JP6846969B2 - Silver-coated nickel powder and its manufacturing method - Google Patents
Silver-coated nickel powder and its manufacturing method Download PDFInfo
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- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 title claims description 248
- 229910052709 silver Inorganic materials 0.000 title claims description 204
- 239000004332 silver Substances 0.000 title claims description 204
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 title claims description 203
- 238000004519 manufacturing process Methods 0.000 title claims description 18
- 239000002245 particle Substances 0.000 claims description 69
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 63
- 239000001301 oxygen Substances 0.000 claims description 63
- 229910052760 oxygen Inorganic materials 0.000 claims description 63
- 238000000034 method Methods 0.000 claims description 36
- 239000011248 coating agent Substances 0.000 claims description 34
- 238000000576 coating method Methods 0.000 claims description 34
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 27
- 239000001257 hydrogen Substances 0.000 claims description 27
- 229910052739 hydrogen Inorganic materials 0.000 claims description 27
- 229910052759 nickel Inorganic materials 0.000 claims description 21
- 239000012298 atmosphere Substances 0.000 claims description 14
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 7
- 239000000460 chlorine Substances 0.000 claims description 7
- 229910052801 chlorine Inorganic materials 0.000 claims description 7
- 239000000243 solution Substances 0.000 description 45
- 230000001186 cumulative effect Effects 0.000 description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 31
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 24
- 229910052799 carbon Inorganic materials 0.000 description 24
- 239000000843 powder Substances 0.000 description 18
- 238000009826 distribution Methods 0.000 description 17
- -1 silver ions Chemical class 0.000 description 11
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 10
- 239000001099 ammonium carbonate Substances 0.000 description 10
- 235000012501 ammonium carbonate Nutrition 0.000 description 10
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 10
- 229940100890 silver compound Drugs 0.000 description 9
- 150000003379 silver compounds Chemical class 0.000 description 9
- 239000002904 solvent Substances 0.000 description 8
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 6
- 239000002738 chelating agent Substances 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 239000003960 organic solvent Substances 0.000 description 5
- 229910001961 silver nitrate Inorganic materials 0.000 description 5
- 239000006185 dispersion Substances 0.000 description 4
- 238000005259 measurement Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000001376 precipitating effect Effects 0.000 description 3
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 description 3
- 238000006467 substitution reaction Methods 0.000 description 3
- 238000009692 water atomization Methods 0.000 description 3
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 2
- 241000892865 Heros Species 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910001453 nickel ion Inorganic materials 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000010791 quenching Methods 0.000 description 2
- 150000003378 silver Chemical class 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- IMNIMPAHZVJRPE-UHFFFAOYSA-N triethylenediamine Chemical compound C1CN2CCN1CC2 IMNIMPAHZVJRPE-UHFFFAOYSA-N 0.000 description 2
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000005056 compaction Methods 0.000 description 1
- 239000007771 core particle Substances 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000009689 gas atomisation Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- NBZBKCUXIYYUSX-UHFFFAOYSA-N iminodiacetic acid Chemical compound OC(=O)CNCC(O)=O NBZBKCUXIYYUSX-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 150000002815 nickel Chemical class 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 235000021110 pickles Nutrition 0.000 description 1
- 239000010970 precious metal Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- HKZLPVFGJNLROG-UHFFFAOYSA-M silver monochloride Chemical compound [Cl-].[Ag+] HKZLPVFGJNLROG-UHFFFAOYSA-M 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 229910021642 ultra pure water Inorganic materials 0.000 description 1
- 239000012498 ultrapure water Substances 0.000 description 1
Description
本発明は、銀被覆ニッケル粉末およびその製造方法に関し、特に、導電性ペーストなどに使用する銀被覆ニッケル粉末およびその製造方法に関する。 The present invention relates to a silver-coated nickel powder and a method for producing the same, and more particularly to a silver-coated nickel powder used for a conductive paste or the like and a method for producing the same.
従来、電子部品の電極や配線を形成するために、銀粉などの導電性の金属粉末に溶剤、樹脂、分散剤などを配合して作製した導電性ペーストが使用されている。 Conventionally, in order to form electrodes and wiring of electronic parts, a conductive paste prepared by blending a solvent, a resin, a dispersant or the like with a conductive metal powder such as silver powder has been used.
しかし、銀粉は、体積抵抗率が極めて小さく、良好な導電性物質であるが、貴金属の粉末であるため、コストが高くなる。 However, although silver powder has an extremely low volume resistivity and is a good conductive substance, it is a precious metal powder, so that the cost is high.
そのため、導電性ペーストなどに使用する導電性の金属粉末として、比較的安価なニッケル粉末の表面を銀で被覆した銀被覆ニッケル粉末を使用することが検討されている。 Therefore, as a conductive metal powder used for a conductive paste or the like, it has been studied to use a silver-coated nickel powder in which the surface of a relatively inexpensive nickel powder is coated with silver.
このような銀被覆ニッケル粉末として、銀とニッケルからなり、銀とニッケルの合計１００質量部に対して、銀を６〜１５質量部を含み、圧力５．６ＭＰａにおける粉体抵抗値が０．１〜０．５Ω・ｍｍである銀被覆ニッケル粉末（例えば、特許文献１参照）や、ニッケルを含むコア粒子の表面に銀が被覆された銀コートニッケル粒子において、銀コートニッケル粒子の表面の全域にわたって、多数の凸部が形成されて表面が凹凸形状になり、平面視における凸部の大きさが０．０５〜１μｍであり、銀コートニッケル粒子中の銀の被覆率が５０％以上である銀コートニッケル粒子（例えば、特許文献２参照）などが提案されている。 Such silver-coated nickel powder is composed of silver and nickel, contains 6 to 15 parts by mass of silver with respect to 100 parts by mass of silver and nickel in total, and has a powder resistance value of 0.1 at a pressure of 5.6 MPa. In silver-coated nickel powder having a thickness of ~ 0.5 Ω · mm (see, for example, Patent Document 1) or silver-coated nickel particles in which the surface of core particles containing nickel is coated with silver, the entire surface of the silver-coated nickel particles is covered. , A large number of convex portions are formed to form an uneven surface, the size of the convex portions in a plan view is 0.05 to 1 μm, and the coverage of silver in the silver-coated nickel particles is 50% or more. Coated nickel particles (see, for example, Patent Document 2) have been proposed.
しかし、特許文献１の銀被覆ニッケル粉末や特許文献２の銀コートニッケル粒子は、導電性が十分ではないという問題がある。 However, the silver-coated nickel powder of Patent Document 1 and the silver-coated nickel particles of Patent Document 2 have a problem of insufficient conductivity.
したがって、本発明は、このような従来の問題点に鑑み、導電性が良好で安価な銀被覆ニッケル粉末およびその製造方法を提供することを目的とする。 Therefore, in view of such conventional problems, an object of the present invention is to provide an inexpensive silver-coated nickel powder having good conductivity and a method for producing the same.
本発明者らは、上記課題を解決するために鋭意研究した結果、ニッケル粉末を水素雰囲気中で還元することによってニッケル粉末中の酸素含有量を低減させた後、この酸素含有量を低減させたニッケル粉末の表面を銀含有層により被覆することにより、導電性が良好で安価な銀被覆ニッケル粉末を製造することができることを見出し、本発明を完成するに至った。 As a result of diligent research to solve the above problems, the present inventors reduced the oxygen content in the nickel powder by reducing the nickel powder in a hydrogen atmosphere, and then reduced the oxygen content. By coating the surface of the nickel powder with a silver-containing layer, it has been found that an inexpensive silver-coated nickel powder having good conductivity can be produced, and the present invention has been completed.
すなわち、本発明による被覆ニッケル粉末の製造方法は、ニッケル粉末を水素雰囲気中で還元することによってニッケル粉末中の酸素含有量を低減させた後、この酸素含有量を低減させたニッケル粉末の表面を銀含有層により被覆することを特徴とする。 That is, in the method for producing a coated nickel powder according to the present invention, the oxygen content in the nickel powder is reduced by reducing the nickel powder in a hydrogen atmosphere, and then the surface of the nickel powder having the reduced oxygen content is treated. It is characterized by being coated with a silver-containing layer.
