Light-cured precious metal paste capable of resisting paste hanging on surface of green body and preparation method of green body of light-cured precious metal paste

Abstract

The invention discloses light-cured precious metal slurry for resisting slurry hanging on the surface of a green body and a preparation method of the green body, and belongs to the technical field of additive manufacturing. The slurry comprises, by mass, 70%-89% of precious metal powder, 3%-18% of an active diluent, 2%-10% of an oligomer, 0.5%-1.5% of a photoinitiator, 1%-4% of a dispersant and 0.8%-2.5% of an anti-hanging functional additive, wherein the anti-hanging functional additive is composed of hydrogenated castor oil and fluorine-containing silane according to the ratio of 1: 0.06-0.3. The preparation method comprises the following steps: preparing a photosensitive premixed solution, adding a dispersing agent and an anti-sticking additive to obtain a mixed solution, homogenizing and mixing the mixed solution with noble metal powder to obtain slurry, performing'high-energy short-time 'exposure (ultraviolet light energy is 120-160mJ / cm and time is 3-6s) printing, and cleaning with alcohol or absolute ethyl alcohol to obtain a green body; through cooperative regulation of rheological and interface characteristics, surface slurry hanging is remarkably reduced, the precision of the green body is improved, the cleaning time is saved, the utilization rate of precious metal is increased, and economic benefits and environment friendliness are achieved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of additive manufacturing, and particularly relates to a light-cured precious metal paste resistant to green body surface paste sticking and a green body preparation method thereof. BACKGROUND

[0002] Precious metals (such as gold, silver, platinum, palladium and their alloys) are widely used in jewelry, high-end watches, electronics and electrical appliances (such as contacts and wires), dental and medical devices (such as crowns and implants), and investment and collection due to their unique high chemical stability, excellent electrical and thermal conductivity, attractive metallic luster, and valuable currency and collection value. However, the raw materials of precious metals are extremely expensive, and the processing and manufacturing process puts high requirements on material utilization and forming precision. Currently, the manufacturing of complex structure parts of precious metals mainly relies on traditional lost-wax casting technology, but this technology has many disadvantages: complex process, long production cycle, limited design freedom, difficulty in forming complex structures, low material utilization, poor forming precision and surface quality, etc.

[0003] As a new forming technology, light-cured additive manufacturing of precious metals has shown significant advantages in solving the pain points of traditional lost-wax casting and has become the preferred process for high-end precious metal products. This technology is particularly suitable for the preparation of precious metal products containing complex structures such as high porosity and nesting, and the complexity of the products is not directly related to the manufacturing cost, successfully overcoming the disadvantages of high cost and difficulty in preparing complex structures in traditional technology. In the light-cured additive manufacturing technology of precious metals, the quality of the green body is the basis for the success of the process. Patent CN116230290A proposes a light-cured silver paste for additive manufacturing and a preparation method thereof, which effectively solves the problems of silver powder stability and dispersibility. However, the current technology still faces a major challenge - green body surface paste sticking, i.e. excessive adhesion of uncured paste to the surface of the green body, resulting in material waste, blurred details, dimensional deviation and surface defects. This problem seriously restricts the application and development of light-cured additive manufacturing technology in the field of precise manufacturing of precious metals. SUMMARY

[0004] The application provides a light-cured precious metal paste resistant to green body surface paste sticking and a green body preparation method thereof, aiming to solve the technical problem of green body surface paste sticking. By optimizing the synergistic effect of paste components and process parameters, the residual uncured paste on the surface of the green body is effectively inhibited.

[0005] To achieve the above-mentioned purpose, the application provides a light-cured precious metal paste resistant to green body surface paste sticking, which comprises, by mass ratio, 70% to 89% of precious metal powder, 3% to 18% of active diluent, 2% to 10% of oligomer, 0.5% to 1.5% of photoinitiator, 1% to 4% of dispersant, and 0.8% to 2.5% of anti-paste sticking functional additive.

[0006] In an embodiment, the noble metal powder is selected from one of gold, silver, platinum, palladium, rhodium, iridium, osmium.

[0007] In an embodiment, the reactive diluent is selected from one or more combinations of caprolactone acrylate, lauryl acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate.

