Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and its preparation method

Abstract

The present invention relates to the field of 3D printing materials and discloses a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and its preparation method. The components include potassium sodium niobate powder modified with a coupling agent, a radical photosensitive resin, a diluent, a radical initiator, a dispersant, an anti-settling agent, an anti-foaming agent, and a toner. The radical photosensitive resin includes difunctional, trifunctional, and hexafunctional aliphatic polyurethane acrylates. The present invention selects a specific radical photosensitive resin and combines it with a diluent to achieve a slurry with high solids content, low viscosity, good flowability, and fast curing reaction rate, meeting the needs of high-speed printing. The potassium sodium niobate powder is modified with a coupling agent, and the combination with a dispersant and an anti-settling agent significantly reduces the powder's settling rate and extends the shelf life of the slurry. The addition of an adhesion promoter and toner improves printing accuracy, increases the compactness of the sintered product, and improves piezoelectric performance.

Description

[Technical Field]

[0001] The present invention relates to the technical field of 3D printing materials, and in particular to a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and its preparation method. [Background technology]

[0002] Lead-based piezoelectric ceramics contain high concentrations of lead, which is extremely harmful to the environment and human health, and are gradually being restricted by laws in various countries. Therefore, environmentally friendly lead-free piezoelectric ceramics, especially potassium sodium niobate (KNN)-based ceramics, are attracting attention because they have a large piezoelectric coefficient, a high Curie temperature, and performance comparable to that of lead zirconate titanate.

[0003] Currently, the development and manufacture of complex, high-performance piezoelectric ceramic components has attracted considerable attention in various fields. However, traditional manufacturing methods have difficulty achieving one-step fabrication of complex shapes. Furthermore, subtractive manufacturing, a secondary process, is prone to defects in piezoelectric ceramics, which have high strength, hardness, and brittleness, affecting their usability. Meanwhile, the emergence of additive manufacturing technologies such as 3D printing has brought piezoelectric materials into a new stage of development. Light-curing 3D printing technology, primarily based on DLP (Digital Light Processing), can achieve high-precision, customized, and personalized designs, providing an excellent technical means for finishing ceramic materials. Furthermore, the application of this technology to the manufacture of KNN piezoelectric ceramics can address issues such as mold dependency and the difficulty of manufacturing components with complex shapes and various functions.

[0004] Currently, several studies have been conducted on KNN-based ceramic slurries that can be used for 3D printing. For example, Chinese patent document No. 1 discloses a "method for producing potassium sodium niobate-based lead-free piezoelectric ceramics by stereolithography," and Chinese patent document No. 2 discloses a "potassium sodium niobate-based lead-free piezoelectric ceramic powder, slurry, and preparation process thereof." Both involve mixing potassium sodium niobate ceramic powder with a photoinitiator, photosensitive resin, dispersant, and defoamer to prepare a ceramic slurry, which is then subjected to stereolithography by 3D printing.

[0005] However, conventional ceramic slurries prepared by mixing potassium sodium niobate ceramic powder with a photoinitiator, photosensitive resin, dispersant, and defoamer always suffer from slow curing speeds and poor adhesion between the slurry and the molding table during printing. Furthermore, the high absorbance of KNN powder adversely affects the photocuring of the resin, resulting in poor piezoelectric performance after 3D printing. Furthermore, the ceramic powder in conventional KNN-based 3D printing slurries is prone to settling during storage, making them difficult to store. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Chinese Patent Application Publication No. 109650887 [Patent Document 1] Chinese Patent Application Publication No. 112608150 Summary of the Invention [Problem to be solved by the invention]

[0007] To address the above-mentioned problems with conventional KNN-based 3D printing ceramic slurries, the present invention provides a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and its preparation method. This method utilizes a radical-sensitive resin in combination with a diluent to achieve a slurry with high solids content, low viscosity, good fluidity, and a fast curing reaction rate, meeting the needs of high-speed printing. The potassium sodium niobate powder is modified with a coupling agent, and the combination of this with a dispersant and anti-settling agent significantly reduces the powder's settling rate, extending the shelf life of the slurry. Furthermore, the addition of an adhesion promoter and toner improves printing accuracy without affecting the viscosity of the slurry, resulting in higher compactness of the sintered product and improved piezoelectric performance. [Means for solving the problem]

[0008] To achieve the above objectives, the present invention adopts the following technical solutions:

