IE911389A1

IE911389A1 - Process for the production of printing formes or¹photoresists by imagewise irradiation of a¹photopolymerizable recording material

Info

Publication number: IE911389A1
Application number: IE138991A
Authority: IE
Original assignee: Hoechst Ag
Priority date: 1990-04-26
Filing date: 1991-04-25
Publication date: 1991-11-06
Also published as: DE59108857D1; EP0453953B1; KR910018851A; ES2106039T3; BR9101676A; EP0453953A3; FI911979A0; DE4013358A1; KR0180737B1; CA2041191A1; FI103696B; JP3118520B2; EP0453953A2; FI911979A; FI103696B1; JPH04261544A

Abstract

A description is given of a process for the production of printing plates or photoresists by imagewise exposure of a photopolymerisable registration material whose photopolymerisable layer contains a polymeric binder, a free-radical-polymerisable ethylenically unsaturated compound containing at least one terminal ethylenical double bond, and a metallocene compound as photoinitiator. In the process, the material is heated for a short time after the imagewise exposure, exposed for a short time to visible light having a wavelength of at least 400 nm without artwork before, at the same time as or after the imagewise exposure, and then developed. The process makes it possible to shorten the image exposure or irradiation substantially and is suitable, in particular, for the projection exposure or laser exposure of printing plates.

Description

Process for the production of printing formes or photoresists by imagewise irradiation of a photopolymerizable recording material The invention relates to a process for the production of printing forms or photoresists by imagewise irradiation of a photopolymerizable recording material containing a polymer binder, a compound polymerizable by free radicals, in particular an acrylic or alkacrylic ester, and a photoinitiator or a photoinitiator combination.

From DE-B 1,214,085 (US-A 3,144,331) it is known to expose, in order to restore the sensitivity of photopolymerizable recording materials comprising a printing plate support and a photosensitive layer and whose sensitivity has decreased due to absorption of molecular oxygen, the photosensitive layer to 70 to 98% of the amount of radiation of actinic radiation necessary for initiating photopolymerization. For example, exposure takes place through the transparent printing plate support, the wavelengths of the actinic radiation used being such that only 10 to 7 0% of the radiation is absorbed by the photopolymerizable layer. In this process, one diffuse and one imagewise exposure are in principle carried out. The diffuse or preexposure is then followed by imagewise exposure up to the full amount of radiation.

A process is disclosed in US-A 4,716,097 in which a photopolymerizable layer containing a dye is first exposed to light having a wavelength above 400 nm and an intensity of at least 1500 lumen/m2 for approximately 60 minutes diffuse and then imagewise.

DE-A 2,412,571 describes a process for the curing of a light-curable layer of a printing plate in which first ,£ 911389 HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 2 diffuse exposure is carried out for a short time and then imagewise exposure until the layer in the exposed regions has virtually completely been cured. The diffuse exposure lasts not more than 90% of the time necessary for curing the polymer layer at the same intensity of radiation not only for the preexposure but also for the imagewise exposure.

EP-A 53,708 describes a process for the production of relief copies in which the photopolymerizable layer of a recording material is subjected to imagewise exposure, is heated to elevated temperatures for a short time before or after exposure and is then developed.

EP-A 284,938 describes photopolymerizable mixtures containing (meth)acrylic esters with urethane groups, tertiary amino groups and possibly urea groups in the molecule, polymer binders and a photoreducible dye, if desired in combination with a radiation-sensitive trihalomethyl compound, as the photoinitiator. EP-A 321,827 describes similar mixtures containing (meth)acrylic esters but no urethane groups.

EP-A 364,735 describes photopolymerizable mixtures containing a polymer binder, a compound polymerizable by free radicals and containing at least one polymerizable group, a photoreducible dye, a trihalomethyl compound which can be cleaved by radiation and - a metallocene compound, in particular a titano30 cene or zirconocene.

The metallocenes used are those carrying two substituted or unsubstituted cyclopentadienyl radicals and two substituted phenyl radicals as ligands. The earlier German Patent Application P 4,007,428.5, which is not a HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 3 prior publication, describes further photopolymerizable mixtures of the above composition containing a dicyclopentadienylbis-2,4,6-trifluorophenyltitanium or -zirconium as metallocene. These mixtures have extremely high photosensitivity.

