JP2018155827A - Carrier core material, and carrier for electrophotographic development and developer for electrophotography using the same - Google Patents
Carrier core material, and carrier for electrophotographic development and developer for electrophotography using the same Download PDFInfo
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Abstract
Description
本発明は、キャリア芯材並びにこれを用いた電子写真現像用キャリア及び電子写真用現像剤に関するものである。 The present invention relates to a carrier core material, an electrophotographic developer carrier and an electrophotographic developer using the same.
例えば、電子写真方式を用いたファクシミリやプリンター、複写機などの画像形成装置では、感光体の表面に形成された静電潜像にトナーを付着させて可視像化し、この可視像を用紙等に転写した後、加熱・加圧して定着させている。高画質化やカラー化の観点から、現像剤としては、キャリアとトナーとを含むいわゆる二成分現像剤が広く使用されている。 For example, in 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, etc., it is 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上から剥離し、現像装置内で再びトナーと混合される。このため、キャリアの特性として、磁気ブラシを形成する磁気特性及び所望の電荷をトナーに付与する帯電特性が要求される。このようなキャリアとしては、マグネタイトや各種フェライト等からなるキャリア芯材の表面を樹脂で被覆した、いわゆるコーティングキャリアがこれまで多く用いられていた。また、コーティングキャリアに用いられていたこれまでのキャリア芯材は真球状であった。 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. As such a carrier, a so-called coating carrier in which the surface of a carrier core material made of magnetite, various ferrites or the like is coated with a resin has been widely used. Further, the carrier core material used so far for the coating carrier has a spherical shape.
近年、画像形成装置における画像形成速度の高速化という市場要求に対応するため、現像ローラの回転速度を速めて、現像領域への現像剤の単位時間当たりの供給量を増加させる傾向にある。 In recent years, in order to meet the market demand for higher image forming speed in image forming apparatuses, the rotation speed of the developing roller tends to be increased to increase the amount of developer supplied per unit time to the developing area.
ところが、真球状のキャリア芯材を用いたコーティングキャリアでは、現像領域へのトナー供給が不十分となり画像濃度が低下する不具合があった。例えば、現像ローラの１周前の画像の影響を受けて画像濃度が低下する現像メモリーと呼ばれる不具合があった。 However, the coating carrier using the spherical carrier core material has a problem that the toner density to the developing area is insufficient and the image density is lowered. For example, there is a problem called a development memory in which the image density decreases due to the influence of the image one round before the development roller.
そこで、キャリア芯材の表面を凹凸形状としたり、キャリア芯材の形状を異形化することで、感光体表面との摩擦抵抗及びキャリア同士の摩擦抵抗を大きくし、現像領域へのトナー供給量を増加させる技術が提案されている（例えば、特許文献１，２など）。 Therefore, by making the surface of the carrier core material uneven, or by making the shape of the carrier core material irregular, the frictional resistance with the surface of the photoreceptor and the frictional resistance between the carriers are increased, and the amount of toner supplied to the development area is increased. Techniques for increasing the number have been proposed (for example, Patent Documents 1 and 2).
しかしながら、キャリア芯材表面を凹凸形状にしただけでは、キャリア芯材表面を樹脂被覆した際に凹部にコート樹脂が厚く成膜されるため、コーティングキャリアの表面凹凸が不十分となりトナー保持性が未だ不十分である。また異形キャリアとして、不等多角形状や塊状のキャリアが提案されているが、球形状を逸脱した極端な異形化により、粒子同士の引っかかりなどが強くなって磁気ブラシが硬くなり、磁気ブラシで感光体表面が摺擦されることによって感光体表面が傷つけられるおそれがある。 However, if the surface of the carrier core material is made uneven only, the coating resin is thickly formed in the recesses when the surface of the carrier core material is coated with resin. It is insufficient. In addition, unequal polygonal and massive carriers have been proposed as irregularly shaped carriers. However, due to extreme irregularities that deviate from the spherical shape, the magnetic brushes become harder and harder, and the magnetic brushes become photosensitive. The surface of the photoconductor may be damaged by rubbing the surface of the photoconductor.
そこで本出願人は、現像領域へのトナー供給量を増加させることができ、しかも磁気ブラシによって感光体表面が傷つけられることのないキャリア芯材を提案した（特許文献３）。 Therefore, the present applicant has proposed a carrier core material that can increase the amount of toner supplied to the development area and that does not damage the surface of the photoreceptor by the magnetic brush (Patent Document 3).
現在、画像形成速度のさらなる高速化が開発検討されているところ、キャリア芯材においてもこのような高速化に対応したものが望まれている。 Currently, further development of image forming speed is under development, and a carrier core material corresponding to such high speed is desired.
そこで、本発明の目的は、より多くのトナーを現像領域に供給することができ、画像形成速度がより高速化した場合であっても現像メモリーなどの不具合が生じることがなく、しかも細線再現性といった画質の向上が図れるキャリア芯材を提供することにある。 Therefore, an object of the present invention is to supply more toner to the developing area, and even when the image forming speed is increased, there is no problem such as development memory, and fine line reproducibility. An object of the present invention is to provide a carrier core material that can improve the image quality.
また本発明の他の目的は、長期間の使用においても安定して良好な画質画像を形成することができる電子写真現像用キャリア及び電子写真用現像剤を提供することにある。 Another object of the present invention is to provide an electrophotographic developer carrier and an electrophotographic developer capable of stably forming a good image quality even after long-term use.
本発明によれば、組成式ＭＸＦｅ３−ＸＯ４（但し、ＭはＭｇ，Ｍｎ，Ｃａ，Ｔｉ，Ｃｕ，Ｚｎ，Ｓｒ，Ｎｉからなる群より選ばれる少なくとも１種の金属，０＜Ｘ＜１）で表されるフェライト粒子からなるキャリア芯材であって、球形粒子が２個以上の結合した結合粒子が２１個数％〜６０個数％含まれ、磁場７９．５８×１０３Ａ／ｍ（１０００エルステッド）を印加した際の磁化σ１ｋが４０Ａｍ２／ｋｇ以上６３Ａｍ２／ｋｇ以下であることを特徴とするキャリア芯材が提供される。 According to the present invention, the composition formula M X Fe 3-X O 4 (where M is at least one metal selected from the group consisting of Mg, Mn, Ca, Ti, Cu, Zn, Sr, Ni, 0 < A carrier core material composed of ferrite particles represented by X <1), which contains 21% to 60% by number of bonded particles in which two or more spherical particles are bonded, and has a magnetic field of 79.58 × 10 3 A / There is provided a carrier core material characterized in that the magnetization σ 1k when m (1000 oersted) is applied is 40 Am 2 / kg or more and 63 Am 2 / kg or less.
なお、結合粒子の含有率及び磁化σ１ｋの測定方法は後述する。また、本明細書において示す「〜」は、特に断りのない限り、その前後に記載の数値を下限値及び上限値として含む意味で使用する。 In addition, the measuring method of the content rate of coupling | bonding particle | grains and magnetization (sigma) 1k is mentioned later. In addition, unless otherwise specified, “˜” shown in the present specification is used in the sense of including the numerical values described before and after it as the lower limit value and the upper limit value.
