WO2006111451A1

WO2006111451A1 - Process for contact printing of pattern of electroless deposition catalyst.

Info

Publication number: WO2006111451A1
Application number: PCT/EP2006/061055
Authority: WO
Inventors: Luc Leenders; Michel Werts
Original assignee: Agfa-Gevaert
Priority date: 2005-04-20
Filing date: 2006-03-27
Publication date: 2006-10-26
Also published as: IL186691A0; KR20080011206A; EP1877263A1; JP2008538335A

Abstract

A process comprising the step of : contact printing exclusive of stamp printing a pattern of an electroless deposition catalyst via a hydrophilic phase to a receiving medium, wherein said electroless deposition catalyst requires no activation prior to electroless deposition.

Description

PROCESS FOR CONTACT PRINTING OF PATTERN OF ELECTROLESS DEPOSITION CATALYST

Field of the invention

The present invention relates to a process for the contact printing of patterns of electroless deposition catalyst via a hydrophilic phase.

Background of the invention.

In addition to the printing of conventional colored inks, printing is being used more and more for the application of patterns of functional materials. In the case of functional materials which are only soluble or dispersible in aqueous media, problems may arise in incorporating them into oleophilic inks.

WO 01/88958 discloses in claim 1 a method of forming a pattern of a functional material on a substrate comprising: applying a first pattern of a first material to said substrate; and applying a second functional material to said substrate and said first material, wherein said first material, said second functional material, and said substrate interact to spontaneously form a second pattern of said second functional material on said substrate, to thereby form a pattern of a functional material on a substrate. WO 01/88958 further discloses in claim 27 a method of forming a pattern of a functional material on a substrate comprising: non- contact printing a first pattern of a first material on said substrate; and applying a second functional material to said substrate and said first material, wherein said first material, said second material, and said substrate interact to spontaneously form a second pattern of said second functional material on said substrate, to thereby form a pattern of a functional material on a substrate.

WO 01/88958 also discloses in claim 47 a method of forming a pattern of a functional material on a substrate comprising: non- contact printing a first pattern of a first material on said substrate; and applying a second functional material to said substrate and said first material, wherein said first and second functional materials are selected to have a sufficient difference in at least one property of hydrophobicity and hydrophilicity relative to one another such that said first material, said second functional material, and said substrate interact to spontaneously form a second pattern of said second functional material on said substrate, to thereby form on said substrate a second pattern of said second functional material, wherein said second pattern is the inverse of said first pattern, to thereby form a pattern of a functional material on a substrate.

WO 01/88958 also discloses in claim 57 a method of forming an 5 electrical circuit element, comprising: applying a first pattern of a first material on a substrate; and applying a second material to said substrate and said first material, wherein said first material, said second material, and said substrate interact to spontaneously form a second pattern of said second material on said substrate,

W thereby forming an electrical circuit element.

WO 01/88958 also discloses in claim 110 an electrical circuit element comprising: a substrate; a first pattern of an insulating material applied to said substrate; and a second pattern of an electrically conducting material applied to said substrate and said

15 first material, wherein said insulating material, said electrically conducting material, and said substrate interact to spontaneously form a second pattern of said electrically conducting material on said substrate when said electrically conducting material is applied to said substrate having said first pattern of said insulating

20 material applied thereon.

WO 01/88958 also discloses in claim 123 an electronic device comprising: a) a first element comprising i) a first substrate; ii) a first pattern of an insulating material applied to said substrate and iii) a second pattern of an electrically conducting material

25 applied to said substrate and said first material, wherein said insulating material, electrically conducting material, and said substrate interact to spontaneously form a second pattern of said electrically conducting material on said substrate when said electrically conducting material is applied to said substrate having

30 said first pattern of said insulating material applied thereon; b) a second circuit element comprising i) a second substrate; ii) a third pattern of an insulating material applied to said second substrate and iii) a fourth pattern of an electrically conducting material applied to said second substrate and said third material, wherein

35 said insulating, electrically conducting material, and said second substrate interact to spontaneously form a fourth pattern of said electrically conducting material on said substrate when said electrically conducting material is applied to said substrate having said third pattern of said insulating material applied thereon; and

40 c) an electrically connection between said first and second circuit elements .

WO 01/88958 also discloses in claim 127 a Radio Frequency (RF) tag comprising a pattern of a non-conductive first material on a substrate and a coating of an electrically conductive second material disposed over said substrate and said first material, wherein said first material, said second material, and said substrate interact to spontaneously form a second pattern of said 5 second material on said substrate, to thereby form an Inductor- Capacitor (LC) resonator on said substrate.

WO 01/88958 also discloses in claim 141 a mechanical device comprising: a) a first component comprising: i) a first substrate; ii) a first pattern of first material to said first substrate and

10 iii) a second pattern of material applied to said first substrate and said first material, wherein said second pattern of said second material is spontaneously formed by the interaction of said first material, said second material and said first substrate; and b) a second component comprising i) a second substrate; ii) a third

15 pattern of a third material applied to said second substrate and iii) a fourth pattern of a fourth material applied to said second substrate and said third material, wherein said fourth pattern of said fourth material is spontaneously formed by the interaction of said third material, said fourth material and said substrate; and

20 wherein said first and second components are oriented in a such a way that the second and fourth patterns oppose each other, and are selected from the group consisting of identical patterns, inverse patterns, and any mechanically useful combinations.

A number of different techniques can be used for printing.

25 These techniques can be separated into so-called non-impact printing techniques and so-called contact printing techniques, which include screen printing, gravure printing, flexographic printing and offset printing. The particular printing technique selected for a particular job will depend on the application, substrate and desired

30 print volume. For the printing of high volumes at low cost, for example for the printing of packages, fast printing techniques are required such as gravure printing, flexographic printing or offset printing. The low cost is due to the high printing speeds of approximately 500 m/min or more for flexographic printing and up to

35 900 m/min or more for heat set/web-offset printing. This makes offset printing particularly suitable for the cheap production of printed matter. Offset printing and gravure printing provide the highest quality prints with resolutions down to 10 μm.

In 2001, Hohnholz et al . in Synthetic Metals, volume 121, pages

40 1327-1328, reported a novel method for the preparation of patterns from conducting and non-conducting polymers on plastic/paper substrates. This method, "Line Patterning" (LP), does not involve printing of the polymers and incorporates mostly standard office equipment, e.g. an office type laser printer. It is rapid and inexpensive. The production of electronic components, e.g. a liquid crystal and a push-button assembly were reported.

Offset (lithographic) printing presses use a so-called printing master such as a printing plate which is mounted on a cylinder of the printing press. In conventional offset printing, the master carries a lithographic image on its surface, which consists of oleophilic (or hydrophobic, i.e. ink-accepting, water-repelling) areas as well as hydrophilic (or oleophobic, i.e. water-accepting, ink-repelling) areas. A print is obtained by first applying a fountain medium (also called dampening liquid) and then the ink to lithographic image on the surface of the printing plate on a drum, both are then transferred to an intermediate (rubber) roll, known as the offset blanket, from which they are further transferred onto the final substrate. The fountain medium is first transferred via a series of rolls to the printing plate. It conventionally acts as a weak sacrificial layer and prevents ink from depositing on the non- image area of the plate and has the function of rebuilding the nonprinting (desensitized) areas of the printing plate during a press run. This is usually realized with an aqueous solution of acid, usually phosphoric acid, and gum arabic, the gum is adsorbed to the metal of the plate and thereby making a hydrophilic surface. The dampened plate then contacts an inking roller and only accepts the oleophilic ink in the oleophilic image areas. Fountain media have historically contained isopropyl alcohol to reduce the surface tension and thereby to provide for more uniform dampening of the printing plate, but, by eliminating (or greatly reducing) the isopropyl alcohol as a fountain medium additive, printers are able to reduce VOC (volatile organic compound) emissions significantly. In such fountain media isopropyl alcohol is replaced with lower volatility glycols, glycol ethers, or surfactant formulations. Conventional fountain media may also contain anti-corrosion agents, pH-regulators and surfactants .

