Electrophotographic material containing sensitizers

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-(α-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)-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. 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-methylbenzopyrylium 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'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene)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]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. 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'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene)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. 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 1 is hydrogen, phenyl or an ethenyl or an ethenyl radical selected from the group consisting of styryl,p-methoxystyryl, 3,4-dimethoxystyryl, α-phenylstyryl, α-phenyl-p-methoxystyryl, β-furyl(α')ethenyl and α-phenyl-β-furyl(α')-ethenyl;

R 2 is hydrogen or phenyl;

R 3 is hydrogen, methyl or phenyl;

R 4 is hydrogen or phenyl;

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

R 6 is hydrogen or phenyl;

R 7 is hydrogen, methyl or phenyl;

R 8 is hydrogen or phenyl; .Iadd.

R 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.

______________________________________

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-β-furyl(α')ethenyl-4-[(2'-phenyl-4'-benzopyranylidene-

methyl]benzopyrylium perchlorate

7. 2-(α-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-β-furyl(α')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-(α-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-(α-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-(α-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-(α-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'-β-furyl(α')ethenyl-4'-benzopyranylidene)

-benzyl]benzopyrylium perchlorate

46. 2,3-diphenyl-4-[(2'-β-furyl(α')ethenyl-4'-benzopyranylid

ene)benzyl]-6-methylbenzopyrylium perchlorate

47. 2,3-diphenyl-4-[(2'-β-furyl(α')ethenyl-4'-benzopyranylid

ene)methyl]-6-methylbenzopyrylium perchlorate

48. 2-p-methoxystyryl-4-[(2'-β-furyl(α')ethenyl-4'-benzopyra

nylidene)methyl]benzopyrylium perchlorate

49. 2-(α-phenyl-p-methoxystyryl)-4-[(2'-β-furyl(α')eth

enyl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate

50. 9-[(2'-β-furyl(α')ethenyl-4'-benzopyranylidene)methyl]-x

anthylium perchlorate

51. 2-phenyl-4-[(2'-α-phenylstyryl-4'-benzopyranylidene)-benzyl]b

enzopyrylium perchlorate

52. 2-p-methoxystyryl-4-[(2'-α-phenylstyryl-4'-benzopyranylidene)

methyl]benzopyrylium perchlorate

53. 2-(α-phenyl-p-methoxystyryl)-4-[(2'-α-phenylstyryl-4'-b

enzopyranylidene)methyl]benzopyrylium perchlorate

54. 2-phenyl-4-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene

)benzyl]benzopyrylium perchlorate

55. 2,3-diphenyl-4-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyranyli

dene)benzyl] -6-methylbenzopyrylium perchlorate

56. 2,3-diphenyl-4-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyranyli

dene)methyl]-6-methylbenzopyrylium perchlorate

57. 2-p-methoxystyryl-4-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyr

anylidene)methyl]benzopyrylium perchlorate

58. 2-(α-phenyl-p-methoxystyryl)-4-[(2'-α-phenyl-p-methoxys

tyryl-4'-benzopyranylidene)methyl] benzopyrylium perchlorate

59. 9-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl]

xanthylium perchlorate

60. 2-p-methoxystyryl-4-[(2'-α-phenyl-β-furyl(α')ethen

yl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate

61. 9-[(2'-α-phenyl-β-furyl(α')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-(α-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-(α-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'-β-furyl(α')ethenyl-3'-phenyl-6'-methyl-4

'-benzopyranylidene)benzyl]benzopyrylium perchlorate

75. 2,3-diphenyl-4-[(2'-β-furyl (α')ethenyl-3'-phenyl-6'-met

hyl-4'-benzopyranylidene)benzyl]-6-methylbenzopyrylium

perchlorate

76. 2,3-diphenyl-4-[(2'-β-furyl(α')ethenyl-3'-phenyl-6'-meth

yl-4'-benzopyranylidene)methyl]-6-methylbenzopyrylium perchlorate

77. 2-p-methoxystyryl-4-[(2'-β-furyl(α')ethenyl-3'-phenyl-6'

