US3871883A - Electrophotographic photoconductive layer comprising an organic photoconductor and a dicyanomethylene-indenothiophene sensitizer - Google Patents

Electrophotographic photoconductive layer comprising an organic photoconductor and a dicyanomethylene-indenothiophene sensitizer Download PDF

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US3871883A
US3871883A US425967A US42596773A US3871883A US 3871883 A US3871883 A US 3871883A US 425967 A US425967 A US 425967A US 42596773 A US42596773 A US 42596773A US 3871883 A US3871883 A US 3871883A
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indeno
dicyanomethylene
thiophene
photoconductive layer
photoconductive
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Mitsuru Hashimoto
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Ricoh Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D333/00—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom
    • C07D333/02—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings
    • C07D333/04—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom
    • C07D333/06—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom not condensed with other rings not substituted on the ring sulphur atom with only hydrogen atoms, hydrocarbon or substituted hydrocarbon radicals, directly attached to the ring carbon atoms
    • C07D333/24—Radicals substituted by carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D333/00—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom
    • C07D333/50—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom condensed with carbocyclic rings or ring systems
    • C07D333/78—Heterocyclic compounds containing five-membered rings having one sulfur atom as the only ring hetero atom condensed with carbocyclic rings or ring systems condensed with rings other than six-membered or with ring systems containing such rings
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G5/00—Recording members for original recording by exposure, e.g. to light, to heat, to electrons; Manufacture thereof; Selection of materials therefor
    • G03G5/02—Charge-receiving layers
    • G03G5/04—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor
    • G03G5/06—Photoconductive layers; Charge-generation layers or charge-transporting layers; Additives therefor; Binders therefor characterised by the photoconductive material being organic
    • G03G5/0622—Heterocyclic compounds
    • G03G5/0624—Heterocyclic compounds containing one hetero ring
    • G03G5/0627—Heterocyclic compounds containing one hetero ring being five-membered
    • G03G5/0629—Heterocyclic compounds containing one hetero ring being five-membered containing one hetero atom

Definitions

  • ABSTRACT Electrophotographic light-sensitive materials having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive compound (monomer or polymer) and 4-dicyanomethylene-4H-indeno[1,2- blthiophene or 8-dicyanomethylene-8H-indeno[2,1- blthiophene or their derivatives as sensitizers, and processes for preparing such compounds from 4H- indeno[1,2-b1thiophene-4-0ne or 8H-indeno[2,lblthiophen-v8-one or their derivatives and malonitrile.
  • Electrophotographic light-sensitive materials comprise an electroconductive support with a photocon-.
  • the principle of an electrophotographic process is that an electrostatic latent image is produced by image-wise exposure of a charged photoconductive layer and the image is then developed by a developer or toner (in liquid or powder form) which is electrically precipitated on the latent image to form a visible image.
  • inorganic photoconductors such as photoconductive zinc oxide or selenium are used.
  • organic photoconductive compound e.g., a photo conductive polymer such as poly-N-vinylcarbazole in place of the inorganic photoconductors has been proposed.
  • a photo conductive polymer such as poly-N-vinylcarbazole
  • dyestuff sensitizers are added to the organic photoconductive compounds.
  • Such dyestuffs as have been previously employed are generally not stable and bleach out quickly so that the organic photoconductive compounds lose their sensitivity in the visible region.
  • electrophotographic light-sensitive materials prepared utilizing organic photoconductive compounds containing dyestuff sensitizers are of limited practical use.
  • the present invention relates to electrophotographic light-sensitive materials having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive compound such as a photoconductive monomer or polymer and 4-dicyanomethylene-4H- indcnol l.2-b ⁇ thiophene or S-diCyanomethyIene-SH- indcnol 2,l-h Ithiophcne or their derivatives as a sensitixcr. and a process or preparing such compounds and their derivatives.
  • an organic photoconductive compound such as a photoconductive monomer or polymer and 4-dicyanomethylene-4H- indcnol l.2-b ⁇ thiophene or S-diCyanomethyIene-SH- indcnol 2,l-h Ithiophcne or their derivatives as a sensitixcr.
  • electrophotographic light-sensitive matcriuls comprise an electroconductive support and a photoconductive layer formed on the support.
  • the electrophotographic light-sensitive materials of the present invention are characterized in that the photoconductive layer comprises an organic photoconductive compound sensitized with 4-dicyanomethylenesuch 2 4l-l-indeno[l,2-b]thiophene or 8-dicyanomethylene- 8l-l-indeno[2,l-b]thiophene and their derivatives having the following general formulas. These compounds are used as sensitizers for the organic photoconductive compound.