EP-A 1 415 826 discloses a process for the offset printing of a receiving medium with a functional pattern comprising in any order the steps of: applying a printing ink to a printing plate and wetting said printing plate with an aqueous fountain medium containing a solution or a dispersion containing at least one moiety having at least colouring, pH-indicating, whitening, fluorescent, phosphorescent, X-ray phosphor or conductive properties.

In addition to conventional offset printing, several alternative methods have been developed, such as reverse lithography, driography and single fluid offset printing. In reverse lithography, a water- or glycol-based hydrophilic colored ink is used in combination with an oleophilic fountain medium. The printing plate contains image areas which preferentially attract a hydrophilic liquid and non-image areas which are repellent to the hydrophilic liquids. Printing plates can be prepared by applying a pattern of a material with a good tolerance to aqueous (miscible) liquids such as a vinylacetate- ethylene copolymer resin, polyester resin or a composition containing shellac, polyethylene glycol and wax onto a hydrophobic base sheet, such as polystyrene or polyethylene coated Mylar. Alternatively, the printing plate can be prepared by applying a hydrophilic liquid-repelling thermosetting siloxane composition as the non-image pattern on a zinc base material (US 3,356,030) . Additives like carbon black or zinc oxide may be added to the resin to increase the surface roughness, thereby improving the ink uptake. The hydrophilic inks can be dye- or pigment-based and contain a binder and water and/or ethylene glycol as the main vehicle. The (hydrophobic) fountain medium is based on hydrocarbons such as Textile Spirits or Super Naphtholite, mineral oils or silicon oils. Waterless or driographic offset printing was developed, for example by Toray Industries of Japan, to reduce the emission of VOCs from the fountain medium in conventional offset printing by dispensing with a fountain medium and only using an oleophilic ink. The non-image areas of a driographic printing plate are coated with an ink-repellant polymer, such as a silicone, while the image areas are ink-accepting surfaces for example a grained aluminium base plate, optionally overcoated with an additional coating layer. During driographic printing, only ink is supplied to the master.

However, these driographic printing processes still have the disadvantage of VOC emission from the oleophilic ink. This has resulted in the development of water-based driographic inks, which contain surfactants, rewetting agents, dyes and/or pigments and resins in addition to water. Such driographic printing plates can be used, with, for example, the grained aluminium surface of the printing plate as the image areas and any type of hydrophobic material that repels the ink for the non-image area.

Conventional and reverse offset printing require the continuous monitoring and adjusting of the ink/ fountain balance so that the ink adheres exclusively to the printing areas of the plate to ensure the production of sharp, well-defined prints. Single-fluid inks have been developed to eliminate the need for the operator continuously to monitor and adjust the ink/fountain balance. These inks consist of a fine emulsion of the ink in the fountain or of a fine emulsion of the fountain in the ink and are applied to the printing plate via the ink rollers. The fountain is oleophilic when the ink is hydrophilic and is hydrophilic when the ink is oleophilic e.g. with the oleophilic ink part based on vinyl- and hydrocarbon resins with dyes and/or pigments and the hydrophilic fountain part based on glycol/water mixtures.

Reverse offset printing inks using a hydrocarbon or mineral oil as fountain medium are described, for example, in US 3,532,532, US 3,797,388, GB 1,343,784A and US 3,356,030. None of these patents disclose the addition of functional materials, other than dyes and/or pigments, to the hydrophilic ink or to the hydrophobic fountain medium.

Water-based driographic offset inks are, for example, described in WO 99/27022A, WO 03/057789A and DE 4119348A. None of these patents discloses the addition to the hydrophilic ink of functional materials, other than dyes and/or pigments.

Single fluid inks for offset printing are, for example, disclosed in US 4,981,517 and in WO 00/032705A, but neither discloses an ink containing functional materials in the hydrophilic (fountain) part of the ink emulsion.

US 2005/0003101A discloses a method of preparing a substrate such that it is capable of sponsoring autocatalytic plating of metal patterns over a pre-determined area of its surface comprising the steps of: i) coating some or all of the substrate material by a pattern transfer mechanism with a first layer composed of a first layer material comprising a catalytic material; ii) coating the first layer by a pattern transfer mechanism with a second layer composed of a second layer material such that the second layer overlaps the first layer to form a seal, the second layer material being incapable of promoting and/or sustaining the desired catalytic reaction iii) using an energetic ablative scribing process to remove a pre-determined pattern of material from the second layer material in order to expose the first layer material . The catalytic material is applied via a pattern transfer mechanism, such as inkjet printing or screen printing, coating a second layer over the first layer to form a seal and using an energetic ablative scribing process to remove a pre-determined pattern of the second layer in order to expose the first layer. Metal is deposited on the first catalytic layer by electroless plating. The disadvantage of this process is that the described scribing processes, such as e-beam, focused UV beam, collimated X-ray beam or plasma beams are slow processes.

DE 2757029A discloses a process for the manufacture of integrated circuits in which an ink enriched with palladium, copper or silver nuclei is printed on a substrate provided with an adhesion-providing layer, the conductive patterns thereby produced then being metallized chemically in a copper depositing bath to electrically conductive circuits. Neither the printing method nor 5 the ink compositions are further specified.

WO 92/21790A discloses a method comprising printing a catalytic ink in a two-dimensional image on a moving web from a rotating gravure roll; wherein said catalytic ink comprises a solution of less than 10% by weight solids comprising polymer and a Group IB or

W Group 8 metal compound, complex or colloid; wherein said ink has a viscosity between 20 and 600 centipoises as measured with a Brookfield No. 1 spindle at 100 rpm and 25°C; and wherein said image is adaptable to electroless deposition of metal. This method has the disadvantage of the image not being directly usable for

/5 catalyzing electroless deposition. Moreover, rotogravure printing suffers from the disadvantages of the high cost of a gravure roll compared to an offset printing plate.

WO 93/04215A discloses an aqueous, catalyst emulsion adapted for forming crosslinked, polymeric coatings which can catalyze the

20 electroless deposition of metal, said emulsion comprising (a) water, (b) surfactant-stabilized particles of a crosslinkable, water- insoluble polymer dispersed as an emulsion in said water, (c) a water soluble compound of a Group 8 metal, and (d) a crosslinking agent. This method has the disadvantage of the coating not being

25 directly usable for catalyzing electroless deposition.

US 6,521,285 discloses a method for electroless deposition of conductive material (8) on a substrate (5) , using a stamp (1) having a surface onto which an ink is applied, preconditioning said substrate (5) by providing a seed layer (6) having enhanced affinity

30 between said ink and said preconditioned substrate, and bringing said surface of said stamp (1) into contact with said preconditioned substrate (5), comprising the steps of: treating said surface of said stamp (1) to render said surface wettable by said ink, pressing said surface of said stamp (1) covered with said ink being a

35 catalyst (4) in molecular form and being polar onto said substrate (5), thereupon separating said stamp (1) from said substrate (5) by leaving at least part of a layer (7) of said catalyst onto said substrate (5) and electroless plating said substrate (5) in areas of said surface being covered with said layer of catalyst (7) with said 0 conductive material (8). Applying a catalyst for electroless plating from an aqueous solution using a stamp having a patterned surface, as disclosed in US 6,521,285, is an alternative method of application. However, this method is not roll-to-roll and is very slow compared to offset printing.

