Patent Application
20080026309
The charge accumulation on the anti-curl backcoating is minimized by making the backcoating material sufficiently conducting. This eliminates the need for active charge neutralizing devices that add to the overall system cost. However, conventional additives for conductivity tend to be optically absorbing. Furthermore, the loading percentage to achieve the percolation limit for conductivity is sufficiently high that the mechanical properties of the composite material are compromised.
Thus, in accordance with the present invention, an imaging belt 100 comprises a substrate layer 20, an outer image layer 30 and an inner anti-curl backing layer 10. The inner anti-curl backing layer 10, in turn, includes one or more carbon nanotubes 5 disposed therein, together with an exposed backing layer surface 11. An image forming device 200 includes the imaging belt 100. The image forming device 200 is arranged to conductively couple the backing layer surface 11 to an included ground source 9 by means of one or more included conducting backer bars 40, one or more included grounding brushes 50, or any combination of included conducting backer bars 40 and grounding brushes 50.
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In one embodiment, the image forming device 200 comprises a copying machine.
In another embodiment, the image forming device 200 comprises a printing machine.
In still another embodiment, the image forming device 200 comprises a facsimile machine.
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Thus there is presented an anti-curl backcoating layer 10 for an organic belt photoreceptor 100 that incorporates carbon nanotubes 5 as a polymeric filler in a composite material that possesses both electrical conductivity and optical transparency. The conductivity obtained with a low percentage of carbon nanotubes 5 obviates the need for active charge neutralizing devices that are used when the backcoating is an insulative material. The optical transparency enables light exposure from the backside layer 10 for electrically erasing the photoreceptor 100 during the cycling process.
As described herein, carbon nanotubes 5 are used as a filler to impart conductivity to the anti-curl backcoating layer 10. Carbon nanotubes (“CNT”) 5 represent a new molecular form of carbon in which a single layer of atoms is rolled into a seamless tube that is on the order of 1 to 10 nanometers in diameter and up to hundreds of micrometers in length. Multi-walled nanotubes (“MWNT”) were first discovered by lijima of NEC Labs in 1991. Two years later, he discovered single-walled nanotubes (“SWNT”). Since then, nanotubes have captured the attention of researchers worldwide. Nanotubes exhibit extraordinary electrical, mechanical and thermal conductivity properties. The nanotubes can be either conducting or semi-conducting, depending on the chirality (twist) of the nanotubes. They are have yield stresses much higher than that of steel, and can be kinked without permanent damage. The thermal conductivity of CNT is much higher than that of copper, and comparable to that of diamond. The nanotubes can be fabricated by a number of methods including carbon arc discharge, pulsed laser vaporization, chemical vapor deposition (“CVD”) and high pressure CO. Variants of nanotubes that contain only carbon include nanotubes with equal amounts of boron and nitrogen.
Since the aspect ratio (length to diameter ratio) of carbon nanotubes is so high, the percolation limit (approximately the inverse of the aspect ratio) for electrical conductivity is much lower than typical conductive fillers such as carbon black. The percolation limit for the addition of SWNT in epoxy is between only 0.1 to 0.2 wt %. This level of loading does not affect the other properties of the matrix material. For higher loadings, the conductivity increases by a factor of 104. Hyperion Catalysis International, Inc., 38 Smith Place, Cambridge, Mass. 02138 produces MWNT composite materials for a variety of applications that require conductive polymeric materials.
The paper “Carbon nanotube based transparent conductive coatings” by Paul J. Glatkowski of Eikos, Inc., 2 Master Drive, Franklin, Mass. 02038, the disclosure of which paper hereinabove has been incorporated by reference, verbatim, and with the same effect as though the same disclosure were fully and completely set forth herein, (see http://www.eikos.com/articles/conductive_coatings.pdf) describes a Nanoshield™ technology for carbon nanotube based transparent conductive coatings. Eikos, Inc. has demonstrated coatings with resistivity of 105 ohms/sq at an optical transmittance of 95%.
NOTE: The term “NANOSHIELD” is a trademark of the aforementioned Eikos, Inc.
