Electrophotography – Image formation – Transfer
Reexamination Certificate
2001-12-19
2003-08-12
Chapman, Mark A. (Department: 1753)
Electrophotography
Image formation
Transfer
C399S333000, C430S124300, C430S126200
Reexamination Certificate
active
06606476
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to an imaging apparatus and layers for components thereof, and for use in electrostatographic, including digital, apparatuses. The layers herein are useful for many purposes including layers for transfix films or transfuse films, and the like. More specifically, the present invention relates to layers comprising a hybrid material of a fluoroelastomer and polyamino polysiloxane material. In embodiments, the layers are useful for layers of transfix or transfuse members. In embodiments, the layer is useful as an outer layer of a transfix member. In embodiments, there may be included an optional intermediate layer between the transfix substrate and outer hybrid layer. The layers of the present invention may be useful in films, belts or the like members, and may be used in xerographic machines, especially color machines.
In a typical electrostatographic reproducing apparatus such as an electrophotographic imaging system using a photoreceptor, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of a developer mixture. One type of developer used in such printing machines is a liquid developer comprising a liquid carrier having toner particles dispersed therein. Generally, the toner is made up of resin and a suitable colorant such as a dye or pigment. Conventional charge director compounds may also be present. The liquid developer material is brought into contact with the electrostatic latent image and the colored toner particles are deposited thereon in image configuration.
The developed toner image recorded on the imaging member can be transferred to an image receiving substrate such as paper via an intermediate transfer member. Alternatively, the developed image can be transferred to an intermediate transfer member from the image-receiving member via another transfer member. The toner particles may be transferred by heat and/or pressure to an intermediate transfer member, or more commonly, the toner image particles may be electrostatically transferred to the intermediate transfer member by means of an electrical potential between the imaging member and the intermediate transfer member. After the toner has been transferred to the intermediate transfer member, it can then be transferred to the image receiving substrate, for example by contacting the substrate with the toner image on the intermediate transfer member under heat and/or pressure. Alternatively, the developed image can be transferred to another intermediate transfer member such as a transfix or transfer member. A transfix or transfuse member uses heat associated with the transfer member in order to both transfer and fix or fuse the developed image to a copy substrate.
Intermediate transfer members, including transfix or transfuse members, enable high throughput at modest process speeds. In four-color photocopier systems, the transfer member also improves registration of the final color toner image. In such systems, the four component colors of cyan, yellow, magenta and black may be synchronously developed onto one or more imaging members and transferred in registration onto a transfer member at a transfer station.
In electrostatographic printing machines in which the toner image is transferred from the transfix member to the image receiving or copy substrate, it is important that the transfer of the toner particles from the transfix member to the image receiving substrate be substantially 100 percent. Less than complete transfer to the image receiving substrate results in image degradation and low resolution. Completely efficient transfer is particularly important when the imaging process involves generating full color images since undesirable color deterioration in the final colors can occur when the color images are not completely transferred from the transfer member.
Thus, it is important that the transfix member surface has excellent release characteristics with respect to the toner particles. Conventional materials known in the art for use as transfix members often possess the strength, conformability and electrical conductivity necessary for use as transfix members, but can suffer from poor toner release characteristics, especially with respect to higher gloss image receiving substrates. When heat is associated with a transfer member, such as in the case of a transfix member, the transfix member must also possess good thermal conductivity in addition to superior release characteristics. Also, there is a need for mechanical strength for wear resistance. A transfix member undergoes multiple cycling during use.
In addition, in the event that electrically conductive fillers are needed to build electrical and thermal conductivities, and/or mechanical strength, it is necessary that the fillers be compatible with the materials used in the transfix member. Similarly, if release fluids are used, the materials in the transfix member and the fillers, if used, must be compatible with the release fluid materials. Also, the fillers, if used, and the materials in the transfix members must be chemically compatible with toners or liquid developers used in the electrostatographic apparatus.
Conventionally, for transfuse or transfix applications, a conformable member is used. Silicone is a very popular outer layer for transfix and transfuse members, especially for transfuse or transfix belts or films. Silicone possesses excellent toner release characteristics. However, the major drawback to using silicone as the outer layer is the short performance life. This is especially true in liquid marking applications, wherein the carrier fluid swells the silicone layer and results in excessive belt wear. The mechanical property of the belt deteriorates significantly, resulting in short belt life. For dry powder marking, it is believed that the mechanism of toner release requires extrusion of the silicone oligomer. The extruded oligomer serves as the release agent. However, as the oligomer is extruded, the property of the belt changes and the performance life of the belt is reduced. The belt becomes less compliant and its release function deteriorates. The extrusion degrades the belt simultaneously.
One countermeasure to the above problems is to use a fluoroelastomer surface for the transfuse member. In fact, many forms of fluoroelastomers are much stronger than silicone. However, the fluoroelastomers can usually not release toner on their own. A,release agent management (RAM) system has to be introduced in order to overcome this shortfall. The potential problem with introduction of a RAM system is that oil contamination of the entire transfuse subsystem can occur.
Further, it is desirable to provide a print engine that is targeted for all of office, production, color and offset market. Such a print engine would need to be able to print on many different types of substrates, and have the capability to mark papers of different weight and different roughness, such as wallpapers, textiles, foils, and other papers. In electrostatography, extended substrate, latitude may be accomplished through the transfuse process where the toner images are transferred and fused simultaneously. Since fusing is accomplished on the transfuse member, the member should be stiff, compliant and have sufficient toner release characteristics for the outer surface as well.
Therefore, the requirements for transfuse surfaces are demanding and sometimes conflicting.
U.S. Pat. No. 4,853,737 discloses electrostatographic rollers having an outer layer comprising a cured fluoroelastomer containing pendant polydiorganosiloxane segments that are covalently bonded to the backbone of the fluoroelastomer.
U.S. Pat. No. 5,361,126 discloses an imaging apparatus including a transfer member including a heater and pressure-applying roller, wherein the transfer member includes a fabric substrate and an impurity-absorbent material as a top layer. The impurity-absorbing material
Law Kock-Yee
Schlueter Jr. Edward L.
Tarnawskyj Ihor W.
Yuan Xiaoying (Elizabeth)
Bade Annette L.
Chapman Mark A.
Xerox Corporation
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