Composite copper powder and preparation method and application thereof

Abstract

The invention relates to composite copper powder and a preparation method and application thereof. The composite copper powder comprises copper powder particles and an anti-oxidation layer attached to the surfaces of the copper powder particles. Wherein the copper powder particles are flaky copper powder particles and / or spherical copper powder particles, and the anti-oxidation layer is an organic matter monomolecular layer; the specific surface area of the composite copper powder is 0.5-5 m < 2 > / g, and the loss on ignition is 0.05-0.5%. The composite copper powder disclosed by the invention has excellent oxidation resistance and excellent conductivity.

Description

Technical Field

[0001] The invention relates to the field of conductive materials, and in particular to a composite copper powder and a preparation method and application thereof. Background Art

[0002] In recent years, conductive metal pastes have been widely used in semiconductors, electronics, energy, automobiles and other fields. At present, the conductive paste on the market mainly uses silver powder as the conductive filler because silver paste has excellent conductivity and oxidation resistance. However, the high price of silver and the migration phenomenon of silver have greatly hindered the widespread application and development of silver paste.

[0003] The electrical conductivity of copper is second only to silver, but copper powder is more easily oxidized than silver. Solving the oxidation resistance of copper has become a bottleneck in the development of copper paste. In the prior art, the organic surface adsorption method is usually used. However, due to the uneven surface of copper powder, a single adsorbent treatment produces many defects, resulting in the inability to sustain the oxidation resistance of copper powder. In addition, in order to achieve a good adsorption effect, the adsorbent concentration is usually high, and the adsorbent is adsorbed on the surface of copper powder in many layers, which hinders the charge conduction between copper powders. Summary of the invention

[0004] The purpose of the present invention is to provide a composite copper powder with a flat surface coating, so as to improve the contact and conductivity between the copper powders or between the copper powders and a substrate.

[0005] In order to achieve the above-mentioned object, the first aspect of the present invention provides a composite copper powder, which comprises copper powder particles and an anti-oxidation layer attached to the surface of the copper powder particles; wherein the copper powder particles are flaky copper powder particles and / or spherical copper powder particles, and the anti-oxidation layer is an organic monomolecular layer; the specific surface area of ​​the composite copper powder is 0.5 to 5 m 2 / g, and the loss on ignition is 0.05-0.5%.

[0006] The composite copper powder of the invention has a dense organic monomolecular anti-oxidation layer coated on the surface of the copper powder particles, thereby improving the anti-oxidation property of the copper powder and increasing the conductive efficiency of the copper powder.

[0007] The second part of the present invention provides a method for preparing a composite copper powder, which comprises: pre-treating flaky copper powder with ammonia or an organic amine solution to obtain a first material; or pre-treating spherical copper powder with an organic amine solution to obtain a second material; performing pickling treatment and adsorption treatment on the first material or the second material; wherein the adsorption treatment comprises using a group of adsorbent solutions with decreasing concentrations to sequentially adsorb the pickled material for n times, wherein 2≤n≤10; the pickling solution is an acid solution containing the adsorbent; the adsorbent in the adsorbent solution used for the adsorption treatment of the first material after the pickling treatment is selected from substituted or unsubstituted triazoles, wherein the substituted triazole has one or more substituents, and the substituents of the substituted triazole are independently selected from halogen, methyl, hydroxyl, and phenyl; the adsorbent in the adsorbent solution used for the adsorption treatment of the second material after the pickling treatment is selected from C4-C 20 Aliphatic thiols, C7-C 15 Aromatic thiols, C4-C 16 Heteroaryl thiols, C6-C 15 Arylthiophenol, mercapto-substituted imidazole ring compound and substituted or unsubstituted pyridine ring compound, the substituent of the substituted pyridine ring compound is selected from methyl, ethyl, propyl, butyl, isopropyl and tert-butyl.

[0008] In the preparation method of the present invention, the pretreated copper powder is firstly pickled using an acid solution added with an adsorbent, thereby achieving pre-adsorption of the adsorbent on the surface of the copper powder and avoiding the disordered arrangement of the adsorbent on the surface of the copper powder caused by the use of a high concentration adsorbent for adsorption; then, the pickled copper powder is adsorbed using an adsorbent solution with decreasing concentration, and in the adsorption process, an adsorption-desorption equilibrium based on a monomolecular layer of adsorbent is finally achieved to form a dense monomolecular antioxidant layer, thereby effectively protecting the copper powder particles.

[0009] The third part of the present invention provides a composite copper powder prepared according to the above-mentioned preparation method.

[0010] The fourth aspect of the present invention provides a conductive metal paste, which includes the aforementioned composite copper powder.

[0011] The fifth aspect of the present invention provides the application of the above conductive metal paste in photovoltaic cells.

[0012] Through the above technical scheme, the composite copper powder of the present invention comprises copper powder particles and an organic monomolecular anti-oxidation layer attached to the surface of the copper powder particles, and has excellent anti-oxidation performance and excellent electrical conductivity.

[0013] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0014] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0015] The first aspect of the present invention provides a composite copper powder, which comprises copper powder particles and an anti-oxidation layer attached to the surface of the copper powder particles; wherein the copper powder particles are flaky copper powder particles and / or spherical copper powder particles, and the anti-oxidation layer is an organic monomolecular layer; the specific surface area of ​​the composite copper powder is 0.5 to 5 m 2 / g, and the loss on ignition is 0.05-0.5%.

