Antioxidant copper particles with oxalic acid compound-modified particle surface and preparation method thereof

Abstract

An antioxidant copper particle with an oxalic acid compound-modified surface and its preparation method are disclosed. The particle's outer surface is coated with a cuprous oxalate complex film, and the particle's interior contains elemental copper. The preparation method is as follows: First, copper particles are mixed evenly with a solution, then oxalic acid is added, and the solution is brought to a boil. At this time, oxalic acid reacts with elemental copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Heating is then stopped, and centrifugation and washing are performed sequentially to obtain the antioxidant copper particles with the oxalic acid compound-modified surface. In application, the cuprous oxalate complex film can protect the copper particles and prevent them from being oxidized, thus giving the copper particles antioxidant properties. The cuprous oxalate complex film is stable and will not age, degrade, or volatilize over time under normal conditions, thus maintaining stable antioxidant capacity, which is beneficial for the long-term preservation of copper particles. Therefore, the protective film designed in this way has stable antioxidant capacity and is beneficial for the long-term preservation of copper particles.

Description

Technical Field

[0001] This invention relates to an antioxidant copper particle, belonging to the field of antioxidant copper particles, and particularly to an antioxidant copper particle with an oxalic acid compound modified on the particle surface and its preparation method. Background Technology

[0002] Copper has similar electrical and thermal conductivity to silver, but at a lower cost. Therefore, copper sintered at high temperatures is becoming an important development direction for electrode materials in the photovoltaic and semiconductor fields. However, the fact that copper particles are easily oxidized in air limits their use. Therefore, copper particles need to be treated to resist oxidation.

[0003] Chinese patent application number 201110033990.5, filed on January 26, 2011, discloses a method for antioxidant processing of nano-copper particles. The steps include: preparing an aqueous solution of organic acid with a mass concentration of 0.1%–2%, controlling the pH of the solution between 1 and 5; adding copper particles to the organic acid aqueous solution, stirring continuously, then allowing it to stand, and filtering off the supernatant; preparing a copper particle corrosion inhibitor solution with a mass concentration of 0.1%–2%; and adding the copper particle slurry to the copper particle corrosion inhibitor solution. After thorough stirring and standing, the supernatant is filtered off to obtain a copper particle slurry. The copper particle slurry is then replaced 2-4 times with an organic solvent and classified. Alcohol-soluble organic matter, weighed at 0.1%-5% of the weight of the copper particles in the slurry, is dissolved in an alcohol solvent to prepare a 0.25%-5% copper particle corrosion inhibitor solution. The resulting copper particle slurry is added to the copper particle corrosion inhibitor solution, and the stirring time is 0.5-2 hours. Although this design achieves the purpose of copper particle oxidation resistance, it still has the following drawbacks:

[0004] This design forms a double-layer organic polymer protective film (water-soluble organic film + alcohol-soluble organic film) on the surface of copper particles. However, the properties of the organic polymer protective film are unstable and will age, degrade or volatilize over time. At this time, the organic polymer protective film loses its antioxidant capacity, which is not conducive to the long-term preservation of copper particles.

[0005] The information disclosed in this background section is intended only to enhance understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects and problems of unstable antioxidant capacity of protective films in the prior art, which is not conducive to the long-term preservation of copper particles, and to provide an antioxidant copper particle with oxalic acid compound modified particle surface and preparation method, which has stable antioxidant capacity of protective film and is conducive to the long-term preservation of copper particles.

[0007] To achieve the above objectives, the technical solution of the present invention is:

[0008] An antioxidant copper particle with an oxalic acid compound-modified surface, wherein the surface of the particle includes a cuprous oxalate complex film, the cuprous oxalate complex film comprising oxalate ions and copper ions connected by chemical bonds; and the interior of the particle is elemental copper.

[0009] A method for preparing antioxidant copper particles with oxalic acid compound-modified particle surfaces, the method comprising the following steps:

[0010] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, the reaction solution is obtained.

[0011] Step 2: First, add oxalate solution to the reaction solution, and then get a dark red mixture. Then heat the mixture until it boils. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of copper particles, and then get a pink liquid to be separated. Then stop heating the liquid to be separated.

[0012] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0013] In the first step, the copper particles comprise elemental copper or a mixture of elemental copper and copper oxide.

[0014] In the second step, the reaction of oxalate ions with elemental copper or copper ions means that: oxalate ions first react with copper oxides to generate free copper ions, and then oxalate ions react with elemental copper or copper ions.

