EP0147624A2 - Verfahren zur Herstellung von direkten Negativen und direkten Matrizen durch Elektroerosionsaufzeichnung - Google Patents

Verfahren zur Herstellung von direkten Negativen und direkten Matrizen durch Elektroerosionsaufzeichnung Download PDF

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Publication number
EP0147624A2
EP0147624A2 EP84114119A EP84114119A EP0147624A2 EP 0147624 A2 EP0147624 A2 EP 0147624A2 EP 84114119 A EP84114119 A EP 84114119A EP 84114119 A EP84114119 A EP 84114119A EP 0147624 A2 EP0147624 A2 EP 0147624A2
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EP
European Patent Office
Prior art keywords
direct
conductive
crosslinked
layer
overlayer
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EP84114119A
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English (en)
French (fr)
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EP0147624A3 (de
Inventor
Ali Afzali-Ardakani
Keith Samuel Pennington
Krishna Gandhi Sachdev
John Chen Shyan Shen
Mitchell Simmons Cohen
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International Business Machines Corp
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International Business Machines Corp
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Publication of EP0147624A2 publication Critical patent/EP0147624A2/de
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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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41C—PROCESSES FOR THE MANUFACTURE OR REPRODUCTION OF PRINTING SURFACES
    • B41C1/00—Forme preparation
    • B41C1/10—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme
    • B41C1/1008—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials
    • B41C1/1033—Forme preparation for lithographic printing; Master sheets for transferring a lithographic image to the forme by removal or destruction of lithographic material on the lithographic support, e.g. by laser or spark ablation; by the use of materials rendered soluble or insoluble by heat exposure, e.g. by heat produced from a light to heat transforming system; by on-the-press exposure or on-the-press development, e.g. by the fountain of photolithographic materials by laser or spark ablation