[0016] The composite copper powder of the invention has a dense organic monomolecular anti-oxidation layer coated on the surface of the copper powder particles, thereby improving the anti-oxidation property of the copper powder and increasing the conductive efficiency of the copper powder.

[0017] As a preferred embodiment of the present invention, the specific surface area of ​​the composite copper powder is 1 to 4 m 2 / g, and the loss on ignition is 0.1-0.25%.

[0018] In the present invention, based on the total mass of the composite copper powder, the weight of the copper powder particles can be 99.5-99.95wt%, preferably 99.75-99.95wt%; based on the total mass of the copper powder particles, the weight of the spherical copper powder particles can be 0-100wt%, preferably 30-70wt%;

[0019] The particle size of the flaky copper powder particles is 0.8 to 10 μm, preferably 1 to 5 μm; the particle size of the spherical copper powder particles is 20 to 1000 nm, preferably 20 to 300 nm.

[0020] According to the present invention, the organic single molecule can be selected from substituted or unsubstituted triazole, C4-C 20 Aliphatic thiols, C6-C 15 Aromatic thiols, C4-C 16 Heteroaryl thiols, C6-C 15 Arylthiophenol, mercapto-substituted imidazole ring compound, substituted or unsubstituted pyridine ring compound, wherein the substituted triazole has one or more substituents, the substituents of the substituted triazole are independently selected from halogen, cyano, methyl, ethyl, hydroxyl, phenyl, and the substituents of the substituted pyridine ring compound are selected from methyl, ethyl, propyl, butyl, isopropyl, and tert-butyl.

[0021] Preferably, the organic single molecule is selected from benzotriazole, 1-methylbenzotriazole, 4-hydroxybenzotriazole, 5-methylbenzotriazole, 5-fluorobenzotriazole, 1,2,4-triazole, 4-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, C4-C 16 Aliphatic thiols, C6-C 12 Aromatic thiols, C4-C 10 Heteroaryl thiols, C6-C 15 At least one of an arylthiophenol, a mercapto-substituted imidazole ring compound, and a substituted or unsubstituted pyridine ring compound.

[0022] Further preferably, the organic single molecule is selected from at least one of benzotriazole, 1-methylbenzotriazole, 4-hydroxybenzotriazole, 5-methylbenzotriazole, 5-fluorobenzotriazole, 1,2,4-triazole, 4-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, hexanethiol, heptylthiol, octylthiol, decanethiol, dodecylthiol, hexadecylthiol, p-methylthiophenol, m-methylthiophenol, p-ethylthiophenol, 2-pyridinethiol, 3-methylpyridine, 4-methylpyridine and 2-mercapto-1-methylimidazole.

[0023] The second part of the present invention provides a preparation method of composite copper powder, which comprises: pre-treating flaky copper powder with ammonia water or an organic amine solution to obtain a first material; or pre-treating spherical copper powder with an organic amine solution to obtain a second material; performing pickling treatment and adsorption treatment on the first material or the second material; wherein the adsorption treatment comprises using a group of adsorbent solutions with decreasing concentrations to sequentially adsorb the pickled material for n times, wherein 2≤n≤10; the pickling solution is an acid solution containing the adsorbent; the adsorbent in the adsorbent solution used for the adsorption treatment of the first material after the pickling treatment is selected from substituted or unsubstituted triazoles, wherein the substituted triazole has one or more substituents, and the substituents of the substituted triazole are independently selected from halogen, cyano, methyl, ethyl, hydroxyl, and phenyl; the adsorbent in the adsorbent solution used for the adsorption treatment of the second material after the pickling treatment is selected from C4-C 20 Aliphatic thiols, C7-C 15 Aromatic thiols, C4-C 16 Heteroarylthiols, substituted or unsubstituted C6-C 15 Arylthiophenol, C6-C 15 The thiol-substituted imidazole ring compound and the substituted or unsubstituted pyridine ring compound, the substituent of the substituted pyridine ring compound is selected from methyl, ethyl, propyl, butyl, isopropyl, tert-butyl, the substituted C6-C 15The substituent of the arylthiophenol is selected from methyl, ethyl, propyl, butyl, isopropyl and tert-butyl.

[0024] In the present invention, ammonia water or an organic amine solution is used to pretreat the copper powder, and while organic matter on the surface of the copper powder is removed, the corrosion of the copper powder by excessive alkali solution can be avoided; by firstly using an acid solution added with an adsorbent to perform an acid wash treatment on the pretreated copper powder, the pre-adsorption of the adsorbent on the surface of the copper powder is achieved, and the disordered arrangement of the adsorbent on the surface of the copper powder caused by the adsorption using a high-concentration adsorbent is avoided; then, the copper powder after the acid wash is adsorbed using an adsorbent solution with decreasing concentration, and the adsorption reaction process on the surface of the copper powder is refined. In the adsorption process, an adsorption-desorption equilibrium based on a monomolecular layer of adsorbent is finally achieved, and a dense monomolecular anti-oxidation layer is formed, thereby effectively protecting the copper powder particles.

