DE602004009227T2 - Heat sensitive planographic printing plate precursor - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION

The The present invention relates to a positive working lithographic Printing plate precursor, which is an aqueous-alkaline Development requires and an infrared dye with a polysiloxane group contains.

GENERAL PRIOR ART

at Lithographic printing machines use a so-called Druckmaster like a printing plate mounted on a drum of the printing press. The master surface enters lithographic image and a print is obtained by first printing ink applied to the image and then the color of the master a receiving material, usually paper, is transmitted. In conventional lithographic printing is both ink and fountain solution water-based on the lithographic image, made of oleophilic (or hydrophobic, i.e., ink-receptive, water-repellent) And hydrophilic (or oleophobic, i.e. hydrophilic, ink-repelling) Areas constructed, appropriate. In so-called driographic The lithographic image consists of ink-receptive and ink-repellent (i.e. H. ink-repelling) Areas and will be during of driographic printing, just apply printing ink to the master.

print Master are usually after the so-called computer-to-film process (data-driven film production) obtained where different pre-presses like the choice of typeface, scanning, making color separations, framing, trapping, layout and imposition done digitally and each color separation on a gel graphic film is exposed. After development, the film as Mask for the exposure of an image-forming material, as a printing plate precursor designated, used and after the development of the plate becomes obtained a printing plate, which is used as a master.

A typical printing plate precursor for Computer-to-film method contains a hydrophilic carrier and an imaging layer with radiation-sensitive polymers Layers containing UV sensitive diazo compounds, dichromate sensitized contain hydrophilic colloids and a variety of synthetic photopolymers. In particular, diazosensitized layer dressings are becoming widespread used. For imagewise exposure, usually with the help of a film mask in a UV contact copying machine the exposed image areas are insoluble and the non-exposed areas remain soluble in aqueous alkaline developer. The printing plate is then Developed with the developer in the non-exposed areas to remove contained diazonium salt or diazo resin. The illuminated Areas thus form the image areas (ie the printing areas) of the printing master and thus become such printing plate precursors as "negative working" called. There are also positive-working materials in which the exposed Areas forming non-printing areas, e.g. B. plates with a novolak naphthoquinone diazide coating, which is only exposed in the Areas in the developer solved becomes.

Except the The above radiation-sensitive materials are also heat-sensitive Printing plate precursors known. Such materials include the Advantage of their daylight resistance and are particularly suitable for use in the so-called computer-to-plate method (direct digital plate imaging), where the plate precursor is direct is exposed, d. H. without the use of a film mask. Usually will the material with heat applied or exposed to infrared light and the generated thereby Heat dissolves you (physical) chemical process such as ablation, polymerization, Insolubilization by cross-linking of a polymer or coagulation the particles of a thermoplastic polymer latex and solubilization by destruction intermolecular interactions.

In US 5,466,557 there is described a positive-working printing plate precursor sensitive to both ultraviolet (UV) and infrared (IR) light but not to visible light, and a support and coating containing an aqueous-alkaline-developer-soluble oleophilic polymer and an aqueous solution latent Brönsted acid contains.

In EP-A 864 420 there is described a positive-working heat-sensitive printing plate precursor containing a support, a first layer containing an oleophilic aqueous-alkaline-developer-soluble polymer, and an IR-sensitive cover layer whose permeability to or solubility in the aqueous alkaline developer is changed by IR exposure becomes.

In WO 97/39894 there is described a positive-working heat-sensitive printing plate precursor, which is sensitive to infrared light but not to ultraviolet light, and consists of a support and an IR-sensitive coating containing an aqueous-alkaline-developer-soluble oleophilic polymer and a solubilizer that reduces the solubility of the polymer in the developer.

In WO 99/21725 and WO 99/21715 there is described a positive-working heat-sensitive printing plate precursor whose coating contains a compound which enhances the resistance of the coating to developer. The compound is selected from the group consisting of poly (alkylene oxide), siloxanes and esters or amides of polyhydric alcohols.

In US 5,491,046 A method of imaging a positive-working and / or negative-working lithographic printing plate precursor is described wherein the image-forming layer contains a resole resin, a novolak resin, a latent Bronsted acid and an IR absorber.

In EP 1 162 078 there is described an imaging material comprising a substrate and an image-forming layer disposed on the substrate containing an infrared dye having at least one surface orientation group as a substituent for improving the sensitivity and / or image-forming ability of the imaging material.

In EP 1 256 444 EP-A-0 375 911 discloses a heat-sensitive lithographic printing plate precursor comprising a coating which sequentially contains a first layer containing an oleophilic aqueous alkali-soluble resin and a second layer capable of preventing penetration of the developer in unexposed areas; second layer comprises a water-repellent compound selected from the group consisting of a polymer having siloxane monomer units and / or perfluoroalkyl monomer units and a block copolymer or graft copolymer having a poly (alkylene oxide) block or oligo (alkylene oxide) block and a polymer or oligomer having siloxane monomer units and / or perfluoroalkyl monomer units and wherein the alkali solubility of the coating is increased by heating and the coating contains an infrared dye.

The major problems with those known from the prior art Materials are (i) the weak differentiation between the development kinetics the exposed and unexposed areas, d. H. the dissolution of the exposed coating parts in the developer is not completely finished at the moment that even the unexposed Coating parts begin to dissolve in the developer, and (ii) diffusion of heat into the substrate, resulting in a reduction in the sensitivity of the printing plate precursor brings with it. this leads to to deductions low quality with blurred edges, toning (color attraction in exposed areas) and close development latitude.

BRIEF PRESENTATION OF THE PRESENT INVENTION

task The present invention is to provide a positive working one lithographic printing plate precursor with high differentiation between exposed and unexposed areas and high sensitivity. Solved These objects are achieved by the material defined in claim 1 and in the subclaims defined specific embodiments. Thanks to using a water-repellent compound in the second Layer of coating and of infrared dyes with specific Substituents that the compatibility of the dye with the second Layer of the coating will improve during infrared exposure generated heat concentrated in the second layer.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The lithographic printing plate precursor of the invention contains a support having a hydrophilic surface and a coating applied thereover. The coating comprises at least two layers, referred to as first and second layers in the present invention, the first layer being closest to the support, ie, located between the support and the second layer. The printing plate precursor is positive working, that is, after exposure and development, the exposed areas of the coating are removed from the support to form hydrophilic (non-printing) areas, while the unexposed coating is not removed from the substrate and forms an oleophilic (printing) area. The second layer is considered to serve as a barrier layer which prevents permeation of the aqueous alkaline developer into the oleophilic resin in the unexposed areas of the first layer. In exposed areas, the blocking function of the second layer may be smaller as a result of the exposure, and the dissolution of the coating in these areas may occur more rapidly upon immersion of the coating in aqueous alkaline developer. This attenuation of the blocking function caused by the exposure the second layer can, for. B. by measuring the induced by swelling of the oleophilic resin water absorption of both an exposed and unexposed sample to be checked. Typically, the exposed sample absorbs a small amount of water while the mean water uptake of unexposed samples is zero within a statistical error.

