EP0379673B1 - Elément pour l'enregistrement par électro-érosion avec une résistance modifiée à la corrosion - Google Patents

Elément pour l'enregistrement par électro-érosion avec une résistance modifiée à la corrosion Download PDF

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Publication number
EP0379673B1
EP0379673B1 EP19890121803 EP89121803A EP0379673B1 EP 0379673 B1 EP0379673 B1 EP 0379673B1 EP 19890121803 EP19890121803 EP 19890121803 EP 89121803 A EP89121803 A EP 89121803A EP 0379673 B1 EP0379673 B1 EP 0379673B1
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EP
European Patent Office
Prior art keywords
layer
conductive
electroerosion
conductive layer
dichromate
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Expired - Lifetime
Application number
EP19890121803
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German (de)
English (en)
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EP0379673A3 (en
EP0379673A2 (fr
Inventor
Ali Afzali-Ardakani
Keith S. Pennington
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International Business Machines Corp
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International Business Machines Corp
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Publication of EP0379673A3 publication Critical patent/EP0379673A3/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
    • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
    • B41M5/24—Ablative recording, e.g. by burning marks; Spark recording
    • B41M5/245—Electroerosion or spark recording

Definitions

  • the invention relates to electroerosion printing and to recording materials characterized by an improved hydrophilic, conductive or resistive lubricant top-coat, especially for use in the production of direct offset masters or direct negative applications.
  • Electroerosion printing is a well-known technique for producing markings, such as, letters, numbers, symbols, patterns, such as, circuit patterns, or other legible or coded indicia on recording material in response to an electric signal which removes or erodes material from the surface of the recording material as the result of spark initiation.
  • the surface which is eroded or removed to provide such indicia on the recording material is usually a thin film of conductive material which is vaporized in response to localized heating associated with sparking (arcing) initiated by applying an electric current to an electrode in contact with the surface of a recording material comprising the thin conductive film on a flexible nonconductive backing or support.
  • the thin conductive film is usually a thin film of vaporizable metal, such as, aluminum.
  • Electroerosion printing is effected by the movement of a stylus or a plurality of styli relative to the surface of specially prepared recording media. Electrical writing signals are fed to the stylus to provide controlled electrical pulses which generate sparks at the surface of the recording material to selectively heat and remove by evaporation a layer of the recording material; the locations from which material is removed correspond to the indicia or images which are to be recorded.
  • the stylus is moved relatively to a surface of the recording material and in contact with the removable layer, e.g., a thin film of vaporizable material, usually a metal, such as aluminum.
  • the removable layer e.g., a thin film of vaporizable material, usually a metal, such as aluminum.
  • U.S. Patent 4,622,262 describes the use of graphite dispersed in a water insoluble polymeric binder, for example, ethyl cellulose. Although the corrosion resistance of the film is very good, the material cannot readily be used as direct offset plate because the surface of the material is hydrophobic and the top coat can not be easily removed from the surface.
  • U.S. Patent 4,617,579 describes the use of a hydrophilic-water soluble binder (hydroxy ethyl cellulose or the like) in the top coat.
  • a hydrophilic-water soluble binder hydroxy ethyl cellulose or the like
  • DNP direct negative/direct plate
  • U.S. Patent 4,567,490 describes the use of fluorinated graphite and Teflon with or without addition of graphite. Although the corrosion resistance of DNP materials coated with these fluorinated compounds increases due to their low conductivity, the print quality is poor.
  • an electroerosion recording material comprising a support of non-condcutive Mylar, an intermediate base layer of a hard urethane cross-linked CAB filled with silica particles, an aluminum conductive layer and a lubricant overlayer of a water insoluble but water wettable partially cross-linked polymer containing conductive lubricant particles of graphite.
  • EP-A-147 642 discloses an electroerosion recording medium which comprises a non-conductive support, a hard, abrasion resistant layer, comprising an organic polymeric matrix containing an inorganic particulate material, a thin conductive film, and an abrasion resistant overlayer that comprises a solid conductive lubricant dispersed in an organotitanium reagent modified polymer system.
  • the polymer system comprises a cross-linked polymer formed by interaction of a hydroxyl group-containing polymer with one or more organotitanium reagents.
  • improved electroerosion recording materials can be prepared by providing the aluminum surface of such materials with a protective layer of solid conductive lubricant dispersed in a water insoluble hydrophilic crosslinked polymer matrix.
