JP6650300B2 - Carrier core material - Google Patents
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- JP6650300B2 JP6650300B2 JP2016047937A JP2016047937A JP6650300B2 JP 6650300 B2 JP6650300 B2 JP 6650300B2 JP 2016047937 A JP2016047937 A JP 2016047937A JP 2016047937 A JP2016047937 A JP 2016047937A JP 6650300 B2 JP6650300 B2 JP 6650300B2
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- Developing Agents For Electrophotography (AREA)
Description
本発明はキャリア芯材並びにそ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, a carrier for electrophotographic development using the same, and a developer for electrophotography.
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、フェライト粒子から構成されるキャリア芯材の表面を絶縁性樹脂で被覆したいわゆるコーティングキャリアとトナーとを混合した二成分系現像剤によって、感光体表面に形成された静電潜像を可視像化している。 2. Description of the Related Art In an image forming apparatus such as a facsimile, a printer, and a copying machine using an electrophotographic method, two-component development in which a so-called coating carrier in which the surface of a carrier core material composed of ferrite particles is coated with an insulating resin and a toner is mixed. The electrostatic latent image formed on the photoreceptor surface is visualized by the agent.
ここで使用されるキャリア芯材には電気的特性と磁気的特性とが要求される。具体的には、高抵抗且つ高磁力であることが要求される。キャリア芯材の抵抗が低いと、トナーに対する帯電付与性が低下し、非画像部にトナーが付着するいわゆるカブリが発生しやすくなる。また、キャリア芯材の磁力が低いと、現像ローラへの吸着が弱くなりキャリア飛散が生じやすくなる。 The carrier core material used here is required to have electric characteristics and magnetic characteristics. Specifically, high resistance and high magnetic force are required. When the resistance of the carrier core material is low, the charge imparting property to the toner is reduced, and so-called fog in which the toner adheres to the non-image portion is easily generated. When the magnetic force of the carrier core material is low, the carrier is weakly attracted to the developing roller, and carrier scattering is likely to occur.
そこで、例えば特許文献１では、磁化、ＢＥＴ比表面積及び平均粒径が一定範囲にあり、かつ周囲長／包絡長の個数分布が特定範囲にあるフェライトキャリア芯材が提案されている。また、先行文献２では、Ｍｇ、Ｔｉ及びＦｅを一定量含有し、細孔容積、ピーク細孔径及び磁気特性が特定範囲にある多孔質フェライト芯材が提案されている。 Therefore, for example, Patent Literature 1 proposes a ferrite carrier core material in which the magnetization, the BET specific surface area, and the average particle size are in a certain range, and the number distribution of perimeter / envelope is in a specific range. Prior Document 2 proposes a porous ferrite core material containing fixed amounts of Mg, Ti, and Fe and having a specific range of a pore volume, a peak pore diameter, and magnetic properties.
しかしながら、いずれの提案技術でもキャリア芯材の抵抗と磁力は未だ十分とは言えず、更なる向上が望まれている。 However, the resistance and magnetic force of the carrier core material cannot be said to be sufficient in any of the proposed techniques, and further improvement is desired.
そこで本発明の目的は、一層の高抵抗且つ高磁力を有するキャリア芯材を提供することにある。 Accordingly, an object of the present invention is to provide a carrier core material having higher resistance and higher magnetic force.
また本発明の他の目的は、キャリア飛散やカブリといった不具合を招くことなく、安定して良好な画質の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にある。 Another object of the present invention is to provide a carrier for an electrophotographic developer and an electrophotographic developer capable of stably forming an image of good image quality without causing problems such as carrier scattering and fogging. is there.
前記目的を達成する本発明に係るキャリア芯材は、Ｔｉ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、残留磁化σｒ（Ａｍ２／ｋｇ）に対する保持力Ｈｃ（１０３／４π・Ａ／ｍ）の比率Ｈｃ／σｒが１１．０以上１３．０以下であることを特徴とする。 The carrier core material according to the present invention that achieves the above object is a carrier core material composed of ferrite particles containing Ti, and has a coercive force Hc (10 3 / 4π ·) against residual magnetization σr (Am 2 / kg). (A / m) is not less than 11.0 and not more than 13.0.
ここで、Ｔｉの含有量としては０．６質量％以上１．２質量％以下の範囲であるのが好ましい。 Here, the content of Ti is preferably in a range from 0.6% by mass to 1.2% by mass.
また、前記フェライト粒子はＭｎ及びＭｇの少なくとも一方の元素をさらに含有しているのが好ましい。 Preferably, the ferrite particles further contain at least one element of Mn and Mg.
そしてまた、前記フェライト粒子はＣａ、Ｓｒ、Ｂａの少なくとも１つの元素をさらに含有しているのが好ましい。 Further, it is preferable that the ferrite particles further contain at least one element of Ca, Sr, and Ba.
また本発明によれば、前記のいずれかに記載のキャリア芯材の表面が樹脂で被覆されていることを特徴とする電子写真現像用キャリアが提供される。 Further, according to the present invention, there is provided an electrophotographic developing carrier, wherein the surface of the carrier core material described in any of the 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。 Further, according to the present invention, there is provided an electrophotographic developer including the carrier for electrophotographic development and a toner.
本発明のキャリア芯材によれば所望の抵抗と磁力とが得られ、キャリア飛散及びカブリといった不具合が抑制される。 According to the carrier core material of the present invention, desired resistance and magnetic force can be obtained, and problems such as carrier scattering and fogging are suppressed.
また本発明の電子写真現像用キャリア及び電子写真用現像剤によれば、長期間の使用においてもキャリア飛散やカブリといった不具合を招くことなく、安定して良好な画質の画像を形成することができる。 Further, according to the electrophotographic developing carrier and the electrophotographic developing agent of the present invention, it is possible to stably form an image of good image quality without causing troubles such as carrier scattering and fogging even during long-term use. .
