JP2012097287A - Sintered particle and carrier for electrophotographic developers, developer for electrophotographies using the same, and producing method of sintered particle sintering particle - Google Patents
Sintered particle and carrier for electrophotographic developers, developer for electrophotographies using the same, and producing method of sintered particle sintering particle Download PDFInfo
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本発明は、焼結粒子及びそれを用いた電子写真現像剤用キャリア、電子写真用現像剤並びに焼結粒子の製造方法に関するものである。 The present invention relates to sintered particles, an electrophotographic developer carrier using the same, an electrophotographic developer, and a method for producing sintered particles.
電子写真方式を用いたファクシミリやプリンタ、複写機などの画像形成装置では、粉体のトナーを感光体上の静電潜像に付着させてトナー像として可視像化し、このトナー像を用紙等に転写した後、加熱・加圧して用紙等に溶融定着させている。ここで、現像剤としては、トナーのみからなる一成分系現像剤と、トナーとキャリアとからなる二成分系現像剤とに大別される。近年では、二成分系現像剤の方が、トナーの帯電制御が容易で、安定して高画質を得られ、高速現像が可能であることから広く用いられている。 In image forming apparatuses such as facsimiles, printers, and copiers using an electrophotographic system, powder toner is attached to an electrostatic latent image on a photosensitive member to make it visible as a toner image. After being transferred to the sheet, it is heated and pressed to melt and fix it on a sheet or the like. Here, the developer is roughly classified into a one-component developer composed only of toner and a two-component developer composed of toner and carrier. In recent years, two-component developers are more widely used because toner charge control is easier, high image quality can be stably obtained, and high-speed development is possible.
二成分系現像剤を用いた現像方式では、トナーとキャリアとを現像装置内で撹拌混合し、摩擦によってトナーを所定量まで帯電させる。そして、回転する現像スリーブに現像剤を供給し、現像スリーブ状で磁気ブラシを形成させて、磁気ブラシを介して感光体へトナーを電気的に移動させて感光体上の静電潜像を可視像化する。トナー移動後のキャリアは現像スリーブ上に残留し、現像装置内で再びトナーと混合される。このため、キャリアの特性として、磁気ブラシを形成する磁気特性と、所望の電荷をトナーに付与する帯電特性および繰り返し使用における耐久性が要求される。 In the developing method using a two-component developer, the toner and the carrier are stirred and mixed in the developing device, and the toner is charged to a predetermined amount by friction. Then, a developer is supplied to the rotating developing sleeve, a magnetic brush is formed in the shape of the developing sleeve, and the toner is electrically moved to the photosensitive member via the magnetic brush, so that an electrostatic latent image on the photosensitive member can be formed. Visualize. The carrier after the toner movement remains on the developing sleeve and is mixed with the toner again in the developing device. For this reason, as the characteristics of the carrier, magnetic characteristics for forming a magnetic brush, charging characteristics for imparting a desired charge to the toner, and durability in repeated use are required.
そこで、マグネタイトや各種フェライト等の磁性粒子の表面を樹脂で被覆したキャリアが一般に用いられているが、キャリア粒子同士の摩擦や衝突によって長期間の使用でキャリアの割れや欠けが発生し、発生した破片や微粒子が画像特性に影響を与えたり、現像装置内の部品に損傷を与えることがあった。 Therefore, a carrier in which the surface of magnetic particles such as magnetite and various ferrites is coated with a resin is generally used, but the carrier particles are cracked or chipped due to friction or collision between the carrier particles over a long period of use. Debris and fine particles may affect the image characteristics and damage the parts in the developing device.
このような不具合を解消するため、例えば特許文献１では、キャリアを燃焼炎中で球状化処理することにより粒子の流動性を向上させる技術が提案されている。また、特許文献２では、キャリアの焼結条件を最適化することにより粒子の物理的強度を向上させる技術が提案されている。 In order to solve such problems, for example, Patent Document 1 proposes a technique for improving the fluidity of particles by spheroidizing a carrier in a combustion flame. Patent Document 2 proposes a technique for improving the physical strength of particles by optimizing the carrier sintering conditions.
上記提案技術によれば、キャリアの耐久性をある程度向上させることができると考えられるものの、近年の画像形成装置の高速化に伴う、現像剤の撹拌速度及び搬送速度のアップを考慮すればさらなる耐久性の向上が望まれる。 According to the proposed technique, although it is considered that the durability of the carrier can be improved to some extent, if the increase in the stirring speed and the conveying speed of the developer accompanying the recent increase in the speed of the image forming apparatus is taken into consideration, the durability is further increased. Improvement of the property is desired.
本発明は、このような状況のもとでなされたものであり、その目的は、長期間の使用によっても割れや欠けが生じ難く耐久性に優れた焼結粒子及びその製造方法を提供することにある。 The present invention has been made under such circumstances, and an object of the present invention is to provide sintered particles having excellent durability that are less likely to be cracked or chipped even after long-term use, and a method for producing the same. It is in.
また本発明の目的は、安定して高画質を得ることができる電子写真現像剤用キャリア及び電子写真用現像剤を提供することにある。 Another object of the present invention is to provide an electrophotographic developer carrier and an electrophotographic developer that can stably obtain high image quality.
本発明者らは、焼結粒子の機械的強度について検討を重ねた結果、まず、粒子内部の空孔が焼結粒子の割れや欠けの起点となり、キャリアなどの焼結粒子の機械的強度を低下させることを突き止めた。キャリアなどに使用されているマグネタイト粒子のほとんどは、下記反応式（１）に示すように、Ｆｅ２Ｏ３（ヘマタイト）を還元することにより製造されている。この還元反応において酸素ガスが発生する。また還元剤として炭素を加えた場合には、下記反応式（２）に示すように、炭素との反応により炭酸ガスが発生する。これらの製造工程において発生したガスの一部が粒子内部に残留して空孔が形成されると考えられる。そこで、気体を発生させずにＦｅ３Ｏ４を製造すればよいとの着想を得た。 As a result of repeated investigations on the mechanical strength of the sintered particles, the present inventors first found that the pores inside the particles became the starting point for cracking or chipping of the sintered particles, and the mechanical strength of the sintered particles such as the carrier was reduced. I found out that it would decrease. Most of the magnetite particles used for carriers and the like are produced by reducing Fe 2 O 3 (hematite) as shown in the following reaction formula (1). In this reduction reaction, oxygen gas is generated. When carbon is added as a reducing agent, carbon dioxide gas is generated by reaction with carbon as shown in the following reaction formula (2). It is considered that a part of the gas generated in these manufacturing processes remains inside the particles to form vacancies. Therefore, the idea of producing Fe 3 O 4 without generating gas was obtained.
