Negative working, heat-sensitive, lithographic printing plate precursor

1. A heat-sensitive lithographic printing plate precursor based on heat-induced latex coalescence comprising:

a grained and anodized aluminum support; and

a heat-sensitive coating arranged on the support, the heat-sensitive coating including heat-induced coalescing hydrophobic thermoplastic polymer particles, a hydrophilic binder, and an organic compound including at least one phosphonic acid group or at least one phosphoric acid group or a salt thereof; wherein

the organic compound is represented by the following formula:

or a salt thereof; and wherein:

n represents 0 or 1;

R 1 and R 2 independently represent hydrogen, a straight, branched, cyclic, or heterocyclic alkyl group having up to 8 carbon atoms, a halogen, a hydroxyl group, or an aryl or heteroaryl group; and

R 3 represents a straight, branched, cyclic, or heterocyclic alkyl group having up to 8 carbon atoms, a halogen, a hydroxyl group, an aryl or heteroaryl group, a carboxyl group, a phosphonic acid group, a phosphoric acid group, a sulphuric acid group, or a sulfonic acid group.

2. The printing plate precursor according to claim 1 , wherein the hydrophobic thermoplastic particles are stabilized with an anionic dispersion aid.

3. The printing plate precursor according to claim 2 , wherein the anionic dispersion aid is an organic compound including a carboxylate group.

4. The printing plate precursor according to claim 1 , wherein n is 0.

5. The printing plate precursor according to claim 1 , wherein the organic compound is present in the heat-sensitive coating in an amount ranging from 10 mg/m 2 to 160 mg/m 2 .

6. The printing plate precursor according to claim 1 , wherein the hydrophobic thermoplastic polymer particles have an average particle size in the range from 40 nm to 70 nm.

7. The printing plate precursor according to claim 1 , wherein the amount of the hydrophobic thermoplastic polymer particles in the heat-sensitive coating is at least 70% by weight.

8. The printing plate precursor according to claim 1 , wherein the hydrophobic thermoplastic polymer particles include at least 5% by weight of nitrogen containing units.

9. A method for making a heat-sensitive lithographic printing plate precursor comprising the step of:

providing the grained and anodized aluminum support and the heat-sensitive coating including the hydrophobic thermoplastic polymer particles, hydrophilic binder, and organic compound as defined in claim 1 ; and

coating the heat-sensitive coating onto the support.

10. A method according to claim 9 , wherein the hydrophobic thermoplastic polymer particles have an average particle size in the range from 40 nm to 70 nm.

11. A method according to claim 9 , wherein the amount of the hydrophobic thermoplastic polymer particles in the heat-sensitive coating is at least 70% by weight.

12. A method according to claim 9 , wherein the hydrophobic thermoplastic polymer particles include at least 5% by weight of nitrogen containing units.

13. A method for making a heat-sensitive lithographic printing plate comprising the steps of:

providing the printing plate precursor according to claim 1 ;

exposing the printing plate precursor to heat to coalesce the hydrophobic thermoplastic polymer particles; and

developing the exposed precursor by removing unexposed areas in a processing liquid.

14. A method for making a heat-sensitive lithographic printing plate comprising the steps of:

providing the printing plate precursor according to claim 1 ;

exposing the printing plate precursor to heat to coalesce the hydrophobic thermoplastic polymer particles; and

mounting the precursor on a printing press and developing it by supplying ink and/or fountain solution to the precursor.

15. A heat-sensitive lithographic printing plate precursor based on heat-induced latex coalescence comprising:

a grained and anodized aluminum support; and

a heat-sensitive coating arranged on the support, the heat-sensitive coating including heat-induced coalescing hydrophobic thermoplastic polymer particles, a hydrophilic binder, and an organic compound including at least one phosphonic acid group or at least one phosphoric acid group or a salt thereof; wherein

the organic compound is represented by the following formula:

or a salt thereof; and wherein:

R 4 and R 5 independently represent hydrogen, an optionally substituted straight, branched, cyclic, or heterocyclic alkyl group having up to 8 carbon atoms, a halogen, a hydroxyl group, or an optionally substituted aryl or heteroaryl group.

16. A heat-sensitive lithographic printing plate precursor based on heat-induced latex coalescence comprising:

a grained and anodized aluminum support; and

a heat-sensitive coating arranged on the support, the heat-sensitive coating including heat-induced coalescing hydrophobic thermoplastic polymer particles, a hydrophilic binder, and an organic compound including at least one phosphonic acid group or at least one phosphoric acid group or a salt thereof; wherein

the organic compound is represented by the following formula:

or a salt thereof; and wherein:

R 6 independently represents hydrogen, an optionally substituted straight, branched, cyclic, or heterocyclic alkyl group having up to 8 carbon atoms, or an optionally substituted aryl or heteroaryl group.