Patent Grant
8426092
In copending U.S. application Ser. No. 12/788,020, filed May 26, 2010, the disclosure of which is totally incorporated herein by reference, there is illustrated a photoconductor comprising a supporting substrate, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a polyalkylene glycol benzoate and a fluorinated polymer
U.S. application Ser. No. 12/550,498, entitled Plasticizer Containing Photoconductors, filed Aug. 31, 2009, illustrates a photoconductor comprising a substrate, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a cyclohexanedicarboxylate, such as diisononyl cyclohexanedicarboxylate.
U.S. application Ser. No. 12/471,311, entitled Flexible Imaging Members Having A Plasticized Imaging Layer, filed May 22, 2009, the disclosure of which is totally incorporated herein by reference, illustrates for example, a flexible imaging member comprising a flexible substrate; a charge generating layer disposed on the substrate; and at least one charge transport layer disposed on the charge generating layer, wherein the charge transport layer comprises a polycarbonate, N,N′-diphenyl-N,N′-di(3-methylphenyl)-1,1-biphenyl-4,4′-diamine, a first plasticizer or a second plasticizer, and further wherein the first plasticizer and the second plasticizer are miscible with both the polycarbonate and N,N′-diphenyl-N,N′-di(3-methylphenyl)-1,1-biphenyl-4,4′-diamine.
U.S. application Ser. No. 12/434,572 filed May 1, 2009, the disclosure of which is totally incorporated herein by reference, illustrates for example, a imaging member, like a photoconductor, comprising a substrate; a charge generating layer deposited on the substrate; and at least one charge transport layer deposited on the charge generating layer, wherein the charge transport layer comprises a polycarbonate, a charge transport compound of N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1-biphenyl-4,4′-diamine, and a liquid compound having a high boiling point, like above about 100 degrees Centigrade and further wherein the liquid compound is miscible with both the polycarbonate and N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1-biphenyl-4,4′-diamine.
Examples of plasticizers illustrated in the above appropriate copending applications are, for example, dioctyl phthalate, diallyl phthalate, liquid styrene dimer, and others as illustrated by the structure/formulas disclosed.
Illustrated in copending U.S. application Ser. No. 12/551,414 filed Aug. 31, 2009, is for example, a flexible imaging member comprising a flexible substrate; a charge generating layer contained on the charge generating layer, wherein the charge transport layer is formed from a binary solid solution of a charge transport component and a polycarbonate binder plasticized with a plasticizer mixture of a phthalate plasticizing liquid and a plasticizer compound.
Illustrated in copending U.S. application Ser. No. 12/551,440 filed Aug. 31, 2009, is a layered photoconductor that includes a charge transport layer generated with a polycarbonate plasticized with a number of materials of Formulas (I) to (VII) and Formulas (1) to (5).
Titanyl phthalocyanine components selected for photoconductors are illustrated in copending U.S. application Ser. No. 10/992,500, U.S. Publication No. 20060105254, the disclosures of which are totally incorporated herein by reference, discloses for example, a process for the preparation of a Type V titanyl phthalocyanine, comprising providing a Type I titanyl phthalocyanine; dissolving the Type I titanyl phthalocyanine in a solution comprising a trihaloacetic acid and an alkylene halide like methylene chloride; 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 Type Y titanyl phthalocyanine with monochlorobenzene to yield a Type V titanyl phthalocyanine.
The disclosures of each of the above identified patent applications are totally incorporated herein by reference.
A number of the components of the above cross referenced applications, such as the appropriate supporting substrates, resin binders, antioxidants, charge transport components, titanyl phthalocyanines, high photosensitivity titanyl phthalocyanines, such as Type V, hydroxygallium phthalocyanines, or chlorogallium phthalocyanines, and an adhesive layer, and the like, may be selected for the photoconductors and imaging members of the present disclosure in embodiments thereof.
This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like that can be selected for a number of systems, such as copiers and printers, especially xerographic copiers and printers inclusive of printers that generate color xerographic documents, and which printers can be selected for the office environment, and for production and commercial printing uses. More specifically, the present disclosure is directed to multilayered drums, or flexible belt imaging members or devices comprised of a supporting medium like a substrate, an optional ground plane layer, an optional hole blocking layer, a photogenerating layer, and a charge transport layer, including at least one or a plurality of charge transport layers, and wherein at least one charge transport layer is, for example, from 1 to about 7, from 1 to about 3, and one; and more specifically, a first charge transport layer and a second charge transport layer, and where a poly(imide-carbonate) polymer, especially a copolymer thereof, and a fluorinated material, such as a polytetrafluoroethylene (PTFE) are present in the charge transport layer that is in contact with the photogenerating layer. The poly(imide-carbonate) polymer and polytetrafluoroethylene containing photoconductors possess, in embodiments, excellent wear characteristics, and where the poly(imide-carbonate) polymer functions, for example, as a charge transport layer (CTL) first or second resin binder, and the second or first binder is, for example, a fluorinated polymer, such as polytetrafluoroethylene or in embodiments a polycarbonate and mixtures of polycarbonates and polytetrafluoroethylenes.
The photoconductors disclosed herein possess it is believed a number of advantages such as, in embodiments, the minimal wearing of the charge transport layer or layers especially in xerographic copying and printing systems; the minimization or substantial elimination of undesirable ghosting on developed images, such as xerographic images, including decreased ghosting at various relative humidities; excellent cyclic and stable electrical properties; minimal charge deficient spots (CDS); compatibility with the photogenerating and charge transport resin binders; extended xerographic biased charge roller wear characteristics, and acceptable lateral charge migration (LCM) characteristics, such as for example, excellent LCM resistance.
Yet more specifically, an advantage of the photoconductors in embodiments of the present disclosure is that the wear rates when selecting for the charge transport layer a fluorinated polymer, like PTFE and a poly(imide-carbonate) polymer mixture was from about 15 to about 20 nanometers/kilocycle, about 50 to about 70 percent of that of a PTFE charge transport layer (CTL) (with no poly(imide-carbonate) polymer, a wear rate of about 30 nanometers/kilocycle). The wear rate is measured using an in-house known wear fixture as illustrated herein.
Ghosting refers, for example, to when a photoconductor is selectively exposed to positive charges in a number of xerographic print engines, and where some of the positive charges enter the photoconductor and manifest themselves as a latent image in the subsequent printing cycles. This print defect can cause a change in the lightness of the half tones, and is commonly referred to as a “ghost” that is generated in the previous printing cycle. An example of a source of the positive charges is the stream of positive ions emitted from the transfer corotron. Since the paper sheets are situated between the transfer corotron and the photoconductor, the photoconductor is shielded from the positive ions from the paper sheets. In the areas between the paper sheets, the photoconductor is fully exposed, thus in this paper free zone the positive charges may enter the photoconductor. As a result, these charges cause a print defect or ghost in a half tone print if one switches to a larger paper format that covers the previous paper print free zone.
