JP2017146495A - Carrier core material - Google Patents
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Abstract
Description
本発明は、キャリア芯材に関し、より詳細にはフェライト粒子から構成されるキャリア芯材などに関するものである。 The present invention relates to a carrier core material, and more particularly to a carrier core material composed of ferrite particles.
例えば、電子写真方式を用いたファクシミリやプリンター、複写機などの画像形成装置では、感光体の表面に形成された静電潜像にトナーを付着させて可視像化し、この可視像を用紙等に転写した後、加熱・加圧して溶融定着させている。高画質化やカラー化の観点から、現像剤としては、キャリアとトナーとを含むいわゆる二成分現像剤が広く使用されている。 For example, in an image forming apparatus such as a facsimile, printer, or copier using an electrophotographic method, a toner is attached to an electrostatic latent image formed on the surface of a photosensitive member to make a visible image, and the visible image is formed on paper. After being transferred to, for example, it is melted and fixed by heating and pressing. A so-called two-component developer including a carrier and a toner is widely used as a developer from the viewpoint of high image quality and colorization.
二成分現像剤を用いた現像方式では、キャリアとトナーとを現像装置内で撹拌混合し、摩擦によってトナーを所定量まで帯電させる。そして、回転する現像ローラに現像剤を供給し、現像ローラ上で磁気ブラシを形成させて、磁気ブラシを介して感光体へトナーを電気的に移動させて感光体上の静電潜像を可視像化する。トナー移動後のキャリアは現像ローラから剥離され、現像装置内で再びトナーと混合される。このため、キャリアの特性として、磁気ブラシを形成する磁気特性と、所望の電荷をトナーに付与する帯電特性などが要求される。 In the developing method using a two-component developer, the carrier and the toner are stirred and mixed in the developing device, and the toner is charged to a predetermined amount by friction. Then, a developer is supplied to the rotating developing roller, a magnetic brush is formed on the developing roller, and the toner is electrically moved to the photosensitive member via the magnetic brush, so that an electrostatic latent image on the photosensitive member can be formed. Visualize. The carrier after the toner movement is peeled off from the developing roller and mixed with the toner again in the developing device. For this reason, as a characteristic of the carrier, a magnetic characteristic for forming a magnetic brush and a charging characteristic for imparting a desired charge to the toner are required.
このようなキャリアとして、マグネタイトや各種フェライト等の磁性粒子の表面を樹脂で被覆したものが一般に用いられている。キャリア芯材としての磁性粒子には、良好な磁気的特性と共に、トナーに対する良好な摩擦帯電特性が要求される。このような特性を満たすキャリア芯材として種々の形状のものが提案されている。 As such a carrier, one in which the surface of magnetic particles such as magnetite and various ferrites is coated with a resin is generally used. The magnetic particles as the carrier core material are required to have good magnetic characteristics as well as good triboelectric charging characteristics for the toner. Various shapes of carrier core materials that satisfy such characteristics have been proposed.
例えば特許文献１では、Ｓｒを含有し、特定の形状と磁気特性とを有する電子写真現像用フェライトキャリア芯材が提案されている。また、特許文献２では、特定の組成を有し、格子定数が特定範囲で表面酸化被膜が形成された電子写真現像用フェライトキャリア芯材が提案されている。 For example, Patent Document 1 proposes a ferrite carrier core material for electrophotographic development that contains Sr and has a specific shape and magnetic properties. Further, Patent Document 2 proposes a ferrite carrier core material for electrophotographic development having a specific composition and having a surface oxide film formed with a lattice constant in a specific range.
しかしながら、Ｓｒの添加によってキャリア芯材の凹凸化を図ると、ＳｒＦｅ１２Ｏ１９が生成してキャリア芯材の残留磁化が高くなる。 However, when the carrier core material is made uneven by the addition of Sr, SrFe 12 O 19 is generated and the residual magnetization of the carrier core material becomes high.
現像後のキャリア、すなわち、感光体表面の静電潜像にトナーが移動した後のキャリアは、現像ローラから剥離し現像装置内で再びトナーと混合する必要があるところ、キャリア芯材の残留磁化が高くなると、現像ローラからのキャリアの剥離が難しくなり、トナー付着量の少ないキャリアが再び現像領域に搬送されることになる。これにより、画像濃度ムラが発生することがある。 The carrier after development, that is, the carrier after the toner has moved to the electrostatic latent image on the surface of the photoreceptor, needs to be peeled off from the developing roller and mixed with the toner again in the developing device. When the value becomes high, it becomes difficult to peel off the carrier from the developing roller, and the carrier with a small toner adhesion amount is conveyed again to the developing region. As a result, image density unevenness may occur.
そこで、本発明の目的は、フェライト粒子から構成されるキャリア芯材において、Ｓｒの添加による残留磁化の上昇を抑えながら粒子の凹凸化を図ることにある。 Therefore, an object of the present invention is to make the particles uneven while suppressing an increase in residual magnetization due to the addition of Sr in a carrier core material composed of ferrite particles.
また、本発明の他の目的は、長期間の使用においても安定して良好な画質画像を形成することができる電子写真現像剤用キャリア及び電子写真現像剤を提供することである。 Another object of the present invention is to provide an electrophotographic developer carrier and an electrophotographic developer that can stably form a good image quality even when used for a long period of time.
前記目的を達成する本発明に係るキャリア芯材は、Ｆｅ：４５〜６５ｗｔ％、Ｍｎ：１５〜３０ｗｔ％、Ｓｒ：０．１〜５．０ｗｔ％、Ｔｉ：０．１〜２．５ｗｔ％を含有するフェライト粒子から構成されるキャリア芯材であって、Ｔｉ／Ｓｒがｍｏｌ比で２．０以下であり、Ｓｒフェライトの板状結晶が表面に析出しているフェライト粒子の個数割合が１０個数％以下であることを特徴とする。なお、本明細書において「〜」は特に断りのない限り、その前後に記載の数値を下限値及び上限値として含む意味で使用する。 The carrier core material according to the present invention that achieves the above object includes Fe: 45 to 65 wt%, Mn: 15 to 30 wt%, Sr: 0.1 to 5.0 wt%, Ti: 0.1 to 2.5 wt%. A carrier core material comprising ferrite particles contained therein, wherein Ti / Sr is 2.0 or less in terms of mol ratio, and the number ratio of ferrite particles on which Sr ferrite plate-like crystals are precipitated is 10 % Or less. In the present specification, unless otherwise specified, “to” is used in the sense of including the numerical values described before and after it as lower and upper limits.
ここで、キャリア芯材の算術平均粗さＲａは０．３μｍ以上であり、１個粒子の算術平均粗さＲａが０．１μｍ以下のフェライト粒子の個数割合は１０個数％以下であるのが好ましい。 Here, the arithmetic average roughness Ra of the carrier core material is 0.3 μm or more, and the number ratio of ferrite particles having an arithmetic average roughness Ra of one particle of 0.1 μm or less is preferably 10 number% or less. .
キャリア芯材の残留磁化σｒは０．９（Ａ・ｍ２／ｋｇ）以下であるのが好ましい。 The residual magnetization σr of the carrier core material is preferably 0.9 (A · m 2 / kg) or less.
磁場１０００（１０３／４π・Ａ／ｍ）における磁化σ１ｋは５０〜７０Ａｍ２／ｋｇの範囲であるのが好ましい。 The magnetization σ 1k at a magnetic field of 1000 (10 3 / 4π · A / m) is preferably in the range of 50 to 70 Am 2 / kg.
また下記式（１）から算出されるキャリア芯材の包絡係数Ｅは６．０以上であるのが好ましい。
Ｅ＝［（Ｌ１−Ｌ２）／Ｌ２］×１００ ・・・・・・（１）
（式中、Ｌ１はキャリア芯材投影像の外周長を表し、Ｌ２はキャリア芯材投影像の包絡線の長さを表す。）
Moreover, it is preferable that the envelope coefficient E of the carrier core material calculated from the following formula (1) is 6.0 or more.
E = [(L1-L2) / L2] × 100 (1)
(In the formula, L1 represents the outer peripheral length of the carrier core material projection image, and L2 represents the length of the envelope of the carrier core material projection image.)
キャリア芯材の帯電量は５０〜７０μＣ／ｇの範囲であるのが好ましい。 The charge amount of the carrier core material is preferably in the range of 50 to 70 μC / g.
また本発明によれば、前記のいずれかに記載のキャリア芯材の表面が樹脂で被覆されていることを特徴とする電子写真現像用キャリアが提供される。 According to the present invention, there is also provided an electrophotographic developing carrier characterized in that the surface of the carrier core material described above is coated with a resin.
さらに本発明によれば、前記の電子写真現像用キャリアとトナーとを含む電子写真用現像剤が提供される。 Furthermore, according to the present invention, there is provided an electrophotographic developer comprising the above-mentioned electrophotographic developing carrier and a toner.
本発明のキャリア芯材では、Ｓｒの添加による残留磁化の上昇を抑えることができるので、現像後のキャリアを現像ローラから剥離することが容易となる。この結果、現像領域へは現像ローラに新たに供給された、所定のトナーが付着したキャリアが搬送され画像濃度ムラが抑制される。 In the carrier core material of the present invention, an increase in residual magnetization due to the addition of Sr can be suppressed, so that it becomes easy to peel the developed carrier from the developing roller. As a result, the carrier newly supplied to the developing roller, to which the predetermined toner adheres, is conveyed to the developing area, and image density unevenness is suppressed.
また、キャリア芯材の凹凸化が図られるので、樹脂被覆してキャリアとされた際にキャリア芯材の一部が外部に露出し、現像ローラ上にキャリアが連なって磁気ブラシを形成したときに、キャリア芯材の露出部分が繋がるようにしてキャリアの有する電荷（カウンターチャージ）が現像ローラに流れるようになる。これにより、カウンターチャージがキャリアに蓄積されることに起因する、感光体上に移動したトナーがキャリアに引き戻される不具合が抑制される。 In addition, since the carrier core material is made uneven, when the carrier is coated with a resin, a part of the carrier core material is exposed to the outside, and the carrier is connected to the developing roller to form a magnetic brush. Then, the charge (counter charge) of the carrier flows to the developing roller so that the exposed portions of the carrier core material are connected. As a result, a problem that the toner that has moved onto the photosensitive member due to the accumulation of the counter charge on the carrier is pulled back to the carrier is suppressed.
