US3526502A - Electrophotographic material - Google Patents

Electrophotographic material Download PDF

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US3526502A
US3526502A US636172A US3526502DA US3526502A US 3526502 A US3526502 A US 3526502A US 636172 A US636172 A US 636172A US 3526502D A US3526502D A US 3526502DA US 3526502 A US3526502 A US 3526502A
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perchlorate
vinylcarbazole
benzopyrylium
poly
electrophotographic
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Yoshinobu Murakami
Kazuhisa Morimoto
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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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
    • G03G5/07—Polymeric photoconductive materials
    • G03G5/071—Polymeric photoconductive materials obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • G03G5/072—Polymeric photoconductive materials obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising pending monoamine groups
    • G03G5/073—Polymeric photoconductive materials obtained by reactions only involving carbon-to-carbon unsaturated bonds comprising pending monoamine groups comprising pending carbazole groups
    • 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
    • G03G5/07—Polymeric photoconductive materials
    • G03G5/071—Polymeric photoconductive materials obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • 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

  • An improved electrophotographic material comprising a conductive support layer and a photoconductive insulating layer, the latter comprising a combination of a photoconductive polymeric compound and a benzopyrylium salt as a novel sensitizer, said photoconductive polymeric cornpound comprising at least one compound selected from the group consisting of poly-N-vinylcarbazole, poly-3,6- dibromo-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyacenaphthylene and polyvinylanthracene.
  • This invention relates to novel light-sensitive polymer layers and more particularly to electrophotographic lightsensitive polymer layers containing a benzopyrylium salt as a novel class of sensitizers of organic photoconductors.
  • the photoconductive material has a high photoconductivity in the long Wave length region of the visible spectrum.
  • Such a photoconductive material makes it possible for the electrophotographic 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 a short wave length region of the eX- posure light and do not satisfy entirely the above requirement.
  • sensitizer 1t is known that an addition of a so-called sensitizer can improve the above photoconductive materials in respect of photoconductivity and spectrum characteristics.
  • Conventional sensitizers are dyestuff compounds, such as triarylmethane dyes, Xanthene dyes, triazine dyes or acridine dyes, but the conventional sensitizers are not entirely satisfactory for improving the photoconductivity and the spectrum characteristics of the available photoconductive materials.
  • 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 Wave length region of the visible spectrum.
  • Another object of the invention is to provide electrophotographic materials having a high electric resistance in the dark.
  • FIG. 1 represents the wedge spectrogram for an electrophotographic material coated with unsensitized l0 weight percent brominated poly-N-vinylcarbazole in chlorobenzene.
  • IIG. 2 represents the wedge spectrogram for an electrophotographic material coated with 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.02 weight percent of 2-(rx-isopropyl-w-phenylbutadienyl) benzopyrylium perchlorate, said 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 10 Weight percent of brominated poly-N-vinylcarbazole sensitized with 0.02 weight percent of 2-(a-isopropyl-w-phenylbutadienyl)-6,7 dimethylbenzopyrylium perchlorate, said 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 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.02 weight percent of 2-(a-isopropyl-w-phenylbutadienyl)-6- phenyl-benzopyrylium perchlorate, said 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 10 weight percent of brominated poly-N-vinylcarbazole sensitized with 0.02 weight percent of 2-(4methoxystyryl)-S-phenylbenzopyrylium perchlorate, said 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 electrophotographic material coated with 10 weight percent poly- 3,6-dibromo-N-vinylcarbazole in chlorobenzene.
  • FIG. 7 represents the wedge spectrogram for an electrophotographic material coated with 10 weight percent of poly-3,6-dibromo-N-vinylcarbazole sensitized with 0.02 weight percent of 2-(4methoxystyryl)-3-phenyl-8-methoxybenzopyrylium perchlorate, said poly-3,6-dibromo- N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one Weight part of dichloroethane, and
  • FIG. 8 represents the wedge spectrogram for an electrophotographic material coated with 10 weight percent of poly-3,i6-dibromo-N-vinylcarbazole sensitized with 0.02 Weight percent of 2-(4-methoxystyryl)-3-(4methoXy phenyDbenzopyrylium perchlorate, said poly 3,6 dibromo-N-vinylcarbazole being dissolved in a solvent of four weight parts of chlorobenzene and one Weight part of dichloroethane.
  • the benzopyrylium salt compound (sensitizer) has the following formula:
  • R1 is H, phenyl, or aliphatic group such as methyl, ethyl,
  • propyl isopropyl, butyl or tertiary butyl
  • R2 is aryl such as phenyl or 4-biphenyl, hydroxyphenyl such as Z-hydroxyphenyl, 4-hydroxyphenyl or 3,4-dihydroxyphenyl, alkoxyphenyl such as 4-methoxyphenyl or 3,4-dimethoxyphenyl, aminophenyl such as 4-dimethylaminophenyl or 4-diethylaminophenyl, styryl, substituted styryl such as 4-hydroXystyryl, 3,4-dihydroxystyryl, 4-methoxystyryl, 3,4-dimethoxystyryl or 4-dirr1ethylaminostyryl, naphthyl or furyl;