[0015] In the first step, the alcohols include ethylene glycol, ethanol, or a mixture of ethylene glycol and ethanol;

[0016] In the first step, the reaction solution comprises one or more parts of copper particles, ethylene glycol, ethanol and water, wherein the mass-to-volume ratio of one part of copper particles, ethylene glycol, ethanol and water is 0.64-12.8g:0-40mL:0-40mL:0-40mL;

[0017] In the second step, the amount of oxalate compound in the oxalate solution corresponding to one part of copper particles, ethylene glycol, ethanol and water added is 0.126-2.52g.

[0018] In the first step, the mass-to-volume ratio of copper particles, ethylene glycol, ethanol, and water is 6.4 g: 40 mL: 0 mL: 0 mL.

[0019] In the second step, the oxalate solution is a solution containing oxalic acid dihydrate, sodium oxalate, or ammonium oxalate; in the first step, the water is deionized water.

[0020] In the first step, "mixing evenly" means mixing at a stirring speed of 500-1500 rpm for 0-10 minutes.

[0021] In the second step, boiling refers to a temperature of 78-197℃, a boiling duration of 30-60 minutes, and a stirring rate of 500-1500 rpm for the mixture.

[0022] In the second step, the thickness of the cuprous oxalate complex film is 60-100 nm.

[0023] In the second step, the thickness of the cuprous oxalate complex film is 80 nm.

[0024] In the third step, the centrifugation is performed at least twice.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. In the present invention, an antioxidant copper particle with an oxalic acid compound-modified particle surface and its preparation method, the surface of the particle includes a cuprous oxalate complex film, wherein the cuprous oxalate complex film consists of oxalate ions and copper ions linked by chemical bonds, and the interior of the particle is elemental copper. In application, the protective film of the present invention is a cuprous oxalate complex film located on the surface of the copper particle, which is sparingly soluble in water and can prevent the copper particle from contacting moisture and oxygen, thus giving the copper particle antioxidant properties. The advantages of the present invention also include:

[0027] Firstly, the cuprous oxalate complex film on the surface of copper particles enables the copper particles to have antioxidant properties.

[0028] Secondly, the cuprous oxalate complex membrane is stable and will not age, degrade, or volatilize over time under normal conditions, thus its antioxidant capacity is stable.

[0029] Thirdly, because the cuprous oxalate complex membrane has stable antioxidant capacity, it is beneficial for the long-term preservation of copper particles.

[0030] Fourthly, during the high-temperature sintering process of copper particles, cuprous oxalate decomposes to form cuprous oxide, which coats the surface of the copper particles. At this time, the copper particles regain their conductivity, and the cuprous oxide can protect the copper particles from being further oxidized to copper oxide.

[0031] Therefore, the protective film of the present invention has stable antioxidant properties and is beneficial for the long-term preservation of copper particles.

[0032] 2. The present invention discloses an antioxidant copper particle with oxalic acid compound-modified particle surface and its preparation method. The method includes the following steps: Step 1: First, copper particles are mixed evenly with solution No. 1 to obtain a reaction solution; Step 2: First, oxalate solution is added to the reaction solution to obtain a mixture, which is then heated until boiling. At this point, oxalate ions react with elemental copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles, resulting in a pink liquid to be separated, after which heating is stopped; Step 3: The liquid to be separated is centrifuged sequentially to obtain the antioxidant copper particle with oxalic acid compound-modified particle surface. The advantages of the present invention also include:

[0033] Firstly, this method can generate a cuprous oxalate complex film on the surface of copper particles, thereby giving the copper particles antioxidant properties.

[0034] Secondly, the prior art has a complex process with many separation steps and a long overall time consumption, while the present invention has fewer steps, a simpler process, and a shorter time consumption, making it more efficient; the prior art requires more complex raw materials, is slightly more expensive, and wastes more organic solvents, while the present invention uses cheaper raw materials and wastes less.

[0035] Therefore, the preparation method of the present invention is simple, efficient, and has a low preparation cost.

[0036] 3. In the present invention, an antioxidant copper particle with an oxalic acid compound-modified surface and its preparation method, in the first step, the copper particles include elemental copper or a mixture of elemental copper and copper oxide. In the second step, oxalate ions first react with copper oxide to generate free copper ions, and then react with elemental copper or copper ions to generate cuprous oxalate. In application, the oxalate ions first react with the copper oxide to expose a fresh, active, pure copper surface on the copper particles, laying the foundation for the subsequent generation of cuprous oxalate. Therefore, the present invention is also applicable to copper particles with oxidized surfaces.

