Claims
- 1. A method of forming a nonwoven web comprising the steps of:
- compounding 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.degree. C. and a load of 2.16 kg and comprising
- a first thermoplastic polypropylene having a melt flow rate lower than 18 g/10 minutes at a temperature of 190.degree. 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.degree. C. and a load of 2.16 kg, wherein the weight ratio of the first polypropylene to the second polypropylene is in a range of from about 90:10 to about 10:90;
- forming continuous fibers by extruding the compounded composition through a die;
- quenching the continuous fibers to a solid state;
- drawing the fibers; and
- randomly depositing the fibers on a moving foraminous surface as a web of entangled fibers.
- 2. The method of claim 1, in which the melt-extrudable thermoplastic polypropylene composition further comprises from about 0.1 to about 1 percent by weight, based on the weight of the first and second thermoplastic polypropylenes, of an alkyl-substituted polysiloxane having the general formula, ##STR4## in which: R.sub.1 -R.sub.9 are independently selected monovalent C.sub.1 -C.sub.3 alkyl groups;
- R.sub.10 is a monovalent C.sub.6 -C.sub.30 alkyl group;
- m represents an integer of from about 5 to about 50;
- n represents an integer of from 0 to about 200;
- the alkyl-substituted polysiloxane has a number-average molecular weight of from about 3,000 to about 36,000; and
- the alkyl-substituted polysiloxane has a polydispersity of from about 1.1 to about 2.5.
- 3. The method of claim 1, in which the first polypropylene has a melt flow rate in a range of from about 1 to about 10 g/10 minutes at a temperature of 190.degree. C. and a load of 2.16 kg.
- 4. The method of claim 2, in which the first polypropylene has a melt flow rate in a range of from about 1 to about 10 g/10 minutes at a temperature of 190.degree. C. and a load of 2.16 kg.
- 5. The method of claim 1, in which the second polypropylene has a melt flow rate in a range of from about 20 to about 50 g/10 minutes at a temperature of 190.degree. C. and a load of 2.16 kg.
- 6. The method of claim 2, in which the second polypropylene has a melt flow rate in a range of from about 20 to about 50 g/10 minutes at a temperature of 190.degree. C. and a load of 2.16 kg.
- 7. The method 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 the alkyl-substituted polysiloxane has a number-average molecular weight of from about 8,000 to about 15,000.
Parent Case Info
This application is a continuation of application Ser. No. 08/321,720 entitled "Melt-extrudable Thermoplastic Polyproplyene Composition and Nonwoven Webs Prepared Therefrom" and filed in the U.S. Patent and Trademark Office on Oct. 12, 1994, now abandoned. The entirety of this application is hereby incorporated by reference.
US Referenced Citations (30)
Foreign Referenced Citations (4)
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552 013 |
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Continuations (1)
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Number |
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Parent |
321720 |
Oct 1994 |
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