Preparation method of monodisperse high-crystalline superfine copper powder

Abstract

The application belongs to the technical field of metal materials, and provides a preparation method of monodisperse high-crystalline superfine copper powder. The preparation method comprises the following steps: S1, mixing a copper-containing solution, a dispersant solution and a reducing agent solution to obtain cuprous oxide precursor by reaction; S2, mixing the cuprous oxide precursor solution, the dispersant solution and the reducing agent solution to obtain copper seeds by reaction; and S3, mixing the seeds, deoxygenated water solvent and surface modifier in a protective gas to obtain the monodisperse high-crystalline superfine copper powder by reaction. The preparation method can freely control the particle size of the superfine copper powder, and the prepared superfine copper powder is smooth in surface, uniform in size and excellent in oxidation resistance.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, and in particular to a method for preparing monodisperse, highly crystalline, ultrafine copper powder. Background Technology

[0002] Ultrafine copper powder has wide applications in civilian, industrial, and defense sectors. Since the discovery in 1995 that its low resistance could be used for electronic connections, its properties have attracted the attention of the electronics industry. As a metallic conductive phase, ultrafine copper powder exhibits high conductivity and strength, possessing excellent electrical properties, and is widely used in conductive adhesives, conductive coatings, and electrode materials. Furthermore, the micro-nano size of ultrafine copper powder results in a small-size effect, and its large specific surface area leads to a high number of surface active sites, making it an excellent catalyst in metallurgy and petrochemicals. It is widely used in the hydrogenation and dehydrogenation reactions of polymers, as well as in the production of conductive fibers from ethylene polymerization. Additionally, in automotive exhaust purification, ultrafine copper powder can be used as a catalyst to partially replace precious metals such as platinum and ruthenium, converting toxic carbon monoxide into carbon dioxide and chlorine monoxide into hydrogen peroxide. Ultrafine copper powder can also be added to automotive engine oil as a lubricant additive, reducing engine starting current and increasing cylinder pressure. It can also form a protective film on cylinder liners and piston rings, ensuring safe operation for extended periods even in the event of lubrication system failure, thus possessing significant military application value. Therefore, ultrafine copper powder, as an important industrial raw material, can replace precious metal powders in applications such as high-efficiency catalysts, conductive pastes, conductive adhesives, and high-grade lubricants. Due to its ability to significantly reduce industrial costs, its application prospects are broad.

[0003] Currently, methods for preparing ultrafine copper powder include thermal decomposition, mechanochemical methods, electron beam irradiation, sol-gel methods, and electrochemical methods. However, these existing preparation techniques often suffer from drawbacks such as complex process conditions, high energy consumption, rough surfaces with numerous spots, poor monodispersity of copper powder particles, wide size distribution range, non-uniform size, poor oxidation resistance, and poor crystallinity. Therefore, providing a low-cost, simple method for preparing ultrafine copper powder with uniform size and strong oxidation resistance has become a pressing problem for those skilled in the art. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing monodisperse, highly crystalline ultrafine copper powder. Its purpose is to solve the technical problems existing in current methods for preparing ultrafine copper powder, such as complex process conditions, high energy consumption, uneven surface with numerous spots, poor monodispersity of copper powder particles, wide size distribution range, non-uniform size, poor oxidation resistance, and poor crystallinity.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This invention provides a method for preparing monodisperse, highly crystalline, ultrafine copper powder, comprising the following steps:

[0007] S1. A copper-containing solution, a dispersant solution, and a reducing agent solution are mixed and reacted to obtain a cuprous oxide precursor.

[0008] S2. Copper seed crystals are obtained by mixing cuprous oxide precursor solution, dispersant solution and reducing agent solution and then reacting them.

[0009] S3. In a protective gas atmosphere, the seed crystals are mixed with deoxygenated water solvent and surface modifier and reacted to obtain monodisperse highly crystalline ultrafine copper powder.

[0010] The seed crystal is a copper seed crystal or a copper seed crystal with adjusted particle size.

[0011] Furthermore, the particle size of the copper seed crystals obtained in step S2 is 50nm≤D≤436nm; the particle size of the copper seed crystals after particle size adjustment is 436nm<D≤3000nm.

[0012] The preparation steps of the copper seed crystals after particle size control are as follows:

[0013] (1) Mix the cuprous oxide precursor obtained in step S1, the copper seed crystal obtained in step S2, and water to obtain a mixed solution;

[0014] (2) The mixed solution, dispersant solution and reducing agent solution are mixed and reacted to obtain large-particle copper seed crystals;

[0015] In step (1), the molar ratio of the cuprous oxide precursor obtained in step S1 to the copper seed crystal obtained in step S2 is 0.1 to 15:1, and the total mass concentration of the cuprous oxide precursor obtained in step S1 and the copper seed crystal obtained in step S2 in the mixed solution is 5 to 20%.

[0016] In step (2), the reaction temperature is 30-90℃, the reaction time is 1-10h, and the reaction is accompanied by stirring at a speed of 200-700rpm.

[0017] The volume ratio of the mixed solution, dispersant solution, and reducing agent solution is 50–200:50–200:10–100, the concentration of the dispersant solution is 0.1–80 mmol / L, and the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the cuprous oxide precursor is 1–10:1.

[0018] Furthermore, in step S1, the concentration of the copper-containing solution is 0.02–2 mol / L, the concentration of the dispersant solution is 0.1–80 mmol / L, and the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the copper-containing solution is 0.6–20:1.

[0019] Furthermore, in step S1, the reaction temperature is 30–90°C, the reaction time is 1–6 hours, and the reaction is accompanied by stirring at a speed of 200–700 rpm.

[0020] The volume ratio of the copper-containing solution, dispersant solution, and reducing agent solution is 100–500: 50–200: 100–500.

[0021] Furthermore, in step S2, the mass concentration of the cuprous oxide precursor solution is 0.05–40%, the concentration of the dispersant solution is 0.1–80 mmol / L, and the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the cuprous oxide precursor solution is 0.6–20:1.

[0022] Furthermore, in step S2, the reaction temperature is 30–90°C, the reaction time is 0.5–8 h, and the reaction is accompanied by stirring at a speed of 200–700 rpm.