また、本発明の電子写真現像剤用キャリア及び電子写真現像剤によれば、長期間の使用においても安定して良好な画質画像を形成することができる。 In addition, according to the carrier for an electrophotographic developer and the electrophotographic developer of the present invention, a good image quality can be stably formed even after long-term use.
本発明者等は、Ｓｒの添加によってキャリア芯材の凹凸化を図りながら、残留磁化の上昇を抑えられないか鋭意検討を重ねた結果、Ｓｒと共にＴｉを所定の割合で添加すればよいことを見出した。すなわち、本発明の大きな特徴の一つは、Ｓｒの含有量が０．１〜５．０ｗｔ％、Ｔｉの含有量が０．１〜２．５ｗｔ％であって、Ｔｉ／Ｓｒのｍｏｌ比が２．０以下であることにある。 As a result of intensive studies on whether or not the increase in the residual magnetization can be suppressed while making the carrier core material uneven by adding Sr, the present inventors have added Ti together with Sr in a predetermined ratio. I found it. That is, one of the major features of the present invention is that the Sr content is 0.1 to 5.0 wt%, the Ti content is 0.1 to 2.5 wt%, and the Ti / Sr molar ratio is It is that it is 2.0 or less.
Ｓｒを含有させることにより、焼成工程における昇温段階でまずＳｒフェライト（ＳｒＦｅ１２Ｏ１９）の板状結晶が生成する。このＳｒフェライトの板状結晶の生成によって、次に生成するＭｎフェライトの粒子の周方向への結晶成長が阻害されて半径方向すなわち粒子外方への成長が促される。これによって粒子の凹凸化が進む。そして、焼成温度に達するとＳｒフェライトが分解する一方、Ｍｎフェライトの生成が本格化する。その後、冷却段階において、Ｔｉが存在しない場合にはＳｒフェライトの板状結晶が再び生成されるが、Ｔｉが存在する場合にはＳｒフェライトよりもチタン酸ストロンチウム（ＳｒＴｉＯ３）が優先して生成される。これによってＳｒフェライトの再生成が抑制される。この結果、得られるフェライト粒子は、表面が凹凸で且つＳｒフェライトに起因する残留磁化の上昇が抑制されたものとなる。 By containing Sr, first, plate-like crystals of Sr ferrite (SrFe 12 O 19 ) are generated at the temperature rising stage in the firing step. The generation of the Sr ferrite plate-like crystal inhibits the crystal growth of the next produced Mn ferrite particles in the circumferential direction and promotes the growth in the radial direction, that is, outward of the particles. Thereby, the unevenness of the particles proceeds. When the firing temperature is reached, the Sr ferrite is decomposed, while the production of Mn ferrite becomes serious. Thereafter, in the cooling stage, when Ti is not present, a plate-like crystal of Sr ferrite is generated again. However, when Ti is present, strontium titanate (SrTiO 3 ) is generated in preference to Sr ferrite. The This suppresses the regeneration of Sr ferrite. As a result, the obtained ferrite particles have an uneven surface and suppressed increase in residual magnetization due to Sr ferrite.
Ｓｒの含有量が０．１ｗｔ％未満であると粒子の十分な凹凸化が図れない。一方、Ｓｒの含有量が５．０ｗｔ％を超えるとフェライト粒子の残留磁化が大きくなりすぎ、現像ローラからのキャリアの剥離が困難になる。 If the Sr content is less than 0.1 wt%, the particles cannot be sufficiently uneven. On the other hand, if the Sr content exceeds 5.0 wt%, the residual magnetization of the ferrite particles becomes too large, and it becomes difficult to peel off the carrier from the developing roller.
また、Ｔｉの含有量が０．１ｗｔ％未満であるとＳｒフェライトの生成を十分には抑制できない。一方、Ｔｉの含有量が２．５ｗｔ％を超えると、磁力が下がり過ぎキャリア飛散が多くなる。 On the other hand, when the Ti content is less than 0.1 wt%, the formation of Sr ferrite cannot be sufficiently suppressed. On the other hand, if the Ti content exceeds 2.5 wt%, the magnetic force is too low and carrier scattering increases.
そしてまた、Ｔｉ／Ｓｒのｍｏｌ比が２．０以下であることも重要である。前記のｍｏｌ比が２．０を超えると、昇温段階におけるＳｒフェライトの生成が抑えられ粒子の凹凸化が図れない。 It is also important that the Ti / Sr molar ratio is 2.0 or less. When the molar ratio exceeds 2.0, the formation of Sr ferrite in the temperature rising stage is suppressed and the unevenness of the particles cannot be achieved.
本発明のキャリア芯材では、Ｓｒフェライトの板状結晶が表面に析出しているフェライト粒子の個数割合は１０個数％以下である必要がある。Ｓｒフェライトの板状結晶が表面に析出しているフェライト粒子の個数割合が１０個数％を超えると、残留磁化や保磁力が増加し画像濃度ムラが生じやすくなる。 In the carrier core material of the present invention, the number ratio of ferrite particles on which Sr ferrite plate-like crystals are precipitated needs to be 10% by number or less. When the ratio of the number of ferrite particles having Sr ferrite plate-like crystals precipitated on the surface exceeds 10% by number, residual magnetization and coercive force increase and image density unevenness tends to occur.
フェライト粒子表面の凹凸化とＳｒフェライトの再析出の抑制は、前述のようにＴｉを添加する他、焼成工程における酸素濃度調整によっても制御できる。詳細は、後述するキャリア芯材の製造において説明する。 The unevenness of the ferrite particle surface and the suppression of reprecipitation of Sr ferrite can be controlled by adjusting the oxygen concentration in the firing step in addition to adding Ti as described above. Details will be described in the manufacture of the carrier core material described later.
なお、Ｓｒフェライトの板状結晶とは、図１に示されるような粒子表面に観察される最大長と最短長を有した板状の結晶のこという。板状結晶の最大長は粒子半径以上である。また、板状結晶のアスペクト比 最大長／最短長は３以上である。 In addition, the plate-like crystal of Sr ferrite means a plate-like crystal having the maximum length and the shortest length observed on the particle surface as shown in FIG. The maximum length of the plate crystal is not less than the particle radius. Further, the aspect ratio maximum length / minimum length of the plate crystal is 3 or more.
本発明のキャリア芯材の算術平均粗さＲａは０．３μｍ以上であるのが好ましい。加えて、１個粒子の算術平均粗さＲａが０．１μｍ以下のフェライト粒子、すなわち表面の凹凸が少ないフェライト粒子の個数割合が１０個数％以下であるのが好ましい。キャリア芯材の算術平均粗さＲａを０．３μｍ以上とし、表面の凹凸が少ないフェライト粒子を１０個数％以下に抑えることによって、キャリアにカウンターチャージが蓄積されるのが抑えられ、トナーに対する良好な摩擦帯電性が得られる。 The arithmetic average roughness Ra of the carrier core material of the present invention is preferably 0.3 μm or more. In addition, it is preferable that the number ratio of ferrite particles having an arithmetic average roughness Ra of one particle of 0.1 μm or less, that is, ferrite particles having few surface irregularities is 10 number% or less. By setting the arithmetic average roughness Ra of the carrier core material to 0.3 μm or more and suppressing ferrite particles with few surface irregularities to 10% by number or less, it is possible to suppress the accumulation of counter charge on the carrier, and to improve the toner. Triboelectric chargeability is obtained.
本発明のキャリア芯材の残留磁化は、０．９（Ａ・ｍ２／ｋｇ）以下であるのが好ましい。キャリア芯材の残留磁化が０．９（Ａ・ｍ２／ｋｇ）を超えると、キャリアの流動性、帯電付与能力が悪化し、トナー飛散が生じやすくなる。より好ましい残留磁化は、０．７（Ａ・ｍ２／ｋｇ）〜０．９（Ａ・ｍ２／ｋｇ）である。 The residual magnetization of the carrier core material of the present invention is preferably 0.9 (A · m 2 / kg) or less. When the residual magnetization of the carrier core material exceeds 0.9 (A · m 2 / kg), the fluidity of the carrier and the charge imparting ability are deteriorated, and toner scattering tends to occur. More preferred residual magnetization is 0.7 (A · m 2 /kg)~0.9(A · m 2 / kg).
本発明のキャリア芯材の磁場１０００（１０３／４π・Ａ／ｍ）における磁化σ１ｋは５０〜７０Ａｍ２／ｋｇの範囲であるのが好ましい。キャリア芯材の磁化σ１ｋをこの範囲とすることによって、現像ローラ表面の磁気ブラシの形成と現像ローラからのキャリアの剥離の容易性とのバランスが図られる。 The magnetization σ 1k of the carrier core material of the present invention at a magnetic field of 1000 (10 3 / 4π · A / m) is preferably in the range of 50 to 70 Am 2 / kg. By setting the magnetization σ 1k of the carrier core material within this range, the balance between the formation of the magnetic brush on the surface of the developing roller and the ease of peeling of the carrier from the developing roller can be achieved.
本発明のキャリア芯材の保持力は、１１（Ｏｅ：Ａ／ｍ×１０３／（４π））未満であるのが好ましい。キャリア芯材の保持力が１１（Ａ／ｍ×１０３／（４π））以上あると、キャリアの流動性、帯電付与能力が悪化しやすくなる。より好ましい保持力は、８（Ａ／ｍ×１０３／（４π））以上１１（Ａ／ｍ×１０３／（４π））未満である。 The holding power of the carrier core material of the present invention is preferably less than 11 (Oe: A / m × 10 3 / (4π)). When the holding power of the carrier core material is 11 (A / m × 10 3 / (4π)) or more, the fluidity and charge imparting ability of the carrier are likely to deteriorate. A more preferable holding force is 8 (A / m × 10 3 / (4π)) or more and less than 11 (A / m × 10 3 / (4π)).
また、本発明のキャリア芯材の包絡係数Ｅは６．０以上であるのが好ましい。粒子表面の凹凸が少ないほど包絡係数はゼロに近づく。本発明では、キャリア芯材の包絡係数Ｅを前記範囲とする、すなわちキャリア芯材表面に所定の凹凸を形成することによって、樹脂被覆キャリアとしたときに、キャリア芯材の凸部の一部が露出するようにした。これにより、トナーとの摩擦帯電によってカウンターチャージがキャリアに蓄積されていくのが抑制される。 The envelope coefficient E of the carrier core material of the present invention is preferably 6.0 or more. The smaller the irregularities on the particle surface, the closer the envelope coefficient approaches zero. In the present invention, when the envelope coefficient E of the carrier core material is within the above range, that is, when the resin core is formed by forming predetermined irregularities on the surface of the carrier core material, a part of the convex portions of the carrier core material is formed. I was exposed. This suppresses the accumulation of the counter charge in the carrier due to the frictional charging with the toner.
