United States Patent to 11, 4,018,606 Contois et al. 45 Apr. 19, 1977 (54) ORGANIC AZO PIGMENT SENSITIZERS FOR PHOTOCONDUCTIVE LAYERS R ph C 2 x (75) Inventors: Lawrence E. Contois; Joseph Y. R2 NEN-C Kaukeinen; Stephen Michel; Thomas C M. Plutchak, all of Rochester, N.Y. R R

(73) Assignee: Eastman Kodak Company, wherein X consists of the atoms necessary to complete Rochester, N.Y. a naphthalene, anthracene, or OH (22 Filed: May 3, 1974 C 2 N. -C N N (21) Appl. No.: 466,658 =N R

(52) U.S. Cl...... 96/1.7; 96/1.6 ring; (51) Int. Cl”...... G03G 5/09 (58) Field of Search ...... 96/1, 1.5, 1.6 R', R', and R are hydrogen, halogen, alkoxy, NO, alkyl, SOH or alkali metal salts thereof,

(56) References Cited O O UNITED STATES PATENTS rCNH NO, and -CNH 3,384,632 5/1968 Solodar ...... 96/1.6 3,622,341 8/1969 Lee ...... 96/1.6 and COOH or alkali metal salts thereof, and Rand R8 3,684,548 8/1972 Contois ...... 96/1.6 can comprise the atoms necessary to complete a 3,775,105 l/1973 Kukla ...... 96/1.6 phenyl, naphthyl or anthryl ring; and R is selected from FOREIGN PATENTS OR APPLICATIONS the group consisting of 1,370,197 10/1974 United Kingdom ...... 96/1.5 O O H il H Primary Examiner-David Klein 8-i-O-No, 8-N-O). or COOM Assistant Examiner-John L. Goodrow Attorney, Agent, or Firm-Arthur H. Rosenstein where M is alkyl, alkali or alkaline earth metal are useful as sensitizers for photoconductive compositions in electrophotographic processes. 57 ABSTRACT A class of organic pigments having the formula 23 Claims, No Drawings 4,018,606 1. 2. sure time; it makes possible the recording of a wide ORGANIC AZO PIGMENT SENSITIZERS FOR range of colors in proper tonal relationship, and allows projection printing through various optical systems. By PHOTOCONDUCTIVE LAYERS increasing the speeds through the use of sensitizers, The process of xerography, as disclosed by Carlson in photoconductors which would otherwise have been U.S. Pat. No. 2,297,691, employs an electrophoto unsatisfactory are useful in processes where high graphic element comprising a support material bearing speeds are required such as document copying. a coating of a normally insulating material whose elec Various pigment particles are described in the prior trical resistance varies with the amount of incident art as useful photoconductors. The use of substituted actinic radiation it receives during an imagewise expo O 2,4-diaminotriazines as electrically photosensitive par sure. The element, commonly termed a photoconduc ticles in photoelectrophoretic imaging and in conven tive element, is first given a uniform surface adaptation. tional xerographic processes is described in U.S. Pat. It is then exposed to a pattern of actinic radiation which No. 3,445,227. U.S. Pat. Nos. 3,447,922 and 3,448,028 has the effect of differentially reducing the potential of describe the use of N-substituted-3,13-dioxodinaph the surface charge in accordance with the relative en 15 tho(2,1-b',2',3'-d)-furan-6-carboxamides as photosen ergy contained in various parts of the radiation pattern. sitive particles in xerographic processes. These photo The differential surface charge of electrostatic latent conductors in themselves are not sensitive at the longer image remaining on the electrophotographic element is wavelength portion of the visible spectrum. then made visible by contacting the surface with a A large number of acidic compounds have been de suitable electroscopic marking material. Such marking 20 scribed as sensitizers for photoconductive composi material or toner, whether contained in an insulating tions such as in U.S. Pat. No. 3,316,087 and French liquid or on a dry carrier, can be deposited on the Pat. No. 1,288,392. The search for materials which exposed surface in accordance with either the charge enhance the sensitization of a broad range of photocon pattern or the absence of charge pattern as desired. ductors is a continuing one. . . . The deposited marking material may then be either 25 It is, therefore, an object of this invention to provide permanently fixed to the surface of the sensitive ele novel sensitized photoconductive compositions. ment by known means such as heat, pressure, solvent It is another object of this invention to provide novel vapor, or the like, or transferred to a second element to sensitized photoconductive elements. which it may similarly be fixed. Likewise, the electro It is a further object of this invention to provide a static latent image can be transferred to a second ele 30 process for using novel sensitized, photoconductive ment and developed there. elements. . . Various photoconductive insulating materials have These and other objects are accomplished with pho been employed in the manufacture of electrophoto toconductive compositions containing a photoconduc graphic elements. For example, vapors of selenium and tor and a sensitizing amount of a specific class of or vapors of selenium alloys deposited on a suitable sup 35 ganic pigments. Electrically insulating polymeric bind port and particles of photoconductive zinc oxide held ers are generally added with non-polymeric photocon in a resinous, film-forming binder have found wide. application in present-day document copying applica ductors. tions. The organic pigment sensitizers of this invention Since the introduction of electrophotography, a great 40 have the formula: many organic compounds have also been screened for their photoconductive properties. As a result, a very R1 ph large number of organic compounds are known to pos Cn 2 sess some degree of photoconductivity. Many organic R2 NEN-C X compounds have revealed a useful level of photocon 45 N duction and have been incorporated into photoconduc C tive compositions. Optically clear organic photocon R3 ductor containing elements having desirable electro photographic properties can be especially useful in electrophotography. Such electrophotographic ele SO wherein: ments may be exposed through a transparent base if X consists of the atoms necessary to complete a desired, thereby providing unusual flexibility in equip naphthalene, anthracene or ment design. Such compositions, when coated as a film or layer on a suitable support also yield an element gh which is reusable; that is, it can be used to form subse 55 2 N quent images after residual toner from prior images has -C N been removed by transfer and/or cleaning. N Although some of the photoconductors comprising C=N V. the materials described are inherently light-sensitive, R their degree of sensitivity is usually low and in the short 60 wavelength portion of the spectrum so that it is com mon practice to add materials to increase the speed and R, R', and Rare independently selected from the to shift the sensitivity toward the longer wavelength. group consisting of hydrogen, halogen, such as chlo portion of the visible spectrum. Increasing the speed rine, bromine, fluorine or iodine, alkoxy, preferably and shifting the sensitivity of such systems, into the 65 containing 1 to 8 carbon atoms such as methoxy, eth visible region of the spectrum has several advantages: it oxy, propoxy, and the like, including substituted alkoxy makes available inexpensive and convenient light such as aminoalkoxy, haloalkoxy, and the like; NO, sources such as incandescent lamps; it reduces expo alkyl, preferably containing from 1 to 8 carbon atoms 4,018,606 3 such as methyl, ethyl, propyl, butyl, isopentyl, hexyl NO, . and the like; SOH or alkali metal salts thereof such as SONa, SOK, and the like; and COOH or alkali metal, salts thereof such as COONa, COOK, and the like . . . OCH 5

