Film materials based on multi-layer blown microfibers

• US 5,190,812 A
• Filed: 09/30/1991
• Issued: 03/02/1993
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: 3M Company
• Original Assignee: 3M Company
• Inventors: Rustad, James A., Joseph, Eugene G.
• Primary Examiner(s): Lesmes, George F.
• Assistant Examiner(s): SHELBORNE, KATHRYNE E
• Application Number:
  US07/768,174
• Time in Patent Office: 519 Days
• Field of Search: 428/40, 428/41, 428/131, 428/132, 428/137, 428/192, 428/296, 428/343, 428/352, 428/354, 428/500, 428/520, 428/903, 428/297, 428/298, 128/156, 156/167
• US Class Current: 442/350
• CPC Class Codes: D01D 5/0985 by means of a flowing gas (e.g. melt-blowing)
• 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: Y10S 428/903 Microfiber, less than 100 micron diameter
• CPC Class Codes: Y10S 428/915 Fraud or tamper detecting
• CPC Class Codes: Y10S 428/916 Fraud or tamper detecting
• CPC Class Codes: Y10T 428/28 Web or sheet containing structurally defined element or component and having an adhesive outermost layer
• CPC Class Codes: Y10T 442/2754 Pressure-sensitive adhesive
• CPC Class Codes: Y10T 442/625 Autogenously bonded
• CPC Class Codes: Y10T 442/626 Microfiber is synthetic polymer
• CPC Class Codes: Y10T 442/68 Melt-blown nonwoven fabric

Abstract

An extensible transparent film is provided having a continuous phase of a low modulus or elastomeric material and an included array of entangled microfibers. The film turns opaque and increases moisture vapor transmission when stretched.

Claims

1. A transparent film formed from a nonwoven web of microfibers having a substantially continuous phase of a thermoplastic low modulus material having a Young'"'"'s modulus of less than about 10⁷ N/m² and within said continuous phase of thermoplastic low modulus material a discontinuous array of entangled microfibers of an extensible thermoplastic material.

2. The transparent film of claim 1 wherein the continuous phase comprises at least 2.0 volume percent of the film and the film will exhibit at least a 30% change in opacity when elongated from 5 to 50%.

3. The transparent film of claim 1 wherein the microfibers have an average thickness of less than 10 microns.

4. The transparent film of claim 1 wherein the microfibers have an average thickness of less than 1 micron.

5. The transparent film of claim 1 wherein the microfibers have an average thickness of less than 0.1 microns.

6. The transparent film of claim 1 further comprising a pressure-sensitive adhesive layer.

7. The transparent film of claim 1 wherein the low modulus material comprises a polyurethane and the thermoplastic microfibers comprise a polyolefin.

8. The transparent film of claim 1 wherein the low modulus material has a Young'"'"'s modulus of less than 10⁶ N/m².

9. The transparent film of claim 1 wherein the low modulus material is an elastomer.

10. The transparent film of claim 1 wherein the microfibers are formed from a non-elastomeric material having a Young'"'"'s modulus of greater than 10⁶ N/m².

11. The transparent film of claim 1 wherein the microfibers are formed from a non-elastomeric material having a Young'"'"'s modulus of greater than 10⁷ N/m².

12. The transparent film of claim 1 wherein the microfibers have an average diameter of less than 10 micrometers.

13. The transparent film of claim 1 wherein the moisture vapor transmission of the film increases when the film is stretched by 20% or more.

14. The transparent film of claim 1 wherein the moisture vapor transmission of the film increases when the film is stretched by at least 1000% or more.

15. The transparent film of claim 1 wherein the moisture vapor transmission of the film increases when the film is stretched by at least 2000% or more.

16. The transparent film of claim 6 wherein the film has a Young'"'"'s modulus of less than 50,000 PSI.

17. The transparent film of claim 6 wherein the film has a Young'"'"'s modulus of from 5,000 to 30,000 PSI.