JP2003221233A - Iron oxide powder for chip inductor and method for producing ferrite powder - Google Patents
Iron oxide powder for chip inductor and method for producing ferrite powderInfo
- Publication number
- JP2003221233A JP2003221233A JP2002023982A JP2002023982A JP2003221233A JP 2003221233 A JP2003221233 A JP 2003221233A JP 2002023982 A JP2002023982 A JP 2002023982A JP 2002023982 A JP2002023982 A JP 2002023982A JP 2003221233 A JP2003221233 A JP 2003221233A
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- iron oxide
- oxide powder
- particles
- particle size
- powder
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、チップインダクタ
用酸化鉄粉末およびフェライト粉末の製造方法に関す
る。TECHNICAL FIELD The present invention relates to a method for producing iron oxide powder and ferrite powder for a chip inductor.
【０００２】[0002]
【従来の技術】携帯電話をはじめとする携帯電子機器の
普及に伴い、チップインダクタ等のチップ部品が多用さ
れている。電子機器のさらなる高機能化、小型軽量化に
対応したチップ部品についても一層の小型化が進んでい
る。積層チップインダクタは、印刷法やドクターブレー
ド法を用いて成形したフェライト層と、印刷法で成形さ
れた内部電極を積層、焼結して製造され、導体電極間の
電気的導通は、スルーホールを用いて接続する方法など
により行われている。このような積層チップインダクタ
は、例えば特開平４−１８０６１０号公報に開示されて
いる。このような積層型のチップインダクタは小型化に
有利であるとともに、外鉄構造をとる為に、漏洩磁束が
小さく高密度実装にも適している。2. Description of the Related Art With the spread of portable electronic devices such as mobile phones, chip components such as chip inductors are widely used. The miniaturization of chip parts, which are compatible with higher functionality and smaller size and lighter weight of electronic devices, is also progressing. Multilayer chip inductors are manufactured by stacking and sintering a ferrite layer molded using the printing method and the doctor blade method, and an internal electrode molded using the printing method. It is performed by the method of connecting using. Such a multilayer chip inductor is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-180610. Such a laminated type chip inductor is advantageous for miniaturization, and since it has an outer iron structure, it has a small leakage magnetic flux and is suitable for high-density mounting.
【０００３】チップインダクタを構成するフェライト原
料は、酸化鉄、酸化ニッケル、酸化亜鉛、酸化銅等を混
合、仮焼、粉砕して得られる。フェライトの組成上、こ
れらの原料のうち、最も多くの量を必要とするのが酸化
鉄であり、フェライト粒子のサイズや均一性に及ぼす影
響も大きい。フェライトの原料となる酸化鉄には、噴霧
焙焼法等で製造された一次粒子の平均粒径が０．５〜１
μｍ程度の酸化鉄が多く用いられている。しかし、近年
のチップ部品の小型化に対応するため、より粒径が小さ
く、低温で仮焼できる酸化鉄が求められている。粒径の
小さな酸化鉄を用いてフェライトを作製する場合、より
低温で仮焼することが可能で、仮焼後も小さな粒径を維
持できる利点がある。そして次の粉砕工程で、容易に凝
集を崩して小粒径化させることができるため、小型磁気
素子用として好ましいフェライト粒子が得られる。The ferrite raw material forming the chip inductor is obtained by mixing, calcining and crushing iron oxide, nickel oxide, zinc oxide, copper oxide and the like. From the viewpoint of the composition of ferrite, iron oxide requires the largest amount of these raw materials, and has a great influence on the size and uniformity of ferrite particles. Iron oxide, which is a raw material of ferrite, has an average particle size of 0.5 to 1 of primary particles produced by a spray roasting method or the like.
Iron oxide of about μm is often used. However, in order to cope with the recent miniaturization of chip parts, there is a demand for iron oxide having a smaller particle size and capable of being calcined at a low temperature. When ferrite is produced using iron oxide having a small particle size, it has the advantage that it can be calcined at a lower temperature and that the small particle size can be maintained after calcination. Then, in the subsequent pulverization step, aggregation can be easily broken down to reduce the particle size, so that ferrite particles suitable for a small magnetic element can be obtained.
【０００４】しかし、噴霧焙焼法などの乾式法により製
造される酸化鉄では、一次粒子の粒径をより小さくする
ことが困難である。従来の噴霧焙焼法で製造した一次粒
子の平均粒径が０．５〜１μｍ程度の酸化鉄を用いてフ
ェライトを作製する場合、仮焼温度を高くする必要があ
り、そのため仮焼工程で粒成長が促進され、粉砕時間を
長くする必要がある。この結果、粉砕機器からの不純物
が増加する問題もあり、磁気素子の小型化には適さな
い。一方、湿式法を用いると、一次粒子の粒径が小さい
酸化鉄を得やすい利点がある。しかし、湿式法では溶液
中で鉄酸化物を生成させるため、乾燥工程を必要とす
る。酸化鉄は粒径が小さくなるほど、乾燥時に粒子同士
が強固に固まって凝集粒子を形成する傾向がある。この
ため、乾燥工程の存在は、粒径が１〜１００μｍの粗大
な凝集粒子が生成し、その後の解砕工程を経ても凝集粒
子が残る問題がある。酸化鉄中に粒径の大きな凝集粒子
を多く含む場合、仮焼温度を充分下げることができない
ため粒成長が促進され、粉砕時間を長くする必要が生じ
る。However, with iron oxide produced by a dry method such as a spray roasting method, it is difficult to reduce the particle size of the primary particles. When producing ferrite using iron oxide having an average particle size of primary particles produced by a conventional spray roasting method of about 0.5 to 1 μm, it is necessary to raise the calcination temperature, and therefore the calcination step is performed. Growth is promoted and grinding time needs to be extended. As a result, there is a problem that impurities from the crushing device increase, which is not suitable for downsizing the magnetic element. On the other hand, when the wet method is used, there is an advantage that iron oxide having a small primary particle size can be easily obtained. However, the wet method requires a drying step because iron oxide is generated in the solution. As the particle size of iron oxide becomes smaller, the particles are more likely to solidify to form agglomerated particles during drying. Therefore, the presence of the drying step causes a problem that coarse agglomerated particles having a particle size of 1 to 100 μm are generated, and the agglomerated particles remain even after the subsequent crushing step. When the iron oxide contains a large amount of agglomerated particles having a large particle size, the calcination temperature cannot be lowered sufficiently, grain growth is promoted, and it becomes necessary to lengthen the grinding time.
【０００５】平均粒径が０．５〜１２μｍで、二次粒子
を伴わず、インダクタやトランスに好適な酸化鉄は、例
えば特開昭５９−２１５２７号公報に開示されている。
しかし、同公報に開示された酸化鉄は、比表面積が２．
３１〜３．５ｍ2 ／ｇと小さく、酸化鉄の平均粒径が
０．５〜１２μｍと大きいため、仮焼温度を充分に下げ
ることができない。また、凝集粒子の粒径が、一次粒子
の１０倍以下で、インダクタ等の磁心や素体材として使
用される酸化鉄粉末を含む酸化物磁性材料は、特開平９
−１７６２５号公報に開示されている。しかし、同公報
に開示の酸化鉄では、粒径の大きい凝集粒子の存在割合
が不明である。Iron oxide having an average particle size of 0.5 to 12 μm and suitable for inductors and transformers without secondary particles is disclosed in, for example, Japanese Patent Application Laid-Open No. 59-21527.
However, the iron oxide disclosed in the publication has a specific surface area of 2.
It is as small as 31 to 3.5 m 2 / g and the average particle size of iron oxide is as large as 0.5 to 12 μm, so the calcination temperature cannot be lowered sufficiently. Further, an oxide magnetic material containing iron oxide powder, in which the particle size of agglomerated particles is 10 times or less of that of primary particles and which is used as a magnetic core such as an inductor or an element material, is disclosed in Japanese Patent Application Laid-Open No. H9-90187.
No. 17625. However, in the iron oxide disclosed in the publication, the existence ratio of agglomerated particles having a large particle size is unknown.
【０００６】個数平均径が０．０５〜１．０μｍの酸化
鉄粒状粒子が凝集している粒子径２０μｍ以下の凝集粒
子からなる着色顔料用の酸化鉄粉末が、特開平８−２５
９２３８号公報に開示されている。しかし、同公報に開
示の酸化物粉末の用途は着色顔料であり、チップインダ
クタを含む磁気電子部品への適用は示されていない。個
数平均粒子径が０．０５〜１μｍの酸化鉄一次粒子が凝
集してなる個数平均粒子径が３０〜３０００μｍの粒状
酸化鉄凝集粒子が、特開２０００−３５１６３１号公報
に開示されている。しかし、同公報では、粒径３０μｍ
以上の凝集粒子の重量比率が８０重量％以上であるよう
に、凝集体は粒径が大きいことが好まれ、また、用途と
して、静電複写磁性トナー用材料紛、静電潜像現像用キ
ャリア用材料紛、塗料用黒色顔料紛が挙げられている。[0006] An iron oxide powder for a color pigment comprising agglomerated particles of iron oxide granular particles having a number average particle diameter of 0.05 to 1.0 µm and having a particle diameter of 20 µm or less is disclosed in JP-A-8-25.