Excellent cyclic stability of the photoconductor refers, for example, to almost no or minimal change in a generated known photoinduced discharge curve (PIDC), especially no or minimal residual potential cycle up after a number of charge/discharge cycles of the photoconductor, for example about 100 kilocycles, or xerographic prints of, for example, from about 80 to about 100 kiloprints. Excellent color print stability refers, for example, to substantially no or minimal change in solid area density, especially in 60 percent halftone prints, and no or minimal random color variability from print to print after a number of xerographic prints, for example 50 kiloprints.
Also included within the scope of the present disclosure 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 each of these patents being totally incorporated herein by reference, subsequently transferring the toner image to a suitable image receiving substrate, and permanently affixing the image thereto. In those environments wherein the photoconductor 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, the flexible photoconductor belts disclosed herein can be selected for the Xerox Corporation iGEN® machines that generate with some versions over 110 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 color xerographic applications, particularly high-speed, for example at least 100 copies per minute, color copying and printing processes.
A number of layered photoconductors are known and have been described in numerous U.S. patents, and which patents disclose, for example, a photoconductor comprised of a supporting substrate, a photogenerating layer, and a charge transport layer, and where the photogenerating layer and charge transport layer include certain resin binders, such as polycarbonates, polyesters, and the like.
There is disclosed in U.S. Pat. No. 5,489,496; U.S. Pat. No. 4,579,801; U.S. Pat. No. 4,518,669; U.S. Pat. No. 4,775,605; U.S. Pat. No. 5,656,407; U.S. Pat. No. 5,641,599; U.S. Pat. No. 5,344,734; U.S. Pat. No. 5,721,080; and U.S. Pat. No. 5,017,449, U.S. Pat. No. 6,200,716; U.S. Pat. No. 6,180,309; and U.S. Pat. No. 6,207,334 various layered photoconductors.
Also, photoconductors that include therein undercoat or charge blocking layers are disclosed in U.S. Pat. No. 4,464,450; U.S. Pat. No. 5,449,573; U.S. Pat. No. 5,385,796; and U.S. Pat. No. 5,928,824.
Illustrated in U.S. Pat. No. 5,521,306 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 for use as a photogenerating pigment in a photoconductor.
Illustrated in U.S. Pat. No. 5,482,811 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 the slurry by azeotropic distillation with an organic solvent, and subjecting the resulting pigment slurry to mixing with the addition of a second solvent to cause the formation of the hydroxygallium phthalocyanine polymorphs.
Also, in U.S. Pat. No. 5,473,064 there is illustrated a process for the preparation of photogenerating pigments of hydroxygallium phthalocyanine Type V essentially free of chlorine, whereby a pigment precursor Type I chlorogallium phthalocyanine is prepared by reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, hydrolyzing the pigment precursor chlorogallium phthalocyanine Type I by standard methods, for example acid pasting, 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 to about 50 volume parts, and more specifically about 15 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 to 5 millimeters in diameter, at room temperature, about 25° C., for a period of from about 12 hours to about 1 week, and more specifically about 24 hours.
The appropriate components, such as the supporting substrates, the photogenerating layer components, the charge transport layer components, the overcoating layer components, and the like, of the above-recited patents, each of the disclosures thereof of which are totally incorporated herein by reference, may be selected for the photoconductors of the present disclosure in certain embodiments thereof.
Aspects of the present disclosure relate to a photoconductor comprising a supporting substrate, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a poly(imide-carbonate) polymer and a fluorinated polymer; a photoconductor comprised of a supporting substrate, a hole blocking layer thereover, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a poly(imide-carbonate) copolymer present in an amount of for example, from about 1 to about 15 weight percent, a polytetrafluoroethylene present for example, in an amount of from about 1 or about 2 to about 12 weight percent and a polycarbonate present for example, in an amount of from about 40 to about 70 weight percent; a photoconductor comprised in sequence of a photogenerating layer comprised of a photogenerating pigment, a hole blocking layer, an adhesive layer, and a charge transport layer, and wherein the charge transport layer is comprised of a charge transport component such as an aryl amine of the formulas illustrated herein, a first resin binder, a second polyamide-carbonate) copolymer resin binder and a fluorinated polymer selected for example, from the group consisting of polytetrafluoroethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, a copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether), a copolymer of tetrafluoroethylene and perfluoro(ethyl vinyl ether), a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether), and a copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride; a photoconductor comprising an optional supporting substrate, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a poly(imide-carbonate) polymer, such as those poly(imide-carbonate) polymers illustrated in U.S. Pat. Nos. 6,214,505 and 6,309,785, the disclosures of which are totally incorporated herein by reference in their entirety, and a fluorinated polymer; a photoconductor comprised of a supporting substrate, a hole blocking layer thereover, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a poly(imide-carbonate) polymer present in an amount of from about 1 to about 30 weight percent, and a polytetrafluoroethylene present in an amount of from about 1 or about 2 to about 15 weight percent; a photoconductor comprised in sequence of a photogenerating layer comprised of a photogenerating pigment, a hole blocking layer, an adhesive layer, and a charge transport layer, and wherein the charge transport layer is comprised of a charge transport component, a first resin binder of a polycarbonate polymer selected from the group consisting of poly(4,4′-isopropylidene-diphenylene carbonate) (also referred to as bisphenol-A-polycarbonate), poly(4,4′-cyclohexylidine diphenylene carbonate) (also referred to as bisphenol-Z-polycarbonate), poly(4,4′-isopropylidene-3,3′-dimethyl-diphenyl carbonate) (also referred to as bisphenol-C-polycarbonate), and the like and mixtures thereof, a second resin binder of a poly(imide-carbonate) polymer, and a third fluorinated polymer binder and lubricant selected from the group consisting of polytetrafluoroethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, a copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether), a copolymer of tetrafluoroethylene and perfluoro(ethyl vinyl ether), a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether), and a copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride and the like and mixtures thereof; a photoconductor comprising a substrate, a photogenerating layer, and a charge transport layer, and wherein the charge transport layer contains a charge transport component, such as an aryl amine and other know charge and hole transport components, and a mixture of a polycarbonate, such as a bisphenol-Z-polycarbonate (PCZ), a fluorinated polymer, such as a polytetrafluoroethylene (PTFE) and a poly(imide-carbonate) polymer; a photoconductor comprising a substrate, an undercoat layer thereover, a photogenerating layer, and at least one charge transport layer, and wherein the at least one charge transport layer in contact with the photogenerating layer or in the upper most or top charge transport layer, contains a poly(imide-carbonate) polymer present in an amount of from about 1 to about 