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Publication numberUS3653887 A
Publication typeGrant
Publication dateApr 4, 1972
Filing dateNov 4, 1969
Priority dateNov 4, 1969
Also published asCA929167A, CA929167A1, DE2054061A1
Publication numberUS 3653887 A, US 3653887A, US-A-3653887, US3653887 A, US3653887A
InventorsStewart H Merrill
Original AssigneeEastman Kodak Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Novel {60 ,{60 {40 -bis(aminobenzylidene) aryldiacetonitrile photoconductors
US 3653887 A
Abstract
alpha , alpha '-BIS(AMINOBENZYLIDENE)ARYLIDACETONITRILES ARE USEFUL AS ORGANIC PHOTOCONDUCTORS IN ELECTROPHOTOGRAPHIC ELEMENTS. Elements containing these materials exhibit improved speeds.
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o lJmted Mates Patent [151 3,653,887

Merrilli Apr. 4, 1972 [5 NUVEL 6!,01'-BIS(AMINOBENZYLIDENE) [56] References Cited UNITED STATES PATENTS 3,246,983 4/1966 SUS et al ..96/l .5

72 I t I St I'II'LM '1] R h t ,N.Y. 1 or ewa em es er FOREIGN PATENTS OR APPLICATIONS [73] Assignee: Eastman Kodak Company, Rochester,

NY 39/11546 6/1964 Japan ..96/l.5

[22] Filed: 1969 Primary Examiner-Charles E. Van Horn [2]] Appl. No.: 874,016 Attorney-Eastman Kodak Company, William H. J. Kline,

James R. Frederick and Fred L. Denson [52] U.S.Cl. ..96/1 PC 96/1.5,96/1.6 51 rm. (:1. ..G03g 5/06 [57] ABSTRACT Field ofSearch 11,0:-bis(aminobenzylidene)arylidacetonitriles are useful as organic photoconductors in electrophotographic elements. Elements containing these materials exhibit improved speeds.

6 Claims, No Drawings NOVEL a,a-BIS(AMINOBENZYLIDENE) ARYLDIACETONITRILE PHOTOCONDUCTORS This invention relates to electrophotography, and in particular to photoconductive compositions and elements.

The process of xerography, as disclosed by Carlson in US. Pat. No. 2,297,691, employs an electrophotographic element comprising a support material bearing a coating of a normally insulating material whose electrical resistance varies with the amount of incident electromagnetic radiation it receives during an imagewise exposure. The element, commonly termed a photoconductive element, is first given a uniform surface charge, generally in the dark after a suitable period of dark adaptation. It is then exposed to a pattern of actinic radiation which has the effect of differentially reducing the potential of this surface charge in accordance with the relative energy contained in various parts of the radiation pattern. The differential surface charge or electrostatic latent image remaining on the electrophotographic element is then made visible by contacting the surface with a suitable electroscopic marking material. Such marking material or toner, whether contained in an insulating liquid or on a dry carrier, can be deposited on the exposed surface in accordance with either the charge pattern or discharge pattern as desired. Deposited marking material can then be either permanently fixed to the surface of the sensitive element by known means such as heat, pressure, solvent vapor, or the like, or transferred to a second element to which it can similarly be fixed. Likewise, the electrostatic charge pattern can be transferred to a second element and developed there.

Various photoconductive insulating materials have been employed in the manufacture of electrophotographic elements. For example, vapors of selenium and vapors of selenium alloys deposited on a suitable support and particles of photoconductive zinc oxide held in a resinous, film-forming binder have found wide application in the present-day document copying applications.

