The invention relates to a process for the production of strongly adherent coatings on inorganic or organic substrates, wherein a low-temperature plasma treatment, a corona discharge treatment or a flame treatment is carried out on the inorganic or organic substrate, one or more photoinitiators are applied to the inorganic or organic substrate by spraying processes, and the substrate so precoated with photoinitiator is provided with a final coating.

The adhesion properties of coatings (e.g. finishes, paints, printing inks or adhesives) on inorganic or organic substrates, especially on non-polar substrates such as polyethylene, polypropylene or fluorine-containing polyolefins, are frequently inadequate. For that reason additional treatments have to be carried out in order to achieve satisfactory results. The adhesion can be improved by first applying special priming coatings, so-called primers, and only then applying the desired coating thereto. A further possibility lies in exposing the substrates to be coated to a plasma treatment or corona treatment and then coating them, it being possible for a grafting process with e.g. acrylate monomers to be carried out between those two operations (J. Polym. ScL, Part A: Polym. Chem. 31, 1307-1314 (1993)). The production of low-temperature plasmas and the plasma-assisted deposition of thin organic or inorganic layers, both under vacuum conditions and under normal pressure, have been known for some time. Fundamental principles and applications are described, for example, by AT. Bell, "Fundamentals of Plasma Chemistry" in "Technology and Application of Plasma Chemistry", published by J.R. Holahan and AT. Bell, Wiley, New York (1974) or by H. Suhr, Plasma Chem. Plasma Process 3(1),1, (1983). Furthermore, in plasmas, it is possible to carry out polymerisation reactions that result in the deposition of polymeric layers that can be used as primers. Fundamental principles and applications are described, for example, by H. Biederman, Y. Osada "Plasma Polymerisation Processes" in "Plasma technology 3" published by L. Holland, Elsevier, Amsterdam 1992. It is also known that plastics surfaces can be subjected to a plasma treatment and as a result the subsequently applied finish exhibits improved adhesion to the plastics substrate. This is described by H. J. Jacobasch et al. in Farbe + Lack 99(7), 602-607 (1993) for low-tempera¬ ture plasmas under vacuum conditions and by J. Friedrich et al. in Surf. Coat. Technol. 59, 371-6(1993) for plasmas ranging from in vacuo up to normal pressure conditions, the low- temperature plasma changing into a corona discharge. A process similar to the kind mentioned at the beginning is known from WO 00/24527. That process describes the plasma treatment of substrates with immediate vapour-deposition and grafting-on of photoinitiators in vacuo. A disadvantage, however, is that vapour-deposition requires the use of vacuum apparatus and, because of low deposition rates, is not very effi¬ cient and is not suitable for industrial applications having high throughput rates. A similar process is disclosed in WO 03/064061. WO 99/06204 describes a corona treatment unit that enables the corona-treated substrate to be sprayed with an aerosol. In an information brochure (Nanotec S.r.1) produced by Nanotec S.r.l, a corresponding apparatus is described specifically for the treatment of web-shaped materials.

There is a need in the art for processes for the pretreatment of substrates that can readily be carried out in practice and are not too expensive in terms of apparatus, by means of which the subsequent coating of those substrates is improved.

It has now been found that coatings of photocurable compositions having especially good adherence can be obtained by applying to a substrate to be coated, after it has been sub¬ jected to a plasma treatment (low pressure and/or normal pressure plasmas), corona treat¬ ment or flame treatment, a reactive substance, e.g. a photoinitiator, in the form of a nano- layer by means of aerosol spray coating, and optionally drying and irradiating the substrate so treated. The substrates so pretreated are provided with a coating and cured. The resulting coatings exhibit surprisingly good adhesion which does not undergo any appreciable deterioration even after several days' storage or exposure to sunlight.

The invention therefore relates to a process for the production of a strongly adherent coating on an inorganic or organic substrate, wherein a) a low-temperature plasma treatment, a corona discharge treatment or a flame treatment is carried out on the inorganic or organic substrate, b) one or more chemically active substances or a solution, suspension or emulsion of one or more chemically active substances or mixtures of chemically active substances with mono¬ mers or/and oligomers containing at least one ethylenically unsaturated group are applied to the inorganic or organic substrate, and c) those afore-mentioned substances are optionally dried using suitable methods and are irradiated with electromagnetic waves, wherein the application of the solution, suspension or emulsion in process step b) is carried out in the form of an aerosol by means of a nano-spraying process.

The process is simple to carry out and allows a high throughput per unit of time since laborious application steps or slow crosslinking reactions are not required. The process is especially well suited to workpieces that are composed of different plastics and/or metals or types of glass and that, without pretreatment, would therefore exhibit different degrees of adhesion on the different components, or that, in the case of a conventional primer treatment, exhibit different affinities for the primer.

As chemically active substance ("reactive substance") in the sense of this Application there come into consideration: b1) liquid photoinitiators or a solution, suspension or emulsion of one or more photoinitiators or mixtures of photoinitiators with monomers or/and oligomers containing at least one ethylenically unsaturated group, or b2) at least one radical-forming initiator and at least one UV-absorber containing at least one ethylenically unsaturated group and/or at least one monomeric or oligomeric ethylenically unsaturated compound in the form of solutions, suspensions or emulsions, or b3) liquid electron or H donors or a solution, suspension or emulsion of one or more electron or H donors or mixtures of electron or H donors with monomers or/and oligomers containing at least one ethylenically unsaturated group, or b4) 1. at least one activatable initiator or 2. at least one activatable initiator and at least one ethylenically unsaturated compound in the form of solutions, suspensions or emulsions, wherein at least one function-controlling group which results in the attainment of desired surface properties of the treated substrate is incorporated in the activatable initiator and/or the ethylenically unsaturated compound, or b5) 1. at least one activatable initiator or 2. at least one activatable initiator and at least one ethylenically unsaturated compound in the form of solutions, suspensions or emulsions, wherein at least one group that interacts with a subsequently applied coating to impart adhesion or reacts with groups present therein is incorporated in the activatable initiator and/or the ethylenically unsaturated compound. In the process according to the invention, it is also possible for mixtures of various reactive substances b1), b2), b3), b4) and b5) to be present in the solution, emulsion or suspension. In addition to the described reactive substances b), i.e. the substances described in b1), b2), b3), b4) and b5), the solution, emulsion or suspension may also contain further additives, for example light stabilisers, antistatics, flow improvers, dispersants and adhesion promoters.

In the process according to the invention, after the reactive substance, e.g. the photoinitiator or photoinitiators, or a solution or dispersion thereof in a solvent or monomer, has or have been applied in the form of an aerosol to the substrate which has been plasma-, corona- or flame-pretreated and after any drying step for evaporating off any solvent used, a fixing step for the reactive substance, e.g. the photoinitiator, is carried out by exposure with UV/VIS light. In the context of this Application, the term "drying" includes both variants, both the removal of the solvent and the fixing of the reactive substance, e.g. the photoinitiator.

In step c) of the above-described processes, the drying, that is to say the removal of the solvent, is optional. That step can be omitted, for example, when no solvent was used, for example when a liquid photoinitiator, or a liquid reactive substance, was used. The fixing in step c) of the process by irradiation with electromagnetic waves, especially U V A/I S radiation, must be carried out. Suitable apparatus for drying and irradiation is described hereinbelow.

The invention relates also to a process for the production of strongly adherent coatings on an inorganic or organic substrate, wherein a) a low-temperature plasma treatment, a corona discharge treatment or a flame treatment is carried out on the inorganic or organic substrate, b) one or more chemically active substances or a solution, suspension or emulsion of one or more chemically active substances or mixtures of chemically active substances with monomers or/and oligomers containing at least one ethylenically unsaturated group are applied to the inorganic or organic substrate, and c) those afore-mentioned substances are optionally dried using suitable methods and are irradiated with electromagnetic waves, wherein the application of the solution, suspension or emulsion in process step b) is carried out in the form of an aerosol by means of a nano-spraying process, and d) the substrate so pre-coated with a specific nano-layer is provided with a further coating. Process step b) in the above-described process is preferably carried out under normal pres¬ sure. If, in process step b), mixtures of photoinitiators with monomers or/and oligomers are used, the use of mixtures of one or more photoinitiators with monomers is preferred.

A characteristic feature of the process according to the invention is application of the primer layer containing the reactive substance, e.g. the photoinitiator, in the form of an aerosol. In that manner, almost molecular layers of initiator are obtained on the substrate, the layer thickness of which is in the nanometre range of approximately 5-500 nm, e.g.5-100 nm, pref¬ erably 5-50 nm, e.g.5-10 nm. Such nano-layers are advantageous economically, since material consumption will be low. The nano-layers in question are regularly arranged layers, producing an especially homoge¬ neous surface. Application of the aerosol containing the active substance, e.g. the photoinitiator, according to process step b) is performed by means of spray devices that are known in the art and which, for example, are commercially available. Such devices are described, for example, by G. Bolte and S. Kluth in coatings 2/98, 38-40; G. Bolte in Flexo+Tief-Druck 2-2003, 8-12; WO 99/06204 and in an information brochure (Nanotec S.r.1) produced by Nanotec S.r.l. In contrast to normal, known spray-coating methods with droplet size ranges of 20 μm and more, in this case liquid droplets (containing solvent/water/chemically active material) of < 1 μm in various carrier gases, e.g. air, nitrogen, CO2, are used. The concentration of the chemically active substance, e.g. the photoinitiator, in that aerosol is typically < 20 % in solution, being approximately from 0.01 to 20 %, preferably from 0.1 to 20 %. By virtue of that concentration, after spreading of the droplets on the substrate and subsequent evaporation, or drying, of the solvent on the substrate, layer thicknesses of the chemically active substance, e.g. the photoinitiator, in the nanometre range are obtained. In order to produce a constant layer thickness, parameters such as droplet formation, droplet concentration and surface tension of the aerosol droplets have to be adjusted accordingly. Spray devices equipped to do so are, as already mentioned above, known in the prior art and are also commercially available.

Many possible ways of obtaining plasmas under vacuum conditions have been described in the literature. The electrical energy can be coupled in by inductive or capacitive means. It may be direct current or alternating current; the frequency of the alternating current may range from a few kHz up into the MHz range. A power supply in the microwave range (GHz) is also possible. The principles of plasma production and maintenance are described, for example, in the review articles by A.T. Bell and H. Suhr mentioned above.

As primary plasma gases it is possible to use, for example, He, argon, xenon, N2, O2, H2, steam or air.

The process according to the invention is not sensitive per se in respect of the coupling-in of the electrical energy.

The process can be carried out batchwise, for example in a rotating drum, or continuously in the case of films, fibres or woven fabrics. Such methods are known and are described in the prior art.

The process is preferably carried out under corona discharge conditions. Corona discharges are produced under normal pressure conditions, the ionised gas used being most frequently air. In principle, however, other gases and mixtures are also possible, as described, for example, in COATING Vol. 2001, No. 12, 426, (2001). The advantage of air as ionisation gas in corona discharges is that the operation can be carried out in an apparatus open to the outside and, for example, a film can be drawn through continuously between the discharge electrodes. Such process arrangements are known and are described, for example, in J. Adhesion Sci. Technol. VoI 7, No. 10, 1105, (1993). Three-dimensional workpieces can be treated with a free plasma jet, the contours being followed with the assistance of robots. The spray device for applying the aerosol can also be present e.g. in the corona discharge station itself.

The flame treatment of substrates is known to the person skilled in the art. Corresponding industrial apparatus, for example for the flame treatment of films, is commercially available. In such a treatment, a film is conveyed on a cooled cylindrical roller past the flame-treatment apparatus, which consists of a chain of burners arranged in parallel, usually along the entire length of the cylindrical roller. Details can be found in the brochures of the manufacturers of flame-treatment apparatus (e.g. esse Cl1 flame treaters, Italy). The parameters to be chosen are governed by the particular substrate to be treated. For example, the flame temperatures, the flame intensity, the dwell times, the distance between substrate and burner, the nature of the combustion gas, air pressure, humidity, are matched to the substrate in question. As flame gases it is possible to use, for example, methane, propane, butane or a mixture of 70 % butane and 30 % propane.

Process step b), that is to say the application of the reactive substance in the form of an aerosol, is carried out, for example, in the same apparatus as that in which the corona treat¬ ment was carried out (see, for example, the apparatus described in WO 99/06204). Prefera¬ bly, however, the pretreatment a) is carried out, the treated substrate is removed from the apparatus used, and then step b) is performed in a different apparatus, the substrate is removed and then drying and exposure is optionally carried out according to step c).

The inorganic or organic substrate to be treated can be in any solid form. The substrate is preferably in the form of a woven fabric, a fibre, a film or a three-dimensional workpiece. The substrate may be, for example, a thermoplastic, elastomeric, inherently crosslinked or cross- linked polymer, a metal oxide, a ceramic material, glass, a metal, leather or a textile.