The earlier German Patent Application P 4,011,023.0, which is not a prior publication, describes an aftertreatment apparatus for imagewise exposed printing plates comprising an exposure station for full-area exposure of the printing plate and a heating station. The full-area exposure is carried out using light in the spectral range from 500 to 700 nm. No detailed information about the composition of the photopolymerizable printing plates which are processed is given.

The object of the invention was to propose a process for the production of printing formes, in particular planographic printing formes, or photoresists by imagewise exposure of a photopolymerizable recording material which already has very high photosensitivity and to propose suitable processing steps, by means of which the energy requirement during exposure of the image can be reduced substantially, thus achieving a correspondingly higher photosensitivity in practice.

According to the invention, a process for the production of printing formes or photoresists by imagewise irradiation of a photopolymerizable recording material is proposed, whose photopolymerizable layer contains a polymer binder, an ethylenically unsaturated compound polymerizable by free radicals and containing at least one terminal ethylenic double bond and a polymerization initiator or an initiator combination forming free radicals upon irradiation, in which the material is heated after the imagewise irradiation for a short time and then developed.

HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 4 The process according to the invention comprises using a metallocene compound as the polymerization initiator radical-forming and exposing the material before, simultaneously with or after the imagewise irradiation for a short time to visible light having a wavelength of at least 400 nm without an original.

The heating and the exposure without an original can advantageously be carried out in an apparatus such as described in the earlier Application P 4,011,023.0. The sequence of the exposure steps is as desired, preferably the material is first subjected to imagewise exposure or irradiation, then exposed without an original and finally heated.

The imagewise irradiation can preferably be carried out by projection using standard copying light or laser radiation. Examples of projection light sources which can be used are mercury vapor lamps, xenon lamps, metal halide lamps, flashlight lamps, carbon arc lamps and the like, it being possible for the intensity and/or duration of exposure to be kept low. Suitable laser light sources are in particular lasers emitting in the visible spectral range, for example at 488 and 514 nm. For this purpose, for example, argon ion lasers having a relatively low output, for example 10 to 25 mW, can advantageously be used. The dosage of imagewise irradiation is preferably in the range from 5 to 50% of the dosage necessary for complete curing of the layer without further treatment. The remainder of the amount of energy required is supplied according to the invention by the combination of diffuse exposure, i.e. without an original, followed by heating.

For exposure without an original, a light source of relatively low output, for example a fluorescent lamp, is used, which emits a very high proportion of light having a wavelength of more than 500 nm. The emission HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 5 range is in general between 400 and 700, preferably between 450 and 650, nm. The layer surface should in general be exposed to an intensity of about 10 to 80 lux. The doses have to be selected such that complete curing is effected thereby in combination with the image exposure and heat treatment on the image areas to be cured. It must be ensured that the non-image areas do not become cured by the diffuse exposure in combination with the heating to such an extent that they are no longer completely soluble in the developer. The desired image differentiation can be achieved with an image exposure or irradiation in the abovementioned range of 5 to 50% of the amount of radiation required.

Heating is carried out as the last treatment step before development in a manner known per se. To this end, the completely exposed material is heated to a temperature in the range from 60 to 140, preferably from 80 to 120°C, in particular from 90 to 110°C, for approximately 10 seconds to 2 minutes. In most cases, the treatment time required is in the range between 30 and 80 seconds. During this treatment, the temperature must be measured, when printing plates on metal supports, in particular aluminum, are heated, advantageously on the back of the plate, for example using commercially available temperature test strips. Heating can take place by air circulation, by contact heating or by infrared radiation.

Surprisingly, it has been found that the process according to the invention results in the desired increase in sensitivity only in very specific photopolymerizable materials. Thus, it has been shown that adequate reexposure and reheating achieves virtually no increase in sensitivity, if a known photopolymerizable material is used which contains 9-phenylacridine as the photoinitiator and trimethylolethane triacrylate as the monomer. If, however, a metallocene, in particular a titanocene or zirconocene, is used as the photoinitiator, HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 6 an increase in photosensitivity by several degrees is achieved by the same treatment.

