Photosensitive composition, planographic printing plate and processing method of planograhic printing plate

1. A photosensitive composition comprising:

(a) a polymerizable compound having an ethylenically unsaturated group;

(b) a metallic arene compound; and

(c) an acid generating agent,

wherein, the polymerizable compound is a multifunctional acrylate compound containing an amide bond and a secondary or tertiary amine group in the molecule,

the acid generating agent is a compound containing a trihalomethyl group, dihalomethyl group or dihalomethylene group, and

the metallic arene compound is represented by Formula (5):

wherein X 1 is a group containing at least one benzene ring; Y 1 is a basic ionic compound; and M is a metal.

2. The photosensitive composition according to claim 1 , wherein the acid generating agent is a compound represented by Formulas (1) or (2):

CR 2 x H 3-x —(C═O)—R 1   Formula (1)

wherein x is an integer of 2 or 3, R 1 is an aryl group, an acyl group or an organic group having a heterocyclic group, and R 2 is a chlorine atom or a bromine atom,

CR 2 x H 3-x —R 3   Formula (2)

wherein x is an integer of 2 or 3, R 3 is an aryl group, an acyl group or an organic heterocyclic group other than a triazine group, and R 2 is a chlorine atom or a bromine atom.

3. The photosensitive composition according to claim 2 , wherein the acid generating agent contains an oxadiazole group.

4. The photosensitive composition according to claim 2 , wherein the acid generating agent is a compound represented by Formulas (3) or (4),

R 4 —C(Y) 2 —(C═O)—R 5   Formula (3)

wherein R 4 is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group or a cyano group, R 5 is an monovalent substituent group, provided that R 4 and R 5 may combine to form a ring, and Y is a halogen atom,

C(Y) 3 —(C═O)—X—R 6   Formula (4)

wherein R 6 is a monovalent substituent group, X is O or —NR 7 —, R 7 is a hydrogen atom or an alkyl, group, provided that R 6 and R 7 may combine to form a ring, and Y is a halogen atom.

5. The photosensitive composition according to claim 1 , wherein the acid generating agent contains an oxadiazole group.

6. The photosensitive composition according to claim 1 , wherein the acid generating agent is a compound represented by Formulas (3) or (4):

R 4 —C(Y) 2 —(C═O)—R 5   Formula (3)

wherein R 4 is a hydrogen atom, a halogen atom, an alkyl group, an aryl group, an acyl group, an alkylsulfonyl group, an arylsulfonyl group or a cyano group, R 5 is an monovalent substituent group, provided that R 4 and R 5 may combine to form a ring, and Y is a halogen atom,

C(Y) 3 —(C═O)—X—R 6   Formula (4)

wherein R 6 is a monovalent substituent group, X is O or —NR 7 —, R 7 is a hydrogen atom or an alkyl group, provided that R 6 and R 7 may combine to form a ring, and Y is a halogen atom.

7. The photosensitive composition according to claim 1 , wherein the halogen atom of the acid generating agent is a chlorine atom or a bromine atom.

8. The photosensitive composition according to claim 1 , wherein 10 to 90 weight % of the polymerizable compound has a weight average molecular weight of 15,000 to 500,000 and an acid value of 30 to 200 mg/KOH.

9. The photo polymerizable compound according to claim 8 , wherein a ratio of units having a reactive group is 5 to 50 mol % based on the total mole of the polymerizable compound.

10. The photosensitive composition according to claim 1 , wherein the photosensitive composition further contains at least one dye selected from the group consisting of a coumarin, ketocoumarin, oxonol, barbituric acid, pyrromethane borate, diphenylmethane, xanthene dye, coumarin derivatives, and thiobarbituric acid skeleton.

11. A planographic printing plate comprising a support having thereon the following layers in the order:

(a) a layer containing the photosensitive composition described in claim 1 ; and

(b) an oxygen shielding layer;

wherein the support is a metallic support and a surface of the support is electrically roughened in an acid medium, and then subjected to an anodization treatment to provide a surface Ra of 0.2 to 0.7 μm.

12. The planographic printing plate according to claim 11 , wherein the surface Ra of the support is 0.5 to 0.7 μm.

13. The planographic printing plate according to claim 12 , wherein the surface of the support is further treated with polyvinylphosphonic acid to provide hydrophilicity.

14. A method for processing the planographic printing plate described in claim 11 comprising the steps of:

(a) exposing the planographic printing plate to a laser; and

(b) forming an image with an alkaline development processing,

wherein the processing is conducted with a developing solution of pH of 10.0 to 12.5.

15. The processing method according to claim 14 , wherein the alkaline developing solution contains an inorganic alkaline agent and a nonionic surface active agent having a polyoxyalkylene ether group, and a specific electric conductivity of the alkaline developing solution is 3 to 30 mS/cm.

16. The processing method according to claim 14 , wherein the alkaline developing solution contains an inorganic alkaline agent and an anionic surface active agent having a polyoxyalkylene ether group, and a specific electric conductivity of the alkaline developing solution is 3 to 30 mS/cm.