Patent Grant
7968261
Copending U.S. application Ser. No. 12/129,958, U.S. Publication No. 20090297964 on Anthracene Containing Photoconductors, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,965, U.S. Publication No. 20090297965 on Ferrocene Containing Photoconductors, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,969, U.S. Publication No. 20090297966 on Amine Phosphate Containing Photogenerating Layer Photoconductors, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,943, U.S. Publication No. 20090297961 on Phenol Polysulfide Containing Photogenerating Layer Photoconductors, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,977, U.S. Publication No. 20090297967 on Phosphonate Hole Blocking Layer Photoconductors, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,948, U.S. Publication No. 20090297962 on Aminosilane and a Self Crosslinking Acrylic Resin Hole Blocking Layer Photoconductors, filed May 30 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,952, U.S. Publication No. 20090297963 on Backing Layer Containing Photoconductor, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,989, U.S. Publication No. 20090297969 on Polymer Anticurl Backside Coating (ACBC) Photoconductors, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
Copending U.S. application Ser. No. 12/129,995, U.S. Publication No. 20090297232 on Polyimide Intermediate Transfer Components, filed May 30, 2008, the disclosure of which is totally incorporated herein by reference.
U.S. application Ser. No. 11/869,252, U.S. Publication No. 20090092911, filed Oct. 9, 2007, entitled Additive Containing Charge Transport Layer Photoconductors, the disclosure of which is totally incorporated herein by reference, illustrates a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the charge transport layer contains at least one ammonium salt.
U.S. application Ser. No. 11/869,265, now U.S. Pat. No. 7,709,168, filed Oct. 9, 2007, entitled Phosphonium Containing Charge Transport Layer Photoconductors, the disclosure of which is totally incorporated herein by reference, there is disclosed a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the at least one charge transport layer contains at least one phosphonium salt.
In copending U.S. application Ser. No. 12/059,573, U.S. Publication 20090246664, filed Mar. 31, 2008, entitled Oxadiazole Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, there is illustrated a photoconductor comprising an optional supporting substrate, a photogenerating layer, and at least one charge transport layer wherein at least one of the charge transport layers is comprised of at least one charge transport component, and where at least one of the photogenerating layer and the charge transport layer includes an oxadiazole.
In U.S. application Ser. No. 12/059,587, now U.S. Pat. No. 7,811,732, filed Mar. 31, 2008, entitled Titanocene Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, there is illustrated a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer wherein at least one of the charge transport layers is comprised of at least one charge transport component, and wherein at least one of the photogenerating layer and the charge transport layer includes a titanocene.
A number of the components, amounts of each, and layer thicknesses thereof of the above copending applications, such as the supporting substrates, resin binders, photogenerating layer components, antioxidants, charge transport components, hole blocking layer components, adhesive layers, and the like, may be selected for the photoconductors of the present disclosure in embodiments thereof.
This disclosure is generally directed to photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered rigid drum and flexible belt imaging members, or devices comprised of an optional supporting medium like a substrate, at least one of a photogenerating layer and a charge transport layer containing a zirconocene, including a plurality of charge transport layers, such as a first charge transport layer and a second charge transport layer, an optional adhesive layer, an optional hole blocking or undercoat layer, and an optional overcoating layer. At least one in embodiments refers, for example, to 1, 2, to from 1 to about 10, to from 2 to about 7; to from 2 to about 4, and the like. Moreover, the zirconocene additive can be added to the photogenerating layer or to at least one of the charge transport layers, and, for example, instead of being dissolved in the photogenerating layer dispersion or charge transport layer solution, the zirconocene can be added to the photogenerating layer or charge transport layer as a dopant, and more specifically, the zirconocene, can be added to the bottom charge transport layer.
Yet more specifically, there is disclosed a photoconductor comprised of a supporting substrate, a zirconocene containing photogenerating layer, or a zirconocene containing charge transport layer or charge transport layers, such as a first pass charge transport layer, a second pass charge transport layer, to primarily permit excellent photoconductor photosensitivites and an acceptable Vr and Vr cycle up.
The zirconocene additives or dopants which can be incorporated into the photogenerating layer, and which dopants function, for example, to passivate the photogenerating pigment surface by, for example, blocking or substantially blocking intrinsic free carriers, and preventing or minimizing external free carriers from attracting to the pigment surface, and thereby permitting photoconductors with minimal CDS (charge deficient spots), the control of PIDC, for example controlling, and more specifically, slowing the PIDC, especially in those situations where the photosensitivity of the photoconductor can be adjusted on line and automatically to a desired preselected value or amount, and which photosensitivity can be increased or decreased; and acceptable LCM characteristics, such as for example, acceptable lateral charge migration (LCM) resistance. Similarly, the zirconocene additive can be incorporated into the charge transport layer, and in embodiments there can be accomplished the on line and automatic addition of the zirconocene to this layer.
Also disclosed are methods of imaging and printing with the photoconductor devices illustrated herein. These methods generally involve the formation of an electrostatic latent image on the imaging member, followed by developing the image with a toner composition comprised, for example, of thermoplastic resin, colorant, such as pigment, charge additive, and surface additive, reference U.S. Pat. Nos. 4,560,635; 4,298,697 and 4,338,390, the disclosures of which are totally incorporated herein by reference, subsequently transferring the image to a suitable substrate, and permanently affixing the image thereto. In those environments wherein the device is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, flexible belts disclosed herein can be selected for the Xerox Corporation iGEN3® machines that generate with some versions over 100 copies per minute. Processes of imaging, especially xerographic imaging and printing, including digital, and/or color printing, are thus encompassed by the present disclosure. The imaging members are in embodiments sensitive in the wavelength region of, for example, from about 400 to about 900 nanometers, and in particular from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source. Moreover, the imaging members of this disclosure are useful in high resolution color xerographic applications, particularly high speed color copying and printing processes.
