US3165458A - Electrolytic recording sheets - Google Patents

Electrolytic recording sheets Download PDF

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Publication number
US3165458A
US3165458A US140032A US14003261A US3165458A US 3165458 A US3165458 A US 3165458A US 140032 A US140032 A US 140032A US 14003261 A US14003261 A US 14003261A US 3165458 A US3165458 A US 3165458A
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US
United States
Prior art keywords
silica
photoconductive
coating
layer
copysheet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US140032A
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English (en)
Inventor
Benjamin R Harriman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
3M Co
Original Assignee
Minnesota Mining and Manufacturing Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE622712D priority Critical patent/BE622712A/xx
Priority to NL283382D priority patent/NL283382A/xx
Application filed by Minnesota Mining and Manufacturing Co filed Critical Minnesota Mining and Manufacturing Co
Priority to US140032A priority patent/US3165458A/en
Priority to DE19621497009 priority patent/DE1497009B2/de
Priority to CH1099462A priority patent/CH418133A/de
Priority to GB35889/62A priority patent/GB1021885A/en
Priority to DK412162AA priority patent/DK104551C/da
Priority to FR910054A priority patent/FR1499851A/fr
Priority to ES0280188A priority patent/ES280188A1/es
Application granted granted Critical
Publication of US3165458A publication Critical patent/US3165458A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G17/00—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process
    • G03G17/02—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process with electrolytic development
    • 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
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • 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
    • G03G5/14—Inert intermediate or cover layers for charge-receiving layers
    • G03G5/147—Cover layers
    • G03G5/14704—Cover layers comprising inorganic material
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G9/00—Developers
    • G03G9/06—Developers the developer being electrolytic

