Classifications

• • 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
  • G03G5/05—Organic bonding materials; Methods for coating a substrate with a photoconductive layer; Inert supplements for use in photoconductive layers
  • G03G5/0528—Macromolecular bonding materials
  • G03G5/0557—Macromolecular bonding materials obtained otherwise than by reactions only involving carbon-to-carbon unsatured bonds
  • G03G5/0575—Other polycondensates comprising nitrogen atoms with or without oxygen atoms in the main chain

Definitions

• Electro-photographic recording material wherein the photoconductive substance, preferably photoconductive zinc oxide, is dispersed in a binder containing at least 60% by weight of a hydantoin-formaldehyde condensation polymer and characterized by rapid regain of its dark-resistivity so as to be specially adapted for rapid repetitive charging and exposure.
• the photoconductive substance preferably photoconductive zinc oxide
• This invention relates to recording members suited for used in electrophotography.
• Photoconductive binder type coatings prepared by incorporating a finely divided photoconductor in a binder are well known.
• various inorganic as well as organic substances can be incorporated as photoconductive substances, e.g. sulphur, selenium, the oxides, sulphides and selenides of zinc, cadmium, titanium, mercury, antimony, bismuth and lead, anthracene, anthraquinone and more recently discovered organic monomeric and polymeric organic photoconductors, such as e.g. those described in the Belgian patent specifications 587,300, the UK.
• the photoconductive binder coatings are prepared by dispersing or dissolving the photoconductive substances in an organic solution of an insulating binder, and by applying them as such in the form of a layer to an apporpriate relatively conductive support.
• a photoconductive recording element having interesting properties for recording electromagnetic radiation images can be prepared by a method comprising the step of dispersing an inorganic photoconductive substance e.g. photoconductive zinc oxide in a hydantoin-formaldehyde condensate, the structural units of which correspond to the following formula:
• each of R and R represent hydrogen or a lower alkyl radical (C1C7).
• the intrinsic viscosities of the said polymers preferably ranges between 0.02 and 0.20, measured in a mixture of water and technical concentrated ammonia (25%) in a ratio 9: 1.
• a recording layer coated from the above-mentioned dispersion is characterized by a quick and high chargeability and a high sensitivity even without spectral sensitizing agent(s).
• the hydantoinformaldehyde resin is preferably applied from an aqueous medium which offers all the advantages associated with the absence of organic solvents in the coating composition and requires no special coating techniques.
• the coating medium is preferably made alkaline and for that purpose preferably a volatile base (boiling point below C.) is used e.g. ammonia. It was experimentally stated that a coating composition with a pH above 7 yields recording layers with a relatively soft gradation; see therefore Example 3.
• the recording element prepared according to the present invention possesses the property of regaining rapidly, after charging and exposure, its original dark-resistivity so that this element is very suited for multicolour reproduction wherein generally at least two successive chargings and exposures of the element are required.
• the recording element prepared according to the present invention is flexible, possessess a very good mechanical strength and shows a sufficient adhesion to a paper support as well as to a metal support, e.g., an aluminium support.
• the resistance of the photoconductive coatings according to the present invention to non-polar organic solvents is high, so that by virtue of this property the recording layers are very well suited for electrophotographic reproduction techniques wherein an insulating hydrocarbon liquid containing charged pigment particles is used (electrophoretic development).
• the order of mixing steps for the constituents to form the coating is not important.
• the kind of photoconductor does not play a part, e.g. any known inorganic photoconductor may be used.
• the quantitative ratios of the photoconductive substances to the binding agents may vary between wide limits.
• Other binding agents applicable from an aqueous alkaline medium are, e.g., those described in the United Kingdom patent specifications 888,371; 932,730; 938,366 and 881,613, the publ. Dutch patent applications 6608815 and 6608814 and in US. patent specification 2,959,481.
• the photoconductive substance in a ratio of 1 part by weight to 0.2 to 1.5 parts by weight of the total content of binder.
• the thickness of the photoconductive layer may vary between wide limits according to the requirements of each case. Good recording and reproduction results are obtained with electrophotographic layers with 15 to 25 g. of photoconductive substance per square meter. Too thin layers possess an insufiicient insulating power, whereas too thick layers possess undesirable mechanical properties.
• the photoconductive recording layers prepared according to the present invention may contain, in addition to the photoconductive substance(s) and hydantoin-formaldehyde binder, acid compounds for increasing the darkresistivity as described e.g. in UK. patent specification 1,020,504 and Belgian patent specification 612,102 and additives known in coating techniques, e.g., dispersing agents and compounds of influencing the gloss and/or the viscosity, and compounds which counteract ageing and/or oxidation of the layers, or which influence the thermal stability of the layers.