US 5,300,140 discloses a hydroprimer for the deposition of firmly adhering metal coatings onto substrate surfaces by application of a thin layer of the hydroprimer to the substrate surface, if appropriate sensitisation and subsequent currentless wet-chemical metallisation, wherein the hydroprimer contains, as the essential constituents, a) a water-dispersible polymer selected from the group consisting of water-dispersible polyacrylates, polybutadienes, polyesters, melamine resins, polyurethanes, and polyurethane-ureas, b) as metallisation catalyst an ionic noble metal, a colloidal noble metal or both or a covalent or complex compound of a noble metal with organic ligands, c) a filler selected from the group consisting of organic and inorganic fillers, in an amount of 5 to 35% by weight, and d) water. Furthermore, US 5,300,140 discloses that the hydroprimer can be applied to the surfaces of the plastic by the customary methods, such as printing, stamping, dipping, brushing, knife-coating, painting on and rolling on and spraying. US 4,253,875 discloses a catalytic lacquer for the production of printed circuit boards using basic materials and metal deposition methods having a composition of: (a) a binding agent comprising water soluble or dispersable compounds selected from the group consisting of acrylic resins, phenolic resins, methyl and carboxymethyl cellulose, guar, gelatin, zeins and alginates; (b) water; (c) a metal salt selected from the group consisting of water soluble palladium, copper, silver, gold and nickel salts; (d) a complex former for said metal; and (e) a reducing agent. The presence of a reducing agent is essential to the invention disclosed in US 4,253,875, which indicates that the catalyst is not deposited as such, but is generated in a post-deposition step.

Flexographic printing of a catalyst layer for the manufacturing of electromagnetic wave shield material is disclosed in JP patent 2002-223095A, but fails to disclose printing of a catalyst layer from a hydrophilic phase and suffers from the disadvantage of requiring relatively high viscosity inks, usually of the order of 200-600 mPa.s, for which binders are required. Other additives such as defoamers, waxes, surfactants, slip agents and plasticizers are often required to obtain the required printing properties. US 3,989,526 discloses a processing composition comprising a reducing agent and an inert transition metal complex oxidizing agent which undergo redox reaction in a liquid medium in the presence of catalytic material which is a zero valent metal or chalcogen of a Group VIII or IB element, wherein said liquid is a solvent for said reducing agent and said inert transition metal ion complex, said inert transition metal complex comprising (a) Lewis bases and (b) Lewis acids which are capable of existing in at least two valence 5 states and said oxidizing agent and said reducing agent being so chosen that (1) the reaction products thereof are noncatalytic for said oxidation-reduction reaction and (2) when test samples thereof are each dissolved in an inert solvent at a concentration of about 0.01 molar at 20⁰C, there is essentially no redox reaction between

W said oxidizing agent and said reducing agent, and said oxidizing agent being a complex of a metal ion with a liquid which, when a test sample thereof is dissolved at 0.1 molar concentration at 20⁰C in an inert solvent solution containing a 0.1 molar concentration of a tagged ligand of the same species which is uncoordinated, exhibits

15 essentially no exchange of uncoordinated and coordinated ligands for at least 1 minute. Application of the processing composition using printing techniques, such as by printing with a stamp, is disclosed in US 3,989,526.

Prior art processes have therefore realized patterns of an

20 electroless deposition catalyst by either modifying a uniform coating by local application of an energy source be it with heat, light, X-rays, electrons, ions or some other energy source, by contactless printing techniques, such as ink-jet, electrostatic or electrophotographic techniques, by relatively low resolution contact

25 printing processes such as screen printing or relatively slow contact printing processes such as stamp printing.

There is therefore a need for processes not involving multiple process steps with removal of material, which lend themselves to mass production of high resolution patterns of electroless

30 deposition catalysts. In respect of the catalyst, the avoidance of additives is preferred to prevent poisoning of the catalytic species and the resulting reduction in catalytic activity and to avoid embedding of the catalyst resulting in inaccessibility of the catalyst . 5

Prior art

Heretofore, the following documents relevant to the patentability present invention are known: 0 WO 01/88958 published on November 22, 2001

D. Hohnholz and A. MacDiarmid, in Synthetic Metals, volume 121, pages 1327-1328 (2001)

EP-A 1 415 826 published on May 6, 2004 US 3,356,030 published on December 5, 1967

US 3,532,532 published on October 6, 1970

US 3,797,388 published on March 19, 1974

GB 1,343,784A published on January 16, 1974 WO 99/27022A published on June 3, 1999

WO 03/057789A published on July 17, 2003

DE 4119348A published on December 17, 1992

US 4,981,517 published on January 1, 1991

WO 00/032705A published on June 8, 2000 US 2005/003101A published on January 6, 2005

DE 2757029A published on January 31, 1980

WO 92/21790A published on December 10, 1992

WO 93/04215A published on March 4, 1993

US 6,521,285 published on February 18, 2003 US 5,300,140 published on April 5, 1994

US 4,253,875 published on March 3, 1981

JP 2002-223095A published on August 9, 2002

US 3,989,526 published on November 2, 1976

Aspects of the invention

It is therefore an aspect of the present invention to provide a process for the mass production of patterns of electroless deposition catalysts. It is therefore a further aspect of the present invention to provide a high resolution process for the mass production of patterns of electroless deposition catalysts.

It is therefore also an aspect of the present invention to provide a process for producing a pattern of electroless deposition catalyst from aqueous media.

It is also an aspect of the present invention to provide a process for realizing a pattern of electroless deposition catalyst, which does not. require activation prior to electroless deposition.

Further aspects and advantages of the invention will become apparent from the description hereinafter.

Summary of the invention

Surprisingly it has been found that a high resolution pattern of an electroless deposition catalyst can be realized from aqueous media in a single step, without resorting to photographic techniques, in a low cost high speed process which lends itself to mass production. Moreover, the electroless deposition catalyst thereby deposited does not require activation prior to electroless deposition.

Aspects of the present invention are realized by a process comprising the step of: contact printing exclusive of stamp printing a pattern of an electroless deposition catalyst via a hydrophilic phase to a receiving medium, wherein the electroless deposition catalyst requires no activation prior to electroless deposition. Preferred embodiments are disclosed in the dependent claims.

Detailed description of the invention

Definitions

The term "aqueous medium" means a medium containing water and water-miscible organic solvents containing between 50% by weight of water and 100% by weight of water.

The term transparent layer as used in disclosing the present invention means permitting the passage of light in such a way that objects can be clearly seen through the layer. The term "layer", as used in disclosing the present invention, means a continuous coating unless qualified by the adjective "non- continuous" .

The term "pattern", as used in disclosing the present invention, means a non-continuous coating, which may be an array, arrangement or configuration of lines and/or shapes, areas and/or regions.

The term "functional" in the expression "functional patterns" as used in disclosing the present invention means having at least one function that is non-decorative, although functional materials as used in disclosing the present application may have a decorative function or utility in addition to a non-decorative function or utility. Examples of such functions are non-decorative colouring, pH-indicating, whitening, fluorescent, phosphorescent, X-ray phosphor, conductive properties and catalysis. The term functional pattern therefore includes patterns of catalytic species including electroless deposition catalysts.

The term "catalyst" in the expression "electroless deposition catalyst" as used in disclosing the present invention means a substance which alters the rate of a chemical reaction or physical process without itself being consumed i.e. it can accelerate or decelerate a chemical reaction e.g. electroless deposition. The term catalyst does not include species which of themselves have no electroless deposition catalytic properties, although they may be precursors of a species which does perform the function of an electroless deposition catalyst. Autocatalysts are here included in the term catalyst.

