In a typical electrostatographic reproducing apparatus, 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 thermoplastic resin particles, which are commonly referred to as toner. Generally, the electrostatic latent image is developed with a developer mixture comprised of carrier granules having toner particles adhering triboelectrically thereto, or a liquid developer material, which may include a liquid carrier having toner particles dispersed therein. The developer material is advanced into contact with the electrostatic latent image and the toner particles are deposited thereon in image configuration. Subsequently, the developed image is transferred to a substrate, like paper.
It is advantageous to transfer the developed image to an intermediate transfer web, belt or component, and subsequently transfer with high transfer efficiency the developed image from the intermediate transfer member to a permanent substrate. The toner image is subsequently usually fixed or fused upon a support, which may be the photosensitive member itself, or other support sheet such as plain paper.
In electrostatographic printing machines wherein the toner image is electrostatically transferred by a potential between the imaging member and the intermediate transfer member, the transfer of the toner particles from the imaging member to the intermediate transfer member and the retention thereon should be substantially complete so that, for example, the image ultimately transferred to the image receiving substrate will have a high resolution. It is desirable that substantially one hundred percent of the toner transfer occurs when most or all of the toner particles comprising the image are transferred and little residual toner remains on the surface from which the image was transferred.
Intermediate transfer members are desired that allow for a number of advantages, such as enabling high throughput at modest process speeds, improving registration of the final color toner image in color systems using synchronous development of one or more component colors using one or more transfer stations, and increasing the range of final substrates that can be used. However, a disadvantage of using an intermediate transfer member is that a plurality of transfer steps is required allowing for the possibility of charge exchange occurring between toner particles and the transfer member, which ultimately can lead to less than complete toner transfer. The result is low-resolution images on the image receiving substrate and image deterioration. When the image is in color, the image can additionally suffer from color shifting and color deterioration. In addition, the incorporation of charging agents in liquid developers, although providing acceptable quality images and acceptable resolution due to improved charging of the toner, can exacerbate the problem of charge exchange between the toner and the intermediate transfer member.
A disadvantage relating to the preparation of an intermediate transfer member is that there is usually deposited a separate release layer on a metal substrate, and thereafter, there is applied to the release layer the intermediate transfer member components, and where the release layer allows the resultant intermediate transfer member to be separated from the metal substrate by peeling or by the use of mechanical devices. Thereafter, the intermediate transfer member is in the form of a film, which can be selected for xerographic imaging systems, or the film can be deposited on a supporting substrate like a polymer layer. The use of a release layer adds to the cost and time of preparation, and such a layer can modify a number of the intermediate transfer member characteristics.
For low end xerographic machines and printers that produce about 30 pages or less per minute, thermoplastic intermediate transfer members are usually used because of their low cost. However, the modulus values or break strength of thermoplastic materials, such as certain polycarbonates, polyesters, and polyamides, are relatively low, such as from about 1,000 to 2,000 Mega Pascals (MPa).
High end xerographic machines and printers that generate at least 30 pages per minute, and up to about 75 pages per minute or more, usually utilize intermediate transfer members of thermoplastic polyimides, thermosetting polyimides, or polyamideimides, primarily because of their high modulus of about 3,500 Mpa or more. However, intermediate transfer members using these materials are more expensive in that both the raw material cost and the manufacturing process cost are higher than using thermoplastic polycarbonates, polyesters, and polyamides. Thus, an economical intermediate transfer member possessing high modulus and excellent release characteristics for high end machines is desired.
There is a need for intermediate transfer members that substantially avoid or minimize the disadvantages of a number of known intermediate transfer members.
Also, there is a need for intermediate transfer members with excellent break strengths as determined by their modulus measurements, that are readily releasable from substrates, and that possess improved stability with no or minimal degradation for extended time periods, and where the main polymer incorporated into the member possesses high glass transition temperatures, such as for example, from about 180° C. to about 300° C., or greater than about 200° C., such as from about 200° C. to about 400° C., from about 215° C. to about 375° C., or from about 250 to about 375° C.,
Moreover, there is a need for intermediate transfer member materials that possess rapid release characteristics from a number of substrates that are selected when such members are prepared.
Another need relates to providing seamless intermediate transfer members that have excellent conductivity or resistivity, and that possess acceptable humidity insensitivity characteristics leading to developed images with minimal resolution issues.
Further, there is a need for seamless intermediate transfer members containing components that can be economically and efficiently manufactured.
Additionally there is a need for intermediate transfer members that possesses a suitable stable functional resistivity.
These and other needs are achievable in embodiments with the intermediate transfer members and components thereof disclosed herein.
USPTO Backgrounds
USPTO Backgrounds