• additives known in coating techniques e.g., dispersing agents and compounds of influencing the gloss and/or the viscosity, and compounds which counteract ageing and/or oxidation of the layers, or which influence the thermal stability of the layers.
• the spectral sensitization of the materials prepared according to the present invention is advantageously performed by means of the sensitizing dyes mentioned in the U.K. patent specification 1,020,504, and in the publ.
• Dutch patent application 6704706 and pub Dutch patent application 6717400.
• the sensitizing dyes are preferably applied according to a sensitizing techique described in the publ.
• Dutch patent application 6704768 The sensitizing dyes are preferably applied according to a sensitizing techique described in the publ. Dutch patent application 6704768.
• the photoconductive coating composition according to the present invention may be coated on a support by a known coating technique e.g. by spraying, whirling, dipcoating or by a coating technique wherein use is made of a doctor blade.
• the supports or base materials are chosen in view of the particular charging, exposing, recording, developing and/ or transfer technique wherein the recording material is to be used. Any support suited for use in electrophotographic materials is here included.
• As paper supports having no pre-coat preferably glassine type paper sheets are used.
• the support has preferably an electric volume resistivity considerably lower than that of the recording layer, preferably has a volume resistivity of at least times less than that of the recording layer.
• Suitable supports are described, e.g., in UK. patent specifications 1,020,504 and 995,491 and in US. patent specification 3,008,825.
• Recording elements according to the present invention are also suited for recording light images without it being necessary to non-differentially charge the recording element beforehand, which means that sufliciently high concentrated technical ammonia (9:1) as dispersing agent and 0.62 cc. of acid butylphosphate as a 10% by weight solution in ethanol.
• the obtained slurry was then sub jected for 15 min. to high speed stirring with a Kothofi' mixing sirene.
• the pH of the dispersion was measured and the value 6.9 noted.
• the zinc oxide dispersion was coated onto a glassine type paper at a rate of 20 g. per sq. m., dried and stored in the dark for 24 hours.
• the exposed layer was developed with an electrophoretic developer.
• the maximum density obtained was 0.8 and the minimum density 0.18.
• the number of blackened steps between the maximum density and minimum density being a measure for the gradation was 3.
• the number of steps which were not covered with developing substances being a measure of the light-sensitivity of the recording layer was 7.
• Example 1 was repeated but instead of the dimethylhydantoin-formaldehyde resin at same amount of a hydantom-formaldehyde resin having an intrinsic viscosity of 0.08 measured in a mixture of Water and technical concentrated ammonia (25%) in a ratio 9:1 was used.
• Example 1 was repeated but various amounts of ammonia used in order to raise the pH of the dispersion values between 6.9 and 11.1. The highest amount of technical ammonia (25% by weight) necessary was 6 cc. The different compositions were separately coated and developed in the same manner as in Example 1.
• the photographic results are listed in the following table.
• the sensitivity is expressed by the number of nonblackened steps; the higher that number the more sensitive the recording layer.
• the gradation is expressed by the number of blackened steps between maximum and minimum optical density; the higher that number the softer the gradation.
• EXAMPLE 1 To a solution of 12 g. of dimethylhydantoin-formaldehyde resin (the intrinsic viscosity of said resin measured in a mixture of water and technical concentrated ammonia (25%) in a ratio 9:1, is 0.04) in cc. of water, 15 g. of photoconductive zinc oxide (French Process type) were added and subsequently during slowly stirring 0.75 cc. of a 10% by weight solution of copoly(maleic anhydride/N-vinylpyrrolidone) 40) in a mixture of water/ What we claim is:
• a recording material which comprises a support and a recording layer containing a photo-conductive substance dispersed in a binder containing at least 60% by weight of a hydantoin-formaldehyde condensate the structural units of which correspond to the following formula:
• each of R and R is hydrogen or lower alkyl radical of 1-5 carbon atoms.
• a recording material according to claim 1, wherein the photoconductive substance is photoconductive zinc oxide.
• a recording material according to claim 1, wherein the support is a glassine type paper support.
• a recording material according to claim 5 wherein GEORGE LESMES, Primary EXamineI the Said medium iS alkall'lle- J. R. MILLER, Assistant Examiner 7.

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• Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Spectroscopy & Molecular Physics (AREA)
• General Physics & Mathematics (AREA)
• Photoreceptors In Electrophotography (AREA)

Applications Claiming Priority (1)

Publications (1)

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ID=9873604

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (1)

• 1967
  • 1967-02-28 GB GB9522/67A patent/GB1198995A/en not_active Expired
• 1968
  • 1968-02-24 DE DE19681622343 patent/DE1622343A1/de active Pending
  • 1968-02-27 US US708505A patent/US3597195A/en not_active Expired - Lifetime
  • 1968-02-27 NL NL6802733A patent/NL6802733A/xx unknown
  • 1968-02-28 BE BE711376D patent/BE711376A/xx unknown

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