DE10326324B4 - Lithographic printing plate precursor with coating containing 1,4-dihydropyridine sensitizer, process for imaging and imaged lithographic printing plate - Google Patents

Abstract

wobei
R¹ ausgewählt wird aus einem Wasserstoffatom, -C(O)OR⁷, einem gegebenenfalls substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest und einem gegebenenfalls substituierten Aralkylrest,
R² und R³ unabhängig voneinander ausgewählt werden aus gegebenenfalls substituierten Alkylresten, gegebenenfalls...A negative-working precursor of a lithographic printing plate comprising
(a) an optionally pretreated support and
(b) a radiation-sensitive coating of a composition applied to the support
(i) one or more types of monomers and / or oligomers and / or polymers each having at least one ethylenically unsaturated group which is amenable to free-radical polymerization,
(ii) at least one sensitizer,
(iii) at least one co-initiator capable of forming radicals together with the sensitizer (ii) selected from hexaarylbiimidazoles; and
(iv) optionally one or more components selected from alkali-soluble binders, colorants, exposure indicators, plasticizers, chain transfer agents, leuco dyes, surface active agents, inorganic fillers and thermopolymerization inhibitors,
characterized in that the at least one sensitizer is a 1,4-dihydropyridine derivative of the formula (I)

in which
R ^{1 is} selected from a hydrogen atom, -C (O) OR ⁷ , an optionally substituted alkyl radical, an optionally substituted aryl radical and an optionally substituted aralkyl radical,
R ² and R ^{3 are} independently selected from optionally substituted alkyl radicals, optionally ...

Description

The The invention relates to negative-working lithographic printing plate precursors, in particular those which use 1,4-dihydropyridine derivatives as sensitizers in the radiation-sensitive coating included. The invention concerns Furthermore a method for imaging such precursors and imaged lithographic printing plates.

The The field of lithographic printing is based on immiscibility of oil and water, being the oily one Material or ink preferably from the image area and the Water or dampening agent preferably adopted from the non-image area becomes. If a properly prepared surface is moistened with water and then applied a printing ink, the background or the takes Non-image area the water and rejects the ink while the Image area takes the ink and repels the water. The printing ink on the image area is then applied to the surface of a material, such as paper, Tissue and the like, transferred, on which the picture should be created. In general, the But first transfer ink to an intermediate material called a blanket which then transfers the ink to the surface of the material which the image should be created; This is called offset lithography.

A often used type of lithographic printing plate precursor has one on a carrier aluminum-based, photosensitive coating on. The coating can react to radiation by exposing the exposed one Part so soluble will be removed in the development process. Such a plate is called positive working. Conversely, a plate referred to as negative working when the exposed part of the coating cured by the radiation becomes. In both cases The remaining image area absorbs ink or is oleophilic and the non-image area (background) absorbs water or is hydrophilic. The differentiation between image and non-image areas takes place when exposing, with a film on the plate precursor - to ensure a good contact with vacuum - is applied. The plate is then exposed to a radiation source. Alternatively, you can the plate also digitally without film, e.g. with a UV laser, exposed become. If a positive plate is used, that is the image on the plate corresponding area on the film so opaque that Light does not reach the plate while the non-image area appropriate area on the film is clear and the light transmission on the coating, which is then more soluble is allowed. In the case of a negative plate, the reverse is true to: The area corresponding to the image area on the film is clear while the non-image area is opaque. The coating under the clear film area is hardened by the action of light, while the The area not reached by the light is removed during development. The photohardened surface a negative plate is therefore oleophilic and takes printing ink on, while the non-image area which is affected by the action of a developer removed coating, desensitized and therefore is hydrophilic.

Photosensitive Mixtures have been used for years in photopolymerizable compositions for the preparation of photosensitive materials, e.g. Printing plate precursors used. Specially for however, newer applications (e.g., laser exposure) are becoming an improved sensitivity, especially in the near UV and visible spectral range needed so that the shutter speed is shortened can be. It is also from the economic point of view important that low intensity radiation sources are used can, the cheaper and more reliable are as radiation sources of high intensity. It is therefore for some Time tries to increase the sensitivity of light-sensitive mixtures, which are used in photopolymerizable compositions are supposed to increase.

DE-A-3021599 discloses radiation sensitive compositions which are ethylenic unsaturated monomers and a 2- (halomethyl-phenyl) -4-halo-oxazole derivative as a photoinitiator. However, the efficiency of the photoinitiator is insufficient.

EP-A-0741333 describes photopolymerizable compositions which in addition to ethylenic unsaturated Monomers and organic binders a combination of a optical brightener and a photoinitiator selected from Acyl and diacylphosphine oxides, contain. As optical brighteners are called those which have a Stilbene, triazine, thiazole, benzoxazole, coumarin, xanthene, Triazole, oxazole, thiophene or pyrazoline unit. These However, photopolymerizable compositions show today's No scales sufficient sensitivity.

In US-A-4,181,531 and US-A-4,271,260 are positive working systems described containing 1,4-dihydropyridine derivatives and UV sensitive are.

The Use of 1,4-dihydropyridine in radiation-sensitive systems is also known from US-A-6,143,471. Village become 1,4-dihydropyridines as a solution inhibitor for polymers used in positive-working IR-sensitive compositions.

In US-B-6,291,143 discloses 1,4-dihydropyridines as photoreductants for dyes (such as IR dyes) used in laser thermal transfer systems. The resulting pyridinium salts also function in this system as Crosslinking agent for Hydroxy-functionalized resins.

There negative-working systems, i. cross-linked plates, more resistant across from Pressurized chemicals are considered to be positive-acting systems negative-working systems are preferred, if for particular chemical resistance Value is placed.

negative operating systems containing 1,4-dihydropyridines are described in DD-A-287 796 described. The photopolymerizable compositions disclosed therein contain as co-initiator an onium compound. The with these systems achieved sensitivity is sufficient in no way meet today's requirements.

In DE 42 28 141 C1 . DE 35 40 804 C1 . DE 35 40 796 C1 . DE 30 48 490 A1 . DE 29 45 564 A1 . US 4,292,394 . DE 27 58 209 A1 and DE 42 28 790 C1 Color proofing systems containing, for example, dihydropyridine compounds and hexaarylbiimidazoles are described.

DE 27 58 210 A1 discloses a recording material comprising a binder, a dihydropyridine compound and a hexaarylbisimidazole. DE 27 10 417 A1 describes photopolymerizable compositions containing a nitroaromatic compound.

It It is the object of the invention to have negative-working precursors of Lithographic printing plates with high light sensitivity at the same time good storage stability and provide high print run on the press.

• (a) einen gegebenenfalls vorbehandelten Träger und
• (b) eine auf den Träger aufgebrachte strahlungsempfindliche Beschichtung aus einer Zusammensetzung, umfassend
• (i) ein oder mehrere Arten Monomere und/oder Oligomere und/oder Polymere mit jeweils mindestens einer ethylenisch ungesättigten Gruppe, die einer radikalischen Polymerisation zugänglich ist,
• (ii) mindestens einen Sensibilisator,
• (iii) mindestens einen Co-Initiator, der zusammen mit dem Sensibilisator (ii) Radikale bilden kann und ausgewählt wird aus Hexaarylbiimidazolen; und
• (iv) gegebenenfalls ein oder mehrere Komponenten ausgewählt aus alkalilöslichen Bindemitteln, Farbmitteln, Belichtungsindikatoren, Weichmachern, Kettenübertragungsmitteln, Leucofarbstoffen, oberflächenaktiven Mitteln, anorganischen Füllstoffen und Thermopolymerisationsinhibitoren,

dadurch gekennzeichnet, dass es sich bei dem mindestens einen Sensibilisator um ein 1,4-Dihydropyridin-Derivat der Formel (I) handelt

wobei
R¹ ausgewählt wird aus einem Wasserstoffatom, -C(O)OR⁷, einem gegebenenfalls substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest und einem gegebenenfalls substituierten Aralkylrest,
R² und R³ unabhängig voneinander ausgewählt werden aus gegebenenfalls substituierten Alkylresten, gegebenenfalls substituierten Arylresten, CN und einem Wasserstoffatom,
R⁴ und R⁵ unabhängig voneinander ausgewählt werden aus -C(O)OR⁷, -C(O)R⁷, -C(O)NR⁸R⁹ und CN,
oder R² und R⁴ zusammen einen gegebenenfalls substituierten Phenylring oder einen 5-7-gliedrigen carbocyclischen oder heterocyclischen Ring bilden, wobei in dem carbocyclischen oder heterocyclischen Ring, benachbart zu Position 5 des 1,4-Dihydropyridin-Rings, die Einheit

