Patent Application
20080032218
Aspects of the present disclosure relate to a member, like a photoconductor, comprising a substrate, an undercoat layer thereover comprised, for example, of a suitable binder polymer, such as a mixture of a polyol resin, and an aminoplast resin, a silanol, and a metal oxide; and at least one imaging layer formed on the undercoat layer; a photoconductor comprising a substrate, an undercoat layer thereover comprising a polyol resin, an aminoplast resin, a silanol component, and a metal oxide, a photogenerating layer and at least one charge transport layer; a photoconductor comprising a supporting substrate, a hole blocking layer thereover comprising a polyol resin, an aminoplast resin, a silanol, and a metal oxide, a photogenerating layer and a charge transport layer; a photoconductor wherein the photogenerating layer is situated between the charge transport layer and the substrate, and which layer contains a resin binder; and wherein a silanol is present in an amount of from about 0.1 to about 25 weight percent based on the total weight of the undercoat layer components; a photoreceptor having an undercoat layer which incorporates an additive that reduces, and substantially eliminates specific printing defects, such as background and CDS, in the resulting printed images; an electrophotographic imaging member which generally comprises at least a substrate layer, an undercoat layer, and an imaging layer with the undercoat layer being generally located between the substrate and the imaging layer, although additional layers may be present and located between these layers; an imaging member comprising a substrate, a layer thereover comprised of at least one polymeric resin, a silanol and a metal oxide, and at least one imaging layer formed on the undercoat layer; a photoconductor comprising a substrate, a layer thereover comprising a polyol resin, an aminoplast resin, at least one, such as for example from 1 to about 5, from 2 to about 4, and 1, silanol, and a metal oxide; and thereover a photogenerating layer and at least one, such as 1 to about 7, 1 to about 4, and more specifically 1, charge transport layer; and a photoconductor comprising in sequence a substrate; a hole blocking layer thereover comprised of a silanol, a polymeric resin and a metal oxide; a photogenerating layer; and a charge transport layer, and wherein the silanol is of the formulas/structures
and wherein R and R′ are independently a suitable hydrocarbon such as alkyl, alkoxy, aryl, substituted derivatives thereof wherein the substituents can, for example, be alkyl, alkoxy, aryl, cycloalkyl, halogen, and the like.
Examples of silanols selected in various suitable amounts, such as for example, from about 0.1 to about 40, from about 0.5 to about 20, or from 1 to about 10 weight percent, and which silanols can also be referred to as polyhedral oligomeric silsesquioxane (POSS) silanols include
wherein R and R′ are independently selected from the group comprised of a suitable hydrocarbon, such as alkyl, alkoxy, aryl, and substituted derivatives thereof and mixtures thereof, with, for example, from about 1 to about 25 carbon atoms for alkyl and alkoxy, and from 6 to about 36 carbon atoms for aryl like phenyl, methyl, vinyl, allyl, isobutyl, isooctyl, cyclopentyl, cyclohexyl, cyclohexenyl-3-ethyl, epoxycyclohexyl-4-ethyl-, fluorinated alkyl such as CF3CH2CH2—, and CF3(CF2)5CH2CH2-methacrylolpropyl, norborneylethyl, and the like.
POSS silanol examples wherein POSS refers to polyhedral oligomeric silsesquioxane silanols, include isobutyl-POSS cyclohexenyldimethylsilyldisilanol or isobutyl-polyhedral oligomeric silsesquioxane cyclohexenyldimethylsilyldisilanol (C38H84O12Si8), cyclopentyl-POSS dimethylphenyldisilanol (C43H76O12Si8), cyclohexyl-POSS dimethylvinyldisilanol (C46H88O12Si8), cyclopentyl-POSS dimethylvinyldisilanol (C39H74O12Si8), isobutyl-POSS dimethylvinyidisilanol (C32H74O12Si8), cyclopentyl-POSS disilanol (C40H74P13Si8), isobutyl-POSS disilanol (C32H74)13Si8), isobutyl-POSS epoxycyclohexyldisilanol (C38H84O13Si8), cyclopentyl-POSS fluoro(3)disilanol (C40H75F3O12Si8), cyclopentyl-POSS fluoro(13)disilanol (C45H75F13O12Si8), isobutyl-POSS fluoro(13)disilanol (C38H75F13O12Si8), cyclohexyl-POSS methacryldisilanol (C51H96O14Si8), cyclopentyl-POSS methacryldisilanol (C44H82O14Si8), isobutyl-POSS methacryldisilanol (C37H82O14Si8), cyclohexyl-POSS monosilanol (C42H78O13Si8), cyclopentyl-POSS monosilanol (Schwabinol, C35H64O13Si8), isobutyl-POSS monosilanol (C28H64O13Si8), cyclohexyl-POSS norbornenylethyldisilanol (C53H98O12Si8), cyclopentyl-POSS norbornenylethyldisi lanol (C46H84O12Si8), isobutyl-POSS norbornenylethyldisilanol (C39H84O12Si8), cyclohexyl-POSS TMS disilanol (C45H88O12Si8), isobutyl-POSS TMS disilanol (C31H74O12Si8), cyclohexyl-POSS trisilanol (C42H80O12Si7), cyclopentyl-POSS trisilanol (C35H66O12Si7), isobutyl-POSS trisilanol (C28H66O12Si7), isooctyl-POSS trisilanol (C56H122O12Si7), phenyl-POSS trisilanol (C42H38O12Si7), and the like, all commercially available from Hybrid Plastics, Fountain Valley, Calif.
A specific POSS silanol is a phenyl-POSS trisilanol; and a phenyl-polyhedral oligomeric silsesquioxane trisilanol of the following formula/structure
The POSS silanol can contain a suitable number of silicone atoms, such as for example, from about 7 to about 20 silicone atoms, or from about 7 to about 12 silicone atoms. The Mw of the POSS silanol is, for example, from about 700 to about 2,000, or from about 800 to about 1,300.
Silanol examples that can be selected in embodiments are free or substantially free of POSS. Examples of such silanols include dimethyl(thien-2-yl)silanol, tris(isopropoxy)silanol, tris(tert-butoxy)silanol, tris(tert-pentoxy)silanol, tril(o-tolyl)silanol, tris(1-naphthyl)silanol, tris(2,4,6-trimethylphenyl)silanol, tris(2-methoxyphenyl)silanol, tris(4-(dimethylamino)phenyl)silanol, tris(4-biphenylyl)silanol, tris(trimethylsilyl)silanol, dicyclohexyltetrasilanol (C12H26O5Si2), mixtures thereof, and the like.
