Photopolymerisable composition and recording material produced therefrom.

The invention relates to a photopolymerizable mixture which contains a polymeric binder, a polymerizable compound, in particular an acrylic or alkacrylic acid ester, and a photoinitiator combination.

Photopolymerizable mixtures which contain certain combinations of photoinitiators and activators, for example initiators containing carbonyl groups and tertiary amines, are known to increase sensitivity to light. Such synergistic mixtures are described, for example, in US Pat. Nos. 3,759,807, 4,054,682 and 4,071,424. A disadvantage of these mixtures, which contain low molecular weight amines, is that they have a lower storage stability, since the amines, particularly from thin layers, can easily exude.

JP-A 50/129214, filed on April 2, 1974 under the number 49/36614, describes a photopolymerizable mixture which, as the polymerizable compound, comprises a tetra (meth) acrylic acid ester of an N, N, N ', N'-tetrahydroxyalkyl- contains alkylenediamines. The tetrafunctional compound serves as a cross-linking agent.

It is also known that the radical polymerization of ethylenically unsaturated compounds can be initiated by irradiation with visible light in the presence of photoreducible dyes and reducing agents, for example amines (US Pat. No. 3,097,096). However, these initiator combinations are used essentially only in aqueous solution or in combination with water-soluble binders. Initiator combinations of photoreducible dyes and other reducing agents are described in US Pat. Nos. 3,597,343 and 3,488,269.

Photopolymerizable mixtures which only contain photoreducible dyes as initiators have hitherto been practically not used because of their low sensitivity to light.

JP-A 54/151024 describes a photopolymerizable mixture which contains an initiator combination of a merocyanine dye and a trihalomethyl-substituted s-triazine and is sensitive to visible light, for example an argon laser. However, the sensitivity of these mixtures to visible laser light is not sufficient for economical use.

EP-A 287 817 describes photopolymerizable mixtures which contain (meth) acrylic acid esters with urethane groups, tertiary amino groups and possibly urea groups in the molecule, polymeric binders and, as photoinitiators, a combination of a photoreducible dye, a radiation-sensitive trihalomethyl compound and an acridine , Phenazine or quinoxaline compound.

EP-A 321 826 describes similar mixtures with (meth) acrylic acid esters which contain no urethane groups.

US Pat. No. 3,717,558 describes metallocenes of elements from subgroups IIa to VIIIa in combination with a further photoinitiator with a carboxylic acid chloride group for use in photopolymerizable recording materials. These initiator combinations are very sensitive to oxygen and hydrolysis and therefore less suitable for the production of printing plates and resist materials. Further metallocenes and their use as photoinitiators in photopolymerizable mixtures are described in EP-A 119 162 and 122 223. These are titanocenes with good stability against air, which have a spectral sensitivity in the range from UV light to visible light. They contain, among other things, cyclopentadienyl residues and fluorinated phenyl residues as ligands. Furthermore, EP-A 242 330 and 269 573 describe photopolymerizable mixtures which contain a photoinitiator mixture consisting of a titanocene and a liquid photoinitiator of the hydroxy or aminoacetophenone type. With these materials, the light sensitivity that can be achieved is not sufficient for rapid imaging with a low-energy and at the same time inexpensive argon ion laser.

In the unpublished older European patent application 89117004.5, photopolymerizable mixtures are described which<ul id="ul0001" list-style="dash"><li>a polymeric binder,</li><li>a free-radically polymerizable compound with at least one polymerizable group,</li><li>a photo-reducible dye,</li><li>a radiation-cleavable trihalomethyl compound and</li><li>a metallocene compound, in particular a titanocene or zirconocene,</li></ul> contain. The metallocenes used are those which carry two optionally substituted cyclopentadienyl radicals and two substituted phenyl radicals as ligands. The phenyl radicals have at least one fluorine atom in the o-position to the bond and optionally contain further substituents, such as Cl, Br, alkyl or alkoxy groups; preferred and described in the examples are compounds with pentafluorophenyl radicals. These mixtures are extremely sensitive to light. Their shelf life, especially at elevated temperatures, is limited.

