Patent Grant
7897310
U.S. application Ser. No. 11/961,462, U.S. Publication No. 20090162765, filed Dec. 20, 2007, entitled Ketal Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the at least one charge transport layer contains at least one ketal.
U.S. application Ser No. 11/961,506, U.S. Publication No. 20090162768, filed Dec. 20, 2007, entitled Aminoketone Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the at least one charge transport layer contains at least one aminoketone.
U.S. application Ser. No. 11/961,549, U.S. Publication No. 20090162766, filed Dec. 20, 2007, entitled Photoconductors Containing Ketal Overcoats, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and an overcoat layer in contact with and contiguous to the charge transport layer, and which overcoat is comprised of a crosslinked polymeric network, an overcoat charge transport component, and at least one ketal.
U.S. application Ser. No. 11/964,561, U.S. Publication No. 20090162764, filed Dec. 20, 2007, entitled Nitrogen Heterocyclics Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and a triazine.
U.S. application Ser. No. 11/961,566, U.S. Publication No. 20090162767, filed Dec. 20, 2007, entitled Benzophenone Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the charge transport layer contains a benzophenone.
U.S. application Ser. No. 11/831,440, U.S. Publication No. 20090035673, filed Jul. 31, 2007 by Jin Wu, entitled Iron Containing Hole Blocking Layer Containing Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a substrate; an undercoat layer thereover wherein the undercoat layer comprises a metal oxide, and an iron containing compound; a photogenerating layer; and at least one charge transport layer.
U.S. application Ser. No. 11/869,258, U.S. Publication No. 20090092912, filed Oct. 9, 2007 by Jin Wu et al., entitled Imidazolium Salt Containing Charge Transport Layer Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and where at least one charge transport layer contains at least one imidazolium salt.
U.S. application Ser. No. 11/869,252, U.S. Publication No. 20090092911, filed Oct. 9, 2007 by Jin Wu et al., entitled Additive Containing Charge Transport Layer Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and an ammonium salt additive or dopant.
U.S. application Ser. No. 11/869,231, U.S. Publication No. 20090092913, filed Oct. 9, 2007 by Jin Wu et al., entitled Additive Containing Photogenerating Layer Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains at least one of an ammonium salt and an imidazolium salt.
U.S. application Ser. No. 11/800,129, U.S. Publication 20080274419, filed May 4, 2007 by Liang-Bih Lin et al., entitled Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a bis(pyridyl)alkylene.
U.S. application Ser. No. 11/800,108, now U.S. Pat. No. 7,662,526, filed May 4, 2007 by Liang-Bih Lin et al., entitled Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the charge transport layer contains a benzoimidazole.
U.S. application Ser. No. 11/869,269, now U.S. Pat. No. 7,709,169, filed Oct. 9, 2007 by Jin Wu, entitled Charge Trapping Releaser Containing Charge Transport Layer Photoconductors, the disclosure of which is totally incorporated herein by reference, discloses a photoconductor comprised of a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the at least one charge transport layer contains at least one charge trapping releaser.
U.S. application Ser. No. 11/848,428, U.S. Publication No. 20090061337, filed Aug. 31, 2007, the disclosure of which is totally incorporated herein by reference, illustrates a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a triazine.
U.S. application Ser. No. 11/848,417, U.S. Publication 20090061336, filed Aug. 31, 2007, the disclosure of which is totally incorporated herein by reference, illustrates a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a light stabilizer.
U.S. application Ser. No. 11/848,439, now U.S. Pat. No. 7,670,738, filed Aug. 31, 2007, the disclosure of which is totally incorporated herein by reference, illustrates a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a boron compound.
U.S. application Ser. No. 11/848,448, now U.S. Pat. No. 7,785,758, filed Aug. 31, 2007, the disclosure of which is totally incorporated herein by reference, illustrates a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a triazole.
U.S. application Ser. No. 11/848,454, U.S. Publication No. 20090061340, filed Aug. 31, 2007, the disclosure of which is totally incorporated herein by reference, illustrates a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the photogenerating layer contains a hydroxyalkoxy benzophenone.
In U.S. application Ser. No. 11/472,765, now U.S. Pat. No. 7,553,593, filed Jun. 22, 2006, and U.S. application Ser. No. 11/472,766, now U.S. Pat. No. 7,485,398, filed Jun. 22, 2006, the disclosures of which are totally incorporated herein by reference, there is disclosed, for example, photoconductors comprising a photogenerating layer and a charge transport layer, 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 a monohalobenzene.
High photosensitivity titanyl phthalocyanines are illustrated in copending U.S. application Ser. No. 10/992,500, U.S. Publication No. 20060105254, the disclosures of which are totally incorporated herein by reference, which, for example, discloses a process for the preparation of a Type V titanyl phthalocyanine, comprising providing a Type I titanyl phthalocyanine; dissolving the Type I titanyl phthalocyanine in a solution comprising a trihaloacetic acid and an alkylene halide like methylene chloride; adding the resulting mixture comprising the dissolved Type I titanyl phthalocyanine to a solution comprising an alcohol and an alkylene halide thereby precipitating a Type Y titanyl phthalocyanine; and treating the Type Y titanyl phthalocyanine with monochlorobenzene to yield a Type V titanyl phthalocyanine.
A number of the components of the above cross referenced applications, such as the supporting substrates, resin binders, antioxidants, charge transport components, photogenerating pigments like hydroxygallium phthalocyanines, and titanyl phthalocyanines, high photosensitivity titanyl phthalocyanines, such as Type V, hole blocking layer components, adhesive layers, and the like, may be selected for the photoconductor and imaging members of the present disclosure in embodiments thereof.