vorliegt und der carbocyclische oder heterocyclische Ring gegebenenfalls weitere Substituenten aufweist,
oder sowohl R² mit R⁴ als auch R³ mit R⁵ beide entweder gegebenenfalls substituierte Phenylringe oder beide 5-7-gliedrige carbocyclische oder heterocyclische Ringe bilden, wobei in den carbocyclischen oder heterocyclischen Ringen, benachbart zu Position 3 und 5 des Dihydropyridin-Rings, die Einheit

vorliegt und die carbocyclischen oder heterocyclischen Ringe gegebenenfalls weitere Substituenten aufweisen,
oder eines der Paare R²/R⁴ und R³/R⁵ einen 5-7gliedrigen carbocyclischen oder heterocyclischen Ring bildet, wobei in dem carbocyclischen oder heterocyclischen Ring, benachbart zu Position 5 bzw. 3 des Dihydropyridin-Rings, die Einheit

vorliegt und der carbocyclische oder heterocyclische Ring gegebenenfalls weitere Substituenten aufweist, und das andere Paar einen gegebenenfalls substituierten Phenylring bildet,
oder R² mit R¹ oder R³ mit R¹ einen 5- bis 7-gliedrigen heterocyclischen Ring bildet, der gegebenenfalls ein oder mehrere Substituenten aufweisen kann und der gegebenenfalls neben dem Stickstoffatom, das er mit dem 1,4-Dihydropyridinring gemeinsam hat, weitere Stickstoffatome, -NR¹³-Gruppen, -S- oder -O- aufweist,
R¹³ ausgewählt wird aus einem Wasserstoffatom, einem Alkylrest, Arylrest und Aralkylrest,
R⁶ ausgewählt wird aus einem gegebenenfalls mit einem Halogenatom oder einer -C(O)-Gruppe substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest, einem gegebenenfalls substituierten Aralkylrest, einem gegebenenfalls substituierten heterocyclischen Rest und dem Rest

Y ein Alkandiyl oder Arylenrest ist,
R⁷ ein Wasserstoffatom, Arylrest, ein Aralkylrest oder ein Alkylrest ist, wobei der Alkylrest und die Alkyleinheit des Aralkylrests gegebenenfalls ein oder mehrere C-C-Doppel- und/oder C-C-Dreifachbindungen enthalten,
und R⁸ und R⁹ unabhängig voneinander ausgewählt werden aus einem Wasserstoffatom, einem gegebenenfalls substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest und einem gegebenenfalls substituierten Aralkylrest, mit der Maßgabe, daß der Sensibilisator der Formel (I) keine nitroaromatische Verbindung ist.The object of the invention is achieved by a negative-working precursor of a lithographic printing plate comprising

• (a) an optionally pretreated support and
• (b) a radiation-sensitive coating of a composition applied to the support
• (i) one or more types of monomers and / or oligomers and / or polymers each having at least one ethylenically unsaturated group which is amenable to free-radical polymerization,
• (ii) at least one sensitizer,
• (iii) at least one co-initiator capable of forming radicals together with the sensitizer (ii) selected from hexaarylbiimidazoles; and
• (iv) optionally one or more components selected from alkali-soluble binders, colorants, exposure indicators, plasticizers, chain transfer agents, leuco dyes, surface active agents, inorganic fillers and thermopolymerization inhibitors,

characterized in that the at least one sensitizer is a 1,4-dihydropyridine derivative of the formula (I)

in which
R ^{1 is} selected from a hydrogen atom, -C (O) OR ⁷ , an optionally substituted alkyl radical, an optionally substituted aryl radical and an optionally substituted aralkyl radical,
R ² and R ^{3 are} independently selected from optionally substituted alkyl radicals, optionally substituted aryl radicals, CN and a hydrogen atom,
R ⁴ and R ^{5 are} independently selected from -C (O) OR ⁷ , -C (O) R ⁷ , -C (O) NR ⁸ R ⁹ and CN,
or R ² and R ⁴ together form an optionally substituted phenyl ring or a 5-7 membered carbocyclic or heterocyclic ring, wherein in the carbocyclic or heterocyclic ring, adjacent to position 5 of the 1,4-dihydropyridine ring, the moiety

is present and the carbocyclic or heterocyclic ring optionally has further substituents,
both form either optionally substituted phenyl rings or 5-7 membered carbocyclic or heterocyclic rings or both R ² with R ⁴ as well as R ³ with R ^5, wherein, in the carbocyclic or heterocyclic rings adjacent to positions 3 and 5 of the dihydropyridine ring , the unit

is present and the carbocyclic or heterocyclic rings optionally have further substituents,
or one of the pairs R ² / R ⁴ and R ³ / R ⁵ forms a 5-7 membered carbocyclic or heterocyclic ring wherein in the carbocyclic or heterocyclic ring adjacent to positions 5 and 3 of the dihydropyridine ring, respectively

is present and the carbocyclic or heterocyclic ring optionally further substituents, and the other pair forms an optionally substituted phenyl ring,
or R ² with R ¹ or R ³ with R ¹ forms a 5- to 7-membered heterocyclic ring which may optionally have one or more substituents and which optionally has, in addition to the nitrogen atom which it shares with the 1,4-dihydropyridine ring, has further nitrogen atoms, -NR ¹³ groups, -S- or -O-,
R ^{13 is} selected from a hydrogen atom, an alkyl radical, aryl radical and aralkyl radical,
R ^{6 is} selected from an alkyl radical optionally substituted by a halogen atom or a C (O) group, an optionally substituted aryl radical, an optionally substituted aralkyl radical, an optionally substituted heterocyclic radical and the radical

Y is an alkanediyl or arylene radical,
R ^{7 is} a hydrogen atom, aryl radical, an aralkyl radical or an alkyl radical, where the alkyl radical and the alkyl moiety of the aralkyl radical optionally contain one or more CC double and / or C-C triple bonds,
and R ⁸ and R ^{9 are} independently selected from hydrogen, optionally substituted alkyl, optionally substituted aryl and optionally substituted aralkyl, provided that the sensitizer of formula (I) is not nitroaromatic.

Unless defined otherwise, in the context of this invention an alkyl radical is understood to mean a straight-chain, branched or cyclic saturated hydrocarbon radical which preferably has 1 to 18 carbon atoms, more preferably 1 to 10 carbon atoms, and particularly preferably 1 to 6 carbon atoms. The alkyl group may optionally have one or more substituents (preferably 0 or 1 substituent), for example, selected from halogen atoms (fluorine, chlorine, bromine, iodine), CN, NR ¹³ ₂ , C (O) OR ¹³ and OR ¹³ (R ¹³ is independently a hydrogen atom, an alkyl group, aryl group or aralkyl group). The above definition also applies to the alkyl moiety of an aralkyl radical and an alkanediyl radical.

Unless defined otherwise, an aryl radical in the context of this invention is understood as meaning an aromatic carbocyclic radical having one or more fused rings, which preferably has 6 to 14 carbon atoms. The aryl radical may optionally have one or more substituents (preferably 0 to 3), for example selected from halogen atoms, alkyl radicals, alkoxy radicals, CN, NR ¹³ ₂ , SO ₃ H, COOR ¹³ and OR ¹³ (wherein each R ^{13 is} independently hydrogen , Alkyl, aryl and aralkyl is selected). The above definition also applies to the aryl unit of an aralkyl group and an arylene group. Preferred examples are a phenyl group and a naphthyl group, which may be optionally substituted.

in the This invention is under a fused ring or Ring system understood a ring connected to the ring to which it condenses is, has two carbon atoms in common.

Unless otherwise defined, in the context of this invention a heterocyclic radical is understood to mean a 5- to 7-membered (preferably 5- or 6-membered) saturated, unsaturated (non-aromatic) or aromatic ring in which one or more ring carbon atoms is interrupted Heteroatoms selected from N, NR ¹³ , S and O are replaced (preferably N or NR ¹³ ). The heterocyclic ring may optionally have one or more substituents, for example, selected from alkyl radicals, aryl radicals, aralkyl radicals, halogen atoms, -OR ¹³ , -NR ¹³ ₂ , -C (O) OR ¹³ , C (O) NR ¹³ ₂ and CN (wherein each R ^{13 is} independently selected from hydrogen, alkyl, aryl and aralkyl). It goes without saying that due to the given basic structures (I) and (Ia) to (Ig) not every heterocyclic ring can be saturated or unsaturated or aromatic.

