Method for manufacturing high-transmittance lithium disilicate glass ceramic by means of photocuring additive manufacturing

Abstract

The present invention relates to a method for manufacturing a high-transmittance lithium disilicate glass ceramic by means of photocuring additive manufacturing, comprising: adding anhydrous ethanol to prepared powder, carrying out ball milling for uniform mixing and then drying the mixture, and carrying out heat treatment to obtain a molten mixture; dropwise adding the molten mixture to flowing deionized water for quenching to form initial particles; ball-milling and sieving the initial particles to prepare powder having a particle size of 0.3-0.5 μm and carrying out spray drying granulation to obtain 5-25 μm glass ceramic particles; adding the glass ceramic particles to a prepared resin mixture, putting the obtained mixture into a roller press to prepare a paste, and then carrying out vacuum defoaming; carrying out photocuring formation on the paste by means of an additive manufacturing device to obtain a green body; using a flowing cleaning solution to clean the green body and then drying the green body; and degreasing the dried green body in vacuum or an inert gas, then carrying out vacuum impregnation in a lithium polysilicate solution, and then carrying out sintering and ion exchange to obtain a finished product. The present invention solves the problem of insufficient strength or low light transmittance of a lithium disilicate glass ceramic obtained by additive manufacturing.

Description

Method for light-curing additive manufacturing of highly transparent lithium disilicate glass-ceramics Technical Field

[0001] The present invention relates to the technical field of lithium disilicate glass ceramic preparation, and in particular to a method for manufacturing highly transparent lithium disilicate glass ceramic by photocuring additive manufacturing. Background Art

[0002] Lithium disilicate glass-ceramics have been used clinically as dental restorative materials for many years. The preparation of lithium disilicate glass-ceramic crowns using 3D printing technology is currently a technological approach that effectively reduces raw material waste. 3D printing technologies primarily include stereolithography (SLA), selective laser sintering (SLS), direct ink writing (DIW), and extrusion forming (EFF).

[0003] However, existing methods of preparing lithium disilicate glass-ceramics based on 3D printing technology have the problem of low strength. In some solutions, the flexural strength of the obtained lithium disilicate glass-ceramics is less than 100 MPa, which does not meet the standard dental standard of a single crown flexural strength of more than 300 MPa, and therefore cannot be used as a single crown restoration. In other solutions, the strength of lithium disilicate glass-ceramics obtained by additive manufacturing is between 150 and 250 MPa, and then after a complex chemical strengthening (ion exchange) process, the strength can exceed 300 MPa, but they are all immersed in a static molten salt. This method is time-consuming, inefficient, and difficult to control the depth of ion exchange. There are also some solutions, such as the high-strength and high-permeability lithium disilicate glass-ceramics and their preparation methods and applications disclosed in patent CN202110901288.X. The excessive number of heat treatments will affect the performance of the lithium disilicate glass-ceramics. In addition, the molding of the block by hot pressing will greatly increase the post-processing cost, while the molding by the lost wax method has lower precision.

[0004] Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention provides a method for photocuring additive manufacturing of highly transparent lithium disilicate glass ceramics, which solves the problem that the lithium disilicate glass ceramics obtained by the existing additive manufacturing method have low flexural strength or high strength but poor light transmittance.

[0006] The technical solution adopted in the present invention is as follows:

[0007] A method for photocuring additive manufacturing of highly transparent lithium disilicate glass ceramics, comprising:

[0008] S1. Prepare a powder according to the following components in percentage by mass: 59% to 70% SiO2, 14% to 20% Li2O, 3% to 5% K2O, 1% to 5% P2O5, 1% to 3% ZnO and other components, wherein the other components include Al2O3, ZrO2, Na2O, Tb4O7, La2O3, CeO2, MgO, Y2O3, and CaO;

[0009] S2, adding anhydrous ethanol to the powder, mixing uniformly by ball milling, drying, and then heat treating to obtain a molten mixture;

[0010] S3, dropping the molten mixture into deionized water in a stable flow state to quench it, forming initial particles in the deionized water, wherein D50 of the initial particles is ≤1 mm;

[0011] S4, ball-milling and sieving the initial particles to prepare a powder with a particle size of D50 = 0.3-0.5 μm, and then granulating the powder by spray drying to obtain lithium disilicate glass ceramic particles with a size of 5-25 μm;

