Coating apparatus – Immersion or work-confined pool type – Work-confined pool
Reexamination Certificate
2001-02-22
2003-05-13
Edwards, Laura (Department: 1734)
Coating apparatus
Immersion or work-confined pool type
Work-confined pool
C118S429000
Reexamination Certificate
active
06562135
ABSTRACT:
REFERENCE TO COPENDING AND ISSUED PATENTS
Attention is directed to commonly owned and assigned, copending applications U.S. Ser. No. 09/466,565 (D/99679) filed Dec. 17, 1999, now U.S. Pat. No. 5,958,998, discloses a process for immersion coating of a substrate comprising positioning a substrate having a top and bottom within a coating vessel having an inner surface to define a space between the inner surface and the substrate, filling at least a portion of the space with a coating mixture; stopping the filling slightly below the top of the substrate, initiating removal of the coating mixture at a gradually increasing rate to a predetermined maximum flow rate in a short predetermined distance, and continuing removal of the coating mixture at substantially the predetermined maximum flow rate to deposit a layer of the coating mixture on the substrate; U.S. Ser. No. 09/450,363 (D/99726), filed Nov. 29, 1999, now U.S. Pat. No. 6,461,442, which discloses a process including: providing a hollow imaging drum having a first end, a second end, an outside surface, an inside surface and coating material on both the inside surface and the outside surface at least the first end; simultaneously contacting the coating material on both the inside surface and the outside surface at the first end of the drum with resilient foam material; flowing liquid solvent for the coating material to the foam material where the foam material contacts the first end of the drum, the foam material being insoluble in the flowing solvent; producing relative movement between the foam material and the drum to simultaneously wipe both the inside surface and the outside surface of the first end of the drum with the foam material and solvent material and simultaneously remove coating material from the inside surface and the outside surface of the first end of the drum; and flowing the solvent away from the drum to carry away coating material removed from the inside surface and the outside surface of the first end of the drum; U.S. Ser. Nos. 09/416,824 (D/97389) now U.S. Pat. No. 6,218,062 and 09/416,840 (D/97389 Q) now U.S. Pat. No. 6,177,219, both filed Nov. 12, 1999, and U.S. Ser. No. 09/576147 (D/99783 Q) filed May 22, 2000, now U.S. Pat. No. 6,156,468.
The disclosures of each the above mentioned copending applications or patents are incorporated herein by reference in their entirety. The appropriate components and processes of these applications may be selected for the materials and processes of the present invention in embodiments thereof.
BACKGROUND OF THE INVENTION
The present invention is generally directed to a coating apparatus and method of coating articles, such as hollow cylindrical articles, for example, photoresponsive devices used in imaging apparatuses and the like applications. More specifically, the present invention relates to an improved coating apparatus and coating method for articles and which apparatus and method obviates or minimizes the need to conduct a so-called bottom-edge-wipe step or operation and which step is common in conventional coating apparatus and coating methods. The present invention provides coated articles with superior and unexpected coating properties, such as reduced or eliminated coating defects, such as bubbles entrapped in the resulting coated article.
In electrophotography, and particularly in xerographic copying machines, coated substrates such as photoreceptor belts or cylindrical photoreceptor drums are common. Photoreceptor embodiments include at least one coating of photoconductive material, which can be formed on the photoreceptor by known techniques such as immersion or dip coating.
The end regions of a coated photoreceptor are commonly used to either or both engage, for example, with flanges, the printer's or copier's drive mechanism and to support a developer housing. If the developer housing rides on the coated area at one end region of the drum, the coating composition can be rubbed-off and which rub-off particles can contaminate various components in the machine such as the cleaning system and any optical exposure systems employed in the machine. Also, the coating can interfere with devices or componentry that is designed to electrically ground the drum by merely riding on the outer surface at one end region of the drum. Thus, preferably both the outer and inner end regions of a photoreceptor generally must be free of the coating composition.
In dip coating, the upper end region of the photoreceptor drum might be kept free of coating composition by orienting the drum vertically and dipping the drum into a bath of coating composition to a predetermined depth which avoids coating the upper end region. However, the coating formed over the lower region end of the photoreceptor must still be removed, for example, by mechanically or manually wiping the lower end region or by applying solvents to it. This solvent removal procedure can be problematic since it may employ environmentally harmful solvents. Also, the coating removal procedure may require the use and maintenance of special equipment in the clean room which can increase activity in the clean room, thereby decreasing productivity. In addition, the coating removal procedure a clean room increases costs since the procedure must meet clean room requirements. Alternatively, the end regions of the photoreceptor drums may be masked to prevent coating of the end regions. However, the mask must be removed from the photoreceptor drum subsequent to the dip coating process which is disadvantageous since this involves an additional step. Consequently, there is a need, which the present invention addresses, for a coating method which eliminates or minimizes the above-identified problems.
Photoresponsive articles or devices are comprised generally of a transport layer and a photogenerator layer. These devices may include a wide variety of additional or supplemental layers or coating and which coatings can provide enhanced performance properties or adaptable configurational features to the resulting coated device. The photoresponsive devices of the present invention are useful, for example, as imaging members in various electrostatographic imaging systems, including those systems wherein electrostatic latent images are formed on the imaging member. Additionally, the photoresponsive devices of the present invention can be irradiated with light, for example, as generated by a known laser or other suitable light source, to accomplish, for example, latent image formation by, for example, charged area discharge (CAD) or dark area discharge (DAD) methodologies.
Numerous photoresponsive devices for electrostatographic imaging systems are known including selenium, selenium alloys, such as arsenic selenium alloys; layered inorganic photoresponsive, and layered organic photoresponsive devices. Examples of layered organic photoresponsive devices include those containing a charge transport layer and a charge generator layer, or alternatively a photogenerator layer. Thus, for example, an illustrative layered organic photoresponsive device can be comprised of a conductive substrate, overcoated with a charge generator layer, which in turn is overcoated with a charge transport layer, and an optional overcoat layer overcoated on the charge transport layer. In a further “inverted” variation of this device, the charge transporter layer can be overcoated with the photogenerator layer or charge generator layer. Examples of generator layers that can be employed in these devices include, for example, charge generator materials such as pigments, selenium, cadmium sulfide, vanadyl phthalocyanine, x-metal free phthalocyanines, dispersed in binder resin, while examples of transport layers include dispersions of various diamines, reference for example, U.S. Pat. No. 4,265,990, the disclosure of which is incorporated herein by reference in its entirety.
There continues to be a need for improved photoresponsive devices, and improved methods and apparatus for making such devices. Additionally, there continues to be a need for methods and
Bush Steven D.
Lee James R.
Marcello Raphael A.
Swain Eugene A.
Vangrol Richard A.
Edwards Laura
Thompson Robert
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