JP7433090B2 - Ferrite carrier core material, carrier for electrophotographic development and developer for electrophotography using the same - Google Patents

Ferrite carrier core material, carrier for electrophotographic development and developer for electrophotography using the same Download PDF

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JP7433090B2
JP7433090B2 JP2020040473A JP2020040473A JP7433090B2 JP 7433090 B2 JP7433090 B2 JP 7433090B2 JP 2020040473 A JP2020040473 A JP 2020040473A JP 2020040473 A JP2020040473 A JP 2020040473A JP 7433090 B2 JP7433090 B2 JP 7433090B2
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優樹 金城
啓太郎 赤井
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Dowa IP Creation Co Ltd
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本発明は、フェライトキャリア芯材並びにこれを用いた電子写真現像用キャリア及び電子写真用現像剤に関するものである。 The present invention relates to a ferrite carrier core material, a carrier for electrophotographic development, and a developer for electrophotography using the same.

例えば、電子写真方式を用いたファクシミリやプリンター、複写機などの画像形成装置では、感光体の表面に形成された静電潜像にトナーを付着させて可視像化し、この可視像を用紙等に転写した後、加熱・加圧して定着させている。高画質化やカラー化の観点から、現像剤としては、キャリアとトナーとを含むいわゆる二成分現像剤が広く使用されている。 For example, in image forming devices such as facsimiles, printers, and copiers that use electrophotography, toner is attached to an electrostatic latent image formed on the surface of a photoreceptor to make it visible, and this visible image is transferred to paper. After transferring the image onto a paper, etc., it is fixed by applying heat and pressure. From the viewpoint of high image quality and colorization, so-called two-component developers containing carrier and toner are widely used as developers.

二成分現像剤を用いた現像方式では、キャリアとトナーとが現像装置内で撹拌混合され、摩擦によってトナーが所定量まで帯電される。そして、回転する現像ローラに現像剤が供給され、現像ローラ上で磁気ブラシが形成して、磁気ブラシを介して感光体へトナーが電気的に移動して感光体上の静電潜像が可視像化される。トナー移動後のキャリアは現像ローラ上に残留し、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、現像ローラへの移動特性(くみ上げ性)、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などが要求される。 In a developing method using a two-component developer, carrier and toner are stirred and mixed in a developing device, and the toner is charged to a predetermined amount by friction. Then, developer is supplied to the rotating developing roller, a magnetic brush is formed on the developing roller, and the toner is electrically moved to the photoreceptor via the magnetic brush, forming an electrostatic latent image on the photoreceptor. Visualized. After the toner has been transferred, the carrier remains on the developing roller and is mixed with the toner again in the developing device. Therefore, characteristics of the carrier are required, such as transfer characteristics to the developing roller (pumping ability), magnetic characteristics to form a magnetic brush, charging characteristics to impart a desired charge to the toner, and durability for repeated use.

このようなキャリアとして、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ものが一般に用いられている。キャリア芯材としての磁性粒子には、良好な磁気的特性と共に、トナーに対する良好な摩擦帯電特性などが要求される。このような特性を満たすキャリア芯材として種々の形状のものが提案されている。 As such carriers, magnetic particles such as magnetite and various ferrites whose surfaces are coated with resin are generally used. The magnetic particles used as the carrier core material are required to have good magnetic properties as well as good triboelectric charging properties for toner. Various shapes of carrier core materials have been proposed that satisfy these characteristics.

例えば、現像メモリ(前画像の影響が後画像に表れる現象)等の抑制を目的として、ストロンチウム(Sr)及びケイ素(Si)が特定量含有され、粒子の最大山谷深さRz及びその標準偏差σが特定範囲であるマンガン(Mn)フェライト粒子をキャリア芯材として使用することが提案されている(特許文献1)。またロック型氷砂糖形状及び/又は牡蠣殻形状といった形状が極端に異形化したフェライト芯材も提案されている(特許文献2)。 For example, for the purpose of suppressing development memory (a phenomenon in which the influence of the previous image appears on the subsequent image), strontium (Sr) and silicon (Si) are contained in specific amounts, and the maximum peak-to-valley depth Rz and its standard deviation σ It has been proposed to use manganese (Mn) ferrite particles having a specific range of ferrite as a carrier core material (Patent Document 1). Further, a ferrite core material having an extremely irregular shape such as a rock-shaped rock candy shape and/or an oyster shell shape has also been proposed (Patent Document 2).

特開2017-031031号公報JP2017-031031A 特開2007-148452号公報Japanese Patent Application Publication No. 2007-148452

しかしながら、粒子の最大山谷深さRzを大きくすなわち粒子表面の凹凸化を進めることによって、キャリア芯材の表面を樹脂被覆した樹脂被覆キャリアにおいて、キャリア芯材の一部が表面に露出して樹脂被覆キャリアの電気抵抗が下がって現像メモリの発生はある程度抑制はされるものの、現像剤の現像ローラへのくみ上げ量及び現像領域への現像剤の搬送量が十分でない虞がある。また極端に異形化したキャリア芯材では、キャリアの粒子同士の引っ掛かりが強くなる結果、現像ローラ表面に形成される磁気ブラシが硬くなって感光体表面が磁気ブラシの摺擦によって傷つけられる虞がある。 However, in a resin-coated carrier in which the surface of the carrier core material is coated with resin by increasing the maximum peak-to-valley depth Rz of the particles, that is, by making the particle surface more uneven, a part of the carrier core material is exposed to the surface and the resin coating is caused. Although the electrical resistance of the carrier is reduced and the occurrence of development memory is suppressed to some extent, there is a possibility that the amount of developer pumped up to the development roller and the amount of developer conveyed to the development area are insufficient. In addition, if the carrier core material is extremely irregularly shaped, the particles of the carrier will be more likely to catch each other, and as a result, the magnetic brush formed on the surface of the developing roller will become hard, and there is a risk that the surface of the photoconductor may be damaged by the rubbing of the magnetic brush. .

本発明はこのような従来の問題に鑑みてなされたものであり、その目的は、現像メモリが抑制でき、また現像ローラへの現像剤のくみ上げ量及び現像領域への搬送量の低下が生じにくいキャリア芯材を提供することにある。 The present invention has been made in view of such conventional problems, and its purpose is to suppress development memory and prevent a decrease in the amount of developer pumped to the development roller and the amount of developer conveyed to the development area. Our objective is to provide carrier core materials.

また本発明の他の目的は、長期間の使用においても安定して良好な画質画像を形成することができる電子写真現像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 developing carrier and an electrophotographic developer that can stably form images of good quality even during long-term use.

前記目的を達成する本発明に係るフェライトキャリア芯材(以下、単に「キャリア芯材と記すことがある。」)は、細孔容積PV(cm/g)と残留磁化σ(Am/kg)との積PV×σから求められた値が0.008以上0.100以下の範囲であることを特徴とする。 The ferrite carrier core material (hereinafter sometimes simply referred to as "carrier core material") according to the present invention that achieves the above object has a pore volume PV (cm 3 /g) and a residual magnetization σ r (Am 2 / It is characterized in that the value obtained from the product PV×σ r of 0.008 to 0.100 is in the range of 0.008 to 0.100.

なお、本明細書における「フェライト」とは、通常、MFe(ただし、MはMn,Co,Ni,Cu,Zn,Mg,Ca,Srなど)の組成式で表され、スピネル型あるいは逆スピネル型の結晶構造をもつフェライトをいう。また、本明細書における細孔容積PV、残留磁化σ、粒子の最大山谷深さRzは後述の実施例に記載の測定方法によって測定される値である。 In addition, "ferrite" in this specification is usually represented by the composition formula of MFe 2 O 4 (however, M is Mn, Co, Ni, Cu, Zn, Mg, Ca, Sr, etc.), and is spinel type or A ferrite with an inverted spinel crystal structure. Further, in this specification, the pore volume PV, residual magnetization σ r , and maximum peak-to-valley depth Rz of the particles are values measured by a measuring method described in Examples described later.

ここで、前記構成のキャリア芯材において、(MnMg)Fe3-(x+y)(但し、0.1<x≦1,0.1<y≦1である。)で表される組成を有し、Mn,Mg,Feの総mol数に対してCaが0.10mol%超1.0mol%未満の範囲含有されているのが好ましい。 Here, in the carrier core material having the above configuration, it is expressed as (Mn x Mg y )Fe 3-(x+y) O 4 (0.1<x≦1, 0.1<y≦1). It is preferable that Ca be contained in a range of more than 0.10 mol% and less than 1.0 mol% based on the total mol number of Mn, Mg, and Fe.

前記構成のキャリア芯材において、粒子の最大山谷深さRzが1.4μm以上3.0μm以下であるのが好ましい。 In the carrier core material having the above configuration, it is preferable that the maximum peak-to-valley depth Rz of the particles is 1.4 μm or more and 3.0 μm or less.

また本発明によれば、前記のいずれかに記載のキャリア芯材の表面が樹脂で被覆されている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。 Further, according to the present invention, there is provided a carrier for electrophotographic development, characterized in that the surface of the carrier core material described above is coated with a resin.

そして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。 Further, according to the present invention, there is provided an electrophotographic developer characterized by containing the above-described carrier for electrophotographic development and a toner.

なお、本明細書において示す「~」は、特に断りのない限り、その前後に記載の数値を下限値及び上限値として含む意味で使用する。 In addition, unless otherwise specified, "~" shown in this specification is used in a meaning that includes the numerical values described before and after it as a lower limit value and an upper limit value.

本発明に係るキャリア芯材によれば、現像メモリが抑制されると共に、現像ローラへの現像剤のくみ上げ量及び現像領域への搬送量の低下が抑制される。 According to the carrier core material according to the present invention, development memory is suppressed, and a decrease in the amount of developer pumped to the developing roller and the amount conveyed to the development area is suppressed.

また本発明に係るキャリア芯材を含む現像剤を用いれば、長期間の使用においても安定して良好な画質画像を形成することができる。 Further, by using a developer containing the carrier core material according to the present invention, images of good quality can be stably formed even during long-term use.

本発明に係るキャリアを用いた現像装置の一例を示す概説図である。FIG. 1 is a schematic diagram showing an example of a developing device using a carrier according to the present invention.

