Cleaning liquid, method for cleaning release mold, and method for producing ceramic formed body

Abstract

To provide a cleaning liquid excellent in cleanability of a release mold for producing a ceramic molded body, a method for cleaning a release mold, and a method for producing a ceramic molded body.SOLUTION: The cleaning solution of the present invention is a cleaning solution for a release mold for producing a ceramic molded body, and contains an oxidizing agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cleaning solution, a method for cleaning a release mold, and a method for producing a ceramic molded body. [Background technology]

[0002] The gel casting method (mold casting method) is known as a method for obtaining ceramic molded bodies. In the gel casting method, a slurry containing inorganic materials, resin, and a dispersion medium is filled into a release mold, and the slurry in the release mold is hardened by gelation. The hardened slurry is then demolded. The hardened body thus obtained is then subjected to processes such as drying, degreasing, and firing to obtain a ceramic molded body. Here, after the hardened body is released from the release mold, some of the components contained in the hardened body may adhere to the release mold. Therefore, Patent Document 1 discloses a method for removing the deposits adhered to the release mold, in which a form (release mold) is immersed in a cleaning liquid containing water, and then the surface of the form is brushed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-131709 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to reuse the release mold repeatedly, the present inventors have tried to clean the release mold after forming a hardened body using a cleaning liquid such as that described in Patent Document 1, but have found that the cleanability of the release mold is sometimes insufficient and there is room for improvement.

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a cleaning liquid that has excellent cleaning properties for release molds used in producing ceramic molded bodies. Another object of the present invention is to provide a method for cleaning a release mold and a method for producing a ceramic molded body. [Means for solving the problem]

[0006] As a result of extensive research into the above-mentioned problems, the present inventors discovered that the use of a cleaning solution containing an oxidizing agent provides excellent cleaning properties for release molds used to produce ceramic molded bodies, and thus arrived at the present invention.

[0007] That is, the inventors have found that the above problems can be solved by the following configuration. [1] A cleaning solution for a release mold for producing a ceramic molded body, A cleaning solution comprising an oxidizing agent. [2] The oxidizing agent is Cl2, MnO 4- , H2O2, H2S2O8, and ClO - The cleaning solution according to [1], comprising at least one selected from the group consisting of: [3] The cleaning solution according to [1] or [2], wherein the concentration of the oxidizing agent is 0.001 to 0.5 mol / L. [4] The cleaning liquid according to any one of [1] to [3], further comprising a pH adjuster. [5] The cleaning solution according to [4], wherein the pH adjuster comprises at least one selected from the group consisting of sodium bicarbonate, potassium hydroxide, sodium hydroxide, tetraethylammonium hydroxide, and tetramethylammonium hydroxide. [6] A method for cleaning a release mold for producing a ceramic molded body, comprising: A method for cleaning a release mold, characterized in that the release mold is immersed in a cleaning liquid containing an oxidizing agent, and then the release mold is taken out of the cleaning liquid and washed with water. [7] The method for cleaning a release mold according to [6], wherein the temperature of the cleaning liquid when the release mold is immersed is 20 to 100°C. [8] The method for cleaning a release mold according to [6] or [7], wherein the release mold after water washing is immersed in pure water and ultrasonically cleaned. [9] a slurry containing a resin is filled into a release mold, the resin in the slurry is cured in the release mold to form a hardened body, the hardened body is then released from the release mold, the hardened body is dried and fired, and the process is repeated to obtain a ceramic molded body; a method for producing a ceramic molded body, the method comprising: after releasing the hardened body from the release mold, cleaning the release mold at least once with a cleaning liquid containing an oxidizing agent.

[10] The method for producing a ceramic molded body according to [9], wherein the release mold has an upper mold, a lower mold arranged to face the upper mold, and a spacer arranged between the upper mold and the lower mold.

[11] The method for producing a ceramic formed body according to [9] or

[10] , wherein the slurry contains the resin, an inorganic material, a crosslinking agent, and a solvent.

[12] the inorganic material comprises silica particles; The method for producing a ceramic formed body according to

[11] , wherein the content of the silica particles is 50 mass % or more based on the total mass of the slurry.

[13] The method for producing a ceramic formed body according to any one of [9] to

[12] , wherein the glass transition temperature of the resin in the slurry is 50 to 200°C.

[14] The method for producing a ceramic formed body according to any one of [9] to

[13] , wherein the resin in the slurry contains an epoxy resin.

[15] The method for producing a ceramic formed body according to any one of [9] to

[14] , wherein the water contact angle of the portion of the release mold that comes into contact with the slurry after washing with the washing liquid is 55 degrees or more. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a release mold for producing a ceramic molded body that has excellent cleaning properties. The present invention also provides a method for cleaning a release mold and a method for producing a ceramic molded body. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic plan view showing an example of a release mold used in the method for producing a ceramic molded body of the present invention. FIG. [Figure 2] 3 is a cross-sectional schematic view of a release mold for explaining an example of a method for forming a hardened body in the method for producing a ceramic molded body of the present invention. FIG. [Figure 3] 2 is a cross-sectional view showing an example of a hardened body after demolding in the method for producing a ceramic molded body of the present invention. FIG. [Figure 4] 1 is a cross-sectional view showing an example of a molded body obtained by the method for producing a ceramic molded body of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] The terms used in the present invention have the following meanings. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In the present specification, in the numerical ranges described in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in the numerical ranges described in the present specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the examples. As used herein, a combination of two or more preferred embodiments is a more preferred embodiment.

[0011] [Cleaning solution] The cleaning solution of the present invention (hereinafter also referred to as "the present cleaning solution") is a release-type cleaning solution for producing a ceramic molded body, and contains an oxidizing agent.

