A nano-ceramic slurry for light-curing molding and a method for preparing the same

Abstract

The application relates to the technical field of ceramic slurry, in particular to a nano ceramic slurry for light-curing forming and a preparation method thereof. The application provides a nano ceramic slurry with high solid content and low viscosity, which comprises 35wt%-90wt% ceramic powder, 10wt%-65wt% photosensitive resin, 2wt%-5wt% dispersant of the mass of the ceramic powder and 1wt%-5wt% sintering aid of the mass of the photosensitive resin. The ceramic slurry prepared by combining mechanical mixing with ball milling has a solid content as high as 60.21vol% and a viscosity as low as 24778 mPa.s. The low viscosity is favorable for the flattening of the slurry in the printing process, improves the final printing quality, the high solid content can reduce the cracking problem of the ceramic embryo in the subsequent debinding and sintering process, and improves the ceramic density.

Description

Technical Field

[0001] This invention relates to the field of ceramic slurry technology, and more specifically to a nano-ceramic slurry for photocuring molding and its preparation method. Background Technology

[0002] Ceramics, with their high melting point, high hardness, good corrosion resistance, good oxidation resistance, and wear resistance, are widely used in electronics, machinery, chemicals, and medical fields. However, due to the inherent brittleness and hardness of ceramic materials, traditional molding methods are difficult, thus limiting the fabrication of complex shapes and structures. Additive manufacturing can produce ceramic parts with complex structures, and photopolymerization technology is an advanced technology widely used in additive manufacturing, offering highly precise molding capabilities and efficient material utilization. The photopolymerization process is as follows: First, model slices are imported into a printer, and ultraviolet light is used to solidify the slurry layer by layer to obtain a preliminary ceramic preform. Then, a debinding and sintering process is performed to remove organic components and densify the part, thus obtaining the final part. This process significantly shortens the production cycle and has certain advantages in manufacturing high-precision complex structural parts.

[0003] The ceramic slurry used in photopolymer printing should possess certain rheological properties, photosensitivity, and stability, with a solid content of no less than 40 vol%. As the solid content increases, the shrinkage and deformation of ceramic parts during the printing and sintering process decreases, which is beneficial to the surface forming quality of the parts. However, excessively high solid content in the ceramic slurry can also increase its viscosity, making it less fluid. Research on the rheological properties of ceramic slurries, such as the invention patent with publication number CN116477929A, discloses a ceramic slurry and its preparation method. The prepared slurry has low viscosity, but its solid content is only 50.13 vol%, which is not conducive to subsequent debinding and sintering, and easily leads to cracking. The ceramic slurry used for photopolymer printing consists of resin and ceramic particles. During the photopolymerization, debinding, and sintering processes, the resin is gradually removed. The parts undergo a certain degree of deformation during these processes, resulting in a decrease in dimensional accuracy. The higher the solid content of the ceramic slurry, the smaller the shrinkage rate during the entire printing process. In addition, the higher the density of the prepared parts, the higher the surface accuracy. Achieving a ceramic slurry with high solid content and low viscosity remains a significant challenge.

[0004] The main factor affecting solid content and viscosity is the dispersion of ceramic powder in the resin system. Micron-sized ceramic powders, due to their small surface area, are easier to disperse in resin systems compared to nano-sized powders. However, when the prepared ceramic slurry is irradiated with projected light, severe scattering and reflection occur, resulting in poor photocuring properties. Furthermore, it tends to stratify when stationary, exhibiting poor stability and poor dimensional accuracy in the printed ceramic parts. Nano-sized powders, on the other hand, are prone to agglomeration, making it difficult to mix evenly with the resin during slurry preparation, significantly increasing the slurry viscosity. However, during the sintering of nano-ceramic parts, due to their small particle size and high driving force, sintering is rapid, resulting in high density and good performance of the ceramic parts. Therefore, exploring nano-ceramic slurries with high solid content and low viscosity is crucial for promoting the application of nano-ceramic materials. Summary of the Invention

[0005] This invention provides a nano-ceramic slurry for photocuring and its preparation method, with the aim of increasing the solid content of the ceramic slurry while maintaining its low viscosity.

[0006] The above objectives are achieved through the following technical solutions:

[0007] A ceramic slurry for photocuring comprises 35wt%-90wt% ceramic powder, 10wt%-65wt% photosensitive resin, 2%-5% dispersant by weight of ceramic powder, and 1%-5% sintering aid by weight of photosensitive resin.

