Micro-jet continuous preparation method of silver neodecanoate

Abstract

The invention specifically discloses a micro-jet continuous preparation method of silver neodecanoate, aims to realize continuous and uniform preparation of silver neodecanoate by utilizing a micro-jet mixed reaction mode, and solves the problem of product agglomeration caused by non-uniform mixing possibly existing in a traditional stirring and mixing reaction. The method comprises the following steps: preparing a sodium neodecanoate solution and a silver nitrate solution, and filtering; through the microjet mixing reactor, the two solutions are subjected to high-speed jet collision at a certain point outside the mixer to realize rapid and uniform mixing and reaction; the mixed solution flows into an open type bulk phase reaction container, and nucleation and growth are completed under the conditions of temperature control and stirring; and finally, separating, washing and drying in vacuum to obtain a silver neodecanoate product. By adopting the technical scheme, instant uniform mixing of reactants and continuous preparation of products can be realized, and the uniformity and batch consistency of the products are remarkably improved.

Description

TECHNICAL FIELD The application belongs to the technical field of metal organic silver salt preparation, and particularly relates to a micro-jet continuous preparation method of silver neodecanoate. BACKGROUND Metal organic silver salt is an important functional compound, which has deep application in the fields of antibacterial, catalysis, conductive ink and advanced coating, and typical representatives include silver stearate, silver laurate, silver benzoate, silver neodecanoate and the like, which are usually prepared by liquid phase precipitation reaction. In the application field of conductive functional materials, such metal organic silver salt usually has higher sintering activity and lower sintering temperature than nano or micro silver powder, and is mainly applied to low-temperature sintering silver paste or particle-free conductive silver paste.

[0001] Silver neodecanoate is a metal organic silver salt with a relatively low decomposition temperature (about 170-175℃), which is easily dissolved in solvents such as alcohols, and can be used as a silver precursor to prepare particle-free conductive silver paste, or can be mixed with particle silver powder to prepare composite silver paste, thereby improving the low-temperature sintering characteristics of the particle silver paste.

[0002] A conductive silver paste for low-temperature co-fired ceramic substrate and a preparation method thereof are disclosed in Chinese Patent No. CN 119008076 A. The silver paste uses a composite silver powder composed of nano silver powder and silver resinate mainly of silver neodecanoate as a conductive filler. The introduction of silver resinate can effectively reduce the performance decline caused by the difference in affinity between silver powder and the substrate during sintering, and finally a conductive silver paste with good hardness, adhesion and conductivity is prepared. Chinese Patent No. CN113527937A discloses a water-based organic nanometer ink for organic thin film devices and a preparation method thereof. The nanometer ink uses silver neodecanoate as a precursor to prepare silver porous nano-SiO2 by hydrothermal reaction, which improves the ultraviolet light absorption capacity of the ink and solves the problem of nano silver ion particle agglomeration. Chinese Patent No. CN 112712913A discloses an oxidized silver paste for electronic components and a preparation method thereof. The paste is composed of oxidized silver powder, silver neodecanoate powder and solvent, which can effectively reduce the sintering temperature and has high electrical conductivity. Chinese Patent No. CN110449188 A discloses a citric acid silver / silver composite nanomaterial, a preparation method and application thereof. Silver citrate is generated from silver nitrate and sodium citrate at room temperature, and silver nanoparticles are generated by one-pot method at high temperature by controlling the reaction temperature. Invention patent No. CN106574135A discloses a particle-free molecular ink using silver neodecanoate as a silver-containing precursor. The conductive track formed by the molecular ink is thin, and has the advantages of low resistivity, low roughness and high adhesion.

[0003] The preparation of silver neodecanoate usually adopts liquid-phase chemical precipitation method. First, neodecanoic acid is reacted with sodium hydroxide solution to generate sodium neodecanoate solution, and then ion exchange reaction is continued with silver nitrate solution to generate silver neodecanoate precipitate. The precipitation reaction process occurs rapidly, and white or off-white silver neodecanoate precipitate is generated at the initial stage of solution mixing, and the product performance is highly dependent on the controllability and uniformity of nucleation and growth during the reaction process. The conventional mixing reaction process is usually carried out in a beaker or a reaction kettle, and silver nitrate solution is slowly added or dropped into sodium neodecanoate solution under stirring. The process is slow, and it is difficult to ensure that the two solutions can be mixed uniformly when they are in contact. Some unreacted sodium neodecanoate may be wrapped in the product, resulting in uneven particles, which will adversely affect the preparation, printing and use of conductive ink.

