Patent Application
20070298342
Disclosed are imaging members with many of the advantages illustrated herein, such as extended lifetimes of service of, for example, in excess of about 3,000,000 imaging cycles; rapid charge transfer to thereby improve print quality caused by temperature variation in proximity to the photoconductor; excellent electrical characteristics, for example high sensitivity; stable electrical properties; low image ghosting; resistance to charge transport layer cracking upon exposure to the vapor of certain solvents; excellent surface characteristics; improved 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 (Photoinduced Discharge Curve), and the like.
Also disclosed are layered photoresponsive imaging members, which are responsive to near infrared radiation of from about 700 to about 900 nanometers.
Further disclosed are drum or layered flexible photoresponsive imaging members.
Moreover, disclosed are layered belt and drum photoresponsive or photoconductive imaging members with mechanically robust and solvent resistant charge transport layers with rapid transport of charge, especially holes.
Additionally disclosed are flexible imaging members with optional hole blocking layers comprised of metal oxides, phenolic resins, and optional phenolic compounds, and which phenolic compounds contain at least two, and more specifically, two to ten phenol groups or phenolic resins with, for example, a weight average molecular weight ranging from about 500 to about 3,000, permitting, for example, a hole blocking layer with excellent efficient electron transport which usually results in a desirable photoconductor low residual potential Vlow.
Also disclosed are photoconductors with rapid charge transporting characteristics, high and stable, with a minimum or no PDIC change, photosensitivity, and which sensitivity is in embodiments about 50 percent higher than similar photoconductors that contain, for example, in the photogenerating layer a hydroxygallium phthalocyanine.
In an electrostatographic reproducing apparatus for which the photoconductors disclosed herein may be selected, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles, which are commonly referred to as toner. Specifically, the photoreceptor is charged on its surface by means of an electrical charger to which a voltage has been supplied from a power supply. The photoreceptor is then imagewise exposed to light from an optical system or an image input apparatus, such as a laser and light emitting diode, to form an electrostatic latent image thereon. Generally, the electrostatic latent image is developed by a developer mixture of toner and carrier particles. Development can be accomplished by known processes, such as a magnetic brush, powder cloud, highly agitated zone development, or other known development process.
After the toner particles have been deposited on the photoconductive surface in image configuration, they are transferred to a copy sheet by a transfer means, which can be pressure transfer or electrostatic transfer. In embodiments, the developed image can be transferred to an intermediate transfer member, and subsequently transferred to a copy sheet.
When the transfer of the developed image is completed, a copy sheet advances to a fusing station with fusing and pressure rolls wherein the developed image is fused to the copy sheet by passing the copy sheet between the fusing member and the pressure member, thereby forming a permanent image. Fusing may be accomplished by other fusing members, such as a fusing belt in pressure contact with a pressure roller, fusing roller in contact with a pressure belt, or other like systems.
Aspects of the present disclosure relate to a photoconductor containing an optional supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component wherein the at least one charge transport component is comprised of aryl amine molecules of the formula
wherein X and Y each independently represents a suitable hydrocarbon like alkyl, alkoxy, aryl, a halogen, or optionally mixtures thereof, and wherein the photogenerating layer contains a titanyl phthalocyanine prepared by dissolving a Type I titanyl phthalocyanine in a solution comprising a trihaloacetic acid and an alkylene halide; adding the 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 monohalobenzene; a photoconductor comprised of a substrate, a photogenerating layer thereover, and a plurality of charge transport layers wherein the at least one plurality contains a charge transport component of the formula/structure
wherein X and Y are each independently alkyl, alkoxy, aryl, or a halogen, and wherein the photogenerating layer contains a titanyl phthalocyanine Type V prepared by dissolving a Type I titanyl phthalocyanine in a solution comprising a trihaloacetic acid and an alkylene halide; adding the mixture to a solution comprising an alcohol and an alkylene halide thereby precipitating a Type Y titanyl phthalocyanine; and contacting the Type Y titanyl phthalocyanine with a monohalobenzene; and optionally wherein the at least one charge transport layer includes an antioxidant; and a photoconductor comprised of a substrate, a photogenerating layer, and a plurality of charge transport layers wherein at least one charge layer transport is comprised of at least one component of the formula/structure
wherein X and Y are each independently alkyl, alkoxy, aryl, or a halogen, wherein the photogenerating layer contains a titanyl phthalocyanine Type V, and in embodiments wherein a thiophosphate is present in at least one of the photogenerating layer and charge transport layer.
The photogenerating layer in embodiments is comprised of high photosensitivity titanyl phthalocyanines prepared as illustrated herein, and in copending application U.S. application Ser. No. 10/992,500, U.S. Publication No. 2006010524 (Attorney Docket No. 20040735), the disclosure of which is totally incorporated herein by reference. In embodiments, the Type V phthalocyanine can be generated by dissolving Type I titanyl phthalocyanine in a solution comprising a trihaloacetic acid and an alkylene halide; adding the resulting mixture comprising the dissolved Type I titanyl phthalocyanine to a solution comprising an alcohol and an alkylene halide thereby precipitating a Type Y titanyl phthalocyanine; and treating the resulting Type Y titanyl phthalocyanine with monochlorobenzene.
With further respect to the titanyl phthalocyanines selected for the photogenerating layer, such phthalocyanines exhibit a crystal phase that is distinguishable from other known titanyl phthalocyanine polymorphs, and are designated as Type V polymorphs prepared by converting a Type I titanyl phthalocyanine to a Type V titanyl phthalocyanine pigment. The processes include converting a Type I titanyl phthalocyanine to an intermediate titanyl phthalocyanine, which is designated as a Type Y titanyl phthalocyanine, and then subsequently converting the Type Y titanyl phthalocyanine to a Type V titanyl phthalocyanine.