この銀被覆ニッケル粉末の製造方法において、ニッケル粉末中の酸素含有量を０．８質量％以下に低減させるのが好ましく、ニッケル粉末のＢＥＴ比表面積に対する酸素含有量の比が２．０質量％・ｇ／ｍ２以下になるようにニッケル粉末中の酸素含有量を低減させるのが好ましい。ニッケル粉末は、アトマイズ法により製造するのが好ましく、平均粒径が０．１〜１５μｍであるのが好ましい。銀含有層は、被覆量が３〜５０質量％であるのが好ましく、銀または銀化合物からなる層であるのが好ましい。 In this method for producing silver-coated nickel powder, it is preferable to reduce the oxygen content in the nickel powder to 0.8% by mass or less, and the ratio of the oxygen content to the BET specific surface area of the nickel powder is 2.0% by mass. It is preferable to reduce the oxygen content in the nickel powder so that it is g / m 2 or less. The nickel powder is preferably produced by an atomizing method, and the average particle size is preferably 0.1 to 15 μm. The silver-containing layer preferably has a coating amount of 3 to 50% by mass, and is preferably a layer made of silver or a silver compound.
また、本発明による銀被覆ニッケル粉末は、表面が３〜５０質量％の銀含有層により被覆され、酸素含有量が０．７質量％以下であり、色差（Ｌ＊）が４８以上であることを特徴とする。 Further, the silver-coated nickel powder according to the present invention has a surface coated with a silver-containing layer of 3 to 50% by mass, an oxygen content of 0.7% by mass or less, and a color difference (L * ) of 48 or more. It is characterized by.
この銀被覆ニッケル粉末において、銀被覆ニッケル粉末のＢＥＴ比表面積に対する酸素含有量の比が１．０質量％・ｇ／ｍ２以下であるのが好ましく、銀被覆ニッケル粉末に５．６ＭＰａの圧力を加えたときの体積抵抗率が０．１〜１０ｍΩ・ｃｍであるのが好ましい。また、銀被覆ニッケル粉末の色差（Ｌ＊）が５０〜８０であるのが好ましい。また、銀被覆ニッケル粉末の平均粒径が０．１〜１５μｍであるのが好ましく、銀被覆ニッケル粉末のＢＥＴ比表面積が０．１〜５ｍ２／ｇであるのが好ましい。また、銀被覆ニッケル粉末中の塩素含有量が１００ｐｐｍ未満であるのが好ましく、銀含有層が銀または銀化合物からなる層であるのが好ましい。 In this silver-coated nickel powder, the ratio of the oxygen content to the BET specific surface area of the silver-coated nickel powder is preferably 1.0% by mass · g / m 2 or less, and a pressure of 5.6 MPa is applied to the silver-coated nickel powder. The volume resistivity when added is preferably 0.1 to 10 mΩ · cm. Further, the color difference (L * ) of the silver-coated nickel powder is preferably 50 to 80. The average particle size of the silver-coated nickel powder is preferably 0.1 to 15 μm, and the BET specific surface area of the silver-coated nickel powder is preferably 0.1 to 5 m 2 / g. Further, the chlorine content in the silver-coated nickel powder is preferably less than 100 ppm, and the silver-containing layer is preferably a layer made of silver or a silver compound.
なお、本明細書中において、「平均粒径」とは、（ヘロス法によって）レーザー回折式粒度分布測定装置により測定した体積基準の累積５０％粒子径（Ｄ５０径）をいう。 In this specification, the "average particle diameter" refers to a (by Heroes method) 50% cumulative particle diameter on a volume basis as measured by a laser diffraction type particle size distribution measuring apparatus (D 50 diameter).
本発明によれば、導電性が良好で安価な銀被覆ニッケル粉末を製造することができる。 According to the present invention, a silver-coated nickel powder having good conductivity and inexpensive can be produced.
本発明による銀被覆ニッケル粉末の製造方法の実施の形態では、ニッケル粉末を水素雰囲気中で還元することによってニッケル粉末中の酸素含有量を低減させた後、この酸素含有量を低減させたニッケル粉末の表面を銀含有層により被覆する。 In the embodiment of the method for producing a silver-coated nickel powder according to the present invention, the oxygen content in the nickel powder is reduced by reducing the nickel powder in a hydrogen atmosphere, and then the nickel powder in which the oxygen content is reduced is reduced. The surface of is covered with a silver-containing layer.
原料となるニッケル粉末は、ニッケルを溶解温度以上で溶解し、タンディッシュ下部から落下させながら高圧ガスまたは高圧水を衝突させて急冷凝固させることにより微粉末とする、（ガスアトマイズ法、水アトマイズ法などの）所謂アトマイズ法により製造するのが好ましい。特に、高圧水を吹き付ける、所謂水アトマイズ法により製造すると、粒子径が小さいニッケル粉末を得ることができるので、銀被覆ニッケル粉末を導電性ペーストに使用した際に粒子間の接触点の増加による導電性の向上を図ることができる。 Nickel powder, which is the raw material, melts nickel at a melting temperature or higher, and drops it from the bottom of the tundish while colliding it with high-pressure gas or high-pressure water to quench and solidify it into fine powder (gas atomization method, water atomization method, etc.). It is preferable to manufacture by the so-called atomizing method. In particular, when manufactured by the so-called water atomization method in which high-pressure water is sprayed, nickel powder having a small particle size can be obtained. Therefore, when silver-coated nickel powder is used as a conductive paste, conductivity is increased due to an increase in contact points between particles. It is possible to improve the sex.
このようにして得られたニッケル粉末の粒子径は、（ヘロス法によって）レーザー回折式粒度分布測定装置により測定した体積基準の累積５０％粒子径（Ｄ５０径）が０．１〜１５μｍであるのが好ましく、１〜１０μｍであるのがさらに好ましく、２〜５μｍであるのが最も好ましい。体積基準の累積５０％粒子径（Ｄ５０径）が０．１μｍ未満では、銀被覆ニッケル粉末の導電性に悪影響を及ぼすので好ましくない。一方、１５μｍを超えると、微細な配線の形成が困難になるので好ましくない。なお、ニッケル粉末をアトマイズ法により製造する場合、ニッケル溶湯に脱酸剤として少量のリン（Ｐ）を添加することにより、０．００１〜１質量％のＰを含むニッケル粉末を製造して、ニッケル粉末として使用してもよい。 The particle size of the nickel powder thus obtained has a volume-based cumulative 50% particle size (D50 size) measured by a laser diffraction particle size distribution measuring device (by the Heros method) of 0.1 to 15 μm. It is preferably 1 to 10 μm, more preferably 2 to 5 μm, and most preferably 2 to 5 μm. If the cumulative 50% particle diameter (D 50 diameter) based on the volume is less than 0.1 μm, it adversely affects the conductivity of the silver-coated nickel powder, which is not preferable. On the other hand, if it exceeds 15 μm, it becomes difficult to form fine wiring, which is not preferable. When nickel powder is produced by the atomizing method, nickel powder containing 0.001 to 1% by mass of P is produced by adding a small amount of phosphorus (P) as a deoxidizing agent to the molten nickel to produce nickel. It may be used as a powder.
ニッケル粉末中の酸素含有量の低減は、ニッケル粉末を水素雰囲気中で還元することによって行う。ニッケル粉末を水素雰囲気中で還元することによって、ニッケル粉末の（主に表面に存在する）酸素が除去される。また、ニッケル粉末を水素雰囲気中で還元することによって、ニッケル粉末の表面が銀含有層により被覆され易い状態になると考えられる。ニッケル粉末中の酸素含有量を低減させるために、ニッケル粉末を酸洗した場合、このように酸洗したニッケル粉末の表面を銀含有層で被覆しても、導電性が良好な銀被覆ニッケル粉末を得ることができない。 The oxygen content in the nickel powder is reduced by reducing the nickel powder in a hydrogen atmosphere. By reducing the nickel powder in a hydrogen atmosphere, the oxygen (mainly present on the surface) of the nickel powder is removed. Further, it is considered that by reducing the nickel powder in a hydrogen atmosphere, the surface of the nickel powder is easily covered with the silver-containing layer. When the nickel powder is pickled in order to reduce the oxygen content in the nickel powder, even if the surface of the nickel powder pickled in this way is coated with a silver-containing layer, the silver-coated nickel powder has good conductivity. Cannot be obtained.
