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
  • G03G5/06—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
  • G03G5/0642—Heterocyclic compounds containing one hetero ring being more than six-membered
• • 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
  • G03G5/0633—Heterocyclic compounds containing one hetero ring being five-membered containing three hetero atoms
• • 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
  • G03G5/064—Heterocyclic compounds containing one hetero ring being six-membered containing three hetero atoms
• • 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
  • G03G5/0664—Dyes
  • G03G5/0666—Dyes containing a methine or polymethine group
  • G03G5/0668—Dyes containing a methine or polymethine group containing only one methine or polymethine group
  • G03G5/067—Dyes containing a methine or polymethine group containing only one methine or polymethine group containing hetero 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
  • G03G5/09—Sensitisors or activators, e.g. dyestuffs

Definitions

• Electrophotographic recording material containing photoconductive zinc oxide treated with urazole or one of its derivatives and processes of electrophotographic recording using such materials. These materials are characterized by low-memory effect, improved charging characteristics and are capable of accepting either positive or negative charges to obtain either positive or negative copies.
• This invention relates to light-sensitive recording materials comprising as light-sensitive substance a photoconductor.
• Photoconductive binder-type coatings prepared by incorporating a finely divided photoconductor in a binder are well known.
• electrophotographic materials containing a photoconductive layer comprising photoconductive zinc oxide dispersed in an insulating binder. Said layer is coated on a sufficiently conductive support, e.g., a clay-coated or glassine-type paper base from a paintlike coating mixture by conventional paper coating techniques. Since the zinc oxide has a brilliant white color it forms an excellent base for contrasting with the developer materials applied to it. Moreover zinc oxide is relatively less expensive and can be spectrally sensitized by a great variety of dyes. However, as already explained in the United Kingdom Pat. No. 1,020,504 filed Dec. 29, 1961 by Gevaert Photo-Producten N.V., zinc oxide possesses the less interesting property of having a relatively low dark-resistivity.
• a binding agent is used improving the dark-resistivity of the recording layer.
• zinc oxide is treated with certain organic phosphorous compounds, preferably organic oxyacids of phosphorus improving the dark-resistivity of the photoconductive zinc oxide grains.
• organic phosphorous compounds preferably organic oxyacids of phosphorus improving the dark-resistivity of the photoconductive zinc oxide grains.
• the memory effect is expressed here by the ratio of the periods of time (1 and t respectively) elapsing before by electrostatic corona charging in the absence of light 90 percent of the maximal charge level is attained on a photoconductive recording layer that has not been exposed previously (time 1,), respectively 90 percent of the maximal charge level is attained on the same photoconductive recording layer (time t that immediately before its charging had received an exposure to active light sufiicient to remove a charge that has been applied in a previous step.
• the present invention is based on the discovery that the treatment of photoconductive zinc oxide with a compound (treating agent) corresponding to the following general formula (including its salt and tautomeric structures):
• each of R, and R represents hydrogen, an alkyl group including a substituted alkyl group, an aryl group including a substituted aryl group, an acyl group including a substituted acyl group, e.g., an aliphatic acyl group (alcoyl) or substituted aliphatic acyl group, e.g., an acetyl group, or an aromatic acyl group (aroyl), e.g., a benzoyl group, including a substituted aromatic acyl group, or a heterocyclic nucleus including a substituted heterocyclic nucleus, e.g., a pyridine nucleus, or a thiazole nucleus, or R and R together represent the necessary atoms to close a fused ring or ring system,
• X represents oxygen or imino
• at least one of the nitrogen atoms making part of the ring closed by Z carries a hydrogen atom, that optionally may be replaced by a cation when using the compound in salt form, increases the dark-resistivity of a recording layer containing such zinc oxide and gives rise to a small memory effect.
• the said treatment improves the chargeability of a photoconductive recording layer containing photoconductive zinc oxide with a negative corona and moreover besides the possibility of negative corona-charging offers the unexpected possibility of positively corona-charging the recording layer and obtaining thereon positive electrostatic charge images.
• Z represents a group, wherein R represents hydrogen or a hydrocarbon radical, e.g., an alkyl radical including a substituted alkyl radical or an aryl radical including a substituted aryl radical, and X represents oxygen or imino.
• R represents hydrogen or a hydrocarbon radical, e.g., an alkyl radical including a substituted alkyl radical or an aryl radical including a substituted aryl radical
• X represents oxygen or imino.
