US3586500A - Electrophotographic composition and element - Google Patents

Electrophotographic composition and element Download PDF

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US3586500A
US3586500A US772863A US3586500DA US3586500A US 3586500 A US3586500 A US 3586500A US 772863 A US772863 A US 772863A US 3586500D A US3586500D A US 3586500DA US 3586500 A US3586500 A US 3586500A
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perchlorate
photoconductive
pyrylium
radical
photoconductor
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Lawrence E Contois
Donald P Specht
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Eastman Kodak Co
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Eastman Kodak Co
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    • 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
    • G03G5/0635—Heterocyclic compounds containing one hetero ring being six-membered
    • G03G5/0637—Heterocyclic compounds containing one hetero ring being six-membered containing one hetero atom

Definitions

  • the processof xerography employs an electrophotographic element comprising a support material bearing a coating of a normally insulating material whose electrical resistance varies with the amount of incident actinic radiation it receives during an imagewise exposure.
  • the element commonly termed a photoconductive element, is first given a uniform surface charge after a suitable period of dark adaptation.
  • the element is then exposed to a pattern of actinic radiation which has the effect of differentially reducing the potential of the surface charge in accordance with the relative energy contained in various parts of the radiation pattern.
  • the differential surface charge or electrostatic latent image remaining on the electrophotographic, element is then made visible by contacting the surface with a suitable electroscopic marking material.
  • marking material or toner Whether contained in an insulating liquid or on a dry carrier, can be deposited on the exposed surface in accordance with either the charge pattern or in the absence of charge pattern as desired.
  • the deposited marking material may then be either permanently fixed to the surface of the sensitive element by known means such as heat, pressure, solvent vapor and the like or transferred to a second element to which it may similarly be fixed.
  • the electrostatic latent image can be transferred to a second element and developed there.
  • Various photoconductive insulating materials have been employed in the manufacture of electrophotographic elements. For example, vapors of selenium and vapors of selenium alloys deposited on a suitable support and particles of photoconductive zinc oxide held in a resinous, film-forming binder have found wide application in present-day document copying applications.
  • organic photoconductor materials referred to above are inherently light sensitive, their degree of sensitivity is usually low.
  • the spectral response of organic photoconductor materials is generally limited to the ultraviolet or blue region of the spectrum. Often the spectral response of such materials can be extended into the visible region of the spectrum by the use of sensitizers. Such sensitization can be advantageous in that common tungsten light sources can then be used for exposure.
  • the spectral response for such a sensitized system is usually directly related to the absorbance spectra of the individual components of the system.
  • sensitization of a photoconductive composition to the infrared region requires the use of sensitizers having an absorbance maximum in this region. It has generally been found that such a means for sensitization is an inefficient one. Additionally, the sensitizers which have an infrared absorbance maximum are often compounds having very complex structures which render them either unstable or extremely difficult to synthesize economically.
  • Another object of this invention is to provide novel sensitized photoconductive elements having a spectral response in the far red and near infrared region.
  • sensitizers of the present invention include those having the following structural formulas:
  • X is a sulfur atom or an oxygen atom
  • Z is an anionic function including such anions as perchlorate, fluoroborate, sulfonate, periodate, p-toluenesulfonate, etc.;
  • R is a hydrogen atom, a halogen atom such as chlorine, bromine, etc.; an alkyl radical having from 1 to 12 carbon atoms such as methyl, ethyl, isopropyl, n-butyl, pentyl, octyl, decyl, dodecyl, etc., including cycloalkyl such as cyclopentyl, cyclohexyl, etc.; an alkoxy radical having from 1 to 4 carbon atoms in the alkyl moiety such as methoxy, ethoxy, propoxy, butoxy, etc.; an aryl radical such as phenyl, naphthyl, etc., including substituted aryl radicals; an aralkenyl radical having from 2 to 6 carbon atoms in the alkenyl moiety such as ethenyl, propenyl, hexenyl, etc.; and a monoor polycyclic, heterocyclic radical typically having 5 or 6
  • R is a hydrogen atom; a halogen atom as above; an alkyl radical as above including halogen substituted alkyl radical such as chloromethyl, dichloropropyl, bromopentyl, etc.; an alkoxy radicalas above; an aryl radical as above; an aroyl radical such as benzoyl, naphthoyl, etc.; and an alkoxycarbonyl radical having from 1 to 4 carbon atoms in the alkoxy moiety such as methoxy, ethoxy,
  • any two of R R R R and R attached to adjacent carbon atoms represent the atoms necessary to form a fused ring having from 5 to 8 carbon atoms and can be aromatic, alicyclic, unsaturated alicyclic radicals including the corresponding substituted radicals having such substituents as a halogen atom as above, an alkyl radical as above, an aryl radical as above and an aralkenyl as above;
  • R and R can be a hydrogen atom, an alkyl radical as above and an aryl radical as above;
  • R is a hydrogen atom, an alkoxycarbonyl radical as in R above and an aryl radical;
  • R is a hydrogen atom, a hydroxy radical, an alkoxy radical as above or an aryl radical.
