A method for preparing oil-soluble nano-silver

Abstract

This invention provides a method for preparing oil-soluble silver nanoparticles, comprising the following steps: S1100 preparation of organic silver salts, S1200 preparation of silver amine complex precursors, S1300 mixing and preheating, and S1400 synthesis of silver nanoparticles. The oil-soluble silver nanoparticles provided by this invention are a silver nanoparticle product dispersed in a non-polar organic solvent, exhibiting long-term stability and no stratification. They can be directly added to a non-polar organic system for uniform mixing, making it convenient and efficient to use.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials, specifically a method for preparing oil-soluble nanosilver. Background Technology

[0002] Currently, existing nano-silver products on the market mainly come in three types: powder, aqueous dispersion, and supported form, and are primarily used in aqueous or polar solvent systems. This presents a problem: current nano-silver products are incompatible with organic solvent systems, exhibiting issues such as precipitation, layering, aggregation, and uneven dispersion, making them difficult to use in organic polymer systems such as paints, rubber, and plastics. It's like adding salt to salad oil—it doesn't dissolve at all, but it dissolves well in water.

[0003] Therefore, there is a need for a method to prepare nano-silver products that can be uniformly dispersed in non-polar organic solvents. Summary of the Invention

[0004] To address at least one or more of the technical problems mentioned above, the present invention provides a method for preparing oil-soluble nano-silver, comprising the following steps:

[0005] Preparation steps of S1100 organic silver salt: Mix silver oxide and organic acid in a molar ratio of 1:1.1~3, add 40-50 mL of inert organic solvent, stir evenly, heat at 45-50℃ for 2-3 hours to obtain organic silver salt;

[0006] S1200 preparation steps for silver amine complex precursor: Stir the organic amine, continuously introduce nitrogen gas, add the organic silver salt to the organic amine under continuous stirring and nitrogen protection, continue stirring at room temperature or under slight heating until a transparent solution is obtained to form the silver amine complex precursor, and then continue stirring.

[0007] S1300 Mixing and Preheating: Mix a non-water-soluble organic solvent with N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat and reflux under nitrogen protection to obtain a mixed solution;

[0008] S1400 nano-silver synthesis steps: Add the silver amine complex precursor to the formed mixed solution, keep stirring and refluxing. After the reaction is completed, continue stirring and keep the reaction system under nitrogen atmosphere to cool to room temperature to obtain a primary dispersion of nano-silver.

[0009] The mixed solution in step S1300 is a solution formed by mixing a non-water-soluble organic solvent with N,N-dimethyldodecyl-propyl-3-triethoxysilane.

[0010] According to one embodiment of the present invention, in step S1100, organic acid refers to an organic compound containing a carboxylic acid group.

[0011] According to one embodiment of the present invention, in step S1100, the inert organic solvent is acetone.

[0012] According to one embodiment of the present invention, in step S1200, the molar ratio of organic amine to organic silver salt is 10:1 to 20:1.

[0013] According to one embodiment of the present invention, in step S1200, the organic amine is selected from any one of octylamine, dodecylamine, n-hexylamine, octadecylamine, and tetradecylamine.

[0014] According to one embodiment of the present invention, in step S1200, the stirring time continues for no less than 30 minutes after the formation of the silver amine complex precursor.

[0015] According to one embodiment of the present invention, in step S1300, the non-water-soluble organic solvent is selected from any one of isohexadecane, tetradecane, n-hexane, dodecane, decane, undecane, and hexadecane.

[0016] According to one embodiment of the present invention, in step S1300, the mass of the non-water-soluble organic solvent is 20.00 g, and the mass of the quaternary ammonium triethoxysilane is 0.2~0.25 g.

[0017] According to one embodiment of the present invention, step S1400 is further followed by a post-processing step S1500: the cooled primary dispersion of nano-silver is quantitatively adjusted according to the target solvent and the target concentration to obtain oil-soluble nano-silver.

[0018] According to one embodiment of the present invention, in step S1100, the organic acid is selected from any one or a mixture of several of the following: octanoic acid, n-decanoic acid, acetic acid, decanoic acid, valeric acid, propionic acid, butyric acid, nonanoic acid, and heptanoic acid.

[0019] The oil-soluble nano-silver provided by this invention is a nano-silver product dispersed in a non-polar organic solvent, exhibiting long-term stability without stratification. It can be directly added to a non-polar organic system for uniform mixing, making it convenient and efficient to use. Attached Figure Description

[0020] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding parts, wherein:

[0021] Figure 1 This is a scanning electron microscope image of the oil-soluble silver nanoparticles prepared in Example 1;

[0022] Figure 2 This is a flowchart of the preparation method of oil-soluble nano-silver provided by the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] It should be understood that the terms "comprising" and "including" as used in the specification and claims of this invention indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0025] It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in this specification and claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations.