(C)ON O R” and R can, taken together, also comprise the atoms necessary to complete a phenyl, naphthyl, or anthryl ring. The above organic pigments produce an enhanced R is selected from the group consisting of sensitization effect, when used in a photoconductive 15 composition containing photoconductors in compari son to the sensitization of (A) photoconductor compo sitions without the sensitizers, (B) photoconductive compositions containing only the pigments without an independent photoconductor, and (C) photoconduc on-G), co-(O) 20 tive compositions containing a photoconductor and similar pigments outside the scope of this invention. or COOm wherein M is alkyl preferably containing The enhanced sensitization is evidenced by greater from 1 to 8 carbon atoms such as methyl, ethyl, isopro electrical speeds. A suitable method of increasing elec pyl, butyl, hexyl, octyl, and the like; alkali metals such trical speed is described more fully in the appended as Li, Na, K, Rb and Cs; and alkaline earth metals such 25 examples. as Ca, Sr., Ba, and the like. Preferred binders for use in preparing the present It is noted that the term alkyl used throughout the photoconductive layers comprise polymers having specification and claims is meant to include substituted fairly high dielectric strength which are good electri alkyl such as chloroalkyl, aralkyl, and the like. Gener cally insulating film-forming vehicles. Materials of this ally, any substituent may be used on the alkyl that does 30 type comprise styrene-butadiene copolymers; silicon not adversely affect the sensitizing properties of the resins; styrene-alkyd resins; silicon-alkyd resins; soya pigment. alkyd resins; poly(vinyl chloride); poly(vinylidene Some preferred pigment sensitizers of this invention chloride); vinylidene chloride-acrylonitrile copoly mers; poly(vinyl acetate); vinyl acetate-vinyl chloride

NO, HO O O C-N H ll NaC NSN O-CH (O)

