Retroreflective sheet with nonwoven elastic backing

• US 5,316,838 A
• Filed: 03/26/1993
• Issued: 05/31/1994
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Joseph, Eugene G., Crandall, Michael D.
• Primary Examiner(s): Bell, James J.
• Application Number:
  US08/037,902
• Time in Patent Office: 431 Days
• Field of Search: 428/283, 428/284, 428/286, 428/297, 428/298, 428/402, 428/403, 428/406, 428/432, 428/354, 428/903, 428/910, 428/285, 428/912.2, 428/323, 428/325, 359/515, 359/534, 359/535, 359/536
• US Class Current: 442/183
• CPC Class Codes: A61F 13/0269 Tapes for dressing attachment for stoma bags A61F5/443; for nappies or sanitary towels A61F13/58; wound closure tapes A61B17/085; for surgical drapes A61B46/00; attaching catheters A61M25/02
• CPC Class Codes: A61F 13/537 characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer A61F13/538 takes precedence
• CPC Class Codes: A61F 2013/00604 Multilayer
• CPC Class Codes: A61F 2013/530138 characterized by the fibre length
• CPC Class Codes: A61F 2013/530218 followed by heat treatment
• CPC Class Codes: A61F 2013/530226 with polymeric fibres
• CPC Class Codes: A61F 2013/530343 being natural fibres
• CPC Class Codes: A61F 2013/53445 from several sheets
• CPC Class Codes: A61F 2013/53908 with adhesive
• CPC Class Codes: A61F 2013/5395 with thermoplastic agent, i.e. softened by heat
• CPC Class Codes: A61F 2013/53983 with hook and loop-type fastener or the like
• CPC Class Codes: D04H 1/54 by welding together the fibres, e.g. by partially melting or dissolving in combination with needling D04H1/485
• 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 428/91 Product with molecular orientation
• 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 428/2848 Three or more layers
• CPC Class Codes: Y10T 428/2922 Nonlinear [e.g., crimped, coiled, etc.]
• CPC Class Codes: Y10T 428/2929 Bicomponent, conjugate, composite or collateral fibers or filaments [i.e., coextruded sheath-core or side-by-side type]
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2991 : Coated
• CPC Class Codes: Y10T 428/2996 : Glass particles or spheres
• CPC Class Codes: Y10T 442/2754 : Pressure-sensitive adhesive
• CPC Class Codes: Y10T 442/3016 : Including a preformed layer other than the elastic woven fabric [e.g., fabric or film or foil or sheet layer, etc.]
• CPC Class Codes: Y10T 442/3065 : Including strand which is of specific structural definition
• CPC Class Codes: Y10T 442/3382 : Including a free metal or alloy constituent
• CPC Class Codes: Y10T 442/3911 : Natural or synthetic rubber sheet or film
• CPC Class Codes: Y10T 442/3919 : Including particulate material other than fiber
• CPC Class Codes: Y10T 442/602 : Nonwoven fabric comprises an elastic strand or fiber material
• CPC Class Codes: Y10T 442/615 : Strand or fiber material is blended with another chemically different microfiber in the same layer
• CPC Class Codes: Y10T 442/62 : Including another chemically different microfiber in a separate layer
• CPC Class Codes: Y10T 442/641 : Sheath-core multicomponent strand or fiber material
• CPC Class Codes: Y10T 442/68 : Melt-blown nonwoven fabric

Abstract

A retroreflective sheet comprising a monolayer of retroreflective elements partially embedded in and partially protruding from the front surface of a binder layer and a backing bonded to the back surface of the binder layer wherein the backing is elastic and comprises a highly conformable and deformable nonwoven web comprising melt-blown microfibers having multiple layers of a relatively low modulus material and a high modulus material.