This disclosure is generally directed to layered imaging members, photoreceptors, photoconductors, and the like. More specifically, the present disclosure is directed to multilayered drum, or flexible, belt imaging members, or devices comprised of a supporting medium like a substrate, a photogenerating layer, and a charge transport layer, including at least one or a plurality of charge transport layers, and wherein at least one is, for example, from 1 to about 7, from 1 to about 3, and one, and more specifically a first charge transport layer and a second charge transport layer, and wherein the charge transport layer includes a component that results in photoconductors with, it is believed, a number of advantages, such as in embodiments, desirable light shock reductions; the minimization or substantial elimination of undesirable ghosting on developed images, such as xerographic images, including improved ghosting at various relative humidities; excellent cyclic and stable electrical properties; acceptable imaging depletion by, for example, generating free radicals which neutralize excess charge, and dark decay characteristics; minimal charge deficient spots (CDS); and compatibility with the photogenerating and charge transport resin binders. Light shock or light fatigue of photoconductors usually causes dark bands in the resulting xerographic prints from the light exposed photoconductor area at time zero, while the photoconductors disclosed herein in embodiments minimize or avoid this disadvantage in that, for example, the light shock resistant photoconductors do not usually print undesirable dark bands even when the photoconductor is exposed to light like office light sources.
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 toner image to a suitable image receiving substrate, and permanently affixing the image thereto. In those environments wherein the photoconductor is to be used in a printing mode, the imaging method involves the same operation with the exception that exposure can be accomplished with a laser device or image bar. More specifically, the flexible photoconductor belts disclosed herein can be selected for the Xerox Corporation iGEN® machines that generate with some versions over 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 color xerographic applications, particularly high-speed color copying and printing processes.
There is illustrated in U.S. Pat. No. 7,037,631 a photoconductive imaging member comprised of a supporting substrate, a hole blocking layer thereover, a crosslinked photogenerating layer and a charge transport layer, and wherein the photogenerating layer is comprised of a photogenerating component, and a vinyl chloride, allyl glycidyl ether, hydroxy containing polymer.
There is illustrated in U.S. Pat. No. 6,913,863, the disclosure of which is totally incorporated herein by reference, a photoconductive imaging member comprised of a hole blocking layer, a photogenerating layer, and a charge transport layer, and wherein the hole blocking layer is comprised of a metal oxide; and a mixture of a phenolic compound and a phenolic resin wherein the phenolic compound contains at least two phenolic groups.
Layered photoresponsive imaging members have been described in numerous U.S. patents, such as U.S. Pat. No. 4,265,990 wherein there is illustrated an imaging member comprised of a photogenerating layer, and an aryl amine hole transport layer. Examples of disclosed photogenerating layer components include trigonal selenium, metal phthalocyanines, vanadyl phthalocyanines, and metal free phthalocyanines.
In U.S. Pat. No. 4,921,769, there are illustrated photoconductive imaging members with blocking layers of certain polyurethanes.
Illustrated in U.S. Pat. No. 5,521,306, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of Type V hydroxygallium phthalocyanine comprising the in situ formation of an alkoxy-bridged gallium phthalocyanine dimer, hydrolyzing the dimer to hydroxygallium phthalocyanine, and subsequently converting the hydroxygallium phthalocyanine product to Type V hydroxygallium phthalocyanine.
Illustrated in U.S. Pat. No. 5,482,811, the disclosure of which is totally incorporated herein by reference, is a process for the preparation of hydroxygallium phthalocyanine photogenerating pigments which comprises hydrolyzing a gallium phthalocyanine precursor pigment by dissolving the hydroxygallium phthalocyanine in a strong acid, and then reprecipitating the resulting dissolved pigment in basic aqueous media; removing any ionic species formed by washing with water, concentrating the resulting aqueous slurry comprised of water and hydroxygallium phthalocyanine to a wet cake; removing water from said slurry by azeotropic distillation with an organic solvent, and subjecting said resulting pigment slurry to mixing with the addition of a second solvent to cause the formation of said hydroxygallium phthalocyanine polymorphs.
Also, in U.S. Pat. No. 5,473,064, the disclosure of which is totally incorporated herein by reference, there is illustrated a process for the preparation of photogenerating pigments of hydroxygallium phthalocyanine Type V essentially free of chlorine, whereby a pigment precursor Type I chlorogallium phthalocyanine is prepared by reaction of gallium chloride in a solvent, such as N-methylpyrrolidone, hydrolyzing said pigment precursor chlorogallium phthalocyanine Type I by standard methods, for example acid pasting, subsequently treating the resulting hydrolyzed pigment hydroxygallium phthalocyanine Type I with a solvent, such as N,N-dimethylformamide, present in an amount of from about 1 volume part 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 millimeter to 5 millimeters in diameter, at room temperature, about 25° C., for a period of from about 12 hours to about 1 week, and preferably about 24 hours.
In U.S. Pat. No. 4,587,189, the disclosure of which is totally incorporated herein by reference, there is illustrated a layered imaging member with, for example, a perylene, pigment photogenerating component and an aryl amine component, such as N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine dispersed in a polycarbonate binder as a hole transport layer.
