EP1359008B1 - Radiation-sensitive mixture, recording material using this mixture, and method for preparing a printing plate - Google Patents

Description

The invention relates to a radiation-sensitive (photopolymerizable) mixture with a polymeric binder, a radically photopolymerizable component, a Infrared absorber and a triazine. It continues to apply Recording material with a support and a radiation-sensitive Layer.

A mixture of the type mentioned is already in EP-A 0 369 645. It comprises a free-radically polymerizable Monomer and a soluble therein photoinitiator system, the trihalomethyl-substituted 1,3,5-triazine, a sensitizer for the triazine and an electron-donor compound with a Oxidation potential of greater than zero and less than that of 1,4-dimethoxy-benzene contains. Sensitizers are coumarin, Xanthene, acridine, thiazole, thiazine, oxazine, azine, aminoketone, Methine and polymethine dyes, porphyrins, aminotriarylmethanes, Called merocyanines, squarylium and pyridinium dyes. you are sensitive especially to radiation in the range of 350 to 700 nm. For radiation in the near IR range (700 to 1200 nm) is the Sensitivity, however, only low.

Also in EP-A 0 315 988 is a photopolymerizable Mixture disclosed for radiation in the range of 600 to 700 nm is sensitive. It comprises a polymerizable, ethylenic unsaturated compound, a radical generator and a substituted one 2-phenyl-2H-naphtho [6,5,4-a, m, n] thioxanthene-1,3-dione or a substituted 3-alkoxy-2-phenyl-naphtho [6,5,4-a, m, n] thioxanthen-1-one as a sensitizer.

The subject of EP-A-0 441 524 is one upon irradiation crosslinking composition with a polymer to which mono-, di- or trihalomethyl-substituted [1,3,5] triazine residues via a Bridge group are covalently bonded. The base polymer may be made a variety of polymers are selected. It can For example, a polyamide, a polyester, a polyurethane, a Polysiloxane, a phenolic resin, a polystyrene, a polyacrylate, a Polyacrylic acid, a polyacrylamide, a polyacrylonitrile, a Polyethylene, a polybutadiene, polyvinylpyrrolidone, polycaprolactone, Gelatin, starch or a polysaccharide.

In EP-A 0 563 925 is a photopolymerizable mixture discloses a radically polymerizable monomer substituted 2-phenyl-4-halomethyl (or 4,6-bis-halomethyl) - [1,3,5] triazine and a compound known as Sensitizer for the triazine. The mixture is used for the production of negative-working printing plates.

A directly imageable recording material for the production of planographic printing plates is described in EP-A 1,106,381. It comprises an electrochemically roughened carrier of a special aluminum alloy and a photosensitive layer, an IR absorber and a water-insoluble, but alkali-soluble contains polymeric binder.

The directly imageable with UV, VIS or IR laser beams Recording material for the production of offset printing plates according to EP-A 1 091 247, a photosensitive layer comprises a monomer with one or more polymerisable, substituted acrylate group (s) or derivatives thereof and a Photopolymerization initiator contains. In the α-position to polymerizable double bond of the monomer is always a Heteroatom or a halogen atom. Preferred initiators are aromatic ketones, aromatic onium salts, organic peroxides, Hexaarylbiimidazole, borates, metallocenes and compounds with Carbon-halogen bonds. The latter also count optionally further substituted [1,3,5] triazines with TrihalogenmethylGruppen. The photosensitive layer may be next to it Sensitizer dyes included. On the photosensitive Layer may additionally be a polyvinyl alcohol layer. A major disadvantage of this recording material is in that the monomers are synthetically difficult to access and thus are correspondingly expensive. Furthermore, the reactivity and so that the photosensitivity of the layer is reduced.

EP-A-1 176 007 and EP-A-1 162 078 describe a radiation-sensitive A mixture comprising a free-radically polymerizable (meth) acrylate monomer having at least two (Meth) acrylate groups and at least one photooxidizable group, a Radical initiator, an IR-absorbing heptamethine cyanine dye, and an organic contains polymeric binder. The radical initiator absorbs near infrared radiation.

It was therefore the task of a radiation-sensitive To provide a mixture as well as a recording material, the easily accessible, preferably commercially available Containing monomers and one over the prior art has improved photosensitivity.

The problem is solved with a radiation-sensitive Mixture absorbing one in the range of 700 to 1200 nm Heptamethine cyanine dye contains and acrylate and / or Methacrylate monomers having at least one photooxidizable group.

The subject of the present invention is accordingly a radiation-sensitive mixture containing a radical polymerizable acrylate or methacrylate monomer and / or oligomer with at least two acrylate and / or meth-acrylate groups and at least one photooxidizable group, a photoinitiator, an IR absorbing dye and an organic polymer Contains binder, and characterized in that the IR-absorbing Dye is a heptamethine cyanine dye, that the mixture is sensitive to the near infrared region, and the photoinitiator does not absorb this radiation.

Preference is given to heptamethine cyanine dyes in which 3 Methine carbon atoms part of a 5- to 7-membered isocyclic or heterocyclic ring. The name "Heptamethine cyanine dyes" includes amphoteric as well as ionic Connections. The aromatic end groups in the dyes are preferably indole or indolium groups, to which, if appropriate still more rings, especially carbocyclic rings, fused could be.

The binder can be made from a whole range of organic Be selected polymers. Also mixtures of different binders can be used. Suitable examples are chlorinated Polyalkylenes (especially chlorinated polyethylene and chlorinated Polypropylene), poly (meth) acrylic acid alkyl ester or alkenyl ester (in particular polymethyl (meth) acrylate, polyethyl (meth) acrylate, Polybutyl (meth) acrylate, polyisobutyl (meth) acrylate, Polyhexyl (meth) acrylate, poly [(2-ethyl-hexyl) - (meth) acrylate] and Poly [allyl (meth) acrylate]), copolymers of (meth) acrylic acid alkyl esters or alkenyl esters with other copolymerisable Monomers (in particular with (meth) acrylonitrile, vinyl chloride, Vinylidene chloride, styrene and / or butadiene), polyvinyl chloride (PVC), Vinyl chloride / acrylonitrile copolymers, polyvinylidene chloride (PVDC), Vinylidene chloride / acrylonitrile copolymers, polyvinyl acetate, Polyvinyl alcohol, polyacrylonitrile, acrylonitrile / styrene copolymers, (Meth) acrylamide / alkyl (meth) acrylate copolymers, Acrylonitrile / butadiene / styrene (ABS) terpolymers, polystyrene, poly (α-methyl-styrene), Polyamides, polyurethanes, polyesters, methylcellulose, Ethyl cellulose, acetyl cellulose, (hydroxy (C 1 -C 4) alkyl) cellulose, Carboxymethyl cellulose, polyvinyl formal and polyvinyl butyral. Particularly suitable are binders which are insoluble in water, in aqueous-alkaline solutions, however, soluble or at least swellable are. Appropriately, for such polymers are selected in the usual organic coating solvents are soluble.

