Elastic blends comprising crystalline polymer and crystallizable polymers of propylene

Abstract

Improved thermoplastic polymer blend compositions comprising an isotactic polypropylene component and an alpha-olefin and propylene copolymer component, said copolymer comprising crystallizable alpha-olefin sequences. In a preferred embodiment, improved thermoplastic polymer blends are provided comprising from about 35% to about 85% isotactic polypropylene and from about 30% to about 70% of an ethylene and propylene copolymer, wherein said copolymer comprises isotactically crystallizable propylene sequences and is predominately propylene. The resultant blends manifest unexpected compatibility characteristics, increased tensile strength, and improved process characteristics, e.g., a single melting point.

1 - 31 . (Canceled).  
     
     
         32 . An article of manufacture comprising a copolymer of propylene, ethylene and, optionally, one or more unsaturated comonomers, the copolymer characterized as (A) comprising at least about 88.4 weight percent of units derived from propylene and about 5.8 to about 11.6 weight percent of units derived from ethylene, and (B) having at least one of the following properties: (i) 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 (ii) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst.  
     
     
         33 . The article of  claim 32  in the form of a fiber.  
     
     
         34 . The article of manufacture of  claim 32  characterized further by at least one of the following additional properties: (iii) a B-value of about 1.4 when the comonomer content of the copolymer is about 5.8 weight percent, and (iv) a skewness index, S ix , of about −0.32.  
     
     
         35 . The article of  claim 34  in the form of a fiber.  
     
     
         36 . A fabric comprising the fiber of  claim 33 .  
     
     
         37 . The fabric of  claim 36  which is woven.  
     
     
         38 . The fabric of  claim 36  which is nonwoven.  
     
     
         39 . 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 33 .  
     
     
         40 . The article of manufacture of  claim 34  further comprising a polymer other than the copolymer and characterized as having at least one of the following properties: (i) 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 (ii) an X-ray diffraction pattern that reports more gamma-form crystals than a comparable copolymer prepared with a Ziegler-Natta (Z-N) catalyst.  
     
     
         41 . The article of  claim 40  in the form of a fiber.