It is disclosed in Japanese Patent No. 9238. However, the use of the oxide powder disclosed in the publication is a color pigment, and its application to a magnetic electronic component including a chip inductor is not shown. Japanese Patent Application Laid-Open No. 2000-351631 discloses granular iron oxide agglomerated particles having a number average particle diameter of 30 to 3000 μm formed by agglomeration of iron oxide primary particles having a number average particle diameter of 0.05 to 1 μm. However, in this publication, the particle size is 30 μm.
It is preferred that the agglomerates have a large particle size such that the weight ratio of the above agglomerated particles is 80% by weight or more. Further, as applications, electrostatic copying magnetic toner material powders and electrostatic latent image developing carriers are used. Material powders and black pigment powders for paints are mentioned.
【０００７】したがって、一次粒子の平均粒径が小さ
く、かつ凝集体の粒径が小さいことにより、低温仮焼が
可能なチップインダクタの製造に適した酸化鉄粉末は従
来存在しなかった。Therefore, no iron oxide powder suitable for manufacturing a chip inductor capable of low temperature calcination has hitherto been available due to the small average particle size of primary particles and the small particle size of aggregates.
【０００８】[0008]
【発明が解決しようとする課題】本発明は、上記の問題
を解決するため、粒径が小さく、低温仮焼が可能で、粉
砕性に優れたフェライトを得ることができるチップイン
ダクタ用酸化鉄粉末を提供することを課題とする。ま
た、本発明は、製造時の仮焼温度が低く、かつ製造され
るフェライト粒子の比表面積が大きいフェライト粒子の
製造方法を提供することを課題とする。In order to solve the above problems, the present invention provides an iron oxide powder for a chip inductor, which has a small particle size, can be calcined at a low temperature, and can obtain a ferrite having excellent pulverizability. The challenge is to provide. Another object of the present invention is to provide a method for producing ferrite particles having a low calcination temperature during production and a large specific surface area of the produced ferrite particles.
【０００９】[0009]
【課題を解決するための手段】フェライトを作製する場
合の仮焼温度や粉砕性に影響する因子として、一次粒子
径が広く知られている。しかし、本発明者らは、仮焼時
間や粉砕性は単に一次粒子径だけでなく、凝集粒子（二
次粒子）の大きさ、およびその量にも依存していること
を見出して本発明に至った。すなわち、上記の課題は、
以下に示す本発明により達成される。本発明は、平均粒
径０．０２〜０．２μｍのＦｅ2 Ｏ3 一次粒子と、その
凝集粒子からなる酸化鉄粉末であって、粒径４５μｍ以
上の凝集粒子の含有量が前記酸化鉄粉末中２０質量％以
下であることを特徴とするチップインダクタ用酸化鉄粉
末を提供する。また、本発明は、平均粒径０．０２〜
０．２μｍのＦｅ2 Ｏ3 一次粒子と、その凝集粒子から
なる酸化鉄粉末であって、粒径４５μｍ以上の凝集粒子
の含有量が、前記酸化鉄粉末中２０質量％以下である前
記酸化鉄粉末に、必要な他の金属化合物を混合して、仮
焼することにより、スピネル化率が９０％以上となる最
低温度が７４０℃以下で、仮焼後比表面積が３．５ｍ2
／ｇ以上であるフェライト粉末を製造する方法を提供す
る。The primary particle diameter is widely known as a factor that affects the calcination temperature and pulverizability when producing ferrite. However, the present inventors have found that the calcination time and the pulverizability depend not only on the primary particle size but also on the size of the agglomerated particles (secondary particles) and the amount thereof, and the present invention I arrived. That is, the above problem is
It is achieved by the present invention described below. The present invention is an iron oxide powder composed of Fe 2 O 3 primary particles having an average particle size of 0.02 to 0.2 μm and aggregated particles thereof, wherein the content of the aggregated particles having a particle size of 45 μm or more is the iron oxide powder. Provided is an iron oxide powder for a chip inductor, characterized in that the content is 20% by mass or less. The present invention also has an average particle size of 0.02 to 0.02.
Iron oxide powder consisting of 0.2 μm Fe 2 O 3 primary particles and aggregated particles thereof, wherein the content of the aggregated particles having a particle size of 45 μm or more is 20 mass% or less in the iron oxide powder. By mixing the powder with other necessary metal compounds and calcining, the minimum temperature at which the spinelization rate is 90% or more is 740 ° C. or less, and the specific surface area after calcining is 3.5 m 2.
Provided is a method for producing a ferrite powder having a density of at least 1 g / g.
【００１０】[0010]
【発明の実施の形態】以下に、本発明を詳細に説明す
る。一般に一次粒子径が小さい酸化鉄を用いると低温で
仮焼ができ、仮焼工程での粒成長を抑制することができ
るため、粉砕性に優れたフェライト粒子が得られる。し
かし、単に一次粒子径を小さくするだけでは仮焼温度を
充分に低下できない。仮焼温度は酸化鉄の比表面積の他
に、凝集粒子（二次粒子）の粒径や量にも依存するから
である。BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below. Generally, when iron oxide having a small primary particle diameter is used, calcination can be performed at a low temperature and grain growth in the calcination step can be suppressed, so that ferrite particles having excellent grindability can be obtained. However, the calcination temperature cannot be lowered sufficiently by simply reducing the primary particle size. This is because the calcination temperature depends not only on the specific surface area of iron oxide but also on the particle size and amount of aggregated particles (secondary particles).
【００１１】本発明の酸化鉄粉末は、平均粒径は０．０
２〜０．２μｍのＦｅ2 Ｏ3 一次粒子とその凝集粒子か
らなることを特徴とする。本発明の酸化鉄粉末におい
て、一次粒子の平均粒径は、０．０３〜０．１５μｍで
あることがより好ましく、さらに好ましくは０．０４〜
０．１μｍである。一次粒子の平均粒径が０．０２〜
０．２μｍの酸化鉄を用いると、例えば噴霧焙焼法で製
造された一次粒子の平均粒径がより大きな酸化鉄に比べ
てより低温で仮焼し、短時間で所定の粒径まで粉砕する
ことができ、チップインダクタ用フェライト粉末として
適したものとなる。一次粒子の平均粒径が０．２μｍ超
の酸化鉄では、仮焼温度を充分下げることができず、そ
のため仮焼工程で粒成長が進み、粉砕時間を長くする必
要があり、粉砕機器からの不純物の混入も増加するた
め、チップインダクタ用として適さない。一方、一次粒
子の平均粒径が０．０２μｍ未満の酸化鉄では、仮焼温
度は低下できるものの、反応性が高くなるため、粉砕時
間が長くなり、その結果、粉砕機器からの不純物の混入
が増加するため、チップインダクタ用として適さないも
のとなる。なお、一次粒子の平均粒径の測定は、例えば
走査型電子顕微鏡（ＳＥＭ）、投透過型電子顕微鏡によ
る顕微鏡写真上の粒径を計測し、個数平均することで求
めることができる。The iron oxide powder of the present invention has an average particle size of 0.0
It is characterized by comprising Fe 2 O 3 primary particles of 2 to 0.2 μm and aggregated particles thereof. In the iron oxide powder of the present invention, the average particle diameter of the primary particles is more preferably 0.03 to 0.15 μm, further preferably 0.04 to
It is 0.1 μm. The average particle size of the primary particles is 0.02
When 0.2 μm of iron oxide is used, it is calcined at a lower temperature than iron oxide having a larger average particle size of primary particles produced by, for example, a spray roasting method, and is ground to a predetermined particle size in a short time. Therefore, it becomes suitable as a ferrite powder for a chip inductor. With iron oxide having an average primary particle diameter of more than 0.2 μm, the calcination temperature cannot be lowered sufficiently, and therefore grain growth proceeds in the calcination step, and it is necessary to lengthen the crushing time. It is not suitable for a chip inductor because it also contains impurities. On the other hand, with iron oxide having an average primary particle size of less than 0.02 μm, the calcination temperature can be lowered, but the reactivity becomes high, so that the pulverization time becomes long and, as a result, impurities from the pulverization equipment are mixed. Since it increases, it becomes unsuitable for chip inductors. The average particle size of the primary particles can be determined by, for example, measuring the particle size on a micrograph with a scanning electron microscope (SEM) or a transmission electron microscope and averaging the numbers.