[0008] The mass ratio of ceramic powder to photosensitive resin is 0.2-9:1.

[0009] The ceramic powder includes one or more of the following: alumina, aluminum nitride, silicon nitride, silicon carbide, zirconium oxide, yttrium oxide, hydroxyapatite, and barium tetratitanate.

[0010] The photosensitive resins mentioned include oligomers, monomers, and photoinitiators.

[0011] The oligomer content in the photosensitive resin is 3wt%-30wt%, the monomer content is 62wt%-95wt%, and the photoinitiator content is 2wt%-8wt%.

[0012] The oligomers are epoxy acrylate resin and polyurethane acrylate resin in a mass ratio of 1-5:1, the monomers are 1,6-ethylene glycol diacrylate, tripropylene glycol diacrylate and trimethylolpropane triacrylate in a mass ratio of 1-8:1:1, and the photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine.

[0013] The dispersants include polycaprolactone polyol polymer dispersants and polycarboxylate ammonium salt dispersants with a mass ratio of 1:0.1-0.2.

[0014] A method for preparing a ceramic slurry for photocuring includes the following steps:

[0015] Step 1: Mix epoxy acrylate resin and polyurethane acrylate resin to obtain a mixed resin;

[0016] 1,6-ethylene glycol diacrylate tripropylene glycol diacrylate and trimethylolpropane triacrylate are mixed to obtain a mixed monomer. The mixed monomer, the mixed resin and TPO photoinitiator are mixed to obtain a photosensitive resin.

[0017] Step 2: Ceramic slurry is prepared by mixing ceramic powder with a mass fraction of 35wt%-90wt%, photosensitive resin with a mass fraction of 10wt%-65wt%, polycaprolactone polyol polymer dispersant with a mass fraction of 2%-5% of ceramic powder, and polycarboxylate ammonium salt dispersant with a mass fraction of 2%-5% of ceramic powder.

[0018] The beneficial effects of the nano-ceramic slurry for photocuring molding and its preparation method of the present invention are as follows:

[0019] This invention combines a polycaprolactone polyol polymer dispersant with steric hindrance effect and a polycarboxylate ammonium salt dispersant with electrostatic stabilizing effect to form a binary composite dispersant. Therefore, the ceramic slurry prepared by this invention maintains low viscosity while having a high solids content. The solids content is as high as 60.214 vol%, and the viscosity is as low as 24778 mPa·s. The low viscosity is beneficial to the leveling of the slurry during the printing process and improves the final printing quality. The high solids content can reduce the cracking problem of the ceramic preform in the subsequent debinding and sintering process and improve the density of the ceramic. Attached Figure Description

[0020] Figure 1 This is a process diagram for preparing the ceramic slurry of the present invention;

[0021] Figure 2 These are comparison images of the ceramic parts prepared in Example 1 of this invention before and after sintering;

[0022] Figure 3 This is a graph showing the relationship between the solid content and viscosity of ceramic slurry. Detailed Implementation

[0023] A process for preparing a ceramic slurry, with reference to Figure 1 Example 1 includes the following steps:

[0024] Step 1: Transfer 12g of epoxy acrylate resin and 10g of polyurethane acrylate resin into a 500ml beaker, and add 31g of 1,6-ethylene glycol diacrylate, 5.5g of tripropylene glycol diacrylate, 5.5g of trimethylolpropane triacrylate and 0.84g of TPO photoinitiator. Place the beaker in an ultrasonic cleaner at 40℃ and sonicate for 1 hour to obtain the photosensitive resin.

[0025] Step 2: Add 18g of ceramic powder, 32g of photosensitive resin, 0.54g of polycaprolactone polyol polymer dispersant, 0.092g of ammonium polycarboxylate dispersant, 0.54g of MgO powder, and 40g of alumina milling balls to a ball mill jar. The ceramic powder has a particle size of 100-300nm. Place the ball mill jar in a ball mill and ball mill to obtain a ceramic slurry.

[0026] The viscosity of the ceramic slurry in Example 1 was measured using an NDJ-8S digital display viscometer:

[0027] The specific method is as follows: At 23℃, pour the slurry into a beaker, connect rotor No. 1, and rotate the side test head height adjustment nut to lower the test head with the rotor until it reaches the slurry surface, covering the upper surface of the rotor. Adjust the rotation speed to 6 rpm, and conduct the test at 10% < torque > 80%. The measured viscosity is 170 mPa·s.

