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

Abstract

The present invention relates to the field of 3D printing materials. Disclosed are a lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing and a preparation method therefor. The components of the lead-free piezoelectric ceramic slurry comprise a coupling-agent-modified potassium sodium niobate powder, a free-radical-type photosensitive resin, a diluent, a free-radical-type initiator, a dispersing agent, an anti-settling agent, a defoaming agent, an adhesion promoter and a toner, wherein the free-radical-type photosensitive resin comprises bifunctional, trifunctional and hexafunctional aliphatic polyurethane acrylates. By selecting a specific free-radical-type photosensitive resin and combining same with a diluent, the slurry has a high content of solids with regard to volume, low viscosity, good fluidity and a fast curing reaction speed, and meets a requirement for rapid printing; a coupling agent is used for modifying a potassium sodium niobate powder, the modified powder is coordinated with a dispersing agent and an anti-settling agent for use, and therefore the settling rate of the powder is significantly reduced, thereby prolonging the shelf life of the slurry; moreover, an adhesion promoter and a toner are also added, and therefore the printing precision is improved, and a sintered product has a high density and good piezoelectric properties.

Description

A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing and its preparation method 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 light-curing 3D printing and a preparation method thereof. Background Art

[0002] Lead-based piezoelectric ceramics, due to their high lead concentrations, are extremely harmful to the environment and human health, and have been gradually restricted by legislation in various countries. Consequently, environmentally friendly lead-free piezoelectric ceramics, particularly potassium sodium niobate (KNN)-based ceramics, are gaining popularity due to their larger piezoelectric coefficients, higher Curie temperatures, and performance comparable to lead zirconate titanate.

[0003] Currently, the manufacturing and development of high-performance piezoelectric ceramic parts with complex shapes has become a focus of attention in various fields. However, traditional process methods are difficult to form in one go when manufacturing complex shapes, and subtractive manufacturing through secondary processing can easily cause defects in piezoelectric ceramics with high strength, high hardness, and brittleness, thus affecting their use. The rise of additive manufacturing technology such as 3D printing has brought piezoelectric materials into a new stage of development. Among them, light-curing 3D printing technology based on DLP (Digital Light Processing) can achieve high-precision, customized, and personalized designs, providing a better technical means for the fine processing of ceramic materials. Introducing this technology into KNN piezoelectric ceramic manufacturing will solve problems such as mold dependence, the difficulty in manufacturing parts with complex shapes and multiple functional changes.

[0004] At present, there have been some studies on KNN-based ceramic slurries that can be used for 3D printing. For example, the Chinese patent document with publication number CN109650887A discloses "A method for preparing lead-free potassium sodium niobate-based piezoelectric ceramics for photocuring molding"; the Chinese patent document with publication number CN112608150A discloses "A potassium sodium niobate-based lead-free piezoelectric ceramic powder and slurry and its preparation process"; both of them are to mix potassium sodium niobate ceramic powder with a photoinitiator, a photosensitive resin, a dispersant, and a defoaming agent to form a ceramic slurry, and then use 3D printing photocuring molding.

[0005] However, the ceramic slurry made by mixing potassium sodium niobate ceramic powder with a photoinitiator, photosensitive resin, dispersant, and defoaming agent in the existing technology generally has problems such as slow curing speed and poor adhesion between the slurry and the forming table during printing. In addition, the KNN powder has a high absorbance, which will adversely affect the photocuring of the resin, resulting in poor piezoelectric performance of the 3D printed product. In addition, the ceramic powder in the KNN-based 3D printing slurry in the existing technology is prone to sedimentation during storage, which is not conducive to preservation.