In one embodiment, the process comprises: (a) dissolving a Type I titanyl phthalocyanine in a suitable solvent; (b) adding the solvent solution comprising the dissolved Type I titanyl phthalocyanine to a quenching solvent system to precipitate an intermediate titanyl phthalocyanine (designated as a Type Y titanyl phthalocyanine); and (c) treating the resultant Type Y phthalocyanine with a halo, such as, for example, monochlorobenzene to obtain a resultant high sensitivity titanyl phthalocyanine, which is designated herein as a Type V titanyl phthalocyanine. In another embodiment, prior to treating the Type Y phthalocyanine with a halo, such as monochlorobenzene, the Type Y titanyl phthalocyanine may be washed with various solvents including, for example, water, and/or methanol. The quenching solvents system to which the solution comprising the dissolved Type I titanyl phthalocyanine is added comprises, for example, an alkyl alcohol and an alkylene halide.
The process further provides a titanyl phthalocyanine having a crystal phase distinguishable from other known titanyl phthalocyanines. The titanyl phthalocyanine Type V prepared by a process according to the present disclosure is distinguishable from, for example, Type IV titanyl phthalocyanines in that a Type V titanyl phthalocyanine exhibits an X-ray powder diffraction spectrum having four characteristic peaks at 9.0°, 9.6°, 24.0°, and 27.2°, while Type IV titanyl phthalocyanines typically exhibit only three characteristic peaks at 9.6°, 24.0°, and 27.2°.
A number of Type I titanyl phthalocyanines may be selected for the generation of the Type V titanyl phthalocyanine, such as the Type 1s prepared as illustrated in U.S. Pat. Nos. 5,153,094; 5,166,339; 5,189,155; and 5,189,156, the disclosures of which are totally incorporated herein by reference.
More specifically, a Type I titanyl phthalocyanine may be prepared, in embodiments, by the reaction of DI3 (1,3-diiminoisoindolene) and tetrabutoxide in the presence of 1-chloronaphthalene solvent, whereby there is obtained a crude Type I titanyl phthalocyanine, which is subsequently purified up to about a 99.5 percent purity by washing with, for example, dimethylformamide.
In another embodiment, for example, a Type I titanyl phthalocyanine can also be prepared by i) the addition of 1 part titanium tetrabutoxide to a stirred solution of from about 1 part to about 10 parts, and in embodiments about 4 parts of 1,3-diiminoisoindolene; ii) relatively slow application of heat using an appropriate sized heating mantle at a rate of about 1° per minute to about 10° per minute and, in embodiments, about 5° per minute until refluxing occurs at a temperature of about 130° C. to about 180° C. (all temperatures are in Centigrade unless otherwise indicated); iii) removal and collection of the resulting distillate, which was shown by NMR spectroscopy to be butyl alcohol, in a dropwise fashion using an appropriate apparatus, such as a Claisen Head condenser, until the temperature of the reactants reaches from 190° C. to about 230° C., and in embodiments, about 200° C.; iv) continued stirring at the reflux temperature for a period of about ½ hour to about 8 hours, and in embodiments, about 2 hours; v) cooling of the reactants to a temperature of about 130° C. to about 180° C., and in embodiments, about 160° C. by removal of the heat source; vi) filtration of the flask contents through, for example, an M-porosity (10 to 15 microns) 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-dimethylformamide in an amount sufficient to completely cover the bottom of the filter funnel so as to prevent blockage of said funnel; vii) washing 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, and preferably about 3 times the volume of the solid being washed, until the hot filtrate became light blue in color; viii) cooling and further washing the solid of impurities by slurrying the solid in portions of N,N-dimethylformamide at room temperature, about 25 degrees, approximately equivalent to about three times blue in color; ix) washing the solid of impurities by slurrying the solid in portions of an organic solvent, such as methanol, acetone, water and the like, and in this 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; x) oven drying the purple solid in the presence of a vacuum or in air at a temperature of from about 25° C. to about 200° C., and, in embodiments at about 70° C., for a period of from about 2 hours to about 48 hours, and in embodiments, for about 24 hours, thereby resulting in the isolation of a shiny purple solid, which was identified as being Type I titanyl phthalocyanine by its X-ray powder diffraction trace.
In still another embodiment, a Type I titanyl phthalocyanine may be prepared by (1) reacting a DI3 with a titanium tetra alkoxide such as, for example, titanium tetrabutoxide at a temperature of about 195° C. for about two hours; (ii) filtering the contents of the reaction to obtain a resulting solid; (iii) washing the solid with dimethylformamide (DMF); (iv) washing with four percent ammonium hydroxide; (v) washing with deionized water; (vi) washing with methanol; (vii) reslurrying the washes and filtering; and (viii) drying at about 70° C. under vacuum to obtain a Type I titanyl phthalocyanine.
In a process embodiment for preparing a high sensitivity phthalocyanine in accordance with the present disclosure, a Type I titanyl phthalocyanine is dissolved in a suitable solvent. In embodiments, a Type I titanyl phthalocyanine is dissolved in a solvent comprising a trihaloacetic acid and an alkylene halide. The alkylene halide comprises, in embodiments, from about one to about six carbon atoms. An example of a suitable trihaloacetic acid includes, but is not limited to, trifluoroacetic acid. In one embodiment, the solvent for dissolving a Type I titanyl phthalocyanine comprises trifluoroacetic acid and methylene chloride. In embodiments, the trihaloacetic acid is present in an amount of from about one volume part to about 100 volume parts of the solvent, and the alkylene halide is present in an amount of from about one volume part to about 100 volume parts of the solvent. In one embodiment, the solvent comprises methylene chloride and trifluoroacetic acid in a volume-to-volume ratio of about 4 to 1. The Type I titanyl phthalocyanine is dissolved in the solvent by stirring for an effective period of time, such as, for example, for about 30 seconds to about 24 hours, at room temperature. The Type I titanyl phthalocyanine is dissolved by, for example, stirring in the solvent for about one hour at room temperature (about 25° C.). The Type I titanyl phthalocyanine may be dissolved in the solvent in either air or in an inert atmosphere (argon or nitrogen).