本発明のキャリア芯材の帯電量は５０〜７０μＣ／ｇの範囲が好ましい。帯電量をこの範囲とすることによってトナーに対する良好な帯電付与性が得られ、優れた画質を得ることができる。 The charge amount of the carrier core material of the present invention is preferably in the range of 50 to 70 μC / g. By setting the charge amount within this range, good charge imparting property to the toner can be obtained, and excellent image quality can be obtained.
本発明のキャリア芯材を構成するフェライト粒子の主組成はＭｎフェライトであり、Ｆｅを４５〜６５ｗｔ％、Ｍｎを１５〜３０ｗｔ％含有する。 The main composition of the ferrite particles constituting the carrier core material of the present invention is Mn ferrite, containing 45 to 65 wt% Fe and 15 to 30 wt% Mn.
本発明のキャリア芯材の粒径に特に限定はないが、体積平均粒子径で数十μｍ程度が好ましく、粒度分布はシャープであるのが好ましい。 The particle diameter of the carrier core material of the present invention is not particularly limited, but is preferably about several tens of μm in volume average particle diameter, and the particle size distribution is preferably sharp.
本発明のキャリア芯材の製造方法に特に限定はないが、以下に説明する製造方法が好適である。 Although there is no limitation in particular in the manufacturing method of the carrier core material of this invention, the manufacturing method demonstrated below is suitable.
まず、Ｆｅ成分原料、Ｍｎ成分原料、Ｓｒ成分原料、Ｔｉ成分原料を秤量し、原料混合粉を作製する。Ｆｅ成分原料としては、Ｆｅ２Ｏ３等が好適に使用される。Ｍｎ成分原料としては、ＭｎＣＯ３、Ｍｎ３Ｏ４等が好適に使用され、Ｓｒ成分原料としては、ＳｒＣＯ３、Ｓｒ（ＮＯ３）２などが好適に使用され、Ｔｉ成分原料としては、ＴｉＯ２などが好適に使用される。 First, an Fe component raw material, an Mn component raw material, an Sr component raw material, and a Ti component raw material are weighed to produce a raw material mixed powder. As the Fe component material, Fe 2 O 3 or the like is preferably used. As the Mn component material, MnCO 3 , Mn 3 O 4 or the like is preferably used, as the Sr component material, SrCO 3 , Sr (NO 3 ) 2 or the like is preferably used, and as the Ti component material, TiO 2 is used. Etc. are preferably used.
次いで、作製した原料混合粉を仮焼成する。仮焼成の温度としては７５０℃〜９００℃の範囲が好ましい。７５０℃以上であれば、仮焼による一部フェライト化が進み、焼成時のガス発生量が少なく、固体間反応が十分に進むため好ましい。一方、９００℃以下であれば、仮焼による焼結が弱く、後のスラリー粉砕工程で原料を十分に粉砕できるので好ましい。また、仮焼成時の雰囲気としては大気雰囲気が好ましい。 Next, the prepared raw material mixed powder is temporarily fired. The pre-baking temperature is preferably in the range of 750 ° C to 900 ° C. If it is 750 degreeC or more, since part ferrite-ization by calcination advances, there is little gas generation amount at the time of baking, and reaction between solids fully progresses, and it is preferable. On the other hand, if it is 900 degrees C or less, since sintering by calcination is weak and a raw material can fully be grind | pulverized at a later slurry grinding | pulverization process, it is preferable. Moreover, an air atmosphere is preferable as the atmosphere at the time of temporary firing.
そして、仮焼成した原料を解粒して分散媒中に投入しスラリーを作製する。なお、仮焼成することなく原料混合粉を分散媒中に投入しスラリーを作製してもよい。本発明で使用する分散媒としては水が好適である。分散媒には、前記仮焼成原料の他、必要によりバインダー、分散剤等を配合してもよい。バインダーとしては、例えば、ポリビニルアルコールが好適に使用できる。バインダーの配合量としてはスラリー中の濃度が０．５質量％〜２質量％程度とするのが好ましい。また、分散剤としては、例えば、ポリカルボン酸アンモニウム等が好適に使用できる。分散剤の配合量としてはスラリー中の濃度が０．５質量％〜２質量％程度とするのが好ましい。その他、潤滑剤や焼結促進剤等を配合してもよい。スラリーの固形分濃度は５０質量％〜９０質量％の範囲が望ましい。より好ましくは６０質量％〜８０質量％である。６０質量％以上であれば、造粒品中に粒子内細孔が少なく、焼成時の焼結不足を防ぐことができる。一方、８０質量％以下であれば、会合粒子が少なく、粒子形状による流動性悪化を防ぐことができる。 Then, the calcined raw material is pulverized and charged into a dispersion medium to prepare a slurry. Note that the raw material mixed powder may be charged into the dispersion medium without pre-baking to produce a slurry. Water is preferred as the dispersion medium used in the present invention. In addition to the calcined raw material, a binder, a dispersant and the like may be blended in the dispersion medium as necessary. For example, polyvinyl alcohol can be suitably used as the binder. As a compounding quantity of a binder, it is preferable that the density | concentration in a slurry shall be about 0.5 mass%-2 mass%. Moreover, as a dispersing agent, polycarboxylate ammonium etc. can be used conveniently, for example. The blending amount of the dispersing agent is preferably about 0.5% by mass to 2% by mass in the slurry. In addition, you may mix | blend a lubricant, a sintering accelerator, etc. The solid content concentration of the slurry is desirably in the range of 50 mass% to 90 mass%. More preferably, it is 60 mass%-80 mass%. If it is 60 mass% or more, there are few intraparticle pores in a granulated product, and it can prevent the sintering shortage at the time of baking. On the other hand, if it is 80 mass% or less, there are few associated particles and the fluidity | liquidity deterioration by particle shape can be prevented.
次に、以上のようにして作製されたスラリーを湿式粉砕する。例えば、ボールミルや振動ミルを用いて所定時間湿式粉砕する。粉砕後の原材料の体積平均粒径は１０μｍ以下が好ましく、より好ましくは５μｍ以下である。振動ミルやボールミルには、所定粒径のメディアを内在させるのがよい。メディアの材質としては、鉄系のクロム鋼や酸化物系のジルコニア、チタニア、アルミナなどが挙げられる。粉砕工程の形態としては連続式及び回分式のいずれであってもよい。粉砕物の粒径は、粉砕時間や回転速度、使用するメディアの材質・粒径などによって調整される。 Next, the slurry produced as described above is wet pulverized. For example, wet grinding is performed for a predetermined time using a ball mill or a vibration mill. The volume average particle size of the raw material after pulverization is preferably 10 μm or less, more preferably 5 μm or less. The vibration mill or ball mill preferably contains a medium having a predetermined particle diameter. Examples of the material of the media include iron-based chromium steel and oxide-based zirconia, titania, and alumina. As a form of a grinding | pulverization process, any of a continuous type and a batch type may be sufficient. The particle size of the pulverized product is adjusted depending on the pulverization time and rotation speed, the material and particle size of the media used, and the like.
そして、粉砕されたスラリーを噴霧乾燥させて造粒する。具体的には、スプレードライヤーなどの噴霧乾燥機にスラリーを導入し、雰囲気中へ噴霧することによって球状に造粒する。噴霧乾燥時の雰囲気温度は１００℃〜３００℃の範囲が好ましい。これにより、粒径１０μｍ〜２００μｍの球状の造粒物が得られる。なお、得られた造粒物は、振動ふるい等を用いて、粗大粒子や微粉を除去し粒度分布をシャープなものとするのが望ましい。 Then, the pulverized slurry is spray-dried and granulated. Specifically, the slurry is introduced into a spray dryer such as a spray dryer, and granulated into a spherical shape by spraying into the atmosphere. The atmospheric temperature during spray drying is preferably in the range of 100 ° C to 300 ° C. Thereby, a spherical granulated product having a particle diameter of 10 μm to 200 μm is obtained. In addition, it is desirable that the obtained granulated product has a sharp particle size distribution by removing coarse particles and fine powder using a vibration sieve or the like.
次に、造粒物を所定温度に加熱した炉に投入して、フェライト粒子を合成するための一般的な手法で焼成することにより、フェライト粒子を生成させる。焼成温度としては１１００℃以上１３００℃以下の範囲が好ましい。焼成温度が１１００℃より低い温度であると、相変態が起こりにくくなるとともに焼結も進みにくくなり、Ｓｒフェライトの板状結晶が得られず粒子の凹凸化が促進しないおそれがある。また、焼成温度が１３００℃を超えると、過剰焼結による過大グレインの発生がするおそれがある。前記焼成温度に至るまでの昇温速度としては２００℃／ｈ〜５００℃／ｈの範囲が好ましい。 Next, the granulated material is put into a furnace heated to a predetermined temperature, and sintered by a general method for synthesizing ferrite particles, thereby generating ferrite particles. The firing temperature is preferably in the range of 1100 ° C to 1300 ° C. When the firing temperature is lower than 1100 ° C., it is difficult for phase transformation to occur and sintering is difficult to proceed, so that Sr ferrite plate-like crystals cannot be obtained and the unevenness of the particles may not be promoted. On the other hand, if the firing temperature exceeds 1300 ° C., excessive grains may be generated due to excessive sintering. The rate of temperature increase up to the firing temperature is preferably in the range of 200 ° C / h to 500 ° C / h.
ここで重要なことは、焼成工程における酸素濃度を昇温及び焼結時は高くして、冷却時は低くすることである。焼成工程における昇温及び焼結時の酸素濃度を高くすることによって、Ｓｒフェライトの板状結晶の析出を促進させて粒子の凹凸化を図る。具体的には、酸素濃度を３００００ｐｐｍ〜８０００ｐｐｍの範囲とする。一方、冷却時は酸素濃度を低くすることによって、焼結段階で一旦分解したＳｒフェライトの再析出を抑制する。具体的には酸素濃度を８０００ｐｐｍ未満の範囲とする。これにより、Ｔｉの添加と相まって、粒子の凹凸化が図れると同時にＳｒフェライトの析出の抑制が図れる。 What is important here is that the oxygen concentration in the firing step is increased during temperature rising and sintering, and is decreased during cooling. By increasing the temperature rise and the oxygen concentration during sintering in the firing step, precipitation of plate crystals of Sr ferrite is promoted to make the particles uneven. Specifically, the oxygen concentration is set in the range of 30000 ppm to 8000 ppm. On the other hand, by reducing the oxygen concentration during cooling, reprecipitation of Sr ferrite once decomposed in the sintering stage is suppressed. Specifically, the oxygen concentration is set to a range of less than 8000 ppm. Thereby, in combination with the addition of Ti, the unevenness of the particles can be achieved, and at the same time, the precipitation of Sr ferrite can be suppressed.