The blocking function of the second layer is based on the presence of a water-repellent compound. Suitable examples of such compounds are polymers with siloxane units and / or perfluoroalkyl units or block or graft copolymers with a poly (alkylene oxide) block or oligo (alkylene oxide) block and a block of polysiloxane units or oligosiloxane units and / or perfluoroalkyl units. The water-repellent polymer may be present in an amount between e.g. B. 0.5 and 15 mg / m ² , preferably between 0.5 and 10 mg / m ² , more preferably between 0.5 and 5 mg / m ² and most preferably between 0.5 and 2 mg / m ² be used. Depending on the hydrophobic / oleophobic degree of the compound, higher or lower amounts are also suitable. If the water-repellent polymer is also color-repellent, the use of amounts above 15 mg / m ² can lead to a weak color attraction of the unexposed areas. In contrast, an amount below 0.5 mg / m ² can lead to an unsatisfactory development latitude, ie the exposed areas are not fully developed at the moment that the unexposed areas begin to develop.

in der o, p, q, r und s eine ganze Zahl von mehr als 1 bedeuten.The block having the siloxane and / or perfluoroalkyl moieties may be a linear, branched, cyclic or complex crosslinked polymer or copolymer. The perfluoroalkyl moiety is z. A - (CF ₂ ) unit. The number of such units may be more than 10, preferably more than 20. The term "polysiloxane compound" includes any compound containing more than one siloxane group -Si (R, R ') - O- in which R and R' represent an optionally substituted alkyl or aryl group Preferred siloxanes are phenylalkylsiloxanes and dialkylsiloxanes The number of siloxane groups -Si (R, R ') - O- in (co) polymer is at least 2, preferably at least 10, more preferably at least 20. It may be less than 100, preferably less than 60 The alkylene oxide block preferably contains units of the formula -C _n H ₂ nO- in which n is preferably an integer between 2 and 5. The group -C _n H _2n - may contain straight or branched chains The alkylene oxide block group may also have optional substituents Preferred embodiments and specific examples of such polymers are described in WO 99/21725 , A suitable water-repellent polysiloxane compound is preferably a random copolymer or block copolymer having siloxane groups and alkylene oxide groups, with an appropriate number between about 15 and 25 siloxane units and between 50 and 70 alkylene oxide groups. Preferred polysiloxane is a copolymer of dimethyldichlorosilane, ethylene oxide and propylene oxide. Specific compounds are:

in which o, p, q, r and s are an integer greater than 1.

In Formula I is one of ethylene oxide units and propylene oxide units existing polyalkylene oxide grafted onto a polysiloxane block. In formula II are long chain, from ethylene oxide units and propylene oxide units existing alcohols grafted onto a trisiloxane group.

The second layer may be both the oleophilic resin and the water repellent compound contain. However, the starting point is that block or graft copolymers, which is a poly (alkylene oxide) block or oligo (alkylene oxide) block and a block of polysiloxane or oligosiloxane and / or perfluoroalkyl units abstain while the coating due to their bifunctional structure at the interface between the coating solution and position the air, automatically creating a separate layer form, which corresponds to the second layer of the invention, even when incorporated as part of the oleophilic coating solution be applied.

The water-repellent But connection can also be made from a separate solution the first layer to be applied. In this embodiment it may be beneficial to use in the second coating solution solvent to be able to use that in the first layer to dissolve contained ingredients, whereby a phase of highly concentrated water-repellent polymer is obtained on the material becomes.

While it is Applicants' wish not to be limited by any theoretical explanation of the effect of their printing plate precursor, it is believed that spreading of the second layer onto the first layer is reduced by exposure. This is called "thermal dehumidification", ie the surface tension of the polysiloxane decreases to such an extent under the action of the generated heat that the second layer breaks up and an incomplete layer is formed which no longer completely protects the first layer from the developer For example, removal of the polysiloxane by wiping can be measured by measuring the ratio of the ¹ H NMR signals of the siloxane to the signals of the phenolic resin of a sample before wiping with a cotton swab Compare wiping with the same ratio after wiping.

The oleophilic resin is preferably an aqueous developer-soluble polymer, especially before a polymer soluble in an aqueous alkaline developing solution having a pH between 7.5 and 14. Preferred polymers are phenolic resins, e.g. Novolac, resoles, polyvinyl phenols, and carboxyl-substituted polymers. Typical examples of such polymers are described in DE-A 4 007 428 . DE-A 4 027 301 and DE-A 4 445 820 ,

The Contains coating a polysiloxane-containing infrared dye, the material compared to at the exposure used IR light sensitive. The polysiloxane group can be a linear, branched, cyclic or complex cross-linked Be a group. The number of silicon atoms in the polysiloxane group may be more than 2, preferably 4 or more than 4. preferred Siloxane groups -Si (R, R ') - O- are groups in which R and R 'are one optionally substituted alkyl or aryl group. preferred Siloxane groups are phenylalkylsiloxanes and dialkylsiloxanes, e.g. As phenylmethylsiloxanes and dimethylsiloxanes. The infrared dye is preferably a compound with an absorption maximum in Wavelength range between 750 and 1,500 nm, making it insensitive to daylight Material is obtained for that its handling requires no darkroom. Under "opposite daylight insensitive material "is to understand that exposure to visible light is not essential solution the coating in the developer triggers.

Of the Sensitizing dye can be in the first layer, in the above discussed second layer or in any other layer be embedded. It is believed that the high hydrophobicity of the Infrared dye contained polysiloxane group the dye compatible with the water-repellent Makes connection and thus allows the dye to move faster in preferably the second layer, d. H. further away from the carrier, to position. As a result, the heat generated in the exposure in the concentrated second layer and achieved high sensitivity. The relationship the infrared absorbing compound in the coating is usually between 0.25 wt .-% and 10.0 wt .-%, more preferably between 0.5% by weight and 7.5% by weight.

in der:
a und b unabhängig voneinander eine ganze Zahl zwischen 0 und 4 bedeuten,
-L¹- und -L²- unabhängig voneinander eine zweiwertige Verbindungsgruppe bedeuten, wie Alkylen, Arylen, Heteroarylen, -(CH₂)_t-O-, -(CH₂)_t-NH-, -(Ck₂)_t-COO-, -(CH₂)_t-COO-(CH₂)_u-, -(CH₂)_t-OCO-, -(CH₂)_t-OCO-(CH₂)_u-, -(CH₂)_tCONH- oder -(CH₂)_t-CONH-SO₂- oder eine Kombination derselben,
-E¹ und -E² unabhängig voneinander eine neutrale, anionische oder kationische Endgruppe aus der Gruppe bestehend aus Alkyl, -H, -OH, -Cl, -Br, -F, -SiR^aR^bR^c (neutrale Gruppen), -SO₃ ^–, -SO₄ ^–, -PO₃ ^2–, -PO₄ ^2–, -COO^– (anionische Gruppen) und -[NR^dR^eR^f]⁺ (kationische Gruppe) bedeuten,
wobei R^a, R^b und R^c unabhängig voneinander eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten und
R^d, R^e und R^f unabhängig voneinander ein Wasserstoffatom oder eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten,
-A¹- und -A²- unabhängig voneinander -[Si(R^gR^h)-O]_m-, -C_vF_2v-, -[(CF₂)₂-O]_w- oder eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten,
wobei R^g und R^h unabhängig voneinander eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe, -[O-Si(R^aR^b)]_q-E¹ oder -[O-Si(R^aR^b)]_q-E² bedeuten,
wobei p₁ und p₂ 0 oder 1 bedeuten,
wobei t, u, q und m 1 oder eine ganze Zahl über 1 bedeuten,
wobei v und w 2 oder eine ganze Zahl über 2 bedeuten,
-Y¹- und -Y²- unabhängig voneinander ein oder zwei gegebenenfalls substituierte, zur Vervollständigung eines 5-gliedrigen oder 6-gliedrigen heterocyclischen Ringes benötigte Nichtmetallatome bedeuten,
-Z¹- und -Z²- unabhängig voneinander ein Wasserstoffatom oder eine Alkylgruppe oder gemeinsam die zur Vervollständigung eines 5-gliedrigen oder 6-gliedrigen Ringes benötigten Atome bedeuten,
R¹ und R² unabhängig voneinander ein Wasserstoffatom, eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe oder ein Halogenatom, -NO₂, -O-Rⁱ, -CO-Rⁱ, -CO-O-Rⁱ, -O-CO-Rⁱ, -CO-NRⁱR^j, -NRⁱR^j, -NRⁱ-CO-R^j, -NRⁱ-CO-O-R^j, -NRⁱ-CO-NR^jR^k, -SRⁱ, -SO-Rⁱ, -SO₂-Rⁱ, -SO₂-O-Rⁱ, -SO₂NRⁱR^j, eine Perfluoralkylgruppe oder eine Polysiloxangruppe bedeuten, wobei jede der besagten Gruppen gegebenenfalls eine oben als -E¹ und -E² definierte Endgruppe E umfassen kann und/oder zwei Nachbargruppen aus der Gruppe bestehend aus R¹, R², -Y¹- und -Y²- gemeinsam einen gegebenenfalls substituierten 5-gliedrigen oder 6-gliedrigen Ring bilden,
wobei Rⁱ, R^j und R^k unabhängig voneinander ein Wasserstoffatom oder eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten,
R³ einen Substituenten aus der Gruppe bestehend aus einem Wasserstoffatom, einem Halogenatom und einer gegebenenfalls substituierten Alkylgruppe, Alkenylgruppe, Arylgruppe, Aralkylgruppe, Perfluoralkylgruppe, Polysiloxangruppe, Aminogruppe, Thioalkylgruppe, Thioarylgruppe, Aryloxygruppe, Alkoxygruppe, Barbitursäuregruppe oder Thiobarbitursäuregruppe bedeutet,
X ein oder mehrere eventuelle Gegenionen aus der Gruppe bestehend aus Cl^–, Br^–, I^–, F^–, D-SO₃ ^–, D-SO₄ ^–, D-PO₄ ^2–, D-PO₃ ^2–, D-COO^–, D-[NR^oR^pR^q]⁺, ClO₄ ^– oder BF₄ ^– bedeutet,
wobei D Si(R^rR^sR^t)-[O-Si(R^uR^v)]n-, [(R^rR^sR^t)SiO]₃-Si-, C_jF_2j+1 CF₃-[(CF₂)₂-O]_i-, eine Alkylgruppe, eine Arylgruppe oder eine substituierte Arylgruppe bedeutet,
wobei n und i 1 oder eine ganze Zahl über 1 bedeuten,
wobei j 3 oder eine ganze Zahl über 3 bedeutet,
R^o, R^p und R^q unabhängig voneinander ein Wasserstoffatom oder eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten und
R^r, R^s, R^t, R^u und R^v unabhängig voneinander eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten,
vorausgesetzt, dass in obiger allgemeiner Formel III zumindest einer der folgenden Substituenten eine Polysiloxangruppe ist: -A¹-, -A²-, R¹, R², R³ oder X.Preferred infrared absorbing compounds for use in the present invention correspond to the following general formula III:

in the:
a and b independently of one another denote an integer between 0 and 4,
-L ¹ - and -L ² - independently of one another denote a divalent linking group, such as alkylene, arylene, heteroarylene, - (CH ₂ ) _t -O-, - (CH ₂ ) _t -NH-, - (Ck ₂ ) _t - COO-, - (CH ₂ ) _t -COO- (CH ₂ ) _u -, - (CH ₂ ) _t -OCO-, - (CH ₂ ) _t -OCO- (CH ₂ ) _u -, - (CH ₂ ) _t CONH- or - (CH ₂ ) _t -CONH-SO ₂ - or a combination thereof,
-E ¹ and -E ² independently represent a neutral, anionic or cationic terminal group selected from the group consisting of alkyl, -H, -OH, -Cl, -Br, -F, -SiR ^a R ^b R ^c (neutral groups); -SO ₃ ^- , -SO ₄ ^- , -PO ₃ ^2- , -PO ₄ ^2- , -COO ^- (anionic groups) and - [NR ^d R ^e R ^f ] ⁺ (cationic group),
wherein R ^a , R ^b and R ^c independently represent an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, and
R ^d , R ^e and R ^f independently of one another denote a hydrogen atom or an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group,
-A ¹ - and -A ² - independently of one another - [Si (R ^g R ^h ) -O] _m -, -C _v F _2v -, - [(CF ₂ ) ₂ -O] _w - or an optionally substituted alkyl group , Alkenyl group, aryl group or aralkyl group,
wherein R ^g and R ^h are each independently an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, - [O-Si (R ^a R ^b )] _q -E ¹ or - [O-Si (R ^a R ^b )] _q - E ² mean
where p ₁ and p ₂ denote 0 or 1,
where t, u, q and m are 1 or an integer greater than 1,
where v and w are 2 or an integer greater than 2,
-Y ¹ - and -Y ² - independently of one another mean one or two unsubstituted, non-metal atoms required to complete a 5-membered or 6-membered heterocyclic ring,
-Z ¹ - and -Z ² - independently of one another denote a hydrogen atom or an alkyl group or together denote the atoms required to complete a 5-membered or 6-membered ring,
R ¹ and R ² independently represent a hydrogen atom, an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group or a halogen atom, -NO ₂ , -OR ⁱ , -CO-R ⁱ , -CO-OR ⁱ , -O-CO-R ⁱ , -CO-NR ⁱ R ^j , -NR ⁱ R ^j , -NR ⁱ -CO-R ^j , -NR ⁱ -CO-OR ^j , -NR ⁱ -CO-NR ^j R ^k , -SR ⁱ , - SO-R ⁱ , -SO ₂ -R ⁱ , -SO ₂ -OR ⁱ , -SO ₂ NR ⁱ R ^j , a perfluoroalkyl group or a polysiloxane group, each of said groups optionally having an above as -E ¹ and -E ² may comprise defined end group E and / or two neighboring groups from the group consisting of R ¹ , R ² , -Y ¹ - and -Y ² - together form an optionally substituted 5-membered or 6-membered ring,
wherein R ⁱ , R ^j and R ^k independently represent a hydrogen atom or an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group,
R ^{3 represents} a substituent selected from the group consisting of a hydrogen atom, a halogen atom and an optionally substituted alkyl group, alkenyl group, aryl group, aralkyl group, perfluoroalkyl group, polysiloxane group, amino group, thioalkyl group, thioaryl group, aryloxy group, alkoxy group, barbituric acid group or thiobarbituric acid group,
X is one or more possible counterions from the group consisting of Cl ^- , Br ^- , I ^- , F ^- , D - SO ₃ ^- , D - SO ₄ ^- , D - PO ₄ ^2- , D - PO ₃ ^2- , D -COO ^-, D- [NR ^o R ^p R ^{q] +,} ClO ₄ ^- or BF ₄ ^- means
where D Si (R ^r R ^s R ^t ) - [O-Si (R ^u R ^v )] n-, [(R ^r R ^{s t} ) SiO] ₃ -Si, C _j F _{2j + 1} CF ₃ - [(CF ₂ ) ₂ -O] _i -, an alkyl group, an aryl group or a substituted aryl group,
where n and i are 1 or an integer greater than 1,
where j is 3 or an integer greater than 3,
R ^o , R ^p and R ^q independently represent a hydrogen atom or an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, and
R ^r , R ^s , R ^t , R ^u and R ^v independently of one another are an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group,
provided that in general formula III above at least one of the following substituents is a polysiloxane group: -A ¹ -, -A ² -, R ¹ , R ² , R ³ or X.

In the embodiment, in which the infrared dye is negatively or positively charged, to neutralize the compound, a counterion X is reacted with opposite Charge needed. The dye may be anionic or cationic because the chromophore and / or polysiloxane-containing substituents on the Chromophore and / or other substituents on the chromophore electrical can be loaded. The charge unit of the dye is the sum of the Positive and / or Negative charges of the substituents on the dye determined, wherein the dye one or more counterions with the above sum corresponding, contains opposite charge, to neutralize the dye. The charge unit of the counterions may be monovalent or multivalent and / or positive or negative.