[0025] The copper powder used in the present invention is selected from flaky copper powder and spherical copper powder. Among them, the flaky copper powder has a relatively flat surface structure. The present invention uses an adsorbent with an aromatic conjugated planar structure, which can better form a monomolecular layer protection on the surface of the flaky copper powder; the spherical copper powder has a smaller particle size. The present invention uses an adsorbent with a linear short-chain structure, and utilizes the hydrophilic and lipophilic properties of its chemical structure to achieve point anchoring and coating on the surface of the spherical copper powder to form a dense monomolecular layer. The present invention is aimed at the coating treatment of copper powders with different surface characteristics, which more effectively improves the oxidation resistance of the copper powder and improves the conductive efficiency.

[0026] In the present invention, the substituents of the substituted triazole are independently selected from fluorine, cyano, methyl, ethyl, hydroxyl, and phenyl. As a preferred embodiment of the present invention, the adsorbent in the adsorbent solution used for adsorbing the first material after the pickling treatment is selected from at least one of benzotriazole, 1-methylbenzotriazole, 4-hydroxybenzotriazole, 5-methylbenzotriazole, 5-fluorobenzotriazole, 1,2,4-triazole, 4-methyl-1,2,4-triazole and 3,5-dimethyl-1,2,4-triazole. The adsorbent in the adsorbent solution used for adsorbing the second material after the pickling treatment is selected from C4-C 16 Aliphatic thiols, C6-C 12 Aromatic thiols, C4-C 10 Heteroarylthiols, substituted or unsubstituted C6-C 15 Arylthiophenol, C6-C 15 The thiol-substituted imidazole ring compound and the substituted or unsubstituted pyridine ring compound, the substituent of the substituted pyridine ring compound is selected from methyl, ethyl, propyl, butyl, isopropyl, tert-butyl, the substituted C6-C 15The substituent of the arylthiophenol is selected from methyl, ethyl, propyl, butyl, isopropyl, and tert-butyl; as a preferred embodiment of the present invention, the adsorbent in the adsorbent solution used for adsorption treatment of the second material after pickling treatment is selected from hexyl mercaptan, heptyl mercaptan, octyl mercaptan, decanethiol, dodecyl mercaptan, hexadecyl mercaptan, p-methylthiophenol, m-methylthiophenol, p-ethylthiophenol, 2-pyridinethiol, 3-methylpyridine, 4-methylpyridine, and 2-mercapto-1-methylimidazole. The present invention is directed to the coating treatment of copper powders with different surface characteristics, so that the surface morphology of the copper powder and the adsorbent structure are more consistent, so that copper powders with different morphologies can obtain excellent oxidation resistance and conductivity.

[0027] In the present invention, an adsorbent solution with decreasing concentration is used to carry out adsorption treatment on the pickled copper powder, and the adsorption reaction process on the copper powder surface is refined, wherein the concentration of the adsorbent in the adsorbent solution used in the initial adsorption treatment can be 0.001-0.1 mol / L, preferably 0.01-0.1 mol / L; in a specific embodiment of the present invention, in the group of adsorbent solutions with decreasing concentration, starting from the second adsorption treatment, the concentration of the adsorbent in the adsorbent solution used in each adsorption treatment is successively reduced to 10%-80% of the concentration of the adsorbent in the adsorbent solution used in the previous adsorption treatment; preferably, the concentration of the adsorbent in the adsorbent solution used in each adsorption treatment is successively reduced to 50% of the concentration of the adsorbent in the adsorbent solution used in the previous adsorption treatment.

[0028] According to the present invention, a suitable adsorption treatment temperature is more conducive to achieving the adsorption-desorption equilibrium of the monolayer. The adsorption treatment temperature may be 25 to 100° C., and the time of a single adsorption treatment may be 0.1 to 10 h.

[0029] According to the present invention, the appropriate H in the pickling solution is + The concentration of H in the pickling solution is beneficial to the pre-adsorption process on the copper powder surface. + The concentration of H can be 0.01 to 2 mol / L, and the concentration of the adsorbent in the acid-washing solution can be H + Preferably, the H + The concentration of H is 0.01-1 mol / L, and the concentration of the adsorbent in the acid-washing solution is H + The concentration is 1% to 10%.

[0030] According to the present invention, the acid used in the pickling treatment can be selected from an inorganic acid or an organic acid having 1 to 30 carbon atoms; optionally, the acid is selected from at least one of hydrochloric acid, sulfuric acid, thiosulfuric acid, hypophosphorous acid, phosphorous acid, phosphoric acid, pyrophosphoric acid, boric acid, formic acid, acetic acid, propionic acid, n-butyric acid, n-valeric acid, n-hexanoic acid, glycolic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, acrylic acid, oleic acid, tartaric acid, fumaric acid, maleic acid, citric acid, benzoic acid, ascorbic acid and salicylic acid; preferably, the acid is selected from at least one of hydrochloric acid, sulfuric acid, thiosulfuric acid, phosphoric acid, pyrophosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, tartaric acid, fumaric acid, citric acid, benzoic acid and ascorbic acid.

[0031] According to the present invention, the pickling treatment may be performed 1 to 5 times, preferably 1 to 3 times; the temperature of the pickling treatment may be 0 to 80° C., and the time of a single pickling treatment may be 10 to 240 minutes.

