Electrophotographic material containing sensitizers

Abstract

An electrophotographic material is provided herein which comprises a conductive support layer and a photoconductive insulating layer, the latter layer comprising a photoconductive polymeric compound such as poly-N-vinylcarbazole, and a sensitizer having the following general formula ##SPC1##WhereinB represents a radical selected from the group consisting of ##SPC2## ##SPC3##Compounds falling under the latter general formula include such compounds as 2-phenyl-4-[(2'-phenyl-4'-benzopyranylidene) benzyl]-benzopyrylium perchlorate and 2,3-phenyl-4-[(2'-phenyl 4'-benzopyranylidene)benzyl]-6-methylbenzopyrylium perchlorate.

Description

This invention relates to novel light-sensitive layers and more particularly to electrophotographic light-sensitive polymer layers.

Various light-sensitive layers are well known in the electrophotographic art for making copies of documents, drawings, transparencies, etc. These layers contain organic photoconductive compounds, such as poly-N-vinylcarbazole, brominated poly-N-vinylcarbazoles, polyacenaphthylene, etc. These layers are non-conductors of electricity before exposure and become electrical conductors upon exposure.

It is necessary for the electrophotographic art that the photoconductive material has a high photoconductivity in the long wavelength region of the visible spectrum. Such a photoconductive material makes it possible for the electrophotograph art to employ inexpensive and convenient light sources such as incandescent lamps in a reduced exposure time and to reproduce colored pictures. The photoconductive materials mentioned above, however, have usually a low photoconductivity and spectrum characteristics sensitive to the short wavelength region of the exposure light and do not satisfy entirely the above requirement.

It is known that an addition of a so-called sensitizer can improve photoconductivity and spectrum characteristics of the above photoconductive compounds. Conventional sensitizers are dyestuff compounds, such as triarylmethane dyes, xanthene dyes, triazine dyes or acridine dyes, but the conventional sensitizers are not entirely satisfactory to improve the photoconductivity and the spectrum characteristics of the available photoconductive compounds.

In addition to the high photoconductivity and spectrum characteristics sensitive to visible light, the electrophotographic art requires a high electric resistance of photoconductive materials in the dark. Conventional sensitizers are apt to increase the dark conductivity whereas they promote the photoconductivity. A high dark conductivity of photoconductive materials is not desirable because it results in a loss of the applied electrostatic charge in the dark.

An object of the invention is to provide electrophotographic materials having a high photoconductivity and spectrum characteristics sensitive to a long wavelength region of the visible spectrum.

Another object of the invention is to provide electrophotographic materials having a high electric resistance in the dark.

These and other objects are accomplished by adding a new sensitizer shown hereinafter to a photoconductive polymeric compound such as poly-N-vinylcarbazole, brominated poly-N-vinylcarbazole or polyacenaphthylene, as a light-sensitive film-forming composition.

The invention is further explained in the following description with reference to the accompanying drawings wherein:

FIG. 1 represents the wedge spectrogram for an electrophotographic material coated with an unsensitized solution of 10 weight percent of brominated poly-N-vinylcarbazole in chlorobenzene.

FIG. 2 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)-met hyl]benzopyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 3 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-styryl-3-phenyl-4-[(2'-styryl-4'-benzopyranylidene)methyl]-6-methylbenzo pyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 4 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-p-methoxystyryl-4-[2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranyliden e)methyl]benzopyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 5 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-p-methoxystyryl-4-[(2'-phenyl-4'-benzothiopyranylidene)-methyl]benzopyry lium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 6 represents the wedge spectrogram for an electrophotograph material coated with a solution containing 10 weight percent of brominated poly-N-vinyl carbazole sensitized with 0.04 weight percent of 2-[(2'-phenyl-4'-benzopyranylidene)methyl]3-phenylbenzopyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four parts of chlorobenzene and one weight part of dichloroethane.

FIG. 7 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-[(4'-benzothiopyranylidene)methyl]-3-phenylbenzopyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 8 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene)methyl]-3-pheny lbenzopyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

FIG. 9 represents the wedge spectrogram for an electrophotographic material coated with a solution containing 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.04 weight percent of 2-[(2'-phenyl-4'-benzothiopyranylidene)methyl]-3-phenyl-benzopyrylium perchlorate, the brominated poly-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one weight part of dichloroethane.

The new sensitizer, according to the present invention has the following formula: ##SPC4##

where B represents a radical selected from the group consisting of, ##SPC5## ##SPC6##

R.sub.1 is hydrogen, phenyl or an ethenyl or an ethenyl radical selected from the group consisting of styryl,p-methoxystyryl, 3,4-dimethoxystyryl, .alpha.-phenylstyryl, .alpha.-phenyl-p-methoxystyryl, .beta.-furyl(.alpha.')ethenyl and .alpha.-phenyl-.beta.-furyl(.alpha.')-ethenyl;

R.sub.2 is hydrogen or phenyl;

R.sub.3 is hydrogen, methyl or phenyl;

R.sub.4 is hydrogen or phenyl;

R.sub.5 is hydrogen, phenyl or an ethenyl radical selected from the group consisting of styryl, p-methoxystyryl, 3,4-dimethoxystyryl, .alpha.-phenyl-p-methoxystyryl, .beta.-furyl(.alpha.')ethenyl and .alpha.-phenyl-.beta.-furyl(.alpha.')ethenyl;

R.sub.6 is hydrogen or phenyl;

R.sub.7 is hydrogen, methyl or phenyl;

R.sub.8 is hydrogen or phenyl; .Iadd.

R.sub.9 is hydrogen or p-methoxyphenyl; .Iaddend.

the anion is anionic function selected from the group consisting of perchlorate, fluoroborate, chloroferrate, chlorozincate and nitrate; and

X is oxygen or sulfur atom.