本発明者等は、フェライト粒子からなるキャリア芯材が所望の磁力を有し且つ高い帯電性を有することができないか鋭意検討を重ねたところ、フェライト粒子中の磁壁面積を適切な範囲に制御することで磁力の低下を抑えながら抵抗を高められることを見出した。 The present inventors have intensively studied whether the carrier core material made of ferrite particles has a desired magnetic force and high chargeability, and controls the domain wall area in the ferrite particles to an appropriate range. It has been found that the resistance can be increased while suppressing a decrease in magnetic force.
また、フェライト粒子中の磁壁は、結晶構造がペロブスカイト構造であるＴｉ成分原料を添加すること及び高温・高酸化雰囲気下で焼成を行うことにより効果的に形成させることができ、磁壁面積の制御は前記Ｔｉ成分原料の添加量及び焼成工程における焼成温度と酸素濃度などによって行うことができることを突き止め本発明に成すに至った。 In addition, the domain wall in the ferrite particles can be effectively formed by adding a Ti component raw material having a perovskite crystal structure and firing in a high-temperature, high-oxidation atmosphere. The inventors of the present invention have found out that the present invention can be carried out depending on the amount of the Ti component material added, the sintering temperature and the oxygen concentration in the sintering step, and the present invention has been accomplished.
すなわち、本発明の大きな特徴の一つは、キャリア芯材を構成するフェライト粒子がＴｉを含有することにある。前述のように、ペロブスカイト構造のＴｉ成分原料を添加することによって、その機構は未だ明確ではないがフェライト粒子中に磁壁が形成されやすくなる。 That is, one of the major features of the present invention is that the ferrite particles constituting the carrier core material contain Ti. As described above, the addition of a Ti component raw material having a perovskite structure facilitates formation of a magnetic domain wall in ferrite particles, although the mechanism is not yet clear.
本発明で使用できるペロブスカイト構造のＴｉ成分原料としては、ＣａＴｉＯ３、ＳｒＴｉＯ３、ＢａＴｉＯ３、ＭｇＴｉＯ３などのチタン酸アルカリ土類金属が挙げられる。また、これらのＴｉ成分原料の添加量は、キャリア芯材におけるＴｉ含有量が０．６質量％以上１．２質量％以下となる範囲とするのが望ましい。キャリア芯材のＴｉ含有量が０．６質量％未満であると、磁壁面積が小さくキャリア芯材の高抵抗化が図れないおそれがある。一方、キャリア芯材のＴｉ含有量が１．２質量％を超えると、磁壁面積が広くなる反面、磁壁内のフェライト成分の総量が少なくなり、トナーへの電荷供給量が低下するおそれがある。 Examples of the Ti component raw material having a perovskite structure that can be used in the present invention include alkaline earth metal titanates such as CaTiO 3 , SrTiO 3 , BaTiO 3 , and MgTiO 3 . It is desirable that the amount of the Ti component material added be in a range where the Ti content in the carrier core material is 0.6% by mass or more and 1.2% by mass or less. If the Ti content of the carrier core material is less than 0.6% by mass, the domain wall area may be small and the carrier core material may not have high resistance. On the other hand, when the Ti content of the carrier core material exceeds 1.2% by mass, the domain wall area is increased, but the total amount of ferrite components in the domain wall is reduced, and the charge supply amount to the toner may be reduced.
また本発明では、フェライト粒子内の磁壁面積量の指標として、残留磁化σｒ（Ａｍ２／ｋｇ）に対する保持力Ｈｃ（１０３／４π・Ａ／ｍ）の比率Ｈｃ／σｒを用いることとし、比率Ｈｃ／σｒを１１．０以上１３．０以下としたことが本発明のもう一つの大きな特徴である。比率Ｈｃ／σｒが１１．０未満であると、フェライト粒子中の磁壁面積が十分でなく、キャリア芯材の高抵抗化が図れずトナーに対する帯電付与性を高められない。一方、比率Ｈｃ／σｒが１３．０を超えると磁壁が多くなりすぎ、磁壁内のフェライト成分が少なくなるためトナーへの電荷供給量が低下し、トナー帯電性が低下する。 In the present invention, the ratio Hc / σr of the coercive force Hc (10 3 / 4πA / m) to the residual magnetization σr (Am 2 / kg) is used as an index of the domain wall area in the ferrite particles. Another major feature of the present invention is that Hc / σr is 11.0 or more and 13.0 or less. If the ratio Hc / σr is less than 11.0, the domain wall area in the ferrite particles is not sufficient, the resistance of the carrier core material cannot be increased, and the charge imparting property to the toner cannot be enhanced. On the other hand, if the ratio Hc / σr exceeds 13.0, the number of magnetic domain walls becomes too large, and the amount of ferrite in the magnetic domain walls becomes small, so that the amount of charge supplied to the toner decreases, and the toner chargeability decreases.
残留磁化σｒは０．４〜０．６（Ａｍ２／ｋｇ）の範囲が好ましい。また保持力Ｈｃは５．０〜７．０（１０３／４π・Ａ／ｍ）の範囲が好ましい。 The residual magnetization σr is preferably in the range of 0.4 to 0.6 (Am 2 / kg). Further, the holding force Hc is preferably in the range of 5.0 to 7.0 (10 3 / 4πA / m).