• Most preferred compounds according to said general formula are urazole and urazole derivatives wherein at least one nitrogen atom in the ring carries a hydrogen atom.
• the property of the recording material according to the present invention of being capable to be charged positively as well as negatively, it is possible with one and the same developer, e.g., an electrophoretic developer with toner particles possessing a particular sign of charge, to reproduce one and the same original at will as a positive or negative copy depending on the sign of the electrostatic charge applied to the recording layer of said recording material.
• an electrophoretic developer with toner particles possessing a particular sign of charge e.g., an electrophoretic developer with toner particles possessing a particular sign of charge
• the photoconductive zinc oxide is mixed with other photoconductive substances, e.g., the photoconductive chalkogenides of cadmium more particularly photoconductive cadmium sulphide, crystalline mixed cadmium sulphide selenide and cadmium selenide.
• the said chalkogenides may be doped, e.g., with zinc in order to increase their photosensitivity.
• a small memory effect of the recording material is advantageous in cases in which the recording material before its image-wise exposure accidentally or not is overall-exposed to daylight or in which the recording material has to be used in a multicolor reproduction system, wherein the recording layer is several times successively charged and exposed, e.g., through halftone selection transparencies of the multicolor original to be reproduced.
• the recording material is to be tested is fixed onto a rotating disk whereon it is successively carried under a corona charging unit and under a probe or electrode, wherein a charge is induced being directly proportional to the one present on the recording layer (ref. Cassiers, J. Phot. Sci., 10 1962) 58).
• the time (t,) of reaching percent of the maximal charge level is noted and then the recording material after maximal charging is exposed till complete discharging. Practically immediately thereafter charging is repeated and again the time is noted for reaching 90 percent of the second maximal level which normally is not as high as the one obtained in the first charging step.
• a usual rotating speed of the disk is 750 or complexated form or its tautomeric configuration. since also in these forms an interaction with the photoconductive zinc oxide probably forming a zinc salt can take place.
• the treating agent is r.p.m.
• Treating agents which have proved to be particularly useful 5 preferably contacted in dissolved form with the photoconducare listed hereafter. g 93 jS E;
• the treating agent can also be applied in the salt
• the present invention can be carried out in the manufacture of an electrophotographic recording material, by allowing the zinc oxide to come into contact with the treating agent at any stage of the manufacture.
• the contact can take place before or during the preparation of a photoconductive coating composition, comprising photoconductive zinc oxide and a binder material, for forming a photoconductive layer.
• the contact can take place after the formation of the layer, e.g., after coating a said compound onto a support.
• an electrographic record- 'ing material according to the invention need not comprise only zinc oxide particles which have been treated in accordance with the invention.
• the photoconductive layer can incorporate a mixture of treated and untreated zinc oxide grains. Some of the zinc oxide grains can be treated as described in the United Kingdom Pat. No. 1,020,504 filed Dec. 29, 1961 and Pat. No. 1,020,505 filed Nov. 8, 1961 bothby Gevaert Photo-Producten N.V.
• the treating agent is added to an aqueous dispersion of the photoconductive zinc oxide.
• the treated zinc oxide is filtered off or centrifuged, dried and then dispersed in a solution of binding agent. This method is especially suited for compounds that are soluble or dispersible in water.
• the photoconductive zinc oxide is dispersed in an organic solvent wherein the treating agent is soluble or dispersie w e svizqn t e necessary ay"? 9f FWFFEEJLB P. i added.
• a binding agent can be applied simultaneously or thereafter.
• the photoconductive zinc oxide, a binding agent and a solvent for the latter are dispersed together, e.g., by grinding in a ball-mill, according to the particular zinc oxide particle size desired.
• the treating agent is added before, during or after grinding.
• a layer is applied from a composition containing the treating agent and optionally a binding agent.
• the treating agent is incorporated into the paper, e.g., during the manufacture of the paper.
• a layer is applied containing untreated zinc oxide and a binding agent.
• some treating agent diffuses from the first layer or the paper backing, to the photoconductive zinc oxide and is absorbed thereon.
• the agent can be used in such an amount that a sufficient quantity thereof remains in the paper to render the latter sufficiently conductive for carrying off electrostatic charges during exposure.
• a layer of untreated photoconductive zinc oxide which is dispersed in a binding agent.
