Method for preparing lithographic printing plate precursors

1. A method of preparing a lithographic printing plate in which no pre-heat step is utilized comprising the steps of:

providing a lithographic printing plate precursor comprising a support and a photopolymerizable image-recording layer, the image-recording layer comprising a monomer and a binder;

image-wise exposing the precursor in an exposure unit; and

off press developing the exposed precursor with an aqueous solution in a processing unit, wherein the ratio of the total amount of monomer to the total amount of binder is at least 1 and the time lapse between exposing an image-area of the precursor and contacting the image-area with the aqueous solution is at least 2.5 minutes.

2. The method according to claim 1 , wherein the time lapse is at least 5 minutes.

3. The method according to claim 1 , wherein the exposed precursor is automatically transported from the exposure unit towards the processing unit by transferring means.

4. The method according to claim 2 , wherein the exposed precursor is automatically transported from the exposure unit towards the processing unit by transferring means.

5. The method according to claim 3 , wherein the transferring means comprise a stacking unit for temporary storage of the exposed precursor.

6. The method according to claim 4 , wherein the transferring means comprise a stacking unit for temporary storage of the exposed precursor.

7. The method according to claim 1 , wherein the ratio of the total amount of monomer to the total amount of binder is at least 1.5.

8. The method according to claim 2 , wherein the ratio of the total amount of monomer to the total amount of binder is at least 1.5.

9. The method according to claim 1 , wherein the aqueous solution has a pH between 2 and 10.

10. The method according to claim 1 , wherein the image-recording layer comprises an adhesion promoter containing an ethylenically-unsaturated group and a group capable of interacting with the support.

11. The method according to claim 2 , wherein the image-recording layer comprises an adhesion promoter containing an ethylenically-unsaturated group and a group capable of interacting with the support.

12. The method according to claim 8 , wherein the image-recording layer comprises an adhesion promoter containing an ethylenically-unsaturated group and a group capable of interacting with the support.

13. The method according to claim 1 , wherein the binder has an acid value of less than 0.3 meq/g.

14. The method according to claim 13 , wherein the binder is a partially hydrolyzed polyvinylalcohol with a hydrolysis degree of between 10 and 65 mol %.

15. The method according to claim 1 , wherein the image-recording layer comprises a hydrophilic polymer having at least 1 mol % of a first monomeric unit having a phosphate group, a phosphonate group, a carboxylic acid group, a sulphonic acid group, a phenolic group, a trialkoxysilane group, an ammonium group or a phosphonium group and at least 30 mol % of a second monomeric unit having a hydrophilic group.

16. The method according to claim 8 , wherein the image-recording layer comprises a hydrophilic polymer having at least 1 mol % of a first monomeric unit having a phosphate group, a phosphonate group, a carboxylic acid group, a sulphonic acid group, a phenolic group, a trialkoxysilane group, an ammonium group or a phosphonium group and at least 30 mol % of a second monomeric unit having a hydrophilic group.

17. The method according to claim 1 , wherein the image-recording layer comprises a pigment which does not contain a dispersant or which is dispersed with a dispersant which is free from a —COOH, —PO 3 H 2 and a —OPO 3 H 2 group.

18. The method according to claim 8 , wherein the image-recording layer comprises a pigment which does not contain a dispersant or which is dispersed with a dispersant which is free from a —COOH, —PO 3 H 2 and a —OPO 3 H 2 group.

19. The method according to claim 16 , wherein the image-recording layer comprises a pigment which does not contain a dispersant or which is dispersed with a dispersant which is free from a —COOH, —PO 3 H 2 and a —OPO 3 H 2 group.

20. The method according to claim 18 , wherein the image-recording layer comprises a pigment which does not contain a dispersant or which is dispersed with a dispersant which is free from a —COOH, —PO 3 H 2 and a —OPO 3 H 2 group.

21. The method according to claim 1 , wherein the image-recording layer comprises a hinder with a glass transition temperature Tg of less than 80° C.