Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and method for preparing the same

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 particularly to a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and a method for preparing the same.

Background Art

[0002] Lead-based piezoelectric ceramics contain a high concentration of lead, so they are extremely harmful to the environment and the human body and are gradually regulated by laws in various countries. Therefore, environmentally friendly lead-free piezoelectric ceramics, particularly potassium sodium niobate (KNN)-based ceramics, have attracted people's attention because they have a large piezoelectric coefficient, a high Curie temperature, and performance comparable to that of lead zirconate titanate.

[0003] Currently, the manufacture and development of high-performance piezoelectric ceramic components with complex shapes have attracted attention in various fields. However, conventional process methods are difficult to form in one step when manufacturing complex shapes, and subtractive manufacturing with secondary processing is likely to cause defects in piezoelectric ceramics with high strength, high hardness, and brittleness, which affects their use. On the other hand, with the emergence of additive manufacturing technologies such as 3D printing, piezoelectric materials have entered a new development stage. The photocuring 3D printing technology mainly based on DLP (Digital Light Processing) can achieve high-precision, customized, and personalized designs, providing excellent technical means for the finishing of ceramic materials. In addition, when this technology is introduced into the manufacture of KNN piezoelectric ceramics, problems such as dependence on molds, difficulty in manufacturing components with complex shapes and varying functions can be solved.

[0004] Currently, several studies are being conducted on KNN-based ceramic slurries that can be used for 3D printing. For example, Chinese patent document 1 discloses "a method for producing potassium sodium niobate-based lead-free piezoelectric ceramics by stereolithography," and Chinese patent document 2 discloses "potassium sodium niobate-based lead-free piezoelectric ceramic powder, slurry, and process for preparing the same." Both involve preparing a ceramic slurry by mixing potassium sodium niobate ceramic powder with a photoinitiator, photosensitive resin, dispersant, and defoamer, and then performing stereolithography using 3D printing.

[0005] However, conventional ceramic slurries, prepared by mixing potassium sodium niobate ceramic powder with a photoinitiator, photosensitive resin, dispersant, and defoamer, consistently suffer from slow curing speeds and poor adhesion between the slurry and the molding table during printing. Furthermore, the high absorbance of KNN powder negatively affects the photocuring of the resin, resulting in low piezoelectric performance of the 3D printed product. In addition, the ceramic powder in conventional KNN-based 3D printing slurries tends to settle during storage, making storage difficult. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Chinese Patent Application Publication No. 109650887 Specification [Patent Document 1] Chinese Patent Application Publication No. 112608150 Specification [Overview of the project] [Problems that the invention aims to solve]

[0007] This invention provides a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and a method for preparing the same, in order to solve the problems present in conventional KNN-based 3D printing ceramic slurries. This method, by selecting a radical photosensitive resin and combining it with a diluent, enables the slurry to have a high solid content, low viscosity, good fluidity, and a fast curing reaction rate, thus meeting the needs of high-speed printing. By modifying potassium sodium niobate powder using a coupling agent and using it in combination with a dispersant and a settling inhibitor, the settling rate of the powder is significantly reduced, and the shelf life of the slurry is extended. Furthermore, by adding an adhesion promoter and toner, printing accuracy can be improved without affecting the viscosity of the slurry, the density of the sintered product is increased, and the piezoelectric performance is improved. [Means for solving the problem]

[0008] To achieve the above objective, the present invention employs the following technical solutions.

[0009] A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, comprising, by weight, 50 to 75 parts potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts radical photosensitive resin, 10 to 15 parts diluent, 1 to 2 parts radical initiator, 1 to 2 parts dispersant, 0.5 to 1.5 parts anti-settling agent, 0.3 to 1 part defoaming agent, 0.1 to 1 part adhesion promoter, and 0.1 to 1 part toner. The radical photosensitive resin contains a bifunctional 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 aforementioned settling inhibitor is at least one of the titanate ester coupling agent and BYK-410. The adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate, hydroxyethyl methacrylate phosphate, and CD9051. The aforementioned 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 functionality of the resin leads to a faster curing speed and higher molding strength of the slurry, but also results in a rapid increase in shrinkage after curing, i.e., excessive reduction in accuracy and the occurrence of white clipping. To improve the printing performance of the slurry, the present invention selects a specific proportion of difunctional, trifunctional, or hexafunctional fatty polyurethane acrylate as the radical photosensitive resin, and adjusts the viscosity by selecting a low-functionality diluent, which is advantageous for controlling shrinkage during curing. In the system composed of the radical photosensitive resin and diluent of the present invention, by adding and using auxiliary agents such as predetermined types of settling inhibitors, adhesion promoters, and toners, the resulting slurry has a high solid content, low viscosity, good fluidity, a fast curing reaction rate, and a low compressibility after curing, thus meeting the needs of high-speed printing.