[0006] Summary of the Invention

[0007] The present invention aims to overcome the above-mentioned problems of KNN-based 3D printing ceramic slurry in the prior art, and provides a lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing and a preparation method thereof. A free radical photosensitive resin and a diluent combination are selected to make the slurry have high solid volume, low viscosity, good fluidity, and fast curing reaction speed, thereby meeting the requirements of fast printing; a coupling agent is used to modify the potassium sodium niobate powder, and a dispersant and an anti-settling agent are used in combination to significantly reduce the powder sedimentation rate and improve the shelf life of the slurry; an adhesion promoter and a toner are added at the same time to improve the printing accuracy without affecting the viscosity of the slurry. After sintering, the product has high density and good piezoelectric properties.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, comprising, by weight, 50-75 parts of coupling agent-modified potassium sodium niobate powder, 20-36.5 parts of a free radical photosensitive resin, 10-15 parts of a diluent, 1-2 parts of a free radical initiator, 1-2 parts of a dispersant, 0.5-1.5 parts of an anti-settling agent, 0.3-1 part of a defoaming agent, 0.1-1 part of an adhesion promoter, and 0.1-1 part of a toner; the free 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 3-5:1 to 3:1;

[0010] The diluent is selected from at least one of 1,6-hexanediol diacrylate, isobornyl acrylate, and tripropylene glycol diacrylate;

[0011] The anti-settling agent is at least one of a titanate coupling agent and BYK-410;

[0012] The adhesion promoter is at least one of 2-methyl-2-acrylic acid-2-hydroxyethyl ester phosphate, hydroxyethyl methacrylate phosphate, and CD9051;

[0013] The toner is a liquid nano white UV pigment.

[0014] The type and functionality of the free radical photosensitive resin and diluent have a significant impact on the 3D printing performance of the slurry. The higher the functionality of the resin, the faster the curing speed of the slurry and the further increase in the molding strength. However, the consequence is a rapid increase in the shrinkage rate after curing, that is, an excessive decrease in precision and the occurrence of overexposure. In order to improve the printing performance of the slurry, the present invention selects a specific proportion of difunctional, trifunctional, and hexafunctional fatty polyurethane acrylates as the free radical photosensitive resin, and uses a low-functionality diluent to adjust its viscosity. The low-functionality diluent is beneficial to shrinkage control during the curing process. In the system composed of the free radical photosensitive resin and the diluent in the present invention, a certain type of anti-settling agent, adhesion promoter, toner and other additives are added for use. The resulting slurry has high volume solids, low viscosity, good fluidity, fast curing reaction speed, and low shrinkage rate after curing, which meets the needs of fast printing.

[0015] Because slurries are suspensions, powders are prone to sedimentation. This invention uses a coupling agent to surface-modify potassium sodium niobate powder, imparting significant steric hindrance. Combined with a dispersant and a specific anti-settling agent, this effectively reduces the powder's sedimentation rate, achieving a 30-day sedimentation rate of less than 5%, significantly extending the slurry's shelf life. The invention also minimizes the effects of the anti-settling agent on slurry viscosity by carefully selecting the type of anti-settling agent.

[0016] Because KNN powder is gray and has high light absorbance, which can adversely affect the photocuring of the resin, the present invention incorporates a colorant to adjust the slurry's color to near white, enhancing light absorption during 3D printing. Furthermore, the present invention incorporates an adhesion promoter to improve adhesion of parts to the aluminum alloy forming table during printing, increasing the success rate of sample printing. As a result, the slurry of the present invention achieves high printing precision, high density after sintering, and excellent piezoelectric properties. The combined action of these components yields a stable, photocurable KNN-based ceramic slurry with high solid loading, low shrinkage, minimal agglomeration, low viscosity, and slow sedimentation.

[0017] Preferably, the free radical initiator is selected from at least one of 1-hydroxycyclohexyl phenyl ketone, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

[0018] Preferably, the dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, and triolein.

[0019] Preferably, the defoaming agent is selected from at least one of silicones, surfactants and paraffins.