水素雰囲気は、還元することができる程度の水素が存在する雰囲気であればよく、水素雰囲気中の水素濃度が５体積％以上であるのが好ましく、５０体積％以上であるのがさらに好ましい。ニッケル粉末の水素雰囲気中における還元は、ニッケル粉末を水素雰囲気中において加熱することによって行うのが好ましく、ニッケル粉末を十分に還元するために、加熱の温度が１００〜４００℃であるのが好ましく、加熱の時間が１〜２０時間であるのが好ましい。 The hydrogen atmosphere may be an atmosphere in which hydrogen that can be reduced is present, and the hydrogen concentration in the hydrogen atmosphere is preferably 5% by volume or more, and more preferably 50% by volume or more. The reduction of the nickel powder in a hydrogen atmosphere is preferably carried out by heating the nickel powder in a hydrogen atmosphere, and the heating temperature is preferably 100 to 400 ° C. in order to sufficiently reduce the nickel powder. The heating time is preferably 1 to 20 hours.
銀被覆ニッケル粉末の導電性を向上させるために、ニッケル粉末中の酸素含有量の低減により、酸素含有量が０．８質量％以下になるのが好ましく、０．５質量％以下になるのがさらに好ましい。また、銀被覆ニッケル粉末の導電性を向上させるために、ニッケル粉末のＢＥＴ比表面積に対する酸素含有量の比が２．０質量％・ｇ／ｍ２以下になるのが好ましく、１．０質量％・ｇ／ｍ２以下になるのがさらに好ましい。 In order to improve the conductivity of the silver-coated nickel powder, the oxygen content is preferably 0.8% by mass or less, preferably 0.5% by mass or less, by reducing the oxygen content in the nickel powder. More preferred. Further, in order to improve the conductivity of the silver-coated nickel powder, the ratio of the oxygen content to the BET specific surface area of the nickel powder is preferably 2.0% by mass · g / m 2 or less, preferably 1.0% by mass. -It is more preferable that it is g / m 2 or less.
銀含有層は、銀または銀化合物からなる層であるのが好ましい。銀被覆ニッケル粉末に対する銀含有層の被覆量は、３〜５０質量％であるのが好ましく、４〜４０質量％であるのがさらに好ましい。銀含有層の被覆量が３質量％未満では、銀被覆ニッケル粉末の導電性に悪影響を及ぼすので好ましくない。一方、５０質量％を超えると、銀の使用量の増加によってコストが高くなるので好ましくない。 The silver-containing layer is preferably a layer made of silver or a silver compound. The coating amount of the silver-containing layer with respect to the silver-coated nickel powder is preferably 3 to 50% by mass, more preferably 4 to 40% by mass. If the coating amount of the silver-containing layer is less than 3% by mass, the conductivity of the silver-coated nickel powder is adversely affected, which is not preferable. On the other hand, if it exceeds 50% by mass, the cost increases due to the increase in the amount of silver used, which is not preferable.
ニッケル粉末を銀含有層で被覆する方法として、ニッケルと銀の置換反応を利用した置換法や、還元剤を用いる還元法により、ニッケル粉末の表面に銀または銀化合物を析出させる方法を使用することができ、例えば、溶媒中にニッケル粉末と銀または銀化合物を含む溶液を攪拌しながらニッケル粉末の表面に銀または銀化合物を析出させる方法や、溶媒中にニッケル粉末および有機物を含む溶液と溶媒中に銀または銀化合物および有機物を含む溶液とを混合して攪拌しながらニッケル粉末の表面に銀または銀化合物を析出させる方法などを使用することができる。 As a method of coating the nickel powder with a silver-containing layer, a method of precipitating silver or a silver compound on the surface of the nickel powder by a substitution method using a substitution reaction between nickel and silver or a reduction method using a reducing agent is used. For example, a method of precipitating silver or a silver compound on the surface of a nickel powder while stirring a solution containing the nickel powder and a silver or a silver compound in a solvent, or a solution containing a nickel powder and an organic substance in the solvent and a solvent. A method of precipitating the silver or the silver compound on the surface of the nickel powder while mixing the mixture with the silver or the silver compound and the solution containing the organic substance and stirring the mixture can be used.
この溶媒としては、水、有機溶媒またはこれらを混合した溶媒を使用することができる。水と有機溶媒を混合した溶媒を使用する場合には、室温（２０〜３０℃）において液体になる有機溶媒を使用する必要があるが、水と有機溶媒の混合比率は、使用する有機溶媒により適宜調整することができる。また、溶媒として使用する水は、不純物が混入するおそれがなければ、蒸留水、イオン交換水、工業用水などを使用することができる。 As the solvent, water, an organic solvent, or a solvent obtained by mixing these can be used. When using a solvent in which water and an organic solvent are mixed, it is necessary to use an organic solvent that becomes liquid at room temperature (20 to 30 ° C.), but the mixing ratio of water and the organic solvent depends on the organic solvent used. It can be adjusted as appropriate. Further, as the water used as the solvent, distilled water, ion-exchanged water, industrial water and the like can be used as long as there is no risk of impurities being mixed.
銀含有層をより均一に形成するために、溶液中にキレート化剤を添加してもよい。キレート化剤としては、銀イオンと金属ニッケルとの置換反応により副生するニッケルイオンなどが再析出しないように、ニッケルイオンなどに対して錯安定度定数が高いキレート化剤を使用するのが好ましい。特に、銀被覆ニッケル粉末のコアとなるニッケル粉末は主構成要素としてニッケルを含んでいるので、ニッケルとの錯安定度定数に留意してキレート化剤を選択するのが好ましい。具体的には、キレート化剤として、エチレンジアミン四酢酸（ＥＤＴＡ）、イミノジ酢酸、ジエチレントリアミン、トリエチレンジアミンおよびこれらの塩からなる群から選ばれたキレート化剤を使用することができる。 A chelating agent may be added to the solution to form the silver-containing layer more uniformly. As the chelating agent, it is preferable to use a chelating agent having a high complex stability constant with respect to nickel ions and the like so that nickel ions and the like produced as a by-product due to the substitution reaction between silver ions and metallic nickel do not reprecipitate. .. In particular, since nickel powder, which is the core of silver-coated nickel powder, contains nickel as a main component, it is preferable to select a chelating agent while paying attention to the illusion stability constant with nickel. Specifically, as the chelating agent, a chelating agent selected from the group consisting of ethylenediaminetetraacetic acid (EDTA), iminodiacetic acid, diethylenetriamine, triethylenediamine and salts thereof can be used.
銀被覆反応の際には、銀塩を添加する前に溶液中にニッケル粉末を入れて攪拌し、ニッケル粉末が溶液中に十分に分散している状態で、銀塩を含む溶液を添加するのが好ましい。この銀塩を含む溶液は、一挙に（好ましくは４０秒以下の短時間で）添加してもよいし、反応速度を制御するために、連続的に（好ましくは１０分間以上の時間で）添加してもよい。この銀被覆反応の際の反応温度は、反応液が凝固または蒸発する温度でなければよいが、好ましくは４０〜９５℃、さらに好ましくは６０〜９０℃の範囲で設定する。また、反応時間は、銀または銀化合物の被覆量や反応温度によって異なるが、１分〜５時間の範囲で設定することができる。 In the silver coating reaction, nickel powder is put in the solution and stirred before adding the silver salt, and the solution containing the silver salt is added with the nickel powder sufficiently dispersed in the solution. Is preferable. The solution containing the silver salt may be added all at once (preferably in a short time of 40 seconds or less), or continuously (preferably in a time of 10 minutes or more) to control the reaction rate. You may. The reaction temperature at the time of this silver coating reaction may not be the temperature at which the reaction solution solidifies or evaporates, but is preferably set in the range of 40 to 95 ° C, more preferably 60 to 90 ° C. The reaction time varies depending on the coating amount of silver or the silver compound and the reaction temperature, but can be set in the range of 1 minute to 5 hours.
