Solvent resistant polymers with improved bakeablity features

1. A copolymer for use in coating compositions for printing plate precursors, the copolymer comprising units A, B, and a unit C comprising a cyclic terminal urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and has the formula is represented by

wherein R 1 is selected such that the homopolymer of A is alkali-soluble, unit B is present in an amount of about 20 to about 70 mol % and has the following formula is represented by

wherein R 2 is selected such that the homopolymer of B has a glass transition temperature greater than 100° C., preferably a glass transition temperature in the range from about 100 to about 380° C., and the unit C comprising a cyclic terminal urea group is present in an amount of about 10 to about 50 mol % and has the formula is represented by

wherein X is a spacer group which is preferably selected from the group consisting of (a) a —(CR 2 ) m — chain, (b) a —[CH 2 —CH 2 —O] m — chain; and (c) a —[Si(R 2 )—O] m — unit, wherein m is an integer between 2 and 12, the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer between 1 and 5; and

Y is a group selected from the group consisting of:

wherein each R in units A, B, and C, the —(CR 2 ) m — chain, the —[Si(R 2 )—O] m — unit, and group Y represents a bond between the cyclic urea and the spacer group X, or is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, and or halogen.

2. A The copolymer according to claim 1 , wherein R 1 in unit A of the copolymer is selected from the group consisting of hydrogen, aryl and (C 1 -C 12 )alkyl having at least one carboxy group.

3. A copolymer according to claim 1 , wherein the copolymer has a weight-average molecular weight in the range of 500 to 1,000,000.

4. A The copolymer according to claim 1 , wherein the copolymer further comprises unit D, wherein unit D is present in an amount of about 10 to about 50 mol % and has the formula is represented by

wherein R 3 is selected such that the homopolymer of D is miscible with water in any ratio water-soluble, and R is independently selected from hydrogen, aryl, (C 1 -C 12 )alkyl, and halogen, with the proviso that unit D is different from unit A.

5. A The copolymer according to claim 3 , wherein R 3 in unit D of the copolymer is selected from the group consisting of hydrogen, a (C 1 -C 12 ) alkyl group, a (C 3 -C 8 ) cycloalkyl group, an aryl group, an —NH(CH 2 ) n O-alkyl group wherein n is an integer between 1 and 20 , a (C 1 - C 12 ) alkoxy group, and an —NHR 4 group, and a (C 1 -C 12 )alkoxy group, wherein n is an integer between 1 and 20 and group wherein R 4 is hydrogen, (C 1 -C 12 ) alkyl or aryl.

6. A The copolymer according to claim 4 , wherein the C 1 -C 12 alkyl group R 3 in unit D of the copolymer comprises at least one hydroxy group and at least one substituent selected from the group consisting of halogen and —NO 2 .

7. A copolymer according to claim 5 , wherein the C 3 -C 8 alkyl group comprises at least one hydroxy group and at least one substituent selected from the group consisting of halogen and —NO 2 .

8. A copolymer according to claim 5 , wherein the aryl group comprises at least one hydroxy group and at least one substituent selected from the group consisting of halogen, (C 1 -C 12 )alkyl and —NO 2 .

9. A radiation-sensitive composition comprising

(a) at least one novolak;

(b) at least one naphthoquinone diazide derivative; and

(c) a copolymer comprising units A, B, and a unit C comprising a cyclic terminal urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and has the formula is represented by

 wherein R 1 is selected such that the homopolymer of A is alkali-soluble, unit B is present in an amount of about 20 to about 70 mol % and has the following formula is represented by

 wherein R 2 is selected such that the homopolymer of B has a glass transition temperature greater than 100° C., preferably a glass transition temperature in the range from about 100 to about 380° C., and the unit C comprising a cyclic terminal urea group is present in an amount of about 10 to about 50 mol % and has the formula is represented by

 wherein X is a spacer group which is preferably selected from the group consisting of (a) a —(CR 2 ) m — chain, (b) a —[CH 2 —CH 2 —O] m — chain; and (c) a —[Si(R 2 )—O] m — unit, wherein m is an integer between 2 and 12, the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer between 1 and 5; and

 Y is a group selected from the group consisting of:

 wherein each R in units A, B, and C, the —(CR 2 ) m — chain, the —[Si(R 2 )—O] m — unit, and group Y represents a bond between the cyclic urea and the spacer group X, or is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, and or halogen.

10. A The radiation-sensitive composition according to claim 6 , wherein the weight ratio of novolak to copolymer is in the range of 90:10 to 10:90.

11. A The radiation-sensitive composition according to claim 7 , wherein the copolymer is present in an amount of at least 60% by weight based on the total amount of copolymer and novolak.

12. A radiation-sensitive composition according to claim 9 , wherein the copolymer acts as a binder and the composition does not comprise an additional binder.

