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
  • G03G5/0644—Heterocyclic compounds containing two or more hetero rings
  • G03G5/0661—Heterocyclic compounds containing two or more hetero rings in different ring systems, each system containing at least one hetero ring
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09B—ORGANIC DYES OR CLOSELY-RELATED COMPOUNDS FOR PRODUCING DYES, e.g. PIGMENTS; MORDANTS; LAKES
  • C09B23/00—Methine or polymethine dyes, e.g. cyanine dyes
  • C09B23/0075—Methine or polymethine dyes, e.g. cyanine dyes the polymethine chain being part of an heterocyclic ring
• • 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
  • G03G5/06—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
  • G03G5/0672—Dyes containing a methine or polymethine group containing two or more methine or polymethine groups
  • G03G5/0674—Dyes containing a methine or polymethine group containing two or more methine or polymethine groups containing hetero rings

Definitions

• the present invention relates in general to optically sensitized photoconductive layers comprising zinc oxide and in particular to the provision of novel sensitizing dyestuffs for such purposes.
• Electrostatic printing processes for the production of visible records or reproduction are well known in the art being extensively described in the literature both patent and otherwise. In general, such processes encompass as the salient features of operation the conversion of a light-image or electrical signal into an electrostatic charge pattern on an electrically insulating layer. Image-forming development can thereafter be effected according to any one of several procedures whereby to render the latent charge pattern visible.
• Electrophotographic processes based upon the utilization of photoconductive layers include of course the xerographic methods in which an electrically conductive support is first subjected to a uniform electrostatic charge in the dark this being accomplished for example by means of a high voltage corona discharge whereby an electrostatic charge is created on the element surface.
• Latent image formation can thereafter be effected by focussing a light-image on the charged surface, the light energy serving to selectively dissipate the electric charge in proportion to the intensity of the incident light radiation, i.e., an imagewise dissipation of the electric charge in accordance with the impressed lightimage.
• the residual charged areas of the photoconductive layers i.e., those protected by the image areas of the original and thus unaffected by the exposure radiation provide what is tantamount to a latent electrostatic image pattern which can be readily rendered visible by application thereto of a suitable colorant, e.g., toner powder, having optical density sufficient to permit visible discernment of the image areas and which readily adheres to the residual charged areas.
• photoconductive layer for use in electrophotographic reproduction processes of the foregoing type are conventionally prepared with such photoconductor materials as selenium, cadmium sulfide, zinc oxide, etc. For a plurality of reasons, zinc oxide has proved to be particularly beneficial for the vast majority of operations associated with electrography.
• the zinc oxide photoconductor material is conventionally employed in photoconductive layers in the manner described, i.e., a grounded support usually paper, is initially rendered sensitive to light by subjecting same to a blanket negative electrostatic charge on the zinc oxide layer in the substantial absence of any ultraviolet or visible radiation.
• this step can readily be effected by means of ion transfer from a corona discharge.
• the resulting latent image areas, i.e., nonlight-struck portions of the photoconductive layer are developed, for example, with a pigmented resin powder having a charge opposite to the negative charge of the unexposed areas of the photoconductive layer. In this fashion, the pigmented powder firmly attaches itself via electrical attraction to such negatively charged areas.
• the strength of adhesion of the resin powder to the image bearing layer can be enhanced by a suitable fixing operation as for example by simply heating the resinous material to temperatures sufficient to fuse or melt same whereby such resin becomes permanently affixed to the surface of the image layer. It is to be understood of course that the temperatures employed in this operation should be selected so as to avoid any possibility of charring the paper support. In any event, suitable methods for effecting the development of a latent electrostatic image pattern are described in the prior art with recourse to a particular one depending primarily upon the requirements of the processor.
• Photoconductor substances which have heretofore been suggested for such purposes include, for example, the colored oxides, sulfides, selenides, tellurides, and iodides of such materials as cadmium, mercury, antimony, bismuth, thallium, molybdenuln, aluminum, lead, zinc, etc.
• the industrial effort thus far expended has been concerned with the development of materials capable of absorbing radiant energy and of transferring the energy so absorbed to the photoconductor.