Definitions

  • the present invention relates to a method for making direct negatives and direct masters by electroerosion recording and products so formed.
  • Electroerosion printing is a well known technique for producing markings such as letters, numbers, symbols, patterns, such as circuit patterns or other legible or coated indicia, on a 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 locally removed during writing to provide such indicia on the recording material is usually a thin film of a conductive material which is vaporized in response to localized heating associated with sparking (arcing) initiated by applying an electric current to a stylus, multiple styli or electrodes (electrode and stylus are used interchangeably herein) in contact with the surface of the recording material comprising the thin conductive film on a non-conductive backing or support.
  • the thin conductive film is usually a thin vacuum-deposited film of a vaporizable metal, such as aluminum.
  • the electroerosion printing is effected by movement of the electrode (or a plurality of electrodes) relative to the surface of the electroerosion recording media while maintaining good electrical contact between the styli tips and the aluminum overlayer.
  • Electrical writing signals are fed to the electrode 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.
  • Electroerosion recording materials and processes are useful to directly produce human readable images, photomasks, etc.
  • Substrates of paper and various polymers have been employed with thicknesses on the order of 2 to 5 mils; as the erodible conductive layer, metal films such as vapor deposited aluminum films having a thickness 0 0 on the order of 100 A to 1,000 A have been utilized.
  • metal films such as vapor deposited aluminum films having a thickness 0 0 on the order of 100 A to 1,000 A have been utilized.
  • lubricants comprising long chain fatty acids, e.g., lauric, stearic and arachidic acids, and silicone oils.
  • long chain fatty acids e.g., lauric, stearic and arachidic acids, and silicone oils.
  • silicone oils e.g., silicone oils.
  • some eiec- trode scratching of the removable layer of the electroerosion recording material was observed. Accordingly, efforts continue to be directed to finding a superior lubricant and/or protective layer composition for the surface of electroerosion recording materials.
  • U.S. Patent 2,983,220 Dalton et al discloses a lithographic coating on an electroerosion recording sheet.
  • the coating may be a Zn0 or ZnS pigmented copolymer binder system.
  • a layer containing a conductive material, such as graphite, is disclosed in U.S. Patent 3,048,515 Dalton.
  • High temperature lubricants comprising graphite in oil are also known as is disclosed in U.S. Patent 3,242,075 Hunter.
  • U.S. Patent 3,514,325 discloses an electroerosion recording material in which a surface layer of crosslinked binder containing conductive particles such as zinc oxide is placed on top of the thin aluminum layer to achieve improved resistance to surface abrasion from a surface-contacting writing electrode.
  • a wide variety of resinous materials is suggested for the resin layer.
  • U.S. Patent 4,268,570 Imanaka et al, describes the optional use of a polyurethane adhesive layer between the polymer support and the aluminum layer, optionally having a top coating of an acrylic resin, a urethane acrylate resin, or a polyester block copolymer resin, in plastic molded products, such as, resin plates, tubes, and the like.
  • the structures are unrelated to electroerosion printing.
  • U.S. Patent 4,217,596, Jung describes an electroerosion recording paper comprising a layer of lacquer or printing ink or both between the thin conductive aluminum layer and a paper support.
  • U.S. Patent 4,305,082 Kusakawa et al, describes an electroerosion recording paper in which a resistance layer may be provided over a thin conductive aluminum film.
  • U.S. Patent 4,339,758 Bhatia et al describes an electrosensitive recording that uses a siliccn dioxide containing resinous base layer between a support and an overlying metallic film.
  • a lithographic plate must consist of two kinds of areas: printing areas, which accept grease (ink) and repel water, and non-printing areas, which accept water and repel grease (ink).
  • printing areas which accept grease (ink) and repel water
  • non-printing areas which accept water and repel grease (ink).
  • the electroerosion recording material comprises a thin, hard hydrophobic base layer between a transparent polymer support and an aluminum layer and a graphite-containing overlayer which is also hydrophobic.
  • the necessary hydrophilic/hydrophobic mapping is accomplished by removing the overlayer with a suitable solvent subsequent to electroerosion printing, whereby a substantial number of copies can be made before the aluminum layer starts to wear away.
  • a cross- linked protective overlayer which comprises a solid conductive lubricant, e.g., graphite in a crosslinked polymer matrix with or without a particulate material such as silica or alumina which serves as a scouring agent, thereby providing a scouring action to inhibit electrode fouling during the printing process.
