Process for making microporous fibers with improved properties

• US 5,762,840 A
• Filed: 09/04/1996
• Issued: 06/09/1998
• Est. Priority Date: 04/18/1996
• Status: Expired due to Fees

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Inventors: Topolkaraev, Vasily Aramovich, Tsai, Fu-Jya
• Primary Examiner(s): Tentoni, Leo B.
• Application Number:
  US08/697,996
• Time in Patent Office: 643 Days
• Field of Search: 264/41, 264/129, 264/154, 264/210.4, 264/210.5, 264/210.6, 264/210.7, 264/210.8, 264/235.6, 264/288.8, 264/289.6, 264/290.5, 264/346, 425/66, 425/71, 425/90, 425/93, 425/445, 28/220, 28/240
• US Class Current: 264/41
• CPC Class Codes: D01D 5/16 using rollers, or like mechanical devices, e.g. snubbing pins
• CPC Class Codes: D01D 5/247 Discontinuous hollow structure or microporous structure
• CPC Class Codes: D01F 1/10 Other agents for modifying properties
• CPC Class Codes: D02J 1/22 Stretching or tensioning, shrinking or relaxing, e.g. by use of overfeed and underfeed apparatus, or preventing stretch stretch spinning D01D5/12

Abstract

A distinctive technique for making porous fiber includes a stretching of a substantially continuous fiber while the fiber is in an operative association with an effective quantity of surface-active material. The fiber can be produced from a source material which includes a thermoplastic, orientable material and at least about 0.35 weight percent (wt %) of a supplemental material. In particular configurations of the invention, the fiber may be contacted with a first quantity of surface-active fluid and at least a separate, second quantity of surface-active fluid. In other configurations, the fiber may be subjected to an additional incremental stretching.

Claims

1. A method for making porous fiber, comprising a formation-stretching of a substantially continuous fiber while said fiber is in an operative association with an effective formation-quantity of surface-active material;

said fiber having been produced from a source material which includes a thermoplastic, orientable material, and at least about 0.35 wt % of a supplemental material; and

said fiber having been pretreated with a prior first quantity of surface-active fluid and incrementally stretched.

3. A method as recited in claim 1, wherein said surface-active fluid is a liquid.

4. A method as recited in claim 1, wherein said first quantity of surface-active fluid has been provided with a composition which is substantially the same as a composition of said formation-quantity of surface-active fluid.

5. A method as recited in claim 1, wherein said surface-active fluid provides a surface tension which is less than the critical surface tension of the fiber material.

6. A method as recited in claim 1, wherein said first quantity of surface-active fluid has been provided with a composition which is different than a composition of said formation-quantity of surface-active fluid.

7. A method as recited in claim 1, wherein said fiber has been produced from a source material which includes said thermoplastic, orientable material, and at least about 0.5 wt % of a supplemental material.

8. A method as recited in claim 1, wherein said fiber has been produced from a source material which includes said thermoplastic, orientable material and a supplemental material which provides not less than about 0.5 wt % of a porosity-initiating particulate material, as determined with respect to a total weight of said source material.

9. A method as recited in claim 1, wherein said fiber has been produced from a source material which includes said thermoplastic, orientable material and a supplemental material which includes not less than about 5 wt % of a porosity-initiating particulate material.

10. A method as recited in claim 9, wherein said fiber has been produced from a source material which includes said thermoplastic, orientable material;

and a supplemental material which includes at least about 0.1 wt % of a surface-active material.

11. A method as recited in claim 10, wherein said fiber has been produced from a source material which includes said thermoplastic, orientable material;

and a supplemental material which provides at least about 1 wt % of a surface-active material.

12. A method as recited in claim 1, wherein said fiber has been produced from a source material which includes said thermoplastic, orientable material and a supplemental material which provides at least about 10 wt % of a porosity-initiating particulate material.

13. A method as recited in claim 1, further comprising a heat-setting of said fiber after said fiber has been stretched.

14. A method as recited in claim 1, further comprising an accumulating of said porous fiber at a rate of at least about 900 m/min.

15. A method as recited in claim 1, further comprising an accumulating of said porous fiber at a rate of at least about 1000 m/min.

16. A method as recited in claim 1, wherein said fiber has been incrementally stretched at a temperature of at least about 10°

C.

17. A method as recited in claim 1, wherein said fiber has been incrementally stretched at a draw ratio of not less than about 1.1.

18. A method as recited in claim 1, wherein said fiber has been incrementally stretched at a draw ratio of not more than about 10.

19. A method as recited in claim 1, wherein said formation-stretching provides a draw ratio of not less than about 1.1.

20. A method as recited in claim 1, wherein said formation-stretching provides a draw ratio of not more than about 10.

21. A method as recited in claim 1, wherein said fiber has been subjected to a draw-down ratio of not less than about 5.

22. A method as recited in claim 1, wherein said fiber has been subjected to a draw-down ratio of not more than about 1000.

2. A method for making porous fiber, comprising:

supplying substantially continuous fiber which has been produced from a source material which includes a thermoplastic, orientable material and at least about 0.35 wt % of a supplemental material;

pretreating said fiber with a first quantity of surface-active fluid;

incrementally stretching said pretreated fiber; and

formation-stretching said fiber while said fiber is in an operably effective contact with a second quantity of surface-active fluid.

23. A method as recited in claim 2, wherein said formation-quantity of surface-active fluid is provided as a liquid bath with which said fiber is contacted during said formation-stretching.

24. An apparatus for making porous fiber, comprising:

a source for supplying a substantially continuous fiber which has been produced from a source material which includes a thermoplastic, orientable material and at least about 0.35 wt % of a supplemental material;

an applicator for pretreating said fiber with a first quantity of surface-active fluid;

a first elongating mechanism for incrementally stretching said pretreated fiber;

a mechanism for applying a second quantity of surface-active fluid to said fiber; and

a second elongating mechanism for stretching said fiber in while said fiber is in an operably effective contact with a second quantity of surface-active fluid.

25. A method for making porous fiber, comprising:

pretreating a substantially continuous fiber with a first quantity of surface-active fluid;

incrementally stretching said pretreated fiber; and

formation-stretching said fiber while said fiber is in an operative contact with a second quantity of a surface-active fluid.