• a layer is applied containing the treating agent and a binding agent if desired.
• some treating agent diffuses from the second layer to the zinc oxide in the first layer.
• the composition of the second layer can be selected so as to impart required surface characteristics to the recording material, e.g., to render the surface suitable for application of the developing processes described and claimed in the United Kingdom Pat. No. 1,020,502 and 1,020,505 both filed Nov. 8, 1961 by Gevaert Photo-Producten N.V.
• the photoconductive zinc oxide is preferably prepared by the oxidation of zinc vapor, thus is preferably so-called French-type photoconductive zinc oxide.
• the dark-resistivity of a photoconductive zinc oxide layer can be increased to an optimum value by using increasing quantities of treating agents. If the amount of treating agent, which gives an optimum dark-resistivity, is exceeded, the latter decreases proportionally to the amount of excess treating agent.
• the required proportion of the treating agent in relation to the photoconductive zinc oxide generally is higher than when the treating agent is incorporated into the zinc oxide layer itself.
• the ratio of binding agent to photoconductor influences the quality of the photoconductive layer with respect to the photoconductive properties, mechanical strength and insulating power. It is preferred to employ the binding agent(s) and photoconductor in weight ratio of from 1:3 to 1:9. If layers are used with a much larger proportion of binding agent, the image sharpness tends to decrease. if layers are used with much lower content of binding agent than the minimum content specified above, the mechanical strength of the coating may be insufficient for many purposes.
• Photoconductive recording materials according to the present invention can be used in a wide variety of reproduction methods, and enable very contrasty images to be easily and consistently obtained, even under widely difiering circumstances such as strongly varying degrees of air humidity.
• binding agents possessing a higher specific dark-resistivity than the treated zinc oxide as well as binding agents possessing a lower specific dark-resistivity can be used.
• Suitable binding agents are described in the United Kingdom Pat. No. 964,878 filed May 3, 1960 and Pat. No. 1,020,054 filed Dec. 6, 1962 both by Gevaert Photo-Producten NV.
• the said treating agents are successfully used in combination with binding agent(s) applied from an organic medium as well as in combination with binding agents applied from an aqueous medium.
• Binding agents and mixtures of binding agents suitable to be applied from an aqueous medium are described in out published Dutch Pat. Application Nos. 6,608,814 and 6,608,815 both filed June 24, 1966 and 6,802,733 filed Feb. 27, 1968 Binding agents and mixtures of binding agents applied from an organic medium are, e.g., described in the United Kingdom Pat. No. 1,020,503 filed Nov. 8, 1961 and Pat. No. 1,020,504 filed Dec. 29, 1961 both by Gevaert Photo-Producten N.V.
• Preferred binding agents contain acidic groups or groups from which an acid can be produced in situ.
• the content of acidic groups is, however, preferably not so high that the recording layer obtains a water-soluble character.
• vinyl copolymers that contain organophilic (hydrophobic) structural units and acidic structural units derived from a, ,B-ethylenically unsaturated carboxylic acid compounds, e.g., crotonic acid, acrylic acid, maleic acid, itaconic acid and methacrylic acid compounds.
• organophilic (hydrophobic) structural units and acidic structural units derived from a, ,B-ethylenically unsaturated carboxylic acid compounds e.g., crotonic acid, acrylic acid, maleic acid, itaconic acid and methacrylic acid compounds.
• Hornopolymers containing acidic structural units may be used in admixture with organophilic polymers.
• Polymers and copolymers from which acidic groups can be produced in situ contain, e.g., carboxylic anhydride groups, e.g., maleic anhydride groups and/or sulphonylchloride groups, which can be hydrolized to sulphonic acid groups.
• the photoconductive zinc oxide is preferably dispersed in an organic medium (aromatic hydrocarbon so1vent(s), chlorinated hydrocarbon solvent(s) or lower aliphatic alcohol) by means of an acidic alkyd resin, copo1y(ethylene/vinyl-sulphonyl chloride/vinyl chloride) or formaldehyde acetal of polyvinyl alcohol respectively.
• organic medium aromatic hydrocarbon so1vent(s), chlorinated hydrocarbon solvent(s) or lower aliphatic alcohol
• binding agents and binding agent mixtures for application in recording layers according to the present invention are:
• poly(isobutyl methacrylate) 4. copoly( methyl methacrylate/isobutyl 1ate)(20/80 by weight) 5.
