Adhesive sheet and method of making

An adhesive sheet material capable of being slid into position on an adhesive-receptive work-surface and of then being adhesively anchored in the position by simple application of pressure, includes a thin continuous layer of adhesive having a pebbly contour provided by a uniform pattern of small protrusions of the adhesive separted by intervening planar adhesive surfaces, the protrusion being individually capped with continuous non-adhesive fragile protective converings extending over one-fourth the height of the protrusions. The protrusions may extend for 0.025 to 0.25 mm above the adhesive surfaces and the area covered by the protrusions is one-tenth to one-third the total surface area of the adhesive layer. The height of the protrusions is preferably not less than 15 microns and the distance between protrusions should be not less than one-fourth the maximum diameter of the protrusions. The adhesive may be a pressure sensitive adhesive an example of which is given. The protective covering may be a fragile non-adhesive polymeric material, e.g. vinyl polymers, epoxy resins, alkyd resins, methacrylatestyrene copolymers, sodium silicate and inorganic film forming materials, polymethyl methacrylate resin. The sheet material may have a coextensive adhesive-protecting removable sheet material having an adhesive release surface closely conforming to the capped protrusions and planar adhesive surfaces. The adhesive sheet material may be produced by shaping the adhesive surface into a pebbly contour having a pattern of small protrusions and intervening planar surfaces, and capping the protrusions with non-adhesive continuous fragile protective caps extending over one fourth the height of the protrusions. A fluid coating composition, e.g. a methacrylate polymer, is applied to a temporary carrier which has a smoothly pitted adhesive release surface in an amount just sufficient to provide a protective cap in each pit; thereafter either (1) the composition is hardened, and the carrier is coated with a thin continuous layer of pressure sensitive adhesive so as to fill the remainder of the depressions thereby forming the pebbly contour with the protective cap extending thereover, a carrier sheet may then be applied to the adhesive layer; or (2) an adhesive-carrying sheet is pressed against the carrier so as to force the adhesive into the depressions thereby forming the pebbly surface with a protective cap over each protrusion. The protrusions may be of hemispherical, c