  • R R R R R and R are hydrogen or nitro groups.
  • the electrophotographic light-sensitive materials of the present invention may be prepared by forming a photoconductive layer on an electroconductive support, the photoconductive layer comprising any of a variety or organic photoconductive monomers such as N- vinylcarbazole or organic photoconductive polymers as poly-N-vinylcarbazole and 4- dicyanomethylene-4H-indeno[1,2-b]thiophene or 8- dicyanomethylene-8H-indeno[2, l -b]thiophene or their derivatives as indicated above.
  • 4-decyanomethylene- 4H-indeno[l,2-b]thiophene or 8-dicyanomethylene 8H-indeno[2,l-b]thiophene or their derivatives are utilized in an amount of from 0.01 to 1.2 mole per mole of organic photoconductive monomer or per monomeric unit of the organic photoconductive polymer (1 mole of the organic photoconductive polymer is represented by monomeric unit of the polymer).
  • Preferred organic photoconductive polymers include poly-N-vinylcarbazole, chlorinated or brominated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylnaphthalene, polyvinylanthracene, poly-9- vinylfluorene, poly-l-arylimidazole, bromopyreneformaldehyde resin and poly-p-phenylene-l ,3 ,4- oxadiazole.
  • Electrophotographic light-sensitive materials in accordance with the present invention can be produced, for example, as follows:
  • the material obtained above was divided into two 5 parts.
  • the photoconductive layer was negatively or positively charged by a corona discharge of about 6kV or +6kV for 20 seconds to obtain a surface electric potential Vdo and then subjected to dark decay for 20 seconds to obtain a surface residual potential Vpo.
  • Polyester tungsten fllafnent Whose 1lll1mma ne at the resin, novolac resin or acrylic resin may, if desired, be faee of e hght'sensltlve layer was adlusted to be 20 added to this solution.
  • This light-sensitive solution was applied as a coat on 8-dicyanomethylene-8H compound.
  • an aluminium layer on a polyester resin film (thickness: 75 t), using a doctor blade set at a 200 u gap, and then EXAMPLES 2 8 dried in a desicator having silica gel to evaporate a sol- Electrophotographic light-sensitive materials (No. 2 vent, and further dried at a temperature of 60C for No. 8) of the present invention were obtained by reabout 10 minutes and at a temperature of 120C for 40 peating the same procedure as that of Example 1 exabout 2 minutes.
  • Chlorine is contained in a proportion of one chlorine atom per monomeric unit of poly-N-vinyl carbazole.
  • Bromine is contained in a proportion of one bromine atom per two monomeric units of poly-N-vinyl-carbazole.
  • Vpo, E and E of the light-sensitive materials No. 2 No. 8 were measured by repeating the same procedure as that of Example 1. The values obtained are shown in the Table 3 below.
  • Vpo, E and E similar to those as shown in the Tables 1 and 3 can be obtained by using 4-dicyanomethylene-4H-indeno [1,2-b1thiophene or its derivatives as shown in Formulas 1 1V in place of the above-mentioned two 4- dicyanomethy1ene-4H-indeno-[ l ,2-b]thiophene derivatives in amount of from 0.01 to 1 mole per monomeric unit of poly-N-vinylcarbazole, chlorinated or brominated poly-N-vinylcarbazole, or l-bromopyrene formaldehyde resin.
  • Electrophotographic light-sensitive materials having sensitivity to visible light can be produced with an organic photoconductive compound having no sensitivity to visible light by adding 4-dicyanomethy1ene-4H- indeno[l,2-b]thiophene or 8-dicyanomethylene-8H- indeno[2,l-b] thiophene or their derivatives to said organic photoconductive compounds.
  • Such 4-dicyanomethylene-4H-indeno[ l ,2- b]thiophene and its derivatives can be prepared by the process as described below.
  • reaction as shown above is carried out in the presence of piperidine in a solution of tetrahydrofuran.
  • novel compounds of formula 6 of the present invention as shown above is most useful as a sensitizer for organic photoconductive compounds such as poly-N- vinylcarbazole.
  • S-diCyanomethylene-SH compounds are also novel. They are prepared by the reaction of malononitrile on the corresponding 81-1,- indeno[2,1-b]thiophene-8-ones as illustrated above. The starting materials are prepared by the procedures described in:
  • An electrophotographic light-sensitive material having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive monomer or an organic photoconductive polymer, and a sensitizing compound of the formula;
  • NC -c CN wherein R R R R R and R are hydrogen or nitro groups wherein the sensitizing compound is present in an amount of from about 0.01 to about 1.2 mole per mole of the organic photoconductive monomer or per monomeric unit of the organic photoconductive polymer.