• poly(isobutyl methacrylate) b. formaldehyde-acetal of polyvinyl alcohol 6. copoly(vinyl acetate/crotonic acid) (94.6/5.4 percent by weight) methacrya. copoly(vinyl acetate/crotonic acid) (93.4/6.6 percent by weight) b. copoly(ethylene/vinylsulphonyl chloride/vinyl chloride) (45 .2/6.2/48.6 percent by weight) a.
• styrolated alkyd resin b. copoly(vinyl chloride/vinyl acid)(86.5/l3.3/0.2 percent by weight) 10. copoly(vinyl acetate/methyl acrylate/acrylic acid) (87/12/1 percent by weight) 1 l. copoly(styrene/methyl acid)(55/44.6/0.4 percent by weight)
• the treating agents applied in the present invention do not exclude the increase of photosensitivity of the recording element, e.g., by spectral sensitization of the photoconductive zinc oxide.
• the spectrally sensitizing dyes can be allowed to adsorb to the photoconductive zinc oxide before, during and/or after the dark-resistivity increasing treatment.
• Spectral sensitizing agents which can be applied are described in the already mentioned United Kingdom Pat. No. 1,020,504 and in our published Dutch Pat. application Nos. 6,717,400 filed Dec. 20, 1967, 6,805,983 filed Apr. 26, 1968 No. 6,704,706 filed Apr. 3, 1967 and No. 6,704,768 filed Apr. 4, 1967.
• a very suitable technique for applying the spectral sensitizing agents is described in the published Dutch Patent application No. 6,704,768 which technique can also be applied successfully in respect of the dark-resistivity increasing compounds used according to the present invention.
• the photoconductive recording layers containing a treating agent for photoconductive zinc oxide as described may contain in addition to the photoconductive substance and binder any other type of dark-resistivity or sensitivity increasing compound, e.g., the phosphorous compounds and other dark'resistivity increasing compounds described in the Belgian Pat. No. 612,102 filed Dec. 29, 1961 by Gevaert Photo-Producten N.V., and additives known in the coating techniques, e.g., dispersing agents (see, e.g., our published Dutch Pat. application No. 6,712,156 filed Sept. 5, 1967), compounds influencing the gloss and/or the wear resistance of the coating, and, compounds that counteract aging and/or oxidizing of the;
• any other type of dark-resistivity or sensitivity increasing compound e.g., the phosphorous compounds and other dark'resistivity increasing compounds described in the Belgian Pat. No. 612,102 filed Dec. 29, 1961 by Gevaert Photo-Producten N.V.
• acetate/acrylic acrylate/acrylic layer or that influence the thermal stability.
• preference is given to those which least reduce the sensitivity and dark-resistivity of the photoconductive layer.
• the photoconductive composition treated according to the present invention may be coated on a support according to a known coating technique, e.g., by spraying, whirling, dip-coating, or by a coating technique wherein use is made of a doctor blade.
• a coating technique e.g., by spraying, whirling, dip-coating, 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, exposure, recording and/or transfer technique wherein the recording material is used.
• support has an electric volume resistivity lower than that of the recording layer, preferably at least 10 as low as that of the photoconductive recording layer.
• Suitable supports are described, e.g., in the United Kingdom Pat. No. 995,491 filed Mar. 16, 1962, No. 1,020,503 filed Nov. 8, 1961 and No. 1,020,504 filed Dec. 29, 1961 all by Gevaert Photo-Producten N.V. and in the U.S. Pat. No. 3,008,825 of Warren G. Van Born and Osmar A. Ulbrich Jr., issued Nov. 14, 1961.
• Preferably used supports are conductive paper supports, more preferably glassine type paper supports.
• the photoconductive layer of an electrophotographic material which is prepared by starting from a coating composition according to the present invention, can be used for recording purposes, in which prior to exposure an electric charge is nondifferentially applied according to known methods.
• the material can also be used in recording techniques, in which the exposure step precedes the charging step.
• recording techniques in which the exposure step precedes the charging step.
• the charging as already explained can be effected with a negative as well as with a positive corona.
• a corona charging system suited for a rapid change from negative to positive corona charging operates with a so-called floating earth having corona wires of opposite charge sign under and in front of the recording layer to be charged.