  • the recording medium according to this invention provides use as a defect-free "direct negative” and/or “direct offset printing master” and thus has the advantage of process simplification by eliminating the need for removal of the overlayer after electroerosion recording and prior to use on the printing press as commonly practiced with conventional recording media.
  • a further advantage of the unique protective coatings described herein is realized from application using aqueous dispersions of polymer- particulate compositions and thus avoiding the use of organic solvents.
  • the conductive solid lubricant may be selected from the various conductive particulate lubricants disclosed in U.S. 4,622,262.
  • the overlayer disclosed herein can be applied directly to the surface of electroerosion recording materials.
  • One object of the invention is to produce electroerosion recording materials of improved resistance to stylus scratching by use of the special lubricating coatings of this invention.
  • Another object is to provide an abrasion-resistant recording material suitable for generation of a high quality "direct negative” which also functions as a “direct offset printing master” with no extra step involved after electroerosion recording.
  • Another object of the invention is to provide a superior lubricant composition which can also exhibit improved contrast when used to produce direct-negatives by electroerosion printing.
  • a dark graphite/polymer film serves to help block light that may be partially transmitted through the thin conductive film, e.g., a thin aluminum film.
  • a further object of the present invention is to provide a lubricant composition which does not have to be removed in the production of offset masters.
  • Another object of this invention is to provide a superior lubricant composition which has improved corrosion resistance to fingerprinting or storage in a humid environment.
  • Yet another object is to provide improved electroerosion recording material having a thin, uniform, and adherent overcoat for the aluminum film for protection against damage during storage and handling.
  • the present invention generally comprises electroerosion recording materials consisting of a flexible support preferably with an abrasion-resistant, ink-receptive layer of polymer-particulate compositions, and an electroerodible metal film such as Al with a protective coating comprising lubricating particles of good electric conductivity in special types of organic polymeric binders.
  • Electroerosion materials for use as direct-negatives or direct masters can be prepared utilizing this invention.
  • the lubricating layer should have a density between about 2 and 30 micrograms per square centimeter since lower concentrations give inadequate lubrication and higher concentrations are too thick for good writing at low writing voltages (about 50 V) and short pulse lengths (about 3 microseconds). If more energy is applied by increasing the voltage of the writing pulse and increasing the pulse length, thicker films can be used.
  • the lubricating agent binder ratio should be adjusted to avoid flake-off of the lubricating agent.
  • conductive laminar solids may be used as the particulate conductive lubricant agent for the protective layer.
  • Preferred materials are concentrated aqueous colloidal suspension of graphite/purified carbon with average particle size less than 1 ⁇ m available from Superior Graphite Co., Acheson Colloid Co., or similar products from Graphite Product Corp.
  • materials which are expected to be useful include, for example, carbon black of mean particle diameter 0.02 ⁇ m, solids such as ZnO, TiO2, MoS2, WS2, VSe2, TaSe2, CdS, Sb2O3 and TaS2; other soft compounds such as AgI, PbO, Pb(OH)2, MoO, ZnI2, and PbCO3; and soft metal particles such as Sn, Cu, Ag, Pb, Au, Bi, Zn, Al, etc.
  • solids such as ZnO, TiO2, MoS2, WS2, VSe2, TaSe2, CdS, Sb2O3 and TaS2
  • other soft compounds such as AgI, PbO, Pb(OH)2, MoO, ZnI2, and PbCO3
  • soft metal particles such as Sn, Cu, Ag, Pb, Au, Bi, Zn, Al, etc.
  • a typical structure comprises a flexible support such as polyethylene terephthalate (Mylar) with an abrasion-resistant base layer of polymer-particulate matrix which is preferably cross-linked, a thin conductive electroerodible film such as Al and a protective overlayer consisting of solid lubricants dispersed in a hydrophobic polymer matrix.
  • a flexible support such as polyethylene terephthalate (Mylar) with an abrasion-resistant base layer of polymer-particulate matrix which is preferably cross-linked, a thin conductive electroerodible film such as Al and a protective overlayer consisting of solid lubricants dispersed in a hydrophobic polymer matrix.
  • the lubricating top coat of this invention consists of a solid lubricant and a polymeric binder that glues the solid lubricant to the aluminum film so that it can not be easily removed either by hand or in the printer. Because electroerosion printing requires that electric current be passed from the printer head (array of 32 tungsten electrodes) to the aluminum film, the solid lubricant on the material has to be somewhat conductive and that is the reason that graphite or a mixture of graphite (conductive) and Teflon (non-conductive) is used as solid lubricant. The reason for lubricant is to reduce scratching (some times referred to as burnishing) of the aluminum film in the electroerosion process.
  • the binder in the top coat which is used to glue the lubricant to aluminum plays an important role in the wettability of the materials.