For the purposes of the present invention are binders which Contain carboxy groups, particularly suitable. That's in particular Copolymers containing units of α, β-unsaturated carboxylic acids or Dicarboxylic acids (preferably acrylic acid, methacrylic acid, crotonic acid, Vinylacetic acid, maleic acid or itaconic acid). To call are in particular copolymers with units of (meth) acrylic acid and Units of alkyl (meth) acrylates, allyl methacrylates and / or (Meth) acrylonitrile, as well as copolymers with units of Crotonic acid and units of alkyl (meth) acrylates and / or (Meth) acrylonitrile, and finally vinylacetic acid / alkyl (meth) acrylate copolymers. Also suitable are copolymers with Units of maleic anhydride or maleic acid monoalkyl esters. These include, for example, copolymers with units Maleic anhydride and styrene, substituted styrenes, unsaturated ethers or esters or unsaturated aliphatic ones Hydrocarbons, as well as those obtainable from such copolymers Esterification. Also to be mentioned are products from the Reaction of hydroxyl-containing polymers with intramolecular Dicarboxylic anhydrides arise. Under the term "copolymers" here are polymers with units of at least 2 different Monomers are understood, including terpolymers and higher Copolymers. Also useful are polymers in which groups with acidic hydrogen atoms occur, part or all of them with activated isocyanates is reacted. These include, for example Products as used in the reaction of hydroxyl-containing Polymers with aliphatic or aromatic sulfonyl isocyanates or phosphinic isocyanates arise. Well suited Finally, polymers with aliphatic or aromatic Hydroxy groups, for example copolymers with units of Hydroxyalkyl (meth) acrylates, from allyl alcohol, from hydroxystyrene or of vinyl alcohol, and epoxy resins, if they have one carry sufficient number of free OH groups.

The term "(meth) acrylic acid" is related to the present invention for "acrylic acid and / or methacrylic acid". The same applies to (meth) acrylonitrile, - (meth) acrylate, (meth) acrylamide, etc.

The organic polymers used as binders have in general, a mean molecular weight Mw of 600 to 200,000, preferably 1,000 to 100,000. Preference is furthermore given to polymers which an acid number between 10 and 250, preferably from 20 to 200, or a hydroxyl number of 50 to 750, preferably 100 to 500, exhibit.

The proportion of binder (s) is generally 10 to 90 wt .-%, preferably 20 to 80 wt .-%, each based on the total weight the non-volatile components of the radiation-sensitive Mixture.

The radically polymerizable acrylate or methacrylate compound with at least one photooxidizable group For example, a connection with a primary, secondary and in particular tertiary amino group. Particularly preferred polymerizable compounds which are next to a (tertiary) Amino group still at least one urea and / or urethane group contain. By the term "urea group" is meant in context with the present invention, a group of the formula> N-CO-N < be understood, in which the valencies on the nitrogen atoms with Hydrogen atoms or hydrocarbon radicals are saturated (It should not have more than one valence on each of them Nitrogen atoms are saturated with a hydrogen atom). It is but also possible that a valence on a nitrogen atom the Binding to a carbamoyl group (i.e., a -CO-NH group) producing a biuret structure.

Q

für -S-,

R

für eine (C₂-C₈)Alkyl-, (C₂-C₈)Hydroxyalkyl- oder (C₆-C₁₄)-Aryl-gruppe,

R¹ und R²

unabhängig voneinander für ein Wasserstoffatom, eine Alkyl- oder Alkoxyalkylgruppe und

R³

für ein Wasserstoffatom, eine Methyl- oder Ethylgruppe steht,

X¹

eine geradkettige oder verzweigte, gesättigte Kohlenwasserstoffgruppe mit 1 bis 12 Kohlenstoffatomen ist,

X²

eine (c+1)wertige Kohlenwasserstoffgruppe darstellt, in der bis zu 5 Methylengruppen durch Sauerstoffatome ersetzt sein können,

D¹ und D²

unabhängig voneinander eine gesättigte Kohlenwasserstoffgruppe mit 1 bis 5 Kohlenstoffatomen bedeuten,

E

eine zweiwertige gesättigte Kohlenwasserstoffgruppe mit 2 bis 12 Kohlenstoffatomen, eine zweiwertige 5- bis 7-gliedrige, gesättigte, iso- oder heterocyclische Gruppe, wobei die heterocyclische Gruppe bis zu 2 Stickstoff-, Sauerstoff- und/oder Schwefelatome im Ring enthalten kann, eine zweiwertige, aromatische, mono- oder bicyclische, isocyclische Gruppe mit 6 bis 12 Kohlenstoffatomen oder eine zweiwertige 5- oder 6-gliedrige aromatische heterocyclische Gruppe darstellt,

a

eine ganze Zahl von 0 bis 4,

b

0 oder 1,

c

eine ganze Zahl von 1 bis 3,

m

eine ganze Zahl von 2 bis 4 und

n

eine ganze Zahl von 1 bis m ist

.In addition, compounds are suitable which have a photooxidizable amino, urea or thio group, which may also be part of a heterocyclic ring. Compounds with photooxidizable enol groups are also possible. Concrete examples of photooxidizable groups are triethanolamino, triphenylamino, thiourea, imidazole, oxazole, thiazole, acetylacetonyl, N-phenyl-glycine and ascorbic acid groups. Particularly suitable monomers with photooxidizable groups can be defined by the following formula I R _(mn) Q [(-CH ₂ -CR ¹ R ² -O) _a -CO-NH- (X ¹ -NH-CO-O) _b -X ² - (O-CO-CR ³ = CH ₂ ) _c ] _n describe in which

Q

for -S-,

R

for a (C ₂ -C ₈ ) alkyl, (C ₂ -C ₈ ) hydroxyalkyl or (C ₆ -C ₁₄ ) aryl group,

R ¹ and R ²

independently represent a hydrogen atom, an alkyl or alkoxyalkyl group and

R ³

represents a hydrogen atom, a methyl or ethyl group,

X ¹

is a straight-chain or branched, saturated hydrocarbon group having 1 to 12 carbon atoms,

X ²

represents a (c + 1) -valent hydrocarbon group in which up to 5 methylene groups may be replaced by oxygen atoms,