[0032] In the present invention, ammonia water or organic amine solution is used to pre-treat the copper powder, thereby avoiding the corrosion of the copper powder by using strong alkali pre-treatment. + The concentration of the organic amine can be 0.01 to 5 mol / L, preferably 0.05 to 1 mol / L; the concentration of the organic amine in the organic amine solution can be 0.01 to 5 mol / L, preferably 0.05 to 1 mol / L.

[0033] According to the present invention, the organic amine can be selected from C1-C 20 Saturated alkylamines, C2-C 18 Alkenylamine, C6-C 24 Aromatic alkyl amines, C2-C 16 Preferably, the ionization equilibrium constant of the organic amine is less than 10.

[0034] In the present invention, the solvents in the organic amine solution, the adsorbent solution and the acid solution containing the adsorbent can be independently selected from at least one of water, methanol, ethanol, propanol, ethyl ether, isopropyl ether, methyl tert-butyl ether, tetrahydrofuran, acetone, methyl acetone, methyl formate, methyl acetate, ethyl acetate, butyl acetate, dichloromethane, toluene, petroleum ether, n-hexane, cyclohexane, n-heptane, ethylene glycol monomethyl ether, ethylene glycol propyl ether and ethylene glycol butyl ether.

[0035] According to the present invention, the pretreatment temperature may be 0 to 60° C., and the pretreatment time may be 30 to 180 min.

[0036] The third part of the present invention provides a composite copper powder prepared according to the aforementioned preparation method.

[0037] The fourth aspect of the present invention provides a conductive metal paste, which includes the aforementioned composite copper powder.

[0038] Optionally, the conductive metal paste includes spherical composite copper powder; based on the total mass of copper powder in the conductive metal paste, the weight of the spherical composite copper powder is 0 to 100 wt%, preferably 30 to 70 wt%.

[0039] The fifth aspect of the present invention provides the application of the aforementioned conductive metal paste in photovoltaic cells.

[0040] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0041] Example 1

[0042] Pretreatment was performed using an organic amine solution. 46.7 mL of ethylamine solution (mass dispersion of 70%) was measured and added to a 1 L volumetric flask, and water was added to make the volume 1 L to obtain a 0.5 mol / L ethylamine solution. 55 g of flaky copper powder with a particle size of D50 = 1 μm was weighed and added to a covered beaker containing 110 mL of 0.5 mol / L ethylamine solution, and stirred for 120 min at 40 ° C using a magnetic stirrer, and filtered under negative pressure to obtain pretreated copper powder.

[0043] Use an acid solution containing an adsorbent for pickling. Measure 12g of acetic acid, add it to a 1L volumetric flask, then add 200mL of ethanol, add 2.38g of benzotriazole, and then add ethanol to make the volume to 1L to obtain a 0.2mol / L acetic acid solution containing benzotriazole, wherein the concentration of benzotriazole is 0.02mol / L. Weigh 50g of pretreated copper powder, add it to a covered beaker containing 100mL of the above acetic acid solution, stir it with a magnetic stirrer at 45°C for 90min, filter under negative pressure, stir the copper powder again with 100mL of the above acetic acid solution at 45°C for 90min, filter under negative pressure, and obtain the pickled copper powder.

[0044] Adsorption treatment was performed using an adsorbent solution containing a certain concentration gradient. 0.9530 g of benzotriazole was measured and added to a 100 mL volumetric flask, and ethanol was added to make the volume to 100 mL to obtain a 0.08 mol / L benzotriazole solution. According to this method, 0.04 mol / L, 0.02 mol / L, and 0.01 mol / L benzotriazole solutions were obtained in turn. 45 g of pickled copper powder was weighed and added to a covered beaker containing 90 mL of benzotriazole solution, stirred at 50 ° C for 4 h using a magnetic stirrer, filtered under negative pressure, and then the copper powder was stirred at 50 ° C for 4 h using a magnetic stirrer with 0.04 mol / L, 0.02 mol / L, and 0.01 mol / L benzotriazole solutions, filtered under negative pressure, and the copper powder was dried at 50 ° C in a nitrogen-filled oven for 12 h to obtain a copper powder with an antioxidant layer.

[0045] Example 2

[0046] Pretreatment was performed using an organic amine solution. 9.02 g of ethylenediamine was measured and transferred to a 500 mL volumetric flask, and water was added to make the volume 500 mL to obtain a 0.3 mol / L ethylenediamine solution. 100 g of spherical copper powder with a particle size of D50 = 500 nm was weighed and added to a covered beaker containing 200 mL of ethylenediamine solution, stirred at 25 ° C using a magnetic stirrer for 60 min, and filtered under negative pressure to obtain pretreated copper powder.

[0047] Use an acid solution containing an adsorbent for pickling. Measure 14.7g of phosphoric acid and transfer it to a 500mL volumetric flask, then add 200mL of ethanol, then add 2.19g of octanethiol, add ethanol to make up to 500mL, and obtain a 0.3mol / L phosphoric acid solution containing octanethiol, wherein the concentration of octanethiol is 0.015mol / L. Weigh 90g of pretreated copper powder, add it to a covered beaker containing 180mL of the above phosphoric acid solution, stir it at 60°C with a magnetic stirrer for 150min, and filter under negative pressure to obtain the pickled copper powder.

