Ceramic slurry composition for photocurable 3D printing

Abstract

The present invention relates to a ceramic slurry composition for photocurable 3D printing, and more specifically, to a ceramic slurry composition for photocurable 3D printing that allows dental prostheses to exhibit aesthetics similar to natural teeth by using ceramic or glass ceramic powder, and furthermore, enables the production of a low-viscosity slurry containing a high amount of ceramic or glass ceramic powder by including a non-reactive diluent, and the slurry produced in this way is easy to mold using 3D printing, and enables the production of high-quality three-dimensional molded articles during 3D printing.

Description

Technology Field

[0001] The present invention relates to a ceramic slurry composition for photocurable 3D printing, and more specifically, to a ceramic slurry composition for photocurable 3D printing comprising a non-reactive diluent. Background Technology

[0002] Artificial replacements for teeth or dental tissues are called dental prostheses. Materials used for dental prostheses include polymers, metals, alloys, ceramics, and composites; generally, precious metals such as gold, non-precious metal alloys such as nickel-chromium or cobalt-chromium alloys, and ceramics are widely used.

[0003] Recently, as users' expectations regarding aesthetics have risen due to the improvement in living standards, the demand for dental prosthetics made of ceramic materials is increasing compared to conventional metal prosthetics.

[0004] CAD / CAM methods and hot-pressure casting methods are widely used for the fabrication of dental prosthetics using ceramic materials.

[0005] In this regard, Japanese Patent No. 6,758,673 discloses dental ceramic materials such as a dental ceramic laminate used for dental cutting processing using a CAD / CAM system, a dental ceramic temporary sintered body, a dental ceramic sintered body, and a dental prosthesis produced using these materials.

[0006] In the CAD / CAM method, the shape of the dental prosthesis is determined on a computer based on dental data. Subsequently, the dental prosthesis is fabricated by cutting a ceramic block according to the determined shape. This method has the problem that the ceramic block is lost in portions other than the volume of the dental prosthesis. In addition, the CAD / CAM cutting method can only process one ceramic block per piece of equipment, and since the drill blades used to cut the ceramic blocks are expensive, there are problems such as long manufacturing times and high manufacturing costs.

[0007] In addition, Japanese Patent No. 6855121 discloses a wax-patterned surface treatment material used in combination with a phosphate-based investment material used during press molding of dental press ceramics, and a method for manufacturing dental press ceramics using the same.

[0008] The hot-pressure casting method, a press forming method for ceramics, produces dental prostheses by pouring glass ceramic ingots, produced through crystallization heat treatment, into a mold formed by the lost-wax method while in a heated state. This method consumes auxiliary materials such as plaster and wax, and is less efficient due to the additional processes of plaster mixing, burn-out, and hot-pressing. Furthermore, there is a problem in that all parts of the glass ceramic ingot used, excluding the volume of the ceramic prosthesis, are lost.

[0009] Recently, 3D printing technology is being adopted as an alternative to solve the problems of the aforementioned dental prosthesis fabrication methods, and research seeking to apply photocurable 3D printing technology, which has high printing precision, to the molding of ceramic structures is receiving particular attention.

[0010] Photocurable 3D printing technology is a technology for forming three-dimensional ceramic molded bodies by selectively curing a liquid ceramic slurry, which is a composite of ceramic or glass ceramic powder and a photocurable resin, using a beam such as UV. In order to form high-quality ceramic structures, there is a need for the development of optimal slurry composition technology to produce a highly filled photocurable ceramic slurry that has a high ceramic content and flowability suitable for 3D printing. Prior art literature

[0011] Japanese Patent No. 6,758,673 (Registration Date: Sep. 4, 2020) “Dental ceramic material” Japanese Patent No. 6,855,121 (Registration Date: Mar. 19, 2021) “Wax pattern surface treatment material used in combination with phosphate-based investment material and method for producing dental press ceramic using the same” The problem to be solved

[0012] The present invention aims to solve the problems according to the prior art described above. The present invention provides a ceramic slurry composition for photocurable 3D printing that allows a dental prosthesis to exhibit aesthetics similar to natural teeth by using ceramic or glass ceramic powder, and furthermore, enables the production of a low-viscosity slurry containing a high amount of ceramic or glass ceramic powder by including a non-reactive diluent. means of solving the problem

[0013] As a technical means to achieve the aforementioned technical problem, one aspect of the present invention provides a ceramic slurry composition for photocurable 3D printing comprising: ceramic or glass ceramic powder; an acrylate-based monomer; a photoinitiator; a non-reactive diluent; and a dispersant.

[0014] The above photocurable 3D printing ceramic slurry composition may comprise 40 to 85 weight% of the ceramic or glass ceramic powder; 5 to 30 weight% of the acrylate-based monomer; 0.04 to 1 weight% of the photoinitiator; 3 to 13 weight% of the non-reactive diluent; and 1 to 9 weight% of the dispersant.

[0015] The above-described ceramic slurry composition for photocurable 3D printing may contain 40 to 85 weight percent of the ceramic or glass ceramic powder by including the above-described non-reactive diluent, and may be capable of producing a photocurable ceramic 3D printed structure having a biaxial strength of 200 MPa or more.

[0016] The above ceramic or glass ceramic powder is zirconia (ZrO2), alumina (Al2O3), zirconia-alumina composite (ZrO2-Al2O3), yttria (Y2O3), titania (TiO2), silica (SiO2), magnesia (MgO), silicon nitride (Si3N4), titanium nitride (TiN), aluminum nitride (AlN), silicon carbide (SiC), boron carbide (Boron Carbide, B4C), spinel (MgAl2O4), mullite (3Al2O3·2SiO2), tantalum carbide (Tantalum Carbide, TaC), boron nitride (B4C), zinc oxide (ZnO), zinc sulfate (ZnSO4), barium sulfate (BaSO4), magnesium fluoride (MgF2), thorium fluoride (ThF4), yttrium fluoride (YF3), It may include one or more selected from the group consisting of crystallized glass, TCP (Tricalcium phosphate), OCP (Octacalcium phosphate), FHA (Fluoridated hydroxyapatite), BCP (Biphasic calcium phosphate), calcium sulfate (CaSO4), calcium silicate, bioglass, feldspar, lithium disilicate, Lucite, hydroxyapatite (HA), and combinations thereof.

[0017] The above acrylate-based monomer may include one or more selected from the group consisting of monofunctional monomers, difunctional monomers, polyfunctional monomers, oligomer monomers, and combinations thereof.

[0018] The above non-reactive diluents are Diethyl hexyl cyclohexane, Butyl glycidyl ether, Ethylene glycol digylcidyl ether, 2-ethyl hexyl phthalate, Di-isononyl phthalate, Di-butyl phthalate, Tri-2-ethyl hexyl trimellitate, Di-2-ethyl hexyl adipate, Lauryl glycidyl ether, 1,4-Butanediol diglycidyl ether, and Dioctyl terephthalate. It may include one or more selected from a group consisting of combinations thereof.

[0019] The above-described ceramic slurry composition for photocurable 3D printing may further include one or more additives selected from the group consisting of light-absorbing dyes, light-absorbing agents, silane coupling agents, and combinations thereof.

[0020] The light-absorbing dye may include one or more selected from the group consisting of anthraquinone, diazo, isoindolinone, mono azo salts, benzimidazolone, diketopyrrolopyrrole, BONA lake, quinacridone, and combinations thereof.

[0021] The above light absorber is 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine(2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine), 2-[4-[(2-hydroxy-3-(2-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine(2-[4-[(2-hydroxy-3-(2-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine), It may include one or more selected from the group consisting of Bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, Methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, and combinations thereof.

[0022] The slurry prepared from the above photocurable 3D printing ceramic slurry composition may have a viscosity in the range of 350 to 40,000 cP. Effects of the invention

[0023] The ceramic slurry composition for photocurable 3D printing according to the present invention enables the production of three-dimensional molded articles that exhibit superior aesthetics compared to metals by including ceramic or glass ceramic powder.

