Negative working, heat-sensitive lithographic printing plate precursor

1. A negative-working lithographic printing plate precursor comprising on a support having a hydrophilic surface or which is provided with a hydrophilic layer, a coating comprising:

(i) an infrared absorbing agent,

(ii) a first layer comprising hydrophobic thermoplastic polymer particles dispersed in a first hydrophobic binder,

(iii) and a second layer between said first layer and said hydrophilic support wherein said second layer comprises a second hydrophobic binder,

wherein said first hydrophobic binder is a phenolic resin and said second hydrophobic binder is a polymer comprising at least one sulphonamide group.

2. A negative-working lithographic printing plate precursor according to claim 1 wherein the second hydrophobic binder comprises a monomeric unit represented by the following formulae IIa or IIb:

wherein

R 7 , R 8 , R 9 and R 10 each independently represent hydrogen, a halogen, hydroxyl, an alkoxy or an optionally substituted alkyl or aryl group;

R 11 represents hydrogen, an optionally substituted alkyl, alkanoyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group, a group of the formula —C(═N)—NH—R 12 or an iso- or heterocyclic radical having 1 to 20 carbon atoms wherein a thiazolyl radical is excluded; and

R 12 represents hydrogen or an optionally substituted alkyl or aryl group.

3. A negative-working lithographic printing plate precursor according to claim 1 wherein the second hydrophobic binder comprises a monomeric unit represented by the following formula III:

wherein:

Ar represents an optionally substituted aromatic hydrocarbon ring;

n =0 or 1;

R 13 and R 14 each independently represent hydrogen or a hydrocarbon group having up to 12 carbon atoms;

k is an integer between 0 and 3;

X represents a single bond or a divalent linking group;

Y is a bivalent sulphonamide group represented by —NR j —SO 2 — or —SO 2 —NR k — wherein R j and R k each independently represent hydrogen, an optionally substituted alkyl, alkanoyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group, or a group of the formula —C(═N)—NH—R 15 , wherein R 15 represents hydrogen or an optionally substituted alkyl or aryl group; and

Z represents a terminal group.

4. A negative-working lithographic printing plate precursor according to claim 1 wherein the second hydrophobic binder comprises a polymer comprising a monomeric unit represented by the following formula IV:

wherein:

R 16 represents hydrogen or a hydrocarbon group having up to 12 carbon atoms;

X 1 represents a single bond or divalent linking group;

Y 1 is a bivalent sulphonamide group represented by —NR j —SO 2 — or —SO 2 —NR k — wherein R j and R k each independently represent hydrogen, an optionally substituted alkyl, alkanoyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group or a group of the formula —C(═N)—NH—R 15 , wherein R 15 represents hydrogen or an optionally substituted alkyl or aryl group; and

Z 1 represents a terminal group.

5. A negative-working lithographic printing plate precursor according to claim 1 wherein the phenolic resin is selected from a novolac resin, a resol resin or a polyvinyl phenol polymer.

6. A negative-working lithographic printing plate precursor according to claim 5 wherein the phenolic resin comprises a phenolic monomeric unit having a phenyl-group and a hydroxy- group, and wherein said phenyl-group or said hydroxy-group is chemically modified with an organic substituent.

7. A negative-working heat-sensitive lithographic printing plate precursor according to claim 6 wherein said organic substituent comprises the following formula I:

wherein n is 0, 1, 2 or 3,

wherein each R 1 is selected from hydrogen, an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group, —SO 2 —NH—R 2 , —NH—SO 2 —R 4 , —CO—NR 2 —R 3 , —NR 2 —CO—R 4 , —O—CO—R 4 , —CO—O—R 2 , —CO—R 2 , —SO 3 —R 2 , —SO 2 —R 2 , —SO—R 4 , —P(═O)(—O—R 2 )(—O—R 3 ),—NR 2 —R 3 , —O—R 2 , —S—R 2 , —CN, —NO 2 ,a halogen, —N-phthalimidyl, -M-N-phthalimidyl, or -M-R 2 , wherein M represents a divalent linking group containing 1 to 8 carbon atoms,

wherein R 2 , R 3 , R 5 and R 6 are independently selected from hydrogen or an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group,

wherein R 4 is selected from an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group,

or wherein at least two groups selected from each R 1 to R 4 together represent the necessary atoms to form a cyclic structure,

or wherein R 5 and R 6 together represent the necessary atoms to form a cyclic structure.

8. A negative-working working heat-sensitive lithographic printing plate precursor according to claim 6 wherein the phenyl-group of the phenolic monomeric unit of said phenolic resin is substituted with a group having the structure —N═N-Q, wherein the —N═N— group is covalently bound to a carbon atom of the phenyl group and wherein Q has the structure of formula I

wherein n is 0, 1, 2 or 3,

wherein each R 1 is selected from hydrogen, an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group, —SO 2 —NH—R 2 , —NH—SO 2 —R 4 , —CO—NR 2 —R 3 , —NR 2 —CO—R 4 , —O—CO—R 4 , —CO—O—R 2 , —CO—R 2 , —SO 3 —R 2 , —SO 2 —R 2 ,—SO—R 4 ,—P(═O)(—O—R 2 )(—O—R 3 ), —NR 2 —R 3 , —O—R 2 , —S—R 2 , —CN, —NO 2 , a halogen, —N-phthalimidyl, -M-N-phthalimidyl, or -M-R 2 , wherein M represents a divalent linking group containing 1 to 8 carbon atoms,

wherein R 2 , R 3 , R 5 and R 6 are independently selected from hydrogen or an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group,

wherein R 4 is selected from an optionally substituted alkyl, alkenyl, alkynyl, cycloalkyl, heterocyclic, aryl, heteroaryl, aralkyl or heteroaralkyl group,

or wherein at least two groups selected from each R 1 to R 4 together represent the necessary atoms to form a cyclic structure,

or wherein R 5 and R 6 together represent the necessary atoms to form a cyclic structure.

9. A negative-working lithographic printing plate precursor according to claim 1 wherein the first layer has a thickness of at least 0.3 micrometer.

10. A negative-working lithographic printing plate precursor according to claim 1 wherein the hydrophobic thermoplastic polymer particles comprise polyethylene, poly(vinyl)chloride, polymethyl(meth)acrylate, polyethyl (meth)acrylate, poyvinylidene chloride, poly(meth)acrylonitrile, polyvinylcarbazole, polystyrene or copolymers thereof.

11. A method for preparing a negative-working lithographic printing plate comprising the steps of:

(i) providing a negative working printing plate precursor according to claim 1 ,

(ii) imagewise exposing the coating to heat and/or infrared light, thereby reducing the capacity of said coating of being penetrated and/or solubilized by an aqueous alkaline solution,

(iii) developing the imagewise exposed precursor with said aqueous alkaline solution thereby dissolving the non-exposed areas.