【００１２】本発明の酸化鉄粉末は、粒径４５μｍ以上
の凝集粒子（二次粒子）の含有量が酸化鉄粉末中２０質
量％以下であることを特徴とする。粒径４５μｍ以上の
凝集粒子の比率の測定方法としては、例えば、１００ｇ
の粉体を３００ｍｌの純水と混合し、所定の時間、振盪
させてスラリー化した後、目開き４５μｍの篩を用いて
湿式分級し、篩上に残った粉体を回収して乾燥し、重量
を測定する方法が挙げられる。粒径４５μｍ以上の凝集
粒子（二次粒子）の含有量が酸化鉄中２０質量％を超え
ると仮焼温度を高くする必要が生じ、粉砕時間を長くす
ることが必要となる。この結果、粉砕機器からの不純物
の混入も増加するため、チップインダクタ用として適さ
ないフェライト粒子となる。また均一混合が難しくなる
ため、フェライトとしての均一性も悪くなる。粒径４５
μｍ以上の凝集粒子（二次粒子）の含有量は、好ましく
は酸化鉄粉末中１０質量％以下であり、さらに好ましく
は５質量％以下であり、１質量％以下であることが特に
好ましい。粒径４５μｍ以上の凝集粒子の含有量が、酸
化鉄粉末中２０質量％超であると仮焼時にフェライト成
分であるＮｉ，Ｃｕ，Ｚｎなどが酸化鉄中に拡散し難い
ため、仮焼温度を上げる必要がある。このため、粒成長
が生じ、仮焼後の粉砕時間が長くなる。その結果、チッ
プインダクタ用としては適さないフェライト粒子とな
る。The iron oxide powder of the present invention is characterized in that the content of aggregated particles (secondary particles) having a particle diameter of 45 μm or more is 20% by mass or less in the iron oxide powder. As a method for measuring the ratio of aggregated particles having a particle size of 45 μm or more, for example, 100 g
Powder was mixed with 300 ml of pure water, shaken for a predetermined time to form a slurry, and then wet classified using a sieve having an opening of 45 μm, and the powder remaining on the sieve was collected and dried, A method of measuring the weight may be mentioned. If the content of aggregated particles (secondary particles) having a particle size of 45 μm or more exceeds 20% by mass in iron oxide, it is necessary to raise the calcination temperature and prolong the pulverization time. As a result, the amount of impurities mixed from the crushing device also increases, and the ferrite particles are unsuitable for chip inductors. Moreover, since uniform mixing becomes difficult, the uniformity as ferrite also deteriorates. Particle size 45
The content of agglomerated particles (secondary particles) having a size of μm or more is preferably 10% by mass or less in the iron oxide powder, more preferably 5% by mass or less, and particularly preferably 1% by mass or less. If the content of the agglomerated particles having a particle size of 45 μm or more is more than 20% by mass in the iron oxide powder, ferrite components such as Ni, Cu, and Zn are less likely to diffuse into the iron oxide. Need to raise. For this reason, grain growth occurs and the crushing time after calcination becomes long. As a result, the ferrite particles are not suitable for chip inductors.
【００１３】本発明の酸化鉄は、ＢＥＴ法で測定した比
表面積が、６〜６０ｍ2 ／ｇであることが好ましい。よ
り好ましくは、比表面積が、８〜４０ｍ2 である。酸化
鉄の比表面積が上記の範囲であれば、仮焼温度を充分下
げることができ、凝集粒子の粉砕時間が短くて済むこと
から、粉砕機器からの異物の混入が少なく、チップイン
ダクタ用として好ましい。The iron oxide of the present invention preferably has a specific surface area measured by the BET method of 6 to 60 m 2 / g. More preferably, the specific surface area is 8 to 40 m 2 . If the specific surface area of the iron oxide is in the above range, the calcination temperature can be sufficiently lowered, and the crushing time of the agglomerated particles can be shortened, so that the inclusion of foreign matter from the crushing device is small and it is preferable for the chip inductor. .
【００１４】本発明の酸化鉄において、酸化鉄粉末の形
態は、α−Ｆｅ2 Ｏ3 単相、γ−Ｆｅ2 Ｏ3 単相、また
はα−Ｆｅ2 Ｏ3 相およびγ−Ｆｅ2 Ｏ3 相の混合相の
いずれであってもよい。酸化鉄粉末の形態は、Ｘ線回折
法により測定することができる。従来の噴霧焙焼法で製
造されるフェライト用原料酸化鉄は、α−Ｆｅ2 Ｏ3 単
相である。本発明の酸化鉄粉末の形態がα−Ｆｅ2 Ｏ3
単相である場合、従来のフェライト用酸化鉄粉末と同様
の特性を有しており、かつ一次粒子の平均粒径が小さい
ことから、チップインダクタ用原料として、好適な性
能、すなわち低温仮焼性と優れた粉砕性を示す。一方、
従来の噴霧焙焼法ではγ−Ｆｅ2 Ｏ3 相の酸化鉄粉末を
製造することができないため、フェライト用原料として
用いられていなかった。本発明者らは、湿式法を用いて
γ−Ｆｅ2 Ｏ3 単相の酸化鉄粉末を製造し、その特性を
調べることにより、チップインダクタ用原料としてα−
Ｆｅ2Ｏ3 単相よりも優れた性能を示すことを確認して
いる。In the iron oxide of the present invention, the form of the iron oxide powder is α-Fe 2 O 3 single phase, γ-Fe 2 O 3 single phase, or α-Fe 2 O 3 phase and γ-Fe 2 O 3 phase. It may be any of mixed phases. The form of the iron oxide powder can be measured by an X-ray diffraction method. The raw material iron oxide for ferrite produced by the conventional spray roasting method is an α-Fe 2 O 3 single phase. The form of the iron oxide powder of the present invention is α-Fe 2 O 3
When it is a single phase, it has the same characteristics as the conventional iron oxide powder for ferrite, and the average particle size of the primary particles is small, so it is suitable as a raw material for chip inductors, that is, low temperature calcination property. And shows excellent pulverizability. on the other hand,
Since the conventional spray roasting method cannot produce a γ-Fe 2 O 3 phase iron oxide powder, it has not been used as a raw material for ferrite. The present inventors produced a γ-Fe 2 O 3 single-phase iron oxide powder by using a wet method, and examined its characteristics to obtain α- as a raw material for a chip inductor.
It has been confirmed that it exhibits superior performance to the Fe 2 O 3 single phase.
【００１５】γ−Ｆｅ2 Ｏ3 単相の酸化鉄粉末は、湿式
法でマグネタイト（Ｆｅ3 Ｏ4 ）を合成し、これを加熱
酸化することにより、Ｆｅ2 Ｏ3 を製造する方法におい
て、Ｆｅ3 Ｏ4 の加熱酸化温度を調節することで得るこ
とができる。具体的には、加熱酸化温度を１８０〜２５
０℃とすることにより、γ−Ｆｅ2Ｏ3 単相の酸化鉄粉
末が得られる。一方、加熱酸化温度が４２０℃以上の場
合、α−Ｆｅ2 Ｏ3 単相の酸化鉄粉末が得られる。γ−
Ｆｅ2 Ｏ3 単相の酸化鉄粉末は、α−Ｆｅ2 Ｏ3 相の酸
化鉄粉末よりも加熱酸化温度が低いため、比表面積の低
下や凝集粒の生成が少なく、チップインダクタ用原料と
して好適な粉体特性を容易に得ることができる。The γ-Fe 2 O 3 single-phase iron oxide powder is obtained by synthesizing magnetite (Fe 3 O 4 ) by a wet method and heating and oxidizing it to produce Fe 2 O 3. It can be obtained by adjusting the heating and oxidation temperature of 3 O 4 . Specifically, the heating oxidation temperature is 180 to 25
By setting the temperature to 0 ° C., γ-Fe 2 O 3 single-phase iron oxide powder can be obtained. On the other hand, when the heating oxidation temperature is 420 ° C. or higher, α-Fe 2 O 3 single-phase iron oxide powder is obtained. γ-
Fe 2 O 3 single-phase iron oxide powder has a lower heating and oxidation temperature than α-Fe 2 O 3 -phase iron oxide powder, so it has a smaller specific surface area and less aggregated particles, and is suitable as a raw material for chip inductors. It is possible to easily obtain various powder characteristics.
【００１６】また、加熱酸化温後が２３０〜４６０℃の
場合、α−Ｆｅ2 Ｏ3 相とγ−Ｆｅ 2 Ｏ3 相の混合相の
酸化鉄粉末が得られる。この場合も、加熱酸化温度が、
α−Ｆｅ2 Ｏ3 単相を製造する場合よりも低いため、チ
ップインダクタ用原料として優れた特性を有する。After the temperature of heating and oxidation is 230 to 460 ° C.
In case of α-Fe2O3Phase and γ-Fe 2O3Mixed phase
An iron oxide powder is obtained. Also in this case, the heating oxidation temperature is
α-Fe2O3Since it is lower than when producing a single phase,
It has excellent characteristics as a raw material for inductors.
