EP0823676A1 - Méthode d'impression électrostatique directe sur un substrat isolant - Google Patents

Méthode d'impression électrostatique directe sur un substrat isolant Download PDF

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Publication number
EP0823676A1
EP0823676A1 EP97202357A EP97202357A EP0823676A1 EP 0823676 A1 EP0823676 A1 EP 0823676A1 EP 97202357 A EP97202357 A EP 97202357A EP 97202357 A EP97202357 A EP 97202357A EP 0823676 A1 EP0823676 A1 EP 0823676A1
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EP
European Patent Office
Prior art keywords
conductive layer
toner particles
substrate
conductive
printing
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.)
Withdrawn
Application number
EP97202357A
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German (de)
English (en)
Inventor
Guido Desie
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Agfa Gevaert NV
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Agfa Gevaert NV
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Priority to EP97202357A priority Critical patent/EP0823676A1/fr
Publication of EP0823676A1 publication Critical patent/EP0823676A1/fr
Withdrawn legal-status Critical Current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
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6597—Apparatus which relate to the handling of copy material the imaging being conformed directly on the copy material, e.g. using photosensitive copy material, dielectric copy material for electrostatic printing
    • 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
    • G03G15/34—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the powder image is formed directly on the recording material, e.g. by using a liquid toner
    • G03G15/344—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array
    • G03G15/346—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array by modulating the powder through holes or a slit
    • 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
    • G03G15/65—Apparatus which relate to the handling of copy material
    • G03G15/6582—Special processing for irreversibly adding or changing the sheet copy material characteristics or its appearance, e.g. stamping, annotation printing, punching
    • G03G15/6585—Special processing for irreversibly adding or changing the sheet copy material characteristics or its appearance, e.g. stamping, annotation printing, punching by using non-standard toners, e.g. transparent toner, gloss adding devices
    • 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
    • G03G5/10—Bases for charge-receiving or other layers
    • G03G5/105—Bases for charge-receiving or other layers comprising electroconductive macromolecular compounds
    • G03G5/108—Bases for charge-receiving or other layers comprising electroconductive macromolecular compounds the electroconductive macromolecular compounds being anionic
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/00362—Apparatus for electrophotographic processes relating to the copy medium handling
    • G03G2215/00789—Adding properties or qualities to the copy medium
    • G03G2215/00801—Coating device
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2217/00—Details of electrographic processes using patterns other than charge patterns
    • G03G2217/0008—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member
    • G03G2217/0025—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member where the toner starts moving from behind the electrode array, e.g. a mask of holes

Definitions

  • This invention relates to a method and an apparatus for use in the process of electrostatic printing and more particularly in Direct Electrostatic Printing (DEP).
  • DEP Direct Electrostatic Printing
  • electrostatic printing is performed directly from a toner delivery means on a substrate by means of an electronically addressable printhead structure.
  • the toner or developing material is deposited directly in an imagewise way on a receiving substrate, the latter not bearing any imagewise latent electrostatic image.
  • the substrate is an intermediate endless flexible belt (e.g. aluminium, polyimide etc.)
  • the imagewise deposited toner must be transferred onto another final substrate. If, however, the toner is deposited directly on the final receiving substrate, a possibility is fulfilled to create directly the image on the final receiving substrate, e.g. plain paper, transparency, etc. This deposition step is followed by a final fusing step.
  • the method makes the method different from classical electrography, in which a latent electrostatic image on a charge retentive surface is developed by a suitable material to make the latent image visible. Further on, either the powder image is fused directly to said charge retentive surface, which then results in a direct electrographic print, or the powder image is subsequently transferred to the final substrate and then fused to that medium. The latter process results in an indirect electrographic print.
  • the final substrate may be a transparent medium, opaque polymeric film, paper, etc.
  • DEP is also markedly different from electrophotography in which an additional step and additional member is introduced to create the latent electrostatic image. More specifically, a photoconductor is used and a charging/exposure cycle is necessary.
  • a DEP device is disclosed in e.g. US-P 3,689,935.
  • This document discloses an electrostatic line printer having a multi-layered particle modulator or printhead structure comprising :
  • Selected potentials are applied to each of the control electrodes while a fixed potential is applied to the shield electrode.