copolymers; poly(vinyl acetals), such as poly(vinyl 50 butyral); polyacrylic and methacrylic esters, such as poly(methylmethacrylate), poly(n-butylmethacrylate), poly(isobutylmethacrylate), etc. polystyrene, nitrated polystyrene; polymethylstyrene, isobutylene polymers; (Pigment Violet RB manufactured by Roma Chemi polyesters, such as poly(ethylenealkaryloxyalkylene cals) 55 terephthalate), phenol-formaldehyde resins; ketone resins; polyamides, polycarbonates; polythiocarbon SONa HO COONa ates, poly(ethyleneglycol-co-bishydroxyethoxyphenyl propane terephthalate); etc. Methods of making resins of this type have been described in U.S. Pat. Nos. 60 2,361,019 and 2,258,423. Suitable resins of the type contemplated for use in the photoconductive layers of the invention are sold under such trade names as Vitel PE-101, Cymac, Piccopale 100, Saran F-200 and Lexan 105. Other types of binders which can be used in 65 the photoconductive layers of the invention include such materials as paraffin, mineral waxes, etc. The (Harrison Red pigment manufactured by Harmon Col binders are generally used with the inorganic photo ors) conductors. 4,018,606 5 The sensitizers of this invention improve the electri cal speeds of compositions containing a wide variety of photoconductors including inorganic photoconductors such as selenium, zinc oxide, titanium oxide, cadmium sulfide, lead oxide, cadmium selenide and the like and organic photoconductors including organometallic wherein each of D, E and G is an aryl group and J is a photoconductors. hydrogen atom, an alkyl group, or an aryl group, at Typical photoconductors useful herein are described least one of D, E and G containing an amino substitu below. 10 ent, the aryl groups attached to the central carbon A. Arylamine photoconductors including substituted atom being preferably phenyl groups, although naph and unsubstituted arylamines, diarylamines, nonpoly thyl groups can also be used including substituted aryl meric triarylamines and polymeric triarylamines such groups containing substituents such as alkyl and alkoxy as those described in U.S. Patent Nos. 3,240,597 and typically having 1 to 8 carbon atoms, hydroxy, halogen, 3, 180,730. 15 etc, in the ortho, meta or para positions, ortho-sub B. Photoconductors represented by the formula: stituted 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 rep le-z-so 20 Z' resented by the formula: wherein Z represents a mononuclear or polynuclar divalent aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, binaphthyl, etc), or a sub 25 stituted divalent aromatic radical of these types wherein said substituent can comprise a member such wherein each R can be an alkyl group typically having 1 to 8 carbon atoms, a hydrogen atom, an aryl group, or as an acyl group having from 1 to about 6 carbon atoms together, the necessary atoms to form a heterocyclic (e.g., acetyl, propionyl, butyryl, etc), an alkyl group 30 amino group typically having 5 to 6 atoms in the ring having from 1 to about 6 carbon atoms (e.g., methyl, such as morpholino, pyridyl, pyrryl, etc; at least one of ethyl, propyl, butyl, etc), an alkoxy group having from D, E and G preferably being a p-dialkylaminophenyl 1 to about 6 carbon atoms (e.g., methoxy, ethoxy, group, when J is an alkyl group, such an alkyl group propoxy, pentoxy, etc), or a nitro group; Z represents more generally has 1 to 7 carbon atoms, these materials a mononuclear or polynuclear monovalent or polynu 35 being more fully described in U.S. Pat. No. 3,274,000, clear monovalent aromatic radical, either fused or lin French Pat. No. 1,383,461 and in U.S. application Ser. ear (e.g., phenyl, naphthyl, biphenyl, etc); or a substi No. 627,857, filed Apr. 3, 1967 by Seus and Goldman, tuted monovalent aromatic radical wherein said sub now U.S. Pat. No. 3,542,544. stituent can comprise a member such as an acyl group 40 D. Photoconductors comprising 4-diarylamino-sub having from 1 to about 6 carbon atoms (e.g., acetyl, stituted chalcones having the formula: propionyl, butyryl, etc), an alkyl group having from 1 to about 6 carbon atoms (e.g., methyl, ethyl, propyl, butyl, etc), an alkoxy group having from 1 to about 6 carbon atoms (e.g., methoxy, propoxy, pentoxy, etc), 45 CH=CH-C-R, or a nitro group; Q can represent a hydrogen atom or an aromatic amino group, such as Z'NH-; b represents an integer from 1 to about 12, and L represents a hy wherein: drogen atom, a mononuclear or polynuclear aromatic R1 and R2 are each phenyl radicals including substi radical either fused or linear (e.g., phenyl, naphthyl 50 tuted phenyl radicals, R. preferably having the formula: biphenyl, etc), a substituted aromatic radical wherein said substituent comprises an alkyl group, an alkoxy group, an acyl group, or a nitro group, or a poly(4'- vinylphenyl) group which is bonded to the nitrogen 55 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 wherein: bases of diaryl or triarylmethane dye salts, 1,1,1-triary 60 Ra and R4 are each aryl radicals, aliphatic residues of lalkanes wherein the alkane moiety has at least two 1 to 12 carbon atoms such as alkyl radicals preferably carbon atoms and tetraarylmethanes having an amino having 1 to 4 carbon atoms, or hydrogen; particularly group substituted in at least one of the aryl nuclei at advantageous results being obtained when R is a tached to the alkane and methane moieties of the latter 65 phenyl radical including a substituted phenyl radical two classes of photoconductors which are nonleuco and where R is diphenylaminophenyl, dimethylamino base materials; and also other polyarylalkanes included phenyl or phenyl, these materials being more fully de by the formula: scribed in Fox U.S. Pat. No. 3,526,501. 4,018,606 7 8 E. Non-ionic cycloheptenyl compounds which may four substituents are not unsubstituted phenyl radicals, be substituted with substituents such as (a) an aryl i.e., if at least one substituent is a substituted phenyl radical including substituted as well as unsubstituted radical or a heterocyclic radical having 5 to 6 atoms in aryl radicals, (b) a hydroxy radical, (c) a heterocyclic the hetero nucleus. Other tetrasubstituted hydrazines radical, (d) a heterocyclic radical having 5 to 6 atoms include those having the following formula: in the heterocyclic nucleus and at least one hetero nitrogen atom, and including substituted and unsubsti tuted heterocyclic radicals, and (e) an oxygen linked DN cycloheptenyl moiety. The substitution on the cyclo heptenyl nucleus occurs at an unsaturated carbon atom O when the cycloheptenyl moiety is a conjugated triene wherein D, E, G and J are each either with no aromatic structure fused thereto. However, if a. a substituted phenyl radical such as a naphthyl there is at least one aromatic structure fused to the radical, an alkylphenyl radical, a halophenyl radi cycloheptenyl moiety, then the substituents are at cal, a hydroxyphenyl radical, a haloalkylphenyl tached to a saturated carbon atom. Additional photo 15 radical or a hydroxyalkylphenyl radical or conductors within this class are included in one of the b. a heterocyclic radical such as an imidazolyl radi following formulae: cal, a furyl radical or a pyrazolyl radical. In addition, J and E can also be c. an unsubstituted phenyl radical. 20 Especially preferred are those tetra-substituted hydra zines wherein both D and G are either substituted phenyl radicals or heterocyclic radicals. These com pounds are more fully described in U.S. Pat. No. 25 3,542,546. where E and G can be either: G. Organic compounds having a 3,3'-bisaryl-2- a. a phenyl radical, pyrazoline nucleus which is substituted in either five b. a naphthyl radical, member ring with the same or different substituents. c. a heterocyclic radical having 5 to 6 atoms in the The 1 and 5 positions on both pyrazoline rings can be heterocyclic nucleus and at least 1 hetero nitrogen 30 substituted by an aryl moiety including unsubstituted as atom, well as substituted aryl substituents such as alkoxyaryl, d. a hydroxyl radical, or alkaryl, alkaminoaryl, carboxyaryl, hydroxyaryl and e. an oxygen-containing radical having a structure haloaryl. The 4-position can contain hydrogen or un such that the resultant cycloheptenyl compound is substituted as well as substituted alkyl and aryl radicals a symmetrical ether; 35 such as alkoxyaryl, alkaryl, alkaminoaryl, haloaryl, D, can be any of the substituents defined for E and hydroxyaryl, alkoxyalkyl, aminoalkyl, carboxyaryl, hy G. above and is attached to a carbon atom in the cyclo droxyalkyl and haloalkyl. Other photoconductors in heptenyl nucleus having a double bond; (R and Rio), this class are represented by the following structure: (R and R), (Rs and Rs), and (R and Rs) are to gether the necessary atoms to complete a benzene ring 40 fused to the cycloheptenyl nucleus; these compounds ' being more fully described in U.S. application Ser. No. 654,091, filed July 18, 1967. of is F. Compounds containing an J-CT-L* N- N N. L'-C-J'-- ". 45 N N D D' nucleus including (1) unsubstituted and substituted N,N-bicarbazyls N-bicarbazyls containing substituents wherein: in either or both carbazolyl nuclei such as: 50 Da, Da', Ja and Ja' can be either a phenyl radical a. an alkyl radical including a substituted alkyl radi including a substituted phenyl radical such as a tolyl cal such as a haloalkyl or an alkoxyalkyl radical, radical or a naphthyl radical including a substituted b. a phenyl radical including a substituted phenyl naphthyl radical. radical such as a naphthyl, an aminophenyl or a E3, Ea', Ga, Gs', La and La" can be any of the substitu hydroxyphenyl radical, 55 ents set forth above and in addition can be either a c. a halogen atom, hydrogen atom or an alkyl radical containing 1 to 8 d. an amino radical including substituted as well as carbon atoms. These organic photoconductors are unsubstituted amino radicals such as an alkylamino more fully described in U.S. Pat. No. 3,527,602. or a phenylalkylamino radical, H. Triarylamines such as those described in U.S. Pat. e. an alkoxy radical, 60 No. 3, 180,730 and those in which at least one of the f, a hydroxyl radical, aryl radicals is substituted by an active hydrogen-con g. a cyano radical, taining group or a vinyl or vinylene radical having at h, a heterocyclic radical such as a pyrazolyl, a car least one active hydrogen-containing group. These bazolyl or a pyridyl radical; materials are more fully described in U.S. Pat. No. or (2) tetra-substituted hydrazines containing substitu 65 3,658,520, issued Apr. 25, 1972. ents which are substituted or unsubstituted phenyl radi I. Organic-metallic compounds having at least one cals, or heterocyclic radicals having 5 to 6 atoms in the amino-aryl substituent attached to a Group IVa or hetero nucleus, suitable results being obtained when all Group Va metal atom such as silicon, germanium, tin

