Metal Nanoparticle, Metal Nanoparticle Colloid, Method for Storing Metal Nanoparticle Colloid, and Metal Coating Film

[0126]Copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) of 15.7 g as an organic acid metal salt and dodecylamine (manufactured by Wako Pure Chemical Industries, Ltd.) of 148.1 g as an amine were mixed while stirring at 60° C. for 20 minutes. Next, the resulting mixture was cooled to 40° C., then reduction treatment was conducted by slowly adding 20 g of 20% sodium boron hydride aqueous solution as reducing agent thereto. Acetone of 200 g was added while stirring the solution which was subjected to the reduction treatment, allowed to stand for a while, then, precipitates composed of copper and organic substances were separated by filtration.

[0127]Toluene was added to the precipitates to dissolve again, and then the resulting solution was cooled to 10° C. Excess dodecylamine was coagulated and filtered out, thereby to give a liquid that fine particles of copper were dispersed in toluene. Next, by distilling toluene away from the copper fine particle-toluene

[0128]A 1 L-glass beaker was charged with copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) of 15.7 g as an organic acid metal salt and octylamine (manufactured by Wako Pure Chemical Industries, Ltd.) of 101.6 g as an amine, and mixed while stirring at 40° C. for 10 minutes. Next, the glass beaker was put into a constant-temperature water bath at 30° C., a solution of dimethylamine borane dissolved (reducing agent) was slowly added thereto over 0.5 hours for the liquid temperature to be around 40° C., subjected to a reduction treatment, formation of a metal nucleus and the growth were completed.

[0129]Acetone of 200 g was added to the solution which was subjected to the reduction treatment, allowed to stand for a while, then, precipitates composed of copper and organic substances were separated and recovered by filtration with a membrane filter having a pore diameter of 0.1 μm. Toluene was added to the recovered substance to dissolve again, the resulting s

[0134]A 1 L-beaker charged with octylamine (manufactured by Wako Pure Chemical Industries, Ltd.) of 148.1 g as an amine was put in a constant-temperature bath at 40° C. Next, copper acetate monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) of 15.7 g as an organic acid metal salt was added and sufficiently mixed while stirring for 20 minutes to prepare a homogeneous mixed solution. Subsequently, 20 g of a 20% sodium boron hydride aqueous solution as a reducing agent was slowly added thereto, and a reduction treatment was conducted.

[0135]Acetone of 200 g was added to the solution which was subjected to the reduction treatment, allowed to stand for a while, then precipitates composed of copper and organic substances were separated and recovered by filtration. Toluene was added to the recovered substance to dissolve again, the resulting solution was cooled to 10° C. or less then, filtered again, thereby to prepare a toluene dispersion liquid that impurities were reduced.

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