[0009] A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, the components of which, by weight, include 50 to 75 parts of potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts of a radical photosensitive resin, 10 to 15 parts of a diluent, 1 to 2 parts of a radical initiator, 1 to 2 parts of a dispersant, 0.5 to 1.5 parts of an anti-settling agent, 0.3 to 1 part of an anti-foaming agent, 0.1 to 1 part of an adhesion promoter, and 0.1 to 1 part of a toner; the radical photosensitive resin contains a difunctional aliphatic polyurethane acrylate, a trifunctional aliphatic polyurethane acrylate, and a hexafunctional aliphatic polyurethane acrylate in a mass ratio of 3 to 5:1 to 3:1; the diluent is selected from at least one of 1,6-hexanediol diacrylate, isobornyl acrylate, and tripropylene glycol diacrylate; the anti-settling agent is at least one of a titanate ester coupling agent, BYK-410; the adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate, hydroxyethyl methacrylic acid phosphate, and CD9051; The toner is a liquid nano white UV pigment.

[0010] The type and functionality of the radical photosensitive resin and diluent significantly affect the 3D printing performance of the slurry. Higher resin functionality leads to faster slurry curing speeds and higher molding strength, but also leads to a more rapid increase in post-cure shrinkage, resulting in excessive loss of precision and the occurrence of whiteout. To improve the printing performance of the slurry, the present invention selects a specific proportion of di-, tri-, or hexa-functional fatty polyurethane acrylate as the radical photosensitive resin and a low-functional diluent to adjust the viscosity, which is advantageous for controlling shrinkage during curing. By adding and using certain types of auxiliary agents such as anti-settling agents, adhesion promoters, and toners in the system composed of the radical photosensitive resin and diluent of the present invention, the resulting slurry has a high solids content, low viscosity, good fluidity, a fast curing reaction rate, and a low post-cure compressibility, thereby meeting the needs of high-speed printing.

[0011] Because the slurry is a suspension, the powder is prone to settling. In this invention, the potassium sodium niobate powder is surface-modified using a coupling agent to impart greater steric hindrance. Furthermore, by combining it with a dispersant and a specific anti-settling agent, the settling rate of the powder can be effectively reduced to less than 5% over 30 days, significantly extending the shelf life of the slurry. In this invention, the impact of the anti-settling agent on the viscosity of the slurry can be avoided by selecting the appropriate anti-settling agent.

[0012] Because KNN powder is gray and has high light absorption, which adversely affects the photocuring of resins, the present invention adds a toner to adjust the slurry color to a white color to enhance light absorption during 3D printing. At the same time, the present invention adds an adhesion promoter to better adhere the part to the aluminum alloy molding table during printing, increasing the success rate of sample printing. Therefore, the present invention's slurry achieves high printing accuracy, high compactness after sintering, and excellent piezoelectric performance. By utilizing the system formed by each component, the present invention can produce a photocurable KNN-based ceramic slurry with high solid loading, low shrinkage, minimal aggregation, low viscosity, slow settling, and stability.

[0013] Preferably, the radical initiator is selected from at least one of 1-hydroxycyclohexyl phenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone.

[0014] Preferably, the dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, triolein.

[0015] Preferably, the antifoaming agent is selected from at least one of silicone-based, surfactant-based, and paraffin-based antifoaming agents.

[0016] Preferably, the method for preparing the potassium sodium niobate powder modified with a coupling agent includes step A) of grinding the potassium sodium niobate powder and adding it to a mixed solution of hydrogen peroxide and absolute ethanol to react with the potassium sodium niobate hydroxide powder, and step B) of reacting the potassium sodium niobate hydroxide powder with a silane coupling agent to obtain the potassium sodium niobate powder modified with the coupling agent. The present invention uses hydrogen peroxide to activate the surface of the potassium sodium niobate powder to obtain the potassium sodium niobate hydroxide powder, which is then reacted with a silane coupling agent to obtain the potassium sodium niobate powder modified with the coupling agent, thereby reducing the specific surface area of the potassium sodium niobate powder and acting together with a dispersant and an anti-settling agent to significantly reduce the settling of the potassium sodium niobate powder.

[0017] Preferably, in step A), potassium sodium niobate powder is ground, added to a mixed solution of hydrogen peroxide and absolute ethanol, the pH of the system is adjusted to 5.5 to 6.5, and the mixture is stirred for 8 to 10 hours to react. The resulting suspension is then centrifuged and washed to obtain potassium sodium niobate hydroxide powder, and the mass ratio of the ground potassium sodium niobate powder to hydrogen peroxide and absolute ethanol is 200 to 300:30 to 40:500.