25 weight percent, from 2 to about 20 weight percent, from about 4 to about 10 weight percent, and more specifically about 10 weight percent, and a fluorinated polymer such as a PTFE present in an amount of for example, from about 1 to about 20 weight percent, from about 4 to about 15 weight percent, from about 6 to about 10 weight percent, and more specifically about 8 weight percent; a photoconductor comprised in sequence of a photogenerating layer comprised of a photogenerating pigment, and a hole transport layer, and wherein the transport layer is comprised of a hole transport component, a fluorinated polymer, such as a polytetrafluoroethylene (PTFE) and a poly(imide-carbonate) copolymer; a photoconductor comprising a supporting substrate, a ground plane layer, a hole blocking layer, a photogenerating layer comprised of at least one photogenerating pigment, and at least one charge transport layer comprised of at least one charge transport component, and where the charge transport layer has incorporated therein a poly(imide-carbonate) copolymer and a fluorinated polymer, and more specifically, where the fluorinated polymer is a PTFE obtainable, for example, as POLYFLON™ L-2 and L-5 available from Daikin Industries; a flexible photoconductive member comprised in sequence of a supporting substrate, a ground plane layer, a hole blocking or undercoat layer, a photogenerating layer thereover comprised of at least one photogenerating pigment, and as a second binder for the charge transport layer a poly(imide-carbonate) polymer, and as a lubricant for the charge transport layer a fluorinated polymer, such as PTFE; a photoconductor which includes a hole blocking layer and an adhesive layer where the adhesive layer is situated between the hole blocking layer and the photogenerating layer, and the hole blocking layer is situated between the supporting substrate layer, and the adhesive layer; a photoconductor comprising a supporting substrate, a hole blocking layer, a photogenerating layer, and two charge transport layers each comprised of at least one charge transport component, and wherein the first charge transport layer is in contact with the photogenerating layer, the second pass charge transport layer is in contact with the first charge transport layer, and the second top charge transport layer includes therein a poly(imide-carbonate) polymer and a fluoropolymer, such as PTFE; a photoconductor comprising a supporting substrate, a photogenerating layer in contact with the supporting substrate, and at least one charge transport layer in contact with the photogenerating layer, and wherein at least one, such as 1, 2, or 3 charge transport layers, contains a poly(imide-carbonate) polymer as illustrated herein, and a fluorinated polymer, such as PTFE; a photoconductor comprised in sequence of a photogenerating layer comprised of a photogenerating pigment, such as a hydroxygallium phthalocyanine, a chlorogallium phthalocyanine or a titanyl phthalocyanine, a charge transport layer thereover comprised of a charge transport component, a polycarbonate first resin binder, a polytetrafluoroethylene lubricant and as a second binder a poly(imide-carbonate) copolymer; a photoconductor wherein the fluorinated polymer particles contained in the charge transport layer possess a diameter of for example, from about 100 to about 1,000, from about 300 to about 875, from about 500 to about 700 nanometers measured by known light scattering processes; a photoconductor where the poly(imide-carbonate) polymer is of the following formulas/structures and with a weight average molecular weight of for example, of from about 30,000 to about 500,000, and a number average molecular weight of for example, from about 5,000 to about 100,000
wherein x and y each represents the mole percent of the repeating unit, x is from about 75 to about 95, and y is from about 5 to about 25; the fluorinated polymer present in the charge transport layer is polytetrafluoroethylene, and the charge transport layer is comprised of a hole transport component, the poly(imide-carbonate) polymer and the fluorinated polymer and further containing a third polymer of a polycarbonate, where the hole transport component is present in an amount of from about 25 to about 70 weight percent, or from about 35 to about 50 weight percent; the poly(imide-carbonate) polymer is present in an amount of from about 1 to about 20 weight percent, or from about 5 to about 15 weight percent, the fluorinated polymer is present in an amount of from about 1 to about 20 weight percent, or from about 4 to about 10 weight percent, and the third polymer polycarbonate is present in an amount of from about 20 to about 70 weight percent, or from about 30 to about 60 weight percent of the charge transport layer components, and more specifically where the hole transport component for the charge transport layer is N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, present in an amount of for example from about 35 to about 50 weight percent, a poly(imide-carbonate) for the charge transport layer is represented by
present in an amount of from about 5 to about 15 weight percent, the fluorinated polymerpresnet in the charge transport layer is PTFE, present in an amount of from about 5 to about 10 weight percent; and the third polymer polycarbonate present in the charge transport layer is polycarbonate Z, present in an amount of from about 35 to about 50 weight percent.
In an embodiment there is disclosed a photoconductor where the weight average molecular weight of the polycarbonate selected for the charge transport layer is for example, from about 20,000 to about 100,000 and the number average molecular weight of the polycarbonate for the charge transport layer is for example, from about 10,000 to about 50,000; the weight average molecular weight of the poly(imide-carbonate) is for example, from about 100,000 to about 300,000 and the number average molecular weight of the poly(imide-carbonate) is for example, from about 20,000 to about 70,000; the number average molecular weight of the fluorinated polymer is for example, from about 500,000 to about 2,000,000, and where the polycarbonate is polycarbonate Z; and in embodiments where the weight average molecular weight of the fluorinated polymer is for example, from about 500,000 to about 10,000,000; and the number average molecular weight of the fluorinated polymer is for example, from about 200,000 to about 5,000,
The photoconductors disclosed herein, in embodiments, include in the charge transport layer a poly(imide-carbonate) polymer as illustrated herein and as represented for example, by the following wherein x and y each represents the mole percent of the repeating unit as measured by known methods, and more specifically by NMR, and the sum of x+y is equal to about 100 and more specifically where x is from about 70 to about 98, from about 75 to about 95, or from about 80 to about 90 and y is from about 1 or about 2 to about 30, from about 5 to about 25, or from about 2 to about 15;
wherein R′ is hydrogen or alkyl with for example from 1 to about 12, from 1 to about 6 carbon atoms, like methyl; R is a suitable substituent that factors in the chemical bonding rules, such as for example, alkylene, with for example, from 1 to about 12, from 2 to about 8 carbon atoms, such as methylene; isopropylidene, cyclohexylidene, sulfonyl, ethylidene, hexafluoroisopropylidene and the like; Ar is a suitable substituent that factors in the chemical bonding rules, such as for example, arylylene; p-phenylene or m-phenylene; and Ar′ is a suitable substituent that factors in the chemical bonding rules, for example, Ar′ is benzene, diphenylbenzene, biphenyl, naphthalene, benzophenone, or perylene and the like.
Specific examples of the poly(imide-carbonate) copolymers present in the charge transport layer or charge transport layers can be represented by
wherein x and y each represents the mole percent of the repeating unit, and the sum of x+y is equal to about 100 and more specifically where x is from about 70 to about 98, or from about 80 to about 95, and y is from about 2 to 30, or from about 5 to about 20.
