UV-absorbing ink composition for ink-jet printing

1. An ink composition for ink-jet printing comprising a UV-absorbing compound according to formula (I):

wherein:

R 1 is selected from the group consisting of hydrogen, a substituted or unsubstituted, saturated or unsaturated aliphatic group, which may be interrupted by at least one heteroatom and may be cyclic, and a substituted or unsubstituted aromatic or heteroaromatic group;

R 2 is selected from the group consisting of hydrogen, a substituted or unsubstituted, saturated or unsaturated aliphatic group, which may be interrupted by at least one heteroatom, a substituted or unsubstituted aromatic or heteroaromatic group, —COR 4 and —NR 5 R 6 ;

R 3 is selected from the group consisting of hydrogen, a substituted or unsubstituted, saturated or unsaturated aliphatic group, which may be interrupted by at least one heteroatom, a substituted or unsubstituted aromatic or heteroaromatic group, and E″;

E, E′ and E″ independently represent an electron withdrawing group;

R 4 is selected from the group consisting of a hydrogen, a substituted or unsubstituted, saturated or unsaturated aliphatic group, which may be interrupted by at least one heteroatom, a substituted or unsubstituted aromatic or heteroaromatic group, —OR 7 and —NR 8 R 9

M represents a hydrogen or a counter-ion

R 5 and R 6 are independently selected from the group consisting of hydrogen, a substituted or unsubstituted, saturated or unsaturated aliphatic group, which may be interrupted by at least one heteroatom, a substituted or unsubstituted aromatic or heteroaromatic group, an acyl group, an oxalyl group, a sulphonyl group and a phosphoryl group;

R 7 to R 9 are independently selected from the group consisting of hydrogen, a substitututed or unsubstituted, saturated or unsaturated aliphatic group, which may be interrupted by at least one heteroatom and a substituted or unsubstituted aromatic or heteroaromatic group;

any of the possible combinations of R 2 , R 3 , E and E′ may combine to form a ring;

R 5 and R 6 may represent the necessary atoms to form a 5- to 8-membered ring; and

R 8 and R 9 may represent the necessary atoms to form a 5- to 8-membered ring.

2. An ink composition according to claim 1 wherein said R 1 group is an aromatic group substituted with a water-solubilizing group.

3. An ink composition according to claim 1 wherein said electron-withdrawing group is a nitrile group.

4. An ink composition according to claim 2 wherein said electron-withdrawing group is a nitrile group.

5. An ink composition according to claim 1 wherein said UV-absorbing compound has the formula:

6. A method for preparing a printing element comprising the following steps

(1) providing an ink-jet recording material on a transparent support,

(2) information-wise jetting droplets of a UV-absorbing ink composition as claimed in claim 1 onto the front surface of the ink-jet recording material by means of an ink-jet printer thus forming a printed image,

(3) overall exposing to UV light a UV-sensitive printing element precursor through a mask consisting of the printed image formed by steps 1 and 2,

(4) developing the exposed UV-sensitive printing element precursor into a printing element.

7. A method according to claim 6 wherein said printing element is a lithographic printing plate.

8. A method according to claim 6 wherein said printing element is a flexographic printing plate.

9. A method according to claim 6 wherein said printing element is a silk screen printing element.

10. A method according to claim 6 wherein said printing element precursor is a printed circuit board precursor.

11. A mask in which the UV-absorbing areas contain a compound according to formula (I) as defined in claim 1 .