Process for imparting durable flame retardancy to fabric, fibers and other materials and improved product produced thereby

Claim 1

A process for grafting a fire-retarding additive selected from the group consisting or phosphorus-rich and halogen-rich fire-retarding compounds to a flammable fibrous fabric selected from the group consisting of nylon, polyester, and cellulosic materials, that comprises, applying to the fabric a solution of the additive and an effective amount of a copolymerization-grafting compound for effecting copolymerization with the additive, with the solids content of the solution selected to correspond to a predetermined desired add-on level within the range of substantially 15-40% by weight, at least partly drying the fabric by evaporating moisture therefrom to improve the graft efficiency, irradiating the fabric, so treated, with an electron curtain beam substantially perpendicular to the fabric for uniformity of irradiation, with the energy of the beam adjusted to an energy level within the range of substantially 50-250 keV and considerably below the energy required for the electrons of the beam to penetrate the average thickness of the material constituting the fabric, scattering the electrons of the beam between the fabric fibers to extend the effective range of electron penetration, moving the fabric past the beam at a speed within the range of about 7-50 meters per minute, and adjusting the dose of the electron beam radiation delivered to the fabric to a level within the range of substantially 2-5 megarads.