[0026] While numerous embodiments of the invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of the invention. The appended claims are intended to define the scope of protection of the invention and therefore cover equivalents or alternatives within the scope of these claims.

[0027] Furthermore, unless otherwise specified, all raw materials used in this invention are commercially available. Any range described in this invention includes end values, any values ​​between end values, and any sub-ranges formed by end values ​​or any values ​​between end values. Unless otherwise specified, all methods and apparatuses in this invention are general methods and general apparatuses.

[0028] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0029] according to Figure 1The present invention provides a method for preparing oil-soluble nano-silver. First, an organic silver salt is prepared in step S1100; then, a silver amine complex precursor is prepared in step S1200; next, a mixing and preheating step is performed in step S1300, followed by a nano-silver synthesis step in step S1400. The complex is then injected into a high-temperature alkane solvent, where it decomposes, and the organic amine reduces Ag⁺ to silver atoms (Ag⁺). 0 Finally, the product enters the S1500 post-processing step to prepare oil-soluble nano-silver.

[0030] Specifically, the preparation method of oil-soluble nano-silver provided by the present invention includes the following steps: First, the preparation step of S1100 organic silver salt is carried out: silver oxide and organic acid are mixed in a molar ratio of 1:1.1~3, 40-50 mL of inert organic solvent is added, stirred evenly, heated at 45-50℃, and heated continuously for 2-3 hours to obtain organic silver salt.

[0031] Optionally, silver oxide and organic acid are mixed in a molar ratio of 1:2.

[0032] Silver oxide reacts with an organic acid to produce an organosilver salt and water. This is an acid-base neutralization reaction. In step S1100, the organic acid refers to an organic compound containing a carboxylic acid group. The organic acid is selected from any one of octanoic acid, n-decanoic acid, acetic acid, decanoic acid, valeric acid, propionic acid, butyric acid, nonanoic acid, and heptanoic acid. Taking octanoic acid as an example, the reaction formula is as follows: Ag₂O + 2C₇H₂O 15 COOH → 2C7H 15 COOAg + H2O.

[0033] The process then proceeds to the S1200 step for preparing the silver amine complex precursor: The organic amine is stirred, and nitrogen gas is continuously introduced. Under continuous stirring and nitrogen protection, the organic silver salt is added to the organic amine. Stirring continues at room temperature or under slight heating until a transparent solution is obtained, forming the silver amine complex precursor. Stirring continues thereafter. Room temperature or slight heating conditions refer to 25-80°C. Room temperature refers to 25°C. Slight heating conditions refer to temperatures greater than 25°C and less than 80°C. Preferably, the temperatures are 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, and 80°C. Those skilled in the art can select appropriate temperature conditions based on specific experimental conditions.

[0034] Preferably, in step S1200, the molar ratio of the organic amine to the organic silver salt is 10:1 to 20:1. Optionally, the molar ratio of the organic amine to the organic silver salt is 11:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, or 20:1.

[0035] Preferably, in step S1200, the organic amine is selected from any one of octylamine, dodecylamine, n-hexylamine, octadecylamine, and tetradecylamine.

[0036] Preferably, in step S1200, the stirring time continues for no less than 30 minutes after the formation of the silver amine complex precursor.

[0037] Next, proceed to the S1300 mixing and preheating steps: Mix the non-water-soluble organic solvent and quaternary ammonium triethoxysilane, and heat and reflux under nitrogen protection to obtain a mixed solution.

[0038] Preferably, the heating temperature in S1300 is 130℃~180℃. Optionally, those skilled in the art can select heating temperatures of 130℃, 140℃, 150℃, 170℃, or 180℃ according to specific experimental conditions. Preferably, at room temperature, excess organic amine reacts with silver organic acid to form a colorless silver amine complex. If the selected organic amine has too high a viscosity or is a solid, a suitable inert solvent needs to be selected.

[0039] Preferably, in step S1300, the non-water-soluble organic solvent is selected from any one of isohexadecane, tetradecane, n-hexane, dodecane, decane, undecane, and hexadecane.

[0040] Preferably, in step S1300, the quaternary ammonium triethoxysilane is N,N-dimethyldodecyl-propyl-3-triethoxysilane.

[0041] N,N-Dimethyldodecylpropyl-3-triethoxysilane molecular weight: 454.21.

[0042] Preferably, in step S1300, the mass of the non-water-soluble organic solvent is 20.00 g, and the mass of N,N-dimethyldodecyl-propyl-3-triethoxysilane is 0.2~0.25 g, i.e. 0.00044 mol~0.00055 mol.

[0043] Then proceed to the S1400 nano-silver synthesis step: add the silver amine complex precursor to a mixed solution formed by a non-water-soluble organic solvent and N,N-dimethyldodecyl-propyl-3-triethoxysilane, keep stirring and reflux, and after the reaction is completed, continue stirring and keep the reaction system under nitrogen atmosphere to cool to room temperature to obtain a primary dispersion of nano-silver.

