Various combustible materials such as paper, wood, leather, cloth and textiles of animal or vegetable origin and, especially, cellulosic materials suitable for insulation may be rendered fire retardant by treating the same with an aqueous solution comprising about 10 to 60 per cent of a blend of ammonium nitrate liquor and urea liquor, this blend can be within a range of 44.5% ammonium nitrate, 35.4% urea, and 20.3% water to 39.5% ammonium nitrate, 30.5% urea, and 30% water; about 10 to 50 per cent of an ammoniated poly phosphate having approximately 10 per cent nitrogen and approximately 34 per cent phosphoric acid; about 0 to 25 per cent molasses, starch or sugar or mixtures thereof; and up to about 3 per cent of a strong base such as sodium hydroxide.

Cellulosic materials such as wood chips, textile fibers and the like are treated to produce products such as particle board having enhanced fire and heat resistant properties. For example, wood chips are saturated with an eqimolar aqueous solution of monoammonium phosphate and diammonium phosphate. A metal hydroxide is added to the solution. The saturated wood chips are dried and mixed with a modified glue composition. The glue that which contains urea formaldehyde and/or phenolic resin is in powdered form and dissolved in water. The treated wood chips and modified glue is then mixed, formed into a mat and placed under pressure at about 120.degree. C. for 8 to 15 minutes. The pressure may range from about 300 to 400 psi.

In the manufacture of synthetic foams and also especially in that of timber materials using urea-formaldehyde condensate binders, the mol ratio between urea and formaldehyde is decisive for the resultant final rigidity and the presence of free gaseous formaldehyde. In order, with a favourable mol ratio, to reduce the quantity of gaseous formaldehyde remaining in the timber material and at the same time to obtain effective fire resistance in both synthetic foams and timber materials adhesively secured with isocyanate, the invention proposes a combination of effective substances to be added to the initial raw materials as a granulate with a grain size of 80 to 1,500 my.

The invention relates to fire protectants containing aluminium hydroxide, which additionally contain natural and/or nearly natural calcium borate, their production and use, and semifinished goods and finished parts containing these fire protectants.

Fire retardant properties are provided for cellulose insulation materials by the addition of a fire retardant composition comprising from 60 to 85% of bauxite, from 5 to 30% dolomite, and from 5 to 30% boric acid. Loading factors of from about 20 to about 35% fire retardant are effective to meet applicable federal specifications for flame spread and smoldering.