US3615414A

US3615414A - Photoconductive compositions and elements and method of preparation

Info

Publication number: US3615414A
Application number: US804266A
Authority: US
Inventors: William A Light
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1969-03-04
Filing date: 1969-03-04
Publication date: 1971-10-26
Anticipated expiration: 1988-10-26
Also published as: DK133208B; GB1301542A; SE351057B; CH511463A; ES377107A1; DK133208C; BE746328A; FR2037392A5; NL7003114A

Abstract

Multiphase heterogeneous compositions are formed from an organic dye and electrically insulating polymeric material. A solution of dye and polymer is prepared and subsequently treated, for example, by exposure of a coating thereof to a solvent to form the heterogeneous compositions. These compositions which are useful as photoconductors or electrophotosensitizers are characterized by a radiation absorption maximum that is substantially shifted from the absorption maximum of the dye dissolved in the polymer to form a homogeneous composition. Particularly useful dyes are the pyrylium dyes.

Description

United States Patent William A. Light Rochester, N.Y.

Mar. 4, 1969 Oct. 26, 197 1 Eastman Kodak Company Rochester, N.Y.

Continuation-impart of application Ser. No. 586,820, Oct. 14, 1966, now abandoned Continuation-impart of application Ser. No. 674,005, Oct. 9, 1967, now abandoned.

Inventor Appl. No. Filed Patented Assignee PHOTOCONDUCTIVE COMPOSITIONS AND ELEMENTS AND METHOD OF PREPARATION 26 Claims, No Drawings 11.8. C1 ..96/l.6, 96/1 R, 252/501, 260/37 PC, 260/345.1, 260/327 B, 106/307 Int. Cl G03g 7/00,

{50] Field oiSearch 96/1 6,1, 1.2, 1.5, l.8;252/.501;260/40, 345.1, 327; 106/307 [56] References Cited UNITED STATES PATENTS 3,250,615 5/1966 Van Allan et a1. 96]] 3,397,086 8/1968 Bartfai 117/218 Primary Examiner-George F. Lesmes Assistant Examiner-M. B. Wittenberg Atrorneys-W. H. J. Kline, .l. R. Frederick and T. Hiatt ABSTRACT: Multiphase heterogeneous compositions are formed from an organic dye and electrically insulating polymeric material. A solution of dye and polymer is prepared and subsequently treated, for example, by exposure of a coating thereof to a solvent to form the heterogeneous compositions. These compositions which are useful as photoconductors or electrophotosensitizers are characterized by a radiation absorption maximum that is substantially shifted from the absorption maximum of the dye dissolved in the polymer to form a homogeneous composition. Particularly useful dyes are the pyrylium dyes.

PHOTOCUNDUCTIVE COMPOSITIONS AND ELEMENTS AND METHOD 01F PREPARATION This application is a continuation-in-part of U.S. applications Ser. No. 586,820, filed Oct. 14, 1966, now abandoned and Ser. No. 674,005, filed Oct. 9, 1967.

This invention relates to electrography and to photoconductive compositions, elements and structures useful in electrography and particularly in electrophotography. ln addition, this invention relates to providing novel electrophotographic compositions together with methods for their preparation and use.

Electrophotographic imaging processes and techniques have been extensively described in both the patent and other literature, for example, U.S. Pat. Nos. 2,221,776; 2,277,013; 2,297,691; 2,357,809; 2,551,582; 2,825,814; 2,833,648; 3,220,324; 3,220,831; 3,220,833 and many others. Generally, these processes have in common the steps of employing a nor mally insulating photoconductive element which is prepared to respond to imagewise exposure with electromagnetic radiation by forming a latent electrostatic charge image. A variety of subsequent operations, now well known in the art, can then be employed to produce a permanent record of the image.

One type of photoconductive insulating structure or element particularly useful in electrophotography utilizes a composition containing a photoconductive insulating material dispersed in a resinous material. A unitary electrophotographic element is generally produced in a multilayer type of structure by coating a layer of the photoconductive composition onto a film support previously overcoated with a layer of conducting material or the photoconductive composition may be coated directly onto a conducting support of metal or other suitable conducting material. Such photoconductive compositions have shown improved speed and/or spectral response, as well as other desired electrophotographic characteristics when one or more photosensitizing materials or addenda are incorporated into the photoconductive composition. Typical addenda of this latter type are disclosed in U.S. Pat. Nos. 3,250,615, 3,141,770 and 2,987,395. Generally, photosensitizing addenda for photoconductive compositions are incorporated to effect a change in the sensitivity or speed of a particular photoconductor system and/or a change in its spectral response characteristics. Such addenda can enhance the sensitivity of an element to radiation at a particular wavelength or to a broad range of wavelengths where desired. The mechanism of such sensitization is presently not fully understood. The phenomenon, however, is extremely useful. The importance of such effects is evidenced by the extensive search currently conducted by workers in the art for compositions and compounds which are capable of photosensitizing photoconductive compositions in the manner described.

Usually the desirability of a change in electrophotographic properties is dictated by the end use contemplated for the photoconductive element. For example, in document copying applications the spectral electrophotographic response of the photoconductor should be capable or reproducing the wide range of colors which are normally encountered in such use. If the response of the photoconductor falls short of these design criteria, it is highly desirable if the spectral response of the composition can be altered by the addition of photosensitizing addenda to the composition. Likewise, various applications specifically require other characteristics such as the ability of the element to accept a high surface potential, and exhibit a low dark decay of electrical charge. 1t is also desirable for the photoconductive element to exhibit high shoulder speed and high toe speed as measured in an electrical H and D or characteristic curve, a low residual potential after exposure, and resistance to fatigue. H and D curves as referred to herein are analogous to the curves first employed by Hurter and Driffield except that voltage or charge on the electrophotographic element is used instead of density. Sensitization of many photoconductive compositions by the addition of certain dyes selected from the large number of dyes presently known has hitherto been widely used to provide for the desired flexibility in the design of photoconductive elements in particular photoconductor-containing systems. At the present time,

however, no photosensitizer addenda to photoconductor compositions or elements have been shown to the art which are capable of producing a significant improvement in substantially all of the aforementioned desirable characteristics. Conventional dye addenda to photoconductor compositions have generally shown only a limited capability for overall improvement in the totality of electrophotographic properties which cooperate to produce a useful electrophotographic element or structure. The art is still searching for improvements in shoulder and toe speeds, rapid recovery and useful electrophotographic speed from either positive or negative electrostatic charging. Thus far, dye sensitization alone has not produced the quality of improvement in photoconductor-containing systems which might be considered satisfactory for the wide variety of electrophotographic applications presently contemplated by workers in the art.

It is, therefore, an object of this invention to provide the art of electrophotography with novel compositions of matter, methods for their preparation and elements for their optimum employment.

It is a further object of this invention to substantially remove the limitations encountered heretofore by novel means using photosensitizing addenda for organic photoconductive materials in the field ofelectrophotography. For example, it is an object of this invention to provide photoconductive compositions and elements having greater speed than has previously been obtainable with conventional organic photoconductive compounds or compositions.

It is also an object of this invention to provide novel photoconductive compositions and elements prepared therefrom which show substantially improved resistance to fatigue and which demonstrate substantially increased speed of recovery between charging and exposure cycles.

It is likewise an object of this invention to provide novel photoconductive elements having the aforementioned characteristics which are well suited for use with either positive or negative initial charging potentials thereby permitting a wide latitude in the selection and use of image-toning means and compositions as well as providing a greater degree of freedom in the selection ofthe type of image to be reproduced than has previously been possible.

It is still a further object of this invention to provide novel photoconductive elements containing zinc oxide and having enhanced electrophotographic properties.

The above and further objects and advantages of this invention will become apparent from the following description of the invention.

It has been discovered that many useful photographic sensitizing dyes and mixtures of such dyes, can be combined with electrically insulating polymers in solution and treated as described herein to form a separately identifiable multiphase heterogeneous composition. These heterogeneous compositions can be formed as described herein. The feature composition thus formed has been found to be useful as either a photoconductor or as a sensitizer in electrophotographic compositions containing other photoconductors.

A solution containing the constituents of the feature electrophotographic compositions can be coated in the form of a layer in a conventional manner onto a suitable support and the formation ofthe composition of the invention achieved in situ in the formed layer. One technique for converting a homogeneous coating of dye and polymer to the present heterogeneous system is by prolonged contact of the coating to vapors of solvent which is capable of being absorbed in or penetrating the layers, the dye being caused to migrate and form aggregates in a multiphase system. Usually such vapor exposure is effective to permit formation of a substantial amount of the feature compositions from the dye and polymer in about two minutes at about 70 F. Likewise, inhibition of solvent removal in an otherwise normal coating operation ofa dope solution made up of the dye and polymer can form the feature compositions. Similarly, immersing the homogeneous coating in a solvent, or coating from an original solvent mixture which contains a high boiling solvent which persists in the coating during drying, are among other methods of forming the feature compositions. Another suitable technique for forming the present heterogeneous compositions involves high speed shearing ofa solution of dye and polymer in accordance with the procedure described in copending Gramza application Ser. No. 674,006, filed Oct. 9, 1967, now abandoned.

Observable heterogeneous structure in the present photoconductive layers is indicative of the presence of the feature compositions. The presence of such compositions in the layer permits the layer to produce the hereinafter enumerated improved properties when used as a photoconductor or as a photosensitizing addendum for other photoconductors. The feature compositions when formed in situ in the layer generally have an identifiable heterogeneous appearance when viewed under at least 2500X magnification, although such compositions may appear to be substantially optically clear to the naked eye in the absence of magnification. In other compositions of the invention there is a macroscopic heterogeneity. Suitably, the dye-containing aggregate in the discontinuous phase in predominantly in the size range of about 0.01 to 25 microns. However, it should be noted that when the heterogeneous compositions of the invention are used to sensitize a particulate photoconductor, such as zinc oxide, another discontinuous phase will be present which may not fall within this size range.

in general, the present heterogeneous compositions are two phase organic solids containing dye and polymer. The polymer forms an amorphous matrix or continuous phase which contains a discrete discontinuous phase as distinguished from a solution. The discontinuous phase contains a significant portion of the dye present and generally a predominant portion of the dye present is in the discontinuous phase. The dye in the discontinuous phase can be considered as being in particulate form; however, that phase need not be comprised wholly of dye. It is believed that in some instances the discontinuous phase may be comprised ofa cocrystalline complex of dye and polymer. However, it is also believed that all of the aggregates which can be formed in accordance with this invention are not necessarily comprised of both dye and polymer. Preferably, substantially all of the dye present in the system is in the discontinuous phase. When the present compositions are used in conjunction with an organic photoconductor, the resultant photoconductive composition generally contains only two phases as the photoconductor usually forms a solid solution with the continuous polymer phase. On the other hand, when the present multiphase compositions are used in conjunction with a particulate photoconductor, three phases may be present. In such a case, there would be a continuous polymer phase, a discontinuous phase containing dye as discussed above and another discontinuous phase comprised of the particulate photoconductor. Of course, the present multiphase compositions may also contain additional discontinuous phases.

The feature compositions of this invention have shown many useful properties in the electrophotographic art. Electrophotographic elements made with layers containing this new substance alone or together with other photoconductive compounds and compositions are broadly improved. The feature compositions of this invention can be specifically identified by their effect as a photoconductive material per se or upon other photoconductive materials as sensitizers therefor. A particularly distinctive property characteristic of electrophotographic elements having coated thereon many of the compositions of the invention is an increased photosensitivity irrespective of the polarity of surface charge placed on the photoconductive element. Such photoconductive elements exhibit high photosensitivity and photoconductivity as well as good regeneration. The observed tendency of elements containing the material of this invention to recover very rapidly after charging and exposure is important in continuous or cyclic electrophotographic applications. When a feature composition of the invention is present in an electrophotographic element, the element has an improved ability to repeatedly accept a high surface potential after completion of a charge-expose-develop cycle. Such elements can, therefore, be further characterized by their resistance to the kind of electrical fatigue which is normally characteristic ofphotoconductor-containing elements and which prevents rapid reuse of such elements.