[0044] Preferably, the heating temperature in the S1400 nano-silver synthesis step is 150-180℃.

[0045] In the synthesis of S1400 nanosilver, N,N-dimethyldodecyl-propyl-3-triethoxysilane (i.e., dodecyl quaternary ammonium triethoxysilane), organic amines, and organic acids are used as mixed ligands, which adsorb onto the surface of the nanosilver, providing steric hindrance and achieving natural and stable dispersion. Specifically, N,N-dimethyldodecyl-propyl-3-triethoxysilane (dodecyl quaternary ammonium triethoxysilane) undergoes high-temperature de-alcoholization condensation to form an anchored stable ligand on the nanosilver surface. Octylamine and octanoic acid form unstable ligands.

[0046] Preferably, in step S1400: after the reaction is completed, the stirring time is continued for at least 30 minutes.

[0047] Preferably, the S1400 nanosilver synthesis step involves a reflux reaction time of at least 60 minutes.

[0048] Preferably, the volume ratio of the silver amine complex, the alkane solvent, and the N,N-dimethyldodecyl-propyl-3-triethoxysilane mixed solution is 1:1.2~1.5.

[0049] Preferably, the mass ratio of the silver amine complex to the mixed solution formed by the non-water-soluble organic solvent and N,N-dimethyldodecyl-propyl-3-triethoxysilane is 1:0.1~0.3.

[0050] In the synthesis of S1400 nano-silver, when the ratio of silane to silver amine complex is greater than 0.1:1, quaternary ammonium triethoxysilane can achieve sufficient coating. The excess will be separated out later, or a small amount will remain in the solution.

[0051] Preferably, the ratio of silver oxide (Ag2O):dodecyl quaternary ammonium triethoxysilane is 1:0.1~0.3 (mass ratio).

[0052] Preferably, the S1400 nano-silver synthesis step yields a primary dispersion of nano-silver with a nano-silver content of approximately 3.3% (i.e., 33,000 ppm). The next step is to precisely adjust the concentration to meet the requirements.

[0053] Finally, the S1500 post-processing step involves quantitatively adjusting the cooled primary dispersion of nano-silver according to the target solvent and target concentration to obtain oil-soluble nano-silver.

[0054] Preferably, in the S1500 post-treatment step, the concentration of the primary nano-silver dispersion is approximately 3.3% (i.e., 33,000 ppm), the target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. The operation method is as follows: accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix them, and stir thoroughly to obtain the 0.33% target product.

[0055] Preferably, in the S1500 post-processing step, the concentration of the primary nano-silver dispersion is approximately 3.3% (i.e., 33,000 ppm), the target product concentration is 6.6% (mass ratio), and the target solvent is isohexadecane. The operation method is as follows: accurately weigh 100 grams of the primary nano-silver dispersion, distill under reduced pressure, and concentrate to 50 grams to obtain the target product with a concentration of 6.6%.

[0056] The target solvent for the silver nanoparticles prepared by the method of this invention is a non-polar organic solvent. The target solvent is selected from one or more of benzene compounds, alkanes, cycloalkanes, and organosilicon solvents. The target solvent can be user-specified to ensure consistency with the original formulation system. For example, toluene and xylene are commonly used as thinners for paints, so the specified solvent can be selected according to user needs. For organosilicon polymers, octamethylcyclotetrasiloxane is commonly used as a thinner, so octamethylcyclotetrasiloxane can also be used to maintain consistency. Since solvents are not required in the plastic production process, solvents with good compatibility and low volatility, such as isohexadecane, can be selected to match the plastic and prevent bubbles during molding.

[0057] The target concentration refers to the concentration preset at the beginning of production, whether it is 5000ppm, 25000ppm or other values.

[0058] S1500 Post-processing Steps: Concentration Adjustment: After cooling, precisely adjust the concentration of the primary dispersion according to the required solvent and concentration. Store in a light-proof, sealed container.

[0059] Characterization and performance testing of oil-soluble silver nanoparticles: 1. Silver content can be determined using a thermogravimetric analyzer (TGA). 2. Dispersion stability can be evaluated through a static settling experiment. 3. Nanoparticle characteristics: The morphology of nanoparticles can be observed using a scanning electron microscope, and the nanoparticle size can also be measured using a laser particle size analyzer.

[0060] Example 1

[0061] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of octanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver octanoate to 0.15 mol of octylamine, and continue stirring at 35°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of isohexadecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes. Cool the reaction system to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix thoroughly, and obtain the 0.33% target product.

[0062] Example 2

[0063] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of octanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver octanoate to 0.15 mol of octylamine, and continue stirring at 35°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of tetradecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of tetradecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is tetradecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of tetradecane, mix thoroughly, and obtain the 0.33% target product.

