Patent Application
20110318680
This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered flexible, belt imaging members, and rigid drum photoconductors comprised of an optional supporting medium like a substrate, a mixture of a hydroxygallium phthalocyanine, and a hydroxyaluminum phthalocyanine containing photogenerating layer, and a charge transport layer, 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, and wherein at least one of the charge transport layers contains at least one charge transport component, a polymer or resin binder, and an optional antioxidant.
The photoconductors illustrated herein, in embodiments, have excellent electricals, more rapid PIDCs of, for example, from about 20 to about 50 volts lower V(1 erg/cm2) as compared to a similar photoconductor that is free of the silanol in the photogenerating layer.
In embodiments, the photoconductors illustrated herein are believed to possess extended lifetimes; low Vr (residual potential), and allow the substantial prevention of Vr cycle up when appropriate, high sensitivity; low acceptable image ghosting characteristics, low background and/or minimal charge deficient spots (CDS), and desirable toner cleanability as compared to photoconductors with hydroxygallium phthalocyanine photogenerating layers that do not contain a silanol. At least one, in embodiments, refers, for example, to one, to from 1 to about 10, to from 2 to about 7; to from 2 to about 4, to two, to one, and the like.
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 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.
Illustrated in U.S. Pat. No. 7,560,206, the disclosure of which is totally incorporated herein by reference, is a photoconductor comprising an optional substrate, a photogenerating layer comprised of a photogenerating component and a silanol, and at least one charge transport layer comprised of at least one charge transport component, and wherein the silanol is selected from the group comprised of the following formulas/structures
and wherein R and R′ are independently alkyl, alkoxy, aryl, and substituted derivatives thereof, and mixtures thereof.
Illustrated in U.S. Pat. No. 7,541,122, the disclosure of which is totally incorporated herein by reference, is 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 at least one silanol.
In U.S. Pat. No. 7,670,733, 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 comprised of at least one charge transport component, and wherein the photogenerating layer contains a Type V hydroxygallium phthalocyanine having incorporated therein a silanol.
There is illustrated in U.S. Pat. No. 5,473,064, the disclosure of which is totally incorporated herein by reference, a process for the preparation of hydroxygallium phthalocyanine which comprises the hydrolysis of a halogallium phthalocyanine precursor, like Type I chlorogallium phthalocyanine, to a hydroxygallium phthalocyanine like Type I, and conversion of the resulting hydroxygallium phthalocyanine to Type V hydroxygallium phthalocyanine by contacting the resulting hydroxygallium phthalocyanine with an organic solvent; and wherein the precursor halogallium phthalocyanine is obtained by the reaction of gallium halide with diiminoisoindolene in an organic solvent. More specifically, 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, whereby a pigment precursor Type I chlorogallium phthalocyanine is prepared by reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, present in an amount of from about 10 to about 100 parts, and preferably about 19 parts with 1,3-diiminoisoindolene (DI3) in an amount of from about 1 to about 10 parts, and preferably about 4 parts of DI3, 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 to about 50 volume parts, and preferably 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 preferably about 24 hours.
There is illustrated in U.S. Pat. No. 5,482,811, the disclosure of which is totally incorporated herein by reference, a process for the preparation of hydroxygallium phthalocyanines which comprises hydrolyzing a gallium phthalocyanine precursor pigment by dissolving said 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.
There is illustrated in U.S. Pat. No. 5,521,306, the disclosure of which is totally incorporated herein by reference, a process for the preparation of Type V hydroxygallium phthalocyanine which comprises the in situ formation of an alkoxy-bridged gallium phthalocyanine dimer, hydrolyzing the alkoxy-bridged gallium phthalocyanine dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product obtained to Type V hydroxygallium phthalocyanine.
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.
In U.S. Pat. No. 4,921,769, the disclosure of which is totally incorporated herein by reference, there are illustrated photoconductive imaging members with blocking layers of certain polyurethanes.
The appropriate components and processes of the above recited patents may be selected for the present disclosure in embodiments thereof.
Disclosed are photoconductors with many of the advantages illustrated herein, such as improved electricals, for example, rapid PIDCs; extended lifetimes of service of, for example, in excess of about 1,000,000 xerographic imaging cycles; excellent electronic characteristics; stable electrical properties; excellent image ghosting properties; minimal background and/or minimal charge deficient spots (CDS); resistance to charge transport layer cracking upon exposure to the vapor of certain solvents; excellent surface characteristics; excellent wear resistance; compatibility with a number of toner compositions; the avoidance of or minimal imaging member scratching characteristics; consistent Vr (residual potential) that is substantially flat or no change over a number of imaging cycles as illustrated by the generation of known PIDC (Photo-Induced Discharge Curve), and the like.
Also disclosed are layered photoconductive members, which are responsive to near infrared radiation of from about 700 to about 900 nanometers.
Further disclosed are layered photoresponsive imaging members with sensitivity to visible light.
