JP4978785B2 - Method for producing nickel powder - Google Patents
Method for producing nickel powder Download PDFInfo
- Publication number
- JP4978785B2 JP4978785B2 JP2007186221A JP2007186221A JP4978785B2 JP 4978785 B2 JP4978785 B2 JP 4978785B2 JP 2007186221 A JP2007186221 A JP 2007186221A JP 2007186221 A JP2007186221 A JP 2007186221A JP 4978785 B2 JP4978785 B2 JP 4978785B2
- Authority
- JP
- Japan
- Prior art keywords
- nickel
- powder
- particle size
- nickel powder
- roasting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Description
本発明は、ニッケル粉の製造方法に係り、より詳しくは積層セラミックコンデンサーの内部電極形成用として好適に用いることができるニッケル粉の製造方法に関する。 The present invention relates to a method for producing nickel powder, and more particularly to a method for producing nickel powder that can be suitably used for forming an internal electrode of a multilayer ceramic capacitor.
積層セラミックコンデンサー（以下、説明の便宜上「ＭＬＣＣ」と称する）は、誘電体層と内部電極を交互に積層させた構造を有し、小型高容量の優れたコンデンサーである。誘電体としては、チタン酸バリウムに代表されるセラミックス系材料が用いられている。一方、内部電極には、貴金属系材料が用いられていたが、近年においては、低コストであることからニッケル系材料を用いることが主流となっている。 A multilayer ceramic capacitor (hereinafter referred to as “MLCC” for convenience of explanation) is a small and high-capacity capacitor having a structure in which dielectric layers and internal electrodes are alternately stacked. As the dielectric, a ceramic material typified by barium titanate is used. On the other hand, noble metal-based materials have been used for the internal electrodes, but in recent years, nickel-based materials have become the mainstream because of their low cost.
ニッケル粉を内部電極形成用として用いるＭＬＣＣの製法の概略は、以下の通りである。
すなわち、誘電体のグリーンシートにニッケル粉と有機溶剤を種々の添加剤とともに混練して製造したニッケルペーストを印刷し、乾燥させる。次いで、これを所望数積層し、熱圧着した後にチップ形状に切断し、切断後、３００℃程度の温度で脱バインダーを行った後、内部電極と誘電体グリーンシートを千数百度の温度で焼結し、ニッケルなどによる外部電極を形成する。
The outline of the production method of MLCC using nickel powder for internal electrode formation is as follows.
That is, a nickel paste produced by kneading nickel powder and an organic solvent together with various additives is printed on a dielectric green sheet and dried. Next, a desired number of layers are stacked, thermocompression bonded, cut into a chip shape, and after cutting, the binder is removed at a temperature of about 300 ° C., and then the internal electrode and the dielectric green sheet are baked at a temperature of several thousand hundred degrees. As a result, an external electrode made of nickel or the like is formed.
脱バインダー工程は、酸化雰囲気中での熱処理によりバインダーを燃焼させる方法が行われている。誘電体グリーンシートのバインダーには、ポリビニルアルコール系の物質が用いられることが多く、内部電極形成用のニッケルペーストのバインダーにはエチルセルロース系の物質が用いられることが多い。両者の燃焼タイミング、発生ガス量を制御する形で、脱バインダー工程での雰囲気、温度が調整されている。 In the binder removal step, a method of burning the binder by heat treatment in an oxidizing atmosphere is performed. A polyvinyl alcohol-based material is often used as the binder of the dielectric green sheet, and an ethylcellulose-based material is often used as the binder of the nickel paste for forming the internal electrode. The atmosphere and temperature in the debinding process are adjusted so as to control the combustion timing and the amount of generated gas.
ニッケル粉には、この工程にて意図しないガス発生を生じさせたり、酸化による顕著な体積変化が生じたりしないようにすることが求められ、その製造工程にて純度を厳密に制御され、表面状態が調整されている。また、誘電体はセラミックであり、内部電極は金属であることから、一般的に、焼結時の収縮量は内部電極の方が大きい。また、融点も金属のほうが低いことから、焼結開始温度も内部電極の方が低い。したがって、ニッケルペーストにはセラミック粉末などを混合して焼結現象を遅延させたり、また、ニッケル粉そのものに他の元素を微量に添加したりすることで同効果を得ることがなされている。 Nickel powder is required not to cause unintentional gas generation in this process or to cause a significant volume change due to oxidation. Has been adjusted. In addition, since the dielectric is a ceramic and the internal electrode is a metal, the shrinkage during sintering is generally larger in the internal electrode. In addition, since the melting point of the metal is lower, the sintering start temperature is lower for the internal electrode. Therefore, the same effect can be obtained by mixing ceramic powder or the like in the nickel paste to delay the sintering phenomenon, or adding a small amount of other elements to the nickel powder itself.
一方、ＭＬＣＣメーカーでは、ＭＬＣＣの更なる小型化、高容量化を目指し、内部電極および誘電体厚みの薄層化、高積層化を進めている。薄層化された内部電極では、ニッケル粉の粒径が大きいと電極厚み方向に存在する粒子数が少なく、また、粒子間の空隙も大きくなることから、焼結後の電極に穴開きや途切れが発生して電極として機能しなくなる。このため、内部電極に用いられるニッケル粉においてもさらに微細な粒径のものが求められている。また、薄層化されたＭＬＣＣにおいては、粗大なニッケル粉が混入していると電極間のショートが発生するため、粗大粒子が含まれないことが要求されている。さらに、平均粒径より大幅に細かい粒子が存在すると脱バインダー工程での酸化、焼結工程での焼結開始温度の低温化が生じるため、極端に粒径の細かい粒子が含まれないことも重要である。 On the other hand, MLCC manufacturers are working to reduce the thickness and increase the thickness of internal electrodes and dielectrics with the aim of further reducing the size and increasing the capacity of MLCCs. In the thinned internal electrode, if the particle size of the nickel powder is large, the number of particles existing in the electrode thickness direction is small, and the voids between the particles are also large. Occurs and does not function as an electrode. For this reason, the nickel powder used for the internal electrode is also required to have a finer particle size. Further, in the MLCC having a thin layer, when coarse nickel powder is mixed, a short circuit occurs between the electrodes, and it is required that coarse particles are not included. Furthermore, if particles that are significantly finer than the average particle size are present, oxidation in the binder removal process and lowering of the sintering start temperature in the sintering process occur, so it is also important that particles with extremely fine particle sizes are not included. It is.
以上のように、内部電極用ニッケル粉に対しては、脱バインダー工程でガスを発生し難いこと、誘電体の焼結収縮特性に近いことなども求められているが、微細で均一な粒径であることが最も重要な要求特性となっている。 As described above, the nickel powder for internal electrodes is required to be less likely to generate gas in the debinding process and close to the sintering shrinkage characteristics of the dielectric. Is the most important requirement.