[0004] To obtain more uniform silver neodecanoate particles, the ideal continuous preparation strategy should realize the process decoupling of "instant mixing-quick removal-bulk phase reaction". The reaction solution should be mixed uniformly and precipitated rapidly when it is in contact, so as to avoid incomplete reaction of part of the organic acid or silver salt due to uneven mixing. Therefore, it is very important to control the rapid and effective solution mixing process. SUMMARY The purpose of the present application is to provide a micro-jet continuous preparation method of silver neodecanoate. By utilizing the high shear and high turbulence characteristics of micro-jet mixing reaction technology, the reaction solution is mixed by high-speed jet impact at a certain angle at a certain point outside the microchannel. This can significantly improve the uniformity of the mixing reaction of the reaction solution, effectively avoid the risk of blockage caused by solid particle deposition in the channel during mixing in the traditional microreactor, and realize the continuous production of silver neodecanoate products with high stability and high uniformity.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: A micro-jet continuous preparation method of silver neodecanoate, comprising the following specific steps: Step 1: configure the reactant solution, dissolve neodecanoic acid in deionized water containing 10% methanol or ethanol, and stir at room temperature to obtain a neodecanoic acid solution. Dissolve sodium hydroxide in deionized water to obtain a sodium hydroxide solution. Slowly add the prepared sodium hydroxide solution into the neodecanoic acid solution within 1 min, and continuously stir and mix uniformly during the process to obtain a sodium neodecanoate solution A. Dissolve silver nitrate in deionized water to obtain a silver nitrate solution B; Step 2: establish a micro-jet mixing reaction system, such as Figure 1As shown, the system includes two micro-piston pumps, two independent liquid inlet pipelines, a Y-shaped micro-fluidic mixing device, and a bulk phase reaction container. The Y-shaped micro-fluidic mixing device has two inlets, two internal micro-channels, and two outlets arranged at an angle in the same plane to ensure that the reaction liquid ejected from the two outlets intersects at a specific point outside the micro-channel outlet, ensuring that the mixing process occurs entirely in open space, avoiding the deposition of solid products inside the microstructure causing blockage. Step 3: Precise control of solution flow, accurately measure the flow of silver nitrate solution and sodium neodecanoate solution by micro-piston pump, pump into two independent liquid inlet pipelines at a flow rate of 100 milliliters per minute to 1000 milliliters per minute, the flow rate ratio of the two pipelines is controlled at 1 to 1 to maintain the accurate matching of the stoichiometric ratio. Step 4: Implement micro-fluidic mixing reaction, two reaction solutions A and B in step 3 enter the inlet 1 and inlet 2 of the Y-shaped micro-fluidic mixing reactor through two independent liquid inlet pipelines, and the reaction solutions A and B ejected from the outlet 3 and outlet 4 with a certain angle after passing through the two internal micro-channels will converge at a point at the lower part, completing instantaneous and uniform mixing in a very short time, the mixing process is in a fully turbulent state, which can effectively eliminate local concentration gradient and inhibit heterogeneous nucleation and particle agglomeration. Step 5: Mixed solution free-falls into the bulk phase reaction zone, the mixed solution flows directly from the intersection point into an open bulk phase reaction container with a volume of 1 liter to 10 liters, which contains deionized water occupying one-half of the volume of the reaction container. The mixed solution rapidly produces white or off-white silver neodecanoate solid in the container. Since the mixing has been completed externally, the reaction container only serves the function of crystallization and precipitation, with no mixing dead angles or risk of blockage. Step 6: Control reaction conditions, the bulk phase reaction container is equipped with a jacketed temperature control system, which can maintain the reaction temperature at 10 degrees Celsius to 60 degrees Celsius, and a magnetic stirrer continuously stirs the reaction mixture at a speed of 100 revolutions per minute to 500 revolutions per minute, ensuring uniform crystal growth. Step 7: Collect and post-treat the product, after continuously stirring the reaction in the bulk phase reaction container for 1-2 minutes, the generated white or off-white silver neodecanoate solid is separated by filtration or centrifugation, washed 3-4 times with deionized water, and dried in a vacuum drying oven at 40 degrees Celsius to 60 degrees Celsius in the dark for 4-6 hours to constant weight. After crushing and sieving, high-purity silver neodecanoate products with uniform morphology are obtained.