The pretreatment of the substrate in the form of plasma-, corona- or flame-treatment can, for example, also be carried out immediately after the extrusion of a fibre or film, and also directly after film-drawing.

The inorganic or organic substrate is preferably a thermoplastic, elastomeric, inherently crosslinked or crosslinked polymer, a metal oxide, a ceramic material, a type of glass or a metal, especially a thermoplastic, elastomeric, inherently crosslinked or crosslinked polymer.

Examples of thermoplastic, elastomeric, inherently crosslinked or crosslinked polymers are listed below. 1. Polymers of mono- and di-olefins, for example polypropylene, polyisobutylene, poly- butene-1, poly-4-methylpentene-1 , polyisoprene or polybutadiene and also polymerisation products of cycloolefins, for example of cyclopentene or norbomene; and also polyethylene (which may optionally be crosslinked), for example high density polyethylene (HDPE), high density polyethylene of high molecular weight (HDPE-HMW), high density polyethylene of ultra-high molecular weight (HDPE-UHMW), medium density polyethylene (MDPE), low density polyethylene (LDPE), and linear low density polyethylene (LLDPE), (VLDPE) and (ULDPE). Polyolefins, that is to say polymers of mono-olefins, as mentioned by way of example in the preceding paragraph, especially polyethylene and polypropylene, can be prepared by various processes, especially by the following methods: a) by free radical polymerisation (usually at high pressure and high temperature); b) by means of a catalyst, the catalyst usually containing one or more metals of group IVb, Vb1 VIb or VIII. Those metals generally have one or more ligands, such as oxides, halides, alcoholates, esters, ethers, amines, alkyIs, alkenyls and/or aryls, which may be either π- or σ- coordinated. Such metal complexes may be free or fixed to carriers, for example to activated magnesium chloride, titanium(lll) chloride, aluminium oxide or silicon oxide. Such catalysts may be soluble or insoluble in the polymerisation medium. The catalysts can be active as such in the polymerisation or further activators may be used, for example metal alkyls, metal hydrides, metal alkyl halides, metal alkyl oxides or metal alkyl oxanes, the metals being elements of group(s) Ia, Ha and/or Ilia. The activators may have been modified, for example, with further ester, ether, amine or silyl ether groups. Such catalyst systems are usually referred to as Phillips, Standard Oil Indiana, Ziegler (-Natta), TNZ (DuPont), metallocene or Single Site Catalysts (SSC). 2. Mixtures of the polymers mentioned under 1), for example mixtures of polypropylene with polyisobutylene, polypropylene with polyethylene (for example PP/HDPE, PP/LDPE) and mixtures of different types of polyethylene (for example LDPE/HDPE). 3. Copolymers of mono- and di-olefins with one another or with other vinyl monomers, for example ethylene/propylene copolymers, linear low density polyethylene (LLDPE) and mixtures thereof with low density polyethylene (LDPE), propylene/butene-1 copolymers, propylene/isobutylene copolymers, ethylene/butene-1 copolymers, ethylene/hexene copoly¬ mers, ethylene/methylpentene copolymers, ethylene/heptene copolymers, ethylene/octene copolymers, propylene/butadiene copolymers, isobutylene/isoprene copolymers, ethylene/- alkyl acrylate copolymers, ethylene/alkyl methacrylate copolymers, ethylene/vinyl acetate copolymers and copolymers thereof with carbon monoxide, or ethylene/acrylic acid copoly¬ mers and salts thereof (ionomers), and also terpolymers of ethylene with propylene and a diene, such as hexadiene, dicyclopentadiene or ethyl idenenorbomene; and also mixtures of such copolymers with one another or with polymers mentioned under 1), for example poly- propylene-ethylene/propylene copolymers, LDPE-ethylene/vinyl acetate copolymers, LDPE- ethylene/acrylic acid copolymers, LLDPE-ethylene/vinyl acetate copolymers, LLDPE- ethylene/acrylic acid copolymers and alternately or randomly structured polyalkylene-carbon monoxide copolymers and mixtures thereof with other polymers, for example polyamides. 4. Hydrocarbon resins (for example C5-C9) including hydrogenated modifications thereof (for example tackifier resins) and mixtures of polyalkylenes and starch. 5. Polystyrene, poly(p-methylstyrene), poly(α-methylstyrene). 6. Copolymers of styrene or α-methylstyrene with dienes or acrylic derivatives, for example styrene/butadiene, styrene/acrylonitrile, styrene/alkyl methacrylate, styrene/buta- diene/alkyl acrylate and methacrylate, styrene/maleic anhydride, styrene/acrylonitrile/methyl acrylate; high-impact-strength mixtures consisting of styrene copolymers and another poly¬ mer, for example a polyacrylate, a diene polymer or an ethylene/propylene/diene terpolymer; and also block copolymers of styrene, for example styrene/butadiene/styrene, styrene/- isoprene/styrene, styrene/ethylene-butylene/styrene or styrene/ethylene-propylene/styrene. 7. Graft copolymers of styrene or α-methylstyrene, for example styrene on polybutadi- ene, styrene on polybutadiene/styrene or polybutadiene/acrylonitrile copolymers, styrene and acrylonitrile (or methacrylonitrile) on polybutadiene; styrene, acrylonitrile and methyl meth¬ acrylate on polybutadiene; styrene and maleic anhydride on polybutadiene; styrene, acrylo¬ nitrile and maleic anhydride or maleic acid imide on polybutadiene; styrene and maleic acid imide on polybutadiene, styrene and alkyl acrylates or alkyl methacrylates on polybutadiene, styrene and acrylonitrile on ethylene/propylene/diene terpolymers, styrene and acrylonitrile on polyalkyl acrylates or polyalkyl methacrylates, styrene and acrylonitrile on acrylate/butadiene copolymers, and mixtures thereof with the copolymers mentioned under 6); such as those known, for example, as so-called ABS, MBS, ASA or AES polymers. 8. Halogen-containing polymers, for example polychloroprene, chlorinated rubber, chlorinated and brominated copolymer of isobutylene/isoprene (halobutyl rubber), chlorinated or chlorosulfonated polyethylene, copolymers of ethylene and chlorinated ethylene, epichlorohydrin homo- and co-polymers, especially polymers of halogen-containing vinyl compounds, for example polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, poly- vinylidene fluoride; and copolymers thereof, such as vinyl chloride/vinyl idene chloride, vinyl chloride/vinyl acetate or vinylidene chloride/vinyl acetate. 9. Polymers derived from α,β-unsaturated acids and derivatives thereof, such as poly- acrylates and polymethacrylates, or polymethyl methacrylates, polyacrylamides and poly- acrylonitriles impact-resistant-modified with butyl acrylate. 10. Copolymers of the monomers mentioned under 9) with one another or with other unsaturated monomers, for example acrylonitrile/butadiene copolymers, acrylonitrile/alkyl acrylate copolymers, acrylonitrile/alkoxyalkyl acrylate copolymers, acrylonitrile/vinyl halide copolymers or aery Io n itrile/al kyl methacrylate/butadiene terpolymers. 11. Polymers derived from unsaturated alcohols and amines or their acyl derivatives or acetals, such as polyvinyl alcohol, polyvinyl acetate, stearate, benzoate or maleate, poly- vinylbutyral, polyallyl phthalate, polyallylmelamine; and the copolymers thereof with olefins mentioned in Point 1. 12. Homo- and co-polymers of cyclic ethers, such as polyalkylene glycols, polyethylene oxide, polypropylene oxide or copolymers thereof with bisglycidyl ethers. 13. Polyacetals, such as polyoxymethylene, and also those polyoxymethylenes which contain comonomers, for example ethylene oxide; polyacetals modified with thermoplastic polyurethanes, acrylates or MBS. 14. Polyphenylene oxides and sulfides and mixtures thereof with styrene polymers or polyamides. 15. Polyurethanes derived from polyethers, polyesters and polybutadienes having termi¬ nal hydroxyl groups on the one hand and aliphatic or aromatic polyisocyanates on the other hand, and their initial products. 16. Polyamides and copolyamides derived from diamines and dicarboxylic acids and/or from aminocarboxylic acids or the corresponding lactams, such as polyamide 4, polyamide 6, polyamide 6/6, 6/10, 6/9, 6/12, 4/6, 12/12, polyamide 11, polyamide 12, aromatic polyamides derived from m-xylene, diamine and adipic acid; polyamides prepared from hexamethylene- diamine and iso- and/or tere-phthalic acid and optionally an elastomer as modifier, for exam¬ ple poly-2,4,4-trimethylhexamethylene terephthalamide or poly-m-phenylene isophthalamide. Block copolymers of the above-mentioned polyamides with polyolefins, olefin copolymers, ionomers or chemically bonded or grafted elastomers; or with polyethers, for example with polyethylene glycol, polypropylene glycol or polytetramethylene glycol. Also polyamides or copolyamides modified with EPDM or ABS; and polyamides condensed during processing ("RIM polyamide systems"). 17. Polyureas, polyimides, polyamide imides, polyether imides, polyester imides, poly- hydantoins and polybenzimidazoles. 18. Polyesters derived from dicarboxylic acids and dialcohols and/or from hydroxycarbox- ylic acids or the corresponding lactones, such as polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylolcyclohexane terephthalate, polyhydroxybenzoates, and also block polyether esters derived from polyethers with hydroxyl terminal groups; and also polyesters modified with polycarbonates or MBS. 19. Polycarbonates and polyester carbonates. 20. Polysulfones, polyether sulfones and polyether ketones. 21. Crosslinked polymers derived from aldehydes on the one hand and phenols, urea or melamine on the other hand, such as phenol-formaldehyde, urea-formaldehyde and mela- mine-formaldehyde resins. 22. Drying and non-drying alkyd resins. 23. Unsaturated polyester resins derived from copolyesters of saturated and unsaturated dicarboxylic acids with polyhydric alcohols, and also vinyl compounds as crosslinking agents, and also the halogen-containing, difficultly combustible modifications thereof. 24. Crosslinkable acrylic resins derived from substituted acrylic esters, e.g. from epoxy acrylates, urethane acrylates or polyester acrylates. 25. Alkyd resins, polyester resins and acrylate resins that are crosslinked with melamine resins, urea resins, isocyanates, isocyanurates, polyisocyanates or epoxy resins. 26. Crosslinked epoxy resins derived from aliphatic, cycloaliphatic, heterocyclic or aromatic glycidyl compounds, e.g. products of bisphenol-A diglycidyl ethers, bisphenol-F diglycidyl ethers, that are crosslinked using customary hardeners, e.g. anhydrides or amines with or without accelerators. 27. Natural polymers, such as cellulose, natural rubber, gelatin, or polymer-homologously chemically modified derivatives thereof, such as cellulose acetates, propionates and butyr- ates, and the cellulose ethers, such as methyl cellulose; and also colophonium resins and derivatives. 28. Mixtures (polyblends) of the afore-mentioned polymers, for example PP/EPDM, poly- amide/EPDM or ABS, PVC/EVA, PVC/ABS, PVC/MBS, PC/ABS, PBTP/ABS, PC/ASA, PC/PBT, PVC/CPE, PVC/acrylates, POM/thermoplastic RUR, PC/thermoplastic PUR, POM/acrylate, POM/MBS, PPO/HIPS, PPO/PA 6.6 and copolymers, PA/HDPE, PA/PP, PA/PPO, PBT/PC/ABS or PBT/PET/PC.

In the case of natural polymers, the following are to be mentioned as being especially preferred: carbon fibres, cellulose, starch, cottonwool, natural rubber, colophonium, wood, flax, sisal, polypeptides, polyamino acids and derivatives thereof.

The substrate can, for example, be one as used in the commercial printing sector, for bed intaglio printing, bed offset printing or continuous printing, posters, calendars, forms, labels, packaging films, tapes, credit cards, furniture profiles, etc.. The substrate is not confined to use in the non-nutrition sector. The substrate may also be, for example, a material for use in the field of nutrition, e.g. as packaging for foodstuffs; cosmetics, medicaments, efc..

When substrates have been pretreated according to processes of the invention it is also possible, for example, for substrates that usually have poor compatibility with one another to be adhesively bonded to one another or laminated.

Within the context of the present invention, paper should also be understood as being an inherently crosslinked polymer, especially in the form of card(board), which can additionally be coated with e.g. Teflon®. Such substrates are, for example, commercially available.

The thermoplastic, crosslinked or inherently crosslinked plastics is preferably a polyolefin, polyamide, polyacrylate, polycarbonate, polystyrene or an acrylic/melamine, alkyd or poly- urethane surface-coating.

Polycarbonate, polyethylene and polypropylene are especially preferred.

The plastics may be, for example, in the form of films, injection-moulded articles, extruded workpieces, fibres, felts or woven fabrics.