In the context of this invention, a carbocyclic ring is understood to mean a 5- to 7-membered (preferably 5- or 6-membered) saturated or unsaturated ring. The carbocyclic ring may optionally have one or more substituents, for example, selected from alkyl radicals, aryl radicals, aralkyl radicals, halogen atoms, CN, -NR ¹³ ₂ , -C (O) OR ¹³ , -C (O) NR ¹³ ₂ and -OR ¹³ ( wherein R ^{13 is} as defined above). It goes without saying that due to the given basic structures (I) and (Ia) to (Ig) not every carbocyclic ring can be unsaturated or saturated.

When ethylenically unsaturated Monomers, oligomers and polymers can all monomers, oligomers and polymers Polymers can be used which are radically polymerizable and having at least one C-C double bond. It can too Monomers / oligomers / polymers with C-C triple bonds are used, but they are not preferred. Suitable compounds are those skilled in the art well known and can without special limitations are used in the present invention. Preferred are esters of acrylic or methacrylic acid, itaconic acid, the Crotonic and isocrotonic acid, the maleic and the fumaric acid with one or more unsaturated Groups in the form of monomers, oligomers or prepolymers. You can in solid or liquid Form are present, with solid and viscous forms are preferred. Examples of compounds which are useful as monomers include Trimethylolpropane triacrylate and methacrylate, pentaerythritol triacrylate and methacrylate, dipentaerythritol monohydroxypentaacrylate and methacrylate, Dipentaerythritol hexaacrylate and methacrylate, pentaerythritol tetraacrylate and methacrylate, di (trimethylolpropane) tetraacrylate and methacrylate, Diethylene glycol diacrylate and methacrylate, triethylene glycol diacrylate and methacrylate or tetraethylene glycol diacrylate and methacrylate. Suitable oligomers or prepolymers are, for example, urethane acrylates and methacrylates, epoxy acrylates and methacrylates, polyester acrylates and methacrylates, polyether acrylates and methacrylates or unsaturated polyester resins.

Next Monomers and / or oligomers can also polymers can be used which radically polymerizable C-C double bonds in the main or side chain included. Examples therefor are reaction products of maleic anhydride-olefin copolymers with hydroxyalkyl (meth) acrylates (see, e.g., DE-A-4311738); (Meth) acrylic acid polymers, partially or completely esterified with allyl alcohol (see, for example, DE-A-3332640); reaction products of polymeric polyalcohols with isocyanato (meth) acrylates; unsaturated polyesters; (meth) acrylate-terminated polystyrenes; Poly (meth) acrylate; acrylic acids, poly (meth) acrylates; Poly (meth) acrylamides; (Meth) acrylic acid polymers, partially or Completely esterified with epoxides, the radically polymerizable groups contain; and polyethers. The prefix "(meth)" indicates in this Connection that uses both derivatives of acrylic acid and methacrylic acid can be.

Further suitable C-C-unsaturated radically polymerizable compounds are e.g. in EP-A-1 176 007 described.

It is of course possible to use various types of monomers or oligomers or polymers in a mixture, as are mixtures of monomers and oligomers and / or polymers used in the invention, and mixtures of oligomers and polymers. The weight fraction of the radical polymerizable monomers / oligomers / polymers is preferably 5 to 95 wt.%, When using monomers / oligomers particularly preferably 20 to 85 wt.%, Based on the dry layer weight of the radiation-sensitive coating. The term "dry layer weight of the radiation-sensitive coating" in the context of this invention is synonymous with "solids of the radiation-sensitive composition".

in the A compound of this invention is a sensitizer understood, which can absorb radiation during exposure, but alone, i. without the addition of coinitiators, can not form radicals.

In The present invention may be a sensitizer or a mixture be used from two or more.

wobei
R¹ ausgewählt wird aus einem Wasserstoffatom, -C(O)OR⁷, einem gegebenenfalls substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest und einem gegebenenfalls substituierten Aralkylrest,
R² und R³ unabhängig voneinander ausgewählt werden aus gegebenenfalls substituierten Alkylresten, gegebenenfalls substituierten Arylresten, CN und einem Wasserstoffatom,
R⁴ und R⁵ unabhängig voneinander ausgewählt werden aus -C(O)OR⁷, -C(O)R⁷, -C(O)NR⁸R⁹ und CN,
oder R² und R⁴ zusammen einen gegebenenfalls substituierten Phenylring oder einen 5-7-gliedrigen carbocyclischen oder heterocyclischen Ring bilden, wobei in dem carbocyclischen oder heterocyclischen Ring, benachbart zu Position 5 des Dihydropyridin-Rings, die Einheit

vorliegt und der carbocyclische oder heterocyclische Ring gegebenenfalls weitere Substituenten aufweist,
oder sowohl R² mit R⁴ als auch R³ mit R⁵ beide entweder gegebenenfalls substituierte Phenylringe oder beide 5-7-gliedrige carbocyclische oder heterocyclische Ringe bilden, wobei in den carbocyclischen oder heterocyclischen Ringen, benachbart zu Position 3 und 5 des Dihydropyridin-Rings, die Einheit

vorliegt und die carbocyclischen oder heterocyclischen Ringe gegebenenfalls weitere Substituenten aufweisen,
oder eines der Paare R²/R⁴ und R³/R⁵ einen 5-7gliedrigen carbocyclischen oder heterocyclischen Ring bildet, wobei in dem carbocyclischen oder heterocyclischen Ring, benachbart zu Position 5 bzw. 3 des Dihydropyridin-Rings, die Einheit

vorliegt und der carbocyclische oder heterocyclische Ring gegebenenfalls weitere Substituenten aufweist, und das andere Paar einen gegebenenfalls substituierten Phenylring bildet,
oder R² mit R¹ oder R³ mit R¹ einen 5- bis 7-gliedrigen heterocyclischen Ring bildet, der gegebenenfalls ein oder mehrere Substituenten aufweisen kann und der gegebenenfalls neben dem Stickstoffatom, das er mit dem 1,4-Dihydropyridinring gemeinsam hat, weitere Stickstoffatome, -NR¹³-Gruppen, -S- oder -O- aufweist,
R¹³ aus einem Wasserstoffatom, einem Alkylrest, Arylrest und einem Aralkylrest ausgewählt wird,
R⁶ ausgewählt wird aus einem gegebenenfalls mit einem Halogenatom oder einer -C(O)-Gruppe substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest, einem gegebenenfalls substituierten Aralkylrest, einem gegebenenfalls substituierten heterocyclischen Rest und dem Rest

Y ein Alkandiyl oder Arylenrest ist,
R⁷ ein Wasserstoffatom, Arylrest, ein Aralkylrest oder ein Alkylrest ist, wobei der Alkylrest und die Alkyleinheit des Aralkylrests gegebenenfalls ein oder mehrere C-C-Doppel- und/oder C-C-Dreifachbindungen enthalten,
und R⁸ und R⁹ unabhängig voneinander ausgewählt werden aus einem Wasserstoffatom, einem gegebenenfalls substituierten Alkylrest, einem gegebenenfalls substituierten Arylrest und einem gegebenenfalls substituierten Aralkylrest, mit der Maßgabe, daß es sich bei der Verbindung der Formel (I) nicht um eine nitroaromatische Verbindung handelt.According to the invention, the sensitizer used is a 1,4-dihydropyridine compound of the formula (I)

in which
R ^{1 is} selected from a hydrogen atom, -C (O) OR ⁷ , an optionally substituted alkyl radical, an optionally substituted aryl radical and an optionally substituted aralkyl radical,
R ² and R ^{3 are} independently selected from optionally substituted alkyl radicals, optionally substituted aryl radicals, CN and a hydrogen atom,
R ⁴ and R ^{5 are} independently selected from -C (O) OR ⁷ , -C (O) R ⁷ , -C (O) NR ⁸ R ⁹ and CN,
or R ² and R ⁴ together form an optionally substituted phenyl ring or a 5-7 membered carbocyclic or heterocyclic ring wherein in the carbocyclic or heterocyclic ring adjacent to position 5 of the dihydropyridine ring, the moiety

is present and the carbocyclic or heterocyclic ring optionally has further substituents,
both form either optionally substituted phenyl rings or 5-7 membered carbocyclic or heterocyclic rings or both R ² with R ⁴ as well as R ³ with R ^5, wherein, in the carbocyclic or heterocyclic rings adjacent to positions 3 and 5 of the dihydropyridine ring , the unit

is present and the carbocyclic or heterocyclic rings optionally have further substituents,
or one of the pairs R ² / R ⁴ and R ³ / R ⁵ forms a 5-7 membered carbocyclic or heterocyclic ring wherein in the carbocyclic or heterocyclic ring adjacent to positions 5 and 3 of the dihydropyridine ring, respectively

is present and the carbocyclic or heterocyclic ring optionally further substituents, and the other pair forms an optionally substituted phenyl ring,
or R ² with R ¹ or R ³ with R ¹ forms a 5- to 7-membered heterocyclic ring which may optionally have one or more substituents, and which may optionally contain, in addition to the nitrogen atom, with it the 1,4-dihydropyridine has in common, further nitrogen atoms, -NR ¹³ groups, -S- or -O-,
R ^{13 is selected} from a hydrogen atom, an alkyl radical, aryl radical and an aralkyl radical,
R ^{6 is} selected from an alkyl radical optionally substituted by a halogen atom or a C (O) group, an optionally substituted aryl radical, an optionally substituted aralkyl radical, an optionally substituted heterocyclic radical and the radical