D ¹ and D ²

independently of one another denote a saturated hydrocarbon group having 1 to 5 carbon atoms,

e

a divalent saturated hydrocarbon group having 2 to 12 carbon atoms, a divalent 5- to 7-membered, saturated, iso or heterocyclic group, wherein the heterocyclic group may contain up to 2 nitrogen, oxygen and / or sulfur atoms in the ring, a divalent one represents an aromatic, mono- or bicyclic, isocyclic group having 6 to 12 carbon atoms or a divalent 5- or 6-membered aromatic heterocyclic group,

a

an integer from 0 to 4,

b

0 or 1,

c

an integer from 1 to 3,

m

an integer from 2 to 4 and

n

is an integer from 1 to m

,

Compounds of this type and processes for their preparation are described in detail in EP-A 0 287 818. If a plurality of radicals R or several radicals of the structure given in the square brackets are present in a compound of the general formula I, ie if (mn)> 1 or n> 1, then these radicals may be identical or different. Compounds of the formula I in which n = m are particularly preferred. All radicals then contain polymerizable groups. Preferably, the running number a = 1, with several residues a = 0 should occur in no more than one remainder. When R is an alkyl or hydroxyalkyl group, it generally comprises 2 to 8, especially 2 to 4, carbon atoms. Aryl radicals R are generally mono- or binuclear, but preferably mononuclear. They may be substituted by (C ₁ -C ₅ ) alkyl or (C ₁ -C ₅ ) alkoxy groups. When R ¹ and R ^{2 are} alkyl or alkoxy groups, they preferably contain 1 to 5 carbon atoms. R ³ is preferably a hydrogen atom or a methyl group. X ¹ is preferably a straight-chain or branched aliphatic and / or cycloaliphatic radical having preferably 4 to 10 carbon atoms. X ² comprises in a preferred embodiment 2 to 15 carbon atoms. In particular, it is a saturated, straight-chain or branched aliphatic and / or cycloaliphatic radical having this number of carbon atoms. Up to 5 methylene groups in these radicals may be replaced by oxygen atoms. X ² consists of pure hydrocarbon chains, the radical generally comprises 2 to 12, preferably 2 to 6 carbon atoms. X ² may also be a cycloaliphatic group having 5 to 10 carbon atoms, in particular a cyclohexanediyl group. The saturated heterocyclic ring formed by D ¹ , D ² and the two nitrogen atoms generally comprises 5 to 10 ring members, in particular 6 ring members. Accordingly, in the latter case, the heterocyclic ring is preferably a piperazine and the radical derived therefrom is a piperazine-1,4-diyl radical. The moiety E in a preferred embodiment is an alkanediyl group, usually comprising about 2 to 6 carbon atoms. The bivalent 5- to 7-membered, saturated, isocyclic group E is preferably a cyclohexanediyl, in particular a cyclohexane-1,4-diyl group. The divalent isocyclic aromatic group E is preferably an ortho, meta or para-phenylene group. Finally, the divalent 5- or 6-membered aromatic heterocyclic group E preferably contains nitrogen and / or sulfur atoms in the heterocyclic ring. c is preferably 1, ie each of the radicals in the square bracket generally contains only one polymerisable group, in particular only one (meth) acryloyloxy group.

The compounds of the formula I where b = 1, which accordingly two Urethane groups in each of the radicals indicated in the square brackets can be prepared in a conventional manner by reaction of acrylic acid esters or alkacrylates, which contain free hydroxy groups, with equimolar amounts of Diisocyanates. Excess isocyanate groups are then for example, tris- (hydroxyalkyl) -amines, N, N'-bis-hydroxyalkylpiperazines or N, N, N ', N'-tetrakis-hydroxyalkylalkylenediamines reacted, respectively individual hydroxyalkyl groups by alkyl and / or aryl groups R can be replaced. In case a = 0 there is a urea grouping in front. Examples of those used as starting materials Hydroxyalkylamines are diethanolamine, triethanolamine, tris- (2-hydroxy-propyl) -amine, Tris (2-hydroxybutyl) amine and alkyl bishydroxyalkyl amines. Examples of suitable diisocyanates are Hexamethylene diisocyanate, 2,2,4-trimethyl-hexamethylene-diisocyanate, 1,4-cyclohexylene diisocyanate (= 1,4-diisocyanato-cyclohexane) and 1,1,3-trimethyl-3-isocyanatomethyl-5-isocyanato-cyclohexane. When Hydroxy-containing esters are preferably hydroxyethyl (meth) acrylate, Hydroxypropyl (meth) acrylate and hydroxyisopropyl (meth) acrylate used.

Allow polymerizable compounds of formula I with b = 0 establish themselves by the already described Hydroxyalkylaminoverbindungen are reacted with isocyanate groups containing acrylic or alkacrylic acid esters. As isocyanate groups containing ester is thereby preferably (2-isocyanato-ethyl) - (meth) acrylate used.

The compounds of formula II are analogous to those of Formula I prepared, instead of from reaction products Hydroxyalkyl acrylates or alkacrylates and diisocyanates the corresponding acrylic acid or alkacrylic acid glycidester used become. Such compounds and processes for their preparation are otherwise disclosed in EP-A 0 316 706.

Polymerizable compounds with photooxidizable groups of the formula II R _(mn) Q [(-CH ₂ -CR ¹ R ² -O) _{a '} - (CH ₂ -CH [CH ₂ O-CO-CR ³ CHCH ₂ ] -O) _b' -H] _n are suitable for the purposes of the present invention, when a 'and b' are integers from 1 to 4 and Q, R, R ¹ , R ² , R ³ , n and m have the meanings given above, wherein Q additionally a group of the formula>N-E'-N<, in which the radical E 'of the formula III -CH ₂ -CH (OH) -CH ₂ - [O- (p) C ₆ H ₄ -C (CH ₃ ) ₂ - (p) C ₆ H ₄ -CH ₂ -CH (OH) -CH ₂ -] _c where c has the same meaning as in formula I and (p) C ₆ H _{4 is} para-phenylene.

X^1' für -C_iH_2i - oder -C_iH_2i-1-O-CO-NH(-X¹-NH-CO-O)_b-X²-O-CO-CR³=CH₂ steht,

D³ eine gesättigte Kohlenwasserstoffgruppe mit 4 bis 8 Kohlenstoffatomen, die mit dem Stickstoffatom einen 5- oder 6-gliedrigen Heterocyclus bildet,

Z ein Wasserstoffatom oder einen Rest der Formel C_kH_2k-O-CO-NH(-X¹-NH-CO-O)_b-X²-O-CO-CR³=CH₂ darstellt,

i und k unabhängig voneinander ganze Zahlen von 1 bis 12 sind und

n' eine ganze Zahl von 1 bis 3 ist,

wobei in mindestens einem der an Q gebundenen Reste a = 0 ist.Acrylic and alkacrylic acid esters of the formula IV can also be used as the polymerizable compounds with photooxidizable groups Q '[(-X ^1' -CH ₂ -O) _a -CO-NH (-X ¹ -NH-CO-O) _b -X ² -O-CO-CR ³ = CH ₂ ] _n where Q '=

X ^{1 'is} -C _i H _2i - or -C _i H _2i-1 -O-CO-NH (-X ¹ -NH-CO-O) _b -X ² -O-CO-CR ³ = CH ₂ .

D ^{3 is} a saturated hydrocarbon group having 4 to 8 carbon atoms which forms a 5- or 6-membered heterocycle with the nitrogen atom,

Z represents a hydrogen atom or a radical of the formula C _k H _2k -O-CO-NH (-X ¹ -NH-CO-O) _b -X ² -O-CO-CR ³ = CH ₂ ,

i and k are independently integers from 1 to 12 and

n 'is an integer from 1 to 3,

wherein in at least one of the radicals bonded to Q a = 0.