[0023] The volume ratio of the cuprous oxide precursor solution, dispersant solution, and reducing agent solution is 50–200: 50–200: 100–300.

[0024] Furthermore, in step S3, the reaction temperature is 90–95°C, and the reaction time is 30–180 min;

[0025] The mass-to-volume ratio of the seed crystal, deoxygenated water solvent, and surface modifier is 1–10 g: 100–300 mL: 0.001–2 g; the protective gas includes nitrogen or argon.

[0026] Furthermore, the sources of copper ions in the copper-containing solution include one or more of copper sulfate, copper nitrate, copper chloride, copper hydroxide, copper acetate, and basic copper carbonate.

[0027] The surface modifier includes one or more of stearic acid, terpineol, rosin, benzotriazole, imidazole, OP-emulsifier, polyethylene glycol, oleic acid, and acetone.

[0028] Furthermore, the dispersants in steps S1, S2, and (2) independently include one or more of gelatin, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, triethylhexyl phosphate, sodium dodecyl sulfate, methylpentanol, polyacrylamide, guru gum, and fatty acid polyethylene glycol esters.

[0029] Furthermore, the reducing agents in steps S1, S2, and (2) independently include one or more of the following: sodium borohydride, sodium hypophosphite, glucose, formaldehyde, hydrazine hydrate, hydroquinone, pyrogallol, alkanolamine, hydrogen peroxide, L-ascorbic acid, lithium borohydride, sodium triacetoxyborohydride, dicarbonyldicyclopentadienyltitanium, diisocyanate camphorane, maltose, and citric acid.

[0030] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] 1. The method of preparing ultrafine copper powder according to the present invention has simple operation steps, short production process, milder reaction conditions, low reaction temperature, very low energy consumption, and little environmental pollution.

[0032] 2. The ultrafine copper powder prepared by this invention has a smooth surface, uniform particle size distribution, monodispersity and high crystallinity, good morphological consistency, and a purity of over 99% and a high tap density.

[0033] 3. The ultrafine copper powder prepared by this invention has both electrical conductivity and antioxidant properties, and has great application prospects in the electronics industry.

[0034] 4. The ultrafine copper powder prepared by this invention can freely control the particle size of the copper powder, and the size of the copper powder can be freely adjusted between 50 and 3000 nm. The ultrafine copper powder of any size has uniform size and consistent morphology, and the appropriate size of copper powder can be selected according to different application requirements. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the process for preparing ultrafine copper powder according to the present invention;

[0036] Figure 2 This is a SEM image of the copper seed crystals prepared in Example 1 at 10k magnification;

[0037] Figure 3 This is a SEM image of the copper seed crystals prepared in Example 1 at a magnification of 25k.

[0038] Figure 4 This is a SEM image of the copper seed crystals prepared in Example 2 at 10k magnification;

[0039] Figure 5 This is a SEM image of the copper seed crystals prepared in Example 2 at a magnification of 25k.

[0040] Figure 6 This is a SEM image of the cuprous oxide precursor prepared in Example 3 at 5k magnification;

[0041] Figure 7This is a SEM image of the cuprous oxide precursor prepared in Example 3 at 13k magnification;

[0042] Figure 8 This is a SEM image of the copper seed crystals prepared in Example 3 at a magnification of 20k.

[0043] Figure 9 This is a statistical result diagram of the physical size distribution of copper seed crystals obtained in Example 3;

[0044] Figure 10 This is the XRD characterization result of the copper seed crystals obtained in Example 3;

[0045] Figure 11 This is an SEM image of the ultrafine copper powder prepared from copper seed crystals in Example 3, taken at 5k magnification 3 minutes after the reduction reaction.

[0046] Figure 12 This is an SEM image of the ultrafine copper powder prepared from copper seed crystals in Example 3, taken 3 minutes after the reduction reaction. The image is magnified at 10k.

[0047] Figure 13 This is an SEM image of the ultrafine copper powder prepared from copper seed crystals in Example 3, taken 3 minutes after the reduction reaction. The image is magnified at 27k.

[0048] Figure 14 This is an SEM image of the ultrafine copper powder prepared from copper seed crystals in Example 3, taken 10 minutes after the reduction reaction. The image is magnified at 5k.

[0049] Figure 15 This is an SEM image of the ultrafine copper powder prepared from copper seed crystals in Example 3, taken 10 minutes after the reduction reaction. The image is magnified at 20k.

[0050] Figure 16 This is a SEM image of the ultrafine copper powder obtained in Example 3 at a magnification of 10k.

[0051] Figure 17 This is a statistical result diagram of the physical size distribution of the ultrafine copper powder finally obtained in Example 3;

[0052] Figure 18 This is the SEM image of the ultrafine copper powder obtained in Example 4 at a magnification of 10k.

[0053] Figure 19 This is a statistical result diagram of the physical size distribution of the ultrafine copper powder finally obtained in Example 4;

[0054] Figure 20 This is a SEM image of the ultrafine copper powder obtained in Example 5 at a magnification of 5k.

[0055] Figure 21 This is a statistical result diagram of the physical size distribution of the ultrafine copper powder finally obtained in Example 5;

[0056] Figure 22 This is the SEM image of the ultrafine copper powder obtained in Example 6 at a magnification of 10k.

[0057] Figure 23 This is a statistical result diagram of the physical size distribution of the ultrafine copper powder finally obtained in Example 6;

[0058] Figure 24 The image shows the SEM morphology of the ultrafine copper powder obtained in Comparative Example 1 at a magnification of 3k.

[0059] Figure 25 The image shows the SEM morphology of the ultrafine copper powder obtained in Comparative Example 1 at a magnification of 7k.

[0060] Figure 26 This is a SEM image of the ultrafine copper powder obtained in Comparative Example 2 at a magnification of 20k. Detailed Implementation

[0061] This invention provides a method for preparing monodisperse, highly crystalline, ultrafine copper powder, comprising the following steps:

[0062] S1. A copper-containing solution, a dispersant solution, and a reducing agent solution are mixed and reacted to obtain a cuprous oxide precursor.