[0020] Preferably, the coupling agent-modified potassium sodium niobate powder is prepared by: A) sand-grinding potassium sodium niobate powder and then adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol to react to obtain hydroxylated potassium sodium niobate powder; and B) reacting the hydroxylated potassium sodium niobate powder with a silane coupling agent to obtain the coupling agent-modified potassium sodium niobate powder. The present invention first activates the surface of the potassium sodium niobate powder with hydrogen peroxide to obtain the hydroxylated potassium sodium niobate powder, which is then reacted with the silane coupling agent to obtain the coupling agent-modified potassium sodium niobate powder. This reduces the specific surface area of ​​the potassium sodium niobate powder, allowing it to interact with a dispersant and an anti-settling agent to significantly reduce sedimentation of the potassium sodium niobate powder.

[0021] Preferably, in step A), the potassium sodium niobate powder is sand-ground and then 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 mixture is stirred and reacted for 8-10 hours. The resulting suspension is centrifuged and washed to obtain hydroxylated potassium sodium niobate powder; the mass ratio of the sand-ground potassium sodium niobate powder to hydrogen peroxide and anhydrous ethanol is 200-300:30-40:500.

[0022] Preferably, the particle size of the potassium sodium niobate powder in step A) is 400-600 nm; the rotation speed during sand milling is 300-500 r / min, and the sand milling time is 1-2 h.

[0023] Preferably, in step B), a silane coupling agent is added to the hydroxylated potassium sodium niobate powder, ultrasonically treated for 30 to 40 minutes, then heated to 95 to 105° C. for 1 to 2 hours, centrifuged, washed, and dried to obtain the coupling agent-modified potassium sodium niobate powder; the mass ratio of the hydroxylated potassium sodium niobate powder to the silane coupling agent is 200 to 300:2.

[0024] The present invention also provides a method for preparing the lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, comprising the following steps:

[0025] (1) preparing coupling agent-modified potassium sodium niobate powder;

[0026] (2) uniformly mixing a free radical photosensitive resin, a diluent, and a free radical photoinitiator to obtain a photocurable resin mixture;

[0027] (3) adding coupling agent-modified potassium sodium niobate powder to a photocurable resin mixture, and then adding a dispersant, an anti-settling agent, a defoaming agent, an adhesion promoter, and a toner, ball milling, and vacuum defoaming to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0028] Preferably, the ball milling speed in step (3) is 4000-5000 r / min, and the ball milling time is 8-10 h.

[0029] Therefore, the present invention has the following beneficial effects:

[0030] (1) The present invention selects a specific ratio of difunctional, trifunctional, and hexafunctional fatty polyurethane acrylates as free radical photosensitive resins, and uses a low-functionality diluent to adjust the viscosity thereof. The resulting slurry has high volume solids, low viscosity, good fluidity, and a fast curing reaction speed, which meets the requirements of fast printing. After sintering, it has high density and good piezoelectric properties, and has application prospects.

[0031] (2) The present invention uses a coupling agent to modify the surface of potassium sodium niobate powder to give it greater steric hindrance. In combination with a dispersant and a certain anti-settling agent, the sedimentation rate of the powder can be effectively reduced. The 30-day sedimentation rate is only 5%, which greatly extends the shelf life of the slurry.

[0032] (3) The present invention adds a toner to adjust the color of the slurry to near white, thereby increasing the light absorption during 3D printing and avoiding the adverse effect of the large absorbance of KNN powder on the light curing of the resin;

[0033] (4) The present invention adds an adhesion promoter, which can make the parts adhere better to the forming table of the aluminum alloy material during the printing process, thereby increasing the success rate of sample printing;

[0034] (5) The lead-free potassium sodium niobate-based ceramic slurry for DLP light-curing 3D printing prepared by the present invention has high printing accuracy, which can reach 50 μm, and the molded structure does not require subsequent processing after degreasing and sintering. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific embodiments.

[0036] In the present invention, unless otherwise specified, all equipment and raw materials can be purchased from the market or are commonly used in the industry. The methods in the following embodiments, unless otherwise specified, are all conventional methods in the art.