上述した銀被覆ニッケル粉末の製造方法の実施の形態により、本発明による銀被覆ニッケル粉末の実施の形態を製造することができる。 According to the embodiment of the method for producing silver-coated nickel powder described above, the embodiment of silver-coated nickel powder according to the present invention can be produced.
本発明による銀被覆ニッケル粉末の実施の形態では、表面が３〜５０質量％（好ましくは４〜４０質量％）の銀含有層により被覆され、酸素含有量が０．７質量％以下（好ましくは０．６質量％以下）であり、色差（Ｌ＊）が４８以上（好ましくは５０〜８０）である。 In the embodiment of the silver-coated nickel powder according to the present invention, the surface is coated with a silver-containing layer of 3 to 50% by mass (preferably 4 to 40% by mass), and the oxygen content is 0.7% by mass or less (preferably). It is 0.6% by mass or less), and the color difference (L * ) is 48 or more (preferably 50 to 80).
この銀被覆ニッケル粉末の導電性を向上させるために、銀被覆ニッケル粉末のＢＥＴ比表面積に対する酸素含有量の比が、１．０質量％・ｇ／ｍ２以下であるのが好ましく、０．８質量％・ｇ／ｍ２以下であるのがさらに好ましい。また、銀被覆ニッケル粉末に５．６ＭＰａの圧力を加えたときの体積抵抗率が、０．１〜１０ｍΩ・ｃｍであるのが好ましく、０．１〜５ｍΩ・ｃｍであるのがさらに好ましく０．１〜２ｍΩ・ｃｍであるのが最も好ましい。また、銀被覆ニッケル粉末に１０ＭＰａの圧力を加えたときの体積抵抗率が、０．０５〜６ｍΩ・ｃｍであるのが好ましく、０．０８〜３ｍΩ・ｃｍであるのがさらに好ましく０．１〜１．２ｍΩ・ｃｍであるのが最も好ましい。 In order to improve the conductivity of the silver-coated nickel powder, the ratio of the oxygen content to the BET specific surface area of the silver-coated nickel powder is preferably 1.0% by mass · g / m 2 or less, preferably 0.8. It is more preferably mass% · g / m 2 or less. Further, the volume resistivity when a pressure of 5.6 MPa is applied to the silver-coated nickel powder is preferably 0.1 to 10 mΩ · cm, and more preferably 0.1 to 5 mΩ · cm. Most preferably, it is 1 to 2 mΩ · cm. The volume resistivity of the silver-coated nickel powder when a pressure of 10 MPa is applied is preferably 0.05 to 6 mΩ · cm, more preferably 0.08 to 3 mΩ · cm. Most preferably, it is 1.2 mΩ · cm.
上述した銀被覆ニッケル粉末の製造方法の実施の形態では、ニッケル粉末を水素雰囲気中で還元することによって予めニッケル粉末中の酸素含有量を低減させており、このように酸素含有量を低減させることによって、ニッケル粉末の表面を銀含有層により均一に被覆することができ、このようにニッケル粉末の表面を銀含有層により均一に被覆することによって、銀被覆ニッケル粉末の色差（Ｌ＊）の値が高くなり、銀被覆ニッケル粉末に圧力を加えたときの体積抵抗率も低くなる。なお、上述した銀被覆ニッケル粉末の製造方法の実施の形態では、銀被覆ニッケル粉末の色差（Ｌ＊）の値を８０まで高くすることができ、銀被覆ニッケル粉末の導電性を向上させるために、銀被覆ニッケル粉末の色差（Ｌ＊）の値が５０〜８０であるのが好ましい。 In the embodiment of the method for producing silver-coated nickel powder described above, the oxygen content in the nickel powder is reduced in advance by reducing the nickel powder in a hydrogen atmosphere, and thus the oxygen content is reduced. Therefore, the surface of the nickel powder can be uniformly coated with the silver-containing layer, and by uniformly coating the surface of the nickel powder with the silver-containing layer in this way, the value of the color difference (L *) of the silver-coated nickel powder. And the volume resistivity when pressure is applied to the silver-coated nickel powder is also low. In the embodiment of the method for producing silver-coated nickel powder described above, the value of the color difference (L *) of the silver-coated nickel powder can be increased to 80, in order to improve the conductivity of the silver-coated nickel powder. , The value of the color difference (L *) of the silver-coated nickel powder is preferably 50 to 80.
また、銀被覆ニッケル粉末の粒子径は、（ヘロス法によって）レーザー回折式粒度分布測定装置により測定した体積基準の累積５０％粒子径（Ｄ５０径）が０．１〜１５μｍであるのが好ましく、１〜１０μｍであるのがさらに好ましく、２〜７μｍであるのが最も好ましい。体積基準の累積５０％粒子径（Ｄ５０径）が０．１μｍ未満では、銀被覆ニッケル粉末の導電性に悪影響を及ぼすので好ましくない。一方、１５μｍを超えると、微細な配線の形成が困難になるので好ましくない。 The particle diameter of the silver-coated nickel powder is preferably from 50% cumulative particle diameter on a volume basis as measured by (Heroes method by) a laser diffraction type particle size distribution measuring apparatus (D 50 diameter) 0.1~15μm It is more preferably 1 to 10 μm, and most preferably 2 to 7 μm. If the cumulative 50% particle diameter (D 50 diameter) based on the volume is less than 0.1 μm, it adversely affects the conductivity of the silver-coated nickel powder, which is not preferable. On the other hand, if it exceeds 15 μm, it becomes difficult to form fine wiring, which is not preferable.
また、銀被覆ニッケル粉末のＢＥＴ比表面積は、０．１〜５ｍ２／ｇであるのが好ましく、０．１〜２ｍ２／ｇであるのがさらに好ましく、０．１〜１ｍ２／ｇであるのが最も好ましい。ＢＥＴ比表面積が０．１ｍ２／ｇ未満では、微細な配線の形成が困難になるので好ましくない。一方、５ｍ２／ｇを超えると、銀被覆ニッケル粉末を導電性ペーストに使用した際に粘度が高くなり過ぎるので好ましくない。 Further, BET specific surface area of the silver-coated nickel powder is preferably from 0.1 to 5 m 2 / g, more preferably from 0.1~2m 2 / g, with 0.1 to 1 m 2 / g Most preferably. If the BET specific surface area is less than 0.1 m 2 / g, it becomes difficult to form fine wiring, which is not preferable. On the other hand, if it exceeds 5 m 2 / g, the viscosity becomes too high when the silver-coated nickel powder is used for the conductive paste, which is not preferable.
なお、銀被覆ニッケル粉末中の塩素含有量は、１００ｐｐｍ未満であるのが好ましく、５０ｐｐｍ未満であるのがさらに好ましく、１０ｐｐｍ未満であるのが最も好ましい。塩素含有量が１００ｐｐｍ以上になると、銀被覆ニッケル粉末を導電性ペーストに使用して配線を形成した際に、配線が腐食して導電性が悪化し易くなる。このように塩素含有量が少ない銀被覆ニッケル粉末は、アトマイズ法で製造したニッケル粉末を銀含有層により被覆することによって得ることができる。 The chlorine content in the silver-coated nickel powder is preferably less than 100 ppm, more preferably less than 50 ppm, and most preferably less than 10 ppm. When the chlorine content is 100 ppm or more, when the silver-coated nickel powder is used for the conductive paste to form the wiring, the wiring is easily corroded and the conductivity is easily deteriorated. The silver-coated nickel powder having such a low chlorine content can be obtained by coating the nickel powder produced by the atomizing method with a silver-containing layer.
以下、本発明による銀被覆ニッケル粉末およびその製造方法の実施例について詳細に説明する。 Hereinafter, examples of the silver-coated nickel powder according to the present invention and the method for producing the same will be described in detail.
