CA1104866A - Imaging member containing a substituted n,n,n',n',- tetraphenyl-[1,1'-biphenyl]-4,4'-diamine in the chargge transport layer - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A photosensitive member having at least two electrically operative layers is disclosed. The first layer comprises a photo-conductive layer which is capable of photogenerating holes and injecting photogenerated holes into a contiguous charge transport layer. The charge transport layer comprises a polycarbonate resin containing from about 10 to about 75 percent by weight of:

Description

BACKGROUND OF THE INVENTION
r'his Invention relates in general to xerography and, more specifi-cally, to a novel photoconductive device and method of use.
In the art of xerography, a xerographic plate containing a photo-5 conductive insulating layer is imaged by first uniformly electrostaticallycharging its surface. The plate is then exposed to Q pattern of activating electromagnetic radiation such as light, which selectively dissipates the charge in the illuminated areas of the photoconductive insulator while leaving behind a latent electrostatic image in the non-illuminated areas. This latent 10 electrostatic image may then be developed to form a visible image by depositing finely divided electroscopic marking particles on the surface of the photoconductive insulating layer.
A photoconductive layer for use in xerography may be a homo-geneous layer OI a single material such as vitreous selenium or it may be a 15 composite layer containing a photoconductor and another material. One type of composite photoconductive layer used in xerography is illustrated by U.S.
- Patent 3,121,û06 to Middleton and Reynolds which describes a number of layers comprising inely divided particles of a photoconductive inorganic compound dispersed in an electrically insulating organic resin binder. In its present 20 commercial form, the bînder layer contains particles of zinc oxide uniformly dispersed in a resin binder and coated on a paper backing.
~; In the particular examples described in Middleton et al, the binder comprises a material which is incapable of transporting injected charge carriers generated by the photoconductor particles for any significant 25 distance. As a result, witll the particular material disclosed in Middleton et al ~ : :
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the photoconductor par-ticles must be, in substantlally continuous particle-to-particle contact throughou-t the layer in order to permit the charge dissipation required for cyclic operation.
Therefore, with the uniform dispersion of photoconductor particles described in Middleton et al, a relatively high volume concen-tration of photoconductor, about 50 percent by volume, is usually necessary in order to obtain sufficient photoconductor particle-to-particle contact for rapid discharge. However, it has been found that high photoconductor loadings in -the binder results in the physical continuity of the resin being destroyed, -thereby significan-tly reducing the mechanical properties of the binder layer. Systems with high photoconductor loadings are often characterized as having little or no flexibility. On the other hand, when the photoconductor concentration is reduced appreciably below about 50 percent by volume, the photo~induced discharge rate is reduced, making high speed cyclic or repeated imaging difficult or impossible.
U.S. Patent 3,121,007 to Middleton et al teaches another type of photoreceptor which includes a two-phase photoconductive layer comprising photoconductive insulating particles dispersed in a homogeneous photoconductive insulating matrix. The photoreceptor is in the form of a particulate photoconductive inorganic pigment broadly disclosed as being present in an amount from about 5 to 80 percent by weight. Photodischarge is said to be caused by the combination of charge carriers generated in the photoconductive insulating matrix material and charge carriers injected from the photoconductive pigment into the photoconductive insulating matrix.
U.S, Patent 3,037,861 to Hoegl et al teaches that poly(N-vinylcarbazole) exhibits some long-wave length U.V. sensi-tivity and suggests that i-ts spectral sensitivity can be extended .

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into the visible spec-trum by the addition of dye sensitizers. The Iloegl et ~1 pa-tent further suggests that other additives such as zinc oxide or titanium dio~ide may also be used in conjunction wi-th poly(N-vinylcarbazole). In the Hoegl et al patent, the poly(N-vinylcarbazole) is intended to be used as a photoconductor, with or without additive materials which extend its spectral sensitivlty.
In addition to the above, certain specialized layered structures particularly designed for xeflex imaging have been proposed. For example, U.S. Patent 3,165,405 to Hoesterey utilizes a two-layered zinc oxide bincler structure for reflex imaging. The Hoesterey patent utilizes two separate contiguous photoconductive layers having different spectral sensitivies in order to carry out a particular reflex imaging sequence. The Hoesterey device utilizes the properties of multiple photocon-ductive layers in order to obtain the combined advantages of the separate photoresponse of the respective photoconductive layers.
It can be seen from a review of the conventional com-posite photoconductive layers cited above, that upon exposure to light, photoconductivity in the layered structure is accomplished by charge transport through the bulk of the photoconductive layer, as in the case of vitreous selenium (and other homogeneous layered modifications). In devices employing photoconductive binder structures which include inactive eléctrically insulating resins such as those described in the Middleton et al, U.S. Paten-t 3,121,006, conductivity or charge transport is accomplished through high loadings of the photoconductive pigment and allowing particle-to-particle contact of the photoconductive particles. In the case of photoconductive particles dispersed in a photoconductive matrix, such as illustrated by the Middleton et al 3,121,007 patent, photoconductlvity occurs through the generation and transport of :

-: , , , : ~ . , char~e carriers in both the photoconductive matrix and the photoconductor pigment particles.
Although the above patents rely upon distinct mechanisms o~ discharge throughout the photoconductive layer, they generally suffer from com~on deficiencies in that the photocon-ductive surface during operation is exposed to the surrounding environment, and particularly i:n the case of repetitive xero-graphic cycling where these photoconducti,ve layers are susceptible to abrasion, chemical attack, heat and multiple exposure to light.
These effects are characterized by a gradual deterioration in the electrical characteristics of the photoconductive layer resulting in the printing out of surface defects and scratches, localized areas of persistent conductivity which fa.il to retain an electro-~ static charge, and high dark discharge.
:' 15 In addition to the problems noted above, these photo-receptors require that the photoconductor comprise either a hundred percent of the layer, as in the case of the vitreous selenium layer, or that they preferably contain a high proportion of photoconductive material in the binder configuration. rrhe requirements of a photoconductive layer containing all or a ma~or proportion of a photoconductive material further restricts the ' physical characteristics of the final plate, drum or belt in that the physical characteristics such as fle~ibility and adhesion of the photoconductor to a supporting substrate are primarily dictated by the physical properties of the photoconductor, and not by the ':' :
,. resin or matri~ material which is preferably present in a minor amount.
Another form of a composite photosensitive layer which ; has also been considered by the prior art includes a layer of ; ~30 photoconductive material which is covered with a realtive,ly thick . :
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plastic layer and coated on a supporting substrate.
U.S. Patent 3,041,166 to Bardeen describes such a configuration in which a transparer-t plastic material overlies a layer of vitreous selenium which is contained on a supporting substrate. In operation, the free surface of the transparent plastic is electrostatically charged to a given polarity. The device is then exposed to activating radiation which generates a hole-electron pair in the photoconductive layer. ~he electrons move through the plastic layer ancl neutralize positive charges on the free surface of the plastic layer thereby creating an electrostatic image. Bardeen, however, does not teach any specific plastic materials which will function in this manner, and confines his examples to structures which use a photoconductor material for the top layer.
French Patent 1, 577r 855 to Herrick et al describes a special purpose composite photosensitive device adapted for reflex exposure by polari2ed light. One embodiment which employs a layer of dichroic organic photoconductive particles arrayed in oriented fashion on a supporting substrate and a layer of poly(N-vinylcar-bazole) formed over the oriented layer of dichroic material. When charged and exposed to light polarized perpendicular to the orientation of the dichroic layer, the oriented dichroic layer and poly(N-vinylcarbazole) layer are both substantially transparent to the initial exposure light. When the polarized light hits the white background of the document being copied, the light is depolarized, reflected back through the device and absorbed by the dichroic photoconductive material. In another embodiment, the dichroic photoconductor is dispersed in oriented fashion through-out the layer of poly(N-vinylcarbazole).
The Shattuck et al, U.S. Patent 3~837~851~ discloses a ~ ,: , : . . ... :