[0008] In an embodiment, the oligomer is selected from one or more combinations of epoxy acrylate, urethane acrylate, polyester acrylate, acrylated acrylate, bisphenol A epoxy acrylate.

[0009] In an embodiment, the dispersant is selected from one or more combinations of BYK-110, BYK-111, BYK-163, BYK-168, BYK-LPN21116, BYK-LPN 21117, Solsperse 32000, Solsperse 39000.

[0010] In an embodiment, the photoinitiator is selected from one or more combinations of benzoin methyl ether, benzophenone, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, (2,4,6-trimethylbenzoyl) diphenylphosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide.

[0011] In an embodiment, the anti-slumping functional additive is composed of hydrogenated castor oil and fluorine-containing silane, wherein the fluorine-containing silane is 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane, and the mass ratio of the hydrogenated castor oil and the fluorine-containing silane is 1:0.06-0.3.

[0012] A method for preparing a photo-cured noble metal green body with anti-slumping on the surface of the green body, comprising the following steps: S1, dissolving a photoinitiator in a reactive diluent according to the mass percentage, ultrasonic treatment until completely dissolved, then adding an oligomer, stirring uniformly to form a photosensitive premix; S2, adding a dispersant to the photosensitive premix according to the mass percentage and mixing, after sufficient mixing, adding an anti-slumping functional additive, continuing to stir until completely dissolved to form a mixed solution; S3, transferring the mixed solution to a homogenizer tank, adding a noble metal powder to the homogenizer tank according to the mass percentage, starting the homogenizer to mix, and obtaining a photo-cured noble metal slurry after mixing is completed; S4, loading the prepared photo-cured noble metal slurry into a printer hopper, and setting the parameters of the printer; S5, after the printer parameter setting is completed, a printing program is started, and a light-cured precious metal blank is obtained after printing is completed; S6, the light-cured precious metal blank is taken out and soaked in a cleaning liquid to remove residual slurry on the surface, and a light-cured precious metal green body is obtained after the residual slurry is removed.

[0013] In an embodiment, in step S4, the printer parameters adopt "high energy and short time" exposure, the ultraviolet energy is 120 mJ / cm2-160 mJ / cm2, and the exposure time is 3 s-6 s, so that the surface layer slurry is completely cured instantaneously to form a dense isolation layer.

[0014] In an embodiment, in step S6, the cleaning liquid is selected from one of alcohol and anhydrous ethanol.

[0015] Compared with the prior art, the application has the following beneficial effects: 1. Synergistically regulating rheology and interface characteristics to significantly improve slurry performance and green body quality Hydrogenated castor oil as a high-efficiency thixotropic agent can build a three-dimensional hydrogen bond network in the slurry, giving it excellent high-shear thinning and low-shear high-viscosity characteristics. In the high-shear process such as doctor blade paving, the viscosity of the slurry rapidly decreases, ensuring smooth paving and uniform layer thickness. In the stationary or low-shear state, the viscosity quickly recovers, effectively inhibiting the precipitation of precious metal powder, ensuring the stability and uniformity of the slurry throughout the printing process, and laying a foundation for the preparation of high-quality green bodies. Fluorine-containing silane acts on the interface due to its unique molecular structure: the silane end (-SiOR3 or -SiCl3) forms a firm covalent bond with the hydroxyl group on the surface of the precious metal powder through hydrolysis, building a dense fluorocarbon molecular film with ultra-low surface energy. This film greatly reduces the wettability of the powder surface, significantly hindering the adhesion of uncured slurry, and its slurry-repellent performance surpasses that of traditional surfactants or single dispersants. Hydrogenated castor oil and fluorine-containing silane complement each other and synergistically enhance each other's functions - the former builds a network structure in the bulk phase to block the penetration and residue of the slurry, and the latter forms a slurry-repellent layer on the particle interface to actively repel the adhesion of the slurry. The combination of the two makes the excess slurry on the surface of the green body after printing quickly slide off under the action of gravity or very slight cleaning, thereby obtaining a high-precision green body with clear details and clean surface.