A number of silanols selected for the members, devices, and photoconductors illustrated herein are stable primarily in view of the Si—OH substituents in that these substituents eliminate water to form siloxanes that is Si—O—Si linkages. While not to be limited by theory, it is believed that in view of the silanol hindered structure at the other three bonds attached to the silicone that they are stable for extended time periods, such as from at least one week to over one year.
Polyol resin examples selected for the UCL include an acrylic polyol resin, a styrene acrylic polyol resin, and a phenolic resin. Examples of acrylic polyol resins or acrylics are copolymers of derivatives of acrylic and methacrylic acid including acrylic and methacrylic esters and compounds containing nitrile and amide groups, and other optional monomers. Styrene acrylic polyol resins or styrene acrylics can be considered copolymers of styrene, derivatives of acrylic and methacrylic acid including acrylic and methacrylic esters, and compounds containing nitrile and amide groups, and other optional monomers. Specific examples of acrylic esters are n-alkyl acrylates such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl, tetradecyl, or hexadecyl acrylate; secondary and branched-chain alkyl acrylates such as isopropyl, isobutyl, sec-butyl, 2-ethylhexyl, or 2-ethylbutyl acrylate; olefinic acrylates such as allyl, 2-methylallyl, furfuryl, or 2-butenyl acrylate; aminoalkyl acrylates such as 2-(dimethylamino)ethyl, 2-(diethylamino)ethyl, 2-(dibutylamino)ethyl, or 3-(diethylamino)propyl acrylate; ether acrylates such as 2-methoxyethyl, 2-ethoxyethyl, tetrahydrofurfuryl, or 2-butoxyethyl acrylate; cycloalkyl acrylates such as cyclohexyl, 4-methylcyclohexyl, or 3,3,5-trimethylcyclohexyl acrylate; halogenated alkyl acrylates such as 2-bromoethyl, 2-chloroethyl, or 2,3-dibromopropyl acrylate; glycol acrylates and diacrylates such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, 1,5-pentanediol, triethylene glycol, dipropylene glycol, 2,5-hexanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, or 1,10-decanediol acrylate and diacrylate. Methacrylic ester examples include alkyl methacrylates such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-hexyl, n-octyl, isooctyl, 2-ethylhexyl, n-decyl, or tetradecyl methacrylate; unsaturated alkyl methacrylates such as vinyl, allyl, oleyl, or 2-propynyl methacrylate; cycloalkyl methacrylates such as cyclohexyl, 1-methylcyclohexyl, 3-vinylcyclohexyl, 3,3,5-trimethylcyclohexyl, bornyl, isobornyl, or cyclopenta-2,4-dienyl methacrylate; aryl methacrylates such as phenyl, benzyl, or nonylphenyl methacrylate; hydroxyalkyl methacrylates such as 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, or 3,4-dihydroxybutyl methacrylate; ether methacrylates such as methoxymethyl, ethoxymethyl, 2-ethoxyethoxymethyl, allyloxymethyl, benzyloxymethyl, cyclohexyloxymethyl, 1-ethoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, 1-methyl-(2-vinyloxy)ethyl, methoxymethoxyethyl, methoxyethoxyethyl, vinyloxyethoxyethyl, 1-butoxypropyl, 1-ethoxybutyl, tetrahydrofurfuryl, or furfuryl methacrylate; oxiranyl methacrylates such as glycidyl, 2,3-epoxybutyl, 3,4-epoxybutyl, 2,3-epoxycyclohexyl, or 10,11-epoxyundecyl methacrylate; aminoalkyl methacrylates such as 2-dimethylaminoethyl, 2-diethylaminoethyl, 2-t-octylaminoethyl, N,N-dibutylaminoethyl, 3-diethylaminopropyl, 7-amino-3,4-dimethyloctyl, N-methylformamidoethyl, or 2-ureidoethyl methacrylate; glycol dimethacrylates such as methylene, ethylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 2,5-dimethyl-1,6-hexanediol, 1,10-decanediol, diethylene glycol, or triethylene glycol dimethacrylate; trimethacrylates such as trimethylolpropane trimethacrylate; carbonyl-containing methacrylates such as carboxymethyl, 2-carboxyethyl, acetonyl, oxazolidinylethyl, N-(2-methacryloyloxyethyl)-2-pyrrolidinone, N-methacryloyl-2-pyrrolidinone, N-(metharyloyloxy)formamide, N-methacryloylmorpholine, or tris(2-methacryloxyethyl)amine methacrylate; other nitrogen-containing methacrylates such as 2-methacryloyloxyethylmethyl cyanamide, methacryloyloxyethyltrimethylammonium chloride, N-(methacryloyloxy-ethyl) diisobutylketimine, cyanomethyl, or 2-cyanoethyl methacrylate; halogenated alkyl methacrylates such as chloromethyl, 1,3-dichloro-2-propyl, 4-bromophenyl, 2-bromoethyl, 2,3-dibromopropyl, or 2-iodoethyl methacrylate; sulfur-containing methacrylates such as methylthiol, butylthiol, ethylsulfonylethyl, ethylsulfinylethyl, thiocyanatomethyl, 4-thiocyanatobutyl, methylsulfinylmethyl, 2-dodecylthioethyl methacrylate, or bis(methacryloyloxyethyl) sulfide; phosphorous-boron-silicone-containing methacrylates such as 2-(ethylenephosphito)propyl, dimethylphosphinomethyl, dimethylphosphonoethyl, diethylphosphatoethyl, 2-(dimethylphosphato)propyl, 2-(dibutylphosphono)ethyl methacrylate, diethyl methacryloylphosphonate, dipropyl methacryloyl phosphate, diethyl methacryloyl phosphite, 2-methacryloyloxyethyl diethyl phosphite, 2,3-butylene methacryloyl-oxyethyl borate, or methyidiethoxymethacryloyloxyethoxysilane. Examples of methacrylic amides and nitriles are N-methylmethacrylamide, N-isopropylmethacrylamide, N-phenylmethacrylamide, N-(2-hydoxyethyl)methacrylamide, 1-methacryloylamido-2-methyl-2-propanol, 4-methacryloylamido-4-methyl-2-pentanol, N-(methoxymethyl)methacrylamide, N-(dimethylaminoethyl)methacrylamide, N-(3-dimethylaminopropyl)methacrylamide, N-acetylmethacrylamide, N-methacryloylmaleamic acid, methacryloylamidoacetonitrile, N-(2-cyanoethyl) methacrylamide,1-methacryloylurea, N-phenyl-N-phenylethylmethacrylamide, N-(3-dibutylaminopropyl)methacrylamide, N,N-diethylmethacrylamide, N-(2-cyanoethyl)-N-methylmethacrylamide, N,N-bis(2-diethylaminoethyl)methacrylamide, N-methyl-N-phenylmethacrylamide, N,N′-methylenebismethacrylamide, N,N′-ethylenebismethacrylamide, or N-(diethylphosphono)methacrylamide. Optional monomer examples include acrolein, acrylic anhydride, acrylonitrile, acryloyl chloride, methacrolein, methacrylonitrile, methacrylic anhydride, methacrylic acetic anhydride, methacryloyl chloride, methacryloyl bromide, itaconic acid, butadiene, vinyl chloride, vinylidene chloride, or vinyl acetate.
