Compositions – Fire retarding
Patent
1990-10-23
1991-12-31
Stoll, Robert L.
Compositions
Fire retarding
252607, 252608, 106 1812, 106 1832, B09K 2100
Patent
active
050769693
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to fire-retardants.
SUMMARY OF THE INVENTION
A first composition of the present invention comprises a mixture or reaction product of a fire-retardant ammonium salt, urea or biuret, and boric acid.
A second product of the invention comprises a non-adherent substrate sheet bearing a plastic composition of a sodium silicate-impregnated mat.
DESCRIPTION OF THE INVENTION
The salt in the first composition is preferably selected from monoammonium phosphate, diammonium phosphate, ammonium sulphamate, ammonium sulphate, and mixtures thereof. The first composition can exist in dry form, e.g. as a white, water-soluble powder, or it may be provided in aqueous solution, for which purpose a surfactant may be added. The actual components of the first composition of the invention may be urea salts, e.g. urea (poly)phosphates and urea borates.
A first composition of the invention is usually prepared by first mixing the ammonium salt, urea or biuret and boric acid to give a dry mixture which may then be dissolved in water. With respect to the amount of solids, there may be 25-75% by weight of the salt (or mixture of ammonium salts), 10-40% by weight of urea or biuret and 10-30% by weight boric acid. Because these components may react to give the desired reaction product, alternative components may be used to give the same or a similar result. A first composition of the invention in aqueous form may comprise 5-40% by weight of the solids.
A first composition of the invention, usually in aqueous form, can be applied to a variety of substrates to impart fire-retardancy. Application may be by casting, spraying or any other suitable technique. The substrate may be, for example, metal, wood, wood-derived products, and textiles, e.g. of natural fibres or of a blend of natural and synthetic materials.
For any particular application, a first composition of the invention may include various additives which facilitate its use. For example, a storage-stable liquid fire-retardant suitable for protecting, e.g., wood, may be prepared by adding water glass (which of course has fire-retardant properties) to an aqueous first composition of the invention. A corrosion inhibitor such as urotropine (say in an amount of up to 0.5% by weight of the composition) may be added where the first composition is to be applied to a metal, e.g. steel, structure. Portland cement may be added, for extra strength, e.g. in an amount of up to 7% by weight of the first composition. Depending on the application, an anionic or cationic surfactant may be suitable.
A first composition of the invention may comprise a filler such as glass microspheres, perlite, ballotini, vermiculite, mineral wool or waste from ground leather, mineral sanding or foundry sand. Fillers having a particle size of 200-300 mesh are suitable. A foaming agent, e.g. an anionic or neutral surfactant, may be added if an expanded/aerated structure is desired. Another preferred additive is a hardener such as sodium silicofluoride or polyethylene/polypropylene glycol diacetate. Especially for spraying, a resin such as a low-viscosity melamine-formaldehyde, urea-formaldehyde or acrylic latex may be included, without reducing fire-retardancy. Dyes or pigments may be added, as desired.
For application by spraying, to give a filled coating, a double-feed gun or other means, whereby the fire-retardant formulation is prepared immediately before application, may be used. For example, one feed comprises a liquid first composition of the invention and hardener (freshly-prepared) and the other comprises filler.
Use of first compositions of the invention provides coatings which have good heat-resistance. On rigid foam materials such as polystyrene or polyurethane, the coated product can resist heat and fire, and the coating may remain intact while the foam melts. If desired, a water-impermeable coating may be applied in addition.
Suitable amounts of additives will be apparent from the following illustrative Examples, in which all parts and percentages are by
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patent: 4448841 (1984-05-01), Glass et al.
patent: 4560485 (1985-12-01), Szekely et al.
patent: 4725382 (1988-02-01), Lewchalermwong
patent: 4784918 (1988-11-01), Klett et al.
patent: 4806620 (1989-02-01), Klett et al.
patent: 4956217 (1990-09-01), Heitkamp
Bhat Nina
Pyrotex Ltd.
Stoll Robert L.
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