［実施例１］
純度９９．９９％のニッケル１５ｋｇを１６００℃に加熱して溶解した溶湯をタンディッシュ下部から落下させながら、大気雰囲気中において水圧１５０ＭＰａで高圧水を吹き付けて急冷凝固させ、得られたスラリーを固液分離し、固形分を水洗し、乾燥し、解砕し、分級して、ニッケル粉末を得た。
[Example 1]
While 15 kg of nickel with a purity of 99.99% was heated to 1600 ° C. and the molten metal dissolved was dropped from the lower part of the tundish, high-pressure water was sprayed at a water pressure of 150 MPa to quench and solidify the obtained slurry. The solids were separated, washed with water, dried, crushed and classified to give a nickel powder.
このようにして水アトマイズ法により得られたニッケル粉末を、水素雰囲気（水素１００体積％）中において２００℃で１０時間加熱して熱処理を行い、水素還元したニッケル粉末を得た。 The nickel powder thus obtained by the water atomization method was heated at 200 ° C. for 10 hours in a hydrogen atmosphere (100% by volume of hydrogen) and heat-treated to obtain a hydrogen-reduced nickel powder.
このように水素還元したニッケル粉末（銀被覆前のニッケル粉末）について、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量および粒度分布を求めた。 For the nickel powder thus hydrogen-reduced (nickel powder before silver coating), the BET specific surface area, tap density, oxygen content, carbon content and particle size distribution were determined.
ＢＥＴ比表面積は、測定器内に１０５℃で２０分間窒素ガスを流して脱気した後、ＢＥＴ比表面積測定器（ユアサアイオニクス株式会社製の４ソーブＵＳ）を使用し、測定器内に１０５℃で２０分間窒素ガスを流して脱気した後、３０体積％の窒素と７０体積％のヘリウムの混合ガスを流しながら、ＢＥＴ１点法により測定した。その結果、ＢＥＴ比表面積は０．４５ｍ２／ｇであった。 The BET specific surface area was degassed by flowing nitrogen gas into the measuring instrument at 105 ° C. for 20 minutes, and then using a BET specific surface area measuring instrument (4 Sorb US manufactured by Yuasa Ionics Co., Ltd.), the BET specific surface area was 105 in the measuring instrument. After degassing by flowing nitrogen gas at ° C. for 20 minutes, the measurement was carried out by the BET 1-point method while flowing a mixed gas of 30% by volume nitrogen and 70% by volume helium. As a result, the BET specific surface area was 0.45 m 2 / g.
タップ密度（ＴＡＰ）は、ニッケル粉末０．５ｇを内径６ｍｍの有底円筒形のダイに充填してニッケル粉末層を形成し、このニッケル粉末層の上面に０．１６Ｎ／ｍ２の圧力を均一に加えた後、ニッケル粉末粉層の高さを測定し、このニッケル粉末層の高さの測定値と、充填されたニッケル粉末の重量とから、ニッケル粉末の密度を求めて、ニッケル粉末のタップ密度とした。その結果、タップ密度は４．３ｇ／ｃｍ３であった。 The tap density (TAP) is such that 0.5 g of nickel powder is filled in a bottomed cylindrical die having an inner diameter of 6 mm to form a nickel powder layer, and a pressure of 0.16 N / m 2 is uniformly applied to the upper surface of the nickel powder layer. After adding to, measure the height of the nickel powder layer, determine the density of the nickel powder from the measured value of the height of this nickel powder layer and the weight of the filled nickel powder, and tap the nickel powder. The density was set. As a result, the tap density was 4.3 g / cm 3 .
酸素含有量は、酸素・窒素・水素分析装置（株式会社堀場製作所製のＥＭＧＡ−９２０）により測定した。その結果、酸素含有量は０．３７質量％であった。なお、ＢＥＴ比表面積に対する酸素含有量は０．８２質量％・ｇ／ｍ２になる。 The oxygen content was measured with an oxygen / nitrogen / hydrogen analyzer (EMGA-920 manufactured by HORIBA, Ltd.). As a result, the oxygen content was 0.37% by mass. The oxygen content with respect to the BET specific surface area is 0.82% by mass · g / m 2 .
炭素含有量は、炭素・硫黄分析装置（株式会社堀場製作所製のＥＭＩＡ−２２０Ｖ）により測定した。その結果、炭素含有量は０．０１質量％であった。 The carbon content was measured with a carbon / sulfur analyzer (EMIA-220V manufactured by HORIBA, Ltd.). As a result, the carbon content was 0.01% by mass.
粒度分布は、レーザー回折式粒度分布測定装置（ＳＹＭＰＡＴＥＣ社製のへロス粒度分布測定装置（ＨＥＬＯＳ＆ＲＯＤＯＳ（気流式の分散モジュール））を使用して、分散圧５ｂａｒで測定した。その結果、累積１０％粒子径（Ｄ１０）は１．１μｍ、累積５０％粒子径（Ｄ５０）は２．９μｍ、累積９０％粒子径（Ｄ９０）は７．０μｍであった。 The particle size distribution was measured at a dispersion pressure of 5 bar using a laser diffraction type particle size distribution measuring device (a Heros particle size distribution measuring device (HELOS & RODOS (air flow type dispersion module)) manufactured by SYMPATEC). As a result, the cumulative total was 10%. The particle size (D 10 ) was 1.1 μm, the cumulative 50% particle size (D 50 ) was 2.9 μm, and the cumulative 90% particle size (D 90 ) was 7.0 μm.
また、ＥＤＴＡ−２Ｎａ二水和物 １１９．０ｇと炭酸アンモニウム１１９．０ｇを純水１３８５．０ｇに溶解して７０℃まで昇温した溶液（溶液１）と、ＥＤＴＡ−２Ｎａ二水和物５５４．１ｇと炭酸アンモニウム２７７．１ｇを純水２２０７．２ｇに溶解して７０℃まで昇温した溶液に、３０％硝酸銀水溶液１９２．４ｇを純水１８５．３ｇに溶解した溶液を加えて得られた溶液（溶液２）を用意した。 Further, a solution (solution 1) in which 119.0 g of EDTA-2Na dihydrate and 119.0 g of ammonium carbonate were dissolved in 1385.0 g of pure water and heated to 70 ° C., and EDTA-2Na dihydrate 554. A solution obtained by dissolving 1 g and 277.1 g of ammonium carbonate in 2207.2 g of pure water and raising the temperature to 70 ° C., and adding a solution of 192.4 g of a 30% silver nitrate aqueous solution in 185.3 g of pure water. (Solution 2) was prepared.
次に、窒素雰囲気下において、上記の水素還元したニッケル粉末２５０ｇを溶液１に加えて攪拌し、この水素還元したニッケル粉末が分散した溶液に溶液２を３０分間かけて添加して攪拌した後、固液分離し、水洗し、真空中において７０℃で１０時間乾燥し、解砕し、篩分して、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。 Next, in a nitrogen atmosphere, 250 g of the above hydrogen-reduced nickel powder was added to solution 1 and stirred, and solution 2 was added to the solution in which the hydrogen-reduced nickel powder was dispersed over 30 minutes and stirred. The mixture was solid-liquid separated, washed with water, dried in vacuum at 70 ° C. for 10 hours, crushed and sieved to obtain a silver-coated nickel powder (silver-coated nickel powder).
このようにして得られた銀被覆ニッケル粉末について、上記と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量および粒度分布を求めるとともに、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content and particle size distribution are determined by the same method as described above, and the silver coating amount and color difference (L * ,) are obtained. a * , b * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．６２ｍ２／ｇ、タップ密度は４．４ｇ／ｃｍ３、酸素含有量は０．３６質量％、ＢＥＴ比表面積に対する酸素含有量は０．５８質量％・ｇ／ｍ２、炭素含有量は０．０２質量％であり、累積１０％粒子径（Ｄ１０）は１．２μｍ、累積５０％粒子径（Ｄ５０）は３．３μｍ、累積９０％粒子径（Ｄ９０）は８．１μｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.62 m 2 / g, the tap density was 4.4 g / cm 3 , the oxygen content was 0.36% by mass, and the oxygen content with respect to the BET specific surface area was 0.58. Mass% · g / m 2 , carbon content is 0.02 mass%, cumulative 10% particle size (D 10 ) is 1.2 μm, cumulative 50% particle size (D 50 ) is 3.3 μm, cumulative 90 The% particle size (D 90 ) was 8.1 μm.