[0012] Although details will be described later, a known method for producing a ceramic molded body using the gel casting method involves filling a release mold with a slurry containing a resin, hardening the resin in the slurry in the release mold to form a hardened body, and then demolding the hardened body from the release mold, drying the demolded hardened body, and firing it to obtain a ceramic molded body. In the production of the above-mentioned ceramic molded body, after the hardened body is released from the release mold, some of the components contained in the hardened body may adhere to the release mold. If this happens, when the same release mold is used to form a hardened body again, the hardened body may adhere to the adhesion of the adhesion material on the release mold, making it difficult to release the hardened body or causing cracks in the hardened body after release. Therefore, a cleaning solution with excellent cleaning properties for the release mold is required in order to reuse the release mold. Here, this cleaning solution is excellent at cleaning release molds used to produce ceramic molded bodies. The reason for this is presumably that the action of the oxidizing agent contained in this cleaning solution promotes the decomposition of deposits (especially cured resins). As such, this cleaning solution has excellent cleaning properties for release molds, and there is an advantage that if the release mold is cleaned with this cleaning solution after demolding, the release mold can be reused.

[0013] [Oxidizing Agent] Specific examples of oxidizing agents include Cl2 and MnO 4- , H2O2, H2S2O8 (peroxodisulfate), ClO - , F2, Br2, I2, HNO3, ClO 3- , ClO 4- Among these, Cl2 and MnO are preferred because they provide a more excellent effect of the present invention. 4- , H2O2, H2S2O8, and ClO - It is preferable that the composition contains at least one selected from the group consisting of:

[0014] The concentration of the oxidizing agent is preferably 0.001 to 0.5 mol / L, more preferably 0.005 to 0.3 mol / L, and even more preferably 0.01 to 0.05 mol / L. When the concentration of the oxidizing agent is 0.001 mol / L or more, the effects of the present invention are more excellent. When the concentration of the oxidizing agent is 0.5 mol / L or less, damage to the release mold can be suppressed, and a decrease in the water contact angle of the portion of the release mold that comes into contact with the slurry can be suppressed, thereby improving the demoldability of the hardened body.

[0015] [pH adjuster] The cleaning solution preferably contains a pH adjuster, since this allows the pH of the cleaning solution to be easily adjusted to a desired range. Specific examples of pH adjusters include sodium bicarbonate, potassium hydroxide, sodium hydroxide, tetraethylammonium hydroxide, tetramethylammonium hydroxide, ammonia, barium hydroxide, propylamine, potassium bicarbonate, etc. Among these, it is preferable to include at least one selected from the group consisting of sodium bicarbonate, potassium hydroxide, sodium hydroxide, tetraethylammonium hydroxide, and tetramethylammonium hydroxide, in view of ease of adjusting the pH of the present cleaning solution.

[0016] The content of the pH adjuster may be appropriately set so that the pH of the cleaning solution falls within the range described below, and is preferably 0.01 to 5 mass %, more preferably 0.1 to 3 mass %, for example.

[0017] 〔water〕 The cleaning solution preferably contains water. The water content may be appropriately set so that the concentration of the oxidizing agent falls within the above-mentioned range, and is preferably 90.00 to 99.99 mass %, more preferably 95.00 to 99.98 mass %, for example.

[0018] [Other ingredients] The cleaning solution may contain other components in addition to those described above, such as surfactants and organic solvents. The content of other components is preferably 5% by mass or less, and more preferably 3% by mass or less.

[0019] [Physical Properties] The pH of the cleaning liquid is preferably greater than 8.0 and less than 13. When the inorganic material contained in the hardened body is silica, if the pH of the cleaning liquid is 8.0 or higher, the silica contained in the hardened body that adheres to the release mold is more easily dissolved, thereby providing better effects of the present invention. The pH can be measured using a known pH meter.

[0020] [Method for preparing cleaning solution] The method for preparing the cleaning solution is not particularly limited, but may include mixing the above-mentioned components. In preparing the cleaning solution, the oxidizing agent may be added in the form of a salt.

[0021] [How to clean the release mold] The method for cleaning a release mold of the present invention (hereinafter also referred to as "this cleaning method") is a method for cleaning a release mold for producing a ceramic molded body, in which the release mold is immersed in a cleaning solution containing an oxidizing agent, and then the release mold is taken out of the cleaning solution and washed with water. It is preferable that this cleaning method further comprises a step of immersing the release mold after water washing in pure water and ultrasonically cleaning it. As an example of a preferred embodiment of the present cleaning method, an embodiment including the following steps W1 to W3 will be described below. Step W1: A step of immersing a release mold in a cleaning solution containing an oxidizing agent Process W2: Process of rinsing the release mold taken out of the cleaning solution with water Process W3: A process in which the release mold after water washing is immersed in pure water and ultrasonically cleaned.

[0022] [Process W1] Step W1 is a step of immersing the release mold in a cleaning liquid containing an oxidizing agent. The cleaning solution used in the step W1 is the same as the main cleaning solution described above, and therefore its description will be omitted. The release mold used in step W1 is a release mold used to prepare a ceramic molded body, and is the same as the release mold used in the ceramic molded body manufacturing method described below, so its description will be omitted. The release mold used in step W1 is preferably the release mold used after a hardened body (described below) has been released from the release mold.

[0023] In step W1, the release mold may be immersed so that the portion that will come into contact with the slurry (described later) comes into contact with the cleaning liquid, or the entire release mold may be immersed in the cleaning liquid.

[0024] In step W1, cleaning using a cleaning liquid may be performed in addition to cleaning using a physical action. Specific examples of cleaning using a physical action include ultrasonic cleaning and two-fluid cleaning in which a mixture of nitrogen gas and a cleaning liquid is sprayed. Among these, ultrasonic cleaning is preferred because it provides better effects of the present invention. Ultrasonic cleaning can be carried out using a known ultrasonic oscillator, and cleaning conditions such as frequency are not particularly limited.

[0025] The temperature of the cleaning liquid when the release mold is immersed is preferably from 20 to 100°C, more preferably from 22 to 80°C, and even more preferably from 25 to 60°C. The time for immersing the release mold in the cleaning solution is preferably 0.5 to 12 hours. When ultrasonic cleaning is also performed when immersing the release mold in the cleaning solution, the time for ultrasonic cleaning (ultrasonic irradiation time) is preferably 5 to 60 minutes.