  • the surface of the material In order to be able to use the material as direct offset plate, the surface of the material must be hydrophilic.
  • the water soluble cellulosic (hydroxy ethyl cellulose) materials make the aluminum surface much more susceptible to corrosion by finger prints or humidity of the environment. But if the binder is chosen from water insoluble polymeric materials (like ethyl cellulose), which reduces the chances of the corrosion of the aluminum film, the materials cannot be used as direct plate.
  • This invention describes choice of a water soluble-hydrophilic binder which after partial crosslinking with potassium dichromate becomes water insoluble (while maintaining its hydrophilicity) and which can be removed easily by conventional etchants, and therefore increases the corrosion resistance of the materials at the same time it retains its dual application as direct negative and direct plate. Furthermore, this invention describes the reaction of dichromate with aluminum film which makes a conversion layer on top of the aluminum which results in significant reduction of scratching (burnishing).
  • FIG. 1 illustrates schematically an electroerosion printing system 1 which includes a source of electrical energy 2, which is connected with writing control means 3 for controlling the flow (voltage and pulse length) of electrical current to styli 4 which are electrodes which contact the surface of the electroerosion recording material 5.
  • Means are provided for moving the styli 4 relative to and in contact with the surface of the recording material 5.
  • the styli 4 move relative to the recording material 5 and the writing control means 3 direct pulses of current to the styli of sufficient voltage to cause arcing and evaporation of a conductive layer of the material, there can be recorded desired information, patterns and graphics of any kind. It is during the movement of the styli over and in contact with the surface of the recording material that the thin film on the surface of the recording 15 material is liable to be scratched and abraded resulting in poor writing quality and perhaps the recording of erroneous information.
  • the electroerosion recording material of this invention 6 is shown in cross-section to comprise a support 7 of paper, polymer film, etc., a thin, conductive, evaporable layer or film 8, and a lubricant layer or film 9; optionally a tough, hard, transparent film 10 may be positioned between the support 7 and the evaporable layer 8.
  • This intermediate film 10 preferably is of a layer of small hard particles in a suitable polymeric binder, for example, silica particles in a cellulose-acetate-butyrate (CAB) polymeric binder, or silica particles in a cross-linked polymer such as urethane cross-linked CAB, which may be light transmissive or transparent, to further reduce scratching of the material during electroerosion printing.
  • a suitable polymeric binder for example, silica particles in a cellulose-acetate-butyrate (CAB) polymeric binder, or silica particles in a cross-linked polymer such as urethane cross-linked CAB, which may be light transmissive or transparent, to further reduce scratching of the material during electroerosion printing.
  • the evaporable film 8 usually has a resistance from about 1 to 5 ohms per square centimeter and is frequently a vapor-deposited thin film of aluminum.
  • the resulting product can be used as a photomask or direct negative medium for the development of photosensitive materials, e.g., in the production of offset lithography masters, circuit boards, etc.
  • the recording material is preferably to be used as an offset master where the support is chosen to be an ink receptive material such as polyester. After imaging by electroerosion printing to expose the support layer selectively, the overlayer lubricating composition does not have to be removed, as illustrated by Fig. 2.
  • Electroerosion recording materials of the invention may be prepared in accordance with the following procedure: As a support, a flexible sheet of Mylar polyester 50 micrometers thick was provided. On this support, using conventional web-coating apparatus, a coating of silica particles in a urethane cross-linked CAB binder was put down. Onto this layer there was evaporation deposited, by conventional technique, a thin conductive film of aluminum, about 40 nm thick. This type of structure was used in the Examples hereinbelow, onto which the protective lubricating films were coated.
  • the DNP materials were coated with a 1% solid of the above mixture to a thickness of 2-10 microgram/square centimeter and dried at 80-110° C for about 0.5-1.0 minutes.
  • the top coated materials were then treated with 0.1-1.0% aqueous solution of potassium dichromate and dried at 100° C for 30 seconds.
  • the resulting materials were water insoluble but also had a water wettable surface which could be used as direct plate.
  • the corrosion resistance of the latter was increased 20-50 times compared with that of standard DNP.
  • the burnishing and scratching of the material is reduced by a factor of three to four over that of a film not treated with dichromate.
  • potassium dichromate solution is the preferred reagent for crosslinking of Gantrez S-95
  • inorganic reagents which are capable of doing the same.
  • aqueous solutions of aluminum salts aluminum acetate and nitrate were also tried successfully to crosslink the Gantrez and produce a water insoluble and water wettable surface.