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particular electrophotographic member having a charge generation layer and a separate charge transport layer. The charge transport layer comprises at least one tri-aryl pyrazoline compound. These pyrazoline compounds may be dispersed in binder material such as resins Icnown in the art.
Cherry et al, U.S. Patent 3,791,826 discloses an electrophoto-graphic member comprising a conductive substrate, a barrier layer, an inorganic charge generation layer and an organic charge transport layer comprising at least 2û percent by wei~ht trinitrofluorenone.
Belgium Patent 7fi3,540, issued August 26, 1971 discloses an electrophotographic member having at least two electrically operative layers.
The first layer comprises a photoconductive layer which is capable of photogenerating charge carriers and injecting the photogenerated holes into a contiguous active layer. The active layer comprises a transparent organic material which is substantially non-absorbing in the spectral region of intended use, but which is "active" in that it allows injection of photo-generated holes from the photoconductive layer, and allows these holes to be transported to the active layer. The active polymers may be mixed with interactive polymers or non-polymeric material.
Gilman, Defensive Publication of Serial Number 93,~49, filed November 27, 1970, published in 888 O.G. 707 on July 20, 1970, I~efensive Publication No. P888~013, U.S. Cl. 96/1.5, discloses that the speed of an inorganic photoconductor such as amorphous selenium can be improved by including an organic photoconductor in the electrophotographic element. For exarnple, an insulating resin binder may have TiO2 dispersed therein or it may ' ~ ~

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be a layer oE amorphous selenium. This la~er is overcoated with a layer of electrically insulating binder resin hav:ing an organic photoconductor such as 4,4'-diethylamino-2,2' dimethyltriphenyl-methane dispersed therein.
"~ulti-Active Photoconductive Element", Martin A. Berwick, Charles J. Fox and William A. Light, Research Disclosure, Vol. 133;
pages 38-43, May 1975, was published by Industrial Opportunities Ltd., Homewell, Havant, Hampshire, England. This disclosure relates to a photoconductive element having at least two layers comprising an organic photoconductor containing a charge-transport layer in electrical contact with an aggregate charge-generation layer. Both the charge-generation layer and the charge-transport layer are essentially organic compositions. The charge~
generation layer contains a continuous, electrically insulating polymer phase and a discontinuous phase comprising a finely-divided, particulate co-crystalline complex of (1) at least one polymer having an alkylidene diarylene group in a recurring unit and (2) at least one pyrylium-type dye salt. The charge-transport layer is an organic material which is capable of accepting and transporting injected charge carriers from the charge-generation layer. This layer may comprise an insulating resinous material having 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane dispersed therein.
Fox, U.S. Patent 3,265,496, discloses that N,N,N'N'-; 25 tetraphenylbenzidine may be used as photoconductive material in electrophotographic elements. This compound is not sufficiently soluble in the resin binders of the instant invention to permit a sufficlent rate of photo-induced discharge.
Straughan, U.S. Patent 3,312,548, in pertin~nt part, discloses a xe:rographic plate having a photoconductive insulating layer comprising a composition of selenium, arsenic and a halogen.
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The halogen may be present in amounts from abou~ 10 to 10,000 parts per million. This patent further discloses a xerographic plate having a support, a layer of selenium and an overlayer of a photoconductive material comprising a mixture of vitreous selenium9 arsenic and a halogen.
S The compound OI the instant invention is represented by the formula:

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X~ ~X

wherein X is selected from the group consisting of (ortho) CH3, (meta) CH3, (para) CH3, (ortho) Cl, (meta) Cl and (para) Cl, is dispersed in a polyearbonateresin in order to form a charge transport layer for a multi-layered device 15 comprising a charge generation layer and a charge transport layer. The ehargetransport layer must be substantially non-absorbing in the spectral region of intended use, but must be "active" in that it allows injection of photo-excited ~ holes from the photoconductive layer~ i.e., the charge generation layer, and - allows these holes to be transported through the charge transport layer.
Most organic charge transporting layers using active materials dispersed in organic binder materials have been found to trap charge carriers causing an unacceptable build-up of residual potential when used in a cyclic mode in electrophotographyO Also, most organic charge transporting materials known when used in a layered configuration contiguous to an amorphous 25 selenium eharge generating layer have been found to trap charge at the interface between the two layers. This results in lowering the potential differences between ths illuminated and non-illuminated regions when these structures are exposed to an image.

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This, i.n turn, lowers the print density of the end product, i.e., the electrophotographic copy.
In addition/ most of the organic transport materials known to date are found to undergo deterioration when exposed to ultraviolet radiation, e. g. U. V. emitted from corotrons, lamps, etc.
Another consideration which is necessary in the system is the glass transition temperature (Tg~. The (Tg) of the transpor~n~ L~yer has to be subs~antially higher than the normal operat,-ing temperatures. Many organic charge transporting layers using active materials dispersed in organic binder material have unacceptable low (Tg) at loadings of the active material in the organic binder material which is required for efficient charge transport. This result in the softening of the matrix of the layer andr in turn, becomes susceptible to impac~ion of dry developers and toners. Another unaccept-able feature of a low (T~) is the case of leaching or exudation of the active materials from the organic binder material result~
ing in degradation of charge transport properties from the ~ charge transport layer.
:: 20 Another consideration for the use of organic trans-port Iayers in electrophotography is the value of the charge carriers mobilities. Most of th,e organicsknown to date are deficient in this respect in that they set a limit to the cyclic speed of the system employing the same. ..
: 25 'It was found that one or a combination of compounds within the general formula:
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wherein X is selec-ted from the group consisting of (ort~o) CH3, (meta) CH3, (para) CH3, (ortho) Cl, (meta) Cl and (para) Cl dispersed in a polycarbonate resin transports charge very efficiently without any trapping when this layer is used con-tiguous with a generation laye:r and subjected to charge/lîghtdischarge cycles in an electrophotographic mode. There is no buildup of the residual potent:ial over many thousands of cycles.
The above described small molecules due to the presence of solubilizing groups, such as, methyl (CE13) or chlorine (Cl) are substantially more soluble in resin binders described herein whereas unsubstituted tetra phenyl benzidine, is not sufficiently soluble in the resin binders described herein for the intended purpose.
Furthermore, when the diamines of the instant invention dispers-ed in a polycarbonate binder are used as -transport layers contiguous a charge generation layer, there -~ is no interfacial trapping of the charge photogenerated in and injected from the generating layer. When subjected to ultraviolet radiation, no deterioration in charge transport was observed in these transport layers containing the sub-stituted N,N, N ' ,N' ,- tetraphenyl~ bipheny ~-4,4'-diamines of the instant invention.
Furthermore, diamines of t e instant lnvention dispersed in a polycarbonate binder were found to have sufficiently high ~g) even at hi~h loadings, thereby elimi-nating the pr~blems associated with low (Tg) as discussed above.
; None of the above-mentioned art overcomes the above-mentioned~pro]blems. Furthermore, none of the above-mentioned art discloses~specific d~u~e generating material in a separate layer which is overcoated with a charge-transport layer comprising a polycarbonate resin matrix material having dispersed therein the diamines of the instant invention.
The charge :
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transport material is substantially non-absorbing in the spectral region of intended use, but is "active" in that it allows injection of photogenerated holes from the charge generation layer and allows these holes to be transported therethrough. The charge-generating layer is a photoconductive layer which is 5 capable of photogenerating and injecting photogenerated holes into the contiguous charge-transport layer.
- It has also been found that when an alloy of selenium and arsenic containing a halogen is used as a charge carrier generation layer in a multilayered device which contains a contiguous charge carrier transport 10 layer, the member, as a result of using this particular charge generation layer, has unexpectedly high contrflst potentials as compared to similar multilayered members employing other generating layers. Contrast potentials are impor-tant characteristics which determine print density.
OBJ~CTS OF TlIE INVENTION
It is an object of an aspect of this invention to provide a novel imaging system.
It is an object of an aspect of this invention to provide a novel photoconductive device adapted for cyclic imaging which overcomes the above-noted disadvantages.

