US3796570A - Electrophotographic,contact-printing process employing a dielectric liquid layer - Google Patents

Electrophotographic,contact-printing process employing a dielectric liquid layer Download PDF

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Publication number
US3796570A
US3796570A US00225607A US3796570DA US3796570A US 3796570 A US3796570 A US 3796570A US 00225607 A US00225607 A US 00225607A US 3796570D A US3796570D A US 3796570DA US 3796570 A US3796570 A US 3796570A
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United States
Prior art keywords
electrophotographic
original
layer
areas
contact
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US00225607A
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English (en)
Inventor
R Comeau
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Kimberly Clark Tissue Co
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Scott Paper Co
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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/225—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 using contact-printing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/22—Processes involving a combination of more than one step according to groups G03G13/02 - G03G13/20

Definitions

  • the present invention relates generally to an improved method for contact printing an electrophotographic material. More particularly, the invention relates to a method comprising Description of the prior art
  • Electrophotographic recording elements are well known in the art and generally comprise a substrate having coated thereon a photoconductive layer.
  • the substrate may be either paper or film which is rendered electrically conductive either by including therein during manufacture a conductive material or by coating thereon a layer of a conductive material.
  • the most commonly employed conductivizing materials include, for example, carbon black and conductive resins.
  • a photoconductive layer generally comprising a photoconductive material in combination with a binder resin, is coated on the substrate.
  • Images are formed on the photoconductive layer by a three-step process comprising charging, exposing, and toning.
  • an overall charge is applied to the photoconductive layer by any of the methods which are now well known in the art including, for example, by rubbing or friction or by the action of ion or electron emission, e.g., by means of a corona discharge.
  • the polarity of the charge on the photoconductive layer can be varied depending upon whether positive or negative prints are desired.
  • a positive print is one which is an exact duplicate of the original being copiedi.e., the imaged areas of the copy correspond to the imaged areas of the original.
  • a negative print is one in which the imaged areas of the copy correspond to the non-imaged, or clear, areas of the originali.e., the copy is the reversed image of the original.
  • the charging step is usually carried out in the dark under which conditions the photoconductive layer will retain the charge deposited thereon.
  • the charged electrophotographic material is selectively, or imagewise, exposed to light.
  • the eifect of the light is to cause the photoconductive layer to become conductive in the areas of the layer which are exposed to light resulting in the dissipation of the charge in those areas.
  • the light may be either reflected from or transmitted through the non-imaged areas of the original to be duplicated. If a nontranslucent original, such as paper, is utilized the light is reflected from the non-imaged areas of the original and strikes the phtoconductive layer. It a translucent original, such as microfilm, is employed the light is directed through the non-imaged areas of the original onto the photoconductive layer.
  • the electrophotographic recording element is exposed to a light and shadow pattern whereby the illuminated areas become conductive and the charge in those areas is discharged while the conductivity of the non-illuminated areas is not changed and they retain their charge.
  • a charge pattern, or latent electrostatic image is formed in certain areas of the electrophotographic recording element.
  • the charge pattern, or latent electrostatic image is rendered visible by any one of several development methods all of which involve the application of a colored material, commonly referred to as a toner, to those areas of the photoconductive layer having the residual charge.
  • a toner employed may be either liquid or dry depending upon whether the pigment used to develop the image is dispersed in a solvent or not. In either case, the pigment adheres to the charged areas of the material resulting in the formation of an image in those areas.
  • Dielectric liquids have previously been suggested for use in connection with electrophotographic recording elements.
  • US. Pat. 2,904,431 issued to Moncrieif-Yeates there is disclosed an electrophotographic charging means wherein a dielectric material is interposed between the electrode or charge source and the material which is to be charged.
  • the dielectric liquid improves the electrical connection between the electrode and the electrophotographic material and conducts electric charges. After charging, the liquid is removed and the material is exposed to produce an electrostatic latent image on the surface of the photoconductive layer.
  • the dielectric liquid is used as a charge transfer medium.
  • Dielectric liquids have also been employed as non-conductive, or insulating, carrier liquids in electrophoretic imaging systems. See, for example, US. Pat. 3,384,566 issued to Clark and US. Pat. 3,485,738 issued to Carreira.
  • contact prints are formed on an electrophotographic material by a method which comprises interposing, during the imagewise exposure step, a layer of a dielectric liquid between the charged electrophotographic recording element and the partially opaque original to be duplicated.
  • contact prints are formed on an electrophotographic material by a method comprising (a) applying an overall charge to an electrophotographic material comprising a base support having a photoconductive layer coated thereon,
  • the electrophotographic recording material utilized in carrying out the present invention may be prepared according to any of the methods which are now well-known in the art.
  • a photoconductive layer comprising a photoconductive material and a binder resin is coated on a suitable base support which may be either paper or film which has been conductivized, as described above.