[0048] Adsorption treatment was performed using an adsorbent solution containing a certain concentration gradient. 1.46 g of octanethiol was measured and added to a 100 mL volumetric flask, and ethanol was added to make the volume to 100 mL to obtain a 0.1 mol / L octanethiol solution. According to this method, 0.05 mol / L and 0.025 mol / L octanethiol solutions were obtained in turn. 50 g of pickled copper powder was weighed and added to a covered beaker containing 100 mL of octanethiol solution, stirred at 25 ° C for 12 h using a magnetic stirrer, and filtered under negative pressure. According to this method, the solvent was replaced with n-hexane to obtain 0.0125 mol / L and 0.0063 mol / L octanethiol solutions, and then the copper powder was stirred with the above octanethiol solution at 25 ° C for 2 h using a magnetic stirrer, filtered under negative pressure, and the copper powder was dried at 50 ° C in a nitrogen-filled oven for 12 h to obtain a copper powder with an antioxidant layer.

[0049] Embodiments 3 to 6

[0050] The specific methods of Examples 3 to 6 are the same as those of Example 1, wherein the parameters and reagents of each step are shown in Table 1.

[0051] Table 1 shows the operating parameters and reagent selections of each step of Examples 1 to 6, wherein "Temperature / Time" represents the temperature and time of a single operation, and "Decrease Percentage %" represents that in a group of adsorbent solutions with decreasing concentrations, starting from the second adsorption treatment, the concentration of the adsorbent in the adsorbent solution used in each adsorption treatment is successively reduced to the ratio of the concentration of the adsorbent in the adsorbent solution used in the previous adsorption treatment.

[0052] Table 1

[0053]

[0054] Comparative Example 1

[0055] Prepare a 0.08 mol / L benzotriazole ethanol solution, add 50 g of flaky copper powder with a particle size D50 = 1 μm into a covered beaker containing 100 mL of the above benzotriazole solution, stir with a magnetic stirrer at 50°C for 4 h, filter under negative pressure, and dry the copper powder in a nitrogen-filled oven at 50°C for 12 h to obtain the copper powder treated in Comparative Example 1.

[0056] Comparative Example 2

[0057] Prepare a 0.1 mol / L octanethiol ethanol solution, add 50 g of spherical copper powder with a particle size D50 = 500 nm into a covered beaker containing 100 mL of the above octanethiol solution, stir with a magnetic stirrer at 25 ° C for 12 h, filter under negative pressure, and dry the copper powder in a nitrogen-filled oven at 50 ° C for 12 h to obtain the copper powder treated in Comparative Example 2.

[0058] Comparative Example 3

[0059] The pretreatment step and pickling step of this comparative example are the same as those of Example 1, except that the adsorption treatment is performed 4 times using the same concentration of adsorbent solution. The specific adsorption treatment step includes: measuring 0.9530g of benzotriazole, adding it to a 100mL volumetric flask, adding ethanol to make the volume to 100mL, and obtaining a 0.08mol / L benzotriazole solution. Weigh 45g of the pickled copper powder, add it to a covered beaker containing 90mL of benzotriazole solution, stir it at 50°C with a magnetic stirrer for 4h, filter under negative pressure, repeat the above adsorption step 3 times, and dry the obtained copper powder at 50°C in a nitrogen-filled oven for 12h to obtain the copper powder treated in Comparative Example 3.

[0060] Comparative Example 4

[0061] The pretreatment step and pickling step of this comparative example are the same as those of Example 1, except that the adsorption treatment is performed 4 times using the same concentration of adsorbent solution. The specific adsorption treatment step includes: measuring 0.1191g of benzotriazole, adding it to a 100mL volumetric flask, adding ethanol to make up to 100mL, and obtaining a 0.01mol / L benzotriazole solution. Weigh 45g of the pickled copper powder, add it to a covered beaker containing 90mL of benzotriazole solution, stir it at 50°C with a magnetic stirrer for 4h, filter under negative pressure, repeat the above adsorption step 3 times, and dry the obtained copper powder at 50°C in a nitrogen-filled oven for 12h to obtain the copper powder treated in Comparative Example 3.

[0062] Comparative Example 5

[0063] Pretreatment was performed using an organic amine solution. 46.7 mL of ethylamine solution (mass dispersion of 70%) was measured and added to a 1 L volumetric flask, and water was added to make the volume 1 L to obtain a 0.5 mol / L ethylamine solution. 55 g of flaky copper powder with a particle size of D50 = 1 μm was weighed and added to a covered beaker containing 110 mL of 0.5 mol / L ethylamine solution, and stirred for 120 min at 40 ° C using a magnetic stirrer, and filtered under negative pressure to obtain pretreated copper powder.

[0064] Adsorption treatment was performed using an adsorbent solution containing a certain concentration gradient. 0.9530 g of benzotriazole was measured, added to a 100 mL volumetric flask, and ethanol was added to 100 mL to obtain a 0.08 mol / L benzotriazole solution, and 0.04 mol / L, 0.02 mol / L, and 0.01 mol / L benzotriazole solutions were obtained in sequence according to this method. 45 g of pretreated copper powder was weighed, added to a covered beaker containing 90 mL of benzotriazole solution, stirred at 50 ° C for 4 h using a magnetic stirrer, filtered under negative pressure, and then the copper powder was stirred at 50 ° C for 4 h using a magnetic stirrer with 0.04 mol / L, 0.02 mol / L, and 0.01 mol / L benzotriazole solutions, filtered under negative pressure, and the copper powder was dried at 50 ° C for 12 h in a nitrogen-filled oven to obtain the copper powder prepared in Comparative Example 5.