Abstract

Electrophotographic light-sensitive materials having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive compound (monomer or polymer) and 4-dicyanomethylene-4Hindeno(1,2-b)thiophene or 8-dicyanomethylene-8H-indeno(2,1b)thiophene or their derivatives as sensitizers, and processes for preparing such compounds from 4H-indeno(1,2-b)thiophene-4-one or 8H-indeno(2,1-b)thiophen-8-one or their derivatives and malonitrile.

Description

United States Patent 1191 Hashimoto [75] Inventor: Mitsuru Hashimoto, Tokyo, Japan [73] Assignee: Kabushiki Kaisha Ricoh, Tokyo,
Japan 22 Filed: Dec. 19, 1973 21 Appl. No.: 425,967
[30] Foreign Application Priority Data Dec 28, 1972 Japan 48-1944 Dec. 28, 1972 Japan 48-1945 [52] US. Cl. 96/l.5, 96/1.6, 260/329 F,
260/3322 R [51] Int. Cl G03g 5/06 [58} Field of Search 9 6/I.5, 1.6
l 56] References Cited UNITED STATES PATENTS 2,980,535 4/1961. Schroeter. ..l 96/1.5 X 3,244,516 4/1966, Neugebauer ct 3,252,794 5/1966 Schnum ct a1. 96/15 3,301,676 l/1967 Tomanek 96/].5 3,307,940 3/1967 Shattuck et a1 96/1.5 3.485625 12/1969 Fox 96/l.5
[451 Mar. 18, 1975 3,583,869 6/1971 Tubuko 96/15 3,677,752 7/1972 Looker et al. 96/l.5 X 3,752,668 8/1973 Baltazzi 96/15 3,764,317 10/1973 Depoorter et a1. 96/].6 X 3,765,882 10/1973 3,796,572 3/1974 Hashimoto 96/1.5
OTHER PUBLICATIONS Wagner et al., A Study of the Relation of Electron Affinity to the Photoconductivity of Doped PolyN-Vinylcarbazole Films: A New Method of Analyzing the Photoresponse, Photographic Science and,
Engineering, Vol. 14, No. 3, May-June, 1970, pp.
Primary E.\-aminerNorman G. Torchin Assistant Examiner-John R. Miller Attorney, Agent, or FirmCooper, Dunham, Clark, Griffin & Moran [57] ABSTRACT Electrophotographic light-sensitive materials having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive compound (monomer or polymer) and 4-dicyanomethylene-4H-indeno[1,2- blthiophene or 8-dicyanomethylene-8H-indeno[2,1- blthiophene or their derivatives as sensitizers, and processes for preparing such compounds from 4H- indeno[1,2-b1thiophene-4-0ne or 8H-indeno[2,lblthiophen-v8-one or their derivatives and malonitrile.
5 Claims, No Drawings 1 ELECTROPIIOTOGRAPHIC PHOTOCONDUCTIVE LAYER COMPRISING AN ORGANIC PHOTOCONDUCTOR AND A DICYANOMETHYLENE-INDENOTHIOPHENE SENSITIZER RELATED APPLlCATION US. Pat. application Ser. No. 416,792, filed Nov. 19, 1973, describes and claims the corresponding indenothiophenones which are starting materials for the compounds of this invention.
BACKGROUND OF THE INVENTION:
Electrophotographic light-sensitive materials comprise an electroconductive support with a photocon-.
ductive layer formed thereon. The principle of an electrophotographic process is that an electrostatic latent image is produced by image-wise exposure of a charged photoconductive layer and the image is then developed by a developer or toner (in liquid or powder form) which is electrically precipitated on the latent image to form a visible image. conventionally, for forming the photoconductive layer, inorganic photoconductors such as photoconductive zinc oxide or selenium are used. Recently, the use of an organic photoconductive compound, e.g., a photo conductive polymer such as poly-N-vinylcarbazole in place of the inorganic photoconductors has been proposed. Amongst the advantages of organic photoconductive compounds are transparency and mechanical flexibility. Additionally, they are easy to form into photoconductive layers. On the other hand, they absorb light in the ultraviolet region of the spectrum, but are not sensitive to visible light. To overcome this disadvantage, i.e., to shift their absorption into the visible region of the spectrum, dyestuff sensitizers are added to the organic photoconductive compounds. Such dyestuffs as have been previously employed are generally not stable and bleach out quickly so that the organic photoconductive compounds lose their sensitivity in the visible region. As a result, electrophotographic light-sensitive materials prepared utilizing organic photoconductive compounds containing dyestuff sensitizers are of limited practical use.