前記構成のキャリア芯材において、キャリア芯材の体積平均粒径（以下、単に「平均粒径」と記すことがある。）は２５μｍ以上５０μｍ未満であるのが好ましい。 In the carrier core material configured as described above, the carrier core material preferably has a volume average particle diameter (hereinafter sometimes simply referred to as “average particle diameter”) of 25 μm or more and less than 50 μm.
前記構成のキャリア芯材において、前記結合粒子以外の通常粒子の表面の最大山谷深さＲｚが１．２μｍ以上２．２μｍ以下であるのが好ましい。なお、粒子表面の最大山谷深さＲｚの測定方法は後述する。 In the carrier core material configured as described above, it is preferable that the maximum peak / valley depth Rz on the surface of normal particles other than the binding particles is 1.2 μm or more and 2.2 μm or less. A method for measuring the maximum valley depth Rz on the particle surface will be described later.
また、本発明によれば、前記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（以下、単に「キャリア」と記すことがある。）が提供される。 In addition, according to the present invention, there is provided an electrophotographic developing carrier (hereinafter sometimes simply referred to as “carrier”), wherein the surface of the carrier core material described above is coated with a resin. The
さらに、本発明によれば、前記記載の電子写真現像用キャリアとトナーとを含む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 electrophotographic developer carrier described above and a toner.
本発明に係るキャリア芯材によれば、より多くのトナーを現像領域に供給することができ、画像形成速度がより高速化した場合であっても現像メモリーなどの不具合が防止される。また、現像ローラ上に形成される磁気ブラシが柔軟なものとなり細線再現性といった画質が向上すると共に現像装置における撹拌トルクが小さくなる。これにより、本発明に係るキャリア芯材を含む現像剤を用いれば、長期間の使用においても安定して良好な画質画像を形成することができる。 According to the carrier core material of the present invention, more toner can be supplied to the development area, and problems such as development memory can be prevented even when the image forming speed is further increased. In addition, the magnetic brush formed on the developing roller is flexible, improving the image quality such as fine line reproducibility and reducing the stirring torque in the developing device. Thereby, if the developer containing the carrier core material according to the present invention is used, a good image quality can be stably formed even for a long period of use.
本出願人は、数個のフェライト球形粒子が結合した結合粒子をキャリア芯材中に所定の個数割合含有させることによって現像領域に多くのトナーを供給可能となる知見を得、既に出願した（特開２０１６−１６１７４１号公報等）。そして本発明者等は、今後の画像形成速度のさらなる高速化を見据えてより多くのトナーを現像領域に供給可能とするため、結合粒子をさらに高い割合で含有させることを検討した。しかし、結合粒子の含有割合を高くすると細線再現性などの画質の低下が生じやすくなるとの知見を得た。そこで本発明者等は、現像領域へのトナー供給量の増加と画質低下の抑制とを両立させるべく更に鋭意検討を重ねた結果、キャリア芯材における結合粒子の含有割合を高くするとともにキャリア芯材の磁化σ１ｋを所定範囲とすればよいことを見出し本発明を成すに至った。 The present applicant has obtained a knowledge that a large amount of toner can be supplied to the development region by including a predetermined number ratio of binding particles in which several ferrite spherical particles are bound in the carrier core material, and has already filed an application (special feature). No. 2006-161741). The inventors of the present invention have studied to contain a higher proportion of the binding particles in order to allow more toner to be supplied to the development region with a view to further increasing the image forming speed in the future. However, it has been found that when the content ratio of the binding particles is increased, the image quality such as fine line reproducibility tends to be deteriorated. Therefore, as a result of further intensive studies to achieve both an increase in the amount of toner supplied to the development area and a suppression of image quality degradation, the present inventors have increased the content ratio of the binder particles in the carrier core material and have increased the carrier core material. As a result, the inventors have found that the magnetization σ 1k may be within a predetermined range.
すなわち、本発明に係るキャリア芯材は、球形粒子が２個以上の結合した結合粒子が２１個数％以上６０個数％含まれ、磁化σ１ｋが４０Ａｍ２／ｋｇ以上６３Ａｍ２／ｋｇ以下であるフェライト粒子からなることを特徴とする。なお、本発明にかかる結合粒子以外の通常粒子は球形であるのが好ましい。 That is, the carrier core material according to the present invention contains 21% by number to 60% by number of bonded particles in which two or more spherical particles are bonded, and has a magnetization σ 1k of 40 Am 2 / kg or more and 63 Am 2 / kg or less. It consists of particles. The normal particles other than the binding particles according to the present invention are preferably spherical.
球形粒子が２個以上結合した、球形から大きく外れた異形な結合粒子がキャリア芯材中に所定の個数割合で含まれていると、通常粒子と結合粒子との間にトナーが取り込まれる空間が生じ得る。そして、通常粒子と結合粒子との間の空間に取り込まれたトナーは、現像ローラの回転によって現像領域に搬送されると共に、前記空間に取り込まれていたトナーが磁気ブラシの表面に現れ現像に寄与する。加えて、従来の不等多角形状や塊状のキャリアと異なって、本発明で使用する結合粒子は、球形粒子同士が結合した粒子であるため角部がない。このため、感光体表面を磁気ブラシで摺擦しても粒子の角部で感光体表面が傷つくことはない。 If the carrier core material contains a predetermined number of irregularly bonded particles that are greatly deviated from the spherical shape, in which two or more spherical particles are bonded, there is a space for toner to be taken in between the normal particles and the bonded particles. Can occur. The toner taken into the space between the normal particles and the binding particles is transported to the developing area by the rotation of the developing roller, and the toner taken into the space appears on the surface of the magnetic brush and contributes to the development. To do. In addition, unlike conventional unequal polygonal shapes or massive carriers, the bonded particles used in the present invention are particles in which spherical particles are bonded to each other, and thus have no corners. For this reason, even if the surface of the photoreceptor is rubbed with a magnetic brush, the surface of the photoreceptor is not damaged at the corners of the particles.
結合粒子を形成する球形粒子の各粒径に特に限定はないが、結合粒子としては粒径が最も大きい母粒子と、この母粒子よりも粒径の小さい子粒子とが結合したものが好ましい。さらには、少なくとも１つの子粒子の粒径が母粒子の粒径に対して１/４より大きい結合粒子が好ましい。このような結合粒子がキャリア芯材に所定割合で含まれていることで、トナーが取り込まれ得る通常粒子と結合粒子との間の空間及び結合粒子同士の空間が大きくなり、より多くのトナーが現像領域に搬送され、現像メモリーの発生が効果的に抑制されるようになる。 Each particle size of the spherical particles forming the binding particles is not particularly limited, but the binding particles are preferably those in which a mother particle having the largest particle size and a child particle having a smaller particle size than the mother particle are bonded. Furthermore, a bonded particle in which the particle size of at least one child particle is larger than 1/4 of the particle size of the mother particle is preferable. By including such binding particles in a predetermined ratio in the carrier core material, the space between the normal particles and the binding particles where the toner can be taken in and the space between the binding particles are increased, so that a larger amount of toner can be obtained. It is conveyed to the development area, and the occurrence of development memory is effectively suppressed.