  • An overall applied propulsion field between a toner delivery means and an image receiving substrate projects charged toner particles through a row of apertures of the printhead structure.
  • the intensity of the particle stream is modulated according to the pattern of potentials applied to the control electrodes.
  • the modulated stream of charged particles impinges upon a receiving member substrate, interposed in the modulated particle stream.
  • the receiving member substrate is transported in a direction orthogonal to the printhead structure, to provide a line-by-line scan printing.
  • the shield electrode may face the toner delivery means and the control electrode may face the receiving member substrate.
  • a DC field is applied between the printhead structure and a single back electrode on the receiving member support.
  • This propulsion field is responsible for the attraction of toner to the receiving member substrate that is placed between the printhead structure and the back electrode.
  • the printing device as described in US 3,689,935 is very sensitive to changes in distances from the toner application module towards said shield electrode, leading to changes in image density. Moreover, since the electrostatic characteristics of the final image receiving member are subject to changes in environmental conditions, the resulting image density is also dependent upon the environmental conditions. If a very thick isolating substrate is used as final image receptive member, then no density at all is possible using a printing device according to US 3,689,935.
  • DEP Direct Electrostatic Printing
  • said conductive layer has a surface resistance equal to or lower than 10 14 ⁇ /square.
  • said conductive layer comprises an organic conductive compound.
  • a DEP device for printing on an insulating image receiving substrate comprising:
  • Fig. 1 is a schematic illustration of a possible embodiment of a DEP device according to the present invention.
  • an intermediate image receptive member as described in e.g. UP 5,305,026, US 5,353,105 and EP-A 743 572 it is possible to deposit an image upon said intermediate image receptive member, followed by transferring or transfusing said intermediate toner image to said final image receptive member.
  • This final image receiving member can then be either conductive of insulating. In this case, however, the surface topography of said final image receptive member has to be such that intimate contact between said intermediate image receptive member and said final image receptive member is possible.
  • any final image receptive member irrespective of its surface topography and conductivity, by using a method as described in the object of the invention: i.e. treatment of said insulating final image receiving member (hereinafter called insulating substrate) before printing by applying a conductive layer on top of said substrate, contacting said conductive layer via a conductive charge applying device that is connected to a voltage source, and lastly printing images on said charged conductive layer. After fusing an image of excellent sharpness and quality is obtained upon said final image receiving member.
  • insulating substrate insulating final image receiving member
  • the DC field for attracting charge toner particles from the toner delivery means to the final image receiving substrate is created between said toner delivery means and said conductive layer applied on said insulating substrate.
  • insulating substrates are defined as substrates that are at least 200 ⁇ m thick (even plain paper with such a thickness is insulating in the sense of this document) or that are plastics, e.g. polyesters, addition polymers (polyvinylchloride, polypropylene, polystyrene, etc), polycarbonates, etc.
  • the surface resistance expressed in ⁇ /square (ohm/sq.) of the above defined conductive layer is measured according to test procedure A as follows :
  • Said conductive layer can be applied either off-line (i.e. outside of the printing device) or on-line in a "conductive layer applying station" incorporated in the printing device.
  • the present invention includes thus a method for DEP printing comprising the steps of :
  • the conductive layer can, in the methods according to this invention, be applied on top of said insulating substrate by any means known in the art. It can be coated, sprayed, brushed, etc, on said insulating substrate. When the application of said conductive layer proceeds on-line, it is preferred to spray coat it.
  • the application of said conductive layer proceeds preferably from a dilute composition (solution, emulsion, dispersion, polymeric latex, etc) comprising conductive compounds. Any conductive compound known to those skilled in the art can be used in the method of the present invention.
  • Said conductive compounds can be particulate materials such as small conductive beads (e.g,iron beads) conductive anorganic material (e.g. SnO 2 , V 2 O 5 , etc), conducting polymers both ionically and electronically conductive or a mixture of both.
  • Preferred conductive compounds for use according to the present invention are transparent or semi-transparent conductive polymers.
  • Examples of preferred ionically conducting polymers are acidic polymers, preferably polymeric carboxylic or sulphonic acids.