Y is an alkanediyl or arylene radical,
R ^{7 is} a hydrogen atom, aryl radical, an aralkyl radical or an alkyl radical, where the alkyl radical and the alkyl moiety of the aralkyl radical optionally contain one or more CC double and / or C-C triple bonds,
and R ⁸ and R ^{9 are} independently selected from hydrogen, optionally substituted alkyl, optionally substituted aryl and optionally substituted aralkyl, provided that the compound of formula (I) is not a nitroaromatic compound ,

In a preferred embodiment, R ^{1 is} a hydrogen atom.

When R ² and R ³ do not form rings with adjacent substituents, they are preferably independently selected from C ₁ -C ₅ alkyl radicals or aryl radicals.

When R ⁴ and R ⁵ do not form rings with adjacent substituents, they are preferably independently selected from -C (O) OR ⁷ .

R ⁶ is preferably selected from C ₁ -C ₅ -alkyl radicals or aryl radicals.

R ⁷ is preferably selected from C ₁ -C ₅ alkyl radicals and is more preferably a methyl group.

According to one embodiment, the substitution of the 1,4-dihydropyridine ring with R ² / R ⁴ and R ³ / R ^{5 is} symmetrical, ie R ² = R ³ and R ⁴ = R ⁵ .

In a preferred embodiment, R ² and R ^{3 are} independently selected from optionally substituted alkyl radicals, optionally substituted aryl radicals, CN and a hydrogen atom, and R ⁴ and R ⁵ are independently selected from -C (O) OR ⁷ , -C (O) R ⁷ , -C (O) NR ⁸ R ⁹ and CN selected.

wobei R¹ und R⁶ wie vorstehend definiert sind,
die Reste R^8a bis R^8d und R^9a bis R^9d unabhängig aus einem Wasserstoffatom, Alkylresten und Arylresten ausgewählt werden, wobei 2 Reste R⁹ bzw. R⁸ von benachbarten Ringkohlenstoffatomen auch miteinander einen gesättigten oder ungesättigten carbocyclischen oder heterocyclischen Ring oder ankondensierten aromatischen Ring bilden können,
jedes Z unabhängig aus CR¹³ ₂, O, S und NR¹³ ausgewählt wird und
jedes R¹³ unabhängig ein Wasserstoffatom, ein Alkyl-, Aralkyl- oder Arylrest ist,
der Formel (Ib)

wobei R¹ und R⁶ wie vorstehend definiert sind, und
R^10a bis R^10d und R^11a bis R^11d unabhängig aus einem Wasserstoffatom, Alkylresten, Arylresten, Aralkylresten, Halogenatomen (Fluor, Chlor, Brom, Iod), CN, NR¹³ ₂, C(O)OR¹³ und OR¹³, (jedes R¹³ bedeutet unabhängig ein Wasserstoffatom, einen Alkylrest, Arylrest oder Aralkylrest) ausgewählt wird, wobei zwei Reste R¹¹ bzw. R¹⁰ von benachbarten Ringkohlenstoffatomen auch miteinander einen ungesättigten carbocyclischen oder heterocyclischen Ring oder ankondensierten aromatischen Ring bilden können,
der Formel (Ic)

wobei R¹, R³, R⁵ und R⁶ wie vorstehend definiert sind und die Reste R^9a bis R^9f unabhängig aus einem Wasserstoffatom, Alkylresten, Arylresten, Aralkylresten, Halogenatomen (Fluor, Chlor, Brom, Iod), CN, NR¹³ ₂, C(O)OR¹³ und OR¹³, (R¹³ bedeutet unabhängig ein Wasserstoffatom, einen Alkylrest, Arylrest oder Aralkylrest) ausgewählt wird, wobei 2 Reste R⁹ von benachbarten Ringkohlenstoffatomen auch miteinander einen gesättigten oder ungesättigten carbocyclischen oder heterocyclischen Ring oder ankondensierten aromatischen Ring bilden können,
der Formel (Id)

wobei jedes R¹, R², R³, R⁴ und R⁵ unabhängig wie vorstehend definiert ist und Y ausgewählt wird aus Alkandiyl und Arylen,
der Formel (Ie)

wobei R², R⁴, R⁵ und R⁶ wie vorstehend definiert sind und die Reste R^9a bis R^9f wie vorstehend die Reste R^9a bis R^9d von Formel (Ia) definiert sind,
der Formel (If)

wobei R², R⁴, R⁵ und R⁶ wie vorstehend definiert sind und die Reste R^9a bis R^9h wie vorstehend die Reste R^9a bis R^9d von Formel (Ia) definiert sind
und der Formel (Ig)

wobei R², R⁴, R⁵ und R⁶ wie vorstehend definiert sind und die Reste R^11a bis R^11d unabhängig aus Wasserstoff, Alkylresten, Arylresten, Aralkylresten, Halogenatomen (Fluor, Chlor, Brom, Iod), CN, NR¹³ ₂, COOR¹³ und OR¹³ (R¹³ bedeutet unabhängig ein Wasserstoffatom, einen Alkylrest, einen Arylrest und einen Aralkylrest) ausgewählt werden, wobei 2 benachbarte Reste R¹¹ von benachbarten Ringkohlenstoffatomen zusammen auch einen ungesättigten carbocyclischen oder heterocyclischen Ring oder ankondensierten aromatischen Ring bilden können.Also suitable as sensitizers are 1,4-dihydropyridine derivatives of the formula (Ia)

wherein R ¹ and R ^{6 are} as defined above,
the radicals R ^8a to R ^8d and R ^9a to R ^{9d are} independently selected from a hydrogen atom, alkyl radicals and aryl radicals, wherein 2 radicals R ⁹ and R ⁸ of adjacent ring carbon atoms also together contain a saturated or unsaturated carbocyclic or heterocyclic ring or fused aromatic ring can form
each Z is independently selected from CR ¹³ ₂ , O, S and NR ¹³ , and
each R ^{13 is} independently a hydrogen atom, an alkyl, aralkyl or aryl radical,
of the formula (Ib)

wherein R ¹ and R ^{6 are} as defined above, and
R ^10a to R ^10d and R ^11a to R ^11d independently of a hydrogen atom, alkyl radicals, aryl radicals, aralkyl radicals, halogen atoms (fluorine, chlorine, bromine, iodine), CN, NR ¹³ ₂ , C (O) OR ¹³ and OR ¹³ , ( each R ¹³ is independently a hydrogen atom, an alkyl radical, aryl radical or aralkyl radical) is selected, wherein two radicals R ¹¹ and R ¹⁰ of adjacent ring carbon atoms also with each other can form an unsaturated carbocyclic or heterocyclic ring or fused aromatic ring,
of the formula (Ic)

wherein R ¹ , R ³ , R ⁵ and R ^{6 are} as defined above and the radicals R ^9a to R ^{9f are} independently selected from hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, halogen atoms (fluorine, chlorine, bromine, iodine), CN, NR ¹³ ₂ , C (O) OR ¹³ and OR ¹³ , (R ¹³ is independently a hydrogen atom, an alkyl group, aryl group or aralkyl group) wherein 2 R ⁹ of adjacent ring carbon atoms also together or a fused or unsaturated carbocyclic or heterocyclic ring or fused can form aromatic ring,
the formula (Id)

wherein each of R ¹ , R ² , R ³ , R ⁴ and R ^{5 is} independently defined as above and Y is selected from alkanediyl and arylene,
of the formula (Ie)

where R ² , R ⁴ , R ⁵ and R ^{6 are} as defined above and the radicals R ^9a to R ^{9f are} as defined above the radicals R ^9a to R ^9d of formula (Ia),
the formula (If)

wherein R ² , R ⁴ , R ⁵ and R ^{6 are} as defined above and the radicals R ^9a to R ^9h as above the radicals R ^9a to R ^9d of formula (Ia) are defined
and the formula (Ig)

wherein R ² , R ⁴ , R ⁵ and R ^{6 are} as defined above and the radicals R ^11a to R ^{11d are} independently selected from hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, halogen atoms (fluorine, chlorine, bromine, iodine), CN, NR ¹³ ₂ , COOR ¹³ and OR ¹³ (R ¹³ is independently a hydrogen atom, an alkyl group, an aryl group and an aralkyl group), where 2 adjacent groups R ¹¹ of adjacent ring carbon atoms together can also form an unsaturated carbocyclic or heterocyclic ring or fused aromatic ring.