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~ t is an object of an aspect of this invention to provide a photoconductive member comprising a generating layer and a charge transport layer comprising a polycarbonate resin material having dispersed therein $~N ~X

10 wherein X is selected from the group consisting of (ortho) CEI3, (meta) CH3, (para) CH3, (ortho) Cl, (meta) Cl and (para) Cl. The chemical name of the above formula is N,N'-diphenyl-N,N'-bis-(alkylphenyl)-[l,l'-biphenyl]- 4,4'-di-amine wherein the alkyl is selected from the group consisting of ~ methyl, 3 methyl and 4 methyl or the compound may be N,N'-diphenyl-N,N' -bis(halo 15 phenyl)-[1,1'-biphenyl]-4,4'-diamino wherein the halo is selected from the group consisting of 2 chloro, 3-chloro and 4-chloro.
It is an object of an aspect of this invention to provide a novel imaging member capable of remaining flexible while still retaining its electri-cal properties after extensive cycling and exposure to the ambient, i.e., 20 oxygen, ultraviolet radiation, elevated temperatures, etc.
n is an object of an aspect of this invention to provide a novel imaging member which has no bulk trapping of charge upon extensive cycling.
SUMMARY OF THE INVENTIVN
The foregoing objects and others are accomplished in accordance 25 with this invention by providing a photoconductive member having at least two operative layers. The first layer comprises a layer of photoconductive material which is capable of photogenerating and injecting photogenerated holes in~o Q

, , contiguous or adjacent electrically active layer. The electrically active material comprises a polycarbonate resin material having dispersed therein from about 25 to about 75 percent by weight of one or more compounds having the gener~l formula:

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/ N ~ ~ N ~

X X
wherein X is selected from the group s~onsisting of (ortho) CH3, (meta) CH3, (para) CH3, (ortho) Cl, (meta) Cl and (para) Cl. The compound may be named N,N'-diphenyl~N,N'-bis(alkylphenyl)-[l,l'-biphenyl]-4,4'-diamine wherein the alkyl is selected from the group consisting of 2 methyl, 3 methyl and 4 methyl 15 or the compound may be N,N'-bis(halo phenyl)[l,l'-biphenyl]-4,4'-diamirle wherein the halo is selected from the group consisting of 2-chloro, 3-chloro and 4-chloro. The active overcoating layer, i.e., the charge transport layer, issubstantially non-absorbing to visible light or radiation in the region of intended use but is "active" in that it allows the injection of photogenerated 20 holes from the photoconductive layer, i.e., charge generation layer, and allows these holes to be transported through the active charge trnnsport layer to selectively discharge a surface charge on the surfaee of the active layer.
It was found that, unlike the prior art, when the diamines of the instant invention were dispersed in a polycarbonate binder this layer transports25 charge very efficiently without any trapping of charges when this layer is used contiguous a generator layer and sub~ected to charge/light discharge cycles in an electrophotographic mode. There is no buildup of the residual potential over ' ~ , :
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many thousands of cycles.
Furthermore, the transport layers comprising the diamines the instant invention dispersed in a polycarbonate binder were found to have sufficiently high (Tg) even at high loadings thereby eliminating the problems associated with low (Tg). The prior art suffers from this deficiency.
Furthermore, no deterioration in charge transport was observed when these transport layers containing the diamines of the instant invention dispersed in a polycarbonate binder were subjected to ultraviolet radiation encountered in its normal usage in a xerographic machine environment.
The prior art also suffers from this deficiency.
Therefore, when members containing charge trans-port layers comprising a polycarbonate resin material having the diamines of the instant invention are exposed to ambient conditions, i. e., oxygen, U.V. radiation~ etc., these layers remain stable and do not lose their electrical properties.
Furthermore, diamines of the instant invention do not crystallize and become insoluble in the electrically in-active resinous material into ~hich these materials wereoriginally dispersed. Therefore, since the diamines of the instant invention do not appreciably react with oxygen or are not affected by U.V. radiation, normally encountered in their normal usage in a xerographic machine environment, the charge transport layer comprising a polycarbonate resin material having diamines of the instant invention allow acceptable injection of photo-., . -.
' , genera-ted holes from the photoconductor layer, i.e., charge genera-tion layer, and allow these holes to be transported repeatedly through the active layer sufficiently to acceptably discharge a surface charge on the free surface of the active layer in order to form an acceptable electrostat:ic latent image.
As mentioned, the foregoing objects and others may be accomplished in accordance with this invention by providing a speci~ically preferred photoconductive member having at least two operative layers. The first layer being a most preferred specie which consists essentially of a mixture of amorphous selenium, arsenic and a halogen. Arsenic i5 present in amounts from about 0.5 percent to about 50 percent by weight and the halogen is present in amounts from about 10 to about 10,000 parts per million with the balance being amorphous selenium. This layer is capable of photogenerating and injecting photogenerated holes I-~ into a contiguous or adjacent charge transport layer. The charge ~-J' ~ p ~ ar b of ~ afe transport layer consists essentially of resinous material having dispersed therein from about 10 to about 75 percent by weight of the substituted N,N,N',N'-tetraphenyl-[1,1'-biphenyl]-4,4'-diamines of the instant invention.

"Electrically active" when used to define active layer 15 means that the material is capable of supporting the injection of photogenerated holes from the generating material and capable of allowing the transport of these holes thr~ugh the active layer in order to discharge a surface charge on the active layer~

"Electrically inactive" when used to describe the organic material which does not contain any substituted N,N,N',N'-tetraphenyl-[l,l'-biphenyl]-4,4'-diamines of the instant invention means that the material is not capable of supporting the ~; 30 injection of photogenerated holes from the generating material and is not capable of allowing the transport o~ these holes j:

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through the material.
It should be understood that the polycarbonate resinous material which becomes electrically active when it contains from about 25 to about 75 percent by weight of the diamine does not function as a photoconductor in the 5 wavelength region of intended use. As stated above, hole-electron pairs are photogenerated in the photoconductive layer and the holes are then injected into the active layer and hole transport occurs through this active layer.
A typical application of the instant invention involves the use of a layered configuration member which in one embodiment consists of a 10 supporting substrate such as a conductor containing a photoconduetive layer thereon. For e~ample, the photoconductive layer may be in the form of amorphous, vitreous or trigonal selenium or alloys of selenium such as selenium-arsenic, selenium-tellurium-arsenic and selenium-tellurium. A
charge transport layer of electrically inactive polycarbonate resinous material 1~ having dispersed therein from about 25 percent to about 75 percent by weight of the diamine is coated over the selenium photoconduetive layer. Generally, a thin interfacial barrier or blocking layer is sandwiched between the photoconductive layer and the substrate. The barrier layer may comprise any suitable electrically insulating material such as metallic oxide or organic 20 resin. The use of the polycarbonate containing the diamine allows one to take advantage of placing a photoconductive layer adjacent to a supporting substrate and protecting the photoconductive layer with a top surface which will allow for the transport of photogenerated holes from .
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the photoconductor, and at the same time f-lnction to physically proteet the photoconductive layer from environrslental conditions. This structure can then be imaged in the conventional xerographic manner which usually includes charging, optîcal projection exposure and development.
~s mentioned, when an alloy of selenium and arsenic containing a halogen of the instant invention is used as a charge carrier generation layer ina multilayered device which contains a contiguous charge currier transport layer, the member, as a result of using this particular charge generation layer has unexpectedly high contrast potentials as compared to similar multilayered members using different generator layer materials.

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A comparison is made between a 60 micron thick single layer photoreceptor member containing 64.5 percent by weight amorphous selenium, 35.5 percent by weight arsenic and 850 parts per million iodine and a multilayer member of the instant invention. The instant invention member 5 used in the comparison is a multilayered device with a 0.2 micron thick charge generation layer of 35.5 percent by weight arsenic, 64.5 percent by weight amorphous selenium and 850 parts per million iodine. This charge generation layer is overcoated with a 30 micron thick charge transport layer of MakrolonR, a polycarbonate resin, which has dispersed therein 40 percent by 10 weight N,NI-diphenyl-N,N'-bis(3-methylphenyl)-[2,2'-dimethyl-l,l'-biphenyl]-4,4'-diamine.
In general, the advantages of the improved structure and method of imaging will become apparent upon consideration of the following disclosure of invention, especially when taken in conjunction with the accompanying 15 drawings wherein:

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Fig. 1 is a schematic illustration of one embodiment of a device of the instant invention.
Fig. 2 illustrates a second embodiment of the device for the instant invention.
Fig. 3 illustrates a third embodiment of the device of the instant invention.
Fig. 4 illus-trates a fourth embodiment of the device of the instant invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Fig. 1 designates imaging member 10 in the form of a plate which comprises a supporting substrate 11 having a binder layer 12 thereon, and a charge transport layer 15 positioned over binder layer 12. Substrate 11 is preferably made up of any suitable conductive ma~erial. Typical conductors include ;