In embodiments, the Type I titanyl phthalocyanine is converted to an intermediate titanyl phthalocyanine form prior to conversion to the high sensitivity titanyl phthalocyanine pigment. “Intermediate” in embodiments refers, for example, that the Type Y titanyl phthalocyanine is a separate form prepared in the process prior to obtaining the final desired Type V titanyl phthalocyanine product. For example, to obtain the intermediate form, which is designated as a Type Y titanyl phthalocyanine, the dissolved Type I titanyl phthalocyanine is added to a quenching system comprising an alkyl alcohol, alkyl including, for example, carbon chain lengths of from about 1 to about 12 carbon atoms, and alkylene halides, such as an alkylene chloride. Adding the dissolved Type I titanyl phthalocyanine to the quenching system or quenching mixture causes the Type Y titanyl phthalocyanine to precipitate. Materials suitable as the alkyl alcohol component of the quenching system include, but are not limited to, methanol, ethanol, propanol, butanol, and the like. In embodiments, the alkylene chloride component of the quenching system comprises from about one to about six carbon atoms. In embodiments, the quenching system comprises methanol and methylene chloride. The quenching system comprises an alkyl alcohol to alkylene chloride ratio of from about 1/4 to about 4/1 (v/v). In other embodiments, the ratio of alkyl alcohol to alkylene chloride is from about 1/1 to about 3/1 (v/v). In an embodiment, the quenching system comprises methanol and methylene chloride in a ratio of about 1/1 (v/v). In another embodiment, the quenching system comprises methanol and methylene chloride in a ratio of about 3/1 (v/v). In embodiments, the dissolved Type I titanyl phthalocyanine is added to the quenching system at a rate of from about 1 milliliter/minute to about 100 milliliters/minute, and the quenching system is maintained at a temperature of from about 0° C. to about −25° C. during quenching. In a further embodiment, the quenching system is maintained at a temperature of from about 0° C. to about −25° C. for a period of from about 0.1 hour to about 8 hours after addition of the dissolved Type I titanyl phthalocyanine solution.
Following precipitation of the Type Y titanyl phthalocyanine, the precipitates may be washed with any suitable solution, including, for example, methanol, cold deionized water, hot deionized water, and the like. Generally, washing the precipitate will also be accompanied by filtration. A wet cake containing Type Y titanyl phthalocyanine and water is obtained with water content varying from about 30 to about 70 weight percent of the wet cake.
The Type V titanyl phthalocyanine is obtained by treating the obtained intermediate Type Y titanyl phthalocyanine with a halo, such as, for example, monochlorobenzene. The Type Y titanyl phthalocyanine wet cake may be redispersed in monochlorobenzene, filtered and oven-dried at a temperature of from about 60° C. to about 85° C. to provide the resultant Type V titanyl phthalocyanine. The monochlorobenzene treatment may occur over a period of about 1 hour to about 24 hours. In one embodiment, the monochlorobenzene treatment is accomplished for a period of about five hours.
A titanyl phthalocyanine obtained in accordance with processes of the present disclosure, which is designated as a Type V titanyl phthalocyanine, exhibits, for example, an X-ray powder diffraction spectrum distinguishable from other known titanyl phthalocyanine polymorphs. In embodiments, the Type V titanyl phthalocyanine obtained exhibits an X-ray diffraction spectrum having four characteristic peaks at 9.0°, 9.6°, 24.0°, and 27.2°. A titanyl phthalocyanine prepared by a process in accordance with the present disclosure may have a particle size diameter of from about 10 nanometers to about 500 nanometers. Particle size may be controlled or affected by the quenching rate when adding the dissolved Type I titanyl phthalocyanine to the quenching system and the composition of the quenching system.
Generally, the thickness of the photogenerating layer depends on a number of factors, including the thicknesses of the. other layers and the amount of photogenerating material contained in the photogenerating layer. Accordingly, this layer can be of a thickness of, for example, from about 0.05 micron to about 30 microns, or to about 10 microns, and more specifically, from about 0.25 micron to about 2 microns when, for example, the photogenerating compositions are present in an amount of from about 30 to about 75 percent by volume. The maximum thickness of this layer in embodiments is dependent primarily upon factors, such as photosensitivity, electrical properties and mechanical considerations. The photogenerating layer binder resin includes those polymers as disclosed in U.S. Pat. No. 3,121,006, the disclosure of which is totally incorporated herein by reference, and is present in various suitable amounts, for example from about 1 to about 50 weight percent, and more specifically, from about 1 to about 10 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, alcohols, aromatic hydrocarbons, halogenated aliphatic hydrocarbons, ethers, amines, amides, esters, and the like. Specific 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 the photogenerating layer may contain in addition to the high sensitivity titanyl phthalocyanine other known photogenerating pigments like metal phthalocyanines, metal free phthalocyanines, alkylhydroxyl gallium phthalocyanines, hydroxygallium phthalocyanines, chlorogallium phthalocyanines, perylenes, especially bis(benzimidazo)perylene, titanyl phthalocyanines, and the like, and more specifically, vanadyl phthalocyanines, Type V hydroxygallium phthalocyanines, and inorganic components such as selenium, selenium alloys, and trigonal selenium.
Generally, in embodiments the photoconductor is comprised of the above photogenerating layer deposited on a supporting substrate, and which layer can be situated between the at least one charge transport layer and the substrate.
The thickness of the substrate layer depends on many factors, including economical considerations, electrical characteristics, and the like, thus this layer may be of 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 microns to about 300 microns, or from about 100 microns to about 150 microns.
The substrate may be opaque or substantially transparent and may comprise any suitable material inclusive of known materials with suitable mechanical properties. Accordingly, the substrate may comprise a layer of an electrically nonconductive or conductive material such as an inorganic or an organic composition. As electrically nonconducting materials, there may be employed various resins known for this purpose including polyesters, polycarbonates, polyamides, polyurethanes, and the like, which are flexible as thin webs. An electrically conducting substrate may be any suitable metal of, for example, aluminum, nickel, steel, copper, and the like, or a polymeric material, as described above, filled with an electrically conducting substance, such as carbon, metallic powder, and the like, or an organic electrically conducting material. The electrically insulating or conductive substrate may be in the form of an endless flexible belt, a web, a rigid cylinder, a sheet, and the like. The thickness of the substrate layer depends on numerous factors, including strength desired and economical considerations. For a drum, as disclosed in a copending application referenced herein, 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, for example about 250 micrometers, or of a minimum thickness of less than 50 micrometers, provided there are no adverse effects on the final electrophotographic device.