w

4,018,606 1. 12 1, 1'-dihydroxy-9,9'-bicarbazolyl 4-formyltriphenylamine semicarbazone . . . . 2,2'-dicyano-9,9'-bicarbazolyltetra(p-diethylamino triphenyl-p-diethylaminophenylsilane . . . phenyl)hydrazine(p-diethylaminophenyl)hydra methyl-diphenyl-p-diethylaminophenylsilane Ze striphenyl-p-diethylaminophenylgermane . . . 3,3'-bis(1,5-diphenyl-2-pyrazoline) 5 triphenyl-p-dimethylaminophenylstannane : 3,3'-bis-(1-p-tolyl-5-phenyl-2-pyrazoline) triphenyl-p-diethylaminophenylstannane . . 3,3'-bis(1,5-1-naphthyl)-2-pyrazoline) . . diphenyl-di-(p-diethylaminophenyl)stannane 1,5-diphenyl-3-3'-(1'-p-tolyl-5-phenyl)-2'- triphenyl-p-diethylaminophenylplumbane : :". pyrazolyl)-2-pyrazoline. - tetra-p-diethylaminophenylblumbane a 3,3'-bis(1,5-diphenyl-4,5-dimethyl-2-pyrazoline) O phenyl-di-(p-diethylaminophenyl)phosphine. 3,3'-bis(1,4,5-triphenyl-2-pyrazoline bis(p-diethylaminophenyl)phosphine oxide 3,3'-bis(1,5-di-p-tolyl-4-methoxy-2-pyrazoline) tri-p-dimethylaminophenylarsine 3,3'-bis(1,5-diphenyl-4-dimethylamino-2-pyrazo tri-p-diethylaminophenylarsine line) 2-methyl-4-dimethylaminophenylarsine oxide 3,3'-bis 1,5-diphenyl-4-(p-chlorophenyl)-2-pyrazo- 15 tri-p-diethylaminophenylbismuthine a line methyl-di-(p-diethylaminophenyl)arsine 3,3'-bis 1,5-diphenyl-4,5-di(p-diethylaminophenyl)- methyl-di-(p-diethylaminophenyl)phosphine 2-pyrazoline phenyl-tri-(p-diethylaminophenyl)stannane 3,3'-bis(1,5-diphenyl-4,5-di(p-diethylaminophenyl)- methyl-tri-(p-diethylaminophenyl)stannane 2-pyrazoline 20 tetra-p-diethylaminophenylgermane. 3,3'-bis(1,5-diphenyl-4-(p-methoxyphenyl)-5-ethyl diphenyl-p-diethylaminophenylsilane . . 2-pyrazoline . . . : , p-diethylaminophenylarsine . . . . . ; : . . . 3,3'-bis(1,5-diphenyl-4-chloromethyl-2-pyrazoline) tetrakis-diphenyl-(p-diethylaminophenyl)plum 1,5-diphenyl-4,5-dimethyl-3-3'-(1'-p-tolyl-4'-dieth byl)methanes...... yl-5',5'-methylphenyl)-2'-pyrazolyl)-2-pyrazoline 25 tetrakis-diphenyl)p-diethylaminophenyl)stannyl)- 4-(p-diphenylaminophenyl)-3-buten-1-yne stannane ...... p-diphenylaminostyrene bisphenyl-(p-diethylaminophenyl) dibismuthine. ethyl-p-diphenylaminocinnamate tri-(p-diethylaminophenyl)phosphine sulfide methyl-p-diphenylaminocinnamate di(p-diethylaminophenyl)thioxotin p-diphenylaminocinnamoyl chloride . 30 4-(di-p-tolylamino)-2'-(di-p-tolylamino)styryl stil p-diphenylaminocinnamic acid, N,N-diphenylamide bene ...... p-diphenylaminocinnamic acid anhydride 4-(di-p-tolylamino)-2',4'-dimethyl-5-4-(di-p-: 3-(p-diphenylaminophenyl)-2-butenoic acid tolyl)styryllstilbene ...... bis(p-diphenylaminobenzal)succinic acid and combinations of the above. . 4-N,N-bis(p-bromophenyl)aminocinnamic acid 35 In preparing the coating composition useful results 1-(4-diphenylamino)naphthacrylic acid are obtained where the photoconductor substance is p-diphenylaminocinnamic acid present in an amount equal to at least about 1 weight p-diphenylaminocinnamonitrile percent of the coating composition. The upper limit in 7-diphenylamino coumarin , , the amount of photoconductor: substance present can p-diphenylaminophenylvinylacrylic acid 40 be widely varied in accordance with usual practice. In p-diphenylaminobenzyl-p'-diphenylaminocinnamate those cases where binder is employed, it is normally 7-(p-diphenylaminostyryl)coumarin is - required that the photoconductor substance be present p-diphenylaminocinnamyl alcohol in an amount from about 1 weight percent of the coat 4-diphenylaminocinnamaldehyde semicarbazone: . ing composition to about 99 weight percent of the O-p-diphenylaminocinnamoyl 45 coating composition. A preferred weight range for the p'-diphenylaminobenzaldehyde oxime photoconductor substance in the coating composition p-diphenylamino cinnamaldehyde oxime. is from about 10 weight percent to about 60 weight 1,3-bis(p-diphenylaminophenyl)-2-propen-1-ol percent. " ...... " M methyl-p-diphenylaminobenzoate W The amount of sensitizer that can be added to a N,N-diphenylanthranilic acid SO photoconductor-incorporating layer. to give effective 3-p-diphenylaminophenyl-1-1-propanol increases in speed can vary widely. The optimum con 4-acetyltriphenylamine semicarbazone ethyl-2,6- centration in any given case will vary with the specific diphenyl-4-(p-diphenylaminophenyl)benzoate photoconductor and sensitizing compound used. In 1-(p-diphenylaminophenyl)-1-hydroxy-3-butyne general, substantial speed gains can be obtained where 4-hydroxymethyltriphenylamine 55 an appropriate sensitizer is added in a concentration 1-(p-diphenylaminophenyl)ethanol range from about 0.0001 to about 30 percent by weight 4-hydroxytriphenylamine of the film-forming coating composition: Normally, a 2-hydroxytriphenylamine sensitizer is added to the coating composition in an 4-formyltriphenylamine oxime amount from about 0.005 to about 5:0 percent by 4-acetyltriphenylamine oxime 60 weight of the total coating composition...... 1-(p-diphenylaminophenyl)hexanol Various addenda that can be added to the photocon 1-(p-diphenylaminophenyl) dodecanol ductive compositions are plasticizers, coating aides p-diphenylaminobenzoic acid anhydride (leveling agents) and abrasion resistant materials such 4-cyanotriphenylamine . . as silicones, etc. . . . ; : ...... p-diphenylaminobenzoic acid, N,N-diphenylamide 65 Electrophotographic elements of the invention can p-diphenylaminobenzoic acid be prepared with any photoconductive compound and p-diphenylaminobenzoyl chloride. the sensitizers of this invention in the usual manner, 3-p-diphenylaminophenylpropionic acid i.e., by blending a dispersion or solution of the photo

