Production of radiation curable microcapsular coating compositions,

Abstract

The invention relates to a process for producing a radiation curable coating composition containing microcapsules having a hydrophobic liquid core as follows: An emulsion containing droplets of hydrophobic emulsion component dispersed in a hydrophilic liquid component is prepared. The hydrophobic emulsion component comprises a hydrophobic liquid and a first wall-forming material soluble therein and capable of reacting by condensation polymerization with a second wall-forming material to form a polymeric capsule wall which is substantially insoluble in, and impermeable to, the hydrophilic and hydrophobic emulsion components. The hydrophilic emulsion component comprises an emulsifier and a radiation curable hydrophilic liquid which comprises water and at least one radiation curable polar compound. The emulsion also contains the second wall-forming material. The emulsion is subjected, with stirring, to temperature conditions for a period of time sufficient to react the first and second wall-forming materials to form a dispersion of microcapsules in the hydrophilic emulsion component. The radiation curable dispersion containing a photoinitiator can be coated on a paper substrate and set by subjection to a combination of ultraviolet and infrared radiation for a period of time sufficient to polymerize the radiation curable hydrophilic liquid to a tack-free resinous film on the paper substrate.