The metallocenes used as initiators are known as such and also as photoinitiators, for example from US-A 3,717,558, 4,590,287 and 4,707,432. Preferably, metallocenes of elements from subgroup IV of the periodic table of the elements, in particular compounds of titanium and zirconium, are used. Compounds of this type are described in EP-A 364,735. Of the large number of known metallocenes, in particular titanocenes, compounds of the general formula are preferred. In this formula, Me is a tetravalent metal atom, in particular Ti or Zr, R1 and R2 are identical or different cyclopentadienyl radicals, which may be substituted, and R3 and R4 are identical or different phenyl radicals which may also be substituted.

The cyclopentadienyl groups can be substituted, in particular by alkyl radicals having 1 to 4 carbon atoms, chlorine atoms, phenyl or cyclohexyl radicals or linked to one another by alkylene groups. They are preferably unsubstituted or substituted by alkyl radicals or chlorine atoms.

R3 and R4 are preferably phenyl groups which contain at least one fluorine atom in the o position relative to the bond and for the rest can be substituted by halogen atoms, such as F, Cl or Br, alkyl or alkoxy groups having 1 to 4 carbon atoms, a polyoxyalkylene group which may be HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 7 etherified or esterified, or a heterocyclic group, for example a pyrrolyl radical. The polyoxyalkylene group in general has 1 to 6 oxyalkylene units and is preferably in the 4 position of the phenyl radical and can be etheri5 fied or esterified by an alkyl or acyl radical having 1 to 18 carbon atoms; it is in particular a polyoxyethylene group.

The relative amount of metallocene compound is in general between 0.01 and 10, preferably 0.05 to 8% by weight, relative to the photopolymerizable layer.

The photopolymerizable layer can contain a photoreducible dye as a further photoinitiator constituent. 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 2,025,291 and in EP-A 321,828.

An example of a suitable porphyrin dye is haematoporphyrin and an example of a suitable acridine dye is acriflavinium chloride hydrochloride.

Examples of xanthene dyes are Eosin B (C.I. No. 45400), Eosin J (C.I. No. 45380), Eosin alcohol-soluble (C.I. 45386), Cyanosine (C.I. No. 45410), Rose Bengal, Erythrosine (C.I. No. 45430), 2,3,7-trihydroxy9-phenylxanthen-6-one and Rhodamin 6 G (C.I. No. 45160).

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

Examples of pyronine dyes are Pyronin B (C.I. No. 45010) and Pyronin GY (C.I. No. 45005). The amount of HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 8 photo-reducible dye is in general between 0.01 and 10, preferably between 0.05 and 4, % by weight of the film.

To increase the photosensitivity, the photopolymerizable layers can additionally contain compounds having trihalo5 methyl groups which can be cleaved photolytically, these compounds being known per se as free-radical forming photoinitiators for photopolymerizable mixtures. In particular, compounds containing chlorine and bromine, in particular chlorine, as halogens have proved suitable as coinitiators of this type. The trihalomethyl groups can be bound to an aromatic carbo- or heterocyclic ring directly or via a through-conjugated chain. Preference is given to compounds having a triazine ring in the parent structure which in turn preferably carries 2 trihalo15 methyl groups, in particular to those described in EP-A 137,452, DE-A 2,718,259 and DE-A 2,243,621. Compounds with a different parent structure, which absorb in the shorter UV wavelength region, for example phenyl trihalomethyl sulfones or phenyl trihalomethyl ketones, for example phenyl tribromomethyl sulfone, are also suitable. The halogen compounds are in general used in an amount of 0.01 to 10, preferably 0.05 to 4, % by weight of the film.

The photopolymerizable layers can contain, if desired, acridine, phenazine or quinoxaline compounds as further initiator constituents. These compounds are known as photoinitiators and described in DE-C 2,027,467 and 2,039,861. The total amount of polymerization initiators is in general 0.05 to 20, preferably 0.1 to 10, % by weight.

