JP5348588B2 - Carrier core material for electrophotographic developer, carrier, production method thereof, and electrophotographic developer using the carrier - Google Patents

Carrier core material for electrophotographic developer, carrier, production method thereof, and electrophotographic developer using the carrier Download PDF

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JP5348588B2
JP5348588B2 JP2009092677A JP2009092677A JP5348588B2 JP 5348588 B2 JP5348588 B2 JP 5348588B2 JP 2009092677 A JP2009092677 A JP 2009092677A JP 2009092677 A JP2009092677 A JP 2009092677A JP 5348588 B2 JP5348588 B2 JP 5348588B2
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electrophotographic developer
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resin
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JP2010243798A (en
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隆志 小島
享 岩田
康二 安賀
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Powdertech Co Ltd
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a carrier core material, a carrier and the like for electrophotographic developer which is highly magnetized without using heavy metals except Mn substantially and exhibits a desired resistance of middle or high resistance and is superior in charging characteristics and has a uniform shape provided with a proper concave-convex surface. <P>SOLUTION: The carrier core material for electrophotographic developer contains 0.8 to 5 wt.% Mg, 0.1 to 2.5 wt.% Ti, 60 to 70 wt.% Fe, and 0.2 to 2.5 wt.% Sr and has a surface coating formed on particle surfaces by surface oxidation treatment, and a ratio (a) of roughness R<SB>a after treatment</SB>of a core material surface after the surface oxidation treatment to roughness R<SB>a before treatment</SB>of the core material surface before the surface oxidation treatment satisfies 2.3&ge;R<SB>a after treatment</SB>/R<SB>a before treatment</SB>&gt;1, and Si is eluted in a pH4 standard solution by 50 to 1,000 ppm, and the carrier core material has a shape factor SF-2 (roundness) of 100 to 120. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

本発明は、複写機、プリンター等に用いられる二成分系電子写真現像剤に使用される電子写真現像剤用キャリア芯材、キャリア及びこれらの製造方法、並びに該キャリアを用いた電子写真現像剤に関する。   The present invention relates to a carrier core material for an electrophotographic developer used in a two-component electrophotographic developer used in a copying machine, a printer, and the like, a carrier, a production method thereof, and an electrophotographic developer using the carrier. .

電子写真現像方法は、現像剤中のトナー粒子を感光体上に形成された静電潜像に付着させて現像する方法であり、この方法で使用される現像剤は、トナー粒子とキャリア粒子からなる二成分系現像剤及びトナー粒子のみを用いる一成分系現像剤に分けられる。   The electrophotographic development method is a method in which toner particles in a developer are attached to an electrostatic latent image formed on a photoreceptor and developed, and the developer used in this method is composed of toner particles and carrier particles. The two-component developer and the one-component developer using only toner particles.

こうした現像剤のうち、トナー粒子とキャリア粒子からなる二成分系現像剤を用いた現像方法としては、古くはカスケード法等が採用されていたが、現在では、マグネットロールを用いる磁気ブラシ法が主流である。   Among these developers, as a developing method using a two-component developer composed of toner particles and carrier particles, the cascade method has been used in the past, but at present, the magnetic brush method using a magnet roll is the mainstream. It is.

二成分系現像剤において、キャリア粒子は、現像剤が充填されている現像ボックス内において、トナー粒子と共に攪拌されることによって、トナー粒子に所望の電荷を付与し、さらにこのように電荷を帯びたトナー粒子を感光体の表面に搬送して感光体上にトナー像を形成するための担体物質である。マグネットを保持する現像ロール上に残ったキャリア粒子は、この現像ロールから再び現像ボックス内に戻り、新たなトナー粒子と混合・攪拌され、一定期間繰り返して使用される。   In the two-component developer, the carrier particles are agitated together with the toner particles in the developing box filled with the developer, thereby imparting a desired charge to the toner particles, and thus being charged. A carrier material for transporting toner particles to the surface of the photoreceptor to form a toner image on the photoreceptor. The carrier particles remaining on the developing roll holding the magnet are returned to the developing box from the developing roll, mixed and stirred with new toner particles, and used repeatedly for a certain period.

二成分系現像剤は、一成分系現像剤とは異なり、キャリア粒子はトナー粒子と混合・攪拌され、トナー粒子を帯電させ、さらに搬送する機能を有しており、現像剤を設計する際の制御性が良い。従って、二成分系現像剤は高画質が要求されるフルカラー現像装置及び画像維持の信頼性、耐久性が要求される高速印刷を行う装置等に適している。   Unlike the one-component developer, the two-component developer has the function of mixing and stirring the carrier particles with the toner particles, charging the toner particles, and further transporting the toner particles. Good controllability. Therefore, the two-component developer is suitable for a full-color developing device that requires high image quality and a device that performs high-speed printing that requires image maintenance reliability and durability.

このようにして用いられる二成分系現像剤においては、画像濃度、カブリ、白斑、階調性、解像力等の画像特性が、初期の段階から所定の値を示し、しかもこれらの特性が耐刷期間中に変動せず、安定に維持されることが必要である。これらの特性を安定に維持するためには、二成分系現像剤中に含有されるキャリア粒子の特性が安定していることが必要になる。   In the two-component developer used in this manner, image characteristics such as image density, fog, vitiligo, gradation, and resolving power show predetermined values from the initial stage, and these characteristics are in the printing life period. It needs to be kept stable without fluctuating inside. In order to maintain these characteristics stably, it is necessary that the characteristics of the carrier particles contained in the two-component developer are stable.

二成分系現像剤を形成するキャリア粒子として、従来は、表面を酸化被膜で覆った鉄粉あるいは表面を樹脂で被覆した鉄粉等の鉄粉キャリアが使用されていた。このような鉄粉キャリアは、磁化が高く、導電性も高いことから、ベタ部の再現性のよい画像が得られやすいという利点がある。   Conventionally, iron powder carriers such as iron powder whose surface is covered with an oxide film or iron powder whose surface is coated with a resin have been used as carrier particles for forming a two-component developer. Since such an iron powder carrier has high magnetization and high conductivity, there is an advantage that an image with a good reproducibility of the solid portion can be easily obtained.

しかしながら、このような鉄粉キャリアは真比重が約７．８と重く、また磁化が高すぎることから、現像ボックス中におけるトナー粒子との攪拌・混合により、鉄粉キャリア表面へのトナー構成成分の融着、いわゆるトナースペントが発生しやすくなる。このようなトナースペントの発生により有効なキャリア表面積が減少し、トナー粒子との摩擦帯電能力が低下しやすくなる。   However, such an iron powder carrier has a heavy true specific gravity of about 7.8 and is too high in magnetization, so that the toner constituent components on the surface of the iron powder carrier are mixed by stirring and mixing with toner particles in the developing box. Fusing, so-called toner spent, is likely to occur. The generation of such toner spent reduces the effective carrier surface area and tends to reduce the triboelectric charging ability with the toner particles.

また、樹脂被覆鉄粉キャリアでは、耐久時のストレスにより表面の樹脂が剥離し、高導電性で絶縁破壊電圧が低い芯材（鉄粉）が露出することにより、電荷のリークが生ずることがある。このような電荷のリークにより、感光体上に形成された静電潜像が破壊され、ベタ部にハケスジ等が発生し、均一な画像が得られにくい。これらの理由から、酸化被膜鉄粉及び樹脂被覆鉄粉等の鉄粉キャリアは、現在では使用されなくなってきている。   Moreover, in the resin-coated iron powder carrier, the resin on the surface peels off due to stress during durability, and the core material (iron powder) with high conductivity and low dielectric breakdown voltage is exposed, which may cause charge leakage. . Due to such charge leakage, the electrostatic latent image formed on the photoconductor is destroyed, and a crack or the like is generated in the solid portion, so that it is difficult to obtain a uniform image. For these reasons, iron powder carriers such as oxide-coated iron powder and resin-coated iron powder are no longer used.

近年は、鉄粉キャリアに代わって真比重約５．０程度と軽く、また磁化も低いフェライトをキャリアとして用いたり、さらに表面に樹脂を被覆した樹脂コートフェライトキャリアが多く使用されており、現像剤寿命は飛躍的に伸びてきた。   In recent years, instead of iron powder carriers, ferrite with a true specific gravity of about 5.0, which is light and has a low magnetization, or a resin-coated ferrite carrier whose surface is coated with a resin has been widely used. Lifespan has increased dramatically.

このようなフェライトキャリアの製造方法としては、フェライトキャリア原料を所定量混合した後、仮焼、粉砕し、造粒後に焼成を行うのが一般的であり、条件によっては仮焼を省略できる場合もある。   As a method for producing such a ferrite carrier, a predetermined amount of ferrite carrier raw material is mixed, calcined, pulverized, and then fired after granulation. Depending on conditions, calcining may be omitted. is there.

ところで、最近、環境規制が厳しくなり、Ｎｉ、Ｃｕ、Ｚｎ等の金属の使用は避けられるようになってきており、環境規制に適応した金属の使用が求められており、キャリア芯材として用いられるフェライト組成はＣｕ−Ｚｎフェライト、Ｎｉ−ＺｎフェライトからＭｎを用いたマンガンフェライト、Ｍｎ−Ｍｇ−Ｓｒフェライト等に移行している。   Recently, environmental regulations have become stricter, and the use of metals such as Ni, Cu, and Zn has been avoided, and the use of metals suitable for environmental regulations has been demanded, and it is used as a carrier core material. The ferrite composition has shifted from Cu-Zn ferrite, Ni-Zn ferrite to manganese ferrite using Mn, Mn-Mg-Sr ferrite, and the like.

特許文献１（特開２００６−３３７８２８号公報）には、表面が溝又は筋で１０μｍ四方あたり２〜５０の領域に分割されており、マンガンフェライトを主成分とする電子写真用フェライトキャリア芯材が記載されている。このフェライトキャリア芯材は、組成が均一で、一定の表面性、良好な流動性を有し、かつ高磁化、低抵抗であり、このフェライトキャリア芯材に樹脂を被覆したフェライトキャリアを用いた電子写真用現像剤は、帯電の立ち上がりが速く、経時における安定した帯電量を有するとされている。   Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-337828) discloses a ferrite carrier core material for electrophotography in which the surface is divided into regions of 2 to 50 per 10 μm square by grooves or streaks, and the main component is manganese ferrite. Have been described. This ferrite carrier core material has a uniform composition, constant surface properties, good fluidity, high magnetization, low resistance, and an electron using a ferrite carrier in which this ferrite carrier core material is coated with a resin. Photographic developers are said to have a fast charge rise and a stable charge over time.

この特許文献１では、上記のようなフェライトキャリア芯材を製造するために、ＦｅとＭｎのモル比（Ｆｅ／Ｍｎ）が４〜１６のＦｅとＭｎを主成分とする複合酸化物を粉砕、混合後、造粒、焼成し、さらに解砕、分級する製造方法において、焼成を酸素濃度が５体積％以下の雰囲気で行うことが示されている。   In Patent Document 1, in order to produce the ferrite carrier core material as described above, a composite oxide mainly composed of Fe and Mn having a molar ratio of Fe to Mn (Fe / Mn) of 4 to 16 is crushed. It has been shown that in a production method in which granulation, firing, and further pulverization and classification are performed after mixing, firing is performed in an atmosphere having an oxygen concentration of 5% by volume or less.

しかし、Ｍｎも各種法規制の対象になりつつあり、上記各種重金属はもとよりＭｎを使用しない新たなキャリア芯材が求められている。   However, Mn is also subject to various laws and regulations, and a new carrier core material that does not use Mn as well as the above various heavy metals is demanded.

Ｍｎを用いたキャリア芯材に代わるものとして、Ｍｇを用いたキャリア芯材が提案されている。例えば、特許文献２（特開２００５−１６２５９７号公報）には、式ＸａＭｇｂＦｅｃＣａｄＯｅ（ＸはＬｉ、Ｎａ、Ｔｉ等又はその組み合わせ）で示されるマグネシウム系フェライト材料（キャリア芯材）が示され、飽和磁化が３０〜８０ｅｍｕ／ｇ、絶縁破壊電圧が１．５〜５．０ｋＶであるとされ、このマグネシウム系フェライト材料により、高画質化と環境規制への対応を図ることができるとされている。 As an alternative to a carrier core material using Mn, a carrier core material using Mg has been proposed. For example, Patent Document 2 (JP 2005-162597), wherein X a Mg b Fe c Ca d O e (X is Li, Na, Ti, etc., or a combination thereof) magnesium-based ferrite material represented by (carrier Core material), saturation magnetization is 30 to 80 emu / g, and dielectric breakdown voltage is 1.5 to 5.0 kV. With this magnesium-based ferrite material, high image quality and compliance with environmental regulations are achieved. It is supposed to be possible.

また、特許文献３（特表２００６−５２４６２７号公報）には、式ＭｇａＦｅｂＣａｃＯｄで示されるマグネシウム系フェライト材料（キャリア芯材）が示され、飽和磁化が３０〜８０ｅｍｕ／ｇ、絶縁破壊電圧が１．５〜５．０ｋＶであるとされ、環境規制に対応したクリーンな材料で構成され、鮮明で階調性に富みカブリのない高画質像が得られるとされている。 Patent Document 3 (Japanese Patent Publication No. 2006-524627) discloses a magnesium-based ferrite material (carrier core material) represented by the formula Mg a Fe b Ca c O d and has a saturation magnetization of 30 to 80 emu / g. It is said that the dielectric breakdown voltage is 1.5 to 5.0 kV, and is composed of a clean material that complies with environmental regulations, and a high-quality image that is clear, rich in gradation, and free from fog is obtained.

このようにＭｇを用いたキャリア芯材は提案されているが、一般に磁化と抵抗はトレードオフの関係にあるため、高磁化と中抵抗〜高抵抗といった特性を両立することは難しい。そのため、Ｍｎを添加することで磁化と抵抗のトレードオフの関係を緩和し高磁化かつ中抵抗〜高抵抗を実現し、現在は電子写真現像剤用キャリア芯材として利用されている。しかしながら、上述したように、各種重金属規制の強化に伴いＭｎを使用しにくい状況となりつつある。   Thus, although the carrier core material using Mg is proposed, since magnetization and resistance are generally in a trade-off relationship, it is difficult to achieve both high magnetization and characteristics such as medium resistance to high resistance. Therefore, by adding Mn, the trade-off relationship between magnetization and resistance is relaxed to realize high magnetization, medium resistance to high resistance, and it is currently used as a carrier core material for electrophotographic developer. However, as described above, it is becoming difficult to use Mn with the strengthening of various heavy metal regulations.

また、Ｍｎを意図的に添加しないマグネシウム系キャリア芯材において、従来の焼成方法でも高磁化、かつ中抵抗〜高抵抗を実現する方法としては、本焼成後、表面酸化することで抵抗を所望のレベルに合わせ込む取り組みがなされてきたが、上記トレードオフの関係を十分解決できているとは言えない。   In addition, in a magnesium-based carrier core material in which Mn is not intentionally added, as a method for realizing high magnetization and medium resistance to high resistance even with a conventional firing method, a desired resistance can be obtained by surface oxidation after firing. Efforts to match the level have been made, but it cannot be said that the above trade-off relationship has been sufficiently solved.

また、従来よりマグネシウム系フェライトはＦｅ過剰で製造することで磁化を高くすることが出来ることが知られている。しかし、抵抗はＦｅ過剰であるため極めて低いものとなってしまっている。また、Ｆｅ過剰のマグネシウム系フェライトは、本焼成時の酸素濃度が高い場合や表面酸化によって磁化が急激に低くなると言う特徴を持っており、この現象はＦｅ３Ｏ４中に含まれる２価のＦｅの酸化によるものと考えられている。 Conventionally, it is known that magnesium-based ferrite can increase the magnetization by producing it in excess of Fe. However, the resistance is extremely low due to the excess of Fe. In addition, Fe-excess magnesium-based ferrite has a feature that the magnetization is drastically lowered due to high oxygen concentration during surface firing or surface oxidation, and this phenomenon is caused by the divalent content contained in Fe 3 O 4 . It is thought to be due to oxidation of Fe.

一方、Ｆｅ以外の遷移金属を含有しないマグネシウム系フェライトの焼成温度は１２５０〜１３５０℃程度ときわめて高温であり、キャリア芯材に求められる表面性はほとんど凹凸のないものしか得られないだけでなく、焼成時にキャリア芯材粒子同士が凝集しやすく球形ではない粒子が多く含まれることとなる。そのため、意図的に重金属を含有せず、高磁化、中抵抗〜高抵抗で、かつ適度な凹凸を有する表面性と揃った形状を実現した電子写真現像剤用キャリア芯材は得られていないのが現状である。   On the other hand, the firing temperature of the magnesium-based ferrite containing no transition metal other than Fe is as high as about 1250 to 1350 ° C., and not only the surface properties required for the carrier core material can be obtained with almost no unevenness, The carrier core particles are likely to aggregate during firing and contain many particles that are not spherical. Therefore, a carrier core material for an electrophotographic developer that does not intentionally contain a heavy metal, has a shape that has high magnetization, medium resistance to high resistance, and a surface property that has moderate unevenness has not been obtained. Is the current situation.