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aluminum, steel, brass, graphite, dispersed conductive salts, conductive polymers or the like. The substrate may be rigid or flexible and of any conventional thickness. Typical substrates include flexible belts or sleeves, sheets, webs, plates, cylinders and drums. The substrate or support may also comprise a composite structure such as a thin conductive layer such as aluminum or copper iodide, or g;Lass coated with a thin conductive coating of chromium or tin oxide. Particularly preferred are substrates of metalized polyesters, such as Mylar.
In addition, if desired, an electrically insulating substrate may be used. In this instance, the charge may be placed upon the insulating member by double corona charging techniques well known and disclosed in the art. Other modifi-cations using an insulating substrate or no substrate at all include placing the imaging member on a conductive backing member or plate and charging the surface while in contact with said backing member. Subsequent to imaging, the imaging member may then be stripped from the conductive backing.
Binder layer 12 contains photoconductive particles 13 ; 20 dispersed randomly without orientation in binder 14. The photoconductive particles may consist of any suitable inorganic or organic photoconductor and mixtures thereof. Inorganic materials include inorganlc crystalline photoconductive compounds and inorganic photoconductive glasses. Typical inorganic crystalline compounds include cadmium sulfoselenide, cadmium selenide, cadmium sulfide and mixtures thereof. Typical inorganic photoconductive glasses include amorphous selenium and selenium ~ alloys such as selenium-tellurium, selenium-tellurium-arsenic i~ and selenium-arsenic and mixtures thereof. Selenium may also be ~ 30 used in a crystalline form known as trigonal selenium. A method of , making a photosensitive imaging device utilizing trigonal selenium tn~ nu~r~
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comprises vacuum evaporating a thin layer o~ vitreous selenium onto a substrate, forming a relatively thicker layer of electrically active organic material over said selenium layer, followed by heating the device to an elevated temperature, e.g., 125C. to 210C., for a sufficient time, e.g., 1 to 24 hours, sufficient to convert the vitreous selenium to the crystalline trigonal form.
Another method of making a photosensitive member which u-tilizes trigonal selenium comprises forming a dispersion of finely divided vitreous selenium particles in a liquid organic resin solution and then coating the solution onto a supporting substrate and drying to form a binder layer comprising vitreous selenium particles contained in an organic resin matrix. Then the member is heated to an elevated temperature, e.g., 100C. to 140C. for a sufficient time, e.g., 8 to 24 hours, which converts the vitreous selenium to the crystalline trigonal form.
Typical organic photoconductive material which may be used as charge generators include phthalocyanine pigment such as the X-form of metal-free phthalocyanine described in U.S. Patent ` 3,357,989 to Byrne et al; metal phthalocyanines such as copper phthalocyanine; quinacridones available from DuPont under the tradename Monastral Red, Monastral Violet and Monastral Red Y;
substituted 2,4-diamino-triazines dlsclosed by Weinberger in U.S.
; Patent 3,445,227; triphenodioxazines disclosed by Weinberger in U.S. Patent 3,442,781; polynuclear aromatic quinones available from Allied Chemical Corporation under the tradename Indofast Double Scarletv Indofast Violet Lake B, Indofast Brilliant Scarlet and Indofast Orange.
Intermolecular charge transfer complexes such as a mixture of poly(N-vinylcarbazole~ (PVK) and trinitrofluorenone (TNF) may be used as charge generating materials. These materials `~ are capable of~injecting photogenerated holes into the transport materlal.

~22-One of the most preferred ernbodiments is a 0.2 micron thick charge generation layer of 35.5 percent by weight arsenic, 64.5 percent by weight amorphous selenium and 850 parts per rnillion iodine. This charge generation layer may be overcoated with a 30 micron thick charge transport 5 layer Oe MakrolonR, a polycarbonate resin, which has dispersed therein 40 percent by weight of a substituted N,N,N',N'-tetraphenyl~ biphenyl]-4,4'-diamine of the instant invention.
The above list of photoconductors should in no WQ~ be taken as limiting, but merely illustrative as suitable materials. The size of the 10 photocondllctive particles is not particularly critical; but particles in a size range of about 0.01 to 5.0 microns yield particularly satis~actory results.
Binder rnaterial 14 may comprise any electrically insulating resin such as those described in the above-mentioned Middleton et al, IJ.S. Patent 3,121,006. When using an electrically inactive or insulating resin, it is essential 15 that there be particle-to-particle contact between the photoconductive particles. This necessitates that the photoconductive material be present in an amount of at least about 10 parcent by volume o~ the binder layer with no limitation on the maximum amount of .

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photoeonductor in the binder layer. If the matrix or binder comprises an flctive material, the photoconductive material need only to comprise about 1 percent or less by volume of the binder layer with no limitation on the maximum amount of the photoconductor in the binder layer. The thickness of 5 the photoconductive layer is not critieal. Layer thicknesses from about 0.05 to 20.0 microns have been found satisfactory, with a preferred thickness of about 0.2 to 5.0 microns yielding good results.
Another embodiment is where the photoconductive material may be particles of amorphous selenium-arsenic-halogen as shown as particles 13 10 which may comprise from about 0.5 percent to about 50 percent by weight arsenic and the halogen may be present in amounts from about 10 to 10,000 parts per million with the balance being amorphous selenium. The arsenic preferred may be present from about 20 percent to about 40 percent by weight with 35.5 percent by weight being the most preferred. The halogen preferably 15 may be iodine, chlorine or bromine. The most preferred halogen is iodine. The remainder of the alloy or mixture is preferably selenium.
Active layer 15 comprises a transparent electrically inactive poly-carbonate resinous material having dispersed therein from about 25 to 75 percent bV weight of the dinmines detined above.

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,- . : :

.J~ 6 In general, the t~ickness of active layer 15 should be from about 5 to 100 microns, but thicknesses out-side this range can also be used.
The preferred polycarbonate resins for the trans-port layer have a molecule weight (Mw) from about 20,000 to about 120,000, more preferably from about 50,000 to about 120,000.
The materials most preferred as ~he electrical-ly inactive resinous material is poly(4,4l isopropylidene-diphenylene carbonate) with a molecular weight (~w) of from about 35,000 to about 40,000, available'as Lexan~ , 145 from General Electric Company; poly(4,4'-isopro-pylidene-diphenylene carbonate) with a molecular weight (Mw) of from about 40,000 to about 45,000, available as Lexan~ 141 from the General Electric Company; a poly-carbonate resin having a.molecular weigh.t.(Mw.) o~ from about 50,000 to about 120,000 available as Makrolon~
from Farbenfabricken Bayer A.G. and a pol.ycarbonate resin having a molecular weight (Mw) of from about 20lO00 to about 50,000 available as Merlon~ from Mobay Chemical Company.
In another embodiment of the instant invention, ::
~ the ~. . .

. .
' I
`~: `:
:
~, , :

: ~ -25/26~

:::: : : :

..

structure of Fig. 1 is modified -to insure that the photoconductive particles are in the Eorm of continuous chains through the thickness of binder layer 12. This embodiment is illustrated by Fig. 2 in which the basic struct:ure and materials are the same as those in Fig. 1, except the phot:oconductive particles are in the form of continuous chains. Layer 14 of Fig. 2 more specifically may comprise photoconductive materials in a multiplicity of interlocking photoconductive continuous paths through the thickness of layer 1~, the photoconductive paths being present in a volume concentration based on the volume of said layer, of from about 1 to 25 percent.
A further alternative for layer 14 of Fig. 2 comprises photoconductive material in substantial particle-to-particle contact in the layer in a multiplicity of interlocking photocon-ductive paths through the thickness of said member, the photocon-ductive paths being present in a volume concentration, based on the volume of the layer, of from about 1 to 25 percent.
Alternatively, the photoconductive layer may consist entirely of a substantially homogeneous photoconductive material such as a layer of amorphous selenium, a selenium alloy or a powder or sintered photoconductive layer such as cadmium sulfo-selenide or phthalocyanine. This modification is illustrated by Fig. 3 in which the photosensitive member 30 comprises a sub-strate 11, having a homogeneous photoconductive layer 16 with an overlylng active organic transport layer 15 which comprises an electrically inactive organic resinous material having dispersed therein from ahout ~ttto about 75 percent by weight of the suh-.
stituted N,N,N',N'-tetraphenyl-[l,l'-biphenyl~-4,4'-diamines of the instant invention.
~ ` 30 Another modification of the layered configuration `~ ~ descrlbed in Pigs. 1, 2 and 3 include the use of a blocking layer .. .
' ~ -27-,: :

17 at the substrate-photoconductor interface. This configuration is illustrated by photosensitive member 40 in ~ig. 4 in which the substrate 11 and photo-sensitive layer 16 are separated by a blocking layer 17. The blocking layer functions to prevent the injection of charge carriers from the substrate into 5 the photoconductive layer. Any suitable blocking material may be used.
Typical materials include nylon, epoxy and aluminum oxide.
It should be understood that in the layered configurations described in Figs. 1, 2, 3 and 4, the photoconductive material preferably is selected from the group consisting of amorphous selenium, trigonal selenium, selenium alloys 10 selected from the group consisting essentially of selenium-tellurium, selenium-tellurium-arsenic, and selenium-arsenic and mixtures thereof. One of the preferred photoconductive materials is trigonal selenium.

