Abstract
Durable fire retardants based on phosphoric acid-containing dicyandiamide-formaldehyde condensation products (H3PO4 DFAC)were applied to filter paper and sliced veneers. Thefire retardants give clear, acidic aqueous solutions. Upon aging, these aqueous solutions transform first tohydrophilic colloid, then to water dispersible gel and finally upon drying to a water-insoluble resin.
Fire retardant treatment is done by soaking samples in an aqueous solution of H3PO4 DFAC, drying at 105°C for 24 hours, and curing at 160°C for 30 minutes.
In filter paper and sliced veneer test specimens treated with a solution of higher phosphoric acidmolar ratio, fire retardance is attained at lower resin add-on level than with a mixture of phosphoricacid and dicyandiamide. Satisfactory fireproofing properties can be obtained in filter paper andsliced veneers at resin add-on levels as low as 5-10%, with a few exceptions.