X ¹ , R ³ , a and b in the formula IV have the abovementioned meaning; X ² represents a divalent hydrocarbon group in which up to 5 methylene groups may be replaced by oxygen atoms. The running number a in this formula is preferably 0 or 1; i is preferably a number from 2 to 10. Preferred radicals Q are piperazine-1,4-diyl (D ¹ = D ² = CH ₂ -CH ₂ ), piperidin-1-yl (D ³ = [CH ₂ ] ₅ , Z = H) and 2- (2-hydroxy-ethyl) -piperidin-1-yl (D ³ = [CH ₂ ] ₅ , Z = CH ₂ -CH ₂ OH).

Of the compounds of the formula IV, preference is given to those which in addition to a urea group at least one urethane group contain. Under "urea group" in turn should already continue Group of the formula> N-CO-N <described above. Compounds of formula IV and processes for their preparation are disclosed in EP-A 0 355 387.

As polymerizable compounds with photooxidizable groups are also reaction products of mono- or diisocyanates with polyhydric alcohols in which all or part of the Hydroxy groups are esterified with (meth) acrylic acid suitable. Preference is given to products as they result from the implementation of Hydroxyalkyl (meth) acrylates with diisocyanates arise. Such Monomers are known and, for example, in DE-A 28 22 190 or DE-A 20 64 079 described.

The mixture according to the invention can moreover photopolymerizable acrylate and / or alkacrylate compounds with 2 or more, preferably 3 to 6, acrylate and / or alkacrylate, especially methacrylate groups. This multifunctional Compounds act as crosslinkers. Preferred crosslinkers are (Meth) acrylates of saturated aliphatic or alicyclic, trihydric or polyhydric alcohols, such as alkanediols (especially Ethylene glycol and propylene glycol), bis-phenol-A, trimethylolethane, Trimethylolpropane, pentamethylolpropane, pentaerythritol or Dipentaerythritol. These are, for example, ethoxylated and propoxylated trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, Tris (2-hydroxyethyl) -isocyanurattri (meth) acrylate or glycerol tri (meth) acrylate. Of the Proportion of crosslinking acrylate and / or Alkacrylate compounds are generally up to 20% by weight, preferably 5 to 15 wt .-%, each based on the total weight of non-volatile constituents of the radiation-sensitive mixture.

The proportion of all photopolymerizable monomers or oligomers is generally from 10 to 85% by weight, preferably from 20 to 75% by weight, in each case based on the total weight of the non-volatile Components of the radiation-sensitive mixture. There are generally at least 40% by weight of the photopolymerizable monomers and / or oligomers such with photooxidizable groups.

R¹=R²=H oder R¹ und R² zusammen -CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet,

R³=Methyl, Ethyl, Propyl oder Butyl

X= -(CH₂)₃- oder -(CH₂)₂-

Y=

R¹=R²=H oder R¹ und R² zusammen -CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet,

R³=Methyl, Ethyl, Propyl oder Butyl

R⁴=H, Cl,

X= -(CH₂)₃- oder (CH₂)₂-

Y= Br^-, Cl^-, I^-, pTosO^-, ClO₄ ^-, BF₄ ^- oder PF₆ ^-

The heptamethine cyanine dye preferably corresponds to one of the general formulas V or VI.

R ¹ = R ² = H or R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring,

R ³ = methyl, ethyl, propyl or butyl

X = - (CH ₂ ) ₃ - or - (CH ₂ ) ₂ -

Y =

R ¹ = R ² = H or R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring,

R ³ = methyl, ethyl, propyl or butyl

R ⁴ = H, Cl,

X = - (CH ₂ ) ₃ - or (CH ₂ ) ₂ -

Y = Br ^- , Cl ^- , I ^- , pTosO ^- , ClO ₄ ^- , BF ₄ ^- or PF ₆ ^-

Structure and nomenclature of cyanine dyes are u. a. at H. Zollinger, Color Chemistry, VCH, Weinheim 1991 Nomenclature described.

The proportion of heptamethine cyanine dye is general 0.01 to 10.0 wt .-%, preferably 0.5 to 8.0 wt .-%, each based on the total weight of the nonvolatile constituents of the photopolymerizable mixture.

The used in the mixture according to the invention Photoinitiators are known per se. Well suited are triazine compounds with at least one photocleavable Trihalogenmethylgruppe, in particular a trichloro or Tribromomethyl. The trihalomethyl groups can thereby directly, via a conjugated double bond or via a chain of conjugated double bonds to an aromatic carbocyclic or heterocyclic ring. Preference is given to compounds with a triazine base to the particular 2 Trihalogenmethylgruppen are bound. Such compounds are for example in DE 2 718 259, EP-A 0 137 452 and in EP-A 0 563,925. Basically absorb the used Triazines do not use the radiation used for imaging. Therefore also Trihalogenmethyltriazine can be used, whose Own absorption is below 300 nm. Such materials are particularly preferred, because thereby the photoreactivity towards the usual interior lighting is reduced. usable Trihalomethyltriazines are, for example, those which are (saturated) aliphatic substituents or unsaturated substituents with only a few extended mesomeric Π-electron systems contain. Compounds with other skeletons, for example Phenyltrihalogenomethyl-sulfones (especially phenyltribromomethylsulfone) and phenyl-trihalogeno-methyl-ketones, which are in the shorter-wavelength Absorb UV range, are in principle also usable. Of the Proportion of photoinitiator (s) is generally from 0.1 to 20 wt .-%, preferably 1.0 to 10 wt .-%, each based on the total weight the non-volatile constituents of the photopolymerizable Mixture.

Optionally present predispersed phthalocyanine pigments serve primarily for coloring the mixture and the layers produced with it. Their share is generally about 1 to 20 wt .-%, preferably about 2 to 14 wt .-%. Particularly suitable Pre-dispersed phthalocyanine pigments are described in DE-A 199 15 717 and DE-A 199 33 139 discloses. Preferred are in particular metal-free phthalocyanine pigments.

To the properties of the photopolymerizable layer still better to adapt to the respective uses, this can still contain other additives. These are, for example, additives that inhibit thermally induced polymerization, hydrogen donors, Dyes, colored and colorless pigments, color formers, Filter dyes, indicator dyes, plasticizers and / or Chain transfer agent. As additives are suitably selected those that do not absorb the imagewise acting radiation.

For the preparation of the recording material according to the invention the radiation-sensitive mixture is useful in a dissolved or dispersed organic solvent and the solution or Dispersion applied as a thin film on the support. The Can be applied by pouring, spraying, dipping, by applying with the help of rollers or similar, known in the art Procedure done. After drying in this way Receive recording material from which, for example Printing forms for high-pressure, planographic, gravure or screen printing let produce. It can also be a material that makes up Relief copies (for example for the production of texts in Braille), single copies, Gerbbilder, Pigmentbilder or similar to produce image-structured products. The mixture according to the invention is also suitable for the production of Ätmreservagen, for example, in the production of Printed circuit boards or name tags can be used, as well as for molding. However, it is preferably used for Production of photoresist layers and printing plates.