There is illustrated in U.S. Pat. No. 6,913,863, the disclosure of which is totally incorporated herein by reference, a photoconductive imaging member comprised of a hole blocking layer, a photogenerating layer, and a charge transport layer, and wherein the hole blocking layer is comprised of a metal oxide; and a mixture of a phenolic compound and a phenolic resin wherein the phenolic compound contains at least two phenolic groups.
Layered photoresponsive imaging members have been described in numerous U.S. patents, such as U.S. Pat. No. 4,265,990, the disclosure of which is totally incorporated herein by reference, wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer.
Further, in U.S. Pat. No. 4,555,463, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with a chloroindium phthalocyanine photogenerating layer. In U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with, for example, a perylene, pigment photogenerating component.
Illustrated in U.S. Pat. No. 5,521,306, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of Type V hydroxygallium phthalocyanine comprising the in situ formation of an alkoxy-bridged gallium phthalocyanine dimer, hydrolyzing the dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product to Type V hydroxygallium phthalocyanine.
Illustrated in U.S. Pat. No. 5,482,811, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of hydroxygallium phthalocyanine photogenerating pigments which comprises hydrolyzing a gallium phthalocyanine precursor pigment by dissolving the hydroxygallium phthalocyanine in a strong acid, and then reprecipitating the resulting dissolved pigment in basic aqueous media; removing any ionic species formed by washing with water; concentrating the resulting aqueous slurry comprised of water and hydroxygallium phthalocyanine to a wet cake; removing water from said slurry by azeotropic distillation with an organic solvent, and subjecting said resulting pigment slurry to mixing with the addition of a second solvent to cause the formation of said hydroxygallium phthalocyanine polymorphs.
Also, in U.S. Pat. No. 5,473,064, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of photogenerating pigments of hydroxygallium phthalocyanine Type V essentially free of chlorine, where a pigment precursor Type I chlorogallium phthalocyanine is prepared by the reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, present in an amount of from about 10 parts to about 100 parts, with 1,3-diiminoisoindolene (DI3) in an amount of from about 1 part to about 10 parts, for each part of gallium chloride that is reacted; hydrolyzing said pigment precursor chlorogallium phthalocyanine Type I by standard methods, for example acid pasting, whereby the pigment precursor is dissolved in concentrated sulfuric acid and then reprecipitated in a solvent, such as water, or a dilute ammonia solution, for example from about 10 to about 15 percent; and subsequently treating the resulting hydrolyzed pigment hydroxygallium phthalocyanine Type I with a solvent, such as N,N-dimethylformamide, present in an amount of from about 1 volume part to about 50 volume parts, for each weight part of pigment hydroxygallium phthalocyanine that is used by, for example, ball milling the Type I hydroxygallium phthalocyanine pigment in the presence of spherical glass beads, approximately 1 millimeter to 5 millimeters in diameter, at room temperature, about 25° C., for a period of from about 12 hours to about 1 week, and preferably about 24 hours.
The appropriate components, and processes of the above recited patents may be selected for the present disclosure in embodiments thereof.
Disclosed in embodiments are imaging members with many of the advantages illustrated herein, such as extended lifetimes of service of, for example, in excess of about 1,000,000 imaging cycles; excellent electrical characteristics; stable electrical properties; low image ghosting; low background and/or minimal charge deficient spots (CDS). Also disclosed are layered photoresponsive imaging members which are responsive to visible light and near infrared radiation of from about 700 to about 900 nanometers.
Additionally disclosed are flexible imaging members with optional hole blocking layers comprised of metal oxides, phenolic resins, and optional phenolic compounds, and which phenolic compounds contain at least two, and more specifically, two to ten phenol groups or phenolic resins with, for example, a weight average molecular weight ranging from about 500 to about 3,000 permitting, for example, a hole blocking layer with excellent efficient electron transport which usually results in a desirable photoconductor low residual potential Vlow.
Aspects of the present disclosure relate to an imaging member comprising an optional supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and where the photogenerating layer or at least one charge transport layer contains a zirconocene additive; a photoconductor comprising an optional supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein at least one of the photogenerating layer and the charge transport layer includes a zirconocene; a photoconductor comprising a supporting substrate, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains at least one of an alkylzirconocene chloride and an alkylcyclopentadienylzirconium (IV) chloride; a photoconductor comprising a supporting substrate, a photogenerating layer, and a charge transport layer, and wherein the photogenerating layer or the charge transport layer contains at least one of cyclopentadienylzirconium (IV) trichloride, pentamethylcyclopentadienylzirconium (IV) trichloride, zirconocene dichloride, 1,1′-di(n-butyl)zirconocene dichloride, 1,1′-di(tert-butyl)zirconocene dichloride, 1,1′-diisopropylzirconocene dichloride, 1,1′-dimethylzirconocene dichloride, 1,1′-isopropylidenezirconocene dichloride, decamethylzirconocene dichloride, zirconocene bis(trifluoromethanesulfonate)tetrahydrofuran complex, and dimethylbis(pentamethylcyclopentadienyl)zirconium (IV).