  • Suitable photoconductors include both organic and inorganic materials.
  • Inorganic photoconductors which may be employed include, for example, cadmium sulfide, cadmium sulfoselenide, zinc oxide, zinc sulfide, sulfur selenium, mercuric sulfide, lead oxide, lead sulfite, cadmium selenide, titanium dioxide, indium trioxide.
  • Useful organic photoconductors include, for example, quinacridones,
  • carboxamides carboxanilides, triazines, anthraquinones,-
  • azo compounds salts and lakes of compounds derived from 9-phenylxanthane, dioxazines, lakes of iiuorescein dyes, pyrenes, phthalocyanines, metal salts and lakes of azo dyes, polyvinyl carbazole, and substituted phenylene diamines.
  • Suitable binder resins include, for example, polystyrene, polystyrene copolymers such as styrene-bn tadiene and styrene butadiene acrylonitrile, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl acetal, polyvinylether, polyacryla'tes, polycarbonates, polyenylene oxide, phenoxy resins, polysulfones and polyesters.
  • polystyrene polystyrene copolymers such as styrene-bn tadiene and styrene butadiene acrylonitrile
  • polyvinyl chloride polyvinylidene chloride
  • polyvinyl acetate polyvinyl acetal
  • polyvinylether polyacryla'tes
  • polycarbonates polyenylene oxide
  • phenoxy resins polysulfones and polyesters.
  • an overall charge is applied to the surface of the photoconductive layer by any of the methods which are well known in the art including, for example, by rubbing or friction or by action of ion or electron emission, e.g., by means of a corona discharge.
  • Dielectric liquids useful in carrying out the present invention are those having a resistivity of at least 10 ohm-centimeters and include, for example, xylene, toluene, carbon tetrachloride, trichloroethylene, cyclohexane, hexane, heptane, kerosene, benzene, Solvesso 100, a narrow cut aromatic solvent having a flash point of F., Solvesso 150, a narrow cut aromatic solvent having a flash point of F. and a boiling range of from 370 F.
  • the dielectric liquid may be applied to the charged surface by any method including, for example, spraying, dipping the charged material in the liquid or cascading.
  • a partially opaque original to be duplicated is placed in contact with said layer. It is especially preferred in carrying out the present invention to also coat the surface of the original with a layer of a dielectric liquid. After the original and the electrophotographic recording element are placed together, improved contact can be obtained by hand-rubbing or in a vacuum frame.
  • the electrophotographic material/dielectric liquid/ original composite is then exposed to light so that the light passes through the non-image, or clear, areas of the original and strikes the photoconductive layer.
  • the electrophotographic material is exposed to a light and shadow pattern whereby the illuminated areas becomq partially conductive and the charge in those areas is discharged while the conductivity of the non-illuminated areas is not changed and they retain their charge.
  • a charge pattern, or latent electrostatic image is formed in those areas of the electrophotographic recording element corresponding to the imaged areas of the original.
  • the partially opaque original is separated from the electrophotographic material bearing the latent electrostatic image.
  • This latent electrostatic image is then developed to form a visible image by toning.
  • the toning may be of either the liquid or dry type and is applied by any of the methods well known in the art.
  • the resulting print exhibits no distortion in the image areas and has a clean background, or non-image, area.
  • the process of the present invention is especially useful in the reproduction of images from partially opaque originals such as microfilm, overhead projectuals and engineering drawings.
  • EXAMPLE I A coating formulation was prepared comprising Grams Toluene 90 Ph'otox 8, a photoconductive zinc oxide available from New Jersey Zinc Co. 150
  • DeSoto E041 a styrenated acrylic resin available from DeSoto Chemical Inc., Chicago, Ill. 50
  • the above formulation was coated by means of a Mayer rod onto a conductivized paper substrate.
  • the resulting electrophotographic material was dried and images were formed thereon in accordance with the following procedure.
  • EXAMPLE H A coating formulation was prepared comprising Grams N,N,N, -tetrabenzyl-p-phenylenediamine 5.0 Butvar 13-76, a polyvinyl butyral resin available The above formulation was coated by means of a Mayor rod onto a polyester film base which had previously been coated with a conductive resin. The resulting electrophotographic material was dried and images were formed thereon in accordance with the following procedure.
  • EXAMPLE III A second sample of the electrophotographic material prepared in Example II was charged, exposed and toned as described in Example 11 except that instead of spraying with Shellsol N the charged material was dipped in Freon TF before the original to be duplicated was placed in contact with the charged surface. The resulting prints also had a uniform density in the imaged areas and a clean background.
  • EXAMPLE IV Another sample of the electrophotographic recording material prepared in Example 11 was also charged, exposed and toned as described in Example 'II except that instead of spraying with Shellsol N, the charged material was cascaded with Solvesso before the original to be duplicated was placed in contact with the charged surface. The resulting prints had a uniform density in the imaged areas and a clean background.
  • an electrophotographic, contact-printing process comprising the improvement which comprises interposing a layer of a dielectric liquid having a resistivity of at least 10 ohmcentimeters between the charged photoconductive layer and the partially opaque original prior to the partially opaque original being brought into contact with the charged photoconductive layer for the imagewise exposure step.
  • the electrophotographic recording element comprises an electrically conductive film base having coated thereon a layer of an organic photoconductor.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrophotography Using Other Than Carlson'S Method (AREA)
US00225607A 1972-02-11 1972-02-11 Electrophotographic,contact-printing process employing a dielectric liquid layer Expired - Lifetime US3796570A (en)