a. 4,018,606 13 14 conductive compound together with a binder, when ency by a conventional exposure operation such as, for desirable, and coating or forming a self-supporting example, by contact-printing technique, or by lens layer with the photoconductive composition. Gener projection of an image, etc, to form a latent image in ally, a suitable amount of the sensitizing compound is 5 the photoconducting layer. By exposure of the surface mixed with the photoconductive coating composition in this manner, a charge pattern is created by virtue of so that, after thorough mixing, the sensitizing com the fact that light causes the charge to be conducted pound is uniformly distributed throughout the desired away in proportion to the intensity of the illumination layer of the coated element. in a particular area. The charge pattern remaining after Solvents of choice for preparing coating composi 10 exposure is then developed, i.e., rendered visible, by tions of the present invention can include a number of treatment with a medium comprising electrostatically solvents such as benzene, toluene, acetone, butanone, attractable particles having optical density. The devel chlorinated hydrocarbons, e.g., methylene chloride, oping electrostatically attractable particles can be in ethylene chloride, etc, ethers, e.g., tetrahydrofuran, or 15 the form of a dust e.g., powder, a pigment in a resinous mixtures of these solvents, etc. carrier, i.e., toner, or a liquid developer may be used in Coating thicknesses of the photoconductive compo which the developing particles are carried in an electri sition on a support can vary widely. Normally, coating cally insulating liquid carrier. Methods of development in the range of about 0.001 inch to about 0.01 inch 20 of this type are widely known and have been described before drying is useful for the practice of this invention. in the patent literature in such patents, for example, as The preferred range of coating thickness is found to be U.S. Pat. No. 2,297,691, and in Australian Pat. No. in the range from about 0.002 inch to about 0.006 inch 212,315. In processes of electrophotographic repro before drying although useful results can be obtained 25 duction such as in xerography, by selecting a develop outside this range. ing particle which has as one of its components, a low Suitable supporting materials for coating the photo melting resin it is possible to treat the developed photo conductive layers of the present invention can include conductive material with heat and cause the powder to any of a wide variety of electrically conducting sup adhere permanently to the surface of the photoconduc ports, for example, paper (at a relative humidity about 30 tive layer. The heating is generally carried out in a 20 percent); aluminum-paper laminates; metal foils temperature range of from about 25°C. to about 150 such as aluminum foil, zinc foil, etc; metal plates, such C. The preferred range is from about 100° C to about as aluminum, copper, zinc, brass, and galvanized 135° C. plates; vapor deposited metal layers such as silver, 35 The present invention is not limited to any particular nickel or aluminum on conventional film supports such mode of use of the new electrophotographic materials, as cellulose acetate, poly(ethylene terephthalate), pol and the exposure technique, the charging method, the ystyrene and the like conducting supports. An espe transfer (if any), the developing method, and the fixing cially useful conducting support can be prepared by 40 method as well as the material used in these methods coating a support material such as poly(ethylene tere can be selected and adapted to the requirements of any phthalate) with a layer containing a semiconductor particular technique. dispersed in a resin. Such conducting layers both with Electrophotographic materials according to the pre and without insulating barrier layers are described in 45 sent invention can be applied to reproduction tech U.S. Pat. No. 3,245,833. Likewise, suitable conducting niques wherein different kinds of radiation, i.e., elec coating can be prepared from the sodium salt of a car tromagnetic radiations as well as nuclear radiations can boxyester lactone of a maleic anhydridevinyl acetate be used. For this reason, it is pointed out herein that copolymer. Such kinds of conducting layers and meth although materials according to the invention are ods for their optimum preparation and use are disclosed 50 mainly intended for use in connection with methods in U.S. Pat. Nos. 3,007,901, 3,245,833 and 3,267,807. comprising an exposure, the term "electrophotogra The elements of the present invention can be em phy' wherever appearing in the description, and the ployed in any of the well known electrophotographic claims, is to be interpreted broadly and understood to processes which require photoconductive layers. One 55 comprise both xerography and xeroradiography. such process is the aforementioned xerographic pro The invention is further illustrated by the following cess. As explained previously, in a process of this type examples which include preferred embodiments the electrophotographic element is given a blanket thereof. electrostatic charge by placing the same under a co 60 rona discharge which serves to give uniform charge to EXAMPLE 1 the surface of the photoconductive layer. This charge is A formulation comprising a binder of poly(4,4'-iso retained by the layer owing to the substantial insulating propylidenebisphenoxyethyl-co-ethylene terephthal property of the layer. The electrostatic charge formed ate) (Vitel PE 101 manufactured by Goodyear Tire & on the surface of the photoconducting layer is then 65 Rubber Co.) and 20 percent by weight of 2,4,7-trinitro selectively dissipated from the surface of the layer by 9-fluorenone (TNF) photoconductor and 1 percent by exposure to light through an imagebearing transpar weight of Diane Blue pigment having the formula: 4,018, 606 15 16