特許文献４（特許第２８６０３５６号公報）及び特許文献５（特許第３１５１４５７号公報）についてはＦｅ２Ｏ３（ヘマタイト）およびマグネシウムの混合物またはＦｅ２Ｏ３及びチタンの混合物を還元性ガスを用いて還元することが記載されているが、Ｆｅ２Ｏ３及びＦｅ３Ｏ４（マグネタイト）を還元することにより生成したＦｅＯ（ウスタイト）について記載はあるものの、後工程によりＦｅＯの存在量を制御し、抵抗及び磁化といった特性値を制御しようとするものではないため、後述する本発明の意図するところとは異なる。 For Patent Document 4 (Patent No. 2860356) and Patent Document 5 (Patent No. 3151457), a mixture of Fe 2 O 3 (hematite) and magnesium or a mixture of Fe 2 O 3 and titanium is used with a reducing gas. Although it is described to reduce, FeO (wustite) produced by reducing Fe 2 O 3 and Fe 3 O 4 (magnetite) is described, the amount of FeO is controlled by a post process, Since characteristic values such as resistance and magnetization are not intended to be controlled, they are different from those intended by the present invention described later.

特開２００６−３３７８２８号公報JP 2006-337828 A

特開２００５−１６２５９７号公報Japanese Patent Laid-Open No. 2005-162597

特表２００６−５２４６２７号公報JP 2006-524627 A

特許第２８６０３５６号公報Japanese Patent No. 2860356

特許第３１５１４５７号公報Japanese Patent No. 3151457

従って、本発明の目的は、Ｍｎを除く各重金属を実質的に用いることなしに、高磁化でありながら中抵抗又は高抵抗といった所望の抵抗が得られ、かつ帯電特性に優れ、しかも適度な凹凸を有する表面性と揃った形状とを兼備する電子写真現像剤用キャリア芯材、キャリア及びこれらの製造方法、並びに該キャリアを用いた長寿命化が達成され、かつ高い帯電量を有し、帯電安定性にも優れた電子写真現像剤を提供することにある。   Therefore, an object of the present invention is to obtain a desired resistance such as medium resistance or high resistance while being highly magnetized without substantially using each heavy metal excluding Mn, and excellent charging characteristics and moderate unevenness. A carrier core material for an electrophotographic developer that has both a surface property and a uniform shape, a carrier, a method for producing the same, a long life using the carrier, and a high charge amount. An object of the present invention is to provide an electrophotographic developer having excellent stability.

本発明者らは、上記のような課題を解決すべく鋭意検討した結果、Ｍｇ、Ｔｉ、Ｆｅ及びＳｒを一定量含有し、かつ表面酸化処理前の芯材表面粗さに対する表面酸化処理後の芯材表面粗さの比（ａ）が一定範囲にあり、かつＳｒのｐＨ４標準液による溶出量と形状係数ＳＦ−２（真円度）が特定範囲にあり、望ましくはマグネシウムフェライトを構成するスピネル構造以外に少なくともＦｅ及びＴｉを含有する酸化物の結晶構造を含有するキャリア芯材及びこれに樹脂を被覆したキャリアが上記目的を達成し得ることを知見し、本発明に至った。   As a result of intensive studies to solve the above-mentioned problems, the present inventors have contained a certain amount of Mg, Ti, Fe and Sr, and after the surface oxidation treatment with respect to the core surface roughness before the surface oxidation treatment. The ratio (a) of the surface roughness of the core material is in a certain range, the elution amount of Sr with a pH 4 standard solution and the shape factor SF-2 (roundness) are in a specific range, and preferably spinel constituting magnesium ferrite. In addition to the structure, the present inventors have found that a carrier core material containing a crystal structure of an oxide containing at least Fe and Ti and a carrier coated with a resin on the carrier core material can achieve the above object, and have reached the present invention.

すなわち、本発明は、Ｍｇを０．８〜５重量％、Ｔｉを０．１〜２．５重量％、Ｆｅを６０〜７０重量％及びＳｒを０．２〜２．５重量％含有し、表面酸化処理により表面被覆が形成されている電子写真現像剤用キャリア芯材であって、表面酸化処理前の芯材表面の粗さＲａ処理前に対する表面酸化処理後の芯材表面の粗さＲａ処理後の比（ａ）が、２．３≧Ｒａ処理後／Ｒａ処理前＞１であり、ＳｒのｐＨ４標準液による溶出が５０〜１０００ｐｐｍ、形状係数ＳＦ−２（真円度）が１００〜１２０であることを特徴とする電子写真現像剤用キャリア芯材を提供するものである。 That is, the present invention contains Mg 0.8 to 5 wt%, Ti 0.1 to 2.5 wt%, Fe 60 to 70 wt% and Sr 0.2 to 2.5 wt%, A carrier core material for an electrophotographic developer having a surface coating formed by a surface oxidation treatment, the surface roughness of the core material before the surface oxidation treatment before the surface oxidation treatment Ra of the core material surface after the surface oxidation treatment Ratio (a) after Ra treatment is 2.3 ≧ After Ra treatment / Before Ra treatment > 1, elution of Sr with pH 4 standard solution is 50 to 1000 ppm, shape factor SF-2 (roundness) ) Is 100 to 120. A carrier core material for an electrophotographic developer is provided.

本発明の上記電子写真現像剤用キャリア芯材は、上記表面酸化処理後のキャリア用芯材はＦｅ２Ｏ３成分が生成していることが望ましい。 In the carrier core material for an electrophotographic developer according to the present invention, it is desirable that an Fe 2 O 3 component is generated in the carrier core material after the surface oxidation treatment.

本発明の上記電子写真現像剤用キャリア芯材は、Ｍｇを含有するスピネル構造以外に少なくともＦｅ及びＴｉを含有する酸化物の結晶構造を含有することが望ましい。   The carrier core material for an electrophotographic developer according to the present invention preferably contains an oxide crystal structure containing at least Fe and Ti in addition to the spinel structure containing Mg.

本発明の上記電子写真現像剤用キャリア芯材は、２ｍｍＧａｐ印加電圧５００Ｖにおける抵抗が、５×１０７〜１×１０９Ωであることが望ましい。 The carrier core material for an electrophotographic developer according to the present invention preferably has a resistance of 5 × 10 7 to 1 × 10 9 Ω at a 2 mm Gap applied voltage of 500 V.

本発明の上記電子写真現像剤用キャリア芯材は、Ｍｎを含有し、その含有量が１０重量％以下であることが望ましい。   The carrier core material for an electrophotographic developer of the present invention preferably contains Mn and the content thereof is 10% by weight or less.

本発明の上記電子写真現像剤用キャリア芯材は、見掛け密度が２．３〜２．６ｇ／ｃｍ３であることが望ましい。 The carrier core material for an electrophotographic developer according to the present invention preferably has an apparent density of 2.3 to 2.6 g / cm 3 .

本発明の上記電子写真現像剤用キャリア芯材は、ＢＥＴ比表面積が０．０７５〜０．１５ｍ２／ｇであることが望ましい。 The carrier core material for an electrophotographic developer according to the present invention preferably has a BET specific surface area of 0.075 to 0.15 m 2 / g.

本発明の上記電子写真現像剤用キャリア芯材は、３Ｋ・１０００／４π・Ａ／ｍの磁場をかけたときの磁化が５０〜８５Ａｍ２／ｋｇであることが望ましい。 The carrier core material for an electrophotographic developer of the present invention preferably has a magnetization of 50 to 85 Am 2 / kg when a magnetic field of 3K · 1000 / 4π · A / m is applied.

本発明の上記電子写真現像剤用キャリア芯材は、レーザー回折式粒度分布測定装置により測定される平均粒径が１５〜１２０μｍであることが望ましい。   The carrier core material for an electrophotographic developer according to the present invention preferably has an average particle size of 15 to 120 μm as measured by a laser diffraction particle size distribution analyzer.

本発明は、上記キャリア芯材の表面が樹脂で被覆されている電子写真現像剤用キャリアを提供するものである。   The present invention provides a carrier for an electrophotographic developer in which the surface of the carrier core material is coated with a resin.

本発明の上記電子現像剤用キャリアにおいて、上記樹脂は、アクリル樹脂、シリコーン樹脂又は変性シリコーン樹脂であることが望ましい。   In the carrier for an electronic developer according to the present invention, the resin is preferably an acrylic resin, a silicone resin, or a modified silicone resin.

また、本発明は、Ｆｅ、Ｔｉ、Ｍｇ及びＳｒの各化合物を粉砕、混合、仮焼した後、再度粉砕、混合、造粒し、得られた造粒物を１次焼成、本焼成し、さらに解砕、分級、表面酸化処理する電子写真現像剤用キャリア芯材の製造方法であって、上記本焼成が、酸素濃度が５体積％以下で行われることを特徴とする電子写真現像剤用キャリア芯材の製造方法を提供するものである。   In the present invention, each compound of Fe, Ti, Mg and Sr is pulverized, mixed, calcined, then pulverized, mixed, granulated, and the resulting granulated product is subjected to primary firing, main firing, A method for producing a carrier core material for an electrophotographic developer that is further crushed, classified, and surface-oxidized, wherein the main calcination is performed at an oxygen concentration of 5% by volume or less. A method for producing a carrier core material is provided.

本発明の上記電子写真現像剤用キャリア芯材の製造方法において、上記再度粉砕、混合時にＦｅ化合物、Ｍｇ化合物、Ｔｉ化合物、Ｓｒ化合物、Ｍｎ化合物から選ばれる少なくとも１種の化合物を添加することが望ましい。   In the method for producing a carrier core material for an electrophotographic developer according to the present invention, at least one compound selected from an Fe compound, Mg compound, Ti compound, Sr compound, and Mn compound may be added during the pulverization and mixing again. desirable.

本発明は、上記製造方法で得られたキャリア芯材の表面を樹脂で被覆することを特徴とする電子写真現像剤用キャリアの製造方法を提供するものである。   The present invention provides a method for producing a carrier for an electrophotographic developer, wherein the surface of the carrier core obtained by the above production method is coated with a resin.

本発明は、上記キャリア又は上記製造方法により得られたキャリアとトナーからなる電子写真現像剤を提供するものである。   The present invention provides an electrophotographic developer comprising the above carrier or the carrier obtained by the above production method and a toner.

本発明に係る電子写真現像剤は、補給用現像剤としても用いられる。   The electrophotographic developer according to the present invention is also used as a replenishment developer.

本発明に係る電子写真現像剤用キャリア芯材は、各重金属のみならず、Ｍｎを必要以上に用いることなしに、高磁化でありながら中抵抗又は高抵抗といった所望の抵抗が得られ、かつ帯電特性に優れ、しかも適度な凹凸を有する表面性と揃った形状とを兼ね備える。そして、上記キャリア芯材に樹脂を被覆して得られるキャリアとトナーとからなる電子写真現像剤は、長寿命化が達成され、かつ高い帯電量を有し、帯電安定性にも優れる。また、本発明の製造方法によって、上記キャリア芯材及びキャリアが工業的規模をもって安定的に製造できる。   The carrier core material for an electrophotographic developer according to the present invention can obtain a desired resistance such as medium resistance or high resistance while being highly magnetized without using not only heavy metals but also Mn more than necessary. It has excellent characteristics and also has a surface shape with moderate irregularities and a uniform shape. An electrophotographic developer comprising a carrier and a toner obtained by coating the carrier core material with a resin has a long life, has a high charge amount, and is excellent in charging stability. Moreover, the carrier core material and the carrier can be stably produced on an industrial scale by the production method of the present invention.

以下、本発明を実施するための形態について説明する。   Hereinafter, modes for carrying out the present invention will be described.

＜本発明に係る電子写真現像剤用キャリア芯材及びキャリア＞
本発明に係る電子写真現像剤用キャリア芯材は、Ｍｇを０．８〜５重量％、好ましくは０．８〜４重量％、より好ましくは０．８〜３．８重量％、Ｔｉを０．１〜２．５重量％、好ましくは０．２〜２．５重量％、より好ましくは０．４〜２．５重量％、Ｆｅを６０〜７０重量％、好ましくは６０〜６８．５重量％、より好ましくは６０〜６７重量％、Ｓｒを０．２〜２．５重量％、好ましくは０．２〜２重量％、より好ましくは０．２２〜２重量％含有する。上記組成範囲において、高磁化でありながら中抵抗〜高抵抗が得られ、また電子写真現像剤用キャリアとして使用する際も帯電特性も安定しており良好である。 <Carrier Core Material and Carrier for Electrophotographic Developer According to the Present Invention>
In the carrier core material for an electrophotographic developer according to the present invention, Mg is 0.8 to 5% by weight, preferably 0.8 to 4% by weight, more preferably 0.8 to 3.8% by weight, and Ti is 0%. 0.1-2.5 wt%, preferably 0.2-2.5 wt%, more preferably 0.4-2.5 wt%, Fe 60-70 wt%, preferably 60-68.5 wt% %, More preferably 60 to 67% by weight, Sr 0.2 to 2.5% by weight, preferably 0.2 to 2% by weight, more preferably 0.22 to 2% by weight. Within the above composition range, medium resistance to high resistance can be obtained while being highly magnetized, and charging characteristics are stable and good when used as a carrier for an electrophotographic developer.

ＭｇはＭｇＯの電気陰性度がプラス側に偏っているためマイナストナーに対する相性はきわめて良く、ＭｇＯを含有するマグネシウムフェライトキャリアとフルカラー用のトナーで構成される帯電の立ち上がりが良い現像剤を得ることが出来る。   Mg has an excellent electronegativity of MgO on the positive side, so it has a very good compatibility with negative toners, and a developer having a good rise in charge composed of a magnesium ferrite carrier containing MgO and a full color toner can be obtained. I can do it.

ＴｉはＴｉＯ２として電気陰性度がややマイナス側に偏っているため本来であればマイナストナーとの相性は良くないが、２．５重量％よりも少ない範囲でＦｅとＴｉの化合物（酸化物）としてマイナストナー用キャリアを含有することで帯電性に関してはその影響を最小限にすることができる。 Since Ti is TiO 2 and its electronegativity is slightly biased to the minus side, it is originally not compatible with minus toner, but it is a compound of Fe and Ti (oxide) within a range of less than 2.5% by weight. As a negative toner carrier, the influence on the charging property can be minimized.

Ｆｅの含有量が６０重量％未満では、Ｍｇ及び／又はＴｉの添加量が相対的に増えることで非磁性成分及び／又は低磁化成分が増加し、所望の磁気特性が得られないことを意味しており、７０重量％を超えるとＭｇ及び／又はＴｉの添加効果は得られず実質的にＦｅ３Ｏ４と同等のキャリア芯材になってしまう。Ｍｇの含有量はＭｇ：２価のＦｅ＝１：１〜１：４付近が最も良い。Ｍｇの含有量が０．８重量％未満では、キャリア芯材におけるマグネシウムフェライト相の生成量が少なく、Ｆｅ３Ｏ４相の生成量が相対的に増加することで保磁力が増大し所望の磁気特性が得られなくなる可能性があり、Ｍｇの含有量が５重量％を超えるとキャリア芯材中にマグネシウムフェライトの生成量が増加し所望の磁気特性が得られなくなる可能性がある。Ｔｉの含有量が０．１重量％未満では、Ｔｉ含有による焼成温度を下げる効果が得られず所望の表面性の芯材粒子が得られない可能性があり、２．５重量％を超えると、ＦｅとＴｉの複合酸化物による非磁性相の影響が大きくなるため磁化が低くなりすぎ所望の磁気特性が得られなくなる可能性がある。２価のＦｅの存在量は粉末Ｘ線回折による結晶構造解析、もしくはＭｎの含有量が少なく、酸化還元滴定が可能な場合には過マンガン酸カリウムや重クロム酸カリウムによる酸化還元滴定で把握することが出来る。 If the Fe content is less than 60% by weight, it means that the nonmagnetic component and / or low magnetization component increases due to the relative increase in the addition amount of Mg and / or Ti, and the desired magnetic properties cannot be obtained. However, if it exceeds 70% by weight, the effect of adding Mg and / or Ti cannot be obtained, and the carrier core material is substantially equivalent to Fe 3 O 4 . The Mg content is best in the vicinity of Mg: divalent Fe = 1: 1 to 1: 4. If the Mg content is less than 0.8% by weight, the amount of magnesium ferrite phase produced in the carrier core material is small, and the amount of Fe 3 O 4 phase produced is relatively increased, so that the coercive force is increased and the desired magnetism is increased. The characteristics may not be obtained, and if the Mg content exceeds 5% by weight, the amount of magnesium ferrite produced in the carrier core material may increase, and the desired magnetic characteristics may not be obtained. If the Ti content is less than 0.1% by weight, the effect of lowering the firing temperature due to the Ti content may not be obtained, and core particles having a desired surface property may not be obtained. The influence of the nonmagnetic phase due to the composite oxide of Fe and Ti increases, so that the magnetization becomes too low and desired magnetic characteristics may not be obtained. The amount of divalent Fe can be determined by crystal structure analysis by powder X-ray diffraction or by redox titration with potassium permanganate or dichromate when Mn content is low and redox titration is possible. I can do it.