６Ｆｅ２Ｏ３ → ４Ｆｅ３Ｏ４ ＋ Ｏ２↑ ・・・・・・・・・（１）
３Ｆｅ２Ｏ３ ＋ Ｃ → ２Ｆｅ３Ｏ４ ＋ ＣＯ↑ ・・・・・・（２）
6Fe 2 O 3 → 4Fe 3 O 4 + O 2 ↑ (1)
3Fe 2 O 3 + C → 2Fe 3 O 4 + CO ↑ (2)
また一方、焼結粒子内部に金属鉄を存在させると、粒子内部に発生した応力が金属鉄によって緩和され、クラックの拡大が抑制されるとの知見を得た。 On the other hand, the present inventors have found that when metallic iron is present inside the sintered particles, the stress generated inside the particles is relaxed by the metallic iron and the expansion of cracks is suppressed.
本発明はこれらの着想及び知見に基づきなされたものであり、本発明に係る焼結粒子は、金属鉄とＦｅ３Ｏ４とを主成分とし、空隙率を５％以下としたことを特徴とする。 The present invention has been made on the basis of these ideas and findings, and the sintered particles according to the present invention are characterized in that the main component is metallic iron and Fe 3 O 4 and the porosity is 5% or less. To do.
ここで、焼結粒子の機械的強度を一層向上させる観点からは、粉末Ｘ線回折によるＦｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）が０．０５〜０．７０の範囲となるようにするのが好ましい。（Ｉ２／Ｉ１）は金属鉄の含有量と正の相関関係があり、焼結粒子における金属鉄の含有量の一つの指標となるものである。 Here, from the viewpoint of improving the mechanical strength of the sintered particles further, the ratio (I maximum peak value of the Fe 3 O 4 by powder X-ray diffraction (I 1) and the maximum peak value of the metallic iron (I 2) 2 / I 1 ) is preferably in the range of 0.05 to 0.70. (I 2 / I 1 ) has a positive correlation with the content of metallic iron and serves as one index of the content of metallic iron in the sintered particles.
また、ＢＥＴ法による比表面積が０．０９ｍ２／ｇ以下、かつ真比重が４．９５ｇ／ｃｍ３以上であるのが好ましい。 Moreover, it is preferable that the specific surface area by BET method is 0.09 m < 2 > / g or less, and a true specific gravity is 4.95 g / cm < 3 > or more.
さらに、飽和磁化は７０Ａ・ｍ２／ｋｇ〜１２０Ａ・ｍ２／ｋｇの範囲が好ましい。 Further, the saturation magnetization in the range of 70A · m 2 / kg~120A · m 2 / kg is preferred.
そしてまた、平均粒径は１０μｍ〜１００μｍの範囲が好ましい。 The average particle size is preferably in the range of 10 μm to 100 μm.
本発明によれば、前記のいずれかに記載の焼結粒子の表面を樹脂で被覆したことを特徴とする電子写真現像用キャリアが提供される。 According to the present invention, there is provided an electrophotographic developing carrier characterized in that the surface of the sintered particles described above is coated with a resin.
また本発明によれば、前記記載の電子写真現像用キャリアとトナーとを含むことを特徴とする電子写真用現像剤が提供される。 According to the present invention, there is provided an electrophotographic developer comprising the electrophotographic developer carrier described above and a toner.
さらに本発明によれば、金属鉄とＦｅ３Ｏ４との混合相又はＦｅ３Ｏ４の単相が生成するように調整された金属鉄の粉末原料とＦｅ２Ｏ３の粉末原料とを液中にて混合してスラリーを得る工程と、前記スラリーを噴霧乾燥して造粒物を得る工程と、得られた造粒物を焼成して焼結粒子を得る工程とを有することを特徴とする焼結粒子の製造方法が提供される。 Furthermore, according to the present invention, a liquid material of metallic iron and a raw material of Fe 2 O 3 adjusted so that a mixed phase of metallic iron and Fe 3 O 4 or a single phase of Fe 3 O 4 is formed are obtained. Characterized in that it comprises a step of mixing in to obtain a slurry, a step of spray-drying the slurry to obtain a granulated product, and a step of firing the obtained granulated product to obtain sintered particles. A method for producing sintered particles is provided.
本発明に係る焼結粒子は、長期間の使用によっても割れや欠けが生じにくく、耐久性に優れる。 The sintered particles according to the present invention are not easily cracked or chipped even after long-term use, and are excellent in durability.
本発明に係る電子写真現像剤用キャリア及び電子写真用現像剤によれば画像形成速度の高速化に対応することができると共に、安定して高画質を得ることができる。 According to the carrier for electrophotographic developer and the developer for electrophotography according to the present invention, it is possible to cope with an increase in image forming speed and to stably obtain high image quality.
本発明に係る製造方法によれば、長期間の使用によっても割れや欠けが生じ難く、耐久性に優れた焼結粒子を製造することができる。 According to the production method of the present invention, it is possible to produce sintered particles that are hardly cracked or chipped even after long-term use and have excellent durability.
本発明に係る焼結粒子についてまず説明する。本発明に係る焼結粒子の大きな特徴は、金属鉄とＦｅ３Ｏ４とを主成分とし、空隙率を５％以下としたことにある。焼結粒子中に金属鉄が存在することによって、粒子に生じたクラックの進展が金属鉄の有する靱性で抑制される。加えて、粒子中の空隙が少ないことによって粒子強度が向上し耐久性が高まる。 First, the sintered particles according to the present invention will be described. A major feature of the sintered particles according to the present invention is that the main component is metallic iron and Fe 3 O 4 and the porosity is 5% or less. By the presence of metallic iron in the sintered particles, the progress of cracks generated in the particles is suppressed by the toughness of metallic iron. In addition, since there are few voids in the particles, the particle strength is improved and durability is increased.