上記問題を解決するため、種々の方法で製造された微細で粗大粒子を含まないニッケル粉が提案されている。
例えば、特許文献１では、塩化ニッケル蒸気の気相水素還元法による平均粒径が０．２〜０．６μｍであり、かつ平均粒径の２．５倍以上の粒径をもつ粗粒子の存在率が個数基準で０．１％以下としたニッケル粉が提案されている。また、特許文献２においては、平均粒径が０．１〜１．０μｍのニッケル粉であって、粒径２μｍ以上のニッケル粉の含有率が個数基準で７００／１００万以下であるニッケル粉が、塩化ニッケル蒸気の気相水素還元法等で得たニッケル粉を液体サイクロン等で分級することで得られることが開示されている。さらに、特許文献３においては、レーザ回折散乱式粒度分布測定による平均粒径の１．５倍以上の粒子径を持つ粒子個数が全粒子個数の２０％以下であり、平均粒子径の０．５倍以下の粒子径を持つ粒子個数が全粒子個数の５％以下であり、ＳＥＭ観察による平均一次粒子径が０．１〜２μｍであるニッケル粉が提案されている。このニッケル粉は、ニッケル塩を原料として水溶液中で還元処理する湿式法等により得られた凝集体を含むニッケル粉を原粉として用いて解粒処理によって得られるものである。
In order to solve the above problems, nickel powders produced by various methods and containing no coarse particles have been proposed.
For example, in Patent Document 1, the presence of coarse particles having an average particle size of 0.2 to 0.6 μm by vapor phase hydrogen reduction of nickel chloride vapor and having a particle size of 2.5 times or more the average particle size Nickel powder with a rate of 0.1% or less on the number basis has been proposed. Moreover, in patent document 2, it is nickel powder with an average particle diameter of 0.1-1.0 micrometer, Comprising: The nickel powder whose content rate of nickel powder with a particle diameter of 2 micrometers or more is 700/1 million or less on a number basis. It is disclosed that nickel powder obtained by vapor phase hydrogen reduction of nickel chloride vapor can be obtained by classification with a liquid cyclone or the like. Further, in Patent Document 3, the number of particles having a particle size of 1.5 times or more of the average particle size measured by laser diffraction scattering type particle size distribution measurement is 20% or less of the total particle number, and the average particle size is 0.5%. Nickel powder has been proposed in which the number of particles having a particle size of twice or less is 5% or less of the total number of particles, and the average primary particle size by SEM observation is 0.1 to 2 μm. This nickel powder is obtained by a pulverization treatment using a nickel powder containing an aggregate obtained by a wet process in which a nickel salt is used as a raw material in an aqueous solution and the like as a raw powder.
しかしながら、これらの提案で得られるニッケル粉は、いずれもコストが高くなるという問題がある。気相水素還元法で得られるニッケル粉は結晶性もよく特性面で優れるが、生産性が低くコスト高となる。また、気相水素還元法等で得たニッケル粉を分級することは、歩留が悪化してより高コストとなる。湿式法等により得られた凝集体を解粒処理しても、解粒前の一次粒子径が均一でなければ分級する必要があり、歩留悪化による高コスト化は避けられない。湿式法で製造すると粒子径が比較的均一なニッケル粉が得られるが、生産性が低くコスト高となる問題は解決されない。 However, the nickel powder obtained by these proposals has a problem that the cost becomes high. Nickel powder obtained by the gas phase hydrogen reduction method has good crystallinity and excellent characteristics, but has low productivity and high cost. Moreover, classifying nickel powder obtained by a gas phase hydrogen reduction method or the like results in a worse yield and higher cost. Even if the agglomerates obtained by a wet method or the like are pulverized, if the primary particle diameter before pulverization is not uniform, it is necessary to classify, and an increase in cost due to deterioration in yield is inevitable. When manufactured by a wet method, nickel powder having a relatively uniform particle size can be obtained, but the problem of low productivity and high cost cannot be solved.
一方、低コストなニッケル粉としては、水酸化ニッケルの加熱還元によって得られるニッケル粉が挙げられる。例えば、特許文献４には、反応槽内のスラリーに、含ニッケル溶液を連続的に添加しつつ、アルカリ溶液を添加して水酸化ニッケルを生成させ、該スラリーを濾過し、水洗し、乾燥して水酸化ニッケルを得、これを還元剤として水素を用い、還元温度を４００〜５５０℃として加熱還元することによりニッケル粉を得る製造方法が開示されている。しかしながら、水酸化ニッケルの加熱還元によって得られるニッケル粉は大量生産が可能で低コストであるが、微細で均一な粒径のニッケル粉が得難いという問題点があった。 On the other hand, the low-cost nickel powder includes nickel powder obtained by heat reduction of nickel hydroxide. For example, in Patent Document 4, while adding a nickel-containing solution continuously to a slurry in a reaction vessel, an alkaline solution is added to form nickel hydroxide, and the slurry is filtered, washed with water, and dried. Thus, there is disclosed a production method for obtaining nickel powder by obtaining nickel hydroxide, using hydrogen as a reducing agent, and heating and reducing at a reduction temperature of 400 to 550 ° C. However, nickel powder obtained by heat reduction of nickel hydroxide can be mass-produced and is low in cost, but there is a problem that it is difficult to obtain nickel powder having a fine and uniform particle size.
以上のように、微細で均一な粒径のニッケル粉を大量に低コストで製造する方法は、未だ開発されていないのが実状である。
本発明は、前記した従来の実状に鑑みてなされたもので、微細で均一な粒径を持ったニッケル粉を大量に低コストで製造する方法を提供することを目的とするものである。 The present invention has been made in view of the above-described conventional situation, and an object of the present invention is to provide a method for producing a large amount of nickel powder having a fine and uniform particle size at a low cost.
本発明者は、上記問題点を解決するため、水酸化ニッケルを加熱還元してニッケル粉を得る方法について鋭意研究を行なったところ、特定条件で水酸化ニッケルの焙焼を行なって酸化ニッケルを得ること、得られた酸化ニッケルを特定条件で加熱還元することにより、微細で均一な粒径のニッケル粉が低コストで得られることを知見し、本発明を見出した。
すなわち、本発明に係るニッケル粉の製造方法は、アルカリ土類金属を０．００２〜１質量％含む水酸化ニッケル粉を焙焼して酸化ニッケル粉とし、得られた酸化ニッケル粉を還元するニッケル粉の製造方法において、水酸化ニッケル１ｇに対して０．０２〜０．４リットル/分の空気を流すとともに２５０〜５００℃の温度で焙焼して水酸化ニッケル粉を酸化ニッケル粉とし、さらに得られた酸化ニッケル粉を酸化ニッケル粉１ｇに対して０．０１〜０．２リットル/分の水素を流すとともに３００〜５００℃の温度で還元してニッケル粉とすることを特徴とするものである。
In order to solve the above problems, the present inventor conducted extensive research on a method for obtaining nickel powder by heat reduction of nickel hydroxide. Nickel oxide is obtained by roasting nickel hydroxide under specific conditions. In addition, the present inventors have found that a nickel powder having a fine and uniform particle diameter can be obtained at low cost by heating and reducing the obtained nickel oxide under specific conditions.