Examples of acrylics include, but are not limited to, PARALOID™ AT-410 (73 percent in methyl amyl ketone, Tg=30° C., OH equivalent weight=880, acid number=25, Mw=9,000), AT-400 (75 percent in methyl amyl ketone, Tg=15° C., OH equivalent weight=650, acid number=25, Mw=15,000), AT-746 (50 percent in xylene, Tg=83° C., OH equivalent weight =1,700, acid number=15, Mw=45,000), and AT-63 (75 percent in methyl amyl ketone, Tg=25° C., OH equivalent weight=1,300, acid number=30), all available from Rohm and Haas, Philadelphia, Pa. Examples of styrene acrylics include, but are not limited to, JONCRYL™ 500 (80 percent in methyl amyl ketone, Tg=−5° C., OH equivalent weight=400), 550 (62.5 percent in PM-acetate/toluene=65/35, OH equivalent weight=600), 551 (60 percent in xylene, OH equivalent weight=600), 580 (Tg=50° C., OH equivalent weight=350, acid number=10, Mw=15,000), 942 (73.5 percent in n-butyl acetate, OH equivalent weight=400), and 945 (78 percent in n-butyl acetate, OH equivalent weight=310), all available from Johnson Polymer, Sturtevant, Wis.
The phenolic resins selected are, for example, comprised of condensation products of an aldehyde with a phenol source in the presence of an acidic or basic catalyst. The phenol source may be, for example, phenol, alkyl-substituted phenols such as cresols and xylenols, halogen-substituted phenols such as chlorophenol, polyhydric phenols such as resorcinol or pyrocatechol, polycyclic phenols such as naphthol and bisphenol A, aryl-substituted phenols, cyclo-alkyl-substituted phenols, aryloxy-substituted phenols, and combinations thereof. The phenol source may be phenol, 2,6-xylenol, o-cresol, p-cresol, 3,5-xylenol, 3,4-xylenol, 2,3,4-trimethyl phenol, 3-ethyl phenol, 3,5-diethyl phenol, p-butyl phenol, 3,5-dibutyl phenol, p-amyl phenol, p-cyclohexyl phenol, p-octyl phenol, 3,5-dicyclohexyl phenol, p-phenyl phenol, p-crotyl phenol, 3,5-dimethoxy phenol, 3,4,5-trimethoxy phenol, p-ethoxy phenol, p-butoxy phenol, 3-methyl-4-methoxy phenol, p-phenoxy phenol, multiple ring phenols, such as bisphenol A, and mixtures thereof. The aldehyde may be, for example, formaldehyde, paraformaldehyde, acetaldehyde, butyraldehyde, paraldehyde, glyoxal, furfuraldehyde, propinonaldehyde, benzaldehyde, and mixtures thereof.
Also, phenolic resins that may be selected are, for example, dicyclopentadiene type phenolic resins, phenol novolak resins, cresol novolak resins, phenol aralkyl resins, and combinations thereof; formaldehyde polymers with phenol, rtert-butylphenol, and cresol, such as VARCUM™ 29159 and 29101 (OxyChem Company) and DURITE™ 97 (Borden Chemical), formaldehyde polymers with ammonia, cresol, and phenol, such as VARCUM™ 29112 (OxyChem Company), formaldehyde polymers with 4,4′-(1-methylethylidene)bisphenol such as VARCUM™ 29108 and 29116 (OxyChem Company), or formaldehyde polymers with cresol and phenol such as VARCUM™ 29457 (OxyChem Company), DURITE™ SD-423A, SD-422A (Borden Chemical), or formaldehyde polymers with phenol and p-tert-butylphenol such as DURITE™ ESD 556C (Border Chemical). The phenolic resins can be used as purchased, or they can be modified to enhance certain properties thereof. For example, the phenolic resins can be modified with suitable plasticizers, including, but not limited to, polyvinyl butyral, polyvinyl formal, alkyds, epoxy resins, phenoxy resins (bisphenol A, epichlorohydrin polymer) polyamides, oils, and the like.
In embodiments, aminoplast resin refers, for example, to a type of amino resin generated from a nitrogen-containing substance and formaldehyde wherein the nitrogen-containing substance includes melamine, urea, benzoguanamine, and/or glycoluril. Melamine resins include amino resins generated from melamine and formaldehyde. Melamine resins are known under various trademarks, including but not limited to CYMEL™, BEETLE™, DYNOMIN™, BECKAMINE™, UFR™, BAKELITE™, ISOMIN™, MELAICAR™, MELBRITE™, MELMEX™, MELOPAS™, RESART™, and ULTRAPAS™. Urea resins can be considered as being prepared from urea and formaldehyde. Urea resins include, but are not limited to, CYMEL™, BEETLE™, UFRM, DYNOMIN™, BECKAMINE™, and AMIREME™; benzoguanamine resins include amino resins generated from benzoguanamine and formaldehyde, including, but not limited to, CYMEL™, BEETLE™, and UFORMITE™. Glycoluril resins can be considered amino resins generated from glycoluril and formaldehyde including, but not limited to, CYMEL™, and POWDERLINK™. The aminoplast resins can be highly alkylated or partially alkylated.
Melamine resin examples include those of the following formula/structure
wherein R1, R2, R3, R4, R5 and R6 each independently represents a hydrogen atom or a suitable substituent like a suitable hydrocarbon such as an alkyl chain with, for example, from 1 to about 8 carbon atoms, or from 1 to about 4 carbon atoms. In embodiments, the melamine resin is water-soluble, dispersible or nondispersible. Melamine resin examples include highly alkylated/alkoxylated, partially alkylated/alkoxylated, or mixed alkylated/alkoxylated, and more specifically, the melamine resin can be methylated, n-butylated or isobutylated. Examples of the melamine resin include highly methylated melamine resins such as CYMEL™ 350, 9370; methylated high imino melamine resins (partially methylolated and highly alkylated) such as CYMEL™ 323, 327; partially methylated melamine resins (highly methylolated and partially methylated) such as CYMEL™ 373, 370; high solids mixed ether melamine resins such as CYMEL™ 1130, 324; n-butylated melamine resins such as CYMEL™ 1151, 615; and n-butylated high imino melamine resins such as CYMEL™ 1158; iso-butylated melamine resins such as CYMEL™ 255-10, and a methylated melamine resin, about 78 to about 82 weight percent in isobutanol with a viscosity at 23° C. of about 2,500 to about 7,500, and available as CYMEL™ 323. CYMEL™ melamine resins are commercially available from CYTEC Corporation.