【００１７】上記の特徴を有する本発明の酸化鉄粉末
は、湿式法を用いて製造されることが好ましい。湿式法
を用いて製造される酸化鉄粉末は、噴霧焙焼法などの乾
式法で製造される酸化鉄に比べ、粒径が小さく、かつ粒
径が揃っており、チップインダクタ用に適している。こ
こでいう湿式法とは共沈法、空気酸化法、水熱法など溶
液中で鉄酸化物を生成させる反応のことを指している。
また本発明の酸化鉄粉末には水溶液中で直接生成される
ものの他に、湿式法で合成されたマグネタイト（Ｆｅ3
Ｏ4 ）やゲータイト（α−ＦｅＯＯＨ）などの鉄酸化物
を加熱することにより製造されるものも含まれる。The iron oxide powder of the present invention having the above characteristics is preferably manufactured by a wet method. Iron oxide powder manufactured using a wet method has a smaller particle size and a uniform particle size than iron oxide manufactured by a dry method such as spray roasting, and is suitable for chip inductors. . The wet method as used herein refers to a reaction such as a coprecipitation method, an air oxidation method, or a hydrothermal method that produces iron oxide in a solution.
In addition to the iron oxide powder of the present invention which is produced directly in an aqueous solution, magnetite (Fe 3
Those produced by heating iron oxides such as O 4 ) and goethite (α-FeOOH) are also included.
【００１８】湿式法で合成された酸化鉄は、ろ過により
溶液を分離した後、乾燥、解砕される。湿式法で製造さ
れたマグネタイト（Ｆｅ3 Ｏ4 ）やゲータイト（α−Ｆ
ｅＯＯＨ）などの鉄酸化物を経由する場合、加熱工程を
経てＦｅ2 Ｏ3 が得られる。これらの工程のうち、乾燥
工程で乾燥ケーキができる過程（水分が減少する過程）
で凝集が生じる。この乾燥ケーキを解砕することによ
り、酸化鉄粉末（またはマグネタイト粉末やゲータイト
粉末）が得られる。マグネタイトやゲータイトなどの鉄
酸化物から加熱工程を経て酸化鉄を製造する方法では、
この加熱工程においても凝集が生じる。この凝集を解砕
（または粉砕）することにより酸化鉄粉末を得ることが
できる。Iron oxide synthesized by the wet method is dried and crushed after separating the solution by filtration. Wet-processed magnetite (Fe 3 O 4 ) and goethite (α-F)
When passing through an iron oxide such as eOOH), Fe 2 O 3 is obtained through a heating process. Of these processes, the process of forming a dry cake in the drying process (process of reducing water content)
Aggregation occurs at. By crushing this dried cake, iron oxide powder (or magnetite powder or goethite powder) is obtained. In the method of producing iron oxide through a heating step from iron oxide such as magnetite and goethite,
Aggregation also occurs in this heating step. Iron oxide powder can be obtained by crushing (or crushing) this aggregation.
【００１９】従来の噴霧焙焼法で製造された粒径の大き
な（一次粒子の平均粒径が０．５〜１μｍ）酸化鉄の場
合には、容易に粒子の凝集を解砕し、凝集が少ない酸化
鉄粉末を得ることができた。また、特開平８−２５９２
３８号公報に記載された湿式法で合成される顔料用の酸
化鉄粉末の場合、その用途が顔料であるため、酸化鉄粉
末の凝集は、特に問題とならなかった。しかし、本発明
の酸化鉄粉末のように、用途がチップインダクタである
場合、一次粒子の平均粒径が小さいことが求められる。
酸化鉄粉末の粒子が小さくなると、粒子同士の凝集が強
くなり、例えば、粒径が１〜３００μｍ程度の凝集体を
生ずる。このような凝集体は、従来の噴霧焙焼法で製造
される酸化鉄粉末に比べて解砕することが困難であり、
凝集体の存在が問題となる。しかも、このような凝集体
を解砕する際の困難さは、粒子の粒径が小さくなるほど
（比表面積が大きくなるほど）増加する。In the case of iron oxide having a large particle size (average particle size of primary particles is 0.5 to 1 μm) produced by the conventional spray roasting method, the agglomeration of the particles is easily crushed to cause agglomeration. A small amount of iron oxide powder could be obtained. In addition, JP-A-8-2592
In the case of the iron oxide powder for pigments synthesized by the wet method described in Japanese Patent Laid-Open No. 38, the use thereof is a pigment, so that the aggregation of the iron oxide powder does not cause any particular problem. However, when the application is a chip inductor like the iron oxide powder of the present invention, it is required that the average particle size of the primary particles is small.
When the particles of the iron oxide powder become small, the particles are strongly aggregated with each other, and, for example, aggregates having a particle diameter of about 1 to 300 μm are generated. Such agglomerates are more difficult to disintegrate than iron oxide powder produced by a conventional spray roasting method,
The presence of aggregates is a problem. Moreover, the difficulty in disintegrating such agglomerates increases as the particle size of the particles decreases (the specific surface area increases).
【００２０】このような問題に対し、本発明者らは、酸
化鉄粉末を解砕および／または分級することで、粒径４
５μｍ以上の凝集粒子の含有量が酸化鉄粉末中２０質量
％以下になるように粒度を調整することにより、フェラ
イト粒子の製造に使用した場合に、低温での仮焼が可能
で、粉砕性に優れたフェライト粒子が得られることを見
出した。本発明の酸化鉄粉末の製造において、粒度調整
に用いる解砕（または粉砕）方法としては、アトマイ
ザ、パルベライザ等の機械的な解砕（または粉砕）方
法、ジェットミルのような気流式の解砕（または粉砕）
方法、乾式ボールミルによる解砕（粉砕）方法のいずれ
であってもよい。解砕（または）粉砕方法は、製造され
る粒度調整後の酸化鉄粉末の粒子径等、酸化鉄粉末に要
求される条件に応じて適宜選択することができ、例え
ば、粒度調整後の粒子径が小さくなるほど、粉砕エネル
ギーの大きな方式が必要となる。一方、分級方法として
は、篩分級、または気流式の分級機などを使用すること
ができる。なお、解砕（または粉砕）および分級は、い
ずれか一方のみを実施したのでよく、または両方を実施
したのでもよい。粒度調整後の粒径が小さいことが求め
られる場合、解砕（または粉砕）と分級を組み合わせて
使用することが好ましい。To solve such a problem, the inventors of the present invention crushed and / or classified iron oxide powder to obtain a particle size of 4
By adjusting the particle size so that the content of agglomerated particles of 5 μm or more in iron oxide powder is 20% by mass or less, calcination at low temperature is possible when using for the production of ferrite particles, and pulverizability is improved. It was found that excellent ferrite particles can be obtained. In the production of the iron oxide powder of the present invention, as a crushing (or crushing) method used for particle size adjustment, a mechanical crushing (or crushing) method such as an atomizer or a palberizer, or a gas stream type crushing method such as a jet mill is used. (Or crush)
Any of a method and a crushing (crushing) method using a dry ball mill may be used. The crushing (or) pulverizing method can be appropriately selected according to the conditions required for the iron oxide powder, such as the particle size of the iron oxide powder after the particle size adjustment to be produced, for example, the particle size after the particle size adjustment. The smaller the value, the larger the grinding energy required. On the other hand, as a classification method, a sieve classification or an air flow type classifier can be used. It should be noted that the crushing (or crushing) and the classification may be performed by only one of them, or both may be performed. When the particle size after particle size adjustment is required to be small, it is preferable to use crushing (or crushing) and classification in combination.
【００２１】本発明のフェライト粒子の製造方法では、
本発明の酸化鉄粉末、すなわち、平均粒径０．０２〜
０．２μｍのＦｅ2 Ｏ3 一次粒子と、その凝集粒子から
なる酸化鉄粉末であって、粒径４５μｍ以上の凝集粒子
の含有量が、酸化鉄粉末中２０質量％以下である酸化鉄
粉末と、必要な他の金属化合物とをボールミル等を用い
て混合する。必要な他の金属化合物はフェライト粒子の
製造に使用される金属化合物であれば特に限定されな
い。このような金属化合物としては、例えばＮｉＯ、Ｃ
ｕＯ、ＺｎＯ、ＭｇＯなどの金属酸化物が例示される。In the method for producing ferrite particles of the present invention,
The iron oxide powder of the present invention, that is, an average particle size of 0.02
Fe 2 O 3 primary particles of 0.2 μm and iron oxide powder composed of agglomerated particles thereof, wherein the content of the agglomerated particles having a particle diameter of 45 μm or more is 20 mass% or less in the iron oxide powder, and , And other necessary metal compounds are mixed using a ball mill or the like. The other metal compound required is not particularly limited as long as it is a metal compound used for producing ferrite particles. Examples of such a metal compound include NiO and C
Examples are metal oxides such as uO, ZnO and MgO.