The prior art photoconductive layers can be prepared in a wide variety of ways. Typically, a solution comprising a photoconductor, a film-forming hydrophobic binder and a sensitizing dye can be prepared as shown in U.S. Pat. No. 3,141,770 and cast or coated in the manner taught therein, for example, in the form of a layer onto a suitably prepared conducting support material. A layer prepared in this manner absorbs radiation over a particular wavelength region charac teristic of the dye used and appears substantially homogeneous under 2500X magnification. The electrophotographic properties of these prior art photoconductive layers are adequate for the preparation of a useful image when charged, exposed imagewise and developed in the conventional manner. However, according to this invention, a significant improvement in many of the electrophotographic properties presently characteristic of these types of materials, particularly a speed increase, is provided by the formation of the feature nonhomogeneous multiphase compositions of this invention. The wavelength of the radiation absorption maximum characteristic of the heterogeneous compositions is substantially shifted from the wavelength of the radiation absorption maximum of the substantially homogeneous untreated dyepolymer solid solution. The new absorption maximum characteristic of the aggregates of this invention is not necessarily an overall maximum for the system as this will depend upon the relative amount of dye in the aggregate. Such an absorption maximum shift in the formation of the present multiphase heterogeneous systems is generally of the magnitude of at least about 10 mp" If mixtures of dyes are used, one dye may cause an absorption maximum shift to a longer wavelength and another dye cause an absorption maximum shift to a shorter wavelength. In such cases the formation of the present heterogeneous compositions can be more easily identified by viewing under magnification. To prepare such an improved element a photoconductive layer prepared as described above can be exposed to the vapor of an organic solvent. For example, after about two minutes at room temperature or about 70 F. this treatment produces changes in the layer. The color of the layer during treatment changes, e.g. from a deep blue to a shade of red, and absorbs radiation in a wavelength region different than the original material. When the photoconductive layer is removed from the solvent vapor and viewed under magnification, the layer containing the feature composition has a two phase heterogeneous appearance.

A photoconductive layer of the invention transformed as above, in addition to having undergone physical appearance changes, has also undergone a conversion which imparts to the layer the novel properties described herein such as an increased electrophotographic speed, sometimes regardless of the polarity of the original electrostatic charge. Sometimes the dark conductivity of such transformed material is also lowered, and the layer can be repeatedly charged and exposed with no apparent electrical fatigue. Likewise, such feature photoconductive layers do not have a memory or retain spurious images when subsequently charged and exposed. The present photoconductive material can be rapidly charged and its charge stability is high when subjected to high humidity or repeated exposure and development.

Particularly useful dyes in the present invention are pyrylium dyes, including pyrylium, thiapyrylium and selenapyrylium dye salts, which are capable of forming sensitizing and photoconductive compositions of this invention can be represented by the following general formula:

wherein R", R,,, R, R", and R" can each represent (a) a hydrogen atom; (b) an alkyl group typically having from 1 to carbon atoms, such as methyl, ethyl, propyl, isopropyl butyl, tertiary butyl, amyl, isoamyl, hexyl, octyl, nonyl, dodecyl, etc, (0) alkoxy groups like methoxy, ethoxy, propoxy, butoxy, amyloxy, hexoxy, octoxy, and the like; and (d) aryl groups including substituted aryl groups such as phenyl, 4-diphenyl, a1-

kylphenyls as 4-ethylphenyl, 4-propylphenyl, and the like, 211- koxyphenyls as 4-ethoxyphenyl, 4-methoxyphenyl, 4-amyloxyphenyl, 2-hexoxypheny1, Z-methoxyphenyl, 3,4-dimethox-,

yphenyl, and the like, B-hydroxy alkoxyphenyls as Z-hydroxyethoxyphenyl, 3-hydroxyethoxyphenyl, and the like, 4-

hydroxyphenyl, halophenyls as 2,4-dichlorophenyl, 3,4- dibromophenyl, 4-chlorophenyl, 2,4-dichlorophenyl, and the like, azidophenyl, nitrophenyl, aminophenyls as 4- diethylaminophenyl, 4-dimethylaminophenyl and the like, napthyl; and vinyl substituted aryl groups such as styryl, methoxystyryl, diethoxystyryl, dimethylaminostyryl, l-butyl- 4-p-dimethylaminophenyll ,3-butadienyl, ,B-ethyl-4- dimethylaminostyryl, and the like; and where X is a sulfur, oxygen or selenium atom, and Zis an anionic function, including such anions as perchlorate, fluoroborate iodide, chloride, bromide, sulfate, periodate, p toluenesulfonate, and the like. In

addition, the pair R" and R as well as the pair R" and R" cantogether be the necessary atoms to be complete an aryl ring fused to the pyrylium nucleus.

Typical pyrylium dyes for use in the present invention are listed in table 1.

TABLE 1 Compound Number Name of Compound l2 MM-dimethylaminophenyl)-2-(4-ethoxyphenyl)-6- phcnylthiapyrylium perchlorate l3 4-(4-dimethylaminophenyl)-2 (4-rnethoxyphenyl)-6- (Lmethylphenyl)pyrylium perchlorate l4 4-(4-diphenylaminophenyl)-2,6-

diphenylthiapyrylium perchlorate l5 2,4,64riphenylpyrylium perchlorate perchlorate l7 4-( 2,4-dichlorophenyl)-2,6-diphenylpyrylium perchlorate l8 4-( 3,4-dichlurophenyl)-2,6diphenylpyrylium perchlorate l9 2,6-bis(4-methoxyphenyl)-4-phcnylpyrylium perchlorate 20 6(4-methoxyphenyl )2.4-diphenylpyrylium perchlorate 21 2-(3,4-dichlorophenyll-4-(4-methoxyphenyly6- phenylpyrylium perchlorate 22 4-(4-amyloxyphenyl)-2,6-bis(4'ethylphenyl )pyrylium perchlorate methoxyphenyhpyrylium perchlorate Z4 2,4,6-triphenylpyrylium fluoroborate Ill 2,6-bis(4-ethylphenyl)-4-(4- methoxyphenyl)pyrylium perchlorate 2.6'bis(4-ethylphenyl)-4-(4- methoxyphenyhpyrylium fluoroborate 6-(3.4diethoxystyryl)-2.4-diphenylpyrylium perchlorate 6-(3,4-dicthoxy-fi-amylstyryl)-2,4-diphenylpyrylium fluoroborate 6-(4-climethylamino-B-ethylstyryl)-Z 4- diphenylpyrylium fluorohorate 6-( l-n-amyl-4-p-dimethylaminophenyl 1,3

butadienyl)2.4-diphenylpyrylium fluoroborate 6-(4-dimethylaminostyryl)-2,4-diphenylpyrylium fluoroborate 6-(or-ethyl-flfi-dimethyleminopheniyl vinylene)-2.4-

diphenylpyrylium fluoroborate 6-( l-butyl-4-p-dimethylaminophenyl-l,3-

butadienyl)-2,4-diphenylpyryliurn fluoroborate 6-(4-dimethylaminostyryl)-2.4-diphenylpyryliurr\ perchlorate 6-[fi.fl-bis(4 -dimethylaminophenyI|)vinylene]-2.4-

diphenylpyrylium perchlorate 2,6-bis(4-dimethylaminostyryl)--phenylpyrylium perchlorate 6-(fimethyl-4-dimethylaminostyryl)-2.4-

diphenylpyrylium fluoroborate 64 l ethyl-4-p-dimethylaminophenyl-l ,J-butadienyl- 2,4 diphenylpyrylium fluoroborate 6-[fi,fl-bis(4-dimethylaminophenylJvinylene]-2.4-

diphenylpyrylium fluoroborate 6-( l-methyl-4p-dirnethylaminophenyl-l ,3-

butaclienyl)-2,4-diphenylpyrylium fluoroborate 4-(4-dimethylarninophenyl)-2,6-diphenylpyrylium perchlorate 2,6bis(4-ethylphenyl)-4- henylpyrylium perchlorate 2 6-bis(4-ethylphenyl)4-methoxyphenylthiapyryliurn fluoroboratc 2.4,6-triphenylthiapyrylium perchlorate 4-(4-methoxyphenyl)-2.fi-diphenylthiapyrylium erchlorate 6(4-methox vphenylr2,d-diphenylthiapyrylium perchlorate 2,6bis(4-methoxyphenyl)-4-phenylthiapyrylium perchlorate 4-(2,4-dichlorophenyl)-2,6-diphenylthiapyrylium perchlorate 2,4,6-tris(4-methoxyphenyl)thiapyrylium perchlorate 2,6-bis(4-ethylphenyl)-4-phenylthiapyrylium perchlorate 4-(4-amyloxyphenyl)-2.6-bis(4- ethylphenyhthiapyrylium perchlorate 6-t4-dimethylaminostyryl) Z,4-diph-enylthiapyrylium perchlorate 2.4,fi-triphcnylthiapyrylium l'luoroborate 2,4.6'triphenylthiapyrylium sulfate 4-( 4-methoxyphenyl b-Z,6-diphcnylthiapyrylium l'luorohorate 2.4 6 triphenylth|apyrylium chloride 2 -(4-amyloxyphenyl)-4.G-diphenylthiapyrylium fluoroborate 4-(4-amyloxyphcr|yl)-Z,6-his(4 methoxyphenyl)thiapyrylium perchlorate 2.6-bis(4-ethylphenyli444- methoxyphenyl)thiapyrylium perchlorate 4-anisyl 2,6-bis(4-n-amyloxyphenylltthiapyrylium chloride 2 [B,fl-bis(4-dimethylaminophenyl)winylene]4,6-

diphenylthiapyrylium perchlorate 6-(dethylA-dirnerhylaminostyryl)-2.4- di henylthiapyrylium perchlorate 2-(3,4.4]iethoxystyryl)-4,6-diphenylthiapyrylium perchlorate Z,4,6-trianisylthiapyrylium perchlorate 2,6-bist4-ethylphenyl)-4-(4- methoxyphenyl)thiapyrylium chloride 6[B,,B-bis(4-dimcthylaminophenyl)vinylene]-2 4- bis(4-ethylphenyl)pyrylium perchlorate Z 6-bis(4-amyloxyphenyl)-4(4- methoxyphenyl)thiapyrylium perchlorate 2 (4ethylpheny|)-4.6-diphenylthia yrylium perchlorate 2,6'diphenyl-4-(4-methoxyphenyl )thiapyrylium perchlorate 2,6-diphenyl-4-(4-methoxyphenyl)thiapyrylium fluoroborate 2,6-bis(4ethylphenyl-4-(4-namyloxyphenyl)thiapyrylium perchlorate 2,6-bis(4-methoxyphenyl) 4-(4-namyloxyphenyl)thia yrylium perchlorate 76 2.4.6-tris(4-methoxyphenyl)thiapyrylium fluoroboratc 77 2 4-diphenyl-6-(3 4-diethoxystyryl)pyrylium perchlorate 78 4-(-dimethylaminophenyU-Z- phenylbenzotb)selenapyrylium perchlorate 79 2-(2,4-dimethoxyphenyl)-4-(4- dimerhylamino henyl)-benzo(b)selenapyrylium perchlorate 80 4 (4-dimcthylaminophenyl)-2,6-

diphenylselenapyrylium perchlorate 8l 4-(4-dimcthylaminophenyl)-2-(4-ethoxyphenyl)-6- phenylselenapyrylium perchlorate 82 4-[4-bis(2-chloroethyl)aminophenyl1-2.6-

diphenylselenapyrylium perchlorate 83 4-(4-dimethylaminophenyl)-2,6-bis(4-ethylphenyl)- selenapyrylium perchlorate 84 4-(4-dimethylamino-2-methylphenyl)-2,6- X5 diphenylselenapyrylium perchlorate 8S 3-(4-dimethylaminophenyl)naphtho(2.l-

b)selenapyrylium perchlorate 86 4-(4-dimethylaminosryryl)-2-(4- methoxyphenyl)benzo(b)selenapyrylium perchlorate 87 2.6-di(4-diethylaminophenyl)-4- phenylselenapyrylium perchlorate 88 4-(4-dimethylaminophcnyl)-2-(4-ethoxyphenyl)-6- phenylthiapyrylium fluoroborate Preferred pyrylium dyes used informing the feature aggregates are pyrylium dye salts having the formula:

Iii-K R I Z- a wherein:

R and R can each be phenyl radicals, including substituted phenyl radicals having at least one substituent chosen from alkyl radicals of from I to 6 carbon atoms and alkoxy radicals having from 1 to 6 carbon atoms;

R can be an alkylamino-substituted phenyl radical having from 1 to 6 carbon atoms in the alkyl moiety including dialkylamino-substituted and halogenated alkylamino-substituted phenyl radicals;

X can be an oxygen or a sulfur atom; and Z is the same above.