• sensitizing dyes with the zinc oxide photoconductor for the purposes of imparting the requisite spectral sensitivity to the reproduction system.
• Representative dyestuff materials heretofore promulgated in this regard include, for example, rose bengal, eosin, malachite green, crystal violet, methylene blue, methylene grey, fluorescein and the like.
• the primary objection to the sensitizing dyestuffs thus far suggested relates to their pronounced tendency to impart to the sensitizing formulation a spurious off-white tint or coloration thus vitiating to a significant extent attempts to achieve satisfactory contrast, gamma and the like. More specifically, such dyestuffs lead to the formation of tints which may be blue, green, yellow, orange or red as well as various shades and hues thereof. Moreover, as will be appreciated, the undesired coloration of the zinc oxide layer is objectionable from an aesthetic standpoint the latter being a relatively important consideration bearing directly upon the possibilities of commercial acceptance. In some instances, the recording element itself may be contemplated for further exposure sequence, e.g., the production of either black and white or color prints therefrom.
• discoloration of the coated element results from the inter-layer diffusion of acidic or alkaline materials, as the case may be, such conditions being conducive to the creation of spurious, off-white tints.
• fugitive coloration of the electrophotographic element is not only aesthetically displeasing but, and perhaps more importantly, renders such element substantially unsuitable for further photocopying operations.
• a primary object of the present invention relates to the provision of novel dyestuff materials advantageously adapted for use with electrographic layer compositions and wherein the foregoing and related disadvantages are eliminated or at least mitigated to a substantial extent.
• a further object of the present invention relates to the provision of optically sensitized electrophotographic layer compositions having excellent sensitometric properties, e.g., speed, contrast, gamma, ets., said compositions being capable of yielding high qaulity reproduction.
• Another object of the present invention relates to the provision of optically sensitized electrophotographic layers having excellent actinic response and stability characteristics, said layers being substantially devoid of any tendency to develop spurious coloration.
• R, R and R independently represent alkyl, e.gl, carboxy group in free acid form connected to the dyestufi' methyl, ethyl, propyl, butyl, isobutyl, etc.; aralkyl, e.g., molecule by an alkylene bridge; thus, such term includes benzyl, fi-phenethyl; hydroxyalkyl, e.g., hydroxethyl; carboxymethyl, carboxyethyl, carboxy-n-propyl, etc.
• alkoxyalkyl e.g., B-ethoxyethyl
• carbalkoxyalkyl e.g., improvements provided by the present invention have been carbomethoxymethyl, carboethoxymethyl, carboethoxyascertained to obtain to an optimum extent when such ethyl
• acyloxyalkyl e.g., [3acetoxyethyl, and the like, with group comprises either carboxymethyl or carboxyethyl.
• R, R and R represents As particular examples of dyestufi materials falling carboxyalkyl, e.g., carboxymethyl, carboxyethyl, etc.; R within the ambit of the above structural formula and and R represent hydrogen, alkyl, e.g., methyl, ethyl, etc.; found to provide exceptional advantage as sensitizing aryl, e.g., phenyl; aralkyl, e.g., benzyl, phenethyl, etc.; agents with photoconductive layers contemplated for use hydroxyalkyl, e.g., B-hydroxyethyl, etc.; m, n, p and q in electrophotography, there may be mentioned the foleach represents a positive integer of from 1 to 3 inclusive; lowing: X represents an acid anion, e.g., chloride, bromide, thiocyanate alkyl sulfate, such as, methylsulf
• the aforemen- $222111:'ethylbenzoxazolyhdene)ethyhdeneM'om tioned heterocyclic nucleic may further contain one or Thrazolmium, 2-(3-carboxymethyI-Z-benzothiazolylidenemore groups which comprise conventlonal substrtuents with respect to dyestuffs of this general type.
• the photoconductive layer compositions of the present invention may be prepared according to conventional procedures described in the prior art, i.e. utilizing conventional solvents, coating aids, driers, etc., such ingredients being of an optional nature.
• the essential components of the photoconductive composition comprise the sensitizing dye, the photoconductor material, i.e., zinc oxide, the latter being dispersed in an insulating binder material having relatively high dielectric strength and good electrical insulating properties.