The object of the invention was to propose photopolymerizable mixtures which are suitable for the production of printing plates with a high circulation and photoresists with high resistance to processing solutions in the hardened state, which are sensitive to light in the near ultraviolet and in the visible spectral range, and by good thermal Characterize storage stability and are particularly suitable for laser beam recording in the visible range.

According to the invention, a photopolymerizable mixture is proposed which is an essential component<ul id="ul0002" list-style="none"><li>a) a polymeric binder,</li><li>b) a free-radically polymerizable compound having at least one polymerizable group,</li><li>c) a photoreducible dye</li></ul> contains.

The mixture according to the invention is characterized in that it is also<ul id="ul0003" list-style="none"><li>d) a dicyclopentadienyl bis-2,4,6-trifluorophenyl titanium or zircon</li></ul> contains.

The metallocenes used as an initiator component are known as such and also as photoinitiators, for example from US Pat. No. 4,590,287. The compounds of titanium are preferred. Such connections are e.g. B. described in EP-A 119 162 and 122 223.

The cyclopentadienyl groups can in particular be substituted by alkyl radicals having 1 to 4 carbon atoms, chlorine atoms, phenyl or cyclohexyl radicals or linked to one another by alkylene groups. The cyclopentadienyl groups are preferably either unsubstituted or substituted by alkyl radicals or chlorine atoms. The amount of metallocene compound is generally between 0.01 and 10, preferably 0.05 to 6 wt .-%, based on the non-volatile components of the mixture.

The mixture according to the invention contains a photoreducible dye as a further photoinitiator component. Suitable dyes are, in particular, xanthene, benzoxanthene, benzothioxanthene, thiazine, pyronine, porphyrin or acridine dyes.

Suitable xanthene and thiazine dyes are described, for example, in EP-A 287 817. Suitable benzoxanthene and benzothioxanthene dyes are described in DE-A 20 25 291 and EP-A 321 828.

For example, hematoporphyrin is suitable as the porphyrin dye and, for example, acriflavinium chloride hydrochloride is suitable as the acridine dye.

Examples of xanthene dyes are Eosin B (CI No. 45400), Eosin J (CI No. 45380), Eosin alcohol-soluble (CI 45386), Cyanosin (CI No. 45410), Rose Bengal, Erythrosin (CI No. 45430), 2.3 , 7-trihydroxy-9-phenyl-xanthene-6-one and rhodamine 6 G (CI No. 45160).

Examples of thiazine dyes are thionine (CI No. 52000), Azure A (CI No. 52005) and Azure C (CI No. 52002).

Examples of pyronine dyes are pyronine B (CI No. 45010) and pyronine GY (CI No. 45005). The amount of the photoreducible dye is generally between 0.01 and 10, preferably between 0.05 and 4% by weight, based on the non-volatile components of the mixture.

To increase the sensitivity to light, the mixtures according to the invention preferably also contain compounds with photolytically cleavable trihalomethyl groups, which are known per se as radical-forming photoinitiators for photopolymerizable mixtures. As such coinitiators, compounds with chlorine and bromine, in particular chlorine, have proven particularly useful as halogens. The trihalomethyl groups can be bonded directly or via a conjugated chain to an aromatic carbocyclic or heterocyclic ring. Preference is given to compounds having a triazine ring in the base which preferably carries 2 trihalomethyl groups, in particular those as described in EP-A 137452, DE-A 2718259 and DE-A 2243621. These compounds have strong light absorption in the near UV range, around 350-400 nm. Also suitable are coinitiators which absorb little or no absorption even in the spectral range of the copying light, such as trihalomethyltriazines which contain substituents with shorter mesomerizable electron systems or aliphatic substituents. Compounds with a different backbone which absorb in the shorter-wave UV range, for example phenyltrihalomethylsulfones or phenyltrihalomethylketones, for example phenyltribromomethylsulfone, are also suitable.