[0012] S5, mixing the photosensitive resin premix, dispersant, and photoinitiator to obtain a resin mixture;

[0013] S6, adding the lithium disilicate glass ceramic particles obtained in step S4 to the resin mixture in multiple portions, placing the mixture in a roller press and rolling it at least once to obtain a rolled mixture, adding nano-fumed silica to the rolled mixture to obtain a paste, and placing the paste in a vacuum machine for vacuum degassing;

[0014] S7, placing the paste into an additive manufacturing device for light-curing forming to obtain a green body;

[0015] S8, cleaning the green body with a flowing cleaning solution, and then drying;

[0016] S9, degreasing and sintering:

[0017] Degreasing the green body in vacuum or inert gas: the temperature is first raised from room temperature to 200°C at a heating rate of 1°C / min, then successively raised from 200°C to 400°C at a heating rate of 0.5°C / min, and from 400°C to 500°C at a heating rate of 1°C / min, and kept at 500°C for 2 hours; then, air is introduced, the temperature is raised from 500°C to 600°C at a heating rate of 2°C / min, kept at this temperature for 1 hour, and then lowered to room temperature at a cooling rate of 2°C / min to obtain a degreased sample;

[0018] The degreased sample is placed in a 21% to 24% lithium polysilicate solution for vacuum impregnation. After the predetermined impregnation time is completed, sintering is performed: heating to 500°C in air, then evacuating with the vacuum degree controlled below 10 mbar, and then heating to 630°C, holding the temperature for 2 hours, then heating to 800 to 950°C at a heating rate of 2°C / min, holding the temperature for 1 hour, and then cooling to room temperature at a rate of 2°C / min to obtain a sintered sample;

[0019] S10, ion exchange: placing the sintered sample in a high-pressure vacuum furnace in a flowing nitrate under the action of a stirring device, heating to 300-600°C under vacuum conditions, immersing the sintered sample in the molten nitrate to undergo an ion exchange reaction therewith, the reaction time being 0.5-2 hours, and finally obtaining the product; the nitrate is a mixture of sodium nitrate and rubidium nitrate in a mass ratio of 1:1.

[0020] Further technical solutions are:

[0021] In step S3, the temperature of the deionized water is 20-25° C., and the flow rate is 0.5-2 m / s.

[0022] In step S4, the particle size of the lithium disilicate glass ceramic particles of 5 to 25 μm presents a bimodal distribution, with two peaks at 5 μm and 25 μm, respectively.

[0023] In step S6, the mass of the lithium disilicate glass ceramic particles accounts for 70% to 85% of the paste, the mass of the nano-fumed silica accounts for 0.1% to 0.5% of the paste, and the particle size of the nano-fumed silica is 7 nanometers.

[0024] The photosensitive resin premix comprises a monofunctional photosensitive resin monomer, a bifunctional photosensitive resin monomer and a multifunctional photosensitive resin monomer in a mass ratio of 1:1:1 to 1:2:3;

[0025] The monofunctional photosensitive resin monomer includes one or more of hydroxyethyl methacrylate, lauryl acrylate, isobornyl acrylate, phenoxyethyl acrylate, and lauric acid methacrylate;

[0026] The bifunctional photosensitive resin monomer includes one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, and dipropylene glycol diacrylate;

[0027] The trifunctional photosensitive resin monomer includes propoxylated glycerol triacrylate or ethoxylated trimethylolpropane triacrylate.

[0028] The mass of the photoinitiator accounts for 0.5% to 2% of the mass of the photosensitive resin premix;

[0029] The photoinitiator includes one or both of diphenyl 2,4,6-trimethylbenzoylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone;

[0030] The mass ratio of diphenyl 2,4,6-trimethylbenzoylphosphine oxide to 1-hydroxycyclohexyl phenyl ketone is 1:1.

[0031] The dispersant includes gamma-methacryloxypropyltrimethoxysilane and gamma-glycidoxypropyltrimethoxysilane in a mass ratio of 1:1.

[0032] In step S7, the cleaning solution includes hexanediol diacrylate, isopropyl alcohol and polyethylene glycol 200 in a mass ratio of 1:1:1.

[0033] In step S2, the temperature of the heat treatment is 1400-1600°C.

[0034] A lithium disilicate glass ceramic prepared according to the method for manufacturing high-transmittance lithium disilicate glass ceramics by light-curing additive manufacturing, wherein the lithium disilicate glass ceramic has a flexural strength of 480-530 MPa, a hardness of 6-8 GPa, and a light transmittance of 40%-50%.

