JP7345785B2 - Method for producing a ceramic raw material compound and method for producing a ceramic article using the ceramic raw material compound obtained by the method - Google Patents

Description

The present invention relates to a method for manufacturing a ceramic raw material compound that is suitably used in manufacturing ceramic articles such as ceramic mill blanks for dental processing, and to manufacturing ceramic articles using the ceramic raw compound obtained by the method. Regarding how to.

Manufacturing of ceramic articles generally involves preparing a composition (compound) containing ceramic inorganic powder and an organic binder, molding it into the desired shape, removing the organic binder, and then sintering. It is manufactured by As the organic binder, organic resins such as polyvinyl alcohol, ethylene resin, and wax such as paraffin are generally used.

For example, Patent Document 1 describes ``a zirconia sintering process characterized by having an alkali treatment step of contacting a molded body containing an organic binder and zirconia with an alkaline aqueous solution, and a sintering process of sintering the molded body. The invention relates to a method for producing a compact, and specifically, a compound is obtained by kneading zirconia powder and an olefin resin-based organic binder at 170°C, and the obtained compound is injection molded to produce a molded object. It is described that after the obtained zirconia sintered body was obtained, it was treated with an aqueous alkali solution, degreased at 450°C in the air, and further sintered at 1500°C in the air for 2 hours to obtain a zirconia sintered body. In addition, Patent Document 2 describes a process of kneading an inorganic fine powder made of sinterable metal or ceramics and an organic binder resin to prepare a compound, and then injection molding this compound to form a molded body. Next, the obtained molded body is held in an alkaline aqueous solution and the binder resin is selectively hydrolyzed and removed to obtain a degreased body. Next, this degreased body is sintered, The invention relates to a method for producing a powder sintered body characterized by comprising a step of obtaining a powder sintered body.

On the other hand, with advances in digital technology, a method for obtaining ceramic articles by sintering a molded body obtained by stereolithography using a so-called 3D printer or the like is also known. For example, Patent Document 3 describes a method for manufacturing a zirconia molded body for forming a dental material, which includes a step of stereolithography using a composition containing zirconia particles, a polymerizable monomer, and a photopolymerization initiator. A manufacturing method is described in which the average primary particle diameter of the zirconia particles is 30 nm or less, and the monodispersity of the zirconia particles is 50% or more. Here, stereolithography is a technology in which a molded object is formed layer by layer by locally curing the layers by irradiating the above composition with light, and is used to form a molded object layer by layer. It is said that a molded article having a desired shape can be obtained by irradiating light according to slice data for each layer based on three-dimensional CAD data corresponding to a three-dimensional shape. In addition, in the specific example of Patent Document 3, as the above composition, an organic solvent is added to an aqueous zirconia slurry in which zirconia fine particles are dispersed in water, and then the water is removed by azeotropy, thereby converting the dispersion medium from the water to the organic solvent. A slurry obtained by a complicated method such as mixing it with a polymerizable monomer is used, and after stereolithography, it is dried for a long time (5 days) and then heated to 400°C to temporarily stabilize it. A ceramic article (artificial tooth) is obtained by obtaining a sintered body and sintering it at 1050°C.

JP2016-190760 JP 2001-234202 JP2019-26594

In the method disclosed in Patent Document 3, the molded body before sintering can be manufactured using stereolithography technology, so it is possible to obtain a molded body in a desired shape without separately preparing a mold die etc. On the other hand, it is necessary to prepare a raw material composition in which zirconia primary particles of 30 nm or less are dispersed in a polymerizable monomer by the complicated method described above. For example, it is unsuitable for mass production of molded bodies having the same (standardized) shape, and thus ceramic articles.

On the other hand, in the methods described in Patent Documents 1 and 2, the compound is in the form of powder or pellets and is easy to handle, and when molding, injection molding, press molding, cast molding, etc. Since a molding method can be applied, it can be said that this method is suitable for mass producing ceramic articles of a predetermined shape on a certain scale or larger.

However, when preparing a compound, it is necessary to knead an organic binder such as a thermoplastic resin with the ceramic inorganic powder in order to improve moldability. It is necessary to perform kneading at a high temperature using special equipment such as a pressure kneader, a double-arm kneader, or a screw extruder. Therefore, even for products with standardized shapes such as ceramic mill blanks for dental processing, when manufacturing products on a relatively small production scale, equipment costs are high and energy costs are high. In other words, it was not necessarily an economical method.