Illustrative examples of substrates are as illustrated herein, and can 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®.
Various resins can be used as electrically nonconducting materials, including, but not limited to, polyesters, polycarbonates, polyamides, polyurethanes, and the like. Examples of suitable substrate materials include, but are not limited to, a commercially available biaxially oriented polyester known as MYLAR™, available from E.I. DuPont de Nemours & Company, MELINEX™, available from ICI Americas Inc., or HOSTAPHAN™, available from American Hoechst Corporation. Other materials of which the substrate may be comprised include polymeric materials, such as polyvinyl fluoride, available as TEDLAR™ from E.I. DuPont de Nemours & Company, polyethylene and polypropylene, available as MARLEX™ from Phillips Petroleum Company, polyphenylene sulfide, RYTON™, available from Phillips Petroleum Company, and polyimides, available as KAPTONTM from E.I. DuPont de Nemours & Company. The photoreceptor can also be coated on an insulating plastic drum, provided a conducting ground plane has previously been coated on its surface, as described above. Such substrates can either be seamed or seamless.
When a conductive substrate is employed, any suitable conductive material can be selected. For example, the conductive material can include, but is not limited to, metal flakes, powders or fibers, such as aluminum, titanium, nickel, chromium, brass, gold, stainless steel, carbon black, graphite, or the like, in a binder resin including metal oxides, sulfides, silicides, quaternary ammonium salt compositions, conductive polymers, such as polyacetylene or its pyrolysis, and molecular doped products, charge transfer complexes, polyphenyl silane, and molecular doped products from polyphenyl silane. A conducting plastic drum can be used, as well as the preferred conducting metal drum made from a material such as aluminum.
Aryl amines selected for the charge, especially hole transporting layers, which generally are of a thickness of from about 5 microns to about 75 microns, and more specifically, of a thickness of from about 10 microns to about 40 microns, include molecules of the following formula
wherein X is at least one of alkyl, alkoxy, aryl, or a halogen, and especially those substitutents selected from the group consisting of Cl and CH3; 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 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 substitutent is a chloro substitutent; 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.
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 the illustrated 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.
Examples of charge transporting molecules for the plurality of charge transport layers, at least one charge transport layer, such as the first and second charge transport layer, are as indicated herein and include, for example, known hole transport components; aryl amines such as N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine, N,N′-diphenyl-N,N-bis(4-methylphenyl)-1,1′-biphenyl-4,4′-diamine, N,N′-diphenyl-N,N-bis(2-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, optionally mixtures thereof, and the like. In embodiments, to minimize or avoid cycle-up in equipment, such as printers, with high throughput, it is sometimes desirable that the charge transport layer be substantially free (less than about two percent) of di or triamino-triphenyl methane. The electrically active small molecule charge transporting compounds are dissolved or molecularly dispersed in electrically inactive polymeric film forming materials. 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 specifically includes N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine, N,N′-diphenyl-N,N-bis(4-methylphenyl)-1,1′-biphenyl-4,4′-diamine, N,N′-diphenyl-N,N-bis(2-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. 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.
The charge transport layer should be an insulator to the extent that the 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 maintained from about 2:1 to 200:1, and in some instances as great as 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, that is the photogenerating layer, and allows these holes to be transported through itself to selectively discharge a surface charge on the surface of the active layer.
The thickness of the continuous charge transport overcoat layer selected depends, for example, 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 micrometers. In embodiments, this thickness for each layer is from about 1 micrometer to about 5 micrometers. 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. Free carrier concentration in the overcoat increases the dark decay.
The overcoat layer or layers can comprise the same components as the charge transport layer wherein the weight ratio between the charge transporting small molecule, 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 the binder materials selected for the charge transport layers include components, such as those described in U.S. Pat. No. 3,121,006, the disclosure of which is totally incorporated herein by reference. Specific examples of polymer binder materials include polycarbonates, polyarylates, acrylate polymers, vinyl polymers, cellulose polymers, polyesters, polysiloxanes, polyamides, polyurethanes, poly(cyclo olefins), epoxies, and random or alternating copolymers thereof. In embodiments, electrically inactive binders are comprised of polycarbonate resins with, for example, a molecular weight of from about 20,000 to about 100,000, and more specifically, with a molecular weight Mw of from about 50,000 to about 100,000. Examples of polycarbonates are poly(4,4′-isopropylidene-diphenylene)carbonate (also referred to as bisphenol-A-polycarbonate, poly(4,4′-cyclohexylidinediphenylene)carbonate (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.
The optional hole blocking or undercoat layer for the imaging members of the present disclosure can contain a number of components, including known hole blocking components, such as amino silanes, doped metal oxides, TiSi, a metal oxide like titanium, chromium, zinc, tin, and the like; a mixture of phenolic compounds and a phenolic resin, or a mixture of two phenolic resins; and optionally a dopant such as SiO2. The phenolic compounds usually contain at least two phenol groups, such as bisphenol A (4,4′-isopropylidenediphenol), E (4,4′-ethylidenebisphenol), F (bis(4-hydroxyphenyl)methane), M (4,4′-(1,3-phenylenediisopropylidene)bisphenol), P (4,4′-(1,4-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 weight percent to about 80 weight percent, and more specifically, from about 55 weight percent to about 65 weight percent of suitable component like a metal oxide, such as TiO2, from about 20 weight percent to about 70 weight percent, and more specifically, from about 25 weight percent to about 50 weight percent of a phenolic resin; from about 2 weight percent to about 20 weight percent, and more specifically, from about 5 weight percent to about 15 weight percent of a phenolic compound preferably containing at least two phenolic groups, such as bisphenol S, and from about 2 weight percent to about 15 weight percent, and more specifically, from about 4 weight percent to about 10 weight percent of a plywood suppression dopant, such as SiO2. The hole blocking layer coating dispersion can, for example, be prepared as follows. The metal oxide/phenolic resin dispersion is first prepared by ball milling or dynomilling until the median particle size of the metal oxide in the dispersion is less than about 10 nanometers, for example from about 5 to about 9. To the above dispersion, a phenolic compound and dopant are added followed by mixing. The hole blocking layer coating dispersion can be applied by dip coating or web coating, and the layer can be thermally cured after coating. The hole blocking layer resulting is, for example, of a thickness of from about 0.01 micron to about 30 microns, and more specifically, from about 0.1 micron to about 8 microns. Examples of phenolic resins include formaldehyde polymers with phenol, p-tert-butylphenol, cresol, such as VARCUM® 29159 and 29101 (available from OxyChem Company), and DURITE® 97 (available from Borden Chemical), formaldehyde polymers with ammonia, cresol and phenol, such as VARCUM® 29112 (available from OxyChem Company), formaldehyde polymers with 4,4′-(1-methylethylidene)bisphenol, such as VARCUM™29108 and 29116 (available from OxyChem Company), formaldehyde polymers with cresol and phenol, such as VARCUM® 29457 (available from OxyChem Company), DURITE® SD-423A, SD-422A (available from Borden Chemical), or formaldehyde polymers with phenol and p-tert-butylphenol, such as DURITE® ESD 556C (available from Border Chemical).