[0035] The beneficial effects of the present invention are as follows:

[0036] The method of the present invention improves the flexural strength of lithium disilicate glass-ceramics without sacrificing light transmittance, thereby meeting the mechanical property and light transmittance requirements of a standard dental single crown. Specifically, it has the following advantages:

[0037] (1) The present invention improves the degreasing and sintering processes by quenching with flowing deionized water. On the one hand, the heat of the molten mixture is quickly taken away by the flowing water in a short time, which prevents the accumulation of particles formed by quenching, reduces the generation of large particles, and obtains small-sized particles, thereby effectively reducing the particle size after quenching and improving the particle uniformity. It not only shortens the subsequent ball milling time, but also facilitates the formation of more rod-shaped crystals during subsequent sintering. On the other hand, different temperature rise stages are set to regulate the corresponding degreasing and sintering atmospheres and parameters, thereby avoiding cracks and carbon residues, and further promoting the generation of rod-shaped crystals. The interlocking structure formed by the rod-shaped grains greatly improves the mechanical properties and light transmittance.

[0038] (2) The present invention adjusts the microstructure of the product, reduces pore formation, and improves density by controlling the parameters of degreasing and sintering, including atmosphere, sintering temperature, holding time, and impregnation conditions.

[0039] (3) The present invention utilizes fluidized nitrate to carry out ion exchange with the sintered sample under high-pressure vacuum conditions, thereby further improving the flexural strength of the product, while increasing the ion exchange rate and shortening the reaction time.

[0040] (4) The method of the present invention is simple to operate, does not require a large amount of heat treatment and post-processing processes, has low energy consumption, and high processing efficiency.

[0041] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] FIG1 is a schematic flow diagram of the method of the present invention.

[0043] FIG2 is a SEM image of the lithium disilicate glass ceramic particles obtained in step S4 of the method of Example 1 of the present invention.

[0044] FIG3 is a physical picture of the dental crown product prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0045] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0046] Example 1

[0047] As shown in FIG1 , a method for photocuring additive manufacturing of highly transparent lithium disilicate glass ceramics in Example 1 includes:

[0048] S1. Prepare powder according to the following mass percentage components: 59% to 70% SiO2, 14% to 20% Li2O, 3% to 5% K2O, 1% to 5% P2O5, 1% to 3% ZnO and other components, wherein the other components include Al2O3, ZrO2, Na2O, Tb4O7, La2O3, CeO2, MgO, Y2O3, and CaO.

[0049] S2, adding anhydrous ethanol to the powder, mixing uniformly by ball milling, drying, and then heat treating at a temperature of 1400-1600° C. to obtain a molten mixture;

[0050] Specifically, a planetary ball mill can be used for ball milling mixing, with a rotation speed of 400-600 r / min and a ball milling time of 20 hours;

[0051] S3, dropping the molten mixture into deionized water in a stable flow state to quench it, forming initial particles in the deionized water, wherein D50 of the initial particles is 1 mm;

[0052] The temperature of the deionized water is room temperature, specifically 20-25° C., and the flow rate is 0.5 m / s.

[0053] S4, the initial particles are sieved through a zirconium bead ball mill to prepare a powder with a particle size of D50 = 0.3-0.5 μm, and then granulated by spray drying to obtain lithium disilicate glass ceramic particles of 5-25 μm;

[0054] Among them, the particle size of lithium disilicate glass ceramic particles ranging from 5 to 25 μm presents a bimodal distribution, with two peaks at 5 μm and 25 μm respectively;

[0055] S5, mixing the photosensitive resin premix, dispersant, and photoinitiator to obtain a resin mixture;

[0056] The photosensitive resin premix comprises a monofunctional photosensitive resin monomer, a bifunctional photosensitive resin monomer and a multifunctional photosensitive resin monomer in a mass ratio of 1:1:1 to 1:2:3;

[0057] The monofunctional photosensitive resin monomer includes one or more of hydroxyethyl methacrylate, lauryl acrylate, isobornyl acrylate, phenoxyethyl acrylate, and lauric acid methacrylate;

[0058] The bifunctional photosensitive resin monomer includes one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, and dipropylene glycol diacrylate;

[0059] The trifunctional photosensitive resin monomer includes propoxylated glycerol triacrylate or ethoxylated trimethylolpropane triacrylate;

[0060] The mass of the photoinitiator accounts for 0.5% to 2% of the mass of the photosensitive resin premix;

[0061] The photoinitiator includes one or both of diphenyl 2,4,6-trimethylbenzoylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone; the mass ratio of diphenyl 2,4,6-trimethylbenzoylphosphine oxide to 1-hydroxycyclohexyl phenyl ketone is 1:1;

[0062] The dispersant includes gamma-methacryloxypropyltrimethoxysilane and gamma-glycidoxypropyltrimethoxysilane in a mass ratio of 1:1.