It is, therefore, an object of the present invention to provide stable sensitizers and improved electrophotographic light-sensitive materials containing such stable sensitizers.
SUMMARY OF THE INVENTION The present invention relates to electrophotographic light-sensitive materials having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive compound such as a photoconductive monomer or polymer and 4-dicyanomethylene-4H- indcnol l.2-b}thiophene or S-diCyanomethyIene-SH- indcnol 2,l-h Ithiophcne or their derivatives as a sensitixcr. and a process or preparing such compounds and their derivatives.
In general, electrophotographic light-sensitive matcriuls comprise an electroconductive support and a photoconductive layer formed on the support.
The electrophotographic light-sensitive materials of the present invention are characterized in that the photoconductive layer comprises an organic photoconductive compound sensitized with 4-dicyanomethylenesuch 2 4l-l-indeno[l,2-b]thiophene or 8-dicyanomethylene- 8l-l-indeno[2,l-b]thiophene and their derivatives having the following general formulas. These compounds are used as sensitizers for the organic photoconductive compound.
I Ru
S H 3 t -qlr...
wherein R R R R R and R are hydrogen or nitro groups.
7 These compounds are respectively designated as follows:
A. 8-dicyanomethylene-8H-indeno[2,l-b]thiophene. B. 4-dicyanomethylene-4H-indeno[ l ,2-b]thiophene. The electrophotographic light-sensitive materials of the present invention may be prepared by forming a photoconductive layer on an electroconductive support, the photoconductive layer comprising any of a variety or organic photoconductive monomers such as N- vinylcarbazole or organic photoconductive polymers as poly-N-vinylcarbazole and 4- dicyanomethylene-4H-indeno[1,2-b]thiophene or 8- dicyanomethylene-8H-indeno[2, l -b]thiophene or their derivatives as indicated above. 4-decyanomethylene- 4H-indeno[l,2-b]thiophene or 8-dicyanomethylene 8H-indeno[2,l-b]thiophene or their derivatives are utilized in an amount of from 0.01 to 1.2 mole per mole of organic photoconductive monomer or per monomeric unit of the organic photoconductive polymer (1 mole of the organic photoconductive polymer is represented by monomeric unit of the polymer).
4-dicyanomethylene-4H-indeno[1,2-b1thiophene or 8-dicyanomethylene-8I-I-indeno[2,1-b]thiophene and its derivatives for use in accordance with the present invention are shown by structural formulas below:
3 2-nitro-4-dicyanomethylene-4H-indeno[ 1,2-
blthiophene 6-nitro-4-dicyanomethylene-4H-indeno[1,2-
b]thiophene 2,6-dinitro-4-dicyanomethylene-4H-indeno[1,2-
b]thiophene v O N NC'CCN 6,8-dinitro-4-dicyanomethylene-4H-indeno[1,2-
b]thiophene NC'CCN 2,6,8-trinitro-4-dicyanomethylene-4H-indeno[1,2-
b]th|ophene 5O NC'C'CN (VII) 8-dicyanomethylene-8H-indeno-[2,l-b]thiophene 4C C CN 2-nitro-8-dicyanomethylene-8H-indeno-[2, l-
b]thi'ophene 6 -nitro-8-dicyanomethylene-8H-indeno-[2, l
blthiophene NC-C'CN OgN 2,6-dinitro-8-dicyanomethylene-8H-indeno-[ 2, l
b]thiophene 4,6-dinitro-8-dicyanomethylene-8 H-indeno-[2, l
b ]thiophene NC "C "CH 2,4,6-trinitro-8-dicyanomethylene-8H-indeno-[ 2, l
b]thiophene Organic photoconductive compounds for use in accordance with the present invention include the followmg:
Preferred organic photoconductive polymers include poly-N-vinylcarbazole, chlorinated or brominated poly-N-vinylcarbazole, polyvinylpyrene, polyvinylnaphthalene, polyvinylanthracene, poly-9- vinylfluorene, poly-l-arylimidazole, bromopyreneformaldehyde resin and poly-p-phenylene-l ,3 ,4- oxadiazole.