Definitions

  • This invention relates to new and useful sheets for the reproduction of visible images.
  • this invention relates to improved image recording sheets which can be developed by electrolytic techniques.
  • this invention relates to a method-for the preparation of such sheets and to a method yfor their use in image reproduction.
  • Photoconductive coatings and sheet constructions have been suggested for a variety of purposes, including the reproduction of light images.
  • a recently developed image reproduction process involves electrolytically developing permanent and visible images on suitable photoconductive copysheets after exposure to actinic light images.
  • This method described more fully in United States patent application, Serial Number 575,070, filed March 30, 1955, now US. 3,010,883, includes the electrolysis of an electrolytic developer and particularly the electrodeposition of a metallic or other visibly distinct coating at the exposed photosensitive surface, usually by electrolytic reduction. No preliminary charging of the copysheet is required, and the copy produced needs no further heating or other processing to render the image permanent.
  • Another object of this invention is to provide a photoconductive copysheet which can be electrolytically developed to produce a visible image having improved image density, greater image contrast and better smudge resistance.
  • Still another object of this invention is to provide an improved photoconductive copysheet which is resistant to pinpointing and to yellowing.
  • a further object of this invention is to provide a photoconductive copysheet of improved appearance.
  • Yet another object of this invention is to provide a process for preparing an improved photoconductive copysheet.
  • Another object of this invention is to provide a means for preparing photoconductive copysheets having different degrees of gloss.
  • An improved photoconductive copysheet of this invention comprises a continuous electrically conductive layer having thereon a thin, continuous and contiguous layer of photoconductive particles in a Water-insoluble, insulative binder and, superimposed thereon, though not necessarily in direct contact therewith, a thin, continuous, glossy, adherent, transparent, cohesive, water permeable and water insoluble layer comprising a film forming silica.
  • the silica must have film forming properties, as distinct from the silicas which dry from the aqueous sol to noncohesive, readily disruptable powder.
  • the former siiicas are capable of forming a stable colloidal sol with a particle size in the 1 to 100 millimicron diameter range, preferably from about 10 to about 50 millimicrons.
  • silicas which are capable of producing the desired glossy, adherent, cohesive, water permeable layer are available as aqueous colloidal sols with up to about 50% solids in the above particle size range, which sols are of high purity and are substantially free of alkali metal cations, eg. sodium, potassium, etc. They may be prepared by the progressive growth in aqueous sodium silicate solution of silica particles, such silica forming on nuclei of silicio acid. The alkaline sol thereby produced is deionized to remove sodium ion and reduce the pH to below 5, preferably below 4, by passage through an ion exchange bed. Such procedure is described in United States Patent No. 2,244,325.
  • An illustrative silica sol is Nalcoag 1034A, a deionized acid sol containing 34% solids by weight and a particle size range of 16 to 22 millimicrons (available from Naco Chemical Company, Chicago, Illinois).
  • Other Nalcoag siiica sols such as those identified as 1015, 1022, 1030, 1035 and 1050, are suitable after deionization.
  • Silica sols sold by E. I. du Pont de Nemours and Co., Wilmington, Delaware, under the trade name Ludox may also be used after deion-ization.
  • Chemically modiiied silicas, eg. esterified silicas, having the above properties may also be used.
  • the pyrolytically produced silicas though readily dispersible in water, are generally incapable of forming the desired glossy and continuous, cohesive film on the photoconductive copysheet surface. Additional ion exchange treatments of available film forming silica sols may be desired to remove traces of undesirable alkali metal cations, such as sodium ion, and hence to reduce the tendency of the top-coated photoconductive copysheet to pinpoint during electrolytic development. Por example, less than parts per million of sodium ion (calculated as NaOH) is preferred.
  • the various silica sols may be readily evaluated for suitability as film-forming silica sols and for other of the aforementioned properties by dip coating a ground, non-corrosive microscope slide into the silica sol, and removing and drying either with a hot air current or at ambient room conditions.
  • the surfaces of the slide should be previously ground with a fine abrasive, i.e. a grit size in the 320 to 500 mesh range,
  • the useful silica sols willdry Without blushing to a water insoluble film that reduces theY dispersivity and increases the transparency ofthe 'ground glassfsurface.
  • Aqueous solutions of dyes such as methylene blue will .be strongly adsorbed on the coated surface and are not substantially removed by krinsing in Water.
  • the sol is diluted with water to reduce the coating thickness and the test is repeated.
  • other silica sols of a non-film forming nature evidence blushing upon drying andwill not dry to a coating having any significant transparency.
  • the non-film forming silica coatings are primarily particulate and can be rubbed off the surface ⁇ readily. Little or no dye, eg. methylene blue, will adhere to the coated area upon rinsing the dyed slide in water.