Polymerizable compounds which are suitable for the purposes of the invention are known and described, for example, in US-A 2,760,863 and 3,060,023.

Preferred examples are acrylic and methacrylic esters of HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 9 di- or polyhydric alcohols, such as ethylene glycol diacrylate, polyethylene glycol dimethacrylate, acrylates and methacrylates of trimethylolethane, trimethylolpropane, pentaerythritol and dipentaerythritol and of polyhydric alicyclic alcohols or N-substituted acryl- and methacrylamides. Reaction products of mono- or diisocyanates with partial esters of polyhydric alcohols are also advantageously used. Monomers of this type are described in DE-A 2,064,079, 2,361,041 and 2,822,190.

Polymerizable compounds containing at least one photooxidizable and, if desired, at least one urethane group in the molecule are particularly preferred. Suitable photooxidizable groups are in particular 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. Examples of groups of this type are triethanolamino, triphenylamino, thiourea, imidazole, oxazole, thiazole, acetylacetonyl, N-phenylglycine and ascorbic acid groups. Polymerizable compounds having primary, secondary and in particular tertiary amino groups are preferred.

Examples of compounds containing photooxidizable groups are acrylic and alkacrylic esters of the formula I in which Q is -N-, -N-E-N-, -N Nor —S— R R5 and R6 is an alkyl, hydroxyalkyl or aryl group, are each a hydrogen atom, an alkyl group or alkoxyalkyl group, is a hydrogen atom, a methyl or ethyl group, HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 10 X1 is a saturated hydrocarbon group having 2 to 12 carbon atoms, X2 is a (c+1)-valent saturated hydrocarbon group in which up to 5 methylene groups can be replaced by oxygen atoms, D1 and D2 are each a saturated hydrocarbon group having to 5 carbon atoms, E is a saturated hydrocarbon group of 2 to 12 carbon atoms, a cycloaliphatic group of 5 to 7 ring members, which, if desired, can contain up to two N, 0 or S atoms as ring members, an arylene group of 6 to 12 carbon atoms or a heterocyclic aromatic group of 5 or 6 ring members, a is 0 or a number from 1 to 4, b is 0 or 1, c is an integer from 1 to 3, m is, depending on the valency of Q, 2, 3 or 4 and 20 n is an integer from 1 to m, it being possible for all symbols of the same definition to be identical to or different from one another. The compounds of this formula, their preparation and use are described in detail in EP-A 287,818. If in the compound of the general formula I more than one radical R or more than one radical of the type indicated in square brackets is bound to the central group Q, these radicals can be different from one another.

Compounds in which all substituents of Q are polymer30 izable radicals, i.e. in which m is n, are in general preferred. In general, a is 0 in not more than one radical, preferably in no radical? preferably a is 1.

If R is an alkyl or hydroxyalkyl group, this group has in general 2 to 8, preferably 2 to 4, carbon atoms. The aryl radical R can in general be substituted on one or two rings, preferably on one ring, and may be substituted by HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 11 alkyl or alkoxy groups of up to 5 carbon atoms or halogen atoms.

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

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

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

Further suitable compounds containing photooxidizable groups are compounds of the formula II R(m-n) QC (_ch2“?°) a · b ' -¾ I 6 'h2 (ID R7 I ooc-ch=ch2 in which Q, R, R5, R6, R7, m and n have the abovementioned meaning and Q can additionally be a group HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 12 I I -N-E'-Nin which E' is a group of the formula III CH- -CH2-CHOH-CH2-(0- -c- -O-CH2-CHOH-CH2-)c (III) CHin 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.