The sensitizers having the formula above mentioned are prepared by the following chemical equations A or B: ##SPC7##

In the case of Equation A, 4-[(4'-benzopyranylidene)-methyl]benzopyrylium derivative (III) is obtained by an addition reaction of 4-methoxybenzopyrylium o-nitrobenzene sulfonate (I) with a benzopyrylium salt (II) in an acetic anhydride solution. The benzopyrylium salt has an active methyl or methylene radical.

In the case of Equation B, 2-[(4'-benzopyranylidene)-methyl]benzopyrylium derivative (V) is obtained by an addition reaction of 4-methoxybenzopyrylium o-nitrobenzene sulfonate (I) with a benzopyrylium salt (IV) in an acetic anhydride solution. The benzopyrylium salt has an active methyl radical.

In both cases, methyl 2,4-dinitrobenzene sulfonate, dimethyl sulfate or methyl iodide can be used instead of methyl o-nitrobenzene sulfonate.

Representative examples of the benzopyranylidenemethylbenzopyrylium salts and benzothiopyranylidene-methylbenzopyrylium salts according to the invention are listed in Table I.

Table 1 ______________________________________ Compound Number Name of Compound ______________________________________ 1. 2-phenyl-4-[(2'-phenyl-4'-benzopyranylidene)benzyl]-benzopyrylium perchlorate 2. 2,3-diphenyl-4-[(2'-phenyl-4'-benzopyranylidene)-benzyl]-6-methylbe nzopyrylium perchlorate 3. 2,3-diphenyl-4-[(2'-phenyl-4'-benzopyranylidene)-methyl]-6-methylbe nzopyrylium perchlorate 4. 2,3-diphenyl-4-[(2'-phenyl-4'-benzopyranylidene)-methyl]-6-phenylbe nzopyrylium perchlorate 5. 2-p-methoxystyryl-4-[(2'-phenyl-4'-benzopyranylidene)-methyl]benzop yrylium perchlorate 6. 2-.beta.-furyl(.alpha.')ethenyl-4-[(2'-phenyl-4'-benzopyranylidene- methyl]benzopyrylium perchlorate 7. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylide ne)methyl]benzopyrylium perchlorate 8. 2-styryl-3-phenyl-4-[(2'-phenyl-4'-benzopyranylidene)-methyl]-6-met hylbenzopyrylium perchlorate 9. 2-p-methoxystyryl-3-phenyl-4-[(2'-phenyl-4'-benzopyranylidene)methy l]-6-methylbenzopyrylium perchlorate 10. 9-[(2'-phenyl-4'-benzopyranylidene)methyl]xanthylium perchlorate 11. 2-.beta.-furyl(.alpha.')ethenyl-3-phenyl-4-[(2'-phenyl-4'-benzopyra nylidene)methyl]-6-methylbenzopyrylium perchlorate 12. 2,3-diphenyl-4-[(2'-styryl-4'-benzopyranylidene)benzyl]-6-methylben zopyrylium perchlorate 13. 2-phenyl-4-[(2'-styryl-4'-benzopyranylidene)benzyl]benzopyrylium perchlorate 14. 2,3-diphenyl-4-[(2'-styryl-4'-benzopyranylidene)methyl]-6-methylben zopyrylium perchlorate 15. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-styryl-4'-benzopyranylide ne)methyl]benzopyrylium perchlorate 16. 2-styryl-3-phenyl-4-[(2'-styryl-4'-benzopyranylidene)methyl]-6-meth ylbenzopyrylium perchlorate 17. 9-[(2'-styryl-4'-benzopyranylidene)methyl]xanthylium perchlorate 18. 2-p-methoxystyryl-3-phenyl-4-[(2'-styryl-4' -benzopyranylidene)meth yl]-6-methylbenzopyrylium perchlorate 19. 2,3-diphenyl-4-[(4'-benzopyranylidene)benzyl]-benzopyrylium perchlorate 20. 2-phenyl-4-[(4'-benzopyranylidene)benzyl]benzopyrylium perchlorate 21. 2,3-diphenyl-4-[(4'-benzopyranylidene)methyl]-6-methylbenzopyrylium perchlorate 22. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(4'-benzopyranylidene)methyl] benzopyrylium perchlorate 23. 2-styryl-3-phenyl-4-[(4'-benzopyranylidene)methyl]-6-methylbenzopyr ylium perchlorate 24. 2-p-methoxystyryl-3-phenyl-4-[(4'-benzopyranylidene)-methyl]-6-meth ylbenzopyrylium perchlorate 25. 9-[(4'-benzopyranylidene)methyl]xanthylium perchlorate 26. 2-p-methoxystyryl-4-[(4'-benzopyranylidene)methyl]-benzopyrylium perchlorate 27. 2-p-methoxystyryl-4-[(2'-p-methoxystyryl-4'-benzopyranylidene)methy l]benzopyrylium perchlorate 28. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-p-methoxystyryl-4'-benzop yranylidene)methyl]benzopyrylium perchlorate 29. 2-styryl-3-phenyl-4-[(2'-p-methoxystyryl-4'-benzopyranylidene)methy l]-6-methylbenzopyrylium perchlorate 30. 2,3-diphenyl-4-[(2'-p-methoxystyryl-4'-benzopyranylidene)-methyl]-6 -methylbenzopyrylium perchlorate 31. 2,3-diphenyl-4-[(2'-p-methoxystyryl-4'-benzopyranylidene)benzyl]-6- methylbenzopyrylium perchlorate 32. 2-phenyl-4-[(2'-p-methoxystyryl-4'-benzopyranylidene)-benzyl]benzop yrylium perchlorate 33. 9-[(2'-p-methoxystyryl-4'-benzopyranylidene)methyl]-xanthylium perchlorate 34. 2-p-methoxystyryl-4-[(4'-benzothiopyranylidene)methyl]-benzopyryliu m perchlorate 35. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(4'-benzothiopyranylidene)-me thyl]benzopyrylium perchlorate 36. 2-styryl-3-phenyl-4-[(4'-benzothiopyranylidene)methyl]-6-methylbenz opyrylium perchlorate 37. 2,3-diphenyl-4-[(4'-benzothiopyranylidene)methyl]-6-methylbenzopyry lium perchlorate 38. 2,3-diphenyl-4-[ (4'-benzothiopyranylidene)benzyl]-6-methylbenzopy rylium perchlorate 39. 2-phenyl-4-[(4'-benzothiopyranylidene)benzyl]benzopyrylium perchlorate 40. 9-[(4'-benzothiopyranylidene)methyl]xanthylium perchlorate. 41. 2-p-methoxystyryl-3-phenyl-4-[(4'-benzothiopyranylidene)-methyl]-6- methylbenzopyrylium perchlorate 42. 2-p-methoxystyryl-4-[(2'-3",4"-dimethoxystyryl-4'-benzopyranylidene )methyl]benzopyrylium perchlorate 43. 2-styryl-3-phenyl-4-[(2'-3",4"-dimethoxystyryl-4'-benzopyranylidene )methyl]-6-methylbenzopyrylium perchlorate 44. 9-[(2'-3",4"-dimethoxystyryl-4'-benzopyranylidene)-methyl]xanthyliu m perchlorate 45. 2-phenyl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranylidene) -benzyl]benzopyrylium perchlorate 46. 2,3-diphenyl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranylid ene)benzyl]-6-methylbenzopyrylium perchlorate 47. 2,3-diphenyl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranylid ene)methyl]-6-methylbenzopyrylium perchlorate 48. 2-p-methoxystyryl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyra nylidene)methyl]benzopyrylium perchlorate 49. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-.beta.-furyl(.alpha.')eth enyl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate 50. 9-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranylidene)methyl]-x anthylium perchlorate 51. 2-phenyl-4-[(2'-.alpha.-phenylstyryl-4'-benzopyranylidene)-benzyl]b enzopyrylium perchlorate 52. 2-p-methoxystyryl-4-[(2'-.alpha.-phenylstyryl-4'-benzopyranylidene) methyl]benzopyrylium perchlorate 53. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-.alpha.-phenylstyryl-4'-b enzopyranylidene)methyl]benzopyrylium perchlorate 54. 2-phenyl-4-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene )benzyl]benzopyrylium perchlorate 55. 2,3-diphenyl-4-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranyli dene)benzyl] -6-methylbenzopyrylium perchlorate 56. 2,3-diphenyl-4-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranyli dene)methyl]-6-methylbenzopyrylium perchlorate 57. 2-p-methoxystyryl-4-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyr anylidene)methyl]benzopyrylium perchlorate 58. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-.alpha.-phenyl-p-methoxys tyryl-4'-benzopyranylidene)methyl] benzopyrylium perchlorate 59. 9-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl] xanthylium perchlorate 60. 2-p-methoxystyryl-4-[(2'-.alpha.-phenyl-.beta.-furyl(.alpha.')ethen yl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate 61. 9-[(2'-.alpha.-phenyl-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranyl idene)methyl]xanthylium perchlorate 62. 