[0024] In addition, the ceramic slurry composition for photocurable 3D printing according to the present invention includes a non-reactive diluent, thereby enabling the production of a low-viscosity slurry containing a high amount of ceramic or glass ceramic powder, and the slurry produced in this way is easy to mold using 3D printing, and can produce a high-quality three-dimensional molded article when 3D printing. Brief explanation of the drawing

[0025] Figure 1 is a graph showing the viscosity of different types of non-reactive diluents in a ceramic slurry composition for 3D printing that includes lithium disilicate and 3% by weight of a non-reactive diluent, in one embodiment of the present invention. FIG. 2 is a graph showing the viscosity of different types of non-reactive diluents in a ceramic slurry composition for 3D printing that includes lithium disilicate and 9% by weight of a non-reactive diluent, in one embodiment of the present invention. FIG. 3 is a graph showing the viscosity of different types of non-reactive diluents in a ceramic slurry composition for 3D printing that includes lithium disilicate and 13% by weight of a non-reactive diluent, in one embodiment of the present invention. FIG. 4 is a graph showing the viscosity of a ceramic slurry composition for 3D printing according to the type of non-reactive diluent, comprising lithium disilicate and 17 weight% of a non-reactive diluent in one embodiment of the present invention. FIG. 5 is a graph showing the viscosity of a ceramic slurry composition for 3D printing containing zirconia and 3% by weight of a non-reactive diluent according to the type of non-reactive diluent in one embodiment of the present invention. FIG. 6 is a graph showing the viscosity of a ceramic slurry composition for 3D printing containing zirconia and 9% by weight of a non-reactive diluent according to the type of non-reactive diluent in one embodiment of the present invention. FIG. 7 is a graph showing the viscosity of a ceramic slurry composition for 3D printing containing zirconia and 13% by weight of a non-reactive diluent according to the type of non-reactive diluent in one embodiment of the present invention. FIG. 8 is a graph showing the viscosity of a ceramic slurry composition for 3D printing containing zirconia and 17% by weight of a non-reactive diluent according to the type of non-reactive diluent in one embodiment of the present invention. FIG. 9 is a photograph and graph showing the viscosity and disc specimen output results of a ceramic slurry composition for 3D printing according to the content of polyethylene glycol (non-reactive diluent) and containing lithium disilicate in one embodiment of the present invention. FIG. 10 is a photograph and graph showing the viscosity and disc specimen output results of a ceramic slurry composition for 3D printing according to the content of polypropylene glycol (non-reactive diluent) and containing lithium disilicate in one embodiment of the present invention. FIG. 11 is a photograph and graph showing the viscosity and disc specimen output results of a ceramic slurry composition for 3D printing according to the content of diethylhexyl cyclohexane (non-reactive diluent) and containing lithium disilicate in one embodiment of the present invention. FIG. 12 is a photograph and graph showing the viscosity and disc specimen output results of a ceramic slurry composition for 3D printing according to the content of dioctyl terephthalate (non-reactive diluent) and containing lithium disilicate in one embodiment of the present invention. FIG. 13 is a photograph and graph showing the viscosity and disc specimen output results of a ceramic slurry composition for 3D printing according to the content of 1,4-butanediol glycityl ether (non-reactive diluent) and containing lithium disilicate in one embodiment of the present invention. FIG. 14 is a photograph and graph showing the viscosity and disc specimen output results of a ceramic slurry composition for 3D printing according to the content of 2-butoxyethanol (non-reactive diluent) and containing lithium disilicate in one embodiment of the present invention. FIG. 15 is a graph showing the viscosity of a ceramic slurry composition for 3D printing according to the content of polypropylene glycol (non-reactive diluent) and containing zirconia in one embodiment of the present invention. FIG. 16 is a graph showing the viscosity of a ceramic slurry composition for 3D printing according to the content of diethylhexyl cyclohexane (non-reactive diluent) and containing zirconia in one embodiment of the present invention. FIG. 17 is a graph showing the viscosity of a ceramic slurry composition for 3D printing according to the content of dioctyl terephthalate (non-reactive diluent) and containing zirconia in one embodiment of the present invention. FIG. 18 is a graph showing the viscosity of a ceramic slurry composition for 3D printing according to the content of 1,4-butanediol diglycidyl ether (non-reactive diluent), which includes zirconia, in one embodiment of the present invention. FIG. 19 is a graph showing the viscosity of a ceramic slurry composition for 3D printing according to the content of 2-butoxyethanol (non-reactive diluent), which includes zirconia, in one embodiment of the present invention. FIG. 20 is a graph showing the photocuring depth measured by irradiating light for 3 seconds to confirm the photocuring depth when 9% by weight of each type of non-reactive diluent is included in one embodiment of the present invention. FIG. 21 is a graph showing the results of measuring the biaxial strength of ceramic structures containing lithium disilicate and using 3 wt% of different non-reactive diluents in one embodiment of the present invention, and a photograph showing the scanning electron microscope (SEM) results of each ceramic structure. FIG. 22 is a graph showing the results of measuring the flexural strength of ceramic structures containing zirconia and using 3% by weight of different non-reactive diluents in one embodiment of the present invention, and a photograph showing the scanning electron microscope (SEM) results of each ceramic structure. FIG. 23 is a graph and scanning electron microscope (SEM) image showing the results of measuring the biaxial strength of photocurable ceramic 3D printed structures prepared using Examples 1 to 3 and Comparative Example 1, in which lithium disilicate was used as the ceramic powder and 1,4-butanediol diglycidyl ether was used as the non-reactive diluent, in one embodiment of the present invention. FIG. 24 is a graph showing the results of measuring the biaxial strength of ceramic structures using different amounts of ceramic powder, wherein the non-reactive diluent content is 9 wt% in one embodiment of the present invention, and a photograph showing the scanning electron microscope (SEM) results of each ceramic structure. Specific details for implementing the invention

[0026] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0027] The terms used in this invention are used merely to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the description of the invention, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0028] Unless otherwise defined in this specification, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which the present invention pertains.

[0029] Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this specification.

[0030] In interpreting the components, they shall be interpreted as including a margin of error even without separate explicit notation. In particular, when terms of degree such as "approximately" or "substantially" are used, they may be interpreted as referring to the value or a value close to it when a tolerance for the inherent manufacturing and material is presented.

[0031] In the case of an explanation of a temporal relationship, for example, when the temporal sequence is explained using 'after', 'following', 'next', 'before', etc., it includes cases where the sequence is not continuous unless 'immediately' or 'directly' is used.

[0032] Hereinafter, the technical configuration of the present invention will be described in detail with reference to preferred embodiments.

[0033] The present invention provides a ceramic slurry composition for photocurable 3D printing comprising: ceramic or glass ceramic powder; an acrylate-based monomer; a photoinitiator; a non-reactive diluent; and a dispersant.

[0034] Specifically, the ceramic slurry composition for photocurable 3D printing may comprise 40 to 85 weight% of the ceramic or glass ceramic powder; 5 to 30 weight% of the acrylate-based monomer; 0.04 to 1 weight% of the photoinitiator; 3 to 13 weight% of the non-reactive diluent; and 1 to 9 weight% of the dispersant.

[0035] The ceramic or glass ceramic powder is configured to control the viscosity of the ceramic slurry composition for photocurable 3D printing and the strength of the molded body, and may comprise 40 to 85 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing. Specifically, the ceramic or glass ceramic powder may comprise 40 to 45 weight%, 45 to 50 weight%, 50 to 55 weight%, 60 to 65 weight%, 65 to 70 weight%, 70 to 75 weight%, 75 to 80 weight%, or 80 to 85 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing.