A number of specific examples of the melamine resin are methylated formaldehyde-melamine resin, methoxymethylated melamine resin, ethoxymethylated melamine resin, propoxymethylated melamine resin, butoxymethylated melamine resin, hexamethylol melamine resin, alkoxyalkylated melamine resins such as methoxymethylated melamine resin, ethoxymethylated melamine resin, propoxymethylated melamine resin, butoxymethylated melamine resin, and mixtures thereof.
Examples of a urea resin selected are, for example, of the formula
Benzoguanamine resins selected can be represented by the following formula/structure
wherein R1, R2, R3, and R4 each independently represents a hydrogen atom and/or a suitable hydrocarbon like alkyl with, for example, 1 to about 8 carbon atoms, or with 1 to about 4 carbon atoms.
A number of examples of the benzoguanamine resins are water soluble, dispersible or nondispersible. Thus, the benzoguanamine resin can be highly alkylated/alkoxylated, partially alkylated/alkoxylated, or mixed alkylated/alkoxylated, and more specifically, the benzoguanamine resin can be methylated, n-butylated or isobutylated. Examples of the benzoguanamine resin include CYMEL™ 659, 5010, and 5011. CYMEL™ benzoguanamine resins are commercially available from CYTEC Corporation.
In embodiments, the glycoluril resin selected is of the formula
wherein R1, R2, R3, and R4 each independently represents a hydrogen atom and/or a suitable hydrocarbon like alkyl with, for example, 1 to about 8 carbon atoms, or with 1 to about 4 carbon atoms. More specifically, examples of the glycoluril resin include water soluble, dispersible or nondispersible resins. The glycoluril resin can be highly alkylated/alkoxylated, partially alkylated/alkoxylated, or mixed alkylated/alkoxylated, and more specifically, the glycoluril resin can be methylated, n-butylated or isobutylated. Specific examples of the glycoluril resin include CYMEL™ 1170, and 1171. CYMEL™ glycoluril resins are commercially available from CYTEC Corporation.
In embodiments, the ratio of the co-resin of the polyol resin to the aminoplast resin can be from about 1/99 to about 99/1. In various embodiments, the ratio of the polyol resin to the aminoplast resin in the co-resin can be from about 20/80 to about 80/20, and from about 30/70 to about 70/30.
The metal oxide may be selected from, for example, ZnO, SnO2, TiO2, Al2O3, SiO2, ZrO2, In2O3, MoO3, and a complex oxide thereof. In various embodiments, the metal oxide has a powder volume resistivity varying from about 104 to about 1010 Ωcm at an about 100 kilograms/cm2 loading pressure, about 50 percent humidity, and at room temperature such as for example, from about 23 to about 27° C. In various embodiments, the metal oxide is TiO2. The metal oxide like TiO2 can be either surface treated or untreated. Surface treatments include, but are not limited to aluminum laurate, alumina, zirconia, silica, silane, methicone, dimethicone, sodium metaphosphate, and the like, and mixtures thereof. Examples of TiO2 include STR-60N™ (no surface treatment and powder volume resistivity of approximately 9×105 Ωcm) (available from Sakai Chemical Industry Company, Ltd.), FTL-100™ (no surface treatment and powder volume resistivity of approximately 3×105 Ωcm) (available from Ishihara Sangyo Laisha, Ltd.), STR-60™ (Al2O3 coated and powder volume resistivity of approximately 4×106 Ωcm) (available from Sakai Chemical Industry Co., Ltd.), TTO-55N™ (no surface treatment and powder volume resistivity of approximately 5×105 Ωcm) (available from Ishihara Sangyo Laisha, Ltd.), TTO-55A™ (Al2O3 coated and powder volume resistivity of approximately 4×107 Ωcm) (available from Ishihara Sangyo Laisha, Ltd.), MT-150W™ (sodium metaphosphated coated and powder volume resistivity of approximately 4×14 Ωcm) (available from Tayca), and MT-150AW™ (no surface treatment and powder volume resistivity of approximately 1×105 Ωcm) (available from Tayca). In various embodiments, a weight ratio of the metal oxide to the co-resin can be from about 20/80 to about 80/20, or from about 40/60 to about 65/35.
Further, the undercoat layer may optionally contain an acid catalyst primarily to enable rapid curing, such as the rapid curing of the polyol/aminoplast co-resin, and where curing can be at temperatures of from about 120° C. to about 195° C., or from about 145° C. to about 160° C. for a suitable period of, for example, from about 10 minutes to about 60 minutes, or from about 20 minutes to about 45 minutes. The acid catalyst can be a paratoluene sulfonic acid. In various embodiments, the acid catalyst is CYCAT™ 4040, commercially available from CYTEC Corporation. In various embodiments, the acid catalyst is an amine neutralized paratoluene sulfonic acid; NACURE™ 2107, commercially available from King Industries; an amine neutralized phenyl acid phosphate, NACURE™ 4575, commercially available from King Industries; an amine neutralized dinonylnaphthalenedisulfonic acid; NACURE™ 3525, commercially available from King Industries. The acid catalyst can be present in various suitable amounts, such as from about 0 percent to about 1 percent, or from about 0.1 percent to about 0.4 percent by weight of the total weight of the undercoat layer components.
The undercoat layer may optionally contain light scattering particles. In various embodiments, the light scattering particle has a refractive index different from the binder, and has a number average particle size greater than about 0.8 μm. Examples of the light scattering particles include, but are not limited to, inorganic materials such as amorphous silica, silicone ball and minerals. Typical minerals include, for example, metal oxides, silicates, carbonates, sulfates, iodites, hydroxides, chlorides, fluorides, phosphates, chromates, clay, sulfur and the like. In various embodiments, the light scattering particle is amorphous silica P-100, commercially available from Espirit Chemical Co. The light scattering particles can be present in an amount of, for example, from about 0 percent to about 10 percent, or from about 2 percent to about 5 percent by weight of a total weight of the undercoat layer components.