The poly(imide-carbonate) polymer possesses for example, a weight average molecular weight of from about 30,000 to about 500,000, or from about 100,000 to about 300,000; a number average molecular weight of for example, from about 5,000 to about 100,000, or from about 20,000 to about 70,000 as determined by known methods, such as GPC analysis.
The poly(imide-carbonate) polymer of the present disclosure can be prepared by modified known interfacial phosgenation processes, reference U.S. Pat. No. 4,393,190, the disclosure of which is totally incorporated herein by reference. Specifically, the poly(imide carbonate) polymer can be prepared by the following method. A mixture of a biphenol monomer, such as 4,4-cyclohexylidenebisphenol together with an aqueous inorganic base solution, such as sodium hydroxide, and an organic solvent, such as dichloromethane, in the presence of a suitable amount, such as about 0.5 to about 3 weight percent, of a phase transfer catalyst like benzyltriethylammonium chloride are stirred at room temperature (about 25° C.). To the mixture can then be added a triphosgene dichloromethane solution and a bis(imidephenol) monomer. A second catalyst, such as triethylamine, tributyl amine or the like (about 0.1 weight percent), can be added to accelerate the reaction. An about 10 percent excess of inorganic base solution may be selected to increase the molecular weight by about 20 percent at the end of a reaction. The interfacial phosgenation is generally accomplished at a temperature of from about 0 to about 100° C., and more specifically from room temperature (about 25° C.) to about 50° C. The reaction time is generally from for example, about 10 minutes to about 5 hours depending, for example, on the molecular weight of the polymer desired. The polymeric product obtained can then be purified by dissolving it in an organic solvent, such as dichloromethane or tetrahydrofuran (THF), and then precipitating in methanol to provide a pure, for example from 90 to 99.5 percent pure, polymer which are suitable as charge transport layer binders, and which polymer and its structure can be confirmed by known methods, such as NMR.
Illustrative examples of bisphenol monomers selected for the preparation of the poly(imide-carbonate)s include for example, bisphenol, bis(hydroxyphenyl)methane, bis(hydroxyphenyl)dimethylmethane, bis(hydroxyphenyl)cyclohexane, and the like, present in an amount of for example, from about 70 to about 98 weight percent, or from about 80 to about 95 weight percent.
Illustrative examples of bis(imidephenol) monomers selected for the preparation of the poly(imide-carbonate) can be represented by
and the like, present in an amount of for example, from about 2 to about 30 weight percent, or from about 5 to about 20 weight percent.
Examples of the fluorinated polymer included in the charge transport layer are polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and hexafluoropropylene, a copolymer of tetrafluoroethylene and perfluoro(propyl vinyl ether), a copolymer of tetrafluoroethylene and perfluoro(ethyl vinyl ether), a copolymer of tetrafluoroethylene and perfluoro(methyl vinyl ether), and a copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride, mixtures thereof, and the like, inclusive of a number of suitable known fluorinated polymers, each of the fluorinated polymers or polymer being present in an amount of for example from about 1 to about 20 weight percent, from about 2 to about 18 weight percent, or from about 4 to about 10 weight percent.
In embodiments, the fluorinated polymers are nanosized/micronsized particles with a diameter of, for example, from about 200 nanometers to about 10 microns, or from about 400 nanometers to about 3 microns. Specific fluorinated polymer examples are PTFE POLYFLON™ L-2 (average particle diameter size of about 3 microns), L-5 (average particle diameter size of about 5 microns), L-5F (average particle size of about 4 microns), LDW-410 (average particle size diameter of about 0.2 micron), all commercially available from Daikin Industries, Ltd., Japan; and PTFE NANOFLON® P51A (average particle size about 0.3 micron), all commercially available from Shamrock Technologies, NJ, USA.
The polycarbonate resin binder included in the charge transport layer possesses, for example, a number average molecular weight (Mn) of from about 10,000 to about 80,000, or from about 20,000 to about 60,000, and a weight average molecular weight (Mw) of from about 20,000 to about 100,000, or from about 40,000 to about 80,000, where Mw and Mn were determined by Gel Permeation Chromatography (GPC). Specific examples of the polycarbonate resin, a number of which are prepared from di(hydroxyphenyl)alkanes, such as 2,2-di(4-hydroxyphenyl)propane are illustrated in U.S. Pat. No. 5,030,707, the disclosure of which is totally incorporated herein by reference in its entirety and include PCZ-400 [poly(4,4′-dihydroxy-diphenyl-1-1-cyclohexane carbonate), Mw=40,000] available from Mitsubishi Gas Chemical Company, Ltd.; poly(4,4′-isopropylidene-diphenylene carbonate) (also referred to as bisphenol-A-polycarbonate), poly(4,4′-cyclohexylidine diphenylene carbonate) (also referred to as bisphenol-Z-polycarbonate), poly(4,4′-isopropylidene-3,3′-dimethyl-diphenyl carbonate (also referred to as bisphenol-C-polycarbonate), and the like and mixtures thereof, present for example, in an amount of from about 25 to about 60 weight percent, from about 30 to about 50 weight percent, or from about 35 to about 45 weight percent.
A number of known components can be selected for the various photoconductor layers, such as the supporting substrate, the photogenerating layer, the charge transport layer, the hole blocking layer when present, and the adhesive layer when present, such as those components as illustrated in the copending applications referenced herein.
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 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 including known or future developed materials. 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, gold, 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 microns, or of a minimum thickness of less than about 50 microns 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®.
Examples of electrically conductive layers or ground plane layers usually present on nonconductive substrates are gold, gold containing compounds, aluminum, titanium, titanium/zirconium, and other known suitable components. The thickness of the metallic ground plane is, for example, from about 10 to about 100 nanometers, from about 20 to about 50 nanometers, and more specifically, about 35 nanometers, and the titanium or titanium/zirconium ground plane is, for example, from about 10 to about 30 nanometers, and more specifically, about 20 nanometers in thickness.
An optional hole blocking layer, when present, is usually in contact with the ground plane, and can be comprised of a number of known components as illustrated herein, such as metal oxides, phenolic resins, aminosilanes, mixtures thereof, and the like.
Aminosilane examples included in the hole blocking layer can be represented by
wherein R1 is an alkylene group containing, for example, from 1 to about 25 carbon atoms; R2 and R3 are independently selected from the group consisting of at least one of hydrogen or alkyl containing, for example, from 1 to about 12 carbon atoms, and more specifically, from 1 to about 4 carbon atoms; aryl with, for example, from about 6 to about 42 carbon atoms, such as a phenyl group; and a poly(alkylene like ethylene amino) group; and R4, R5 and R6 are independently selected from an alkyl group containing, for example, from 1 to about 10 carbon atoms, and more specifically, from 1 to about 4 carbon atoms.