【００２２】本発明の方法において、酸化鉄粉末と、他
の金属化合物とは、混合物中における酸化鉄の含有量が
４０〜５０ｍｏｌ％になるような割合で混合する。酸化
鉄の含有量が５０ｍｏｌ％を超えると、Ｆｅ2+の存在に
より電気抵抗値が急激に低下する。電気抵抗の低下は、
高周波領域で使用するとき渦電流の発生でフェライトコ
アでの損失を急増させてしまう。また、４０ｍｏｌ％未
満になるとフェライトの透磁率低下に伴うインダクタン
スの劣化が大きい。好ましい酸化鉄の含有量は４７〜４
９．８ｍｏｌ％である。In the method of the present invention, the iron oxide powder and the other metal compound are mixed in a ratio such that the iron oxide content in the mixture is 40 to 50 mol%. When the content of iron oxide exceeds 50 mol%, the electric resistance value sharply decreases due to the presence of Fe 2+ . The decrease in electrical resistance is
When used in the high frequency range, the loss in the ferrite core increases rapidly due to the generation of eddy currents. On the other hand, if it is less than 40 mol%, the inductance is greatly deteriorated due to the decrease in the magnetic permeability of ferrite. The preferable iron oxide content is 47 to 4
It is 9.8 mol%.
【００２３】ＺｎＯの混合は、製造されるフェライト粒
子のインダクタンスとキュリー温度に大きな影響を与え
る。キュリー温度は磁気素子の耐熱性を決める重要なパ
ラメータである。ＺｎＯを混合する場合、混合物中にお
けるＺｎＯの含有量は５〜３５ｍｏｌ％であることが好
ましい。３５ｍｏｌ％を超えるとインダクタンスは高い
ものの、キュリー温度が低下する。より好ましいＺｎＯ
の含有量は１０〜３５ｍｏｌ％である。Mixing of ZnO has a great influence on the inductance and Curie temperature of the ferrite particles produced. The Curie temperature is an important parameter that determines the heat resistance of the magnetic element. When ZnO is mixed, the content of ZnO in the mixture is preferably 5 to 35 mol%. If it exceeds 35 mol%, the Curie temperature is lowered although the inductance is high. More preferred ZnO
Is 10 to 35 mol%.
【００２４】ＣｕＯの混合は、製造されるフェライト粒
子の焼成温度の低下に有効である。ＣｕＯを混合する場
合、混合物中におけるＣｕＯの含有量は０〜２０ｍｏｌ
％であることが好ましい。２０ｍｏｌ％を超えると、焼
成温度は低下するがインダクタンスが劣化する。より好
ましいＣｕＯの含有量は５〜１５ｍｏｌ％である。Mixing CuO is effective in lowering the firing temperature of the ferrite particles produced. When CuO is mixed, the content of CuO in the mixture is 0 to 20 mol.
% Is preferable. If it exceeds 20 mol%, the firing temperature is lowered but the inductance is deteriorated. A more preferable CuO content is 5 to 15 mol%.
【００２５】また、本発明の方法では、上記の金属化合
物以外に、フェライト粒子の製造に通常使用される他の
添加成分を混合してもよい。このような添加成分として
は、具体的には、例えば、Ｓｉ、Ｃａ、Ｎｂ、Ｔａ、
Ｖ、Ｔｉ、Ｓｎ、Ｎａ、Ｋ、Ｃｏ、Ｗ、Ｂｉ、Ｉｎ、Ｈ
ｂなどが例示される。このような添加成分の含有量は特
に限定されないが、０〜２５ｍｏｌ％程度であることが
好ましい。なお、金属化合物や添加成分は、最終的に酸
化物の形態になればよく、混合時には酸化物、水酸化
物、炭酸塩などの形態であってもよい。In the method of the present invention, in addition to the above-mentioned metal compound, other additive components usually used for producing ferrite particles may be mixed. As such an additive component, specifically, for example, Si, Ca, Nb, Ta,
V, Ti, Sn, Na, K, Co, W, Bi, In, H
b etc. are illustrated. The content of such an additive component is not particularly limited, but is preferably about 0 to 25 mol%. It should be noted that the metal compound and the additive component may be in the form of oxide in the end, and may be in the form of oxide, hydroxide, carbonate or the like when mixed.
【００２６】本発明の方法では、上記の混合物を仮焼し
てフェライト粒子とする。仮焼温度は７４０℃以下であ
り、７００℃以下であるのがより好ましい。７４０℃を
超えると、仮焼時に粒成長が進み、フェライト粒子の粉
砕性を悪化させる。仮焼を終えるタイミングはスピネル
化率が９０％に到達する時間が目安になる。すなわち、
本発明の方法で製造されるフェライト粒子は、スピネル
化率が９０％以上となる最低温度が７４０℃以下であ
る。In the method of the present invention, the above mixture is calcined to obtain ferrite particles. The calcination temperature is 740 ° C or lower, and more preferably 700 ° C or lower. If it exceeds 740 ° C., grain growth proceeds during calcination, which deteriorates the pulverizability of ferrite particles. The timing for finishing the calcination is the time when the spinelization rate reaches 90%. That is,
The ferrite particles produced by the method of the present invention have a minimum temperature of 740 ° C. or lower at which the spinelization rate becomes 90% or more.
【００２７】仮焼後のフェライト粒子は、必要に応じて
通常の粉砕機を用いて粉砕してもよい。本発明の方法で
製造されるフェライト粒子は、粒径が小さく、凝集が少
ないため、粉砕性が優れている。本発明の方法で製造さ
れるフェライト粒子は、仮焼後の比表面積が、３．５ｍ
2 ／ｇと大きく、チップインダクタのような小型磁気素
子を製造に使用する上で優れた特性を有している。本発
明の方法で製造されたフェライト粒子は、例えば、バイ
ンダーと混合してペーストとした後、印刷法やドクター
ブレード法などで磁性材層を形成させ、焼成後、積層チ
ップインダクタ等とすることができる。The ferrite particles after calcination may be pulverized by using an ordinary pulverizer, if necessary. The ferrite particles produced by the method of the present invention have a small particle size and a small amount of agglomeration, and thus have excellent grindability. The ferrite particles produced by the method of the present invention have a specific surface area of 3.5 m after calcination.
It is as large as 2 / g and has excellent characteristics when used in the manufacture of small magnetic elements such as chip inductors. The ferrite particles produced by the method of the present invention may be mixed with a binder to form a paste, and then a magnetic material layer may be formed by a printing method or a doctor blade method, and after firing, a laminated chip inductor or the like may be obtained. it can.
【００２８】[0028]
【実施例】以下、実施例により本発明の方法をさらに説
明する。なお、実施例において、酸化鉄の評価は、以下
の方法により実施した。比表面積は、ＢＥＴ法により測
定した。４５μｍ以上の凝集粒子（２次粒子）の比率評
価は、１００ｇの紛体を３００ｍｌの純水と混合して、
１時間振盪させてスラリー化した後、目開き４５μｍの
篩を用いて湿式分級し、篩上に残った残分を１００℃で
乾燥した後に重量測定し、初期粉体量を割り算して算出
した。一次粒子の平均粒径は、透過型電子顕微鏡写真上
の粒子２００個の粒径を測定し、個数平均粒径として見
積った。EXAMPLES The method of the present invention will be further described below with reference to examples. In the examples, iron oxide was evaluated by the following method. The specific surface area was measured by the BET method. To evaluate the ratio of aggregated particles (secondary particles) of 45 μm or more, 100 g of powder was mixed with 300 ml of pure water,
After shaking for 1 hour to form a slurry, wet classification was performed using a sieve having an opening of 45 μm, and the residue remaining on the sieve was dried at 100 ° C. and then weighed, and the initial amount of powder was calculated by division. . The average particle size of the primary particles was estimated as the number average particle size by measuring the particle size of 200 particles on a transmission electron micrograph.