[0006] Preferably, the concentration of silver nitrate solution A and sodium neodecanoate solution B in step 1 is preferably 0.1-1.0 mol / L, to balance the reaction rate and product dispersibility, and the temperature of solution A and solution B is maintained at 25±2℃.

[0007] Preferably, the Y-shaped microjet mixing device in step 2 is manufactured by 3D printing of polyester material, which has excellent corrosion resistance and surface smoothness. The angle between the axes of the two microchannel outlets is 15 degrees to 120 degrees, the inner diameter of the nozzle outlet is 100 micrometers to 1000 micrometers, and the intersection point is precisely set at a distance of 5 mm to 10 mm from the nozzle outlet outside the microchannel.

[0008] Preferably, in step 3, the micro-flow pump can control the flow rate accuracy to ±0.1%, and the two inlet pipes are made of polytetrafluoroethylene or fluorinated ethylene propylene, with an inner diameter of 1 mm to 3 mm and a length not exceeding 2 meters, in order to minimize flow resistance and maintain flow stability.

[0009] Preferably, the microjet mixing process in step 4 can ensure that the two jets collide and mix fully in free space, enabling the two solutions to react quickly and uniformly, and completely avoids the blockage caused by nucleation inside the microchannel. This is significantly better than traditional stirring mixing methods or conventional T-type micro mixers and static mixers, and fundamentally suppresses uneven nucleation and particle agglomeration caused by local supersaturation.

[0010] Preferably, the open bulk reaction vessel in step 5 can be a jacketed glass reactor or an enamel-lined reactor, which has an optimized baffle structure and a paddle or anchor stirring paddle to ensure that the mixture is rapidly dispersed after flowing in, avoiding excessive local supersaturation. At the same time, since the mixing is completed, there is no high-speed shear or complex flow channel in the vessel, completely eliminating the possibility of blockage.

[0011] Preferably, in step 6, the jacket temperature control system can use a water bath or oil bath medium with a temperature control accuracy of ±0.5 degrees Celsius. The stirring rate of the magnetic stirrer is dynamically adjusted according to the reaction stage: a high speed of 200–500 rpm is used in the initial nucleation stage to promote dispersion, and the speed is reduced to 100–200 rpm in the crystal growth stage to reduce shear force and facilitate the formation of a regular morphology.

[0012] Preferably, in step 7, the separation operation is performed by vacuum filtration using a Buchner funnel, the product is washed 3-4 times with deionized water, the volume ratio of washing solvent to solid is 3:1 to 5:1, and then vacuum drying is performed. The vacuum degree of the vacuum drying oven is maintained at -0.09 MPa to -0.1 MPa to ensure that there is no solvent residue in the product.

[0013] Preferably, the product performance characterization step is also included, in which the final dried product and the prepared silver paste sintered sample are observed by scanning electron microscopy (SEM) to systematically evaluate their particle morphology, uniformity and density of the sintered film, and to ensure that the product meets the stringent requirements of high-end applications such as conductive inks or catalyst supports.