Electrophotographic light-sensitive materials in accordance with the present invention can be produced, for example, as follows:
From about 0.01 to about 1 mole .of 4- dicyanomethylene-4H-indeno[l,2b]thiophene or 8- dicyanomethylene-8H-indeno[2,l-b]thiophene or their derivatives as shown above is mixed with 1 mole of the organic monomer or monomeric unit of the organic photoconductive polymer and the'mixture is dissolved obtained was evaluated using Electrostatic paper analyser Type SP-428 sold by kawaguchi Denki Seisakusho as follows:
The material obtained above was divided into two 5 parts. The photoconductive layer was negatively or positively charged by a corona discharge of about 6kV or +6kV for 20 seconds to obtain a surface electric potential Vdo and then subjected to dark decay for 20 seconds to obtain a surface residual potential Vpo.
in an organic solvent such as tetrahydrofuran or dioxl0 T g light-Sensitive i l exposed to a ane to prepare a light-sensitive solution. Polyester tungsten fllafnent Whose 1lll1mma ne at the resin, novolac resin or acrylic resin may, if desired, be faee of e hght'sensltlve layer was adlusted to be 20 added to this solution. Furthermore, polychlorobiphe; T (Seconds) required t0 reduce the f fi nyl may be added to this Solution The resulting gh electric potential to one half or one fifth of the residual sensitive solution is then applied to a surface of an'elec- 15 Surface Potentlal P were measured- The ameems of troconductive support. for example, using a doctor exposure, 1 2 (lux'sec) and E (lux-sec),requ1red to blade, left to Set and flwndriedv reduce the surface electric potential to one half and The following Examples are given by way of illustraone fifth of P are calculated by lux Xfl ction only. onds). The E and E represent the sensitivity of the 2O electrophotographic light-sensitive material. The lower h EXAMPLE 1 the value of E 'or E the higher the sensitivity of the A light-sensitive solution containing a photoconducllght'sensm've matenal- The Value of E112 and E115 tive composition for use in the production of a photoare Shown the Table 1 below conductive layer was prepared from the following ingredients: T bl 1 Charge Vpo 1 E E gu'c-ilm-iltll-gyllfflfbflZole 387 mg (2m moles) v g l 'z dicyanomethylene-4H- indenol l.2-b]thiophene 65mg (0.2m mole) :22 H Polyester Adhesive 49000 38 mg (Trade mark of polyester resin sold by El. Du Pont de Nemours & Co. Inc.)
Similar results are obtained with the corresponding This light-sensitive solution was applied as a coat on 8-dicyanomethylene-8H compound. an aluminium layer on a polyester resin film (thickness: 75 t), using a doctor blade set at a 200 u gap, and then EXAMPLES 2 8 dried in a desicator having silica gel to evaporate a sol- Electrophotographic light-sensitive materials (No. 2 vent, and further dried at a temperature of 60C for No. 8) of the present invention were obtained by reabout 10 minutes and at a temperature of 120C for 40 peating the same procedure as that of Example 1 exabout 2 minutes. A photoconductive layer having a cept that organic photoconductive compound, sensithickness of about 7 p. was formed on the aluminium tizer, Polyester Adhesive 49000 and tetrahydrofuran layer. were used as shown in the following Table 2 and thick- The sensitivity of the electrophotographic lightness of photoconductive layer was that as shown in sensitive material (No. l) of the present invention thus Table 2.
Table '2 poly-N-vinyl- 6,8-dinitro- Polyester Tetrathickcarbazole 4-dicyanomethyl-' Adhesive h droness ene-4H-indeno 49000 uran of l 1 lphoto- No. 2 thiophene conduc- We layer 290 mg 243 mg 46 mg 5.2 g about (l.5 m moles) (0.75 m mole) 12 p. l-bromopyrene formaldehyde do. do. do. do. No. 3 resin 586 mg mg 290 mg 5.3 g about (2 m moles) (0.2 m mole) llu 'do. do. do. do. do. No.4 586mg mg i 324 mg 3.9 g about (2 m moles) (0.4 in mole) llu poly-N-vinyl- 2,6,8-trinitrodo. do. do. carbazole 4-dicyanomethyldo. do. do.
ene-4H-indeno No. 5 lthiophene 387 mg 37 mg 37 mg 6.1 g about (2 m moles) (0.] m mole) 4 u l-bromopyrene do. do. do. do.
formaldehyde about ,u
about 10 y.
about 10 p.
1) Chlorine is contained in a proportion of one chlorine atom per monomeric unit of poly-N-vinyl carbazole.
' 2) Bromine is contained in a proportion of one bromine atom per two monomeric units of poly-N-vinyl-carbazole.
Vpo, E and E of the light-sensitive materials No. 2 No. 8 were measured by repeating the same procedure as that of Example 1. The values obtained are shown in the Table 3 below.
