Lithographic printing plate precursor comprising bi-functional compounds

1. A heat-sensitive lithographic printing plate precursor comprising on a grained and anodized aluminum support a compound which is capable of converting from a hydrophobic state or vice versa to a hydrophilic state upon exposure to heat and/or in the presence of an acid or a base, and is represented by the following formula:

A-(L) n -B

wherein

L represents a linking group,

n represents 0 or 1;

B represents a thermo-labile group;

and A is selected from the group consisting of a halosilanyl group, an alkoxysilanyl group, a phosphonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, a salicylic acid group or a salt thereof, a boronic acid group or an ester or a salt thereof, an optionally substituted di- or tri-hydroxyaryl group, an optionally substituted salicaldoxime group, an optionally substituted salicaldimine group, an optionally substituted hydroxyheteroaryl group, an amidine group, a 1,3-dicarbonyl group or a group represented by the formula (i)

wherein Q and Z independently represent the necessary atoms to form an optionally substituted five or six membered aromatic or heteroaromatic ring;

and group B comprises an optionally substituted alkyl group, an alkyl carboxylate group, an alkoxyalkyl carboxylate group, a benzyl carboxylate group, an oxime carboxylate group, an alkyl carbonate group, an alkoxyalkyl carbonate group, a benzyl carbonate group, an oxime carbonate group, an alkyl carbamate group, an alkoxyalkyl carbamate group, a benzyl carbamate group an oxime carbamate group, —PO—(OR a ) 2 , —SO 2 —O—R b , —OPO—(OR c ) 2 , —OSO 2 —O—R d , —SO 2 —SO 2 —R e , —SO 2 —NR f —SO 2 —R g wherein R a to R g each represent an optionally substituted alkyl or aryl group, or R a to R d represent a cyclic imide group or R f represents —SO 2 —R h wherein R h represents an optionally substituted alkyl or aryl group.

2. A printing plate precursor according to claim 1 further comprising an infrared absorbing agent.

3. A printing plate precursor according to claim 2 wherein the infrared absorbing agent provides a visible image after image-wise exposure.

4. A method for making a lithographic printing plate comprising the steps of:

(i) providing a printing plate precursor according to claim 1 ;

(ii) image-wise exposing said precursor to heat and/or infrared light whereby the surface of the precursor converts from a hydrophobic state or vice versa to a hydrophilic state at exposed areas.

5. A method of lithographic printing comprising the steps of:

providing a printing plate precursor according to claim 1 ;

(ii) image-wise exposing said precursor to heat and/or infrared light whereby the surface of the precursor converts from a hydrophobic state or vice versa to a hydrophilic state at exposed areas;

(iii) mounting the exposed precursor on a printing press; and

(iv) applying ink and/or dampening liquid onto the exposed precursor.

6. A printing plate precursor according to claim 1 , wherein group A of said compound represents a phosphonic acid group or a salt thereof, a phosphoric acid group or a salt thereof, an optionally substituted di- or tri-hydroxyaryl group, an alkoxysilanyl group, or a salicylic acid group and group B of said compound represents an optionally substituted alkyl group, an alkyl carboxylate group, an alkoxyalkyl carboxylate group or a benzyl carboxylate group.

7. A printing plate precursor according to claim 1 , wherein L is selected from the group consisting of an optionally substituted alkylene group, an optionally substituted arylene, an optionally substituted heterearylene, —SO—, —SO 2 —, —CH═N—, —NH—NH—, —O—(CH 2 ) k —, —(CH 2 ) k —O—, —(CH 2 ) k —O—CO—(CH 2 ) l , —(CH 2 ) k —COO—(CH 2 ) l —, —(CH 2 ) k —NH—, —NH—(CH 2 ) k —, —(CH 2 ) k —CONH—, —(CH 2 ) k —NHCO—, —(CH 2 ) k —CONH—SO 2 —, —NH—(CH 2 ) k —O—(CH 2 ) l —, —CO—(CH 2 ) k —, —(CH 2 ) k —CO—, —NH—CO—O—, —O—CO—NH—, —NH—CO—(CH 2 ) k —, —NH—CO—NH—, —NH—CS—NH—, and any combination thereof; and wherein k and l independently represent 0 or an integer equal to or greater than 1.