The optional hole blocking layer may be applied to the substrate. Any suitable and conventional blocking layer capable of forming an electronic barrier to holes between the adjacent photoconductive layer (or electrophotographic imaging layer) and the underlying conductive surface of the substrate may be selected.
In embodiments, a suitable known adhesive layer, usually situated between the hole blocking layer and the photogenerating layer, can be selected for the photoconductor. Typical adhesive layer materials include, for example, polyesters, polyurethanes, and the like. The adhesive layer thickness can vary, and in embodiments is, for example, from about 0.05 micrometer (500 Angstroms) to about 0.3 micrometer (3,000 Angstroms). The adhesive layer can be deposited on the hole blocking layer by spraying, dip coating, roll coating, wire wound rod coating, gravure coating, Bird applicator coating, and the like. Drying of the deposited coating may be effected by, for example, oven drying, infrared radiation drying, air drying and the like.
As adhesive layer component examples, there can be selected various known substances inclusive of polyesters, copolyesters, polyamides, poly(vinyl butyral), poly(vinyl alcohol), polyurethane, and polyacrylonitrile. This layer is, for example, of a thickness of from about 0.001 micron to about 1 micron, or from about 0.1 to about 0.5 micron. Optionally, this layer may contain effective suitable amounts, for example from about 1 to about 10 weight percent, of conductive and nonconductive particles, such as zinc oxide, titanium dioxide, silicon nitride, carbon black, and the like, to provide, for example, in embodiments of the present disclosure further desirable electrical and optical properties.
Aspects of the present disclosure relate to a photoconductive imaging member comprised of a supporting substrate, a photogenerating layer thereover, and thereover the photogenerating layer at least one charge transport layer, such as from 2 to about 8 layers, from 2 to about 4 layers, one layer, two layers, and the like, and an overcoating charge transport layer; a photoconductive member with a photogenerating layer of a thickness of from about 1 to about 10 microns; 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, and thereover a layer comprised of a Type V titanyl phthalocyanine photogenerating pigment and a charge transport layer or layers, and thereover an overcoating charge transport layer; a member wherein the photogenerating layer contains the photogenerating pigment present in an amount of from about 5 to about 95 weight percent; a member wherein the thickness of the photogenerating layer is from about 0.1 to about 4 microns; a member wherein the photogenerating layer contains a polymer binder the same as or similar to the charge transport layer binder; a member wherein the photogenerating layer 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 Type V titanyl phthalocyanine that absorbs light of a wavelength of from about 370 to about 950 nanometers; an imaging member wherein the supporting substrate is comprised of a conductive substrate comprised of a metal; an imaging member wherein the conductive substrate is aluminum, aluminized polyethylene terephthalate or titanized polyethylene terephthalate; an imaging member wherein the photogenerating resinous binder is selected from the group consisting of polyesters, polyvinyl butyrals, polycarbonates, polystyrene-b-polyvinyl pyridine, and polyvinyl formals; a photoconductor wherein at least one or each of a plurality of the charge transport layers comprises hole transport molecules
wherein the X substitutent, which can be located in the para or meta positions, is selected from the group consisting of alkyl, alkoxy, substituted alkyl, substituted alkoxy, and halogen; 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 comprises
wherein X and Y are independently alkyl, alkoxy, aryl, substituted alkyl, substituted alkoxy, substituted aryl, a halogen such as fluoride, chloride, bromide or iodide, or mixtures thereof; an imaging member wherein alkyl and alkoxy contain from about 1 to about 12 carbon atoms; a photoconductive imaging member wherein for each charge transport layer there is selected in a suitable effective amount an aryl terphenyl amine selected from the group consisting of 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, other known terphenyls, and mixtures thereof; a photoconductive imaging member comprised of a supporting substrate, and thereover a layer comprised of titanyl phthalocyanine Type V photogenerating pigments, and a plurality of charge transport layers; 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; a member wherein the photogenerating layer is of a thickness of from about 0.1 to about 50 microns; a member wherein the photogenerating component amount is from about 20 weight percent to about 90 weight percent, and wherein the photogenerating pigment is optionally 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 1 to about 12 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 55 to about 95 percent by weight, and wherein the total of the layer components is about 100 percent; an 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; and a color imaging method 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.
In embodiments, there can be included in the photoconductor thiophosphates, especially dialkyldithiophosphates, like metal free or metal dialkyldithiophosphates, wherein metal includes, for example, zinc, molybdenum, lead, and antimony, and which thiophosphates are, more specifically, included in at least one of the charge transport layers, or optionally also or exclusively in the photogenerating layer, and wherein the metal dialkyldithiophosphates are encompassed by or of the following formulas/structures
wherein R1, R2, R3, R4, R5 and R6 each independently represent a hydrogen atom; alkyl with, for example, from 1 to about 20 carbon atoms; cycloalkyl with, for example, from 6 to about 26 carbon atoms; aryl, alkylaryl or arylalkyl groups with from about 6 to about 50 carbon atoms; a hydrocarbyl group containing, for example, from about 3 to about 20 carbon atoms, and containing an ester, ether, alcohol or carboxyl group; and an alkyl group which may be straight chain or branched with, for example, from about 2 to about 18 carbon atoms, or from about 4 to about 8 carbon atoms. Examples of alkyl and alkoxy groups include ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, ethylhexyl, and the like, and mixtures thereof, and the corresponding alkoxides.
