Abstract: A method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided non-metallic inorganic particles which are gel forming and insoluble in water and polar organic liquids into the foam cells. A stable liquid suspension or gel, preferably aqueous is prepared using these particles. An opacifier such as finely divided titanium dioxide or tin oxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles and further improves the flame resistance.

Abstract: A method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided non-metallic inorganic particles which are gel forming and insoluble in water and polar organic liquids into the foam cells. A stable liquid suspension or gel, preferably aqueous is prepared using these particles. An opacifier such as finely divided titanium dioxide or tin oxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles and further improves the flame resistance.

Abstract: A method of improving the flame resistance of foams, such as open cell polyimide foams, through the introduction of finely divided non-metallic inorganic particles which are gel forming and insoluble in water and polar organic liquids into the foam cells. A stable liquid suspension or gel, preferably aqueous is prepared using these particles. An opacifier such as finely divided titanium dioxide or tin oxide may also be added. An open cell foam product is placed in the gel until the cells fill with the gel. Excess gel is removed and the foam is dried, leaving the particles trapped in the cells. If desired, the foam may be post treated, such as by compression at the stabilizing temperature, resulting in a densified foam which further mechanically traps the particles and further improves the flame resistance.

Abstract: A method of making high efficiency, flame resistant polyimide foam insulation particularly suitable for insulating plastic pipes and forming ducts. Typically a sheet of polyimide foam which has been foamed unconstrained is placed between opposed caul plates, squeezed to a thickness less than the original thickness and heated to stabilize the new sheet thickness. Face sheets coated with a polyimide adhesive can then be placed against the stabilized foam faces and heated between plates to bond the face sheets to the foam. Also, a sheet of foam which had been impregnated with polyimide resin precursor can be placed against the stabilized sheet and the resin precursor simultaneously cured and the sheet bonded to the stabilized foam. A variety of flat, tubular or other shapes can be made by this method. The resulting insulation panels, tubes or the like have greatly improved flame resistance and excellent thermal insulation characteristics.