[0063] S2. Copper seed crystals are obtained by mixing cuprous oxide precursor solution, dispersant solution and reducing agent solution and then reacting them.

[0064] S3. In a protective gas atmosphere, the seed crystals are mixed with deoxygenated water solvent and surface modifier and reacted to obtain monodisperse highly crystalline ultrafine copper powder.

[0065] The seed crystal is a copper seed crystal or a copper seed crystal with adjusted particle size.

[0066] In this invention, the copper seed crystals obtained in step S2 have a particle size of 50nm≤D≤436nm, preferably 80nm≤D≤400nm, and more preferably 100nm≤D≤300nm; the copper seed crystals after particle size adjustment have a particle size of 436nm<D≤3000nm.

[0067] The preparation steps of the copper seed crystals after particle size control are as follows:

[0068] (1) Mix the cuprous oxide precursor obtained in step S1, the copper seed crystal obtained in step S2, and water to obtain a mixed solution;

[0069] (2) The mixed solution, dispersant solution and reducing agent solution are mixed and reacted to obtain large-particle copper seed crystals;

[0070] The preferred size of the large-diameter copper seed crystals is 450nm≤D≤2600nm, and more preferably 500nm≤D≤2200nm;

[0071] In step (1), the molar ratio of the cuprous oxide precursor obtained in step S1 to the copper seed crystal obtained in step S2 is 0.1 to 15:1, preferably 1 to 12:1, and more preferably 3 to 10:1; the total mass concentration of the cuprous oxide precursor obtained in step S1 and the copper seed crystal obtained in step S2 in the mixed solution is 5 to 20%, preferably 8 to 16%, and more preferably 10 to 15%.

[0072] In step (2), the reaction temperature is 30-90°C, preferably 40-80°C, and more preferably 50-70°C; the reaction time is 1-10h, preferably 2-8h, and more preferably 3-7h; the reaction is accompanied by stirring, and the stirring speed is 200-700rpm, preferably 300-600rpm, and more preferably 400-500rpm;

[0073] In step (2), the mixed solution and the dispersant solution are first mixed to obtain reaction system C. An inorganic acid solution or an inorganic base is added to adjust the pH value of reaction system C to 4-13. The inorganic acid solution is preferably a sulfuric acid solution, and the concentration of the sulfuric acid solution is preferably 0.1-1 mol / L, more preferably 0.3-0.7 mol / L. The inorganic base solution is preferably a sodium hydroxide solution or ammonia water, more preferably a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is preferably 0.1-1 mol / L, more preferably 0.3-0.7 mol / L. The pH value of reaction system A is preferably 5-12, more preferably 8-10.

[0074] The volume ratio of the mixed solution, dispersant solution, and reducing agent solution is 50–200:50–200:10–100, preferably 80–160:80–160:20–80, and more preferably 100–150:100–150:40–60; the concentration of the dispersant solution is 0.1–80 mmol / L, preferably 0.5–70 mmol / L, and more preferably 1–50 mmol / L; the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the cuprous oxide precursor is 1–10:1, preferably 2–8:1, and more preferably 4–6:1.

[0075] In this invention, in step S1, the concentration of the copper-containing solution is 0.02–2 mol / L, preferably 0.05–1.6 mol / L, and more preferably 0.1–1.2 mol / L; the concentration of the dispersant solution is 0.1–80 mmol / L, preferably 0.5–70 mmol / L, and more preferably 1–50 mmol / L; the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the copper-containing solution is 0.6–20:1, preferably 1–18:1, and more preferably 5–15:1.

[0076] In this invention, in step S1, a copper-containing solution and a dispersant solution are first mixed to obtain reaction system A. An inorganic acid solution or an inorganic alkali is added to adjust the pH value of reaction system A to 4-13. The inorganic acid solution is preferably a sulfuric acid solution, and the concentration of the sulfuric acid solution is preferably 0.1-1 mol / L, more preferably 0.3-0.7 mol / L. The inorganic alkali solution is preferably a sodium hydroxide solution or ammonia water, more preferably a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is preferably 0.1-1 mol / L, more preferably 0.3-0.7 mol / L. The pH value of reaction system A is preferably 5-12, more preferably 8-10.

[0077] In this invention, in step S1, the reaction temperature is 30-90°C, preferably 40-80°C, and more preferably 50-70°C; the reaction time is 1-6 hours, preferably 2-5 hours, and more preferably 3-4 hours; the reaction is accompanied by stirring, and the stirring speed is 200-700 rpm, preferably 300-600 rpm, and more preferably 400-500 rpm.

[0078] The volume ratio of the copper-containing solution, dispersant solution, and reducing agent solution is 100–500:50–200:100–500, preferably 150–450:80–160:150–450, and more preferably 200–400:100–150:200–400.

[0079] In this invention, in step S2, the mass concentration of the cuprous oxide precursor solution is 0.05–40%, preferably 0.1–30%, more preferably 1–20%; the concentration of the dispersant solution is 0.1–80 mmol / L, preferably 0.5–70 mmol / L, more preferably 1–50 mmol / L; the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the cuprous oxide precursor solution is 0.6–20:1, preferably 1–16:1, more preferably 5–15:1.

[0080] In this invention, in step S2, the cuprous oxide precursor solution and the dispersant solution are first mixed to obtain reaction system B. An inorganic acid solution or an inorganic base is added to adjust the pH of reaction system B to 4-13. The inorganic acid solution is preferably a sulfuric acid solution, and the concentration of the sulfuric acid solution is preferably 0.1-1 mol / L, more preferably 0.3-0.7 mol / L. The inorganic base solution is preferably a sodium hydroxide solution or ammonia water, more preferably a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is preferably 0.1-1 mol / L, more preferably 0.3-0.7 mol / L. The pH of reaction system A is preferably 5-12, more preferably 8-10.

[0081] In this invention, in step S2, the reaction temperature is 30–90°C, preferably 40–80°C, and more preferably 50–70°C; the reaction time is 0.5–8 h, preferably 1–7 h, and more preferably 3–5 h; the reaction is accompanied by stirring, and the stirring speed is 200–700 rpm, preferably 300–600 rpm, and more preferably 400–500 rpm.