[0065] Comparative Example 6

[0066] Use an acid solution containing an adsorbent for pickling. Measure 12g of acetic acid, add it to a 1L volumetric flask, then add 200mL of ethanol, add 2.38g of benzotriazole, and then add ethanol to make the volume to 1L to obtain a 0.2mol / L acetic acid solution containing benzotriazole, wherein the benzotriazole concentration is 0.02mol / L. Weigh 50g of flaky copper powder with a particle size of D50=1μm, add it to a covered beaker containing 100mL of the above acetic acid solution, stir it at 45°C with a magnetic stirrer for 90min, filter it under negative pressure, stir the copper powder again with 100mL of the above acetic acid solution at 45°C for 90min, filter it under negative pressure, and obtain the pickled copper powder.

[0067] Adsorption treatment was performed using an adsorbent solution containing a certain concentration gradient. 0.9530 g of benzotriazole was measured and added to a 100 mL volumetric flask, and ethanol was added to make the volume to 100 mL to obtain a 0.08 mol / L benzotriazole solution. According to this method, 0.04 mol / L, 0.02 mol / L, and 0.01 mol / L benzotriazole solutions were obtained in turn. 45 g of pickled copper powder was weighed and added to a covered beaker containing 90 mL of benzotriazole solution, stirred at 50 ° C for 4 h using a magnetic stirrer, filtered under negative pressure, and then the copper powder was stirred at 50 ° C for 4 h using a magnetic stirrer with 0.04 mol / L, 0.02 mol / L, and 0.01 mol / L benzotriazole solutions, filtered under negative pressure, and the copper powder was dried at 50 ° C in a nitrogen-filled oven for 12 h to obtain a copper powder with an antioxidant layer.

[0068] Test Example 1

[0069] 10 g of copper powder obtained in Examples 1 to 6 and Comparative Examples 1 to 6 were respectively immersed in 100 mL of 0.25 mol / L hydrochloric acid and 0.25 mol / L sodium hydroxide solution for 24 h (25° C.), filtered under negative pressure, and the copper powder was rinsed with deionized water until the pH of the elution was neutral. The copper powder was then rinsed with anhydrous ethanol to remove moisture, and baked in a vacuum oven at 50° C. for 12 h (vacuum degree <-0.095 MPa). The antioxidant degree was calculated by formula (I) as an indicator of antioxidant activity. The specific results are shown in Table 2.

[0070] Formula (I):

[0071]

[0072] Where: μ—antioxidant degree, %;

[0073] ω0—mass before immersion treatment, g;

[0074] ω1—mass after immersion treatment, g;

[0075] Table 2

[0076]

[0077]

[0078] It can be seen from Table 2 that the antioxidant copper powder prepared by the method of the present invention has achieved excellent antioxidant effect.

[0079] Test Example 2

[0080] Conductive copper slurries were prepared using the copper powders obtained in Examples 1 to 6 and Comparative Examples 1 to 6 under the same formula and process, and their sheet resistances were tested and compared.

[0081] The formula of the conductive copper slurry is shown in Table 3 below. It should be pointed out that in order to better evaluate the advantages of the present invention, the copper powder in the conductive copper slurry formula can be spherical copper powder, flake copper powder or a mixture of the two (the proportion of spherical copper powder is 0 to 100%, preferably 30 to 70%).

[0082] Table 3

[0083] Components Quantity / g Components Quantity / g Copper powder 85 Polyamide wax RC-100 0.5 Bisphenol F epoxy resin 170 5 Terpineol 2 Blocked isocyanate DXTB-65 4 Diethylene glycol butyl ether acetate 3 Accelerator MY-24 0.5 / /

[0084] The conductive copper paste prepared according to the above formula was printed on a glass substrate using a screen printer and cured in a nitrogen oven at 180°C for 30 min. The screen printing process was adjusted to make the sample thickness 20 μm, and its sheet resistance was tested. The test results are shown in Table 4.

[0085] Table 3

[0086] Group Copper powder Spherical copper powder percentage Sheet resistance mΩ / □ Group 1 Example 1+Example 2 38 4.02 Group 2 Example 4+Example 5 50 4.83 Group 3 Example 1+Example 6 63 3.87 Group 4 Example 3+Example 5 65 6.14 Group 5 Example 1 0 7.31 Group 6 Example 2 100 10.78 Group 7 Comparative Example 1 0 5970 Group 8 Comparative Example 2 100 10300 Group 9 Comparative Example 1+Comparative Example 2 38 4280 Group 10 Comparative Example 1+Comparative Example 2 63 7150 Group 11 Comparative Example 3 0 103.5 Group 12 Comparative Example 4 0 185.8 Group 13 Comparative Example 5 0 873 Group 14 Comparative Example 6 0 1252

[0087] It can be seen from Table 4 that under the same conductive copper slurry formula, the antioxidant copper powder prepared by the method of the present invention has better conductivity than the copper powder prepared by the conventional treatment method. In particular, compared with the over-adsorbed copper powder prepared in Comparative Example 4, the antioxidant copper powder prepared by the method of the present invention has excellent conductivity.