• film-forming insulating binders found to be suitable for use herein there may be mentioned the following: styrene-butadiene copolymers; silicone resins; soya-alkyd resins; poly(viny1 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(methyl methacrylate), poly(n-butylmethacrylate), poly(isobutyl methacrylate), etc.; polystyrene; nitrated polystyrene; polymethylstyrene; isobutylene polymers; polyesters, such as poly(ethylenealkaryloxyalkylene terephthalate); phenol-formaldehyde resins; ketone resin
• styrene alkyd resins can be prepared according to the method described in US. Patents 2,361,019 and 2,258,423.
• Suitable resins of the type contemplated for use in the photoconductive layers of this invention are sold under such trade names as Vitel PE-lX, Cymac, Piccopale 100, and Saran F-220.
• Other types of binders which can be used in the photoconductive layers of the invention include such materials as paraffin, mineral waxes, etc.
• polymeric materials found to be especially advantageous include, for example, a polyester material available commercially from the Celanese Corporation of America under the commercial trade name designation Epitex 1311, which is prepared by reacting epichlorohydrin with bisphenol A employing the former in slight molar excess and thereafter reacting the polyether obtained with a mixture of a dimerized fatty acid and soya fatty acid.
• the resultant product comprises a linear, acetone-soluble, nonheat curable polymer material containing epoxy groups. Methods for the preparation of such polymers are described, for example, in U.S.P. 2,970,983.
• a further material found to be admirably suited for use herein comprises a product available commercially from the Pennsylvania Industrial Chemical Company under the trade name designation Piccolastic which is identified as being a low molecular weight (on the order of approximately 400), low melting point (approximately 75 C.) polystyrene resin.
• Piccolastic which is identified as being a low molecular weight (on the order of approximately 400), low melting point (approximately 75 C.) polystyrene resin.
• resinous binder as used herein is thus to be accorded a significance consonant therewith, i.e., extending to either the singular or conjuctive use of such resin materials.
• Suitable solvents for effecting homogeneous dispersion of the ingredients comprising the layer composition include, for example, toluene, Xylene, benzene, acetone, 2-butanone, chlorinated hydrocarbon, e.g., methylene chloride, ethylene chloride, etc. ethers, e.g., tetrahydrofuran or mixtures of such solvent materials.
• the ingredients comprising the photoconductive coating composition may be provided in the form of an aqueous system in contradistinction to an organic solvent system. Improved sensitization results with either method. Again, recourse to either a solvent or aqueous system will be dictated in large part by the requirements of the processor.
• photoconductive coating composition to the support material can be effected according to standardized methods, well known in the prior art.
• coating methods such as doctor-blade, swirling, dip-coating and the like may be employed.
• the thickness to which the photoconductive layer composition is deposited may vary over a relatively wide range; in general, however, wet coating thicknesses Within the range from about .001" to about 0.01" are found to be eminently suitable for accomplishing the purposes of the present invention. Particularly beneficial results are found to obtain with the use of wet-coating thicknesses falling within the range from about .002" to about .006".
• the support material employed may be any of the conventional materials promulgated in the art for the fabrication of electrostatic recording elements the principal requirement being that such materials exhibit adequate electrical conductivity.
• Such materials include, for example, paper (at a relative humidity above about 20%); aluminum-paper laminates; metal foils, such as, aluminum foil, zinc foil, etc., metal plates, such as, aluminum, copper, zinc, brass, and galvanized plates; regenerated cellulose and cellulose derivatives; certain organic polymeric plastic materials, e.g., polyester and especially polyesters provided with a thin electroconductive layer, such as cuprous iodide coated thereon.
• Suitable supporting materials include in addition the humidity-independent conducting layers of semi-conductors dispersed in polymeric binders.
• ingredients which may be incorporated into the coating composition for purposes of expediting the coating operation as well as to render the ultimate coating more suitable for use in the image recording process include, for example, plasticizers; e.g., polymeric hydrocarbons having a fair degree of aromaticity and low iodine value; drying agents, e.g., cobalt naphthenate, manganese naphthenate and the like.
