Metallic copper particles, and production method therefor

Abstract

Provided are: metallic copper particles exhibiting excellent low-temperature sintering properties at temperatures equal to or lower than 300° C.; and a production method therefor. In these metallic copper particles, metallic copper fine particles are adhered to the surfaces of large-diameter metallic copper particles. With regard to the metallic copper particles to be produced, copper oxide and hypophosphoric acid and/or a salt thereof are mixed and reduced, preferably in the presence of 1-500 mass % of gelatin and/or collagen peptide. The reduction reaction temperature is preferably in the range of 20-100° C. The produced metallic copper particles have a volume resistivity value when heated to a temperature of 300° C. under a nitrogen atmosphere of 1×10-2 Ω·cm or less.

1 . A metallic copper particle comprising a large diameter metallic copper particle and at least one fine metallic copper particle wherein the at least one fine metallic copper particle is adhered on a surface of the large diameter metallic copper particle. 
     
     
         2 . The metallic copper particle according to  claim 1 , wherein an aggregate of the fine metallic copper particles is adhered on the surface of the large diameter metallic copper particle. 
     
     
         3 . The metallic copper particle according to  claim 1 , further comprising a small metallic copper particle in a mixed state. 
     
     
         4 . The metallic copper particle according to  claim 1 , wherein a gelatin and/or a collagen peptide exist on at least one selected from the group consisting of the metallic copper particle, the large diameter metallic copper particle, and the at least one fine metallic copper particle. 
     
     
         5 . The metallic copper particle according to  claim 3 , wherein a gelatin and/or a collagen peptide exist on at least one selected from the group consisting of the metallic copper particle, the large diameter metallic copper particle, the at least one fine metallic copper particle e, and the small metallic copper particle. 
     
     
         6 . The metallic copper particle according to  claim 1 , wherein at least one selected from the group consisting of the metallic copper particle, the large diameter metallic copper particle, and the at least one fine metallic copper particle comprises an organic acid and/or a salt thereof. 
     
     
         7 . The metallic copper particle according to  claim 3 , wherein at least one selected from the group consisting of the metallic copper particle, the large diameter metallic copper particle, the at least one fine metallic copper particle, and the small metallic copper particle comprises an organic acid and/or a salt thereof. 
     
     
         8 . The metallic copper particle according to  claim 1 , having a specific surface area of 0.1 to 10 m2/g. 
     
     
         9 . A process for producing a metallic copper particle having a volume resistance value of 1×10-2 Ω·cm or less after heating the metallic copper particle at a temperature of 300° C. under a nitrogen atmosphere, the process comprising mixing a copper oxide and a hypophosphorous acid and/or a salt thereof in a solvent in the presence of a gelatin and/or a collagen peptide, thereby reducing the copper oxide. 
     
     
         10 . The process for producing a metallic copper particle according to  claim 9 , wherein the gelatin and/or the collagen peptide exist in 1 to 500 parts by mass with regard to 100 parts by mass of the metallic copper particle. 
     
     
         11 . The process for producing a metallic copper particle according to  claim 9 , wherein the reduction reaction is performed in a temperature range of 40 to 95° C. 
     
     
         12 . The process for producing a metallic copper particle according to  claim 9 , comprising mixing the copper oxide and the hypophosphorous acid and/or the salt thereof in the solvent in the presence of the gelatin and/or the collagen peptide, and an amine complexing agent, thereby reducing the copper oxide. 
     
     
         13 . The process for producing a metallic copper particle according to  claim 9 , comprising mixing the copper oxide and the hypophosphorous acid and/or the salt thereof in the solvent in the presence of the gelatin and/or the collagen peptide, and an organic acid, thereby reducing the copper oxide. 
     
     
         14 . The process for producing a metallic copper particle according to  claim 9 , comprising mixing the copper oxide and hypophosphorous acid and/or the salt thereof in the solvent in the presence of the gelatin and/or the collagen peptide, an amine complexing agent, and an organic acid, thereby reducing the copper oxide. 
     
     
         15 . The process for producing a metallic copper particle according to  claim 9 , wherein the reduction reaction is performed at a pH of 3 or lower. 
     
     
         16 . A metallic copper dispersion comprising the metallic copper particle according to  claim 8 .