[0026] Step W1 may be performed only once or may be performed multiple times.

[0027] [Process W2] Step W2 is a step of rinsing the release mold taken out of the cleaning solution with water, which makes it possible to prevent the release mold from being deteriorated by the components contained in the cleaning solution. The water washing method is not particularly limited, and examples thereof include a method of rinsing the release mold with running water, a method of spraying water onto the release mold, and a method of immersing the release mold in water.

[0028] The temperature of the water used for washing is preferably 20 to 80°C, more preferably 25 to 60°C. The washing time is preferably 5 to 60 minutes.

[0029] Step W2 may be performed only once or may be performed multiple times.

[0030] [Process W3] In step W3, the release mold after water washing is immersed in pure water and ultrasonically cleaned, which further enhances the effects of the present invention. Examples of pure water include ion-exchanged water, distilled water, etc. The electrical conductivity of pure water at 25° C. is preferably 1 μS / cm or less.

[0031] Ultrasonic cleaning can be carried out using a known ultrasonic oscillator, and cleaning conditions such as frequency are not particularly limited. The temperature of the pure water in which the release mold is immersed is preferably 20 to 80°C, more preferably 25 to 60°C. The time for immersing the release mold in pure water is preferably 5 to 60 minutes, and the time for ultrasonic cleaning (ultrasonic irradiation time) is preferably 5 to 60 minutes.

[0032] Step W3 may be performed only once or may be performed multiple times.

[0033] [Method for manufacturing ceramic molded body] The method for producing a ceramic molded body of the present invention (hereinafter also referred to as "this production method") includes a step G of filling a release mold with a slurry containing a resin, hardening the resin in the slurry in the release mold to form a hardened body, and then releasing the hardened body from the release mold, drying and firing the hardened body to obtain a ceramic molded body, and includes repeatedly performing the step G, and after releasing the hardened body from the release mold, cleaning the release mold at least once with a cleaning liquid containing an oxidizing agent.

[0034] [Releasable type] FIG. 1 is a schematic plan view showing an example of a release mold used in the present manufacturing method, specifically showing the configuration of each member included in the release mold when viewed from above.

[0035] The release mold 100 has an upper mold 10 , a lower mold 30 arranged so as to face the upper mold 10 , and a spacer 20 arranged between the upper mold 10 and the lower mold 30 .

[0036] The slurry contact area 14 on one surface 10a of the upper mold 10 is an area that comes into contact with the slurry 40 (described later) when the release mold 100 is filled with the slurry 40. A plurality of recesses 12 are provided in the slurry contact area 14 on the surface 10a. The recesses 12 are filled with a slurry 40.

[0037] In the example of Figure 1, a case is shown in which a plurality of recesses 12, each having a circular shape when viewed in a plane, are provided in the upper mold 10, but this is not limited to this, and when the release mold has recesses, the shape, number, arrangement, etc. of the recesses can be changed appropriately depending on the shape of the molded body.

[0038] The diameter 12d of the recess 12 (see FIG. 2 described later) is preferably 1 to 100 mm, more preferably 10 to 80 mm. The depth 12h of the recess 12 (see FIG. 2 described later) is preferably 1 to 80 mm, more preferably 10 to 50 mm. The aspect ratio (depth / diameter), which is the ratio of the depth 12h of the recess 12 to the diameter 12d, is preferably 0.1 or more, more preferably 0.3 or more, and even more preferably 0.5 or more. The upper limit of the aspect ratio of the recesses 12 is preferably 5.0 or less, more preferably 4.0 or less, and even more preferably 3.0 or less, in order to further prevent cracks from occurring in the cured body after demolding. Here, when the shape of the recess when viewed from above is not circular, the diameter of the recess means the circle-equivalent diameter calculated from the projected area of ​​the shape of the recess when viewed from above. The depth 12h of the recess 12 means the maximum depth of the recess 12. The diameter 12d and depth 12h of the recess 12 can be measured using, for example, a one-shot 3D shape measuring instrument VR-6000 manufactured by KEYENCE Corporation.

[0039] In the example of FIG. 1, the upper mold 10 has a rectangular shape when viewed from above, but is not limited to this and may have a polygonal shape (excluding a rectangle), a circle, an ellipse, or the like. The thickness of the upper mold 10 is not particularly limited, but is preferably 10 to 150 mm.

[0040] The slurry contact area 34 on one surface 30a of the lower mold 30 is an area that comes into contact with the slurry 40 (described later) when the release mold 100 is filled with the slurry 40. In the example of FIG. 1, a mode in which no recess is provided in the lower mold 30 is shown, but the present invention is not limited to this, and the lower mold 30 may have a recess.

[0041] In the example of FIG. 1, the lower mold 30 has a rectangular shape when viewed from above, but is not limited to this and may have a polygonal shape (excluding a rectangle), a circle, an ellipse, or the like. The thickness of the lower mold 30 is not particularly limited, but is preferably 2 to 150 mm.

[0042] The spacer 20 has a spacer body 22 and a filling port 23 for filling the inside of the release mold 100 with the slurry 40 . The release mold 100 has the spacer 20, which has the advantage of making it easy to release from the mold.

[0043] When filling the inside of the release mold 100 with the slurry 40, one surface 20a of the spacer body 22 is positioned so as to contact the surface 10a of the upper mold 10, and the other surface 20b of the spacer body 22 is positioned so as to contact the surface 30a of the lower mold 30 (see Figure 2 described below). In the example of Figure 1, the shape of the spacer body 22 when viewed in a plane is shown as a circular ring with a cutout in the portion corresponding to the filling port 23, but this is not limited to this and can be changed as appropriate depending on the shape of the molded body. The thickness of the spacer 20 (spacer body 22) is not particularly limited and can be set appropriately.

[0044] The filling port 23 is used when filling the inside of the release mold 100 with the slurry 40 . The diameter (circle equivalent diameter) of the filling port 23 is preferably 0.2 to 3 mm.