The term "electroless deposition", as used in disclosing the present invention, means deposition of conducting species, such as s metals, without using electrochemical techniques. Electroless deposition techniques usually involve a reaction between an oxidizing species and a reducing species.

The term "hydrophilic phase", as used in disclosing the present invention, means a phase with substantially hydrophilic properties

W i.e. containing or having an affinity for, attracting, adsorbing, or absorbing water. The hydrophilic phase mainly contains water and hydrophilic substances e.g. alcohols and cellulose derivatives, although small quantities of hydrophobic substances may be present. The term "flexible", as used in disclosing the present

/5 invention, means capable of following the curvature of a curved object such as a drum without being damaged.

The term "contact printing" otherwise known as impact printing, as used in disclosing the present invention, is defined as a printing process of applying ink to a substrate utilizing physical

20 contact between some part of the printing device and the substrate i.e. in which there is direct contact between the substrate to be printed and the delivery mechanism e.g. offset printing, flexographic printing, lithographic printing, letterpress printing, screen printing, gravure printing, rotogravure printing, intaglio

25 printing, stamp printing, wood-block printing and dye sublimation printing. "Contact printing" is thereby distinguished from non- contact printing processes, otherwise known as non-impact printing processes, which is a printing processes in which an ink is applied to a substrate without utilizing physical contact between some part

30 of the printing device and the substrate e.g. inkjet printing, laser printing, electrographic printing, electrophoretic printing and electrophotographic printing using solid or liquid toners. Neither coating nor spraying can be regarded as a printing process, since no printing is involved.

35 The term "printing ink", as used in disclosing the present invention, means an ink or one phase of a single fluid ink. The ink can be either hydrophilic i.e. accepted by the hydrophilic areas of a printing plate, roll or stamp, as used, for example, in reverse offset inks, or oleophilic i.e. accepted by the oleophilic areas of

40 a printing plate, roll or stamp, as used, for example, in conventional offset inks. It may or may not contain at least one dye and/or pigment as colorant (s) . The term "dye", as used in disclosing the present invention, means a coloring agent having a solubility of 10 mg/L or more in the medium in which it is applied and under the ambient conditions pertaining. The term "pigment", as used in disclosing the present invention, is defined in DIN 55943, herein incorporated by reference, as an inorganic or organic, chromatic or achromatic coloring agent that is practically insoluble in the application medium under the pertaining ambient conditions, hence having a solubility of less than 10 mg/L therein.

The term "binder", as used in disclosing the present invention, means a polymeric species, which may be naturally occurring material, a modified naturally occurring material or a synthetic material . The term "coated paper", as used in disclosing the present invention, means paper coated with any substance i.e. includes both clay-coated paper and resin-coated paper.

PET as used in the present disclosure represents poly (ethylene terephthalate) . The term "diffusion transfer reversal (DTR) process", as used in disclosing the present invention, refers to a process developed independently by A. Rott [GB patent 614,155 and Sci . Photogr., (2) 13, 151(1942)] and E. Weyde [DE patent 973,769] and described by G. I. P. Levenson in Chapter 16 of "The Theory of the Photographic Process Fourth Edition", edited by T. H. James, pages 466 to 480, Eastman Kodak Company, Rochester (1977), herein incorporated by reference.

The term "ionomer", as used in disclosing the present invention, means a polymer with covalent bonds between the elements of the chain, and ionic bonds between the chains e.g. metal salts of copolymers of ethylene and methacrylic acid commercialized by Du Pont under the tradename SURLYN®.

Printing processes

According to the process for contact printing exclusive of stamp printing a pattern of an electroless deposition catalyst of the present invention, the pattern of an electroless deposition catalyst is printed via a hydrophilic phase. According to a first embodiment of the process, according to the present invention, the pattern of electroless deposition catalyst consists of continuous areas of electroless deposition catalyst. According to a second embodiment of the process, according to the present invention, the contact printing process comprises the steps of: applying a pattern of an electroless deposition catalyst via a hydrophilic phase to an intermediate plate or roller and transferring the pattern of electroless deposition catalyst from the intermediate plate or roller to a receiving medium.

According to a third embodiment of the process, according to the present invention, the contact printing process comprises the steps of: applying a pattern of an electroless deposition catalyst via a hydrophilic phase to a printing plate master and transferring the pattern of electroless deposition catalyst from the printing plate master to a receiving medium.

Preferred printing techniques include conventional offset printing with an aqueous fountain and an oleophilic ink, reverse offset printing using a hydrocarbon or mineral oil as fountain medium and a hydrophilic ink, offset printing using single fluid inks consisting of a fine emulsion of the ink in the fountain or of a fine emulsion of the fountain in the ink ^vand driography using water-based driographic inks . Offset printing has the advantage of printing smooth continuous areas at very high speeds with high resolution. Evaporation of solvent and/or water from the offset fluids is very low in the printing press compared to e.g. screen printing.

Electroless deposition catalyst

According to the process for contact printing exclusive of stamp printing a pattern of an electroless deposition catalyst of the present invention, the pattern of an electroless deposition catalyst is printed via a hydrophilic phase.

Development nuclei of the type well known in diffusion transfer reversal (DTR) image receiving materials are preferred electroless deposition catalysts e.g. noble metal particles, such as silver particles, and colloidal heavy metal sulfide particles, such as colloidal palladium sulfide, nickel sulfide and mixed silver-nickel sulfide. These nuclei may be present with or without a binding agent .

According to a fourth embodiment of the process, according to the present invention, the electroless deposition catalyst is non- metallic e.g. palladium, silver, nickel, and cobalt sulphides.

According to a fifth embodiment of the process, according to the present invention, the electroless deposition catalyst is a heavy metal sulphide, e.g. palladium, silver, nickel, cobalt, copper, lead and mercury sulphides, or a mixed sulphide, e.g. silver-nickel sulphide.

According to a sixth embodiment of the process, according to the present invention, the electroless deposition catalyst is metallic e.g. silver, platinum, rhodium, iridium, gold, ruthenium, palladium and copper particles .

According to a seventh embodiment of the process, according to the present invention, the electroless deposition catalyst is capable of catalyzing silver deposition.

Hydrophilic phase

The hydrophilic phase may also contain: water-soluble gums, a pH buffer system, desensitizing salts, acids or their salts, wetting agents, solvents, non-piling or lubricating additives, emulsion control agents, viscosity builders, biocides and defoamers.

However, the presence of additives in the hydrophilic phase should be avoided if at all possible to prevent pollution/poisoning of the electroless deposition catalyst with resulting reduction in catalytic activity. According to an eighth embodiment of the process, according to the present invention, the hydrophilic phase only contains water and the electroless deposition catalyst.

According to a ninth embodiment of the process, according to the present invention, the hydrophilic phase further contains at least one water-miscible organic compound, such as aliphatic alcohols, ketones, arenes , esters, glycol ethers, cyclic ethers, such as tetrahydrofuran, and their mixtures, preferably an organic solvent.

According to a tenth embodiment of the process, according to the present invention, less than 10% by weight of the dissolved and dispersed solids in the hydrophilic phase is binder.

According to an eleventh embodiment of the process, according to the present invention, the hydrophilic phase is exclusive of a water-dispersible polymer.

According to a twelfth embodiment of the process, according to the present invention, the hydrophilic phase is exclusive of a reducing agent.

According to a thirteenth embodiment of the process, according to the present invention, less than 5% by weight of the dissolved and dispersed solids in the hydrophilic phase is binder. Minimalization of binder-content enables the catalyst species to exhibit maximum activity and prevents embedding of the electroless deposition catalyst species, making them non-accessible. According to a fourteenth embodiment of the process, according to the present invention, the hydrophilic phase is an aqueous fountain medium, such as used in conventional offset printing.