本発明に係るキャリア芯材の大きな特徴は、細孔容積PV(cm/g)と残留磁化σ(Am/kg)との積PV×σが0.008以上0.100以下の範囲であることにある。PV×σから求められた値がこのような範囲にあることによってキャリア芯材の単位質量あたりの体積が大きくなると共にキャリア芯材の磁気的凝集も相まって、本発明に係るキャリア芯材を含む現像剤の現像ローラへのくみ上げ量が増加する。ここで、単位質量当たりの体積を増やしたいため細孔容積PVは大きくしたいが、大きくしすぎると1粒子当たりの残留磁化が弱くなり磁気的凝集が弱まるため細孔容積PVと残留磁化σのバランスが重要となる。細孔容積PV(cm/g)と残留磁化σ(Am/kg)との積PV×σが0.008未満であると、現像ローラにおける現像剤の搬送量の低下が生じやすくなる。一方、積PV×σが0.100を超えると、現像ローラからのキャリアの剥離が難しくなり、トナー付着量の少ないキャリアが再び現像領域に搬送されるおそれがある。好ましい積PV×σの範囲は0.050以上0.065以下の範囲である。 A major feature of the carrier core material according to the present invention is that the product PV×σ r of pore volume PV (cm 3 /g) and residual magnetization σ r (Am 2 /kg) is 0.008 or more and 0.100 or less. It lies in the range. When the value obtained from PV x σ r is in such a range, the volume per unit mass of the carrier core material becomes large, and the magnetic agglomeration of the carrier core material also occurs, which results in a carrier core material containing the carrier core material according to the present invention. The amount of developer pumped to the developing roller increases. Here, we want to increase the volume per unit mass, so we want to increase the pore volume PV, but if it is made too large, the residual magnetization per particle will weaken and the magnetic aggregation will weaken, so the pore volume PV and residual magnetization σ r Balance is key. If the product PV×σ r of pore volume PV (cm 3 /g) and residual magnetization σ r (Am 2 /kg) is less than 0.008, the amount of developer conveyed by the developing roller is likely to decrease. Become. On the other hand, when the product PV x σ r exceeds 0.100, it becomes difficult to peel the carrier from the developing roller, and there is a possibility that the carrier with a small amount of toner adhesion is conveyed to the developing area again. A preferable range of the product PV×σ r is from 0.050 to 0.065.

本発明に係るキャリア芯材の細孔容積PV(cm/g)の好ましい範囲は0.002以上0.100以下の範囲であり、より好ましい範囲は0.008以上0.040以下の範囲である。細孔容積PVが小さすぎると現像ローラへの現像剤のくみ上げ量が低下するおそれがある一方、細孔容積PVが大きすぎるとキャリア芯材の1粒子当たりの磁化が低下してキャリア付着などの新たな不具合が発生するおそれがある。 The pore volume PV (cm 3 /g) of the carrier core material according to the present invention is preferably in the range of 0.002 or more and 0.100 or less, and more preferably in the range of 0.008 or more and 0.040 or less. be. If the pore volume PV is too small, there is a risk that the amount of developer pumped to the developing roller will decrease, while if the pore volume PV is too large, the magnetization per particle of the carrier core material will decrease, causing problems such as carrier adhesion. New problems may occur.

また、残留磁化σ(Am/kg)の好ましい範囲は0.1以上5.0の範囲であり、より好ましい範囲は0.7以上2.5以下の範囲である。残留磁化σが小さすぎると現像ローラへの現像剤のくみ上げ量が低下するおそれがある一方、残留磁化σが大きすぎると現像ローラからのキャリアの剥離が困難になるおそれがある。 Further, the preferable range of residual magnetization σ r (Am 2 /kg) is 0.1 or more and 5.0, and the more preferable range is 0.7 or more and 2.5 or less. If the residual magnetization σ r is too small, the amount of developer pumped to the developing roller may decrease, while if the residual magnetization σ r is too large, it may be difficult to separate the carrier from the developing roller.

本発明に係るキャリア芯材において、粒子の最大山谷深さRzの好ましい範囲は、1.4μm以上3.0μm以下の範囲である。最大山谷深さRzがこの範囲であることによって画像メモリやキャリア付着が抑制されやすくなる。粒子の最大山谷深さRzのより好ましい範囲は1.4μm以上2.1μm以下の範囲である。 In the carrier core material according to the present invention, the maximum peak-to-valley depth Rz of the particles is preferably in the range of 1.4 μm or more and 3.0 μm or less. When the maximum peak-to-valley depth Rz is within this range, image memory and carrier adhesion can be easily suppressed. A more preferable range of the maximum peak-to-valley depth Rz of the particles is 1.4 μm or more and 2.1 μm or less.

また本発明では、見掛け密度AD(g/cm)は1.80以上2.80以下の範囲が好ましく、より好ましくは2.00以上2.50以下の範囲である。 Further, in the present invention, the apparent density AD (g/cm 3 ) is preferably in the range of 1.80 or more and 2.80 or less, more preferably in the range of 2.00 or more and 2.50 or less.

また、流動度FR(sec/50g)は20以上50以下の範囲が好ましく、より好ましくは24以上40以下の範囲である。流動度FRがこの範囲であるとキャリア芯材を構成する粒子間のストレスが小さく樹脂被覆層の摩耗が抑制される。 Further, the fluidity FR (sec/50g) is preferably in the range of 20 or more and 50 or less, more preferably in the range of 24 or more and 40 or less. When the fluidity FR is within this range, the stress between particles constituting the carrier core material is small, and wear of the resin coating layer is suppressed.

本発明のキャリア芯材の体積平均粒径(D50)としては、20μm以上60μm以下の範囲が好ましく、より好ましくは25μm以上40μm以下の範囲である。また、キャリア芯材の粒径22μm以下の割合は5.0%以下が好ましく、より好ましくは1.5%以下である。 The volume average particle diameter (D 50 ) of the carrier core material of the present invention is preferably in the range of 20 μm or more and 60 μm or less, more preferably in the range of 25 μm or more and 40 μm or less. Further, the proportion of the carrier core material having a particle size of 22 μm or less is preferably 5.0% or less, more preferably 1.5% or less.

本発明のキャリア芯材の磁気特性は次の範囲が好ましい。飽和磁化σ(Am/kg)は40以上90以下の範囲が好ましく、より好ましくは55以上70以下の範囲である。また、磁場79.58×10A/m(1,000エルステッド)を印加した際の磁化σ1k(Am/kg)は30以上80以下の範囲が好ましく、より好ましくは45以上65以下の範囲である。そしてまた、保持力H(×10/(4π)A/m)は1.0以上25.0以下の範囲が好ましく、より好ましくは8.0以上20以下の範囲である。 The magnetic properties of the carrier core material of the present invention are preferably in the following range. The saturation magnetization σ s (Am 2 /kg) is preferably in the range of 40 or more and 90 or less, more preferably in the range of 55 or more and 70 or less. Furthermore, the magnetization σ 1k (Am 2 /kg) when a magnetic field of 79.58×10 3 A/m (1,000 Oe) is applied is preferably in the range of 30 to 80, more preferably in the range of 45 to 65. range. Further, the holding force H c (×10 3 /(4π) A/m) is preferably in the range of 1.0 or more and 25.0 or less, more preferably 8.0 or more and 20 or less.

本発明のキャリア芯材の形状特性は次の範囲が好ましい。平均長さRSm(μm)は4.0以上10.0以下の範囲が好ましく、より好ましくは5.0以上8.0以下の範囲である。また、キャリア芯材の歪度Rskは-0.50以上0.00以下の範囲が好ましく、より好ましくは-0.40以上-0.05以下の範囲である。 The shape characteristics of the carrier core material of the present invention are preferably in the following ranges. The average length RSm (μm) is preferably in the range of 4.0 or more and 10.0 or less, more preferably in the range of 5.0 or more and 8.0 or less. Further, the skewness Rsk of the carrier core material is preferably in the range of -0.50 or more and 0.00 or less, more preferably in the range of -0.40 or more and -0.05 or less.

本発明のキャリア芯材のBET比表面積(m/g)は0.03以上0.50以下の範囲が好ましく、より好ましくは0.04以上0.30以下の範囲である。本発明のキャリア芯材の真密度(g/cm)は4.2以上5.2以下の範囲が好ましく、より好ましくは4.5以上4.9以下の範囲である。 The BET specific surface area (m 2 /g) of the carrier core material of the present invention is preferably in the range of 0.03 or more and 0.50 or less, more preferably in the range of 0.04 or more and 0.30 or less. The true density (g/cm 3 ) of the carrier core material of the present invention is preferably in the range of 4.2 or more and 5.2 or less, more preferably in the range of 4.5 or more and 4.9 or less.

本発明のキャリア芯材の絶縁破壊電圧BD(V)は1000以上が好ましく、より好ましくは1200以上である。 The dielectric breakdown voltage BD (V) of the carrier core material of the present invention is preferably 1000 or more, more preferably 1200 or more.

本発明に係るキャリア芯材は、(MnMg)Fe3-(x+y)(但し、0.1<x≦1,0.1<y≦1である。)で表される組成を有し、Mn,Mg,Feの総mol数に対してCaが0.10mol%超1.0mol%未満の範囲含有されているのが好ましい。Caが上記量含有されることによって所望の電気特性、磁気特性、形状特性を得ることができる。 The carrier core material according to the present invention has a composition represented by (Mn x Mg y )Fe 3-(x+y) O 4 (0.1<x≦1, 0.1<y≦1). It is preferable that Ca is contained in a range of more than 0.10 mol% and less than 1.0 mol% with respect to the total mol number of Mn, Mg, and Fe. By containing Ca in the above amount, desired electrical properties, magnetic properties, and shape properties can be obtained.

本発明のキャリア芯材の製造方法に特に限定はないが、以下に説明する製造方法が好適である。 Although there is no particular limitation on the method for manufacturing the carrier core material of the present invention, the manufacturing method described below is suitable.

まず、Fe成分原料、Mn成分原料、Mg成分原料、Ca成分原料、そして必要により従来公知の添加剤を秤量する。Fe成分原料としては、Fe等が好適に使用される。Mn成分原料としてはMnCO、Mn等が使用できる。Mg成分原料としてはMgCO、Mg等が使用できる。また、Ca成分原料としては、CaCO、Ca(NO等が好適に使用できる。 First, Fe component raw material, Mn component raw material, Mg component raw material, Ca component raw material, and if necessary, conventionally known additives are weighed. As the Fe component raw material, Fe 2 O 3 and the like are preferably used. MnCO 3 , Mn 3 O 4 and the like can be used as the Mn component raw material. MgCO 3 , Mg 3 O 4 and the like can be used as raw materials for the Mg component. Further, as the Ca component raw material, CaCO 3 , Ca(NO 3 ) 2, etc. can be suitably used.