As inorganic substrates there come into consideration especially glass, ceramic materials, metal oxides and metals. They may be silicates and semi-metal or metal oxide glasses which are in the form of layers or in the form of powders preferably having average particle diame¬ ters of from 10 nm to 2000 μm. The particles may be dense or porous. Examples of oxides and silicates are SiO2] TiO2, ZrO2, MgO, NiO, WO3, AI2O3, La2O3, silica gels, clays and zeolites. Preferred inorganic' substrates, in addition to metals, are silica gels, aluminium oxide, titanium oxide and glass and mixtures thereof.

As metal substrates there come into consideration especially Fe, Al, Ti, Ni, Mo, Cr and steel alloys. Especially suitable metal substrates are aluminium, chromium, steel and vanadium, which are used, for example, for the manufacture of high-quality mirrors, such as, for example, telescope mirrors or vehicle headlamp mirrors. Aluminium is especially preferred. Especially interesting is a process wherein, in process step b), liquid photoinitiators or a solution, suspension or emulsion of one or more photoinitiators or mixtures of photoinitiators with monomers or/and oligomers containing at least one ethylenically unsaturated group, are used as chemically active substance b1 ).

In principle any compounds and mixtures that form one or more free radicals when irradiated with electromagnetic waves are suitable for use in the process according to the invention as photoinitiators in process step b1 ). These include initiator systems consisting of a plurality of initiators and systems that function independently of one another or synergistically. In addi¬ tion to coinitiators, for example amines, thiols, borates, enolates, phosphines, carboxylates and imidazoles, it is also possible to use sensitisers, for example acridines, xanthenes, thiazenes, coumarins, thioxanthones, triazines and dyes. A description of such compounds and initiator systems can be found e.g. in Crivello J.V., Dietliker K.K., (1999): Chemistry & Technology of UV & EB Formulation for Coatings, Inks & Paints, and in Bradley G. (ed.) Vol. 3: Photoinitiators for Free Radical and Cationic Polymerisation 2nd Edition, John Wiley & Son Ltd. The photoinitiator suitable for the process according to the invention in step b) may be either an initiator having an unsaturated group or an initiator not having such a group. Such compounds and derivatives are derived, for example, from the following classes of compounds: benzoins, benzil ketals, acetophenones, hydroxyalkylphenones, arninoalkyl- phenones, acylphosphine oxides, acylphosphine sulfides, acyloxyiminoketones, alkylamino- substituted ketones, such as Michler's ketone, peroxy compounds, dinitrile compounds, halogenated acetophenones, phenylglyoxalates,-dimeric phenylglyoxalates, benzophenones, oximes and oxime esters, thioxanthones, coumarins, ferrocenes, titanocenes, onium salts, sulfonium salts, iodonium salts, diazonium salts, borates, triazines, bisimidazoles, poly- silanes and dyes. It is also possible to use combinations of the compounds from the mentioned classes of compounds with one another and combinations with corresponding coinitiator systems and/or sensitisers.

Preferably, the photoinitiator is a compound of formula I or Ia

(RG)-A-(IN) (I), (IN)-A-(RG')-A-(IN) (Ia), wherein

(IN) is a photoinitiator basic structure; A is a spacer group or a single bond; (RG) is hydrogen or at least one functional ethylenically unsaturated group; and (RG') is a single bond or a divalent radical containing at least one functional ethylenically unsaturated group, or is a trivalent radical.

Preferably, in the compounds of formula I or Ia, (IN) is a photoinitiator basic structure of formula (II) or (III) x. (II), -P-R3 (III); R4

Ri is a group (A), (B), (C) or (III)

^ V~ 5 (A), -CR6R7R8 (B), -C-fOCiyay-OR^ (C); =^R2 n is a number from 0 to 6; R2 is hydrogen, C1-C12alkyl, halogen, the group (RG)-A- or, when R1 is a group (A), two radicals R2 in the ortho-position with respect to the carbonyl group may together also be -S-

or — c — ; R3 and R4 independently of each other are C1-C6all<yl, C1-C6alkanoyl, phenyl or benzoyl, each of the radicals phenyl and benzyl being unsubstituted or substituted by halogen, CrC6alkyl, CrC6alkylthio or CrC6alkoxy; R5 is hydrogen, halogen, CrC12alkyl or CrCi2alkoxy or the group (RG)-A-;

R6 is OR9 or N(Rg)2 or is -N^Λ , -NN NH , -N^ /N-R10 , -N/ o Or SO2R9;

R7 and R8 independently of each other are hydrogen, C1-C12alkyl, C2-C12alkenyl, CrCi2- alkoxy, phenyl or benzyl or R7 and R8 together are C2-C6alkylene; R9 is hydrogen, CrC6alkyl or CrC6alkanoyl; R10 is hydrogen, C1-C12alkyl or phenyl;

Rn is CrC4alkyl or -c-c-C<f2 > and 'R5 Xi is oxygen or sulfur. (IN) is, for example, a group \J~CΛ //

H3 ^ ■ ^ b HOo

" vS — P. — r: J' N) — C— C— N O or κ-r C CHH3 W -c-r— rr. —\ Λ\ // O O Il Il H,C VCH3 ^ /r C-C-OCH,

// = %/J C"Γ ?ΛH2~\J^CH3 ' ~Λ ,= /\- ffC- ffC-(OCH2CH2)2-O- &C- &C-^ /=J\> H3C XCH3

A in the compounds of formula I or Ia is, for example, a single bond or a spacer group O -Z-[(A,)a-Y]c-[(A2)b-X]ύ-, __z_|_(Ai)_γ^{i_(A2)_o^- ,

O O CH3CI O -O-tA^-C-fO-(A2)6-tθ-C-(A1)-O- or -N-N+-CH2CH2O-C- . CH3 X, Y and Z independently of one another are a single bond, -O-, -S- ,-N(R1O)-, -(CO)-, -(CO)O-, -(CO)N(R10)-, -0-(CO)-, -N(R10HCO)- or -N(R10)-(CO)O- . A1 and A2 independently of each other are, for example, C1-C4alkylene) C3-C12cycloalkylene, phenylene, phenylene-CrC4alkylene or C1-C4a!kylene-phenylene-C1-C4alkylene. a, b, c and d independently of one another are the numbers O to 4.

Special preference is given to compounds of formula I or Ia wherein A is a spacer group -Z-[(CH2)a-Y]c-[(CH2)b-X]d- and X, Y, Z, a, b, c and d are as defined above.

In the compounds of formula I or Ia, (RG) is hydrogen or RcRbC=CRa-, especially R0RbC=CRa-;

(RG1) is a single bond, H3C-Si- or — c— c— , especially H3C-Sh- or -C-C- Rh

and Ra, Rb and R0 independently of one another are hydrogen or CrC6alkyl, especially hydro¬ gen or methyl.

The preparation of such photoinitiator compounds is familiar to the person skilled in the art and has already been described in a large number of publications. For example, compounds containing unsaturated groups can be prepared by reacting 4-[2- hydroxyethoxy)-benzoyl]-1-hydroxy-1-methyl-ethane (Irgacure® 2959, Ciba Specialty Chemicals) with isocyanates containing acryloyl or methacryloyl groups or with other com¬ pounds containing acryloyl or methacryloyl groups, see e.g. US 4922004. Commercially available unsaturated photoinitiators are, for example, 4-(13-acryloyl- I^J.IO.IS-pentaoxatridecyO-benzophenone (Uvecryl P36 from UCB), 4-benzoyl-N,N-di- methyl-N-[2-(1-oxo-2-propenyl)oxy]ethylphenylmethanaminium chloride (Quantacure ABQ from Great Lakes), and, for example, some copolymerisable unsaturated tertiary amines (Uvecryl P101, Uvecryl P104, Uvecryl P105, Uvecryl P115 from UCB Radcure Specialties) or copolymerisable aminoacrylates (Photomer 4116 and Photomer 4182 from Ackros; Laromer LR8812 from BASF; CN381 and CN386 from Cray Valley). Further specific examples of suitable photoinitiator compounds having an ethylenically unsaturated function, and the preparation thereof, are to be found in the publications indicated below: Unsaturated acetophenone and benzophenone derivatives are described, for example, in US 3214492, US 3429852, US 3622848 and US 4304895, for O "' ' example fT^r^-rf^ o ■ Also suitable, for example, are

O H c=c-c-o-4f^Tc∏/^k-o -!L-C=CH and furtner copolymerisable benzophenones, e.g. from H \^ \^^ H

UCB, Ebecryl P36 or in the form of Ebecryl P38 diluted in 30 % tripropylene glycol diacrylate. Copolymerisable, ethylenically unsaturated acetophenone compounds can be found, for P. CH3 O example, in US 4922004, for example [P^pc-f-o-c-^cH, or CH,

P CH, HaC— -C_JL0_{CH2)_0_/' y_{i_i 0H ■ 2-Acryloyl-thioxanthone has been published in Eur. Polym. J. 23, 985 (1987). Examples such as are

described in DE 2818763. Further unsaturated carbonate-group-containing photoinitiator compounds can be found in EP 377191. Uvecryl® P36 (already mentioned above), from UCB, is a benzophenone bonded to an acrylic function by ethylene oxide units (see Tech¬ nical Bulletin 2480/885 (1985) from UCB or New. Polym. Mat. I, 63 (1987)):

C K^rT I\^^h<OCH2CH,)4-O- »C-C=CH2

CH, HOrcΛ\ HCH2)2-O- 3C-C--δCH—' Cu~O-(CH2) ,2 _-O // w has been published in Ho CH, /

Chem. Abstr. 128: 283649r. DE 19501025 gives further suitable ethylenically unsaturated photoinitiator compounds. Examples are 4-vinyloxycarbonyloxybenzophenone, 4-vinyloxycarbonyloxy-4'-chlorobenzo- phenone, 4-vinyloxycarbonyloxy-4'-methoxybenzophenone, N-vinyloxycarbonyl-4-amino- benzophenone, vinyloxycarbonyloxy-4'-fluorobenzophenone, 2-vinylo:.xycarbonyloxy-4I-meth- oxybenzophenone, 2-vinyloxycarbonyloxy-5-fluoro-4'-chlorobenzophienone, 4-vinyloxycar- bonyloxyacetophenone, 2-vinyloxycarbonyloxyacetophenone, N-vinyloxycarbonyl-4-amino- acetophenone, 4-vinyloxycarbonyloxybenzil, 4-vinyloxycarbonyloxy-4"-methoxybenzil] vinyl- oxycarbonylbenzoin ether, 4-methoxybenzoinvinyloxycarbonyl ether, phenyl(2-vinyloxycar- bonyloxy^-propylj-ketone, (4-isopropylphenyl)-(2-vinyloxycarbonyloxy-2-propyl)-ketone, phenyl-(1-vinyloxycarbonyloxy)-cyclohexyl ketone, 2-vinyloxycarbonyloxy-9-fluorenone, 2-(N- vinyloxycarbonyl)-9-aminofluorenone, 2-vinylcarbonyloxymethylanthraquinone, 2-(N-vinyloxy- carbonyl)-aminoanthraquinone, 2-vinyloxycarbonyloxythioxanthone, 3-vinylcarbonyloxythio-

CH2O-C-O-C=CH2 xanthone and H OCH2CH2-COOH

US 4672 079 discloses inter alia the preparation of 2-hydroxy-2-methyl(4-vinylpropiophe- none), 2-hydroxy-2-methyl-p-(1~methylvinyl)propiophenoneJ p-vinylbemzoylcyclohexanol, p- (i-methylvinyl)benzoyl-cyclohexanol. Also suitable are the reaction products, described in JP Kokai Hei 2-29*2307, of 4-[2-hydroxy- ethoxy)-benzoyl]-1-hydroxy-1-methyl-ethane (Irgacure® 2959, Ciba Specialty Chemicals) and isocyanates containing acryloyl or methacryloyl groups, for example

R Q „ o CH H2C=C-OCH2CH2 ,-—N N-—a p. — O nCnHH2.CcHH2^--Oo- — ^ ^ ^ ^) —-C c-—C c-—O OHH or CH,

CH, ff 9H3 C OCH2CH ljro-fyi-|-c OH (wherein R= H or CH3). ^- ' CH3

g C J—- OO—- CCHH2-CCHH-2CO-C-C=CH2

Further examples of suitable photoinitiators are and

o Il H2C=C-C-OCH2CH ,2_*-/ \N I Cf— ^ C— NΓΛ 0 H CH3

The following examples are described in Radcure '86, Conference Proceedings, 4-43 to 4-54

by W. Baumer et a/. H2C=C-C-O-(CH2)-O-^Γ~\-LΓO-I-C= H CH^ CH3

HC=CH2 HC = CH,

-C-C-O-C-C=CH2 H N> — c — c — ^ h ?