Various effective amounts of the zirconocene can be included or added to each charge transport layer and/or to the photogenerating layer components, for example, of from about 10 parts per million (0.001 weight percent) to about 50,000 parts per million (5 weight percent); 0.001 to about 1 weight percent, from about 0.005 to about 0.1 weight percent, or similar amounts in the charge transport layer or layers; and from about 0.01 to about 5 weight percent, from about 0.05 to about 0.5 weight percent, or similar amounts in the photogenerating layer, and wherein the photogenerating layer and at least one charge transport layer include a resin binder; wherein the at least one charge transport layer is from 2 to about 7, and the photogenerating layer is situated between the substrate and the at least one charge transport layer; a drum, or flexible imaging member comprising a supporting substrate, a photogenerating layer, and at least two charge transport layers each of which contain a zirconocene. In embodiments thereof, there is disclosed a photoconductive imaging member comprised of a supporting substrate, a photogenerating layer thereover, a charge transport layer, and an overcoat charge transport layer; a photoconductive member with a photogenerating layer of a thickness of from about 0.1 to about 10 microns, at least one transport layer each of a thickness of from about 5 to about 100 microns; a xerographic imaging apparatus containing a charging component, a development component, a transfer component, and a fixing component, and wherein the apparatus contains a photoconductive imaging member comprised of a supporting substrate, and thereover a layer comprised of a photogenerating pigment and a charge transport layer or layers, and thereover an overcoat charge transport layer, and where the transport layer is of a thickness of from about 10 to about 75 microns; a member wherein the zirconocene or mixtures thereof is present in an amount of from about 0.001 to about 5 weight percent, or from about 0.01 to about 0.1 weight percent; a member wherein the photogenerating layer contains a photogenerating pigment present in an amount of from about 10 to about 95 weight percent; a member wherein the thickness of the photogenerating layer is from about 0.2 to about 4 microns; a member wherein the photogenerating layer contains an inactive polymer binder; a member wherein the binder is present in an amount of from about 20 to about 90 percent by weight, and wherein the total of all layer components is about 100 percent; a member wherein the photogenerating component is a hydroxygallium phthalocyanine or a titanyl phthalocyanine that absorbs light of a wavelength of from about 370 to about 950 nanometers; an imaging member wherein the supporting substrate is comprised of a conductive substrate comprised of a metal; an imaging member wherein the conductive substrate is aluminum, aluminized polyethylene terephthalate or titanized polyethylene terephthalate; an imaging member wherein the photogenerating resinous binder is selected from the group consisting of known suitable polymers like polyesters, polyvinyl butyrals, polycarbonates, polystyrene-b-polyvinyl pyridine, and polyvinyl formals; an imaging member wherein the photogenerating pigment is a metal free phthalocyanine; a photoconductor wherein each of the charge transport layers, especially a first and second layer, comprises
wherein X is selected from the group consisting of at least one of alkyl, alkoxy, and halogen such as methyl and chloride; and in embodiments where there is a total of four X substituents on each of the four terminating rings; an imaging member wherein alkyl and alkoxy contain from about 1 to about 15 carbon atoms; an imaging member wherein alkyl contains from about 1 to about 5 carbon atoms; an imaging member wherein alkyl is methyl; an imaging member wherein each of or at least one of the charge transport layers, especially a first and second charge transport layer, comprises
wherein X, Y and Z are independently selected from the group comprised of at least one of alkyl, alkoxy, aryl, and halogen, and in embodiments Z can be present, Y can be present or both Y and Z are present; or wherein the charge transport component is
wherein X and Y are independently alkyl, alkoxy, aryl, a halogen, or mixtures thereof, an imaging member and wherein, for example, alkyl and alkoxy contains from about 1 to about 15 carbon atoms; alkyl contains from about 1 to about 5 carbon atoms; and wherein the resinous binder is selected from the group consisting of polycarbonates, polyarylates and polystyrene; an imaging member wherein the photogenerating pigment present in the photogenerating layer is comprised of chlorogallium phthalocyanine, titanyl phthalocyanine or Type V hydroxygallium phthalocyanine prepared by hydrolyzing a gallium phthalocyanine precursor by dissolving the hydroxygallium phthalocyanine in a strong acid, and then reprecipitating the resulting dissolved precursor in a basic aqueous media; removing the ionic species formed by washing with water; concentrating the resulting aqueous slurry comprised of water and hydroxygallium phthalocyanine to a wet cake; removing water from the wet cake by drying; and subjecting the resulting dry pigment to mixing with the addition of a second solvent to cause the formation of the hydroxygallium phthalocyanine; an imaging member wherein the Type V hydroxygallium phthalocyanine has major peaks, as measured with an X-ray diffractometer, at Bragg angles (2 theta+/−0.2°) 7.4, 9.8, 12.4, 16.2, 17.6, 18.4, 21.9, 23.9, 25.0, 28.1 degrees, and the highest peak at 7.4 degrees; a method of imaging wherein the imaging member is exposed to light of a wavelength of from about 400 to about 950 nanometers; a member wherein the photogenerating layer is situated between the substrate and the charge transport; a member wherein the charge transport layer is situated between the substrate and the photogenerating layer, and wherein the number of charge transport layers is 2; a member wherein the photogenerating layer is of a thickness of from about 0.3 to about 25 microns; a member wherein the photogenerating component amount is from about 0.05 weight percent to about 20 weight percent, and wherein the photogenerating pigment is dispersed in from about 10 weight percent to about 80 weight percent of a polymer binder; a member wherein the thickness of the photogenerating layer is from about 0.1 to about 11 microns; a member wherein the photogenerating and charge transport layer components are contained in a polymer binder; a member wherein the binder is present in an amount of from about 50 to about 90 percent by weight, and wherein the total of the layer components is about 100 percent; a photoconductor wherein the photogenerating resinous binder is selected from the group consisting of at least one of polyesters, polyvinyl butyrals, polycarbonates, polystyrene-b-polyvinyl pyridine, and polyvinyl formals; an imaging member wherein the photogenerating component is Type V hydroxygallium phthalocyanine, titanyl phthalocyanine, chlorogallium phthalocyanine, or mixtures thereof, and the charge transport layer contains a hole transport of N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-m-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-o-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2-ethyl-6-methylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-diphenyl-N,N′-bis(3-chlorophenyl)-[p-terphenyl]-4,4″-diamine molecules, and wherein the hole transport resinous binder is selected from the group consisting of polycarbonates and polystyrene; an imaging member wherein the photogenerating layer contains a metal free phthalocyanine; an imaging member wherein the photogenerating layer contains an alkoxygallium phthalocyanine; a photoconductive imaging member with a blocking layer contained as a coating on a substrate, and an adhesive layer coated on the blocking layer; an imaging member further containing an adhesive layer and a hole blocking layer; a color method of imaging which comprises generating an electrostatic latent image on the imaging member, developing the latent image, transferring, and fixing the developed electrostatic image to a suitable substrate; photoconductive imaging members comprised of a supporting substrate, a photogenerating layer, a hole transport layer and a top overcoat layer in contact with the hole transport layer or in embodiments in contact with the photogenerating layer, and in embodiments wherein a plurality of charge transport layers are selected, such as for example, from 2 to about 10, and more specifically, 2 may be selected; and a photoconductive imaging member comprised of an optional supporting substrate, a photogenerating layer, and a first, second, and third charge transport layer.