  • organic film formers such as polyvinyl alcohol, polyvinyl pyrrolidone, dimethyl hydrantoin formaldehyde, gelatin, etc. ⁇ have proven unsatisfactory and tend to produce such harmful effects as a significantly lower development rate, pin- ⁇ pointing, formation of gas bubbles under the topcoating 'during development, and serious residual developer stain or discoloration.
  • the glossy silica topcoatings may be prepared by dip, knife, bar, brush or roller coating of the photoconductive copysheet surface with an aqueous sol of the film forming silica, or, if desired, by such techniques as doctoring, gravure offset, etc. to insure uniform coating thickness.
  • Other coating techniques including those errployed in the photographic art, may also be used.
  • any coating method used for coating a uniform ylayer of low viscosity material upon a non-absorbent substrate can be utilized.
  • Surfactants either cationic or nonionic, may be included in the aqueous silica sol to cnhance wetting characteristics and improve the uniformity of the resultant coating.
  • surfactants When used, such surfactants are employed at low concentration to avoid fogging the photoconductive coating.
  • surfactant concentrations are preferably below 0.06% based on silica Weight.
  • Wetting eharcteristics may also be enhanced by including a wateramiscible organic solvent, up to'about 20% by volume, in the aqueous sol.
  • Lower alkyl alcohols, Vsuch as isopropanol and methol, are particularly desirable for this purpose.
  • the volatility of the water miscible organic solvent should be close to that of water to prevent orange pee caused by non-uniform solvent lloss during the drying of the silica topcoating.
  • Coating thickness is important in obtaining the improvements discussed herein. Although ythe coating effect the desired continuous film and gloss characteristics and t-he maximum rate at which crazing'of the film observable by the naked eye is produced, coating Weight of thek silicaon the photoconductiveV copysheet surface can be adjusted to obtain the desired balance of properties, such as maximum glosswith good Water permeability and fast-electrolytic development rate. From about 0.1 to aboutv 10, preferably from l to 6, grams of silica Yper square meter has proven satisfactory in most cases. With coating weights above about l grams of silica per square meter the electrolytic development rate becomes relatively slow.Y For lower gloss papers, the lower coating weights areernployed.
  • the transparent cohesive silica films of this linvention may also include various other additives, including the developer materials themselves (eg. zinc, silver and other metal salts, electrolytically reducible dyes), and a wide variety of other materials such as filter dyes, AlGOH, ammonium 'persulfate, ceric sulfate, HC1, HNO3, H3PO4, ZnCl2, ZnF2, Zn(NO3)2, Mg(NO3)2, acetamide, MgSCh urea,V acrylamide, quinone, acetic acid, thiourea, NN- methylene bis-acrylamide, ethylene diamine teu-acetic acid, ascorbic; acid, hydroquinone, phenols, morpholine, sucrose, carbowax, etc.V Up to about Weight percent,
  • the dry coating weight must be thick enough to provide a continuous glossy topcoating but thin enough to avoid any noticeable .excessive crazing or minute lcrack formation in the silica topeoating. Grazing is aggravated by uneven or excessively ra id drying of the wet silica coating, e.g. by elevated temperature drying, as is known in paint technology. Air drying at in an amount insufficient to adversely affect the gloss characteristics of the dry coating, usually up to about 25% by Weight of the silica. Withinrthe silica coating Weight range encompassed bythe minimum Weight to they may also be coated onto intermediate layers or materials which are themselves in contact with thel photoconductive surface.
  • various"photoconductive copysheets having a thin, light .transmissive indium oxide developer coating on the photoconductive layer may be overcoated with the glossy silica layers of this invention.
  • various'otherphotoconductive copysheets are provided with avgelatin coating containing the desired developer materials, as exemplified in United States Serial Number 575,070,.now U.S. 3,0l0,883, and these .may also be overcoated with the glossy silica layers of this invention.
  • the term superimposed on includes bothdirect and indirect Contact Withthe underlying photoconductive layer.
  • a stabilization step maybe desired to prevent discoloration of the baci/- ground area by entrapped developer in .the silica overcoating.
  • Treatment of the copysheet surface with any of the silver stabilizers employed in the photographic art, e.g. quaternary ammonium-halides (such as Triton 400), saccharine, ethylene thiourea, etc. may be-used for this purpose.. f
  • Photoconductive copysheet constructions which can be coated With these film forming silicas have been described above with'referenceto other United States patent applications.
  • Useful highly photoconductive materials include zinc oxide, indium oxide, cadmium sulfide, etc.
  • the photoconductive particulate materials are uniformlyk dispersed in an insulating binder matrix, e.g. a butadienestyrene copolymer, etc; and are usually coated onto an electrically conductive backing, eg. aluminum foil, polyester or other plasticfihn vapor coated with aluminum silver, etc.
  • the backing need not necessarily be electrically conductive if such photoconductive copysheets are to be developed by electrostatic techniques.
  • Sensitizing dyes such as Phosphine R (CI. 788), Patent Blue (CI. 672), xylene cyanol (Cl. 715), etc., are usually included in the photoconductive layer to broaden the spectral response of the photoconductor.
  • the electrolytic image reproduction process in which the copysheets of this invention may be used, has made possible the direct copying of microfilm reproduction of printed pages of books, papers and the like Within a short period of time from initial exposure to the light image to delivery of the completed print.
