Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Radiation-sensitive composition or product
Reexamination Certificate
2002-10-08
2004-09-07
Dote, Janis L. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Radiation-sensitive composition or product
C430S120400, C399S159000
Reexamination Certificate
active
06787277
ABSTRACT:
BACKGROUND
The present invention is generally directed to layered imaging members, imaging apparatus, and processes thereof. More specifically, the present invention relates in general to electrophotographic imaging members and more specifically, to electrophotographic imaging members having a charge transport layer comprising mixtures of at least four different symmetric and/or unsymmetric charge transport components which are less susceptible to crystallization in polymer binders, and to processes for forming images on the member.
Numerous imaging members for electrostatographic imaging systems are known including selenium, selenium alloys, such as, arsenic selenium alloys, layered inorganic imaging and layered organic members. Examples of layered organic imaging members include those containing a change transporting layer and a charge generating layer. Thus, for example, an illustrative layered organic imaging member 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 transport layer can be overcoated with the photogenerator layer, or charge generator layer. Examples of generator layers that can be employed in these members include, for example, charge generator components, such as, selenium, cadmium sulfide, vanadyl phthalocyanine, x-metal free phthalocyanine, benzimidazole perylene (BZP), hydroxygallium phthalocyanine (HOGaPc), chlorogallium phthalocyanine, and trigonal selenium 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.
One problem encountered with photoreceptors comprising a charge generating layer and the charge transport layer is that the charge transport component consisting of small organic molecules dissolved in a polymer binder can result in the small molecule crystallizing with increasing concentrations in the polymer binder. This crystallization can result in non-uniformity of images, increased residual voltages, and the early development of dynamic fatigue charge transport layer cracking during, for example, photoreceptor belt machine function. High quality images are essential for digital copiers, duplicators, printers, and facsimile machines, particularly laser exposure machines that demand high resolution images.
There continues to be a need for improved imaging members, and improved imaging systems utilizing such members. Additionally, there continues to be a need for imaging members with improved lifetimes and mechanical function, and which members are economical to prepare and retain their properties over extended periods of time.
REFERENCES
In U.S. Pat. No. 4,410,616, to Griffiths, et al., issued Oct. 18, 1983, there is disclosed an improved ambi-polar photoresponsive device useful in imaging systems for the production of positive images, from either positive or negative originals, which device is comprised of: (a) supporting substrate, (b) a first photogenerating layer, (c) a charge transport layer, and (d) a second photogenerating layer, wherein the charge transport layer is comprised of a highly insulating polymer resin having dissolved therein components of an electrically active material of N,N′-diphenyl-N,N′-bis(“X substituted” phenyl)-(1,1,-biphenyl-4,4′-diamine wherein X is selected from the group consisting of alkyl and halogen.
U.S. Pat. No. 4,806,443 describes a charge transport layer including a polyether carbonate (PEC) obtained from the condensation of N,N′-diphenyl-N,N′bis(3-hydroxyphenyl)-(1,1′-biphenyl)-4,4′-diamine and diethylene glycol bischloroformate. U.S. Pat. No. 4,025,341 similarly describes a photoreceptor that includes a charge transport layer consisting of a mixture of polycarbonate and a low molecular weight photoconductive polymer from the condensation of a tertiary amine with an aldehyde. What is still desired is an improved material for a charge transport layer of an imaging member that exhibits excellent performance properties the same as or better than existing materials discussed above.
The entire disclosures of these patents are incorporated herein by reference.
BRIEF SUMMARY
Disclosed herein is an improved electrophotographic imaging member comprising a supporting substrate having an electrically conductive layer,
a charge blocking layer,
an optional adhesive layer,
a charge-generating layer,
a charge transporting layer comprising a synthesized mixture of at least four different symmetric and/or unsymmetric charge transport molecules represented by:
wherein R
1
, R
2
, R
3
, R
4
are aryl groups with, for example, from about 6 to about 30 carbon atoms, such as phenyl, tolyl, xylyl, butylphenyl, chlorophenyl, fluorophenyl, naphthyl, and the like; A is a aromatic group bridge connecting two nitrogen atoms, with, for example, from about 6 to about 30 carbon atoms, such as phenylene, biphenyl, bitolyl, terphenyl, and the like, and wherein in embodiments the aforementioned groups may be substituted with, for example, halogen, and a film forming binder.
Further disclosed herein is an improved electrophotographic imaging member for which photoinduced discharge characteristic (PIDC) curves do not change with time or repeated use.
By the use of the disclosed synthesized mixture of symmetric and/or unsymmetric charge transport molecules in the charge transport layer of the present invention, a charge transport layer of an imaging member is achieved that has excellent hole transporting performance and wear resistance, and that is able to be coated onto the imaging member structure using known conventional methods.
Aspects illustrated herein relate to;
a substrate,
a charge blocking layer,
an optional adhesive layer,
a charge generating layer,
a charge transport layer comprising: a synthesized mixture of at least four different symmetric and/or unsymmetric charge transport molecules.
The disclosed mixture of symmetric and/or unsymmetric charge transport molecules can be readily synthesized by the preparative process illustrated, for example, in Scheme I:
wherein R
1
, R
2
, R
3
, R
4
are aryl groups with, for example, from about 6 to about 30 carbon atoms, such as phenyl, tolyl, xylyl, butylphenyl, chlorophenyl, fluorophenyl, naphthyl, and the like; A is a aromatic group bridge connecting two nitrogen atoms, with, for example, from about 6 to about 30 carbon atoms, such as phenylene, biphenyl, bitolyl, terphenyl, and the like, and wherein in embodiments the aforementioned groups may be substituted with, for example, halogen.
As indicated in Scheme I, the mixture of symmetric and/or unsymmetric charge transport molecules are prepared by, for example, an Ullmann condensation of the diarylamine intermediate with diiodide intermediate. The reaction is generally accomplished in an inert solvent, such as dodecane, tridecane, mesitylene, xylene, toluene, and the like, at a temperature ranging from about 100 degrees Celsius to about 280 degrees Celsius, and in embodiments from about 110 degrees Celsius to about 250 degrees Celsius. Any suitable catalysts for Ullmann condensation, including copper powder, cuprous iodide, cupric sulfate, tris(dibenzylideneacetone)dipalladium(0), and the like, may be employed for the process of the present invention. The reaction can be accelerated with an addition, in an effective amount, of a base such as an alkaline metal hydroxide, or carbonate including potassium hydroxide, potassium carbonate, sodium hydroxide, sodium carbonate, and the like. The product is isolated by known means, for example, by filtration, chromatography and distillation.
The imaging member may be imaged by depositing a uniform electrostatic charge on the imaging member, exposing the imaging member to activating radiation in image configuration to form an electrostatic latent image,
Fu Min-Hong
Fuller Timothy J.
Prosser Dennis J.
Tong Yuhua
VanDusen Susan M.
Dote Janis L.
Oliff & Berridg,e PLC
Xerox Corporation
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