O H N-C OH CHO OCH 3 HO

was coated at 0.004 inch wet thickness over a poly wherein M is a metal (ethylene terephthalate) film support which was coated In Examples 1-12 of the present application, Relative with a 0.4 ND conductive nickel layer. The pigment 15 H & D Electric Speeds are reported. The relative H & was milled in the composition in a shaker with steel D electrical speeds measure the speed of a given photo balls for a period of 4 hour to 4 hours. conductive material relative to other materials typically The above sensitized element was compared to 5 within the same test group of materials. The relative control elements containing the same components speed values are not absolute speed values. However, wherein control A contains no sensitizer, control B 20 relative speed values are related to absolute speed val contains 1 percent by weight of Indofast Yellow toner ues. The relative electrical speed (shoulder or toe having the formula: speed) is obtained simply by arbitrarily assigning a value, Ro, to one particular absolute shoulder or toe O speed of one particular photoconductive material. The 25 relative shoulder or toe speed, Rn, of any other photo conductive material, n, relative to this value, Ro, may then be calculated as follows: Rn = (An) (Ro/Ao) wherein An is the absolute electrical speed of material n, Ro is the speed value arbitrarily assigned to the first material, and Ao is the absolute electrical speed of the first material. The absolute H & D electrical speed, either the shoulder (SH) or toe speed, of a material may be determined as follows. The material is electro O statically charged under, for example, a corona source Control C contains 1 percent by weight of Selkirk Red 35 until the surface potential, as measured by an electrom pigment having the formula: eter probe, reaches some suitable initial value V, typi cally about 600 volts. The charged element is then SOG) OH COON, exposed to a 3000 K tumgsten light source through a stepped density gray scale. The exposure causes reduc (A, Cu “) 40 tion of the surface potential of the element under each CH NEN step of the gray scale from its initial potential V to some lower potential V the exact value of which de pends upon the amount of exposure in meter-candle seconds received by the area. The results of these mea surements are then plotted on a graph of surface poten tial V vs, log exposure for each step, thereby forming Control D contains 1 percent by weight Benzidine Yel an electrical characteristic curve. The electrical or low pigment having the formula: electrophotographic speed of the photoconductive

H. Cl C (H, CmOH C-OH H I H N-Ca-Cam-NEN NEN-C-C-N O O Control E contains 1 percent by weight Britione Red pigment having the formula: 60 OH G) MGE) composition can then be expressed in terms of the SO reciprocal of the exposure required to reduce the sur face potential of any fixed selected value. The actual positive or negative shoulder speed is the numerical 65 expression of 10 divided by the exposure in meter-can dle-seconds required to reduce the initial surface po tential V to some value equal to V minus 100. This is referred to as the 100 volt shoulder speed. Sometimes 4,018,606 17 18 it is desirable to determine the 50 volt shoulder speed and, in that instance, the exposure used is that required Table 3-continued Relative Electrical to reduce the surface potential to V minus 50. Simi H & D Speeds larly, the actual positive or negative toe speed is the Binder (sh/100 V Toe) numerical expression of 10 divided by the exposure in 5 carbonate (Lexan 145 meter-candle-seconds required to reduce the initial mfg. by General Electric Co.) 1 1513.3 54/6.3 potential V to an absolute value of 100 volts. Again, if Chlorinated polyethylene one wishes to determine the 50 volt toe speed, one (62.5% chlorine) 10.5/1.7 1415.0 merely uses the exposure required to reduce V to an Polystyrene 8,471.3 171.3 Poly(vinyl-n-bromo absolute value of 50 volts. An apparatus useful for 10 benzoate-vinyl determining the electrophotographic speeds of photo acetate) . . . 16.8/0.6 111 C.3 Poly(vinyl chloride conductive compositions is described in Robinson et vinylidene chloride) 28.4/3.8 231.6 al., U.S. Pat. No. 3,449,658 issued June 10, 1969. The Methyl methacrylate 52.6/1.1 180/1.0 relative speeds obtained for the various elements tested Poly(vinyl chloride are given in Table 1 below. 15 vinyl acetate) 1897 18.9 70/6.3 Table 1 assigned an arbitrary speed value of 100. Relative Electrical A max H & D Speed Example (nm) (sh/100 V Toe) 20 EXAMPLE 4 63S 100/3.2 * 100/3.3 Photoconductive elements comprising Diane Blue Control A am 2.0/O 4.2/O pigment and poly(N-vinyl-9-carbazole) and mono Control B 445 111.0 20.8/.3 Control C 570 201.6 30/1 bromo-poly(N-vinyl-9-carbazole) as photoconductors Control D 450 2011.2 24.2f1.6 have relative electrical H & D speeds as shown in Table Control E 565 1611.2 19.2f1.7 25 4. assigned an arbitrary speed value of 100. Table 4 % Diane Relative Electrical H & D The speed of the element containing Diane Blue Photoconductor Blue Speeds (sh/100 V toe) pigment was unexpectedly superior to that containing Poly(N-vinyl-9- no pigment and those containing other similar pig- 30 carbazole) * 100/1.8 * 100/3.8 Monobromo poly(N- rents. vinyl-9- carbazole) 17716.9 23916.4 EXAMPLE 2 Poly(N-vinyl-9- carbazole) 0.25 8.1/O 4.8/O A formulation comprising a binder of Vitel PE 101, 35 Monobromo poly(N- 20 percent by weight of 4,4'-diethylamino-2,2'-dime vinyl-9-carbazole 0.25 92.21.5 1147.7 thyltriphenylmethane photoconductor and varying amounts of Diane Blue pigment was coated at 4 ml. assigned an arbitrary speed value of 100. thickness of a poly(ethylene terephthalate) support which was coated with a 0.4 ND conductive nickel EXAMPLE 5 layer. The Relative H and D speeds of the elements are 40 shown in Table 2. A series of compositions containing Vitel PE101 binder, 20% by weight of various organic photoconduc Table 2 tors and 4% by weight of photoconductor and binder of Percent Relative Electrical H&D Speeds Diane Blue pigment in methylene chloride solvent was Pigment (sh/100 V Toe) 45 prepared. The compositions were coated onto conduc O.S * 100/<.5 * 100/2 tive supports and tested as in Example 1. Table 5 shows O 240/5 157.5/10 2.0 220/12.6 300/9 the relative electrical speeds obtained. 4.0 500/32 300/10 Table 5 "assigned an arbitrary speed value of 100. 50 R Electrical H & D Speeds Photoconductor (sh/100 V Toe) EXAMPLE 3 Triphenylamine 100/3.3 * 100/0 Tri-p-tolylamine 66.7/9.6 100/3 A series of composition containing 20% by weight of Bis(4-diethylamino)- tetraphenylmethane 10418.3 66.712.7 the photoconductor of Example 2, 4% by weight Diane 55 Phenyl-bis(4-diethylamino Blue pigment and various binders were coated as in phenylgermane) 16,718.3 91.772 Example 2. The relative electrical H & D speeds of these elements are shown in Table 3. "assigned an arbitrary speed value of 100. Table 3 W 60 Relative Electrica EXAMPLE 6 H & D Speeds Binder (sh/100 V Toe) A series of compositions containing Vitel 101 binder, Poly(4,4'-isopro 20% by weight of various photoconductors and in Ex pylidene bis ample 6, 4% Diane Blue pigment, in Control A, 0.8% phenoxyethyl-co- 65 2,6-bis(4-ethylphenyl)-4-(4-amyloxyphenyl)- ethylene terephthalate) (Vitel mfg. by Goodyear thiapyrylium perchlorate, and in Control B 0.8% Rho Tire & Rubber Co.) 100/7.4 * 100/3.2 damine B pigment were coated and evaluated as in Bisphenol A poly Example 1. The results are shown in Table 6. 4,018,606 19 20 Table 6 Relative Electrical H and D Speed (Shi 100 V Toe) Example 6 Control A Control B -- r -- -- d phenyl-bis-(2-methyl 4-diethylaminophenyl)- arsine 4500/158 1575/O * 0.018 80/0 55/O 180/0 triphenyl-2-methyl-4- diethylaminophenyl stanae 175010 125/O 32.519.8 25018.5 9070 90/O phenyl-tris-(4- 8 diethylaminophenyl)- - Sanae 2500/0 1000/0 400, 17.8 400, 15.8 128/O 58/O triphenyl-p-diethyl aminophenyl plumbane 56370 4000 163/O 14310 0/0 300 methyl-tri-(p-diethyl aminophenyl)silane 3000/55 125/20 400/22.5 400/20 *assigned an arbitrary speed value of 100 with all other listed values relative thereto.