後述するように、焼結粒子の製造工程において、金属鉄とＦｅ３Ｏ４とを原料として焼結させると、後述の反応式（３）に示すとおり、反応に伴うガスが発生しない。このため、粒子内部に形成される空孔が従来に比べて格段に少なくなる。粒子強度の観点からは、粒子の空隙率はゼロであるのが好ましいが、実使用上は５％までである。より好ましくは３％以下であり、さらに好ましくは２％以下である。 As will be described later, when metal iron and Fe 3 O 4 are sintered as raw materials in the manufacturing process of the sintered particles, no gas is generated due to the reaction, as shown in reaction formula (3) described later. For this reason, the void | hole formed in particle | grains becomes markedly fewer compared with the past. From the viewpoint of particle strength, the void ratio of the particles is preferably zero, but is practically up to 5%. More preferably, it is 3% or less, More preferably, it is 2% or less.
また、焼結粒子における金属鉄の含有量は、粉末Ｘ線回折によるＦｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）との比（Ｉ２／Ｉ１）で表して０．０５〜０．７０の範囲であることが好ましい。（Ｉ２／Ｉ１）が０．０５未満であると、金属鉄の含有量が少なすぎて本発明の効果が充分に得られないおそれがある。他方、（Ｉ２／Ｉ１）が０．７０を超えると、粒子強度は向上するものの金属鉄の含有量が多すぎて飽和磁化σｓや保磁力Ｈｃなどの磁気特性が高くなり過ぎるおそれがある。より好ましい（Ｉ２／Ｉ１）の範囲は０．１０〜０．６０の範囲である。 The content of metallic iron in the sintered particles, the ratio of the maximum peak value of the Fe 3 O 4 by powder X-ray diffraction and (I 1) the maximum peak value of the metal iron (I 2) (I 2 / I 1 ) And preferably in the range of 0.05 to 0.70. If (I 2 / I 1 ) is less than 0.05, the content of metallic iron is too small and the effects of the present invention may not be sufficiently obtained. On the other hand, if (I 2 / I 1 ) exceeds 0.70, although the particle strength is improved, the content of metallic iron is too large, and magnetic properties such as saturation magnetization σs and coercive force Hc may be too high. . A more preferable range of (I 2 / I 1 ) is a range of 0.10 to 0.60.
本発明に係る焼結粒子は、ＢＥＴ法による比表面積が０．０９ｍ２／ｇ以下で、且つ真比重が４．９５ｇ／ｃｍ３以上であるのが好ましい。すなわち、粒子表面に窪みなどの凹凸がなく、しかも粒子内部が詰まった状態、換言すれば粒子内に空孔のすくない状態が好ましい。 The sintered particles according to the present invention preferably have a specific surface area by the BET method of 0.09 m 2 / g or less and a true specific gravity of 4.95 g / cm 3 or more. That is, it is preferable that the particle surface has no irregularities such as dents and the inside of the particle is clogged, in other words, a state where there are not many pores in the particle.
本発明に係る焼結粒子の飽和磁化σｓは７０Ａ・ｍ２／ｋｇ〜１２０Ａ・ｍ２／ｋｇの範囲が好ましい。飽和磁化σｓが７０Ａ・ｍ２／ｋｇ未満であると、例えば、焼結粒子をキャリア芯材として用いた場合に、感光体へのキャリアの付着が頻繁に起きるおそれがある。一方、飽和磁化σｓが１２０Ａ・ｍ２／ｋｇを超えると、磁気ブラシの穂が硬くなり、電子写真現像における画質低下を招くおそれがある。より好ましい飽和磁化σｓは８０Ａ・ｍ２／ｋｇ〜９５Ａ・ｍ２／ｋｇの範囲である。 Saturation magnetization σs of sintered particles of the present invention in the range of 70A · m 2 / kg~120A · m 2 / kg is preferred. When the saturation magnetization σs is less than 70 A · m 2 / kg, for example, when sintered particles are used as the carrier core material, there is a possibility that the carrier adheres frequently to the photoreceptor. On the other hand, when the saturation magnetization σs exceeds 120 A · m 2 / kg, the ears of the magnetic brush become hard, and there is a possibility that the image quality deteriorates in electrophotographic development. More preferred saturation magnetization σs is in the range of 80A · m 2 / kg~95A · m 2 / kg.
本発明に係る焼結粒子の平均粒径としては１０μｍ〜１００μｍの範囲が好ましい。焼結粒子の平均粒径が１０μｍ以上であることで、粒子のそれぞれに必要な磁力が確実に付与され、例えば、焼結粒子をキャリア芯材として用いた場合に、感光体へのキャリア付着が抑制されるようになる。一方、焼結粒子の平均粒径が１００μｍ以下であることで、画像特性を良好に保つことができるようになる。焼結粒子の平均粒径を上記範囲とするには、焼結粒子の製造工程中及び／又は製造工程後に篩等を用いて分級処理を行えばよい。また、粒度分布はシャープであるのが好ましい。 The average particle size of the sintered particles according to the present invention is preferably in the range of 10 μm to 100 μm. When the average particle diameter of the sintered particles is 10 μm or more, a necessary magnetic force is reliably imparted to each of the particles. For example, when the sintered particles are used as a carrier core material, carrier adhesion to the photoreceptor is prevented. It will be suppressed. On the other hand, when the average particle size of the sintered particles is 100 μm or less, the image characteristics can be kept good. In order to set the average particle diameter of the sintered particles within the above range, classification may be performed using a sieve or the like during and / or after the manufacturing process of the sintered particles. The particle size distribution is preferably sharp.
本発明の焼結粒子は各種用途に用いることができ、例えば、電子写真現像用キャリアや電磁波吸収材、電磁波シールド材用材料粉末、ゴム、プラスチック用充填材・補強材、ペンキ、絵具・接着剤用艶消材、充填材、補強材等として用いることができる。これらの中でも特に電子写真現像用キャリアとして好適に用いられる。 The sintered particles of the present invention can be used in various applications, for example, electrophotographic developing carriers, electromagnetic wave absorbing materials, electromagnetic shielding material powders, rubber, plastic fillers / reinforcing materials, paints, paints and adhesives. It can be used as a matting material, filler, reinforcing material, etc. Among these, it is particularly preferably used as a carrier for electrophotographic development.
本発明の焼結粒子の製造方法に特に限定はないが、以下に説明する本発明に係る製造方法で製造するのが好適である。 Although there is no limitation in particular in the manufacturing method of the sintered particle of this invention, manufacturing with the manufacturing method which concerns on this invention demonstrated below is suitable.