  • a solid conductive lubricant e.g., graphite in a crosslinked polymer matrix with or without a particulate material such as silica or alumina which serves as a scouring agent
  • One object of the present invention is to provide a recording material suitable for generation of wear-resistant direct negatives and long run direct masters by electroerosion printing.
  • a further object of the present invention is to provide an electroerosion recording material with a durable crosslinked protective overlayer which can be employed to generate direct masters that permit a plurality of copies to be obtained without the same wearing off the recording material.
  • a further object of the present invention is to provide an improved electroerosion recording material which includes a crosslinked protective overlayer that resists abrasion and mechanical scraping.
  • Another object of the invention is to provide overlayer compositions which also exhibit improved contrast when used to produce direct negatives by electroerosion printing.
  • a dark polymer film e.g., a dark graphite/ crosslinked 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 conductive crosslinked overlayer with improved adhesion to a thin conductive film, e.g., aluminum.
  • a further object of the present invention is to provide direct negatives or direct masters as above described which further comprise a hard polymeric base layer.
  • An advantage of the overlayers of this invention is that they are electrically conductive and therefore can be used in thicker layers than can insulating films.
  • the optional hard base layer of the present invention formed thereon is represented by numeral 2 and is shown between the support 1 and the conductive film 3.
  • the protective overlayer of the present invention 4 is shown deposited thereon.
  • a direct negative is shown formed after electroerosion printing wherein -imaged regions 5 are shown where the conductive layer 3 and the protective overlayer 4 have been removed following electroerosion printing. Also shown are unwritten areas 6.
  • Fig. 3 shows an offset master formed per the present invention where unwritten area 6 as shown in Fig. 2 have been removed in a conventional manner, for example, by immersion in a solvent such as isopropanol, N-butanol, or conventional standard cleaning solutions for printing processes based on a water-dampering ink cycle.
  • a solvent such as isopropanol, N-butanol, or conventional standard cleaning solutions for printing processes based on a water-dampering ink cycle.
  • immersion is at room temperature and the abrasion resistant top coat is merely removed by swabbing the same.
  • Examples of the support which can be employed for the electroerosion recording material of the present invention are not unduly limited in any fashion so long as the base layer applied thereon will adhere thereto and the support is dimensionally stable and has sufficient thermal as well as mechanical stability to permit use under widely varying conditions.
  • the support of the present invention be a high optical quality polymer film, such as a transparent polyester film (Mylar ®).
  • a transparent polyester film Mylar ®
  • useful materials include paper, polymers such as polyethylene terephthalate, Riston, Kapton, polycarbonates, polypropylenes, polyethylenes, etc.
  • the desired product is a direct master an opaque support is acceptable, in this instance the printed area being receptive to oil based inks.
  • the support should be transparent (as should the hard base layer and fillers therin, when used).
  • the thickness of the support is not limited in any particular fashion so long as sufficient strength is provided to the direct negative or direct master during use. Typically, however, thicknesses will be on the order of about 1 mil to about 5 mils.
  • base layer of the present invention is optional, the use thereof provides a most highly preferred embodiment of the present invention.
  • the optional thin, hard polymeric base layer may or may not be crosslinked. It should have a sufficiently high tensile strength and a sufficiently high softening temperature so that it reduces plastic deformation of the support during electoerosion so that scratching of the conductive film is minimized.
  • hard supports e.g., polycarbonates
  • the base layer provides superior results when it is present.
  • the base layer contains an inorganic filler. Crosslinking the base layer is preferred since this generally provides a harder base layer, reducing the chance of generating a soft residue during electroerosion which might adhere to the electroerosion styli and inhibit writing.
  • crosslinking firmly fixes the filler in place, reducing the chance of filler dislodgement and adherence to the electroerosion styli.
  • a cross- linked base layer improves the corrosion resistance of the conductive film due to its good passivating properties, thus increasing shelf life and performance reliability.
  • the hard base layer is generally harder than Mylar®, preferably has a high Tg, for example, equal to or greater than 130°C, preferably has a hardness greater than 20 and more preferably greater than 30 (Knoops hardness), most preferably shows at least a 4 to 7% elongation at break (Tensile Instron) and when hydrophobic has a contact angle with water of equal to or greater than about 75°. If hydrophilic, it preferably has a contact angle with water of 30° or less.
