Strong nonwoven fabrics from engineered multiconstituent fibers

The present invention provides a thermally-bonded nonwoven fabric that is made from a web which comprises from 100 to 5 percent by weight of multiconstituent fibers. Said multiconstituent fibers are composed of highly dispersed blends of at least two different immiscible thermoplastic polymers and have a dominant continuous polymer phase with at least one noncontinuous phase dispersed therein. The noncontinuous phase exists as an elongated fibrillar polymer domain oriented generally in the direction of the fiber axis. No single polymer domain cross-section of said noncontinuous phase or phases is larger than 0.1% of the cross-sectional area of said fiber. The polymer of the noncontinuous phase or phases has a Polymer Melt Temperature (PMT) at least 30 DEG C below the PMT of the continuous phase. The fiber is configured such that said noncontinuous phase or phases occupy a substantial portion of the fiber surface. In addition to such fabrics, laminates --made by combining nonwoven fabrics made from the materials and processes as described herein with films, paper, tissue, woven fabrics, or nonwoven fabrics such as meltblowns-- are also contemplated. The fabric according to the invention readily bonds to other materials of the sorts mentioned, and is therefore suitable for use in filtration media, medical and clean room garments, CSR wrap, absorbent article backsheets, and other barrier structures.