[0037] 4. In the present invention, an antioxidant copper particle with oxalic acid compound modified particle surface and its preparation method, in the first step, the alcohol includes ethylene glycol, ethanol, or a mixture of ethylene glycol and ethanol. The reaction solution includes one or more parts of copper particles, ethylene glycol, ethanol, and water. The mass-to-volume ratio of one part of copper particles, ethylene glycol, ethanol, and water is 0.64-12.8 g: 0-40 mL: 0-40 mL: 0-40 mL. The amount of oxalic acid compound added to one part of copper particles, ethylene glycol, ethanol, and water in the oxalate solution is 0.126-2.52 g. In application, the copper particles are dispersed by ethylene glycol and ethanol, which helps... The subsequent reaction of oxalate ions with copper achieves the effect of coating the copper particle surface with a cuprous oxalate complex film. Multiple experiments were conducted based on the aforementioned mass-volume ratio to obtain strip-shaped and granular cuprous oxalate coatings on the copper particle surface. High-temperature sintering yielded plate-like, oriented, or porous cuprous oxide structures, respectively. Plate-like and oriented cuprous oxide exhibited superior antioxidant properties, while porous structures showed slightly weaker antioxidant properties. Therefore, the mass-volume ratio can be adjusted according to the antioxidant purpose to obtain oxalate-modified copper particle surfaces that meet the antioxidant requirements. Thus, the morphologies of the oxalate-modified copper particle surfaces prepared by this invention are diverse.

[0038] 5. In the present invention, an antioxidant copper particle with oxalic acid compound-modified particle surface and its preparation method, in the first step, uniform mixing means stirring at a stirring rate of 500-1500 rpm for 0-10 minutes. In the second step, boiling means a temperature of 78-197℃, a boiling duration of 30-60 minutes, and a stirring rate of 500-1500 rpm. In application, the boiling temperature of the first solution is related to the ratio of ethylene glycol, ethanol, and water in the first solution; a higher ethanol content results in a lower boiling temperature, and a higher ethylene glycol content results in a higher boiling temperature. A boiling duration of 30-60 minutes ensures complete reaction and maintains production rate. A stirring rate of 500-1500 rpm ensures uniform dispersion of copper particles and prevents splashing of the solution due to stirring. Stirring for 0-10 minutes is sufficient to uniformly disperse copper particles in the first solution. Therefore, the present invention has good reaction control.

[0039] 6. In the present invention, an antioxidant copper particle with oxalic acid compound-modified particle surface and its preparation method, in the second step, the thickness of the cuprous oxalate complex film is 60-100 nm, preferably 80 nm. When applied, a cuprous oxalate complex film thickness of 80 nm provides better antioxidant capacity, resulting in better long-term preservation. Furthermore, during subsequent sintering, no additional high temperature is required to decompose the cuprous oxalate into cuprous oxide, thereby restoring the conductivity of the copper particles while providing antioxidant properties. Therefore, the thickness of the cuprous oxalate complex film in this invention is suitable.

[0040] 7. In the method for preparing oxalic acid-modified copper oxide particles and their surface modification according to the present invention, the third step involves centrifugation at least twice, i.e., separation and washing at least twice. In application, oxalic acid-modified copper oxide particles are obtained through separation, followed by washing to remove unreacted oxalic acid and added alcohols from the surface of the copper particles. Separation and washing are then repeated to further remove impurities from the surface of the copper particles, ensuring the purity of the cuprous oxalate complex film on the surface of the copper particles. Therefore, the cuprous oxalate complex film of the present invention has high purity. Attached Figure Description

[0041] Figure 1 This is a flowchart of the present invention.

[0042] Figure 2 This is a schematic diagram of the parameters in Example 4.

[0043] Figure 3 This is a schematic SEM image of the antioxidant copper particles with oxalic acid compound modified on the surface of the particles obtained in Example 7.

[0044] Figure 4 This is a schematic SEM image of the antioxidant copper particles with oxalic acid compound modified on the particle surface obtained in Example 8.

[0045] Figure 5 This is a schematic SEM image of the antioxidant copper particles with oxalic acid compound modified on the particle surface obtained in Example 9.

[0046] Figure 6 This is a schematic SEM image of the antioxidant copper particles with oxalic acid compound modified on the particle surface obtained in Example 10.

[0047] Figure 7 This is a schematic SEM image of the antioxidant copper particles with oxalic acid compound modified on the surface of the particles obtained in Example 11.

[0048] Figure 8 This is a schematic SEM image of the antioxidant copper particles with oxalic acid compound modified on the surface of the particles obtained in Example 12.