本発明におけるフェライト粒子の組成に特に限定はなく、例えば、一般式ＭＸＦｅ３−ＸＯ４（但し、ＭはＭｇ，Ｍｎ，Ｃｕ，Ｚｎ，Ｎｉなどの金属，０＜Ｘ＜１）で表される組成の粒子が挙げられる。また、Ｃａ、Ｓｒ、Ｂａの少なくとも１種の元素を含有しているのが好ましい。これらの組成の中でもＴｉを含有するＭｎフェライト粒子、Ｔｉを含有するＭｇフェライト粒子及びＴｉを含有するＭｎＭｇフェライト粒子が好適に使用される。 There is no particular limitation on the composition of the ferrite particles in the present invention, for example, the general formula M X Fe 3-X O 4 ( where, M is Mg, Mn, Cu, Zn, a metal such as Ni, 0 <X <1) with Particles of the composition represented are mentioned. Further, it preferably contains at least one element of Ca, Sr, and Ba. Among these compositions, Mn ferrite particles containing Ti, Mg ferrite particles containing Ti, and MnMg ferrite particles containing Ti are preferably used.
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２０μｍ〜５０μｍの範囲が好ましく、粒度分布はシャープであるのが好ましい。 Although the particle size of the carrier core material of the present invention is not particularly limited, the volume average particle size is preferably in the range of 20 μm to 50 μm, and the particle size distribution is preferably sharp.
次に、本発明のキャリア芯材を構成するフェライト粒子の製造方法について説明する。フェライト粒子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。 Next, a method for producing ferrite particles constituting the carrier core material of the present invention will be described. The method for producing ferrite particles is not particularly limited, but the production method described below is preferred.
まず、Ｆｅ成分原料、Ｍ成分原料、Ｔｉ成分原料を秤量し、原料混合粉を作製する。なお、ＭはＭｇ，Ｍｎ，Ｃｕ，Ｚｎ，Ｎｉ等の２価の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。また、必要によりＣａ成分原料、Ｓｒ成分原料、Ｂａ成分原料を添加する。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であればＣａＯ、Ｃａ（ＯＨ）２、ＣａＣＯ３等が好適に使用される。また、ＳｒであればＳｒＣＯ３、Ｓｒ（ＮＯ３）２などが好適に使用される。また前述のように、Ｔｉ成分原料としては、結晶構造がペロブスカイト構造のものが使用され、ＣａＴｉＯ３、ＳｒＴｉＯ３、ＢａＴｉＯ３、ＭｇＴｉＯ３などのチタン酸アルカリ土類金属が好適に使用される。 First, an Fe component raw material, an M component raw material, and a Ti component raw material are weighed to prepare a raw material mixed powder. Note that M is at least one metal element selected from divalent metal elements such as Mg, Mn, Cu, Zn, and Ni. If necessary, a Ca component raw material, a Sr component raw material, and a Ba component raw material are added. As the Fe component raw material, Fe 2 O 3 or the like is preferably used. As the M component raw material, Mn may be MnCO 3 , Mn 3 O 4 or the like, and if it is Mg, MgO, Mg (OH) 2 or MgCO 3 may be suitably used. For Ca, CaO, Ca (OH) 2 , CaCO 3 and the like are preferably used. In the case of Sr, SrCO 3 , Sr (NO 3 ) 2 and the like are preferably used. As described above, as the Ti component raw material, one having a perovskite crystal structure is used, and alkaline earth metal titanate such as CaTiO 3 , SrTiO 3 , BaTiO 3 , and MgTiO 3 is 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 calcined. The temperature of the pre-baking is preferably in the range of 750 ° C to 900 ° C. When the temperature is 750 ° C. or higher, ferrite formation is partially promoted by calcination, the amount of gas generated during calcination is small, and the reaction between solids is sufficiently advanced. On the other hand, a temperature of 900 ° C. or less is preferable because sintering by calcination is weak and the raw material can be sufficiently pulverized in a subsequent slurry pulverization step. The atmosphere during the preliminary firing is preferably an air atmosphere.
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、結合粒子が少なく、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 disintegrated and charged into a dispersion medium to produce a slurry. In addition, the raw material mixed powder may be charged into the dispersion medium without calcination to prepare a slurry. Water is suitable as the dispersion medium used in the present invention. A binder, a dispersant, and the like may be added to the dispersion medium, if necessary, in addition to the calcined raw material. As the binder, for example, polyvinyl alcohol can be suitably used. It is preferable that the amount of the binder is about 0.5% by mass to 2% by mass in the slurry. As the dispersant, for example, ammonium polycarboxylate and the like can be suitably used. It is preferable that the amount of the dispersing agent is adjusted so that the concentration in the slurry is about 0.5% by mass to 2% by mass. In addition, a lubricant, a sintering accelerator and the like may be blended. The solid concentration of the slurry is desirably in the range of 50% by mass to 90% by mass. More preferably, it is 60% by mass to 80% by mass. When the content is 60% by mass or more, pores in the particles are small in the granulated product, and insufficient sintering during firing can be prevented. On the other hand, when the content is 80% by mass or less, the amount of the binder particles is small, and the deterioration of the fluidity due to the 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 prepared as described above is wet-pulverized. For example, wet pulverization is performed for a predetermined time using a ball mill or a vibration mill. The volume average particle size of the pulverized raw material is preferably 10 μm or less, more preferably 5 μm or less. It is preferable that a medium having a predetermined particle diameter is included in a vibration mill or a ball mill. Examples of the material of the media include iron-based chromium steel, oxide-based zirconia, titania, and alumina. The form of the pulverizing step may be any of a continuous type and a batch type. The particle size of the pulverized material is adjusted according to the pulverizing time, the rotation speed, the material and the particle size of the medium 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 granulated by spray drying. Specifically, the slurry is introduced into a spray drier such as a spray drier, and is sprayed into the atmosphere to granulate into a sphere. The ambient temperature during spray drying is preferably in the range of 100C to 300C. Thereby, a spherical granulated product having a particle size of 10 μm to 200 μm is obtained. In addition, it is desirable that the obtained granules have 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。焼成温度としては通常よりも高い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る。また、磁壁の出現が促進しないおそれがある。一方、焼成温度が１３００℃を超えると、過剰焼結による過大グレインが発生するおそれがある。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 fired to generate ferrite particles. The firing temperature is preferably in the range of 1100 ° C. to 1300 ° C., which is higher than usual. If the firing temperature is lower than 1100 ° C., phase transformation hardly occurs and sintering hardly proceeds. Further, the appearance of domain walls 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 heating rate up to the firing temperature is preferably in the range of 200 ° C./h to 500 ° C./h.
