Embedded connection method for modular light-curing 3D printed ceramics

Abstract

A method for embedded connection modular photocuring 3D printing of ceramics, which relates to a method for photocuring 3D printing of ceramics. It is intended to solve the technical problem that existing methods cannot achieve block 3D printing of ceramic parts. This method: use software on a computer to split the 3D model of the target large-scale structure into embedded connected structural modules, and import the 3D model of each structural module into a DLP printer; use acrylate monomers, polymerized acrylates, monofunctional polyurethane acrylates, ceramic powders, dispersants and photoinitiators to prepare ceramic slurry, and use the slurry to print out each structural module, clean and dry each structural module, and then drip n-butyl acetate on the connection interface of the embedded structure to connect multiple modules into one, and then degrease and sinter at high temperature to obtain 3D printed ceramics. The method of the present invention has precise interface welding, can reduce printing costs and realize cross-time and space printing, and can be used in the field of 3D printing ceramics.

Description

Technical Field

[0001] The invention relates to a method for light-curing 3D printing ceramics. Background Art

[0002] 3D printed ceramics is a technology that prepares ceramic materials by building them up layer by layer. It has the ability to flexibly form complex precision ceramic structures. Compared with traditional ceramic processing technologies that rely on mold forming, it fully enhances the degree of freedom in the design and manufacture of ceramic materials. However, the size and printing speed of ceramic parts formed by current photocuring 3D printing technology are limited by the scale and work efficiency of the printer, and it has obvious single-device working characteristics, that is, the forming of a ceramic material is completely undertaken by a single device independently, which greatly reduces the work efficiency of photocuring 3D printed ceramics. In addition, for the photocuring 3D printing of large-sized ceramic parts, either corresponding large-sized printing equipment or complex functional unit modification is required. The corresponding equipment cost is extremely high and does not have universal applicability.

[0003] Currently, for larger 3D-printed parts, a block-by-block printing method can be used. For example, Chinese patent application number CN201610497849.3, "Method for Forming Sanitary Ceramic Molds Based on 3D Printing Technology," discloses a method that first divides a 3D model into blocks using a 3D printer and then prints each block. Each block is then polished and smoothed, and then bonded together with adhesive to form a plastic solid model. This is then used to mass-produce sanitary ceramic molds. Chinese patent application number 201711153154.4, "Method for 3D Printing Large Sculpture Models," discloses a method that uses conventional printing equipment to print a thin model in blocks, and then bonds the assembled surfaces together with slow-drying resin glue. However, existing methods that rely on adhesives cannot achieve block-by-block 3D printing of ceramic parts, because the printed parts (green parts) of ceramic parts need to undergo high-temperature degreasing and sintering to become ceramics. The highest temperature of the process generally reaches 1500-2000°C. The adhesive or resin glue used to bond the interface of the green parts decomposes due to heat during the degreasing and sintering process, causing the assembly interface to separate, making it impossible to obtain an integrated ceramic material. Summary of the Invention

[0004] The present invention aims to solve the technical problem that existing methods cannot achieve block 3D printing of ceramic parts, and provides a method for embedded connection modular light-curing 3D printing of ceramics.

[0005] The method for embedded connection modular light-curing 3D printing ceramics of the present invention comprises the following steps:

[0006] 1. Using software on a computer, split the 3D model of the target large-scale structure into structural modules with embedded connections, and import the 3D models of each structural module into a DLP printer; the embedded connections are mortise and tenon structural connections or Lego-style structural connections;

[0007] 2. Prepare ceramic slurry: Weigh acrylate monomer, polymerized acrylate, monofunctional polyurethane acrylate, ceramic powder, dispersant, and photoinitiator and add them to a ball mill and mix them evenly to obtain ceramic slurry; the mass of polymerized acrylate is 3% to 15% of the mass of acrylate monomer;

[0008] 3. Pour the ceramic slurry into the material tank of the DLP printer, start printing, and perform light-curing printing on each module to obtain a plurality of module green bodies; the ceramic slurry used to print each green body is the same or different;

[0009] 4. Remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface of the module embedded structure, and apply pressure on both sides of the interface to make the modules fit together, and keep it for 10 to 30 minutes. Then remove the pressure and let it stand for 6 to 8 hours, so that the contact surface will continue to promote interface welding under the fitting structure by self-pressure, thereby connecting multiple modules into one to obtain an integrated prefabricated blank;

[0010] 5. Place the integrated preform into a sintering furnace, heat it to 120-125°C at a heating rate of 0.2-2°C / min and keep it warm for 2-5 hours, then heat it to 150-155°C and keep it warm for 2-5 hours, and finally heat it to 600-620°C and keep it warm for 2-5 hours for degreasing; then sinter it at high temperature to obtain 3D printed ceramics.