[0018] Preferably, in step A), the particle size of the potassium sodium niobate powder is 400 to 600 nm, the rotation speed during polishing is 300 to 500 r / min, and the polishing time is 1 to 2 hours.

[0019] Preferably, in step B), a silane coupling agent is added to potassium sodium niobate hydroxide powder, followed by ultrasonic treatment for 30 to 40 minutes, heating to 95 to 105°C and keeping the temperature for 1 to 2 hours, centrifuging, washing, and drying to obtain potassium sodium niobate powder modified with the coupling agent, wherein the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent is 200 to 300:2.

[0020] The present invention provides (1) preparing a potassium sodium niobate powder modified with a coupling agent; (2) uniformly mixing a radical photosensitive resin, a diluent, and a radical photoinitiator to obtain a photocurable resin mixture; The present invention further provides a method for preparing the lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, comprising step (3) adding potassium sodium niobate powder modified with a coupling agent to a photocuring resin mixture, adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter, and a toner, ball milling the mixture, and then vacuum degassing the mixture to obtain the lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing.

[0021] Preferably, the ball milling speed in step (3) is 4000 to 5000 r / min, and the ball milling time is 8 to 10 hours. [Effects of the Invention]

[0022] Therefore, the present invention has the following beneficial effects: (1) The present invention selects a specific proportion of difunctional, trifunctional, or hexafunctional fatty polyurethane acrylate as the radical photosensitive resin, and selects a low-functional diluent to adjust the viscosity. The resulting slurry has a high solid content, low viscosity, good fluidity, and a fast curing reaction speed, which can meet the needs of high-speed printing. It also has high compactness after sintering, good piezoelectric performance, and potential for future applications. (2) In the present invention, the potassium sodium niobate powder is surface-modified using a coupling agent, which gives it greater steric hindrance. In addition, by using a dispersant and a specific anti-settling agent in combination, the settling rate of the powder can be effectively reduced, with the settling rate being only 5% after 30 days, significantly extending the shelf life of the slurry. (3) The present invention adds toner to adjust the color of the slurry closer to white, thereby increasing light absorption during 3D printing and avoiding the adverse effect of the high absorbance of KNN powder on the photocuring of the resin. (4) The present invention can add an adhesion promoter to make the part better adhere to the aluminum alloy material forming table during printing, thereby increasing the success rate of sample printing. (5) The prepared DLP photocuring 3D printing lead-free potassium sodium niobate ceramic slurry of the present invention has high printing precision, which can reach 50 μm, and the formed structure does not require subsequent processing after debinding and sintering. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will now be further described with reference to specific embodiments.

[0024] In the present invention, unless otherwise specified, all equipment and materials are commercially available or commonly used in the industry, and the methods in the following examples are all conventional methods in the art unless otherwise specified.

[0025] (General embodiment) A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, the components of which, by weight, include 50 to 75 parts of potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts of a radical photosensitive resin, 10 to 15 parts of a diluent, 1 to 2 parts of a radical initiator, 1 to 2 parts of a dispersant, 0.5 to 1.5 parts of an anti-settling agent, 0.3 to 1 part of an anti-foaming agent, 0.1 to 1 part of an adhesion promoter, and 0.1 to 1 part of a toner; the radical photosensitive resin contains a difunctional aliphatic polyurethane acrylate, a trifunctional aliphatic polyurethane acrylate, and a hexafunctional aliphatic polyurethane acrylate in a mass ratio of 3 to 5:1 to 3:1; the anti-settling agent is at least one of a titanate ester coupling agent, BYK-410; the adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate (PM-1), hydroxyethyl methacrylic acid phosphate (PM-2), and CD9051; The toner is a liquid nano white UV pigment.

[0026] The diluent is selected from at least one of hexanediol diacrylate (HDDA), hydroxyethyl acrylate (HEA), isobornyl acrylate (IBOA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), pentaerythritol tetraacrylate (PETEA), trimethylolpropane triacrylate (TMPTA).

[0027] The radical initiator is selected from at least one of 1-hydroxycyclohexyl phenyl ketone (184), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester (TPO-L), 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone (659).

[0028] The dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, and triolein.

[0029] The antifoaming agent is selected from at least one of silicone-based, surfactant-based, and paraffin-based agents.

[0030] The preparation method of the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: In step (1) of preparing potassium sodium niobate powder modified with a coupling agent, potassium sodium niobate powder with a particle size of 400 to 600 nm is polished and added to a mixed solution of hydrogen peroxide and absolute ethanol. The rotation speed during polishing is 300 to 500 r / min, the polishing time is 1 to 2 hours, the mass ratio of the potassium sodium niobate powder after polishing to hydrogen peroxide and absolute ethanol is 200 to 300:30 to 40:500, the pH of the system is adjusted to 5.5 to 6.5, and the mixture is stirred and reacted for 8 to 10 hours. The resulting suspension is then centrifuged and washed to obtain potassium sodium niobate hydroxide powder. Next, a silane coupling agent is added to the potassium sodium niobate hydroxide powder, so that the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent is 200-300:2, and the mixture is subjected to ultrasonic treatment for 30-40 minutes, and then heated to 95-105°C and kept at the temperature for 1-2 hours, centrifuged, washed, and dried to obtain a potassium sodium niobate powder modified with the coupling agent (step (1)); (2) uniformly mixing a radical photosensitive resin, a diluent, and a radical photoinitiator to obtain a photocurable resin mixture; and (3) adding potassium sodium niobate powder modified with a coupling agent to the photocurable resin mixture, adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter, and a toner, ball milling the mixture at a speed of 400 to 450 r / min for 8 to 10 hours, and then vacuum degassing the mixture to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0031] Example 1 A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, the components of which, by weight, include 50 parts of potassium sodium niobate powder modified with a coupling agent, 35 parts of radical photosensitive resin, 10 parts of diluent HDDA (Shanghai Yinchang New Materials Co., Ltd.), 2 parts of radical initiator TPO (Shanghai Yinchang New Materials Co., Ltd.), 2 parts of dispersant BYK-111 (BYK-Chemie), 0.5 parts of anti-settling agent BYK-410 (BYK-Chemie), 0.5 parts of silicone defoamer (Dow Corning), 0.1 parts of adhesion promoter PM-2 (Chengdu Sicheng Photoelectric Materials Co., Ltd.), and 0.1 parts of liquid nano UV pigment (Shenzhen Xinjiayi Technology, white opaque); The radical photosensitive resin contained difunctional aliphatic polyurethane acrylate U600 (Shanghai Guangyi Chemical Co., Ltd.), trifunctional aliphatic polyurethane acrylate YC3165 (Shanghai Yinchang New Materials Co., Ltd.), and hexafunctional aliphatic polyurethane acrylate YC3620 (Shanghai Yinchang New Materials Co., Ltd.) in a mass ratio of 4:2:1.

[0032] The preparation method of the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) of preparing a potassium sodium niobate powder modified with a coupling agent, in which potassium sodium niobate powder with an average particle size of 500 nm is polished and added to a mixed solution of hydrogen peroxide and absolute ethanol. The rotation speed during polishing is 400 r / min, the polishing time is 1.5 h, and the mass ratio of the potassium sodium niobate powder to hydrogen peroxide and absolute ethanol after polishing is 300:30:500. The pH of the system is adjusted to 6.0, and the mixture is stirred at room temperature for 8 h at a rotation speed of 450 r / min to react. The resulting suspension is centrifuged and washed to obtain potassium sodium niobate hydroxide powder, and a silane coupling agent KH550 is added to the potassium sodium niobate hydroxide powder, so that the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent KH550 is 300:2. The mixture is ultrasonicated for 30 minutes, heated to 100°C and kept at the same temperature for 1 hour, centrifuged, washed, dried, and passed through a 200 mesh sieve to obtain potassium sodium niobate powder modified with the coupling agent. (1) Step (2) mixing the radical photosensitive resin, diluent and radical photoinitiator in the appropriate ratio and stirring at a rotation speed of 400 r / min for 60 minutes to obtain a photocurable resin mixture; and (3) adding potassium sodium niobate powder modified with a coupling agent to the photocurable resin mixture, and adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter, and a toner in appropriate proportions, ball milling the mixture in a B-313 planetary ball mill at a speed of 4500 r / min for 8 hours, followed by vacuum degassing to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0033] Example 2 A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, the components of which include, by weight, 75 parts of potassium sodium niobate powder modified with a coupling agent, 36.5 parts of radical photosensitive resin, 15 parts of diluent TPGDA (Shanghai Yinchang New Materials Co., Ltd.), 2 parts of radical initiator TPO (Shanghai Yinchang New Materials Co., Ltd.), 2 parts of dispersant BYK-111 (BYK-Chemie), 1.5 parts of anti-settling agent BYK-410 (BYK-Chemie), 1 part of silicone defoamer (Dow Corning), 1 part of adhesion promoter PM-2 (Chengdu Sicheng Photoelectric Materials Co., Ltd.), and 1 part of liquid nano UV pigment (Shenzhen Xinjiayi Technology, white opaque); The radical photosensitive resin contained difunctional aliphatic polyurethane acrylate U600 (Shanghai Guangyi Chemical Co., Ltd.), trifunctional aliphatic polyurethane acrylate YC3165 (Shanghai Yinchang New Materials Co., Ltd.), and hexafunctional aliphatic polyurethane acrylate YC3620 (Shanghai Yinchang New Materials Co., Ltd.) in a mass ratio of 3:3:1.

[0034] The preparation method of the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) of preparing a potassium sodium niobate powder modified with a coupling agent, in which potassium sodium niobate powder with an average particle size of 500 nm is polished and added to a mixed solution of hydrogen peroxide and absolute ethanol, the rotation speed during polishing is 400 r / min, the polishing time is 2 hours, the mass ratio of the potassium sodium niobate powder to hydrogen peroxide and absolute ethanol after polishing is 200:30:500, the pH of the system is adjusted to 6.0, and the mixture is stirred at room temperature at a rotation speed of 450 r / min for 8 hours to react, The obtained suspension is centrifuged and washed to obtain potassium sodium niobate hydroxide powder, and a silane coupling agent KH550 is added to the potassium sodium niobate hydroxide powder, so that the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent KH550 is 200:2, and the mixture is ultrasonicated for 30 minutes, heated to 100°C and kept at the same temperature for 1 hour, centrifuged, washed, dried, and passed through a 200 mesh sieve to obtain potassium sodium niobate powder modified with the coupling agent (step (1)); Step (2) mixing the radical photosensitive resin, diluent and radical photoinitiator in the appropriate ratio and stirring at a rotation speed of 400 r / min for 60 minutes to obtain a photocurable resin mixture; and (3) adding potassium sodium niobate powder modified with a coupling agent to the photocurable resin mixture, and adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter, and a toner in appropriate proportions, ball milling the mixture in a B-313 planetary ball mill at a speed of 4500 r / min for 8 hours, followed by vacuum degassing to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0035] Example 3 A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, the components of which include, by weight, 60 parts of potassium sodium niobate powder modified with a coupling agent, 30 parts of a radical photosensitive resin, 15 parts of a diluent IBOA (Shanghai Yinchang New Materials Co., Ltd.), 1 part of a radical initiator TPO (Shanghai Yinchang New Materials Co., Ltd.), 1 part of a dispersant BYK-111 (BYK-Chemie), 1.5 parts of an anti-settling agent BYK-410 (BYK-Chemie), 0.5 parts of a silicone defoamer (Dow Corning), 0.5 parts of an adhesion promoter PM-2 (Chengdu Sicheng Photoelectric Materials Co., Ltd.), and 0.5 parts of a liquid nano UV pigment (Shenzhen Xinjiayi Technology, white, opaque); The radical photosensitive resin contained difunctional aliphatic polyurethane acrylate U600 (Shanghai Guangyi Chemical Co., Ltd.), trifunctional aliphatic polyurethane acrylate YC3165 (Shanghai Yinchang New Materials Co., Ltd.), and hexafunctional aliphatic polyurethane acrylate YC3620 (Shanghai Yinchang New Materials Co., Ltd.) in a mass ratio of 5:1:1.

[0036] The preparation method of the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) of preparing a potassium sodium niobate powder modified with a coupling agent, wherein the potassium sodium niobate powder with an average particle size of 500 nm is polished and added to a mixed solution of hydrogen peroxide and absolute ethanol, the rotation speed during polishing is 400 r / min, the polishing time is 2 hours, the mass ratio of the potassium sodium niobate powder to hydrogen peroxide and absolute ethanol after polishing is 250:30:500, the pH of the system is adjusted to 6.0, and the mixture is stirred at room temperature at a rotation speed of 450 r / min for 8 hours to react, The obtained suspension is centrifuged and washed to obtain potassium sodium niobate hydroxide powder, and a silane coupling agent KH550 is added to the potassium sodium niobate hydroxide powder, so that the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent KH550 is 250:2, and the mixture is ultrasonicated for 30 minutes, heated to 100°C and kept at the same temperature for 1 hour, centrifuged, washed, dried, and passed through a 200 mesh sieve to obtain potassium sodium niobate powder modified with the coupling agent (step (1)); Step (2) mixing the radical photosensitive resin, diluent and radical photoinitiator in the appropriate ratio and stirring at a rotation speed of 400 r / min for 60 minutes to obtain a photocurable resin mixture; and (3) adding potassium sodium niobate powder modified with a coupling agent to the photocurable resin mixture, and adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter, and a toner in appropriate proportions, ball milling the mixture in a B-313 planetary ball mill at a speed of 4500 r / min for 8 hours, followed by vacuum degassing to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0037] (Comparative Example 1) Comparative Example 1 differed from Example 1 in that the radical photosensitive resin was all bifunctional aliphatic polyurethane acrylate U600, but was otherwise the same as Example 1.

[0038] (Comparative Example 2) Comparative Example 2 differs from Example 1 in that the radical photosensitive resin used was all trifunctional aliphatic polyurethane acrylate YC3165, but the rest was the same as Example 1.

[0039] (Comparative Example 3) Comparative Example 3 was different from Example 1 in that the radical photosensitive resin was all hexafunctional aliphatic polyurethane acrylate YC3620, but was otherwise the same as Example 1.

[0040] Comparative Example 4 Comparative Example 4 was the same as Example 1 except that no toner was added to the slurry.

[0041] (Comparative Example 5) Comparative Example 5 was different from Example 1 in that A-171 (Qingdao Shengshi New Materials Co., Ltd.) was used as the adhesion promoter, but the rest was the same as Example 1.

[0042] (Comparative Example 6) Comparative Example 6 was the same as Example 1 except that no anti-settling agent was added to the slurry.

[0043] (Comparative Example 7) Comparative Example 7 differed from Example 1 in that fumed silica was used as the anti-settling agent, but was otherwise the same as Example 1.

[0044] (Comparative Example 8) Comparative Example 8 was the same as Example 1 except that hydroxyethyl methacrylate (HEMA) was used as a diluent.

[0045] The performance of the slurries prepared in the above examples and comparative examples and the performance of the 3D printing ceramic materials thereof were tested, and the results are shown in Tables 1 and 2.

[0046] The viscosity of the slurry was measured using an NDJ-8S viscometer.

[0047] Sedimentation rate test method: 50 g of the slurry was sealed and stored, and the slurry was poured into a new beaker every 120 hours. The mass of the ceramic particles and the slurry deposited at the bottom of the original beaker was measured to obtain the sedimentation rate.

[0048] Testing method for slice thickness and piezoelectric performance of ceramic materials: The slurry was 3D printed using a photo-curing DLP device. The maximum exposure thickness (slice thickness) of each layer was measured, and then printed to obtain the final sample. The sample was then placed in a box furnace for debinding. It was then gradually heated at 0.15°C / min to 200°C and 400°C, held at each temperature for 3 hours, then gradually heated at 0.25°C / min to 550°C and 600°C, held at each temperature for 2.5 hours, and then naturally cooled. It was then heated at 5°C / min to 1050°C in air, held at this temperature for 4 hours, and naturally cooled to obtain the sintered KNN ceramic sample. The sintered KNN ceramic sample was coated with silver paste on both sides, dried, and then sintered at 600°C for 30 minutes. It was then heated to 120°C in silicone oil and polarized with a DC current of 3 kV / mm for 20 minutes. Its piezoelectric performance was evaluated using a quasi-static analyzer. 33 was tested.

[0049] [Table 1]

[0050] [Table 2]

[0051] As can be seen from Tables 1 and 2, the slurries prepared using the formulations and methods of the present invention in Examples 1 to 3 have low viscosity, large slice thickness, and high photo-curing ability, and the ceramic materials produced by 3D printing using them have excellent piezoelectric performance (d 33 )

[0052] The slurry of Comparative Example 1 uses only a difunctional aliphatic polyurethane acrylate as the radical photosensitive resin, resulting in a high viscosity of the slurry, a slow curing rate, and low molding strength, resulting in significantly reduced piezoelectric performance of the ceramic material after printing compared to Example 1. In Comparative Example 2, only a trifunctional aliphatic polyurethane acrylate is used as the radical photosensitive resin, resulting in reduced slurry slice thickness and final printing performance compared to Example 1. In Comparative Example 3, only a hexafunctional aliphatic polyurethane acrylate is used as the radical photosensitive resin, resulting in a slurry with a low viscosity that results in high shrinkage after curing, resulting in reduced printing accuracy and significantly reduced piezoelectric performance of the ceramic material after printing compared to Example 1.

[0053] Since no toner was added to the slurry of Comparative Example 4 and the absorbance of the KNN powder was high, which adversely affected the photocuring of the resin, the slice thickness and the piezoelectric performance of the sample were significantly reduced compared to Example 1.

[0054] The slurry of Comparative Example 5 uses adhesion promoter A-171 instead of the adhesion promoter of the present invention. The viscosity of the silane coupling agent A-171 is low, which has a significant adverse effect on curing, resulting in a decrease in the slice thickness (curing effect) of the slurry. Compared with Example 1, the piezoelectric performance of the final print is significantly reduced.

[0055] No anti-settling agent was added to the slurry in Comparative Example 6, and the settling rate of the powder was significantly improved compared to Example 1, exceeding 5% at 30 days, shortening the shelf life of the slurry. In Comparative Example 7, fumed silica was used as the anti-settling agent, which allowed the powder settling rate to be controlled at a low level, but the viscosity of the slurry increased significantly, affecting the photo-curing performance and resulting in a significant decrease in the piezoelectric performance of the final sample.

[0056] In Comparative Example 8, the type of diluent was changed, and HEMA was used as the diluent. Because it has very low viscosity, good flexibility, and is monofunctional, the curing effect was poor. Compared with Example 1, the photo-curing performance of the slurry and the piezoelectric performance of the sample were significantly reduced.

[0057] (Addendum) (Appendix 1) A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, the components of which, by weight, include 50 to 75 parts of potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts of a radical photosensitive resin, 10 to 15 parts of a diluent, 1 to 2 parts of a radical initiator, 1 to 2 parts of a dispersant, 0.5 to 1.5 parts of an anti-settling agent, 0.3 to 1 part of an anti-foaming agent, 0.1 to 1 part of an adhesion promoter, and 0.1 to 1 part of a toner; the radical photosensitive resin contains a difunctional aliphatic polyurethane acrylate, a trifunctional aliphatic polyurethane acrylate, and a hexafunctional aliphatic polyurethane acrylate in a mass ratio of 3 to 5:1 to 3:1; the diluent is selected from at least one of 1,6-hexanediol diacrylate, isobornyl acrylate, and tripropylene glycol diacrylate; the anti-settling agent is at least one of a titanate ester coupling agent, BYK-410; the adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate, hydroxyethyl methacrylic acid phosphate, and CD9051; The toner is a liquid nano white UV pigment. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing.

[0058] (Appendix 2) the radical initiator is selected from at least one of 1-hydroxycyclohexyl phenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone; The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1,

[0059] (Appendix 3) The dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, and triolein. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1,

[0060] (Appendix 4) The antifoaming agent is selected from at least one of a silicone-based agent, a surfactant-based agent, and a paraffin-based agent. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1,

[0061] (Appendix 5) The method for preparing the potassium sodium niobate powder modified with the coupling agent includes: step A) grinding the potassium sodium niobate powder, adding it to a mixed solution of hydrogen peroxide and absolute ethanol, and reacting to obtain potassium sodium niobate hydroxide powder; and step B) reacting the potassium sodium niobate hydroxide powder with a silane coupling agent to obtain the potassium sodium niobate powder modified with the coupling agent. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1,

[0062] (Appendix 6) In step A), the potassium sodium niobate powder is ground and added to a mixed solution of hydrogen peroxide and absolute ethanol, the pH of the system is adjusted to 5.5-6.5, and the mixture is stirred for 8-10 hours to react. The resulting suspension is then centrifuged and washed to obtain potassium sodium niobate hydroxide powder, and the mass ratio of the ground potassium sodium niobate powder to hydrogen peroxide and absolute ethanol is 200-300:30-40:500. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to Appendix 5,

[0063] (Appendix 7) In step A), the particle size of the potassium sodium niobate powder is 400-600 nm, the rotation speed during polishing is 300-500 r / min, and the polishing time is 1-2 h; The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to appendix 5 or 6,

[0064] (Appendix 8) In step B), a silane coupling agent is added to potassium sodium niobate hydroxide powder, ultrasonicated for 30-40 minutes, heated to 95-105°C and kept at the temperature for 1-2 hours, centrifuged, washed, and dried to obtain potassium sodium niobate powder modified with the coupling agent, and the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent is 200-300:2. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to appendix 5 or 6,

[0065] (Appendix 9) (1) preparing a potassium sodium niobate powder modified with a coupling agent; (2) uniformly mixing a radical photosensitive resin, a diluent, and a radical photoinitiator to obtain a photocurable resin mixture; and (3) adding potassium sodium niobate powder modified with a coupling agent to the photocurable resin mixture, adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter and a toner, and then ball milling and vacuum degassing the mixture to obtain the DLP photocurable 3D printing lead-free piezoelectric ceramic slurry. A method for preparing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to any one of appendices 1 to 8, characterized by:

[0066] (Appendix 10) In step (3), the ball milling speed is 4000-5000 r / min, and the ball milling time is 8-10 h. 10. The preparation method according to claim 9,

Claims

1. A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, the ingredients of which, by weight, include 50 to 75 parts of potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts of a radical photosensitive resin, 10 to 15 parts of a diluent, 1 to 2 parts of a radical initiator, 1 to 2 parts of a dispersant, 0.5 to 1.5 parts of an anti-settling agent, 0.3 to 1 part of an anti-foaming agent, 0.1 to 1 part of an adhesion promoter, and 0.1 to 1 part of a toner; the radical photosensitive resin comprises a difunctional aliphatic polyurethane acrylate, a trifunctional aliphatic polyurethane acrylate, and a hexafunctional aliphatic polyurethane acrylate in a mass ratio of 3 to 5:1 to 3:1; the diluent is selected from at least one of 1,6-hexanediol diacrylate, isobornyl acrylate, and tripropylene glycol diacrylate; the anti-settling agent is at least one of a titanate ester coupling agent and BYK-410; the adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate, hydroxyethyl methacrylic acid phosphate, and CD9051; The toner is a liquid nano white UV pigment. A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing.

2. the radical initiator is selected from at least one of 1-hydroxycyclohexyl phenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonic acid ethyl ester, and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone; The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1.

3. The dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, and triolein. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1.

4. The antifoaming agent is selected from at least one of a silicone-based agent, a surfactant-based agent, and a paraffin-based agent. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1.

5. The method for preparing the potassium sodium niobate powder modified with the coupling agent includes: step A) grinding the potassium sodium niobate powder, adding it to a mixed solution of hydrogen peroxide and absolute ethanol, and reacting to obtain potassium sodium niobate hydroxide powder; and step B) reacting the potassium sodium niobate hydroxide powder with a silane coupling agent to obtain the potassium sodium niobate powder modified with the coupling agent. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 1.

6. In step A), the potassium sodium niobate powder is ground, and added to a mixed solution of hydrogen peroxide and absolute ethanol, the pH of the system is adjusted to 5.5-6.5, and the system is stirred for 8-10 hours to react. The resulting suspension is then centrifuged and washed to obtain potassium sodium niobate hydroxide powder, and the mass ratio of the ground potassium sodium niobate powder to hydrogen peroxide and absolute ethanol is 200-300:30-40:

500. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 5.

7. In step A), the particle size of the potassium sodium niobate powder is 400-600 nm, the rotation speed during polishing is 300-500 r / min, and the polishing time is 1-2 h; The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 5 or 6.

8. In step B), a silane coupling agent is added to potassium sodium niobate hydroxide powder, followed by ultrasonic treatment for 30-40 minutes, heating to 95-105°C and keeping the temperature for 1-2 hours, centrifuging, washing, and drying to obtain potassium sodium niobate powder modified with the coupling agent, wherein the mass ratio of the potassium sodium niobate hydroxide powder to the silane coupling agent is 200-300:

2. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to claim 5 or 6.

9. (1) preparing a potassium sodium niobate powder modified with a coupling agent; (2) uniformly mixing a radical photosensitive resin, a diluent and a radical photoinitiator to obtain a photocurable resin mixture; and (3) adding a potassium sodium niobate powder modified with a coupling agent to the photocurable resin mixture, adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter and a toner, and ball milling the mixture and then vacuum degassing the mixture to obtain the lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing. The method for preparing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to any one of claims 1 to 8.

10. In step (3), the ball milling speed is 4000-5000 r / min, and the ball milling time is 8-10 h; 10. The method of claim 9.

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