05.07.12
A nonwoven fabric based on polypropylene elastomers has been patented. The nonwoven is made from a composition prepared by combining:
a. from 10% to 40% by weight, based on the weight of the total composition, of a first propylene-based polymer blend prepared by combining (i) 90 to 70 wt %, by weight of the first propylene-based polymer blend, of a first propylene-based elastomer having an Mw/Mn of 1.8 to 5 with (ii) at least 5 to about 17 wt %, by weight of the first propylene-based polymer blend, of a first propylene-based thermoplastic resin, where said first blend has an MFR (ASTM D-1238 2.1.6 kg @ 230° C.) equal to or less than 40 dg/min; with
b. from 90% to 60% by weight, based on the weight of the total composition, of a second propylene-based polymer blend prepared by combining (i) 90 to 70 wt %, by weight of the second propylene-based polymer blend, of a second propylene-based elastomer having an Mw/Mn of 1.8 to 5 with (ii) at least 5 to about 17 wt %, by weight of the second propylene-based polymer blend, of a second propylene-based thermoplastic resin, where the second propylene-based polymer blend has been vis-broken to an MFR (ASTM D-1238 2.16 kg @ 230° C.) greater than 60 dg/min; where the propylene-based elastomers comprise from about 5% to 35% by weight units derived from ethylene or non-propylene alpha-olefin, the propylene-based elastomer possessing a heat of fusion, as determined by DSC, of less than 80 J/g, and where the propylene-based thermoplastic resins have a heat of fusion, as determined by DSC, equal to or greater than 80 J/g, and wherein the propylene-based thermoplastic resin has a Tm that is greater than 120° C. and an MFR from 10 to 50 dg/min (ASTM D-1238 2.16 kg @ 230° C.); and wherein the first and second propylene-based polymer blends form a composition that has a bimodal molecular weight distribution.
a. from 10% to 40% by weight, based on the weight of the total composition, of a first propylene-based polymer blend prepared by combining (i) 90 to 70 wt %, by weight of the first propylene-based polymer blend, of a first propylene-based elastomer having an Mw/Mn of 1.8 to 5 with (ii) at least 5 to about 17 wt %, by weight of the first propylene-based polymer blend, of a first propylene-based thermoplastic resin, where said first blend has an MFR (ASTM D-1238 2.1.6 kg @ 230° C.) equal to or less than 40 dg/min; with
b. from 90% to 60% by weight, based on the weight of the total composition, of a second propylene-based polymer blend prepared by combining (i) 90 to 70 wt %, by weight of the second propylene-based polymer blend, of a second propylene-based elastomer having an Mw/Mn of 1.8 to 5 with (ii) at least 5 to about 17 wt %, by weight of the second propylene-based polymer blend, of a second propylene-based thermoplastic resin, where the second propylene-based polymer blend has been vis-broken to an MFR (ASTM D-1238 2.16 kg @ 230° C.) greater than 60 dg/min; where the propylene-based elastomers comprise from about 5% to 35% by weight units derived from ethylene or non-propylene alpha-olefin, the propylene-based elastomer possessing a heat of fusion, as determined by DSC, of less than 80 J/g, and where the propylene-based thermoplastic resins have a heat of fusion, as determined by DSC, equal to or greater than 80 J/g, and wherein the propylene-based thermoplastic resin has a Tm that is greater than 120° C. and an MFR from 10 to 50 dg/min (ASTM D-1238 2.16 kg @ 230° C.); and wherein the first and second propylene-based polymer blends form a composition that has a bimodal molecular weight distribution.