なお、結合粒子は母粒子と子粒子とが結合部分を共有した形態で存在しているので、母粒子及び子粒子の粒径は、キャリア芯材の形状を走査電子顕微鏡（日本電子社製：ＪＳＭ−６５１０ＬＡ）を用いて倍率２５０倍で撮影した画像において、結合粒子の結合部分を除いた領域から粒子を球形近似することによりそれぞれ算出した。 In addition, since the binding particles exist in a form in which the base particles and the child particles share a binding portion, the particle size of the base particles and the child particles is determined by scanning electron microscope (manufactured by JEOL Ltd .: JSM-6510LA) was used to calculate each of the particles by spherical approximation from the region excluding the binding portion of the binding particles in an image taken at a magnification of 250 times.
本発明で使用する結合粒子において、母粒子と子粒子の組成は、同じであってもよいし異なっていてもよい。 In the bonded particles used in the present invention, the composition of the mother particles and the child particles may be the same or different.
このような結合粒子は、例えば、後述するキャリア芯材の製造工程において、焼成温度での保持時間を長くしたり、焼成後の解粒操作を調整することにより得ることができる。この方法によれば、キャリア芯材中の結合粒子の含有割合を容易に調整することできる。 Such a binding particle can be obtained, for example, by increasing the holding time at the firing temperature or adjusting the pulverization operation after firing in the carrier core manufacturing process described later. According to this method, the content ratio of the binding particles in the carrier core material can be easily adjusted.
あるいはまた、キャリア芯材の製造工程において、平均粒径の異なる造粒物を混合し焼成することにより得ることができる。この方法によれば、キャリア芯材中の結合粒子の含有割合を容易に調整することができ、同時に母粒子と子粒子の粒径を所望の粒径に容易に調整することができる。 Or it can obtain by mixing and baking the granulated material from which average particle diameter differs in the manufacturing process of a carrier core material. According to this method, the content ratio of the binding particles in the carrier core material can be easily adjusted, and at the same time, the particle sizes of the mother particles and the child particles can be easily adjusted to a desired particle size.
キャリア芯材における結合粒子の含有割合は２１個数％以上６０個数％以下である。結合粒子の含有割合が２１個数％未満であると、画像形成速度が速くなった場合には現像領域へのトナー供給量が不十分となることがある一方、結合粒子の含有割合が６０個数％を超えると、キャリア芯材の流動性が悪くなりすぎて磁気ブラシ内でのキャリアの循環移動が十分に行われず、画像形成速度が速くなった場合に十分な画像濃度が得られない。より好ましい結合粒子の含有割合は２２個数％以上５５個数％以下の範囲である。 The content ratio of the binder particles in the carrier core material is 21% by number or more and 60% by number or less. When the content ratio of the binding particles is less than 21% by number, the toner supply amount to the development area may be insufficient when the image forming speed is increased, while the content ratio of the binding particles is 60% by number. If it exceeds 1, the fluidity of the carrier core material becomes too poor, and the carrier is not sufficiently circulated and moved within the magnetic brush, and sufficient image density cannot be obtained when the image forming speed is increased. A more preferable content ratio of the binder particles is in a range of 22% by number to 55% by number.
本発明のキャリア芯材の磁化σ１ｋは４０Ａｍ２／ｋｇ以上６３Ａｍ２／ｋｇ以下の範囲である。本発明のキャリア芯材の磁化σ１ｋを前記範囲とすることによって、現像ローラ上に形成される磁気ブラシが柔軟なものとなり細線再現性といった画質が向上する。また、現像ローラの回転トルクも小さくなる。キャリア芯材の磁化σ１ｋの制御は、例えば、焼成工程における酸素濃度によって行うことができる。 Magnetization sigma 1k of the carrier core material of the present invention is in the range of less 40 Am 2 / kg or more 63Am 2 / kg. By setting the magnetization σ 1k of the carrier core material of the present invention in the above range, the magnetic brush formed on the developing roller becomes flexible and the image quality such as fine line reproducibility is improved. Further, the rotational torque of the developing roller is also reduced. The control of the magnetization σ 1k of the carrier core material can be performed by, for example, the oxygen concentration in the firing step.
本発明のキャリア芯材における前記結合粒子以外の通常粒子の表面の最大山谷深さＲｚは１．２μｍ以上２．２μｍ以下の範囲であるのが好ましい。通常粒子の表面の最大山谷深さＲｚが前記範囲であると、通常粒子同士の間に形成される空間も大きくなり、より多くのトナーがこの空間に取り込まれて現像領域へのトナー搬送量が増え、現像メモリーなどの画像不具合が一層抑制される。通常粒子の表面の最大山谷深さＲｚは、原料におけるＳｒ及びＣｌの含有量及び製造工程における焼結条件などによって調整することができる。詳細は後述する。 In the carrier core material of the present invention, the maximum peak / valley depth Rz of normal particles other than the binding particles is preferably in the range of 1.2 μm to 2.2 μm. When the maximum peak / valley depth Rz of the surface of the normal particles is within the above range, the space formed between the normal particles also becomes large, and a larger amount of toner is taken into this space and the amount of toner transported to the development area is increased. As a result, image defects such as development memory are further suppressed. The maximum peak / valley depth Rz of the surface of the normal particles can be adjusted by the contents of Sr and Cl in the raw material, the sintering conditions in the manufacturing process, and the like. Details will be described later.
本発明のキャリア芯材の体積平均粒径としては、２５μｍ以上５０μｍ未満の範囲が好ましく、より好ましくは３０μｍ以上４０μｍ以下の範囲である。 The volume average particle size of the carrier core material of the present invention is preferably in the range of 25 μm or more and less than 50 μm, more preferably in the range of 30 μm or more and 40 μm or less.
本発明のキャリア芯材を構成するフェライト粒子の組成に特に限定はなく、組成式ＭＸＦｅ３−ＸＯ４（但し、Ｍは、Ｍｇ，Ｍｎ，Ｃａ，Ｔｉ，Ｓｒ，Ｃｕ，Ｚｎ，Ｓｒ，Ｎｉからなる群より選択される少なくとも１種の金属元素、０＜Ｘ＜１）で表されるものが使用される。これらの中でも、一般式（ＭｎＯ）ｘ（ＭｇＯ）ｙ（Ｆｅ２Ｏ３）ｚで表され、ｘ，ｙ，ｚがそれぞれ４５ｍｏｌ％〜５５ｍｏｌ％，０〜２０ｍｏｌ％，３０ｍｏｌ％〜５０ｍｏｌ％であり、ＭｎＯ及び／又はＭｇＯの一部をＳｒＯで０．１５ｍｏｌ％〜１．０ｍｏｌ％置換したものが好ましい。 The composition of the ferrite particles constituting the carrier core material of the present invention is not particularly limited, and the composition formula M X Fe 3 -X O 4 (where M is Mg, Mn, Ca, Ti, Sr, Cu, Zn, Sr). , Ni, selected from the group consisting of at least one metal element selected from the group consisting of Ni and 0 <X <1). Among these, the general formula (MnO) x (MgO) y (Fe 2 O 3) is represented by z, x, y, z is 45mol% ~55mol% respectively, 0 to 20 mol%, a 30 mol% 50 mol% , MnO and / or MgO is preferably substituted by 0.15 mol% to 1.0 mol% with SrO.