銀被覆ニッケル粉末の銀被覆量は、銀被覆ニッケル粉末を硝酸で溶解した後、塩酸を添加して生成した塩化銀（ＡｇＣｌ）の沈殿を乾燥し、重量を測定することにより求めた。その結果、銀被覆ニッケル粉末中の銀含有量（銀被覆量）は２０．８質量％であった。 The silver coating amount of the silver-coated nickel powder was determined by dissolving the silver-coated nickel powder with nitric acid, drying the precipitate of silver chloride (AgCl) produced by adding hydrochloric acid, and measuring the weight. As a result, the silver content (silver coating amount) in the silver-coated nickel powder was 20.8% by mass.
銀被覆ニッケル粉末の色差は、測定試料として銀被覆ニッケル粉末５ｇを秤量して直径３０ｍｍの丸セルに入れ、１０回タッピングして表面を平らにし、色差計（日本電色工業株式会社製のＳｐｅｃｔｒｏ Ｃｏｌｏｒ Ｍｅｔｅｒ ＳＱ２０００）を使用して、ＳＣＥ（正反射光除去）モードで測定した。その結果、銀被覆ニッケル粉末の色差Ｌ＊、ａ＊およびｂ＊はそれぞれ５８．１、０．０および６．１であった。 For the color difference of silver-coated nickel powder, weigh 5 g of silver-coated nickel powder as a measurement sample, put it in a round cell with a diameter of 30 mm, tap it 10 times to flatten the surface, and use a color difference meter (Specuro manufactured by Nippon Denshoku Industries Co., Ltd.). Color Meter SQ2000) was used to measure in SCE (Specular Elimination) mode. As a result, the color differences L * , a * and b * of the silver-coated nickel powder were 58.1, 0.0 and 6.1, respectively.
銀被覆ニッケル粉末の圧粉体抵抗として、銀被覆ニッケル粉末６．０ｇを粉体抵抗測定システムの測定容器（三菱化学アナリテック株式会社製のＭＣＰ−ＰＤ５１型）内に詰めた後に加圧を開始して、それぞれ５．６ＭＰａおよび１０ＭＰａの荷重がかかった時点の（圧粉体の）体積抵抗率を測定した。その結果、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ０．２７ｍΩ・ｃｍおよび０．１９ｍΩ・ｃｍであった。 As the green compact resistance of silver-coated nickel powder, pressurization is started after 6.0 g of silver-coated nickel powder is packed in the measuring container of the powder resistivity measurement system (MCP-PD51 type manufactured by Mitsubishi Chemical Analytech Co., Ltd.). Then, the volume resistivity (of the green compact) at the time when the loads of 5.6 MPa and 10 MPa were applied, respectively, was measured. As a result, the volume resistivity of the green compact of the silver-coated nickel powder was 0.27 mΩ · cm and 0.19 mΩ · cm, respectively.
［実施例２］
ＥＤＴＡ−２Ｎａ二水和物 ２３８．０ｇと炭酸アンモニウム２３８．０ｇを純水２７７０．０ｇに溶解して７０℃まで昇温した溶液（溶液１）と、ＥＤＴＡ−２Ｎａ二水和物２４８．７ｇと炭酸アンモニウム１２４．３ｇを純水９９０．５ｇに溶解して７０℃まで昇温した溶液に、３０％硝酸銀水溶液８６．３ｇを純水８６．２ｇに溶解した溶液を加えて得られた溶液（溶液２）を使用し、実施例１と同様の水素還元したニッケル粉末５００ｇを使用した以外は、実施例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Example 2]
A solution (solution 1) in which 238.0 g of EDTA-2Na dihydrate and 238.0 g of ammonium carbonate were dissolved in 2770.0 g of pure water and heated to 70 ° C., and 248.7 g of EDTA-2Na dihydrate. A solution (solution) obtained by adding a solution of 86.3 g of a 30% silver nitrate aqueous solution in 86.2 g of pure water to a solution of 124.3 g of ammonium carbonate dissolved in 990.5 g of pure water and heated to 70 ° C. 2) was used, and a silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Example 1 except that 500 g of the same hydrogen-reduced nickel powder as in Example 1 was used.
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．７４ｍ２／ｇ、タップ密度は４．６ｇ／ｃｍ３、酸素含有量は０．５５質量％、ＢＥＴ比表面積に対する酸素含有量は０．７４質量％・ｇ／ｍ２、炭素含有量は０．０３質量％であり、累積１０％粒子径（Ｄ１０）は１．１μｍ、累積５０％粒子径（Ｄ５０）は３．０μｍ、累積９０％粒子径（Ｄ９０）は１４．１μｍであった。また、銀含有量（銀被覆量）は５．２質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ５２．１、０．２および５．９であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ１．６ｍΩ・ｃｍおよび０．９ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.74 m 2 / g, the tap density was 4.6 g / cm 3 , the oxygen content was 0.55% by mass, and the oxygen content with respect to the BET specific surface area was 0.74. Mass% · g / m 2 , carbon content is 0.03 mass%, cumulative 10% particle size (D 10 ) is 1.1 μm, cumulative 50% particle size (D 50 ) is 3.0 μm, cumulative 90 The% particle size (D 90 ) was 14.1 μm. The silver content (silver coating amount) was 5.2% by mass, and the color differences L * , a * and b * were 52.1, 0.2 and 5.9, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 1.6 mΩ · cm and 0.9 mΩ · cm, respectively.
［実施例３］
ＥＤＴＡ−２Ｎａ二水和物１６６．６ｇと炭酸アンモニウム１６６．６ｇを純水１９３９．０ｇに溶解して７０℃まで昇温した溶液（溶液１）と、ＥＤＴＡ−２Ｎａ二水和物３６７．５ｇと炭酸アンモニウム１８３．７ｇを純水１４６３．７ｇに溶解して７０℃まで昇温した溶液に、３０％硝酸銀水溶液１２７．６ｇを純水１２２．９ｇに溶解した溶液を加えて得られた溶液（溶液２）を使用し、実施例１と同様の水素還元したニッケル粉末３５０ｇを使用した以外は、実施例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Example 3]
A solution (solution 1) in which 166.6 g of EDTA-2Na dihydrate and 166.6 g of ammonium carbonate were dissolved in 1939.0 g of pure water and heated to 70 ° C., and 367.5 g of EDTA-2Na dihydrate. A solution (solution) obtained by dissolving 183.7 g of ammonium carbonate in 1463.7 g of pure water and raising the temperature to 70 ° C., and adding a solution of 127.6 g of a 30% silver nitrate aqueous solution in 122.9 g of pure water. 2) was used, and a silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Example 1 except that 350 g of the same hydrogen-reduced nickel powder as in Example 1 was used.
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．８４ｍ２／ｇ、タップ密度は４．５ｇ／ｃｍ３、酸素含有量は０．５４質量％、ＢＥＴ比表面積に対する酸素含有量は０．６４質量％・ｇ／ｍ２、炭素含有量は０．０３質量％であり、累積１０％粒子径（Ｄ１０）は１．２μｍ、累積５０％粒子径（Ｄ５０）は３．１μｍ、累積９０％粒子径（Ｄ９０）は８．０μｍであった。また、銀含有量（銀被覆量）は１０．１質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ５１．８、０．２および５．６であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ１．１ｍΩ・ｃｍおよび０．６６ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.84 m 2 / g, the tap density was 4.5 g / cm 3 , the oxygen content was 0.54% by mass, and the oxygen content with respect to the BET specific surface area was 0.64. Mass% · g / m 2 , carbon content is 0.03 mass%, cumulative 10% particle size (D 10 ) is 1.2 μm, cumulative 50% particle size (D 50 ) is 3.1 μm, cumulative 90 The% particle size (D 90 ) was 8.0 μm. The silver content (silver coating amount) was 10.1% by mass, and the color differences L * , a * and b * were 51.8, 0.2 and 5.6, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 1.1 mΩ · cm and 0.66 mΩ · cm, respectively.