[0063] S6, adding the lithium disilicate glass ceramic particles obtained in step S4 to the resin mixture in multiple portions, then placing the mixture in a roller press and rolling it at least once to obtain a rolled mixture, adding nano-fumed silica to the rolled mixture to obtain a paste, and placing the paste in a vacuum machine for vacuum degassing;

[0064] The mass of the lithium disilicate glass ceramic particles accounts for 70% to 85% of the paste, the mass of the nano-fumed silica accounts for 0.1% to 0.5% of the paste, and the particle size of the nano-fumed silica is 7 nanometers.

[0065] S7, placing the paste into an additive manufacturing device for photocuring to obtain a green body;

[0066] It can be understood that according to the design plan, the printing parameters are adaptively set to obtain a crown blank that meets individual needs and is suitable for the target use;

[0067] S8, washing the green body with a flowing washing solution, and then drying it with cold air drying;

[0068] The cleaning solution includes hexanediol diacrylate, isopropyl alcohol and polyethylene glycol 200 in a mass ratio of 1:1:1.

[0069] S9, degreasing and sintering:

[0070] Degreasing the green body in vacuum or inert gas, first raising the temperature from room temperature to 200°C at a heating rate of 1°C / min, then successively raising the temperature from 200°C to 400°C at a heating rate of 0.5°C / min, and from 400°C to 500°C at a heating rate of 1°C / min, and keeping the temperature at 500°C for 2 hours; then slowly introducing room temperature air at a rate of 0.5 to 2 L / min, then raising the temperature from 500°C to 600°C at a heating rate of 2°C / min, keeping the temperature for 1 hour, and then cooling to room temperature at a cooling rate of 2°C / min to obtain a degreased sample;

[0071] The degreased sample was placed in a lithium polysilicate solution with a concentration of 21% to 24% and vacuum impregnated for a total of 5 times, each time for 1 hour. After the impregnation was completed, the sample was heated to 500° C. in air, and then vacuumed with the vacuum degree controlled below 10 mbar. The temperature was further increased to 630° C. and kept at this temperature for 2 hours. The temperature was then increased to 950° C. at a heating rate of 2° C. / min, kept at this temperature for 1 hour, and then cooled to room temperature at a rate of 2° C. / min to obtain a sintered sample.

[0072] Debinding and sintering can be carried out using tubular heating equipment.

[0073] S10. Ion exchange: placing the sintered sample in a high-pressure vacuum furnace in a flowing nitrate under the action of a stirring device, heating to 300-600°C under vacuum conditions, immersing the sintered sample in the molten nitrate to undergo an ion exchange reaction therewith, the reaction time being 0.5-2 hours, and finally obtaining a crown product; the nitrate is a mixture of sodium nitrate and rubidium nitrate in a mass ratio of 1:1.

[0074] Specifically, the sintered sample is placed in an alumina crucible, and then the whole is placed in nitrate in a high-pressure vacuum furnace for heating to facilitate obtaining the product after the reaction.

[0075] Among them, the purpose of ion exchange is to use large-sized cations (sodium and rubidium ions) to replace small-sized ions (lithium ions) to form a plugging effect. Residual compressive stress will be generated on the surface without changing the microstructure, thereby improving the mechanical properties.

[0076] In this embodiment, nitrate is used for ion exchange because it is relatively stable, easy to remove, and will not form insoluble precipitated compounds with the exchanged ions.

[0077] In this embodiment, ion exchange is performed under vacuum conditions, which draws out gas molecules, thereby increasing the space and rate of ion exchange. This helps accelerate ion diffusion and penetration, increasing the migration rate of ions within the material, thereby shortening the ion exchange time and improving exchange efficiency. Furthermore, the nitrate is in a mobile state, further increasing the exchange rate.

