JP4206681B2 - Color image forming apparatus - Google Patents

Description

【００８０】
表１において、一層目（中間転写体側）のトナー（中間転写体対向トナー）はイエロー（Ｙ）のトナー１３_Yであり、また二層目のトナーはマゼンタ（Ｍ）のトナー１３_Mであり、更に三層目のトナーはシアン（Ｃ）のトナー１３_Cであり、更に四層目（紙側）のトナーはブラック（ＢＫ）のトナー１３_BKである。なお、一ないし四層は、図３（ｂ）および（ｃ）において上から順に位置する色のトナーの層を表している。
【００８１】
表１に示すように、実施例▲１▼では、一層目のイエロートナー１３_Yの外添剤遊離率が０.２６％、二層目のマゼンタトナー１３_Mの外添剤遊離率が０.１５％、三層目のシアントナー１３_Cの外添剤遊離率が０.１５％、四層目のブラックトナー１３_BKの外添剤遊離率が０.１８％である。また、実施例▲２▼では、一層目のイエロートナー１３_Yの外添剤遊離率が０.２６％、二層目のマゼンタトナー１３_Mの外添剤遊離率が０.２１％、三層目のシアントナー１３_Cの外添剤遊離率が０.１５％、四層目のブラックトナー１３_BKの外添剤遊離率が０.１８％である。
【００８２】
一方、比較例▲１▼では、一層目のイエロートナー１３_Yの外添剤遊離率が０.１５％、二層目のマゼンタトナー１３_Mの外添剤遊離率が０.２１％、三層目のシアントナー１３_Cの外添剤遊離率が０.１５％、四層目のブラックトナー１３_BKの外添剤遊離率が０.１８％である。また、比較例▲２▼では、一層目のイエロートナー１３_Yの外添剤遊離率が０.１５％、二層目のマゼンタトナー１３_Mの外添剤遊離率が０.１５％、三層目のシアントナー１３_Cの外添剤遊離率が０.２１％、四層目のブラックトナー１３_BKの外添剤遊離率が０.１８％である。
【００８３】
各色の外添剤遊離率は、それぞれ、各現像器１１_Y,１１_M,１１_C,１１_BKにそれぞれ供給される各トナー１３_Y,１３_M,１３_C,１３_BKに関し、外添剤１５_Y,１５_M,１５_C,１５_BKの母粒子１４_Y,１４_M,１４_C,１４_BKへの最大付着量を測定するとともに、遊離外添剤１５_Y′,１５_M′,１５_C′,１５_BK′の最大外添剤遊離量を測定し、外添剤１５_Y,１５_M,１５_C,１５_BKの全量（最大付着量＋最大外添剤遊離量）に対する遊離外添剤１５_Y′,１５_M′,１５_C′,１５_BK′の百分率を計算することで求めた。
【００８４】
更に、表１に示すように、実験の結果、二次転写効率は実施例▲１▼が９８.１％、実施例▲２▼が９２.３％であり、これに対して比較例▲１▼が８１.７％、比較例▲２▼が７５.８％であった。
この実験結果から明らかなように、本発明に属する実施例▲１▼および▲２▼では二次転写効率が比較的高く、また本発明に属さない比較例▲１▼および▲２▼では二次転写効率が比較的低いので、本発明により二次転写がより良好に行うことができることがわかった。
【００８５】
次に、本発明に属する前述の実施例▲１▼と本発明に属さない前述の比較例▲１▼とについてトナーの帯電特性について試験を行った。その場合、トナー帯電特性の試験はトナーの帯電量を測定することで行った。トナー帯電量の測定は、トナーサンプル濃度が３ｗｔ％になるようにトナーサンプルとキャリア（ＦＬ１８４−１５０／パウダーテック製）を混合し、回転数１００ｒｐｍで１５分間撹拌しトナーを帯電させる。そして、小型帯電量測定器（Ｍｏｄｅｌ ２１０ＨＳ−２／トレック製）を用いて、トナー帯電量を測定した。
実施例▲１▼および比較例▲１▼における各色のトナーの同期直線（同期分布グラフ）の傾きの得られた結果および帯電量の測定結果を表２に示す。
【００８６】
【表２】

【００８７】
表２に示すように、実施例▲１▼では、イエロー（Ｙ）のトナー１３_Yの同期直線（同期分布グラフ）の傾きが０.５２０、マゼンタ（Ｍ）のトナー１３_Mの同期直線（同期分布グラフ）の傾きが０.５１５、シアン（Ｃ）のトナー１３_Cの同期直線（同期分布グラフ）の傾きが０.５１３、ブラック（ＢＫ）のトナー１３_BKの同期直線（同期分布グラフ）の傾きが０.５２２であり、４色の傾きはほぼ同一である。また、比較例▲１▼では、イエロー（Ｙ）のトナー１３_Yの同期直線（同期分布グラフ）の傾きが０.６８５、マゼンタ（Ｍ）のトナー１３_Mの同期直線（同期分布グラフ）の傾きが０.４８９、シアン（Ｃ）のトナー１３_Cの同期直線（同期分布グラフ）の傾きが０.６６２、ブラック（ＢＫ）のトナー１３_BKの同期直線（同期分布グラフ）の傾きが０.７１２であり、４色の傾きにはかなりのばらつきがある。
【００８８】
帯電量の測定の結果、実施例▲１▼では、イエロー（Ｙ）のトナー１３_Yの帯電量が−１７.８μＣ／ｇ、マゼンタ（Ｍ）のトナー１３_Mの帯電量が−１８.３μＣ／ｇ、シアン（Ｃ）のトナー１３_Cの帯電量が−１８.２μＣ／ｇ、ブラック（ＢＫ）のトナー１３_BKの帯電量がー１８.６μＣ／ｇであり、４色の帯電量はほぼ同一であった。また、比較例▲１▼では、イエロー（Ｙ）のトナー１３_Yの帯電量が−２１.３μＣ／ｇ、マゼンタ（Ｍ）のトナー１３_Mの帯電量が／１５.４μＣ／ｇ、シアン（Ｃ）のトナー１３_Cの帯電量が−２０.０μＣ／ｇ、ブラック（ＢＫ）のトナー１３_BKの帯電量が−２５.８μＣ／ｇであり、４色の帯電量にはかなりのばらつきがあった。
この測定結果から明らかなように、本発明に属する実施例▲１▼では帯電特性がほぼ均一となり、また本発明に属さない比較例▲１▼では帯電特性が各色毎に異なることがわかった。
【００８９】
なお、前述の各例のカラー画像形成装置１では、いずれも、イエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、およびブラック（ＢＫ）の４色のトナーを用いたフルカラーの画像を形成するものとしているが、本発明は、二次転写を行う２色以上の複数色のトナーを用いたカラー画像を形成するものであれば、どのようなカラー画像形成装置にも適用することができる。
【００９０】
【発明の効果】
以上の説明から明らかなように、本発明のカラー画像形成装置によれば、中間転写体と対向する中間転写体対向トナーの母粒子から遊離した遊離外添剤の外添剤遊離率を０.２％以上にし、かつこれより他の色のトナーの外添剤遊離率を小さく設定するか、または、中間転写体と対向する中間転写体対向トナーの母粒子から遊離した遊離外添剤の外添剤遊離率を他の色のトナーの外添剤遊離率より大きく設定しているので、中間転写体対向トナーの中間転写体との間に比較的多く存在する遊離外添剤により、中間転写体と複数色のトナーとの間の付着力を低減でき、中間転写体からの複数色のトナーの剥離性を向上させることができるようになる。したがって、これらのトナーを中間転写体からより確実に剥離させて転写材に二次転写できるので、二次転写効率を効果的に向上でき、良好なトナーの二次転写特性を得ることができる。
【００９１】
また、中間転写体対向トナー以外のトナーの間に遊離外添剤を比較的少なくできるので、密着力を大きくでき、トナーパッキング性を向上できる。これにより、トナーの静電気力を大きくでき、転写力を増大できる。
【００９２】
特に、請求項３の発明によれば、複数色のトナーの外添剤遊離率を、それぞれ、対応する現像器に供給されるトナーの外添剤遊離率で規定しているので、複数色のトナーの外添剤遊離率をより簡単に設定できるようになる。
また、請求項４の発明によれば、複数色のトナーとして、それぞれ、イエロー、マゼンタ、シアンおよびブラックのトナーを用いているので、高画質のフルカラーの画像を得ることができる。
【図面の簡単な説明】
【図１】 本発明にかかるカラー画像形成装置の実施の形態の一例であるフルカラ−の中間転写型のカラー画像形成装置を模式的に示す図である。
【図２】 トナーの母粒子に対する外添剤の付着状態を示す図である。
【図３】 図１に示すカラー画像形成装置における４色のトナー重なり状態を示し、（ａ）は４色のトナーが像担持体から中間転写体に中間転写（一次転写）された状態を示す図、（ｂ）は４色のトナーが中間転写体から転写材に二次転写された状態を示す図、（ｃ）は加熱定着時の転写材上の４色のトナーの状態を示す図である。
【図４】 パーティクルアナライザで分析したトナーの母粒子に対する外添剤の付着状態を示し、（ａ）は母粒子に外添剤が付着した同期直線の傾きが小さい場合を示す図、（ｂ）は母粒子に外添剤が付着した同期直線の傾きが大きい場合を示す図である。
【図５】 本発明の実施の形態の他の例を模式的にかつ部分的に示す図である。
【図６】 本発明の実施の形態の更に他の例を模式的にかつ部分的に示す図である。
【図７】 本発明の実施の形態の更に他の例を模式的にかつ部分的に示す図である。
【符号の説明】
１…画像形成装置、２…露光装置、３_Y,３_M,３_C,３_BK…トナー像形成装置、４…中間転写体、５_Y,５_M,５_C,５_BK…（一次）転写装置、６…転写材、７…二次転写装置、８…定着器、８ａ…加熱ローラ（定着部材）、９_Y,９_M,９_C,９_BK…像担持体、１０_Y,１０_M,１０_C,１０_BK…帯電器、１１_Y,１１_M,１１_C,１１_BK…現像器、１２…クリーニング装置、１３,１３_Y,１３_M,１３_C,１３_BK…トナー、１４,１４_Y,１４_M,１４_C,１４_BK…母粒子、１４′…非同期母粒子、１５,１５_Y,１５_M,１５_C,１５_BK…外添剤、１５′,１５_Y′,１５_M′,１５_C′,１５_BK′…遊離外添剤、１５″,１５_Y″,１５_M″,１５_C″,１５_BK″…同期外添剤[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the technical field of a color image forming apparatus that forms a color image by transferring toners of two or more colors (two or more colors) such as yellow, magenta, cyan, and black on a transfer material such as paper. In particular, a plurality of colors of toner are primarily transferred onto the intermediate transfer member for primary transfer, and the toner on the intermediate transfer member is secondarily transferred to a transfer material and fixed to the toner of the plurality of colors superimposed on the transfer material. It belongs to the technical field of color image forming apparatuses.
[0002]
[Prior art]
Conventionally, in a full-color image forming apparatus, for example, yellow, magenta, cyan, and black toners are sequentially superimposed and transferred onto a transfer material such as paper, and the superimposed toners of four colors are heated and fixed. A full color image is formed.
[0003]
Conventionally, toners used for image formation, including toners used in such full-color image forming apparatuses, are generally improved in order to improve toner properties such as fluidity or chargeability. The external additive according to the purpose is attached to the mother particles.
[0004]
In that case, in order to improve the toner characteristics more effectively, Japanese Patent Laid-Open No. 2001-66821 discloses that toner characteristics such as chargeability are improved by defining the coverage of the external additive to the mother particles. Proposed. In the external addition of the external additive to the mother particles disclosed in this publication, the coverage ratio of the external additive to the mother particles is determined based on the average particle diameters of the mother particles and the external additive, the mother particles and the external additive. From the specific gravity and the amount of the external additive added to the mother particles, etc., a predetermined formula assuming that all of the added external additives coat the mother particles is obtained.