According to a fifteenth embodiment of the process, according to the present invention, the hydrophilic phase is a hydrophilic ink, such as used in reverse offset printing with an oleophilic fountain e.g. of a hydrocarbon or mineral oil, in which the electroless deposition catalyst may replace part or all of the dyes and/or pigments. Depending on the type of catalyst, it may be preferable to eliminate dyes, pigments or other additives from the ink to prevent pollution of the catalyst, thereby increasing the efficiency of the catalyst. In addition, this would result in a higher concentration of catalyst in the dried layer.

According to a sixteenth embodiment of the process, according to the present invention, the hydrophilic phase is a hydrophilic ink in which the concentration of electroless deposition catalyst is

— R between 10 and 1 mol/L, preferably between 0.001 and 0.1 mol/L.

According to a seventeeth embodiment of the process, according to the present invention, the hydrophilic phase is the dispersing phase of a single fluid ink, such as used in offset printing. The hydrophilic phase in single fluid inks is mainly based on ethylene glycols. To prevent coagulation and maintain a high efficiency of the catalyst, it may be necessary to replace part of the ethylene glycols with water.

According to an eighteenth embodiment of the process, according to the present invention, the hydrophilic phase is the dispersing phase of a single fluid ink and the electroless deposition catalyst is present in a concentration of between 10 and 1 mol/L, preferably between 0.001 and 0.1 mol/L.

According to a nineteenth embodiment of the process, according to the present invention, the hydrophilic phase is the dispersed phase of a single fluid ink, such as used in offset printing.

According to a twentieth embodiment of the process, according to the present invention, the hydrophilic phase is a water-based driographic ink, in which the electroless deposition catalyst may replace a part or all of the dyes and/or pigments. Depending on the type of catalyst, it may be preferable to eliminate dyes, pigments or other additives from the ink to prevent pollution of the catalyst, thereby possibly increasing its efficiency. In addition, this would result in a higher concentration of catalyst in the dried layer .

According to a twenty-first embodiment of the process, according to the present invention, the hydrophilic phase is a water-based 5 driographic ink, which contains electroless deposition catalyst in a concentration of between 10^~8 and 1 mol/L, preferably between 0.001 and 0.1 mol/L.

According to a twenty-second embodiment of the process, according to the present invention, the hydrophilic phase is W exclusive of an ionomer.

According to a twenty-third embodiment of the process, according to the present invention, the hydrophilic phase comprises other functional ingredients e.g. selected from the group consisting of fluorescent, phosphorescent, pH-indicating, coloring, whitening and 15 intrinsically conductive ingredients.

According to a twenty-fourth embodiment of the process, according to the present invention, the electroless deposition catalyst is incorporated into a hydrophilic phase, which has a viscosity at 25°C after stirring to constant viscosity of at least 20 30 mPa.s as measured according to DIN 53211 i.e. until successive measurements according to DIN 53211 are reproducible.

According to a twenty-fifth embodiment of the process, according to the present invention, the electroless deposition catalyst is incorporated in a hydrophilic phase, which has a viscosity at 25°C 25 after stirring to constant viscosity of at least 100 mPa.s as measured according to DIN 53211 i.e. until successive measurements according to DIN 53211 are reproducible.

According to a twenty-sixth embodiment of the process, according to the present invention, the electroless deposition catalyst is 30 incorporated into a hydrophilic phase, which has a viscosity at 25°C after stirring to constant viscosity of at least 200 mPa.s as measured according to DIN 53211 i.e. until successive measurements according to DIN 53211 are reproducible.

According to a twenty-seventh embodiment of the process, 35 according to the present invention, the electroless deposition catalyst is incorporated into a hydrophilic phase, which has a pH between 1.5 and 5.5.

Aqueous fountain medium

40

According to a twenty-eighth embodiment of the process, according to the present invention, the electroless deposition catalyst is incorporated into an aqueous fountain medium. According to a twenty-ninth embodiment of the process, according to the present invention, the electroless deposition catalyst is

—8 present in the fountain medium in a concentration of 10 to 1 mol/L, preferably between 0.001 and 0.1 mol/L. The aqueous fountain media may also contain: water-soluble gums, a pH buffer system, desensitizing salts, acids or their salts, wetting agents, solvents, non-piling or lubricating additives, emulsion control agents, viscosity builders, biocides and defoamers . According to a thirtieth embodiment of the process, according to the present invention, the electroless deposition catalyst is incorporated into an aqueous fountain medium, which further comprises an anti-foaming agent. Suitable anti-foaming agents include the silicone antifoam agent X50860A from Shin-Etsu.

According to a thirty-first embodiment of the process, according to the present invention, the electroless deposition catalyst is incorporated into an aqueous fountain medium, which further contains a water-soluble gum, such as gum arabic, larch gum, CMC, PVP, and acrylics .

Water-miscible organic compound

According to a thirty-second embodiment of the process, according to the present invention, the hydrophilic phase further contains at least one water-miscible organic compound, such as aliphatic alcohols, ketones, arenes, esters, glycol ethers, cyclic ethers, such as tetrahydrofuran, and their mixtures.

Oleophilic phase

According to a thirty-third embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process.

According to a thirty-fourth embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process and the oleophilic phase is an oleophilic fountain.

According to a thirty-fifth embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process and the oleophilic phase is the dispersed phase of a single fluid ink.

According to a thirty-sixth embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process and the oleophilic phase is the continuous phase of a single fluid ink.

According to a thirty-seventh embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process and the oleophilic phase is an oleophilic ink.

Pigments and dyes

According to the process for contact printing exclusive of stamp printing a pattern of an electroless deposition catalyst of the present invention, the pattern of an electroless deposition catalyst is printed via a hydrophilic phase and an oleophilic phase may be involved in the contact printing process .

According to a thirty-eighth embodiment of the process, according to the present invention, the hydrophilic phase contains at least one colorant, which may be a pigment or dye.

According to a thirty-ninth embodiment of the process, according to the present invention, the colorant in the hydrophilic phase is a dye . According to a fortieth embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process and the oleophilic phase contains a colorant, which may be a pigment or a dye.

According to a forty-first embodiment of the process, according to the present invention, an oleophilic phase is involved in the contact printing process and the oleophilic phase contains a dye.

The colorant may be selected from the group consisting of pigments and dyes, may either be present in the hydrophilic phase or in an oleophilic phase e.g. the dispersed phase in a single fluid ink, an oleophilic fountain in the case of reverse offset printing or the oleophilic "ink" in the case of conventional offset printing.

Transparent coloured compositions can be realized by incorporating pigments e.g. azo pigments e.g. DALMAR® Azo Yellow and LEVANYL® Yellow HRLF, dioxazine pigments e.g. LEVANYL® Violet BNZ, phthalocyanine blue pigments, phthalocyanine green pigments, Molybdate Orange pigments, Chrome Yellow pigments, Quinacridone pigments, Barium precipitated Permanent Red 2B, manganese precipitated BON Red, Rhodamine B pigments and Rhodamine Y pigments. Suitable dyes include:

O H

Direct =

Na

Yellow 86

(from

According to a forty-second embodiment of the process, according to the present invention, the hydrophilic and/or oleophilic phase contains a dye and/or a pigment such that the colour tone of the ink and the background cannot be distinguished by the human eye e.g. by colour matching or colour masking by for example matching the CIELAB a*, b* and L* values as defined in ASTM Norm E179-90 in a R (45/0) geometry with evaluation according to ASTM Norm E308-90.