[0036] If the content of the ceramic or glass ceramic powder is less than 40% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing, the quality of the 3D object printed by the 3D printer may deteriorate due to defects such as cracking or degradation of physical properties during the heat treatment (degreasing process or sintering process). In addition, due to the low content of ceramic or glass ceramic powder, it may be impossible to manufacture small-sized 3D objects, which may result in a problem where the dimensions of the 3D objects that can be produced are limited. Furthermore, if the content of the ceramic or glass ceramic powder exceeds 85% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing, the viscosity of the slurry prepared with the ceramic slurry composition for photocurable 3D printing increases, resulting in a viscosity unsuitable for 3D printing. Consequently, the usability of the 3D printer decreases, which may lead to an increase in the defect rate due to 3D printing failure.

[0037] Accordingly, it is preferable that the ceramic or glass ceramic powder comprises 40 to 85 weight percent based on the total weight of the photocurable 3D printing ceramic slurry composition.

[0038] The above-described ceramic slurry composition for photocurable 3D printing may comprise 40 to 85 weight percent of the ceramic or glass ceramic powder by including the above-described non-reactive diluent, and may be capable of producing a photocurable ceramic 3D printed structure having a biaxial strength (or flexural strength) of 200 MPa or more. For example, the biaxial strength may be 200 to 600 MPa, 200 to 500 MPa, 200 to 400 MPa, 300 to 600 MPa, 300 to 500 MPa, or 300 to 400 MPa.

[0039] The ceramic may include an inorganic material having a crystalline structure and generally manufactured from the corresponding powder, and the glass ceramic may include a material manufactured by controlled crystallization from amorphous glass, particularly silicate glass, in which a glass phase and one or more crystalline phases exist simultaneously in a solid.

[0040] The above ceramic or glass ceramic powder is zirconia (ZrO2), alumina (Al2O3), zirconia-alumina composite (ZrO2-Al2O3), yttria (Y2O3), titania (TiO2), silica (SiO2), magnesia (MgO), silicon nitride (Si3N4), titanium nitride (TiN), aluminum nitride (AlN), silicon carbide (SiC), boron carbide (Boron Carbide, B4C), spinel (MgAl2O4), mullite (3Al2O3·2SiO2), tantalum carbide (Tantalum Carbide, TaC), boron nitride (B4C), zinc oxide (ZnO), zinc sulfate (ZnSO4), barium sulfate (BaSO4), magnesium fluoride (MgF2), thorium fluoride (ThF4), yttrium fluoride (YF3), It may include one or more selected from the group consisting of crystallized glass, TCP (Tricalcium phosphate), OCP (Octacalcium phosphate), FHA (Fluoridated hydroxyapatite), BCP (Biphasic calcium phosphate), calcium sulfate (CaSO4), calcium silicate, bioglass, feldspar, lithium disilicate, Lucite, hydroxyapatite (HA), and combinations thereof.

[0041] For example, the glass ceramic powder may be a lithium disilicate glass ceramic powder.

[0042] The above lithium disilicate glass ceramic powder may include one or more selected from the group consisting of a base material, a nucleation aid, a coloring agent, a fluidity additive, a fluorescent material, a clarifying agent (adsorbent), and combinations thereof.

[0043] The base material of the above lithium disilicate glass ceramic powder is configured to act as a main component for the formation of lithium disilicate glass ceramic crystals, and the base material may include one or more selected from the group consisting of silicon dioxide (SiO2), lithium carbonate (LiCO3), lithium oxide (Li2O), potassium nitrate (KNO3), potassium oxide (K2O), aluminum oxide (Al2O3), zinc oxide (ZnO), and combinations thereof.

[0044] The nucleation aid of the above lithium disilicate glass ceramic powder is configured to act as a nucleating agent for the crystallization of lithium disilicate glass, and the nucleation aid may include one or more selected from the group consisting of ammonium phosphate monobasic (NH4H2PO4) or phosphorus pentoxide (P2O5), zirconium oxide (ZrO2), titanium dioxide (TiO2), and combinations thereof.

[0045] The coloring agent of the above lithium disilicate glass ceramic powder is configured to impart a color identical or similar to that of teeth, and the coloring agent may include one or more selected from the group consisting of vanadium pentoxide (V2O5) which exhibits an orange color, cerium oxide (CeO2) which exhibits a yellow color, erbium oxide (Er2O3) which exhibits a pink color, magnesium oxide (MgO) which exhibits a milky white color, and combinations thereof.

[0046] The fluidity additive of the lithium disilicate glass ceramic powder is a component added to enhance the improved processability and storage stability of the lithium disilicate glass ceramic powder compositions, and the fluidity additive may include lanthanum oxide (La2O3).

[0047] The fluorescent material of the above lithium disilicate glass ceramic powder is configured to impart gloss and fluorescence to the tooth restoration to make the appearance of the tooth restoration manufactured using the above lithium disilicate glass ceramic powder more natural, and the fluorescent material may include terbium oxide (Tb4O7).

[0048] The clarifying agent (adsorbent) of the above lithium disilicate glass ceramic powder is configured to generate gas by vaporizing at high temperatures when the lithium disilicate glass is melted, or to reduce the viscosity of the lithium disilicate glass melt to promote the removal of bubbles within the melt, and the clarifying agent (adsorbent) may include antimony trioxide (Sb2O3).

[0049] The above method for manufacturing lithium disilicate glass ceramic powder may include the following steps:

[0050] (S1) A step of weighing the raw materials according to the composition of the lithium disilicate glass ceramic powder using a precision balance and placing them in a mixing container;

[0051] (S2) A step of dry mixing the raw materials contained in the mixing container using a ball mill without solvent (or water) and ceramic balls;

[0052] (S3) A step of placing the above-mentioned mixed raw materials into a platinum (Pt) crucible and performing a first melting in an elevator furnace under an atmospheric atmosphere;

[0053] (S4) A step of pouring the glass (lithium disilicate glass) liquefied through the above first melting step into distilled water contained in a stainless or ceramic tray to perform first rapid cooling (overcooling);

[0054] (S5) A step of roughly crushing the glass (lithium disilicate glass) that has been supercooled through the above first rapid cooling step using a crusher;

[0055] (S6) A step of placing the above-mentioned first crushed glass (lithium disilicate glass) into a platinum (Pt) crucible and melting it a second time in an elevator furnace in an atmospheric atmosphere;

[0056] (S7) A step of pouring the glass (lithium disilicate glass) liquefied through the above secondary melting step into distilled water contained in a stainless or ceramic tray to perform secondary rapid cooling (overcooling);

[0057] (S8) A step of roughly crushing the glass (lithium disilicate glass) that has been supercooled through the above second rapid cooling step using a crusher;

[0058] (S9) A step of removing moisture by placing the above secondary crushed glass (lithium disilicate glass) into an oven;

[0059] (S10) A step of placing the above-mentioned moisture-removed glass (lithium disilicate glass) containing a solvent (or water) and ceramic balls into a ball mill facility and wet-grinding it; and,

[0060] (S11) A step of obtaining glass powder (lithium disilicate glass ceramic powder) by micronizing the glass (lithium disilicate glass) that has undergone the above wet grinding using grinding equipment such as an attrition mill, a nano-set mill, or a Zet mill.

[0061] The above acrylate-based monomer is configured to contain at least one organic functional group capable of photocuring, and may comprise 5 to 30 weight% based on the total weight of the ceramic slurry composition for photocurable 3D printing. Specifically, the acrylate-based monomer may comprise 5 to 10 weight%, 10 to 15 weight%, 15 to 20 weight%, 20 to 25 weight%, or 25 to 30 weight% based on the total weight of the ceramic slurry composition for photocurable 3D printing.

[0062] If the content of the acrylate-based monomer is less than 5% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing, photocuring is not properly carried out, making it difficult to form the desired polymer. Additionally, there is a problem in that the viscosity of the slurry prepared with the ceramic slurry for photocurable 3D printing increases, making it difficult to mix ceramic or glass ceramic powders. Furthermore, if the content of the acrylate-based monomer exceeds 30% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing, the shrinkage rate after sintering of the slurry prepared with the ceramic slurry composition for photocurable 3D printing increases, which may cause cracks in the 3D molded body or make it difficult to maintain its shape.