  • Examples of such polymeric acids are polymers containing repeating units selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, vinyl sulphonic acid and styrene sulphonic acid or mixtures thereof.
  • Polymers of this type, useful in the present invention have been disclosed in e.g. US 5,254,448, US 5,4045,441 and EP-A 437 728.
  • Polyesters comprising moieties comprising sulphonic acid group e.g., a polyester comprising moieties derived from sulphoisophthalic acid
  • Examples of preferred electronically conductive polymers are polyaniline, polypyrrole, polythiophene, etc.
  • Preferred electronically conductive polymers are polythiophenes.
  • Useful polythiophenes have been described in, e.g. EP-A 203 438, EP-A 253 594, EP-A 257 573, US 4,929,383 and EP-A 505,955.
  • Preferred, for use in the present invention, among the electronically conductive polymers is a polythiophene with conjugated polymer backbone in the presence of a polymeric polyanion compound.
  • polythiophene having structural units corresponding to the following formula I : in which : each of R 1 and R 2 independently represents hydrogen or a C 1-4 alkyl group or together represent an optionally substituted C 1-4 alkylene group or a cycloalkylene group.
  • R 1 and R 2 independently represents hydrogen or a C 1-4 alkyl group or together represent an optionally substituted C 1-4 alkylene group or a cycloalkylene group.
  • Oxidizing agents suitable for the oxidative polymerization of pyrrole are described, for example, in J. Am. Soc. 85 , 454 (1963). Inexpensive and easy-to-handle oxidizing agents are preferred such as iron(III) salts, e.g. FeCl 3 , Fe(ClO 4 ) 3 and the iron(III) salts of organic acids and inorganic acids containing organic residues, likewise H 2 O 2 , K 2 Cr 2 O 7 , alkali or ammonium persulfates, alkali perborates, potassium permanganate and copper salts such as copper tetrafluoroborate.
  • iron(III) salts e.g. FeCl 3 , Fe(ClO 4 ) 3 and the iron(III) salts of organic acids and inorganic acids containing organic residues, likewise H 2 O 2 , K 2 Cr 2 O 7 , alkali or ammonium persulfates, alkali perborates, potassium per
  • Suitable polymeric polyanion compounds for use in the presence of said polythiophenes are provided by acidic polymers in free acid or neutralized form.
  • the acidic polymers are preferably polymeric carboxylic or sulphonic acids. Examples of such polymeric acids are polymers containing repeating units selected from the group consisting of acrylic acid, methacrylic acid, maleic acid, vinyl sulphonic acid and styrene sulphonic acid or mixtures thereof.
  • the anionic (acidic) polymers used in conjunction with the dispersed polythiophene polymer have preferably a content of anionic groups of more than 2% by weight with respect to said polymer compounds to ensure sufficient stability of the dispersion. Suitable acidic polymers or corresponding salts are described e.g.
  • the polymeric polyanion compounds may consist of straight-chain, branched chain or cross-linked polymers.
  • Cross-linked polymeric polyanion compounds with a high amount of acidic groups are swellable in water and are named microgels.
  • microgels are disclosed e.g. in US-P 4,301,240, US-P 4,677,050 and US-P 4,147,550.
  • a preferred polyanion compound for combining with a polythiophene in order to provide a solution to apply a conductive layer according to this invention, is polystyrenesulphonic acid.
  • conductive polymers with very low light absorption preferably clear, transparent polymers are used
  • the characteristics of the final image receptive substrate are not changed. This is very interesting in case an additional image is printed using said DEP method upon a final image receptive member (the insulating substrate) that already has some image information.
  • the word "clear” means herein not giving, in a wavelength range extending from 400 to 700 nm, a visible density, said visible density being defined as less than 15 % light reduction integrated over that wavelength range.
  • the composition for applying a thin transparent conductive layer upon said insulating substrate can comprise any solvent, binder and additives (e.g. preservatives, viscosity regulators, surfactants, etc) known in the art.
  • the properties of said composition for applying a thin transparent conductive layer upon said insulating substrate can be adapted to the chemical and physical properties of the insulating substrate on which the image has to be printed.
