Patent Application
20080057421
An imaging member was prepared by providing a 0.02 micrometer thick titanium layer coated (the coater device) on a biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000) having a thickness of 3.5 mils, and applying thereon, with a gravure applicator, a solution containing 50 grams of 3-amino-propyltriethoxysilane, 41.2 grams of water, 15 grams of acetic acid, 684.8 grams of denatured alcohol, and 200 grams of heptane. This layer was then dried for about 5 minutes at 135° C. in the forced air dryer of the coater. The resulting blocking layer had a dry thickness of 500 Angstroms. An adhesive layer was then prepared by applying a wet coating over the blocking layer using a gravure applicator, and which adhesive layer contains 0.2 percent by weight based on the total weight of the solution of the copolyester adhesive (ARDEL™ D100 available from Toyota Hsutsu Inc.) in a 60:30:10 volume ratio mixture of tetrahydrofuran/monochlorobenzene/methylene chloride. The adhesive layer was then dried for about 5 minutes at 135° C. in the forced air dryer of the coater. The resulting adhesive layer had a dry thickness of 200 Angstroms.
A photogenerating layer dispersion was prepared by introducing 0.45 grams of the known polycarbonate LUPILON™ 200 (PCZ-200) or POLYCARBONATE Z™, weight average molecular weight of 20,000, available from Mitsubishi Gas Chemical Corporation, and 50 milliliters of tetrahydrofuran into a 4 ounce glass bottle. To this solution were added 2.4 grams of benzimidazole perylene (BZP) and 300 grams of ⅛ inch (3.2 millimeters) diameter stainless steel shot. This mixture was then placed on a ball mill for 8 hours. Subsequently, 2.25 grams of PCZ-200 were dissolved in 46.1 grams of tetrahydrofuran, and added to the BZP dispersion. This slurry was then placed on a shaker for 10 minutes. The resulting dispersion was, thereafter, applied to the above adhesive interface with a Bird applicator to form a photogenerating layer having a wet thickness of 0.25 mil. A strip about 10 millimeters wide along one edge of the substrate web bearing the blocking layer and the adhesive layer was deliberately left uncoated by any of the photogenerating layer material to facilitate adequate electrical contact by the ground strip layer that was applied later. The photogenerating layer was dried at 120° C. for 1 minute in a forced air oven to form a dry photogenerating layer having a thickness of 0.4 micrometer.
The resulting imaging member web was then overcoated with a two-layer charge transport layer. Specifically, the photogenerating layer was overcoated with a charge transport layer (the bottom layer) in contact with the photogenerating layer. The bottom layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 1:1 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, and MAKROLON® 5705, a known polycarbonate resin having a molecular weight average of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G. The resulting mixture was then dissolved in methylene chloride to form a solution containing 15 percent by weight solids. This solution was applied on the photogenerating layer to form the bottom layer coating that upon drying (120° C. for 1 minute) had a thickness of 14.5 microns. During this coating process, the humidity was equal to or less than 15 percent.
The bottom layer of the charge transport layer was then overcoated with a top layer. The charge transport layer solution of the top layer was prepared as described above for the bottom layer. This solution was applied on the bottom layer of the charge transport layer to form a coating that upon drying (120° C. for 1 minute) had a thickness of 14.5 microns. During this coating process, the humidity was equal to or less than 15 percent.
An imaging member was prepared by repeating the process of Comparative Example 1 except that the top layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.04 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The resulting mixture was dissolved in methylene chloride to form a solution containing 15 percent by weight solids.
An imaging member is prepared by repeating the process of Example I except that the bottom layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 1:1:0.2 N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, MAKROLON® 5705, a polycarbonate resin having a weight average molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids.
The above two photoreceptor devices (Comparative Example 1 and Example I) were tested in a scanner set to obtain photoinduced discharge cycles, sequenced at one charge-erase cycle followed by one charge-expose-erase cycle, wherein the light intensity was incrementally increased with cycling to produce a series of photoinduced discharge characteristic curves from which the photosensitivity and surface potentials at various exposure intensities are measured. Additional electrical characteristics were obtained by a series of charge-erase cycles with incrementing surface potential to generate several voltage versus charge density curves. The scanner was equipped with a scorotron set to a constant voltage charging at various surface potentials. The devices were tested at surface potentials of 500 volts with the exposure light intensity incrementally increased by means of regulating a series of neutral density filters; the exposure light source was a 670 nanometer light emitting diode. The xerographic simulation was completed in an environmentally controlled light tight chamber at ambient conditions (40 percent relative humidity and 22° C.). The devices were also cycled to 3,000 cycles electrically with charge-discharge-erase. Four photoinduced discharge characteristic (PIDC) curves were generated, one for each of the above prepared photoconductors at both cycle=0 and cycle=3,000, and where V equals volt. The results are summarized as follows.
In embodiments, there is disclosed a number of improved characteristics for the photoconductive members as determined by the generation of known PIDC curves, such as minimization or prevention of Vr cycle up by the physical doping of the silanol into the charge transport layer. More specifically, photosensitivity is measured as the initial slope of a photoinduced discharge characteristic (PDIC) curve, while Vr is the residual potential after erase, used to characterize the PIDC. Incorporation of the silanol into the charge transport layer increased the photosensitivity by about 20 percent, reduced Vr by about 40 volts, and prevented photoconductor cycle up with extended cycling.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
