Modulus nonwoven webs based on multi-layer blown microfibers

• US 5,176,952 A
• Filed: 09/30/1991
• Issued: 01/05/1993
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Joseph, Eugene G., Meyer, Daniel E.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US07/768,161
• Time in Patent Office: 463 Days
• Field of Search: 428/370, 428/373, 428/375, 428/378, 428/395, 428/396, 428/401, 428/903, 428/284, 428/297, 428/298, 428/286, 428/287, 428/303
• US Class Current: 442/340
• CPC Class Codes: B32B 2250/42 Alternating layers, e.g. ABAB(C), AABBAABB(C)
• CPC Class Codes: B32B 2262/0207 Elastomeric fibres
• CPC Class Codes: B32B 2262/0253 Polyolefin fibres vinyl or acrylic copolymers B32B2262/0223 or B32B2262/0246
• CPC Class Codes: B32B 2262/0276 Polyester fibres
• CPC Class Codes: B32B 2307/54 Yield strength; Tensile strength
• CPC Class Codes: B32B 27/12 next to a fibrous or filamentary layer
• CPC Class Codes: B32B 5/022 Non-woven fabric
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: D04H 1/559 the fibres being within layered webs
• CPC Class Codes: D04H 1/56 in association with fibre formation, e.g. immediately following extrusion of staple fibres
• CPC Class Codes: Y10T 442/614 Strand or fiber material specified as having microdimensions [i.e., microfiber]
• CPC Class Codes: Y10T 442/62 Including another chemically different microfiber in a separate layer
• CPC Class Codes: Y10T 442/68 Melt-blown nonwoven fabric

Abstract

A high modulus nonwoven web is produced using a high modulus material and a self-bonding material formed as multi-layer melt-blown microfibers where the web modulus is greater the MX₁ +MX₂ where M₁ and M₂ represent the modulus values of webs formed from the two materials and X₁ and X₂ represent the respective volume portions of the materials in the web fibers.

Claims

1. A melt-blown nonwoven web comprising melt-blown microfibers having at least two continuous layers throughout said fiber length comprised of at least one first layer of a self-bonding material, at melt-blowing conditions, and at least one second layer of a relatively high modulus material wherein the melt-blown web has a tensile modulus at least 1.5 times greater than a mean web modulus, M₁ X₁ +M₂ X₂, where M₁ and M₂ are the tensile modulus values of corresponding nonwoven webs of the first layer material and second layer material respectively and X₁ and X₂ are the respective volume fractions of the first and second layer materials.

2. The nonwoven web of claim 1 wherein the melt-blown web has a tensile modulus 2.5 times the mean web modulus.

3. The nonwoven web of claim 1 wherein the melt-blown web has a tensile modulus greater than corresponding webs of the first and second layer materials alone.

4. The nonwoven web of claim 1 where the relatively high modulus material has a fiber tensile modulus 100 times or more the fiber tensile modulus of the relatively more self-bonding material.

5. The nonwoven web of claim 1 wherein the relatively high modulus material comprises an orientable polymer, and the self-bonding material comprises an elastomer.

6. The nonwoven web of claim 5 wherein the orientable polymer comprises a polyolefin or a polyester.

7. The nonwoven web of claim 1 wherein the self-bonding material is a semi-crystalline polymer or a block copolymer having a soft segment wherein the semi-crystalline polymer or soft segment has a glass transition point of less than about 25°

C. and a crystallization half life, at a temperature 15°

C. below the polymer melt temperature, of greater than 50,000 seconds.

8. The nonwoven web of claim 7 wherein the crystallization half life is greater than 100,000 seconds.

9. The nonwoven web of claim 7 wherein the glass transition point or soft segment glass transition point of the polymer is less than 15°

C.

10. The nonwoven web of claim 1 wherein the self-bonding material has a glass transition temperature of less than 15°

C.

11. The nonwoven web of claim 1 wherein the self-bonding material comprises a low molecular weight polyethylene polymer or a polypropylene copolymer with a polar comonomer.

12. The nonwoven web of claim 1 wherein the microfiber average diameter is less than 10 micrometers.

13. The nonwoven web of claim 1 wherein there are at least three layers in said microfibers.

14. The nonwoven web of claim 1 wherein there are at least five layers in said microfibers.

15. The nonwoven web of claim 14 wherein the microfiber layers are alternating.

16. The nonwoven web of claim 1 wherein the unconsolidated web is 0.01 to 5 centimeters thick.