In the embodiment in which -E ¹ and -E ^{1 are} a neutral end group such as an alkyl group, -H, -OH, -F or -SiR ^a R ^b R ^c (and no other charged groups are present on the infrared dye) , the dye also contains a negatively charged counterion X, which neutralizes the positively charged infrared dye. If, on the other hand, one of the end groups is an anionic group, such as -SO ₃ ^- , -SO ₄ ^- or -COO ^- (and if the other end group is a neutral group and no other charged groups are present on the infrared dye), there is no need for a counterion. One of the end groups may be a cationic group, such as a - [NR ^a R ^b R ^c ] ⁺ group. In such a case the dye carries a single counterion with two negative charges (e.g. D-PO ₄ ^2-, D-PO ₃ ^2-.) Or two monovalent negatively charged counter ions (such as Cl ^-., Br ^-, I ^-, F ^- , D-SO ₃ ^- , D-SO ₄ ^- , D-COO ^- , ClO ₄ ^- or BF ₄ ^- ). Depending on the nature of the end groups -E ¹ and -E ¹ and their charge unit, one does not need one or more counterions to neutralize the infrared dye.

In the embodiment in which R ^{3 is} a negatively charged substituent, e.g. B. a negatively charged barbituric acid group means, and there are no other negatively or positively charged substituents on the infrared dye, a zwitterion is obtained. In this case, the sum of the charge of the dye is zero and is present on the dye no counterion.

in der R⁴ und R⁵ unabhängig voneinander eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Cycloalkylgruppe, Arylgruppe oder Aralkylgruppe oder eine Perfluoralkylgruppe oder Polysiloxangruppe bedeuten und jede dieser Gruppen gegebenenfalls eine oben als -E¹ und -E² definierte Endgruppe E enthalten kann. Die negativ geladene Barbitursäuregruppe ist über * an die Heptamethingruppe gebunden.A negatively charged barbituric acid group has the following formula:

in which R ⁴ and R ⁵ independently of one another are an optionally substituted alkyl group, alkenyl group, cycloalkyl group, aryl group or aralkyl group or a perfluoroalkyl group or polysiloxane group and each of these groups may optionally contain an end group E defined above as -E ¹ and -E ² . The negatively charged barbituric acid group is linked to the heptamethine group via *.

Suitable subclasses of the above infrared dyes correspond to the following formulas:

In the above formulas IV to XIV, p ₁ , p ₂ , a, b, -L ¹ -, -L ² -, -A ¹ -, -A ² -, -E ¹ , -E ² , R ¹ , R ² , R ³ , -Y ¹ -, -Y ² -, -Z ¹ , -Z ² and X denote the meaning assigned to these symbols in the above formula III and R ⁴ and R ^{5 have} the meaning given to these radicals above, provided that in that at least one of the following substituents is a polysiloxane group: -A ¹ -, -A ² -, R ¹ , R ² , R ³ , R ⁴ , R ⁵ or X.

in denen:
p₁, p₂, a, b, -L¹-, -L²-, -E¹, -E², -A¹-, -A²-, -Y¹-, -Y²-, -Z¹, -Z², -R³ und X die diesen Symbolen in obiger Formel III zugemessene Bedeutung haben,
c und d unabhängig voneinander 0, 1 oder 2 bedeuten und
R⁶ bis R⁹ unabhängig voneinander jeweils eine wie oben für R¹ und R² definierte Gruppe bedeuten,
unter der Voraussetzung, dass zumindest einer der folgenden Substituenten eine Polysiloxangruppe ist: -A¹-, -A²-, R³, R⁶ bis R⁹ oder X.Other suitable subclasses of infrared dyes correspond to formulas in which two R ¹ -negbar groups or two R ² -negbar groups form an optionally substituted phenyl group fused with another phenyl group of the dye. Accordingly, therefore, any of the formulas III to XIV, which comprises such a phenyl group, is suitable as a dye for the precursor according to the invention. Two preferred embodiments of such dyes correspond to the formulas XV and XVI:

in which:
p ₁ , p ₂ , a, b, -L ¹ -, -L ² -, -E ¹ , -E ² , -A ¹ -, -A ² -, -Y ¹ -, -Y ² -, -Z ¹ , -Z ² , -R ³ and X have the meaning given to these symbols in formula III above,
c and d are independently 0, 1 or 2 and
R ⁶ to R ^9, independently of one another, each represent a group as defined above for R ¹ and R ² ,
with the proviso that at least one of the following substituents is a polysiloxane group: -A ¹ -, -A ² -, R ³ , R ⁶ to R ⁹ or X.

In the formulas IV to XIV two R ¹ Nachbargruppen and / or two R ² Nachbargruppen a optionally substituted, fused phenyl group and such subclasses also fall within the scope of the present invention.

Further preferred subclasses of infrared dyes correspond to formula III, in which the polysiloxane group is covalently bonded to the dye and / or contained in the possible counterion X. The indices / substituents p ₁ , p ₂ , -L ¹ , -L ² , -E ¹ , -E ² , -A ¹ -, -A ² -, -Y ¹ -, -Y ² -, R ¹ , R ² , R ³ , -Z ¹ , -Z ² and X have the meaning assigned to these symbols in formula III above.

• • -A¹-, -A²-, R¹, R² und R³ keine Polysiloxangruppen bedeuten können und
• • X eine Polysiloxangruppe enthält.

Further preferred subclasses of infrared dyes correspond to formula III, in which the polysiloxane group is not covalently bound to the dye, but is contained in the counterion X. The indices / substituents p ₁ , p ₂ , -L ¹ , -L ² , -E ¹ , -E ² , -A ¹ -, -A ² -, -Y ¹ -, -Y ² -, R ¹ , R ² , R ³ , -Z ¹ , -Z ² and X have the meaning assigned to these symbols in formula III above, provided that:

• • -A ¹ -, -A ² -, R ¹ , R ² and R ^{3 can} not denote polysiloxane groups and
• • X contains a polysiloxane group.

in denen:
R¹⁰ -(CH₂)_e-Si-[OSi(R¹¹R¹²R¹³)]₃ oder
-(CH₂)_e-OCO-(CH₂)_f-[Si(R¹⁴R¹⁵)-O]_g-(CH₂)_h-CH₃ bedeutet,
R⁴ und R⁵ die diesen Resten oben zugemessene Bedeutung haben,
R¹¹, R¹², R¹³, R¹⁴ und R¹⁵ unabhängig voneinander eine gegebenenfalls substituierte Alkylgruppe, Alkenylgruppe, Arylgruppe oder Aralkylgruppe bedeuten und
e, f, g und h 1 oder eine ganze Zahl über 1 bedeuten.Further preferred subclasses of infrared dyes correspond to the following formulas XVII and XVIII:

in which:
R ^{10 is} - (CH ₂ ) _e -Si- [OSi (R ¹¹ R ¹² R ¹³ )] ₃ or
- (CH ₂ ) _e -OCO- (CH ₂ ) _f - [Si (R ¹⁴ R ¹⁵ ) -O] _g - (CH ₂ ) _h -CH ₃
R ⁴ and R ^{5 have} the meaning given above to these radicals,
R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ independently represent an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, and
e, f, g and h are 1 or an integer greater than 1.

Specific examples of preferred infrared dyes for use in the present invention include the following compounds:

In addition to the preferred polysiloxane-containing infrared dyes, the coating may contain additional infrared dyes such as cyanine dyes or cyanine pigments such as carbon black. Examples of suitable infrared dyes are described in e.g. B. EP-A 823 327 . EP-A 978,376 . EP-A 1 029 667 . EP-A 1 053 868 . EP-A 1 093 934 . WO 97/39894 and WO 00/29214 ,

The first layer may further contain other ingredients, such as additional binders which increase the run length of the plate, colorants, development inhibitors, as described in U.S. Patent No. 5,376,842 WO 97/39894 and EP-A 823 327 , or development accelerators such as 3,4,5-trimethoxybenzoic acid. The colorants are preferably dyes which remain in the unexposed areas of the coating during development and are washed away from the exposed areas to form a visible image. Preferably, such indicator dyes do not render the coating susceptible to visible light.

