Patent ID: 8313822

Claim:
A pressure-sensitive adhesive sheet comprising a sheet-like base and a pressure-sensitive adhesive layer integrally laminated on one side of the sheet-like base, wherein the pressure-sensitive adhesive layer has on the surface thereof two or more waved groove portions, wherein each of the waved groove portions consists essentially of convex arcuate groove portions and concave arcuate groove portions disposed alternately and connected at connecting portions, wherein the two or more waved groove portions are formed at intervals in the amplitude direction of the waved groove portions, wherein a total wavelength of each waved groove portion is constituted by a combined length of one convex arcuate groove portion and one concave groove portion which are connected together, wherein the total wavelengths of adjacent waved groove portions are different from each other, wherein the convex arcuate groove portions and the concave arcuate groove portions are arcs defined by a sine function, wherein each of the waved groove portions is configured such that all of the connecting portions of the convex arcuate groove portions with the concave arcuate groove portions are located on a virtual straight line, and wherein the virtual straight lines of all the waved groove portions are parallel to each other, and the intervals between the virtual straight lines of the waved groove portions are not constant.