:

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~ -28-`:
- , .. .

Active layer 15, as described above, is non-absorbin~ to light in the wavelength region of use to generate carriers in the photoconductive layer.
This preferred range for xerographic utility is f'rom about 4,000 to about 8,000angstrom UIlitS. In addition, the photoconductor should be responsive to all wavelengths from ~,000 to 8,000 angstrom units if panchromatic responses are required. All photoconductor-active material combination of the instant invention results in the injection and subsequent transport of holes across the physical interface between the photoconductor and the active material.
The reason for the requirement that active layer 15, i.e., charge 10 transport layer, should be transparent is that most of the incident radiation is utilized by the charge carrier generator layer f'or ef'ficient photogeneration.

:

`: :

~. -29-The active transport layer which is employed in conjunction with the photoconductive layer in the instant invention is a material which is an insulator to the extent that the electrostatic charge placed on said active transport layer is not eonducted in the absence oE illumination, i.e., with a 5 rate sufficient to prevent the formation and retention of an electrostatic latent image thereon.
In general, the -thickness of the active layer preferably is from about 5 to lO0 microns, but thicknesses outside this range can also be used.
The ratio of the thickness of the active layer, i.e., charge transport layer, to lO the photoconductive layer, i.e., charge generator layer, preferably should be maintained from about 2:1 to 200:1 and in some instances as great as 400:1.
The following examples further specifieally define the present invention with respect to a method of making a photosensitive member.

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The percentages are by weight unless otherwise indicated. The examples below are intended to illustrate various preferred embodiments of the instant invention.
EX~MPLE I
Preparation of N,N'-diphenyl-N,N'-bis(3-methyl phenyl)-~l,l'-biphenyl~-4,4'-diamine: In a 5000 milliliter, round bottom, 3 necked flask fitted with a mechanical stir-rer and blanketed with argon, is placed 336 grams (1 mole) of N,N'-diphenylbenzidine, 550 grams (2.5 moles) of m-iodoto luene, 550 grams (4 moles) potassium carbonate (anhydrous) and 50 grams of copper bronze catalyst and 1500 ml dimethyl-sul~oxide (anhydrous). The heterogeneous mixture is reflux-ed for 6 days. The mixture is allowed to cool. 2000 ml of benzene is added. The dark slurry is then filtered. The filtrate is extracted 4 times with water~ Then the filtrate is dried with magnesium sulfate and filtered. The benzene is taken off under reduced pressure. m e black product is column-chromatographed using Woelm neutral alumina. Color-less crystals of the product are obtained by recrystallizat-ing the product fron n-octane. The melting point is 167 -169C. The yield is 360 grams (65%). ~
~ - Analytical ~alculation for C38H3~N2: C,88.34;H, `~ 6.24;N,5.37. Found: C,88.58;H,6.21;N,5.37.
;~ NMR (CDC13) B 2.23(s,6,methyl),6.60-7.47 ppm (m, 26, aromatics).
EXAMPLE II
A photosensitive layer structure similar to that ~` illustrated in Fig. 3 comprises an aluminized Mylar~ sub-~: :
strate, having a 1 micron layer of amorphous selenium over the substrate, and a 22 micron thick layer of a charge transport materiaI comprising 25 percent by weight of N,N' ; --diphenyl-N,N'-bis(3-methylphenyl)~ biphenyl7-4,4'-~".g ~ :

. . . . . . ...

f~6 d.iamine and 75 percent by weight bisphenol-A-polycarbonate (Lexan~ 145, obtained from General Electric Company) over the amorphous selenium layer. The member is prepared by the following technique:
A 1 micron layer of vitreous selenium is formed over an , : , '.

.

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~: :

-31a-:,. . . .
: ~; ' ' . ' . .

~ ~f~

aluminized Myla ~ substra-te by conventional vacuum deposition -technique such as -those disclosed by Bixby in U.S. Patent

2,753,278 and U.S. Patent 2,970,906.
A charge transport layer is prepared by dissolving in 135 grams of methylene chloride, 3.34 grams of ~ diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4' diamine as pre-pared in Example I and 10 grams of bisphenol-A-polycarbonate (Lexar~ 145, obtained from General Electric Company). A layer of the above mixture is formed on the vitreous selenium layer using a Bird Film Applicator. The coating is then vacuum dried a-t 40C. for 18 hours to form a 22 micron thin dry layer of charge transport material.
; The above member is then heated to about 125C. for 16 hours which is sufficient to convert the vitreous selenium to lS the crystalline trigonal form.
The plate is tested electrically by negatively charging the plate to a field of 60 volts/micron and discharging it at a wavelength of 4,200 angstrom units at 2 x 1012 photons/cm2 seconds.
The plate exhibits satisfactory discharge at the above fields and is capable of use in forming visible images.
EXAMPLE III
A photosensitive layer structure similar to that illustrated in Example I comprising an aluminized MyIar sub-strate, having a 1 micron layer of trigonal selenium over the substrate, and a 22 micron thick layer of charge transport layer comprising 50 percent by weight of N,N' diphenyl-N,N'-bis(3-methylphenyl)-[l,l'-biphenyl]-4,4'-diamine and 50 percent by weight bisphenol-A-polycarbonate (Lexan~ 141, obtained from i General Electr:ic Company) is overcoated onto the trigonal selenium layer The member is prepared by the following techni~ue:
A 1 micron layer of amorphous selenium is vacuum - : .
. .

~f~

evaporated on a 3 mil aluminum substrate by conventional vacuurn deposition technique such as those disclosed by Bixby in U.S.
Patents 2,753,278 and 2,970,906. Prior to evaporating the amorphous selenium onto the substrate, a 0.5 micron layer of an epoxy-phenolic barrier layer is formed over the aluminum by dip coating. Vacuum deposition is carried out at a vacuum of 10 6 Torr while the substrate is maintained at a temperature of about 50C. during the vacuum deposition. A 22 micron thick layer of charge transport material comprising 50 percent by weight of N,N'-diphenyl-N,NI-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine and 50 percent by weight of poly(4,4l-isopropylidene-diphenylene carbonate) having a (Mw) of about 40,000 (available as Lexan~ 141 from General Electric Company) is coated over the amorphous selenium layer.
The charge transport layer is prepared by dissolving ; in 135 grams of methylene chloride, 10 grams of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine and 10 grams of poly(4,4'-isopropylidene-diphenylene carbonate) (Lexa ~ 141, having a (Mw) of about 40,000 obtained from General Electric Company). A layer of the above mixture as mentioned above is ; formed on the amorphou~ selenium layer by using a Bird Film Applicator. The coating is then dried at 40C. for 18 hours to form a 22 micron thick dry layer of charge transport material.
The amorphous selenium layer is then converted to the crystalline trigonal form by heating the entire device to 125C. and main-taining this temperature for about 16 hours. At the end of 16 hours, the device is cooled to room temperature. The plate is tested electrically by negatively charging the plate to fields of 60 volts/micron and di5charging them at a wavelength of 4,200 angstroms at 2 x 1012 photons/cm2 seconds. The plate exhibits satisfactory discharge at the above fields, and is capable of use in forming excellent visible images.