" Table 3hz,l/32
No. C harge Vpo 112 175 (V) (lux'sec) (lux-sec) in the Examples supra, only 6.8-dinitro-4- dicyanomethy1ene-4H-indeno[ l ,2-b]thiophene (Formula V) and 2,6,8-trinitro-4-dicyanomethy1ene-4H- indeno[1,2-b]thiophene (Formula V1) were used as a sensitizer. However, the values of Vpo, E and E similar to those as shown in the Tables 1 and 3 can be obtained by using 4-dicyanomethylene-4H-indeno [1,2-b1thiophene or its derivatives as shown in Formulas 1 1V in place of the above-mentioned two 4- dicyanomethy1ene-4H-indeno-[ l ,2-b]thiophene derivatives in amount of from 0.01 to 1 mole per monomeric unit of poly-N-vinylcarbazole, chlorinated or brominated poly-N-vinylcarbazole, or l-bromopyrene formaldehyde resin.
Similar results are obtained with the corresponding 8-dicyanomethylene-8H compounds with the same compositions.
Electrophotographic light-sensitive materials having sensitivity to visible light can be produced with an organic photoconductive compound having no sensitivity to visible light by adding 4-dicyanomethy1ene-4H- indeno[l,2-b]thiophene or 8-dicyanomethylene-8H- indeno[2,l-b] thiophene or their derivatives to said organic photoconductive compounds.
The 4-dicyanomethylene-4H-indeno[ 1,2- b]thiophene compounds of this invention are novel.
Such 4-dicyanomethylene-4H-indeno[ l ,2- b]thiophene and its derivatives can be prepared by the process as described below.
R COOR s x (1) Benzoic acid Thiophene ester derivative derivative 1 i X2 2 00R 2 0t thienylbenzoic ac id ester derivat ive formamide at a temperature of from 50C to C. 7
2 tK-th1enylbenzoic acid derivative the reaction of ring closure as shown above is carried out in the presence of polyphosphoric acid at a temperature of from 70C to 150C. 9
I +HNO3) 2 WM R2 Q Indenothiophenone derivative The nitration as shown above if it is carried out is effected in the presence of cone. H 80 at a temperature of from 0C to C.
The reaction as shown above is carried out in the presence of piperidine in a solution of tetrahydrofuran.
The novel compounds of formula 6 of the present invention as shown above is most useful as a sensitizer for organic photoconductive compounds such as poly-N- vinylcarbazole.
The processes of preparing 6,8-dinitro-4- dicyanomethylene-4H-indeno[ 1 ,2-b]thiophene and 2,- 6,8-trinitro-4-dicyanomethylene-4H-indeno[ 1,2- blthiophene are shown in detail below:
13 g (0.05 mole) of methyl 2-chloro-3,5- dinitrobenzoate (mp 193 196C, Formula 1 as shown above) and 21 g (0.1 mole) of 2-iodothiophene (b.p. 71 73C at 16 mm Hg, Formula 2) were dissolved in 100 ml of dimethylformamide and the solu tion was heated at a temperature of 70C. To this solution was added 20 g of active cupper powder (as prepared by the method disclosed in Journal of American Chemical Society Vol. Page 4219 (1933) by E. C. Kleiderer and R. Adams) over 10 minutes and the solution was stirred at a temperature of about C for 50 minutes. After the solution has been cooled, the reaction product was poured into 500 ml of cold water. The precipitate thus produced was filtered off and washed with water. After water was removed from the precipitate, the precipitate was added to 500 ml of acetone. After the stirring has been continued, the solution was filtered. The filtrate was treated with active carbon, and then filtered. The filtrate was condensed to obtain a crude product. 13.1 g of a yellowish crystalline product (m.p. 134 135C) was obtained in an yield by recrystallization of the crude product from ethyl alcohol. This product was identified to be methyl 2-athienyl-3,S-dinitrobenzoate (Formula 3) by ultimate red absorption spectrum at 1730 cm.
23.6 g of methyl 2-a-thienyl-3,S-dinitrobenzoate (Formula 3) thus obtained was dissolved in ml of dioxane and to this solution was added an aqueous so- 0 lution of NaOH (6 g of NaOH in 200 ml of water) and the stirring was continued for 3 hours. To this solution was added a small amount of active carbon and the sol-fiicyanomethybnetH-indeno[l,2-b]
thiophene or its derivatives v Found lution was filtered. To the filtrate was added a cold water and the filtrate was neutralized with 6H-HC1 with cooling to obtain a yellowishgcrystalline product. The crystalline product was filtered off and washed with water, and then dried. Ayc'rude product (m.p. 171
172C) was obtained in a yield of 21.5 g. A yellowish crystalline product (m.p. 172.5- 173.5C) was obtained by the recrystallization of the crude product from benzene. This product was identified to be 2-athie nyl-3,S-dinitrobenzoic acid (Formula 4) by ulti-- mate analysis? Analysis:
C(7r) H(%) N(%) S(%) Calc'ulated for 44.90 2.06 9.52 10.90
' C H N O S The presences of carbonyl group and hydroxyl group were respectively proved by infrared absorption spectrum at 1,730 cm and 3,000 cm".