[0088] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0089] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0090] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A composite copper powder, characterized in that: The composite copper powder comprises copper powder particles and an anti-oxidation layer attached to the surface of the copper powder particles; wherein the copper powder particles are flaky copper powder particles and / or spherical copper powder particles, and the anti-oxidation layer is an organic monomolecular layer; the specific surface area of ​​the composite copper powder is 0.5 to 5 m 2 / g, and the loss on ignition is 0.05-0.5%.

2. The composite copper powder according to claim 1, characterized in that The specific surface area of ​​the composite copper powder is 1 to 4 m 2 / g, and the loss on ignition is 0.1-0.25%.

3. The composite copper powder according to claim 1, characterized in that Based on the total mass of the composite copper powder, the weight percentage of the copper powder particles is 99.5-99.95wt%, preferably 99.75-99.95wt%; Based on the total mass of the copper powder particles, the weight of the spherical copper powder particles is 0 to 100 wt%, preferably 30 to 70 wt%; The particle size of the flaky copper powder particles is 0.8 to 10 μm, preferably 1 to 5 μm; the particle size of the spherical copper powder particles is 20 to 1000 nm, preferably 20 to 300 nm.

4. The composite copper powder according to claim 1, characterized in that The organic single molecule is selected from substituted or unsubstituted triazole, C4-C 20 Aliphatic thiols, C6-C 15 Aromatic thiols, C4-C 16 Heteroaryl thiols, C6-C 15 Arylthiophenol, C6-C 15 A thiol-substituted imidazole ring compound or a substituted or unsubstituted pyridine ring compound, wherein the substituted triazole has one or more substituents, and the substituents of the substituted triazole are independently selected from halogen, cyano, methyl, ethyl, hydroxyl, and phenyl, and the substituents of the substituted pyridine ring compound are selected from methyl, ethyl, propyl, butyl, isopropyl, and tert-butyl; Preferably, the organic single molecule is selected from benzotriazole, 1-methylbenzotriazole, 4-hydroxybenzotriazole, 5-methylbenzotriazole, 5-fluorobenzotriazole, 1,2,4-triazole, 4-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, C4-C 16 Aliphatic thiols, C6-C 12 Aromatic thiols, C4-C 10 Heteroaryl thiols, C6-C 15 At least one of an arylthiophenol, a mercapto-substituted imidazole ring compound and a substituted or unsubstituted pyridine ring compound, wherein the substituent of the substituted pyridine ring compound is selected from methyl, ethyl, propyl, butyl, isopropyl and tert-butyl; Further preferably, the organic single molecule is selected from at least one of benzotriazole, 1-methylbenzotriazole, 4-hydroxybenzotriazole, 5-methylbenzotriazole, 5-fluorobenzotriazole, 1,2,4-triazole, 4-methyl-1,2,4-triazole, 3,5-dimethyl-1,2,4-triazole, hexanethiol, heptylthiol, octylthiol, decanethiol, dodecylthiol, hexadecylthiol, p-methylthiophenol, m-methylthiophenol, p-ethylthiophenol, 2-pyridinethiol, 3-methylpyridine, 4-methylpyridine and 2-mercapto-1-methylimidazole.

5. A method for preparing a composite copper powder, characterized in that: The method includes: Pre-treating the flaky copper powder with ammonia water or an organic amine solution to obtain a first material; or pre-treating the spherical copper powder with an organic amine solution to obtain a second material; Performing pickling treatment and adsorption treatment on the first material or the second material; The adsorption treatment includes using a group of adsorbent solutions with decreasing concentrations to sequentially adsorb the material after the pickling treatment for n times, wherein 2≤n≤10; the solution for the pickling treatment is an acid solution containing the adsorbent; The adsorbent in the adsorbent solution used for adsorption treatment of the first material after pickling treatment is selected from substituted or unsubstituted triazoles, wherein the substituted triazole has one or more substituents, and the substituents of the substituted triazole are independently selected from halogen, cyano, methyl, ethyl, hydroxyl, and phenyl; the adsorbent in the adsorbent solution used for adsorption treatment of the second material after pickling treatment is selected from C4-C 20 Aliphatic thiols, C6-C 15 Aromatic thiols, C4-C 16 Heteroarylthiols, substituted or unsubstituted C6-C 15 Arylthiophenol, thiol-substituted imidazole ring compound and substituted or unsubstituted pyridine ring compound, the substituent of the substituted pyridine ring compound is selected from methyl, ethyl, substituted C6-C 15 The substituent of the arylthiophenol is selected from methyl, ethyl, propyl, butyl, isopropyl and tert-butyl.

