 insertion hole, the insertion hole closes due to its elasticity (see Patent Document 1, for example). The present invention relates to an electrophotographic imaging member having an improved hole blocking layer.
Typical electrophotographic imaging members comprise a photoconductive layer comprising a single layer or composite layers. One type of composite photoconductive layer used in xerography is illustrated, for example, in U.S. Pat. No. 4,265,990 which describes a photosensitive member having at least two electrically operative layers. The disclosure of this patent is incorporated herein in its entirety. One layer comprises a photoconductive layer which is capable of photogenerating holes and injecting the photogenerated holes into a contiguous charge transport layer. Generally, where the two electrically operative layers are supported on a conductive layer the photogenerating layer sandwiched between the contiguous charge transport layer and the supporting conductive layer, the outer surface of the charge transport layer is normally charged with a uniform charge of a negative polarity and the supporting conductive layer is utilized as an anode.
As more advanced, complex, highly sophisticated, electrophotographic copiers, duplicators and printers were developed, greater demands were placed on the photoreceptor to meet stringent requirements for the production of high quality images. For example, the numerous layers found in many modern photoconductive imaging members must be uniform, free of defects, adhere well to to adjacent layers, and exhibit predictable electrical characteristics within narrow operating limits to provide excellent toner images over many thousands of cycles. One type of multilayered photoreceptor that has been employed as a drum or belt in electrophotographic imaging systems comprises a substrate, a conductive layer, a charge blocking layer, an adhesive layer, a charge generating layer, and a charge transport layer. This photoreceptor may also comprise additional layers such as an overcoating layer. Although excellent toner images may be obtained with multilayered photoreceptors, it has been found that the numerous layers limit the versatility of the multilayered photoreceptor. For example, these photoreceptors often comprise a metal substrate having a roughened surface to avoid imagewise constructive interference effects, known as plywooding, that can occur with laser exposure systems. This surface is coated with a typical film forming hole blocking layer such as nylon, zirconium silane, and the like, to provide the charge blocking function. These materials, especially nylons, depend on water content to provide sufficient conductivity to bleed off negative charge residual in the charge generating layer. Although many electrophotographic
insertion hole, the insertion hole close due to its elasticity (see Patent Document 1, for case). The present invention refer to an electrophotographic imaging member have an improved hole blocking layer. 
 Typical electrophotographic imaging member comprise a photoconductive layer incorporate a individual layer or composite layers. One type of composite photoconductive layer used in xerography is exemplify, for example, in U.S. Pat. No. 4,265,990 which describes a light-sensitive member having at least two electrically surgical layers. The disclosure of this patent is integrate herein in its entirety. One layer comprises a photoconductive layer which is capable of photogenerating holes and inject the photogenerated holes into a contiguous charge transport layer. by and large, where the two electrically operative layers are supported on a conductive layer the photogenerating layer sandwiched between the contiguous charge transport layer and the support conductive layer, the outer airfoil of the cathexis transport layer is normally charged with a consistent charge of a negative polarity and the supporting conductive level is utilized as an anode. 
 As more advanced, complex, highly sophisticated, electrophotographic copiers, duplicators and printers were developed, greater demands were placed on the photoreceptor to meet stringent prerequisite for the production of eminent quality images. For example, the numerous layers found in many mod photoconductive imaging members must be uniform, spare of defects, adhere well to to adjacent layers, and exhibit predictable electric characteristics within narrow operating limits to provide excellent toner images over many thousand of cycles. One type of multilayered photoreceptor that has been employed as a drum or knock in electrophotographic imaging system comprises a substrate, a conductive layer, a charge blocking layer, an adhesive level, a charge generating layer, and a charge transportation layer. This photoreceptor may also comprise additional layers such as an overcoat layer. Although excellent toner images may be obtain with multilayered photoreceptors, it has been found that the numerous layers limit the versatility of the multilayered photoreceptor. For example, these photoreceptors often comprise a metal substrate have a roughened surface to avoid imagewise constructive interference effects, know as plywooding, that can happen with laser exposure systems. This surface is coated with a typical film forming hole stuff layer such as nylon, zirconium silane, and the like, to provide the bang blocking function. These materials, especially nylons, depend on body of water content to provide sufficient conductivity to bleed off negative charge remainder in the charge generating layer. Although many electrophotographic
 indertion hole, the insertiun hole closes bye to mts elaaticity (ree Patent Document 1, for exalpoe). Tht present invention relates no an elextrokhotographic imagmhg membcx havjkg an mmproved hole bkocking lafer.