[0045] The slurry contact area 24 of the spacer 20 is composed of the inner wall surface 24a of the spacer body 22 and the inner wall surface 24b of the filling port 23, and is the area that comes into contact with the slurry 40 when the slurry 40 is filled into the release mold 100.

[0046] In the example of FIG. 1, an embodiment in which the release mold 100 has the spacer 20 is shown, but the present invention is not limited to this, and the release mold used in the present manufacturing method does not necessarily have to have a spacer. Furthermore, although the embodiment in which the release mold 100 is composed of multiple parts, namely the upper mold 10, the spacer 20, and the lower mold 30, is shown, the present invention is not limited to this, and the release mold used in the present manufacturing method may be composed of a single part.

[0047] The surface roughness (Ra) of the parts of the release mold that come into contact with the slurry (in the example of FIG. 1, the surfaces of the slurry contact areas 14, 24, and 34) is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less, in order to further suppress the occurrence of cracks in the hardened body after demolding. The lower limit of the surface roughness (Ra) is usually 0.001 μm. The surface roughness (Ra) means the arithmetic mean roughness and is measured by a method conforming to JIS B 0601:2013.

[0048] The release mold preferably contains a resin. Specific examples of resins that can be contained in the release mold include cyclic olefin resins, polystyrene, vinyl chloride resins, acrylic resins, methacrylic resins, and olefin resins (e.g., polypropylene, etc.). In terms of superior demoldability of the cured product, acrylic resins, methacrylic resins, cyclic olefin resins, and olefin resins are preferred, with methacrylic resins and cyclic olefin resins being more preferred. The release mold may contain one type of resin alone or two or more types of resin.

[0049] A cyclic olefin resin (cycloolefin polymer) is a polymer of a cyclic olefin (cycloolefin), and may be a homopolymer of a cyclic olefin, a copolymer of multiple cyclic olefins, or a copolymer of a cyclic olefin and another olefin. The cyclic olefin resin may be a polymer obtained by hydrogenating at least a portion of the carbon-carbon unsaturated bonds of a cyclic olefin polymer. Specific examples of cyclic olefins include norbornene, cyclopentadiene, dicyclopentadiene, cyclohexadiene, methanotetrahydrofluorene, tetracyclododecene, and derivatives thereof. The cyclic olefin may have at least one group selected from the group consisting of an alkyl group, an alkylene group, a vinyl group, an alkoxycarbonyl group, and an alkylidene group. Specific examples of other olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, and derivatives thereof. The cyclic olefin resin can be obtained by addition polymerization, metathesis polymerization, etc. of these cycloolefins. The cyclic olefin resin may also be a cyclized polymer of a conjugated diene. As the cyclic olefin resin, commercially available products may be used, and examples thereof include Zeonor (manufactured by Zeon Corporation), Zeonex (manufactured by Zeon Corporation), and Apel (manufactured by Mitsui Chemicals, Inc.).

[0050] As shown in FIG. 1, when a release mold 100 having an upper mold 10, a lower mold 30, and a spacer 20 is used, at least one part selected from the group consisting of the upper mold 10, the lower mold 30, and the spacer 20 preferably contains a resin, more preferably contains an acrylic resin, a methacrylic resin, an olefin resin, or a cyclic olefin resin, and even more preferably contains a cyclic olefin resin. In order to obtain a more excellent effect of the present invention, it is preferable that the part having the recess (upper die 10 in the example of FIG. 1) in the release die contains a resin, more preferably an acrylic resin, a methacrylic resin, an olefin resin, or a cyclic olefin resin, and even more preferably a cyclic olefin resin.

[0051] The release mold may contain rubber. In this case, it is preferable that at least one of the components constituting the release mold contains rubber. Specifically, as shown in FIG. 1, when a release mold 100 having an upper mold 10, a lower mold 30, and a spacer 20 is used, an embodiment in which the spacer 20 contains rubber can be mentioned. Specific examples of rubber that can be contained in the release mold include silicone rubber, fluorine-based rubber, styrene-butadiene rubber, and chloroprene rubber, with silicone rubber being preferred because of its excellent chemical stability. The spacer 20 is not limited to a configuration containing rubber, and may contain a resin such as a fluororesin (for example, polytetrafluoroethylene).

[0052] The release mold may contain glass. In this case, at least one of the components constituting the release mold may contain glass. Specifically, as shown in FIG. 1, when a release mold 100 having an upper mold 10, a lower mold 30, and a spacer 20 is used, for example, the lower mold 30 may contain glass. Furthermore, the lower mold 30 is not limited to an embodiment in which it contains glass, and it is also preferable that the lower mold 30 contains a resin such as the above-mentioned cyclic olefin resin, polystyrene, vinyl chloride resin, acrylic resin, methacrylic resin, or olefin resin. A preferred embodiment of the release mold in the present invention is one in which both the upper mold 10 and the lower mold 30 are made of resin. In this case, the upper mold 10 and the lower mold 30 preferably contain an acrylic resin, a methacrylic resin, an olefin resin, or a cyclic olefin resin, and more preferably a methacrylic resin or a cyclic olefin resin.

[0053] When the release mold contains a resin, the content of the resin contained in the release mold is preferably 60% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on the total mass of the release mold, in order to obtain better effects of the present invention. When the release mold contains a resin, the upper limit of the content of the resin contained in the release mold is preferably 100% by mass, more preferably 99% by mass or less, and even more preferably 98% by mass or less. In order to obtain a more excellent effect of the present invention, it is preferable that the content of the resin contained in at least the part provided with the recess (upper mold 10 in the example of FIG. 1) in the release mold satisfies the above value.

[0054] The release mold may contain other components in addition to those described above, such as inorganic fillers and metals. The content of other components that may be contained in the release mold is preferably 2% by mass or less, and more preferably 1% by mass or less, based on the total mass of the release mold.