Further suitable compounds having photooxidizable groups are acrylic and alkacrylic esters of the formula IV Q‘[(-X1'CH2O)a-CONH(-X1-NHCOO)b-X2-OOC-C=CH2]n, (IV) in which Q' /°\ -N ND2 / is -N-, / \ or D3 N' is CiH2i or R7 CiH2i_iO-CONH ( -Xx-NHC00) b-X2-OOC-C=CH2, is a saturated hydrocarbon group having 4 to 8 carbon atoms which, together with the nitrogen atom, forms a 5- or 6-membered ring, is a hydrogen atom or a radical of the formula CkH^-O-CONH ( -X1-NHCO) b-X2-OOC=CH2 20 i and k are integers from 1 to 12, n' is, depending on the valency of Q', 1, 2 or 3, and R7, X1, X2, D1, D2, a and b have the meaning given under formula I, it being possible for all symbols of the same definition to be identical to or different from one HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 13 another and a in at least one substituent on the group Q being 0.

Of the compounds of the formula IV, those are preferred which contain at least one urethane group apart from a urea group.

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 the formula IV and their preparation are described in detail in EP-A 355,387.

The percentages of polymerizable compounds in the photopolymerizable film is in general about 10 to 80, preferably 20 to 60, % by weight, relative to the non-volatile components.

Examples of binders which can be used are chlorinated polyethylene, chlorinated polypropylene, polyalkyl (meth)acrylates, in which the alkyl group is, for example, methyl, ethyl, n-butyl, i-butyl, n-hexyl or 2-ethylhexyl, copolymers of the alkyl (meth)acrylates 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 (for example nylon-6), polyurethanes, methyl cellulose, ethyl cellulose, acetyl cellulose, polyvinyl formal and polyvinyl butyral.

Binders which are insoluble in water, soluble in organic HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 14 solvents and soluble or at least swellable in aqueous alkaline solutions are particularly suitable.

Carboxyl-containing binders, for example copolymers comprising (meth)acrylic acid and/or unsaturated homologues thereof, such as crotonic acid, copolymers of maleic anhydride or its monoesters, reaction products of hydroxyl-containing polymers with dicarboxylic anhydrides and mixtures thereof, should be mentioned in particular.

Reaction products of polymers carrying groups with acidic 10 hydrogen, which have been completely or partially reacted with activated isocyanates, such as, for example, reaction products of hydroxyl-containing polymers with aliphatic or aromatic sulfonyl isocyanates or phosphinyl isocyanates, are also suitable.

The following are also suitable: hydroxyl-containing polymers, such as, for example, hydroxyalkyl (meth)acrylate copolymers, allyl alcohol copolymers, vinyl alcohol copolymers, polyurethanes or polyesters, and epoxy resins, as long as they carry a sufficient number of free OH groups or are modified in such a manner that they are soluble in aqueous-alkaline solutions, or polymers of this kind carrying aromatically bound hydroxyl groups, such as, for example, condensation products of condensable carbonyl compounds, in particular formaldehyde, acetaldehyde or acetone, with phenols or hydroxystyrene copolymers. Finally, copolymers of (meth)acrylamide with alkyl (meth)acrylates can also be used.

The polymers described above are suitable in particular if they have a molecular weight between 500 and 200,000 or more, preferably 1,000 to 100,000, and either acid numbers between 10 and 250, preferably 20 to 200, or hydroxyl numbers between 50 and 750, preferably 100 to 500. The amount of binder in the photosensitive layer is in general 20 to 90, preferably 40 to 80, % by weight.

IE 911389 HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 15 Depending on the intended use and the desired properties, a wide range of substances can be present as additives in the photopolymerizable layers. Examples are: inhibitors for preventing thermal polymerization of the monomers, hydrogen donors, dyes, colored and uncolored pigments, color formers, indicators, plasticizers and chaintransfer agents. These components are advantageously selected in such a manner that they have the lowest possible absorption in the actinic radiation region important for the initiation process.

In the context of this description, actinic radiation is understood to mean any radiation whose energy corresponds at least to that of visible light. In particular visible light and long-wave UV radiation, but also short-wave UV radiation, laser radiation, electron and X-ray radiation are suitable. The photosensitivity ranges from about 300 nm to 700 nm.

Possible applications for the process according to the invention are: the photomechanical production of printing formes for relief printing, offset printing, intaglio printing, screen printing, of relief copies, for example production of texts in braille, of individual copies, dye images, pigment images, and the like. Furthermore, the process can be used for the photomechanical production of etch resists, for example for manufacturing name tags, copied circuits and for chemical milling. The preparation of planographic printing plates and the photoresist technique are of particular importance.

