A method for preparing polyhedral submicron copper powder

Abstract

This invention relates to a method for preparing polyhedral submicron copper powder, comprising the following steps: S1, mixing a copper salt solution and an alkaline solution uniformly, then adding a first reducing agent solution, and reacting under constant temperature and continuous stirring to obtain a cuprous oxide suspension; S2, adding a protective agent solution to the cuprous oxide suspension obtained in step S1, and then adding a second reducing agent solution under constant temperature and stirring to react; then, adding a third reducing agent solution dropwise at a uniform rate and continuing the reaction for a period of time to prepare a submicron copper powder dispersion; S3, separating, washing, and drying the submicron copper powder dispersion obtained in step S2 to obtain submicron copper powder dry powder. This preparation method can produce submicron-sized, narrow-sized, and well-dispersed polyhedral copper powder; and has the advantages of simple process flow, low cost, and suitability for mass production.

Description

Technical Field

[0001] This invention relates to the field of micro / nano powder material preparation technology, specifically to a method for preparing polyhedral submicron copper powder. Background Technology

[0002] Submicron copper powder (D50: 0.1~1μm) not only possesses the excellent electrical conductivity, thermal conductivity, corrosion resistance, antibacterial properties, and non-magnetic properties of copper metal, but also exhibits small size effect, low melting point, and high activity. It is widely used in powder metallurgy parts, MLCCs (multilayer ceramic chip capacitors), conductive coatings, electronic pastes, integrated circuit printing plates, shielding materials, lubricants, catalysts, and medical fields.

[0003] Submicron copper powder has broad application prospects in the market, with an annual demand of over 5,000 tons. With the popularization and upgrading of intelligent consumer electronics, the increasing level of automotive electronics brought about by new energy vehicles and autonomous driving technology, the promotion of 5G communication, the deepening of industrial automation, the advancement of additive manufacturing technology, and the development of the aerospace industry, the market demand for submicron copper powder will continue to increase.

[0004] Submicron copper powder can be prepared using either physical or chemical methods. Physical methods primarily include pulverization, vapor deposition, gamma-ray diffraction, plasma deposition, and spraying. Chemical methods mainly include chemical vapor deposition, sol-gel synthesis, electrolysis, liquid-phase chemical reduction, vapor-phase reduction, polyol reduction, and ammonium salt disproportionation. Currently, most synthesis processes cannot precisely control parameters such as crystal form, size, particle size distribution, and dispersibility of submicron copper powder particles, and the preparation processes are complex, failing to meet the technical requirements of specific applications. Therefore, developing a submicron copper powder preparation process that offers controllable size, specific crystal form, good dispersibility, and ease of mass production is of great significance. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing polyhedral submicron copper powder. This method can produce submicron-sized polyhedral copper powder with narrow particle size distribution and good dispersibility. The preparation method is simple, low-cost, and suitable for mass production.

[0006] Therefore, the present invention provides a method for preparing polyhedral submicron copper powder, comprising the following steps:

[0007] S1. Mix the copper salt solution and the alkaline solution evenly, then add the first reducing agent solution, and react under constant temperature and continuous stirring to obtain a cuprous oxide suspension.

[0008] S2. Add a protective agent solution to the cuprous oxide suspension prepared in step S1, and then add a second reducing agent solution under constant temperature and stirring conditions to react; then, add a third reducing agent solution dropwise at a uniform rate and continue to react for a period of time to prepare a submicron copper powder dispersion.

[0009] S3. The submicron copper powder dispersion prepared in step S2 is separated, washed and dried to obtain submicron copper powder dry powder.

[0010] Furthermore, the reducing properties of the second and third reducing agents are both stronger than those of the first reducing agent.

[0011] Furthermore, the first reducing agent includes one or more combinations selected from the group consisting of glucose, ethylene glycol, and ascorbic acid.

[0012] Furthermore, the concentration of the first reducing agent is 0.1 to 8 mol / L; for example, it can be about 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.6 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, etc.

[0013] Furthermore, the second reducing agent and the third reducing agent each independently comprise one or more combinations selected from the group consisting of hydrazine hydrate, hydrazine carbonate, formaldehyde, and sodium hypophosphite.

[0014] Furthermore, the concentrations of the second reducing agent solution and the third reducing agent solution are each independently 0.1 to 8 mol / L; for example, they can be about 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.6 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, etc.

[0015] Furthermore, the second reducing agent solution and the third reducing agent solution are the same.

[0016] Furthermore, in step S2, the volume ratio of the second reducing agent solution to the third reducing agent solution is 0.2 to 5:1; for example, it can be about 0.2:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc.

[0017] Those skilled in the art will know that copper salt solution refers to divalent copper salt solution.

[0018] Furthermore, the copper salt includes one or more combinations selected from the group consisting of copper chloride, copper nitrate, and copper sulfate; the concentration of the copper salt solution is 0.1–4 mol / L; for example, it can be about 0.1 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, etc.