While the pyrylium dyes are preferred in preparing the present two-phase heterogeneous systems, other photographic spectral sensitizing dyes that activate light exposed areas of photographic compositions can be utilized in the electrically insulating polymer of the present system, such as the J-aggregated dyes disclosed in copending Gilman and Heseltine U.S application Ser. No. 804,267, cofiled herewith and entitled PHOTOCONDUCTIVE COMPOSITIONS AND ELE- MENTS, including .I-aggregates of cyanine, merocyanine and 5 styryl dyes such as anhydro-Lethyll '-sulfobutyl-2,2'-cyanine hydroxide,

2-( 5 ,5 -dicyano-2,4-pentenylidene )-3-ethyl- 380 to about 1,000 my.

Electrically insulating filmforming polymers suitable for the formation of clectrophotographic compositions containing the feature aggregates of this invention include polycarbonates and polythiocarbonates, polyvinyl ethers, polyesters, polya-olefins, phenolic resins, and the like Mixtures of such polymers can also be utilized. Such polymers include those which function in the formation of the aggregates of this invention as well as functioning as binders for the sensitizer and photoconductor. Typical polymeric materials from these classes are set out in table 2.

TABLE 2 Number Polymeric Materials l polystyrene 2 polyvinyltoluene 3 polyvinylanisole 4 polychlorostyrene 5 polya-methylstyrene 6 polyacenaphthalene 7 poly(vinyl isobutyl ether) 8 poly(vinyl cinnamatc) 9 poly(vinyl benzoate) l0 poly(vinyl naphthoate) l l polyvinyl carbazole l2 poly(vinylene carbonate) l3 polyvinyl pyridine l4 poly(vinyl acetal) l5 poly(vinyl butyral) l6 poly(ethyl methacrylate) l7 poly(butyl methacrylate) l8 poly(styrene-co-butadienc) l9 poly(styrene-co-methyl methacrylate) 20 poly(styrene-co-ethyl ucrylatc) 2| poly(styrene-co-acrylonitrile) 22 poly(vinyl chloride-co-vinyl acetate) 23 poly(vinylidene chloride-co-vinyl acetate) 24 poly(4,4-isopropylidenediphenyl-co-4,4'-

isopropylidenedicyclohexyl carbonate 25 poly[4,4'-isopropylidendbi$(2.6

dibrOmophenyUCarbonate] 26 poly(4,4'-isopropylidenebis(2.6-dichlorophenyl)- carbonate] 27 poly[4,4'-isopropylidenebis(2.6-

dimethylphenyl)carbonate] 28 poly(4,4'-isopropylidenediphenyl-co-1.4-

cyclohexyldimethyl carbonate) 29 poly(4 4'-isopropylidenediphenyl terephthalatc-coisophthalatc) 30 poly(3,3'-ethylenedioxyphenyl thiocarbonate) 3l poly[4.4'-isopropylidenediphenyl carbonate-coterephthalatc) 32 poly(4,4'-isopropylidenediphenyl carbonate) 33 poly(4,4'-isopropylidenediphenyl thiocarbonate) l4 poly(2,2-butancbis-4-phenyl carbonate) 3S poly(4 4'-is0propylidcnediphenyl carbonate-block ethylene oxide) 36 poly(4,4'-isopropylidenediphenyl carbonate-block tetramethyleneoxide) 37 poly[4,4'-isopropylidcnebis(2- methylphenyUcarbonale] 38 poly(4.4-isopropyliclenediphenyl-co-l .4-phcnylene carbonate) 39 poly(4.4'-isopro ylidcnediphenyl-co-l.3-phenylcne carbonat 40 poly(4,4-isopropylidenediphenyl-co-4.4'-diphenyl carbonate 4] poly(4.4'-isopropylidenediphenyl-co-4.4'-

oxydiphcnyl carbonate) 42 poly(4.4'-isopropylidenediphenyl-co-4Acarbonyl diphenyl carbonate) 43 poly(4 4'-isopropylidencdiphcnyl-co-4.4

elhylcnediphenyl carbonate) 44 poly[4,4-methylene bis(Z-methylphenyl)carbonate] 45 poly[ l ,l-(p-bromophenylethane)bis(4- phenyl)carbonate] 46 poly[ 4,4 isopropylidenediphenyl-cmsull'onyl bis(4- phenyl)carbonate] 47 poly[ l ,l-cyclohexane bis(4-phenyl)carbonate] 48 poly(4,4'-isopropylidenediphenoxydimethylsilane) 49 poly[4.4'-isopropylidene bis(2-chlorophenyl carbonate] S0 poly[a.a.u'.a-tetramethyl-p-xlcne his(4-phenyl carbonate)] 5] poly(hexnfluoroisopropylidenedi-d-phenyl carbonate) 52 poly(dichlorotetrafluoroisopropylidenedi-l-phenyl carbonate) 53 poly(4 4-isopropylidenediphenyl 4,4-

isopropylidcne-dibenzoate) 54 poly(4.4'-isopropylidcnedibenzyl 4.4

isopropylidene-dibenzoate) 55 poly(4.4'-isopropylidencdi-l-naphthyl carbonate) $6 poly[4.4-isopropylidene bis(phenoxy-4-phenyl sulfonateH 57 acetophenone formaldehyde resin 58 poly[4,4-isopropylidene bis(phenoxyethyl)-coethylene terephthalate] S9 phenol-formaldehyde resin 60 polyvinyl acetophenone 6i chlorinated polypropylene 62 chlorinated polyethylene 63 poly(2,6-dimethylphenylene oxide) 64 poly(ncopentyl-2,6-naphthalenedicarboxylate) 65 poly(ethylene terephlhalate-co-isophthalate) 66 poly( l,4-phenylene-co'1,3-phenylene succinate) 67 poly(4,4'-isopropylidenediphenyl phenylphosphonate) 68 polylm-phenylcarboxylate) 69 poly( l ,4-cyclohexanedimethyl terephthalate-co' isophthalate) 70 poly(tetramethylene succinate) 71 poly(phenolphthalein carbonate) 72 poly(4-chloro- 1,3-phenylene carbonate) 73 poly(2-methyl-l ,3-phenylene carbonate) 74 poly( l,l-bi-2-naphthyl thiocarbonate) 75 poly(diphenylmethane bis-4 phenyl carbonate) 76 poly[2,2-(3-methylbutanc)bis-4-phenyl carbonate] 77 poly[2,2-l3,3-dimethylbutane)bis-4-phenyl carbonate] 78 poly l,l-|1-(l-naphtliylethylidene)lbis 4-phenyl carbonate 79 poly[2,2-(4-methylpentane)bis-4-phenyl carbonate] 80 poly[4,4'-(2-norbornylidcne)diphenyl carbonate] poly[4,4'-(hcxahydro-4,7-methanoindan-5- lidene)diphenyl carbonate] Especially useful polymers for forming the present heterogeneous compositions are compounds number 28, 30-47, 49, 51, 53, 54 and 76-8l as listed in table 2 above.

Included among the preferred polymers used for preparing the two-phase heterogeneous compositions of the invention, including copolymers, are those linear polymers having the following recurring unit:

wherein:

R and R when taken separately, can each be a hydrogen atom, an alkyl radical such as methyl, ethyl, propyl, isopropyl, butyl, tertiary butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and the like including substituted alkyl radicals such as trifluoromethyl, etc. and an aryl radical such as phenyl and naphthyl including substituted aryl radicals having such substituents as a halogen, alkyl radicals of from 1 to 5 carbon atoms, etc.; and R, and R when taken together, can represent the carbon atoms necessary to form a cyclic hydrocarbon radical including cycloalkanes such as hexyl and polycycloalkanes such as norbornyl, the total number of carbon atoms in R and R being up to 19;

R and R, can each be hydrogen, an alkyl radical of from 1 to 5 carbon atoms or a halogen such as chloro, bromo, iodo, etc, and

R is a divalent radical selected from the following:

Among the hydrophobic carbonate polymers particularly useful in accordance with this invention are polymers comprised of the following recurring unit:

wherein:

each R is a phenylene radical including halo substituted phenylene radicals and alkyl substituted phenylene radicals; and R, and R are described above. Such compositions are disclosed, for example, in US, Pat. Nos, 3,028,365 and 3,317,466. Preferably polycarbonates containing an alky- .lidene diarylene moiety in the recurring unit such as those prepared with Bisphenol A and including polymeric products of ester exchange between diphenylcarbonate and 2,2-bis(4- hydroxyphenyl)-propane are used in the practice of this invention Such compositions are disclosed in the following US. Pat Nos. 2,999,750; 3,038,874; 3,038,879; 3,038,880; 3,106,544; 3,106,545; 3,106,546; and published Australian Pat. Specification No. 195 75/56. A wide range of film-forming polycarbonate resins are useful, particularly completely satisfactory results are obtained when using commercial polymeric materials which are characterized by an inherent viscosity of about 0.5 to 0.6. In addition, a high molecular weight material such as a high molecular weight Bisphenol A polycarbonate can be very useful. Preferably, such high molecular weight materials have an inherent viscosity of greater than about 1 as measured in 1,2-dichloroethane at a concentration of 0.25 g./ ml. and a temperature of about 25 C. The use of high molecular weight polycarbonate, for example, facilitates the formation of aggregate compositions having a higher dye concentration which results in increased speeds.

Liquids useful for treating polymer-dye coatings to form the aggregate or heterogeneous compositions of the invention can include water, and a number of organic solvents such as aromatic hydrocarbons, for example, benzene and toluene, ketones such as acetone and ethylmethyl ketone, halogenated hydrocarbons such as methylene chloride and alcohols like methyl, ethyl, and benzyl alcohol, as well as mixtures of such solvents.

The present heterogeneous compositions are electrically insulating in the dark such that they will retain in the dark an electrostatic charge applied to the surface thereof. in addition, as mentioned above, the present compositions are also photoconductive. This term has reference to the ability of such compositions to lose a retained surface charge in proportion to the intensity of incident actinic radiation. in general, the term photoconductive" as used to describe the present heterogeneous compositions means that the amount of incident radiation energy in meter-candle-seconds required to cause a l00-vo1t reduction in retained surface potential is not greater than about 200 meter-candle-seconds.

The heterogeneous compositions of this invention are typically coated as a photoconductor or as a sensitizer onto a conventional conducting support such as paper (at a relative humidity above '20 percent) including paper made more conductive by various coating and/or sizing techniques or carrying a conducting layer such as a conducting metal foil, a layer con taining a semiconductor dispersed in a resin, a conducting layer containing the sodium salt of a carboxyester lactone of maleic anhydride and a vinyl acetate polymer such as disclosed in US. Pat. Nos. 3,007,901 and 3,262,806, a thin film of vacuum deposited nickel, aluminum, silver, chromium, etc., a conducting layer as described in U.S, Pat. No. 3,245,833, such as cuprous iodide, and like kinds of conducting materials. Such conducting materials can be coated in any well known manner such as doctor-blade coating, swirling, dip-coating, spraying, and the like. Other supports, including such photographic film bases as poly(ethylene terephthalate), polystyrene, polycarbonate, cellulose acetate, etc., bearing the above conducting layers can also be used. The conducting layer can be overcoated with a thin layer of insulating material selected for its adhesive and electrical properties before application of a photoconducting layer. Where desired, however, the photoconducting layer can be coated directly on the conducting layer where conditions permit to produce the unusual benefits described herein.