Kanemitsu and Funada (J. Phys. D: Appl. Phys. 24, 1991, 1409-1415) have apparently suggested that light-induced fatigue of the photoconductor is a consequence of the build-up of the negative charges caused by electron trapping in the photogenerating layer and the positive charges caused by hole trapping at the photogenerating layer charge transport layer interface. The photoconductors illustrated herein in embodiments, and with an additive, such as a triazine, and those additives illustrated in the appropriate copending applications filed concurrently herewith, in the charge transport layer results in reduced light shock characteristics as compared to a similar photoconductor with no charge transport layer (CTL) additive as the additive is believed to absorb the UV portion of the white light and generate active species such as free radicals that can interact with or neutralize those light (usually visible light) generated charges within the photoconductor.
The appropriate components, such as the supporting substrates, the photogenerating layer components, the charge transport layer components, and the like of the above-recited patents, may be selected for the photoconductors of the present disclosure in embodiments thereof.
Aspects of the present disclosure relate to a photoconductor comprising a supporting substrate, a photogenerating layer, and at least one charge transport layer comprised of at least one charge transport component, and wherein the at least one charge transport layer contains at least one phosphine oxide; a photoconductor comprised in sequence of an optional supporting substrate, a photogenerating layer, and a charge transport layer; and wherein the charge transport layer contains a phosphine oxide component present in an amount of from about 0.01 to about 20 weight percent; and a photoconductor comprising a supporting substrate, a photogenerating layer, a hole transport layer; and wherein the hole transport layer has incorporated therein a phosphine oxide encompassed by
wherein R1, R2, and R3 are each independently at least one of hydrogen, alkyl, and aryl.
Phosphine oxide examples present in the charge transport layer or layers in various suitable amounts, such as from about 0.001 to about 20, from about 0.01 to about 10, from about 0.1 to about 5 weight percent based on the charge transport layer components of the charge transport component, the resin binder, optional known additives, include acyl phosphines readily available as photoinitiators used in UV curing.
Acyl phosphine oxide examples include mono acyl phosphine oxides (MAPO) or bis acyl phosphine oxides (BAPO) represented, for example, by the following formulas/structures
wherein each R substituent is hydrogen, alkyl, aryl, substituted derivatives thereof, and the like. Alkyl includes those known substituents with from about 1 to about 25 carbon atoms, and aryl includes those known substituents with, for example, from about 6 to about 42 carbon atoms.
Phosphine oxide specific examples include phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide (IRGACURE® 819), diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (DAROCUR® TPO, ESACURE® TPO, FIRSTCURE® HMPP and LUCIRIN® TPO), phenyl (2,4,6-trimethylbenzoyl)-phosphinate (LUCIRIN® TPO-L), respectively represented by the following formulas/structures
The thickness of the photoconductor substrate layer depends on various factors, including economical considerations, desired electrical characteristics, adequate flexibility, and the like, thus this layer may be of substantial thickness, for example over 3,000 microns, such as from about 1,000 to about 2,000 microns, from about 500 to about 1,000 microns, or from about 300 to about 700 microns (“about” throughout includes all values in between the values recited), or of a minimum thickness. In embodiments, the thickness of this layer is from about 75 microns to about 300 microns, or from about 100 to about 150 microns. In embodiments, the photoconductor can be free of a substrate, for example a layer usually in contact with the substrate can be increased in thickness. For a photoconductor drum, the substrate or supporting medium may be of a substantial thickness of, for example, up to several centimeters or of a minimum thickness of less than a millimeter. Similarly, a flexible belt may be of a substantial thickness of, for example, about 250 micrometers, or of a minimum thickness of less than about 50 micrometers, provided there are no adverse effects on the final electrophotographic device.
Also, the photoconductor may in embodiments include a blocking layer, an adhesive layer, a top overcoating protective layer, and an anticurl backing layer.
The photoconductor substrate may be opaque, substantially opaque, or substantially transparent, and may comprise any suitable material that, for example, permits the photoconductor layers to be supported. Accordingly, the substrate may comprise a number of known layers, and more specifically, the substrate can be comprised of an electrically nonconductive or conductive material such as an inorganic or an organic composition. As electrically nonconducting materials, there may be selected 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 comprise any suitable metal of, for example, aluminum, nickel, steel, copper, and the like, or a polymeric material 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.
In embodiments where the substrate layer is to be rendered conductive, the surface thereof may be rendered electrically conductive by an electrically conductive coating. The conductive coating may vary in thickness depending upon the optical transparency, degree of flexibility desired, and economic factors, and in embodiments this layer can be of a thickness of from about 0.05 micron to about 5 microns.
Illustrative examples of substrates are as illustrated herein, and more specifically, supporting substrate layers selected for the photoconductors of the present disclosure comprise a layer of insulating material including inorganic or organic polymeric materials, such as MYLAR® a commercially available polymer, MYLAR® containing titanium, a layer of an organic or inorganic material having a semiconductive surface layer, such as indium tin oxide, or aluminum arranged thereon, or a conductive material inclusive of aluminum, chromium, nickel, brass, or the like. The substrate may be flexible, seamless, or rigid, and may have a number of many different configurations, such as for example, a plate, a cylindrical drum, a scroll, an endless flexible belt, and the like. In embodiments, the substrate is in the form of a seamless flexible belt. In some situations, it may be desirable to coat on the back of the substrate, particularly when the substrate is a flexible organic polymeric material, an anticurl layer, such as for example polycarbonate materials commercially available as MAKROLON®.