[0019] Furthermore, the alkaline solution includes one or more combinations selected from the group consisting of: sodium hydroxide aqueous solution and potassium hydroxide aqueous solution; the concentration of the alkaline solution is 0.2 to 8 mol / L, and the alkaline solution is added until the pH is 10-14; for example, the alkaline solution is added until the pH is approximately 10, 11, 12, 13, 14, etc.

[0020] Furthermore, in step S1, the constant temperature condition is 50–130°C, for example, it can be about 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, etc.; the reaction time is 30–90 min, for example, it can be about 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, etc.

[0021] Furthermore, the protective agent comprises one or more combinations selected from the group consisting of: polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), sorbitol, sodium citrate, gelatin, gum arabic, benzotriazole (BTA), polyethylene glycol (PEG), and sodium dodecylbenzenesulfonate (SDBS).

[0022] Furthermore, the mass ratio of the protective agent to the copper element in cuprous oxide is 0.5 to 10:1; for example, it can be about 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1.

[0023] Furthermore, in step S2, the constant temperature condition is 50-80℃, for example, it can be about 50℃, 60℃, 70℃, 80℃, etc.; the total reaction time is 30-120min, for example, it can be about 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, etc.

[0024] Furthermore, in step S3, the detergent used for washing includes one or more combinations selected from the group consisting of ethanol, acetone, and pure water; the number of washing cycles is 3 to 4.

[0025] Furthermore, in step S3, the drying is vacuum drying; the temperature of the vacuum drying is 40-90℃, and the drying time is 1-6 hours.

[0026] Furthermore, the solvents for the copper salt solution, alkaline solution, first reducing agent, second reducing agent, third reducing agent, and protective agent solution are each independently selected from the group consisting of pure water, polyol, or a combination of pure water and polyol in a mass ratio of 0.5 to 4:1.

[0027] Furthermore, the polyol includes one or more combinations selected from the group consisting of ethylene glycol, propylene glycol, glycerol, etc.

[0028] Furthermore, the Dv50 particle size of the polyhedral submicron copper powder is 0.1 to 1 μm; for example, it can be about 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc.

[0029] In a second aspect, the present invention provides a polyhedral submicron copper powder, which is prepared by the preparation method described in the first aspect of the present invention.

[0030] Furthermore, the Dv50 particle size of the polyhedral submicron copper powder is 0.1 to 1 μm; for example, it can be about 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc.

[0031] Compared with existing technologies, the technical solution of the present invention has the following beneficial effects: the submicron copper powder prepared by the present invention has a polyhedral crystal structure and has the advantages of excellent dispersibility, no particle agglomeration, uniform particle size distribution, and good oxidation resistance. Furthermore, the preparation method provided by the present invention has a simple process flow, a yield exceeding 95%, and is suitable for large-scale industrial production. Attached Figure Description

[0032] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings:

[0033] Figure 1 Scanning electron microscope (SEM) image of the polyhedral submicron copper powder prepared in Example 1. Detailed Implementation

[0034] Exemplary embodiments of this disclosure will now be described in more detail. It should be understood that this disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0035] Example 1

[0036] This embodiment provides a polyhedral submicron copper powder, the preparation method of which is as follows:

[0037] (1) Add NaOH aqueous solution (concentration of 1 mol / L) to 1 L of 0.2 mol / L CuCl2 aqueous solution, stir continuously to form a precipitate and adjust the pH to 11. After heating to 50℃, add 500 mL of 0.6 mol / L glucose aqueous solution and continue to react for 30 min to obtain Cu2O suspension.

[0038] (2) Prepare 1L of 0.6mol / L hydrazine hydrate aqueous solution and divide it into two parts: solution A (300ml) and solution B (700ml);

[0039] (3) Add an aqueous solution containing 33.3g PVP to the Cu2O suspension and stir evenly. Heat to 70℃ and pour in solution A. After reacting for 10min, add solution B dropwise at a uniform rate and continue reacting for 90min to obtain a submicron copper powder dispersion.

[0040] (4) The submicron copper powder dispersion obtained in step (3) is subjected to sedimentation, filtration and separation, washed three times with ethanol and once with pure water, and then vacuum dried at 70°C for 3 hours to obtain the submicron copper powder product.

[0041] Example 2

[0042] This embodiment provides a polyhedral submicron copper powder, the preparation method of which is as follows:

[0043] (1) Add NaOH aqueous solution (concentration of 1 mol / L) to 1 L of 0.2 mol / L Cu(NO3)2 aqueous solution, stir continuously to form a precipitate and adjust the pH to 14. After heating to 80℃, add 500 mL of 1 mol / L ascorbic acid aqueous solution and continue the reaction for 30 min to obtain Cu2O suspension.

[0044] (2) Prepare 1L of 0.6mol / L hydrazine carbonate aqueous solution and divide it into two parts: solution A (250ml) and solution B (750ml);

[0045] (3) Add an aqueous solution containing 33.3g PVA to the Cu2O suspension and stir evenly. Heat to 80℃ and pour in solution A. After reacting for 10 min, add solution B dropwise at a uniform rate and continue reacting for 100 min to obtain a submicron copper powder dispersion.