[0082] The volume ratio of the cuprous oxide precursor solution, dispersant solution, and reducing agent solution is 50–200:50–200:100–300, preferably 80–160:80–160:140–260, and more preferably 100–140:100–140:180–220.

[0083] In this invention, in step S3, the reaction temperature is 90-95°C, preferably 91-94°C, and more preferably 92-93°C; the reaction time is 30-180 min, preferably 50-150 min, and more preferably 80-120 min.

[0084] The mass-to-volume ratio of the seed crystal, deoxygenated aqueous solvent, and surface modifier is 1–10 g: 100–300 mL: 0.001–2 g, preferably 2–8 g: 120–260 mL: 0.01–1.5 g, and more preferably 4–6 g: 140–220 mL: 0.1–1.0 g; the protective gas includes nitrogen or argon, preferably nitrogen.

[0085] In this invention, before the reaction in step S3, the seed crystals are washed by centrifugation with distilled water 3 to 8 times, preferably 4 to 7 times, and more preferably 5 to 6 times, and then washed by centrifugation with anhydrous ethanol 1 to 5 times, preferably 2 to 4 times, and more preferably 3 times; the preparation steps of the deoxygenated water solvent are as follows: boil water, degas under vacuum, and remove oxygen from the boiling water to obtain the deoxygenated water solvent.

[0086] In this invention, after the reaction in step S3 is completed, the monodisperse highly crystalline ultrafine copper powder obtained from the reaction is dried. The drying temperature is 60-80°C, preferably 65-77°C, and more preferably 66-70°C. The drying time is 24-48 hours, preferably 28-42 hours, and more preferably 30-35 hours. The drying method is spray drying, freeze drying, vacuum drying, or drying under an inert atmosphere, preferably spray drying, freeze drying, or vacuum drying, and more preferably spray drying.

[0087] In this invention, the sources of copper ions in the copper-containing solution include one or more of copper sulfate, copper nitrate, copper chloride, copper hydroxide, copper acetate, and basic copper carbonate, preferably one or more of copper sulfate, copper nitrate, copper hydroxide, copper acetate, and basic copper carbonate, and more preferably one or more of copper sulfate, copper nitrate, copper acetate, and basic copper carbonate.

[0088] The surface modifier includes one or more of stearic acid, terpineol, rosin, benzotriazole, imidazole, OP-emulsifier, polyethylene glycol, oleic acid and acetone, preferably one or more of stearic acid, terpineol, rosin, imidazole, polyethylene glycol, oleic acid and acetone, and more preferably one or more of stearic acid, rosin, imidazole, polyethylene glycol and acetone.

[0089] In this invention, the dispersant in steps S1, S2, and step (2) independently includes one or more of gelatin, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, triethylhexylphosphate, sodium lauryl sulfate, methylpentanol, polyacrylamide, guru gum, and polyethylene glycol esters of fatty acids, preferably one or more of gelatin, gum arabic, polyvinylpyrrolidone, triethylhexylphosphate, sodium lauryl sulfate, polyacrylamide, guru gum, and polyethylene glycol esters of fatty acids, and more preferably one or more of gelatin, gum arabic, polyvinylpyrrolidone, triethylhexylphosphate, sodium lauryl sulfate, and polyethylene glycol esters of fatty acids.

[0090] In this invention, the reducing agents in steps S1, S2, and (2) independently include one or more of sodium borohydride, sodium hypophosphite, glucose, formaldehyde, hydrazine hydrate, hydroquinone, pyrogallol, alkanolamine, hydrogen peroxide, L-ascorbic acid, lithium borohydride, sodium triacetoxyborohydride, dicarbonyldicyclopentadienyl titanium, diisocyanate camphorane, maltose, and citric acid. Preferably, they are one or more of sodium borohydride, glucose, formaldehyde, hydroquinone, pyrogallol, hydrogen peroxide, L-ascorbic acid, lithium borohydride, dicarbonyldicyclopentadienyl titanium, diisocyanate camphorane, maltose, and citric acid. More preferably, they are one or more of sodium borohydride, glucose, formaldehyde, hydroquinone, pyrogallol, hydrogen peroxide, lithium borohydride, diisocyanate camphorane, maltose, and citric acid.

[0091] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0092] Example 1

[0093] 60g of copper sulfate was dissolved in 300mL of aqueous solution to obtain a copper sulfate solution; 5g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 7. Sodium borohydride was used as a reducing agent, and 60g of sodium borohydride was dissolved in 300mL of water to obtain a sodium borohydride solution. The mixed solution was heated to 80℃ and mechanically stirred at 700rpm. Then, the prepared sodium borohydride solution was added dropwise to the mixed solution at a rate of 100mL / min, and the reaction was allowed to proceed for 2 hours to obtain a cuprous oxide precursor.

[0094] The cuprous oxide precursor was washed three times by centrifugation with distilled water. 5g of the washed cuprous oxide precursor was ultrasonically dispersed in 100mL of water to obtain a cuprous oxide precursor solution. 0.5g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The cuprous oxide precursor solution and the polyvinylpyrrolidone solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 10. Using sodium hypophosphite as a reducing agent, 10g of sodium hypophosphite was dissolved in 200mL of water to obtain a sodium hypophosphite solution. The mixed solution was heated to 80℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the sodium hypophosphite solution was directly poured into the mixed solution, and the reaction was allowed to proceed for 4 hours to obtain copper seed crystals with a size of approximately 50nm.

[0095] Take 5g of copper seed crystals and wash them three times with distilled water by centrifugation, then wash them three times with anhydrous ethanol by centrifugation. Boil 200mL of deionized water and degas it under vacuum to remove dissolved oxygen. Then add the washed copper seed crystals to the deoxygenated deionized water, add 0.04g of benzotriazole and 0.05g of stearic acid, and heat to 90℃ for surface treatment. During the treatment, N2 is continuously introduced for protection. After reacting for 80min, vacuum dry the surface-treated copper powder particles by centrifugation and place them in a vacuum oven. Dry them under vacuum at 80℃ for 36h to obtain monodisperse highly crystalline ultrafine copper powder.