[0037] Overall embodiment

[0038] A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, comprising, by weight, 50-75 parts of coupling agent-modified potassium sodium niobate powder, 20-36.5 parts of a free radical photosensitive resin, 10-15 parts of a diluent, 1-2 parts of a free radical initiator, 1-2 parts of a dispersant, 0.5-1.5 parts of an anti-settling agent, 0.3-1 part of a defoaming agent, 0.1-1 part of an adhesion promoter, and 0.1-1 part of a toner; the free 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 3-5:1 to 3:1;

[0039] The anti-settling agent is at least one of a titanate coupling agent and BYK-410;

[0040] The adhesion promoter is at least one of 2-methyl-2-acrylate-2-hydroxyethyl phosphate (PM-1), hydroxyethyl methacrylate phosphate (PM-2), and CD9051;

[0041] The toner is a liquid nano white UV pigment;

[0042] The diluent is selected from at least one of hexylene glycol diacrylate (HDDA), hydroxyethyl acrylate (HEA), isobornyl acrylate (IBOA), tripropylene glycol diacrylate (TPGDA), dipropylene glycol diacrylate (DPGDA), pentaerythritol tetraacrylate (PETEA), and trimethylolpropane triacrylate (TMPTA);

[0043] The free radical initiator is selected from at least one of 1-hydroxycyclohexylphenyl ketone (184), phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (819), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoylphenylphosphonate (TPO-L), and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone (659);

[0044] The dispersant is selected from at least one of BYK-111, BYK-142, Triton X-100, PM1590, and triolein;

[0045] The defoaming agent is selected from at least one of silicones, surfactants, and paraffins;

[0046] The preparation method of the lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing comprises the following steps:

[0047] (1) Preparing coupling agent modified potassium sodium niobate powder: sand-milling potassium sodium niobate powder with a particle size of 400-600 nm and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol, the speed of sand-milling is 300-500 r / min, the sand-milling time is 1-2 h, the mass ratio of the sand-milled potassium sodium niobate powder to hydrogen peroxide and anhydrous ethanol is 200-300:30-40:500, adjusting the pH of the system to 5.5-6.5, stirring and reacting for 8-10 h, centrifuging and washing the obtained suspension to obtain hydroxylated potassium sodium niobate powder; adding a silane coupling agent to the hydroxylated potassium sodium niobate powder, the mass ratio of the hydroxylated potassium sodium niobate powder to the silane coupling agent is 200-300:2, ultrasonically treating for 30-40 min, then heating to 95-105° C. and keeping warm for 1-2 h, centrifuging, washing, and drying to obtain the coupling agent modified potassium sodium niobate powder;

[0048] (2) uniformly mixing a free radical photosensitive resin, a diluent, and a free radical photoinitiator to obtain a photocurable resin mixture;

[0049] (3) Adding coupling agent-modified potassium sodium niobate powder to a photocurable resin mixture, and then adding a dispersant, an anti-settling agent, a defoaming agent, an adhesion promoter and a toner, ball milling at a speed of 400 to 450 r / min for 8 to 10 hours, and then vacuum defoaming to obtain the lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing.

[0050] Example 1:

[0051] A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, comprising, by weight, 50 parts of coupling agent-modified potassium sodium niobate powder, 35 parts of free radical photosensitive resin, 10 parts of diluent HDDA (Yinchang New Materials), 2 parts of free radical initiator TPO (Yinchang New Materials), 2 parts of dispersant BYK-111 (BYK Chemical), 0.5 parts of anti-settling agent BYK-410 (BYK Chemical), 0.5 parts of silicone defoamer (Dow Corning), 0.1 parts of adhesion promoter PM-2 (Sicheng Optoelectronics), and 0.1 parts of liquid nano-UV pigment (Shenzhen Xinjiayi Technology, white opaque).