That is, the nickel powder manufacturing method according to the present invention is a nickel hydroxide powder obtained by roasting nickel hydroxide powder containing 0.002 to 1% by mass of alkaline earth metal, and reducing the obtained nickel oxide powder. In the powder production method, 0.02 to 0.4 liter / min of air is flowed with respect to 1 g of nickel hydroxide and roasted at a temperature of 250 to 500 ° C. to change the nickel hydroxide powder to nickel oxide powder. The obtained nickel oxide powder is made to flow into the nickel powder by flowing 0.01 to 0.2 liter / min of hydrogen with respect to 1 g of the nickel oxide powder and reducing it to a temperature of 300 to 500 ° C. is there.
また、本発明の前記焙焼によって得られる酸化ニッケルは、還元雰囲気中で加熱したときの質量減少が下記条件を満たすことが好ましい。
記
０．５≦(室温〜４００℃の減量(質量％))／(室温〜８００℃の減量(質量％))≦１
Moreover, it is preferable that the nickel oxide obtained by the said baking of this invention satisfy | fills the following conditions for the mass reduction | decrease when heated in a reducing atmosphere.
0.5 ≦ (weight loss from room temperature to 400 ° C. (mass%)) / (weight loss from room temperature to 800 ° C. (mass%)) ≦ 1
さらに、本発明に係るニッケル粉の製造方法においては、水酸化ニッケル粉に含有されるアルカリ土類金属は、マグネシウムであることが好ましく、またさらに、本発明に係るニッケル粉の製造方法においては、得られるニッケル粉の平均粒径が０．２〜０．４μｍであることが好ましい。 Furthermore, in the method for producing nickel powder according to the present invention, the alkaline earth metal contained in the nickel hydroxide powder is preferably magnesium, and furthermore, in the method for producing nickel powder according to the present invention, It is preferable that the average particle diameter of the obtained nickel powder is 0.2 to 0.4 μm.
本発明は、水酸化ニッケルを加熱還元してニッケル粉を得る方法において、特定条件で水酸化ニッケルの焙焼を行なって酸化ニッケルを得ると共に、得られた酸化ニッケルを特定条件で加熱還元することにより、微細で均一な粒径のニッケル粉を大量に低コストで製造することができるという優れた効果を奏する。また、本発明法により得られるニッケル粉は、特に小型化、高容量化が進むＭＬＣＣ内部電極形成用として好適なものであり、工業的価値が極めて大きい。 In the method of obtaining nickel powder by heating and reducing nickel hydroxide, the present invention obtains nickel oxide by baking nickel hydroxide under specific conditions, and heat-reducing the obtained nickel oxide under specific conditions. As a result, the nickel powder having a fine and uniform particle diameter can be produced in a large amount at a low cost. In addition, the nickel powder obtained by the method of the present invention is particularly suitable for forming MLCC internal electrodes whose size and capacity are increasing, and has an extremely large industrial value.
本発明のニッケル粉の製造方法においては、水酸化ニッケルの焙焼条件および酸化ニッケルの還元条件が重要である。本発明においては、酸化ニッケル粉を低温、短時間で還元を完了させることにより、所望の粒径で均一なニッケル粉を得ている。このように、低温、短時間で還元させるためには、結晶性が低く粒径が細かく、還元されやすい酸化ニッケルを用いることが必要である。
本発明において、水酸化ニッケル１ｇに対して０．０２〜０．４リットル／分の空気を流すとともに２５０〜５００℃の温度で焙焼して得られた水酸化ニッケル粉を酸化ニッケル粉とし、さらに得られた酸化ニッケル粉を当該酸化ニッケル粉１ｇに対して０．０１〜０．２リットル／分の水素を流すとともに３００〜５００℃の温度で還元してニッケル粉とするのは、以下に記載する理由による。
まず、アルカリ土類金属を含む水酸化ニッケル粉を水酸化ニッケル１ｇに対して０．０２〜０．４リットル／分の空気を流すとともに２５０〜５００℃の温度で焙焼して酸化ニッケル粉を得るのは、焙焼時に流す空気量が、水酸化ニッケル１ｇに対して０．０２リットル／分未満であると、水酸化ニッケルの酸化ニッケルへの分解が徐々に進むために、酸化ニッケルの結晶が成長し、他方、５００℃を超える温度で焙焼すると、焙焼中に焼結が進み粗大な酸化ニッケル粉となってしまう。
このようにして得られた酸化ニッケルは、結晶が成長しているか粗大な粒径となっているため、還元するためには高温で、かつ長時間還元させる必要が生じてしまう。高温で、かつ長時間の還元を行なった場合には、ニッケル粉の粒成長が進み、粗大で粒径が不均一なものとなってしまう。
焙焼時に流す空気量が、水酸化ニッケル１ｇに対して０．４リットル／分を超えても均一微細なニッケル粉を得る効果は得られるが、その効果に更なる改善はなく、コスト増となるのみである。また、多量の空気を流すと微細な酸化ニッケル粉が飛散して歩留も低下する。一方、焙焼温度が２５０℃未満では、焙焼に長時間要するのみならず水酸化ニッケルから酸化ニッケルへの転換が十分に進まず還元時に還元が不均一に進むためニッケル粉の粒成長が起こる。
焙焼時間は特に限定されるものではなく、焙焼時に流す空気量、焙焼温度、投入する水酸化ニッケル粉の量により、全ての水酸化ニッケルが酸化ニッケルに転換されるのに必要な時間とすればよい。このとき、結晶性を低くするため、焙焼時間は、可能な限り短時間とすることが好ましい。
In the method for producing nickel powder of the present invention, roasting conditions for nickel hydroxide and reducing conditions for nickel oxide are important. In the present invention, the nickel oxide powder is completely reduced at a low temperature for a short time to obtain a uniform nickel powder having a desired particle size. Thus, in order to reduce at a low temperature for a short time, it is necessary to use nickel oxide that has low crystallinity, a small particle size, and is easily reduced.
In the present invention, nickel hydroxide powder obtained by flowing air at 0.02 to 0.4 liter / min to 1 g of nickel hydroxide and roasting at a temperature of 250 to 500 ° C. is used as nickel oxide powder. Furthermore, the obtained nickel oxide powder is made to flow into the nickel powder by flowing 0.01 to 0.2 liter / min of hydrogen with respect to 1 g of the nickel oxide powder and reducing it to a temperature of 300 to 500 ° C. It depends on the reason described.
First, nickel hydroxide powder containing alkaline earth metal is roasted at a temperature of 250 to 500 ° C. while flowing air of 0.02 to 0.4 liter / min with respect to 1 g of nickel hydroxide to obtain nickel oxide powder. Since the decomposition of nickel hydroxide into nickel oxide gradually proceeds when the amount of air flowing during roasting is less than 0.02 liter / min with respect to 1 g of nickel hydroxide, crystals of nickel oxide are obtained. On the other hand, when roasting at a temperature exceeding 500 ° C., sintering proceeds during roasting and coarse nickel oxide powder is formed.