本発明に係る電子写真現像剤用キャリア芯材は、Ｓｒを０．２〜２．５重量％含有する。Ｓｒが０．２重量％未満の場合には、Ｓｒの添加効果が得られず本焼成時の酸素濃度の変化に伴うＦｅ２Ｏ３の生成による磁化の低下が大きくなりやすくなるので良くない。さらに、１次焼成及び本焼成時にＳｒが芯材粒子表面に移動する効果が得られないため、抵抗及び芯材の帯電量を上げる効果が期待できない。Ｓｒの含有量が２．５重量％を超えると、ハードフェライト化しはじめるため磁気ブラシ上で現像剤の流動性が急激に悪くなる恐れがある。 The carrier core material for an electrophotographic developer according to the present invention contains 0.2 to 2.5% by weight of Sr. If Sr is less than 0.2% by weight, the effect of adding Sr cannot be obtained, and the decrease in magnetization due to the formation of Fe 2 O 3 accompanying the change in oxygen concentration during the main firing tends to be large, which is not good. Further, since the effect of moving Sr to the surface of the core material particles during the primary firing and the main firing cannot be obtained, the effect of increasing the resistance and the charge amount of the core material cannot be expected. When the content of Sr exceeds 2.5% by weight, the fluidity of the developer on the magnetic brush may be abruptly deteriorated because it begins to hard ferrite.

なお、Ｓｒ及びＦｅを含有する酸化物の結晶構造としては、ＳｒＯ・６Ｆｅ２Ｏ３又はＳｒＦｅ１２Ｏ１９として表現されるストロンチウムフェライトがあり、本発明に係る電子写真現像用キャリア芯材に含有されていても良い。 The crystal structure of the oxide containing Sr and Fe includes strontium ferrite expressed as SrO.6Fe 2 O 3 or SrFe 12 O 19 and is contained in the carrier core material for electrophotographic development according to the present invention. May be.

本発明に係る電子写真現像剤用キャリア芯材は、表面酸化処理により表面被覆が形成されている電子写真現像剤用キャリア芯材であって、表面酸化処理前の芯材表面の粗さＲａ処理前に対する表面酸化処理後の芯材表面の粗さＲａ処理後の比（ａ）が、２．３≧Ｒａ処理後／Ｒａ処理前＞１である。この範囲であれば、Ｆｅ２Ｏ３を含有する表面被覆層が得られるため、所望の磁化と抵抗を同時に得ることができる。 The carrier core material for an electrophotographic developer according to the present invention is a carrier core material for an electrophotographic developer surface coating is formed by surface oxidation treatment, the roughness of the surface oxidation treatment before the core material surface R a the ratio of post roughness R a process of core material surface after the surface oxidation treatment for pre-processing (a) is, 2.3 ≧ R a processed / R a preprocessing> 1. Within this range, the surface coating layer containing Fe 2 O 3 is obtained, it is possible to obtain desired magnetization and resistance at the same time.

上記比（ａ）が１以下では、芯材の表面の凹凸がなくなることを意味しており、表面酸化処理では１以下となることはない。上記比（ａ）が２．３より大きい場合、表面酸化被覆層が必要以上に形成されていることを意味しており、所望の抵抗と磁化を同時に得られない可能性が高い。この表面粗さＲａは、ＪＩＳ Ｂ０６０１−２００１に規定される算術平均粗さを示し、平均線から絶対値偏差の平均値であり、下記のように測定される。   When the ratio (a) is 1 or less, it means that the irregularities on the surface of the core material are eliminated, and the surface oxidation treatment does not become 1 or less. When the ratio (a) is larger than 2.3, it means that the surface oxide coating layer is formed more than necessary, and there is a high possibility that desired resistance and magnetization cannot be obtained simultaneously. The surface roughness Ra indicates the arithmetic average roughness defined in JIS B0601-2001, and is an average value of absolute value deviation from the average line, and is measured as follows.

（芯材表面の粗さＲａ）
芯材表面粗さＲａはキーエンス社製レーザー顕微鏡ＶＫ−９５１０を用い、測定する際には、レンズ倍率１５０倍、光学ズーム３．０倍、測定ピッチを０．０１μｍ、カットオフフィルタλｓ＝２．５μｍ、λｆ＝０．０８ｍｍを設定して芯材表面の凹凸を測定した。得られた芯材粒子の表面形状のデータを用いて、キャリアは１０μｍ四方の範囲を指定し、芯材粒子を真球状とみなして球面から平面にデータ補正した上で、ＪＩＳ Ｂ０６０１−２００１に準じて算出した。 (Roughness Ra of the core material surface)
The surface roughness Ra of the core material is measured using a laser microscope VK-9510 manufactured by Keyence Corporation. When measuring, the lens magnification is 150 times, the optical zoom is 3.0 times, the measurement pitch is 0.01 μm, and the cutoff filter λs = 2. The irregularities on the surface of the core material were measured by setting 5 μm and λf = 0.08 mm. Using the data of the surface shape of the obtained core material particles, the carrier specifies a range of 10 μm square, the core particle is regarded as a true sphere, and the data is corrected from a spherical surface to a flat surface, and in accordance with JIS B0601-2001. Calculated.

本発明に係る電子写真現像剤用キャリア芯材は、Ｍｎを含有していてもよく、その含有量が好ましくは１０重量％以下、より好ましくは７重量％以下、最も好ましくは４重量％以下である。Ｍｎは、用途に応じて抵抗と磁化のバランスを改善させるため意図的に添加してもよい。この場合は特に本焼成における炉出の際の再酸化を防止する効果が期待できる。意図的添加でない場合においては、原料由来の不純物としてのＭｎの微量の含有は問題ない。添加するときのＭｎの形態は特に制限はないがＭｎＯ２、Ｍｎ２Ｏ３、Ｍｎ３Ｏ４、ＭｎＣＯ３が工業用途で入手しやすいので好ましい。 The carrier core material for an electrophotographic developer according to the present invention may contain Mn, and the content thereof is preferably 10% by weight or less, more preferably 7% by weight or less, and most preferably 4% by weight or less. is there. Mn may be intentionally added in order to improve the balance between resistance and magnetization depending on the application. In this case, in particular, an effect of preventing reoxidation at the time of exit from the furnace in the main firing can be expected. In the case where it is not intentionally added, there is no problem with the inclusion of a trace amount of Mn as an impurity derived from the raw material. The form of Mn when added is not particularly limited, but MnO 2 , Mn 2 O 3 , Mn 3 O 4 and MnCO 3 are preferable because they are easily available for industrial use.

（Ｆｅ、Ｍｇ、Ｔｉ、Ｓｒ及びＭｎの含有量）
これらＦｅ、Ｍｇ、Ｔｉ、Ｓｒ及びＭｎの含有量は、下記によって測定される。
キャリア芯材０．２ｇを秤量し、純水６０ｍｌに１Ｎの塩酸２０ｍｌ及び１Ｎの硝酸２０ｍｌを加えたものを加熱し、キャリア芯材を完全溶解させた水溶液を準備し、ＩＣＰ分析装置（島津製作所製ＩＣＰＳ−１０００ＩＶ）を用いてＦｅ、Ｍｇ、Ｔｉ、Ｓｒ及びＭｎの含有量を測定した。 (Contents of Fe, Mg, Ti, Sr and Mn)
The contents of these Fe, Mg, Ti, Sr and Mn are measured by the following.
0.2 g of carrier core material is weighed, 60 ml of pure water plus 20 ml of 1N hydrochloric acid and 20 ml of 1N nitric acid is heated to prepare an aqueous solution in which the carrier core material is completely dissolved, and an ICP analyzer (Shimadzu Corporation) The contents of Fe, Mg, Ti, Sr, and Mn were measured using ICPS-1000IV).

本発明に係る電子写真現像剤用キャリア芯材は、表面酸化処理後にＦｅ２Ｏ３成分が生成していることが望ましい。絶縁性の高いＦｅ２Ｏ３成分が生成することで抵抗が高くなる一方で、Ｆｅ２Ｏ３は磁化をほとんど持っていないのでＦｅ3Ｏ4の酸化によるＦｅ２Ｏ３を生成では高磁化と高抵抗を同時に満たすことは出来ない。しかしながら非磁性のＦｅＯからＦｅ２Ｏ３を直接生成させるか、Ｆｅ3Ｏ4経由で生成させることで磁化を大きく変動させることなく抵抗だけを高抵抗化することが出来る。 In the carrier core material for an electrophotographic developer according to the present invention, it is desirable that an Fe 2 O 3 component is generated after the surface oxidation treatment. The generation of the highly insulating Fe 2 O 3 component increases the resistance. On the other hand, since Fe 2 O 3 has almost no magnetization, the generation of Fe 2 O 3 by the oxidation of Fe 3 O 4 produces high magnetization. High resistance cannot be satisfied at the same time. However, by generating Fe 2 O 3 directly from nonmagnetic FeO or via Fe 3 O 4 , only the resistance can be increased without greatly changing the magnetization.

本発明でいうＦｅＯとは、ＦｅＯのみだけでなくＦｅとＯの比が０．８：１〜１：１のものを含むものとし、さらにＦｅの一部がＭｎ及び／又はＭｇに置換しているものをすべて含むものとする。なお、結晶構造の測定方法については後述する。   The term “FeO” as used in the present invention includes not only FeO but also Fe: O ratio of 0.8: 1 to 1: 1, and a part of Fe is substituted with Mn and / or Mg. All things are included. The crystal structure measurement method will be described later.

本発明に係る電子写真現像剤用キャリア芯材は、Ｍｇを含有するスピネル構造以外に少なくともＦｅ及びＴｉを含有する酸化物の結晶構造を含有する。Ｆｅ過剰のマグネシウム系フェライトにＴｉを添加することで通常のフェライトを構成するスピネル結晶構造の化合物以外に比較的磁化の低いＦｅ及びＴｉを含有する複合酸化物を必要とする磁化の範囲で生成させ、表面酸化処理時にスピネル相よりも優先的にＦｅ及びＴｉを含有する複合酸化物を酸化させることで磁化を変化させることなく抵抗のみを制御することが可能となる。つまり、Ｆｅ及びＴｉを含有する複合酸化物中に含まれるＦｅの価数が変化することで抵抗を調整している。結晶構造については、下記によって測定される。   The carrier core material for an electrophotographic developer according to the present invention contains an oxide crystal structure containing at least Fe and Ti in addition to the spinel structure containing Mg. By adding Ti to Fe-excess magnesium-based ferrite, in addition to the spinel crystal structure compound that constitutes normal ferrite, a composite oxide containing Fe and Ti with relatively low magnetization is generated in the required magnetization range. It is possible to control only the resistance without changing the magnetization by oxidizing the composite oxide containing Fe and Ti preferentially over the spinel phase during the surface oxidation treatment. That is, the resistance is adjusted by changing the valence of Fe contained in the composite oxide containing Fe and Ti. The crystal structure is measured by the following.

（結晶構造の測定：Ｘ線回折測定）
測定装置としてパナリティカル社製「Ｘ’ＰｅｒｔＰＲＯ ＭＰＤ」を用いた。Ｘ線源としてＣｏ管球（ＣｏＫα線）を、光学系として集中光学系及び高速検出器「Ｘ‘Ｃｅｌａｒａｔｏｒ」を用いて、測定は０．２°／ｓｅｃの連続スキャンで行った。測定結果は通常の粉末の結晶構造解析と同様に解析用ソフトウエア「Ｘ’Ｐｅｒｔ
ＨｉｇｈＳｃｏｒｅ」を用いてデータ処理し、結晶構造の同定し、得られた結晶構造を精密化することで体積換算の存在比率を算出した。存在比率の算出に際してマグネシウムフェライトとＦｅ３Ｏ４のピークの分離が難しいためスピネル相として取り扱い、それ以外の結晶構造はそれぞれの存在比率を算出した。なお、結晶構造の同定を行う際にＦｅ、Ｏを必須元素としＭｎ、Ｍｇ、Ｔｉ、Ｓｒは含有する可能性のある元素とした。また、Ｘ線源についてはＣｕ管球でも問題なく測定できるが、Ｆｅを多く含んだサンプルの場合には測定対象となるピークと比較してバックグラウンドが大きくなるので、Ｃｏ管球を用いる方が好ましい。また、光学系は平行法でも同様の結果が得られる可能性があるが、Ｘ線強度が低く測定に時間がかかるため集中光学系での測定が好ましい。さらに、連続スキャンの速度は特に制限はないが結晶構造の解析を行う際に十分なＳ／Ｎ比を得るためにスピネル構造の（１１３）面のピーク強度が約５００００ｃｐｓとなるようにし、粒子の特定の優先方向への配向がないようにサンプルセルにキャリア芯材をセットし測定を行った。 (Measurement of crystal structure: X-ray diffraction measurement)
“X′PertPRO MPD” manufactured by Panalical Co., Ltd. was used as a measuring apparatus. Measurement was performed by continuous scanning at 0.2 ° / sec using a Co tube (CoKα ray) as an X-ray source and a concentrated optical system and a high-speed detector “X'Celarator” as an optical system. The measurement result is the same as that of the usual crystal structure analysis of powder “X'Pert”
Data processing was performed using “HighScore”, the crystal structure was identified, and the obtained crystal structure was refined to calculate the volume ratio existence ratio. When calculating the abundance ratio, it was difficult to separate the peaks of magnesium ferrite and Fe 3 O 4 , so that it was treated as a spinel phase, and the abundance ratios of the other crystal structures were calculated. In identifying the crystal structure, Fe and O are essential elements, and Mn, Mg, Ti, and Sr are elements that may be contained. In addition, the X-ray source can be measured without problems even with a Cu tube, but in the case of a sample containing a large amount of Fe, the background becomes larger than the peak to be measured, so it is better to use a Co tube. preferable. In addition, the optical system may obtain the same result even when the parallel method is used, but measurement with a concentrated optical system is preferable because the X-ray intensity is low and measurement takes time. Furthermore, the speed of continuous scanning is not particularly limited, but in order to obtain a sufficient S / N ratio when analyzing the crystal structure, the peak intensity of the (113) plane of the spinel structure is set to about 50000 cps, The measurement was performed by setting the carrier core material in the sample cell so that there was no orientation in a specific preferred direction.

マグネシウムフェライトを構成するスピネル構造としてＭｇＦｅ２Ｏ４が代表的なものであるが、元素の構成比からもわかるようにＦｅ過剰であるためＭｇの一部がＦｅに置換され形式的にＭｇｘＦｅｙ−ｘＯ４、（ＭｇｘＦｅ１−ｘ）（Ｍｇｘ‘Ｆｅ１−ｘ’）２Ｏ４等で表現される結晶構造及びその一部がＭｎ、Ｔｉ及びＳｒのうち１種類以上の元素で置換されたものもすべて含まれるものとし、非酸化性雰囲気で焼成されることにより周期的にスピネル構造に格子欠陥が含まれるものも含むものとする。 MgFe 2 O 4 is a typical spinel structure that constitutes magnesium ferrite, but as can be seen from the composition ratio of the elements, Fe is excessive, so that part of Mg is replaced with Fe and formally Mg x Fe. y-x O 4, (Mg x Fe 1-x) (Mg x 'Fe 1-x') 2 O 4 crystal structure and a part thereof is expressed by the like Mn, 1 or more of Ti and Sr All elements substituted with elements are also included, and those in which lattice defects are periodically included in the spinel structure by firing in a non-oxidizing atmosphere are also included.

マグネシウムフェライトの代わりにＦｅ３Ｏ４がスピネル構造として測定されることがあるが、本発明で言うＦｅ３Ｏ４とはＦｅ３Ｏ４のみだけでなくＦｅとＯの比が２．５：４〜３：４のものを含むものとし、さらにＦｅの一部がＭｇとＭｎ、Ｔｉ及びＳｒのうち１種類以上の元素で置換しているものをすべて含むものとし、非酸化性雰囲気で焼成されることにより周期的にスピネル構造に格子欠陥が含まれるものも含むものとする。なお、結晶構造の測定方法については後述する。 Although Fe 3 O 4 may be measured as a spinel structure instead of magnesium ferrite, the term “Fe 3 O 4 ” used in the present invention is not only Fe 3 O 4 but also the ratio of Fe to O is 2.5: 4. ~ 3: 4 shall be included, and all Fe shall be replaced with one or more elements of Mg, Mn, Ti and Sr, and fired in a non-oxidizing atmosphere. Therefore, the spinel structure periodically includes a lattice defect. The crystal structure measurement method will be described later.