次いで、原料を分散媒中に投入しスラリーを作製する。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、前記仮焼成原料の他、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0.1質量%~2質量%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やメタクリル酸系ポリマー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0.1質量%~2質量%程度とするのが好ましい。その他、カーボンブラックなどの還元剤、アンモニアなどのpH調整剤、潤滑剤、焼結促進剤等を配合してもよい。スラリーの固形分濃度は50質量%~90質量%の範囲が望ましい。より好ましくは60質量%~80質量%である。60質量%以上であれば、造粒物中に粒子内細孔が少なく、焼成時の焼結不足を防ぐことができる。 Next, the raw materials are introduced into a dispersion medium to prepare a slurry. Water is suitable as the dispersion medium used in the present invention. The dispersion medium may contain a binder, a dispersant, etc., if necessary, in addition to the above-mentioned calcined raw materials. As the binder, for example, polyvinyl alcohol can be suitably used. The amount of binder to be blended is preferably such that the concentration in the slurry is approximately 0.1% by mass to 2% by mass. Further, as the dispersant, for example, ammonium polycarboxylate, methacrylic acid polymer, etc. can be suitably used. The amount of the dispersant to be blended is preferably such that the concentration in the slurry is approximately 0.1% by mass to 2% by mass. In addition, a reducing agent such as carbon black, a pH adjuster such as ammonia, a lubricant, a sintering accelerator, etc. may be added. The solid content concentration of the slurry is preferably in the range of 50% by mass to 90% by mass. More preferably, it is 60% by mass to 80% by mass. When it is 60% by mass or more, there are few intraparticle pores in the granules, and insufficient sintering during firing can be prevented.

なお、秤量した原料を混合し仮焼成し解粒した後、分散媒に投入しスラリーを作製してもよい。仮焼成の温度としては750℃~1000℃の範囲が好ましい。750℃以上であれば、仮焼による一部フェライト化が進み、焼成時のガス発生量が少なく、固体間反応が十分に進むため、好ましい。一方、1000℃以下であれば、仮焼による焼結が弱く、後のスラリー粉砕工程で原料を十分に粉砕できるので好ましい。また、仮焼成時の雰囲気としては大気雰囲気が好ましい。 Note that the weighed raw materials may be mixed, pre-calcined and granulated, and then added to a dispersion medium to produce a slurry. The temperature for pre-firing is preferably in the range of 750°C to 1000°C. If it is 750° C. or higher, partial ferrite formation during calcination progresses, the amount of gas generated during calcination is small, and solid-solid reactions proceed sufficiently, which is preferable. On the other hand, if the temperature is 1000° C. or lower, sintering due to calcination is weak and the raw material can be sufficiently pulverized in the subsequent slurry pulverization step, which is preferable. Furthermore, an atmospheric atmosphere is preferable as the atmosphere during the temporary firing.

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 pulverization is performed for a predetermined period of time using a ball mill or a vibration mill. The average particle size of the raw material after pulverization is preferably 5 μm or less, more preferably 1 μm or less. It is preferable that a vibration mill or a ball mill contain media of a predetermined particle size. Examples of media materials include iron-based chromium steel and oxide-based zirconia, titania, and alumina. The form of the pulverization process may be either continuous or batch. The particle size of the pulverized material is adjusted by the pulverization time, rotation speed, material and particle size of the media used, etc.

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形に造粒する。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10μm~200μmの球形の造粒物が得られる。次いで、必要により、得られた造粒物を振動篩を用いて分級し所定の粒径範囲の造粒物を作製する。 The pulverized slurry is then spray dried and granulated. Specifically, the slurry is introduced into a spray dryer such as a spray dryer, and is sprayed into the atmosphere to form spherical granules. The atmospheric temperature during spray drying is preferably in the range of 100°C to 300°C. As a result, spherical granules with a particle size of 10 μm to 200 μm are obtained. Next, if necessary, the obtained granules are classified using a vibrating sieve to produce granules having a predetermined particle size range.

次に、前記の造粒物を所定温度に加熱した炉に投入して、フェライト粒子を合成するための一般的な手法で焼成することにより、フェライト粒子を生成させる。焼成温度としては1050℃~1350℃の範囲が好ましい。より好ましくは1100℃~1200℃の範囲である。焼成温度が1050℃以下であると、相変態が起こりにくくなるとともに焼結も進みにくくなる。また、焼成温度が1350℃を超えると、過剰焼結による過大グレインの発生がするおそれがある。前記焼成温度に至るまでの昇温速度としては250℃/h~500℃/hの範囲が好ましい。焼成温度での保持時間は2時間以上が好ましい。フェライト粒子表面の凹凸は焼成工程における酸素濃度によっても調整可能である。具体的には酸素濃度を0.05%~10%とする。また、冷却時の酸素濃度を焼成時の酸素濃度よりも低くすることによって、フェライト相の酸化状態の調整を図ってもよい。具体的には酸素濃度を0.05%~1.5%の範囲とする。昇温・焼結・冷却における酸素濃度は0.05%~10%の範囲に制御するのが好ましい。より好ましい昇温段階での酸素濃度は0.6%~5%の範囲である。 Next, the granulated material is placed in a furnace heated to a predetermined temperature and fired using a common method for synthesizing ferrite particles, thereby producing ferrite particles. The firing temperature is preferably in the range of 1050°C to 1350°C. More preferably, the temperature is in the range of 1100°C to 1200°C. When the firing temperature is 1050° C. or lower, phase transformation is less likely to occur and sintering is also less likely to proceed. Furthermore, if the firing temperature exceeds 1350° C., excessive sintering may result in generation of excessive grains. The rate of temperature increase up to the firing temperature is preferably in the range of 250°C/h to 500°C/h. The holding time at the firing temperature is preferably 2 hours or more. The unevenness on the surface of the ferrite particles can also be adjusted by adjusting the oxygen concentration during the firing process. Specifically, the oxygen concentration is set to 0.05% to 10%. Furthermore, the oxidation state of the ferrite phase may be adjusted by lowering the oxygen concentration during cooling than the oxygen concentration during firing. Specifically, the oxygen concentration is set in the range of 0.05% to 1.5%. The oxygen concentration during heating, sintering, and cooling is preferably controlled within the range of 0.05% to 10%. More preferably, the oxygen concentration during the heating stage is in the range of 0.6% to 5%.

このようにして得られた焼成物を必要により解粒する。具体的には、例えば、ハンマーミル等によって焼成物を解粒する。解粒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。また解粒処理後、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。フェライト粒子の粒径としては25μm以上50μm未満が好ましい。 The fired product thus obtained is granulated if necessary. Specifically, the fired product is pulverized using, for example, a hammer mill. The form of the granulation process may be either continuous or batch. Further, after the disintegration treatment, classification may be performed, if necessary, in order to align the particle size within a predetermined range. As the classification method, conventionally known methods such as wind classification and sieve classification can be used. Further, after primary classification using an air classifier, the particle size may be adjusted to a predetermined range using a vibrating sieve or an ultrasonic sieve. Furthermore, after the classification step, non-magnetic particles may be removed using a magnetic field separator. The particle size of the ferrite particles is preferably 25 μm or more and less than 50 μm.

その後、必要に応じて、分級後のフェライト粒子を酸化性雰囲気中で加熱して、粒子表面に酸化被膜を形成してフェライト粒子の高抵抗化を図ってもよい(高抵抗化処理)。酸化性雰囲気としては大気雰囲気又は酸素と窒素の混合雰囲気のいずれでもよい。また、加熱温度は200℃以上800℃以下の範囲が好ましく、360℃以上550℃以下の範囲がさらに好ましい。加熱時間は0.5時間以上5時間以下の範囲が好ましい。なお、フェライト粒子の表面と内部とを均質化する観点からは加熱温度は低温であるのが望ましい。 Thereafter, if necessary, the classified ferrite particles may be heated in an oxidizing atmosphere to form an oxide film on the particle surface to increase the resistance of the ferrite particles (high resistance treatment). The oxidizing atmosphere may be an air atmosphere or a mixed atmosphere of oxygen and nitrogen. Further, the heating temperature is preferably in the range of 200°C or more and 800°C or less, and more preferably in the range of 360°C or more and 550°C or less. The heating time is preferably in the range of 0.5 hours or more and 5 hours or less. Note that, from the viewpoint of homogenizing the surface and interior of the ferrite particles, it is desirable that the heating temperature is low.

以上のようにして作製したフェライト粒子を本発明のキャリア芯材として用いる。そして、所望の帯電性等を得るために、キャリア芯材の外周を樹脂で被覆して電子写真現像用キャリアとする。 The ferrite particles produced as described above are used as the carrier core material of the present invention. Then, in order to obtain desired chargeability, etc., the outer periphery of the carrier core material is coated with a resin to obtain a carrier for electrophotographic development.

キャリア芯材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 to coat the surface of the carrier core material, such as polyethylene, polypropylene, polyvinyl chloride, poly-4-methylpentene-1, polyvinylidene chloride, ABS (acrylonitrile-butadiene-styrene), etc. ) resins, polystyrene, (meth)acrylic resins, polyvinyl alcohol resins, thermoplastic elastomers such as polyvinyl chloride, polyurethane, polyester, polyamide, and polybutadiene, and fluorosilicone resins.

キャリア芯材の表面を樹脂で被覆するには、樹脂の溶液又は分散液をキャリア芯材に施せばよい。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質量%以上30質量%以下、特に0.001質量%以上2質量%以下の範囲内にあるのがよい。 In order to coat the surface of the carrier core material with a resin, a resin solution or dispersion may be applied to the carrier core material. Solvents for coating solutions 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. One or more of alcoholic solvents such as; cellosolve solvents such as ethyl cellosolve and butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate; and amide solvents such as dimethylformamide and dimethylacetamide can be used. . The concentration of the resin component in the coating solution is generally in the range of 0.001% by mass to 30% by mass, particularly 0.001% by mass to 2% by mass.

キャリア芯材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 for coating the carrier core material with the resin, for example, a spray drying method, a fluidized bed method, a spray drying method using a fluidized bed, a dipping method, etc. can be used. Among these, the fluidized bed method is particularly preferred since it allows efficient coating with a small amount of resin. For example, in the case of a fluidized bed method, the amount of resin coating can be adjusted by adjusting the amount of resin solution sprayed and the spraying time.