The present invention is accordingly also a Recording material for the production of printing plates with a Carrier and a layer of the invention photopolymerizable mixture. As carrier material for printing plates are films, tapes or plates made of metal (in particular made of aluminum or an aluminum alloy, steel, zinc or Copper) or plastic (especially polyester - specifically Polyethylene terephthalate or cellulose acetate), for screen printing media also perlon gauze. In many cases it is convenient to the surface of the Carrier of a mechanical, chemical and / or electrochemical To undergo pretreatment to the adhesion between the carrier and optimal radiation-sensitive layer or adjust to achieve that the carrier surface the image-wise acting Radiation less reflected (antihalation). The preferred one Support for offset printing plates is made of aluminum or an Al alloy and is electrochemically roughened on its surface, then anodized, optionally also with a hydrophilicizing agent (for example Polyvinylphosphonic acid).

As a result of the sensitivity of the recording material according to the invention in the near infrared (NIR) range, the IR laser sources familiar to the person skilled in the art between 700 and 1200 nm are used for imagewise radiation. Preference is given to laser diodes which emit in the NIR range.
The novel recording material has a particularly high imaging performance and is therefore particularly suitable for digital imaging with NIR laser beams. In the subsequent development process is then differentiated exactly between non-image areas and image locations, so that the dot gain is surprisingly significantly reduced. Even small negative fonts are therefore still clearly reproduced. At the same time, the material has a very high sensitivity in the NIR wavelength range.

It is practically essential to protect the radiation-sensitive layer from atmospheric oxygen during NIR-induced polymerization. This is most easily achieved by a covering layer which is impermeable to oxygen or only slightly permeable ("poorly permeable" means a permeability of not more than 100 cm ³ O ₂ / m ² * d * bar, determined in accordance with DIN 53 380 at 23 ° C. ) applied to the radiation-sensitive layer. The cover layer may be self-supporting and be stripped before the subsequent development step. It then consists for example of a laminated polyester film. Also, overcoats of a material that is soluble or dispersible (at least in the uncured areas) in the developer liquid may be used. Suitable materials for a cover layer which is completely soluble in aqueous alkaline developers are, for example, polyvinyl alcohol, polyvinylpyrrolidone, polyphosphates, sugars, etc. The thickness of the cover layer is generally 0.1 to 10 .mu.m, preferably 1 to 5 .mu.m.

Further processing of imagewise irradiated Recording materials according to common and the Specialist known methods. This can be imagewise before developing irradiated material can still be reheated to a better To achieve networking in the irradiated areas. To develop even organic solvents or mixtures of organic Solvents are used, but are preferably aqueous alkaline Solutions with a pH of 8 to 14, in particular of 9 to 13, up to about 20% by weight, preferably up to about 15% by weight, may contain water-miscible organic solvents. The Developers can also wetting agents, dyes, salts and / or other additives. When developing the unirradiated areas of the layer removed while the irradiated and thus cured areas of the layer on the support remain.

The following examples illustrate the invention. "Gt" where it stands for "part by weight (s)", "Vt" means "part by volume (s)". Percentages are by weight unless otherwise stated or out of context.

example 1

6,92 Gt

einer 32,8 %igen Lösung eines Methylmethacrylat-/Methacrylsäure-Copolymers (Molverhältnis von Methylmethacrylat- zu Methacryl-säure-Einheiten 4:1; Säurezahl: 110 mg KOH/g) in 2-Butanon (Viskosität der Lösung: 105 mm²/s mit Kapillarengröße 1,0 bei 25°C),

3,77 Gt

einer 86,8 %igen Lösung eines Reaktionsproduktes aus 1 mol 2,2,4-Trimethyl-hexamethylendiisocyanat und 2 mol Hydroxyethyl-methacrylat (Viskosität: 3,3 mm²/s mit Kapillarengröße 1,0 bei 25°C),

0,16 Gt

IR-Farbstoff FEW S0094 (= Formel VI, R¹ und R² zusammen -CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet, R³ = CH₃, R⁴ = Cl, X = (CH₂)₃ und Y^- = pTosO^-,

6,87 Gt

Heliogenblau D 7490-Farbstoffdispersion (vgl. DE 199 33 139 A1) (9,9 %ig, Viskosität 7,0 mm²/s mit Kapillargröße 1 bei 25°C),

0,41 Gt

2,4-Bis-trichlormethyl-6-diphenyl-4-yl-[ 1,3,5]triazin,

0,68 Gt

Edaplan™ LA 411 (1 %ig in ®Dowanol PM),

20,5 Gt

2-Butanon und

40,7 Gt

Propylenglykolmonomethylether (®Dowanol PM)

wurde auf einen elektrochemisch aufgerauhten, anodisierten (Oxidgewicht 3 g/m²) und mit Polyvinylphosphonsäure hydrophilierten Aluminium-Druckplattenträger aufgeschleudert und bei 100°C 2 min im Umlufttrockenschrank getrocknet. Die Schichtdicke der strahlungsempfindlichen Schicht betrug dabei 1,58 g/m². Auf die strahlungsempfindliche Schicht wurde eine 6 %ige wäßrige Lösung eines Gemisches aus 1 Gt vollverseiften Polyvinylalkohol (Hydrolysegrad 98,4 %, Viskosität 4 mPa s in 4 %iger wäßrigen Lösung bei 20°C), aus 1 Gt teilverseiften Polyvinylalkohol (Hydrolysegrad 87,7 %, Viskosität 8 mPa s in 4 %iger wäßriger Lösung bei 20°C) und 0,5 Gt Polyvinylpyrrolidon (k-Wert = 30) aufgebracht und ebenfalls 2 min bei 100°C in Umluft getrocknet. Die Deckschicht wies ein Schichtgewicht von 1,47 g/m² auf.A mixture of

6,92 Gt

a 32.8% solution of a methyl methacrylate / methacrylic acid copolymer (molar ratio of methyl methacrylate to methacrylic acid units 4: 1, acid number: 110 mg KOH / g) in 2-butanone (viscosity of the solution: 105 mm ² / s with capillary size 1.0 at 25 ° C),

3.77 Gt

a 86.8% strength solution of a reaction product of 1 mol of 2,2,4-trimethyl-hexamethylene diisocyanate and 2 mol of hydroxyethyl methacrylate (viscosity: 3.3 mm ² / s with capillary size 1.0 at 25 ° C.),

0.16 Gt

IR dye FEW S0094 (= formula VI, R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring, R ³ = CH ₃ , R ⁴ = Cl , X = (CH ₂ ) ₃ and Y ^- = pTosO ^- ,

6,87 Gt

Heliogen blue D 7490 dye dispersion (see DE 199 33 139 A1) (9.9% strength, viscosity 7.0 mm ² / s with capillary size 1 at 25 ° C.),

0.41%

2,4-bis-trichloromethyl-6-diphenyl-4-yl- [1,3,5] triazine,

0.68 Gt

Edaplan ™ LA 411 (1% in ®Dowanol PM),

20.5 Gt

2-butanone and

40.7 Gt

Propylene glycol monomethyl ether (®Dowanol PM)

was spun on an electrochemically roughened, anodized (oxide weight 3 g / m ² ) and hydrophilized with polyvinylphosphonic aluminum pressure plate carrier and dried at 100 ° C for 2 min in a convection oven. The layer thickness of the radiation-sensitive layer was 1.58 g / m ² . A 6% strength aqueous solution of a mixture of 1% by weight polyvinyl alcohol (degree of hydrolysis 98.4%, viscosity 4 mPa s in 4% strength aqueous solution at 20 ° C.) was applied to the radiation-sensitive layer, 1 part by weight polyvinyl alcohol (degree of hydrolysis 87, 7%, viscosity 8 mPa s in 4% aqueous solution at 20 ° C) and 0.5 pbw polyvinylpyrrolidone (k value = 30) and also dried for 2 min at 100 ° C in circulating air. The cover layer had a coating weight of 1.47 g / m ² .