Claims

1. A retroreflective sheet comprising a monolayer of retroreflective elements partially embedded in and partially protruding from the front surface of a binder layer and a backing bonded to the back surface of said binder layer wherein said backing is elastic and comprises extensible nonwoven web comprising melt-blown microfibers each of said microfibers having at least two substantially continuous layers throughout said microfiber length comprised of at least one first layer of a low modulus material and at least one second layer of a relatively nonelastic higher modulus material capable of undergoing substantial permanent deformation.

2. The sheet of claim 1 wherein certain of said multi-layer microfibers are crimped, at least one second layer of relatively nonelastic material of said crimped multi-layer fibers being oriented.

3. The sheet of claim 1 wherein said low modulus material of said microfibers comprises an elastomer and said sheet displays asymmetrical elasticity created by stretching said web in at least one direction.

4. The sheet of claim 1 wherein said low modulus material of said microfibers comprises an elastomer and said sheet displays asymmetrical elasticity in more than one direction created by stretching said web by differing degrees in said more than one direction.

5. The sheet of claim 3 wherein said sheet can be elastically stretched by more than 50% and recovered in its direction of elasticity.

6. The sheet of claim 3 wherein said sheet can be elastically stretched by less than 50% and recovered in its direction of elasticity.

7. The sheet of claim 4 wherein said sheet can be elastically stretched by more than 50% and recovered in its direction of elasticity.

8. The sheet of claim 1 further comprising a layer of adhesive on the back side of said backing.

9. The sheet of claim 1 wherein said sheet has an extensibility of at least 100%.

10. The sheet of claim 1 wherein said low modulus material comprises an elastomer and said sheet shrinks when heated substantially above ambient conditions.

11. The sheet of claim 10 wherein said web shrinks by at least 10% when heated above about 60°

C.

12. The sheet of claim 1 further comprising at least one adhesive layer intermediate said binder layer and said backing.

13. The sheet of claim 12 wherein said sheet has an extensibility of at least 50%.

14. The sheet of claim 12 wherein said sheet has an extensibility of at least 150%.

15. The sheet of claim 1 wherein the layers within said microfibers are concentric with an outer sheath layer and at least one internal core layer.

16. The sheet of claim 1 wherein the layers within said microfibers are longitudinally layered.

17. The sheet of claim 15 wherein the outer sheath layer comprises a heat or sonic bondable layer with at least one internal core layer of an elastomeric material.

18. The sheet of claim 17 wherein said outer bondable layer comprises an ethylene copolymer.

19. The sheet of claim 17 wherein said outer bondable layer comprises an ethylene polymer.

20. The sheet of claim 18 wherein said inner elastomeric layer comprises a polyurethane.

21. The sheet of claim 1 wherein the average fiber diameter is less than about 10 micrometers.

22. The sheet of claim 16 wherein said melt-blown microfibers have 3 or more layers.

23. The sheet of claim 16 wherein said melt-blown microfibers have 5 or more layers.

24. The sheet of claim 16 wherein at least one outer layer comprises a heat or sonic bondable layer with at least one layer of an elastomeric material.

25. The sheet of claim 24 wherein said outer bondable layer comprises an ethylene polymer or copolymer.

26. The sheet of claim 1 wherein said binder layer has a thickness between about 50 and 250 microns.

27. The sheet of claim 1 wherein said binder layer has a thickness between about 75 and 100 microns.

28. The sheet of claim 1 wherein said binder layer comprises at least one of the following:

isocyanatecurable polyester, polytetramethylene oxide glycol, polyester polyol, hydroxy-terminated polybutadiene, polycaprolactone polyol, polybutylene oxide glycol, and polypropylene oxide glycol, aliphatic polyisocyanate, aromatic polyisocyanate, latex, or rubber.

29. The sheet of claim 1 wherein said retroreflective elements comprise substantially transparent microspheres, the front surfaces of which protrude from said binder layer, said microspheres having reflective means on the rear surfaces thereof.

30. The sheet of claim 29 wherein said reflective means comprise at least one of the following:

metal coatings, metal flakes, or dielectric coating.

31. An article of clothing comprising a sheet of claim 1.

32. A sweat band comprising a sheet of claim 1.