[0096] Depend on Figures 2-3 It can be seen that the copper seed crystals prepared in this embodiment have a particle size of about 50 nm, good dispersibility, and uniform particle size.

[0097] Example 2

[0098] 60g of copper sulfate was dissolved in 300mL of aqueous solution to obtain a copper sulfate solution; 5g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 14. Formaldehyde and sodium hypophosphite were used as reducing agents. 30g of formaldehyde and 30g of sodium hypophosphite were dissolved in 300mL of water to obtain a reducing agent solution. The mixed solution was heated to 80℃ and mechanically stirred at 500rpm. Then, the prepared reducing agent solution was added dropwise to the mixed solution at a rate of 80mL / min. The reaction was allowed to proceed for 2 hours to obtain a cuprous oxide precursor.

[0099] The cuprous oxide precursor was washed four times by centrifugation with distilled water. 5g of the washed cuprous oxide precursor was ultrasonically dispersed in 100mL of water to obtain a cuprous oxide precursor solution. 0.5g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The cuprous oxide precursor solution and the polyvinylpyrrolidone solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 9. Sodium borohydride and glucose were used as reducing agents. 5g of sodium borohydride and 5g of glucose were dissolved in 200mL of water to obtain a reducing agent solution. The mixed solution was heated to 80℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the reducing agent solution was directly poured into the mixed solution, and the reaction was allowed to proceed for 4 hours to obtain copper seed crystals with a size of approximately 150nm.

[0100] Take 5g of copper seed crystals and wash them three times with distilled water by centrifugation, then wash them three times with anhydrous ethanol by centrifugation. Boil 200mL of deionized water and degas it under vacuum to remove dissolved oxygen. Then add the washed copper seed crystals to the deoxygenated deionized water, add 0.04g of benzotriazole and 0.05g of stearic acid, and heat to 90℃ for surface treatment. During the treatment, N2 is continuously introduced for protection. After reacting for 80min, vacuum dry the surface-treated copper powder particles by centrifugation and place them in a vacuum oven to dry under vacuum at 80℃ for 30h to obtain monodisperse highly crystalline ultrafine copper powder.

[0101] Depend on Figures 4-5 It can be seen that the copper seed crystals prepared in this embodiment have a particle size of about 150 nm, exhibit a near-spherical morphology, good dispersibility, and uniform particle size.

[0102] Example 3

[0103] 60g of copper sulfate was dissolved in 300mL of aqueous solution to obtain a copper sulfate solution; 10g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 14. Using formaldehyde as a reducing agent, 60g of formaldehyde was dissolved in 300mL of water to obtain a formaldehyde solution. The mixed solution was heated to 80℃ and mechanically stirred at 500rpm. Then, the prepared reducing agent solution was added dropwise to the mixed solution at a rate of 100mL / min, and the reaction was allowed to proceed for 2 hours to obtain a cuprous oxide precursor.

[0104] The cuprous oxide precursor was washed five times by centrifugation with distilled water. 5g of the washed cuprous oxide precursor was ultrasonically dispersed in 100mL of water to obtain a cuprous oxide precursor solution. 1g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The cuprous oxide precursor solution and the polyvinylpyrrolidone solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 9. Using sodium borohydride as a reducing agent, 10g of sodium borohydride was dissolved in 200mL of water to obtain a sodium borohydride solution. The mixed solution was heated to 80℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the sodium borohydride solution was directly poured into the mixed solution, and the reaction was allowed to proceed for 4 hours to obtain copper seed crystals with a size of approximately 300nm.

[0105] 1g of washed cuprous oxide precursor and 4g of copper seed crystals with a particle size of approximately 300nm were ultrasonically dispersed in 100mL of water to obtain a mixed copper solution. 0.5g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The mixed copper solution and the polyvinylpyrrolidone solution were stirred at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 13. Using glucose and L-ascorbic acid as reducing agents, 2g of glucose and 2g of L-ascorbic acid were dissolved in 50mL of water to obtain a reducing agent solution. The mixed solution was heated to 80°C, placed in an oil bath, and mechanically stirred at 700 rpm. Then, a reducing agent solution was added dropwise to the mixed solution at a rate of 10 mL / min. The reaction was carried out for 2 hours to obtain large-particle-size copper nanoparticles with a size of about 700 nm.

[0106] Take 5g of nano-copper powder with a particle size of about 700nm, centrifuge and wash it three times with distilled water, and then centrifuge and wash it three times with anhydrous ethanol. Boil 200mL of deionized water, degas it under vacuum to remove dissolved oxygen, and then add the washed nano-copper powder to the deoxygenated deionized water. Add 0.04g of benzotriazole and 0.05g of stearic acid, and then heat it to 90℃ for surface treatment. During the treatment, N2 is continuously introduced for protection. After reacting for 80min, vacuum drying is used. After centrifugation, the surface-treated copper powder particles are placed in a vacuum oven and vacuum dried at 80℃ for 40h to obtain monodisperse highly crystalline ultrafine copper powder.

[0107] Depend on Figures 6-7As can be seen, the cuprous oxide prepared in this embodiment has an octahedral morphology, a smooth surface, and good dispersibility;

[0108] Depend on Figures 8-9 It can be seen that the copper seed crystals prepared in this embodiment have a particle size in the range of 0.361 μm with small particle size error, good particle size uniformity, excellent dispersibility, and a near-spherical morphology; Figure 10 It can be seen that the three strongest peaks of copper powder are particularly sharp, indicating high crystallinity, and the phase shows a pure copper phase;

[0109] Depend on Figure 11 It can be seen that the copper powder reaction is relatively rapid. Cuprous oxide uses copper nanocrystals as seeds, and the copper atoms generated from the decomposition and reduction of cuprous oxide adhere to the surface of the copper nanocrystals for secondary growth; from Figure 12 It can be seen that, after magnification, the decomposed cuprous oxide is more clearly visible, adhering to the copper nanocrystal seeds and promoting their secondary growth; from Figure 13 It can be seen that the decomposition and reduction of cuprous oxide produces copper atoms that adhere to the surface of the copper seed crystals, promoting their growth; from Figure 14 It can be seen that most of the cuprous oxide has been converted into copper, promoting the growth of copper nanocrystals, and the particle size of the copper nanocrystals has further increased; from Figure 15 It can be seen that after magnification, the number of cuprous oxide particles was greatly reduced, and their size was reduced to about 50 nm. On the contrary, the size of the copper nanocrystals increased further.