  • Typical useful sensitizers that can be used in the invention include the following representative compounds:
  • Typical useful sensitizers that can be used in the invenductors used to form an interaction product which gives rise to a considerable extension of the absorption range of the photoconductors.
  • the useful photoconductors alone do not exhibit any appreciable absorption in the red region of the spectrum.
  • an interaction product results which in general has a long Wavelength radiation absorption maximum at wavelengths of greater than about 665 me. Not only is the absorption range of the photoconductor greatly extended, but more important is the fact that this increased absorption is electrophotographically useful.
  • a sensitized photoconductive composition of this invention has a spectral distribution of sensitization that is substantially changed from that of the individual components such that the interaction product exhibits significant long wavelength spectral sensitvity to far red and infrared radiation.
  • far red refers to the portion of the spectrum including light having a Wavelength in the range of from about 650 to about 700 my
  • near infrared refers to light having a wavelength of from about 700 to about 900 me.
  • the sensitizers by themselves do not have any appreciable sensitivity in the red region of the spectrum.
  • the sensitizers used in the invention are effective for enhancing the sensitivity of a variety of photoconductors.
  • the preferred photoconductors are those organic arylamine-containing compounds which exhibit an electrophotosensitivity to light and which are capable of interacting with the sensitizer so as to produce a substantial extension of the spectral distribution of sensitization to include the far red and infrared portion ofthe spectrum.
  • the useful photoconductors by themselves have very little absorption in the red region, for example, one useful photoconductor has a long wavelength absorption maximum at about 420 mp. Furthermore, any slight long wavelength absorption which the photoconductor alone may exhibit is not useful absorption in that it does not result in any long wavelength spectral sensitivity.
  • Useful photoconductive compounds which exhibit such interaction with the sensitizers would include the following:
  • Electrophotographc elements of the invention can be prepared with organic photoconductive compounds and the sensitizing compounds of this invention in the usual manner, i.e., by blending a dispersion or solution of the photoconductive compound together with an electrically insulating, film-forming resin binder when necessary or desirable and coating or forming a self-supporting layer with the photoconductive composition.
  • a suitable amount of the sensitizing compound is mixed with the photoconductive coating composition so that after thorough mixing the sensitizing compound is uniformly distributed throughout the desired layer of the coated element.
  • the amount of sensitizer that can be added to a photoconductor-containing layer to give effective increases in speed can vary widely. The optimum concentration in any given case will vary with the specific photoconductor and sensitizing compound used.
  • an appropriate sensitizer is added in a concentration range from about 0.0001 to about 30 percent by weight based on the Weight of the film-forming coating composition.
  • a sensitizer is added to the coating composition in an amount from about 0.005 to about 5.0 percent by weight of the total coating composition.
  • Preferred binders for use in preparing the present photoconductive layers comprise polymers having fairly high dielectric strength which are good electrically insulating film-forming vehicles.
  • Materials of this type comprise styrene-butadiene copolymers; silicone resins; styrenealkyd resins; silicone-alkyd resins; soya-alkyd resins; poly (vinyl chloride); poly(vinylidene chloride); vinylidene chloride-acrylonitrile copolymers; poly(vinyl acetate); vinyl acetate-vinyl chloride copolymers; poly(vinyl acetals), such as poly(vinyl butyral); polyacrylic and methacrylic esters, such as poly(methylmethacrylate), poly(n-butylmethacrylate), poly(isobutyl methacrylate), etc.; polystyrene; nitrated polystyrene; polymethylstyrene; isobutylene polymers
  • Suitable resins of the type contemplated for use. in the photoconductive layers of the invention are sold under such tradenames as Vitel PE-101, Cymac, Piccopale 100, Saran F-220 and Lexan 145.