When the present multiphase compositions of the invention are used as photoconductive compositions, useful results are obtained by using the described dyes in amounts of from about one to about 50 percent by weight of the coating composition.

When the present multiphase compositions are used as sensitizers for photoconductive coatings, useful results are obtained by using the described dyes in amounts of about 0.001

to about 30 percent by weight of the photoconductive coating composition, although the amount used can be widely varied. The upper limit in the amount of photoconductive composition present in a sensitized layer is determined as a matter of individual choice and the total amount of any photoconductor used will vary widely depending on the material selected, the electrophotographic response desired, the proposed structure of the photoconductive element and the mechanical properties described in the element. Lesser amounts of the present feature compositions can be utilized as sensitizing amounts to increase the speed sensitivity of other photoconductors than amounts that would be used if the feature material were the only photoconductor present.

Coating thicknesses of a photoconductive composition containing the feature material of the invention can vary widely. More generally, a wet coating in the range from about 0.005 inch to about 0.05 inch on a suitable support material is used in the practice of the invention. The preferred range of wet coating thickness was found to be in the range from about 0.002 inch to about 0.030 inch.

The present invention can readily be used for enhancing the sensitivity and extending the spectral range of sensitivity of a variety of organic photoconductors and inorganic photoconductors including both nand P-type photoconductors. For example, the present invention can be used in connection with organic, including organometallic, photoconducting materials which have little or substantially no persistence of photoconductivity. Representative organometallic compounds are the organic derivatives of Group Illa, [V0, and Va metals such as those having at least one amino-aryl group attached to the metal atom. Exemplary organometallic compounds are the triphenyl-p-dialkylaminophenyl derivatives of silicon, germanium, tin and lead, the tri-p-dialkylaminophenyl derivatives of arsenic, antimony, phosphorus, bismuth boron, aluminum, gallium, thallium and indium. Useful photoconductors of this type are described in copending Goldman and Johnsom U.S. Pat. application Ser. No. 650,664, filed July 3, 1967 and Johnsom application Ser.No. 755,711, filed Aug. 27, 1968.

An especially useful class of organic photoconductors is referred to herein as organic amine photoconductors. Such organic photoconductors have as a common structural feature at least one amino group. Useful organic photoconductors which can be spectrally sensitized in accordance with this invention include, therefore, arylamine compounds comprising (1) diarylamines such as diphenylamine, dinaphthylamine, N,N-diphenylbenzidine, N-phenyl-l-naphthylamine,N-phenyl-2-napthylamine,N,N'-diphenyl-p-phenylenediamine, 2-carboxy-5-chloro-4'-methoxydiphenylamine, p-anilinophenol, N,N'-di-2-naphthyl-p-phenylenediamine, those described in Fox U.S. Pat. 3,240,597, issued Mar. 15, 1966, and the like, and (2) triarylamines including (a) nonpolymeric triarylamines, such as triphenylamine, N,N,N'-N'-tetraphenylm-phenylenediamine, 4-acetyltriphenylamine, 4-hexanoyltriphenylamine, 4-lauroyltriphenylamine, 4-hexyltriphenylamine, 4-dodecyltriphenylamine, 4,4-bis(diphenylamino)benzil, 4,4-bis(diphenylamino)benzophenone and the like, and (b) polymeric triarylamines such as poly[N,4"] polysebacyltriphenylamine, polydecamethylenetriphenylamine, polyN-(4-vinylphenyl)diphenylamine, polyN-(vinylphenyl)- a, a-dinaphthylamine and the like. Other useful amine'type photoconductors are disclosed in U.S. Pat. No. 3,180,730, issued Apr.27, 1965.

Useful photoconductive substances capable of being sensitized in accordance with this invention are disclosed in Fox U.S. Pat. No. 3,265,496, issued Aug. 9, 1966, and include those represented by the following general formula:

wherein T represents a mononuclear or polynuclear divalent aromatic radical, either fused or linear (e.g., phenyl, naphthyl, biphenyl, binaphthyl, etc.), or a substituted divalent aromatic radical of these types wherein said substituent can comprise a member such as an acyl group having from 1 to about 6 carbon atoms (e.g., acetyl, 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, ethoxy, propoxy, pentoxy, etc.), or a nitro group; M 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 1 to about 6 carbon atoms (e.g., acetyl, 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.), or a nitro group; O can represent a hydrogen atom, a halogen atom or an aromatic amino group, such as MNI-I-; b represents an integer from 1 to about 12; and, R 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, an alkoxy group, an acyl group, or a nitro group, or a poly(4-vinylphenyl) group which is bonded to the nitrogen atom by a carbon atom of the phenyl group.

Polyarylalkane photoconductors are particularly useful in producing the present invention. Such photoconductors are described in U.S. Pat. No. 3,274,000, French Pat, No. 1,383,461 and in copending application of Seus and Goldman titled PHOTOCONDUCTIVE ELEMENTS CONTAINING ORGANIC PHOTOCONDUCTORS, Ser. No. 627,857, filed Apr. 3, 1967, now U.S. Pat. No. 3,542,544. These photoconductors include leuco bases of diaryl or triaryl methane dye salts, l,l,l-triarylalkanes wherein the alkane moiety has at least two carbon atoms and tetraarylmethanes, there being substituted an amine group on at least one of the aryl groups attached to the alkane and methane moieties of the latter two classes of photoconductors which are nonleuco base materials.

Preferred polyarylalkane represented by the formula:

photoconductors can be wherein each of D, E and G is an aryl group and .l 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 are preferably phenyl groups, although naphthyl groups can also be used. Such aryl groups can contain such substituents as alkyl and alkoxy typically having 1 to 8 carbon atoms, hydroxy, halogen, etc., in the ortho, meta orpara positions, orthosubstituted 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 L can be an alkyl group typically having 1 to 8 carbon atoms, a hydrogen atom, an aryl group, or together the necessary atoms to form a heterocyclic amino group typically having 5 to 6 atoms in the ring such as morpholino, pyridyl, pyrryl, etc. At least one of D, E, and G is preferably p-dialkylaminophenyl group. When .1 is an alkyl group, such an alkyl group more generally has 1 to 7 carbon atoms.

Representative useful polyarylalkane photoconductors ln- E4 clude the compounds listed in table 3.

Inventor US. Patent No. TABLE3 Hoegl et al. 3.037. Sues et al. 3,041.]65 Schlesinger 3,066,023 Compound Bethe 3.072.479 Number Name of Compound Klupfel et al. 3,047,095 N eta]. 3,ll2,l97 Cassiers et al. 3. l 33,022 I 4,4-benzylidene-bis(N,N-diethyl-m-toluidine) Schlesinger 3M4633 2 4',4"-diaminoA-dimethylaminoQ'.2"- Noe a! a1 3 I 22435 dimethyltriphenylmethane sues a a1 3J27'266 3 4',4"-bis(diethylamino)-2.6dichloro-2,2" scmesinger 31303146 dimethyltriphenylmethane 5 Cassie 3 13| 060 4 4.4"- is-(diethylamino)-2'.2"' Schlesinger 3l3933g dimethyldiphenylnaphthylmethane Schlesinger 3.1395539 5 2'.2"-climethyl-4,4',4"-tris(dimethylamino- Cassius 3.140346 )triphenylmethane Davis at al. 3J4 l .770 6 4',4"-bis(diethylarnino)-4-dimethylamino-2',2"- g 3J48'932 dimethyltriphenylmethane 2O Cassiers 3.l55.503 7 4',4"-bis(diethylamino)-2-chloro2'.2"-dimethyl-4- Cassius 7 dimethylaminotriphenylmethane Tomanek 3,l6l.505 8 4,4--bis(diethylamino l 4-dimethylamino-2,2',2"- Schlesinger 3J63530 trimethyltriphenylmethane S hl i 3, l 63,53l 9 4',4''-bis(dimethylamino-2-chlori:J-2'.2'' Schlesinger 3.1 3.53 dimethyltriphcnylmethane 2 H l 3,|69,06() l0 4 ',4"bis(dimethylamino)-2',2"-dimethyl 4- 5 smmpf 3 I 74854 methoxytriphenylmethane Klupfel et al. 3.l80.729 ll bis(4-diethylamino)-l,IJ-triphenylethane Kl f l 8 3|, 3 |80 730 l2 bis(4-diethylamino)tetraphenylmethane Nwgebauer 3339347 13 4',4" -bis(bcnzylethylamino)-2'.2"- Neugebauer 3.20 .3 6 dimethyltriphenylmcthane F 3,240,597 l4 4'. "-bis(d y am Schlesinger 3,257.202

diethoxytriphenylmelhane S er 1, 3 357 203 l5 4,4-bis(dimethylamin0)-l .l .l-triphenylethane s cl 3,257,203 l6 l-(4 N.N-dimethylaminophcnyh-l,l-diphenylcthane p 3261496 I? 4-dimethylaminotetraphenylmethane K h 3361497 l8 4-diethylaminctetraphenylmethane N e I, 3,274.000

The composition of the present invention can be employed in photoconductive elements useful in any of the well known Another class of photoconductors useful in this invention elcctrophotographic processes which require photoconducare the 4-diarylamino-substituted chalcones. Typical comtive layers. One such process 18 the xerographlc process. In a pounds of this type are low molecular weight nonpolymeric process of this type, an electrophotographlc element held in ketones having the general formula: the dark is given a blanket electrostatic charge by placing it i under a corona discharge to give a uniform charge to the sur- 0 face of the photoconductive layer. This charge is retained by 3 L the layer owing to the substantial dark insulating property of the la er, i.e., the low conductivit of the la er in the dark. R, Y y y The electrostatic charge formed on the surface of the photoconductive layer is then selectively dissipated from the wherein R, and R are each phenyl radicals including subsurface of the layer by imagewise exposure to light by means stituted phenyl radicals and particularly when R is a phenyl ofa conventional exposure operation such as, for example, by radical having the formula: a contact-printing technique, or by lens projection of an image, and the like, to thereby form a latent electrostatic R image in the photoconductive layer. Exposing the surface in 3 5 this manner forms a pattern of electrostatic charge by virtue of the fact that light energy striking the photoconductor causes 3, the electrostatic charge in the light struck areas to be conducted away from the surface in proportion to the intensity of where R and R are each aryl radicals, aliphatic residues of l the illumination in a particular area. to 12 carbon atoms such as alkyl radicals preferably having l Th rge pa ern produced by exposure is then developed to 4 carbon atoms or hydrogen. Particularly advantageous or transferred to another surface and developed there, i.e., results are obtained when R, isa phenyl radical including subei h r the charged r h rg areas r n r i i y stituted phenyl radicals and where R is a diphenylaminophentreatment with a medium comprising electrostatically responyl, dimethylaminophenyl or phenyl. sive toner particles. The developing electrostatically respon- Other photoconductors which can be used with the present sive particles can be in various forms such as small particles of aggregate compositions include rhodamine B, malachite p g Or in the fvrm Of Small particles c pri ed of a green, crystal violet, phenosafranine, cadmium sulfide, cadmicolorant in a resinous binder. A preferred method of applying um selenide, parachloronil, benzil, trinitrofluoroenone, such dry toners to a latent electrostatic image for solid area tetranitrofluoroenone,etc. development is by the use of a magnetic brush. Methods of Thg f ll i table 4 comprises a i l li i f U, s, forming and using a magnetic brush toner applicator are Patents disclosing a wide variety or organic photoconductive described the following [Palcompounds and compositions which can be improved with 2,7 2,874,063; 2,984,163; respect to speed, sensitivity, and/or regeneration when incorand Reissue 2 ,77 Liquid developporated into the feature compositions and elements of this inmerit of the latent electroslauc Image can also be usedn vention liquid development the developing particles are carried to the image-bearing surface in an electrically insulating liquid carrier. Methods of development of this type are widely known and have been described in the patent literature, for example, U.S. Pat No. 2,907,674 and in Australian Pat. No. 212,315.