These halogen compounds are generally used in an amount of from 0.01 to 10, preferably from 0.05 to 4,% by weight, based on the nonvolatile constituents of the mixture.

The mixtures according to the invention optionally contain an acridine, phenazine or quinoxaline compound as a further initiator component. These compounds are known as photoinitiators and are described in DE-C 2027467 and 2039861. These compounds increase the sensitivity of the mixture, especially in the near ultraviolet range. Suitable representatives of this class of compounds are described in the DE-C mentioned. Examples are acridines substituted in the 9-position, such as 9-phenyl-, 9-p-methoxyphenyl- or 9-acetylamino-acridine, or acridine derivatives with fused-on aromatic nuclei, e.g. B. Benz (a) acridine. As a phenazine derivative, e.g. B. the 9,10-dimethyl-benz (a) phenazine suitable. Suitable quinoxaline derivatives are in particular the 2,3-diphenyl derivatives, which are preferably further substituted by methoxy groups in the two phenyl radicals. In general, the acridine derivatives are preferred. The amount of this component in the mixture is in the range from 0 to 10% by weight, preferably between 0.05 and 5% by weight. If a further increase in sensitivity of the mixture in the visible spectral range is desired, this can be achieved by adding a compound of the dibenzalacetone or coumarin type. This addition results in a higher resolution of the copy and a continuous sensitization of the mixture for the visible spectral range up to wavelengths of approximately 600 nm. Suitable representatives of these compounds are 4,4'-disubstituted dibenzalacetones, e.g. diethylamino-4'-methoxy-dibenzalacetone, or coumarin derivatives such as 3-acetyl-7-diethylamino-, 3-benzimidazolyl-7-diethylamino- or carbonyl-bis- (7 -diethylaminocoumarin). The amount of this compound is in the range from 0 to 10, preferably from 0.05 to 4,% by weight, based on the nonvolatile constituents of the mixture. The total amount of polymerization initiators is generally 0.05 to 20, preferably 0.1 to 10 wt .-%.

Polymerizable compounds suitable for the purposes of the invention are known and are described, for example, in US Pat. Nos. 2,760,863 and 30,60023.

Preferred examples are acrylic and methacrylic acid esters of di- or polyhydric alcohols, such as ethylene glycol diacrylate, polyethylene glycol dimethacrylate, acrylates and methacrylates of trimethylolethane, trimethylolpropane, pentaerythritol and dipentaerythritol and of polyvalent alicyclic alcohols or N-substituted acrylic and methacrylic acid amides. Reaction products of mono- or diisocyanates with partial esters of polyhydric alcohols are also advantageously used. Such monomers are described in DE-A 20 64 079, 23 61 041 and 28 22 190.

Polymerizable compounds which contain at least one photooxidizable and optionally at least one urethane group in the molecule are particularly preferred. Amino groups, urea groups, thio groups, which can also be constituents of heterocyclic rings, enol groups and carboxyl groups in combination with olefinic double bonds are particularly suitable as photooxidizable groups. Examples of such groups are triethanolamino, triphenylamino, thiourea, imidazole, oxazole, thiazole, acetylacetonyl, N-phenylglycine and ascorbic acid groups. Polymerizable compounds with primary, secondary and especially tertiary amino groups are preferred.