[0063] Accordingly, it is preferable that the acrylate-based monomer comprises 5 to 30 weight percent based on the total weight of the photocurable 3D printing ceramic slurry composition.

[0064] The above acrylate-based monomer may include one or more selected from the group consisting of monofunctional monomers, difunctional monomers, polyfunctional monomers, oligomer monomers, and combinations thereof.

[0065] The above monofunctional monomers are Caprolactone Acrylate, Isooctyl Acrylate, 2-(Cyclohexane-1,2-dicarboximide) ethyl Acrylate, Cyclic trimethylolpropane formal Acrylate, Phenoxybenzyl Acrylate, Isobornyl Acrylate, o-phenylphenol EO Acrylate, o-phenylphenol (EO)2 Acrylate, Benzyl Acrylate, Lauryl Acrylate, Isodecyl Acrylate, and Phenol (EO) Acrylate. Acrylate), Phenol (EO)2-Acrylate, Tetrahydrofurfuryl Acrylate, Ethoxy ethoxy ethyl Acrylate, Stearyl Acrylate, Isobornyl Methacrylate, Benzyl Methacrylate, Lauryl / Tridecyl Methacrylate, Phenoxy Methacrylate, Tetrahydrofurfuryl Methacrylate, Stearyl Methacrylate,It may include one or more selected from the group consisting of methoxy PEG600 methacrylate and combinations thereof.

[0066] The above difunctional monomer is 1,6-Hexanediol Diacrylate, 1,6-Hexanediol (EO) n Diacrylate(1,6-hexanediol(EO)) n Diacrylate), 1,10-Decanediol Diacrylate, Butanediol Diacrylate, Neopentylglycol (PO)2Diacrylate, Tripropylene glycol Diacrylate, Dipropylene glycol Diacrylate, Triethylene glycol Diacrylate, Bisphenol A (EO)4Diacrylate, Bisphenol A (EO)3Diacrylate, Bisphenol A (EO) 10 Diacrylate (Bisphenol A (EO) 10 Diacrylate), Bisphenol A (EO) 20 Diacrylate (Bisphenol A (EO) 20Diacrylate), ricyclodecane dimethanol diacrylate, Tetraethylene glycol diacrylate, Polyethylene glycol 400 diacrylate, Polyethylene glycol 200 diacrylate, Polyethylene glycol 300 diacrylate, Polyethylene glycol 600 diacrylate, Polypropylene glycol 400 diacrylate, 1,6-Hexanediol dimethacrylate, 1,4-Butanediol dimethacrylate, Neopentyl glycol Dimethacrylate, Ethylene glycol Dimethacrylate, Diethylene glycol Dimethacrylate, Triethylene glycol Dimethacrylate, Tetraethylene glycol Dimethacrylate, Bisphenol A (EO)₄ Dimethacrylate, Bisphenol A (EO)₃ Dimethacrylate, Bisphenol A (EO)₃ 10 Dimethacrylate (Bisphenol A (EO) 10 Dimethacrylate), Bisphenol A (EO) 30Dimethacrylate (Bisphenol A (EO) 30 It may include one or more selected from the group consisting of dimethacrylate), 1,3-Butylene glycol dimethacrylate, Polyethylene glycol 400 dimethacrylate, Polyethylene glycol 200 dimethacrylate, and combinations thereof.

[0067] The above polyfunctional monomers are Trimethylolpropane Triacrylate, Trimethylolpropane (EO)3Triacrylate, Trimethylolpropane (EO)6Triacrylate, Glycerine (PO)3Triacrylate, Pentaerythritol Triacrylate, Trimethylolpropane (PO)3Triacrylate, Tris(2-hydroxyethyl)isocyanurate Triacrylate, Trimethylolpropane Trimethacrylate, and Ditrimethylolpropane Tetraacrylate (Ditrimethylolpropane tetraacrylate), Pentaerythritol Tetraacrylate (Pentaerythritol tetraacrylate), Pentaerythritol (EO) n Tetraacrylate (Pentaerythritol (EO)) nTetraacrylate), Dipentaerythritol Pentaacrylate, Dipentaerythritol Hexaacrylate, Dipentaerythritol (EO) 24 Hexaacrylate (Dipentaerythritol (EO) 24 It may include one or more selected from the group consisting of hexaacrylates and combinations thereof.

[0068] The above oligomer monomer may include one or more selected from the group consisting of aliphatic urethane acrylates, aromatic urethane acrylates, urethane methacrylate, epoxy acrylate (Bisphenol A type), epoxy methacrylate (Bisphenol A type), epoxy acrylates (Novolac type), epoxy acrylates (Modified type), polyester acrylates, silicone acrylates, melamine acrylate, butadiene acrylate, and combinations thereof.

[0069] The above oligomer monomer has the effect of maintaining the shape of the printed object when layering and curing are performed using a 3D printer, and increasing workability during sintering.

[0070] The above photoinitiator is configured to absorb ultraviolet rays to generate radicals or cations and initiate photopolymerization, and may be included in an amount of 0.04 to 1 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing. Specifically, the above photoinitiator may be included in an amount of 0.04 to 0.2 weight%, 0.15 to 0.3 weight%, 0.25 to 0.4 weight%, 0.35 to 0.5 weight%, 0.45 to 0.6 weight%, 0.55 to 0.7 weight%, 0.65 to 0.8 weight%, 0.75 to 0.9 weight%, or 0.85 to 1 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing.

[0071] The above photoinitiator is 2-(Dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholinyl)phenyl]-1-butanone, Benzyl dimethyl ketal, Hydroxy cyclohexyl phenyl ketone, Hydroxy dimethyl acetophenone, Methyl-[4-methylthiophenyl]-2-morpholine propanone, 2,4-Diethylthioxanthone Ethyl-4-dimethylaminobenzoate, It may include one or more selected from the group consisting of 4-Chlorobenzophenone, Benzophenone, 4-Phenylbenzophenone, 2,4,6-Trimethylbenzoyl-diphenyl phosphine oxide, Ethyl phenyl(2,4,6-trimethylbenzoyl)phosphinate, Methyl benzoylformate, Bis-(2,4,6-Trimethylbenzoyl)-phenylphosphine oxide, 2-Isopropylthioxanthone, and combinations thereof.

[0072] The above-mentioned non-reactive diluent is configured to control the viscosity of a slurry prepared with the above-mentioned ceramic slurry composition for photocurable 3D printing, and may comprise 3 to 13 weight% relative to the total weight of the above-mentioned ceramic slurry composition for photocurable 3D printing. Specifically, the above-mentioned non-reactive diluent may comprise 3 to 9 weight%, 5 to 10 weight%, or 8 to 13 weight% relative to the total weight of the above-mentioned ceramic slurry composition for photocurable 3D printing.

[0073] If the content of the non-reactive diluent is less than 3% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing, the viscosity of the slurry prepared with the ceramic slurry composition for photocurable 3D printing becomes too high to be suitable for application to a 3D printer, which may cause 3D printing failure or increase the defect rate of the three-dimensional object printed through the 3D printer. In addition, if the content of the non-reactive diluent exceeds 13% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing, insufficient photocuring may occur due to the excessive amount of non-reactive diluent, which may result in a decrease in the strength of the three-dimensional object printed through the 3D printer.

[0074] Accordingly, it is preferable that the above-mentioned non-reactive diluent comprises 3 to 13 weight percent based on the total weight of the above-mentioned ceramic slurry composition for photocurable 3D printing.

[0075] The slurry prepared with the above 3D printing ceramic slurry composition may have a lower viscosity by including the above non-reactive diluent. Accordingly, the slurry may contain a high content of ceramic or glass ceramic powder, and the photocurable 3D printing ceramic slurry composition can produce a high-strength ceramic three-dimensional object due to the high content of ceramic or glass ceramic powder.