  • said composition can comprise solvents ranging from water, ethanol, propanol, MEK, toluene, etc. Binders can be added so that an homogeneous coating thickness can be obtained upon said final image receptive member (insulating substrate).
  • viscosity regulators any material known to those skilled in the art can be used.
  • the surface tension of said composition can be tuned by the incorporation of any surfactant known to those skilled in the art, and includes anionic, cationic or non-ionic tensides.
  • the composition for applying a thin transparent conductive layer upon said insulating substrate can further, if desired, comprise filler material such as fine particles, UV-absorbers, anti-foam additives, etc.
  • a very suitable composition for a conductive layer according to the present invention has been described in US 5,391,472, that is incorporated herein by reference.
  • a transparent antistatic layer wherein said layer contains (1) a polythiophene with conjugated polymer backbone in the presence of a polymeric polyanion compound and (2) at least one latex polymer having hydrophilic functionality has been disclosed.
  • latex polymer is understood a polymer or copolymer that is applied as an aqueous dispersion (latex) of particles of said polymer or copolymer.
  • hydrophilic functionality is meant a chemical group having affinity for water e.g. a sulphonic acid or carboxylic acid group preferably in salt form e.g. an alkali metal salt group.
  • the "latex polymer” applied in admixture with said polythiophene and polymeric anion compound is preferably a copolyester containing sulphonic acid groups in salt form, but other polyesters, such as the copolyesters having hydrophilic functionality as described e.g. in US-P 3,563,942, 4,252,885, 4,340,519, 4,394,442 and 4,478,907, may be used likewise.
  • Preferred copolyesters contain a certain amount of sulphonic acid groups in salt form (ref. GB-P 1,589,926) and as described in US-P 4,478,907 and EP 78 559 and for raising their glass transition temperature (Tg) contain an amount of particular co-condensated cross-linking agent(s).
  • Such copolyesters contain e.g. recurring ester groups derived from ethylene glycol and an acid mixture containing (i) terephthalic acid, (ii) isophthalic acid, (iii) 5-sulphoisophthalic acid whose sulpho group is in salt form and (iv) a polyfuctional acid producing cross-links.
  • the copolyester is a copolyester containing recurring ester groups derived from ethylene glycol and an acid mixture containing terephthalic acid, isophthalic acid and 5-sulphoisophthalic acid whose sulpho group is in salt form, said acid mixture consisting essentially of from 20 to 60 mole % of isophthalic acid, 6 to 10 mole % of said sulphoisophthalic acid, 0.05 to 1 mole % of cross-linking agent being an aromatic polycarboxylic acid compound having at least three carboxylic acid groups or corresponding acid generating anhydride or ester groups, the remainder in said acid mixture being terephthalic acid.
  • the present invention comprises also a DEP device for printing on an insulating image receiving substrate, comprising :
  • Said conductive layer is a conductive layer having a conductivity and composition as described herein before.
  • Said substrate can be any substrate, but the invention is well suited to be used for printing an insulating substrate.
  • the substrate can have any shape, e.g., it can be in sheet form, in web form, it can be moulded articles, etc. When the substrate is a moulded article, it can have any shape and any surface topology. It can e.g. be cylindrical with a smooth surface, it can be flat with a ondulated surface, etc.
  • Said means for applying said conductive layer on said substrate can be any means known in the art to apply a composition comprising a conductive compound (conductive composition) on a substrate.
  • Said means for applying said conductive composition can be rollers, wicks, sprays, etc. When said means for applying said conductive composition are rollers, it may be split rollers.
  • Very suitable means for applying said conductive composition are supply rollers with a surface in NOMEX-felt (NOMEX is a trade name of Du Pont de Nemours, Wilmington, US) as described in article titled "Innovative Release Agent Delivery Systems" by R. Bucher et al. in The proceedings of IS&T's Eleventh International Congress on Advances in Non-Impact Printing Technologies, page 219 - 222.
  • the conductive composition can be delivered to the image directly by supply rollers as described above, or over an intermediate roller, which distributes the composition even more evenly over the substrate.
  • conductive compositions are spraying means, e.g. an air-brush.