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  • Manufacture Or Reproduction Of Printing Formes (AREA)
  • Lubricants (AREA)
  • Paints Or Removers (AREA)
  • Printing Plates And Materials Therefor (AREA)

Claims (12)

  1. Matériau d'enregistrement par électroérosion ayant une résistance à la corrosion améliorée comprenant :
    une couche support non conductrice flexible ;
    une couche conductrice mince sur ladite couche support, ladite couche conductrice pouvant être enlevée dans des zones choisies, par un procédé d'enregistrement par électroérosion ;
    une couche de conversion sur ladite couche conductrice, formée par la réaction d'un dichromate avec la couche conductrice ; et
    une couche supérieure composée d'un lubrifiant protecteur déposé sur la couche de conversion, ledit lubrifiant comprenant des particules de lubrifiant conductrices dispersées dans un liant polymère hydrophile insoluble dans l'eau partiellement réticulée.
  2. Matériau selon la revendication 1 dans lequel le liant polymère est un copolymère d'acide maléique et de méthyl-vinyl-éther.
  3. Matériau selon la revendication 2 dans lequel le copolymère est réticulé avec un dichromate.
  4. Matériau selon la revendication 3 dans lequel le composé de réticulation est du dichromate de potassium.
  5. Matériau selon la revendication 1 dans lequel les particules conductrices sont des particules de graphite.
  6. Matériau selon la revendication 1 dans lequel la couche support est un polymère hydrophobe tel que, après électroérosion de la couche conductrice, le matériau puisse être utilisé dans des applications d'offset direct.
  7. Matériau selon la revendication 1 comprenant en outre une couche dure mince de polymère réticulé située entre ladite couche support et ladite couche conductrice, ladite couche servant à accroître la résistance aux éraflures de ladite couche conductrice durant l'inscription par électroérosion.
  8. Matériau selon la revendication 7 dans lequel ladite couche dure mince est remplie de particules de silice.
  9. Matériau selon la revendication 1 dans lequel la densité de la couche supérieure est comprise entre deux microgrammes par centimètre carré à dix microgrammes par centimètre carré.
  10. Matériau selon la revendication 1 dans lequel la couche support non conductrice est en polyester et la couche conductrice est en aluminium.
  11. Matériau selon la revendication 1 comprenant en outre des particules de lubrifiant non conducteur dans la couche supérieure.
  12. Un procédé de préparation de matériau d'impression par électroérosion comprenant le dépôt d'une couche de revêtement lubrifiant sur une base substrat en polyester/film d'aluminium, ladite couche de revêtement étant un copolymère d'acide maléique et de méthyl-vinyl-éther, et en réticulant ladite couche de revêtement in situ avec un dichromate.
EP19890121803 1989-01-23 1989-11-25 Elément pour l'enregistrement par électro-érosion avec une résistance modifiée à la corrosion Expired - Lifetime EP0379673B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US30066589A 1989-01-23 1989-01-23
US300665 1994-09-02

Publications (3)

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EP0379673A2 EP0379673A2 (fr) 1990-08-01
EP0379673A3 EP0379673A3 (en) 1990-09-19
EP0379673B1 true EP0379673B1 (fr) 1994-04-13

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EP (1) EP0379673B1 (fr)
JP (1) JPH0761709B2 (fr)
DE (1) DE68914634T2 (fr)

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4339758A (en) * 1981-05-15 1982-07-13 Dennison Manufacturing Company Electrosensitive recording
US4622262A (en) * 1982-12-30 1986-11-11 International Business Machines Corporation Recording materials of improved lubricity for use in electroerosion printing
US4596733A (en) * 1983-12-30 1986-06-24 International Business Machines Corporation Electroerosion recording material with polyorganosiloxane overlayer
JPS60147389A (ja) * 1983-12-30 1985-08-03 インタ−ナショナル　ビジネス　マシ−ンズ　コ−ポレ−ション 放電記録材料
US4567490A (en) * 1983-12-30 1986-01-28 International Business Machines Corporation Electroerosion recording medium of improved lubricity
JPS60147337A (ja) * 1983-12-30 1985-08-03 インタ−ナショナル　ビジネス　マシ−ンズ　コ−ポレ−ション 放電破壊によつて直接陰画もしくは直接オフセツト・マスタを形成する方法
US4617579A (en) * 1984-04-05 1986-10-14 International Business Machines Corporation Hydrophilic protective coatings for electroerosion printing
US4550061A (en) * 1984-04-13 1985-10-29 International Business Machines Corporation Electroerosion printing media using depolymerizable polymer coatings

Also Published As

Publication number Publication date
DE68914634D1 (de) 1994-05-19
EP0379673A3 (en) 1990-09-19
DE68914634T2 (de) 1994-11-17
JPH02258344A (ja) 1990-10-19
EP0379673A2 (fr) 1990-08-01
JPH0761709B2 (ja) 1995-07-05

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