  • the improved copysheets of this invention are valuable because of their smudge resistance and ability to provide prints or reproductions having significantly higher image density, greater contrast and good definition Without significant loss 'of such other properties as resistance to pinpointing and a relatively rapid development rate.
  • these improved photoconductive copysheets have made photoconductive copysheets suitable for printing continuous tone black and white negatives as Well as for making monochrome prints from continuous tone color negatives.
  • FIGURES 1-3 represent a plot of the diffuse reflection density vs. the log relative exposure for various developers, curves A and B being the uncoated and coated results respectively in each ligure.
  • FIGURE 1 a ten second exposure was used. Electrolytic development was accomplished by immersing the exposed sheets in a developer containing 0.66 wt. percent silver nitrate, 1.8 wt. percent ethylene thiourea, 1 Wt. percent glacial acetic acid, 5 wt. percent magnesium acetate Agreater light penetration and absorption.
  • Photoconductive zinc oxide copysheets (4.6/1 Weight ratio ZnO to Pliolite S7 binder on aluminum laminate backing) Were developed with an aqueous solution containing silver salt and thiourea after an extended exposure to light (i.e. saturation exposure). By controlling development time, varying image densities were obtained up to the maximum value of about 0.9V diffuse reflection density, as shown in FIGURE 4, curve A.
  • Electrolytic development was achieved by immersing the exposed sheets in a developer containing 20l parts by Weight NiCl26H2O, 4 parts ammonium chloride, 4 parts of 28% aqueous ammonium hydroxide, and 200 parts of distilled water (pH of 6.5), the sheets being connected as cathode, and electrolyzing continuously for 5 seconds at a voltage of 25 volts.
  • Electrolytic development was accomplished by immersing the exposed sheets in a developer containing 2 wt. percent silver nitrate, 2 Wt. percent magnesium nitrate and 96% distilled Water, the sheets being connected as cathode, and electrolyzing for 0.5 second at 60 volts.
  • the total current on-time was 10% of the total immersion time, since the electrolysis was cycled to reduce polarization eiiects.
  • the film forming lsilica layer must be Water permeable.
  • a simple test for water permeability may be conducted by coating a magnesium plate With the silica sol to be evaluated and drying the coating either with a hot air current or at ambient room conditions to form a continuous coating on the plate. A few drops of dilute aqueous hydrochloric acid solution is then placed on the coated surface. After a few minutes the coating is physically removed and any etching of the metallic zinc substrate is noted. Water permeability is indicated by such etching.
  • a photoconductive copysheet capable of electrolytic development the improvement which comprises, superimposed on the photoconductive surface thereof, a continuous, glossy, transparent, cohesive and water permeable layer comprising a film forming silica having an average particle size range from about 1 to about 100 millimicrons and a sulfate, said layer having a silica coating weight of from about 0.1 to about 10 grams per square meter and a sulfate content up to about 25 percent by Weight of said silica, said layer being essentially free of alkali metal ions.
  • a photoconductive copysheet capable of electrolytic development the improvement which comprises, superimposed on the photoconductive surface thereof, a continuous, glossy, transparent cohesive and Water perphotoconductive coating.
  • silica having an average particle size range from about 1 tok about 100 millimicrons and a sulfate, said layer having a silica coating weight of about l to about 6 per square meter and a sulfate content up to about 25 percent by Weight ofsad silica, said layer being essentially free of alkali metal ions.
  • a process yfor the preparation of improved photoconductive copysheets capable of electrolytic development which comprises applying over the photoconductive coating thereof a lm Vforming silica sol having an average silica particlersize of rornabout 1 to about 100 millirnicrons, said/silicasol being essentially free ofalkalir Vmetal ions, lin an amount su'flicient to provide a glossy dry 'coating having esesntially no crazing observable by the naked eye and having a coating weight of from about 0.1 to about 10 grams per square meter, and drying said coating vto produce a continuous, glossy, transparent, co-
  • silicafsol is of a sulfate, based on vthe weight ofv said silica.
  • silica sol is anV aqueous Ysol containing up to about 2() percent by Volume of a Water miscible organic solvent.
  • a photoconductive copysheet capable of i' ⁇ an aqueoussol containing up to about 25' weight percentV electrolytic
  • a Vdevelopment which comprises a continuous electrically fgrarnsfper square meter.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • Photoreceptors In Electrophotography (AREA)
US140032A 1961-09-22 1961-09-22 Electrolytic recording sheets Expired - Lifetime US3165458A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
BE622712D BE622712A (de) 1961-09-22
NL283382D NL283382A (de) 1961-09-22
US140032A US3165458A (en) 1961-09-22 1961-09-22 Electrolytic recording sheets
DE19621497009 DE1497009B2 (de) 1961-09-22 1962-08-31 Aufzeichnungsmaterial für elektrophotographische Verfahren
CH1099462A CH418133A (de) 1961-09-22 1962-09-18 Photoleitende Folie für die Bildreproduktion und Verfahren zu ihrer Herstellung
GB35889/62A GB1021885A (en) 1961-09-22 1962-09-20 Photo-conductive sheets and methods of making them
DK412162AA DK104551C (da) 1961-09-22 1962-09-21 Fotoledende folie til billedreproduktion.
FR910054A FR1499851A (fr) 1961-09-22 1962-09-21 Feuilles de reproduction électrolytique
ES0280188A ES280188A1 (es) 1961-09-22 1963-01-16 Mejoras introducidas en la fabricaciën de hojas de copia fotoconductoras particularmente adecuadas para el revelado electrolitico