Ｆｅ及びＴｉを含有する酸化物の結晶構造としてスピネル構造以外ではＦｅＴｉＯ３、Ｆｅ２ＴｉＯ５が代表的である。Ｔｉと比べてＦｅが圧倒的に存在量としては多く、ＦｅｘＴｉＯｙ以外に（ＦｅＴｉＯ３）ｘ（Ｆｅ２Ｏ３）ｙ、Ｆｅ（ＦｅｘＴｉｙ）Ｏ４、（ＦｅｘＴｉ１−ｘ）（Ｆｅｘ‘Ｔｉ１−ｘ’）Ｏ４等で表現される結晶構造及びその一部がＭｎ／又はＳｒに置換されたもの、さらに非酸化性雰囲気で焼成されることにより周期的に上記結晶構造に格子欠陥が含まれるものも含むものとする。上記結晶構造以外にストロンチウムフェライトの前駆体であるＳｒ２Ｆｅ２Ｏ５の一部がＴｉ及び／又はＭｎに置換されたＳｒａＦｅｂＴｉｃＯｄ、ＳｒａＦｅｂＭｎｃＴｉｄＯｅ等で表わされる酸化物もすべて含まれるものとし、非酸化性雰囲気で焼成されることにより周期的に上記結晶構造に格子欠陥が含まれるものも含むものとする。 As the crystal structure of the oxide containing Fe and Ti, FeTiO 3 and Fe 2 TiO 5 are typical except for the spinel structure. Many as Fe is the amount present overwhelmingly as compared with Ti, in addition to Fe x TiO y (FeTiO 3) x (Fe 2 O 3) y, Fe (Fe x Ti y) O 4, (Fe x Ti 1- x) (Fe x 'Ti 1 -x') which O 4 crystal structure and a part thereof is expressed by the like is substituted with Mn / or Sr, periodically by being calcined in a non-oxidizing atmosphere The crystal structure includes those containing lattice defects. Some of Sr 2 Fe 2 O 5 which is a precursor of strontium ferrite in addition to the crystal structure is replaced by a Ti and / or Mn Sr a Fe b Ti c O d, Sr a Fe b Mn c Ti d O e All oxides represented by the above and the like are also included, and include those in which lattice defects are periodically included in the crystal structure by firing in a non-oxidizing atmosphere.

本発明に係る電子写真現像剤用キャリア芯材は、ＳｒのｐＨ４標準液による溶出が５０〜１０００ｐｐｍであることが必要である。好ましくは５０〜９００ｐｐｍ、より好ましくは５０〜８００ｐｐｍである。   The carrier core material for an electrophotographic developer according to the present invention is required to have an elution with Sr pH 4 standard solution of 50 to 1000 ppm. Preferably it is 50-900 ppm, More preferably, it is 50-800 ppm.

ＳｒのｐＨ４標準液による溶出が５０ｐｐｍよりも低い場合はＳｒを含有していないことを意味しており、Ｓｒの含有効果を期待できないことを意味している。１０００ｐｐｍよりも多い場合には芯材表面のＳｒ存在量が多すぎるため芯材が高抵抗になりすぎキャリア化した際に高抵抗によるキャリア飛散や画像欠陥が生じる原因となる。ＳｒのｐＨ４標準液による溶出量は下記により測定される。   When the elution by Sr pH 4 standard solution is lower than 50 ppm, it means that Sr is not contained, which means that the effect of containing Sr cannot be expected. When the amount is more than 1000 ppm, the amount of Sr present on the surface of the core material is too large, and the core material becomes too high in resistance, which causes carrier scattering and image defects due to high resistance. The elution amount of Sr with pH 4 standard solution is measured as follows.

（Ｓｒ溶出量）
キャリア芯材５０ｇとｐＨメーター校正用ｐＨ４標準液５０ｍｌを１００ｍｌガラスビンに入れ、ペイントシェーカーで１０分間攪拌した。攪拌終了後上澄み液を２ｍｌサンプリングし、純水を加えて１００ｍｌに希釈した溶液をＩＣＰにて測定し、得られた測定値を５０倍してＳｒ溶出量の値とした。なお、ｐＨ４標準液はＪＩＳ Ｚ ８８０２のｐＨ測定方法に指定されているものを使用した。 (Sr elution amount)
50 g of carrier core material and 50 ml of pH 4 standard solution for pH meter calibration were placed in a 100 ml glass bottle and stirred for 10 minutes with a paint shaker. After completion of the stirring, 2 ml of the supernatant was sampled, a solution diluted with pure water to 100 ml was measured with ICP, and the obtained measured value was multiplied by 50 to obtain the Sr elution value. The pH 4 standard solution used was specified in the pH measurement method of JIS Z 8802.

本発明に係る電子写真現像剤用キャリア芯材は、形状係数ＳＦ−２（真円度）が１００〜１２０であることが必要である。形状係数ＳＦ−２は、キャリアの投影周囲長を２乗した値をキャリアの投影面積で割った値に４πで除し、さらに１００倍して得られる数値であり、キャリアの形状が球に近いほど１００に近い値になる。キャリア芯材の形状係数ＳＦ−２が１２０を超えると芯材表面の凹凸が大きいことを意味し、樹脂がしみ込みやすくなるため電子写真用キャリアとして所望の特性が得られなくなる可能性がある。この形状係数ＳＦ−２（真円度）は、下記によって測定される。   The carrier core material for an electrophotographic developer according to the present invention needs to have a shape factor SF-2 (roundness) of 100 to 120. The shape factor SF-2 is a value obtained by dividing the value obtained by squaring the carrier projection perimeter length by the value obtained by dividing the value by the carrier projection area by 4π, and multiplying it by 100. The shape of the carrier is close to a sphere. The value becomes closer to 100. If the shape factor SF-2 of the carrier core material exceeds 120, it means that the surface of the core material has large irregularities, and the resin is likely to penetrate, so that desired characteristics as an electrophotographic carrier may not be obtained. This shape factor SF-2 (roundness) is measured by the following.

（形状係数ＳＦ−２（真円度））   (Shape factor SF-2 (roundness))

Figure 0005348588
Figure 0005348588

本発明に係る電子写真現像剤用キャリア芯材は、２ｍｍＧａｐ印加電圧５００Ｖにおける抵抗が、５×１０７〜１×１０９Ωであることが望ましい。電気抵抗が５×１０７Ω・ｃｍ未満では、抵抗が低すぎて帯電低下を引き起こす可能性がある。電気抵抗が１×１０９Ωを超えると、抵抗が高くなりすぎ、摩擦帯電に伴う電荷の移動が阻害される恐れがある。この電気抵抗は、下記によって測定される。 The carrier core material for an electrophotographic developer according to the present invention preferably has a resistance of 5 × 10 7 to 1 × 10 9 Ω at a 2 mm Gap applied voltage of 500 V. If the electric resistance is less than 5 × 10 7 Ω · cm, the resistance is too low, which may cause a decrease in charging. When the electric resistance exceeds 1 × 10 9 Ω, the resistance becomes too high, and there is a possibility that the movement of electric charge accompanying triboelectric charging is hindered. This electrical resistance is measured by:

（電気抵抗）
電極間間隔２．０ｍｍにて非磁性の平行平板電極（１０ｍｍ×４０ｍｍ）を対抗させ、その間に、試料２００ｍｇを秤量して充填する。磁石（表面磁束密度：１５００Ｇａｕｓｓ、電極に接する磁石の面積：１０ｍｍ×３０ｍｍ）を平行平板電極に付けることにより電極間に試料を保持させ、５００Ｖの電圧を印加し、５００Ｖの印加電圧における抵抗を絶縁抵抗計（ＳＭ−８２１０、東亜ディケーケー（株）製）にて測定した。なお、室温２５℃、湿度５５％に制御された恒温恒湿室内で測定を行った。 (Electrical resistance)
A non-magnetic parallel plate electrode (10 mm × 40 mm) is made to oppose with a distance between electrodes of 2.0 mm, and 200 mg of a sample is weighed and filled between them. A sample is held between the electrodes by attaching a magnet (surface magnetic flux density: 1500 Gauss, area of the magnet in contact with the electrode: 10 mm × 30 mm) to the parallel plate electrodes, a voltage of 500 V is applied, and resistance at an applied voltage of 500 V is insulated. The resistance was measured with a resistance meter (SM-8210, manufactured by Toa Decay Co., Ltd.). Note that the measurement was performed in a constant temperature and humidity room controlled at a room temperature of 25 ° C. and a humidity of 55%.

本発明に係る電子写真現像剤用キャリア芯材は、見掛け密度が２．３〜２．６ｇ／ｃｍ３であることが望ましく、この範囲では本発明に係る芯材を樹脂被覆し、キャリアとして使用した場合現像器中で十分攪拌することが出来るため帯電量の変動が少ないキャリアとして使用できる。見掛け密度２．３ｇ／ｃｍ３未満では、十分攪拌することが出来ないため帯電量の分布が広がってしまいかぶりの原因となる可能性がある。見掛け密度が２．６ｇ／ｃｍ３を超えることは本特許記載の組成ではない。この見掛け密度は、下記によって測定される。 The carrier core material for an electrophotographic developer according to the present invention preferably has an apparent density of 2.3 to 2.6 g / cm 3. In this range, the core material according to the present invention is coated with a resin and used as a carrier. In such a case, since it can be sufficiently stirred in the developing device, it can be used as a carrier with little fluctuation in charge amount. If the apparent density is less than 2.3 g / cm 3, the mixture cannot be sufficiently stirred, so that the distribution of the charge amount may spread and cause fogging. It is not the composition described in this patent that the apparent density exceeds 2.6 g / cm 3 . This apparent density is measured by:

（見掛け密度）
ＪＩＳ Ｚ ２５０４に準拠して測定した。詳細は次の通りである。
１．装置
粉末見掛密度計は漏斗、コップ、漏斗支持器、支持棒及び支持台から構成されるものを用いる。天秤は、秤量２００ｇで感量５０ｍｇのものを用いる。
２．測定方法
（１）試料は、少なくとも１５０ｇ以上とする。
（２）試料は孔径２．５＋０．２／−０ｍｍのオリフィスを持つ漏斗に注ぎ流れ出た試料が、コップ一杯になってあふれ出るまで流し込む。
（３）あふれ始めたら直ちに試料の流入をやめ、振動を与えないようにコップの上に盛り上がった試料をへらでコップの上端に沿って平らにかきとる。
（４）コップの側面を軽く叩いて、試料を沈ませコップの外側に付着した試料を除去して、コップ内の試料の重量を０．０５ｇの精度で秤量する。
３．計算
前項２−（４）で得られた測定値に０．０４を乗じた数値をＪＩＳ−Ｚ８４０１（数値の丸め方）によって小数点以下第２位に丸め、「ｇ／ｃｍ３」の単位の見掛け密度とする。 (Apparent density)
It measured based on JISZ2504. Details are as follows.
1. Apparatus The powder apparent density meter is composed of a funnel, a cup, a funnel support, a support bar and a support base. A balance with a weighing of 200 mg and a weighing of 50 mg is used.
2. Measuring method (1) The sample shall be at least 150 g or more.
(2) The sample is poured into a funnel having an orifice with a pore diameter of 2.5 + 0.2 / −0 mm, and poured until the sample that has flowed out fills the glass and overflows.
(3) Stop the inflow of the sample as soon as it begins to overflow, and scrape the sample raised on the cup flatly with a spatula along the top edge of the cup so as not to give vibration.
(4) Tap the side surface of the cup to sink the sample and remove the sample attached to the outside of the cup, and weigh the sample in the cup with an accuracy of 0.05 g.
3. Calculation The numerical value obtained by multiplying the measured value obtained in 2- (4) above by 0.04 is rounded to the second decimal place by JIS-Z8401 (how to round the numerical value), and the unit of “g / cm 3 ” appears. Density.

本発明に係る電子写真現像剤用キャリア芯材は、ＢＥＴ比表面積が０．０７５〜０．１５ｍ２／ｇである。ＢＥＴ比表面積が０．０７５ｍ２／ｇ未満では、芯材表面の凹凸が少ないため樹脂被覆後の樹脂のアンカー効果が得られず、電子写真用キャリアとして寿命が短くなる可能性があり、ＢＥＴ比表面積が０．１５ｍ２／ｇを超えると芯材表面の凹凸が大きく樹脂がしみ込みやすくなるため電子写真用キャリアとして所望の特性が得られなくなる可能性がある。このＢＥＴ比表面積は、下記により測定される。 The carrier core material for an electrophotographic developer according to the present invention has a BET specific surface area of 0.075 to 0.15 m 2 / g. When the BET specific surface area is less than 0.075 m 2 / g, since the core surface has few irregularities, the anchor effect of the resin after resin coating cannot be obtained, and the life as an electrophotographic carrier may be shortened. If the surface area exceeds 0.15 m 2 / g, the irregularities on the surface of the core material will be large and the resin will easily penetrate, so that there is a possibility that desired characteristics as an electrophotographic carrier cannot be obtained. This BET specific surface area is measured by the following.

（ＢＥＴ比表面積）
自動比表面積測定装置ＧＥＭＩＮＩ２３６０」（島津製作所社製）を用いて、吸着ガスであるＮ２を吸着させて測定したキャリア粒子のＮ２吸着量から求めることができる。なお、ここでは、このＮ２吸着量を測定する際に用いられる測定管は、測定前に、減圧状態にて５０℃で２時間の空焼きを行った。さらに、この測定管にキャリア粒子５ｇを充填し、減圧状態で３０℃の温度で２時間前処理を行った後に、２５℃下でＮ２ガスをそれぞれ吸着させてその吸着量を測定した。それらの吸着量は、吸着等温線を描き、ＢＥＴ式から算出される値である。 (BET specific surface area)
Using an automatic specific surface area measuring apparatus GEMINI 2360 (manufactured by Shimadzu Corp.), it can be determined from the N 2 adsorption amount of carrier particles measured by adsorbing N 2 as an adsorption gas. Here, the measurement tube used for measuring the N 2 adsorption amount was baked for 2 hours at 50 ° C. in a reduced pressure state before the measurement. Further, 5 g of carrier particles were filled in this measuring tube, and after pretreatment at a temperature of 30 ° C. for 2 hours under reduced pressure, N 2 gas was adsorbed at 25 ° C., and the amount of adsorption was measured. These adsorption amounts are values calculated from the BET equation by drawing an adsorption isotherm.

本発明に係る電子写真現像剤用キャリア芯材は、３Ｋ・１０００／４π・Ａ／ｍの磁場をかけたときの磁化が５０〜８５Ａｍ２／ｋｇであることが望ましい。上記３Ｋ・１０００／４π・Ａ／ｍにおける磁化が５０Ａｍ２／ｇ未満であると、飛散物磁化が悪化しキャリア付着による画像欠陥の原因となる可能性があり、８５Ａｍ２／ｇを超えると、磁気ブラシ上における現像剤の穂が硬くなりすぎ画質を劣化させる可能性がある。残留磁化は２〜１０Ａｍ２／ｋｇであることが望ましい。上記３Ｋ・１０００／４π・Ａ／ｍにおける残留磁化は本発明に係る組成において２Ａｍ２／ｋｇ未満にはならない。１０Ａｍ２／ｋｇを超えると現像器中での現像剤の流動性が悪化し、十分に現像剤を攪拌しトナーに摩擦帯電を与えることが出来なくなる。保磁力は本発明に係る組成において、１０〜８０ ３Ｋ・１０００／４π・Ａ／ｍであることが望ましい。本発明に係る組成においては、１０ ３Ｋ・１０００／４π・Ａ／ｍ未満にはならない。８０ ３Ｋ・１０００／４π・Ａ／ｍを超えると現像器中での現像剤の流動性が悪化し、十分に現像剤を攪拌しトナーに摩擦帯電を与えることが出来なくなる。磁化、残留磁化及び保磁力は、下記によって測定される。 The carrier core material for an electrophotographic developer according to the present invention preferably has a magnetization of 50 to 85 Am 2 / kg when a magnetic field of 3K · 1000 / 4π · A / m is applied. When the magnetization at 3K · 1000 / 4π · A / m is less than 50 Am 2 / g, the scattered matter magnetization may be deteriorated and cause image defects due to carrier adhesion. When the magnetization exceeds 85 Am 2 / g, There is a possibility that the ears of the developer on the brush become too hard and deteriorate the image quality. The residual magnetization is desirably 2 to 10 Am 2 / kg. The remanent magnetization at 3K · 1000 / 4π · A / m is not less than 2 Am 2 / kg in the composition according to the present invention. If it exceeds 10 Am 2 / kg, the fluidity of the developer in the developing device deteriorates, and it becomes impossible to sufficiently stir the developer and give the toner triboelectric charge. In the composition according to the present invention, the coercive force is desirably 10 to 80 3K · 1000 / 4π · A / m. In the composition according to the present invention, it is not less than 10 3 K · 1000 / 4π · A / m. If it exceeds 80 3K · 1000 / 4π · A / m, the fluidity of the developer in the developing device deteriorates, and the developer cannot be sufficiently stirred to give the toner triboelectric charge. Magnetization, remanent magnetization and coercivity are measured by:

（磁気特性）
積分型Ｂ−ＨトレーサーＢＨＵ−６０型（理研電子社製）を使用して測定した。電磁石間に磁場測定用Ｈコイル及び磁化測定用４πＩコイルを入れる。この場合、試料は４πＩコイルに入れる。電磁石の電流を変化させ磁場Ｈを変化させたＨコイル及び４πＩコイルの出力をそれぞれ積分し、Ｈ出力をＸ軸に、４πＩコイルの出力をＹ軸に、ヒステリシスループを記録紙に描く。ここで測定条件としては、試料充填量：約１ｇ、試料充填セル：内径７ｍｍφ±０．０２ｍｍ、高さ１０ｍｍ±０．１ｍｍ、４πＩコイル：巻数３０回にて測定した。 (Magnetic properties)
It measured using the integral type BH tracer BHU-60 type (made by Riken Denshi Co., Ltd.). A magnetic field measuring H coil and a magnetization measuring 4πI coil are placed between the electromagnets. In this case, the sample is placed in a 4πI coil. The outputs of the H coil and the 4πI coil whose magnetic field H is changed by changing the current of the electromagnet are respectively integrated, and the H output is drawn on the X axis, the output of the 4πI coil is drawn on the Y axis, and a hysteresis loop is drawn on the recording paper. As measurement conditions, sample filling amount: about 1 g, sample filling cell: inner diameter 7 mmφ ± 0.02 mm, height 10 mm ± 0.1 mm, 4πI coil: measured with 30 turns.