[0016] 2. Enhancing the stability and printing suitability of the slurry The thixotropic network formed by hydrogenated castor oil effectively locks the metal powder, which is difficult to settle even after a long period of standing, significantly extending the storage life of the slurry. Before use, only simple stirring is needed to restore the uniform state, avoiding printing failures caused by uneven settlement, and greatly improving material utilization. Under the action of shear thinning effect, the slurry quickly levels off at each layer printing, forming a smooth and uniform thin layer, ensuring consistent curing quality of each layer and eliminating interlayer defects.

[0017] 3. Simplifying post-processing procedures and improving production efficiency Traditional green body cleaning needs to rely on long time high frequency ultrasonic treatment or a large amount of organic solvent flushing, which consumes time and materials and is easy to damage fragile structure. The present application greatly simplifies the cleaning process, and the green body surface is almost free of slurry, which can meet the cleaning requirements only by mild cleaning conditions (such as short soaking and rinsing), and the cleaning time is saved by more than 50%, and the solvent consumption is significantly reduced. Reduce the dependence on high intensity ultrasonic cleaning, and fundamentally eliminate the risk of green body microstructure fracture or internal crack caused by ultrasonic energy.

[0018] 4. Highlight the environmental and economic benefits The mild cleaning process makes the residual slurry content in the recycled cleaning liquid very low, which is easier to purify and recycle, and further improves the utilization rate of precious metals. The simplified post-treatment process significantly reduces the energy consumption of water, electricity, solvent and equipment, which is in line with the development concept of green manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0020] Figure 1 The overall schematic diagram of the light-cured high-precision metal green body preparation method provided by the present application is shown. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor also belong to the scope of protection of the present application.

[0022] Reference Figure 1 As shown, the light-cured precious metal slurry provided by the present application prevents the green body surface from being coated with slurry, and the precious metal slurry comprises, by mass ratio, 70% to 89% of precious metal powder, 3% to 18% of active diluent, 2% to 10% of oligomer, 0.5% to 1.5% of photoinitiator, 1% to 4% of dispersant and 0.8% to 2.5% of anti-slurry coating functional additive.

[0023] The noble metal powder is selected from one of gold, silver, platinum, palladium, rhodium, iridium and osmium. The active diluent is selected from one or more combinations of caprolactone acrylate, lauryl acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tricyclodecane dimethanol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate and dipentaerythritol hexaacrylate. The oligomer is selected from one or more combinations of epoxy acrylate, polyurethane acrylate, polyester acrylate, acrylated acrylate and bisphenol A epoxy acrylate. The dispersant is selected from one or more combinations of BYK-110, BYK-111, BYK-163, BYK-168, BYK-LPN 21116, BYK-LPN 21117, Solsperse 32000 and Solsperse 39000. The photoinitiator is selected from one or more combinations of benzoin methyl ether, benzophenone, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide and phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide. The anti-slumping functional additive is composed of hydrogenated castor oil and fluorine-containing silane, wherein the fluorine-containing silane is 1H, 1H, 2H, 2H-perfluorooctyl triethoxysilane, and the mass ratio of the hydrogenated castor oil to the fluorine-containing silane is 1:0.06-0.3.

[0024] The application provides a method for preparing a green body of a light-cured noble metal with no slurry on the surface, comprising the following steps: S1, dissolving a photoinitiator in an active diluent according to the mass percentage, and ultrasonic treating until completely dissolved, then adding an oligomer and stirring uniformly to form a photosensitive premix; S2, adding a dispersant to the photosensitive premix according to the mass percentage and mixing, then adding an anti-slumping functional additive after sufficient mixing, and continuing to stir until completely dissolved to form a mixed solution; S3, transferring the mixed solution to a homogenizer tank, adding a noble metal powder to the homogenizer tank according to the mass percentage, starting the homogenizer to mix, and obtaining a light-cured noble metal slurry after mixing is completed; S4, loading the prepared light-cured noble metal slurry into a printer hopper, and setting printer parameters, wherein the printer parameters adopt “high energy and short time” exposure, the ultraviolet light energy is 120-160 mJ / cm², and the exposure time is 3-6 s, so that the surface layer slurry is completely cured instantaneously to form a dense isolation layer.