[0076] The above non-reactive diluents are Diethyl hexyl cyclohexane, Butyl glycidyl ether, Ethylene glycol digylcidyl ether, 2-ethyl hexyl phthalate, Di-isononyl phthalate, Di-butyl phthalate, Tri-2-ethyl hexyl trimellitate, Di-2-ethyl hexyl adipate, Lauryl glycidyl ether, 1,4-Butanediol diglycidyl ether, and Dioctyl terephthalate. It may include one or more selected from a group consisting of combinations thereof.

[0077] The slurry prepared from the ceramic slurry composition for photocurable 3D printing containing the above-mentioned non-reactive diluent may have a viscosity range of 350 to 40,000 cP.

[0078] If the viscosity of the slurry used for 3D printing is too high, the slurry cannot be printed with a 3D printer; therefore, the viscosity of the slurry prepared with the photocurable 3D printing ceramic slurry composition is suitable in a viscosity range of 350 to 40000 cP, 350 to 30000 cP, 350 to 20000, 350 to 10000 cP, 350 to 5000 cP, 350 to 3000 cP, 1000 to 40000 cP, 5000 to 40000 cP, 10000 to 30000 cP, 10000 to 20000 cP, or 8000 to 15000 cP. The viscosity of the slurry may be the viscosity measured at 50 rpm at room temperature.

[0079] Therefore, the above slurry is easy to use in a 3D printer and has excellent slurry moldability, so it can exhibit high 3D printer output precision.

[0080] The above-mentioned dispersant may be included in an amount of 1 to 9 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing, as a component for increasing the content of ceramic or glass ceramic powder (solid content) of the ceramic slurry composition for photocurable 3D printing and improving the problem of reduced fluidity of the slurry prepared with the ceramic slurry composition for photocurable 3D printing. Specifically, the above-mentioned dispersant may be included in an amount of 1 to 2 weight%, 2 to 3 weight%, 3 to 4 weight%, 4 to 5 weight%, 5 to 6 weight%, 6 to 7 weight%, 7 to 8 weight%, or 8 to 9 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing.

[0081] The above dispersant is a phosphoric acid ester, an alkylol ammonium salt of a copolymer with acidic groups, polyisobutylene succinimide, a solution of a modified urea, poly(oxy-1,2-ethanediyl), a-hydro-ω-hydroxy-, mono-C13-15-alkyl ethers, succinates, polyamine amide salt, an alkylammonium salt of a high molecular weight copolymer, polyacrylic acid (PAA), ammonium polyacrylate, and polymethacrylic It may include one or more selected from the group consisting of acid (polymethacrylic acid, PMAA), sodium polyacrylate (sodium polyacrylate), sodium naphthalene sulfonate (sodium naphthalene sulfonate, SNS), polyvinylpyrrolidone (polyvinylpyrrolidone, PVP), nonionic surfactant, polyethyleneimine (polyethyleneimine, PEI), and combinations thereof.

[0082] The above-described ceramic slurry composition for photocurable 3D printing may further include one or more additives selected from the group consisting of light-absorbing dyes, light-absorbing agents, silane coupling agents, and combinations thereof.

[0083] The light-absorbing dye may comprise 0.001 to 1 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing. Specifically, the light-absorbing dye may comprise 0.001 to 0.2 weight%, 0.1 to 0.3 weight%, 0.2 to 0.4 weight%, 0.3 to 0.5 weight%, 0.4 to 0.6 weight%, 0.5 to 0.7 weight%, 0.6 to 0.8 weight%, 0.7 to 0.9 weight%, or 0.8 to 1 weight% relative to the total weight of the ceramic slurry composition for photocurable 3D printing.

[0084] When a slurry prepared from the above-described ceramic slurry composition for photocurable 3D printing is applied to a photocurable 3D printer, light irradiated from the photocurable 3D printer collides with ceramic or glass ceramic powder particles within the slurry, causing light scattering. This phenomenon can cause a curing reaction even in areas not irradiated with light, which can be problematic for producing precise 3D molded bodies. Therefore, the above-described light-absorbing dye can be added as a composition to absorb the light irradiated from the photocurable 3D printer without scattering it.

[0085] The light-absorbing dye may include one or more selected from the group consisting of anthraquinone, diazo, isoindolinone, mono azo salts, benzimidazolone, diketopyrrolopyrrole, BONA lake, quinacridone, and combinations thereof.

[0086] The light absorber is configured to effectively absorb ultraviolet rays having a wavelength of 290 to 410 nm and block ultraviolet rays, thereby suppressing color tone changes caused by deterioration of the acrylate-based monomer, and may be included in an amount of 2 weight% or less relative to the total weight of the photocurable 3D printing ceramic slurry composition. Specifically, the light absorber may be included in an amount of 0.1 to 0.5 weight%, 0.5 to 1 weight%, 1 to 1.5 weight%, or 1.5 to 2 weight% relative to the total weight of the photocurable 3D printing ceramic slurry composition.

[0087] The above light absorber is 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine(2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine), 2-[4-[(2-hydroxy-3-(2-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine(2-[4-[(2-hydroxy-3-(2-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine), It may include one or more selected from the group consisting of Bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, Methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, and combinations thereof.

[0088] The above silane coupling agent is a component for coating (surface treating) the ceramic or glass ceramic powder particles and may comprise 24% by weight or less relative to the total weight of the ceramic slurry composition for photocurable 3D printing. Specifically, the silane coupling agent may comprise 0.1 to 2% by weight, 2 to 4% by weight, 4 to 6% by weight, 6 to 8% by weight, 8 to 10% by weight, or 10 to 12% by weight relative to the total weight of the ceramic slurry composition for photocurable 3D printing.

[0089] The ceramic or glass ceramic powder particles coated (surface treated) with the above silane coupling agent have excellent miscibility with liquids and can form a homogeneous solution (slurry), and since they have high chemical bonding ability with acrylate monomers (polymerizable monomers), they can have the effect of improving the strength of three-dimensional objects obtained through photocurable 3D printing.

[0090] The above silane coupling agents are 3-Glycidoxypropyl triethoxysilane, 8-Glycidoxyoctyltrimethoxysilane, p-styryltrimethoxysilane, 3-Methacryloxypropyl methyldimethoxysilane, 3-Methacryloxypropyl trimethoxysilane, 3-Methacryloxypropyl methyldiethoxysilane, and 3-Methacryloxypropyl triethoxysilane. 8-Methacryloxyoctyltrimethoxysilane, 3-Aryloxypropyl trimethoxysilane, N-2-(Aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(Aminoethyl)-3-aminopropyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Aminopropyltrimethoxysilane, 3-Triethoxysilyl-N-(1,3 dimethyl-butylidene) propylamine, N-Phenyl-3-aminopropyltrimethoxysilane,N-(Vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride), N-2-(aminoethyl)-8-aminooctyltrimethoxysilane, Methyltrimethoxysilane, Dimethyldimethoxysilane, Phenyltrimethoxysilane, Dimethoxydiphenylsilane, n-propyltrimethoxysilane, Hexyltrimethoxysilane, Decyltrimethoxysilane, It may include one or more selected from the group consisting of 1,6-Bis(trimethoxysilyl)hexane, 3,3,3-Trifluoropropyl trimethoxysilane, Tetraethoxysilane, Methyltriethoxysilane, Dimethyldiethoxysilane, Phenyltriethoxysilane, n-Propyltriethoxysilane, Hexyltriethoxysilane, Octyltriethoxysilane, Hexamethyldisilazane, Siloxane with hydrolyzable groups, and combinations thereof.

[0091] The present invention will be explained in more detail below through embodiments and the like, but the scope of the present invention is not limited by the embodiments presented below.