'' , EXAMPLE IV
. _ A photosensitive layer structure similar to that illustrated in Fig. 3 comprises an aluminized Myla ~ substra-te, having a 0.2 micron layer of amorphous selenium-arsenic con-taining a halogen over the substrate, and a 30 micron thick layer of a charge transport material comprising 25 percent by weight of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1' biphenyl]-4,4'-diamine and 75 percent by weight bisphenol-A-polycarbonate (Lexan~ 145, obtained from General Electric Company) over the amorphous selenium-arsenic-halogen layer.
The member is prepared by the following technique:
A mixture of about 35.5 percent by weight of arsenic and about 64.5 percent by weight of selenium and about 850 parts per million (ppm) of iodine are sealed in a Pyrex~ vial and reacted at about 525C. for abou-t 3 hours in a rocking furnance.
The mixture is then cooled to abou-t room temperature, removed from the Pyrex~ vial and placed in a quartz crucible within a bell jar. An aluminum plate is supported about 12 inches above the crucible and maintained at a temperature of about 70C.
The bell jar is then evacuated to a pressure of about 5 x 10 5 torr and the quartz crucible is heated to a temperature of about 380C. to evaporate the mixture onto the aluminum plate. The crucible is kept at the evaporation temperature for approximately 30 minutes. At the end of this time the crucible is permitted to cool and the finished plate is removed from the bell jar.
A charge transport layer is prepared by dissolving in ,~
135 grams of methylene chlorine, 3.34 grams of N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine as pre~
pared in Example I and 10 grams of bisphenol-A-polycarbonate (Lexan~ 145, obtained from General Electric Company). A layer of the above mixture is formed on the vitreous selenium-arsenic-

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iodine layer using a Bird Film Applicator. The coating is then vacuum dried at 80C. for 18 hours to form a 30 micron thin dry layer of charge transport mater:ial.
The plate is tested electrically by negatively charging the plate to a field of 60 volts/micron and discharging it at a wavelength of 4,200 angstrom un:its at 2 x 1012 photons/cm2 seconds.
The plate exhibits satisfactory discharge at the above fields ~a~bJe and is e~ of use in forming vis.ible images.

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SllPPLEMENTARY DL ~SCL~"SURE
In the prlncipal disclc~ure the "X" substituent attached to two of the phenyl groups of the charge transport compound was defined as being selected from the group consist-ing of (ortho) CH3, (meta) CH3, tpara) CH3, ~ortho) Cl, (meta) Cl and (para) Cl.
It has now been discovered that this "X" substituent should be more broadly defined, so that the compound of the instant invention is represented by the formula:

.~ @~ ' .~
/ N ~ N ~

' X/Ç~ ~ ~X' wherein X is selected from the group consisting of an alkyl group having from 1 to about 4 carbon atoms (e.g. methyl, ethyl, ~- propyl, isopropyl, isobutyl, tert-butyl, n-butyl, etc.) and chlorine in the ortho, meta or para position, and it is dis-persed in a polycarbonate resin in order to form a charge transport layer for a multi-layered device comprising a charge generation layer and a charge transport layer. The charge transport layer must be substantially nonabsorbing in the spectral region of intended use, but must be "active" in that it allows injection of photoexcited holes from the photo~
conductive layer, i.e., the charge generation layer, and allows these holes to be transported through the charge trans-port layer.
Thus, in accordance with this supplementary dis-closure, the principal disclosure of this application should be construed with the compound of the instant invention , bein~ represented by the formula indicated in the im~diately preceeding paragraph.
Thus, in accordance with one aspect of the instant invention, there is provided an imaging member comprising a charge generation layer comprising a layer of photoconductive material and a contiguous charge transport layer.of a poly-carbonate resin material having a molecular weight of from about 20,000 to about 120,000 having dispersed therein from about 25 to about 75 percent by weight of one or more compounds .
having the general formula:

N ~ ~

X ~ . ~ X
; .
, ~ .
: wherein X is selected from the group consisting of an alkyl group, having from 1 to about 4 carbon.:atoms and chloride, said photoconductive layer exhibiting the capability of photogenera-tion of holes and injection of said holes and said charge transport layer being substantially nonabsorbing in the spectral region at which the phstoconductive layer generates and injects photogenerated holes but being capable of supporting the injec-tion of photogenerated holes from said photoconductive layer :~ 25 and transporting said holes through said charge transport layer.

: ~ : :
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:
, ;~ , :~ -37-The following examples further specifically define the present invention with respect to a methocl of making a photosensitive mernber. The precentages are by ~eight unless otherwise indicated. The examples below are intended to illustrate various preferred lembodiments of the instant invention.
EXAMPLE V
Preparation of N,N' diphenyl-N,N'bis(4-methylphenyl)-[1,1'-bi-phenyl~ -4~4'-diamine.
A 500 ml, three necked, round bottom flask, equipped with a magnetic stirrer and purged with argon, was charged with 20 grams of p,p'-diiodo-biphenyl (0.05 mole~, 18.3 grams of p--tolyphenyl-amine (0.1 mole), 20.7 grams potassium carbonate (anhydrous) (0.15 mole), 3.0 grams of copper powder and 50 mls of sulfolane (tetrahydrothiophene-l,l-dioxide). The mixture was heated to 220-225C for 24 hours, allowed to cool to approximately 150C
and 300 mls of deionized water was added. The heterogeneous mixture was heated to reflux while vigorously stirring. A light tan oily precipitate was formed in the flask. The water was decanted. Then 300 mls of water was added and the water layer was again decanted. 300 mls of methanol was added and the mixture was refluxed to dissolve any unreacted starting materials.
`, The solids were filtered off, added to 300 mls of n-octane and heated to a reflux temperature of 125C. The solution was filtered through 100 grams of neutral Woelm alumina to give a pale yellow filtrate. The solution was again filtered through lOO grams of neutral Woelm alumina to yield a colorless filtrate and was allowed to cool yielding colorless crystals of the intended compound having a M.P. of lG3-164 C.
Analytical Calculatlon for C381132N2: C, 88.34; 11, 6.24; M, 5.37 Found: C! 88.49i H, 6.44; N, 5.28.
~ NMR (CDC13)~2.30 (s,6,methyl~; 6.93-7.56 ppm (m,26, aromatics).
~: :

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EXAMPLE Vl Preparation of photoreceptor device employing_the compound_of Example_V.
One gram of N, N'-diphenyl-N,N'-bis(4-methylphenyl)-[1,1'-bi-5 phenyl]-4,4'-diamine was dissolved in 13.5 grams of methylene chloride containing 1.0 gram of Makrolon(~), a polycarbonate, to form a 50 percent by weight solution of the diamine in the polycarbonate.
A generation layer was fabricated by vacuum evaporating a 0.5 micron thick amorphous selenium layer on an aluminum substrate by the 10 technique referred to in Example ILI. The methylene chloride-polycarbonate solution of the diamine was applied, using a Bird Film Applicator, to the generation layer in an amount such that it provided a dried thickness of about 25 microns after being subjected to a vacuum at 40C for 48 hours.
This member was xerographically tested by negatively charging it 15 in the dark to about -1500 volts; the dark decay was about 250 volts in 1.5 seconds~ and the member was then exposed to a flash of activating radiation of wavelength of 4330 angstrom units and energy of 15 ergs/cm2 for about 2 microseconds duration. The member completely discharged to zero volts almost instantaneously, i.e. in about 20 milliseconds. This rapid xerographic 20 discharge characteristic and the physical quality of the transport layer (smoothness, homogenity, transparency) make for ideal use in a fast, cyclic xerographic print mode.
EXAMPLE VII
Preparation of N N N' N'-tetraphenyl-~l,l'-bi~henyl]-4,4'diamine.
? ~ ~
25 (This compound is disclosed in Fox U.S. 3,265,496.) A 500 ml three necked round bottom flask equipped with a magnetic stirrer and purged with argon was charged with 20 grams p,p'-diiodo biphenyl (0.05 mole), 16.9 grams diphenylamine (0.1 mole), 20.7 grams potas-sium carbonate (anhydrous) (0.15 mole), 3 grams copper and 50 mls sulfolane 30 (tetrahydrothiophene-l,l-dioxide). The mixture was then heated to 220-225C