  • an air brush is preferred when the substrate to be printed is a moulded article, showing a relief surface.
  • Said means for applying an electrical field between said conductive layer and a toner delivery means comprise means for contacting said conductive layer and connecting it to an appropriate voltage source or to the earth.
  • Said means for contacting said conductive layer comprise preferably a conductive brush.
  • the hairs of said brush can be metallic fibres, carbon fibres, etc.
  • said brush contacts said conductive layer only at one or more of the edges of the surface to be printed. Since said brush when only contacting edges of the surface to be printed, it does not touch the image parts, that can be made up with not yet fused or fixed toner particles, so the device according to the present invention can be used for printing multiple images (multiple monochrome image or multiple images (e.g. a yellow, magenta, cyan and black image) to form a full colour image on top of each other and fixing all layers of deposited toner particles at once.
  • the means for contacting said conductive layer can also be contacting rollers made of conductive material, preferably metal as aluminum, stainless steel.
  • a roller it is preferred that the surface of such a roller is formed by a conductive elastomeric compound, e.g., by a rubber filled with carbon black.
  • FIG. 1 A non limitative example of a device for implementing a PEP method according to the present invention is shown in figure 1 and comprises :
  • V3 is selected, according to the modulation of the image forming signals, between the values V3 0 and V3 n , on a timebasis or grey-level basis.
  • Voltage V4 is applied to the conductive charge applying device. In other embodiments of the present invention multiple voltages V2 0 to V2 n can be used.
  • the magnetic brush assembly (103) preferentially used in a DEP device according to an embodiment of the present invention can be either of the type with stationary sleeve and rotating core or of the type with rotating core and rotating sleeve.
  • carrier particles such as described in EP-A 675,417 can be used in a preferred embodiment of the present invention.
  • any kind of two-component toner particles, black, coloured or colourless, can be used in a DEP device according to the present invention. It is preferred to use toner particles as disclosed in EP-A 715 218, that is incorporated by reference.
  • a DEP device making use of the above mentioned marking particles can be addressed in a way that enables it to give black and white. It can thus be operated in a "binary way", useful for black and white text and graphics and useful for classical bilevel halftoning to render continuous tone images.
  • a DEP device is especially suited for rendering an image with a plurality of grey levels.
  • Grey level printing can be controlled by either an amplitude modulation of the voltage V3 applied on the control electrode 106a or by a time modulation of V3. By changing the duty cycle of the time modulation at a specific frequency, it is possible to print accurately fine differences in grey levels. It is also possible to control the grey level printing by a combination of an amplitude modulation and a time modulation of the voltage V3, applied on the control electrode.
  • a printhead structure (106) was made from a polyimide film of 50 ⁇ m thickness, double sided coated with a 9 ⁇ m thick copper film.
  • the printhead structure (106) had four rows of printing apertures.
  • a square shaped control electrode (106a) was arranged around each aperture. Each of said control electrodes was individually addressable from a high voltage power supply.
  • a common shield electrode (106b) was present on the front side of the printhead structure, facing the toner delivery means.
  • the printing apertures had an aperture diameter of 100 ⁇ m.
  • the total width of the square shaped copper control electrodes was 250 ⁇ m, their internal aperture width was also 100 ⁇ m.
  • the width of the aperture in the common shield electrode was 400 ⁇ m.
  • Said printhead structure was fabricated in the following way. First of all the control electrode pattern was etched by conventional copper etching techniques. Then the shield electrode pattern was etched by conventional copper etching techniques. The apertures were made by a step and repeat focused excimer laser making use of the control electrode patterns as focusing aid. After excimer burning the printhead structure was cleaned by a short isotropic plasma etching cleaning. Finally a thin coating of PLASTIK70 (tradename), commercially available from Griffin Chemie, was applied over the control electrode side of said printhead structure.
  • PLASTIK70 tradename
  • the toner delivery means The toner delivery means
  • the toner delivery means (101) was a stationary core / rotating sleeve type magnetic brush.
  • the magnetic brush assembly (103) was constituted of the so called magnetic roller, which in this case contained inside the roller assembly a magnetic core, showing 9 magnetic poles of 500 Gauss magnetic field intensity with a fall-off zone.