Therefore, the present invention aims to create a ceramic raw material compound that has sufficient moldability without requiring kneading using large equipment such as a pressure kneader or screw extruder, and without requiring treatment at high temperatures of 100°C or higher. The objective is to provide a manufacturing method.

The present invention solves the above problems by the following technical means.

That is, the first embodiment of the present invention includes 100 parts by mass of sinterable ceramic raw material inorganic powder (A), and has a plurality of polymerizable groups in the molecule , or one polymerizable group and at least one polymerizable group. 1 part by mass or more and less than 25 parts by mass of a polymerizable monomer (B) consisting of an organic compound having one hydrogen-bonding group and a molecular weight of 50 or more and 1000 or less, the method comprising: A monomer solution (D) in which the polymerizable monomer (B) is dissolved in an organic solvent (C) in an amount of 1 part by mass or more and less than 25 parts by mass with respect to 100 parts by mass of the ceramic raw material inorganic powder (A). and 100 parts by mass of the ceramic inorganic powder (A) to prepare a slurry in which the ceramic raw material inorganic powder (A) is dispersed in the monomer solution (D), and the slurry A method for producing the ceramic raw material compound (hereinafter also referred to as "the raw material production method of the present invention"), comprising a solvent removal step of removing the organic solvent (C) from the slurry obtained in the step of ).

In the raw material manufacturing method of the present invention, the ceramic raw material compound preferably does not contain a polymerization initiator, and the ceramic raw material compound is preferably in the form of powder or granules .

A second aspect of the present invention includes a step of manufacturing a ceramic raw compound powder by the method of the first aspect of the present invention, molding the ceramic raw compound powder obtained in the step, and forming a ceramic raw compound powder into a predetermined shape. A method for producing a ceramic article (hereinafter referred to as , also referred to as "the article manufacturing method of the present invention").

A third aspect of the present invention is a method for manufacturing a zirconia dental mill blank, which comprises manufacturing a zirconia dental mill blank by the article manufacturing method of the present invention.

In the method for producing a ceramic raw material compound of the present invention (raw material production method of the present invention), the polymerizable monomer (B) is used as an organic binder, so it can be dissolved in an organic solvent (C) and sintered. By a simple method of mixing with the ceramic raw material inorganic powder (A) and then removing the organic solvent (C), it is possible to obtain a compound in which the two are uniformly combined. Therefore, the raw material compound can be produced without using expensive equipment such as a pressure kneader or screw extruder, and without heating at high temperatures. Moreover, the resulting ceramic raw material compound has good moldability and shape retention after molding, similar to compounds using conventional organic resin binders. Further, the compound can be obtained as a powder or granule that is easy to handle and can be applied to molding methods such as injection molding, press molding, and cast molding that are suitable for mass production.

Therefore, the method for manufacturing a ceramic article of the present invention (the article manufacturing method of the present invention) using the ceramic raw material compound obtained by the raw material manufacturing method of the present invention requires heating and mixing using the expensive equipment described above in preparing the compound. It can be said that this method is suitable for manufacturing ceramic articles on a scale where there is no cost advantage in adopting the smelting method.

The ceramic raw material compound produced by the raw material manufacturing method of the present invention includes 100 parts by mass of sinterable ceramic raw material inorganic powder (A) and a polymerizable monomer (B) consisting of an organic compound having a polymerizable group in the molecule. ): 1 part by mass or more and less than 25 parts by mass. Here, the polymerizable monomer (B) functions as an organic binder. As mentioned above, in conventional ceramic raw material compounds, the organic binder softens or lowers the viscosity when heated and exhibits good moldability, and when the temperature returns to room temperature after molding, it hardens or increases the viscosity and maintains a good shape. It is common to use a high molecular weight "organic resin" that exhibits retention properties. On the other hand, although the polymerizable monomer (B) used in the present invention has a low molecular weight, a polymerization initiator is added at the time of molding as in the method described in Patent Document 3. It has good moldability and shape retention after molding even without performing a polymerization and curing step. The reason for this is not necessarily clear, but it is presumed that some of the monomers spontaneously polymerize due to vacuum operations, heating operations at relatively low temperatures, and pressurization operations during the solvent removal process and molding process. ing.