Since the introduction of electrophotography, a great many organic compounds have also been screened for their photoconductive properties. As a result, a very large number of organic compounds have been known to possess some degree of photoconductivity. Many organic compounds have revealed a useful level of photoconduction and have been incorporated into photoconductive compositions. Typical of these organic photoconductors are the triphenylamines and the triarylmethane leuco bases. Optically clear photoconductor-containing elements having desirable electrophotographic properties can be especially useful in electrophotography. Such electrophotographic elements can be exposed through a transparent base if desired, thereby providing unusual flexibility in equipment design. Such compositions, when coated as a film or layer on a suitable support, also yield an element which is reusable; that is, it can be used to form subsequent images after residual toner from prior images has been removed by transfer and/or cleaning. Thus far, the selection of various compounds for incorporation into photoconductive compositions to form electrophotographic layers has proceeded on a compound-by-compound basis. Nothing as yet has been discovered from the large number of different photoconductive substances tested which permits effective prediction, and therefore selection of the particular compounds exhibiting the desired electrophotographic properties.

It is, therefore, an object of this invention to provide a novel class of photoconductors having high photosensitivity when electrically charged.

It is another object to provide novel photoconductor-containing compositions which exhibit high electrical speeds.

It is a further object of the invention to provide an improved process utilizing the novel photoconductors described herein.

These and other objects are accomplished by employing a, a-bis(aminobenzylidene )aryldiacetonitriles as photoconductors. These materials can be substituted in various positions by any one or more of several substituents. Typically, the arylene nuclei can be substituted with alkyl, aryl, halogen, alkoxy or aryloxy groups while the amino moiety can have alkyl or aryl substituents. Also, the methyl carbons of the benzylidene moieties can be substituted by aryl or alkyl groups.

Various closely related materials having the grouping wherein Ar is an aryl group and R is hydrogen or an active hydrogen-containing group, have been used as photoconductors in electrophotographic systems. Typical materials are set forth in US. Pat. No. 3,246,983 and US. Ser. No. 706,800 filed Feb. 20, 1968 by Brantly et a1 now US. Pat. No. 3,567,450. According to this invention, it has been found that the photoconductors described herein have enhanced speed over those photoconductors described in the prior art. In particular, substantial increases in speeds are obtained as compared to speeds attainable with many other closely related compounds. These increases in speed are observed when the coating accepts a suitable potential (e.g., 500-600 volts) and the relative speed of the coating is determined on the basis of the reciprocal of the exposure required to reduce the potential of the surface charge by 100 volts (shoulder speed) or to 100 volts (toe speed). The terms shoulder speed and toe speed are terms known in the photographic art with reference to H and D curves. As used herein, such terms refer to corresponding curves resulting from exposure plotted against voltage. The reduction of the surface potential to 100 volts or below is significant in that it represents a requirement for suitable broad area development of an electrostatic image. The relative speed at 100 volts is a measure of the ability to produce and hence to develop or otherwise utilize the electrostatic image. When many conventional photoconductors are used, the surface potential frequently does not drop to or below 100 volts and therefore no speed can be assigned to such a composition. When most photoconductors are used in photoconductive compositions, the surface potentials of such resultant compositions usually drop below 100 volts and thus,

a definite speed can be ascertained. However, these speeds are improved when the photoconductors of this invention are employed.

The preferred a, a'-bis(aminobenzylidene )aryldiaceton itrile photoconductors of the invention are characterized by the following formula:

b. phenoxyethyl, naphthoxymethyl,

f. alkylaminoakyl e.g. methylaminopropyl,

methylaminoethyl, etc., and also including dialkylaminoalkyl e. g. diethylaminoethyl,

dimethylaminopropyl, propylaminooctyl, etc.,

g. arylaminoalkyl, e.g., phenylaminoalkyl, diphenylaminoalkyl, N-phenyl-N-ethylaminopentyl, N-phenyl-N- ethylaminohexyl, naphthylaminomethyl, etc.,

h. nitroalkyl, e.g., nitrobutyl, nitroethyl, nitropentyl, etc.,

i. cyanoalkyl, e.g., cyanopropyl, cyanobutyl, cyanoethyl,

etc.,

j. haloalkyl, e.g., chloromethyl, bromopentyl, chlorooctyl,

etc.,

k. alkyl substituted with an acyl group having the formula wherein R is hydroxy, hydrogen, aryl, e.g., phenyl, naphthyl, etc., lower alkyl having one to eight carbon atoms e.g., methyl, ethyl, propyl, etc., amino including substituted amino, e.g., diloweralkylamino, lower alkoxy having one to eight carbon atoms e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy, naphthoxy, etc.; 4