In dry developing processes, the most widely used method of obtaining a permanent record is achieved by selecting a developing particle which has as one of its components a lowmelting 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 1 photoconductive layer. In other cases, a transfer of the electrostatic charge image formed on the photoconductive layer can be made to a second support such as paper which could then become the final print after development and fusing. 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. Pat. Nos. 2,297,691 and 2,551,582 and in RCA Review Vol. 15 (1954) Pg. 469-484.

Processes such as described hereinbefore have found utility where the photoconductive layer is either inexpensive and expendable such as the various processes using photoconductive zinc oxide, or where the photoconductive media is rapidly reusable such as vitreous selenium. The feature compositions of this invention now permit a large number of known organic photoconductive compounds and compositions as well as inorganic materials to be employed in xerographic processes where rapid repeated charging and exposing are desired. For example, it is now possible with the advance provided by the discovery of the compositions of this invention to employ a closed loop or belt of reusable organic photoconductive film in a xerographic process thereby permitting extremely rapid reproduction of original images. In addition, photoconductive compositions containing the feature material can, of course, be in the form of coated plates and drums. With the discovery disclosed herein, it is now possible to reproduce copy from a microfilm or other original as rapidly as the state of the related mechanical handling arts will permit.

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

Example 1 Coatings of the invention are prepared by dissolving 6 g. poly(4,4'-isopropylidenediphenyl carbonate) resin (a composition formed from the reaction between phosgene and a dihydroxydiarylalkane or from the ester exchange between diphenylcarbonate and 2,2-hydroxphenylpropane, such as Lexan I" polycarbonate resin, General Electric Company); 4 g. of 4,4'-benzylidenebis(N,N-diethyl-m-toluidine) photoconductor; and 0.2 g. of 4-[4-bis(2- chloroethyl)a minophenyl]2,o-diphenylthiapyrylium perchlorate sensitizer in a solvent mixture consisting of 85 g. of dichloromethane and 5 g. of methanol by stirring the solids in the solvent for 2 hours at about 70 F; to form a solution. The resulting solution is hand coated at .004-inch wet coating thickness onto two separate strips of poly(ethylene terephthalate) film support overcoated with a conducting layer containing the sodium salt of a carboxyester lactone of maleic anhydride and vinyl acetate polymer such as disclosed in U.S. Pat. No. 3,007,901. The coating block is maintained at F. during coating. Both coatings are allowed to dry, and only one of the coatings is taped to a glass plate. This plate is immediately inverted over a bath of dichloromethane with the coating in the vapors thereof and kept there in room light at 70 F. for about two minutes. During this vapor treatment, an observable change takes takes place in the color and general physical appearance of the coating. The vapor-treated coating and the coating which was not vapor treated are examined microscopically at SOOX magnification. The vapor-treated coating has acquired a granular appearance not present in the nonvapor-treated coating. A spectrophotometric transmission curve for the vapor-treated coating indicates that the coating absorbed percent of the incident radiation at a principal absorption peak of 515 mg. The coating which has not been vapor treated absorbs 89 percent at an absorption peak of 555 mp. It is noted that the absorption peak of the vapor-treated coating has shifted to a shorter wavelength by 40 mpfrom the 555 mp. peak characteristic of the coating which has not been vapor treated. The actual positive electrical speeds of the converted (vapor-treated) and unconverted (nonvapor-treated) coatings are determined in the following manner. The element is electrostatically charged under a corona source until the surface potential, as measured by an electrometer probe, reaches about 600 volts. The charged element is then exposed to a 3,000 K. tungsten light source through a transparent continuous neutral density or gray scale wedge. The exposure causes reduction of the surface potential of the element under the neutral density wedge 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 these measurements are then plotted on a graph of surface potential V vs. log exposure for each step. The actual positive speed of the element can then be expressed in terms of the reciprocal of the exposure required to reduce the surface potential to any arbitrarily selected value. Herein, unless otherwise stated, the actual positive speed is the numerical expression of 10 divided by the exposure in meter-candle-seconds required to reduce the 600-volt charged surface potential to a value of 100 volts. Measuring as described herein, it is found that the coating which is vapor treated has a speed of 240 when initially charged positively. The coating which is not vapor treated has a speed of 63 when initially charged positively and a speed of 35 when initially charged negatively. The speeds and spectral characteristics of the coatings described hereinbefore, and similar coatings containing dyes other than 4-[4-bis(2-chloroethyl)aminophenyl1- 2,6-diphenylthiapyrylium perchlorate are tabulated in table 5. All of the converted or heterogeneous coatings can be toned to produce visible images after being charged and image-wise exposed, typical suitable toners being disclosed in U.S. Reissue Pat. No. 25,136.

TABLE 5 Converted Unconverted coating heterogeneous coating hmax. 7 Percent )tmax. Percent Dye (mu) absorption Speed (my) absorption Speed 4-(4-bis (2-ch1oroethyl)-aminophenyl)-2 fi-diphenylthiapyrylium perchlorate (Cmpd. No. 1, Table i). 5 89 i 55 515 I5 i 55, 4(4-dirnetl1ylaminophenyl)-2,6-diphenylthiapyrylium fiuoroborate (Cmpd. N0. 3,'Iable1) 585 1 5 mm x 2 5 4-(4-dimetliylamino-l-methylphenyl)-2,6-dipheny1pyry1ium perchlorate (Cmpd. 4, Table 1).. U 538 so{ 6 452 42{ 4-(4-dimethylaminopheny1)-2,fi-diphenylthiapyrylium p-toluenesulfonate (Cmpd. 1, Table 1). 570 71 fig 1 680 82 jgg 4-(4-dimethylaininopltenyl)-2-(4-mcthoxyphenyl)-6-phenylthiapyry1ium perchloy rate (Cmpd. 11, Table 1) 565 67 i 3; 675 65 't gg 4-(4-dimethylanlinopltenyl)-2-(4-ethoxyphenyl)-6-pl1enylthiapyrylium perclilorate (Cmpd. 12, Table 1) 570 71 Q 5 use 153 3 2 4(4-di1nethy1amhiophenyl)-2,ediphenylthiapyrylium perchlorate (Ompd. 2, Ta b 580 75 j 085 75 j g 1 Minus too slow to measure.

Example 2 The procedure for this example for preparing the photoconductive coatings is generally the same as described in example 1 with the following changes: The sensitizer, 4[4-bis(2- chloroethyl)aminopl1enyl]2,6-diphenylthiapyrylium perchlorate, is replaced with the same amount of 4-(4- dimethylaminophenyl)-2,o-diphenylthiapyrylium perchlorate (compound No. 2, table 1). Two solutions are prepared, one in 90 g. ofdichloromethane solvent, the other in a solvent mixture consisting of 85 g. of dichloromethane and 5 g. of methanol. Both solutions are stirred and coated as in example 1. Upon drying the coating prepared with dichloromethane as the sole solvent is converted into a two phase heterogeneous material by exposing to the vapors of dichloromethane solvent TABLE 8 The absorption shift of the two individual dyes contained in the mixtures of the first and third coatings have in effect combined to give a net absorption peak which is unchanged; however, the absorption spectrum has changed.

5 Example 4 Converted" llet trogvncous Unconverted coating coating Polymer abs ofgiz it iii Speed x]: Speed Poly[4,4-isopropy1idene dibenzyl 4,4-isopropy1idene dibenzoate] 585 an i *(530 as l ggd Poly(4,4-isopropylidenediphenyl 4,4-isopropylidene dibenzoate) 580 87 i 375 s *Heterogeneous coating formed by vapor treatment over tetrahydrofuran.

as in example 1. A predominant portion of the dye present is Example 5 in the particulate discontinuous phase. The coating from the 85 g. dichloromethane, 5 g. methanol solution is not so treated. In addition to the foregoing speed and spectral response changes, another sample of the first converted coating shown below is coated on an element having a nickel conducting layer and is repeatedly charged to a 600 v. potential and photodischarged to determine the resistance of the coat ing to electrical fatigue. After 1,000 such cycles at a time interval of 3 seconds between photodischarge and recharging, the coating will accept a 550 v. potential under the same charging conditions The uncoverted coating in the same system will accept only a 400 v. to 450 v. potential. Further cycling produces little change in the ability of the converted coating to accept a high surface potential while the unconverted coating continues to deteriorate. The speeds and spectral characteristics for compositions prepared as described above containing the same sensitizer binder combination with variations in the organic photoconductor used are tabulated in table 6.

TABLE 6 An electrophotographic element is prepared by dissolving 9.5 g. of the arylalkane polycarbonate described in example I and 0.5 g. of 4-(4-dimethylaminophenyl)-2,6-diphenylthiapyrylium fluoroborate sensitizer dye in g. of chloromethane solvent by stirring the solids in the solvent for 2 hours at about 70 F. A second solution is prepared by dissolving 9.5 g. of the polycarbonate and 0.5 g. of 4-(4-dimethylaminophenyl)-2.6- diphenylthiapyrylium fluoroborate in a solvent mixture consisting of 66.5 g. dichloromethane and 3.5 g. of methanol by stirring the solids in the solvent for 2 hours at about 70 F The first and second solutions are then separately hand coated at 0.005-inch wet coating onto a barrier or insulator overcoated conducting layer of cuprous iodide coated on a poly(ethylene terephthalate) film base. (Conducting layers with or without insulating overcoated barrier layers of the type used herein are shown in U.S. Pat. No. 3,245,833). The coating block is main tained at 90 F when solutions 1 and 2. are coated. After dry- 45 ing, the first coating is treated with solvent vapor as in example l and each of the coatings is examined microscopically at Unconverted coating Converted heterogeneous coating max Percent max. P r t Photooonduotot i flbsflrptlon peed u) absorption Speed 4,4'-benzylldenebis(N,N-diethyl-m-toluidine)... 580 i 56 685 75 wil w 1,3,6-tripheny12-pyrazoline 595 9a 1 680 81 @586 3; r p y e H 510 86 t 79 Example 3 500X magnification. It is noted that the coating from the first Photoconductive compositions and elements are prepared by the procedures of example 1. with the following changes: the sensitizer, 4-[4-bis(2-chloroethyl)aminophenyl]-2,6- diphenylthiapyrylium perchlorate, is replaced by the same amount of a mixture of sensitizer dyes in each case. The

solution has a granular appearance not present in the second coating. In addition, at least a predominant portion of the dye present in the first coating is contained in the granular appear ing discontinuous phase The spectrophotometric transmis sion curve for the first coating indicates that the coating ab sorbs 93 percent of the incident radiation ,at an absorption speeds and spectral characteristics for compositions contain- 65 ing sensitizer mixtures are tabulated in table 7 peak of 640 mp.. The second coating absorbs 94 percent at a TABLE 7 Converted Uneonverted coating heterogeneous coating Max. Percent Max. Percent Dye mixture (m absorption Speed (m absorption Speed 87.5 by weight Cmpd. 1, Table 1.... +35; +1, 600; 12.5%, by weight Ompd. 2, Table 1 565 88 i -20 565 81 i 1,6oo by Weight Ompd. 1, Table 1 550 82 +32; 510 65 t +1, 400, 15% by weigfit gmpg. T%llalell $4250 I ,2%%0 7 byweig t m a e 1 1072 Cmpd. 7, Tab 0 1.. 85 i -28 6 i -250 peak of 580 mp" It is noted that the absorption peak of the first coating has shifted to a longer wavelength by 60 mp, from the 580 my which is characteristic of the second coating. The speeds of these coatings are measured using the procedure described for example l. However, in this case, the 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) as measured with an electrometer probe. It is found that the first coating has a speed of 630 when initially charged positively, and 1,200 when initially charged negatively. The second coating has low speed when initially charged positively or negatively. The