1. Method for producing ceramic raw material compound of the present invention (raw material production method of the present invention)
In the raw material manufacturing method of the present invention, the polymerizable monomer (B) is added to the organic solvent (C) in an amount of 1 part by mass or more and less than 25 parts by mass with respect to 100 parts by mass of the ceramic raw material inorganic powder (A). A slurry in which the ceramic inorganic powder (A) is dispersed in the monomer solution (D) is prepared by mixing the dissolved monomer solution (D) and 100 parts by mass of the ceramic inorganic powder (A). It is characterized by comprising a slurry forming step, and a solvent removal step of removing the organic solvent (C) from the slurry obtained in the slurry forming step.

First, various raw materials used in the raw material manufacturing method of the present invention will be explained.
In this specification, unless otherwise specified, the notation "x to y" using numerical values x and y means "more than or equal to x and less than or equal to y." In such a notation, when a unit is attached only to the numerical value y, the unit shall also be applied to the numerical value x. Further, in this specification, the term "(meth)acrylic" means both "acrylic" and "methacrylic".

1-1. Ceramic raw material inorganic powder (A)
The ceramic raw material inorganic powder (A) is not particularly limited as long as it is a sinterable ceramic powder, and oxide ceramic powder and non-oxide ceramic powder can be used. Specific examples of oxide ceramics include zirconia, alumina, silica, titania, magnesia, silica zirconia, barium titanate, lead zirconate titanate, and lithium disilicate. Examples include zirconium carbide, silicon carbide, aluminum nitride, silicon nitride, and boron nitride. Among these, from the viewpoint of strength etc., it is preferable to use powders of zirconia, alumina, silica, and silica-zirconia. These inorganic powders may be used as a mixture of two or more kinds of inorganic powders, for example, a mixed powder of zirconia and alumina, a mixed powder of zirconia and silica, etc. may be used. When used as a ceramic raw material compound for dental ceramic products such as ceramic mill blanks for dental processing, ceramic raw material inorganic powder containing zirconia powder as the main component is used from the viewpoint of color tone, strength, and toughness. It is preferable. Here, the main component refers to 80 parts by weight or more when the weight of the entire ceramic raw material inorganic powder is 100 parts by weight.

As the ceramic raw material inorganic powder, one having an average crystallite diameter of 0.001 μm to 50 μm is preferable because it is easy to handle, difficult to cause crystal phase transformation, and grain growth does not progress too much due to sintering. used for. It is more preferable to use powder having an average crystallite diameter of 0.003 μm to 20 μm.

Furthermore, the shape (outer shape) of the aggregated particles of the ceramic raw material inorganic powder may be spherical or non-spherical, and the average particle diameter of the aggregated particles is not particularly limited, but from the viewpoint of ease of handling and moldability. The shape is preferably spherical or approximately spherical, and the average particle diameter of the aggregated particles is preferably 5 μm or more and 300 μm or less. Here, the average particle diameter of aggregated particles is a value determined as follows based on observation with a scanning electron microscope (SEM), unless otherwise specified. That is, when the aggregated particles of the ceramic raw material inorganic powder (A) observed by SEM are spherical or approximately spherical, the aggregated particles have the maximum diameter of 100 aggregated particles randomly extracted on the SEM observation screen. It means a value determined by measuring the diameter (Xi) and calculating the average particle diameter of the aggregate based on the following formula 1. In addition, when the particles of the ceramic raw material inorganic powder (A) observed by SEM are amorphous, the maximum diameter is regarded as the aggregate particle diameter (Xi), and as in the case of spherical particles, the aggregate size is determined by formula 1 below. It means a value determined by calculating the average particle diameter.

The ceramic raw material inorganic powder (A) may contain a sintering aid. A sintering aid is an inorganic powder added to promote sintering when manufacturing ceramics. can be used. For example, when the main material is alumina powder, silica, magnesia, calcia, etc. are suitable, and when the main material is zirconia powder, alumina, etc. are suitable. When the ceramic raw material inorganic powder (A) contains a sintering aid, the amount of the sintering aid added is usually 0.005 parts by mass per 100 parts by mass of the sinterable ceramic powder as the main material. ~10 parts by mass.

1-2. Polymerizable monomer (B) (hereinafter also referred to as "monomer")
The polymerizable monomer (monomer) (B) is not particularly limited as long as it is an organic compound having a polymerizable group in the molecule, but from the viewpoint of solubility in organic solvents, its molecular weight is 50 to 1000. , particularly preferably from 100 to 500. Further, from the viewpoint of being easily removed by degreasing and firing steps, it is preferable that the monomer molecule is made of an organic compound in which the only element other than carbon and hydrogen that constitutes the monomer molecule is oxygen and/or nitrogen.