[0025] S5, after the printer parameter setting is completed, starting the printing program, and obtaining a light-cured noble metal green body after printing is completed; S6, taking out the light-cured noble metal blank and immersing it in a cleaning liquid to remove the residual slurry on the surface, and obtaining a light-cured noble metal green body after the residual slurry is removed. The cleaning liquid is selected from one of alcohol and anhydrous ethanol.

[0026] The application will be further described in conjunction with specific examples. It should be understood that the instruments and equipment used in the following examples are conventional in the art. The experimental methods in the following examples, for which no specific conditions are indicated, are generally performed under conventional conditions or under the conditions recommended by the manufacturers. The various raw materials used in the following examples are conventional commercially available products, unless otherwise specified, and are used in conventional specifications. In the specification of the application and in the following examples, unless otherwise specified, "%" means "percent by weight", "parts" means "parts by weight", and the ratio means "ratio by weight".

[0027] Example 1

[0028] 0.5% of a photoinitiator methyl benzoate and 0.5% of a photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide were respectively dissolved in 8% of an active diluent caprolactone acrylate and 4% of an active diluent lauryl acrylate, and ultrasonic treatment was performed to completely dissolve the photoinitiators. After the photoinitiators were completely dissolved, 3% of an oligomer polyurethane acrylate was added, and the uniform photoreactive premix was stirred.

[0029] Then, 1% of a dispersant BYK-110 and 1% of a dispersant BYK-163 were added to the prepared photoreactive premix, and stirred and mixed. After sufficient mixing, 1.8% of hydrogenated castor oil and fluorine-containing silane were added, and the mass ratio of the hydrogenated castor oil to the fluorine-containing silane was 1:0.6. After the hydrogenated castor oil and the fluorine-containing silane were completely dissolved by continuous stirring, a uniform and stable mixed solution was formed. The mixed solution was transferred to a homogenizer tank, 79.2% of silver powder was added to the homogenizer tank at the same time, and the silver powder was added in multiple small batches to avoid agglomeration. The homogenizer was started to mix the silver powder and the mixed solution uniformly. After uniform mixing, a light-cured silver slurry was obtained.

[0030] Finally, the light-cured silver slurry was loaded into a printer hopper, and after loading was completed, printing parameters were set, and the printing parameters were: ultraviolet energy 120 mJ / cm², exposure time 4 s. After the printing parameters were set, the printing program was started, and layer-by-layer printing was performed. After the layer-by-layer printing was completed, the light-cured silver blank with a small amount of slurry was taken out, the amount of slurry was 0.8 mg / cm², the light-cured silver blank was immersed in alcohol, and rinsed twice to completely remove the residual slurry on the surface. Finally, a light-cured silver green body with a clean surface and complete structure was obtained.

[0031] Example 2

[0032] 0.8% of the photoinitiator 2-isopropylthioxanthone, 0.6% of the photoinitiator phenyl bis(2,4,6-trimethylbenzoyl) phosphine oxide are respectively dissolved in 4% of the active diluent lauryl acrylate, 3% of the active diluent tricyclodecane dimethanol diacrylate, and the photoinitiator is completely dissolved by ultrasonic treatment. After the photoinitiator is completely dissolved, 3% of the oligomer polyurethane acrylate is added, and the mixture is stirred uniformly to obtain a photosensitive premix.

[0033] Subsequently, 2% of the dispersant BYK-163 and 2% of the dispersant Solsperse 39000 are added to the photosensitive premix, and the mixture is stirred. After the mixture is fully mixed, 2.5% of the hydrogenated castor oil and the fluorine-containing silane are added, and the mass ratio of the hydrogenated castor oil to the fluorine-containing silane is 1:0.3. The mixture is continuously stirred until the hydrogenated castor oil and the fluorine-containing silane are completely dissolved to form a uniform and stable mixture. The mixture is transferred to a homogenizing tank, 82.1% of platinum powder is added to the homogenizing tank, and the platinum powder needs to be added in multiple small batches to prevent agglomeration. The homogenizer is started to fully disperse and uniformly mix the platinum powder and the mixture to obtain a light-cured platinum slurry.