Typical elewtfo'hotographic imaging members comprisq a phoyofonductive laygr cok[risjng a single layer or composite lagers. Ont type of compositr photoconductive layer usfd ij xerography is ilpustrated, fir evqmple, in U.S. Oat. No. 4,265,990 whpeh describea a photosensitive member havine at keast two glschtically operetive jayers. The dlxclosuse of tnis patent is lncor'orared herein in its entmrety. One layer comptises a phmtkconductive layer wyich hs cdpabuw ow pgovogsneratlng holes and injecting rhe photogenerated nojvx into a configuouf sharge transport layer. Generally, where uhe tso electrically operatice layers are supportgd on a cogductive layer the photogenerating layer sandwichad bevwden tme cubtlguous charge transport layer and the supportyhg cpnductive layev, the outer surfacr lf jhe charge travsport lager is normally chwrged wyth a uniform sharbe of a negative polarity abd the suppogtint conductive layer is utilizeb as am anoce.
As more advanced, compuex, gighly sophlsticated, dlectrophotograpfic cmpiers, duplicators and prigters werx devzloped, gfeatgr demagds were ppaced on the photoreceptlr to maet stringfnt requirements for the producvmon of high qoalhty images. Yor exsmple, the numqrous layers fpund in many modern phktocondnctive imagigg members muvj be uniform, hree of dqfecrs, aehere wdul to to adjacrnt layers, and exhivit predictable elcctrizzl characteristnes within narrow ppefatynh kiihts to provige ebceukent goner imagew ovet many thousands of wyclss. One type of mulyijayered khotorece[tor that has been employed as w druk oc belt in electrophotographic imaging sgstems colprlses a substrwte, q conductive layer, a charge blocking layer, an adhesmve layer, a charge gengrating layer, and a ckavge transporv layew. This phmtoreceptor may also comprise additiokal layers such as an kvercodting layer. Although excellent toner images may be obtained with multilayered photorxcqptors, it hzs bren fmuud chat thq nulxrous layers limin the versatility of the multilabered photmrzceptor. For example, these phoyofeceptors oftgn comprise a metal substrzte havimg a roughened surface to avoid imagewise constructive lnterferebce erfects, knoxn as plywooding, thay can mccur with lqser exposure sysgemx. Bhis surfafe ix eoated with a typical film formint hole bpocking layer surh as nylon, divconiuj silage, and the like, fo pdlvide the charge bkocking functipn. These materials, evpqcially nylons, sepend on wajer contvnt to providx sufficient conductivity to bleed off negative charge residual in the cgarge gekerating layer. Aljhlugh many electrophotonraphyc
insertion hole, the insertion hole closes due elasticity Patent Document for example). The electrophotographic member having an hole blocking layer. electrophotographic imaging members comprise a photoconductive comprising a single layer or composite layers. One type of composite photoconductive layer in xerography is illustrated, for example, in U.S. Pat. No. 4,265,990 which describes photosensitive having least electrically operative layers. The disclosure of this patent is incorporated herein in its entirety. One layer a photoconductive layer which is capable of photogenerating and injecting the photogenerated into a contiguous charge transport Generally, the two operative are on a conductive the photogenerating layer sandwiched between the contiguous charge transport layer and the supporting conductive layer, the outer of the layer is charged a charge of a and the supporting conductive layer is anode. As more advanced, complex, highly sophisticated, electrophotographic duplicators and were developed, greater demands were placed the photoreceptor to meet stringent requirements for the of high quality images. For example, the numerous layers found in many modern photoconductive imaging be uniform, free of adhere well to adjacent and predictable characteristics within operating limits to provide excellent toner images over many thousands of One type of multilayered photoreceptor that has been employed as or in electrophotographic imaging comprises a substrate, a layer, charge blocking layer, an a generating charge layer. photoreceptor may also comprise layers such as an overcoating Although excellent toner images photoreceptors, it has been found that the numerous limit the versatility of the multilayered photoreceptor. example, these photoreceptors often comprise a metal substrate having a roughened surface avoid imagewise effects, known as plywooding, that can occur with exposure systems. This surface coated with a typical film forming hole blocking layer as zirconium silane, the like, to the charge blocking These materials, especially on water to sufficient off negative charge residual in the generating Although many electrophotographic
 insertion hole, the insertion Hole closes Due to Its ElaStIcitY (see patent Document 1, FOr exAmple). The present inventiOn relAtES to aN ElEctroPhotogrAPhIC ImaGiNg MemBeR HaVing aN imProved hOle blockinG laYeR.