原料としてＦｅ２Ｏ３の粉末と金属鉄の粉末とを秤量して分散媒中に投入し混合してスラリーを作製する。本発明に係る製造方法では、後述する反応によって、ガスを発生させずにＦｅ３Ｏ４の単相又はＦｅ３Ｏ４と金属鉄との混合相を生成させる。したがって、金属鉄の配合量は、Ｆｅ３Ｏ４の単相を生成させる場合は、Ｆｅ２Ｏ３の１００重量部に対して８．７４重量部であり、Ｆｅ３Ｏ４と金属鉄との混合相を生成させる場合には、Ｆｅ２Ｏ３の１００重量部に対して８．７４重量部を超える量である。Ｆｅ２Ｏ３の粉末及び金属鉄の粉末は一般に工業用として入手できるものを用いればよいが、目的とする焼結粒子の粒径に対して十分に小さい粒径であることが望ましい。これらの原料粉末の好ましい粒径は５μｍ以下であり、より好ましくは１μｍ以下である。スラリーの固形分濃度は５０ｗｔ％〜９０ｗｔ％の範囲が望ましい。 As a raw material, Fe 2 O 3 powder and metallic iron powder are weighed, put into a dispersion medium, and mixed to prepare a slurry. In accordance with the present invention, by a reaction which will be described later, to produce a mixed phase of a single phase or Fe 3 O 4 and metallic iron Fe 3 O 4 without generating gas. Therefore, the amount of metallic iron, the case of generating a single phase of Fe 3 O 4, a 8.74 parts by weight per 100 parts by weight of Fe 2 O 3, and Fe 3 O 4 and metallic iron When the mixed phase is generated, the amount exceeds 8.74 parts by weight with respect to 100 parts by weight of Fe 2 O 3 . The Fe 2 O 3 powder and the metal iron powder may be those that are generally available for industrial use, but it is desirable that the particle size be sufficiently smaller than the particle size of the intended sintered particles. The preferable particle diameter of these raw material powders is 5 μm or less, more preferably 1 μm or less. The solid content concentration of the slurry is desirably in the range of 50 wt% to 90 wt%.
本発明で使用する分散媒としては水が好適である。分散媒には、Ｆｅ２Ｏ３の粉末及び金属鉄の粉末の他、必要によりバインダー、分散剤等を配合してもよい。バインダーとしては、例えば、ポリビニルアルコールが好適に使用できる。バインダーの配合量としてはスラリー中の濃度が０．５〜２ｗｔ％程度とするのが好ましい。また、分散剤としては、例えば、ポリカルボン酸アンモニウム等が好適に使用できる。分散剤の配合量としてはスラリー中の濃度が０．５〜２ｗｔ％程度とするのが好ましい。その他、潤滑剤や焼結促進剤等を配合してもよい。 Water is preferred as the dispersion medium used in the present invention. In addition to Fe 2 O 3 powder and metallic iron powder, a binder, a dispersant, and the like may be blended in the dispersion medium as necessary. For example, polyvinyl alcohol can be suitably used as the binder. The blending amount of the binder is preferably about 0.5 to 2 wt% in the slurry. Moreover, as a dispersing agent, polycarboxylate ammonium etc. can be used conveniently, for example. As the blending amount of the dispersant, the concentration in the slurry is preferably about 0.5 to 2 wt%. In addition, you may mix | blend a lubricant, a sintering accelerator, etc.
次に、以上のようにして作製されたスラリーを湿式粉砕する。例えば、ボールミルや振動ミルを用いて所定時間湿式粉砕する。粉砕後の原材料の平均粒径は５μｍ以下が好ましく、より好ましくは１μｍ以下である。振動ミルやボールミルには、所定粒径のメディアを内在させるのがよい。メディアの材質としては、鉄系のクロム鋼や酸化物系のジルコニア、チタニア、アルミナなどが挙げられる。粉砕工程の形態としては連続式及び回分式のいずれであってもよい。粉砕物の粒径は、粉砕時間や回転速度、使用するメディアの材質・粒径などによって調整される。 Next, the slurry produced as described above is wet pulverized. For example, wet grinding is performed for a predetermined time using a ball mill or a vibration mill. The average particle diameter of the raw material after pulverization is preferably 5 μm or less, more preferably 1 μm or less. The vibration mill or ball mill preferably contains a medium having a predetermined particle diameter. Examples of the material of the media include iron-based chromium steel and oxide-based zirconia, titania, and alumina. As a form of a grinding | pulverization process, any of a continuous type and a batch type may be sufficient. The particle size of the pulverized product is adjusted depending on the pulverization time and rotation speed, the material and particle size of the media used, and the like.
そして、粉砕されたスラリーを噴霧乾燥させて造粒する。具体的には、スプレードライヤーなどの噴霧乾燥機にスラリーを導入し、雰囲気中へ噴霧することによって球状に造粒する。噴霧乾燥時の雰囲気温度は１００〜３００℃の範囲が好ましい。これにより、粒径１０〜１００μｍの球状の造粒物が得られる。なお、得られた造粒物は、振動ふるい等を用いて、粗大粒子や微粉を除去し粒度分布をシャープなものとするのが望ましい。 Then, the pulverized slurry is spray-dried and granulated. Specifically, the slurry is introduced into a spray dryer such as a spray dryer, and granulated into a spherical shape by spraying into the atmosphere. The atmospheric temperature during spray drying is preferably in the range of 100 to 300 ° C. Thereby, the spherical granulated material with a particle size of 10-100 micrometers is obtained. In addition, it is desirable that the obtained granulated product has a sharp particle size distribution by removing coarse particles and fine powder using a vibration sieve or the like.
次に、造粒物を加熱炉に投入し焼成させて焼結粒子を生成させる。焼成工程における反応を下記反応式（３）に示す。かかる式から理解されるように、本発明の製造方法では焼成工程でガスが発生しないので、焼結粒子内にガスが残留することがなく、粒子強度を高めることができる。
４Ｆｅ２Ｏ３ ＋ Ｆｅ → ３Ｆｅ３Ｏ４ ・・・・・・・（３）
Next, the granulated product is put into a heating furnace and fired to generate sintered particles. The reaction in the firing step is shown in the following reaction formula (3). As can be understood from this formula, in the production method of the present invention, no gas is generated in the firing step, so that no gas remains in the sintered particles, and the particle strength can be increased.