[0078] Compared with the time required for ion exchange in a static molten state of nitrate, which is more than 8 hours, the ion exchange under high pressure vacuum conditions in this embodiment can be completed in only 0.5-2 hours.

[0079] In step S3 of this embodiment, deionized water at a steady flow rate of 0.5 m / s at 20-25°C is used for quenching. Compared with quenching with static deionized water, this improves the heat dissipation effect and can make the particles smaller and more uniform after cooling. The reduced particle size is conducive to the subsequent sintering process, which forms an interlocking structure and helps improve mechanical properties. In addition, the reduced particle size shortens the time required for the subsequent step S4 to ball mill the powder to a particle size of 0.3-0.5 μm, thereby improving preparation efficiency.

[0080] In step S5 of this embodiment, the introduction of a dispersant can introduce groups, which is beneficial for uniform dispersion in the organic resin and increasing the solid content. Specifically, according to the condensation mechanism, the silane molecules directly condense with the surface hydroxyl groups in the silica through the -OCH3 groups in the silane, chemically bonding to the surface of the filler particles to form a covalent bond (oxyalkylene bond, Si-O-Si). The -OCH3 groups on adjacent silane molecules can also condense with each other.

[0081] In step S5 of this embodiment, the addition of nano-fumed silica modifies the rheological properties, similar to a Bingham fluid, without affecting its viscosity. Shear thinning occurs, and in the absence of external forces, the original state remains unchanged, without introducing new impurities and thus affecting light transmittance.

[0082] In step S8 of this embodiment, a flowing cleaning solution is used for cleaning, ensuring efficiency while preventing the interlayer bonding of the 3D-printed green body. The cleaning solution used reduces the concentration of isopropyl alcohol, preventing it from dissolving the solidified resin within a short period of time. Furthermore, the flowing cleaning solution quickly removes excess paste material, thereby improving cleaning efficiency.

[0083] Compared with the conventional degreasing method in air, step S9 of this embodiment degreases in vacuum or inert gas. The main purpose is to control the oxygen content below 500°C, effectively avoiding the simultaneous occurrence of thermal cracking reaction and oxidation reaction, thereby avoiding the generation of a large amount of gas in a short time and causing cracks. The temperature reaches above 500°C, and then slowly introduces air and then heats up again. The purpose is to remove the carbon remaining due to the thermal cracking reaction. The temperature is then lowered for impregnation. The purpose of impregnation with lithium polysilicate solution is that there are pores in the green body after the lithium disilicate glass ceramic is degreased. Through impregnation, lithium polysilicate can fill these pores, thereby improving the density of the green body. After that, the temperature is raised from room temperature to 500°C, and further oxidation reaction is carried out to remove carbon. Then, the temperature is continued to be raised under vacuum conditions below 10mbar. More rod-shaped grains can be generated, the transmittance is increased, and at the same time, pore formation is prevented under vacuum, the density is improved, and the strength is thereby improved.

[0084] Mechanical testing was performed on the light-cured additively manufactured high-transmittance lithium disilicate glass-ceramic crown prepared in Example 1, and the results showed that the crown had a flexural strength of 480 MPa, a hardness of 6 GPa, and a light transmittance of 42%.

[0085] As shown in FIG2 , the lithium disilicate glass ceramic particles prepared in this embodiment have a bimodal distribution. During the paste preparation process, the bimodal distribution of particles can effectively reduce the pores between particles compared with the accumulation of particles with a single particle size, thereby facilitating an increase in the solid content of the paste.

[0086] Example 2

[0087] In the second embodiment, a method for photocuring additive manufacturing of highly transparent lithium disilicate glass ceramics is provided. The preparation process and other parameters are the same as those in the first embodiment. The difference is:

[0088] In step S3, the flow rate of the stable flow deionized water is 1 m / s, and the D50 of the initial particles obtained by quenching is 0.9 mm;

[0089] In step S9, after the impregnation is completed, heat to 500°C in the air, then evacuate, control the vacuum degree below 10mbar, continue to heat to 630°C, keep warm for 2 hours, then continue to heat to 800°C, the heating rate is 2°C / min, keep warm for 1 hour, and then cool to room temperature at 2°C / min to obtain the crown product.

[0090] Mechanical tests and light transmittance tests were performed on the light-cured additively manufactured high-transmittance lithium disilicate glass-ceramic crown prepared in Example 2. The results showed that the crown had a flexural strength of 500 MPa, a hardness of 7 GPa, and a light transmittance of 46%.