[0110] Depend on Figures 16-17 It can be seen that the obtained copper powder has a particle size of about 0.7 μm, a narrow particle size distribution range, excellent monodispersity, a spheroidal geometric morphology, and good particle size uniformity.

[0111] The antioxidant properties of the ultrafine copper powder obtained in this embodiment were analyzed by thermogravimetric analysis. The heating rate was 1℃ / min. It was found that the copper powder only showed significant weight gain at 150℃. In addition, no oxides were detected on the surface of the copper powder after it was placed at room temperature for 100 days, indicating that the copper powder prepared in this embodiment has excellent antioxidant properties.

[0112] Example 4

[0113] 60g of copper sulfate was dissolved in 300mL of aqueous solution to obtain a copper sulfate solution; 10g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 14. Using formaldehyde as a reducing agent, 60g of formaldehyde was dissolved in 300mL of water to obtain a formaldehyde solution. The mixed solution was heated to 80℃ and mechanically stirred at 500rpm. Then, the prepared formaldehyde solution was added dropwise to the mixed solution at a rate of 100mL / min. The reaction was allowed to proceed for 2 hours to obtain a cuprous oxide precursor.

[0114] The cuprous oxide precursor was washed five times by centrifugation with distilled water. 5g of the washed cuprous oxide precursor was ultrasonically dispersed in 100mL of water to obtain a cuprous oxide precursor solution. 1g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The cuprous oxide precursor solution and the polyvinylpyrrolidone solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 9. Using sodium borohydride as a reducing agent, 10g of sodium borohydride was dissolved in 200mL of water to obtain a sodium borohydride solution. The mixed solution was heated to 80℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the sodium borohydride solution was directly poured into the mixed solution, and the reaction was allowed to proceed for 4 hours to obtain copper seed crystals with a size of approximately 300nm.

[0115] 3g of washed cuprous oxide precursor and 4g of copper seed crystals with a particle size of approximately 300nm were ultrasonically dispersed in 100mL of water to obtain a mixed copper solution; 1g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The mixed copper solution and the polyvinylpyrrolidone solution were stirred and mixed at 500rpm to obtain a mixed solution. 0.5mol / L sodium hydroxide solution and 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution to bring the pH to 13. Using formaldehyde and L-ascorbic acid as reducing agents, 3g of formaldehyde and 2g of L-ascorbic acid were dissolved in 50mL of water to obtain a reducing agent solution. The mixed solution was heated to 70°C, placed in an oil bath, and mechanically stirred at 700 rpm. Then, a reducing agent solution was added dropwise to the mixed solution at a rate of 8 mL / min. The reaction was carried out for 3 hours to obtain large-particle-size copper nanoparticles with a size of about 900 nm.

[0116] Take 5g of nano-copper powder with a particle size of about 900nm, centrifuge and wash it three times with distilled water, and then centrifuge and wash it three times with anhydrous ethanol. Boil 200mL of deionized water, degas it under vacuum to remove dissolved oxygen, and then add the washed nano-copper powder to the deoxygenated deionized water. Add 0.04g of imidazole, and then heat it to 90℃ for surface treatment. During the treatment, N2 is continuously introduced for protection. After reacting for 80min, vacuum drying is used. After centrifugation, the surface-treated copper powder particles are placed in a vacuum oven and vacuum dried at 80℃ for 36h to obtain monodisperse highly crystalline ultrafine copper powder.

[0117] Depend on Figures 18-19 It can be seen that the copper powder obtained in this embodiment has a particle size of about 0.9 μm, a narrow particle size distribution range, excellent monodispersity, a spherical geometric morphology, and good particle size uniformity.

[0118] Example 5

[0119] 60g of copper sulfate was dissolved in 300mL of aqueous solution to obtain a copper sulfate solution; 10g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 14. Using formaldehyde as a reducing agent, 60g of formaldehyde was dissolved in 300mL of water to obtain a formaldehyde solution. The mixed solution was heated to 80℃ and mechanically stirred at 500rpm. Then, the prepared formaldehyde solution was added dropwise to the mixed solution at a rate of 100mL / min. The reaction was allowed to proceed for 2 hours to obtain a cuprous oxide precursor.

[0120] The cuprous oxide precursor was washed six times by centrifugation with distilled water. 5g of the washed cuprous oxide precursor was ultrasonically dispersed in 100mL of water to obtain a cuprous oxide precursor solution. 1g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The cuprous oxide precursor solution and the polyvinylpyrrolidone solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 9. Using sodium borohydride as a reducing agent, 10g of sodium borohydride was dissolved in 200mL of water to obtain a sodium borohydride solution. The mixed solution was heated to 80℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the sodium borohydride solution was directly poured into the mixed solution, and the reaction was allowed to proceed for 4 hours to obtain copper seed crystals with a size of approximately 300nm.

[0121] 6g of washed cuprous oxide precursor and 4g of copper seed crystals with a particle size of approximately 300nm were ultrasonically dispersed in 100mL of water to obtain a mixed copper solution; 1g of polyethylene glycol was dissolved in 100mL of water to obtain a polyethylene glycol solution. The mixed copper solution and the polyethylene glycol solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 11. Using maltose and L-ascorbic acid as reducing agents, 2g of maltose and 4g of L-ascorbic acid were dissolved in 50mL of water to obtain a reducing agent solution. The mixed solution was heated to 60°C, placed in an oil bath, and mechanically stirred at 500 rpm. Then, a reducing agent solution was added dropwise to the mixed solution at a rate of 6 mL / min. The reaction was carried out for 3 hours to obtain large-particle-size copper nanoparticles with a size of about 1600 nm.