[0055] The water absorption of the release mold is preferably less than 0.1%, more preferably 0.05% or less, and even more preferably 0.03% or less. When the water absorption of the release mold is less than 0.1%, swelling of the release mold due to cleaning liquid is suppressed, and deformation of the release mold can be suppressed. In addition, molded articles with excellent precision can be obtained. Furthermore, when the hardened body is demolded in liquid (particularly in water), swelling of the release mold is suppressed, and therefore the release mold can be easily reused in the production of hardened bodies. The water absorption rate of the release mold is measured by a method in accordance with JIS K 7209:2000.

[0056] The method for producing the release mold can be any known method and is not particularly limited. For example, when a release mold containing a resin is to be obtained, an injection molding method or the like can be used.

[0057] 〔slurry〕 The slurry preferably contains a resin, and further contains an inorganic material, a crosslinking agent, and a solvent.

[0058] <Resin> The resin in the slurry is preferably a curable resin. The curable resin is a resin that begins to harden upon heating or upon reaction with a crosslinking agent, etc., and is preferably a resin having a curable group. Specific examples of the curable group include an epoxy group (oxiranyl group), a hydroxy group, a carboxy group, an amino group, an alkoxy group, and an isocyanate group.

[0059] Specific examples of the resin include melamine resin, phenol resin, epoxy resin, acrylic resin, urethane resin, etc. Among them, epoxy resin is preferred in that it provides a molded product with high shape retention and cures in the air. Specific examples of epoxy resins include diglycidyl ether type epoxy resins of bisphenols such as bisphenol A type and bisphenol F type, phenol novolac type epoxy resins, cresol novolac type epoxy resins, glycidyl amine type epoxy resins, glycidyl ether type epoxy resins such as aliphatic epoxy resins, glycidyl ester type epoxy resins, methyl glycidyl ether type epoxy resins, cyclohexene oxide type epoxy resins, and rubber-modified epoxy resins. Examples of monomers that react to form acrylic resins include acrylic monomers such as acrylic acid, methacrylic acid amide, methacrylic acid, methoxy(polyethylene glycol) monomethacrylate, alkyl acrylate, alkyl methacrylate, dimethylaminoethyl methacrylate, hydroxyalkyl acrylate, hydroxyalkyl methacrylate, methacrylatoethyltrimethylammonium chloride, etc. These acrylic monomers may be used alone or in combination of two or more. The acrylic resin may also be a copolymer of the above acrylic monomer with another monomer, such as n-vinylpyrrolidone, acrylamide, alkylacrylamide, alkylmethacrylamide, dimethylaminopropylmethacrylamide, hydroxyalkylacrylamide, hydroxyalkylmethacrylamide, methacrylamidepropyltrimethylammonium chloride, p-styrenesulfonic acid, or p-styrenesulfonate.

[0060] When an epoxy resin is used as the resin, the average molecular weight is preferably 20 to 30,000. The average number of epoxy functional groups in the epoxy resin is preferably 2 to 10. This ensures a certain level of strength when demolded and also ensures a sufficient usable time when cast.

[0061] The glass transition temperature (Tg) of the resin in the slurry is preferably from 50 to 200°C, more preferably from 60 to 190°C, and even more preferably from 70 to 180°C, from the viewpoint of ease of handling. The Tg of the resin is the midpoint glass transition temperature measured by differential scanning calorimetry (DSC) in accordance with JIS K 7121:2012.

[0062] The content of the resin in the slurry is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, and even more preferably 1 to 15% by mass, based on the total mass of the slurry.

[0063] <Inorganic materials> The slurry preferably contains an inorganic material, and the inorganic material is preferably in particulate (powder) form. Specific examples of inorganic materials include silica, silicon nitride, aluminum nitride, titanium nitride, silicon carbide, aluminum oxide, and zirconium oxide, and among these, silica is preferred because it provides better effects of the present invention.

[0064] From the viewpoint of shape stability, the content of the inorganic material (preferably silica particles) is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 65% ​​by mass or more, based on the total mass of the slurry. From the viewpoint of handling of the slurry, the content of the inorganic material (preferably silica particles) is preferably 98 mass % or less, more preferably 95 mass % or less, and even more preferably 90 mass % or less, based on the total mass of the slurry.

[0065] The mass ratio of the inorganic material (preferably silica particles) to the resin (inorganic material:resin) in the slurry is preferably 50:50 to 99:1, more preferably 82:18 to 98:2, and even more preferably 87:13 to 94:6, in order to satisfactorily form a molded body.

[0066] <Crosslinking agent> The slurry preferably contains a cross-linking agent. The crosslinking agent cures the resin by crosslinking, and may be selected depending on the resin to be used. For example, examples of crosslinking agents (curing agents) for epoxy resins include amine-based curing agents, acid anhydride-based curing agents, polyamide-based curing agents, etc. Amine-based curing agents are preferred because they react quickly, and acid anhydride-based curing agents are preferred because they can give cured products with excellent thermal shock resistance. Examples of the amine-based curing agent include aliphatic amines, alicyclic amines, aromatic amines, modified polyaminoamides, and modified aliphatic polyamines, and any of monoamines, diamines, triamines, and polyamines can be used. Examples of the acid anhydride curing agent include methyltetrahydrophthalic anhydride and dibasic acid polyanhydride.

[0067] The content of the crosslinking agent is preferably 1 to 50 parts by mass, more preferably 5 to 20 parts by mass, relative to 100 parts by mass of the resin in the slurry.

[0068] <Solvent> The slurry preferably contains a solvent. By using a solvent, the viscosity of the mixture of raw materials used can be adjusted to form a slurry, which can facilitate filling of the slurry into the release mold. Specific examples of the solvent include pure water such as ion-exchanged water and distilled water, alcohols, and other organic solvents. Among these, it is preferable to use an aqueous solvent from the viewpoint of production costs and environmental impact.

[0069] The content of the solvent is preferably from 5 to 39 mass %, more preferably from 10 to 45 mass %, and even more preferably from 15 to 40 mass %, based on the total mass of the slurry.

[0070] <Other ingredients> The slurry may contain components other than those mentioned above (hereinafter also referred to as "other components"). Specific examples of other components include curing catalysts, dispersants, pH adjusters, sintering aids, surfactants, viscosity adjusters, etc. These may be added in the required amounts as needed.