  • Other types of binders which can be used in the photoconductive layers of the invention include such materials as paraffin, mineral waxes, etc.
  • Solvents of choice for preparing coating compositions of the present invention can include a number of solvents such as benzene, toluene, acetone, Z-butanone, chlorinated hydrocarbons, e.g., methylene chloride, ethylene chloride, etc., ethers, e.-g., tetrahydrofuran, or mixtures of these solvents, etc.
  • solvents such as benzene, toluene, acetone, Z-butanone, chlorinated hydrocarbons, e.g., methylene chloride, ethylene chloride, etc., ethers, e.-g., tetrahydrofuran, or mixtures of these solvents, etc.
  • the photoconductor substance is present in an amount equal to at least about 1 weight percent of the coating composition.
  • the upper limit in theamount of photoconductor substance present can be widely varied in accordance with usual practice. In those cases where a binder is employed, it is normally required that the photoconductor substance be present in an amount fromabout 1 weight percent of the coating composition to about 99 weight percent of the coating composition.
  • a preferred weight range for the photoconductor substance in the coating composition is from about weight percent to about 60weight percent.
  • coating thicknesses of the photoconductive composition on a support can vary widely. Normally, a coating in the range of about 0.001 inch to about 0.01 inch before drying is useful for the practice of this invention. The preferred range of coating thickness is found to' be in the range from about 0.002 inch to about 0.006 inch before drying although useful results can be obtained outside of this range.
  • Suitable supporting materials for coating the photoconductive layers of the present invention can include any of a wide variety of electrically conducting supports, for example, paper (at a relative humidity above percent); aluminum-paper laminates; metal foils such as aluminum foil, zinc foil, etc.; metal plates, such as aluminum, copper, zinc, brass and galvanized plates; vapor deposited metal layers such as silver, nickel, aluminum and the like coated on paper or conventional photographic film bases such as cellulose acetate,'polystyrene, 'etc.'Such conducting materials as nickel can be coated by vacuum deposition on transparent film supports in sufficiently thin layers to allow electrophotographic elements prepared therewith to be exposed from either side of such elements.
  • electrically conducting supports for example, paper (at a relative humidity above percent); aluminum-paper laminates; metal foils such as aluminum foil, zinc foil, etc.; metal plates, such as aluminum, copper, zinc, brass and galvanized plates; vapor deposited metal layers such as silver, nickel, aluminum and the like coated on paper or conventional photographic film bases such as cellulose acetate,
  • An especially useful conducting support can be prepared by coating a support material such as poly(ethylene terephthalat'e) with a conducting layer containing a semiconductor dispersed in a resin.
  • a support material such as poly(ethylene terephthalat'e)
  • a conducting layer containing a semiconductor dispersed in a resin Such conducting layers both with and without insulating barrier layers are described in US. Pat. 3,245,833.
  • a suitable conducting coating can beprepared from the sodium salt of a carboxyester lactone of maleic anhydride and a vinyl acetate polymer.
  • Such kinds of conducting layers and methods for their optimum preparation and use are disclosed in U.S. 3,007,901 and 3,267,807.
  • the elements of the present invention can be employed in any of the well-known electrophotographic processes which require. photoconductive layers.
  • One such process is the aforementioned xerographic process.
  • theelectrophotographic element is given a blanket electrostatic charge by placing the same under a corona discharge which serves to give a uniform charge to the surface of the photoconductive layer. This charge is retained on the layer by virtue of the substantial insulating property of the layer, i.e., the low conductivity of the layer in the dark.
  • the electrostatic charge formed on the surface of the photoconducting layer is then selectiively dissipated from the surface of the layer byexposure to light through an imagebearing transparency by a conventional exposure operation such as, for example, by contact-printing technique,
  • the developing electrostatically attractable particles can be in the form of a dust or a pigment in a resinous carrier or a liquid developer can be used in which the developing particles are carried in an electrically insulating liquid carrier.
  • a control coating is prepared from the following ingredients:
  • the above homogeneous photoconductive composition is coated at a wet thickness of 0.004 inch onto a poly- (ethylene terephthalate) film support carrying a conductive layer of the sodium salt of a polymeric lactone as described in US. Pat. No. 3,260,706.