[0049] Figure 9 This is the X-ray diffraction (XRD) pattern of Example 12.

[0050] Figure 10 These are X-ray diffraction (XRD) spectra and physical images of the present invention before and after sintering. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Please see Figure 1 — Figure 10 An antioxidant copper particle with an oxalic acid compound-modified surface, wherein the surface of the particle includes a cuprous oxalate complex film, the cuprous oxalate complex film comprising oxalate ions and copper ions connected by chemical bonds; and the interior of the particle is elemental copper.

[0053] A method for preparing antioxidant copper particles with oxalic acid compound-modified particle surfaces, the method comprising the following steps:

[0054] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, the reaction solution is obtained.

[0055] Step 2: First, add oxalate solution to the reaction solution, and then get a dark red mixture. Then heat the mixture until it boils. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of copper particles, and then get a pink liquid to be separated. Then stop heating the liquid to be separated.

[0056] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0057] In the first step, the copper particles comprise elemental copper or a mixture of elemental copper and copper oxide.

[0058] In the second step, the reaction of oxalate ions with elemental copper or copper ions means that: oxalate ions first react with copper oxides to generate free copper ions, and then oxalate ions react with elemental copper or copper ions.

[0059] In the first step, the alcohols include ethylene glycol, ethanol, or a mixture of ethylene glycol and ethanol;

[0060] In the first step, the reaction solution comprises one or more parts of copper particles, ethylene glycol, ethanol and water, wherein the mass-to-volume ratio of one part of copper particles, ethylene glycol, ethanol and water is 0.64-12.8g:0-40mL:0-40mL:0-40mL;

[0061] In the second step, the amount of oxalate compound in the oxalate solution corresponding to one part of copper particles, ethylene glycol, ethanol and water added is 0.126-2.52g.

[0062] In the first step, the mass-to-volume ratio of copper particles, ethylene glycol, ethanol, and water is 6.4 g: 40 mL: 0 mL: 0 mL.

[0063] In the second step, the oxalate solution is a solution containing oxalic acid dihydrate, sodium oxalate, or ammonium oxalate; in the first step, the water is deionized water.

[0064] In the first step, "mixing evenly" means mixing at a stirring speed of 500-1500 rpm for 0-10 minutes.

[0065] In the second step, boiling refers to a temperature of 78-197℃, a boiling duration of 30-60 minutes, and a stirring rate of 500-1500 rpm for the mixture.

[0066] In the second step, the thickness of the cuprous oxalate complex film is 60-100 nm.

[0067] In the second step, the thickness of the cuprous oxalate complex film is 80 nm.

[0068] In the third step, the centrifugation is performed at least twice.

[0069] The following are supplementary descriptions of the present invention:

[0070] The high-temperature sintering process of the copper particles described in this invention refers to the high-temperature sintering of copper particles with oxalic acid compound-modified surface in an oxygen-free environment. During this process, cuprous oxalate decomposes into cuprous oxide, which coats the surface of the copper particles. The cuprous oxide protects the copper from further oxidation. Multiple experiments have shown that cuprous oxide is not oxidized to copper oxide. X-ray diffraction (XRD) spectra and physical images before and after sintering are shown below. Figure 10 As shown, the phase structure exhibits characteristic peaks of copper, indicating that the main substance is copper. No black copper oxide impurities are observed in the physical image, thus demonstrating the antioxidant properties of this invention. The thickness of cuprous oxalate complex film can be controlled to adjust the thickness of cuprous oxide. When the thickness of cuprous oxide is less than 10 nanometers, electrons can tunnel through, thus restoring the conductivity of the copper particles. The product obtained after high-temperature sintering can be used as an electrode material for photovoltaics and semiconductors.

[0071] The oxalic acid compound mentioned in this invention refers to: cuprous oxalate complex membrane.

[0072] The diameter of the copper particles described in this invention is preferably 1-3 μm.

[0073] Example 1:

[0074] Please see Figure 1 — Figure 10An antioxidant copper particle with an oxalic acid compound-modified surface, wherein the surface of the particle includes a cuprous oxalate complex film, the cuprous oxalate complex film comprising oxalate ions and copper ions connected by chemical bonds; and the interior of the particle is elemental copper.

[0075] Preferably, the chemical bond refers to a coordinate bond.

[0076] Preferably, the cuprous oxalate complex membrane refers to cuprous oxalate crystals.

[0077] A method for preparing antioxidant copper particles with oxalic acid compound-modified particle surfaces, the method comprising the following steps:

[0078] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, the reaction solution is obtained.