[0071] <Method of preparing slurry> The method for preparing the slurry is not particularly limited, but for example, a method may be used in which a dispersion containing an inorganic material and a solvent is obtained, and then components other than the inorganic material are mixed with the dispersion.

[0072] [Process] This manufacturing method includes a step G in which a release mold is filled with a slurry containing a resin, the resin in the slurry is cured in the release mold to form a cured body, the cured body is then released from the release mold, and the released cured body is dried and fired to obtain a molded body. Here, it is preferable that step G further includes a step of degreasing the dried cured body after drying the released cured body and before firing. In this manufacturing method, step G is repeatedly carried out. The present manufacturing method also includes, after releasing the cured body from the release mold, washing the release mold at least once with a cleaning liquid containing an oxidizing agent. As an example of a preferred embodiment of the present production method, an embodiment including the following steps G1 to G5 and step W will be described below. Step G1: A step of filling a resin-containing slurry into a resin-containing mold and curing the resin in the slurry in the mold to form a cured body. Process G2: Process of releasing the hardened body from the release mold Step G3: Drying the demolded hardened body Process G4: Degreasing the hardened body after drying Step G5: A step of firing the degreased hardened body to obtain a molded body. Step W: A step of cleaning the release mold at least once with a cleaning solution containing an oxidizing agent after the hardened body is released from the release mold.

[0073] <Process G1> Step G1 is a step of filling a resin-containing slurry into a resin-containing release mold, and curing the resin in the slurry within the release mold to form a cured body. 2 is a schematic cross-sectional view of a release mold 100 for explaining an example of a method for forming a cured body 42 in this manufacturing method, and is a cross-sectional view taken along line A-A' of the release mold 100 in FIG. 1. Step G1 will be described with reference to FIG. 2.

[0074] 2, the spacer body 22 is placed so that one surface 20a thereof contacts the surface 10a of the upper mold 10, and the other surface 20b thereof contacts the surface 30a of the lower mold 30. This creates a space defined by the upper mold 10, the spacer 20, and the lower mold 30. Next, the slurry 40 is poured into the spacer 20 through the filling port 23 (see FIG. 1) so that the space generated inside the release mold 40 is filled with the slurry 40. The method for pouring the slurry is not particularly limited, and examples thereof include a method using a known pump or the like.

[0075] Next, the resin in the slurry 40 is cured to obtain a cured body 42. Here, depending on the type of resin in the slurry and the type of crosslinking agent, the resin may be cured at room temperature (18 to 25°C) or under heat (for example, 40 to 80°C). For example, when the above-mentioned epoxy resin is used as the resin in the slurry 40, the resin can be cured at room temperature. Here, since the release mold 100 contains a resin, when the resin is cured at room temperature, deterioration of the release mold 100 due to heat can be suppressed. When the resin in the slurry is cured at room temperature, the curing time is preferably, for example, 5 to 48 hours. When the resin in the slurry is cured under heating, the curing time is preferably, for example, 1 to 24 hours.

[0076] <Process G2> Step G2 is a step of releasing the hardened body from the release mold. 2, the cured body 42 can be released, for example, by separating the upper mold 10, the lower mold 30, and the release mold 100 along the thickness direction, and then removing the spacer 20. In this way, the cured body 42 after release is obtained (see FIG. 3).

[0077] The demolding of the cured body may be carried out in the air, but is preferably carried out in a liquid. When the demolding of the cured body is carried out in a liquid, the liquid penetrates between the cured body and the release mold, making it easier to demold the cured body, and as a result, the occurrence of cracks in the cured body is further suppressed. Examples of the liquid include water and ethanol, with water being preferred. The temperature of the liquid is preferably 18 to 30°C. The time for immersing the cured body in the liquid is preferably 1 to 30 minutes.

[0078] <Process G3> Step G3 is a step of drying the demolded hardened body. This allows volatile components such as the solvent contained in the hardened body and moisture adhering to the surface of the hardened body to be removed. By going through step G3, the hardened body can be densified.

[0079] In step G3, drying is preferably carried out under conditions that do not cause cracks in the cured product. In this case, the drying temperature in step G3 is preferably 18 to 90° C. Furthermore, the relative humidity during drying of the cured body after demolding is preferably 50 to 99%. The drying time may be adjusted as appropriate.

[0080] Step G3 is preferably carried out, for example, until the ratio of the mass of the solvent in the cured body after drying to the mass of the solvent in the cured body before drying (after drying / before drying) becomes 10% or less.

[0081] <Process G4> Step G4 is a step of degreasing the dried cured body. This allows the resin, non-volatile solvent, etc. to be removed from the dried cured body. In step G4, it is preferable to almost completely remove components that inhibit the firing in step G5. By performing step G4, the occurrence of voids, etc. in the molded body obtained in step G5 can be suppressed.

[0082] The degreasing method in step G4 is preferably a method of heating the cured body after drying. In this case, the heating temperature is preferably 200 to 800° C. The heating time is preferably 5 to 96 hours.

[0083] Step G4 is preferably carried out until the ratio of the mass of resin in the cured body after degreasing to the mass of resin in the cured body before degreasing (after degreasing / before degreasing) becomes 1% or less, for example.

[0084] <Process G5> Step G5 is a step of firing the degreased cured body to obtain a molded body. When the cured body contains an inorganic material, the inorganic material in the cured body is sintered by firing to obtain a sintered body. For example, when silica particles are used as the inorganic material, the silica particles are sintered by firing to obtain a quartz glass molded body.

[0085] The firing method in step G5 can be any known method and is not particularly limited. For example, the firing temperature in step G5 is preferably 1000 to 1500° C. The firing time is preferably 0.1 to 48 hours.

[0086] The shape, size, thickness, etc. of the molded body obtained in step G5 are not particularly limited and are designed appropriately depending on the application. An example of the molded body obtained in step G5 is the molded body 44 shown in FIG. In the molded body 44, the ratio (H1 / H2) of the maximum thickness H1 to the minimum thickness H2 is preferably greater than 1, more preferably 1.2 or greater, and even more preferably 1.3 or greater. The upper limit of the ratio (H1 / H2) is preferably 80 or less, more preferably 60 or less, and even more preferably 50 or less.

