Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1999-02-24
2001-04-17
Copenheaver, Blaine (Department: 1771)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036100, C428S036200, C428S035200, C442S286000, C442S289000, C442S394000, C442S396000, C442S397000, C427S145000, C382S276000, C156S135000, C156S184000
Reexamination Certificate
active
06217964
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to an endless belt and method of making it for use in digital imaging systems, and more particularly, to such a seamless, reinforced belt which may be used in intermediate image transfer, toner fusing or transfusing, and/or sheet transport operations.
Digital imaging systems are widely used in the field of xerography and electrography where dry or liquid toner is used to print text and graphic images. For example, systems which use digitally addressable writing heads to form latent images include laser, light-emitting diode, and electron beam printers. Copiers use optical means to form latent images. Regardless of how they are formed, the latent images are inked (or toned), transferred and fixed to a paper or polymer substrate. Such imaging systems typically include a component such as an endless belt, roll or drum which is utilized for latent image recording, intermediate image transfer (transfer of a toner image to the belt followed by transfer to a substrate), transfusing of toner (transport of the unfused image onto the belt with subsequent fusing), contact fusing, or electrostatic and/or frictional transport of imaging substrates such as paper, transparencies, etc.
In the case of endless belts, such belts are typically moved or driven under appropriate traction and tension by rotating cylindrical rollers. As such belts play a critical role in the imaging or substrate transport process, they must be engineered to meet exacting standards. For example, image transfer belts must be seamless, flexible, and must exhibit uniform flatness. Further, the belts should provide certain electrical properties (dielectric constant, volume and surface resistivity, etc.) chemical properties (resistance to humidity, UV light, etc.) and dimensional specifications (circumference, thickness, width, etc.) which may vary depending on the desired application.
Accordingly, there is a need in the art for an endless belt for use in digital imaging systems which can be manufactured and operated to be within exacting tolerances, including surface flatness, and which may be used for a wide variety of imaging, image transfer or sheet transport operations.
SUMMARY OF THE INVENTION
The present invention meets that need by providing an endless belt having precise and uniform flatness which also possesses a working surface which can be tailored to provide the proper characteristics for image recording, image transfer or sheet transport.
In accordance with one aspect of the present invention, an endless belt for use in a digital imaging system is provided which has first and second edges and a plurality of plies. By uniform flatness, it is meant that the thickness of the belt varies less than 0.001 inches (0.003 cm) from the first edge to the second edge and also from one circumferential point (location) to another. The circumferential uniformity of the belt also varies less than 0.005 inches (0.013 cm) in conicity to provide circumferential uniformity over the entire belt structure.
In a preferred embodiment of the invention, the belt comprises an elastomeric base ply, an intermediate polymer ply on the base ply, and an outer elastomeric ply on the intermediate ply. It should be understood that for purposes of the present invention, the term “on” when referring to the position of the plies means that one ply is adjacent to and in contact with the ply that it is “on”. Further, it should be understood that for purposes of the present invention, the terms “ply” and “layer” are interchangeable.
The outer ply functions as a working surface layer which is adapted to accept an imaging composition or to transport a substrate. For example, the surface layer may be used as a latent image recording surface; as an intermediate image transfer surface which accepts a toned and unfused image from a latent image recording component; as a dielectric surface which accepts electrostatic charges for attracting, holding in register, and transporting paper or transparency substrates; or as a toner fusing surface which can press and fix (or fuse) toner to a substrate.
The outer ply preferably comprises an elastomer selected from the group consisting of silicone, fluorosilicone, fluorocarbon, EPDM (ethylene-propylene diene terpolymers), EPM (ethylene-propylene copolymers), polyurethane elastomers, and blends thereof
In one embodiment of the invention, the outer ply is electrically conductive. By electrically conductive, it is meant that the ply has a resistivity of less than about 10
14
ohm·cm. The outer ply preferably has a surface resistivity of less than about 10
14
ohm/square, which is desirable for intermediate image transfer, toner fusing or transfusing applications. In applications as latent image recording or substrate transport in which a surface charge density is applied to the outer or working surface layer, the outer elastomeric ply preferably has a volume resistivity of about 10
12
ohm·cm or greater.
In another embodiment of the invention, the outer ply is electrically insulative. By electrically insulative, it is meant that the ply has a volume resistivity of higher than about 10
14
ohm·cm. The surface resistivity of the outer ply is about 10
14
ohm/square or higher, which is desirable for electrostatic applications which involve gripless substrate transport over the belt surface.
The intermediate polymer ply preferably comprises a polymer selected from the group consisting of polytetrafluoroethylene, polyetherimide, polyvinylidene fluoride, and ethylene-chlorotrifluoroethylene. The intermediate ply is preferably etched on both surfaces so as to achieve good adhesion with the surrounding elastomeric plies.
The elastomeric base ply is preferably selected from the group consisting of silicone, fluorosilicone, fluorocarbon, EPDM (ethylene-propylene diene terpolymers), EPM (ethylene-propylene copolymers), polyurethane elastomers, and blends thereof.
In the above embodiment, for greater circumferential strength, an elastomer-impregnated spun cord layer may be included between the base ply and the intermediate ply to provide additional support to the belt. By “cord”, we mean either a single fiber or multiple fibers formed into a continuous cord. By “impregnated”, we mean that the elastomer at least partially occupies spaces between the spun fiber or fibers but does not necessarily impregnate individual fibers. The elastomer preferably comprises any of the elastomers listed above. Alternatively, the belt may include both an elastomer-impregnated spun cord layer and a woven or non-woven fabric ply on the spun cord layer. The fabric ply is also preferably impregnated with any of the above elastomers.
In an alternative embodiment of the invention, the belt comprises an outer polymer layer and an elastomeric base ply. In this embodiment, the outer polymer layer is preferably selected from the group consisting of polytetrafluoroethylene, polyetherimide, polyvinylidene fluoride, and ethylene-chlorotrifluoroethylene. The outer layer is preferably etched on the surface contacting base ply to achieve good adhesion with the base ply. The base ply is preferably selected from the group consisting of silicone, fluorosilicone, fluorocarbon, EPDM, and blends thereof
In this embodiment, the belt may optionally include an elastomer-impregnated spun cord layer on the base layer and/or a woven or non-woven fabric ply on the spun cord layer as described above.
The present invention also provides a method of making the endless belt for use in a digital imaging system. In one embodiment, the method generally comprises the steps of applying an uncured elastomer to a workpiece such as a mandrel to form a base layer, applying an intermediate polymer layer over the base layer, applying an outer layer of an uncured elastomer over the intermediate polymer layer, and then curing the assembled layers.
The method preferably includes the step of etching both sides of the intermediate polymer layer prior to its application over the base layer.
The method may include the step of applying an
Haddock William Haul
Ndebi Sylvain L.
Shannon Allen T.
Copenheaver Blaine
Day International Inc.
Kilworth, Gottman, Hagan & Schaeff, L.L.P.
Singh Arti R.
LandOfFree
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