Isotactic propylene copolymer fibers, their preparation and use
Fibers comprising a propylene homopolymer or a copolymer of propylene and at least one of ethylene and one or more unsaturated comonomers exhibit desirable properties. The homopolymers are characterized as having 13 C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity. The copolymers are characterized as (A) comprising at least about 60 weight percent (wt %) of units derived from propylene, and (B) having at least one of the following properties: (i) 13 C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity, (ii) a B-value greater than about 1.4 when the comonomer content of the copolymer is at least about 3 wt %, (iii) a skewness index, S ix , greater than about −1.20, (iv) a DSC curve with a T me that remains essentially the same and a T max that decreases as the amount of comonomer in the copolymer is increased, and (v) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst.
1. A fiber comprising an isotactic propylene homopolymer characterized as having 13 C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity.
2. The fiber of claim 1 further characterized as having substantially isotactic propylene sequences.
3. The fiber of claim 2 further comprising a polymer other than an isotactic propylene homopolymer characterized as having 13 C NMR peaks corresponding to a regio-error at about 14.6 and about 15.7 ppm, the peaks of about equal intensity.
4. The fiber of claim 3 in which the fiber is a bicomponent fiber.
5. The fiber of claim 4 in which the other polymer is at least one of an ethylene or α-olefin homopolymer or interpolymer, styrene-based rubber, acrylonitrile-based rubber, natural rubber, thermoplastic polyurethane, epoxy resin, vinyl ester resin, polyester, phenolic resin, a homopolymer or copolymer of vinyl chloride or vinylidene chloride, acrylate resin, nylon and polycarbonate.
6. The fiber of claim 1 blended with other forms of fiber.
7. The fiber of claim 1 blended with cotton fibers.
8. The fiber of claim 1 blended with polyester fibers.
9. A fabric comprising the fiber of claim 1 .
10. The fabric of claim 9 which is woven.
11. The fabric of claim 9 which is nonwoven.
12. Carpet, synthetic hair, a feminine hygiene product, a diaper, athletic sportswear, apparel, upholstery, bandages and sterilizable medical apparel and instrument wraps comprising the fiber of claim 1 .