Surfactants

According to a forty-third embodiment of the process, according to the present invention, the aqueous fountain medium further contains at least one surfactant i.e. at least one surfactant selected from the group consisting of cationic, anionic, amphoteric and non-ionic surfactants.

According to a forty-fourth embodiment of the process, according to the present invention, the aqueous fountain medium further contains at least one non-ionic surfactant e.g. ethoxylated/fluoro- alkyl surfactants, polyethoxylated silicone surfactants, polysiloxane/polyether surfactants, ammonium salts of perfluoro- alkylcarboxylic acids, polyethoxylated surfactants and fluorine- containing surfactants .

Suitable non-ionic surfactants include:

NONOl SURFYNOL® 440: an acetylene compound with two polyethylene oxide chains having 40wt% of polyethylene oxide groups from Air Products

NON02 SYNPERONIC®13 /6.55 a tridecylpolyethylene-glycol NON03 ZONYL® FSO-100: a mixture of ethoxylated fluorosurfactants

F (CF₂CF₂) i-₇CH₂CH₂O (CH₂CH₂O) _yH where y = 0 to ca. 15 from DuPont;

NON04 ARKOPAL™ N060: a nonylphenylpolyethylene-glycol from HOECHST NON05 FLUORAD® FC129: a fluoroaliphatic polymeric ester from 3M NON06 PLURONIC® L35 a polyethylene-glycol /propylene-glycol NON07 TEGOGLIDECS⁾ 410: a polysiloxane-polymer copolymer surfactant, from Goldschmidt; NON08 TEGOWET®: a polysiloxane-polyester copolymer surfactant, from Goldschmidt; NON09 FLUORAD® FC126: a mixture of ammonium salts of perfluorocarboxylic acids, from 3M;

NONlO FLUORAD® FC430: a 98.5% active fluoroaliphatic ester from 3M; NONIl FLUORAD® FC431: CF₃(CF₂)₇SO₂(C₂H₅)N-CH₂CO-(OCH₂CH₂)_nOH from 3M; N0N12 Polyoxyethylene-10-lauryl ether NON13 ZONYL® FSN: a 40% by weight solution of

F (CF₂CF₂) ₁-₉CH₂CH₂O (CH₂CH₂O)_xH in a 50% by weight solution of isopropanol in water where x = 0 to about 25, from DuPont;

NON14 ZONYL® FSN-IOO: F (CF₂CF₂) _!-₉CH₂CH₂O (CH₂CH₂O)_xH where x = 0 to about 25, from DuPont;

NON15 ZONYL® FS300; a 40% by weight aqueous solution of a fluorinated surfactant, from DuPont;

NONl 6 ZONYL® FSO : a 50% by weight solution of a mixture of ethoxylated fluoro-surfactants with the formula: F (CF₂CF₂) i_₇CH₂CH₂O (CH₂CH₂O) _γH where y = 0 to ca. 15 in a 50% by weight solution of ethylene glycol in water, from DuPont;

According to a forty-fifth embodiment of the process, according to the present invention, the aqueous fountain medium further contains at least one anionic surfactant. Suitable anionic surfactants include:

ANOl HOSTAPON® T a 95% concentrate of purified sodium salt of N- methyl-N-2-sulfoethyl-oleylamide, from HOECHST ANO2 LOMAR® D

ANO3 AEROSOL® OT an aqueous solution of 10g/L of the sodium salt of the di-2-ethylhexyl ester of sulphosuccinic acid from American Cyanamid

ANO4 DOWFAX 2Al a 45% by weight aqueous solution of a mixture of the sodium salt of bis (p-dodecyl, sulpho-phenyl)-ether and the sodium salt of (p-dodecyl, sulpho-phenyI)- (sulphophenyl)ether from Dow Corning

ANO5 SPREMI tetraethylammonium perfluoro-octylsulphonate ANO6 TERGO sodium 1-isobutyl , 4-ethyl-n-octylsulphate AN07 ZONYL® 7950 a fluorinated surfactant, from DuPont; ANO8 ZONYL® FSA a 25% by weight solution of

F (CF₂CF₂) _!-₉CH₂CH₂SCH₂CH₂COOLi in a 50% by weight solution of isopropanol in water, from DuPont;

ANO9 ZONYL® FSE: 14% by weight solution of

[F (CF₂CF₂ )i_₇CH₂CH₂O]_xP(O) (ONH₄) _y where x = 1 or 2 ; y = 2 or 1; and x + y = 3 in a 70% by weight solution of ethylene glycol in water, from DuPont; ANlO ZONYL® FSJ: 40% by weight solution of a blend of

F(CF₂CF₂)_I-_VCH₂CH₂O]_xP(O) (0NH₄)_y where x = 1 or 2 ; Y = 2 or 1; and x + y = 3 with a hydrocarbon surfactant in 25% by weight solution of isopropanol in water, from DuPont;

ANIl ZONYL® FSP 35% by weight solution of

[F(CF₂CF₂)_I-_VCH₂CH₂O]_xP(O) (ONH₄) _y where x = 1 or 2 ; y = 2 or 1 and x + y = 3 in 69.2% by weight solution of isopropanol in water, from DuPont;

AN12 ZONYL® UR: [F (CF₂CF₂ ) i-₇CH₂CH₂O] _XP (O) (OH) _y where x = 1 or 2 ; y =

2 or 1 and x + y = 3, from DuPont;

AN13 ZONYL® TBS: 33% by weight solution of F (CF₂CF₂) ₃_₈CH₂CH₂SO₃H in a

4.5% by weight solution of acetic acid in water, from DuPont;

AN14 ammonium salt of perfluoro-octanoic acid.

According to a forty-sixth embodiment of the process, according to the present invention, the aqueous fountain medium further contains at least one amphoteric surfactant. Suitable amphoteric surfactants include:

AMPOl AMBITERIC® H a 20% by weight solution of hexadecyldimethyl- ammonium acetic acid in ethanol

Receiving medium

According to a forty-seventh embodiment of the process, according to the present invention, the receiving medium is any receiving medium suitable for printing, which may be flexible or rigid. Flexible media include but are not limited to paper, carton, cardboard, coated paper, a metallic foil or a plastic sheet or a composite of any of these materials. Rigid media include but are not limited to glass, ceramics, epoxy resins or plastics or a composite of any of these materials.

According to a forty-eighth embodiment of the process, according to the present invention, the receiving medium is paper, coated paper, a metallic foil or a plastic sheet.

The receiving medium may be translucent, transparent or opaque. Suitable plastic sheets include a polymer laminate, a thermoplastic polymer foil or a duroplastic polymer foil e.g. made of a cellulose ester, cellulose triacetate, cellulose butyrate, cellulose nitrate, polypropylene, polycarbonate or polyester, with poly (ethylene terephthalate) or poly (ethylene naphthalene-1, 4-dicarboxylate) being particularly preferred. Coated papers include laminates of paper, cardboard or carton with one or more layers of a polymeric material such as polyethylene or polypropylene.

According to a forty-ninth embodiment of the process, according to the present invention, the receiving medium is coated with additional layers, such as a subbing layer or receiver layer to render the substrate additionally adherent and receptive. Any of the many subbing materials which are well known in e.g. the photographic arts can be used. Typical of such subbing materials are gelatin, vinyl polymers such as polyvinyl alcohol and numerous polymeric materials, as well as other chemical compounds and compositions.

Electroless deposition process

The electroless deposition catalyst can serve as nuclei for electroless plating. The use of electroless plating is well known to those skilled in the art and is for example used in PCB manufacturing. Different metals such as nickel, silver, copper, gold, gold alloys, platinum, ruthenium, rhodium, cobalt and cobalt alloys ["Electroless Plating - Fundamentals and Applications", edited by Glenn 0. Mallory and June B. Hajdu, William Andrew Publishing/Noyes (1990)] can be plated electrolessly .