H2C=C-Lθ-(CH2)2-O-/^§_/Λ ■

G. Wehner et al. report in Radtech '90 North America on

H2C=C-O — (CH2)2- c—c— OH ■ In the process according to the invention, there H CH,

are also suitable the compounds presented at RadTech 2002, North America O CH, .0-(CHj)5-C-^OCH2CH2-O-/ /-C-C C-OH CH3 Q CH. I l T ' /f~\ Il I , wherein x, y and z are an average of 3 H3C-SI; O-tCH2)— C-^-OCH2CH2-O — </ J — C C-—C C— < OH CH3 Il -, J-\ P if, ? V iH∏333 O-(CH2)5—C-Jj-OCH2CH2-O-V V-C-C-' OH CH,

(SiMFPI2) and ° r i ° (MFPITX)

In the process according to the invention, it is possible to use either saturated or unsaturated photoinitiators. Preferably, unsaturated photoinitiators are used. Preference is therefore given to a process wherein the chemically active substance in process step b) is a photoinitiator containing an unsaturated group.

In the process according to the invention it is, of course, also possible to employ mixtures of different photoinitiators, for example mixtures of saturated and unsaturated photoinitiators.

Photoinitiators not having an unsaturated group are known to the person skilled in the art and are commercially available in a considerable diversity and number. In principle, all photo¬ initiators that after plasma treatment, corona treatment or flame treatment adhere to the surface of the particular substrate treated are suitable in the process.

The meanings of the substituents defined in formulae I and Ia in the various radicals are explained below.

CrCi2Alkyl is linear or branched and is, for example, CrC8-, CrC6- or CrC4-alkyl. Examples are methyl, ethyl, propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, 2,4,4-trimethyl-pentyl, 2-ethylhexyl, octyl, nonyl, decyl, undecyl or dodecyl, especially, for example, methyl or butyl. CrCβAlkyl and CrC4alkyl are also linear or branched and have, for example, the meanings given above up to the corresponding number of carbon atoms. CrC6AIlCyI substituents for benzoyl or phenyl are especially CrC4alkyl, for example methyl or butyl. Halogen is fluorine, chlorine, bromine or iodine, especially chlorine or bromine, preferably chlorine.

When R1 is a group (A), and two radicals R2 in the ortho-position with respect to the carbonyl group are together also -S- or -(C=O)-, then, for example, structures having the thioxanthone o basic structure ( ,„RG„,)-A Δ-H rf-^V ^Y^ -iLR8 or the anthraquinone basic structure

(RG) — A-H+- 7 Y 4-R, are produced;

C1-C6alkanoyl is linear or branched and is, for example, C1-C4alkanoyl. Examples are formyl, acetyl, propionyl, butanoyl, isobutanoyl, pentanoyl and hexanoyl, preferably acetyl. C1-C4Alkanoyl has the meanings given above up to the corresponding number of carbon atoms.

CrCi2Alkoxy is a linear or branched radical and is, for example, CrC8-, C1-C6- or d-C4- alkoxy. Examples are methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, sec-butoxy, isobut- oxy, tert-butoxy, pentyloxy, hexyloxy, heptyloxy, 2,4,4-trimethylpentyloxy, 2-ethylhexyloxy, octyloxy, nonyloxy, decyloxy and dodecyloxy, especially methoxy, ethoxy, propoxy, isopro¬ poxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, preferably methoxy. CrCβAlkoxy, C1-Cδ- alkoxy and CrC4alkoxy are also linear or branched and have, for example, the meanings given above up to the corresponding number of carbon atoms.

C1-CβAlkylthio is a linear or branched radical and is, for example, CrC4alkylthio. Examples are methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, sec-butylthio, isobutylthio, tert- butylthio, pentylthio and hexylthio, especially methylthio, ethylthio, propylthio, isopropylthio, n-butylthio, sec-butylthio, isobutylthio, tert-butylthio, preferably methylthio. C1-C4Alkylthio is also linear or branched and has, for example, the meanings given above up to the corre¬ sponding number of carbon atoms. Phenyl or benzoyl radicals substituted by halogen, C1-C6alkyl, CrC6alkylthio or CrC6alkoxy are, for example, mono- to penta-substituted, for example mono-, di- or tri-substituted, especially di- or tri-substituted, on the phenyl ring. Preference is given, for example, to 2,4,6- trimethylbenzoyl, 2,6-dichlorobenzoyl, 2,6-dimethylbenzoyl and 2,6-dimethoxybenzoyl.

CrC4Alkylene and C2-C6alkylene are linear or branched alkylene, for example C2-C4alkylene, e.g. methylene, ethylene, propylene, isopropylene, n-butylene, sec-butylene, isobutylene, tert- butylene, pentylene or hexylene. Preference is given to CrC4alkylene, e.g. ethylene or butyl- ene, -CH-CH2- , —CH-(CH2).,- , — CH-(CH2)3- or -C(CHs)2-CH2- , and methylene CH3 CH3 CH3

and ethylene.

Phenylene-d-C^alkylene is phenylene that is substituted by CrC4alkylene at one position of the aromatic ring, whereas CrC4alkylene-phenylene-C1-C4alkylene is phenylene that is substituted by CrC4alkylene at two positions of the phenylene ring. The alkylene radicals are in each case linear or branched and have, for example, the meanings given above up to the

corresponding number of carbon atoms. Examples are

The alkylene groups may, however, also be situated at other positions of the phenylene ring, for example also in the 1,3-position.

Cycloalkylene is, for example, C3-C12- or Ca-Cs-cycloalkylene, for example cyclopropylene, cyclopentylene, cyclohexylene, cyclooctylene, cyclododecylene, especially cyclopentylene and cyclohexylene, preferably cyclohexylene. C3-C12Cycloalkylene also denotes, however, a

structural unit such as — (CxH2xH — j—(cjή2y) — , wherein x and y independently of each

other are 0-6 and the sum of x + y is < 6, or — (CxH2x)-^- γ— (CyH2y) — , wherein x and y

independently of each other are 0-7 and the sum of x+y is < 7. C2-C12Alkenyl radicals may be mono- or poly-unsaturated and linear or branched and are, for example, C2-C8-, C2-C6- or C2-C4-alkenyl. Examples are allyl, methallyl, 1,1-dimethylallyl, 1- butenyl, 2-butenyl, 1,3-pentadienyl, 1-hexenyl, 1-octenyl, decenyl or dodecenyl, especially allyl.

When R7 and R8 together are C2-C6alkylene, they form together with the carbon atom to which they are bonded a C3-C7cycloalkyl ring. C3-C7Cycloalkyl is, for example, cyclopropyl, cyclopentyl, cyclohexyl, cycloheptyl, especially cyclopentyl and cyclohexyl, preferably cyclo- hexyl.

R0RbC=CRa- is, for example, -CH=CH2 or -C(CH3)=CH2, preferably -CH=CH2.

Suitable monomers or/and oligomers that comprise at least one ethylenically unsaturated group and which may be present in the solution, emulsion or suspension according to b1) are, for example, those described below in the case of d1).

UV absorbers suitable as reactive substance b2) include compounds from the following classes: hydroxyphenyl-benzotriazoles, hydroxyphenyl-benzophenones, oxalic acid amides, triazines, oxalanilides, cyanoacrylates, salicylic acids and hydroxyphenylpyrimidines. Also especially suitable are UV absorbers comprising an ethylenically unsaturated group. As ethylenically unsaturated groups there come into consideration especially those which can be polymerised by free radical polymerisation; in addition to vinyl and vinylidene groups there are to be mentioned especially acrylate, methacrylate, allyl ether, styryl ether and vinyl ether groups. Examples of triazines having an unsaturated group are described in WO 99/55471. EP 722938 describes, for example, the preparation of benzotriazoles having unsaturated double bonds. US 4880859 also describes benzotriazoles and benzophenones having ethylenically unsaturated groups and also cinnamic acid derivatives. Further corre¬ sponding benzotriazoles are described in EP 488145, EP 747755, US 5334235 and Research Disclosure May 1991 Pos. 32592. Preference is given to the following compounds: HO

R16 , wherein

Ri5 to Ri7 independently of one another may be H, linear or branched alkyl groups, substi¬ tuted or unsubstituted aryl groups, or ethylenically unsaturated groups bonded directly or via spacer groups; and

i- 9C— fi CH-C.H3 -C-C=CH2

R,5 , wherein

Ri5 and Ri6 independently of one another may be H, linear or branched alkyl groups, or sub¬ stituted or unsubstituted aryl groups. Special preference is given to the following compounds:

?R,7 , wherein

R17 is -CH2CH2OCOCH=CH21 -CH2COOCH2CH=CH-phenyl, -CH2CH(OH)CH2OCOC(CH3)=CH2, -CH2CH=CH2, -CH2COO(CH2)7CH=CHC8Hi7j -OCH=CH2 or -CH-OCH=CH2; CH, C-N-O-C-C, SCH, , wherein Ri5 is H, CrCi2alkyl, C6-C10aryl and Ri6 is H,

halogen, CrCi2alkyl or C6-C10aryl; HO

< TU N /CH3 CH3 N — #. ,/-o-c—c—o—c-c^. c— c-o— c-c. / \, // H2 H2 ^CH2 H2 H2 ■XH2 HO -C=CH2

C=CH, H 2 HO OH -C=CH2 \ H 2 O /CH3 CH2 Il o-c-c— o— c- -CH H5 H,

ff OH O CH2 Ii Il O-(CH2)^-O-C-CH CH3 O-(CH2)J-O-C Il-C /^. CH,

O PH2 o— c-cH and

The following compounds are also preferred: α-cyano-β,β-diphenylacrylic acid ethyl ester or isooctyl ester, α-methoxycarbonylcinnamic acid methyl ester, α-cyano-β-methyl-p-methoxy- cinnamic acid methyl ester or butyl ester, α-methoxycarbonyl-p-methoxycinnamic acid methyl ester, N-(β-methoxycarbonyl-β-cyanovinyl)-2-methyl-indoline, N-(phthalimidomethyl)acryl- amide, vinylphenyl acetate, 9-vinylanthracene, phenylmethacrylate, 2-phenylethyl acrylate, 2- phenylethylmethacrylate, 4-(2-acryloxyethoxy)-2-hydroxybenzophenone, 3-allyl-4-hydroxy- acetophenone. It is known from many publications that UV absorbers combined with other substances (synergists) afford especially effective protection. Such synergists can also be used within the context of the invention. Examples of synergists are light stabilisers, free radical scavengers, peroxide decomposers etc.. Examples of synergists are compounds from the following classes: sterically hindered amines, amino ethers (>NOR-compounds), benzoxazines and/or thioethers. A number of compounds may be mentioned as examples: bis(2,2,6,6-tetramethylpiperidyl) sebacate, bis(2,2,6,6-tetramethylpiperidyl) succinate, bis(1 ,2,2,6,6-pentamethylpiperidyl) sebacate, n-butyl-3,5-di-tert-butyl-4- hydroxybenzylmalonic acid bis(1,2,2,6,6-pentamethylpiperidyl) ester, condensation product of 1-hydroxyethyl-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid, condensation product of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamin e and 4-tert- octylamino-2,6-dichloiO-1,3,5-s-triazine, tris(2J2,6)6-tetramethyl-4-piperidyl) nitrilotriacetate, tetrakis(2]2J6J6-tetramethyl-4-piperidyl)-1,2,3J4-butanetetr aoate, 1,1'-(1,2-ethanediyl)- bis(3,3,5J5-tetramethylpiperazinone)) 4-benzoyl-2,2,6,6-tetramethylpiperidine, 4-stearyloxy- 2,2,6,6-tetramethylpiperidine, bis(1,2,2,6,6-pentamethylpiperidyl)-2-n-butyl-2-(2-hydroxy-3 ,5- di-tert-butylbenzyl) malonate, 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decane-2,4- dione, bis(1-octyloxy-2,2,6,6-tetramethylpiperidyl) sebacate, bis(1-octyloxy-2,2,6,6-tetra- methylpiperidyl) succinate, condensation product of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)- hexamethylenediamine and 4-morpholino-2,6-dichloro-1,3)5-triazine, condensation product of 2-chloro-4J6-di(4-n-butylamino-2]2,6,6-tetramethylpiperidyl) -1,3J5-triazine and 1,2-bis(3- aminopropylamino)ethane, condensation product of 2-chloro-4,6-di(4-n-butylamino-1 ,2,2,6,6- pentamethylpiperidyl)-1,3,5-triazine and 1,2-bis(3-aminopropylamino)ethaneJ 8-acetyl-3- dodecyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decane-2,4-dione, 3-dodecyl-1-(2,2,6,6- tetramethyl-4-piperidyl)pyrrolidine-2,5-dione, 3-dodecyl-1-(1,2,2,6,6-pentamethyl-4-piperidyl)-

pyrrolidine-2,5-dione, cβHi7θ-N )AOCO(CH2)8COO-^~^ N-OC8H17 anc| reaction products of Λ — Λ H3C CH3 H3C CH3 N,N'-ethane-1,2-diylbis(1,3-propanediamine), cyclohexane, peroxidised 4-butylamino-2,2,6,6- tetramethylpiperidine and 2,4,6-trichloro-1 ,3,5-triazine.