【００２９】（実施例１）塩化第一鉄溶液と塩化第二鉄
溶液を溶液中のＦｅ3+濃度がＦｅ3+／Ｔｏｔａｌ- Ｆｅ
＝７質量％になるように混合し、水を加えて全Ｆｅ濃度
２．１ｍｏｌ／ｌ、溶液量１０リットルに調製した。ま
ず、内容積３０リットルの容器に、２．３ｍｏｌ／ｌの
ＮａＯＨ溶液２０リットルを入れ、そこに窒素ガスを通
気し攪拌しながら上記の塩化鉄溶液を混合した。この溶
液を窒素雰囲気のまま８５℃まで昇温し、温度が安定し
た後、空気を１０ｌ／ｍｉｎ通気して酸化を行いＦｅ3
Ｏ4 粒子を合成した。反応が終了した後、一般的な方法
で脱塩、ろ過、乾燥、解砕してＦｅ3 Ｏ4 粉末を得た。
この粉末を４８０℃で１時間加熱酸化して酸化鉄（α−
Ｆｅ2 Ｏ3 ）とし、粉砕機で粉砕し、分級して粗大な粒
子を除去して酸化鉄粉末を得た。得られた粉末の比表面
積は１０．５ｍ2 ／ｇであった。この粉末を目開き４５
μｍの篩を用いて分級し、篩上に残った残分から４５μ
ｍ以上の凝集粒子の含有量を調べたところ、酸化鉄粉末
中１８質量％であった。次に、この酸化鉄粉末を用いて
フェライト粒子を作製した。フェライト粒子の試作は、
得られた酸化鉄粉末を用いてＦｅ2 Ｏ3 ：ＮｉＯ：Ｚｎ
Ｏ：ＣｕＯ＝４９：１１：３０：１０（モル比）になる
ように秤量し、これをボールミルで１時間混合した後、
乾燥させた。この混合物を所定の温度で２時間仮焼し
た。仮焼が終了した後、Ｘ線回折（ＸＲＤ）により、ス
ピネル相のピーク強度比からスピネル化率を求めた。次
に、仮焼温度を仮焼温度を変えて、２時間仮焼し、同様
にスピネル化率を求め、仮焼温度とスピネル化率の関係
を調査した。この関係から、スピネル化率が９０％以上
となる最低温度を求め、この温度を仮焼可能温度とし
た。次に、仮焼可能温度で２時間仮焼したフェライト粒
子（Ｆｅ2 Ｏ3 ：ＮｉＯ：ＺｎＯ：ＣｕＯ＝４９：１
１：３０：１０（モル比））をボールミルで粉砕を行
い、途中サンプリングしながら比表面積が６ｍ2 ／ｇと
なるまで粉砕を続けた。結果を表１に示した。表１にお
いて、仮焼後比表面積は、仮焼可能温度で２時間仮焼し
た後の比表面積をＢＥＴ法で測定した値であり、粉砕時
間は、フェライト粒子の比表面積が６ｍ2 ／ｇになるま
での粉砕時間である。Example 1 A solution of ferrous chloride and ferric chloride in which the Fe 3+ concentration was Fe 3+ / Total-Fe
= 7% by mass, and water was added to prepare a total Fe concentration of 2.1 mol / l and a solution amount of 10 liters. First, 20 liters of a 2.3 mol / l NaOH solution was placed in a container having an internal volume of 30 liters, and the above iron chloride solution was mixed with nitrogen gas by agitating the solution. The temperature of this solution was raised to 85 ° C. in a nitrogen atmosphere, and after stabilizing the temperature, air was blown at 10 l / min to oxidize Fe 3
O 4 particles were synthesized. After completion of the reaction, Fe 3 O 4 powder was obtained by desalting, filtering, drying and crushing by a general method.
This powder was heated and oxidized at 480 ° C. for 1 hour to form iron oxide (α-
Fe 2 O 3 ) was pulverized with a pulverizer and classified to remove coarse particles to obtain iron oxide powder. The specific surface area of the obtained powder was 10.5 m 2 / g. Open this powder 45
45μ from the residue left on the sieve
When the content of aggregated particles of m or more was examined, it was 18% by mass in the iron oxide powder. Next, ferrite particles were produced using this iron oxide powder. The trial manufacture of ferrite particles is
Using the obtained iron oxide powder, Fe 2 O 3 : NiO: Zn
O: CuO = 49: 11: 30: 10 (molar ratio) was weighed and mixed with a ball mill for 1 hour.
Dried. This mixture was calcined at a predetermined temperature for 2 hours. After the calcination was completed, the spinelization rate was determined from the peak intensity ratio of the spinel phase by X-ray diffraction (XRD). Next, the calcination temperature was changed and the calcination temperature was changed to calcination for 2 hours. Then, the spinelization rate was similarly obtained, and the relationship between the calcination temperature and the spinelization rate was investigated. From this relationship, the minimum temperature at which the spinelization rate becomes 90% or more was obtained, and this temperature was set as the calcinable temperature. Next, ferrite particles (Fe 2 O 3 : NiO: ZnO: CuO = 49: 1) calcined for 2 hours at a calcinable temperature.
1:30:10 (molar ratio)) was pulverized with a ball mill, and pulverization was continued while sampling during the process until the specific surface area reached 6 m 2 / g. The results are shown in Table 1. In Table 1, the specific surface area after calcination is a value obtained by measuring the specific surface area after calcination at a calcinable temperature for 2 hours by the BET method, and the crushing time was such that the specific surface area of ferrite particles was 6 m 2 / g. It is the crushing time until it becomes.
【００３０】（実施例２〜５、比較例１〜２）実施例１
と同条件で酸化鉄（α−Ｆｅ2 Ｏ3 ）を作製し、粉砕機
を用いて粉砕し、空気分級機を用いて分級点を変えなが
ら補集し、粒度の異なる酸化鉄粉末サンプルを試作し
た。以下、実施例１と同様な評価を行った。結果を表１
および表２に示した。(Examples 2-5, Comparative Examples 1-2) Example 1
Iron oxide (α-Fe 2 O 3 ) was prepared under the same conditions as above, crushed using a crusher, and collected while changing the classification point using an air classifier to make iron oxide powder samples with different particle sizes did. Hereinafter, the same evaluation as in Example 1 was performed. The results are shown in Table 1.
And shown in Table 2.
【００３１】実施例１〜５と比較例１〜２の結果から、
粒径４５μｍ以上の凝集体の含有量が酸化鉄粉末中２０
質量％以下である本発明の酸化鉄を用いると、低温で仮
焼でき、また粉砕性に優れたフェライト粒子が得られる
ことがわかる。From the results of Examples 1-5 and Comparative Examples 1-2,
The content of aggregates having a particle size of 45 μm or more is 20 in the iron oxide powder.
It can be seen that the use of the iron oxide of the present invention in an amount of not more than mass% makes it possible to obtain ferrite particles which can be calcined at a low temperature and have excellent grindability.
【００３２】（実施例６）硫酸第一鉄と硫酸第二鉄溶液
を溶液中のＦｅ3+濃度がＦｅ3+／Ｔｏｔａｌ- Ｆｅ＝２
０％になるように混合し、水を加えて全Ｆｅ濃度２．１
ｍｏｌ／ｌ、溶液量１０リットルに調製した。まず、内
容積３０リットルの容器に、２．５ｍｏｌ／ｌのＮａＯ
Ｈ溶液２０リットルを入れ、そこに窒素ガスを通気し攪
拌しながら上記の塩化鉄溶液を混合した。この溶液を窒
素雰囲気のまま９０℃まで昇温し、温度が安定した後、
空気を１０ｌ／ｍｉｎ通気して酸化を行いＦｅ3 Ｏ4 粒
子を合成した。反応が終了したのち、一般的な方法で脱
塩、ろ過、乾燥、解砕してＦｅ3 Ｏ4 粉末を得た。この
粉末を４８０℃で１時間加熱酸化して酸化鉄（α−Ｆｅ
2 Ｏ3 ）とし、粉砕機で粉砕し、分級して粗大粒子を除
去して酸化鉄粉末を得た。得られた酸化鉄粉末につい
て、実施例１と同様な評価を行った。結果を表１に示し
た。Example 6 A solution of ferrous sulfate and ferric sulfate in which the Fe 3+ concentration in the solution is Fe 3+ / Total-Fe = 2
Mix so that the concentration becomes 0%, and add water to make the total Fe concentration 2.1.
The mol / l was adjusted to a solution volume of 10 liters. First, in a container with an internal volume of 30 liters, 2.5 mol / l NaO
20 liters of H solution was put therein, and the above iron chloride solution was mixed therein with nitrogen gas being aerated and stirred. This solution was heated to 90 ° C. in a nitrogen atmosphere to stabilize the temperature,
Fe 3 O 4 particles were synthesized by aerating 10 l / min of air for oxidation. After the reaction was completed, desalting, filtration, drying and crushing were carried out by a general method to obtain Fe 3 O 4 powder. This powder is heated and oxidized at 480 ° C. for 1 hour to form iron oxide (α-Fe
2 O 3 ), pulverized with a pulverizer, and classified to remove coarse particles to obtain iron oxide powder. The iron oxide powder obtained was evaluated in the same manner as in Example 1. The results are shown in Table 1.