See also U.S. Pat. No. 7,060,241 to the same Paul J. Glatkowski entitled “Coatings comprising carbon nanotubes and methods for forming same”, issued Jun. 13, 2006, the disclosure of which patent hereinabove has been incorporated by reference, verbatim, and with the same effect as though the same disclosure were fully and completely set forth herein.
The anti-curl backcoating composite layer 10 containing the carbon nanotubes 5 can be grounded by either a conductive grounding brush/brushes 50 in contact with the coating, or grounded elements such as the backer bars 40 that can have sufficient conductivity to continually dissipate any charge accumulation on the backcoating layer 10.
Thus, there is described the first aspect of the invention, substantially as described in claim 1 hereinbelow, namely, an imaging belt 100 comprising a substrate layer 20, an outer image layer 30 and an inner backing layer 10, the backing layer 10 including one or more carbon nanotubes 5 disposed therein.
In one embodiment of the imaging belt 100, substantially as described in claim 2 hereinbelow, the imaging belt 100 of the backing layer 10 further comprises an anti-curl backing layer.
Also, there has been described the second aspect of the invention, substantially as described in claim 3 hereinbelow, namely, an image forming device 200 including an imaging belt 100, the imaging belt 100 comprising a substrate layer 20, an outer image layer 30 and an inner backing layer 10, the backing layer 10 including one or more carbon nanotubes 5 disposed therein.
In one embodiment of the image forming device 200, substantially as described in claim 4 hereinbelow, the backing layer 10 of the imaging belt 100 further comprises an anti-curl backing layer 10.
In a further embodiment of the image forming device 200, substantially as described in claim 5 hereinbelow, the imaging belt 100 inner backing layer 10 includes a backing layer surface 11 and the image forming device 200 is arranged to couple the backing layer surface 11 to an included ground source 9 by means of one or more included conducting backer bars 40.
In another embodiment of the image forming device 200, substantially as described in claim 6 hereinbelow, the imaging belt 100 inner backing layer 10 includes a backing layer surface 11 and the image forming device 200 is arranged to couple the backing layer surface 11 to an included ground source 9 by means of one or more included conducting grounding brushes 50.
In a still further embodiment of the image forming device 200, substantially as described in claim 7 hereinbelow, the imaging belt 100 inner backing layer 10 including a backing layer surface 11, the image forming device 200 arranged to couple the backing layer surface 11 to an included ground source 9 by means of at least one included conducting backer bar 40 together with at least one included conducting grounding brush 50.
In still another embodiment of the image forming device 200, substantially as described in claim 8 hereinbelow, the image forming device 200 comprises a copying machine.
In yet a still further embodiment of the image forming device 200, substantially as described in claim 9 hereinbelow, the image forming device 200 comprises a printing machine.
In yet still another embodiment of the image forming device 200, substantially as described in claim 10 hereinbelow, the image forming device 200 comprises a facsimile machine.
The table below lists the drawing element reference numbers together with their corresponding written description:
While particular embodiments have been described hereinabove, alternatives, modifications, variations, improvements and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications, variations, improvements and substantial equivalents.
This application is related to the commonly-assigned pending application Ser. No. 11/167,158 filed on 28 Jun. 2005 by Dan A. Hays and David J. Gervasi, entitled “Fuser and fixing members and process for making the same”, attorney docket 20040942-US-NP, now pending, the disclosure of which pending application in its entirety hereby is totally incorporated herein by reference. This application also is related to the commonly-assigned pending application Ser. No. 11/238,112 filed on 29 Sep. 2005 by Samir Kumar and Dan A. Hays, entitled “Synthetic carriers”, attorney docket 20050544-US-NP, now pending, the disclosure of which pending application in its entirety hereby is totally incorporated herein by reference. The disclosure of the following U.S. patent in its entirety hereby is totally incorporated herein by reference: Paul J. Glatkowski, U.S. Pat. No. 7,060,241, “Coatings comprising carbon nanotubes and methods for forming same”, issued Jun. 13, 2006. The disclosure of the following publication in its entirety hereby is totally incorporated herein by reference: “Carbon nanotube based transparent conductive coatings”, by Paul J. Glatkowski, Eikos, Inc., 2 Master Drive, Franklin, Mass. 02038, believed to have been posted on the website http:/Hwww.eikos.com on May 16, 2003.
