Patent ID: 8231377

Claim:
An apparatus for stretching a sheet material consisting essentially of: a pair of cylindrical rolls positioned in opposed cooperating relation for receiving a sheet material therebetween, a plurality of projections on at least one of said rolls, each projection including a body extending radially outwardly and a cap having outermost surface portions positioned for contacting the sheet material, the outermost surface portion of each cap having a semi-spherical shape, wherein the cap has a cross-section that is wider than that of the body such that the projections have a mushroom-like shape, and a corresponding plurality of recesses on the other one of said rolls, said recesses being positioned and arranged to receive corresponding projections of said at least one roll, wherein the pair of rolls are configured to stretch the sheet material such that the projections, upon entering the recesses, engage and stretch isolated discrete portions of the sheet material to form a plurality of free standing stretched regions in the sheet material that are separated from each other by substantially unstretched regions.