Novel fibrous assembly and process for production thereof

A fibrous structure comprising a laminate of at least two fibrous assemblies each of which is spread in a direction at right angles to the longitudinal axes of the fibers of said assembly to form a reticulated structure, and in which many fibers are crimped so that the constituent fibers of the laminate are intertwined three-dimensionally;

• wherein each of said fibrous assembly consists of many fibers, the individual constituent fibers being interconnected at random in a spaced-apart relationship so that when spread in a direction at right angles to the longitudinal axes of the fibers, said assembly can form a continuous integral reticulated structure;
• said individual fibers having asymmetrical irregularly-shaped cross sections of substantially different profiles and sizes from one another when said assembly is cut at right angles to the longitudinal axes of the fibers at an arbitrary point therealong;
• at least 40% of the entire cross-sectional area of each fiber consisting of at least two different polymer phases which are coalesced side-by-side as at least two irregular blocks;
• and each of the individual fibers of said assembly having a non-uniform cross-sectional shape along its longitudinal axis.

A fibrous structure comprising a laminate of at least two fibrous assemblies each of which is spread in a direction at right angles to the longitudinal axes of the fibers of said assembly to form a reticulated structure, and in which many fibers are crimped so that the constituent fibers of the laminate are intertwined three-dimensionally;

• wherein each of said fibrous assemblies consists of many fibers, the individual constituent fibers being interconnected at random in a spaced-apart relationship so that when spread in a direction at right angles to the longitudinal axes of the fibers, said assembly can form a continuous integral reticulated structure;
• said individual fibers having asymmetrical irregularly-shaped cross sections of substantially different profiles and sizes from one another when said assembly is cut at right angles to the longitudinal axes of the fibers at an arbitrary point therealong;
• each of the individual fibers of said assembly having a non-uniform cross-sectional shape along its fiber axis;
• and said constituent fibers having (A) a portion having at least two different polymer phases coalesced side-by-side as at least two irregular blocks, and (B) a portion in which at least one of said at least two different polymer phases is separated from the other polymer phase to form at least two finer fibers.

A process for producing a fibrous assembly, the individual constituent fibers being interconnected at random in a spaced-apart relationship so that when spread in a direction at right angles to the longitudinal axes of the fibers, said assembly can form a continuous integral reticulated structure;

• said individual fibers having asymmetrical irregularly-shaped cross sections of substantially different profiles and sizes from one another when said assembly is cut at right angles to the longitudinal axes of the fibers at an arbitrary point therealong;
• at least 40% of the entire cross-sectional area of each fiber consisting of at least two different polymer phases which are coalesced side-by-side as at least two irregular blocks;
• and each of the individual fibers of said assembly having a non-uniform cross-sectional shape along its longitudinal axis;
• which comprises associating melts of at least two different foamable polymer phases in the form of layers, extruding the associated mass from an elongated slit having a narrow clearance of 30 to 300 microns as superimposed layer-like streams in the direction of the narrow width, simultaneously foaming the polymer phases, and taking up the extrudate at a draft ratio of from 50 to 250 while cooling the extrudate at a location between the slit exit and a point 10 mm below the exit.