[0122] Take 5g of nano-copper powder with a particle size of about 1600nm, centrifuge and wash it three times with distilled water, and then centrifuge and wash it three times with anhydrous ethanol. Boil 200mL of deionized water, degas it under vacuum to remove dissolved oxygen, and then add the washed nano-copper powder to the deoxygenated deionized water. Add 0.05g of benzotriazole, and then heat it to 90℃ for surface treatment. During the treatment, N2 is continuously introduced for protection. After reacting for 80min, vacuum drying is used. After centrifugation, the surface-treated copper powder particles are placed in a vacuum oven and vacuum dried at 80℃ for 36h to obtain monodisperse highly crystalline ultrafine copper powder.

[0123] Depend on Figures 20-21It can be seen that the copper powder obtained in this embodiment has a particle size of about 1.6 μm, a narrow particle size distribution range, excellent monodispersity, a spherical geometric morphology, and good particle size uniformity.

[0124] Example 6

[0125] 60g of copper sulfate was dissolved in 300mL of aqueous solution to obtain a copper sulfate solution; 10g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 14. Using formaldehyde as a reducing agent, 60g of formaldehyde was dissolved in 300mL of water to obtain a formaldehyde solution. The mixed solution was heated to 80℃ and mechanically stirred at 500rpm. Then, the prepared formaldehyde solution was added dropwise to the mixed solution at a rate of 100mL / min. The reaction was allowed to proceed for 2 hours to obtain a cuprous oxide precursor.

[0126] The cuprous oxide precursor was washed six times by centrifugation with distilled water. 5g of the washed cuprous oxide precursor was ultrasonically dispersed in 100mL of water to obtain a cuprous oxide precursor solution. 1g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The cuprous oxide precursor solution and the polyvinylpyrrolidone solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 9. Using sodium borohydride as a reducing agent, 10g of sodium borohydride was dissolved in 200mL of water to obtain a sodium borohydride solution. The mixed solution was heated to 80℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the sodium borohydride solution was directly poured into the mixed solution, and the reaction was allowed to proceed for 4 hours to obtain copper seed crystals with a size of approximately 300nm.

[0127] A mixed copper solution was prepared by ultrasonically dispersing 6g of washed cuprous oxide precursor and 4g of copper seed crystals with a particle size of approximately 300nm in 100mL of water. A polyvinylpyrrolidone solution was prepared by dissolving 1g of polyvinylpyrrolidone in 100mL of water. The mixed copper solution and polyvinylpyrrolidone solution were stirred at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide and dilute sulfuric acid were slowly added dropwise to the mixed solution until the pH reached 13. A reducing agent solution was prepared by dissolving 4g of formaldehyde and 4g of glucose in 50mL of water. The mixed solution was heated to 60℃, placed in an oil bath, and mechanically stirred at 500rpm. The reducing agent solution was then added dropwise at a rate of 4mL / min, and the reaction was allowed to proceed for 3 hours to obtain large-particle-size copper nanoparticles with a size of approximately 2000nm.

[0128] Take 5g of nano-copper powder with a particle size of about 2000nm, centrifuge and wash it three times with distilled water, and then centrifuge and wash it three times with anhydrous ethanol. Boil 200mL of deionized water, degas it under vacuum to remove dissolved oxygen, and then add the washed nano-copper powder to the deoxygenated deionized water. Add 0.05g of stearic acid, and then heat it to 90℃ for surface treatment. During the treatment, N2 is continuously introduced for protection. After reacting for 80min, vacuum drying is used. After centrifugation, the surface-treated copper powder particles are placed in a vacuum oven and vacuum dried at 80℃ for 36h to obtain monodisperse highly crystalline ultrafine copper powder.

[0129] Depend on Figures 22-23 It can be seen that the copper powder obtained in this embodiment has a particle size of about 2 μm, a narrow particle size distribution range, excellent monodispersity, a spherical geometric morphology, and good particle size uniformity.

[0130] Comparative Example 1

[0131] 40g of copper sulfate was dissolved in 200mL of aqueous solution to obtain a copper sulfate solution; 2g of polyvinylpyrrolidone was dissolved in 100mL of water to obtain a polyvinylpyrrolidone solution. The copper sulfate solution and polyvinylpyrrolidone were stirred and mixed at 500rpm to obtain a mixed solution. 0.5mol / L sodium hydroxide solution and 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution to achieve a pH of 13. Sodium borohydride was used as a reducing agent, and 40g of sodium borohydride was dissolved in 200mL of water to obtain a sodium borohydride solution. The mixed solution was heated to 80℃ and added dropwise to an oil bath at a rate of 40mL / min. The mixture was mechanically stirred at 500rpm, and the prepared sodium borohydride solution was added dropwise. The reaction was allowed to proceed for 3 hours to obtain a brownish-red copper powder.

[0132] Depend on Figures 24-25 It can be seen that the copper powder obtained in this comparative example has a large number of hard agglomerates, poor dispersion, complex and inconsistent morphology, large particle size, and large particle size difference.

[0133] Comparative Example 2

[0134] 40g of copper sulfate was dissolved in 200mL of aqueous solution to obtain a copper sulfate solution; 2g of gelatin was dissolved in 100mL of water to obtain a gelatin solution. The copper sulfate solution and gelatin solution were stirred and mixed at 500rpm to obtain a mixed solution. 0.5mol / L sodium hydroxide solution and 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution to achieve a pH of 13. Using glucose as a reducing agent, 60g of glucose was dissolved in 300mL of water to obtain a glucose solution. The mixed solution was heated to 60℃ and added dropwise to an oil bath at a rate of 40mL / min. The mixture was mechanically stirred at 500rpm, and the prepared glucose solution was added dropwise. The reaction was allowed to proceed for 4 hours to obtain yellow cuprous oxide particles.