[0005]
The process of developing the electrostatic latent image with one color toner and transferring it to the transfer material is a full color image by successively and repeatedly transferring the four color toners of cyan, yellow, magenta, and black onto the transfer material. In this method, the amount of the fluidization imparting agent, which is an external additive contained in the toner of each color, is increased as the toner of the color that contributes to the development later, so that the toner characteristics are improved and transfer defects are reduced. Japanese Patent Laid-Open No. 6-324525 proposes to obtain a clear full color image.
[0006]
[Problems to be solved by the invention]
By the way, in the image forming apparatus, the toner image in which the electrostatic latent image is developed is transferred to a transfer material such as paper and then fixed to form an image on the transfer material. In such a case, in a color image forming apparatus which starts transfer of a plurality of color toners onto a transfer material and then fixes them, such as a full color image forming apparatus, the toners of a plurality of colors are primarily transferred onto an intermediate transfer member and this intermediate transfer There is a color image forming apparatus in which toner on a body is secondarily transferred to a transfer material and fixed to a plurality of color toners stacked on the transfer material.
[0007]
In such a color image forming apparatus, when the toner on the intermediate transfer member is secondarily transferred to the transfer material, a part of the toner remains on the intermediate transfer member, and good secondary transfer may not be performed. is there.
[0008]
Therefore, as disclosed in the above-mentioned publications, it is conceivable to improve the secondary transfer efficiency by improving the toner characteristics and improving the secondary transfer characteristics of the toner.
[0009]
First, considering the improvement of the secondary transfer characteristics of the toner by improving the toner characteristics disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 2001-66821, the improvement of the toner characteristics disclosed in this publication is added as a premise. All external additives cover the mother particles. However, in practice, the added external additive does not adhere to the mother particles, and free external additives released from the mother particles are often mixed in the toner. Therefore, it cannot be said that the external additive coverage disclosed in this publication appropriately represents the adhesion state of the external additive to the mother particles. Therefore, even if the improvement in toner characteristics disclosed in this publication is simply applied to a color image forming apparatus that secondary-transfers a plurality of colors of toner to a transfer material via an intermediate transfer member, the secondary transfer efficiency is effective. It is difficult to improve.
[0010]
Further, considering the improvement of the secondary transfer characteristics of the toner by the improvement of the toner characteristics disclosed in the above-mentioned JP-A-6-324525, the improvement of the toner characteristics disclosed in this publication discloses that the toner of each color is contained in the toner. The amount of the external additive contained is simply increased as the color toner contributes to development later. However, as described above, since there are many cases where free external additives are actually mixed in the toner as described above, the toner of the color that contributes to the development later is disclosed in this publication. If the addition amount is simply increased, the adhesion state of the external additive to the mother particles cannot be said to be appropriate. Therefore, even if the improvement in toner characteristics disclosed in this publication is simply applied to a color image forming apparatus that secondary-transfers a plurality of colors of toner to a transfer material via an intermediate transfer member, the secondary transfer efficiency is effective. It is difficult to improve.
[0011]
Further, in a color image forming apparatus in which a plurality of color toners are secondarily transferred to a transfer material via an intermediate transfer member, the charging characteristics of the plurality of color toners are made as uniform as possible so that the developing conditions are as close as possible. However, in the improvement of the toner characteristics disclosed in the above-mentioned publications, since the adhesion state of the external additive to the mother particles is not properly taken into consideration, the charging characteristics of the toners of a plurality of colors are respectively determined. There is also a problem that it is difficult to make them as uniform as possible.
[0012]
The present invention has been made in view of such circumstances, and an object thereof is to perform secondary transfer of toner in color image formation in which a plurality of colors of toner are secondarily transferred to a transfer material via an intermediate transfer member. It is an object of the present invention to provide a color image forming apparatus capable of effectively improving efficiency and obtaining good secondary transfer characteristics.
[0013]
Another object of the present invention is to provide a color image forming apparatus in which the developing conditions can be made as uniform as possible by making the charging characteristics of a plurality of color toners more effective and uniform.