  • R3, R5, R6, R7 each is H, aliphatic group such as methyl or ethyl, alkoxy group such as methoxy or ethoxy, hydroxy group, or aryl group such as phenyl or 4- methoxyphenyl;
  • R4 is aryl group such as phenyl, 4-hydroxyphenyl or 4-methoxyphenyl, H, or aliphatic group such as styryl, alkoxystyryl or hydroxystyryl;
  • anion is anionic function selected from the group consisting of uoborate, chloride and perchlorate.
  • the preferred benzopyrylium salts are prepared generally by one of four methods.
  • a lirst method (a modidication of a method disclosed at J. Chem. Soc., 1935, p. 941) is based on the reaction of a phenol or phenol derivative with a -dicarbonyl compound or a,-unsaturated ketone in the presence of hydrogen chloride, sulfuric acid, ferric chloride or phosphorus pentachloride in solution of acetic or formic acid.
  • a second method comprises using an intermediate product prepared from a phenol and a coumarin derivative in the presence of phosphorus oxychloride or zinc chloride (a similar Way to that disclosed at Helv. Chim, acta, 34, p. 1761 (1950)).
  • a third method (based on a method disclosed at I. Amer. Chem. Soc., 74, p. 3445 (1952)) is achieved by ring closure of an unsaturated ketone derivative prepared from an o-hydroxybenzaldehyde With a carbonyl compound in the presence of an alkali so as to form a benzopyrylium ring.
  • the benzopyrylium ring is incorporated with an ethenyl radical by the reaction of active a-methylene radical in the 2-position of 2-alkylbenzopyrylium with an aromatic aldehyde.
  • a fourth method (based n a method disclosed at I, Chem. Soc., 1929, p. 936) is achieved in one step by both ring closure reaction and ethenylation reaction of an aromatic aldehyde With an unsaturated ketone derivative prepared from an o-hydroxybenzaldehyde with a carbonyl compound in the presence of an alkali.
  • the precipitated benzopyrylium salt is then collected by ltration, washed thoroughly with ether and dried at a reduced pressure ranging from 2 to 10 mm. Hg. Recrystallization from nitrobenzene gives 5 grams of metallic lustrous needles which melts about 250 C. while darkening gradually. The needles give a red solution in dichloroethane.
  • the obtained crude product is recrystallized twice from a solvent consisting of three weight parts of methanol and one weight part of dichloroethane to yield 3 grams of lustrous needles, having a melting point of 228 to 229 C.
  • the needles give a reddish violet solution in dichloroethane.
  • the compounds listed in Table 1 are sensitizing agents which can improve the photoconductivity and the spectrum characteristics of poly-N-vinylcarbazole, poly-3,6- dibromo-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyacenaphthylene and polyvinylanthracene.
  • These polymers, except brominated poly-N-vinylcarbazole, 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 is added 18.44 grams of N-bromosuccinimide and 0.173 gram of benzoyl peroxide. The mixture is heated at C. for 2 hours while being stirred thoroughly, after which it is poured into methanol to obtain a white polymer. The white 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.
  • the novel sensitizer comprising at least one compound from the group listed in Table 1 is dissolved in a suitable solvent, such as methanol, ethanol, dichloroethane, methylene chloride, chloroform, or a combination thereof, and is added to the solution of the photoconductive polymer described above.
  • a suitable solvent such as methanol, ethanol, dichloroethane, methylene chloride, chloroform, or a combination thereof.
  • the amount of the sensitizer added is from 0.01 to 2.0 weight parts to weight parts of the photoconductive polymer. Preferable amount thereof is from 0.1 to 2.0 weight parts to 100 weight parts of the photoconductive polymer.
  • a said solution of the photoconductive polymer and the benzopyrylium salt in a suitable solvent is applied to the supports in the usual manner, for example, by spraying, by direct application, by means of blade coating, by means of whirler coating, etc., and then dried so as to produce a homogenous photoconductive insulating layer on the electroconductive support.
  • Operable solvents are benzene, toluene, chlorobenzene, dioxane, methylene chlorides, 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 rosin, 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 foils made of electrically conductive resins or coated with evaporated thin metal layer.
  • the transparent support can produce a transparent electrophotographic plate, foil or lm. 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 electrophotographic methods 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 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 xed by heating at about C. From positive masters, positive images characterized by good contrast are produced.
  • the benzopyrylium salts polymerize N-vinylcarbazole or 3,6-dibromo-N-vinylcarbazole for obtaining a high polymer.
  • N-vinylcarbazole which is dissolved in milliliters of dichloroethane
  • Z-(a-isopropylw-phenylbutadienyl)benzopyrylium perchlorate which is dissolved in 0.1 milliliter of dichloroethane.
  • the solution is poured into methanol.
  • the poly-N-vinylcarbazole obtained as a white precipitate has a. molecular Weight of a million and is prepared in a 98 weight percent yield.
  • 3,6-dibromo-N-vinylcarbazole can be treated by the same procedure as mentioned above and is obtained as a white polymer in a high yield.