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、Ｍ成分原料を秤量する。なお、ＭはＭｇ、Ｍｎ、Ｃａ、Ｔｉ、Ｃｕ、Ｓｒ、Ｚｎ、Ｎｉ等の２価の価数をとり得る金属元素から選ばれる少なくとも１種の金属元素である。Ｆｅ成分原料としては、Ｆｅ２Ｏ３等が好適に使用される。Ｍ成分原料としては、ＭｎであればＭｎＣＯ３、Ｍｎ３Ｏ４等が使用でき、ＭｇであればＭｇＯ、Ｍｇ（ＯＨ）２、ＭｇＣＯ３が好適に使用できる。また、Ｃａ成分原料としては、ＣａＯ、Ｃａ（ＯＨ）２、ＣａＣＯ３等から選択される少なくとも１種の化合物が好適に使用される。Ｓｒ成分原料としては、ＳｒＣＯ３、Ｓｒ（ＮＯ３）２などが好適に使用される。 First, the Fe component raw material and the M component raw material are weighed. M is at least one metal element selected from divalent metal elements such as Mg, Mn, Ca, Ti, Cu, Sr, Zn, and Ni. As the Fe component material, Fe 2 O 3 or the like is preferably used. As the M component raw material, MnCO 3 , Mn 3 O 4 and the like can be used for Mn, and MgO, Mg (OH) 2 and MgCO 3 can be suitably used for Mg. As the Ca component raw material, at least one compound selected from CaO, Ca (OH) 2 , CaCO 3 and the like is preferably used. As the Sr component raw material, SrCO 3 , Sr (NO 3 ) 2 or the like is preferably used.
ここで、フェライト粒子表面の最大山谷深さＲｚを制御するためにＳｒ及びＣｌ（塩素）を微量添加するのが望ましい。Ｓｒを微量添加することによって焼成工程においてＳｒフェライトが一部生成することにより、マグネトプランバイト型の結晶構造が形成されてフェライト粒子表面の凹凸形状が促進されやすくなる。Ｓｒの好適な添加量は、フェライト粒子の主成分１００ｍｏｌ％に対してＳｒＯ換算で０．３ｍｏｌ％〜１．５ｍｏｌ％の範囲である。また、Ｃｌ成分を微量添加することによって焼成工程においてガス化した塩化鉄が粒子表面において酸素と反応してマグネタイト（Ｆｅ３Ｏ４）が析出し粒子表面の凹凸が促進される。なお、Ｃｌ成分は、Ｆｅ成分原料等の原料中に不可避不純物として含有されていることがある。また必要により原料としてＨＣｌを添加する。 Here, it is desirable to add a small amount of Sr and Cl (chlorine) in order to control the maximum depth Rz of the ferrite particle surface. By adding a small amount of Sr, a part of Sr ferrite is generated in the firing step, so that a magnetoplumbite type crystal structure is formed and the uneven shape on the surface of the ferrite particles is easily promoted. A suitable addition amount of Sr is in the range of 0.3 mol% to 1.5 mol% in terms of SrO with respect to 100 mol% of the main component of the ferrite particles. Further, by adding a small amount of the Cl component, iron chloride gasified in the firing step reacts with oxygen on the particle surface to precipitate magnetite (Fe 3 O 4 ) and promote unevenness on the particle surface. The Cl component may be contained as an inevitable impurity in raw materials such as Fe component raw materials. If necessary, HCl is added as a raw material.
次いで、原料を分散媒中に投入しスラリーを作製する。本発明で使用する分散媒としては水が好適である。分散媒には、前記仮焼成原料の他、必要によりバインダー、分散剤等を配合してもよい。バインダーとしては、例えば、ポリビニルアルコールが好適に使用できる。バインダーの配合量としてはスラリー中の濃度が０．５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、造粒物中に粒子内細孔が少なく、焼成時の焼結不足を防ぐことができる。 Next, the raw material is charged into a dispersion medium to prepare 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 material, and it can prevent the sintering shortage at the time of baking.
なお、秤量した原料を混合し仮焼成し解粒した後、分散媒に投入しスラリーを作製してもよい。仮焼成の温度としては７５０℃〜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。 In addition, after mixing the weighed raw materials, pre-baking and pulverizing, it may be put into a dispersion medium to produce a slurry. 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, the amount of gas generation at the time of baking is small, and reaction between solids fully advances, 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.
次に、以上のようにして作製されたスラリーを湿式粉砕する。例えば、ボールミルや振動ミルを用いて所定時間湿式粉砕する。粉砕後の原材料の平均粒径は５μｍ以下が好ましく、より好ましくは１μｍ以下である。振動ミルやボールミルには、所定粒径のメディアを内在させるのがよい。メディアの材質としては、鉄系のクロム鋼や酸化物系のジルコニア、チタニア、アルミナなどが挙げられる。粉砕工程の形態としては連続式及び回分式のいずれであってもよい。粉砕物の粒径は、粉砕時間や回転速度、使用するメディアの材質・粒径などによって調整される。 Next, the slurry produced as described above is wet pulverized. For example, wet grinding is performed for a predetermined time using a ball mill or a vibration mill. The average particle diameter of the raw material after pulverization is preferably 5 μm or less, more preferably 1 μm or less. The vibration mill or ball mill preferably contains a medium having a predetermined particle diameter. Examples of the material of the media include iron-based chromium steel and oxide-based zirconia, titania, and alumina. As a form of a grinding | pulverization process, any of a continuous type and a batch type may be sufficient. The particle size of the pulverized product is adjusted depending on the pulverization time and rotation speed, the material and particle size of the media used, and the like.
そして、粉砕されたスラリーを噴霧乾燥させて造粒する。具体的には、スプレードライヤーなどの噴霧乾燥機にスラリーを導入し、雰囲気中へ噴霧することによって球形に造粒する。噴霧乾燥時の雰囲気温度は１００℃〜３００℃の範囲が好ましい。これにより、粒径１０μｍ〜２００μｍの球形の造粒物が得られる。次いで、得られた造粒物を振動篩を用いて分級し所定の粒径範囲の造粒物を作製する。 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 size of 10 μm to 200 μm is obtained. Next, the obtained granulated product is classified using a vibrating sieve to produce a granulated product having a predetermined particle size range.
このとき、篩分けられた粒径の大きい造粒物を母粒子として用い、粒径の小さい造粒物を子粒子として用いてもよい。このような操作によれば分級によっても母粒子及び子粒子の粒径を制御できる。 At this time, a sieved granulated product having a large particle size may be used as a mother particle, and a granulated product having a small particle size may be used as a child particle. According to such an operation, the particle sizes of the mother particles and the child particles can be controlled also by classification.