[0014] Compared with the prior art, the present invention has the following outstanding advantages: (1) The microjet mixing point is innovatively set in the free space outside the microchannel, so that the reactants can complete high-speed collision mixing in an open area without physical constraints, which completely avoids the blockage problem caused by the deposition and growth of solid particles in the microchannel, and significantly improves the stability and running time of continuous production; (2) By precisely controlling the geometric parameters, flow rate and intersection angle of the microjet mixing reactor, the reaction solution is rapidly and uniformly mixed, effectively eliminating local concentration fluctuations, inhibiting heterogeneous nucleation and particle agglomeration, and obtaining high-quality silver neodecanoate products with uniform reaction and low impurity content. (3) The mixing and crystallization processes are physically separated. Mixing is completed instantaneously in an open space, while crystallization is carried out in a controllable bulk reactor. The process is highly modular, easy to scale up and integrate, and suitable for industrial continuous production. Attached image description: Figure 1 This is a schematic diagram of the process for preparing silver neodecanoate using the Y-type microjet reactor in this invention. Figure 2 This is an electron microscope image of the silver neodecanoate particles prepared in Example 1 of this invention. Figure 3 This is an electron microscope image of the silver neodecanoate particles prepared in Comparative Example 1 of this invention. Figure 4 The surface and cross-sectional electron micrographs of the silver paste prepared by neodecanoate in Example 1 of this invention after sintering are shown below. Figure 5 The surface and cross-sectional electron micrographs of the silver paste prepared by Comparative Example 1 of this invention after sintering are shown below. Detailed implementation method: To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0015] Example 1 To address the core structural problems of insufficient mixing efficiency and poor batch repeatability in the traditional in-vessel stirring and mixing process for preparing silver neodecanoate, this invention proposes to significantly improve the uniformity of reactant mixing by achieving high-speed collision mixing outside the microchannel, and effectively avoid the risk of blockage caused by solid particle deposition in the traditional microchannel mixing. This enables continuous production with high stability and high repeatability, and is applied to a microjet continuous preparation method for silver neodecanoate.

[0016] In the above-mentioned microfluidic continuous preparation method of silver neodecanoate, according to the steps described, firstly, a reactant solution is prepared. 19 mL of neodecanoic acid is added to 500 mL of deionized water (containing 50 mL of methanol), and the solution is thoroughly dissolved under a constant temperature of 25°C in a water bath by stirring. 4 g of sodium hydroxide is weighed and dissolved in 500 mL of deionized water, and the solution is thoroughly dissolved under a constant temperature of 25°C by stirring to obtain a sodium hydroxide solution. The 500 mL of the prepared sodium hydroxide solution is slowly added to the 500 mL of neodecanoic acid solution over 1 minute, with continuous stirring to ensure uniform mixing, resulting in a 0.1 mol / L sodium neodecanoate solution (solution A). 17 g of silver nitrate is weighed and dissolved in 1000 mL of deionized water to prepare a 0.1 mol / L silver nitrate solution (solution B), which is transparent and colorless. Both solutions A and B are maintained at a temperature of 25±2°C. After the solution is prepared, nitrogen pressurization or vacuum degassing is used to eliminate the interference of dissolved gases on the subsequent microjet mixing process, and to avoid cavitation effects caused by bubbles in the high-speed jet, which would affect the uniformity of mixing.

[0017] The prepared sodium neodecanoate solution (solution A) and silver nitrate solution (solution B) are used as follows: Figure 1 The Y-type microjet reaction system shown uses a micro-flow pump to control a flow rate of 100 mL per minute to inject into inlet 1 and inlet 2 of the Y-type microjet reactor. The flow ratio of the two pipelines is controlled at 1:1 to maintain precise stoichiometric matching. The angle between reactor outlet 3 and outlet 4 is 60°. Fluids A and B ejected from the two outlets converge at a point outside the microjet reactor. 200 mL of deionized water is added to a 3000 mL beaker as a base liquid. The magnetic stirring speed is controlled at 200 r / min, forming a mixed solution that falls vertically into the beaker containing the deionized water base liquid. Liquids A and B rapidly mix at the confluence point, undergoing nucleation and particle growth reactions. A white or grayish-white flocculent precipitate forms in a beaker containing the base liquid. After jet mixing, stirring is continued for 2 minutes. The resulting product is separated into solid and liquid phases using vacuum filtration. The solid product is washed 3-4 times with deionized water (pH 5-6). The solid product is then dried in a vacuum oven at 50°C in the dark for 4-6 hours until constant weight. After pulverization and sieving, high-purity, uniformly morphologically uniform silver neodecanoate is obtained. Scanning electron microscopy of the obtained product is shown below. Figure 2 As shown.