キャリアの粒子径は、一般に、体積平均粒子径で20μm以上60μm未満の範囲、特に25μm以上40μm以下の範囲が好ましい。 The particle size of the carrier is generally preferably in the range of 20 μm or more and less than 60 μm, particularly in the range of 25 μm or more and 40 μm or less in volume average particle size.

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キャリアとトナーとを混合してなる。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1質量%以上15質量%以下の範囲が好ましい。トナー濃度が1質量%未満の場合、画像濃度が薄くなりすぎ、他方トナー濃度が15質量%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質量%以上10質量%以下の範囲である。 The electrophotographic developer according to the present invention is made by mixing the carrier prepared as described above and a toner. The mixing ratio of carrier and toner is not particularly limited, and may be appropriately determined based on the developing conditions of the developing device used. Generally, the toner concentration in the developer is preferably in the range of 1% by mass or more and 15% by mass or less. If the toner concentration is less than 1% by mass, the image density becomes too thin, while if the toner concentration exceeds 15% by mass, toner scatters in the developing device and toner adheres to dirt inside the machine or to the background parts such as transfer paper. This is because there is a risk that problems may occur. A more preferable toner concentration is in the range of 3% by mass or more and 10% by mass or less.

トナーとしては、重合法、粉砕分級法、溶融造粒法、スプレー造粒法など従来公知の方法で製造したものが使用できる。具体的には、熱可塑性樹脂を主成分とする結着樹脂中に、着色剤、離型剤、帯電制御剤等を含有させたものが好適に使用できる。 As the toner, those manufactured by conventionally known methods such as polymerization method, crushing classification method, melt granulation method, spray granulation method, etc. can be used. Specifically, a binder resin whose main component is a thermoplastic resin containing a coloring agent, a mold release agent, a charge control agent, etc. can be suitably used.

トナーの粒径は、一般に、コールターカウンターによる体積平均粒径で5μm以上15μm以下の範囲が好ましく、7μm以上12μm以下の範囲がより好ましい。 Generally, the particle size of the toner is preferably in the range of 5 μm or more and 15 μm or less, more preferably 7 μm or more and 12 μm or less, as measured by a Coulter Counter volume average particle size.

トナー表面には、必要により、改質剤を添加してもよい。改質剤としては、例えば、シリカ、アルミナ、酸化亜鉛、酸化チタン、酸化マグネシウム、ポリメチルメタクリレート等が挙げられる。これらの1種又は2種以上を組み合わせて使用できる。 A modifier may be added to the toner surface if necessary. Examples of the modifier include silica, alumina, zinc oxide, titanium oxide, magnesium oxide, and polymethyl methacrylate. These can be used alone or in combination of two or more.

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。 A conventionally known mixing device can be used to mix the carrier and toner. For example, a Henschel mixer, a V-type mixer, a tumbler mixer, a hybridizer, etc. can be used.

本発明の現像剤を用いた現像方法に特に限定はないが、磁気ブラシ現像法が好適である。図1に、磁気ブラシ現像を行う現像装置の一例を示す概説図を示す。図1に示す現像装置は、複数の磁極を内蔵した回転自在の現像ローラ3と、現像部へ搬送される現像ローラ3上の現像剤量を規制する規制ブレード6と、水平方向に平行に配置され、互いに逆向きに現像剤を撹拌搬送する2本のスクリュー1,2と、2本のスクリュー1,2の間に形成され、両スクリューの両端部において、一方のスクリューから他方のスクリューに現像剤の移動を可能とし、両端部以外での現像剤の移動を防ぐ仕切板4とを備える。 Although there are no particular limitations on the developing method using the developer of the present invention, a magnetic brush developing method is suitable. FIG. 1 is a schematic diagram showing an example of a developing device that performs magnetic brush development. The developing device shown in FIG. 1 includes a rotatable developing roller 3 that includes a plurality of magnetic poles, and a regulating blade 6 that regulates the amount of developer on the developing roller 3 that is conveyed to the developing section, which are arranged in parallel in the horizontal direction. It is formed between two screws 1 and 2 that agitate and convey the developer in opposite directions, and the developer is transferred from one screw to the other at both ends of both screws. The developer is provided with a partition plate 4 that allows the developer to move and prevents the developer from moving at areas other than both ends.

2本のスクリュー1,2は、螺旋状の羽根13,23が同じ傾斜角で軸部11,21に形成されたものであって、不図示の駆動機構によって同方向に回転し、現像剤を互いに逆方向に搬送する。そして、スクリュー1,2の両端部において一方のスクリューから他方のスクリューに現像剤が移動する。これによりトナーとキャリアからなる現像剤は装置内を常に循環し撹拌されることになる。 The two screws 1 and 2 have spiral blades 13 and 23 formed on the shaft portions 11 and 21 at the same inclination angle, and are rotated in the same direction by a drive mechanism (not shown) to remove the developer. Convey in opposite directions. Then, the developer moves from one screw to the other screw at both ends of the screws 1 and 2. As a result, the developer consisting of toner and carrier is constantly circulated and stirred within the device.

一方、現像ローラ3は、表面に数μmの凹凸を付けた金属製の筒状体の内部に、磁極発生手段として、現像磁極N、搬送磁極S、剥離磁極N、汲み上げ磁極N、ブレード磁極Sの5つの磁極を順に配置した固定磁石を有してなる。現像ローラ3の筒状体が矢印方向に回転すると、汲み上げ磁極Nの磁力によって、スクリュー1から現像ローラ3へ現像剤が汲み上げられる。現像ローラ3の表面に担持された現像剤は、規制ブレード6により層規制された後、現像領域へ搬送される。 On the other hand, the developing roller 3 has a developing magnetic pole N 1 , a conveying magnetic pole S 1 , a peeling magnetic pole N 2 , and a pumping magnetic pole N 3 as magnetic pole generating means inside a metal cylindrical body with irregularities of several μm on the surface. , a fixed magnet in which five magnetic poles of blade magnetic pole S2 are arranged in sequence. When the cylindrical body of the developing roller 3 rotates in the direction of the arrow, the developer is pumped up from the screw 1 to the developing roller 3 by the magnetic force of the pumping magnetic pole N3 . The developer carried on the surface of the developing roller 3 is layer-regulated by the regulating blade 6 and then conveyed to the developing area.

現像領域では、直流電圧に交流電圧を重畳したバイアス電圧が転写電圧電源8から現像ローラ3に印加される。バイアス電圧の直流電圧成分は、感光体ドラム5表面の背景部電位と画像部電位との間の電位とされる。また、背景部電位と画像部電位とは、バイアス電圧の最大値と最小値との間の電位とされる。バイアス電圧のピーク間電圧は0.5kV~5kVの範囲が好ましく、周波数は1kHz~10kHzの範囲が好ましい。またバイアス電圧の波形は矩形波、サイン波、三角波などいずれであってもよい。これによって、現像領域においてトナー及びキャリアが振動し、トナーが感光体ドラム5上の静電潜像に付着して現像がなされる。 In the developing region, a bias voltage obtained by superimposing an alternating current voltage on a direct current voltage is applied to the developing roller 3 from a transfer voltage power source 8 . The DC voltage component of the bias voltage has a potential between the background potential and the image potential on the surface of the photosensitive drum 5. Further, the background potential and the image potential are potentials between the maximum value and the minimum value of the bias voltage. The peak-to-peak voltage of the bias voltage is preferably in the range of 0.5 kV to 5 kV, and the frequency is preferably in the range of 1 kHz to 10 kHz. Further, the waveform of the bias voltage may be any one such as a rectangular wave, a sine wave, or a triangular wave. As a result, the toner and carrier vibrate in the development area, and the toner adheres to the electrostatic latent image on the photoreceptor drum 5 to perform development.

その後現像ローラ3上の現像剤は、搬送磁極Sによって装置内部に搬送され、剥離電極Nによって現像ローラ3から剥離して、スクリュー1,2によって装置内を再び循環搬送され、現像に供していない現像剤と混合撹拌される。そして汲み上げ極Nによって、新たに現像剤がスクリュー1から現像ローラ3へ供給される。 Thereafter, the developer on the developing roller 3 is transported into the apparatus by the transport magnetic pole S1 , peeled off from the developing roller 3 by the peeling electrode N2 , and circulated again within the apparatus by the screws 1 and 2 to be used for development. It is not mixed with developer and stirred. Then, developer is newly supplied from the screw 1 to the developing roller 3 by the pumping pole N3 .

なお、図1に示した実施形態では現像ローラ3に内蔵された磁極は5つであったが、現像剤の現像領域での移動量を一層大きくしたり、汲み上げ性等を一層向上させるために、磁極を8極や10極、12極と増やしてももちろん構わない。 In the embodiment shown in FIG. 1, the number of magnetic poles built into the developing roller 3 is five, but in order to further increase the amount of movement of the developer in the developing area and to further improve pumping performance, etc. Of course, the number of magnetic poles may be increased to 8, 10, or 12.

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, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples in any way.