[0064] Example 3

[0065] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of decanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver decanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver decanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver decanoate to 0.15 mol of octylamine, and continue stirring at 35°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of isohexadecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix thoroughly, and obtain the 0.33% target product.

[0066] Example 4

[0067] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of acetic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver acetate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver acetate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir dodecylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver acetate to 0.15 mol of dodecylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of n-hexane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of n-hexane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is n-hexane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of n-hexane, mix thoroughly, and obtain the 0.33% target product.

[0068] Example 5

[0069] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of decanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver decanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver decanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir n-hexylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver decanoate to 0.15 mol of n-hexylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then, proceed to the S1300 mixing and preheating step: Mix 20 g of isododecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isododecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isododecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isododecane, mix thoroughly, and obtain the 0.33% target product.

[0070] Example 6

[0071] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of valeric acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver valeric acid suspension. Filter the suspension and wash with acetone, then vacuum dry the silver valeric acid filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octadecylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver valeric acid to 0.15 mol of octadecylamine. Continue stirring at room temperature or under slight heating until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of dodecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, heat to 130°C and reflux under nitrogen protection to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of dodecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is dodecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of dodecane, mix thoroughly, and obtain the 0.33% target product.

[0072] Example 7

[0073] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of propionic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver propionate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver propionate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver propionate to 0.15 mol of octylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then, proceed to the S1300 mixing and preheating step: Mix 20 g of decane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of decane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is decane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of decane, mix thoroughly, and obtain the 0.33% target product.

[0074] Example 8

[0075] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of butyric acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver butyrate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver butyrate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir dodecylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver butyrate to 0.15 mol of dodecylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of decane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of decane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is decane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of decane, mix thoroughly, and obtain the 0.33% target product.

[0076] Example 9

[0077] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of nonanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver nonanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver nonanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir dodecylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver nonanoate to 0.15 mol of dodecylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then, proceed to the S1300 mixing and preheating step: Mix 20 g of undecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of undecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is undecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of undecane, mix thoroughly, and obtain the 0.33% target product.

[0078] Example 10

[0079] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of heptanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver heptanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver heptanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir tetradecylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver heptanoate to 0.15 mol of tetradecylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of hexadecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of hexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is hexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of hexadecane, mix thoroughly, and obtain the 0.33% target product.

[0080] The parameters for Examples 1-10 are shown in Table 1.

[0081] Table 1. Parameters of Examples 1-10

[0082]

[0083] Example 11

[0084] First, proceed to the preparation step of the S1100 organic silver salt: Mix 0.01 mol silver oxide and 0.03 mol octanoic acid, add 40 mL acetone, stir evenly, and heat at 45°C for 2 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the preparation step of the S1200 silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol silver octanoate to 0.20 mol octylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Next, proceed to the S1300 mixing and preheating step: Mix 20g of isohexadecane and 0.25g (0.00055mol) of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection, then reflux to obtain a mixed solution. Then proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to the mixed solution formed by isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane, and react at 150°C under stirring and reflux for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary dispersion of nano-silver. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of primary dispersion of nano-silver and 90 grams of isohexadecane, mix them thoroughly, and obtain the target product of 0.33%.

[0085] Example 12

[0086] First, proceed to the preparation step of the S1100 organic silver salt: Mix 0.01 mol silver oxide and 0.011 mol octanoic acid, add 40 mL acetone, stir evenly, and heat at 45°C for 2 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the preparation step of the S1200 silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol silver octanoate to 0.10 mol octylamine, and continue stirring at 35°C until a transparent solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. The process then proceeds to the S1300 mixing and preheating step: 20 g of isohexadecane and 0.2 g (0.00044 mol) of N,N-dimethyldodecyl-propyl-3-triethoxysilane are mixed and heated to 130°C under nitrogen protection and refluxed to obtain a mixed solution. Next, the S1400 nano-silver synthesis step is performed: the silver amine complex precursor is added to the mixed solution formed by isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. The mixture is stirred and refluxed at 150°C for 60 minutes. After the reaction, stirring continues for 30 minutes, and the reaction system is cooled to room temperature under a nitrogen atmosphere to obtain a primary dispersion of nano-silver. The nano-silver content is approximately 3.3% (33,000 ppm). Finally, the S1500 post-processing step is performed: the target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of primary dispersion of nano-silver and 90 grams of isohexadecane, mix them thoroughly, and obtain the target product of 0.33%.

[0087] Example 13

[0088] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of octanoic acid, add 45 mL of acetone, stir until homogeneous, and heat at 48°C for 2.5 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver octanoate to 0.15 mol of octylamine, and continue stirring at 50°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then, proceed to the S1300 mixing and preheating step: Mix 20 g of isohexadecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 180°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 180°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes. Cool the reaction system to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix thoroughly, and obtain the 0.33% target product.