• Well-established methods of developing electrostatic images include cascade-, powder cloud-, magnetic brushand fur brush-development. These methods are based on the application of charged dry toner to the surface bearing the electrostatic image. Other methods are based on the use of liquids, either insulating (electrophoretic development which is preferred) or conductive liquids (see, e.g., the U.S. Pat. No. 2,907,674 of Kenneth A. Metcalfe and Robert J. Wright, issued Oct. 6, 1959 and the Belgian Pat. No. 610,060 filed Nov. 8, 1961 and No. 625,335 filed Nov. 27; 1962 both by Gevaert Photo-Producten N .V.). Development of a conductivity image based on electrolysis is described, e.g., by J. A. Amick, RCA Rev., 20, 753 (1959).
• EXAMPLE 1 2,309 g. of a 20 percent solution in dichloroethane of HYPALON 30 (registered trademark for a copoly(ethylene/vinylsulphonyl chloride/vinyl chloride) (26.1/6.9/67 percent by weight) marketed by E. I. du Pont de Nemours & Co. (Inc.) Wilmington, Del.,) where diluted ,with 535 ml. of dichloroethane, 560 ml. of methyl ethyl ketone and 112 ml. of ethanol. While stirring 1,820 g. of photoconductive zinc oxide (marketed by Vieille Montagne S.A.
• the coating composition containing urazole and a same coating composition without urazole were applied in the same conditions to a glassine paper support and conditioned after drying at 20 C. and 50 percent of relative humidity.
• EXAMPLE 3 One hundred and one grams of HYPALON 30 (registered trademark) were dissolved in a mixture of 575 ml. of dichloroethane, 156 ml. of methyl ethyl ketone, and 31 ml. of ethanol.
• As dispersing agent for the photoconductive pigments 19.5 ml. of a 80 percent solution in toluene of CEL- LOLYN 95 (an acid alkyd resin marketed by The Hercules Powder Company Inc., Wilmington, Del., were added to this solution. Thereupon 447 g. of photoconductive zinc oxide (Type A Neige extra pur-Vieille Montague S.A., Belgium) and 61 g.
• CADMOPUR GOLDGELB N (trade name of Kontigriken Bayer AG LeverkusenW. Germany, for a cadmium sulphide pigment containing 76 percent of cadmium. 22 percent of sulphur, 2 percent of a mixture of barium sulphate and silica, and traces of zinc and selenium were admixed while stirring.
• To the pigment dispersion 4 ml. ofa 10 percent solution of urazole in dimethylformamide were added and intimately mixed therewith. The pigment composition was then put once through a sand-mill (Sandmill-Sussmeyer, Type IA) at a rate of24 liters/h).
• the dispersion was coated onto glassine paper at a rate of 33 g. of solids per sq.m.
• the coating was dried in a laminar current drier at 30-40 C. (air rate 7 m./min). A smooth surface was obtained.
• the dried material was charged with a double corona, the corona wires in front of the recording layer and those below the support having a potential difference of 5000 v. and +5000 v. respectively in respect of the ground.
• a step wedge with constant of 0.1 was projected on the recording layer by means of a set of incandescent lamps.
• the exposed material was electrophoretically developed with a hydrocarbon solvent-carbon dispersion.
• the developed image proved that the recording layer was suited for the production of images with a steep gradation so that text originals were reproduced with a very sharp letter on a clear background.
• the images showed a high density and the recording material proved to have a small memory effect and a high sensitivity to light.
• EXAMPLE 4 Six hundred and eighty-four milliliters of a 57.5 percent by weight solution in toluene of copoly(vinyl acetate/methyl acrylate/acrylic acid) (87/ 12/ 1 percent by weight) were diluted with 3,316 mi. of toluene. While stirring the following ingredients were added:
• French type hotoconductive zinc oxide (average particle size 0.5 p.) 2.400 kg. [0% by weight solution of urazole in dimethylformamide l9.2 ml. 1% by weight solution of bromophenol blue in methanol l8 ml.
• the dried material was negatively corona-charged till 500 v. with a double corona, the corona wires in front of the recording layer and below the support having a potential difference of 5000 v. and +5000 v. respectively in respect of the so-called floating earth.
• the charged recording layer was projection-exposed for 3 see. by means of an incandescent tungsten filament lamp of watt/12v. placed at a distance of 30 cm., through a linework transparency (diapositive) and developed in an electrophoretic developer on the basis of positive toner particles.