Suitable free-radical-forming initiators according to b2) are, for example, those mentioned in b1), both those compounds having an ethylenically unsaturated group and those not having that group. Suitable monomeric or oligomeric ethylenically unsaturated compounds that may be present in the solution, emulsion or suspension according to b2) are, for example, those described hereinbelow in d1).

Suitable electron or H donors b3) are, for example, primary, secondary or tertiary amines, thiols or thioethers or mixtures thereof. In principle, all amines, thiols and thioethers that comprise at least one ethylenically unsatu¬ rated group are suitable for use in the process according to the invention. Preference is given to amines, especially secondary or tertiary amines. Preference is also given to aliphatic or cycloaliphatic amines which, in addition to the amine nitrogen, may con¬ tain further hetero atoms. Examples are derivatives of piperidine, morpholine or piperazine. The amines may also be oligomeric amines. Special preference is given to compounds of formulae Xa, Xb, Xc, Xd and Xe. R20-C-C-O-(CH2)P-N-R22 (Xa)1 ^N-(X5)C=C-C-OR24 (Xb)1

Ri-C-C-O-(CH2Jp-SR2, (Xc), Rn-S-(Xs)-C=C-C-OR2, (Xd), R20-C-C-N-R2, (χe), H wherein R20 is H or d-C4alkyl; preferably H or CH3; R2i and R22 independently of each other are CrC18alkyl or, in formulae Xa, Xb and Xe, form together with the nitrogen atom a 5- or 6- membered cycloaliphatic ring which may, in addition, be interrupted by a nitrogen or oxygen CH2O ii Il atom; or R21 in formula Xc has the additional meaning of a group R20-C-C-O-(CH2)- ; R23 is

C1-C18alkyl, phenyl, phenyl-C^Caalkyl or a group -C(O)-CrCi8alkyl, 'C(O)-(CH2)q-phenyl, wherein q is a number from O to 3; R24 is C1-C18alkyl, phenyl or phenyl-CrC3alkyl; X5 is a direct bond, a group -(CH2)P- or a branched C3-C18alkylene group; and p is a number from 1 to 12. Preferably, R2i and R22 are C1-C4BlKyI or form together with the nitrogen atom to which they are bonded a morpholine radical. Preferably, R23 is C1-C4alkyl or benzyl. R24 is preferably C1-C4alkyl and p is preferably from 1 to 4. The definition of the substituents in the various radicals is analogous to that given in b1). When R2i and R22 together with the nitrogen atom form a 5- or 6-membered cycloaliphatic ring which may, in addition, be interrupted by a nitrogen or oxygen atom, that ring may, for example, be cyclopentyl, cyclohexyl, pyrrolidine, morpholine, pyrazoline, pyrazolidone, imidazoline, imidazolidine, oxazolidine, oxazolidinone, piperidine, piperazine or piperazinone. The majority of the compounds of formulae Xa to Xe are known and are commercially avail¬ able or can be prepared by analogous processes. Vinyl ethers or styrenes containing amine or thio groups are also suitable compounds.

Examples are: Specific examples of suitable ethylenically unsaturated amines, thiols and thioethers are mentioned below. 2-N-morpholinoethyl acrylate, 2-N-morpholinoethyl methacrylate, N,N-diethylaminoethyl acrylate, N.N-dimethylaminoethyl acrylate, 3-(dimethylamino)propyl acrylate, 2-(diethyl- amino)ethyl methacrylate, 2-(dimethylamino)ethyl methacrylate, 3-(dimethylamino)neopentyl acrylate, 2-(tert-butylamino)ethyl methacrylate, 2-(diisopropylamino)ethyl methacrylate, 2- aminoethyl methacrylate hydrochloride, methyl-3-(dimethylamino)-2-(2,2-dimethylpropan- oyl)acrylate, ethyl-3-dimethylaminoacrylate, benzyl-2-(diphenylmethylaminomethyl) acrylate hydrobromide, 2-dimethylamino-1-benzamido-methyl acrylate, 3-(dimethylamino)propyl acrylate, 3-amino-3-(trifluoromethylphenylamino)ethyl acrylate hydrochloride, 2-((2-acetyl-3- oxo-1-butenyl)amino)-3-(dimethylamino)methyl acrylate, ethylthioethyl methacrylate, thiol- diethylene glycol diacrylate, 2-(methylthio)ethyl methacrylate and methyl-2-methylthioacry- late. Also suitable are dimethyl-bis(methylthio)methylene malonate, N-vinylpyrrolidone and N,N- diethyl-2-ethylvinyl ether. All of those compounds are known and commercially available. Suitable amines that can also be used in the context of the present invention are furthermore provided by a number of manufacturers under their trade names. Examples are mentioned below. UCB SA Ebecryl® P 115 and Ebecryl® 7100 by UCB. CN 371, CN 383, CN 384, CN 381, CN 386 by Cray Valley. Genomer® 5248, Genomer®5275, Genomer®5695, ACMO (acryl- oylmorpholine) by Rahn. Actilan® 705, 715, 725, 735, 745 by Akcros Chemicals. Ageflex® FH 1, FH 2, FU 1, FU 2, FU 4 by CPS Chemical Company. Photomer 4770, Photomer 4967, RCC 13-660, RCC 13-661 by Cognis. Laromer LR 8956 by BASF.

The following groups are to be understood as being a function-controlling group in accor¬ dance with the chemically active substances used in b4) of the process according to the invention: i) a hydrophilic or hydrophobic group for controlling hydrophilicity/hydrophobicity, ii) an acid, neutral or basic functional group for controlling acid/base properties, iii) a functional group having a high or low incremental refraction, for controlling refractive index, iv) a functional group having an effect on the growth of cells and/or organisms, for controlling biological properties, v) a functional group having an effect on combustibility, for controlling flame resistance properties, and/or vi) a functional group having an effect on electrical conductivity, for controlling antistatic properties.

There is preferably used as the hydrophilic group a polar group, such as an alcohol, ether, acid, ester, aldehyde, keto, sugar, phenol, urethane, acrylate, vinyl ether, epoxy, amide, acetal, ketal, anhydride, quaternised amino, imide, carbonate or nitro group, a salt of an acid, or a (poly)glycol unit. Especially good results are obtained when acrylic acid, acrylamide, acetoxystyrene, acrylic anhydride, acrylic succinimide., ally! glycidyl ether, allylmethoxy- phenol, polyethylene glycol (400) diacrylate, diethyl ene glycol diacrylate, diurethane dimethacrylate, divinyl glycol, ethylene glycol diglycidyl ether, glycidyl acrylate, glycol methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, N-(2-hydroxypropyl)methacrylamide, methacryloxyethyl glucoside, nitro- styrene, sulfoethyl methacrylate, the sodium salt of 3-sulfopropyl acrylate, 4-vinylbenzoic acid, vinylmethylsulfone, vinylphenyl acetate or vinyl urea is used as the hydrophilic group.

There is preferably used as the functional group controlling acid/base properties a carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid, phenol, amino acid or amino, pyridine, pyrimidine, piperidine, pyrrole or imidazole group. It is especially advantageous to use allylamine, 2-aminoethyl methacrylate, 4-vinylpyridine, vinylpyrrolidone, vinyl imidazole, morpholinoethyl acrylate, acrylic acid, 2-propene-1 -sulfonic acid, sorbic acid, cinnamic acid or maleic acid. To control the refractive index, a benzyl group, a partially or completely halogenated benzyl group, or a partially or completely halogenated alkane, alkene or alkyne group is preferably used, benzyl acrylate, 1H,1H,7H-dodecafluoroheptyl methacrylate, 1H,1H-heptafluorobutyl acrylate and trifluoroethyl acrylate having been found especially advantageous. As a group that controls biological properties it is possible to use a group having antifouling properties, such as copper(ll) methacrylate, dibutyltin maleate, tin(ll) methacrylate or zinc dimethacrylate. Another possibility for controlling the biological properties is to use a group that promotes growth of biological systems. Succinimide, glucoside and sugar groups have been found especially advantageous for that purpose, especially good results being obtained with N- acyloxysuccinimide or 2-methacryloxyethylglucoside. As a group that controls flame resistance properties, a completely or partially chlorinated or brominated alkane or nitrogen- or phosphorus-containing group is used. Special preference is given to phenyltribromomethylsulphone, 2,2,2-trichloro-1-[4-(1,1-dimethylethyl)phenyl]- ethanone, tribromoneopentyl methacrylate, bis(2-methacryloxyethyl) phosphate or monoacryloxyethyl phosphate. The antistatic properties can also be controlled by selecting a suitable functional group. Functional groups that are especially suitable for the purpose are tertiary amino, ethoxylated amino, alkanol amide, glycerol stearate, sorbitan or sulfonate groups, such as especially 2- diisopropylaminoethyl methacrylate, 3-dimethylaminoneopentyl acrylate or oleylbis(2-hydr- oxyethyl)amine, stearyl acrylate and/or vinyl stearate.

An activatable initiator incorporating at least one group that interacts with a subsequently applied coating to impart adhesion or reacts with groups contained therein in accordance with the chemically active substances used in b5) of the process according to the invention is to be understood as being, for example, a compound which is capable of specifically intro¬ ducing chemical functionalities to produce the reactive groups. Suitable activatable initiators are all compounds or mixtures of compounds that produce one or more free radicals (including in the form of intermediates) when heated and/or when irra¬ diated with electromagnetic waves. These include, in addition to compounds or combinations that are usually thermally activated, such as, for example, peroxides and hydroperoxides (also in combination with accelerators, such as amines and/or cobalt salts) and amino ethers (NOR compounds), photochemically activatable compounds (e.g. benzoins) or combinations of chromophores with coinitiators (e.g. benzophenone and tert-amines) or mixtures thereof. It is also possible to use sensitizers with coinitiators (e.g. thioxanthones with tert-amines) or chromophores (e.g. thioxanthones with amino ketones). Redox systems, such as a combina¬ tion of H2O2 with iron(ll) salts, can also be used. It is also possible to use electron-transfer pairs, such as dyes and borates and/or amines. It is possible to use as initiator a compound or a combination of compounds from the following classes: peroxides, peroxodicarbonates, persulfates, benzopinacols, dibenzyls, disulfides, azo compounds, redox systems, benzoins, benzil ketals, acetophenones, hydroxyalkylphenoπes, aminoalkylphenones, acylphosphine oxides, acylphosphine sulfides, acyloxyiminoketones, halogenated acetophenones, phenyl glyoxalates, benzophenones, oximes and oxime esters, thioxanthones, camphorquinones, ferrocenes, titanocenes, sulfonium salts, iodonium salts, diazonium salts, onium salts, bora- alkyls, borates, triazines, bisimidazoles, polysilanes and dyes, and corresponding coinitiators and/or sensitisers.

Preferred compounds are:1 dibenzoyl peroxide, benzoyl peroxide, dicumyl peroxide, cumyl hydroperoxide, diisopropyl peroxidicarbonate, methyl ethyl ketone peroxide, bis(4-tert-butyl- cyclohexyl) peroxidicarbonate, ammonium peroxomonosulfate, ammonium peroxodisulfate, dipotassium persulfate, disodium persulfate, N.N-azobisisobutyronitrile, 2,2'-azobis(2,4- dimethylpentanenitrile), 2,2'-azobis(2-methylpropanenitrile), 2,2'-azobis(2-methylbutane- nitrile), I.i'-azobisfcyanocyclohexane), tert-amyl peroxobenzoate, 2,2'-bis(tert-butylperoxy)- butane, 1,1' -bis(tert-butylperoxy)cyclohexane, 2J5-bis(tert-butylperoxy)-2,5-dimethylhexane, 2,5-bis(tert-butylperoxy)-2,5-dimethyl-3-hexyne, 1 , 1-bisCtert-butylperoxyJ-SAS-trimethylcycIo- hexane, tert-butyl hydroperoxide, tert-butyl peracetate, tert-butyl peroxide, tert-butyl peroxy- benzoate, tert-butyl peroxyisopropyl carbonate, cyclohexanone peroxide, lauroyl peroxide, 2,4-pentanedione peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexane, di-(2-tert-butyl- peroxyisopropyl)-benzene, cobalt octanoate, dicyclopentadienylchromium, peracetic acid, benzopinacol and dibenzyl derivatives, such as dimethyl-2,3-diphenylbutane, 3,4-dimethyl- 3,4-diphenylhexane, poly-1 ,4-diisopropylbenzene, N.N-dimethylcyclohexylammonium dibutyldithiocarbamate, N-tert-butyl-2-benzothiazole sulfenamide, benzothiazyl disulfide and tetrabenzylthiuram disulfide.