In embodiments, the zirconocenes selected for the photogenerating layer, charge transport layer, or both of these layers are comprised of at least one cyclopentadienyl (Cp) or substituted cyclopentadienyl anion bound to a zirconium center in the oxidation state IV.
Examples of zirconocenes which are soluble or substantially soluble in a number of solvents inclusive in embodiments of the solvents selected for the photogenerating layer dispersion or charge transport layer solution, such as methylene chloride, tetrahydofuran, and the like, include cyclopentadienylzirconium (IV) trichloride, pentamethylcyclopentadienylzirconium (IV) trichloride, zirconocene dichloride, 1,1′-di(n-butyl)zirconocene dichloride, 1,1′-di(tert-butyl)zirconocene dichloride, 1,1′-diisopropylzirconocene dichloride, 1,1′-dimethylzirconocene dichloride, 1,1′-isopropylidenezirconocene dichloride, decamethylzirconocene dichloride, zirconocene bis(trifluoromethanesulfonate)tetrahydrofuran complex, and dimethylbis(pentamethylcyclopentadienyl)zirconium (IV), and the like.
Zirconocenes that may be selected for the photogenerating layer, and/or the charge transport layer or charge transport layers, can be represented by at least one of the following
There can be selected for the photoconductors disclosed herein a number of known layers, such as substrates, photogenerating layers, charge transport layers, hole blocking layers, adhesive layers, protective overcoat layers, and the like. Examples, thicknesses, specific components of many of these layers include the following.
The thickness of the photoconductor substrate layer depends on many factors, including economical considerations, electrical characteristics, adequate flexibility, availability and cost of the specific components for each layer, and the like, thus this layer may be of a substantial thickness, for example about 3,000 microns, such as from about 1,000 to about 2,000 microns, from about 500 to about 1,000 microns, or from about 300 to about 700 microns, (“about” throughout includes all values in between the values recited) or of a minimum thickness. In embodiments, the thickness of this layer is from about 75 microns to about 300 microns, or from about 100 to about 150 microns.
The photoconductor substrate may be opaque or substantially transparent, and may comprise any suitable material having the required mechanical properties. Accordingly, the substrate may comprise a layer of an electrically nonconductive or conductive material such as an inorganic or an organic composition. As electrically nonconducting materials, there may be employed various resins known for this purpose including polyesters, polycarbonates, polyamides, polyurethanes, and the like, which are flexible as thin webs. An electrically conducting substrate may be any suitable metal of, for example, aluminum, nickel, steel, copper, and the like, or a polymeric material, as described above, filled with an electrically conducting substance, such as carbon, metallic powder, and the like, or an organic electrically conducting material. The electrically insulating or conductive substrate may be in the form of an endless flexible belt, a web, a rigid cylinder, a sheet, and the like. The thickness of the substrate layer depends on numerous factors, including strength desired, and economical considerations. For a drum, this layer may be of a substantial thickness of, for example, up to many centimeters or of a minimum thickness of less than a millimeter. Similarly, a flexible belt may be of a substantial thickness of, for example, about 250 micrometers, or of a minimum thickness of less than about 50 micrometers, provided there are no adverse effects on the final electrophotographic device.
In embodiments where the substrate layer is not conductive, the surface thereof may be rendered electrically conductive by an electrically conductive coating. The conductive coating may vary in thickness over substantially wide ranges depending upon the optical transparency, degree of flexibility desired, and economic factors.
Illustrative examples of substrates are as illustrated herein, and more specifically, supporting substrate layers selected for the photoconductors of the present disclosure, and which substrates can be opaque or substantially transparent comprise a layer of insulating material including inorganic or organic polymeric materials, such as MYLAR® a commercially available polymer, MYLAR® containing titanium, a layer of an organic or inorganic material having a semiconductive surface layer, such as indium tin oxide, or aluminum arranged thereon, or a conductive material inclusive of aluminum, chromium, nickel, brass, or the like. The substrate may be flexible, seamless, or rigid, and may have a number of many different configurations, such as for example, a plate, a cylindrical drum, a scroll, an endless flexible belt, and the like. In embodiments, the substrate is in the form of a seamless flexible belt. In some situations, it may be desirable to coat on the back of the substrate, particularly when the substrate is a flexible organic polymeric material, an anticurl layer, such as for example polycarbonate materials commercially available as MAKROLON®.