The undercoat layer may also contain one or more conventional binders. Examples of conventional binders include, but are not limited to, polyamides, vinyl chlorides, vinyl acetates, phenols, polyurethanes, melamines, benzoguanamines, polyimides, polyethylenes, polypropylenes, polycarbonates, polystyrenes, acrylics, methacrylics, vinylidene chlorides, polyvinyl acetals, epoxys, silicones, vinyl chloride-vinyl acetate copolymers, polyvinyl alcohols, polyesters, polyvinyl butyrals, nitrocelluloses, ethyl celluloses, caseins, gelatins, polyglutamic acids, starches, starch acetates, amino starches, polyacrylic acids, polyacrylamides, zirconium chelate compounds, titanyl chelate compounds, titanyl alkoxide compounds, organic titanyl compounds, silane coupling agents, and mixtures thereof. The conventional binders can be present in an amount of, for example, from about 1 to about 60 weight percent, or from about 10 to about 30 weight percent of the undercoat layer.
Further, the undercoat layer may additionally contain various colorants, examples of which are organic pigments and organic dyes, including, but not limited to, azo pigments, quinoline pigments, perylene pigments, indigo pigments, thioindigo pigments, bisbenzimidazole pigments, phthalocyanine pigments, quinacridone pigments, quinoline pigments, lake pigments, azo lake pigments, anthraquinone pigments, oxazine pigments, dioxazine pigments, triphenylmethane pigments, azulenium dyes, squalium dyes, pyrylium dyes, triallylmethane dyes, xanthene dyes, thiazine dyes, and cyanine dyes. The colorants can be present in an amount of, for example, from about 0.1 to about 30 weight percent, or from about 1 to about 10 weight percent of the undercoat layer. The undercoat layer may include inorganic materials, such as amorphous silicone, amorphous selenium, tellurium, a selenium-tellurium alloy, cadmium sulfide, antimony sulfide, titanium oxide, tin oxide, zinc oxide, zinc sulfide, and mixtures thereof. The inorganic materials can be present in an amount of, for example, from about 1 to about 60 weight percent, or from about 10 to about 30 weight percent of the undercoat layer.
The undercoat layer may, for example, be situated between an electroconductive support/substrate and the photogenerating layer. The undercoat or hole blocking layer is primarily effective for blocking leakage of charge from the electroconductive support/substrate to the photogenerating layer and/or for improving the adhesion between the electroconductive support/substrate and the photogenerating layer. The undercoat layer may be applied or coated onto a substrate by any suitable known technique, such as spraying, dip coating, draw bar coating, gravure coating, silk screening, air knife coating, reverse roll coating, vacuum deposition, chemical treatment, and the like. Additional vacuuming, heating, drying, and the like may be used to remove any solvent remaining after the application or coating to form the undercoat layer. Thus, the undercoat layer can be coated onto the conductive support/substrate from a suitable solvent. Suitable solvents include, but are not limited to, xylene/1-butanol/MEK, N,N-dimethyl formamide, N,N-dimethyl acetamide, dimethyl sulfoxide, tetrahydrofuran, dichloromethane, xylene, toluene, methanol, ethanol, 1-butanol, isobutanol, methyl ethyl ketone, methyl isobutyl ketone, and mixtures thereof. The thickness of the undercoat layer is, for example, from about 0.1 μm to 30 μm, from about 2 μm to 20 μm, or from about 4 μm to 15 μm. Also, in embodiments, electrophotographic imaging members can include undercoat layers having a thickness of from about 0.1 μm to 30 μm, from about 2 μm to 20 μm, or from about 4 μm to 15 μm.
Moreover, the hole blocking or undercoat layer can contain a number of components in addition to the adhesion promoter component including, for example, known hole blocking components, such as amino silanes, doped metal oxides; 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), and Z (4,4′-cyclohexylidenebisphenol); hexafluorobisphenol A (4,4′-(hexafluoro isopropylidene) diphenol), resorcinol, hydroxyquinone, catechin, and the like. The known hole blocking components can be present in an amount from about 1 to about 40 weight percent, or from about 10 to about 20 weight percent of the undercoat layer.
The thickness of the photoconductive 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 to about 150 microns.
The substrate may be opaque or substantially transparent and may comprise any suitable material, including known materials. Accordingly, the substrate may comprise a layer of an electrically nonconductive or conductive material such as an inorganic or an organic composition. As electrically nonconducting materials, there may be employed various resins known for this purpose including polyesters, polycarbonates, polyamides, polyurethanes, and the like, which are flexible as thin webs. An electrically conducting substrate may be any suitable metal of, for example, aluminum, nickel, steel, copper, and the like, or a polymeric material, as described above, filled with an electrically conducting substance, such as carbon, metallic powder, and the like, or an organic electrically conducting material. The electrically insulating or conductive substrate may be in the form of an endless flexible belt, a web, a rigid cylinder, a sheet, and the like. The thickness of the substrate layer depends on numerous factors, including strength desired and economical considerations. For a drum, as disclosed in a copending application referenced herein, this layer may be of substantial thickness of, for example, up to many centimeters or of a minimum thickness of less than a millimeter. Similarly, a flexible belt may be of substantial thickness of, for example, about 250 micrometers, or of minimum thickness of less than about 50 micrometers, provided there are no adverse effects on the final electrophotographic device.
In embodiments where the substrate layer is not conductive, the surface thereof may be rendered electrically conductive by an electrically conductive coating. The conductive coating may vary in thickness over substantially wide ranges depending upon the optical transparency, degree of flexibility desired, and economic factors.
Illustrative examples of substrates are as illustrated herein, and more specifically, substrates selected for the imaging members of the present disclosure, and which substrates can be opaque or substantially transparent comprise a layer of insulating material including inorganic or organic polymeric materials, such as MYLAR® a commercially available polymer, MYLAR® containing titanium, a layer of an organic or inorganic material having a semiconductive surface layer, such as indium tin oxide, or aluminum arranged thereon, or a conductive material inclusive of aluminum, chromium, nickel, brass, or the like. The substrate may be flexible, seamless, or rigid, and may have a number of many different configurations, such as for example, a plate, a cylindrical drum, a scroll, an endless flexible belt, and the like. In embodiments, the substrate is in the form of a seamless flexible belt. In some situations, it may be desirable to coat on the back of the substrate, particularly when the substrate is a flexible organic polymeric material, an anticurl layer, such as for example polycarbonate materials commercially available as MAKROLON®.
