American Can Company

Joseph M Guarnery

William R Watt

Dennis E Kester

A polymerizable coating composition comprises 35-80 parts of an epoxy prepolymer material and 20-65 parts of a vinyl chloride dispersion polymer together with 0.5-10 percent by weight, based upon the weight of the epoxy prepolymer material, of an onium salt photoinitiator which decomposes upon exposure to electromagnetic radiation to initiate polymerization of the epoxy prepolymer material. The vinyl chloride polymer has a high molecular weight represented by an inherent viscosity of 0.60-1.60 and a particle size of 0.5-20.0 microns. The coating is applied to the surface of a substrate and then exposed to a source of electromagnetic radiation to decompose the photoinitiator and initiate polymerization of the epoxy prepolymer material to a tack-free surface condition in which the vinyl chloride polymer is dispersed within the epoxy polymer. This is desirably effected by maintaining the coating at a temperature of about 50.degree.-90.degree. C. for a limited time following exposure to radiation. After the coating has been cured to a tack-free condition, it is desirably baked at a temperature of at least 150.degree. C. to effect substantial fusion of the vinyl chloride polymer and cross-linking of the epoxy polymer.

Polymerizable coating composition containing polymerizable epoxide

A method for the high speed coating of various substrates utilizes an epoxy composition containing a radiation-sensitive catalyst precursor which will decompose upon exposure to electromagnetic radiation to provide a Lewis acid effective to induce cationic polymerization of the epoxy composition. The formulation does not require any special epoxy monomeric materials or accelerators and is stable until so exposed. Subsequent to applying the formulation to the substrate, the coating is exposed to electromagnetic radiation and a controlled temperature of 50.degree.-90.degree. C. is maintained in the coating for a limited period of time to effect polymerization of the formulation to a tack free surface condition within a period of less than 30 seconds. Maintenance at the elevated temperature following initiation of irradiation may be for a period of as little as 0.5 second.

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Libertyville, IL, United States of America

Joseph M Guarnery