[0028] The solid content was determined using conventional methods, and the solid content of the ceramic slurry was 10.00 vol%.

[0029] The slurry obtained in Example 1 was used to 3D print an alumina preform, and the resulting alumina preform was subjected to a subsequent debinding and sintering process.

[0030] like Figure 2 As shown in the comparison image before and after sintering, it can be seen from the image that the sintered product has no cracks.

[0031] Example 2 is the same as Example 1, except for the following content:

[0032] The contents are: 11g of epoxy acrylate resin, 9g of polyurethane acrylate resin, 29.4g of 1,6-ethylene glycol diacrylate, 5.3g of tripropylene glycol diacrylate, 5.3g of trimethylolpropane triacrylate, and 0.8g of TPO photoinitiator.

[0033] The ceramic powder is 20g, the photosensitive resin is 30g, the polycaprolactone polyol polymer dispersant is 0.59g, the polycarboxylate ammonium salt dispersant is 0.1g, and the MgO powder is 0.5g.

[0034] The ceramic slurry of Example 2 was tested under the same conditions as in Example 1, and the viscosity was measured to be 206 mPa·s, with a solid content of 15.71 vol%.

[0035] Example 3 is the same as Example 1, except for the following content:

[0036] The contents are: 10g of epoxy acrylate resin, 8g of polyurethane acrylate resin, 26.2g of 1,6-ethylene glycol diacrylate, 4.9g of tripropylene glycol diacrylate, 4.9g of trimethylolpropane triacrylate, and 0.74g of TPO photoinitiator.

[0037] The ceramic powder is 23g, the photosensitive resin is 27g, the polycaprolactone polyol polymer dispersant is 0.67g, the polycarboxylate ammonium salt dispersant is 0.11g, and the MgO powder is 0.44g.

[0038] The ceramic slurry of Example 3 was tested under the same conditions as in Example 1, and the viscosity was measured to be 212 mPa·s, with a solid content of 20.53 vol%.

[0039] Example 4 is the same as Example 1, except for the following content:

[0040] The contents are: 9g of epoxy acrylate resin, 7g of polyurethane acrylate resin, 24.6g of 1,6-ethylene glycol diacrylate, 4.7g of tripropylene glycol diacrylate, 4.7g of trimethylolpropane triacrylate, and 0.7g of TPO photoinitiator.

[0041] The ceramic powder is 25g, the photosensitive resin is 25g, the polycaprolactone polyol polymer dispersant is 0.72g, the polycarboxylate ammonium salt dispersant is 0.12g, and the MgO powder is 0.4g.

[0042] The ceramic slurry of Example 4 was tested under the same conditions as in Example 1, and the viscosity was measured to be 281 mPa·s, with a solid content of 25.26 vol%.

[0043] Example 5 is the same as Example 1, except for the following content:

[0044] The contents are: 8g of epoxy acrylate resin, 6g of polyurethane acrylate resin, 18.2g of 1,6-ethylene glycol diacrylate, 3.9g of tripropylene glycol diacrylate, 3.9g of trimethylolpropane triacrylate, and 0.6g of TPO photoinitiator.

[0045] The ceramic powder is 30g, the photosensitive resin is 20g, the polycaprolactone polyol polymer dispersant is 0.84g, the polycarboxylate ammonium salt dispersant is 0.14g, and the MgO powder is 0.3g.

[0046] The ceramic slurry of Example 5 was tested under the same conditions as in Example 1, and the viscosity was measured to be 541 mPa·s, with a solid content of 30.61 vol%.

[0047] Example 6 is the same as Example 1, except for the following content:

[0048] The contents are: 7g of epoxy acrylate resin, 5g of polyurethane acrylate resin, 15g of 1,6-ethylene glycol diacrylate, 3.5g of tripropylene glycol diacrylate, 3.5g of trimethylolpropane triacrylate, and 0.54g of TPO photoinitiator.

[0049] The ceramic powder is 33g, the photosensitive resin is 17g, the polycaprolactone polyol polymer dispersant is 0.92g, the polycarboxylate ammonium salt dispersant is 0.15g, and the MgO powder is 0.24g.

[0050] The ceramic slurry of Example 6 was tested under the same conditions as in Example 1, and the viscosity was measured to be 829 mPa·s, with a solid content of 35.22 vol%.