本発明に係る電子写真現像剤用キャリア芯材は、レーザー回折式粒度分布測定装置により測定される平均粒径が好ましくは１５〜１２０μｍ、より好ましくは１５〜８０μｍ、最も好ましくは１５〜６０μｍである。体積平均粒径が１５μｍ未満であると、キャリア付着が発生しやすくなるため好ましくない。体積平均粒径が１２０μｍを超えると、画質が劣化しやすくなり、好ましくない。この体積平均粒径は、下記によって測定される。   The carrier core material for an electrophotographic developer according to the present invention preferably has an average particle size measured by a laser diffraction particle size distribution measuring device of 15 to 120 μm, more preferably 15 to 80 μm, and most preferably 15 to 60 μm. . If the volume average particle size is less than 15 μm, carrier adhesion tends to occur, which is not preferable. If the volume average particle diameter exceeds 120 μm, the image quality tends to deteriorate, which is not preferable. This volume average particle size is measured by:

（体積平均粒径）
装置として日機装株式会社製マイクロトラック粒度分析計（Ｍｏｄｅｌ９３２０−Ｘ１００）を用いた。分散媒には水を用いた。 (Volume average particle size)
As a device, a Nikkiso Co., Ltd. Microtrac particle size analyzer (Model 9320-X100) was used. Water was used as the dispersion medium.

本発明に係る電子写真現像剤用キャリア芯材は、表面が酸化処理されていることが望ましい。この表面酸化処理によって形成される酸化処理被膜の厚さは、０．１ｎｍ〜５μｍであることが好ましい。０．１ｎｍ未満であると、酸化被膜層の効果が小さく、５μｍを超えると、明らかに磁化が低下したり、高抵抗になりすぎるため、現像能力が低下する等の不具合が発生し易くなる。また、必要に応じて、酸化処理の前に還元を行ってもよい。酸化皮膜の厚さは酸化皮膜が形成されていることが確認できる程度の高倍率のＳＥＭ写真、光学顕微鏡及びレーザー顕微鏡から測定することが出来る。なお、酸化皮膜は芯材表面に均一で形成されていても良いし、部分的に酸化皮膜形成されていても良い。   The surface of the carrier core material for an electrophotographic developer according to the present invention is desirably oxidized. The thickness of the oxidized film formed by this surface oxidation treatment is preferably 0.1 nm to 5 μm. If the thickness is less than 0.1 nm, the effect of the oxide film layer is small. If the thickness exceeds 5 μm, the magnetization is clearly lowered or the resistance becomes too high, so that problems such as a reduction in developing ability tend to occur. Moreover, you may reduce | restore before an oxidation process as needed. The thickness of the oxide film can be measured from a high-magnification SEM photograph, an optical microscope, and a laser microscope that can confirm that the oxide film is formed. The oxide film may be formed uniformly on the surface of the core material, or may be partially formed with an oxide film.

本発明に係る電子写真現像剤用キャリアは、上記キャリア芯材の表面が樹脂で被覆されている。   In the carrier for an electrophotographic developer according to the present invention, the surface of the carrier core material is coated with a resin.

本発明に係る電子写真現像剤用樹脂被覆キャリアは、樹脂被膜量が、キャリア芯材に対して０．１〜１０重量％が望ましい。被膜量が０．０１重量％未満ではキャリア表面に均一な被膜層を形成することが難しく、また１０重量％を超えるとキャリア同士の凝集が発生してしまい、歩留まり低下等の生産性の低下と共に、実機内での流動性あるいは帯電量等の現像剤特性変動の原因となる。   The resin-coated carrier for an electrophotographic developer according to the present invention desirably has a resin coating amount of 0.1 to 10% by weight with respect to the carrier core material. If the coating amount is less than 0.01% by weight, it is difficult to form a uniform coating layer on the surface of the carrier. If the coating amount exceeds 10% by weight, the carriers are aggregated with a decrease in productivity such as a decrease in yield. This causes fluctuations in developer characteristics such as fluidity or charge amount in the actual machine.

ここに用いられる被膜形成樹脂は、組み合わせるトナー、使用される環境等によって適宜選択できる。その種類は特に限定されないが、例えば、フッ素樹脂、アクリル樹脂、エポキシ樹脂、ポリアミド樹脂、ポリアミドイミド樹脂、ポリエステル樹脂、不飽和ポリエステル樹脂、尿素樹脂、メラミン樹脂、アルキッド樹脂、フェノール樹脂、フッ素アクリル樹脂、アクリル−スチレン樹脂、シリコーン樹脂、あるいはアクリル樹脂、ポリエステル樹脂、エポキシ樹脂、ポリアミド樹脂、ポリアミドイミド樹脂、アルキッド樹脂、ウレタン樹脂、フッ素樹脂等の各樹脂で変性した変性シリコーン樹脂等が挙げられる。本発明では、アクリル樹脂、シリコーン樹脂又は変性シリコーン樹脂が最も好ましく用いられる。   The film forming resin used here can be appropriately selected depending on the toner to be combined, the environment in which it is used, and the like. The type is not particularly limited, for example, fluorine resin, acrylic resin, epoxy resin, polyamide resin, polyamideimide resin, polyester resin, unsaturated polyester resin, urea resin, melamine resin, alkyd resin, phenol resin, fluorine acrylic resin, Examples thereof include acrylic-styrene resins, silicone resins, or modified silicone resins modified with resins such as acrylic resins, polyester resins, epoxy resins, polyamide resins, polyamideimide resins, alkyd resins, urethane resins, and fluororesins. In the present invention, acrylic resin, silicone resin or modified silicone resin is most preferably used.

またキャリアの電気抵抗や帯電量、帯電速度をコントロールすることを目的に、被膜形成樹脂中に導電性剤を添加することができる。導電性剤はそれ自身の持つ電気抵抗が低いことから、添加量が多すぎると急激な電荷リークを引き起こしやすい。従って、添加量としては、被膜形成樹脂の固形分に対し０．２５〜２０．０重量％であり、好ましくは０．５〜１５．０重量％、特に好ましくは１．０〜１０．０重量％である。導電性剤としては、導電性カーボンや酸化チタン、酸化スズ等の酸化物、各種の有機系導電剤が挙げられる。   A conductive agent can be added to the film-forming resin for the purpose of controlling the electrical resistance, charge amount, and charging speed of the carrier. Since the conductive agent itself has a low electric resistance, an excessive amount of the conductive agent tends to cause an abrupt charge leak. Accordingly, the addition amount is 0.25 to 20.0% by weight, preferably 0.5 to 15.0% by weight, particularly preferably 1.0 to 10.0% by weight, based on the solid content of the film-forming resin. %. Examples of the conductive agent include conductive carbon, oxides such as titanium oxide and tin oxide, and various organic conductive agents.

また、上記被膜形成樹脂中には、帯電制御剤を含有させることができる。帯電制御剤の例としては、トナー用に一般的に用いられる各種の帯電制御剤や、各種シランカップリング剤が挙げられる。これは被膜形成によって芯材露出面積を比較的小さくなるように制御した場合、帯電付与能力が低下することがあるが、各種の帯電制御剤やシランカップリング剤を添加することにより、コントロールできるためである。使用できる帯電制御剤やカップリング剤の種類は特に限定されないが、ニグロシン系染料、４級アンモニウム塩、有機金属錯体、含金属モノアゾ染料等の帯電制御剤、アミノシランカップリング剤やフッ素系シランカップリング剤等が好ましい。帯電量の測定方法は、上述の通りである。   In addition, the film forming resin can contain a charge control agent. Examples of the charge control agent include various charge control agents generally used for toners and various silane coupling agents. This is because, when the core material exposed area is controlled to be relatively small by film formation, the charge imparting ability may decrease, but it can be controlled by adding various charge control agents and silane coupling agents. It is. The types of charge control agents and coupling agents that can be used are not particularly limited, but charge control agents such as nigrosine dyes, quaternary ammonium salts, organometallic complexes, and metal-containing monoazo dyes, aminosilane coupling agents, and fluorine-based silane couplings. An agent or the like is preferable. The method for measuring the charge amount is as described above.

＜本発明に係る電子写真現像剤用キャリア芯材及びキャリアの製造方法＞
次に、本発明に係る電子写真現像剤用キャリア芯材及びキャリアの製造方法について説明する。 <Carrier Core Material for Electrophotographic Developer According to the Present Invention and Carrier Manufacturing Method>
Next, the carrier core material for an electrophotographic developer and the method for producing the carrier according to the present invention will be described.

本発明に係る電子写真現像剤用キャリア芯材の製造方法は、Ｆｅ、Ｔｉ、Ｍｇ及びＳｒの各化合物を粉砕、混合、仮焼を行った後、再度粉砕、混合、造粒し、得られた造粒物を１次焼成、本焼成し、さらに解砕、分級、表面酸化処理する。   The method for producing a carrier core material for an electrophotographic developer according to the present invention is obtained by grinding, mixing, and calcining each compound of Fe, Ti, Mg, and Sr, and then grinding, mixing, and granulating again. The granulated product is subjected to primary firing, main firing, and further pulverization, classification, and surface oxidation treatment.

Ｆｅ、Ｔｉ、Ｍｇ及びＳｒの各化合物を粉砕、混合、仮焼を行った後、再度粉砕、混合、造粒して造粒物を調製する方法は、特に制限はなく、従来公知の方法が採用することができ、乾式による方法を用いても湿式による方法を用いてもよい。原料としてＦｅ２Ｏ３とＴｉＯ２とＭｇ（ＯＨ）２及び／又はＭｇＣＯ３とＳｒＣＯ３を混合し、さらにカーボンブラック及び／又はバインダーを添加し、非酸化性雰囲気又は弱還元性雰囲気で仮焼成し、少なくとも２価のＦｅを含有するスピネル相及びＦｅとＴｉを含有する複合酸化物相が存在するフェライト前駆体の状態を生成しておくことが良く、さらにこの仮焼成においてＦｅＯが生成していても良い。仮焼後得られた仮焼物を再度粉砕、混合、造粒する。この、再度粉砕、混合時に、必要に応じてＦｅ化合物、Ｍｇ化合物、Ｔｉ化合物、Ｓｒ化合物、Ｍｎ化合物の少なくとも１種の化合物を追加の原料として添加してもよい。添加するときの各元素の化合物の形態は特に制限はないが、Ｆｅ化合物の場合はＦｅ２Ｏ３、Ｆｅ３Ｏ４、ＦｅＯ、Ｍｇ化合物の場合はＭｇＯ、Ｍｇ（ＯＨ）２、ＭｇＣＯ３、Ｔｉ化合物の場合はＴｉＯ２、ＦｅＴｉＯ３、Ｆｅ２ＴｉＯ５、Ｓｒ化合物の場合はＳｒＯ、ＳｒＣＯ３、ＳｒＴｉＯ３、Ｍｎ化合物の場合はＭｎＯ２、Ｍｎ２Ｏ３、Ｍｎ３Ｏ４、ＭｎＣＯ３が工業用途で入手しやすいので好ましい。従来の製造方法では本焼成時にＦｅ２Ｏ３からスピネル相を生成させるため結晶構造の変化にかなりのエネルギーが必要となるが、あらかじめＦｅ２Ｏ３とＴｉＯ２とＭｇ（ＯＨ）２及び／又はＭｇＣＯ３とＳｒＣＯ３を混合し、さらにカーボンブラック及び／又はバインダーを添加し仮焼成を行った場合には、本焼成において必要最小限の結晶構造の変化だけでフェライト化が終了するので低温焼成が可能となる。なお、バインダーとしてはポリビニルアルコールやポリビニルピロリドンを使うことが好ましい。 The method of preparing a granulated product by pulverizing, mixing, and calcining each compound of Fe, Ti, Mg, and Sr and then re-pulverizing, mixing, and granulating is not particularly limited. It is possible to employ a dry method or a wet method. Mixing Fe 2 O 3 and TiO 2 and Mg (OH) 2 and / or MgCO 3 and SrCO 3 as raw materials, adding carbon black and / or binder, and pre-baking in non-oxidizing atmosphere or weak reducing atmosphere It is preferable to generate a state of a ferrite precursor in which a spinel phase containing at least divalent Fe and a composite oxide phase containing Fe and Ti are present, and FeO is generated in this preliminary firing. May be. The calcined material obtained after the calcining is pulverized, mixed and granulated again. At the time of this pulverization and mixing again, if necessary, at least one compound of Fe compound, Mg compound, Ti compound, Sr compound and Mn compound may be added as an additional raw material. The form of the compound of each element when added is not particularly limited, but in the case of Fe compound, Fe 2 O 3 , Fe 3 O 4 , FeO, in the case of Mg compound, MgO, Mg (OH) 2 , MgCO 3 , In the case of Ti compound, TiO 2 , FeTiO 3 , Fe 2 TiO 5 , in the case of Sr compound, SrO, SrCO 3 , SrTiO 3 , in the case of Mn compound, MnO 2 , Mn 2 O 3 , Mn 3 O 4 , MnCO 3 It is preferable because it is easily available for industrial use. In the conventional manufacturing method, since a spinel phase is generated from Fe 2 O 3 at the time of main firing, considerable energy is required to change the crystal structure, but Fe 2 O 3 , TiO 2 , Mg (OH) 2 and / or When MgCO 3 and SrCO 3 are mixed and carbon black and / or a binder are added and pre-baking is performed, ferriteization is completed with only a necessary change in the crystal structure in the main baking, so low-temperature baking is performed. It becomes possible. In addition, it is preferable to use polyvinyl alcohol or polyvinylpyrrolidone as a binder.

本発明の製造方法では、得られた造粒物を１次焼成、本焼成する。１次焼成は、非酸化性雰囲気下、５００〜１１００℃で行われる。   In the production method of the present invention, the obtained granulated product is subjected to primary firing and main firing. The primary firing is performed at 500 to 1100 ° C. in a non-oxidizing atmosphere.

次に、１２８０℃以下で本焼成が行われる。本焼成はより結晶構造をしっかりしたものとし、表面酸化による磁化の低下を防止する効果が期待できる。１次焼成を行うことで本焼成において１次焼成を行わない場合と比較して低温で焼成できるため、凹凸を持った芯材粒子としやすくなるだけでなく、高い球形度を確保することが可能となる。   Next, the main baking is performed at 1280 ° C. or lower. The main firing has a more solid crystal structure, and an effect of preventing a decrease in magnetization due to surface oxidation can be expected. By performing the primary firing, it can be fired at a lower temperature in comparison with the case where the primary firing is not performed in the main firing, so that not only the core particles with irregularities are easily formed but also high sphericity can be secured. It becomes.

本発明の製造方法では、上述したように、予め本焼成前の芯材粒子の造粒物の時点で原料由来の結晶構造だけでなく、少なくとも２価のＦｅを含有するスピネル相及びＦｅとＴｉを含有する複合酸化物相を含有し、さらに非酸化性雰囲気下、５００〜１１００℃で１次焼成を行うことでＦｅ２Ｏ３を経由せずにフェライト化を促進することが出来るので、本焼成においても従来と比較して１２８０℃以下の低温焼成が可能となる。 In the production method of the present invention, as described above, not only the crystal structure derived from the raw material but also the spinel phase containing at least divalent Fe and Fe and Ti in advance at the time of granulation of the core material particles before the main firing. Since it contains a composite oxide phase containing selenium and is further subjected to primary firing at 500 to 1100 ° C. in a non-oxidizing atmosphere, ferritization can be promoted without passing through Fe 2 O 3. Also in firing, firing at a low temperature of 1280 ° C. or lower is possible as compared with the conventional case.