It goes without saying that the number of radicals R ⁸ or R ⁹ in the formulas (Ia), (Ic), (Ie) and (If) decreases if 2 radicals R ⁸ or R ⁹ of adjacent ring carbon atoms together form a fused aromatic ring.

In the 1,4-dihydropyridine derivatives of the formula (Ia), R ^{1 is} preferably a hydrogen atom, R ^{6 is} a methyl or phenyl group and Z is preferably O or CH ₂ ; the substituents R ^8a to R ^8d and R ^9a to R ^9d are independently preferably selected from hydrogen atoms and methyl groups. Of the derivatives of the formula (Ia), those with symmetrical substitution on the dihydropyridine ring are particularly preferred.

In the derivatives of the formula (Ib), R ^{1 is} preferably a hydrogen atom and R ^{6 is} preferably a methyl or phenyl group. The substituents R ^10a to R ^10d and R ^11a to R ^11d are independently preferably selected from C ₁ -C ₅ alkyl groups, OR ¹³ and halogen atoms; a symmetrical substitution of the two benzene rings is particularly preferred.

In the 1,4-dihydropyridine derivatives of the formula (Ic), R ^{1 is} preferably a hydrogen atom, R ^{6 is} preferably a methyl or phenyl group, R ^{3 is} preferably a methyl group and R ^{5 is} preferably C (O) OR ⁷ (where R ^{7 is} as shown in FIG is defined above). The substituents R ^9a to R ^9f are independently preferably selected from C ₁ -C ₅ alkyl groups. Particularly preferred is a methyl group.

In the derivatives of the formula (Id), Y is preferably a 1,4-phenylene or 1,2-ethylene group. In addition, it is preferred that both R ^{1 are the} same, both R ^{2 are the} same, both R ^{3 are the} same, both R ^{4 are the} same and both R ^{5 are the} same; for all radicals R ¹ to R ⁵ , the preferred definitions given for formula (I) apply.

In the derivatives of the formula (Ie), R ^{2 is} preferably C ₁ -C ₅ alkyl, R ^{4 is} preferably -C (O) OR ⁷ , R ^{5 is} preferably C (O) OR ⁷ and R ^{6 is} preferably C ₁ -C ₅ alkyl or phenyl radicals (R ⁷ is as defined above). The substituents R ^9a to R ^9f are preferably independently selected from C ₁ -C ₅ alkyl radicals.

In the derivatives of the formula (If) R ^{2 is} preferably C ₁ -C ₅ alkyl, R ^{4 is} preferably C (O) OR ⁷ , R ^{5 is} preferably C (O) OR ⁷ and R ^{6 is} preferably a C ₁ -C ₅ alkyl or a phenyl radical (wherein R ⁷ is as defined above). The substituents R ^9a to R ^9h are preferably independently selected from C ₁ -C ₅ alkyl radicals.

In the derivatives of formula (Ig), R ^{2 is} preferably C ₁ -C ₅ alkyl, R ^{4 is} preferably C (O) OR ⁷ , R ^{5 is} preferably C (O) OR ⁷ and R ^{6 is} preferably C ₁ -C ₅ alkyl - or a phenyl radical. The substituents R ¹¹ are preferably independently selected from C ₁ -C ₅ alkyl groups.

From the 1,4-dihydropyridine derivatives of the formulas (Ia) to (Ig) those of formulas (Ia) and (Id) are particularly preferred.

The used according to the invention 1,4-dihydropyridine derivatives can methods well known to those skilled in the art, such as the Hantzsch synthesis, getting produced. For example, see J. Org. Chem. 30 (1965), p.1914 et seq., And Angewandte Chemie (Intern.), 20 (1981), Pp. 762 ff., Referenced; the procedures outlined in it can be by appropriate variation of the starting materials used also for the Synthesis use there not explicitly described 1,4-dihydropyridines.

The Amount of sensitiser (s) is not particularly limited but preferably in the range of 0.2 to 25% by weight, based on the Dry layer weight of the coating, more preferably at 0.5 to 15% by weight.

in the A compound of this invention is a coinitiator understood that together with the sensitizers used in the invention Radical forms. According to the invention the coinitiators selected from 2,2 ', 4,4', 5,5'-hexaarylbiimidazoles (hereinafter abbreviated Hexaarylbiimidazoles).

wobei A¹-A⁶ substituierte oder unsubstituierte C₅-C₂₀ Arylreste sind, die gleich oder verschieden sind und bei denen im Ring ein oder mehrere C-Atome gegebenenfalls durch Heteroatome, ausgewählt aus O, N und S, ersetzt sein können. Als Substituenten der Arylreste sind solche möglich, die die lichtinduzierte Dissoziation zu Triarylimidazolyl-Radikalen nicht behindern, z.B. Halogenatome (Fluor, Chlor, Brom, Jod), -CN, C₁-C₆ Alkylreste (gegebenenfalls mit ein oder mehreren Substituenten, ausgewählt aus Halogenatomen, -CN und -OH), C₁-C₆ Alkoxy, C₁-C₆ Alkylthio, (C₁-C₆ Alkyl) sulfonyl.Suitable hexaarylbiimidazoles can be represented, for example, by the following formula (II):

where A ¹ -A ^{6 are} substituted or unsubstituted C ₅ -C ₂₀ aryl radicals which are identical or different and in which one or more C atoms in the ring may optionally be replaced by heteroatoms selected from O, N and S. As substituents of the aryl radicals, those are possible which do not hinder the light-induced dissociation to triarylimidazolyl radicals, eg halogen atoms (fluorine, chlorine, bromine, iodine), -CN, C ₁ -C ₆ alkyl radicals (optionally with one or more substituents selected from Halogen atoms, -CN and -OH), C ₁ -C ₆ alkoxy, C ₁ -C ₆ alkylthio, (C ₁ -C ₆ alkyl) sulfonyl.

preferred Aryl radicals are substituted and unsubstituted phenyl, biphenyl, Naphthyl, pyridyl, furyl and thienyl radicals. Especially preferred are substituted and unsubstituted phenyl radicals; especially preferred are halogen-substituted phenyl radicals.