このようにして得られたフェライト粒子を必要により解粒する。具体的には、例えば、ハンマーミル等によって焼成物を解粒する。解粒工程の形態としては連続式及び回分式のいずれであってもよい。そして、必要により、粒径を所定範囲に揃えるため分級を行ってもよい。分級方法としては、風力分級や篩分級など従来公知の方法を用いることができる。また、風力分級機で１次分級した後、振動篩や超音波篩で粒径を所定範囲に揃えるようにしてもよい。さらに、分級工程後に、磁場選鉱機によって非磁性粒子を除去するようにしてもよい。フェライト粒子の体積平均粒子径としては２０μｍ〜６０μｍの範囲が好ましい。 The ferrite particles thus obtained are pulverized as necessary. Specifically, for example, the fired product is pulverized by a hammer mill or the like. The form of the granulation step may be either a continuous type or a batch type. And if necessary, classification may be performed in order to make the particle size in a predetermined range. As a classification method, a conventionally known method such as air classification or sieve classification can be used. In addition, after primary classification with an air classifier, the particle size may be aligned within a predetermined range with a vibration sieve or an ultrasonic sieve. Furthermore, you may make it remove a nonmagnetic particle with a magnetic field separator after a classification process. The volume average particle diameter of the ferrite particles is preferably in the range of 20 μm to 60 μm.
その後、必要に応じて、分級後のフェライト粒子を酸化性雰囲気中で加熱して、粒子表面に酸化被膜を形成してフェライト粒子の高抵抗化を図ってもよい（高抵抗化処理）。酸化性雰囲気としては大気雰囲気又は酸素と窒素の混合雰囲気のいずれでもよい。また、加熱温度は、２００℃〜８００℃の範囲が好ましく、２５０℃〜６００℃の範囲がさらに好ましい。加熱時間は０．５時間〜５時間の範囲が好ましい。 Thereafter, if necessary, the ferrite particles after classification may be heated in an oxidizing atmosphere to form an oxide film on the particle surface to increase the resistance of the ferrite particles (high resistance treatment). The oxidizing atmosphere may be either an air atmosphere or a mixed atmosphere of oxygen and nitrogen. The heating temperature is preferably in the range of 200 ° C to 800 ° C, and more preferably in the range of 250 ° C to 600 ° C. The heating time is preferably in the range of 0.5 hours to 5 hours.
以上のようにして作製したフェライト粒子を本発明のキャリア芯材として用いる。そして、所望の帯電性等を得るために、キャリア芯材の外周を樹脂で被覆して電子写真現像用キャリアとする。 The ferrite particles produced as described above are used as the carrier core material of the present invention. Then, in order to obtain desired chargeability and the like, the outer periphery of the carrier core material is coated with a resin to obtain an electrophotographic developing carrier.
キャリア芯材の表面を被覆する樹脂としては、従来公知のものが使用でき、例えば、ポリエチレン、ポリプロピレン、ポリ塩化ビニル、ポリ−４−メチルペンテン−１、ポリ塩化ビニリデン、ＡＢＳ（アクリロニトリル−ブタジエン−スチレン）樹脂、ポリスチレン、（メタ）アクリル系樹脂、ポリビニルアルコール系樹脂、並びにポリ塩化ビニル系やポリウレタン系、ポリエステル系、ポリアミド系、ポリブタジエン系等の熱可塑性エストラマー、フッ素シリコーン系樹脂などが挙げられる。 As the resin for coating the surface of the carrier core material, conventionally known resins can be used, for example, polyethylene, polypropylene, polyvinyl chloride, poly-4-methylpentene-1, polyvinylidene chloride, ABS (acrylonitrile-butadiene-styrene). ) Resin, polystyrene, (meth) acrylic resin, polyvinyl alcohol resin, polyvinyl chloride, polyurethane, polyester, polyamide, polybutadiene, and other thermoplastic elastomers, and fluorosilicone resins.
キャリア芯材の表面を樹脂で被覆するには、樹脂の溶液又は分散液をキャリア芯材に施せばよい。塗布溶液用の溶媒としては、トルエン、キシレン等の芳香族炭化水素系溶媒；アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン系溶媒；テトラヒドロフラン、ジオキサン等の環状エーテル類溶媒；エタノール、プロパノール、ブタノール等のアルコール系溶媒；エチルセロソルブ、ブチルセロソルブ等のセロソルブ系溶媒；酢酸エチル、酢酸ブチル等のエステル系溶媒；ジメチルホルムアミド、ジメチルアセトアミド等のアミド系溶媒などの１種又は２種以上を用いることができる。塗布溶液中の樹脂成分濃度は、一般に０．００１質量％〜３０質量％、特に０．００１質量％〜２質量％の範囲内にあるのがよい。 In order to coat the surface of the carrier core material with the resin, a resin solution or dispersion may be applied to the carrier core material. Solvents for the coating solution include aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cyclic ether solvents such as tetrahydrofuran and dioxane; ethanol, propanol, and butanol Alcohol solvents such as ethyl cellosolve, cellosolve solvents such as butyl cellosolve; ester solvents such as ethyl acetate and butyl acetate; amide solvents such as dimethylformamide and dimethylacetamide, etc. . The resin component concentration in the coating solution should generally be in the range of 0.001% to 30% by weight, particularly 0.001% to 2% by weight.
キャリア芯材への樹脂の被覆方法としては、例えばスプレードライ法や流動床法あるいは流動床を用いたスプレードライ法、浸漬法等を用いることができる。これらの中でも、少ない樹脂量で効率的に塗布できる点で流動床法が特に好ましい。樹脂被覆量は、例えば流動床法の場合には吹き付ける樹脂溶液量や吹き付け時間によって調整することができる。 As a method of coating the resin on the carrier core material, for example, a spray drying method, a fluidized bed method, a spray drying method using a fluidized bed, an immersion method, or the like can be used. Among these, the fluidized bed method is particularly preferable in that it can be efficiently applied with a small amount of resin. For example, in the case of the fluidized bed method, the resin coating amount can be adjusted by the amount of resin solution sprayed and the spraying time.
キャリアの粒子径は、一般に、体積平均粒子径で１０μｍ〜２００μｍの範囲、特に２０μｍ〜６０μｍの範囲が好ましい。 The particle diameter of the carrier is generally preferably in the range of 10 μm to 200 μm, particularly 20 μm to 60 μm in terms of volume average particle diameter.
本発明に係る電子写真用現像剤は、以上のようにして作製したキャリアとトナーとを混合してなる。キャリアとトナーとの混合比に特に限定はなく、使用する現像装置の現像条件などから適宜決定すればよい。一般に現像剤中のトナー濃度は１質量％〜１５質量％の範囲が好ましい。トナー濃度が１質量％未満の場合、画像濃度が薄くなりすぎ、他方トナー濃度が１５質量％を超える場合、現像装置内でトナー飛散が発生し機内汚れや転写紙などの背景部分にトナーが付着する不具合が生じるおそれがあるからである。より好ましいトナー濃度は３質量％〜１０質量％の範囲である。 The electrophotographic developer according to the present invention is obtained by mixing the carrier prepared as described above and a toner. The mixing ratio of the carrier and the toner is not particularly limited, and may be determined as appropriate based on the developing conditions of the developing device to be used. Generally, the toner concentration in the developer is preferably in the range of 1% by mass to 15% by mass. When the toner density is less than 1% by mass, the image density becomes too low, while when the toner density exceeds 15% by mass, toner scattering occurs in the developing device, and the toner adheres to the background portion such as internal dirt or transfer paper. This is because there is a risk of malfunction. A more preferable toner concentration is in the range of 3% by mass to 10% by mass.
トナーとしては、重合法、粉砕分級法、溶融造粒法、スプレー造粒法など従来公知の方法で製造したものが使用できる。具体的には、熱可塑性樹脂を主成分とする結着樹脂中に、着色剤、離型剤、帯電制御剤等を含有させたものが好適に使用できる。 As the toner, toner produced by a conventionally known method such as a polymerization method, a pulverization classification method, a melt granulation method, or a spray granulation method can be used. Specifically, a binder resin containing a thermoplastic resin as a main component and containing a colorant, a release agent, a charge control agent and the like can be suitably used.
トナーの粒径は、一般に、コールターカウンターによる体積平均粒径で５μｍ〜１５μｍの範囲が好ましく、７μｍ〜１２μｍの範囲がより好ましい。 In general, the particle diameter of the toner is preferably in the range of 5 μm to 15 μm, more preferably in the range of 7 μm to 12 μm, as a volume average particle diameter measured by a Coulter counter.
トナー表面には、必要により、改質剤を添加してもよい。改質剤としては、例えば、シリカ、アルミナ、酸化亜鉛、酸化チタン、酸化マグネシウム、ポリメチルメタクリレート等が挙げられる。これらの１種又は２種以上を組み合わせて使用できる。 If necessary, a modifier may be added to the toner surface. Examples of the modifier include silica, alumina, zinc oxide, titanium oxide, magnesium oxide, polymethyl methacrylate and the like. These 1 type (s) or 2 or more types can be used in combination.
キャリアとトナーとの混合は、従来公知の混合装置を用いることができる。例えばヘンシェルミキサー、Ｖ型混合機、タンブラーミキサー、ハイブリタイザー等を用いることができる。 A known mixing device can be used for mixing the carrier and the toner. For example, a Henschel mixer, a V-type mixer, a tumbler mixer, a hybridizer, or the like can be used.