[0079] Step 2: First, add oxalate solution to the reaction solution, and then get a dark red mixture. Then heat the mixture until it boils. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of copper particles, and then get a pink liquid to be separated. Then stop heating the liquid to be separated.

[0080] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0081] Example 2:

[0082] The basic content is the same as in Example 1, except that:

[0083] Please see Figure 1 — Figure 10 In the first step, the copper particles include elemental copper or a mixture of elemental copper and copper oxide; in the second step, the reaction of oxalate ions with elemental copper or copper ions means that: oxalate ions first react with copper oxide to generate free copper ions, and then the oxalate ions react with elemental copper or copper ions.

[0084] In application, the surface of copper particles is oxidized to form copper oxides, including copper oxide or cuprous oxide. Oxalate ions first react with copper oxides to produce monovalent copper ions. Then, oxalate ions react with monovalent copper ions and exposed elemental copper to form cuprous oxalate and copper oxalate, thus forming a cuprous oxalate complex film. Because oxalic acid has reducing properties, there is more cuprous oxalate and less copper oxalate, thereby giving the copper particles antioxidant properties.

[0085] Example 3:

[0086] The basic content is the same as in Example 1, except that:

[0087] Please see Figure 1 — Figure 10 In the first step, the alcohols include ethylene glycol, ethanol, or a mixture of ethylene glycol and ethanol. In the first step, the reaction solution comprises one or more parts of copper particles, ethylene glycol, ethanol, and water, with a mass-to-volume ratio of 0.64-12.8 g: 0-40 mL: 0-40 mL: 0-40 mL. In the second step, the amount of oxalate compound added to the oxalate solution corresponding to one part of copper particles, ethylene glycol, ethanol, and water is 0.126-2.52 g. In the first step, the mass-to-volume ratio of one part of copper particles, ethylene glycol, ethanol, and water is 6.4 g: 40 mL: 0 mL: 0 mL. In the second step, the oxalate solution is a solution including oxalic acid dihydrate, sodium oxalate, or ammonium oxalate. In the first step, the water is deionized water.

[0088] In application, copper particles are first dispersed using ethylene glycol, ethanol, or a mixture of ethylene glycol and ethanol to prevent particle adhesion and ensure proper coating of the copper particle surface by the cuprous oxalate complex film. The mass-to-volume ratio of copper particles, ethylene glycol, ethanol, and water is 0.64-12.8 g : 0-40 mL : 0-40 mL : 0-40 mL. 0.64-12.8 g of copper particles can be uniformly dispersed in 0-40 mL of ethylene glycol, ethanol, or water, and this 0-40 mL provides the liquid-phase reaction conditions for boiling. The amount of oxalate compound added to the oxalate solution corresponding to the aforementioned mass-to-volume ratio is 0.126-2.52 g. If the amount of oxalate ions added is less than 0.126 g, then... It is difficult to form a complete cuprous oxalate complex film on the surface of copper particles. If the amount of oxalate ions added is greater than 2.52g, the formed cuprous oxalate complex film will be too thick, resulting in an excessively thick cuprous oxide film during high-temperature sintering, which will reduce the conductivity of the copper particles. For copper particles that require high-temperature sintering, the optimal mass-to-volume ratio obtained in the experiment is 6.4g:40mL:0mL:0mL, corresponding to an oxalate ion addition of 0.63g. This yields a cuprous oxalate complex film of suitable thickness. The oxalate solution is a solution containing compounds containing oxalate ions. The compounds containing oxalate ions are selected as oxalic acid dihydrate, sodium oxalate, or ammonium oxalate for easy storage and acquisition. The water is deionized water to avoid introducing other impurities.

[0089] Example 4:

[0090] The basic content is the same as in Example 1, except that:

[0091] Please see Figure 1 — Figure 10In the first step, "mixing evenly" means stirring at a stirring rate of 500-1500 rpm for 0-10 minutes; in the second step, "boiling" means a temperature of 78-197℃, a boiling duration of 30-60 minutes, and a stirring rate of 500-1500 rpm for the mixture.