The printing plate thus obtained was imaged with a CREO Trendsetter 3244T (2400 dpi), heated for 1 min at 100 ° C and then with an aqueous-alkaline developer (Agfa EN 231C) at 28 ° C at a flow rate of 1 m / min. (Agfa VSP85). The indicated sensitivity corresponded to that laser energy in the image plane which was required to make a 50% field formed of 1x1 and 8x8 pixels appear bright. The value determined in this way was 18 mJ / cm ² .

Example 2 and Comparative Examples V1 to V4

A

eine 32,8 %ige Lösung eines Methylmethacrylat/Methacrylsäure-Copolymers (Molverhältnis von Methylmethacrylat- zu Methacrylsäure-Einheiten 4:1; Säurezahl: 110 mg KOH/g) in 2-Butanon (Viskosität 105 mm²/s bei Kapillarengröße 1,0 und 25°C)

B

eine 86,8 %ige Lösung eines Reaktionsproduktes aus 1 mol 2,2,4-Trimethyl-hexamethylendiisocyanat und 2 Mol Hydroxyethylmethacrylat (Viskosität 3,3 mm²/s bei Kapillarengröße 1,0 und 25°C)

C

Dipentaerythritpentaacrylat (Cray Valey SR 399)

D

ethoxyliertes Trimethylolpropantriacrylat (Cray Valey SR 454)

E

Trimethylolpropantriacrylat

F

Bisphenol-A-dimethacrylat

G

R-Farbstoff FEW S0094 (= Formel VI, R¹ und R² zusammen -CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet, R³ = CH₃, R⁴ = Cl, X = (CH₂)₃ und Y^- =pTosO^- (= para-toluolsulfonat))

H

Heliogenblau D 7490-Farbstoffdispersion (vgl. DE 199 33 139 A1) (9,9 %ig, Viskosität 7,0 mm²/s mit Kapillargröße 1,0 bei 25°C)

I

2,4-Bis-trichlormethyl-6-diphenyl-4-yl-[1,3,5]triazin

J

2-Mercapto-benzothiazol

K

Edaplan™ LA 411 (1 %ig in ®Dowanol PM)

L

2-Butanon

M

Propylenglykol-monomethylether (®Dowanol PM)

As described in Example 1, further printing plates were produced, the following components being used for the IR-sensitive layer:

A

a 32.8% solution of a methyl methacrylate / methacrylic acid copolymer (molar ratio of methyl methacrylate to methacrylic acid units 4: 1, acid number: 110 mg KOH / g) in 2-butanone (viscosity 105 mm ² / s at capillary size 1.0 and 25 ° C)

B

a 86.8% solution of a reaction product of 1 mole of 2,2,4-trimethyl-hexamethylene diisocyanate and 2 moles of hydroxyethyl methacrylate (viscosity 3.3 mm ² / s at capillary size 1.0 and 25 ° C)

C

Dipentaerythritol pentaacrylate (Cray Valey SR 399)

D

ethoxylated trimethylolpropane triacrylate (Cray Valey SR 454)

e

trimethylolpropane

F

Bisphenol A dimethacrylate

G

R dye FEW S0094 (= formula VI, R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring, R ³ = CH ₃ , R ⁴ = Cl , X = (CH ₂ ) ₃ and Y ^- = pTosO ^- (= para-toluenesulfonate))

H

Heliogen blue D 7490 dye dispersion (see DE 199 33 139 A1) (9.9% strength, viscosity 7.0 mm ² / s with capillary size 1.0 at 25 ° C.)

I

2,4-bis-trichloromethyl-6-diphenyl-4-yl- [1,3,5] triazine

J

2-mercaptobenzothiazole

K

Edaplan ™ LA 411 (1% in ®Dowanol PM)

L

2-butanone

M

Propylene glycol monomethyl ether (®Dowanol PM)

The particular composition used, layer weights and specific plate sensitivity are listed in Table 1: component Examples 2 V1 V2 V3 V4 Gt Gt Gt Gt Gt A 6,900 6,904 6,904 6,904 6,904 B 3,770 - - - - C - 3,270 - - - D - - 3,270 - - e - - - 3,270 - F - - - - 3,270 G 0.163 0.163 0.163 0.163 0.163 H 6,870 6.869 6.869 6.869 6.869 I 0.408 0.408 0.408 0.408 0.408 J 0,007 0,007 0,007 0,007 0,007 K 0,680 0.679 0.679 0.679 0.679 L 20.48 20.98 20.98 20.98 20.98 M 40.72 40.72 40.72 40.72 40.72 Coating weight [g / m ² ] 1.60 1.50 1.50 1.30 1.50 Energy value [mJ / cm ² ] 42 109 - 117 90

Example 3

2,92 Gt

einer 32,8 %igen Lösung eines Methylmethacrylat/Methacrylsäure-Copolymers (Molverhältnis von Methylmethacrylat- zu Methacrylsäure-Einheiten 4:1; Säurezahl: 110 mg KOH/g) in 2-Butanon (Viskosität 105 mm²/s bei Kapillarengröße 1,0 und 25°C),

6,99 Gt

einer 28,9 %igen Lösung eines Reaktionsproduktes aus 1 mol Hexamethylendiisocyanat, 1 mol Hydroxyethylmethacrylat und 0,5 mol 2-(2-Hydroxyethyl)-piperidin (Viskosität 1.7 mm²/s mit Kapillarengröße 1,0 bei 25°C),

0,10 Gt

IR-Farbstoff FEW S0094 (= Formel VI, R¹ und R² zusammen -CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet, R³ = CH₃, R⁴=Cl, X=(CH₂)₃ und Y^- = pTosO^-),

3,37 Gt

Heliogenblau D 7490-Farbstoffdispersion (vgl. DE 199 33 139 A1) (9,9 %ig, Viskosität 7,0 mm²/s mit Kapillargröße 1,0 bei 25°C),