【００３３】（実施例７）硫酸第一鉄溶液と硫酸第二鉄
溶液を溶液中のＦｅ3+濃度がＦｅ3+／Ｔｏｔａｌ- Ｆｅ
＝１２％になるように混合し、水を加えて全Ｆｅ濃度
２．１ｍｏｌ／ｌ、溶液量１０リットルに調製した。ま
ず、内容積３０リットルの容器に、２．４ｍｏｌ／ｌの
ＮａＯＨ溶液２０リットルを入れ、そこに窒素ガスを通
気し攪拌しながら上記の塩化鉄溶液を混合した。この溶
液を窒素雰囲気のまま７５℃まで昇温し、温度が安定し
た後、空気を１０ｌ／ｍｉｎ通気して酸化を行いＦｅ3
Ｏ4 粒子を合成した。反応が終了したのち、一般的な方
法で脱塩、ろ過、乾燥、解砕してＦｅ3 Ｏ4 粉末を得
た。この粉末を２６０℃で２時間加熱酸化して酸化鉄
（γ−Ｆｅ2 Ｏ3 ）とし、粉砕機で粉砕し、分級して粗
大粒子を除去して酸化鉄粉末を得た。得られた酸化鉄粉
末について実施例１と同様な評価を行った。結果を表１
に示した。(Embodiment 7) The ferrous sulfate solution and the ferric sulfate solution were mixed so that the Fe 3+ concentration in the solution was Fe 3+ / Total-Fe.
= 12%, and water was added to prepare a total Fe concentration of 2.1 mol / l and a solution amount of 10 liters. First, 20 liters of a 2.4 mol / l NaOH solution was placed in a container having an internal volume of 30 liters, and the above iron chloride solution was mixed with nitrogen gas by agitating the solution. The temperature of this solution was raised to 75 ° C. in a nitrogen atmosphere, and after stabilizing the temperature, air was blown at 10 l / min to oxidize Fe 3
O 4 particles were synthesized. After the reaction was completed, desalting, filtration, drying and crushing were carried out by a general method to obtain Fe 3 O 4 powder. This powder was heated and oxidized at 260 ° C. for 2 hours to obtain iron oxide (γ-Fe 2 O 3 ), which was crushed by a crusher and classified to remove coarse particles to obtain iron oxide powder. The obtained iron oxide powder was evaluated in the same manner as in Example 1. The results are shown in Table 1.
It was shown to.
【００３４】（実施例８）内容積３０リットルの容器に
Ｆｅ濃度３．８ｍｏｌ／ｌの塩化第二鉄溶液１０リット
ルと８ｍｏｌ／ｌのＮａＯＨ溶液を混合してｐＨ５．０
のＦｅ（ＯＨ）3溶液を作製し、８０℃で３日間加熱し
てα−Ｆｅ2 Ｏ3 を合成した。反応が終了したのち、一
般的な方法で脱塩、ろ過、乾燥、解砕し、粉砕機で粉砕
し、分級して粗大粒子を除去して酸化鉄粉末を得た。得
られた酸化鉄粉末について、実施例１と同様な評価を行
った。結果を表１に示した。Example 8 In a container having an internal volume of 30 liters, 10 liters of ferric chloride solution having an Fe concentration of 3.8 mol / l and 8 mol / l NaOH solution were mixed to obtain a pH of 5.0.
Fe (OH) 3 solution of was prepared and heated at 80 ° C. for 3 days to synthesize α-Fe 2 O 3 . After the reaction was completed, desalting, filtration, drying, crushing, and crushing by a general method, crushing with a crusher and removal of coarse particles to obtain iron oxide powder. The iron oxide powder obtained was evaluated in the same manner as in Example 1. The results are shown in Table 1.
【００３５】（実施例９）内容積３０リットルの容器
に、１．４７ｍｏｌ／ｌのＮａＯＨ溶液２０リットルを
入れ、そこに窒素ガスを通気し攪拌しながらＦｅ濃度
１．０５ｍｏｌ／ｌ、溶液量１０リットルに調製した硫
酸第一鉄溶液を混合した。この溶液を窒素雰囲気のまま
３０℃で空気を１０ｌ／ｍｉｎ通気して酸化を行いα−
ＦｅＯＯＨ粒子を合成した。反応が終了したのち、一般
的な方法で脱塩、ろ過、乾燥、解砕してα−ＦｅＯＯＨ
粉末を得た。この粉末を２００℃で１時間加熱してα−
Ｆｅ2 Ｏ 3 とし、粉砕機で粉砕し、分級して粗大粒子を
除去して酸化鉄粉末を得た。得られた酸化鉄粉末につい
て、実施例１と同様な評価を行った。結果を表１に示し
た。(Example 9) Container having an internal volume of 30 liters
To 20 liters of 1.47 mol / l NaOH solution
Put it in, nitrogen gas is bubbled through it, and the Fe concentration
Sulfuric acid prepared to 1.05 mol / l and a solution volume of 10 liters
The ferrous acid solution was mixed. Leave this solution in a nitrogen atmosphere
Air is aerated at 30 ° C for 10 l / min to oxidize and α-
FeOOH particles were synthesized. After the reaction is complete,
Desalination, filtration, drying, and crushing by conventional methods to obtain α-FeOOH
A powder was obtained. This powder is heated at 200 ° C. for 1 hour and α-
Fe2O 3And crush it with a crusher and classify it to remove coarse particles.
Removal was performed to obtain iron oxide powder. About the obtained iron oxide powder
Then, the same evaluation as in Example 1 was performed. The results are shown in Table 1.
It was
【００３６】（比較例３）内容積３０リットルの容器
に、１．１５ｍｏｌ／ｌのＮａＯＨ溶液２０リットルを
入れ、そこに窒素ガスを通気し攪拌しながらＦｅ濃度
１．２ｍｏｌ／ｌ、溶液量１０リットルに調製した硫酸
第一鉄溶液を混合した。この溶液を窒素雰囲気のまま９
０℃まで昇温し、温度が安定した後、空気を５ｌ／ｍｉ
ｎ通気して酸化を行いＦｅ3 Ｏ4 粒子を合成した。反応
が終了したのち、一般的な方法で脱塩、ろ過、乾燥、解
砕してＦｅ3 Ｏ4 粉末を得た。この粉末を５００℃で１
時間加熱酸化して酸化鉄（α−Ｆｅ2 Ｏ3 ）とし、粉砕
機で粉砕し、分級して粗大粒子を除去して酸化鉄粉末を
得た。得られた酸化鉄粉末について、実施例１と同様な
評価を行った。結果を表２に示した。Comparative Example 3 20 L of a 1.15 mol / L NaOH solution was placed in a container having an internal volume of 30 L, and nitrogen gas was passed through the container to agitate the Fe concentration of 1.2 mol / L and the solution amount of 10 L. The ferrous sulfate solution prepared to 1 liter was mixed. Leave this solution in a nitrogen atmosphere 9
After raising the temperature to 0 ° C and stabilizing the temperature, air is added at 5 l / mi.
Fe 3 O 4 particles were synthesized by carrying out oxidation by passing n. After the reaction was completed, desalting, filtration, drying and crushing were carried out by a general method to obtain Fe 3 O 4 powder. This powder at 500 ℃ 1
Time heating oxidized by iron oxide (α-Fe 2 O 3) , it was pulverized with a pulverizer to obtain iron oxide powder to remove coarse particles were classified. The iron oxide powder obtained was evaluated in the same manner as in Example 1. The results are shown in Table 2.
【００３７】（比較例４）内容積３０リットルの容器
に、１．０５ｍｏｌ／ｌのＮａＯＨ溶液２０リットルを
入れ、そこに窒素ガスを通気し攪拌しながらＦｅ濃度
０．７５ｍｏｌ／ｌ、溶液量１０リットルに調製した硫
酸第一鉄溶液を混合した。この溶液を窒素雰囲気のまま
３０℃で空気を５ｌ／ｍｉｎ通気して酸化を行いα−Ｆ
ｅＯＯＨ粒子を合成した。反応が終了したのち、一般的
な方法で脱塩、ろ過、乾燥、解砕してα−ＦｅＯＯＨ粉
末を得た。この粉末を２５０℃で１時間加熱してα−Ｆ
ｅ2 Ｏ3とし、粉砕機で粉砕して、分級して酸化鉄粉末
を得た。得られた酸化鉄粉末について、実施例１と同様
な評価を行った。結果を表２に示した。(Comparative Example 4) 20 L of a 1.05 mol / L NaOH solution was placed in a container having an internal volume of 30 L, and nitrogen gas was bubbled through the container to agitate the Fe concentration of 0.75 mol / L and the solution amount of 10 L. The ferrous sulfate solution prepared to 1 liter was mixed. This solution was oxidized by aerating 5 l / min of air at 30 ° C. in a nitrogen atmosphere and α-F
eOOH particles were synthesized. After the reaction was completed, desalting, filtration, drying and crushing were carried out by a general method to obtain α-FeOOH powder. This powder is heated at 250 ° C. for 1 hour and α-F
e 2 O 3 , pulverized with a pulverizer, and classified to obtain iron oxide powder. The iron oxide powder obtained was evaluated in the same manner as in Example 1. The results are shown in Table 2.