[0092] In the second step of application, the boiling temperature of the mixture is affected by the ratio of ethylene glycol, ethanol, and water in solution one. Ethanol has a boiling point of approximately 78°C, ethylene glycol approximately 197°C, and water approximately 100°C, therefore the boiling temperature is 78-197°C. Simultaneously, the stirring speed of the mixture is 500-1500 rpm to ensure uniform dispersion of the copper particles and prevent adhesion. The stirring speed is directly proportional to the mass of the copper particles. If the stirring speed is below 500 rpm, it will be difficult to achieve uniform mixing. Furthermore, since the experiment is conducted under magnetic stirring, if the magnetic stirrer has insufficient power, the stir bar may not be able to rotate due to resistance. If the stirring speed is above 1500 rpm, the mixture may splash onto the bottle wall or other areas, causing waste and posing a safety hazard. The preferred stirring speed is 1000 rpm, at which point the dispersion effect of the copper particles is better. The boiling time should be 30-60 minutes. Generally, after the mixture turns pink, continue heating for 30 minutes to ensure complete reaction. If the boiling time is less than 30 minutes, the reaction is incomplete, and the resulting cuprous oxalate complex film cannot completely coat the copper particles. If the boiling time is greater than 60 minutes, the reaction time is too long, wasting reaction time. The boiling time is also related to the ratio of ethylene glycol, ethanol, and water. If the first solution contains only ethylene glycol and water, the reaction time is 30 minutes. If the first solution contains only ethanol, the reaction time is 60 minutes. In the first step, the reaction solution is stirred at a stirring rate of 500-1500 rpm for 0-10 minutes to ensure that the copper particles are evenly dispersed in the reaction solution. The stirring rate is preferably 1000 rpm, and the stirring time is preferably 10 minutes. If the stirring time is too long, the production efficiency will decrease.

[0093] Example 5:

[0094] The basic content is the same as in Example 1, except that:

[0095] Please see Figure 1 — Figure 10 In the second step, the thickness of the cuprous oxalate complex film is 60-100 nm. Preferably, in the second step, the thickness of the cuprous oxalate complex film is 80 nm.

[0096] In application, if the thickness of the cuprous oxalate complex film is less than 60 nm, the antioxidant properties decrease, which is not conducive to the preservation of copper particles. If the thickness of the cuprous oxalate complex film is greater than 100 nm, the heating temperature required in the subsequent high-temperature sintering process will be higher, and the thicker cuprous oxalate complex film will consume more oxalic acid, leading to increased costs. The preferred thickness of the cuprous oxalate complex film is 80 nm, at which point a balance is achieved between antioxidant properties and ease of subsequent reactions is reached. The thickness of the cuprous oxalate complex film can be controlled by adjusting the reaction time; for example, the longer the reaction time, the thicker the cuprous oxalate complex film. Alternatively, the thickness of the cuprous oxalate complex film can be controlled by adjusting the mass-volume ratio and the amount of oxalic acid added; for example, a larger amount of oxalic acid added results in a thicker cuprous oxalate complex film.

[0097] Example 6:

[0098] The basic content is the same as in Example 1, except that:

[0099] Please see Figure 1 — Figure 10 In the third step, the centrifugation is performed at least twice. Preferably, the centrifugation speed is 8000 rpm and the duration is 5 minutes. Preferably, the washing solution used in the centrifugation operation is anhydrous ethanol and deionized water.

[0100] In application, unreacted oxalic acid and alcohols on the surface of the copper antioxidant particles modified with oxalic acid compounds are removed by repeated centrifugation. When the centrifugation speed is 8000 rpm and the time is 5 min, the separation is relatively rapid and the separation effect is good.

[0101] Example 7:

[0102] The basic content is the same as in Example 1, except that:

[0103] Please see Figure 1 — Figure 3 An antioxidant copper particle with oxalic acid compound modified on its surface and its preparation method, the method comprising the following steps:

[0104] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, a reaction solution is obtained. In the reaction solution, the mass-volume ratio of one part copper particles, ethylene glycol, ethanol and water is 6.4g:40mL:0mL:0mL.

[0105] Step 2: First, add oxalate solution to the reaction solution. The amount of oxalate compound in the oxalate solution corresponds to 0.63g of copper particles, ethylene glycol, ethanol and water. Then, a dark red mixture is obtained. The mixture is then heated until it boils for 30 minutes. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Then, a pink liquid to be separated is obtained. Then, heating of the liquid to be separated is stopped.

[0106] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0107] In application, the surface of the antioxidant copper particles obtained through this experimental step is coated with many strips of cuprous oxalate, and the cuprous oxalate coating is relatively dense.

[0108] Example 8:

[0109] The basic content is the same as in Example 1, except that:

[0110] Please see Figure 1 — Figure 4 An antioxidant copper particle with oxalic acid compound modified on its surface and its preparation method, the method comprising the following steps:

[0111] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, a reaction solution is obtained. In the reaction solution, the mass-volume ratio of one part copper particles, ethylene glycol, ethanol and water is 6.4g:40mL:0mL:0mL.