本発明の製造方法では、本焼成を酸素濃度が５体積％以下の雰囲気で行う。酸素濃度が５体積％を超える場合は、焼成物の磁化が低くなりすぎ、キャリア飛散の原因となるので好ましくない。高磁化のキャリア芯材を得るために、酸素濃度３体積％以下が好ましく、１体積％以下がさらに好ましい。   In the production method of the present invention, the main baking is performed in an atmosphere having an oxygen concentration of 5% by volume or less. When the oxygen concentration exceeds 5% by volume, the magnetization of the fired product becomes too low, which causes carrier scattering, which is not preferable. In order to obtain a highly magnetized carrier core material, the oxygen concentration is preferably 3% by volume or less, more preferably 1% by volume or less.

その後、回収し、乾燥、分級を行ってキャリア芯材を得る。分級方法としては、既存の風力分級、メッシュ濾過法、沈降法など用いて所望の粒径に粒度調整する。乾式回収を行う場合は、サイクロン等で回収することも可能である。   Thereafter, it is collected, dried and classified to obtain a carrier core material. As a classification method, the particle size is adjusted to a desired particle size using an existing air classification, mesh filtration method, sedimentation method, or the like. When dry collection is performed, it can also be collected with a cyclone or the like.

その後、必要に応じて、表面を低温加熱することで酸化被膜処理を施し、電気抵抗調整を行うことができる。酸化被膜処理は、一般的なロータリー式電気炉、バッチ式電気炉等を用い、例えば、３００〜８００℃で熱処理を行う。酸化皮膜を均一に芯材粒子に形成させるためにはロータリー式電気炉を用いることが好ましい。   Thereafter, if necessary, the surface can be heated at a low temperature to perform an oxide film treatment to adjust electric resistance. For the oxide film treatment, a general rotary electric furnace, batch electric furnace or the like is used, and for example, heat treatment is performed at 300 to 800 ° C. In order to uniformly form the oxide film on the core particles, it is preferable to use a rotary electric furnace.

本発明の電子写真現像剤用キャリアは、上記キャリア芯材の表面に、上記した樹脂を被覆し、樹脂被膜を形成する。被覆する方法としては、公知の方法、例えば刷毛塗り法、流動床によるスプレードライ方式、ロータリドライ方式、万能攪拌機による液浸乾燥法等により被覆することができる。被覆率を向上させるためには、流動床による方法が好ましい。   In the carrier for an electrophotographic developer of the present invention, the surface of the carrier core material is coated with the above resin to form a resin film. As a coating method, it can be coated by a known method such as a brush coating method, a spray drying method using a fluidized bed, a rotary drying method, an immersion drying method using a universal stirrer, or the like. In order to improve the coverage, a fluidized bed method is preferred.

樹脂をキャリア芯材に被覆後、焼き付けする場合には、外部加熱方式又は内部加熱方式のいずれでもよく、例えば固定式又は流動式電気炉、ロータリー式電気炉、バーナー炉でもよく、もしくはマイクロウェーブによる焼き付けでもよい。ＵＶ硬化樹脂を用いる場合は、ＵＶ加熱器を用いる。焼き付けの温度は使用する樹脂により異なるが、融点又はガラス転移点以上の温度は必要であり、熱硬化性樹脂又は縮合架橋型樹脂等では、充分硬化が進む温度まで上げる必要がある。   When the resin is coated on the carrier core and then baked, either an external heating method or an internal heating method may be used, for example, a fixed or fluid electric furnace, a rotary electric furnace, a burner furnace, or by microwave It can be burned. When a UV curable resin is used, a UV heater is used. Although the baking temperature varies depending on the resin to be used, a temperature equal to or higher than the melting point or the glass transition point is necessary. For a thermosetting resin or a condensation-crosslinking resin, it is necessary to raise the temperature to a point where the curing proceeds sufficiently.

＜本発明に係る電子写真用現像剤＞
次に、本発明に係る電子写真用現像剤について説明する。
本発明に係る電子写真現像剤は、上述した電子写真現像剤用キャリアとトナーとからなるものである。 <Electrophotographic developer according to the present invention>
Next, the electrophotographic developer according to the present invention will be described.
The electrophotographic developer according to the present invention comprises the above-described carrier for an electrophotographic developer and a toner.

本発明の電子写真現像剤を構成するトナー粒子には、粉砕法によって製造される粉砕トナー粒子と、重合法により製造される重合トナー粒子とがある。本発明ではいずれの方法により得られたトナー粒子も使用することができる。   The toner particles constituting the electrophotographic developer of the present invention include pulverized toner particles produced by a pulverization method and polymerized toner particles produced by a polymerization method. In the present invention, toner particles obtained by any method can be used.

粉砕トナー粒子は、例えば、結着樹脂、荷電制御剤、着色剤をヘンシェルミキサー等の混合機で充分に混合し、次いで、二軸押出機等で溶融混練し、冷却後、粉砕、分級し、外添剤を添加後、ミキサー等で混合することにより得ることができる。   The pulverized toner particles are, for example, a binder resin, a charge control agent, and a colorant are sufficiently mixed with a mixer such as a Henschel mixer, then melt-kneaded with a twin screw extruder or the like, cooled, pulverized, classified, After adding the external additive, it can be obtained by mixing with a mixer or the like.

粉砕トナー粒子を構成する結着樹脂としては特に限定されるものではないが、ポリスチレン、クロロポリスチレン、スチレン−クロロスチレン共重合体、スチレン−アクリル酸エステル共重合体、スチレン−メタクリル酸共重合体、更にはロジン変性マレイン酸樹脂、エポキシ樹脂、ポリエステル樹脂及びポリウレタン樹脂等を挙げることができる。これらは単独又は混合して用いられる。   The binder resin constituting the pulverized toner particles is not particularly limited, but polystyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, Furthermore, rosin modified maleic acid resin, epoxy resin, polyester resin, polyurethane resin and the like can be mentioned. These may be used alone or in combination.

荷電制御剤としては、任意のものを用いることができる。例えば正荷電性トナー用としては、ニグロシン系染料及び４級アンモニウム塩等を挙げることができ、また、負荷電性トナー用としては、含金属モノアゾ染料等を挙げることができる。   Any charge control agent can be used. For example, nigrosine dyes and quaternary ammonium salts can be used for positively charged toners, and metal-containing monoazo dyes can be used for negatively charged toners.

着色剤（色材）としては、従来より知られている染料、顔料が使用可能である。例えば、カーボンブラック、フタロシアニンブルー、パーマネントレッド、クロムイエロー、フタロシアニングリーン等を使用することができる。その他、トナーの流動性、耐凝集性向上のためのシリカ粉体、チタニア等のような外添剤をトナー粒子に応じて加えることができる。   As the colorant (coloring material), conventionally known dyes and pigments can be used. For example, carbon black, phthalocyanine blue, permanent red, chrome yellow, phthalocyanine green, etc. can be used. In addition, external additives such as silica powder and titania for improving the fluidity and aggregation resistance of the toner can be added according to the toner particles.

重合トナー粒子は、懸濁重合法、乳化重合法、乳化凝集法、エステル伸長重合法、相転乳化法といった公知の方法で製造されるトナー粒子である。このような重合法トナー粒子は、例えば、界面活性剤を用いて着色剤を水中に分散させた着色分散液と、重合性単量体、界面活性剤及び重合開始剤を水性媒体中で混合攪拌し、重合性単量体を水性媒体中に乳化分散させて、攪拌、混合しながら重合させた後、塩析剤を加えて重合体粒子を塩析させる。塩析によって得られた粒子を、濾過、洗浄、乾燥させることにより、重合トナー粒子を得ることができる。その後、必要により乾燥されたトナー粒子に機能付与のため外添剤を添加することもできる。   The polymerized toner particles are toner particles produced by a known method such as a suspension polymerization method, an emulsion polymerization method, an emulsion aggregation method, an ester elongation polymerization method, or a phase inversion emulsification method. Such polymerized toner particles are prepared by, for example, mixing and stirring a colored dispersion in which a colorant is dispersed in water using a surfactant, a polymerizable monomer, a surfactant, and a polymerization initiator in an aqueous medium. Then, the polymerizable monomer is emulsified and dispersed in an aqueous medium, polymerized while stirring and mixing, and then a salting-out agent is added to salt out the polymer particles. Polymerized toner particles can be obtained by filtering, washing and drying the particles obtained by salting out. Thereafter, if necessary, an external additive may be added to the dried toner particles to provide a function.

更に、この重合トナー粒子を製造するに際しては、重合性単量体、界面活性剤、重合開始剤、着色剤以外に、定着性改良剤、帯電制御剤を配合することができ、これらにより得られた重合トナー粒子の諸特性を制御、改善することができる。また、水性媒体への重合性単量体の分散性を改善するとともに、得られる重合体の分子量を調整するために連鎖移動剤を用いることができる。   Further, in the production of the polymerized toner particles, in addition to the polymerizable monomer, the surfactant, the polymerization initiator, and the colorant, a fixability improving agent and a charge control agent can be blended and obtained. Various characteristics of the polymerized toner particles can be controlled and improved. A chain transfer agent can be used to improve the dispersibility of the polymerizable monomer in the aqueous medium and adjust the molecular weight of the resulting polymer.

上記重合トナー粒子の製造に使用される重合性単量体に特に限定はないが、例えば、スチレン及びその誘導体、エチレン、プロピレン等のエチレン不飽和モノオレフィン類、塩化ビニル等のハロゲン化ビニル類、酢酸ビニル等のビニルエステル類、アクリル酸メチル、アクリル酸エチル、メタクリル酸メチル、メタクリル酸エチル、メタクリル酸２−エチルヘキシル、アクリル酸ジメチルアミノエステル及びメタクリル酸ジエチルアミノエステル等のα−メチレン脂肪族モノカルボン酸エステル類等を挙げることができる。   The polymerizable monomer used for the production of the polymerized toner particles is not particularly limited. For example, styrene and its derivatives, ethylene unsaturated monoolefins such as ethylene and propylene, vinyl halides such as vinyl chloride, Α-methylene aliphatic monocarboxylic acids such as vinyl esters such as vinyl acetate, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, 2-ethylhexyl methacrylate, dimethylamino acrylate and diethylaminoester methacrylate Examples include esters.

上記重合トナー粒子の調製の際に使用される着色剤（色材）としては、従来から知られている染料、顔料が使用可能である。例えば、カーボンブラック、フタロシアニンブルー、パーマネントレッド、クロムイエロー及びフタロシアニングリーン等を使用することができる。また、これらの着色剤はシランカップリング剤やチタンカップリング剤等を用いてその表面が改質されていてもよい。   Conventionally known dyes and pigments can be used as the colorant (coloring material) used in the preparation of the polymerized toner particles. For example, carbon black, phthalocyanine blue, permanent red, chrome yellow, phthalocyanine green, and the like can be used. Moreover, the surface of these colorants may be modified using a silane coupling agent, a titanium coupling agent, or the like.

上記重合トナー粒子の製造に使用される界面活性剤としては、アニオン系界面活性剤、カチオン系界面活性剤、両イオン性界面活性剤及びノニオン系界面活性剤を使用することができる。   As the surfactant used in the production of the polymerized toner particles, an anionic surfactant, a cationic surfactant, an amphoteric surfactant and a nonionic surfactant can be used.

ここで、アニオン系界面活性剤としては、オレイン酸ナトリウム、ヒマシ油等の脂肪酸塩、ラウリル硫酸ナトリウム、ラウリル硫酸アンモニウム等のアルキル硫酸エステル、ドデシルベンゼンスルホン酸ナトリウム等のアルキルベンゼンスルホン酸塩、アルキルナフタレンスルホン酸塩、アルキルリン酸エステル塩、ナフタレンスルホン酸ホルマリン縮合物、ポリオキシエチレンアルキル硫酸エステル塩等を挙げることができる。また、ノニオン性界面活性剤としては、ポリオキシエチレンアルキルエーテル、ポリオキシエチレン脂肪酸エステル、ソルビタン脂肪酸エステル、ポリオキシエチレンアルキルアミン、グリセリン、脂肪酸エステル、オキシエチレン−オキシプロピレンブロックポリマー等を挙げることができる。更に、カチオン系界面活性剤としては、ラウリルアミンアセテート等のアルキルアミン塩、ラウリルトリメチルアンモニウムクロライド、ステアリルトリメチルアンモニウムクロライド等の第４級アンモニウム塩等を挙げることができる。また、両イオン性界面活性剤としては、アミノカルボン酸塩、アルキルアミノ酸等を挙げることができる。   Here, examples of the anionic surfactant include fatty acid salts such as sodium oleate and castor oil, alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate, alkyl benzene sulfonates such as sodium dodecyl benzene sulfonate, and alkyl naphthalene sulfonic acids. Salt, alkyl phosphate ester salt, naphthalene sulfonic acid formalin condensate, polyoxyethylene alkyl sulfate ester salt and the like. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, glycerin, fatty acid ester, and oxyethylene-oxypropylene block polymer. . Furthermore, examples of the cationic surfactant include alkylamine salts such as laurylamine acetate, and quaternary ammonium salts such as lauryltrimethylammonium chloride and stearyltrimethylammonium chloride. Examples of amphoteric surfactants include aminocarboxylates and alkylamino acids.

上記のような界面活性剤は、重合性単量体に対して、通常は０．０１〜１０重量％の範囲内の量で使用することができる。このような界面活性剤は、単量体の分散安定性に影響を与えるとともに、得られた重合トナー粒子の環境依存性にも影響を及ぼす。上記範囲内の量で使用することは単量体の分散安定性の確保と重合トナー粒子の環境依存性を低減する観点から好ましい。   The surfactant as described above can be used usually in an amount in the range of 0.01 to 10% by weight with respect to the polymerizable monomer. Such a surfactant affects the dispersion stability of the monomer and also affects the environmental dependency of the obtained polymerized toner particles. Use in an amount within the above range is preferable from the viewpoint of ensuring the dispersion stability of the monomer and reducing the environmental dependency of the polymerized toner particles.

重合トナー粒子の製造には、通常は重合開始剤を使用する。重合開始剤には、水溶性重合開始剤と油溶性重合開始剤とがあり、本発明ではいずれをも使用することができる。本発明で使用することができる水溶性重合開始剤としては、例えば、過硫酸カリウム、過硫酸アンモニウム等の過硫酸塩、水溶性パーオキサイド化合物を挙げることができ、また、油溶性重合開始剤としては、例えば、アゾビスイソブチロニトリル等のアゾ系化合物、油溶性パーオキサイド化合物を挙げることができる。   For the production of polymerized toner particles, a polymerization initiator is usually used. The polymerization initiator includes a water-soluble polymerization initiator and an oil-soluble polymerization initiator, and any of them can be used in the present invention. Examples of the water-soluble polymerization initiator that can be used in the present invention include persulfates such as potassium persulfate and ammonium persulfate, water-soluble peroxide compounds, and oil-soluble polymerization initiators. Examples thereof include azo compounds such as azobisisobutyronitrile and oil-soluble peroxide compounds.

また、本発明において連鎖移動剤を使用する場合には、この連鎖移動剤としては、例えば、オクチルメルカプタン、ドデシルメルカプタン、ｔｅｒｔ−ドデシルメルカプタン等のメルカプタン類、四臭化炭素等を挙げることができる。   When a chain transfer agent is used in the present invention, examples of the chain transfer agent include mercaptans such as octyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, carbon tetrabromide, and the like.

更に、本発明で使用する重合トナー粒子が、定着性改善剤を含む場合、この定着性改良剤としては、カルナバワックス等の天然ワックス、ポリプロピレン、ポリエチレン等のオレフィン系ワックス等を使用することができる。   Further, when the polymerized toner particles used in the present invention contain a fixability improver, a natural wax such as carnauba wax, an olefin wax such as polypropylene or polyethylene can be used as the fixability improver. .

また、本発明で使用する重合トナー粒子が、帯電制御剤を含有する場合、使用する帯電制御剤に特に制限はなく、ニグロシン系染料、４級アンモニウム塩、有機金属錯体、含金属モノアゾ染料等を使用することができる。   Further, when the polymerized toner particles used in the present invention contain a charge control agent, the charge control agent to be used is not particularly limited, and nigrosine dyes, quaternary ammonium salts, organometallic complexes, metal-containing monoazo dyes, etc. Can be used.

また、重合トナー粒子の流動性向上等のために使用される外添剤としては、シリカ、酸化チタン、チタン酸バリウム、フッ素樹脂微粒子、アクリル樹脂微粒子等を挙げることができ、これらは単独であるいは組み合わせて使用することができる。   Examples of the external additive used for improving the fluidity of polymerized toner particles include silica, titanium oxide, barium titanate, fluororesin fine particles, and acrylic resin fine particles. Can be used in combination.