0,41 Gt

2,4-Bis-trichlormethyl-6-diphenyl-4-yl-[1,3,5]triazin,

0,67 Gt

Edaplan™ LA 411 (1 %ig in ®Dowanol PM),

19,4 Gt

2-Butanon und

36,1 Gt

Propylenglykolmonomethylether (®Dowanol PM)

wurde, wie unter Beispiel 1 beschrieben, eine Druckplatte hergestellt. Das Schichtgewicht der IR-empfindlichen Schicht betrug 1,2 g/m². Mit der oben beschriebenen Weiterverarbeitung wurde ein Energiewert von weniger als 20 mJ/cm² erhalten.From a mixture of

2.92 Gt

a 32.8% solution of a methyl methacrylate / methacrylic acid copolymer (molar ratio of methyl methacrylate to methacrylic acid units 4: 1, acid number: 110 mg KOH / g) in 2-butanone (viscosity 105 mm ² / s at capillary size 1.0 and 25 ° C),

6.99 Gt

a 28.9% solution of a reaction product of 1 mol of hexamethylene diisocyanate, 1 mol of hydroxyethyl methacrylate and 0.5 mol of 2- (2-hydroxyethyl) piperidine (viscosity 1.7 mm ² / s with capillary size 1.0 at 25 ° C),

0.10 Gt

IR dye FEW S0094 (= formula VI, R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring, R ³ = CH ₃ , R ⁴ = Cl , X = (CH ₂ ) ₃ and Y ^- = pTosO ^- ),

3.37 Gt

Heliogen blue D 7490 dye dispersion (see DE 199 33 139 A1) (9.9% strength, viscosity 7.0 mm ² / s with capillary size 1.0 at 25 ° C.),

0.41%

2.4 to 6-diphenyl-4-yl bis-trichloromethyl-triazine [1,3,5]

0.67 gt

Edaplan ™ LA 411 (1% in ®Dowanol PM),

19.4 Gt

2-butanone and

36.1 Gt

Propylene glycol monomethyl ether (®Dowanol PM)

was prepared as described in Example 1, a printing plate. The coating weight of the IR-sensitive layer was 1.2 g / m ² . With the further processing described above, an energy value of less than 20 mJ / cm ^{2 was} obtained.

Examples 4 to 8

A

eine 32,8 %ige Lösung eines Methylmethacrylat/Methacrylsäure-Copolymers (Molverhältnis von Methylmethacrylat- zu Methacrylsäure-Einheiten 4:1; Säurezahl: 110 mg KOH/g) in 2-Butanon (Viskosität 105 mm²/s mit Kapillarengröße 1,0 bei 25°C)

B

IR-Farbstoff FEW S0325 (= Formel V, R¹ und R² zusammen-CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet, R³ = CH₃, Y = N-Methylbarbituryl, X = (CH₂)₂)

C

IR-Farbstoff FEW S0507 (= Formel VI, R¹, R² = H, R³ = CH₃, R⁴ = 1-Phenyl-5-thio-[1,2,3,4]tetrazolyl, X = (CH₂)₃ und Y = Chlorid

D

IR-Farbstoff FEW S0331 (= Formel V, R¹ und R² zusammen-CH=CH-CH=CH- bedeuten, wobei R¹ gemeinsam mit R² einen sechgliederigen anellierten Ring bildet, R³ = CH₃, -Y = N-Ethylthiobarbituryl, X = (CH₂)₂)

E

IR-Farbstoff FEW S0382 (= Formel VI, R¹, R² = H, R³ = CH₃, R⁴ = 5-methylsulfanyl-[1,3,4]thiadiazol-2-ylsulfanyl, X = (CH₂)₂ und Y^- = ClO4^-

F

IR-Farbstoff FEW S0367 (= Formel VI, R¹, R² = H, R³ = CH₃, R⁴ = 5-methyl-sulfanyl-[1,3,4]thiadiazol-2-ylsulfanyl, X = (CH₂)₃ und Y^- = ClO₄ ^-

G

eine 86,8 %ige Lösung eines Reaktionsproduktes aus 1 mol 2,2,4-Trimethyl-hexamethylendiisocyanat und 2 Mol 2-Hydroxyethyl-methacrylat (Viskosität 3,3 mm²/s mit Kapillarengröße 1,0 bei 25°C)

H

Heliogenblau D 7490-Farbstoffdispersion (vgl. DE 199 33 139 A1) (9,9 %ig, Viskosität 7,0 mm²/s mit Kapillargröße 1,0 bei 25°C)

I

2,4-Bis-trichlormethyl-6-diphenyl-4-yl-[1,3,5]triazin

J

2-Mercapto-benzothiazol

K

®Edaplan LA 411 (1 %ig in ®Dowanol PM)

L

2-Butanon

M

Propylenglykolmonomethylether (®Dowanol PM)

As described in Example 1, IR-sensitive printing plates were produced from the following components:

A

a 32.8% solution of a methyl methacrylate / methacrylic acid copolymer (molar ratio of methyl methacrylate to methacrylic acid units 4: 1, acid number: 110 mg KOH / g) in 2-butanone (viscosity 105 mm ² / s with capillary size 1.0 at 25 ° C)

B

IR dye FEW S0325 (= Formula V, R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring, R ³ = CH ₃ , Y = N- Methylbarbituryl, X = (CH ₂ ) ₂ )

C

IR dye FEW S0507 (= formula VI, R ¹ , R ² = H, R ³ = CH ₃ , R ⁴ = 1-phenyl-5-thio [1,2,3,4] tetrazolyl, X = (CH ₂ ) ₃ and Y = chloride

D

IR dye FEW S0331 (= formula V, R ¹ and R ² together are -CH = CH-CH = CH-, where R ¹ together with R ² forms a six-membered fused ring, R ³ = CH ₃ , -Y = N Ethyl thiobarbituryl, X = (CH ₂ ) ₂ )

e

IR dye FEW S0382 (= formula VI, R ¹ , R ² = H, R ³ = CH ₃ , R ⁴ = 5-methylsulfanyl- [1,3,4] thiadiazol-2-ylsulfanyl, X = (CH ₂ ) ₂ and Y ^- = ClO4 ^-

F

IR dye FEW S0367 (= formula VI, R ¹ , R ² = H, R ³ = CH ₃ , R ⁴ = 5-methylsulfanyl- [1,3,4] thiadiazol-2-ylsulfanyl, X = (CH ₂ ) ₃ and Y ^- = ClO ₄ ^-

G

a 86.8% solution of a reaction product of 1 mole of 2,2,4-trimethyl-hexamethylene diisocyanate and 2 moles of 2-hydroxyethyl methacrylate (viscosity 3.3 mm ² / s with capillary size 1.0 at 25 ° C)

H

Heliogen blue D 7490 dye dispersion (see DE 199 33 139 A1) (9.9% strength, viscosity 7.0 mm ² / s with capillary size 1.0 at 25 ° C.)