Generally, the photogenerating layer can contain known photogenerating pigments, such as metal phthalocyanines, metal free phthalocyanines, alkylhydroxyl gallium phthalocyanines, hydroxygallium phthalocyanines, chlorogallium phthalocyanines, perylenes, especially bis(benzimidazo)perylene, titanyl phthalocyanines, and the like, and more specifically, vanadyl phthalocyanines, Type V hydroxygallium phthalocyanines, high sensitivity titanyl phthalocyanines, and inorganic components such as selenium, selenium alloys, and trigonal selenium. The photogenerating pigment can be dispersed in a resin binder similar to the resin binders selected for the charge transport layer, or alternatively no resin binder need be present. Generally, the thickness of the photogenerating layer depends on a number of factors, including the thicknesses of the other layers and the amount of photogenerating material contained in the photogenerating layer. Accordingly, this layer can be of a thickness of, for example, from about 0.05 micron to about 10 microns, and more specifically, from about 0.25 micron to about 2 microns when, for example, the photogenerating compositions are present in an amount of from about 30 to about 75 percent by volume. The maximum thickness of this layer in embodiments is dependent primarily upon factors, such as photosensitivity, electrical properties, and mechanical considerations.
The photogenerating composition or pigment can be present in a resinous binder composition in various amounts inclusive of up to 100 percent by weight. Generally, however, from about 5 percent by volume to about 95 percent by volume of the photogenerating pigment is dispersed in about 95 percent by volume to about 5 percent by volume of the resinous binder, or from about 20 percent by volume to about 30 percent by volume of the photogenerating pigment is dispersed in about 70 percent by volume to about 80 percent by volume of the resinous binder composition. In one embodiment, about 90 percent by volume of the photogenerating pigment is dispersed in about 10 percent by volume of the resinous binder composition, and which resin may be selected from a number of known polymers, such as poly(vinyl butyral), poly(vinyl carbazole), polyesters, polycarbonates, poly(vinyl chloride), polyacrylates and methacrylates, copolymers of vinyl chloride and vinyl acetate, phenolic resins, polyurethanes, poly(vinyl alcohol), polyacrylonitrile, polystyrene, and the like. It is desirable to select a coating solvent that does not substantially disturb or adversely affect the other previously coated layers of the device. Examples of coating solvents for the photogenerating layer are ketones, alcohols, aromatic hydrocarbons, halogenated aliphatic hydrocarbons, ethers, amines, amides, esters, and the like. Specific solvent examples are cyclohexanone, acetone, methyl ethyl ketone, methanol, ethanol, butanol, amyl alcohol, toluene, xylene, chlorobenzene, carbon tetrachloride, chloroform, methylene chloride, trichloroethylene, tetrahydrofuran, dioxane, diethyl ether, dimethyl formamide, dimethyl acetamide, butyl acetate, ethyl acetate, methoxyethyl acetate, and the like.
The photogenerating layer may comprise amorphous films of selenium and alloys of selenium and arsenic, tellurium, germanium, and the like, hydrogenated amorphous silicon and compounds of silicon and germanium, carbon, oxygen, nitrogen, and the like fabricated by vacuum evaporation or deposition. The photogenerating layers may also comprise inorganic pigments of crystalline selenium and its alloys; Groups II to VI compounds; and organic pigments such as quinacridones, polycyclic pigments such as dibromo anthanthrone pigments, perylene and perinone diamines, polynuclear aromatic quinones, azo pigments including bis-, tris- and tetrakis-azos, and the like dispersed in a film forming polymeric binder and fabricated by solvent coating techniques.
In embodiments, examples of photogenerating layer binders are thermoplastic and thermosetting resins, such as polycarbonates, polyesters, polyamides, polyurethanes, polystyrenes, polyarylethers, polyarylsulfones, polybutadienes, polysulfones, polyethersulfones, polyethylenes, polypropylenes, polyimides, polymethylpentenes, poly(phenylene sulfides), poly(vinyl acetate), polysiloxanes, polyacrylates, polyvinyl acetals, polyamides, polyimides, amino resins, phenylene oxide resins, terephthalic acid resins, phenoxy resins, epoxy resins, phenolic resins, polystyrene, and acrylonitrile copolymers, poly(vinyl chloride), vinyl chloride and vinyl acetate copolymers, acrylate copolymers, alkyd resins, cellulosic film formers, poly(amideimide), styrenebutadiene copolymers, vinylidene chloride-vinyl chloride copolymers, vinyl acetate-vinylidene chloride copolymers, styrene-alkyd resins, poly(vinyl carbazole), and the like. These polymers may be block, random, or alternating copolymers.
Various suitable and conventional known processes may be used to mix, and thereafter apply the photogenerating layer coating mixture, like spraying, dip coating, roll coating, wire wound rod coating, vacuum sublimation, and the like. For some applications, the photogenerating layer may be fabricated in a dot or line pattern. Removal of the solvent of a solvent-coated layer may be effected by any known conventional techniques such as oven drying, infrared radiation drying, air drying, and the like.
The final dry thickness of the photogenerating layer is as illustrated herein, and can be, for example, from about 0.01 to about 30 microns after being dried at, for example, about 40° C. to about 150° C. for about 15 to about 90 minutes. More specifically, a photogenerating layer of a thickness, for example, of from about 0.1 to about 30, or from about 0.5 to about 2 microns can be applied to or deposited on the substrate, on other surfaces in between the substrate and the charge transport layer, and the like. A charge blocking layer or hole blocking layer may optionally be applied to the electrically conductive surface prior to the application of a photogenerating layer. When desired, an adhesive layer may be included between the charge blocking or hole blocking layer or interfacial layer and the photogenerating layer. Usually, the photogenerating layer is applied onto the adhesive layer, and a charge transport layer or plurality of charge transport layers are formed on the photogenerating layer. This structure may have the photogenerating layer on top of or below the charge transport layer.