  • the magnetic roller contained also a sleeve, fitting around said magnetic core, and giving to the magnetic brush assembly an overall diameter of 20 mm.
  • the sleeve was made of finely roughened stainless steel.
  • a doctoring blade was used to meter a small amount of developer onto the surface of said magnetic brush assembly.
  • the sleeve was rotating at 100 rpm.
  • the magnetic brush assembly (103) was connected to an AC power supply with a square wave oscillating field of 600 V at a frequency of 3.0 kHz with 0 V DC-offset.
  • a macroscopic "soft" ferrite carrier consisting of a MgZn-ferrite with average particle size 50 ⁇ m, a magnetisation at saturation of 29 emu/g was provided with a 1 ⁇ m thick acrylic coating. The material showed virtually no remanence.
  • the toner used for the experiment had the following composition : 97 parts of a co-polyester resin of fumaric acid and propoxylated bisphenol A, having an acid value of 18 and volume resistivity of 5.1 x 10 16 ohm.cm was melt-blended for 30 minutes at 110° C in a laboratory kneader with 3 parts of Cu-phthalocyanine pigment (Colour Index PB 15:3).
  • a resistivity decreasing substance - having the following structural formula : (CH 3 ) 3 N + C 16 H 33 Br - - was added in a quantity of 0.5 % with respect to the binder. It was found that - by mixing with 5 % of said ammonium salt - the volume resistivity of the applied binder resin was lowered to 5x10 14 ⁇ .cm.
  • the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
  • the resulting particle size distribution of the separated toner measured by Coulter Counter model Multisizer (tradename), was found to be 6.3 ⁇ m average by number and 8.2 ⁇ m average by volume.
  • the toner particles were mixed with 0.5 % of hydrophobic colloidal silica particles (BET-value 130 m 2 /g).
  • An electrostatographic developer was prepared by mixing said mixture of toner particles and colloidal silica in a 4 % ratio (w/w) with carrier particles.
  • the tribo-electric charging of the toner-carrier mixture was performed by mixing said mixture in a standard tumbling set-up for 10 min.
  • the printing device The printing device
  • a conductive coating was applied by an air brush (111) that sprayed a thin coating of a composition comprising a conductive polymer.
  • Said composition consisted of (all parts in weight) : 40 parts of acetone, 50 parts of methanol, 1 part of polyvinylalcohol, 4 parts of water and 5 parts of a polythiophene/polyanion mixture (PEDT).
  • the latter mixture (dispersion) was prepared as follows : Into 1000 ml of an aqueous solution of 7 g of polystyrene sulphonic acid (109 mmol of SO 3 H groups) with number-average molecular weight (Mn) 40,000, were introduced 12.9 g of potassium peroxidisulfate (K 2 S 2 O 8 ), 0.1 g of Fe 2 (SO 4 ) 3 and 2.8 g of 3,4-ethylenedioxy-thiophene. The thus obtained reaction mixture was stirred for 24 h at 20 °C and subjected to desalting.
  • the above prepared reaction mixture was stirred for 6 hours at room temperature in the presence of a granulated weak basic ion exchange resin LEWATIT H 600 (tradename of the Bayer Company of Leverkusen, Gemany) and strongly acidic ion exchanger LEWATIT S 100 (tradename of the Bayer Company of Leverkusen, Germany).
  • the ion exchange resins were filtered off and the potassium ion and sulphate ion content were measured which were respectively 0.4 g K + and ⁇ 0.1 g (SO 4 ) 2- per litre.
  • the means for providing an electrical field between the conductive layer and the toner delivery means was a brush with carbon-black filled conductive hairs and was placed at 50 mm from the printing nip. Said brush (105) was connected to a high voltage power supply of +1500 V. To the sleeve of the magnetic brush an AC voltage of 600 V at 3.0 kHz was applied, without DC offset.
  • a printing configuration as described in example 1 was used, except for the fact that as substrate, polyester foil with typical photographic subbing layers (Example 2), a polycarbonate foil (Example 3), and a PVC foil (Example 4) was used.
