Embedded connection modular photocuring 3D ceramic printing method

Abstract

The invention relates to a method for photocuring 3D printing ceramic, in particular to an embedded connection modularized photocuring 3D printing ceramic method. The method aims at solving the technical problem that block 3D printing of the ceramic part cannot be achieved through an existing method. The method comprises the following steps: splitting a 3D model of a target large-size structure into structure modules in embedded connection on a computer by using software, and importing the 3D model of each structure module into a DLP printer; the preparation method comprises the following steps: preparing ceramic slurry from an acrylate monomer, polymerized acrylate, monofunctional polyurethane acrylate, ceramic powder, a dispersing agent and a photoinitiator, printing each structural module by using the slurry, cleaning and airing each structural module, and dropwise adding n-butyl acetate on a connection interface of an embedded structure to connect a plurality of modules into a whole, so as to obtain the embedded structure. And degreasing and sintering at high temperature to obtain the 3D printing ceramic. According to the method, interface welding is accurate, the printing cost can be reduced, cross-space-time printing can be achieved, and the method can be applied to the field of 3D ceramic printing.

Description

Technical Field

[0001] The invention relates to a method for photocuring 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 improves the freedom of ceramic material design and manufacturing. However, the size and printing speed of ceramic parts formed by current photocuring 3D printing technology are limited by the size 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 one 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 is required, or complex functional unit modifications are required. The corresponding equipment cost is extremely high and not universal.

[0003] At present, for larger-sized 3D printed parts, a block printing method can be used. For example, the Chinese patent "Sanitary ceramic mold forming method based on three-dimensional printing technology" with application number CN201610497849.3 discloses a method of first dividing the 3D model into blocks through a three-dimensional printer, and then printing the blocks; then polishing and smoothing all the parts one by one, and then using adhesives to bond and assemble them into a plastic solid model, and then batch-producing to obtain a sanitary ceramic mold. The Chinese patent "Method for 3D printing large sculpture models" with application number 201711153154.4 discloses a method of first using ordinary printing equipment to print thin models in blocks, and then bonding and assembling the assembly surfaces with slow-drying resin glue. However, the existing methods that rely on adhesives cannot achieve block 3D printing of ceramic parts, because the printed parts (green bodies) of ceramic parts need to go through 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 body will decompose due to heat during the degreasing and sintering process, causing the assembly interface to separate, and thus it is impossible to obtain an integrated ceramic material. Summary of the invention

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

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

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

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

[0008] 3. Injecting ceramic slurry into the material tank of the DLP printer, starting printing, and performing photocuring printing on each module to obtain green sheets of multiple modules; the ceramic slurry used to print each green sheet is the same or different;

[0009] 4. Remove the module green body on the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate on the connection interface of the module embedded structure, and apply pressure on both sides of the interface to make the module 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, so as to connect multiple modules into one, and 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 for 2-5 hours, then heat it to 150-155°C and keep it for 2-5 hours, and finally heat it to 600-620°C and keep it for 2-5 hours for degreasing; then sinter it at high temperature to obtain 3D printed ceramics.

[0011] Furthermore, the acrylic acid ester monomer described 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% of the mass of the acrylate monomer to the acrylate monomer, mixing evenly, and performing photocuring 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 keep the polymer in a certain microscopic tight connection through hydrogen bonds before polymerization, thereby improving its reaction activity 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 accuracy of ceramic printing is inversely proportional to the light energy intensity and irradiation time, so the addition of monofunctional polyurethane acrylate can effectively improve the printing accuracy; in addition, because the added material is monofunctional, there is no additional cross-linking point, so that the polymerization reaction is still a linear polymerization reaction, thereby ensuring the rapid gelation of the interface during the welding process and the 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 aluminum oxide or zirconium oxide 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 ceramic slurry after mixing.

[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 sintering at a temperature of 1450-1500°C for 1-3 hours for zirconia ceramics.

[0020] The present invention utilizes n-butyl acetate to wet and stimulate the connection interface of 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, and a gel layer structure with certain fluidity is formed at the interface. Under external pressure, the two gel layers at the connection interface undergo mutual diffusion movement. With the mutual diffusion and solvent evaporation, a new bonding surface is formed at the connection, thereby realizing a body 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 ceramic material method of the present invention is a low-cost, high-efficiency photocurable 3D printing method for forming large-size ceramics. It is based on a ceramic printing slurry prepared with a solvent-responsive high molecular polymer resin as a substrate, and uses a DLP printer to print and form multiple ceramic green modules with embedded structures. The surface of the embedded structure of the green module is activated by solvent stimulation, so that the ceramic green modules are welded as a whole, and after degreasing and sintering processes, an integrated ceramic material with a complete structure is obtained. The present invention breaks through the problem that the size of photocurable 3D printed samples is limited by the scale of the printer, and uses a lower-cost modular printing and construction method, which has the following advantages and beneficial effects:

[0022] 1. Breaking through the size limitation of photocuring printers, making them capable of cross-size printing. Large-size ceramic structures can be split into multiple modules for batch printing, so that a photocuring printer can form ceramic materials that exceed its printing size range by printing modules.