EXAMPLE 7 A series of compositions containing Vitel PE-101 20 binder, 20% by weight of various photoconductor com- Table 7-continued positions and in Example 7, 1% by weight of Pigment Photoconductor Relative Electrical & D Violet RB having the formula: Combination Example Speeds (Sh/100 V Toe) 2,2'-dimethyltri NO, 25 phenylmethane w 10% TNF-- 0% 7 1538161.5 650/2.5 . O 4,4'-diethylamino H 2,2'-dimethyltri HO C-N phenylmethane O 30 *assigned an arbitrary speed value of 100. H CH-N-C NEN

IOC OCH A series of compositionsEXAMPLES containing 8-9 Vitel PE 101 is binder, 20% by weight of phenyl-tris(4-diethylamino phenylgermane) photoconductor and in Control A no pigment sensitizer, in Control B, 4% of Pigment red R of this invention, in Control A no sensitizer and in having the formula Control B 1% by weight of Pigment Red having the ; : : a formula 40 Cls O CH . . CH H 3. HO C-a-N: O H CH HO C-N 45 N=N

NO, 50 in Examples 8, 4% by weight of Malta Red X-2284 pigment having the formula was prepared and coated as in Example 1. The results are shown inas Table 7. 55 O, m H Table 7 O CN Photoconductor Relative Electrical H & D O Combination Example Speeds (Sh/100 V Toe) H 10% TNF -- 10% Control A * 10016.5 * 100/40 60 NC NN triphenylamine 10% TNF - 10% triphenylamine Control B 10817.7 80/4.0 10% TNF -- 0% triphenylamine 7 615134.6 400/6 OCH 10% TNF-- 10% Control. A 814.8 4012.5 3 4,4'-diethylamino- 65 2,2'-dimethyltri Fish Control B 92/5.5 5512.5 and in Example 9, 4% by weight of Pigment Violet RB 4,4'-diethylamino- having the formula 4,018,606 21 22 -continued NO Pigment C O O ll H Il H OH C-N-CH HO C-N 5 O H ll NE CH-N-C NEN 10 NO, OCH,

Pigment D NO The compositions were coated as in Example 1. The is O results are shown in Table 8. Il H HO C-N Table 8 --no-um-m-m-m-m-m-m-m-m- O Relative Electrical H & D H ll Example Speeds (Sh/100 V Toe) CH-N-C NEN Control A * 100/0 * 100/0 20 Control B 3088/73.5 1127/35 8 18529/941 10000/225 OCH 9 35294/1323 28169/380 3. "assigned an arbitrary speed value of 100. 25 igment E EXAMPLES 10-12 it h A series of compositions containing Vitel PE 101 HO C-N binder, 20% by weight of various photoconducts and O 4%The by compositions weight of various were coatedmilled pigmentsand tested was as prepared.in Exam- 30 ()-- EN ( ) ple 1. The results are shown in Table 9. Table 9 Relative Electrical H & DS SE100 V Toe OCH Example Pigment' - Photoconductor A Photoconductor B Photoconductor C Control A A ** 100/0 90/O 500/0 300/9 63/0 100/0 Control B B 0/0 0/0 O/O 6.3/0 6.3/0 8/O 10 C 2310 3510 30/0 13.8/O 13.8/O 35/O 11 D 900/25 700/11.3 6250/175 3500/113 5000/175 6250/300 12 E -- - 2500/200 1900/68 - - **assigned an arbitrary speed value of 100 with all other listed speeds relative thereto. *Formulas for pigments can be found on the following pages. Photoconductor A - triphenylamine Photoconductor B - 4,4'-bis-diethylamino-2,2'-dimethyltriphenylmethane Photoconductor C-2,4,7-trinitrofluorenone