[0052] The free radical photosensitive resin includes difunctional aliphatic polyurethane acrylate U600 (Guangyi Chemical), trifunctional aliphatic polyurethane acrylate YC3165 (Yinchang New Materials), and hexafunctional aliphatic polyurethane acrylate YC3620 (Yinchang New Materials) in a mass ratio of 4:2:1;

[0053] The preparation method of the lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing comprises the following steps:

[0054] (1) Preparing coupling agent modified potassium sodium niobate powder: sand-milling potassium sodium niobate powder with an average particle size of 500 nm and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol, the speed of sand-milling is 400 r / min, the sand-milling time is 1.5 h, the mass ratio of the sand-milled potassium sodium niobate powder to hydrogen peroxide and anhydrous ethanol is 300:30:500, adjusting the pH of the system to 6.0, stirring at 450 r / min at room temperature for 8 h, centrifuging and washing the obtained suspension to obtain hydroxylated potassium sodium niobate powder; adding silane coupling agent KH550 to the hydroxylated potassium sodium niobate powder, the mass ratio of the hydroxylated potassium sodium niobate powder to the silane coupling agent KH550 is 300:2, ultrasonically treating for 30 min, then heating to 100° C. and keeping warm for 1 h, centrifuging, washing, drying, and then passing through a 200-mesh sieve to obtain the coupling agent modified potassium sodium niobate powder;

[0055] (2) mixing a free radical photosensitive resin, a diluent, and a free radical photoinitiator in proportion, and stirring at a speed of 400 r / min for 60 min to obtain a light-curable resin mixture;

[0056] (3) The coupling agent-modified potassium sodium niobate powder is added to the photocurable resin mixture, and then a dispersant, an anti-settling agent, a defoaming agent, an adhesion promoter and a toner are added in proportion. After ball milling at a speed of 4500 r / min for 8 hours in a B-313 planetary ball mill, vacuum defoaming is performed to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0057] Example 2:

[0058] A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, comprising, by weight, 75 parts of coupling agent-modified potassium sodium niobate powder, 36.5 parts of free radical photosensitive resin, 15 parts of diluent TPGDA (Yinchang New Materials), 2 parts of free radical initiator TPO (Yinchang New Materials), 2 parts of dispersant BYK-111 (BYK Chemical), 1.5 parts of anti-settling agent BYK-410 (BYK Chemical), 1 part of silicone defoamer (Dow Corning), 1 part of adhesion promoter PM-2 (Sicheng Optoelectronics), and 1 part of liquid nano-UV pigment (Shenzhen Xinjiayi Technology, white opaque).

[0059] The free radical photosensitive resin includes difunctional aliphatic polyurethane acrylate U600 (Guangyi Chemical), trifunctional aliphatic polyurethane acrylate YC3165 (Yinchang New Materials), and hexafunctional aliphatic polyurethane acrylate YC3620 (Yinchang New Materials) in a mass ratio of 3:3:1;

[0060] The preparation method of the lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing comprises the following steps:

[0061] (1) Preparing coupling agent modified potassium sodium niobate powder: sand-milling potassium sodium niobate powder with an average particle size of 500 nm and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol, the speed of sand-milling is 400 r / min, the sand-milling time is 2 h, the mass ratio of the sand-milled potassium sodium niobate powder to hydrogen peroxide and anhydrous ethanol is 200:30:500, adjusting the pH of the system to 6.0, stirring at 450 r / min at room temperature for 8 h, centrifuging and washing the obtained suspension to obtain hydroxylated potassium sodium niobate powder; adding silane coupling agent KH550 to the hydroxylated potassium sodium niobate powder, the mass ratio of the hydroxylated potassium sodium niobate powder to the silane coupling agent KH550 is 200:2, ultrasonically treating for 30 min, then heating to 100° C. and keeping warm for 1 h, centrifuging, washing, drying, and then passing through a 200-mesh sieve to obtain the coupling agent modified potassium sodium niobate powder;