[0011] Since the slurry is a suspension, the powder is prone to settling. The present invention provides greater steric hindrance by surface modification treatment of potassium sodium niobate powder using a coupling agent, and by using it in combination with a dispersant and a predetermined settling inhibitor, the settling rate of the powder can be effectively reduced, resulting in a settling rate of less than 5% over 30 days, significantly extending the storage period of the slurry. The present invention avoids the effect of introducing a settling inhibitor on the slurry viscosity by selecting the type of settling inhibitor.

[0012] Because KNN powder is gray and has high absorbency, negatively affecting the photocuring of resins, this invention adjusts the slurry color to be closer to white by adding toner to increase light absorption during 3D printing. At the same time, this invention adds an adhesion promoter to better adhere the components to the aluminum alloy molding table during printing, thereby increasing the success rate of sample printing. Consequently, the slurry in this invention has high printing accuracy, high density after sintering, and good piezoelectric properties. Due to the action of the system formed by each component, this invention makes it possible to obtain a photocurable KNN-based ceramic slurry with high solid load, low shrinkage, low aggregation, low viscosity, slow sedimentation, and stable properties.

[0013] Preferably, the radical initiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonate ethyl ester, and 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, and Triolein.

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

[0016] Preferably, the method for preparing potassium sodium niobate powder modified with the coupling agent includes step A) polishing potassium sodium niobate powder and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol to react and obtain potassium sodium niobate hydroxide powder, and step B) reacting potassium sodium niobate hydroxide powder with a silane coupling agent to obtain potassium sodium niobate powder modified with the coupling agent. In the present invention, by activating the surface of potassium sodium niobate powder with hydrogen peroxide to obtain potassium sodium niobate hydroxide powder, and then reacting it with a silane coupling agent to obtain potassium sodium niobate powder modified with the coupling agent, the specific surface area of ​​potassium sodium niobate powder can be reduced, and together with a dispersant and a sedimentation inhibitor, the sedimentation of potassium sodium niobate powder can be significantly reduced.

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

[0018] Preferably, 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 hours.

[0019] Preferably, in step B), a silane coupling agent is added to potassium sodium niobate powder, sonication is performed for 30-40 minutes, heating is done to 95-105°C and maintained for 1-2 hours, centrifugation is performed, washing is done, and drying is done to obtain potassium sodium niobate powder modified with the coupling agent, the mass ratio of potassium sodium niobate powder to silane coupling agent is 200-300:2.

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

[0021] Preferably, the ball milling speed in step (3) is 4000 - 5000 r / min, and the ball milling time is 8 - 10 h.

Advantages of the Invention

[0022] Therefore, the present invention has the following beneficial effects. (1) The present invention selects bifunctional, trifunctional and hexafunctional aliphatic polyurethane acrylates in a specific ratio as the radical photosensitive resin, and selects a low-functional diluent to adjust the viscosity. The obtained slurry has a high solid content, a low viscosity, good fluidity, a fast curing reaction rate, can meet the needs of high-speed printing, has a high compactness after sintering, good piezoelectric performance, and potential for future applications. (2) The present invention performs surface modification treatment on potassium sodium niobate powder using a coupling agent to provide a greater steric hindrance, and in combination with a dispersant and a predetermined anti-settling agent, can effectively reduce the sedimentation rate of the powder. The sedimentation rate in 30 days is only 5%, and the storage period of the slurry is significantly extended. (3) The present invention adds a toner to adjust the color of the slurry to be closer to white, enhances the light absorption during 3D printing, and avoids the adverse effect of the high absorbance of KNN powder on the photocuring of the resin. (4) The present invention can improve the success rate of sample printing by adding an adhesion promoter to better adhere the components to the aluminum alloy molding table during printing. (5) The lead-free potassium sodium niobate-based ceramic slurry prepared for DLP photocuring 3D printing according to the present invention has high printing accuracy, reaching 50 μm, and the formed structure does not require any subsequent processing after degreasing and sintering. [Modes for carrying out the invention]