Generally, the photogenerating layer can contain known photogenerating pigments, such as metal phthalocyanines, metal free phthalocyanines, and more specifically, alkylhydroxyl gallium phthalocyanines, hydroxygallium phthalocyanines, chlorogallium phthalocyanines, perylenes, especially bis(benzimidazo)perylene, titanyl phthalocyanines, and the like, and yet more specifically, vanadyl phthalocyanines, Type V hydroxygallium phthalocyanines, and inorganic components such as selenium, selenium alloys, and trigonal selenium. The photogenerating pigment can be dispersed in a resin binder similar to the resin binders selected for the charge transport layer, or alternatively no resin binder need be present. Generally, the thickness of the photogenerating layer depends on a number of factors, including the thicknesses of the other layers and the amount of photogenerating material contained in the photogenerating layer. Accordingly, this layer can be of a thickness of, for example, from about 0.05 micron to about 10 microns, and more specifically, from about 0.25 micron to about 2 microns when, for example, the photogenerating compositions are present in an amount of from about 30 to about 75 percent by volume.
In embodiments, the photogenerating component or pigment is present in a resinous binder in various amounts, inclusive of 100 percent by weight based on the weight of the photogenerating components that are present. Generally, however, from about 5 percent by volume to about 95 percent by volume of the photogenerating pigment is dispersed in about 95 percent by volume to about 5 percent by volume of the resinous binder, or from about 20 percent by volume to about 30 percent by volume of the photogenerating pigment is dispersed in about 70 percent by volume to about 80 percent by volume of the resinous binder composition. In one embodiment, about 90 percent by volume of the photogenerating pigment is dispersed in about 10 percent by volume of the resinous binder composition, and which resin may be selected from a number of known polymers, such as poly(vinyl butyral), poly(vinyl carbazole), polyesters, polycarbonates, poly(vinyl chloride), polyacrylates and methacrylates, copolymers of vinyl chloride and vinyl acetate, phenolic resins, polyurethanes, poly(vinyl alcohol), polyacrylonitrile, polystyrene, and the like. It is desirable to select a coating solvent that does not substantially disturb or adversely affect the other previously coated layers of the device. Examples of coating solvents for the photogenerating layer are ketones, alcohols, aromatic hydrocarbons, halogenated aliphatic hydrocarbons, ethers, amines, amides, esters, and the like. Specific solvent examples are cyclohexanone, acetone, methyl ethyl ketone, methanol, ethanol, butanol, amyl alcohol, toluene, xylene, chlorobenzene, carbon tetrachloride, chloroform, methylene chloride, trichloroethylene, tetrahydrofuran, dioxane, diethyl ether, dimethyl formamide, dimethyl acetamide, butyl acetate, ethyl acetate, methoxyethyl acetate, and the like.
In embodiments, examples of polymeric binder materials that can be selected as the matrix for the photogenerating layer components are known and include thermoplastic and thermosetting resins, such as polycarbonates, polyesters, polyamides, polyurethanes, polystyrenes, polyarylethers, polyarylsulfones, polybutadienes, polysulfones, polyethersulfones, polyethylenes, polypropylenes, polyimides, polymethylpentenes, poly(phenylene sulfides), poly(vinyl acetate), polysiloxanes, polyacrylates, polyvinyl acetals, polyamides, polyimides, amino resins, phenylene oxide resins, terephthalic acid resins, phenoxy resins, epoxy resins, phenolic resins, polystyrene, and acrylonitrile copolymers, poly(vinyl chloride), vinyl chloride and vinyl acetate copolymers, acrylate copolymers, alkyd resins, cellulosic film formers, poly(amideimide), styrenebutadiene copolymers, vinylidene chloride-vinyl chloride copolymers, vinyl acetate-vinylidene chloride copolymers, styrene-alkyd resins, poly(vinyl carbazole), and the like. These polymers may be block, random, or alternating copolymers.
Various suitable and conventional known processes may be used to mix, and thereafter apply the photogenerating layer coating mixture like spraying, dip coating, roll coating, wire wound rod coating, vacuum sublimation, and the like. For some applications, the photogenerating layer may be fabricated in a dot or line pattern. Removal of the solvent of a solvent-coated layer may be effected by any known conventional techniques such as oven drying, infrared radiation drying, air drying, and the like.
The final dry thickness of the photogenerating layer is as illustrated herein, and can be, for example, from about 0.01 to about 30 microns after being dried at, for example, about 40° C. to about 150° C. for about 15 to about 90 minutes. More specifically, a photogenerating layer of a thickness, for example, of from about 0.1 to about 30, or from about 0.5 to about 2 microns can be applied to or deposited on the substrate, on other surfaces in between the substrate and the charge transport layer, and the like. A charge blocking layer or hole blocking layer may optionally be applied to the electrically conductive surface prior to the application of a photogenerating layer. When desired, an adhesive layer may be included between the charge blocking or hole blocking layer or interfacial layer and the photogenerating layer. Usually, the photogenerating layer is applied onto the blocking layer and a charge transport layer or plurality of charge transport layers are formed on the photogenerating layer. This structure may have the photogenerating layer on top of or below the charge transport layer.
In embodiments, a suitable known adhesive layer can be included in the photoconductor. Typical adhesive layer materials include, for example, polyesters, polyurethanes, and the like. The adhesive layer thickness can vary and in embodiments is, for example, from about 0.05 micrometer (500 Angstroms) to about 0.3 micrometer (3,000 Angstroms). The adhesive layer can be deposited on the hole blocking layer by spraying, dip coating, roll coating, wire wound rod coating, gravure coating, Bird applicator coating, and the like. Drying of the deposited coating may be effected by, for example, oven drying, infrared radiation drying, air drying, and the like.