[0014]
[Means for Solving the Problems]
In order to solve this problem, the color image forming apparatus according to the first aspect of the present invention is a multi-color toner comprising a large number of base particles and a large number of external additive particles respectively attached to the base particles. In a color image forming apparatus that forms a color image by superimposing the toner image on the intermediate transfer member and performing secondary transfer of the toner on the intermediate transfer member to the transfer material and fixing the toner on the transfer material. Out of the plurality of color toners attached to the intermediate transfer member, the intermediate transfer member is an external additive for the toner facing the intermediate transfer member that is located closest to the intermediate transfer member and faces the intermediate transfer member. The external additive release rate of the free external additive released from the mother particles of the opposing toner is 0.2% or more, and the external additive release rate of the other color toners is set smaller than this. It is said.
[0015]
In the invention of claim 2, a plurality of color toners each composed of a large number of mother particles and a large number of external additive particles adhering to the mother particles are primarily transferred onto the intermediate transfer member. In a color image forming apparatus that forms a color image by secondarily transferring the toner on the intermediate transfer member to a transfer material and fixing the toner on the transfer material, the plurality of colors attached to the intermediate transfer member Among the toners, an external additive for the toner facing the intermediate transfer member, which is located closest to the intermediate transfer member and facing the intermediate transfer member, and is a free external additive released from the mother particles of the toner facing the intermediate transfer member The external additive release rate of the additive is set to be larger than the external additive release rate of the other color toners.
[0016]
Further, the invention of claim 3 is characterized in that the external additive release rates of the toners of the plurality of colors are the external additive release rates of the toners supplied to the corresponding developing devices, respectively.
[0017]
  Further, the invention of claim 4 is characterized in that the toners of the plurality of colors are toners of yellow, magenta, cyan and black, respectively, and the toner facing the intermediate transfer member is any of these toners.The
[0018]
[Action]
In the color image forming apparatus of the present invention configured as described above, the external additive release rate of the free external additive released from the mother particles of the intermediate transfer member facing toner facing the intermediate transfer member is 0.2% or more. The external additive release rate of the other color toner is set to be small, or the external additive of the free external additive released from the mother particles of the toner facing the intermediate transfer member facing the intermediate transfer member The release rate is set to be larger than the release rate of the external additives of the other color toners.
[0019]
As a result, a relatively large amount of free external additive exists between the intermediate transfer member and the intermediate transfer member. This free external additive reduces the possibility that the mother particles of the toner facing the intermediate transfer member come into contact with the intermediate transfer member, and reduces the mirror image force acting on the toner, so that the intermediate transfer member and the toner of multiple colors are not affected. The electric adhesion force of the toner is reduced, and the releasability of the toners of a plurality of colors from the intermediate transfer member is improved. Therefore, these toners are secondarily transferred to the transfer material without peeling off from the intermediate transfer member more reliably and causing a transfer residue. As a result, the secondary transfer efficiency is effectively improved, and good secondary transfer characteristics of the toner can be obtained.
[0020]
Further, since the toner other than the intermediate transfer member facing toner has a relatively small amount of free external additive between them, the adhesion is relatively large, and the toner packing property is improved. This increases the electrostatic force of the toner and increases the transfer force.
[0021]
In particular, in the third aspect of the invention, the external additive release rates of the toners of a plurality of colors are respectively defined by the external additive release rates of the toners supplied to the corresponding developing devices. This makes it possible to more easily set the external additive release rate of the toners of a plurality of colors.
In the invention of claim 4, yellow, magenta, cyan and black toners are used as the toners of a plurality of colors, respectively, and the secondary transfer efficiency of these four color toners is improved. A full color image is obtained.
[0023]
In addition, since the amount of the synchronous external additive for each color is set to be the same or substantially the same for each color, the reverse transfer toner from the intermediate transfer body to the image carrier is reduced, so that the image bearing of other colors is carried out. It is possible to prevent toners of different colors from being reversely transferred to the body. In addition, by applying a constant transfer bias at the time of secondary transfer, it becomes easier for toner to move from the intermediate transfer member to the transfer material, the secondary transfer efficiency is improved, and the transfer property in the secondary transfer is improved. .
[0025]
As shown in FIG. 1, the color image forming apparatus 1 of this example is an image forming apparatus having a tandem toner image forming method, and includes an exposure device 2 that forms an electrostatic latent image, yellow (Y), and magenta (M ), Cyan (C), and black (BK) toner image forming apparatus 3 for each color_Y, 3_M, 3_C, 3_BKFor example, as shown in the drawing, an intermediate transfer member (primary transfer member) 4 composed of a transfer belt or a transfer drum, and a primary transfer device 5 for primary transfer to the intermediate transfer member 4 respectively._Y, 5_M, 5_C, 5_BKA secondary transfer device 7 for secondary transfer of the primary transfer image on the intermediate transfer body 4 to a transfer material 6 such as paper with a transfer roller, and fixing for fixing the secondary transfer image on the transfer material 6 with a heating roller 8a. And at least a container 8.
Toner image forming apparatus 3 for each color_Y, 3_M, 3_C, 3_BKAre arranged in tandem in this order from the upstream side in the moving direction of the intermediate transfer body 4.
[0026]
Toner image forming apparatus 3 for each color_Y, 3_M, 3_C, 3_BKAre respectively image bearing members 9 on which electrostatic latent images of respective colors are formed by exposure from the exposure apparatus 2._Y, 9_M, 9_C, 9_BKAnd these image carriers 9_Y, 9_M, 9_C, 9_BKAre charged by a charging roller or the like._Y, 10_M, 10_C, 10_BKAnd an image carrier 9 by toner conveyed by a developing roller or the like._Y, 9_M, 9_C, 9_BKA developing device 11 that develops the electrostatic latent image and forms a toner image_Y, 11_M, 11_C, 11_BKAnd each image carrier 9 after the primary transfer._Y, 9_M, 9_C, 9_BKCleaning device 12 for removing toner remaining on the toner_Y, 12_M, 12_C, 12_BKAnd.
[0027]
As shown in FIG. 2, the toner 13 used in the color image forming apparatus 1 of this example is composed of a large number of toner base particles 14 and a large number of external additive 15 particles for each color. In that case, the toner 13 includes a synchronous toner having an external additive 15 attached to the toner base particle 14, an asynchronous toner base particle 14 ′ to which the external additive 15 is not attached, and an asynchronous external additive not attached to the toner base particle 14. (Free external additive) Particles 15 'are mixed. The external additive 15 attached to the toner base particles 14 is indicated by reference numeral “15 ″” in FIG.
[0028]
In the color image forming apparatus 1 of this example configured as described above, first, the toner image forming apparatus 3 for each color._Y, 3_M, 3_C, 3_BKIn FIG._Y, 9_M, 9_C, 9_BKAre the chargers 10 respectively._Y, 10_M, 10_C, 10_BKThen, each image carrier 9 is charged by the exposure device 2._Y, 9_M, 9_C, 9_BKAre exposed for each color, and each image carrier 9 is exposed._Y, 9_M, 9_C, 9_BKAn electrostatic latent image of a corresponding color is formed.
[0029]
Next, each image carrier 9_Y, 9_M, 9_C, 9_BKThe electrostatic latent images above are respectively developed by the developing units 11._Y, 11_M, 11_C, 11_BKEach image carrier 9 is developed with toner of each color conveyed by the developing roller._Y, 9_M, 9_C, 9_BKA toner image of each color is formed on the top. These toner images are respectively transferred to the primary transfer device 5._Y, 5_M, 5_C, 5_BKAs a result, the image is primarily transferred to the intermediate transfer body 4 to form a primary transfer image. In this case, first, a yellow (Y) toner image is primarily transferred onto the intermediate transfer body 4, and then a magenta (M) toner image, a cyan (C) toner image, and a black (BK) toner image are sequentially superimposed. The primary transfer is done. Therefore, after the primary transfer of the last black (BK) toner image, the yellow (Y) toner 13 is formed on the intermediate transfer member 4 as shown in FIG._YDirectly contacts the intermediate transfer member 4, and the magenta (M) toner 13 is formed on the intermediate transfer member 4._M, Cyan (C) toner 13_CAnd black (BK) toner 13_BKAre stacked in order.
