Fire-retarding laminated element and a method of controlling expansion of expandable, fire-retarding foaming-agent layers

Claim 1

A fire-retarding laminated element comprising at least one foaming-agent layer capable of expanding at high temperatures and at least one restricting layer disposed adjacent to said foaming-agent layer for restricting the expansion of said foaming-agent layer so that, after expanding, said foaming-agent layer has smaller pores than it would have after unrestrained expansion in the absence of said restricting layer; said restricting layer comprising fillers of fibrous, flake-like and/or platelet-like fibers of at least a carbon selected from the group consisting of pitchbased carbon, high tenacity (HT) carbon, high strain (HST) carbon, intermediate modulus (IM) carbon, pre-ox carbon and carbon black, and imparting a relatively stable structure to the combination formed of said layers after high temperature expansion of said layers, said layers having been prepared from epoxy resin based materials, and said restricting layer has a thickness of one to three times the thickness of said foaming-agent layer prior to heat induced expansion.