The photogenerating layer in embodiments is comprised of, for example, Type V hydroxygallium phthalocyanine or chlorogallium phthalocyanine, and a resin binder like poly(vinyl chloride-co-vinyl acetate)copolymer, such as VMCH™ available from Dow Chemical. Generally, the photogenerating layer can contain known photogenerating pigments, such as metal phthalocyanines, metal free phthalocyanines, alkylhydroxyl gallium phthalocyanines, hydroxygallium phthalocyanines, chlorogallium phthalocyanines, perylenes, especially bis(benzimidazo)perylene, titanyl phthalocyanines, and the like, and more specifically, vanadyl phthalocyanines, Type V hydroxygallium phthalocyanines, and inorganic components such as selenium, selenium alloys, and trigonal selenium. The photogenerating pigment can be dispersed in a resin binder similar to the resin binders selected for the charge transport layer, or alternatively no resin binder need be present. Generally, the thickness of the photogenerating layer depends on a number of factors, including the thicknesses of the other layers and the amount of photogenerating material contained in the photogenerating layer. Accordingly, this layer can be of a thickness of, for example, from about 0.05 micron to about 10 microns, and more specifically, from about 0.25 micron to about 2 microns when, for example, the photogenerating compositions are present in an amount of from about 30 to about 75 percent by volume. The maximum thickness of this layer in embodiments is dependent primarily upon factors, such as photosensitivity, electrical properties and mechanical considerations. The photogenerating layer binder resin is present in various suitable amounts, for example from about 1 to about 50, 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 solvent examples are cyclohexanone, acetone, methyl ethyl ketone, methanol, ethanol, butanol, amyl alcohol, toluene, xylene, chlorobenzene, carbon tetrachloride, chloroform, methylene chloride, trichloroethylene, tetrahydrofuran, dioxane, diethyl ether, dimethyl formamide, dimethyl acetamide, butyl acetate, ethyl acetate, methoxyethyl acetate, and the like.
The photogenerating layer may be comprised of amorphous films of selenium and alloys of selenium and arsenic, tellurium, germanium and the like, hydrogenated amorphous silicone and compounds of silicone and germanium, carbon, oxygen, nitrogen, and the like fabricated by vacuum evaporation or deposition. The photogenerating layers may also comprise inorganic pigments of crystalline selenium and its alloys; Group II to VI compounds; and organic pigments such as quinacridones; polycyclic pigments such as dibromo anthanthrone pigments, perylene and perinone diamines, polynuclear aromatic quinones, azo pigments including bis-, tris- and tetrakis-azos; hydroxygallium phthalocyanines, metal free phthalocyanines, metal phthalocyanines, hydroxy halophthalocyanines, titanyl phthalocyanines, and the like dispersed in a film forming polymeric binder and fabricated by solvent coating techniques.
Phthalocyanines have been selected as photogenerating materials in laser printers using infrared exposure systems usually desired for photoreceptors exposed to low-cost semiconductor laser diode light exposure devices. The absorption spectrum and photosensitivity of the phthalocyanines depend on the central metal atom of the compound. Many metal phthalocyanines, which can be selected for the photogenerating layer, have been reported and include oxyvanadium phthalocyanine, chloroaluminum phthalocyanine, copper phthalocyanine, oxytitanium phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine magnesium phthalocyanine and metal free phthalocyanine. The phthalocyanines exist in many crystal forms, and have a strong influence on photogeneration.
Examples of polymeric binder materials that can be selected as the matrix for the photogenerating layer are illustrated in U.S. Pat. No. 3,121,006, the disclosure of which is totally incorporated herein by reference. Examples of binders are thermoplastic and thermosetting resins, such as polycarbonates, polyesters, polyamides, polyurethanes, polystyrenes, polyarylethers, polyarylsulfones, polybutadienes, polysulfones, polyethersulfones, polyethylenes, polypropylenes, polyimides, polymethylpentenes, poly(phenylene sulfides), poly(vinyl acetate), polysiloxanes, polyacrylates, polyvinyl acetals, polyamides, polyimides, amino resins, phenylene oxide resins, terephthalic acid resins, phenoxy resins, epoxy resins, phenolic resins, polystyrene and acrylonitrile copolymers, poly(vinyl chloride), vinyl chloride and vinyl acetate copolymers, acrylate copolymers, alkyd resins, cellulosic film formers, poly(amideimide), styrenebutadiene copolymers, vinylidene chloride-vinyl chloride copolymers, vinyl acetate-vinylidene chloride copolymers, styrene-alkyd resins, poly(vinyl carbazole), and the like. These polymers may be block, random or alternating copolymers.
The photogenerating composition or pigment is present in the resinous binder composition in various amounts. Generally, however, from about 5 percent by volume to about 90 percent by volume of the photogenerating pigment is dispersed in about 10 percent by volume to about 95 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 8 percent by volume of the photogenerating pigment is dispersed in about 92 percent by volume of the resinous binder composition.
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 coating of the photogenerating layer on the UCL in embodiments of the present disclosure can be accomplished with spray, dip or wire-bar methods such that the final dry thickness of the photogenerating layer is as illustrated herein, and can be, for example, from about 0.01 to about 30 microns after being dried at, for example, about 40° C. to about 150° C. for about 1 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. The hole blocking layer or UCL may be applied to the electrically conductive surface prior to the application of a photogenerating layer.
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 optional adhesive layers usually in contact with or situated between the hole blocking layer and the photogenerating layer, there can be selected various known substances inclusive of copolyesters, polyamides, poly(vinyl butyral), poly(vinyl alcohol), polyurethane, and polyacrylonitrile. This layer is, for example, of a thickness of from about 0.001 micron to about 1 micron, or from about 0.1 to about 0.5 micron. Optionally, this layer may contain effective suitable amounts, for example from about 1 to about 10 weight percent, of conductive and nonconductive particles, such as zinc oxide, titanium dioxide, silicone nitride, carbon black, and the like, to provide, for example, in embodiments of the present disclosure, further desirable electrical and optical properties.
A number of charge transport materials, especially known hole transport molecules, may be selected for the charge transport layer, examples of which are aryl amines of the formula/structure, and which layer is generally 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
wherein X is a suitable hydrocarbon like alkyl, alkoxy, and aryl; a halogen, or mixtures thereof, and especially those substituents selected from the group consisting of Cl and CH3; and molecules of the following formula
wherein X and Y are a suitable substituent like a hydrocarbon, such as 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 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 layer or 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; and more specifically, polycarbonates such as poly(4,4′-isopropylidene-diphenylene)carbonate (also referred to as bisphenol-A-polycarbonate), poly(4,4′-cyclohexylidinediphenylene)carbonate (also referred to as bisphenol-Z-polycarbonate), poly(4,4′-isopropylidene-3,3′-dimethyl-diphenyl) carbonate (also referred to as bisphenol-C-polycarbonate), and the like. In embodiments, electrically inactive binders are comprised of polycarbonate resins with a molecular weight of from about 20,000 to about 100,000, or with a molecular weight Mw of from about 50,000 to about 100,000 preferred. Generally, the transport layer contains from about 10 to about 75 percent by weight of the charge transport material, and more specifically, from about 35 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 overcoating layer may comprise charge transporting small molecules dissolved or molecularly dispersed in a film forming electrically inert polymer such as a polycarbonate. In embodiments, “dissolved” refers, for example, to forming a solution in which the small molecule is dissolved in the polymer to form a homogeneous phase; and “molecularly dispersed in embodiments” refers, for example, to charge transporting molecules dispersed in the polymer, the small molecules being dispersed in the polymer on a molecular scale. Various charge transporting or electrically active small molecules may be selected for the charge transport layer or layers. In embodiments, charge transport refers, for example, to charge transporting molecules as a monomer that allows the free charge generated in the photogenerating layer to be transported across the transport layer.