[0089] Example 14

[0090] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.02 mol of octanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 50°C for 3 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver octanoate to 0.15 mol of octylamine, and continue stirring at 80°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of isohexadecane and 0.0005 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 180°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 180°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes. Cool the reaction system to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix thoroughly, and obtain the 0.33% target product.

[0091] Example 15

[0092] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.03 mol of octanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 45°C for 2 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver octanoate to 0.20 mol of octylamine, and continue stirring at 25°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then proceed to the S1300 mixing and preheating step: Mix 20 g of isohexadecane and 0.00055 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 130°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 150°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes. Cool the reaction system to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix thoroughly, and obtain the 0.33% target product.

[0093] Example 16

[0094] First, proceed to the S1100 step for preparing the organic silver salt: Mix 0.01 mol of silver oxide and 0.03 mol of octanoic acid, add 40 mL of acetone, stir until homogeneous, and heat at 50°C for 3 hours to obtain a silver octanoate suspension. Filter the suspension and wash with acetone, then vacuum dry the silver octanoate filter cake for later use. Next, proceed to the S1200 step for preparing the silver amine complex precursor: Stir octylamine and continuously purge with nitrogen. Under continuous stirring and nitrogen protection, add 0.01 mol of silver octanoate to 0.20 mol of octylamine, and continue stirring at 80°C until a clear solution is obtained, forming the silver amine complex precursor. Continue stirring for 30 minutes. Then, proceed to the S1300 mixing and preheating step: Mix 20 g of isohexadecane and 0.00055 mol of N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat to 180°C under nitrogen protection and reflux to obtain a mixed solution. Then, proceed to the S1400 nano-silver synthesis step: Add the silver amine complex precursor to a mixed solution of isohexadecane and N,N-dimethyldodecyl-propyl-3-triethoxysilane. Recycle at 180°C with stirring for 60 minutes. After the reaction, continue stirring for 30 minutes, and allow the reaction system to cool to room temperature under a nitrogen atmosphere to obtain a primary nano-silver dispersion. The nano-silver content is approximately 3.3% (i.e., 33,000 ppm). Finally, proceed to the S1500 post-processing step: The target product concentration is 0.33% (mass ratio), and the target solvent is isohexadecane. Accurately weigh 10 grams of the primary nano-silver dispersion and 90 grams of isohexadecane, mix thoroughly, and obtain the 0.33% target product.

[0095] In the preparation method of oil-soluble nano-silver provided by the present invention, the method for monitoring the synthesis process of nano-silver can be ultraviolet-visible absorption spectroscopy and visual aid.

[0096] Due to the surface plasmon resonance effect, silver nanoparticles exhibit a characteristic absorption peak in the visible light region (around 400-450 nm). The position, intensity, and shape of this peak directly reflect the formation, size, shape, and aggregation state of the silver nanoparticles. During the reaction, a small sample is taken from the reaction solution using a micropipette at regular intervals (e.g., every 5 minutes) for dilution with the production solvent before detection.

[0097] Reaction start: No characteristic peaks; Reaction progress: Absorption peaks appear and gradually increase in the vicinity of ~400-450 nm, indicating that silver nanoparticles begin nucleation and growth; Reaction endpoint: The intensity and position of the absorption peaks no longer change with time, indicating that the reaction is basically complete. Peak shape analysis: The narrower the peak, the more uniform the size distribution; a blue shift (movement to shorter wavelengths) usually means smaller particles, while a red shift (movement to longer wavelengths) may mean larger particles or aggregation.

[0098] The preparation process of silver nanoparticles can also be monitored visually: changes in solution color are a very simple and effective preliminary indicator. Ag⁺ ion solutions are colorless. As silver nanoparticles are formed, the solution gradually changes from pale yellow to dark yellow to brown, and may even show other colors (depending on the shape and size of the particles). If the solution shows obvious graying or precipitation, it may mean that the silver nanoparticles have undergone severe aggregation.

[0099] The oil-soluble nano-silver provided by this invention is a nano-silver product dispersed in a non-polar organic solvent, exhibiting long-term stability without stratification. It can be directly added to a non-polar organic system for uniform mixing, making it convenient and efficient to use.

[0100] The morphology of the oil-soluble silver nanoparticles prepared in Example 1 of this invention was observed using scanning electron microscopy. Figure 1 It can be seen that silver exists in the form of nanoparticles with a particle size of less than 1 micrometer.

[0101] Using the same method, scanning electron microscopy observation of the silver nanoparticles prepared by process 2-16 showed that the silver element existed in the form of nanoparticles with a particle size of less than 1 micrometer.

[0102] The oil-soluble nano-silver prepared by the method of the present invention has the following morphologies: spherical, cubic, triangular, and hexagonal.