[0018] Example 2 Prepare the reactant solutions: Measure 38 mL of neodecanoic acid and add it to 500 mL of deionized water (containing 50 mL of methanol). Dissolve the neodecanoic acid solution by stirring thoroughly in a water bath at a constant temperature of 25℃. Weigh 8 g of sodium hydroxide and dissolve it in 500 mL of deionized water. Dissolve the sodium hydroxide solution by stirring thoroughly in a water bath at a constant temperature of 25℃. Slowly add the 500 mL of the prepared sodium hydroxide solution to the 500 mL of neodecanoic acid solution over 1 min, stirring continuously until homogeneous. This yields a 0.2 mol / L sodium neodecanoate solution (solution A). Weigh 34 g of silver nitrate and dissolve it in 1000 mL of deionized water to prepare a 0.2 mol / L silver nitrate solution (solution B). The solution is transparent and colorless. Both solutions A and B are maintained at 25±2℃. After the solutions are prepared, they are degassed by nitrogen pressurization or vacuum to eliminate the interference of dissolved gases on the subsequent microjets mixing process and to avoid cavitation effects caused by bubbles in the high-speed jet, which would affect the mixing homogeneity.

[0019] The prepared sodium neodecanoate solution (solution A) and silver nitrate solution (solution B) are used as follows: Figure 1 The Y-type microjet reaction system shown uses a micro-flow pump to control a flow rate of 100 mL per minute to inject into inlet 1 and inlet 2 of the Y-type microjet reactor. The flow ratio of the two pipelines is controlled at 1:1 to maintain precise stoichiometric matching. The angle between reactor outlet 3 and outlet 4 is 60°. Fluids A and B ejected from the two outlets converge at a point outside the microjet reactor. 200 mL of deionized water is added to a 3000 mL beaker as a base liquid. The magnetic stirring speed is controlled at 300 r / min, forming a mixed solution that falls vertically into the beaker containing the deionized water base liquid. Liquids A and B rapidly mix at the confluence point, undergoing nucleation and particle growth reactions. A white or grayish-white flocculent precipitate is formed in a beaker containing the bottom liquid. After the spray mixing is completed, the mixture is stirred continuously for 2 minutes. The resulting product is separated into solid and liquid phases by vacuum filtration. The solid product is washed 3-4 times with deionized water, and the pH of the wash water is measured to be 5-6. The solid product is then placed in a vacuum drying oven at 50 degrees Celsius and dried in the dark for 4-6 hours until constant weight is achieved. After pulverization and sieving, a high-purity, uniformly morphological silver neodecanoate product is obtained.

[0020] Example 3 Prepare the reactant solutions: Measure 38 mL of neodecanoic acid and add it to 500 mL of deionized water (containing 50 mL of methanol). Dissolve the neodecanoic acid solution by stirring thoroughly in a water bath at a constant temperature of 25℃. Weigh 8 g of sodium hydroxide and dissolve it in 500 mL of deionized water. Dissolve the sodium hydroxide solution by stirring thoroughly in a water bath at a constant temperature of 25℃. Slowly add the 500 mL of the prepared sodium hydroxide solution to the 500 mL of neodecanoic acid solution over 1 min, stirring continuously until homogeneous. This yields a 0.2 mol / L sodium neodecanoate solution (solution A). Weigh 34 g of silver nitrate and dissolve it in 1000 mL of deionized water to prepare a 0.2 mol / L silver nitrate solution (solution B). The solution is transparent and colorless. Both solutions A and B are maintained at 25±2℃. After the solutions are prepared, they are degassed by nitrogen pressurization or vacuum to eliminate the interference of dissolved gases on the subsequent microjets mixing process and to avoid cavitation effects caused by bubbles in the high-speed jet, which would affect the mixing homogeneity.

[0021] The prepared sodium neodecanoate solution (solution A) and silver nitrate solution (solution B) are used as follows: Figure 1 The Y-type microjet reaction system shown uses a micro-flow pump to control a flow rate of 200 mL per minute to inject into inlet 1 and inlet 2 of the Y-type microjet reactor. The flow ratio of the two pipelines is controlled at 1:1 to maintain precise stoichiometric matching. The angle between reactor outlet 3 and outlet 4 is 90°. Fluids A and B ejected from the two outlets converge at a point outside the microjet reactor. 400 mL of deionized water is added to a 3000 mL beaker as a base liquid. The magnetic stirring speed is controlled at 300 r / min, forming a mixed solution that falls vertically into the beaker containing the deionized water base liquid. Liquids A and B rapidly mix at the confluence point, undergoing nucleation and particle growth reactions. A white or grayish-white flocculent precipitate is formed in a beaker containing the bottom liquid. After the spray mixing is completed, the mixture is stirred continuously for 2 minutes. The resulting product is separated into solid and liquid phases by vacuum filtration. The solid product is washed 3-4 times with deionized water, and the pH of the wash water is measured to be 5-6. The solid product is then placed in a vacuum drying oven at 50 degrees Celsius and dried in the dark for 4-6 hours until constant weight is achieved. After pulverization and sieving, a high-purity, uniformly morphological silver neodecanoate product is obtained.