. 2. an aryl group, e.g., phenyl, naphthyl, anthryl, fluorenyl, etc., including a substituted aryl group such as a. alkoxyaryl, e.g., ethoxyphenyl, methoxyphenyl, propoxynaphthyl, etc.,

b. aryloxyaryl, e.g., phenoxyphenyl, naphthoxyphenyl,

phenoxynaphthyl, etc.

c. aminoaryl, e.g., aminoanthryl, etc.,

d. hydroxyaryl, e.g., hydroxyphenyl, hydroxynaphthyl,

hydroxyanthryl, etc.,

e. biphenylyl,

f. alkylaminoaryl, e.g., methylaminophenyl,

methylaminonaphthyl, etc. and also including dialkylaminoaryl, e.g., diethylaminophenyl, dipropylaminophenyl, etc.,

g. arylaminoaryl, e.g., phenylaminophenyl, diphenylaminophenyl, N-phenyl-N-ethylaminophenyl, naphthylaminophenyl, etc.,

h. nitroaryl e.g., nitrophenyl, nitronaphthyl, nitroanthryl,

aminophenyl, aminonaphthyl,

etc.,

i. cyanoaryl, e.g., cyanophenyl, cyanonaphthyl,

cyanoanthryl, etc.,

j. haloaryl, e.g., chlorophenyl, bromophenyl,

chloronaphthyl, etc., k. aryl substituted with an acyl group having the formula wherein R is hydroxy, hydrogen, aryl, e.g., phenyl, naphthyl, etc., amino including substituted amino, e.g., diloweralkylamino, lower alkoxy having one to eight carbon atoms, e.g., butoxy, methoxy, etc., aryloxy, e.g., phenoxy, naphthoxy, etc., lower alkyl having one to eight carbon atoms, e.g., methyl, ethyl, propyl, butyl, etc.,

1. alkaryl, e.g., tolyl, ethylphenyl, propyl, naphthyl, etc.;

R and R each represent any of the substituents set forth above for R R R and R above and also can be hydrogen;

R R and R each represent any of the substituents set forth above for R, and R and also can be any of the following:

1. an alkoxy group having one to 18 carbon atoms, e.g., methoxy, ethoxy, propoxy, butoxy, etc.;

2. an aryloxy group e.g., phenoxy, naphthoxy, etc.;

3. halogen such as chlorine, bromine, fluorine or iodine.

Typical compounds which belong to the herein described general class of photoconductive materials include the following listed Table I below.

TABLE] I. a,a-Bis( p-diphenylaminobenzylidene )p benzenediacetonitrile II. a,a'-Bis( p-diphenylaminobenzylidene )obenzenediacetonitrile III. a,a Bis(p-diphenylaminobenzylidene )mbenzenediacetonitrile IV. a,a-Bis( p-diethylaminobenzylidene )pbenzenediacetonitrile a,a'-Bis(p-diethylaminobenzylidene)obenzenediacetonitrile VI. a,a'-Bis(p-diethylaminobenzylidene)mbenzenediacetonitrile VII. a,a'-Bis( p-diphenylamino-a-methylbenzylidene )-pbenzenediacetonitrile VIII. a,a-Bis(p-diphenylamino-a-phenylbenzylidene)-pbenzenediacetonitrile IX. 01,01-Bis(4-diphenylamino-B-methylbenzylidene )-pbenzenediacetonitrile X. a,a'-Bis(4-diphenylamino-3-phenylbenzylidene)-pbenzenediacetonitrile XI. a,a'-Bis(4-diphenylamino-3-methoxybenzylidene)-pbenzenediacetonitrile XII. a,a-Bis(4-diphenylamino-B-phenoxybenzylidene)-pbenzenediacetonitrile XIII. a,a-Bis(4diphenylamino-3-chlorobenzylidene)-pbenzenediacetonitrile I XIV. oz,a-Bis(4-diphenylaminobenzylidene )-ptoluenediacetonitrile XV. a,a-Bis(4-diphenylaminobenzylidene )-panisolediacetonitrile XVI. 01,01-Bis(4-diphenylaminobenzylidene)-p-(phenoxybenzene)diacetonitrile XVII. a,a'-Bis(4-diphenylaminobenzylidene)-p-(phenylbenzene)diacetonitrile XVIII. a,a'-Bis(4-diphenylaminobenzylidene )-p- (chlorobenzene)diacetonitrile Electrophotographic elements of the invention can be prepared with the photoconducting compounds of the invention in the usual manner, i.e., by blending a dispersion or solution of a photoconductive compound together with a binder, when necessary or desirable, and coating or forming a selfsupporting layer with the photoconductor-containing materials. Mixtures of the photoconductors described herein can be employed. Likewise, other photoconductors known in the art such as those described in Light, Belgian Pat. No. 705,117 dated Apr. 16, 1968 can be combined with the present photoconductors. In addition, supplemental materials useful for changing the spectral sensitivity or electrophotosensitivity of the element can be added to the composition of the element when it is desirable to produce the characteristic effect of such materials.