2-phenyl-4-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranyl idene)benzyl]benzopyrylium perchlorate 63. 2,3-diphenyl-4-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-benzopyr anylidene)benzyl]-6-methylbenzopyrylium perchlorate 64. 2,3-diphenyl-4-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-benzopyr anylidene)methyl]-6-methylbenzopyrylium perchlorate 65. 2-p-methoxystyryl-4-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-ben zopyranylidene)methyl]benzopyrylium perchlorate 66. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-p-methoxystyryl-3'-phenyl -6'-methyl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate 67. 9-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranylidene)met hyl]xanthylium perchlorate 68. 2-phenyl-4-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl-4'-benzop yranylidene)benzyl]benzopyrylium perchlorate 69. 2,3-diphenyl-4-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl-4'-be nzopyranylidene)benzyl]-6-methylbenzopyrylium perchlorate 70. 2,3-diphenyl-4-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl-4'-be nzopyranylidene)methyl] -6-methylbenzopyrylium perchlorate 71. 2-p-methoxystyryl-4-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl- 4'-benzopyranylidene)methyl]benzopyrylium perchlorate 72. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-3",4"-dimethoxystyryl-3'- phenyl-6'-methyl-4'-benzopyranylidene)methyl]-benzopyrylium perchlorate 73. 9-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranylide ne)methyl]xanthylium perchlorate 74. 2-phenyl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-3'-phenyl-6'-methyl-4 '-benzopyranylidene)benzyl]benzopyrylium perchlorate 75. 2,3-diphenyl-4-[(2'-.beta.-furyl (.alpha.')ethenyl-3'-phenyl-6'-met hyl-4'-benzopyranylidene)benzyl]-6-methylbenzopyrylium perchlorate 76. 2,3-diphenyl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-3'-phenyl-6'-meth yl-4'-benzopyranylidene)methyl]-6-methylbenzopyrylium perchlorate 77. 2-p-methoxystyryl-4-[(2'-.beta.-furyl(.alpha.')ethenyl-3'-phenyl-6' -methyl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate 78. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-.beta.-furyl(.alpha.')eth enyl-3'-phenyl-6'-methyl-4'-benzopyranylidene)methyl]-benzopyrylium perchlorate 79. 9-[(2'-.beta.-furyl(.alpha.')ethenyl-3'-phenyl-6'-methyl-4'-benzopy ranylidene)methyl]xanthylium perchlorate 80. 2-phenyl-4-[(2'-phenyl-4'-benzothiopyranylidene)benzyl]-benzopyryli um perchlorate 81. 2,3-diphenyl-4-[(2'-phenyl-4'-benzothiopyranylidene)-benzyl]-6-meth ylbenzopyrylium perchlorate 82. 2,3-diphenyl-4-[(2'-phenyl-4'-benzothiopyranylidene)-methyl]-6-meth ylbenzopyrylium perchlorate 83. 2-p-methoxystyryl-4-[(2'-phenyl-4'-benzothiopyranylidene)methyl]ben zopyrylium perchlorate 84. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzothiopyrany lidene)methyl]benzopyrylium perchlorate 85. 2-p-methoxystyryl-3-phenyl-4-[(2'-phenyl-4'-benzothiopyranylidene)m ethyl] -6-methylbenzopyrylium perchlorate 86. 2-styryl-3-phenyl-4-[(2'-phenyl-4'-benzothiopyranylidene)methyl]-6- methylbenzopyrylium perchlorate 87. 9-[(2'-phenyl-4'-benzothiopyranylidene)methyl]xanthylium perchlorate 88. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylide ne)methyl]benzopyrylium fluoborate 89. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylide ne)methyl]benzopyrylium chloroferrate 90. 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylide ne)methyl]benzopyrylium chlorozincate 91. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-benzopyrylium perchlorate 92. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium perchlorate 93. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium fluoborate 94. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium chloroferrate 95. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium nitrate 96. 2-[(2'-styryl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate 97. 2-[(2'-styryl-4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium perchlorate 98. 2-[(4'-benzopyranylidene)methyl]benzopyrylium perchlorate 99. 2-[(4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium perchlorate 100. 2-[(2'-p-methoxystyryl-4'-benzopyranylidene)methyl]-benzopyrylium perchlorate 101. 2-[(2'-p-methoxystyryl-4'-benzopyranylidene)methyl]-3-phenylbenzopy rylium perchlorate 102. 2-[(4'-benzothiopyranylidene)methyl]benzopyrylium perchlorate 103. 2-[(4'-benzothiopyranylidene)methyl]-3-phenylbenzopyrylium perchlorate 104. 2-[(2'-3",4"-dimethoxystyryl-4'-benzopyranylidene)-methyl]benzopyry lium perchlorate 105. 2-[(2'-3",4"-dimethoxystyryl-4'-benzopyranylidene)-methyl]-3-phenyl benzopyrylium perchlorate 106. 2-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranylidene)methyl]-b enzopyrylium perchlorate 107. 2-[(2'-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranylidene)methyl]-3 -phenylbenzopyrylium perchlorate 108. 2-[(2'-.alpha.-phenylstyryl-4'-benzopyranylidene)methyl]-benzopyryl ium perchlorate 109. 2-[(2'-.alpha.-phenylstyryl-4'-benzopyranylidene)methyl]-3-phenylbe nzopyrylium perchlorate 110. 2-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl] benzopyrylium perchlorate 111. 2-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl] -3-phenylbenzopyrylium perchlorate 112. 2-[(2'-.alpha.-phenyl-.beta.-furyl(.alpha.')ethenyl-4'-benzopyranyl idene)methyl]-3-phenylbenzopyrylium perchlorate 113. 2-[(2'-p-methoxystyryl-3',6'-diphenyl-4'-benzopyranylidene)methyl]- 3-phenylbenzopyrylium perchlorate 114. 2-[(2'-3",4"-dimethoxystyryl-3',6'-diphenyl-4'-benzopyranylidene)me thyl]-3-phenylbenzopyrylium perchlorate 115. 2-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranylidene)met hyl]benzopyrylium perchlorate 116. 2-[(2'-p-methoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranylidene)met hyl]-3-phenylbenzopyrylium perchlorate 117. 2-[(2'-3",4",-dimethoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranylid ene)methyl]benzopyrylium perchlorate 118. 2-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl-4'-benzopyranylide ne)methyl]-3-phenylbenzopyrylium perchlorate 119. 2-[(2'-.beta.-furyl(.alpha.')ethenyl-3'-phenyl-6'-methyl-4'-benzopy ranylidene)methyl]benzopyrylium perchlorate 120. 2-[(2'-.beta.-furyl(.alpha.')ethenyl-3'-phenyl-6'-methyl-4'-benzopy ranylidene)methyl]-3-phenylbenzopyrylium perchlorate 121. 2-[(2'-phenyl-4'-benzothiopyranylidene)methyl]benzopyrylium perchlorate 122. 2-[(2'-phenyl-4'-benzothiopyranylidene)methyl]-3-phenylbenzopyryliu m perchlorate 123. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-4-p-methoxyphenylbenzoth iopyrylium perchlorate 124. 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-3-phenyl-4-p-methoxyphen ylbenzopyrylium perchlorate 125. 2-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl] -4-p-methoxyphenylbenzothiopyrylium perchlorate 126. 2-[(2'-.alpha.-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl] -3-phenyl-4-p-methoxyphenylbenzothiopyrylium perchlorate 127. 2-[(2'-phenyl-4'-benzothiopyranylidene)methyl]-4-p-methoxyphenylben zothiopyrylium perchlorate 128. 2-[(2'-phenyl-4'-benzothiopyranylidene)methyl]-3-phenyl-4-p-methoxy phenylbenzothiopyrylium perchlorate ______________________________________ Table 2 lists additional information on the absorption maximum in dichloroethane and melting point of the novel compounds according to the invention.