  • example 1 The procedure of example 1 was repeated, except for the fact that as substrate a linoleum foil with carpet design was used and that instead of PEDT a commercially available conductive spray (ANTISTATIC 100, tradename of Mais Chemie) was used.
  • ANTISTATIC 100 commercially available conductive spray
  • comparative examples C1 and C2 the same configuration as described in example 1 was used except for the fact that the conductive brush (105) was grounded.
  • comparative example CE1 polyester foil was used as substrate as described in example 1
  • comparative example 2 the same substrate as described in example 5 was used.
  • comparative examples 3 and 4 the same configuration as described in examples 1 and 5 was used, except for the fact that no conductive layer was applied to said substrates.
  • the conductive composition as described in example 1 is applied off-line to a 300 ⁇ m polyethyleleneterephthalate film, in various thicknesses so as to provide substrates with varying lateral resistance.
  • printing proceeded with a DEP device as described in example 1.
  • the sharpness and the maximum optical density reached were evaluated as described above.
  • the results, together with the lateral resistance ( ⁇ /square) are given in table 2.
  • alterations can be made to this concept of printing without departing from the spirit of the present invention.
  • any method of charging the surface of a non-conducting receptive member can be used according to the same object of the present invention.
  • Surface charging can e.g. be performed by charged contact rollers, corona or scorotron devices, frictional contact charging means, etc...
EP97202357A 1996-08-08 1997-07-25 Méthode d'impression électrostatique directe sur un substrat isolant Withdrawn EP0823676A1 (fr)

Priority Applications (1)

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EP97202357A EP0823676A1 (fr) 1996-08-08 1997-07-25 Méthode d'impression électrostatique directe sur un substrat isolant

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EP96202228 1996-08-08
EP96202228 1996-08-08
EP97202357A EP0823676A1 (fr) 1996-08-08 1997-07-25 Méthode d'impression électrostatique directe sur un substrat isolant

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1065572A1 (fr) * 1999-06-28 2001-01-03 Xerox Corporation Revêtement de polythiophène pour un composant xérographique
WO2001065896A1 (fr) * 2000-03-02 2001-09-07 Array Ab Procede et dispositif d'impression electrostatique directe pour la fabrication de cartes a circuits imprimes
US11028299B2 (en) * 2013-11-19 2021-06-08 Mitsubishi Polyester Film, Inc Anti-powdering and anti-static polymer film for digital printing

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2238593A1 (en) * 1973-07-24 1975-02-21 Siemens Ag Electrostatic printing machine - covers paper with insulating or photoconductive material before printing
US4001838A (en) * 1974-04-01 1977-01-04 Electroprint, Inc. Methods and apparatus for cleaning paper in a high speed electrostatic printing apparatus
US5305026A (en) * 1990-10-17 1994-04-19 Brother Kogyo Kabushiki Kaisha Image recording apparatus having toner particle control member
EP0675417A1 (fr) * 1994-03-29 1995-10-04 Agfa-Gevaert N.V. Procédé et dispositif d'impression électrostatique directe (DEP)

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2238593A1 (en) * 1973-07-24 1975-02-21 Siemens Ag Electrostatic printing machine - covers paper with insulating or photoconductive material before printing
US4001838A (en) * 1974-04-01 1977-01-04 Electroprint, Inc. Methods and apparatus for cleaning paper in a high speed electrostatic printing apparatus
US5305026A (en) * 1990-10-17 1994-04-19 Brother Kogyo Kabushiki Kaisha Image recording apparatus having toner particle control member
EP0675417A1 (fr) * 1994-03-29 1995-10-04 Agfa-Gevaert N.V. Procédé et dispositif d'impression électrostatique directe (DEP)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1065572A1 (fr) * 1999-06-28 2001-01-03 Xerox Corporation Revêtement de polythiophène pour un composant xérographique
WO2001065896A1 (fr) * 2000-03-02 2001-09-07 Array Ab Procede et dispositif d'impression electrostatique directe pour la fabrication de cartes a circuits imprimes
US11028299B2 (en) * 2013-11-19 2021-06-08 Mitsubishi Polyester Film, Inc Anti-powdering and anti-static polymer film for digital printing

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