  • the base layer is typically formed from solvent castable polymeric/oligomeric materials containing residual reactive sites such as free hydroxyl, epoxy, olefinic, acetylenic, ⁇ , p-unsaturated carbonyl moities, etc., which can most preferably be crosslinked by suitable reagents using heat and/ or radiation to accelerate the curing process. With these materials, crosslinking can also be accomplished by thermal or radiation-induced processes without the addition of another crosslinking agent.
  • Inorganic fillers such as Si0 2 , CaC0 3 , TiO 2 and calcium silicate, etc., generally of a particle size ranging from 0.5 ⁇ m to 10 ⁇ m can be incorporated by the usual techniques of grinding or milling together with the binder, a urethane solvent such as a methyl ethyl ketone (MEK)-toluene mixture, and a suitable dispersing agent such as Multron R221-75, a saturated polyester resin from Mobay Chemical Co.
  • a urethane solvent such as a methyl ethyl ketone (MEK)-toluene mixture
  • MEK methyl ethyl ketone
  • suitable dispersing agent such as Multron R221-75, a saturated polyester resin from Mobay Chemical Co.
  • Other useful solvents are the same as for overlayer formation later discussed.
  • the urethane forming reactions of the above described binders and urethane prepolymers are generally catalyzed by conventional organometallic reagents such as stannous oleate, stannous octoate, dibutyl-tin dioctoate, dibutyl-tin dilaurate, calcium or cobalt naphthenate, also tertiary amines, etc. Further acceleration of the crosslinking reaction can be achieved by thermal treatment of the coatings.
  • Crosslinked polymer coatings with beneficial properties can be obtained by the use of radiation curable acrylated polyurethane oligomers of the type "UVITHANE 783" and “UVITHANE 788" available from Thiokol Chemical Div.
  • Inorganic fillers such as silica can be dispersed by conventional techniques prior to coating.
  • Highly crosslinked films can also be obtained by thermal or radiation-induced copolymerization/ co-crosslinking of the above UV curable urethane oligomers with added multifunctional monomers such as pentaerythritol triacrylate (PETA) and trimethylol-propane triacrylate (TMPTA) available from Celanese Corporation.
  • PETA pentaerythritol triacrylate
  • TMPTA trimethylol-propane triacrylate
  • Desired crosslinked films with or without inorganic fillers can also be formed by thermal, microwave, or UV curing of coatings cast from blends of acrylated cellulosic derivatives and U V curable urethane oligomers described above.
  • Drying/curing is often at about 90 to about 110°C for about 5 to about 15 minutes. Higher and lower temperatures and times can be used.
  • base coat formulations were typically formed at an NCO:OH ratio of about 0.5 to about 1, more preferably 0.7 to 0.8.
  • the particulate solid filler when used, and this is a highly preferred embodiment of the invention, is typically used in an amount of from about 3 to about 40 weight percent, more preferably from 5 to 25 weight percent, based on the weight of total organics present.
  • Talysurf Traces of typical filled films show a peak to valley ratio on the order of 1 to 2 microns.
  • the base layer has a thickness of from about 2 to about 10 um.
  • a conductive layer typically of a metal such as aluminum, is formed on the base layer by a conventional technique such as sputtering or vacuum evaporation.
  • the only characteristic which the metal layer must exhibit is that upon application of an electrical pulse which results in an arc between the stylus and the metal layer, the same is cleanly eroded or vaporized with the protective layer thereover. If this criterion is met, any conductive material can be used in the present invention.
  • Useful metals include aluminum, magnesium, etc., typically formed by vacuum evaporation or sputtering in a conventional manner.
  • the metal layer exhibit a resistivity ranging from about 0.5 to 5 ohms per square centimeter.
  • the maximum conductivity is in no fashion limited.
  • the thickness of the conductive layer is not limited in any substantial fashion so long as it can be electroeroded. However, for optimum print quality at low voltage, typically the thickness 0 0 will be on the order of about 100 A to 1000 A.
  • the overlayer can be hydrophobic or hydrophilic. Its hydrophobic or hydrophilic nature is not important when it is used in a direct negative. If used in a direct negative, it may be totally removed prior to use or it may be permitted to remain in unwritten areas. If hydrophobic, it should be removed if it is to be used in a direct master in a printing process involving oleophilic inks. As one skilled in the art will appreciate, the support or base layer, whichever is exposed following electroerosion, should have a wettability opposite the overlayer if the overlayer remains, if use as a direct master is contemplated, to ensure selective wetting and non- wetting by the inks use, specifically that written areas preferentially receive the ink.