The irradiation in step c) is preferably carried out using radiation sources described herein¬ after (in d1)). The radiation dose used in step c) is, for example, from 1 to 100O mJ/cm2, such as approximately 1-800 mJ/cm2, or, for example, 1-500 mJ/cm2, for example from 5 to 300 mJ/cm2, preferably from 10 to 200 mJ/cm2.

The irradiation and, where appropriate, previous drying can be carried out, for example, in air or under inert gas conditions. Nitrogen, for example, comes into consideration as inert gas in this context, but other inert gases, such as, for example, CO2 or argon, helium etc. or mix¬ tures thereof are also suitable. Suitable systems and corresponding apparatus are familiar to the person skilled in the art and, for example, are also commercially available.

Following application of the chemically active substance, for example the photoinitiator, and subsequent exposure [Steps a)-c)], the workpiece can be stored or further processed directly, and a further coating d) can be applied. The latter step comprises, for example, the following: either d1), preferably, a radiation-curable coating containing ethylenically unsaturated bonds is applied by known techniques, or d2) a coating that dries/cures by different means, for example a printing ink or a surface coating, is applied. Coating can be carried out, for example, by pouring, immersion, spraying, brush application, knife applica¬ tion, roller application or spin-coating. The further layer d) may, however, also be, for example, d3) a metal layer.

Also of interest, therefore, is a process wherein the further coating d) is d1) a composition comprising at least one ethylenically unsaturated monomer or oligomer, which is cured by UV/VIS radiation or an electron beam; or d2) a printing ink or surface coating, or d3) a metal layer.

The unsaturated compounds of the radiation-curable composition d1) may contain one or more ethylenically unsaturated double bonds. They may be lower molecular weight (mono- meric) or higher molecular weight (oligomeric). Examples of monomers having a double bond are alkyl and hydroxyalkyl acrylates and methacrylates, e.g. methyl, ethyl, butyl, 2-ethylhexyl and 2-hydroxyethyl acrylate, isobornyl acrylate and methyl and ethyl methacrylate. Silicone acrylates are also of interest. Further examples are acrylonitrile, acrylamide, methacrylamide, N-substituted (meth)acrylamides, vinyl esters, such as vinyl acetate, vinyl ethers, such as isobutyl vinyl ether, styrene, alkyl- and halo-styrenes, N-vinylpyrrolidone, vinyl chloride and vinylidene chloride.

Examples of monomers having more than one double bond are ethylene glycol diacrylate, 1,6-hexanediol diacrylate, propylene glycol diacrylate, dipropylene glycol diacrylate, tripropyl- ene glycol diacrylate, neopentyl glycol diacrylate, hexamethylene glycol diacrylate and bis- phenol-A diacrylate, 4,4I-bis(2-acryloyloxyethoxy)diphenylpropane, trimethylolpropane tri- acrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, vinyl acrylate, divinylben- zene, divinyl succinate, diallyl phthalate, triallyl phosphate, trial IyI isocyanurate, tris(hydr- oxyethyl) isocyanurate triacrylate (Sartomer 368; from Cray Valley) and tris(2-acryloylethyl) isocyanurate,

It is also possible for acrylic esters of alkoxylated polyols, for example glycerol ethoxylate triacrylate, glycerol propoxylate triacrylate, trimethylolpropaneethoxylate triacrylate, trimethylolpropanepropoxylate triacrylate, pentaerythritol ethoxylate tetraacrylate, penta- erythritol propoxylatθ triacrylate, pentaerythritol propoxylate tetraacrylate, neopentyl glycol ethoxylate diacrylate or neopentyl glycol propoxylate diacrylate to be used in radiation- curable systems. The degree of alkoxylation of the polyols used may vary.

Examples of higher molecular weight (oligomeric) polyunsaturated compounds are acrylated epoxy resins, acrylated or vinyl-ether- or epoxy-group-containing polyesters, polyurethanes and polyethers. Further examples of unsaturated oligomers are unsaturated polyester resins, which are usually produced from maleic acid, phthalic acid and one or more diols and have molecular weights of about from 500 to 3000. In addition, it is also possible to use vinyl ether monomers and oligomers, and also maleate-terminated oligomers having polyester, polyurethane, polyether, polyvinyl ether and epoxide main chains. In particular, combinations of vinyl-ether-group-carrying oligomers and polymers, as described in WO 90/01512, are very suitable, but copolymers of monomers functionalised with maleic acid and vinyl ether also come into consideration. Such unsaturated oligomers can also be referred to as prepolymers.

Especially suitable examples are esters of ethylenically unsaturated carboxylic acids and polyols or polyepoxides, and polymers having ethylenically unsaturated groups in the chain or in side groups, e.g. unsaturated polyesters, polyamides and polyurethanes and copoly¬ mers thereof, alkyd resins, polybutadiene and butadiene copolymers, polyisoprene and iso- prene copolymers, polymers and copolymers having (meth)acrylic groups in side chains, and also mixtures of one or more such polymers.

Examples of unsaturated carboxylic acids are acrylic acid, methacrylic acid, crotonic acid, itaconic acid, cinnamic acid and unsaturated fatty acids such as linolenic acid or oleic acid. Acrylic and methacrylic acid are preferred. Suitable polyols are aromatic and especially aliphatic and cycloaliphatic polyols. Examples of aromatic polyols are hydroquinone, 4,4'-dihydroxydiphenyl, 2,2-di(4-hydroxyphenyl)propane, and novolaks and resols. Examples of polyepoxides are those based on the said polyols, especially the aromatic polyols and epichlorohydrin. Also suitable as polyols are polymers and copolymers that contain hydroxyl groups in the polymer chain or in side groups, e.g. polyvinyl alcohol and copolymers thereof or polymethacrylic acid hydroxyalkyl esters or copolymers thereof. Further suitable polyols are oligoesters having hydroxyl terminal groups. Examples of aliphatic and cycloaliphatic polyols include alkylenediols having preferably from 2 to 12 carbon atoms, such as ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1,4- butanediol, pentanediol, hexanediol, octanediol, dodecanediol, diethylene glycol, triethylene glycol, polyethylene glycols having molecular weights of preferably from 200 to 1500, 1,3- cyclopentanediol, 1,2-, 1,3- or 1,4-cyclohexanediol, 1,4-dihydroxymethylcyclohexane, glyc¬ erol, tris(β-hydroxyethyl)amine, trimethylolethane, trimethylolpropane, pentaerythritol, di- pentaerythritol and sorbitol.

The polyols may have been partially or completely esterifled by one or by different unsaturated carboxylic acid(s), it being possible for the free hyd roxyl groups in partial esters to have been modified, for example etherified, or esterified by other carboxylic acids.

Examples of esters are: trimethylolpropane triacrylate, trimethylolethane triacrylate, triinethylolpropane trimethacryl- ate, trimethylolethane trimethacrylate, tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol diacrylate, dipentaerythritol tri¬ acrylate, dipentaerythritol tetraacrylate, dipentaerythritol pemtaacrylate, dipentaerythritol hexaacrylate, tripentaerythritol octaacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dipentaerythritol dimethacrylate, dipentaerythiritol tetramethacrylate, tri¬ pentaerythritol octamethacrylate, pentaerythritol diitaconate, dipentaerythritol trisitaconate, dipentaerythritol pentaitaconate, dipentaerythritol hexaitaconate^ ethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diitaconate, sorbitol triacrylate, sorbitol tetraacrylate, pentaerythritol-modified triacrylate, sorbitol tetramethacryl¬ ate, sorbitol pentaacrylate, sorbitol hexaacrylate, oligoester aorylates and methacrylates, glycerol di- and tri-acrylate, 1 ,4-cyclohexane diacrylate, bisacrylates and bismethacrylates of polyethylene glycol having a molecular weight of from 200 to 150O, and mixtures thereof. Also suitable as constituents are the amides of identical or different unsaturated carboxylic acids and aromatic, cycloaliphatic and aliphatic polyamines hawing preferably from 2 to 6, especially from 2 to 4, amino groups. Examples of such polyamines are ethylenediamine, 1,2- or 1,3-propylenediamine, 1,2-, 1,3- or 1 ,4-butylenediamine, 1,5-pentylenediamine, 1,6- hexylenediamine, octylenediamine, dodecylenediamine, 1,4-diarnino-cyclohexane, isophor- onediamine, phenylenediamine, bisphenylenediamine, di-β-aminoethyl ether, diethylenetri- amine, triethylenetetramine and di(β-aminoethoxy)- and di(β-aminopropoxy)-θthane. Further suitable polyamines are polymers and copolymers which may have additional amino groups in the side chain and oligoamides having amino terminal groups. .Examples of such unsaturated amides are: methylene bisacrylamide, 1 ,6-hexamethylene bisacrylamide, diethylenetriamine trismethacrylamide, bis(methacrylamidopropoxy)ethane, β-methacryl- amidoethyl methacrylate and N-[(β-hydroxyethoxy)ethyl]-acrylamide.

Suitable unsaturated polyesters and polyamides are derived, for example, from maleic acid and diols or diamines. The maleic acid may have been partially replaced by other dicarbox- ylic acids. They may be used together with ethylenically unsaturated comonomers, e.g. styrene. The polyesters and polyamides may also be derived from dicarboxylic acids and ethylenically unsaturated diols or diamines, especially from those having longer chains of e.g. from 6 to 20 carbon atoms. Examples of polyurethanes are those composed of saturated diisocyanates and unsaturated diols or unsaturated diisocyanates and saturated diols.

Polybutadiene and polyisoprene and copolymers thereof are known. Suitable comonomers include, for example, olefins, such as ethylene, propene, butene, hexene, (meth)acrylates, acrylonitrile, styrene and vinyl chloride. Polymers having (meth)acrylate groups in the side chain are likewise known. Examples are reaction products of novolak-based epoxy resins with (meth)acrylic acid; homo- or co-polymers of vinyl alcohol or hydroxyalkyl derivatives thereof that have been esterified with (meth)acrylic acid; and homo- and co-polymers of (meth)acrylates that have been esterified with hydroxyalkyl (meth)acrylates.

In the context of this Application, the term (meth)acrylate includes both the acrylate and the methacrylate. An acrylate or methacrylate compound is especially used as the mono- or poly-ethylenically unsaturated compound. Very special preference is given to polyunsaturated acrylate compounds, such as have already been mentioned above. Special preference is given to a process wherein at least one of the ethylenically unsaturated monomers or oligomers of the radiation-curable composition is a mono-, di-, tri- or tetra- functional acrylate or methacrylate. Preferably, in addition to containing at least one ethylenically unsaturated monomer or oligomer, the composition comprises at least one further photoinitiator or coinitiator for curing with UV/VIS radiation.

The invention also relates, therefore, to a process wherein, in process step d1), a photo- polymerisable composition comprising at least one ethylenically unsaturated monomer or/and oligomer and at least one photoinitiator and/or coinitiator is applied to the pretreated substrate and cured by means of UV/VIS radiation.

In the context of the present invention, UV/VIS radiation is to be understood as being electromagnetic radiation in a wavelength range of from 150 nm to 800 nm. Preference is given to the range from 200 nm to 500 nm. Suitable radiation sources are known to the person skilled in the art and are commercially available. The light-sensitivity of the compositions according to process step d1) generally ranges from about 150 nm to about 600 nm (UV region). A large number of the most varied kinds of light source may be used. Both point sources and planiform radiators (lamp arrays) are suitable. Examples are: carbon arc lamps, xenon arc lamps, medium-pressure, super-high-pressure, high-pressure and low-pressure mercury radiators doped, where appropriate, with metal halides (metal halide lamps), microwave-excited metal vapour lamps, excimer lamps, super- actinic fluorescent tubes, fluorescent lamps, argon incandescent lamps, flash lamps, photographic floodlight lamps, light-emitting diodes (LED), electron beams and X-rays. The distance between the lamp and the substrate to be exposed may vary according to the intended use and the type and strength of the lamp and may be, for example, from 2 cm to 150 cm. Also suitable are laser light sources, for example excimer lasers, such as Krypton-F lasers for irradiation at 248 nm. Lasers in the visible range may also be used. Using that method, it is possible to produce printed circuits in the electronics industry, lithographic offset printing plates or intaglio printing plates, and photographic image recording materials.

The above description of suitable radiation sources relates both to the irradiation step c) (fixing of the photoinitiator) in the process according to the invention and to the procedure of process step d1) (curing of the photocurable composition). Curing of the composition applied in process step d1) or d2) may, in addition, also be carried out using daylight or daylight-equivalent light sources. Advantageously, the dose of radiation used in process step c) is, for example, from 1 to 1000 mJ/cm2, such as 1-800 mJ/cm2, or, for example, 1-500 mJ/cm2, e.g. from 5 to 300 mJ/cm2, preferably from 10 to 200 mJ/cm2.