• the zinc oxide photoconductor materials contemplated for use herein are available commercially. Desirably, the zinc oxide should be provided in the form of relatively small particles having a mean diameter of less than about 0.5 micron. Particularly preferred for use herein is the zinc oxide product produced according to the French Process such as French Process, Florence Green Seal, pigment grade zinc oxide commercially available from the New Jersey Zinc Sales Company Inc. of New York. Other zinc oxide materials preferred for use herein include, for example, the product commercially known as St. Joe PC321 zinc oxide. Optimum realization of the advantages provided by the present invention is obtained by employing the insulating binder in amounts sufficient to insulate each of the zinc oxide particles from the remaining ingredients of the coating composition. Such proportions can be readily determined by rather route laboratory investigation.
• the recording elements described herein can be advantageously employed with any of the well known electrophotographic processes based upon the use of photoconductive layers, e.g., the Xerographic process the latter being carried out by initially subjecting the electrophotographic element to a blanket electrostatic charge, e.g., by the use of a corona discharge.
• the uniform charge extent over the surface of the photoconductive layer is retained, such layer also having the property of negligible conductivity in the dark or, as more commonly stated, high dark resistivity.
• Exposure of the photoconductive layer to light erves to effect an imagewise dissipation of the electrostatic charge from the surface of the layer thus leading to the formation of a latent electrostatic charge pattern may be effected through a negative by conventional exposure methods as for example, by contact printing techniques or alternatively by lens projection of an image.
• the extent of pointto-point charge dissipation depends correspondingly upon point-to-point intensity of the exposure illuminant.
• the residual charge pattern is thereafter rendered visible or otherwise developed by treatmnt with a suitable colorant, pigment, etc. comprising electrostatic particles having a charge opposite to that of the residual charge constituting the electrostatic latent image pattern, said developing agent being capable of ready visual comprehension.
• the developer agent may comprise, for example, a liquid developer in which the developing particles are suspended in an electrically insulating liquid carrier.
• Developing methods of this type are of course well known being described, for example, in U.S.P. 2,296,691 and in Australian Patent 212,315.
• Other developing methods depending upon, for example, heat fusion of resin particles, image transfer are likewise well known in the art and may be utilized to advantage in the practice of the present invention.
• EXAMPLE I An electrophotoconductive coating composition is prepared in the following manner:
• Epitex 1311 a polyester obtained by reacting epichlorohydrin with bisphenol A to form a polyether and thereafter reacting the latter with a mixture of dimerized fatty acid and soya fatty acid as described in U.S.P. 2,970,983).
• 454 gm. of zinc oxide photoconductor (St. Joe P0321) is added to the solution while stiirring.
• a resin solution containing 35 gm. of piccolastic A75 polystyrene resin having a molecular weight of approximately 400 and a melting point of approximately 75 C.
• the medium is thereafter stirred and milled until smooth. At this point there is added 20 mg. of the sensitizing dyestuff,
• a coated paper is thereafter evaluated electrophotographically by exposure in a Bruning Copytron 2000 the latter comprising commercially available eletcrophotographic copying apparatus based upon dry toner development.
• the prints obtained are characterized by excellent density, contrast, etc. and are totally devoid of spurious coloration thus providing high contrast copy.
• the dyestutf employed in the above example is prepared in the following manner:
• N CH2 l COOH is added with 5 parts of methanol and 30 drops of triethylamine.
• the solution is then heated on a steam bath and glacial acetic acid is added, whereupon the initial stages of dye formation is detected. Thereupon, toluene is added as well as potassium iodide in acetone.
• the solution is then transferred to a centrifuge tube, centrifuged, decanted and the residue boiled out with toluene, recentrifuged (hot) and again decanted. The residue is boiled out with methanol, cooled and filtered to yield 0.2 part of dyestutf which, upon analysis, was determined to be:
• Compound A above is prepared by reacting 3-carboxymethyl rhodanine, in the presence of methanol and triethylamine with the following compound:
• the sensitizing dyestuffs of the present invention may be employed to advantage either singly or in admixture. Moreover, they may be used in combination with one or more of the dyestufl sensitizing materials heretofore described in the art. In any event, it is recommended practice to maintain the proportions of the instant dyestufi products within the concentration range hereinbefore specified in order to assure the obtention of optimum results. It is envisaged that in some instances sensitizer dyestuff concentration may be considered desirable which are substantially in excess of the delineated range. For example, it may be that the speed requirements of the process may dictate such a departure.