Additionally disclosed are 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 a photoconductor comprising an optional supporting substrate, a photogenerating layer, and a transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a mixture of a hydroxygallium phthalocyanine, a hydroxyaluminum phthalocyanine, and a silanol; a photoconductor comprising a supporting substrate, a photogenerating layer, and a charge transport layer, and wherein the photogenerating layer contains a mixture of a hydroxygallium phthalocyanine, a hydroxyaluminum phthalocyanine, a polymer binder, and a silanol selected from the group comprised of at least one of the silanols represented by the following formulas/structures
and wherein R and R′ are independently selected from the group consisting of alkyl, alkoxy, aryl, and substituted derivatives thereof, and mixtures thereof; a photoconductor comprised in sequence of a substrate, a photogenerating layer, and a charge transport layer, and wherein the photogenerating layer is comprised of a mixture of hydroxygallium phthalocyanine Type V, hydroxyaluminum phthalocyanine, a polycarbonate binder, and a silanol, and wherein the silanol is selected from the group consisting of at least one of
wherein R is independently alkyl, alkoxy, or aryl; and wherein the silanol is present, for example, in an amount of from about 1 to about 10 weight percent; a photoconductor comprised in sequence of a substrate, a hole blocking layer, an adhesive layer, photogenerating layer, and a charge transport layer, and wherein the photogenerating layer is comprised of a hydroxygallium phthalocyanine, a hydroxyaluminum phthalocyanine, a polycarbonate binder and a silanol, and wherein the silanol is represented by
wherein R is independently alkyl, alkoxy or aryl; and wherein the silanol is present, for example, in an amount of from about 1 to about 10 weight percent; 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 wherein the photogenerating layer contains a mixture of a hydroxygallium phthalocyanine, a hydroxyaluminum phthalocyanine and a silanol, and wherein the silanol is selected, for example, from the group comprised of at least one of the following formulas/structures
and wherein R and R′ are independently selected from the group consisting of alkyl with from about 1 to about 6 carbon atoms, alkoxy, aryl with from about 6 to about 18 carbon atoms, and substituted derivatives thereof, and mixtures thereof, which silanols can also be referred to as polyhedral oligomeric silsesquioxane (POSS) silanols as illustrated with reference to the silanols encompassed by the following formulas/structures
or wherein R and R′ are independently selected from the group consisting of a suitable hydrocarbon, such as alkyl, with, for example, from 1 to about 25 carbon atoms, from 1 to about 12 carbon atoms, from 1 to about 6 carbon atoms, alkoxy with, for example, from 1 to about 25 carbon atoms, from 1 to about 12 carbon atoms, from 1 to about 6 carbon atoms; aryl with, for example, from 6 to about 42 carbon atoms, from 6 to about 36 carbon atoms, from 6 to about 24 carbon atoms, from 6 to about 18 carbon atoms, from 6 to about 12 carbon atoms, like methyl, ethyl, propyl, butyl, pentyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, vinyl, allyl, isobutyl, isooctyl, cyclopentyl, cyclohexyl, cyclohexenyl-3-ethyl, epoxycyclohexyl-4-ethyl, fluorinated alkyl such as CF3CH2CH2— and CF3(CF2)5CH2CH2—, methacrylolpropyl, norbornenylethyl, and the like, phenyl, benzyl, anthrayl; more specifically, R group examples, in embodiments, are phenyl, isobutyl, isooctyl, cyclopentyl, cyclohexyl, and the like; R′ group examples are methyl, vinyl, fluorinated alkyl, and the like; an imaging member comprising a supporting substrate, a photogenerating layer thereover comprised of a mixture of a hydroxyaluminum phthalocyanine, a hydroxygallium phthalocyanine, especially hydroxygallium phthalocyanine Type V, and a silanol, and a charge transport layer comprised of at least one charge transport component, and wherein the silanol is as illustrated herein, and more specifically, where the silanol R substituent is, for example, a vinyl, allyl, isobutyl, isooctyl, cyclopentyl, cyclohexyl, cyclohexenyl-3-ethyl, epoxycyclohexyl-4-ethyl, fluorinated alkyl such as CF3CH2CH2— and CF3(CF2)5CH2CH2—, methacrylolpropyl, or norbornenylethyl; a photoconductive member comprised of a substrate, a photogenerating layer thereover wherein the photogenerating layer contains a hydroxygallium phthalocyanine Type V, a hydroxyaluminum phthalocyanine, and a POSS silanol, at least one to about three charge transport layers thereover, a hole blocking layer, an adhesive layer wherein, in embodiments, the adhesive layer is situated between the photogenerating layer and the hole blocking layer; 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 the photogenerating layer contains a mixture of a hydroxyaluminum phthalocyanine, Type V hydroxygallium phthalocyanine, and a silanol (HOAIPc/HOGaPc/silanol photogenerating layer); a photoconductor wherein the charge transport component is comprised of aryl amines of the formulas
wherein X is selected from the group consisting of alkyl, alkoxy, aryl, and halogen; and a photoconductor wherein the charge transport component is comprised of aryl amines of the formulas
wherein X, Y and Z are independently selected from the group consisting of alkyl, alkoxy, aryl, and halogen.