Since the nickel oxide obtained in this way has grown crystals or has a coarse particle size, it needs to be reduced at a high temperature for a long time in order to reduce it. When reduction is performed at a high temperature for a long time, the grain growth of nickel powder proceeds, resulting in a coarse and non-uniform particle size.
Even if the amount of air flowing at the time of roasting exceeds 0.4 liter / min with respect to 1 g of nickel hydroxide, an effect of obtaining uniform fine nickel powder can be obtained, but there is no further improvement in the effect, and the cost increases. It only becomes. In addition, when a large amount of air is flowed, fine nickel oxide powder is scattered and the yield is also lowered. On the other hand, when the roasting temperature is less than 250 ° C., not only does roasting take a long time, but also the conversion from nickel hydroxide to nickel oxide does not proceed sufficiently, and the reduction proceeds non-uniformly during reduction, resulting in the growth of nickel powder grains. .
The roasting time is not particularly limited, and the time required for all the nickel hydroxide to be converted to nickel oxide depending on the amount of air flowing during roasting, the roasting temperature, and the amount of nickel hydroxide powder to be added. And it is sufficient. At this time, in order to lower the crystallinity, the baking time is preferably as short as possible.
次に、このようにして得られた酸化ニッケルを、水素を含む雰囲気下で還元する際、酸化ニッケル１ｇに対して０．０１〜０．２リットル／分の水素を流し、３００〜５００℃の温度で還元する。このとき、水素ガスのみを流してもよく、水素ガスと窒素などの不活性ガスとの混合ガスを流してもよい。ここで、還元時に流す水素量が酸化ニッケル１ｇに対して０．０１リットル／分未満の場合は、還元が徐々に進むためにニッケル粉の粒成長が起こり、所望の粒径で均一なニッケル粉が得られず、他方、水素量が酸化ニッケル１ｇに対して０．２リットル／分を超えても、微細で均一な粒径のニッケル粉を得るために必要である還元を短時間化する効果の改善がなく、無駄な水素が増えコスト増となるのみである。
また、還元温度を３００〜５００℃と限定したのは、還元温度が５００℃を超えると、還元されたニッケル粉が還元中に焼結し、結果として所望の粒径を精度良く得ることができず、他方、３００℃未満の温度では、酸化ニッケルからニッケルへの還元が進みにくく、還元に長時間が必要となりニッケル粉の凝集が進んでしまうためである。
なお、還元時間は特に限定されるものではなく、還元時に流す水素量、還元温度、投入する酸化ニッケル粉の量により、全ての酸化ニッケルがニッケルに還元されるのに必要な時間とすればよく、所望の粒径が得られるように時間を制御することが好ましい。また、焙焼および還元に用いる設備は、雰囲気を制御できれば特に制限はなく、例えば、バッチ式雰囲気炉、バッチ式ロータリーキルン、連続式ローラーハースキルン、連続式プッシャー炉、連続式ロータリーキルンなどを用いることができる。
Next, when the nickel oxide thus obtained is reduced in an atmosphere containing hydrogen, 0.01 to 0.2 liter / min of hydrogen is allowed to flow with respect to 1 g of nickel oxide at a temperature of 300 to 500 ° C. Reduce at temperature. At this time, only hydrogen gas may flow or a mixed gas of hydrogen gas and an inert gas such as nitrogen may flow. Here, when the amount of hydrogen flowing at the time of reduction is less than 0.01 liter / min with respect to 1 g of nickel oxide, grain reduction of nickel powder occurs because the reduction proceeds gradually, and uniform nickel powder with a desired particle diameter On the other hand, even if the amount of hydrogen exceeds 0.2 liter / min with respect to 1 g of nickel oxide, the effect of shortening the reduction necessary for obtaining a fine and uniform particle size of nickel powder However, there is no improvement in the amount of wasteful hydrogen, which only increases costs.
Moreover, the reduction temperature is limited to 300 to 500 ° C. When the reduction temperature exceeds 500 ° C., the reduced nickel powder is sintered during the reduction, and as a result, a desired particle size can be obtained with high accuracy. On the other hand, at a temperature lower than 300 ° C., the reduction from nickel oxide to nickel is difficult to proceed, and a long time is required for the reduction, and the aggregation of the nickel powder proceeds.
The reduction time is not particularly limited, and may be a time required for all the nickel oxide to be reduced to nickel depending on the amount of hydrogen flowing during reduction, the reduction temperature, and the amount of nickel oxide powder to be added. It is preferable to control the time so that a desired particle size is obtained. The equipment used for roasting and reduction is not particularly limited as long as the atmosphere can be controlled. For example, a batch type atmospheric furnace, a batch type rotary kiln, a continuous roller hearth kiln, a continuous type pusher furnace, a continuous type rotary kiln, etc. may be used. it can.
本発明に係るニッケル粉の製造方法においては、上記焙焼によって得られる酸化ニッケルが、還元雰囲気中で加熱したときの質量減少が前記条件、すなわち０．５≦(室温〜４００℃の減量(質量％))／(室温〜８００℃の減量(質量％))≦１を満たすことが好ましい。 In the method for producing nickel powder according to the present invention, the nickel oxide obtained by the roasting has the mass reduction when heated in a reducing atmosphere as described above, that is, the weight loss of 0.5 ≦ (room temperature to 400 ° C. (mass %)) / (Weight loss from room temperature to 800 ° C. (mass%)) ≦ 1 is preferably satisfied.
本発明において、前記還元雰囲気中で加熱したときの質量減少は、還元により減少した酸化ニッケル中の酸素の量を示すものであり、室温〜８００℃の減量（質量％）は、完全に還元した時の酸素含有量であり、室温〜４００℃の減量（質量％）は、４００℃以下で還元される酸素含有量を示す。すなわち、(室温〜４００℃の減量(質量％))／(室温〜８００℃の減量(質量％))の比（以下、熱減量比）は、４００℃以下で還元される酸化ニッケルの比率を示すものである。 In the present invention, the mass reduction when heated in the reducing atmosphere indicates the amount of oxygen in the nickel oxide reduced by the reduction, and the weight loss (% by mass) from room temperature to 800 ° C. was completely reduced. The oxygen content at the time, and the weight loss (mass%) from room temperature to 400 ° C. indicates the oxygen content reduced at 400 ° C. or less. That is, the ratio of (weight loss from room temperature to 400 ° C. (mass%)) / (weight loss from room temperature to 800 ° C. (mass%)) (hereinafter referred to as heat loss ratio) is the ratio of nickel oxide reduced at 400 ° C. or less. It is shown.
