Method of making transfer sheets and resulting article

Claim 1

TRANSFER SHEET MATERIAL FOR USE IN MANIFOLDING WHICH COMPRISES A BASE WEB AND A SUBSTANTIALLY COLOURLESS COATING CARRIED UPON A SURFACE OF THE BASE WEB, THE COATING BEING CONSTITUTED BY A CONTINUOUS PHASE OF THE COATING TINUOUS PHASE, THE DISCONTINUOUS PHASE OF THE COATING COMPRISING A PLURALITY OF DISCRETE PARTICLES OF PRESSURERESPONSIVE SPONGE-LIKE MATERIAL HAVING A PARTICLES ABOUT 3 TO ABOUT 10 MICRONS, AND THE SPONGE-LIKE PARTICLES HAVING ABSORBED THEREIN A COLOUR-FORMING FLUID MATERIAL CONTAINING A COLOURLESS DERIVATIVE OF A DYESTUFF ADAPTED ON BE CONVERTED INTO THE CORRESPONDING COLOURED DYESTUFF ON REACTION WITH AN ACID SUBSTANCE, THE CONTINUOUS PHASE OF THE COATING CONSISTING OF A DRY AND HARD BUT PREVIOUS FILM SUFFICIENTLY FRIABLE TO PERMIT THE COLOUR-FORMING FLUID MATERIAL TO PASS THERETHROUGH, THE PRESSURE-RESPONSIVE, SPONGE-LIKE PARTICLES BEING ADAPTED NORMALLY TO RETAIN THE COLOUR-FORMING FLUID MATERIAL BUT TO PERMIT IT TO BE EXPRESSED THROUGH THE FRIABLE FILM, WHEN THE TRANSFER SHEET MATERIAL IS SUBJECTED TO WRITING PRESSURE, AND THEREBY TO BE TRANSFERRED TO A COPY SHEET IN CONTACT WITH THE COATED SURFACE OF THE SHEET MATERIAL.