Examples of silanols include POSS silanols wherein throughout POSS refers to a polyhedral oligomeric silsesquioxane. Examples of POSS silanols can be selected from the group consisting of isobutyl-POSS cyclohexenyl dimethylsilyldisilanol or isobutyl-polyhedral oligomeric silsesquioxane cyclohexenyl dimethylsilyldisilanol (C38H84O12Si8), cyclopentyl-POSS dimethylphenyldisilanol (C43H76O12Si8), cyclohexyl-POSS dimethylvinyldisilanol (C46H88O12Si8), cyclopentyl-POSS dimethylvinyldisilanol (C39H74O12Si8), isobutyl-POSS dimethylvinyldisilanol (C32H74O12Si8), cyclopentyl-POSS disilanol (C40H74O13Si8), isobutyl-POSS disilanol (C32H74O13Si8), isobutyl-POSS epoxycyclohexyldisilanol (C38H84O13Si8), cyclopentyl-POSS fluoro(3)disilanol (C40H75F3O12Si8), cyclopentyl-POSS fluoro(13)disilanol (C45H75F13O12Si8), isobutyl-POSS fluoro(13)disilanol (C38H75F13O12Si8), cyclohexyl-POSS methacryldisilanol (O51H96O14Si8), cyclopentyl-POSS methacryldisilanol (C44H82O14Si8), isobutyl-POSS methacryldisilanol (C37H82O14Si8), cyclohexyl-POSS monosilanol (C42H78O13Si8), cyclopentyl-POSS monosilanol (Schwabinol, C35H64O13Si8), isobutyl-POSS monosilanol (C28H64O13Si8), cyclohexyl-POSS norbornenylethyldisilanol (C53H98O12Si8), cyclopentyl-POSS norbornenylethyldisilanol (C46H84O12Si8), isobutyl-POSS norbornenylethyldisilanol (C39H84O12Si8), cyclohexyl-POSS TMS disilanol (C45H88O12Si8), isobutyl-POSS TMS disilanol (O31H74O12Si8), cyclohexyl-POSS trisilanol (C42H80O12Si7), cyclopentyl-POSS trisilanol (C35H66O12Si7), isobutyl-POSS trisilanol (C28H66O12Si7), isooctyl-POSS trisilanol (C56H122O12Si7), phenyl-POSS trisilanol (C42H38O12Si7), and the like, and mixtures thereof, all commercially available from Hybrid Plastics, Fountain Valley, Calif. In embodiments, the POSS silanol is a phenyl-POSS trisilanol, or phenyl-polyhedral oligomeric silsesquioxane trisilanol, a isooctyl-POSS trisilanol (C56H122O12Si7), or isooctyl-polyhedral oligomeric silsesquioxane trisilanol of the following formula/structures
where R is phenyl or isooctyl. The POSS silanol can contain from about 7 to about 20 silicon atoms, or from about 7 to about 12 silicon atoms. The MW of the POSS silanol is, for example, from about 700 to about 2,000, or from about 800 to about 1,300.
The silanols selected for the members, and photoconductors illustrated herein are stable primarily in view of the Si—OH substituents in that these substituents eliminate water to form siloxanes, which are Si—O—Si linkages. While not being limited by theory, it is believed that in view of the silanol hindered structures at the other three bonds attached to the silicon are stable for extended time periods, such as from at least one week to over one year.
In specific embodiments, the photoconductors illustrated herein contain in the photogenerating layer a mixture of a trisilanolisooctyl POSS (SO1455), trisilanolphenyl POSS (SO1458), trisilanolisobutyl POSS (SO1450), trisilanolcyclohexyl POSS (SO1400), and trisilanolcyclopentyl POSS (SO1430), all commercially available from, for example Hybrid Plastics Company.
There is disclosed a photoconductive imaging member comprised of a supporting substrate, a photogenerating layer thereover, a charge transport layer, and an overcoating 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 overcoating charge transport layer, and where the transport layer is of a thickness of from about 20 to about 75 microns; a member wherein the silanol, or mixtures thereof is present in an amount of from about 0.1 to about 30 weight percent, or from about 1 to about 10 weight percent; a photoconductor wherein the photogenerating layer contains a mixture of a hydroxygallium phthalocyanine, especially Type V hydroxygallium phthalocyanine, a hydroxyaluminum phthalocyanine, and a polymer binder at various ratios, such as for example 52.9/0.01/47, and also contained in the mixture a silanol in various amounts, such as from about 0.1 to about 25 weight percent, from 1 to about 15 weight percent, from 1 to about 10 weight percent, from 1 to about 5 weight percent (from about to about includes throughout all values in between about and about), a photoconductor 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 photoconductor wherein the photogenerating binder is present in an amount of from about 5 to about 80 percent by weight, and wherein the total of all photogenerating layer components is about 100 percent; 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 layer resinous binder is selected from the group consisting of known suitable polymers like polyesters, copolymers of vinyl chloride and vinyl acetate, poly(vinyl chloride-co-vinyl acetate-co-maleic acid), poly(vinyl butyral)s, polycarbonates, polystyrene-b-poly(vinyl pyridine), and poly(vinyl formal)s; an imaging member wherein each of the charge transport layers, especially a first and second layer, comprises
wherein X is selected from the group consisting of alkyl, alkoxy, and halogen, such as methyl and chloride; 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 and Y are independently alkyl, alkoxy, aryl, a halogen, or mixtures thereof; an imaging member 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 and polystyrene; a photoconductor wherein the hydroxygallium phthalocyanine photogenerating pigment present is Type V hydroxygallium phthalocyanine prepared by hydrolyzing a gallium phthalocyanine precursor by dissolving the chlorogallium 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 hydroxygallium phthalocyanine Type V; an imaging member wherein the hydroxygallium phthalocyanine Type V has major peaks, as measured with an X-ray diffractometer, at Bragg angles (2θ±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 0.1 to about 10 microns; a member wherein the photogenerating pigment component mixture 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 0.5 to about 5 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; wherein the photogenerating layer resinous binder is selected from the group consisting of polyesters, copolymers of vinyl chloride and vinyl acetate, poly(vinyl chloride-co-vinyl acetate-co-maleic acid), poly(vinyl butyral)s, polycarbonates, polystyrene-b-poly(vinyl pyridine), and poly(vinyl formal)s; a photoconductor wherein the charge transport layer contains a hole transport molecule 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, or N,N′-diphenyl-N,N′-bis(3-chlorophenyl)-[p-terphenyl]-4,4″-diamine molecules, and wherein the hole transport layer resinous binder is selected from the group consisting of polycarbonates, polyarylates, and polystyrenes; 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 overcoating 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 is selected, such as for example, from 2 to about 10, and more specifically, 1 or 2 layers, and where imaging member refers, for example, to a photoconductor that can be used in a xerographic printing machine.