例えば、粒径４０μｍの母粒子と粒径２０μｍの子粒子を作製する場合には、目開き３８μｍのステンレス篩を用いて、まず造粒物を篩上と篩下とに分級する。そして、篩上となった造粒物を母粒子用の原料とする。一方、篩下となった造粒物をさらに目開き２５μｍのステンレス篩を用いて分級し、篩下となった造粒物を子粒子用の原料とする。 For example, when producing mother particles having a particle size of 40 μm and child particles having a particle size of 20 μm, a granulated product is first classified into a sieve top and a sieve bottom using a stainless sieve having an opening of 38 μm. And let the granulated material which became the sieve top be a raw material for mother particles. On the other hand, the granulated product that has been sieved is further classified using a stainless sieve having an opening of 25 μm, and the granulated product that has been sieved is used as a raw material for the child particles.
そして、所定割合で結合粒子が生じるように、母粒子用の造粒物原料と子粒子用の造粒物原料とを所定の割合で混合する。このようにして得られた混合原料の粒度分布は、通常の操作では得られない複数のピークが見られるか、あるいは異形な分布状態となる。混合後の原料は、混合操作により子粒子と母粒子とが仮の結合状態となるが、特に結合のための結合剤の必要はなく、後工程の焼結工程において母粒子と子粒子が隣接されるように混合すればよい。 Then, the granulated material for the mother particles and the granulated material for the child particles are mixed at a predetermined ratio so that the bonded particles are generated at a predetermined ratio. In the particle size distribution of the mixed raw material thus obtained, a plurality of peaks that cannot be obtained by normal operation are observed, or an irregular distribution state is obtained. In the mixed raw material, the child particles and the mother particles are temporarily bonded by the mixing operation, but there is no need for a binder for bonding, and the mother particles and the child particles are adjacent in the subsequent sintering process. What is necessary is just to mix.
次に、前記の造粒物を所定温度に加熱した炉に投入して、フェライト粒子を合成するための一般的な手法で焼成することにより、フェライト粒子を生成させる。焼成温度としては１１００℃〜１３００℃の範囲が好ましい。焼成温度が１１００℃未満であると、相変態が起こりにくくなるとともに焼結も進みにくくなる。また、焼成温度が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。結合粒子の含有割合は、焼成温度での保持時間によっても調整することができ、通常、保持時間を長くすると結合粒子の含有割合は増える。また、フェライト粒子中のＳｒフェライト生成により生じる、粒子表面の最大山谷深さＲｚも同様に、焼成温度での保持時間によっても調整することができ、通常、保持時間を長くすると最大山谷深さＲｚは増大する。保持時間としては３時間以上が好ましく、６時間以上がより好ましい。前記焼成温度に至るまでの昇温速度としては２５０℃／ｈ〜５００℃／ｈの範囲が好ましい。焼成工程における酸素濃度は１．１％〜５％の範囲に制御するのが好ましい。 Next, the granulated material is put into a furnace heated to a predetermined temperature and fired 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 less than 1100 ° C., it is difficult for phase transformation to occur and sintering does not proceed easily. On the other hand, if the firing temperature exceeds 1300 ° C., excessive grains may be generated due to excessive sintering. The content ratio of the binding particles can also be adjusted by the holding time at the firing temperature. Usually, when the holding time is increased, the content ratio of the binding particles increases. Similarly, the maximum peak / valley depth Rz on the particle surface caused by the formation of Sr ferrite in the ferrite particles can also be adjusted by the holding time at the firing temperature. Will increase. The holding time is preferably 3 hours or more, and more preferably 6 hours or more. The rate of temperature increase up to the firing temperature is preferably in the range of 250 ° C / h to 500 ° C / h. The oxygen concentration in the firing step is preferably controlled in the range of 1.1% to 5%.
このようにして得られた焼成物を解粒する。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。この解粒処理によっても、結合粒子の含有割合を調整することができる。すなわち、焼成物に与える衝撃力を強く、長くするほど、結合粒子の結合が解消され結合粒子の含有割合は減少する。 The fired product thus obtained is pulverized. 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. Also by this pulverization treatment, the content ratio of the binding particles can be adjusted. That is, the stronger the impact force applied to the fired product is, the longer the binding of the binding particles is eliminated and the content ratio of the binding particles decreases.
解粒処理後、必要により、粒径を所定範囲に揃えるため分級を行ってもよい。分級方法としては、風力分級や篩分級など従来公知の方法を用いることができる。また、風力分級機で１次分級した後、振動篩や超音波篩で粒径を所定範囲に揃えるようにしてもよい。さらに、分級工程後に、磁場選鉱機によって非磁性粒子を除去するようにしてもよい。フェライト粒子の平均粒径としては２５μｍ以上５０μｍ未満が好ましい。 After the pulverization treatment, classification may be performed, if necessary, in order to align the particle size within 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 average particle size of the ferrite particles is preferably 25 μm or more and less than 50 μm.
その後、必要に応じて、分級後のフェライト粒子を酸化性雰囲気中で加熱して、粒子表面に酸化被膜を形成してフェライト粒子の高抵抗化を図ってもよい（高抵抗化処理）。酸化性雰囲気としては大気雰囲気又は酸素と窒素の混合雰囲気のいずれでもよい。また、加熱温度は、２００℃〜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、体積平均粒径で２５μｍ以上５０μｍ未満の範囲、特に３０μｍ以上４０μｍ以下の範囲が好ましい。 The particle diameter of the carrier is generally preferably in the range of 25 μm or more and less than 50 μm, particularly 30 μm or more and 40 μm or less 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 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 power source 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。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。 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. Then, the developer is newly supplied from the screw 1 to the developing roller 3 by the pumping pole N 3 .
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.
（結合粒子の含有率及び粒径の測定方法）
結合粒子の含有率は、観測画像により測定可能である。観測画像による全観測粒子数から、結合粒子数との割合により個数％を求めれば良い。
キャリア芯材の形状を走査電子顕微鏡（日本電子社製：ＪＳＭ−６５１０ＬＡ）を用いて倍率２５０倍で撮影した。撮影した画像より４００粒子中で結合粒子の数をカウントし、上記４００粒子中に含まれる結合粒子の個数割合を結合粒子含有率とした。
ただし、当該画像において、粒径（最大長さ）が３μｍ以下の微小粒子は、粒子としてカウントはしない。これは、微小粒子は、原料粉の状態であるものか、何らかの理由で破損した粉であり、キャリア芯材としての機能が期待できない不純物である。なお、通常は極めて少数であり、無視できる量でなければならない。さらに、粒子の外縁が確認できる粒子をカウントの対象とする。画像は、粒子が単分散しているものを用い、粒子が重なり、結合粒子であるか判別できない場合は、同一粒子を拡大、または視角を変更し、確認することが望ましい。結合粒子であれば、結合粒子の重心点は、母粒子の重心点と異なるため、横転(回転)しやすく、画像では側面からの視野となり、観測しやすい。
なお、結合粒子は、球形粒子が２個以上結合した粒子とした。そして、結合粒子では球形粒子と球形粒子とが結合部分を共有した形態で存在しているので、それぞれの球形粒の粒径は、キャリア芯材の形状を走査電子顕微鏡（日本電子社製：ＪＳＭ−６５１０ＬＡ）を用いて倍率２５０倍で撮影した画像において、結合粒子の結合部分を除いた領域から粒子を球形近似することによりそれぞれ算出した。
(Measurement method of the content rate and particle size of the binding particles)
The content rate of the binding particles can be measured by an observation image. From the total number of observed particles in the observed image, the number% may be obtained by the ratio with the number of coupled particles.