To 2g of 2-a-thienyl-3,S-dinitrobenzoic acid (Formula 4) was added 60 g of polyphosphoric acid and the mixture was heated at a temperature of from 130C to 140C. After cooling, the reaction mixture was poured into 200 ml of cold water. The precipitate thus produced was filtered off and washed with an aqueous so- Analysis:
C(7r) H(7() NW1) S(%) Calculated for 47.83 1.46 10.11 11.61
iiH4 2 s Found: 47.65 1.57 10.01 11.62
The presence of carbonyl group was proved by infrared absorption spectrum at 1730 cm.
1.5 g 6,8-dinitro-4H-indeno[l,2-b]thiophen-4'one (Formula 5) was dissolved in 30 ml of cone. H SO, and to this solution was added drop-wise with stirring, 5 ml of HNO (S.G. 1.38), at atemperature of from 5C to 10C, over 30 minutes. Stirring was continued at this temperature for 1.5 hours. This solution was poured into 200 m1 of cold water. A yellowish crystalline product separated from the solution. The crude product was filtered and washed with water and then dried. 1.4 g of a yellowish needle-like crystalline product (m.p. 223 223.5C) was obtained in an 80.5% yield by the recrystallization of the crude product from dioxane-ethyl alcohol. This product was identified to be a novel compound of 2,6,8-trinitro-4H-indeno[ 1,2-b]thiophen- 4-one (Formula 6) by ultimate analysis.
Analysis:
C( 7z) H('/r) N(%) S(7z) Calculated for 41.16 0.93 13.08 9.98
C 11M 1 Found 40.90 1.32 12.90 10.23
The presence of carbonyl group was proved by infrared absorption spectrum at 1,730 cm.
8g of 6,8-dinitro-4l-l-indeno[1,2-blthiophen-4-one (Formula 5) and 3.8g of malonitrile were dissolved in ml of tetrahydrofuran and to this solution was added a few drops of piperidine under reflux. After the reflux was continued to 20 minutes, tetrahydrofuran was distilled off at reduced pressure. The residue was washed with methyl alcohol. 4.4g of 6,8-dinitro-4- dicyanornethylene-4H-indeno[1,2-b]thiophene (Formula V; m.p. 244C 245.5C) was obtained by recrystallization of the residue from dioxane.
Analysis:
C(%) H(%) N(%) S(%) Calculated for 51.85 1.24 17.28 9.89
C H N P,S Found 51.82 1.01 17.62 9.80
The presence of cyano group was proved by infrared absorption spectrum at 2,230".
10g of 2,6,8-trinitro-4H-indeno['1,2-b]thiophen-- 4-one (Formula 6) and 4g of malonitrile were dissolved in a mixture of 200 ml of tetrahydrofuran and 200 ml of methyl alcohol and to this solution was added a few drops of piperidine under reflux. After the reflux was continued for 20 minutes, the crystals separated from the solution were filtered. After the crystals have been recrystallized from a mixture of dioxane and acetonitrile, 8g of 2,6,8-trinitro-4-dicyanomethylene-4H- indeno[l,2-b]thiophene (Formula V1; m.p. over 300C) was obtained in the form of red plate crystal.
The presence of cyano group was proved by infrared absorption spectrum at 2,220 cm".
The corresponding S-diCyanomethylene-SH compounds are also novel. They are prepared by the reaction of malononitrile on the corresponding 81-1,- indeno[2,1-b]thiophene-8-ones as illustrated above. The starting materials are prepared by the procedures described in:
MacDowell, et al; J. Org. Chem. 32, 2441 (1967) Dubard, et a1; Academy Science Ser. C. 271 (4) 311 (1970).
What is claimed is:
1. An electrophotographic light-sensitive material having a photoconductive layer formed on an electroconductive support, the photoconductive layer comprising an organic photoconductive monomer or an organic photoconductive polymer, and a sensitizing compound of the formula;
NC -c CN wherein R R R R R and R are hydrogen or nitro groups wherein the sensitizing compound is present in an amount of from about 0.01 to about 1.2 mole per mole of the organic photoconductive monomer or per monomeric unit of the organic photoconductive polymer.