  • the other benzopyrylium salts can be similarly used as an initiator of N-vinylcarbazole or 3,6dibromo-N-vinylcarbazole polymerization.
  • the benzopyrylium salts discovered according to the invention can be -used as a sensitizing agent and as an initiator of polymerization.
  • Such two abilities make it possible to prepare an electrophotographic layer in the following manner: To a solution of 1 gram of 3,6-dibromo-N-vinylcarbazole dissolved in 10 milliliters of methylene chloride is added 0.001 gram of 2-(a-isopropylw-phenylbutadienyl -6-7-dimethylbenzopyrylium perchlorate which is dissolved in 0.1 milliliter of methylene chloride. After standing at 25 C. for an hour, the solution is directly applied to an aluminum plate by means of blade coating. Thus, an electrophotographic plate improved in the photosensitive properties can be easily obtained.
  • more preferable electrophotographic materials can be prepared by a combination of brominated poly-N-vinylcarbazole and, as benzopyrylium salt, at least one compound selected from the group consisting of 2-(a-isopropyl-w-phenylbutadienyl)benzopyrylium perchlorate,
  • more preferable electrophotographic material can be prepared by a cornbination of poly-3,6-dibromo-N-vinylcarbazole and, as benzopyrylium salt, at least one compound selected from the group consisting of 2-(oc-isopropyl-w-phenylbutadienyl)benzopyrylium perchlorate,
  • EXAMPLE 1 1 gram of poly-N-vinylcarbazole and 0.004 gram of a benzopyrylium salt listed in Table 1 are dissolved in 10 milliliters of methylene chloride. The solution is applied to an aluminum plate by means of blade coating and is dried to form a layer of 10a in thickness. After the said aluminum plate provided with the layer is charged positively by means of corona discharge with a charging device maintained at approximately 6000 volts in the dark, it is placed under a positive master and is exposed to a W. tungsten lamp at an illumination of 50 luxes, and the said plate is powdered over with a developer in a per se known manner. This developer consists of toner and carrier.
  • the toner consists of a low .melting-point polystyrene, colophony and carbon-black.
  • the toner is mixed with a carrier substance having such nature that the toner becomes triboelectrically charged with a charge opposite to that produced on the plate.
  • a positive image is produced and is xed by slight heating.
  • Table 3 are shown the optimum amounts of exposure in lux-second units.
  • EXAMPLE 3 l gram of brominated poly-N-vinylcarbazole and 0.1 gram of chlorinated aliphatic acid ester (commercially available as Adecasizer S3), 0.2 gram of epoxy resin (commercially available as Epon 828), 0.5 gram of polycarbonate resin (commercially available as Panlite-C) and 0.003 gram of a benzopyrylium salt listed in Table 1 are dissolved in a mixed-solvent of 8 milliliters of chlorobenzene and 2 milliliters of dichloroethane.
  • EXAMPLE 4 1 gram of polyacenaphthylene and 0.6 gram of chlorinated diphenyl and 0.005 gram of a benzopyrylium salt listed in Table 1 are dissolved in 10 milliliters of dichloroethane. The solution is applied to an aluminum plate by means of whirler coating and is dried to form a layer of 4p in thickness. An electrophotographic image is produced in a similar way to that described in Example 1. Table 6 shows the optimum amounts of exposure in luxsecond units to reproduce exactly the original images.
  • An electrophotographic material comprising a conductive support layer and a photoconductive insulating layer, the latter comprising a combination of a photoconductive polymeric compound and a sensitizer having the following chemical formula Anion- R5- ⁇ /R3 wherein R1 is H, phenyl or alkyl;
  • R2 is phenyl, hydroxyphenyl, biphenyl, alkoxyphenyl, aminophenyl, styryl, substituted styryl, naphthyl or furyl;
  • R3, R5, R6, R7 each is H, styryl or substituted styryl
  • R4 is aryl, H, or alkyl
  • anion is anionic function selected from the group consisting of uoborate, chloride and perchlorate;
  • said photoconductive polymeric compound comprising at least one compound selected from the group consisting of poly-N-vinylcarbazole, poly-3,6-dibromo-N-vinylcarbazole, brominated poly-N-vinylcarbazole, polyacenaphthylene and polyvinylanthracene.
  • R1 is selected fro-m the ⁇ group consisting of H, phenyl, methyl, ethyl, propyl, isopropyl, butyl or tertiary butyl;
  • R2 is selected from the group consisting of phenyl, 4- biphenyl, 2-hydroxyphenyl, 4-hydroxyphenyl, 3,4-dihydroxyphenyl, 4-methoxyphenyl, 3,4-dimethoxyphenyl, 4-dimethylaminophenyl, 4-diethylaminophenyl, styryl, 4-hydroxystyryl, 3,4-dihydroxystyryl, 4-methoxystyryl, 3,4-dimethoxystyryl, 4-dimethylaminostyryl, naphthyl and furyl;
  • R3, R5, R6, R are selected from the group cosnisting of H, methyl, ethyl, methoxy, ethoxy, hydroxy, phenyl, 4-methoxyphenyl;
  • R4 is selected from the group consisting of phenyl, 4- hydroxyphenyl, 4-methoxyphenyl, H, styryl, alkoxystyryl, and hydroxystyryl;
  • the anion is selected from the group consisting of fluolborate, chloride and perchlorate.
  • sensitizer comprises at least one compound selected from the group consisting of 2-(a-isopropyl-w-phenylbutadienyl)benzopyrylium perchlorate,
  • An electrophotographic material according to claim 3, wherein said combination comprises weight parts of photoconductive polymeric compound and 0.01 to 2.0 weight parts of sensitizer.
  • An electrophotographic material is a combination of 100 weight parts of poly-3,6-dibromo-N-vinylcarbazole and 0.01 to 2.0 Weight parts of a sensitizer, said sensitizer comprising at least one compound selected from the group consisting o-f 2- -isopropyl-w-phenylbutadienyl) -benzopyrylium perchlorate,