Specific examples of metal dialkyldithiophosphates include molybdenum di(2-ethylhexyl)dithiophosphate, zinc diethyldithiophosphate, antimony diamyldithiophosphate, and the like. Commercial zinc dialkyldithiophosphates include ELCO® 102, 103, 108, 114, 119, and 121, available from Elco Corporation, Cleveland, Ohio. In embodiments, the thiophosphates are comprised of a certain amount of petroleum distillates, mineral oils, such as ValPar500™, available from Valero Energy Corporation, San Antonio, Tex.; and commercial molybdenum dialkyldithiophosphates include MOLYVAN® L (molybdenum di(2-ethylhexyl)phosphorodithioate), available from R.T. Vanderbilt Company, Inc., Norwalk, Conn. Commercial antimony dialkyldithiophosphates include VANLUBE® 622 and 648 (antimony dialkylphosphorodithioate), available from R.T. Vanderbilt Company, Inc., Norwalk, Conn.
Various effective amounts of the thiophosphates, which function primarily as permitting excellent photoconductor electricals, although in theory there could be interactions between the thiophosphates and other components, can be added to each charge transport layer and/or to the photogenerating layer components, such as, for example, from about 0.01 to about 30 weight percent, from about 0.1 to about 10 weight percent, or from about 0.5 to about 5 weight percent in the charge transport layer or layers; and from about 0.1 to about 40 weight percent, from about 1 to about 20 weight percent, or from about 5 to about 15 weight percent in the photogenerating layer.
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 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 layer is from about 0 to about 20, from about 1 to about 10, or from about 3 to about 8 weight percent.
Primarily for purposes of brevity, the examples of each of the substitutents and each of the components/compounds/molecules, polymers, (components) for each of the substrate, charge transport, resin binders, hole blocking, and adhesive layers, specifically disclosed herein are not intended to be exhaustive. Thus, a number of components, polymers, formulas, structures, and R group or substitutent examples and carbon chain lengths not specifically disclosed or claimed are intended to be encompassed by the present disclosure and claims. For example, these substitutents include suitable known groups, such as aliphatic and aromatic hydrocarbons with various carbon chain lengths, and which hydrocarbons can be substituted with a number of suitable known groups and mixtures thereof. Also, the carbon chain lengths are intended to include all numbers between those disclosed or claimed or envisioned, thus from 1 to about 20 carbon atoms, and from 6 to about 42 carbon atoms includes 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 up to 42, 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. These Examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. Also, parts and percentages are by weight unless otherwise indicated. Comparative Examples and data are also provided.
A Type I titanyl phthalocyanine (TiOPc) was prepared as follows. To a 300 milliliter three-necked flask fitted with mechanical stirrer, condenser and thermometer maintained under an argon atmosphere were added 3.6 grams (0.025 mole) of 1,3-diiminoisoindoline, 9.6 grams (0.075 mole) of o-phthalonitrile, 75 milliliters (80 weight percent) of N-methylpyrrolidone and 7.11 grams (0.025 mole) of titanium tetrapropoxide (all obtained from Aldrich Chemical Company except phthalonitrile which was obtained from BASF). The resulting mixture (20 weight percent of solids) was stirred and warmed to reflux (about 198° C.) for 2 hours. The resultant black suspension was cooled to about 150° C., and then was filtered by suction through a 350 milliliter, M-porosity sintered glass funnel, which had been preheated with boiling dimethyl formamide (DMF). The solid Type I TiOPc product resulting washed with two 150 milliliter portions of boiling DMF and the filtrate, initially black, became a light blue-green color. The solid was slurried in the funnel with 150 milliliters of boiling DMF and the suspension was filtered. The resulting solid washed in the funnel with 150 milliliters of DMF at 25° C., and then with 50 milliliters of methanol. The resultant shiny purple solid was dried at 70° C. overnight to yield 10.9 grams (76 percent) of pigment, which was identified as Type I TiOPc on the basis of its X-ray powder diffraction trace. Elemental analysis of the product indicated C, 66.54; H, 2.60; N, 20.31; and Ash (TiO2), 13.76. TiOPc requires (theory): C, 66.67; H, 2.80; N, 19.44; and Ash, 13.86.
A Type I titanyl phthalocyanine can also be prepared in 1-chloronaphthalene as follows. A 250 milliliter three-necked flask fitted with mechanical stirrer, condenser and thermometer maintained under an atmosphere of argon was charged with 1,3-diiminoisoindolene (14.5 grams), titanium tetrabutoxide (8.5 grams), and 75 milliliters of 1-chloronaphthalene (CINp). The mixture was stirred and warmed. At 140° C. the mixture turned dark green and began to reflux. At this time the vapor (which was identified as n-butanol by gas chromatography) was allowed to escape to the atmosphere until the reflux temperature reached 200° C. The reaction was maintained at this temperature for two hours then was cooled to 150° C. The product was filtered through a 150 milliliter M-porosity sintered glass funnel, which was preheated to approximately 150° C. with boiling DMF, and then washed thoroughly with three portions of 150 milliliters of boiling DMF, followed by washing with three portions of 150 milliliters of DMF at room temperature, and then three portions of 50 milliliters of methanol, thus providing 10.3 grams (72 percent yield) of a shiny purple pigment, which was identified as Type I TiOPc by X-ray powder diffraction (XRPD).