[0022] Comparative Example 1 Prepare the same reactant solution as in Example 1. Measure 19 mL of neodecanoic acid and add it to 500 mL of deionized water (containing 50 mL of methanol). Dissolve the solution thoroughly by stirring in a water bath at a constant temperature of 25°C to obtain a neodecanoic acid solution. Weigh 4 g of sodium hydroxide and dissolve it in 500 mL of deionized water. Dissolve the solution thoroughly by stirring in a water bath at a constant temperature of 25°C to obtain a sodium hydroxide solution. Slowly add the prepared 500 mL sodium hydroxide solution to the 500 mL neodecanoic acid solution over 1 minute, continuously stirring and mixing until homogeneous. This yields a 0.1 mol / L sodium neodecanoate solution (Solution A). Weigh 17 g of silver nitrate and dissolve it in 1000 mL of deionized water to prepare a 0.1 mol / L silver nitrate solution (Solution B). The solution is transparent and colorless. Both Solutions A and B are maintained at 25±2°C. After the solutions are prepared, they are degassed by nitrogen pressurization or vacuum treatment.

[0023] Silver neodecanoate was prepared using a conventional stirring and mixing reaction method. 1000 mL of sodium neodecanoate solution A was placed in a 3000 mL beaker, and the magnetic stirring speed was controlled at 200 r / min. 1000 mL of silver nitrate solution (solution B) was added uniformly to sodium neodecanoate solution A over 2 minutes. White or grayish-white flocculent crystals rapidly appeared immediately after the silver nitrate solution entered the sodium neodecanoate solution. After all the solution had been added and the reaction was complete, stirring was continued for 2 minutes. The resulting product was separated into solid and liquid phases using vacuum filtration. The solid product was washed 3-4 times with deionized water, and the pH of the wash water was measured to be 5-6. The solid product was then dried in a vacuum drying oven at 50°C in the dark for 4-6 hours until constant weight. The dried product was then pulverized and sieved to obtain the silver neodecanoate product. Scanning electron microscopy of the obtained product is shown below. Figure 3 As shown.

[0024] Silver neodecanoate paste test The silver neodecanoate particles prepared in Example 1 and Comparative Example 1 were mixed with the same organic carrier in a certain proportion to prepare silver neodecanoate paste. The organic carrier consisted of butylcarbohydrate (solvent, 50 wt.%), ethyl cellulose (binder, 35 wt.%), tributyl phosphate (thixotropic agent, 8 wt.%), and dibutyl phthalate (diluent, 7 wt.%). First, the binder ethyl cellulose was dissolved in a water bath at 60°C, and then the thixotropic agent and diluent were added sequentially, followed by stirring to obtain the organic carrier. Silver neodecanoate 1# prepared in Example 1 and silver neodecanoate 2# prepared in Comparative Example 1 were added to the above organic carrier in the same proportion, with silver neodecanoate accounting for 60% by weight and the organic carrier accounting for 40%. The mixture was stirred in a high-speed mixer for 60 minutes, and then passed through a three-roll mill six times to obtain a uniformly dissolved and mixed silver neodecanoate paste.