  • conventional oleophilic or aqueous inks are used in a conventional manner. It is generally preferred to remove the unwritten areas of the protective overlayer, be it hydrophobic or hydrophilic, to avoid any possible smudging problem during use as a direct master. It will be appreciated by those skilled in the art that instead of the conventional oil-based ink, this technology is capable of being used with an aqueous ink provided that the electroerosion process and the nature of the overcoat and base layers are differently chosen so that the ink-receptive areas where printing is desired are hydrophilic, and the background areas where no ink is desired are hydrophobic.
  • the overlayer should D e resistant to humidity to ensure a good shelf life, ease of shipping and ease of handling. If used in a direct master, it should, of course, be resistant to any materials used, e.g., water, oleophilic ink, etc., if it is not removed.
  • the most critical aspect of the overlayer of the present invention is that it be crosslinked so that the same will not come off the thin conductive layer during handling, etc., but the same can be removed in unwritten areas following electroerosion, if desired, by a simple procedure, such as solvent contact and swabbing.
  • a hydrophilic overlayer of the present invention should be resistant to the water cycle on a press during printing. It most desirably exhibits a contact angle with water of about 30° or less. As one skilled in the art will appreciate, oleophilic ink should not wet the hydrophilic overlayer. Further, it should be water insoluble but water wettable.
  • a hydrophobic overlayer per the present invention illustrates a contact angle with water of 75° or more.
  • the exact polymer selected for use in the present invention is not overly critical so long as it can be crosslinked to form a tough polymeric layer.
  • a most desirable characteristic for the binder system is that it should form a stable dispersion with particulate materials such as graphite, ZnO, silica, alumina, etc.
  • the polymer be cross- linked to a degree of from about 10 to about 50% (the percentage of the crosslinking sites on the hydrophilic binder which are crosslinked).
  • the degree of hydrophilicity of crosslinked hydrophilic polymer-particulate films used as the overlayer in the present invention should be such that the non-image areas of the print material with hydrophobic written regions have the ink- repelling property necessary for a direct master when using oleophilic inks in a conventional water-ink cycle on a printing press.
  • the factors which dictate our selection of materials and processes for generation of the at least partially crosslinked hydrophilic polymer layer include:
  • Hydrophilic polymers which can be crosslinked per the present invention include but are not limited to polyvinyl alcohol, polyacrylic acid, polyethylene glycol, polypropylene glycol, polyfunctional polyols, N,N,N',N'-tetrakis (2-hydroxypropyl)ethylenediamine and polycaprolactone polyol.
  • Hydrophobic polymers include polyether or polyester polyols, block copolymers of ethylene and propylene oxides on a propylene glycol base, the block copolymers being useful as components in any proportion so long as the resulting block copolymer is hydrophobic.
  • the preferred materials should have two or more reactive hydroxy sites per chain for reaction with the crosslinking agent.
  • molecular weight of such materials is not overly important since they will be at least partially crosslinked; however, prior to crosslinking, typically they will exhibit a molecular weight on the order of about 100 to about 2,000 (all molecular weights herein are number average molecular weight).
  • Crosslinking can be by any conventional means to crosslink the particular polymer involved, e.g., by chemical crosslinking, by thermal crosslinking, by high energy particle crosslinking, combinations thereof, or the like.
  • the isocyanate compounds used in the binder typically have a molecular weight of 150-500 per NCO group.
  • the polyisocyanates have at least three reactive sites, i.e., NCO groups, per chain so that crosslinking and thermosetting properties are established in the resulting binder.
  • the cross linking reaction can be accelerated using conventional catalysts as are known in the art.
  • Useful catalysts are disclosed in European Application 113005.
  • Catalyst concentrations of about 0.1 to about 1.5 percent by weight based on total organics are usually satisfactory.
  • Further acceleration can be achieved by thermal treatment.
  • Desired crosslinked films can also be formed by thermal, microwave, or UV curing of coatings cast from blends of hydrophilic polymers and UV curable crosslinking agents.
  • a crosslinker such as a polyisocyanate, etc.
  • Some hydrophilic or hydrophobic sites should remain after crosslinking, of course.
  • the NCO:OE ratio can be varied from 0.1 to 0.5 and dry overlayer density between about 1.0 to about 20 micrograms/cm 2 .
  • the conductive solid lubricant to binder ratio can vary from about 80:20 to about 50:50 by weight, the scouring agent can range from about 2 to about 10% of the weight of the solid conductive lubricant, and the catalyst concentration preferably ranges between 0.5-1.5 wt.% based on binder and crosslinker weight for crosslinking during the curing.
  • Drying/curing is usually at about 100°C ⁇ 15°C for about 1 to about 10 minutes. Higher and lower temperatures and times can be used, if desired.