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

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

[0025] (General implementation) A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, comprising, by weight, 50 to 75 parts potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts radical photosensitive resin, 10 to 15 parts diluent, 1 to 2 parts radical initiator, 1 to 2 parts dispersant, 0.5 to 1.5 parts anti-settling agent, 0.3 to 1 part defoaming agent, 0.1 to 1 part adhesion promoter, and 0.1 to 1 part toner. The radical photosensitive resin contains a bifunctional 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 aforementioned settling inhibitor is at least one of the titanate ester coupling agent and BYK-410. The adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate (PM-1), hydroxyethyl methacrylate phosphate (PM-2), and CD9051. The aforementioned toner is a liquid nano-white UV pigment.

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

[0027] The radical initiator is selected from at least one of the following: 1-hydroxycyclohexylphenyl ketone (184), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO), 2,4,6-trimethylbenzoylphenylphosphonate ethyl ester (TPO-L), and 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 defoaming agent is selected from at least one of silicone-based, surfactant-based, and paraffin-based agents.

[0030] The method for preparing the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) for preparing potassium sodium niobate powder modified with a coupling agent: Potassium sodium niobate powder with a particle size of 400-600 nm is polished and added to a mixed solution of hydrogen peroxide and anhydrous ethanol. The rotation speed during polishing is 300-500 r / min, the polishing time is 1-2 hours, the mass ratio of the polished potassium sodium niobate powder to the hydrogen peroxide and anhydrous ethanol is 200-300:30-40:500, the pH of the system is adjusted to 5.5-6.5, and the reaction is stirred for 8-10 hours. After that, the resulting suspension is centrifuged and washed to obtain potassium sodium niobate hydroxide powder. Next, a silane coupling agent is added to potassium sodium niobate powder, the mass ratio of potassium sodium niobate powder to silane coupling agent is 200-300:2, the mixture is ultrasonically treated for 30-40 minutes, then heated to 95-105°C and kept warm for 1-2 hours, centrifuged, washed, and dried to obtain potassium sodium niobate powder modified with the coupling agent (1). Step (2) is to uniformly mix a radical photosensitive resin, a diluent, and a radical photoinitiator to obtain a photocurable resin mixture, The process includes (3) adding potassium sodium niobate powder modified with a coupling agent to a photocurable resin mixture, adding a dispersant, anti-settling agent, defoamer, adhesion promoter and toner, ball milling at a speed of 400-450 r / min for 8-10 hours, followed by vacuum degassing 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, comprising, by weight, 50 parts potassium sodium niobate powder modified with a coupling agent, 35 parts radical photosensitive resin, 10 parts diluent HDDA (Shanghai Yinchang New Materials Co., Ltd.), 2 parts radical initiator TPO (Shanghai Yinchang New Materials Co., Ltd.), 2 parts dispersant BYK-111 (Vic Chemie Co., Ltd.), 0.5 parts anti-settling agent BYK-410 (Vic Chemie Co., Ltd.), 0.5 parts silicone defoamer (Dow Corning Co., Ltd.), 0.1 parts adhesion promoter PM-2 (Chengdu Sicheng Optoelectronic Materials Co., Ltd.), and 0.1 parts liquid nano UV pigment (Shenzhen Xinjiayi Technology Co., Ltd., white opaque). The radical photosensitive resin contained bifunctional 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 method for preparing the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) to prepare potassium sodium niobate powder modified with a coupling agent: Potassium sodium niobate powder with an average particle size of 500 nm is polished and added to a mixed solution of hydrogen peroxide and anhydrous ethanol. The rotation speed during polishing is 400 r / min, the polishing time is 1.5 h, the mass ratio of potassium sodium niobate powder to hydrogen peroxide and anhydrous 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 at a rotation speed of 450 r / min for 8 h to allow the reaction to proceed. Step (1) involves centrifugation and washing of the obtained suspension to obtain potassium sodium niobate hydroxide powder, adding silane coupling agent KH550 to the potassium sodium niobate hydroxide powder so that the mass ratio of potassium sodium niobate hydroxide powder to silane coupling agent KH550 is 300:2, sonicating for 30 minutes, heating to 100°C and holding for 1 hour, centrifugation, washing, drying and passing through a 200-mesh sieve to obtain potassium sodium niobate hydroxide powder modified with the coupling agent, and Step (2) involves mixing a radical photosensitive resin, a diluent, and a radical photoinitiator in proportions, stirring at a rotational speed of 400 r / min for 60 min, to obtain a photocurable resin mixture. The process includes (3) adding potassium sodium niobate powder modified with a coupling agent to a photocurable resin mixture, adding a dispersant, anti-settling agent, defoamer, adhesion promoter and toner in proportions, ball milling at a speed of 4500 r / min for 8 hours using a planetary ball mill in B-313, 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, comprising, by weight, 75 parts potassium sodium niobate powder modified with a coupling agent, 36.5 parts radical photosensitive resin, 15 parts diluent TPGDA (Shanghai Yinchang New Materials Co., Ltd.), 2 parts radical initiator TPO (Shanghai Yinchang New Materials Co., Ltd.), 2 parts dispersant BYK-111 (Vic Chemie Inc.), 1.5 parts anti-settling agent BYK-410 (Vic Chemie Inc.), 1 part silicone defoamer (Dow Corning Inc.), 1 part adhesion promoter PM-2 (Chengdu Sicheng Optoelectronic Materials Co., Ltd.), and 1 part liquid nano UV pigment (Shenzhen Xinjiayi Technology, white opaque). The radical photosensitive resin contained a bifunctional aliphatic polyurethane acrylate U600 (Shanghai Guangyi Chemical Co., Ltd.), a trifunctional aliphatic polyurethane acrylate YC3165 (Shanghai Yinchang New Materials Co., Ltd.), and a hexafunctional aliphatic polyurethane acrylate YC3620 (Shanghai Yinchang New Materials Co., Ltd.) in a mass ratio of 3:3:1.