Applications Claiming Priority (1)

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US22560772A 1972-02-11 1972-02-11

Publications (1)

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US3796570A true US3796570A (en) 1974-03-12

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US00225607A Expired - Lifetime US3796570A (en) 1972-02-11 1972-02-11 Electrophotographic,contact-printing process employing a dielectric liquid layer

Country Status (4)

Country Link
US (1) US3796570A (enrdf_load_stackoverflow)
CA (1) CA996989A (enrdf_load_stackoverflow)
FR (1) FR2171379B1 (enrdf_load_stackoverflow)
GB (1) GB1413744A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2656661A1 (de) * 1975-12-15 1977-06-16 Coulter Information Systems Verfahren bzw. einrichtung zur herstellung von kontaktkopien von entwickelten bildern eines filmstreifens
US4173407A (en) * 1975-12-15 1979-11-06 Coulter Information Systems, Inc. Electrophotographic contact duplicating apparatus and method

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2656661A1 (de) * 1975-12-15 1977-06-16 Coulter Information Systems Verfahren bzw. einrichtung zur herstellung von kontaktkopien von entwickelten bildern eines filmstreifens
US4173407A (en) * 1975-12-15 1979-11-06 Coulter Information Systems, Inc. Electrophotographic contact duplicating apparatus and method

Also Published As

Publication number Publication date
FR2171379B1 (enrdf_load_stackoverflow) 1978-03-03
FR2171379A1 (enrdf_load_stackoverflow) 1973-09-21
GB1413744A (en) 1975-11-12
CA996989A (en) 1976-09-14
DE2306983A1 (de) 1973-08-16
DE2306983B2 (de) 1976-06-10

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