[0093] [Example]

[0094] Preparation Example 1: Preparation of ceramic powder

[0095] Yttria-stabilized zirconia (hereinafter referred to as 'zirconia') or lithium disilicate coated with a silane coupling agent (hereinafter referred to as 'lithium disilicate') was used as the ceramic powder. Here, yttria-stabilized zirconia is a ceramic material produced by adding yttria (Y2O3, yttrium oxide) to zirconia to maintain a stable cubic crystal structure even at room temperature.

[0096] The lithium disilicate ceramic powder coated with the above silane coupling agent was prepared using ethanol, distilled water, ceramic powder, and a silane coupling agent. First, 200g of ethanol, 15g of distilled water, and 100g of ceramic powder were stirred for 60 minutes.

[0097] 3g of a silane coupling agent (8-Methacryloxyoctyltrimethoxysilane) was added to the above stirred solution and stirred for 24 hours, then transferred to a drying oven and dried at 60°C for 24 hours to prepare lithium disilicate ceramic powder coated with a silane coupling agent.

[0098] Preparation Example 2: Preparation of a ceramic slurry for photocurable 3D printing

[0099] The zirconia or lithium disilicate ceramic powder of Preparation Example 1 above, butanediol diacrylate as an acrylate-based monomer, alkylol ammonium salt of a copolymer with acidic groups as a dispersant, bis-(2,4,6-trimethylbenzoyl)-phenylphosphine oxide as a photoinitiator, and polyethylene glycol, diethyl hexyl cyclohexane, polypropylene glycol, butyl glycidyl ether, ethylene glycol digylcidyl ether, and 2-ethyl hexyl phthalate as non-reactive diluents. Di-isononyl phthalate, Di-butyl phthalate, Tri-2-ethyl hexyl trimellitate, Di-2-ethyl hexyl adipate, Lauryl glycidyl ether, 1,4-butanediol diglycidyl ether, 2-butoxyethanol, Dioctyl terephthalate, and Disperse Orange 03 as a light-absorbing dye were each added in the content ratios listed in Table 1 below, and then dispersed twice for 5 minutes each at a speed of 2,000 rpm to produce a photocurable 3D printing ceramic slurry (Examples 1, 2, and 3). Comparative Examples 1 and 2) were prepared.Here, Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 were prepared by adding non-reactive diluent at different amounts of 3, 9, 13, 0, and 17 wt%. The detailed manufacturing processes for Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 are shown below.

[0100]

[0101] Example 1

[0102] As shown in Table 1 above, 70 wt% of ceramic powder, 20 wt% of acrylate-based monomer, 4.95 wt% of dispersant, 0.05 wt% of photoinitiator, 3 wt% of non-reactive diluent, and 0.005 wt% of light-absorbing dye were applied to Preparation Example 2 to prepare the photocurable 3D printing ceramic slurry of Example 1.

[0104] Example 2

[0105] A ceramic slurry for photocurable 3D printing was prepared with the same content as in Example 1, except that 16 wt% of an acrylate-based monomer and 9 wt% of a non-reactive diluent were used.

[0107] Example 3

[0108] A ceramic slurry for photocurable 3D printing was prepared with the same content as in Example 1, except that 12 wt% of an acrylate-based monomer and 13 wt% of a non-reactive diluent were used.

[0110] Comparative Example 1

[0111] A ceramic slurry for photocurable 3D printing was prepared with the same content as in Example 1, except that it contains 25% by weight of an acrylate-based monomer and does not contain a non-reactive diluent.

[0113] Comparative Example 2

[0114] A ceramic slurry for photocurable 3D printing was prepared with the same content as in Example 1, except that 8 wt% of an acrylate-based monomer and 17 wt% of a non-reactive diluent were used.

[0116] Preparation Example 3: Preparation of 3D printed output and sintered body

[0117] The ceramic slurry for photocurable 3D printing prepared in Manufacturing Example 2 above was printed using a DLP 3D printing device to form a ceramic 3D printed product, and then degreasing and sintering were performed to produce a sintered body.

[0118] The degreasing process is a critical step in the manufacturing of 3D printed objects and sintered bodies. The degreasing process poses a significant risk of part damage due to gases generated from the decomposition of the organic matrix and the resulting pressure. In particular, there is a high risk that small defects between individual layers will lead to cracking or the complete destruction of the part during degreasing. While this problem can be mitigated by increasing the binder removal time, it significantly extends the overall degreasing process time. Accordingly, the present invention performed a degreasing process according to heat treatment conditions that can reduce the risk of damage to parts occurring during degreasing and shorten the process time.

[0119] The sintering process is carried out through high-temperature firing in a sintering furnace, which leads to the compression and strengthening of fine ceramic powder, enabling the production of porous powder in a smaller form with increased strength.

[0120] (1) Debinding process

[0121] Table 2 below shows the heat treatment conditions for the degreasing process of a ceramic 3D printed product formed from a photocurable 3D printing ceramic slurry prepared using zirconia and lithium disilicate ceramic powders in Preparation Example 2 above.

[0122] The ceramic 3D printed object was placed in an electric furnace and heated from room temperature to 120°C at a heating rate of 1°C / min, and maintained for 120 minutes. Subsequently, it was heated to 210°C at a heating rate of 0.5°C / min and maintained for 180 minutes. Then, it was heated to 450°C at a heating rate of 0.5°C / min and maintained for 180 minutes. After the degreasing process was completed, it was subjected to natural cooling.

[0123]

[0124] (2) Sintering and Crystallization Process

[0125] Tables 3 and 4 below show the heat treatment conditions for the sintering process of ceramic 3D printed products formed from ceramic slurries for photocurable 3D printing, prepared using zirconia and lithium disilicate ceramic powders that have undergone the degreasing process described above.

[0126] When using zirconia ceramic powder, the debinded zirconia body was placed into a high-temperature electric furnace capable of heat treatment up to a temperature of 1700°C or higher, and then sintered according to the zirconia sintering process heat treatment conditions in Table 3 below.

[0127] After heating from room temperature to 1100℃ at a heating rate of 10℃ / minute and maintaining for 60 minutes, the temperature was then heated to an appropriate sintering temperature of 1450 to 1550℃ at a heating rate of 10℃ / minute and maintained for 120 minutes. Subsequently, it was naturally cooled to 200℃ inside the sintering furnace.

[0128] When using lithium disilicate ceramic powder, the above-mentioned debinded lithium disilicate body was introduced into an electric furnace capable of vacuum atmosphere control, which was preheated to 400°C, the sintering start temperature, and then sintered according to the lithium disilicate sintering process heat treatment conditions in Table 4 below.

[0129] The temperature was heated from 400℃ to 600℃ at a heating rate of 90℃ / min and held for 30 minutes, followed by heating to 890℃ at a heating rate of 10℃ / min and holding for 1 minute. During the heating and holding process, the section from 550℃ to 900℃ was conducted in a vacuum atmosphere of 200 bar. After the degreasing process was completed, the temperature was slowly cooled to 700℃ at a rate of 10℃ / min.

[0130]

[0131]

[0133] Experimental Example 1: Viscosity (Flowability) and Output Evaluation

[0134] Figure 1 is a graph showing the viscosity of different types of non-reactive diluents in Example 1, in which lithium disilicate was used as the ceramic powder.

[0135] Figure 2 is a graph showing the viscosity of different types of non-reactive diluents in Example 2, in which lithium disilicate was used as the ceramic powder.

[0136] Figure 3 is a graph showing the viscosity of different types of non-reactive diluents in Example 3, in which lithium disilicate was used as the ceramic powder.

[0137] Figure 4 is a graph showing the viscosity of different types of non-reactive diluents in Comparative Example 2, which used lithium disilicate as the ceramic powder.

[0138] Figure 5 is a graph showing the viscosity of different types of non-reactive diluents in Example 1, in which zirconia was used as the ceramic powder.

[0139] Figure 6 is a graph showing the viscosity of different types of non-reactive diluents in Example 2, in which zirconia was used as the ceramic powder.