In embodiments thereof, the silanol can be added to the hydroxygallium phthalocyanine and hydroxyaluminum phthalocyanine mixture, and where the resulting photoconductor exhibits a number of advantages, such as faster PIDC as compared to a photoconductor where the photogenerating layer is free of a silanol; and lower CDS/background as compared to a similar photoconductor where the photogenerating layer is free of the silanol.
The trisilanolphenyl POSS, or phenyl-POSS trisilanol (C42H38O12Si7) and the trisilanolisooctyl POSS, or isooctyl-POSS trisilanol (C56H122O12Si7), which are represented by
where R is phenyl or isooctyl, can be added to the photogenerating layer mixture.
The Type I hydroxygallium phthalocyanine can be generated by known methods, such as those illustrated in the relevant patents referenced herein, and more specifically, by the reaction of gallium chloride with 1,3-diiminoisoindolene in certain solvents like n-methylpyrrolidone, or the reaction of a mixture of phthalonitrile and gallium chloride with a chloronaphthalene solvent to form Type I; and wherein Type V hydroxygallium phthalocyanine is converted from the prepared Type I hydroxygallium phthalocyanine, and in embodiments, the preparation of hydroxygallium phthalocyanine polymorphs which comprises the synthesis of a halo, especially chlorogallium phthalocyanine, hydrolysis thereof, and conversion in the presence of a silanol of the hydroxygallium phthalocyanine Type I obtained to Type V hydroxygallium phthalocyanine. In embodiments, preparation of the precursor pigment halo, especially chlorogallium phthalocyanine Type I, can result in photogenerating pigments, specifically hydroxygallium phthalocyanine Type V with low levels of chlorine of, in embodiments, less than about 1 percent, and more specifically, from about 0.05 to about 0.80 percent. The hydroxygallium phthalocyanine products can be identified by various known means including X-ray powder diffraction (XRPD).
In embodiments, the preparation of the precursor halo, especially chlorogallium phthalocyanine, can be accomplished by the reaction of a halo, especially chlorogallium, with diiminoisoindolene and an organic solvent like N-methylpyrrolidone, followed by washing with, for example, a solvent like dimethylformamide (DMF). The precursor obtained can be identified as chlorogallium phthalocyanine Type I on the basis of its XRPD trace. Thereafter, the precursor is subjected to hydrolysis by heating in the presence of a strong acid like sulfuric acid, and subsequently reprecipitating the dissolved pigment by mixing with a basic solution like ammonium hydroxide, and isolating the resulting pigment, which can be identified as Type I hydroxygallium phthalocyanine on the basis of its XRPD trace. The obtained Type I is then converted to Type V hydroxygallium phthalocyanine by adding thereto a solvent component like N,N-dimethylformamide, and subsequently stirring or alternatively milling in a closed container on an appropriate instrument, for example a ball mill, at room temperature, approximately 25° C., for a period of from about 8 hours to 1 week, and preferably about 24 hours. The pigment precursor Type I chlorogallium phthalocyanine can be prepared by the reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, present in an amount of from about 10 to about 100 parts, and more specifically, about 19 parts, with 1,3-diiminoisoindolene in an amount of from about 1 to about 10 parts, and preferably about 4 parts of DI for each part of gallium chloride that is reacted, and wherein in embodiments the reaction is accomplished by heating at, for example, about 200° C. When the resulting pigment precursor chlorogallium phthalocyanine Type I is hydrolyzed by, 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, the hydrolyzed pigment contains very low levels of residual chlorine of from about 0.001 to about 0.1 percent, and in embodiments of from about 0.03 percent of the weight of the Type I hydroxygallium phthalocyanine pigment, as determined by elemental analysis.
The hydroxygallium phthalocyanine Type V can be formed, in embodiments, from the Type I hydroxygallium phthalocyanine by the reaction of 1 part of gallium chloride with from about 3 to about 12 parts, and more specifically, about 5 parts of 1,3-diiminoisoindolene in a solvent, such as N-methylpyrrolidone, in an amount of from about 10 to about 100 parts, and more specifically, about 19 parts, for each part of gallium chloride that is used, provides a crude Type I chlorogallium phthalocyanine, which is subsequently washed with a component, such as dimethyl formamide, to provide a pure form of Type I chlorogallium phthalocyanine as determined by X-ray powder diffraction; then dissolving 1 weight part of the resulting chlorogallium phthalocyanine in concentrated, about 94 percent, sulfuric acid in an amount of from about 1 to about 100 weight parts, and in an embodiment about 5 weight parts, by stirring the pigment in the acid for an effective period of time, from about 1 to about 20 hours, and in an embodiment about 2 hours at a temperature of from about 0° C. to about 75° C., and more specifically, about 40° C. in air or under an inert atmosphere, such as argon or nitrogen; adding the resulting mixture to a stirred organic solvent in a dropwise manner at a rate of about 0.5 to about 10 milliliters per minute, and in an embodiment about 1 milliliter per minute to a nonsolvent, which can be a mixture comprised of from about 1 to about 10 volume parts, and more specifically, about 4 volume parts of concentrated aqueous ammonia solution (14.8 N) and from about 1 to about 10 volume parts, and more specifically, about 7 volume parts of water, for each volume part of sulfuric acid that was used, which solvent mixture was chilled to a temperature of from about −25° C. to about 10° C., and in an embodiment about −5° C. while being stirred at a rate sufficient to create a vortex extending to the bottom of the flask containing the solvent mixture; isolating the resulting blue pigment by, for example, filtration; and washing the hydroxygallium phthalocyanine product obtained with deionized water by redispersing and filtering from portions of deionized water, which portions are from about 10 to about 400 volume parts, and in an embodiment about 200 volume parts for each weight part of the precursor pigment chlorogallium phthalocyanine Type I. The product, a dark blue solid, was confirmed to be Type I hydroxygallium phthalocyanine on the basis of its X-ray powder diffraction pattern having major peaks at 6.9, 13.1, 16.4, 21.0, 26.4, and the highest peak at 6.9 degrees 2θ. The Type I hydroxygallium phthalocyanine product obtained can then be added to an organic solvent, such as N,N-dimethylformamide, by, for example, ball milling the Type I hydroxygallium phthalocyanine pigment mixture 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 to obtain the hydroxygallium phthalocyanine Type V in a purity of up to about 99.5 percent, and with minimal chlorine content.