本発明に係るニッケル粉の製造方法は、低温で還元を行なうことを特徴とするものであり、前記条件を満たす酸化ニッケルは、低温で還元が可能であることを示している。したがって、熱減量比は、０．５〜１であることが好ましい。すなわち、熱減量比が０．５未満であると、４００℃を超える温度で還元される酸化ニッケル粉が多くなり、還元により得られるニッケル粉の粒成長が進み、粗大で粒径が不均一なものとなることがある。したがって、４００℃以下の温度で還元される酸化ニッケルが多い方が好ましく、全ての酸化ニッケルが還元されても問題がないため、熱減量比が１までの範囲を採ることができる。
なお、熱減量比を測定する場合の還元雰囲気は特に限定されるものではなく、例えば、２容量％水素−窒素混合ガスなどの還元ガスと不活性ガスとの混合ガスが用いられる。また、測定に用いられる装置も通常に用いられる熱分析装置でよく、測定条件も通常の測定で推奨される条件でよい。
The method for producing nickel powder according to the present invention is characterized in that reduction is performed at a low temperature, and nickel oxide that satisfies the above conditions can be reduced at a low temperature. Accordingly, the heat loss ratio is preferably 0.5 to 1. That is, when the thermal weight loss ratio is less than 0.5, the amount of nickel oxide powder reduced at a temperature exceeding 400 ° C. increases, and the grain growth of the nickel powder obtained by reduction proceeds, which is coarse and uneven in particle size. It can be a thing. Accordingly, it is preferable that the amount of nickel oxide reduced at a temperature of 400 ° C. or less is large, and even if all nickel oxide is reduced, there is no problem, and thus the heat loss ratio can be in a range up to 1.
In addition, the reducing atmosphere in the case of measuring a heat loss ratio is not specifically limited, For example, the mixed gas of reducing gas and inert gas, such as 2 volume% hydrogen-nitrogen mixed gas, is used. Moreover, the apparatus used for the measurement may be a commonly used thermal analysis apparatus, and the measurement conditions may be those recommended for normal measurement.
本発明に係るニッケル粉の製造方法において用いられる水酸化ニッケル粉は、通常の公知の方法により得ることができる。例えば、塩化ニッケルや硫酸ニッケルなどの水溶性ニッケル塩の水溶液をｐＨ制御して中和沈殿させることで得られる水酸化ニッケル粉を用いることができる。水酸化ニッケル粉に含有されるアルカリ土類金属は、水溶性塩などの水溶性物質としてニッケル塩水溶液に混合しておき、水酸化ニッケルの生成時に共沈させてやればよい。水酸化ニッケル粉を製造する反応設備に特に制限はなく、通常用いられる設備でよく、例えば、攪拌機を有する貯槽でｐＨ管理が行なえるものであればよい。 The nickel hydroxide powder used in the method for producing nickel powder according to the present invention can be obtained by an ordinary known method. For example, nickel hydroxide powder obtained by neutralizing and precipitating an aqueous solution of a water-soluble nickel salt such as nickel chloride or nickel sulfate by pH control can be used. The alkaline earth metal contained in the nickel hydroxide powder may be mixed with a nickel salt aqueous solution as a water-soluble substance such as a water-soluble salt and coprecipitated when nickel hydroxide is produced. There is no particular limitation on the reaction equipment for producing the nickel hydroxide powder, and any equipment that is normally used may be used, for example, as long as the pH can be controlled in a storage tank having a stirrer.
前記水酸化ニッケル粉に含有されるアルカリ土類金属は、還元時におけるニッケル粒子生成時の粒子の微細化および球状化、さらには粒子表面の平滑性改善に効果がある。水酸化ニッケル中のアルカリ土類金属の含有量は、０．００２〜１質量％とする。アルカリ土類金属が、０．００２質量％未満の場合には、微細化および平滑性改善の効果が見られない。アルカリ土類金属が１質量％を超えた場合には、得られるニッケル粉のニッケル品位の低下により、ＭＬＣＣ内部電極として用いられた場合に、電極の電気抵抗値が大きくなり過ぎ、コンデンサーの損失係数の悪化を招く。 The alkaline earth metal contained in the nickel hydroxide powder is effective in reducing the size and spheroidization of the particles when the nickel particles are produced during the reduction, and further improving the smoothness of the particle surface. The content of alkaline earth metal in nickel hydroxide is 0.002 to 1% by mass. When the alkaline earth metal is less than 0.002% by mass, the effect of refinement and improvement in smoothness is not observed. When the alkaline earth metal content exceeds 1% by mass, the electrical resistance of the electrode becomes too large when used as an MLCC internal electrode due to the decrease in nickel quality of the resulting nickel powder, and the loss factor of the capacitor Invite the deterioration.
前記水酸化ニッケルの焙焼と還元によって得られたニッケル粉は、粒径が微細でかつ均一であり粒子間の凝集も非常に少ないものであるが、工程中に生成した凝集粉の解砕あるいは工程中に混入した異物を除去する目的から、乾式または湿式による遠心力やフィルターを用いた解砕や分級を行なってもよい。用いられる装置は特に限定されるものではなく、通常のニッケル粉の製造に用いられるジェットミルやサイクロン形式の装置が使用される。 The nickel powder obtained by roasting and reduction of the nickel hydroxide has a fine and uniform particle size and very little aggregation between the particles. For the purpose of removing foreign substances mixed in the process, crushing or classification using a dry or wet centrifugal force or a filter may be performed. The apparatus to be used is not particularly limited, and a jet mill or a cyclone type apparatus that is used for producing ordinary nickel powder is used.
以上のような本発明に係るニッケル粉の製造方法で得られるニッケル粉は、平均粒径が０．２〜０．４μｍであることが好ましい。すなわち、平均粒径が０．２μｍ未満であると、ＭＬＣＣ内部電極用ペーストとして用いたとき、ニッケル粉の焼結温度が低いため、誘電体セラミックスとの焼結挙動の差が大きく、電極の途切れや剥離が起こることがあり、他方、平均粒径が０．４μｍを超えると、薄層化された内部電極では、焼結後の電極に穴開きや途切れが発生することがあり好ましくないためである。
［実施例］
The nickel powder obtained by the method for producing nickel powder according to the present invention as described above preferably has an average particle size of 0.2 to 0.4 μm. That is, when the average particle size is less than 0.2 μm, when used as a paste for MLCC internal electrodes, the sintering temperature of nickel powder is low, so the difference in sintering behavior with dielectric ceramics is large, and the electrodes are interrupted. On the other hand, if the average particle diameter exceeds 0.4 μm, the thinned internal electrode may cause holes or breaks in the sintered electrode, which is not preferable. is there.