更に、水性媒体から重合粒子を分離するために使用される塩析剤としては、硫酸マグネシウム、硫酸アルミニウム、塩化バリウム、塩化マグネシウム、塩化カルシウム、塩化ナトリウム等の金属塩を挙げることができる。   Furthermore, examples of the salting-out agent used for separating the polymer particles from the aqueous medium include metal salts such as magnesium sulfate, aluminum sulfate, barium chloride, magnesium chloride, calcium chloride, and sodium chloride.

上記のようにして製造されたトナー粒子の体積平均粒径は、２〜１５μｍ、好ましくは３〜１０μｍの範囲内にあり、重合トナー粒子の方が粉砕トナー粒子よりも、粒子の均一性が高い。トナー粒子が２μｍよりも小さくなると、帯電能力が低下しかぶりやトナー飛散を引き起こしやすく、１５μｍを超えると、画質が劣化する原因となる。   The volume average particle size of the toner particles produced as described above is in the range of 2 to 15 μm, preferably 3 to 10 μm, and the polymerized toner particles have higher particle uniformity than the pulverized toner particles. . If the toner particles are smaller than 2 μm, the charging ability is lowered, and it is easy to cause fogging and toner scattering, and if it exceeds 15 μm, the image quality is deteriorated.

上記のように製造されたキャリアとトナーとを混合し、電子写真現像剤を得ることができる。キャリアとトナーの混合比、即ちトナー濃度は、３〜１５重量％に設定することが好ましい。３重量％未満であると所望の画像濃度が得にくく、１５重量％を超えると、トナー飛散やかぶりが発生しやすくなる。   An electrophotographic developer can be obtained by mixing the carrier and toner manufactured as described above. The mixing ratio of the carrier and the toner, that is, the toner concentration is preferably set to 3 to 15% by weight. If it is less than 3% by weight, it is difficult to obtain a desired image density. If it exceeds 15% by weight, toner scattering and fogging are likely to occur.

本発明に係る電子写真現像剤は、補給用現像剤として用いることもできる。この際のキャリアとトナーの混合比、即ちトナー濃度は１００〜３０００重量％に設定することが好ましい。   The electrophotographic developer according to the present invention can also be used as a replenishment developer. At this time, the mixing ratio of the carrier and the toner, that is, the toner concentration is preferably set to 100 to 3000% by weight.

上記のように調製された本発明に係る電子写真現像剤は、有機光導電体層を有する潜像保持体に形成されている静電潜像を、バイアス電界を付与しながら、トナー及びキャリアを有する二成分現像剤の磁気ブラシによって反転現像する現像方式を用いたデジタル方式のコピー機、プリンター、ＦＡＸ、印刷機等に使用することができる。また、磁気ブラシから静電潜像側に現像バイアスを印加する際に、ＤＣバイアスにＡＣバイアスを重畳する方法である交番電界を用いるフルカラー機等にも適用可能である。   The electrophotographic developer according to the present invention prepared as described above uses an electrostatic latent image formed on a latent image holding member having an organic photoconductor layer, while applying a bias electric field to the toner and the carrier. The present invention can be used in digital copiers, printers, fax machines, printers, and the like that use a developing method in which reversal development is performed using a two-component developer magnetic brush. Further, the present invention can also be applied to a full color machine using an alternating electric field, which is a method of superimposing an AC bias on a DC bias when a developing bias is applied from the magnetic brush to the electrostatic latent image side.

以下、実施例等に基づき本発明を具体的に説明する。   Hereinafter, the present invention will be specifically described based on examples and the like.

Ｆｅを３.１９４モル、Ｍｇを０．４モル、Ｔｉを０．１モル、Ｓｒを０．０２モルとなるようにＦｅ２Ｏ３、Ｍｇ（ＯＨ）２、ＴｉＯ２、ＳｒＣＯ３を秤量し、ローラーコンパクターでペレット化した。このとき、焼成を促進させる目的と３価のＦｅを還元させるため木炭を０．５ｗｔ％添加し、得られたペレットを１０３０℃にて非酸化性雰囲気でロータリー式の焼成炉で仮焼成し、有機物とガスの成分を除去しながらフェライト化を進めると同時に酸化鉄の一部を還元した。 Fe 2 O 3 , Mg (OH) 2 , TiO 2 , and SrCO 3 were weighed so that Fe was 3.194 mol, Mg was 0.4 mol, Ti was 0.1 mol, and Sr was 0.02 mol. And pelletized with a roller compactor. At this time, 0.5 wt% of charcoal was added for the purpose of promoting firing and reducing trivalent Fe, and the obtained pellets were temporarily fired in a rotary firing furnace at 1030 ° C. in a non-oxidizing atmosphere, While removing the organic matter and gas components, the ferritization was advanced and at the same time a part of the iron oxide was reduced.

得られた仮焼成物をビーズミルにて粉砕した。このとき、最終的な組成がＦｅ３.４７４モル、Ｍｇ０．４モル、Ｔｉ０．２５モル、Ｓｒ０．０５モル、Ｍｎを０．１モルとなるようにＦｅ２Ｏ３、Ｍｇ（ＯＨ）２、ＴｉＯ２、ＳｒＣＯ３、Ｍｎ３Ｏ４を秤量し添加した。また、粉砕の際、バインダー成分としてＰＶＡをスラリーに含まれる固形分の０．１５重量％となるように添加し、ポリカルボン酸系分散剤をスラリーの粘度が２〜３ポイズになるように添加し、スラリー粒径のＤ５０が２．３３５μｍであった。得られた粉砕スラリーをスプレードライヤーにて再度造粒し、１０３０℃にて非酸化性雰囲気でロータリー式の焼成炉で１次焼成を行い、有機物を除去しながらフェライト化を進めると同時に酸化鉄の一部を還元した。この一次焼成においては、木炭を０.５ｗｔ％添加した。 The obtained calcined product was pulverized with a bead mill. At this time, Fe 2 O 3 , Mg (OH) 2 , TiO so that the final composition is Fe 3.474 mol, Mg 0.4 mol, Ti 0.25 mol, Sr 0.05 mol, and Mn 0.1 mol. 2 , SrCO 3 and Mn 3 O 4 were weighed and added. Also, during grinding, PVA is added as a binder component so that the solid content in the slurry is 0.15% by weight, and a polycarboxylic acid-based dispersant is added so that the viscosity of the slurry is 2 to 3 poise. The slurry particle size D 50 was 2.335 μm. The obtained pulverized slurry is granulated again with a spray dryer, subjected to primary firing in a rotary firing furnace at 1030 ° C. in a non-oxidizing atmosphere, and proceeds with ferritization while removing organic substances. A part was reduced. In this primary firing, 0.5 wt% of charcoal was added.

１次焼成したものを８０メッシュの篩を使って粗大粒子を除去した後１２００℃、酸素濃度０．０５容量％以下の条件で１６時間焼成し焼成物を得た。得られた焼成物を解砕、分級、磁力選鉱を行い、キャリア芯材粒子を得た。このキャリア芯材粒子の磁化は７４Ａｍ２／ｋｇであった。得られたキャリア芯材粒子の結晶構造をＸ線回折装置にて確認したところＭｇを含有するスピネル結晶構造のほかにＦｅＯ（ウスタイト）及びＦｅとＴｉを含有する酸化物の結晶構造が確認された。 After the primary firing, coarse particles were removed using an 80-mesh sieve and then fired for 16 hours at 1200 ° C. and an oxygen concentration of 0.05 vol% or less to obtain a fired product. The obtained fired product was crushed, classified, and magnetically separated to obtain carrier core particles. The magnetization of the carrier core particles was 74 Am 2 / kg. The crystal structure of the obtained carrier core particles was confirmed by an X-ray diffractometer. In addition to the spinel crystal structure containing Mg, the crystal structure of FeO (wustite) and an oxide containing Fe and Ti was confirmed. .

さらに得られたキャリア芯材粒子を表面酸化処理温度６８０℃、大気雰囲気の条件の元、ロータリー式の電気炉で表面酸化処理を行い表面酸化処理済みのキャリア芯材粒子を得た。この表面酸化処理を行ったキャリア芯材粒子の体積平均粒径は３５．１５μｍ、磁化は６７Ａｍ２／ｋｇであった。 Further, the obtained carrier core particles were subjected to a surface oxidation treatment in a rotary electric furnace under the conditions of a surface oxidation treatment temperature of 680 ° C. and an atmospheric atmosphere to obtain surface oxidized carrier core particles. The carrier core particles subjected to the surface oxidation treatment had a volume average particle size of 35.15 μm and a magnetization of 67 Am 2 / kg.

原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３５．３１μｍのキャリア芯材粒子を得た。   The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core material particles having a volume average particle diameter of 35.31 μm were obtained.

原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３６．１０μｍのキャリア芯材粒子を得た。   The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle size of 36.10 μm were obtained.

原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３４．３９μｍのキャリア芯材粒子を得た。   The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle diameter of 34.39 μm were obtained.

原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３６．４８μｍのキャリア芯材粒子を得た。   The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core material particles having a volume average particle diameter of 36.48 μm were obtained.

原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３６．１５μｍのキャリア芯材粒子を得た。   The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle size of 36.15 μm were obtained.

仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３５．５２μｍのキャリア芯材粒子を得た。   Carrier core material particles having a volume average particle diameter of 35.52 μm were obtained in the same manner as in Example 1 except that the pre-calcined raw material and raw raw material were granulated at the ratio shown in Table 2.

仮焼済み原料及び生原料を表２に示す割合で本造粒し、一次焼成を９８０℃で行った以外は、実施例１と同様にして体積平均粒径が３６．４２μｍのキャリア芯材粒子を得た。   Carrier core particles having a volume average particle size of 36.42 μm as in Example 1, except that the pre-calcined raw material and raw material are granulated at a ratio shown in Table 2 and primary firing is performed at 980 ° C. Got.

仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３５．７０μｍのキャリア芯材粒子を得た。   Carrier core particles having a volume average particle size of 35.70 μm were obtained in the same manner as in Example 1 except that the pre-calcined raw material and raw raw material were granulated at the ratio shown in Table 2.

表面酸化処理温度を７００℃とした以外は、実施例１と同様にして体積平均粒径が３４．７１μｍのキャリア芯材粒子を得た。   Carrier core particles having a volume average particle size of 34.71 μm were obtained in the same manner as in Example 1 except that the surface oxidation treatment temperature was 700 ° C.

表面酸化処理温度を５５０℃とした以外は、実施例１と同様にして体積平均粒径が３４．９２μｍのキャリア芯材粒子を得た。   Carrier core material particles having a volume average particle diameter of 34.92 μm were obtained in the same manner as in Example 1 except that the surface oxidation treatment temperature was 550 ° C.

本焼成温度を１２４０℃とした以外は、実施例１と同様にして体積平均粒径が３５．８１μｍのキャリア芯材粒子を得た。   Carrier core particles having a volume average particle size of 35.81 μm were obtained in the same manner as in Example 1 except that the main firing temperature was 1240 ° C.

本焼成温度を１１６０℃とした以外は、実施例１と同様にして体積平均粒径が３４．８９μｍのキャリア芯材粒子を得た。   Carrier core particles having a volume average particle size of 34.89 μm were obtained in the same manner as in Example 1 except that the main firing temperature was 1160 ° C.

仮焼雰囲気を酸素濃度５０００ｐｐｍの条件とした以外は、実施例１と同様にして体積平均粒径が３５．４１μｍのキャリア芯材粒子を得た。   Carrier core material particles having a volume average particle size of 35.41 μm were obtained in the same manner as in Example 1 except that the calcining atmosphere was set to the condition of an oxygen concentration of 5000 ppm.

一次焼成雰囲気を酸素濃度８００ｐｐｍの条件とした以外は、実施例１と同様にして体積平均粒径が３６．４８μｍのキャリア芯材粒子を得た。   Carrier core material particles having a volume average particle size of 36.48 μm were obtained in the same manner as in Example 1 except that the primary firing atmosphere was set at a condition of oxygen concentration of 800 ppm.

比較例Comparative example

（比較例１）
原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３４．７３μｍのキャリア芯材粒子を得た。 (Comparative Example 1)
The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle diameter of 34.73 μm were obtained.

（比較例２）
原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３５．２９μｍのキャリア芯材粒子を得た。 (Comparative Example 2)
The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle size of 35.29 μm were obtained.

（比較例３）
原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３６．１４μｍのキャリア芯材粒子を得た。 (Comparative Example 3)
The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle size of 36.14 μm were obtained.

（比較例４）
仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３４．６４μｍのキャリア芯材粒子を得た。 (Comparative Example 4)
Carrier core material particles having a volume average particle diameter of 34.64 μm were obtained in the same manner as in Example 1 except that the pre-calcined raw material and raw raw material were granulated at the ratio shown in Table 2.

（比較例５）
原料を表１に示されるような割合で混合及びペレット化した後、仮焼し、仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３５．４８μｍのキャリア芯材粒子を得た。 (Comparative Example 5)
The raw materials were mixed and pelletized at the ratios shown in Table 1, then calcined, and the raw calcined raw materials and raw materials were granulated at the ratios shown in Table 2 in the same manner as in Example 1. Carrier core particles having a volume average particle size of 35.48 μm were obtained.

（比較例６）
仮焼済み原料及び生原料を表２に示す割合で本造粒した以外は、実施例１と同様にして体積平均粒径が３４．８７μｍのキャリア芯材粒子を得た。 (Comparative Example 6)
Carrier core material particles having a volume average particle diameter of 34.87 μm were obtained in the same manner as in Example 1 except that the pre-calcined raw material and raw raw material were granulated at the ratio shown in Table 2.

（比較例７）
仮焼済み原料及び生原料を表２に示す割合で本造粒し、一次焼成を９８０℃で行った以外は、実施例１と同様にして体積平均粒径が３６．１１μｍのキャリア芯材粒子を得た。 (Comparative Example 7)
Carrier core particles having a volume average particle size of 36.11 μm as in Example 1 except that the pre-calcined raw material and raw material are granulated at the ratio shown in Table 2 and primary firing is performed at 980 ° C. Got.

（比較例８）
表面酸化処理温度を１０００℃とした以外は、実施例１と同様にして体積平均粒径が３５．８１μｍのキャリア芯材粒子を得た。 (Comparative Example 8)
Carrier core particles having a volume average particle size of 35.81 μm were obtained in the same manner as in Example 1 except that the surface oxidation treatment temperature was 1000 ° C.

（比較例９）
表面酸化処理温度を２００℃とした以外は、実施例１と同様にして体積平均粒径が３４．６８μｍのキャリア芯材粒子を得た。 (Comparative Example 9)
Carrier core material particles having a volume average particle size of 34.68 μm were obtained in the same manner as in Example 1 except that the surface oxidation treatment temperature was 200 ° C.

（比較例１０）
本焼成温度を１３００℃とした以外は、実施例１と同様にして体積平均粒径が３４．３３μｍのキャリア芯材粒子を得た。 (Comparative Example 10)
Carrier core material particles having a volume average particle diameter of 34.33 μm were obtained in the same manner as in Example 1 except that the main firing temperature was 1300 ° C.

（比較例１１）
本焼成温度を１１００℃とした以外は、実施例１と同様にして体積平均粒径が３５．５３μｍのキャリア芯材粒子を得た。 (Comparative Example 11)
Carrier core material particles having a volume average particle size of 35.53 μm were obtained in the same manner as in Example 1 except that the main firing temperature was 1100 ° C.

（比較例１２）
本焼成の雰囲気を酸素濃度２.５ｖｏｌ％の条件とした以外は、実施例１と同様にして体積平均粒径が３６．７２μｍのキャリア芯材粒子を得た。 (Comparative Example 12)
Carrier core material particles having a volume average particle size of 36.72 μm were obtained in the same manner as in Example 1 except that the atmosphere of the main firing was made to have an oxygen concentration of 2.5 vol%.

実施例１〜１５及び比較例１〜１２について、表１にキャリア芯材の仮造粒条件及び仮焼条件、表２にキャリア芯材の本造粒条件、表３に本造粒後の最終的な組成比をそれぞれ示す。また、表４に一次焼成条件、本焼成条件及び表面酸化処理条件、表５に本焼成後の組成、表６に本焼成後と表面酸化処理後のＸ線回折による結晶構造解析結果をそれぞれ示す。さらに、表７に酸化処理前後の表面粗さ、酸化処理後の抵抗、酸化処理後のＳｒ溶出、酸化処理後の見掛け密度、酸化処理前後のＢＥＴ比表面積をそれぞれ示す。表８に酸化処理前後の磁化、酸化処理後の平均粒径、酸化処理後のＳＦ−２をそれぞれ示す。これらの測定方法は上述の通りである。   Regarding Examples 1 to 15 and Comparative Examples 1 to 12, Table 1 shows the provisional granulation conditions and calcining conditions for the carrier core, Table 2 shows the main granulation conditions for the carrier core, and Table 3 shows the final result after the main granulation. The respective composition ratios are shown. Table 4 shows the primary firing conditions, main firing conditions and surface oxidation treatment conditions, Table 5 shows the composition after the main firing, and Table 6 shows the results of crystal structure analysis by X-ray diffraction after the main firing and after the surface oxidation treatment. . Further, Table 7 shows the surface roughness before and after the oxidation treatment, the resistance after the oxidation treatment, the Sr elution after the oxidation treatment, the apparent density after the oxidation treatment, and the BET specific surface area before and after the oxidation treatment. Table 8 shows the magnetization before and after the oxidation treatment, the average particle diameter after the oxidation treatment, and SF-2 after the oxidation treatment. These measurement methods are as described above.

