The September 2014 issue of "Kitplanes" magazine has a nice article about building foam seats, with suggestions for layering different kinds and densities of foam (including CONFOR) to achieve optimal crash protection and comfort.

One statement by the author is particularly relevant to the original question:

"I recommend either Keyston #4011P General Purpose Spray Adhesive or 3M FoamFast 74 Spray Adhesive. Regular spray adhesives not designed for foam, such as 3M 77 are not recommended- they appear to bond at first, but after a few days, the foam will delaminate."