The shape of the carrier core material was photographed at a magnification of 250 times using a scanning electron microscope (manufactured by JEOL Ltd .: JSM-6510LA). The number of binding particles in 400 particles was counted from the photographed image, and the ratio of the number of binding particles contained in the 400 particles was defined as the binding particle content.
However, in the image, fine particles having a particle size (maximum length) of 3 μm or less are not counted as particles. This is because the fine particles are in the form of raw material powder or are broken powder for some reason, and are an impurity that cannot be expected to function as a carrier core material. It is usually very small and must be negligible. Furthermore, the particles whose outer edges are confirmed can be counted. It is desirable to confirm the image by enlarging the same particle or changing the viewing angle when the image uses monodispersed particles and it is not possible to determine whether the particles overlap and are bound particles. In the case of a bound particle, the center of gravity of the bound particle is different from the center of gravity of the mother particle, so that it is easy to roll over (rotate), and in the image, the field of view from the side is easy to observe.
The bonded particles were particles in which two or more spherical particles were bonded. In the binding particles, since the spherical particles and the spherical particles exist in a form in which the binding portion is shared, the particle diameter of each spherical particle is determined by scanning electron microscope (manufactured by JEOL Ltd .: JSM). -6510LA), the image was calculated by approximating the particles in a spherical shape from the area excluding the binding portion of the binding particles.
以下、本発明を実施例によりさらに詳しく説明するが本発明はこれらの例に何ら限定されるものではない。 EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these examples at all.
実施例１
原料としてＦｅ２Ｏ３（平均粒径０．６μｍ）を１０．７５ｋｇ、Ｍｎ３Ｏ４（平均粒径２．０μｍ）を４．２５ｋｇとを水５．０ｋｇ中に分散し、分散剤としてポリカルボン酸アンモニウム系分散剤を９０ｇ、還元剤としてカーボンブラックを４５ｇ、ＳｉＯ２原料としてコロイダルシリカ（固形分濃度５０％）を３０ｇ、ＳｒＣＯ３を７０ｇ添加して混合物とした。このときの固形分濃度を測定したところ、７５重量％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。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１０〜２００μｍ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２５μｍの篩網を用いて母粒子用（平均粒径４３μｍ）および子粒子用（平均粒径２２μｍ）の造粒物に分級した。この母粒子用の造粒物を４０ｗｔ％、子粒子用の造粒物を６０ｗｔ％の割合で混合した後、酸素濃度が１３０００ｐｐｍに調整された窒素雰囲気の電気炉に投入し、１２４０℃で３時間焼成した。得られた焼結粉を解粒後、振動篩を用いて分級し、平均粒径３４．３μｍのキャリア芯材を得た。図１に実施例１のキャリア芯材のＳＥＭ写真を示す。
Example 1
10.75 kg of Fe 2 O 3 (average particle size 0.6 μm) and 4.25 kg of Mn 3 O 4 (average particle size 2.0 μm) are dispersed in 5.0 kg of water as raw materials, and poly is used as a dispersant. 90 g of an ammonium carboxylate-based dispersant, 45 g of carbon black as a reducing agent, 30 g of colloidal silica (solid content concentration 50%) as a SiO 2 raw material, and 70 g of SrCO 3 were added to obtain a mixture. When the solid content concentration at this time was measured, it was 75% by weight. This mixture was pulverized by a wet ball mill (media diameter 2 mm) to obtain a mixed slurry. 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 200 μm. From this granulated material, coarse particles are separated using a sieve mesh with a mesh size of 54 μm, and granulated for mother particles (average particle size 43 μm) and child particles (average particle size 22 μm) using a sieve mesh with a mesh size of 25 μm. Classified into things. This granulated product for mother particles was mixed at a rate of 40 wt% and the granulated product for child particles at a rate of 60 wt%, and then charged into an electric furnace in a nitrogen atmosphere in which the oxygen concentration was adjusted to 13000 ppm. Baked for hours. The obtained sintered powder was pulverized and then classified using a vibrating sieve to obtain a carrier core material having an average particle diameter of 34.3 μm. The SEM photograph of the carrier core material of Example 1 is shown in FIG.
実施例２
母粒子用の造粒物と子粒子用の造粒物の混合割合をそれぞれ、５０ｗｔ％および５０ｗｔ％とした以外は、実施例１と同様の方法で平均粒径３５．２μｍのキャリア芯材を得た。
Example 2
A carrier core material having an average particle diameter of 35.2 μm was prepared in the same manner as in Example 1 except that the mixing ratio of the granulated product for the mother particles and the granulated product for the child particles was 50 wt% and 50 wt%, respectively. Obtained.
実施例３
母粒子用の造粒物と子粒子用の造粒物の混合割合をそれぞれ、６０ｗｔ％および４０ｗｔ％とした以外は、実施例１と同様の方法で平均粒径３４．８μｍのキャリア芯材を得た。
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 the mixing ratio of the granulated product for the mother particles and the granulated product for the child particles was 60 wt% and 40 wt%, respectively. Obtained.
実施例４
焼成時の酸素濃度を３００００ｐｐｍとした以外は、実施例３と同様の方法で平均粒径３５．２μｍのキャリア芯材を得た。
Example 4
A carrier core material having an average particle size of 35.2 μm was obtained in the same manner as in Example 3 except that the oxygen concentration during firing was 30000 ppm.
比較例１
母粒子用の造粒物と子粒子用の造粒物の混合割合をそれぞれ、７０ｗｔ％および３０ｗｔ％とした以外は、実施例１と同様の方法で平均粒径３４．８μｍのキャリア芯材を得た。図２に比較例１のキャリア芯材のＳＥＭ写真を示す。
Comparative Example 1
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 the mixing ratio of the granulated product for the mother particles and the granulated product for the child particles was 70 wt% and 30 wt%, respectively. Obtained. FIG. 2 shows an SEM photograph of the carrier core material of Comparative Example 1.
比較例２
焼成時の酸素濃度を３０００ｐｐｍとした以外は、実施例３と同様の方法で平均粒径３４．５μｍのキャリア芯材を得た。
Comparative Example 2
A carrier core material having an average particle size of 34.5 μm was obtained in the same manner as in Example 3 except that the oxygen concentration during firing was 3000 ppm.
比較例３
母粒子用の造粒物と子粒子用の造粒物の混合割合をそれぞれ、９０ｗｔ％および１０ｗｔ％とした以外は、実施例１と同様の方法で平均粒径３４．８μｍのキャリア芯材を得た。
Comparative Example 3
A carrier core material having an average particle diameter of 34.8 μm was prepared in the same manner as in Example 1 except that the mixing ratio of the granulated product for the mother particles and the granulated product for the child particles was 90 wt% and 10 wt%, respectively. Obtained.