[0103] Since organic amines are temporary protective agents, while organosilicones provide long-lasting protection, and amines and solvents are easily eluted. The oil-soluble nanosilver prepared by the method of this invention is bonded to quaternary ammonium triethoxysilane via silicon oxide bonds. Simultaneously, silane monomers form a network polymer on the surface of the nanosilver, creating stable ligands. Furthermore, quaternary ammonium triethoxysilane, as a quaternary ammonium salt compound, possesses antibacterial and disinfecting properties, enhancing the antibacterial properties of the nanosilver—a double benefit. Other types of silanes do not possess this property.

[0104] Fourier transform infrared spectroscopy (FTIR) was used to detect the presence of silane characteristic functional groups (Si-O, CH) in the silver nanoparticles prepared in Examples 1-16, proving that the silane was successfully encapsulated via chemical bonding. It is evident that the silver nanoparticles prepared according to the method of this invention contain anchored stable ligands.

[0105] The antibacterial durability of the nanosilver prepared in Examples 1-16 was tested.

[0106] The testing standard is GB / T 21866-2008.

[0107] Test method: 1. After spraying and wiping with Silver Guard M nano-silver ion disinfectant, a nano-silver ion antibacterial layer is formed on the surface of the hard ceramic; 2. The surface of the hard ceramic is rinsed with pure water for 1 minute every 30 minutes and then dried. After 24 cycles, the antibacterial performance of the hard surface (Staphylococcus aureus, Escherichia coli) is tested. The test results are shown in Table 2.

[0108] Table 2

[0109]

[0110]

[0111]

[0112] As shown in Table 1, the nano-silver prepared in Examples 1-16, after being rinsed every 30 minutes for 24 cycles, all exhibited a surface antibacterial rate greater than 99% and an antibacterial grade of Class I, making them suitable for locations requiring high antibacterial performance. This demonstrates that the nano-silver prepared by the method of this invention possesses a long-lasting antibacterial effect.

[0113] The method for preparing oil-soluble nano-silver provided by this invention uses general-purpose equipment such as a reaction vessel, and the reflux device is also general-purpose equipment. Preferably, the reaction apparatus used in the method provided by this invention is the LDG-200 conical ribbon internal heating vacuum reaction vessel from Changzhou Suzhou Bao Drying Equipment Co., Ltd. It consists of an interconnected ribbon drying main unit, condenser, vacuum tank, vacuum pump, connecting pipes and valves, and control system. The reaction apparatus is lined with polytetrafluoroethylene or enamel; glass containers can also be used, but metal containers cannot be used. The stirrer must also be enamel-lined or lined with polytetrafluoroethylene resin.

[0114] The technical solution of the present invention is further described below:

[0115] Phase 1: Preparation of Organic Silver Salts

[0116] [Reaction Principle]:

[0117] Silver oxide reacts with organic acids to produce organosilver salts and water. This is an acid-base neutralization reaction, and butyric acid, hexanoic acid, octanoic acid, and decanoic acid can be used. Taking octanoic acid as an example, the reaction equation is as follows:

[0118] Ag₂O + 2C₇H₂O 15 COOH → 2C7H 15 COOAg+H2O

[0119] 1. Operating steps:

[0120] (1) Weighing: In a well-ventilated place and under light-protected conditions, accurately weigh the following using an electronic balance:

[0121] Silver oxide (Ag₂O): 2.32 g (approximately 0.01 mol).

[0122] Organic acids: 0.011~0.03 mol, converted to parts by mass, the dosage is detailed in each example.

[0123] Ratio: Silver oxide (Ag₂O): Organic acid = 1 : 1.1~3 (mol)

[0124] (2) Feeding: Pour the weighed silver oxide and organic acid into a 100 mL dry round-bottom flask. See each example for the dosage details.

[0125] (3) Dissolving: Add about 40-50 mL of acetone to the flask.

[0126] (4) Reaction apparatus: Connect the flask to the spherical condenser, install a dryer on the upper end of the condenser, and fix the entire apparatus on the magnetic stirrer.

[0127] 3. Reaction process:

[0128] 1. Turn on the magnetic stirrer. The silver oxide powder will disperse in the solvent as the stirrer is turned on.

[0129] 2. Heat the mixture in a water bath at 50°C for 2-3 hours.

[0130] 3. During the reaction, the color of the mixture will gradually lighten, eventually forming a white or off-white organic silver salt suspension.

[0131] 4. Washing:

[0132] After the reaction is complete, allow the reaction system to cool to room temperature.

[0133] Filter the filter cake and wash it 3-5 times with an appropriate amount of acetone to remove impurities. Store the filter cake away from light.

[0134] 5. Dry and store for later use.

[0135] Place the filter cake in a light-proof vacuum desiccator and dry at room temperature for at least 18 hours, or until the product reaches constant weight and is fully dried. Store the dried organic silver salt in a sealed container away from light.

