Fire retardant insulation

Abstract

A flame retardant thermal insulation material comprising a dry, shredded cellulosic material, such as newsprint, which is coated with a dry phosphorous-containing, flame retardant composition. The composition is one which is capable of decomposing near the ignition temperature of the shredded paper, which is between 120 degrees and Celsius and 250 degrees Celsius and preferably includes a plurality of compounds which decompose at different temperatures spaced within this range to provide the stagewise release of combustion inhibiting agents. The composition can be a single compound such as calcium phosphate but preferably is a combination of similar compounds such as (NH.sub.4).sub.2 HPO.sub.4, CaH.sub.4 (PO.sub.4).sub.2, CaHPO.sub.4 and triple super phosphate. Further, the phosphorous composition is preferably combined with urea. Elemental sulfur powder may be included with any of the previous compositions as a smoke retardant. The paper and flame retardant composition are maintained in the dry solid state during processing, application and use. The insulation is manufactured by shredding the paper and thoroughly mixing it with the finely ground, powdered flame retardant composition to intimately coat the paper with the flame retardant powder. The shredded, coated paper may be bagged for later use as poured or blown in insulation or it may be filled into elongated plastic envelopes to form insulative batting. Air may be evacuated from the bags or envelopes.