SUBSTANTIALLY FLUID-IMPERVIOUS MICROBUBBLED POLYMERIC WEB AND METHOD AND APPARATUS FOR MAKING IT

A microbubbled, substantially fluid-impervious polymeric web exhibiting substantially the same consumer preferred soft and cloth-like tactile impression and low noise generation levels heretofore only achievable in microapertured, and hence substantially fluid pervious, polymeric webs. In a particularly preferred embodiment, the present invention pertains to a microbubbled polymeric web exhibiting a fine-scale pattern of discrete mushroom-shaped surface aberrations, each of said surface aberrations having its amplitude oriented substantially perpendicular to the surface in which the surface aberration originates. However, unlike microapertured webs which are fluid pervious, at least one tiny, continuous membrane bubble, i.e., a microbubble, is provided substantially coincidental with the maximum amplitude of each surface aberration. Thus, the microbubbled web is substantially fluid-impervious. In addition, such a web employing the fine-scale pattern of microbubbled surface aberrations does not exhibit the "rattling" or "rustling" noises typically exhibited by prior art fluid-impervious polymeric webs when subjected to movement. As a result, webs of the present invention have particular utility in environments such as substantially fluid-impervious backsheets for disposable infant diapers and adult incontinent diapers. The microbubbled webs are preferably formed by supporting a web of polymeric film on a moving forming structure and applying a liquid to the exposed surface of the web to permanently deform the web in the image of the forming structure. This is preferably accomplished by subjecting the exposed surface of the web to either a high pressure liquid stream or to hydraulic pressure imposed by a liquid laden deformable roll. The microbubbled webs can be produced either in "planar" or "macroscopically expanded" form.