[0136] Phase 2: Preparation of Primary Dispersion of Nano Silver

[0137] [Reaction Principle]:

[0138] A stable, oil-soluble nano-silver dispersion was prepared by using a pre-synthesized silver amine complex as a precursor and then performing medium-temperature thermal decomposition (130-160℃) in an alkane solvent.

[0139] 1. Complexation: At room temperature, excess organic amine reacts with silver organic acid to form a colorless silver amine complex. If the selected organic amine has too high a viscosity or is a solid, a suitable inert solvent must be selected. See each example for dosage details.

[0140] 2. Thermal decomposition and reduction: When the complex is injected into a high-temperature alkane solvent, it decomposes, and the organic amine reduces Ag⁺ to silver atoms (Ag⁺). 0 ).

[0141] 3. Key points for stable dispersion: N,N-dimethyldodecyl-propyl-3-triethoxysilane (i.e., dodecyl quaternary ammonium triethoxysilane), organic amines, and organic acids are used as mixed ligands, adsorbed onto the surface of silver nanoparticles, providing steric hindrance and achieving naturally stable dispersion. Specifically, N,N-dimethyldodecyl-propyl-3-triethoxysilane (dodecyl quaternary ammonium triethoxysilane) undergoes de-alcoholization condensation at high temperature, forming an anchored stable ligand on the silver nanoparticle surface. Octylamine and octanoic acid form unstable ligands. See each example for dosage details.

[0142] Quaternary ammonium triethoxysilane, as a quaternary ammonium salt compound, possesses antibacterial properties, thus enhancing the antibacterial properties of nano-silver—a double benefit. Other types of silanes do not possess this property.

[0143] [Reagents]:

[0144] Organic silver, organic amine, N,N-dimethyldodecyl-propyl-3-triethoxysilane (quaternary ammonium triethoxysilane), alkane solvent, high-purity nitrogen, anhydrous ethanol, acetone;

[0145] [Instruments and Equipment]:

[0146] Erlenmeyer flask (or three-necked flask)

[0147] Mechanical stirrer or magnetic stirrer

[0148] Precision temperature-controlled oil bath

[0149] Spherical condenser tube

[0150] syringe

[0151] thermometer or thermocouple

[0152] Rotary evaporator

[0153] High-purity nitrogen cylinder

[0154]

Operating Steps

[0155] Step 1: Preparation of silver ammonia complex

[0156] 1. Preparation:

[0157] All glassware was washed and dried, and the reaction apparatus was assembled. A 100mL three-necked flask was equipped with a stirrer, a condenser, and a nitrogen inlet.

[0158] 2. Weighing and loading:

[0159] Measure out the organic amine and add it to the reaction flask. See each example for the dosage details.

[0160] Turn on the nitrogen flow (50 mL / min) and continue purging.

[0161] 3. Synthetic complexes:

[0162] Under continuous stirring and nitrogen protection, precisely weighed organic silver salts are added to the organic amine in batches and slowly.

[0163] Start stirring; the organic acid silver salt gradually dissolves, eventually forming a colorless or pale yellow transparent solution.

[0164] After the addition of the materials is complete, continue stirring for 30 minutes at room temperature or under slight heat. The resulting transparent solution is the silver amine complex precursor solution.

[0165] 4. Dosage range of organic amines:

[0166] Organic amine: Silver (Ag) ≈ 20 : 1 (molar ratio).

[0167] (The amine / silver molar ratio can be selected from 10:1 to 20:1, whichever is acceptable). See each example for dosage details.

[0168] Step 2: Preparation of Primary Dispersion of Nano Silver

[0169] 1. Experiment Start-up:

[0170] In a three-necked flask, add an alkane solvent and N,N-dimethyldodecyl-propyl-3-triethoxysilane (quaternary ammonium triethoxysilane).

[0171] Set up the experimental setup, including stirring, condensation, and nitrogen protection devices.

[0172] Under nitrogen protection, heat the alkane solvent to 130℃~180℃ in an oil bath and reflux.

[0173] 2. High-temperature reaction:

[0174] A solution of the silver amine complex was injected into a three-necked flask to initiate the reaction. The solution changed from colorless to brownish-yellow, and the color gradually deepened as nano-silver was gradually formed.

[0175] Then, the reaction was refluxed at 150-180°C with stirring. After the reaction was completed, the system was allowed to cool naturally to room temperature under continuous stirring and a nitrogen atmosphere. A primary dispersion of nano-silver was obtained, with a nano-silver content of approximately 3.3% (i.e., 33,000 ppm). The next step is to precisely adjust the concentration to meet the requirements.

[0176] Phase 3: Post-processing

[0177] [Adjusting the concentration]:

[0178] 1. After cooling, the primary dispersion is precisely quantified according to the required solvent and concentration.

[0179] 2. Store in a cool, dark place in a sealed container.