-methyl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate

78. 2-(α-phenyl-p-methoxystyryl)-4-[(2'-β-furyl(α')eth

enyl-3'-phenyl-6'-methyl-4'-benzopyranylidene)methyl]-benzopyrylium

perchlorate

79. 9-[(2'-β-furyl(α')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-(α-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-(α-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylide

ne)methyl]benzopyrylium fluoborate

89. 2-(α-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylide

ne)methyl]benzopyrylium chloroferrate

90. 2-(α-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'-β-furyl(α')ethenyl-4'-benzopyranylidene)methyl]-b

enzopyrylium perchlorate

107. 2-[(2'-β-furyl(α')ethenyl-4'-benzopyranylidene)methyl]-3

-phenylbenzopyrylium perchlorate

108. 2-[(2'-α-phenylstyryl-4'-benzopyranylidene)methyl]-benzopyryl

ium perchlorate

109. 2-[(2'-α-phenylstyryl-4'-benzopyranylidene)methyl]-3-phenylbe

nzopyrylium perchlorate

110. 2-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl]

benzopyrylium perchlorate

111. 2-[(2'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl]

-3-phenylbenzopyrylium perchlorate

112. 2-[(2'-α-phenyl-β-furyl(α')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'-β-furyl(α')ethenyl-3'-phenyl-6'-methyl-4'-benzopy

ranylidene)methyl]benzopyrylium perchlorate

120. 2-[(2'-β-furyl(α')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'-α-phenyl-p-methoxystyryl-4'-benzopyranylidene)-methyl]

-4-p-methoxyphenylbenzothiopyrylium perchlorate

126. 2-[(2'-α-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

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Table 2 lists additional information on the absorption maximum in

dichloroethane and melting point of the novel compounds according to the

invention.

______________________________________

Compound Absorption Maximum

Number Melting Point

in dichloroethane (mμ)