  • crosslinking is typically at an elevated temperature of about 100°C, sufficient crosslinking being easily effected in a time of from about 5 minutes to about 10 minutes in air at these conditions to provide tack-free, hard, adherent and abrasion- resistant films.
  • the use of a catalyst reduces the curing temperature and curing time. Minimum curing temperature and shortened cure time are desirable to limit any adverse effects on the substrate, such as, distortion of a polymer substrate, e.g., Mylar @.
  • volatile non-reactive solvents can be used in the production of the compositions of the invention to reduce the solids content and permit the coating of very thin overlayers.
  • Classes of suitable solvents include, but are not limited to, aromatic solvents, such as, toluene and xylene; ketones, such as, methyl ethyl ketone and isophorone; acetates, such as ethyl acetate and butyl acetate; and alcohols such as isopropyl alcohol.
  • the preferred solvents employed in the overlayer composition are isopropanol, tetrahydrofuran or a mixed solvent such as 80 parts by weight of methyl ethyl ketone and 20 parts by weight of toluene or THF-toluene mixtures. While not to be construed as limitative, we have found that an amount of solvent sufficient to provide 5 to 10 wt % total solids (lubricant, binder, and crosslinker), balance solvent, are quite acceptable.
  • the overcoat layer should have a dry density between about 1.0 and about 20 micro- grams/cm 2 , since lower thicknesses give inadequate lubrication and higher thicknesses are detrimental to 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. Also the lubricating agent-binder ratio should be adjusted to avoid flake off of the lubricating agent and the scouring agent when employed.
  • the conductive solid lubricant is not limited per the present invention so long as it is a conductive particulate solid.
  • laminar solids may be employed as such conducting agents.
  • Examples of such solids are graphite, carbon black, MoS 2 , WS 2 , TaS 2 and graphite.
  • Other compounds may be considered such as ZnO, T10 2 and CaF 2 since they have all been shown to be lubricants and conductive.
  • soft metal particles such as Sn, Cu, Zn, Ag, Pb, Au, Bi and Al are expected to be useful in the invention. Work has been carried out with MoS 2 , Al, and Zn, but graphite was found to be most satisfactory in terms of its effectiveness as a conductive lubricant and dispersability and coating quality.
  • ELECTRO-DAG 154 comprises graphite dispersed in a cellulose derivative such as ethyl cellulose and isopropanol as a solvent (about 20 wt % solids, 20 wt % of which is binder and 80 wt % of which is graphite), balance solvent. After the coating is applied, only a short drying cycle (about 3 minutes at 100°C) is needed to drive off the solvent. Colloidal Suspension No.
  • Graphite 150 from Superior Graphite Co. contains purified carbon/ graphite of an average particle size less than one micron in water while No. 211 is a similar suspension in trichloroethane.
  • Dag 191 is an aqueous dispersion of graphite in a hydrophilic binder which has 15% total solids of which 90% is graphite and the balance is binder and surfactant.
  • binder concentrations can be effectively used, e.g., from about 10% binder to 90% conductive agent/scouring agent, to from about 60% binder to 40% conductive agent/scouring agent.
  • the change in binder concentration changes the electrical conductivity of the overlayer.
  • Optimum concentration of organic components in the crosslinked overlayer that has been found to be most satisfactory to provide the desired resistance to smudging and flake off during handling, wear resistance and print quality has been found to be 25-35% by weight, although binder contents of 20-50% by weight have total solids in layer, based on total solids in the layer, also been employed without adversely affecting print quality.
  • Size is not overly limited, but normally the particulate conductive agent will have a size of from about 0.1 to about 2.5 microns.
  • graphite When graphite is used as the conductive agent, it most preferably has a size of less than 1 micron.
  • the solid conductive lubricant such as graphite in these overlayers imparts lubricity, increased contrast between written and unwritten areas, electrical conductivity and helps suppress electrode fouling, while the crosslinked polymer provides a coherent, wear-resistant matrix.
  • the optional scouring agent further provides protection against fouling.
  • Such an overlayer when hydrophilic and water-resistant, provides an ink- repelling background similar to aluminum in terms of wetting characteristics but is superior in terms of wear life on the press during the printing operation. Typically, this overlayer will be on the order of about 2.0 to 35 micrograms per square centemeter in dry density, and long press life for the direct master will be insured.
  • the purpose of the scouring agent which is also a particulate solid, is basically to remove organic/inorganic residue which might adhere to the electrodes during electroerosion recording.
  • the scouring agent will be a hard particulate material, for example, a material exhibiting a MOH's hardness of at least about 6, though preferably no greater than about 9 such as silica, alumina, titania, ZnO, etc.