加えて、焼成工程における酸素濃度を通常よりも高くする。焼成工程における酸素濃度を高くすることによって、磁壁の出現が促進されて粒子の高抵抗化が図られる。具体的には、酸素濃度を６％〜１５％の範囲とするのが好ましい。これにより、前記のペロブスカイト構造のＴｉ成分原料の配合と相まって、粒子中の磁壁の出現が促進される。 In addition, the oxygen concentration in the firing step is set higher than usual. By increasing the oxygen concentration in the firing step, the appearance of domain walls is promoted, and the resistance of the particles is increased. Specifically, the oxygen concentration is preferably in the range of 6% to 15%. Thereby, the appearance of the magnetic domain wall in the particles is promoted in combination with the mixing of the Ti component raw material having the perovskite structure.
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〜５０μｍの範囲が好ましい。 The ferrite particles thus obtained are pulverized if necessary. Specifically, for example, the fired product is pulverized by a hammer mill or the like. The form of the pulverizing step may be any of a continuous type and a batch type. Then, if necessary, classification may be performed to adjust the particle diameter to a predetermined range. As the classification method, a conventionally known method such as air classification or sieve classification can be used. After the primary classification by an air classifier, the particle size may be adjusted to a predetermined range by a vibration sieve or an ultrasonic sieve. Further, after the classification step, the nonmagnetic particles may be removed by a magnetic field separator. The volume average particle diameter of the ferrite particles is preferably in the range of 20 μm to 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さらなる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 classified ferrite particles may be heated in an oxidizing atmosphere to form an oxide film on the surface of the particles to further increase the resistance of the ferrite particles (high resistance treatment). The oxidizing atmosphere may be an air atmosphere or a mixed atmosphere of oxygen and nitrogen. Further, the heating temperature is preferably in the range of 200 ° C to 800 ° C, 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 a desired charging property or the like, the outer periphery of the carrier core material is coated with a resin to obtain a carrier for electrophotographic development.
キャリア芯材の表面を被覆する樹脂としては、従来公知のものが使用でき、例えば、ポリエチレン、ポリプロピレン、ポリ塩化ビニル、ポリ−４−メチルペンテン−１、ポリ塩化ビニリデン、ＡＢＳ（アクリロニトリル−ブタジエン−スチレン）樹脂、ポリスチレン、（メタ）アクリル系樹脂、ポリビニルアルコール系樹脂、並びにポリ塩化ビニル系やポリウレタン系、ポリエステル系、ポリアミド系、ポリブタジエン系等の熱可塑性エストラマー、フッ素シリコーン系樹脂などが挙げられる。 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) A) resins, polystyrene, (meth) acrylic resins, polyvinyl alcohol resins, thermoplastic elastomers such as polyvinyl chloride, polyurethane, polyester, polyamide, and polybutadiene, and fluorosilicone resins.
キャリア芯材の表面を樹脂で被覆するには、樹脂の溶液又は分散液をキャリア芯材に施せばよい。塗布溶液用の溶媒としては、トルエン、キシレン等の芳香族炭化水素系溶媒；アセトン、メチルエチルケトン、メチルイソブチルケトン、シクロヘキサノン等のケトン系溶媒；テトラヒドロフラン、ジオキサン等の環状エーテル類溶媒；エタノール、プロパノール、ブタノール等のアルコール系溶媒；エチルセロソルブ、ブチルセロソルブ等のセロソルブ系溶媒；酢酸エチル、酢酸ブチル等のエステル系溶媒；ジメチルホルムアミド、ジメチルアセトアミド等のアミド系溶媒などの１種又は２種以上を用いることができる。塗布溶液中の樹脂成分濃度は、一般に０．００１質量％〜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 a resin, a solution or dispersion of the resin may be applied to the carrier core material. Examples of the solvent 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, butyl cellosolve and the like; ester solvents such as ethyl acetate and butyl acetate; and one or more kinds of amide solvents such as dimethylformamide and dimethylacetamide. . The resin component concentration in the coating solution is generally in the range of 0.001% by mass to 30% by mass, and particularly preferably in the range of 0.001% by mass to 2% by mass.
キャリア芯材への樹脂の被覆方法としては、例えばスプレードライ法や流動床法あるいは流動床を用いたスプレードライ法、浸漬法等を用いることができる。これらの中でも、少ない樹脂量で効率的に塗布できる点で流動床法が特に好ましい。樹脂被覆量は、例えば流動床法の場合には吹き付ける樹脂溶液量や吹き付け時間によって調整することができる。 As a method for coating the carrier core material with a resin, for example, a spray drying method, a fluidized bed method, a spray drying method using a fluidized bed, an immersion method, and the like can be used. Among them, the fluidized bed method is particularly preferred in that the coating can be performed efficiently with a small amount of resin. The resin coating amount can be adjusted by, for example, the amount of the resin solution to be sprayed or the spraying time in the case of the fluidized bed method.
キャリアの体積平均粒子径は１０μｍ〜２００μｍの範囲、特に２０μｍ〜５０μｍの範囲が好ましい。 The volume average particle size of the carrier is preferably in the range of 10 μm to 200 μm, particularly preferably in the range of 20 μm to 50 μm.