Examples of compounds with photooxidizable groups are acrylic and alkacrylic acid esters of the formula I.<chemistry id="chem0001" num="0001"><img file="EP0445624A2_D0001.tif" /></chemistry> wherein<dl id="dl0001"><dt>Q</dt><dd><chemistry id="chem0002" num="0002"><img file="EP0445624A2_D0002.tif" /></chemistry></dd><dt>R</dt><dd>an alkyl, hydroxyalkyl or aryl group,</dd><dt>R⁵ and R⁶</dt><dd>each represents a hydrogen atom, an alkyl group or alkoxyalkyl group,</dd><dt>R⁷</dt><dd>a hydrogen atom, a methyl or ethyl group,</dd><dt>x¹</dt><dd>a saturated hydrocarbon group with 2 to 12 carbon atoms,</dd><dt>x²</dt><dd>a (c + 1) -valent saturated hydrocarbon group in which up to 5 methylene groups can be replaced by oxygen atoms,</dd><dt>D¹ and D²</dt><dd>each a saturated hydrocarbon group with 1 to 5 carbon atoms,</dd><dt>E</dt><dd>a saturated hydrocarbon group with 2 to 12 carbon atoms, a cycloaliphatic group with 5 to 7 ring members, which may contain up to two N, O or S atoms as ring members, an arylene group with 6 to 12 carbon atoms or a heterocyclic aromatic group with 5 or 6 ring links,</dd><dt>a</dt><dd>0 or a number from 1 to 4,</dd><dt>b</dt><dd>0 or 1,</dd><dt>c</dt><dd>an integer from 1 to 3,</dd><dt>m</dt><dd>depending on the value of Q 2, 3 or 4 and</dd><dt>n</dt><dd>an integer from 1 to m</dd></dl> means, where all symbols of the same definition can be the same or different from each other. The compounds of this formula, their preparation and use are described in detail in EP-A 287 818. If more than one radical R or more than one radical of the type indicated in square brackets is bonded to the central group Q in the compound of the general formula I, these radicals can be different from one another.

Compounds in which all of the substituents of Q are polymerizable radicals, ie in which m = n, are generally preferred. In general, a = 0 in no more than one, preferably no radical, preferably a = 1.

When R is an alkyl or hydroxyalkyl group, it generally has 2 to 8, preferably 2 to 4, carbon atoms. The aryl radical R can in general be mononuclear or dinuclear, preferably mononuclear and optionally substituted by alkyl or alkoxy groups having up to 5 carbon atoms or halogen atoms.

If R⁵ and R⁶ are alkyl or alkoxyalkyl groups, these can contain 1 to 5 carbon atoms. R⁷ is preferably a hydrogen atom or a methyl group, especially a methyl group.

X¹ is preferably a straight-chain or branched aliphatic or cycloaliphatic radical preferably having 4 to 10 carbon atoms. X² preferably has 2 to 15 carbon atoms, of which up to 5 can be replaced by oxygen atoms. If it is pure carbon chains, generally those having 2 to 12, preferably 2 to 6, carbon atoms are used. X² can also be a cycloaliphatic group with 5 to 10 carbon atoms, in particular a cyclohexylene group. D¹ and D² may be the same or different and together with the two nitrogen atoms form a saturated heterocyclic ring with 5 to 10, preferably 6, ring members.

When E is an alkylene group, it preferably has 2 to 6 carbon atoms, and as an arylene group it is preferably a phenylene group. Cyclohexylene groups are preferred as cycloaliphatic groups, those with aromatic N or S as heteroatoms and with 5 or 6 ring members are preferred as aromatic heterocycles. The value of c is preferably 1.

Other suitable compounds with photooxidizable groups are compounds of the formula II<chemistry id="chem0003" num="0003"><img file="EP0445624A2_D0003.tif" /></chemistry> wherein Q, R, R⁵, R⁶, R⁷, m and n have the meaning given above and Q additionally represents a group<chemistry id="chem0004" num="0004"><img file="EP0445624A2_D0004.tif" /></chemistry> where E 'is a group of formula III<chemistry id="chem0005" num="0005"><img file="EP0445624A2_D0005.tif" /></chemistry> is in which c has the meaning as in formula I; a 'and b' are integers from 1 to 4.

The compounds of this formula, their preparation and use are described in detail in EP-A 316 706.