As an adhesive layer usually in contact with or situated between the hole blocking layer and the photogenerating layer, there can be selected various known substances inclusive of copolyesters, polyamides, poly(vinyl butyral), poly(vinyl alcohol), polyurethane, and polyacrylonitrile. This layer is, for example, of a thickness of from about 0.001 micron to about 1 micron, or from about 0.1 to about 0.5 micron. Optionally, this layer may contain effective suitable amounts, for example from about 1 to about 10 weight percent, of conductive and nonconductive particles, such as zinc oxide, titanium dioxide, silicon nitride, carbon black, and the like, to provide, for example, in embodiments of the present disclosure further desirable electrical and optical properties.
The optional hole blocking or undercoat layer or layers for the imaging members of the present disclosure can contain a number of components including known hole blocking components, such as amino silanes, doped metal oxides, a metal oxide like titanium, chromium, zinc, tin and the like; a mixture of phenolic compounds and a phenolic resin, or a mixture of two phenolic resins, and optionally a dopant such as SiO2. The phenolic compounds usually contain at least two phenol groups, such as bisphenol A (4,4′-isopropylidenediphenol), E (4,4′-ethylidenebisphenol), F (bis(4-hydroxyphenyl)methane), M (4,4′-(1,3-phenylenediisopropylidene)bisphenol), P (4,4′-(1,4-phenylene diisopropylidene)bisphenol), S (4,4′-sulfonyldiphenol), and Z (4,4′-cyclohexylidenebisphenol); hexafluorobisphenol A (4,4′-(hexafluoro isopropylidene)diphenol), resorcinol, hydroxyquinone, catechin, and the like.
The hole blocking layer can be, for example, comprised of from about 20 weight percent to about 80 weight percent, and more specifically, from about 55 weight percent to about 65 weight percent of a suitable component like a metal oxide, such as TiO2, from about 20 weight percent to about 70 weight percent, and more specifically, from about 25 weight percent to about 50 weight percent of a phenolic resin; from about 2 weight percent to about 20 weight percent, and more specifically, from about 5 weight percent to about 15 weight percent of a phenolic compound preferably containing at least two phenolic groups, such as bisphenol S, and from about 2 weight percent to about 15 weight percent, and more specifically, from about 4 weight percent to about 10 weight percent of a plywood suppression dopant, such as SiO2. The hole blocking layer coating dispersion can, for example, be prepared as follows. The metal oxide/phenolic resin dispersion is first prepared by ball milling or dynomilling until the median particle size of the metal oxide in the dispersion is less than about 10 nanometers, for example from about 5 to about 9. To the above dispersion are added a phenolic compound and dopant followed by mixing. The hole blocking layer coating dispersion can be applied by dip coating or web coating, and the layer can be thermally cured after coating. The hole blocking layer resulting is, for example, of a thickness of from about 0.01 micron to about 30 microns, and more specifically, from about 0.1 micron to about 8 microns. Examples of phenolic resins include formaldehyde polymers with phenol, p-tert-butylphenol, cresol, such as VARCUM™ 29159 and 29101 (available from OxyChem Company), and DURITE™ 97 (available from Borden Chemical); formaldehyde polymers with ammonia, cresol and phenol, such as VARCUM™ 29112 (available from OxyChem Company); formaldehyde polymers with 4,4′-(1-methylethylidene)bisphenol, such as VARCUM™ 29108 and 29116 (available from OxyChem Company); formaldehyde polymers with cresol and phenol, such as VARCUM™ 29457 (available from OxyChem Company), DURITE™ SD-423A, SD-422A (available from Borden Chemical); or formaldehyde polymers with phenol and p-tert-butylphenol, such as DURITE™ ESD 556C (available from Border Chemical).
The hole blocking layer may be applied to the substrate. Any suitable and conventional blocking layer capable of forming an electronic barrier to holes between the adjacent photoconductive layer (or electrophotographic imaging layer) and the underlying conductive surface of substrate may be selected.
A number of charge transport compounds can be included in the charge transport layer, which layer generally is of a thickness of from about 5 microns to about 75 microns, and more specifically, of a thickness of from about 10 microns to about 40 microns. Examples of charge transport components are aryl amines of the following formulas/structures
wherein X is a suitable hydrocarbon like alkyl, alkoxy, aryl, and derivatives thereof; a halogen, or mixtures thereof, and especially those substituents selected from the group consisting of Cl and CH3; and molecules of the following formulas
wherein X, Y and Z are independently alkyl, alkoxy, aryl, a halogen, or mixtures thereof, and wherein at least one of Y and Z are present.
Alkyl and alkoxy contain, for example, from 1 to about 25 carbon atoms, and more specifically, from 1 to about 12 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 that can be selected for the charge transport layer include N,N′-diphenyl-N,N′-bis(alkylphenyl)-1,1-biphenyl-4,4′-diamine wherein alkyl is selected from the group consisting of methyl, ethyl, propyl, butyl, hexyl, and the like; N,N′-diphenyl-N,N′-bis(halophenyl)-1,1′-biphenyl-4,4′-diamine wherein the halo substituent is a chloro substituent; N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-m-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-o-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2-ethyl-6-methylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4′-diamine, N,N′-diphenyl-N,N′-bis(3-chlorophenyl)-[p-terphenyl]-4,4″-diamine, and the like. Other known charge transport layer molecules can be selected, reference for example, U.S. Pat. Nos. 4,921,773 and 4,464,450, the disclosures of which are totally incorporated herein by reference.