6. The preparation method according to claim 5, characterized in that: The substituents of the substituted triazole are independently selected from fluorine, cyano, methyl, ethyl, hydroxyl, and phenyl; preferably, the adsorbent in the adsorbent solution used for adsorption treatment of the first material after the pickling treatment is selected from at least one of benzotriazole, 1-methylbenzotriazole, 4-hydroxybenzotriazole, 5-methylbenzotriazole, 5-fluorobenzotriazole, 1,2,4-triazole, 4-methyl-1,2,4-triazole and 3,5-dimethyl-1,2,4-triazole; The adsorbent in the adsorbent solution used for adsorption treatment of the second material after pickling treatment is selected from C4-C 16 Aliphatic thiols, C6-C 12 Aromatic thiols, C4-C 10 Heteroarylthiols, substituted or unsubstituted C6-C 15 Arylthiophenol, thiol-substituted imidazole ring compound and substituted or unsubstituted pyridine ring compound, the substituent of the substituted pyridine ring compound is selected from methyl, ethyl, substituted C6-C 15 The substituent of the aromatic thiophenol is selected from methyl and ethyl; preferably, the adsorbent in the adsorbent solution used for adsorption treatment of the second material after the acid washing treatment is selected from hexyl mercaptan, heptyl mercaptan, octyl mercaptan, decanyl mercaptan, dodecyl mercaptan, hexadecyl mercaptan, p-methyl thiophenol, m-methyl thiophenol, p-ethyl thiophenol, 2-pyridinethiol, 3-methylpyridine, 4-methylpyridine, and 2-mercapto-1-methylimidazole.

7. The preparation method according to claim 5, characterized in that: The concentration of the adsorbent in the adsorbent solution used in the initial adsorption treatment is 0.001 to 0.1 mol / L, preferably 0.01 to 0.1 mol / L; In the group of adsorbent solutions with decreasing concentrations, starting from the second adsorption treatment, the concentration of the adsorbent in the adsorbent solution used in each adsorption treatment decreases successively to 10% to 80% of the concentration of the adsorbent in the adsorbent solution used in the previous adsorption treatment; preferably, the concentration of the adsorbent in the adsorbent solution used in each adsorption treatment decreases successively to 50% of the concentration of the adsorbent in the adsorbent solution used in the previous adsorption treatment.

8. The preparation method according to claim 5, characterized in that: The temperature of the adsorption treatment is 25-100° C., and the time of a single adsorption treatment is 0.1-10 hours.

9. The preparation method according to claim 5, characterized in that: The acid-washing solution contains H + The concentration of H is 0.01-2 mol / L, and the concentration of the adsorbent in the acid-washing solution is H + Preferably, the H + The concentration of H is 0.01-1 mol / L, and the concentration of the adsorbent in the acid-washing solution is H + The concentration is 1% to 10%.

10. The preparation method according to claim 5 or 9, characterized in that: The acid used in the pickling treatment is selected from inorganic acids and C1-C 30 of an organic acid; optionally, the acid is selected from at least one of hydrochloric acid, sulfuric acid, thiosulfuric acid, hypophosphorous acid, phosphorous acid, phosphoric acid, pyrophosphoric acid, boric acid, formic acid, acetic acid, propionic acid, n-butyric acid, n-valeric acid, n-hexanoic acid, glycolic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, acrylic acid, oleic acid, tartaric acid, fumaric acid, maleic acid, citric acid, benzoic acid, ascorbic acid and salicylic acid; preferably, the acid is selected from at least one of hydrochloric acid, sulfuric acid, thiosulfuric acid, phosphoric acid, pyrophosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, tartaric acid, fumaric acid, citric acid, benzoic acid and ascorbic acid.

11. The preparation method according to claim 5 or 9, characterized in that: The pickling treatment is performed 1 to 5 times, preferably 1 to 3 times; The temperature of the pickling treatment is 0 to 80° C., and the time of a single pickling treatment is 10 to 240 minutes.

12. The preparation method according to claim 5, characterized in that: NH4 in ammonia water + The concentration of the organic amine is 0.01 to 5 mol / L, preferably 0.05 to 1 mol / L; the concentration of the organic amine in the organic amine solution is 0.01 to 5 mol / L, preferably 0.05 to 1 mol / L.

13. The preparation method according to claim 5 or 12, characterized in that: The organic amine is selected from C1-C 20 Saturated alkylamines, C2-C 18 Alkenylamine, C6-C 24 Aromatic alkyl amines, C2-C 16 Preferably, the ionization equilibrium constant of the organic amine is less than 10.

14. The preparation method according to claim 5, characterized in that: The solvents in the organic amine solution, the adsorbent solution and the acid solution containing the adsorbent are each independently selected from at least one of water, methanol, ethanol, propanol, ethyl ether, isopropyl ether, methyl tert-butyl ether, tetrahydrofuran, acetone, methyl acetone, methyl formate, methyl acetate, ethyl acetate, butyl acetate, dichloromethane, toluene, petroleum ether, n-hexane, cyclohexane, n-heptane, ethylene glycol monomethyl ether, ethylene glycol propyl ether and ethylene glycol butyl ether.

15. The preparation method according to claim 5, characterized in that: The pretreatment temperature is 0-60° C., and the pretreatment time is 30-180 min.

16. Composite copper powder prepared by the preparation method according to any one of claims 5 to 15.

17. A conductive metal paste, characterized in that: The conductive metal paste comprises the composite copper powder according to any one of claims 1 to 4 and claim 16.

18. The conductive metal paste according to claim 17, characterized in that: The conductive metal paste includes spherical composite copper powder; based on the total mass of the copper powder in the conductive metal paste, the weight of the spherical composite copper powder is 0 to 100 wt%, preferably 30 to 70 wt%.

19. Use of the conductive metal paste according to claim 17 or 18 in photovoltaic cells.

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