Patent ID: 8664336

Claim:
A method for forming one or more fibers, the method comprising: (i) charging to a reactive extruder a first polymer and a second polymer to form an initial blend, where the first polymer is a propylene-based elastomer including up to 35% by weight ethylene-derived units and a heat of fusion, as determined according to DSC procedures according to ASTM E-793, of less than 80 J/g and a melt temperature of less than 110° C., where the second polymer is a propylene-based polymer having a melt temperature in excess of 110° C. and a heat of fusion in excess of 80 J/g; (ii) after said step of charging, charging a peroxide to the initial blend to thereby form a reactive blend; (iii) conducting the reactive blend at a flow rate through a series of barrels within the extruder; (iv) subjecting the reactive blend, in one or more barrels, to high shear mixing; (v) maintaining the temperature of the reactive blend at a temperature sufficient to decompose at least 50% of the peroxide and thereby form a reacted blend; (vi) restricting flow rate of the reacted blend through one or more barrels to increase the time that the reactive blend is subjected to the high shear mixing; (vii) increasing flow rate of the reacted blend through one or more barrels; (viii) after said step of increasing the flow rate, passing the reacted blend through one or more screens to thereby remove unwanted contaminates; (ix) extruding the reacted blend through a plurality of die capillaries to form one or more molten threads or filaments; and (x) attenuating the molten threads or filaments in a gas stream to form one or more meltblown fibers.