Sumitomo Metal Mining Company, Ltd.

Murata Manufacturing Co., Ltd.

Junji Ishii

Masaya Yukinobu

Shingo Murakami

Hiroyuki Tanaka

Haruo Nishiyama

Toshiaki Terao

Yuji Watanabe

Tsutomu Tanimitsu

Takahiro Kamata

Yoshiyuki Kunifusa

Yuki Kumagai

Yoshiaki Matsumura

To provide a fine nickel powder for an internal electrode paste of an electronic component, the nickel powder obtained by a wet method and having high crystallinity, excellent sintering characteristics, and heat-shrinking characteristics. The nickel powder is obtained by precipitating nickel by a reduction reaction in a reaction solution including at least water-soluble nickel salt, salt of metal nobler than nickel, hydrazine as a reducing agent, and alkali metal hydroxide as a pH adjusting agent and water; the reaction solution is prepared by mixing a nickel salt solution including the water-soluble nickel salt and the salt of metal nobler than nickel with a mixed reducing agent solution including hydrazine and alkali metal hydroxide; and the hydrazine is additionally added to the reaction solution after a reduction reaction initiates in the reaction solution.

Nickel powder, method for manufacturing nickel powder, internal electrode paste using nickel powder, and electronic component

The purpose of the present invention is to provide a process for producing nickel powder capable of obtaining fine nickel powder in wet process, and also, capable of decreasing content of impurities by medicament (additive) used in crystallization of nickel powder which is reduction reaction. 1. A process for producing nickel powder, comprising a crystallization step for obtaining nickel crystal powder by reduction reaction in reaction solution in which at least water-soluble nickel salt, reducing agent, alkali hydroxide, if necessary metal salt of metal more noble than nickel, and water are mixed, and which is blended with sulfur-containing compound in advance, wherein the reducing agent is hydrazine (N2H4), the sulfur-containing compound is a compound having any of sulfur-containing functional group structure represented by &#x2014;SH, sulfur-containing functional group structure represented by &#x2014;S&#x2014;S&#x2014;, sulfur-containing functional group structure represented by &#x2014;O&#x2014;S(&#x2550;S)(&#x2550;O)&#x2014;O&#x2014; at least in molecule, and a ratio (A) of substance quantity of the sulfur-containing compound and nickel in the reaction solution ((molar number of the sulfur-containing compound/molar number of nickel)*10) [molar ppm], an effective multiplication factor (B) of the sulfur-containing functional group of the sulfur-containing compound [magnification] (&#x2014;SH: 1, &#x2014;S&#x2014;S&#x2014;: 2, &#x2014;O&#x2014;S(&#x2550;S)(&#x2550;O)&#x2014;O&#x2014;: 1), and a ratio (C) of substance quantity of the metal salt of metal more noble than nickel and nickel ((molar number of metal salt of metal more noble than nickel/molar number of nickel)*10) [molar ppm] is in a range of 0.1&#x2264;A*B&#x2264;0.75C+30 (0&#x2264;C&#x2264;100).

Process for producing nickel powder

A process for producing nickel powder capable of obtaining inexpensive, and also, high-performance nickel powder, even when using wet process. A process for producing nickel powder, including a crystallization step for obtaining nickel crystal powder by reductive reaction in reaction solution in which at least water-soluble nickel salt, metal salt of metal more noble than nickel, reducing agent, alkali hydroxide, amine compound, and water are mixed, wherein the reducing agent to be mixed in the crystallization step is hydrazine, the amine compound is autolysis inhibitor of hydrazine, and contains two or more primary amino groups in molecule, or contains one primary amino group and one or more secondary amino groups in molecule, and ratio of molar number of the amine compound with respect to molar number of nickel in the reaction solution is in a range of 0.01 mol % to 5 mol %.

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Ehime, Japan

Junji Ishii