参考例1
原料として、Fe(平均粒径:0.6μm)14.34kg、Mn(平均粒径:2μm)4.62kg、MgO 1.04kgを混合した。この混合物をローラーコンパクターでペレット化した。得られたペレットを大気雰囲気の条件下、850℃にてロータリー式の焼成炉で仮焼成を行った。乾式ビーズミルで6時間粉砕し、仮焼原料を得た。得られた仮焼成粉を水7.12kg中に分散し、CaCOを149.5g、メタクリル酸系ポリマー21%含有水溶液を219.7g添加し、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。このスラリーにおける固形分濃度は73.5%、スラリー中の原料の累積分布50%粒径D50は1.5μm、累積分布90%粒径D90は5.3μmであった。
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、乾燥造粒粉を得た。なお、このとき、目的の粒度分布以外の造粒粉は篩により除去した。
この造粒粉を、電気焼成炉に投入し、温度1160℃で保持時間3時間として、本焼成を行った。その後酸素濃度0.75%で6時間かけて冷却した。得られた焼成物は解粒後に篩を用いて分級し、平均粒径34.8μm、粒径22μm以下の割合が0.9%のキャリア芯材を得た。
得られたキャリア芯材の見掛け密度、流動度、体積平均粒径(平均粒径)、磁気特性、細孔容積、BET比表面積、静的電気抵抗、真密度を下記に示す方法で測定した。測定結果を表1及び表2に示す。なお、以下の実施例及び比較例のキャリア芯材についても同様の方法で物性測定した。
Reference example 1
As raw materials, 14.34 kg of Fe 2 O 3 (average particle size: 0.6 μm), 4.62 kg of Mn 3 O 4 (average particle size: 2 μm), and 1.04 kg of MgO were mixed. This mixture was pelletized using a roller compactor. The obtained pellets were pre-calcined in a rotary kiln at 850° C. under atmospheric conditions. The mixture was ground in a dry bead mill for 6 hours to obtain a calcined raw material. The obtained calcined powder was dispersed in 7.12 kg of water, 149.5 g of CaCO 3 and 219.7 g of an aqueous solution containing 21% methacrylic acid polymer were added, and the mixture was pulverized using a wet ball mill (media diameter 2 mm). A mixed slurry was obtained. The solid content concentration in this slurry was 73.5%, the cumulative distribution 50% particle size D 50 of the raw materials in the slurry was 1.5 μm, and the cumulative distribution 90% particle size D 90 was 5.3 μm.
This mixed slurry was sprayed into hot air at about 130° C. using a spray dryer to obtain dry granulated powder. At this time, granulated powder other than the target particle size distribution was removed using a sieve.
This granulated powder was put into an electric firing furnace, and main firing was performed at a temperature of 1160° C. for a holding time of 3 hours. Thereafter, it was cooled for 6 hours at an oxygen concentration of 0.75%. The obtained fired product was cracked and then classified using a sieve to obtain a carrier core material having an average particle size of 34.8 μm and a proportion of 0.9% having a particle size of 22 μm or less.
The apparent density, fluidity, volume average particle size (average particle size), magnetic properties, pore volume, BET specific surface area, static electrical resistance, and true density of the obtained carrier core material were measured by the methods shown below. The measurement results are shown in Tables 1 and 2. The physical properties of the carrier core materials of the following Examples and Comparative Examples were also measured in the same manner.

参考例2
本焼成の温度を1140℃とした以外は参考例1と同様にして、平均粒径35.5μm、粒径22μm以下の割合が0.9%のキャリア芯材を得た。
Reference example 2
A carrier core material having an average particle size of 35.5 μm and a proportion of particles with a particle size of 22 μm or less at 0.9% was obtained in the same manner as in Reference Example 1 except that the main firing temperature was 1140° C.

参考例3
本焼成の温度を1120℃とした以外は参考例1と同様にして、平均粒径35.7μm、粒径22μm以下の割合が1.0%のキャリア芯材を得た。
Reference example 3
A carrier core material having an average particle size of 35.7 μm and a ratio of 1.0% having a particle size of 22 μm or less was obtained in the same manner as in Reference Example 1 except that the main firing temperature was 1120° C.

参考例4
本焼成の温度を1100℃とした以外は参考例1と同様にして、平均粒径36.2μm、粒径22μm以下の割合が0.9%のキャリア芯材を得た。
Reference example 4
A carrier core material having an average particle size of 36.2 μm and a proportion of particles with a particle size of 22 μm or less at 0.9% was obtained in the same manner as in Reference Example 1 except that the main firing temperature was 1100° C.

実施例5
参考例4で得られたキャリア芯材に対して、温度420℃、大気下で1時間保持することにより酸化処理を施し実施例5に係るキャリア芯材を得た。
Example 5
The carrier core material obtained in Reference Example 4 was subjected to oxidation treatment by holding it at a temperature of 420° C. in the atmosphere for 1 hour to obtain a carrier core material according to Example 5.

実施例6
参考例4で得られたキャリア芯材に対して、温度440℃、大気下で1時間保持することにより酸化処理を施し実施例6に係るキャリア芯材を得た。
Example 6
The carrier core material obtained in Reference Example 4 was subjected to oxidation treatment by holding it at a temperature of 440° C. in the atmosphere for 1 hour to obtain a carrier core material according to Example 6.

実施例7
参考例4で得られたキャリア芯材に対して、温度460℃、大気下で1時間保持することにより酸化処理を施し実施例7に係るキャリア芯材を得た。
Example 7
The carrier core material obtained in Reference Example 4 was subjected to oxidation treatment by holding it at a temperature of 460° C. in the atmosphere for 1 hour to obtain a carrier core material according to Example 7.

実施例8
参考例4で得られたキャリア芯材に対して、温度480℃、大気下で1時間保持することにより酸化処理を施し実施例8に係るキャリア芯材を得た。
Example 8
The carrier core material obtained in Reference Example 4 was subjected to oxidation treatment by holding it at a temperature of 480° C. in the atmosphere for 1 hour to obtain a carrier core material according to Example 8.

比較例1
原料として、Fe(平均粒径:0.6μm)7.36kg、MgOを1.69kgを混合した。この混合物をローラーコンパクターでペレット化した。得られたペレットを大気雰囲気の条件下、970℃にてロータリー式の焼成炉で仮焼成を行った。乾式ビーズミルで6時間粉砕し、仮焼原料を得た。得られた仮焼成粉を水11.50kg中に分散し、Fe(平均粒径:0.6μm)16.85kg、Mn(平均粒径:3.4μm)8.05kg、CaCOを255.2g、メタクリル酸系ポリマー21%含有水溶液を271.7g、pH調整剤としてアンモニア水を69.2g、還元剤としてカーボンブラックを101.9g添加し、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。このスラリーにおける固形分濃度は73.5%、スラリー中原料粒径D50は0.9μm、D90は3.2μmであった。
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、乾燥造粒粉を得た。なお、このとき、目的の粒度分布以外の造粒粉は篩により除去した。
この造粒粉を、電気焼成炉に投入し、温度1300℃で保持時間3時間として、本焼成を行った。その後酸素濃度0.4%で6時間かけて冷却した。得られた焼成物は解粒後に篩を用いて分級し、平均粒径35.2μm、粒径22μm以下の割合が1.0%のキャリア芯材を得た。
Comparative example 1
As raw materials, 7.36 kg of Fe 2 O 3 (average particle size: 0.6 μm) and 1.69 kg of MgO were mixed. This mixture was pelletized using a roller compactor. The obtained pellets were pre-calcined in a rotary kiln at 970° C. under atmospheric conditions. The mixture was ground in a dry bead mill for 6 hours to obtain a calcined raw material. The obtained calcined powder was dispersed in 11.50 kg of water, and 16.85 kg of Fe 2 O 3 (average particle size: 0.6 μm), 8.05 kg of Mn 3 O 4 (average particle size: 3.4 μm), Added 255.2 g of CaCO 3 , 271.7 g of an aqueous solution containing 21% methacrylic acid polymer, 69.2 g of ammonia water as a pH adjuster, and 101.9 g of carbon black as a reducing agent, and wet ball mill (media diameter 2 mm). The mixture was pulverized to obtain a mixed slurry. The solid content concentration in this slurry was 73.5%, the raw material particle size D50 in the slurry was 0.9 μm, and the D90 was 3.2 μm.
This mixed slurry was sprayed into hot air at about 130° C. using a spray dryer to obtain dry granulated powder. At this time, granulated powder other than the target particle size distribution was removed using a sieve.
This granulated powder was put into an electric firing furnace, and main firing was performed at a temperature of 1300° C. for a holding time of 3 hours. Thereafter, it was cooled over 6 hours at an oxygen concentration of 0.4%. The obtained fired product was cracked and then classified using a sieve to obtain a carrier core material having an average particle size of 35.2 μm and a proportion of 1.0% having a particle size of 22 μm or less.

比較例2
本焼成の温度を1250℃とした以外は参考例1と同様にして、平均粒径35.6μm、粒径22μm以下の割合が1.0%のキャリア芯材を得た。
Comparative example 2
A carrier core material having an average particle size of 35.6 μm and a proportion of particles with a particle size of 22 μm or less at 1.0% was obtained in the same manner as in Reference Example 1 except that the main firing temperature was 1250° C.

比較例3
本焼成の温度を1250℃で保持時間4.5時間とし、その後酸素濃度0.75%で9時間かけて冷却した以外は参考例1と同様にして、平均粒径35.2μm、粒径22μm以下の割合が1.2%のキャリア芯材を得た。
Comparative example 3
The average particle size was 35.2 μm and the particle size was 22 μm. A carrier core material having the following ratio of 1.2% was obtained.

比較例4
比較例3と同様にして、平均粒径39.4μm、粒径22μm以下の割合が1.4%のキャリア芯材を得た。
Comparative example 4
In the same manner as in Comparative Example 3, a carrier core material having an average particle size of 39.4 μm and a proportion of 1.4% having a particle size of 22 μm or less was obtained.

比較例5
比較例3と同様にして、平均粒径44.0μm、粒径22μm以下の割合が0.3%のキャリア芯材を得た。
Comparative example 5
In the same manner as Comparative Example 3, a carrier core material having an average particle size of 44.0 μm and a proportion of particles having a particle size of 22 μm or less at 0.3% was obtained.

比較例6
比較例3で得られたキャリア芯材に対して、温度360℃、大気下で1時間保持することにより酸化処理を施し比較例6に係るキャリア芯材を得た。
Comparative example 6
The carrier core material obtained in Comparative Example 3 was subjected to an oxidation treatment by holding it at a temperature of 360° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 6.

比較例7
原料として、Fe(平均粒径:0.6μm)20.80kg、Mn(平均粒径:2μm)8.12kgを水11.50kg中に分散し、ポリカルボン酸アンモニウム系分散剤を180.0g、pH調整剤としてアンモニア水を10.0g、還元剤としてカーボンブラックを63.0g添加し、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。このスラリーにおける固形分濃度は75%、スラリー中原料粒径D50は0.6μm、D90は1.5μmであった。
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、乾燥造粒粉を得た。なお、このとき、目的の粒度分布以外の造粒粉は篩により除去した。
この造粒粉を、電気焼成炉に投入し、温度1200℃で保持時間2.5時間として、本焼成を行った。その後酸素濃度1.30%で5.5時間かけて冷却した。得られた焼成物は解粒後に篩を用いて分級し、平均粒径34.0μm、粒径22μm以下の割合が1.1%のキャリア芯材を得た。得られたキャリア芯材に対して、温度410℃、大気下で1時間保持することにより酸化処理を施し、比較例7に係るキャリア芯材を得た。
Comparative example 7
As raw materials, 20.80 kg of Fe 2 O 3 (average particle size: 0.6 μm) and 8.12 kg of Mn 3 O 4 (average particle size: 2 μm) were dispersed in 11.50 kg of water to form an ammonium polycarboxylate dispersion. 180.0 g of the agent, 10.0 g of ammonia water as a pH adjuster, and 63.0 g of carbon black as a reducing agent were added and pulverized using a wet ball mill (media diameter: 2 mm) to obtain a mixed slurry. The solid content concentration in this slurry was 75%, the raw material particle size D50 in the slurry was 0.6 μm, and the D90 was 1.5 μm.
This mixed slurry was sprayed into hot air at about 130° C. using a spray dryer to obtain dry granulated powder. At this time, granulated powder other than the target particle size distribution was removed using a sieve.
This granulated powder was put into an electric firing furnace, and main firing was performed at a temperature of 1200° C. for a holding time of 2.5 hours. Thereafter, it was cooled for 5.5 hours at an oxygen concentration of 1.30%. The obtained fired product was disintegrated and then classified using a sieve to obtain a carrier core material having an average particle size of 34.0 μm and a proportion of 1.1% having a particle size of 22 μm or less. The obtained carrier core material was subjected to oxidation treatment by holding it at a temperature of 410° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 7.