[Example]
以下に、本発明の実施例を用いて詳細に説明するが、本発明は、これらの実施例によって何ら限定されるものではない。なお、ニッケル粉の評価は以下のようにして行なった。
（１）粒径：走査型電子顕微鏡（ＪＳＭ−５５１０、日本電子製）で１０，０００倍の写真を撮影し、写真一視野で確認できる全ての粒子の粒径を測定して統計処理した。評価項目は、篩下１０％相当径（Ｄ１０）、篩下５０％相当径（Ｄ５０：平均径）、篩下９０％相当径（Ｄ９０）とした。
（２）熱減量比：熱分析装置（ＴＧ−ＤＴＡ２０００ＳＡ、ＭＡＣ製）を用い、２容量％水素−窒素混合ガス雰囲気中において１０℃／分の昇温速度で室温からの８００℃までの熱重量変化を測定し、(４００℃までの減量(質量％))／(８００℃までの減量(質量％))の計算を行って求めた。
Hereinafter, the present invention will be described in detail using examples, but the present invention is not limited to these examples. The nickel powder was evaluated as follows.
(1) Particle size: A 10,000 times photograph was taken with a scanning electron microscope (JSM-5510, manufactured by JEOL), and the particle size of all the particles that could be confirmed in one field of view was measured and statistically processed. The evaluation items were 10% equivalent diameter under sieve (D10), 50% equivalent diameter under sieve (D50: average diameter), and 90% equivalent diameter under sieve (D90).
(2) Thermal weight loss ratio: Thermal weight from room temperature to 800 ° C. at a heating rate of 10 ° C./min in a 2% by volume hydrogen-nitrogen mixed gas atmosphere using a thermal analyzer (TG-DTA2000SA, manufactured by MAC). The change was measured and calculated by calculating (weight loss up to 400 ° C. (mass%)) / (weight reduction up to 800 ° C. (mass%)).
１００ｇの塩化ニッケル６水和物（試薬１級、和光純薬製）と塩化マグネシウム６水和物（試薬１級、和光純薬製）０．２ｇ（水酸化ニッケル中Ｍｇ含有量０．０６質量％相当）を純水２５０ｍＬに溶解して塩化ニッケル水溶液を調製した。次いで、水酸化ナトリウム（試薬１級、和光純薬製）３５．５ｇを純水２５０ｍＬに溶解した溶液を前記塩化ニッケル水溶液に添加し、生成した水酸化物をろ過した。さらに、これを１Ｌの純水で水洗し、再びろ過した（以下、本操作を「ろ過水洗」と呼ぶ）。同様にろ過水洗を４回繰り返した後に、箱型大気乾燥機（ＤＸ６０１、ヤマト科学製）で１５０℃、４８時間の乾燥を行い、水酸化ニッケルを得た。
得られた水酸化ニッケルを解砕した後、バッチ式雰囲気炉（管状炉、入江製作所製）を用いて乾燥水酸化ニッケル粉１ｇあたり空気流量を０．２リットル／分とし、４５０℃で６時間保持して焙焼して酸化ニッケル粉を得た。
得られた酸化ニッケル粉について熱分析装置により熱減量比を求めた。さらに、酸化ニッケル粉を、酸化ニッケル粉１ｇあたり０．１リットル／分の水素ガスと同量の窒素ガスを混合して流したバッチ式雰囲気炉中に４５０℃で１時間保持してニッケル粉を得た。得られたニッケル粉を＃１００の篩にかけ、そのニッケル粉の粒径を走査型電子顕微鏡（以下、ＳＥＭ）により測定した。
水酸化ニッケル中のＭｇ添加量、焙焼条件および還元条件、熱減量比、粒径測定結果をまとめて表１に示す。
100 g of nickel chloride hexahydrate (reagent grade 1, manufactured by Wako Pure Chemical Industries) and magnesium chloride hexahydrate (reagent grade 1, manufactured by Wako Pure Chemical Industries) 0.2 g (Mg content in nickel hydroxide: 0.06 mass) %) Was dissolved in 250 mL of pure water to prepare an aqueous nickel chloride solution. Next, a solution obtained by dissolving 35.5 g of sodium hydroxide (reagent grade 1, manufactured by Wako Pure Chemical Industries, Ltd.) in 250 mL of pure water was added to the nickel chloride aqueous solution, and the generated hydroxide was filtered. Further, this was washed with 1 L of pure water and filtered again (hereinafter, this operation is referred to as “filtered water washing”). Similarly, after washing with filtered water four times, drying was performed at 150 ° C. for 48 hours with a box-type atmospheric dryer (DX601, manufactured by Yamato Kagaku) to obtain nickel hydroxide.
After pulverizing the obtained nickel hydroxide, the air flow rate was 0.2 liter / min per 1 g of dried nickel hydroxide powder using a batch-type atmosphere furnace (tubular furnace, manufactured by Irie Seisakusho) at 450 ° C. for 6 hours. The nickel oxide powder was obtained by holding and baking.
The heat loss ratio of the obtained nickel oxide powder was determined by a thermal analyzer. Further, the nickel oxide powder is held at 450 ° C. for 1 hour in a batch type atmosphere furnace in which the same amount of nitrogen gas as 0.1 liter / min of nickel oxide powder is mixed and flowed for 1 hour. Obtained. The obtained nickel powder was passed through a # 100 sieve, and the particle size of the nickel powder was measured with a scanning electron microscope (hereinafter, SEM).
Table 1 summarizes the Mg addition amount in nickel hydroxide, roasting conditions and reduction conditions, heat loss ratio, and particle size measurement results.
塩化ニッケル水溶液に添加する塩化マグネシウム６水和物を０．１ｇ（水酸化ニッケル中Ｍｇ含有量０．０２質量％相当）とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
A nickel powder was obtained in the same manner as in Example 1 except that 0.1 g of magnesium chloride hexahydrate added to the nickel chloride aqueous solution was changed to 0.1 g (equivalent to Mg content of 0.02 mass% in nickel hydroxide). The particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
焙焼条件を２８０℃で４８時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the roasting conditions were changed to 280 ° C. for 48 hours, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
焙焼条件を４９０℃で２時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the roasting conditions were 490 ° C. for 2 hours, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
焙焼時に流す空気流量を０．０２リットル／分とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the air flow rate during roasting was set to 0.02 liter / min, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
焙焼時に流す空気流量を０．４リットル/ 分とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the air flow rate at the time of roasting was 0.4 liter / minute, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
還元条件を３００℃で３時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the reducing condition was changed to 300 ° C. for 3 hours, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
還元条件を５００℃で０．５時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the reducing condition was changed to 500 ° C. for 0.5 hour, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
還元時に流す水素ガス流量を０．０１リットル／分として同量の窒素ガスと混合して流し、還元時間を３時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the flow rate of hydrogen gas flowing at the time of reduction was 0.01 liters / minute and the mixture was mixed with the same amount of nitrogen gas and the reduction time was 3 hours. The particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
還元時に流す水素ガス流量を０．２リットル／分とし、同量の窒素ガスと混合して流した以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本実施例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the flow rate of hydrogen gas flowing at the time of reduction was 0.2 liter / min, and the mixture was flowed with the same amount of nitrogen gas, and this was passed through a # 100 sieve. Later, the particle size was measured.
Table 1 also shows the Mg content in the nickel hydroxide, roasting conditions and reducing conditions, heat loss ratio, and particle size measurement results in this example.