• R, R and R independently represent a member selected from the group consisting of alkyl, aralkyl, hydroxyalkyl, alkoxyalkyl, carbalkoxyalkyl, acyloxyalkyl with the provision that at least one of R, R and R represent ca'boxyalkyl;
• R and R represent a member selected from the group consisting of hydrogen, alkyl, aryl, aralkyl, hydroxyalkyl, m, n, p and q each represents a positive integer of from 1 to 3 inclusive,
• Y and Y" each represents the atoms necessary to complete a 5 or 6-membered heterocycle, Y represents a member selected from the group consisting of oxygen, sulfur, selenium and nitrogen, and
• X represents an acid anion.
• sensitizing dyestufi comprises thiazolinium, B-carboxymethyl-Z-(3-carboxyethyl-5-methoxy 2-benzoselenazoly1- idene-methyl)5-[2-(3-benzyl 2 benzoxazolidene)ethylidene]-oxo iodide.
• sensitizing dyestuff comprises thiazolinium, 3-carboxyethyl-2-(3-carboxyethyl 5 chloro 2-benzothiazo1ylidene-rnethyl(5-[2-(5,6-dimethyl 3-ethyl-2-benzoxazolylidene)ethylidene]4-oxo bromide.
• sensitizing dyestuif comprises thiazolinium, 2-(3-carboxyethylbenzoselenazolylidene-methyl)5 [2 (Ii-carboethoxymethyl-4-methylthiazo1y1idene)ethylidene]4 oxo iodide.
• sensitizing dyestulf comprises thiazolinium, S-carboxymethyl-2-(3-carboxymethyl 5 chloro-Z-benzothiazolyl- 14 idene-methyl)5-[2 ,5,'6-dimethy1 3 ethylbenzoxazolylidene)ethylidene]4-oxo bromide.
• sensitizing dyestuff comprises thiazolinium, 2-(3-carboxymethyl-2 benzothiazolylidenemethyl) 3 thyl-S-(3- methylbenzothiazolylidene) 4-oxo iodide.
• sensitizing dyestufl? comprises thiazolinium, 2-(3-carboxymethyl-2-benzothiazolylidenemethyl)3 ethyl 5-(2-[3- ethyl-2-benzothiazolylidene]ethylidene)4-oxo iodide.
• sensitizing dyestuff comprises thiazolinium, 3-carboxyethyl-2-(4,5-diphenyl 3 ethyl-2-oxazolylidenemethyl) 5-(3-methylthiazolinylidene)4-oxo iodide.
• sensitizing dyestuif comprises thiazolinium, 3-carboxymethyl-2-(3-ethyl 5 methyl-4-phenyl-2-thiazolylidenemethyl) 5-(3-methylthiazolinylidene) 4-oXo iodide.
• An electrophotographic recording element comprising a backing member overcoated with the composition of claim 1.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Photoreceptors In Electrophotography (AREA)
• Plural Heterocyclic Compounds (AREA)
• Heterocyclic Carbon Compounds Containing A Hetero Ring Having Nitrogen And Oxygen As The Only Ring Hetero Atoms (AREA)

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Citations (4)

• 1967
  • 1967-01-31 US US612781A patent/US3507649A/en not_active Expired - Lifetime
• 1968
  • 1968-01-22 FR FR1558595D patent/FR1558595A/fr not_active Expired
  • 1968-01-23 DE DE1695112A patent/DE1695112C3/de not_active Expired
  • 1968-01-23 CH CH101468A patent/CH506816A/de not_active IP Right Cessation
  • 1968-01-23 GB GB3575/68A patent/GB1213354A/en not_active Expired
  • 1968-01-26 BR BR196548/68A patent/BR6896548D0/pt unknown
  • 1968-01-30 SE SE01224/68A patent/SE330484B/xx unknown
  • 1968-01-30 BE BE710079D patent/BE710079A/xx unknown
  • 1968-01-31 NL NL6801403A patent/NL6801403A/xx not_active Application Discontinuation

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