[0034] Finally, the light-cured platinum slurry is loaded into the printer hopper, and after the loading is completed, the printing parameters are set. The printing parameters of the printer are: ultraviolet energy 150 mJ / cm², exposure time 3 s. After the printing parameters are set, the printing program is started, and layer-by-layer printing is performed. After the layer-by-layer printing is completed, the light-cured platinum blank with a small amount of slurry is taken out, the amount of slurry is 1.0 mg / cm², the light-cured platinum blank is soaked in anhydrous ethanol, and rinsed twice to completely remove the residual slurry on the surface, and finally a clean and complete structure of the light-cured platinum green body is obtained.

[0035] Example Three

[0036] 0.8% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone, 0.7% of the photoinitiator (2,4,6-trimethylbenzoyl) diphenyl phosphine oxide are respectively dissolved in 12% of the active diluent tricyclodecane dimethanol diacrylate, 6% of the active diluent trimethylolpropane triacrylate, and the photoinitiator is completely dissolved by ultrasonic treatment. After the photoinitiator is completely dissolved, 5.5% of the oligomer epoxy acrylate is added, and the mixture is stirred uniformly to obtain a photosensitive premix.

[0037] Subsequently, 1.5% of dispersant BYK-168 and 1.5% of dispersant Solsperse 32000 were added to the photosensitive premix, and stirred and mixed. After sufficient mixing, 2% of hydrogenated castor oil and fluorine-containing silane were added, and the mass ratio of the hydrogenated castor oil to the fluorine-containing silane was 1:0.2. After the hydrogenated castor oil and the fluorine-containing silane were completely dissolved by continuous stirring, a uniform and stable mixed solution was formed. The mixed solution was transferred to a homogenizing tank, and 70% of gold powder was added to the homogenizing tank at the same time. The gold powder was added in small batches to prevent agglomeration. The homogenizer was started to stir to make the gold powder fully dispersed and uniformly mixed with the mixed solution. After uniform mixing, a photocured gold slurry was obtained.

[0038] Finally, the photocured gold slurry was loaded into the printer hopper. After loading was completed, the printing parameters were set, and the printing parameters were: ultraviolet energy 160 mJ / cm², exposure time 3 s. After the printing parameters were set, the printing program was started, and layer-by-layer printing was performed. After the layer-by-layer printing was completed, the photocured gold blank with a small amount of slurry was taken out, the amount of slurry was 0.9 mg / cm², the photocured gold blank was soaked in anhydrous ethanol, and rinsed twice to completely remove the residual slurry on the surface. Finally, a photocured gold green body with a clean surface and complete structure was obtained.

[0039] Example Four

[0040] 0.4% of a photoinitiator 2-isopropylthioxanthone and 0.4% of a photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone were respectively dissolved in 5% of an active diluent 1,6-hexanediol diacrylate and 3.3% of an active diluent dipentaerythritol hexaacrylate. Ultrasonic treatment was performed to completely dissolve the photoinitiators. After the photoinitiators were completely dissolved, 2% of an oligomer acrylated acrylate was added, and stirred uniformly to obtain a photosensitive premix.

[0041] Subsequently, 1.2% of a dispersant BYK-LPN 21116 and 1.2% of a dispersant Solsperse 32000 were added to the photosensitive premix, and stirred and mixed. After sufficient mixing, 1.5% of hydrogenated castor oil and fluorine-containing silane were added, and the mass ratio of the hydrogenated castor oil to the fluorine-containing silane was 1:0.1. After the hydrogenated castor oil and the fluorine-containing silane were completely dissolved by continuous stirring, a uniform and stable mixed solution was formed. The mixed solution was transferred to a homogenizing tank, and 85% of palladium powder was added to the homogenizing tank at the same time. The palladium powder was added in small batches to prevent agglomeration. The homogenizer was started to stir to make the palladium powder fully dispersed and uniformly mixed with the mixed solution. After uniform mixing, a photocured palladium slurry was obtained.

