Claims
- 1. A melt-extrudable thermoplastic composition which comprises a thermoplastic polyolefin and an improved additive system comprising a first component and a second component, in which:
- (A) said first component is an alkyl-substituted polysiloxane having the general formula, ##STR6## 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 a monovalent C.sub.6 -C.sub.30 alkyl group;
- (3) m represents an integer of from about 5 to about 50;
- (4) n represents an integer of from 0 to about 200;
- (5) said first component has a number-average molecular weight of from about 3,000 to about 36,000; and
- (6) said first component has a polydispersity of from about 1.1 to about 2.5;
- (B) said second component is a hydrophobic fumed silica, in which the weight ratio of the said first component to said second component is in the range of from about 10 to about 70; and
- (C) said improved additive system is present in an amount of from about 0.01 to about 3 percent by weight, based on the amount of thermoplastic polyolefin.
- 2. The composition of claim 1, in which substantially all of said second component is present as particles having a longest dimension in the range of from about 0.001 to about 1 micrometer.
- 3. The composition of claim 2, in which each of R.sub.1 -R.sub.9 is a methyl group, R.sub.10 is a monovalent C.sub.15 -C.sub.22 alkyl group, m represents an integer of from about 15 to about 25, n represents an integer of from about 40 to about 80, and said first component has a number-average molecular weight of from about 8,000 to about 15,000.
- 4. The composition of claim 3, in which said polyolefin is polypropylene.
- 5. The composition of claim 4, in which said polypropylene has a skewed molecular weight range in which the z-average molecular weight/weight-average molecular weight ratio is equal to or greater than about 2 and less than about 5.
- 6. The composition of claim 4, in which said polypropylene is a blend of two propylene polymers having different melt flow rates.
- 7. The composition of claim 6, in which said blend consists of (a) from about 60 to about 40 percent by weight of a polypropylene having a melt flow rate of from about 30 to about 45 and (b) from about 40 to about 60 percent by weight of a polypropylene having a melt flow rate of from about 2 to about 10.
- 8. The composition of claim 3, in which said first component is present in an amount of from about 0.1 to about 0.5 percent by weight, based on the amount of thermoplastic polyolefin.
- 9. The composition of claim 3, in which the weight ratio of said first component to said second component is in the range of from about 10 to about 30.
- 10. A method for preparing a nonwoven web having significantly improved tensile strength characteristics which comprises
- (A) melting a thermoplastic composition which includes a thermoplastic polyolefin and an improved additive system having a first component and a second component;
- (B) forming fibers by extruding the resulting melt through a die;
- (C) drawing the fibers; and
- (D) collecting the fibers on a moving foraminous surface as a web of entangled fibers;
- in which:
- (1) the first component is an alkyl-substituted polysiloxane having the general formula, ##STR7## in which: (a) R.sub.1 -R.sub.9 are independently selected monovalent C.sub.1 -C.sub.3 alkyl groups;
- (b) R.sub.10 is a monovalent C.sub.6 -C.sub.30 alkyl group;
- (c) m represents an integer of from about 5 to about 50;
- (d) n represents an integer of from 0 to about 200;
- (e) the first component has a number-average molecular weight of from about 3,000 to about 36,000; and
- (f) the first component has a polydispersity of from about 1.1 to about 2.5;
- (2) 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; and
- (3) the improved additive system is present in an amount of from about 0.01 to about 3 percent by weight, based on the amount of thermoplastic polyolefin.
- 11. The method of claim 10, in which substantially all of the second component is present as particles having a longest dimension in the range of from about 0.001 to about 1 micrometer.
- 12. The method of claim 11, in which said polyolefin is polypropylene.
- 13. The method of claim 12, in which said polypropylene has a skewed molecular weight range in which the z-average molecular weight/weight-average molecular weight ratio is equal to or greater than about 2 and less than about 5.
- 14. The method of claim 12, in which said polypropylene is a blend of two propylene polymers having different melt flow rates.
- 15. The method of claim 14, in which said blend consists of (a) from about 60 to about 40 percent by weight of a polypropylene having a melt flow rate of from about 30 to about 45 and (b) from about 40 to about 60 percent by weight of a polypropylene having a melt flow rate of from about 2 to about 10.
- 16. The method of claim 10, which includes the additional step of pattern bonding by the application of heat and pressure the web of entangled fibers resulting from step (D).
- 17. A composition which comprises a first component and a second component, in which:
- (A) said first component is an alkyl-substituted polysiloxane having the general formula, ##STR8## 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 a monovalent C.sub.6 -C.sub.30 alkyl group;
- (3) m represents an integer of from about 5 to about 50;
- (4) n represents an integer of from 0 to about 200;
- (5) said first component has a number-average molecular weight of from about 3,000 to about 36,000; and
- (6) said first component has a polydispersity of from about 1.1 to about 2.5; and
- (B) said second component is a hydrophobic fumed silica, in which the weight ratio of the said first component to said second component is in the range of from about 10 to about 70.
- 18. The composition of claim 17, in which substantially all of said second component is present as particles having a longest dimension in the range of from about 0.001 to about 1 micrometer.
- 19. The composition of claim 18, in which each of R.sub.1 -R.sub.9 is a methyl group, R.sub.10 is a monovalent C.sub.15 -C.sub.22 alkyl group, m represents an integer of from about 15 to about 25, n represents an integer of from about 40 to about 80, and said first component has a number-average molecular weight of from about 8,000 to about 15,000.
- 20. A film prepared from the composition of claim 1.
- 21. A film prepared from the composition of claim 2.
- 22. A film prepared from the composition of claim 4.
- 23. A microporous film prepared from the composition of claim 1.
- 24. A microporous film prepared from the composition of claim 2.
- 25. A microporous film prepared from the composition of claim 4.
Parent Case Info
This is a continuation-in-part of application Serial No. 07/958,630, filed on Oct. 9, 1992, abandoned
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
102e Date |
371c Date |
PCT/US93/09748 |
10/12/1993 |
|
|
7/7/1995 |
7/7/1995 |
Publishing Document |
Publishing Date |
Country |
Kind |
WO94/09066 |
4/28/1994 |
|
|
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
5336707 |
Nohr et al. |
Aug 1994 |
|
5344862 |
Nohr et al. |
Sep 1994 |
|
5413655 |
Nohr et al. |
May 1995 |
|
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
958630 |
Oct 1992 |
|