Aminosilane specific examples include 3-aminopropyl triethoxysilane, N,N-dimethyl-3-aminopropyl triethoxysilane, N-phenylaminopropyl trimethoxysilane, triethoxysilylpropylethylene diamine, trimethoxysilylpropylethylene diamine, trimethoxysilylpropyldiethylene triamine, N-aminoethyl-3-aminopropyl trimethoxysilane, N-2-aminoethyl-3-aminopropyl trimethoxysilane, N-2-aminoethyl-3-aminopropyl tris(ethylethoxy)silane, p-aminophenyl trimethoxysilane, N,N′-dimethyl-3-aminopropyl triethoxysilane, 3-aminopropylmethyl diethoxysilane, 3-aminopropyl trimethoxysilane, N-methylaminopropyl triethoxysilane, methyl[2-(3-trimethoxysilylpropylamino)ethylamino]-3-proprionate, (N,N′-dimethyl 3-amino)propyl triethoxysilane, N,N-dimethylaminophenyl triethoxysilane, trimethoxysilyl propyldiethylene triamine, and the like, and mixtures thereof. Yet more specific aminosilane materials are 3-aminopropyl triethoxysilane (γ-APS), N-aminoethyl-3-aminopropyl trimethoxysilane, (N,N′-dimethyl-3-amino)propyl triethoxysilane, and mixtures thereof.
The aminosilane may be hydrolyzed to form a hydrolyzed silane solution before being added into the final undercoat coating solution or dispersion. During hydrolysis of the aminosilanes, the hydrolyzable groups, such as alkoxy groups, are replaced with hydroxyl groups. The pH of the hydrolyzed silane solution can be controlled to obtain excellent characteristics on curing, and to result in electrical stability. A solution pH of, for example, from about 4 to about 10 can be selected, and more specifically, a pH of from about 7 to about 8. Control of the pH of the hydrolyzed silane solution may be affected with any suitable material, such as generally organic or inorganic acids. Typical organic and inorganic acids include acetic acid, citric acid, formic acid, hydrogen iodide, phosphoric acid, hydrofluorosilicic acid, p-toluene sulfonic acid, and the like.
The hole blocking layer can, in embodiments, be prepared by a number of known methods, the process parameters being dependent, for example, on the photoconductor member desired. The hole blocking layer can be coated as a solution or a dispersion onto the supporting substrate or on to the ground plane layer by the use of a spray coater, dip coater, extrusion coater, roller coater, wire-bar coater, slot coater, doctor blade coater, gravure coater, and the like, and dried at from about 40 to about 200° C. for a suitable period of time, such as from about 1 minute to about 10 hours, under stationary conditions or in an air flow. The coating can be accomplished to provide a final coating thickness of, for example, from about 0.01 to about 30 microns, or from about 0.02 to about 5 microns, or from about 0.03 to about 0.5 micron after drying.
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, chlorogallium phthalocyanine Type C, 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 to about 10 microns, and more specifically, from about 0.25 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 to about 95 percent by volume of the photogenerating pigment is dispersed in about 95 to about 5 percent by volume of the resinous binder, or from about 20 to about 30 percent by volume of the photogenerating pigment is dispersed in about 70 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, polyvinyl 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 layer 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 polymeric binder materials that can be selected as the matrix or binder for the photogenerating layer 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, acrylonitrile copolymers, poly(vinyl chloride), vinyl chloride and vinyl acetate copolymers, acrylate copolymers, alkyd resins, cellulosic film formers, poly(amideimide), styrene butadiene 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 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 10 microns, or from about 0.2 to about 2 microns can be applied to or deposited on a supporting substrate, or 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 supporting substrate surface prior to the application of a photogenerating layer. When desired, an adhesive layer may be included between the charge blocking, hole blocking layer or interfacial layer, and the photogenerating layer. Usually, the photogenerating layer is applied onto the blocking layer, and a charge transport layer or plurality of charge transport layers is 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 to about 0.3 micron. 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, polyvinyl butyral), polyvinyl alcohol), polyurethane, and polyacrylonitrile. This layer is, for example, of a thickness of from about 0.001 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.
A number of charge transport compounds can be included in the charge transport layer, which layer generally is of a thickness of from about 5 to about 75 microns, and more specifically, of a thickness of from about 10 to about 40 microns. Examples of charge transport components are represented by the following formulas/structures
wherein X is a suitable hydrocarbon like alkyl, alkoxy, aryl, and derivatives thereof; a halogen, or mixtures thereof, and especially those substituents selected from the group consisting of Cl and CH3; and molecules of the following formulas
wherein X, Y and Z are independently alkyl, alkoxy, aryl, a halogen, or mixtures thereof, and wherein at least one of Y and Z are present.
Alkyl and alkoxy contain, for example, from 1 to about 25 carbon atoms, and more specifically, from 1 to about 12 or from 1 to about 6 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, and the corresponding alkoxides. Aryl can contain from 6 to about 36, from 6 to about 24, from 6 to about 18, from 6 to 12 carbon atoms, such as phenyl, and the like. Halogen includes chloride, bromide, iodide, and fluoride. Substituted alkyls, alkoxys, and aryls can also be selected in embodiments.
Examples of specific aryl amines that can be selected for the charge transport layer include N,N′-diphenyl-N,N′-bis(alkylphenyl)-1,1-biphenyl-4,4′-diamine wherein alkyl is selected from the group consisting of methyl, ethyl, propyl, butyl, hexyl, and the like; N,N-diphenyl-N,N′-bis(halophenyl)-1,1-biphenyl-4,4′-diamine wherein the halo substituent is a chloro substituent; 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, and the like. Other known charge transport layer molecules can be selected, reference for example, U.S. Pat. Nos. 4,921,773 and 4,464,450, the disclosures of which are totally incorporated herein by reference.
Examples of optional third binder to for example permit enhanced miscibility with the hole transport component and to reduce cost in addition to the poly(imide-carbonate) polymer and the PTFE selected for the charge transport layers include polycarbonates, polyarylates, acrylate polymers, vinyl polymers, cellulose polymers, polyesters, polysiloxanes, polyamides, polyurethanes, poly(cyclo olefins), epoxies, and random or alternating copolymers thereof; and more specifically, polycarbonates such as poly(4,4′-isopropylidene-diphenylene) carbonate (also referred to as bisphenol-A-polycarbonate), poly(4,4′-cyclohexylidine diphenylene) carbonate (also referred to as bisphenol-Z-polycarbonate), poly(4,4′-isopropylidene-3,3′-dimethyl-diphenyl) carbonate (also referred to as bisphenol-C-polycarbonate), and the like. In embodiments, electrically inactive third resin binders are comprised of polycarbonate resins with a molecular weight of from about 20,000 to about 100,000, or with a molecular weight Mw of from about 50,000 to about 100,000. Generally, the transport layer contains from about 10 to about 75 percent by weight of the charge transport material, and more specifically, from about 35 to about 50 percent of this material.