[0030]
Then, the primary transfer image on the intermediate transfer body 4 on which the four color toners are superposed in this manner is secondarily transferred to a transfer material 6 such as paper by the secondary transfer device 7 to form a secondary transfer image. . In this case, the secondary transfer image formed on the transfer material 6 is a black (BK) toner 13 as shown in FIG._BKDirectly contacts the transfer material 6, and cyan (C) toner 13 is formed thereon._C, Magenta (M) toner 13_M, And yellow (Y) toner 13_YAre stacked in order.
[0031]
Further, the secondary transfer image of the transfer material 6 on which the toners of four colors are overlaid in this way is heated and fixed by the heating roller 8 a of the fixing device 8. At this time, yellow (Y) toner 13 as shown in FIG._YIs an intermediate transfer member facing toner that faces the fixing surface of the heating roller 8a.
By this heat fixing, a full-color image is formed on the transfer material 6.
[0032]
Incidentally, each toner image forming apparatus 3 in the color image forming apparatus 1 of this example._Y, 3_M, 3_C, 3_BKEach toner 13 used for_Y, 13_M, 13_C, 13_BKEach of the toners is formed from a toner having a number average molecular weight (Mn) of 2000 to 5000 and a weight average molecular weight (Mw) of 6000 to 20000 having a single molecular weight distribution curve.
[0033]
In addition, each toner image forming apparatus 3_Y, 3_M, 3_C, 3_BKEach developing device 11_Y, 11_M, 11_C, 11_BKToner 13 supplied to each inside_Y, 13_M, 13_C, 13_BKThe toner 13 for each color_Y, 13_M, 13_C, 13_BKIn a state where the toner is superimposed and primarily transferred to the intermediate transfer body 4, yellow (Y) toner 13 which is a toner facing the intermediate transfer body_YFree external additive 15_YToner 13 having a different external additive release rate of color '_M, 13_C, 13_BKFree external additive 15_M', 15_C', 15_BKIt is set to be larger than the external additive liberation rate of ′ and maximize. This yellow (Y) toner is positioned closest to the fixing surface of the heating roller 8a in a state where it is secondarily transferred to the transfer material 2.
[0034]
Toner 13 for each color_Y, 13_M, 13_C, 13_BKIt is most appropriate to determine the external additive liberation rate for the toner that has been primarily transferred to the intermediate transfer member 4 during the primary transfer._Y, 13_M, 13_C, 13_BKSince it is relatively difficult to obtain the external additive liberation rate, each developing device 11_Y, 11_M, 11_C, 11_BKToner 13 supplied to_Y, 13_M, 13_C, 13_BKBy obtaining the external additive liberation rate, the external additive liberation rate can be determined more easily.
[0035]
Further, four-color toner 13 used in the color image forming apparatus 1 of this example._Y, 13_M, 13_C, 13_BKAre the same amount of mother particles 14 between these colors._Y, 14_M, 14_C, 14_BKSynchronous external additive 15_Y″, 15_M″, 15_C″, 15_BKThe amount of ″ is the same or substantially the same, that is, the slope of a synchronization straight line (synchronization distribution graph) to be described later is set to be the same or substantially the same._YThe external toner processing time is shorter than other color toners, so that the yellow toner 13_YThe external additive release rate of the other color toner 13_M, 13_C, 13_BKIt is set to the maximum compared to the external additive release rate.
[0036]
The amount of the free external additive 15 ′, the external additive release rate, the amount of the synchronous external additive 15 ″, and the slope of the synchronization line (synchronization distribution graph) of the toner 13 of each color are, for example, each of the particle analyzer (PT1000). The adhesion state between the toner base particles 14 and the external additive 15 is analyzed by a toner analysis method using a toner, and this can be obtained simply and more accurately.
[0037]
The toner analysis method using this particle analyzer is disclosed in detail in Japanese Patent Application Laid-Open No. 2000-047425, and can be understood by referring to this publication. Therefore, a detailed description thereof is omitted here, but for the sake of simplicity. explain.
[0038]
The equivalent particle size of the toner base particles 14 and the external additive 15 obtained by this toner analysis method is shown on the graph in which the horizontal axis represents the equivalent particle diameter of the toner base particles 14 and the vertical axis represents the external additive 15. Is plotted for each particle of the toner 13, an equivalent particle size distribution diagram of the toner particles is obtained. From this equivalent particle size distribution diagram, the adhesion state of the external additive 15 to the toner base particles 14 of the toner 13 is analyzed. In this case, in this equivalent particle size distribution diagram, one approximate straight line passing through the origin obtained by using the least square method is obtained (for details, see the above-mentioned publication), and the toner base particles 14 and the external additive 15 is analyzed by the slope of this approximate straight line (that is, the synchronous distribution graph) (equivalent particle diameter of external additive 15 / equivalent particle diameter of toner base particles 14).
[0039]
By the way, in the synchronous toner in which the external additive 15 is attached to the toner base particles 14, as shown in FIG. 4A, several external additives 15 are hardened and sparse over the entire surface of the toner base particles 14. In some cases, the external additive 15 adheres almost uniformly to the toner base particles 14 over the entire surface as shown in FIG. Now, regarding these synchronous toners, if the toner base particles 14 and the external additive 15 have the same amount, the external additive 15 shown in FIG. The slope of the synchronization line (slope of the above-mentioned approximate line) is relatively small, and the slope of the synchronization line in the synchronous toner in which the external additive 15 shown in FIG. Become bigger. Therefore, the state of the synchronous toner can be known from the inclination of this straight line. Furthermore, toners having the same slope of the synchronization line have uniform charging characteristics and the same development conditions.
[0040]
The toner base particles 14 of the toner 13 used in the color image forming apparatus 1 of this example are toner base particles obtained by a pulverization method and a polymerization method (hereinafter, the former is also referred to as a pulverization method toner and the latter is also referred to as a polymerization method toner). Either is acceptable. As a pulverized toner, at least a pigment (colorant) is contained in a resin binder, and in some cases, a release agent and a charge control agent are added, and after uniform mixing with a Henschel mixer or the like as described later, biaxial extrusion After being melted and kneaded by a machine, cooled and then subjected to a coarse pulverization-fine pulverization step, an external additive is further externally added to the toner base particles obtained by the classification treatment to form toner particles.
[0041]
As the binder resin, a known toner resin can be used, for example, polystyrene, poly-α-methylstyrene, chloropolystyrene, styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer. Polymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-maleic acid copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-acrylic acid ester- Styrene or a styrene-substituted product is obtained with a styrene resin such as a methacrylic acid ester copolymer, a styrene-α-chloroacrylic acid methyl copolymer, a styrene-acrylonitrile-acrylic acid ester copolymer, or a styrene-vinyl methyl ether copolymer. Containing homopolymer or copolymer, poly Ester resin, epoxy resin, urethane modified epoxy resin, silicone modified epoxy resin, vinyl chloride resin, rosin modified maleic acid resin, phenyl resin, polyethylene, polypropylene, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate Polymers, xylene resins, polyvinyl butyral resins, terpene resins, phenol resins, aliphatic or alicyclic hydrocarbon resins, and the like can be used alone or in combination. Particularly in the present invention, a styrene-acrylic acid ester resin, a styrene-methacrylic acid ester resin, and a polyester resin are preferable. In the present invention, the binder resin preferably has a glass transition temperature of 50 ° C to 75 ° C and a flow softening temperature of 100 ° C to 150 ° C.
[0042]
As the colorant, a known toner colorant can be used. For example, carbon black, lamp black, magnetite, titanium black, chrome yellow, ultramarine blue, aniline blue, phthalocyanine blue, phthalocyanine green, Hansa Yellow G, rhodamine 6G, calco oil blue, quinacridone, benzidine yellow, rose bengal, malachite green lake, Quinoline Yellow, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 184, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 180, C.I. I. Solvent Yellow 162, C.I. I. Pigment blue 5: 1, C.I. I. Dye and pigment such as CI Pigment Blue 15: 3 can be used alone or in combination.
