Stress release method

#Electrostatographic flexible imaging members are well known in the electrostatographic art. Typical flexible electrostatographic imaging members include, for example, (1) photosensitive members (photoreceptors) commonly utilized in electrophotographic (xerographic) processes and (2) electroreceptors such as ionographic imaging members for electrographic imaging systems. The flexible electrostatographic imaging members may be seamless or seamed belts. Typical electrophotographic imaging member belts comprise a charge transport layer and a charge generating layer on one side of a supporting substrate layer and an anticurl backing layer coated on the opposite side of the substrate layer. A typical electrographic imaging member belt does however have a more simple material structure; it comprises a dielectric imaging layer on one side of a supporting substrate and an anticurl backing layer on the opposite side of the substrate.

#In a machine service environment, a flexible imaging member belt mounted on a belt supporting module is generally exposed to repetitive electrophotographic image cycling which subjects the outer-most charge transport layer to mechanical fatigue as the imaging member belt bends and flexes over the belt drive roller and all other belt module support rollers, as well as sliding bending contact above each backer bar's curving surface. This repetitive imaging member belt cycling leads to a gradual deterioration in the physical/mechanical integrity of the exposed outer charge transport layer leading to premature onset of charge transport layer fatigue cracking. The cracks developed in the charge transport layer as a result of dynamic belt fatiguing are found to manifest themselves into copy printout defects which thereby adversely affect the image quality on the receiving paper. In essence, the appearance of charge transport cracking cuts short the imaging member belt's intended functional life.

#When a production web stock consisting of several thousand feet of coated multi-layered photoreceptor is obtained after finishing the charge transport layer coating/drying process, it is seen to spontaneously curl upwardly and required an anticurl backing layer applied to the backside of the substrate support, opposite to the side having the charge transport layer, to offset the curl and render flat the photoreceptor web stock. The exhibition of upward photoreceptor curling after completion of charge transport layer coating has been determined to be the consequence of thermal contraction mismatch between the applied charge transport layer and the substrate support under the conditions of elevated temperature heating/drying the wet coating and eventual cooling down to room ambient temperature. Since the charge transport layer in a typical photoreceptor device has a coefficient of thermal contraction approximately 3½ times larger than the substrate support, it does, upon cooling down to room ambient temperature, result in greater dimensional contraction than that of the substrate support causing upward photoreceptor curling which thereby requires the anticurl backing layer to balance the curl and provide flatness.

#Other aspects of the present invention will become apparent as the following description proceeds and upon reference to the Figures which represent exemplary embodiments:

#FIG. 1 is a schematic elevational view of a first embodiment of apparatus useful in accomplishing the present method;

#FIG. 2 is a schematic elevational view of a second embodiment of apparatus useful in accomplishing the present method;

#Unless otherwise noted, the same reference numeral in different Figures refers to the same or similar feature.

#FIG. 1 is an exemplary embodiment of apparatus useful for carrying out the present method for treating a flexible multi-layer member exhibiting a glass transition temperature (“Tg”) and including a surface layer. The term “multi-layer” refers to two, three, four or more layers. The surface layer may or may not exhibit the Tg that is the subject of the present method; in embodiments, another layer of the member (such as a layer adjacent to the surface layer or a non-adjacent internal layer spaced a number of layers away from the surface layer) exhibits the Tg that is the subject of the present method while the surface layer exhibits a different Tg. As is well known, Tg is the temperature at which molecules in a rigid glass like state with restricted motion ability is transformed into a flexible state such that free molecular rotation/translation motions become predominant. The present method involves moving the member 10 through a member path 30 comprising: a contact zone 40 defined by contact of the member with an arcuate surface 210 including a curved contact zone region 40A; a pre-contact member path 30A before the contact zone 40; and a post-contact member path 30B after the contact zone.

#The member 10 moves toward a free rotating component 206 (depicted in embodiments as a tube) having an arcuate outer surface 210, and a chamber 209. The member 10, which initially may be at ambient temperature of about 25° C., makes an entering contact at for example about 12 O'clock and conforms to the arcuate surface 210 of component 206. In FIG. 1, the arcuate surface is driven by the moving member 10 which causes the arcuate surface to rotate; in an alternate embodiment, the arcuate surface is non-rotatable.