Examples of hole transporting molecules 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.
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 layers is from about 0 to about 20, from about 1 to about 10, or from about 3 to about 8 weight percent.
A number of processes may be used to mix and thereafter apply the charge transport layer or layers coating mixture to the photogenerating layer. Typical application techniques include spraying, dip coating, roll coating, wire wound rod coating, and the like. Drying of the charge transport deposited coating may be effected by any suitable conventional technique such as oven drying, infrared radiation drying, air drying, and the like.
The thickness of each of the charge transport layers in embodiments is, for example, from about 10 to about 75, from about 15 to about 50 micrometers, but thicknesses outside these ranges may in embodiments also be selected. The charge transport layer should be an insulator to the extent that an electrostatic charge placed on the hole transport layer is not conducted in the absence of illumination at a rate sufficient to prevent formation and retention of an electrostatic latent image thereon. In general, the ratio of the thickness of the charge transport layer to the photogenerating layer can be from about 2:1 to about 200:1, and in some instances 400:1. The charge transport layer is substantially nonabsorbing to visible light or radiation in the region of intended use, but is electrically “active” in that it allows the injection of photogenerated holes from the photoconductive layer or photogenerating layer, and allows these holes to be transported 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 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 can be, for example, 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 photoconductor. 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 following Examples are provided. All proportions are by weight unless otherwise indicated.
Illustrative imaging members or photoconductors were fabricated as follows. Multilayered photoreceptors of the rigid drum design were fabricated by conventional coating technology with an aluminum drum of 34 millimeters in diameter as the substrate. The photoreceptors (Comparative Example 1, Examples I, II, III, IV and V) contained the same photogenerating layer and the same charge transport layer. The differences are that Comparative Example 1 contained an undercoat layer (UCL) comprising an acrylic polyol resin, a melamine resin, and titanium oxide; Example I contained the same layers as Comparative Example 1 except that a POSS silanol was incorporated into the UCL; Example II contains the same layers as Comparative Example 1 except that a non-POSS silanol is incorporated into the UCL; Example III contains an undercoat layer (UCL) comprising a phenolic resin, titanium oxide and a POSS silanol; Example IV contains an undercoat layer (UCL) comprising a melamine resin, a styrene acrylic copolymer, titanium oxide and a POSS silanol; Example V contains an undercoat layer (UCL) comprising a melamine resin, a phenolic resin, titanium oxide and a POSS silanol; Example VI is similar to Comparative Example 1 except with different CTL thickness; and Example VII is similar to Example 1 except with a different CTL thickness.
The undercoat layer was prepared as follows: a titanium oxide/acrylic polyol resin/melamine resin dispersion was prepared by ball milling 15 grams of titanium dioxide (MT-150W™, Tayca Company), 5 grams of the acrylic polyol resin (PARALOID™ AT-410, Rohm and Haas), and 5 grams of the melamine resin (CYMEL™ 323, CYTEC Corporation) in 15 grams of methyl ethyl ketone with 120 grams of 1 millimeter diameter sized ZrO2 beads for 1 day. The resulting titanium dioxide dispersion was filtered with a 20 micrometer pore size nylon cloth, and then the filtrate was measured with Horiba Capa 700 Particle Size Analyzer, and there was obtained a median TiO2 particle size of 50 nanometers in diameter and a TiO2 particle surface area of 25 m2/gram with reference to the above TiO2/PARALOID™/CYMEL™ dispersion. Then an aluminum drum, cleaned with detergent and rinsed with deionized water, was coated with the above generated coating dispersion, and subsequently, dried at 145° C. for 30 minutes, which resulted in an undercoat layer deposited on the aluminum and comprised of TiO2/PARALOID™/CYMEL™ with a weight ratio of about 60/20/20 and a thickness of 4 μm.
The photogenerating layer was prepared as follows: 2.7 grams of Type B chlorogallium phthalocyanine (ClGaPc) pigment was mixed with about 2.3 grams of polymeric binder VMCH (Dow Chemical), 30 grams of xylene and 15 grams of n-butyl acetate. 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 μm nylon cloth filter, and the solid content of the dispersion was diluted to about 5.8 weight percent with a mixture of xylene/n-butyl acetate=2/1 (weight/weight). The ClGaPc photogenerating layer dispersion was applied on top of the above undercoat layer. The thickness of the photogenerating layer was approximately 0.2 μm.
Subsequently, a 30 μm charge transport layer was coated on top of the photogenerating layer, which coating dispersion was prepared as follows: 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, were dissolved/dispersed in a solvent mixture of 20 grams of tetrahydrofuran (THF) and 6.7 grams of toluene via CAVIPRO™ 300 nanomizer (Five Star technology, Cleveland, Ohio). The charge transport layer was dried at about 120° C. for about 40 minutes.
The process of Comparative Example 1 was repeated except that to the above undercoat layer dispersion of Comparative Example 1 were added 0.45 grams of the silanol phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.). The dispersion was allowed to mix for at least 4 hours before coating it on the substrate.
The process of Comparative Example 1 was repeated except that to the above undercoat layer dispersion of Comparative Example 1 are added 0.15 grams of tris(4-(dimethylamino)phenyl)silanol. The dispersion is allowed to mix for at least 4 hours before coating it on the substrate.
A photoconductor is prepared by repeating the process of Comparative Example 1 except that the undercoat layer is prepared as follows: a silanol/titanium oxide/phenolic resin dispersion is prepared by ball milling 0.3 grams of the silanol phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.), 15 grams of titanium dioxide (MT-150W™, Tayca Company), and 10 grams of the phenolic resin (VARCUM™ 29159, OxyChem Company, Mw of about 3,600, viscosity of about 200 cps) in 7.5 grams of 1-butanol, and 7.5 grams of xylene with 120 grams of 1 millimeter diameter sized ZrO2 beads for 5 days. The resulting silanol/titanium dioxide/phenolic resin dispersion is filtered with a 20 micrometer pore size nylon cloth. Then, an aluminum drum, cleaned with detergent and rinsed with deionized water, is coated with the above generated coating dispersion, and subsequently, dried at 160° C. for 15 minutes, which results in an undercoat layer deposited on the aluminum and comprised of silanol/TiO2NARCUM™ with a weight ratio of about 1.2/60/40 and a thickness of 10 μm.