比較例8
原料として、Fe(平均粒径:0.6μm)17.49kg、Mn(平均粒径:2μm)6.93kgを水8.70kg中に分散し、ポリカルボン酸アンモニウム系分散剤を166.0g、SrFe1219(平均粒径:5μm)1.88kgを添加し、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。このスラリーにおける固形分濃度は75%、スラリー中原料粒径D50は0.6μm、D90は1.8μmであった。
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、乾燥造粒粉を得た。なお、このとき、目的の粒度分布以外の造粒粉は篩により除去した。
この造粒粉を、電気焼成炉に投入し、温度1225℃で保持時間2.5時間として、本焼成を行った。その後酸素濃度0.35%で5.5時間かけて冷却した。得られた焼成物は解粒後に篩を用いて分級し、平均粒径34.8μm、粒径22μm以下の割合が1.1%のキャリア芯材を得た。得られたキャリア芯材に対して、温度425℃、大気下で1時間保持することにより酸化処理を施し、比較例8に係るキャリア芯材を得た。
Comparative example 8
As raw materials, 17.49 kg of Fe 2 O 3 (average particle size: 0.6 μm) and 6.93 kg of Mn 3 O 4 (average particle size: 2 μm) were dispersed in 8.70 kg of water to form an ammonium polycarboxylate-based dispersion. 166.0 g of the agent and 1.88 kg of SrFe 12 O 19 (average particle size: 5 μm) were added and pulverized using a wet ball mill (media diameter: 2 mm) to obtain a mixed slurry. The solid content concentration in this slurry was 75%, the raw material particle size D50 in the slurry was 0.6 μm, and the D90 was 1.8 μm.
This mixed slurry was sprayed into hot air at about 130° C. using a spray dryer to obtain dry granulated powder. At this time, granulated powder other than the target particle size distribution was removed using a sieve.
This granulated powder was put into an electric firing furnace, and main firing was performed at a temperature of 1225° C. for a holding time of 2.5 hours. Thereafter, it was cooled for 5.5 hours at an oxygen concentration of 0.35%. The obtained fired product was cracked and then classified using a sieve to obtain a carrier core material having an average particle size of 34.8 μm and a proportion of 1.1% having a particle size of 22 μm or less. The obtained carrier core material was subjected to oxidation treatment by holding it at a temperature of 425° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 8.

比較例9
本焼成後の酸素濃度を0.70%で5.5時間かけて冷却した以外は、比較例8と同様にして、平均粒径34.4μm、粒径22μm以下の割合が1.2%のキャリア芯材を得た。得られたキャリア芯材に対して、温度500℃、大気下で1時間保持することにより酸化処理を施し、比較例9に係るキャリア芯材を得た。
Comparative example 9
The procedure was the same as in Comparative Example 8 except that the oxygen concentration after main firing was 0.70% and cooling was performed over 5.5 hours. A carrier core material was obtained. The obtained carrier core material was subjected to oxidation treatment by holding it at a temperature of 500° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 9.

比較例10
原料として、Fe(平均粒径:0.6μm)15.00kg、Mn(平均粒径:2μm)5.86kgを水5.22kg中に分散し、ポリカルボン酸アンモニウム系分散剤を129.8g、SrCO(平均粒径:0.6μm)170.0gを添加し、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。このスラリーにおける固形分濃度は79.5%、スラリー中原料粒径D50は0.6μm、D90は1.4μmであった。
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、乾燥造粒粉を得た。なお、このとき、目的の粒度分布以外の造粒粉は篩により除去した。
この造粒粉を、電気焼成炉に投入し、温度1225℃で保持時間2.5時間として、本焼成を行った。その後酸素濃度0.35%で5.5時間かけて冷却した。得られた焼成物は解粒後に篩を用いて分級し、平均粒径35.7μm、粒径22μm以下の割合が1.2%のキャリア芯材を得た。得られたキャリア芯材に対して、温度425℃、大気下で1時間保持することにより酸化処理を施し、比較例10に係るキャリア芯材を得た。
Comparative example 10
As raw materials, 15.00 kg of Fe 2 O 3 (average particle size: 0.6 μm) and 5.86 kg of Mn 3 O 4 (average particle size: 2 μm) were dispersed in 5.22 kg of water to form an ammonium polycarboxylate dispersion. 129.8 g of the agent and 170.0 g of SrCO 3 (average particle size: 0.6 μm) were added and pulverized using a wet ball mill (media diameter: 2 mm) to obtain a mixed slurry. The solid content concentration in this slurry was 79.5%, the raw material particle size D50 in the slurry was 0.6 μm, and the D90 was 1.4 μm.
This mixed slurry was sprayed into hot air at about 130° C. using a spray dryer to obtain dry granulated powder. At this time, granulated powder other than the target particle size distribution was removed using a sieve.
This granulated powder was put into an electric firing furnace, and main firing was performed at a temperature of 1225° C. for a holding time of 2.5 hours. Thereafter, it was cooled for 5.5 hours at an oxygen concentration of 0.35%. The obtained fired product was cracked and classified using a sieve to obtain a carrier core material having an average particle size of 35.7 μm and a proportion of 1.2% having a particle size of 22 μm or less. The obtained carrier core material was subjected to oxidation treatment by holding it at a temperature of 425° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 10.

比較例11
比較例10と同様にして、平均粒径35.6μm、粒径22μm以下の割合が1.1%粒径22μm以下の割合が1.1%のキャリア芯材を得た。得られたキャリア芯材に対して、温度500℃、大気下で1時間保持することにより酸化処理を施し、比較例11に係るキャリア芯材を得た。
Comparative example 11
In the same manner as Comparative Example 10, a carrier core material was obtained in which the average particle size was 35.6 μm, the proportion of particles with a particle size of 22 μm or less was 1.1%, and the proportion of particles with a particle size of 22 μm or less was 1.1%. The obtained carrier core material was subjected to oxidation treatment by holding it at a temperature of 500° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 11.

比較例12
比較例10と同様にして、平均粒径35、8μm、粒径22μm以下の割合が0.6%のキャリア芯材を得た。得られたキャリア芯材に対して、温度500℃、大気下で1時間保持することにより酸化処理を施し、比較例12に係るキャリア芯材を得た。
Comparative example 12
In the same manner as Comparative Example 10, a carrier core material having an average particle size of 35.8 μm and a proportion of 0.6% having a particle size of 22 μm or less was obtained. The obtained carrier core material was subjected to an oxidation treatment by holding it at a temperature of 500° C. in the atmosphere for 1 hour to obtain a carrier core material according to Comparative Example 12.

(見掛け密度(AD))
キャリア芯材の見掛け密度はJIS Z 2504に準拠して測定した。
(Apparent density (AD))
The apparent density of the carrier core material was measured in accordance with JIS Z 2504.

(流動度(FR))
キャリア芯材の流動度はJIS Z 2502に準拠して測定した。
(Flow rate (FR))
The fluidity of the carrier core material was measured in accordance with JIS Z 2502.

(体積平均粒子径(D50)及び粒径22μm以下の割合(%))
キャリア芯材の体積平均粒子径は、レーザー回折式粒度分布測定装置(日機装社製「マイクロトラックModel9320-X100」)を用いて測定した。
(Volume average particle diameter (D 50 ) and proportion (%) of particle diameters of 22 μm or less)
The volume average particle diameter of the carrier core material was measured using a laser diffraction particle size distribution analyzer ("Microtrac Model 9320-X100" manufactured by Nikkiso Co., Ltd.).

(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、外部磁場を0~79.58×10A/m(10000エルステッド)の範囲で1サイクル連続的に印加して、飽和磁化σ、残留磁化σ、保持力H及び磁場79.58×10A/m(1,000エルステッド)を印加した際の磁化σ1k(Am/kg)を測定した。
(Magnetic properties)
Using a vibrating sample magnetometer (VSM) dedicated to room temperature (VSM-P7 manufactured by Toei Kogyo Co., Ltd.), an external magnetic field was applied continuously for one cycle in the range of 0 to 79.58 x 10 4 A/m (10,000 Oe). The magnetization σ 1k (Am 2 / kg ) was measured.

(静的電気抵抗)
電極として表面を電解研磨した板厚2mmの真鍮板2枚を電極間距離が2mmとなるように配置し、2枚の電極板の間の空隙にキャリア芯材200mgを装入したのち、それぞれの電極板の背後に断面積240mmの磁石を配置して電極間に被測定粉体のブリッジを形成させた状態で電極間に100V、500V、1000Vの直流電圧を印加し、キャリア芯材を流れる電流値を4端子法により測定し抵抗を求めた。(また、その電流値と、電極間距離2mmおよび断面積240mmからキャリア芯材の静的電気抵抗の体積抵抗率も算出可能である。)
(static electrical resistance)
Two 2 mm thick brass plates with electrolytically polished surfaces were arranged as electrodes so that the distance between the electrodes was 2 mm, and 200 mg of carrier core material was inserted into the gap between the two electrode plates. A magnet with a cross-sectional area of 240 mm 2 is placed behind the electrode to form a bridge of the powder to be measured between the electrodes, and DC voltages of 100 V, 500 V, and 1000 V are applied between the electrodes to determine the value of the current flowing through the carrier core material. was measured by the four-terminal method to determine the resistance. (In addition, the volume resistivity of the static electrical resistance of the carrier core material can also be calculated from the current value, the inter-electrode distance of 2 mm, and the cross-sectional area of 240 mm2 .)