[0087] The surface roughness (Ra) of the molded body obtained in step G5 is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 1 μm or less. The lower limit of the surface roughness (Ra) of the molded body obtained in step G5 is usually 0.001 μm. The surface roughness (Ra) of the molded body obtained in step G5 means the arithmetic mean roughness, and is measured by the method described above. As a method for obtaining a molded article having a surface roughness (Ra) of 10 μm or less, for example, a method using a release mold having a surface roughness Ra of 10 μm or less can be mentioned.

[0088] In this manufacturing method, step G (specifically, the series of steps G1 to G5) is repeatedly carried out, and therefore, in this manufacturing method, the release mold is repeatedly used to manufacture the ceramic molded body. The number of times step G is carried out is 2 or more, preferably 3 or more, and more preferably 4 or more. There is no particular upper limit to the number of times step G is carried out, but it is preferably 10 or less.

[0089] <Process W> Step W is a step of cleaning the release mold at least once with a cleaning solution containing an oxidizing agent after the cured body is released from the release mold. That is, in this production process, step W is performed after step G2, which is included in at least one step G among the steps G that are repeatedly performed.

[0090] The timing of performing the step W will be described in more detail. For example, when step G is performed three times in this manufacturing method, step W may be performed at least one of timings 1 to 3 shown below. Timing 1: After the first process G2 is performed and before the second process G is performed Timing 2: After the second process G2 is performed and before the third process G is performed Timing 3: After performing step G2 in the third step G

[0091] It is preferable to carry out this step after using the release mold and before the next step G, as this can further improve the demoldability of the hardened body and further suppress the occurrence of cracks in the hardened body. Specifically, when step G is performed three times as described above, it is preferable to perform step W at timing 1 or timing 2.

[0092] Step W2 is preferably performed every time step G2 is performed, since this can further improve the demoldability of the cured body and further suppress the occurrence of cracks in the cured body. Specifically, when step G is performed three times as described above, it is preferable to perform step W at both timing 1 and timing 2.

[0093] The cleaning solution used in the step W is the same as the main cleaning solution described above, and therefore its description will be omitted. The step W is preferably an embodiment that includes the step W1 in the present cleaning method described above, and more preferably an embodiment that includes the steps W1 to W3 in the present cleaning method described above.

[0094] The water contact angle of the part of the release mold that comes into contact with the slurry after washing with the washing liquid is preferably 55 degrees or more, more preferably 75 degrees or more, and even more preferably 80 degrees or more, in order to further improve the demoldability of the hardened body. The upper limit of the contact angle is preferably 95 degrees or less. The contact angle can be measured as follows. Distilled water is dropped onto the portion of the release mold that will come into contact with the slurry, and the water contact angle is measured using a contact angle measuring device (for example, product name "SImage AUTO 100" manufactured by Excimer Corporation). The average value measured at three locations is taken as the water contact angle. The θ / 2 method is used to calculate the water contact angle.

[0095] <Other processes> The present manufacturing method may include a step of drying the release mold in order to remove moisture and the like that has adhered to the surface of the release mold after cleaning the release mold. The drying method is not particularly limited, and examples thereof include a method of wiping off moisture and the like that has adhered to the surface of the release mold with a cloth or the like, a method of drying with a dryer, and natural drying. [Example]

[0096] The present invention will be described in detail below with reference to examples. Examples 1 to 8 are working examples, and Examples 9 and 10 are comparative examples. However, the present invention is not limited to these examples. The blending amounts of each component in the tables below are based on mass.

[0097] [Preparing release mold 1] An upper mold (diameter 120 mm, thickness 8 mm, shape in plan view: circular) made of methacrylic resin (trade name "Parapet", manufactured by Kuraray Co., Ltd.) was prepared, with 44 recesses (diameter 4.76 mm, depth 2.38 mm) formed on its surface. All recesses were formed within a 90 mm diameter area of ​​the upper mold. In addition, a lower mold (diameter 120 mm, thickness 8 mm, shape when viewed from above: circular) made of methacrylic resin (product name "Parapet", manufactured by Kuraray Co., Ltd.) with no recesses on the surface was prepared. A ring-shaped silicone rubber (outer diameter 100 mm, inner diameter 90 mm, thickness 1.5 mm) was provided with a 3 mm diameter notch to serve as a slurry filling port to obtain a release type spacer. The upper mold, spacer, and lower mold were stacked in this order to form a release mold 1.

[0098] [Preparing release mold 2] An upper mold and a lower mold were prepared that had the same shape as the release mold 1, except that the material constituting the upper mold and the lower mold was a cyclic olefin resin (trade name "ZEONEX", manufactured by Zeon Corporation). In addition, a spacer similar to that of the release mold 1 was prepared. The upper mold, spacer, and lower mold were stacked in this order to form a release mold 2.

[0099] [Preparation of slurry] A dispersion was obtained by dispersing raw silica powder (purity 99.9% or more, average particle size 100 nm) (64.0 parts by mass) and a solvent (37.0 parts by mass) in which a pH adjuster was added to water to adjust the pH to 13 using an ultrasonic homogenizer. The obtained dispersion (94.1 parts by mass), a water-soluble epoxy resin (Tg: 156°C) (5.0 parts by mass), and an aliphatic amine curing agent (0.9 parts by mass) were mixed and degassed using a planetary centrifugal mixer equipped with a vacuum pump to obtain slurry 1.

[0100] [Example 1 to Example 8] Cleaning solutions 1 to 8 of Examples 1 to 8 were obtained by mixing water, an oxidizing agent, and a pH adjuster so that the concentration of the oxidizing agent and the pH of the cleaning solution were as shown in Table 1.

[0101] [Example 9] Water and a pH adjuster were mixed so that the pH of the cleaning solution would be the value shown in Table 1, thereby obtaining cleaning solution 9 of Example 9.

