Retro-reflective liquid coating composition

Claim 1

A coating composition useful, inter alia, to form mound-shaped retroreflective marks that rapidly actuate photoscanner sensing devices, the composition comprising (1) a liquid vehicle that includes (a) a volatile solvent that accounts for at least 90 volume-percent of the vehicle, and (b) a gel agent that when mixed in an amount of less than about 10 volume parts per 100 parts of said solvent forms a gel that will support minute discrete retroreflective elements in a dispersed condition throughout the whole thickness of an applied mark of the gel, said gel agent being included in the vehicle in an amount sufficient to form such a gel and accounting for at least 50 volume-percent of all non-volatile binder material present in the vehicle; and (2) minute discrete retroreflective elements, comprising transparent microspheres and associated specular light-reflecting means, suspended in the vehicle in an amount of at least 50 volume-percent of all non-volatile material in the composition; whereby, the composition may be applied to a surface as a mound-shaped mark, and a portion of the retroreflective elements within the composition will be supported and become optically exposed at the mound-shaped exterior surface of the mark.