[0023] 2. Realize low-cost photocuring printing of large-size ceramic devices. Since large devices can be spliced ​​and formed by multiple modules in a chimeric connection manner, the ceramic modules after chimeric connection can maintain extremely high strength and stability at the connection. And the printed modules can be stored for a long time, so one printer can be used to print all modules multiple times, or multiple ceramic modules can be obtained in one printing process.

[0024] 3. By improving the slurry formula and adding long-chain monofunctional polyurethane acrylate components, the printing accuracy of the slurry is improved, so that high-precision printing of connection structures that need to fit together perfectly can be achieved, making it possible to make interlocking connections between modules;

[0025] 4. Realize the cross-time and space cooperation capability of ceramic printing. Different modules of the same ceramic material can be printed by printers distributed in different locations at different times, and then the printed green modules are sealed and stored and sent to the same place for connection, followed by degreasing and sintering to obtain an integrated ceramic material.

[0026] 5. Improve the fault tolerance of ceramic photocuring printing. The traditional method has a very low fault tolerance rate for printing larger ceramic materials. Once defects or equipment problems occur during the printing process, the entire print will be scrapped. Large-size ceramic printing is prone to problems due to its quality and size structure. With the modular method, only the specific printing module needs to be replaced or reset, which greatly improves the fault tolerance of the printing process and reduces the printing cost accordingly.

[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 during 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 This is a schematic diagram of the preparation process of the present invention: wherein 1 represents 3D printing, 2 is the first module, 3 is the second module, 4 is n-butyl acetate, and 5 is a ceramic product. DETAILED DESCRIPTION

[0030] The beneficial effects of the present invention are verified by the following examples.

[0031] The beneficial effects of the present invention are verified by the following examples.

[0032] Embodiment 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 a 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 shown in the figure are used to import the 3D models of the first module 2 and the second module 3 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 dispersant BYK, 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, the mixture is evenly mixed, and then photocured 3D printing is performed using DLP printing to obtain polymerized isobornyl acrylate;

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

[0038] 4. Remove the module blank on the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate on 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 keep 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 a 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] In this comparative example, polymerized isobornyl acrylate is not added, and the prepared ceramic slurry will undergo severe sedimentation within 2 hours and cannot be used for ceramic printing. This is because polymerized isobornyl acrylate is dissolved in isobornyl acrylate monomer, and its dissolution method is that the molecular chain of polymerized isobornyl acrylate is evenly dispersed in the monomer, so that the system becomes 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 ceramic powder in the system and form a stable slurry system. In this comparative example, 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 acrylate in step 2 is replaced by 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 connecting surface of the mosaic structure of the printed first module 2 and the second module 3 is low, and the connecting structure cannot be accurately embedded, indicating 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 mosaic structures that require high precision to be connected to each other, thereby ensuring the welding quality.

[0045] Comparative Example 3: This comparative example is different 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 Example 1.

[0046] The monofunctional polyurethane acrylate added in this comparative example is excessive. 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 bonding 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, which makes interface gelation difficult during the interface welding process and seriously weakens the interface welding ability.

[0047] Embodiment 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 a 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 shown in the figure are used to import the 3D models of the first module 2 and the second module 3 into the DLP printer; the embedded connection

[0049] 2. Preparation of ceramic slurry:

[0050] Weigh 100 g of isobornyl acrylate monomer, 4 g of polymerized isobornyl acrylate, 20 g of monofunctional polyurethane acrylate, 500 g of zirconium oxide ceramic powder, 10 g of dispersant BYK, and 0.3 g of 819 photoinitiator, add them into a ball mill, and ball mill them 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, the mixture is evenly mixed, and then photocured 3D printing is performed using DLP printing to obtain polymerized isobornyl acrylate;

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

[0053] Fourth, remove the module green body on the printing platform, and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate on 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 keep it for 10 minutes, then remove the pressure, let it stand for 8 hours, so that the contact surface will continue to promote interface welding under the mosaic structure, connect multiple modules into one, connect two modules into one, and 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. Use software on a computer to split the 3D model of the target large-size structure into structural modules with embedded connections, and import the 3D models of each structural module into a DLP printer; the embedded connection is a mortise and tenon structural connection or a Lego-style structural connection; 2. Prepare ceramic slurry: weigh acrylate monomer, polymerized acrylate, monofunctional polyurethane acrylate, ceramic powder, dispersant, photoinitiator and add them into 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. Inject the ceramic slurry into the material tank of the DLP printer, start printing, and perform photocuring 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 on the printing platform and clean the residual slurry on the surface of the module with water; after cleaning and drying, apply n-butyl acetate on the connection interface of the module embedded structure, and apply pressure on both sides of the interface to make the module 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, so as to connect multiple modules into one, and 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 for 2-5 hours, then heat it to 150-155°C and keep it for 2-5 hours, and finally heat it to 600-620°C and keep it 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 acrylic acid ester monomer described 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 monomers using a DLP printer.

4. A 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. A 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. A 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. A method for embedded connection modular light-curing 3D printing ceramics according to claim 1 or 2, characterized in that: The photoinitiator described 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 ceramic slurry after mixing.

9. A 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 described in step 5 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.

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