[0102] [Example 10] Water was used as wash solution 10 in Example 10.

[0103] [Cleaning test] First, the slurry 1 was filled into a release mold shown in Table 1, and then the mold was left standing at 23° C. for 48 hours to harden the resin in the slurry 1 within the release mold, thereby forming a hardened body (step G1). Next, the cured body was released from the release mold (step G2). Specifically, the release mold was immersed in water, and then the lower mold was removed while still immersed in water, and then the spacer and the upper mold were removed from the cured body.

[0104] Next, using any of the cleaning solutions of Examples 1 to 10, the release mold after demolding was cleaned. Specifically, a cleaning solution was filled into a resin container. Then, the demolded release mold placed on a rack was immersed in the cleaning solution in the resin container, and the resin container was then placed in an ultrasonic cleaning tank and ultrasonically cleaned for 30 minutes. After the ultrasonic cleaning, the resin container was left standing for 3 hours (step W1). Note that step W1 was carried out while the temperature of the cleaning solution was maintained at 60°C. Next, the rack on which the release mold was placed was taken out of the cleaning solution, and the release mold was rinsed with running water (step W2). After rinsing with running water, the release mold was immersed in pure water and subjected to ultrasonic cleaning for 5 minutes (step W3). Subsequently, the process W2 and the process W3 were carried out two more times in this order to complete the cleaning of the release mold, and the moisture adhering to the release mold was wiped off. In this way, the release mold after demolding was cleaned, and a cleaned release mold was obtained.

[0105] The above-mentioned steps G1 and G2 and the cleaning of the release mold were repeated multiple times in this order. The number of times the release mold could be used without any problems in demolding the cured body was counted, and the cleanability was evaluated according to the following criteria. The results are shown in Table 1. A rating of B or higher can be said to be excellent in the cleanability of the release mold. The term "poor demolding" refers to the fact that the cured body adheres to the release mold and cannot be demolded, and that cracks occur in the cured body after demolding. A: The release mold can be used more than 10 times. B: The release mold can be used 2 to 9 times. C: Release mold can be used only once

[0106] [Table 1]

[0107] As shown in Table 1, it was confirmed that the use of a cleaning solution containing an oxidizing agent provided excellent cleaning properties for a release mold for producing a ceramic molded body (Examples 1 to 8).

[0108] Furthermore, using the hardened bodies obtained in the cleaning tests of Examples 1 to 8 described above, ceramic molded bodies were produced by the following method. Specifically, the hardened body removed from the cleaned release mold was dried for 24 hours under conditions of 60°C and 80% RH (step G3). After that, the dried hardened body was degreased by holding it in an electric furnace at 550°C for 24 hours (step G4). Next, the degreased molded body was fired in a vacuum at 1400°C to obtain a ceramic molded body, which was a molded body of quartz glass (step G5). [Explanation of symbols]

[0109] 10 Upper mold 10a surface 12 recess 12d diameter 12h depth 14 Slurry contact area 20 spacers 20a surface 20b surface 22 Spacer body 23 Filling port 24 Slurry contact area 24a Inner wall 24b Inner wall 30 Lower mold 30a surface 34 Slurry contact area 40 Slurry 42 Hardened body 44 Molded body 100 Release mold H1 Maximum thickness H2 minimum thickness

Claims

1. A cleaning liquid for a release mold for producing a ceramic molded body, A cleaning solution comprising an oxidizing agent.

2. The oxidizing agent is Cl ２ , MnO ４－ , H ２ O ２ , H ２ S ２ O ８ , and ClO － The cleaning solution according to claim 1 , comprising at least one selected from the group consisting of:

3. 3. The cleaning solution according to claim 1, wherein the concentration of the oxidizing agent is 0.001 to 0.5 mol / L.

4. The cleaning solution according to claim 1 or 2, further comprising a pH adjuster.

5. 5. The cleaning solution according to claim 4, wherein the pH adjuster comprises at least one selected from the group consisting of sodium bicarbonate, potassium hydroxide, sodium hydroxide, tetraethylammonium hydroxide, and tetramethylammonium hydroxide.

6. A method for cleaning a release mold for producing a ceramic molded body, comprising: A method for cleaning a release mold, characterized in that the release mold is immersed in a cleaning liquid containing an oxidizing agent, and then the release mold is taken out of the cleaning liquid and washed with water.

7. 7. The method for cleaning a release mold according to claim 6, wherein the temperature of the cleaning liquid when the release mold is immersed is 20 to 100°C.

8. 8. The method for cleaning a release mold according to claim 6 or 7, wherein the release mold after being washed with water is immersed in pure water and ultrasonically cleaned.

9. a slurry containing a resin is filled into a mold release die, the resin in the slurry is cured in the mold release die to form a hardened body, the hardened body is then released from the mold release die, the hardened body that has been released is dried and fired, and the process is repeated to obtain a ceramic molded body; a step of removing the hardened body from the release mold and then cleaning the release mold at least once with a cleaning liquid containing an oxidizing agent.

10. 10. The method for manufacturing a ceramic molded body according to claim 9, wherein the release mold has an upper mold, a lower mold arranged to face the upper mold, and a spacer arranged between the upper mold and the lower mold.

11. The method for producing a ceramic formed body according to claim 9 or 10, wherein the slurry contains the resin, an inorganic material, a cross-linking agent, and a solvent.

12. the inorganic material comprises silica particles; The method for producing a ceramic formed body according to claim 11, wherein the content of the silica particles is 50 mass% or more with respect to the total mass of the slurry.

13. The method for producing a ceramic formed body according to claim 9 or 10, wherein the glass transition temperature of the resin in the slurry is 50 to 200°C.

14. The method for producing a ceramic molded body according to claim 9 or 10, wherein the resin in the slurry includes an epoxy resin.

15. 11. The method for producing a ceramic formed body according to claim 9, wherein a water contact angle of a portion of the release mold that comes into contact with the slurry after washing with the washing liquid is 55 degrees or more.

Images