United States Patent (15) 3,647,432 Holstead (45) Mar
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United States Patent (15) 3,647,432 Holstead (45) Mar. 7, 1972 (54) CARBAZOLYLMETHANEDYE SALTS 3,503,740 3/1970 De Selms et al..........................96/15 ASSENSTAERS FOR PHOTOCONDUCTOR COMPOSTIONS Primary Examiner-George F. Lesmes 72) Inventor: Colin Holstead, 37 Abbotts Road Abbotts Assistant Examiner-John C. Cooper, Langley, Walford, England Attorney-William H. J. Kline, James R. Frederick and Fred 22 Filed: Oct. 22, 1969 L. Denson 21 Appl. No.: 868,600 57 ABSTRACT 52 U.S.C.......................................96/16,96/1.5, 96/1.7, Tris(9-alkylcarbazol-3-yl)methane dyes and tris(9-arylcar 260/215 bazol-3-yl)methane dyes enhance the sensitization of 51 int. Clk........................................G03g S/06, G03g 5/08 photoconductive layers containing various photoconductors. 58 Field of Search.............................................96/1.5-1.7; These materials are particularly useful in elements used in 260/315 electrophotographic processes. 56 References Cited 15Claims, NoDrawings UNITED STATES PATENTS 3,448,705 l/1970 Fox et al................................96/1.6 3,647,432 1. 2 It is a further object of this invention to provide a process CARBAZOLYLMETHANEDYE SALTS ASSENSTIZERS for using novel sensitized photoconductive elements. FORPHOTOCONDUCTOR COMPOSITIONS These and other objects are accomplished by using either a This invention relates to electrophotography, and in par tris(9-alkyl carbazol-3-yl)methane dye or a tris(9-arylcar ticular to novel sensitized photoconductive compositions and bazol-3-yl)methane dye as a sensitizer for a photoconductive elements having coated thereon such compositions. composition. The carbazole nucleus of these dyes can be The process of xerography, as disclosed by Carlson in U.S. further substituted by additional groups such as alkoxy, Pat. No. 2,297,691, employs an electrophotographic element aryloxy, alkyl, acyl, halogen, etc. The use of photoconductive comprising a support material bearing a coating of a normally compositions containing the sensitizing dyes of this invention insulating material whose electrical resistance varies with the 10 in electrophotographic elements increases the speed of such amount of incident actinic radiation it receives during an elements when exposed in an electrophotographic process imagewise exposure. The element, commonly termed a compared to the speeds attainable when the sensitizer is ab photoconductive element, is first given a uniform surface sent. When the sensitizer is not present in the photoconduc charge, generally in the dark after a suitable period of dark tive layer, the resultant speed of the layer is frequently not fast adaptation. It is then exposed to a pattern of actinic radiation 15 enough to produce a developable electrostatic latent image. which has the effect of differentially reducing the potential of The preferred sensitizing dyes described herein have the fol the surface charge in accordance with the relative energy con lowing formula: tained in various parts of the radiation pattern. The dif ferential surface charge or electrostatic latent image remain ing on the electrophotographic element is then made visible 20 by contacting the surface with a suitable electroscopic mark R ing material. Such marking material or toner, whether con tained in an insulating liquid or on a dry carrier, can be deposited on the exposed surface in accordance with either the charge pattern or the absence of charge pattern as desired. 25 The deposited marking material may then be either per manently fixed to the surface of the sensitive element by known means such as heat, pressure, solvent vapor, or the R like, or transferred to a second element to which it may similarly be fixed. Likewise, the electrostatic latent image can 30 be transferred to a second element and developed there. Various photoconductive insulating materials have been employed in the manufacture of electrophotographic ele ments. For example, vapors of selenium and vapors of seleni um alloys deposited on a suitable support and particles of wherein: photoconductive zinc oxide held in a resinous, film-forming R represents any of the following binder have found wide application in present-day document 1. an aliphatic group having one to 18 carbon atoms e.g., copying applications. methyl, ethyl, propyl, butyl, isobutyl, octyl, dodecyl, etc. Since the introduction of electrophotography, a great many 40 including a substituted alkyl group having one to 18 car organic compounds have also been screened for their bonatoms such as photoconductive properties. As a result, a very large number a. alkoxyalkyl e.g., ethoxypropyl, methoxybutyl, propox of organic compounds are known to possess some degree of ymethyl, etc., photoconductivity. Many