[0140] Figure 7 is a graph showing the viscosity of different types of non-reactive diluents in Example 3, in which zirconia was used as the ceramic powder.

[0141] Figure 8 is a graph showing the viscosity of different types of non-reactive diluents in Comparative Example 2, which used zirconia as the ceramic powder.

[0142] Referring to FIGS. 1 to 8, regardless of the type of ceramic powder, as the content of the non-reactive diluent increased, that is, from Example 1 (non-reactive diluent content 3 wt%) to Comparative Example 2 (non-reactive diluent content 17 wt%), the viscosity of the composite resin composition for ceramic 3D printing tended to decrease. However, in the case of polyethylene glycol and polypropylene glycol, it was confirmed that the viscosity increased as the content increased, and the measured viscosity of the polyethylene glycol and polypropylene glycol was too high, so it was determined that they were not suitable as a composition for 3D printing.

[0143] Figure 9 is a photograph and graph showing the viscosity and disc specimen output results of Examples 1, 2, and 3, Comparative Example 1 and Comparative Example 2, using lithium disilicate as the ceramic powder and polyethylene glycol as the non-reactive diluent.

[0144] Figure 10 is a photograph and graph showing the viscosity and disc specimen output results of Examples 1, 2, and 3, Comparative Example 1 and Comparative Example 2, using lithium disilicate as the ceramic powder and polypropylene glycol as the non-reactive diluent.

[0145] Figure 11 is a photograph and graph showing the viscosity and disc specimen output results of Examples 1, 2, and 3, Comparative Example 1 and Comparative Example 2, using lithium disilicate as the ceramic powder and diethylhexyl cyclohexane as the non-reactive diluent.

[0146] Figure 12 is a photograph and graph showing the viscosity and disc specimen output results of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using lithium disilicate as the ceramic powder and dioctyl terephthalate as the non-reactive diluent.

[0147] Figure 13 is a photograph and graph showing the viscosity and disc specimen output results of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using lithium disilicate as the ceramic powder and 1,4-butanediol glycidyl ether as the non-reactive diluent.

[0148] Figure 14 is a photograph and graph showing the viscosity and disc specimen output results of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using lithium disilicate as the ceramic powder and 2-butoxyethanol as the non-reactive diluent.

[0149] The compositions shown in FIGS. 9 to 14 were prepared under curing conditions of a stacking thickness of 50 μm and a curing time of 3 seconds when outputting disk specimens.

[0150] As a result, in the case of diethylhexyl cyclohexane, dioctyl terephthalate, and 1,4-butanediol glycidyl ether shown in FIGS. 11 to 13, it was confirmed that the viscosity decreased as the content of the non-reactive diluent increased, and it was confirmed that the compositions of Examples 1 to 3 and Comparative Example 1 were capable of output.

[0151] However, in the case of 2-butoxyethanol shown in Fig. 14, it was confirmed that the viscosity decreased as the content of the non-reactive diluent increased, but despite the good viscosity of the compositions of Example 2, Example 3 and Comparative Example 2, interference occurred in radical polymerization, preventing them from bonding tightly and causing them to detach from the stage during printing, making printing impossible.

[0152] In the case of polyethylene glycol and polypropylene glycol shown in Figures 9 and 10, it was confirmed that the viscosity increased as the content of the non-reactive diluent increased, and due to the stickiness caused by the high viscosity, bubbles were trapped and could not be laminated uniformly, and the specimen was pushed during blade movement, making printing impossible.

[0153] In other words, it was confirmed that using an excessive amount of non-reactive diluent or a non-reactive diluent with poor suitability affects photocuring, making deposition impossible due to a low curing thickness, and it was found that the content and material of the non-reactive diluent have a significant impact on the curing thickness, which is an important factor in the additive manufacturing 3D printing process.

[0154] Accordingly, it was found that the optimal content ratio of the non-reactive diluent added to the ceramic slurry composition for photocurable 3D printing is 3 to 13 weight percent, and it was found that 2-butoxyethanol, polyethylene glycol, and polypropylene glycol are not suitable for use as non-reactive diluents.

[0155] Figure 15 is a graph showing the viscosity of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using zirconia as the ceramic powder and polypropylene glycol as the non-reactive diluent.

[0156] Figure 16 is a graph showing the viscosity of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using zirconia as the ceramic powder and diethylhexyl cyclohexane as the non-reactive diluent.

[0157] Figure 17 is a graph showing the viscosity of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using zirconia as the ceramic powder and dioctyl terephthalate as the non-reactive diluent.

[0158] Figure 18 is a graph showing the viscosity of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, using zirconia as the ceramic powder and 1,4-butanediol glycidyl ether as the non-reactive diluent.

[0159] Figure 19 is a graph showing the viscosity of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2, in which zirconia was used as the ceramic powder and 2-butoxyethanol was used as the non-reactive diluent.

[0160] In the case of diethylhexyl cyclohexane, dioctyl terephthalate, 1,4-butanediol glycidyl ether, and 2-butoxyethanol shown in FIGS. 16 to 19, it was confirmed that the viscosity decreased as the content of the non-reactive diluent increased.

[0161] In the case of the polypropylene glycol shown in Fig. 15, it was confirmed that the viscosity increased as the content of the non-reactive diluent increased.

[0163] Experimental Example 2: Evaluation of Photocuring Depth

[0164] Figure 20 is a graph showing the photocuring depth of Example 2 according to the type of non-reactive diluent, using lithium disilicate as the ceramic powder. At this time, to verify the photocuring depth, the photocuring depth was measured by irradiating with light for 3 seconds.

[0165] As a result, the slurry containing dioctyl terephthalate, 1,4-butanediol diglycidyl ether, and diethylhexyl cyclohexane exhibited a curing thickness of approximately 80 μm, whereas the slurry containing 2-butoxyethanol formed a curing thickness of less than 50 μm. This confirmed that the 2-butoxyethanol non-reactive diluent exhibited a lower curing thickness compared to the dioctyl terephthalate, diglycidyl ether, and diethylhexyl cyclohexane non-reactive diluents, which were subjected to light irradiation for the same amount of time under conditions that weaken interlayer bonding during photocuring.

[0167] Experimental Example 3: Evaluation of Biaxial Strength of Photocurable Ceramic 3D Printed Structures

[0168] Figure 21 is a graph and scanning electron microscope (SEM) image showing the results of measuring the biaxial strength of a photocurable ceramic 3D printed structure prepared using Example 1, which used lithium disilicate as the ceramic powder and dioctyl terephthalate, 1,4-butanediol diglycidyl ether, diethylhexyl cyclohexane, polypropylene glycol, or 2-butoxyethanol as non-reactive diluents.

[0169] As shown in Fig. 21, in the case of a ceramic 3D printed structure containing polypropylene glycol in which bubbles were trapped during the deposition process due to high viscosity, the strength was found to be 103 MPa, and SEM analysis confirmed that the trapped bubbles remained as closed pores even after sintering. In other words, it was found that the pores in the sintered body are a major factor in reducing strength and permeability, and thus cause a degradation of physical properties.

[0170] In addition, it was confirmed that in the case of ceramic 3D printed structures containing 2-butoxyethanol, interlayer delamination occurred due to improper layering caused by the low curing thickness, resulting in reduced strength. Many pores were also observed in the SEM results.

[0171] The ceramic structure containing 1,4-butanediol diglycidyl ether showed the highest value of 355 MPa in biaxial strength. SEM measurements confirmed that a lithium disilicate crystalline phase also grew properly within the glassy phase.

[0172] FIG. 22 is a graph showing the results of measuring the flexural strength of a photocurable ceramic 3D printed structure prepared using Example 1, which used zirconia as the ceramic powder and dioctyl terephthalate, 1,4-butanediol diglycidyl ether, diethylhexyl cyclohexane, polypropylene glycol, or 2-butoxyethanol as non-reactive diluents, and a photograph of the sintered body.