[0051] Example 7 is the same as Example 1, except for the following content:

[0052] The contents are: 6g of epoxy acrylate resin, 4g of polyurethane acrylate resin, 13.4g of 1,6-ethylene glycol diacrylate, 3.3g of tripropylene glycol diacrylate, 3.3g of trimethylolpropane triacrylate, and 0.5g of TPO photoinitiator.

[0053] The ceramic powder is 35g, the photosensitive resin is 15g, the polycaprolactone polyol polymer dispersant is 0.97g, the polycarboxylate ammonium salt dispersant is 0.16g, and the MgO powder is 0.2g.

[0054] The ceramic slurry of Example 7 was tested under the same conditions as in Example 1, except that the rotation speed was adjusted to 1.5 rpm. The viscosity was measured to be 1467 mPa·s and the solid content of the ceramic slurry was 40.97 vol.

[0055] Example 8 is the same as Example 1, except for the following content:

[0056] The contents are: 5g of epoxy acrylate resin, 3g of polyurethane acrylate resin, 10.2g of 1,6-ethylene glycol diacrylate, 2.9g of tripropylene glycol diacrylate, 2.9g of trimethylolpropane triacrylate, and 0.44g of TPO photoinitiator.

[0057] The ceramic powder is 38g, the photosensitive resin is 12g, the polycaprolactone polyol polymer dispersant is 1.04g, the polycarboxylate ammonium salt dispersant is 0.17g, and the MgO powder is 0.14g.

[0058] The ceramic slurry of Example 8 was tested under the same conditions as in Example 1, except that the rotation speed was adjusted to 3 rpm. The viscosity was measured to be 2489 mPa·s and the solid content of the ceramic slurry was 45.60 vol.

[0059] Example 9 is the same as Example 1, except for the following content:

[0060] The contents are: 4g of epoxy acrylate resin, 2g of polyurethane acrylate resin, 8.6g of 1,6-ethylene glycol diacrylate, 2.5g of tripropylene glycol diacrylate, 2.5g of trimethylolpropane triacrylate, and 0.4g of TPO photoinitiator.

[0061] The ceramic powder is 40g, the photosensitive resin is 10g, the polycaprolactone polyol polymer dispersant is 1.09g, the polycarboxylate ammonium salt dispersant is 0.18g, and the MgO powder is 0.1g.

[0062] The ceramic slurry of Example 9 was tested under the same conditions as in Example 1, except that the rotation speed was adjusted to 3 rpm. The viscosity was measured to be 6962 mPa·s and the solid content of the ceramic slurry was 50.44 vol.

[0063] Example 10 is the same as Example 1, except for the following content:

[0064] The contents are: 3.5g of epoxy acrylate resin, 1.5g of polyurethane acrylate resin, 5.4g of 1,6-ethylene glycol diacrylate, 2.1g of tripropylene glycol diacrylate, 2.1g of trimethylolpropane triacrylate, and 0.35g of TPO photoinitiator.

[0065] The ceramic powder is 42.5g, the photosensitive resin is 7.5g, the polycaprolactone polyol polymer dispersant is 1.15g, the polycarboxylate ammonium salt dispersant is 0.19g, and the MgO powder is 0.05g.

[0066] The ceramic slurry of Example 10 was tested under the same conditions as in Example 1, except that the rotation speed was adjusted to 3 rpm. The viscosity was measured to be 9508 mPa·s and the solid content of the ceramic slurry was 55.79 vol.

[0067] Example 11 is the same as Example 1, except for the following content:

[0068] The contents are: 2.7g of epoxy acrylate resin, 0.7g of polyurethane acrylate resin, 2.68g of 1,6-ethylene glycol diacrylate, 1.76g of tripropylene glycol diacrylate, 1.76g of trimethylolpropane triacrylate, and 0.3g of TPO photoinitiator.

[0069] The ceramic powder is 45g, the photosensitive resin is 5g, the polycaprolactone polyol polymer dispersant is 1.22g, the polycarboxylate ammonium salt dispersant is 0.2g, and the MgO powder is 0.02g.

[0070] The ceramic slurry of Example 11 was tested under the same conditions as in Example 1, except that the rotation speed was adjusted to 3 rpm. The viscosity was measured to be 24788 mPa·s and the solid content of the ceramic slurry was 60.21 vol.