本発明の現像剤を用いた現像方法に特に限定はないが、磁気ブラシ現像法が好適である。図３に、磁気ブラシ現像を行う現像装置の一例を示す概説図を示す。図３に示す現像装置は、複数の磁極を内蔵した回転自在の現像ローラ３と、現像部へ搬送される現像ローラ３上の現像剤量を規制する規制ブレード６と、水平方向に平行に配置され、互いに逆向きに現像剤を撹拌搬送する２本のスクリュー１，２と、２本のスクリュー１，２の間に形成され、両スクリューの両端部において、一方のスクリューから他方のスクリューに現像剤の移動を可能とし、両端部以外での現像剤の移動を防ぐ仕切板４とを備える。 The developing method using the developer of the present invention is not particularly limited, but a magnetic brush developing method is preferable. FIG. 3 is a schematic diagram showing an example of a developing device that performs magnetic brush development. The developing device shown in FIG. 3 is arranged in parallel to a horizontal direction, and a rotatable developing roller 3 incorporating a plurality of magnetic poles, a regulating blade 6 for regulating the amount of developer on the developing roller 3 conveyed to the developing unit. Formed between the two screws 1 and 2 that stir and convey the developer in opposite directions and the two screws 1 and 2, and develops from one screw to the other at both ends of both screws. And a partition plate 4 that allows the developer to move and prevents the developer from moving except at both ends.
２本のスクリュー１，２は、螺旋状の羽根１３，２３が同じ傾斜角で軸部１１，２１に形成されたものであって、不図示の駆動機構によって同方向に回転し、現像剤を互いに逆方向に搬送する。そして、スクリュー１，２の両端部において一方のスクリューから他方のスクリューに現像剤が移動する。これによりトナーとキャリアからなる現像剤は装置内を常に循環し撹拌されることになる。 The two screws 1 and 2 have spiral blades 13 and 23 formed on the shaft portions 11 and 21 at the same inclination angle, and are rotated in the same direction by a drive mechanism (not shown) to remove the developer. Transport in opposite directions. The developer moves from one screw to the other screw at both ends of the screws 1 and 2. As a result, the developer composed of toner and carrier is constantly circulated and stirred in the apparatus.
一方、現像ローラ３は、表面に数μｍの凹凸を付けた金属製の筒状体の内部に、磁極発生手段として、現像磁極Ｎ１、搬送磁極Ｓ１、剥離磁極Ｎ２、汲み上げ磁極Ｎ３、ブレード磁極Ｓ２の５つの磁極を順に配置した固定磁石を有してなる。現像ローラ３が矢印方向に回転すると、汲み上げ磁極Ｎ３の磁力によって、スクリュー１から現像ローラ３へ現像剤が汲み上げられる。現像ローラ３の表面に担持された現像剤は、規制ブレード６により層規制された後、現像領域へ搬送される。 On the other hand, the developing roller 3 has, as a magnetic pole generating means, a developing magnetic pole N 1 , a transporting magnetic pole S 1 , a peeling magnetic pole N 2 , and a pumping magnetic pole N 3 inside a metal cylindrical body having a surface with a few μm unevenness. , comprising a fixed magnet disposed five pole blade pole S 2 in order. When the development roller 3 is rotated in the arrow direction, by the magnetic force of the magnetic pole N 3, the developer is pumped from the screw 1 to the developing roller 3. The developer carried on the surface of the developing roller 3 is regulated by the regulating blade 6 and then conveyed to the developing area.
現像領域では、直流電圧に交流電圧を重畳したバイアス電圧が転写電圧電源８から現像ローラ３に印加される。バイアス電圧の直流電圧成分は、感光体ドラム５表面の背景部電位と画像部電位との間の電位とされる。また、背景部電位と画像部電位とは、バイアス電圧の最大値と最小値との間の電位とされる。バイアス電圧のピーク間電圧は０．５〜５ｋＶの範囲が好ましく、周波数は１〜１０ｋＨｚの範囲が好ましい。またバイアス電圧の波形は矩形波、サイン波、三角波などいずれであってもよい。これによって、現像領域においてトナー及びキャリアが振動し、トナーが感光体ドラム５上の静電潜像に付着して現像がなされる。 In the developing region, a bias voltage obtained by superimposing an AC voltage on a DC voltage is applied from the transfer voltage power supply 8 to the developing roller 3. The DC voltage component of the bias voltage is a potential between the background portion potential on the surface of the photosensitive drum 5 and the image portion potential. Further, the background portion potential and the image portion potential are set to a potential between the maximum value and the minimum value of the bias voltage. The peak-to-peak voltage of the bias voltage is preferably in the range of 0.5 to 5 kV, and the frequency is preferably in the range of 1 to 10 kHz. The waveform of the bias voltage may be any of a rectangular wave, a sine wave, a triangular wave, and the like. As a result, the toner and the carrier vibrate in the development area, and the toner adheres to the electrostatic latent image on the photosensitive drum 5 and development is performed.
その後現像ローラ３上の現像剤は、搬送磁極Ｓ１によって装置内部に搬送され、剥離電極Ｎ２によって現像ローラ３から剥離して、スクリュー１，２によって装置内を再び循環搬送され、現像に供していない現像剤と混合撹拌される。本発明のキャリア芯材を用いた現像剤では、剥離電極Ｎ２による現像ローラ３からの剥離が円滑に行われる。そして汲み上げ極Ｎ３によって、新たに現像剤がスクリュー１から現像ローラ３へ供給される。これにより、画像濃度ムラが防止される。 Thereafter, the developer on the developing roller 3 is conveyed to the inside of the apparatus by the conveying magnetic pole S 1 , peeled off from the developing roller 3 by the peeling electrode N 2 , and circulated and conveyed again inside the apparatus by the screws 1 and 2 for development. Mix and stir with undeveloped developer. In the developer using the carrier core material of the present invention, peeling from the developing roller 3 by peeling the electrode N 2 it can be smoothly performed. Then, the developer is newly supplied from the screw 1 to the developing roller 3 by the pumping pole N 3 . Thereby, image density unevenness is prevented.
なお、図３に示した実施形態では現像ローラ３に内蔵された磁極は５つであったが、現像剤の現像領域での移動量を一層大きくしたり、汲み上げ性等を一層向上させるために、磁極を８極や１０極、１２極と増やしてももちろん構わない。 In the embodiment shown in FIG. 3, the number of magnetic poles built in the developing roller 3 is five. However, in order to further increase the amount of movement of the developer in the developing region, and to further improve the pumping performance and the like. Of course, the number of magnetic poles may be increased to 8 poles, 10 poles or 12 poles.
以下、本発明を実施例によりさらに詳しく説明するが本発明はこれらの例に何ら限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples at all.
実施例１
キャリア芯材を次のようにして作製した。Ｆｅを８．０ｍｏｌ、Ｔｉを０．１０ｍｏｌ、Ｓｒを０．１５ｍｏｌ及びＭｎ４．０ｍｏｌとなるようにＦｅ２Ｏ３、ＴｉＯ２、ＳｒＣＯ３及びＭｎ３Ｏ４を水に分散し、分散剤としてポリカルボン酸アンモニウム系分散剤を０．６ｗｔ％添加して混合物とした。この混合物の固形分濃度は７５ｗｔ％であった。この混合物を湿式ボールミル（メディア径２ｍｍ）により粉砕処理し、混合スラリーを得た。
Example 1
A carrier core material was produced as follows. Fe 2 O 3 , TiO 2 , SrCO 3 and Mn 3 O 4 are dispersed in water so that Fe is 8.0 mol, Ti is 0.10 mol, Sr is 0.15 mol and Mn is 4.0 mol. 0.6 wt% of an ammonium carboxylate dispersant was added to form a mixture. The solid content concentration of this mixture was 75 wt%. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry.
この混合スラリーをスプレードライヤーにて約１３０℃の熱風中に噴霧し、粒径１０〜７５μｍの乾燥造粒物を得た。この造粒物から、網目５４μｍの篩網を用いて粗粒を分離し、網目３３μｍの篩網を用いて微粒を分離した。 This mixed slurry was sprayed into hot air at about 130 ° C. with a spray dryer to obtain a dry granulated product having a particle size of 10 to 75 μm. From this granulated product, coarse particles were separated using a sieve mesh having a mesh size of 54 μm, and fine particles were separated using a sieve mesh having a mesh size of 33 μm.
この造粒物を、電気炉に投入し１１７０℃まで５時間かけて昇温した。その後１１７０℃で１５時間保持することにより焼成を行った。その後冷却速度２℃／分で５００℃まで冷却した。昇温段階及び焼成温度の保持段階での電気炉内の酸素濃度は１００００ｐｐｍ、冷却段階での酸素濃度は５０００ｐｐｍとなるよう、酸素と窒素とを混合したガスを炉内に供給した。 This granulated product was put into an electric furnace and heated to 1170 ° C. over 5 hours. Thereafter, firing was performed by holding at 1170 ° C. for 15 hours. Thereafter, it was cooled to 500 ° C. at a cooling rate of 2 ° C./min. A gas in which oxygen and nitrogen were mixed was supplied into the furnace so that the oxygen concentration in the electric furnace in the temperature raising stage and the firing temperature holding stage was 10,000 ppm, and the oxygen concentration in the cooling stage was 5000 ppm.
得られた焼成物をハンマーミルで解粒した後に振動ふるいを用いて分級し、体積平均粒径３４．９μｍの焼成物を得た。 The obtained fired product was pulverized with a hammer mill and classified using a vibration sieve to obtain a fired product having a volume average particle size of 34.9 μm.
次いで、得られた焼成物を大気雰囲気下４５０℃で１．５時間保持することにより酸化処理（高抵抗化処理）を行い、キャリア芯材を得た。 Next, the obtained fired product was subjected to an oxidation treatment (high resistance treatment) by holding at 450 ° C. for 1.5 hours in an air atmosphere to obtain a carrier core material.
得られたキャリア芯材の組成、形状特性、磁気特性、帯電特性などを後述の方法で測定した。測定結果を表２に示す。また、図１に、実施例１のキャリア芯材のＳＥＭ写真を示す。 The composition, shape characteristics, magnetic characteristics, charging characteristics and the like of the obtained carrier core material were measured by the methods described later. The measurement results are shown in Table 2. FIG. 1 shows an SEM photograph of the carrier core material of Example 1.