(充填式電気抵抗)
断面積1.3cmの塩化ビニル製の円柱状パイプ(半径0.643cm)の底面に黄銅製底板電極を設置し、秤量したサンプル5gを投入したのち、黄銅製円柱状電極をパイプの上から挿入し、黄銅製底板電極と黄銅製円柱状電極でサンプルを挟み込む。その後、サンプル充填前の数値とサンプル充填後の黄銅製円柱状電極の端部位置から変異センサー値の差を算出し、試料層の厚さとした。その後、サンプルを充填した状態で電極間に100V、250V、500V、750V、1000Vの直流電圧を印加し、絶縁抵抗計(東亜電波工業製、Type SM-8215)を用いてキャリア芯材の抵抗値を測定した。そして下記式から比抵抗を算出した。
比抵抗(Ω・cm)=絶縁抵抗計の値(Ω)×試料層の断面積(cm2)÷試料層の厚さ(cm)
(Filled electrical resistance)
A brass bottom plate electrode was installed on the bottom of a vinyl chloride cylindrical pipe (radius 0.643cm) with a cross-sectional area of 1.3cm2 , and after 5g of the weighed sample was put in, the brass cylindrical electrode was placed from the top of the pipe. Insert the sample and sandwich it between the brass bottom plate electrode and the brass cylindrical electrode. Thereafter, the difference between the variation sensor values was calculated from the value before filling the sample and the end position of the brass cylindrical electrode after filling the sample, and was taken as the thickness of the sample layer. Then, with the sample filled, DC voltages of 100V, 250V, 500V, 750V, and 1000V were applied between the electrodes, and the resistance value of the carrier core material was measured using an insulation resistance meter (manufactured by Toa Denpa Kogyo, Type SM-8215). was measured. Then, the specific resistance was calculated from the following formula.
Specific resistance (Ω cm) = Insulation resistance meter value (Ω) × Cross-sectional area of sample layer (cm 2 ) ÷ Thickness of sample layer (cm)

(絶縁破壊電圧,BD)
電極として表面を電解研磨した板厚2mmの真鍮板2枚を電極間距離が2mmとなるように配置し、2枚の電極板の間の空隙にキャリア200mgを装入したのち、それぞれの電極板の背後に断面積240mmの磁石を配置して電極間に被測定粉体のブリッジを形成させた状態で電極間に直流電圧を100V~2000Vまで100Vごとに段階的に印加していき、電流値が100mAを超えた電圧を絶縁破壊電圧とした。2000Vで電流値が100mAを超えない場合は、絶縁破壊電圧を2000Vとした。
(Dielectric breakdown voltage, BD)
Two 2 mm thick brass plates with electrolytically polished surfaces were arranged as electrodes so that the distance between the electrodes was 2 mm, and after charging 200 mg of carrier into the gap between the two electrode plates, A magnet with a cross-sectional area of 240 mm 2 is placed on the electrode to form a bridge of the powder to be measured between the electrodes, and a DC voltage is applied between the electrodes in steps of 100 V from 100 V to 2000 V, and the current value is A voltage exceeding 100 mA was defined as a dielectric breakdown voltage. When the current value did not exceed 100 mA at 2000V, the breakdown voltage was set to 2000V.

(細孔容積)
評価装置は、Quantachrome社製のPOREMASTER-60GTを使用した。具体的には、測定条件としては、
Cell Stem Volume:0.5cm
Headpressure:20PSIA、
水銀の表面張力:485.00erg/cm
水銀の接触角:130.00degrees、
高圧測定モード:Fixed Rate、
Moter Speed:1、
高圧測定レンジ:20.00~10000.00PSI
とし、サンプル1.500gを秤量して0.5cm(cc)のセルに充填して測定を行った。また、10000PSI時の容積B(cm/g)から60PSI時の容積A(cm/g)を差し引いた値を、細孔容積とした。
(pore volume)
The evaluation device used was POREMASTER-60GT manufactured by Quantachrome. Specifically, the measurement conditions are:
Cell Stem Volume: 0.5cm3 ,
Headpressure: 20PSIA,
Surface tension of mercury: 485.00erg/cm 2 ,
Contact angle of mercury: 130.00 degrees,
High pressure measurement mode: Fixed Rate,
Motor Speed: 1,
High pressure measurement range: 20.00~10000.00PSI
Then, 1.500 g of the sample was weighed and filled into a 0.5 cm 3 (cc) cell for measurement. Further, the value obtained by subtracting the volume A (cm 3 /g) at 60 PSI from the volume B (cm 3 /g) at 10,000 PSI was defined as the pore volume.

(BET比表面積)
BET一点法比表面積測定装置(株式会社マウンテック製、型式:Macsorb HM model-1208)を用いて、サンプル5.00gを容積5cmのセルに充填し、200℃で、30分間脱気して測定を行った。
(BET specific surface area)
Using a BET single point specific surface area measuring device (manufactured by Mountec Co., Ltd., model: Macsorb HM model-1208), 5.00 g of sample was filled into a cell with a volume of 5 cm 3 and measured at 200 ° C. by degassing for 30 minutes. I did it.

(真密度)
キャリア芯材の真密度は、Quantachrome社製、「ULTRA PYCNOMETER 1000」を用いて測定を行った。
(true density)
The true density of the carrier core material was measured using "ULTRA PYCNOMETER 1000" manufactured by Quantachrome.

(最大山谷深さRz,平均長さRSm,歪度Rsk)
超深度カラー3D形状測定顕微鏡(「VK-X100」株式会社キーエンス製)を用い、100倍対物レンズで表面を観察して求めた。具体的には、まず、表面の平坦な粘着テープにフェライト粒子を固定し、100倍対物レンズで測定視野を決定した後、オートフォーカス機能を用いて焦点を粘着テープ面に調整した。フェライト粒子を固定した平坦な粘着テープ面に対し、垂直方向(Z方向)からレーザー光線を照射し、面のX方向Y方向に走査した。また、表面からの反射光の強度が最大となった時のレンズの高さ位置をつなぎ合わせることでZ方向のデータを取得した。これらX、YおよびZ方向の位置データをつなぎ合わせフェライト粒子表面の3次元形状を得た。なお、フェライト粒子表面の3次元形状の取り込みにはオート撮影機能を用いた。
各パラメータの測定には、粒子粗さ検査ソフトウェア(三谷商事製)を用いて行った。まず、前処理として、得られたフェライト粒子表面の3次元形状の粒子認識と形状選別を行った。粒子認識は以下の方法で行った。撮影によって得られた3次元形状のうち、Z方向の最大値を100%、最小値を0%として最大値から最小値までの間を100等分する。この100~35%にあたる領域を抽出し、独立した領域の輪郭を粒子輪郭として認識した。次に形状選別で粗大、微小、会合などの粒子を除外した。この形状選別を行うことで以降に行う極率補正時の誤差を小さくすることができる。具体的には面積相当径28μm以下、38μm以上、針状比1.15以上に該当する粒子を除外した。また、比較例4及び比較例5に関しては、D50に合わせて面積相当径35μm以下、45μm以上、針状比1.15以上に該当する粒子を除外した。ここで針状比とは粒子の最大長/対角幅の比から算出したパラメータであり、対角幅とは最大長に平行な2本の直線で粒子を挟んだときの2直線の最短距離を表す。
つぎに表面の3次元形状から解析に用いる部分の取り出しを行った。まず上記の方法で認識した粒子輪郭から求められる重心を中心として15.0μmの正方形を描く。描いた正方形の中に21本の平行線を引き、その線分上にあたる粗さ曲線を21本分取り出した。
キャリア芯材は略球形状であるため、取り出した粗さ曲線は、バックグラウンドとして一定の曲率を持っている。このため、バックグラウンドの補正として、最適な二次曲線をフィッティングし、粗さ曲線から差し引く補正を行った。この場合、ローパスフィルターを1.5μmの強度で適用し、カットオフ値λを80μmとした。
(Maximum peak and valley depth Rz, average length RSm, skewness Rsk)
It was determined by observing the surface with a 100x objective lens using an ultra-deep color 3D shape measuring microscope ("VK-X100" manufactured by Keyence Corporation). Specifically, first, ferrite particles were fixed on an adhesive tape with a flat surface, a measurement field of view was determined using a 100x objective lens, and then the focus was adjusted to the adhesive tape surface using an autofocus function. A laser beam was irradiated from the perpendicular direction (Z direction) to the flat adhesive tape surface on which ferrite particles were fixed, and the surface was scanned in the X and Y directions. In addition, data in the Z direction was obtained by connecting the height positions of the lenses when the intensity of the reflected light from the surface was at its maximum. These positional data in the X, Y, and Z directions were connected to obtain the three-dimensional shape of the ferrite particle surface. Note that an automatic photographing function was used to capture the three-dimensional shape of the ferrite particle surface.
Each parameter was measured using particle roughness inspection software (manufactured by Mitani Shoji). First, as a pretreatment, particle recognition and shape selection of the three-dimensional shape of the surface of the obtained ferrite particles were performed. Particle recognition was performed using the following method. Of the three-dimensional shape obtained by photographing, the maximum value in the Z direction is taken as 100% and the minimum value as 0%, and the area from the maximum value to the minimum value is divided into 100 equal parts. A region corresponding to 100% to 35% of this was extracted, and the outline of the independent region was recognized as a particle outline. Next, coarse, minute, and aggregated particles were excluded by shape sorting. By performing this shape selection, it is possible to reduce errors during polarity correction performed later. Specifically, particles with an equivalent area diameter of 28 μm or less, 38 μm or more, and an acicular ratio of 1.15 or more were excluded. Furthermore, regarding Comparative Examples 4 and 5, particles with equivalent area diameter of 35 μm or less, 45 μm or more, and acicular ratio of 1.15 or more were excluded in accordance with D50 . Here, the acicular ratio is a parameter calculated from the ratio of maximum length/diagonal width of a particle, and diagonal width is the shortest distance between two straight lines when a particle is sandwiched between two straight lines parallel to the maximum length. represents.
Next, we extracted the parts to be used for analysis from the three-dimensional shape of the surface. First, a square of 15.0 μm is drawn centered on the center of gravity determined from the particle contour recognized by the above method. Twenty-one parallel lines were drawn inside the drawn square, and 21 roughness curves corresponding to the line segments were extracted.
Since the carrier core material has a substantially spherical shape, the extracted roughness curve has a constant curvature as a background. Therefore, as a background correction, an optimal quadratic curve was fitted and subtracted from the roughness curve. In this case, a low pass filter was applied with an intensity of 1.5 μm and a cutoff value λ of 80 μm.