  • the coating block temperature is maintained at F.
  • the resultant element is called Element 1 (control).
  • the above procedure is repeated with the addition of 0.01 g. of 2-chloro-3- phenylnapl1tho[2,1 b]pyryliurn perchlorate as the sensitizer prior to coating.
  • the resultant element is called Element 2.
  • the resultant electrophotographic elements are then electrostatically charged under a corona source until the surface potential, as measured by an electrometer probe, reaches about 600 volts.
  • the charged elements are then exposed to a 3000 K. tungsten light source through a stepped density gray scale.
  • the exposure causes reduction of the surface potential of the elements under each step of the gray scale from its initial potential, V to some lower potential, V, whose exact value depends on the actual amount of exposure in meter-candle-seconds received by the area.
  • the results of the measurements are then plotted on a graph of surface potential V vs. log exposure for each step.
  • the actual positive or negative speed of the photoconductive composition used can then be expressed in terms of the reciprocal of the exposure required to reduce the surface potential to any fixed arbitrarily selected value.
  • the actual positive or negative speed is the numerical expressionof 10 divided by the exposure in meter-candleseconds required to reduce the 600 volt charged surface potential to a value of 500 volts volt shoulder speed) or to a value of 100 volts (100 volt toe speed).
  • the speeds of the elements are recorded in Table I below.
  • Element 5 exhibits an absorption maximum only in the These elements can then be charged, eXpOSed and devel' ultraviolet region of the spectrum; whereas, Element 6 p with liquid developers Of the yp described in U- 10 has a long Wavelength absorption peak at about 700 my Pat. NO- 2,907,674 to form visible images.
  • the optical toned wedge pectrograms howing ensitivity e absorption of the above two transparent coatings is then tending i h i f d i measured by a commercially available spectrophotom- EXAMPLE 4 eter such as a Beckman Model B spectrophotometer.
  • the coating of Element 1 (control) has an absorption
  • Two series of electrophotographic elements are prerange extending through the visible light region to 570 m with no absorption being observed at 700 m
  • Element 2 shows an additional unexpected long wavelength absorption peak at 700 m with absorption extending well into the infrared region of the spectrum.
  • the spectral sensitivity of the elements is measured by electrostatically charging the elements under a corona source and exposing in a standard spectrograph. After exposure the elements are toned with a developer of the type described in US. Pat. 2,907,674 to form wedge spectro grams. The spectrograms show Element No. 2 to have significant sensitivity in the far red and infrared portion of the spectrum.
  • EXAMPLE 2 Two electrophotographic elements are prepared as in Example 1.
  • the first element (No. 3) carries a photoconductive layer prepared from the following ingredients:
  • Triphenylamine photoconductor 0.25 10H indeno[l,2 b]benzo[e]pyrylium perchlorate (sensitizer) 0.01
  • Element No. 3 is a control which contains a non-interacting photoconductor.
  • Element 4 is similar to No. 3 with the exception that 4,4'-bis(diphenylaminochalcone) is used as the photoconductor. These elements are then measured for electrophotographic speed as in Example 1. The speeds are shown in Table II below.
  • Electrophotographic Elements 5 and 6 are prepared similar to Elements 3 and 4, respectively, only using 2- chloro 3 phenylnaphtho[2,l-b]pyrylium perchlorate as the sensitizer in order to compare the results of using this sensitizer with a non-interacting and an interacting photoconductor, respectively. These elements are tested for electrophotographic speed as previously and the results are shown in Table III below.
  • the first series contains 4,4-bis(diphenylaminochalcone) as the photoconductor and the control series contains triphenylamine as the photoconductor.
  • the various elements are then measured for absorption at different Wavelengths as in Example 1.
  • the region of maximum long wavelength interaction absorption for each element of the invention is shown in Table IV below.
  • the absorption maximum is also shown for each corresponding element containing the non-interacting triphenylamine photoconductor (control).
  • EXAMPLE 5 An electrophotographic element is prepared as described in the previous examples using the following coating composition:
  • Methyl alcohol 1.0 ml.