[0062] (2) mixing a free radical photosensitive resin, a diluent, and a free radical photoinitiator in proportion, and stirring at a speed of 400 r / min for 60 min to obtain a light-curable resin mixture;

[0063] (3) The coupling agent-modified potassium sodium niobate powder is added to the photocurable resin mixture, and then a dispersant, an anti-settling agent, a defoaming agent, an adhesion promoter and a toner are added in proportion. After ball milling at a speed of 4500 r / min for 8 hours in a B-313 planetary ball mill, vacuum defoaming is performed to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0064] Example 3:

[0065] A lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing, comprising, by weight, 60 parts of coupling agent-modified potassium sodium niobate powder, 30 parts of free radical photosensitive resin, 15 parts of diluent IBOA (Yinchang New Materials), 1 part of free radical initiator TPO (Yinchang New Materials), 1 part of dispersant BYK-111 (BYK Chemical), 1.5 parts of anti-settling agent BYK-410 (BYK Chemical), 0.5 part of silicone defoamer (Dow Corning), 0.5 part of adhesion promoter PM-2 (Sicheng Optoelectronics), and 0.5 part of liquid nano-UV pigment (Shenzhen Xinjiayi Technology, white opaque).

[0066] The free radical photosensitive resin includes difunctional aliphatic polyurethane acrylate U600 (Guangyi Chemical), trifunctional aliphatic polyurethane acrylate YC3165 (Yinchang New Materials) and hexafunctional aliphatic polyurethane acrylate YC3620 (Yinchang New Materials) in a mass ratio of 5:1:1;

[0067] The preparation method of the lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing comprises the following steps:

[0068] (1) Preparing coupling agent modified potassium sodium niobate powder: sand-milling potassium sodium niobate powder with an average particle size of 500 nm and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol, the speed of sand-milling is 400 r / min, the sand-milling time is 2 h, the mass ratio of the sand-milled potassium sodium niobate powder to hydrogen peroxide and anhydrous ethanol is 250:30:500, adjusting the pH of the system to 6.0, stirring at 450 r / min at room temperature for 8 h, centrifuging and washing the obtained suspension to obtain hydroxylated potassium sodium niobate powder; adding silane coupling agent KH550 to the hydroxylated potassium sodium niobate powder, the mass ratio of the hydroxylated potassium sodium niobate powder to the silane coupling agent KH550 is 250:2, ultrasonically treating for 30 min, then heating to 100° C. and keeping warm for 1 h, centrifuging, washing, drying, and then passing through a 200-mesh sieve to obtain the coupling agent modified potassium sodium niobate powder;

[0069] (2) mixing a free radical photosensitive resin, a diluent, and a free radical photoinitiator in proportion, and stirring at a speed of 400 r / min for 60 min to obtain a light-curable resin mixture;

[0070] (3) The coupling agent-modified potassium sodium niobate powder is added to the photocurable resin mixture, and then a dispersant, an anti-settling agent, a defoaming agent, an adhesion promoter and a toner are added in proportion. After ball milling at a speed of 4500 r / min for 8 hours in a B-313 planetary ball mill, vacuum defoaming is performed to obtain the lead-free piezoelectric ceramic slurry for DLP photocurable 3D printing.

[0071] Comparative Example 1:

[0072] The difference between Comparative Example 1 and Example 1 is that the free radical photosensitive resin is all difunctional aliphatic polyurethane acrylate U600, and the rest is the same as in Example 1.

[0073] Comparative Example 2:

[0074] The difference between Comparative Example 2 and Example 1 is that the free radical photosensitive resin is all trifunctional aliphatic polyurethane acrylate YC3165, and the rest is the same as in Example 1.

[0075] Comparative Example 3:

[0076] The difference between Comparative Example 3 and Example 1 is that the free radical photosensitive resin is all hexafunctional aliphatic polyurethane acrylate YC3620, and the rest is the same as in Example 1.