The charge transport layer or layers, and more specifically, a first charge transport in contact with the photogenerating layer, and thereover a top or second charge transport overcoating layer, may comprise charge transporting small molecules dissolved or molecularly dispersed in a film forming electrically inert polymer such as a polycarbonate. In embodiments, “dissolved” refers, for example, to forming a solution in which the small molecule is dissolved in the polymer to form a homogeneous phase; and “molecularly dispersed in embodiments” refers, for example, to charge transporting molecules dispersed in the polymer, the small molecules being dispersed in the polymer on a molecular scale. Various charge transporting or electrically active small molecules may be selected for the charge transport layer or layers. In embodiments, charge transport refers, for example, to charge transporting molecules as a monomer that allows the free charge generated in the photogenerating layer to be transported across the transport layer.
Examples of hole transporting molecules present in the charge transport layer in contact with the photogenerating layer that contains a photogenerating pigment and a polymeric binder, in an amount of from about 50 to about 75 weight percent, include, for example, pyrazolines such as 1-phenyl-3-(4′-diethylamino styryl)-5-(4″-diethylamino phenyl)pyrazoline; aryl amines such as N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine, 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; hydrazones such as N-phenyl-N-methyl-3-(9-ethyl)carbazyl hydrazone and 4-diethylamino benzaldehyde-1,2-diphenyl hydrazone; and oxadiazoles such as 2,5-bis(4-N,N′-diethylaminophenyl)-1,2,4-oxadiazole, stilbenes, and the like. However, in embodiments, to minimize or avoid cycle-up in equipment, such as printers, with high throughput, the charge transport layer should be substantially free (less than about two percent) of di or triamino-triphenyl methane. A small molecule charge transporting compound that permits injection of holes into the photogenerating layer with excellent efficiency, and transports them across the charge transport layer with short transit times includes 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, and N,N′-diphenyl-N,N′-bis(3-chlorophenyl)-[p-terphenyl]-4,4″-diamine, or mixtures thereof. If desired, the charge transport material in the charge transport layer may comprise a polymeric charge transport material, or a combination of a small molecule charge transport material and a polymeric charge transport material.
Examples of components or materials optionally incorporated into the charge transport layers, at least one, or one charge transport layer to, for example, enable excellent lateral charge migration (LCM) resistance include hindered phenolic antioxidants, such as tetrakis methylene(3,5-di-tert-butyl-4-hydroxy hydrocinnamate)methane (IRGANOX™ 1010, available from Ciba Specialty Chemical), butylated hydroxytoluene (BHT), and other hindered phenolic antioxidants including SUMILIZER™ BHT-R, MDP-S, BBM-S, WX-R, NR, BP-76, BP-101, GA-80, GM and GS (available from Sumitomo Chemical Co., Ltd.), IRGANOX™ 1035, 1076, 1098, 1135, 1141, 1222, 1330, 1425WL, 1520L, 245, 259, 3114, 3790, 5057 and 565 (available from Ciba Specialties Chemicals), and ADEKA STAB™ AO-20, AO-30, AO-40, AO-50, AO-60, AO-70, AO-80 and AO-330 (available from Asahi Denka Co., Ltd.); hindered amine antioxidants such as SANOL™ LS-2626, LS-765, LS-770 and LS-744 (available from SNKYO CO., Ltd.), TINUVIN™ 144 and 622LD (available from Ciba Specialties Chemicals), MARK™ LA57, LA67, LA62, LA68 and LA63 (available from Asahi Denka Co., Ltd.), and SUMILIZER™ TPS (available from Sumitomo Chemical Co., Ltd.); thioether antioxidants such as SUMILIZER™ TP-D (available from Sumitomo Chemical Co., Ltd); phosphite antioxidants such as MARK™ 2112, PEP-8, PEP-24G, PEP-36, 329K and HP-10 (available from Asahi Denka Co., Ltd.); other molecules such as bis(4-diethylamino-2-methylphenyl)phenylmethane (BDETPM), bis-[2-methyl-4-(N-2-hydroxyethyl-N-ethyl-aminophenyl)]-phenylmethane (DHTPM), and the like. The weight percent of the antioxidant in at least one of the charge transport layers is from about 0 to about 20 weight percent, from about 1 to about 10 weight percent, or from about 3 to about 8 weight percent.
A number of processes may be used to mix, and thereafter apply the charge transport layer or layers coating mixture to the photogenerating layer. Typical application techniques include spraying, dip coating, roll coating, wire wound rod coating, and the like. Drying of the charge transport deposited coating may be effected by any suitable conventional technique such as oven drying, infrared radiation drying, air drying, and the like.
The thickness of each of the charge transport layers, in embodiments, is from about 10 to about 70 microns, or from about 20 to about 50 microns, however thicknesses outside this range may, in embodiments, also be selected. The charge transport layer should be an insulator to the extent that an electrostatic charge placed on the hole transport layer is not conducted in the absence of illumination at a rate sufficient to prevent formation and retention of an electrostatic latent image thereon. In general, the ratio of the thickness of the charge transport layer to the photogenerating layer can be from about 2:1 to 200:1, and in some instances 400:1. The charge transport layer is substantially nonabsorbing to visible light or radiation in the region of intended use, but is electrically “active” in that it allows the injection of photogenerated holes from the photoconductive layer, or photogenerating layer, and allows these holes to be transported to selectively discharge a surface charge present on the surface of the photoconductor. Typical application techniques for the charge transport layer include spraying, dip coating, roll coating, wire wound rod coating, and the like. Drying of the deposited charge transport coating may be effected by any suitable conventional technique, such as oven drying, infrared radiation drying, air drying, and the like. A known optional overcoating may be applied over the charge transport layer to provide for further photoconductor abrasion protection.