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US636172A 1966-07-18 1967-05-04 Electrophotographic material Expired - Lifetime US3526502A (en)

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3617268A (en) * 1969-01-30 1971-11-02 Matsushita Electric Ind Co Ltd Electrophotographic materials
US3658521A (en) * 1969-10-03 1972-04-25 Eastman Kodak Co 1-aminopyridinium dyes as sensitizers in electrophotographic layers
US3770428A (en) * 1970-08-25 1973-11-06 Xerox Corp PHOTOCONDUCTIVE REACTION PRODUCT OF N -beta- CHLORETHYL CARBAZOLE AND FORMALDEHYDE
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
US3907561A (en) * 1972-10-06 1975-09-23 Ricoh Kk Pyronyl-pyrylium sensitizers for electrophotographic organic photoconductors
US3912508A (en) * 1970-10-07 1975-10-14 Matsushita Electric Ind Co Ltd Electrophotographic element comprising an organic photoconductive layer sensitized locally at its surface
USRE28698E (en) * 1970-03-13 1976-01-27 Matsushita Electric Industrial Co., Ltd. Electrophotographic material containing sensitizers
US3938994A (en) * 1972-03-17 1976-02-17 Eastman Kodak Company Pyrylium dyes for electrophotographic composition and element
US3953433A (en) * 1971-06-22 1976-04-27 Ricoh Co., Ltd. Sensitizer for use in electrophotographic light-sensitive material
US5405976A (en) * 1990-11-21 1995-04-11 Polaroid Corporation Benzpyrylium squarylium and croconylium dyes, and processes for their preparation and use
US5977351A (en) * 1990-11-21 1999-11-02 Polaroid Corporation Benzpyrylium squarylium and croconylium dyes, and processes for their preparation and use

