| 摘要 |
<p>A melt-extrudable thermoplastic polypropylene composition having a melt flow rate in a range of from about 18 to about 30 g/10 minutes at a temperature of 190 °C and a load of 2.16 kg, a polydispersity less than 4, and a Z-average molecular weight greater than 300,000 as determined by differential refractometry. The composition may include a first thermoplastic polypropylene having a melt flow rate lower than 18 g/10 minutes at a temperature of 190 °C and a load of 2.16 kg and a second thermoplastic polypropylene having a melt flow rate higher than 18 g/10 minutes at a temperature of 190 °C and a load of 2.16 kg. The weight ratio of the first polypropylene to the second polypropylene is in a range of from about 90:10 to about 10:90. The composition may include from about 0.1 to about 1 percent by weight, based on the weight of the first and second thermoplastic polypropylenes, of a defined alkyl-substituted polysiloxane. A method of forming a nonwoven web also is provided, which method involves compounding the melt-extrudable thermoplastic polypropylene composition composed of a first and second thermoplastic polypropylene as described above. The compounded thermoplastic composition is melt-extruded through a die to form continuous fibers. The continuous fibers are quenched to a solid state, drawn or attenuated, and randomly deposited on a moving foraminous surface as a web of entangled fibers. The composition may include the alkyl-substituted polysiloxane.</p> |