speeds and spectral characteristics of coatings madein this same manner, and which contain dyes other than 4-(4- Example 6 The procedure of example 1 is generally repeated using as the sensitizer 0.4 g. of 4-(4-dimethylaminophenyl)-2,6- diphenylthiapyrylium perchlorate in place of the 4-[4,-bis(2- chloroethyl)-aminophenyl]-2,6-diphenylthiapyrylium perchlorate. The polycarbonate resin, the photoconductor and the sensitizer are dissolved in a solvent mixture of 52.5 g. of dichloromethane and b'52.5 g. of l,2-dichloroethane by stirring the solids in the solvent for 2 hours at about 70 F. The resulting dope is then coated onto a conducting substrate and converted into a two phase composition in the manner shown in example 1. The substrate consists of an evaporated nickel film coated on a poly(ethylene terephthalate) film base which is subbed with a terpolymer of 2 weight percent itaconic acid, 13 weight percent methyl acrylate and 85 weight percent vinylidene chloride. The net density of the evaporated nickel film is about 0.10 and resistivity of the substrate is about ohms/sq. This photoconductive coating has an absorption peak at 675 mu and absorbs 94 percent of the incident radiation at this wavelength. The positive and negative 3 second, 1,000 cycle regeneration of the coating (measured as described in example 2) is excellent and the positive and negative speeds measured as in example 1 are 3,200 and 3,500, respectively. The densities and resistivities of other metal conducting substrates as well as the speeds and absorption of other organic photoconductive coatings which are coated directly on these metal substrates are tabulated in table l0. The photoconducting layers show excellent regeneration pro- Example 7 The procedure of example I is repeated using as the dye 2,6-bis-(4-ethylphenyl)4-(4-dimethylaminophenyl)thiapyrylium perchlorate (Compound 10, table 1). After hand coating the resulting solution, an overcoat of toluene is applied in place of the solvent vapor treatment. Upon drying the feature composition is formed The absorption maximum is 570 my (87 percent absorption) for the unconverted coating and 635 m;t(93 percent absorption), respectively, for the converted coating. Speeds for the coatings are determined forboth positive and negative charging. The speeds of the unconverted coating are ++l00 and 56 whereas the converted coating has speeds of+450 and 500.

Example 8 The procedure of example 1 is repeated using 4-(4- dimethylaminophenyl-Z,6-diphenylthiapyrylium perchlorate as the dye and 90 g. of dichloromethane as the solvent. Two coatings are then formed as in example 1 without the subsequent vapor treatment. The first coating is converted by covering immediately after coating so as to restrict the rate of solvent evaporation. The second coating is converted by immersing briefly in a bath of benzene. After drying, comparisons between converted and unconverted coatings are made. The unconverted coating has speeds of +40 and -30, whereas the first converted coating has a speed of +2,000 and 2,000, while the second converted coating has speeds of +1 ,600 and l ,800.

Example 9 The procedure of example I is repeated using a solvent mixture containing a high boiling solvent. The solvent mixture consists of 81 g. of dichloromethane and 9 g. of toluene. The mixture is coated as in example 1 and allowed to dry at room temperature which results in the solvent being in contact with the coating long enough to cause conversion to the aggregate. The final converted coating has positive and negative speeds of l,800 and 2,l00, respectively.

The following two examples demonstrate the improved results obtained by using a higher viscosity polycarbonate in forming the heterogeneous compositions of the present invention.

Example 10 Control Coating A 35.3-gram portion ofa low viscosity Bisphenol A polycarbonate having an inherent viscosity of about 0.56. 23.5 grams of 4,4'-benzylidenebis (N,N-diethyl-m-toluidine, and 1.2 grams of 4-(4-dimethylaminophenyl)-2,o-diphenylthiapyrylium perchlorate are dissolved in a solvent mixture comprised of 242 ml. of dichloromethane and l50 ml. of 1,1,2- trichloroethane by stirring the solids in the solvent for four hours at room temperature. The resulting solution is then sheared in a water-jacketed high speed shearing blender for 30 minutes in accordance with the procedures described in copending Gramza application, U.S. Ser. No. 674,006, filed Oct. 9, I967. The water in the jacket of the blender is maintained at 50 F. during shearing. The sheared dope is then coated at a coverage of l g./ft. on a poly(ethylene terephthalate) film base carrying a conductive layer ofa sodium salt ofa per i n can be repeatedly chargedmxposed and iofled- 0 polymeric lactone as described in U.S. Pat. NO. 3,260,706.

TABLE 10 Conducting substrate Organic photoconducting layer Density Resistiv- Max. Percent uh- Speed (100 Metal (net) tty, Q/sq. Composition (m sorption v. tov) Nickel .10 10 Polycarbonate of Example l/4,4'-l)enzylidenc-bis(N,N-diethyl-m-tolui- H20 .15 ,0l)0;

di11e)(60/40)+4% 4-(4-din1etliylaminoplienyl)-2,G- liphenyltliiapyryliuni -l, 000 fiuoroborate.

Niehrome .05 10 Polycarbonate of Example 1/4,4-benzylidene-bis(N,N-tliethyl-m-tolut 085 U +2,500; (Driverdine) (/40) +2% 4(4-(limethylaminopelmyl)2,tl-diplicnyltliiapyryliuni 2,500 Harris perchlorate.

Company).

Titaniu 5 106 ycarbonate of Example 1/4,4-benzylidene-bls(N,N-diethyl-m-tolui- 685 am +2, 500;

dine) (60/40)+2% 4(4-dimethylaminopllenyl)2,6-diplienyltliiapyryl-- 2,00U ium perchlorate.

Type 316 .05 10 5 Polycarbonate of Example l/4,4-benzylldene-bis(N,N-diethyl-rn-tolui G .10 +2,50t); stainlesssteel. dine) (60/40)+2% 4(4-din1uthylaniinophcnyl)2,tl diplicuyltltiapyryI 1,.)00

iurn perchlorate.

The coating is allowed to dry and then examined microscopi cally using transmitted light and 450K magnification. it is noted that the coating is heterogeneous in nature. The spectrophotometric transmission characteristics of the coating are then measured and it is found that the coating absorbs 92 percent of incident radiation at 690 mg, 80 percent at 600 mpand 20 percent at 500 mg. The electrophotographic speed of the coating is then measured as in the previous examples and the positive and negative 100-volt toe speeds of the coating are found to be 2,500 and 2,850, respectively for this control coating.

High Viscosity Coating A second coating is made using 16.2 grams of Bisphenol A polycarbonate having an inherent viscosity of 2.70 as measured in l,2-dichloroethane, 10.8 grams of the above photoconductor and 3 grams of the above thiapyrylium dye. The solids are dissolved in a solvent mixture comprises of 228 ml. of 1,2-dichlorethane and 213 ml. of dichloromethane by stirring into the solvents for four hours at room temperature.

The resulting solution is sheared in a water-jacketed high speed shearing blender as in the control coating while maintaining the water temperature at 50 F. The sheared dope is coated at a coverage of l g./ft. on a conducting substrate similar to that used in the control coating. The coating is allowed to dry and examined microscopically using transmitted light 450x magnification. It is noted that the coating contains a very fine grain dense discontinuous phase. This heterogeneous coating is much finer grained than the control coating above. The coating is also examined visually with the unaided eye and it is noted that the surface of the second coating has very little orange peel as compared to the control coating. The spectrophotometric transmission characteristics ofthe coating absorbs over 90 percent of the incident radiation at all wavelengths between 530 m tand 700 mp. The electrophotographic speeds of the coating are measured as in the previous example and it is found that the negative toe speed of this coating is three times faster than the negative toe speed of the control coating. The positive and negative toe speed of the control coating. The positive and negative 100-vo1t toe speeds are 400 and 9,500, respectively. Example 11 Coating A is prepared by dissolving 18 grams of the polycarb'onate binder of example 1 in 201 ml. of dichloromethane by stirring the binder in the solvent for two hours at room temperature. The resulting solution is placed in a water-jacketed high speed shearing blender and 12 grams of photoconductive zinc oxide are added to the solution which thereafter is sheared for ten minutes. The water in the jacket of the blender is maintained at 70 F. during shearing. The sheared dispersion is hand-coated at a 0.008-inch wet coating thickness on a poly(ethylene terepthalate) support having a 0.4 neutral density high vacuum evaporated nickel conducting layer thereon.

The coating block is maintained at a temperature of 70 F.

during coating. Next, coating B is prepared by dissolving 17.6 g. of the polycarbonate binder in 194 ml. of dichloromethane as previously. The resultant solution is then placed in the jacketed high speed shearing blender with the addition of l 1.8 grams of photoconductive zinc oxide and the mixture is sheared for 10 minutes with the water temperature being maintained at 70 F. After shearing, 0.6 grams of 4-(4- dimethylaminophenyl)-2,G-diphenylthiapyrylium perchlorate and 13 m1. of methyl alcohol are simply stirred into the sheared dispersion for 30 minutes at room temperature. The resulting dispersion is hand coated at a 0.008-inch wet coating thickness on a nickel-coated support as above. Next, coating C is prepared by dissolving 17.6 grams of the above polymer and 0.6 grams of the thiapyrylium dye of coating B in 201 ml. of dichloromethane by stirring for two hours at room temperature. The resultant solution is placed in a high speed shearing blender and sheared for 30 minutes after which 11.8 grams of photoconductive zinc oxide are added to the blender followed by additional shearing for 5 minutes with the water in the jacket of the blender being maintained at 70 F. during shear- .2; ing. The sheared dispersion is hand coated as previously onto a similar conducting support. The coatings, A, B, and C are dried in a laboratory oven at 60 C. for 16 hours. The elec trophotographic speeds and spectral characteristics for each of the three coatings are determined and are tabulated in table 1 1 below:

Coating A is prepared by dissolving 3.73 grams of Bisphenol A polycarbonate, 6.07 grams of phenyl-tri(p-diethylaminophenyl)stannane, and 0.2 grams of 4-(4- I drmethylaminophenyl)-2,G-diphenylthiaphyrylium perchlorate in a solvent mixture of 38.3 ml. of

dichloromethane, 23.7 ml. of 1,1,2-trichloroethane, and 5.7 ml. of methanol by stirring the solids in the solvent for 2 hours at 20 C. The resulting solution is hand coated on a nickelcoated subbed poly(ehtylene terephthalate) support as described in example 6, held at a temperature of 20 C. Coating B is prepared by dissolving 3.73 grams of Bisphenol A polycarbonate, 6.07 grams of .phenyl-tri-(pdiethylaminophenyl)stannane and 0.2 grams of 4-(4- dimethylaminophenyl)-2,o-diphenylthiapyrylium perchlorate in a solvent mixture identical to that used for preparing Coating A. Stirring is carried out in the same manner as above, after which the solution is placed in a water-jacketed high speed shearing blender while 20 C. water is circulated through the jacket. The sheared solution is then coated and dried in the same manner as is done for Coating A. Coatings A and B are dried in a laboratory oven held at 60 C. for 16 hours. The electrophotographic speeds and spectral characteristics are determined as in the above examples and the values are shown in table 12 below.

TABLE 12 Speed Positive Negative Max. Percent V0 100 v. V0 100 v. Coating (mp) absorption (volts) toe (volts) toe Example 13 An 8 g. portion of the binder of example 1 and 2 g. of 2,4,7- trinitro-9-fluorenone are dissolved in 67 ml. of dichloromethane by stirring the solids in the solvent for 2 hours at room temperature. The resulting solution is hand coated at an 0.006-inch wet coating thickness on 0.4 neutral density subbed evaporated nickel substrate. The coating block is maintained at 70 F. during coating. A second coating is prepared by dissolving 7.85 g. of the above binder, 1.96 g. of 2,3,7-trinitro-9-fluorenone, and 0.2 g. of 4-(4- dimethylamonophenyl)-2,G-diphenylthiapyrylium perchlorate in a solvent mixture consisting of 63.8 ml. of dichloromethane and 5.7 ml. of methyl alcohol by stirring the solids in the solvent for 2 hours at room temperature. The resulting solution is hand coated at an 0.006-inch wet coating thickness on a poly(ethylene terephthalate) film base carrying a conducting trichloroethane by stirring the solids in the solvent for 2 hours at room temperature. The resulting solution is placed i in a jacketed, high-speed shearing blender and sheared for 30 minutes. The water in the jacket of the blender is maintained at 70 F. while shearing. The sheared material is hand coated as above. The coatings l, 2, and 3 are dried in a laboratory oven at 60 C. for 16 hours. The 100 V. toe speeds and spectral characteristics are determined for each of the coatings as in the previous examples and the values are tabulated in table 13.