［実施例４］
ＥＤＴＡ−２Ｎａ二水和物１４２．８ｇと炭酸アンモニウム１４２．８ｇを純水１６６２．０ｇに溶解して７０℃まで昇温した溶液（溶液１）と、ＥＤＴＡ−２Ｎａ二水和物４８０．７ｇと炭酸アンモニウム２４０．４ｇを純水１９１４．９ｇに溶解して７０℃まで昇温した溶液に、３０％硝酸銀水溶液１６６．９ｇを純水１６０．８ｇに溶解した溶液を加えて得られた溶液（溶液２）を使用し、実施例１と同様の水素還元したニッケル粉末３００ｇを使用した以外は、実施例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Example 4]
A solution (solution 1) in which 142.8 g of EDTA-2Na dihydrate and 142.8 g of ammonium carbonate were dissolved in 1662.0 g of pure water and heated to 70 ° C., and 480.7 g of EDTA-2Na dihydrate A solution (solution) obtained by adding a solution of 166.9 g of a 30% silver nitrate aqueous solution in 160.8 g of pure water to a solution in which 240.4 g of ammonium carbonate was dissolved in 1914.9 g of pure water and the temperature was raised to 70 ° C. 2) was used, and a silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Example 1 except that 300 g of the same hydrogen-reduced nickel powder as in Example 1 was used.
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．８０ｍ２／ｇ、タップ密度は４．４ｇ／ｃｍ３、酸素含有量は０．５２質量％、ＢＥＴ比表面積に対する酸素含有量は０．６５質量％・ｇ／ｍ２、炭素含有量は０．０３質量％であり、累積１０％粒子径（Ｄ１０）は１．２μｍ、累積５０％粒子径（Ｄ５０）は３．１μｍ、累積９０％粒子径（Ｄ９０）は７．７μｍであった。また、銀含有量（銀被覆量）は１５．５質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ５５．３、０．２および５．７であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ１．２ｍΩ・ｃｍおよび０．７ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.80 m 2 / g, the tap density was 4.4 g / cm 3 , the oxygen content was 0.52% by mass, and the oxygen content with respect to the BET specific surface area was 0.65. Mass% · g / m 2 , carbon content is 0.03 mass%, cumulative 10% particle size (D 10 ) is 1.2 μm, cumulative 50% particle size (D 50 ) is 3.1 μm, cumulative 90 The% particle size (D 90 ) was 7.7 μm. The silver content (silver coating amount) was 15.5% by mass, and the color differences L * , a * and b * were 55.3, 0.2 and 5.7, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 1.2 mΩ · cm and 0.7 mΩ · cm, respectively.
［実施例５］
ＥＤＴＡ−２Ｎａ二水和物８８．１ｇと炭酸アンモニウム８８．１ｇを純水１０２４．９ｇに溶解して７０℃まで昇温した溶液（溶液１）と、ＥＤＴＡ−２Ｎａ二水和物７３１．５ｇと炭酸アンモニウム３６５．７ｇを純水２９１３．６ｇに溶解して７０℃まで昇温した溶液に、３０％硝酸銀水溶液２５４．０ｇを純水２４４．６ｇに溶解した溶液を加えて得られた溶液（溶液２）を使用し、実施例１と同様の水素還元したニッケル粉末１８５ｇを使用した以外は、実施例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Example 5]
A solution (solution 1) in which 88.1 g of EDTA-2Na dihydrate and 88.1 g of ammonium carbonate were dissolved in 1024.9 g of pure water and heated to 70 ° C., and 731.5 g of EDTA-2Na dihydrate A solution (solution) obtained by adding a solution of 254.0 g of a 30% silver nitrate aqueous solution in 244.6 g of pure water to a solution in which 365.7 g of ammonium carbonate was dissolved in 2913.6 g of pure water and the temperature was raised to 70 ° C. 2) was used, and a silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Example 1 except that 185 g of the same hydrogen-reduced nickel powder as in Example 1 was used.
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．７０ｍ２／ｇ、タップ密度は４．１ｇ／ｃｍ３、酸素含有量は０．３４質量％、ＢＥＴ比表面積に対する酸素含有量は０．４９質量％・ｇ／ｍ２、炭素含有量は０．０２質量％であり、累積１０％粒子径（Ｄ１０）は１．４μｍ、累積５０％粒子径（Ｄ５０）は３．８μｍ、累積９０％粒子径（Ｄ９０）は１０．２μｍであった。また、銀含有量（銀被覆量）は３４．０質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ５９．４、−０．１および６．４であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ１．８ｍΩ・ｃｍおよび０．１３ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.70 m 2 / g, the tap density was 4.1 g / cm 3 , the oxygen content was 0.34% by mass, and the oxygen content with respect to the BET specific surface area was 0.49. Mass% · g / m 2 , carbon content is 0.02 mass%, cumulative 10% particle size (D 10 ) is 1.4 μm, cumulative 50% particle size (D 50 ) is 3.8 μm, cumulative 90 The% particle size (D 90 ) was 10.2 μm. The silver content (silver coating amount) was 34.0% by mass, and the color differences L * , a * and b * were 59.4, −0.1 and 6.4, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 1.8 mΩ · cm and 0.13 mΩ · cm, respectively.
［実施例６］
溶液２を３０分間かけて添加する代わりに５秒間で一挙に添加した以外は、実施例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Example 6]
A silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Example 1 except that the solution 2 was added all at once in 5 seconds instead of being added over 30 minutes.
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．５３ｍ２／ｇ、タップ密度は４．７ｇ／ｃｍ３、酸素含有量は０．３８質量％、ＢＥＴ比表面積に対する酸素含有量は０．７２質量％・ｇ／ｍ２、炭素含有量は０．０２質量％であり、累積１０％粒子径（Ｄ１０）は１．２μｍ、累積５０％粒子径（Ｄ５０）は３．４μｍ、累積９０％粒子径（Ｄ９０）は７．８μｍであった。また、銀含有量（銀被覆量）は２１．３質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ５６．６、−０．１および５．２であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ１．０ｍΩ・ｃｍおよび０．６１ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.53 m 2 / g, the tap density was 4.7 g / cm 3 , the oxygen content was 0.38% by mass, and the oxygen content with respect to the BET specific surface area was 0.72. Mass% · g / m 2 , carbon content is 0.02 mass%, cumulative 10% particle size (D 10 ) is 1.2 μm, cumulative 50% particle size (D 50 ) is 3.4 μm, cumulative 90 The% particle size (D 90 ) was 7.8 μm. The silver content (silver coating amount) was 21.3% by mass, and the color differences L * , a * and b * were 56.6, −0.1 and 5.2, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 1.0 mΩ · cm and 0.61 mΩ · cm, respectively.
［比較例１］
水素還元を行わなかった以外は、実施例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。なお、銀被覆前のニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量および粒度分布を求めたところ、ＢＥＴ比表面積は０．４４ｍ２／ｇ、タップ密度は５．０ｇ／ｃｍ３、酸素含有量は０．９６質量％、ＢＥＴ比表面積に対する酸素含有量は２．１８質量％・ｇ／ｍ２、炭素含有量は０．０１質量％であり、累積１０％粒子径（Ｄ１０）は１．１μｍ、累積５０％粒子径（Ｄ５０）は２．７μｍ、累積９０％粒子径（Ｄ９０）は６．５μｍであった。
[Comparative Example 1]
A silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Example 1 except that hydrogen reduction was not performed. The BET specific surface area, tap density, oxygen content, carbon content, and particle size distribution of the nickel powder before silver coating were determined by the same method as in Example 1. As a result, the BET specific surface area was 0.44 m 2 /. g, tap density is 5.0 g / cm 3 , oxygen content is 0.96 mass%, oxygen content with respect to BET specific surface area is 2.18 mass% · g / m 2 , carbon content is 0.01 mass%. The cumulative 10% particle size (D 10 ) was 1.1 μm, the cumulative 50% particle size (D 50 ) was 2.7 μm, and the cumulative 90% particle size (D 90 ) was 6.5 μm.