[0043]
As the release agent, a known toner release agent can be used. Examples thereof include paraffin wax, microwax, microcrystalline wax, cadilla wax, carnauba wax, rice wax, montan wax, polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax and the like. Among these, it is preferable to use polyethylene wax, polypropylene wax, carnauba wax, ester wax and the like.
[0044]
As the charge adjusting agent, a known toner charge adjusting agent can be used. For example, oil black, oil black BY, Bontron S-22 {manufactured by Orient Chemical Co., Ltd.}, Bontron S-34 {manufactured by Orient Chemical Co., Ltd.}, salicylic acid metal complex E-81 {Orient Chemical Co., Ltd.) Manufactured}, thioindigo pigment, sulfonylamine derivative of copper phthalocyanine, Spiron black TRH {manufactured by Hodogaya Chemical Co., Ltd.}, calixarene compound, organic boron compound, fluorine-containing quaternary ammonium salt compound, monoazo metal complex, Aromatic hydroxyl carboxylic acid metal complexes, aromatic dicarboxylic acid metal complexes, polysaccharides and the like can be mentioned. Of these, colorless or white toners are preferred for color toners.
[0045]
The component ratio (weight ratio) in the pulverized toner is 0.5 to 15 parts by weight, preferably 1 to 10 parts by weight, based on 100 parts by weight of the binder resin. The mold is 1 to 10 parts by weight, preferably 2.5 to 8 parts by weight, and the charge control agent is 0.1 to 7 parts by weight, preferably 0.5 to 5 parts by weight. Parts by weight. The pulverized toner thus obtained has an average particle diameter of 5 μm to 10 μm, preferably 6 μm to 9 μm.
[0046]
The pulverized toner of the present invention may be spheroidized for the purpose of improving transfer efficiency. For this purpose, a device that can be pulverized into a relatively round sphere in the pulverization process, for example, a machine. If a turbo mill known as a pulverizer {manufactured by Kawasaki Heavy Industries, Ltd.} is used, the circularity can be up to 0.93. Alternatively, if the pulverized toner is used with a commercially available hot-air spheronizer surfing system SFS-3 type (manufactured by Nippon Pneumatic Industry Co., Ltd.), the circularity can be up to 1.00.
[0047]
Examples of the polymerization toner include suspension polymerization and emulsion polymerization. In the suspension polymerization method, a mixture containing a polymerizable monomer (monomer), a color pigment, a release agent, and a dye, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives as necessary. The dissolved or dispersed monomer composition is added to an aqueous phase containing a suspension stabilizer (water-soluble polymer, poorly water-soluble inorganic substance) with stirring, granulated, and polymerized to obtain desired particles. Colored polymer toner particles having a size can be formed.
[0048]
Furthermore, in the emulsion polymerization method, if necessary, a polymerization initiator, an emulsifier (surfactant) and the like are further dispersed in water to carry out the polymerization, if necessary, and then a colorant and a charge control agent in the aggregation process. Colored toner particles having a desired particle size can be formed by adding a flocculant (electrolyte) and the like.
In the materials used for the production of the polymerization toner, the same materials as those of the above pulverized toner can be used for the colorant, release agent, charge control agent, and fluidity improver.
[0049]
As the polymerizable monomer (monomer), known vinyl monomers can be used. For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene. , P-ethylstyrene, vinyltoluene, 2,4-dimethylstyrene, pn-butylstyrene, p-phenylstyrene, p-chlorostyrene, divinylbenzene, methyl acrylate, ethyl acrylate, propyl acrylate, acrylic acid n-butyl, isobutyl acrylate, n-octyl acrylate, dodecyl acrylate, hydroxyethyl acrylate, 2-ethylhexyl acrylate, phenyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, methyl methacrylate, ethyl methacrylate , Methacrylate Pill, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, hydroxyethyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, acrylic acid, methacrylic acid, maleic acid, Fumaric acid, cinnamic acid, ethylene glycol, propylene glycol, maleic anhydride, phthalic anhydride, ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propyleneate, Examples include acrylonitrile, methacrylonitrile, vinyl methyl ether, vinyl ethyl ether, vinyl ketone, vinyl hexyl ketone, and vinyl naphthalene. Examples of the fluorine-containing monomer include 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, vinylidene fluoride, ethylene trifluoride, ethylene tetrafluoride, trifluoropropylene, and the like. Can be used because fluorine atoms are effective for negative charge control.
[0050]
Known emulsifiers (surfactants) can be used. For example, sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, potassium stearate, calcium oleate, dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride Hexadecyltrimethylammonium bromide, dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, and the like.
[0051]
A well-known thing can be used as a polymerization initiator. For example, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, 4,4′-azobiscyanovaleric acid, t-butyl hydroperoxide, benzoyl peroxide, 2,2′-azobis-isobutyronitrile, etc. is there.
[0052]
As the flocculant (electrolyte), known ones can be used. Examples thereof include sodium chloride, potassium chloride, lithium chloride, magnesium chloride, calcium chloride, sodium sulfate, potassium sulfate, lithium sulfate, magnesium sulfate, calcium sulfate, zinc sulfate, aluminum sulfate, and iron sulfate.
[0053]
Even in the case of the polymerization method toner of the present invention, the spheroidization treatment may be performed for the purpose of improving the transfer efficiency. As a method for adjusting the circularity of the polymerization method toner, the emulsion polymerization method is agglomeration of secondary particles. By controlling the temperature and time in the process, the circularity can be freely changed, and the range is 0.94 to 1.00. In the suspension polymerization method, since a true spherical toner is possible, the circularity is in the range of 0.98 to 1.00. Further, the degree of circularity can be freely adjusted from 0.94 to 0.98 by performing heat deformation at a temperature equal to or higher than the Tg temperature of the toner in order to adjust the degree of circularity.
[0054]
The polymerization toner can be prepared by a dispersion polymerization method other than the above-described method, for example, a method disclosed in JP-A-63-304002. In this case, since the shape is close to a true sphere, in order to control the shape, for example, pressurization can be performed at a temperature equal to or higher than the Tg temperature of the toner to obtain a desired toner shape. Thus, the obtained polymerization toner has an average particle size of 4 μm to 9 μm, preferably 4.5 μm to 8 μm.
In the present invention, the average particle diameter and the circularity of toner particles and the like are values measured with an FPIA 2100 manufactured by Sysmex Corporation.
[0055]
Examples of the external additive 15 of the toner 13 include silica, titanium dioxide, alumina, magnesium fluoride, silicon carbide, boron carbide, titanium carbide, zirconium carbide, boron nitride, titanium nitride, zirconium nitride, magnetite, molybdenum disulfide, Each fine particle of aluminum stearate, magnesium stearate, zinc stearate, calcium stearate, metal titanate and silicon metal salt having an average primary particle diameter of 1 to 500 nm, preferably 5 to 200 nm can be used. However, it is preferable to include an element that is hardly contained in the composition of the mother particle so that it can be detected by PT-1000.
[0056]
These toner base particles 14_Y, 14_M, 14_C, 14_BKAnd external additive 15_Y, 15_M, 15_C, 15_BKAre used to produce toner 13 of each color.
First, toner base particles 14 of each color_Y, 14_M, 14_C, 14_BKThe cyan toner base particles 14 are produced._CFor example, 100 parts by weight of a 50:50 (weight ratio) mixture of partially cross-linked product of polycondensation polyester of polycondensation polyester of aromatic dicarboxylic acid and alkylene etherified bisphenol A, 5 weight of phthalocyanine blue of cyan pigment Parts, 3 parts by weight of polypropylene having a melting point of 152 ° C. and a weight molecular weight Mw of 4000 as a release agent, and 2 parts by weight of a salicylic acid metal complex E-81 (manufactured by Orient Chemical Co., Ltd.) as a charge control agent After uniformly mixing using 20C, the mixture was kneaded with a twin screw extruder and cooled. The cooled product is pulverized with a jet mill, and classified with an airflow classifier._CCan be obtained.