The photoconductive layers of the invention can also be sensitized by the addition of effective amounts of sensitizing compounds to exhibit improved electrophotosensitivity. Sensitizing compounds useful with the photoconductive compounds of the present invention can be selected from a wide variety of materials, including such materials as pyrylium dye salts including thiapyrylium dye salts and selenapyrylium dye salts disclosed in VanAllan et'al. U.S. Pat. No. 3,250,615; fluorenes, such as 7,12-dioxo-l 3-dibenzo (a,h)fluorene, 5,10- dioxo-4a,1 l-diazobenzo(b)-fluorene, 3,13-dioxo-7-oxadibenzo (b,g)fluroene, and the like; aggregate-type sensitizers of the type described in Light, Belgian Pat. No. 705,117, dated Apr. 16, 1968; aromatic nitro compounds of the kinds described in U.S. Pat. No. 2,610,120; anthrones like those disclosed in U.S. Pat. No. 2,670,284; quinones, U.S. Pat. No. 2,670,286; benzophenones U.S. Pat. No. 2,670,287; thiazoles U.S. Pat. No. 2,732,301; mineral acids; carboxylic acids, such as maleic acid, dichloroacetic acid, trichloroacetic acid and salicyclic acid; sulfonic and phosphoric acids; and various dyes, such as cyanine (including carbocyanine), merocyanine, diarylmethane, thiazine, azine, oxazine, xanthene, phthalein, acridine, azo, anthraquinone dyes and the like and mixtures thereof. The sensitizers preferred for use with the compounds of this invention are selected from pyrylium salts including selenapyrylium salts and thiapyrylium salts, and cyanine dyes including carbocyanine dyes.

Where a sensitizing compound is employed with the binder and organic photoconductor to form a sensitized electrophotographic element, it is the normal practice to mix a suitable amount of the sensitizing compound with the coating composition so that, after thorough mixing, the sensitizing compound is uniformly distributed in the coated layer.

Other methods of incorporating the sensitizer or the effect of the sensitizer may, however, be employed consistent with the practice of this invention. In preparing the photoconductive layers, no sensitizing compound is required to give photoconductivity in the layers which contain the photoconducting substances, therefore, no sensitizer is required in a particular photoconductive layer. However, since relatively minor amounts of sensitizing compound give substantial improvement in speed in such layers, the sensitizer is preferred. The amount of sensitizer than can be added to a photoconductor-incorporating layer to give effective increases in speed can vary widely. The optimum concentration in any given case will vary with the specific photoconductor and sensitizing compound used. In general, substantial speed gains can be obtained where an appropriate sensitizer is added in a concentration range from about 0.0,001 to about 30 percent by weight based on the weight of the film-forming coating composition. Normally, a sensitizer is added to the coating composition in an amount by weight from about 0.005 to about 5.0 percent by weight of the total coating composition.