In embodiments, a process for the preparation of Type V hydroxygallium phthalocyanines comprises 1) the addition of 1 part of gallium chloride to a stirred solvent of N-methylpyrrolidone present in an amount of from about 10 to about 100 parts, and more specifically, about 19 parts with from about 1 to about 10 parts, and more specifically, about 4 parts of 1,3-diiminoisoindolene; 2) relatively slow application of heat using an appropriate sized heating mantle at a rate of about 1 to about 10 degrees per minute, and more specifically, about 5 degrees per minute until refluxing occurs at a temperature of about 200° C.; 3) continued stirring at the reflux temperature for a period of about 0.5 to about 8 hours, and more specifically, about 4 hours; 4) cooling of the reactants to a temperature of about 130° C. to about 180° C., and more specifically, about 160° C. by removal of the heat source; 5) filtration of the flask contents through, for example, an M-porosity sintered glass funnel which was preheated using a solvent which is capable of raising the temperature of the funnel to about 150° C., for example, boiling N,N-dimethyl formamide (DMF) in an amount sufficient to completely cover the resulting purple solid by slurrying the solid in portions of boiling DMF either in the funnel or in a separate vessel in a ratio of about 1 to about 10 times, and more specifically, about 3 times the volume of the solid being washed until the hot filtrate became light blue in color; cooling and further washing the solid of impurities by slurrying the solid in several portions of N,N-dimethyl formamide at room temperature, about 25° C., approximately equivalent to about three times the volume of the solid being washed until the filtrate became light blue in color; washing the solid of impurities by slurrying in portions of an organic solvent, such as methanol, acetone, water and the like, and in an embodiment methanol at room temperature, about 25° C., approximately equivalent to about three times the volume of the solid being washed until the filtrate became light blue in color; oven drying the solid in the presence of a vacuum or in air at a temperature of from about 25° C. to about 200° C., and more specifically, about 70° C. for a period of from about 2 to about 48 hours, and more specifically, about 24 hours, thereby resulting in the isolation of a shiny purple solid which was identified as being Type I chlorogallium phthalocyanine by its X-ray powder diffraction trace, having major peaks at 9.1, 11.0, 18.8, 20.3, and the highest peak at 27 degrees 2θ. The Type I chlorogallium phthalocyanine can then be converted to the corresponding hydroxygallium phthalocyanine as illustrated herein, and then subsequently converting the Type I hydroxygallium phthalocyanine into Type V hydroxygallium phthalocyanine.
Also, in embodiments, there can be selected for the processes illustrated herein, and wherein, for example, hydroxygallium Type V, free of chlorine, can be obtained by selecting a mixture of DI3 and phthalonitrile in place of DI3 alone. More specifically, the pigment precursor chlorogallium phthalocyanine Type I can be prepared by the reaction of 2 parts gallium chloride with a mixture comprised of from about 1 to about 7 parts, and more specifically, about 1 part of DI3 (1,3-diiminoisoindolene), and from about 1 to about 10 parts, and more specifically, about 3 parts of o-phthalonitrile in the presence of a suitable solvent like N-methyl pyrrolidone solvent, and more specifically, about 19 parts of solvent are selected. The resulting pigment was identified as being Type I chlorogallium phthalocyanine by its X-ray powder diffraction trace having major peaks at 9.1, 11.0, 18.8, 20.3, and the highest peak at 27 degrees 2θ. When this pigment precursor is hydrolyzed by, for example, acid pasting whereby the pigment precursor is dissolved in a concentrated acid, and more specifically 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, the hydrolyzed Type V pigment contains essentially no chlorine. It is believed that impurities, such as chlorine, in the photogenerating material can cause a reduction in the xerographic performance, and in particular, increased levels of dark decay and a negative impact on the cycling performance of layered photoconductive imaging members thereof.