13. A radiation-sensitive composition according to claim 9 , wherein the composition additionally comprises at least one further component selected from radiation-sensitive acid donors, dyes or pigments for increasing the contrast of the image, exposure indicators and plasticizers.

14. A The radiation-sensitive composition according to claim 8 , wherein R 1 in unit A of the copolymer is selected from the group consisting of hydrogen, aryl and (C 1 -C 12 ) alkyl having at least one carboxy group.

15. A The radiation-sensitive composition according to claim 9 , wherein R 2 in unit B of the copolymer is selected from the group consisting of hydrogen, aryl, (C 1 -C 12 ) alkyl, and (C 3 -C 8 ) cycloalkyl.

16. A radiation-sensitive composition according to claim 9 , wherein the copolymer has a weight-average molecular weight in the range of 500 to 1,000,000.

17. A The radiation-sensitive composition according to claim 9 , wherein the novolak and the naphthoquinone diazide derivative are not used as separate components but are used in the form of a naphthoquinone diazide derivative reacted with a novolak.

18. A The radiation-sensitive composition according to claim 9 , wherein the copolymer further comprises unit D, wherein unit D is present in an amount of about 10 to about 50 mol % and has the formula is represented by

wherein R 3 is selected such that the homopolymer of D is water-soluble and R is independently selected from hydrogen, aryl, (C 1-C12 ) alkyl, and halogen , with the proviso that unit D is different from unit A.

19. A The radiation-sensitive composition according to claim 18 , wherein R 3 in unit D of the copolymer is selected from the group consisting of hydrogen, a (C 1 -C 12 )alkyl group, a (C 3 -C 8 ) cycloalkyl group, an aryl group, an —NH(CH 2 ) n O—alkyl group wherein n is an integer between 1 and 20 , a (C 1 - C 12 ) alkoxy group, and an —NHR 4 group, and a (C 1 -C 12 )alkoxy group, wherein n is an integer between 1 and 20 and group wherein R 4 is hydrogen, C 1 -C 12 ) (C 1 - C 12 ) alkyl or aryl.

20. A The radiation-sensitive composition according to claim 19 , wherein the C 1 -C 12 alkyl group R 3 in unit D of the copolymer comprises at least one hydroxy group and at least one substituent selected from the group consisting of halogen and —NO 2 .

21. A radiation-sensitive composition according to claim 19 , wherein the C 3 -C 8 alkyl group comprises at least one hydroxy group and at least one substituent selected from the group consisting of halogen and —NO 2 .

22. A radiation-sensitive composition according to claim 19 , wherein the aryl group comprises at least one hydroxy group and at least one substituent selected from the group consisting of halogen, (C 1 -C 12 )alkyl and —NO 2 .

23. A printing plate comprising

(a) a substrate; and

(b) a radiation-sensitive layer coating, wherein the radiation sensitive layer radiation-sensitive coating comprises a copolymer comprising units A, B, and a unit C comprising a cyclic terminal urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and has the formula is represented by

 wherein R 1 is selected such that the homopolymer of A is alkali-soluble, unit B is present in an amount of about 20 to about 70 mol % and has the following formula is represented by

 wherein R 2 is selected such that the homopolymer of B has a glass transition temperature greater than 100° C., preferably a glass transition temperature in the range from about 100 to about 380° C., and the unit C comprising a cyclic terminal urea group is present in an amount of about 10 to about 50 mol % and has the formula is represented by

 wherein X is a spacer group which is preferably selected from the group consisting of

(a) a —(CR 2 ) m — chain,

(b) a —[CH 2 —CH 2 —O] m — chain; and

(c) a —[Si(R 2 )—O] m — unit, wherein m is an integer between 2 and 12, the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer between 1 and 5; and

 Y is a group selected from the group consisting of:

 wherein each R in units A, B, and C, the —(CR 2 ) m — chain, the —[Si(R 2 )—O] m — unit, and group Y represents a bond between the cyclic urea and the spacer group X, or is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, and or halogen.

24. A The printing plate according to claim 23 , wherein the copolymer further comprises unit D, wherein unit D is present in an amount of about 10 to about 50 mol % and has the formula is represented by

wherein R 3 is selected such that the homopolymer of D is water-solubleand R is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, and halogen , with the proviso that unit D is different from unit A.

25. A printing plate according to claim 23 wherein the substrate is an aluminum substrate laminated onto a polyethyleneterephthalate film having a hydrophilic surface.