  • the scouring agent can be relatively freely selected from materials which do not degrade the at least partially crosslinked polymer or interact with the particulate conductive solid.
  • Useful materials can be selected from metal oxides of Group III and Group IV elements (see the Chemical and Physics Handbook, CRC Press, ed. by Robert C. Weast).
  • the particle size thereof is not particularly limited so long as the desired scouring function is exhibited, but most preferably, with electroerosion electrodes as are currently in use, the particle size of the scouring particles will be on the order of from about 0.1 to about 3 microns.
  • the layers are formed using conventional techniques as earlier discussed.
  • the overlayer comprising a conductive lubricant solid and the crosslinked polymer is typically formed by blending the non-crosslinked polymer, the conductive lubricant and the optional scouring particles in an appropriate solvent using a conventional ball milling technique. The resulting homogenous dispersion is thoroughly mixed with a crosslinking agent followed by appropriate dilution and application on the metallized substrate.
  • the overlayer is at least partially cured at the desired conditions as earlier described.
  • Fabrication of a typical structure consisted of a transparent polyester substrate, specifically a 50 ⁇ m thick Mylar @ sheet on which a 5-7 ⁇ m thick hard underlayer comprised of a silica pigmented urethane crosslinked cellulosic binder had been coated and dried/cured, as disclosed in Example 1 of EP-A-113005.
  • a protective overlayer comprised of graphite and a hydrophilic polymer matrix which is to be crosslinked per the present invention was formed as described below.
  • the dispersion Prior to coating application, the dispersion was combined with 0.5 part of a polyisocyanate (Desmodur N-75 from Mobay Chemical Co.) dissolved in 5 parts of a 3:2 volume mixture of THF-toluene, mixed thoroughly and applied on the aluminum layer using a conventional web coating apparatus followed by drying/curing at about 100°C for 5-10 minutes to obtain a dry coating thickness of 10 to 15 micrograms per cm 2 .
  • the overcoat was removed prior to use as a direct master with an oleophilic inks.
  • EXAMPLE 1 The procedure of EXAMPLE 1 was followed except that a modified overlayer was formed by including 0.5 part of zinc oxide (New Jersey Zinc Co.) among the ingredients recited in EXAMPLE 1 before ball milling.
  • the final coating formulation containing the polyisocyanate crosslinking agent was prepared following the procedure of EXAMPLE 1 and applied onto the aluminum surface to form a protective layer having a dry density of 10 to 20 micrograms per cm 2 .
  • Teracol 1,000 of EXAMPLE 1 and 2 are Teracol 2,000, polycaprolactone glycol, polyethylene adipate glycol, polypropylene ether glycol and similar polyols.
  • the mixture was ball milled to form a uniform dispersion to which was added a solution of a polyisocyanate crosslinking agent (Desmodur N-75; 0.5 part in 5.0 parts of MEK-toluene mixture, 3:2 by volume), 0.01 part of T-9 catalyst (stannous octoate; M T Co.) and 0.02 part FC-430 (3M Co.).
  • a polyisocyanate crosslinking agent (Desmodur N-75; 0.5 part in 5.0 parts of MEK-toluene mixture, 3:2 by volume)
  • T-9 catalyst stannous octoate; M T Co.
  • FC-430 0.02 part FC-430 (3M Co.).
  • overcoat composition described in EXAMPLE 3 was modified by adding ZnO, Ti0 2 or silica particulate material prior to ball milling. Subsequent processing and application following the procedure of EXAMPLE 3 provides overlayers which exhibit further protection against fouling during electroerosion printing.
  • the mixture was ball milled for 16 hours, combined with methylol melamine (0.2 parts) and the pH was adjusted to 5-5.5 in a conventional manner.
  • the formulation was thoroughly mixed and applied on the aluminized substrate and dried/cured all as per EXAMPLE 1 to provide the desired water- based protective overlayer.
  • Other molecular weight polyvinyl alcohols can be used, of course, e.g., of a molecular weight of 20,000-50,000.
  • Processing per EXAMPLE 3 provided a cross-linked hydrophobic overlayer having a dry coating thickness of 0.4 to 0.6 microns.
  • a conventional cleaning solution or with isopropanol, trichloroethane or MEK by swabbing.
  • the protective overlayer was formed from the following composition. All parts and percents are by weight.
  • the resulting protective overlayer had a contact angle with water of ca. 30° and was highly adherent to the conductive film.
  • the material thus formed When employed as printing material using an electroerosion device at 30-60 volts the material thus formed may be imaged by clean erosion of aluminum which is accompanied by the removal of the overlayer in the written or imaged areas thereby exposing the base coat when used with consequent generation of the scratch-free direct negative and direct offset master since the overlayer in the unwritten areas is non-receptive to oil based or aqueous inks, depending on if it is hydrophobic or hydrophilic inks.
  • the written area may remain ink receptive while the unwritten area may be non-receptive to oil based inks depending upon the composition of the oil-based ink used.