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 and the toner prepared as described above. The mixing ratio of the carrier and the toner is not particularly limited, and may be appropriately determined based on the developing conditions of the developing device used. Generally, the toner concentration in the developer is preferably in the range of 1% by mass to 15% by mass. If the toner concentration is less than 1% by mass, the image density becomes too low, while if the toner concentration exceeds 15% by mass, the toner scatters in the developing device, and the toner adheres to the inside of the apparatus and the background portion such as transfer paper. This is because there is a possibility that a malfunction may occur. A more preferred 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, those produced by a conventionally known method such as a polymerization method, a pulverization classification method, a melt granulation method, and 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。 Generally, the particle size 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 size 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. One or more of these 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。 For mixing the carrier and the toner, a conventionally known mixing device can be used. For example, a Henschel mixer, a V-type mixer, a tumbler mixer, a hybridizer and 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１に、磁気ブラシ現像を行う現像装置の一例を示す概説図を示す。図１に示す現像装置は、複数の磁極を内蔵した回転自在の現像ローラ３と、現像部へ搬送される現像ローラ３上の現像剤量を規制する規制ブレード６と、水平方向に平行に配置され、互いに逆向きに現像剤を撹拌搬送する２本のスクリュー１，２と、２本のスクリュー１，２の間に形成され、両スクリューの両端部において、一方のスクリューから他方のスクリューに現像剤の移動を可能とし、両端部以外での現像剤の移動を防ぐ仕切板４とを備える。 The development method using the developer of the present invention is not particularly limited, but a magnetic brush development method is preferable. FIG. 1 is a schematic diagram illustrating an example of a developing device that performs magnetic brush development. The developing device shown in FIG. 1 has a rotatable developing roller 3 containing a plurality of magnetic poles, a regulating blade 6 for regulating the amount of developer on the developing roller 3 conveyed to the developing section, and is arranged in parallel in a horizontal direction. Formed between the two screws 1 and 2 and the two screws 1 and 2 for stirring and transporting the developer in opposite directions to each other, and developing from one screw to the other screw at both ends of both screws. And a partition plate 4 which 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 helical 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 discharge the developer. Convey in opposite directions. Then, at both ends of the screws 1 and 2, the developer moves from one screw to the other screw. As a result, the developer composed of the toner and the 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 a developing magnetic pole N 1 , a conveying magnetic pole S 1 , a peeling magnetic pole N 2 , and a pumping magnetic pole N 3 as a magnetic pole generating means inside a metal cylindrical body having a surface having irregularities of several μm. , 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 transported to the developing area after its layer is regulated by the regulating blade 6.
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 area, a bias voltage in which an AC voltage is superimposed on a DC voltage is applied to the developing roller 3 from a transfer voltage power supply 8. The DC voltage component of the bias voltage is a potential between the background portion potential and the image portion potential on the surface of the photosensitive drum 5. The background portion potential and the image portion potential are potentials between the maximum value and the minimum value of the bias voltage. The peak-to-peak voltage of the bias voltage is preferably in the range of 0.5 to 5 kV, and the frequency is preferably in the range of 1 to 10 kHz. Further, the waveform of the bias voltage may be any of a rectangular wave, a sine wave, and a triangular wave. As a result, the toner and the carrier vibrate in the developing area, and the toner adheres to the electrostatic latent image on the photosensitive drum 5 to perform development.
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。また、搬送磁極Ｓ１や現像磁極Ｎ１によって現像剤は現像ローラ３にしっかりと吸着しキャリア飛散が抑制される。 Developer then on the developing roller 3 is conveyed into the apparatus by the conveyor pole S 1, and peeled from the developing roller 3 by the peeling electrode N 2, in the apparatus is recirculated conveyed by the screw 1 and 2, subjected to developing Mixed 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 scooping pole N 3, new developer is supplied from the screw 1 to the developing roller 3. This prevents image density unevenness. Further, the developer by the conveyance pole S 1 and the developing magnetic pole N 1 is firmly adsorbed to carrier scattering to the developing roller 3 can be suppressed.
なお、図１に示した実施形態では現像ローラ３に内蔵された磁極は５つであったが、現像剤の現像領域での移動量を一層大きくしたり、汲み上げ性等を一層向上させるために、磁極を８極や１０極、１２極と増やしてももちろん構わない。 In the embodiment shown in FIG. 1, the developing roller 3 has five magnetic poles. However, in order to further increase the amount of movement of the developer in the developing area and to further improve the pumping property and the like. Of course, the number of magnetic poles may be increased to eight, ten, or twelve.
参考例１
キャリア芯材を次のようにして作製した。原料としてのＦｅ２Ｏ３（平均粒径：０．３μｍ）１７．０４ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．５μｍ）６．５１ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８６ｋｇ、ＭｇＴｉＯ３（ペロブスカイト構造，平均粒径：１．５μｍ）０．３９ｋｇを純水６．２ｋｇ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０．６ｗｔ％添加して混合物とした。この混合物の固形分濃度は８０ｗｔ％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。
Reference Example 1
A carrier core material was produced as follows. 17.04 kg of Fe 2 O 3 (average particle size: 0.3 μm) as a raw material, 6.51 kg of Mn 3 O 4 (average particle size: 0.5 μm), 0.86 kg of MgO (average particle size: 0.6 μm) 0.39 kg of MgTiO 3 (perovskite structure, average particle size: 1.5 μm) was dispersed in 6.2 kg of pure water, and 0.6 wt% of an ammonium polycarboxylate-based dispersant was added as a dispersant to form a mixture. . The solid content concentration of this mixture was 80% by weight. 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 of about 130 ° C. by a spray dryer to obtain a dried granulated product having a particle size of 10 to 75 μm. Coarse particles were separated from the granulated material using a sieve mesh having a mesh of 54 μm, and fine particles were separated using a sieve mesh having a mesh of 33 μm.