Note that the term "polymerizable group" refers to a functional group that can be polymerized by stimulation with light or heat, and specifically includes radically polymerizable groups such as (meth)acrylic groups and vinyl groups, epoxy groups, and oxetane groups. Examples include cationically polymerizable groups and anionically polymerizable groups.

The polymerizable group in the monomer used in the ceramic raw material compound for ceramic articles for dental use, such as ceramic mill blanks for dental processing, is preferably a (meth)acrylic group for reasons such as safety. Further, from the viewpoint of moldability of the ceramic raw material compound and shape retention after molding, the polymerizable group is preferably a (meth)acrylic group or an epoxy group. Furthermore, from the viewpoint of further enhancing these effects, it is preferable to use monomers that have a plurality of polymerizable groups in the molecule, or one polymerizable group and at least one hydrogen bonding group. . Here, the hydrogen-bonding group means a functional group capable of dipolar interaction within or between molecules, and specifically includes a carboxy group, an amino group, an amide group, a hydroxy group, and the like.

(1) Suitable examples of monomers having multiple polymerizable groups in the molecule include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and urethane monomers having multiple (meth)acrylic groups. Examples include dimethacrylate, bisphenol A diglycidyl methacrylate, 1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane, trimethylolpropane trimethacrylate, and trimethylolethane trimethacrylate.

(2) Examples of those having one polymerizable group and at least one hydrogen-bonding group include glycidyl methacrylate, 4-hydroxybutyl acrylate glycidyl ether, etc., where the polymerizable group is an epoxy group. Examples of those in which the functional group is a (meth)acrylic group include methacrylic acid, 2-methacryloyloxyethyl phthalate, 2-methacryloyloxyethyl hexahydrophthalate, 2-methacryloyloxyethyl succinate, 11-methacryloyloxy-1,1- Examples include undecanedicarboxylic acid and 4-methacryloxyethyl trimellitic acid.

These monomers may be used alone or in combination of two or more.

The content of the monomer in the present invention needs to be 1 part by mass or more and less than 25 parts by mass based on 100 parts by mass of the ceramic raw material inorganic powder (A). If the monomer content is less than 1 part by mass, the improvement in moldability, which is the reason for the addition of the monomer, cannot be obtained. On the other hand, if the content is 25 parts by mass or more, sufficient strength cannot be obtained after degreasing or firing. Not only may the ceramic raw material inorganic powder (A) and the monomer (B) be partially separated during molding. The content of the monomer is preferably 4 to 15 parts by weight. Note that monomer (B) may partially polymerize into relatively low molecular weight polymers or oligomers during the slurry formation process and solvent removal process, but it is not possible to quantify the amount. Since this is difficult, in the present invention, the content of monomer (B) in the ceramic raw material compound is expressed as an amount including these (in other words, the amount of mixed monomers).

1-3. Organic solvent (C)
As the organic solvent (C), any known organic solvent can be used without particular limitation, as long as it dissolves the monomer (B) and has a boiling point lower than the boiling point of the monomer (B) used. From the viewpoint of removability in the solvent removal step, it is preferable to use an organic solvent having a boiling point of 200° C. or lower, particularly 120° C. or lower at normal temperature and normal pressure (25° C., 1 atm).

Examples of organic solvents that can be suitably used include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, diethyl ether, hexane, toluene, dichloromethane, and chloroform.

These solvents may be used alone or in combination of two or more, and when two or more are used in combination, those that are compatible with each other are preferred. Further, water may be included in an amount that does not inhibit dissolution of the monomer.

1-4. Other additives, etc. In addition to the ceramic raw material inorganic powder (A) and the monomer (B), the ceramic raw material powder produced using the raw material manufacturing method of the present invention includes inorganic pigments, organic pigments, Additives such as fluorescent agents, ultraviolet absorbers, and inorganic powder dispersants can be added. In addition, other organic substances may be added as organic components other than the monomer (B) within a range that does not adversely affect the effect. However, from the viewpoint of operability, it is preferable that no polymerization initiator is included. In addition, a polymerization initiator means a compound or a combination of compounds having a function of polymerizing and curing the monomer (B), such as a radical polymerization initiator.

Next, the slurry forming step and the solvent removal step in the raw material production method of the present invention will be explained.