Suitable development accelerators are described in, for. B. EP-A 933,682 , Such compounds promote dissolution by reducing the dissolution time of the first layer. For example, cyclic acid anhydrides, phenols or organic acids are useful for improving the developability in aqueous solutions. Examples of the cyclic acid anhydride include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 3,6-endoxy-4-tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, maleic anhydride, chloromaleic anhydride, .alpha.-phenylmaleic anhydride, succinic anhydride and pyromellitic acid, as described in U.S. Pat US Pat. No. 4,115,128 , Examples of the phenols include bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,4,4'-trihydroxybenzophenone, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, 4,4 ', 4 "-trihydroxytriphenylmethane and 4 , 4 ', 3 ", 4"-tetrahydroxy-3,5,3',5'-tetramethyltriphenylmethane and the like. Examples of the organic acids are sulfonic acids, sulfinic acids, alkylsulfuric acids, phosphonic acids, phosphates and carboxylic acids, as described in, for. B. JP-A 60-888 942 and JP-A 2-96755 , Specific examples of these organic acids include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, p-toluenesulfinic acid, ethylsulfuric acid, phenylphosphonic acid, phenylphosphinic acid, phenylphosphate, diphenylphosphate, benzoic acid, isophthalic acid, adipic acid, p-toluic acid, 3,4-dimethylmethoxybenzoic acid, phthalic acid, terephthalic acid, 4- Cyclohexene-1,2-dicarboxylic acid, erucic acid, lauric acid, n-undecanoic acid and ascorbic acid. The amount of cyclic acid anhydride, phenol or organic acid in the image-forming composition is preferably between 0.05 and 20% by weight.

Of the carrier has a hydrophilic surface on or is provided with a hydrophilic layer. The carrier can a sheet-like material such as a plate or a cylindrical one Element like a sleeve-shaped plate be pushed around a printing drum of a printing press can. Preferably, the carrier a metal carrier like a carrier made of aluminum or stainless steel.

A particularly preferred lithographic support is an electrochemically roughened and anodized aluminum support. The anodized aluminum support may be subjected to processing to improve the hydrophilic properties of the support surface. For example, by processing the support surface with a sodium silicate solution at elevated temperature, e.g. B. 95 ° C, silicate. Alternatively, a phosphate processing may be performed wherein the alumina surface is processed with an optional further inorganic fluoride-containing phosphate solution. Further, the alumina surface may be rinsed with a citric acid or citrate solution. This treatment can be carried out at room temperature or at a slightly elevated temperature between about 30 ° C and 50 ° C. Another interesting method is to rinse the alumina surface with a bicarbonate solution. Further, the alumina surface may be processed with polyvinylphosphonic acid, polyvinylmethylphosphonic acid, phosphoric acid esters of polyvinyl alcohol, polyvinylsulfonic acid, polyvinylbenzenesulfonic acid, sulfuric acid esters of polyvinylalcohol and acetals of polyvinylalcohols formed by reaction with a sulfonated aliphatic aldehyde. Further, it is obvious that one or more of these post treatments may be performed separately or in combination. More detailed descriptions of these treatments can be found in GB-A 1 084 070 . DE-A 4 423 140 . DE-A 4 417 907 . EP-A 659 909 . EP-A 537 633 . DE-A 4 001 466 . EP-A 292 801 . EP-A 291 760 and U.S. Patent 4,458,005 ,

To a further embodiment can the carrier also a flexible carrier which is coated with a hydrophilic layer, hereinafter referred to as "primer layer" is. The flexible carrier is z. As paper, a plastic film, a thin aluminum substrate or a laminate of these materials. Preferred examples of plastic films are a film of polyethylene terephthalate, polyethylene naphthalate, Cellulose acetate, polystyrene, polycarbonate, etc. The plastic film carrier can opaque or translucent be.

The Primer layer is preferably a crosslinked hydrophilic layer, made of a hydrophilic, with a hardener such as formaldehyde, glyoxal, Polyisocyanate or a hydrolyzed tetraalkyl orthosilicate crosslinked Binder is obtained. The latter crosslinking agent becomes special prefers. The strenght the hydrophilic primer layer can vary between 0.2 and 25 μm and is preferably between 1 and 10 microns.

The hydrophilic binder for use in the primer layer z. A hydrophilic (co) polymer such as homopolymers and copolymers of vinyl alcohol, acrylamide, methylolacrylamide, methylolmethacrylamide, Acrylic acid, methacrylic acid, Hydroxyethyl acrylate, hydroxyethyl methacrylate or maleic anhydride vinylmethyl ether copolymers. The hydrophilicity of the used (co) polymer or (co) polymer mixture is preferably higher or equal to the hydrophilicity of at least 60% by weight, preferably to 80% by weight hydrolyzed polyvinyl acetate.

The Lot of hardener, in particular tetraalkylorthosilicate, is preferably at least 0.2 parts by weight per part by weight of hydrophilic binder more preferably between 0.5 and 5 parts by weight, especially preferably between 1 part by weight and 3 parts by weight per part by weight hydrophilic binder.

The hydrophilic primer layer may also contain substances that improve the mechanical strength and porosity of the layer. Colloidal silica can be used for this purpose. The colloidal silica may be in the form of any commercial water dispersion of colloidal silica having, for example, an average particle size of up to 40 nm, e.g. B. 20 nm, are used. In addition, inert particles can be added with a larger particle size than the colloidal silica, z. As silica, as described in J. Colloid and Interface Sci., Volume 26, 1968, pages 62 to 69, described by Stöber or particles having an average diameter of at least 100 nm, which are particles of titanium dioxide or other heavy metal oxides. By embedding these particles, the surface of the hydrophilic primer layer is given a uniform rough texture with microscopic peaks and valleys that serve as reservoirs for water in background areas.

Specific examples of suitable hydrophilic primer layers for use in the present invention are disclosed in U.S. Patent Nos. 4,135,359 EP-A 601 240 . GB-P 1 419 512 . FR-P 2 300 354 . U.S. Pat. No. 3,971,660 and U.S. Patent 4,284,705 ,

Particularly preferred is a film carrier which is provided with an adhesion-promoting layer, also referred to as carrier layer. Particularly suitable adhesion promoting layers for use in the present invention include a hydrophilic binder and colloidal silica, as described in US 5,256,237 EP-A 619 524 . EP-A 620 502 and EP-A 619 525 , The amount of silica in the adhesion-promoting layer is preferably between 200 mg / m ² and 750 mg / m ² . Further, the ratio of silica to hydrophilic binder is preferably more than 1 and the specific surface area of the colloidal silica is preferably at least 300 m ² / g, more preferably at least 500 m ² / g.

The printing plate precursor according to the invention can by means of z. B. an LED or a laser head are exposed. Preference is given to one or more lasers or a laser diode. Preferred for exposure is infrared light having a wavelength between about 750 and about 1500 nm, preferably a laser such as a semiconductor laser diode, a Nd: YAG laser or a Nd: YLF laser. The laser power required depends on the sensitivity of the imaging layer, the pixel dwell time of the laser beam, which is determined by the beam width (a typical value at 1 / e ^{2 of} the maximum intensity is between 10 and 25 μm in modern platesetters), the scanning speed and the resolution of the Gelichters (ie the number of addressable pixels per unit length, often expressed in dots per inch or dpi / typical values are between 1,000 and 4,000 dpi).

It are two types more common Laser imager, d. H. an inner drum plate setter (ITD platesetter) and an outer drum plate setter (XTD) plate-. ITD plate-setters for thermal plates usually by very high scanning speeds up to 1,500 m / s and need sometimes a laser power of several watts. The Agfa Galileo T (trademark of Agfa-Gevaert N.V.) is a typical example for one Platesetter of ITD technology. XTD platesetters work at a lower scanning speed, which is usually between 0.1 m / s and 10 m / s, and have a typical laser power per laser beam between 20 mW and 500 mW. The family of Creo Trendsetter Platesetters (trademark of Creo) and the family the Agfa Excalibur Platesetter (trademark of Agfa-Gevaert N.V.) both work on the basis of XTD technology.

