Patent ID: 6863940

Claim:
A weatherproof sheet suitable for use in a photocopier or laser printer and capable of fixedly and legibly bearing images printed directly thereon by means of the photocopier or laser printer, the weatherproof sheet comprising: a cellulosic substrate having two substantially planar sides; and a durable weatherproofing coating layer, in direct contact with and impregnantly covering at least one of the two sides of the substrate, the coating layer penetrating the surface of the at least one of the two sides of the substrate, wherein the coating layer comprises a copolymer or mixture of copolymers derived from at least one styrene or styrenic monomer and at least one acrylic monomer, a wax, a filler to provide block resistance, a filler to provide tooth for printability and writability, a pigment, and an optical brightener; with the proviso that the coating layer comprises substantially no calcium carbonate filler and substantially no titanium dioxide pigment.