1-5. Slurrying step In the slurrying step, the polymerizable monomer (B) is added to the organic solvent (C) in an amount of 1 part by mass or more and less than 25 parts by mass with respect to 100 parts by mass of the ceramic raw material inorganic powder (A). A monomer solution (D) dissolved in the monomer solution (D) and 100 parts by mass of the ceramic raw material inorganic powder (A) are mixed to form a slurry in which the ceramic inorganic powder (A) is dispersed in the monomer solution (D). Prepare.

The amount of organic solvent (C) used when preparing the monomer solution (D) is an amount that can dissolve the monomer (B) to be used and a ceramic raw material The total amount of powder (A) and monomer (B) is preferably 50 parts by weight or more, more preferably 100 to 3000 parts by weight, particularly 100 to 2000 parts by weight, based on 100 parts by weight.

The slurry can be suitably prepared by mixing the monomer solution (D) and the ceramic raw material inorganic powder (A) in a container and homogenizing the mixture by stirring or the like. As the homogenization method, methods using stirring, shaking, vibration, ultrasonic waves, etc. can be adopted. Furthermore, from the viewpoint of improving dispersibility, a dispersion treatment using a homogenizer, a ball mill, etc. may be performed. In addition, the mixing method is not particularly limited as long as it results in a slurry in which the ceramic inorganic powder (A) is dispersed in the monomer solution (D), but the monomer solution (D) is prepared in advance, This is generally mixed with ceramic raw material inorganic powder (A). At this time, from the viewpoint of homogenizing the slurry in a shorter time, the ceramic raw material inorganic powder (A) is mixed with an organic solvent and/or water in advance to form a slurry, and this is mixed with the monomer solution (D). May be mixed. At this time, the organic solvent may be the same as or different from the organic solvent (C) used in the monomer solution (D), but from the viewpoint of uniform mixing, they must be compatible with each other and It is preferable to use an organic solvent and/or water that does not inhibit the dissolution of the monomer (B).

1-6. Solvent Removal Step In the solvent removal step, the organic solvent (C) is removed from the slurry prepared in the slurry forming step to produce a ceramic raw material compound.

The method for removing the solvent is not particularly limited as long as it is a method that can remove the organic solvent (C) from the slurry, but from the viewpoint of shortening the time required for solvent removal and being able to remove almost all the solvent, vacuum drying method and/or Alternatively, it is preferable to employ a heating drying method. Here, the vacuum drying method is a method in which a solvent is removed under a reduced pressure of, for example, 800 hectopascals or less, and the heat drying method is a method in which a solvent is removed at a temperature higher than room temperature. By heating, the organic solvent can be removed (drying) at a temperature lower than the boiling point of the organic solvent. From the viewpoint of not requiring treatment at high temperatures, even when a heat drying method is employed, it is preferable to dry at a temperature of 100° C. or lower by appropriately using a reduced pressure drying method. By obtaining the solvent removal step, sinterable ceramic raw material inorganic powder (A): 100 parts by mass, and polymerizable monomer (B) consisting of an organic compound having a polymerizable group in the molecule: 1 part by mass A ceramic raw material compound containing less than 25 parts by mass can be obtained.

In the raw material manufacturing method of the present invention, since a low molecular weight polymerizable monomer (B) is used as an organic binder, the ceramic raw material compound can be obtained in the form of powder or granules that are easy to handle. Here, the granular material is a general term for powder and granular material, and specifically, the polymerizable monomer (B ) adhered particles: a1, agglomerated particles where the particles a1 are aggregated: a2, particles where the aggregated particles a2 are disintegrated: a3, and the surface of the aggregated particles constituting the ceramic raw material inorganic powder (A). At least one selected from the group consisting of a4: a4: agglomerated particles to which the polymerizable monomer (B) is attached, a5: a5, agglomerated particles of a4, and a6: a6, agglomerated particles of a5. It means a powder containing one type of particle. Incidentally, even if the inorganic particles are bonded via the polymerizable monomer (B), the bonding force is weak and it can be easily crushed.

Further, the compound obtained by the raw material manufacturing method of the present invention has good moldability and shape retention after molding, similar to compounds using conventional organic resin binders. Therefore, various methods can be applied to mold the ceramic raw material compound. For example, when a thermoplastic resin such as an olefin resin-based organic binder is used as the organic binder, not only is it necessary to knead it using a pressure kneader or screw extruder, but the composite material after kneading is Since it solidifies when cooled, it is generally cut into pellet-like compounds when heated, and in order to mold this, it is necessary to heat it again to impart plasticity. For this reason, molding methods are limited to methods such as injection molding that include such steps. In the injection molding method, not only is the equipment itself expensive, but also energy and labor are required for reheating, so when a resin binder is used, it can be said to be a double burden when compounding. On the other hand, when a powder compound is produced using the raw material manufacturing method of the present invention, it can be molded into the desired shape by simply putting it into a mold and compressing it, reducing the burden during molding. can be reduced.

