Radiation curable composition

A radiation curable composition (X) comprising at least one (meth)acrylated acrylic polymer (AA) comprising pendant hydroxyl groups which is the reaction product of:

• a) at least one water-insoluble (meth)acrylic polymer (AP) comprising pendant hydroxyl groups which is the reaction product of:
• a1) at least one hydroxy functional ethylenically unsaturated monomer (AP1), and
• a2) at least one ethylenically unsaturated monomer (AP2) which is different from (AP1), and
• b) at least one isocyanate group-containing monoadduct (MA) comprising at least one (meth)acrylate group and which attaches to the water-insoluble (meth)acrylic polymer (AP) comprising pendant hydroxyl groups by a urethane linkage and which is the reaction product of:
• b1) at least one polyisocyanate (MA1), and
• b2) at least one hydroxy functional (meth)acrylate monomer (MA2),
• wherein the equivalent ratio of NCO groups to OH groups of the radiation curable composition (X) is from 1:0.5 to 1:10 and the glass transition temperature (Tg) of the radiation curable composition (X) after the acrylation is at least 10° C. and wherein the glass transition temperature (Tg) is measured by dynamic scanning calorimetry (DSC) according to the standard ASTM E1356-08,
• wherein the hydroxyl number IOH of the radiation curable composition (X) is comprised from 20 to 350 mgKOH/g,
• wherein the hydroxyl number IOH is measured by the following method:
• step 1—acetylation step:
• all hydroxyl functions are acetylated at 75° C. by acetic chloride;
• step 2—the excess of acetic chloride is hydrolysed by a solution of N-methyl-2-pyrrolidone (NMP) in water;
• and
• step 3—titration step:
• The formed acid functions are titrated with KOH 0.5 N solution,
• wherein the radiation curable composition (X) is water-insoluble, and
• wherein the radiation curable composition (X) is a non-aqueous composition.