[0034] The method for preparing the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) for preparing potassium sodium niobate powder modified with a coupling agent, wherein potassium sodium niobate powder with an average particle size of 500 nm is polished and added to a mixed solution of hydrogen peroxide and anhydrous ethanol, the rotation speed during polishing is 400 r / min and the polishing time is 2 h, the mass ratio of potassium sodium niobate powder to hydrogen peroxide and anhydrous 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 h to react, Step (1) involves centrifuging and washing the obtained suspension to obtain potassium sodium niobate hydroxide powder, adding the silane coupling agent KH550 to the potassium sodium niobate hydroxide powder so that the mass ratio of potassium sodium niobate hydroxide powder to the silane coupling agent KH550 is 200:2, sonicating for 30 minutes, heating to 100°C and holding for 1 hour, centrifuging, washing, drying, and passing through a 200-mesh sieve to obtain potassium sodium niobate hydroxide powder modified with the coupling agent, and Step (2) involves mixing a radical photosensitive resin, a diluent, and a radical photoinitiator in proportions, stirring at a rotational speed of 400 r / min for 60 min, to obtain a photocurable resin mixture. The process includes (3) adding potassium sodium niobate powder modified with a coupling agent to a photocurable resin mixture, adding a dispersant, anti-settling agent, defoamer, adhesion promoter and toner in proportions, ball milling at a speed of 4500 r / min for 8 hours using a planetary ball mill in B-313, 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 photocuring 3D printing, comprising, by weight, 60 parts potassium sodium niobate powder modified with a coupling agent, 30 parts radical photosensitive resin, 15 parts diluent IBOA (Shanghai Yinchang New Materials Co., Ltd.), 1 part radical initiator TPO (Shanghai Yinchang New Materials Co., Ltd.), 1 part dispersant BYK-111 (Vic Chemie Inc.), 1.5 parts anti-settling agent BYK-410 (Vic Chemie Inc.), 0.5 parts silicone defoamer (Dow Corning Inc.), 0.5 parts adhesion promoter PM-2 (Chengdu Sicheng Optoelectronic Materials Co., Ltd.), and 0.5 parts liquid nano UV pigment (Shenzhen Xinjiayi Technology, white opaque). The radical photosensitive resin contained a bifunctional aliphatic polyurethane acrylate U600 (Shanghai Guangyi Chemical Co., Ltd.), a trifunctional aliphatic polyurethane acrylate YC3165 (Shanghai Yinchang New Materials Co., Ltd.), and a hexafunctional aliphatic polyurethane acrylate YC3620 (Shanghai Yinchang New Materials Co., Ltd.) in a mass ratio of 5:1:1.