'~.
. .
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for 24 hours, allowed to cool to approxima~ely 151)C and 300 mls of deionized water was aclded. The heterogeneous m ixture was heated to reflux while vigorously stirring. A dark grey almost solid precipitate was formed. The water was decanted. Then 300 mls of l,vater was added and the water layer was again decanted. 300 mls of methanol was added and the mixture was refluxed while stirrin~ to remove unreacted starting materials. The solids were filtered off, dissolved in 300 mls of benzene and refluxed until the vapor temperature reached 80C. The solution was filtered while hot through 75 grams neutral Woelm alumina to give an orange/yellow filtrate. 200 mls of 10 ethanol was added and the solution allowed to cool. ~n orange crystalline solid material was filtered off and dissolved in 3D0 mls of ben~ene and column chromatographed using neutral Woelm alumina (500 grams) with benzene as the eluent. A colorless product was collected and extracted with 300 mls of acetone to yield colorless fine crystals with a M.P. of 230-231 C
Analytical Calculation for C36H28N2: (~, 88.;, Found: C, 88.79; H 5.89; N, 5.43.
NMR (CDC13)~6.91-7.49 (m, aromatics).
EXAM LE VIII
Preparation of photoreceptor devices employing the compound of 20 Example VII.
` Two separate combinations were made of this compound, i.e. N, N3N',N'-tetraphenyl-[l,l'-biphenyl]-4,4'-diamine with a methylene chloride solution of Makrolor~polycarbonate. The first combination produced a 15 percent by weight solution of this compound in the polycarbonate after 25 removal of the methylene chloride, i.e. 0.177 gram of the compound of Example VII in 1.0 gram of the polycarbonate. This was the maximum amount that could be dissolved in the polycarbonate.
The seeond combination produced a dispersion or incomplete solu-tion o~ 20 percent by weight of the compound in the same polycarbonate after 30 removal of the methylene chloride, i.e. 0.25 gram of the compound in 1.0 ~ram ,~

. . ' ' - ' ' - . ': . . ' of the polycarbonate. Transport layers coated from this dispersion showed numerous white areas greater than 1 micron in size. These ~Nhite areas indicate that the compound of U.S. 3,265,~196 crystallized from the matri2~.
Using the 15 and 20 percenl; by weight material respectively, two photoreceptor devices were prepared as in Example VI.
The member containing the 15 percent by weight of the Fox et al compound was negatively charged to about -1700 volts. It had a dark decay of about 125 volts in 1.5 seconds. The charged member was exposed to a flash of activating radiation for about 2 microseconds duration using a light wave 10 length of 4330 angstrom units with an energy of 15 ergs/cm2.
This member discharged at the following rate:
after 0.25 seconds discharged to about 900 volts;
after 0.50 seconds discharged to about 600 volts;
after 0.75 seconds discharged to about 500 volts;
after 1.00 seconds discharged to about 400 volts;
after 1.25 seconds discharged to about 360 volts;
after 1.50 seconds discharged lo about 290 volts;
after 1.75 seconds discharged to about 280 volts;
after 2.00 seconds discharged to about 260 volts;
after 4.00 seconds discharged to about 160 volts.
The nature of this xerographic curve precludes use of this device in a practical, high speed, cyclic xerographic device.
The member containing the 20 percent by weight of the compound ~- of U.S. 3,265,496 was negatively charged to about -1425 volts and the dark 25 decay was about 150 volts in about 1.0 seconds. This charged member was exposed to a flash of activating radiation of wavelength of 4300 angstrom units and energS7 of 15 ergs/cm2 for about 2 microseconds duration. This member discharged at the following rate:
after 0.25 seconds discharged to about 270 volts;
after û.5~ seconds discharged to about 195 volts, - , ~; . . , :, .. , -:,, - . . . : .
.

after 0.75 seconds dischargecl to about 180 volts;
after 1.00 seconds diseharged to about 150 volts;
after 1.25 seconds discharged to about 140 volts;
after 1.50 seconds dischargecl to about 130 volts;
after 1.75 seconds dischargecl to about 120 volts;
after 2.00 seconds discharged to about 120 volts;
after 4.00 seconds discharged to about 100 volts.
While the shape of this curve is improved over that of the 15 percent by weight member, it still indicates that the member is unacceptable for use in a practical, fast, cyclic xerographic device. Moreover, the heterogeneous nature of the transport layer, results in extremely poor xerographic print quality because of surface and bulk defects causing substan-tial loss of transpareney, excessive scattering of incident light, loss of mechanical strength, loss of resolution and excessive print defects.
~ EXAMPLE IX
Preparation of N,N'-diphen~l-N,N'-bis(2 meth~lphenyl)-[l.l'-bi-phen~4,4l-diamine.
Into a 250 milliliter, round bottom9 3 neck flask fitted with a mechanical stirrer, thermometer with temperature controller and a source of 20 argon are placed 804 grams of N,N7-diphenyl-[l,l'-biphenyl]-4,4'-diamine ~- (0.025 moles), 16.3 grams of 2-iodotoluene (0.075 moles), 7.5 grams copper bronze and 25 milliliters of a mixture of C13-C15 aliphatic hydrocabrons, i.e.
Soltrol6~170, from Phillips Chemical Company. The contents of the flask are heated to 190 C with stirring for a period of 18 hours. Using a water aspirator, 25 the ex~ess~2-iodotoluene is removed by vacuum~ distillation. The product is : ~ :
isolated by the addition of 200 milliliters of n-octane and hot filtration to remove the inor~ganic solids. The deep orange filtrate is column chromato-graphed using Woelm oeutral alumina with cyolohexane/benezene in a 3:2 ratio - as the eluent. ~ The resulting oil is recrystallized from n-octane to yield 30 colorless crystals of the intended compound having a melting point of 148-150 C.
, :
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Analytical Calculation for C38H32 N2: C, 8 Found: C, 88.63; H, 6.25; N, 5.22.
NMR (CDC13) 2.04 (s, 6, methyl); 6.84-7.44 ppm (m, 26, aromatics).
EXAMPLE X
Preparation of N,N'-diphenyl-N,N'-bis(3~ethYlphenyl)-[l~l'-bi-phe~yl] -4,4'-diamine.
Into a 250 milliliter 3 necked round bottom flask equipped with a mechanical stirrer, thermometer with temperature controller and a source oi~
argon are placed 8.4 grams of N,N'-diphenyl-[l,l'-biphenyl]-4,4'-diamine 10 (0.025 moles), 13.8 grams of powdered potassium carbonate (0.1 moles), 17.4 grams of 3-ethyl iodo-benzene (0.075 moles), 7.5 grams of copper bronze and 25 milliliters of a mixture of C13-C15 aliphatic hydrocarbons, i.e. Soltrol~3)170, from Phillips Chemical Company. The contents of the flask are heated to l90~C for 18 hours. Using a water aspirator, the excess 3-ethyl iodobenæene is 15 removed by vacuum distillation. The product is isolated by the addition o~ 20milliliters of n-octane and hot filtration to remove the inorganic solids. The deep orange filtrate is eolumn chromatographed using Woelm neutral alumina with cyclohexane/benzene in the ratio of 3:2 as eluent. The resulting oil is recrystallized from methanol and dried to yield pale yellow crystals of the 20 intended product having a melting point of 62-69C.
Analytical Calculntion for C40H36N2: C, 88.20; H, 6.66; N, 5.14.
Found: C, 88.37; H, 6.71; N, 5.03.
; NMR (CDC13) 1.17 (t,6, methyl); 2.65 (q, 4, methylene); 6.92-7.53 ppm (m, 26, aromatics).
EXAMPLE XI
Preparation of N,N'-diphenyl-N,N'-bis(4-ethylphenyl)-[1,1'-bi-phenyl~-4,4'-diamine.
Into a 250 milliliter 3 neclced round bottom flask equipped with a mechanical stirrer, thermometer with temperature controller and a source of ; 30 argon are placed 8.4 grams of N,N'-diphenyl-[l?l~-biphenyl]-4,4'-diamine ::

