Polypropylene Fibers and Spunbond Nonwoven with Improved Properties
The present invention relates to a process for the production of polypropylene fibers and polypropylene spunbond nonwoven comprising a degradation step, wherein the melt flow of the polypropylene is increased, and a fiber or filament extrusion step. The present invention also relates to the fibers and nonwoven produced with said process and to composites and laminates comprising said fibers and nonwoven.
1 - 11 . (canceled)
12 . A process for the production of polypropylene fibers or polypropylene spunbond nonwovens comprising:
thermally or chemically degrading a Ziegler-Natta polypropylene from a first melt flow MFI 1 (ISO 1133, 230° C., 2.16 kg) to a second melt flow MFI 2 (ISO 1133, 230° C., 2.16 kg) such that the second melt flow MFI 2 is at least 50 dg/min and at most 300 dg/min and such that the degradation ratio MFI 1 /MFI 2 is at least 0.10 and at most 0.8;
extruding the second melt flow polypropylene to obtain filaments; and
rapidly reducing the diameter of the filaments to a final diameter.
13 . The process of claim 12 , wherein the second melt flow MFI 2 (ISO 1133, 230° C., 2.16 kg) of the polypropylene is at least 55 dg/min.
14 . The process of claim 12 , wherein the second melt flow MFI 2 (ISO 1133, 230° C., 2.16 kg) of the polypropylene is at most 200 dg/min.
15 . The process of claim 12 , wherein the degradation ratio MFI 1 /MFI 2 is at least 0.12.
16 . The process of claim 12 , wherein the degradation ratio MFI 1 /MFI 2 is at most 0.7.
17 . The process of claim 12 , wherein the final diameter of the filaments is at most 2.0 denier per filament.
18 . The process of claim 12 , wherein the final diameter of the filaments is at least 0.5 denier per filament.
19 . The process of claim 12 , wherein the polypropylene is a polypropylene homopolymer.
20 . Fibers or nonwoven formed from the process of claim 12 .
21 . Composites and laminates comprising the fibers and nonwovens of claim 20 .