[0091] Example 3

[0092] In the third embodiment, a method for manufacturing highly transparent lithium disilicate glass ceramics by photocuring additive manufacturing is provided. The preparation process and other parameters are the same as those in the first embodiment. The difference is:

[0093] In step S3, the flow rate of the stable flow deionized water is 2 m / s, and the D50 of the initial particles obtained by quenching is 0.8 mm;

[0094] In step S9, after the impregnation is completed, heat to 500°C in the air, then evacuate, control the vacuum degree below 10mbar, continue to heat to 630°C, keep warm for 2 hours, then continue to heat to 875°C, the heating rate is 2°C / min, keep warm for 1 hour, and then cool to room temperature at 2°C / min to obtain the crown product.

[0095] Mechanical tests and light transmittance tests were performed on the light-cured additively manufactured high-transmittance lithium disilicate glass-ceramic crown prepared in Example 3. The results showed that the crown had a flexural strength of 530 MPa, a hardness of 8 GPa, and a light transmittance of 50%.

[0096] As shown in FIG3 , which is a real picture of the dental crown product of Example 3, it can be seen that the product has good light transmittance.

[0097] Comparative Example 1

[0098] In this comparative example, a method for manufacturing highly transparent lithium disilicate glass ceramics by photocuring additive manufacturing is used. The preparation process and other parameters are the same as those in Example 3, except that:

[0099] In step S3, the flow rate of the stable flow deionized water is 0, that is, quenching is performed in static water, and the D50 of the obtained initial particles is 3-5 mm.

[0100] The mechanical tests and transmittance tests were carried out on the prepared light-cured additively manufactured high-transmittance lithium disilicate glass-ceramic crown, and the results showed that its flexural strength was 285 MPa, hardness was 5 GPa, and transmittance was 30%.

[0101] Comparative Example 2

[0102] In this comparative example, a method for manufacturing highly transparent lithium disilicate glass ceramics by photocuring additive manufacturing is used. The preparation process and other parameters are the same as those in Example 3, except that:

[0103] The sintered sample obtained in step S9 is used as a dental crown product, that is, the ion exchange in step S10 is not performed.

[0104] The mechanical tests and transmittance tests were performed on the prepared light-cured additively manufactured high-transmittance lithium disilicate glass-ceramic crowns, and the flexural strength was 400 MPa, the hardness was 7 GPa, and the transmittance was 50%.

[0105] In summary, it can be seen from the above embodiments and comparative examples that under the conditions of deionized water at a specific flow rate and temperature and degreasing and sintering, the preparation method of the present application can optimally obtain a lithium disilicate glass-ceramic crown with a flexural strength of 530 MPa, a hardness of 8 GPa, and a transmittance of 50%, which fully meets the theoretical and practical application requirements.

