Low stress relaxation elastomeric fibers

• US 5,288,791 A
• Filed: 04/07/1993
• Issued: 02/22/1994
• Est. Priority Date: 01/10/1990
• Status: Expired due to Term

• Current Assignee: Kimberly-Clark Worldwide Incorporated (Kimberly-Clark Corporation)
• Original Assignee: Kimberly-Clark Corporation
• Inventors: Collier, L. Warren IV, Stopper, Steven R.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US08/043,887
• Time in Patent Office: 321 Days
• Field of Search: 524/505, 525/89, 525/92, 428/224, 428/903
• US Class Current: 524/505
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 53/025 modified
• CPC Class Codes: D04H 1/587 characterised by the bonding agents used
• CPC Class Codes: Y10S 428/903 Microfiber, less than 100 micron diameter
• CPC Class Codes: Y10T 442/602 Nonwoven fabric comprises an elastic strand or fiber material
• CPC Class Codes: Y10T 442/637 Including strand or fiber material which is a monofilament composed of two or more polymeric materials in physically distinct relationship [e.g., sheath-core, side-by-side, islands-in-sea, fibrils-in-matrix, etc.] or composed of physical blend of chemically different polymeric materials or a physical blend of a polymeric material and a filler material

Abstract

An elastic nonwoven web is formed from elastic fibers composed of a blend of (1) a styrene-poly(ethylene-propylene)-styrene thermoplastic elastomeric block copolymer or a mixture of a styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a styrene-poly(ethylene-butylene)-styrene elastomeric block copolymer, and (2) a tackifying resin in which the elastic nonwoven web has a stress relaxation of less than about 30 percent. The blend used to form the elastic nonwoven web and/or elastic fibers may also include a polyolefin and an extending oil.

Claims

1. Elastic fibers formed from an extrudable blend, the blend including:

(A) an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of styrene-poly(ethylene-polypropylene)-styrene and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers; and

(B) a tackifying resin,

wherein the fibers are adapted to form a nonwoven elastic web having a stress relaxation of less than about 30 percent.

2. The elastic fibers of claim 1, wherein said styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer has the formula:

##STR3## wherein m is an integer from about 38 to 337; and

n is an integer from about 500 to 1,860; and

R is a benzyl group.

3. The elastic fibers of claim 2, wherein the styrene-poly(ethylene-propylene)-styrene block copolymer has an average molecular weight ratio of polystyrene endblocks to poly(ethylene-propylene) midblocks ranging from about 10:

90 to about 25;

75.

4. The elastic fibers of claim 1 wherein the mixture of styrene-poly(ethylene-polypropylene)-styrene and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers contains at least about 40 parts by weight styrene-poly(ethylene-polypropylene)-styrene elastomeric block copolymer per 100 parts of elastomeric block copolymer.

5. The elastic fibers of claim 1, wherein the tackifying resin is selected from the group including hydrogenated hydrocarbon resins and terpene hydrocarbon resins.

6. The elastic fibers of claim 1, wherein the blend further includes a polyolefin.

7. The elastic fibers of claim 6, wherein the polyolefin is selected from the group including polyethylene, polypropylene, polybutylene, polyethylene copolymers, polypropylene copolymers, polybutylene copolymers and mixtures thereof.

8. The elastic fibers of claim 6, wherein the blend further includes an extending oil.

9. The elastic fibers of claim 8, wherein the extending oil is a mineral oil.

10. The elastic fibers of claim 1, wherein said blend comprises from about 50 to about 80 percent, by weight, of an elastomeric polymer, from about 15 to about 28 percent, by weight, of a tackifying resin, from about 3 to about 23 percent, by weight, of a polyolefin, and from about 0 to about 15 percent, by weight, of an extending oil.

11. The elastic fibers of claim 1, wherein the fibers are meltblown fibers.

12. The elastic fibers of claim 11, wherein the meltblown fibers include microfibers.

13. Elastic fibers formed from an extrudable blend, the blend consisting essentially of:

(A) an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of styrene-poly(ethylene-polypropylene)-styrene and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers;

(B) a polyolefin;

(C) a tackifying resin; and

(D) an extending oil, and

wherein said fibers are adapted to form a nonwoven elastic web having a stress relaxation of less than about 30 percent.

14. Elastic fibers formed from an extrudable blend, the blend comprising:

(A) from about 50 to about 80 percent, by weight, of an elastomeric polymer selected from the group consisting of styrene-poly(ethylene-propylene)-styrene elastomeric block copolymer and a mixture of styrene-poly(ethylene-polypropylene)-styrene and styrene-poly(ethylene-butylene)-styrene elastomeric block copolymers;

(B) from about 3 to about 23 percent, by weight, of a polyolefin;

(C) from about 15 to about 28 percent, by weight, of a tackifying resin; and

(D) from about 0 to about 15 percent, by weight, of an extending oil, and

wherein said fibers are adapted to form a nonwoven elastic web having a stress relaxation of less than about 30 percent.

15. The elastic fibers of claim 14, wherein the tackifying resin is selected from the group including hydrogenated hydrocarbon resins and terpene hydrocarbon resins.

16. The elastic fibers of claim 14, wherein the polyolefin is selected from the group including polyethylene, polypropylene, polybutylene, polyethylene copolymers, polypropylene copolymers, polybutylene copolymers and mixtures thereof.

17. The elastic fibers of claim 14, wherein the extending oil is a mineral oil.