Table 2 ______________________________________ Compound Absorption Maximum Number Melting Point in dichloroethane (m.mu.) ______________________________________ 1 135.about.139 415 and 710 2 130.about.132 430 and 720 3 182.about.187 410 and 630 4 164.about.170 635 5 163.about.172 490 and 575 6 >300 575 and 660 7 162.about.169 500 and 610 8 180.about.187 490 and 670 9 157.about.160 550 and 670 10 103.about.105 610 11 120.about.126 595 12 176.about.180 430 and 700 13 122.about.126 420 and 730 14 163.about.170 420 and 650 15 160.about.164 500 and 600 16 166.about.169 495 and 710 17 135.about.140 580 18 159.about.162 555 19 179.about.181 420 and 730 20 140.about.142 415 and 730 21 165.about.172 410 and 700 22 174.about.178 500 and 600 23 176.about.179 485 24 170.about.175 505 25 >300 630 26 >300 560 27 191.about.197 560 28 201.about.203 500 and 590 29 200.about.204 660 and 710 30 185.about.189 410 and 650 31 178.about.183 430 and 690 32 181.about.188 420 and 700 33 117.about.123 550 and 650 34 185.about.189 590 35 159.about.164 495 and 600 36 185.about.188 610, 650 and 700 37 160.about.165 415 and 650 38 204.about.206 425 and 700 39 166.about.169 415 and 730 40 >300 660 41 173.about.180 555 42 175.about.181 540 and 600 43 167.about.173 660 and 710 44 161.about.164 580 and 720 45 145.about.150 415 and 720 46 188.about.190 425 and 720 47 168.about.175 670 48 171.about.176 490 and 580 49 179.about.186 600 and 720 50 171.about.175 610 and 660 51 151.about.155 480 and 740 52 171.about.176 495 and 580 53 173.about.177 590 and 700 54 140.about.147 550 and 750 55 203.about.207 420 and 680 56 138.about. 142 555 and 680 57 170.about.175 570 58 154.about.157 585 and 690 59 168.about.174 570 60 206.about.209 600 61 >300 650 62 139.about.146 550 63 202.about.204 425 and 700 64 173.about.177 530 and 690 65 190.about.194 590 66 190.about.193 500 and 600 67 192.about.195 620 68 112.about.118 570 and 760 69 190.about.192 495 70 154.about.159 650 and 700 71 177.about.182 500 and 710 72 176.about.181 590 73 195.about.199 495 and 640 74 189.about.195 550 75 184.about.187 415 and 720 76 192.about.196 640 and 700 77 >300 550 78 219.about.222 550 79 226.about.230 630 80 127.about.134 410 and 745 81 190.about.192 425 and 730 82 156.about.159 665 83 164.about.169 600 and 680 84 175.about. 178 600 and 720 85 170.about.177 550 and 700 86 157.about.166 650 and 695 87 169.about.172 635 88 137.about.140 500 and 610 89 167.about.172 500 and 610 90 160.about.163 500 and 610 91 >300 575 92 128.about.134 575 and 675 93 133.about.136 575 and 675 94 152.about.158 575 and 675 95 133.about.138 575 96 190.about.195 575 97 156.about.158 620 and 690 98 225.about.229 565 99 183.about.187 525 and 560 100 208.about.212 570 101 170.about.176 630 and 690 102 225.about.228 610 103 163.about.168 610 and 690 104 178.about.184 510 105 172.about.175 580 and 690 106 167.about.171 565 and 620 107 190.about.194 560 and 635 108 211.about.214 570 and 610 109 175.about.179 570 and 610 110 198.about.201 570 and 610 111 158.about.163 580 and 630 112 >300 600 and 645 113 185.about.188 570 and 620 114 199.about.204 600 115 211.about.215 565 and 600 116 177.about.181 570 and 610 117 205.about.207 570 118 190.about.194 590 119 237.about.241 560 120 >300 590 121 207.about.210 565 and 605 122 155.about.158 615 and 675 123 143.about.145 615 124 126.about.131 619 125 144.about.148 559 and 657 126 140.about.142 589 and 663 127 149.about.153 656 128 141.about.145 660 ______________________________________