  • EXAMPLE 3 j An electrophotographic element prepared as infExjample using 4-acetyltriphenylamine as the photoconductor. The elementis then measured for absorption as in Example 1 and found to have a long wavelength absorption peak at 720 mp. Next, the element is charged, exposed and developed as in the preceding examples to produce a wedge spectrogram. The spectrogram shows that the long wavelength absorption of this element is useful in that the sensitivity extends well into the infrared region.
  • the present sensitized electrically insulating photoconductive compositions have a usefnl sensitivity to light in the far red and near infrared portion of the spectrum. Consequently, the instant 'compositions and elements are particularly suited for use in, for example, infrared recording applications; I
  • a far red and near infrared sensitive photoconductive composition comprising an electrically insulating filmforming resin binder, an organic arylamine-containing photoconductor and a sensitizer material selected from the group of compounds having the formula:
  • Z is an anion
  • X isselected from the group consisting of oxygen and sulfur
  • R is selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl radical of from 1 to 12 carbon atoms, an alkoxy radical having from 1 to 4 carbon atoms in the alkyl moiety, an aryl radical, an aralk enyl radical having from 2 to 6 carbon atoms in the alkenyl moiety and a heterocyclic radical having 5 to 6 atoms in the hetero ring including at least one hetero atom selected from the group consisting of oxygen and sulfur;
  • R is selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl radical of from 1 to 12 carbon atoms, an alkoxy radical as above, an aryl radical, an aroyl radical and an alkoxycarbonyl radical having from 1 to 4 carbon atoms in the alkoxy moiety;
  • R is selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxy radical, an alkyl radical having from 1 to 12 carbon atoms, an alkoxy radical as in R a vinyl radical and an aryl radical;
  • R and R are each selected from the group consisting of a hydrogen atom and an alkyl radical of from 1 to 12 carbon atoms; when taken together, any two of R R R R and R attached to adjacent carbon atoms represent the atoms necessary to form a fused ring structure selected from the group consisting of aromatic, alicyclic and unsaturated alicyclic radicals having from 5 to 8 carbon atoms;
  • said photoconductor being present in an amount of at least about 1% by weight of the composition and said sensitizer material being present in an amount of about 0.0001 to about 30% by weight of the composition,
  • each of said photoconductor and said sensitizer material having substantially no sensitivity to radiation of a wavelength greater than about 650 m and said composition being characterized in that said photoconductor and sensitizer interact to give a long wavelength radiation absorption maximum at wavelengths of greater than about 665 Ill/L- 2.
  • An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition of claim 2.
  • a photoconductive composition as in claim 1 wherein the photoconductor is selected from the group consisting of: 4,4-bis(diphenylaminochalcone),
  • An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition of claim 4.
  • An electrophotographic element comprising a support having coated thereon a layer of a photoconductive composition of claim 1.
  • organic photoconductor is selected from the group consisting of 4,4'-bis(diphenylaminochalcone), bis(4-diphenylaminobenzal)acetone and 4 acetyltriphenylamine and the sensitizer material is selected from the group consisting of:
  • a far red and near infraredsensitive photoconductive composition comprising an electrically" insulating filmforming resin binder and organic photoconductor selected from the group consisting of 4,4 bis(diphenpylaminochalcone), bis(4-diphenylaminobenzo)acetone and'4-acetyltriphenylamine and a sensitizer material selected from the group of compounds having the formula:
  • Z- is an anion
  • X is selected from the group consisting of oxygen and sulfur
  • R is selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl radical of from 1 to 12 carbon atoms, an alkoxy radical having from 1 to 4 carbon atomsin the alkyl moiety, an aryl radical, an aralkenyl radical having from 2 to 6 carbon atoms in the alkenyl moiety and a heterocyclic radical havingS to 6 atoms in the hetero ring including at least one hetero atom selected from the group consisting of oxygen and sulfur;
  • R is selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl radical of from 1 to 12 carbon atoms, an 'alkoxy radical as above, an aryl radical, an aroyl radical, and an alkoxycarbonyl radical having from'l to 4 carbon atoms in the alkoxy moiety;
  • R is selected from the groupconsisting of a hydrogen atom, a,ha1ogen. atom, a hydroxy. radical, analkyltradical having from 1 'to 112 carbon atoms, an alkoxyradicalas in R a vinyl radical and an arylradical; n n I R and R 'a're each selected from the groupcons'isting of a hydrogenatom andan alkyl radical of from 1 to 12 carbon atoms; i.