The known platesetters are suitable for use as off-press gelators. The advantage of this application is that it reduces press downtime. XTD platesetter configurations are also suitable for on-press exposure, which has the advantage of immediate registration of the plate into a multi-color press. More detailed technical information on on-press-gelators are z. In US 5,174,205 and US 5,163,368 described.

in the Development step will be the unexposed areas of the coating by immersion in an aqueous-alkaline Developer removed, optionally in combination with mechanical Wipe, z. B. by means of a brush roller. The step of development may include a drying step, a rinsing step, connect a gumming step and / or a post-bake step.

The printing plate thus obtained is suitable for conventional, so-called wet offset printing, in which printing ink and fountain solution are applied to the plate. In another suitable printing method so-called single-fluid printing ink is used without fountain solution. Suitable single-fluid printing inks for use in the method according to the invention are described in US 4,045,232 and US 4,981,517 , In a most preferred embodiment, the single-fluid ink includes a paint phase, also referred to as a hydrophobic or oleophilic phase, and a polyol phase as described in U.S. Pat WO 00/32705 ,

EXAMPLES

Synthesis of infrared dyes

Synthesis of IR-1 Product 1 + Product 2 → IR-1

2 mol of product 1 and 1 mol of product 2 are dissolved in 7.5 l of acetonitrile and stirred at 70 ° C for 90 minutes. Then 17 l of acetonitrile are added and the reaction mixture is allowed to cool to room temperature. IR-1 is filtered off and dried.
(Yield = 46%) Synthesis of Intermediate 1 Product 3 + Product 4 → Product 1

One mole of product 4, 1.4 moles of product 3 and 1 mole of potassium iodide are added to 0.3 liters of sulfolane. The reaction mixture is stored at 150 ° C for 6 hours. The mixture is then cooled to room temperature and 2 l of methyl tert-butyl ether are added. After extraction with 10 l of water, 2 l of butyl acetate are added to the organic layer. The reaction mixture is stirred for 30 minutes and product 1 is filtered off and dried. (Yield = 21%) Synthesis of Intermediate 2 Product 5 + Product 6 → Product 2

One mole of product 5 and 3.5 moles of product 6 are added to 0.3 liters of ethyl acetate and the mixture is kept at 65 ° C. for 30 minutes. After addition of 0.75 l of methyl tert-butyl ether and 0.7 l of hexane, product 2 is filtered off and dried. (Yield = 55%) Synthesis of Intermediate 5 Product 6 + Product 7 → Product 5

1.13 moles of product 6 are added at room temperature to 1 mole of product 7 in 0.8 liters of toluene and 1 mole of acetic acid. Subsequently, 1.5 l of hexane are added and the reaction mixture is stirred for 1 hour at room temperature. Product 5 is filtered off and dried.
(Yield = 79%)

Synthesis of Intermediate 7 Product 8 + cyclopentanone → product 7

1 Mole of product 8, 1.1 moles of cyclopentanone, 0.07 moles of ammonium acetate and 0.15 l of methanol are mixed and heated under reflux for 4.5 hours. Subsequently 1 l of toluene is added and distilled off methanol and water. The obtained reaction solution is used to synthesize intermediate 5.

Synthesis of Intermediate 8 Product 9 + Product 10 → Product 8

1 One mole of product 9, 1 mole of product 10, 2 moles of acetic anhydride and 0.15 liters of acetic acid are allowed 2.5 hours at 90 ° C react with each other. After vacuum distillation of the acetic acid is Product 8 received.

Synthesis of Intermediate 9 Product 11 + Product 12 → Product 9

1 1 mol of product 11 is dissolved in 0.07 l of toluene, followed at 50 ° C 1 mol of product 12 is added. After evaporation of the solvent product 9 receive.

Synthesis of IR-2 Product 13 + Product 14 + Product 18 → IR-2

4 moles of product 14 and 2 moles of product 18 are stirred for 10 minutes at 80 ° C in 10 liters of toluene. At Finally, 1 mole of product 13 and 40 liters of toluene are added. The reaction mixture is refluxed for 45 minutes. After evaporation of the organic layer, the residual product is dissolved in a mixture of 5 l of toluene and 5 l of methanol. After addition of 40 l of methanol, IR-2 is filtered off and dried. (Yield = 50%)

Synthesis of Intermediate 13 Product 15 + Product 16 → Product 13

1 Mole of product 15, 1.1 moles of product 16 and 1.5 moles of potassium acetate in 4 l of methylene chloride and 6 l of methanol. The mixture is 1 hour stirred long at room temperature. Product 13 is filtered off and dried. (Yield = 30%)

Synthesis of Intermediate 15 Product 19 + Product 20 → Product 15

One Mixture of 2 moles of product 19, 1 mole of product 20, 4 liters of methanol, 0.5 l triethylamine and 0.4 l acetic anhydride will last 2 hours at 60 ° C touched. After subsequent Addition of 200 g of NaI and 4 l of methyl tert-butyl ether becomes product 15 filtered off and dried. (Yield = 25%)

Synthesis of Intermediate 19

1 Mol of product 3 and 0.1 mol of 2-bromoethanol are dissolved in 0.2 l sulfolane solved and 4 hours at 100 ° C kept. After addition of 1 liter of acetone, the product precipitates. product 19 is filtered off and dried. (Yield = 82%)

Synthesis of Intermediate 16 Product 29 + Product 10 → Product 16

One Mixture of 1 mole of product 29, 0.5 liters of toluene, 0.18 liters of acetic acid, 1.05 Mol of product 10 and 0.25 l of acetic anhydride are kept at 100 ° C for 2.5 hours kept. The reaction mixture is poured into a mixture of methanol and water, after which product 16 was filtered off and dried becomes. (Yield = 44%)

Synthesis of Intermediate 29 Product 17 + Product 18 → Product 29

2 Mole of product 17 and 1 mole of product 18 are stirred for 30 minutes at 90 ° C. The Reaction mixture is poured into a mixture of methanol and water, after which product 29 is filtered off and dried. (Yield = 28%)

Synthesis of IR-3 Product 14 + Product 18 + Product 24 → IR-3

4 moles of product 14, 10 liters of toluene and 2 moles of product 18 are stored at 80 ° C for 10 minutes. To then adding 1 mole of product 24 and 50 liters of toluene, the mixture is refluxed for 45 minutes. After evaporation of the organic layer 5 l of toluene and 5 l of methanol are added. After addition of 40 l of methanol, IR-3 is filtered off and dried. (Yield = 75%)

Synthesis of Intermediate 24 Product 25 + Product 16 → Product 24

8th l of methanol, 4 l of methylene chloride, 1 mol of product 25, 1 mol of product 16 and 1.5 moles of potassium acetate are allowed to stand at room temperature for 3 hours touched. After addition of methyl ethyl ketone, the product precipitates. product 19 is filtered off, washed with water and dried. (Yield = 67%)

Synthesis of Intermediate 25 Product 20 + Product 26 → Product 25

2 l of methanol, 0.25 l of triethylamine, 2 moles of product 26, 1 mol of product 20 and 0.2 l of acetic anhydride 2 hours at 60 ° C touched. Product 25 is filtered off and dried. (Yield = 40%)

Synthesis of Intermediate 26 2-Bromoethanol + product 27 → product 26

1 Mole of product 27 and 1.1 moles of 2-bromoethanol are dissolved in 2 liters of sulfolane solved and 4 hours at 100 ° C touched. After adding acetone drops the product out. Product 26 is filtered off and dried. (Yield = 85%)

Synthesis of Intermediate 20

10 Mole of dimethylformamide and 3 moles of phosphoryl chloride are heated to 65 ° C. Subsequently 1 mol of cyclopentanone is added dropwise to this mixture, after which the mixture 1 hour at 60 ° C touched becomes. The reaction mixture is in 2 l 7 moles of sodium acetate containing Poured water. Product 20 is filtered off and dried. (Yield = 60%)