比較例４
焼成時の焼成温度を１０８０℃とした以外は、実施例３と同様の方法で平均粒径３４．８μｍのキャリア芯材を得た。
Comparative Example 4
A carrier core material having an average particle size of 34.8 μm was obtained in the same manner as in Example 3 except that the firing temperature during firing was 1080 ° C.
（平均粒径の測定方法）
キャリア芯材の平均粒径は、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。
(Measuring method of average particle size)
The average particle size of the carrier core material was measured using a laser diffraction type particle size distribution measuring device (“Microtrack Model 9320-X100” manufactured by Nikkiso Co., Ltd.).
（最大山谷深さＲｚの測定方法）
超深度カラー３Ｄ形状測定顕微鏡（「ＶＫ−Ｘ１００」株式会社キーエンス製）を用い、１００倍対物レンズで表面を観察して求めた。具体的には、まず、表面の平坦な粘着テープにキャリア芯材を固定し、１００倍対物レンズで測定視野を決定した後、オートフォーカス機能を用いて焦点を粘着テープ面に調整した。キャリア芯材を固定した平坦な粘着テープ面に対し、垂直方向（Ｚ方向）からレーザー光線を照射し、面のＸ方向Ｙ方向に走査した。また、表面からの反射光の強度が最大となった時のレンズの高さ位置をつなぎ合わせることでＺ方向のデータを取得した。これらＸ、ＹおよびＺ方向の位置データをつなぎ合わせキャリア芯材表面の３次元形状を得た。なお、キャリア芯材表面の３次元形状の取り込みにはオート撮影機能を用いた。
各パラメータの測定には、粒子粗さ検査ソフトウェア（三谷商事製）を用いて行った。まず、前処理として、得られたキャリア芯材表面の３次元形状の粒子認識と形状選別を行った。粒子認識は以下の方法で行った。撮影によって得られた３次元形状のうち、Ｚ方向の最大値を１００％、最小値を０％として最大値から最小値までの間を１００等分する。この１００〜３５％にあたる領域を抽出し、独立した領域の輪郭を粒子輪郭として認識した。次に形状選別で粗大、微小、会合などの粒子を除外した。この形状選別を行うことで以降に行う極率補正時の誤差を小さくすることができる。具体的には面積相当径２８μｍ以下、３８μｍ以上、針状比１．１５以上に該当する粒子を除外した。ここで針状比とは粒子の最大長／対角幅の比から算出したパラメータであり、対角幅とは最大長に平行な２本の直線で粒子を挟んだときの２直線の最短距離を表す。
つぎに表面の３次元形状から解析に用いる部分の取り出しを行った。まず上記の方法で認識した粒子輪郭から求められる重心を中心として一辺の長さが１５．０μｍの正方形を描く。描いた正方形の中に２１本の平行線を引き、その線分上にあたる粗さ曲線を２１本分取り出した。
(Measurement method of maximum mountain valley depth Rz)
Using an ultra-deep color 3D shape measurement microscope (“VK-X100” manufactured by Keyence Corporation), the surface was observed with a 100 × objective lens. Specifically, first, the carrier core material was fixed to a pressure-sensitive adhesive tape having a flat surface, the measurement field of view was determined with a 100 × objective lens, and then the focus was adjusted to the pressure-sensitive adhesive tape surface using an autofocus function. The flat adhesive tape surface to which the carrier core material was fixed was irradiated with a laser beam from the vertical direction (Z direction) and scanned in the X direction and Y direction of the surface. Also, data in the Z direction was acquired by connecting the height positions of the lenses when the intensity of the reflected light from the surface was maximized. The position data in the X, Y, and Z directions were connected to obtain a three-dimensional shape on the surface of the carrier core material. Note that an auto photographing function was used to capture the three-dimensional shape of the surface of the carrier core material.
The measurement of each parameter was performed using particle roughness inspection software (manufactured by Mitani Corporation). First, as pretreatment, three-dimensional shape particle recognition and shape selection on the surface of the obtained carrier core material were performed. Particle recognition was performed by the following method. Of the three-dimensional shape obtained by photographing, the maximum value in the Z direction is set to 100% and the minimum value is set to 0%. 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, 38 μm or more, 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. First, a square having a side length of 15.0 μm is drawn around the center of gravity obtained from the particle contour recognized by the above method. 21 parallel lines were drawn in the drawn square, and 21 roughness curves corresponding to the line segment were taken out.
キャリア芯材は略球形状であるため、取り出した粗さ曲線は、バックグラウンドとして一定の曲率を持っている。このため、バックグラウンドの補正として、最適な二次曲線をフィッティングし、粗さ曲線から差し引く補正を行った。この場合、ローパスフィルタを１．５μｍの強度で適用し、カットオフ値λを８０μｍとした。 Since the carrier core has a substantially spherical shape, 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.
最大山谷深さＲｚは、粗さ曲線の中で最も高い山の高さと最も深い谷の深さの和として求めた。以上説明した最大高さＲｚの測定は、ＪＩＳ Ｂ０６０１（２００１年度版）に準拠して行われるものである。最大高さＲｚの算出には、各パラメータの平均値として、５０粒子の平均値を用いることとした。 The maximum mountain valley depth Rz was obtained as the sum of the highest mountain height and the deepest valley depth in the roughness curve. The measurement of the maximum height Rz described above is performed according to JIS B0601 (2001 edition). In calculating the maximum height Rz, an average value of 50 particles was used as an average value of each parameter.
（磁気特性）
室温専用振動試料型磁力計（ＶＳＭ）（東英工業社製「ＶＳＭ−Ｐ７」）を用いて、外部磁場を０〜７９．５８×１０４Ａ／ｍ（１００００エルステッド）の範囲で１サイクル連続的に印加して、磁場７９．５８×１０３Ａ／ｍ（１，０００エルステッド）を印加した際の磁化σ１ｋ、飽和磁化σｓ、残留磁化σｒ、保磁力Ｈｃを測定した。
（流動度）
キャリア芯材の流動度はＪＩＳ Ｚ ２５０２に準拠して測定した。
(Magnetic properties)
Using a vibration sample type magnetometer (VSM) dedicated to room temperature (“VSM-P7” manufactured by Toei Kogyo Co., Ltd.), the external magnetic field ranges from 0 to 79.58 × 10 4 A / m (10000 Oersted) for one cycle. The magnetization σ 1k , saturation magnetization σ s , residual magnetization σ r , and coercive force H c when applying a magnetic field of 79.58 × 10 3 A / m (1,000 oersted) were measured.
(Fluidity)
The fluidity of the carrier core material was measured according to JIS Z 2502.
（画像メモリー）
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、全ての実施例、比較例についても同様にしてキャリアを得た。
(Image memory)
The surface of the obtained carrier core material 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 all of the examples and comparative examples.