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  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Thermal Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Printing Plates And Materials Therefor (AREA)
  • Electronic Switches (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Drawing Aids And Blackboards (AREA)
EP84114119A 1983-12-30 1984-11-23 Verfahren zur Herstellung von direkten Negativen und direkten Matrizen durch Elektroerosionsaufzeichnung Withdrawn EP0147624A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US56693283A 1983-12-30 1983-12-30
US566932 1983-12-30

Publications (2)

Publication Number Publication Date
EP0147624A2 true EP0147624A2 (de) 1985-07-10
EP0147624A3 EP0147624A3 (de) 1987-02-25

Family

ID=24265032

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84114119A Withdrawn EP0147624A3 (de) 1983-12-30 1984-11-23 Verfahren zur Herstellung von direkten Negativen und direkten Matrizen durch Elektroerosionsaufzeichnung

Country Status (3)

Country Link
EP (1) EP0147624A3 (de)
JP (1) JPS60147337A (de)
CA (1) CA1221832A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0379673A3 (en) * 1989-01-23 1990-09-19 International Business Machines Corporation Electroerosion recording medium of improved corrosion resistance
WO1991008108A1 (en) * 1989-11-28 1991-06-13 Presstek, Inc. Lithography plates and method and means for imaging them
US5084331A (en) * 1989-01-23 1992-01-28 International Business Machines Corporation Electroerosion recording medium of improved corrosion resistance
EP0501065A1 (de) * 1991-02-25 1992-09-02 Presstek, Inc. Lithographische Druckplatten, die bildunterstützende Pigmente enthalten
US5176947A (en) * 1990-12-07 1993-01-05 International Business Machines Corporation Electroerosion printing plates
EP0849090A3 (de) * 1996-12-19 1998-07-01 Agfa-Gevaert N.V. Thermo-empfindliches Aufzeichnungselement zur Herstellung lithographischer Druckplatten mit verbesserten transportierenden Eigenschaften
EP0830552A4 (de) * 1995-06-02 2000-02-09 Napp Systems Inc Verfahren zur verminderung des niveaus eines verdunnungsmittels in verdunnungsmittelenthaltenden harzen mittels mikrowellenenergie

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3514325A (en) * 1966-11-17 1970-05-26 Hewlett Packard Co Electrosensitive recording article and method of making the same
GB1480081A (en) * 1973-09-18 1977-07-20 Ricoh Kk Methods of producing printing masters by spark-recording
GB1490732A (en) * 1974-04-05 1977-11-02 Vickers Ltd Electro-responsive printing blanks and their inscription
JPS59124889A (ja) * 1982-12-30 1984-07-19 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
JPS59124888A (ja) * 1982-12-30 1984-07-19 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

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5165345A (en) * 1988-08-19 1992-11-24 Presstek, Inc. Lithographic printing plates containing image-support pigments and methods of printing therewith
EP0379673A3 (en) * 1989-01-23 1990-09-19 International Business Machines Corporation Electroerosion recording medium of improved corrosion resistance
US5084331A (en) * 1989-01-23 1992-01-28 International Business Machines Corporation Electroerosion recording medium of improved corrosion resistance
WO1991008108A1 (en) * 1989-11-28 1991-06-13 Presstek, Inc. Lithography plates and method and means for imaging them
US5176947A (en) * 1990-12-07 1993-01-05 International Business Machines Corporation Electroerosion printing plates
EP0501065A1 (de) * 1991-02-25 1992-09-02 Presstek, Inc. Lithographische Druckplatten, die bildunterstützende Pigmente enthalten
EP0830552A4 (de) * 1995-06-02 2000-02-09 Napp Systems Inc Verfahren zur verminderung des niveaus eines verdunnungsmittels in verdunnungsmittelenthaltenden harzen mittels mikrowellenenergie
EP0849090A3 (de) * 1996-12-19 1998-07-01 Agfa-Gevaert N.V. Thermo-empfindliches Aufzeichnungselement zur Herstellung lithographischer Druckplatten mit verbesserten transportierenden Eigenschaften

Also Published As

Publication number Publication date
JPS60147337A (ja) 1985-08-03
EP0147624A3 (de) 1987-02-25
CA1221832A (en) 1987-05-19

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