Other suitable compounds with photooxidizable groups are acrylic and alkacrylic acid esters of the formula IV<chemistry id="chem0006" num="0006"><img file="EP0445624A2_D0006.tif" /></chemistry> wherein<chemistry id="chem0007" num="0007"><img file="EP0445624A2_D0007.tif" /></chemistry><dl id="dl0002"><dt>X¹ '</dt><dd>C._iH_2i or<chemistry id="chem0008" num="0008"><img file="EP0445624A2_D0008.tif" /></chemistry></dd><dt>D³</dt><dd>a saturated hydrocarbon group with 4 to 8 carbon atoms, which forms a 5- or 6-membered ring with the nitrogen atom,</dd><dt>Z.</dt><dd>a hydrogen atom or a radical of the formula<chemistry id="chem0009" num="0009"><img file="EP0445624A2_D0009.tif" /></chemistry></dd><dt>i and k</dt><dd>integers from 1 to 12,</dd><dt>n '</dt><dd>depending on the value of Q '1, 2 or 3</dd></dl> means, and R⁷, X¹, X², D¹, D², a and b have the meaning given for formula I, where all symbols of the same definition may be the same or different and with each other in at least one substituent on the group Q a = o.

Of the compounds of the formula IV, preference is given to those which, in addition to a urea group, contain at least one urethane group. Groups of the formula are intended as urea groups<chemistry id="chem0010" num="0010"><img file="EP0445624A2_D0010.tif" /></chemistry> are considered in which the valences on nitrogen are saturated with optionally substituted hydrocarbon radicals. However, a valence on a nitrogen atom can also be bound to a further carbonylamide group (CONH), so that a biuret structure is formed.

The symbol a in formula IV is preferably 0 or 1; i is preferably a number from 2 to 10.

The polymerizable compounds of the formula IV are prepared analogously to the compounds of the formula I. The compounds of formula IV and their preparation are described in detail in EP-A 355 387.

The amount of polymerizable compounds in the photopolymerizable layer is generally about 10 to 80, preferably 20 to 60,% by weight, based on the non-volatile constituents.

Examples of binders that can be used are chlorinated polyethylene, chlorinated polypropylene, poly (meth) acrylic acid alkyl esters in which the alkyl group is, for example Is methyl, ethyl, n-butyl, i-butyl, n-hexyl or 2-ethylhexyl, copolymers of said (meth) acrylic acid alkyl esters with at least one monomer such as acrylonitrile, vinyl chloride, vinylidene chloride, styrene or butadiene; Polyvinyl chloride, vinyl chloride / acrylonitrile copolymers, polyvinylidene chloride, vinylidene chloride / acrylonitrile copolymers, polyvinyl acetate, polyvinyl alcohol, polyacrylonitrile, acrylonitrile / styrene copolymers, acrylonitrile / butadiene / styrene copolymers, polystyrene, polymethylstyrene, polyamides (e.g. nylon-6), polyamides (e.g. nylon-6) Methyl cellulose, ethyl cellulose, acetyl cellulose, polyvinyl formal and polyvinyl butyral.

Particularly suitable are binders which are insoluble in water, soluble in organic solvents and soluble or at least swellable in aqueous alkaline solutions.

Particular mention should be made of binders containing carboxyl groups, for example copolymers of (meth) acrylic acid and / or their unsaturated homologs, such as crotonic acid, copolymers of maleic anhydride or its half esters, reaction products of hydroxyl-containing polymers with dicarboxylic anhydrides and mixtures thereof.

Also suitable are reaction products from polymers which carry H-acidic groups which have been reacted in whole or in part with activated isocyanates, such as, for example, reaction products from hydroxyl-containing polymers with aliphatic or aromatic sulfonyl isocyanates or phosphinic acid isocyanates.

The following are also suitable: Polymers containing hydroxyl groups, such as, for example, copolymers of hydroxyalkyl (meth) acrylates, copolymers of allyl alcohol, copolymers of vinyl alcohol, polyurethanes or polyesters, and epoxy resins, provided that they carry a sufficient number of free OH groups, or are modified such that they are aqueous alkaline solutions are soluble, or those polymers which carry aromatically bound hydroxyl groups, such as condensation products of condensable carbonyl compounds, in particular formaldehyde, acetaldehyde or acetone, with phenols or copolymers of hydroxystyrenes. Finally, copolymers of (meth) acrylic acid amide with alkyl (meth) acrylates can also be used.