In embodiments, the processes for the preparation of hydroxygallium phthalocyanine Type V comprises the reaction of 1 part of gallium chloride with a mixture comprised of about 1 part of 1,3-diiminoisoindolene, and about 4 parts of o-phthalonitrile in a solvent, such as N-methylpyrrolidone, present in an amount of from about 23 parts for each part of gallium chloride that is used thereby resulting in Type I chlorogallium phthalocyanine, which is subsequently washed with hot dimethylformamide, by slurrying the crude solid in portions of DMF at a temperature of from about 75° C. to about 150° C., and more specifically, about 150° C. either in a funnel or in a separate vessel in a ratio of about 1 to about 10 times, and more specifically, about 3 times the volume of the solid being washed until the hot filtrate became light blue in color to provide a pure form of chlorogallium phthalocyanine Type I as determined by X-ray powder diffraction; dissolving the resulting chlorogallium phthalocyanine Type I in concentrated sulfuric acid in an amount of from about 1 to about 100 weight parts, and in an embodiment about 5 weight parts of concentrated, about 94 percent, sulfuric acid by stirring the Type I pigment in the acid for an effective period of time, from about 30 seconds to about 24 hours, and in an embodiment, about 2 hours at a temperature of from about 0° C. to about 75° C., and more specifically, about 40° C. in air or under an inert atmosphere, such as argon or nitrogen; adding the dissolved precursor pigment chlorogallium phthalocyanine Type I in a dropwise manner at a rate of about 0.5 to about 10 milliliters per minute, and in an embodiment, about 1 milliliter per minute to a solvent mixture which enables reprecipitation of the dissolved pigment, which solvent can be a mixture comprised of from about 3 to about 10 volume parts, and more specifically, about 4 volume parts of concentrated aqueous ammonia solution (14.8 N), and from about 1 to about 10 volume parts, and more specifically, about 7 volume parts of water for each volume part of sulfuric acid that was used, which solvent mixture was chilled to a temperature of from about −25° C. to about 10° C., and in an embodiment, about −5° C. while being stirred at a rate sufficient to create a vortex extending to the bottom of the flask containing said solvent mixture; filtering the dark blue suspension through a glass fiber filter fitted in a porcelain funnel; washing the isolated solid by redispersing in water by stirring for a period of from about 1 minute to about 24 hours, and in an embodiment, about 1 hour in an amount of from about 10 to about 400 volume parts, and in an embodiment, about 200 volume parts relative to the original weight of the solid Type I pigment used, followed by filtration as illustrated herein, until the conductivity of the filtrate was measured as less than 20 μS; and drying the resulting blue pigment in air or in the presence of a vacuum at a temperature of from about 25° C. to about 200° C., and in an embodiment, in air at about 70° C. for a period of from about 5 minutes to about 48 hours, and in an embodiment, about 12 hours to afford a dark blue powder in a desirable yield of from about 80 to about 99 percent, and in an embodiment, about 97 percent, which has been identified as being Type I hydroxygallium phthalocyanine on the basis of its XRPD spectrum, having major peaks at 6.9, 13.1, 16.4, 21.0, 26.4, and the highest peak at 6.9 degrees 2θ. The Type I hydroxygallium phthalocyanine product so obtained can then be converted to Type V hydroxygallium phthalocyanine as illustrated herein.
The hydroxyaluminum phthalocyanine included in the photogenerating mixture is formed during the preparation of the hydroxygallium phthalocyanine, and where there is present from about 5 to about 1,000 parts per million, or from about 50 to about 500 parts per million of the hydroxyaluminum phthalocyanine, and which hydroxyaluminum phthalocyanine is commercially available from Aldrich Chemical, and can be simply added to the photogenerating mixture followed by stirring or milling. In embodiments, hydroxygallium phthalocyanine is present in the photogenerating mixture in an amount of, for example, from about 30 to about 80 weight percent, or from about 40 to about 70 weight percent of the photogenerating layer; the hydroxyaluminum phthalocyanine is present in the photogenerating mixture in an amount of, for example, from about 0.001 to about 0.1 weight percent, or from about 0.005 to about 0.05 weight percent of the photogenerating layer components; the silanol is present in the photogenerating layer mixture an amount of, for example, from about 0.1 to about 20 weight percent, or from about 1 to about 10 weight percent of the photogenerating layer components; and the polymeric binder, such as a polycarbonate, is present in the photogenerating layer mixture in an amount of, for example, from about 20 to about 70 weight percent, or from about 30 to about 60 weight percent of the photogenerating layer, and where the total of the four photogenerating layer components is about 100 percent.
The thickness of the photoconductor substrate layer depends on many factors, including economical considerations, electrical characteristics, and the like, thus this layer may be of a substantial thickness, for example over 3,000 microns, such as from about 300 to about 700 microns, 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 substrate may be opaque or substantially transparent, and may comprise any suitable material. 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, as disclosed in a copending application referenced herein, this layer may be of 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 substantial thickness of, for example, about 250 microns, or of 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, 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 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®.
The photogenerating hydroxygallium phthalocyanine, hydroxyaluminum phthalocyanine, and silanol mixture 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 materials 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 composition mixture is 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 layer binder resin is present in various suitable amounts of, for example, from about 10 to about 90 weight percent, and more specifically, from about 30 to about 70 weight percent, 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, ethers, alcohols, aromatic hydrocarbons, halogenated aliphatic hydrocarbons, silanols, 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.