Synthesis of IR-4 Product 28 + Product 18 + Product 24 → IR-4

4 Mole of product 28 and 2 moles of product 18 are added to 50 liters of toluene and the mixture was stirred at 80 ° C for 10 minutes. After subsequent addition of 1 mole of product 24 and 50 liters of toluene, the mixture is 45 minutes heated for a long time under reflux. After evaporation of the organic layer 500 l of hexane are added. The mixture is filtered off and the filtrate is evaporated. So will IR-4 received. (Yield = 11%)

Synthesis of IR-COMP1 Product 30 + Product 16 → IR-COMP1

1 mol of product 30 and 1 mol of product 16 are dissolved in 15 l of methanol and 7 l of methylene chloride. After addition of 2 moles of potassium acetate, the mixture is stirred for 3 hours at 40 ° C. After evaporation of the methylene chloride, COMP-1 is filtered off and dried.
(Yield = 46%)

Synthesis of Intermediate 30 Product 31 + Product 32 → Product 30

1 Mol of product 32 and 2 moles of product 31 become 2 liters of acetic anhydride and 2.2 mol of triethylamine. The mixture is kept for 2 hours stirred at room temperature. Subsequently 40 l of ethyl acetate are added and the product is filtered off and dried. (Yield = 30%)

Synthesis of Intermediate 31

Product 27 + n-butylbromide → product 31

1 Mole of product 27 and 2 moles of n-butyl bromide are allowed to stand for 4 hours 100 ° C in 0.5 l sulfolane stirred. product 31 is filtered off, washed with ethyl acetate and dried. (Yield = 61%)

Synthesis of Intermediate 32 Product 33 + Product 34 → Product 32

1 Moles of product 33 and 2 moles of product 34 are dissolved in 5 liters of acetone and 2 liters Water dissolved and stirred at room temperature for 1 hour. Product 32 is filtered off and dried. (Yield = 80%)

Examples 1 and 2

These Explain examples the use of polysiloxane-containing infrared dyes in a coating according to the invention, in the water repellent Compound is a polysiloxane-containing polymer.

Production of the carrier

A 0.30 mm thick aluminum foil is degreased by immersing the foil in an aqueous solution containing 5 g / l of sodium hydroxide at 50 ° C and rinsed with demineralized water. The film is then at a temperature of 35 ° C and a current density of 1200 A / m ² in an aqueous solution containing 4 g / l hydrochloric acid, 4 g / l of hydrobromic acid and 5 g / l aluminum ions, with alternating current roughened electrochemically to obtain a surface topography having an arithmetic mean roughness Ra of 0.5 μm.

To flush with demineralized water, the aluminum foil with a aqueous, 300 g / l sulfuric acid containing solution 180 s at 60 ° C etched and subsequently 30 s at 25 ° C rinsed with demineralised water.

Subsequently, the film is anodized at a temperature of 45 ° C, a voltage of about 10 V and a current density of 150 A / m ² for about 300 s in an aqueous solution containing 200 g / l of sulfuric acid to form an anodic, 3, 00 g / m ² Al ₂ O ₃ containing oxidation film, then washed with demineralized water, then processed in turn with a solution containing polyvinylphosphonic acid and a solution containing aluminum trichloride and finally rinsed 120 s at 20 ° C with demineralized water and dried.

Plate precursor materials

The solutions listed in Table 1 are applied in a wet thickness of 20 microns to the carrier prepared as above and dried at 130 ° C for 1 minute. The materials are then exposed at different energy density values varying between 80 mJ / cm ² and 200 mJ / cm ² (exposure intensity on the image plane) using a Creo Trendsetter 3244 (830 nm). Thereafter, the plates are developed by immersing for 60 seconds in a development tank filled with (Agfa-supplied aqueous alkaline) DP300 developer at a temperature of 25 ° C.

The Sensitivity to Infrared light of the various compositions corresponds to the minimum energy density adjustment needed to be used in areas those with an area coverage a 50s grid (@ 200 lpi) have been exposed, a 50% Reduction of the light absorption of the coating, wherein the measurement on the developed plate at the maximum wavelength of the Contrast dye takes place.

• * Alnovol SPN452 ist eine 40,5%ige Lösung in Dowanol PM (erhältlich durch Clariant),
• ** Triarylmethan-Farbstoff, erhältlich durch BASF,
• *** ein polysiloxanhaltiges Polymer, erhältlich durch Tego Chemie, Essen, Deutschland/10 gew.-%ige Lösung in Methoxypropanol,
• **** ein polysiloxanhaltiges Polymer, erhältlich durch Tego Chemie, Essen, Deutschland/10 gew.-%ige Lösung in Methoxypropanol.

The results in Table 1 show that the coating containing a polysiloxane-containing infrared dye has a higher sensitivity than the comparative coating in which the corresponding infrared dye does not contain a polysiloxane group. Table 1 Ingredients (g) Example 1 (required) Example 2 (see) tetrahydrofuran 25.76 25.76 Alnovol SPN452 * 6.59 6.59 methoxypropanol 16,98 16,98 IR-2 0.1 - IR COMP1 - 0.1 Flexo blue 630 ** 0.03 0.03 Tego Glide 410 *** 0.14 0.14 Tego Wet 265 **** 0.05 0.05 2,3,4-trimethoxy 0.36 0.36 IR sensitivity (mJ / cm ² ) 120 > 200

• * Alnovol SPN452 is a 40.5% solution in Dowanol PM (available from Clariant),
• ** triarylmethane dye, available from BASF,
• *** a polysiloxane-containing polymer, available from Tego Chemie, Essen, Germany / 10% by weight solution in methoxypropanol,
• **** a polysiloxane-containing polymer, available from Tego Chemie, Essen, Germany / 10% strength by weight solution in methoxypropanol.

Examples 3 and 4

These Explain examples the use of a polysiloxane-containing infrared dye in one coating according to the invention, in the water repellent Compound is a perfluoroalkyl-containing polymer.

Production of the carrier

Of the carrier is prepared analogously to Examples 1 and 2.

Plate precursor materials

The solutions listed in Table 2 are applied in a wet thickness of 20 microns on the carrier prepared as above and dried at 130 ° C for 1 minute. The materials are then exposed at different energy density values varying between 80 mJ / cm ² and 200 mJ / cm ² (exposure intensity on the image plane) using a Creo Trendsetter 3244 (830 nm).

After that the plates are replaced by 60 seconds Immersion in an aqueous-alkaline (marketed by Agfa) DP300 developer filled Development tank developed at a temperature of 25 ° C.

The Sensitivity to Infrared light of the various compositions corresponds to the minimum energy density adjustment needed to be used in areas those with an area coverage a 50s grid (@ 200 lpi) have been exposed, a 50% Reduction of the light absorption of the coating, wherein the measurement on the developed plate at the maximum wavelength of the Contrast dye takes place.

• * Alnovol SPN452 ist eine 40,5%ige Lösung in Dowanol PM (erhältlich durch Clariant),
• ** Triarylmethan-Farbstoff, erhältlich durch BASF,
• *** ein perfluoralkylhaltiges Polymer, erhältlich durch 3M/10 gew.-%ige Lösung in Methoxypropanol.

The results in Table 2 show that the coating containing a polysiloxane-containing infrared dye has a higher sensitivity than the comparative coating in which the corresponding infrared dye does not contain a polysiloxane group. Table 2 Ingredients (g) Example 3 (required) Example 4 (see) tetrahydrofuran 25.76 25.76 Alnovol SPN452 * 6.59 6.59 methoxypropanol 16,98 16,98 IR-2 0.1 - IR COMP1 - 0.1 Flexo blue 630 ** 0.03 0.03 Fluorad FC431 *** 0.14 0.14 2,3,4-trimethoxy 0.36 0.36 IR sensitivity (mJ / cm ² ) 100 > 200

• * Alnovol SPN452 is a 40.5% solution in Dowanol PM (available from Clariant),
• ** triarylmethane dye, available from BASF,
• *** A perfluoroalkyl-containing polymer, obtainable by 3M / 10% by weight solution in methoxypropanol.