As the photoinitiator in the radiation-curable compositions according to process step d1) it is possible to use either compounds of formula I or Ia or any other initiators and initiator systems known from the prior art. Photoinitiators that do not have unsaturated groups are preferably used in those compositions.

Typical examples are mentioned below, which can either be used individually or in the form of mixtures with one another. For example, benzophenones, benzophenone derivatives, acetophenone, acetophenone derivatives, such as, for example, oc-hydroxycycloalkyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propanone or 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl- propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, dialkoxyacetophenone, α-hydroxy- or α-aminoacetophenone, such as e.g. (4-methylthiobenzoyl)-1-methyl-1-morpholino-ethane, (4-morpholino-benzoyl)-1-benzyl-1-dimethylamino-propane, (4-methylthiobenzoyl)-1-methyl- 1-morpholino-ethane, (4-morpholino-benzoyl)-1-(4-methyl-benzyl)-1-dimethylamino-p ropane, 4-aroyl-1,3-dioxolanes, benzoin alkyl ethers and benzil ketals, such as e.g. benzil dimethyl ketal, phenylglyoxalates and derivatives thereof, dimeric phenylglyoxalates, such as e.g. [5,5'-oxodi(ethyleneoxydicarbonylphenyl)], monoacylphosphine oxides, such as e.g. (2,4,6- trimethylbenzoyl)-phenyl-phosphine oxide, bisacylphosphine oxides, such as e.g. bis(2,6-di- methoxybenzoyl)-(2,4,4-trimethyl-pent-1-yl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)- phenyl-phosphine oxide or bis(2,4,6-trimethylbenzoyl)-(2,4-dipentyloxyphenyl)phosphine oxide, trisacylphosphine oxides, oxime esters, e.g. 1,2-octanedione-1-[4-(phenylthio)phenyl]- 2-(O-benzoyloxime) and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyl oxime)- ethanone, ferrocenium compounds or trtanocenes, such as, for example, dicyclopentadienyl- bis(2,6-difluoro-3-pyrτolo-phenyl)-titanium and borate salts. As coinitiators there come into consideration, for example, sensitisers which shift or broaden the spectral sensitivity and thus bring about an acceleration of the photopolymerisation. They are especially aromatic carbonyl compounds, for example benzophenone, thioxanthone, especially isopropyl thioxanthone, anthraquinone and 3-acylcoumarin derivatives, terphenyls, styryl ketones, and also 3-(aroylmethylene)-thiazolines, camphorquinone, and also eosine, rhodamine and erythrosine dyes. Amines, for example, can also be regarded as photosensitisers when the photoinitiator layer grafted on according to the invention consists of a benzophenone or benzophenone deriva¬ tive. Especially suitable compounds are disclosed, for example, in WO 03/064061, page 27, paragraph 2 to page 28, paragraph 4.

In addition to those additives, it is also possible for the radiation-curable composition to comprise further additives, especially light stabilisers. The nature and amount of such additional additives are governed by the intended use of the coating in question and will be familiar to the person skilled in the art.

The compositions may also be pigmented when suitable photoinitiators are chosen, it being possible for coloured pigments and white pigments to be used.

The photocurable compositions (process step d1)) can be applied in layer thicknesses of from about 0.1 μm to about 1000 μm, preferably from about 1 μm to 100 μm. In the range of low layer thicknesses of < 50 μm, pigmented compositions, for example, are also referred to as printing inks.

As light stabilisers it is possible to add UV absorbers, e.g. those of the hydroxyphenyl- benzotriazole, hydroxyphenylbenzophenone, oxalic acid amide or hydroxyphenyl-s-triazine type. Such compounds can be used singly or in the form of mixtures, with or without the use of sterically hindered amines (HALS). In addition to the light stabilisers mentioned above, other stabilisers, such as phosphites or phosphonites, for example, are also suitable.

Especially suitable compounds have already been described above in connection with component b2) or are to be found, for example, in WO 03/064061, page 29, paragraph 2 to page 31, paragraph 3.

Depending upon the field of use, it is also possible to use additives that are customary in the art, e.g. antistatics, flow improvers and adhesion promoters.

The compositions applied in process step d), for example d1) or d2), are, for example, pigmented or non-pigmented surface coatings, inks, ink-jet inks; printing inks, for example screen printing inks, offset printing inks, flexographic printing inks; or overprint varnishes; or primers; or printing plates, offset printing plates; powder coatings, adhesives or repair coatings, repair varnishes or repair putty compositions.

The compositions used in process step d1) need not necessarily comprise a photoinitiator - for example they may be customary electron-beam-curable compositions (without photo¬ initiator) known to the person skilled in the art.

The substrates pretreated in accordance with the process of the invention (steps a)-c)) may be coated with conventional photocurable compositions and cured by U VVVIS radiation or an electron beam in a further step d1) or, alternatively, d2) provided with a conventional coating that is dried, for example, in air or thermally. Drying may also be effected, for example, by absorption, e.g. penetration into the substrate.

The coating used in process step d2) is preferably a printing ink. Such printing inks are known to the person skilled in the art, are used widely in the art and are described in the literature. They are, for example, pigmented printing inks and printing inks coloured with dyes. A printing ink is, for example, a liquid or paste-form dispersion that comprises colorants (pigments or dyes), binders and also optionally solvents and/or optionally water and additives. In a liquid printing ink, the binder and, if applicable, the additives are generally dissolved in a solvent. Customary viscosities in the Brookfield viscometer are, for example, from 20 to 5000 mPa-s, for example from 20 to 1000 mPa-s, for liquid printing inks. For paste-form printing inks, the values range, for example, from 1 to 100 Pa s, preferably from 5 to 50 Pa-s. The person skilled in the art will be familiar with the ingredients and compositions of printing inks. Suitable pigments, like the printing ink formulations customary in the art, are generally known and widely described. Printing inks comprise pigments advantageously in a concentration of, for example, from 0.01 to 40 % by weight, preferably from 1 to 25 % by weight, especially from 5 to 10 % by weight, based on the total weight of the printing ink. The printing inks can be used, for example, for intaglio printing, flexographic printing, screen printing, offset printing, lithography or continuous or dropwise ink-jet printing on material pre¬ treated in accordance with the process of the invention using generally known formulations, for example in publishing, packaging or shipping, in logistics, in advertising, in security printing or in the field of office equipment. Suitable printing inks are both solvent-based printing inks and water-based printing inks. Of interest are, for example,' printing inks based on aqueous acrylates. Such inks are to be understood as including polymers or copolymers that are obtained by polymerisation of at 0 o ,■ least one monomer containing a group — -c-c-o— or --C-C-Nx and that are dissolved CH2 CH2 in water or a water-containing organic solvent. Suitable organic solvents are water-miscible solvents customarily used by the person skilled in the art, for example alcohols, such as methanol, ethanol and isomers of propanol, butanol and pentanol, ethylene glycol and ethers thereof, such as ethylene glycol methyl ether and ethylene glycol ethyl ether, and ketones, such as acetone, ethyl methyl ketone or cyclo, for example isopropanol. Water and alcohols are preferred. Suitable printing inks comprise, for example, as binder primarily an acrylate polymer or copolymer and the solvent is selected, for example, from the group consisting of water, CrC5alcohols, ethylene glycol, 2-(CrC5alkoxy)-ethanol, acetone, methyl ethyl ketone and any mixtures thereof. In addition to the binder, the printing inks may, where appropriate, also comprise customary additives known to the person skilled in the art in customary concentrations. For intaglio or flexographic printing, a printing ink is usually prepared by dilution of a printing ink concentrate and can then be used in accordance with methods known perse. The printing inks may, for example, also comprise alkyd systems that dry oxidatively. The printing inks are dried in a known manner customary in the art, optionally with heating of the coating.

A suitable aqueous printing ink composition comprises, for example, a pigment or a com¬ bination of pigments, a dispersant and a binder. Dispersants that come into consideration include, for example, customary dispersants, such as water-soluble dispersants based on one or more arylsulfonic acid/formaldehyde condensation products or on one or more water-soluble oxalkylated phenols, non-ionic dispersants or polymeric acids. The arylsulfonic acid/formaldehyde condensation products are obtainable, for example, by sulfonation of aromatic compounds, such as naphthalene itself or naphthalene-containing mixtures, and subsequent condensation of the resulting arylsulfonic acids with formaldehyde. Such dispersants are known and are described, for example, in US 5186846 and DE 19727767. Suitable oxalkylated phenols are likewise known and are described, for example, in US 4218218 and DE 19727767. Suitable non-ionic dispersants are, for example, ■ alkylene oxide adducts, polymerisation products of vinylpyrrolidone, vinyl acetate or vinyl alcohol and co- or ter-polymers of vinyl pyrrolidone with vinyl acetate and/or vinyl alcohol. It is also possible, for example, to use polymeric acids which act both as dispersants and as binders.

Examples of suitable binder components that may be mentioned include acrylate-group- containing, vinyl-group-containing and/or epoxy-group-containing monomers, prepolymers and polymers and mixtures thereof. Further examples are melamine acrylates and silicone acrylates. The acrylate compounds may also be non-ionically modified (e.g. provided with amino groups) or ionically modified (e.g. provided with acid groups or ammonium groups) and used in the form of aqueous dispersions or emulsions (e.g. EP 704469, EP 12339). Furthermore, in order to obtain the desired viscosity, the solventless acrylate polymers can be mixed with so-called reactive diluents, for example vinyl-group-containing monomers. Further suitable binder components are epoxy-group-containing compounds. The printing ink compositions may also comprise as additional component, for example, an agent having a water-retaining action (humectant), e.g. polyhydric alcohols, polyalkylene glycols, which renders the compositions especially suitable for ink-jet printing. It will be understood that the printing inks may comprise further auxiliaries, such as are customary especially for (aqueous) ink-jet inks and in the printing and coating industries, for example preservatives (such as glutardialdehyde and/or tetramethylolacetyleneurea, anti-oxidants, degassers/defoamers, viscosity regulators, flow improvers, anti-settling agents, gloss improvers, lubricants, adhesion promoters, anti-skin agents, matting agents, emulsifiers, stabilisers, hydrophobic agents, light stabilisers, handle improvers and anti¬ statics. When such agents are present in the compositions, their total amount is generally < 1 % by weight, based on the weight of the preparation.

Printing inks suitable in process step d2) also include, for example, those comprising a dye (with a total content of dyes of e.g. from 1 to 35 % by weight, based on the total weight of the ink). Dyes suitable for colouring such printing inks are known to the person skilled in the art and are widely available commercially, e.g. from Ciba Spezialitatenchemie AG, Basel. Such printing inks may comprise organic solvents, e.g. water-miscible organic solvents, for example CrC4alcohols, amides, ketones or ketone alcohols, ethers, nitrogen-containing heterocyclic compounds, polyalkylene glycols, C2-C6alkylene glycols and thioglycols, further polyols, e.g. glycerol and CrC4alkyl ethers of polyhydric alcohols, usually in an amount of from 2 to 30 % by weight, based on the total weight of the printing ink. The printing inks may also, for example, comprise solubilisers, e.g. ε-caprolactam. The printing inks may, inter alia for the purpose of adjusting the viscosity, comprise thicken¬ ers of natural or synthetic origin. Examples of thickeners include commercially available alginate thickeners, starch ethers or locust bean flour ethers. The printing inks comprise such thickeners e.g. in an amount of from 0.01 to 2 % by weight, based on the total weight of the printing ink. It is also possible for the printing inks to comprise buffer substances, for example borax, borates, phosphates, polyphosphates or citrates, in amounts of e.g. from 0.1 to 3 % by weight, in order to establish a pH value of e.g. from 4 to 9, especially from 5 to 8.5. As further additives, such printing inks may comprise surfactants or humectants. Surfactants that come into consideration include commercially available anionic and non-ionic surfact¬ ants. Humectants that come into consideration include, for example, urea or a mixture of sodium lactate (advantageously in the form of a 50 to 60 % aqueous solution) and glycerol and/or propylene glycol in amounts of e.g. from 0.1 to 30 % by weight, especially from 2 to 30 % by weight, in the printing inks. Furthermore, the printing inks may also comprise customary additives, for example foam- reducing agents or especially substances that inhibit the growth of fungi and/or bacteria. Such additives are usually used in amounts of from 0.01 to 1 % by weight, based on the total weight of the printing ink. The printing inks may also be prepared in customary manner by mixing the individual components together, for example in the desired amount of water. As already mentioned, depending upon the nature of the use, it may be necessary for e.g. the viscosity or other physical properties of the printing ink, especially those properties which influence the affinity of the printing ink for the substrate in question, to be adapted accord¬ ingly.