The following description will explain a practical method for making benzopyranylidene-methylbenzopyrylium salts or benzothiopyranylidene-methylbenzopyrylium salts with reference to exemplary compounds. The details of the preparation of other compounds will be apparent to the skilled in the art from the preceding disclosure and the following illustrative examples of preparation methods of various compounds according to the invention:

(a) 2-phenyl-4-[(2'-phenyl-4'-benzopyranylidene)-benzyl]benzopyrylium perchlorate (compund number 1) ##SPC8##

5.5 Grams of 2-phenyl-4-methoxybenzopyrylium o-nitrobenzene sulfonate, which is obtained from flavone and methyl o-nitrobenzenesulfonate, and 5 grams of 2-phenyl-4-benzylbenzopyrylium perchlorate are dissolved in 150 milliliters of acetic anhydride to a solution. The solution is then refluxed for 15 minutes and poured into 900 milliliters of 10 weight percent perchloric acid. The solution is filtered to obtain a precipitate. The precipitate is dried and dissolved again in dichloroethan to a solution. For purification the solution is poured into ether. Precipitated crystals are filtered off, washed with ether and dried to obtain 4 grams (theoretical yield 53%) of green crystals having a melting point of 135.degree. to 139.degree. C.

(b) 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)meth yl]benzopyrylium perchlorate (compound number 7) ##SPC9##

5.5 grams of 2-(.alpha.-phenyl-p-methoxystyryl)-4-methylbenzopyrylium perchlorate and 5.5 grams of 2-phenyl-4-methoxybenzopyrylium o-nitrobenzene sulfonate are dissolved in 150 milliliters of acetic anhydride to a solution. The solution is then refluxed for 15 minutes and poured into 900 milliliters of 10 weight percent perchloric acid. The solution is filtered to obtain a precipitate. The precipitate is reprecipitated with dichloroethane ether. Precipitated crystals are filtered off, washed with ether and dried to obtain 5.5 grams (theoretical yield 69%) of blue crystals having a melting point of 162.degree. to 169.degree.C. In the procedure above mentioned the solution ios poured into an ether solution of BF.sub.3.O(C.sub.2 H.sub.5).sub.2 instead of 10 weight percent perchloric acid. In this case 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)meth yl]benzopyrylium fluoroborate (compound number 88) is obtained. In the procedure when the solution is poured into a 10 weight percent zinc chloride aqueous solution, 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)-met hyl]benzopyrylium chlorozincate (compound number 90) is obtained.