Examples are:
2,2'-Bis (bromophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (p-carboxyphenyl) -4,4 ', 5,5''- tetraphenylbiimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis (p-methoxyphenyl) biimidazole,
2,2'-bis (p-chlorophenyl) -4,4 ', 5,5'-tetrakis (p-methoxyphenyl) biimidazole,
2,2'-bis (p-cyanophenyl) -4,4'5,5'-tetrakis (p-methoxyphenyl) biimidazole,
2,2'-bis (2,4-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (2,4-dimethoxyphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (o-ethoxyphenyl) ', 5,5'-tetraphenylbiimidazole, -4.4
2,2'-bis (m-fluorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (o-fluorophenyl) ', 5,5'-tetraphenylbiimidazole, -4.4
2,2'-bis (p-fluorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (o-hexoxyphenyl) ', 5,5'-tetraphenylbiimidazole, -4.4
2,2'-bis (o-hexylphenyl) -4,4 ', 5,5'-tetrakis (p-methoxyphenyl) biimidazole,
2,2'-bis (3,4-methylenedioxyphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetrakis [m- (betaphenoxy-ethoxyphenyl)] biimidazole,
2,2'-bis (2,6-dichloro-phenyl) ', 5,5'-tetraphenyl, -4.4
2,2'-bis (o-methoxyphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (p-methoxyphenyl) -4,4'-bis (o-methoxyphenyl) -5,5'-diphenylbiimidazol,
2,2'-bis (o-nitrophenyl) ', 5,5'-tetraphenylbiimidazole, -4.4
2,2'-bis (p-phenylsulfonylphenyl) -4,4 ', 5,5'-tetraphenyl-biimidazole,
2,2'-bis (p-sulfamoylphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (2,4,5-trimethylphenyl) ', 5,5'-tetraphenylbiimidazole, -4.4
2,2'-di-4-biphenylyl-4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-di-1-naphthyl-4,4 ', 5,5'-tetrakis (p-methoxyphenyl) biimidazole,
2,2'-di-9-phenanthryl-4,4 ', 5,5'-tetrakis (p-methoxyphenyl) biimidazole,
2,2'-diphenyl-4,4 ', 5,5'-tetra-4-biphenylylbiimidazol,
2,2'-diphenyl-4,4 ', 5,5'-tetra-2,4-xylylbiimidazol,
2,2'-di-3-pyridyl-4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-di-3-thienyl-4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-di-o-tolyl-4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-di-p-tolyl-4,4'-di-o-tolyl-5,5'-diphenylbiimidazol,
2,2'-di-2,4-xylyl-4,4 ', 5,5'-tetraphenylbiimidazole,
2,2 ', 4,4', 5,5'-hexakis (p-benylthiophenyl) biimidazole,
2,2 ', 4,4', 5,5'-hexa-1-naphthylbiimidazol,
2,2 ', 4,4', 5,5'-Hexaphenylbiimidazol,
2,2'-bis (2-nitro-5-methoxyphenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (o-nitrophenyl) -4,4 ', 5,5'-tetrakis (m-methoxyphenyl) biimidazole,
2,2'-bis (2-chloro-5-sulfophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2 ', 5-tris (2-chlorophenyl) -4- (3,4-dimethoxyphenyl) -4,5'diphenylbiimidazol,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (p-fluorophenyl) biimidazole,
2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetra (p-iodophenyl) biimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (p-chloronaphthyl) biimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (p-chlorophenyl) biimidazole,
2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetra (p-chloro-p-methoxyphenyl) biimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (o, p-dichlorophenyl) biimidazole,
2,2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetra (o, p-dibromophenyl) biimidazole,
2,2'-bis (o-bromophenyl) -4,4 ', 5,5'-tetra (o, p-dichlorophenyl) biimidazole or
2,2'-bis -4,4 ', 5,5', (o, p-dichlorophenyl) - tetra (o, p-dichlorophenyl) biimidazole;
but the invention is not limited thereto.

suitable Hexaarylbiimidazoles are z. In US-A-4,565,769 and US-A-3,445,232 described and can prepared by known methods, e.g. the oxidative Dimerization of triarylimidazoles.

In of the present invention may be a hexaarylbiimidazole or a Mixture of several be used as a coinitiator.

The Amount of the coinitiator (s) is not particularly limited but preferably at 0.2 to 25% by weight, based on the dry layer weight, particularly preferably at 0.5 to 15 wt.%.

Possibly For example, the radiation-sensitive coating may also be an alkali-soluble one Contain binder or binder mixture. The binder will preferably selected from polyvinyl acetals, acrylic polymers, polyurethanes and their copolymers. It is preferred that the binder contains acid groups, especially preferably carboxyl groups. Most preferred are acrylic polymers. Binders with acid groups preferably have an acid number in the range of 20 to 180 mg KOH / g polymer. If necessary, can the binder contain groupings that are capable of one Cycloaddition (e.g., photocycloaddition). The amount The binder is not particularly limited and is preferably in the range of 0 to 90 wt.%, Particularly preferably 5 to 60 wt.%.

The radiation-sensitive coating may also contain small amounts of Thermopolymerization inhibitors included. Suitable examples of inhibitors the unwanted Thermopolymerization are e.g. Hydroquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrrogalol, t-butylcatechol, benzoquinone, 4,4'-thio-bis (3-methyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol) and N-nitrosophenylhydroxylamine salts. The amount of non-absorbable Polymerization inhibitors in the radiation-sensitive coating is preferably 0% by weight to 5% by weight, based on the dry layer weight, particularly preferably 0.01 to 2 wt.%. In many cases, such inhibitors reach commercial Monomers or oligomers in the radiation-sensitive coating and therefore are not explicit expelled.

In addition, the radiation-sensitive coating may contain dyes or pigments for coloring the layer. It goes without saying that the colorant must be selected so that the he xaarylbiimidazole does not decompose sensitized; suitable colorants can be determined by the skilled person by simple experiments or by calculations based on redox data. Examples of the colorant are, for example, phthalocyanine pigments, azo pigments, carbon black, titanium dioxide, azo dyes, triarylmethane dyes, anthraquinone dyes and cyanine dyes. The use of pigments is preferable because the phase separation can suppress the sensitization of hexaarylbiimidazole. The amount of the colorant is preferably 0 to 20% by weight, based on the dry layer weight, particularly preferably 0.5 to 10% by weight.

to Improvement of the physical properties of the cured layer For example, the radiation-sensitive coating may also contain other additives such as Contain softener. Suitable plasticizers include e.g. dibutyl phthalate, Dioctyl phthalate, didodecyl phthalate, dioctyl adipate, dibutyl sebacate, Triacetylglycerol and tricresylphosphate. The amount of plasticizer is not particularly limited is but preferably 0 to 10% by weight, based on the dry layer weight, particularly preferably 0.25 to 5 wt.%.

The radiation sensitive coating may also include known chain transfer agents such as B. mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole and 3-mercaptotriazole. They are preferably in one Amount from 0 to 15% by weight, based on the dry layer weight, used, more preferably 0.5 to 5 wt.%.

In addition, can contain the radiation-sensitive coating leuco dyes, such as. Leuco Crystal Violet and Leucomalachite Green. Your Amount is preferably 0 to 10% by weight, based on the dry layer weight, particularly preferably 0.5 to 5 wt.%.

Of Furthermore, the radiation-sensitive coating can be surface-active Contain funds. Suitable examples are siloxane-containing polymers, fluorine-containing polymers and polymers having ethylene oxide and / or propylene oxide groups. Your amount is preferably 0 to 10% by weight, based on the dry layer weight, particularly preferably 0.2 to 5 wt.%.

Further optional constituents of the radiation-sensitive coating are, for example, inorganic fillers, such as, for example, Al ₂ O ₃ and SiO ₂ . They are preferably present in an amount of 0 to 20 wt.%, Based on the dry layer weight, before, particularly preferably 0.1 to 5 wt.%.

Exposure indicators, such as. 4-phenylazodiphenylamine, may also be optional Components of the radiation-sensitive coating available be; their amount is preferably 0 to 5 wt.%, Particularly preferably 0 to 2 wt.%, Based on the dry layer weight.

at the preparation of printing form precursors is preferred as the carrier a dimensionally stable plate or foil-shaped Material used. As such a dimensionally stable plate or film material is preferably used that already previously as a carrier for printed matter has been used. Examples of such a carrier include paper, Paper made with plastics (such as polyethylene, polypropylene or Polystyrene), a metal plate or foil, such as e.g. Aluminum (including Aluminum alloys), zinc and copper plates, plastic films from, for example, cellulose diacetate, cellulose triacetate, cellulose propionate, Cellulose acetate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, Polystyrene, polypropylene, polycarbonate and polyvinyl acetate, and a laminate of paper or a plastic film and one of the above Metals or a paper / plastic film that metallizes by vapor deposition has been.

Under these carriers For example, an aluminum plate or foil is particularly preferred since it remarkably dimensionally stable and is cheap and besides shows excellent adhesion of the coating. In addition, can a composite foil used in which an aluminum foil is laminated to a polyethylene terephthalate film.

One Metal support, in particular an aluminum support, is preferably selected from at least one treatment Roughening (e.g., by brushing in the dry state, or brushes with abrasive suspensions or by electrochemical means, e.g. with a hydrochloric acid electrolyte), Anodization (e.g., in sulfuric acid or phosphoric acid) and subjected to hydrophilization.

To improve the hydrophilic properties of the surface of the roughened and optionally anodized in sulfuric or phosphoric acid oxidized metal support this can be a post-treatment with an aqueous solution of sodium silicate, calcium zirconium fluoride, polyvinylphosphonic acid or phosphorus be subjected to acid. In the context of this invention, the term "carrier" also includes an optionally pretreated carrier which has, for example, a hydrophilizing layer on the surface.

The Details of the o.g. Substrate pretreatment are well known to those skilled in the art.