In embodiments, a suitable known adhesive layer can be included in the photoconductor. Typical adhesive layer materials include, for example, polyesters, polyurethanes, and the like. The adhesive layer thickness can vary and in embodiments is, for example, from about 0.05 micrometer (500 Angstroms) to about 0.3 micrometer (3,000 Angstroms). The adhesive layer can be deposited on the hole blocking layer by spraying, dip coating, roll coating, wire wound rod coating, gravure coating, Bird applicator coating, and the like. Drying of the deposited coating may be effected by, for example, oven drying, infrared radiation drying, air drying, and the like.
As an optional adhesive layer or layers usually in contact with or situated between the hole blocking layer and the photogenerating layer, there can be selected various known substances inclusive of copolyesters, polyamides, poly(vinyl butyral), poly(vinyl alcohol), polyurethane, and polyacrylonitrile. This layer is, for example, of a thickness of from about 0.001 micron to about 1 micron, or from about 0.1 to about 0.5 micron. Optionally, this layer may contain effective suitable amounts, for example from about 1 to about 10 weight percent, of conductive and nonconductive particles, such as zinc oxide, titanium dioxide, silicon nitride, carbon black, and the like, to provide, for example, in embodiments of the present disclosure further desirable electrical and optical properties.
The optional hole blocking or undercoat layer or layers for the imaging members of the present disclosure can contain a number of components including known hole blocking components, such as amino silanes, doped metal oxides, a metal oxide like titanium, chromium, zinc, tin and the like; a mixture of phenolic compounds and a phenolic resin or a mixture of two phenolic resins, and optionally a dopant such as SiO2. The phenolic compounds usually contain at least two phenol groups, such as bisphenol A (4,4′-isopropylidenediphenol), E (4,4′-ethylidenebisphenol), F (bis(4-hydroxyphenyl)methane), M (4,4′-(1,3-phenylenediisopropylidene)bisphenol), P (4,4′-(1,4-phenylene diisopropylidene)bisphenol), S (4,4′-sulfonyldiphenol), and Z (4,4′-cyclohexylidenebisphenol); hexafluorobisphenol A (4,4′-(hexafluoro isopropylidene)diphenol), resorcinol, hydroxyquinone, catechin, and the like.
The hole blocking layer can be, for example, comprised of from about 20 weight percent to about 80 weight percent, and more specifically, from about 55 weight percent to about 65 weight percent of a suitable component like a metal oxide, such as TiO2, from about 20 weight percent to about 70 weight percent, and more specifically, from about 25 weight percent to about 50 weight percent of a phenolic resin; from about 2 weight percent to about 20 weight percent, and, more specifically, from about 5 weight percent to about 15 weight percent of a phenolic compound preferably containing at least two phenolic groups, such as bisphenol S, and from about 2 weight percent to about 15 weight percent, and more specifically, from about 4 weight percent to about 10 weight percent of a plywood suppression dopant, such as SiO2. The hole blocking layer coating dispersion can, for example, be prepared as follows. The metal oxide/phenolic resin dispersion is first prepared by ball milling or dynomilling until the median particle size of the metal oxide in the dispersion is less than about 10 nanometers, for example from about 5 to about 9. To the above dispersion are added a phenolic compound and dopant followed by mixing. The hole blocking layer coating dispersion can be applied by dip coating or web coating, and the layer can be thermally cured after coating. The hole blocking layer resulting is, for example, of a thickness of from about 0.01 micron to about 30 microns, and more specifically, from about 0.1 micron to about 8 microns. Examples of phenolic resins include formaldehyde polymers with phenol, p-tert-butylphenol, cresol, such as VARCUM™ 29159 and 29101 (available from OxyChem Company), and DURITE™ 97 (available from Borden Chemical); formaldehyde polymers with ammonia, cresol and phenol, such as VARCUM™ 29112 (available from OxyChem Company); formaldehyde polymers with 4,4′-(1-methylethylidene)bisphenol, such as VARCUM™ 29108 and 29116 (available from OxyChem Company); formaldehyde polymers with cresol and phenol, such as VARCUM™ 29457 (available from OxyChem Company), DURITE™ SD-423A, SD-422A (available from Borden Chemical); or formaldehyde polymers with phenol and p-tert-butylphenol, such as DURITE™ ESD 556C (available from Border Chemical).
The optional hole blocking layer may be applied to the substrate. Any suitable and conventional blocking layer capable of forming an electronic barrier to holes between the adjacent photoconductive layer (or electrophotographic imaging layer) and the underlying conductive surface of substrate may be selected.
A number of charge transport components can be included in the charge transport layer, which layer generally is of a thickness of from about 5 microns to about 75 microns, and more specifically, of a thickness of from about 10 microns to about 40 microns.
Examples of charge transport components are aryl amines of the following formulas/structures
wherein X is as illustrated herein such as alkyl, aryl, alkoxy or halo.
Moreover, the photogenerating layer can be comprised of a high sensitivity titanyl phthalocyanine component generated by the processes as illustrated in copending application U.S. application Ser. No. 10/992,500, U.S. Publication No. 20060105254, the disclosure of which is totally incorporated herein by reference.