Fifty grams of TiOPc Type I were dissolved in 300 milliliters of a trifluoroacetic acid/methylene chloride (1/4, volume/volume) mixture for 1 hour in a 500 milliliter Erlenmeyer flask with magnetic stirrer. At the same time, 2,600 milliliters of methanol/methylene chloride (1/1, volume/volume) quenching mixture was cooled with a dry ice bath for 1 hour in a 3,000 milliliter beaker with magnetic stirrer, and the final temperature of the mixture was about −25° C. The resulting TiOPc solution was transferred to a 500 milliliter addition funnel with a pressure-equalization arm, and added into the cold quenching mixture over a period of 30 minutes. The mixture obtained was then allowed to stir for an additional 30 minutes, and subsequently hose-vacuum filtered through a 2,000 milliliter Buchner funnel with fibrous glass frit of 4 to 8 μm in porosity. The pigment resulting was then well mixed with 1,500 milliliters of methanol in the funnel, and vacuum filtered. The pigment was then well mixed with 1,000 milliliters of hot water (>90° C.), and vacuum filtered in the funnel four times. The pigment was then well mixed with 1,500 milliliters of cold water, and vacuum filtered in the funnel. The final water filtrate was measured for conductivity, which was below 10 μS. The resulting wet cake contained approximately 50 weight percent of water. A small portion of the wet cake was dried at 65° C. under vacuum and a blue pigment was obtained. A representative XRPD of this pigment after quenching with methanol/methylene chloride was identified by XRPD as Type Y titanyl phthalocyanine.
The remaining portion of the wet cake was redispersed in 700 grams of monochlorobenzene (MCB) in a 1,000 milliliter bottle and rolled for an hour. The dispersion was vacuum filtered through a 2,000 milliliter Buchner funnel with a fibrous glass frit of 4 to 8 μm in porosity over a period of two hours. The pigment was then well mixed with 1,500 milliliters of methanol and filtered in the funnel twice. The final pigment was vacuum dried at 60° C. to 65° C. for two days. Approximately 45 grams of the pigment were obtained. The XRPD of the resulting pigment after the MCB conversion is designated as a Type V titanyl phthalocyanine. The Type V had a X-ray diffraction pattern having characteristic diffraction peaks at a Bragg angle of 2Θ±0.2° at about 9.0°, 9.6°, 24.0°, and 27.2°.
Preparation of Type Iv Titanyl Phthalocyanine
Five hundred grams of TiOPc Type I were dissolved in 5 liters of a 1/4(volume/volume) mixture of trifluoroacetic acid and methylene chloride over a period of approximately 15 minutes. A 1/1 (v/v) methanol/water mixture (50 liters), which had been cooled overnight to about 0° C., was divided into three equal portions and placed in three plastic 5 gallon pails. The dissolved pigment solution was also divided into three equal portions and added dropwise to the chilled methanol/water over a period of 1 hour. The precipitated solid clung to the sides of the pails, allowing for removal of the solvents by simple decantation. The solid was then redispersed in methanol (50 liters), and filtered through a Buchner Funnel (600 centimeter diameter) fitted with a glass fiber filter paper, and then washed with approximately 50 liters of hot water (60° C. to 80° C.). The wet cake was then redispersed in monochlorobenzene (50 liters) and filtered as before. The washed pigment obtained was then oven dried at 70° C. overnight (about 18 to 20 hours) to afford 455 grams (91 percent yield) of a powdery blue pigment, which was identified as Type IV titanyl phthalocyanine by XRPD. The Type IV had an X-ray diffraction pattern having characteristic diffraction peaks at a Bragg angle 2Θ±0.2° at about 9.6°, 24.0°, and 27.2°
The Type V TiOPc pigment prepared by a process according to the present disclosure generated four characteristic peaks at 9.0°, 9.6° 24.0°, and 27.2°, and is thus distinguishable from the Type IV TiOPc pigment.
TEM and SEM micrographs of a Type V TiOPc prepared by the process of Example Hi, and an SEM micrograph of a Type IV TiOPc prepared according to Comparative Example I were generated. The Type V TiOPc of Example II exhibited a surface area of about 40 m2/grams as compared to 20 m2/grams for the TiOPc of Comparative Example 1.
An imaging member was prepared by providing a 0.02 micrometer thick titanium layer coated on a biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000) having a thickness of 3.5 mils, and applying thereon, with a gravure applicator, a solution containing 50 grams of 3-amino-propyltriethoxysilane, 41.2 grams of water, 15 grams of acetic acid, 684.8 grams of denatured alcohol and 200 grams of heptane. This layer was then dried for about 5 minutes at 135° C. in the forced air dryer of the coater. The resulting blocking layer had a dry thickness of 500 Angstroms. An adhesive layer was then prepared by applying a wet coating over the blocking layer, using a gravure applicator, and which adhesive contains 0.2 percent by weight based on the total weight of the solution of the copolyester adhesive (ARDEL™ D100 available from Toyota Hsutsu Inc.) in a 60:30:10 volume ratio mixture of tetrahydrofuran/monochlorobenzene/methylene chloride. The adhesive layer was then dried for about 5 minutes at 135° C. in the forced air dryer of the coater. The resulting adhesive layer had a dry thickness of 200 Angstroms.
A photogenerating layer dispersion was prepared by introducing 0.45 gram of the known polycarbonate LUPILON 200™ (PCZ-200) or Polycarbonate Z, weight average molecular weight of 20,000, available from Mitsubishi Gas Chemical Corporation, and 50 milliliters of tetrahydrofuran into a 4 ounce glass bottle. To this solution were added 2.4 grams of hydroxygallium phthalocyanine (HOGaPc, Type V) and 300 grams of ⅛ inch (3.2 millimeter) diameter stainless steel shot. This mixture was then placed on a ball mill for 8 hours. Subsequently, 2.25 grams of PCZ-200 was dissolved in 46.1 grams of tetrahydrofuran, and added to the hydroxygallium 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 a Bird applicator to form a photogenerating layer having a wet thickness of 0.25 mil. A strip about 10 millimeters wide along one edge of the substrate web bearing the blocking layer and the adhesive layer was deliberately left uncoated by any of the photogenerating layer material to facilitate adequate electrical contact by the ground strip layer that was applied later. The photogenerating layer was dried at 120° C. for 1 minute in a forced air oven to form a dry photogenerating layer having a thickness of 0.4 micrometer.