4Fe 2 O 3 + Fe → 3Fe 3 O 4 (3)
なお、Ｆｅを過剰に配合した場合には、Ｆｅ２Ｏ３と反応しなかった金属鉄が粒子内に分散して存在することになる。前述のように、焼結粒子中に金属鉄が存在すると、焼結粒子に生じたクラックの進展を金属鉄が抑制し粒子強度がさらに高まる。 In addition, when Fe is blended excessively, metallic iron that has not reacted with Fe 2 O 3 is present in a dispersed manner in the particles. As described above, when metallic iron is present in the sintered particles, the metallic iron suppresses the progress of cracks generated in the sintered particles, and the particle strength is further increased.
焼成温度としては８００℃以上であれば焼結は進み、生成した焼結粒子の形状が維持される。焼結温度の好ましい上限値は１５００℃である。焼結温度が１５００℃以下であると、焼結粒子同士の過剰焼結が起こらず、異形粒子の発生が抑制されるからである。したがって、焼結温度としては８００〜１５００℃の範囲が好ましく、より好ましくは１１００〜１３００℃の範囲である。また、焼成時間としては１〜６時間の範囲が好ましい。そして、焼結温度から常温まで焼結粒子を徐々に冷却する。 If the firing temperature is 800 ° C. or higher, sintering proceeds and the shape of the generated sintered particles is maintained. A preferable upper limit of the sintering temperature is 1500 ° C. This is because, when the sintering temperature is 1500 ° C. or less, excessive sintering between the sintered particles does not occur, and generation of irregularly shaped particles is suppressed. Therefore, the sintering temperature is preferably in the range of 800 to 1500 ° C, more preferably in the range of 1100 to 1300 ° C. The firing time is preferably in the range of 1 to 6 hours. Then, the sintered particles are gradually cooled from the sintering temperature to room temperature.
また、加熱炉内には不活性ガスを供給して、加熱炉内の酸素濃度を１％以下とするのが好ましい。加熱炉内の酸素濃度を低く抑えることによって、生成されたＦｅ３Ｏ４の酸化分解を防止するためである。 Further, it is preferable to supply an inert gas into the heating furnace so that the oxygen concentration in the heating furnace is 1% or less. This is to prevent oxidative decomposition of the produced Fe 3 O 4 by keeping the oxygen concentration in the heating furnace low.
次に、焼結粒子が互いに固着している場合には必要により解砕する。具体的には、例えば、ハンマーミル等によって焼結粒子を解砕する。解砕工程の形態としては連続式及び回分式のいずれであってもよい。そして、必要により、粒径を所定範囲に揃えるため分級を行ってもよい。分級方法としては、風力分級や篩分級など従来公知の方法を用いることができる。また、風力分級機で１次分級した後、振動篩や超音波篩で粒径を所定範囲に揃えるようにしてもよい。さらに、分級工程後に、磁場選鉱機によって非磁性粒子を除去するようにしてもよい。 Next, when the sintered particles are fixed to each other, they are crushed as necessary. Specifically, for example, the sintered particles are crushed by a hammer mill or the like. As a form of a crushing process, any of a continuous type and a batch type may be sufficient. And if necessary, classification may be performed in order to make the particle size in a predetermined range. As a classification method, a conventionally known method such as air classification or sieve classification can be used. In addition, after primary classification with an air classifier, the particle size may be aligned within a predetermined range with a vibration sieve or an ultrasonic sieve. Furthermore, you may make it remove a nonmagnetic particle with a magnetic field separator after a classification process.
以上のようにして作製した本発明の焼結粒子を、電子写真現像用キャリアとして用いる場合、焼結粒子をそのまま電子写真現像用キャリアとして用いることもできるが、帯電性等の観点からは、焼結粒子の表面を樹脂で被覆して用いるのが好ましい。 When the sintered particles of the present invention prepared as described above are used as a carrier for electrophotographic development, the sintered particles can be used as they are as a carrier for electrophotographic development. It is preferable to use the particles by coating the surface of the particles with a resin.
焼結粒子の表面を被覆する樹脂としては、従来公知のものが使用でき、例えば、ポリエチレン、ポリプロピレン、ポリ塩化ビニル、ポリ−４−メチルペンテン−１、ポリ塩化ビニリデン、ＡＢＳ（アクリロニトリル−ブタジエン−スチレン）樹脂、ポリスチレン、（メタ）アクリル系樹脂、ポリビニルアルコール系樹脂、並びにポリ塩化ビニル系やポリウレタン系、ポリエステル系、ポリアミド系、ポリブタジエン系等の熱可塑性エストラマー、フッ素シリコーン系樹脂などが挙げられる。 Conventionally known resins can be used for coating the surface of the sintered particles, such as polyethylene, polypropylene, polyvinyl chloride, poly-4-methylpentene-1, polyvinylidene chloride, ABS (acrylonitrile-butadiene-styrene). ) Resin, polystyrene, (meth) acrylic resin, polyvinyl alcohol resin, polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, and other thermoplastic elastomers, and fluorosilicone resins.
焼結粒子の表面を樹脂で被覆するには、樹脂の溶液又は分散液を焼結粒子に施せばよい。塗布溶液用の溶媒としては、トルエン、キシレン等の芳香族炭化水素系溶媒；アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン系溶媒；テトラヒドロフラン、ジオキサン等の環状エーテル類溶媒；エタノール、プロパノール、ブタノール等のアルコール系溶媒；エチルセロソルブ、ブチルセロソルブ等のセロソルブ系溶媒；酢酸エチル、酢酸ブチル等のエステル系溶媒；ジメチルホルムアミド、ジメチルアセトアミド等のアミド系溶媒などの１種又は２種以上を用いることができる。塗布溶液中の樹脂成分濃度は、一般に０．００１〜３０ｗｔ％、特に０．００１〜２ｗｔ％の範囲内にあるのがよい。 In order to coat the surface of the sintered particles with the resin, a resin solution or dispersion may be applied to the sintered particles. Solvents for the coating solution include aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; ethanol, propanol, and butanol Alcohol solvents such as ethyl cellosolve, cellosolve solvents such as butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate; amide solvents such as dimethylformamide and dimethylacetamide, etc. . The concentration of the resin component in the coating solution is generally in the range of 0.001 to 30 wt%, particularly 0.001 to 2 wt%.
焼結粒子への樹脂の被覆方法としては、例えばスプレードライ法や流動床法あるいは流動床を用いたスプレードライ法、浸漬法等を用いることができる。これらの中でも、少ない樹脂量で効率的に塗布できる点で流動床法が特に好ましい。樹脂被覆量は、例えば流動床法の場合には吹き付ける樹脂溶液量や吹き付け時間によって調整することができる。 As a method of coating the sintered particles with the resin, for example, a spray drying method, a fluidized bed method, a spray drying method using a fluidized bed, an immersion method, or the like can be used. Among these, the fluidized bed method is particularly preferable in that it can be efficiently applied with a small amount of resin. For example, in the case of the fluidized bed method, the resin coating amount can be adjusted by the amount of resin solution sprayed and the spraying time.