この造粒物を、電気炉に投入し１２００℃まで５時間かけて昇温した。その後１２００℃で４．５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。電気炉内の酸素濃度は１０％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。 The granulated product was put into an electric furnace and heated to 1200 ° C. over 5 hours. After that, baking was performed by holding at 1200 ° C. for 4.5 hours. Then, it was cooled to 500 ° C. at a cooling rate of 2 ° C./min. A gas mixture of oxygen and nitrogen was supplied into the furnace so that the oxygen concentration in the electric furnace was 10%.
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（平均粒径）３５．５μｍ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 diameter (average particle diameter) of 35.5 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 kept at 450 ° C. for 1.5 hours in an air atmosphere to perform an oxidation treatment (resistance increasing treatment) to obtain a carrier core material.
得られたキャリア芯材の組成、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。 The composition, magnetic properties, charging properties and the like of the obtained carrier core material were measured by the methods described below. Table 2 shows the measurement results.
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, a carrier was prepared by coating the surface of the carrier core material thus obtained with a resin. Specifically, a coating solution was prepared by dissolving 450 parts by weight of a silicone resin and 9 parts by weight of (2-aminoethyl) aminopropyltrimethoxysilane in 450 parts by weight of toluene as a solvent. The coating solution was applied to 50,000 parts by weight of a carrier core material using a fluidized bed type coating apparatus, and heated in an electric furnace at a temperature of 300 ° C. to obtain a carrier. Hereinafter, a carrier was obtained in the same manner as in the comparative example.
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 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 the toner / (the weight of the toner and the carrier) = 5/100. Hereinafter, a developer was obtained in the same manner for all the comparative examples. The obtained developer was evaluated in an actual machine described later. Table 2 shows the evaluation results.
（実施例１）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１６．９２ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）６．４７ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８５ｋｇ、ＣａＴｉＯ３（ペロブスカイト構造，平均粒径：１．５μｍ）０．５５ｋｇを用いた以外は参考例１と同様にして平均粒径３５．２μｍのキャリア芯材を作成した。
( Example 1 )
16.92 kg of Fe 2 O 3 (average particle size: 0.3 μm), 6.47 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.85 kg of MgO (average particle size: 0.6 μm) as raw materials, A carrier core material having an average particle size of 35.2 μm was prepared in the same manner as in Reference Example 1 except that 0.55 kg of CaTiO 3 (perovskite structure, average particle size: 1.5 μm) was used.
（参考例２）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１６．７６ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）６．４０ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８５ｋｇ、ＳｒＴｉＯ３（ペロブスカイト構造，平均粒径：１．５μｍ）０．７９ｋｇを用いた以外は参考例１と同様にして平均粒径３５．１μｍのキャリア芯材を作成した。
( Reference Example 2 )
16.76 kg of Fe 2 O 3 (average particle size: 0.3 μm), 6.40 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.85 kg of MgO (average particle size: 0.6 μm) as raw materials, A carrier core material having an average particle size of 35.1 μm was prepared in the same manner as in Reference Example 1, except that 0.79 kg of SrTiO 3 (perovskite structure, average particle size: 1.5 μm) was used.
（実施例２）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１６．３４ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）６．２４ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８２ｋｇ、ＢａＴｉＯ３（ペロブスカイト構造，平均粒径：１．８μｍ）１．３９ｋｇを用いた以外は参考例１と同様にして平均粒径３３．４μｍのキャリア芯材を作成した。
( Example 2 )
16.34 kg of Fe 2 O 3 (average particle size: 0.3 μm), 6.24 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.82 kg of MgO (average particle size: 0.6 μm) as raw materials, A carrier core material having an average particle size of 33.4 μm was prepared in the same manner as in Reference Example 1 except that 1.39 kg of BaTiO 3 (perovskite structure, average particle size: 1.8 μm) was used.
（比較例１）
ＭｇＴｉＯ３を配合しなかった以外は参考例１と同様にして平均粒径３４．４μｍのキャリア芯材を作成した。
(Comparative Example 1)
A carrier core material having an average particle size of 34.4 μm was prepared in the same manner as in Reference Example 1 except that MgTiO 3 was not added.
（比較例２）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１５．３２ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）５．８５ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．７７ｋｇ、ＳｒＴｉＯ３（ペロブスカイト構造，平均粒径：１．５μｍ）２．８５ｋｇを用い、焼成温度を９００℃とした以外は参考例１と同様にして平均粒径３５．７μｍのキャリア芯材を作成した。
(Comparative Example 2)
15.32 kg of Fe 2 O 3 (average particle size: 0.3 μm), 5.85 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.77 kg of MgO (average particle size: 0.6 μm) as raw materials, Using 2.85 kg of SrTiO 3 (perovskite structure, average particle size: 1.5 μm), a carrier core material having an average particle size of 35.7 μm was prepared in the same manner as in Reference Example 1 except that the firing temperature was 900 ° C.
（比較例３）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１７．１４ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）６．５５ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８７ｋｇ、ＴｉＯ２（ルチル構造，平均粒径：０．４μｍ）０．２５ｋｇを用いた以外は参考例１と同様にして平均粒径３３．７μｍのキャリア芯材を作成した。
(Comparative Example 3)
17.14 kg of Fe 2 O 3 (average particle size: 0.3 μm), 6.55 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.87 kg of MgO (average particle size: 0.6 μm) as raw materials, A carrier core material having an average particle size of 33.7 μm was prepared in the same manner as in Reference Example 1, except that 0.25 kg of TiO 2 (rutile structure, average particle size: 0.4 μm) was used.
（比較例４）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１７．０８ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）６．５３ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８６ｋｇ、ＴｉＯ２（ルチル構造，平均粒径：０．４μｍ）０．３３ｋｇを用いた以外は参考例１と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 4)
17.08 kg of Fe 2 O 3 (average particle size: 0.3 μm), 6.53 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.86 kg of MgO (average particle size: 0.6 μm) as raw materials, A carrier core material having an average particle size of 34.3 μm was prepared in the same manner as in Reference Example 1 except that 0.33 kg of TiO 2 (rutile structure, average particle size: 0.4 μm) was used.