[0077] Comparative Example 4:

[0078] The difference between Comparative Example 4 and Example 1 is that no toner is added to the slurry, and the rest is the same as in Example 1.

[0079] Comparative Example 5:

[0080] The difference between Comparative Example 5 and Example 1 is that the adhesion promoter uses A-171 (Shengshi New Materials), and the rest is the same as in Example 1.

[0081] Comparative Example 6:

[0082] The difference between Comparative Example 6 and Example 1 is that no anti-settling agent is added to the slurry, and the rest is the same as in Example 1.

[0083] Comparative Example 7:

[0084] The difference between Comparative Example 7 and Example 1 is that fumed silica is used as the anti-settling agent, and the rest is the same as in Example 1.

[0085] Comparative Example 8:

[0086] The difference between Comparative Example 8 and Example 1 is that hydroxyethyl methacrylate (HEMA) is used as the diluent, and the rest is the same as in Example 1.

[0087] The properties of the slurries prepared in the above examples and comparative examples and the properties of the 3D printed ceramic materials thereof were tested, and the results are shown in Tables 1 and 2;

[0088] Among them, the slurry viscosity was measured using NDJ-8S viscometer;

[0089] The sedimentation rate test method is as follows: take 50g of slurry, seal it and pour it into a new beaker every 120 hours. Measure the mass of ceramic particles and slurry deposited at the bottom of the original beaker to obtain the sedimentation rate.

[0090] The test method for slice thickness and piezoelectric properties of ceramic materials is as follows: the slurry is used for 3D printing with a DLP device based on the principle of photocuring, the maximum exposure thickness of each layer (slice thickness) is measured first, and then the final sample is printed based on this. The sample is then placed in a box furnace for debinding, and the temperature is raised to 200℃ and 400℃ at a rate of 0.15℃ / min, and kept warm for 3 hours respectively. Then, the temperature is raised to 550℃ and 600℃ at a rate of 0.25℃ / min, and kept warm for 2.5 hours respectively, and then cooled naturally; then, the temperature is raised to 1050℃ at a rate of 5℃ / min in an air atmosphere, kept warm for 4 hours, and then cooled naturally to obtain a sintered KNN ceramic sample; silver paste is applied to both sides of the sintered KNN ceramic sample, and after drying, it is calcined at 600℃ for 30 minutes; silicone oil is heated at 120℃ and polarized with 3kV / mm DC for 20 minutes; its piezoelectric properties are tested by measuring the quasi-static analyzer. 33 .

[0091] Table 1: Performance test results of slurry and 3D printing ceramic materials

[0092] Table 2: Sedimentation rate test results

[0093] As can be seen from Table 1 and Table 2, the slurries prepared by the formula and method of the present invention in Examples 1 to 3 have lower viscosity, larger slice thickness, and strong photocuring ability; and the ceramic materials prepared by 3D printing thereof have good piezoelectric properties (d 33 ).

[0094] In the slurry of Comparative Example 1, only difunctional aliphatic polyurethane acrylate is used as the free radical photosensitive resin, the slurry has a high viscosity, a slow curing speed, and a low molding strength. The piezoelectric performance of the ceramic material after printing is significantly reduced compared with that of Example 1; in Comparative Example 2, only trifunctional aliphatic polyurethane acrylate is used as the free radical photosensitive resin, and the slice thickness and final printing performance of the slurry are also reduced compared with that of Example 1; in Comparative Example 3, only hexafunctional aliphatic polyurethane acrylate is used as the free radical photosensitive resin. The viscosity of the slurry is too low, and the shrinkage rate after curing is high, resulting in a decrease in printing accuracy. The piezoelectric performance of the ceramic material after printing is significantly reduced compared with that of Example 1.

[0095] In Comparative Example 4, no toner is added to the slurry, and the KNN powder has a large absorbance, which adversely affects the photocuring of the resin. Therefore, the slice thickness and the piezoelectric performance of the sample are significantly reduced compared with those in Example 1.