In embodiments, examples of polymeric binder materials that can be selected as the matrix for the photogenerating layer mixture are thermoplastic and thermosetting resins, such as polycarbonates, polyesters, polyamides, polyurethanes, polystyrenes, polyarylsilanols, polyarylsulfones, polybutadienes, polysulfones, polysilanolsulfones, 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), 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, such that 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, the photogenerating mixture of a thickness, for example, of from about 0.1 to about 30 microns, or from about 0.4 to about 2 microns can be applied to or deposited on the substrate, on other surfaces situated 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, 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 are formed on the photogenerating 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, poly(vinyl butyral), phenolic-formaldehyde resins, melamine-formaldehyde resins, poly(vinyl alcohol), polyurethane, and polyacrylonitrile. This layer is, for example, of a thickness of from about 0.001 to about 10 microns, or from about 0.1 to about 2 microns. Optionally, this layer may contain effective suitable amounts, for example from about 1 to about 80 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 layers selected for the photoconductors 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 oxides, 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-phenylenediisopropylidene)bisphenol), S (4,4′-sulfonyldiphenol), 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 to about 80 weight percent, and more specifically, from about 55 to about 65 weight percent of a suitable component like a metal oxide, such as TiO2; from about 20 to about 70 weight percent, and more specifically, from about 25 to about 50 weight percent of a phenolic resin; from about 2 to about 20 weight percent, and more specifically, from about 5 to about 15 weight percent of a phenolic compound preferably containing at least two phenolic groups, such as bisphenol S, and from about 2 to about 15 weight percent, and more specifically, from about 4 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 nanometers. 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 to about 30 microns, and more specifically, from about 0.1 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 Borden 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.
Charge transport components and molecules include a number of known materials, such as aryl amines, and which layer is generally of a thickness of from about 5 microns to about 80 microns, and more specifically, of a thickness of from about 10 microns to about 40 microns, wherein the charge transport components include molecules of the following formula
wherein X is alkyl, alkoxy, aryl, a halogen, or mixtures thereof, and especially those substituents selected from the group consisting of Cl and CH3; and molecules of the following formula
wherein X and Y are independently alkyl, alkoxy, aryl, a halogen, or mixtures thereof.
Alkyl and alkoxy contain, for example, from 1 to about 25 carbon atoms, and more specifically, from 1 to about 12 carbon atoms, such as methyl, ethyl, propyl, butyl, pentyl, and the corresponding alkoxides. Aryl can contain from 6 to about 36 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 selected for the CTL 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 the binder materials 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′-cyclohexylidinediphenylene)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 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 preferred. 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 and silanol are 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 charge transporting molecules, especially for the first and second charge transport layers, 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, N,N′-bis(4-butyl phenyl)-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-diethyl amino 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 high efficiency, and transports them across the charge transport layer with short transit times, and which layer contains a binder and a silanol 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.
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 5 to about 75 microns, but 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, and thus selectively discharging the surface charge on the surface of the active layer.
The thickness of the continuous charge transport overcoat layer selected depends upon the abrasiveness of the charging (bias charging roll), cleaning (blade or web), development (brush), transfer (bias transfer roll), and the like in the system employed, and can be up to about 10 microns. In embodiments, this thickness for each layer is from about 1 to about 5 microns. Various suitable and conventional methods may be used to mix, and thereafter apply the overcoat layer 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 deposited coating may be effected by any suitable conventional technique, such as oven drying, infrared radiation drying, air drying, and the like. The dried overcoating layer of this disclosure should transport holes during imaging and should not have too high a free carrier concentration.
The overcoat or top charge transport layer can comprise the same components as the charge transport layer wherein the weight ratio between the charge transporting small molecules, and the suitable electrically inactive resin binder is less, such as for example, from about 0/100 to about 60/40, or from about 20/80 to about 40/60.
Examples of components or materials optionally incorporated into the charge transport layers or at least one charge transport layer to, for example, enable improved 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, NW, BP-76, BP-101, GA-80, GM and GS (available from Sumitomo Chemical Company, 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 Company, 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.
Primarily for purposes of brevity, the examples of each of the substituents, and each of the components/compounds/molecules, polymers, (components) for each of the layers specifically disclosed herein are not intended to be exhaustive. Thus, a number of components, polymers, formulas, structures, and R group or substituent examples, and carbon chain lengths not specifically disclosed or claimed are intended to be encompassed by the present disclosure and claims. Also, the carbon chain lengths are intended to include all numbers between those disclosed, claimed or envisioned, thus from 1 to about 20 carbon atoms, and from 6 to about 36 carbon atoms includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, up to 36, or more. Similarly, the thickness of each of the layers, the examples of components in each of the layers, the amount ranges of each of the components disclosed and claimed is not exhaustive, and it is intended that the present disclosure and claims encompass other suitable parameters not disclosed or that may be envisioned.
The following Examples are being submitted to illustrate embodiments of the present disclosure. Also, parts and percentages are by weight unless otherwise indicated. A Comparative Example and data are also presented.
An imaging member (photoconductor) was prepared by providing a 0.02 micron thick titanium layer coated (the coater device) on a biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000) having a thickness of 3.5 mils, and applying thereon, with 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 an extrusion coater, and which adhesive contains 0.2 percent by weight based on the total weight of the solution of 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 (HOGaPc, Type V), 0.024 gram of hydroxyaluminum phthalocyanine (HOAIPc), and 300 grams of ⅛-inch (3.2 millimeters) diameter stainless steel shot. This mixture was then placed on an attritor 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/hydroxyaluminum phthalocyanine dispersion. This slurry was then placed on a shaker for 10 minutes. The resulting dispersion was, thereafter, applied to the above adhesive interface with an extrusion coater 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 135° C. for 5 minutes in a forced air oven to form a dry photogenerating layer of HOGaPc/HOAIPc/PCZ-200=56.4/0.6/43 having a thickness of 0.4 micron.