According to a fiftieth embodiment of the process, according to the present invention, the process further comprises the step of electroless deposition on the pattern of electroless deposition catalyst .

According to a fifty-first embodiment of the process, according to the present invention, multiple layers of electroless deposition catalyst are printed sequentially to fabricate devices. Each layer can have a different pattern and can be followed by a necessary process step, e.g. developing or plating, before the next printing step is carried out.

Diffusion transfer reversal (DTR) process

According to a fifty-second embodiment of the process, according to the present invention, the process further comprises the step of electroless deposition on the pattern of electroless deposition catalyst by a diffusion transfer reversal process in which a pattern of development nuclei is physically developed via a silver salt.

For example, the three steps of printing development nuclei, a DTR process to convert the nuclei pattern to a conductive pattern and printing an insulating layer, can be repeated several times to create multilayered printed circuit boards. The printing of development nuclei and subsequent DTR to produce a conductive pattern, can be followed by the printing of enzymes for building in this way a (bio) sensor. According to a fifty-third embodiment of the process, according to the present invention, the process further comprises the step of electroless deposition on the pattern of electroless deposition catalyst by a diffusion transfer reversal process comprising developing the electroless deposition catalyst with an unexposed silver halide containing layer (transfer emulsion layer) on a substrate, the amount of silver halide in the transfer emulsion layer being preferably between 0.1 and 10 g/m AgNO₃ and particularly

2 preferably between 1 and 5 g/m and with a ratio of gelatin to silver halide in the range of 0.05 to 4.0. According to a fifty-fourth embodiment of the process, according to the present invention, the process further comprises the steps of electroless deposition on the pattern of electroless deposition catalyst by a diffusion transfer reversal process; and removal of the colored ink pattern which does not contain electroless deposition catalyst from the substrate, e.g. when the transfer emulsion layer is separated from the substrate after the DTR process. This will occur when the oleophilic colored ink in a conventional offset printing process has a low affinity towards the substrate, compared to the affinity towards the transfer emulsion layer. This is for example the case if the substrate is hydrophilic or has a hydrophilic coating layer, such as a gelatin layer. The advantage of the removal of the ink pattern, is that a second pattern of electroless deposition catalyst can be printed via the fountain medium, without the risk of poor transfer of the fountain medium from the offset blanket to the oleophilic ink-covered substrate regions. In case a first pattern of electroless deposition catalyst is (partially) overcoated with an oleophilic colored ink in a second print step, the electroless deposition catalyst will be less or no longer available to interact with chemicals with which the printed substrate is brought in contact. Removal of the oleophilic colored ink of the second print step via DTR would uncover the underlying layer of electroless deposition catalyst again, regaining its functionality.

Industrial application

The process according to the present invention can, for example, be used to produce conductive patterns for a multiplicity of applications including electroplating with metallic layers, sensors, the production of electrical circuitry for single and limited use items such as toys, in capacitive antennae as part of radiofrequency tags, in electroluminescent devices which can be used in lamps, 5 displays, back-lights e.g. LCD, automobile dashboard and keyswitch backlighting, emergency lighting, cellular phones, personal digital assistants, home electronics, indicator lamps and other applications in which light emission is required.

10 The invention is illustrated hereinafter by way of COMPARATIVE

EXAMPLES and INVENTION EXAMPLES. The percentages and ratios given in these examples are by weight unless otherwise indicated.

Receiving media:

/5

The coating solution for the adhesion promoting layer No. 01 has the following composition and was coated at 130 in²/!:

Copolymer of 88% vinylidene chloride, 10% methyl acrylate and 68.8 g 2% itaconic acid

Kieselsol ™ IOOF , a colloidal silica from BAYER 16.7 g

Mersolat T^M H, a surfactant from BAYER 0.36 g

Ultravon ™ W, a surfactant from CIBA-GEIGY 1.68 g

Water to make 1000 g

20

The coating solution for the subbing layer No . 02 has the following composition and was coated at 30 m²/!:

Gelatin 11.4 g

Kieselsol ™ 100F-30, a colloidal silica from BAYER 10.08 g

Ultravon ™ W, a surfactant from CIBA-GEIGY 0.4 g

Arkopal 0.2 g

Hexylene glycol 0.67 g

Trimethylolpropane 0.33 g Copolymer of 74% maleic acid, 25% styrene and 1% 0.03 g methylmethacrylate

Water to make 1000 g

The coating solution for the gelatin layer No. 03 has the following composition:

PE-coated paper No. 04 is a photographic paper from F. Schoeller, consisting of paper (166 g/m ) with a TiC>₂-containing PE layer (28 g/m²) , overcoated with a gelatin layer (0.25 g/m ) . The backside is a layer of 47% LDPE and 53% HDPE (24 g/m²) .

10

Example 1

Offset printing of development nuclei via the fountain as hydrophilic phase

15

The preparation of palladium sulphide physical development nuclei is described in the example of EP-A 0 769 723, herein incorporated by reference. From this example, solutions Al, Bl and Cl were used to prepare a nuclei dispersion with a concentration of

20 0.0038 mol/1. 10 grams of isopropanol was added to 90 grams of this dispersion. This was "fountain medium A".

10 grams of isopropanol was added to 90 grams of a dispersion of silver physical development nuclei with a concentration of 0.027 mol/1 Ag and an average particle size of 5-6 nm. This was "fountain

25 medium B" .

Printing experiments were carried out with a 360 offset printer from A. B. Dick with MT253 Yellow, a yellow offset ink from Sun Chemical, using a Thermostar™ P970/15 printing plate, receiving media 1 to 3 as described above and "fountain medium A" and

30 "fountain medium B". With both fountain media 150 prints were made without deterioration of the print quality, the non-printed areas containing the fountain dispersion were colourless.

The preparation of the silver chlorobromide emulsion and the preparation of the transfer emulsion layer were as disclosed in EP-A

35 769 723 except that the coverage of silver halide applied was

2 2 equivalent to 2.35 g/m of AgNO₃ instead of 2 g/m thereof. The transfer emulsion layer was processed in contact with the receiving media listed above at 25⁰C for 1 minute with an AGFA-GEVAERT™ CP297 developer solution and subsequently dried at room temperature. After carrying out this diffusion transfer reversal (DTR) J process, a silver gray pattern had been formed in the non-inked areas for both "fountain medium A" and "fountain medium B" and for receiving media 2 and 3, showing that development nuclei had been transferred to the receiving media during printing. No coloration was observed for receiving medium 1 after carrying out this io diffusion transfer reversal (DTR) process.

The silver areas on receiving medium 2 with "fountain medium A" showed a resistance of 1500 Ω/square. The silver areas on the other samples showed no conductivity. During separation of the transfer emulsion layer and the (hydrophilic) receiving media 2 and 3, the

/5 (hydrophobic) yellow ink was transferred to the transfer emulsion layer, while the yellow ink remained on receiving medium 1 after separation.

An additional copper layer was grown on top of the silver pattern by immersing it for 4 minutes in a reducer bath (Reducer

20 Neoganth 406 from Atotech) , followed by electroless plating in a copper bath (Printoganth PV from Atotech) for 30 minutes. Copper was only deposited on the silver pattern, resulting in a change from a gray to a copper-colored pattern.

25 Example 2

Increasing conductivity via a diffusion transfer reversal process

Development nuclei were printed via the "fountain medium A" on 30 receiving medium 2 and then developed via the diffusion transfer reversal process described in example 1. The resistance was 1500 Ω/square. The receiving medium was then developed for a second time via the diffusion transfer reversal process, using the same conditions as described before, resulting in a resistance of 100 35 Ω/square. Since the transfer emulsion layer did not have to be photoexposed, problems of misalignment of the transfer emulsion layer to the already patterned receiving medium did not occur.