[0042] Finally, the photocured palladium slurry is loaded into the printer hopper, and after the loading is completed, the printing parameters are set, and the printing parameters are: ultraviolet energy 130 mJ / cm2, exposure time 5 s. After the printing parameter setting is completed, the printing program is started, and layer-by-layer printing is performed. After the layer-by-layer printing is completed, the photocured palladium blank with a small amount of slurry is taken out, the amount of slurry hanging is 0.8 mg / cm2, the photocured palladium blank is soaked in anhydrous ethanol, and rinsed twice to completely remove the residual slurry on the surface, and finally a photocured palladium green body with a clean surface and complete structure is obtained.

[0043] Example Five

[0044] 0.6% of the photoinitiator methyl benzoate and 0.6% of the photoinitiator 2-hydroxy-2-methyl-1-phenyl-1-propanone are respectively dissolved in 9% of the active diluent 1,6-hexanediol diacrylate and 5% of the active diluent bisphenol A epoxy acrylate, and ultrasonic treatment is performed to completely dissolve the photoinitiators. After the photoinitiators are completely dissolved, 4% of the oligomer bisphenol A epoxy acrylate is added, and after uniform stirring, a photosensitive premix liquid is obtained.

[0045] Subsequently, 2% of the dispersant BYK-LPN 21117 and 2% of the dispersant Solsperse 39000 are added to the photosensitive premix liquid, and stirring and mixing are performed. After sufficient mixing, 1.8% of hydrogenated castor oil and fluorine-containing silane are added, and the mass ratio of the hydrogenated castor oil to the fluorine-containing silane is 1:0.08. After the hydrogenated castor oil and the fluorine-containing silane are completely dissolved and a uniform and stable mixed liquid is formed, the mixed liquid is transferred to a homogenizing tank. At the same time, 75% of rhodium powder is added to the homogenizing tank in batches in a small amount to prevent agglomeration. The homogenizer is started to stir to uniformly disperse the rhodium powder in the mixed liquid. After uniform mixing, a photocured rhodium slurry is obtained.

[0046] Finally, the photocured rhodium slurry is loaded into the printer hopper, and after the loading is completed, the printing parameters are set, and the printing parameters are: ultraviolet energy 120 mJ / cm2, exposure time 4 s. After the printing parameter setting is completed, the printing program is started, and layer-by-layer printing is performed. After the layer-by-layer printing is completed, the photocured rhodium blank with a small amount of slurry is taken out, the amount of slurry hanging is 1 mg / cm2, the photocured rhodium blank is soaked in anhydrous ethanol, and rinsed twice to completely remove the residual slurry on the surface, and finally a photocured rhodium green body with a clean surface and complete structure is obtained.

[0047] It should be noted that hydrogenated castor oil as a high-efficiency thixotropic agent can form a three-dimensional hydrogen bond network in the slurry, giving the slurry excellent high-shear thinning and low-shear high-viscosity properties. In the high-shear process such as doctor blade laying, the viscosity of the slurry rapidly decreases, ensuring smooth laying and uniform layer thickness; while in the static or low-shear state, the viscosity quickly recovers, effectively inhibiting the sedimentation of noble metal powder, ensuring the stability and uniformity of the slurry throughout the printing process, laying the foundation for the preparation of high-quality green bodies. Fluorine-containing silane acts on the interface due to its unique molecular structure, and after the hydrolysis of its silane end (-SiOR3 or -SiCl3), it forms a firm covalent bond with the surface hydroxyl group of the noble metal powder, forming a dense fluorocarbon molecular film with ultra-low surface energy. This film greatly reduces the wettability of the powder surface, significantly hindering the adhesion of unsolidified slurry, and its slurry-repellent performance far exceeds that of traditional surfactants or single dispersants. Hydrogenated castor oil and fluorine-containing silane complement each other and synergistically enhance each other, the former builds a network structure in the bulk phase, blocking the penetration and residue of the slurry, and the latter forms a slurry-repellent layer at the particle interface, actively repelling the adhesion of the slurry. The combination of the two makes the excess slurry on the surface of the green body quickly slide off under the action of gravity or very light cleaning after printing, thereby obtaining a high-precision green body with clear details and clean surface.