The polymers described above are particularly suitable if they have a molecular weight between 500 and 200,000 or more, preferably 1000 to 100,000 and either acid numbers between 10 and 250, preferably from 20 to 200, or hydroxyl numbers between 50 and 750, preferably from 100 to 500.

The following are mentioned as preferred alkali-soluble binders: Copolymers of (meth) acrylic acid with alkyl (meth) acrylates, (meth) acrylonitrile or the like, copolymers of crotonic acid with alkyl (meth) acrylates, (meth) acrylonitrile or the like, copolymers of vinyl acetic acid with alkyl (meth) acrylates, copolymers of maleic anhydride with if necessary Substituted styrenes, unsaturated hydrocarbons, unsaturated ethers or esters, esterification products of the copolymers of maleic anhydride, esterification products of hydroxyl-containing polymers with anhydrides of di- or polycarboxylic acids, copolymers of hydroxyalkyl (meth) acrylates with alkyl (meth) acrylates, (meth) acrylonitrile or the like , Copolymers of allyl alcohol with Substituted styrenes, copolymers of vinyl alcohol with alkyl (meth) acrylates or other polymerizable unsaturated compounds, polyurethanes, provided they have a sufficient number of free OH groups, epoxy resins, polyesters, partially saponified vinyl acetate copolymers, polyvinyl acetals with free OH groups, copolymers of hydroxystyrenes with alkyl (meth) acrylates or the like, phenol-formaldehyde resins, for example novolaks. The amount of the binder in the photosensitive layer is generally 20 to 90, preferably 40 to 80% by weight.

Depending on the planned application and the desired properties, the photopolymerizable layers can contain various substances as additives. Examples are: inhibitors to prevent thermal polymerization of the monomers, hydrogen donors, dyes, colored and uncolored pigments, color formers, indicators, plasticizers and chain transfer agents. These constituents are expediently to be selected so that they absorb as little as possible in the actinic radiation range which is important for the initiation process.

In the context of this description, actinic radiation should be understood to mean any radiation whose energy corresponds at least to that of visible light. Visible light and long-wave UV radiation are particularly suitable, but also short-wave UV radiation, laser radiation, electron and X-rays. The light sensitivity ranges from about 300 nm to 700 nm and thus spans a very wide range. By combining photoreducible dyes with photolytically cleavable halogen compounds and metallocenes, a synergistic initiator system is obtained, the activity of which, especially in the long-wave spectral range at or above 455 nm, is superior to the known photoinitiator combinations in photopolymerizable mixtures. The special metallocenes used according to the invention, in particular of dicyclopentadienyl-bis-2,4,6-trifluorophenyl titanium, surprisingly result in very good thermal stability of the layers in addition to very high photosensitivity.

Particularly high photosensitivities are obtained in combination with polymerizable compounds which contain photo-oxidizable groups. By replacing acridine, phenazine or quinoxaline compounds, which are used as coinitiators in otherwise the same photopolymerizable mixtures as z. B. are described in EP-A 287 817, by the above-described metallocene compounds or by additional use of the metallocenes in addition to the multinuclear heterocycles mentioned, mixtures having a substantially higher photosensitivity are obtained. The mixtures according to the invention are also considerably more sensitive to light than mixtures with known initiator combinations containing metallocenes.

The following may be mentioned as possible uses for the material according to the invention: recording layers for the photomechanical production of printing forms for letterpress printing, planographic printing, gravure printing, screen printing, relief printing, for example producing text in Braille, single copies, tanning pictures, pigment pictures etc. Mixtures for the photomechanical production of etching reserves, e.g. B. applicable for the production of name badges, copied circuits and for molded part etching.

The mixtures according to the invention are particularly important as recording layers for the production of planographic printing plates and for photoresist technology. As a layer support for the recording material according to the invention z. As aluminum, steel, zinc, copper and plastic films, for. B. from polyethylene terephthalate or cellulose acetate, and screen printing media such as Perlongaze, suitable. In many cases it is advantageous to subject the support surface to a pretreatment (chemical or mechanical), the aim of which is to correctly adjust the adhesion of the layer, to improve the lithographic properties of the support surface or to reduce the reflectivity of the support in the actinic region of the copy layer ( Antihalation).