2. Method for manufacturing ceramic articles of the present invention (method for manufacturing articles of the present invention)
As described above, the article manufacturing method of the present invention includes the step of manufacturing a granular compound using the raw material manufacturing method of the present invention as a manufacturing process of a ceramic raw material compound. In addition to having the advantage of using such a granular compound, it also has the advantage of using such a powder compound, and the heating kneading method using the expensive equipment described above is used for compound preparation It is suitable as a method for manufacturing ceramic articles on a scale where there is no cost benefit in manufacturing ceramic articles, particularly dental ceramic articles such as zirconia dental mill blanks.

Hereinafter, the article manufacturing method of the present invention will be explained in detail.
The article manufacturing method of the present invention includes a step of manufacturing a ceramic raw material compound powder by the raw material manufacturing method of the present invention, and molding the ceramic raw material compound powder obtained in the step to obtain a green body having a predetermined shape. It is characterized by comprising a molding step and a sintering step of sintering the green body obtained in the molding step directly or after degreasing.

2-1. Step of manufacturing ceramic raw material compound powder In this step, 100 parts by mass of sinterable ceramic raw material inorganic powder (A) and an organic compound having a polymerizable group in the molecule are produced by the raw material manufacturing method of the present invention. A ceramic raw material compound containing 1 part by mass or more and less than 25 parts by mass of polymerizable monomer (B) is obtained in the form of powder or granules. Specifically, a powder containing at least one type of particle selected from the group consisting of a1 to a6 is produced. As mentioned above, even if the inorganic particles are bonded via the polymerizable monomer (B), the bonding force is weak and it can be easily disintegrated. By doing so, it is possible to obtain a particle size distribution comparable to that of the ceramic raw material inorganic powder (A) used, although it shifts to a slightly larger size. From the viewpoint of ease of handling and productivity during compression molding, it is preferable to crush the powder as necessary to obtain a particle size distribution comparable to that of the ceramic raw material inorganic powder (A) used.

2-2. Molding Step In the molding step, a compression molded body or a green body of a predetermined shape is obtained using the ceramic raw material compound powder obtained in the above step. At this time, the molding method is not particularly different from the conventional method except that the ceramic raw material compound powder is used as a raw material, and molding is performed by press molding, extrusion molding, injection molding, casting molding, tape molding, or layered manufacturing. A method known as a powder molding method or a green body molding method, such as molding by powder molding, etc., can be used without particular limitation. Further, multi-stage molding may be performed. For example, the ceramic raw material compound powder of the present invention may be uniaxially press-molded and then further subjected to CIP (Cold Isostatic Pressing) treatment. From the viewpoint of being suitable for high-density molding, it is more preferable to use press molding as a molding method, such as uniaxial press molding, biaxial press molding, and HIP (Hot Isostatic Pressing). Examples include molding, CIP (cold isostatic pressing) molding, and the like.

Further, in the molding step, plural types of ceramic raw material compound powder may be laminated and molded.

The shape of the compression molded body or green body obtained in the molding process may be determined as appropriate depending on the shape of the intended ceramic article, but when manufacturing dental mill blanks, it is preferable to use a disc-shaped one (disk type). ), or in the shape of a rectangular parallelepiped or a substantially rectangular parallelepiped (block type).

2-3. Sintering process In the sintering process, the compression molded body or green body obtained in the molding process is heated at a sintering temperature for a certain period of time to obtain a sintered body. Here, sintering (also called firing or sintering) means heating the compression molded body or green body to a temperature below the melting point of the ceramic raw material inorganic powder by holding it at that temperature (or temperature range) for a certain period of time. This means that powder particles are surface-diffused (adhered, fused) to each other and transformed into a polycrystalline body. However, it is not necessary to completely sinter the material, and depending on the application, it may be in the state of a so-called "calcined body" which is fired at a temperature that does not lead to sintering. For example, a zirconia dental mill blank is provided in the state of a so-called zirconia calcined body, and when used, it is often cut into a tooth crown shape using a CAD/CAM system and then subjected to main sintering (for example, according to International Publication WO 2016). /104724 pamphlet). The concept of the ceramic article that is the object of the article manufacturing method of the present invention includes such a calcined body. Further, the above-mentioned sintering temperature refers to a temperature (or temperature range) at which sintering (including calcination) can proceed to a desired degree by maintaining the temperature (or within a certain temperature range) for a certain period of time. From the viewpoint of strength and workability, the temperature is preferably 600°C to 1800°C.