最大山谷深さRzは、粗さ曲線の中で最も高い山の高さと最も深い谷の深さの和として求めた。以上説明した最大高さRzの測定は、JIS B0601(2001年度版)に準拠して行われるものである。最大高さRzの算出には、各パラメータの平均値として、50粒子の平均値を用いることとした。 The maximum peak and valley depth Rz was determined as the sum of the height of the highest peak and the depth of the deepest valley in the roughness curve. The measurement of the maximum height Rz explained above is performed in accordance with JIS B0601 (2001 edition). In calculating the maximum height Rz, the average value of 50 particles was used as the average value of each parameter.

平均長さRSmは、粗さ曲線のうち、谷と山の組み合わせを一つの要素と規定し、それぞれの要素の長さを平均したものである。以上説明した平均長さRSmの測定は、JIS B0601(2001年度版)に準拠して行われるものである。平均長さRSmの算出には、各パラメータの平均値として、50粒子の平均値を用いることとした。 The average length RSm defines a combination of valleys and peaks as one element in the roughness curve, and is the average length of each element. The measurement of the average length RSm explained above is performed in accordance with JIS B0601 (2001 edition). In calculating the average length RSm, the average value of 50 particles was used as the average value of each parameter.

(歪度Rsk)
歪度Rskについては、粗さ曲線を以下の数1に示す式にあてはめて算出した。
(skewness Rsk)
The skewness Rsk was calculated by applying the roughness curve to the equation shown in Equation 1 below.

ここで、数1の式中、Rnは、基準長さ15μmにおけるn番目の山または谷の平均線との差異を示し、二乗平均平方根高さRqは以下の数2に示す式によって求められる。 Here, in Equation 1, Rn indicates the difference from the average line of the n-th peak or valley at the reference length of 15 μm, and the root mean square height Rq is determined by the equation shown in Equation 2 below.

ここで、得られた歪度Rskは、その値が大きいほど、谷に位置する領域に偏ることを示すものである。 Here, the obtained skewness Rsk indicates that the larger the value, the more biased it is toward the region located in the valley.

(現像メモリ)
得られたキャリア芯材の表面を樹脂で被覆してキャリアを作製した。具体的には、シリコーン樹脂450質量部と、(2-アミノエチル)アミノプロピルトリメトキシシラン9質量部とを、溶媒としてのトルエン450質量部に溶解してコート溶液を作製した。このコート溶液を、流動床型コーティング装置を用いてキャリア芯材50000質量部に塗布し、温度300℃の電気炉で加熱してキャリアを得た。以下、全ての実施例、比較例についても同様にしてキャリアを得た。
得られたキャリアと平均粒径5.0μm程度のトナーとを、ポットミルを用いて所定時間混合し、二成分系の電子写真現像剤を得た。この場合、キャリアとトナーとをトナーの重量/(トナーおよびキャリアの重量)=5/100となるように調整した。以下、全ての実施例、比較例についても同様にして現像剤を得た。得られた現像剤を、図1に示す構造の現像装置(現像ローラの周速度Vs:406mm/sec,感光体ドラムの周速度Vp:205mm/sec,感光体ドラム-現像ローラ間距離:0.3mm)に投入し、感光体ドラムの長手方向にベタ画像部と非画像部とが隣り合い、その後は広い面積の中間調が続く画像を初期と20万枚画像形成後に取得し、現像ローラ2周目の現像ローラ1周目のベタ画像が現像された領域とそうでない領域との画像濃度を反射濃度計(東京電色社製の型番TC-6D)を用いて測定し、その差を求め下記基準で評価した。
「○」:0.006未満
「△」:0.006以上0.020未満
「×」:0.020以上
(Development memory)
The surface of the obtained carrier core material was coated with a resin to produce a carrier. Specifically, 450 parts by mass of silicone resin and 9 parts by mass of (2-aminoethyl)aminopropyltrimethoxysilane were dissolved in 450 parts by mass of toluene as a solvent to prepare a coating solution. This coating solution was applied to 50,000 parts by mass of a carrier core material using a fluidized bed coating device, and heated in an electric furnace at a temperature of 300° C. to obtain a carrier. Hereinafter, carriers were obtained in the same manner for all Examples and Comparative Examples.
The obtained carrier and toner having an average particle size of about 5.0 μm were mixed for a predetermined time using a pot mill to obtain a two-component electrophotographic developer. In this case, the carrier and toner were adjusted so that the weight of toner/(weight of toner and carrier)=5/100. Developers were obtained in the same manner for all Examples and Comparative Examples. The obtained developer was used in a developing device having the structure shown in FIG. 1 (peripheral speed Vs of the developing roller: 406 mm/sec, circumferential speed Vp of the photosensitive drum: 205 mm/sec, distance between the photosensitive drum and the developing roller: 0. 3 mm), the solid image area and the non-image area are adjacent to each other in the longitudinal direction of the photoreceptor drum, and then images with a wide area of intermediate tones are obtained at the initial stage and after the image formation of 200,000 sheets. Using a reflection densitometer (model number TC-6D, manufactured by Tokyo Denshoku Co., Ltd.), measure the image density between the area where the solid image was developed and the area where the solid image was not developed during the first rotation of the developing roller, and find the difference. Evaluation was made using the following criteria.
“○”: Less than 0.006 “△”: 0.006 or more and less than 0.020 “×”: 0.020 or more

(くみ上げ量)
小型現像装置(ローラ径:16mm、溝形ローラ、非磁性規制板ギャップ0.6mm)に、作成した二成分現像剤を80g投入し、ローラ回転数250rpmで3分間撹拌した後、現像ローラに横4cm縦1cmで両端円形にくりぬいた面積3.785cmのパッチをあて、フィルター付き吸引装置を用いてパッチ内の現像剤を吸引してフィルターに回収した。回収前後でのフィルターの重量を測定し、フィルターの重量差を求め、下記式から単位面積当たりのくみ上げ量を算出し下記基準で評価した。
単位面積当たりのくみ上げ量=(現像剤くみ上げ量)÷3.785cm
「〇」:50mg/□cm以上
「×」:50mg/□cm未満
(Amount pumped)
80g of the prepared two-component developer was put into a small developing device (roller diameter: 16mm, grooved roller, non-magnetic regulating plate gap 0.6mm), stirred at a roller rotation speed of 250 rpm for 3 minutes, and then placed horizontally on the developing roller. A patch with an area of 3.785 cm 2 , which was 4 cm long and 1 cm long and circularly cut out at both ends, was applied, and a suction device with a filter was used to suck the developer in the patch and collect it in a filter. The weight of the filter before and after collection was measured, the difference in weight of the filter was determined, and the amount pumped per unit area was calculated from the following formula, and evaluated using the following criteria.
Pumping amount per unit area = (Developer pumping amount) ÷ 3.785 cm 2
"〇": 50mg/□cm 2 or more "×": 50mg/□cm less than 2

表1及び表2に示されるように、本発明に係るキャリア芯材を用いた実施例~8の樹脂被覆キャリアでは現像ローラへのくみ上げ量は十分にあり、また現像メモリの発生も見られなかった。また実施例5~8の樹脂被覆キャリアについてキャリア付着(感光体ドラムの非画像形成領域にキャリアが付着する不具合現象)についても観察したところ、これらの実施例の樹脂被覆キャリアではキャリア付着は見られなかった。 As shown in Tables 1 and 2, the resin-coated carriers of Examples 5 to 8 using the carrier core material according to the present invention had a sufficient amount of pumping to the developing roller, and no development memory was observed. There wasn't. We also observed carrier adhesion (a defective phenomenon in which carrier adheres to the non-image forming area of the photoreceptor drum) on the resin-coated carriers of Examples 5 to 8, and found that no carrier adhesion was observed in the resin-coated carriers of these Examples. There wasn't.

これに対して、PV×σから求められた値が0.008未満であると小さい比較例1~12の樹脂被覆キャリアではいずれも現像ローラへのくみ上げ量が少なかった。また粒子の最大山谷深さRzが1.24μm及び1.25μmと小さい比較例4及び比較例5の樹脂被覆キャリアでは現像メモリの発生も見られた。 On the other hand, in all of the resin-coated carriers of Comparative Examples 1 to 12, where the value calculated from PV×σ r was less than 0.008, the amount pumped up to the developing roller was small. In addition, development memory was also observed in the resin-coated carriers of Comparative Examples 4 and 5, in which the maximum peak-to-valley depths Rz of the particles were small, 1.24 μm and 1.25 μm.

本発明に係るキャリア芯材によれ現像ローラへのくみ上げが効果的に行われ、また現像メモリが抑制できる。 With the carrier core material according to the present invention, pumping to the developing roller is effectively performed and development memory can be suppressed.

3 現像ローラ
5 感光体ドラム
3 Developing roller 5 Photosensitive drum

Claims (4)

フェライトキャリア芯材であって、
細孔容積PV(cm/g)と残留磁化σ(Am/kg)との積PV×σ0.050以上0.065以下の範囲であり、
粒子の最大山谷深さRzが1.4μm以上3.0μm以下である
ことを特徴とするフェライトキャリア芯材。
A ferrite carrier core material,
The product PV x σ r of pore volume PV (cm 3 /g) and residual magnetization σ r (Am 2 /kg) is in the range of 0.050 or more and 0.065 or less ,
The maximum peak and valley depth Rz of particles is 1.4 μm or more and 3.0 μm or less
A ferrite carrier core material characterized by:
(MnMg)Fe3-(x+y)(但し、0.1<x≦1,0.1<y≦1である。)で表される組成を有し、
Mn,Mg,Feの総mol数に対してCaが0.10mol%超1.0mol%未満の範囲含有されている請求項1に記載のフェライトキャリア芯材。
(Mn x Mg y ) Fe 3-(x+y) O 4 (where 0.1<x≦1, 0.1<y≦1),
The ferrite carrier core material according to claim 1, wherein Ca is contained in a range of more than 0.10 mol% and less than 1.0 mol% with respect to the total mol number of Mn, Mg, and Fe.
請求項1又は2に記載のフェライトキャリア芯材の表面が樹脂で被覆されていることを特徴とする電子写真現像用キャリア。 A carrier for electrophotographic development, characterized in that the surface of the ferrite carrier core material according to claim 1 or 2 is coated with a resin. 請求項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。 An electrophotographic developer comprising the carrier for electrophotographic development according to claim 3 and a toner.
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