The radiation-sensitive composition is used to prepare a radiation-sensitive precursor according to the present Invention with conventional Coating process (e.g., spin coating, dip coating, Coating by doctor) applied to the surface of the carrier. It is also possible that apply radiation-sensitive composition on both sides of the support; however, it is preferred that in the precursors of the invention only on one side of the carrier a radiation-sensitive coating is applied.

The radiation-sensitive composition contains one or more organic Solvent.

When solvent are lower alcohols (e.g., methanol, ethanol, propanol and butanol), Glycol ether derivatives (e.g., ethylene glycol monomethyl ether, ethylene glycol dimethyl ether, Propylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, Ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, Propylene glycol monoethyl ether acetate, ethylene glycol monoisopropyl ether acetate, Ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether, Diethylene glycol monoethyl ether), ketones (e.g., diacetone alcohol, acetylacetone, Acetone, methyl ethyl ketone, cyclohexanone, methyl isobutyl ketone), Esters (e.g., methyl lactate, ethyl lactate, ethyl acetate, 3-methoxypropyl acetate and butyl acetate), Aromatics (e.g., toluene and xylene), cyclohexane, methoxymethoxyethanol, γ-butyrolactone and dipolar aprotic solvents (e.g., THF, dimethylsulfoxide, dimethylformamide and N-methylpyrrolidone) suitable. The solids content of the applied radiation-sensitive Mix is hanging from the coating method used and is preferably 1 to 50% by weight.

The additional application of a water-soluble oxygen barrier layer on the radiation-sensitive layer may be advantageous. Suitable polymers for the topcoat include polyvinyl alcohol, polyvinyl alcohol / polyvinyl acetate copolymers, polyvinyl pyrrolidone, polyvinyl pyrrolidone / polyvinyl acetate copolymers, polyvinyl methyl ethers, ring-opened copolymers of maleic anhydride and a comonomer such as methyl vinyl ether, polyacrylic acid, cellulose ether, gelatin, etc .; preferred is polyvinyl alcohol. Preferably, the oxygen barrier topcoat composition is applied in the form of a solution in water or a water miscible solvent; In any case, the solvent is selected so that the already existing radiation-sensitive coating does not dissolve. The coating weight of the covering layer may be, for example, 0.1 to 6 g / m ² , and particularly preferably 0.5 to 4 g / m ² . However, the printing plate precursors according to the invention have excellent properties even without a cover layer. The topcoat may also contain matting agents (ie, organic or inorganic particles of 2 to 20 microns in particle size) which, when exposed to contact, facilitate the flatness of the film. In order to improve the adhesion of the cover layer to the radiation-sensitive layer, the cover layer may contain adhesion promoters such as poly (vinylpyrrolidone), poly (ethyleneimine) and poly (vinylimidazole).

suitable Cover layers are e.g. in WO 99/06890.

The thus prepared radiation-sensitive printing plate precursor in the manner known to those skilled in the art with UV radiation (preferably 250-450 nm) imagewise exposed and then with a commercial aqueous developed alkaline developer. As a radiation source z. B. Metallhalogeniddotierte mercury lamps and UV-emitting light Diodes (UV LED) can be used. Of particular interest are as a radiation source UV laser diodes, the UV radiation in the field around 405 nm (e.g., 405 ± 10 nm). After the picturewise Exposure, i. Before developing, a heat treatment at 50 to 180 ° C, preferably 90-150 ° C, be made. The developed elements can be treated in the usual way with a preservative ("Gumming"). The preservatives are aqueous solutions of hydrophilic polymers, wetting agents and other additives.

It is furthermore favorable to increase the mechanical strength of the coating parts remaining after the development by a heat treatment (so-called "burn-in") and / or combination of burn-in and flood exposure (eg with UV light) treated with a solution which protects the non-image areas such that the heat treatment does not cause color acceptance of these areas, a suitable solution being described for example in US-A-4 355 096. The baking is carried out at a temperature in the range 150-250 ° C. Printing plates, the have been prepared from radiation-sensitive precursors according to the invention, but show excellent properties even without heat treatment. If both burned and flood-exposed, the two treatment steps can be carried out simultaneously or in succession.

The radiation-sensitive printing plate precursor according to the present invention are characterized by excellent stability in yellow light conditions, high photosensitivity and excellent resolving power at the same time good storage stability out. The developed printing plates show excellent abrasion resistance, which makes high circulation possible are.

The The invention will be explained in more detail with reference to the following examples.

Examples

Preparation Examples 1-3

0.2 mol of methyl acetoacetate (available from Aldrich), 0.1 mol of the aldehyde corresponding to the 4-substituent, and 0.11 mol of ammonium acetate were dissolved in 30 ml of methanol. This Mixture was heated to boiling for 3 hours. The formed after cooling Precipitate was filtered off and placed in a vacuum oven one day at 40 ° C dried. The products were then dissolved in solvents or solvent mixtures such as recrystallized in Table 1. The 1,4-dihydropyridine structure was determined by UV spectra (Absorption wavelength A and extinction coefficient ε see Table 1) recorded in methanol.

Table 1

Production Example 4

3,3 ', 6,6'-tetramethyl-9-phenyl-1,2,3,4,5,6,7,8,9,10-decahydroacridin-1,8-dione

5.3 g of benzaldehyde, 14 g of 5,5-dimethyl-1,3-cyclohexanedione (available from Aldrich) and 4.5 g of ammonia Umacetat were dissolved in 35 ml of methanol. This mixture was heated to boiling for 5 hours. The precipitate formed after cooling was filtered off, recrystallized from methanol and dried in a vacuum oven at 40 ° C for one day. Yield: 13.4 g (77%); Melting point: 275-277 ° C; λ = 375 nm; ε = 25.4 l / g × cm.

Examples 1 to 4 and Comparative Examples 1 to 6

Exposure with a Ga-doped MH Lamp

A electrochemically (in HCl) roughened and anodized aluminum foil was treated with an aqueous solution of polyvinylphosphonic acid (PVPA) and dried after drying as described in Table 2 solution coated and dried.

Table 2

The solution was filtered, applied to the lithographic support and the coating dried at 90 ° C for 4 minutes. The dry layer weight of the photopolymer layer was about 1.6 g / m ² .

The resulting samples were topcoated by coating with an aqueous solution of poly (vinyl alcohol) (Airvol 203 from Airproducts, with a degree of hydrolysis of 88%); the topcoat after drying at 90 ° C for 4 minutes had a dry film weight of about 2 g / m ² .

The printing plate precursor was coated with a Ga doped MH lamp having an energy of 1.7 mJ / cm ² in a vacuum frame, using a gray wedge with a density in the range of 0.15 to 1.95, whose density increments were 0.15 (UGRA wedge). Immediately after exposure, the plate was heated in an oven at 90 ° C for 2 minutes.

Subsequently, the exposed plate was treated for 30 seconds with a developing solution containing the following components:
3.4 parts by weight Rewopol NLS 28 ^® (available from REWO)
1.1 parts by weight of diethanolamine
1.0 parts by weight Texapon 842 ^® (available from Henkel)
0.6 parts by weight Nekal BX Paste ^® (available from BASF)
0.2 parts by weight of 4-toluenesulfonic acid and
93.7 parts by weight of water

Subsequently was the developer solution rubbed for another 30 seconds with a tampon on the surface and then rinse the entire plate with water. After this treatment the exposed parts remained on the plate. For evaluation the photosensitivity was the plate in the wet state with a Ink blackened.

to Assessment of storage stability The plates became the unexposed printing plate precursors for 60 minutes at 90 ° C stored in an oven, then exposed and as described above developed (storage life test).

to Preparation of a lithographic printing plate was an imaging Layer applied to an aluminum foil as described above, exposed, heated, developed and developed after rinsing with water Abraded plate and with an aqueous solution of 0.5% phosphoric acid and Rubberized 6% gum arabic. The plate thus produced was in a sheetfed offset press clamped and an abrasive ink (Offset S 7184 available from Sun Chemical containing 10% potassium carbonate).

The Results are summarized in Table 3.

Example 5 and Comparative Example 7

Exposure with a 405 nm laser diode

For Example 5, the same coating composition was used as in Example 4. For Comparative Example 7, the same coating composition was used as in Comparative Example 1. Both plates were coated using the UGRA gray wedge with a 405 nm emitting laser diode with an energy of 300 μJ / cm ² exposed. The plates were then developed as described in Examples 1 to 4 and Comparative Examples 1 to 6.

