Thermoplastic compositions and nonwoven webs prepared therefrom

A nonwoven web comprised of fibers prepared from a melt-extrudable thermoplastic composition which comprises a thermoplastic polyolefin and an additive system comprising a first component and a second component, in which:

• (A) said first component is a polysiloxane polyether having the general formula, ##STR11## in which:
• (1) R.sub.1 -R.sub.9 are independently selected monovalent C.sub.1 -C.sub.3 alkyl groups;
• (2) R.sub.10 is hydrogen or a monovalent C.sub.1 -C.sub.3 alkyl group;
• (3) m represents an integer of from 1 to about 100;
• (4) n represents an integer of from 0 to about 100;
• (5) the sum of m and n is in the range of from 1 to about 100;
• (6) p represents an integer of from 0 to about 5;
• (7) x represents an integer of from 1 to about 25;
• (8) y represents an integer of from 0 to about 25;
• (9) the ratio of x to y is equal to or greater than 2;
• (10) said first component has a weight-average molecular weight of from about 350 to about 18,000;
• and
• (11) said first component is present in an amount of from about 0.1 to about 3 percent by weight, based on the amount of thermoplastic polyolefin;
• and
• (B) said second component is a hydrophobic fumed silica, in which the weight ratio of said first component to said second component is in the range of from about 20 to about 300.

A wettable nonwoven web which (i) is wettable immediately after its formation without any post-formation treatment, (ii) remains wettable after its formation for at least two years at ambient temperature, and (iii) employs a reduced amount of a surface-segregatable first component, which web comprises fibers prepared from a melt-extrudable thermoplastic composition which comprises a thermoplastic polyolefin and an additive system comprising a first component and a second component, in which:

• (A) said first component is a polysiloxane polyether having the general formula, ##STR12## in which:
• (1) R.sub.1 -R.sub.9 are independently selected monovalent C.sub.1 -C.sub.3 alkyl groups;
• (2) R.sub.10 is hydrogen or a monovalent C.sub.1 -C.sub.3 alkyl group;
• (3) m represents an integer of from 1 to about 4;
• (4) n represents an integer of from 0 to about 3;
• (5) the sum of m and n is in the range of from 1 to about 4;
• (6) p represents an integer of from 0 to about 5;
• (7) x represents an integer of from 1 to about 10;
• (8) y represents an integer of from 0 to about 5;
• (9) the ratio of x to y is equal to or greater than 2;
• (10) said first component has a weight-average molecular weight of from about 350 to about 1,200;
• and
• (11) said first component is present in an amount of from about 0.1 to about 3 percent by weight, based on the amount of thermoplastic polyolefin;
• and
• (B) said second component is a hydrophobic fumed silica, in which the weight ratio of said first component to said second component is in the range of from about 20 to about 300.