Examples of 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. 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 percent 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 layer may comprise charge transporting small molecules dissolved or molecularly dispersed in a film forming electrically inert polymer such as a polycarbonate. In embodiments, “dissolved” refers, for example, to forming a solution in which the small molecule is dissolved in the polymer to form a homogeneous phase; and “molecularly dispersed in embodiments” refers, for example, to charge transporting molecules dispersed in the polymer, the small molecules being dispersed in the polymer on a molecular scale. Various charge transporting or electrically active small molecules may be selected for the charge transport layer or layers. In embodiments, charge transport refers, for example, to charge transporting molecules as a monomer that allows the free charge generated in the photogenerating layer to be transported across the transport layer.
Examples of hole transporting molecules present in the charge transport layer, or layers, for example, in an amount of from about 50 to about 75 weight percent include, for example, pyrazolines such as 1-phenyl-3-(4′-diethylamino styryl)-5-(4″-diethylamino phenyl)pyrazoline; aryl amines such as N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine, 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; 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 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 10 to about 70 micrometers, 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 usually 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 about 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 through itself to selectively discharge a surface charge on the surface of the active 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. An optional overcoating may be applied over the charge transport layer to provide abrasion protection.
Examples of components or materials optionally incorporated into the charge transport layers or at least one charge transport layer to, for example, enable excellent lateral charge migration (LCM) resistance include hindered phenolic antioxidants, such as tetrakis methylene(3,5-di-tert-butyl-4-hydroxy hydrocinnamate) methane (IRGANOX™ 1010, available from Ciba Specialty Chemical), butylated hydroxytoluene (BHT), and other hindered phenolic antioxidants including SUMILIZER™ BHT-R, MDP-S, BBM-S, WX-R, 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 layers is from about 0 to about 20, from about 1 to about 10, or from about 3 to about 8 weight percent.
The present disclosure in embodiments thereof relates to a photoconductive member comprised of a supporting substrate, a photogenerating layer, a light shock reducing additive containing 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, and at least one transport layer each of a thickness of from about 5 to about 100 microns; 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; a member wherein the binder is present in an amount of from about 50 to about 90 percent by weight, and wherein the total of all layer components is about 100 percent; a member wherein the photogenerating component is a hydroxygallium phthalocyanine that absorbs light of a wavelength of from about 370 to about 950 nanometers; an imaging member wherein the supporting substrate is comprised of a conductive substrate comprised of a metal; an imaging member wherein the conductive substrate is aluminum, aluminized polyethylene terephthalate, or titanized polyethylene terephthalate; a photoconductor wherein the photogenerating resinous binder is selected from the group consisting of polyesters, polyvinyl butyrals, polycarbonates, polystyrene-b-polyvinyl pyridine, and polyvinyl formals; an imaging member wherein the photogenerating pigment is a metal free phthalocyanine; a photoconductor wherein each of the charge transport layers, especially a first and second charge transport layer, comprises
wherein X is selected from the group consisting of lower, that is with, for example, from 1 to about 8 carbon atoms, alkyl, alkoxy, aryl, and halogen; a photoconductor wherein each of, or at least one of the charge transport layers comprises
wherein X and Y are independently lower alkyl, lower alkoxy, phenyl, a halogen, or mixtures thereof, and wherein the photogenerating and charge transport layer resinous binder is selected from the group consisting of polycarbonates and polystyrene; a photoconductor wherein the photogenerating pigment present in the photogenerating layer is comprised of chlorogallium phthalocyanine, or Type V hydroxygallium phthalocyanine prepared by hydrolyzing a gallium phthalocyanine precursor by dissolving the hydroxygallium phthalocyanine in a strong acid, and then reprecipitating the resulting dissolved precursor in a basic aqueous media; removing any ionic species formed by washing with water; concentrating the resulting aqueous slurry comprised of water and hydroxygallium phthalocyanine to a wet cake; removing water from the wet cake by drying; and subjecting the resulting dry pigment to mixing with the addition of a second solvent to cause the formation of the hydroxygallium phthalocyanine; an imaging member wherein the Type V hydroxygallium phthalocyanine has major peaks, as measured with an X-ray diffractometer, at Bragg angles (2 theta+/−0.2°) 7.4, 9.8, 12.4, 16.2, 17.6, 18.4, 21.9, 23.9, 25.0, 28.1 degrees, and the highest peak at 7.4 degrees; a method of imaging which comprises generating an electrostatic latent image on the photoconductor developing the latent image, and transferring the developed electrostatic image to a suitable substrate; a method of imaging wherein the imaging member is exposed to light of a wavelength of from about 370 to about 950 nanometers; a member wherein the photogenerating layer is of a thickness of from about 0.1 to about 50 microns; a member wherein the photogenerating pigment is dispersed in from about 1 weight percent to about 80 weight percent of a polymer binder; a member wherein the binder is present in an amount of from about 50 to about 90 percent by weight, and wherein the total of the layer components is about 100 percent; a photoconductor wherein the photogenerating component is Type V hydroxygallium phthalocyanine, or chlorogallium phthalocyanine, and the charge transport layer contains a hole transport of N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-p-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-m-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-di-o-tolyl-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(4-isopropylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2-ethyl-6-methylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-bis(4-butylphenyl)-N,N′-bis-(2,5-dimethylphenyl)-[p-terphenyl]-4,4″-diamine, N,N′-diphenyl-N,N′-bis(3-chlorophenyl)-[p-terphenyl]-4,4″-diamine molecules, and wherein the hole transport resinous binder is selected from the group consisting of polycarbonates and polystyrene; an imaging member wherein the photogenerating layer contains a metal free phthalocyanine; a photoconductive imaging member comprised of a supporting substrate, a doped photogenerating layer, a hole transport layer, and in embodiments wherein a plurality of charge transport layers are selected, such as for example, from two to about ten, and more specifically two, may be selected; and a photoconductive imaging member comprised of an optional supporting substrate, a photogenerating layer, and a first, second, and third charge transport layer.