（比較例５）
原料としてＦｅ２Ｏ３（平均粒径：０．３μｍ）１６．９６ｋｇ、Ｍｎ３Ｏ４（平均粒径：０．４μｍ）６．４８ｋｇ、ＭｇＯ（平均粒径：０．６μｍ）０．８６ｋｇ、ＴｉＯ２（ルチル構造，平均粒径：０．４μｍ）０．５０ｋｇを用いた以外は参考例１と同様にして平均粒径３５．２μｍのキャリア芯材を作成した。
(Comparative Example 5)
16.96 kg of Fe 2 O 3 (average particle size: 0.3 μm), 6.48 kg of Mn 3 O 4 (average particle size: 0.4 μm), 0.86 kg of MgO (average particle size: 0.6 μm) as raw materials, A carrier core material having an average particle size of 35.2 μm was prepared in the same manner as in Reference Example 1 except that 0.50 kg of TiO 2 (rutile structure, average particle size: 0.4 μm) was used.
（比較例６）
焼成工程における焼成温度を１２００℃とし、電気炉内の酸素濃度を０．１％とした以外は比較例２と同様にして平均粒径３５．１μｍ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 35.1 μm was prepared in the same manner as in Comparative Example 2 except that the firing temperature in the firing step was 1200 ° C. and the oxygen concentration in the electric furnace was 0.1%.
（組成分析）
実施例及び比較例のキャリア芯材の組成（質量％）を下記の方法で算出した。
（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。
（Ｃａの分析）
キャリア芯材のＣａ含有量は、Ｍｇの分析同様にＩＣＰによる定量分析で行った。
（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。
（Ｂａの分析）
キャリア芯材のＢａ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)
The compositions (% by mass) of the carrier core materials of Examples and Comparative Examples were calculated by the following methods.
(Analysis of Fe)
A carrier core material containing an iron element was weighed and dissolved in a mixed acid aqueous solution of hydrochloric acid and nitric acid. After evaporating the solution to dryness, sulfuric acid aqueous solution 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 this solution was quantitatively analyzed by potentiometric titration with a potassium permanganate solution to determine the titer of Fe (Fe 2+ ).
(Analysis of Mn)
The Mn content of the carrier core material was quantitatively analyzed in accordance with 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 Mn content 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 Mg content obtained by the quantitative analysis by this ICP.
(Analysis of Ca)
The Ca content of the carrier core material was determined by quantitative analysis by ICP as in the analysis of Mg.
(Sr analysis)
The Sr content of the carrier core material was determined by ICP quantitative analysis in the same manner as Mg analysis.
(Analysis of Ba)
The Ba content of the carrier core material was determined by quantitative analysis using ICP as in the analysis of Mg.
(Analysis of Ti)
The Ti content of the carrier core was determined by quantitative analysis by ICP as in the analysis of Mg.
（磁力の測定）
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、残留磁化σｒ、保磁力Ｈｃ及び７９．５８×１０３Ａ／ｍ（１０００エルステッド）の磁場における磁化σ１ｋ（Ａｍ２／ｋｇ）をそれぞれ測定した。
(Measurement of magnetic force)
Using a vibrating sample magnetometer (VSM) ("VSM-P7" manufactured by Toei Industry Co., Ltd.) exclusively for room temperature, an external magnetic field is continuously applied for one cycle in a range of 0 to 79.58 × 10 4 A / m (10000 Oersted). And the magnetization σ 1k (Am 2 / kg) in a magnetic field of 79.58 × 10 3 A / m (1000 Oe) was measured, respectively.
（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 placed in a 100 ml glass bottle with a stopper, and left to stand at 25 ° C. and 50% relative humidity for 12 hours to adjust humidity. The conditioned carrier core material and toner are shaken with a shaker for 15 minutes to mix. The shaking was performed at 126 times / min at an angle of 60 ° using a NEW-YS model manufactured by Yayoi Co., Ltd. 300 mg of the electrophotographic developer after 15 minutes of stirring was collected, EA02 manufactured by U-Tech and an automatic suction device were used, the suction pressure was High, the separation mesh was 795 mesh made of SUS, and the toner collecting device was a filter capsule (U-Tech) EA010C), the charge amount after suction for 90 seconds was measured. The same sample was measured twice, and the average value was defined as the charge amount of the carrier core material. The charge amount of the carrier core material was calculated from the following equation. 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 suction of filter capsule (g) −weight before suction of filter capsule (g))
（実機評価）
図１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、画像形成（印字率５％）を１０００枚行った後、キャリア飛散及びカブリを下記の手順及び基準で評価した。
(Actual machine evaluation)
The developing device having the structure shown in FIG. 1 (the peripheral speed of the developing roller Vs: 406 mm / sec, the peripheral speed of the photosensitive drum Vp: 205 mm / sec, the distance between the photosensitive drum and the developing roller: 0.3 mm) was manufactured. After the two-component developer was charged and image formation (printing rate 5%) was performed on 1000 sheets, carrier scattering and fog were evaluated according to the following procedures and criteria.
キャリア飛散
白紙を１０００枚印刷し、１０００枚目の用紙における黒点の数を目視で判断した。評価基準は下記の通りである。
「○」：発見された黒点の数が１〜５個の場合
「×」：発見された黒点の数が１１個以上の場合
Carrier scattering 1000 white sheets were printed, and the number of black spots on the 1000th sheet was visually determined. The evaluation criteria are as follows.