[0057]
In addition, toner base particles 14 of other colors_Y, 14_M, 14_BKFor example, the cyan toner base particles 14_CIn the production method, magenta mother particles 14_MIn the case of quinacrine, yellow toner mother particles 14_YIn the case of Pigment Yellow 180, black toner base particles 14_BKIn this case, carbon toner is used and cyan toner base particles 14 are used._CAnd toner mother particles 14 of each color._Y, 14_M, 14_BKCan be obtained.
[0058]
Next, the toner base particles 14 of the respective colors obtained as described above._Y, 14_M, 14_C, 14_BKAn external additive 15 is added to each color toner 13._Y, 13_M, 13_C, 13_BKIs manufactured. In each color toner, silica fine particles (BET specific surface area of 141 m) surface-treated with hexamethyldisilazane with respect to 100 parts by weight of each toner base particle.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles 12 nm) is added to a Henschel mixer (20 liters) at a ratio of 0.5 to 2.5 parts by weight, and externally added in a processing time of 1 to 4 minutes at a rotation speed of 2850 rpm. By processing, toner of each color can be produced.
[0059]
According to the color image forming apparatus 1 of this example, yellow (Y) toner 13 that is an intermediate transfer member facing toner is used._YFree external additive 15_YThe external additive liberation rate of the toner of other colors 13_M, 13_C, 13_BKFree external additive 15_M', 15_C', 15_BKIt is set so as to be larger than the external additive release rate of ′ and maximize, so that the yellow (Y) toner 13_YThe free external additive 15 present between the intermediate transfer member 4 and the intermediate transfer member 4_Y′ Can be relatively large. This free external additive 15_Y′, The intermediate transfer body 4 and the toner 13_Y, 13_M, 13_C, 13_BKBetween these toners 13 from the intermediate transfer body 4 is reduced._Y, 13_M, 13_C, 13_BKCan be improved. Therefore, these toners 13_Y, 13_M, 13_C, 13_BKCan be more reliably peeled off from the intermediate transfer body 4 and secondarily transferred onto the transfer material 6. As a result, the toner 13_Y, 13_M, 13_C, 13_BKCan effectively improve the secondary transfer efficiency of the toner 13._Y, 13_M, 13_C, 13_BKExcellent secondary transfer characteristics can be obtained.
[0060]
Further, yellow (Y) toner 13_YOther color toners 13 other than_M, 13_C, 13_BKFree external additive 15_M', 15_C', 15_BKSince ′ is relatively small, these toners 13_M, 13_C, 13_BKThe adhesion strength of the toner can be relatively increased, and the toner packing property can be improved.
[0061]
By the way, yellow (Y) toner 13 which is an intermediate transfer member facing toner._YBy maximizing the external additive release rate of the toner 13,_YFree external additive 15_Y'Increases, but as described above, the four-color toner 13_Y, 13_M, 13_C, 13_BKThe same amount of mother particles 14 between_Y, 14_M, 14_C, 14_BKSynchronous external additive 15_Y″, 15_M″, 15_C″, 15_BKSince the amount of ″ is set to be the same or almost the same, other toners 13_M, 13_C, 13_BKSimilarly to yellow (Y) toner 13_YExternal additive 15_Y″ The mother particle 14_YThe toner 13 is coated uniformly and evenly._YExternal additive 15_YNeedless to say, it has improved toner characteristics and high image quality.
[0062]
Further, yellow, magenta, cyan, and black toners 13_Y, 13_M, 13_C, 13_BKThe external additive liberation rate of each of the corresponding developing devices 11_Y, 11_M, 11_C, 13_BKSince the external additive liberation rate of the toner supplied to the toner is regulated, each toner 13_Y, 13_M, 13_C, 13_BKThe external additive release rate can be set more easily.
[0063]
Further, toner base particles 14 of each color_Y, 14_M, 14_C, 14_BKSynchronous external additive 15 adhering to_Y″, 15_M″, 15_C″, 15_BKThe amount of ″ is set to be the same, that is, the slope of the synchronization straight line (approximate straight line) obtained by the toner analysis method using the PT analyzer disclosed in the above-mentioned publication is set to be the same. The charging characteristics of the four color toners 13 can be made uniform, and the development conditions can be made the same, and the development conditions can be made the same, so that the attitude of each color developer to the image carrier and the shape of each developer can be changed. Both can be made the same and the development bias can be made the same, so that various development methods can be flexibly and effectively employed according to the purpose as described above.
[0064]
Moreover, a synchronous external additive 15 for each color_Y″, 15_M″, 15_C″, 15_BKThe amount of ″ is set to be the same or substantially the same for each color, whereby each image carrier 9 from the intermediate transfer member 4 is set._Y, 9_M, 9_C, 9_BKSince the reverse transfer toner can be reduced, the image carrier 9 of another color_Y, 9_M, 9_C, 9_BKIt is possible to prevent toners of different colors from being reversely transferred. In addition, by applying a constant transfer bias at the time of secondary transfer to facilitate the movement of the toner from the intermediate transfer body 4 to the transfer material 6, the secondary transfer efficiency can be improved and good transfer in the secondary transfer can be achieved. Sex can be obtained.
[0065]
The toner image forming apparatus 3 for each color of yellow (Y), magenta (M), cyan (C), and black (BK)._Y, 3_M, 3_CThe arrangement order can be set to any order. In that case, the amount of the color toner 13 of the toner image forming apparatus located at the most upstream in the moving direction of the intermediate transfer body 4, that is, the amount of the free external additive 15 ′ of the color toner 13 that is first transferred to the intermediate transfer body 4. Is larger than the amount of the free external additive 15 ′ of the other color toner 13 (that is, the free rate of the external additive of the color toner 13 that is first transferred to the intermediate transfer body 4 is changed to that of the other color toner 13. It may be set so as to be larger than the external additive release rate.
[0066]
Further, the color image forming apparatus 1 of the present invention, as shown in FIG. 5, does not provide the image carrier 9 for each color, but provides a common image carrier (photosensitive drum) 9 for each color. For each image carrier (photosensitive drum) 9, each color developer 11_Y, 11_M, 11_C, 11_BKCan also be applied to the color image forming apparatus 1 sequentially arranged from the upstream side along the rotation direction of the image carrier 9. Also in the case of the color image forming apparatus 1 of this example, it goes without saying that the secondary transfer type color image forming apparatus 1 including the intermediate transfer body 4 is employed.
[0067]
Then, each developing device 11 of yellow (Y), magenta (M), cyan (C), and black (BK)._Y, 11_M, 11_C, 11_BKHowever, as in the above example, the amount of the free external additive 15 ′ of the color toner 13 that is first transferred to the intermediate transfer body 4 is different from the other arrangement order. More than the amount of the free external additive 15 ′ of the color toner 13 (that is, the external additive release rate of the color toner 13 that is first transferred to the intermediate transfer body 4 is set to the external addition of the other color toner 13. It is set to be larger than the agent release rate.
Other configurations and other operational effects of the color image forming apparatus 1 of this example are substantially the same as those of the above-described examples.
[0068]
Further, the color image forming apparatus 1 according to the present invention has a developing device 11 for each color shown in FIG._Y, 11_M, 11_C, 11_BKIs a rotary type color image forming apparatus 1 and a developing device 11 for each color shown in FIG._Y, 11_M, 11_C, 11_BKThe present invention can also be applied to a slide-type color image forming apparatus 1 that moves linearly. In the color image forming apparatus 1 shown in FIG. 6 and FIG. 7, it goes without saying that the intermediate transfer member 4 is provided although not shown.
The effects of the color image forming apparatus 1 of these examples are substantially the same as those of the above examples.
[0069]
Next, an example of the color image forming apparatus 1 of this example will be described.