次に、このようにして得られたキャリア芯材の表面を樹脂で被覆してキャリアを作製した。具体的には、シリコーン樹脂４５０重量部と、（２−アミノエチル）アミノプロピルトリメトキシシラン９重量部とを、溶媒としてのトルエン４５０重量部に溶解してコート溶液を作製した。このコート溶液を、流動床型コーティング装置を用いてキャリア芯材５００００重量部に塗布し、温度３００℃の電気炉で加熱してキャリアを得た。以下、比較例についても同様にしてキャリアを得た。 Next, the surface of the carrier core material thus obtained was coated with a resin to prepare a carrier. Specifically, 450 parts by weight of a silicone resin and 9 parts by weight of (2-aminoethyl) aminopropyltrimethoxysilane were dissolved in 450 parts by weight of toluene as a solvent to prepare a coating solution. This coating solution was applied to 50000 parts by weight of a carrier core material using a fluid bed type coating apparatus and heated in an electric furnace at a temperature of 300 ° C. to obtain a carrier. Hereinafter, carriers were obtained in the same manner for the comparative examples.
得られたキャリアと体積平均粒径５．０μｍ程度のトナーとを、ポットミルを用いて所定時間混合し、二成分系の電子写真現像剤を得た。この場合、キャリアとトナーとをトナーの重量／（トナーおよびキャリアの重量）＝５／１００となるように調整した。以下、全ての比較例についても同様にして現像剤を得た。得られた現像剤について後述の実機評価を行った。評価結果を表２に示す。 The obtained carrier and a toner having a volume average particle size of about 5.0 μm were mixed for a predetermined time using a pot mill to obtain a two-component electrophotographic developer. In this case, the carrier and the toner were adjusted so that the weight of toner / (weight of toner and carrier) = 5/100. Hereinafter, the developer was obtained in the same manner for all the comparative examples. The obtained developer was evaluated on the actual machine described later. The evaluation results are shown in Table 2.
（実施例２）
焼成工程における電気炉温度を１２００℃に変更した以外は実施例１同様にして平均粒径３４．９μｍのキャリア芯材を作成した。
(Example 2)
A carrier core material having an average particle size of 34.9 μm was prepared in the same manner as in Example 1 except that the electric furnace temperature in the firing step was changed to 1200 ° C.
（実施例３）
Ｔｉを０．０５モル、Ｓｒを０．０８モルに変更した以外は実施例１同様にして平均粒径３４．８μｍのキャリア芯材を作成した。
(Example 3)
A carrier core material having an average particle size of 34.8 μm was prepared in the same manner as in Example 1 except that Ti was changed to 0.05 mol and Sr was changed to 0.08 mol.
（実施例４）
Ｔｉを０．４モル、Ｓｒを０．４モルに変更した以外は実施例１同様にして平均粒径３４．７μｍのキャリア芯材を作成した。
Example 4
A carrier core material having an average particle size of 34.7 μm was prepared in the same manner as in Example 1 except that Ti was changed to 0.4 mol and Sr was changed to 0.4 mol.
（実施例５）
Ｔｉを０．１５モル、Ｓｒを０．０８モルに変更した以外は実施例１同様にして平均粒径３４．６μｍのキャリア芯材を作成した。
(Example 5)
A carrier core material having an average particle diameter of 34.6 μm was prepared in the same manner as in Example 1 except that Ti was changed to 0.15 mol and Sr was changed to 0.08 mol.
（比較例１）
Ｔｉを０．０モル、Ｓｒを０．０６モル、焼成温度を１２００℃３時間保持、電気炉内の酸素濃度は１００００ｐｐｍ一定、冷却速度を４℃/分に変更した以外は実施例１同様にして平均粒径３４．６μｍのキャリア芯材を作成した。
(Comparative Example 1)
Example 1 except that Ti was 0.0 mol, Sr was 0.06 mol, the firing temperature was maintained at 1200 ° C. for 3 hours, the oxygen concentration in the electric furnace was constant at 10000 ppm, and the cooling rate was changed to 4 ° C./min. Thus, a carrier core material having an average particle diameter of 34.6 μm was prepared.
（比較例２）
Ｓｒを０．１５モルに変更した以外は比較例１同様にして平均粒径３４．３μｍのキャリア芯材を作成した。
(Comparative Example 2)
A carrier core material having an average particle diameter of 34.3 μm was prepared in the same manner as in Comparative Example 1 except that Sr was changed to 0.15 mol.
（比較例３）
Ｓｒを０．２１モルに変更した以外は比較例１同様にして平均粒径３４．２μｍのキャリア芯材を作成した。
(Comparative Example 3)
A carrier core material having an average particle diameter of 34.2 μm was prepared in the same manner as in Comparative Example 1 except that Sr was changed to 0.21 mol.
（比較例４）
Ｔｉを０．２４モル、Ｓｒを０．０８モルに変更した以外は実施例１同様にして平均粒径３３．８μｍのキャリア芯材を作成した。
(Comparative Example 4)
A carrier core material having an average particle size of 33.8 μm was prepared in the same manner as in Example 1 except that Ti was changed to 0.24 mol and Sr was changed to 0.08 mol.
（比較例５）
Ｆｅを８．０モル、Ｔｉを０．１０モル、Ｓｒを０．１５モル、Ｍｎ２．８モル、Ｍｇ１．２モルとなるようにＦｅ２Ｏ３、ＴｉＯ２、ＳｒＣＯ３、Ｍｎ３Ｏ４及びＭｇＯを用い、保持時間を４時間、電気炉内の酸素濃度は５０００ｐｐｍ一定にした以外は実施例１同様にして平均粒径３３．２μｍのキャリア芯材を作成した。
(Comparative Example 5)
Fe 2 O 3 , TiO 2 , SrCO 3 , Mn 3 O 4 and Fe so as to be 8.0 mol Fe, 0.10 mol Ti, 0.15 mol Sr, 2.8 mol Mn, 1.2 mol Mg A carrier core material having an average particle diameter of 33.2 μm was prepared in the same manner as in Example 1 except that MgO was used, the holding time was 4 hours, and the oxygen concentration in the electric furnace was kept constant at 5000 ppm.
（比較例６）
Ｔｉを０．２モルに変更した以外は比較例５同様にして平均粒径３３．８μｍのキャリア芯材を作成した。
(Comparative Example 6)
A carrier core material having an average particle diameter of 33.8 μm was prepared in the same manner as in Comparative Example 5 except that Ti was changed to 0.2 mol.
（組成分析）
（Ｆｅの分析）
鉄元素を含むキャリア芯材を秤量し、塩酸と硝酸の混酸水に溶解させた。この溶液を蒸発乾固させた後、硫酸水を添加して再溶解し過剰な塩酸と硝酸とを揮発させる。この溶液に固体Ａｌを添加して液中のＦｅ３＋を全てＦｅ２＋に還元する。続いて、この溶液中のＦｅ２＋イオンの量を過マンガン酸カリウム溶液で電位差滴定することにより定量分析し、Ｆｅ（Ｆｅ２＋）の滴定量を求めた。
（Ｍｎの分析）
キャリア芯材のＭｎ含有量は、ＪＩＳ Ｇ１３１１−１９８７記載のフェロマンガン分析方法（電位差滴定法）に準拠して定量分析を行った。本願発明に記載したキャリア芯材のＭｎ含有量は、このフェロマンガン分析方法（電位差滴定法）で定量分析し得られたＭｎ量である。
（Ｍｇの分析）
キャリア芯材のＭｇ含有量は、以下の方法で分析を行った。本願発明に係るキャリア芯材を酸溶液中で溶解し、ＩＣＰにて定量分析を行った。本願発明に記載したキャリア芯材のＭｇ含有量は、このＩＣＰによる定量分析で得られたＭｇ量である。
（Ｓｒの分析）
キャリア芯材のＳｒ含有量は、Ｍｇの分析同様にＩＣＰによる定量分析で行った。
（Ｔｉの分析）
キャリア芯材のＴｉ含有量は、Ｍｇの分析同様にＩＣＰによる定量分析で行った。
(Composition analysis)
(Analysis of Fe)
The carrier core material containing iron element was weighed and dissolved in a mixed acid water of hydrochloric acid and nitric acid. After evaporating this solution to dryness, sulfuric acid water is added and redissolved to volatilize excess hydrochloric acid and nitric acid. Solid Al is added to this solution to reduce all Fe 3+ in the solution to Fe 2+ . Subsequently, the amount of Fe 2+ ions in the solution was quantitatively analyzed by potentiometric titration with a potassium permanganate solution to obtain a titer of Fe (Fe 2+ ).
(Analysis of Mn)
The Mn content of the carrier core material was quantitatively analyzed according to the ferromanganese analysis method (potentiometric titration method) described in JIS G1311-1987. The Mn content of the carrier core material described in the present invention is the amount of Mn obtained by quantitative analysis by this ferromanganese analysis method (potentiometric titration method).
(Analysis of Mg)
The Mg content of the carrier core material was analyzed by the following method. The carrier core material according to the present invention was dissolved in an acid solution, and quantitative analysis was performed by ICP. The Mg content of the carrier core material described in the present invention is the amount of Mg obtained by this quantitative analysis by ICP.
(Sr analysis)
The Sr content of the carrier core material was determined by ICP quantitative analysis as in the case of Mg analysis.
(Analysis of Ti)
The Ti content of the carrier core material was measured by ICP quantitative analysis as in the case of Mg analysis.
（磁力の測定）
磁気的特性を示す磁化の測定については、ＶＳＭ（東英工業株式会社製、ＶＳＭ−Ｐ７）を用いて、飽和磁化σｓ及び磁化σ１ｋ、残留磁化σｒ、保磁力Ｈｃをそれぞれ測定した。
(Measurement of magnetic force)
About the measurement of the magnetization which shows a magnetic characteristic, saturation magnetization (sigma) s and magnetization (sigma) 1k , remanent magnetization (sigma) r, and coercive force Hc were measured using VSM (The Toei Industry Co., Ltd. make, VSM-P7).
（体積平均粒径）
キャリア芯材の体積平均粒径は、レーザー回折式粒度分布測定装置（日機装社製「マイクロトラックＭｏｄｅｌ９３２０−Ｘ１００」）を用いて測定した。
(Volume average particle size)
The volume average particle diameter of the carrier core material was measured using a laser diffraction particle size distribution measuring device (“Microtrack Model 9320-X100” manufactured by Nikkiso Co., Ltd.).