Figure 0005348588
Figure 0005348588

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Figure 0005348588

表１〜表８の結果から明らかなように、実施例1〜１５においては電子写真用キャリアとして使用する際に十分な特性値が得られることが確認された。一方、比較例１、３及び５は抵抗が低すぎ、比較例２、４、６及び７は抵抗が高すぎ電子写真キャリア用芯材として使用できないものとなった。また、比較例８はストロンチウムフェライトが部分的に生成し形状が悪くなった。比較例９は表面酸化処理の効果がなく抵抗が低くなりすぎる結果となった。比較例１０は過焼成となり形状が悪くなった。比較例１１は表面に細孔が発生し、樹脂被覆に適さない電子写真キャリア用芯材となった。比較例１２はストロンチウムフェライトが部分的に生成し形状が悪くなっただけでなく、磁化が低くなりすぎる結果となった。さらに比較例３及び比較例５を除き、本焼成後及び表面酸化処理後の少なくともＦｅ及びＴｉを含有する複合酸化物としてストロンチウムフェライトの前駆体であるＳｒ２Ｆｅ２Ｏ５の一部がＴｉ及び／又はＭｎに置換されたＳｒａＦｅｂＴｉｃＯｄ、ＳｒａＦｅｂＭｎｃＴｉｄＯｅ型の複合酸化物であることがわかった。 As is clear from the results in Tables 1 to 8, it was confirmed that in Examples 1 to 15 sufficient characteristic values were obtained when used as electrophotographic carriers. On the other hand, Comparative Examples 1, 3 and 5 had too low resistance, and Comparative Examples 2, 4, 6 and 7 had too high resistance and could not be used as core materials for electrophotographic carriers. In Comparative Example 8, strontium ferrite was partially generated and the shape was deteriorated. In Comparative Example 9, there was no effect of the surface oxidation treatment, and the resistance was too low. Comparative Example 10 was overfired and the shape was poor. In Comparative Example 11, pores were generated on the surface, and an electrophotographic carrier core material not suitable for resin coating was obtained. In Comparative Example 12, not only was strontium ferrite partially formed and the shape deteriorated, but also the magnetization became too low. Further, except for Comparative Example 3 and Comparative Example 5, a part of Sr 2 Fe 2 O 5 which is a precursor of strontium ferrite as a composite oxide containing at least Fe and Ti after the main firing and after the surface oxidation treatment is Ti and It was found that Sr a Fe b Ti c O d substituted for Mn and / or a Sr a Fe b Mn c Ti d O e type composite oxide.

実施例１と同様の方法で平均粒径５９．１７μｍのキャリア芯材粒子を作成し、信越シリコーン社製アクリル変性シリコーン樹脂ＫＲ−９７０６を被覆樹脂として流動床コーティング装置により塗布した。このとき樹脂溶液はキャリア芯材に対する樹脂の固形分で１重量％となるように樹脂を秤量し、樹脂の固形分が１０重量％となるようにトルエンとＭＥＫを重量比で３：１に混合した溶剤を添加したものを使用した。樹脂を塗布した後、完全に揮発分をなくすために２００℃設定の熱交換型攪拌加熱装置で３時間撹拌しながら乾燥させて樹脂被覆キャリアを得た。   Carrier core material particles having an average particle size of 59.17 μm were prepared in the same manner as in Example 1, and applied with a fluidized bed coating apparatus using acrylic modified silicone resin KR-9706 manufactured by Shin-Etsu Silicone Co., Ltd. as a coating resin. At this time, the resin solution is weighed so that the resin solid content with respect to the carrier core is 1% by weight, and toluene and MEK are mixed at a weight ratio of 3: 1 so that the resin solid content is 10% by weight. What added the solvent was used. After applying the resin, in order to completely eliminate the volatile matter, the resin-coated carrier was obtained by drying with stirring in a heat exchange type stirring and heating apparatus set at 200 ° C. for 3 hours.

実施例１と同様の方法で平均粒径５９．１７μｍのキャリア芯材粒子を作成し、信越シリコーン社製シリコーン樹脂ＫＲ−３５０、東レダウコーニング社製アルミニウム系触媒ＣＡＴ−ＡＣ、信越シリコーン社製アミノシランカップリング剤ＫＢＭ−６０３及びライオン社製ケッチェンブラックＥＣ６００ＪＤを被覆樹脂として流動床コーティング装置により塗布した。このとき樹脂溶液はキャリア芯材に対する樹脂の固形分で１．５重量％となるように樹脂を秤量し、樹脂の固形分に対してアルミニウム系触媒ＣＡＴ−ＡＣを２重量％、アミノシランカップリング剤ＫＢＭ−６０３を１０重量％、ケッチェンブラックＥＣ６００ＪＤを１５重量％それぞれ添加した。さらに樹脂の固形分が１０重量％となるようにトルエンを添加し、ＩＫＡ社製ホモジナイザーＴ６５Ｄ ＵＬＴＲＡ−ＴＵＲＲＡＸで３分間前分散を行った後、縦型ビーズミル５分間分散処理を行ったものを樹脂溶液として使用した。樹脂を塗布した後、完全に揮発分をなくすために２５０℃設定の熱風乾燥機で３時間乾燥させて樹脂被覆キャリアを得た。   Carrier core particles having an average particle size of 59.17 μm were prepared in the same manner as in Example 1, and the silicone resin KR-350 manufactured by Shin-Etsu Silicone, the aluminum-based catalyst CAT-AC manufactured by Toray Dow Corning, and the aminosilane manufactured by Shin-Etsu Silicone Coupling agent KBM-603 and Lion Ketjen Black EC600JD were applied as a coating resin by a fluidized bed coating apparatus. At this time, the resin solution is weighed so that the resin solid content with respect to the carrier core is 1.5% by weight, the aluminum catalyst CAT-AC is 2% by weight with respect to the resin solid content, and the aminosilane coupling agent. 10% by weight of KBM-603 and 15% by weight of Ketjen Black EC600JD were added. Further, toluene is added so that the solid content of the resin becomes 10% by weight, and after pre-dispersing for 3 minutes with a homogenizer T65D ULTRA-TURRAX made by IKA, a resin solution obtained by dispersing for 5 minutes in a vertical bead mill is used. Used as. After applying the resin, in order to completely eliminate the volatile matter, the resin-coated carrier was obtained by drying with a hot air dryer set at 250 ° C. for 3 hours.

実施例１と同様の方法で平均粒径５９．１７μｍのキャリア芯材粒子を作成し、三菱レイヨン社製アクリル樹脂ダイヤナールＢＲ−８０を被覆樹脂として万能混合撹拌機により塗布した。このとき樹脂溶液はキャリア芯材に対する樹脂の固形分で０．５重量％となるように樹脂を秤量し、樹脂の固形分が１０重量％となるようにトルエンを添加したものを使用した。なお、樹脂は粉末であるため樹脂溶液は５０℃となるように湯煎し樹脂粉末が完全に溶解させた。樹脂を塗布した後、完全に揮発分をなくすために１４５℃設定の熱風乾燥機で２時間乾燥させて樹脂被覆キャリアを得た。   Carrier core material particles having an average particle diameter of 59.17 μm were prepared in the same manner as in Example 1, and applied with an acrylic resin Dianal BR-80 manufactured by Mitsubishi Rayon Co., Ltd. as a coating resin using a universal mixing stirrer. At this time, a resin solution was used in which the resin was weighed so that the solid content of the resin with respect to the carrier core was 0.5 wt%, and toluene was added so that the solid content of the resin would be 10 wt%. Since the resin is a powder, the resin solution was bathed in water so that the temperature was 50 ° C., and the resin powder was completely dissolved. After applying the resin, in order to completely eliminate the volatile matter, the resin-coated carrier was obtained by drying with a hot air dryer set at 145 ° C. for 2 hours.

実施例１６〜１８について、樹脂被覆後の帯電量測定結果を表９に示す。帯電量の測定方法は上述の通りである。   For Examples 16 to 18, Table 9 shows the charge amount measurement results after resin coating. The method for measuring the charge amount is as described above.

Figure 0005348588
Figure 0005348588

実施例１６〜１８の結果から、本発明に係るキャリア芯材に各種樹脂被覆を行うことで、キャリア芯材の平均粒径が大きくトナー濃度が相対的に高い状態になっているにもかかわらず十分な帯電特性を持った電子写真用キャリアが得られた。   From the results of Examples 16 to 18, although the carrier core material according to the present invention is coated with various resins, the average particle size of the carrier core material is large and the toner concentration is relatively high. An electrophotographic carrier having sufficient charging characteristics was obtained.

本発明に係る電子写真現像剤用キャリア芯材は、各重金属のみならず、Ｍｎを必要以上に用いることなしに、高磁化でありながら中抵抗又は高抵抗といった所望の抵抗が得られ、かつ高い帯電量と優れた帯電安定性を有し、しかも適度な凹凸を有する表面性と揃った形状とを兼ね備える。そして、上記キャリア芯材に樹脂を被覆して得られるキャリアとトナーとからなる電子写真現像剤は、長寿命化が達成され、かつ高い帯電量を有し、帯電安定性にも優れる。また、本発明の製造方法によって、上記キャリア芯材及びキャリアが工業的規模をもって安定的に製造できる。   The carrier core material for an electrophotographic developer according to the present invention can obtain a desired resistance such as medium resistance or high resistance while being highly magnetized without using not only heavy metals but also Mn more than necessary. It has a charge amount and excellent charging stability, and also has a surface shape with appropriate irregularities and a uniform shape. An electrophotographic developer comprising a carrier and a toner obtained by coating the carrier core material with a resin has a long life, has a high charge amount, and is excellent in charging stability. Moreover, the carrier core material and the carrier can be stably produced on an industrial scale by the production method of the present invention.

従って、本発明は、特に高画質の要求されるフルカラー機並びに画像維持の信頼性及び耐久性の要求される高速機の分野に広く使用可能である。   Therefore, the present invention can be widely used in the field of full-color machines that particularly require high image quality and high-speed machines that require image maintenance reliability and durability.

Claims (17)

Ｍｇを０．８〜５重量％、Ｔｉを０．１〜２．５重量％、Ｆｅを６０〜７０重量％及びＳｒを０．２〜２．５重量％含有し、表面酸化処理により表面被覆が形成されている電子写真現像剤用キャリア芯材であって、表面酸化処理前の芯材表面の粗さＲａ処理前に対する表面酸化処理後の芯材表面の粗さＲａ処理後の比（ａ）が、２．３≧Ｒａ処理後／Ｒａ処理前＞１であり、ＳｒのｐＨ４標準液による溶出が５０〜１０００ｐｐｍ、形状係数ＳＦ−２（真円度）が１００〜１２０であることを特徴とする電子写真現像剤用キャリア芯材。 Contains 0.8 to 5% by weight of Mg, 0.1 to 2.5% by weight of Ti, 60 to 70% by weight of Fe and 0.2 to 2.5% by weight of Sr. there a carrier core material for an electrophotographic developer formed, the ratio after the roughness R a process of core material surface after the surface oxidation treatment to that before the roughness R a process of surface oxidation treatment before the core material surface (A) 2.3 ≧ R a after treatment / before Ra treatment > 1, elution of Sr with pH 4 standard solution is 50 to 1000 ppm, and shape factor SF-2 (roundness) is 100 to 120 A carrier core material for an electrophotographic developer, wherein 上記表面酸化処理後のキャリア用芯材にＦｅ２Ｏ３成分が生成している請求項１に記載の電子写真現像剤用キャリア芯材。 The carrier core material for an electrophotographic developer according to claim 1, wherein an Fe 2 O 3 component is generated in the carrier core material after the surface oxidation treatment. Ｍｇを含有するスピネル構造以外に少なくともＦｅ及びＴｉを含有する酸化物の結晶構造を含有する請求項１又は２に記載の電子写真現像剤用キャリア芯材。   3. The carrier core material for an electrophotographic developer according to claim 1, comprising a crystal structure of an oxide containing at least Fe and Ti in addition to the spinel structure containing Mg. ２ｍｍＧａｐ印加電圧５００Ｖにおける抵抗が、５×１０７〜１×１０９Ωである請求項１〜３のいずれかに記載の電子写真現像剤用キャリア芯材。 4. The carrier core material for an electrophotographic developer according to claim 1, wherein the resistance at a 2 mm Gap applied voltage of 500 V is 5 × 10 7 to 1 × 10 9 Ω. Ｍｎを含有し、その含有量が１０重量％以下である請求項１〜４のいずれかに記載の電子写真現像剤用キャリア芯材。   The carrier core material for an electrophotographic developer according to claim 1, which contains Mn and has a content of 10% by weight or less. 見掛け密度が２．３〜２．６ｇ／ｃｍ３である請求項１〜５のいずれかに記載の電子写真現像剤用キャリア芯材。 The carrier core material for an electrophotographic developer according to claim 1, which has an apparent density of 2.3 to 2.6 g / cm 3 . ＢＥＴ比表面積が０．０７５〜０．１５ｍ２／ｇである請求項１〜６のいずれかに記載の電子写真現像剤用キャリア芯材。 The carrier core material for an electrophotographic developer according to claim 1, wherein the BET specific surface area is 0.075 to 0.15 m 2 / g. ３Ｋ・１０００／４π・Ａ／ｍの磁場をかけたときの磁化が５０〜８５Ａｍ２／ｋｇである請求項１〜７のいずれかに記載の電子写真現像剤用キャリア芯材。 The carrier core material for an electrophotographic developer according to any one of claims 1 to 7, which has a magnetization of 50 to 85 Am 2 / kg when a magnetic field of 3K · 1000 / 4π · A / m is applied. レーザー回折式粒度分布測定装置により測定される平均粒径が１５〜１２０μｍである請求項１〜８のいずれかに記載の電子写真現像剤用キャリア芯材。   The carrier core material for an electrophotographic developer according to any one of claims 1 to 8, wherein an average particle size measured by a laser diffraction particle size distribution analyzer is 15 to 120 µm. 請求項１〜９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電子写真現像剤用キャリア。   A carrier for an electrophotographic developer, wherein the surface of the carrier core material according to claim 1 is coated with a resin. 上記樹脂がアクリル樹脂、シリコーン樹脂又は変性シリコーン樹脂である請求項１０記載の電子写真現像剤用キャリア。   The carrier for an electrophotographic developer according to claim 10, wherein the resin is an acrylic resin, a silicone resin, or a modified silicone resin. Ｆｅ、Ｔｉ、Ｍｇ及びＳｒの各化合物を粉砕、混合、仮焼した後、再度粉砕、混合、造粒し、得られた造粒物を１次焼成、本焼成し、さらに解砕、分級、表面酸化処理する電子写真現像剤用キャリア芯材の製造方法であって、上記本焼成が、酸素濃度が５体積％以下で行われることを特徴とする電子写真現像剤用キャリア芯材の製造方法。   After each compound of Fe, Ti, Mg and Sr is pulverized, mixed, calcined, pulverized, mixed and granulated again, the resulting granulated product is subjected to primary firing, main firing, further pulverization, classification, A method for producing a carrier core material for electrophotographic developer for surface oxidation treatment, wherein the main baking is performed at an oxygen concentration of 5% by volume or less. . 上記再度粉砕、混合時にＦｅ化合物、Ｍｇ化合物、Ｔｉ化合物、Ｓｒ化合物、Ｍｎ化合物から選ばれる少なくとも１種の化合物を添加する請求項１２記載の電子写真現像剤用キャリア芯材の製造方法。   The method for producing a carrier core material for an electrophotographic developer according to claim 12, wherein at least one compound selected from an Fe compound, Mg compound, Ti compound, Sr compound, and Mn compound is added during the pulverization and mixing again. 請求項１２又は１３に記載の製造方法で得られたキャリア芯材の表面を樹脂で被覆することを特徴とする電子写真現像剤用キャリアの製造方法。   A method for producing a carrier for an electrophotographic developer, wherein the surface of the carrier core material obtained by the production method according to claim 12 or 13 is coated with a resin. 請求項１０又は１１に記載のキャリアとトナーからなる電子写真現像剤。   An electrophotographic developer comprising the carrier according to claim 10 and a toner. 請求項１４記載の製造方法により得られたキャリアとトナーからなる電子写真現像剤。   An electrophotographic developer comprising a carrier and a toner obtained by the production method according to claim 14. 補給用現像剤として用いられる請求項１５又は１６記載の電子写真現像剤。   The electrophotographic developer according to claim 15 or 16, which is used as a replenishment developer.
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