This 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 0.4:0.6 N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine and MAKROLON 5705®, a known polycarbonate resin having a molecular weight average of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G. The resulting mixture was then dissolved in methylene chloride to form a solution containing 15 percent by weight solids. This solution was applied on the photogenerating layer to form a coating of the bottom layer 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 overcoated with a top layer. The charge transport layer solution of the top layer was prepared as described above for the bottom layer. This solution was applied on the bottom layer of the charge transport layer to form a coating that upon drying (120° C. for 1 minute) had a thickness of 14.5 microns. During this coating process, the humidity was equal to or less than 15 percent.
An imaging member is prepared by repeating the process of Comparative Example 2 except that the photogenerating layer dispersion was prepared by milling 1.65 grams of the known polycarbonate LUPILON™ 200 (PCZ-200) or Polycarbonate Z, weight average molecular weight of 20,000, available from Mitsubishi Gas Chemical Corporation, 1.65 grams of titanyl phthalocyanine Type V of Example II, 56.7 grams of monochlorobenzene (MCB), and 150 grams of Glen Mills glass beads (1 to 1.25 millimeters in diameter) together via attritor for 1.5 hours. The resulting dispersion was, thereafter, applied to the above adhesive interface with a Bird applicator to form a photogenerating layer having a wet thickness of 0.25 mil. A strip about 10 millimeters wide along one edge of the substrate web bearing the blocking layer, and the adhesive layer was deliberately left uncoated by any of the photogenerating layer material to facilitate adequate electrical contact by the ground strip layer that was applied later. The photogenerating layer was dried at 120° C. for 1 minute in a forced air oven to form a dry photogenerating layer having a thickness of 0.4 micrometer.
An imaging member is prepared by repeating the process of Example III except that to the photogenerating layer dispersion of Example III are added 0.165 grams of zinc dialkyldithiophosphate (ZDDP ELCO® 103, wherein alkyl is a mixture of primary and secondary propyl, butyl and pentyl), commercially available from Elco Corporation.
An imaging member is prepared by repeating the process of Example III except that (1) the top layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 0.4:0.6:0.1 N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, MAKROLON 5705®, a polycarbonate resin having a molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and IRGANOX® 1010, tetrakis methylene(3,5-di-tert-butyl-4-hydroxy hydrocinnamate), commercially available from Ciba Specialty Chemical. The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids. (2)
Further, to the photogenerating layer dispersion of Example III are added 0.495 grams of zinc dialkyldithiophosphate (ZDDP ELCO® 103), commercially available from Elco Corporation.
An imaging member is prepared by repeating the process of Example III except that the bottom layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 0.4:0.6:0.005 N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, MAKROLON 5705®, a polycarbonate resin having a molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and zinc dialkyldithiophosphate (ZDDP ELCO® 102, wherein alkyl is a mixture of primary butyl and octyl), commercially available from Elco Corporation. The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids.
An imaging member is prepared by repeating the process of Example III except that the top layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 0.4:0.6:0.1:0.01 N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, MAKROLON 5705®, a polycarbonate resin having a molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, IRGANOX® 1010, commercially available from Ciba Specialty Chemical, and ZDDP ELCO® 103, commercially available from Elco Corporation. The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids.
An imaging member is prepared by repeating the process of Example III except that (1) the top layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 0.4:0.6:0.1 N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, MAKROLON 5705®, a polycarbonate resin having a molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and IRGANOX® 1010, commercially available from Ciba Specialty Chemical. The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids. (2) The bottom layer of the charge transport layer is prepared by introducing into an amber glass bottle in a weight ratio of 0.4:0.6:0.01 N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, MAKROLON 5705®, a polycarbonate resin having a molecular weight of from about 50,000 to about 100,000, commercially available from Farbenfabriken Bayer A.G, and zinc dialkyldithiophosphate (ZDDP ELCO® 102), commercially available from Elco Corporation. The resulting mixture is dissolved in methylene chloride to form a solution containing 15 percent by weight solids. (3) Further, to the photogenerating layer dispersion of Example III are added 0.495 grams of zinc dialkyldithiophosphate (ZDDP ELCO® 103), commercially available from Elco Corporation.
The above prepared photoreceptor devices are 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 is incrementally increased with cycling to produce a series of photoinduced discharge characteristic curves from which the photosensitivity and surface potentials at various exposure intensities are measured. Additional electrical characteristics are obtained by a series of charge-erase cycles with incrementing surface potential to generate several voltage versus charge density curves. The scanner is equipped with a scorotron set to a constant voltage charging at various surface potentials. The devices are tested at surface potentials of 400 volts with the exposure light intensity incrementally increased by means of regulating a series of neutral density filters; the exposure light source is a 780 nanometer light emitting diode. The xerographic simulation is completed in an environmentally controlled light tight chamber at ambient conditions (40 percent relative humidity and 22° C.). The devices are also cycled to 10,000 cycles electrically with charge-discharge-erase. Fourteen photoinduced discharge characteristic (PIDC) curves are generated, one for each of the above prepared photoconductors at both cycle=1 and cycle=10,000. The high sensitivity TiOPc (Type V) device (Example III) exhibits higher sensitivity by, for example, 10 to 15 percent than that of HOGaPc (Type V) device (Comparative Example 2).
In embodiments, there is disclosed a number of improved characteristics for the photoconductive members as determined by the generation of known PIDC curves, such as minimization or prevention of Vr (residual potential) cycle up by the physical doping of the thiophosphate like dialkyldithiophosphates in the charge transport layer, or photogenerating layer, or both layers. Incorporation of zinc dialkyldithiophosphate in the high sensitivity TiOPc (Type V) photogenerating layer (Examples IV and V), the bottom charge transport layer (Example VI), the top charge transport layer (Example VII), or both the charge transport layer and the high sensitivity TiOPc (Type V) photogenerating layer (Example VIII) further increases the sensitivity, lowers the residual potential, and eliminates the residual potential cycle up.
In embodiments, incorporation of the thiophosphate into charge transport layer, photogenerating layer, or both layers reduces ghosting.
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.