A photoconductor is prepared by repeating the process of Comparative Example 1 except that the undercoat layer is prepared as follows: in a 120 milliliter glass bottle, 1.5 grams of the silanol phenyl-POSS trisilanol (S01458™, available from Hybrid Plastics, Fountain Valley, Calif.), 15 grams of TiO2 (MT-150W™, available from Tayca Company), 5 grams of JONCRYL™580 (available from Johnson Polymers LLC), 5 grams of CYMEL™323 (80 weight percent in isopropanol, available from CYTEC Industries Inc.) and 30 grams of MEK were mixed with 150 grams of 2 millimeter ZrO2 beads. The ball milling is carried out for 30 hours under 200 rpm. The dispersion is filtered through a 20 μm nylon cloth filter. Then an aluminum drum, cleaned with detergent and rinsed with deionized water, is coated with the above generated coating dispersion, and subsequently dried at 160° C. for 40 minutes, which results in an undercoat layer deposited on the aluminum and comprised of silanol/TiO2/JONCRYL™/CYMEL™ with a weight ratio of about 6/60/20/20 and a thickness of 15 μm.
A photoconductor is prepared by repeating the process of Comparative Example 1 except that the undercoat layer is prepared as follows: in a 120 milliliter glass bottle, 3 grams of the silanol phenyl-POSS trisilanol (SO1458™, available from Hybrid Plastics, Fountain Valley, Calif.), 15 grams of TiO2 (MT-15OW™, available from Tayca Company), 5 grams of the phenolic resin (VARCUM™ 29159, OxyChem Company, Mw of about 3,600, viscosity of about 200 cps), 5 grams of CYMEL™ 323 (80 weight percent in isopropanol, available from CYTEC Industries Inc.) and 30 grams of MEK were mixed with 150 grams of 2 millimeter ZrO2 beads. The ball milling is carried out for 5 days under 200 rpm. The dispersion is filtered through a 20 μm nylon cloth filter. Then an aluminum drum, cleaned with detergent and rinsed with deionized water, is coated with the above generated coating dispersion, and subsequently, dried at 160° C. for 40 minutes, which results in an undercoat layer deposited on the aluminum and comprised of silanol/TiO2NARCUM™/CYMEL™ with a weight ratio of about 12/60/20/20 and a thickness of 15 μm.
A photoconductor is prepared by repeating the process of Comparative Example 1 except that the charge transport layer was coated to a thickness of 15 microns.
A photoconductor is prepared by repeating the process of Example I except that the charge transport layer was coated to a thickness of 15 microns.
The above prepared first two photoreceptor devices (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; the exposure light source was a 780 nanometer light emitting diode. The aluminum drum was rotated at a speed of 55 revolutions per minute to produce a surface speed of 277 millimeters per second or a cycle time of 1.09 seconds. The xerographic simulation was completed in an environmentally controlled light tight chamber at ambient conditions (40 percent relative humidity and 22° C.). Two photoinduced discharge characteristic (PIDC) curves were generated, which curves indicated that the incorporation of silanols into the undercoat layer had little or minimal adverse effects on PIDC.
The above prepared final two photoconductor devices (Example VI and Example VII) were acclimated for 24 hours before testing at 80° F. and 80 percent relative humidity for a background test. Print testing was accomplished in a Xerox Corporation Copeland Work Centre Pro 3545 using the K station at the process speed of 52 millimeters/second and 165 millimeters/second. Background levels were measured against Technology & Systems Integration delivery Unit (TSIDU) SIR scale (from Grade 1 to Grade 7). The smaller the background grade, the better the print quality. The background results are summarized in Table 1. Thus, incorporation of a hydrophobic silanol into the undercoat layer reduced background by almost 4 grades.
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.
U.S. Application No. (not yet assigned) (Attorney Docket No. 20060304-US-NP), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, on Polyester Containing Member, by Liang-Bih Lin et al. U.S. Application No. (not yet assigned) (Attorney Docket No. 20060305-US-NP), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, on Polyarylate Containing Member, by Liang-Bih Lin et al. U.S. Application No. (not yet assigned) (Attorney Docket No. 20060444-US-NP), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, on Phosphate Ester Containing Photoconductors, by Daniel V. Levy et al. U.S. Application No. (not yet assigned) (Attorney Docket No. 20060445-US-NP), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, on Silicone Free Polyester Containing Member, by Daniel V. Levy et al. U.S. Application No. (not yet assigned) (Attorney Docket No. 20060454-US-NP), filed concurrently herewith, the disclosure of which is totally incorporated herein by reference, on Phosphoric Acid Ester Containing Photoconductors, by Jin Wu et al. Disclosed in copending application U.S. application Ser. No. 10/942,277, U.S. Publication No. 20060057480, the disclosure of which is totally incorporated herein by reference, is a photoconductive member comprised of a supporting substrate, a hole blocking layer thereover, a photogenerating layer, and a charge transport layer, and wherein the hole blocking layer is comprised of a metallic component and a binder component, such as a phenolic resin. Disclosed in copending application U.S. application Ser. No.11/211,757, the disclosure of which is totally incorporated herein by reference, is an electrophotographic imaging member comprising a support layer, an undercoat layer of a binder of metal oxide nanoparticles, and a co-resin comprising a phenolic resin and an aminoplast resin; a charge generation layer, and a charge transport layer. Disclosed in copending application U.S. application Ser. No.11/403,981, the disclosure of which is totally incorporated herein by reference, is an electrophotographic imaging member, comprising a substrate, an undercoat layer disposed on the substrate, wherein the undercoat layer comprises a polyol resin, an aminoplast resin, and a metal oxide dispersed therein; and at least one imaging layer formed on the undercoat layer, and wherein the polyol resin is, for example, selected from the group consisting of acrylic polyols, polyglycols, polyglycerols, and mixtures thereof. The appropriate components and processes, thickness of each of the layers, component amounts in each of the layers, and number of layers, of the above copending applications, especially copending applications U.S. application Ser. No. 11/211,757; U.S. application Ser. No. 11/403,981; U.S. application Ser. No. (not yet assigned) (Attorney Docket No. 20060304-US-NP), U.S. application Ser. No. (not yet assigned) (Attorney Docket No. 20060305-US-NP), U.S. application Ser. No. (not yet assigned) (Attorney Docket No. 20060445-US-NP), (Attorney Docket No. 20060444-US-NP), and (Attorney Docket No. 20060454-US-NP), and also U.S. application Ser. No. 11/410,593, may be selected for the present disclosure in embodiments thereof.