The following results were obtained:
Example 5: gray wedge 3/7; Gray wedge 3/7 for the plate after storage at 90 ° C for 60 minutes
Comparative Example 7: No image was obtained

The inventive examples demonstrate the synergistic effect of the combination of 1,4-dihydropyridines with hexaarylbiimidazoles in the initiation of radical polymerization; The radiation-sensitive coatings are characterized by a very high sensitivity.

Claims (11)

A negative-working precursor of a lithographic printing plate comprising (a) an optionally pretreated support and (b) a radiation-sensitive coating of a composition applied to the support comprising (i) one or more types of monomers and / or oligomers and / or polymers each having at least one (ii) at least one sensitizer, (iii) at least one co-initiator capable of forming radicals together with the sensitizer (ii) selected from hexaarylbiimidazoles; and (iv) optionally one or more components selected from alkali-soluble binders, colorants, exposure indicators, plasticizers, chain transfer agents, leuco dyes, surfactants, inorganic fillers and thermopolymerization inhibitors, characterized in that the at least one sensitizer is a 1,4-dihydropyridine Derivative of formula (I)

wherein R ^{1 is} selected from hydrogen, -C (O) OR ⁷ , optionally substituted alkyl, optionally substituted aryl, and optionally substituted aralkyl, R ² and R ^{3 are} independently selected from optionally substituted alkyl, optionally substituted aryl, CN and a hydrogen atom, R ⁴ and R ^{5 are} independently selected from -C (O) OR ⁷ , -C (O) R ⁷ , -C (O) NR ⁸ R ⁹ and CN, or R ² and R ⁴ together form an optionally substituted phenyl ring or a 5-7 membered carbocyclic or heterocyclic ring, wherein in the carbocyclic or heterocyclic ring, adjacent to position 5 of the 1,4-dihydropyridine ring, the moiety

is present and the carbocyclic or heterocyclic ring optionally further substituents, or both R ² with R ⁴ and R ³ with R ^{5 are} both either optionally substituted phenyl rings or both Form 5-7 membered carbocyclic or heterocyclic rings, wherein in the carbocyclic or heterocyclic rings adjacent to positions 3 and 5 of the dihydropyridine ring, the moiety

is present and the carbocyclic or heterocyclic rings optionally have further substituents, or one of the pairs R ² / R ⁴ and R ³ / R ⁵ forms a 5-7 membered carbocyclic or heterocyclic ring, wherein in the carbocyclic or heterocyclic ring, adjacent to position 5 or 3 of the dihydropyridine ring, the unit

is present and the carbocyclic or heterocyclic ring optionally further substituents, and the other pair forms an optionally substituted phenyl ring, or R ² with R ¹ or R ³ with R ¹ forms a 5- to 7-membered heterocyclic ring, optionally one or more Substituents may have and which optionally in addition to the nitrogen atom, which it shares with the 1,4-dihydropyridine has further nitrogen atoms, -NR ¹³ groups, -S- or -O-, R ^{13 is} selected from a hydrogen atom, an alkyl radical , Aryl group and aralkyl group, R ^{6 is} selected from an alkyl group optionally substituted with a halogen atom or a C (O) group, an optionally substituted aryl group, an optionally substituted aralkyl group, an optionally substituted heterocyclic group and the rest

Y is an alkanediyl or arylene radical, R ^{7 is} a hydrogen atom, aryl radical, an aralkyl radical or an alkyl radical, wherein the alkyl radical and the alkyl moiety of the aralkyl radical optionally contain one or more CC double and / or C-C triple bonds, and R ⁸ and R ^{9 are} independently selected from hydrogen, optionally substituted alkyl, optionally substituted aryl and optionally substituted aralkyl, provided that the sensitizer of formula (I) is not a nitroaromatic compound. A precursor according to claim 1, wherein the sensitiser used is a 1,4-dihydropyridine derivative of the formula (I) in which R ² and R ^{3 are} independently selected from optionally substituted alkyl radicals, optionally substituted aryl radicals, CN and a hydrogen atom and R ⁴ and R ^{5 are} independently selected from -C (O) OR ⁷ , -C (O) R ⁷ , -C (O) NR ⁸ R ⁹ and CN, wherein R ⁷ , R ⁸ and R ^{9 are} as in claim 1 are defined. A precursor according to claim 1, wherein the sensitizer is a 1,4-dihydropyridine of the formula (Ia)

wherein R ¹ and R ^{6 are} as defined in claim 1, the radicals R ^8a to R ^8d and R ^9a to R ^{9d are} independently selected from hydrogen, alkyl radicals and aryl radicals, where 2 radicals R ⁹ and R ⁸ of adjacent ring carbon atoms also each Z is independently selected from CR ¹³ ₂ , O, S, and NR ¹³ , and each R ^{13 is} independently a hydrogen atom, an alkyl, aralkyl, or aryl radical; of the formula (Ib)

wherein R ¹ and R ^{6 are} as defined above, R ^10a to R ^10d and R ^11a to R ^{11d are} independently selected from hydrogen, alkyl, aryl, aralkyl, halogen, CN, NR ¹³ ₂ , C (O) OR ¹³ and OR ¹³ in which two radicals R ¹¹ and R ¹⁰ of adjacent ring carbon atoms can also together form an unsaturated carbocyclic or heterocyclic ring or fused aromatic ring, and each R ¹³ independently represents a hydrogen atom, an alkyl radical, aryl radical or aralkyl radical of the formula ( Ic)

wherein R ¹ , R ³ , R ⁵ and R ^{6 are} as defined above, R ^9a to R ^{9f are} independently selected from hydrogen, alkyl, aryl, aralkyl, halogen, CN, NR ¹³ ₂ , C (O) OR ¹³ and OR ¹³ , wherein 2 R ⁹ of adjacent ring carbon atoms may also together form a saturated or unsaturated carbocyclic or heterocyclic ring or fused aromatic ring, and R ^{13 is} independently hydrogen, alkyl, aryl or aralkyl, of the formula (Id )

wherein each of R ¹ , R ² , R ³ , R ⁴ and R ^{5 is} independently defined as in claim 1 and Y is selected from alkanediyl and arylene of formula (Ie)

where R ² , R ⁴ , R ⁵ and R ^{6 are} as defined above and the radicals R ^9a to R ^{9f are} as defined above the radicals R ^9a to R ^{9d of} formula (Ia) of the formula (If)

where R ² , R ⁴ , R ⁵ and R ^{6 are} as defined above and the radicals R ^9a to R ^{9h are} as defined above the radicals R ^9a to R ^9d of formula (Ia) and of the formula (Ig)

wherein R ² , R ⁴ , R ⁵ and R ^{6 are} as defined above, the radicals R ¹¹ to R ^11d independently of hydrogen, alkyl radicals, aryl radicals, aralkyl radicals, halogen atoms, CN, NR ¹³ ₂ , C (O) OR ¹³ and OR ¹³ , wherein two adjacent radicals R ^{11 may} together also form an unsaturated carbocyclic or heterocyclic ring or fused aromatic ring, and R ¹³ independently represents a hydrogen atom, an alkyl radical, an aryl radical or an aralkyl radical. precursor according to one the claims 1 to 3, wherein the co-initiator (iii) is selected from 2,2-bis (2-chlorophenyl-4,5,4 ', 5'-tetraphenyl-2'H [1,2'] biimidazole and 2 , 2'-bis (2-chlorophenyl) -4,4 ', 5,5'-tetra (m-methoxyphenyl) biimidazole. precursor according to one the claims 1 to 4, wherein the composition additionally comprises one or more chain transfer agents contains. precursor according to one the claims 1 to 5, wherein the carrier is an aluminum foil or plate acts. precursor according to claim 6, wherein the aluminum plate or foil prior to coating at least one Treatment, selected from roughening, anodizing and hydrophilizing. precursor according to one of the claims 1 to 7, wherein the precursor Furthermore having an oxygen barrier cover layer. Process for imaging a negative working precursor a lithographic printing plate comprising (a) Provide one as in any of the claims 1 to 8 defined negative-working precursor of a lithographic printing plate; (B) imagewise irradiation of the precursor with UV radiation; (c) optionally heating the imagewise irradiated precursor; (D) Remove the non-irradiated areas of the coating with a aqueous alkaline Developer; (e) optionally heating and / or flood exposure of the developed precursor. Method according to claim 9, wherein the imagewise exposure to UV radiation of a wavelength in the range of 250-450 nm. Illustrated lithographic printing plate available after the method of claim 9 or 10.