[0135] Cuprous oxide particles were washed three times by centrifugation with distilled water. 10g of the washed cuprous oxide particles were ultrasonically dispersed in 100mL of water to obtain a cuprous oxide particle solution. 1g of polyvinyl alcohol was dissolved in 100mL of water to obtain a polyvinyl alcohol solution. The cuprous oxide particle solution and the polyvinyl alcohol solution were mixed by stirring at 500rpm to obtain a mixed solution. A 0.5mol / L sodium hydroxide solution and a 0.5mol / L dilute sulfuric acid solution were prepared to adjust the pH of the mixed solution. The 0.5mol / L sodium hydroxide solution and dilute sulfuric acid solution were slowly added dropwise to the mixed solution until the pH reached 7. Using hydrazine hydrate as a reducing agent, 40g of hydrazine hydrate was dissolved in 200mL of water to obtain a hydrazine hydrate solution. The mixed solution was heated to 85℃, placed in an oil bath, and mechanically stirred at 700rpm. Then, the hydrazine hydrate solution was added dropwise to the mixed solution at 200mL / min, and the reaction was allowed to proceed for 1 hour to obtain a brownish-red copper powder.

[0136] Take 5g of brownish-red copper powder and wash it 4 times by centrifugation with distilled water, then wash it 2 times by centrifugation with anhydrous ethanol; take 0.5g of benzotriazole and add it to 300mL of deionized water, soak the brownish-red copper powder in the above solution for one day, and then dry it under vacuum at 70℃ for 10h to obtain ultrafine copper powder.

[0137] Depend on Figure 26 It can be seen that the copper powder obtained in this comparative example has small spots on its surface, the surface of the copper powder is not smooth, the particle size of the copper powder is difficult to control, the particle size of the copper powder varies greatly, and the particle size is relatively uneven.

[0138] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing monodisperse, highly crystalline, ultrafine copper powder, characterized in that, Includes the following steps: S1. A copper-containing solution, a dispersant solution, and a reducing agent solution are mixed and reacted to obtain a cuprous oxide precursor. S2. The copper seed crystals are obtained by mixing the cuprous oxide precursor solution, the dispersant solution and the reducing agent solution and then reacting them. S3. In a protective gas atmosphere, the seed crystals are mixed with deoxygenated water solvent and surface modifier and reacted to obtain monodisperse highly crystalline ultrafine copper powder. The seed crystal is a copper seed crystal or a copper seed crystal with adjusted particle size; The copper seed crystals obtained in step S2 have a particle size of 50nm ≤ D ≤ 436nm; the copper seed crystals after particle size adjustment have a particle size of 436nm < D ≤ 3000nm. The preparation steps of the copper seed crystals after particle size control are as follows: (1) Mix the cuprous oxide precursor obtained in step S1, the copper seed crystal obtained in step S2, and water to obtain a mixed solution; (2) The mixed solution, dispersant solution and reducing agent solution are mixed and reacted to obtain large-particle copper seed crystals; In step S1, the copper-containing solution and the dispersant solution are first mixed to obtain reaction system A. An inorganic acid solution or an inorganic alkali is added to adjust the pH value of reaction system A to 4~13. The inorganic alkali solution is sodium hydroxide solution or ammonia water. In step S1, the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the copper-containing solution is 0.6~20:1; In step (1), the molar ratio of the cuprous oxide precursor obtained in step S1 to the copper seed crystal obtained in step S2 is 0.1~15:1, and the total mass concentration of the cuprous oxide precursor obtained in step S1 and the copper seed crystal obtained in step S2 in the mixed solution is 5~20%. In step (2), the reaction temperature is 30~90℃, the reaction time is 1~10h, and the reaction is accompanied by stirring at a speed of 200~700rpm. The volume ratio of the mixed solution, dispersant solution, and reducing agent solution is 50~200:50~200:10~100, the concentration of the dispersant solution is 0.1~80 mmol / L, and the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the cuprous oxide precursor is 1~10:

1. In step S1, the concentration of the copper-containing solution is 0.02~2 mol / L, and the concentration of the dispersant solution is 0.1~80 mmol / L; In step S2, the mass concentration of the cuprous oxide precursor solution is 0.05-40%, the concentration of the dispersant solution is 0.1-80 mmol / L, and the molar ratio of the reducing agent in the reducing agent solution to the copper ions in the cuprous oxide precursor solution is 0.6-20:

1. In step S2, the reaction temperature is 30~90℃, the reaction time is 0.5~8h, and the reaction is accompanied by stirring at a speed of 200~700rpm. The volume ratio of the cuprous oxide precursor solution, dispersant solution, and reducing agent solution is 50~200:50~200:100~300.

2. The preparation method according to claim 1, characterized in that, In step S1, the reaction temperature is 30~90℃, the reaction time is 1~6h, and the reaction is accompanied by stirring at a speed of 200~700rpm. The volume ratio of the copper-containing solution, dispersant solution, and reducing agent solution is 100~500:50~200:100~500.

3. The preparation method according to claim 1 or 2, characterized in that, In step S3, the reaction temperature is 90~95℃ and the reaction time is 30~180min; The mass-to-volume ratio of the seed crystal, deoxygenated water solvent, and surface modifier is 1~10g: 100~300mL: 0.001~2g; The protective gas includes nitrogen or argon.

4. The preparation method according to claim 3, characterized in that, The sources of copper ions in the copper-containing solution include one or more of copper sulfate, copper nitrate, copper chloride, copper hydroxide, copper acetate, and basic copper carbonate. The surface modifier includes one or more of stearic acid, terpineol, rosin, benzotriazole, imidazole, OP-emulsifier, polyethylene glycol, oleic acid, and acetone.

5. The preparation method according to claim 1, characterized in that, The dispersants in steps S1, S2 and (2) independently include one or more of gelatin, gum arabic, polyvinyl alcohol, polyvinylpyrrolidone, triethylhexyl phosphate, sodium dodecyl sulfate, methylpentanol, polyacrylamide, guru gum and fatty acid polyethylene glycol esters.

6. The preparation method according to claim 1 or 5, characterized in that, The reducing agents in steps S1, S2, and (2) independently include one or more of the following: sodium borohydride, sodium hypophosphite, glucose, formaldehyde, hydrazine hydrate, hydroquinone, pyrogallol, alkanolamine, hydrogen peroxide, L-ascorbic acid, lithium borohydride, sodium triacetoxyborohydride, dicarbonyldicyclopentadienyltitanium, diisocyanate camphorane, maltose, and citric acid.

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