DETAILED DESCRIPTION I claim: 1.
A composite formed of (a) a core in the form of a foamed polyimide and (b) a backing layer bonded to one face of the core, said backing layer comprising a thin metal foil bonded to the core with a visco-elastic adhesive.
2.
A composite as defined in claim 1 wherein the foam has a density within the range of 0.
5 to 5 lbs/ft.
sup.
3.
3.
A composite as defined in claim 1 wherein the composite also includes a facing layer bonded to the core.
4.
A composite as defined in claim 3 wherein the facing layer is a metal foil.
5.
A composite as defined in claim 1 wherein the polyimide is prepared by foaming a polyimide formed by reaction of an aromatic tetracarboxylic dianhydride or a derivative thereof with one or more diamines.
6.
A composite as defined in claim 5 wherein the anhydride is a benzophenone tetracarboxylic diester.
7.
A composite as defined in claim 1 wherein the adhesive is an acrylic adhesive.
8.
A composite as defined in claim 1 wherein the metal foil is an aluminum foil.
9.
A composite as defined in claim 1 wherein polyimide foam is prepared from the diamines diaminopyridine and methylene dianiline.
10.
A composite as defined in claim 1 which includes a backing layer on each face of the core bonded to the core with a visco-elastic adhesive.
11.
A composite as defined in claim 9 wherein one metal foil includes a strippable protective layer bonded thereto.
Description:
This invention relates to polyimide composites and, more specifically, to polyimide composites for use in vibration damping and thermal insulation applications.
As is now well known to those skilled in the art, polyimides have found wide-spread use in the aircraft and aerospace industries by reason of their lightweight, chemical inertness, curing properties, fire resistance, and resilience over broad temperature ranges.
Such polyimides are described in detail in U.
S.
Pat.
Nos.
4,305,796; 4,363,690; 4,367,296; 4,296,208; 4,332,656; 4,355,120; 3,966,652; 4,070,312; 4,153,783; 4,241,114; 4,241,193; 4,255,488; 4,299,787; and 4,319,000
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Vibration and Earthquake Isolation 