[0112] Step 2: First, add oxalate solution to the reaction solution. The amount of oxalate compound in the oxalate solution corresponds to 1.26g of copper particles, ethylene glycol, ethanol and water. Then, a dark red mixture is obtained. The mixture is then heated until it boils for 30 minutes. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Then, a pink liquid to be separated is obtained. Then, heating of the liquid to be separated is stopped.

[0113] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0114] In application, the surface of the antioxidant copper particles obtained through this experimental step is coated with many strips of cuprous oxalate, and the coating of cuprous oxalate is denser than that in Example 7.

[0115] Example 9:

[0116] The basic content is the same as in Example 1, except that:

[0117] Please see Figure 1 — Figure 5 An antioxidant copper particle with oxalic acid compound modified on its surface and its preparation method, the method comprising the following steps:

[0118] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, a reaction solution is obtained. In the reaction solution, the mass-volume ratio of one part copper particles, ethylene glycol, ethanol and water is 6.4g:40mL:0mL:0mL.

[0119] Step 2: First, add oxalate solution to the reaction solution. The amount of oxalate compound in the oxalate solution corresponds to 1.89g of copper particles, ethylene glycol, ethanol and water. Then, a dark red mixture is obtained. The mixture is then heated until it boils for 30 minutes. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Then, a pink liquid to be separated is obtained. Then, heating of the liquid to be separated is stopped.

[0120] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0121] Preferably, the mass ratio of the copper particles to the amount of oxalic acid added is 6.4g:0.63-1.89g.

[0122] In application, the copper oxide particles obtained through this experimental step have fewer strip-shaped cuprous oxalate on their surface and are instead coated with very dense granular cuprous oxalate. Examples 7-9 are control experiments with gradually increasing oxalic acid addition, resulting in copper oxide particles coated with strip-shaped or granular cuprous oxalate. During the subsequent high-temperature sintering process, the strip-shaped cuprous oxalate releases gas along the length of the strip during decomposition, which is more concentrated. After decomposition, the cuprous oxide is arranged in flakes or in a directional manner, resulting in better coating of the copper substrate. Although the granular cuprous oxalate can be densely coated, the gas release path is dispersed, which may form a porous protective layer after sintering, thus affecting its antioxidant properties.

[0123] Example 10:

[0124] The basic content is the same as in Example 1, except that:

[0125] Please see Figure 1 — Figure 6 An antioxidant copper particle with oxalic acid compound modified on its surface and its preparation method, the method comprising the following steps:

[0126] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, a reaction solution is obtained. In the reaction solution, the mass-volume ratio of one part copper particles, ethylene glycol, ethanol and water is 6.4g:0mL:40mL:0mL.

[0127] Step 2: First, add oxalate solution to the reaction solution. The amount of oxalate compound in the oxalate solution corresponds to 1.26g of copper particles, ethylene glycol, ethanol and water. Then, a dark red mixture is obtained. The mixture is then heated until it boils for 40 minutes. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Then, a pink liquid to be separated is obtained. Then, heating of the liquid to be separated is stopped.

[0128] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0129] When applied, the surface of the antioxidant copper particles obtained through this experimental step is coated with granular cuprous oxalate, but it is not as dense as in Example 9. At the same time, many strip-shaped and unevenly distributed cuprous oxalate particles can be seen. This example is a control experiment of Example 8, changing the ratio of alcohols to explore the optimal liquid phase environment for the reaction.

[0130] Example 11:

[0131] The basic content is the same as in Example 1, except that:

[0132] Please see Figure 1 — Figure 7 An antioxidant copper particle with oxalic acid compound modified on its surface and its preparation method, the method comprising the following steps:

[0133] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, a reaction solution is obtained. In the reaction solution, the mass-volume ratio of one part copper particles, ethylene glycol, ethanol and water is 0.64g:15mL:15mL:0mL.

[0134] Step 2: First, add oxalate solution to the reaction solution. The amount of oxalate compound in the oxalate solution corresponds to 0.126g of copper particles, ethylene glycol, ethanol and water. Then, a dark red mixture is obtained. The mixture is then heated until it boils for 40 minutes. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Then, a pink liquid to be separated is obtained. Then, heating of the liquid to be separated is stopped.

[0135] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0136] When applied, the surface morphology of the antioxidant copper particles obtained through this experimental step is uneven. Some surfaces have granular cuprous oxalate adhering to them, while others are covered with a thin film (which is an organic material). This example is a trial experiment with different mass-to-volume ratios in order to find the best mass-to-volume ratio.