[0096] In the slurry of Comparative Example 5, adhesion promoter A-171 is used instead of the adhesion promoter in the present invention. Since the content of silane coupling agent A-171 is lower and has a greater negative impact on curing, the slurry slice thickness (curing effect decreases) and the piezoelectric performance of the final print are significantly reduced compared with that in Example 1.

[0097] In Comparative Example 6, no anti-settling agent was added to the slurry, and the sedimentation rate of the powder was significantly improved compared with that in Example 1. The sedimentation rate after 30 days exceeded 5%, and the shelf life of the slurry was shortened. In Comparative Example 7, fumed silica was used as an anti-settling agent. Although the sedimentation rate of the powder could be controlled at a lower level, the viscosity of the slurry increased significantly, affecting its photocuring performance, and the piezoelectric performance of the sample finally obtained was significantly reduced.

[0098] In Comparative Example 8, the type of diluent was changed, and HEMA was used as the diluent. Due to its very low viscosity, good flexibility, and only monofunctionality, the curing effect was poor, resulting in a significant decrease in the photocuring performance of the slurry and the piezoelectric performance of the sample compared with Example 1.

Claims

1. A lead-free piezoelectric ceramic slurry for DLP photocuring 3D printing, characterized in that: The components include, by weight: 50 to 75 parts of coupling agent modified potassium sodium niobate powder, 20 to 36.5 parts of free radical photosensitive resin, 10 to 15 parts of diluent, 1 to 2 parts of free radical initiator, 1 to 2 parts of dispersant, 0.5 to 1.5 parts of anti-settling agent, 0.3 to 1 parts of defoaming agent, 0.1 to 1 parts of adhesion promoter, and 0.1 to 1 parts of toner; The free radical photosensitive resin includes difunctional aliphatic polyurethane acrylate, trifunctional aliphatic polyurethane acrylate and 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 coupling agent and BYK-410; The adhesion promoter is at least one of 2-methyl-2-acrylic acid-2-hydroxyethyl ester phosphate, hydroxyethyl methacrylate phosphate, and CD9051; The toner is liquid nano white UV pigment.

2. The lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing according to claim 1 is characterized in that: The free radical initiator is selected from at least one of 1-hydroxycyclohexyl phenyl ketone, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphonate, and 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]-1-propanone.

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

4. The lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing according to claim 1, characterized in that: The defoaming agent is selected from at least one of silicones, surfactants and paraffins.

5. The lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing according to claim 1, characterized in that: The preparation method of the coupling agent modified potassium sodium niobate powder is as follows: A) grinding the potassium sodium niobate powder and adding it to a mixed solution of hydrogen peroxide and anhydrous ethanol to react to obtain hydroxylated potassium sodium niobate powder; B) reacting the hydroxylated potassium sodium niobate powder with a silane coupling agent to obtain the coupling agent modified potassium sodium niobate powder.

6. The lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing according to claim 5, characterized in that: In step A), the potassium sodium niobate powder is sand-ground 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 obtained suspension is centrifuged and washed after stirring for 8-10 hours to obtain hydroxylated potassium sodium niobate powder; the mass ratio of the sand-ground potassium sodium niobate powder to the hydrogen peroxide and anhydrous ethanol is 200-300:30-40:

500.

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

8. The lead-free piezoelectric ceramic slurry for DLP light-curing 3D printing according to claim 5 or 6, characterized in that: In step B), a silane coupling agent is added to the hydroxylated potassium sodium niobate powder, ultrasonically treated for 30 to 40 minutes, then heated to 95 to 105° C. for 1 to 2 hours, centrifuged, washed, and dried to obtain the coupling agent-modified potassium sodium niobate powder; the mass ratio of the hydroxylated potassium sodium niobate powder to the silane coupling agent is 200 to 300:

2.

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

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

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