GB657599A - Method of improving the fire-and heat-resistance of materials and compositions for use therein - Google Patents

Abstract

A composition for imparting fire-resistance to combustible materials comprises a thermosetting resin salt of a basic nitrogen-containing anion exchange resin with at least 2 milli-equivalents per gram of said resin of a strong non-oxidizing inorganic acid. The inorganic acid, preferably having a dissociation constant of 10-3 or higher, may be hydrochloric acid or other hydrogen halide or a polyvalent acid such as sulphuric or phosphoric. The anion exchange (or acid-absorbent) resins are such basic resins as are capable of forming resin salts from which the acid is no longer completely removable by alkali or acid treatment and include those obtained when basic nitrogen-containing organic compounds such as amines or guanidine are condensed with aldehydes, hydroxy-aldehydes (e.g. sugars or starches) or with mixtures of aldehydes and ketones so that not all the basic groups are linked to aldehyde, e.g. by condensing (1) m-substituted aromatic amines or aromatic polyamines with aldehydes and/or carbohydrates, with or without ketones; (2) aliphatic polyalkylene polyamines with aldehydes or carbohydrates and ketones or phenols; (3) a strongly basic derivative of cyanamide such as guanidine or guanylurea with a weakly-basic derivative of cyanamide such as urea, thiourea, dicyandiamide, or melamine with an aldehyde and, optionally, a carbohydrate. The resins are combined with as much acid as possible which, in general, is about 15 milli-equivalents of acid per gram up to 25 milli-equivalents by forming the resin in the presence of the acid or treating it with aqueous acid. Combustible materials such as wallboard, fibreboard, cardboard, wood, plywood, fabrics and paper may be coated or impregnated with the resin salt. The latter may be in a low state of polymerization and be employed, for example, in an aqueous dispersion containing wheat paste, as an adhesive for laminar material or veneers, or for coating metal surfaces or may be dispersed in a heat-cured insoluble state, in a liquid medium containing a film-forming agent such as a drying oil, an alkyd, oil-modified alkyd, or other film-forming resin or a cellulose derivative and be employed as a coating composition. Pigments, plasticizers such as p-toluene sulphonamide and fillers may be added. In examples: (1) (a) guanidine carbonate and melamine were reacted with aqueous formaldehyde and concentrated phosphoric acid added until CO2 evolution stopped. The gel formed on heating the viscous dispersion was washed free of excess phosphoric acid; (b) the viscous dispersion may be used as a coating composition; (d) the gel may be ground with alkyd resin, titanium dioxide, thinner and cobalt and lead driers to give a coating composition; (e) guanidine carbonate and melamine were reacted with aqueous formaldehyde, concentrated phosphoric acid added and the mixture heated to form a gel which was washed and dispersed in an alcoholic solution of ethyl cellulose; (f) fabric was dipped into a liquid composition-similar to that of (e) and containing a plasticizer, e.g. p-toluene sulphonamide or urea; (g), (h) a dispersion similar to that of (b) was used as an adhesive both with, and without, wheat paste; (2) a urea, guanidine carbonate and formaldehyde product was treated with concentrated sulphuric acid; (3) a melamine, guanidine carbonate and formaldehyde product was treated with sulphuric acid; (4) m-phenylenediamine dihydrochloride was reacted with formaldehyde in the presence of concentrated hydrochloric acid to give a resin hydrochloride; (5) as in (4) with the addition of dicyandiamide; (6) a phenol, triethylene tetramine and formaldehyde resin was treated with phosphoric acid; (7) triethylene tetramine, phosphoric acid, aqueous formaldehyde and acetone were refluxed; (8) deAcidite ionexchanger resin was treated with phosphoric acid, and washed, the washed product being mixed into a varnish. U.S.A. Specifications 2,198,874, 2,246,527, 2,251,234, 2,259,169, 2,290,345, 2,341,907, 2,354,671, 2,356,151 and 2,362,086 are referred to. The Specification as open to inspection under Sect. 91 comprises also the use of the solid resin salt in moulding or as a dust to protect combustible material against fire. This subject-matter does not appear in the Specification as accepted.