organic compounds have revealed a b. aryloxyalkyl e.g., phenoxyethyl, naphthoxymethyl, useful level of photoconduction and have been incorporated 45 phenoxypenty, etc., into photoconductive compositions. Optically clear organic c. aminoalkyl, e.g., aminobutyl, aminoethyl, photoconductor-containing elements having desirable elec aminopropyl, etc., trophotographic properties can be especially useful in elec d. hydroxyalkyl e.g., hydroxypropyl, hydroxyoctyl, etc., trophotography. Such electrophotographic elements may be e.aralkyl e.g., benzyl, phenethyl, etc., exposed through a transparent base if desired, thereby provid 50 f. alkylaminoalkyl C.9. methylaminopropyl, ing unusual flexibility in equipment design. Such composi methylaminoethyl, etc., and also including dial tions, when coated as a film or layer on a suitable support also kylaminoalkyl e.g., diethylaminoethyl, yield an element which is reusable; that is, it can be used to dimethylaminopropyl, propylaminooctyl, etc., form subsequent images after residual toner from prior images g. arylaminoalkyl, e.g., phenylaminoalkyl, diphen has been removed by transfer and/or cleaning. 55 ylaminoalkyl, N-phenyl-N-ethylaminopentyl N-phenyl Although some of the organic photoconductors comprising N-ethylaminohexyl, naphthylaminomethyl, etc., the materials described are inherently light sensitive, their h. nitroalkyl, e.g., nitrobutyl, nitroethyl, nitropentyl, etc., degree of sensitivity is usually low and in the shortwavelength i. cyanoalkyl, e.g., cyanopropyl, cyanobutyl, cyanoethyl, portion of the spectrum so that it is common practice to add materials to increase the speed and to shift the sensitivity 60 etc., toward the longer wavelength portion of the visible spectrum. j. haloalkyl, e.g., chloromethyl, bromopentyl, chlorooc Increasing the speed and shifting the sensitivity of such tyl, etc., systems into the visible region of the spectrum has several ad k. alkyl substituted with an acyl group having the formula vantages: it makes available inexpensive and convenient light sources such as incandescent lamps; it reduces exposure time; 65 O it makes possible the recording of a wide range of colors in --R proper tonal relationship, and allows projection printing through various optical systems. By increasing the speed wherein R is hydroxy, hydrogen, aryl, e.g., phenyl, naphthyl, through the use of sensitizers, photoconductors which would etc., lower alkyl having one to 8 carbon atoms e.g., methyl, otherwise have been unsatisfactory are useful in processes 70 ethyl, propyl, etc., amino including substituted amino e.g., where high speeds are required such as document copying. diloweralkylamino, lower alkoxy having one to 8 carbon It is therefore an object of this invention to provide novel atoms e.g., butoxy, methoxy, etc., aryloxy e.g., phenoxy, sensitized photoconductive elements. naphthoxy, etc.; or It is another object of this invention to provide novel sen 2. an aryl group, e.g., phenyl, naphthyl anthryl, fluorenyl, sitized photoconductive compositions. 75 etc., including a substituted aryl group such as 3,647,432 3 4 a. alkoxyaryl, e.g., ethoxyphenyl, methoxyphenyl, 5. substituted acyl such as those having the formula propoxynaphthyl, etc., b. aryloxyaryl, e.g., phenoxyphenyl, naphthoxyphenyl, phenoxynaphthyl, etc. - i. c. aminoaryl, e.g., aminophenyl, aminonaphthyl, aminoanthryl, etc., wherein R is hydroxy, halogen, e.g., chlorine, bromine, etc., d. hydroxyaryl, e.g., hydroxyphenyl, hydroxynaphthyl, hydrogen, aryl e.g., phenyl, naphthyl, etc., amino including hydroxyanthryl, etc., substituted amino e.g., diloweralkylamino, lower alkoxy hav e. biphenylyl, ing one to 8 carbon atoms e.g., butoxy, methoxy, etc., aryloxy f. alkylaminoaryl, C-9., methylaminophenyl, 10 e.g., phenoxy, naphthoxy, etc., alkyl e.g., methyl, ethyl, methylaminonaphthyl, etc. and also including dial propyl, etc.; kylaminoaryl, e.g., diethylaminophenyl, 6. halogen such as chlorine, bromine, fluorine, or iodine; dipropylaminophenyl, etc., and arylaminoaryl, e.g., phenylaminophenyl, diphen X represents an acid anion such as a halide e.g., chloride, g. 5 bromide, fluoride, iodide, perchlorate, tetrafluoroborate, ylaminophenyl, N-phenyl-N-ethylaminophenyl, sulfamate, thiocyanate, p-toluenesulfonate, methyl sulfate, naphthylaminophenyl, etc., etc. h. nitroaryl e.g., nitrophenyl, nitronaphthyl, nitroanthryl, Typical dyes which belong to the herein described general etc., class of sensitizing compounds include the following: i. cyanoaryl, e.g., cyanophenyl, cyanonaphthyl, 20 cyanoanthry, etc., TABLE I j. haloary, e.g., chlorophenyl, bromophenyl, I. Tris(9-methylcarbazol-3-yl)methane dye chloronaphthyl, etc., II. Tris(9-methyl-6-methoxycarbazol-3-yl)methane dye k. aryl substituted with an acyl group having the formula III. Tris(9-methyl-6-phenoxycarbazol-3-yl)methane