[0036] The method for preparing the above-mentioned lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing is as follows: Step (1) for preparing potassium sodium niobate powder modified with a coupling agent, wherein potassium sodium niobate powder with an average particle size of 500 nm is polished and added to a mixed solution of hydrogen peroxide and anhydrous ethanol, the rotation speed during polishing is 400 r / min and the polishing time is 2 h, the mass ratio of potassium sodium niobate powder to hydrogen peroxide and anhydrous ethanol after polishing is 250:30:500, the pH of the system is adjusted to 6.0, and the reaction is carried out by stirring at a rotation speed of 450 r / min at room temperature for 8 h, Step (1) involves centrifuging and washing the obtained suspension to obtain potassium sodium niobate hydroxide powder, adding the silane coupling agent KH550 to the potassium sodium niobate hydroxide powder so that the mass ratio of potassium sodium niobate hydroxide powder to the silane coupling agent KH550 is 250:2, sonicating for 30 minutes, heating to 100°C and holding for 1 hour, centrifuging, washing, drying and passing through a 200-mesh sieve to obtain potassium sodium niobate hydroxide powder modified with the coupling agent, and Step (2) involves mixing a radical photosensitive resin, a diluent, and a radical photoinitiator in proportions, stirring at a rotational speed of 400 r / min for 60 min, to obtain a photocurable resin mixture. The process includes (3) adding potassium sodium niobate powder modified with a coupling agent to a photocurable resin mixture, adding a dispersant, anti-settling agent, defoamer, adhesion promoter and toner in proportions, ball milling at a speed of 4500 r / min for 8 hours using a planetary ball mill in B-313, 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 all radical photosensitive resins used were bifunctional aliphatic polyurethane acrylate U600, but otherwise it was the same as Example 1.

[0038] (Comparative Example 2) Comparative Example 2 differed from Example 1 in that all radical photosensitive resins used were trifunctional aliphatic polyurethane acrylate YC3165, but otherwise it was the same as Example 1.

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

[0040] (Comparative Example 4) Comparative Example 4 differed from Example 1 in that toner was not added to the slurry, but otherwise it was the same as Example 1.

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

[0042] (Comparative Example 6) Comparative Example 6 differed from Example 1 in that no settling inhibitor was added to the slurry, but otherwise it was the same as Example 1.

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

[0044] (Comparative Example 8) Comparative Example 8 differed from Example 1 in that it used hydroxyethyl methacrylate (HEMA) as a diluent, but was otherwise the same as Example 1.

[0045] The performance of the slurries prepared in the above examples and comparative examples, and the performance of the 3D printed 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] Method for testing sedimentation velocity: 50g of slurry was sealed and stored. Every 120 hours, the slurry was poured into a new beaker, and the mass of the ceramic particles and slurry deposited at the bottom of the original beaker was measured to obtain the sedimentation velocity.