(c) 2-p-methoxystyryl-3-phenyl-4-[(2'-styryl-4'-benzopyranylidene)methyl]-6-me thylbenzopyrylium perchlorate (compound number 18) ##SPC10##

2-styryl-4-methoxybenzopyrylium o-nitrobenzenesulfon (melting point, 155.degree. to 157.degree. C) is obtained by a reaction of 2-styrylchromone and methyl o-nitrobenzenesulfonate in dry benzene at 50.degree. C for 24 hours. According to the same reaction as shown in procedure (a), 2-styryl-4-methoxybenzopyrylium o-nitrobenzenesulfonate reacts with 2-p-methoxystyryl-3-phenyl-4,6-dimethylbenzopyrylium perchlorate to obtain 2-p-methoxystyryl-3-phenyl-4-[(2'-styryl-4'-benzopyranylidene)methyl]-6-me thylbenzopyrylium perchlorate crystals which have a color of reddish violet in dichloroethane and have a melting point of 159.degree. to 162.degree. C. The product is obtained in 73% yield.

(d) 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(4'-benzopyranylidene)-methyl]benzop yrylium perchlorate (compound number 22) ##SPC11##

4-methoxybenzopyrylium o-nitrobenzenesulfonate reacts with 2-(.alpha.-phenyl-p-methoxystyryl)-4-methyl]benzopyrylium perchlorate to 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(4'-benzopyranylidene)methyl]-benzop yrylium perchlorate in the same procedure as the procedure (a). The crystals have a color of violet in dichloroethane and a melting point of 174.degree. to 178.degree.C. The product is obtained in 95% yield.

(e) 2-p-methoxystyryl-4-[(2'-3",4"-dimethoxystyryl-4'-benzopyranylidene)methyl ]benzopyrylium perchlorate (compound number 42) ##SPC12##

2-(3',4'-Dimethoxystyryl)-4-methoxybenzopyrylium o-nitrobenzenesulfonate (melting point 211.degree. to 213.degree.C) is obtained from a reaction of 2-(3',4'-dimethoxystyryl)chromone and methyl o-nitrobenzene sulfonate. 6.5 Grams of 2-(3',4'-dimethoxystyryl)-4-methoxybenzopyrylium o-nitrobenzenesulfonate and 4,5 grams of 2-p-methoxystyryl-4-methylbenzopyrylium perchlorate are dissolved in 150 milliliters of acetic anhydride to a solution. The solution is heated at 100.degree.C for 100 minutes. After cooling the solution is poured into 900 milliliters of 10 weight percent perchloric acid. Precipitates are filtered off and dried. For purification, reprecipitation is made using dichlorethane and ether. 3.2 Grams of product is obtained in 41% yield. The product has a color of drak violet in dichloroethane and a melting point of 175.degree. to 181.degree.C.

(f) 2-(.alpha.-phenyl-p-methoxystyryl)-4-(2'-p-methoxystyryl-3'-phenyl-6'-meth yl-4'-benzopyranylidene)methyl]-benzopyrylium perchlorate (compound number 66) ##SPC13##

2-p-Methoxystyryl-3-phenyl-4-methoxy-6-methylbenzopyrylium o-nitrobenzenesulfonate (melting point 141.degree. to 144.degree.C) is obtained from 2-p-methoxystyryl-3-phenyl-6-methylchromone and methyl o-nitrobenzenesulfonate. 2-p-methoxystyryl-3-phenyl-4-methoxy-6-methylbenzopyrylium o-nitrobenzenesulfonate reacts with 2-(.alpha.-phenyl-p-methoxystyryl)-4-methylbenzopyrylium perchlorate in the same procedure as the procedure (e). The product has a color of violet in dichloroethane and a melting point of 190.degree. to 193.degree. C.

(g) 2-p-methoxystyryl-3-phenyl-4-[(2'-phenyl-4'-benzothiopyranylidene)methyl]- 6-methyl]benzopyrylium perchlorate (compound number 85) ##SPC14##

2-phenyl-4-methoxybenzothiopyrylium o-nitrobenzenesulfonate is obtained from thioflavone and methyl o-nitrobenzenesulfonate. As the same procedure as procedure (e), the product is obtained in 62% yield. The product has a color of reddish violet in dichloroethane and a melting point of 170.degree. to 177.degree. C.

(h) 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-3-phenylbenzopyrylium perchlorate (compound number 92) ##SPC15##

5.5 grams of 2-phenyl-4-methoxybenzopyrylium o-nitrobenzenesulfonate, which is obtained from flavone and methyl o-nitrobenzenesulfonate, and 4 grams of 2-methyl-3-phenylbenzopyrylium perchlorate are dissolved in 150 milliliters of acetic anhydride to a solution. The solution is heated at 100.degree. C for 15 minutes. After cooling the solution is poured into 900 milliliters of 10 weight percent perchloric acid. Precipitated product is filtered off and dried. For purification, reprecipitation is made using dichloroethane and ether. The product has a color of blue in dichloroethane and a melting point of 128.degree. to 134.degree. C. The product yields 3 grams (theoretical yield 46%). Compound number 93 (fluoborate), compound number 94 (chloroferrate) or compound number 95 (nitrate) is obtained using either solution of borontrifluoride etherate, aqueous solution of ferric chloride or diluted nitric acid respectively instead of 10 weight percent perchloric acid.

(i) 2[(2'-4-phenyl-p-methoxystyryl-4'-benzopyranylidene)methyl]-3-phenylbenzop yrylium perchlorate (compound number 11) ##SPC16##

2-(.alpha.-Phenyl-p-methoxystyryl)-4-methoxybenzopyrylium o-nitrobenzenesulfonate, which is obtained from 2-(.alpha.-phenyl-p-methoxystyryl)chromone and methyl o-nitrobenzenesulfonate, reacts with 2-methyl-3-phenylbenzopyrylium perchlorate in the same procedure as procedure (h). The reaction product yields in 43%. The product has a color of violet in dichloroethane and a melting point of 158.degree. to 163.degree.C.