Examples of suitable supports are aluminum, steel, zinc, copper and plastic sheets, for example those made of polyethylene terephthalate or cellulose acetate, and screen printing supports, such as perlon gauze. In many cases, it is advantageous to subject the surface of the support to a pretreatment (chemically or mechanically), with the aim of properly adjusting the adhesion of the HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 16 layer, to improve the lithographic properties of the surface of the support or to reduce the reflectance of the support in the actinic region of the copying layer (antihalation).

It is in general advantageous to protect the photopolymerizable materials during the photopolymerization substantially against the effect of air oxygen. In the case where the mixture is applied in the form of thin copying layers, it is recommended to apply a suitable top film which has low permeability to oxygen. This film may be self-supporting and removed before developing the copying layer. For this purpose, for example, polyester films are suitable. The top film can also be made of a material which is soluble in the developer liquid or can at least be removed at the uncured areas during the development.

Examples of materials which are suitable for this are polyvinyl alcohol, polyphosphates, sugars, and the like. Top coats of this type in general have a thickness of 0.1 to 10, preferably 1 to 5, pm.

For development, the materials are treated with a suitable developer solution, for example, with organic solvents, but preferably with a weakly alkaline aqueous solution, in which the unexposed portions of the layer are removed and the exposed areas remain on the support.

The developer solutions can contain a small portion, preferably less than 5% by weight, of water-miscible organic solvents. They can further contain wetting agents, dyes, salts and other additives.

The development removes the entire top coat together with the unexposed areas of the photopolymerizable layer.

Working examples of the invention are given below. Therein, parts by weight (pbw) relate to parts by volume HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 17 (pbv) as the gram relates to cubic centimeters. Percentages and amounts are by weight, unless stated otherwise.

Examples 1-7 (comparative examples) Electrochemically roughened and anodized aluminum having 5 an oxide layer of 3 g/m2 and having been pretreated with an aqueous solution of polyvinylphosphonic acid was used as the support for printing plates. The support was coated with a solution of the following composition. All these operations were carried out under red light: 2.84 pbw of a 22.3% strength solution of a terpolymer comprising styrene, n-hexyl methacrylate and methacrylic acid (10:60:30) and having an acid number of 190 in methyl ethyl ketone, 1.49 pbw of the monomer according to Table 1, 0.04 pbw of Eosin alcohol-soluble (C.l. 45386), 0.03 pbw of 2,4-bis-trichloromethyl-6-(4-styrylphenyl)s-triazine and 0.01 pbw of dicyclopentadienylbis(pentafluorophenyl)titanium in 22 pbw of propylene glycol monomethyl ether.

The mixture was applied by spin-coating in such a manner that a dry weight of 2.4 to 2.8 g/m2 was obtained. The plate was then dried for two minutes at 100 °C in a through-circulation drying oven. The plate was then coated with a 15% strength aqueous solution of polyvinyl alcohol (12% of residual acetyl groups, K value 4). After drying, a top coat having a weight of 2.5 to 4 g/m2 was obtained. The printing plate obtained was exposed to a 2 kW metal halide lamp at a distance of 110 cm under a 1330 step exposure wedge at density increments of 0.15. To test the sensitivity of the printing plates in visible light, a 3 mm thick edge filter from Schott with a transmittance edge of 455 nm and a silver film having uniform darkening (density 1.4) and uniform absorption over the effective spectral range as a gray filter were HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 18 mounted on the exposure wedge. The plates were exposed for 10 seconds and then heated to 100°C for one minute. They were then developed using a developer of the following composition: 120 pbw 2.13 pbw 1.2 pbw 0.12 pbw 4000 pbw of sodium metasilicate x 9 H2O, of strontium chloride, of nonionic wetting agent (coconut alcohol/polyoxyethylene ether having 8 oxyethylene units) and of antifoam in of fully deionized water. fatty about The plates were coated with fatty printing ink. The fully crosslinked wedge steps given in Table 2 were obtained.

Table 1 Example No.

