Claims
- 1. A method of producing a polypropylene fiber, said method comprising the sequential steps of
a) providing a polypropylene composition in pellet or liquid form comprising at least 10 ppm of a nucleating agent; b) melting and mixing said polypropylene composition of step “a” to form a substantially homogeneous molten plastic formulation; c) extruding said plastic formulation to form a fiber structure, d) mechanically drawing said fibers; and e) exposing said drawn fiber of step “d” to a temperature of at least 110° C.;
wherein the temperature at which step “d” is performed is below that at which step “e” is performed.
- 2. A method of producing a polypropylene fiber as in claim 1, wherein the temperature in the drawing step “d” is less than 100° C.
- 3. A method of producing polypropylene fiber as in claim 2, wherein the fiber is exposed to a high temperature in step “e” for at most 1 second.
- 4. A method of producing polypropylene fiber as in claim 1, wherein the fiber exhibits a shrinkage at 150° C. in hot air of at most 7%.
- 5. The method of producing polypropylene fiber as in claim 1, wherein the fiber exhibits a shrinkage at 100° C. in boiling water of at most 3%.
- 6. The method of producing polypropylene fiber as in claim 1, wherein said nucleating agent of step “a” is present in an amount of at least 100 ppm.
- 7. The method of producing polypropylene fiber as in claim 6, wherein said nucleating agent of step “a” is present in an amount of at least 1250 ppm.
- 8. The method of claim 1 wherein said nucleating agent of step “a” is selected from the group consisting of p-MDBS, 3,4-DMDBS, 2,4,5-TMDBS, Liquid 3,4-DMDBS, DBS, sodium benzoate, NA-11, NA-21, and any mixtures thereof.
- 9. The method of claim 8 wherein said nucleating agent is p-MDBS.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of co-pending application Ser. No. 09/860,130, filed on May 17, 2001. This parent application is herein entirely incorporated by reference.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09860130 |
May 2001 |
US |
Child |
10609716 |
Jun 2003 |
US |