Further, in the article manufacturing method of the present invention, degreasing treatment can also be performed before sintering in the sintering step. Here, the degreasing treatment refers to a treatment for removing by evaporation or decomposition the moisture, solvent, binder, etc. contained in the compression molded body or green body obtained in the molding step. These treatments are usually performed at a temperature of 100° C. or higher and 1100° C. or lower and lower than the sintering temperature.

As the degreasing method, any conventionally known method can be used without particular limitation, and it may be carried out continuously or in multiple stages. Further, in order to efficiently remove organic substances, it is preferable to carry out the process in an air atmosphere containing oxygen. Note that the degreasing treatment is performed using a method that uses the same equipment as the molding step that is the previous step and/or the sintering step that is performed after the degreasing process, such as the SPS (Spark Plasma Sintering) method or the HP (hot press) method. ) method etc., it can also be carried out continuously.

The article manufacturing method of the present invention can be suitably employed as a manufacturing method for zirconia dental mill blanks. Dental zirconia generally contains stabilizers such as yttria, calcia, magnesia, ceria, and erbium oxide, sintering aids such as alumina, and pigments such as iron oxide and cobalt oxide. These may also be included in the zirconia dental mill blank manufactured by the invention. The zirconia dental mill blank preferably manufactured by the article manufacturing method of the present invention is not particularly limited, but from the viewpoint of strength and aesthetics, it is made of partially stabilized zirconia whose main component is tetragonal after sintering. It is preferable that

EXAMPLES Hereinafter, in order to specifically explain the present invention, Examples and Comparative Examples will be given and explained, but the present invention is not limited by these in any way. First, the abbreviations and abbreviations of substances used in the production of samples of each example and comparative example will be explained below.

<Raw materials for ceramic raw compound>
1. Ceramic raw material inorganic powder (A)
- TZ-6Y: Zirconia manufactured by Tosoh Corporation, binder-free product, average primary particle size 40 nm, average particle size of aggregated particles 40 μm, yttria content 6 mol%.

2. Polymerizable monomer (B)
・3G (triethylene glycol dimethacrylate): Manufactured by Shin Nakamura Chemical Co., Ltd., molecular weight = 123, has two methacrylic groups in the molecule. ・UDMA (1,6-bis(methacrylethyloxycarbonylamino)trimethylhexane): Manufactured by Degussa, molecular weight = 471, has two methacrylic groups in the molecule ・CB-1 (2-methacryloyloxyethylphthalic acid): Manufactured by Shin Nakamura Chemical Co., Ltd., molecular weight = 278, has one methacrylic group in the molecule Contains one carboxyl group ・GMA (glycidyl methacrylate): manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., molecular weight = 142, has one methacrylic group and one epoxy group in the molecule OXT-211 ((3-ethyloxetane) 3-yl) methylphenol): manufactured by Toagosei Co., Ltd., molecular weight = 192, has one oxetane group in the molecule. OXE-30 ((3-ethyloxetane 3-yl) methyl methacrylate): Osaka Organic Chemical Industry Co., Ltd. Made by a company, molecular weight = 184, has one methacrylic group and one oxetane group in the molecule.

3. Organic compounds other than polymerizable monomer (B) - 1,5-pentanediol: manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., molecular weight = 104, has two hydroxy groups in the molecule - PEG200 (polyethylene glycol): Fuji Film manufactured by Wako Pure Chemical Industries, Ltd., average molecular weight = 180-220
・PEG400 (polyethylene glycol): Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., average molecular weight = 360-440
・PEG2000000 (polyethylene glycol): Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., molecular weight = approximately 2 million.

4. Organic solvent (C)
・Ethanol: Manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.

Example 1
After weighing 10 g of TZ-6Y and 90 g of ethanol, a TZ-6Y dispersion liquid was obtained by applying ultrasonic waves (desktop ultrasonic cleaner MODEL VS-150, manufactured by As One Corporation, 50 kHz) for 15 minutes. 1.21 g of 3G and 5 g of ethanol were weighed and mixed using a stirrer to obtain a 3G solution. The 3G dispersion was added to the TZ-6Y dispersion and mixed using a stirrer for 2 hours. Thereafter, ethanol was removed by reducing the pressure at room temperature using an evaporator to obtain a ceramic raw material compound powder.