A number of titanyl phthalocyanines, or oxytitanium phthalocyanines, are suitable photogenerating pigments known to absorb near infrared light around 800 nanometers and may exhibit improved sensitivity compared to other pigments, such as, for example, hydroxygallium phthalocyanine. Generally, titanyl phthalocyanine is known to have five main crystal forms known as Types I, II, III, X, and IV. For example, U.S. Pat. Nos. 5,189,155 and 5,189,156, the entire disclosures of which are incorporated herein by reference, disclose a number of methods for obtaining various polymorphs of titanyl phthalocyanine. Additionally, U.S. Pat. Nos. 5,189,155 and 5,189,156 are directed to processes for obtaining Types I, X, and IV phthalocyanines. U.S. Pat. No. 5,153,094, the entire disclosure of which is incorporated herein by reference, relates to the preparation of titanyl phthalocyanine polymorphs including Types I, II, III, and IV polymorphs. U.S. Pat. No. 5,166,339, the disclosure of which is totally incorporated herein by reference, discloses processes for preparing Types I, IV, and X titanyl phthalocyanine polymorphs, as well as the preparation of two polymorphs designated as Type Z-1 and Type Z-2.
To obtain a titanyl phthalocyanine-based photoreceptor having high sensitivity to near infrared light, it is believed of value to control not only the purity and chemical structure of the pigment, as is generally the situation with organic photoconductors, but also to prepare the pigment in a certain crystal modification. Consequently, it is still desirable to provide a photoconductor where the titanyl phthalocyanine is generated by a process that will provide high sensitivity titanyl phthalocyanines.
In embodiments, the Type V phthalocyanine pigment included in the photogenerating layer can be generated by dissolving Type I titanyl phthalocyanine in a solution comprising a trihaloacetic acid and an alkylene halide; adding the resulting mixture comprising the dissolved Type I titanyl phthalocyanine to a solution comprising an alcohol and an alkylene halide thereby precipitating a Type Y titanyl phthalocyanine; and treating the resulting Type Y titanyl phthalocyanine with monochlorobenzene.
With further respect to the titanyl phthalocyanines selected for the photogenerating layer, such phthalocyanines exhibit a crystal phase that is distinguishable from other known titanyl phthalocyanine polymorphs, and are designated as Type V polymorphs prepared by converting a Type I titanyl phthalocyanine to a Type V titanyl phthalocyanine pigment. The processes include converting a Type I titanyl phthalocyanine to an intermediate titanyl phthalocyanine, which is designated as a Type Y titanyl phthalocyanine, and then subsequently converting the Type Y titanyl phthalocyanine to a Type V titanyl phthalocyanine.
In one embodiment, the process comprises (a) dissolving a Type I titanyl phthalocyanine in a suitable solvent; (b) adding the solvent solution comprising the dissolved Type I titanyl phthalocyanine to a quenching solvent system to precipitate an intermediate titanyl phthalocyanine (designated as a Type Y titanyl phthalocyanine); and (c) treating the resultant Type Y phthalocyanine with a halo, such as, for example, monochlorobenzene to obtain a resultant high sensitivity titanyl phthalocyanine, which is designated herein as a Type V titanyl phthalocyanine. In another embodiment, prior to treating the Type Y phthalocyanine with a halo, such as monochlorobenzene, the Type Y titanyl phthalocyanine may be washed with various solvents including, for example, water, and/or methanol. The quenching solvents system to which the solution comprising the dissolved Type I titanyl phthalocyanine is added comprises, for example, an alkyl alcohol, and an alkylene halide.
Illustrated herein with reference to Type V TioPc is a process that provides a titanyl phthalocyanine having a crystal phase distinguishable from other known titanyl phthalocyanines. The titanyl phthalocyanine Type V prepared by a process according to the present disclosure is distinguishable from, for example, Type IV titanyl phthalocyanines in that a Type V titanyl phthalocyanine exhibits an X-ray powder diffraction spectrum having four characteristic peaks at 9.0°, 9.6°, 24.0°, and 27.2°, while Type IV titanyl phthalocyanines typically exhibit only three characteristic peaks at 9.6°, 24.0°, and 27.2°.
In a process embodiment for preparing a high sensitivity phthalocyanine in accordance with the present disclosure, a Type I titanyl phthalocyanine is dissolved in a suitable solvent. In embodiments, a Type I titanyl phthalocyanine is dissolved in a solvent comprising a trihaloacetic acid and an alkylene halide. The alkylene halide comprises, in embodiments, from about one to about six carbon atoms. An example of a suitable trihaloacetic acid includes, but is not limited to, trifluoroacetic acid. In one embodiment, the solvent for dissolving a Type I titanyl phthalocyanine comprises trifluoroacetic acid and methylene chloride. In embodiments, the trihaloacetic acid is present in an amount of from about one volume part to about 100 volume parts of the solvent, and the alkylene halide is present in an amount of from about one volume part to about 100 volume parts of the solvent. In one embodiment, the solvent comprises methylene chloride and trifluoroacetic acid in a volume-to-volume ratio of about 4 to 1. The Type I titanyl phthalocyanine is dissolved in the solvent by stirring for an effective period of time, such as, for example, for about 30 seconds to about 24 hours, at room temperature. The Type I titanyl phthalocyanine is dissolved by, for example, stirring in the solvent for about one hour at room temperature (about 25° C.). The Type I titanyl phthalocyanine may be dissolved in the solvent in either air or in an inert atmosphere (argon or nitrogen).
Typically, flexible photoreceptor belts are fabricated by depositing the various layers of photoactive coatings onto lengthy webs that are thereafter cut into sheets. The opposite ends of each photoreceptor sheet are overlapped and ultrasonically welded together to form an imaging belt. In order to increase throughput during the web coating operation, the webs to be coated have a width of twice the width of a final belt. After coating, the web is slit lengthwise and thereafter transversely cut into predetermined lengths to form photoreceptor sheets of precise dimensions that are eventually welded into belts. The web length in a coating run may be many thousands of feet long and the coating run may take more than an hour for each layer.
The following Examples are being submitted to illustrate embodiments of the present disclosure. These Examples are intended to be illustrative only, and are not intended to limit the scope of the present disclosure. Also, parts and percentages are by weight unless otherwise indicated. A Comparative Example and data are also provided.
