Radiation curable aqueous coatings

摘要

Acrylic polymers have been the main source of polymers used for radiation curing compositions with good optical properties, adhesion or outdoor resistance. Blends of acrylic polymer dispersions, obtained by emulsion polymerisation of polyacrylated molecules like trimethylolpropane triacrylate, have been used for a long time. However, the polymer does not contain the ethylenically unsaturated functionality and so does not participate in the crosslinking network after radiation curing. This results in a reduction of the chemical and physical resistance of the coating. Therefore acrylic polymer dispersions with improved chemical and outdoor resistance are required. A composition is given comprising a polymer (1) which is the reaction product of- 1) a water-dispersible (meth) acrylic polymer A containing pendant hydroxyl groups or pendant isocyanate groups capable of enabling the polymer to be water dispersible before or after neutralisation. 2) at least one ethylenically unsaturated compound B, which can be radically polymerised under irradiation and which attaches to the (meth) acrylic polymer A by a urethane linkage; and 3) an optional neutralising agent C.