Releasable fastener systems and processes

• US 7,308,738 B2
• Filed: 01/06/2003
• Issued: 12/18/2007
• Est. Priority Date: 10/19/2002
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: General Motors Corporation (General Motors Company)
• Inventors: Barvosa-Carter, William, Browne, Alan L., Johnson, Nancy L., Momoda, Leslie A., Stanford, Thomas B.
• Primary Examiner(s): Lavinder, Jack W.
• Application Number:
  US10/337,238
• Publication Number:
  US 20040117955A1
• Time in Patent Office: 1,807 Days
• Field of Search: 244/42, 244/46, 244/48, 244/50, 244/51, 244/52, 243/04, 428/100
• US Class Current: 24/442
• CPC Class Codes: A41D 2300/326 using hooks and eyelets
• CPC Class Codes: A44B 18/0003 Fastener constructions A44B18/0023, A44B18/0046 take precedence
• CPC Class Codes: A44B 18/0007 in which each part has similar elements
• CPC Class Codes: A44B 18/0096 Shape memory materials
• CPC Class Codes: A44D 2203/00 Fastening by use of magnets
• CPC Class Codes: B64C 33/02 Wings; Actuating mechanisms therefor
• CPC Class Codes: C08L 2201/12 Shape memory
• CPC Class Codes: F16B 2200/77 Use of a shape-memory material
• CPC Class Codes: F16B 2200/81 Use of a material of the hooks-and-loops type
• CPC Class Codes: F16B 2200/83 Use of a magnetic material
• CPC Class Codes: F16B 5/07 by means of multiple interengaging protrusions on the surfaces, e.g. hooks, coils,
• CPC Class Codes: F16F 2224/045 magnetorheological
• CPC Class Codes: Y10T 24/27 including readily dissociable fastener having numerous, protruding, unitary filaments randomly interlocking with, and simultaneously moving towards, mating structure [e.g., hook-loop type fastener]
• CPC Class Codes: Y10T 24/2742 having filaments of varied shape or size on same mounting surface
• CPC Class Codes: Y10T 428/24017 Hook or barb

Abstract

A releasable fastener system comprises a loop portion and a hook portion. The loop portion includes a support and a loop material disposed on one side thereof. The hook portion generally includes a support and a plurality of closely spaced upstanding hook elements extending from one side thereof, wherein the plurality of hook elements comprises or incorporates a shape memory polymer. When the hook portion and loop portion are pressed together they interlock to form a releasable engagement. The resulting joint created by the engagement is relatively resistant to shear and pull forces and weak in peel strength forces. Introducing a thermal activation signal to the plurality of hook elements causes a change in shape orientation and/or flexural modulus that effectively reduces the shear and/or pull off forces in the releasable engagement. In this manner, disengagement of the releasable fastener system provides separation of the hook portion from the loop portion under controlled conditions. Also disclosed herein are processes for operating the releasable fastener system.

Claims

1. A releasable fastener system comprising:

a cavity portion comprising a support and a plurality of cavities disposed within the support;

a hook portion comprising a support and a plurality of hook elements disposed on a surface thereon, wherein the plurality of hook elements comprises a shape memory polymer and, in an unpowered state, comprises shapes complementary to the plurality of cavities; and

a thermal activation device coupled to the plurality of hook elements, the thermal activation device being operable to selectively provide a thermal activation signal to the plurality of hook elements and change a shape orientation and/or flexural modulus thereof to reduce a shear force and/or a pull-off force of an engaged hook and cavity portion.

2. The releasable fastener system of claim 1, wherein the shape memory polymer comprises polyphosphazenes, poly(vinyl alcohols), polyamides, polyester amides, poly(amino acid)s, polyanhydrides, polycarbonates, polyacrylates, polyalkylenes, polyacrylamides, polyalkylene glycols, polyalkylene oxides, polyalkylene terephthalates, polyortho esters, polyvinyl ethers, polyvinyl esters, polyvinyl halides, polyesters, polylactides, polyglycolides, polysiloxanes, polyurethanes, polyethers, polyether amides, polyether esters, poly(methyl methacrylate), poly(ethyl methacrylate), poly(butyl methacrylate), poly(isobutyl methacrylate), poly(hexyl methacrylate), poly(isodecyl methacrylate), poly(lauryl methacrylate), poly(phenyl methacrylate), poly(methyl acrylate), poly(isopropyl acrylate), poly(isobutyl acrylate) and poly(octadecyl acrylate), polystyrene, polypropylene, polyvinyl phenol, polyvinylpyrrolidone, chlorinated polybutylene, poly(octadecyl vinyl ether), ethylene vinyl acetate, polyethylene, poly(ethylene oxide)-poly(ethylene terephthalate), polyethylene/nylon (graft copolymer), polycaprolactones-polyamide (block copolymer), poly(caprolactone) dimethacrylate-n-butyl acrylate, poly(norbornyl-polyhedral oligomeric silsequioxane), polyvinylchloride, urethane/butadiene copolymers, polyurethane block copolymers, styrene-butadiene-styrene block copolymers, or copolymers thereof.

3. The releasable fastener system of claim 1, wherein the thermal activation signal comprises heating the shape memory polymer above a first transition temperature to effectuate a change in the shape orientation and/or flexural modulus of the plurality of hook elements.

4. The releasable fastener system of claim 1, wherein the shape memory polymer further comprises a conductive element.

5. The releasable fastener system of claim 1, wherein the shape memory polymer further comprises conductive filler.