The resulting imaging member web was then overcoated with a two-layer charge transport layer. Specifically, the photogenerating layer was overcoated with a charge transport layer (the bottom layer) in contact with the photogenerating layer. The bottom layer of the charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 0.5:0.5 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 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 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 bottom layer of the charge transport layer to form a coating that upon drying (120° C. for 1 minute) had a thickness of 14.5 microns. During this coating process, the humidity was equal to or less than 15 percent.
A photoconductor was prepared by repeating the process of Comparative Example 1 except that there was added to the photogenerating layer mixture 0.04 gram of the silanol, trisilanolisooctyl POSS (C56H122O12Si7, SO1455 obtained from Hybrid Plastics Company). The resulting photogenerating layer comprised HOGaPc/HOAIPc/PCZ-200/silanol in a ratio of 55.8/0.6/42.6/1.
A photoconductor was prepared by repeating the process of Comparative Example 1 except that there was added to the photogenerating layer mixture 0.12 gram of the silanol, trisilanolisooctyl POSS (C56H122O12Si7, SO1455 obtained from Hybrid Plastics Company). The resulting photogenerating layer comprised HOGaPc/HOAIPc/PCZ-200/silanol in a ratio of 54.7/0.6/41.7/3.
A photoconductor was prepared by repeating the process of Comparative Example 1 except that there was added to the photogenerating layer mixture 0.2 gram of the silanol, trisilanolisooctyl POSS (C56H122O12Si7, SO1455 obtained from Hybrid Plastics Company). The resulting photogenerating layer comprised HOGaPc/HOAIPc/PCZ-200/silanol in a ratio of 53.7/0.6/41/4.7.
A number of photoconductors are prepared by repeating the process of Example III except there is selected the silanol, trisilanolphenyl POSS (SO1458), trisilanolisobutyl POSS (SO1450), trisilanolcyclohexyl POSS (SO1400), or trisilanolcyclopentyl POSS (SO1430), all commercially available from Hybrid Plastics, in place of the trisilanolisooctyl POSS of Example I.
The above prepared photoconductors of Comparative Example 1 and Examples I, II and III 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 devices were tested at surface potentials of 500 volts with the exposure light intensity incrementally increased by means of regulating a series of neutral density filters; the exposure light source was a 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.).
V (1 erg/cm2) represents the surface potential of the photoconductors when the exposure is 1 erg/cm2, and this is used to characterize the PIDC. The smaller the V (1 erg/cm2), the faster or quicker the PIDC.
With incorporation of the silanol into the HOGaPc/HOAIPc photogenerating layer, the V (1 erg/cm2) was reduced by about 20 to about 50 volts depending on the concentration of the silanol.
Various known methods have been developed to assess and/or accommodate the occurrence of charge deficient spots. For example, U.S. Pat. Nos. 5,703,487 and 6,008,653, the disclosures of each patent being totally incorporated herein by reference, disclose processes for ascertaining the microdefect levels of an electrophotographic imaging member.
The method of U.S. Pat. No. 5,703,487 designated as field-induced dark decay (FIDD) involves measuring either the differential increase in charge over and above the capacitive value, or measuring reduction in voltage below the capacitive value of a known imaging member and of a virgin imaging member, and comparing differential increase in charge over and above the capacitive value, or the reduction in voltage below the capacitive value of the known imaging member and of the virgin imaging member.
U.S. Pat. Nos. 6,008,653 and 6,150,824, the disclosures of each patent being totally incorporated herein by reference, disclose a method for detecting surface potential charge patterns in an electrophotographic imaging member with a floating probe scanner. Floating Probe Micro Defect Scanner (FPS) is a contactless process for detecting surface potential charge patterns in an electrophotographic imaging member. The scanner includes a capacitive probe having an outer shield electrode, which maintains the probe adjacent to and spaced from the imaging surface to form a parallel plate capacitor with a gas between the probe and the imaging surface, a probe amplifier optically coupled to the probe, establishing relative movement between the probe and the imaging surface, and a floating fixture which maintains a substantially constant distance between the probe and the imaging surface. A constant voltage charge is applied to the imaging surface prior to relative movement of the probe and the imaging surface past each other, and the probe is synchronously biased to within about +/−300 volts of the average surface potential of the imaging surface to prevent breakdown, measuring variations in surface potential with the probe, compensating the surface potential variations for variations in distance between the probe and the imaging surface, and comparing the compensated voltage values to a baseline voltage value to detect charge patterns in the electrophotographic imaging member. This process may be conducted with a contactless scanning system comprising a high resolution capacitive probe, a low spatial resolution electrostatic voltmeter coupled to a bias voltage amplifier, and an imaging member having an imaging surface capacitively coupled to and spaced from the probe and the voltmeter. The probe comprises an inner electrode surrounded by and insulated from a coaxial outer Faraday shield electrode, the inner electrode connected to an opto-coupled amplifier, and the Faraday shield connected to the bias voltage amplifier. A threshold of 20 volts is commonly chosen to count charge deficient spots. The above prepared photoconductors of Comparative Example 1 and Examples I, II and III were measured for CDS counts using the above-described FPS technique, and the results also are provided in Table 1.
Incorporation of the silanol into the HOGaPc/HOAIPc photogenerating layer had no detrimental effect on CDS, however, the silanol accelerated the PIDC, that is a lower V (1 erg/cm2) (less charge trapping which results in minimal ghosting properties for the developed xerographic image), for example, from about 20 to 50 volts lower for the Example I and II photoconductors as compared to the Comparative Example 1 photoconductor, or a photoconductor that is free of the silanol and the hydroxyaluminum phthalocyanine.
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.
