SHAPED ARTICLES HAVING IMPROVED PROPERTIES

摘要

A melt-extrudable thermoplastic composition is proved which includes a thermoplastic polymer and an improved additive system comprising particles of a solid material, in which substantially all of the particles have a longest dimension in the range of from about 0.001 to about 1 micrometer and the surfaces of the particles have a surface free energy which is equal to or less than the surface free energy of the thermoplastic polymer. Alternatively, the particles can be coated with a material which results in coated particle surfaces having a surface free energy which is equal to or less than the surface free energy of the thermoplastic polymer. In one embodiment, a melt-extrudable thermoplastic composition is provided which includes a thermoplastic polyolefin and an improved additive system made up of a first component and a second component, in which (A) the first component is a defined alkyl-substituted polysiloxane having a number-average molecular weight of from about 3,000 to about 36,000 and which is present in an amount of from about 0.01 to about 3 percent by weight, based on the amount of thermoplastic polyolefin; and (B) the second component is a hydrophobic fumed silica, in which the weight ratio of the first component to the second component is in the range of from about 10 to about 70. In a desired embodiment, the particles of second component are in the range of from about 0.001 to about 1 micrometer. The composition yields, upon melt extrusion, nonwoven webs having significantly increased tensile strengths when compared to nonwoven webs prepared from the thermoplastic polyolefin alone.