TABLE 13 Speed Positive Negative AMax Percent Va 100 v. V 100 v. Coating (mu) absorption (volts) toe (volts) too 1 Unsensltized. 2 Too slow to be measured.

Example l4 A control coating is prepared by dissolving 0.375 g. of 4-(4- dimethylaminophenyl) 2,o-diphenylthiapyrylium fluoroborate, 4.5 g. poly(4,4-isopropylenediphenylcarbonate-block-oxytetramethylene) and 3 g. of 4,4'-benzylidenebis(N,N-diethylmtoluidine 42.5 g. of methylene chloride. The solution is coated on a conducting support as in the preceding example. Next, a similar solution is prepared followed by shearing in a water-jacketed high-speed shearing blender for 30 minutes during which time the water in the jacket is maintained at 70 F. The sheared composition is coated as above to form a second element. The absorption maximum for the control coating is at 585 mu; whereas, the maximum for the converted second coating is at 690 my The resultant second element can be charged imagewise, exposed and developed as in example 1 to form a visible image.

tion that 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.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

I claim:

1. A heterogeneous photoconductive composition comprising an electrically insulating polymeric material having an alkylidene diarylene moiety in the recurring unit, a pyrylium dye which has been solubilized with said polymeric material and a photoconductor, said composition being in the form of a multiphase organic solid comprising a continuous phase of said polymeric material having therein a particulate discontinuous phase containing a combination ofsaid dye and said polymeric material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at a wavelength at least about my. different from the wavelength of maximum absorption of said dye solubilized with said polymeric material in a homogenous composition.

2. The composition as described in claim 1 wherein said dye is selected from the group consisting of a thiapyrylium dye salt, a selenapyrylium dye salt and a pyrylium dye salt.

3. The composition as described in claim 1 wherein said iri sulating polymeric material is selected from the group consisting of carbonate polymers having an alkylidene diarylene moiety in the recurring unit, poly(4,4'-isopropylidenedibenzyl-4,4'-isopropylidene dibenzoate) and poly(4,4'- isopropylidene dibenzyl-4,4-isopropylidene dibenzoate).

4. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 4-[4-bis(2- chloroethyl)aminophenyl]2,6-diphenylthiapyrylium.

5. A composition as described in claim I wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 4-(4- dimethylamino-phenyl)-2,o-diphenylthiapyrylium,

6. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 2,6-bis(4-ethylphenyl)-4-(4-dimethylaminophenyl)thiapyrylium.

7. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 4-(4- dimethylamino-phenyl)-2-(4-ethoxyphenyl)-6-phenylthiapyrylium.

8. A composition as described in claim I wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of an anion selected from the group consisting of 4-(4-dimethylamino-2- methylphenyl)-2,6-diphenylpyrylium, 4-[4-di(2- .A 30 chloroethyl)aminophenyl]2-(4-methoxyphenyl)-6-phenylthiapyrylium, 4-(4-dimethylaminophenyl)-2,6-diphenylthiaprylium,4-(4-dimethylaminophenyl)-2,6-diphenylpyrylium,2-(2,4-dimethoxyphenyl)-4(4-dimethylaminophenyl)benzo(b)pyrylium, and 4-4-dimethylaminophenyl)-2-(4- methoxyphenyl)-6-phenylthiapyrylium.

9. A heterogeneous photoconductive composition containing a dye selected from the group consisting of pyrylium, thiapyrylium and selenapyrylium dye salts and a hydrophobic carbonate polymer having an alkylidene diarylene moiety in a recurring unit, said dye having been solubilized with said polymer, said composition being in the form of a multiphase organic solid comprising a continuous binder phase of said polymer having dispersed therein a particulate discontinuous phase comprising a combination of said dye and said polymer, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at a wavelength at least about 10 m different from the wavelength of maximum absorption of said dye solubilized with said carbonate polymer in a homogeneous composition.

10. A composition as described in claim 9 wherein the pyrylium dye has the formula:

wherein:

R and R, are aryl radicals selected from the group consisting of phenyl and substituted phenyl having at least one substituent selected from the group consisting of an alkyl radical of from i to 6 carbon atoms and an alkoxy radical of from 1 to 6 carbon atoms;

R; is an alkylamino-substituted phenyl radical having from 1 to 6 carbon atoms in the alkyl moiety;

X is selected from the group consisting of sulfur and oxygen;

and

Z'is an anion:

and wherein the hydrophobic polymeric material is a filmforming polymer containing the following recurring unit:

wherein:

R is a phenylene radical and each of R., and R when taken separately, is selected from the group consisting of a hydrogen atom, alkyl radical of from I to 10 carbon atoms and a phenyl radical and Rj and R when taken together, are the carbon atoms neces sary to form a cyclic hydrocarbon radical, the total number ofcarbon atoms in R and R being up to 19.

11. An electrophotographic element comprising an electrically conductive support having thereon at least one heterogeneous photoconductive composition comprising an electrically insulating polymeric material having an alkylidene diarylene moiety in the recurring unit, a pyrylium dye which has been solubilized with said polymeric material and a photoconductor, said composition being in the form ofa multiphase organic solid comprising a continuous phase of said polymeric material having therein a particulate discontinuous phase containing a combination of said dye and said polymeric material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition, when bearing an electrostatic charge on a surface thereof, being capable of losing the charge in proportion to the intensity of incident light striking said surface of the composition, the light energy in meter-candle-seconds incident said surface capable of causing a IOO-volt reduction in said charge is not more than 200 meter-candle-seconds and said composition being characterized by an ability to absorb radiation in a wavelength range different from the wavelength range for a homogeneous composition containing said dye solubilized with said polymeric material.

12. Anelement as described in claim 11 wherein the composition contains an organic photoconductor different from said dye.

13. An element as described in claim 12, wherein said photoconductor is 4,4-benzylidenebis(N,N-diethyl-mtoluidine), said dye being present in an amount of from about 0.001 to about 30 percent by weight of said composition and said dye being selected from the group consisting of 4-(4-bis(2 -chloroethy1)aminophenyl]-2,6-diphenylthiapyrylium perchlorate; 4-(4-dimethylaminophenyl-2,-diphenylthiapyrylium perchlorate; 4-(4-dimethylaminophenyl-2,6-diphenylthiapyrylium fluoroborate; 4-(4-dimethylamino-2- methylphenyl)2,6-diphenylpyrylium perchlorate; 4-(4- dimethyl-aminophenyl)-2,6-diphenylthiapyrylium ptoluenesulfonate; 4-(4dimethylaminophenyl)-2-(4- methoxyphenyl)-6-phenylthiapyrylium perchlorate and 4-(4- dimethylaminophenyl)-2-(4-ethoxyphenyl)-6-phenylthiapyrylium perchlorate.

14. A method for forming a composition which is capable of responding to differences in light intensity by exhibiting a dif ferential conductivity when disposed to receive modulated electromagnetic radiation comprising the steps of solubilizing a pyrylium dye with a hydrophobic carbonate polymer having an alkylidene diarylene moiety in a recurring unit, coating a layer of the solubilized dye and polymer on a support, subjecting the layer to solvent for said dye and polymer whereby a heterogeneous two-phase material is formed in situ in said layer, said two phases being visible under 2500X magnification, the continuous organic binder phase of said carbonate polymer having dispersed therein a discontinuous phase of said material containing a significant portion of said dye in combination with said polymer and said material having a maximum radiation absorption at a wavelength at least about l mudifferent from the wavelength of maximum absorption ofsaid dye solubilized with said polymer.

15. The method of claim 14, wherein the solvent used is a halogenated hydrocarbon solvent.

16. The method of claim 14 wherein the coated layer is subjected to the solvent in vapor form for a time sufficient to form the heterogeneous two-phase material.

17. The method of claim 14 wherein the coated layer is subjected to the solvent by overcoating with the solvent in liquid form for a time sufficient to form the heterogeneous twophase material.

18. A heterogeneous photoconductive composition containing an electrically insulating polymeric material having an alkylidene diarylene moiety in the recurring unit and a pyrylium dye which has been solubilized with said polymeric material, said composition being in the form of a multiphase organic solid comprising a continuous binder phase of said polymeric material having dispersed therein a particulate discontinuous phase comprising a combination of said dye and said polymeric material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at a wavelength at least about mp different from the wavelength of maximum absorption of said dye solubilized with said polymeric material in a homogeneous composition.

19. A composition as described in claim 18 wherein the pyrylium dye has the formula:

wherein:

R and R are aryl radicals selected from the group consisting of phenyl and substituted phenyl having at least one substituent selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms and an alkoxy radical of from 1 to 6 carbon atoms;

R is an alkylamino-substituted phenyl radical having from 1 to 6 carbon atoms in the alkyl moiety;

X is selected from the group consisting of sulfur and oxygen;

and

Z'is an anion;

and wherein the polymeric material is a film-forming polymer containing the following moiety in a recurring unit:

R11 R; R7 Qs M.

it. w

wherein:

each of R and R when taken separately, is selected from the group consisting of a hydrogen atom, an alkyl radical of from 1 to 10 carbon atoms and a phenyl radical, and R and R when taken together, are the carbon atoms necessary to form a cyclic hydrocarbon radical, the total of carbon atoms in R and R being up to 19;

R and R are each selected from the group consisting of hydrogen, alkyl radicals of from I to 5 carbon atoms, alkogry radicals of from 1 to 5 carbon atoms and a halogen; an

R is selected From the group consisting of divalent radicals having the formulas:

said composition comprising a combination of said dye and carbonate polymer, the individual portions of said discontinuous phase having a size of about 0.01 to about 25 microns, and said composition having a radiation wavelength range of absorption different from the wavelength range of absorption of a homogeneous composition comprised of said dye solubilized in said polymer, said heterogeneous composition when bearing an electrostatic charge on a surface thereof being capable of losing said electrostatic charge in proportion to the intensity of incident actinic radiation such that the incident radiation energy in meter-candle-seconds required to cause a l-volt reduction in the charge is not greater than about 200 metercandle-seconds.

21. An electrophotographic element as described in claim 20 wherein said carbonate polymer has an inherent viscosity no greater than about I.

22. In an electrophotographic process wherein an electrostatic charge pattern is formed on a photoconductive element, the improvement wherein said element has a photoconductive layer comprising an organic photoconductor in a heterogeneous composition comprising an electrically insulating polymeric material having an alkylidene diarylene moiety in a recurring unit and a pyrylium dye which has been solubilized with said polymer material, said composition being in the form of a multiphase organic solid comprising a continuous phase of said polymer material having therein a particulate discontinuous phase containing a combination of said dye and said polymer material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at least about [0 mp. different from the wavelength of maximum absorption of said dye solubilized with said polymeric material in a homogeneous composition.

imum of said dye solubilized with said polycarbonate.

24. An electrophotographic element comprising a conductive support having thereon a layer of a heterogeneous photoconductive composition comprising a continuous organic binder phase having dispersed therein a discontinuous phase comprising an organic photoconductor sensitized with a particulate combination of a carbonate polymer having an alkylidene diarylene moiety in a recurring unit and a thiapyrylium dye salt, said dye salt having been solubilized with said carbonate polymer, said particulate combination having a size of about 0.01 to 25p, and said combination having a wavelength of maximum radiation absorption which is at least l0m different from the radiation absorption maximum of said dye dissolved with said carbonate polymer in a homogeneous composition.