（Ｓｒフェライトの板状結晶が表面に析出している粒子個数割合）
得られた粒子について走査電子顕微鏡（日本電子社製）を用いて組成像、倍率１０００倍にて観察した。観察された粒子３００粒子の中から粒子表面にＦｅ−Ｓｒ−Ｏを成分とした板状の析出物が確認された粒子を、Ｓｒフェライトの板状結晶が粒界に析出している粒子として、１個としてカウントし、全測定数の内、その個数割合を算出した。図１に、倍率１０００倍での粒子観察ＳＥＭ写真を示す。このＳＥＭ写真において楕円で囲んだ部分が長方形状の結晶の析出が確認された部分である。Ｓｒフェライトの板状結晶は、粒子界面にあって、外形がほぼ長方形であることが多い。本発明にかかる偏析は、粒界に形成され、その形状は粒状の析出物と非相似形であり、明らかに軸比が異なる形状である。すなわち、板状結晶とは、倍率１０００倍での粒子観察ＳＥＭ像の視野において、当該視野において最大距離の長さ（μｍ）である最長と最短長さである最短（μｍ）との比であるアスペクト比 最長/最短で３以上を有するものである。また、板状結晶析出物が認められた部分をＥＤＳマッピング像で確認したところ、ＳｒとＦｅ成分が多く含まれている偏析であることがわかった。また、その他矩形で囲った粒状の析出物にはＳｒ及びＴｉ成分が多く含まれており、ＳｒＴｉＯ３系の析出物であることがわかった。
(Ratio of the number of particles on which Sr ferrite plate crystals are deposited)
The obtained particles were observed with a scanning electron microscope (manufactured by JEOL Ltd.) at a composition image and a magnification of 1000 times. Among the observed 300 particles, particles in which a plate-like precipitate containing Fe—Sr—O as a component was confirmed on the particle surface as particles in which plate crystals of Sr ferrite are precipitated at the grain boundaries. It counted as one and calculated the number ratio among all the measurement numbers. FIG. 1 shows a particle observation SEM photograph at a magnification of 1000 times. In this SEM photograph, the part enclosed by an ellipse is the part where precipitation of a rectangular crystal was confirmed. In many cases, the Sr ferrite plate-like crystal is at the grain interface and has a substantially rectangular outer shape. The segregation according to the present invention is formed at the grain boundary, and the shape thereof is dissimilar to the granular precipitate, and is clearly a shape having a different axial ratio. That is, the plate crystal is the ratio of the longest length (μm) to the shortest length (μm) in the field of view of the particle observation SEM image at a magnification of 1000 times. Aspect ratio The longest / shortest aspect ratio is 3 or more. Moreover, when the part by which the plate-shaped crystal precipitate was recognized was confirmed with the EDS mapping image, it turned out that it is a segregation which contains many Sr and Fe components. In addition, it was found that the granular precipitates enclosed by other rectangles contained a large amount of Sr and Ti components and were SrTiO 3 -based precipitates.
（算術平均粗さＲａの算出）
超深度カラー３Ｄ形状測定顕微鏡（ＶＫ−Ｘ１００、株式会社キーエンス製）を用い、１５０倍対物レンズで表面を観察して求めた。具体的には、まず表面の平坦な粘着テープにキャリア芯材の粒子を固定し、１５０倍対物レンズで測定視野を決定した後、オートフォーカス機能を用いて焦点を粘着テープ面に調整し、オート撮影機能を用いてキャリア芯材の粒子表面の３次元形状を取り込んだ。
(Calculation of arithmetic average roughness Ra)
Using an ultra-deep color 3D shape measurement microscope (VK-X100, manufactured by Keyence Corporation), the surface was observed with a 150 × objective lens. Specifically, the carrier core particles are first fixed on an adhesive tape with a flat surface, the measurement field of view is determined with a 150 × objective lens, and then the focus is adjusted to the adhesive tape surface using the autofocus function. The three-dimensional shape of the particle surface of the carrier core material was captured using the imaging function.
各パラメータの測定には、粒子粗さ検査ソフトウェア（三谷商事製）を用いて行った。まず、前処理として、得られたフェライト粒子の粒子認識と形状選別を行った。粒子認識は以下の方法で行った。撮影によって得られた３次元形状のうち、高さ方向の最大値を１００％、最小値を０％として最大値から最小値までの間を１００等分する。この１００〜３５％にあたる領域を抽出し、独立した領域の輪郭を粒子輪郭として認識した。次に形状選別で粗大、微小、会合などの粒子を除外した。この形状選別を行うことで以降に行う極率補正時の誤差を小さくすることができる。具体的には面積相当径２８μｍ以下、面積相当径３８μｍ以下、針状比１．１５以上に該当する粒子を除外した。ここで針状比とは粒子の最大長／対角幅の比から算出したパラメータであり、対角幅とは最大長に平行な２本の直線で粒子を挟んだときの２直線の最短距離を表す。
つぎに表面の３次元形状から解析に用いる部分の取り出しを行った。図２に、観察画面の概略図を示す。フェライト粒子の表面の中央部分に長さ１５．０μｍの水平方向に延びる線分３１を引き、その上下に０．７５μｍ間隔で１０本ずつ平行線を追加した場合の線分上にあたる粗さ曲線を、計２１本分取り出した。図２において、上側の１０本の線分３２ａ、下側の１０本の線分３２ｂを簡略的に示している。
The measurement of each parameter was performed using particle roughness inspection software (manufactured by Mitani Corporation). First, as a pretreatment, particle recognition and shape selection of the obtained ferrite particles were performed. Particle recognition was performed by the following method. Of the three-dimensional shape obtained by photographing, the maximum value in the height direction is 100%, the minimum value is 0%, and the range from the maximum value to the minimum value is equally divided into 100. The region corresponding to 100 to 35% was extracted, and the contour of the independent region was recognized as the particle contour. Next, coarse, fine, and association particles were excluded by shape selection. By performing this shape selection, it is possible to reduce an error at the time of correcting the polarities thereafter. Specifically, particles corresponding to an area equivalent diameter of 28 μm or less, an area equivalent diameter of 38 μm or less, and an acicular ratio of 1.15 or more were excluded. Here, the acicular ratio is a parameter calculated from the ratio of the maximum length / diagonal width of the particle, and the diagonal width is the shortest distance between the two straight lines when the particle is sandwiched between two straight lines parallel to the maximum length. Represents.
Next, the part used for analysis was extracted from the three-dimensional shape of the surface. FIG. 2 shows a schematic diagram of the observation screen. A roughness curve corresponding to the line segment when a line segment 31 having a length of 15.0 μm in the horizontal direction is drawn at the center of the surface of the ferrite particle and 10 parallel lines are added at intervals of 0.75 μm above and below the line segment 31. A total of 21 bottles were taken out. In FIG. 2, the upper ten line segments 32a and the lower ten line segments 32b are simply shown.
フェライト粒子は略球形状であるため、取り出した粗さ曲線は、バックグラウンドとして一定の曲率を持っている。このため、バックグラウンドの補正として、最適な二次曲線をフィッティングし、粗さ曲線から差し引く補正を行った。この場合ローパスフィルタを１．５μｍの強度で適用し、カットオフ値λを８０μｍとした。 Since the ferrite particles are substantially spherical, the extracted roughness curve has a certain curvature as the background. For this reason, as a background correction, an optimal quadratic curve was fitted and correction subtracted from the roughness curve was performed. In this case, a low-pass filter was applied with an intensity of 1.5 μm, and the cut-off value λ was 80 μm.
算術平均粗さＲａについては、粗さ曲線の絶対値の平均を示したものであり、以下の数式１に示す式によって求められる。 The arithmetic average roughness Ra indicates the average of the absolute values of the roughness curve, and is obtained by the following equation (1).
算術平均粗さＲａについては、ＪＩＳ Ｂ０６０１（２００１年度版）に準拠して行われるものである。
また、解析に用いるキャリア芯材の平均粒子径については３２〜３４μｍに限定した。このように測定対象となるキャリア芯材の平均粒子径を狭い範囲に限定することで、曲率補正の際に生じる残渣による誤差を小さくすることができる。
なお、パラメータの平均値として、３００粒子の平均値を用いることとした。
The arithmetic average roughness Ra is performed in accordance with JIS B0601 (2001 edition).
Moreover, about the average particle diameter of the carrier core material used for an analysis, it limited to 32-34 micrometers. In this way, by limiting the average particle diameter of the carrier core material to be measured to a narrow range, it is possible to reduce an error due to a residue generated during curvature correction.
The average value of 300 particles was used as the average value of the parameters.
（帯電量）
キャリア芯材９．５ｇ、市販のフルカラー機のトナー０．５ｇを１００ｍｌの栓付きガラス瓶に入れ、２５℃、相対湿度５０％の環境下で１２時間放置して調湿する。調湿したキャリア芯材とトナーを振とう器で１５分間振とうさせ混合する。ここで、振とう器については、株式会社ヤヨイ製のＮＥＷ−ＹＳ型を用い、１２６回／分、角度６０°で行った。撹拌１５分後の電子写真現像剤を３００ｍｇ採取し、ユーテック社製のＥＡ０２と自動吸引装置を用い、吸引圧力Ｈｉｇｈ、分離用メッシュをＳＵＳ製の７９５ｍｅｓｈ、トナーの捕集器具をフィルターカプセル（ユーテック社製ＥＡ０１０Ｃ）として９０秒吸引後の帯電量を測定した。同一サンプルについて２回の測定を行い、これらの平均値をキャリア芯材の帯電量とした。キャリア芯材の帯電量は下記式から算出した。なお、測定環境は、温度２５℃、相対湿度５０％とした。
帯電量（μＣ／ｇ）＝実測電荷（μＣ）÷トナー重量
（式中、トナー重量＝フィルターカプセル吸引後重量（ｇ）−フィルターカプセル吸引前重量（ｇ））
(Charge amount)
9.5 g of carrier core material and 0.5 g of commercially available full-color toner are put into a 100 ml stoppered glass bottle and left to stand for 12 hours in an environment of 25 ° C. and 50% relative humidity to adjust the humidity. The conditioned carrier core material and toner are shaken for 15 minutes with a shaker and mixed. Here, about the shaker, it carried out at 126 times / minute and the angle of 60 degrees using the NEW-YS type | mold made from Yayoi Co., Ltd. Collect 300 mg of electrophotographic developer after 15 minutes of stirring, use EA02 made by U-Tech and automatic suction device, suction pressure High, mesh for separation is 795 mesh made by SUS, and toner collection device is filter capsule (U-Tech) As EA010C), the charge amount after suction for 90 seconds was measured. The same sample was measured twice, and the average value of these was taken as the charge amount of the carrier core material. The charge amount of the carrier core material was calculated from the following formula. The measurement environment was a temperature of 25 ° C. and a relative humidity of 50%.