[0106] Those skilled in the art will understand that the foregoing descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will be able to modify the technical solutions described in the foregoing embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for photocuring additive manufacturing of highly transparent lithium disilicate glass ceramics, characterized in that: include: S1. Prepare a powder according to the following components in percentage by mass: 59% to 70% SiO2, 14% to 20% Li2O, 3% to 5% K2O, 1% to 5% P2O5, 1% to 3% ZnO and other components, wherein the other components include Al2O3, ZrO2, Na2O, Tb4O7, La2O3, CeO2, MgO, Y2O3, and CaO; S2, adding anhydrous ethanol to the powder, mixing uniformly by ball milling, drying, and then heat treating to obtain a molten mixture; S3, dropping the molten mixture into deionized water in a stable flow state to quench it, forming initial particles in the deionized water, wherein D50 of the initial particles is ≤1 mm; S4, ball-milling and sieving the initial particles to prepare a powder with a particle size of D50 = 0.3-0.5 μm, and then granulating the powder by spray drying to obtain lithium disilicate glass ceramic particles with a size of 5-25 μm; S5, mixing the photosensitive resin premix, dispersant, and photoinitiator to obtain a resin mixture; S6, adding the lithium disilicate glass ceramic particles obtained in step S4 to the resin mixture in multiple portions, placing the mixture in a roller press and rolling it at least once to obtain a rolled mixture, adding nano-fumed silica to the rolled mixture to obtain a paste, and placing the paste in a vacuum machine for vacuum degassing; S7, placing the paste into an additive manufacturing device for light-curing forming to obtain a green body; S8, cleaning the green body with a flowing cleaning solution, and then drying; S9, degreasing and sintering: Degreasing the green body in vacuum or inert gas: the temperature is first raised from room temperature to 200°C at a heating rate of 1°C / min, then successively raised from 200°C to 400°C at a heating rate of 0.5°C / min, and from 400°C to 500°C at a heating rate of 1°C / min, and kept at 500°C for 2 hours; then, air is introduced, the temperature is raised from 500°C to 600°C at a heating rate of 2°C / min, kept at this temperature for 1 hour, and then lowered to room temperature at a cooling rate of 2°C / min to obtain a degreased sample; The degreased sample is placed in a 21% to 24% lithium polysilicate solution for vacuum impregnation. After the predetermined impregnation time is completed, sintering is performed: heating to 500°C in air, then evacuating with the vacuum degree controlled below 10 mbar, and then heating to 630°C, holding the temperature for 2 hours, then heating to 800 to 950°C at a heating rate of 2°C / min, holding the temperature for 1 hour, and then cooling to room temperature at a rate of 2°C / min to obtain a sintered sample; S10, ion exchange: placing the sintered sample in a high-pressure vacuum furnace in a flowing nitrate under the action of a stirring device, heating to 300-600°C under vacuum conditions, immersing the sintered sample in the molten nitrate to undergo an ion exchange reaction therewith, the reaction time being 0.5-2 hours, and finally obtaining the product; the nitrate is a mixture of sodium nitrate and rubidium nitrate in a mass ratio of 1:

1.

2. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: In step S3, the temperature of the deionized water is 20-25° C., and the flow rate is 0.5-2 m / s.

3. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: In step S4, the particle size of the lithium disilicate glass ceramic particles of 5 to 25 μm presents a bimodal distribution, with two peaks at 5 μm and 25 μm, respectively.

4. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: In step S6, the mass of the lithium disilicate glass ceramic particles accounts for 70% to 85% of the paste, the mass of the nano-fumed silica accounts for 0.1% to 0.5% of the paste, and the particle size of the nano-fumed silica is 7 nanometers.

5. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: The photosensitive resin premix comprises a monofunctional photosensitive resin monomer, a bifunctional photosensitive resin monomer and a trifunctional photosensitive resin monomer in a mass ratio of 1:1:1 to 1:2:3; The monofunctional photosensitive resin monomer includes one or more of hydroxyethyl methacrylate, lauryl acrylate, isobornyl acrylate, phenoxyethyl acrylate, and lauric acid methacrylate; The bifunctional photosensitive resin monomer includes one or more of 1,6-hexanediol diacrylate, tripropylene glycol diacrylate, and dipropylene glycol diacrylate; The trifunctional photosensitive resin monomer includes propoxylated glycerol triacrylate or ethoxylated trimethylolpropane triacrylate.

6. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: The mass of the photoinitiator accounts for 0.5% to 2% of the mass of the photosensitive resin premix; The photoinitiator includes one or both of diphenyl 2,4,6-trimethylbenzoylphosphine oxide and 1-hydroxycyclohexyl phenyl ketone; The mass ratio of diphenyl 2,4,6-trimethylbenzoylphosphine oxide to 1-hydroxycyclohexyl phenyl ketone is 1:

1.

7. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: The dispersant includes gamma-methacryloxypropyltrimethoxysilane and gamma-glycidoxypropyltrimethoxysilane in a mass ratio of 1:

1.

8. The method for manufacturing highly transparent lithium disilicate glass ceramics by photocuring additive manufacturing according to claim 1, characterized in that: In step S7, the cleaning solution includes hexanediol diacrylate, isopropyl alcohol and polyethylene glycol 200 in a mass ratio of 1:1:

1.

9. The method for manufacturing highly transparent lithium disilicate glass ceramics by light-curing additive manufacturing according to claim 1, characterized in that: In step S2, the temperature of the heat treatment is 1400-1600°C.

10. A lithium disilicate glass ceramic prepared by the method for manufacturing highly transparent lithium disilicate glass ceramic by light-curing additive manufacturing according to any one of claims 1 to 9, characterized in that: The lithium disilicate glass ceramic has a flexural strength of 480-530 MPa, a hardness of 6-8 GPa, and a light transmittance of 40%-50%.

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