• the developer was produced by diluting the concentrated developer composition described hereinafter in a volume ratio of 15/1000 by means of lSOPAR H (trade name for an isoparaffinic hydrocarbon mixture having a boiling range of l77-l88 C., sold by Esso Belgium N.V., Antwerp, Belgium):
• the resin binder solution was prepared by heating 500 g. of ;E Q.-
• ALKYDAL L 67 (trade name of Wegriken Bayer A.G.,' l Leverkusen, W. German, for a linseed oil-modified (67 percent by weight) alkyd resin and 500 ml. of white spirit contain- EXAMPLE 7 ing 1 1 percent by weight of aromatic compounds at 60 C. tillf EFEFfiEQFBIlQFYi l l qll'iqi l q lfilipiii fll E'L BE;
• Example 5 was repeated, except that the urazole was replaced by a same amount of the compound having the fol- The same recording layer was positively corona-charged till 1 lowing formula:
• the obtained dispersion was applied by knife coating to a conductive paper base of 67 g./sq.m at a rate of 25 g. of solids 1 per sq.m.
• the obtained layer was dried at 80f bromophenol blue in methanol l2 ml. 3 0.5% by weight solution or The obtained mixture was homogenized, filtered and oin d
• the dried recording layer was negatively corona-charged at a rate of 27 g. of solids per sq.m onto a glassine paper contill -600 v. with a double corona, the corona wires in front of taining conductivity-increasing salts.
• the coated layer was dried in a laminar current drier at 60 P n i l difference -i and +1 respecllve y respect of the ground. 7
• the positively charged recording layer was exposed in the same optical enlarger as described above but to a negative microfilm image as an original.
• Example 8 was repeated, except that the urazole, was
• each of R,, R and R represents hydrogen, an alkyl group, acyl group, an aryl group, or a at least one of R R or R being hydrogen.
• binding agent is a vinyl copolymer containing hydrophobic structural units and acidic structural units derived from afl-ethylenically unsaturated carboxylic acid compounds.
• a method for recording and reproducing information according to claim 2, wherein the groups from which an acid can be produced in situ are carboxylic anhydride groups or sulphonyl chloride groups.
• a method for recording and reproducing information comprising the step of forming an information wise electrostatic charge pattern by electrostatically charging and information-wise exposing to active electromagnetic radiation an electrophotographic recording material containing a photoconductive recording layer comprising photoconductive zinc oxide treated with a compound corresponding to the following general formula (including its salt and tautomeric structures):
• each of R,, R and R represents hydrogen, an alkyl group, acyl group, an aryl group, or a pyridine nucleus, or a thiazole nucleus at least one of R,, R R being hydrogen.
• a metho d for recording and reproducing information as:
• each of R R and R represents hydrogen an alkyl group, acyl group, an aryl group, or a pyridine nucleus, or a thiazole nucleus at least one of R,, R or R being hydrogen.
• a recording material accordingto claim 16 wherein the said compound is added to the composition of the layer containing the zinc oxide in an amount of 0.01 to 10 percent by weight in respect of the photoconductive zinc oxide.
• a recording material according to claim 4 wherein in the photoconductive zinc oxide as been dispersed in a binder medium containing at last one binding agent comprising acidic groups or groups from which an acid can be produced in situ.
• each of R,, R and R represents hydrogen, an alkyl group acyl group, an aryl group, or a pyridine nucleus, or a thiazole nucleus at least one of R R or R, being hydrogen.

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• Photoreceptors In Electrophotography (AREA)

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Citations (4)

• 1968
  • 1968-06-06 GB GB2704568A patent/GB1256888A/en not_active Expired
• 1969
  • 1969-06-03 CA CA053360A patent/CA933016A/en not_active Expired
  • 1969-06-05 CH CH857069A patent/CH548054A/xx not_active IP Right Cessation
  • 1969-06-06 US US831253A patent/US3634080A/en not_active Expired - Lifetime
  • 1969-06-06 NL NL6908638.A patent/NL158943B/nl not_active IP Right Cessation
  • 1969-06-06 BE BE734139D patent/BE734139A/xx not_active IP Right Cessation
  • 1969-06-06 FR FR696918897A patent/FR2010309B1/fr not_active Expired
• 1971
  • 1971-07-21 US US164821A patent/US3692522A/en not_active Expired - Lifetime

Patent Citations (4)

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