Nonwoven fibrous sheet structures

Abstract

This invention relates to a nonwoven sheet material with high air permeability and substantial hydrostatic head liquid barrier properties. The sheet material is comprised of at least 90%, by weight, melt spun substantially continuous filament polymer fibers having an average cross sectional area of less than about 90 square microns. The sheet material has a basis weight of less than 125 g/m 2 and a grab tensile strength of at least 0.7 N/(g/m 2 ). The invention is also directed to a process for melt spinning polymer fibers that can be used to make the nonwoven sheet material of the invention.

We claim:  
     
         1 . A nonwoven fabric comprising at least one nonwoven layer of spunbond polypropylene fibers, said fabric having a basis weight between about 13-125 g/m 2 , a grab tensile strength in both the machine- and cross-directions between about 0.9 to 3 N/(g/m 2 ), normalized for basis weight, and a combination of Frazier permeability between about 10 and 30 m 3 /min-m 2  and hydrostatic head between about 66 and 99 cm.