１００ｋｇの塩化ニッケル６水和物（住友金属鉱山製）と塩化マグネシウム６水和物（試薬一級、和光純薬製）２００ｇ（水酸化ニッケル中Ｍｇ含有量０．０６質量％相当）を純水２５０Ｌに溶解し塩化ニッケル水溶液を調製した。水酸化ナトリウム（試薬１級、和光純薬製）３５．５ｋｇを純水２５０Ｌに溶解した溶液を塩化ニッケル水溶液に添加し、生成した水酸化物をろ過し、さらにこれを１００Ｌの純水でろ過水洗した。その後、同様にろ過水洗を４回繰り返した後に、箱型大気乾燥機（ＴＤ−Ｂ−１０ＨＨ、温度設備研究所製）で１５０℃、４８時間の乾燥を行い、水酸化ニッケルを得た。得られた水酸化ニッケルを解砕した後、乾燥水酸化ニッケル粉１ｇあたり空気流量を０．０２リットル／分を流した連続式プッシャーキルンを用いて４７０℃で２時間焙焼して酸化ニッケル粉を得た。得られた酸化ニッケル粉について熱分析装置により熱減量比を求めた。さらに、酸化ニッケル粉を、酸化ニッケル粉１ｇあたり０．０５リットル／分の水素ガスと０．０２リットル／分の窒素ガスを混合して流した連続式プッシャーキルンを用いて４５０℃で１時間の還元を行い、ニッケル粉を得た。
得られたニッケル粉を＃１００の篩にかけ、そのニッケル粉の粒径を走査型電子顕微鏡（以下、ＳＥＭ）により測定した。水酸化ニッケル中のＭｇ添加量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例１］
100 kg of nickel chloride hexahydrate (manufactured by Sumitomo Metal Mining) and magnesium chloride hexahydrate (reagent grade, manufactured by Wako Pure Chemical Industries) 200 g (equivalent to Mg content of 0.06% by mass in nickel hydroxide) 250 L of pure water A nickel chloride aqueous solution was prepared. A solution prepared by dissolving 35.5 kg of sodium hydroxide (reagent 1 grade, manufactured by Wako Pure Chemical Industries, Ltd.) in 250 L of pure water is added to an aqueous nickel chloride solution, the formed hydroxide is filtered, and this is filtered through 100 L of pure water. Washed with water. Thereafter, after washing with filtered water four times in the same manner, drying was performed at 150 ° C. for 48 hours with a box-type atmospheric dryer (TD-B-10HH, manufactured by Temperature Equipment Laboratory) to obtain nickel hydroxide. After the obtained nickel hydroxide was crushed, the nickel oxide powder was roasted at 470 ° C. for 2 hours using a continuous pusher kiln in which an air flow rate of 0.02 liter / min per 1 g of the dried nickel hydroxide powder was flowed. Got. The heat loss ratio of the obtained nickel oxide powder was determined by a thermal analyzer. Further, the nickel oxide powder was mixed at 450 ° C. for 1 hour using a continuous pusher kiln in which hydrogen gas of 0.05 liter / min and nitrogen gas of 0.02 liter / min were mixed and flowed per gram of nickel oxide powder. Reduction was performed to obtain nickel powder.
The obtained nickel powder was passed through a # 100 sieve, and the particle size of the nickel powder was measured with a scanning electron microscope (hereinafter, SEM). Table 1 also shows the Mg addition amount in nickel hydroxide, roasting conditions and reduction conditions, heat loss ratio, and particle size measurement results.
[Comparative Example 1]
塩化ニッケル水溶液を塩化ニッケル６水和のみで調整した以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例２］
Nickel powder was obtained in the same manner as in Example 1 except that the nickel chloride aqueous solution was adjusted only with nickel chloride hexahydrate, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
[Comparative Example 2]
焙焼時に流す空気流量を０．０１リットル／分とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例３］
Nickel powder was obtained in the same manner as in Example 1 except that the air flow rate at the time of roasting was changed to 0.01 l / min, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
[Comparative Example 3]
焙焼条件を１７０℃で４８時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例４］
Nickel powder was obtained in the same manner as in Example 1 except that roasting conditions were changed to 170 ° C. for 48 hours, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
[Comparative Example 4]
焙焼条件を６００℃で２時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例５］
Nickel powder was obtained in the same manner as in Example 1 except that roasting conditions were set at 600 ° C. for 2 hours, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
[Comparative Example 5]
還元時に流す水素ガス流量を０．００５リットル／分として同量の窒素ガスと混合して流した以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例６］
Nickel powder was obtained in the same manner as in Example 1 except that the flow rate of hydrogen gas flowing at the time of reduction was 0.005 liters / minute and mixed with the same amount of nitrogen gas, and this was passed through a # 100 sieve. The particle size was measured.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
[Comparative Example 6]
還元条件を２５０℃で３時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
［比較例７］
Nickel powder was obtained in the same manner as in Example 1 except that the reducing condition was set at 250 ° C. for 3 hours, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
[Comparative Example 7]
還元条件を６００℃で０．５時間とした以外は、実施例１と同様にしてニッケル粉を得て、これを＃１００の篩にかけた後にその粒径を測定した。
本比較例における水酸化ニッケル中のＭｇ含有量、焙焼条件および還元条件、熱減量比、粒径測定結果を表１に併せて示す。
Nickel powder was obtained in the same manner as in Example 1 except that the reduction condition was 600 ° C. for 0.5 hour, and the particle size was measured after passing through a # 100 sieve.
Table 1 also shows the Mg content, roasting and reducing conditions, heat loss ratio, and particle size measurement results in nickel hydroxide in this comparative example.
以上の実施例から明らかなごとく、本発明に係る製造方法で得られた実施例のニッケル粉は、平均粒径（Ｄ５０）が０．２〜０．４μｍでシャープな粒度分布が得られた。これに対して、比較例１、２、７のニッケル粉では、平均粒径が０．４μｍより大きくなっているか、Ｄ９０が実施例よりも大きく粗大なニッケル粉が含まれていることがわかる。また、比較例３〜６のニッケル粉では、平均粒径が０．２〜０．４μｍとなっているもののＤ１０が細かいことから極微粒子が含まれ、さらにＤ９０が大きくなっていることから粗大粒子が含まれていることがわかる。したがって、比較例のニッケル粉は、極微粒子あるいは粗大粒子が含まれることからＭＬＣＣ内部電極用ニッケル粉として好ましくないことがわかる。 As is clear from the above examples, the nickel powder of the example obtained by the production method according to the present invention had an average particle size (D50) of 0.2 to 0.4 μm and a sharp particle size distribution. On the other hand, in the nickel powders of Comparative Examples 1, 2, and 7, it can be seen that the average particle diameter is larger than 0.4 μm, or that D90 is larger than that of the example and coarse nickel powder is included. In addition, in the nickel powders of Comparative Examples 3 to 6, although the average particle diameter is 0.2 to 0.4 μm, D10 is fine, so extremely fine particles are included, and D90 is large, and thus coarse particles. It can be seen that is included. Therefore, it can be seen that the nickel powder of the comparative example is not preferable as the nickel powder for MLCC internal electrodes because it contains extremely fine particles or coarse particles.