[0011] Furthermore, the acrylate monomer in step 2 is isobornyl acrylate, isobornyl methacrylate, neobornyl acrylate, neobornyl methacrylate or isobornyl diester acrylate.

[0012] Furthermore, the preparation method of the polymerized acrylate described in step 2 is: adding a photoinitiator accounting for 0.3% to 8% by mass of the acrylate monomer to the acrylate monomer, mixing evenly, and performing light-curing 3D printing with a DLP printer to obtain the polymerized acrylate.

[0013] Furthermore, the amount of monofunctional polyurethane acrylate added in step 2 is 10% to 20% of the mass of the acrylate monomer. Because monofunctional polyurethane acrylate has a large number of hydrogen bonds, it can maintain a certain microscopic tight connection through hydrogen bonds before polymerization occurs, thereby improving its reactivity during the polymerization process and achieving a faster and more reactive polymerization effect under lower and shorter light energy radiation. At the same time, the precision of ceramic printing is inversely proportional to the light energy intensity and irradiation time. Therefore, the addition of monofunctional polyurethane acrylate can effectively improve printing accuracy. In addition, because the added material is monofunctional, there are no additional cross-linking points, so the polymerization reaction remains a linear polymerization reaction, thereby ensuring rapid gelation of the interface during the welding process and mutual diffusion driven by the molecular chain. The addition amount of monofunctional polyurethane acrylate is controlled at 10% to 20% of the resin mass because the hydrogen bonding effect of the polyurethane material makes the polymer after polymerization have an attractive binding effect between chains similar to the cross-linking effect. If the content of polyurethane acrylate is too much, the hydrogen bonding effect will be too strong, causing the polymer after polymerization to exhibit the characteristics of a cross-linked product, making interfacial gelation difficult during the interface welding process and seriously weakening the interface welding ability.

[0014] Furthermore, the ceramic powder in step 2 is alumina or zirconia ceramic powder.

[0015] Furthermore, the dispersant in step 2 is BYK; the mass of BYK is 1% to 5% of the mass of the ceramic powder.

[0016] Furthermore, the photoinitiator in step 2 is 819 or TPO photoinitiator; the mass of the photoinitiator is 0.3% to 8% of the sum of the mass of the acrylate monomer and the polymerized acrylate.

[0017] Furthermore, in step 2, the volume of the ceramic powder in step 1 is 40% to 50% of the total volume of the mixed ceramic slurry.

[0018] Furthermore, in step 4, n-butyl acetate is coated on the connection interface, and the coating amount of n-butyl acetate is 20 μL to 30 μL per square centimeter.

[0019] Furthermore, the high temperature sintering described in step five is sintering at a temperature of 1600-1700° C. for 1-5 hours for alumina ceramics; and at a temperature of 1450-1500° C. for 1-3 hours for zirconia ceramics.

[0020] The present invention utilizes n-butyl acetate to infiltrate and stimulate the connection interface of the two modules. Due to the extremely strong solubility of n-butyl acetate solvent for polymerized acrylate, the polymerized acrylate molecular chains at the interface are disentangled, forming a gel layer structure with a certain fluidity at the interface. Under external pressure, the two gel layers at the connection interface undergo mutual diffusion movement. As the mutual diffusion and solvent evaporation occur, a new bonding surface is formed at the connection, thereby achieving a bulk connection interface of the green material that does not rely on adhesives or other resin glues. The preparation process is as follows: Figure 1 shown.

[0021] The modular photocurable 3D printing method for ceramic materials disclosed herein is a low-cost, highly efficient method for photocurable 3D printing of large-scale ceramics. Based on a ceramic printing slurry prepared from a solvent-responsive polymer resin as a substrate, a DLP printer is used to print and form multiple ceramic green modules with embedded structures. The embedded structures of the green modules are activated by solvent stimulation, thereby welding the green modules into a whole. After degreasing and sintering, a fully integrated ceramic material is obtained. This invention overcomes the problem that the size of photocurable 3D printed samples is limited by the size of the printer. It uses a lower-cost modular printing and construction method with the following advantages and benefits:

[0022] 1. Breaking through the size limitations of stereolithography printers, enabling them to print across multiple sizes. Large ceramic structures can be split into multiple modules for batch printing, allowing a single stereolithography printer to print ceramic materials beyond its printable size range by printing these modules.

[0023] 2. Enables low-cost, photocurable printing of large-scale ceramic components. Because large components can be assembled from multiple modules using a chiseled connection, the chiseled ceramic modules maintain exceptional strength and stability at the joints. Furthermore, the printed modules can be stored for long periods of time, allowing multiple prints to be completed using a single printer, or multiple ceramic modules to be produced in a single print run.

[0024] 3. By improving the slurry formula and adding long-chain monofunctional polyurethane acrylate components, the printing accuracy of the slurry is improved, thereby enabling high-precision printing of connection structures that require seamless interlocking, making interlocking connections between modules possible;

[0025] 4. Achieve cross-temporal collaboration in ceramic printing. Different modules of the same ceramic material can be printed at different times by printers in different locations. The printed green modules are then sealed and sent to the same location for connection, followed by debinding and sintering to create an integrated ceramic material.

[0026] 5. Improve the fault tolerance of photocurable ceramic printing. Traditional methods have a very low tolerance for printing larger ceramic materials. If a defect or equipment problem occurs during the printing process, the entire print will be scrapped. Large-scale ceramic printing is prone to problems due to its quality and size structure. Using a modular approach, only the specific printing module needs to be replaced or reset, greatly improving the fault tolerance of the printing process and correspondingly reducing printing costs.

[0027] 6. The design of the embedded connection structure can improve the accuracy of the welding interface during the solvent welding step, and avoid the interface defect problem caused by inaccurate interface bonding due to manual welding. At the same time, the interface after welding is fixed by the embedded structure, which can ensure that in the subsequent movement and degreasing sintering process, the interface is subjected to the extrusion force of the structural rigidity, which is conducive to overcoming the generation of micro-defects inside the interface and improving the mechanical properties of the interface joint.

[0028] The method of the present invention can be used in the field of 3D printing ceramics. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the preparation process of the present invention: 1 represents 3D printing, 2 represents the first module, 3 represents the second module, 4 represents n-butyl acetate, and 5 represents the ceramic product. DETAILED DESCRIPTION

[0030] The beneficial effects of the present invention are demonstrated with the following examples.

[0031] The beneficial effects of the present invention are demonstrated with the following examples.

[0032] Example 1: The embedded connection modular light-curing 3D printing ceramic method of this embodiment is carried out according to the following steps:

[0033] 1. Use software on the computer to split the 3D model of the target large-scale structure into interconnected embedded connection modules, such as Figure 1 The first module 2 and the second module 3 are shown, and the 3D models of the first module 2 and the second module 3 are imported into the DLP printer; the embedded connection

[0034] 2. Preparation of ceramic slurry:

[0035] Weigh 100 g of isobornyl acrylate monomer, 3 g of polymerized isobornyl acrylate, 20 g of monofunctional polyurethane acrylate, 500 g of alumina ceramic powder, 10 g of BYK dispersant, and 0.3 g of 819 photoinitiator, add them into a ball mill at room temperature, and ball mill for 4 h to obtain a ceramic slurry;

[0036] The preparation method of polymerized isobornyl acrylate is as follows: 0.5 g of TPO photoinitiator is added to 100 g of isobornyl acrylate, mixed evenly, and then photocured 3D printed using DLP printing to obtain polymerized isobornyl acrylate;

[0037] 3. Pour the ceramic slurry into the material tank of the DLP printer, start it, and perform light-curing printing on the first module 2 and the second module 3 to obtain the green bodies of the two modules;

[0038] 4. Remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface of the mosaic structure of the first module 2 and the second module 3, then mosaic the connection, and apply pressure on both sides of the interface by hand to make the interface close and maintain it for 10 minutes, then remove the pressure and let it stand for 8 hours, so that the contact surface will continue to promote interface welding under the mosaic structure, and connect the two modules into one to obtain an integrated prefabricated blank;

[0039] 5. Place the integrated preform into a sintering furnace, heat it to 120°C at a heating rate of 1°C / min and keep it for 2 hours, then heat it to 150°C and keep it for 2 hours, and finally heat it to 600°C and keep it for 2 hours for degreasing; then heat it to 1600°C and sinter it at high temperature for 2 hours to obtain a 3D printed alumina ceramic product.

[0040] The connection surface of the 3D printed alumina ceramic product obtained in this Example 1 has the same structure as the module body, indicating that the welding is good.

[0041] Comparative Example 1: This comparative example differs from Example 1 in that the polymerized isobornyl acrylate in step 2 is replaced with isobornyl acrylate monomer, and the other steps and parameters are the same as those in Example 1.

[0042] This comparative example does not add polymerized isobornyl acrylate, and the prepared ceramic slurry will experience severe sedimentation within 2 hours and cannot be used for ceramic printing. This is because the polymerized isobornyl acrylate is dissolved in the isobornyl acrylate monomer, and its dissolution method is that the molecular chains of the polymerized isobornyl acrylate are evenly dispersed in the monomer, thereby making the system a three-dimensional network structure. After adding ceramic powder and dispersant, a three-dimensional gel structure can be formed, which can inhibit the agglomeration and sedimentation of the ceramic powder in the system and form a stable slurry system. In this comparative example, the polymerized isobornyl acrylate is replaced with pure isobornyl acrylate monomer, and a three-dimensional network structure cannot be formed, resulting in severe sedimentation of the ceramic powder in the slurry, which cannot be used for ceramic printing.

[0043] Comparative Example 2: This comparative example differs from Example 1 in that the monofunctional polyurethane acrylic acid in step 2 is replaced with isobornyl acrylate monomer, and the other steps and parameters are the same as those in Example 1.

[0044] In this comparative example, monofunctional polyurethane acrylate is not added, and the precision of the chimeric structure connection surface of the printed first module 2 and the second module 3 is low, and the connection structure cannot be accurately embedded. This shows that the addition of monofunctional polyurethane acrylate can effectively improve the printing precision of the slurry and improve the printing quality of the slurry. Therefore, it is also possible to realize the printing of chimeric structures that require high precision to connect with each other and ensure the welding quality.

[0045] Comparative Example 3: This comparative example differs from Example 1 in that the amount of monofunctional polyurethane acrylate added in step 2 is modified to 30 g, and the other steps and parameters are the same as those in Example 1.

[0046] The monofunctional polyurethane acrylate added in this comparative example exceeds the amount. When the printed first module 2 and the second module 3 are connected together, it takes 30 minutes to weld the first module 2 and the second module 3 together. The welding time is long. This is because the hydrogen bonding effect of the polyurethane material makes the polymer after polymerization have an attractive binding effect between chains similar to the cross-linking effect. When the content of polyurethane acrylate is too high, the hydrogen bonding effect is too strong, causing the polymer after polymerization to exhibit the characteristics of a cross-linked product, making interface gelation difficult during the interface welding process and seriously weakening the interface welding ability.

[0047] Example 2: The embedded connection modular light-curing 3D printing ceramic method of this embodiment is carried out according to the following steps:

[0048] 1. Use software on the computer to split the 3D model of the target large-scale structure into interconnected embedded connection modules, such as Figure 1 The first module 2 and the second module 3 are shown, and the 3D models of the first module 2 and the second module 3 are imported into the DLP printer; the embedded connection

[0049] 2. Preparation of ceramic slurry:

[0050] 100 g of isobornyl acrylate monomer, 4 g of polymerized isobornyl acrylate, 20 g of monofunctional polyurethane acrylate, 500 g of zirconia ceramic powder, 10 g of BYK dispersant, and 0.3 g of 819 photoinitiator were weighed and added to a ball mill, and ball milled at room temperature for 4 h to obtain ceramic slurry 2;

[0051] The preparation method of polymerized isobornyl acrylate is as follows: 0.5 g of TPO photoinitiator is added to 100 g of isobornyl acrylate, mixed evenly, and then photocured 3D printed using DLP printing to obtain polymerized isobornyl acrylate;