The following Examples are provided.
A dispersion of a hole blocking layer was prepared by milling 18 grams of TiO2 (MT-150W, manufactured by Tayca Co., Japan), 24 grams of a phenolic resin (VARCUM® 29159, OxyChem. Co.) at a solid weight ratio of about 60 to about 40 in a solvent of about 50 to about 50 in weight of xylene and 1-butanol, and a total solid content of about 52 percent in an Attritor mill with about 0.4 to about 0.6 millimeter size ZrO2 beads for 6.5 hours, and then filtering with a 20 micron Nylon filter. To the resulting dispersion was then added methyl ethyl ketone in a solvent mixture of xylene, 1-butanol at a weight ratio of 47.5:47.5:5 (xylene:butanol:ketone). A 30 millimeter aluminum drum substrate was coated using known coating techniques with the above-formed dispersion. After drying at 160° C. for 20 minutes, a hole blocking layer of TiO2 in the phenolic resin (TiO2/phenolic resin=60/40) about 10 microns in thickness was obtained.
A photogenerating layer at a thickness of about 0.2 micron comprising chlorogallium phthalocyanine (Type B) was disposed on the above hole blocking layer or undercoat layer at a thickness of about 10 microns. The photogenerating layer coating dispersion was prepared as follows. 2.7 Grams of chlorogallium phthalocyanine (ClGaPc) Type B pigment was mixed with 2.3 grams of polymeric binder (carboxyl-modified vinyl copolymer, VMCH, Dow Chemical Company), 15 grams of n-butyl acetate and 30 grams of xylene. The mixture was milled in an Attritor mill with about 200 grams of 1 millimeter Hi-Bea borosilicate glass beads for about 3 hours. The dispersion was filtered through a 20 micron nylon cloth filter, and the solid content of the dispersion was diluted to about 6 weight percent.
Subsequently, a 32 micron charge transport layer was coated on top of the photogenerating layer from a dispersion prepared from N,N′-diphenyl-N,N-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine (5.38 grams), a film forming polymer binder PCZ 400 [poly(4,4′-dihydroxy-diphenyl-1-1-cyclohexane, Mw=40,000)] available from Mitsubishi Gas Chemical Company, Ltd. (7.13 grams), and PTFE POLYFLON™ L-2 microparticle (1 gram), available from Daikin Industries, dissolved/dispersed in a solvent mixture of 20 grams of tetrahydrofuran (THF) and 6.7 grams of toluene via a CAVIPRO™ 300 nanomizer (Five Star Technology, Cleveland, Ohio). The charge transport layer was dried at about 120° C. for about 40 minutes.
There was prepared a photoconductor with a biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000) having a thickness of 3.5 mils, and thereover, a 0.02 micron thick titanium layer was coated on the biaxially oriented polyethylene naphthalate substrate (KALEDEX™ 2000). Subsequently, there was applied thereon, with a gravure applicator or an extrusion coater, a hole blocking layer solution containing 50 grams of 3-aminopropyl triethoxysilane (γ-APS), 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 1 minute at 120° C. in a forced air dryer. The resulting hole blocking layer had a dry thickness of 500 Angstroms. An adhesive layer was then deposited by applying a wet coating over the blocking layer, using a gravure applicator or an extrusion coater, and which adhesive contained 0.2 percent by weight based on the total weight of the solution of the copolyester adhesive (ARDEL D100™ available from Toyota Hsutsu Inc.) in a 60:30:10 volume ratio mixture of tetrahydrofuran/monochlorobenzene/methylene chloride. The adhesive layer was then dried for about 1 minute at 120° 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) weight average molecular weight of 20,000, available from Mitsubishi Gas Chemical Corporation, and 50 milliliters of tetrahydrofuran into a 4 ounce glass bottle. To this solution were added 2.4 grams of hydroxygallium phthalocyanine (Type V) and 300 grams of ⅛ inch (3.2 millimeters) diameter stainless steel shot. This mixture was then placed on a ball mill for 8 hours. Subsequently, 2.25 grams of PCZ-200 were dissolved in 46.1 grams of tetrahydrofuran, and added to the 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 from 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 of that was applied later. The photogenerating layer was dried at 120° C. for 1 minute in a forced air oven to form a dry photogenerating layer having a thickness of 0.4 micron.
The resulting photoconductor web was then coated with a dual charge transport layer. The first charge transport layer was prepared by introducing into an amber glass bottle in a weight ratio of 50/50, N,N′-bis(methylphenyl)-1,1-biphenyl-4,4′-diamine (TBD) and poly(4,4′-isopropylidene diphenyl)carbonate, a known bisphenol A polycarbonate having a Mw molecular weight average of about 120,000, commercially available from Farbenfabriken Bayer A.G. as MAKROLON® 5705. The resulting mixture was then dissolved in methylene chloride to form a solution containing 15.6 percent by weight solids. This solution was applied on the photogenerating layer to form the charge transport layer coating that upon drying (120° C. for 1 minute) had a thickness of 16.5 microns. During this coating process, the humidity was equal to or less than 30 percent, for example 25 percent.