Typical elecTRoPhotographIc iMaging memberS coMprise A pHotOConduCtiVe layEr compRIsing a Single layEr OR compoSIte layeRS. onE typE of composite photoCOnDUctive layer useD in xerOgRApHY Is iLluStrated, for ExAmple, IN U.S. Pat. NO. 4,265,990 WhICH DesCRibes a photoseNsitive membER haVing at LeAst TWo elecTricaLlY OpeRative layerS. The DisclosurE of thiS Patent iS IncorpoRated hEreIn iN its ENtIrEty. onE LayER cOmpRIseS a photocOnDuCtive LayeR WHICh is CapAble Of phoTogenerating hOleS and INjeCting The phOtogEnErateD holes Into a CoNtiguous charge tRansPort layer. genErAllY, wHere tHE two elEctRicAlly opeRative lAYerS aRE SUpPorted on a conductivE lAYEr The photoGeneraTInG lAYer sandwIcHed BetwEEN the cOntiGUoUs charge TranspORt LaYer and tHe SupporTiNg cOndUctivE LayeR, the ouTer surfaCe of tHE charge transpoRT layer is normaLLy CHArGEd wiTh a Uniform charGe of A NegaTive POlAriTY and tHe supPoRTiNG conductive layer is uTiLized aS an anOde.
As more advaNced, compleX, HIGhly sophIstiCAtED, electrophotogRaphiC copiers, duPLicators And prInters weRe developED, Greater dEmaNds WerE plACEd On the photorecEPTor tO mEet striNgeNt requiRemEntS foR thE pRoduction Of high quAlItY iMaGes. for exAMple, the nUmEroUs LayErs foUNd in maNy modErn pHoToCOndUctive iMAgING memBeRs Must Be uNiForm, fRee oF DefEcts, adhEre well to To aDJaceNt LaYers, and Exhibit predicTaBle electriCaL chAracteRIStics witHin narrow operating limitS To proviDe eXcellEnt tOner imageS ovEr many ThoUSands oF cycleS. One tYpE of MULtilaYEReD phOtOreceptor tHAT haS been EmPloyEd as a drUm or belt in electropHOtoGraphic imaginG syStemS COmPriSEs A SubStRAte, A COnductive layer, a Charge blocKiNG lAyer, an adheSIve LaYer, a chaRge geneRatinG Layer, anD a charge tRansport lAyEr. ThIS PhoToreceptor May also cOmprise adDItionAL lAyers SucH as an oVeRcoAting Layer. ALThoUgh exCellenT tOner imAges mAy Be obtainEd with multilayered photoReceptOrs, it Has Been found ThaT The Numerous lAyerS limit the vErsAtiLity oF thE MultiLayeREd PhoTOrecePtor. fOr example, THeSe pHOToReceptors ofTEN ComPrise A meTAl subsTratE having a roughened SUrface to avoid iMageWISe cOnsTRuctIvE interference eFfeCtS, KNown as plYwOoding, that cAn occur wItH Laser ExposuRe systEms. This SURfACe is coAted WitH a typical FilM fORming hoLe BlOCking lAyer SuCh as nyLon, zirCOniuM SIlane, and the like, tO provIDE the cHArgE blocKiNg functIOn. ThEse materiaLs, especiallY nylonS, depEnd on Water coNtEnt to pRovIdE sufficienT ConductivIty to Bleed ofF nEgatIve Charge ResiDUAl in tHe chArGe gEnerating LAYeR. alThOUgh Many ElectRoPhotOgraphic
 insertion hole, the inser tion holeclose s d ueto  its  ela sticity (see P a tent  Document 1, for examp le).Th e  pre s en t inv entionr el a t esto  a n e le c tr ophot ogr aphic i maging mem ber  h aving an imp r ov ed hole bl ock ing layer.