【００３８】実施例６〜９と比較例３〜４の結果から、
比表面積が１０〜６０ｍ2 ／ｇの本発明の酸化鉄粉末を
用いることにより、仮焼温度を低減でき、粉砕性に優れ
たフェライト粒子が得られることがわかる。From the results of Examples 6-9 and Comparative Examples 3-4,
It can be seen that by using the iron oxide powder of the present invention having a specific surface area of 10 to 60 m 2 / g, the calcination temperature can be reduced and ferrite particles excellent in pulverizability can be obtained.
【００３９】（比較例５）噴霧焙焼法で製造した比表面
積４．８ｍ2 ／ｇの酸化鉄を用いて、実施例１と同様な
評価を行った。結果を表２に示した。実施例と比較例５
の結果から、本発明の酸化鉄粉末を用いると、例えば噴
霧焙焼法で作製した比表面積が小さい酸化鉄粉末に比べ
て、低温で仮焼でき、また粉砕性に優れたフェライト粒
子が得られることがわかる。Comparative Example 5 The same evaluation as in Example 1 was carried out using iron oxide having a specific surface area of 4.8 m 2 / g produced by the spray roasting method. The results are shown in Table 2. Example and Comparative Example 5
From the results, using the iron oxide powder of the present invention, as compared with iron oxide powder having a small specific surface area produced by, for example, a spray roasting method, it is possible to perform calcination at a low temperature and obtain ferrite particles having excellent grindability. I understand.
【００４０】（実施例１０〜１１、比較例６）実施例１
と同様の条件でＦｅ3 Ｏ4 粉末を得た。この粉末を所定
温度（２３０℃（実施例１０）、３５０℃（実施例１
１）で１時間加熱酸化してγ−Ｆｅ2 Ｏ 3 単相の酸化鉄
（実施例１０）またはα−Ｆｅ2 Ｏ3 相およびγ−Ｆｅ
2 Ｏ3 相の混合相の酸化鉄（実施例１１）を得た。これ
らの酸化鉄を実施例１と同様の条件で粉砕、分級して酸
化鉄粉末を得、実施例１と同様にフェライト粒子の評価
を行った。また、比較例６として、Ｆｅ3 Ｏ4 を加熱酸
化せずに用いて、同様な条件でフェライト粒子の評価を
実施した。これらの結果を、表３に示した。実施例１、
１０、１１および比較例６の結果から、α−Ｆｅ2 Ｏ3
単相、γ−Ｆｅ2 Ｏ3 単相、またはα−Ｆｅ2 Ｏ3 相お
よびγ−Ｆｅ2 Ｏ3 相の混合相である本発明の酸化鉄を
用いると、低温で仮焼することが可能で、粉砕性が優れ
たフェライト粒子を得られることがわかる。(Examples 10 to 11 and Comparative Example 6) Example 1
Fe under the same conditions as3OFourA powder was obtained. Prescribe this powder
Temperature (230 ° C (Example 10), 350 ° C (Example 1)
Γ-Fe after 1 hour heating and oxidation in 1)2O 3Single phase iron oxide
(Example 10) or α-Fe2O3Phase and γ-Fe
2O3A mixed phase iron oxide (Example 11) was obtained. this
These iron oxides were pulverized and classified under the same conditions as in Example 1 to obtain an acid.
Obtained iron oxide powder and evaluated ferrite particles in the same manner as in Example 1.
I went. Further, as Comparative Example 6, Fe3OFourHeating acid
Without evaluating, evaluate ferrite particles under similar conditions.
Carried out. The results are shown in Table 3. Example 1,
From the results of 10, 11 and Comparative Example 6, α-Fe2O3
Single phase, γ-Fe2O3Single phase or α-Fe2O3Ai
And γ-Fe2O3Iron oxide of the present invention, which is a mixed phase of
If used, it can be calcined at low temperature and has excellent pulverizability.
It can be seen that excellent ferrite particles can be obtained.
【００４１】[0041]
【表１】 [Table 1]
【００４２】[0042]
【表２】 [Table 2]
【００４３】[0043]
【表３】 [Table 3]
【００４４】[0044]
【発明の効果】本発明の酸化鉄粉末を用いると、仮焼温
度を下げることができ、粉砕性に優れたフェライト粒子
を得ることができる。本発明の方法で製造されるフェラ
イト粒子は、スピネル化率９０％以上となる最低温度が
低いため、仮焼温度を低くすることができ、また、比表
面積が３．５ｍ2 ／ｇと大きいためチップインダクタ等
の小型磁気素子の製造用として優れている。When the iron oxide powder of the present invention is used, the calcination temperature can be lowered and ferrite particles excellent in pulverizability can be obtained. Since the ferrite particles produced by the method of the present invention have a low minimum temperature at which the spinelization rate is 90% or more, the calcination temperature can be lowered, and the specific surface area is as large as 3.5 m 2 / g. Excellent for manufacturing small magnetic elements such as chip inductors.
フロントページの続き (72)発明者 池田 幸司 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社千葉製鉄所内 (72)発明者 槙石 幸雄 千葉県千葉市中央区川崎町１番地 川崎製 鉄株式会社千葉製鉄所内 Ｆターム(参考） 4G002 AA03 AA06 AB02 AD04 AE02 5E041 AB12 CA01 HB17 NN02 Continued front page (72) Inventor Koji Ikeda 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki Chiba Steel Works, Ltd. (72) Inventor Yukio Makiishi 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Made in Kawasaki Chiba Steel Works, Ltd. F-term (reference) 4G002 AA03 AA06 AB02 AD04 AE02 5E041 AB12 CA01 HB17 NN02
Claims (2)
3 一次粒子と、その凝集粒子からなる酸化鉄粉末であっ
て、 粒径４５μｍ以上の凝集粒子の含有量が前記酸化鉄粉末
中２０質量％以下であることを特徴とするチップインダ
クタ用酸化鉄粉末。1. Fe 2 O having an average particle size of 0.02 to 0.2 μm
3 Iron oxide powder composed of primary particles and aggregated particles thereof, wherein the content of aggregated particles having a particle size of 45 μm or more is 20% by mass or less in the iron oxide powder, and iron oxide powder for chip inductors .
3 一次粒子と、その凝集粒子からなる酸化鉄粉末であっ
て、粒径４５μｍ以上の凝集粒子の含有量が、前記酸化
鉄粉末中２０質量％以下である前記酸化鉄粉末に、必要
な他の金属化合物を混合して、仮焼することにより、ス
ピネル化率が９０％以上となる最低温度が７４０℃以下
で、仮焼後比表面積が３．５ｍ2 ／ｇ以上であるフェラ
イト粉末を製造する方法。2. Fe 2 O having an average particle size of 0.02 to 0.2 μm
3 An iron oxide powder composed of primary particles and aggregated particles thereof, wherein the content of the aggregated particles having a particle size of 45 μm or more in the iron oxide powder is 20% by mass or less, other necessary By mixing a metal compound and calcining, a ferrite powder having a minimum temperature at which the spinelization rate is 90% or more is 740 ° C. or less and a specific surface area after calcining is 3.5 m 2 / g or more is produced. Method.
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| CN105024063A (en) * | 2014-04-25 | 2015-11-04 | Tdk株式会社 | Negative electrode active material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
| WO2019176968A1 (en) * | 2018-03-16 | 2019-09-19 | 戸田工業株式会社 | Ni-zn-cu-based ferrite powder, sintered body, and ferrite sheet |
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2002
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|---|---|---|---|---|
| CN105024063A (en) * | 2014-04-25 | 2015-11-04 | Tdk株式会社 | Negative electrode active material for lithium ion secondary battery, negative electrode for lithium ion secondary battery, and lithium ion secondary battery |
| WO2019176968A1 (en) * | 2018-03-16 | 2019-09-19 | 戸田工業株式会社 | Ni-zn-cu-based ferrite powder, sintered body, and ferrite sheet |
| CN111788156A (en) * | 2018-03-16 | 2020-10-16 | 户田工业株式会社 | Ni-Zn-Cu ferrite powder, sintered body, and ferrite sheet |
| KR20200130811A (en) * | 2018-03-16 | 2020-11-20 | 도다 고교 가부시끼가이샤 | Ni-Zn-Cu ferrite powder, sintered body, ferrite sheet |
| JPWO2019176968A1 (en) * | 2018-03-16 | 2021-03-25 | 戸田工業株式会社 | Ni-Zn-Cu-based ferrite powder, sintered body, ferrite sheet |
| CN111788156B (en) * | 2018-03-16 | 2023-04-28 | 户田工业株式会社 | Ni-Zn-Cu ferrite powder, sintered body, and ferrite sheet |
| JP7406183B2 (en) | 2018-03-16 | 2023-12-27 | 戸田工業株式会社 | Ni-Zn-Cu ferrite powder, sintered body, ferrite sheet |
| KR102634603B1 (en) * | 2018-03-16 | 2024-02-08 | 도다 고교 가부시끼가이샤 | Ni-Zn-Cu based ferrite powder, sintered body, ferrite sheet |
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