[0048] Test method for slice thickness and piezoelectric performance of ceramic material: A slurry was 3D printed using a DLP apparatus based on the photocuring principle, and the maximum exposure thickness (slice thickness) of each layer was measured. Then, a final sample was obtained by printing, and the sample was placed in a box-type furnace for binder removal. It was gradually heated to 200°C and 400°C at 0.15°C / min, with holding time for 3 hours each. Next, it was gradually heated to 550°C and 600°C at 0.25°C / min, with holding time for 2.5 hours each, and then allowed to cool naturally. After that, it was heated to 1050°C at 5°C / min in an air atmosphere, with holding time for 4 hours, and then allowed to cool naturally to obtain a sintered KNN ceramic sample. Silver paste was applied to both the front and back surfaces of the sintered KNN ceramic sample, dried, and then fired at 600°C for 30 minutes. Silicone oil was heated to 120°C, and polarization was performed with a DC current of 3kV / mm for 20 minutes. Its piezoelectric performance was measured using a quasi-static analyzer. 33 I tested it.

[0049] [Table 1]

[0050] [Table 2]

[0051] As can be seen from Tables 1 and 2, the slurries prepared using the formulation and method of the present invention in Examples 1 to 3 had low viscosity, large slice thickness, and high photocuring ability, and the ceramic materials manufactured using them by 3D printing had excellent piezoelectric properties (d 33 ) has.

[0052] In Comparative Example 1, the slurry used only a bifunctional aliphatic polyurethane acrylate as the radical photosensitive resin, resulting in high slurry viscosity, slow curing speed, and low molding strength. Compared to Example 1, the piezoelectric performance of the ceramic material after printing was significantly reduced. In Comparative Example 2, only a trifunctional aliphatic polyurethane acrylate was used as the radical photosensitive resin, resulting in reduced slurry slice thickness and lower final printing performance compared to Example 1. In Comparative Example 3, only a hexafunctional aliphatic polyurethane acrylate was used as the radical photosensitive resin, resulting in excessively low slurry viscosity and high shrinkage after curing. Consequently, printing accuracy was low, and the piezoelectric performance of the ceramic material after printing was significantly reduced compared to Example 1.

[0053] In Comparative Example 4, toner was not added to the slurry, and the absorbance of the KNN powder was high, which adversely affected the photocuring of the resin. As a result, the slice thickness and piezoelectric performance of the sample were significantly reduced compared to Example 1.

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

[0055] In Comparative Example 6, no settling inhibitor was added to the slurry, and the powder settling rate was significantly improved compared to Example 1, with the settling rate at 30d exceeding 5%, resulting in a shorter storage period for the slurry. In Comparative Example 7, fumed silica was used as the settling inhibitor, which allowed for control of the powder settling rate to a low level, but the viscosity of the slurry increased significantly, affecting the photocuring performance, and the piezoelectric performance of the final produced sample was significantly reduced.

[0056] In Comparative Example 8, the type of diluent was changed, and HEMA was used as the diluent. Because its viscosity is very low, its flexibility is good, and it is monofunctional, the curing effect is not good, and the photocuring performance of the slurry and the piezoelectric performance of the sample are significantly lower compared to Example 1.

[0057] (Note) (Note 1) A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, comprising, by weight, 50 to 75 parts potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts radical photosensitive resin, 10 to 15 parts diluent, 1 to 2 parts radical initiator, 1 to 2 parts dispersant, 0.5 to 1.5 parts anti-settling agent, 0.3 to 1 part defoaming agent, 0.1 to 1 part adhesion promoter, and 0.1 to 1 part toner. The radical photosensitive resin contains a bifunctional 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 aforementioned settling inhibitor is at least one of the titanate ester coupling agent and BYK-410. The adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate, hydroxyethyl methacrylate phosphate, and CD9051. The aforementioned toner is a liquid nano-white UV pigment. A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, characterized by the following features.

[0058] (Note 2) The radical initiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonate ethyl ester, and 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 1, characterized by the features described herein.

[0059] (Note 3) The dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, and Triolein. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 1, characterized by the features described herein.

[0060] (Note 4) The aforementioned defoaming agent is selected from at least one of silicone-based, surfactant-based, and paraffin-based agents. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 1, characterized by the features described herein.

[0061] (Note 5) A method for preparing potassium sodium niobate powder modified with the coupling agent includes step A) polishing potassium sodium niobate powder and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol to react and obtain potassium sodium niobate hydroxide powder, and step B) reacting potassium sodium niobate hydroxide powder with a silane coupling agent to obtain potassium sodium niobate powder modified with the coupling agent. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 1, characterized by the features described herein.