得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the obtained silver-coated nickel powder, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a * , b *) were carried out in the same manner as in Example 1. ) And powder compaction resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．６６ｍ２／ｇ、タップ密度は４．７ｇ／ｃｍ３、酸素含有量は０．７７質量％、ＢＥＴ比表面積に対する酸素含有量は１．１７質量％・ｇ／ｍ２、炭素含有量は０．０２質量％であり、累積１０％粒子径（Ｄ１０）は１．２μｍ、累積５０％粒子径（Ｄ５０）は３．０μｍ、累積９０％粒子径（Ｄ９０）は７．６μｍであった。また、銀含有量（銀被覆量）は１９．６質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ４５．６、０．２および８．４であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ３６ｍΩ・ｃｍおよび１８ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.66 m 2 / g, the tap density was 4.7 g / cm 3 , the oxygen content was 0.77% by mass, and the oxygen content with respect to the BET specific surface area was 1.17. Mass% · g / m 2 , carbon content is 0.02 mass%, cumulative 10% particle size (D 10 ) is 1.2 μm, cumulative 50% particle size (D 50 ) is 3.0 μm, cumulative 90 The% particle size (D 90 ) was 7.6 μm. The silver content (silver coating amount) was 19.6% by mass, and the color differences L * , a * and b * were 45.6, 0.2 and 8.4, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 36 mΩ · cm and 18 mΩ · cm, respectively.
［比較例２］
溶液２を３０分間かけて添加する代わりに５秒間で一挙に添加した以外は、比較例１と同様の方法により、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Comparative Example 2]
A silver-coated nickel powder (silver-coated nickel powder) was obtained by the same method as in Comparative Example 1 except that the solution 2 was added all at once in 5 seconds instead of being added over 30 minutes.
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．７２ｍ２／ｇ、タップ密度は４．７ｇ／ｃｍ３、酸素含有量は０．８０質量％、ＢＥＴ比表面積に対する酸素含有量は１．１１質量％・ｇ／ｍ２、炭素含有量は０．０２質量％であり、累積１０％粒子径（Ｄ１０）は１．１μｍ、累積５０％粒子径（Ｄ５０）は２．９μｍ、累積９０％粒子径（Ｄ９０）は７．３μｍであった。また、銀含有量（銀被覆量）は２０．４質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ４６．９、０．１および８．９であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ１１００ｍΩ・ｃｍおよび３１０ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.72 m 2 / g, the tap density was 4.7 g / cm 3 , the oxygen content was 0.80% by mass, and the oxygen content with respect to the BET specific surface area was 1.11. Mass% · g / m 2 , carbon content is 0.02 mass%, cumulative 10% particle size (D 10 ) is 1.1 μm, cumulative 50% particle size (D 50 ) is 2.9 μm, cumulative 90 The% particle size (D 90 ) was 7.3 μm. The silver content (silver coating amount) was 20.4% by mass, and the color differences L * , a * and b * were 46.9, 0.1 and 8.9, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 1100 mΩ · cm and 310 mΩ · cm, respectively.
また、実施例１〜６および比較例１〜２の銀被覆ニッケル粉末中の塩素含有量を求めたところ、いずれも１０ｐｐｍ未満であった。なお、銀被覆ニッケル粉末中の塩素含有量は、銀被覆ニッケル粉末１ｇと超純水１０ｍＬを秤量してフッ素樹脂製の容器に入れ、１２５℃で２０時間抽出して得られた抽出液を採取し、この抽出液を使用して、イオンクロマトグラフ（東ソー株式会社製のＩＣ−２０１０）により測定した。 Moreover, when the chlorine content in the silver-coated nickel powder of Examples 1 to 6 and Comparative Examples 1 and 2 was determined, it was less than 10 ppm in each case. Regarding the chlorine content in the silver-coated nickel powder, 1 g of the silver-coated nickel powder and 10 mL of ultrapure water were weighed and placed in a fluororesin container, and the extract obtained by extracting at 125 ° C. for 20 hours was collected. Then, using this extract, measurement was performed by an ion chromatograph (IC-2010 manufactured by Tosoh Corporation).
［比較例３］
水素還元を行わなかった以外は、実施例１と同様の方法により、ニッケル粉末を得た。このニッケル粉末２６０ｇを、４Ｌの純水が入った５Ｌのステンレスタンクに入れ、さらに５１．４ｍＬの希硝酸を加えて撹拌することにより、ニッケル粉末を酸洗した。この水溶液は、ニッケルの溶解により、薄い緑色になった。その後、薄い緑色の上澄みを除去し、純水でデカンテーションして、ニッケル粉末を洗浄して、乾燥させずに水中で保持し、ニッケル分散液とした。
このニッケル分散液を実施例１と同様の溶液１に加えて撹拌し、この溶液に実施例１と同様の溶液２を３０分間かけて添加して攪拌した後、固液分離し、水洗し、真空中において７０℃で１０時間乾燥し、解砕し、篩分して、銀により被覆されたニッケル粉末（銀被覆ニッケル粉末）を得た。
[Comparative Example 3]
Nickel powder was obtained by the same method as in Example 1 except that hydrogen reduction was not performed. 260 g of this nickel powder was placed in a 5 L stainless steel tank containing 4 L of pure water, and 51.4 mL of dilute nitric acid was further added and stirred to pickle the nickel powder. This aqueous solution turned pale green due to the dissolution of nickel. Then, the pale green supernatant was removed, decanted with pure water, the nickel powder was washed and held in water without drying to obtain a nickel dispersion.
This nickel dispersion is added to the same solution 1 as in Example 1 and stirred, and the same solution 2 as in Example 1 is added to this solution over 30 minutes and stirred, then solid-liquid separated, washed with water, and then washed. It was dried in vacuum at 70 ° C. for 10 hours, crushed and sieved to obtain a silver-coated nickel powder (silver-coated nickel powder).
このようにして得られた銀被覆ニッケル粉末について、実施例１と同様の方法により、ＢＥＴ比表面積、タップ密度、酸素含有量、炭素含有量、粒度分布、銀被覆量、色差（Ｌ＊、ａ＊、ｂ＊）および圧粉体抵抗を求めた。 With respect to the silver-coated nickel powder thus obtained, the BET specific surface area, tap density, oxygen content, carbon content, particle size distribution, silver coating amount, and color difference (L * , a) were obtained by the same method as in Example 1. * , B * ) and powder resistance were determined.
その結果、銀被覆ニッケル粉末のＢＥＴ比表面積は０．９０ｍ２／ｇ、タップ密度は４．０ｇ／ｃｍ３、酸素含有量は０．８０質量％、ＢＥＴ比表面積に対する酸素含有量は０．８９質量％・ｇ／ｍ２、炭素含有量は０．０２質量％であり、累積１０％粒子径（Ｄ１０）は１．２μｍ、累積５０％粒子径（Ｄ５０）は２．９μｍ、累積９０％粒子径（Ｄ９０）は７．２μｍであった。また、銀含有量（銀被覆量）は２０．７質量％であり、色差Ｌ＊、ａ＊およびｂ＊はそれぞれ４２．０、０．３および８．７であった。また、圧粉体抵抗として、銀被覆ニッケル粉末の圧粉体の体積抵抗率はそれぞれ２．２ｍΩ・ｃｍおよび１．５ｍΩ・ｃｍであった。 As a result, the BET specific surface area of the silver-coated nickel powder was 0.90 m 2 / g, the tap density was 4.0 g / cm 3 , the oxygen content was 0.80% by mass, and the oxygen content with respect to the BET specific surface area was 0.89. Mass% · g / m 2 , carbon content is 0.02 mass%, cumulative 10% particle size (D 10 ) is 1.2 μm, cumulative 50% particle size (D 50 ) is 2.9 μm, cumulative 90 The% particle size (D 90 ) was 7.2 μm. The silver content (silver coating amount) was 20.7% by mass, and the color differences L * , a * and b * were 42.0, 0.3 and 8.7, respectively. As the green compact resistance, the volume resistivity of the green compact of silver-coated nickel powder was 2.2 mΩ · cm and 1.5 mΩ · cm, respectively.
これらの実施例および比較例の銀被覆ニッケル粉末の製造条件および銀被覆前後のニッケル粉末の特性を表１〜表３に示す。 Tables 1 to 3 show the production conditions of the silver-coated nickel powders of these Examples and Comparative Examples and the characteristics of the nickel powders before and after the silver coating.
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