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US140032A US3165458A (en) 1961-09-22 1961-09-22 Electrolytic recording sheets

Publications (1)

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US3165458A true US3165458A (en) 1965-01-12

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US140032A Expired - Lifetime US3165458A (en) 1961-09-22 1961-09-22 Electrolytic recording sheets

Country Status (9)

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US (1) US3165458A (de)
BE (1) BE622712A (de)
CH (1) CH418133A (de)
DE (1) DE1497009B2 (de)
DK (1) DK104551C (de)
ES (1) ES280188A1 (de)
FR (1) FR1499851A (de)
GB (1) GB1021885A (de)
NL (1) NL283382A (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3409516A (en) * 1963-06-11 1968-11-05 Milton Alden Electrolytic recording paper containing a sequestering agent
US3413201A (en) * 1965-09-10 1968-11-26 Minnesota Mining & Mfg Electrolytic recording sheets
US3432406A (en) * 1960-07-28 1969-03-11 Eastman Kodak Co Photoconductographic material and process of preparation
US3476659A (en) * 1965-07-21 1969-11-04 Fuji Photo Film Co Ltd Electrophotographic imaging and copying process
US3652271A (en) * 1967-09-01 1972-03-28 Addressograph Multigraph Photoelectrostatic recording member
US3914125A (en) * 1964-09-21 1975-10-21 Minnesota Mining & Mfg Diffusion transfer element and method of using same

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA930591A (en) * 1970-04-30 1973-07-24 International Business Machines Corporation Electrophotographic plate

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2244325A (en) * 1940-04-15 1941-06-03 Paul G Bird Colloidal solutions of inorganic oxides
US2886434A (en) * 1955-06-06 1959-05-12 Horizons Inc Protected photoconductive element and method of making same
US2901349A (en) * 1957-05-23 1959-08-25 Haloid Xerox Inc Xerographic plate

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2244325A (en) * 1940-04-15 1941-06-03 Paul G Bird Colloidal solutions of inorganic oxides
US2886434A (en) * 1955-06-06 1959-05-12 Horizons Inc Protected photoconductive element and method of making same
US2901349A (en) * 1957-05-23 1959-08-25 Haloid Xerox Inc Xerographic plate

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3432406A (en) * 1960-07-28 1969-03-11 Eastman Kodak Co Photoconductographic material and process of preparation
US3409516A (en) * 1963-06-11 1968-11-05 Milton Alden Electrolytic recording paper containing a sequestering agent
US3914125A (en) * 1964-09-21 1975-10-21 Minnesota Mining & Mfg Diffusion transfer element and method of using same
US3476659A (en) * 1965-07-21 1969-11-04 Fuji Photo Film Co Ltd Electrophotographic imaging and copying process
US3413201A (en) * 1965-09-10 1968-11-26 Minnesota Mining & Mfg Electrolytic recording sheets
US3652271A (en) * 1967-09-01 1972-03-28 Addressograph Multigraph Photoelectrostatic recording member

Also Published As

Publication number Publication date
DE1497009A1 (de) 1969-04-10
BE622712A (de)
ES280188A1 (es) 1963-03-16
FR1499851A (fr) 1967-11-03
CH418133A (de) 1966-07-31
DK104551C (da) 1966-05-31
DE1497009B2 (de) 1970-01-08
GB1021885A (en) 1966-03-09
NL283382A (de)

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