Experiments on the secondary transfer characteristics of the toner were conducted for two examples (1) and (2) belonging to the present invention and two comparative examples (1) and (2) not belonging to the present invention.
The toner 13 used in this experiment has a molecular weight distribution curve in which the toner base particles have one peak for each color, and has a number average molecular weight (Mn) of 2000 to 5000 and a weight average molecular weight (Mw) of 6000 to 20000.
[0070]
The toner of Example (1) was produced as follows. That is, the yellow toner 13 of the first layer (opposing the intermediate transfer member surface)_YIn regard to 100 parts by weight of yellow toner base particles, silica fine particles (BET specific surface area of 141 m) surface-treated with hexamethyldisilazane are used.²/ G, volume resistivity 10¹⁵Ω · cm, average particle diameter of primary particles of 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing time of 1 minute at a rotation speed of 2850 rpm. 1) Yellow toner 13_YIt was.
[0071]
Also, the second to fourth layer (paper side) magenta toner 13_M, Cyan toner 13_CAnd black toner 13_BKIn each case, silica fine particles (BET specific surface area of 141 m, surface-treated with hexamethyldisilazane) are added to 100 parts by weight of each toner base particle.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles of 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing speed of 2850 rpm for a processing time of 3 minutes. 1 ▼ Magenta toner 13_M, Cyan toner 13_CAnd black toner 13_BKIt was.
[0072]
The toner of Example (2) was produced as follows. That is, the yellow toner 13 in one layer (opposing the intermediate transfer member) and the second layer 13_YAnd magenta toner 13_M, The silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area of 141 m) per 100 parts by weight of each toner base particle.²/ G, volume resistivity 10¹⁵Ω · cm, average particle diameter of primary particles of 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing time of 1 minute at a rotation speed of 2850 rpm. 2 ▼ Yellow toner 13_YAnd magenta toner 13_MIt was.
[0073]
Further, cyan toner 13 in the third and fourth layers (on the paper side)_CAnd black toner 13_BKIn each case, silica fine particles (BET specific surface area of 141 m, surface-treated with hexamethyldisilazane) are added to 100 parts by weight of each toner base particle.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles of 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing speed of 2850 rpm for a processing time of 3 minutes. 2 ▼ cyan toner 13_CAnd black toner 13_BKIt was.
[0074]
On the other hand, the toner of Comparative Example (1) was produced as follows. That is, yellow toner 13 in one layer (facing the fixing surface), three layers, and four layers._Y, Cyan toner 13_CAnd black toner 13_BK, The silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area of 141 m) per 100 parts by weight of each toner base particle.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing speed of 2850 rpm for 3 minutes. 1) Yellow toner 13_Y, Cyan toner 13_CAnd black toner 13_BKIt was.
[0075]
Further, the second layer of magenta toner 13_MIn each case, silica fine particles (BET specific surface area of 141 m) surface-treated with hexamethyldisilazane with respect to 100 parts by weight of magenta toner base particles.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing time of 1 minute at a rotation speed of 2850 rpm. 1 ▼ Magenta toner 13_MIt was.
[0076]
Further, the toner of Comparative Example (2) was produced as follows. That is, yellow toner 13 of one layer (fixing surface facing), two layers, and four layers._Y, Magenta toner 13_MAnd black toner 13_BK, The silica fine particles surface-treated with hexamethyldisilazane (BET specific surface area of 141 m) per 100 parts by weight of each toner base particle.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing speed of 2850 rpm for 3 minutes. 2 ▼ Yellow toner 13_Y, Magenta toner 13_MAnd black toner 13_BKIt was.
[0077]
The second layer of cyan toner 13_CIn each case, silica fine particles (BET specific surface area of 141 m) surface-treated with hexamethyldisilazane were added to 100 parts by weight of cyan toner base particles.²/ G, volume resistivity 10¹⁵Ω · cm, average particle size of primary particles 12 nm) was added to a Henschel mixer (20 liters) at a rate of 1.0 part by weight, and externally added at a processing time of 1 minute at a rotation speed of 2850 rpm. 2 ▼ Magenta Toner 13_MIt was.
[0078]
The image forming apparatus used in the experiment is the tandem image forming apparatus shown in FIG. 1, and the transfer material 6 used is ordinary paper.
Table 1 shows the external additive liberation rate of each color toner and the experimental results in Example (1) and Comparative Example (1).
[0079]
[Table 1]

[0080]
In Table 1, the first-layer (intermediate transfer member side) toner (intermediate transfer member-facing toner) is yellow (Y) toner 13._YThe second layer toner is magenta (M) toner 13._MFurther, the third layer toner is cyan (C) toner 13._CFurther, the toner in the fourth layer (paper side) is black (BK) toner 13._BKIt is. The first to fourth layers represent toner layers of colors positioned in order from the top in FIGS. 3B and 3C.
[0081]
As shown in Table 1, in Example (1), the first yellow toner 13_YThe external additive liberation rate of the toner was 0.26%, and the second layer of magenta toner 13_MThe external additive release rate of the toner is 0.15%, and the cyan toner 13 in the third layer_CThe external additive liberation rate of the toner is 0.15%, the fourth layer of black toner 13_BKThe external additive liberation rate of 0.18%. In Example (2), the yellow toner 13 for the first layer 13_YThe external additive liberation rate of the toner was 0.26%, and the second layer of magenta toner 13_MThe external additive release rate of the toner is 0.21%, and the cyan toner 13 in the third layer_CThe external additive liberation rate of the toner is 0.15%, the fourth layer of black toner 13_BKThe external additive liberation rate of 0.18%.
[0082]
On the other hand, in the comparative example (1), the first yellow toner 13_YThe external additive liberation rate of the toner was 0.15%, and the second layer of magenta toner 13_MThe external additive release rate of the toner is 0.21%, and the cyan toner 13 in the third layer_CThe external additive liberation rate of the toner is 0.15%, the fourth layer of black toner 13_BKThe external additive liberation rate of 0.18%. In Comparative Example (2), the first yellow toner 13_YThe external additive liberation rate of the toner was 0.15%, and the second layer of magenta toner 13_MThe external additive release rate of the toner is 0.15%, and the cyan toner 13 in the third layer_CThe external additive liberation rate of the toner was 0.21%, and the fourth layer of black toner 13_BKThe external additive liberation rate of 0.18%.
[0083]
The external additive liberation rate of each color is determined by each developing device 11._Y, 11_M, 11_C, 11_BKEach toner 13 supplied to each_Y, 13_M, 13_C, 13_BKExternal additive 15_Y, 15_M, 15_C, 15_BKMother particles 14_Y, 14_M, 14_C, 14_BKAnd measuring the maximum adhesion amount to the free external additive 15_Y', 15_M', 15_C', 15_BK′ Was measured for the maximum free amount of external additive, and external additive 15_Y, 15_M, 15_C, 15_BKFree external additive 15 with respect to the total amount (maximum adhesion amount + maximum external additive release amount)_Y', 15_M', 15_C', 15_BKIt was obtained by calculating the percentage of ′.
[0084]
Further, as shown in Table 1, as a result of the experiment, the secondary transfer efficiency was 98.1% in Example (1) and 92.3% in Example (2), whereas this was Comparative Example (1). ▼ was 81.7%, and Comparative Example (2) was 75.8%.
As is clear from the experimental results, the secondary transfer efficiency is relatively high in Examples (1) and (2) belonging to the present invention, and the secondary transfer efficiency is not high in Comparative Examples (1) and (2) not belonging to the present invention. Since the transfer efficiency is relatively low, it was found that the secondary transfer can be performed better according to the present invention.
[0085]
Next, the toner charging characteristics of the above-described Example (1) belonging to the present invention and the above-mentioned Comparative Example (1) not belonging to the present invention were tested. In that case, the toner charge characteristic test was performed by measuring the charge amount of the toner. To measure the toner charge amount, a toner sample and a carrier (FL184-150 / Powder Tech) are mixed so that the toner sample concentration becomes 3 wt%, and the toner is charged by stirring for 15 minutes at a rotation speed of 100 rpm. The toner charge amount was measured using a small charge amount measuring device (Model 210HS-2 / manufactured by Trek).