[0025] Silver pastes of neodecanoate particles #1 and #2 were prepared in the same proportion. The fineness of the pastes was tested using a scraper fineness meter. The fineness of paste #1 was <5μm, and that of paste #2 was <9μm. This result indicates that paste #1 dissolves more uniformly in the organic carrier, and the number of non-uniform particles generated during synthesis is significantly less than that of paste #2. The silver pastes prepared from silver pastes #1 and #2 were screen-printed onto a ceramic substrate to form printed lines of a specific size, followed by curing and sintering tests. To fully verify the influence of particle uniformity on the density of the sintered silver paste film, the printed silver paste lines on the ceramic substrate were heated to 800℃ and sintered for 15 min. The surface and cross-sectional characteristics of the sintered film were observed using a scanning electron microscope. The results are as follows: Figure 4 and Figure 5 As shown. From Figure 4 and Figure 5 The surface and cross-sectional features of the sintered films shown indicate that, under the same magnification electron microscope field of view, both silver pastes exhibit some black spots and some circular or elliptical depressions on their sintered film surfaces. However, the sintered film surface of the No. 2 neodecanoic acid silver paste obtained by the conventional stirring and mixing reaction method shows more black spots, larger areas, and more pronounced uneven protrusions or depressions. Observing the cross-sections of the two sintered films, the No. 1 neodecanoic acid silver paste obtained by the microfluidic mixing reaction method used in this invention forms a smooth and continuous silver film after sintering, while the silver film formed by the No. 2 silver paste shows some breaks. Analysis suggests that the conventional stirring reaction method during the preparation of neodecanoic acid may not be able to quickly and evenly mix the reactants, resulting in some unreacted reactants or large neodecanoic acid particles that are not completely dissolved in the organic carrier. These particles are unevenly distributed in the paste during printing, resulting in a larger number of black spots after sintering, reducing the density of the sintered film and adversely affecting the application performance of the neodecanoic acid silver.

[0026] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A microfluidic continuous process for the preparation of silver neodecanoate, characterized by: The method comprises the following specific steps: Step 1: prepare silver nitrate solution A and sodium neodecanoate solution B with a certain concentration, and maintain the temperature of solution A and solution B at 25±2℃; Step 2: establish a microfluidic mixing system, which comprises two independent liquid inlet pipelines, a Y-shaped microfluidic mixing device and an open bulk phase reaction container, wherein the intersection point of the two outlets of the Y-shaped microfluidic mixing device is accurately set at a specific point outside the microchannel nozzle outlet; Step 3: implement microfluidic mixing, accurately measure the silver nitrate solution and the sodium neodecanoate solution respectively through the two independent liquid inlet pipelines into the inlets 1 and 2 of the Y-shaped microfluidic mixing reactor by the micro-pitot pump, and the reaction solutions A and B sprayed out from the outlets 3 and 4 with a certain angle after passing through the two internal microchannels will converge at a point at the lower part, and the rapid and uniform mixing is completed in a very short time, and the flow ratio of the two pipelines is controlled at 1:1; Step 4: the mixed solution freely falls into an open bulk phase reaction container containing deionized water, and the mixed solution rapidly generates white or off-white silver neodecanoate solid in the container; Step 5: after the mixed solution continuously stirs in the bulk phase reaction container for 1-2 minutes, the silver neodecanoate solid is separated by vacuum filtration, and the silver neodecanoate product is obtained after being washed by deionized water and vacuum dried in the dark for 4-6 hours.

2. The method of claim 1, wherein: The concentration of the silver nitrate solution A and the sodium neodecanoate solution B is 0.1-1.0 mol / L.

3. The method of claim 1, wherein: The Y-shaped microfluidic mixing device in step 2 is made of polyester material by 3D printing, the intersection angle of the axes of the two microchannel outlets is 15-120 degrees, the inner diameter of the nozzle outlet is 100-1000 microns, and the intersection point is accurately set at a point outside the microchannel at a distance of 5-10 mm from the nozzle outlet.

4. The method of claim 1, wherein: The micro-pitot pump in step 3 can control the flow accuracy to be ±0.1%, the inner diameter of the two liquid inlet pipelines is 1-3 mm, and the length is not more than 2 m, so as to minimize the flow resistance and maintain the flow stability.

5. The method of claim 1, wherein: The open bulk phase reaction container in step 4 is a jacketed glass reaction kettle or a enamel reaction kettle.

6. The method of claim 1, wherein: After the mixed solution continuously stirs in the bulk phase reaction container for 1-2 minutes, the silver neodecanoate solid is separated by vacuum filtration, and the silver neodecanoate product is obtained after being washed by deionized water and vacuum dried in the dark for 4-6 hours.

7. The method of claim 1, wherein: The method is suitable for continuous production, a plurality of Y-shaped microfluidic mixers can be connected in parallel to form a mixing array, which not only avoids the problem of blockage caused by the deposition and growth of solid particles in the microchannel, but also significantly improves the stability and operation time of continuous production, has high process modularization degree, is easy to scale up and integrate, and is suitable for industrial continuous production.

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