[0173] As shown in Fig. 22, it was confirmed that in the case of ceramic 3D printed structures containing zirconia, when polypropylene glycol and 2-butoxyethanol are used as non-reactive diluents, cracks occur after sintering and exhibit low flexural strength values.

[0174] It was confirmed that when 1,4-butoxyethanol diglycidyl ether is used as a non-reactive diluent, it is sintered without cracking and exhibits a maximum flexural strength value of 366 MPa.

[0175] FIG. 23 is a graph and scanning electron microscope (SEM) image showing the results of measuring the biaxial strength of photocurable ceramic 3D printed structures prepared using Examples 1 to 3 and Comparative Example 1, in which lithium disilicate was used as the ceramic powder and 1,4-butanediol diglycidyl ether was used as the non-reactive diluent.

[0176] As shown in Fig. 23, the biaxial strength of the ceramic 3D printed structure according to the content of 1,4-butanediol diglycidyl ether was found to be up to 372 MPa.

[0177] Through this, it was confirmed that when a non-reactive diluent is added within a weight range, the non-reactive diluent acts as an inter-particle lubricant during the initial degreasing stage, increasing the mobility of gases generated by the decomposition of polymers during the degreasing process and facilitating crack prevention.

[0178] On the other hand, it was confirmed that in the case of ceramic 3D printed structures not containing 1,4-butanediol diglycidyl ether, the mobility of the gas generated during the degreasing process is limited, and non-uniformity occurs due to internal pressure caused by the gas, and residual pores and cracks propagate, resulting in a decrease in biaxial strength. In other words, when a non-reactive diluent is not included, the viscosity of the slurry becomes excessively high, limiting the solid content to 50 vol% or less; consequently, molding non-uniformity and residual pores increase, and it was found that these pores act as crack propagation paths, leading to a decrease in strength.

[0179] Therefore, it was confirmed that by including a non-reactive diluent within the optimal weight range, the viscosity of the slurry is reduced, thereby suppressing aggregation between particles and making the dispersion uniform, which reduces defects in the initial stage of degreasing and consequently densifying the particles during the sintering process, thereby increasing biaxial strength.

[0180] FIG. 24 is a graph and scanning electron microscope (SEM) image showing the results of measuring the biaxial strength of photocurable ceramic 3D printed structures prepared with a composition containing 9 wt% by weight of 1,4-butanediol diglycidyl ether as a non-reactive diluent and different amounts of lithium disilicate ceramic powder (solid content) (see content shown in Table 5 below).

[0181]

[0182] The addition of 9 wt% of a non-reactive diluent lowers the viscosity of the composition, thereby suppressing aggregation between particles and ensuring uniform dispersion, which reduces defects during the initial degreasing stage and consequently enables particle densification during sintering, which can increase biaxial strength. In other words, it can be confirmed that even when a large amount of ceramic powder (solid content) is included due to the non-reactive diluent, the biaxial strength improves in proportion to the ceramic powder (solid content) content.

[0183] As a result of SEM measurement, many pores were observed in ceramic 3D printed structures containing 50 vol% or less of solids, and in ceramic 3D printed structures containing 50 vol% or more of solids, the permeability of the sintered body was improved due to increased strength and reduced pores.

[0184] On the other hand, referring to FIGS. 9 and 10, when polyethylene glycol and polypropylene glycol were included in 9 wt%, it was impossible to print the output. Therefore, it was not possible to measure the biaxial strength of photocurable ceramic 3D printed structures made with compositions containing lithium disilicate ceramic powders of different contents.

[0185] In other words, it was found that depending on the type of non-reactive diluent added to the ceramic slurry composition for photocurable 3D printing, it is possible to produce a slurry with low viscosity while containing a high amount of ceramic powder, and that a ceramic 3D printed structure using this can produce a high-quality 3D molded article by containing more than 50 vol% of solids.

Claims

Claim 1 Ceramic or glass ceramic powder; acrylate-based monomer; photoinitiator; non-reactive diluent; and, a dispersant; wherein the non-reactive diluent comprises Diethyl hexyl cyclohexane, Butyl glycidyl ether, Ethylene glycol digylcidyl ether, 2-ethyl hexyl phthalate, Di-isononyl phthalate, Di-butyl phthalate, Tri-2-ethyl hexyl trimellitate, Di-2-ethyl hexyl adipate, Lauryl glycidyl ether, 1,4-Butanediol diglycidyl ether, and Dioctyl A ceramic slurry composition for photocurable 3D printing, characterized by comprising one or more selected from the group consisting of terephthalate (dioctyl terephthalate) and combinations thereof, and comprising the non-reactive diluent to comprise 40 to 85 weight% of the ceramic or glass ceramic powder, thereby enabling the production of a photocurable ceramic 3D printed structure having a biaxial strength (or flexural strength) of 200 to 600 MPa or more. Claim 2 A ceramic slurry composition for photocurable 3D printing according to claim 1, characterized in that the ceramic slurry composition comprises: 40 to 85 weight% of the ceramic or glass ceramic powder; 5 to 30 weight% of the acrylate-based monomer; 0.04 to 1 weight% of the photoinitiator; 3 to 13 weight% of the non-reactive diluent; and 1 to 9 weight% of the dispersant. Claim 3 delete Claim 4 In claim 1, the ceramic or glass ceramic powder comprises zirconia (ZrO2), alumina (Al2O3), zirconia-alumina composite (ZrO2-Al2O3), yttria (Y2O3), titania (TiO2), silica (SiO2), magnesia (MgO), silicon nitride (Si3N4), titanium nitride (TiN), aluminum nitride (AlN), silicon carbide (SiC), boron carbide (B4C), spinel (MgAl2O4), mullite (3Al2O3·2SiO2), tantalum carbide (TaC), boron nitride (BN), zinc oxide (ZnO), zinc sulfate (ZnSO4), barium sulfate (BaSO4), magnesium fluoride (MgF2), and thorium fluoride (ThF4). A photocurable 3D printing ceramic slurry composition characterized by comprising one or more selected from the group consisting of yttrium fluoride (YF3), crystallized glass, tricalcium phosphate (TCP), octacalcium phosphate (OCP), fluoridated hydroxyapatite (FHA), biphasic calcium phosphate (BCP), calcium sulfate (CaSO4), calcium silicate, bioglass, feldspar, lithium disilicate, lucitite, hydroxyapatite (HA), and combinations thereof. Claim 5 A ceramic slurry composition for photocurable 3D printing according to claim 1, characterized in that the acrylate-based monomer comprises one or more selected from the group consisting of monofunctional monomers, difunctional monomers, polyfunctional monomers, oligomer monomers, and combinations thereof. Claim 6 delete Claim 7 A ceramic slurry composition for photocurable 3D printing according to claim 1, characterized in that the ceramic slurry composition for photocurable 3D printing further comprises one or more additives selected from the group consisting of light-absorbing dyes, light-absorbing agents, silane coupling agents, and combinations thereof. Claim 8 A ceramic slurry composition for photocurable 3D printing according to claim 7, wherein the light-absorbing dye comprises one or more selected from the group consisting of anthraquinone, diazo, isoindolinone, mono azo salts, benzimidazolone, diketopyrrolopyrrole, BONA lake, quinacridone, and combinations thereof. Claim 9 In claim 7, the light absorber is 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine(2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine), 2-[4-[(2-hydroxy-3-(2-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine(2-[4-[(2-hydroxy-3-(2-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine), A photocurable ceramic slurry composition for 3D printing characterized by comprising one or more selected from the group consisting of Bis(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, Methyl(1,2,2,6,6-pentamethyl-4-piperidinyl)sebacate, and combinations thereof. Claim 10 A ceramic slurry composition for photocurable 3D printing according to claim 1, characterized in that the slurry prepared from the ceramic slurry composition for photocurable 3D printing has a viscosity in the range of 350 to 40,000 cP.

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