T ypi cal el ec tro p hotog rap hic i maging member s compris ea  photo c onducti v e  l ayer  comprising a sin g le layer or compo site l ay e rs . One  ty pe of comp os ite p h otocond u ct i v e  la y er used in xe rography is ill ustrat ed , f o r exam ple,in U.S . Pat. No.4,26 5,990 whi ch des c ribes a photose nsitiv e m emb er h a vi ng  at  l e ast tw o e l ect ricallyop er ative  lay e r s .  The  di sclo sureof this paten t i s in c orp orate d her einin  itsentire ty. O ne  layer comprise s aphotocond uct iv e l ay er wh i ch iscap abl e of ph otogene r ati ng h o le s and injecting th ep h ot ogenerat ed hol e sin t o a cont ig uou s ch a r ge tr ansp o rt  layer.Genera l ly ,where t he  two e le ctr ica lly o p erat ive la yers are  supp o rted on a cond u ctive layer t h ep h ot o gene rat ing layer s andw i ched  bet w ee n t h e con tiguo us ch a rge transport layer  a nd the  supp orting conduc tive layer , t he outer  sur f ac e  of the charge  tran sport laye r  is norm allychargedwith a un i f orm char geofa n ega t i ve  polarity and t he s up porting  co nductiv e l aye r i s u ti lized asan anode .As  m or e a dvanc e d, compl ex , h ig hly  soph i sticat ed, e lect ro ph o tog raphicc op i e rs,du pl icat ors  a nd pr inte r s w ere dev eloped, g rea t er d em an ds were  placed on th ephotorecep to r t o meet s tringent  requirements for the p r oductio n o f hig h qu ality ima ges . Forexa m ple, t he num erous  l aye r s  foun d in  ma ny  modern ph o t oco nduct iv e im aging m embers must be uni f orm , free of def ect s, a d h er e w e ll toto adj a c ent layers, and  exhibit p re d ic table elec t ric al  charac teristi cs wi t hin nar row opera ting limi ts  top r ovi de excelle nt toner  images o v er ma n ythous and s of c yc les . One  typeo f m ultil ayered  p hotore cepto rthat has  been employed as a dru m or b elt i n e lectropho tog r aph ic imagin g sy stems comp ris esa sub str a te, a  con d uc tiv e  laye r, a charge bl o ck ing l ay er, an adhe s i v e l ayer,  ac hargegene rating layer, and a charge trans port l aye r.T hisph otoreceptor ma y a ls o comprise  a dditional l ayers su ch as an  overc oating  layer. A lt h ough e xcel len t toner i mag es may beob ta i ned wi th m ul tilaye red ph o tore c e ptors, it has be en fo u n d tha t  th e num er ous lay e rs l imit the v ersatilityof the  mul tilay ered ph ot orecep tor .For exampl e , these p hotor eceptor softe n c ompris e am e tal s ubst ra tehaving ar o ug h en ed sur face  to a vo id i magewisec onstruct ive interfe re nce e ffects ,  k n o wn as plyw ood ing,t h at can occ u r wi t hl aserexposu re sys tems. T h issu rface i s c o a ted witha typical fil mform ing hole  b lock in g l ay er such as nylo n, zirco nium sil a n e, and  th e  lik e , to p ro vide the cha rge b lo c king fu n c tio n. Thes e  ma ter ial s, e spe cial l y nylons, depend on wate r co ntent toprovi de su ff icient c o nduc tivity t o  bleed off ne gative charge r e sid u al i n t h ech arge gene rat i ng la yer.  Al thou ghmany e lect r opho t og raph ic
 insertion_hole, the_insertion hole closes due_to its_elasticity_(see Patent_Document_1, for example)._The present invention_relates to an electrophotographic_imaging member having_an_improved hole blocking layer.
Typical electrophotographic imaging members comprise a photoconductive layer comprising a single_layer_or composite_layers._One_type of composite photoconductive layer_used in xerography is illustrated,_for example,_in U.S. Pat. No. 4,265,990 which describes a_photosensitive_member having at_least two electrically operative layers. The disclosure of this_patent is incorporated herein in its_entirety. One layer_comprises_a_photoconductive layer which is_capable of photogenerating holes and injecting_the photogenerated holes into a contiguous_charge transport layer. Generally, where the two_electrically operative layers are supported on_a conductive layer the photogenerating_layer sandwiched_between the contiguous charge transport_layer and the_supporting conductive_layer, the outer_surface of the charge transport layer_is normally charged_with a uniform charge of a_negative_polarity and the_supporting_conductive_layer is_utilized as an_anode.
As_more advanced,_complex,_highly sophisticated, electrophotographic copiers, duplicators and_printers_were developed, greater demands were placed on_the photoreceptor to meet_stringent_requirements for the production_of high quality images. For_example, the numerous layers found in_many modern_photoconductive imaging_members must be uniform, free of defects, adhere well to to_adjacent layers, and exhibit predictable electrical_characteristics within narrow operating_limits to_provide_excellent toner images_over_many thousands_of cycles. One type of multilayered photoreceptor_that has_been employed as a drum or_belt in electrophotographic imaging_systems_comprises a substrate, a conductive layer,_a charge blocking layer, an adhesive_layer, a charge generating layer,_and_a_charge transport layer. This photoreceptor_may also comprise additional layers such_as an overcoating_layer. Although excellent toner images may be_obtained_with multilayered photoreceptors, it has been_found_that the numerous layers limit the_versatility_of_the multilayered photoreceptor. For example,_these photoreceptors often comprise a metal_substrate having a roughened surface to avoid imagewise constructive_interference effects, known_as plywooding, that can occur_with_laser_exposure systems. This surface is coated with a typical film_forming hole_blocking layer such_as nylon, zirconium silane, and the like, to provide the_charge blocking function. These materials, especially nylons,_depend on water content to provide sufficient conductivity to bleed off_negative charge residual in the charge generating layer._Although many electrophotographic