[0052] 3. Pour the ceramic slurry into the material tank of the DLP printer, start it, and perform light-curing printing on the first module 2 and the second module 3 to obtain the green bodies of the two modules;

[0053] Fourth, remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface of the mosaic structure of the first module 2 and the second module 3, then mosaic the connection, and apply pressure on both sides of the interface by hand to make the interface close and maintain it for 10 minutes, then remove the pressure and let it stand for 8 hours, so that the contact surface will continue to promote interface welding under the mosaic structure by self-pressure, connect multiple modules into one, and connect two modules into one to obtain an integrated prefabricated blank;

[0054] 5. Place the integrated preform into a sintering furnace, heat it to 120°C at a heating rate of 1°C / min and keep it for 2 hours, then heat it to 150°C and keep it for 2 hours, and finally heat it to 600°C and keep it for 2 hours for degreasing; then heat it to 1450°C and sinter it for 3 hours to obtain a 3D printed zirconia ceramic product.

[0055] The connection surface of the 3D printed zirconia ceramic product obtained in this Example 2 has the same structure as the module body, indicating that the welding is good.

Claims

1. A method for embedded connection modular light-curing 3D printing ceramics, characterized in that The method proceeds as follows:

1. Using software on a computer, split the 3D model of the target large-scale structure into structural modules with embedded connections, and import the 3D models of each structural module into a DLP printer; the embedded connections are mortise and tenon structural connections or Lego-style structural connections; 2. Prepare ceramic slurry: weigh acrylate monomer, polymerized acrylate, monofunctional polyurethane acrylate, ceramic powder, dispersant, and photoinitiator and add them to a ball mill and mix them evenly to obtain ceramic slurry; The mass of the polymerized acrylate is 3% to 15% of the mass of the acrylate monomer; 3. Pour the ceramic slurry into the material tank of the DLP printer, start printing, and perform light-curing printing on each module to obtain a green body of multiple modules; The ceramic slurry used to print each green body is the same or different; 4. Remove the module green body from the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate to the connection interface of the module embedded structure, and apply pressure on both sides of the interface to make the modules fit together, and keep it for 10 to 30 minutes. Then remove the pressure and let it stand for 6 to 8 hours, so that the contact surface will continue to promote interface welding under the fitting structure by self-pressure, thereby connecting multiple modules into one to obtain an integrated prefabricated blank; 5. Place the integrated preform into a sintering furnace, heat it to 120-125°C at a heating rate of 0.2-2°C / min and keep it warm for 2-5 hours, then heat it to 150-155°C and keep it warm for 2-5 hours, and finally heat it to 600-620°C and keep it warm for 2-5 hours for degreasing; then sinter it at high temperature to obtain 3D printed ceramics.

2. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1, characterized in that: The acrylate monomer in step 2 is isobornyl acrylate, isobornyl methacrylate, neobornyl acrylate, neobornyl methacrylate or isobornyl diester acrylate.

3. A method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The polymerized acrylate described in step 2 is obtained by printing acrylate monomer using a DLP printer.

4. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The amount of the monofunctional polyurethane acrylate added in step 2 is 10% to 20% of the mass of the acrylate monomer.

5. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The ceramic powder in step 2 is aluminum oxide or zirconium oxide ceramic powder.

6. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The dispersant described in step 2 is BYK; the mass of BYK is 1% to 5% of the mass of the ceramic powder.

7. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The photoinitiator in step 2 is 819 or TPO photoinitiator; the mass of the photoinitiator is 0.3% to 8% of the sum of the mass of the acrylate monomer and the polymerized acrylate.

8. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The volume of the ceramic powder in step 2 is 40% to 50% of the total volume of the mixed ceramic slurry.

9. The method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: In step 4, n-butyl acetate is coated on the connection interface, and the coating amount of n-butyl acetate is 20 μL to 30 μL per square centimeter.

10. The method for embedded connection modular light-curing 3D printing ceramics according to claim 4, characterized in that: The high temperature sintering in step 5 is performed at a temperature of 1600-1700° C. for 1-5 hours for alumina ceramics; and at a temperature of 1450-1500° C. for 1-3 hours for zirconia ceramics.

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