1 g of the obtained ceramic raw material compound powder was uniaxially pressed using a press die with a diameter of 16 mm at a maximum load of 1 t to produce a molded body. A total of four molded bodies were produced and the results were evaluated. The evaluation criteria are shown below.
Evaluation criteria:
◎: All four sheets could be molded without any problem.
○: Three sheets could be molded without any problem.
Δ: Two sheets could be molded without any problem.
×: Only one sheet could be molded, or no sheet could be molded.
The evaluation results are shown in Table 1.

Examples 2-8
A ceramic raw material compound powder was prepared in the same manner as in Example 1, except that the raw material and blended weight of the monomer (B) were changed as shown in Table 1, and the moldability was evaluated in the same manner. The results are shown in Table 1.

Comparative example 1
After weighing and mixing 10 g of TZ-6Y and 90 g of ethanol, a TZ-6Y dispersion liquid was obtained by applying ultrasonic waves for 15 minutes. The TZ-6Y dispersion was mixed using a stirrer for 2 hours. Thereafter, ethanol was removed by reducing the pressure at room temperature using an evaporator to obtain a ceramic raw material compound powder. Thereafter, moldability was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

Comparative examples 2 to 4
Ceramic raw material compound powder was prepared in the same manner as in Example 1, except that the raw material and blended weight of monomer (B) were changed as shown in Table 1, and the moldability was evaluated in the same manner as in Example 1. Results are shown in Table 1.

Comparative example 5
After weighing and mixing 10 g of TZ-6Y and 90 g of ethanol, a TZ-6Y dispersion liquid was obtained by applying ultrasonic waves for 15 minutes. 0.51 g of PEG2,000,000 and 5 g of ethanol were weighed and mixed to obtain a PEG2,000,000 dispersion. The PEG2,000,000 dispersion was added to the TZ-6Y dispersion and mixed using a stirrer for 2 hours. Thereafter, ethanol was removed by reducing the pressure at room temperature using an evaporator to obtain a ceramic raw material compound powder. Thereafter, moldability was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

As shown in Table 1, Examples 1 to 8 exhibited good moldability. On the other hand, in Comparative Example 1, which did not contain an organic compound as a binder, and Comparative Examples 2 to 4, in which a low molecular weight organic compound other than a monomer was added as a binder, the moldability was extremely low. Furthermore, in Comparative Example 5 in which a high molecular weight organic compound other than a monomer was added as a binder, it did not dissolve in a volatile solvent, and as a result, it was not possible to obtain a powder in which the inorganic powder and the binder were uniformly composited. Moldability was extremely low.

Claims (5)

Sinterable ceramic raw material inorganic powder (A): 100 parts by mass, and has a plurality of polymerizable groups in the molecule, or one polymerizable group and at least one hydrogen bonding group, and has a molecular weight of 50 A method for producing a ceramic raw material compound comprising a polymerizable monomer (B) consisting of 1000 or more organic compounds: 1 part by mass or more and less than 25 parts by mass,
A monomer solution (D) in which the polymerizable monomer (B) is dissolved in an organic solvent (C) in an amount of 1 part by mass or more and less than 25 parts by mass with respect to 100 parts by mass of the ceramic raw material inorganic powder (A). and 100 parts by mass of the ceramic raw material inorganic powder (A) to prepare a slurry in which the ceramic inorganic powder (A) is dispersed in the monomer solution (D); a solvent removal step of removing the organic solvent (C) from the slurry obtained in the slurry forming step;
The method for producing the ceramic raw material compound, characterized in that the method comprises: 2. The method of claim 1, wherein the ceramic raw compound is free of polymerization initiators. The method according to claim 1 or 2, wherein the ceramic raw material compound is a granular material. A step of producing ceramic raw material compound powder by the method according to any one of claims 1 to 3 ,
A molding step of molding the ceramic raw material compound powder obtained in the above step to obtain a green body having a predetermined shape, and a sintering step of sintering the green body obtained in the molding step directly or after degreasing treatment. A method for manufacturing a ceramic article, comprising: A method for producing a zirconia dental mill blank, comprising producing a zirconia dental mill blank by the method according to claim 4 .