In embodiments, the present disclosure relates to a photoconductive imaging member comprised of a titanium/zirconium containing ground plane layer, a hole blocking layer, a photogenerating layer, a poly(imide-carbonate) and PTFE polymer containing charge transport layer, and an optional overcoating charge transport layer; a photoconductive member with a photogenerating layer of a thickness of from about 0.1 to about 8 microns, and at least one transport layer each of a thickness of from about 5 to about 100 microns; an imaging method and an 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, a ground plane layer, a hole blocking layer, and thereover a photogenerating layer comprised of a photogenerating pigment, and a charge transport layer and thereover an overcoating charge transport layer, and where the transport layer is of a thickness of from about 40 to about 70 microns; a photoconductor wherein the photogenerating layer contains a photogenerating pigment present in an amount of from about 8 to about 95 weight percent; a photoconductor wherein the thickness of the photogenerating layer is from about 0.1 to about 4 microns; a photoconductive member wherein the photogenerating layer contains 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 all layer components is about 100 percent; a member wherein the photogenerating component is a titanyl phthalocyanine, a chlorohydroxy gallium phthlaocyanine Type C, or a hydroxygallium 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 or photoconductor wherein the conductive substrate is aluminum, aluminized polyethylene terephthalate, aluminized polyethylene naphthalate, titanized polyethylene terephthalate, titanized polyethylene naphthalate, titanized/zirconized polyethylene terephthalate, titanized/zirconized polyethylene naphthalate, goldized polyethylene terephthalate, or a goldized polyethylene naphthalate; a xerographic imaging member wherein the photogenerating resinous binder is selected from the group consisting of 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 containing in the photogenerating layer for example, a hydroxygallium phthalocyanine, or a chlorogallium phthalocyaine and wherein each and more specifically a first or a first and second charge transport layer comprises
wherein X is selected from the group consisting of alkyl, alkoxy, and halogen; an imaging member wherein alkyl and alkoxy contains from about 1 to about 12 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 comprises
wherein X and Y are independently alkyl, alkoxy, aryl, a halogen, or mixtures thereof; an imaging member wherein alkyl and alkoxy for the charge transport component aryl amine contain from about 1 to about 12 carbon atoms; an imaging member wherein alkyl contains from about 1 to about 5 carbon atoms; an imaging member wherein the photogenerating pigment present in the photogenerating layer is comprised of chlorogallium phthalocyanine Type C, 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 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 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 which comprises generating an electrostatic latent image on an imaging member developing the latent image, and transferring the developed electrostatic image to a suitable substrate; a method of imaging wherein the imaging member is exposed to light of a wavelength of from about 370 to about 950 nanometers; a photoconductive 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; a member wherein the photogenerating layer is of a thickness of from about 0.1 to about 50 microns; a member wherein the photogenerating pigment is dispersed in from about 1 weight percent to about 80 weight percent of 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; an imaging member wherein the photogenerating component is Type V hydroxygallium phthalocyanine, Type V titanyl phthalocyanine or chlorogallium phthalocyanine, 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; an imaging member wherein the photogenerating layer contains a metal free phthalocyanine; a photoconductor wherein the photogenerating layer contains an alkoxygallium phthalocyanine; photoconductive imaging members comprised of a supporting substrate, a photogenerating layer, a hole transport layer, and in embodiments wherein a plurality of charge transport layers are selected, such as for example, from two to about ten, and more specifically two, 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 charge transport component can be represented by the following formulas/structures
The following Examples are being submitted to illustrate embodiments of the present disclosure. Molecular weights were determined by Gel Permeation analysis. The ratios recited were determined primarily by the amount of components selected for the preparations indicated.
The poly(imide-carbonate) polymer of the following structure (x=95 mole percent, y=5 mole percent) was synthesized as follows:
To a 5-liter round-bottomed flask was charged a mixture of 218.12 grams of 1,2,4,5-benzenetetracarboxylic dianhydride, 240.09 grams of 3-aminophenol and 2.5 liters of acetic acid, and the resulting mixture was stirred at 110° C. for 6 hours. After the reaction mixture was cooled down to room temperature (25° C.), the resulting yellowish solid was collected by filtration and then stirred in 2.5 liters of methanol at room temperature (25° C.). After filtration, the solid material obtained was collected by filtration, and then recrystallized from dimethylformaldehyde to provide, after drying in a vacuum oven for 48 hours at 150° C., 384 grams of bis(imidephenol) (95.9% isolated yield, (structure confirmed by NMR) of
A mixture of 2.002 grams of bis(imidephenol) as obtained above, 0.228 grams of benzyltriethylammonium chloride, 200 grams of a 0.4% aqueous sodium hydroxide solution, 0.30 gram of tributylamine and 85 milliliters of dichloromethane were mechanically stirred in a 2-liter flask equipped with a mechanical stir. A mixture of 21.63 grams of 4,4-cyclohexylbisphenol bischloroformate in 85 milliliters of methylene chloride was added slowly to the mixture. After the mixture obtained was stirred using a magnetic stirring bar at room temperature, about 25 degrees Centigrade for 10 minutes, a slurry containing 10.73 grams of 4,4-cyclohexylbisphenol in 200 grams of 1.5% sodium hydroxide solution was added, and the pH of the reaction mixture (measured by a pH meter) was maintained at about 12 with additional sodium hydroxide solution as needed. After being stirred for 4 hours, the reaction mixture was diluted with 300 milliliters of methylene chloride and transferred to a 2-liter separatory funnel and allowed to sit or remain situated on a laboratory bench to phase separate overnight, about 23 hours. The resulting organic layer was then separated and added dropwise into 3 liters of stirring methanol. The precipitated polymer was collected by filtration and dried in vacuum oven at 60° C. overnight, about 23 hours. The polymer product was then dissolved in 700 milliliters of methylene chloride, and again precipitated from 3 liters of methanol. The precipitated polymer product was washed with 2.5 liters of methanol, and dried in vacuum oven at 60° C. overnight to provide 26 grams of the above poly(imide-carbonate) (86% isolated yield, the structure being confirmed by NMR) and with a weight average molecular weight (Mw) of the poly(imide-carbonate) of 158,000 as measured by GPC using polystyrene as standard.
The poly(imide-carbonate) polymer of the following structure (x=75 mole percent, y=25 mole percent) was synthesized as follows:
A mixture of 1.121 gram of bis(imidephenol) of
0.0228 gram of benzyltriethylammonium chloride, 22 grams of a 2% aqueous sodium hydroxide solution, 0.01 gram of tributylamine and 30 milliliters of dichloromethane were mechanically stirred in a 500-milliliter flask equipped with a mechanical stir. A solution of 2.16 grams of 4,4-cyclohexylbisphenol bischloroformate in 30 milliliters of methylene chloride was added slowly to the mixture. After the mixture is stirred at room temperature for 10 minutes, a slurry containing 0.54 grams of 4,4-cyclohexylbisphenol in 10 grams of a 1.5% sodium hydroxide solution was added, and the pH of the reaction mixture was retained at about 12 with additional sodium hydroxide solution added as needed. After being stirred for 4 hours, the reaction mixture was diluted with 60 milliliters of methylene chloride and then transferred to a 500-milliliter separatory funnel and let to phase separate overnight. The organic layer was separated and added dropwise to 1 liter of stirring methanol. The precipitated polymer was collected by filtration and dried in vacuum oven at 60° C. overnight. The polymer obtained was dissolved in 120 milliliters of methylene chloride and again precipitated from 1 liter of methanol. The precipitated polymer was washed with 1 liter of methanol, and dried in vacuum oven at 60° C. overnight to provide 2.6 grams of the poly(imide-carbonate) (73.4% isolated yield, structure confirmed by NMR). The weight average molecular weight (Mw) of the poly(imide-carbonate) product was 100,000 z measured by GPC using polystyrene as standard.