[0046] (4) The submicron copper powder dispersion obtained in step (3) is subjected to sedimentation, filtration and separation, washed three times with ethanol and once with pure water, and then vacuum dried at 70°C for 3 hours to obtain the submicron copper powder product.

[0047] Example 3

[0048] This embodiment provides a polyhedral submicron copper powder, the preparation method of which is as follows:

[0049] (1) Add NaOH aqueous solution (concentration of 1 mol / L) to 1L of 0.5mol / L CuSO4 aqueous solution, stir continuously to form a precipitate and adjust the pH to 10. After heating to 50℃, add 500mL of 1.5mol / L glucose aqueous solution and continue to react for 30min to obtain Cu2O suspension.

[0050] (2) Prepare 1L of hydrazine hydrate aqueous solution with a concentration of 1.5mol / L, and divide it into two parts: solution A (300ml) and solution B (700ml);

[0051] (3) Add an aqueous solution containing 33.3g of sorbitol to the Cu2O suspension and stir evenly. Heat to 80℃ and pour in solution A. After reacting for 10min, add solution B dropwise at a uniform rate and continue reacting for 110min to obtain a submicron copper powder dispersion.

[0052] (4) The submicron copper powder dispersion obtained in step (3) is subjected to sedimentation, filtration and separation, washed three times with ethanol and once with pure water, and then vacuum dried at 70°C for 3 hours to obtain the submicron copper powder product.

[0053] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a polyhedral submicron copper powder, characterized by, Includes the following steps: S1. Mix the copper salt solution and the alkaline solution evenly, then add the first reducing agent solution, and react under constant temperature and continuous stirring to obtain a cuprous oxide suspension. S2. Add a protective agent solution to the cuprous oxide suspension prepared in step S1, and then pour in the second reducing agent solution under constant temperature and stirring conditions to react; then, add the third reducing agent solution dropwise at a uniform rate and continue to react for a period of time to prepare a submicron copper powder dispersion. S3. The submicron copper powder dispersion obtained in step S2 is separated, washed and dried to obtain submicron copper powder dry powder. In step S2, the protective agent includes one or more combinations selected from the group consisting of: polyvinyl alcohol, polyvinylpyrrolidone, sorbitol, sodium citrate, gelatin, gum arabic, benzotriazole, polyethylene glycol, and sodium dodecylbenzenesulfonate. The mass ratio of the protective agent to the copper element in cuprous oxide is 0.5~10:1; In step S2, the constant temperature condition is 70~80℃; The Dv50 particle size of the polyhedral submicron copper powder is 0.1–1 μm; The reducing properties of the second and third reducing agents are both stronger than those of the first reducing agent; The first reducing agent includes one or more combinations selected from the group consisting of glucose, ethylene glycol, and ascorbic acid; The second reducing agent and the third reducing agent each independently comprise one or more combinations selected from the group consisting of hydrazine hydrate, hydrazine carbonate, and sodium hypophosphite; The second reducing agent solution and the third reducing agent solution are the same; In step S1, the constant temperature condition is 50~130℃.

2. The production method according to claim 1, characterized by, The concentration of the first reducing agent is 0.1~8 mol / L.

3. The production method according to claim 1 or 2, characterized by, The concentrations of the second reducing agent solution and the third reducing agent solution are each independently 0.1~8 mol / L.

4. The preparation method according to claim 1 or 2, characterized in that, In step S2, the volume ratio of the second reducing agent solution to the third reducing agent solution is 0.2~5:

1.

5. The preparation method according to claim 1, characterized in that, The copper salt comprises one or more combinations selected from the group consisting of copper chloride, copper nitrate, and copper sulfate; the concentration of the copper salt solution is 0.1~4 mol / L.

6. The preparation method according to claim 1, characterized in that, The alkaline solution comprises one or more combinations selected from the group consisting of: sodium hydroxide aqueous solution and potassium hydroxide aqueous solution; the concentration of the alkaline solution is 0.2~8 mol / L, and the alkaline solution is added until the pH is 10-14.

7. The preparation method according to claim 1, characterized in that, In step S1, the reaction time is 30-90 minutes.

8. The preparation method according to claim 1, characterized in that, In step S2, the total reaction time is 30~120 min.

9. The preparation method according to claim 1, characterized in that, In step S3, the detergent used for washing includes one or more combinations selected from the group consisting of ethanol, acetone, and pure water; the number of washing cycles is 3 to 4.

10. The preparation method according to claim 1, characterized in that, In step S3, the drying is vacuum drying; the temperature of the vacuum drying is 40-90℃, and the drying time is 1-6h.

11. The preparation method according to claim 1, characterized in that, The solvents for the copper salt solution, alkaline solution, first reducing agent, second reducing agent, third reducing agent, and protective agent solution are each independently selected from the following group: pure water, polyol, or a combination of pure water and polyol in a mass ratio of 0.5 to 4:

1.

12. The preparation method according to claim 11, characterized in that, The polyols include one or more combinations selected from the group consisting of ethylene glycol, propylene glycol, and glycerol.

13. A polyhedral submicron copper powder, characterized in that, The polyhedral submicron copper powder is prepared by the preparation method according to any one of claims 1 to 12.

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