26. A method for producing a printing plate comprising:

(a) providing a substrate;

(b) preparing a solution of a radiation-sensitive composition in an organic solvent,

wherein the radiation-sensitive composition comprises

(i) at least one novolak;

(ii) at least one naphthoquinone diazide derivative; and

(iii) a copolymer comprising units A, B, and a unit C comprising a cyclic terminal urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and has the formula is represented by

 wherein R 1 is selected such that the homopolymer of A is alkali-soluble, unit B is present in an amount of about 20 to about 70 mol % and has the following formula is represented by

 wherein R 2 is selected such that the homopolymer of B has a glass transition temperature greater than 100° C., preferably a glass transition temperature in the range from about 100 to about 380° C., and the unit C comprising a cyclic terminal urea group is present in an amount of about 10 to about 50 mol % and has the formula is represented by

 wherein X is a spacer group which is preferably selected from the group consisting of (a) a —CR 2 ) m — chain, (b) a —[CH 2 —CH 2 —O] m — chain; and (c) a —[Si(R 2 )—O] m — unit, wherein m is an integer between 2 and 12, the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer between 1 and 5; and

 Y is a group selected from the group consisting of

 wherein each R in units A, B, and C, the —(CR 2 ) m — chain, the —[Si(R 2 )—O] m — unit, and group Y represents a bond between the cyclic urea and the spacer group X, or is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, and halogen;

(c) applying the solution prepared in step (b) to the substrate; and

(d) drying the solution.

27. A The method according to claim 26 , wherein the copolymer further comprises unit D, wherein unit D is present in an amount of about 10 to about 50 mol % and has the formula is represented by

wherein R 3 is selected such that the homopolymer of D is water-soluble and R is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, and halogen , with the proviso that unit D is different from unit A.

28. The copolymer according to claim 1 , wherein unit A of the copolymer is derivable from methacrylic acid.

29. The copolymer according to claim 1 , wherein unit B of the copolymer is derivable from N-phenylmaleimide, N-cyclohexylmalemide, or a combination thereof.

30. The copolymer according to claim 1 , wherein unit C of the copolymer is derivable from a monomer represented by

31. The copolymer according to claim 4 , wherein unit D of the copolymer is derivable from metharcylamide, N-methoxymethyl methacrylamide, or a combination thereof.

32. The printing plate according to claim 23 , wherein unit A of the copolymer is derivable from methacrylic acid.

33. The printing plate according to claim 23 , wherein unit B of the copolymer is derivable from N-phenylmaleimide, N- cyclohexylmaleimide, or a combination thereof.

34. The printing plate according to claim 23 , wherein unit C of the copolymer is derivable from a monomer represented by

35. The printing plate according to claim 24 , wherein unit D of the copolymer is drivable from methacrylamide, N- methoxymethyl methacrylamide, or a combination thereof.

36. In a printing plate having a substrate with a hydrophilic surface and an imageable coating on the hydrophilic surface and comprising one or more layers, the improvement comprising:

including a copolymer in at least one layer of the imageable coating, the copolymer comprising units A, B, and a unit C comprising a cyclic urea group, wherein unit A is present in an amount of about 5 to about 50 mol % and is represented by

wherein R 1 is selected such that the homopolymer of A is alkali - soluble, unit B is present in an amount of about 20 to about 70 mol % and is represented by

wherein R 2 is selected such that the homopolymer of B has a glass transition temperature greater than 100 ° C., and the unit C comprising a cyclic urea group is present in an amount of about 10 to about 50 mol % and is represented by

wherein X is a spacer group selected from the group consisting of ( a ) a— ( CR 2 ) m — chain, ( b ) a —[CH 2 —CH 2 —O] m — chain; and ( c ) a —[Si ( R 2 ) —O] m — unit, wherein m is an integer between 2 and 12 , the spacer group is connected to one of the carbon ring atoms of the cyclic urea unit or to one of the nitrogen atoms of the cyclic urea unit, and n is an integer between 1 and 5 ; and

wherein each R represents a bond between the cyclic urea and the spacer group X or is independently selected from hydrogen, aryl, (C 1 -C 12 ) alkyl, or halogen.

37. The printing plate of claim 36 , wherein unit a of the copolymer is derivable from methacrylic acid.

38. The printing plate of claim 36 , wherein unit B of the copolymer is derivable from N- phenylmaleimide, N - cyclohexylmaleimide, or a combination thereof.

39. The printing plate of claim 36 , wherein unit C of the copolymer is derivable from a monomer represented by

40. The printing plate of claim 36 , wherein the copolymer further comprises unit D, wherein unit D is present in an amount of about 10 to about 50 mol % and is represented by

wherein R 3 is selected such that the homopolymer of D is water - soluble, with the proviso that unit D is different from unit A.

41. The printing plate of claim 40 , wherein unit D of the copolymer is derivable from methacrylamide, N- methoxymethyl methacrylamide, or a combination thereof.

42. The printing plate of claim 36 , wherein the imageable coating comprises:

a radiation - sensitive top layer; and

a second layer between the hydrophilic surface and the top layer;

wherein the copolymer is included in the second layer.

43. The printing plate of claim 42 , wherein the second layer further comprises a photothermal conversion material.