The photosensitive materials are produced in a known manner. So you can take up the layer components in a solvent and apply the solution or dispersion by pouring, spraying, dipping, application with rollers, etc. on the intended support and then drying. Due to the broad spectral sensitivity of the recording material according to the invention, all light sources familiar to the person skilled in the art can be used, for example Tubular lamps, xenon pulse lamps, metal halide-doped high-pressure mercury lamps and carbon arc lamps. In addition, with the light-sensitive mixtures according to the invention, exposure in conventional projection and enlarging devices under the light of the metal filament lamp and contact exposure with conventional light bulbs is possible. The exposure can also be done with coherent light from a laser. Suitable for the purposes of the present invention are high-performance lasers, for example argon-ion, krypton-ion, dye, helium-cadmium and helium-neon lasers, which emit in particular between 250 and 650 nm. The laser beam can be controlled by means of a predetermined programmed line and / or raster movement.

It is generally favorable to largely remove the mixtures from the influence of atmospheric oxygen during the light polymerization. If the mixture is used in the form of thin copying layers, it is advisable to apply a suitable cover film which is not very permeable to oxygen. This can be self-supporting and can be removed before the copy layer is developed. Polyester films, for example, are suitable for this purpose. The cover film can also consist of a material that dissolves in the developer liquid or at least can be removed at the non-hardened points during development.

Suitable materials are e.g. As polyvinyl alcohol, polyphosphates, sugar, etc. Such cover layers generally have a thickness of 0.1 to 10, preferably 1 to 5 microns. The further processing of the materials is carried out in a known manner. For better crosslinking of the layer, reheating can be carried out after exposure. For development they are with a suitable developer solution, e.g. B. treated with organic solvents, but preferably with a weakly alkaline aqueous solution, the unexposed portions of the layer being removed and the exposed areas of the copying layer remaining on the support. The developer solutions can contain a small proportion, preferably less than 5% by weight, of water-miscible organic solvents. They can also contain wetting agents, dyes, salts and other additives.

During development, the entire top layer is removed together with the unexposed areas of the photopolymerizable layer.

Exemplary embodiments of the invention are given below. Parts by weight (Gt) and parts by volume (Vt) are in a ratio of g to ccm. Unless otherwise stated, percentage and quantity ratios are to be understood in weight units.

Examples 1-6 (Comparative Examples)

Electrochemically roughened and anodized aluminum with an oxide layer of 3 g / m 2, which had been pretreated with an aqueous solution of polyvinylphosphonic acid, was used as the substrate for printing plates. The support was coated with a solution of the following composition. All operations were carried out under red light:<dl id="dl0003"><dt>2.84 Gt</dt><dd>a 22.3% solution of a terpolymer of styrene, n-hexyl methacrylate and methacrylic acid (10:60:30) with the acid number 190 in methyl ethyl ketone,</dd><dt>1.49 pbw</dt><dd>Monomer according to Table 1,</dd><dt>0.04 pbw</dt><dd>Eosin alcohol-soluble (CI 45386),</dd><dt>0.03 pbw</dt><dd>2,4-bis-trichloromethyl-6- (4-styrylphenyl) -s-triazine and</dd><dt>0.01 pbw</dt><dd>Dicyclopentadienyl-bis-pentafluorophenyl titanium in</dd><dt>22 Gt</dt><dd>Propylene glycol monomethyl ether.</dd></dl>