On a 30 millimeter thick aluminum drum substrate, an undercoat layer was prepared and deposited thereon as follows.
Zirconium acetylacetonate tributoxide (35.5 parts), γ-aminopropyl triethoxysilane (4.8 parts), and poly(vinyl butyral) BM-S (2.5 parts) were dissolved in n-butanol (52.2 parts). The resulting solution was then coated by a dip coater on the above aluminum drum substrate, and the coating solution layer was pre-heated at 59° C. for 13 minutes, humidified at 58° C. (dew point=54° C.) for 17 minutes, and dried at 135° C. for 8 minutes. The thickness of the resulting undercoat layer was approximately 1.3 microns.
A photogenerating layer, 0.2 micron in thickness, comprising chlorogallium phthalocyanine (Type C) was deposited on the above undercoat layer. The photogenerating layer coating dispersion was prepared as follows. 2.7 Grams of chlorogallium phthalocyanine (ClGaPc) Type C pigment was mixed with 2.3 grams of the polymeric binder (carboxyl-modified vinyl copolymer, VMCH, available from Dow Chemical Company), 15 grams of n-butyl acetate, and 30 grams of xylene. The resulting mixture was mixed in an Attritor mill with about 200 grams of 1 millimeter Hi-Bea borosilicate glass beads for about 3 hours. The dispersion mixture obtained was then filtered through a 20 micron Nylon cloth filter, and the solids content of the dispersion was diluted to about 6 weight percent.
Subsequently, a 34 micron charge transport layer was coated on top of the above photogenerating layer from a solution prepared by dissolving N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (mTBD, 4 grams), and a film forming polymer binder PCZ-400 [poly(4,4′-dihydroxy-diphenyl-1-1-cyclohexane carbonate), Mw=40,000] available from Mitsubishi Gas Chemical Company, Ltd. (6 grams) in a solvent mixture of 21 grams of tetrahydrofuran (THF), and 9 grams of toluene, followed by drying in an oven at about 120° C. for about 40 minutes. The resulting charge transport layer PCZ-400/mTBD ratio was 60/40.
A photoconductor was prepared by repeating the process of Comparative Example 1 except that the 34 micron thick charge transport layer was coated on top of the photogenerating layer from a dispersion prepared from N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4″-diamine (4 grams), a film forming polymer binder PCZ-400 [poly(4,4′-dihydroxy-diphenyl-1-1-cyclohexane carbonate), Mw=40,000], available from Mitsubishi Gas Chemical Company, Ltd. (6 grams), and polytetrafluoroethylene, PTFE POLYFLON™ L-2 microparticle, available from Daikin Industries, (1 gram) dissolved/dispersed in a solvent mixture of 21 grams of tetrahydrofuran (THF) and 9 grams of toluene via a CAVIPRO™ 300 nanomizer (Five Star Technology, Cleveland, Ohio) followed by drying in an oven at about 120° C. for about 40 minutes. The charge transport layer PCZ-400/charge transport component/PTFE L-2 ratio was 54.5/36.4/9.1.
A photoconductor was prepared by repeating the process of Comparative Example 1 except that the 34 micron thick charge transport layer was coated on top of the photogenerating layer from a dispersion prepared from N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (4 grams or 9.7 weight percent), the film forming polymer binder PCZ-400 [poly(4,4′-dihydroxy-diphenyl-1-1-cyclohexane carbonate), Mw=40,000], available from Mitsubishi Gas Chemical Company, Ltd. (5 grams, or 12.2 weight percent), the poly(imide carbonate) copolymer of Synthetic Example I (1 gram, 2.4 weight percent), and polytetrafluoroethylene, PTFE POLYFLON™ L-2 microparticle, available from Daikin Industries (1 gram, or 2.4 weight percent), dissolved/dispersed in a solvent mixture of 21 grams or 51.2 weight percent of tetrahydrofuran (THF) and 9 grams or 22.1 weight percent of toluene. The charge transport layer PCZ-400/poly(imide carbonate)/mTBD/PTFE L-2 ratio was about 45.4/9.1/36.4/9.1 based on the above initial feed amounts.
A photoconductor is prepared by repeating the process of Example I except that the 34 micron thick charge transport layer is coated on top of the photogenerating layer from a dispersion prepared from N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (4 grams, or 9.7 weight percent), the polymer binder PCZ-400 [poly(4,4′-dihydroxy-diphenyl-1-1-cyclohexane carbonate), Mw=40,000], available from Mitsubishi Gas Chemical Company, Ltd. (5 grams, or 12.2 weight percent), the poly(imide carbonate) copolymer of Synthetic Example II (1 gram, 2.4 weight percent), and polytetrafluoroethylene, PTFE POLYFLON™ L-2 microparticle, available from Daikin Industries (1 gram, 2.4 weight percent), dissolved/dispersed in a solvent mixture of 21 grams or 51.2 weight percent of tetrahydrofuran (THF) and 9 grams or 22.1 weight percent of toluene. The charge transport layer PCZ-400/poly(imide carbonate)/mTBD/PTFE L-2 ratio is about 45.4/9.1/36.4/9.1.
The above prepared photoconductors of Comparative Example 2 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 were 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 above photoconductors were tested at surface potentials of 700 volts with the exposure light intensity incrementally increased by means of regulating a series of neutral density filters; and 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.).
Substantially similar PIDCs were obtained for the above two photoconductors. Therefore, the incorporation of the above poly(imide-carbonate) copolymer and PTFE into the charge transport layer did not adversely affect the electrical properties of these photoconductors.
Wear tests of the photoconductors of Comparative Examples 1 and 2 and Example I were performed using an in house wear test fixture (biased charging roll, and BCR charging with peak to peak voltage of 1.45 kilovolts). The total thickness of each photoconductor was measured via Permascope before each wear test was initiated. Then the photoconductors were separately placed into the wear fixture for 50 kilocycles. The total photoconductor thickness was measured again with the Permascope, and the difference in thickness was used to calculate wear rate (nanometers/kilocycle) of the photoconductors. The smaller the wear rate, the more wear resistant was the photoconductor. The wear rate data is summarized in Table 1.
When PTFE was incorporated into the charge transport layer, the wear rate was reduced from about 58 nanometers/kilocycle (Comparative Example 1) to about 30 nanometers/kilocycle (Comparative Example 2). When the disclosed poly(imide-carbonate) was further incorporated into the PTFE containing charge transport layer, the wear rate was further reduced from about 30 nanometers/kilocycle (Comparative Example 2) to about 17 nanometers/kilocycle (Example I). A combination of the disclosed poly(imide-carbonate) and PTFE in the charge transport layer reduced the wear rate from about 58 nanometers/kilocycle (Comparative Example 1) to about 17 nanometers/kilocycle (Example I), about a 70% wear reduction.
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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