I

2,4-bis-trichloromethyl-6-diphenyl-4-yl- [1,3,5] triazine

J

2-mercaptobenzothiazole

K

®Edaplan LA 411 (1% in ®Dowanol PM)

L

2-butanone

M

Propylene glycol monomethyl ether (®Dowanol PM)

The particular composition used, the layer weights and the particular plate sensitivities are listed in Table 2: component Examples 4 5 6 7 8th Gt Gt Gt Gt Gt A 6,430 6,430 6,430 8,090 8.110 B 0,095 - - - - C - 0,095 - - - D - - 0,101 - - e - - - 0.130 - F - - - - 0,120 G 3,310 3,310 3,310 4,170 4,170 H 6,390 6,290 6,160 7,760 7,760 I 0,238 0,238 0,238 0,300 0,300 J 0,018 0,018 0,018 0,020 0,020 K 0,600 0,600 0,600 0,760 0,760 L 17.67 17.67 17,98 51.04 51.02 M 35.35 35.35 35.48 77.74 77.74 Coating weight [g / m ² ] 1.50 1.50 1.66 1.10 1.10 Energy value [mJ / cm ² ] 28 38 61 43 57

Claims (20)

1. A photosensitive mixture which contains an acrylate or methacrylate monomer and/or oligomer capable of free-radical polymerisation and having at least two acrylate and/or methacrylate groups and at least one photooxidisable group, a photoinitiator, an IR-absorbing dye and an organic polymeric binder, wherein the IR-absorbing dye is a heptamethine cyanine dye, the mixture is sensitive to the near infrared and the photoiniator is not absorbing said radiation.
2. The mixture according to claim 1, wherein 3 methine carbon atoms in the heptamethine chain of the dye are part of a 5- to 7-membered isocyclic or heterocyclic ring.
3. The mixture according to claim 1 or 2, wherein the two aromatic terminal groups in the heptamethine cyanine dyes are indole and/or indolium groups with which optionally at least one further ring may also be fused.
4. The mixture according to any of the claims 1 to 3, wherein the heptamethine cyanine dye corresponds to the formula V

   

   R¹=R²=H or R¹ and R² together represent -CH=CH-CH=CH-, R¹ together with R² forming a six-membered fused ring,
   R³ represents methyl, ethyl, propyl or butyl
   X represents -(CH₂)₃- or -(CH₂)₂-
   Y represents

   

   or to the formula VI

   

   R¹=R²=H or R¹ and R² together represent -CH=CH-CH=CH-, R¹ together with R² forming a six-membered fused ring,
   R³ = methyl, ethyl, propyl or butyl
   R⁴ = H, Cl,

   

   X = -(CH₂)₃- or -(CH₂)₂-
   Y = Br^-, Cl^-, I^-, pTosO^-, ClO₄ ^-, BF₄ ^- or PF₆ ^-.
5. The mixture according to any of the claims 1 to 4, wherein the amount of the heptamethine cyanine dye is 0.01 to 10% by weight, preferably 0.5 to 8.0% by weight, based in each case on the total weight of the non-volatile matter of the mixture.
6. The mixture according to any of the claims 1 to 5, wherein the acrylate or methacrylate monomer capable of free-radical polymerisation contains two acrylate or methacrylate groups.
7. The mixture according to claim 6, wherein the photooxidisable group in the acrylate or methacrylate monomer or oligomer, capable of free-radical polymerisation, is a primary, secondary or tertiary amino group, a urea group, a thio group and/or a urethane group.
8. The mixture according to any of the claims 1 to 7, wherein the amount of all photopolymerisable monomers or oligomers is in general 10 to 85% by weight, preferably 20 to 75% by weight, based in each case on the total weight of the non-volatile matter of the mixture.
9. The mixture according to claim 8, wherein the amount of photopolymerisable monomers or oligomers having photooxidisable groups is at least 40% by weight, based on the total weight of all photopolymerisable monomers and/or oligomers.
10. The mixture according to any of the claims 1 to 9, wherein the photoinitiator contains a triazine compound having at least one trihalomethyl group which can be cleaved photolytically, in particular a trichloromethyl or tribromomethyl group.
11. The mixture according to any of the claims 1 to 10, wherein the amount of photoinitiator(s) is in general 0.1 to 20% by weight, preferably 1.0 to 10% by weight, based in each case on the total weight of the non-volatile matter of the mixture.
12. The mixture according to any of the claims 1 to 11, wherein chlorinated polyalkylenes (in particular chlorinated polyethylene and chlorinated polyproylene), alkyl or alkenyl poly(meth)acrylates (in particular polymethyl (meth)acrylate, polyethyl (meth)acrylate, polybutyl (meth)acrylate, polyisobutyl (meth)acrylate, polyhexyl (meth)acrylate, poly[(2-ethylhexyl) (meth)acrylate] and poly[allyl(meth)acrylate]), alkyl (meth)acrylate/(meth)acrylic acid copolymers, copolymers of alkyl or alkenyl (meth)acrylates with other copolymerisable monomers (in particular with (meth)acrylonitrile, vinyl chloride, vinylidene chloride, styrene and/or butadiene), polyvinyl chloride (PVC), vinyl chloride/acrylonitrile copolymers, polyvinylidene chloride (PVDC), vinylidene chloride/acrylonitrile copolymers, polyvinyl acetate, polyvinyl alcohol, polyacrylonitrile, acrylonitrile/styrene copolymers, (meth)acrylamide/alkyl (meth)acrylate copolymers, acrylonitrile/butadiene/styrene (ABS) terpolymers, polystyrene, poly(α-methylstyrene), polyamides, polyurethanes, polyesters, methylcellulose, ethylcellulose, acetylcellulose, (hydroxy-(C₁-C₄)alkyl)cellulose, carboxymethylcellulose, polyvinylformal and/or polyvinylbutyral and α,β-unsaturated carboxylic or dicarboxylic acids are used as the binder.
13. The mixture according to any of the claims 1 to 12, wherein the binder has an average molecular weight M_w of 600 to 2 000, preferably 1 000 to 100 000, and an acid number between 10 and 250, preferably of 20 to 200, or a hydroxyl number of 50 to 750, preferably of 100 to 500.
14. The mixture according to any of the claims 1 to 13, wherein the amount of the binder or binders is in general 10 to 90% by weight, preferably 20 to 80% by weight, based in each case on the total weight of the non-volatile matter of the mixture.
15. A recording material for the production of printing plates comprising a base and a layer of the photopolymerisable mixture as defined in any of the claims 1 to 14.
16. The recording material according to claim 15, wherein the base is a sheeting, web or plate made of plastic or metal, preferably of aluminium or of an aluminium alloy having an optionally mechanically, chemically and/or electrochemically pretreated surface.
17. The recording material according to claim 15, wherein a top layer which is impermeable or but slightly permeable to oxygen is present on the photosensitive layer.
18. The recording material according to claim 17, wherein the top layer consists of poly(vinyl alcohol), polyvinylpyrrolidone, polyphosphates or a sugar.
19. The recording material according to claim 17, wherein the top layer has a thickness of 0.1 to 10 µm, preferably 1 to 5 µm.
20. A process for the production of a printing plate from the recording material as defined in any of the claims 15 to 19, wherein the recording material is exposed imagewise to IR laser beams having a wavelength between 700 and 1 200 nm and subsequently developed in an organic solvent or solvent mixture or an aqueous alkaline solution.