Monomer 4 Reaction product of 1 mol of triethanolamine with 3 mol of isocyanatoethyl methacrylate, Reaction product of 1 mol of N,N'-bis (β-hydroxyethyl) piperidine with 2 mol of isocyanatoethyl methacrylate, Reaction product of 1 mol of triethanolamine with 3 mol of glycidyl methacrylate, Reaction product of 1 mol of 2,2,4-trimethylhexamethylene diisocyanate with 2 mol of 2-hydroxyethyl methacrylate, Reaction product of 1 mol of hexamethylene diisocyanate with 1 mol of 2-hydroxyethyl methacrylate and 0.33 mol of triethanolamine, Trimethylolethane triacrylate, Reaction product of 1 mol of hexamethylene HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 19 diisocyanate with 0.5 mol of 2-hydroxyethyl methacrylate and 0.25 mol of 2-piperidinoethanol.

Examples 8-14 The printing plates described in Examples 1 to 7 were produced as described there and subjected to imagewise exposure. They were then reexposed over the entire area with diffuse light from a fluorescent lamp emitting light of about 400 to 700 nm, whose spectral portion below 500 nm was absorbed by a filter, at a light intensity of lux for 20 seconds, followed by heating as in Examples 1 to 7 and development. The number of the wedge steps obtained is shown in Table 2.

Table 2 Example No. Gray filter Wedge steps 1 yes 6 - 7 2 yes 7 3 yes 5 - 9 20 4 yes 4 - 5 5 yes 5 - 7 6 yes 6 no 1 - 2 25 7 yes 8 - 9 8 yes 9 - 11 9 yes 10 10 yes 8 - 12 30 11 yes 7 - 8 12 yes 8 - 10 13 yes 2 - 3 13 no 3 - 5 35 14 yes 11 - 12 no image Example 15 A solution of the following composition was spin-coated HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 20 onto the supports mentioned in Examples 1 to 7 under the same conditions as there, in such a manner that a coating weight of 2.5 g/m2 was obtained: 2.84 pbw 1.49 pbw 0.04 pbw 0.03 pbw 0.01 pbw pbw of the terpolymer solution mentioned in Example 1, of the monomer according to Example 7, of Eosin alcohol-soluble (C.I. 45386), of 2,4-bis(trichloromethyl)-6-(4-styrylphenyl)s-triazine and 0.01 pbw of dicyclopentadienyl bis(2,4,6-trifluorophenyl ) titanium in of propylene glycol monomethyl ether.

After applying a top coat comprising polyvinyl alcohol, the plate was exposed in the same manner as in Examples 15 1 to 7 for 5 seconds and then developed. To test the sensitivity of the printing plates in visible light, a 3 mm thick edge filter from Schott with a transmittance edge of 455 nm and a silver film having uniform darkening (density 1.1) as gray filter were mounted on the exposure 20 wedge. 8 to 9 fully crosslinked wedge steps were obtained. In a further experiment, the plate was exposed to diffuse reexposure as mentioned in Examples 8-14. 11 to 12 fully crosslinked wedge steps were obtained.

In both cases, the printing plates were developed 25 scum-free and gave more than 150,000 excellent prints .

Example 16 A photopolymerizable printing plate produced as in Example 7 was irradiated in a commercially available film exposure apparatus by means of an argon ion laser (λ = 488 nm) with 182 /ij/cm2 and processed without reexposure as in Example 7. More than 150,000 excellent prints were obtained.

HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 21 The same plate was reexposed after laser irradiation with 375 lux seconds as described in Example 14. It was found that under these conditions an irradiation energy of only 32 pJ/cm2 was required for completely curing the plate.

Again more than 150,000 prints were obtained.

In a further experiment, reexposure using 500 lux seconds was carried out, requiring only 18 ^J/cm2 for the laser imaging.

Example 17 The coating solution from Example 7 was spin-coated onto a biaxially oriented 35 μία thick polyethylene terephthalate film in such a manner that a coating weight of 15 g/m2 was obtained after drying. The film was then dried at 100 °C for three minutes in a through-circulation drying oven. The film was then laminated onto a cleaned support composed of an insulator plate coated with a 35 Mm copper layer at 115°C and 1.5 m/min.