The printing inks are also suitable, for example, for use in recording systems of the kind in which a printing ink is expressed from a small opening in the form of droplets which are directed towards a substrate on which an image is formed. Suitable substrates are, for example, textile fibre materials, paper, plastics or aluminium foils pretreated by the process according to the invention. Suitable recording systems are e.g. commercially available ink-jet printers. Preference is given to printing processes in which aqueous printing inks are used.

As the coating d3) which can be applied to the substrate pretreated in accordance with steps a)-c) there come into consideration, for example, metals, semi-metals or metal oxides deposited from the gas phase.

Preferably, during deposition of the metal in step d3), irradiation using electromagnetic waves is carried out, either while the metal, semi-metal or metal oxide is being deposited from the gas phase or after that process.

Examples of suitable metals, semi-metals and metal oxides that can be applied to the substrate pretreated in accordance with the process of the invention steps a)-c) are zinc, copper, nickel, gold, silver, platinum, palladium, chromium, molybdenum, aluminium, iron, titanium. Preference is given to gold, silver, chromium, molybdenum, aluminium and copper, especially aluminium and copper. Also of interest are, for example, semi-metals and metal oxides such as aluminium oxide, chromium oxide, iron oxide, copper oxide and silicon oxide. Gold, silver, chromium, molybdenum, aluminium and copper are preferred. The metals, semi-metals or metal oxides are vaporised and are deposited under vacuum conditions on the substrate provided with the photoinitiator layer. This deposition may, as already mentioned, be carried out while performing irradiation with electromagnetic radiation. ■Alternatively, it is possible to carry out irradiation after the deposition of the metal. The temperatures for the deposition step depend upon the metal used and are, for example, especially in a range of from 300 to 20000C, preferably in the range of from 800 to 18000C.

The UV radiation during the deposition step may, for example, be produced by an anodic arc whereas, for UV irradiation after the deposition, the lamps described hereinbefore are suitable.

The metal-coated substrates may be used, for example, as diffusion-inhibiting layers or as electromagnetic shields or they are used as decorative elements, for decorative foils, or for foils used for packaging, e.g. for food packaging. The process according to the invention can be carried out within a wide pressure range, the discharge characteristics shifting as the pressure increases from a pure low-temperature plasma towards a corona discharge and finally changing into a pure corona discharge at an atmospheric pressure of about 1000-1100 mbar.

The process is preferably carried out at a process pressure of from 10"6 mbar up to atmos¬ pheric pressure (1013 mbar), especially in the range of from 10"4 to 10'2 mbar as a plasma process and at atmospheric pressure as a corona process. The flame treatment is usually carried out at atmospheric pressure.

The process is preferably carried out using as the carrier gas an inert gas or a mixture of an inert gas with a reactive gas.

When a corona discharge is used, air, CO2, nitrogen and/or noble gases are preferably used as the gas.

It is especially preferable to use air, H2, CO2, He, Ar, Kr, Xe, N2, O2 or H2O on its own or in the form of a mixture.

The photoinitiator layer deposited preferably has a thickness ranging, for example, from a monomolecular layer up to 100 nm, e.g. from 5 to 100 nm, or from 5 to 50 nm, e.g. 5-10 nm, preferably from 5 nm to 100 nm.

The plasma treatment or corona treatment of the inorganic or organic substrate a) preferably takes place for from 1 ms to 300 s, especially from 10 ms to 200 s.

In principle, it is advantageous to apply the photoinitiator as quickly as possible after the plasma-, corona- or flame-pretreatment, but for many purposes it may also be acceptable to carry out reaction step b) after a time delay. It is preferable, however, to carry out process step b) immediately after process step a) or within 24 hours after process step a). Also of interest is a process wherein process step c) is carried out immediately after process step b) or within 24 hours after process step b). The pretreated and photoinitiator-coated substrate can be subjected to process step d) immediately after coating and drying in accordance with process steps a), b) and c) or it can be stored in the pretreated form.

The chemically active substance, for example the photoinitiator in the case of b1), or where applicable the mixture of a plurality of chemically active substances (photoinitiators) and/or coinitiators, is applied to the corona-, plasma- or flame-pretreated substrate, for example, in pure form, that is to say without further additives, when the substances concerned are liquid, or alternatively is applied in combination with a monomer or oligomer, or dissolved in a solvent. The initiator, or the initiator mixture, can also, for example, be dispersed, suspended or emulsified in water, a dispersant being added as necessary. Of course, it is also possible to use any mixture of the above-mentioned components chemically active substance b), e.g. photoinitiator, monomer, oligomer, solvent and water.

Suitable dispersants, e.g. any surface-active compounds, preferably anionic and non-ionic surfactants, and also polymeric dispersants, are usually known to the person skilled in the art and are described, for example, in US 4965294 and US 5168087. Suitable solvents are in principle any substances in which component b), e.g. the photo¬ initiator or the photoinitiators, can be converted into a state suitable for application, whether in the form of a solution or in the form of a suspension or emulsion. Suitable solvents are, for example, alcohols, such as ethanol, propanol, isopropanol, butanol, ethylene glycol etc., ketones, such as acetone; methyl ethyl ketone, acetonitrile, aromatic hydrocarbons, such as toluene and xylene, esters and aldehydes, such as ethyl acetate, ethyl formate, aliphatic hydrocarbons, e.g. petroleum ether, pentane, hexane, cyclohexane, halogenated hydro¬ carbons, such as dichloromethane or chloroform, or alternatively oils, natural oils, castor oil, vegetable oil etc., and also synthetic oils. This description is by no means exhaustive and is given merely by way of example. Alcohols, water and esters are preferred. Suitable monomers and oligomers are, for example, those described above in connection with the photocurable composition.

Also of interest, therefore, is a process wherein the photoinitiators or mixtures thereof with monomers or oligomers in combination with one or more liquids (such as solvents or water) are used in the form of solutions, suspensions and emulsions. After the plasma-, corona- or flame-pretreatment, it is therefore possible in process step b1) to apply to the pretreated substrate, for example, 0.1-15 %, e.g. 0.1-5 %, of a photoinitiator having an unsaturated group or, for example, 0.1-15 %, e.g. 0.1-5 %, of a photoinitiator, for example not having an unsaturated group, and, for example, 0.5-10 % of a monomer, such as an acrylate, methacrylate, vinyl ether etc..

The application of the substances in step b), for example the photoinitiators, mixtures thereof with one another or with monomers or oligomers, is carried out, as described above, by spraying in the form of an aerosol. In the case of mixtures of photoinitiators with one another and with coinitiators and sensitisers, all possible mixing ratios can be used.

When the chemically active substances, e.g. the photoinitiators, are applied as mixtures with monomers or/and solvents or/and water in the form of liquids, solutions, emulsions or suspensions, they are used, for example, in concentrations of up to 20 %, e.g. from 0.01 to 20 %, or 0.01-10 %, e.g.0.1-20 %, or 0.5-10 %, based on the solution being applied.

The liquids comprising the photoinitiator may, in addition, contain e.g. further substances, such as defoamers, emulsifiers, surfactants, antifouling agents, wetting agents and other additives customarily used in the industry, especially the coating and paint industries.

Many possible methods of drying coatings are known and they can all be used in the claimed process. For example, it is possible to use hot gases, IR radiators, microwave and radio frequency radiators, ovens and heated rollers. Drying can also be effected, for example, by absorption, e.g. penetration into the substrate. This relates especially to the drying in process step c), but is also applicable to the drying carried out in process step d), especially d2). Drying can take place, for example, at temperatures of from 00C to 3000C, for example from 200C to 200°C. The irradiation of the coating in order to fix the photoinitiator in process step c) (and also to cure the formulation in process step d), especially d1)) can be carried out, as already men¬ tioned above, using any sources that emit electromagnetic waves of wavelengths that can be absorbed by the photoinitiators used. Such sources are generally radiation sources that emit radiation in the range from 200 nm to 700 nm. The use of electron beams is also a possibility. In addition to customary radiators and lamps, it is also possible to use lasers and LEDs (Light Emitting Diodes). The whole area of the coating or parts thereof may be irradiated. Partial irradiation is of advantage when only certain regions are to be rendered adherent. Suitable radiation sources are, for example, those already described above.

The drying and/or irradiation can be carried out under air or under inert gas. Nitrogen gas comes into consideration as inert gas, but other inert gases, such as CO2 or argon, helium etc. or mixtures thereof, can also be used. Suitable systems and apparatus are known to the person skilled in the art and are commercially available.

The invention further relates to the use of photoinitiators and photoinitiator systems in the process according to the invention.

The invention also relates to strongly adherent coatings obtainable in accordance with the process described above.

Strongly adherent coatings of that kind are important not only as protective layers or coverings, which may additionally be pigmented, but also for image-forming coatings, for example in resist and printing plate technology. In the case of image-forming processes, the irradiation can be effected through a mask or by writing using moving laser beams (Laser Direct Imaging - LDI). Such partial irradiation can be followed by a development or washing step in which portions of the applied coating are removed by means of solvents and/or water or mechanically. When the process according to the invention is used in the production of image-forming coatings (imaging), for example for the production of printing plates or electronic printed circuit boards, the image-forming step can be carried out either in process step c) or in process step d). In step d), depending upon the coating formulation used, the image-forming step may be a crosslinking reaction or alternatively a reaction in which the solubility of the formulation is altered.

The invention therefore relates also to a process wherein portions of the photoinitiators, or mixtures thereof with monomers and/or oligomers, applied in process step b) that have not been crosslinked after irradiation in process step c) are removed by treatment with a solvent and/or water and/or mechanically, and to a process wherein after irradiation in process step d1) portions of the coating are removed by treatment with a solvent and/or water and/or mechanically.

It is possible for image-forming processes to be used either in one of the two process steps c) and d1) or in both of steps c) and d1) in succession.

The Examples which follow illustrate the invention in more detail, without any limitation thereof to the Examples being intended. As in the remainder of the description and in the claims, parts and percentages relate to weight, unless otherwise indicated.

Example 1 A biaxially oriented polypropylene film (thickness 15 μm, Trespaphan) is corona-treated in air four times using a ceramic electrode (manual corona station type CEE 42-0-1 MD, width 330 mm, produced by SOFTAL) placed at a distance of approx. 1-2 mm, at an output of 600 W and at a treatment rate of 10 cm/s. O A~Λ 9 9H3 A 1 % ethanolic solution of photoinitiator A ∏ C=C-C-O-C-CΌ— v y— C-C-OH is applied 2 H H2 H2 \=/ I^

to the treated side of the film using a spray device in the form of an aerosol. After drying, the film is irradiated using a UV processor (Fusion Systems) with a microwave-excited mercury lamp with an output of 120 W/cm at a belt speed of 30 m/min . A radiation-curable printing ink composition of the following composition is applied to the substrate pretreated in that manner: 18.3 parts Ebecryl 1608 (bisphenol A epoxy acrylate, dissolved in 20 % OTA 480, an oligomeric triacrylate, UCB) 18.3 parts Ebecryl 657 (polyester tetraacrylate, UCB), 20.0 parts Ebecryl 220 (hexa-functional aromatic urethane acrylate, UCB), 20.9 parts Ebecryl 150 (bisphenol A derivative diacrylate oligomer, UCB), 22.5 parts lrgalit blue GLO (copper phthalocvanin (3), Ciba Specialty Chemicals) 100.0 3 % 2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-but anone (IRGACURE™ 369, Ciba Specialty Chemicals) are incorporated into that formulation. Curing of the prints is carried out in an IST UV exposure apparatus under a medium- pressure mercury lamp at a dose rate of 80 W/cm. A coating exhibiting good adhesion is obtained. Example 2 A plasma treatment is carried out in a plasma reactor at 13.56 MHz and at a variable output of from 10 to 100 W. A polyethylene film (PE film) is exposed to an argon/oxygen plasma (gas flow rates: argon 10 seem, oxygen 2.5 seem) at an output of 20 W for 1 second at room temperature and under a pressure of 5 Pa. Ventilation is then carried out and the sample is coated with the following formulation using a spray device: 1 % photoinitiator P38, a copolymerisable benzophenone produced by UCB; 0.2 % bis(2I4,6-trimethylbenzoyl)-phenyl-phosphine oxide, IRGACURE 819 produced by Ciba Specialty Chemicals, Switzerland; 1 % tris(hydroxyethyl)-isocyanurate-triacrylate, Sartomer 368 produced by Cray Valley, and isopropanol. After drying, the sample is irradiated with an 80 W/cm mercury lamp at a belt speed of 50 m/min. After application of the photoinitiator layer, a copper layer is deposited, in the same reactor, using an anodic arc process (VALICO process) under a pressure of 2x10"4 mbar. The crucible temperature is 1500-16000C. In approx. 1 minute, a layer of 1 μm thickness has been deposited. The copper layer cannot be detached by an adhesive tape.