[0137] Example 12:

[0138] The basic content is the same as in Example 1, except that:

[0139] Please see Figure 1 — Figure 9 An antioxidant copper particle with oxalic acid compound modified on its surface and its preparation method, the method comprising the following steps:

[0140] Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No. 1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, a reaction solution is obtained. In the reaction solution, the mass-volume ratio of one part copper particles, ethylene glycol, ethanol and water is 12.8g:0mL:40mL:40mL.

[0141] Step 2: First, add oxalate solution to the reaction solution. The amount of oxalate compound in the oxalate solution corresponds to 1.26g of copper particles, ethylene glycol, ethanol and water. Then, a dark red mixture is obtained. The mixture is then heated until it boils for 60 minutes. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of the copper particles. Then, a pink liquid to be separated is obtained. Then, heating of the liquid to be separated is stopped.

[0142] Step 3: First, centrifuge the liquid to be separated sequentially to obtain antioxidant copper particles with oxalic acid compound modified on the particle surface.

[0143] In application, the copper oxide particles obtained through this experimental step all have granular cuprous oxalate on their surface, but the surface morphology is uneven. Some are densely coated with small particles, while others are sparsely coated with large particles. This embodiment is an attempt to scale up the experiment, using water and ethanol, which are cheaper and less polluting, as solvents to prepare the copper oxide. The X-ray diffraction test results of the copper oxide particles obtained in this embodiment are as follows. Figure 9 The main component of the antioxidant copper particles is copper.

[0144] The above description is only a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. Any equivalent modifications or changes made by those skilled in the art based on the content disclosed in the present invention should be included within the scope of protection set forth in the claims.

Claims

1. An antioxidant copper particle with an oxalic acid compound-modified particle surface, characterized in that: The surface of the particle includes a cuprous oxalate complex film, which comprises oxalate ions and copper ions connected by chemical bonds; the interior of the particle is elemental copper.

2. A method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface as described in claim 1, characterized in that: The method includes the following steps: Step 1: First, mix the copper particles with solution No. 1 evenly to disperse the copper particles in solution No.

1. Solution No. 1 is an alcohol, water, or a mixture of alcohol and water. Then, the reaction solution is obtained. Step 2: First, add oxalate solution to the reaction solution, and then get a dark red mixture. Then heat the mixture until it boils. At this time, oxalate ions react with copper or copper ions to form a cuprous oxalate complex film on the surface of copper particles, and then get a pink liquid to be separated. Then stop heating the liquid to be separated. Step 3: First, centrifuge and wash the liquid to be separated in sequence to obtain copper oxide particles with oxalic acid compound modified on the particle surface.

3. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 2, characterized in that: In the first step, the copper particles comprise elemental copper or a mixture of elemental copper and copper oxide. In the second step, the reaction of oxalate ions with elemental copper or copper ions means that: oxalate ions first react with copper oxides to generate free copper ions, and then oxalate ions react with elemental copper or copper ions.

4. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 3, characterized in that: In the first step, the alcohols include ethylene glycol, ethanol, or a mixture of ethylene glycol and ethanol; In the first step, the reaction solution comprises one or more parts of copper particles, ethylene glycol, ethanol and water, wherein the mass-to-volume ratio of one part of copper particles, ethylene glycol, ethanol and water is 0.64-12.8g:0-40mL:0-40mL:0-40mL; In the second step, the amount of oxalate compound in the oxalate solution corresponding to one part of copper particles, ethylene glycol, ethanol and water added is 0.126-2.52g.

5. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 4, characterized in that: In the first step, the mass-to-volume ratio of copper particles, ethylene glycol, ethanol, and water is 6.4 g: 40 mL: 0 mL: 0 mL.

6. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 4, characterized in that: In the second step, the oxalate solution is a solution containing oxalic acid dihydrate, sodium oxalate, or ammonium oxalate; in the first step, the water is deionized water.

7. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 2, characterized in that: In the first step, "mixing evenly" means mixing at a stirring speed of 500-1500 rpm for 0-10 minutes. In the second step, boiling refers to a temperature of 78-197℃, a boiling duration of 30-60 minutes, and a stirring rate of 500-1500 rpm for the mixture.

8. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 2, characterized in that: In the second step, the thickness of the cuprous oxalate complex film is 60-100 nm.

9. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 8, characterized in that: In the second step, the thickness of the cuprous oxalate complex film is 80 nm.

10. The method for preparing antioxidant copper particles with oxalic acid compound-modified particle surface according to claim 2, characterized in that: In the third step, the centrifugation is performed at least twice.

Images