本発明に係る電子写真用現像剤は、以上のようにして作製した電子写真現像用キャリアとトナーとを混合してなる。電子写真現像用キャリアとトナーとの混合比に特に限定はなく、使用する現像装置の現像条件などから適宜決定すればよい。一般に現像剤中のトナー濃度は１ｗｔ％〜２０ｗｔ％の範囲が好ましい。トナー濃度が１ｗｔ％未満の場合、画像濃度が薄くなりすぎ、他方トナー濃度が２０ｗｔ％を超える場合、現像装置内でトナー飛散が発生し機内汚れや転写紙などの背景部分にトナーが付着する不具合が生じるおそれがあるからである。より好ましいトナー濃度は３〜１５ｗｔ％の範囲である。 The electrophotographic developer according to the present invention is obtained by mixing the electrophotographic developer carrier prepared as described above and a toner. The mixing ratio of the electrophotographic developing carrier and the toner is not particularly limited, and may be appropriately determined from the developing conditions of the developing device to be used. Generally, the toner concentration in the developer is preferably in the range of 1 wt% to 20 wt%. When the toner density is less than 1 wt%, the image density becomes too low, and when the toner density exceeds 20 wt%, the toner scatters in the developing device, and the toner adheres to the background portion such as internal dirt or transfer paper. This is because there is a risk of occurrence. A more preferable toner concentration is in the range of 3 to 15 wt%.
電子写真現像用キャリアとトナーとの混合は、従来公知の混合装置を用いることができる。例えばヘンシェルミキサー、Ｖ型混合機、タンブラーミキサー、ハイブリタイザー等を用いることができる。 For mixing the electrophotographic carrier and the toner, a conventionally known mixing device can be used. For example, a Henschel mixer, a V-type mixer, a tumbler mixer, a hybridizer, or the like can be used.
以下、本発明を実施例によりさらに詳しく説明するが本発明はこれらの例に何ら限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples at all.
実施例１
原料として、平均粒径が０．６μｍのＦｅ２Ｏ３の粉末１０ｋｇと、平均粒径が５．０μｍの金属鉄の粉末１ｋｇとを純水３．０ｋｇ中に分散し、分散剤としてポリカルボン酸アンモニウム系分散剤を６０ｇ添加して混合物とした。この混合物を湿式ボールミル（メディア径２ｍｍ）により粉砕処理し、混合スラリーを得た。
Example 1
As raw materials, 10 kg of Fe 2 O 3 powder having an average particle diameter of 0.6 μm and 1 kg of metal iron powder having an average particle diameter of 5.0 μm are dispersed in 3.0 kg of pure water, and polycarboxylic acid is used as a dispersant. 60 g of an acid ammonium dispersant was added to form a mixture. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry.
この混合スラリーをスプレードライヤーにて約１３０℃の熱風中に噴霧し（ディスク回転数２０，０００ｒｐｍ）、粒径１０〜１００μｍの乾燥造粒物を得た。この造粒物から、網目９１μｍの篩網を用いて粗粒を分離し、網目３７μｍの篩網を用いて微粒を分離した。 This mixed slurry was sprayed into hot air of about 130 ° C. with a spray dryer (disk rotation speed: 20,000 rpm) to obtain a dry granulated product having a particle size of 10 to 100 μm. From this granulated product, coarse particles were separated using a sieve mesh having a mesh size of 91 μm, and fine particles were separated using a sieve mesh having a mesh size of 37 μm.
この造粒粉を、窒素雰囲気下の電気炉に投入し１２００℃で３時間焼成した。得られた焼結粒子をハンマーミルで解砕した後に振動ふるいを用いて分級し、平均粒径５０μｍの焼結粒子を得た。図１に焼結粒子のＳＥＭ写真、図２に焼結粒子の断面ＳＥＭ写真をそれぞれ示す。また、得られた焼結粒子の粉体Ｘ線回折（「ＸＲＤ」X-ray diffraction）分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。さらに、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を下記に示す方法で測定した。図５に、粉末Ｘ線回折分析の結果を示し、表１にその他の測定結果をまとめて示す。 This granulated powder was put into an electric furnace under a nitrogen atmosphere and fired at 1200 ° C. for 3 hours. The obtained sintered particles were pulverized with a hammer mill and then classified using a vibration sieve to obtain sintered particles having an average particle diameter of 50 μm. FIG. 1 shows an SEM photograph of the sintered particles, and FIG. 2 shows a cross-sectional SEM photograph of the sintered particles. Further, the powder X-ray diffraction of the obtained sintered particles were ( "XRD" X-ray diffraction) analysis, the maximum peak value of the Fe 3 O 4 (I 1) and the maximum peak value of the metallic iron (I 2) The ratio (I 2 / I 1 ) was calculated. Furthermore, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the following methods. FIG. 5 shows the results of powder X-ray diffraction analysis, and Table 1 summarizes other measurement results.
（粉体Ｘ線回折分析）
Ｘ線回折分析装置（リガク社製「ＵＬＴＩＭＡIV」）を用いてＸＲＤパターンを測定した。Ｘ線源は銅を使用し、加速電圧４０ｋＶ、電流３０ｍＡでＸ線を発生させた。粉末Ｘ線の測定条件は走査モード：連続測定、発散スリット：１／２°、散乱スリット：１／２°、受光スリット：０．１５ｍｍ、回転速度：５．０ｒｐｍ、測定角度：１５°≦２θ≦９５°、測定間隔：０．０２°、走査速度：１．０°／分で測定を行った。
(Powder X-ray diffraction analysis)
The XRD pattern was measured using an X-ray diffraction analyzer (“ULTIMA IV” manufactured by Rigaku Corporation). The X-ray source used copper, and X-rays were generated at an acceleration voltage of 40 kV and a current of 30 mA. The measurement conditions of the powder X-ray are scanning mode: continuous measurement, divergence slit: 1/2 °, scattering slit: 1/2 °, light receiving slit: 0.15 mm, rotation speed: 5.0 rpm, measurement angle: 15 ° ≦ 2θ ≦ 95 °, measurement interval: 0.02 °, scanning speed: 1.0 ° / min.