(A) An imaging member or photoconductor was prepared by providing a 0.02 micrometer thick titanium layer coated (coater device used) on a biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000) having a thickness of 3.5 mils, and applying thereon, with a gravure applicator or an extrusion coater, 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 or an extrusion coater, and which adhesive layer contained 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 gram of the known polycarbonate IUPILON™ 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 hydroxygallium phthalocyanine (Type V), and 300 grams of ⅛ inch (3.2 millimeters) diameter stainless steel shot. The resulting 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 hydroxygallium phthalocyanine dispersion. The obtained 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 micron.
The resulting imaging member web was then overcoated with two charge transport layers. 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 by introducing into an amber glass bottle in a weight ratio of 0.35:0.65 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. The top layer solution was applied on the bottom layer of the charge transport layer to form a coating that upon drying (1 20° 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.
(B) A photoconductor was prepared by repeating the above part (A), except that there is excluded the top charge transport layer, and the thickness of the bottom charge transport layer is 29 microns.
A photoconductive member was prepared by repeating the process of Comparative Example 1 (A) except that there was included in the photogenerating layer 0.04 weight percent (400 ppm) of 1,1′-di(n-butyl)zirconocene dichloride.
A photoconductive member is prepared by repeating the process of Comparative Example 1 (B) except that there is included in the photogenerating layer 0.04 weight percent (400 ppm) of 1,1′-di(n-butyl)zirconocene dichloride.
A number of photoconductors are prepared by repeating the processes of Comparative Example 1 (A) and 1 (B) except that there is included in the photogenerating layer 0.04 weight percent of at least one of cyclopentadienylzirconium (IV) trichloride, pentamethylcyclopentadienylzirconium (IV) trichloride, zirconocene dichloride, 1,1′-di(tert-butyl)zirconocene dichloride, 1,1′-diisopropylzirconocene dichloride, 1,1′-dimethylzirconocene dichloride, 1,1′-isopropylidenezirconocene dichloride, decamethylzirconocene dichloride, zirconocene bis(trifluoromethanesulfonate)tetrahydrofuran complex, and dimethylbis(pentamethylcyclopentadienyl)zirconium (IV).
A photoconductive member was prepared by repeating the process of Comparative Example 1 (A) except that there was included in the bottom charge transport layer 0.004 weight percent (40 ppm) of 1,1′-di(n-butyl)zirconocene dichloride.
A photoconductive member is prepared by repeating the process of Comparative Example 1 (B) except that there is included in the charge transport layer 0.002 weight percent (20 ppm) of 1,1′-di(n-butyl)zirconocene dichloride.
A number of photoconductors are prepared by repeating the process of Comparative Example 1 (A) except that there is included in the bottom charge transport layer 0.004 weight percent of at least one of cyclopentadienylzirconium (IV) trichloride, pentamethylcyclopentadienylzirconium (IV) trichloride, zirconocene dichloride, 1,1′-di(tert-butyl)zirconocene dichloride, 1,1′-diisopropylzirconocene dichloride, 1,1′-dimethylzirconocene dichloride, 1,1′-isopropylidenezirconocene dichloride, decamethylzirconocene dichloride, zirconocene bis(trifluoromethane sulfonate)tetrahydrofuran complex, and dimethylbis(pentamethylcyclopentadienyl)zirconium (IV).
A number of photoconductors are prepared by repeating the process of Comparative Example 1 (B) except that there is included in charge transport layer 0.002 weight percent of at least one of cyclopentadienylzirconium (IV) trichloride, pentamethylcyclopentadienylzirconium (IV) trichloride, zirconocene dichloride, 1,1′-di(tert-butyl)zirconocene dichloride, 1,1′-diisopropylzirconocene dichloride, 1,1′-dimethylzirconocene dichloride, 1,1′-isopropylidenezirconocene dichloride, decamethylzirconocene dichloride, zirconocene bis(trifluoromethanesulfonate)tetrahydrofuran complex, and dimethylbis(pentamethylcyclopentadienyl)zirconium (IV).
The above prepared photoreceptor devices (Comparative Example 1 (A) and Examples I and IV) 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 photoconductors were tested at surface potentials of 400 volts with the exposure light intensity being incrementally increased by means of regulating a series of neutral density filters; the exposure light source was a 780 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 results are summarized in Table 1.
wherein dV/dX (in Vcm2/erg) is the photosensitivity as determined by the initial slope of the photoinduced discharge curve plotted as surface potential (in volts) versus exposure energy (in erg/cm2); V(2.2) is the surface potential of the photoconductors at an exposure energy of 2.2 ergs/cm2; and Verase is the surface potential of the photoconductors after they were subjected to an erase light of 680 nanometers at an intensity of about 100 to 150 ergs/cm2.
With incorporation of the zirconocene either in the bottom charge transport layer (Example IV) or the photogenerating layer (Example I), the PIDC was tuned to a slower value with decreased photosensitivity, increased V(2.2) and increased Verase. For example, with 40 ppm of the zirconocene in the bottom charge transport layer (Example IV), the photosensitivity was decreased by about 3 percent, and the V(2.2) was increased by about 30 V; with 400 ppm of the zirconocene in the photogenerating layer (Example I), the photosensitivity was decreased by about 6 percent, and the V(2.2) was increased by about 30 V. The incorporation of zirconocene can effectively adjust PIDC, thus providing a feasible approach for on-line tuning of the PIDC to achieve excellent photoconductor production or manufacturing yields.
More specifically, the yield for the Example I and IV photoconductor was increased, it is believed, by about 20 percent based on theoretical calculations as compared to that of Comparative Example 1 (A) where on-line tuning was not implemented.
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.
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