: : :
,. ~ . . .
~: . . . : : , (0.025 moles), 13.8 grams of powdered potassium carbonate (0.1 moles), 17.4 grams of 4-ethyl iodobenzene (0.075 moles), 7.5 grams of copper bronze and 25 milliliters of a mixture of C13-C15 aliphatie hydrocarbons, i.e. Soltrol~170 from Phillips Chemical Company. Thle contents of the flask are heated to 190 C for 18 hours. Using a water aspirator, the excess 4-ethyl iodobenzene is removed by vacuum distillation. The product is isolated by ~he addition of 20U
milliliters of n-octane and hot filtration to remove the inorganic solicls. The deep orange filtrate is column chromatographed using Woelm neutral alumina with cyclohexane/benzene in a ratio of 3:2 as eluent. The resulting oil is 10 recrystallized from octane to yield pale yellow crystals of the intended product having a melting point of 149-151 C.
Analytical Calculation for C40H36N2: C, 88.20; M, 6.66; M, 5.14.
Found: C, 88.27; H, 6.72; N, 4.98.
NMR (CDC13)~1.22 (t,6, methyl); 2.60 (q, 4, methylene); 6.86-7.64 15 ppm (m, 26, aromatics).
EXAMPLE XII
Preparation of N,N~-diphenyl-N,N'-bis(4-n-butylphenyl)-~1,1'-bi-phenyl]-4,4'-diamine.
Into a 250 miIliliter 3 neck round bottom flask equipped with a 20 mechanical stirrer, thermometer with temperature controller and a source of argon are placed 8.4 grams of N,N'-diphenyl-[l,l'-biphsnyl]-4,4'-diamine (0.025 moles), 13.8 grams of powdered potassium carbonate (0.1 moles), 19.5 grams of 4-n-butyl iodobenzene (0.075 moles~ 7.5 grams copper bronze and 25 milliliters of C13-C15 aliphatic hydrocarbons, i.e. Soltro~) 170, from the 25 Phillips Chemical Company. The contents of the flask are heated to l90~C
with stirring for a period of 18 hours. The product is isolated by the addition of 200 milliliters of n-octane and hot filtration to remove the inorganic solids.
The deep orangle filtrate is column chromatographed using Woelm neutral alumina with cyclohexane/benzene in a ratio of 3:2 as eluent. The resulting 30 viscous oil is recrystallized frorn octane to yield pale yellow crystals of the intended product having a melting poinl of 130-132 C.

_a~4_ ~ ~, '. ` ~.

Analytical Caleulalion for C4~H44N2: C, 87.96; fl, 7.38; N, 4.66.
Found: C, 88.34; H, 7.30; N, 4.41.
NMR (CDC13)J0.93 (t, 6, methyl); 1.15-1.78 (m, 8, methylene) 2.57 (t, 4, methylene)~ 6.50-7.58 ppm (m, 26, aromaties).
EXAMPLE XIII
Preparation of _ N,N'-dipllen~-bis(3-chlor~phenyl)-[1.1'-bi-phenyl]-4,4'-_iamine.
Into a 250 millimeter of three necked round bottom elask equipped with a mechanical stirrer, thermometer with temperature controller and a 10 source of argon gas are placed 3.4 grams of N,N'-diphenyl-[l,l'-bi-phenyl]-4,4'-diamine (.01 moles), 5.6 grams of potassium carbonate (.04 moles), 9.6 grams of 3-chloroiodobenzene (.04 moles) and 0.5 grams of copper powder. The contents of the flask are heated with stirring for a period of 24 hours. Using a water aspirator, the excess 3-chloroiodobenzene is removed by 15 vacuum distillation. The product is isolated by the addition of 200 milliliters n-octane and hot filtration to remove the inorganic solids. The deep orange filtrate is column chromatographed using Woelm neutral alumina with cycl~
hexane/benzene as eluent (3/2). The resulting oil is recrystallized from n-octane to yield colorless crystals of the intended product having a melting 20 point of 130-132 C .
EXAMPLE XIV
Preparation of_ N,N'-diphenyl-N?N'-bis(4-chlorophenyl)-[1,1'-bi-phenyl] ~4,4'-diamine.
Into a 250 mllliliter three necked round bottom ilask equipped with 25 a mechanical stirrer, thermometer with temperature controller and a source of non-oxidizing gas are placed 3.4 grams of N,N'-diphenyl-[l,it-bi-phenyl]-4,4'-diamine (.01 mole)~ 5.6 grams potassium carbonate (.û4 rnole), 9.6 grams of 4-chloroiodobenzene ~.04 mole) and 0.5 grams copper powder the contents of the flask are heated with stirring for a period of 24` hours. Using a ~ ~ 30 water asplrator, the excess 4-chloroiodobenzene Is removed by vacuum :: :

.

. ~. .

distillation. The prodllct is isolated by the addition of 200 milliliters n-octane and hot eiltration to remove the inorganic solids. The deep orange filtrate is column chromatographed using W oelm neutral alumina with cyclo-hexane/benzene as eluent (3/2). The resulting oil is recrystallized from n-octane to yield colorless crystals of the intended product having a melting point of 147-149 C.
EXAMPLE XV
Six photoreceptor devices were prepared employing the compounds prepared in Examples IX-XIV in the transport layers. Six solutions were 10 prepared, each containing 1 gram of Makrolon~;), a polycarbonate, dissolved in 13.5 grams of methylene chloride. Into each solution was dissolved 1 gram of the compounds prepared in Examples IX-XIV to form a 50 percent by weight solid solution of the compound in the polycarbonate after the methylene chloride is removed.
On six, two-inch square aluminum substrates, a 0.5 micron thick - layer of amorphous selenium was evaporated. The polycarbonate solutions of the compound of Examples IX-XIV were deposited over the selenium by the use of a Bird Film Applicator and vacuum dried at 40 C for 24 hours to yield a 25 micron layer.
Electrical testing of ~hese plates as illustrated in Example V~
showed that the charge transport in these structures was comparable to the photosensitive structures of Examples II, III, IV nnd VI. Using a Xerox Corporation D~odel D Processor, each plate produced excellent xerographic copies.
The invention has been described in detail with particular refer-ence to prefeirred embodiments thereof but it u7ill be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.
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Claims

WHAT IS CLAIMED IS:

1. An imaging member comprising a charge generation layer comprising a layer of photoconductive material and a contiguous charge transport layer of electrically inactive polycarbonate resin having dispersed therein from about 10 to about 75 percent by weight of a material selected from the group consisting of N,N'-diphenyl-N,N'-bis(2-methylphenyl)- [l,l'-bi-phenyl]-4,4'diamine; N,N'-diphenyl-N,N'-bis(3-methylphenyl)-[1,1'-biphenyl]-4,4'-diamine; N,N'-diphenyl-N,N'-bis(4-methylpheny)-[1,1'-biphenyl]-4,4'-diamine; N,N'-diphenyl-N,N'-bis(2-chlorophenyl)-[1,1'-biphenyI]-4,4'-diamine;
N,N'-diphenyl-N,N'-bis(3-chlorophenyl)-[1,1'-biphenyl]-4,4'-diamine and N, N'-diphenyl-N,N'-bis(4-chlorophenyl)-[1,1'-biphenyl]-4,4'-diamine, said photo-conductive layer exhibiting the capability of photogeneration of holes and injection of said holes and said charge transport layer being substantially non-absorbing in the spectral region at which the photoconductive layer generates and injects photogenerated holes but being capable of supporting the injection of photogenerated holes from said photoconductive layer and trans-porting said holes through said charge transport layer.

CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE:

SD 2. An imaging member comprising a charge generation layer comprising a layer of photoconductive material and a contiguous charge transport layer of a polycarbonate resin material having a molecular weight of from about 20,000 to about 120,000 having dispersed therein from about 25 to about 75 percent by weight of one or more compounds having the general formula:

wherein X is selected from the group consisting of an alkyl group, having from 1 to about 4 carbon atoms and chlorine, said photoconductive layer exhibiting the capability of photogeneration of holes and injection of said holes and said charge transport layer being substantially nonabsorbing in the spectral region at which the photoconductive layer generates and injects photogenerated holes but being capable of supporting the injection of photogenerated holes from said photoconductive layer and transporting said holes through said charge transport layer.
SD 3. The member of claim 2 wherein the polycarbonate is poly(4,4'-isopropylidene-diphenylene carbonate).
SD 4. The member according to claim 3 wherein the poly-carbonate has a molecular weight between from about 25,000 to about 45,000.
SD 5. The member according to claim 3 wherein the poly-carbonate has a molecular weight of from about 50,000 to about 120,000.

SD 6. The member of claim 2 wherein the photoconductive material is selected from the group consisting of amorphous selenium, trigonal selenium, and selenium alloys selected from the group consisting of selenium-tellurium, selenium-tellurium-arsenic, selenium-arsenic and mixtures thereof.
SD 7. The member of claim 5 wherein the photoconductive material is selected from the group consisting of amorphous selenium, trigonal selenium, and selenium alloys selected from the group consisting of selenium-tellurium, selenium-tellurium-arsenic, selenium-arsenic and mixtures thereof.