The above first pass charge transport layer (CTL) was then overcoated with a second top charge transport layer in a second pass. The charge transport layer solution of the top layer was prepared introducing into an amber glass bottle in a weight ratio of 35/65, N,N′-bis(methylphenyl)-1,1-biphenyl-4,4′-diamine (TBD) and poly(4,4′-isopropylidene diphenyl)carbonate, a known bisphenol A polycarbonate having a Mw molecular weight average of about 120,000, commercially available from Farbenfabriken Bayer A.G. as MAKROLON® 5705. The resulting mixture was then dissolved in methylene chloride to form a solution containing 15.6 percent by weight solids. This solution was applied, using a 2 mil Bird bar, 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 16.5 microns. During this coating process the humidity was equal to or less than 15 percent. The total two-layer CTL thickness was 33 microns.
A photoconductor was prepared by repeating the process of Comparative Example 1 except that there was included in the charge transport layer 0.1 percent by weight of the additive phenyl bis(2,4,6-trimethyl benzoyl)phosphine oxide (available as IRGACURE® 819 from Ciba Specialty Chemicals, Basel, Switzerland), and subsequently, the charge transport layer dispersion components were mixed for about 10 hours before coating this layer on the photogenerating layer.
A photoconductor is prepared by repeating the process of Comparative Example 2 except that there is included in the first charge transport layer 2.5 percent by weight of the additive phenyl bis(2,4,6-trimethyl benzoyl) phosphine oxide (IRGACURE® 819, Ciba Specialty Chemicals, Basel, Switzerland), and subsequently, the charge transport layer solution components are mixed for at about 10 hours before coating this solution/dispersion on the photogenerating layer.
A photoconductor is prepared by repeating the process of Example I except that there is included in the charge transport layer in place of 0.1 weight percent of the phosphine oxide recited, 0.2 percent by weight of the additive diphenyl (2,4,6-trimethylbenzoyl)-phosphine oxide (ESACURE® TPO, LAMBERTI Chemical Specialties, Gallarate, Italy), and the charge transport layer dispersion is then allowed to mix for at least 8 hours, such as about 12 hours.
A photoconductor is prepared by repeating the process of Example I except that there is included in the charge transport layer in place of 0.1 weight percent of the phosphine oxide recited, 0.8 percent by weight of the additive phenyl (2,4,6-trimethylbenzoyl)-phosphinate (LUCIRIN® TPO-L, BASF, Ludwigshafen, Germany), and the charge transport layer dispersion is then allowed to mix for at least 8 hours, such as about 12 hours.
The above prepared photoconductors of Comparative Example 1 and Example I were tested in a scanner set to obtain photoinduced discharge cycles, sequenced at one charge-erase cycle followed by one charge-expose-erase cycle, wherein the light intensity was incrementally increased with cycling to produce a series of photoinduced discharge characteristic curves from which the photosensitivity and surface potentials at various exposure intensities were measured. Additional electrical characteristics were obtained by a series of charge-erase cycles with incrementing surface potential to generate several voltages 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 700 volts with the exposure light intensity incrementally increased by means of regulating a series of neutral density filters; and the exposure light source was a 780 nanometer light emitting diode. The xerographic simulation was completed in an environmentally controlled light tight chamber at ambient conditions (40 percent relative humidity and 22° C.).
The photoconductors of Comparative Examples 1 and Example I exhibited substantially identical PIDCs. Thus, incorporation of the additive into the charge transport layer did not adversely affect the electrical properties of the Example I photoconductor.
An in-house light shock test was performed for the above-prepared photoconductor devices (Comparative Example 1 and Example I). The top half of (50 percent) of each of the above-prepared photoconductors was exposed under office light for 120 minutes, and the PIDCs were measured immediately after light exposure. As comparison, the bottom half of the photoconductor was shielded by black paper during the above light exposure, and the PIDCs of the bottom halves were also measured. The light shock results are summarized in Table 1.
V(2.8 ergs/cm2), which is the surface potential of the photoconductors when the exposure was 2.8 ergs/cm2, was used to characterize the photoconductors. When the above drum photoconductors were exposed to a white light source, (3,000 lux, or office light), V(2.8 ergs/cm2) was reduced quickly after exposure, for example 5 minutes after, and then the photoconductor tended to recover from this surface potential drop caused by the above white light source after a period of rest, for example 24 hours later.
The disclosed photoconductor device (Example I) exhibited a 28V decrease in V(2.8 ergs/cm2) whereas the controlled photoconductor of Comparative Example 1 exhibited a 54V decrease in V(2.8 ergs/cm2) after light exposure, which indicated that the Example I photoconductor was more light shock resistant with less drop in V(2.8 ergs/cm2) after light exposure.
Thus, incorporation of the phosphine oxide additive in the charge transport layer improved light shock resistance with the initial drop in V(2.8 ergs/cm2) being about one half of that of the Comparative Example 1 photoconductor with no additive in the charge transport layer.
For an ideal photoconductor, V(2.8 ergs/cm2) should usually remain unchanged whether the photoconductor is exposed to light or not.
Light shock, such as the photoconductors of Comparative Examples 1 and 2 usually causes dark bands in xerographic prints when the photoconductors are exposed to light at t=0 (time zero). The light shock resistant Example I photoconductor did not xerographically print dark bands even when the photoconductor was exposed to white light.
The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
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