Claims (13)

A heat-sensitive lithographic printing plate precursor comprising a support having a hydrophilic surface and a coating applied to the hydrophilic surface, the coating comprising in sequence a first layer containing an oleophilic, aqueous alkaline-soluble resin, and a second layer comprising capable of preventing penetration of the developer in unexposed areas, the second layer comprising a water-repellent compound selected from the group consisting of: a polymer having siloxane monomer units and / or perfluoroalkyl monomer units; and a block copolymer or graft copolymer with a poly (alkylene oxide) or oligo (alkylene oxide) and a polymer or oligomer with Siloxanmonomereinheiten and / or Perfluoralkylmonomereinheiten, and wherein the alkali solubility of the coating is enhanced by heating and the coating contains an infrared dye, characterized in that the infrared dye contains at least one polysiloxane group. A lithographic printing plate precursor according to claim 1, characterized in that the polysiloxane group covalently the infrared dye is bound. A lithographic printing plate precursor according to claim 1, characterized in that the infrared dye is charged and the polysiloxane group is embedded in a counterion. A lithographic printing plate precursor according to claim 1, characterized in that at least one polysiloxane group covalently bonded to the infrared dye and at least one Polysiloxane group is embedded in a counterion. Lithographic printing plate precursor according to one of previous claims, characterized in that the infrared dye is a squarylium dye, a croconate dye, a merocyanine dye, a cyanine dye, an indolizine dye, a pyrilium dye or a metal dithiolin dye is. Lithographic printing plate precursor according to any one of the preceding claims, characterized in that the water-repellent compound is used in an amount between 0.5 and 15 mg / m ² in the coating. Lithographic printing plate precursor according to one of previous claims, characterized in that the second layer of the coating essentially from the water repellent compound and the infrared dye is composed. Lithographic printing plate precursor according to one of the preceding claims, characterized in that the infrared dye corresponds to the formula:

in which: a and b independently of one another denote an integer between 0 and 4, -L ¹ - and -L ² - independently of one another denote a divalent linking group, -E ¹ and -E ² independently of one another represent a neutral, anionic or cationic end group the group consisting of alkyl, -OH, -H, -Cl, -Br, -F, -SiR ^a R ^b R ^c (neutral groups), -SO ₃ ^- , -SO ₄ ^- , -PO ₃ ^2- , - PO ₄ ^2- , -COO ^- (anionic groups) and - [NR ^d R ^e R ^f ] ⁺ (cationic group), wherein R ^a , R ^b and R ^c independently represent an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group and R ^d , R ^e and R ^f independently of one another denote a hydrogen atom or an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, -A ¹ - and -A ² - independently of one another - [Si (R ^g R ^h ) -O] _m -, -C _{v F 2 v} -, - [(CF ₂ ) ₂ -O] _w - or an optionally substituted alkyl group, alkenyl group, aryl group or aralkylg where R ^g and R ^h independently of one another are an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, - [O-Si (R ^a R ^b )] _q -E ¹ or - [O-Si (R ^a R ^b ) ] _q -E ² , where p ₁ and p _{2 are} 0 or 1, where t, u, q and m are 1 or an integer above 1, where v and w are 2 or an integer above 2, -Y ¹ - and -Y ² - are independently one or two unsubstituted, required to complete a 5-membered or 6-membered heterocyclic ring non-metal atoms, -Z ¹ - and -Z ² - independently represent a hydrogen atom or an alkyl group or together atoms necessary to complete a 5-membered or 6-membered ring, R ¹ and R ^{2 are} independently each represents a hydrogen atom, an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group or a halogen atom, -NO ₂ , -OR ⁱ , -CO-R ⁱ , -CO-OR ⁱ , -O-CO-R ⁱ , -CO-NR ⁱ R ^j , -NR ⁱ R ^j , -NR ⁱ -CO-R ^j , -NR ⁱ -CO-OR ^j , -NR ⁱ -CO-NR ^j R ^k , -SR ⁱ , -SO-R ⁱ , - SO ₂ -R ⁱ , -SO ₂ -OR ⁱ , -SO ₂ NR ⁱ R ^j , a perfluoroalkyl group or a polysiloxane group, each of said groups optionally comprising an end group E defined above as -E ¹ and -E ² and / / or two adjacent groups from the group consisting of R ¹ , R ² , -Y ¹ - and -Y ² - together form an optionally substituted 5-membered or 6-membered ring, wherein R ⁱ , R ^j and R ^k independently represent a hydrogen atom or an optionally substituted alkyl group, alkenyl group, aryl group or aralkyl group, R ^{3 represents} a substituent selected from the group consisting of a hydrogen atom, a halogen atom and an optionally substituted alkyl group, alkenyl group, aryl group, aralkyl group, perfluoroalkyl group, polysiloxane group, amino group, thioalkyl group, thioaryl group, aryloxy group, alkoxy group, barbituric acid group or thiobarbituric acid group and X represents one or more possible counterions having a total charge opposite to the total charge of the dye and X optionally contains a polysiloxane group, provided in that at least one of the following substituents contains a polysiloxane group: R ¹ , R ² , R ³ , -A ¹ -, -A ² - or X. Printing plate precursor according to Claim 8, characterized in that -Z ¹ and -Z ² together form - (CH ₂ ) ₂ - or - (CH ₂ ) ₃ -. Lithographic printing plate precursor according to claim 8 or 9, characterized in that the infrared dye corresponds to the following formulas:

in which: p ₁ , p ₂ , a, b, -L ¹ -, -L ² -, -E ¹ , -E ² , -A ¹ -, -A ² -, -Y ¹ -, -Y ² - , -Z ¹ , -Z ² , -R ³ and X have the meaning assigned to these symbols in claim 8, c and d independently of one another denote 0, 1 or 2 and R ⁶ to R ⁹ independently of one another as in claim 8 for R ¹ and R ^{2 are} defined, provided that at least one of the following substituents contains a polysiloxane group: R ³ , R ⁶ to R ⁹ , -A ¹ -, -A ² - or X. Lithographic printing plate precursor according to one of claims 8 to 10, characterized in that the infrared dye corresponds to the following formulas:

in which: p ₁ , p ₂ , a, b, -L ¹ -, -L ² -, -E ¹ , -E ² , -A ¹ -, -A ² -, R ¹ , R ² , R ³ and X assigned to these symbols in claim 8 R ⁴ and R ⁵ independently of one another are an optionally substituted alkyl group, alkenyl group, cycloalkyl group, aryl group or aralkyl group or a perfluoroalkyl group or polysiloxane group and each of these groups optionally contains an end group E defined in claim 8 as -E ¹ and -E ² , with the proviso that at least one of the following substituents contains a polysiloxane group: R ¹ , R ² , R ³ , R ⁴ , R ⁵ , -A ¹ -, -A ² - or X. Lithographic printing plate precursor according to one of claims 8 to 11, characterized in that the infrared dye corresponds to the following formulas:

in which R ^{10 is} - (CH ₂ ) _e -Si- [OSi (R ¹¹ R ¹² R ¹³ )] ₃ or - (CH ₂ ) _e -OCO- (CH ₂ ) _f - [Si (R ¹⁴ R ¹⁵ ) - O] _g - (CH ₂ ) _h -CH ₃ , R ⁴ and R ^{5 have} the meaning as defined in claim 11, R ¹¹ , R ¹² , R ¹³ , R ¹⁴ and R ¹⁵ independently of one another represent an optionally substituted alkyl group, Alkenyl group, aryl group or aralkyl group and e, f, g and h are 1 or an integer greater than 1. Lithographic printing plate precursor according to one of previous claims, characterized in that the polysiloxane group is a linear or branched structure.