  • any two of R R R R and R5 attached to adjacent carbon atoms represent the atoms necessaryto forma fused ring structure selected from thegroup consisting of aromatic, alicyclic and unsaturated alicyclic radicals having from 5 to 8 carbon atoms; f t "I said photoconductor being present in an amount of at least about 1% by weight of the composition and said sensitizer beingpresent in an amount of about 0.0001 to about 30%. by weight of the composition, each of said photoconductor. and said sensitizer'material having'sub: stantially no sensitivity to radiation of a wavelength greater than. about 650 my, s'aidscomposition characterized in that said photoconductor and sensitizer interact to exhibit a combined long Wavelength spectral sensitivity in the range of radiation having a wavelength of about 650 to about 900 m.
  • An electrophotographic element comprising a conductive support having coated thereon a. layer of a photoconductive composition of claim 9.

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US772863A 1968-11-01 1968-11-01 Electrophotographic composition and element Expired - Lifetime US3586500A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3881924A (en) * 1971-08-25 1975-05-06 Matsushita Electric Ind Co Ltd Organic photoconductive layer sensitized with trimethine compound
US3896112A (en) * 1971-10-21 1975-07-22 Ricoh Kk Bisbenzopyran and bisbenzopyrylium adducts
USRE28698E (en) * 1970-03-13 1976-01-27 Matsushita Electric Industrial Co., Ltd. Electrophotographic material containing sensitizers
US4233443A (en) * 1977-07-06 1980-11-11 Eastman Kodak Company Novel radiation sensitive compounds and radiation sensitive compositions containing the same
US4424268A (en) 1982-11-22 1984-01-03 Eastman Kodak Company Pyrylium- and thiopyrylium-sensitized low-persistence photoconductive compositions and elements
US5024911A (en) * 1987-06-03 1991-06-18 Fuji Xerox Co., Ltd. Electrophotographic photoreceptor having an electric charge generating layer comprising a pyrylium compound
US5049464A (en) * 1988-12-29 1991-09-17 Canon Kabushiki Kaisha Photosensitive member for electrophotography
US5079118A (en) * 1989-01-20 1992-01-07 Canon Kabushiki Kaisha Photosensitive member for electrophotography with substituted pyrene
US5262261A (en) * 1988-12-29 1993-11-16 Canon Kabushiki Kaisha Photosensitive member for electrophotography
US5262549A (en) * 1991-05-30 1993-11-16 Polaroid Corporation Benzpyrylium dyes, and processes for their preparation and use

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE28698E (en) * 1970-03-13 1976-01-27 Matsushita Electric Industrial Co., Ltd. Electrophotographic material containing sensitizers
US3881924A (en) * 1971-08-25 1975-05-06 Matsushita Electric Ind Co Ltd Organic photoconductive layer sensitized with trimethine compound
US3896112A (en) * 1971-10-21 1975-07-22 Ricoh Kk Bisbenzopyran and bisbenzopyrylium adducts
US4233443A (en) * 1977-07-06 1980-11-11 Eastman Kodak Company Novel radiation sensitive compounds and radiation sensitive compositions containing the same
US4424268A (en) 1982-11-22 1984-01-03 Eastman Kodak Company Pyrylium- and thiopyrylium-sensitized low-persistence photoconductive compositions and elements
US5024911A (en) * 1987-06-03 1991-06-18 Fuji Xerox Co., Ltd. Electrophotographic photoreceptor having an electric charge generating layer comprising a pyrylium compound
US5049464A (en) * 1988-12-29 1991-09-17 Canon Kabushiki Kaisha Photosensitive member for electrophotography
US5262261A (en) * 1988-12-29 1993-11-16 Canon Kabushiki Kaisha Photosensitive member for electrophotography
US5079118A (en) * 1989-01-20 1992-01-07 Canon Kabushiki Kaisha Photosensitive member for electrophotography with substituted pyrene
US5262549A (en) * 1991-05-30 1993-11-16 Polaroid Corporation Benzpyrylium dyes, and processes for their preparation and use

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FR2022355A1 (enrdf_load_stackoverflow) 1970-07-31
DE1954538B2 (de) 1972-09-28
BE741045A (enrdf_load_stackoverflow) 1970-04-01
DE1954538A1 (de) 1970-05-27

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