The application was carried out by spin coating in such a way that a dry weight of 2.4 to 2.8 g / m 2 was obtained. The plate was then at 100 for two minutes^OC dried in a convection oven. The plate was then coated with a 15% aqueous solution of polyvinyl alcohol (12% residual acetyl groups, K value 4). After drying, a cover layer with a weight of 2.5 to 4 g / m² was obtained. The printing plate obtained was exposed using a 2 kW metal halide lamp at a distance of 110 cm under a 13-stage exposure wedge with density increments of 0.15. In order to test the sensitivity of the printing plates in visible light, a 3 mm thick edge filter from Schott with an edge transmittance of 455 nm and a silver film with uniform blackening (density 1.4) and uniform absorption over the effective spectral range were used as a gray filter on the exposure wedge assembled. The plates were exposed for 20 seconds and then for one minute to 100^OC warmed. They were then developed with a developer of the following composition:<dl id="dl0004"><dt>120 Gt</dt><dd>Sodium metasilicate x 9 H₂O,</dd><dt>2.13 pbw</dt><dd>Strontium chloride,</dd><dt>1.2 pbw</dt><dd>non-ionic wetting agent (coconut fatty alcohol polyoxyethylene ether with approx. 8 oxyethylene units) and</dd><dt>0.12 Gt</dt><dd>Antifoam in</dd><dt>4000 Gt</dt><dd>demineralized water.</dd></dl>

The plates were colored with bold printing ink. The fully cross-linked wedge stages shown in Table 2 were obtained.<tables id="tabl0001" num="0001"><img file="EP0445624A2_D0011.tif" /></tables>

Examples 7-12

Solutions of the following composition were spun onto the layer support given in Example 1 under the same conditions as there, so that a layer weight of 2.5 g / m 2 was obtained in each case:<dl id="dl0005"><dt>2.84 Gt</dt><dd>the terpolymer solution given in Example 1,</dd><dt>1.49 pbw</dt><dd>Monomer according to Table 1,</dd><dt>0.04 pbw</dt><dd>Eosin alcohol-soluble (CI 45386),</dd><dt>0.03 pbw</dt><dd>2,4-bis-trichloromethyl-6- (4-styrylphenyl) -s-triazine and</dd><dt>0.01 pbw</dt><dd>Dicyclopentadienyl-bis-2,4,6-trifluorophenyl titanium</dd><dt>22 Gt</dt><dd>Propylene glycol monomethyl ether.</dd></dl>

After applying a top layer of polyvinyl alcohol, the plates were exposed in the same manner as in Example 1 for 20 seconds and then developed. In order to test the sensitivity of the printing plates in visible light, a 3 mm thick edge filter from Schott with an edge transmittance of 455 nm and - if specified - a silver film with uniform blackening (density 1.1) as a gray filter were mounted on the exposure wedge. The fully cross-linked wedge stages listed in Table 3 were obtained:<tables id="tabl0002" num="0002"><img file="EP0445624A2_D0012.tif" /></tables>

A storage test at 80 was carried out with the printing plates from Examples 1-12 ^OC over a period of 4 hours in a convection oven. The exposure and development were carried out after 4 hours as indicated above.

The following result was found: Examples 1-6 gave no image on the aluminum support. The fully cross-linked wedge stages listed in Table 4 were found for Examples 7-12.<tables id="tabl0003" num="0003"><img file="EP0445624A2_D0013.tif" /></tables>

The one at 80 ^OC plates stored in C gave over 100,000 flawless prints even after 4 hours of storage.

Example 13

The coating solution from Example 7 was spun onto a 35 μm thick biaxially stretched polyethylene terephthalate film in such a way that a layer weight of 15 g / m 2 was obtained after drying. The layer was at 100 for three minutes^OC dried in a convection oven. Then the layer at 115^OC laminated at 1.5 m / min on a cleaned carrier, which consisted of an insulating plate with a 35 µm copper layer.

The layer was exposed by means of a 2 kW metal halide lamp (140 cm distance) under an edge filter 455 nm, as described in Example 1, with a step wedge as a template for 30 seconds and after removing the film with 0.8% sodium carbonate solution in a spray processor Developed 20 seconds. 6 fully cross-linked wedge steps were obtained. The cross-linked layer was resistant to the iron (III) chloride solution common in printed circuit board technology. The etch resistance was good.