______________________________________

1 135˜139

415 and 710

2 130˜132

430 and 720

3 182˜187

410 and 630

4 164˜170

635

5 163˜172

490 and 575

6 >300 575 and 660

7 162˜169

500 and 610

8 180˜187

490 and 670

9 157˜160

550 and 670

10 103˜105

610

11 120˜126

595

12 176˜180

430 and 700

13 122˜126

420 and 730

14 163˜170

420 and 650

15 160˜164

500 and 600

16 166˜169

495 and 710

17 135˜140

580

18 159˜162

555

19 179˜181

420 and 730

20 140˜142

415 and 730

21 165˜172

410 and 700

22 174˜178

500 and 600

23 176˜179

485

24 170˜175

505

25 >300 630

26 >300 560

27 191˜197

560

28 201˜203

500 and 590

29 200˜204

660 and 710

30 185˜189

410 and 650

31 178˜183

430 and 690

32 181˜188

420 and 700

33 117˜123

550 and 650

34 185˜189

590

35 159˜164

495 and 600

36 185˜188

610, 650 and 700

37 160˜165

415 and 650

38 204˜206

425 and 700

39 166˜169

415 and 730

40 >300 660

41 173˜180

555

42 175˜181

540 and 600

43 167˜173

660 and 710

44 161˜164

580 and 720

45 145˜150

415 and 720

46 188˜190

425 and 720

47 168˜175

670

48 171˜176

490 and 580

49 179˜186

600 and 720

50 171˜175

610 and 660

51 151˜155

480 and 740

52 171˜176

495 and 580

53 173˜177

590 and 700

54 140˜147

550 and 750

55 203˜207

420 and 680

56 138˜ 142

555 and 680

57 170˜175

570

58 154˜157

585 and 690

59 168˜174

570

60 206˜209

600

61 >300 650

62 139˜146

550

63 202˜204

425 and 700

64 173˜177

530 and 690

65 190˜194

590

66 190˜193

500 and 600

67 192˜195

620

68 112˜118

570 and 760

69 190˜192

495

70 154˜159

650 and 700

71 177˜182

500 and 710

72 176˜181

590

73 195˜199

495 and 640

74 189˜195

550

75 184˜187

415 and 720

76 192˜196

640 and 700

77 >300 550

78 219˜222

550

79 226˜230

630

80 127˜134

410 and 745

81 190˜192

425 and 730

82 156˜159

665

83 164˜169

600 and 680

84 175˜ 178

600 and 720

85 170˜177

550 and 700

86 157˜166

650 and 695

87 169˜172

635

88 137˜140

500 and 610

89 167˜172

500 and 610

90 160˜163

500 and 610

91 >300 575

92 128˜134

575 and 675

93 133˜136

575 and 675

94 152˜158

575 and 675

95 133˜138

575

96 190˜195

575

97 156˜158

620 and 690

98 225˜229

565

99 183˜187

525 and 560

100 208˜212

570

101 170˜176

630 and 690

102 225˜228

610

103 163˜168

610 and 690

104 178˜184

510

105 172˜175

580 and 690

106 167˜171

565 and 620

107 190˜194

560 and 635

108 211˜214

570 and 610

109 175˜179

570 and 610

110 198˜201

570 and 610

111 158˜163

580 and 630

112 >300 600 and 645

113 185˜188

570 and 620

114 199˜204

600

115 211˜215

565 and 600

116 177˜181

570 and 610

117 205˜207

570

118 190˜194

590

119 237˜241

560

120 >300 590

121 207˜210

565 and 605

122 155˜158

615 and 675

123 143˜145

615

124 126˜131

619

125 144˜148

559 and 657

126 140˜142

589 and 663

127 149˜153

656

128 141˜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° to 139° C.

(b) 2-(α-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)methyl]benzopyrylium perchlorate (compound number 7) ##SPC9##

5.5 grams of 2-(α-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° to 169°C. In the procedure above mentioned the solution ios poured into an ether solution of BF 3 .O(C 2 H 5 ) 2 instead of 10 weight percent perchloric acid. In this case 2-(α-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)methyl]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-(α-phenyl-p-methoxystyryl)-4-[(2'-phenyl-4'-benzopyranylidene)-methyl]benzopyrylium chlorozincate (compound number 90) is obtained.

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

2-styryl-4-methoxybenzopyrylium o-nitrobenzenesulfon (melting point, 155° to 157° C) is obtained by a reaction of 2-styrylchromone and methyl o-nitrobenzenesulfonate in dry benzene at 50° 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-methylbenzopyrylium perchlorate crystals which have a color of reddish violet in dichloroethane and have a melting point of 159° to 162° C. The product is obtained in 73% yield.

(d) 2-(α-phenyl-p-methoxystyryl)-4-[(4'-benzopyranylidene)-methyl]benzopyrylium perchlorate (compound number 22) ##SPC11##

4-methoxybenzopyrylium o-nitrobenzenesulfonate reacts with 2-(α-phenyl-p-methoxystyryl)-4-methyl]benzopyrylium perchlorate to 2-(α-phenyl-p-methoxystyryl)-4-[(4'-benzopyranylidene)methyl]-benzopyrylium perchlorate in the same procedure as the procedure (a). The crystals have a color of violet in dichloroethane and a melting point of 174° to 178°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° to 213°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°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° to 181°C.

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

2-p-Methoxystyryl-3-phenyl-4-methoxy-6-methylbenzopyrylium o-nitrobenzenesulfonate (melting point 141° to 144°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-(α-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° to 193° 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° to 177° 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° 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° to 134° 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-phenylbenzopyrylium perchlorate (compound number 11) ##SPC16##

2-(α-Phenyl-p-methoxystyryl)-4-methoxybenzopyrylium o-nitrobenzenesulfonate, which is obtained from 2-(α-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° to 163°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°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°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.