical Co., Ltd., high-purity alumina, median particle size (D 50 ) = 500nm *Acrylic resin: Acrylic polyol resin manufactured by Taisei Fine Chemical Co., Ltd. *PVB: Polyvinyl butyral resin, manufactured by Sekisui Chemical Co., Ltd., Esrec B

[0067] [Table 2]

[0068] Examples of the present invention are as follows: <1> This ceramic structure is characterized by having partition walls arranged in a substantially grid pattern on the outer periphery and inside the outer periphery, and having a distribution of porosity within the same partition wall. <2> The distribution of the porosity is such that the maximum value of the porosity is 60% and the minimum value is 5%, and the difference between the maximum and minimum values ​​of the porosity is 10% or more. <1> This is a ceramic structure as described in [reference]. <3> The maximum value of the porosity is in the range of 30% to 60%, and the minimum value of the porosity is in the range of 5% to 30%, <1> from <2> It is a ceramic structure as described in any of the following. <4> As for the distribution of porosity within the same partition wall, the portion with high porosity is largely distributed inside the partition wall, and the portion with low porosity is largely distributed outside the partition wall. <1> from <3> It is a ceramic structure as described in any of the following. <5> The filter, <1> from <4> It is a ceramic structure as described in any of the following. <6> The aforementioned <1> from <5> A method for manufacturing a ceramic structure as described in any of the following, A powder layer formation step in which a powder layer is formed with primary particles containing ceramic material and secondary particles containing a binder resin, A liquid application step in which a liquid that dissolves the binder resin is applied to the powder layer, A maintenance step to maintain the dispersion state of the solids in the liquid, This is a method for manufacturing a ceramic structure, characterized by containing [a specific substance]. <7> The binder resin is at least one selected from acrylic resin, maleic acid resin, silicone resin, butyral resin, polyester resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyethylene resin, polypropylene resin, polyacetal resin, polyvinyl butyral resin, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, α-olefin-maleic anhydride copolymer, esterified α-olefin-maleic anhydride copolymer, polystyrene, poly(meth)acrylic acid ester, α-olefin-maleic anhydride-vinyl group-containing monomer copolymer, styrene-maleic anhydride copolymer, styrene-(meth)acrylic acid ester copolymer, polyamide resin, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or its derivatives, coumarone indene resin, terpene resin, polyurethane resin, styrene-butadiene rubber, nitrile rubber, acrylic rubber, ethylene-propylene rubber, and nitrocellulose. <6> This is a method for manufacturing the ceramic structure described in [reference].

[0069] The aforementioned <1> from <5> A ceramic structure as described in any of the above, and the <6> from <7> According to the method for manufacturing ceramic structures described in any of the above, the conventional problems can be solved and the objectives of the present invention can be achieved. [Explanation of symbols]

[0070] 1. Filter body 2. Outer periphery 3 Bulkhead 4. Dense areas 5. Rough parts 10 filters 51 Secondary particles 52 Supply-side powder storage tank 53 stages 54 Powder storage tank on the molding side 55. Leveling mechanism (roller) 56 Powder layer 57 Inkjet heads 58 Liquid for dissolving the binder resin [Prior art documents] [Patent Documents]

[0071] [Patent Document 1] Patent No. 6729356

Claims

1. A method for manufacturing a ceramic structure having partitions arranged in a substantially grid pattern on the outer periphery and inside the outer periphery, and having a distribution of porosity within the same partition, A powder layer formation step in which a powder layer is formed with primary particles containing ceramic material and secondary particles containing a binder resin, A liquid application step in which a liquid that dissolves the binder resin is applied to the powder layer, A maintenance step to maintain the dispersion state of the solids in the liquid, A method for manufacturing a ceramic structure, characterized by containing [a certain substance].

2. A method for manufacturing a ceramic structure according to claim 1, comprising a heat treatment step of heat-treating the powder layer.

3. The method for manufacturing a ceramic structure according to Claim 2, wherein the distribution of porosity is such that the maximum value of the porosity is 60% and the minimum value is 5%, and the difference between the maximum and minimum values ​​of the porosity is 10% or more.

4. A method for manufacturing a ceramic structure according to any one of claims 2 to 3, wherein the maximum value of the porosity is in the range of 30% to 60%, and the minimum value of the porosity is in the range of 5% to 30%.

5. The method for manufacturing a ceramic structure according to any one of Claims 2 to 3, wherein the distribution of porosity within the same partition wall is such that the portion with high porosity is largely distributed inside the partition wall, and the portion with low porosity is largely distributed outside the partition wall.

6. The method for manufacturing a ceramic structure according to any one of claims 2 to 3, wherein the ceramic structure is a filter.

7. A method for producing a ceramic structure according to any one of claims 1 to 2, wherein the binder resin is at least one selected from acrylic resin, maleic acid resin, silicone resin, butyral resin, polyester resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate copolymer, polyethylene resin, polypropylene resin, polyacetal resin, polyvinyl butyral resin, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, α-olefin-maleic anhydride copolymer, esterified α-olefin-maleic anhydride copolymer, polystyrene, poly(meth)acrylic acid ester, α-olefin-maleic anhydride-vinyl group-containing monomer copolymer, styrene-maleic anhydride copolymer, styrene-(meth)acrylic acid ester copolymer, polyamide resin, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or its derivative, coumarone indene resin, terpene resin, polyurethane resin, styrene-butadiene rubber, nitrile rubber, acrylic rubber, ethylene-propylene rubber, and nitrocellulose.

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