（空隙率）
焼結粒子を熱硬化性の樹脂に分散させた状態で硬化させ、クロスセクションポリッシャー（日本電子株式会社製、ＳＭ−０９０１０）により樹脂を切断することで焼結粒子の断面観察用の試料を作成した。倍率１０００倍の断面ＳＥＭ写真を用いて、粒子の空孔部分とその他の部分とを階調により分離し、空孔部分の面積率を算出した。５０個の粒子の面積率を測定しその平均を空隙率とした。なお、断面ＳＥＭ写真における粒子の空孔部分とその他の部分との階調による分離及び面積率の計算は、画像解析ソフト（Soft Imaging System GmbH社、「analysis」）を用いた。
(Porosity)
The sintered particles are cured in a state where they are dispersed in a thermosetting resin, and the cross section polisher (manufactured by JEOL Ltd., SM-09010) is cut to prepare a sample for observing the cross section of the sintered particles. did. Using a cross-sectional SEM photograph at a magnification of 1000 times, the pore portions of the particles and other portions were separated by gradation, and the area ratio of the pore portions was calculated. The area ratio of 50 particles was measured and the average was taken as the porosity. In addition, image analysis software (Soft Imaging System GmbH, “analysis”) was used for separation of the pores of the particles in the cross-sectional SEM photograph and other parts by gradation and calculation of the area ratio.
（比表面積）
焼結粒子の比表面積は、マウンテック社製「Macsorb(Model:1208」を用いてＢＥＴ法により測定した。吸着ガスは窒素を用い、キャリアガスはヘリウムを用いた。
(Specific surface area)
The specific surface area of the sintered particles was measured by the BET method using “Macsorb (Model: 1208)” manufactured by Mountec Co., Ltd. Nitrogen was used as the adsorption gas and helium was used as the carrier gas.
（真比重）
焼結粒子の真比重は、Quantachrome社製「ULTRA PYCNOMETER 1000」を用いて測定した。
(True specific gravity)
The true specific gravity of the sintered particles was measured using “ULTRA PYCNOMETER 1000” manufactured by Quantachrome.
（磁気特性）
室温専用振動試料型磁力計（ＶＳＭ）（東英工業社製「ＶＳＭ−Ｐ７」）を用いて磁化の測定を行い、印加磁界７９５．８ｋＡ／ｍ（１０００Ｏｅ）の磁場における飽和磁化σＳ及び保磁力Ｈｃをそれぞれ測定した。
(Magnetic properties)
Perform the measurement of the magnetization by using a room temperature-only vibrating sample magnetometer (VSM) (manufactured by Toei Kogyo Co., Ltd. "VSM-P7"), the saturation magnetization sigma S and coercive in the magnetic field of the applied magnetic field 795.8 kA / m (1000 Oe) The magnetic force Hc was measured.
（強度指数）
サンプルミル（協立理工社製「ＳＫ−Ｍ１０」）に試料１００ｇを投入し、回転数１６０００ｒｐｍで４０秒間粉砕処理した後、処理前後の焼結粒子の平均粒径を測定し、下記式から強度指数を算出した。この値が１．０に近いほど粉砕処理によって粒子の割れや欠けが発生せず、機械的強度が高い。
強度指数＝（処理後の平均粒径）／（処理前の平均粒径）
なお、焼結粒子の平均粒径は、日機装株式会社製のマイクロトラック、Ｍｏｄｅｌ９３２０−Ｘ１００を用いて測定した、体積率５０％までの積算粒径とした。
(Strength index)
A sample mill (“SK-M10” manufactured by Kyoritsu Riko Co., Ltd.) was charged with 100 g of sample, ground for 40 seconds at a rotational speed of 16000 rpm, the average particle size of sintered particles before and after the treatment was measured, The index was calculated. The closer this value is to 1.0, the higher the mechanical strength is because the particles are not cracked or chipped by the grinding treatment.
Strength index = (average particle size after treatment) / (average particle size before treatment)
The average particle size of the sintered particles was an integrated particle size up to a volume ratio of 50% as measured using Microtrack, Model 9320-X100 manufactured by Nikkiso Co., Ltd.
実施例２
焼結温度を１３００℃とした以外は実施例１と同様にして焼結粒子を作製した。そして作製した焼結粒子について、実施例１と同様にして、ＸＲＤ分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。また、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を前記方法で測定した。図５に、粉末Ｘ線回折分析の結果を示し、表１にその他の測定結果をまとめて示す。
Example 2
Sintered particles were produced in the same manner as in Example 1 except that the sintering temperature was 1300 ° C. And for sintered particles prepared in the same manner as in Example 1, subjected to XRD analysis, the ratio of the maximum peak value of the Fe 3 O 4 (I 1) and the maximum peak value of the metallic iron (I 2) (I 2 / I 1 ) was calculated. Further, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the above methods. FIG. 5 shows the results of powder X-ray diffraction analysis, and Table 1 summarizes other measurement results.
実施例３
金属鉄の配合量を２ｋｇとした以外は実施例１と同様にして焼結粒子を作製した。そして作製した焼結粒子について、実施例１と同様にして、ＸＲＤ分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。また、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を前記方法で測定した。図５に、粉末Ｘ線回折分析の結果を示し、表１にその他の測定結果をまとめて示す。
Example 3
Sintered particles were produced in the same manner as in Example 1 except that the amount of metallic iron was 2 kg. And for sintered particles prepared in the same manner as in Example 1, subjected to XRD analysis, the ratio of the maximum peak value of the Fe 3 O 4 (I 1) and the maximum peak value of the metallic iron (I 2) (I 2 / I 1 ) was calculated. Further, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the above methods. FIG. 5 shows the results of powder X-ray diffraction analysis, and Table 1 summarizes other measurement results.
実施例４
金属鉄の配合量を２ｋｇとし、焼結温度を１３００℃とした以外は実施例１と同様にして焼結粒子を作製した。そして作製した焼結粒子について、実施例１と同様にして、ＸＲＤ分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。また、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を前記方法で測定した。図５に、粉末Ｘ線回折分析の結果を示し、表１にその他の測定結果をまとめて示す。
Example 4
Sintered particles were produced in the same manner as in Example 1 except that the amount of metallic iron was 2 kg and the sintering temperature was 1300 ° C. And for sintered particles prepared in the same manner as in Example 1, subjected to XRD analysis, the ratio of the maximum peak value of the Fe 3 O 4 (I 1) and the maximum peak value of the metallic iron (I 2) (I 2 / I 1 ) was calculated. Further, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the above methods. FIG. 5 shows the results of powder X-ray diffraction analysis, and Table 1 summarizes other measurement results.