Charge amount (μC / g) = Measured charge (μC) ÷ Toner weight (where toner weight = weight after filter capsule suction (g) −weight before filter capsule suction (g))
（包絡係数）
走査型電子顕微鏡（日本電子製「ＪＳＭ−６５１０ＬＡ」）を用いて、加速電圧は５ｋＶ、スポットサイズは４５，倍率は４５０倍として、粒子が重ならないように撮影した。その画像情報を、インターフェースを介してメディアサイバネティクス社製画像解析ソフト(Ｉｍａｇｅ−Ｐｒｏ ＰＬＵＳ)に導入して解析を行い、粒子の周囲長及び粒子の包絡線の長を求め、前記式（１）より包絡係数Ｅを算出した。また、包絡係数Ｅは、１粒子毎に算出し、３００粒子の平均値を算出した。
(Envelope coefficient)
Using a scanning electron microscope (“JSM-6510LA” manufactured by JEOL Ltd.), the acceleration voltage was 5 kV, the spot size was 45, and the magnification was 450 times so that the particles were not overlapped. The image information is introduced into the image analysis software (Image-Pro PLUS) manufactured by Media Cybernetics via the interface and analyzed, and the perimeter of the particle and the length of the envelope of the particle are obtained. From the above equation (1) An envelope coefficient E was calculated. The envelope coefficient E was calculated for each particle, and the average value of 300 particles was calculated.
（実機評価）
図３に示した構造の現像装置（現像ローラの周速度Ｖｓ：４０６ｍｍ／ｓｅｃ，感光体ドラムの周速度Ｖｐ：２０５ｍｍ／ｓｅｃ，感光体ドラム−現像ローラ間距離：０．３ｍｍ）に、作製した二成分現像剤を投入し、初期、１ｋ印刷後、１０ｋ印刷後にそれぞれ評価用画像を３枚印刷し、１枚当たり５カ所の濃度を反射濃度計（東京電色社製の型番ＴＣ−６Ｄ）を用いて測定し下記基準で評価した。
「◎」：濃度の濃淡差の最大が０．１未満であり、濃度ムラが視認できない。
「○」：濃度の濃淡差の最大が０．１以上０．２未満あり、濃度ムラが視認できない。
「△」：濃度の濃淡差の最大が０．２以上０．３未満あり、濃度ムラが視認できる。
「×」：濃度の濃淡差の最大が０．３以上であり、濃度ムラが視認でき使用できない。
(Actual machine evaluation)
The developing device having the structure shown in FIG. 3 (developing roller peripheral speed Vs: 406 mm / sec, photosensitive drum peripheral speed Vp: 205 mm / sec, photosensitive drum-developing roller distance: 0.3 mm) was produced. Two-component developer is added, and after the initial 1k printing and 10k printing, 3 images for evaluation are printed, and the density at 5 locations per sheet is measured by a reflection densitometer (model number TC-6D manufactured by Tokyo Denshoku Co., Ltd.). Was measured using the following criteria.
“A”: The maximum density difference is less than 0.1, and density unevenness cannot be visually recognized.
“◯”: The maximum density difference is not less than 0.1 and less than 0.2, and density unevenness cannot be visually recognized.
“Δ”: The maximum density difference is 0.2 or more and less than 0.3, and density unevenness is visible.
“×”: The maximum density difference is 0.3 or more, and density unevenness is visible and cannot be used.
実施例１〜５のキャリア芯材では、残留磁化σｒが０．９（Ａ・ｍ２／ｋｇ）以下と現像ローラからの剥離が容易なものとなり、１０ｋ印刷後でも画像濃度ムラは視認できなかった。また、帯電量は５２．０〜６１．０μＣ／ｇの範囲と所望の帯電付与性を有していた。 In the carrier core materials of Examples 1 to 5, the residual magnetization σr is 0.9 (A · m 2 / kg) or less and can be easily peeled off from the developing roller, and image density unevenness cannot be visually recognized even after 10k printing. It was. Further, the charge amount was in the range of 52.0 to 61.0 μC / g and had a desired charge imparting property.
これに対して、Ｔｉを添加しなかった比較例１〜３のキャリア芯材では、Ｓｒの添加量に比例して、Ｓｒフェライトの析出したフェライト粒子が３３個数％〜８３個数％と多くなり、残留磁化σｒも０．８〜４．２（Ａ・ｍ２／ｋｇ）と高くなった。このため、１０ｋ印刷後に画像濃度ムラが視認された。 On the other hand, in the carrier core materials of Comparative Examples 1 to 3 in which Ti was not added, the ferrite particles on which Sr ferrite precipitated increased in proportion to the amount of Sr added, from 33% to 83%, The remanent magnetization σr was also increased to 0.8 to 4.2 (A · m 2 / kg). For this reason, image density unevenness was visually recognized after 10k printing.
Ｔｉ／Ｓｒのｍｏｌ比が３．０と高かった比較例４のキャリア芯材では、粒子の凹凸化が進まず帯電量は４２．３μＣ／ｇと低く、１ｋ印刷後及び１０ｋ印刷後に画像濃度ムラが視認された。 In the carrier core material of Comparative Example 4 in which the Ti / Sr molar ratio was as high as 3.0, the unevenness of the particles did not progress and the charge amount was as low as 42.3 μC / g, and the image density unevenness after 1k printing and 10k printing Was visible.
ＭｎＭｇフェライト組成の比較例５，６のキャリア芯材では、所定量のＳｒ及びＴｉを添加しても粒子の凹凸化が進まず、帯電量は４５．３μＣ／ｇ及び４７．２μＣ／ｇと低く、１０ｋ印刷後に画像濃度ムラが視認された。 In the carrier core materials of Comparative Examples 5 and 6 having the MnMg ferrite composition, even when a predetermined amount of Sr and Ti was added, the unevenness of the particles did not progress, and the charge amount was as low as 45.3 μC / g and 47.2 μC / g. Image density unevenness was visually recognized after 10k printing.
本発明に係るキャリア芯材によれば、Ｓｒの添加による残留磁化の上昇を抑えながら粒子の凹凸化を図ることができ有用である。 The carrier core material according to the present invention is useful because it can make the unevenness of the particles while suppressing an increase in residual magnetization due to the addition of Sr.
３ 現像ローラ
５ 感光体ドラム
3 Developing roller 5 Photosensitive drum
Claims (8)
Ｔｉ／Ｓｒがｍｏｌ比で２．０以下であり、
Ｓｒフェライトの板状結晶が表面に析出しているフェライト粒子の個数割合が１０個数％以下であることを特徴とするキャリア芯材。 A carrier core material composed of ferrite particles containing Fe: 45 to 65 wt%, Mn: 15 to 30 wt%, Sr: 0.1 to 5.0 wt%, Ti: 0.1 to 2.5 wt%, ,
Ti / Sr is 2.0 or less in mol ratio,
A carrier core material, wherein the number ratio of ferrite particles on which Sr ferrite plate-like crystals are precipitated is 10% by number or less.
１個粒子の算術平均粗さＲａが０．１μｍ以下であるフェライト粒子の個数割合が１０個数％以下である請求項１記載のキャリア芯材。 Arithmetic mean roughness Ra is 0.3 μm or more,
The carrier core material according to claim 1, wherein the number ratio of ferrite particles in which the arithmetic average roughness Ra of one particle is 0.1 μm or less is 10% by number or less.
Ｅ＝［（Ｌ１−Ｌ２）／Ｌ２］×１００ ・・・・・・（１）
（式中、Ｌ１はキャリア芯材投影像の外周長を表し、Ｌ２はキャリア芯材投影像の包絡線の長さを表す。） The carrier core material according to any one of claims 1 to 4, wherein an envelope coefficient E calculated from the following formula (1) is 6.0 or more.
E = [(L1-L2) / L2] × 100 (1)
(In the formula, L1 represents the outer peripheral length of the carrier core material projection image, and L2 represents the length of the envelope of the carrier core material projection image.)
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| JP2016200669A (en) * | 2015-04-08 | 2016-12-01 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material and method for forming the material |
| EP3492989A1 (en) * | 2017-11-29 | 2019-06-05 | Powdertech Co., Ltd. | Ferrite carrier core material for electrophotographic developer, carrier for electrophotographic developer, and developer |
| JP2020024274A (en) * | 2018-08-07 | 2020-02-13 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
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| JP6929086B2 (en) * | 2017-02-28 | 2021-09-01 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
| JP7116530B2 (en) * | 2017-03-16 | 2022-08-10 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material, electrophotographic development carrier and electrophotographic developer using the same |
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| JP3960606B2 (en) * | 2003-09-29 | 2007-08-15 | 株式会社リコー | Electrostatic latent image developer carrier, manufacturing method thereof, electrostatic latent image developer and process cartridge using the carrier |
| JP5541598B2 (en) * | 2010-10-21 | 2014-07-09 | パウダーテック株式会社 | Ferrite carrier core material for electrophotographic developer, ferrite carrier for electrophotographic developer, and electrophotographic developer using the ferrite carrier for electrophotographic developer |
| JP5650773B2 (en) * | 2013-02-25 | 2015-01-07 | Ｄｏｗａエレクトロニクス株式会社 | Method for producing carrier core material for electrophotographic developer, carrier core material for electrophotographic developer, carrier for electrophotographic developer, and electrophotographic developer |
| JP5692766B1 (en) * | 2014-01-20 | 2015-04-01 | パウダーテック株式会社 | Ferrite carrier core material and ferrite carrier for electrophotographic developer using ferrite particles having outer shell structure, and electrophotographic developer using the ferrite carrier |
| JP6277813B2 (en) * | 2014-03-24 | 2018-02-14 | 富士ゼロックス株式会社 | Electrostatic image developing carrier, electrostatic image developer, developer cartridge, process cartridge, and image forming apparatus |
| JP5839639B1 (en) * | 2014-07-29 | 2016-01-06 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core |
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| EP3492989A1 (en) * | 2017-11-29 | 2019-06-05 | Powdertech Co., Ltd. | Ferrite carrier core material for electrophotographic developer, carrier for electrophotographic developer, and developer |
| US11150569B2 (en) | 2017-11-29 | 2021-10-19 | Powdertech Co., Ltd. | Ferrite carrier core material for electrophotographic developer, carrier for electrophotographic developer, and developer |
| JP2020024274A (en) * | 2018-08-07 | 2020-02-13 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
| JP7099902B2 (en) | 2018-08-07 | 2022-07-12 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material |
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