It has been discovered according to the invention the compounds listed in Table 1 are sensitizing agents which can improve the photoconductivity and the spectrum characteristics of photoconductive polymeric compounds such as poly-N-vinylcarbazole, brominated poly-N-vinylcarbazoles, polyacenaphthylene, etc. These polymers, except brominated poly-N-vinylcarbazoles, are prepared in a per se well known method. The brominated poly-N-vinylcarbazole can be prepared by the following method: To the solution of 20 grams of poly-N-vinylcarbazole in 450 milliliters of chlorobenzene, there are added 18.44 grams of N-bromosuccinimide and 0.173 grams of benzoyl peroxide. The mixture is heated at 80.degree.C for 2 hours while being stirred thoroughly and is poured into methanol to obtain a white polymer. The polymer is dissolved in chlorobenzene and again poured into methanol for purification. The pure polymer thus obtained as a precipitate exhibits upon elementary analysis a halogen content of 29.87 weight percent which approximates the value calculated, i.e. 29.44 weight percent of the monobromosubstituted product from poly-N-vinylcarbazole. This indicates that the polymer obtained is a monobromosubstituted product. The degree of bromination varies from 50 mole percent to 200 mole percent according to reaction conditions.

The novel sensitizer comprising at least one compound from the group listed in Table 1 is dissolved in a suitable solvent, such as dichloroethane, methylene chloride, chloroform, or a combination thereof, and is added to the solution of the photoconductive polymer described above. The preferable amount of the sensitizer added is from 0.01 to 3.0 weight parts in connection with 100 weight parts of the photoconductive polymer. Advantageously, the amount thereof is from 0.1 to 2.0 weight parts in connection with 100 weight parts of the photoconductive polymer.

For the preparation of the photoconductive insulating layer, a said solution of the photoconductive polymer and the sensitizer in a suitable solvent is applied to the electroconductive support in per se usual manner, for example, by spraying, by means of bladed coating, by means of whirler coating, etc., and then dried so as to produce a homogeneous photoconductive insulating layer on the electroconductive support. Operable solvents are benzene, toluene, chlorobenzene, dioxane, methylene chloride, dichloroethane and combinations thereof. Said solution may be incorporated with suitable plasticizers and/or organic colloids for improving the flexibility and strength of the photoconductive polymer. Operable plasticizers are as follows: chlorinated diphenyl, dimethyl phthalate, diethyl phthalate and octyl phthalate. Operable organic colloids are as follows: natural and synthetic resins, e.g. phenol resin, phenol resin modified with resin, polyvinyl acetal, polyvinyl butyral, polyvinyl cinnamate, polycarbonate resin. Operable materials for electroconductive supports may be made of any materials which satisfy the requirement of the electrophotographic art, e.g. metal plate or glass plate having NESA coating, plate or foil made of electrically conductive resin or coated with evaporated thin metal layer. If paper is to be used as a support for the photoconductive layer, pretreatment of the paper against penetration of the coating solution in advisable. The transparent support can produce a transparent electrophotographic plate, foil or film. After an electrostatic charge has been applied, i.e. after the layer has been charged positively or negatively by means of a corona discharge, the layer becomes light sensitive.

The reproduction of images by the electrophotographic method is carried out as follows: when the photoconductive layer has been charged by means of a corona discharge apparatus, the support with the sensitized layer is exposed to light under a master and is then dusted over in a per se known manner with a resin powder colored with carbon black. The image that now becomes visible can easily be wiped off. It can also be fixed by heating at about 120.degree.C. From positive masters, positive images characterized by good contrast the producted.

This invention is still further illustrated with reference to the following illustrative examples.

EXAMPLE 1

1 Gram of polyacenaphthylene and 0.6 gram of, as a plasticiser, chlorinated diphenyl (commercially available as "Kanechlor"), are dissolved in 8 milliliters of chlorobenzene. To the solution are added 0.5 milliliters of dichloroethane containing 0.006 gram of a sensitizer corresponding to compound number listed in Table 1. The solution is applied to an aluminum plate by means of whirler coating and is dried to form a layer of 7.mu. in thickness. After said aluminum plate provided with the layer is charged negatively by means of corona discharge with a charging device maintained at approximately 6000 volts in the dark, it is placed under a positive master and is exposed to a 100W tungsten lamp at an illumination of 50 luxes, and the said plate is powdered over with a developer in a per se known manner. This developer consists of toner and carrier. The toner consists of low melting point polystyrene, colophony and carbon black. The toner is mixed with a carrier substance such that the toner becomes triboelectrically charged with a charge opposite to that produced on the plate. A positive image is produced and is fixed by slight heating. In Table 2, there are shown the optimum amounts of exposure in lux-second units.

Table 2 ______________________________________ Compound Number Optimum Exposure (lux.sec) ______________________________________ none 200000 5 320 7 300 9 75 15 180 16 110 18 65 33 135 35 480 41 105 42 320 51 380 52 140 53 290 54 140 58 130 60 175 65 140 71 180 92 70 97 150 103 100 105 120 109 130 110 180 111 70 112 170 113 120 116 115 ______________________________________

EXAMPLE 2

1 Gram of poly-N-vinylcarbazole, chlorinated diphenyl (commercially available as "Kanechlor") and 0.006 gram of a sensitizer, coresponding to compound number listed in Table 1, in 10 milliliters of dichloroethane to a solution. The solution is applied to an aluminum plate by means of blade coating and is dried to form a layer of 10.mu. in thickness. An electrophotographic image in the same way as that described in Example 1. In Table 3, there are shown the optimum amounts of exposure in lux-second units to produced exactly the original images.