[0048] At the same time, the thixotropic network of hydrogenated castor oil can effectively lock the metal powder, making it difficult to settle even in long-term static state, and the slurry has a long storage life. When used, it only needs to be simply stirred to restore its original state, avoiding printing failure caused by uneven settlement, and significantly improving material utilization. Under the action of shear thinning, the slurry can quickly flow flat during each layer printing, forming a flat and uniform thin layer, ensuring uniform solidification quality of each layer and effectively eliminating interlayer defects.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited thereto; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that; it can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A photocurable precious metal paste that resists surface coating on green bodies, characterized in that: The precious metal slurry, by mass ratio, includes 70%–89% precious metal powder, 3%–18% reactive diluent, 2%–10% oligomer, 0.5%–1.5% photoinitiator, 1%–4% dispersant, and 0.8%–2.5% anti-slurry-draping functional additives.

2. The photocurable precious metal paste for resisting surface coating of green preforms according to claim 1, characterized in that: The precious metal powder is selected from one of gold, silver, platinum, palladium, rhodium, iridium, and osmium.

3. The photocurable precious metal paste for resisting surface coating of green bodies according to claim 1, characterized in that: The reactive diluent is selected from one or more combinations of caprolactone acrylate, lauryl acrylate, 1,6-hexanediol diacrylate, dipropylene glycol diacrylate, tricyclodecanediethanol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, and dipentaerythritol hexaacrylate.

4. The photocurable precious metal paste for resisting surface coating of green bodies according to claim 1, characterized in that: The oligomer is selected from one or more combinations of epoxy acrylate, polyurethane acrylate, polyester acrylate, acrylated acrylate, and bisphenol A epoxy acrylate.

5. The photocurable precious metal paste for resisting surface coating of green preforms according to claim 1, characterized in that: The dispersant is selected from one or more combinations of BYK-110, BYK-111, BYK-163, BYK-168, BYK-LPN 21116, BYK-LPN 21117, Solsperse32000, and Solsperse39000.

6. The photocurable precious metal paste for resisting surface coating of green preforms according to claim 1, characterized in that: The photoinitiator is selected from one or more combinations of benzoin methyl ether, benzophenone, 2-isopropylthioxanthone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

7. The photocurable precious metal paste for resisting surface coating of green bodies according to claim 1, characterized in that: The anti-slurry-laden functional additive is composed of hydrogenated castor oil and fluorinated silane, wherein the fluorinated silane is 1H,1H,2H,2H-perfluorooctyltriethoxysilane, and the mass ratio of hydrogenated castor oil to fluorinated silane is 1:0.06-0.

3.

8. A method for preparing photocurable precious metal green bodies with anti-slurry coating on the surface, characterized in that, Using the photocurable precious metal paste for resisting surface coating as described in claim 1 includes the following steps: S1. Dissolve the photoinitiator in the reactive diluent according to the mass percentage, sonicate until completely dissolved, then add the oligomer and stir evenly to form a photosensitive premix; S2. Add the dispersant to the photosensitive premixed liquid according to the mass percentage and mix. After thorough mixing, add the anti-slurry additive and continue stirring until completely dissolved to form a mixture. S3. Transfer the mixture to a homogenizing tank, add precious metal powder to the homogenizing tank according to the mass percentage, start the homogenizer to mix, and obtain a photocurable precious metal slurry after mixing is completed; S4. Load the prepared photocurable precious metal paste into the printer hopper and set the printer parameters; S5. After setting the printer parameters, start the printing program. After printing, you will get a photocured precious metal blank. S6. Take out the photocurable precious metal blank and immerse it in the cleaning solution to remove the residual slurry on the surface. After the residual slurry is removed, the photocurable precious metal blank is obtained.

9. The method for preparing photocurable precious metal green bodies with surface coating according to claim 8, characterized in that: In step S4, the printer parameters adopt "high energy short time" exposure, with ultraviolet light energy of 120mJ / cm² to 160mJ / cm² and exposure time of 3s to 6s, so that the surface slurry is instantly and completely solidified to form a dense isolation layer.

10. The method for preparing photocurable precious metal green bodies with surface coating according to claim 8, characterized in that: In step S6, the cleaning solution is selected from alcohol and anhydrous ethanol.

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