Preferred binders for use in preparing the present photoconductive layers are film-forming, hydrophobic polymeric binders having fairly high dielectric strength which are good electrically insulating film-forming vehicles.

Typical ofthese materials are:

I. Natural resins including gelatin, cellulose ester derivatives such as alkyl esters of carboxylated cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, carboxy methyl hydroxy ethyl cellulose, etc.;

II. Vinyl resins including a. polyvinyl esters such as a vinyl acetate resin, a copolymer of vinyl acetate and crotonic acid, a copolymer of vinyl acetate with an ester of vinyl alcohol and a higher aliphatic carboxylic acid such as lauric acid or stearic acid, polyvinyl stearate, a copolymer of vinyl acetate and maleic acid, a poly(vinylhaloarylate) such as poly(vinylm-bromobenzoate-covinyl acetate), 2 terpolymer of vinyl butyral with vinyl alcohol and vinyl acetate, etc.;

b. vinyl chloride and vinylidene chloride polymers such as a poly(vinylchloride), a copolymer of vinyl chloride and vinyl isobutyl ether, a copolymer of vinylidene chloride and acrylonitrile, a terpolymer of vinyl chloride, vinyl acetate and vinyl alcohol, poly(vinylidene chloride) a terpolymer of vinyl chloride, vinyl acetate and maleic anhydride, a copolymer of vinyl chloride and vinyl acetate, etc.;

styrene polymers such as polystyrene, a nitrated polystyrene, a copolymer of styrene and monoisobutyl maleate, a copolymer of styrene with methacrylic acid, a

copolymer of styrene and butadiene, a copolymer of dimethylitaconate and styrene, polymethylstyrene, etc.;

d. methacrylic acid ester polymers such as a poly(alkylmethacrylate), etc.;

e. polyolefins such as chlorinated polyethylene, chlorinated polypropylene, poly(isobutylene), etc.;

f. poly(vinyl acetals) such as poly(vinyl butyral), etc.; and

g. poly(vinyl alcohol);

III. Polycondensates including a. a polyester of 1,3-disulfobenzene and 2,2-bis(4-hydroxyphenyl)propane;

b. a polyester of diphenyl-p,p-disulphonic acid and 2,2-

bis(4-hydroxyphenyl)propane;

c. a polyester of 4,4'-dicarboxyphenyl ether and 2,2-bis(4- hydroxyphenyl)propane;

d. a polyester of 2,2-bis(4-hydroxyphenyl)propane and fumaric acid;

e. polyester of pentaerythritol and phthalic acid;

f. resinous terpene polybasic acid;

g. a polyester of phosphoric acid and hydroquinone;

h. polyphosphites;

i. polyester ofneopentylglycol and isophthalic acid;

j. polycarbonates including polythiocarbonates such as the polycarbonate of 2,2-bis( 4-hydroxyphenyl)propane;

k. polyester of isophthalic acid, 2,2-bis[4-(,B-hydroxyethoxy)phenyl]propane and ethylene glycol;

l. polyester of terephthalic acid, 2,2-bis[4-(fi-hydroxyethoxy)phenyl]propane and ethylene glycol;

m. polyester of ethylene glycol, neopentyl,

terephthalic acid and isophthalic acid;

n. polyamides;

o. ketone resins; and

p. phenol-formaldehyde resins:

IV. Silicone resins;

V. Alkyd resins including styrene-alkyd resins, siliconealkyd resins, soya-alkyd resins, etc.;

VI. Polyamides.

VII. Paraffin; and

VIII. Mineral waxes.

Solvents useful for preparing coating compositions with the photoconductor of the present invention can include a wide variety of organic solvents for the components of the coating composition.

Typical solvents include:

I. aromatic hydrocarbons such as benzene, naphthalene, etc., including substituted aromatic hydrocarbons such as toluene, xylene, mesitylene, etc;

2. ketones such as acetone, 2-butanone, etc.;

3. halogenated aliphatic hydrocarbons such as methylene chloride, chloroform, ethylene chloride, etc.;

4. ethers including cyclic ethers such as tetrahydrofuran, ethylether;

5. mixtures of the above.

In preparing the coating compositions utilizing the photoconducting compounds disclosed herein useful results are obtained where the photoconductive substance is present in an amount equal to at least about 1 weight percent of the coating composition. The upper limit in the amount of photoconductive material present can be widely varied in accordance with usual practice. It is normally required that the photoconductive material be present in an amount ranging from about 1 weight percent of the coating composition to about 99 weight percent of the coating composition. A preferred weight range for the photoconductive material in the coating composition is from about 10 weight percent to about 60 weight percent.

Coating thicknesses of the photoconductive composition on a support can vary widely. Normally, a wet coating thickness in the range of about 0.001 inch to about 0.01 inch is useful in the practice of the invention. A preferred range of coating thickness is from about 0.002 inch to about 0.006 inch before drying although such thicknesses can vary widely depending on the particular application desired for the electrophotographic element.

Suitable supporting materials for the photoconductive layers of the present invention can include any of the electrically conducting supports, for example, various conducting papers; aluminum-paper laminates; metal foils, such as aluminum foil, zinc foil, etc.; metal plates such as aluminum, copper, zinc, brass, and galvanized plates; vapor deposited metal layers such as silver, nickel or aluminum on conventional film supports such as cellulose acetate, poly(ethylene terephthalate), polystyrene and the like conducting supports.

An especially useful conducting support can be prepared by coating a transparent film support material such as poly(ethylene terephthalate) with a layer containing a semiconductor dispersed in a resin. A suitable conducting coating can be prepared from the sodium salt of a carboxyester lactone of a maleic anhydride-vinyl acetate copolymer, cuprous iodide and the like, Such conducting layers and methods for their optimum preparation and use are disclosed in US. Pat. Nos. 3,007,901, 3,245,833 and 3,267,807.

The compositions of the present invention can be employed in photoconductive elements useful in any of the well known electrophotographic processes which require photoconducglycol,

tive layers. One such process is the xerographic process. in a process of this type, an electrophotographic element held in the dark, is given a blanket positive or negative electrostatic charge as desired by placing it under a corona discharge to give a uniform charge to the surface of the photoconductive layer. This charge is retained by the layer owing to the substantial dark insulating property of the layer, i.e., the low conductivity of the layer in the dark. The electrostatic charge formed on the surface of the photoconductive layer is then selectively dissipated from the surface of the layer by imagewise exposure to light by means of a conventional exposure operation such as for example, by a contact-printing technique, or by lens projection of an image, or reflex or bireflex techniques and the like, to thereby form a latent electrostatic image in the photoconductive layer. Exposing the surface in this manner forms a pattern of electrostatic charge by virtue of the fact that light energy striking the photoconductor causes the electrostatic charge in the light struck areas to be conducted away from the surface in proportion to the illuminance on a particular area.

The charge pattern produced by exposure is then developed or transferred to another surface and developed there, i.e., either the charged or uncharged areas rendered visible, by treatment with a medium comprising electrostatically responsive particles having optical density. The developing electrostatically responsive particles can be in the form of a dust, or powder and generally comprise a pigment in a resinous carrier called a toner. A preferred method of applying such a toner to an electrostatic image for solid area development is by the use of a magnetic brush. Methods of forming and using a magnetic brush toner applicator are described in the following U.S. Pat. Nos. 2,786,439; 2,786,440; 2,786,441; 2,81 1,465; 2,874,063; 2,984,163; 3,040,704; 3,117,884 and reissue Re 25,779. Liquid development of the latent electrostatic image may also be used. In liquid development the developing particles are carried to the image-bearing surface in an electrically insulating liquid carrier. Methods of development of this type are widely known and have been described in the patent literature, for example, U.S. Pat. No. 2,297,691 and in Australian Pat. No. 212,315. In dry developing processes the most widely used method of obtaining a permanent record is achieved by selecting a developing particle which has as one of its components a low-melting resin. Heating the powder image then causes the resin to melt or fuse into or on the element. The powder is, therefore, caused to adhere permanently to the surface of the photoconductive layer. In other cases, a transfer of the charge image or powder image formed on the photoconductive layer can be made to a second support such as paper which would then become the final print after developing and fusing or fusing respectively. Techniques of the type indicated are well known in the art and have been described in a number of U.S. and foreign patents, such as U.S. Pats. Nos. 2,297,691 and 2,551,582, and in RCA Review," vol. (1954) pages 469-484.

The compositions of the present invention can be used in electrophotographic elements having many structural variations. For example, the photoconductive composition can be coated in the form of single layers or multiple layers on a suitable opaque or transparent conducting support. Likewise, the layers can be contiguous or spaced having layers of insulating material or other photoconductive material between layers or overcoated or interposed between the photoconductive layer or sensitizing layer and the conducting layer. It is also possible to adjust the position of the support and the conducting layer by placing a photoconductor layer over a support and coating the exposed face of the support or the exposed or overcoated face of the photoconductor with a conducting layer. Configurations differing from those contained in the examples can be useful or even preferred for same or different application for the electrophotographic element.

The following examples are included for a further understanding of this invention.

EXAMPLE 1 Several coating dopes containing the following materials are prepared:

Organic photoconductor 0.5 g. Polymeric binder 1.5 g. Sensitizer 0.02 g. Methylene chloride 1 1.7 ml.

The resulting compositions are coated at a wet thickness of 0.004 inch on a conducting layer comprising the sodium salt of a carboxyester lactone, such as described in U.S. Pat. No. 3,120,028, which in turn is coated on a cellulose acetate film base. The coating blocks are maintained at a temperature of F. These electrophotographic elements are charged under a positive corona source until the surface potentials, as measured by an electrometer probe, reach between about 600 volts. They are then subjected to exposure from behind a stepped density gray scale to a 3,000 K. tungsten source. The exposure causes reduction of the surface potential of the portion of the element under each step of the gray scale from its initial potential, V0, to some lower potential, V, whose exact value depends on the actual amount of exposure in meter-candle-second received by the area. The results of the measurements are plotted on a graph of surface potential V vs. log exposure for each step. The speed is the numerical expression of 10 multiplied by the reciprocal of the exposure in meter-candle-seconds required to reduce the 500 to 600 volt charged surface potential to volts above 0 volt. The reduction of the surface potential to 100 volts or below is significant in that it represents a requirement for suitable broad area development ofa latent image. This speed at 100 volts is a measure of the ability to produce and henceforth to develop or otherwise utilize the charge image, higher speeds requiring less illumination to produce a usable charge image. When the photoconductor is absent from the coating, the surface potential does not drop to, or below, 100 volts and no speed value can be assigned. This is also the case when a compound is present in the composition but is ineffective as a photoconductor. The speeds of the various photoconductive compositions are shown in Table 11 below. The sensitizers used are referred to below as follows:

B. 2,6-bis(4-ethylphenyl)-4-(4-amyloxyphenyl)thiapyryliurn perchlorate E. Rhodamine B F. 2,4-bis(4-ethoxyphenyl)-6-(4-n-amyloxystyryl)pyrylium fluoroborate H. 2,6-bis(4-ethoxyphenyl)-4-(4-n-amyloxyphenyl)thiapyrylium perchlorate The binders used are referred to below as follows:

Vitel a polyester resin sold by Goodyear Tire and Rubber Co. comprising poly(4,4-isopropylidenebisphenyleneoxyethylene-co-ethyleneterephthalate) Pvm BB poly(vinyl-m-bromobenzoate-co-vinylacetate) The photoconductor used is Compound I of Table I.

TABLE ll Sensitizer Binder Speed Vitel Vitel Pvm BB Pvm BB Vitel EXAMPLE 2 related material. The speed data in the following Table III demonstrates that the photoconductors of this invention are substantially faster than the photoconductor used in this Ex ample.

TABLE III Sunni/e1 Binder Speed Vitcl Vite] Pvm BB Pvm BB Vite] EXAMPLE 3 A composition in the form of a dope consisting of the following materials is coated at a wet thickness of0.004 inch on a poly(ethylene terephthalate) film support bearing a conducting layer of sodium salt of a carboxyester resin lactone:

Photoconduclor 025 g. Polymeric binder Vitel LOO g. Sensitizer 0.0] g. Dichloromelhane 9.60 g.

The coating block is maintained at a temperature of 90 F. until the solvent is removed. In a darkened room, the surface of the photoconductive layer so prepared is charged to a potential of about +600 volts under a corona charger. The layer is then covered with a transparent sheet bearing a pattern of opaque and light-transmitting areas and exposed to the radiation from an incandescent lamp with an illumination intensity of about 75 meter-candles for 12 seconds. The resulting electrostatic latent image is developed by cascading over the surface of the layer negatively charged black thermoplastic toner particles on glass bead carriers. The quality of the images reproduced using the various photoconductors described herein are set forth in the following Table V.

TABLE V Photoconductor Image Quality none non reproduced I Good II Good III Good IV Good V V Good The invention has been described in detail with particular reference to preferred embodiments thereof, but, it will be understood that variations and modifications can be efiected within the spirit and scope of the invention.

I claim:

1. In an electrophotographic process for reproducing continuous tone images wherein an electrostatic charge pattern is formed on an electrophotographic element, the improvement characterized in that said electrophotographic element has a photoconductive layer comprising a photoconductor having the formula:

wherein R R R and R are each selected from the group consisting of an aryl group and an alkyl group,

R and R are each selected from the group consisting of an alkyl group, an aryl group and a hydrogen atom and R R and R are each selected from the group consisting of an alkyl group, an aryl group, an alkoxy group, an aryloxy group, a halogen atom and a hydrogen atom.

2. The process of claim 1 wherein R R R and R are aryl groups.

3. The process of claim 1 wherein R R and R are hydrogen atoms.

4. The process of claim 1 wherein R and R are hydrogen atoms.

5. The process of claim I wherein said photoconductive composition contains a sensitizer for said photoconductor.

6. In an electrophotographic process for reproducing continuous tone images wherein an electrostatic charge pattern is formed on an electrophotographic element, the improvement characterized in that said electrophotographic element has a layer of a photoconductive composition comprising:

a. from about 10 to about 60 percent by weight based on said photoconductive composition of a, a'-bis( p-diphenylaminobenzylidene)-p-bezenediacetonitrile as the organic photoconductor,

b. a film-forming polymeric binder for said photoconductor and c. from about 0.005 percent to about 5 percent by weight based on said photoconductive composition of a sensitizer for said photoconductive composition.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US3246983 *Apr 6, 1960Apr 19, 1966Azoplate CorpElectrophotographic reproduction process
JP39011546A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3873311 *Feb 19, 1974Mar 25, 1975Eastman Kodak CoAggregate photoconductive compositions and elements containing a styryl amino group containing photoconductor
US3873312 *Feb 19, 1974Mar 25, 1975Eastman Kodak CoPhotoconductive composition and elements containing a styryl amino group containing photoconductor
US4111693 *Dec 22, 1976Sep 5, 1978Eastman Kodak CompanyMultilayer aggregate photoconductive elements
US4175961 *Apr 3, 1978Nov 27, 1979Eastman Kodak CompanyMulti-active photoconductive elements
US6555959 *Sep 29, 2000Apr 29, 2003Fuji Photo Film Co., Ltd.Material for light emitting device, light emitting device using thereof, and amine compound
Classifications
U.S. Classification430/74, 430/73
International ClassificationC09B23/14, G03G5/06, C07C255/58, G03C5/06
Cooperative ClassificationC07C255/00, G03G5/0672, G03G5/0612, G03G5/0618, C09B23/143
European ClassificationC07C255/00, G03G5/06B7, G03G5/06B5, G03G5/06H2D, C09B23/14D