[0062] (Note 6) In step A), potassium sodium niobate powder is polished and added to a mixed solution of hydrogen peroxide and anhydrous ethanol. The pH of the system is adjusted to 5.5-6.5, and the reaction is stirred for 8-10 hours. After that, the resulting suspension is centrifuged and washed to obtain potassium sodium niobate hydroxide powder. The mass ratio of the polished potassium sodium niobate powder to the hydrogen peroxide and anhydrous ethanol is 200-300:30-40:500. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 5, characterized by the features described herein.

[0063] (Note 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 hours. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 5 or 6, characterized by the above.

[0064] (Note 8) In step B), a silane coupling agent is added to potassium sodium niobate powder, ultrasonic treatment is performed for 30-40 minutes, heating is carried out at 95-105°C for 1-2 hours, centrifugation is performed, washing is done, and drying is done to obtain potassium sodium niobate powder modified with the coupling agent, the mass ratio of potassium sodium niobate powder to silane coupling agent is 200-300:2. Lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in Appendix 5 or 6, characterized by the above.

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

[0066] (Note 10) The ball milling speed in step (3) is 4000-5000 r / min, and the ball milling time is 8-10 h. The preparation method described in Appendix 9, characterized by the features described herein.

Claims

1. A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, comprising, by weight, 50 to 75 parts potassium sodium niobate powder modified with a coupling agent, 20 to 36.5 parts radical photosensitive resin, 10 to 15 parts diluent, 1 to 2 parts radical initiator, 1 to 2 parts dispersant, 0.5 to 1.5 parts settling inhibitor, 0.3 to 1 part defoaming agent, 0.1 to 1 part adhesion promoter, and 0.1 to 1 part toner. The radical photosensitive resin contains a bifunctional 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 aforementioned settling inhibitor is a titanate ester coupling agent. The adhesion promoter is at least one of 2-methacryloyloxyethyl acid phosphate and hydroxyethyl methacrylate phosphate. The aforementioned toner is a liquid pigment, a nanopigment, and a white UV pigment. A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, characterized by the following features.

2. The radical initiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylphenylphosphonate 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 as described in claim 1.

3. The aforementioned dispersant is triolein. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in claim 1.

4. The aforementioned defoaming agent is selected from at least one of silicone-based, surfactant-based, and paraffin-based agents. The lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing as described in claim 1.

5. A method for manufacturing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to Claim 1, A method for preparing potassium sodium niobate powder modified with the coupling agent includes step A) polishing potassium sodium niobate powder and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol to react and obtain potassium sodium niobate hydroxide powder, and step B) reacting potassium sodium niobate hydroxide powder with a silane coupling agent to obtain potassium sodium niobate powder modified with the coupling agent. A method for manufacturing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, characterized by the features described above.

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

500. A method for producing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, as described in claim 5.

7. 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. A method for producing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, as described in 5 or 6.

8. In step B), a silane coupling agent is added to potassium sodium niobate powder, ultrasonic treatment is performed for 30-40 min, heating is carried out to 95-105°C for 1-2 hours, centrifugal separation is performed, washing is done, and drying is done to obtain potassium sodium niobate powder modified with the coupling agent, the mass ratio of potassium sodium niobate powder to silane coupling agent is 200-300:

2. A method for producing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, as described in 5 or 6.

9. A method for preparing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing according to Claim 1, Step (1) prepares potassium sodium niobate powder modified with a coupling agent, Step (2) is to uniformly mix a radical photosensitive resin, a diluent, and a radical photoinitiator to obtain a photocurable resin mixture, The process includes (3) adding potassium sodium niobate powder modified with a coupling agent to a photocurable resin mixture, adding a dispersant, an anti-settling agent, an anti-foaming agent, an adhesion promoter, and a toner, ball milling, and then vacuum degassing to obtain the DLP photocurable lead-free piezoelectric ceramic slurry for 3D printing. A method for preparing a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, characterized by the following:

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

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