The film was exposed for 30 seconds to a 2 kW metal halide lamp (distance 140 cm) under an edge filter 455 nm, as described in Example 1, using a step wedge as the original, and reexposed followed by heating as described in Examples 1 to 7 and, after removing the film, was developed for 20 seconds with 0.8% strength sodium carbonate solution in a spraying processor. 8 fully crosslinked wedge steps were obtained. The crosslinked film was resistant to iron(III) chloride solution which is common in printed circuit technology. The resistance to etching was good.

HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 22 Example 18 (Comparative Example) The following coating solution was applied to the support described in Examples 1 to 7 and dried: pbw of a methacrylic acid/methyl methacrylate mixed polymer having an acid number of 115, pbw of trimethylolethane triacrylate, pbw of dihydroxyethoxyhexane and pbw of 9-phenylacridine in pbw of 2-methoxyethanol The plate was exposed to a 5,000 W metal halide lamp under a step wedge for 35 seconds, followed by heating as in Example 1. 6 to 7 fully crosslinked wedge steps were obtained. In a further experiment, the same plate was only exposed for 15 seconds, subjected to diffuse re15 exposure after the image exposure with 300 lux seconds and then heated. No image was obtained. Diffuse reexposure with 300 lux seconds after an unchanged image exposure of 35 seconds likewise gave 6 to 7 fully crosslinked wedge steps.

Claims

1. Patent claims

1. A process for the production of printing formes or photoresists by imagewise irradiation of a photopolymerizable recording material whose photopolymerizable 5 layer contains a polymer binder, an ethylenically unsaturated compound polymerizable by free radicals and containing at least one terminal ethylenic double bond and a polymerization initiator or an initiator combination forming free radicals upon irradiation, in which the 10 material is heated after the imagewise irradiation for a short time and then developed, which comprises using a metallocene compound as the free radical-forming polymerization initiator and exposing the material before, simultaneously with or after the imagewise exposure to 15 visible light having a wavelength of at least 400 nm without an original for a short time.

2. The process as claimed in claim 1, wherein the material is subjected to imagewise exposure with an irradiation energy corresponding to 5 to 50% of the 20 energy necessary for complete curing of the layer without exposure in the absence of an original and without additional heating.

3. The process as claimed in claim 1, wherein the imagewise irradiation is carried out using laser light. 25 4. The process as claimed in claim 1, wherein the imagewise irradiation is carried out by projection exposure using actinic light. 5. The process as claimed in claim 1, wherein the imagewise exposed material is additionally heated to a 30 temperature in the range from 60 to 140°C. 6. The process as claimed in claim 1 or 5, wherein the material is additionally heated for 10 to 120 seconds . 7. The process as claimed in claim 1 or 2, wherein 35 the additional heating and reexposure are of such an HOECHST AKTIENGESELLSCHAFT - Werk KALLE-ALBERT - 24 intensity that the image areas are completely cured and the non-image areas remain completely soluble in the developer. 8. The process as claimed in claim 1, wherein the

4. 5 photopolymerizable recording material is first subjected to imagewise irradiation, then exposed without an original and then heated.

5. 9. The process as claimed in claim 1, wherein a photoreducible dye is added to the photopolymerizable

6. 10 layer as a coinitiator. 10. The process as claimed in claim 1 or 9, wherein the compound polymerizable by free radicals contains at least one photooxidizable group.

7. 11. The process as claimed in claim 9, wherein a trihalomethyl compound which can be cleaved by radiation is additionally incorporated in the photopolymerizable layer.

8. 12. The process as claimed in claim 1, wherein the metallocene is a titanocene or zirconocene.

9. 13. The process as claimed in claim 9, wherein the photoreducible dye is a xanthene, thiazine, pyronine, porphyrin or acridine dye.

10. 14. a process as claimed in claim 1, substantially as hereinbefore described and exemplified.

11. 15. Printing formes or photoresists whenever produced by a process claimed in a preceding claim.