本発明は、水酸化ニッケルを加熱還元してニッケル粉を得る方法において、特定条件で水酸化ニッケルの焙焼を行なって酸化ニッケルを得ると共に、得られた酸化ニッケルを特定条件で加熱還元することにより、微細で均一な粒径のニッケル粉を大量に低コストで製造することができるという優れた効果を奏する。また、本発明法により得られる微細で均一な粒径のニッケル粉は、特に小型化、高容量化が進むＭＬＣＣ内部電極形成用として好適なものであり、その工業的価値は極めて大きい。 In the method of obtaining nickel powder by heating and reducing nickel hydroxide, the present invention obtains nickel oxide by baking nickel hydroxide under specific conditions, and heat-reducing the obtained nickel oxide under specific conditions. As a result, the nickel powder having a fine and uniform particle diameter can be produced in a large amount at a low cost. In addition, the fine and uniform nickel powder obtained by the method of the present invention is particularly suitable for forming MLCC internal electrodes whose size and capacity are increasing, and its industrial value is extremely large.
Claims (4)
記
０．５≦(室温〜４００℃の減量(質量％))／(室温〜８００℃の減量(質量％))≦１ The method for producing nickel powder according to claim 1, wherein the mass reduction of nickel oxide obtained by roasting satisfies the following condition when heated in a reducing atmosphere.
0.5 ≦ (weight loss from room temperature to 400 ° C. (mass%)) / (weight loss from room temperature to 800 ° C. (mass%)) ≦ 1
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007186221A JP4978785B2 (en) | 2007-07-17 | 2007-07-17 | Method for producing nickel powder |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007186221A JP4978785B2 (en) | 2007-07-17 | 2007-07-17 | Method for producing nickel powder |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2009024197A JP2009024197A (en) | 2009-02-05 |
| JP4978785B2 true JP4978785B2 (en) | 2012-07-18 |
Family
ID=40396296
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2007186221A Active JP4978785B2 (en) | 2007-07-17 | 2007-07-17 | Method for producing nickel powder |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4978785B2 (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5194876B2 (en) * | 2008-02-25 | 2013-05-08 | 住友金属鉱山株式会社 | Nickel oxide powder and method for producing the same |
| JP5170450B2 (en) * | 2009-02-25 | 2013-03-27 | 住友金属鉱山株式会社 | Method for producing nickel powder |
| JP5168592B2 (en) * | 2009-04-07 | 2013-03-21 | 住友金属鉱山株式会社 | Method for producing nickel powder |
| JP5141983B2 (en) * | 2009-04-17 | 2013-02-13 | 住友金属鉱山株式会社 | Nickel fine powder and method for producing the same |
| JP5182206B2 (en) * | 2009-04-24 | 2013-04-17 | 住友金属鉱山株式会社 | Nickel powder and method for producing the same |
| JP5369864B2 (en) * | 2009-04-24 | 2013-12-18 | 住友金属鉱山株式会社 | Nickel powder and method for producing the same |
| JP5310462B2 (en) * | 2009-10-13 | 2013-10-09 | 住友金属鉱山株式会社 | Nickel powder and method for producing the same |
| JP5663895B2 (en) * | 2010-02-19 | 2015-02-04 | 住友金属鉱山株式会社 | Nickel powder and method for producing the same |
| JP5979041B2 (en) * | 2013-03-13 | 2016-08-24 | 住友金属鉱山株式会社 | Method for producing nickel powder |
| JP6131773B2 (en) * | 2013-08-22 | 2017-05-24 | 住友金属鉱山株式会社 | Nickel powder, method for producing the same, and nickel paste using the same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000212609A (en) * | 1999-01-22 | 2000-08-02 | Sumitomo Metal Mining Co Ltd | Nickel powder for internal electrode of laminated ceramic capacitor and its production |
| JP4385457B2 (en) * | 1999-11-19 | 2009-12-16 | 堺化学工業株式会社 | Method for producing fine spherical metal nickel fine powder |
| JP4070585B2 (en) * | 2001-11-22 | 2008-04-02 | 日立マクセル株式会社 | Lithium-containing composite oxide and non-aqueous secondary battery using the same |
| JP2004315273A (en) * | 2003-04-15 | 2004-11-11 | Sumitomo Metal Mining Co Ltd | Nickel oxide powder with high specific surface area and excellent sintering property and its manufacturing method |
-
2007
- 2007-07-17 JP JP2007186221A patent/JP4978785B2/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| JP2009024197A (en) | 2009-02-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4978785B2 (en) | Method for producing nickel powder | |
| KR101236245B1 (en) | Metal powder for electrically conductive paste and electrically conductive paste | |
| JP5574154B2 (en) | Nickel powder and method for producing the same | |
| JP4063151B2 (en) | Porous spherical nickel powder and method for producing the same | |
| JP6135935B2 (en) | Method for producing wet nickel powder | |
| CN110028317B (en) | Nano barium titanate powder and preparation method thereof, ceramic dielectric layer and manufacturing method thereof | |
| JP5663895B2 (en) | Nickel powder and method for producing the same | |
| JP2007051050A (en) | Process of preparing low-temperature sintered microwave dielectric ceramic and low-temperature sintered microwave dielectric ceramic obtained by the same | |
| JP2013053030A (en) | Plate-like ruthenium oxide powder, method for producing the same, and thick film resistor composition using the same | |
| JP5310462B2 (en) | Nickel powder and method for producing the same | |
| JP4766910B2 (en) | Method for producing barium titanate powder, barium titanate powder, and barium titanate sintered body | |
| JP5170450B2 (en) | Method for producing nickel powder | |
| JP5046044B2 (en) | Method for producing magnesium oxide nanoparticles and method for producing magnesium oxide nanoparticles | |
| JP3812359B2 (en) | Method for producing metal powder | |
| EP3187289B1 (en) | Method for producing platinum-based alloy powder | |
| JP4150802B2 (en) | Metal powder processing method | |
| JP3474170B2 (en) | Nickel powder and conductive paste | |
| JP5979041B2 (en) | Method for producing nickel powder | |
| JP4643443B2 (en) | Method for producing barium titanate powder | |
| JP2008261054A (en) | Heat treating method for metal powder | |
| JP4540364B2 (en) | Nickel powder, and conductive paste and multilayer ceramic capacitor using the same | |
| JP4831518B2 (en) | Method for producing nickel powder | |
| WO2018105689A1 (en) | Zinc oxide varistor and method for manufacturing same | |
| JP2007169122A (en) | Barium titanate powder, its production method, and barium titanate sintered compact | |
| JP2004043883A (en) | Heat treatment method for metal powder |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20091124 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20110329 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20110510 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20120322 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20120404 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20150427 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 4978785 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |