US3615406A

US3615406A - Photoconductive elements containing polymeric binders

Info

Publication number: US3615406A
Application number: US772362A
Authority: US
Inventors: Stewart H Merrill
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1968-10-31
Filing date: 1968-10-31
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26

Abstract

Photoconductive elements containing a photoconductor and a binder for the photoconductor comprising a poly(alkylidenebisaryloxyalkyl-co-alkylene terephthalate) are described. The described elements can be sensitized and charged either negatively or positively and used to prepare images electrophotographically.

Description

Miited States Patent Inventor Stewart H. Merrill Rochester, N.Y.

Appl. No. 772,362

Filed Oct. 31, 1968 Patented Oct. 26, 1971 Assignee Eastman Kodak Company Rochester, NY.

PHOTUCONDUCTIWE ELEMENTS CONTAINHNG POLYMERIC BKNDIERS 17 Claims, No Drawings 11.8. C1 96/15, 260/47 C 1m. (31 603g 5/00, C08g19/O0, HOlc 13/00 Field of Search 260/47 C;

[56] References Cited UNITED STATES PATENTS 3,245,786 4/1966 Cassiers et al. 96/1 3,408,182 10/1968 Mammino 96/15 OTHER REFERENCES 794,773 Defense Publication 260/47 (C) 863 O.G. 1001 Primary Examiner-George F. Lesmes Assistant ExaminerM. B. Wittenberg Attorneys-William H. J. Kline, James R. Frederick and Fred L. Denson PHOTOCONDUCTIVE ELEMENTS CONTAINING POLYMERIC lBllNDERS This invention relates to novel electrophotographic elements having coatings of binder-containing photoconductive compositions.

Binder-containing photoconductive compositions have been widely used in the preparation of electrophotographic elements. in electrophotographic reproduction processes, these elements are utilized in the formation of latent electrostatic images. In some applications the photoconductive compositions contain an organic photoconductor and a sensitizer uniformly admixed in an inert resinous binder. Many binders are currently used in connection with a wide variety of available organic photoconductor compounds and compositions. Typical binders are ordinary polymeric materials, e.g., phenolic resins, ketone resins, acrylic ester resins, polystyrene, etc. However, these binders usually do not impart any particular improvement in light sensitivity to the system. The light sensitivity as indicated by the electrical speed of these particular systems is ordinarily due wholly to the organic photoconductor and sensitizer. Other binders have been found to contribute significantly to the light sensitivity of the system. However, the selection of these polymers for incorporation into photoconductive compositions to form electrophotographic layers has proceeded on a compound-by-compound basis. Nothing has yet been discovered from the numerous binders tested which permits effective prediction and selection of particular polymers exhibiting the desired properties.

it is, therefore, an object of this invention to provide improved novel binder-containing photoconductive compositions which exhibit high light sensitivities.

It is another object to provide transparent electrophotographic elements having the high speed characteristic of the novel photoconductive compositions of this invention.

These and other objects of this invention are accomplished by a photoconductive composition which contains a photoconductor by a photoconductive composition which contains a photoconductor admixed with a binder therefor which is a poly(alkylidenebisaryloxyalkyl-co-alkylene terephthalate) wherein the alkylene moiety contains three to l carbon atoms. It has been discovered that such compositions exhibit increased light sensitivities as evidenced by greater speeds. In particular, substantial increases in speeds are obtained as compared to speeds attainable with many other polymeric binder compositions. 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 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. The relative speed at 100 volts in a measure of the ability to produce and henceforth to develop or otherwise utilize the latent image. When the photoconductor is absent from the coating and only a conventional binder is used, the surface potential does not drop to or below 100 volts and therefore no speed can be assigned to such a composition. When a photoconductor is part of the coating in many conventional polymeric binders, the surface potentials of such resultant compositions usually drop below 100 volts, and thus, a definitespeed can be ascertained. How ever, these speeds are improved when the binders of this invention are employed.

The poly(alkylidenebisaryloxyalkyl-co-alkylene terephthalate) copolyesters of this invention include those consisting essentially ofthe following repeating units:

wherein Z is an alkylene group having three to 10 carbon atoms including substituted as well as unsubstituted alkylene radicals such as a. a straight chain or branched alkylene hydrocarbon radical, e.g., those represented by the formula R1 -c 6 m l l i I R2 where R,, R R and R are either hydrogen or an alkyl radical having one to five carbon atoms, s is an integer from zero to seven when R or R is an alkyl radical and one to seven when R and R are hydrogen and I is an integer from one to seven, including a trimethylene radical, a tetramethylene radical, a propylene radical, a pentamethylene radical a neopentylene radical, a hexamethylene radical, etc;

b. an oxydialkylene radical or a thiadialkylene radical, e.g., those represented by the formula where D is an oxygen or sulfur atom and n and 0 are integers from two to seven including an oxydiethylene radical, a thiadiethylene radical, etc.;

c. an alkylene bis(oxyalkylene) radical or an alkylene bis(thiaalkylene) radical, e.g., those represented by the forwhere D is an oxygen or sulfur atom and p, q and r are integers from two to six, including a methylene bis(oxyethylene) radical, an ethylene bis(thiaethylene) radical, an ethylene bis(oxyethylene radical), etc.

d. a cycloalkylene hydrocarbon radical including substituted cycloalkylene hydrocarbon radicals, e.g., those represented by the formula where Q is the atoms necessary to complete a 3 to 6 carbon cycloalkylene radical and u and v are integers from zero to five, including a cyclohexylenediemthylene radical, a cyclopentylenedimethylene radical, a cyclobutylenediemthylene radical, a cyclobutylenediethylene radical, a cyclobutylene radical, 2,2,4,4-tetramethyl-l,3-cyclobutylene radical, etc;

e. D and E each can be a hydrogen atom, a halogen atom, an

alkyl group, an aryl group, an alkoxy group or an aryloxy group. The copolyester binders of this invention suitably contain 2 to percent and preferably 30 to 60 percent of repeating unit A. The binder also suitably contains from about 20 to 98 percent and preferably 40 to 70 percent of repeating unit B. The polymer contains these units arranged in a random, linear fashion. Binders comprising such polymers improve the electrical speed of the photoconductive composition.

Exemplary of a few of the many polymers useful as binders in this invention are:

l. Poly(4,4'-isopropylidenebisphenoxyethyl-co-trimethylene 3. Poly(4,4-isopropylidenebisphenoxyethyl-co-pentamethylene terephthalate) 4. Poly(4,4'-isopropylidenebisphenoxyethyl-co-oxydiethylene terephthalate) 5. Poly(4,4-isopropylidenebisphenoxyethyl-co-neopentyl terephthalate) phthalate) 6. Poly(4,4-isopropylidenebisphenoxyethyl-co-cyclohexylenedimethylene terephthalate) 7. Poly(4,4-isopropylidenebisphenoxyethyl-co-cyclobutylenedimethylene terephthalate) 8. Poly(4,4'-isopropylidenebisphenoxyethyl-co-thiadiethylene terephthalate) 9. Poly[4,4-isopropylidenebisphenoxyethyl-co-ethylenebis(oxyethylene) terephthalate] l0. Poly[4,4-isopropylidenebisphenoxyethyl-co-ethylenebis(thiaethylene) terephthalate] l l. Poly(4,4'-isopropylidenebisphenoxyethyl-co-2,2,4,4- tetramethyl-l ,3-cyclobutylene terephthalate) 12. Poly( 4,4-isopropylidenebisphenoxyethyl-cotetramethylene-4-bromoterephthalate) 13. Poly(4,4'-isopropylidenebisphenoxyethyl-cotetramethylene-S-phenoxyterephthalate) 14. Poly( 4,4-isopropylidenebisphenoxyethyl-co-propylene terephthalate) l5 Poly( 4,4-isoprpylidenebisphenoxyethyl-cotetramethylene-2,S-dichloroterephthalate) 16. Poly( 4,4-isopropylidenebisphenoxyethyl-cotetramethylene--methoxyterephthalate) 17. Poly( 4,4'-isopropylidenebisphenoxyethyl-cotetramethylene-S-phenylterephthalate) In preparing typical electrophotographic elements utilizing the polymeric binders of this invention, an organic photoconductor is dissolved in a solution of binder and solvent and then, after thorough mixing, the composition is coated on an electrically conducting support in a well-known manner, such as swirling, spraying, doctor blade coating, and the like.

The novel binders of this invention improve the electrical speeds of compositions containing a wide variety of photoconductors including inorganic photoconductors such as zinc oxide, titanium dioxide, cadmium sulfide and the like and organic photoconductors including organometallic photoconductors.

Typical photoconductors useful with the binders of this inventions are described below.

B. Photoconductors represented by the formula wherein A represents a nononuclear or polynuclear divalent aromatic radical, either fused or linear (cg, phenyl, naphthyl, biphenyl, binaphthyl, etc.), or a substituted divalent aromatic radical of these types wherein said substitutent can comprise a member such as an acyl group having from one to about six carbon atoms (e.g., acetyl, propionyl, butryl, etc.), an alkyl group having from one to about six carbon atoms (e.g., methyl, ethyl, propyl, butyl, etc.), an alkoxy group having from one to about six carbon atoms (e.g., methoxy, ethoxy, propoxy, pentoxy, etc), or a nitro group; A represents a mononuclear or polynuclear monovalent aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, etc), or a substituted monovalent aromatic radical wherein said substituent can comprise a member, such as an acyl group having from one to about six carbon atoms (e.g., acetyl,

propionyl, butyryl, etc), an alkyl group having from one to about six carbon atoms (e.g., methyl, ethyl, propyl, butyl, etc.), an alkoxy group having from one to about six carbon atoms (e.g., methoxy, propoxy, pentoxy, etc.), or a nitro group; O can represent a hydrogen atom or an aromatic amino group, such as A'NH-; b represents an integer from one to about twelve, and L represents a hydrogen atom, a mononuclear or polynuclear aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, etc.), a substituted aromatic radical wherein said substituent comprises an alkyl group, alkoxy group, an acyl group, or a nitrate group or a poly(4'-vinylphenyl) group which is bonded to the nitrogen atom by a carbon atom of the phenyl group, these materials being more fully described in U.S. Pat. No. 3,265,496.

C. Polyarylalkane photoconductors including leuco bases of diaryl or triarylmethane dye salts, l,l l-triarylakanes wherein the alkane moiety has at least two carbon atoms and tetraaryl methanes having an amino group substituted in at least one of the aryl nuclei attached to the alkane and methane moeties of the latter two classes of photoconductors which are nonleuco base materials; and also other polyarylalkanes included by the formula HLE wherein each of D, E and G is an aryl group and J is a hydrogen atom, an alkyl group, or an aryl group, at least one of D, E and G containing an amino substituent, the aryl groups attached to the central carbon atom being preferably phenyl groups, although naphthyl groups can also be used including substituted aryl groups containing substituents such as alkyl and alkoxy typically having one to eight carbon atoms, hydroxy, halogen, etc. in the ortho, meta or para positions, ortho-substituted phenyl being preferred; the aryl groups can also be joined together or cyclized to form a fluorene moiety, for example; the amino substituent can be represented by the formula wherein each R can be an alkyl group typically having one to eight carbon atoms, a hydrogen atom, an aryl group, or together the necessary atoms to form a heterocyclic amino group typically having five to six atoms in the ring such as morpholino, pyridyl, pyrryl, etc.', at least one of D, E and G preferably being a p-dialkylaminophenyl groups, when J is an alkyl group, such an alkyl group more generally has one to seven carbon atoms, these materials being more fully described in U.S. pat. No. 3,274,000, French Pat. No. l,383,46l and in U.S. Ser. No. 627,857 filed Apr. 3, 1967 by Seus and Goldman, now U.S. Pat. No. 3,542,544.

D. Photoconductors comprising 4-diarylamino-substituted chalcones having the formula wherein R and R, are each aryl radicals, aliphatic residues of one to 12 carbon atoms such as alkyl radicals preferably having one to four carbon atoms, or hydrogen; particularly advantageous results being obtained when R is a phenyl radical including a substituted phenyl radical and where R is diphenylaminophenyl, di-methylaminophenyl or phenyl, these materials being more fully described in Fox application, U.S. Ser, No. 613,846, now U.S. Pat. No. 3,526,50l.

E. Nonionic cycloheptenyl compounds which may be substituted with substituents such as (a) an aryl radical including substituted as well as unsubstituted aryl radicals, (b) a hydroxy radical, (c) an azido radical, (d) a heterocyclic radical having five to six atoms in the heterocyclic nucleus and at least one heteronitrogen atom, and including substituted and unsubstituted heterocyclic radicals, and (e) an oxygen-linked cycloheptenyl moiety. The substitution on the cycloheptenyl nucleus occurs at an unsaturated carbon atom when the cycloheptenyl moiety is a conjugated triene with no aromatic structure fused thereto. However, if there is at least one arematic structure fused to the cycloheptenyl moiety, then the substituents are attached to a saturated carbon atom. Additional photoconductors within this class are included in one of the following formulas where E and G can be either:

a. a phenyl radical,

b. a naphthyl radical,

c. a heterocyclic radical having five to six atoms in the heterocyclic nucleus and at least one heteronitrogen atom,

d. a hydroxyl radical, or

e. an oxygen-containing radical having a structure such that the resultant cycloheptenyl compound is a symmetrical ether; nucleus and dnucleus; 11967, D can be any of the substituents defined for E and G above and is attached to a carbon atom in the cycloheptenyl nucleus having a double bond; (R and R,,,), (R and R (R,, and R and (R, and R are together the necessary atoms to complete a benzene ring fused to the cycloheptenyl nucleus; these compounds being more fully described in U.S. Ser. No. 654,091 filed July 18, 1967, now U.S. Pat. No. 3,533,786.

F. Compounds containing an as a haloalkyl or an alkoxyalkyl radical,

b. a phenyl radical including a substituted phenyl radical such as a naphthyl, an aminophenyl or a hydroxyphenyl radical,

c. a halogen atom,

d. an amino radical including substituted as well as unsubstituted amino radicals such as an alkylamino or a phenyl-alkylamino radical;

e. an alkoxy radical,

f. a hydroxyl radical,

g. a cyano radical,

h. a heterocyclic radical such as a pyrazyl, a carbazolyl or a pyridyl radical; or (2) tetra-substituted hydrazines containing substituents which are substituted or unsubstituted phenyl radicals, or heterocyclic radicals having five to six atoms in the heteronucleus, suitable results being obtained when all four substituents are not unsubstituted phenyl radicals, i.e., if at least on substituent is a substituted phenyl radical or a heterocyclic radical having five to six atoms in the heteronucleus. Other tetra-substituted hydrazines include those having the following formula:

wherein D,, E G, and J are each either a. a substituted phenyl radical such as a naphthyl radical, an alltylphenyl radical, a halophenyl radical, a hydroxyphenyl radical, a haloalkylphenyl radical or a hydroxyalkylphenyl radical or b. a heterocyclic radical such as an imidazolyl radical, a furyl radical or a pyrazoline radical.

In addition, J l and E 1 can also be c. an unsubstituted phenyl radical, Especially preferred are those tetra-substituted hydrazines wherein both D, and G are either substituted phenyl radicals or heterocyclic radicals. These compounds are more fully described in U.S. Ser. No. 673,962 filed Oct. 9, 1967, now U.S. Pat. No. 3,542,546.

G. Organic compounds having a 3,3'-bis-aryl-2-pyrazoline nucleus which is substituted in either five-member ring with the same or different substituents. The one and five positions on both pyrazoline rings can be substituted by an aryl moiety including unsubstituted as well as substituted aryl substituents such as alkoxyaryl, allcaryl, alkaminoaryl, carboxyaryl, hydroxyaryl and haloaryl. The four position can contain hydrogen or unsubstituted as well as substituted alltyl and aryl radicals such as alltoxyaryl, alkaryl, alkaminoaryl, haloaryl, hydroxyaryl, alkoxyallcyl, aminoalkyl, carboxyaryl, hydroxyalkyl and haloalkyl. Other photoconductors in this class are represented by the following structure:

D D';,, 1;, and J' can be either a phenyl radical including a substituted phenyl radical such as a tolyl radical or a naphthyl radical including a substituted naphthyl radical,

E E' G G' L and L';, can be any of the substituents set forth above and in addition can be either a hydrogen atom or an alkyl radical containing one to eight carbon atoms. These organic photoconductors are more fully described in U.S. Ser. No. 664,642 filed Aug. 31, 1967., now U.S. Pat. No. 3,527,602.

1H. Triarylamines in which at least one of the aryl radicals is substituted by either a vinyl radical or a vinylene radical having at least one active hydrogen-containing group. The phrase vinylene radical" includes substituted as well as unsubstituted vinylene radicals and also includes those radicals having at least one and as many as three repeating units of vinylene groups such as (Ch =CH) wherein n is an integer of from one to three. Groups which contain active hydrogen are well known in the art, the definition of this term being set forth in several textbooks such as Advanced Organic Chemistry," R. C. Fuson, pp. 154-157, John Wiley & Sons, 1950. The term active hydrogen'containing group" as used herein includes those compounds encompassed by the discussion in the textbook cited above and in addition includes those compounds which contain groups which are hydrolyzable to active hydrogen-containing groups. Typical active hydrogen-containing groups substituted on the vinyllene radical of the triarylamine include:

a. carboxy radicals,

b. hydroxy radicals,

c. ethynyl radicals,

d. ester radicals (e.g.,

wherein R is alkyl or aryl) including cyclic ester radicals wherein R is a cyclic alkylene radical connected to a vinylene combination such as is found in coumarin derivatives),

e. carboxylic acid anhydride radicals,

f. semicarbazano radicals,

g. cyano radicals,

h. acyl halide radicals (e.g.,

etc.), and

i. amido radicals (e.g.,

wherein R is a hydrogen atom, an alkyl group or an aryl group).

Other active hydrogen-containing groups include substituted and unsubstituted alkylidyne oximido radicals. Photoconductors included in this class can be represented by the following structure:

wherein:

a. Ar and Ar are each a phenyl radical including a substituted phenyl radical such as a halophenyl radical, an alkyl phenyl radical or an aminophenyl radical;

b. Ar, is an arylene radical including a substituted arylene radical such as a phenylene radical or a naphthylene radical;

c. R and R are each hydrogen, a phenyl radical including a substituted phenyl radical or a lower alkyl radical preferably having one to eight carbon atoms;

d. X is either (1) an active hydrogen-containing group such as a carboxy radical, an acyl halide radical, an amido radical, a carboxylic acid anhydride radical, an ester radical, a cyano radical, a hydroxy radical, a semicarbazono radical, an ethynyl radical, or a methylidyne oximido radical, or (2) hydrogen, provided that when X is hydrogen R and R are also hydrogen: and

e. n is an integer ofone to three.

The arylene nucleus can be substituted in any position by the vinyl or vinylene moiety. However, when Ar is phenylene, particularly good results are obtained if the substitution occurs in the para position. These material are more fully described in US. Ser. No. 706,800 filed Feb. 20, 1968, now US. Pat. No. 3,567,450.

I. Triarylamines in which at least one of the aryl radicals is substituted by an active hydrogen-containing groups. The term active hydrogen-containing group" has the same meaning as set forth above and again includes those compounds encompassed by the discussion in the textbook and additionally includes those compounds which contain groups which are hydrolyzable to active hydrogen-containing groups. Typical active hydrogen-containing groups which are substituted on an aryl radical of the triarylamine include:

a. carboxy radicals;

b. hydroxy radicals;

c. ethynyl radicals;

d. ester radicals (e.g.,

0 iii??? where in R is an alkyl or an aryl group);

e. lower alkylene hydroxyl radicals (e.g., having one to eight carbon atoms);

f. carboxylic acid anhydride radicals;

g. lower alkylene carboxy radicals (e.g., having two to eight carbon atoms);

h. cyano radicals;

i. acyl halide radicals e.g.,

etc.);

j. amido radicals (e.g.,

O in a N wherein R is a hydrogen atom, an alkyl group or an aryl group);

k. lower alkylidyne oximido radicals having one to eight carbon atoms including substituted alkylidyne oximido radicals (e.g.,

wherein R is hydrogen or a lower alkyl radical);

l. semicarbazono radicals; and

m. arylene carboxy radicals including substituted arylene carboxy radicals (e.g.,

wherein D, and are phenyl or lower alkyl radicals. Photoconductors included in this class can be represented by the following structure:

wherein:

a. Ar, and Ar, are each a phenyl radical including a substituted phenyl radical such as a halophenyl radical, an alkyl phenyl radical or an amino phenyl radical;

b. Ar is an arylene radical including a substituted arylene radical such as a phenylene radical or a naphthylene radical; and

c. X is an active hydrogen-containing group such as a carboxy radical, an acyl halide radical, an amido radical, a carboxylic acid anhydride radical, an ester radical, a cyano radical, a semicarbazono radical, a hydroxy radical. an ethynyl radical, a methylidyne oximido radical or a phenylene carboxy radical. These material are more fully described in US. Ser. No. 706,780 filed Feb. 20, 1968.

J. Organometallic compounds having at least one aminoaryl substituent attached to a Group We or Group Va metal atom. The metallic substituents of this class of organic photoconductors are Group lVa or Group Va metals in accordance with the Periodic Table of the Elements (Handbook of Chemistry and Physics, 38th edition, pp. 394-) and include silicon, germanium, tin and lead from Group lVaand phosphorus, arsenic, antimony and bismuth from Group Va. These materials can be substituted in the metallo nucleus with a wide variety of substituents but at least one of the substituents must be an amino-aryl radical. The amino radical can be positioned anywhere on the aromatic nucleus. but best results are obtained if the aryl moiety is a phenyl radical having the amino group in the four or para position. Typical substituents attached to the metal nucleus include the following:

a. a hydrogen, sulfur or oxygen atom,

b. an alkyl radical,

c. an aryl radical including unsubstituted as well as substituted aryl radicals such as aminoaryl, alkylaryl and haloaryl,

d. an oxygen-containing radical such as an alkoxy or aryloxy radical,

e. an amino radical including unsubstituted and substituted amino radicals such as monoand diarylamino and monoand dialkylamino radicals,

f. a heterocyclic radical and g. a Group [Va or Va organometallic radical. Photoconductors included in this class can be represented by the following structures:

where E G L and Q can be a. a hydrogen atom,

b. an aryl radical including unsubstituted as well as substituted aryl radicals such as a phenyl radical, a naphthyl radical, a dialkylaminophenyl radical, or a diarylaminophenyl radical,

c. an alkyl radical having one to eight carbon atoms,

d. an alkoxy radical having one to eight carbon atoms,

e. an aryloxy radical such as a phenoxy radical,

f, an amino radical having the formula wherein R and R can be hydrogen atoms or alkyl radicals having one to eight carbon atoms, or

g. a heterocyclic radical having five to six atoms in the hetero nucleus including at least one nitrogen atom such as a triazolyl, a pyridyl radical, etc.; T is an amino radical such as an alkylarnino radical having one to eight carbon atoms or an arylamino radical such as a phenylamino radical; Ar is an aromatic radical such as phenyl or naphthyl;

M and M"2 are the same or different Group lVa metals;

M,, is a Group Va metal;

D, can be any of the substituents set forth above for E G L and Q and in addition can be a Group lVa orzanometallic radical or when taken with E,

atom or a sulfur atom. These materials are described in US. Ser. No. 650,664 filed July 3, 1967.

K. Any other organic compound which exhibits photoconductive properties such as those set forth in Australian Pat. No. 248,402.

Representative organic photoconductors useful in this invention include the compounds listed below:

TABLE I diphenylamine dinaphthylamine N,N'-diphenylbenzidine N-phenyl-l-naphthylmaine N-phenyl-Z-naphthylamine N,N-diphenyl-p-phenylenediamine 2-carboxy-5-chloro-4'-methoxydiphenylamine p-anilinophenol N,N'-di-2-naphthyl-p-phenylenediamine 4, 4-benzylidene-bis-(N,N-dimethyl-m-toluidine) triphenylamine N,N,N',N'-tetraphenyl-m-phenylenedia:mine 4-acetyltriphenylamine 4-hexanoyltriphenylamine 4-lauroyltriphenylamine 4-hexyltriphenylamine 4-dodecyltriphcnylamine 4, 4'-bis(diphenylamino)benzil 4, 4'-bis(diphenylamino)benzophenone polylN,4"-(N,N,N'-triphenylbenzidine)] polyadipyltriphenylamine polysebacyltriphenylamine polydecamethylentriphenylaimne plly-N-O 4-vinylphenyl)diphenylamine poly-N-(vinylphenyl)-a,a'-dinaphthylamine 4, 4-benzylidine-bis(N,N,-diethyl-m-toluidine) 4',4"-diamino4-dimethylamino-Z,2"-dimethyltriphenylmethane 4, "4"-bis(diethylamino)-2, 6-dichloro-2 2"-dimethyltriphenylmethane 4',4"-bis(diethylamino)-2,2"-dimethyldiphenylnaphthylmethane 2',2"-dimethyl-4,4',4"-tris(dimethylamino)triphenylmethane 4',4' '-bis( diethylamino )-4-dimethylamino-2 ,2 "-dimethyltriphenylmethane 4' ,4 -bis( diethylamino )-2-chloro-2 ,2 "-dimethyl-4- dimethylaminotriphenylmethane 4',4 '-bis( diethylamino)-4-dimethylamino-2 ,2 ,2 '-trimethyltriphenylmethane 4',4"-bis(dimethylmaino )-2-chloro-2 ',2 '-dimethyltriphenylmethane 4',4"-bis( dimethylamino )-2 ,2 -dimethyl-4methoxytriphenylmethane Bis(4-diethylamino l l l -triphenylethane Bis( 4 diethylamino )tetraphenylmethane:

4 ,4 "bis( benzylethylamino )-2',2' -dimethyltriphenylmethane 4',4 '-bis( diethylmaino )-2,2 '-diethoxytriphenylmethane 4,4-bis(dimethylamino)-l ,l l -triphenylethane l-(4-N,N-dimethylaminophenyl)-l l -diphenylethane 4-dimethylaminotetraphenymethane 4-diethylaminotetraphenylmethane 4,4'-bis (diphenylamino) chalcone 4-diphenylamino-4'-dimethylaminochalcone 4-dimethylamino-4'-diphenylaminochalcone 4,4-bis (dimethylamino) chalcone 4,4'-bis (diethylamino) chalcone 4-diethylamine4 -diphenylaminochalcone 4,4 (n-amyloxy) chalcone 4,4'-bis( nitro )chalcone 4-diphenylaminochalcone 4-dimethylaminochalcone diazabenzo(b)fluorene, 3,l3-dioxo- 7-oxadibenzo(b,g)fluorene, and the like; 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, and salicyclic acid; sulfonic and phosphoric acids; and various dyes, such as cyanine (including carbocyanine), mercoycanine, 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 including selenapyrylium and thiapyrylium salts, and cyanine 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 element. Other methods of incorporating the sensitizer of 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 that can be added to a photoconductorincorporating layer to give effective increases in speed can vary widely. The optimum concentration in any give case will vary with the specific photoconductor and sensitizing compound used. In general, substantial speed gains can be ob tained where an appropriate sensitizer is added in a concentration range from about 0.0001 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.

Solvents useful for preparing coating compositions with the binders of the present invention can include a wide variety of organic solvents for the components of the coating composition. For example, benzene; toluene; acetone; Z-butanone; chlorinated hydrocarbons such as methylene chloride; ethylene chloride; and the like; ethers, such as tetrahydrofuran and the like, or mixtures of such solvents can advantageously be employed in the practice of this invention.

In preparing the coating compositions utilizing the binders 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 ofphotoconductive 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 coating the photoconductive layers ofthe present invention can include any of the electrically conducting supports, for example, paper (at a relative humidity above percent); aluminum-paper laminates; mptal fnile cnr'h 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 or 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 film support material such as poly(ethylene terephathalate) 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 maleic anhydride and a vinyl acetate: polymer, cuprous iodide and the like. Such conducting layers and methods for their optimum preparation and use are disclosed in U.S. 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 photoconduo 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 electrostatic charge 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 lightstruck areas to be conducted away from the surface in proportion to the intensity ofthe illumination. in a particular area.

The charge pattern produced by exposure is then developed or transferred to another surface and developed there, i.e., either the charge 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 a latent 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 thefollowing U.S. Pats: Nos. 2,786,439; 2,786,440.; 2,786,441; 2,811,465; 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, US. Pat. No. 2,297,691 and in Australian Pat. No. 212,315.1n 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. 15 (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 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 the same or different application for the electrophotographic element.

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

EXAMPLE l 1.5 grams of 4,4-isopropylidenebisphenoxyethyl-cotrimetylene terephthalate) binder containing 0.5 grams of 4,4'-benzylidine-bis(N,N-diethyl-m-toluidine) photoconductor and .04 grams of 2,4-(4-ethoxypheny1)-6(4-n-amlyoxystryl) pyrylium fluoroborate sensitizer are dissolved in 15.6 grams of methylene chloride by stirring the solids in the solvent for one hour at room temperature. The resulting solution is hand coated at a wet coating 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 block is maintained at a temperature of 90 F. After drying, the electrophotographic element is charged under positive corona source until the surface potential, as measured by an electrometer probe, reaches about 600 volts. It is then subjected to exposure from behind a stepped density gray scale to a 3000 K. tungsten source. The exposure causes reduction of the surface potential of the element under each step of the gray scale from its initial potential, V,, to some lower potential, V, whose exact value depends on the actual amount of exposure in meter-candle-seconds 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 shoulder speed is the numerical expression of multiplied by the reciprocal of the exposure in meter-candle-seconds required to reduce the 600 volt charged surface potential by 100 volts. The toe speed is the numerical expression of IO multiplied by the reciprocal of the exposure in meter-candle-seconds required to reduce the 600 volt charged surface potential to 100 volts. This coating is found to have a positive 100 V. toe speed of 180. Similar results are obtained when 0.5 gram of bis(4- diethylamino)-l, l,l-triphenylethane or 0.5 gram of bis(4- diethylamino)tetraphenylmethane are used as photoconductors in place of the 4,4 -benzylidine bis(N,N-diethyl mtoluidine) for both positive and negative charging. 30

EXAMPLE 2 Example 1 is repeated except the binder employed is poly(4,4-isopropylidenebisphenoxyethyl-co-ethylene terephthalate). This binder does not fall within the scope of the invention since the alkylene moiety (i.e., 2) has only two carbon atoms and is included for comparison purposes only. The coating has a positive l00-volt toe speed of 128.

The following examples 3-5 are identical to example 1 except for the binder employed. 1.5 grams of various binders are used in each of the following examples. In each case a significant improvement is noted in the l00-volt toe speeds over binders of the type described in the preceding example.

EXAMPLE 6 The coating compositions of Examples 1 and 3-5 are again coated in the manner described in example 1. In a darkened room, the surface of each of the photoconductive layers 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 lS developed in the usual manner by cascading over the surface of the layer a mixture of negatively charged black thermoplastic toner particles and glass beads. A good reproduction of the pattern results in each instance EXAMPLE 7 The copolyesters described herein are made by standard melt condensation techniques. Poly(4 4'-isopropylidenebisphenoxyethyl-co-tetramethylene terephthalate) is prepared by mixing 0.15 moles of dimethyl terephthalate, 0.075 moles of 4,4-isopropylidenebisphenoxyethanol, 0.10 moles of tetramethylene glycol and 0.05 grams of tetrabutyl orthotitanate. Nitrogen is bubbled through the mixture, and it is heated at 200 C. for 2 hours to distill off methanol. The temperature is raised to 250 C. and vacuum applied until complete polymerization is completed. The resultant polymer contains 50 percent of repeating unit A and 50 percent B. The other polymers are prepared by the same method by replacing tetramethylene glycol with the appropriate compound. For example, trimethylene glycol would be used to prepare polymer 1, pentamethylene glycol for polymer 3, diethylene glycol for compound 4, etc.

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 effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

lclaim:

1. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising a photoconductor and a binder for said photoconductor comprising a polyester having repeating units of wherein Z is an alkylene group having three to ten carbon atoms, and D and E are each selected from the group consisting of a hydrogen atom, a halogen atom, an aryl group, an alkyl group, an aryloxy group and an alkoxy group.

2. The electrophotographic element of claim 1 wherein Z is selected from the group consisting of a. a straight chain alkylene hydrocarbon radical,

b. an oxydialkylene radical,

c. an alkylene bis(oxyalkylene) radical,

d. a cycloalkylene hydrocarbon radical,

e. a branched chain alkylene hydrocarbon radical,

f. a thiadialkylene radical and g. an alkylene bis(thiaalkylene) radical.

3. The electrophotographic element of claim 1 wherein the photoconductive composition contains a sensitizer selected from the group consisting of cyanine and pyrylium dye salts.

d. An electrophotographic element comprising a support having coated thereon a photoconductive composition com prising an organic photoconductor, a sensitizer and a binder for said photoconductor and sensitizer, comprising a random, linear copolyester having repeating units of and wherein Z is an alkylene group having three to ten carbon atoms, and D and E are each selected from the group consisting of a hydrogen atom, a halogen atom, an aryl group, an alkyl group, an aryloxy group and an alkoxy group.

5. The electrophotographic element of claim 4 wherein Z is selected from the group consisting of t is an integer from one to seven;

n and are each integers from two to seven; u and v are each integers from zero to five; p, q and r are each integers from two to six;

s is an integer from one to seven when R and R is hydrogen;

s is an integer from zero to seven when R or R is an alkyl radical;

D is selected from the group consisting of an oxygen atom and a sulfur atom;

Q represents the atoms necessary to complete a three-to-six carbon atom cycloalkyl radical; and

R R R and R are each selected from the group consisting of hydrogen and an alkyl radical having one to five carbon atoms.

6. The electrophotographic element of claim 4 wherein the sensitizer is selected from the group consisting of carbocyanine, pyrylium, thiapyrylium and sel enapyrylium dye salts.

7. The electrophotographic element of claim 4 wherein the organic photoconductor is 4,4'-benzy'lidenebis(N,N-diethylm-toluidine).

3. The electrophotographic element of claim 4 wherein the binder has 20 percent to percent of repeating unit A.

9, The electrophotographic element of claim 4 wherein the binder has 30 percent to 60 percent of repeating unit A.

10. The electrophotographic element ofclaim 4 wherein the binder is poly(4,4'-isopropylidenebisphenoxyethyl-cotrimethylene terephthalate).

11. The electrophotographic element ofclaim 5 wherein the binder is poly(4,4'-isopropylidenebis-phenoxyethyl-co-tetramethylene terephthalate).

12. The electrophotographic element ofclaim 5 wherein the binder is poly(4,4"isopropylidenebisphenoxyethyl-co-pentamethylene terephthalate).

13. The electrophotographic element ofclaim 5 wherein the binder is poly(4,4'-isopropylidenebisphenoxy-co-oxydiethylterephthalate).

14. An electrophotographic element comprising a support having coated thereon a photoconductive composition com prising 10 to about 60 weight percent of 4,4- benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4'-isopropylidenebisphenoxyethyl-co-trimethylene terephthalate) as a binder for said photoconductive composition.

15. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4" benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4'-isopropylidenebisphenoxyethyl-co-tetreamthylene terephthalate) as a binder for said photoconductive composition.

16. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4- benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4-isopropylidenebisphenoxyethyl-co-pentamethylene terephthalate) as a binder for said photoconductive composition.

17. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4- benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4'-isopropylidenebisphenoxyethyl-co-oxydiethyi terephthalate) as a binder for said photoconductive composition.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,6l5, +06 Dated October 26, 197].

Inventor(s) Stewart H. Merrill It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 37, delete "by a photoconductive composition which"; line 38, delete "contains a photoconduotor; line 5 4, "in" should read is"; lines 67-75, in formula A, the brackets and the letter "E" are not properly printed.

Column 2, line 20, in formula, "R is not print ed properly in the patent; line 56 "cyclohexylenediemthylene" should read "cyclohexylenedimethylene"; line 58, tylenediemthylene" should read "tylenedimethylene"; line 7 insert --terephthalate)--; line 75, insert --2. Poly( +-isopropylidenebisphenoxyethylo -tetramethylene terephthalate)--.

Column 3, line 6, delete --phthalate)-- line &5, "ventions" should read "ventiotf; line #6, insert --A. Arylamine photoconductors including substituted and unsubstituted arylamines, diarylamines, nonpolymerio triarylamines and polymeric triarylamines such as those described in U. S. Patents 3,2 +O,597 and 3,l80,730.-- line 56, butryl should read butyryl".

Column line 2, before alkoxy" insert --an--- line 2 "nitrate should read nitro"; line 7 l,l,l--triarylakanes should read "1,1 ,l-triarylalkanes"; line 10, "moeties should read "moieties"; line Q0, groups, should read group,

F22 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Paz m; N 3,6l5, IO6 Dated October 26, 1971 Inventor(s) Stewart ll 2 Q It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 50, in formula, I O is not printed H --CH=CH--C-R properly in the patent.

Column 5, line 29, delete "nucleus and 8nucleus; 1967,"; line 65, "on" should read "one".

Column 6, line 52, "(CH=CH) should read"-(CH=CHJ- Column 7, line 55, "material" should read "materials"; line 59, "groups" should read "group".

Column 8, line 1, "hydroxyl" should read "hydroxy".

Column 10, line 1, before the first "atom" insert --an oxygen atom or a sulfur atom; J can be any of the substituents set forth above for E G L and Q and in addition can be when taken with E, an oxygen--- line EA "naphthylmaine" should read naphthylamine"; line 33, "polydecamethylentriphenylaimne" should read "polydecamethylentriphenylamine"; line 34,

"plly-N- )h-vinylphenyl)diphenylamine" should read poly-N-(Q-Vinylphenyl)diphenylamine"; line 39, i, bis(diethylamino)-2, should read "LI, '4"-bis(diethylamino)-2, line 51, "4' ,4"-bis(dimethylmaino)"should read "4' ,4"- bis(dimethylamino); line 70, b 4' (n-amyloxy)chalcone" should read 5H '-bis(n-amyloxy)chalcone".

P040551 UNITED STATES PATENT OFFICE m CERTIFICATE OF CORRECTION Patent No. 3 ,615 ,'-+O6 Dated October 26 197].

Inventor(s) Stewart H. Merrill 3 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10, line 7 4, insert I'-dipheny1aminocha1cone--; line 75, insert +'-dimethylaminocha1cone--; line 76 insert --bis-[5-(5I-L-dibenzo[a,d7cycloheptenyl7ether--.

Column 11, line 2, "dioarbomethoxyl-" should read "dicarbomethoxy-"; line 14, "dimenthylamino-" should read "dimethylamino-; line l9,"cycloheptatrien" should read "cycloheptatriene"; line 31, "NSfuryl-N-(Z-methyl- +hydroxypenyl)" should read 'N--3-f\.1".."yl-N-(Z-meth l- -I- hydroxyphenyl)"; line 35, "tolyhydrazine should read "tolylhydrazine".

Column 12 line 18 "propen-lol" should read "propen-l-ol"; line 7 "3,150,615" should read "3,250,615"; line 75, "5,lO,dix0xo-4a, should read "5,lO,dioxo-4a,".

Column 13, line 22, "of" appearing second time in line should read "or"; line 33, "give" should read given".

Column l I, line 3, "or" should read "on".

Column 15 line 20, "trimetylene" should read "trimethylene"; line 5 4, delete 3O.

P0-1050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3,6l5, +O6 Dated October 26, 1971 Inventor) Stewart H. Merrill 4 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 16, in claim 1, the portion of formula B,

EIH -CH -C- should read {CH -CH -O- Column 17, in claim the portion of formula B CH CH l3 l3 -O- should read -C- 1 I CH CH Column 17 in claim 5, the portion of formula (21) -C should read -C- 73 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,6lS IO6 Dated October 26, 1.971

Inventor(s) Stewart Merrill 5 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 18, line 25 of claim ll, "5" should read line 28 of claim 12, "5" should read "4''; line 31 of claim 13, "5" should read I"; line 32 of claim 13, "isopropylidenebispheno ry-" should read "isopropylidenebisphenoxyethyl-"; line +8 of claim 15, "tetreamthylene" should read "trimethylene".

Signed and sealed this 13th day of March 1973.

LEAL) test:

WARD M.I-LI3TCHER,JR. ROBERT GOTTSCHALK testing Officer Commissioner of Patents

Claims

2. The electrophotographic element of claim 1 wherein Z is selected from the group consisting of a. a straight chain alkylene hydrocarbon radical, b. an oxydialkylene radical, c. an alkylene bis(oxyalkylene) radical, d. a cycloalkylene hydrocarbon radical, e. a branched chain alkylene hydrocarbon radical, f. a thiadialkylene radical and g. an alkylene bis(thiaalkylene) radical.
3. The electrophotographic element of claim 1 wherein the photoconductive composition contains a sensitizer selected from the group consisting of cyanine and pyrylium dye salts.
4. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising an organic photoconductor, a sensitizer and a binder for said photoconductor and sensitizer, comprising a random, linear copolyester having repeating units of
5. The electrophotographic element of claim 4 wherein Z is selected from the group consisting of
6. The electrophotographic element of claim 4 wherein the sensitizer is selected from the group consisting of carbocyanine, pyrylium, thiapyrylium and selenapyrylium dye salts.
7. The electrophotographic element of claim 4 wherein the organic photoconductor is 4,4''-benzylidenebis(N,N-diethyl-m-toluidine).
8. The electrophotographic element of claim 4 wherein the binder has 20 percent to 80 percent of repeating unit A.
9. The electrophotographic element of claim 4 wherein the binder has 30 percent to 60 percent of repeating unit A.
10. The electrophotographic element of claim 4 wherein the binder is poly(4,4''-isopropylidenebisphenoxyethyl-co-trimethylene terephthalate).
11. The electrophotographic element of claim 5 wherein the binder is poly(4,4''-isopropylidenebisphenoxyethyl-co-tetra-methylene terephthalate).
12. The electrophotographic element of claim 5 wherein the binder is poly(4,4''-isopropylidenebisphenoxyethyl-co-pentamethylene terephthalate).
13. The electrophotographic element of claim 5 wherein the binder is poly(4,4''-isopropylidenebisphenoxy-co-oxydiethylterephthalate).
14. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4''-benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4''-isopropylidenebisphenoxyethyl-co-trimethylene terephthalate) as a binder for said photoconductive composition.
15. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4''-benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4''-isopropylidenebisphenoxyethyl-co-tetreamthylene terephthalate) as a binder for said photoconductive composition.
16. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4''-benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4''-isopropylidenebisphenoxyethyl-co-pentamethylene terephthalate) as a binder for said photoconductive composition.
17. An electrophotographic element comprising a support having coated thereon a photoconductive composition comprising 10 to about 60 weight percent of 4,4''-benzylidinebis(N,N-diethyl-m-toluidine) as an organic photoconductor, 0.005 to about 5.0 weight percent of a sensitizer for said photoconductor and poly(4,4''-isopropylidenebisphenoxyethyl-co-oxydiethyl terephthalate) as a binder for said photoconductive composition.