実施例５
金属鉄の配合量を３ｋｇとした以外は実施例１と同様にして焼結粒子を作製した。そして作製した焼結粒子について、実施例１と同様にして、ＸＲＤ分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。また、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を前記方法で測定した。図５に、粉末Ｘ線回折分析の結果を示し、表１にその他の測定結果をまとめて示す。
Example 5
Sintered particles were produced in the same manner as in Example 1 except that the amount of metallic iron was 3 kg. And for sintered particles prepared in the same manner as in Example 1, subjected to XRD analysis, the ratio of the maximum peak value of the Fe 3 O 4 (I 1) and the maximum peak value of the metallic iron (I 2) (I 2 / I 1 ) was calculated. Further, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the above methods. FIG. 5 shows the results of powder X-ray diffraction analysis, and Table 1 summarizes other measurement results.
比較例１
金属鉄を配合しなかった以外は実施例１と同様にして焼結粒子を作製した。図３に焼結粒子のＳＥＭ写真、図４に焼結粒子の断面ＳＥＭ写真をそれぞれ示す。また、実施例１と同様にして、ＸＲＤ分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。さらに、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を前記方法で測定した。図５に、粉末Ｘ線回折分析の結果を示し、表１にその他の測定結果をまとめて示す。
Comparative Example 1
Sintered particles were produced in the same manner as in Example 1 except that no metallic iron was added. FIG. 3 shows an SEM photograph of the sintered particles, and FIG. 4 shows a cross-sectional SEM photograph of the sintered particles. In the same manner as in Example 1, subjected to XRD analysis, was calculated the maximum peak value of the Fe 3 O 4 and (I 1) the maximum peak value of the metal iron ratio of (I 2) (I 2 / I 1) . Furthermore, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the above methods. FIG. 5 shows the results of powder X-ray diffraction analysis, and Table 1 summarizes other measurement results.
比較例２
金属鉄を配合せず、焼結温度を１０００℃とした以外は実施例１と同様にして焼結粒子を作製した。そして作製した焼結粒子について、実施例１と同様にして、ＸＲＤ分析を行い、Ｆｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）を算出した。また、焼結粒子の空隙率、比表面積、真比重、磁気特性、強度指数を前記方法で測定した。表１に測定結果をまとめて示す。
Comparative Example 2
Sintered particles were produced in the same manner as in Example 1 except that metallic iron was not blended and the sintering temperature was 1000 ° C. And for sintered particles prepared in the same manner as in Example 1, subjected to XRD analysis, the ratio of the maximum peak value of the Fe 3 O 4 (I 1) and the maximum peak value of the metallic iron (I 2) (I 2 / I 1 ) was calculated. Further, the porosity, specific surface area, true specific gravity, magnetic properties, and strength index of the sintered particles were measured by the above methods. Table 1 summarizes the measurement results.
本発明に係る焼結粒子である実施例１〜５の焼結粒子は、図１及び図２のＳＥＭ写真から理解されるように、粒子表面は滑らかで凹凸が少なく、しかも粒子内の空孔も少なかった。具体的には、表１から明らかなように、実施例１〜５の焼結粒子は空隙率が２．８以下で、比表面積は０．０７ｍ２／ｇ以下、真比重は４．９５ｇ／ｃｍ３以上であった。加えてＦｅ３Ｏ４の最大ピーク値（Ｉ１）と金属鉄の最大ピーク値（Ｉ２）の比（Ｉ２／Ｉ１）が０．１１１〜０．５０４の範囲と、金属鉄の含有量が好適範囲であるので、飽和磁化σｓ及び保磁力Ｈｃは実使用上問題のない範囲の値に抑えられ、且つ焼結粒子の強度指数は０．８０以上と高い強度を示した。 As understood from the SEM photographs of FIGS. 1 and 2, the sintered particles of Examples 1 to 5, which are the sintered particles according to the present invention, have a smooth particle surface with little unevenness, and voids in the particles. There were few. Specifically, as apparent from Table 1, the sintered particles of Examples 1 to 5 have a porosity of 2.8 or less, a specific surface area of 0.07 m 2 / g or less, and a true specific gravity of 4.95 g / cm 3 or more. In addition, the ratio (I 2 / I 1 ) of the maximum peak value (I 1 ) of Fe 3 O 4 and the maximum peak value (I 2 ) of metallic iron is in the range of 0.111 to 0.504, and the inclusion of metallic iron Since the amount is in a preferable range, the saturation magnetization σs and the coercive force Hc are suppressed to values in a range where there is no problem in practical use, and the strength index of the sintered particles shows a high strength of 0.80 or more.
これに対して、金属鉄を含有していない比較例１及び比較例２の焼結粒子は、空隙率が７．８％及び１２．４％と高く、強度指数は０．５８及び０．４０と粒子の割れや欠けが発生しやすいものであった。 In contrast, the sintered particles of Comparative Example 1 and Comparative Example 2 that do not contain metallic iron have high porosity of 7.8% and 12.4%, and the strength index is 0.58 and 0.40. In other words, cracking and chipping of the particles are likely to occur.
本発明に係る焼結粒子は、長期間の使用によっても割れや欠けが生じにくく、耐久性に優れ有用である。また、本発明に係る製造方法によれば、割れや欠けが生じにくいこのような焼結粒子を効率的に製造することができ有用である。 The sintered particles according to the present invention hardly break or chip even after long-term use, and are excellent in durability and useful. In addition, according to the production method of the present invention, such sintered particles that are less prone to cracking and chipping can be efficiently produced and useful.
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| JPS6230801A (en) * | 1985-07-31 | 1987-02-09 | Kawasaki Steel Corp | Ferromagnetic powder |
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| JPS6230801A (en) * | 1985-07-31 | 1987-02-09 | Kawasaki Steel Corp | Ferromagnetic powder |
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| EP3425072A4 (en) * | 2016-03-01 | 2019-09-25 | Hitachi Metals, Ltd. | Composite particles, composite powder, method for manufacturing composite particles, and method for manufacturing composite member |
| US10858295B2 (en) | 2016-03-01 | 2020-12-08 | Hitachi Metals, Ltd. | Composite particles, composite powder, method for manufacturing composite particles, and method for manufacturing composite member |
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