3-ketocoumarines for LED photocuring

1. A process for LED photocuring photopolymerizable compositions comprising:

I) preparing a photopolymerizable composition comprising:

a) from about 50 to about 99.9% by weight of at least one ethylenically unsaturated compound; and

b) from about 0.1 to about 35% by weight by weight of at least one 3-ketocoumarine having a general formula I:

wherein:

R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group;

Cou is a coumarine group of formula:

wherein:

at least one of R 2 R 3 , R 4 and R 5 is —S—R 7 ,

wherein R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, —N(C 1 -C 6 alkyl) 2 , piperidino, morpholino, piperazine, —OH, —O(C 1 -C 12 alkyi), —COOH, and

R 6 is hydrogen, a hydroxyl group or an alkyl group having from 1 to 4 carbon atoms;

and

II) photopolymerizing the photopolymerizable composition so obtained with a LED light source emitting at wavelengths ranging from 365 nm to 420 nm.

2. The process for photocuring photopolymerizable compositions of claim 1 , wherein the photopolymerizable composition comprises:

a) from about 70 to about 98.9% by weight of at least one ethylenically unsaturated compound;

b) from about 0.1 to about 20% by weight of at least one 3-ketocoumarine of formula I.

3. The process for photocuring photopolymerizable compositions according to claim 1 , wherein the photopolymerizable composition further comprises from about 0.2 to about 15% by weight of at least one co-initiator and/or from about 0.5 to about 15% by weight of at least one additional photoinitiator.

4. The process for photocuring photopolymerizable compositions of claim 3 , wherein the photopolymerizable composition comprises from about 70 to about 98.9% by weight of at least one photopolymerizable compound, from about 0.1 to about 10% by weight of at least one 3-ketocoumarine of formula I, from about 1 to about 15% by weight at least one sensitizable photoinitiator and, optionally, from about 0.2 to about 8% by weight of a co-initiator.

5. The process for photocuring photopolymerizable compositions of claim 1 , wherein the photopolymerizable composition further comprises: c) from 0.01 to 30% by weight of colorants.

6. The process for photocuring photopolymerizable compositions of claim 5 , wherein the photopolymerizable composition comprises:

a) from about 70 to about 98.9% by weight of at least one ethylenically unsaturated compound;

b) from about 0.1 to about 20% by weight of at least one 3-ketocoumarine of formula I.

7. The process for photocuring photopolymerizable compositions according to claim 5 , wherein the photopolymerizable composition further comprises from about 0.2 to about 15% by weight of at least one co-initiator and/or from about 0.5 to about 15% by weight of at least one additional photoinitiator.

8. The process for photocuring photopolymerizable compositions of claim 7 , wherein the photopolymerizable composition comprises from about 70 to about 98.9% by weight of at least one photopolymerizable compound, from about 0.1 to about 10% by weight of at least one 3-ketocoumarine of formula I, from about 1 to about 15% by weight at least one sensitizable photoinitiator and, optionally, from about 0.2 to about 8% by weight of a co-initiator.

9. The process for photocuring photopolymerizable compositions of claim 5 , wherein the colorants are colorants for ink-jet printing.

10. A composition comprising 3-ketocoumarines having a general formula I:

wherein:

R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group;

Cou is a coumarine group of formula:

wherein

at least one of R 2 R 3 , R 4 and R 5 is —S—R 7 ,

wherein R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, —N(C 1 -C 6 alkyl) 2 , piperidino, morpholino, piperazine, —OH, —O(C 1 -C 12 alkyi), —COOH, and

R 6 is hydrogen, a hydroxyl group or an alkyl group having from 1 to 4 carbon atoms.

11. The composition of claim 10 wherein R 7 is an alkyl group having from 1 to 6 carbon atoms.

12. A composition comprising 3-ketocoumarines having a general formula I:

wherein:

R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group; and

Cou is a coumarine group of formula:

wherein

at least one of R 2 R 3 , R 4 and R 5 is an alkoxy group having from 1 to 6 carbon atoms and R 6 is hydrogen, a hydroxyl group or an alkyl group having from 1 to 4 carbon atoms;

or Cou is a substituted or unsubstituted naphtho-coumarine having a general formula selected from the group consisting of:

13. A process for LED photocuring photopolymerizable compositions comprising:

I) preparing a photopolymerizable composition comprising:

a) from about 50 to about 99.9% by weight of at least one ethylenically unsaturated compound; and

b) from about 0.1 to about 35% by weight by weight of at least one 3-ketocoumarine having a general formula I:

wherein:

R 1 is a substituted or unsubstituted C 2 -C 12 alkyl group;

Cou is a coumarine group of formula:

wherein:

R 2 , R 3 , R 4 and R 5 are, independently of one another, hydrogen; or —S—R 7 , wherein R 7 is hydrogen, C 1 -C 12 alkyl, C 3 -C 12 alkenyl, substituted or unsubstituted phenyl, aryl or heteroaryl, C 5 -C 6 cycloalkyl, C 1 -C 12 alkyl which is substituted with SH, —N(C 1 -C 6 alkyl) piperidino, morpholino, piperazino, —OH, —O(C 1 -C 12 alkyl), —COOH;

or C 1 -C 12 alkoxy;

R 6 is hydrogen, a hydroxyl group, an alkyl group having from 1 to 4 carbon atoms;

or Cou is a substituted or unsubstituted naphtho-coumarine group having a general formula selected from the group consisting of:

wherein at least one of R 2 , R 3 , R 4 and R 5 is different from H and that, when Cou is (a) and at least one of R 2 , R 3 , R 4 and R 5 is C 1 -C 12 alkoxy or when Cou is (b), (c) or (d), R 1 is a substituted or an unsubstituted C 1 -C 12 alkyl group; and

II) photopolymerizing the photopolymerizable composition so obtained with a LED light source emitting at wavelengths ranging from 365 nm to 420 nm; and

wherein:

in the 3-ketocoumarine of formula I, Cou is a coumarine group of formula (a) and at least one of R 2 R 3 , R 4 and R 5 is —S—R 7 and R 7 is an alkyl group having from 1 to 6 carbon atoms;

in the 3-ketocoumarine of formula I, Cou is a coumarine group of formula (a) in which R 6 is hydrogen, at least two of R 2 R 3 , R 4 and R 5 are a C 1- C 6 alkoxy group and R 1 is a substituted or unsubstituted C 1 -C 12 alkyl group; or

in the 3-ketocoumarine of formula I, Cou is an unsubstituted naphtho-coumarine group of formula (b), (c) or (d).

14. The process for photocuring photopolymerizable compositions of claim 13 , wherein the photopolymerizable composition further comprises: c) from 0.01 to 30% by weight of colorants.

15. The process for photocuring photopolymerizable compositions of claim 14 , wherein the photopolymerizable composition comprises:

a) from about 70 to about 98.9% by weight of at least one ethylenically unsaturated compound;

b) from about 0.1 to about 20% by weight of at least one 3-ketocoumarine of formula I.