Table 2 shows the result of obtaining the slope of the synchronization line (synchronization distribution graph) of each color toner and the measurement result of the charge amount in Example (1) and Comparative Example (1).
[0086]
[Table 2]

[0087]
As shown in Table 2, in Example (1), yellow (Y) toner 13_YThe slope of the synchronization line (synchronization distribution graph) is 0.520 and the magenta (M) toner 13_MToner 13 with the slope of the sync line (synchronization distribution graph) of 0.515 and cyan (C)_CThe slope of the synchronization line (synchronization distribution graph) is 0.513, and black (BK) toner 13_BKThe slope of the synchronization line (synchronization distribution graph) is 0.522, and the slopes of the four colors are almost the same. In Comparative Example (1), yellow (Y) toner 13_YThe slope of the synchronization line (synchronization distribution graph) is 0.685, and magenta (M) toner 13._MToner 13 with a slope of 0.489 and cyan (C)_CThe slope of the synchronization line (synchronization distribution graph) is 0.662, and the black (BK) toner 13_BKThe slope of the synchronization line (synchronization distribution graph) is 0.712, and the slopes of the four colors vary considerably.
[0088]
As a result of the measurement of the charge amount, in Example (1), yellow (Y) toner 13_YToner with a charge amount of −17.8 μC / g and magenta (M)_MToner with a charge amount of −18.3 μC / g and cyan (C)_CToner with a charge amount of −18.2 μC / g and black (BK)_BKThe charge amount was -18.6 μC / g, and the charge amounts of the four colors were almost the same. In Comparative Example (1), yellow (Y) toner 13_YToner with a charge amount of −21.3 μC / g and magenta (M) 13_MToner with a charge of 15.4 μC / g and cyan (C)_CToner with a charge amount of −20.0 μC / g and black (BK) 13_BKThe charge amount of the toner was -25.8 μC / g, and the charge amounts of the four colors varied considerably.
As is apparent from the measurement results, it was found that in Example (1) belonging to the present invention, the charging characteristics were almost uniform, and in Comparative Example (1) not belonging to the present invention, the charging characteristics were different for each color.
[0089]
In each of the color image forming apparatuses 1 of the above-described examples, each forms a full-color image using four color toners of yellow (Y), magenta (M), cyan (C), and black (BK). However, the present invention can be applied to any color image forming apparatus as long as it forms a color image using two or more colors of toner for secondary transfer. .
[0090]
【The invention's effect】
As is apparent from the above description, according to the color image forming apparatus of the present invention, the external additive release rate of the free external additive released from the mother particles of the toner facing the intermediate transfer member facing the intermediate transfer member is set to 0. The external additive liberation rate of the other color toner is set to be 2% or more, or the external additive free from the mother particles of the toner facing the intermediate transfer member facing the intermediate transfer member is removed. Since the additive release rate is set to be larger than the external additive release rate of the other color toners, the intermediate transfer member can be used for intermediate transfer due to the relatively large amount of free external additive existing between the intermediate transfer member and the intermediate transfer member. The adhesion force between the toner and the toner of a plurality of colors can be reduced, and the releasability of the toner of the plurality of colors from the intermediate transfer member can be improved. Therefore, since these toners can be more reliably peeled off from the intermediate transfer member and secondarily transferred onto the transfer material, the secondary transfer efficiency can be effectively improved and good secondary transfer characteristics of the toner can be obtained.
[0091]
Further, since the free external additive can be relatively reduced between the toners other than the toner facing the intermediate transfer member, the adhesion can be increased and the toner packing property can be improved. Thereby, the electrostatic force of the toner can be increased and the transfer force can be increased.
[0092]
  In particular, the claims3According to the invention, the external additive release rates of the toners of a plurality of colors are respectively defined by the external additive release rates of the toners supplied to the corresponding developing devices. The liberation rate can be set more easily.
  Claims4According to this invention, yellow, magenta, cyan, and black toners are used as the toners of a plurality of colors, respectively, so that a high-quality full-color image can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram schematically showing a full-color intermediate transfer type color image forming apparatus as an example of an embodiment of a color image forming apparatus according to the present invention.
FIG. 2 is a diagram illustrating a state in which an external additive is attached to toner base particles.
FIG. 3 shows a four-color toner overlapping state in the color image forming apparatus shown in FIG. 1, and (a) shows a state where four-color toners are intermediately transferred (primary transfer) from the image carrier to the intermediate transfer member. FIG. 4B is a diagram illustrating a state in which four color toners are secondarily transferred from the intermediate transfer member to the transfer material, and FIG. 4C is a diagram illustrating a state of the four color toners on the transfer material during heat fixing. is there.
FIG. 4 shows the adhesion state of an external additive to a toner base particle analyzed by a particle analyzer, (a) is a diagram showing a case where the slope of a synchronous straight line where the external additive adheres to the mother particle is small, and (b). FIG. 4 is a diagram showing a case where the slope of the synchronization straight line in which the external additive adheres to the mother particle is large.
FIG. 5 is a diagram schematically and partially showing another example of an embodiment of the present invention.
FIG. 6 is a diagram schematically and partially showing still another example of the embodiment of the present invention.
FIG. 7 is a diagram schematically and partially showing still another example of the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2 ... Exposure apparatus, 3_Y, 3_M, 3_C, 3_BK... toner image forming apparatus, 4 ... intermediate transfer member, 5_Y, 5_M, 5_C, 5_BK... (primary) transfer device, 6 ... transfer material, 7 ... secondary transfer device, 8 ... fixing device, 8a ... heating roller (fixing member), 9_Y, 9_M, 9_C, 9_BK... Image carrier, 10_Y, 10_M, 10_C, 10_BK... Charger, 11_Y, 11_M, 11_C, 11_BK... Developer 12 ... Cleaning device 13,13_Y, 13_M, 13_C, 13_BK... Toner, 14,14_Y, 14_M, 14_C, 14_BK... mother particles, 14 '... asynchronous mother particles, 15, 15_Y, 15_M, 15_C, 15_BK... External additives, 15 ', 15_Y', 15_M', 15_C', 15_BK'... Free external additive, 15 ", 15_Y″, 15_M″, 15_C″, 15_BK″… Synchronous external additive

Claims (4)

A plurality of color toners each composed of a large number of mother particles and a large number of external additive particles attached to the mother particles are superimposed on the intermediate transfer member for primary transfer, and the toner on the intermediate transfer member is transferred. In a color image forming apparatus that forms a color image by secondary transfer to a material and fixing the toner on the transfer material,
Out of the plurality of color toners attached to the intermediate transfer member, the intermediate transfer member is an external additive for the toner facing the intermediate transfer member that is located closest to the intermediate transfer member and faces the intermediate transfer member. The external additive release rate of the free external additive released from the mother particles of the opposing toner is 0.2% or more, and the external additive release rate of the other color toners is set smaller than this. A color image forming apparatus. A plurality of color toners each composed of a large number of mother particles and a large number of external additive particles attached to the mother particles are superimposed on the intermediate transfer member for primary transfer, and the toner on the intermediate transfer member is transferred. In a color image forming apparatus that forms a color image by secondary transfer to a material and fixing the toner on the transfer material,
Out of the plurality of color toners attached to the intermediate transfer member, the intermediate transfer member is an external additive for the toner facing the intermediate transfer member that is located closest to the intermediate transfer member and faces the intermediate transfer member. A color image forming apparatus, wherein an external additive release rate of a free external additive released from a mother particle of a counter toner is set to be larger than an external additive release rate of other color toners.   3. The color image forming apparatus according to claim 1, wherein the external additive liberation rates of the plurality of color toners are the external additive liberation rates of the toners supplied to the corresponding developing devices.   4. The toner according to claim 1, wherein the plurality of color toners are yellow, magenta, cyan, and black toners, respectively, and the intermediate transfer member facing toner is one of these toners. The color image forming apparatus described.

Images