Selfbonded nonwoven fabrics

Claim 1

An improved process for preparing a fabric having an Elmendorf tear strength (ASTM D-1424), T, of at least 6 lb. and a normalized grab tensile strength, G, of at least 120 lb. (ASTM D-1117) for a 140 gm/meter 2 fabric, and the value of the product T×G being at least 1,200 by a process comprising the steps of melt spinning sheath/core heterofilaments, drawing the spun filaments, laying the drawn filaments to form an unbonded web, and thereafter bonding the web by the application of heat and pressure to form a selfbonded nonwoven fabric without using solvents that are relatively non-volatile at the bonding conditions, wherein the improvement comprises: (i) melt spinning sheath/core heterofilaments, wherein said sheath is high density polyethylene having a solid state density in the range from 0.930 to 0.965 gm/cc and having a melt flow index from 1 to 50 as measured by ASTM D-1238, and wherein said high density polyethylene comprises from 5 to 30 weight percent of said heterofilament; (ii) drawing said spun heterofilaments at a draw ratio within the range 2.0 to 6.0, at a temperature up to 120° C.; and (iii) bonding said unbonded web at a temperature of from 120° to 155° C. at a nip stress in the range of 50 to 140 pounds per square inch, whereby said sheaths are softened.