25. An electrophotographic element as described in claim 24 wherein said dye salt is selected from the group consisting of fluoroborate and perchlorate salts of 4-(4-dimethylaminophenyl)-2,6-diphenylthiapyrylium and 4-(4- dimethylamino-phenyl)-2- (4-ethoxyphenyl-6-phenylthiapyrylium.

26. An electrophotographic element as described in claim 24 wherein said carbonate polymer is poly(4,4'-isopropylidenediphenylene carbonate).

Claims

2. The composition as described in claim 1 wherein said dye is selected from the group consisting of a thiapyrylium dye salt, a selenapyrylium dye salt and a pyrylium dye salt.
3. The composition as described in claim 1 wherein said insulating polymeric material is selected from the group consisting of carbonate polymers having an alkylidene diarylene moiety in the recurring unit, poly(4,4-isopropylidene-dibenzyl-4, 4''-isopropylidene dibenzoate) and poly(4,4''-isopropylidene dibenzyl-4,4''-isopropylidene dibenzoate).
4. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 4-(4-bis(2-chloroethyl)aminophenyl)-2,6-diphenylthiapyrylium.
5. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 4-(4-dimethylamino-phenyl)-2,6-diphenylthiapyrylium,
6. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 2,6-bis(4-ethyl-phenyl)-4-(4-dimethylaminophenyl)thiapyrylium.
7. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of 4-(4-dimethylamino-phenyl)-2-(4-ethoxyphenyl)-6-phenylthiapyrylium.
8. A composition as described in claim 1 wherein said dye is selected from the group consisting of perchlorate, fluoroborate and p-toluenesulfonate salts of an anion selected from the group consisting of 4-(4-dimethylamino-2-methylphenyl)-2,6-diphenylpyrylium, 4-(4-di(2-chloroethyl)aminophenyl)-2-(4-methoxyphenyl)-6-phenylthiapyrylium, 4-(4-dimeThylaminophenyl)-2, 6-diphenyl-thiaprylium,4-(4-dimethylaminophenyl)-2,6-diphenylpyrylium,2-(2,4-dimethoxyphenyl)-4-(4-dimethylaminophenyl)benzo(b)pyrylium, and 4-4-dimethylaminophenyl)-2-(4-methoxyphenyl)-6-phenylthiapyrylium.
9. A heterogeneous photoconductive composition containing a dye selected from the group consisting of pyrylium, thiapyrylium and selenapyrylium dye salts and a hydrophobic carbonate polymer having an alkylidene diarylene moiety in a recurring unit, said dye having been solubilized with said polymer, said composition being in the form of a multiphase organic solid comprising a continuous binder phase of said polymer having dispersed therein a particulate discontinuous phase comprising a combination of said dye and said polymer, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at a wavelength at least about 10 m Mu different from the wavelength of maximum absorption of said dye solubilized with said carbonate polymer in a homogeneous composition.
10. A composition as described in claim 9 wherein the pyrylium dye has the formula: wherein: R1 and R2 are aryl radicals selected from the group consisting of phenyl and substituted phenyl having at least one substituent selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms and an alkoxy radical of from 1 to 6 carbon atoms; R3 is an alkylamino-substituted phenyl radical having from 1 to 6 carbon atoms in the alkyl moiety; X is selected from the group consisting of sulfur and oxygen; and Z is an anion: and wherein the hydrophobic polymeric material is a film-forming polymer containing the following recurring unit: wherein: R is a phenylene radical and each of R4 and R5, when taken separately, is selected from the group consisting of a hydrogen atom, alkyl radical of from 1 to 10 carbon atoms and a phenyl radical and Rj4 and R5, when taken together, are the carbon atoms necessary to form a cyclic hydrocarbon radical, the total number of carbon atoms in R4 and R5 being up to 19.
11. An electrophotographic element comprising an electrically conductive support having thereon at least one heterogeneous photoconductive composition comprising an electrically insulating polymeric material having an alkylidene diarylene moiety in the recurring unit, a pyrylium dye which has been solubilized with said polymeric material and a photoconductor, said composition being in the form of a multiphase organic solid comprising a continuous phase of said polymeric material having therein a particulate discontinuous phase containing a combination of said dye and said polymeric material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition, when bearing an electrostatic charge on a surface thereof, being capable of losing the charge in proportion to the intensity of incident light striking said surface of the composition, the light energy in meter-candle-seconds incident said surface capable of causing a 100-volt reduction in said charge is not more than 200 meter-candle-seconds and said composition being characterized by an ability to absorb radiation in a wavelength range different from the wavelength range for a homogeneous composition containing said dye solubilized with said polymeric material.
12. An element as described in claim 11 wherein the composition contains an organic photoconductor different from said dye.
13. An element as described in claim 12, wherein said photoconductor is 4,4''-benzylidenebis(N,N-diethyl-m-toluidine), said dye being preseNt in an amount of from about 0.001 to about 30 percent by weight of said composition and said dye being selected from the group consisting of 4-(4-bis(2-chloroethyl)aminophenyl)-2,6-diphenylthiapyrylium perchlorate; 4-(4-dimethylaminophenyl-2,6-diphenylthiapyrylium perchlorate; 4-(4-dimethylaminophenyl-2,6-diphenylthiapyrylium fluoroborate; 4-(4-dimethylamino-2-methylphenyl)2,6-diphenylpyrylium perchlorate; 4-(4-dimethyl-aminophenyl)-2,6-diphenylthiapyrylium p-toluenesulfonate; 4-(4-dimethylaminophenyl)-2-(4- methoxyphenyl)-6-phenylthiapyrylium perchlorate and 4-(4-dimethylaminophenyl)-2-(4-ethoxyphenyl)-6-phenylthiapyrylium perchlorate.
14. A method for forming a composition which is capable of responding to differences in light intensity by exhibiting a differential conductivity when disposed to receive modulated electromagnetic radiation comprising the steps of solubilizing a pyrylium dye with a hydrophobic carbonate polymer having an alkylidene diarylene moiety in a recurring unit, coating a layer of the solubilized dye and polymer on a support, subjecting the layer to solvent for said dye and polymer whereby a heterogeneous two-phase material is formed in situ in said layer, said two phases being visible under 2500X magnification, the continuous organic binder phase of said carbonate polymer having dispersed therein a discontinuous phase of said material containing a significant portion of said dye in combination with said polymer and said material having a maximum radiation absorption at a wavelength at least about 10 m Mu different from the wavelength of maximum absorption of said dye solubilized with said polymer.
15. The method of claim 14, wherein the solvent used is a halogenated hydrocarbon solvent.
16. The method of claim 14 wherein the coated layer is subjected to the solvent in vapor form for a time sufficient to form the heterogeneous two-phase material.
17. The method of claim 14 wherein the coated layer is subjected to the solvent by overcoating with the solvent in liquid form for a time sufficient to form the heterogeneous two-phase material.
18. A heterogeneous photoconductive composition containing an electrically insulating polymeric material having an alkylidene diarylene moiety in the recurring unit and a pyrylium dye which has been solubilized with said polymeric material, said composition being in the form of a multiphase organic solid comprising a continuous binder phase of said polymeric material having dispersed therein a particulate discontinuous phase comprising a combination of said dye and said polymeric material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at a wavelength at least about 10 m Mu different from the wavelength of maximum absorption of said dye solubilized with said polymeric material in a homogeneous composition.
19. A composition as described in claim 18 wherein the pyrylium dye has the formula: wherein: R1 and R2 are aryl radicals selected from the group consisting of phenyl and substituted phenyl having at least one substituent selected from the group consisting of an alkyl radical of from 1 to 6 carbon atoms and an alkoxy radical of from 1 to 6 carbon atoms; R3 is an alkylamino-substituted phenyl radical having from 1 to 6 carbon atoms in the alkyl moiety; X is selected from the group consisting of sulfur and oxygen; and Z is an anion; and wherein the polymeric material is a film-forming polymer containing the following moiety in a recurring unit: wherein: each of R4 and R5, when taken separately, iS selected from the group consisting of a hydrogen atom, an alkyl radical of from 1 to 10 carbon atoms and a phenyl radical, and R4 and R5, when taken together, are the carbon atoms necessary to form a cyclic hydrocarbon radical, the total of carbon atoms in R4 and R5 being up to 19; R6 and R7 are each selected from the group consisting of hydrogen, alkyl radicals of from 1 to 5 carbon atoms, alkoxy radicals of from 1 to 5 carbon atoms and a halogen; and R8 is selected From the group consisting of divalent radicals having the formulas:
20. An electrophotographic element comprising a conductive support having coated thereon a heterogeneous photoconductive composition comprising a polyarylalkane photoconductor, a carbonate polymer having an alkylidene diarylene moiety in a recurring unit and an organic dye selected from the group consisting of a pyrylium dye salt and a thiapyrylium dye salt which has been solubilized with said polymer, the continuous organic binder phase of said carbonate polymer having dispersed therein; a discontinuous phase of said composition comprising a combination of said dye and carbonate polymer, the individual portions of said discontinuous phase having a size of about 0.01 to about 25 microns, and said composition having a radiation wavelength range of absorption different from the wavelength range of absorption of a homogeneous composition comprised of said dye solubilized in said polymer, said heterogeneous composition when bearing an electrostatic charge on a surface thereof being capable of losing said electrostatic charge in proportion to the intensity of incident actinic radiation such that the incident radiation energy in meter-candle-seconds required to cause a 100-volt reduction in the charge is not greater than about 200 meter-candle-seconds.
21. An electrophotographic element as described in claim 20 wherein said carbonate polymer has an inherent viscosity no greater than about 1.
22. In an electrophotographic process wherein an electrostatic charge pattern is formed on a photoconductive element, the improvement wherein said element has a photoconductive layer comprising an organic photoconductor in a heterogeneous composition comprising an electrically insulating polymeric material having an alkylidene diarylene moiety in a recurring unit and a pyrylium dye which has been solubilized with said polymer material, said composition being in the form of a multiphase organic solid comprising a continuous phase of said polymer material having therein a particulate discontinuous phase containing a combination of said dye and said polymer material, the individual portions of said discontinuous phase having a size of about 0.01 to 25 microns, said composition having a maximum radiation absorption at least about 10 m Mu different from the wavelength of maximum absorption of said dye solubilized with said polymeric material in a homogeneous composition.
23. A heterogeneous photoconductive composition comprising a continuous organic binder phase having dispersed therein photoconductive zinc oxide sensitized with a particulate combination of a hydrophobic polycarbonate having an alkylidene diarylene moiety in a recurring unit and a pyrylium dye selected from the group consisting of a thiapyrylium, a pyrylium and a selenapyrylium salt, said dye having been solubilized with said polycarbonate, said particulate combination having a size of about 0.01 to 25 microns, and said sensitizer having a wavelength of maximum radiation absorption which is at least 10 m Mu different from the radiation absorption maximum of said dye solubilized with said polycarbonate.
24. An electrophotographic element comprising a conductive support having thereon a layer of a heterogeneous photoconductive composition comprising a continuous organic binder phase having dispersed theRein a discontinuous phase comprising an organic photoconductor sensitized with a particulate combination of a carbonate polymer having an alkylidene diarylene moiety in a recurring unit and a thiapyrylium dye salt, said dye salt having been solubilized with said carbonate polymer, said particulate combination having a size of about 0.01 to 25 Mu , and said combination having a wavelength of maximum radiation absorption which is at least 10m Mu different from the radiation absorption maximum of said dye dissolved with said carbonate polymer in a homogeneous composition.
25. An electrophotographic element as described in claim 24 wherein said dye salt is selected from the group consisting of fluoroborate and perchlorate salts of 4-(4-dimethyl-aminophenyl)-2,6-diphenylthiapyrylium and 4-(4-dimethylamino-phenyl)-2- (4-ethoxyphenyl-6-phenylthiapyrylium.
26. An electrophotographic element as described in claim 24 wherein said carbonate polymer is poly(4,4''-isopropylidenediphenylene carbonate).