[0071] For easy comparison, refer to Table 1 below. When the ceramic slurry has a high solids content, it can still maintain a low viscosity.

[0072] Example 1 Example 5 Example 11 Epoxy acrylate resin (g) 12 8 2.7 Polyurethane acrylic resin (g) 10 6 0.7 1,6-Ethylene glycol diacrylate (g) 31 21.4 2.68 Tripropylene glycol diacrylate (g) 5.5 4.3 1.76 Trimethylolpropane triacrylate (g) 5.5 4.3 1.76 TPO photoinitiator (g) 0.84 0.64 0.3 Photosensitive resin (g) 32 22 5 Ceramic powder (g) 18 28 45 Polycaprolactone polyol polymer dispersant (g) 0.54 0.72 1.22 Ammonium polycarboxylate dispersant (g) 0.092 0.12 0.2 MgO powder (g) 0.54 0.4 0.02 Viscosity (mPa.s) 170 541 24788 Solid content (vol%) of ceramic slurry 10.00 30.61 60.21

Claims

1. A nano-ceramic slurry for photocuring, comprising 35wt%-90wt% ceramic powder, 10wt%-65wt% photosensitive resin, 2%-5% dispersant by weight of ceramic powder, and 1%-5% sintering aid by weight of photosensitive resin, characterized in that: The photosensitive resin comprises oligomers, monomers, and a photoinitiator. The oligomers are epoxy acrylate resins and polyurethane acrylate resins. The monomers are 1,6-ethylene glycol diacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate. The photoinitiator is 2,4,6-trimethylbenzoyl-diphenylphosphine. The dispersant comprises polycaprolactone polyol polymer dispersant and polycarboxylate ammonium salt dispersant.

2. The nano-ceramic slurry for photocuring according to claim 1, characterized in that: The mass ratio of the ceramic powder to the photosensitive resin is 0.2-9:

1.

3. The nano-ceramic slurry for photocuring according to claim 1, characterized in that: The ceramic powder includes one or more of the following: alumina, aluminum nitride, silicon nitride, silicon carbide, zirconium oxide, yttrium oxide, hydroxyapatite, and barium tetratitanate.

4. The nano-ceramic slurry for photocuring according to claim 1, characterized in that: The oligomer has a mass fraction of 3wt%-30wt% in the photosensitive resin, the monomer has a mass fraction of 62wt%-95wt% in the photosensitive resin, and the photoinitiator has a mass fraction of 2wt%-8wt% in the photosensitive resin.

5. The nano-ceramic slurry for photocuring according to claim 4, characterized in that: The mass ratio of the epoxy acrylate resin to the polyurethane acrylate resin is 1-5:

1.

6. The nano-ceramic slurry for photocuring according to claim 4, characterized in that: The mass ratio of 1,6-ethylene glycol diacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate is 1-8:1:

1.

7. The nano-ceramic slurry for photocuring according to claim 1, characterized in that: The mass ratio of the polycaprolactone polyol polymer dispersant to the polycarboxylic acid ammonium salt dispersant is 1:0.1-0.

2.

8. The nano-ceramic slurry for photocuring according to claim 1, characterized in that: The particle size of the ceramic powder is 100-300 nm.

9. A method for preparing a nano-ceramic slurry for photocuring molding, characterized in that, Includes the following steps: Step 1: Mix epoxy acrylate resin and polyurethane acrylate resin at a mass ratio of 1-5:1 to obtain a mixed resin; mix 1,6-ethylene glycol diacrylate, tripropylene glycol diacrylate, and trimethylolpropane triacrylate at a mass ratio of 1-8:1:1 to obtain a mixed monomer; mix the mixed monomer, the mixed resin, and TPO photoinitiator to obtain a photosensitive resin, wherein the TPO photoinitiator accounts for 2wt%-8wt% of the mass of the photosensitive resin; Step 2: Mix ceramic powder with a mass fraction of 35wt%-90wt%, photosensitive resin with a mass fraction of 10wt%-65wt%, polycaprolactone polyol polymer dispersant with a mass fraction of 2%-5% of the ceramic powder, polycarboxylate ammonium salt dispersant with a mass fraction of 2%-5% of the ceramic powder, and sintering aid with a mass fraction of 1%-5% of the photosensitive resin to prepare a ceramic slurry.

10. The method for preparing nano-ceramic slurry for photocuring according to claim 9, wherein the mixing method in step two is ball milling.

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