Radiation curable compositions

1. An ethylenically unsaturated hydroxyl-terminated polyurethane (I) obtained by reacting

(i) at least one ethylenically unsaturated compound (A) containing at least two reactive groups capable of reacting with isocyanate groups and at least one ethylenically unsaturated group,

wherein the at least one ethylenically unsaturated compound (A) is selected from the group consisting of polyester (meth)acrylates comprising hydroxyl groups, polyepoxy (meth)acrylates comprising hydroxyl groups, and mixtures thereof, or

wherein at least one ethylenically unsaturated compound (A) is selected from compounds that are obtained from partial esterification of aliphatic and/or aromatic polyhydric polyols with (meth)acrylic acid and have a residual average hydroxyl functionality of at least 2.0 in the molecule; with

(ii) at least one saturated alcohol component (B) comprising:

(iia) at least one saturated hydroxylated compound (B1) containing hydrophilic groups capable of rendering the polyurethane dispersible in aqueous medium either directly or after the reaction with a neutralizing agent to provide a salt, and, optionally, at least one compound (B2) that is selected from saturated polyester polyols (B21) and/or from saturated polycarbonate polyols (B22); and/or

(iib) at least one compound (B3) that is selected from saturated polyester polyols (B31) containing compound (B1) moieties and/or from saturated polycarbonate polyols (B32) containing compound (B1) moieties; and, optionally, one or more of compounds (B1) and/or (B2);

(iii) optionally, at least one ethylenically unsaturated compound (C) containing essentially one reactive group capable of reacting with isocyanate groups; and

(iv) at least one polyisocyanate (D) selected from m-tetramethylxylenediisocyanate, p-tetramethylxylenediisocyanate, mixtures thereof, or derivatives thereof,

wherein compound (A) is used in an amount of from 25 to 65% by weight, relative to the total weight of polyurethane (I), and

wherein the groups capable of reacting with isocyanate groups are hydroxyl groups, and wherein the polyurethane (I) has a hydroxyl value of between 5 and 60 mg KOH/g.

2. The polyurethane according to claim 1 , wherein the polyurethane (I) optionally, further is prepared from (v) at least one further polyisocyanate different from said tetramethylxylenediisocyanate, if component (B) comprises one or more of compounds (B2) and/or (B3).

3. The polyurethane according to claim 1 , wherein compounds (A) through (D) are used in such an amount that the ratio between the isocyanate groups and between the reactive groups capable of reacting with said isocyanate groups is between 0.5 and 0.95.

4. The polyurethane according to claim 1 , wherein the isocyanate content is between 0 and 0.05% based on the weight of the polyurethane (I).

5. The polyurethane according to claim 1 , wherein, relative to the total weight of the polyurethane (I), from 25 to 65% by weight of compounds (A) are reacted with from 5 to 40% by weight of components (B), from 0 to 20% by weight of compounds (C), and from 20 to 50% by weight of polyisocyanates (D).

6. The polyurethane according to claim 1 , wherein compounds (A) are obtained from the reaction of diglycidyl compounds with (meth) acrylic acid.

7. The polyurethane according to claim 1 , wherein component (B) consists of at least one compound (B1), and, optionally one or more compounds (B2).

8. The polyurethane according to claim 1 , wherein component (B) consists of least one compound (B3) and, optionally, one or more compounds (B1) and/or (B2).

9. The polyurethane according to claim 1 , wherein compound (C) is selected from (meth)acryloyl mono-hydroxy compounds.

10. The polyurethane according to claim 1 , wherein the polyisocyanate (D) consists of tetramethylxylenediisocyanate (TMXDI).

11. A radiation curable composition comprising at least one polyurethane (I) according to claim 1 .

12. The composition according to claim 11 comprising, relative to the total amount of polyurethane (I) and of compounds (E), from 60 to 100% by weight of the polyurethane (I), and, optionally from 0 to 40% by weight of at least one (meth) acryloyl-compound (E) with a hydroxyl value of less than 25.

13. The composition according to claim 11 which is an aqueous composition having a total solids content of at least 35% by weight.

14. The composition according to claim 11 , which is produced according to a solvent free process.

15. A coating composition, ink or varnish comprising at least one polyurethane (I) according to claim 1 or a radiation curable coating composition comprising at least one polyurethane (I) according to claim 1 .

16. An article coated, entirely or in part, with a coating composition according to claim 15 .

17. The polyurethane according to claim 1 , wherein the derivatives of m-tetramethylxylenediisocyanate and/or p-tetramethylxylenediisocyana are adducts or prepolymers prepared from m-tetramethylxylenediisocyanate, p-tetramethylxylenediisocyanate, and polyols.