Pigment A CH O 50 CH HO C-N It is seen that low speeds were obtained using Control A and Control B as the sensitizer while high speeds NN were obtained using Examples 11 and 12 as the sensi 55 tizers. Although the actual recorded speeds of the com position containing Example 10 as the sensitizer were NO, not high, the composition of Example 10 was a paste containing an unknown surfactant which desensitized the composition and the sensitizer was not completely 60 dispersed in the composition. Pigmentgnei B O The invention has been described in detail with par OH R-ch, ticular reference to certain preferred embodiments thereof, but it will be understood that variations and CH(CH) NEN modifications can be effected within the spirit and 65 scope of the invention...... HOS3. SOH3 We1. A claim: photoconductive compositiono comprising a pho Na toconductor and a sensitizing amount of a sensitizer for 4,018,606 23 24 the photoconductor comprising an organic pigment having the formula SONa HO COONa R gh 5 C n R2 NEN-meC X C

O wherein X consists of the atoms necessary to complete 5. A photoconductive composition comprising a pho toconductor and a sensitizing amount of a sensitizer for a naphthalene, anthracene, or the photoconductor comprising an organic pigment OH 15 having the formula C / NO O H -?y O OCH HQ C-N 5-N 20 R NEN ring; R", R, and R are independently selected from the ON group consisting of hydrogen, halogen, alkoxy, NO, 25 alkyl, SOH or alkali metal salts thereof, and COOH or alkali metal salts thereof; 6. The photoconductive composition of claim 1 O wherein the photoconductor is an organic photocon Il H Il H 30 ductor. , -C-N NO, and -C-N 7. The photoconductive composition of claim 6 wherein the photoconductor is selected from the group and wherein R and R can comprise the atoms neces consisting of arylamines, arylalkanes, organometallics sary to complete a phenyl, naphthyl or anthryl ring; and 35 and polymeric photoconductors, 8. The photoconductive composition of claim 1 R is selected from the group consisting of wherein the photoconductor is an inorganic photocon ductor. O O H Il H 9. The photoconductive composition of claim 8 wherein the inorganic photoconductor is selected from 8-N-O-No, 2--O). or COOM wherein M is the group consisting of selenium, zinc oxide, titanium oxide, cadmium sulfide, cadmium selenide and lead or COOM oxide. wherein M is alkyl or an alkali or alkaline earth metal. 10. An electrophotographic element comprising a 2. The photoconductive composition of claim 1 con conductive support having coated thereon a photocon taining an electrically insulating polymeric binder. 45 ductive composition comprising a photoconductor and 3. A photoconductive composition comprising a pho a sensitizing amount of a sensitizer for the photocon toconductor and a sensitizing amount of a sensitizer for ductor comprising an organic pigment having the for the photoconductor comprising an organic pigment mula having the formula

NO O HO Il H O C-N H Il N-C TO.NEN

4. A photoconductive composition comprising a pho- 65 toconductor and a sensitizing amount of a sensitizer for the photoconductor comprising an organic pigment having the formula 4,018,606 25

R gh CN 2 V R2 NEN-C X HC N 1 C R3 R wherein X consists of the atoms necessary to complete 10 a naphthalene, anthracene, or \. 14. The electrophotographic element of claim 10 OH wherein the organic pigment has the formula C 15 NO, 1 O -c.1 Yn H Yc OCH HO C-N R 20 ring; ' R", R, and R are independently selected from the group consisting of hydrogen, halogen, alkoxy, NO2, ON (O) alkyl, SOH or alkali metal salts thereof, and COOH or alkali metal salts thereof; 25 15. the electrophotographic element of claim 10 O o wherein the photoconductor is an organic photocon Il H H ductor, p ---O-No, and arc-N 16. The electrophotographic element of claim 15 30 wherein the organic photoconductor is selected from the group consisting of arylamines, arylalkanes, or and wherein R and R can comprise the atoms neces ganometallics and polymeric photoconductors. sary to complete a phenyl, naphthyl or anthryl ring; and 17. The electrophotographic element of claim 10 R is selected from the group consisting of wherein the photoconductor is an inorganic photocon 35 ductor. O O H H 18. The electrophotographic element of claim 10 C-N NO, 2--O). or COOM wherein M is wherein the inorganic photoconductor is selected from the group consisting of selenium, zinc oxide, titanium oxide, cadmium sulfide, cadmium selenide and lead or COOM 40 oxide. wherein M is alkyl or an alkali alkaline earth metal. 19. In an electrophotographic process wherein an 11. The electrophotographic element of claim 10 electrostatic charge pattern is formed on an electro wherein the photoconductor is dispersed in an electri photographic element the improvement characterized cally insulating polymeric binder. - in that said electrophotographic element has a photo 12. The electrophotographic element of claim 10 45 conductive layer comprising a photoconductor and a wherein the organic pigment has the formula sensitizing amount of a sensitizer for the photoconduc

NO, Ho 9 H O H ll NarC NEN O-CH

65 13. The electrophotograhic element of claim 10 tor comprising an organic pigment having the formula wherein the organic pigment has the formula 4,018,606 27 28

O O R ph H H 2 CN 2-R-O-No, --O). or COOM wherein M is R2 NSN-C 5 N G'S R or COOM wherein M is alkyl or an alkali or alkaline R3 earth metal. 20. The electrophotographic process of claim 19 wherein the photoconductor is dispersed in an electri wherein X consists of the atoms necessary to complete 10 cally insulating polymeric binder. a naphthalene, anthracene, or 21. The electrophotographic process of claim 19 wherein the organic pigment has the formula

O H NPC

22. The electrophotographic process of claim 19 wherein the organic pigment has the formula

HO .- h -a N O 35 R 23. The electrophotographic process of claim 19 40 wherein the organic pigment has the formula . , , ring; ...... R, R, and R are independently selected from the group. consisting of hydrogen, halogen, alkoxy, NO, alkyl, SOH or alkali metal salts thereof; and COOH or alkali metal salts thereof; 45

O O il H H , -C-N NO, and -C-N 50 and wherein R and R can comprise the atoms neces sary to complete a phenyl, naphthyl or anthryl ring; and R is selected from the group consisting of 55

60

65