Table 3 ______________________________________ Compound Number Optimum Exposure (lux.sec) ______________________________________ none 20000 1 50 2 220 3 60 4 70 5 22 6 44 7 26 8 62 9 44 10 48 11 160 12 220 13 90 14 75 15 28 16 36 17 115 18 22 23 180 26 110 27 44 28 36 29 40 30 60 32 120 33 36 34 50 35 30 36 46 37 90 41 52 42 44 43 48 45 75 47 58 48 34 49 35 50 70 51 30 53 26 54 28 56 28 57 20 58 24 59 36 60 44 61 44 62 100 64 54 65 44 66 22 67 74 70 56 71 20 72 22 76 60 78 38 80 46 82 50 83 24 84 19 85 17 86 54 87 42 88 25 89 28 90 30 91 140 92 18 93 20 34 23 95 40 96 66 29 24 98 230 99 460 100 50 101 36 102 115 103 36 104 68 105 19 106 120 107 58 108 76 109 46 110 36 111 20 112 42 113 48 114 54 115 54 116 52 117 64 118 50 119 135 120 90 121 30 122 28 ______________________________________

It is clear from Table 3 that the novel sensitizers improve the photoconductivity of poly-N-vinylcarbazole.

EXAMPLE 3

1 Gram of brominated poly-N-vinylcarbazole (monobromo-substituted product), 0.5 gram of polycarbonate resin (commercially available as "Panlite-C"), 0.3 gram of chlorinated diphenyl (commercially available as "Kanechlor") and 0.002 gram of sensitizer listed in Table 1 are dissolved in a mixed-solvent of 8 milliliters of chlorobenzene and 2 milliliters of dichloroethane. This solution is applied to an aluminum plate by means of a blade coating and dried to form a layer of 14.mu. in thickness. On this support, electrophotographic images are produced in the same way as that described in Example 1. Table 4 shows the optimum amounts of exposure in lux-second units to reproduce exactly the original images.

Table 4 ______________________________________ Compound Number Optimum Exposure (lux.sec) ______________________________________ none 80000 1 75 2 280 3 67 4 44 5 20 6 26 7 18 8 30 9 22 10 40 11 120 12 400 13 110 14 75 15 25 16 28 17 135 18 23 19 410 20 340 21 180 22 40 23 130 24 60 25 300 26 100 27 52 28 52 29 48 30 110 31 320 32 270 33 27 34 30 35 26 37 52 38 440 39 110 40 125 41 22 42 28 43 32 44 75 45 105 46 170 47 42 48 32 49 35 50 50 51 48 52 20 53 19 54 42 55 230 56 26 57 22 58 24 59 23 60 26 61 36 62 130 63 190 64 44 65 26 66 20 67 46 68 75 69 115 70 42 71 18 72 20 73 48 74 110 75 115 76 70 77 44 78 35 79 75 80 50 81 145 82 35 83 20 84 19 85 17 86 34 87 34 88 20 89 20 90 25 91 100 92 15 93 17 94 16 95 40 96 52 97 26 98 180 99 140 100 46 101 36 102 58 103 20 104 34 105 21 106 80 107 44 108 40 109 23 110 26 111 17 112 26 113 28 114 40 115 44 116 28 117 44 118 36 119 105 120 52 121 26 122 21 123 15 124 25 125 17 126 14 127 11 128 13 ______________________________________

It is clear from Table 4 and FIGS. 1 to 9 that the novel sensitizers improve the photoconductivity and the spectrum characteristics of brominated poly-N-vinylcarbazole.

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

Claims

1. An electrophotographic material comprising a conductive support layer and photoconductive insulating layer, the latter comprising a combination of a photoconductive polymeric compound and a sensitizing amount of a sensitizer having the following formula: ##SPC17##

B represents a radical selected from the group consisting of ##SPC18## ##SPC19##

R.sub.1 is hydrogen, phenyl or an ethenyl radical selected from the group consisting of styryl, p-methoxystyryl, 3,4-dimethoxy-styryl,.alpha.-phenylstyryl,.alpha.-phenyl-p-methoxystyryl,.beta.-furyl(.alpha.')ethenyl and.alpha.-phenyl-.beta.-furyl(.alpha.') ethenyl;

R.sub.2 is hydrogen or phenyl;

R.sub.3 is hydrogen, methyl or phenyl;

R.sub.4 is hydrogen or phenyl;

R.sub.5 is hydrogen, phenyl or an ethenyl radical selected from the group consisting of styryl, p-methoxystyryl, 3,4-dimethoxy-styryl,.alpha.-phenyl-p-methoxystyryl,.beta.-furyl(.alpha.')ethenyl and.alpha.-phenyl-.beta.-furyl(.alpha.')ethenyl;

R.sub.6 is hydrogen or phenyl;

R.sub.7 is hydrogen or phenyl;.Iadd.

R.sub.8 is hydrogen or phenyl;

R.sub.9 is hydrogen or p-methoxyphenyl;.Iaddend.

the anion is an anionic function selected from the group consisting of perchlorate, fluoroborate, chloroferrate, chlorozincate and nitrate; and

X is oxygen or a sulfur atom;

said photoconductive polymeric compound comprising at least one compound selected from the group consisting of poly-N-vinylcarbazole, brominated

2. An electrophotographic material according to claim 1, wherein said sensitizer comprises at least one compound selected from the group consisting of 2-(.alpha.-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)meth yl]benzopyrylium perchlorate, 2-p-methoxystyryl-4-[(2'-3",4"-dimethoxystyryl-3'-phenyl-6'-methyl-4'-benz opyranylidene)methyl]benzopyrylium perchlorate, 2-[(2'-phenyl-4'-benzopyranylidene) methyl]-3-phenyl benzopyrylium fluoroborate, 2-[(2'-phenyl-4'-benzopyranylidene)methyl]-4-p-methoxyphenyl benzothiopyrylium perchlorate, and 2-[(2'-phenyl-4'-benzothiopyryanylidene)methyl]-4-p-methoxyphenyl

3. An electrophotographic material according to claim 1, wherein said combination comprises 100 weight parts of photoconductive polymeric compound and 0.01 to 3.0 weight parts of sensitizer.