“○”: When the number of discovered black spots is 1 to 5 “×”: When the number of discovered black spots is 11 or more
カブリ
上記１，０００枚目の用紙における非画像形成部の画像濃度を１０か所測定し、この平均値から未使用の白紙について測定した濃度を差し引き、この値を用いて下記基準で評価した。なお、画像濃度は反射濃度計「ＴＣ−６Ｄ」（東京電色社製）を用いて測定した。
「○」：濃度差が０．００６未満
「×」：濃度差が０．００６以上
Fog The image density of the non-image forming portion of the 1,000th sheet was measured at 10 points, the density measured for unused white paper was subtracted from the average value, and this value was used to evaluate the following criteria. The image density was measured using a reflection densitometer “TC-6D” (manufactured by Tokyo Denshoku Co., Ltd.).
"O": Density difference is less than 0.006 "X": Density difference is 0.006 or more
ペロブスカイト構造のＴｉ成分原料を用いると共に、焼成温度を１２００℃と高くし、また電気炉内の酸素濃度を１０％と高くした実施例１，２及び参考例１，２のキャリア芯材では、磁壁面積の指標としてのＨｃ／σｒが１１．２〜１２．１と所望の磁壁面積を有していると考えられ、帯電量は３８〜４２μＣ／ｇと高く、画像のカブリは生じなかった。また、磁化σ１ｋについても５６Ａｍ２／ｋｇ以上を有しており、キャリア飛散は生じなかった。 In the carrier core materials of Examples 1 and 2 and Reference Examples 1 and 2 in which a Ti component raw material having a perovskite structure was used, the firing temperature was increased to 1200 ° C., and the oxygen concentration in the electric furnace was increased to 10%, It is considered that Hc / [sigma] r as an index of the area has a desired domain wall area of 11.2 to 12.1, the charge amount was as high as 38 to 42 [mu] C / g, and no image fogging occurred. Also, the magnetization σ 1k was 56 Am 2 / kg or more, and carrier scattering did not occur.
これに対して、Ｔｉ成分原料を配合しなかった比較例１のキャリア芯材では、Ｈｃ／σｒが１０．８と低く所望の磁壁面積を有していないと考えられ、帯電量は３５μＣ／ｇと低く画像のカブリが生じた。 On the other hand, in the carrier core material of Comparative Example 1 in which the Ti component raw material was not blended, Hc / σr was as low as 10.8 and did not have a desired domain wall area, and the charge amount was 35 μC / g. And image fog was low.
また、比較例２では、ペロブスカイト構造のＴｉ成分原料（ＳｒＴｉＯ３）を多く配合すると共に、焼成温度を９００℃と低くしたため、得られたキャリア芯材のＨｃ／σｒが１３．７と過度に高くなり、磁化σ１ｋが３７Ａｍ２／ｋｇと低くキャリア飛散が生じた。また、帯電量も２５μＣ／ｇと低く画像のカブリが生じた。 In Comparative Example 2, a large amount of a Ti component raw material (SrTiO 3 ) having a perovskite structure was added, and the firing temperature was lowered to 900 ° C., so that the obtained carrier core material had an excessively high Hc / σr of 13.7. The magnetization σ 1k was as low as 37 Am 2 / kg, and carrier scattering occurred. Further, the charge amount was as low as 25 μC / g, and image fogging occurred.
比較例３，４，５は、ルチル構造のＴｉ成分原料（ＴｉＯ２）の配合量を変えたものであって、得られたキャリア芯材はいずれもＨｃ／σｒは１０．８以下と低く、帯電量も３５μＣ／ｇ以下と低く画像のカブリが生じた。また、比較例５のキャリア芯材では、磁化σ１ｋが５４Ａｍ２／ｋｇと低くキャリア飛散も生じた。 In Comparative Examples 3, 4, and 5, the compounding amount of the rutile structure Ti component raw material (TiO 2 ) was changed, and the carrier core materials obtained all had a low Hc / σr of 10.8 or less. The charge amount was as low as 35 μC / g or less, and image fogging occurred. In the carrier core material of Comparative Example 5, the magnetization σ 1k was as low as 54 Am 2 / kg, and carrier scattering occurred.
比較例６では、ペロブスカイト構造のＴｉ成分原料（ＳｒＴｉＯ３）を多く配合すると共に、焼成工程における電気炉内の酸素濃度を０．１％と低くしたため、得られたキャリア芯材のＨｃ／σｒが９．１と過度に低くなり、帯電量は２１μＣ／ｇと低く画像のカブリが生じた。 In Comparative Example 6, a large amount of Ti component raw material (SrTiO 3 ) having a perovskite structure was added, and the oxygen concentration in the electric furnace in the firing step was reduced to 0.1%, so that Hc / σr of the obtained carrier core material was reduced. The charge amount was as low as 9.1, and the image was fogged.
本発明のキャリア芯材によれば所望の抵抗と磁力とが得られ、キャリア飛散及びカブリといった不具合が抑制され有用である。 According to the carrier core material of the present invention, desired resistance and magnetic force can be obtained, and problems such as carrier scattering and fogging are suppressed, which is useful.
３ 現像ローラ
５ 感光体ドラム
3 developing roller 5 photosensitive drum
Claims (4)
Ｔｉの含有量が０．６質量％以上１．２質量％以下の範囲であり、
前記フェライト粒子がＣａ及びＢａの少なくとも１つの元素を含有し、
残留磁化σｒ（Ａｍ２／ｋｇ）に対する保持力Ｈｃ（１０３／４π・Ａ／ｍ）の比率Ｈｃ／σｒが１１．０以上１３．０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 Ti,
The content of Ti is in the range of 0.6% by mass or more and 1.2% by mass or less;
The ferrite particles contain at least one element of Ca and Ba,
A carrier core material, wherein a ratio Hc / σr of a coercive force Hc (10 3 / 4πA / m) to a residual magnetization σr (Am 2 / kg) is 11.0 or more and 13.0 or less.
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