A single DTR process step in which the contact time was increased from 1 to 3 minutes, did not give a reduction in surface 40 resistance compared with the two subsequent DTR processes. Example 3

Increasing conductivity via the fountain as hydrophilic phase

Solutions Al, Bl and Cl were prepared as given below:

The physical development nuclei were prepared, as described in the EXAMPLE in EP-A 0 769 723, by a double jet precipitation in which solution Al of (NH₄J₂PdCl₄ and solution Bl of sodium sulphide were added at a constant rate during 4 minutes to solution Cl containing sodium sulphide while stirring at 400 rpm. Subsequent to precipitation, the precipitated nuclei obtained were dialysed to a conductivity of 0.5 mS . A 250 g sample of this dispersion was concentrated by evaporation to 50 g and 5 g isopropanol was added. This was "fountain medium C".

Printing was performed as described in Example 1 on receiving medium 5, with both "fountain medium A" and "fountain medium C".

After DTR development was performed as described in Example 1, a silver grey pattern was formed in the non-inked areas with receiving medium 5 printed with both "fountain medium A" and "fountain medium C". With "fountain medium A", the silver areas showed no conductivity, whereas the surface resistance realized with "fountain medium C" was 20-500 Ω/square. Hence an increase in the development nuclei concentration in the fountain medium improved the amount of deposited silver and thus the conductivity. The conductivity could be increased even further by a second DTR process . In a typical example, the surface resistance decreased from 21 to 3.8 Ω/square.

Example 4

Increasing conductivity via the fountain as hydrophilic phase

"Fountain medium C" was prepared as described for Example 3. Printing was performed, as described in Example 1, on receiving medium 5, separately with both "fountain medium A" and "fountain medium C" . After DTR development was performed as described in Example 1, a silver grey pattern was formed in the non-inked areas with receiving medium 5 printed with both "fountain medium A" and "fountain medium C". With "fountain medium A", the silver areas showed no 5 conductivity, whereas the surface resistance realized with "fountain medium C" was 170 Ω/square . Hence an increase in the development nuclei concentration in the fountain medium improved the amount of deposited silver and thus the conductivity. The conductivity could be increased even further by a second DTR process, resulting in a W resistance of 30 Ω/square.

Example 5

Increasing conductivity via additional coating step

/5

Development nuclei were printed via the "fountain medium A" on receiving media 1, 2, 4 and 5 as described in Example 1. The prints were then overcoated with "fountain medium A" with a nominal wet coating thickness of 10 μm. The fountain medium dewetted the yellow 20 inked hydrophobic areas and preferentially covered the ^λ fountain areas'. After drying at room temperature, the prints were developed via DTR and dried, resulting in conductive patterns with the resistances shown in Table 1 below.

25 Table 1:

When DTR development was performed on thereby printed receiving media 2 to 5 , which all had a gelatin outermost layer, silver layers with surface resistances of 5 to 20 Ω/square were obtained, whereas

30 in absence of a gelatin outermost layer, as in receiving medium 1, no silver was deposited on the nuclei pattern.

It was further found that the surface resistance of the layer obtained by DTR-processing of the development nuclei on receiving medium 2 could be reduced by a factor of 7.6 upon sintering together the silver particles formed in the DTR process by heating with an energy of 1250 mJ/cm² using a IR diode laser (wavelength 830 nm) beam.

5 Example 6

Increasing conductivity via heat-treatment

A silver layer, obtained by DTR-processing of the development io nuclei on receiving medium 2 as described in Example 5, was exposed to an IR diode laser (wavelength 830 nm) beam with an energy of 1250 mJ/cm². As a result of the heat generated, the silver particles formed in the DTR process sintered together, thereby reducing the surface resistance from 13 Ω/square to 1.7 Ω/square.

/j A silver layer, obtained by DTR-processing of the development nuclei on receiving medium 2 was exposed to a photoflash lamp, having a setting of 40. As a result of the heat generated, the silver particles formed in the DTR process sintered together, thereby reducing the surface resistance from 13 Ω/square to 4 20 Ω/square.

Example 7

Increasing conductivity via electroless copper plating

25

Development nuclei were printed via the "fountain medium C" on receiving media 4 and 5 as described in Examples 3 and 4. After performing DTR development as described in Example 1, silver grey patterns were formed in the non-inked areas. The silver patterns 30 were dipped in a 0.5% solution of palladium chloride (pH adjusted to 1.5 with hydrochloric acid) for 0.5 seconds, then thoroughly rinsed with water and finally placed in an electroless copper plating solution with the composition given in Table 2 below.

35 Table 2 :

The surface resistances obtained after electroless plating for various times are shown in Table 3.

Table 3 :

The present invention may include any feature or combination of features disclosed herein either implicitly or explicitly or any generalisation thereof irrespective of whether it relates to the presently claimed invention. In view of the foregoing description W it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

1. A process comprising the step of: contact printing exclusive of stamp printing a pattern of an electroless deposition catalyst via a hydrophilic phase to a receiving medium, wherein said electroless deposition catalyst requires no activation prior to electroless deposition.

2. Process according to claim 1, wherein said contact printing process comprises the steps of: applying a pattern of an electroless deposition catalyst via a hydrophilic phase to a intermediate plate or roller and transferring said pattern of electroless deposition catalyst from said intermediate plate or roller to a receiving medium.

3. Process according to claim 2, wherein said intermediate plate is a printing plate master.

4. Process according to any one of claims 1 to 3 , wherein said electroless deposition catalyst is non-metallic.

5. Process according to any one of claims 1 to 4, wherein said electroless deposition catalyst is a heavy metal sulphide.

6. Process according to one of claims 1 to 3 , wherein said electroless deposition catalyst is metallic.

7. Process according to any one of claims 1 to 6, wherein said electroless deposition catalyst is capable of catalyzing silver deposition.

8. Process according to any one of claims 1 to 7, wherein said process for printing is an offset printing process.

9. Process according to any one of claims 1 to 8 , wherein said hydrophilic phase contains a colorant.

10. Process according to any one of claims 1 to 9, wherein said hydrophilic phase is the continuous phase of a single fluid ink.

11. Process according to any one of claims 1 to 10, wherein said hydrophilic phase is a hydrophilic ink.

12. Process according to any one of claims 1 to 9 and 11, wherein said hydrophilic phase is a water-based driographic ink.

13. Process according to any one of claims 1 to 11, wherein said 5 hydrophilic phase is an aqueous fountain.

14. Process according to claim 13, wherein said hydrophilic phase has a viscosity at 25°C after stirring to constant viscosity of at least 30 mPa.s as measured according to DIN 53211.

10

15. Process according to any one of claims 1 to 11, 13 and 14, wherein an oleophilic phase is involved in said contact printing process .

15 16. Process according to claim 15, wherein said oleophilic phase is an oleophilic fountain.

17. Process according to claim 15, wherein said oleophilic phase is the dispersed phase of a single fluid ink.

20

18. Process according to claim 15, wherein said oleophilic phase is an oleophilic ink.

19. Process according to claim 15, wherein said oleophilic phase 25 contains a colorant.

20. Process according to any of claims 1 to 19, further comprising the step of electroless deposition on said pattern of electroless deposition catalyst.

30

21. Process according to claim 20, wherein said electroless deposition is by a diffusion transfer reversal process.

22. Process according to claim 20, wherein silver is deposited on 35 said pattern upon contact with a layer containing silver halide particles and a developer.