得られたキャリアと平均粒径５．０μｍ程度のトナーとを、ポットミルを用いて所定時間混合し、二成分系の電子写真現像剤を得た。この場合、キャリアとトナーとをトナーの重量／（トナーおよびキャリアの重量）＝５／１００となるように調整した。以下、全ての実施例、比較例についても同様にして現像剤を得た。得られた現像剤を、図３に示す構造の現像装置（現像ローラの周速度Ｖｓ：８１２ｍｍ／ｓｅｃ，感光体ドラムの周速度Ｖｐ：４１０ｍｍ／ｓｅｃ，感光体ドラム−現像ローラ間距離：０．３ｍｍ）に投入し、感光体ドラムの長手方向にベタ画像部と非画像部とが隣り合い、その後は広い面積の中間調が続く画像を初期と２０万枚画像形成後に取得し、現像ローラ２周目の現像ローラ１周目のベタ画像が現像された領域とそうでない領域との画像濃度を反射濃度計（東京電色社製の型番ＴＣ−６Ｄ）を用いて測定し、その差を求め下記基準で評価した。結果を表１に合わせて示す。
「◎」：０．００３未満
「○」：０．００３以上０．００６未満
「△」：０．００６以上０．０２０未満
「×」：０．０２０以上
The obtained carrier and a toner having an average particle diameter 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, developers were obtained in the same manner for all of the Examples and Comparative Examples. The developer thus obtained was developed into a developing device having the structure shown in FIG. 3 (developing roller peripheral speed Vs: 812 mm / sec, photosensitive drum peripheral speed Vp: 410 mm / sec, photosensitive drum-developing roller distance: 0. 3 mm), an image in which a solid image portion and a non-image portion are adjacent to each other in the longitudinal direction of the photosensitive drum, and a halftone of a wide area thereafter is obtained after the initial and 200,000 sheets are formed, and the developing roller 2 Measure the image density between the area where the solid image on the first development roller of the circumference is developed and the area where it is not, using a reflection densitometer (Model No. TC-6D manufactured by Tokyo Denshoku Co., Ltd.), and determine the difference. Evaluation was made according to the following criteria. The results are shown in Table 1.
“◎”: Less than 0.003 “O”: 0.003 or more and less than 0.006 “Δ”: 0.006 or more and less than 0.020 “X”: 0.020 or more
（細線再現性）
図３に示した現像装置を評価機として、画像面積率５％の文字チャートを出力し、目視による判定を行うことで細線再現性の評価を行った。具体的には、画像上の細線再現性のレベルを次の４段階で評価した。なお、「○」評価が、現在実用化されている高性能な電子写真現像剤と同等のレベルであり、「○」評価以上を合格と判定した。
「◎」：非常に良好なレベル
「○」：良好なレベル
「△」：使用可能なレベル
「×」：使用不可能なレベル
(Fine line reproducibility)
Using the developing device shown in FIG. 3 as an evaluator, a character chart with an image area ratio of 5% was output, and the fine line reproducibility was evaluated by visual judgment. Specifically, the level of fine line reproducibility on the image was evaluated in the following four stages. The “◯” evaluation was equivalent to the high-performance electrophotographic developer that is currently in practical use, and the “○” evaluation or higher was determined to be acceptable.
“◎”: Very good level “○”: Good level “△”: Usable level “×”: Unusable level
結合粒子の含有率が５５．６個数％及び３１．６個数％と高く、且つ磁化σ１ｋが６２．２Ａｍ２／ｋｇ及び６２．８Ａｍ２／ｋｇである実施例１，２キャリア芯材では、現像メモリーは生じず、画質についても実使用上問題のない水準であった。また、結合粒子の含有率が２２．６個数％と実施例１，２のキャリア芯材よりも若干低く、磁化σ１ｋが６２．１Ａｍ２／ｋｇである実施例３キャリア芯材では、現像メモリー及び画質は実使用上問題のない水準であった。結合粒子の含有率が２２．９個数％で磁化σ１ｋが４２．７Ａｍ２／ｋｇと実施例１〜３よりも低い実施例４のキャリア芯材では、現像メモリーは実使用上問題のない水準であり画質は優れていた。 In Examples 1 and 2, the carrier core material in which the content of the binder particles is as high as 55.6% and 31.6% and the magnetization σ 1k is 62.2 Am 2 / kg and 62.8 Am 2 / kg, There was no development memory, and the image quality was at a level that was not problematic for practical use. Further, in Example 3 carrier core material in which the content ratio of the binder particles is 22.6% by weight and slightly lower than the carrier core materials of Examples 1 and 2, and the magnetization σ 1k is 62.1 Am 2 / kg, the development memory In addition, the image quality was at a level where there was no problem in practical use. In the carrier core material of Example 4 in which the content ratio of the binder particles is 22.9% by number and the magnetization σ 1k is 42.7 Am 2 / kg, which is lower than those of Examples 1 to 3, the development memory has a level at which there is no problem in practical use. The image quality was excellent.
これに対して、結合粒子の含有率が１７．８個数％と低い比較例１のキャリア芯材では実使用上問題のあるレベルの現像メモリーが生じた。また、磁化σ１ｋが７０．２Ａｍ２／ｋｇと高い比較例２のキャリア芯材では、画質が実使用上問題のあるレベルであった。結合粒子の含有率が７．２個数％とさらに低い比較例３のキャリア芯材と、結合粒子の含有率が１７．２個数％と低く最大山谷深さＲｚが１．０μｍと低い比較例４のキャリア芯材では完全に問題のあるレベルの現像メモリーが生じた。 On the other hand, the carrier core material of Comparative Example 1 having a binding particle content as low as 17.8% by number produced a development memory having a problem in practical use. Further, in the carrier core material of Comparative Example 2 where the magnetization σ 1k is as high as 70.2 Am 2 / kg, the image quality was at a level causing a problem in practical use. The carrier core material of Comparative Example 3 in which the content rate of the binding particles is 7.2% by weight and the Comparative Example 4 in which the content rate of the binding particles is as low as 17.2% by number and the maximum valley depth Rz is as low as 1.0 μm. The development of a completely problematic level of development memory was obtained with the carrier core material.
３ 現像ローラ
５ 感光体ドラム
3 Developing roller 5 Photosensitive drum
Claims (5)
球形粒子が２個以上の結合した結合粒子が２１個数％〜６０個数％含まれ、
磁場７９．５８×１０３Ａ／ｍ（１０００エルステッド）を印加した際の磁化σ１ｋが４０Ａｍ２／ｋｇ以上６３Ａｍ２／ｋｇ以下である
ことを特徴とするキャリア芯材。 Composition formula M X Fe 3 -X O 4 (where M is at least one metal selected from the group consisting of Mg, Mn, Ca, Ti, Cu, Zn, Sr, Ni, 0 <X <1) A carrier core material made of ferrite particles,
21% by number to 60% by number of bonded particles in which two or more spherical particles are combined are included,
A carrier core material having a magnetization σ 1k of 40 Am 2 / kg or more and 63 Am 2 / kg or less when a magnetic field of 79.58 × 10 3 A / m (1000 oersted) is applied.
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| JP2021051246A (en) * | 2019-09-26 | 2021-04-01 | Ｄｏｗａエレクトロニクス株式会社 | Carrier core material, electrophotographic development carrier using the same, and electrophotographic developer |
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