[0180] Characterization and Performance Testing

[0181] 1. The silver content can be determined using a thermogravimetric analyzer (TGA).

[0182] 2. Evaluate the dispersion stability through a static settling experiment.

[0183] 3. Nanoparticle characteristics: The morphology of nanoparticles can be observed by scanning electron microscopy, and the nanoparticle size can also be measured by laser particle size analyzer.

[0184] Methods for monitoring the synthesis process of silver nanoparticles

[0185] [Monitoring Method] Ultraviolet-Visible Absorption Spectroscopy

[0186] [Principle]: Due to the surface plasmon resonance effect, silver nanoparticles exhibit a characteristic absorption peak in the visible light region (around 400-450 nm). The position, intensity, and shape of this peak directly reflect the formation, size, shape, and aggregation state of the silver nanoparticles.

[0187]

Operating Instructions

[0188] During the reaction, a small sample is taken from the reaction solution every certain period of time (e.g., every 5 minutes) using a micropipette to dilute the sample with the production solvent before testing.

[0189] [Testing Content]:

[0190] Reaction begins: No characteristic peaks are observed.

[0191] The reaction proceeds as follows: The absorption peak that appears and gradually increases in the vicinity of ~400-450 nm indicates that the silver nanoparticles begin to nucleate and grow.

[0192] Reaction endpoint: The intensity and position of the absorption peak no longer change with time, indicating that the reaction is basically complete.

[0193] Peak shape analysis: The narrower the peak, the more uniform the size distribution; a blue shift (movement to shorter wavelengths) usually means smaller particles, while a red shift (movement to longer wavelengths) may mean larger particles or aggregation.

[0194] [Visual aids in judgment]

[0195] Changes in solution color are a very simple and effective preliminary indicator.

[0196] Ag⁺ ion solutions are colorless.

[0197] As nano-silver is formed, the solution gradually changes from pale yellow to dark yellow to brown, and may even show other colors (depending on the shape and size of the particles).

[0198] If the solution shows obvious gray color or precipitation, it may mean that the nano-silver has undergone severe aggregation.

[0199] While numerous embodiments of the invention have been shown and described herein, it will be apparent to those skilled in the art that such embodiments are provided by way of example only. Many modifications, alterations, and alternatives will occur to those skilled in the art without departing from the spirit and essence of the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in the practice of the invention. The appended claims are intended to define the scope of protection of the invention and therefore cover equivalents or alternatives within the scope of these claims.

Claims

1. A method for preparing oil-soluble silver nanoparticles, comprising the following steps: (S1100) Preparation steps of organic silver salt: Mix silver oxide and organic acid in a molar ratio of 1:1.1~3, add 40-50 mL of inert organic solvent, stir evenly, heat at 45-50℃ for 2-3 hours, and dry to obtain organic silver salt; (S1200) Preparation of silver amine complex precursor: Stir the organic amine, continuously introduce nitrogen gas, add the organic silver salt to the organic amine under continuous stirring and nitrogen protection, continue stirring until a transparent solution is obtained to form the silver amine complex precursor, and then continue stirring. (S1300) Mixing and preheating steps: Mix the non-water-soluble organic solvent with N,N-dimethyldodecyl-propyl-3-triethoxysilane, and heat and reflux under nitrogen protection to obtain a mixed solution; (S1400) Nano-silver synthesis steps: Add the silver amine complex precursor to the mixed solution, keep stirring and refluxing. After the reaction is completed, continue stirring and keep the reaction system under nitrogen atmosphere to cool to room temperature to obtain a primary dispersion of nano-silver.

2. The preparation method according to claim 1, characterized in that, In step (S1100), the organic acid refers to an organic compound containing a carboxylic acid group.

3. The preparation method according to claim 1, characterized in that, In step (S1100), the inert organic solvent is acetone.

4. The preparation method according to claim 1, characterized in that, In step (S1200), the organic amine is selected from one or more of octylamine, dodecylamine, n-hexylamine, octadecylamine, and tetradecylamine.

5. The preparation method according to claim 1, characterized in that, In step (S1200), the stirring time should continue for no less than 30 minutes after the formation of the silver amine complex precursor.

6. The preparation method according to claim 1, characterized in that, In step (S1300), the non-water-soluble organic solvent is selected from any one of isohexadecane, tetradecane, n-hexane, dodecane, decane, undecane, and hexadecane.

7. The preparation method according to any one of claims 1-6, characterized in that, (S1400) The step further includes (S1500) a post-processing step: the cooled primary dispersion of nano-silver is quantitatively adjusted according to the target solvent and target concentration to obtain oil-soluble nano-silver.

8. The preparation method according to any one of claims 1-6, characterized in that, In step (S1100), the organic acid is selected from any one or a mixture of several of the following: octanoic acid, decanoic acid, acetic acid, decanoic acid, valeric acid, propionic acid, butyric acid, nonanoic acid, and heptanoic acid.

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