2. An electrophotographic light-sensitive material according to claim 1 wherein the sensitizing compound is

Claims (5)

1. AN ELECTROPHOTOGRAPHIC LIGHT-SENSITIVE MATERIAL HAVING A PHOTOCONDUCTIVE LAYER FORMED ON AN ELECTROCONDUCTIVE SUPPORT, THE PHOTOCONDUCTIVE LAYER COMPRISING AN ORGANIC PHOTOCONDUCTIVE MONOMER OR AN ORGANIC PHOTOCONDUCTIVE POLYMER, AND A SENSITIZING COMPOUND OF THE FORMULA:
2. An electrophotographic light-sensitive material according to claim 1 wherein the sensitizing compound is 6,8-dinitro-4-dicyanomethylene-4H-indeno(1,2-b)thiophene.
3. An electrophotographic light-sensitive material according to claim 1 wherein the sensitizing compoUnd is 2,6,8-trinitro-4-dicyanomethylene-4H-indeno(1,2-b)-thiophene.
4. An electrophotographic light-sensitive material according to claim 1 wherein the sensitizing compound is 2,6-dinitro-8-dicyanomethylene-8H-indeno(2,1-b)thiophene.
5. An electrophotographic light-sensitive material according to claim 1 wherein the sensitizing compound is 2,4,6-trinitro-8-dicyanomethylene-8H-indeno(2,1-b)thiophene.
US425967A 1972-12-28 1973-12-19 Electrophotographic photoconductive layer comprising an organic photoconductor and a dicyanomethylene-indenothiophene sensitizer Expired - Lifetime US3871883A (en)

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US4046563A (en) * 1974-03-25 1977-09-06 Xerox Corporation Photoconductive composition containing a tricyanopyrene, article and process of use
US4063947A (en) * 1975-10-29 1977-12-20 Xerox Corporation Photoconductive insulating films comprising fluorenone-substituted oligomers
US4066454A (en) * 1973-11-19 1978-01-03 Kabushiki Kaisha Ricoh Electrophotographic light-sensitive material containing indenothiophenone or its derivative and process of preparing indenothiophenone and its derivative
US4184871A (en) * 1974-04-18 1980-01-22 Mitsubishi Chemical Industries Ltd. Photosensitive composition for electrophotography
EP0069397A1 (en) * 1981-07-07 1983-01-12 Mitsubishi Kasei Corporation Electrophotographic plate
DE3730258A1 (en) * 1986-09-10 1988-04-07 Canon Kk ELECTROPHOTOGRAPHIC LIGHT SENSITIVE RECORDING MATERIAL, 5H-DIBENZO (A, D) CYCLOHEPTANYLIDEN DERIVATIVE, 5H-DIBENZO (A, D) CYCLOHEPTENYLIDEN DERIVATIVE AND METHOD FOR THE PRODUCTION THEREOF
US5306587A (en) * 1991-09-24 1994-04-26 Agfa-Gevaert, N.V. Photosensitive recording material
US20150214701A1 (en) * 2012-10-05 2015-07-30 Thomas Alfred Paul Apparatus Containing A Dielectric Insulation Gas Comprising An Organofluorine Compound

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US4066454A (en) * 1973-11-19 1978-01-03 Kabushiki Kaisha Ricoh Electrophotographic light-sensitive material containing indenothiophenone or its derivative and process of preparing indenothiophenone and its derivative
US4046563A (en) * 1974-03-25 1977-09-06 Xerox Corporation Photoconductive composition containing a tricyanopyrene, article and process of use
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EP0069397A1 (en) * 1981-07-07 1983-01-12 Mitsubishi Kasei Corporation Electrophotographic plate
DE3730258A1 (en) * 1986-09-10 1988-04-07 Canon Kk ELECTROPHOTOGRAPHIC LIGHT SENSITIVE RECORDING MATERIAL, 5H-DIBENZO (A, D) CYCLOHEPTANYLIDEN DERIVATIVE, 5H-DIBENZO (A, D) CYCLOHEPTENYLIDEN DERIVATIVE AND METHOD FOR THE PRODUCTION THEREOF
US5306587A (en) * 1991-09-24 1994-04-26 Agfa-Gevaert, N.V. Photosensitive recording material
US20150214701A1 (en) * 2012-10-05 2015-07-30 Thomas Alfred Paul Apparatus Containing A Dielectric Insulation Gas Comprising An Organofluorine Compound
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