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3580616A4 (de) * 2017-06-28 2020-05-06 HP Indigo B.V. Flüssige elektrostatische tintenentwickleranordnung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB964875A (en) * 1959-02-26 1964-07-22 Gevaert Photo Prod Nv Improvements in or relating to electrophotography
US3250615A (en) * 1961-10-23 1966-05-10 Eastman Kodak Co Light-sensitive layers containing pyrylium and thiapyrylium salts

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB964875A (en) * 1959-02-26 1964-07-22 Gevaert Photo Prod Nv Improvements in or relating to electrophotography
US3250615A (en) * 1961-10-23 1966-05-10 Eastman Kodak Co Light-sensitive layers containing pyrylium and thiapyrylium salts

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3617268A (en) * 1969-01-30 1971-11-02 Matsushita Electric Ind Co Ltd Electrophotographic materials
US3658521A (en) * 1969-10-03 1972-04-25 Eastman Kodak Co 1-aminopyridinium dyes as sensitizers in electrophotographic layers
USRE28698E (en) * 1970-03-13 1976-01-27 Matsushita Electric Industrial Co., Ltd. Electrophotographic material containing sensitizers
US3770428A (en) * 1970-08-25 1973-11-06 Xerox Corp PHOTOCONDUCTIVE REACTION PRODUCT OF N -beta- CHLORETHYL CARBAZOLE AND FORMALDEHYDE
US3912508A (en) * 1970-10-07 1975-10-14 Matsushita Electric Ind Co Ltd Electrophotographic element comprising an organic photoconductive layer sensitized locally at its surface
US3953433A (en) * 1971-06-22 1976-04-27 Ricoh Co., Ltd. Sensitizer for use in electrophotographic light-sensitive material
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
US3938994A (en) * 1972-03-17 1976-02-17 Eastman Kodak Company Pyrylium dyes for electrophotographic composition and element
US3907561A (en) * 1972-10-06 1975-09-23 Ricoh Kk Pyronyl-pyrylium sensitizers for electrophotographic organic photoconductors
US5405976A (en) * 1990-11-21 1995-04-11 Polaroid Corporation Benzpyrylium squarylium and croconylium dyes, and processes for their preparation and use
US5627014A (en) * 1990-11-21 1997-05-06 Polaroid Corporation Benzpyrylium squarylium and croconylium dyes, and processes for their preparation and use
US5977351A (en) * 1990-11-21 1999-11-02 Polaroid Corporation Benzpyrylium squarylium and croconylium dyes, and processes for their preparation and use

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DE1572354B2 (de) 1974-03-14
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DE1572354C3 (de) 1974-10-17

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